Letter to the Editor

Chlamydia pneumonia and Stroke

Authors: Zaki Noah Hasan, FICMS

Abstract

To the Editor:


The association between stroke and Chlamydia pneumonia infections is still unclear. Proposed mechanisms behind the risk of stroke in patients with acute and chronic infections are multiple and variable and include vasculitis, increased platelet adhesiveness, increased leukocyte recruitment, cytokines production and a high association with rheumatologic diseases. Other mechanisms involve matrix metalloproteinase-9 expression which is associated with the presence of Chlamydia pneumonia in human coronary atherosclerosis.1 Matrix metalloproteinases are prevalent in the arterial wall throughout the arterial system and are associated with local plaque destabilization.2Chronic Chlamydia pneumoniae infection may promote coronary artery disease in humans through enhancing secretion of interleukin-4,3which augments cholesterol esterification in macrophages leading to profound increment of the atherogenic process.4 Also Chlamydia pneumonia induces macrophage-derived foam cell formation by up-regulating cholesterol acyltransferase (acyl-coenzyme A and cholesterol acyltransferase)5; those enzymes regulate cholesterol storage as cholesterol ester in the vascular walls and many other organs.6 Also chronic C. pneumoniae infection has been associated with increased triglyceride and decreased high-density lipoproteins.7

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References

1. Arno G, Kaski JC, Smith DA, et al. Matrix metalloproteinase-9 expression is associated with the presence of Chlamydia pneumoniae in human coronary atherosclerotic plaques. Heart 2005;91:521-525.
 
2. Peeter W, Moll F, Vink A, et al. Collagenase matrix metalloproteinase-8 expressed in atherosclerotic carotid plaques is associated with systemic cardiovascular outcome. Eur Heart J 2011 February 2 [Epub ahead of print].
 
3. Clancy R, Ren Z, Pang G, et al. Chronic Chlamydia pneumoniae infection may promote coronary artery disease in humans through enhancing secretion of interleukin-4. Clin Exp Immunol 2006;146:197-202.
 
4. Cornicelli JA, Butteiger D, Rateri DL, et al. Interleukin-4 augments acetylated LDL-induced cholesterol esterification in macrophages. J Lipid Res 2000;41:376-383.
 
5. He P, Mei C, Cheng B, et al. Chlamydia pneumoniae induces macrophage-derived foam cell formation by up-regulating acyl-coenzyme A: cholesterol acyltransferase 1 [published online ahead of print November 18, 2008]. Microbes Infect 2009;11:157-163.
 
6. Hienonon TN. Acyl coenzyme A: cholesterol acyltransferase inhibition: potential atherosclerosis therapy or springboard for other discoveries? Expert Opin Investig Drugs 2002;11:1519-1527.
 
7. Bandaru VSB, Demudu B, Vineeta S, et al. Role of Chlamydia pneumoniae in pediatric acute ischemic stroke: a hospital based study. J Pediatr Neurol 2010;8:367-369.
 
8. Elkind MS, Ramakrishnan P, Moon YP, et al. Infectious burden and risk of stroke: the Northern Manhattan study. Arch Neurol 2010;67:33-38.
 
9. Hirono S, Dibrov E, Hurtado C, et al. Chlamydia pneumoniae stimulates proliferation of vascular smooth muscle cells through induction of endogenous heat shock protein 60. Circ Res 2003;93:710-716.