Abstract
Purpose: :
The ectodomain of CD44 (soluble CD44, sCD44) is an emerging novel aqueous marker of primary open-angle glaucoma (POAG). In the Ocular Hypertension Treatment Study (OHTS), diabetes was found to be protective against the progression of POAG. The purpose of this study was to determine the aqueous sCD44 concentration and level of acetylcholinesterase of diabetic patients who were also afflicted with POAG (diabetes/POAG).
Methods: :
Aqueous humor samples were obtained by paracentesis from patients undergoing elective surgery for cataracts or glaucoma and the study population were normal subjects, diabetes, diabetes/POAG with mild and moderate visual field loss, and POAG with mild and moderate visual field loss. Aqueous samples were analyzed by enzyme-linked immunosorbent assay (ELISA) for sCD44 and by Western blot analysis to determine the acetylcholinesterase level.
Results: :
The aqueous sCD44 concentration was: normal subjects, 5.95 ± 0.28 ng/ml (n=120); diabetes, 7.23 ± 0.84 (n=16); diabetes with POAG, 8.98 ± 1.34 (n=13); and POAG, 12.59 ± 0.78 (n=50). The difference in sCD44 concentration between diabetes/POAG and POAG patients was highly significant (P<0.003). Western blot analysis of acetylcholinesterase revealed the relative concentration of acetylcholinesterase was POAG > normal >diabetes> diabetes/POAG.
Conclusions: :
The aqueous concentration of sCD44 and the relative level of acetylcholinesterase were lower in diabetes/POAG than POAG. The reduction in sCD44 concentration in patients with diabetes/POAG may alter the POAG disease process since sCD44 is cytotoxic to trabecular meshwork and retinal ganglion cells in vitro. The decreased level of acetylcholinesterase in diabetes/POAG may also modify the disease process since its substrate acetylcholine is proinflammatory. This study demonstrates biochemical alterations in the aqueous of diabetes/POAG patients, lending support to the concept that diabetes may have a protective role in POAG.
Keywords: trabecular meshwork • diabetes • neuroprotection