Increased level of cathelicidin (LL‐37) in vitiligo: Possible pathway independent from vitamin D receptor gene polymorphism

Vitiligo is a multifactorial skin disease with established role of genetics and autoimmunity in its pathogenesis. Vitamin D receptor (VDR) polymorphisms have been suggested to correlate with risk of vitiligo in some ethnic populations. On the other hand, cathelicidin, one of the innate immune system components, has a role in development of some chronic skin diseases and VDR regulates the expression of cathelicidin. We aimed to determine the plasma level of cathelicidin and its association with the VDR gene polymorphisms as well as plasma vitamin D level in patients with vitiligo. Ninety vitiligo patients and 90 non-vitiligo controls participated in this study. Blood levels of 25(OH) vitamin D and cathelicidin were determined with ELISA. Genotyping for VDR polymorphisms (ApaI, TaqI, FokI and BsmI) was done with RFLP-PCR method. Mean blood level of cathelicidin was significantly higher in vitiligo patients as compared to controls (P<0.0001). Mean blood level of vitamin D was significantly lower in patients than controls (P=0.01). Statistically significant differences were not observed for both genotype and allele frequencies of BsmI, ApaI, and TaqI polymorphisms. There was a borderline increased risk of vitiligo in over-dominant model of FokI polymorphism with OR=1.8 and P=0.051. Our findings are suggestive of the potential role of cathelicidin in the pathogenesis of vitiligo; however, future evaluations are needed to determine precise mechanism. Genetic study of VDR polymorphism was suggestive of increased risk of vitiligo in association with a FokI polymorphism in the VDR gene in Iranian population.