title: Possible relationship between adiponectin and renal tubular injury in diabetic nephropathy.
abstract: Adiponectin is an adipose-derived protein which has anti-inflammatory and anti-atherogenic properties in addition to insulin-sensitizing effects. To date, the role of adiponectin in the pathogenesis of diabetic nephropathy remains unclear. The aim of the present study was to explore the relationship between adiponectin and renal tubular injury in diabetic nephropathy. We determined serum and urinary adiponectin levels in type 2 diabetic patients with normoalbuminuria (n = 19), microalbuminuria (n = 18), and overt diabetic nephropathy (n = 16), and then analyzed the correlations between serum and urinary adiponectin, urinary N-acetylglucosaminidase (NAG) as a clinical marker of renal tubular injury, urinary monocyte chemoattractant protein-1 (MCP-1) as an inflammatory marker in renal tubulointerstitium, and clinical markers of renal disease. Notably, serum and urinary adiponectin levels were significantly increased in patients with overt diabetic nephropathy compared to those with normoalbuminuria and microalbuminuria. In univariate linear regression analysis, serum adiponectin levels were positively correlated with serum creatinine (r = 0.648, P<0.0001), urinary albumin (r = 0.583, P<0.0001), urinary NAG (r = 0.406, P<0.01), urinary MCP-1 (r = 0.514, P<0.0001), and urinary adiponectin (r = 0.691, P<0.0001) levels in all diabetic patients. Urinary adiponectin levels were also positively correlated with serum creatinine (r = 0.729, P<0.0001), urinary albumin (r = 0.799, P<0.0001), urinary NAG (r = 0.701, P<0.0001), and urinary MCP-1 (r = 0.801, P<0.0001) levels in all diabetic patients. Multiple linear regression analysis showed that serum creatinine and urinary adiponectin levels were independently associated with serum adiponectin levels (r(2) = 0.522), and that serum creatinine, urinary NAG, urinary MCP-1, and serum adiponectin levels were independent determinants of urinary adiponectin levels (r(2) = 0.851). These results collectively indicate that renal insufficiency and tubular injury possibly play a contributory role in increases in serum and urinary adiponectin levels in overt diabetic nephropathy. We presume that an increase in circulating adiponectin in overt diabetic nephropathy might be a physiological response to mitigate renal tubular injury and to prevent the further progression of diabetic nephropathy through its anti-inflammatory and anti-atherogenic effects.
authors.affiliation: Division of Endocrinology, Metabolism, and Geriatric Medicine, Department of Internal Medicine, Akita University School of Medicine, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fujita
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Morii
authors.forename: Jun
authors.initials: J
authors.lastname: Koshimura
authors.forename: Motoko
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Masako
authors.initials: M
authors.lastname: Kato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasaki
authors.forename: Takuma
authors.initials: T
authors.lastname: Narita
authors.forename: Seiki
authors.initials: S
authors.lastname: Ito
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kakei
mesh_terms: D000118:Acetylglucosaminidase / Q000652:urine; D052242:Adiponectin / Q000097:blood* / Q000652:urine*; D000368:Aged; D000419:Albuminuria; D018932:Chemokine CCL2 / Q000652:urine; D003404:Creatinine / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000503:physiopathology / Q000652:urine; D003928:Diabetic Nephropathies / Q000097:blood* / Q000503:physiopathology / Q000652:urine*; D005260:Female; D006801:Humans; D007684:Kidney Tubules / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged
chemical_list: D052242:Adiponectin; C111835:CCL2 protein, human; D018932:Chemokine CCL2; D003404:Creatinine; D000118:Acetylglucosaminidase