One SNP at a Time: Moving beyond GWAS in Psoriasis

Functional Genomics and Insights into the Pathogenesis and Treatment of Psoriasis

Psoriasis is a lifelong, systemic, immune mediated inflammatory skin condition, affecting 1-3% of the world's population, with an impact on quality of life similar to diseases like cancer or diabetes. Genetics are the single largest risk factor in psoriasis, with Genome-Wide Association (GWAS) studies showing that many psoriasis risk genes lie along the IL-23/Th17 axis. Potential psoriasis risk genes determined through GWAS can be annotated and characterised using functional genomics, allowing the identification of novel drug targets and the repurposing of existing drugs. This review is focused on the IL-23/Th17 axis, providing an insight into key cell types, cytokines, and intracellular signaling pathways involved. This includes examination of currently available biological treatments, time to relapse post drug withdrawal, and rates of primary/secondary drug failure, showing the need for greater understanding of the underlying genetic mechanisms of psoriasis and how they can impact treatment. This could allow for patient stratification towards the treatment most likely to reduce the burden of disease for the longest period possible.

RNA-Based Antipsoriatic Gene Therapy: An Updated Review Focusing on Evidence from Animal Models

Psoriasis presents as a complex genetic skin disorder, characterized by the interaction between infiltrated immune cells and keratinocytes. Substantial progress has been made in understanding the molecular mechanisms of both coding and non-coding genes, which has positively impacted clinical treatment approaches. Despite extensive research into the genetic aspects of psoriasis pathogenesis, fully grasping its epigenetic component remains a challenging endeavor. In response to the pressing demand for innovative treatments to alleviate inflammatory skin disorders, various novel strategies are under consideration. These include gene therapy employing antisense nucleotides, silencing RNA complexes, stem cell therapy, and antibody-based therapy. There is a pressing requirement for a psoriasis-like animal model that replicates human psoriasis to facilitate early preclinical evaluations of these novel treatments. The authors conduct a comprehensive review of various gene therapy in different psoriasis-like animal models utilized in psoriasis research. The animals included in the list underwent skin treatments such as imiquimod application, as well as genetic and biologic injections, and the results of these interventions are detailed. Animal models play a crucial role in translating drug discoveries from the laboratory to clinical practice, and these models aid in improving the reproducibility and clinical applicability of preclinical data. Numerous animal models with characteristics similar to those of human psoriasis have proven to be useful in understanding the development of psoriasis. In this review, the article focuses on RNA-based gene therapy exploration in different types of psoriasis-like animal models to improve the treatment of psoriasis.

Multi-Omics Approach to Improved Diagnosis and Treatment of Atopic Dermatitis and Psoriasis

Psoriasis and atopic dermatitis fall within the category of cutaneous immune-mediated inflammatory diseases (IMIDs). The prevalence of IMIDs is increasing in industrialized societies, influenced by both environmental changes and a genetic predisposition. However, the exact immune factors driving these chronic, progressive diseases are not fully understood. By using multi-omics techniques in cutaneous IMIDs, it is expected to advance the understanding of skin biology, uncover the underlying mechanisms of skin conditions, and potentially devise precise and personalized approaches to diagnosis and treatment. We provide a narrative review of the current knowledge in genomics, epigenomics, and proteomics of atopic dermatitis and psoriasis. A literature search was performed for articles published until 30 November 2023. Although there is still much to uncover, recent evidence has already provided valuable insights, such as proteomic profiles that permit differentiating psoriasis from mycosis fungoides and β-defensin 2 correlation to PASI and its drop due to secukinumab first injection, among others.

Immunosuppression causes dynamic changes in expression QTLs in psoriatic skin

Psoriasis is a chronic, systemic inflammatory condition primarily affecting skin. While the role of the immune compartment (e.g., T cells) is well established, the changes in the skin compartment are more poorly understood. Using longitudinal skin biopsies (n = 375) from the "Psoriasis Treatment with Abatacept and Ustekinumab: A Study of Efficacy"(PAUSE) clinical trial (n = 101), we report 953 expression quantitative trait loci (eQTLs). Of those, 116 eQTLs have effect sizes that were modulated by local skin inflammation (eQTL interactions). By examining these eQTL genes (eGenes), we find that most are expressed in the skin tissue compartment, and a subset overlap with the NRF2 pathway. Indeed, the strongest eQTL interaction signal - rs1491377616-LCE3C - links a psoriasis risk locus with a gene specifically expressed in the epidermis. This eQTL study highlights the potential to use biospecimens from clinical trials to discover in vivo eQTL interactions with therapeutically relevant environmental variables.

Genetic and Epigenetic Mechanisms of Psoriasis

Psoriasis is a disease involving the innate and adaptative components of the immune system, and it is triggered by environmental factors in genetically susceptible individuals. However, its physiopathology is not fully understood yet. Recent technological advances, especially in genome and epigenome-wide studies, have provided a better understanding of the genetic and epigenetic mechanisms to determine the physiopathology of psoriasis and facilitate the development of new drugs. This review intends to summarize the current evidence on genetic and epigenetic mechanisms of psoriasis.

Influence of ABCB1 3435C>T polymorphism on methotrexate safety in patients with psoriasis

Introduction: Methotrexate is a highly effective systemic treatment for moderate to severe psoriasis, but drug toxicity may limit its use. Recent evidence suggests that it is necessary to take into account the individual characteristics of methotrexate pharmacokinetics, which are determined by the presence of polymorphisms of genes encoding methotrexate carrier proteins, to predict the risk of methotrexate-induced toxicity. Goal: To identify associations of ABCB1 rs1045642 polymorphism with methotrexate safety in patients with psoriasis. Materials and methods: The study included 75 patients diagnosed with psoriasis who received methotrexate. Data on adverse drug reactions were collected using a clinically structured questionnaire, complete and biochemical blood tests, and urinalysis. The severity of adverse drug reactions was assessed using visual analog scales and the CTCAE toxicity scale. The severity of gastrointestinal ADR was assessed using the GSRS questionnaire. Genotyping was carried out by real-time PCR. Results: Gastrointestinal toxicity was detected in 38 patients (50.67%). The mean GSRS score was 7.979.18. Analysis of differences in the incidence of adverse drug reactions showed the presence of statistically significant differences in the frequency of adverse drug reactions in the gastrointestinal tract: the toxic effect of methotrexate was more often observed in carriers of the T allele of the ABCB1 rs1045642 polymorphism (3435CT), (CC - 2 (14.3%), TC - 18 (52.9%), TT - 18 (66.7%), p=0.006). Binomial regression demonstrated the presence of a statistically significant effect of the rs1045642 polymorphism of the ABCB1 gene on the incidence of ADR from the gastrointestinal tract: estimation -2.16, OR = 8.64, 95% CI OR: 1.78 - 42.01, p -value = 0.008. Conclusion: An association of ABCB1 rs1045642 polymorphism with the safety of gastrointestinal methotrexate therapy in patients with moderate and severe forms of psoriasis was revealed. The data obtained can be used to personalize the prescription of methotrexate to patients with psoriasis.

Management of Infections in Psoriatic Patients Treated with Systemic Therapies: A Lesson from the Immunopathogenesis of Psoriasis

Modern treatments continue to be developed based on identifying targets within the innate and adaptive immune pathways associated with psoriasis. Whilst there is a sound biologic rationale for increased risk of infection following treatment with immunomodulators, the clinical evidence is confounded by these agents being used in patients affected with several comorbidities. In an era characterized by an ever greater and growing risk of infections, it is necessary to always be updated on this risk. In this mini-review, we will discuss recent updates in psoriasis immunopathogenesis as a rationale for systemic therapy, outline the risk of infections linked to the disease itself and systemic therapy as well, and provide an overview of the prevention and management of infections.

The Impact of Psoriasis and Atopic Dermatitis on Quality of Life: A Literature Research on Biomarkers

Psoriasis (PSO) and Atopic dermatitis (AD) are common inflammatory skin diseases that affect people of all ages globally. They negatively impact the quality of life (QoL) of patients in health-related aspects such as physical, psychological and mental functioning. Here, we conducted a review of studies relating to candidate biomarkers and indicators associated with QoL impairment in PSO and AD. Data research was performed using PUBMED and SCOPUS databases from inception to September 2022. Most of the included studies reported genomic or proteomic biomarkers associated with disease activity and QoL outcomes. Sociodemographic, clinical and therapeutic factors have also been implicated in deterioration of life quality in these patients. The inclusion of clinical characteristics, QoL impairment and co-diagnosis should be considered in drug development programs, since processing biomarkers based on an increased number of features in addition to drug class and disease will intensify the value of the biomarker itself, thereby maximizing the future clinical utility as a stratification tool.

Association between CARD14 gene polymorphisms and psoriasis vulgaris in Hainan Han population based on exon sequencing: A case-control study

Psoriasis is a serious non-communicable, chronic immune-inflammatory mediated disease affecting about 125 million people worldwide. Its effects go beyond skin manifestation. Through genome-wide association studies, the caspase recruitment domain family member 14 (CARD14) gene and other gene variants have been implicated to have an association with Psoriasis, and as we move towards individualized therapy the discovery of single nucleotide polymorphism (SNP) is of great importance. This study aimed to determine whether the CARD14 gene is a susceptible gene for psoriasis vulgaris. In this study, 101 psoriasis patients and 79 healthy controls were subjected to exome sequencing. The CARD14 gene regions upstream and downstream of 1kb were sequenced. SNP-based association analysis and haplotype-based association analysis were performed in SNPs with minimum allele frequency (MAF) greater than 1%. Bioinformatic methods were used to predict the impact of risk loci on gene function. A total of 32 polymorphisms were identified in this study, of which 3 SNPs (1 in exon and 2 in intron) were susceptible to psoriasis (P < .05, OR = 0.19~0.53, 95%CI = 0.05~0.70). Bioinformatics analysis showed that rs144475004 located on the exon led to an amino acid change from aspartate to histidine. On the other hand, results of haplotype-based association analysis showed that 2 haplotypes (CARD14-1 and CARD14-2) were protective haplotypes of the disease (P < .05, OR = 0.18~0.38, 95%CI = 0.05~0.88), the frequencies in healthy controls and patients was 6.96% and 1.49%, respectively. CARD14 gene is associated with susceptibility to psoriasis vulgaris in the Hainan Han population.

The Inflammatory Factor SNP May Serve as a Promising Biomarker for Acitretin to Alleviate Secondary Failure of Response to TNF-a Monoclonal Antibodies in Psoriasis

Psoriasis is a common immune-mediated inflammatory skin disease. Although biological agents have achieved good clinical efficacy in the treatment of moderate-to-severe psoriasis, the phenomenon of secondary non-response (SNR) has been gradually recognized. SNR refers to the gradual decline of efficacy after the patient achieves clinical remission with biological agents such as TNF-α biologics. Acitretin, as an immunomodulatory systemic drug for psoriasis, can improve the SNR to biological agents with good tolerance, but there are still individual differences in efficacy. Single-nucleotide polymorphisms (SNPs) of many related inflammatory cytokines have been shown to be important factors of individual differences in drug response in psoriasis, but there have been few reports on the use of pharmacogenomics to alleviate the SNR to biological agents. This study recruited 43 patients with psoriasis and 24 normal controls to investigate whether SNPs of inflammatory cytokines could be used as biomarkers for acitretin to alleviate SNR to TNF-α biologics in psoriasis, including rs1800795 (IL-6), rs6887695 (IL-12b), rs3212227 (IL-12b), rs10484879 (IL-17a), rs4819554 (IL-17ra), rs763780 (IL-17F), rs11209032 (IL23R), rs11209026 (IL23R), and rs2201841 (IL23R). The study also analyzed the correlation between the abovementioned SNPs and the efficacy of acitretin-only patients so as to understand whether the improvement is attributable to the intervention of acitretin on SNR or a simple response of acitretin. We found that in patients with homozygous AA (χ2 = 6.577, p = 0.02) at the SNP rs112009032 (IL-23R), acitretin could improve the SNR to TNFα monoclonal antibody. Patients with the genotype of TG (χ2 = 6.124, p = 0.035) at rs3212227 (IL-12B) were more sensitive to using acitretin in the treatment of psoriasis. Rs3212227 (χ2 = 7.664, p = 0.022) was also associated with the susceptibility to psoriasis. The study might provide a clinical decision reference for personalized treatment of secondary loss of response to psoriasis biologics.

Protective association exhibited by a single nucleotide polymorphism of the IFIH1 gene in patients with psoriasis: A case-control study

Introduction

Psoriasis is a chronic inflammatory dermatosis, a with variable clinical presentation and whose multifactorial etiology carries an essential genetic component. Multiple genetic variations associated with psoriasis have been described around the world. However, these variants are unknown among the Colombian population. This study aimed to evaluate the single nucleotide polymorphism rs10930046 (His460Arg) in the IFIH1 gene and its ssociation with the development of psoriasis in a Colombian population.

Methods

An observational, unmatched, case-control study was performed, including 51 patients with psoriasis and 151 population controls, all with self-reported Paisa ancestry (from the Antioquia region). All individuals were genotyped for the single nucleotide polymorphism rs10930046 (His460Arg) in the IFIH1 gene, and its association with psoriasis was pursued. Both groups were demographically characterized, and cases were also assessed for clinical variables.

Results

Through the allelic association analysis, cases were found to have a lower frequency of the single nucleotide polymorphism rs10930046 (His460Arg) in the IFIH1 gene than controls; 5% versus 22.67%, respectively. There were no significant differences in age or sex. We also found that psoriasis vulgaris was the most common variant (78%), that about half of the cases had nail psoriasis (56%), 19.6% had psoriatic arthritis, and that 45% had some comorbidity.

Conclusions

The results obtained from this study confirm that carriers of the single nucleotide polymorphism rs10930046 (His460Arg) in the IFIH1 gene have a decreased risk of developing psoriasis.

A transcriptome-wide association study identifies novel susceptibility genes for psoriasis

Although more than 80 psoriasis genetic risk loci have been reported through genome-wide association studies (GWASs), the genetic mechanism of psoriasis remains unclear. To identify novel candidate genes associated with psoriasis and reveal the potential effects of genetic factors in the development of psoriasis, we conducted a transcriptome-wide association study (TWAS) based on summary statistics from GWAS of psoriasis (5175 cases and 447 089 controls) and gene expression levels from six tissues datasets (blood and skin). We identified 11 conditionally independent genes for psoriasis after Bonferroni corrections, such as the most significant genes UBLCP1 (PYFS = 2.98 × 10-16), and LCE3C (PSNSE = 9.72 × 10-12, PSSE = 6.24 × 10-12). The omnibus test identified additional 5 genes associated with psoriasis via the joint association model from multiple reference tissues. Among the 16 identified genes, 5 genes (CTSW, E1F1AD, KLRC3, FIBP, and EFEMP2) were regarded as novel genes for psoriasis. We evaluated the 16 candidate genes by querying public databases and identified 11 differentially expressed genes and 8 genes proved by the knockout mice models. Through GO enrichment analyses, we found that TWAS genes were enriched in the known GO terms associated with skin development, such as cornified envelope (P = 4.80 × 10-8) and peptide cross-linking (P = 1.50 × 10-7). Taken together, our results detected multiple novel candidate genes for psoriasis, providing clues for understanding the genetic mechanism of psoriasis.

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 role of interleukin-17 in asthma: a protective response?

While there now exist effective treatments for type 2 high, eosinophilic asthma, there are no specific therapies for 40–50% of people with asthma with other phenotypes, which result from poorly understood underlying pathological mechanisms. One such pathology is neutrophilic inflammation, which has been associated with interleukin (IL)-17 family cytokines. Human genetic studies identified IL-17 polymorphisms associated with asthma; in murine models of allergic airways disease, IL-17A contributes to airway hyperresponsiveness, and in humans, elevated airway IL-17A levels are repeatedly observed in severe asthma. However, the directionality of this association is unknown, and the assumption that IL-17 cytokines drive disease pathology remains speculative. Here, we explore the evidence underlying the relationship between IL-17 and asthma, we review lessons learned from investigating IL-17 in other inflammatory diseases, and discuss the possibility that IL-17 may even be protective in asthma rather than pathogenic. We also critically examine the newly proposed paradigm of a reciprocal relationship between type 2 and type 17 airways inflammation. In summary, we suggest an association between IL-17 and asthma, but research is needed examining the diverse functions of these cytokines, their longitudinal stability, their response to clinical interventions, and for mechanistic studies determining whether they are protective or pathogenic.

IL-17 cytokines have been implicated in neutrophilic asthma by genetic, murine and human data. Here, previous studies are critiqued and the assumption their dominant role is pathogenic rather than protective of airway epithelial barrier integrity is challenged.http://bit.ly/3axB4Zs

Association of rs610604 in TNFAIP3 and rs17728338 in TNIP1 gene polymorphisms with psoriasis susceptibility: a meta-analysis of case-control studies

BACKGROUND

To date, the fundamental pathophysiology underlying the occurrence and progression of psoriasis are still unanswered questions. Genome-wide association surveys have revealed that TNFAIP3 and TNIP1 were key biomarkers for psoriasis. Here, we intended to conduct a survey on the association between TNFAIP3 and TNIP1 gene polymorphisms and psoriasis risk.

METHODS

A comprehensive search of four online databases-China National Knowledge Infrastructure (CNKI), PubMed, Embase, and Cochrane Library was undertaken up to August 25, 2019. We chose allele genetic model to deal with the original data. Newcastle-Ottawa scale (NOS) was used to evaluate the risk bias of each study. The RevMan 5.3 software was used to calculate the combined odds ratio and 95% confidence interval.

RESULTS

In total, we included 13 case-control studies consist of 13,908 psoriasis patients and 20,051 controls in this work. Our results demonstrated that rs610604 in TNFAIP3 polymorphism was significantly associated with psoriasis risk using random-effect model (G vs. T, OR = 1.19, 95% CI: 1.09-1.31, P = 0.0002), and a significant association between rs17728338 in TNIP1 polymorphism and psoriasis vulnerability using fixed-effect model (A vs. G, OR = 1.69, 95% CI:1.58-1.80, P < 0.00001).

CONCLUSIONS

Our findings indicated that rs610604 in TNFAIP3 and rs17728338 in TNIP1 gene polymorphisms were associated with psoriasis susceptibility.

Mapping DNA interaction landscapes in psoriasis susceptibility loci highlights KLF4 as a target gene in 9q31

BACKGROUND

Genome-wide association studies (GWAS) have uncovered many genetic risk loci for psoriasis, yet many remain uncharacterised in terms of the causal gene and their biological mechanism in disease. This is largely a result of the findings that over 90% of GWAS variants map outside of protein-coding DNA and instead are enriched in cell type- and stimulation-specific gene regulatory regions.

RESULTS

Here, we use a disease-focused Capture Hi-C (CHi-C) experiment to link psoriasis-associated variants with their target genes in psoriasis-relevant cell lines (HaCaT keratinocytes and My-La CD8+ T cells). We confirm previously assigned genes, suggest novel candidates and provide evidence for complexity at psoriasis GWAS loci. For one locus, uniquely, we combine further epigenomic evidence to demonstrate how a psoriasis-associated region forms a functional interaction with the distant (> 500 kb) KLF4 gene. This interaction occurs between the gene and active enhancers in HaCaT cells, but not in My-La cells. We go on to investigate this long-distance interaction further with Cas9 fusion protein-mediated chromatin modification (CRISPR activation) coupled with RNA-seq, demonstrating how activation of the psoriasis-associated enhancer upregulates KLF4 and its downstream targets, relevant to skin cells and apoptosis.

CONCLUSIONS

This approach utilises multiple functional genomic techniques to follow up GWAS-associated variants implicating relevant cell types and causal genes in each locus; these are vital next steps for the translation of genetic findings into clinical benefit.

Intracellular Insulin-like growth factor binding protein 2 (IGFBP2) contributes to the senescence of keratinocytes in psoriasis by stabilizing cytoplasmic p21

Psoriasis is a chronic Th1/Th17 lymphocytes-mediated inflammatory skin disease, in which epidermal keratinocytes exhibit a peculiar senescent state, resistance to apoptosis and the acquisition of senescence-associated secretory phenotype (SASP). SASP consists of the release of soluble factors, including IGFBPs, that exert extracellular and intracellular functions in IGF-dependent or independent manner.In this report, we investigated the expression and function of IGFBP2 in senescent keratinocytes isolated from the skin of patients with plaque psoriasis. We found that IGFBP2 is aberrantly expressed and released by these cells in vivo, as well as in vitro in keratinocyte cultures undergoing progressive senescence, and it associates with the cyclin-dependent kinase inhibitors p21 and p16 expression. For the first time, we provide evidence for a dual action of IGFBP2 in psoriatic keratinocytes during growth and senescence processes. While extracellular IGFBP2 counter-regulates IGF-induced keratinocyte hyper-proliferation, intracellular IGFBP2 inhibits apoptosis by interacting with p21 and protecting it from ubiquitin-dependent degradation. Indeed, we found that cytoplasmic p21 sustains anti-apoptotic processes, by inhibiting pro-caspase 3 cleavage and JNK phosphorylation in senescent psoriatic keratinocytes. As a consequence, abrogation of p21, as well as that of IGFBP2, found to stabilize cytoplasmic p21 levels, lead to the restoration of apoptosis mechanisms in psoriatic keratinocytes, commonly observed in healthy cells.

A New Risk Polymorphism rs10403848 of CARD8 Significantly Associated with Psoriasis Vulgaris in Northeastern China

Caspase recruitment domain family member 8 (CARD8) is an adaptor molecule that negatively regulates nuclear factor-κB (NF-κB) activation, interleukin (IL)-1β secretion, and apoptosis. These play important roles in the pathogenesis of psoriasis. Genetic variants of CARD8 have been associated with an increased risk of several inflammatory diseases and psoriasis in Europe. However, nothing is known about the association of the polymorphisms of CARD8 and psoriasis vulgaris (PsV) in the Han population of northeastern China. To investigate the potential association between them, we designed a case-control study to genotype four selected single nucleotide polymorphisms (SNPs) using the improved multiplex ligation reaction (iMLDR) method. Model-based single SNP frequentist-test and haplotype association studies were performed to assess the association between SNPs and PsV. The results showed that the intron SNP rs10403848 was significantly associated with PsV (additive model p=0.0418, p'=0.0411, and statistical power 0.1902; heterozygous model p=0.0418, p'=0.0164, and statistical power 0.9406). A potential risk locus of nonsynonymous SNP rs2043211 found in the European population did not show a significant association in our study. We found that the polymorphism rs10403848 in CARD8 is significantly associated with PsV risk in the Han population of northeastern China. CARD8 may be involved in PsV in this population, as in the European population, but a different genetic process should be considered for the heterogeneity of risk loci.

The role of ceramides in skin homeostasis and inflammatory skin diseases

Ceramides, members of sphingolipid family, are not only the building blocks of epidermal barrier structure, but also bioactive metabolites involved in epidermal self-renewal and immune regulation. Hence, abnormal ceramide expression profile is recognized to defect extracellular lipid organization, disturb epidermal self-renewal, exacerbate skin immune response and actively participate in progression of several inflammatory dermatoses, exemplifying by psoriasis and atopic dermatitis. Here, we discuss recent advances in understanding skin ceramides and their regulatory roles in skin homeostasis and pathogenic roles of altered ceramide metabolism in inflammatory skin diseases. These insights provide new opportunities for therapeutic intervention in inflammatory dermatoses.

Psoriatic arthritis

Psoriasis is a multisystemic, inflammatory skin condition that can affect many areas of the body, but most commonly the extensor surfaces of the elbows and knees, and sometimes the intergluteal and umbilical area. It has a prevalence of 2–4% in western adults, and 20­–30% of psoriasis patients will develop psoriatic arthritis (PsA). PsA is an inflammatory musculoskeletal disease associated with cutaneous psoriasis. It affects men and women almost equally with a peak age at onset of 40 and 50 years. It is a diverse disease that affects multiple organ systems includes peripheral and axial joints, entheses, skin, and nails. PsA is associated with comorbidities such as osteoporosis, uveitis, subclinical bowel inflammation, and cardiovascular disease. Given this heterogeneity, its diagnosis has been difficult. Here we present an updated review of its classification criteria CASPAR (classification criteria for PsA), use of screening tools to aid in early diagnosis, recent findings on pathogenesis, and new therapeutic approaches including new biologic medications.

Immune Control by TRAF6-Mediated Pathways of Epithelial Cells in the EIME (Epithelial Immune Microenvironment)

In the protective responses of epithelial tissues, not only immune cells but also non-immune cells directly respond to external agents. Epithelial cells can be involved in the organization of immune responses through two phases. First, the exogenous harmful agents trigger the primary responses of the epithelial cells leading to various types of immune cell activation. Second, cytokines produced by the immune cells that are activated directly by the external agents and indirectly by the epithelial cell products elicit the secondary responses giving rise to further propagation of immune responses. TRAF6 is a ubiquitin E3 ligase, which intermediates between various types of receptors for exogenous agents or endogenous mediators and activation of subsequent transcriptional responses via NF-kappaB and MAPK pathways. TRAF6 ubiquitously participates in many protective responses in immune and non-immune cells. Particularly, epithelial TRAF6 has an essential role in the primary and secondary responses via driving type 17 response in psoriatic inflammation of the skin. Consistently, many psoriasis susceptibility genes encode the TRAF6 signaling players, such as ACT1 (TRAF3IP2), A20 (TNFAIP3), ABIN1 (TNIP1), IL-36Ra (IL36RN), IkappaBzeta (NFKBIZ), and CARD14. Herein, we describe the principal functions of TRAF6, especially in terms of positive and regulatory immune controls by interaction between immune cells and epithelial cells. In addition, we discuss how TRAF6 in the epithelial cells can organize the differentiation of immune responses and drive inflammatory loops in the epithelial immune microenvironment, which is termed EIME.

The Potential Benefits of Certolizumab Pegol in Patients with Concurrent Psoriatic Arthritis and Chronic Plaque Psoriasis: A Case Series and Review of the Literature

INTRODUCTION

We review the literature evaluating certolizumab in psoriasis and report our experience of treatment outcomes in a joint dermatology and rheumatology clinic.

METHODS

Patients with concomitant psoriatic arthritis (PsA) and psoriasis who had been commenced on certolizumab were included within our retrospective review. Data was collected for patient demographics, Patient Area and Severity Index (PASI), Dermatology Life Quality Index (DLQI) and previous treatments. The literature was systematically searched using Pubmed and Scopus.

RESULTS

Very recent results from the CIMPASI-1 and CIMPASI-2 studies have demonstrated the high efficacy of certolizumab in the treatment of psoriasis at both week 16 and 48. Pooled results from these studies showed a PASI75 at week 16 and week 48 of 82% and 83.6% respectively, in the certolizumab 400 mg group. In our cohort of eight patients (two female; six male; median age 49 and mean PASI of 20.8) all had failed at least two systemic non-biologic agents. Objective improvements were observed in seven patients, with five achieving PASI90 and two demonstrating either PASI75 or PASI50.

CONCLUSION

Certolizumab is efficacious in both psoriasis and PsA, including in patients who are biologic failures, and could be considered as an alternative treatment modality.

Association of rs2910164 polymorphism in MiR-146a gene with psoriasis susceptibility: A meta-analysis

The rs2910164 single nucleotide polymorphism (SNP) in miR-146a has been implicated in the etiology of psoriasis in different relevant studies with contradictory conclusions and limited sample size. Therefore, the aim of this study was to undertake a systematic review and meta-analysis to estimate the association between rs2910164 SNP and psoriasis. We searched the databases of PubMed, EMBASE, Web of Science, WanFang, and Chinese National Knowledge Infrastructure (CNKI) to identify relevant literatures published before July 15, 2018. Four case-control studies including 2212 cases and 2274 healthy controls from 4 different countries met the predetermined criteria. The effect size was pooled by odds ratios (ORs) and 95% confidence intervals (95%CIs). Recessive model (CC vs CG+GG) was confirmed to be the optimal model. The results indicated that rs2910164 SNP was significantly associated with psoriasis (OR = 0.74, 95%CI 0.60-0.91, P = .004), and individuals with CC-genotype were predisposed to have decreased risk of psoriasis.

Multi-omics integration reveals molecular networks and regulators of psoriasis

BACKGROUND

Psoriasis is a complex multi-factorial disease, involving both genetic susceptibilities and environmental triggers. Genome-wide association studies (GWAS) and epigenome-wide association studies (EWAS) have been carried out to identify genetic and epigenetic variants that are associated with psoriasis. However, these loci cannot fully explain the disease pathogenesis.

METHODS

To achieve a comprehensive mechanistic understanding of psoriasis, we conducted a systems biology study, integrating multi-omics datasets including GWAS, EWAS, tissue-specific transcriptome, expression quantitative trait loci (eQTLs), gene networks, and biological pathways to identify the key genes, processes, and networks that are genetically and epigenetically associated with psoriasis risk.

RESULTS

This integrative genomics study identified both well-characterized (e.g., the IL17 pathway in both GWAS and EWAS) and novel biological processes (e.g., the branched chain amino acid catabolism process in GWAS and the platelet and coagulation pathway in EWAS) involved in psoriasis. Finally, by utilizing tissue-specific gene regulatory networks, we unraveled the interactions among the psoriasis-associated genes and pathways in a tissue-specific manner and detected potential key regulatory genes in the psoriasis networks.

CONCLUSIONS

The integration and convergence of multi-omics signals provide deeper and comprehensive insights into the biological mechanisms associated with psoriasis susceptibility.

The epithelial immune microenvironment (EIME) in atopic dermatitis and psoriasis

The skin provides both a physical barrier and an immunologic barrier to external threats. The protective machinery of the skin has evolved to provide situation-specific responses to eliminate pathogens and to provide protection against physical dangers. Dysregulation of this machinery can give rise to the initiation and propagation of inflammatory loops in the epithelial microenvironment that result in inflammatory skin diseases in susceptible people. A defective barrier and microbial dysbiosis drive an interleukin 4 (IL-4) loop that underlies atopic dermatitis, while in psoriasis, disordered keratinocyte signaling and predisposition to type 17 responses drive a pathogenic IL-17 loop. Here we discuss the pathogenesis of atopic dermatitis and psoriasis in terms of the epithelial immune microenvironment-the microbiota, keratinocytes and sensory nerves-and the resulting inflammatory loops.

Discovering Genetic Factors for psoriasis through exhaustively searching for significant second order SNP-SNP interactions

In this paper, we aim at discovering genetic factors of psoriasis through searching for statistically significant SNP-SNP interactions exhaustively from two real psoriasis genome-wide association study datasets (phs000019.v1.p1 and phs000982.v1.p1) downloaded from the database of Genotypes and Phenotypes. To deal with the enormous search space, our search algorithm is accelerated with eight biological plausible interaction patterns and a pre-computed look-up table. After our search, we have discovered several SNPs having a stronger association to psoriasis when they are in combination with another SNP and these combinations may be non-linear interactions. Among the top 20 SNP-SNP interactions being found in terms of pairwise p-value and improvement metric value, we have discovered 27 novel potential psoriasis-associated SNPs where most of them are reported to be eQTLs of a number of known psoriasis-associated genes. On the other hand, we have inferred a gene network after selecting the top 10000 SNP-SNP interactions in terms of improvement metric value and we have discovered a novel long distance interaction between XXbac-BPG154L12.4 and RNU6-283P which is not a long distance haplotype and may be a new discovery. Finally, our experiments with the synthetic datasets have shown that our pre-computed look-up table technique can significantly speed up the search process.

Interaction of Psoriasis and Bullous Diseases

Patients with psoriasis are frequently complicated with autoimmune bullous diseases, especially, pemphigoid diseases. It has been known that one-third cases of anti-laminin gamma1 pemphigoid, formerly anti-p200 pemphigoid, are associated with psoriasis whereas bullous pemphigoid is the most frequently associated bullous disease in psoriasis cases regardless of the lack of detectable levels of the accompanying anti-laminin gamma1 autoantibodies. Despite several suggestions, however, the definitive reason of the striking association of psoriasis and these autoimmune bullous diseases remains elusive. In this review, we look over the epidemiological evidence of the association of psoriasis and autoimmune bullous diseases and the information of genetic susceptibilities of each disease, and discuss the possible mechanisms of their complication with reference to the recent understandings of each pathogenesis.

The IL-17 Family of Cytokines in Psoriasis: IL-17A and Beyond

Psoriasis is a frequent chronic inflammatory skin disease, nowadays considered a major global health problem. Several new drugs, targeting the IL-23/IL-17A pathway, have been recently licensed or are in clinical development. These therapies represent a major improvement of the way in which psoriasis is managed, since they show an unprecedented efficacy on skin symptoms of psoriasis. This has been made possible, thanks to an increasingly more accurate pathogenic view of psoriasis. Today, the belief that Th17 cells mediate psoriasis is moving to the concept of psoriasis as an IL-17A-driven disease. New questions arise at the horizon, given that IL-17A is part of a newly described family of cytokines, which has five distinct homologous: IL-17B, IL-17C, IL-17D, IL-17E, also known as IL-25 and IL-17F. IL-17 family cytokines elicit similar effects in target cells, but simultaneously trigger different and sometimes opposite functions in a tissue-specific manner. This is complicated by the fact that IL-17 cytokines show a high capacity of synergisms with other inflammatory stimuli. In this review, we will summarize the current knowledge around the cytokines belonging to the IL-17 family in relation to skin inflammation in general and psoriasis in particular, and discuss possible clinical implications. A comprehensive understanding of the different roles played by the IL-17 cytokines is crucial to appreciate current and developing therapies and to allow an effective pathogenesis- and mechanisms-driven drug design.

Association of NLRP1 and NLRP3 Polymorphisms with Psoriasis Vulgaris Risk in the Chinese Han Population

Aim

To clarify the association between the single nucleotide polymorphisms (SNPs) in the NLRP1 and NLRP3 and Psoriasis Vulgaris (PsV) in the Chinese Han population.

Methods

We genotyped eight SNPs, four from NLRP1 (rs8079034, rs11651270, rs11657747, and rs878329) and NLRP3 (rs7512998, rs3806265, rs10754557, and rs10733113) each in 540 patients with PsV and 612 healthy controls in the Chinese Han population using an improved multiplexed ligation detection reaction (iMLDR) method. The genotype and haplotype frequencies were analyzed using a case-control study design.

Results

We identified two SNPs, rs3806265 and rs10754557, in NLRP3 that were significantly associated with PsV. The genotype distribution of the rs3806265 SNP was significantly different between cases and controls (p = 0.0451; OR = 0.791; 95% CI = 0.627–0.998). In the recessive model, the genotype distribution of the rs10754557 SNP was significantly different between cases and controls (p = 0.0344; OR = 1.277; 95% CI = 0.987–1.652). The haplotype analysis of rs3806265 and rs10754557 also presented a significant association of TA haplotype with PsV (χ² = 4.529; p = 0.033).

Conclusion

NLRP3 may play a role in PsV susceptibility in the Chinese Han population.

Genetic and experimental evidence for the involvement of the CD6 lymphocyte receptor in psoriasis

Psoriasis is a chronic inflammatory skin disease with a strong genetic background and is triggered by environmental factors. Available evidence supports CD6, a lymphocyte surface receptor mostly expressed by T cells, as a putative target in autoimmunity. Accordingly, a humanized anti-CD6 antibody has been assayed for the treatment of certain autoimmune disorders, including psoriasis. Here, we present novel evidence in mice and humans for a direct involvement of CD6 in psoriasis pathophysiology. First, an attenuated form of imiquimod-induced psoriasis-like skin inflammation was demonstrated in CD6-deficient mice, as deduced from lower epidermal thickness and local reduced production of pro-inflammatory cytokines, namely, interleukin-17A. Thus, isolated CD4⁺CD62L⁺ T cells from CD6-deficient mice displayed decreased in vitro T-helper type 17 polarization. Second, a statistically significant association between CD6 single-nucleotide polymorphisms (rs17824933, rs11230563 and rs12360861) and more severe forms of psoriasis was demonstrated in a cohort of 304 patients at three public hospitals from the metropolitan area of Barcelona. Taken together, these results provide new supportive evidence of the contribution of the CD6 lymphocyte receptor in psoriasis at both experimental and clinical levels.

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

BACKGROUND

Large cohort-based genetic association studies have been established over a decade. However, for certain diseases, different results with respect to the genome-wide association study level have been obtained among studies, even for those conducted within the same ethnic groups. We hypothesized that onset age-based sample variables might have a great impact on the results.

METHODS

In the present study, we divided psoriasis patients into several subgroups according to the onset age bracket. We conducted genetic association analysis in the major histocompatibility complex (MHC) region of each patient subgroup with shared control subjects.

RESULTS

We found decreases in the numbers of susceptible variants in each subgroup analysis as the onset age increased in the longitudinal analysis. Meanwhile, the pairwise analysis showed that younger patients exhibited greater numbers of genetic risks in the MHC region compared to elder patients, regardless of whether the cut-off values were defined as 20 or 30 years old. Similar results were also found among 11-20-, 21-30- and 31-40-year-old groups. Furthermore, when combining the results of both the stepwise regression analysis and the HLA-C*06:02 conditioning analysis, different variants were found to be independently associated with each psoriasis subgroup.

CONCLUSIONS

Onset age-based sample variables influence the results of genetic association studies, at least in MHC region-based genetic analysis. We suggest that caution is required when selecting samples for genetic association studies to prevent confounders that might be a result of onset age.

A new panel of SNPs to assess thyroid carcinoma risk: a pilot study in a Brazilian admixture population

BACKGROUND

Thyroid cancer is a common malignant disease of the endocrine system with increasing incidence rates over the last few decades. In this study, we sought to analyze the possible association of 45 single nucleotide polymorphisms (SNPs) with thyroid cancer in a population from Rio Grande do Norte, Brazil.

METHODS

Based on histological analysis by a pathologist, 80 normal thyroid specimens of tissue adjacent to thyroid tumors were obtained from the biobank at the Laboratory of Pathology of Liga Norte Riograndense Contra o Câncer, Natal, RN. Patient samples were then genotyped using the MassARRAY platform (Sequenon, Inc) followed by statistical analysis employing the SNPassoc package in R program. The genotypic frequencies of all 45 SNPs obtained from the International HapMap Project database and based on data from the ancestral populations of European and African origin were used to compose the control study group.

RESULTS

In our study, the following 9 SNPs showed significant differences in their frequency when comparing the study and control groups: rs3744962, rs258107, rs1461855, rs4075022, rs9943744, rs4075570, rs2356508, rs17485896, and rs2651339. Furthermore, the SNPs rs374492 C/T and rs258107 C/T were associated with a relative risk for thyroid carcinoma of 3.78 (p = 6.27 × 10e^-5) and 2.91 (p = 8.27 × 10e^-5), respectively, after Bonferroni's correction for multiple comparisons.

CONCLUSIONS

These nine polymorphisms could be potential biomarkers of predisposition to thyroid carcinoma in the population from Rio Grande do Norte. However, complementary studies including a control group with samples obtained from healthy subjects in Rio Grande do Norte state, should be conducted to confirm these results.

Autoimmune aspects of psoriasis: Heritability and autoantigens

Chronic immune-mediated disorders (IMDs) constitute a major health burden. Understanding IMD pathogenesis is facing two major constraints: Missing heritability explaining familial clustering, and missing autoantigens. Pinpointing IMD risk genes and autoimmune targets, however, is of fundamental importance for developing novel causal therapies. The strongest association of all IMDs is seen with human leukocyte antigen (HLA) alleles. Using psoriasis as an IMD model this article reviews the pathogenic role HLA molecules may have within the polygenic predisposition of IMDs. It concludes that disease-associated HLA alleles account for both missing heritability and autoimmune mechanisms by facilitating tissue-specific autoimmune responses through autoantigen presentation.

Opportunities and challenges of whole-genome and -exome sequencing

Recent advances in the development of sequencing technologies provide researchers with unprecedented possibilities for genetic analyses. In this review, we will discuss the history of genetic studies and the progress driven by next-generation sequencing (NGS), using complex inflammatory bowel diseases as an example. We focus on the opportunities, but also challenges that researchers are facing when working with NGS data to unravel the genetic causes underlying diseases.

Recent Highlights in Psoriasis Research

This article highlights recent advances in the immunology, epidemiology, and genetics/genomics of psoriasis. Advances sometimes generate more questions, and this article makes an attempt to point out where controversies might exist in the literature. Many of the articles mentioned were published in the Journal of Investigative Dermatology, but many articles from the broader scientific literature are also cited, to provide context and to add further validity for some of these key findings. Among the themes we explore are the identification of antigens in psoriasis, the co-morbidities of psoriasis, and novel integrative approaches to genome-wide association studies.

Recent advances in understanding and managing psoriatic arthritis

This article reviews recent advances in psoriatic arthritis (PsA) over the past several years with emphasis on early diagnosis, better understanding of pathogenesis, and new therapeutic approaches. Early diagnosis is important, since people who present late do not fare as well. There are a number of clinical, laboratory, and ultrasound features that can help identify patients destined to develop PsA, and several screening tools have been developed. It is recognized that genetic and epigenetic factors, as well as T cells and cytokines, play a role in the pathogenesis of PsA, and several targets have been identified for therapeutic interventions. New therapies have been developed and tested in PsA and have been found to be highly effective for both skin and joint manifestations of the disease. The expectation is that, in the future, PsA patients will be treated early and more aggressively and that there will not be significant progression of joint damage. Moreover, with effective treatment of the skin and joint disease and management of risk factors for the comorbidities, we can expect to reduce their occurrence and further reduce the excess mortality and reduced quality of life and function in these patients.

MicroRNA-146a suppresses IL-17-mediated skin inflammation and is genetically associated with psoriasis

BACKGROUND

Psoriasis is an immune-mediated inflammatory skin disease with a strong genetic background in which activation of IL-17 signaling is central in the pathogenesis. Little has been known about the role of noncoding RNAs, including microRNAs (miRNAs), in predisposition to the disease.

OBJECTIVE

We sought to investigate the genetic association of single nucleotide polymorphisms in microRNA-146a (miR-146a) to psoriasis and to explore its function in the initiation and resolution of the disease.

METHODS

Analysis of the genetic association of miR-146a rs2910164 and psoriasis was carried out on 1546 patients with psoriasis and 1526 control subjects. The role of miR-146a in patients with psoriasis was assessed by using miR-146a^-/- mice in conjunction with the imiquimod-induced mouse model of psoriasis. The severity of psoriasis-like skin inflammation was evaluated at morphologic, histologic, and molecular levels. miR-146a was ectopically overexpressed and inhibited in keratinocytes treated with IL-17. Synthetic miR-146a was injected intradermally into mice.

RESULTS

Here we report protective association of a functional polymorphism in the miR-146a precursor (rs2910164). Genetic deficiency in miR-146a leads to earlier onset and exacerbated pathology of skin inflammation, with increased expression of IL-17-induced keratinocyte-derived inflammatory mediators, epidermal hyperproliferation, and increased neutrophil infiltration. Moreover, miR-146a-deficient mice do not resolve inflammation after discontinuation of imiquimod challenge. The overexpression of miR-146a suppressed, whereas its inhibition enhanced, IL-17-driven inflammation in keratinocytes. Functionally, miR-146a impairs the neutrophil chemoattractant capacity of keratinocytes. Finally, delivery of miR-146a mimics into the skin leads to amelioration of psoriasiform skin inflammation, decreased epidermal proliferation, and neutrophil infiltration.

CONCLUSIONS

Our results define a crucial role for miR-146a in modulating IL-17-driven inflammation in the skin.