Exposure to agriculture dust particles during allergen sensitization exacerbates allergic

airway inflammation

Alex Castañeda, M.S.Graduate Group in Immunology

University of California Davis

Dr. Kent PinkertonDirector, Center for Health & the EnvironmentDepartment of Pediatrics, School of Medicine

Professor of Anatomy, Physiology and Cell BiologyUC Davis School of Veterinary Medicine

AsthmaAllergen

Environmental/OccupationalFactors

Genetic FactorsKim et al. 2010. The many pathways to asthma. Nature Immunology 11: 577-584

Ambient Particles

Ovalbumin

Symptoms: Airway inflammation, bronchial constriction, coughing, wheezing, and shortness of breath

Prevalence: 235 million people worldwide (11 million in the US)

In California (San Joaquin Valley) 25% of all children are diagnosed with allergic asthma

Allergic Asthma

Studies have shown a correlation between asthma and high particulate matter exposure-Particular matter exacerbate asthma-The use of source specific ambient particles has not been studied

Particulate Matter:Vehicle emissions (gasoline)Agricultural DustsDiesel exhaust gasesMineral dustsHydrocarbons

Particles Size:Coarse particlesFine ParticlesUltrafine particles (0.1µm in diameter)

Location:Fresno California (Leading agriculture-producing county in the nation)Particles collected during summer nights (2010)

Particle Pollution

Agricultural DustGeneration

Field preparation for crops, fertilization, crop harvest (ex- almonds)

CompositionInorganic (Mineral Dusts)

Silcates (aluminum silicates), quartz, transition metals

Organic (Carbonates)

Toxicity of Inorganic Agricultural DustsCellular toxicityGenerate free radicalsOxidative cellular stressActivation of the immune system towards an inflammatory state -Fibrogenesis

Hypothesis

Exposure to agricultural dust particles during sensitization with an allergen (house dust mites or ovalbumin) will exacerbate airway inflammation in BALB/c mice

MethodsMurine Model- BALB/c mice

Treatments Allergen- OVA, Purified OVA or

Purified House Dust Mites (HDM)Agricultural Dust- Ultrafine Particles (Fresno)

Sensitization (days 1, 3, & 5)OVA & pOVA- 10ug intranasalHDM- 25ug intranasal

Challenge (days 12, 13, & 14)OVA & pOVA- 10ug aerosolized HDM- 10 ug OVA

0 5 10 15

Allergen Sensitization+

Allergen Challenge

Necropsy

Ambient Particles

Groups 1 -Control (No Allergen + Filtered Air)2- OVA + Filtered Air3- OVA + Particulate Matter4- pOVA + Filtered Air5- pOVA + Particulate Matter 6- pHDM + Filtered Air7- pHDM + Particulate Matter

Tissue CollectionBlood Plasma (IgE,IgG1)BALFLung (Homogenize & Fixed)

BALF Cellular ProfliesMacrophages

Neutrophils

Total Cells

Eosinophils

Results- Tissue HistologyControl Allergen and particulate matter

Mucosubstance

Alcian Blue Periodic Acid Schiff’s Stain

Results- Tissue Histology

P MD

µm3

µm2Airway Inflammation:

Volume of Intraepithelial Mucosubstances

Area of Basal Lamina( )

Results- Tissue Histology

P MD

Results- Total Protein

Results- Antibody Production

Results- IL-17-A Production

Barnes et al. 2008. Immunology of asthma and COPD.Nature Reviews Immunology 8, 183-192

Results- IL-17-E Production

SummaryAirway inflammation was exacerbated when

particulate matter was introduced during allergen sensitization (HDM only, not OVA)-Significantly elevated levels of total cells, macrophages, and neutrophils

Based on muco-substance production HDMA causes significantly more airway inflammation over Ova

IL-17A production was elevated in the HDMA model, correlating with increased neutrophils, however there is no correlation to particles

Future Work

Investigate the mechanisms through which agricultural dust enhances airway inflammation-How particles activate the immune system?

Investigate neutrophil infiltration-Do particles increase neutrophilic inflammation?

AcknowledgementsPinkerton Laboratory UC Davis Western Center for Agricultural Health and Safety

Kent Pinkerton, Ph.D. Marc Schenker, M.D. Chris Carosino Sandra FreelandDale Uyeminami All other membersJanice PeakeKatherine Johnson Graduate Group in ImmunologyImelda EspirituAlexa PhamEsther ShinJocelyn ClaudeAll other members