Bacterial Infection Linked to AMD

by Dan Roberts
(Updated November 13, 2005)
According to a report in the April 2003 issue of the Archives of Ophthalmology (2003;121:478-482.), the bacterium Chlamydia pneumoniae may lead to a higher risk of age-related macular degeneration (AMD). The researchers found that people with AMD tend to carry higher levels of antibodies targeted against C. pneumoniae, which is an indication of past infection.
C. pneumoniae infection is common in the respiratory system, but it is also suspected of promoting certain chronic diseases related to blood vessel inflammation. This includes heart disease and atherosclerosis. Such chronic inflammation may also contribute to AMD, according to researchers led by by Dr. Murat V. Kalayoglu of the Massachusetts Eye and Ear Infirmary in Boston. This conclusion was drawn after studying blood samples from 43 patients, 25 of whom had AMD and showed higher levels of anti-C. pneumoniae antibodies than the patients without AMD.
Further evidence was presented in a study published in the November issue of the journal Graefe’s Archive for Clinical and Experimental Ophthalmology (Massachusetts Eye and Ear Infirmary, Dr. Murat Kalayoglu, lead author). That study found C. pneumoniae in the diseased eye tissue of five of nine people with wet AMD but not in the eyes of 20 people without AMD. The researchers found that “C. pneumoniae is capable of modifying the function of important cell types involved in regulating normal eye function,” and that “C. pneumoniae infection led to increased production of vascular endothelial growth factor (VEGF), the key protein involved in wet AMD.” This, they hypothesized, could partially explain the increased VEGF levels in many AMD patients, and that C. pneumoniae may be acting as an accelerant of inflammation in AMD patients who have variations in their complement factor H (CFH) gene.
The next step is to investigate whether bacteria-fighting antibiotics could help treat artery disease, and potentially, AMD by protecting the eye tissues from inflammation caused by the bacteria.