P16 INTERCELLULAR ADHESION MOLECULE-1 K469E(A/G) POLYMORPHISM AND ITS EFFECTS IN THE DEVELOPMENT OF DIABETIC NEPHROPATHY

Abstract

Recent research has implicated that inflammation may be a key pathophysiological mechanism in diabetic nephropathy (DN), although its pathogenesis is multifactorial. Intercellular adhesion molecule 1 (ICAM-1) is an acute phase marker of inflammation and the ICAM-1 gene is located on chromosome 19p13.2 and resides a linkage region to diabetes and DN. To investigate whether ICAM-1 has effects in the development of DN, we have recently performed genetic and pathological studies of this molecule in Swedish and Malaysian subjects with normal glucose tolerance (NGT), diabetes and DN. We genotyped six single nucleotide polymorphisms (SNPs) in the ICAM-1 gene with TaqMan allelic discrimination. We also determined plasma ICAM-1 levels with an enzyme-linked immune-sorbent assay kit. We found that non-synonymous SNP rs5498 (K469E A/G) was associated diabetes and DN and the G allele had a protective effect. Particularly, we found a high heterozygous index of this polymorphism presenting in both populations. The genotype distribution of this polymorphism was kept in Hardy-Weinberg Equilibrium and no duplicon in the genomic sequence was found. The ICAM-1 K469E(A/G) polymorphism resides in the 5th Ig-like domain of ICAM-1 protein. This domain is essential for dimerization, surface presentation and solubilisation of proteins of the protein and subsequently plays a crucial role in the activity of ICAM-1 protein in the interaction with LFA-1 and the adhesion of B cells. Furthermore, we found the carriers with heterozygous genotype had higher fasting glucose levels among newly diagnosed type 2 diabetes patients compared with the subjects with wild or mutant homozygous genotype. Plasma ICAM-1 levels were increased from the subjects with NGT, diabetes without DN to the patients with DN. Among diabetic patients with DN, the carriers with heterozygous genotype had higher plasma ICAM-1 levels compared with other patients. Our study provided evidence that ICAM-1 has effects in the development of DN. The patients carrying with heterozygous genotype of SNP rs5498 (K469E A/G) in the ICAM-1 gene have higher risk susceptibility to DN. The combined approach with genotyping this polymorphism and measuring plasma ICAM-1 levels may be useful for prediction of DN in translation medicine.