Association of <i>PSMB8</i> and <i>TAP1</i> polymorphisms in patients with vitiligo from Gujarat.

<p>Association of <i>PSMB8</i> and <i>TAP1</i> polymorphisms in patients with vitiligo from Gujarat.</p

Association of <i>PSMB8</i> and <i>TAP1</i> polymorphisms in patients with generalized and localized vitiligo from Gujarat.

<p>Association of <i>PSMB8</i> and <i>TAP1</i> polymorphisms in patients with generalized and localized vitiligo from Gujarat.</p

Analysis of PSMB8 protein expression.

<p>Western blot analysis in PBMCs of healthy controls (n = 6) and patients with active GV (n = 7) revealed significant decrease (<i>p</i> = 0.0460) in expression of PSMB8 after normalization with Ponceau staining.</p

A case-control study on association of proteasome subunit beta 8 (<i>PSMB8</i>) and transporter associated with antigen processing 1 (<i>TAP1</i>) polymorphisms and their transcript levels in vitiligo from Gujarat

<div><p>Background</p><p>Autoimmunity has been implicated in the destruction of melanocytes from vitiligo skin. Major histocompatibility complex (MHC) class-II linked genes proteasome subunit beta 8 <i>(PSMB8)</i> and transporter associated with antigen processing 1 <i>(TAP1)</i>, involved in antigen processing and presentation have been reported to be associated with several autoimmune diseases including vitiligo.</p><p>Objectives</p><p>To explore <i>PSMB8</i> rs2071464 and <i>TAP1</i> rs1135216 single nucleotide polymorphisms and to estimate the expression of <i>PSMB8</i> and <i>TAP1</i> in patients with vitiligo and unaffected controls from Gujarat.</p><p>Methods</p><p><i>PSMB8</i> rs2071464 polymorphism was genotyped using polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) and <i>TAP1</i> rs1135216 polymorphism was genotyped by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) in 378 patients with vitiligo and 509 controls. Transcript levels of <i>PSMB8</i> and <i>TAP1</i> were measured in the PBMCs of 91 patients and 96 controls by using qPCR. Protein levels of PSMB8 were also determined by Western blot analysis.</p><p>Results</p><p>The frequency of ‘TT’ genotype of <i>PSMB8</i> polymorphism was significantly lowered in patients with generalized and active vitiligo (<i>p =</i> 0.019 and <i>p =</i> 0.005) as compared to controls suggesting its association with the activity of the disease. However, <i>TAP1</i> polymorphism was not associated with vitiligo susceptibility. A significant decrease in expression of <i>PSMB8</i> at both transcript level (<i>p</i> = 0.002) as well as protein level (<i>p</i> = 0.0460) was observed in vitiligo patients as compared to controls. No significant difference was observed between patients and controls for <i>TAP1</i> transcripts (<i>p</i> = 0.553). Interestingly, individuals with the susceptible CC genotype of <i>PSMB8</i> polymorphism showed significantly reduced <i>PSMB8</i> transcript level as compared to that of CT and TT genotypes (<i>p</i> = 0.009 and <i>p</i> = 0.003 respectively).</p><p>Conclusions</p><p><i>PSMB8</i> rs2071464 was associated with generalized and active vitiligo from Gujarat whereas <i>TAP1</i> rs1135216 showed no association. The down-regulation of <i>PSMB8</i> in patients with risk genotype ‘CC’ advocates the vital role of <i>PSMB8</i> in the autoimmune basis of vitiligo.</p></div

<i>In silico</i> prediction results for <i>PSMB8</i> rs2071464 polymorphism.

<p><i>In silico</i> prediction results for <i>PSMB8</i> rs2071464 polymorphism.</p

Distribution of haplotypes frequencies for <i>PSMB8</i> (C/T) and <i>TAP1</i> (A/G) polymorphisms in vitiligo patients and controls.

<p>Distribution of haplotypes frequencies for <i>PSMB8</i> (C/T) and <i>TAP1</i> (A/G) polymorphisms in vitiligo patients and controls.</p

Relative gene expression of <i>TAP1</i> in patients and controls.

<p>(A) Expression of <i>TAP1</i> transcripts in 96 controls, 91 patients with vitiligo was analyzed by applying unpaired t-test. No significant difference in transcript levels of <i>TAP1</i> was observed as compared to controls (mean ΔCp ± SEM 5.59 ± 0.188 vs 5.421 ± 0.228; <i>p</i> = 0.553). Expression of <i>TAP1</i> transcripts in controls and patients with vitiligo showed approximately 1.12-fold change (NS) as determined by the 2^-ΔΔCp method. (B) Expression of <i>TAP1</i> transcripts in 96 controls and 72 patients with GV and 19 patients with LV was analyzed by using one-way ANOVA. Patients with GV and LV showed no significant difference in <i>TAP1</i> transcript levels as compared with controls (<i>p</i> = 0.856 and <i>p</i> = 0.090, respectively). No significant difference in <i>TAP1</i> transcript levels was observed between GV and LV (<i>p</i> = 0.219). (C) Expression of <i>TAP1</i> transcripts in 96 controls and 69 patients with AV and 22 patients with SV was analyzed by using one-way ANOVA. Patients with AV and SV showed no significant difference in <i>TAP1</i> transcripts levels as compared with controls (<i>p</i> = 0.671 and <i>p</i> = 0.291, respectively). No significant difference in <i>TAP1</i> transcript levels was observed among patients with AV and SV (<i>p</i> = 0.634). (D) Expression of <i>TAP1</i> transcripts with respect to different age of onset groups in 91 patients with vitiligo was analyzed by using one-way ANOVA. No significant difference in <i>TAP1</i> transcripts levels was observed in patients with respect to different age of onset groups. (F) Expression of <i>TAP1</i> transcripts with respect to sex differences in 48 male patients and 43 female patients was analyzed by applying unpaired t-test. No significant difference was observed in both the groups (<i>p</i> = 0.444).</p

Relative gene expression of <i>PSMB8</i> in cases and controls.

<p>(A) Expression of <i>PSMB8</i> transcripts in 96 controls (52 male and 44 female), 91 patients with vitiligo (48 male and 43 female) was analyzed by applying unpaired t-test. Patients showed a significant decrease in transcript levels of <i>PSMB8</i> compared to controls (mean ΔCp ± SEM: 8.958±0.239 vs 10.01 ± 0.229; <i>p</i> = 0.002). Expression of <i>PSMB8</i> transcripts in patients against controls showed 0.52 -fold decrease as determined by the 2^-ΔΔCp method. (B) Expression of <i>PSMB8</i> transcripts in 96 controls and 72 patients with GV and 19 patients with LV was analyzed by using one-way ANOVA. Patients with GV showed significantly decreased <i>PSMB8</i> transcript levels as compared to controls (<i>p</i> = 0.007). However, there was no significant difference in <i>PSMB8</i> transcript levels between patients with GV and LV as well as in patients with LV as compared to controls (<i>p</i> = 0.975 and <i>p</i> = 0.090, respectively). (C) Expression of <i>PSMB8</i> transcripts in 96 controls and 69 patients with AV and 22 patients with SV was analyzed by using one-way ANOVA. Patients with AV showed significantly decreased <i>PSMB8</i> transcript levels as compared to controls (<i>p</i> = 0.006). However, there was no significant difference in <i>PSMB8</i> transcript levels between patients with AV and SV as well as in patients with SV as compared to controls (<i>p</i> = 0.999 and <i>p</i> = 0.112, respectively). (D) Expression of <i>PSMB8</i> transcripts with respect to different age of onset groups in 91 patients with vitiligo was analyzed by using one-way ANOVA. No significant difference in <i>PSMB8</i> transcript levels was observed in patients with respect to different age of onset groups. (E) Expression of <i>PSMB8</i> transcripts with respect to sex differences in 48 male and 43 female patients was analyzed by applying unpaired t-test. No significant difference was observed in both the groups (<i>p</i> = 0.396). (F) Expression of <i>PSMB8</i> transcripts with respect to the <i>PSMB8</i> rs2071464 SNP in 96 controls and 91 patients was analyzed by using one-way ANOVA. Individuals with the CC genotype showed decreased <i>PSMB8</i> transcripts when compared with CT and TT genotypes (<i>p</i> = 0.009 and <i>p</i> = 0.003, respectively). No significant difference in <i>PSMB8</i> transcripts levels was observed in individuals with the CT and TT genotypes (<i>p</i> = 0.448).</p