Urinary inflammatory cytokines as indicators of kidney damage in type 2 diabetic patients

• Diabetic kidney disease (DKD) is characterized by persistent albuminuria.
• Some patients with diabetes have renal dysfunction even in a normoalbuminuric range.
• Inflammatory cytokines play a role in the development and progression of DKD.
• Urinary levels of IL-1 and IL-6 are altered in diabetic normoalbuminuric patients.
• Urinary inflammatory cytokines are able to identify DKD in type 2 diabetes patients.

BackgroundThe aim of this study was to investigate whether urinary levels of interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) are altered in normoalbuminuric patients with type 2 diabetes mellitus (T2DM), and whether these cytokines are able to identify diabetic kidney disease (DKD) among these patients.MethodsThis study included 125 T2DM patients classified into 3 groups according to urinary albumin/creatinine ratio (uACR): uACR < 10 mg/g creatinine, uACR 10–30 mg/g creatinine and uACR > 30 mg/g creatinine. Urinary inflammatory cytokines were measured.ResultsThe urinary IL-6 concentrations increased from uACR < 10 (97.2 ± 26.4 pg/ml) to uACR 10–30 (113.6 ± 28.0 pg/ml) and to uACR > 30 mg/g creatinine (163.5 ± 25.6 pg/ml) (P < 0.05 and P < 0.001, respectively) patients. The urinary IL-10 concentrations decreased in these uACR ranges [100.0 (58.0–141.0) pg/ml vs. 62.0 (54.5–71.5) pg/ml vs. 42.0 (32.0–48.0) pg/ml] (P < 0.05 and P < 0.001, respectively). All urinary cytokines demonstrated good ability to identify DKD (areas under curves > 0.9).ConclusionsUrinary inflammatory cytokines, especially IL-6 and IL-10, may assist in the identification of DKD in T2DM patients, even in the absence of micro- and macroalbuminuria.