Role of serum IL-18 in type 2 diabetic patients with and without microalbuminuria

Abstract

Background: Microalbuminuria is a well-known indicator of poor renal outcomes in patients with type 2 diabetes that leads to diabetic nephropathy (DN), but there are many proinflammatary markers that are elevated during injury to the nephrons which lead to chronic kidney disease, one of those is interleukin - 18 (IL-18). Objective: To confirm the role of serum IL-18 as a novel predictor before DN onset. Patients and Methods: The microalbuminuria levels were measured by immunoturbidimetric method, serum IL-18 levels were measured by ELIZA sandwich method, both serum and urine creatinine levels were measured by colorimetric method and hemoglobin A1c (HbA1c) levels were measured by ion exchange - high performance liquid chromatography (HPLC) in 90 individuals, 20 individuals apparently healthy (group I), 40 diabetic patients without microalbuminuria (urinary albumin to creatinine ratio (UACR) ˂ 30 mg/g) (group II) and 30 diabetic with microalbuminuria (UACR 30 -300) (group III).Results: The mean of serum IL-18 in group I, II and III was 189.30 pg/ml ± 3.269 S.E., 220.83 pg/ml ± 0.900 S.E. and 246.67 pg/ml ± 22.341 S.E. respectively. The difference between group I and II, group I and III, and group II and III was significant (P=0.000 for all). The mean of UACR in group I, II and III was 4.25 mg/g ± 2.359 S.E., 4.20 mg/g ± 1.518 S.E. and 34.17 mg/g ± 0.629 S.E. respectively. The difference between group I and II was not significant (P=1. 000) but between group I and III, and group II and III were significant (P=0. 000 for both). The mean of serum creatinine in group I, II and III was 0.885 mg/dl ± 0.0302 S.E., 0.883 mg/dl ± 0.0240 S.E. and 0.933 mg/dl ± 0.0237 S.E. respectively. The difference between group I and II, group I and III, and group II and III was not significant (P=0.998, 0.331 and 0.145 respectively). The mean of hemoglobin A1c (HbA1c) in group I, II and III was 5.9 % ± 0.0211 S.E., 7.7 % ± 0.0445 S.E. and 8.135 % ± 0.0519 S.E. respectively. The difference between group I and II, group I and III, and group II and III was significant (P=0.000 for all). The correlation between urinary albumin to creatinine ratio (UACR) and IL-18 in group III was significant (r=0.983 with P=0.000). The correlation between hemoglobin A1c and IL-18 was significant (r=0.641 with P=0.000) in group II. The correlation between serum creatinine and IL-18 in group III was not significant (r=0.041 with P=0.830). Conclusion: while the increased IL-18 levels were positively correlated with both HbA1c and UACR that leads to the progression of the diabetic nephropathy and it can be one of the cytokines which opens the possibility of its application in clinical treatment in the future.