Polymorphisms in corticotrophin-releasing hormone-proopiomalanocortin (CRH-POMC) system genes: Neuroimmune contributions to psoriasis disease.

BACKGROUND: Skin is a target organ and source of the corticotropin-releasing hormone-proopiomelanocortin (CRH-POMC) system, operating as a coordinator and executor of responses to stress. Environmental stress exacerbates and triggers inflammatory skin diseases through modifying the cellular components of the immune system supporting the importance of CRH-POMC system in the pathogenesis of psoriasis. The aim of this study was to analyse the association of CRH-POMC polymorphisms with psoriasis and evaluate transcript expression of lesional psoriatic and normal skin in RNA-seq data. METHODS: Samples of 104 patients with psoriasis and 174 healthy controls were genotyped for 42 single nucleotide polymorphisms (SNPs) of CRH-POMC using Applied Biosystems SNPlex™ method. The transcript quantification was performed using Salmon software v1.3.0. RESULTS: This study demonstrated the associations between melanocortin 1 receptor (MC1R) polymorphisms rs2228479, rs3212369, dopachrome tautomerase (DCT) polymorphisms rs7987802, rs2031526, rs9524501 and psoriasis in the Tatar population. Very strong association was evident for the SNP rs7987802 in the DCT gene (pc = 5.95е-006) in psoriasis patients. Additionally, the haplotype analysis provided AT DCT (rs7992630 and rs7987802) and AGA MC1R (rs3212358, 2228479 and 885479) haplotypes significantly associated (pc ˂ 0.05) with psoriasis in the Tatar population, supporting the involvement of DCT and MC1R to the psoriasis susceptibility. Moreover, MC1R-203 and DCT-201 expression levels were decreased in psoriasis lesional skin compared with healthy control skin. CONCLUSIONS: This study is the first to identify genetic variants of the MC1R and DCT genes significantly associated with psoriasis in Tatar population. Our results support potential roles of CRH-POMC system genes and DCT in the pathogenesis of psoriasis.

Association analysis of class II cytokine and receptor genes in vitiligo patients.

The loss of melanocytes in vitiligo is mainly attributed to defective autoimmune mechanisms and lately autoinflammatory mediators have become more emphasized. Among these, a number of class II cytokines and their receptors have displayed altered expression patterns in vitiligo. Thus, we selected 30 SNPs from the regions of respective genes to be genotyped in Estonian case-control sample (109 and 328 individuals, respectively). For more precise analyses, patients were divided into subgroups based on vitiligo progression activity, age of onset, sex, occurrence of vitiligo among relatives, extent of depigmented areas, appearance of Köbner's phenomenon, existence of halo nevi, occurrence of spontaneous repigmentation, and amount of thyroid peroxidase antibodies. No associations appeared in whole vitiligo group. In subgroups, several allelic and haplotype associations were found. The strongest involved SNPs rs12301088 (near IL26 gene), that was associated with familial vitiligo and existence of halo nevi, and rs2257167 (IFNAR1 gene), that was associated with female vitiligo. Additionally, haplotypes consisting of rs12301088 and rs12321603 alleles (IL26-IL22 genes), that were associated with familial vitiligo and existence of halo nevi. In conclusion, several genetic associations with vitiligo subphenotypes were revealed and functional explanations to these remain to be determined in respective studies.

Polymorphisms in Toll-like receptor genes are associated with vitiligo.

BACKGROUND: The members of Toll-like receptor (TLR) family are responsible for recognizing various molecular patterns associated with pathogens. Their expression is not confined to immune cells and have been detected in skin cells such as keratinocytes and melanocytes. As part of a generated response to pathogens, TLRs are involved in inducing inflammatory mediators to combat these threats. It is therefore not surprising that TLRs have been implicated in inflammatory skin diseases, including atopic dermatitis and psoriasis. Likewise, as key players in autoimmunity, they have been associated with a number of autoimmune diseases. Based on this, the role of TLRs in vitiligo could be suspected, but is yet to be clearly established. METHODS: In order to conduct a genetic association analysis, 30 SNPs were selected from TLR1-TLR8 and TLR10 regions to be genotyped in Estonian case-control cohort consisting of 139 vitiligo patients and 307 healthy control individuals. The patients were further analyzed in subgroups based on sex, age of onset, occurrence of vitiligo among relatives, extent of depigmented areas, vitiligo progression activity, appearance of Köbner's phenomenon, existence of halo naevi, and incidence of spontaneous repigmentation. RESULTS: The most notable finding came with SNP rs179020 situated in TLR7 gene, that was associated in entire vitiligo (Padj = 0.0065) and also several subgroup analyses. Other single marker and haplotype analyses pointed to TLR3, TLR4, and TLR10 genes. CONCLUSIONS: This study investigated the genetic regions of nine TLR genes in relation to vitiligo susceptibility. The main results were the associations of TLR7 SNPs with vitiligo, while several other associations were obtained from the remaining TLR gene regions. This suggests that in addition to other inflammatory skin diseases, TLRs affect the development of vitiligo, thus making them interesting targets for future research.

Analysis of genetic variants of class II cytokine and their receptor genes in psoriasis patients of two ethnic groups from the Volga-Ural region of Russia.

BACKGROUND: The molecular basis of pathogenesis of psoriasis remains unclear, but one unifying hypothesis of disease aetiology is the cytokine network model. The class II cytokines (CF2) and their receptors (CRF2) are all involved in the inflammatory processes and single nucleotide polymorphisms (SNPs) in respective genes have been associated with psoriasis in a previous study of the Estonian population. OBJECTIVE: We performed a replication study of 47 SNPs in CF2 and CRF2 genes in independent cohorts of psoriasis patients of two ethnic groups (Russians and Bashkirs) from the Volga-Ural region of Russia. METHODS: DNA was obtained from 395 psoriasis patients of two ethnic groups from the Volga-Ural region of Russia and 476 ethnically matched controls. 47 SNPs in the loci of the genes encoding Class II cytokines and their receptors were selected by SNPbrowser version 3.5. Genotyping was performed using the SNPlex™ (Applied Biosystems) platform. RESULTS: The genetic variant rs30461 previously associated in original case-control study in Estonians, was also associated in Russians (corrected P-value (Pc=0.008, OR=0.44), but did not reach statistical significance in the Bashkir population. Additionally, the haplotype analysis provided that CC haplotype formed by the SNPs rs30461 and rs955155 had a protective effect in Russians (Pc=0.0024, OR=0.44), supporting the involvement of this locus in the protection against psoriasis. Combined meta-analysis of three populations, including 943 psoriasis patients and 812 healthy controls, showed that the IL29 rs30461 C-allele was not associated with decreased risk of psoriasis (P=0.165, OR=0.68). Moreover, stratification of studies by ethnicity revealed a significant association in the European cohort (P=9.506E-006, OR=0.53). CONCLUSION: Therefore, there is no overall evidence of association between psoriasis and SNP rs30461 of the IL29 gene, but there is some evidence to suggest that an association exists in Europeans. However, this current concept should be considered as preliminary and the results need to be confirmed in future independent studies.

Balanced reciprocal translocation t(5;13)(q33;q12) and 9q31.1 microduplication in a man suffering from infertility and pollinosis.

We describe the first case of two chromosomal abnormalities, balanced reciprocal translocation t(5;13)(q33;q12.1) and a microduplication in the region 9q31.1, in a man suffering from infertility and pollinosis. In the region 13q12.1 is located the TUBA3C (tubulin, alpha 3c) gene, which plays an important dynamic role in the motility of flagella. This case might support the opinion that haploinsufficiency of the TUBA3C gene could be the cause of sperm immotility and abnormal sperm morphology, resulting in infertility in the patient. Single-nucleotide polymorphism (SNP) array analysis revealed a novel 9q31.1 microduplication inherited from both parents, which contributes to the genomic instability.

ATG16L1 gene polymorphisms are associated with palmoplantar pustulosis.

Genes in autophagy pathway play an important role in innate and adaptive immunity. The aim of the study was to assess the impact of ATG16L1 gene on susceptibility of palmoplantar pustulosis. Four single nucleotide polymorphisms (SNPs) within the ATG16L1 region (rs2241880, rs2241879, rs7587633, and rs13005285) were genotyped in 241 control subjects and 38 palmoplantar pustulosis (PPP) patients of Estonian descent. The data analysis revealed a significantly higher frequency distribution of the rs2241880 G (odds ratio [OR] = 1.88, p = 0.0073) and rs2241879 A (OR = 1.87, p = 0.0079) allele in the PPP group when compared with the control group. The frequency distribution of the GACG haplotype was significantly higher (OR = 1.82, p = 0.016) in the PPP group when compared with the control group. The current study provides evidence of an association of the ATG16L1 gene in susceptibility to palmoplantar pustulosis, and supports the notion that the ATG16L1 gene as a member of the autophagy pathway most likely plays an important role in immune response.

Association analysis of genes of the IL19 cluster and their receptors in vitiligo patients.

The aim of the present study was to explore whether the genes encoding interleukin (IL) 19, IL-20, IL-24 and 2 chains of the IL-20 receptor type I (IL-20-RI), IL-20RA and IL-20RB, located on chromosomes 1q32, 6q22­23 and 3q22, respectively, are associated with vitiligo. The study involved 76 patients with vitiligo and 236 unrelated healthy volunteers. Genomic DNA was extracted from the whole blood and the frequencies of 20 single nucleotide polymorphisms were analysed by tetraprimer amplification refractory mutation system polymerase chain reaction. The minor allele of IL19 rs2243188 was significantly increased in vitiligo patients compared to controls (53.3 vs. 28.6%, adjusted p < 0.0001). The haplotype analysis revealed associations of 2 IL19/IL20 extended haplotypes (AACGTAA and ACCGTAA) and 2 IL20RB haplotypes (AGTA and AGGA) with vitiligo, remaining significant after correction for multiple testing. The A-to-C exchange at position IL19 rs2243188 leads to the loss of a nuclear receptor subfamily 2 factor binding site that is thought to influence mouse hippocampal development and neuronal differentiation. The third position of the IL20RB haplotypes is taken by rs747842 that induces the loss of the interferon regulatory factor 4 binding site that has an important role in the regulation of innate and adaptive immunity and in the signalling of pigmentation as well. In conclusion, the present study describes first-time associations between polymorphisms of genes of the IL19 cluster and their receptors and vitiligo, indicative of the part of IL19 and its receptor gene IL20RB in disease pathogenesis.

Promoter polymorphism -119C/G in MYG1 (C12orf10) gene is related to vitiligo susceptibility and Arg4Gln affects mitochondrial entrance of Myg1.

BACKGROUND: MYG1 (Melanocyte proliferating gene 1, also C12orf10 in human) is a ubiquitous nucleo-mitochondrial protein, involved in early developmental processes and in adult stress/illness conditions. We recently showed that MYG1 mRNA expression is elevated in the skin of vitiligo patients. Our aim was to examine nine known polymorphisms in the MYG1 gene, to investigate their functionality, and to study their association with vitiligo susceptibility. METHODS: Nine single nucleotide polymorphisms (SNPs) in the MYG1 locus were investigated by SNPlex assay and/or sequencing in vitiligo patients (n = 124) and controls (n = 325). MYG1 expression in skin biopsies was detected by quantitative-real time PCR (Q-RT-PCR) and polymorphisms were further analysed using luciferase and YFP reporters in the cell culture. RESULTS: Control subjects with -119G promoter allele (rs1465073) exhibited significantly higher MYG1 mRNA levels than controls with -119C allele (P = 0.01). Higher activity of -119G promoter was confirmed by luciferase assay. Single marker association analysis showed that the -119G allele was more frequent in vitiligo patients (47.1%) compared to controls (39.3%, P < 0.05, OR 1.37, 95%CI 1.02-1.85). Analysis based on the stage of progression of the vitiligo revealed that the increased frequency of -119G allele occurred prevalently in the group of patients with active vitiligo (n = 86) compared to the control group (48.2% versus 39.3%, P < 0.05; OR 1.44, 95%CI 1.02-2.03). Additionally, we showed that glutamine in the fourth position (in Arg4Gln polymorphism) completely eliminated mitochondrial entrance of YFP-tagged Myg1 protein in cell culture. The analysis of available EST, cDNA and genomic DNA sequences revealed that Myg1 4Gln allele is remarkably present in human populations but is never detected in homozygous state according to the HapMap database. CONCLUSIONS: Our study demonstrated that both MYG1 promoter polymorphism -119C/G and Arg4Gln polymorphism in the mitochondrial signal of Myg1 have a functional impact on the regulation of the MYG1 gene and promoter polymorphism (-119C/G) is related with suspectibility for actively progressing vitiligo.

Expressional changes in the intracellular melanogenesis pathways and their possible role in the pathogenesis of vitiligo.

BACKGROUND: Main pathway in human melanocytes through which signal from the melanocortin system reaches the melanogenesis enzymes is cAMP/PKA pathway and it is modulated by Wnt and MAPK pathways. In our previous study we established significant increase of melanocortin receptor expression in unaffected skin of vitiligo patients compared to healthy subjects. OBJECTIVE: The aim of this study was to assess the gene expression profile of the intracellular signalling pathways linking melanocortin system with enzymes involved in melanogenesis. METHODS: Using QRT-PCR method, mRNA expression levels of eight genes related to signal transduction from the melanocortin system to melanogenesis enzymes was measured in lesional and non-lesional skin of vitiligo patients and in the skin of healthy control subjects. Following genes were analyzed in the study: MITF, CREB1, p38, USF1, PIK3CB (PI3K), RPS6KB1, LEF1 and BCL2. RESULTS: The mRNA levels of MITF, LEF1, p38, PIK3CB and RPS6KB1 were decreased in lesional skin of vitiligo patients compared to skin of healthy control subjects. We also found increased expression of USF1 and BCL2 in non-lesional skin of vitiligo patients compared to skin of healthy control subjects. mRNA levels of MITF and BCL2 were decreased in lesional skin of vitiligo patients compared to non-lesional skin of vitiligo patients. CONCLUSIONS: Present study indicates increased expression of the genes of the intracellular melanogenesis pathway in the non-lesional skin of vitiligo patients. This finding suggests activation of melanogenesis pathway in the non-lesional skin of vitiligo.

Gene expression analysis of melanocortin system in vitiligo.

BACKGROUND: The melanocortin system in the skin coordinates pigmentation and immune response and could be implicated in the pathogenesis of vitiligo. OBJECTIVES: We aimed to analyze changes in expression of genes involved in skin pigmentation (melanocortin system and enzymes involved in melanin synthesis). METHODS: With quantitative RT-PCR we measured the mRNA expression levels of eight genes from the melanocortin system and two enzymes involved in melanogenesis. RNA was extracted from both lesional and non-lesional skin of vitiligo patients and in non-sun-exposed skin of healthy subjects. RESULTS: POMC (proopiomelanocortin) expression was lower in lesional skin compared to non-lesional skin. Expression of melanocortin receptors was increased in unaffected skin of vitiligo patients compared to healthy subjects and decreased in lesional skin compared to uninvolved skin of vitiligo patients, the differences were statistically significant in the cases of MC1R (melanocortin receptor 1) and MC4R (melanocortin receptor 4). TRP1 and DCT genes were down-regulated in lesional skin compared to non-lesional vitiligo skin or skin of healthy controls and up-regulated in uninvolved vitiligo skin compared to healthy control samples. In non-lesional skin, POMC expression was not elevated, possibly indicating that systemic influences are involved in up-regulation of MC receptor genes. Decreased expression of the analyzed genes in the lesional skin is not surprising, but statistically significant increased expression of studied genes in non-lesional skin from vitiligo patients is not described previously. CONCLUSION: In our mind, up-regulation of melanocortin system in non-lesional skin could be systemic compensation to restore normal pigmentation in lesions.