Circulating Antimicrobial Peptide LL-37 Status in Type 1 Diabetes Mellitus and its Relation with Glycemic Control

Antimicrobial-peptides are important molecules of constitutive innate immunity. Though patients with diabetes mellitus are generally prone to infections, there is limited information on their antimicrobialpeptide status. We assessed the circulating LL-37 antimicrobial peptide (also referred as cathelicidin) levels in patients with type 1 diabetes mellitus and its relation with their glycemic status. The LL-37 mRNA expression was assessed in the peripheral blood mononuclear cells (PBMC) by quantitative RTPCR using s-actin and cytochrome-C1 as the reference genes in 154 subjects (Type 1 diabetes, n=111 and healthy subjects, n=43).  Serum LL-37 was quantified using sandwich-ELISA. Average HbA1c over last 2 years and current HbA1c were used to determine long-term and short-term glycemic status. LL-37 mRNA expression and serum LL-37 levels were correlated with the glycemic status. The LL-37 mRNA copies were comparable between type 1 diabetes and healthy subjects [median (IQR) = 6.7 (1.8–15.28) vs. 7.2 (2.23–21.86), respectively, P = 0.42]. There was no significant difference in serum LL-37 levels between the two groups [median (IQR) = 3.9 (2.88–7.52) vs. 5.0 (3.19–9.05) ng/ml, respectively, P = 0.52]. The LL-37 mRNA and its protein concentration showed no significant correlation with the average or current HbA1c values. The constitutive circulating antimicrobial peptide LL-37 status is not significantly altered in patients with type 1 diabetes mellitus and also not affected by their glycemic status.