The Expression Pattern of Genes Related to Melanogenesis and Endogenous Opioids in Psoriasis.

The melanocortin system is a major regulator of stress responses in the skin and is responsible for the induction of melanin synthesis through activation of melanogenesis enzymes. The expression of both melanocortin system genes and melanogenesis enzyme genes is altered in psoriasis, and the focus here was on twelve genes related to the signal transduction between them. Additionally, five endogenous opioid system genes that are involved in cutaneous inflammation were examined. Quantitative real-time-PCR was utilized to measure mRNA expression in punch biopsies from lesional and non-lesional skin of psoriasis patients and from the skin of healthy control subjects. Most of the genes related to melanogenesis were down-regulated in patients (CREB1, MITF, LEF1, USF1, MAPK14, ICAM1, PIK3CB, RPS6KB1, KIT, and ATRN). Conversely, an up-regulation occurred in the case of opioids (PENK, PDYN, and PNOC). The suppression of genes related to melanogenesis is in agreement with the reported reduction in pigmentation signaling in psoriatic skin and potentially results from the pro-inflammatory environment. The increase in endogenous opioids can be associated with their involvement in inflammatory dysregulation in psoriasis.

Polymorphisms in IL36G gene are associated with plaque psoriasis.

BACKGROUND: Plaque psoriasis is a non-contagious skin disease in which characteristic red and flaky lesions result from a dysregulation involving both innate and adaptive immune mechanisms. Several cytokines have been implicated in these processes and lately interleukin (IL)-36 family members have become more recognised among them. Thus far, genetic studies have only investigated IL36RN gene of this family in relation to pustular psoriasis. Since IL36G has previously demonstrated markedly increased levels in plaque psoriasis patients and is linked to IL-23/IL-17 axis critical in psoriasis pathology, it was chosen to be the focus of current report. METHODS: Eleven SNPs from IL36G region were genotyped in 728 plaque psoriasis patients and 320 healthy control individuals. Allele and haplotype frequencies between patients and controls were assessed by respective association tests. For more specific analyses, the patients were assigned into subgroups according to sex, age of disease onset, occurrence of psoriasis among relatives, seasonal aggravation, arthritis symptoms, body surface area (BSA) scores, and Psoriasis Area and Severity Index (PASI) scores. RESULTS: The most significant results were obtained with SNPs rs28947206, rs28947207 and rs28947211 that were associated in entire plaque psoriasis analysis (multiple testing adjusted p value (padj) = 0.0054, padj = 0.0017 and padj = 0.0001) and also several subgroups. The first two of those SNPs were included in the same haplotype block with rs28947205 and rs12328178, and two of the respective haplotypes, CAGC and TGTT, provided similarly significant associations (padj = 0.0462 and padj = 0.0047). CONCLUSIONS: The associated SNPs of this study or those in linkage disequilibrium with them could potentially affect the functionality of IL-36γ cytokine, which in turn may impact plaque psoriasis pathology. For instance, these variants could influence IL-36γ expression or 3D structure, thereby altering its ability to induce chemokine production in keratinocytes and various immune cells. The precise mechanisms of these actions are currently unknown and out of the scope of this study. To conclude, the present genetic association results confirm the proposed role of IL-36γ in plaque psoriasis development, with corresponding causal effects to be determined in forthcoming research.

Transcriptional landscape of human endogenous retroviruses (HERVs) and other repetitive elements in psoriatic skin.

Human endogenous retrovirus (HERV) sequences make up at least 8% of the human genome. Transcripts originating from these loci as well as proteins encoded by them have been detected in various tissues. HERVs are believed to be implicated in autoimmune diseases, however the extent to which, has remained unclear. Differential expression studies have so far been limited to certain HERV subfamilies with conserved sequences. No studies have been published describing the genome-wide expression pattern of HERVs and repetitive elements in the context of psoriasis. In the present study, we analysed total RNA sequencing data from skin samples of 12 psoriasis patients and 12 healthy controls, which enabled us to describe the entire transcriptional landscape of repetitive elements. We report high levels of repetitive element expression in the skin of psoriasis patients as well as healthy controls. The majority of differentially expressed elements were downregulated in lesional and non-lesional skin, suggesting active HERV suppression in the pro-inflammatory environment of psoriatic skin. However, we also report upregulation of a small subset of HERVs previously described in the context of autoimmune diseases, such as members of the HERV-K and W families, with the potential to affect the immunopathogenesis of psoriasis.

Correction: Melanocytes in the Skin - Comparative Whole Transcriptome Analysis of Main Skin Cell Types.

[This corrects the article DOI: 10.1371/journal.pone.0115717.].

Psoriasis-Specific RNA Isoforms Identified by RNA-Seq Analysis of 173,446 Transcripts.

BACKGROUND: Several studies have been published that investigated potential links between transcriptome changes and psoriasis using microarrays and RNA-seq technologies, but no previous study has analyzed expression profile of alternatively spliced transcripts in psoriasis. OBJECTIVES: Identification of potential alternatively spliced RNA isoforms with disease-specific expression profile. METHODS: Using our published RNA sequencing data from lesional psoriatic (LP), non-lesional psoriatic (NLP), and normal control skin (C), we analyzed the differential expression of RNA splicing variants. LP sample was compared with NLP, as was LP with C and NLP with C. RESULTS: Transcript-based annotation analyzed 173,446 transcripts (RNA isoforms), and around 9,000 transcripts were identified as differentially expressed between study groups. Several previously undescribed RNA variants were found. For instance, transcript ETV3_3 (ENST00000326786) was significantly downregulated in LP and NLP skin. ETV3 is a transcriptional repressor that contributes to the downstream anti-inflammatory effects of IL-10. We also identified diseases-specific transcripts (S100A7A, IL36RN_4, and IL36G_3) of genes already recognized to be involved in inflammation and immune response. CONCLUSION: Psoriasis is characterized by significant differences in the expression of RNA alternative isoforms. Description of these new isoforms improves our knowledge about this complex disease.

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.

Melanocytes in the skin--comparative whole transcriptome analysis of main skin cell types.

Melanocytes possess several functions besides a role in pigment synthesis, but detailed characteristics of the cells are still unclear. We used whole transcriptome sequencing (RNA-Seq) to assess differential gene expression of cultivated normal human melanocytes with respect to keratinocytes, fibroblasts and whole skin. The present results reveal cultivated melanocytes as highly proliferative cells with possible stem cell-like properties. The enhanced readiness to regenerate makes melanocytes the most vulnerable cells in the skin and explains their high risk of developing into malignant melanoma.

Expression of class II cytokine genes in children's skin.

Immune regulation of the skin plays an important role in susceptibility and development of illnesses. The aim of our study was to localise the interleukin (IL)-10 family of cytokines, in children's skin and to determine possible age-related differences in the expression level. The mRNA expression level of IL10, IL19, IL20, IL22, IL24, IL26, IL28B, IL29 and their receptors IL10RA, IL10RB, IL20RA, IL20RB, IL22RA1, IL22RA2, IL28RA was compared in skin biopsies of children and adults and in childrens' skin cells by quantitative real-time PCR (qRT-PCR). Immunohistochemistry was performed to confirm the qRT-PCR findings. We found age-related differences in the expression of IL10RB, IL20, IL20RA, IL22RA1, IL22RA2, IL26 and IL28RA genes. Cell type-dependent expression of IL10 family cytokines was apparent in the skin. In addition to previously known differences in systemic immunological response of adults and children, the present results reveal differences in immune profile of adult and juvenile skin.

Copy number variations in IL22 gene are associated with Psoriasis vulgaris.

Psoriasis vulgaris (PsV) is a frequent, chronically relapsing, immune-mediated systemic disease with characteristic skin changes. IL22 is a cytokine of IL10 family, with significant proliferative effect on different cell lines. Copy number variations (CNV) have been discovered to have phenotypic consequences and are associated with various types of diseases. In the work presented here we analyzed the copy number variations in IL22 gene of exon1 and exon5. Our results showed that the IL22 gene exon1 was significantly associated with psoriasis severity (P<0.0001). However, the association between IL22 gene exon5 copy numbers and psoriasis was not detected.

Quality of life and emotional state in vitiligo in an Estonian sample: comparison with psoriasis and healthy controls.

The impact of vitiligo on quality of life is controversial. The aim of this study was to observe the impairment of quality of life and emotional state in adults with vitiligo compared with subjects with psoriasis and unaffected controls. The study group comprised 54 subjects with vitiligo, 57 with psoriasis and 57 unaffected controls. All subjects were examined and interviewed using the Dermatology Life Quality Index (DLQI) and Emotional State questionnaires. The total mean DLQI score in vitiligo was 4.7, compared with 0.6 in healthy controls (p<0.001) and 13.1 in psoriasis (p<0.001). In vitiligo, females experienced a greater impact on feelings and men experienced a greater impact on relationships. Lower quality of life in vitiligo was associated with active stage of the disease, extension of pigment loss, depigmentation on the hands, and earlier onset of disease. The results demonstrate that vitiligo has less impact on quality of life than psoriasis.

Gene expression analysis of the corticotrophin-releasing hormone-proopiomelanocortin system in psoriasis skin biopsies.

The corticotrophin-releasing hormone-proopiomelanocortin (CRH-POMC) system in the skin coordinates pigmentation and the immune response. The aim of this study was to evaluate the regulatory role of the neuroendocrine system in the pathogenesis of psoriasis. Using quantitative real-time-PCR, mRNA expression levels of 15 genes related to the CRH-POMC system were measured in punch biopsies from lesional and non-lesional skin of patients with psoriasis and from skin of healthy control subjects. Statistically significant up-regulation of POMC, CRH receptor type 1, melanin-concentrating hormone receptor (MCHR1) and melanocortin receptors 2, 3 and 4 mRNA expression in lesional and in non-lesional skin compared with healthy control samples were established. Tyrosinase (TYR), T(Y)RP-1 and ASIP genes were statistically significantly down-regulated in lesional and non-lesional skin of psoriasis samples compared with healthy subjects. The up-regulation of POMC, melanocortin receptors, CRH receptor type 1 and MCHR1 in the lesional and non-lesional skin of psoriasis patients supports the importance of the local CRH-POMC system in the pathogenesis of psoriasis.

Expression profile of genes associated with the dopamine pathway in vitiligo skin biopsies and blood sera.

BACKGROUND: Dopamine has been proven to be toxic for melanocytes. In vitiligo patients the level of dopamine is increased and the functioning of several enzymes participating in the dopamine pathway is changed. METHODS: With the use of quantitative real-time polymerase chain reaction and ELISA the expression of genes connected to the dopamine pathway (PAH, PCD, TH, DDC, DBH, PNMT, GPX1, MAOA, MAOB, COMT, DRD1-DRD5, VMAT1 and VMAT2) was observed in vitiligo patients' and control subjects' skin and blood. RESULTS: The mRNA expression of GPX1, DDC, MAOA, DRD1 and DRD5 differs in vitiligo skin and the protein level of DDC, MAOA, MAOB, DRD1 and DRD5 is changed in vitiligo patients' skin and/or blood sera. CONCLUSIONS: The dopamine pathway probably influences melanogenesis directly or through the melanocortin pathway. We provide new data about changes of expression profile of the dopamine-synthesizing enzyme DDC, the dopamine-degrading enzymes MAOA and MAOB and the D1-like family dopamine receptors in vitiligo skin and blood sera.

The mRNA expression profile of cytokines connected to the regulation of melanocyte functioning in vitiligo skin biopsy samples and peripheral blood mononuclear cells.

The expression pattern of several genes associated with different processes in melanocytes, including melanogenesis, is changed in vitiligo patients. We evaluated possible changes in the expression of interleukin (IL)-10 family cytokines (IL26, IL-28A, IL28B, IL29), their receptor subunits (IL20RB, IL22RA2, IL28RA), and genes potentially related to functioning of melanocytes (MDM1, IFNA1, IFNB1, IFNG, and ICAM1) in the case of vitiligo. We observed mRNA expression in vitiligo patients' and controls' skin and peripheral blood mononuclear cells using quantitative real-time polymerase chain reaction. The mRNA expression pattern of IL20RB, IL22RA2, IL-28A, IL28B, IL28RA, MDM1, IFNA1, IFNB1, IFNG, and ICAM1 changed in vitiligo skin and/or peripheral blood mononuclear cells (PBMC) compared with controls. All of these genes may potentially be involved in vitiligo pathogenesis through controlling or participating in different pathways that regulate survival/apoptosis, development and migration of melanocytes, and melanogenesis. This study presents additional support for our previous findings about the importance of IL-10 family cytokines in vitiligo, in particular the possible involvement of IL-22. Further studies should be considered.

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.