Genetic risk and protective factors of TNFSF15 gene variants detected using single nucleotide polymorphisms in Hungarians with psoriasis and psoriatic arthritis

Targeting TL1A and DR3: the new frontier of anti-cytokine therapy in IBD

TNF-like cytokine 1A (TL1A) and its functional receptor, death-domain receptor 3 (DR3), are members of the TNF and TNFR superfamilies, respectively, with recognised roles in regulating innate and adaptive immune responses; additional existence of a decoy receptor, DcR3, indicates a tightly regulated cytokine system. The significance of TL1A:DR3 signalling in the pathogenesis of inflammatory bowel disease (IBD) is supported by several converging lines of evidence. Herein, we aim to provide a comprehensive understanding of what is currently known regarding the TL1A/DR3 system in the context of IBD. TL1A and DR3 are expressed by cellular subsets with important roles for the initiation and maintenance of intestinal inflammation, serving as potent universal costimulators of effector immune responses, indicating their participation in the pathogenesis of IBD. Recent evidence also supports a homoeostatic role for TL1A:DR3 via regulation of Tregs and innate lymphoid cells. TL1A and DR3 are also expressed by stromal cells and may contribute to inflammation-induced or inflammation-independent intestinal fibrogenesis. Finally, discovery of genetic polymorphisms with functional consequences may allow for patient stratification, including differential responses to TL1A-targeted therapeutics. In conclusion, TL1A:DR3 signalling plays a central and multifaceted role in the immunological pathways that underlie intestinal inflammation, such as that observed in IBD. Such evidence provides the foundation for developing pharmaceutical approaches targeting this ligand-receptor pair in IBD.

Roles of tumor necrosis factor-like ligand 1A in γδT-cell activation and psoriasis pathogenesis

Background

Interleukin (IL)-17-producing γδT (γδT17) cells mediate inflammatory responses in barrier tissues. Dysregulated γδT17 cell activation can lead to the overproduction of IL-17 and IL-22 and the development of inflammatory diseases, including psoriasis. IL-23 and IL-1β are known to synergistically activate γδT17 cells, but the regulatory mechanisms of γδT17 cells have not been fully elucidated. This study aimed to reveal the contribution of the inflammatory cytokine tumor necrosis factor-like ligand 1A (TL1A) to γδT17 cell activation and psoriasis development.

Methods

Anti-TL1A antibody was injected into an imiquimod (IMQ)-induced murine psoriasis model. TL1A receptor expression was analyzed in splenic and dermal γδT cells. γδT cells were tested for cytokine production in vitro and in vivo under stimulation with IL-23, IL-1β, and TL1A. TL1A was applied to a psoriasis model induced by intradermal IL-23 injection. Mice deficient in γδT cells were intradermally injected with IL-23 plus TL1A to verify the contribution of TL1A-dependent γδT-cell activation to psoriasis development.

Results

Neutralization of TL1A attenuated γδT17 cell activation in IMQ-treated skin. TL1A induced cytokine production by splenic γδT17 cells in synergy with IL-23. Dermal γδT17 cells constitutively expressed a TL1A receptor at high levels and vigorously produced IL-22 upon intradermal IL-23 and TL1A injection but not IL-23 alone. TL1A exacerbated the dermal symptoms induced by IL-23 injection in wild-type but not in γδT cell-deficient mice.

Conclusion

These findings suggest a novel regulatory mechanism of γδT cells through TL1A and its involvement in psoriasis pathogenesis as a possible therapeutic target.

Role of TL1A in Inflammatory Autoimmune Diseases: A Comprehensive Review

TL1A, also called TNFSF15, is a member of tumor necrosis factor family. It is expressed in different immune cell, such as monocyte, macrophage, dendritic cell, T cell and non-immune cell, for example, synovial fibroblast, endothelial cell. TL1A competitively binds to death receptor 3 or decoy receptor 3, providing stimulatory signal for downstream signaling pathways, and then regulates proliferation, activation, apoptosis of and cytokine, chemokine production in effector cells. Recent findings showed that TL1A was abnormally expressed in autoimmune diseases, including rheumatoid arthritis, inflammatory bowel disease, psoriasis, primary biliary cirrhosis, systemic lupus erythematosus and ankylosing spondylitis. In vivo and in vitro studies further demonstrated that TL1A was involved in development and pathogenesis of these diseases. In this study, we comprehensively discussed the complex immunological function of TL1A and focused on recent findings of the pleiotropic activity conducted by TL1A in inflammatory autoimmune disease. Finish of the study will provide new ideas for developing therapeutic strategies for these diseases by targeting TL1A.

The association of HLA-C and ERAP1 polymorphisms in early and late onset psoriasis and psoriatic arthritis patients of Hungary

Introduction

Single nucleotide polymorphisms (SNPs) of the HLA-C and ERAP1 genes were recently determined to contribute to psoriasis susceptibility. However, data regarding the association of these genes with specific subgroups of psoriasis are scarce.

Aim

To examine the possible association of the HLA-C and ERAP-1 polymorphisms with early and late onset psoriasis and psoriatic arthritis.

Material and methods

Five ERAP1 SNPs and two HLA-C SNPs were genotyped in 105 psoriatic arthritis patients, 214 cutaneous psoriasis patients and 200 healthy individuals. Haplotypes were constructed for three ERAP1 SNPs (rs17482078, rs10050860, rs30187), and interaction between HLA-Cw*0602 and ERAP1 was also analysed.

Results

The HLA-Cw*0602 rs10484554 SNP was found to be a strong susceptibility factor for early onset cutaneous psoriasis and early onset psoriatic arthritis. ERAP1 SNPs (rs10050860, rs17482078, rs27525) appear to have a protective function for early onset psoriatic arthritis. The haplotype B was identified as a susceptibility factor for late onset psoriatic arthritis. In HLA-C positive individuals the rs27524 ERAP1 SNP was associated with a significantly increased risk of psoriatic arthritis development, whereas the rs27525 ERAP1 SNP had the opposite effect.

Conclusions

These results suggest that the HLA-C and ERAP1 genes contribute to the pathogenesis of psoriasis and psoriatic arthritis in an age-dependent manner.

The Role of Co-Signaling Molecules in Psoriasis and Their Implications for Targeted Treatment

Psoriasis is a chronic, systemic immune-mediated inflammatory disease manifesting in the skin, joint or both. Co-signaling molecules are essential for determining the magnitude of the T cell response to the antigen. According to the function of co-signaling molecules, they can be divided into co-stimulatory molecules and co-inhibitory molecules. The role of co-signaling molecules in psoriasis is recognized, mainly including the co-stimulatory molecules CD28, CD40, OX40, CD27, DR3, LFA-1, and LFA-3 and the co-inhibitory molecules CTLA-4, PD-1, and TIM-3. They impact the pathological process of psoriasis by modulating the immune strength of T cells, regulating the production of cytokines or the differentiation of Tregs. In recent years, immunotherapies targeting co-signaling molecules have made significant progress and shown broad application prospects in psoriasis. This review aims to outline the possible role of co-signaling molecules in the pathogenesis of psoriasis and their potential application for the treatment of psoriasis.

Polymorphism rs6478109 in the TNFSF15 gene contributes to the susceptibility to Crohn's disease but not ulcerative colitis: a meta-analysis

Objective

Polymorphisms in the tumor necrosis factor superfamily 15 (TNFSF15) gene contribute to susceptibility to inflammatory bowel disease (IBD). However, associations between TNFSF15 rs6478109, rs7869487, and rs7865494 polymorphisms and IBD remain unclear.

Methods

Eligible articles were retrieved from the PubMed, EMBASE, Web of Science, and CNKI databases through 20 March 2020. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to evaluate the relationships of TNFSF15 polymorphisms with IBD susceptibility.

Results

Under the recessive model, TNFSF15 rs6478109 was associated with IBD risk (OR = 0.56; 95% CI: 0.35, 0.92). Stratification analyses based on the type of disease—Crohn’s disease (CD) or ulcerative colitis (UC)—revealed a significant association under the allelic and recessive models between TNFSF15 rs6478109 and CD (allelic model: OR = 0.84, 95% CI: 0.71, 0.99; recessive model: OR = 0.44, 95% CI: 0.22, 0.87) but not UC. Stratification by ethnicity indicated a significantly decreased risk of IBD in Asian populations with TNFSF15 rs6478109 under the recessive model (OR = 0.56, 95% CI: 0.35, 0.92).

Conclusions

Our meta-analysis suggested that under the allelic and recessive models, the TNFSF15 rs6478109 polymorphism was likely protective for CD but not UC in the Asian population.

Association between TL1A gene polymorphisms and systemic lupus erythematosus in a Chinese Han population

Our previous studies showed elevated tumor necrosis factor-like ligand 1 aberrance (TL1A) expression in systemic lupus erythematosus (SLE). However, TL1A polymorphisms with SLE susceptibility remain to be elucidated. In addition, we made meta-analysis to evaluate the relationship of TL1A polymorphisms and autoimmune diseases owing to inconsistent results. The present research was carried out by 404 SLE, 150 primary Sjogren's syndrome (pSS) patients, and 574 healthy individuals. Three TL1A polymorphisms (rs3810936, rs6478109, rs7848647) were genotyped using TaqMan genotyping assay. Then, the meta-analysis was performed by collecting the present case-control study and previously published research. Results showed that genotypes of rs3810936, rs7848647 were different between SLE patients and healthy controls, whereas no significant association was observed in the three polymorphisms and pSS patients. Genotypes distribution of rs6478109, rs7848647 were strongly related to lupus nephritis within SLE (p = 0.004, p = 0.011), respectively. Moreover, combined meta-analysis consisted of ten comparative research involving 4,305 patients and 5,600 controls. An association between autoimmune diseases and rs6478109 polymorphism was found. Our findings indicate that gene polymorphisms (rs3810936, rs7848647) of TL1A might correlate with lupus.

Association study between two polymorphisms of tumor necrosis factor ligand superfamily member 15 (TNFSF15) gene and ulcerative colitis in south-west of Iran

BACKGROUND AND AIMS: Ulcerative colitis (UC) is the most prevalent clinical manifestation of the inflammatory bowel disease (IBD). Several candidate genes have been suggested to be involved in the genetic susceptibility or resistance in the development of UC. Among them, tumor necrosis factor ligand superfamily member 15 (TNFSF15) have been reported in association with IBD in several studies. The aim of this study was to investigate the association of TNFSF15 gene polymorphisms located in the promoter region, including rs6478108 (G/A -9706) and rs3810936 (G/A -15524) in Iranian patients with UC. METHODS: In this way, the two single nucleotide polymorphisms were studied in 115 patients with UC and 115 healthy controls with the same ethnic group from south-west of Iran. The genomic DNA of samples was genotyped using TaqMan Real-time PCR assay. This case-control study was conducted at the Department of Immunology, Jundishapur University of Medical Sciences, Ahvaz, Iran. RESULTS AND CONCLUSION: Our results did not confirm the formerly reported association of the studied polymorphisms with UC disease in comparison with healthy controls, neither with the type of the clinical forms of Colitis in the studied Iranian population. Comparing the genotype frequency of single nucleotide polymorphism (SNP) rs6478108, wild-type homozygous and heterozygote and mutant homozygote were 33%, 55.7%, and 11.3% in cases vs. 34.8%, 50.4%, and 14.8% in the controls (P = 0.6). The genotype frequency of SNP rs3810936 were 20.9%, 40.9%, and 38.2% in the cases compared to 18.3%, 44.3%, and 37.4% in controls, which was not significant ( P = 0.8). As multiple ethnic groups reside in all around the country, further studies using different ethnicities and/or larger sample size are required to clarify the role of these polymorphisms in the genetic susceptibility of UC in Iranian populations.

TL1A (TNFSF15) and DR3 (TNFRSF25): A Co-stimulatory System of Cytokines With Diverse Functions in Gut Mucosal Immunity

TL1A and its functional receptor DR3 are members of the TNF/TNFR superfamilies of proteins. Binding of APC-derived TL1A to lymphocytic DR3 provides co-stimulatory signals for activated lymphocytes. DR3 signaling affects the proliferative activity of and cytokine production by effector lymphocytes, but also critically influences the development and suppressive function of regulatory T-cells. DR3 was also found to be highly expressed by innate lymphoid cells (ILCS), which respond to stimulation by TL1A. Several recent studies with transgenic and knockout mice as well as neutralizing or agonistic antibodies for these two proteins, have clearly shown that TL1A/DR3 are important mediators of several chronic immunological disorders, including Inflammatory Bowel Disease (IBD). TL1A and DR3 are abundantly localized at inflamed intestinal areas of patients with IBD and mice with experimental ileitis or colitis and actively participate in the immunological pathways that underlie mucosal homeostasis and intestinal inflammation. DR3 signaling has demonstrated a dichotomous role in mucosal immunity. On the one hand, during acute mucosal injury it exerts protective functions by ameliorating the severity of acute inflammatory responses and facilitating tissue repair. On the other hand, it critically participates in the pro-inflammatory pathways that underlie chronic inflammatory responses, such as those that take place in IBD. These effects are mediated through modulation of the relative mucosal abundance and function of Th1, Th2, Th17, Th9, and Treg lymphocytes, but also of all types of ILCs. Recently, an important role was demonstrated for TL1A/DR3 as potential mediators of intestinal fibrosis that is associated with the presence of gut inflammation. These accumulating data have raised the possibility that TL1A/DR3 pathways may represent a valid therapeutic target for chronic immunological diseases. Nevertheless, applicability of such a therapeutic approach will greatly rely on the net result of TL1A/DR3 manipulation on the various cell populations that will be affected by this approach.

Distinct Expression Patterns of Two Tumor Necrosis Factor Superfamily Member 15 Gene Isoforms in Human Colon Cancer

BACKGROUND

Tumor necrosis factor superfamily member 15 (TNFSF15) gene is involved in development of several cancers. It encodes two proteins: tumor necrosis factor ligand-related molecule 1A (TL1A) and vascular endothelial growth inhibitor 192 (VEGI-192). The main receptor for TL1A is death receptor 3 (DR3).

AIMS

We investigated expression of TL1A, VEGI-192, and DR3 transcripts in different stages of colon cancer and compared them with survival of patients. We also aimed to reveal possible effects of microsatellite instability (MSI) and selected TNFSF15 single-nucleotide polymorphisms (SNPs) on expression of this gene.

METHODS

Forty-five healthy individuals and 95 colon cancer patients were included in the study. Expression of VEGI-192, TL1A, and DR3 was measured by quantitative PCR. SNP and MSI analyses were performed on DNA isolated from normal or cancer tissue.

RESULTS

Expression of VEGI-192 and TL1A was elevated in colon cancer, although the level of VEGI-192 decreased, while the level of TL1A increased with the progression of cancer. Patients with low expression of TL1A and/or high expression of VEGI-192 in tumor-transformed tissue showed longer survival. DR3 expression was decreased in the cancer, but it did not change with the tumor progression. Alleles T of rs6478108 and G of rs6478109 SNPs were associated with elevated expression of the TNFSF15 gene. There was no relation between the MSI status and TNFSF15 expression levels.

CONCLUSIONS

Expression of the TNFSF15 gene isoforms was associated with the progression of colon cancer. Levels of TL1A and VEGI-192 transcripts can be considered as independent prognostic factors for colon cancer.

Gene polymorphisms and serum levels of TL1A in patients with rheumatoid arthritis

Recent findings showed elevated expression of tumor necrosis factor (TNF)-like ligand 1A (TL1A) in rheumatoid arthritis (RA) patients and arthritis mice. However, whether TL1A gene polymorphisms may correlate with RA susceptibility needs to be discussed. This case-control study was performed on 350 RA patients and 556 healthy subjects to identify TL1A genetic variants (rs3810936, rs6478109, and rs7848647) and their possible association with TL1A levels, susceptibility to and severity of RA. Odds ratio and 95% confidence interval were calculated to represent the correlation between TL1A polymorphisms and RA. The TL1A serum levels were evaluated. Results showed that frequencies of TC, TT + TC genotypes of rs3810936, rs7848647 in RA patients were significantly lower in RA patients compared with controls. Patients with C allele showed more severe disease course (disease activity index: erythrocyte sedimentation rate, rheumatoid factor) than in carriers of T allele. However, the allele or genotype frequencies of rs6478109 were not associated with RA. In addition, TL1A genetic variants conferred higher TL1A levels in RA patients compared with controls. In conclusion, these findings indicated an association between TL1A rs3810936, rs7848647 variation and the susceptibility of RA in a sample of Chinese individuals, and TL1A may correlate with severity of RA.

Death Receptor 3 Signaling Controls the Balance between Regulatory and Effector Lymphocytes in SAMP1/YitFc Mice with Crohn's Disease-Like Ileitis

Death receptor 3 (DR3), a member of the tumor necrosis factor receptor (TNFR) superfamily, has been implicated in regulating T-helper type-1 (TH1), type-2 (TH2), and type-17 (TH17) responses as well as regulatory T cell (Treg) and innate lymphoid cell (ILC) functions during immune-mediated diseases. However, the role of DR3 in controlling lymphocyte functions in inflammatory bowel disease (IBD) is not fully understood. Recent studies have shown that activation of DR3 signaling modulates Treg expansion suggesting that stimulation of DR3 represents a potential therapeutic target in human inflammatory diseases, including Crohn's disease (CD). In this study, we tested a specific DR3 agonistic antibody (4C12) in SAMP1/YitFc (SAMP) mice with CD-like ileitis. Interestingly, treatment with 4C12 prior to disease manifestation markedly worsened the severity of ileitis in SAMP mice despite an increase in FoxP3+ lymphocytes in mesenteric lymph node (MLN) and small-intestinal lamina propria (LP) cells. Disease exacerbation was dominated by overproduction of both TH1 and TH2 cytokines and associated with expansion of dysfunctional CD25-FoxP3+ and ILC group 1 (ILC1) cells. These effects were accompanied by a reduction in CD25+FoxP3+ and ILC group 3 (ILC3) cells. By comparison, genetic deletion of DR3 effectively reversed the inflammatory phenotype in SAMP mice by promoting the expansion of CD25+FoxP3+ over CD25-FoxP3+ cells and the production of IL-10 protein. Collectively, our data demonstrate that DR3 signaling modulates a multicellular network, encompassing Tregs, T effectors, and ILCs, governing disease development and progression in SAMP mice with CD-like ileitis. Manipulating DR3 signaling toward the restoration of the balance between protective and inflammatory lymphocytes may represent a novel and targeted therapeutic modality for patients with CD.

Exome-wide association study reveals novel psoriasis susceptibility locus at TNFSF15 and rare protective alleles in genes contributing to type I IFN signalling

Psoriasis is a common inflammatory skin disorder for which multiple genetic susceptibility loci have been identified, but few resolved to specific functional variants. In this study, we sought to identify common and rare psoriasis-associated gene-centric variation. Using exome arrays we genotyped four independent cohorts, totalling 11 861 psoriasis cases and 28 610 controls, aggregating the dataset through statistical meta-analysis. Single variant analysis detected a previously unreported risk locus at TNFSF15 (rs6478108; P = 1.50 × 10-8, OR = 1.10), and association of common protein-altering variants at 11 loci previously implicated in psoriasis susceptibility. We validate previous reports of protective low-frequency protein-altering variants within IFIH1 (encoding an innate antiviral receptor) and TYK2 (encoding a Janus kinase), in each case establishing a further series of protective rare variants (minor allele frequency < 0.01) via gene-wide aggregation testing (IFIH1: pburden = 2.53 × 10-7, OR = 0.707; TYK2: pburden = 6.17 × 10-4, OR = 0.744). Both genes play significant roles in type I interferon (IFN) production and signalling. Several of the protective rare and low-frequency variants in IFIH1 and TYK2 disrupt conserved protein domains, highlighting potential mechanisms through which their effect may be exerted.

A case-control study about the association between vascular endothelial growth inhibitor gene polymorphisms and breast cancer risk in female patients in Northeast China

Objective

The inhibition of the neovascularization in tumors is a potential therapeutic target of cancer. Vascular endothelial growth inhibitor (VEGI) is a member of the TNF superfamily which has the ability to suppress the formation of new vessels in tumors. In order to study the association between VEGI gene polymorphisms and breast cancer risk, a case-control study was conducted in Chinese Han women in Northeast China.

Methods

Our study involved 708 female breast cancer patients and 685 healthy volunteers. Four SNPs of VEGI gene were analyzed through the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The association between VEGI gene polymorphisms and breast cancer risk was analyzed in our study. The relation between VEGI gene variants and clinical features of breast cancer including lymph node (LN) metastasis, estrogen receptor (ER), progestrogen receptor (PR), tumor protein 53 (p53), human epidermal growth factor receptor 2 (Her-2) and triple negative (ER-/PR-/Her-2-) status was analyzed as well.

Results

We found that the CT genotype and T allele of rs6478106 were more frequent in patients than in controls. There was also a statistical difference in the distribution of C_rs6478106G_rs4263839 haplotype between patients and controls. In addition, SNP rs6478106 and rs4979462 were related with the Her-2 status.

Conclusions

Our results suggest that VEGI gene variants may be related to the breast cancer risk and the clinical features of breast cancer in Chinese Han women in Northeast China.

Tumor Necrosis Factor-like Cytokine TL1A and Its Receptors DR3 and DcR3: Important New Factors in Mucosal Homeostasis and Inflammation

Tumor necrosis factor (TNF)-like cytokine 1A (TL1A) is a member of the TNF superfamily of proteins (TNFSF15), which signals through association with death domain receptor 3 (DR3). Decoy receptor 3 (DcR3) competes with DR3 for TL1A binding and inhibits functional signaling. These proteins are significantly upregulated in inflamed intestinal tissues, and their pathogenetic importance for inflammatory bowel disease (IBD) is suggested by accumulating evidence. TL1A/DR3 induce costimulatory signals to activated lymphocytes, including the gut-specific populations of CD4+CD161+ and CD4+CCR9+ cells, affecting all major effector pathways and inducing the mucosal upregulation of Th1, Th2, and Th17 factors. They may also participate in mucosal homeostasis and defense against pathogens through their effects on the development and function of the recently described innate lymphoid cells. T-regulatory lymphocytes highly express DR3, and they respond to TL1A stimulation also. Mechanistic studies by transgenic expression of TL1A, deletion of TL1A or DR3, and therapeutic blockade by anti-TL1A antibodies all support the critical involvement of the corresponding pathways in the pathogenesis of chronic mucosal inflammation. Wide genome association studies have identified IBD-specific polymorphisms in TNFSF15 gene, which have functional implications and serve as poor prognostic factors. Recently, TL1A blockade in mice was presented as a unique pharmacological treatment for the reversal of established intestinal fibrosis. Finally, TL1A/DR3 signaling seems to critically participate in extraintestinal inflammatory conditions that are frequently associated with IBD as part of the gut-joint-skin-eye axis. These converging lines of evidence make TL1A/DR3 a suitable model for personalized approaches to IBD therapy.

The TL1A/DR3/DcR3 pathway in autoimmune rheumatic diseases

IMPORTANCE

TNF-like cytokine 1A (TL1A) and its receptors, death receptor 3 (DR3) and decoy receptor 3 (DcR3) are members of the TNF and TNF receptor superfamilies of proteins, respectively. They constitute a cytokine system that actively interferes with the regulation of immune responses and may participate in the pathogenesis of autoimmune diseases.

OBJECTIVES

This review aims to present the current knowledge on the role of the TL1A/DR3/DcR3 system in the pathophysiology of autoimmune rheumatic diseases, with a focus on rheumatoid arthritis (RA).

METHODS

An extensive literature search was performed in the PubMed database using the following keywords: TL1A, death receptor 3, DR3, decoy receptor 3, DcR3, TNFSF15, TNFRSF25, and TNFSF6B. Studies were assessed and selected in view of their relevance to autoimmune rheumatic diseases.

CONCLUSION

The TL1A/DR3/DcR3 axis is a novel immune pathway that participates in the pathogenesis of a variety of autoimmune rheumatic diseases. These molecules may be promising therapeutic targets for inflammatory arthritis.

What have we learned about non-involved psoriatic skin from large-scale gene expression studies?

Psoriasis is a chronic inflammatory skin disorder; its genetic background has been widely studied in recent decades. Recognition of novel factors contributing to the pathogenesis of this disorder was facilitated by potent molecular biology tools developed during the 1990s. Large-scale gene expression studies, including differential display and microarray, have been used in experimental dermatology to a great extent; moreover, skin was one of the first organs analyzed using these methods. We performed our first comprehensive gene expression analysis in 2000. With the help of differential display and microarray, we have discovered several novel factors contributing to the inherited susceptibility for psoriasis, including the EDA+ fibronectin splice variant and PRINS. The long non-coding PRINS RNA is expressed at higher levels in non-involved skin compared to healthy and involved psoriatic epidermis and might be a factor contributing cellular stress responses and, specifically, to the development of psoriatic symptoms. This review summarizes the most important results of our large-scale gene expression studies.