Evaluation of YKL-40 levels in serum and aqueous humor in diabetic retinopathy

Background and Aim: The release of proinflammatory and angiogenic mediators as a result of chronic inflammation, hypoxia and ischemia plays an important role in the pathophysiology of diabetic retinopathy (DR). These mediators trigger vascular endothelial cell dysfunction and proliferation, leading to progression of DR severity. YKL-40 (chitinase-3-like protein 1), accepted as a new potential biomarker of DM, is a glycoprotein that is elevated in hypoxic ischemic and inflammatory conditions and has been shown to play a role in endothelial dysfunction and angiogenesis. In our study, it was aimed to determine the amount of YKL-40 in serum and aqueous samples of type 2 DM patients and to investigate its effect on DR severity. Methods: A total of 90 volunteers were included in our study, 23 of whom were in the control group, 26 from the non-DRP group, 21 from the NPDR group, and 20 from the PDR group. HbA1c, HDL, LDL, total cholesterol, triglyceride, CRP, fibrinogen values and serum and anterior chamber YKL-40 levels were studied. Results: According to the control group, serum and aqueous YKL-40 levels are higher in DM patients. As the severity of DR progresses, serum and aqueous YKL-40 levels increase. The serum YKL-40 level of the PDR group is higher than the non-DRP group (p=0.047). Aqueous YKL-40 levels is higher in the NPDR group than in the non-DRP group (p=0.013). The aqueous YKL-40 levels of the PDR group were found to be higher when compared to the NPDR group (p<0.001). According to the ROC analysis, the threshold value of aqueous YKL-40 in the transition from non-DRP to NPDR-PDR is 484.5 pg/ml (area under the curve= 0.83; p<0.001, 65% sensitivity and 88% specificity). A correlation was found between DM durations and aqueous YKL-40 values (r=.384 p=0.001). Conclusion: YKL-40 may be an important biomarker that plays a role in the progression of DR severity. In the future, agents to be developed against this biomarker can be used as an alternative in the treatment of DR. Keywords: DR; YKL-40; Chitinase; Vascular proliferation.