[Influence of high glucose and mannose binding lectin complement pathway activation to IL-6 and TNF-alpha's expression by human renal glomerular endothelial cells].

Objective: To investigate the effect of high glucose and mannose binding lectin (MBL) complement pathway activation's effect on expression of Interleukin-6 (IL-6) and Tumor necrosis factor-alpha (TNF-alpha) from human renal glomerular endothelial cells (HRGEC), to explore unknown pathogenesy of diabetic nephropathy.

Methods: Normal HRGEC was divided randomly into normal glucose group(5 mmol/L D-glucose), manicol group (5 mmol/L D-glucose+25 mmol/L manicol) and high glucose group (30 mmol/L D-glucose). Real-time PCR was used to detect IL-6 and TNF-alpha mRNA expression in each group, Euzymelinked Immunosorbent Assay (ELISA) was performed to examine the protein expression of IL-6 and TNF-alpha in supernatant after 24 hours' culture. HRGEC was then randomly divided into two groups: single high glucose group and high glucose + MBL group. After 24 hours' culture with 30 mmol/L D-glucose, 30% MBL deficiency human serum was added into two groups, 1 microg/mL MBL was only added into high glucose + MBL group, continued the culturation for another 4 hours. Flow cytometry and immunofluorescence technique were applied to evaluate MBL, C3 and membrane attacks complex (MAC) deposition on cell surface respectively. Real-time PCR and ELISA were performed to examine mRNA and protein expression of both IL-6 and TNF-alpha in each group.

Results: Compared with normal glucose group and manicol group, the mRNA and protein expression of IL-6 and TNF-alpha in high glucose group were increased (P < 0.05). Flow cytometry confirmed obvious MBL and C3 co-deposition and Immunofluorescence confirmed obvious MAC deposition on cell surface in high glucose+ MBL group. Compared with single high glucose group, the mRNA and protein expression of IL-6 and TNF-alpha in high glucose+ MBL group were significantly higher (P < 0.05).

Conclusion: High glucose can bring inflammatory factors' overexpression from cultured HRGEC; high glucose together with MBL can bring MBL complement pathway activation and inflammatory factors' overexpression, this indicates that the activation of MBL complement pathway may be a potential unknown pathogenesy of diabetic nephropathy and its proinflammatory status.