Sequence and haplotype analysis supports HLA-C as the psoriasis susceptibility 1 gene

Time to transition from psoriasis to psoriatic arthritis: A population-based study

OBJECTIVE

To identify demographic and clinical characteristics associated with time between psoriasis and psoriatic arthritis (PsA).

METHODS

A retrospective, population-based cohort of incident PsA patients ≥18 years (2000-17) from Olmsted County, MN was identified. PsA patients were divided into two groups: patients with concurrent psoriasis and PsA (within 1 year), and patients with psoriasis before PsA (>1 year). Patients with PsA prior to psoriasis were excluded. Age- and sex-adjusted logistic regression models were used to examine factors associated with the time between psoriasis and PsA diagnosis.

RESULTS

Among 164 patients with incident PsA, 158 had a current or personal history of psoriasis. The mean (SD) age at PsA diagnosis was 46.3 (12.0) years, and 46% were females. The median (interquartile range) time from psoriasis to PsA was 35.5 (0.8-153.4) months. 64 patients (41%) patients had concurrent psoriasis and PsA while 94 (59%) had onset of psoriasis before PsA. The estimated age at onset of psoriasis symptom (OR per 10-year decrease = 1.63, 95% CI: 1.26-2.11) and psoriasis severity (OR = 3.65, 95% CI: 1.18-11.32 for severe vs. mild) were associated with having a psoriasis diagnosis more than one year prior to incident PsA.

CONCLUSION

In this population-based study, approximately 60% of the patients had psoriasis before PsA, and the rest had concurrent psoriasis and PsA. Patients with lower age at psoriasis onset or severe psoriasis were more likely to have a longer time to transition from psoriasis to PsA.

Comparison of Efficacy of Anti-interleukin-17 in the Treatment of Psoriasis Between Caucasians and Asians: A Systematic Review and Meta-Analysis

Background

Interleukin-17 (IL-17) monoclonal antibody drugs have been increasingly significant in the treatment of psoriasis, but it is not clear whether the efficacy is equivalent across ethnicities.

Objective

To explore the differences of short-term efficacy of IL-17 inhibitors between Caucasians and Asians.

Methods

The pooled log risk ratio (logRR) between the groups was estimated. The meta-regression analysis on the logRR was performed, with the proportion of Caucasian patients as the covariate. The subgroup analysis was performed by specific IL-17 inhibitors.

Results

Of the 1,569 potentially relevant studies, sixteen randomized controlled trials (RCTs) were included. For the Psoriasis Area and Severity Index 75 (PASI 75) response at week 12, the pooled logRR of the Asian group and the Caucasian group was 2.81 (95% CI: 2.27–3.35, p < 0.001) and 2.93 (95% CI: 2.71–3.16, p < 0.001), respectively, indicating no significant difference of efficacy between Asians and Caucasians. The meta-regression analysis did not show an association of the proportion of Caucasians with the effect size (β = 0.3203, p = 0.334). In the subgroup analysis, the comparison results of secukinumab were consistent with the main analysis.

Limitations

Only the short-term efficacy was explored. The data from Asian countries were limited.

Conclusions

The short-term efficacy of IL-17 inhibitors in the treatment of psoriasis has no significant difference between Caucasians and Asians.

Systematic Review Registration

PROSPERO, identifier CRD42020201994, https://www.crd.york.ac.uk/prospero/.

Immunopathology and Immunotherapy of Inflammatory Skin Diseases

Recently, there have been impressive advancements in understanding of the immune mechanisms underlying cutaneous inflammatory diseases. To understand these diseases on a deeper level and clarify the therapeutic targets more precisely, numerous studies including in vitro experiments, animal models, and clinical trials have been conducted. This has resulted in a paradigm shift from non-specific suppression of the immune system to selective, targeted immunotherapies. These approaches target the molecular pathways and cytokines responsible for generating inflammatory conditions and reinforcing feedback mechanisms to aggravate inflammation. Among the numerous types of skin inflammation, psoriasis and atopic dermatitis (AD) are common chronic cutaneous inflammatory diseases. Psoriasis is a IL-17–mediated disease driven by IL-23, while AD is predominantly mediated by Th2 immunity. Autoimmune bullous diseases are autoantibody-mediated blistering disorders, including pemphigus and bullous pemphigoid. Alopecia areata is an organ-specific autoimmune disease mediated by CD8⁺ T-cells that targets hair follicles. This review will give an updated, comprehensive summary of the pathophysiology and immune mechanisms of inflammatory skin diseases. Moreover, the therapeutic potential of current and upcoming immunotherapies will be discussed.

The HLA-G Immune Checkpoint Plays a Pivotal Role in the Regulation of Immune Response in Autoimmune Diseases

The human G-leukocyte antigen (HLA-G) molecule is a non-classical major histocompatibility complex (MHC) class I molecule. The pertinence of HLA-G has been investigated in numerous studies which have sought to elucidate the relevance of HLA-G in pathologic conditions, such as autoimmune diseases, cancers, and hematologic malignancies. One of the main goals of the current research on HLA-G is to use this molecule in clinical practice, either in diagnostics or as a therapeutic target. Since HLA-G antigens are currently considered as immunomodulatory molecules that are involved in reducing inflammatory and immune responses, in this review, we decided to focus on this group of antigens as potential determinants of progression in autoimmune diseases. This article highlights what we consider as recent pivotal findings on the immunomodulatory function of HLA-G, not only to establish the role of HLA-G in the human body, but also to explain how these proteins mediate the immune response.

ERAP1 Controls the Autoimmune Response against Melanocytes in Psoriasis by Generating the Melanocyte Autoantigen and Regulating Its Amount for HLA-C*06:02 Presentation

Autoimmune diseases develop when autoantigens activate previously quiescent self-reactive lymphocytes. Gene-gene interaction between certain HLA class I risk alleles and variants of the endoplasmic reticulum aminopeptidase ERAP1 controls the risk for common immune-mediated diseases, including psoriasis, ankylosing spondylitis, and Behçet disease. The functional mechanisms underlying this statistical association are unknown. In psoriasis, HLA-C*06:02 mediates an autoimmune response against melanocytes by autoantigen presentation. Using various genetically modified cell lines together with an autoreactive psoriatic TCR in a TCR activation assay, we demonstrate in this study that in psoriasis, ERAP1 generates the causative melanocyte autoantigen through trimming N-terminal elongated peptide precursors to the appropriate length for presentation by HLA-C*06:02. An ERAP1 risk haplotype for psoriasis produced the autoantigen much more efficiently and increased HLA-C expression and stimulation of the psoriatic TCR by melanocytes significantly more than a protective haplotype. Compared with the overall HLA class I molecules, cell surface expression of HLA-C decreased significantly more upon ERAP1 knockout. The combined upregulation of ERAP1 and HLA-C on melanocytes in psoriasis lesions emphasizes the pathogenic relevance of their interaction in patients. We conclude that in psoriasis pathogenesis, the increased generation of an ERAP1-dependent autoantigen by an ERAP1 risk haplotype enhances the likelihood that autoantigen presentation by HLA-C*06:02 will exceed the threshold for activation of potentially autoreactive T cells, thereby triggering CD8+ T cell-mediated autoimmune disease. These data identify ERAP1 function as a central checkpoint and promising therapeutic target in psoriasis and possibly other HLA class I-associated diseases with a similar genetic predisposition.

Costo per responder di risankizumab e secukinumab nel trattamento della psoriasi a placche da moderata a grave in Italia

Purpose:

The objective of this analysis was to compare the cost per responder between risankizumab and secukinumab among patients with moderate-to-severe plaque psoriasis in Italy.

Methods:

The clinical efficacy was assessed based on IMMerge study of published efficacy data as measured by Psoriasis Area and Severity Index response (PASI 90 and PASI 100) for risankizumab and secukinumab. The treatment cost was based on the number of administrations dispensed in the first (induction plus maintenance period) and the second (maintenance period only) year of treatment and the ex-factory price of each treatment. The cost per responder was adopted as a cost-effectiveness indicator.

Results:

Independently of the PASI response (PASI 90 and PASI 100) used and the year of treatment considered, the cost per responder was consistently lower for risankizumab compared to secukinumab in all clinical measures. For example, considering the first-year costs and PASI 100, the cost per responder for risankizumab was € 24,506.83 compared to € 38,000.00 for secukinumab. The differences in the cost per responder between risankizumab and secukinumab increased when higher PASI response levels were considered.

Conclusion:

This economic evaluation suggested that the cost per responder is consistently lower for risankizumab compared to secukinumab from the perspective of the Italian National Health Service in the treatment of moderate-to-severe plaque psoriasis.

New Frontiers in Psoriatic Disease Research, Part I: Genetics, Environmental Triggers, Immunology, Pathophysiology, and Precision Medicine

Psoriasis is a chronic inflammatory condition characterized by systemic immune dysregulation. Over the past several years, advances in genetics, microbiology, immunology, and mouse models have revealed the complex interplay between the heritable and microenvironmental factors that drive the development of psoriatic inflammation. In the first of this two-part review series, the authors will discuss the newest insights into the pathogenesis of psoriatic disease and highlight how the evolution of these scientific fields has paved the way for a more personalized approach to psoriatic disease treatment.

Basic genetic and biological markers of psoriasis

Background. Psoriasis is a chronic inflammatory autoimmune disease characterized by an excessively aberrant hyperproliferation of keratinocytes. The pathogenesis of psoriasis is complex, and the exact mechanism, despite numerous studies, is still unclear. Complex genetic relationships play an important role in the pathogenesis of this skin disease. A large number of genes that are also associated with other diseases are involved in the development of psoriasis. The variety of comorbidities in patients with psoriasis often present challenges to the treatment for dermatosis. Understanding the role of certain genes in the pathogenesis of psoriasis will contribute the development of more effective targeted therapy aimed at blocking the corresponding inflammatory signaling pathways and molecules. Aim. To analyze and systematize the basic genetic and biological markers of psoriasis. Materials and methods. The study included research articles on the genetic analysis of psoriasis. The ResNet, PubMed and eLibrary databases were used. Results and discussion. Basic genetic and biological markers were identified by analysis of literature sources devoted to psoriasis. Attention is paid to the role and effects of single nucleotide polymorphisms, which make it possible to establish a clear association of a number of genes involved in the development of psoriasis. Genes with altered expression in the psoriatic process were considered separately. Conclusion. The identified biomarkers can be used in targeted biological therapy of psoriasis using biological modulators that block signaling.

Psoriasis Susceptibility 1 Candidate 1 (PSORS1C1) Polymorphism is Associated with Autoimmune Thyroid Disease in a Chinese Han Population

BACKGROUND

Autoimmune thyroid disease (AITD) is an inherited, complex gene- and immune-related disorder that mainly includes Graves' disease (GD) and Hashimoto's thyroiditis (HT). Psoriasis susceptibility 1 candidate 1 (PSORS1C1) is a susceptibility gene associated with many autoimmune diseases, but its role in an individual's predisposition to AITD is unknown.

METHODS

This study included 1065 Chinese Han patients with AITD and 943 matched healthy individuals. The rs3130983, rs3778638, rs3815087, and rs4959053 single nucleotide polymorphisms (SNPs) in PSORS1C1 were determined using multiplex polymerase chain reaction technology.

RESULTS

Of the four SNPs, only the distribution of the rs3778638 genotypes was different between the AITD (AA, 2.67%; AG, 19.15%; and GG, 78.18%) and control (AA, 1.52%; AG, 22.2%; and GG, 75.87%) groups (P = .046). An association between rs3778683 and GD was observed (p = .039) but not with HT. No linkage disequilibrium was observed for rs3130983, rs3815087, rs3778638, and rs4959053 in PSORS1C1 among the patients with AITD and controls.

CONCLUSION

This study suggests the influence of PSORS1C1 rs3778638 on the susceptibility to GDs, supporting this locus as a common autoimmunity risk factor.

Thrombosis in Psoriasis: Cutaneous Cytokine Production as a Potential Driving Force of Haemostatic Dysregulation and Subsequent Cardiovascular Risk

Psoriasis (PsO) is a common T cell-mediated inflammatory disorder of the skin with an estimated prevalence of 2%. The condition manifests most commonly as erythematous plaques covered with scales. The aetiology of PsO is multifactorial and disease initiation involves interactions between environmental factors, susceptibility genes, and innate and adaptive immune responses. The underlying pathology is mainly driven by interleukin-17. In addition, various inflammatory mediators from specific T helper (T_H) cell subsets, namely T_H1, T_H17, and T_H22, are overexpressed in cutaneous lesions and may also be detected in the peripheral blood of psoriatic patients. Moreover, these individuals are also at greater risk, compared to the general population, of developing multiple comorbid conditions. Cardiovascular disease (CVD) has been recognised as a prominent comorbidity of PsO. A potential mechanism contributing to this association may be the presence of a hypercoagulable state in these individuals. Inflammation and coagulation are closely related. The presence of chronic, low-grade systemic inflammation may promote thrombosis – one of the major determinants of CVD. A pro-inflammatory milieu may induce the expression of tissue factor, augment platelet activity, and perturb the vascular endothelium. Altogether, these changes will result in a prothrombotic state. In this review, we describe the aetiology of PsO, as well as the pathophysiology of the condition. We also consider its relationship to CVD. Given the systemic inflammatory nature of PsO, we evaluate the potential contribution of prominent inflammatory mediators (implicated in PsO pathogenesis) to establishing a prothrombotic state in psoriatic patients.

Therapeutic Development Based on the Immunopathogenic Mechanisms of Psoriasis

Psoriasis, a complex inflammatory autoimmune skin disorder that affects 2–3% of the global population, is thought to be genetically predetermined and induced by environmental and immunological factors. In the past decades, basic and clinical studies have significantly expanded knowledge on the molecular, cellular, and immunological mechanisms underlying the pathogenesis of psoriasis. Based on these pathogenic mechanisms, the current disease model emphasizes the role of aberrant Th1 and Th17 responses. Th1 and Th17 immune responses are regulated by a complex network of different cytokines, including TNF-α, IL-17, and IL-23; signal transduction pathways downstream to the cytokine receptors; and various activated transcription factors, including NF-κB, interferon regulatory factors (IRFs), and signal transducer and activator of transcriptions (STATs). The biologics developed to specifically target the cytokines have achieved a better efficacy and safety for the systemic management of psoriasis compared with traditional treatments. Nevertheless, the current therapeutics can only alleviate the symptoms; there is still no cure for psoriasis. Therefore, the development of more effective, safe, and affordable therapeutics for psoriasis is important. In this review, we discussed the current trend of therapeutic development for psoriasis based on the recent discoveries in the immune modulation of the inflammatory response in psoriasis.

Functional Mapping of Genetic Interactions between HLA-Cw6 and LCE3A in Psoriasis

Functional studies to delineate the molecular mechanisms of causal genetic variants are the main focus in the post-GWAS era. Previous GWASs have identified >50 susceptibility loci associated with psoriasis. Functional understanding of the biology underlying the disease risk of most of these associated loci is unclear. In this study, we identified a regulatory SNP at the putative enhancer of the LCE3A gene within the epidermal differentiation complex that showed epistatic interaction with HLA-Cw6. The variant allele disrupted signal transducer and activator of transcription 3 binding to the region, thereby regulating the expression of the downstream LCE3A gene. Electrophoretic mobility shift and pulldown assay confirmed the preferential binding of signal transducer and activator of transcription 3 to the DNA with a wild-type allele compared with the DNA with a variant allele. The reporter assay further validated the IL-6‒stimulated phosphorylated signal transducer and activator of transcription 3‒mediated LCE3A activation in the presence of the wild-type allele. Interestingly, the presence of the HLA-Cw6 allele leads to IL-6‒mediated phosphorylation of signal transducer and activator of transcription 3, followed by its nuclear localization in the epidermal keratinocytes of psoriatic skin, suggesting indirect interaction of the HLA-Cw6 allele and a regulatory SNP upstream of the LCE3A gene. This study reflects an interesting approach to dissecting the molecular mechanism underlying the genetic interaction observed between HLA-Cw6 and LCE3A in psoriasis pathogenesis.

MHC class I associations beyond HLA-B27: the peptide binding hypothesis of psoriatic arthritis and its implications for disease pathogenesis

PURPOSE OF REVIEW

To provide an overview of the heterogeneous human leucocyte antigen (HLA) associations of psoriatic arthritis, their relationship to particular clinical features of the disease, and how a hypothesis of binding specific peptides could provide a unifying basis for this heterogeneity.

RECENT FINDINGS

There have been substantive advances in understanding the role of HLA molecules in binding self-peptides that select our repertoire of T cells, the specific peptide-binding properties of these HLA allotypes, and their crystallographic structure. These advances provide a means to envision the significance of the heterogeneous psoriatic arthritis HLA associations. The clinical relevance of these allotypes if heightened by emerging knowledge of their relationship to particular clinical features of the disease that serve as subphenotypes.

SUMMARY

We propose a peptide binding hypothesis of psoriatic arthritis based on a shared pattern of negative charge in the 'B' pocket of the HLA-B and HLA-C molecules encoded by the susceptibility allotypes. This hypothesis suggests that peptides characterized by the presence of arginine at position 2 or 3 are bound to the susceptibility allotypes and drive the T-cell clones selected on them to attack molecules containing these peptides located in sites of psoriatic arthritis inflammation.

PD-1 Expression Defines Epidermal CD8+CD103+ T Cells Preferentially Producing IL-17A and Using Skewed TCR Repertoire in Psoriasis

In psoriasis, CD8⁺CD103⁺ memory T cells residing in the epidermis represent an effector population capable of maintaining the condition and driving a recurrence of the disease. Tissue-infiltrating CD8⁺ T cells expressing PD-1 are regarded as antigen-primed effector cells in others chronic inflammatory diseases. However, the expression and significance of PD-1 on skin-infiltrating CD8⁺ T cells in human psoriasis is not known. By analyzing skin-infiltrating T cells from human psoriasis, we found that active psoriatic epidermis contained PD-1 expressing CD8⁺CD103⁺ T cells that correlated with the disease severity and histopathology. PD-1⁺CD8⁺CD103⁺ T cells possessed a canonical psoriasis-specific resident memory phenotype with IL-23R expression and produced IL-17A, whereas PD-1^-CD8⁺CD103⁺ T cells preferentially produced IFN-γ. The diversity of skin-infiltrating T cells was dominated by CD4⁺ T cells, while CD8⁺ T cells, especially CD8⁺CD103⁺T cells, represented an oligoclonal population in active psoriasis. In addition, PD-1⁺CD8⁺CD103⁺T cells used different TCR Vβs from PD-1^-CD8⁺CD103⁺T cells counterpart. In the early resolved lesion, the composition and functional status of PD-1⁺CD8⁺CD103⁺T cells were markedly altered, while PD-1^-CD8⁺CD103⁺ T cells population was minimally changed. Collectively, PD-1 expression delineates a putative pathogenic subset of epidermal CD8⁺CD103⁺ T cells, which possibly play a role in psoriasis pathogenesis.

Psoriasis

Psoriasis is a common, chronic papulosquamous skin disease occurring worldwide, presenting at any age, and leading to a substantial burden for individuals and society. It is associated with several important medical conditions, including depression, psoriatic arthritis, and cardiometabolic syndrome. Its most common form, chronic plaque or psoriasis vulgaris, is a consequence of genetic susceptibility, particularly in the presence of the HLA-C*06:02 risk allele, and of environmental triggers such as streptococcal infection, stress, smoking, obesity, and alcohol consumption. There are several phenotypes and research has separated pustular from chronic plaque forms. Immunological and genetic studies have identified IL-17 and IL-23 as key drivers of psoriasis pathogenesis. Immune targeting of these cytokines and of TNFα by biological therapies has revolutionised the care of severe chronic plaque disease. Psoriasis cannot currently be cured, but management should aim to minimise physical and psychological harm by treating patients early in the disease process, identifying and preventing associated multimorbidity, instilling lifestyle modifications, and employing a personalised approach to treatment.

m6A RNA Methylation in Systemic Autoimmune Diseases-A New Target for Epigenetic-Based Therapy?

The general background of autoimmune diseases is a combination of genetic, epigenetic and environmental factors, that lead to defective immune reactions. This erroneous immune cell activation results in an excessive production of autoantibodies and prolonged inflammation. During recent years epigenetic mechanisms have been extensively studied as potential culprits of autoreactivity. Alike DNA and proteins, also RNA molecules are subjected to an extensive repertoire of chemical modifications. N6-methyladenosine is the most prevalent form of internal mRNA modification in eukaryotic cells and attracts increasing attention due to its contribution to human health and disease. Even though m6A is confirmed as an essential player in immune response, little is known about its role in autoimmunity. Only few data have been published up to date in the field of RNA methylome. Moreover, only selected autoimmune diseases have been studied in respect of m6A role in their pathogenesis. In this review, I attempt to present all available research data regarding m6A alterations in autoimmune disorders and appraise its role as a potential target for epigenetic-based therapies.

Major Role of the IL17/23 Axis in Psoriasis Supports the Development of New Targeted Therapies

Psoriasis is a frequent, chronic disease characterized by cutaneous inflammatory plaques and/or arthritis. It may be associated with few other diseases, mainly Crohn’s disease and metabolic syndrome. The medical and psychosocial burden of psoriasis remains high even since biological treatments arose, stressing that efforts to decipher its physiopathology are constantly needed. Tumor-necrosis factor α, interleukin (IL) 12 and IL17 have been previously associated with psoriasis and successfully targeted by monoclonal antibodies. IL17 in particular has been initially described as a T helper (Th) 17—produced cytokine, but it is now established that other cell types, such as γδ T lymphocytes, Mucosal-Associated Invariant T (MAIT) cells and Innate Lymphoïd Cells (ILC) 3 are also important sources of IL17 in the skin in response to inflammatory stimuli. Th17 phenotype has been shown to be stabilized by IL23, which is synthetized by macrophages and dendritic cells in response to Toll Like Receptors and C-type Lectin Receptors stimulation. Recent data also reported a crucial role for IL23 in MAIT17 and ILC3 homeostasis. Genome-wide association studies have found a significant link between IL23 receptor polymorphism and psoriasis susceptibility. IL23 signals through Janus kinase 2 and Tyrosine kinase 2, against which specific inhibitors are currently being tested. Monoclonal antibodies against IL17 and IL23 are only the beginning of a new avenue in psoriasis treatment. This review focuses on the molecular basis underlying IL23/IL17 axis blockade in psoriasis, and on future targets in this pathway.

Therapeutics targeting the IL-23 and IL-17 pathway in psoriasis

Psoriasis is a chronic inflammatory disease characterised by sharply demarcated erythematous and scaly skin lesions accompanied by systemic manifestations. Classified by WHO as one of the most serious non-infectious diseases, psoriasis affects 2-3% of the global population. Mechanistically, psoriatic lesions result from hyperproliferation and disturbed differentiation of epidermal keratinocytes that are provoked by immune mediators of the IL-23 and IL-17 pathway. Translational immunology has had impressive success in understanding and controlling psoriasis. Psoriasis is the first disease to have been successfully treated with therapeutics that directly block the action of the cytokines of this pathway; in fact, therapeutics that specifically target IL-23, IL-17, and IL-17RA are approved for clinical use and show excellent efficacy. Furthermore, inhibitors of IL-23 and IL-17 intracellular signalling, such as TYK2 or RORγt, are in clinical development. Although therapies that target the IL-23 and IL-17 pathway also improve psoriatic arthritis symptoms, their effects on long-term disease modification and psoriasis-associated comorbidities still need to be explored.

SNP-Density Crossover Maps of Polymorphic Transposable Elements and HLA Genes Within MHC Class I Haplotype Blocks and Junction

The genomic region (~4 Mb) of the human major histocompatibility complex (MHC) on chromosome 6p21 is a prime model for the study and understanding of conserved polymorphic sequences (CPSs) and structural diversity of ancestral haplotypes (AHs)/conserved extended haplotypes (CEHs). The aim of this study was to use a set of 95 MHC genomic sequences downloaded from a publicly available BioProject database at NCBI to identify and characterise polymorphic human leukocyte antigen (HLA) class I genes and pseudogenes, MICA and MICB, and retroelement indels as haplotypic lineage markers, and single-nucleotide polymorphism (SNP) crossover loci in DNA sequence alignments of different haplotypes across the Olfactory Receptor (OR) gene region (~1.2 Mb) and the MHC class I region (~1.8 Mb) from the GPX5 to the MICB gene. Our comparative sequence analyses confirmed the identity of 12 haplotypic retroelement markers and revealed that they partitioned the HLA-A/B/C haplotypes into distinct evolutionary lineages. Crossovers between SNP-poor and SNP-rich regions defined the sequence range of haplotype blocks, and many of these crossover junctions occurred within particular transposable elements, lncRNA, OR12D2, MUC21, MUC22, PSORS1A3, HLA-C, HLA-B, and MICA. In a comparison of more than 250 paired sequence alignments, at least 38 SNP-density crossover sites were mapped across various regions from GPX5 to MICB. In a homology comparison of 16 different haplotypes, seven CEH/AH (7.1, 8.1, 18.2, 51.x, 57.1, 62.x, and 62.1) had no detectable SNP-density crossover junctions and were SNP poor across the entire ~2.8 Mb of sequence alignments. Of the analyses between different recombinant haplotypes, more than half of them had SNP crossovers within 10 kb of LTR16B/ERV3-16A3_I, MLT1, Charlie, and/or THE1 sequences and were in close vicinity to structurally polymorphic Alu and SVA insertion sites. These studies demonstrate that (1) SNP-density crossovers are associated with putative ancestral recombination sites that are widely spread across the MHC class I genomic region from at least the telomeric OR12D2 gene to the centromeric MICB gene and (2) the genomic sequences of MHC homozygous cell lines are useful for analysing haplotype blocks, ancestral haplotypic landscapes and markers, CPSs, and SNP-density crossover junctions.

Identification of protein/mRNA network involving the PSORS1 locus gene CCHCR1 and the PSORS4 locus gene HAX1

CCHCR1 (Coiled-Coil alpha-Helical Rod 1), maps to chromosomal region 6p21.3, within the major psoriasis susceptibility locus PSORS1. CCHCR1 itself is a plausible psoriasis candidate gene, however its role in psoriasis pathogenesis remains unclear. We previously demonstrated that CCHCR1 protein acts as a cytoplasmic docking site for RNA polymerase II core subunit 3 (RPB3) in cycling cells, suggesting a role for CCHCR1 in vesicular trafficking between cellular compartments. Here, we report a novel interaction between CCHCR1 and the RNA binding protein HAX1. HAX1 maps to chromosomal region 1q21.3 within the PSORS4 locus and is over-expressed in psoriasis. Both CCHCR1 and HAX1 share subcellular co-localization with mitochondria, nuclei and cytoplasmic vesicles as P-bodies. By a series of ribonucleoprotein immunoprecipitation (RIP) assays, we isolated a pool of mRNAs complexed with HAX1 and/or CCHCR1 proteins. Among the mRNAs complexed with both CCHCR1 and HAX1 proteins, there are Vimentin mRNA, previously described to be bound by HAX1, and CAMP/LL37 mRNA, whose gene product is over-expressed in psoriasis.

A Large-Scale, Stratified Genetic Analysis of the Major Histocompatibility Complex Region in Early- and Late-Onset Psoriasis in China

Background

Psoriasis vulgaris is a chronic inflammatory skin disease which occur at any age. It can be clinically classified into two age-onset subtypes: early-onset psoriasis (EOP; <40 years) and late-onset psoriasis (LOP; ≥40 years). More evidence showed EOP and LOP have different genetic architecture, notably the risk allele human leukocyte antigen (HLA)-C^*06:02 located within the major histocompatibility complex (MHC) region, which was reported to be the outstanding variant associated with EOP. However, genetic structure of EOP and LOP have not been fully elucidated.

Objective

To investigated HLA genetic heterogeneity between EOP and LOP in China.

Methods

We first calculated the MHC-based heritability of EOP and LOP respectively. Then, we conducted a large-scale, stratified analysis including 7,097 EOP, 1,337 LOP patients, and 9,906 healthy controls by using MHC target sequencing data from a previous study.

Results

We observed that HLA alleles collectively explained a larger heritability of EOP (27.4%) than LOP (11.3%). Further association analysis identified three independent loci (HLA-C^*01:02, p=6.70×10⁻⁸; HLA-A amino acid position 9, p=3.27×10⁻¹⁷; and HLA-A amino acid position 161, p=5.75×10⁻¹⁰) that confer specific susceptibility to EOP. Our data also confirmed HLA-C^*06:02 as an independent psoriasis-associated variant, contributing a higher degree of risk to EOP than LOP. Moreover, case-case analysis confirmed that HLA-C^*06:02-positive psoriasis patients have earlier onset.

Conclusion

Our analysis indicating that different genetic background underlie the EOP and LOP. We believe these findings will serve to predict psoriasis risk in the future and facilitate clinical decision.

Assessment of CLA+T-cell subpopulations in the blood of patients with chronic dermatoses

Background. CLA+T-cell are an important component of skin-associated lymphoid tissue, and thus determine the pathogenesis of many immuno-mediated dermatoses. Aims. Determine the relative number of CLA+T-cell subpopulations in the peripheral blood of patients with psoriasis, lichen planus and atopic dermatitis, as well as assess their impact on the severity of dermatoses. Materials and methods. We examined 82 patients with psoriasis aged 19 to 62 years, 54 patients with lichen planus (LP) aged 18 to 54 years, 44 patients with atopic dermatitis (AD) aged 18 to 44 years, as well as 20 practically healthy individuals aged 18 to 52 years who were admitted to the clinic for the removal of benign skin neoplasms. All patients underwent a standard clinical examination with the determination of indicators that characterize the severity of dermatosis: PASI (Psoriasis Area and Severity Index) for patients with psoriasis, IPSLP (index of prevalence and severity of lichen planus) for patients with lichen planus and SCORAD (Scoring of Atopic Dermatitis) for patients with atopic dermatitis. Defining subpopulations CLA+T-lymphocytes were carried out on a flow cytometer Cytomics FC500 by Beckman Coulter using appropriate combinations of direct monoclonal antibodies and isotopic controls. The groups were compared using the nonparametric Mann Whitney test, and the differences were considered significant at p0,05. To analyze the relationship between the severity of dermatosis and the relative content of subpopulations CLA+T-cells used Spearman's rank correlation coefficient. Results. In patients with psoriasis, a significant increase in the percentage of the total number of T-lymphocytes positive for CLA (CLA+CD3+) and T-helpers positive for CLA (CLA+CD4+) (p=0,002 and 8,5104, respectively), in patients with PL and AD only CLA+CD4+ lymphocytes (p=0,028 and 0,003, respectively). In the progressive period of psoriasis, a direct moderate correlation was found between the circulating subpopulation of cytotoxic T lymphocytes positive for CLA (CLA+CD8+) and the PASI index (rs=0,47; p0,001), in the acute period of AD between the CLA+CD3+ subpopulations and CLA+CD4+ cells and the SCORAD index (rs=0,53; p 0,001 and rs=0,57; p0,001, respectively). In PL, the severity of the course of dermatosis was not accompanied by any significant changes in the CLA-positive T-cell subpopulations. Conclusion. The results of the study confirmed the important role of CLA+T cell subpopulations in the development of chronic dermatoses. In all groups (psoriasis, LP and AD), an increase in the relative number of CLA+CD4+ T-helpers was noted compared with the control group. The relationship between the severity of psoriasis and the relative number of CLA+CD8+ cytotoxic T-lymphocytes, and the severity of AD with CLA+CD3+ and CLA+CD4+ T-helpers is also shown.

Which Way Do We Go? Complex Interactions in Atopic Dermatitis Pathogenesis

Atopic dermatitis (AD) is a common, chronic, inflammatory skin condition characterized by recurrent and pruritic skin eruptions. Multiple factors contribute to the pathogenesis of AD, including skin barrier dysfunction, microbial dysbiosis, and immune dysregulation. Interactions among these factors form a complex, multidirectional network that can reinforce atopic skin disease but can also be ameliorated by targeted therapies. This review summarizes the complex interactions among contributing factors in AD and the implications on disease development and therapeutic interventions.

Neonatal genetics of gene expression reveal potential origins of autoimmune and allergic disease risk

Chronic immune-mediated diseases of adulthood often originate in early childhood. To investigate genetic associations between neonatal immunity and disease, we map expression quantitative trait loci (eQTLs) in resting myeloid cells and CD4⁺ T cells from cord blood samples, as well as in response to lipopolysaccharide (LPS) or phytohemagglutinin (PHA) stimulation, respectively. Cis-eQTLs are largely specific to cell type or stimulation, and 31% and 52% of genes with cis-eQTLs have response eQTLs (reQTLs) in myeloid cells and T cells, respectively. We identified cis regulatory factors acting as mediators of trans effects. There is extensive colocalisation between condition-specific neonatal cis-eQTLs and variants associated with immune-mediated diseases, in particular CTSH had widespread colocalisation across diseases. Mendelian randomisation shows causal neonatal gene expression effects on disease risk for BTN3A2, HLA-C and others. Our study elucidates the genetics of gene expression in neonatal immune cells, and aetiological origins of autoimmune and allergic diseases.

Some immune-mediated diseases may originate in early childhood. The authors mapped eQTLs and response eQTLs to various stimuli in neonatal myeloid cells and T cells, and revealed their potential role in immune-mediated diseases using colocalisation and Mendelian randomisation.

Psoriasis and IgE-mediated allergy: correlation or mutual inhibition? : A prospective cohort study in patients with mild or moderate to severe psoriasis

BACKGROUND

Psoriasis is an autoimmune disease caused by overactivation of T_H1 (Type 1 helper cells) and T_H17 (T helper 17) cells. Overactivation of T_H1 cells inhibits the activity of T_H2 cells involved in type 1 allergies, therefore, psoriasis patients might be less affected by type 1 allergies. This study tested if allergies were less frequent in patients with moderate to severe than with mild psoriasis.

METHODS

Psoriasis patients at the study site reported possible allergy symptoms and were tested for common allergens by skin prick test and IgE levels. Psoriasis was classified by PASI scores (Psoriasis Area and Severity Index) as mild (PASI <10) or moderate/severe (PASI ≥10). Patients without systemic therapy were assessed separately. Fisher's exact test was used to test for differences.

RESULTS

A total of 97 patients were included, 21 with mild and 76 with moderate to severe psoriasis. Allergies were found in 27.8%, most commonly against dust mites (23.4%) and grasses (18.1%). Allergies were found in 23.8% of the patients with mild vs. 29.0% allergic patients with moderate to severe psoriasis (P = 0.786). In patients without systemic medication, allergies were found in 21.1% vs. 35.3% (P = 0.463).

CONCLUSION

Allergy prevalence was not reduced in patients with moderate/severe psoriasis, and generally close to the prevalence in the general Austrian population (24%). The inhibiting effect of psoriasis on type 1 allergies was not confirmed.

Pathogenesis of psoriasis in the "omic" era. Part II. Genetic, genomic and epigenetic changes in psoriasis

Psoriasis is a multifactorial disease in which genetic, environmental and epigenetic factors regulating gene expression play a key role. In the “genomic era”, genome-wide association studies together with target genotyping platforms performed in different ethnic populations have found more than 50 genetic susceptible markers associated with the risk of psoriasis which have been identified so far. Up till now, the strongest association with the risk of the disease has been proved for HLA-C*06 gene. The majority of other psoriasis risk SNPs are situated near the genes encoding molecules involved in adaptive and innate immunity, and skin barrier function. Many contemporary studies indicate that the epigenetic changes: histone modification, promoter methylations, long non-coding and micro-RNA hyperexpression are considered as factors contributing to psoriasis pathogenesis as they regulate abnormal keratinocyte differentiation and proliferation, aberrant keratinocytes – inflammatory cells communication, neoangiogenesis and chronic inflammation. The circulating miRNAs detected in the blood may become specific markers in the diagnosis, prognosis and response to the treatment of the disease. The inhibition of expression in selected miRNAs may be a new promising therapy option for patients with psoriasis.

The current landscape of psoriasis genetics in 2020

Psoriasis is an immune-mediated disease associated with skin and joint inflammation that affects large proportions of populations worldwide. It is a heritable disease: individuals' genetic backgrounds modulate their susceptibility. In genetics, multiple human leukocyte antigen (HLA) genes are most strongly associated with the risk of psoriasis, especially HLA-C*06:02. In the last 10 years, large-scale genome-wide association studies (GWASs) of psoriasis have been conducted in multiple populations, and these have substantially increased the number of genetic loci associated with psoriasis susceptibility (n > 80). Understanding the genetic background of psoriasis is important for understanding the disease's biology, identifying clinical biomarkers, discovering novel drug targets, and accelerating the journey towards personalized medicine. However, the application of whole-genome and long-read sequencing technology in psoriasis genetic analysis is still developing. Moreover, achieving practical strategies for translating psoriasis risk-associated genetic variants into functional annotations and clinical applications remains challenging. In this review, we detail the current and future landscape of psoriasis genetics and introduce the cutting-edge use of large-scale GWAS data, especially in the Japanese population.

Cytokines in psoriasis

Psoriasis is chronic, immune-mediated, inflammatory disease with a multifactorial etiology that affects the skin tissue and causes the appearance of dry and scaly lesions of anywhere on the body. The study of the pathophysiology of psoriasis reveals a network of immune cells that, together with their cytokines, initiates a chronic inflammatory response. Previously attributed to T helper (Th)1 cytokines, currently the Th17 cytokine family is the major effector in the pathogenesis of psoriatic disease and strongly influences the inflammatory pattern established during the disease activity. In addition, the vast network of cells that orchestrates the pathophysiology makes psoriasis complex to study. Along with this, variations in genes that code the cytokines make psoriasis more clinically heterogeneous and present a challenge for the development of drugs that can be used in the treatment of the patients with this disease. Therefore, it is important to clarify the mechanisms by which the cytokines are involved in the pathophysiology of psoriasis and how this knowledge is translated to the medical practice.

Pathophysiology, Clinical Presentation, and Treatment of Psoriasis: A Review

IMPORTANCE

Approximately 125 million people worldwide have psoriasis. Patients with psoriasis experience substantial morbidity and increased rates of inflammatory arthritis, cardiometabolic diseases, and mental health disorders.

OBSERVATIONS

Plaque psoriasis is the most common variant of psoriasis. The most rapid advancements addressing plaque psoriasis have been in its pathogenesis, genetics, comorbidities, and biologic treatments. Plaque psoriasis is associated with a number of comorbidities including psoriatic arthritis, cardiometabolic diseases, and depression. For patients with mild psoriasis, topical agents remain the mainstay of treatment, and they include topical corticosteroids, vitamin D analogues, calcineurin inhibitors, and keratolytics. The American Academy of Dermatology-National Psoriasis Foundation guidelines recommend biologics as an option for first-line treatment of moderate to severe plaque psoriasis because of their efficacy in treating it and acceptable safety profiles. Specifically, inhibitors to tumor necrosis factor α (TNF-α) include etanercept, adalimumab, certolizumab, and infliximab. Other biologics inhibit cytokines such as the p40 subunit of the cytokines IL-12 and IL-13 (ustekinumab), IL-17 (secukinumab, ixekizumab, bimekizumab, and brodalumab), and the p19 subunit of IL-23 (guselkumab, tildrakizumab, risankizumab, and mirikizumab). Biologics that inhibit TNF-α, p40IL-12/23, and IL-17 are also approved for the treatment of psoriatic arthritis. Oral treatments include traditional agents such as methotrexate, acitretin, cyclosporine, and the advanced small molecule apremilast, which is a phosphodiesterase 4 inhibitor. The most commonly prescribed light therapy used to treat plaque psoriasis is narrowband UV-B phototherapy.

CONCLUSIONS AND RELEVANCE

Psoriasis is an inflammatory skin disease that is associated with multiple comorbidities and substantially diminishes patients' quality of life. Topical therapies remain the cornerstone for treating mild psoriasis. Therapeutic advancements for moderate to severe plaque psoriasis include biologics that inhibit TNF-α, p40IL-12/23, IL-17, and p19IL-23, as well as an oral phosphodiesterase 4 inhibitor.

Recent genetic advances in innate immunity of psoriatic arthritis

Psoriatic arthritis (PsA) is a heterogeneous disease that affects multiple organ systems including the peripheral and axial joints, entheses and nails. PsA is associated with significant comorbidities including cardiovascular, metabolic, and psychiatric diseases. The pathogenesis of PsA is complex and involves genetic, immunologic and environmental factors. Recent evidence suggests the heritability for PsA to be stronger and distinct from that of PsC. Prominent genes identified via GWAS for PsA include HLA-B/C, HLAB, IL12B, IL23R, TNP1, TRAF3IP3, and REL. We review the genetics of psoriatic arthritis and discuss the role of the innate immune system as important in the pathogenesis of PsA by focusing on key signaling pathways and cellular makeup. Understanding the candidate genes identified in PsA highlights pathways of critical importance to the pathogenesis of psoriatic disease including the key role of the innate immune response, mediated through IL-23/IL-17 axis, RANK and NFκB signaling pathways.

The pathogenic role of innate lymphoid cells in autoimmune-related and inflammatory skin diseases

Innate lymphoid cells (ILCs), as an important component of the innate immune system, arise from a common lymphoid progenitor and are located in mucosal barriers and various tissues, including the intestine, skin, lung, and adipose tissue. ILCs are heterogeneous subsets of lymphocytes that have emerging roles in orchestrating immune response and contribute to maintain metabolic homeostasis and regulate tissue inflammation. Currently, more details about the pathways for the development and differentiation of ILCs have largely been elucidated, and cytokine secretion and downstream immune cell responses in disease pathogenesis have been reported. Recent research has identified that several distinct subsets of ILCs at skin barriers are involved in the complex regulatory network in local immunity, potentiating adaptive immunity and the inflammatory response. Of note, additional studies that assess the effects of ILCs are required to better define how ILCs regulate their development and functions and how they interact with other immune cells in autoimmune-related and inflammatory skin disorders. In this review, we will distill recent research progress in ILC biology, abnormal functions and potential pathogenic mechanisms in autoimmune-related skin diseases, including systemic lupus erythematosus (SLE), scleroderma and inflammatory diseases, as well as psoriasis and atopic dermatitis (AD), thereby giving a comprehensive review of the diversity and plasticity of ILCs and their unique functions in disease conditions with the aim to provide new insights into molecular diagnosis and suggest potential value in immunotherapy.

Keratinocytes Derived from Patient-Specific Induced Pluripotent Stem Cells Recapitulate the Genetic Signature of Psoriasis Disease

Psoriasis is characterized by hyperproliferation and defective differentiation of keratinocytes (KCs). Patients with psoriasis are at a high risk of developing diabetes and cardiovascular diseases. The debate on the genetic origin of psoriasis pathogenesis remains unresolved due to lack of suitable in vitro human models mimicking the disease phenotypes. In this study, we provide the first human induced pluripotent stem cell (iPSC) model for psoriasis carrying the genetic signature of the patients. iPSCs were generated from patients with psoriasis (PsO-iPSCs) and healthy donors (Ctr-iPSCs) and were efficiently differentiated into mature KCs. RNA sequencing of KCs derived from Ctr-iPSCs and PsO-iPSCs identified 361 commonly upregulated and 412 commonly downregulated genes. KCs derived from PsO-iPSCs showed dysregulated transcripts associated with psoriasis and KC differentiation, such as HLA-C, KLF4, chemokines, type I interferon-inducible genes, solute carrier family, IVL, DSG1, and HLA-DQA1, as well as transcripts associated with insulin resistance, such as IRS2, GDF15, GLUT10, and GLUT14. Our data suggest that the KC abnormalities are the main driver triggering psoriasis pathology and highlights the substantial contribution of genetic predisposition in the development of psoriasis and insulin resistance.

Genome-wide DNA methylation meta-analysis in the brains of suicide completers

Suicide is the second leading cause of death globally among young people representing a significant global health burden. Although the molecular correlates of suicide remains poorly understood, it has been hypothesised that epigenomic processes may play a role. The objective of this study was to identify suicide-associated DNA methylation changes in the human brain by utilising previously published and unpublished methylomic datasets. We analysed prefrontal cortex (PFC, n = 211) and cerebellum (CER, n = 114) DNA methylation profiles from suicide completers and non-psychiatric, sudden-death controls, meta-analysing data from independent cohorts for each brain region separately. We report evidence for altered DNA methylation at several genetic loci in suicide cases compared to controls in both brain regions with suicide-associated differentially methylated positions enriched among functional pathways relevant to psychiatric phenotypes and suicidality, including nervous system development (PFC) and regulation of long-term synaptic depression (CER). In addition, we examined the functional consequences of variable DNA methylation within a PFC suicide-associated differentially methylated region (PSORS1C3 DMR) using a dual luciferase assay and examined expression of nearby genes. DNA methylation within this region was associated with decreased expression of firefly luciferase but was not associated with expression of nearby genes, PSORS1C3 and POU5F1. Our data suggest that suicide is associated with DNA methylation, offering novel insights into the molecular pathology associated with suicidality.

The Woronoff Ring in Psoriasis and the Mechanisms of Postinflammatory Hypopigmentation

The Woronoff ring is a ring-like hypopigmentation zone around regressing psoriasis lesions. Although it was first described more than 100 years ago, its aetiology has remained a mystery. Recent insights into the pathogenesis of psoriasis can now explain the origin of the Woronoff ring. Psoriasis involves an HLA-class I-restricted autoimmune response of CD8+ T cells against melanocytes in the epidermis. The pathogenic CD8+ T cells are not cytotoxic, but are characterized by the production of interleukin-17, interleukin-22 and tumour necrosis factor-α. Interleukin-17 and tumour necrosis factor-α act synergistically on melanocytes by increasing proliferation while inhibiting melanogenesis. This reduces the cellular melanin content despite an increased number of melanocytes in psoriatic lesions. As a consequence, during healing the prior influence of interleukin-17 and tumour necrosis factor-α, despite the increased density of melanocytes, leaves a hypopigmented zone at the edge of regressing psoriasis lesions, which becomes visible as the Woronoff ring. This mechanism can explain a long-discussed puzzling phenomenon in dermatology.

Pathophysiology of Atopic Dermatitis and Psoriasis: Implications for Management in Children

Atopic dermatitis (AD) and psoriasis are chronic inflammatory skin diseases associated with a significant cutaneous and systemic burden of disease as well as a poor health-related quality of life. Here, we review the complex pathophysiology of both AD and psoriasis and discuss the implications for treatment with current state-of-the-art and emerging topical and systemic therapies. Both AD and psoriasis are caused by a complex combination of immune dysregulation, skin-barrier disruption, genetic factors, and environmental influences. Previous treatments for both diseases were limited to anti-inflammatory agents that broadly suppress inflammation. Emerging insights into relevant pathways, including recognition of the role of T-helper type 2 driven inflammation in AD and T-helper 1 and 17 driven inflammation in psoriasis, have led to a therapeutic revolution. There are a number of novel treatment options available for AD and psoriasis with many more currently under investigation.

Functional significance of MAIT cells in psoriatic arthritis

BACKGROUND

Mucosal-associated invariant T (MAIT) cells are gaining more relevance for autoimmune diseases because of its (i) innate and adaptive immune response (ii) tissue homing properties (iii) production of IL-17A. These cells are predominantly CD8⁺ cells, because of its strong association with MHC-I. Tc17 CD8+/MAIT cells likely to have a critical role in psoriatic arthritis (PsA). Herein, we have explored pathological significance of MAIT cell in PsA.

METHODS

Peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) were collected from age/sex matched (n = 10 for each) PsA, rheumatoid arthritis (RA) and osteoarthritis patients (OA). Hi-D FACS studies were performed: (i) activated memory cells (CD3⁺CD45RO⁺) T cells were identified (ii) gating strategies were made to identity the MAIT (CD3⁺Vα7.2TCR⁺CD161^hi) cells, its phenotype pattern; and functional significance in respect to IL-17A production and responsiveness to human rIL-23. Anti CD3/CD28 ab cocktail was used to activate cells along with rIL-23 to culture and enrich the MAIT cells. The percentages of each cell population and the mean fluorescence intensity (MFI) were analyzed using Flow Jo software.

RESULTS

MAIT cells were enriched in synovial fluid of PsA (4.29 ± 0.82%) compared to PBMC (1.04 ± 0.71). With stimulation, SFMC MAIT cells produced significantly more IL-17A (32.66 ± 4.01%) compared to that of RA (23.93 ± 2.81%, p < 0.05) and OA (5.02 ± 0.16%, p < 0.05). MAIT cells were predominantly CD8⁺ (>80%). Significant upregulation of IL-23R was noted in synovial fluid MAIT cells of PsA (24.97 ± 2.33%, p < 0.001) and RA (21.93 ± 2.29%, p < 0.001) compared to that of OA (2.13 ± 2.29). This IL-23R was functionally active as evidenced by profound mitotic effect in presence of rIL-23.

CONCLUSION

MAIT cells are poly functional; produce multiple cytokines (IL-17A, IFN-γ, TNF-α). Here, we demonstrated synovial fluid MAIT cells as a major source of IL-17A and majority of MAIT cells were CD8⁺. Functionally active IL-23R on these migrated MAIT cells brings a new dimension. They may not need MR1 associated activation rather lesional IL-23 in the synovium can independently regulate these critical Tc17 CD8⁺ MAIT cells. Thus, these cells likely to be a part of the IL-23/IL-17A cytokine network and play a critical role in the pathogenesis of PsA.

Risk Factors for the Development of Psoriasis

Psoriasis is an immune-mediated genetic skin disease. The underlying pathomechanisms involve complex interaction between the innate and adaptive immune system. T cells interact with dendritic cells, macrophages, and keratinocytes, which can be mediated by their secreted cytokines. In the past decade, biologics targeting tumor necrosis factor-α, interleukin (IL)-23, and IL-17 have been developed and approved for the treatment of psoriasis. These biologics have dramatically changed the treatment and management of psoriasis. In contrast, various triggering factors can elicit the disease in genetically predisposed individuals. Recent studies suggest that the exacerbation of psoriasis can lead to systemic inflammation and cardiovascular comorbidity. In addition, psoriasis may be associated with other auto-inflammatory and auto-immune diseases. In this review, we summarize the risk factors, which can be divided into two groups (namely, extrinsic and intrinsic risk factors), responsible for the onset and exacerbation of psoriasis in order to facilitate its prevention.

Psoriasis: Association of interleukin-17 gene polymorphisms with severity and response to treatment

Psoriasis is a chronic, inflammatory disease with a complex pathogenesis that is not yet fully understood. Although it is a multifactorial disease, the genetic factor has a major role in the pathogenesis of psoriasis. Genome wide association studies have identified over 50 genetic loci associated with psoriasis risk. Beside TNF-α or IL-23, the IL-17 family is a newer group that has proven implications in the pathogenesis of psoriasis. The most important members of the family, with pro-inflammatory qualities, are IL-17A and IL-17F. These interleukins are produced by a varied number of cells, but by far the most important are Th17 cells. Of the patients 20-30% present moderate-to-severe psoriasis, therefore, systemic medication (phototherapy, methotrexate, cyclosporine, acitretin or biologic agents) is mandatory. The necessity of an individualized treatment plan, for each patient, is imperative in order to establish the best strategy for non-responders to classical treatment or to other biologic treatments. The discovery of Th17 pathway improved the treatment and prognosis of psoriasis. Anti-psoriatic agents against IL-17 or its receptors are a novel group of biologic agents; these include ixekizumab, secukinumab and brodalumab. Polymorphisms of IL-17 family have been correlated with the severity and response to treatment in psoriasis, and also with the risk of inflammatory, infectious, autoimmune or neoplastic pathologies. The significant difference in the presence or absence of susceptibility loci in different population is due to genetic background and environmental factors that have a major impact on disease predisposition. In this study, we reviewed the importance and influence of the IL-17 polymorphisms as predictors of response to treatment and severity of the disease.

Adaptive and Innate Immunity in Psoriasis and Other Inflammatory Disorders

Over the past three decades, a considerable body of evidence has highlighted T cells as pivotal culprits in the pathogenesis of psoriasis. This includes the association of psoriasis with certain MHC (HLA) alleles, oligoclonal expansion of T cells in some cases, therapeutic response to T cell-directed immunomodulation, the onset of psoriasis following bone marrow transplantation, or induction of psoriasis-like inflammation by T cells in experimental animals. There is accumulating clinical and experimental evidence suggesting that both autoimmune and autoinflammatory mechanisms lie at the core of the disease. Indeed, some studies suggested antigenic functions of structural proteins, and complexes of self-DNA with cathelicidin (LL37) or melanocytic ADAMTSL5 have been proposed more recently as actual auto-antigens in some cases of psoriasis. These findings are accompanied by various immunoregulatory mechanisms, which we increasingly understand and which connect innate and adaptive immunity. Specific adaptive autoimmune responses, together with our current view of psoriasis as a systemic inflammatory disorder, raise the question of whether psoriasis may have connections to autoimmune or autoinflammatory disorders elsewhere in the body. While such associations have been suspected for many years, compelling mechanistic evidence in support of this notion is still scant. This review sets into context the current knowledge about innate and adaptive immunological processes in psoriasis and other autoimmune or autoinflammatory diseases.

Knockdown of TRAF3IP2 suppresses the expression of VEGFA and the proliferation of keratinocytes and vascular endothelial cells

OBJECTIVE

To investigate the expression level of TRAF3IP2 in psoriasis lesion, and to explore the functional roles of TRAF3IP2 on proliferation, apoptosis, cytokine expression and secretion of both keratinocytes and vascular endothelial cells in vitro.

METHODS

The expression of TRAF3IP2 in skin samples of patients with psoriasis was analyzed by immunohistochemistry and qRT-PCR. To identify the effect of TRAF3IP2 knockdown on HaCaT and HUVEC cells, a plasmid vector expressing siRNA targeting TRAF3IP2 mRNA was designed and transfected into cells with Lipofectamine 2000. The levels of cytokines were identified using the ELISA Kits and qRT-PCR. Furthermore, cell proliferation, cell cycle and apoptosis were examined by using MTT, PI and Annexin V-FITC/7AAD assays, respectively. Furthermore, the expression of apoptosis-related proteins (Cleaved-Caspase 3, Caspase 3 and Bax) were detected by western blotting.

RESULTS

TRAF3IP2 was significantly upregulated in psoriasis lesion. TRAF3IP2 knockdown reduced the expression of vascular endothelial growth factor A (VEGFA) and the release of IL-6, and IL-8, but had no effect on IL-23 in both HaCaT and HUVEC cells. In addition, knockdown of TRAF3IP2 significantly inhibited cell proliferation through blocking the cell cycle in the G2/M phase. Moreover, knockdown of TRAF3IP2 increased the expression of Caspase 3, Cleaved-Caspase 3 and Bax, which was supported by the increased apoptosis of both HaCaT and HUVEC cells.

CONCLUSION

Taken together, these results indicated that TRAF3IP2 might play a contributive role in the pathogenesis of psoriasis and may serve as a new target for the treatment of psoriasis. VEGF related pathways may be involved in the mechanism beneath.

Robust Reference Powered Association Test of Genome-Wide Association Studies

Genome-wide association studies (GWASs) have identified abundant genetic susceptibility loci, GWAS of small sample size are far less from meeting the previous expectations due to low statistical power and false positive results. Effective statistical methods are required to further improve the analyses of massive GWAS data. Here we presented a new statistic (Robust Reference Powered Association Test) to use large public database (gnomad) as reference to reduce concern of potential population stratification. To evaluate the performance of this statistic for various situations, we simulated multiple sets of sample size and frequencies to compute statistical power. Furthermore, we applied our method to several real datasets (psoriasis genome-wide association datasets and schizophrenia genome-wide association dataset) to evaluate the performance. Careful analyses indicated that our newly developed statistic outperformed several previously developed GWAS applications. Importantly, this statistic is more robust than naive merging method in the presence of small control-reference differentiation, therefore likely to detect more association signals.

Psoriasis Pathogenesis and Treatment

Research on psoriasis pathogenesis has largely increased knowledge on skin biology in general. In the past 15 years, breakthroughs in the understanding of the pathogenesis of psoriasis have been translated into targeted and highly effective therapies providing fundamental insights into the pathogenesis of chronic inflammatory diseases with a dominant IL-23/Th17 axis. This review discusses the mechanisms involved in the initiation and development of the disease, as well as the therapeutic options that have arisen from the dissection of the inflammatory psoriatic pathways. Our discussion begins by addressing the inflammatory pathways and key cell types initiating and perpetuating psoriatic inflammation. Next, we describe the role of genetics, associated epigenetic mechanisms, and the interaction of the skin flora in the pathophysiology of psoriasis. Finally, we include a comprehensive review of well-established widely available therapies and novel targeted drugs.

Discover the Potential: Exploring New Frontiers of IL-23 Inhibitors

Affecting up to 11.4% of the population worldwide,1 psoriasis is one of the most common chronic autoinflammatory diseases. It is associated with multiple comorbidities and can have profound negative effects on physical and emotional wellbeing and overall quality of life, making it a serious public health concern. A primary objective of this symposium was to explain the pathogenesis of psoriasis and its relation to the development of novel targeted immune therapies. Psoriasis is characterised by skin and systemic damage consequent to pathogenic cytokine production under the influence of both environmental and genetic factors. Differentiation of Th17 cells from naïve T cells is central to the development of psoriasis, and recently pathogenic models have identified IL-23 as the pathogenic cytokine responsible for promoting Th17 cell proliferation and IL-17 production. Therefore, selective blockade of IL-23 may be instrumental in controlling Th17-mediated inflammation in psoriasis. Another key objective of the symposium was to evaluate key learnings from the latest available clinical trial data on agents targeting the IL-23/Th17 signalling pathway and how these learnings can be harnessed to improve the management of patients with psoriasis. Both IL-17 inhibitors (e.g., ixekizumab and secukinumab) and IL-23 inhibitors (e.g., guselkumab and risankizumab) have demonstrated high efficacy and a good safety profile. Anti-IL-17 agents have faster onset of action and allow the achievement of good response rates very rapidly. Efficacy is better maintained over time with anti-IL-23 agents, including in patients who have stopped and those that then restarted anti-IL-23 therapy after a withdrawal period. Despite the availability of effective treatments, undertreatment in psoriasis is common. This can be attributed to factors such as the heterogeneous nature of psoriasis and relatively large prevalence of addictive behaviours in patients with the condition. When making treatment decisions, it is important to consider these factors as well as patient preferences and expectations, so that treatment can be individualised as much as possible. The symposium concluded with an interactive session, which offered the audience the opportunity to ask questions and discuss relevant issues of interest.

Psoriasis and the TNF/IL23/IL17 axis

The excellent response of psoriasis to anti-TNF-α(TNF)/IL23/IL17A biologics implies a crucial role for the TNF/IL23/IL17 axis in developing psoriasis. In addition to the TNF/IL23/IL17 axis provided by immune cells, current evidence points to an important contribution of TNF, IL23 and IL17C produced from non-hematopoietic keratinocytes. Therefore, crosstalk between immune cells and keratinocytes forms a multilayered feed-forward loop to accelerate the TNF/IL23/IL17A axis. Many biologics have already been licensed or are under clinical trials. Given that the IL-17 signature is more upregulated in the skin than in synovium in psoriatic arthritis, anti-IL-23/IL-17 agents seem to be superior to anti-TNF-α remedies in the treatment of skin lesions. In this review, we summarize recent topics in psoriasis and the TNF/IL23/IL17 axis.