The changes of serum sKlotho and NGAL levels and their correlation in type 2 diabetes mellitus patients with different stages of urinary albumin

Objective: To investigate the changes of serum anti-aging protein Klotho and neutrophil gelatinase-associated lipocalin (NGAL) levels and their correlation in type 2 diabetes mellitus (T2DM) patients at different stages of diabetic kidney disease (DKD) determined by urinary albuminuria. Methods: 462 cases with T2DM were divided into three groups: normoalbuminuric [N-UAlb; urinary albumin to creatinine ratio (UACR) < 30 mg/g, n = 180], microalbuminuric [M-UAlb; UACR 30-300 mg/g, n = 158], macroalbuminuric [L-UAlb; UACR > 300 mg/g, n = 124]. The levels of serum soluble-Klotho (sKlotho), NGAL, 8-isoprostane prostaglandin F2 alpha (8-iso-PGF2 alpha), monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta 1 (TGF-beta 1) were determined by enzyme-linked immunosorbent assay (ELISA) in all cases and 160 control subjects. Results: Compared with control, serum sKlotho levels were significantly decreased (P < 0.001), and serum NGAL levels increased significantly (P < 0.001) in T2DM patients. Furthermore, serum sKlotho and NGAL levels were significantly negatively correlated (P < 0.001). Serum sKlotho levels negatively correlated with UACR, TG, CHO, LDL, 8-Iso-PGF2 alpha, MCP-1, TNF-alpha, TGF-beta 1 (P < 0.001), but positively correlated with LDL (P < 0.001). Serum NGAL levels positively correlated with UACR, 8-Iso-PGF2 alpha, MCP-1, TNF-alpha, TGF-beta 1 (P < 0.001). In addition, serum NGAL levels and LDL were significantly positively correlated (P = 0.005), and HDL was significantly negatively correlated (P < 0.001). Conclusion: Serum Klotho and NGAL levels may become new biomarkers of the early diagnosis of DKD in T2DM. Klotho may participate in the development of DKD pathological mechanism such as oxidative stress related to inflammation, renal fibrosis, lipid metabolic disorders, modulating the pathological process of diabetic kidney tissue. NGAL may play a part in these mechanisms. (C) 2014 Elsevier Ireland Ltd. All rights reserved.