Functional Polymorphisms In The Nuclear Factor E2-related Factor2(Nrf2) Gene And Serum Heme Oxygenase-1(HO-1) Activity With Vitiligo

Vitiligo is more common clinical pigment disorders of the skin, mainly involvingepidermal melanocytes. Although the exact pathogenic mechanisms underlying vitiligoremain obscure, accumulating evidence has demonstrated that a series of oxidative stress,particularly resulting in melanocyte damage or apoptosis, plays a major role in vitiligo.As the largest organ, skin is exposed to the external environment, when subjected to avariety of noxious stimuli, resulting in skin abnormal accumulation of oxygen freeradicals cause oxidative stress. The individual who has pathogenic genetic background,the ability of melanocytes against oxidative stimulation decreased sharply. Eventually,excess oxygen free radicals and cause melanocytes DNA damage. The increasedepidermal oxidative stress in the cutaneous epidermis of vitiligo patients and suggestingthat increased prooxidant activities and reduced antioxidant activities can lead to elevatedlevels of H2O2。Nuclear factor E2-related factor2(NRF2) is an important transcription factorregulating cellular antioxidant, its deletion or activation barrier will increase cell sensitivity to oxidative stress, resulting in cell dysfunction or death.NRF2/ARE signalingpathway downstream target of antioxidant genes heme oxygenase1(Heme oxygenases-1,HO-1) genes play a major antioxidant in the melanocytes, which could protect themelanocyte cells against oxidative stress. To the best of our knowledge, there is noresearch focusing on the relationship between the NRF2other loci and HO-1functionalpolymorphisms and the risk of vitiligo, besides Guan research found that the NRF2promoter650(C/A) loci related to vitiligo.Therefore, we hypothesized that the NRF2and the HO-1polymorphisms wereassociated with the susceptibility to vitiligo in the Han Chinese population, and testedthis hypothesis in our hospital-based case-control study of1000vitiligo patients and1000vitiligo-free control subjects. We further analyzed the function of a NRF2polymorphism in the region of promoter.MethodsIn this hospital-based case-control study of1000vitiligo patients and1000vitiligo-free age-and sex-matched controls, we genotyped4single nucleotidepolymorphisms (SNPs) of the NRF2(rs6721961, rs35652124, and rs10183914) andHO-1gene (rs2071746) respectively by performing polymerase chain reaction withsequence-specifc primers (PCR-SSP). Reporter gene assays are used to determine effectsof promoter mutations on transcriptional activity of the gene. HO-1assay kits are used todetect the serum HO-1activity in differential samples.Results1. We did not find any statistical correlation among NRF2rs6721961, HO-1rs2071746and the risk for developing vitiligo. The (CT+TT) genotype of NRF2rs10183914only showed a borderline increased vitiligo risk (P=0.057, adjusted OR1.30,95%Cl0.99-1.69).2. A significantly decreased risk of vitiligo susceptibility was associated with foundto be associated with the TT genotype of NRF2rs35652124(adjusted OR0.75,95%CI0.89-1.31).3. The combined genotype impact on the prevalence of risk analysis results show that: protective factor genotype as a reference, carrying the wild allele joint genotypefrequencies between vitiligo and control groups.4. The TT genotype frequency of NRF2rs35652124was signifcantly lower amongsubgroups, including onset age≤20years.5. The Linkage Disequilibrium tests showed that the two polymorphisms of NRF2gene were in Linkage Disequilibrium (D’=0.307, P <0.05for NRF2rs6721961andrs35652124), suggesting that joint effect between the two SNPs may exist.6. The serum HO-1activity in vitiligo patients’group is significantly higher than thatin the control. There were no obvious different among different genotype carriers.7. The in vitro luciferase assays in various cell lines further showed an decreasedtranscriptional activity of the rs35652124T allele compared with the G allele.A statistically signifcant decreased risk of vitiligo was found to be associated withthe GG genotype of rs35652124[odds ratio (OR)0.75,95%confidence interval (CI)0.89-1.31, P=0.031] as well as among subgroups: onset age≤20. The in vitro luciferaseassays in various cell lines further showed an decreased transcriptional activity of thers35652124G allele compared with the A allele. Moreover, the serum HO-1activity invitiligo patients’group is significantly higher than that in the control (P<0.001). Logisticregression analysis of serum HO-1activity showed an decreased risk trend (P=0.061)between lower activity and NRF2GG variant genotype carriers.Conclusion1. There was significant association of vitiligo risk with NRF2rs35652124. TheNRF2rs6721961, NRF2rs10183914and HO-1rs2071746gene might not play a majorrole in the pathogenesis of vitiligo.2. The NRF2rs35652124was associated with vitiligo, and had joint effect withNRF2rs6721961on vitiligo.3. The HO-1activity of serum was not only associate with vitiligo, but maycontribute to benefcial effects of clinic treatment for vitiligo patients in the future.4. NRF2gene polymorphisms may play an important role in the geneticsusceptibility to the development of vitiligo.