Mannose-binding lectin activation is associated with the progression of diabetic nephropathy in type 2 diabetes mellitus patients

Background: We aimed to investigate whether mannose-binding lectin (MBL) activation contributed to the progression of diabetic nephropathy (DN), and its role in predicting the renal prognosis of DN. Methods: Seventy-seven patients who received renal biopsy in the First Affiliated Hospital, College of Medicine, Zhejiang University between August 2013 and September 2016 were enrolled in the study. These patients were followed up until the endpoint of end-stage renal disease (ESRD) or the last follow-up time of August 31, 2018. They were divided into ESRD group (33 patients) and non-ESRD group (44 patients). Their baseline characteristics and MBL levels (serum and urine) were compared between groups. The correlation between single nucleotide polymorphisms (SNPs) of the MBL2 gene and renal outcomes was also analyzed. Results: The median (interquartile ranges) of serum and urine MBL levels were significantly higher in ESRD group than those in non-ESRD group [2,783.75 (1,244.28, 3,837.07) vs. 1,141.60 (652.67, 3,188.44) ng/mL, P= 0.016; 1.02 (0.43, 2.05) vs. 0.27 (0.04, 0.58) ng/mg, P<0.01, respectively]. Both univariate and multivariate Cox analysis showed that serum MBL >1,108.75 ng/mL (stratified by maximum Youden index) was an independent predictor for ESRD [hazard ratio (HR) =4.164, 95% confidence interval (CI): 1.601-10.833, P=0.003; HR =4.644, 95% CI: 1.320-16.337, P=0.017; respectively]. For the patients with rs1800450 SNPs of MBL2 gene, patients with homozygous genotype (GG) had higher serum MBL level (median 2,963.52 ng/mL) compared with those with heterozygous genotype (GA) (median 665.38 ng/mL) (P<0.001). MBL2 rs1800450 GA genotype was an independent protective factor for ESRD with a HR of 0.485 (95% CI: 0.237-0.991; P=0.047). Conclusions: Activation of MBL contributed to the progression of DN. The rs1800450 SNP of the MBL2 gene may be of value in predicting the progression to ESRD in DN patients.