The Spectrum of Mild to Severe Psoriasis Vulgaris Is Defined by a Common Activation of IL-17 Pathway Genes, but with Key Differences in Immune Regulatory Genes

The causal association between psoriasis and 32 types of cancer: a mendelian randomization study

BACKGROUND

Psoriasis is a systemic immune disease associated with the development of various cancers. However, the causal nature of this association remains unclear. This study aims to systematically investigate the potential causal relationship between psoriasis and 32 types of cancer.

METHODS

We utilized data from two large genomic databases, the UK Biobank and FinnGen, to extract GWAS summary statistics for 32 cancer types as outcomes and psoriasis-related data as exposures. Mendelian randomization (MR) analysis was performed to assess the causal effects of psoriasis on cancer risk. Sensitivity analyses, including heterogeneity and horizontal pleiotropy tests, were conducted to ensure robustness. Additionally, meta-analysis and FDR correction were applied to enhance the reliability of the results.

RESULTS

Our findings revealed significant causal relationships between psoriasis and four cancer types: Psoriasis was associated with an increased risk of laryngeal cancer (OR = 1.15, 95% CI: 1.05-1.26). Psoriasis exhibited a protective effect against oral cavity and pharyngeal cancer (OR: 0.91; 95% CI: 0.86-0.97), prostate cancer (OR: 0.97; 95% CI: 0.95-0.99), and malignant non-melanoma cancer (OR: 0.89; 95% CI: 0.82-0.96).

CONCLUSION

Psoriasis may exert bidirectional effects on the development of specific cancers through distinct mechanisms. Specifically, psoriasis may increase the risk of laryngeal cancer while reducing the risk of oral cavity and pharyngeal cancer, prostate cancer, and malignant non-melanoma cancer. These findings provide new insights into the causal relationship between psoriasis and cancer and could inform prevention and treatment strategies for these diseases.

Integrative Analysis of Arachidonic Acid Metabolism in the Pathogenesis and Immune Dysregulation of Psoriasis

Background

Psoriasis is a chronic inflammatory skin disorder with complex molecular mechanisms. While previous studies have demonstrated altered levels of arachidonic acid and its metabolites in psoriatic lesions, the specific roles of arachidonic acid metabolism (AAM) genes in the molecular pathogenesis and immune dysregulation of psoriasis remain poorly understood. This study aimed to investigate the role of AAM genes in the pathogenesis and immune dysregulation of psoriasis using an integrative bioinformatics approach.

Methods

Gene expression data from psoriasis patients and healthy controls were obtained from the Gene Expression Omnibus database and analyzed. Differentially expressed genes were identified, and functional enrichment analyses were performed. Weighted gene co-expression network analysis (WGCNA) and machine learning techniques were employed to identify psoriasis associated AAM genes. Single-sample gene set enrichment analysis (ssGSEA) and immune cell composition analysis were conducted to explore functional implications. Transcription factor prediction analysis was performed to identify potential regulators of key AAM genes.

Results

Differential expression analysis revealed 469 dysregulated genes in psoriasis, with functional enrichment highlighting the involvement of epidermis development, immune response, and inflammation. WGCNA and machine learning approaches identified ABCC1, PLA2G3, CYP2J2, and GPX2 as key AAM genes. ssGSEA showed elevated inflammation and immune response in psoriasis, with key AAM genes correlating with specific pathways. Immune cell composition analysis revealed increased infiltration of inflammatory cells in psoriatic skin. Transcription factor prediction analysis identified shared transcription factors for the key AAM genes, suggesting coordinated regulation of their expression in psoriasis.

Conclusion

This integrative analysis identified key AAM genes associated with psoriasis pathogenesis and immune dysregulation, providing novel insights into the molecular basis of psoriasis. The findings highlight potential therapeutic targets and biomarkers, which could lead to improved diagnosis and treatment strategies for this chronic inflammatory skin disorder.

Bibliometric analysis and description of research trends in the treatment of psoriasis with biologic agents in the past two decades (2004-2023)

BACKGROUND

Biologics are essential in treating psoriasis. In recent years, the pathogenesis exploration and development of new target drugs have provided a more complete evidence-based foundation for the biological treatment of psoriasis. This study aims to use bibliometrics to analyze the research status and development trends of biologics in psoriasis.

METHODS

The bibliometric analysis of publications related to biologics in psoriasis from 2004 to 2023 was conducted using the Web of Science Core Collection (WoSCC) database as the search data source. To perform the bibliometric analysis and create visual knowledge graphs, CiteSpace, the Bibliometrix R package, and VOSviewers were utilized.

RESULTS

The study included a total of 3800 articles. The United States had the highest number of publications. The leading authors and institutions were Steven R. Feldman and the University of Manchester, respectively, in the global partnership. The cluster plot divided all keywords into 11 categories. Currently, Secukinumab and Guselkumab are representative biological agents being studied due to their considerable efficacy and long-term safety.

CONCLUSIONS

Targeted therapy has emerged as a significant trend in the current treatment of psoriasis. Early and active use of biologics can effectively control disease progression, prevent or delay the occurrence of comorbidities, and may even alter the natural course of psoriasis. However, further investigation is required to fully understand the specific mechanisms of psoriasis and the use of biological agents.

Lesional Psoriasis is Associated With Alterations in the Stratum Corneum Ceramide Profile and Concomitant Decreases in Barrier Function

Psoriasis is an inflammatory skin disease associated with an impaired skin barrier. The skin barrier function is dependent on the extracellular lipid matrix which surrounds the corneocytes in the stratum corneum. Ceramides comprise essential components of this matrix. Alterations in the stratum corneum ceramide profile have been directly linked to barrier dysfunction and might be an underlying factor of the barrier impairment in psoriasis. In this study, we investigated the ceramide profile and barrier function in psoriasis. Lesional and non-lesional skin of 26 patients and 10 healthy controls were analysed using in-depth ceramide lipidomics by liquid chromatography-mass spectrometry. Barrier function was assessed by measuring transepidermal water loss. Lesional skin showed a significant decrease in the abundance of total ceramides with significant alterations in the ceramide subclass composition compared to control and non-lesional skin. Additionally, the percentage of monounsaturated ceramides was significantly increased, and the average ceramide chain length significantly decreased in lesional skin. Altogether, this resulted in a markedly different profile compared to controls for lesional skin, but not for non-lesional skin. Importantly, the reduced barrier function in lesional psoriasis correlated to alterations in the ceramide profile, highlighting their interdependence. By assessing the parameters 2 weeks apart, we are able to highlight the reproducibility of these findings, which further affirms this connection. To conclude, we show that changes in the ceramide profile and barrier impairment are observed in, and limited to, lesional psoriatic skin. Their direct correlation provides a further mechanistic basis for the concomitantly observed impairment of barrier dysfunction.

Dynamic Boolean modeling of molecular and cellular interactions in psoriasis predicts drug target candidates

Psoriasis arises from complex interactions between keratinocytes and immune cells, leading to uncontrolled inflammation, immune hyperactivation, and a perturbed keratinocyte life cycle. Despite the availability of drugs for psoriasis management, the disease remains incurable. Treatment response variability calls for new tools and approaches to comprehend the mechanisms underlying disease development. We present a Boolean multiscale population model that captures the dynamics of cell-specific phenotypes in psoriasis, integrating discrete logical formalism and population dynamics simulations. Through simulations and network analysis, the model predictions suggest that targeting neutrophil activation in conjunction with inhibition of either prostaglandin E2 (PGE2) or STAT3 shows promise comparable to interleukin-17 (IL-17) inhibition, one of the most effective treatment options for moderate and severe cases. Our findings underscore the significance of considering complex intercellular interactions and intracellular signaling in psoriasis and highlight the importance of computational approaches in unraveling complex biological systems for drug target identification.

Genomic Profiling of the Overlap Phenotype between Psoriasis and Atopic Dermatitis

Clinical overlaps between psoriasis and atopic dermatitis (AD) are sometimes undiscernible, and there is no consensus on whether to treat the overlap phenotype as psoriasis or AD. We enrolled 41 patients diagnosed with either psoriasis or AD and clinically re-stratified them into classic psoriasis (n = 11), classic AD (n = 13), and the overlap phenotype between psoriasis and AD (n = 17). We compared the gene expression profiles of lesional and nonlesional skin biopsy tissues and the proteomic profiles of blood samples among the three comparison groups. Global mRNA expression and T-cell subset cytokine expression in the skin and protein biomarker elevation in the blood of the overlap phenotype were consistent with the profiles of psoriasis and different from the profiles of AD. Unsupervised k-means clustering indicated that the best number of distinct clusters for the total population of the three comparison groups was two, and the two clusters of psoriasis and AD were differentiated by gene expression. Our study suggests that the clinical overlap phenotype between psoriasis and AD has dominant molecular features of psoriasis, and genomic biomarkers can differentiate psoriasis and AD at molecular levels in patients with a spectrum of psoriasis and AD.

The elevation of plasma galectin-9 levels in patients with psoriasis and its associations with inflammatory and immune checkpoint molecules in skin tissues

Psoriasis is a chronic, immune-mediated disorder that mainly affects the skin, with an estimated global prevalence of 2-3%. Galectin-9 (Gal-9) is a β-galactoside-binding lectin capable of promoting or suppressing the progression of infectious and immune-mediated diseases. Here, we determined if the expression of Gal-9 is observed in psoriasis. Gal-9 levels were measured in plasma of psoriasis (n = 62) and healthy control (HC) (n = 31) using an enzyme-linked immunosorbent assay. In addition, skin samples from seven patients were screened for RNA transcriptomes and the expression of Gal-9 was compared with inflammatory, immune checkpoint molecules (ICMs) and Foxp3. The plasma Gal-9 levels in patients with psoriasis were significantly higher (841 pg/mL) than in HCs (617 pg/mL) (P < 0.0001) and were associated with white blood cell numbers, eosinophils (%) and alanine transaminase. The levels of inflammatory molecules IL-36B, IL-17RA, IL-6R, IL-10, IRF8, TGFb1, and IL-37, and those of ICMs of Tim-3, CTLA-4, CD86, CD80, PD-1LG2, CLEC4G, and Foxp3 were significantly correlated with Gal-9 (LGALS9) in skin. However, HMGB1, CD44, CEACAM1 and PDL1-known to be associated with a variety of Gal-9 biological functions were not correlated with LGALS9. Thus, it is likely that Gal-9 expression affects the disease state of PS.

The Expression of Activation Markers CD25 and CD69 Increases during Biologic Treatment of Psoriasis

CD (cluster of differentiation) 69 and CD25 are considered early and late markers of the activation of lymphocytes, respectively. CD25 is a part of the IL-2 receptor and is present on the surface of immune and non-immune cells, with high amounts on activated lymphocytes and regulatory T cells. CD69 is expressed on various types of white blood cells, including newly activated lymphocytes, lymphocytes infiltrating tissues isolated from subjects with chronic auto-inflammatory diseases, several subtypes of memory T cells and regulatory T cells. Primarily, CD69 was considered to be an early marker of the activation of lymphocytes, but, right now, data derived from in vitro and in vivo studies have revealed the immunomodulatory role of this surface antigen. In 84 patients with psoriasis, of whom 28 were treated with different biologic drugs, as well as in 29 healthy control subjects, the expression of CD25 and CD69 on different subtypes of peripheral blood mononuclear cells (PBMCs) was studied with the use of flow cytometry. Significantly higher levels of CD3/CD69-, CD8/CD69- and CD19/CD69-positive PBMCs as well as within CD3+ cells were present in subjects suffering from psoriasis when compared to healthy controls. In patients with psoriasis who were treated with biologic drugs, the levels of CD3/CD69-, CD4/CD69- and CD19/CD69-positive PBMCs, and CD3/CD69 within CD3+ cells, CD4/CD69 within CD4+ cells, CD4/CD25 within CD4+ cells and CD19/CD69 within CD19+ cells were significantly higher than before therapy. Our results support a role for activation markers, especially CD69, in psoriasis. Further research is warranted to fully clarify their significance in this common dermatosis, especially during biologic treatment.

Associations of A20, CYLD, Cezanne and JAK2 Genes and Immunophenotype with Psoriasis Susceptibility

Background and Objectives: Psoriasis is an immune-mediated chronic inflammatory skin disorder and commonly associated with highly noticeable erythematous, thickened and scaly plaques. Deubiquitinase genes, such as tumor necrosis factor-alpha protein 3 (TNFAIP3, A20), the cylindromatosis (CYLD) and Cezanne, function as negative regulators of inflammatory response through the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways. In this study, polymorphisms and expressions of A20, CYLD and Cezanne genes as well as immunophenotype in psoriatic patients were determined. Materials and Methods: In total, 82 patients with psoriasis and 147 healthy individuals with well-characterized clinical profiles were enrolled. Gene polymorphisms were determined by direct DNA sequencing, gene expression profile by quantitative real time-polymerase chain reaction (PCR), immunophenotype by flow cytometry, and the secretion of cytokines and cancer antigen (CA) 125 by enzyme-linked Immunosorbent assay (ELISA). Results: The inactivation of A20, CYLD and Cezanne and increased levels of TNF-α, IFN-γ and CA 125 was observed in psoriatic patients. Importantly, patients with low A20 expression had significant elevations of triglyceride and total cholesterol concentrations and higher numbers of CD13+CD117- and CD19+CD23+ (activated B) cells than those with high A20 expression. Genetic analysis indicated that all rs4495487 SNPs in the JAK2 gene, rs200878487 SNPs in the A20 gene and four SNPs (c.1584-375, c.1584-374, rs1230581026 and p.W433R) in the Cezanne gene were associated with significant risks, while the rs10974947 variant in the JAK2 gene was at reduced risk of psoriasis. Moreover, in the Cezanne gene, p.W433R was predicted to be probably damaging by the Polyphen-2 prediction tool and an AA/CC haplotype was associated with a high risk of psoriasis. In addition, patients with higher CA 125 levels than the clinical cutoff 35 U/mL showed increased levels of IFN-γ than those with normal CA 125 levels. Conclusions: A20 expression was associated with lipid metabolism and the recruitment of CD13+ CD117- and activated B cells into circulation in psoriatic patients. Besides this, the deleterious effect of the p.W433R variant in the Cezanne gene may contribute to the risk of psoriasis.

A quantitative systems pharmacology model for certolizumab pegol treatment in moderate-to-severe psoriasis

Background

Psoriasis is a chronic immune-mediated inflammatory systemic disease with skin manifestations characterized by erythematous, scaly, itchy and/or painful plaques resulting from hyperproliferation of keratinocytes. Certolizumab pegol [CZP], a PEGylated antigen binding fragment of a humanized monoclonal antibody against TNF-alpha, is approved for the treatment of moderate-to-severe plaque psoriasis. Patients with psoriasis present clinical and molecular variability, affecting response to treatment. Herein, we utilized an in silico approach to model the effects of CZP in a virtual population (vPop) with moderate-to-severe psoriasis. Our proof-of-concept study aims to assess the performance of our model in generating a vPop and defining CZP response variability based on patient profiles.

Methods

We built a quantitative systems pharmacology (QSP) model of a clinical trial-like vPop with moderate-to-severe psoriasis treated with two dosing schemes of CZP (200 mg and 400 mg, both every two weeks for 16 weeks, starting with a loading dose of CZP 400 mg at weeks 0, 2, and 4). We applied different modelling approaches: (i) an algorithm to generate vPop according to reference population values and comorbidity frequencies in real-world populations; (ii) physiologically based pharmacokinetic (PBPK) models of CZP dosing schemes in each virtual patient; and (iii) systems biology-based models of the mechanism of action (MoA) of the drug.

Results

The combination of our different modelling approaches yielded a vPop distribution and a PBPK model that aligned with existing literature. Our systems biology and QSP models reproduced known biological and clinical activity, presenting outcomes correlating with clinical efficacy measures. We identified distinct clusters of virtual patients based on their psoriasis-related protein predicted activity when treated with CZP, which could help unravel differences in drug efficacy in diverse subpopulations. Moreover, our models revealed clusters of MoA solutions irrespective of the dosing regimen employed.

Conclusion

Our study provided patient specific QSP models that reproduced clinical and molecular efficacy features, supporting the use of computational methods as modelling strategy to explore drug response variability. This might shed light on the differences in drug efficacy in diverse subpopulations, especially useful in complex diseases such as psoriasis, through the generation of mechanistically based hypotheses.

Human Mast Cells Upregulate Cathepsin B, a Novel Marker of Itch in Psoriasis

Mast cells (MCs) contribute to skin inflammation. In psoriasis, the activation of cutaneous neuroimmune networks commonly leads to itch. To dissect the unique contribution of MCs to the cutaneous neuroinflammatory response in psoriasis, we examined their density, distribution, relation to nerve fibres and disease severity, and molecular signature by comparing RNA-seq analysis of MCs isolated from the skin of psoriasis patients and healthy volunteers. In involved psoriasis skin, MCs and Calcitonin Gene-Related Peptide (CGRP)-positive nerve fibres were spatially associated, and the increase of both MC and nerve fibre density correlated with disease severity. Gene set enrichment analysis of differentially expressed genes in involved psoriasis skin showed significant representation of neuron-related pathways (i.e., regulation of neuron projection along with dendrite and dendritic spine morphogenesis), indicating MC engagement in neuronal development and supporting the evidence of close MC-nerve fibre interaction. Furthermore, the analysis of 208 identified itch-associated genes revealed that CTSB, TLR4, and TACR1 were upregulated in MCs in involved skin. In both whole-skin published datasets and isolated MCs, CTSB was found to be a reliable indicator of the psoriasis condition. Furthermore, cathepsin B+ cells were increased in psoriasis skin and cathepsin B+ MC density correlated with disease severity. Therefore, our study provides evidence that cathepsin B could serve as a common indicator of the MC-dependent itch signature in psoriasis.

Spatial transcriptomics stratifies psoriatic disease severity by emergent cellular ecosystems

Whereas the cellular and molecular features of human inflammatory skin diseases are well characterized, their tissue context and systemic impact remain poorly understood. We thus profiled human psoriasis (PsO) as a prototypic immune-mediated condition with a high predilection for extracutaneous involvement. Spatial transcriptomics (ST) analyses of 25 healthy, active lesion, and clinically uninvolved skin biopsies and integration with public single-cell transcriptomics data revealed marked differences in immune microniches between healthy and inflamed skin. Tissue-scale cartography further identified core disease features across all active lesions, including the emergence of an inflamed suprabasal epidermal state and the presence of B lymphocytes in lesional skin. Both lesional and distal nonlesional samples were stratified by skin disease severity and not by the presence of systemic disease. This segregation was driven by macrophage-, fibroblast-, and lymphatic-enriched spatial regions with gene signatures associated with metabolic dysfunction. Together, these findings suggest that mild and severe forms of PsO have distinct molecular features and that severe PsO may profoundly alter the cellular and metabolic composition of distal unaffected skin sites. In addition, our study provides a valuable resource for the research community to study spatial gene organization of healthy and inflamed human skin.

Transcriptome Analysis Identifies Biomarkers for the Diagnosis and Management of Psoriasis Complicated with Depression

Purpose

Psoriasis is a systemic inflammatory disease, and the mechanism that links psoriasis to depression is still elusive. Hence, this study aimed to elucidate the potential pathogenesis of psoriasis and depression comorbidity.

Methods

The gene expression profiles of psoriasis (GSE34248, GSE78097 and GSE161683) and depression (GSE39653) were downloaded from the Gene Expression Omnibus (GEO) DataSets. Functional annotation, protein-protein interaction (PPI) network and module construction, and hub gene identification and co-expression analysis were performed, following identification of the common differentially expressed genes (DEGs) of psoriasis and depression.

Results

A total of 115 common DEGs (55 up-regulated and 60 down-regulated) were identified between psoriasis and depression. Functional analysis indicated that T cell activation and differentiation were predominantly implicated in the potential pathogenesis of these two diseases. In addition, Th17 cell differentiation and cytokines is closely related to both. Finally, 17 hub genes were screened, including CTLA4, LCK, ITK, IL7R, CD3D, SOCS1, IL4R, PRKCQ, SOCS3, IL23A, PDGFB, PAG1, TGFA, FGFR1, RELN, ITGB5 and TNXB, which re-emphasized the importance of the immune system in psoriasis and depression.

Conclusion

Our study reveals the common pathogenesis of psoriasis and depression. These common pathways and hub genes may apply to a molecular screening tool for depression in psoriasis patients, which could help dermatologists optimize patient management in routine care.

The Long Noncoding RNA LINC00958 Is Induced in Psoriasis Epidermis and Modulates Epidermal Proliferation

Psoriasis is a common, immune-mediated skin disease characterized by epidermal hyperproliferation and chronic skin inflammation. Long noncoding RNAs are >200 nucleotide-long transcripts that possess important regulatory functions. To date, little is known about the contribution of long noncoding RNAs to psoriasis. In this study, we identify LINC00958 as a long noncoding RNA overexpressed in keratinocytes (KCs) from psoriasis skin lesions, in a transcriptomic screen performed on KCs sorted from psoriasis and healthy skin. Increased levels of LINC00958 in psoriasis KCs were confirmed by RT-qPCR and single-molecule in situ hybridization. Confocal microscopy and analysis of subcellular fractions showed that LINC00958 is mainly localized in the cytoplasm of KCs. IL-17A, a key psoriasis cytokine, induced LINC00958 in KCs through C/EBP-β and the p38 pathway. The inhibition of LINC00958 led to decreased proliferation as measured by Ki-67 expression, IncuCyte imaging, and 5-ethynyl-2-deoxyuridine assays. Transcriptomic analysis of LINC00958-depleted KCs revealed enrichment of proliferation- and cell cycle‒related genes among differentially expressed transcripts. Moreover, LINC00958 depletion led to decreased basal and IL-17A‒induced phosphorylation of p38. Furthermore, IL-17A‒induced KC proliferation was counteracted by the inhibition of LINC00958. In summary, our data support a role for the IL-17A‒induced long noncoding RNA, LINC00958, in the pathological circuits of psoriasis by reinforcing IL-17A‒induced epidermal hyperproliferation.

A prediction model identifying glycolysis signature as therapeutic target for psoriasis

Background

The hyperproliferation featured with upregulated glycolysis is a hallmark of psoriasis. However, molecular difference of keratinocyte glycolysis amongst varied pathologic states in psoriasis remain elusive.

Objectives

To characterize glycolysis status of psoriatic skin and assess the potential of glycolysis score for therapeutic decision.

Methods

We analyzed 345414 cells collected from different cohorts of single-cell RNA seq database. A new method, Scissor, was used to integrate the phenotypes in GSE11903 to guide single-cell data analysis, allowing identification of responder subpopulations. AUCell algorithm was performed to evaluate the glycolysis status of single cell. Glycolysis signature was used for further ordering in trajectory analysis. The signature model was built with logistic regression analysis and validated using external datasets.

Results

Keratinocytes (KCs) expressing SLC2A1 and LDH1 were identified as a novel glycolysis-related subpopulation. Scissor⁺ cells and Scissor^- cells were defined as response and non-response phenotypes. In Scissor⁺ SLC2A1⁺ LDH1⁺ KCs, ATP synthesis pathway was activated, especially, the glycolysis pathway being intriguing. Based on the glycolysis signature, keratinocyte differentiation was decomposed into a three-phase trajectory of normal, non-lesional, and lesional psoriatic cells. The area under the curve (AUC) and Brier score (BS) were used to estimate the performance of the glycolysis signature in distinguishing response and non-response samples in GSE69967 (AUC =0.786, BS =17.7) and GSE85034 (AUC=0.849, BS=11.1). Furthermore, Decision Curve Analysis suggested that the glycolysis score was clinically practicable.

Conclusion

We demonstrated a novel glycolysis-related subpopulation of KCs, identified 12-glycolysis signature, and validated its promising predictive efficacy of treatment effectiveness.

Cathelicidin Antimicrobial Peptide LL37 Induces Toll-Like Receptor 8 and Amplifies IL-36γ and IL-17C in Human Keratinocytes

LL37 is produced by skin injury and bacterial infection and plays an important role in the early stages of psoriasis. In particular, the intracellular receptors toll-like receptors (TLR)3, TLR7, TLR8, and TLR9 are thought to be involved in the pathogenesis of psoriasis in conjunction with LL37, but the interaction between TLR7/8 and LL37 in keratinocytes (KCs) remains unclear. This study aimed to clarify the relationship between LL37 and TLR7/8 in KCs and their involvement in the pathogenetic pathways seen in psoriasis using cultured KCs and skin samples of patients with psoriasis. TLR7/8 was induced by LL37 in KCs. TLR8 but not TLR7 functionally induced many psoriasis-related molecules, whereas IL-17C was not altered by the blockade of TLR7/8. Although costimulation of LL37 with self-RNA/DNA did not show any interaction, LL37 itself would promote psoriasis-related genes. IL-36 receptor antagonistic antibody suppressed IL-17C induced by LL37. In psoriatic epidermis, LL37, TLRs, IL-17C, and IL-36γ expressions were increased and coexpressed with each other. Thus, we concluded that LL37 activates TLR8 in KCs and induces IL-17C through the induction of IL-36γ. Regulation of TLR8 or LL37 in KCs could be a potential therapeutic strategy for psoriatic inflammation.

The imbalance between Type 17 T-cells and regulatory immune cell subsets in psoriasis vulgaris

Psoriasis vulgaris is a common inflammatory disease affecting 7.5 million adults just in the US. Previously, psoriasis immunopathogenesis has been viewed as the imbalance between CD4⁺ T-helper 17 (Th17) cells and regulatory T-cells (Tregs). However, current paradigms are rapidly evolving as new technologies to study immune cell subsets in the skin have been advanced. For example, recently minted single-cell RNA sequencing technology has provided the opportunity to compare highly differing transcriptomes of Type 17 T-cell (T17 cell) subsets depending on IL-17A vs. IL-17F expression. The expression of regulatory cytokines in T17 cell subsets provided evidence of T-cell plasticity between T17 cells and regulatory T-cells (Tregs) in humans. In addition to Tregs, other types of regulatory cells in the skin have been elucidated, including type 1 regulatory T-cells (Tr1 cells) and regulatory dendritic cells. More recently, investigators are attempting to apply single-cell technologies to clinical trials of biologics to test if monoclonal blockade of pathogenic T-cells will induce expansion of regulatory immune cell subsets involved in skin homeostasis.

Large-scale serum analysis identifies unique systemic biomarkers in psoriasis and hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is now recognized as a systemic inflammatory disease, sharing molecular similarities with psoriasis. Direct comparison of the systemic inflammation in HS with psoriasis is lacking.

OBJECTIVES

To evaluate the serum proteome of HS and psoriasis, and to identify biomarkers associated with disease severity.

METHODS

In this cross-sectional study, 1536 serum proteins were assessed using the Olink Explore (Proximity Extension Assay) high-throughput panel in patients with moderate-to-severe HS (n = 11), patients with psoriasis (n = 10) and age- and body mass index-matched healthy controls (n = 10).

RESULTS

HS displayed an overall greater dysregulation of circulating proteins, with 434 differentially expressed proteins (absolute fold change ≥ 1·2; P ≤ 0·05) in patients with HS vs. controls, 138 in patients with psoriasis vs. controls and 503 between patients with HS and patients with psoriasis. Interleukin (IL)-17A levels and T helper (Th)1/Th17 pathway enrichment were comparable between diseases, while HS presented greater tumour necrosis factor- and IL-1β-related signalling. The Th17-associated markers peptidase inhibitor 3 (PI3) and lipocalin 2 (LCN2) were able to differentiate psoriasis from HS accurately. Both diseases presented increases of atherosclerosis-related proteins. Robust correlations between clinical severity scores and immune and atherosclerosis-related proteins were observed across both diseases.

CONCLUSIONS

HS and psoriasis share significant Th1/Th17 enrichment and upregulation of atherosclerosis-related proteins. Despite the greater body surface area involved in psoriasis, HS presents a greater serum inflammatory burden.

Quantification of Immunohistochemically Stained Cells in Skin Biopsies

Immunohistochemical quantification of inflammatory cells in skin biopsies is a valuable tool for diagnosing skin diseases and assessing treatment response. The quantification of individual cells in biopsies is time-consuming, tedious, and difficult. In this study, we presented and compared two methods for the quantification of CD8⁺ T cells in skin biopsies from patients with psoriasis using both commercial software (Adobe Photoshop) and open-source software (Qupath). In addition, we provided a detailed, step-by-step description of both methods. The methods are scalable by replacing the CD8 antibody with other antibodies to target different cells. Moreover, we investigated the correlation between quantifying CD8⁺ cells normalized to area or epidermal length and cell classifications, compared cell classifications in QuPath with threshold classifications in Photoshop, and analyzed the impact of data normalization to epidermal length or area on inflammatory cell densities in skin biopsies from patients with psoriasis. We found a satisfactory correlation between normalizing data to epidermal length and area for psoriasis skin. However, when non-lesional and lesional skin samples were compared, a significant underestimation of inflammatory cell density was found when data were normalized to area instead of epidermal length. Finally, Bland–Altman plots comparing Qupath and Photoshop to quantify inflammatory cell density demonstrated a good agreement between the two methods.

Functional study of TNF-α promoter polymorphisms in psoriasis

BACKGROUND

TNF-α is an important mediator in the pathogenesis of psoriasis and polymorphisms influence its transcription and could be implicated in psoriasis risk and modify certain aspects of disease, such as age at onset of psoriasis vulgaris and disease severity. Six TNF-α single nucleotide polymorphisms (SNPs) in promoter region has been identified and studied but with discordant results. The aim of this study was to evaluate whether the polymorphisms in TNF-α (-238 (rs361525), -308 (rs1800629), -857 (rs1799724), -1031 (rs1799964)) are associated with gravity, prurity, early onset or response to drug therapy in psoriasis in Caucasian Italian patients.

METHODS

58 psoriasis patients from Turin PSOCARE, 23 with psoriasis vulgaris and 35 with psoriatic arthritis were studied. Ready to used master mix for allelic discrimination of rs1800629, rs361525 and rs1799964 respectively.

RESULTS

Our data showed a significant association between the -857(G) variant and both VAS-itch (p=0,03) and VAS-pain index (p=0,006), OR=0,2 (0,04-0,98) and OR=0,12 (0,02-0,59). No significant association between the genotypes or alleles of TNF-α SNPs as been observed with other clinic-pathologic parameters or etanercept response.

CONCLUSIONS

Our data suggest that -857 CC genotype could be involved in pain and itch severity in psoriasis patients.

Profiles of Innate Immune Cell Infiltration and Related Core Genes in Psoriasis

Psoriasis is an inflammatory skin disease with substantial morbidity. Numerous patients with psoriasis experience recurrence after therapy. The underlying mechanism about psoriasis is still not fully understood. Some evidences suggest that innate immunity may play an unexpected and important role in active severe psoriasis. In this work, the deconvolution algorithm CIBERSORT was conducted to identify the infiltration of innate immune cells and related core genes in psoriatic plaque. Datasets from the Gene Expression Omnibus, including skin samples from 405 psoriasis patients and 91 healthy donors, were downloaded for analysis. Considerable differences of the innate immune cell composition were uncovered between psoriatic plaque and control skin. Results revealed that γδ T cells, resting NK cells, M0 macrophages, M1 macrophages, activated dendritic cells, and neutrophils were significantly increased in psoriatic skin, while resting mast cells and active NK cells were significantly decreased. Moreover, the proportion of M0 macrophages or resting mast cells was found to be associated with disease severity. Spearman correlation analysis suggests that RORC and S100A12 genes were related to disease severity, while genes including S100A12, CLEC4C, IL-19, AIM2, IL-17F, and PPARGC1A were correlated with biologic treatment response. In conclusion, this work displays innate immune status in psoriatic skin and provides novel clues for clinical decisions and mechanism study.

Insights into interplay of immunopathophysiological events and molecular mechanistic cascades in psoriasis and its associated comorbidities

Psoriasis is an inflammatory skin disease with complex pathogenesis and multiple etiological factors. Besides the essential role of autoreactive T cells and constellation of cytokines, the discovery of IL-23/Th17 axis as a central signaling pathway has unraveled the mechanism of accelerated inflammation in psoriasis. This has provided insights into psoriasis pathogenesis and revolutionized the development of effective biological therapies. Moreover, genome-wide association studies have identified several candidate genes and susceptibility loci associated with this disease. Although involvement of cellular innate and adaptive immune responses and dysregulation of immune cells have been implicated in psoriasis initiation and maintenance, there is still a lack of unifying mechanism for understanding the pathogenesis of this disease. Emerging evidence suggests that psoriasis is a high-mortality disease with additional burden of comorbidities, which adversely affects the treatment response and overall quality of life of patients. Furthermore, changing trends of psoriasis-associated comorbidities and shared patterns of genetic susceptibility, risk factors and pathophysiological mechanisms manifest psoriasis as a multifactorial systemic disease. This review highlights the recent progress in understanding the crucial role of different immune cells, proinflammatory cytokines and microRNAs in psoriasis pathogenesis. In addition, we comprehensively discuss the involvement of various complex signaling pathways and their interplay with immune cell markers to comprehend the underlying pathophysiological mechanism, which may lead to exploration of new therapeutic targets and development of novel treatment strategies to reduce the disastrous nature of psoriasis and associated comorbidities.

Transcriptomic landscaping of core genes and pathways of mild and severe psoriasis vulgaris

Psoriasis is a common chronic inflammatory skin disease affecting >125 million individuals worldwide. The therapeutic course for the disease is generally designed upon the severity of the disease. In the present study, the gene expression profile GSE78097, was retrieved from the National Centre of Biotechnology (NCBI)‑Gene Expression Omnibus (GEO) database to explore the differentially expressed genes (DEGs) in mild and severe psoriasis using the Affy package in R software. The Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways of the DEGs were analysed using clusterProfiler, Bioconductor, version 3.8. In addition, the STRING database was used to develop DEG‑encoded proteins and a protein‑protein interaction network (PPI). Cytoscape software, version 3.7.1 was utilized to construct a protein interaction association network and analyse the interaction of the candidate DEGs encoding proteins in psoriasis. The top 2 hub genes in Cytohubba plugin parameters were validated using immunohistochemical analysis in psoriasis tissues. A total of 382 and 3,001 dysregulated mild and severe psoriasis DEGs were reported, respectively. The dysregulated mild psoriasis genes were enriched in pathways involving cytokine‑cytokine receptor interaction and rheumatoid arthritis, whereas cytokine‑cytokine receptor interaction, cell cycle and cell adhesion molecules were the most enriched pathways in severe psoriasis group. PL1N1, TLR4, ADIPOQ, CXCL8, PDK4, CXCL1, CXCL5, LPL, AGT, LEP were hub genes in mild psoriasis, whereas BUB1, CCNB1, CCNA2, CDK1, CDH1, VEGFA, PLK1, CDC42, CCND1 and CXCL8 were reported hub genes in severe psoriasis. Among these, CDC42, for the first time (to the best of our knowledge), has been reported in the psoriasis transcriptome, with its involvement in the adaptive immune pathway. Furthermore, the immunoexpression of CDK1 and CDH1 proteins in psoriasis skin lesions were demonstrated using immunohistochemical analysis. On the whole, the findings of the present integrated bioinformatics and immunohistochemical study, may enhance our understanding of the molecular events occurring in psoriasis, and these candidate genes and pathways together may prove to be therapeutic targets for psoriasis vulgaris.

Pathogenesis of psoriasis in the "omic" era. Part I. Epidemiology, clinical manifestation, immunological and neuroendocrine disturbances

Psoriasis is a common, chronic, inflammatory, immune-mediated skin disease affecting about 2% of the world's population. According to current knowledge, psoriasis is a complex disease that involves various genes and environmental factors, such as stress, injuries, infections and certain medications. The chronic inflammation of psoriasis lesions develops upon epidermal infiltration, activation, and expansion of type 1 and type 17 Th cells. Despite the enormous progress in understanding the mechanisms that cause psoriasis, the target cells and antigens that drive pathogenic T cell responses in psoriatic lesions are still unproven and the autoimmune basis of psoriasis still remains hypothetical. However, since the identification of the Th17 cell subset, the IL-23/Th17 immune axis has been considered a key driver of psoriatic inflammation, which has led to the development of biologic agents that target crucial elements of this pathway. Here we present the current understanding of various aspects in psoriasis pathogenesis.

Review-Current Concepts in Inflammatory Skin Diseases Evolved by Transcriptome Analysis: In-Depth Analysis of Atopic Dermatitis and Psoriasis

During the last decades, high-throughput assessment of gene expression in patient tissues using microarray technology or RNA-Seq took center stage in clinical research. Insights into the diversity and frequency of transcripts in healthy and diseased conditions provide valuable information on the cellular status in the respective tissues. Growing with the technique, the bioinformatic analysis toolkit reveals biologically relevant pathways which assist in understanding basic pathophysiological mechanisms. Conventional classification systems of inflammatory skin diseases rely on descriptive assessments by pathologists. In contrast to this, molecular profiling may uncover previously unknown disease classifying features. Thereby, treatments and prognostics of patients may be improved. Furthermore, disease models in basic research in comparison to the human disease can be directly validated. The aim of this article is not only to provide the reader with information on the opportunities of these techniques, but to outline potential pitfalls and technical limitations as well. Major published findings are briefly discussed to provide a broad overview on the current findings in transcriptomics in inflammatory skin diseases.

Characterization of disease-specific cellular abundance profiles of chronic inflammatory skin conditions from deconvolution of biopsy samples

BACKGROUND

Psoriasis and atopic dermatitis are two inflammatory skin diseases with a high prevalence and a significant burden on the patients. Underlying molecular mechanisms include chronic inflammation and abnormal proliferation. However, the cell types contributing to these molecular mechanisms are much less understood. Recently, deconvolution methodologies have allowed the digital quantification of cell types in bulk tissue based on mRNA expression data from biopsies. Using these methods to study the cellular composition of the skin enables the rapid enumeration of multiple cell types, providing insight into the numerical changes of cell types associated with chronic inflammatory skin conditions. Here, we use deconvolution to enumerate the cellular composition of the skin and estimate changes related to onset, progress, and treatment of these skin diseases.

METHODS

A novel signature matrix, i.e. DerM22, containing expression data from 22 reference cell types, is used, in combination with the CIBERSORT algorithm, to identify and quantify the cellular subsets within whole skin biopsy samples. We apply the approach to public microarray mRNA expression data from the skin layers and 648 samples from healthy subjects and patients with psoriasis or atopic dermatitis. The methodology is validated by comparison to experimental results from flow cytometry and immunohistochemistry studies, and the deconvolution of independent data from isolated cell types.

RESULTS

We derived the relative abundance of cell types from healthy, lesional, and non-lesional skin and observed a marked increase in the abundance of keratinocytes and leukocytes in the lesions of both inflammatory dermatological conditions. The relative fraction of these cells varied from healthy to diseased skin and from non-lesional to lesional skin. We show that changes in the relative abundance of skin-related cell types can be used to distinguish between mild and severe cases of psoriasis and atopic dermatitis, and trace the effect of treatment.

CONCLUSIONS

Our analysis demonstrates the value of this new resource in interpreting skin-derived transcriptomics data by enabling the direct quantification of cell types in a skin sample and the characterization of pathological changes in tissue composition.

Assessment and Clinical Relevance of Serum IL-19 Levels in Psoriasis and Atopic Dermatitis Using a Sensitive and Specific Novel Immunoassay

Because development of reliable biomarkers in psoriasis and atopic dermatitis has lagged behind therapeutic progress, we created a blood-based test to fill the void in objective methods available for dermatological assessments. Our novel interleukin-19 (IL-19) immunoassay was initially tested to determine concentrations of IL-19 serum levels, then correlated with the psoriasis activity and severity index (PASI) in psoriasis, and the eczema area and severity index (EASI) in atopic dermatitis. Not only was IL-19 increased in psoriasis and correlated to PASI, but ixekizumab administration led to rapid, sustained IL-19 decreases to normal levels, with decreases at 2-weeks correlating with PASI improvement at 16-weeks. IL-19 increased upon ixekizumab withdraw, prior to relapse, and decreased following re-treatment. In baricitinib- and etanercept-treated psoriasis patients, IL-19 decreases also correlated with improvement. Many patients with limited skin disease, including genital psoriasis and psoriatic arthritis patients, also had increased IL-19, which was reduced to normal levels upon ixekizumab treatment, correlating with PASI improvement. We also measured IL-19 in baricitinib-treated atopic dermatitis patients. In atopic dermatitis, IL-19 was significantly elevated, correlated with EASI scores, and decreased with skin improvement. Therefore, measurement of serum IL-19 provides clinicians with an objective disease-activity assessment tool for psoriasis and atopic dermatitis patients.

Immune regulation mechanism of vitamin D level and IL-17/IL-17R pathway in Crohn's disease

Immune regulation mechanism of vitamin D level and interleukin (IL)-17/IL-17 receptor (IL-17R) pathway in Crohn's disease was studied. Of 40 clean mature healthy rats, 10 rats were used as control group based on random number table, the remaining 30 rats to establish Crohn's disease rat models. After successful modeling, 30 rats were divided into model group, low-dose group and high-dose group with random number table. On the 1st day after modeling, rats in low-dose group were given a single dose of 1,750 IU of vitamin D, and rats in high-dose group a single dose of 7,500 IU of vitamin D. Changes in the condition of rats after modeling were observed and scored. Enzyme-linked immunosorbent assay was used for detecting IL-12, IL-17 and CXCL11 levels, western blotting for detecting IL-17R level, and flow cytometry for detecting Th1 cell and Th17 cell levels in the lamina propria of colon mucosa. Disease activity index scores were significantly lower in low-dose group and high-dose group of rats than those in model group (P<0.05). Those were significantly lower in high-dose group of rats than those in low-dose group (P<0.05). IL-17 and IL-17R levels were significantly lower in high-dose group of rats than those in low-dose group (P<0.05). Th1 cell level was significantly higher in high-dose group of rats than that in low-dose group (P<0.05), but Th17 cell level was lower than that in low-dose group (P<0.05). IL-12 levels were significantly higher in model group, low-dose group and highdose group of rats than those in control group (P<0.05). CXCL11 levels were significantly lower in model group, low-dose group and high-dose group of rats than those in control group (P<0.05). Vitamin D can effectively treat Crohn's disease, which may improve the chemotaxis and differentiation of Th1 cells by inhibiting IL-17/IL-17R pathway, thereby improving immune function and reducing the severity of disease.

Emerging role of immune cell network in autoimmune skin disorders: An update on pemphigus, vitiligo and psoriasis

Autoimmune skin diseases are a group of disorders that arise due to a deregulated immune system resulting in skin tissue destruction. In the majority of these conditions, either autoreactive immune cells or the autoantibodies are generated against self-antigens of the skin. Although the etiology of these diseases remains elusive, biochemical, genetic, and environmental factors such as infectious agents, toxins damage the skin tissue leading to self-antigen generation, autoantibody attack and finally results in autoimmunity of skin. Immune dysregulation, which involves predominantly T helper 1/17 (Th1/Th17) polarization and the inability of regulatory T cells to regress immune response, is implicated in autoimmune skin diseases. The emerging roles of immune cells, cytokines, and chemokines in the pathogenesis of common autoimmune skin diseases like pemphigus, vitiligo, and psoriasis are discussed in this review. The main focus is on the interplay between immune cell network including the innate and adaptive immune system, regulatory cells, immune checkpoints and recently identified tissue-resident memory cells (TRMs) in disease pathogenesis and relapse. We also attempt to highlight on the immune mechanisms common to these diseases which can be targeted for designing novel therapeutics.

Distinct transcriptomic profiles of early-onset atopic dermatitis in blood and skin of pediatric patients

BACKGROUND

Atopic dermatitis (AD) predominantly affects young children, but our understanding of AD pathogenesis is based on skin and blood samples from long-standing adult AD. Genomic biopsy profiling from early pediatric AD showed significant Th2 and Th17/Th22-skewing, without the characteristic adult Th1 up-regulation. Because obtaining pediatric biopsies is difficult, blood gene expression profiling may provide a surrogate for the pediatric skin signature.

OBJECTIVE

To define the blood profile and associated biomarkers of early moderate-to-severe pediatric AD.

METHODS

We compared microarrays and reverse transcription polymerase chain reaction (RT-PCR) of blood cells from 28 AD children (<5 years and within 6 months of disease onset) to healthy control blood cells. Differentially expressed genes (DEGs) in blood (fold change [FCH] > 1.2 and false discovery rate [FDR] < 0.05) were then compared with skin DEGs.

RESULTS

Eosinophil and Th2 markers (IL5RA, IL1RL1/ST2, HRH4, CCR3, SIGLEC8, PRSS33, CLC from gene arrays; IL13/IL4/CCL22 from RT-PCR) were up-regulated in early pediatric AD blood, whereas IFNG/Th1 was decreased. Th1 markers were negatively correlated with clinical severity (EASI, pruritus, transepidermal water loss [TEWL]), whereas Th2/Th17-induced interleukin (IL)-19 was positively correlated with SCORAD. Although a few RT-PCR-defined immune markers (IL-13/CCL22) were increased in blood, as previously also reported for skin, minimal overlap based on gene array DEGs was seen.

CONCLUSION

The whole blood signature of early moderate-to-severe pediatric AD blood cells show predominantly a Th2/eosinophil profile; however, markers largely differ from the skin profile. Given their complementarity, pooling of biomarkers from blood and skin may improve profiling and predictions, providing insight regarding disease course, allergic comorbidity development, and response to systemic medications.

Ichthyosis molecular fingerprinting shows profound TH17 skewing and a unique barrier genomic signature

BACKGROUND

Ichthyoses are a group of rare skin disorders lacking effective treatments. Although genetic mutations are progressively delineated, comprehensive molecular phenotyping of ichthyotic skin could suggest much-needed pathogenesis-based therapy.

OBJECTIVE

We sought to profile the molecular fingerprint of the most common orphan ichthyoses.

METHODS

Gene, protein, and serum studies were performed on skin and blood samples from 29 patients (congenital ichthyosiform erythroderma, n = 9; lamellar ichthyosis, n = 8; epidermolytic ichthyosis, n = 8; and Netherton syndrome, n = 4), as well as age-matched healthy control subjects (n = 14), patients with psoriasis (n = 30), and patients with atopic dermatitis (AD; n = 16).

RESULTS

Using criteria of a fold change of greater than 2 and a false discovery rate of less than 0.05, 132 differentially expressed genes were shared commonly among all ichthyoses, including many IL-17 and TNF-α-coregulated genes, which are considered hallmarks of psoriasis (defensin beta 4A, kynureninase, and vanin 3). Although striking upregulation of TH17 pathway genes (IL17F and IL36B/G) resembling that seen in patients with psoriasis was common to all patients with ichthyoses in a severity-related manner, patients with Netherton syndrome showed the greatest T-cell activation (inducible costimulator [ICOS]) and a broader immune phenotype with T_H1/IFN-γ, OASL, and T_H2/IL-4 receptor/IL-5 skewing, although less than seen in patients with AD (all P < .05). Ichthyoses lacked the epidermal differentiation and tight junction alterations of patients with AD (loricrin, filaggrin, and claudin 1) but showed characteristic alterations in lipid metabolism genes (ELOVL fatty acid elongase 3 and galanin), with parallel reductions in extracellular lipids and corneocyte compaction in all ichthyoses except epidermolytic ichthyosis, suggesting phenotypic variations. Transepidermal water loss, a functional barrier measure, significantly correlated with IL-17-regulated gene expression (IL17F and IL36A/IL36B/IL36G).

CONCLUSION

Similar to patients with AD and psoriasis, in whom cytokine dysregulation and barrier impairment orchestrate disease phenotypes, psoriasis-like immune dysregulation and lipid alterations characterize the ichthyoses. These data support the testing of IL-17/IL-36-targeted therapeutics for patients with ichthyosis similar to those used in patients with psoriasis.

Molecular action of isoflavone genistein in the human epithelial cell line HaCaT

Due to its strong proliferation-reducing effects on keratinocytes, and also anti-inflammatory properties, the isoflavone genistein has already been proposed as a possible antipsoriatic compound. As there is still no detailed information on this topic, we examined the effects of genistein by using an in vitro model of both, normal and "psoriasis-like" keratinocytes at this stage of our work exhaustively testing the selected flavonoid in a mono-treated experimental design. Gene expression studies revealed transcriptional changes that confirms known disease-associated pathways and highlights many psoriasis-related genes. Our results suggested that aberrant expression of genes contributing to the progress of psoriasis could be improved by the action of genistein. Genistein prevented "cytokine mix" as well as TNF-α-induced NF-κB nuclear translocation, with no effect on the PI3K signaling cascade, indicating the luck of turning this pathway into NF-κB activation. It could have attenuated TNF-α and LPS-induced inflammatory responses by suppressing ROS activation. Regardless of the type of keratinocyte stimulation used, reduction of cytokine IL-8, IL-20 and CCL2 production (both at RNA and protein level) following genistein treatment was visible. Because investigations of other groups supported our commentary on potential administration of genistein as a potential weapon in the armamentarium against psoriasis, it is believed that this paper should serve to encourage researchers to conduct further studies on this subject.

The expression of mCTLA-4 in skin lesion inversely correlates with the severity of psoriasis

BACKGROUND

Psoriasis is a chronic inflammatory disease characterized by epidermal hyperplasia and increased T cell infiltration. Cytotoxic T lymphocyte antigen-4 (CTLA-4) is a key factor that affects T cell function and immune response. However, whether the expression of CTLA-4 affects the severity of psoriasis is still unknown.

OBJECTIVE

The aim of the project was to investigate the correlation between the expression of CTLA-4 and the severity of psoriasis.

METHODS

The plasma soluble CTLA-4 levels and membrane CTLA-4 expression were measured by enzyme-linked immunosorbent assay and immunohistochemistry analysis in mild, moderate and severe psoriasis patients, respectively. Imiquimod-induced mouse model of psoriasis was treated with CTLA-4 immunoglobulin fusion protein (CTLA-4 Ig) or anti-CTLA-4 antibody. Epidermal thickness and infiltrating CD3+ T cell counts were evaluated.

RESULTS

The plasma soluble CTLA-4 levels had no significant difference among mild, moderate, and severe patients (p > 0.05). However, the membrane CTLA-4 expression in skin was significantly higher in mild psoriasis patients compared to moderate and severe psoriasis patients (17652.86 ± 18095.66 vs 6901.36 ± 4400.77 vs 3970.24 ± 5509.15, p < 0.001). Furthermore, in imiquimod-induced mouse model of psoriasis, the results showed that mimicking CTLA-4 function improved the skin phenotype and reduced epidermal thickness (172.87 ± 28.25 vs 245.87 ± 36.61 μm, n = 6, p < 0.01) as well as infiltrating CD3+ T cell counts (5.09 ± 3.45 vs 13.45 ± 4.70, p < 0.01) compared to control group. However, blocking CTLA-4 function aggregated the skin phenotype including enhanced epidermal thickness and infiltrating CD3+ T cell counts compared to control group.

CONCLUSION

These results indicated that the expression of mCTLA-4 in skin lesion inversely correlated with the severity of psoriasis and CTLA-4 might play a critical role in the disease severity of psoriasis.

The role of regulatory T cells and genes involved in their differentiation in pathogenesis of selected inflammatory and neoplastic skin diseases. Part II: The Treg role in skin diseases pathogenesis

Regulatory FOXP3+ T cells (Tregs) constitute 5% to 10% of T cells in the normal human skin. They play an important role in the induction and maintenance of immunological tolerance. The suppressive effects of these cells are exerted by various mechanisms including the direct cytotoxic effect, anti-inflammatory cytokines, metabolic disruption, and modulation of the dendritic cells function. The deficiency of Treg cells number or function are one of the basic elements of the pathogenesis of many skin diseases, such as psoriasis, atopic dermatitis, bacterial and viral infections. They also play a role in the pathogenesis of T cell lymphomas of the skin (cutaneous T cell lymphomas - CTCL), skin tumors and mastocytosis. Here, in the second part of the cycle, we describe dysfunctions of Tregs in selected skin diseases.

Signs of innate immune activation and premature immunosenescence in psoriasis patients

Psoriasis is a chronic inflammatory disease that affects skin and is associated with systemic inflammation and many serious comorbidities ranging from metabolic syndrome to cancer. Important discoveries about psoriasis pathogenesis have enabled the development of effective biological treatments blocking the T helper 17 pathway. However, it has not been settled whether psoriasis is a T cell-mediated autoimmune disease or an autoinflammatory disorder that is driven by exaggerated innate immune signalling. Our comparative gene expression and hierarchical cluster analysis reveal important gene circuits involving innate receptors. Innate immune activation is indicated by increased absent in melanoma 2 (AIM2) inflammasome gene expression and active caspase 1 staining in psoriatic lesional skin. Increased eomesodermin (EOMES) expression in lesional and non-lesional skin is suggestive of innate-like virtual memory CD8+ T cell infiltration. We found that signs of systemic inflammation were present in most of the patients, correlated with the severity of the disease, and pointed to IL-6 involvement in the pathogenesis of psoriatic arthritis. Among the circulating T cell subpopulations, we identified a higher proportion of terminally differentiated or senescent CD8+ T cells, especially in patients with long disease duration, suggesting premature immunosenescence and its possible implications for psoriasis co-morbidities.

Basic and Translational Science: A Report from the GRAPPA 2016 Annual Meeting

Rapid advances in effective treatments for psoriasis and psoriatic arthritis (PsA) have emerged from improved understanding of cell subsets and critical mediators that promote tissue inflammation and destruction. More specifically, increased knowledge of innate immunity and the important involvement of cytokines in the interleukin (IL)-23-IL-17 axis as key mediators of psoriatic plaque and joint inflammation in both psoriasis and PsA have led to new theories of immunopathogenesis. Herein we summarize recent discussions on IL-17-related pathways and their relationship to psoriasis and PsA.

A randomized clinical trial in vitamin D-deficient adults comparing replenishment with oral vitamin D3 with narrow-band UV type B light: effects on cholesterol and the transcriptional profiles of skin and blood

Background: Vitamin D deficiency, defined as a serum 25-hydroxyvitamin D [25(OH)D] concentration <20 ng/mL, is correlated with a more atherogenic lipid profile. However, oral vitamin D supplementation does not lower LDL-cholesterol concentrations or raise HDL-cholesterol concentrations. This uncoupling between association and causation may result from a failure of oral vitamin D to mimic the effect of dermally synthesized vitamin D in response to ultraviolet type B (UVB) light.Objective: We tested the hypothesis that, in vitamin D-deficient adults, the replenishment of vitamin D with UVB exposure would lower LDL-cholesterol concentrations compared with the effect of oral vitamin D₃ supplementation.Design: We performed a randomized clinical trial in vitamin D-deficient adults and compared vitamin D replenishment between subjects who received oral vitamin D₃ (n = 60) and those who received narrow-band UVB exposure (n = 58) ≤6 mo.Results: There was no difference in the change from baseline LDL-cholesterol concentrations between oral vitamin D₃ and UVB groups (difference in median of oral vitamin D₃ minus that of UVB: 1.5 mg/dL; 95% CI: -5.0, 7.0 mg/dL). There were also no differences within groups or between groups for changes in total or HDL cholesterol or triglycerides. Transcriptional profiling of skin and blood, however, revealed significant upregulation of immune pathway signaling with oral vitamin D₃ but significant downregulation with UVB.Conclusions: Correcting vitamin D deficiency with either oral vitamin D₃ or UVB does not improve the lipid profile. Beyond cholesterol, these 2 modalities of raising 25(OH)D have disparate effects on gene transcription. This trial was registered at clinicaltrials.gov as NCT01688102.

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.

In the Red: Deficits in Immune Regulation Underlie Psoriasis Severity

IL-17-driven pathways are active in the skin of patients with psoriasis. Kim et al. examined lesions from mild and moderate to severe psoriasis and found that differences in cutaneous disease severity may be the outcome of lapses in immunoregulatory mechanisms; because as much, if not more, T helper type 17-induced inflammation was seen in mild psoriasis, these patients may also benefit from anti-IL-17-targeted biologics.