Heat-shock protein 70-2 BB genotype is associated with reduced risks of the steroid-dependent and refractory phenotypes of ulcerative colitis

Previous studies have demonstrated the protective role of inducible heat-shock protein (HSP) 70 in intestinal cells. The HSP70-2 gene has a PstI site due to an A-G transition at the 1,267 position and different genotypes are associated with various levels of mRNA expression. The present study aimed to clarify the effect of the HSP70-2 polymorphism on the risk of ulcerative colitis (UC), including its clinical phenotypes. A total of 121 patients with UC and 500 healthy control (HC) subjects participated in the study. To assess the polymorphisms at the 1,267 position of the HSP70-2 gene, restriction fragment length polymorphism analysis was performed. The subjects in the study were classified by disease behavior, severity and extent of disease. Although no significant difference of the HSP70-2 genotype distribution was identified between the HC and UC groups, the BB genotype exhibited a lower risk of the steroid-dependent phenotype [odds ratio (OR), 0.12; 95% confidence interval (CI), 0.02-0.95; P=0.02]. The same genotype was also associated with a lower risk of the refractory phenotype (OR, 0.16; 95% CI, 0.04-0.73; P=0.01). There was no direct correlation between the polymorphism of the HSP70-2 gene and UC susceptibility. However, there was an association between a reduced risk of the steroid-dependent and refractory phenotypes of UC and the BB genotype.