Virus-infected monocytes can initiate coagulation and promote inflammation. An in vitro study found that monocytes infected with cytomegalovirus, influenza A virus, or Chlamydia pneumoniae expressed tissue factor and reduced clotting time, indicating initiation of coagulation. The viruses also stimulated monocytes to produce inflammatory cytokines like IL-6 and IL-8. While all three viruses infected monocytes, influenza A most strongly induced cytokine production. This suggests virus-infected monocytes may contribute to both acute coronary events by promoting plaque instability and the chronic atherosclerosis process through sustained inflammation and coagulation.
Artifacts in Nuclear Medicine with Identifying and resolving artifacts.
190 virus infected monocyes
1. Procoagulant And Inflammatory Response of
Virus-Infected Monocyes
Provided by:
Enrique Gurfinkel , MD, PhD
Fundación Favaloro, Capital Federal, Buenos Aires, Argentina
Editorial Slides
VP Watch – November 13, 2002 - Volume 2, Issue 45
2. Introduction
• Atherosclerosis is thought to be an inflammatory
disease, but its origin still remains unanswered.
• Chronic low-grade inflammation and combination
of classical risk factors, plus novel risk factors
such as the infectious burden seem to contribute
to promote atherosclerosis.
3. Introduction
• Monocytes play a prominent role in
inflammation, coagulation and the ability to
produce tissue factor and cytokines.
• All of these factors, particularly the production of
cytokines may contribute to acute coronary
syndromes by eliciting plaque instability.
4. Background
• During viral infections monocytes predominantly
produce inflammatory cytokines.
• In addition, continuing viral infection may sustain
excess tissue factor production and exhaust the
inhibitory effects of tissue factor pathway
inhibitor.
5. As highlighted in VP Watch of this week,
• Bouwman and co-workers tried to establish
whether virus-infected monocytes initiate
coagulation.
And
• To detect if the production of cytokines by
monocytes may contribute to the chronic
process of atherosclerosis in an in-vitro model.
6. Methods
• Isolation of monocytes:
monocytes obtained from fresh
blood of healthy volunteers.
7. Methods
• Preparation of virus stocks: Human embryonic
lung, human epidermoid larynx carcinoma, and
LLC-MK2 cells were cultured in Eagles´s
minimum essential medium with Earle´s salts.
• A clinical isolete of CMV was propagated in HEL
cells
• Chlamydia pneumoniae strain AR 39 was
propagated in HEP-2 cells
• Influenza A HIN1 86 Singapore was propagated
in LLC-MK2 cells
8. Methods
• Coagulation assay: Normal pooled plasma
was prepared from the blood of nine
healthy donors.
• Cytokine assays: IL 6, 8, and 10 were
measured in the supernatants of virus-
infected monocytes.
9. It appeared that all strains could infect monocytes, but in all cases the infection
was below 5% when undiluted virus stocks were used.
Fluorescence microscopy images of virus-
infected monocytes. Magnification 200x after
overnight incubation; Red background: uninfected
monocytes. Green areas: virus-infected monocytes
stained with FITC-labeled anti-virus antibodies.
(a) CMV, specific staining of CMV in the nuclei
of the infected cells. (b) Influenza A, smooth
staining pattern of influenza A in monocytes. (c)
Cp, more dense staining pattern of Cp in the
cytoplasm of monocytes.
10. 80% of the monocytes were covered with
activated CD41+ CD42+
Ficoll + VPT+ VPT+
Depletion Depletion Positive Selection
CD41+ CD42+ 46% 78% 3%
11. CMV and Cp, like influenza, reduced the clotting time.
The inititation of coagulation by virus-infected monocyes
was a result of the expression of TF.
Clottingtime(seconds)
Uninfected monocytes Infected monocytes
140+-22.1 s
333+-22.1s
12. Infection with CMV and Cp induced the production of
modest levels of IL6 and IL8, whereas infection with influenza A
strongly stimulated the production of IL6 and 8.
IL-6IL-8(pgml)
CMV & Cp
IL 6
1000
IL-8
H1N1
2000
13. Discussion
• The results of the present study
indicate that only small quantities of an
infectious virus are needed to stimulate
monocytes to exert considerable
immunological effects.
14. Conclussions
• The procoagulant activity of virus-
infected monocytes is TF-dependent.
• Influenza infection induced a
pronounced expression of IL-6 and IL-
8, which could be associated with
plaque rupture.
15. Questions
• Is there any differences between the
bacterial and viral infectious burden in
promoting procoagulant activity?
• Is it plausible to think that this could
explain a systemic pro-thrombotic
process after infection?
16. 1. Buja LM. Does atherosclerosis have an infectious etiology? Circulation 1996;94:872.
2. Burch GE, Tsui CY, Harb JM. Pathologic changes of aorta and coronary arteries of mice
infected with Coxsackie B virus. Proc Soc Exp Biol Medl 1971;137:657–61.
3. Mosorin et al. Detection of Chlamydia pneumoniae-Reactive T lymphocytes in human
atherosclerotic plaques of the carotid artery. Arterioscl Thromb Vasc Biol 2000;20:1061–7.
4. Blankenberg S, Rupprecht HJ, Bickel C, Espinola-Klein C, Rippin G et al.
Cytomegalovirus infection with interleukine 6 response predicts cardiac mortality
in patients with coronary artery disease. Circulation 2001;103 (24):2915–21.
5. Visseren FLJ, Bouwman JJM, Bouter KP, Diepersloot RJA, de Groot Ph, Erkelens DW. Procoagulant
activity of endothelial cells after infection with respiratory viruses. Thromb Haemost 2000;84 (2):319–24.
6. Frostegard J, Ulfgren A, Nyberg P, Hedin U, Swedenborg J et al. Cytokine expression in advanced
human atherosclerotic plaques: dominance of pro-inflammatory (Th1) and macrophage stimulating
cytokines. Atherosclerosis 1999;145:33–43.
7. Neumann FJ, Ott I, Marx N, Luther T, Kenngott S et al.
Effect of human recombinant Interleukin-6 and Interleukin-8 on Monocyte Procoagulant activity.
Arteriosclerosis Thromb Vasc Biol 1997;17:3399–405.
8. Bouwman J. J. M. et al,. Eur J Clin Invest 2002; 32 (10): 759-766
References