Genetic variations in NLRP1 and Glutathione S-Transferase are associated with Generalized Vitiligo of Phlegmatic Clinical Phenotypes in Unani Medicine Philosophy of South Indian Population

Abstract

Background: Generalized vitiligo is a common, multifaceted, polygenic condition in which autoimmune loss of melanocytes results in depigmented skin patches, overlying hair and mucous membranes. NLRP1 has been proposed to be implicated in the susceptibility of a broad variety of autoimmune disorders, including generalized vitiligo (GV). Genetic polymorphisms in the NLRP1 encoding gene (formerly known as NALP1) have previously been found to be linked with GV and there is uncertainty as to their role in the modulation of NLRP1 expression. Oxidative stress is a significant pathogenesis theory for vitiligo. Glutathione S-transferases (GSTs) are enzymes active in the defense of cells against chemical toxicity and stress.This study validates some of the Unani concepts of humors or temperaments (Phenotypes), with regard to Vitiligo, Where vitiligo is regarded as a phlegmatic disease. We selected Vitiligo subjects with Phlegmatic Clinical Phenotype for our study, with an aim to determine its association with the genetic biomarkers- NLRP1, GSTM1 and GSTT1 null genotypes and other biochemical parameters. Methods: The Unani clinicians randomly selected 100 vitiligo patients with a phlegmatic Clinical Phenotype who were attending NRIUMSD for treatment and 100 healthy volunteers belonging to Phlegmatic (Phlegmatic clinical Phenotype). Besides looking at temperaments/ humors as susceptibility factors – we included a genetic factor- NLRP1, GSTM1- and GSTT1-null genotypes to our investigation. We have genotyped the NLRP1, GSTM1- and GSTT1-null genotypes by PCR-RFLP and by Multiplex PCR, GST protein level estimation by ELISA method. Results: NLRP1 rs2670660 polymorphism was shown to be in significant association with GV, with the presence of minor alleles in active GV. We found that the frequencies of GSTM1 null genotype and GSTT1 null genotype in vitiligo patients were significantly high compared to the controls (OR= 1.47, 95% CI=0.765--2.861), (OR = 4.75, 95% CI = 2.131-10.63), respectively. In combination analysis with both genes, the results suggested significant association of vitiligo risk with both GSTM1\GSTT1 null genotypes (OR=4.83, 95% CI=1.523– 15.32).We observed a significant decrease (p<0.001) in GST protein levels. Conclusion: Our findings indicate that NLRP1 rs2670660 polymorphism may be genetic risk factor for susceptibility to GV and the null genotypes of GSTM1 and GSTT1 of both genes increase the risk of the disease. A significant decrease (p<0.001) in GST protein levels appeared to be a key feature in Vitiligo subjects, Therefore, detection of antioxidant enzyme levels can be effective biomarkers for early detection of the disease. We believed that GSTM1-and GSTT1-null genotype polymorphisms were associated with an increased risk of vitiligo. This is the first study of its kind along with Clinical Phenotype as per Unani Philosophy.