The relationship between serum YKL-40 and endothelial dysfunction in chronic kidney disease

Chronic kidney disease (CKD) is an important public health problem in the world. Patients with CKD have greatly increased risks of cardiovascular events and cardiovascular deaths. Traditional cardiovascular risk factors can not explain the increased prevelance and incedence of this situation fully in CKD. Therefore, non-traditional risk factors have been investigated, such as endothelial dysfunction, oxidative stress, insulin resistance. Many inflammatory cytokines induce vascular inflammation and cause endothelial dysfunction. YKL-40,a secreted glycoprotein, is related to both acute and chronic inflammation and plays role in endothelial dysfunction. In this cross sectional study, we investigated relationship between endothelial dysfunction that plays an important role in the pathogenesis of cardiovascular events in patients with chronic kidney disease and YKL-40 a new pro-inflammatory molecule. 109 chronic kidney disease patients, 29 hemodialysis patients and 38 healthy controls were included in the study. There was no significant difference between the groups according to age, sex distribution and smoking status. (p>0,05). There was no significant difference between CKD and HD groups according to concomitant diseases (diabetes mellitus, hypertension, cardiovascular disease) (p>0,05) YKL-40 levels were significantly lower in healthy subjects (31,73 ±21,12) compared to CKD (55,98 ±22,96) and HD patients (83,91 ±16,88) (p<0,001) Flow Mediated Dilatation(FMD) percentages which are used as an indicator of endothelial dysfunction were significantly higher in healthy subjects (%13,24±6,34) compared to CKD (%4,82±3,79) and HD patients (%2,97±2,73) (p<0,001). There was a significant negative correlation between serum YKL-40 and GFR. (r=-0,674, p<0,001) . YKL-40 levels were also negatively correlated with FMD percentages, albumin, hemoglobin and HDL cholesterol. FMD percentages decreased with increasing levels of YKL-40. (r=-0,471, p<0,001). YKL-40 levels were in significant and positive correlation with CRP, uric acid and triglyceride levels. There was a weak positive correlation between YKL-40 and age. In conclusion, we found that YKL-40 was increased in a linear relationship with CKD stage. YKL-40 levels were in negative correlation with FMD measurements which used as an indicator of endothelial dysfunction. Also, YKL-40 levels were positively correlated with CRP levels that commonly used inflammatory markers; negatively correlated with albumin levels. These data can indicate YKL-40 is an useful marker to evaluate vascular proinflammatory process and endothelial dysfunction that considered as a predictor of cardiovascular disease in chronic kidney disease patients. Key words: Chronic Kidney Disease, Endothelial Dysfuncion, YKL-40