Is Chlamydia pneumoniae infection a risk factor for age related macular degeneration?

Abstract

The association between a pathogen and AMD is worth further investigation because a new approach might treat this incurable vision threatening disease Age related macular degeneration (AMD) is a leading cause of decreased central vision in older people throughout the world. The pathogenesis of AMD is very complex and has still not been determined. In addition to some genetic and environmental factors, several kinds of risk factors have been proposed; sunlight exposure,1 smoking,2 and low levels of nutritional components such as antioxidants.3 Hypertension,4 hyperlipidaemia,4 and atherosclerosis,5,6 which may lead to cardiovascular diseases, are also considered to be risk factors. Chronic inflammatory events have recently been identified as plausible causes of atherosclerosis. In particular, much interest has been focused on infections by Chlamydia pneumoniae , which was previously known as the TWAR strain. This strain is one of the chlamydial species that has been recognised as a causal mediator of respiratory infections such as bronchitis, pneumonia, and upper respiratory tract infections.7 Chlamydia can multiply in various host cells including macrophages and endothelial cells.8 C pneumoniae is like a parasite and consumes energy that is needed by the host cells and, in the end, destroys them and then infects nearby cells. Thus, the pathogens tend to cause a chronic infection. The first study showing a positive interaction between systemic vascular disease and infection with C pneumoniae was made by Saikku et al in 1988.9 They reported increased immunoglobulin G (IgG) and IgA antibody titres against C pneumoniae in male patients with myocardial infarction or chronic coronary heart disease. Since then, attention has been focused on its association with atherosclerotic diseases.10 A strong piece of evidence indicating a close interaction between C pneumoniae …