IL-6 Up-Regulates Expression of LIM-Domain Only Protein 4 in Psoriatic Keratinocytes through Activation of the MEK/ERK/NF-κB Pathway.

Psoriasis is a chronic inflammatory skin disease characterized by the activation of keratinocytes and the infiltration of immune cells. Overexpression of the transcription factor LIM-domain only protein 4 (LMO4) promoted by IL-23 has critical roles in regulating the proliferation and differentiation of psoriatic keratinocytes. IL-6, an autocrine cytokine in psoriatic epidermis, is a key mediator of IL-23/T helper 17-driven cutaneous inflammation. However, little is known about how IL-6 regulates the up-regulation of LMO4 expression in psoriatic lesions. In this study, human immortalized keratinocyte cells, clinical biopsy specimens, and an animal model of psoriasis induced by imiquimod cream were used to investigate the role of IL-6 in the regulation of keratinocyte proliferation and differentiation. Psoriatic epidermis showed abnormal expression of IL-6 and LMO4. IL-6 up-regulated the expression of LMO4 and promoted keratinocyte proliferation and differentiation. Furthermore, in vitro and in vivo studies showed that IL-6 up-regulates LMO4 expression by activating the mitogen-activated extracellular signal-regulated kinase (MEK)/extracellular signal-regulated kinase (ERK)/NF-κB signaling pathway. These results suggest that IL-6 can activate the NF-κB signaling pathway, up-regulate the expression of LMO4, lead to abnormal proliferation and differentiation of keratinocytes, and promote the occurrence and development of psoriasis.

Single-cell technologies in psoriasis.

Psoriasis is a chronic and recurrent inflammatory skin disorder. The primary manifestation of psoriasis arises from disturbances in the cutaneous immune microenvironment, but the specific functions of the cellular components within this microenvironment remain unknown. Recent advancements in single-cell technologies have enabled the detection of multi-omics at the level of individual cells, including single-cell transcriptome, proteome, and metabolome, which have been successfully applied in studying autoimmune diseases, and other pathologies. These techniques allow the identification of heterogeneous cell clusters and their varying contributions to disease development. Considering the immunological traits of psoriasis, an in-depth exploration of immune cells and their interactions with cutaneous parenchymal cells can markedly advance our comprehension of the mechanisms underlying the onset and recurrence of psoriasis. In this comprehensive review, we present an overview of recent applications of single-cell technologies in psoriasis, aiming to improve our understanding of the underlying mechanisms of this disorder.

Relief of Residual Stress in Bulk Thermosets in the Glassy State by Local Bond Exchange.

The covalently cross-linked network gives thermosets superior thermal, mechanical, and electrical properties, which, however, squarely makes the large residual stress that is inevitably induced during preparation hardly relieved in the glassy state. In this work, an incredible reduction in residual stress is successfully achieved in bulk thermosets in the glassy state through introducing highly dynamic thiocarbamate bonds by "click" reactions of thiols and isocyanates. Due to the excellent dynamic behaviors of thiocarbamate bonds, local network rearrangement is achieved through thermal stimulation, while the strong 3D cross-linked network is well maintained. Ultimately, a decrease by 44% in residual stress is detected by simply annealing samples at 30 °C below glass transition temperature (Tg), during which they could well maintain more than 98.4% of the storage modulus. After the annealing, more uniform residual stress distribution is also observed, showing a 32% decline in sample standard deviation. However, the residual stress of epoxy resin, a typical thermoset as a reference, changes little even after annealing at Tg. The results prove it a feasible strategy to reduce residual stress in bulk thermosets in the glassy state by introducing proper dynamic covalent bonds.

Metabolomic Alterations in Methotrexate Treatment of Moderate-to-Severe Psoriasis.

BACKGROUND Aberrant lipid metabolism alterations in skin tissue, blood, or urine have been implicated in psoriasis. Here, we examined lipid metabolites related to psoriasis and their association with the age of disease onset. MATERIAL AND METHODS Differences in lipid metabolites before and after methotrexate (MTX) treatment were evaluated. The discovery cohort and validation cohort consisted of 50 and 46 patients, respectively, with moderate-to-severe psoriasis. After MTX treatment, the patients were divided into response (Psoriasis Area and Severity Index [PASI] 75 and above) and non-response (PASI below 75) groups, blood was collected for serum metabolomics, and multivariate statistical analysis was performed. RESULTS We detected 1546 lipid metabolites. The proportion of the top 3 metabolites was as follows: triglycerides (TG, 34.8%), phospholipids (PE, 14.5%), phosphatidylcholine (PC, 12.4%); diglycerides (DG) (16: 1/18: 1), and DG (18: 1/18: 1) showed strong positive correlations with onset age. There were marked changes in TG (16: 0/18: 0/20: 0), TG (18: 0/18: 0/22: 0), TG (14: 0/18: 0/22: 0), TG (14: 0/20: 0/20: 0), lysophosphatidylcholine (LPC) (16: 0/0: 0), LPC (18: 0/0: 0), LPC (14: 0/0: 0), and LPC (18: 1/0: 0) levels before and after 12 weeks of MTX treatment. The glycerophospholipid metabolic pathway was implicated in psoriasis development. Of the 96 recruited patients, 35% were MTX responders and 65% non-responders. PE (34: 4) and PE (38: 1) levels were significantly different between the groups. Obvious differences in lipid metabolism were found between early-onset (<40 years) and late-onset (≥40 years) psoriasis. Significant changes in serum lipid profile before and after MTX treatment were observed. CONCLUSIONS The specific lipid level changes in responders may serve as an index for MTX treatment efficacy evaluation.

Development and validation of a sensitive UPLC-MS/MS analytical method for GFH009 in rat plasma and its application to toxicokinetics studies.

GFH009 is a potent, highly selective, small molecule that targets and inhibits the activity of the CDK9/cyclin T1 regulatory complex of P-TEFb. This study aimed to develop and validate a highly selective and sensitive ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for precise quantification of GFH009 in rat plasma. This method was subsequently employed for conducting toxicokinetic studies of GFH009 in rats. Plasma was prepared using a simple protein precipitation method by acetonitrile. Chromatographic separation of the analytes was achieved on a BEH C18 analytical column with a rapid 3.0 min run time and a flow rate of 0.5 ml/min. The calibration curves for plasma samples exhibited excellent linearity over a wide concentration range of 1.0-1,000 ng/ml for GFH009. Intra- and inter-day accuracies were within 92.7-105.7%, and precisions were no more than 6.7%. Furthermore, the analyte demonstrated stability under four different storage conditions, with variations of <15.0%. This study pioneers a methodological innovation by introducing a highly reliable, specific and sensitive analytical method for GFH009 in rat plasma. The successful application of this method in toxicokinetic studies further underscores its significance, offering valuable insights for the methodology of clinical pharmacokinetic research.

Copy Number Variation Analysis of IL22 and LCE3C in Different Subtypes of Psoriasis in a Chinese Han Population.

BACKGROUND Psoriasis is a chronic, immune-mediated and hyperproliferative skin disease with both genetic and environmental components. Copy number variations (CNV) of IL22 and LCE3C-LCE3B deletion have been confirmed to be predisposed to psoriasis vulgaris (PsV) in several ethnic groups. However, it remains to be clarified whether CNVs of IL22 and LCE3C are associated with different subtypes of psoriasis (psoriatic arthritis, PsA; erythrodermic psoriasis, EP; and generalized pustular psoriasis, GPP). MATERIAL AND METHODS We enrolled 897 Han Chinese individuals, including 478 patients and 419 healthy controls, and detected CNVs of IL22 and LCE3C using the comparative CT method by real-time PCR, and Pearson's χ² test was used to evaluated the copy number difference among subtypes. RESULTS CNVs of IL22 were significantly higher in PsV than in healthy controls (P<0.001). CNV of LCE3C in PsV, PsA, and GPP groups were significantly lower compared to healthy controls. When linked with clinical parameters, mild psoriasis carried less IL22 copy numbers than that in severe psoriasis (P=0.043). Neither IL22 or LCE3C CNVs were associated with age of onset. CONCLUSIONS CNVs of LCE3C and IL22 might differentially contribute to subtypes of psoriasis. These findings suggest complex and diverse genetic variations in and among different clinical subtypes of psoriasis.

Mutational analysis of epidermal and hyperproliferative type I keratins in mild and moderate psoriasis vulgaris patients: a possible role in the pathogenesis of psoriasis along with disease severity.

BACKGROUND: Mutations in keratin proteins have been vastly associated with a wide array of genodermatoses; however, mutations of keratins in psoriasis have not been fully investigated. The main aim of the current research was to identify the mutation in K14, K10, K16, and K17 genes in two stages of psoriasis patients. METHODS: Ninety-six psoriatic skin biopsies were collected. mRNA transcript of K14, K10, K16, and K17 was prepared, amplified, and sequenced. Sanger sequences of all keratins were further validated for mutational analysis using Mutation Surveyor and Alamut Visual. Then, in silico analysis of protein stability and protein and gene expression of all keratins was performed and validated. RESULTS: Out of 44 mutations, about 75% of keratins are highly pathogenic and deleterious. Remaining 25% mutations are less pathogenic and tolerated in nature. In these 33 deleterious mutations were immensely found to decrease keratin protein stability. We also found a correlation between keratin and Psoriasis Area and Severity Index score which added that alteration in keratin gene in skin causes severity of psoriasis. CONCLUSIONS: We strongly concluded that acanthosis and abnormal terminal differentiation was mainly due to the mutation in epidermal keratins. In turn, disease severity and relapsing of psoriasis are mainly due to the mutation of hyperproliferative keratins. These novel keratin mutations in psoriatic epidermis might be one of the causative factors for psoriasis.

Bach2 regulates aberrant activation of B cell in systemic lupus erythematosus and can be negatively regulated by BCR-ABL/PI3K.

OBJECTIVE: This study was aimed to explore the effect of Bach2 on B cells in systemic lupus erythematosus (SLE), as well as the underlying mechanisms. METHODS: Expression of Bach2, phosphorylated-Bach2 (p-Bach2), Akt, p-Akt and BCR-ABL (p210) in B cells isolated from SLE patients and the healthy persons were assessed by Western blot. Immunofluorescence staining was performed to assess the localization of Bach2 in B cells. Enzyme-linked immunosorbent assay (ELISA) was employed to detect IgG produced by B cells. Cell counting kit-8 (CCK-8) and Annexin-V FITC/PI double staining assay were adopted to evaluate cell proliferation and apoptosis in B cells, respectively. RESULTS: Compared to the healthy controls, Bach2, p-Akt and p210 were significantly decreased, while nuclear translocation of Bach2, IgG, CD40 and CD86 obviously up-regulated in B cells from SLE patients. Bach2 significantly inhibited the proliferation, promoted apoptosis of B cells from SLE patients, whereas BCR-ABL dramatically reversed cell changes induced by Bach2. Besides, BCR-ABL also inhibited nuclear translocation of Bach2 in B cells from SLE patients. Further, LY294002 treatment had no effect on decreased expression of Bach2 induced by BCR-ABL, but significantly eliminated BCR-ABL-induced phosphorylation of Bach2 and restored reduced nuclear translocation of Bach2 induced by BCR-ABL in B cells from SLE. CONCLUSIONS: Bach2 may play a suppressive role in B cells from SLE, and BCR-ABL may inhibit the nuclear translocation of Bach2 via serine phosphorylation through the PI3K pathway.

Increased expression of PRKCB mRNA in peripheral blood mononuclear cells from patients with systemic lupus erythematosus.

The polymorphism of PRKCB has been proven to be associated with systemic lupus erythematosus (SLE) in our previous study. We aimed to investigate the relationship between expression of PRKCB mRNA and the Disease Activity Index (SLEDAI) and manifestations of SLE. Quantitative reverse transcription polymerase chain reaction (RT-PCR) was applied to examine the expression of PRKCB mRNA in peripheral blood mononuclear cells of 60 patients with SLE and 62 controls. The Sequenom MassArray System was used to detect genotype SNP rs16972959. The expression levels of PRKCB mRNA in SLE cases were significantly increased compared with those in healthy controls (P < 0.001). In addition, PRKCB mRNA expression levels were negatively correlated with the SLEDAI (P < 0.05, r = -0.322), with lower mRNA expression levels of PRKCB in patients found with higher SLEDAI, presence of a new rash (P < 0.01), and proteinuria (P < 0.05). No association evidence was observed between the genotype of the variant rs16972959 and PRKCB mRNA expression levels; however, SNP rs16972959 was found to be an expression quantitative trait loci for PRKCB with the SLE risk allele correlated with increased expression in naïve monocytes (PFDR  = 9.12 × 10-13 ) and stimulated monocytes (9.24 × 10-6  > PFDR  > 2.75 × 10-17 ). On the other hand, SNP rs16972959 of PRKCB was found to have suggestive significant associations with vasculitis (P = 0.00718) of SLE. These results indicated that expression of PRKCB mRNA may be correlated with the pathogenesis of SLE; however, more investigation is still needed.

Exome-wide association study identifies four novel loci for systemic lupus erythematosus in Han Chinese population.

OBJECTIVES: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease of considerable genetic predisposition. Genome-wide association studies have identified tens of common variants for SLE. However, the majority of them reside in non-coding sequences. The contributions of coding variants have not yet been systematically evaluated. METHODS: We performed a large-scale exome-wide study in 5004 SLE cases and 8179 healthy controls in a Han Chinese population using a custom exome array, and then genotyped 32 variants with suggestive evidence in an independent cohort of 13 246 samples. We further explored the regulatory effect of one novel non-coding single nucleotide polymorphism (SNP) in ex vivo experiments. RESULTS: We discovered four novel SLE gene regions (LCT, TPCN2, AHNAK2 and TNFRSF13B) encompassing three novel missense variants (XP_016859577.1:p.Asn1639Ser, XP_016859577.1:p.Val219Phe and XP_005267356.1:p.Thr4664Ala) and two non-coding variants (rs10750836 and rs4792801) with genome-wide significance (pmeta <5.00×10-8). These variants are enriched in several chromatin states of primary B cells. The novel intergenic variant rs10750836 exhibited an expression quantitative trait locus effect on the TPCN2 gene in immune cells. Clones containing this novel SNP exhibited gene promoter activity for TPCN2 (P=1.38×10-3) whose expression level was reduced significantly in patients with SLE (P<2.53×10-2) and was suggested to be further modulated by rs10750836 in CD19+ B cells (P=7.57×10-5) in ex vivo experiments. CONCLUSIONS: This study identified three novel coding variants and four new susceptibility gene regions for SLE. The results provide insights into the biological mechanism of SLE.

NFKB1 mediates Th1/Th17 activation in the pathogenesis of psoriasis.

This study was aimed to investigate whether NFKB1 participates in the pathogenesis of psoriasis by mediating Th1/Th17 cells. In this study, expression of NFKB1 was assessed in skin tissues from psoriasis patients and the healthy controls through Western blot and Immunohistochemistry. Enzyme-linked immunosorbent assay (ELISA) was used to analyze the serum levels of IFN-γ, IL-17 (IL-17A) and IL-17RA. The imiquimod-induced psoriasis mouse model was employed to examine the role of NFKB1 in psoriasis via the assessment of psoriasis area and severity index (PASI), including erythema, thickness and scales. The effects of NFKB1 on Th1/Th17 cells in were examined by flow cytometry. In vitro co-culture of Th1/Th17 cells isolated from different mice with HaCat cells was conducted to elucidate the effect of Th1/Th17 cells-mediated by NFKB1 on HaCat cells by MTT, wound healing and transwell invasion assay, respectively. The results showed that NF-κB p105/p50 expression in skin tissues was significantly increased in psoriasis (n = 21) compared to the healthy controls (n = 16), as well as levels of serum INF-γ and IL-17. Additionally, NF-κB p105/p50 expression in lesional skin tissues was much higher than that in non-lesional skin tissues of the same patients. In the psoriasis mouse model, NFKB1 overexpression significantly elevated the scores of erythema, thickness and scales. Besides, NFKB1 up-regulated the level of NF-κB p105/p50, INF-γ, T-bet, IL-17 and RORγt, as well as Th1/Th17 cells in skin tissues of psoriasis mice. Finally, in vitro assay confirmed that the activation of Th1 and Th17 mediated by NFKB1 in psoriasis promoted the proliferation, migration and invasion of keratinocytes. These findings suggest a critical role for NFKB1 in the regulation of Th1 and Th17 in psoriasis.

Major Histocompatibility Complex and Psoriasis.

Major histocompatibility complex (MHC), also known as human leukocyte antigen (HLA) in humans, is one of the most genetically diverse regions in the genome of various species. The human MHC contains about 400 genes in a ∼7.6-Mb span located on the short arm of the chromosomal region 6p21.3. According to the NHGRI-EBI Catalog of published genome-wide association studies (http://www.ebi.ac.uk/gwas/) in HLA region, more than 500 associations have been identified for about 200 traits or phenotypes, including primary immune deficiencies, autoimmune diseases, susceptibility to infections, malignancies, and psychiatric conditions (Welter et al., 2014). For example, multiple sclerosis is associated with HLA-DRB1∗1501 (Handunnetthi et al., 2010); the control of HIV viral load is associated with variants near HLA-C (Kulpa and Collins, 2011). Some acute drug reactions are associated with specific HLA alleles. Carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis have been strongly associated with HLA-B*1502 in Han Chinese population and HLA-A*3101 in European populations (Chung et al., 2004; McCormack et al., 2011). The HLA-B*13:01 is associated with the development of the dapsone hypersensitivity syndrome among patients with leprosy (Zhang et al., 2013).

Discovery of N-aryl-N'-pyrimidin-4-yl ureas as irreversible L858R/T790M mutant selective epidermal growth factor receptor inhibitors.

A novel series of N-aryl-N'-pyrimidin-4-yl ureas has been optimized to afford potent and selective inhibitors of the EGFR L858R/T790M. The most representative compound 28 showed high activity against EGFR L858R/T790M kinase (IC50 = 4 nM) and 22-fold selectivity against wild type EGFR. Moreover, compound 28 potently inhibited EGFR L858R/T790M phosphorylation (IC50 = 41 nM) and cellular proliferation (IC50 = 37 nM) in the H1975 cell line, while being significantly less toxic to A431 cells. Further, compound 28 exhibited a great selectivity in a mini-panel of kinases.

Genetic factors are stressed variably by onset age-based sample selection in psoriasis: A hint from major histocompatibility complex region-based analysis.

BACKGROUND: Large cohort-based genetic association studies have been established over a decade. However, for certain diseases, different results with respect to the genome-wide association study level have been obtained among studies, even for those conducted within the same ethnic groups. We hypothesized that onset age-based sample variables might have a great impact on the results. METHODS: In the present study, we divided psoriasis patients into several subgroups according to the onset age bracket. We conducted genetic association analysis in the major histocompatibility complex (MHC) region of each patient subgroup with shared control subjects. RESULTS: We found decreases in the numbers of susceptible variants in each subgroup analysis as the onset age increased in the longitudinal analysis. Meanwhile, the pairwise analysis showed that younger patients exhibited greater numbers of genetic risks in the MHC region compared to elder patients, regardless of whether the cut-off values were defined as 20 or 30 years old. Similar results were also found among 11-20-, 21-30- and 31-40-year-old groups. Furthermore, when combining the results of both the stepwise regression analysis and the HLA-C*06:02 conditioning analysis, different variants were found to be independently associated with each psoriasis subgroup. CONCLUSIONS: Onset age-based sample variables influence the results of genetic association studies, at least in MHC region-based genetic analysis. We suggest that caution is required when selecting samples for genetic association studies to prevent confounders that might be a result of onset age.

Association analyses identify two susceptibility loci 5q31 and 5q22.1 for atopic dermatitis in Chinese Han population.

BACKGROUND: Atopic dermatitis (AD) and other atopic diseases often share some common genetic and pathogenic bases. Recent genome-wide association studies (GWAS) have identified several loci associated with atopic diseases, allergic sensitization and asthma in different populations. The aim of this study was to investigate whether these susceptibility loci were related to AD in Chinese Han population. METHODS: Eight single nucleotide polymorphisms (SNPs) from recent atopic diseases and allergic sensitization GWAS were genotyped in 3,013 AD patients and 5,483 healthy controls in Chinese Han population using Sequenom MassArray system. Data was analyzed with PLINK 1.07 software. RESULTS: We identified that the susceptibility loci at 5q31 (RAD50/IL13, rs2158177, P = 1.08×10-3, OR = 1.15) and 5q22.1 (TSLP, rs1837253, P = 2.66×10-3, OR = 0.91) were significantly associated with AD. Genotype-based association testing revealed that the dominant model provided the best fit for both rs2158177 (P = 3.75×10-3) and rs1837253 (P = 5.30×10-3). Pathway analysis conformed that both loci were associated with the JAK-STAT signaling pathway. CONCLUSIONS: We identified two susceptibility loci 5q31 and 5q22.1 for AD that might bear candidate genes conferring susceptibility to AD.

A Genetic Variant rs1020760at NFKB1 is Associated with Clinical Features of Psoriasis Vulgaris in a Han Chinese Population.

Psoriasis vulgaris is a chronic inflammatory skin disease associated with complex genetic susceptibility. Recently, we identified a single-nucleotide variant rs1020760 at NFKB1 significantly associated with psoriasis in a Han Chinese population in deep analysis of exome and targeted sequencing (P = 1.76 × 10(-8) ). To investigate the potential association between rs1020760 and phenotypes of psoriasis vulgaris, we performed a genotype-phenotype analysis. A total of 9946 cases and 9906 controls with detailed clinical and demographic information were involved in this study, while the genotype data of rs1020760 was available in the previous targeted sequencing study of psoriasis. Genotype-based association testing revealed the additive model might provide the best fit for rs1020760 (P = 5.44 × 10(-8) ). Case-only analysis showed that the distribution of allele G was significantly different between the cases with and without family history (Pallele = 4.07 × 10(-3) ,Pgenotype = 5.75 × 10(-3) ). The differences in allele and genotype frequencies were observed between all the subphenotypes and controls except for the genotype frequency of the late onset subgroup, while no difference was found in case-only analysis for the other two subphenotypes. Rs1020760 was preferentially associated with family history of psoriasis, implying that NFKB1 might not only play important roles in the development of psoriasis, but might also contribute to the special phenotypes of this disease.

Meta-analysis followed by replication identifies loci in or near CDKN1B, TET3, CD80, DRAM1, and ARID5B as associated with systemic lupus erythematosus in Asians.

Systemic lupus erythematosus (SLE) is a prototype autoimmune disease with a strong genetic involvement and ethnic differences. Susceptibility genes identified so far only explain a small portion of the genetic heritability of SLE, suggesting that many more loci are yet to be uncovered for this disease. In this study, we performed a meta-analysis of genome-wide association studies on SLE in Chinese Han populations and followed up the findings by replication in four additional Asian cohorts with a total of 5,365 cases and 10,054 corresponding controls. We identified genetic variants in or near CDKN1B, TET3, CD80, DRAM1, and ARID5B as associated with the disease. These findings point to potential roles of cell-cycle regulation, autophagy, and DNA demethylation in SLE pathogenesis. For the region involving TET3 and that involving CDKN1B, multiple independent SNPs were identified, highlighting a phenomenon that might partially explain the missing heritability of complex diseases.

Common susceptibility variants are shared between schizophrenia and psoriasis in the Han Chinese population.

BACKGROUND: Previous studies have shown that individuals with schizophrenia have a greater risk for psoriasis than a typical person. This suggests that there might be a shared genetic etiology between the 2 conditions. We aimed to characterize the potential shared genetic susceptibility between schizophrenia and psoriasis using genome-wide marker genotype data. METHODS: We obtained genetic data on individuals with psoriasis, schizophrenia and control individuals. We applied a marker-based coheritability estimation procedure, polygenic score analysis, a gene set enrichment test and a least absolute shrinkage and selection operator regression model to estimate the potential shared genetic etiology between the 2 diseases. We validated the results in independent schizophrenia and psoriasis cohorts from Singapore. RESULTS: We included 1139 individuals with psoriasis, 744 with schizophrenia and 1678 controls in our analysis, and we validated the results in independent cohorts, including 441 individuals with psoriasis (and 2420 controls) and 1630 with schizophrenia (and 1860 controls). We estimated that a large fraction of schizophrenia and psoriasis risk could be attributed to common variants (h2SNP = 29% ± 5.0%, p = 2.00 × 10-8), with a coheritability estimate between the traits of 21%. We identified 5 variants within the human leukocyte antigen (HLA) gene region, which were most likely to be associated with both diseases and collectively conferred a significant risk effect (odds ratio of highest risk quartile = 6.03, p < 2.00 × 10-16). We discovered that variants contributing most to the shared heritable component between psoriasis and schizophrenia were enriched in antigen processing and cell endoplasmic reticulum. LIMITATIONS: Our sample size was relatively small. The findings of 5 HLA gene variants were complicated by the complex structure in the HLA region. CONCLUSION: We found evidence for a shared genetic etiology between schizophrenia and psoriasis. The mechanism for this shared genetic basis likely involves immune and calcium signalling pathways.