Occasional review Effects of cigarette smoke epithelial ... · Thorax 1994;49:825-834 825 Occasional review Effects ofcigarette smokeonepithelial cells ofthe respiratory tract Janice

825Thorax 1994;49:825-834

Occasional review

Effects of cigarette smoke on epithelial cells of therespiratory tract

Janice A Dye, Kenneth B Adler

Chronic inhalation of cigarette smoke is associ-ated with mucus hypersecretion, mucus pool-ing, pulmonary connective tissue damage, andchronic airflow obstruction.

Cigarette smoke has therefore been causallylinked to the development of chronic obstruc-tive pulmonary disease (either chronic bron-chitis or emphysema),' increased airway res-ponsiveness,2 exacerbations of asthma,3impaired pulmonary immune function,4 andincreased pulmonary infections.5 Cigarettesmoke has also been established as an importantrisk factor for lung,6 laryngeal,7 and nasal neo-plasia.5 Pathogenetic mechanisms related tosmoke-induced respiratory perturbations, how-ever, are not fully understood.One cell type in the lung that may play a

major part in the pathogenesis of cigarettesmoke-induced lesions is the airway epithelialcell. These cells line the lumen of the airways,and thus are in a unique position to interactdirectly with inhaled cigarette smoke. Mostresearch involving cigarette smoke and airwayepithelial cells has focused on the "target" cellresponses of these cells in relation to theirrelatively simple roles in barrier and mucocili-ary clearance functions. Depending in part onthe chronicity of exposure, certain functionsmay be altered - for example, ciliary beating,mucus secretion. It has recently become appar-ent, however, that airway epithelial cells mayalso act as "effector" cells, playing pivotal rolesin regulation of airway reflexes, immunologicaland inflammatory responses, and maintenanceof bronchodilation. As part of their overallresponse to chronic insult these cells are capableof producing and/or releasing a number ofinflammatory mediators, or undergoing altera-tions in expression of cell adhesion molecules -processes that may initiate or perpetuate airwayinflammation.9 To date the influence of cigar-ette smoke on effector functions of epithelialcells has yet to be investigated in detail.Much of the information presented herein is

based on acute in vitro cigarette smoke expos-ures of epithelial cell cultures or airwayexplants, and on relatively acute human orlaboratory animal exposures. Thus, non-neo-plastic and non-emphysematous end points ofrespiratory disease have been emphasised.Nevertheless, early events in the response tocigarette smoke or its components may be criti-cal, and certainly an understanding of theseevents may help to elucidate the pathogeneticmechanisms of many chronic respiratory dis-eases.

Components of cigarette smokeChemical analytical studies have identified over3800 compounds in tobacco smoke.'" Main-stream cigarette smoke is composed of a com-plex mixture of gases and condensed tar par-ticles. In experimental studies cigarette smokeis often separated into two phases by a glassfibre filter that retains nearly all particulatematter greater than 01 ptm in diameter. Theretained particulate matter is commonlyreferred to as the "tar" phase, while the mater-ial passing through the filter is referred to as the"gas" phase. Known toxins and carcinogenshave been identified in both the gaseous andparticulate phases." Sidestream smoke (smokeemitted from the burning tip of the cigarette) isthe major constituent of environmental tobaccosmoke. The chemical composition and gas-to-particle associations of environmental tobaccosmoke may be different from that of main-stream smoke, owing to prolonged time andcooling in the air.'2 Sidestream cigarette smokeemissions contain carbon monoxide, ammonia,formaldehyde, benzene, nicotine, acrolein, var-ious gases and particles, and an assortment ofpotentially genotoxic and/or carcinogenic or-ganic compounds.'3 Increased pulmonary parti-culate burden due to cigarette smoke may alsoplay a part in respiratory disease.'4 Recent epi-demiological findings have indicated adverseeffects of particulate air pollutants at concentra-tions below currently permissible levels.'5 Res-pirable suspended particles in indoor air inhomes may increase from approximately 30 jtg/m3 to greater than 60 jg/M3 due to accumulationof environmental tobacco smoke.'6The reported effects of "cigarette smoke"

may include that of mainstream smoke, variablyaged environmental tobacco smoke/sidestreamand exhaled smoke, gaseous phase componentsonly, particulate phase components only, orindividual chemical compounds such as acro-lein,'7 acetaldehyde,'5 or formaldehyde.'9 Somestudies have used aqueous extracts of cigarettesmoke obtained by bubbling the smoke througha buffer, with or without filtering to removesuspended particulates,20 while otherresearchers have focused on free radical pro-duction arising from chemical reactions withinthe cigarette smoke.2'

Overall, owing to the variability in experi-mental methodologies (including the type of"cigarette smoke") used, interstudy compari-sons may be difficult to interpret. It is well tokeep this in mind when reading this review.

Department ofAnatomy,PhysiologicalSciences, andRadiology,College ofVeterinaryMedicine,North CarolinaState University,Raleigh, NorthCarolina 27606,USAJ A DyeK B Adler

Center forEnvironmentalMedicine & LungBiology,University of NorthCarolina,Chapel Hill, NorthCarolina, USAJ A Dye

Reprint requests to:Dr KB Adler.Received 18 November1993Returned to authors16 February 1994Revised version received8 April 1994Accepted for publication18 April 1994

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Dye, Adler

Component cells of airway epitheliumThe airway epithelium is a mosaic of at leasteight principal cell types, the exact compositionof which may vary depending on the level of theairway and the species of interest. Ciliatedepithelial cells and goblet cells form most of theluminal surface of the larger airways, and theyare joined by tight junctions to form a relativelyimpermeable barrier to material from the lumi-nal surface.22 The tight junctions are also im-portant for polarised secretion and the selectivepermeability exhibited by airway epithelium.Other epithelial cell types (dependent on thespecies and airway level) include basal cells,neuroendocrine cells, Clara cells, serous cells,small mucous granule cells, brush cells, and avariety of intermediate cell types.23 The nasalairways comprise a similar spectrum of cellstogether with several unique types required forolfaction (olfactory sensory and basal cells andthe sustentacular cell).23 Although the effects ofcigarette smoke on nasal airways have been lessextensively studied, significant exposure mayresult from nasal exhalation. Moreover, nasalepithelium is the first respiratory epithelial sur-face exposed to environmental tobacco smoke.Airway epithelial surfaces are covered by a

thin layer of mucus consisting of sol and gelfractions. In addition, mast cells or occasionallymphocytes are found within the airway epi-thelium or lumen, although more commonly inthe submucosal layer.22 The epithelium alsocontains an abundance of nerve fibres whosereceptors (irritant receptors, stretch receptors)run circumferentially around the luminal cellsand respond to stimuli such as gases, smoke, orantigens.22 This review will focus on the epithe-lial cells that line the luminal surfaces of theconducting (non-gas exchange) airways. Itshould be kept in mind, however, that cigarettesmoke-induced alterations in these cells mayresult in altered function of other airway epi-thelial components. For example, the cigarettesmoke-induced increase in mucosal permea-bility may also allow increased access of theepithelial nerve receptors and mast cell popula-tions to irritant or antigenic stimuli.22

Histological changes in response tocigarette smokeLaboratory animals exposed to cigarette smokedevelop histological changes in both the upperand lower airways (table 1). Hyperplasia andsquamous metaplasia of the respiratory epithe-lium of the dorsal nasal turbinates was observedin rats following exposure to sidestream cigar-

Table 1 Histological changes of the respiratory tractassociated with exposure to cigarette smoke

Airway epithelial hyperplasiaNasal respiratory epithelial hyperplasiaAirway mucous cell hyperplasiaAirway submucosal gland hypertrophyIntraluminal, mucosal, and parenchymal inflamnmationEmphysemaHyperplasia of pulmonary neuroendocrine cellsReduction of pulmonary lymphoid cells (for example, BALT)Squamous metaplasia of airway and nasal epitheliumPreneoplastic and neoplastic lesions

ette smoke for 90 days.24 Mice inhaling cigarettesmoke developed basal cell hyperplasia andsquamous metaplasia of the nasal cavity, as wellas hypertrophy of Clara cells.25 In a cigarettesmoke-induced model of "bronchitis" exposureof Sprague-Dawley rats to smoke (25 cigarettes/day for 14 days) increased epithelial thickness atthree of the four airway levels assessed due to a100-400% increase in the number of secretorycells.26 Initial changes included basal cell pro-liferation accompanied by mucous metaplasiaof surface epithelial serous cells, and prolifera-tion of the newly formed mucous cells. Theacidic glycoprotein-containing secretory cellswere dramatically increased in number, whilethe neutral glycoprotein-containing secretorycells were decreased. Histological changes inairways of patients with chronic bronchitis alsoincluded mucous cell hyperplasia and hyper-trophy of submucosal glands with a shift toacidic, sialidase resistant, intracellular glyco-proteins.When non-steroidal anti-inflammatory drugs

or corticosteroids were given concurrently withsmoke exposure in a rat model of bronchitis,smoke-induced mucous cell hyperplasia wasvariably inhibited, depending on the drug andlevel of the airways examined.27 Additionalstudies found that after cigarette smoke expos-ure in the rats the time required for secretorycell hyperplasia to resolve was shorter in largerthan smaller airways - for example, trachea ninedays; distal bronchioles up to 84 days.28 Treat-ment with non-steroidal anti-inflammatorydrugs during the recovery period hastened thereturn to normal epithelial architecture in thesmaller airways (to 4-9 days) but had no effecton tracheal recovery.29 Treatment of rats with1% N-acetylcysteine during the recoveryperiod also reduced the time for secretory cellnumbers to return to normal.30 Furthermore,concurrent administration of N-acetylcysteinewith cigarette smoke exposure inhibited theinitial increase in the number of acidic glyco-protein-containing secretory cells, but had littleeffect on numbers of cells containing neutralglycoproteins.26

Balansky et alP exposed Sprague-Dawleyrats to cigarette smoke once daily for 40 daysand observed dramatic histological changes interminal airways, including severe neutrophilicinfiltration of the mucosa, hyperplastic andmetaplastic lesions, and micropapillomatousfoci. Concurrent administration of N-acetyl-cysteine effectively prevented these changes.Studies in humans have also shown signific-antly increased numbers of total inflammatorycells and polymorphonuclear leucocytes inwalls of membranous bronchioles in smokers.This response does not subside following smok-ing cessation as both current and ex-smokershad similar numbers and types of inflammatorycells in their airway walls.'2

Inhaled cigarette smoke also induces pre-neoplastic changes in rat tracheal epithelialcells, lesions influenced by dietary deficiencies.In vitamin A (retinoic acid) deficient rats cigar-ette smoke caused epidermoid metaplasia char-acterised by stratified, keratinised, and squa-mous epithelial changes,3 and focal areas of

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squamous metaplasia including extensive squa-mous metaplasia of the larynx.34 Conversely,when neonatal rat tracheas in organ culturewere treated simultaneously with an experi-mental retinoid compound (Ro 15-0778),lesions associated with cigarette smoke conden-sate (hyperplasia, metaplasia, loss of secretoryactivity, and ciliary function) were prevented.35To our knowledge similar studies have not beenperformed in humans, although several invest-igators are evaluating a potential use for retin-oids in preventing or reversing metaplasticchanges in airway epithelium at the molecularlevel. Much of this work has been done with invitro models.

Effects of cigarette smoke on epithelialbarrier functionIn airway epithelia tight cell-cell and cell-matrix contact allows for maintenance of arelatively impermeable (or selectively perme-able) barrier between the airway lumen andunderlying submucosal and vascular compon-ents of the respiratory system. Owing in part tothis barrier, specific transport mechanisms ofairway epithelia can regulate chloride secretionor sodium absorption and precisely maintainthe amount and composition of respiratory tractlining fluid. Alterations in this fluid occur whennormal airway epithelial function is disruptedby disease states such as cystic fibrosis, orexogenously derived perturbation such as cigar-ette smoking. Although not specific for cigarettesmoking, processes that alter integrity of theairway epithelium (especially that of the alveo-lar spaces) are associated with an increased rateof 99mTc-DTPA clearance. Using 99mTc-DTPAthoracic scintigraphy has confirmed that lungsof smokers are more permeable than those ofnon-smokers.36 Increased epithelial permea-bility occurs at an early stage in asymptomaticor neophyte smokers.37 Rapid clearance is pro-moted by increased lung volumes and de-creased surfactant secretion; however, the exactmechanism(s) for increased 99mTc-DTPA clear-ance in these states is unknown.38

Cigarette smoke-induced changes in 99mTc-DTPA clearance could reflect alterations inpermeability of pulmonary vasculature,39 alveo-lar permeability, and/or altered integrity of theconducting airways. Cigarette smoke increasesendothelial permeability by its effects on cyto-skeletal elements as shown in porcine pulmon-ary artery preparations,. tachykinin release inrat nasal passageways,' and cation influx in ratairway vasculature.41 Following cigarette smokeexposure in guinea pigs changes in alveolarpermeability were associated with type I cellinjury.42 In rabbits acute cigarette smoke expos-ure was associated with increased 99"Tc-DPTAclearance, histological focal alveolar oedemaand haemorrhage, but no ultrastructuralchanges in the alveolar capillary membrane.43Increased 99mTc-DPTA clearance occurred inrats exposed to cigarette smoke, but light mic-roscopically detectable abnormalities were notseen in the lung parenchyma.44

Increased permeability of the airway epithe-lium to large molecular weight molecules (for

example, dextran45) has been demonstrated inguinea pigs following inhalation of cigarettesmoke, and appeared to be linked to damage toepithelial tight junctions.46 Bronchial epithelialcells exhibited increased detachment followingapplication of proteases to their apical surfacewhen cultures were first exposed to cigarettesmoke extract (also on their apical surface).47These results suggest that an intact airwayepithelium is an important barrier against pro-teases released from intraluminal inflammatorycells.Exposure ofprimary hamster tracheal epithe-

lial cells to non-toxic concentrations of cigarettesmoke extract inhibited intercellular communi-cation across gap junctions.48 In primary chickembryo hepatocytes cigarette smoke condensateinduced a greater than 60% reduction in gapjunction numbers.49 Furthermore, the numberof gap junctions and the rate of gap junctioncommunication was inhibited by cigarettesmoke condensate from tobacco-burning, butnot tobacco-heated, cigarettes in cultured rathepatic epithelial cells and human fibroblasts.50Taken together, these studies indicate that

cigarette smoke and/or many of its componentscan have a number of deleterious effects onintercellular communication and epithelial per-meability. These alterations can play a part inthe development of chronic respiratory dis-eases.

Alterations in airway secretions andciliary clearance apparatusIt is beyond the scope of this report to reviewthe structure and synthesis ofmucins and struc-ture and function of cilia. Readers are referredto several excellent review articles in this area.5'Briefly, mucociliary clearance is dependent onthe coordinated activities of (a) normal ciliarystructure and function, (b) appropriate quantit-ies and physicochemical properties of mucus,and (c) appropriate quantity (depth) of pericili-ary lining fluid. Alteration or dysfunction ofanyone of these components may result in reducedefficiency of the entire mucociliary clearanceescalator.52

Cigarette smoke has profound effects onmucociliary function but the underlyingmechanisms have not been elucidated. Studieshave been hampered by: (a) complex interrela-tionships between various components of themucociliary apparatus; (b) the complexity of thecigarette smoke mixture; (c) the fact that studieson the time course of particle clearance depend,not only on mucociliary velocity, but on initialparticle distribution and deposition patterns;53and (d) the fact that acute effects of cigarettesmoke in naively exposed subjects do not neces-sarily reflect those found in chronically exposedsubjects.53 Effects of cigarette smoke on muco-ciliary function have been reviewed pre-viously.52

Environmental cigarette smoke exposure hasbeen implicated increasingly in the develop-ment of upper respiratory tract infections andotitis media, especially in children.54 Cigarettesmoke and other indoor air pollutants have beenshown to alter upper airway mucociliary func-

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tion. Nasal mucociliary clearance in asympto-matic smokers was longer than in lifelong non-smokers, although no differences were detectedin the mean nasal ciliary beat frequency.55 Con-versely, acute exposure to cigarette smoke in therabbit was associated with increased mucocili-ary activity of the maxillary sinuses. Theseeffects, however, were mediated reflexly viaNK1 receptor stimulation by tachykininsreleased secondarily to irritant effects of cigar-ette smoke on sensory afferent nerves in theupper airways.56

Tracheal mucus from asymptomatic smokersis increased in both volume and water content,with a lower total solid content than mucus

from non-smokers. This mucus causedincreased mucociliary "clearability" in frogpalate transport assays.57 Significant elevationsof a macrophage-derived mucus secretagogue(MMS-68) have been detected in the bron-choalveolar lavage fluid of cigarette smokers.58Tracheal potential differences, a measurementof transepithelial electrical potential differenceused to assess ion permeability and ion trans-port across respiratory epithelia, were reducedin chronic cigarette smokers.59Under similar airway deposition patterns

inner lung zone clearance of particles (asassessed by gamma camera imaging) was signi-ficantly slower in asymptomatic smokers thanin age matched non-smoking controls.60 Alveo-lar deposition after 24 hours, however, was

reduced, suggesting that smokers have a greaterproportion of small conducting airways capableof mucociliary clearance.6" These findings maybe related to smoking-induced changes in bron-chiolar secretory cells where secretion of cross-linked mucus glycoproteins is enhanced,increasing the efficiency of mucus-cilia coup-

ling. Non-smokers have poorer mucociliary de-fence capabilities in their more distal peripheralairways, which would not be necessary unlesschronic insults arose. In these asymptomaticsubjects cigarette smoke-associated alterationsin mucus may be beneficial. Inhalation ofsmoke from a single cigarette acutely (andreversibly) decreased the electrical potentialdifference across canine tracheal epithelium.62Both in vivo and in vitro acute exposure ofcigarette smoke in the dog inhibited active iontransport (chloride secretion) by tracheal epi-thelium.62 Chronic smoke exposure in the dog(10 cigarettes/day for 10 months) causedpersistently increased tracheal mucus flux.63

In vivo and in situ animal studies have beenused to dissect the reflex secretory responsesinduced by cigarette smoke. Reflexes initiatedby nervous receptors in the airways normallyaugment mucus secretion in response to airwayinsult. Absorbed nicotine, however, bypassesits usual reflex circuits by directly stimulatingganglion cells.64 In guinea pigs acute inhalationof low doses of cigarette smoke stimulated air-way goblet cell secretion by activating choliner-gic nerves (via parasympathetic ganglion stimu-lation) whereas exposure to high doses of thevapour phase of cigarette smoke stimulatedcapsaicin-sensitive sensory nerve endings.65 Inrats both control and previously exposed"bronchitic" animals showed exhibited tran-

Dye, Adler

sient increases in fucose (a mucus marker) sec-retion when cigarette smoke was blown throughtheir laryngotracheal segments in situ.66 In thecat in situ studies have indicated the complexityof reflex responses involved; cigarette smokepassed directly into the feline trachea segmentstimulated mucin secretion, while smoke passeddirectly into the lower airways stimulated secre-tion in the lung segment. If cigarette smoke wasfirst passed through the larynx, however, noaugmentation occurred. It seems necessary fornicotine to be absorbed either directly into thetracheal segment or into the blood (via thealveolar spaces) for the autonomic gangliainnervating the airway submucosal glands to bestimulated. This reflex pathway predominatesover that of airway irritant reflexes.67

Nicotine was a powerful mucus secretagoguewhen applied to ferret tracheal segments invitro.68 Exposure of organ cultures of rat tra-chea to cigarette smoke condensate induced lossof secretory activity and ciliary function,35 andexposure of rat tracheal explants to varyingamounts of cigarette smoke for 10 minutesinduced dose-related blebbing of the apicalmembrane and loss of cilia.69 The cigarettesmoke component acrolein reduced ciliary beatfrequency in cultured bovine bronchial epithe-lial cells,70 while acetaldehyde - another majorcomponent of tobacco smoke - impaired ciliaryfunction and beat frequency by inhibiting cili-ary dynein ATPase activity and binding tociliary proteins critical in the functioning ofdynein and tubulin.7'Thus, cigarette smoke and/or many of its

components can have direct effects on the secre-tory and transport functions of airway epithelialcells. Obviously such alterations can play animportant part in the pathogenesis of chronicairway disease - for example, decreased muco-ciliary clearance can result in airway obstruc-tion and increased susceptibility to microbialinfection.

Influences of cigarette smoke on airwayepithelial regulatory functionsAIRWAY NEUROPEPTIDE REFLEX RESPONSESAND BRONCHOCONSTRICTIONAirway reflex responses to irritants such ascigarette smoke are important in mediatingchanges in mucus secretion and these pathwaysoften involve release of tachykinins, a family ofneuropeptides including substance P, neuro-kinin A, and neurokinin B. When released fromsensory nerve endings in the airways tachy-kinins act on various receptors eliciting a typicalpattern of response. These collective effects -often referred to as "neurogenic inflammation"- include mucus hypersecretion, smoothmuscle contraction, increased airway mucosalplasma extravasation (associated with increasedvascular permeability), increased neutrophiladhesion, and cough.72 Tachykinins are nor-mally rapidly hydrolysed by the membrane-bound metalloenzyme, neutral endopeptidase(NEP), which is widely distributed in the air-ways. Excessive release of tachykinins, how-ever, decreases the capacity of NEP enzymaticdegradation, or a combination of these effects



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Effects of cigarette smoke on epithelial cells of the respiratory tract

may result in exaggerated neurogenic res-

ponses.Cigarette smoke exposure stimulated prim-

ary afferent sensory nerves in rats, elicitingtachykinin release and resultant mucosaloedema of tracheal tissue.73 Chemical irritantsin the vapour phase of cigarette smoke areprimary elicitors of the permeability response.74Inhalation of cigarette smoke in guinea pigs alsoaugments airways responsiveness to inhaledsubstance P and capsaicin,74 effects associatedwith decreased airway NEP activity.75 Super-natants from bovine bronchial epithelial cellsexposed to tachykinins exhibited increased neu-trophil chemotactic activity,76 and direct pre-treatment of bovine bronchial epithelial cellswith substance P significantly increased adher-ence of cocultured neutrophils.77Pulmonary neuroendocrine cells - for ex-

ample, neuroepithelial bodies and small granulecells - are a poorly understood group of epithe-lial cells in the airways, and cigarette smokinghas been associated with this hyperplasia andvariable increases in respiratory tract concen-trations of the bombesin-related peptides.78Bombesin-related peptides are a family ofneuropeptides similar to amphibian bombesin.They are present in several human body sys-tems including the respiratory tract where theyhave a role(s) in immunological lung func-tions.79 They exert chemoattractant activity formonocytes, mitogenic activity for bronchialepithelial cells, and bronchoconstrictive activ-ity. These peptides are involved in cigarettesmoke-associated lung inflammation, fibrosis,and/or airway obstruction,79 and function asessential autocrine factors for many small celllung cancers. Since cigarette smoke inactivatesNEP, and NEP normally hydrolyses bombesin-related peptides, it has been proposed thatdecreased airway NEP activity may also becausally related to the development of thesecarcinomas.80

Nitric oxide exhibits potent relaxing activityin both canine and guinea pig airways.8' Unsti-mulated bovine bronchial epithelial cells inculture are capable of converting L-arginine toL-citrulline, one of the biosynthetic pathways ofnitric oxide.82 Moreover, exposure of the epi-thelial cells to cigarette smoke extract preventedthis conversion, as did treatment of the cellswith competitive inhibitors of nitric oxide syn-thase.82 Competitive inhibitors of nitric oxidesynthase also decrease ciliary beat frequency incultured bronchial epithelial cells,83 and the freeradical reactant product of nitric oxide and lowmolecular weight thiols can form S-nitrosothioladducts which have potent relaxation effects onairway smooth muscle.84

Finally, another potential cause of smoke-induced airway obstruction could be the devel-opment of airway inflammation and associatedincreases in release of cytokines. For example,guinea pig tracheas cultured with inflammatorycytokines such as IL-8 and TNFa demon-strated increased synthesis of endothelin-1, a

potent bronchoconstrictor.85

AIRWAY INFLAMMATIONPerturbations of the airway epithelial cell bar-

rier induced by cigarette smoke may lead toadverse changes resulting in airway inflamma-tion (table 2). Specific mechanisms involved inthis inflammation include: (a) increased syn-thesis and/or release of inflammatory mediators(for example, arachidonic acid metabolites,chemotactic agents) or, alternatively, decreasedsynthesis of protective mediators (for example,chemotactic factor inactivators); (b) synthesis ofproinflammatory cytokines; (c) modulation ofcell adhesion molecules; and (d) modulation ofimmunoregulatory processes.

Cigarette smoke induces an acute inflamma-tory reaction in the airways and lung paren-chyma. Peripheral leucocytosis86 and increasesin bronchoalveolar lavage neutrophil and totalinflammatory cell counts have also been demon-strated in cigarette smokers.87 In one study bothcurrent and ex-smokers had increased totalinflammatory cells and neutrophils in the wallsof their membranous bronchioles comparedwith non-smokers,32 and they also had similarnumbers and types of airway inflammatory cellspresent regardless of concurrent emphysema-tous changes.3288Airway epithelial cells are an important

source of inflammatory mediators9 since re-sponses to various stimuli may involve epithe-lial release of chemotactic activity for leuco-cytes.89 Cigarette smoke has proved to be a"reliable" stimulus for inducing release of suchchemotactic activity, although the specificmediators released vary among species in bothin vivo and in vitro studies. Exposure of youngnon-smoking humans to environmental tobaccosmoke for three hours promoted systemic prim-ing of neutrophils and increased circulatingneutrophil counts, neutrophil chemotaxis, andneutrophil release of oxidants upon stimula-tion.90 Similarly, human bronchial epithelialcell cultures exposed to smoke extract releasesignificantly greater neutrophil chemotactic ac-tivity than controls.82 Nitric oxide appeared toplay a part in this response as pretreatment ofthe cultures with a nitric oxide synthase inhibi-tor (L-NMMA) abrogated this increase, whileaddition of L-NMMA to supernatants failed toinhibit neutrophil chemotactic activity.82At concentrations comparable to levels

observed in the plasma of smokers nicotineappeared to enhance the neutrophilic responseto other chemotactic peptides.91 At higher con-centrations, however, nicotine inhibited theneutrophil chemotactic response and sponta-

Table 2 Potential mechanisms of epithelial cells servingas effector cells

Neutral endopeptidase enzymatic degradation of tachykininsProduction of bombesin-related peptidesProduction of nitric oxideProduction of endothelin-IMajor histocompatibility complex class II antigen expressionProduction of arachidonic acid metabolites (for example,

prostaglandins, thromboxanes, leukotrienes,hydroxyeicosotetraenoic acids)

Production of chemotactic agentsProduction of chemotactic factor inactivatorsCytokine production (for example, GM-CSF, G-CSF, IL-6,

IL-8)Cell adhesion molecule changes (for example, ICAM-1)Production of fibronectin and other extracellular matrix

molecules

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neous migration.92 Nicotine pretreatment ofmice appeared to enhance neutrophil influxtowards the "source of inflammation" when thechemotaxin, zymosan-activated serum, wasinjected into the pleural space.92

Smoke-induced recruitment of neutrophilswas complement-dependent in mice: C5-suffi-cient mice, but not C5-depleted mice, exposedto cigarette smoke had increased neutrophilchemotactic activity in their bronchoalveolarlavage fluids.93 Others suggest that the mechan-ism of neutrophil influx into the lungs relates tosmoke-induced loss of functional activity ofchemotactic factor inactivator (CFI). CFI nor-mally inhibits C5a-directed neutrophil chemo-taxis by binding to GcGlobulin, an essentialcochemotaxin of C5a.94 While specific smoke-induced effects on other airways or alveolerprotease inhibitors remain largely unknown,cigarette smoke inactivation of a-protease inhi-bitor is a contributing factor in the developmentof smoking-related emphysema.95Airway epithelial cells contain both linoleic

acid and arachidonic acid, which are availablefor metabolism and release via oxidative path-ways and are capable of metabolising arachido-nic acid to prostaglandins, thromboxanes, leuk-otrienes, and hydroxyeicosotetraenoic acids(HETEs), although the exact profile of eicosa-noids is dependent on the species of origin andthe nature of the stimulus - for example, ozone,nitrogen dioxide.9697 Since these eicosanoids areassociated with effects ranging from enhancedmucus secretion to smooth muscle contractionand inflammatory cell chemotaxis their releasefollowing exposure to cigarette smoke has alsobeen evaluated. In humans cigarette smokingcauses increased urinary excretion of the 2,3-dinor metabolites of thromboxane A2, but notprostacyclin (PGI),98 and reduces salivary con-centrations of PGE2, PGF2,,, leukotrienes, and12-HETE.99 Bronchoalveolar lavage fluidobtained from Wistar rats exposed to cigarettesmoke contained increased concentrations of15-HETE but not thromboxane B2.'00 Conver-sely, bronchoalveolar lavage fluid from guineapigs exposed to acrolein (a low molecularweight aldehyde found in cigarette smoke) hadincreased concentrations of both PGF2,, andthromboxane B2.'0' In vitro exposure of bovinetracheal epithelial cells to non-cytotoxic con-centrations of acrolein caused increased releaseof PGE2, PGF2 ,, 6-keto-PGFI,,, 12-HETE, and15-HETE. Exposure of isolated rat trachealsegments to cigarette smoke extract elicited abiphasic effect on muscarinic-stimulated eico-sanoid synthesis: low concentrations poten-tiated production while higher concentrationsinhibited this response.'02 Exposure of caninemast cells to cigarette smoke solution inhibitedPGD2 production but induced increased releaseof the preformed mediators, histamine andtryptase.'03

Research over the last decade has expandedour knowledge of cytokines and their networksand their role in inflammatory responses of therespiratory tract. Airway epithelial cells them-selves are now known to be capable of synthe-sising, releasing, and/or upregulating produc-tion of these locally acting mediators. Analysis

of conditioned medium from human bronchialepithelial cells in primary culture demonstratedthe presence of GM-CSF, G-CSF, and IL-8.'°4The presence of GM-CSF and G-CSF in theconditioned media caused increased in vitrosurvival of cultured peripheral blood neutro-phils.lc4 IL-8 is the major cytokine of the hu-man nasal epithelium,'05 although conditionedmedia from human nasal epithelial cell culturesalso contained GM-CSF, G-CSF, and IL-6.'06There are too few data available on the influ-ence of cigarette smoke on cytokine productionby airway epithelial cells, but exposure of hu-man alveolar epithelial cells to a phenol-richglycoprotein present in cigarette smoke con-densate was associated with increased synthesisof IL-1 and IL-6. Exposure also elevatedsteady state levels of mRNAs for IL-1, IL-6,and platelet derived growth factor (PDGF-Aand PDGF-B) as detected by in situ nucleicacid hybridisation.'07 As assessed by bioassays,cigarette exposure of cultured human andguinea pig alveolar macrophages decreased IL-7 and TNF activity.'08 Additionally, lipopoly-saccharide-stimulated alveolar macrophagesfrom smokers caused less IL-1 and IL-6production than alveolar macrophages fromnon-smokers.'09 This may be important for theincreased susceptibility of smoking patients torespiratory infections, and to the decreasedincidence of immune-mediated pulmonary dis-eases such as sarcoidosis in smokers.' °Human bronchial epithelial cells have

recently been shown to express the a2-6 integ-rins, molecules which interact with many extra-cellular matrix components. Cultured humanrespiratory cells also express intercellular adhe-sion molecule 1 (ICAM-1) on their surfaces.Adherence of neutrophils to airway epithelialcells via ICAM-1 may be an important factor ininflammatory airway diseases."' The processesby which neutrophils migrate to sites of airwayinflammation are complex and beyond thescope of this report. Briefly, however, asreviewed recently,"2 initial steps of neutrophilrecruitment involve a process known as "roll-ing" whereby neutrophils begin to decelerateand attach to the endothelial surface of post-capillary venules at or near sites of tissue injuryor inflammation. Adhesion molecules of theselectin family (P-, E-, and L-selectin) areessential components in this process. Neutro-phils subsequently arrest and spread over theendothelial cell surface via interactions betweentheir P2-integrins (CDl la/18 and CDl lb/18)and endothelial cell ICAM-1. Once firmlyattached, leucocytes migrate through vesselwalls, extracellular matrix components, andbetween normally adherent epithelial cells fol-lowing chemotactic and/or haptotactic gradi-ents. Migration requires careful regulation ofproteolytic enzyme secretion and transforma-tion of the cell into a deformable, motile state.Once near or at the site of airway injury orinflammation, leucocyte retention involvescritical concentrations of specific cytokine(s) -

for example, GM-CSF - and continued inter-action with epithelial cell adhesion molecules.Interestingly enough, proinflammatory cyto-kines - for example, IL-1, TNFoa - increase cell

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surface expression of ICAM- 1 and neutrophiladhesion to tracheal epithelial cells in vitro."'Selective induction of human tracheal ICAM-1expression in human tracheal epithelial cells hasalso been shown in response to interferon ytreatment.

Cigarette smoke elicits a number of neutro-phil migratory and cell adhesion changes. Neu-trophil transit time through the human pul-monary vasculature is prolonged by inhalationof cigarette smoke."2 Studies in rabbits haveshown that smoking-induced neutrophil reten-tion in pulmonary vasculature occurs withoutcorresponding changes in pulmonary haemo-dynamics."3 In hamsters acute exposure tomainstream smoke for five minutes provokedneutrophil rolling and subsequent adhesion tothe endothelium of both postcapillary venulesand arterioles. Adhesion steps were mediatedvia 5-lipoxygenase metabolites of arachidonicacid (leukotrienes)."'4 In vitro exposure ofneutrophils to both the whole particulate andvapour phase of cigarette smoke reduced thedeformability (hence migratory capability) ofneutrophils via effects on the actin componentof their cytoskeleton."15 Also, plasma myeloper-oxidase concentrations are elevated immedi-ately after exposure to cigarette smoke whichsuggests that cigarette-induced lung damage isrelated to activation of leucocytes still withinthe pulmonary capillary bed."3 Further evid-ence is provided by intravascular neutrophils incertain lung regions of rabbits exposed tosmoke which showed increased expression ofCD 1 1/CD 18 coincident with decreased L-selec-tin expression."16 After subacute (two week)exposure rats did not show altered endothelialneutrophil adhesion compared with sham-exposed animals; however, after treatment withcapsaicin they had more vascular adherent neu-trophils, suggesting that cigarette smoke poten-tiates neutrophil adhesion in association withneurogenic airway inflammation. '" Exposure ofmonolayers of bovine bronchial epithelial cellsto cigarette smoke extract significantlyincreased adherence of both cocultured neutro-phils and mononuclear cells."8 Peripheral bloodneutrophils exposed to cigarette smoke in vitroand then cocultured with alveolar epithelialcells demonstrated decreased adherence whichdid not increase after stimulation withf-Met-Leu-Phe."9As mentioned previously, cigarette smoking

is associated with a decrease in certain immunemediated pulmonary diseases"0 while smokingand/or exposure to environmental tobaccosmoke has been associated with increased res-piratory infections including sinusitis, otitismedia, bronchitis, and pneumonia,5 conditionspresumably related to alterations in immunefunction.'20 Immunological effects induced bycigarette smoke include reduction of bronchusassociated lymphoid tissue (BALT), decreasedimmunoglobulin concentrations due to sup-pression of B cell antibody production (exceptfor IgE, which is increased), decreased helperT cell numbers, decreased natural killer cellactivity, and increased circulating soluble IL-2receptors.'2012' Infections asociated with cigar-ette smoke may be related to effects such as

decreased mucociliary clearance of inhaledinfectious agents. Other smoking-relatedimmunological effects on airway epithelialfunction could involve alterations in the expres-sion of major histocompatibility complex classII antigen (MHC class II) or alterations in thefunction of airway dendritic cells. Expression ofMHC class II antigens was increased in bovinebronchial epithelial cells exposed to super-natants from activated lymphocytes.'22 Antigenpresenting functions of pulmonary dendriticcells (which typically express ICAM-1) aredownregulated via interactions with residentalveolar macrophages.

Repair of injured areas of airway epithelium(resulting from either direct cigarette smoke-induced injury or as a consequence of airwayinflammatory processes) may be impaired byongoing cigarette smoke exposure. Cigarettesmoke degrades hyaluronic acid,'23 decreasesfibronectin release from cultured bovine bron-chial epithelial cells,'24 and delays migration ofbronchial epithelial cells to fibronectin.'25The airway epithelial cell therefore has the

potential to act as an inflammatory cell, re-sponding to smoke/and or many of its compon-ents by releasing a number of humoral andinflammatory mediators that may enhance theinflammatory reaction in the airways and con-tribute to the pathogenesis of chronic disease.The role of airway epithelial cells as potentialeffector cells in the response to smoke or manyother insulting or injurious agents is a researcharea that has received much recent attention,and it is possible that these cells can produce anumber of other as yet unidentified compoundsthat can contribute to airway inflammation.

Cigarette smoke combined with otherpulmonary insultsSynergistic effects of cigarette smoke with otherrespiratory insults have been reported - forexample, a synergistic effect of asbestos expos-ure and cigarette smoke in bronchogenic carci-noma.'26 A mechanism of this synergy suggeststhat both deleterious agents provoke generationof reactive oxygen species in the airways.'27 Inguinea pigs exposure to cigarette smoke com-bined with intratracheal instillation of amositeasbestos fibres resulted in increased penetrationof the asbestos fibres into the airway walls.'28Cigarette smoke exposure also impairs clear-ance of amosite asbestos fibres (particularly theshorter fibres) from both alveolar macrophages(30-fold increase in fibre number) and pulmon-ary tissue (eightfold increase). 129 Excised rattracheal segments exposed to cigarette smokefollowed by amosite asbestos have increasedepithelial uptake of the fibres, and uptake wasstill enhanced wher, smoke exposure precededasbestos treatment by up to 48 hours.'30 Again,reactive oxygen species played a part in smoke-mediated fibre transport into the tracheal epi-thelium."' Cigarette smoke exposure of tra-cheal epithelial explants also directly enhanceduptake of inert dust - that is, non-fibroustitanium dioxide, talc, and fibrous silicon car-bide - while treatment with scavengers of reac-tive oxygen species only blocked uptake of someof these particles.'32 Finally, exposure to cigar-

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ette smoke has also been associated with poten-tiation of pulmonary injury following instilla-tion of bleomycin,133 irradiation-inducedpneumonitis,'34 and ozone inhalation.'35

ConclusionsCigarette smoke and many of its individualcomponents, both gaseous and particulate, cangenerate various lesions in epithelial cells of theairways. Interactions between these stimuli andairway epithelial cells are just beginning to beelucidated. Although studies of cigarettesmoke-induced effects on individual cells of theairway epithelium are exceedingly useful foreliciting underlying mechanisms of respiratoryinjury and disease, the overall respiratory sys-tem response depends ultimately upon the inte-grated action of all effector cell populations withtheir corresponding target cells. To fullyunderstand how defence mechanisms withinthe respiratory system attempt to interveneagainst cigarette smoke while attempting torepair previous smoke-induced damage, theseinteractions of airway epithelial cells with otherhost defence/repair mechanisms must be morecompletely understood.

1 Fletcher CM, Peto R. The natural history of chronic airflowobstruction. BMJ 1977;1:1645-8.

2 Gerrard JW, Cockcroft DW, Mink JT, Cotton DJ, Poo-nawala R, Dosman JA. Increased nonspecific bronchialreactivity in cigarette smokers with normal lung function.Am Rev Respir Dis 1980;122:577-81.

3 Chilmonczyk BA, Salmun LM, Megathlin KN, NeveuxLM, Palomati GE, Knight GJ, et al. Associations betweenexposure to environmental tobacco smoke and exacer-bations of asthma in children. N Engl J Med1993;328: 1665-9.

4 Hoidal JR, Niewoehner DE. Lung phagocyte recruitmentand metabolic alterations induced by cigarette smoking inhumans and in hamsters. Am Rev Respir Dis1982;126:548-52.

5 Marcy TW, Merrill WW. Cigarette smoking and respira-tory tract infection. Clin Chest Med 1987;8:381-91.

6 International Agency on the Research of Cancer. IARCMonograph on the Evaluation of the Carcinogenic Risks ofChemicals to Humans: Smoking. Lyon, France: IARC,1986;38:199-243.

7 Muscat JE, Wynder EL. Tobacco, alcohol, asbestos, andoccupational risk factors for laryngeal cancer. Cancer1992;69:2244-51.

8 Brinton LA, Blot WJ, Becker JA, Winn DM, Browder JP,Farmer JC Jr, et al. A case-control study of cancers of thenasal cavity and paranasal sinuses. Am J Epidemiol1984;1 19:896-906.

9 Cohn LA, Adler KB. Interactions between airway epithe-lium and mediators of inflammation. Exp Lung Res1992;18:299-322.

10 Brunnemann KD, Hoffmann D. Analytical studies ontobacco-specific N-nitrosamines in tobacco and tobaccosmoke. Crit Rev Toxicol 1991;21:235-40.

11 US Department of Health, Education and Welfare. Smok-ing and health. In: A Report of the Surgeon General.DHEW Publ. No. (PHS) 79-50066 (eds). 1988, 5-11.

12 Proctor CJ, Smith G. Considerations of the chemical com-plexity of ETS with regard to inhalation studies. ExpPathol 1989;37:164-9.

13 Lofroth G. Environmental tobacco smoke: overview ofchemical composition and genotoxic components. MutatRes 1989;222:73-80.

14 Kilburn KH. Particles causing lung disease. Environ HealthPerspect 1984;55:97-109.

15 Utell MJ. Particulate air pollution and health. New evid-ence on an old problem (editorial). Am Rev Respir Dis1993;147:1334-5.

16 Guerin MR, Jenkins RA, Tomkins BA. The chemistry ofenvironmental tobacco smoke: composition and measurement.Chelsea, MI: Lewis Publishers, 1992.

17 Leikauf GD, Leming LM, O'Donnell JR, Doupnik CA.Bronchial responsiveness and inflammation in guinea pigsexposed to acrolein. J Appl Physiol 1989;66:171-8.

18 Sisson JH, Tuma DJ, Rennard SI. Acetaldehyde-mediatedcilia dysfunction in bovine bronchial epithelial cells. Am JPhysiol 1991;260:L29-36.

19 Godish T. Formaldehyde exposures from tobacco smoke: a

review. Am J Public Health 1989;79:1044-5.20 Rickard KA, Taylor, Rennard SI. Observations of develop-

ment to detachment of cultured bovine bronchial epithe-

Dye, Adler

lial cells in response to protease treatment. Am J RespirCell Mol Biol 1992;6:414-20.

21 Church DF, Pryor WA. Free-radical chemistry of cigarettesmoke and its toxicological implications. Environ HealthPerspect 1985;64:111-26.

22 Hogg JC. Bronchial mucosa permeability and its relation-ship to airways hyperreactivity. Eur J Respir Dis1982;122(Suppl): 17-22.

23 Harkema JR, Mariassy A, St. George J, Hyde DM, PlopperCG. Epithelial cells of the conducting airways. A speciescomparison. In: Farmer SG, Hay DWP, eds. The airwayepithelium. Physiology, pathophysiology, and pharmacology.New York: Marcel Dekker, 1991:3-39.

24 von Meyerinck L, Scherer G, Adlkofer F, Wenzel-HartungR, Brune H, Thomas C. Exposure of rats and hamsters tosidestream smoke from cigarettes in a subchronic inhala-tion study. Exp Pathol 1989;37:186-9.

25 Takahashi A, Iwasaki I, Ide G. Effects of minute amountsof cigarette smoke with or without nebulized N-nitroso-N-methyurethane on the respiratory tract of mice. Jpn JCancer Res 1985;76:324-30.

26 Rogers DF, Jeffery PK. Inhibition by oral N-acetylcysteineof cigarette smoke-induced "bronchitis" in the rat. ExpLung Res 1986;1O:267-83.

27 Rogers DF, Jeffery PK. Inhibition of cigarette smoke-induced airway secretory cell hyperplasia by indometha-cin, dexamethasone, prednisolone, or hydrocortisone inthe rat. Exp Lung Res 1986;1O:285-98.

28 Jeffrey PK. Anti-inflammatory drugs and experimentalbronchitis. Eur J Respir Dis 1986;146(Suppl):245-57.

29 Rogers DF, Jeffery PK. Indomethacin and flurbiprofenspeed recovery of rat bronchial epithelium after exposureto cigarette smoke. Exp Lung Res 1986;10:299-312.

30 Rogers DF, Godfrey RWA, Majumdar S, Jeffery PK. OralN-acetylcysteine speeds reversal of cigarette smoke-induced mucous cell hyperplasia in the rat. Exp Lung Res1988;14:19-35.

31 Balansky RB, D'Agostini F, Zanacchi P, DeFlora S. Protec-tion by N-acetylcysteine of the histopathological andcytogenetical damage produced by exposure of rats to

cigarette smoke. Cancer Lett 1992;64:123-31.32 Wright JL, Hobson JE, Wiggs B, Pare PD, Hogg JC.

Airway inflammation and peribronchiolar attachments inthe lungs of nonsmokers, current and ex-smokers. Lung1988;166:277-86.

33 Shields PA, Jeffery PK. The combined effects of vitamin A-deficiency and cigarette smoke of rat tracheal epithelium.BrJ Exp Pathol 1987;68:705-17.

34 Jeffery PK, Brain AP, Shields PA, Quinn BP, Betts T.Response of laryngeal and tracheo-bronchial surface lin-ing to inhaled cigarette smoke in normal and vitamin A-deficient rats: a scanning electron microscopic study.Scanning Microsc 1988;2:545-52.

35 Lasnitizki I, Bollag W. Prevention and reversal by a non-

polar arotinoid (Ro 15-0778) of 3,4-benzpyrene- andcigarette smoke condensate-induced hyperplasia andmetaplasia of rodent respiratory epithelia grown in vitro.Eur J Cancer Clin Oncol 1987;23:861-5.

36 Todisco T, Dottorini M, Rossi R, Baldoncini A, PulumboR. Normal reference values for regional pulmonary peri-pheral airspace epithelial permeability. Influence of pneu-monectomy and the smoking habit. Respiration1989;55:84-93.

37 Minty BD, Royston D, Jones JG, Hulands GH. The effectof nicotine on pulmonary epithelial permeability in man.

Chest 1984;86:72-4.38 Coates G, O'Brodovich H. Measurement of pulmonary

epithelial permeability with '9mTc-DTPA aerosol. SeminNucl Med 1986;16:275-84.

39 Holden WE, Maier JM, Malinow MR. Cigarette smokeextract increases albumin flux across pulmonary endothe-lium in vitro. J Appl Physiol 1989;66:443-9.

40 Lundberg JM, Lundblad L, Saria A, Anggard A. Inhibitionof cigarette smoke-induced oedema in the nasal mucosa bycapsaicin pretreatment and a substance P antagonist.Naunyn Schiedebergs Arch Pharmacol 1984;326:181-5.

41 Geppetti P, Bertrand C, Baker J, Yamawaki I, PiedmonteG, Nadel JA. Ruthenium red, but not capsazepine reducesplasma extravasation by cigarette smoke in rat airways. BrJ Pharmacol 1993;108:646-50.

42 Burns AR, Hosford SP, Dunn LA, Walker DC, Hogg JC.Respiratory epithelial permeability after cigarette smokeexposure in guinea pigs. J Appl Physiol 1989;66:2109-16.

43 Witten ML, Lemen RJ, Quan SF, Sobonya RE, RoseberryH, Stevenson JL, et al. Acute cigarette smoke exposureincreases alveolar permeability in rabbits. Am Rev RespirDis 1985;132:321-5.

44 Mordelet-Damrine M, Leguem-Stanislas G, Chinet TC,Barritault L, Chretien J, Huchon GJ. Effects of tobaccosmoke on respiratory epithelial clearance ofDTPA and on

lung histology in rats. Eur Respir Jr 1991;4:839-44.45 Boucher RC, Johson J, Inoue S, Hulbert W, Hogg JC. The

effect of cigarette smoke on permeability of guinea pigairways. Lab Invest 1980;43:94-100.

46 Hulbert WC, Forster BB, Mehta JG, Man SF, Molday RS,Walker BA, et al. Study of airway epithelial permeabilitywith dextran. J Electron Microsc Tech 1989;1 1:137-42.

47 Hulbert WC, Walker DC, Jackson A, Hogg JC. Airwaypermeability to horseradish peroxidase in guinea pigs: therepair phase after injury by cigarette smoke. Am RevRespir Dis 1981;123:320-6.

48 Rutten AA, Jongen WM, de Haan LH, Hendriksen EG,Koeman JH. Effect of retinol and cigarette-smoke conden-sate on dye-coupled intercellular communication betweenhamster epithelial cells. Carcinogenesis 1988;9:315-20.



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49 van der Zandt PT, de Feijter AW, Homan EC, Spaaij C, deHaan LH, van Aelst AC, et al. Effects of cigarette smokecondensate and 12-O-tetradecanoylphorbol-13-acetate ongap junction structure and function in cultured cells.Carcinogenesis 1990;11:883-8.

50 McKarns SC, Doolittle DJ. A quantitative approach toassessing intercellular communication: studies on cigarettesmoke condensates. Toxicol Appl Pharmacol 1991;1 11:58-68.

51 Rose MC. Mucins: structure, function, and role in pulmon-ary diseases. Am J Physiol 1992;263:L413-L429.

52 Wanner A. A review of the effects of cigarette smoke onairway mucosal function. Eur J Respir Dis1985;66(Suppl):49-53.

53 Lippman M, Schlesinger RB. Interspecies comparisons ofparticle deposition and mucociliary clearance. J ToxicolEnviron Health 1984;13:441-69.

54 Richardson MA. Upper airway complications of cigarettesmoking. J Allergy Clin Immunol 1988;91:1032-5.

55 Stanley PJ, Wilson R, Greenstone MA, MacWilliam L,Cole PJ. Effect of cigarette smoking on nasal mucociliaryclearance and ciliary beat frequency. Thorax 1986;41:519-23.

56 Lindberg S, Dolata J. NK1 receptors mediate the increasein mucociliary activity produced by tachykinins. Eur JPharmacol 1993;231:375-80.

57 Rubin BK, Ramirez 0, Zayas JG, Finegan B, King M.Respiratory mucus from asymptomatic smokers is betterhydrated and more easily cleared by mucociliary action.Am Rev Respir Dis 1992;145:545-7.

58 Sperber K, Gollub E, Goswani S, Kalb TH, Mayer L,Marom Z. In vivo detection of a novel macrophage-derived protein involved in the regulation of mucus-likeglycoprotein secretion. Am Rev Respir Dis 1992;146:1589-97.

59 Knowles MR, Buntin WH, Bromberg, Gatzy JT, BoucherRC. Measurements of transepithelial electric potentialdifferences in the trachea and bronchi ofhuman subjects invivo. Am Rev Respir Dis 1982;126:108-12.

60 Agnew JE, Pavia D, Clarke SW. Mucus clearance fromperipheral and central airways of asymptomatic cigarettesmokers. Bull Eur Physiopathol Respir 1986;22:263-7.

61 Agnew JE, Lopez-Vidriero MT, Parvia D, Clarke SW.Functional small airways defence in symptomless cigarettesmokers. Thorax 1986;41:524-30.

62 Welsh MJ. Cigarette smoke inhibition of ion transport incanine tracheal epithelium. J Clin Invest 1983;71:1614-23.

63 Desanctis GT, Kelly SM, Saettea MP, Shiner RJ, Stril JL,Hakim TS, et al. Hyporesponsiveness to aerosolized butnot infused methacholine in cigarette-smoking dogs. AmRev Respir Dis 1987;135:338-44.

64 Richardson PS, Peatfield AC. The control of airway mucussecretion. Eur J Respir Dis 1987;153(Suppl):43-51.

65 Kou HP, Rodhe JA, Barnes PJ, Rogers DF. Cigarettesmoke-induced airway goblet cell secretion: dose-depend-ent differential nerve secretion. Am J Physiol1992;263:L161-7.

66 Rogers DF, Turner NC, Marriott C, Jeffery PK. Cigarettesmoke-induced "chronic bronchitis": a study in situ oflaryngo-tracheal hypersecretion in the rat. Clin Sci1987;72:629-37.

67 Peatfield AC, Davies JR, Richardson PS. The effect oftobacco smoke upon airway secretion in the cat. Clin Sci1986;71:179-87.

68 Hummer B, Purnama I, Hahn HL. Stimulation of submu-cosal glands by nicotine applied locally to the airwaymucosa. Klin Wochenschr 1988;66(Suppl): 161-9.

69 Hobson J, Wright J, Churg A. Histochemical evidence ofgeneration of active oxygen species on the apical surface ofcigarette-smoke-exposed tracheal explants. Am J Pathol1991;139:573-80.

70 Sisson JH, Leise LK, Smith RA, Rennard SI, Cohen SM.Acrolein induces bronchial epithelial cell ciliostasis thatcan be blocked by N-acetylcysteine. Am Rev Respir Dis1991;143:A490.

71 Sisson JH, Tuma DJ, Rennard SI. Acetaldehyde-mediatedcilia dysfunction in bovine bronchial epithelial cells. Am JPhysiol 1991;260:L29-L36.

72 Maggi CA. Tachykinin receptors in the airways and lung:what should we block? Pharmacol Res 1990;22:527-32.

73 Morimoto H, Yamashita M, Matsuda A, Miyake H, FujiiT. Effects of FR 113680 and FK 224, novel tachykininreceptor antagonists on cigarette smoke-induced rat tra-cheal plasma extravasation. Eur J Pharmacol 1992;224:1-5.

74 Lundberg JM, Martling CR, Saria A, Folkers K, Rosell S.Cigarette smoke-induced airway oedema due to activationof capsaicin-sensitive vagal afferents and substance Prelease. Neuroscience 1983;10:1361-8.

75 Dusser DJ, Djokic TD, Borson DB, Nadel JA. Cigarettesmoke induces bronchoconstrictor hyperresponsiveness tosubstance P and inactivates airway neutral endopeptidasein the guinea pig. Possible role of free radicals. J ClinInvest 1989;84:900-6.

76 Von Essen SG, Rennard SI, O'Neill D, ErtlRF, RobbinsRA, Kayama S, et al. Bronchial epithelial cells releaseneutrophil chemotactic activity in response to tachykinins.Am JrPhysiol 1992;263:L226-L23 1.

77 DeRose V,Robbins RA, Spurzen JR, Snider RM, ThieleG, Rennard SI, etal. Substance P increased neutrophiladhesion to bronchial epithelial cells. Am Rev Respir Dis1992;145:A681.

78 Aguayo SM, Kane MA, King TE Jr, Schwarz MI, GrauerL, Miller YE. Increased levels of bombesin-like peptides

in the lower respiratory tract of asymptomatic cigarettesmokers. J Clin Invest 1989;84:1 105-13.

79 Meloni F, Bertoletti R, Corsico A, DiFazio P, CecchettinM, Gialdroni-Grassi G. Bombesin/gastrin releasing pep-tide levels of peripheral mononuclear cells, monocytes,and alveolar macrophages in chronic bronchitis. IntTissue React 1992;14:195-201.

80 Shipp MA, Tarr GE, Chen CY, Surtzer SN, Hersh LH,Stein H, et al. CD10/neutral endopeptidase 24.11 hydro-lyzes bombesin-like peptides and regulates the growth ofsmall cell carcinomas of the lung. Proc Natl Acad SciUSA 1991;88:100662-6.

81 Munakata M, Masaki Y, Sakuma I, Ukita H, Otsuka Y,Homma Y, et al. Pharmacologic differentiation of epithe-lium-derived relaxing factor from nitric oxide. J ApplPhysiol 1990;69:665-70.

82 Robbins RA, Hamel FG, Floreani AA, Gossman GL,Nelson KJ, Belenky S, et al. Bovine bronchial epithelialcells metabolize L-arginine to L-citrulline: possible role ofnitric oxide synthase. Life Sci 1993;52:709-16.

83 Jain B, Rubinstein I, Robbins RA, Leise KL, Sisson JH.Nitric oxide modulates ciliary activity in airway epithe-lium. Am Rev Respir Dis 1993;147:A937.

84 Jansen A, Drazen JM, Loscalzo J, Brown R, SugarbakerDA, Stamler JS. S-nitrosothiols: a new class of broncho-dilators. Am Rev Respir Dis 1991;143:A630.

85 Endo T, Uchida Y, Matsumoto H, Suzuki N, Nomura A,Hirata F, et al. Regulation of endothelin-I synthesis incultured guinea pig airway epithelial cells by variouscytokines. Biochem Biophys Res Commun 1992;186:1594-9.

86 Sparrows D, Glynn RJ, Cohen M, Weiss ST. The relation-ship of the peripheral leukocyte count and cigarette smok-ing to pulmonary function among adult men. Chest1984;86:383-6.

87 Hunninghake GW, Crystal RG. Cigarette smoking andlung destruction: accumulation of neutrophils in the lungsof cigarette smokers. Am Rev Respir Dis 1983;128:833-8.

88 Reynolds HV. Bronchoalveolar lavage. Am Rev Respir Dis1987;135:250-63.

89 Robbins RA, Shoji S, Linder J, Gossman GL. Bronchialepithelial cells release chemotactic activity for lympho-cytes. AmJ Physiol 1989;257:L109-15.

90 Anderson R, Theron AJ, Richards GA, Myer MS, vanRensburg AJ. Passive smoking by humans sensitizes cir-culating neutrophils. Am Rev Respir Dis 1991;144:570-4.

91 Totti N, McCusker KT, Campbell EJ, Griffin GL, SeniorRM. Nicotine is chemotactic for neutrophils and enhancesneutrophil responsiveness to chemotactic peptides. Sci-ence 1984;223:169-71

92 Nowak D, Ruta U, Paisecka G. Nicotine increases humanpolymorphonuclear leukocytes chemotactic response - apossible additional mechanism of lung injury in cigarettesmokers. Exp Pathol 1990;39:37-43.

93 Kew RR, Ghebrehiwet B, JanoffA. The role ofcomplementin cigarette smoke-induced chemotactic activity of lungfluids. Am Rev Respir Dis 1986;133:478-81.

94 Robbins RA, Gossman GL, Nelson KJ, Koyama S,Thompson AB, Rennard SI. Inactivation of chemotacticfactor inactivator by cigarette smoke. A potential mechan-ism of modulating neutrophil recruitment to the lung. AmRev Respir Dis 1990;142:763-8.

95 Gadek JE, Pacht ER. The protease-antiprotease imbalancewithin the lung: implications for the pathogenesis ofemphysema. Lung 1990;168:552-64.

96 Eling TE, Danilowicz RM, Henke DC, Sivarajah K, Yan-kaskas JR, Boucher RC. Arachidonic acid metabolism bycanine tracheal epithelial cells. Product formation andrelationship to chloride secretion. J Biol Chem1986;261:12841-9.

97 Churchill L, Chilton FH, Resau JH, Bascom R, HubbardWC, Proud D. Cyclooxygenase metabolism of endoge-nous arachidonic acid by cultured human tracheal epithe-lial cells. Am Rev Respir Dis 1989;140:449-59.

98 Wennmalm A, Benthin G, Granstrom EF, Persson L,Petersson AS, Winell S. Relation between tobacco use andurinary excretion of thromboxane A2 and prostacyclinmetabolites in young men. Circulation 1991;83:1698-704.

99 Wu Wang CY, Wang SL,Lim C, Milles M, Slomiany A,Slomiany BL. Cigarette smoking reduces human salivaryeicosanoids. Prostaglandins Leukot Essent Fatty Acids1992;47:101-4.

100 Nagase T, Fukuchi Y, Shimizu T, Yamaoka M, Matsuse T,Hirose T, et al. The influence of cigarette smoke onmetabolism of ;cosanoids in rat lung in terms of variationof 15-hydroxeicosatetraenoic acid and 11 -dehydrothrom-boxane B2. Nippon Kyobu Shikkan Gakkai Zasshi1989;27: 193-7.

101 Leikauf GD, Leming LM, O'Donnell JR, Doupnik CA.Bronchial responsiveness and inflammation in guinea pigsexposed to acrolein. 7Appl Physiol 1989;66:171-8.

102 Jeremy JY, Mikhailidis DP, Dandona P. Muscarinic stimu-lation of prostanoid synthesis by isolated rat trachea:calcium dependency and effect of cortisol and cigarettesmoke. Eur J Pharmacol 1989;160:107-15.

103 Thomas PS, Schreck RE, Lazarus SC. Tobacco smokereleases preformed mediators from canine mast cells andmodulates prostaglandin production. Am J Physiol1992;263:L67-72.

104 Cox G, Gauldie J, Jordana M. Bronchial epithelial cell-derived cytokines (G-CSF and GM-CSF) promote thesurvival of peripheral blood neutrophils in vitro. Am JRespir Cell Mol Biol 1992;7:507-13.

105 Becker S,Koren HS, Henke DC. Interleukin-8 expression

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Dye, Adler

in normal nasal epithelium and its modulation by infectionwith respiratory syncytial virus and cytokines tumor nec-rosis factor, interleukin-1, and interleukin-6. Am J7 RespirCell Mol Biol 1993;8:20-7.

106 Ohtoshi T, Vancheri C, Cox G, Gauldie J, Dolovich J,Denburg JA, et al. Monocyte-macrophage differentiationinduced by human upper airway epithelial cells. AmRespir Cell Mol Biol 1991;4:255-63.

107 Francus T, Romano PM, Manzo G, Fonacier L, Arango N,Szabo P. IL-1, IL-6, and PDGF mRNA expression inalveolar cells following stimulation with a tobacco-derivedantigen. Cell Immunol 1992;145:156-74.

108 Dubar V, Gosset P, Aerts C, Voisin C, Wallaert B, TonnelAB. In vitro acute effects of tobacco smoke on tumornecrosis factor alpha and interleukin-6 production byalveolar macrophages. Exp Lung Res 1993;19:345-59.

109 Soliman DM, Twigg HL III. Cigarette smoking decreasesbioactive interleukin-6 secretion by alveolar macrophages.Am Physiol 1992;263:L471-8.

110 Hance AJ, Basset G, Saumon G, Danel C, Valeyre D,Battesti JP, et al. Smoking and interstitial lung disease: theeffect of cigarette smoking on the incidence of pulmonaryhistiocytosis X and sarcoidosis. Ann NY Acad Sci1986;465:643-56.

111 Tosi MF, Stark JM, Smith CW, Hamedani A, GruenertDC, Infeld MD. Induction of ICAM-1 expression onhuman airway epithelial cells by inflammatory cytokines:effects on neutrophil-epithelial cell adhesion. Am RespirCell Mol Biol 1992;7:214021.

112 MacNee W, Wiggs B, Belzberg AS, Hogg JC. The effect ofcigarette smoking on neutrophil kinetics in human lungs.N Engl Med 1989;321:924-8.

113 Bosken CH, Doerschuk CM, English D, Hogg JC. Neutro-phil kinetics during active cigarette smoking in rabbits.Appl Physiol 1991;71:630-7.

114 Lehr HA, Kress E, Menger MD. Involvement of 5-lipoxy-genase products in cigarette smoke-induced leukocyte/endothelium interaction in hamsters. Int Microcirc ClinExp 1993;12:61-73.

115 Drost EM, Selby C, Lannan S, Lowe GDO, MacNee W.Changes in neutrophil deformability following in vitrosmoke exposure: mechanism and protection. Am RespirCell Mol Biol 1992;6:287-95.

116 Klut ME, Doerschuk CM, Van Eeden SF, Bums AR, HoggJC. Activation of neutrophils within pulmonary microves-sels of rabbits exposed to cigarette smoke. Am RespirCell Mol Biol 1993;9:82-9.

117 Baluk P, Hatzidakis A, Nadel JA, McDonald DM. Chronicexposure to cigarette smoke potentiates capsaicin-inducedneutrophil adhesion in rat trachea. Am Rev Respir Dis1992;145:A188.

118 Robbins RA, Koyama S, Spurzem JR, Rickard KA, NelsonKJ, Gossman GL, et al. Modulation of neutrophil andmononuclear cell adherence to bronchial epithelial cells.Am Respir Cell Mol Biol 1992;7:19-29.

119 Selby C, Drost E, Brown D, Howie S, MacNee W. Inhibi-tion of neutrophil adherence and movement by acutecigarette smoke exposure. Exp Lung Res 1992;18:813-27.

120 Holt PG. Immune and inflammatory function in cigarettesmokers. Thorax 1987;42:241-9.

121 Savage SM, Donaldson LA, Cherian S, Chilukuri R, WhiteVA, Sopori ML. Effects of cigarette smoke on the immuneresponse. II. Chronic exposure to cigarette smoke inhibitssurface immunoglobulin-mediated responses in B cells.Toxicol Appl Pharmacol 1991;111:523-9.

122 Spurzem JR, Sacco 0, Rossi GA, Beckmann JD, RennardSI. Regulation of major histocompatibility complex classII gene expression on bovine bronchial epithelial cells.Lab Clin Med 1992;120:94-102.

123 McDevitt CA, Beck GJ, Ciunga MJ, O'Brien J. Cigarettesmoke degrades hyaluronic acid. Lung 1989;167:237-45.

124 Pladsen P, Beckman J, Rennard S, Romberger D. Cigarettesmoke extract modulates bronchial epithelial cell fibronec-tin release. Am Rev Respir Dis 1992;145:A826.

125 Cantral DE, Veys T, Sission JH, Rennard SI, Spurzem JR.Exposure of bronchial epithelial cells to cigarette smokeextract impairs migration. Am Rev Respir Dis1993;147:A46.

126 Barrett JC, Lamb PW, Wiseman RW. Multiple mechan-isms for the carcinogenic effects of asbestos and othermineral fibers. Environ Health Perspect 1989;81:81-9.

127 Kamp DW, Graceffa P, Pryor WA, Weitzman SA. The roleof free radicals in asbestos-induced disease. Free RadicBiol Med 1992;12:293-315.

128 McFadden D, Wright J, Wiggs B, Churg A. Cigarettesmoke increases the penetration of asbestos fibers intoairway walls. Am Pathol 1986;123:95-9.

129 Churg A, Wright JL, Hobson J, Stevens B. Effects ofcigarette smoke on the clearance of short asbestos fibresfrom the lung and a comparison with the clearance of longasbestos fibres. Int Exp Pathol 1992;73:287-97.

130 Churg A, Hobson J, Wright J. Effects of cigarette smokedose and time after smoke exposure on uptake of asbestosfibers by rat tracheal epithelial cells. Am Respir Cell MolBiol 1990;3:265-9.

131 Churg A, Hobson J, Berean K, Wright J. Scavengers ofactive oxygen species prevent cigarette smoke-inducedasbestos fiber penetration in rat tracheal explants. AmPathol 1989;135:599-603.

132 Keeling B, Hobson J, Churg A. Effects of cigarette smokeon epithelial uptake of non-asbestos mineral particles intracheal organ culture. Am Respir Cell Mol Biol1993;9:335-40.

133 Takahashi K. Patho-physiological changes in the lung par-enchyma caused by exposure of tobacco smoke in thehamster. Nippon Kyobu Shikkan Gakkai Zasshi (7apanese

Thoracic Dis) 1991;29:190-6.134 Nilsson K, Henriksson R, Cai YQ, Hellstroms S, Hornq-

vist-Bylunds S, Bjermer L. Effects of tobacco smoke onradiation-induced pneumonitis in rats. Int Radiat Biol1992;62:719-27.

135 Nishikawa M, Ikeda H, Nishiyama H, Yamakawa H,Suzuki S, Okubo T. Combined effects of ozone andcigarette smoke on airway responsiveness and vascularpermeability in guinea pigs. Lung 1992;170:311-22.

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