Editorial Slides VP Watch - May 15, 2002 - Volume 2, Issue 19

PTX3 or CRP?PTX3; A New Kid on the Atherosclerosis Block!

Osmand et al. in 1977 found that CRP is composed of five subunits arranged in cyclic symmetry. This structure was similar to that reported for both C1t (complement component C1) and amyloid P. They

proposed the term Pentraxin to describe these homologous proteins as a a subclass of acute phase proteins. 1

Pentraxin-3 (PTX3) is a newly discovered marker of the acute phase response from Pentraxin family.

Pentraxin; Cyclic Pentametric Structure

In 1993, Mantovani, Breviario, and others cloned PTX-3 gene form IL-1β treated human umbilical vein endothelial cells (HUVEC). PTX3 gene has been localized on human chromosome 3. 2,3

The PTX3 mRNA is induced in endothelial, hepatic, and fibroblastic cells by IL-1β and TNF-α but not by IL-6 and interferon-γ.3

Alles, Mantovani, and colleagues found that PTX3, unlike the classical Pentraxins CRP and serum amyloid P, is expressed and released by cells of monocyte-macrophage lineage exposed to inflammatory signals (extrahepatic expression). 4

PTX3 Unlike CRP Is Extrahepatic

In vivo, the PTX3 gene is most prominently induced in mouse heart and skeletal muscle. 8

In other study Luchetti et al. by using immunoenzymatic assay, detected increased levels of PTX3 in synovial fluids from patients with rheumatoid arthritis.5

Other long pentraxins, such as murine or rat neuronal pentraxin-1 and human neuronal pentraxin 2, are expressed in the central nervous system.

Intracerebroventricular, but not intravenous, injection of LPS induces high levels of PTX3 mRNA in the mouse brain. 6

Pentraxin In Other Diseases

Expression of PTX3 binding sites occurs late in apoptotic process. PTX3 binding inhibits recognition of apoptotic cells by dendritic cells. Human dendritic cells fail to internalize dying cells in the presence of PTX3, while they take up normally soluble or inert particulate substrates. 8

Pentraxin and Apoptosis

• Peri, Latini, and colleagues showed that PTX3 (long Pentraxin) peaked rapidly in patients with MI symptoms after admission to the hospital and preceded the increase of CRP (short Pentraxin).

• PTX3 which is present in normal and hypertrophied human cardiomyocytes, is increased in the blood of patients with acute MI, and disappears from necrotic myocytes. PTX3 increases in the blood of patients with acute MI because it is released from dying or necrotic cells. 7

PTX3 in MI

As reported in VP Watch of this week, Hansson et al. recently showed that

immunohistochemical staining of advanced atherosclerotic plaques revealed strong

expression of PTX3. In contrast, no PTX3 expression was observed in nonatherosclerotic internal mammary arteries.

They found that staining serial sections with cell type– and PTX3-specific antibodies, we observed that PTX3 was produced principally by macrophages and endothelial cells. Infrequent expression by smooth muscle cells was also observed. 9

Also Napoleone, Lorenzet, and colleagues found that PTX3 increases tissue factor (TF) expression in HUVECs exposed to other inflammatory mediators like LPS, IL-1ß, and TNF-α. 10

Increasing TF mRNA determined by PTX3 originated from an enhanced nuclear binding activity of transacting factor.

TF Activity in HUVECs Exposed to Different Concentrations of PTX3

0

50

100

150

200

250

0 1 5 10

LPSIL-1betaTNF-alpha

TF activity in HUVECs exposed to different concentrations of PTX3. HUVECs were incubated with LPS (1 µg/mL), IL-1ß (10 ng/mL), or TNF- (10 ng/mL) in the presence of different amounts of PTX3. Treatment conditions were as outlined in the legend of Figure 1. The data represent the mean±SEM of 3 duplicate experiments. For each agonist, *P<0.05 vs sample without PTX3.

Emanuela Napoleone, Angelomaria Di Santo, Antonio Bastone, Giuseppe Peri, Alberto Mantovani, Giovanni de Gaetano, Maria Benedetta Donati, and Roberto Lorenzet Long Pentraxin PTX3 Upregulates Tissue Factor Expression in Human Endothelial Cells: A Novel Link

Between Vascular Inflammation and Clotting Activation ;Arterioscler Thromb Vasc Biol 2002 22: 782 - 787

TF activity, U/well

PTX3,μg/ml

Effect of PTX3 on IκBα Degradation in Stimulated HUVECs

0102030405060708090

100

PTX3 IL-1beta TNF-alpha+PTX3

PTX3 LPS LPS+PTX3 IL-1beta IL-1beta+PTX3 TNF-alpha TNF-alpha+PTX3

Effect of PTX3 on I B degradation in stimulated HUVECs. HUVECs were incubated with LPS (1 µg/mL), IL-1ß (10 ng/mL), or TNF- (10 ng/mL) with or without PTX3 (5 µg/mL) for 5 minutes at 37°C. Proteins were extracted, and I B was determined by Western blotting. The blots were scanned and quantified in AUs with NIH Image software, version 1.62. Data are the mean±SEM of 3 separate experiments. The unit calculated for the band obtained from the control cells was assigned a 100% value. In the inset, a representative Western blot is shown.

Emanuela Napoleone, Angelomaria Di Santo, Antonio Bastone, Giuseppe Peri, Alberto Mantovani, Giovanni de Gaetano, Maria Benedetta Donati, and Roberto Lorenzet Long Pentraxin PTX3 Upregulates Tissue Factor Expression in Human Endothelial Cells: A Novel Link Between Vascular

Inflammation and Clotting Activation ;Arterioscler Thromb Vasc Biol 2002 22: 782 - 787

Conclusion

These observations and the presence of PTX3 during the early phases of inflammation offer the biological plausibility for a role of PTX3 in atherosclerosis (plaque inflammation, apoptosis, and thrombosis).

Because of its extrahepatic source, PTX3 may be superior to CRP.

Questions:

• What are the major sources of PTX3 in the body?

• Knowing hepatic production of CRP makes it a nonspecific marker, can PTX3 (solely extrahepatic) offer a major advantage over CRP for detection of plaque inflammation?

Questions:• Is high PTX3 blood level in patients with

MI released by myocardial injury or atherosclerotic plaques (cause or effect)?

• Increased tissue factor activity and reduced uptake of apoptotic bodies caused by PTX3 makes it a culprit for plaque vulnerability, does this mean that PTX3 can be a target for therapy and plaque stabilization?

1) Osmand AP, Friedenson B, Gewurz H, Painter RH, Hofmann T, Shelton E.; Characterization of C-reactive protein and the complement subcomponent C1t as homologous proteins displaying cyclic pentameric symmetry (pentraxins). Proc Natl Acad Sci U S A. 1977 Feb;74(2):739-43.

2) Introna M, Breviario F, d'Aniello EM, Golay J, Dejana E, Mantovani A. ; IL-1 inducible genes in human umbilical vein endothelial cells.; Eur Heart J. 1993 Dec;14 Suppl K:78-81.

3) Breviario F, d'Aniello EM, Golay J, Peri G, Bottazzi B, Bairoch A, Saccone S, Marzella R, Predazzi V, Rocchi M, et al. ; Interleukin-1-inducible genes in endothelial cells. Cloning of a new gene related to C-reactive protein and serum amyloid P component. ; J Biol Chem. 1992 Nov 5;267(31):22190-7.

4) VV Alles, B Bottazzi, G Peri, J Golay, M Introna, and A Mantovani; Inducible expression of PTX3, a new member of the pentraxin family, in human mononuclear phagocytes Blood 84: 3483-3493

5) Luchetti MM, Piccinini G, Mantovani A, Peri G, Matteucci C, Pomponio G, Fratini M, Fraticelli P, Sambo P, Di Loreto C, Doni A, Introna M, Gabrielli A.; Expression and production of the long pentraxin PTX3 in rheumatoid arthritis (RA).Clin Exp Immunol. 2000 Jan;119(1):196-202.

6) Polentarutti N, Bottazzi B, Di Santo E, Blasi E, Agnello D, Ghezzi P, Introna M, Bartfai T, Richards G, Mantovani A.; Inducible expression of the long pentraxin PTX3 in the central nervous system. J Neuroimmunol. 2000 Jul 1;106(1-2):87-94.

7) Peri G, Introna M, Corradi D, Iacuitti G, Signorini S, Avanzini F, Pizzetti F, Maggioni AP, Moccetti T, Metra M, Cas LD, Ghezzi P, Sipe JD, Re G, Olivetti G, Mantovani A, Latini R.; PTX3, A prototypical long pentraxin, is an early indicator of acute myocardial infarction in humans.; Circulation. 2000 Aug 8;102(6):636-41.

8) Vidal Alles V, Bottazzi B, Peri G, et al. Inducible expression of PTX3, a new member of the pentraxin family, in human mononuclear phagocytes. Blood. 1994;84:3483–3493.

9) Michael S. Rolph, Sabine Zimmer, Barbara Bottazzi, Cecilia Garlanda, Alberto Mantovani, and Göran K. Hansson ; Production of the Long Pentraxin PTX3 in Advanced Atherosclerotic Plaques ; Arterioscler Thromb Vasc Biol 2002 22: e10 - e14

10) Emanuela Napoleone, Angelomaria Di Santo, Antonio Bastone, Giuseppe Peri, Alberto Mantovani, Giovanni de Gaetano, Maria Benedetta Donati, and Roberto Lorenzet Long Pentraxin PTX3 Upregulates Tissue Factor Expression in Human Endothelial Cells: A Novel Link Between Vascular Inflammation and Clotting Activation Arterioscler Thromb Vasc Biol 2002 22: 782 - 787

References