Higher Levels of Systemic Inflammatory Markers Associated with Progression of AMD
Loss of Visual Function
Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment and blindness among persons aged 60 and older. With the elderly population steadily growing, the burden related to this loss of visual function will increase. Limited treatment options exist and prevention remains the best approach for addressing this public health concern.
AMD and cardiovascular disease share common risk factors. Inflammatory biomarkers, including C-reactive protein (CRP) and interleukin 6 (IL-6), have been associated with cardiovascular disease. Researchers led by Johanna M. Seddon, M.D., at the Massachusetts Eye and Ear Infirmary, Harvard Medical School and Harvard School of Public Health, conducted a prospective longitudinal study to examine several biomarkers for cardiovascular disease, including CRP and IL-6, to measure the relationship between these biomarkers and incidence rates of progression of AMD. They found that higher levels of the systemic inflammatory markers CRP and IL-6 are independently associated with the progression of AMD.
"To our knowledge, this is the first prospective study to report a positive association between the systemic inflammatory markers CRP and IL-6 and the rate of progression to advanced AMD," the researchers wrote. "Smoking and obesity were significantly related to both CRP and IL-6 levels. Higher values of CRP and IL-6 were found to be significantly related to AMD independent of these biomarkers and other established risk factors. These results, together with our cross-sectional report of an association between AMD and CRP and previous research on the topic, may shed light on the mechanisms and pathogenesis of AMD developments and prognosis. Anti-inflammatory agents may have a role in preventing AMD, and inflammatory biomarkers may provide a method of identifying people for whom these agents would be more or less effective."
The prospective cohort study began in 1989 and included 251 participants aged 60 and older who had some sign of nonexudative AMD and visual acuity of 20/200 or better in at least one eye at baseline. The AMD status was assessed by standardized grading of fundus photographs. Stored fasting blood specimens obtained at baseline were analyzed for levels of the various biomarkers. The average follow-up time was 4.6 years.
Dr. Seddon and her colleagues have previously established that smoking and nutrition are modifiable factors associated with the development and progression of AMD. They are now also searching for the genes involved in the etiology of this increasing cause of blindness.
This research was funded by grants from the Foundation Fighting Blindness, the Massachusetts Lions Eye Research Fund Inc., the Epidemiology Unit Research Fund of the MEEI, Boston, DSM Inc., of Parsippany, NJ, and in part by a grant from the National Eye Institute, Bethesda, MD, and by a Lew R. Wasserman Merit Award from Research to Prevent Blindness, Inc., NY.
About the Massachusetts Eye and Ear Infirmary, http://www.meei.harvard.edu The Massachusetts Eye and Ear Infirmary, an independent specialty hospital, is an international center for treatment and research and a teaching hospital of Harvard Medical School. - Boston (June 15, 2005)