Renoprotective effects of clarithromycin via reduction of urinary MCP-1 levels in type 2 diabetic patients

Background: Recent studies have shown the involvement of microinflammation in the pathogenesis of diabetic nephropathy. We previously demonstrated that erythromycin, one of the macrolides, ameliorated renal injury via anti-inflammatory effects in experimental diabetic rats. We conducted an open randomized controlled pilot study to investigate the renoprotective effect of clarithromycin for diabetic nephropathy in type 2 diabetic patients manifesting albuminuria. Methods: Sixteen patients were randomly assigned to the control (n = 8) or the CAM group in which they received 200 mg/day of clarithromycin (n = 8). At the beginning of the study and after 3 months of investigation, the following parameters were assessed: urinary albumin creatinine ratio (ACR), the levels of serum MCP-1, soluble ICAM-1, IL-18, IL-6 and hs-CRP, and the levels of urinary MCP-1 and IL-18. Results: The changes in urinary ACR were significantly improved (P = 0.039), and serum creatinine levels showed a decreasing trend (P = 0.053) in the CAM group compared with the control group. Urinary MCP-1 levels were significantly reduced in the clarithromycin-administrated group (P = 0.009). However, there was no significant difference in other proinflammatory markers. A significant positive correlation was obtained between the post-to-pre-urinary ACR and the post-to-pre-urinary MCP-1 ratio(r = 0.526, P = 0.043). In the CAM group, the changes of serum creatinine also showed a significant positive correlation with those of urinary ACR, urinary MCP-1, urinary IL-18 and serum levels of soluble ICAM-1. Conclusion: The results from our study suggest that clarithromycin may attenuate the production of renal MCP-1 in type 2 diabetic patients, resulting in amelioration of urinary ACR via anti-inflammatory effects. Modulation of microinflammation with clarithromycin may provide a new approach for diabetic nephropathy.