PIM Kinases as Potential Biomarkers and Therapeutic Targets in Inflammatory Arthritides.

The Proviral Integration site for the Moloney murine leukemia virus (PIM)-1 kinase and its family members (PIM-2 and PIM-3) regulate several cellular functions including survival, proliferation, and apoptosis. Recent studies showed their involvement in the pathogenesis of rheumatoid arthritis RA, while no studies are available on psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). The main objective of this study is to assess the expression of PIM kinases in inflammatory arthritides, their correlation with proinflammatory cytokines, and their variation after treatment with biologic disease-modifying anti-rheumatic drugs or JAK inhibitors. We evaluated PIM-1, -2, and -3 expression at the gene and protein level, respectively, in the peripheral blood mononuclear cells and serum of patients with RA, PsA, axSpA, and healthy individuals (CTR). All the samples showed expression of PIM-1, -2, and -3 kinases both at the gene and protein level. PIM-1 was the most expressed protein, PIM-3 the least. PIM kinase levels differed between controls and disease groups, with reduced PIM-1 protein and increased PIM-3 protein in all disease samples compared to controls. No difference was found in the expression of these molecules between the three different pathologies. PIM levels were not modified after 6 months of therapy. In conclusion, our preliminary data suggest a deregulation of the PIM pathway in inflammatory arthritides. In-depth studies on the role of PIM kinases in this field are warranted.

Genetically proxied PCSK9 inhibition is associated with reduced psoriatic arthritis risk.

BACKGROUND: Lipid pathways play a crucial role in psoriatic arthritis development, and some lipid-lowering drugs are believed to have therapeutic benefits due to their anti-inflammatory properties. Traditional observational studies face issues with confounding factors, complicating the interpretation of causality. This study seeks to determine the genetic link between these medications and the risk of psoriatic arthritis. METHODS: This drug target study utilized the Mendelian randomization strategy. We harnessed high-quality data from population-level genome-wide association studies sourced from the UK Biobank and FinnGen databases. The inverse variance-weighted method, complemented by robust pleiotropy methods, was employed. We examined the causal relationships between three lipid-lowering agents and psoriatic arthritis to unveil the underlying mechanisms. RESULTS: A significant association was observed between genetically represented proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition and a decreased risk of psoriatic arthritis (odds ratio [OR]: 0.51; 95% CI 0.14-0.88; P < 0.01). This association was further corroborated in an independent dataset (OR 0.60; 95% CI 0.25-0.94; P = 0.03). Sensitivity analyses affirmed the absence of statistical evidence for pleiotropic or genetic confounding biases. However, no substantial associations were identified for either 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors or Niemann-Pick C1-like 1 inhibitors. CONCLUSIONS: This Mendelian randomization analysis underscores the pivotal role of PCSK9 in the etiology of psoriatic arthritis. Inhibition of PCSK9 is associated with reduced psoriatic arthritis risk, highlighting the potential therapeutic benefits of existing PCSK9 inhibitors.

Rare coding variants in NOX4 link high ROS levels to psoriatic arthritis mutilans.

Psoriatic arthritis mutilans (PAM) is the rarest and most severe form of psoriatic arthritis, characterized by erosions of the small joints and osteolysis leading to joint disruption. Despite its severity, the underlying mechanisms are unknown, and no susceptibility genes have hitherto been identified. We aimed to investigate the genetic basis of PAM by performing massive parallel sequencing in sixty-one patients from the PAM Nordic cohort. We found rare variants in the NADPH oxidase 4 (NOX4) in four patients. In silico predictions show that the identified variants are potentially damaging. NOXs are the only enzymes producing reactive oxygen species (ROS). NOX4 is specifically involved in the differentiation of osteoclasts, the cells implicated in bone resorption. Functional follow-up studies using cell culture, zebrafish models, and measurement of ROS in patients uncovered that these NOX4 variants increase ROS levels both in vitro and in vivo. We propose NOX4 as the first candidate susceptibility gene for PAM. Our study links high levels of ROS caused by NOX4 variants to the development of PAM, offering a potential therapeutic target.

Circulating tRNA-derived fragments are decreased in patients with rheumatoid arthritis and increased in patients with psoriatic arthritis.

INTRODUCTION: tRNA-derived fragments (tRFs) play an important role in immune responses. To clarify the role of tRFs in autoimmunity we studied circulating tRF-levels in patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA), and in a murine model for arthritis. MATERIAL AND METHODS: Circulating tRF-levels were quantified by miR-Q RT-qPCR. tRNA processing and modification enzyme expression was analysed by RT-qPCR and public transcriptomics data. RESULTS: Significant reduction (up to 3-fold on average) of tRF-levels derived from tRNA-Gly-GCC,CCC, tRNA-Glu-CTC and tRNA-Val-CAC,AAC was observed in RA patients, whereas tRNA-Glu-CTC and tRNA-Val-CAC,AAC tRFs were found at significantly higher levels (up to 3-fold on average) in PsA patients, compared to healthy controls. Also in arthritic IL1Ra-KO mice reduced levels of tRNA-Glu-CTC fragments were seen. The expression of NSUN2, a methyltransferase catalysing tRNA methylation, was increased in RA-peripheral blood mononuclear cells (PBMCs) compared to PsA, but this is not consistently supported by public transcriptomics data. DISCUSSION: The observed changes of specific tRF-levels may be involved in the immune responses in RA and PsA and may be applicable as new biomarkers. CONCLUSION: Circulating tRF-levels are decreased in RA and increased in PsA and this may, at least in part, be mediated by methylation changes.

Mendelian randomization analysis reveals causal associations of inflammatory bowel disease with Spondylarthritis.

OBJECTIVE: Inflammatory bowel disease (IBD) is strongly associated with Spondylarthritis (SpA), but the causal relationship remains unclear. This study explores the causal associations between IBD (Crohn's disease [CD] and ulcerative colitis [UC]) and several common subtypes of SpA (Ankylosing Spondylitis [AS], Psoriatic Arthritis [PsA], and Reactive Arthritis [ReA]), using bidirectional two-sample Mendelian randomization (TSMR). METHODS: The causal effects of genetically predicted IBD on AS, PsA, and ReA were firstly investigated in this forward study. The causal effects from AS, PsA, and ReA on IBD were analyzed in the reverse MR. Inverse variance weighted, weighted median, and MR-Egger were applied in the MR analyses. The pleiotropic effects, heterogeneity, and leave-one-out sensitivity analysis were also evaluated. RESULTS: The forward MR analysis demonstrated that IBD increased risk for AS (OR:1.278; P = 1.273 × 10-5), PsA (OR:1.192; P = 1.690 × 10-5), and ReA (OR:1.106; P = 1.524 × 10-3). Among them, CD increased risk of AS (OR:1.196; P = 3.424 × 10-4), PsA (OR:1.101; P = 1.537 × 10-3), ReA (OR:1.079; P = 6.321 × 10-3) whereas UC increased risk of AS (OR:1.166; P = 2.727 × 10-2), PsA (OR:1.110; P = 1.944 × 10-2), and ReA (OR:1.091; P = 1.768 × 10-2). The reverse-direction MR disclosed no notable association; neither was any evidence of pleiotropy detected. CONCLUSION: Our study verifies a causal effect of IBD to AS, PsA as well as ReA, but not vice versa. This might bring new insights for the management of IBD and SpA in clinical practice.

Exploring the causal relationship between inflammatory cytokines and inflammatory arthritis: A Mendelian randomization study.

OBJECTIVES: Previous studies have reported an association between inflammatory cytokines and inflammatory arthritis, including Ankylosing spondylitis (AS), rheumatoid arthritis (RA), and psoriatic arthritis (PsA). This study aims to explore the causal relationship between inflammatory cytokines and AS, RA, and PsA using Mendelian randomization (MR). METHODS: We conducted a bidirectional two-sample MR analysis using genetic summary data from a publicly available genome-wide association study (GWAS) that included 41 genetic variations of inflammatory cytokines, as well as genetic variant data for AS, RA, and PsA from the FinnGen consortium. The main analysis method used was Inverse variance weighted (IVW) to investigate the causal relationship between exposure and outcome. Additionally, other methods such as MR Egger, weighted median (WM), simple mode, and weighted mode were employed to strengthen the final results. Sensitivity analysis was also performed to ensure the reliability of the findings. RESULTS: The results showed that macrophage colony-stimulating factor (MCSF) was associated with an increased risk of AS (OR = 1.163, 95 % CI = 1.016-1.33, p = 0.028). Conversely, high levels of TRAIL and beta nerve growth factor (ß-NGF) were associated with a decreased risk of AS (OR = 0.892, 95 % CI = 0.81-0.982, p = 0.002; OR = 0.829, 95 % CI = 0.696-0.988, p = 0.036). Four inflammatory cytokines were found to be associated with an increased risk of PsA: vascular endothelial growth factor (VEGF) (OR = 1.161, 95 % CI = 1.057-1.275, p = 0.002); Interleukin 12p70 (IL12p70) (OR = 1.189, 95 % CI = 1.049-1.346, p = 0.007); IL10 (OR = 1.216, 95 % CI = 1.024-1.444, p = 0.026); IL13 (OR = 1.159, 95 % CI = 1.05-1.28, p = 0.004). Interleukin 1 receptor antagonist (IL-1rα) was associated with an increased risk of seropositive RA (OR = 1.181, 95 % CI = 1.044-1.336, p = 0.008). Similarly, genetic susceptibility to inflammatory arthritis was found to be causally associated with multiple inflammatory cytokines. Lastly, the sensitivity analysis supported the robustness of these findings. CONCLUSIONS: This study provides additional insights into the relationship between inflammatory cytokines and inflammatory arthritis, and may offer new clues for the etiology, diagnosis, and treatment of inflammatory arthritis.

Molecular profiling of clinical remission in psoriatic arthritis reveals dysregulation of FOS and CCDC50 genes: a gene expression study.

Background: In psoriatic arthritis (PsA), the primary goal of treatment is clinical remission. This study aimed to characterize the molecular profile underlying the induced clinical remission in patients with PsA, comparing the remission state and the healthy condition. Methods: Whole blood transcriptomic analysis was performed on groups of 14 PsA patients in TNFi-induced clinical remission (DAPSA ≤ 4), 14 PsA patients with active disease (DAPSA > 14), and 14 healthy controls (HCs). Then, all differentially expressed genes (DEGs) derived from remission vs. HC comparison were analyzed for functional and biological characteristics by bioinformatics software. The gene expression of 12 genes was then validated by RT-qPCR in an extended cohort of 39 patients in clinical remission, 40 with active disease, and 40 HCs. Results: The transcriptomic analysis of PsA remission vs. HCs highlighted the presence of 125 DEGs, and out of these genes, 24 were coding genes and showed a great involvement in immune system processes and a functional network with significant interactions. The RT-qPCR validation confirming the down- and upregulation of FOS (FC -2.0; p 0.005) and CCDC50 (FC +1.5; p 0.005) genes, respectively, in line with their role in orchestrating inflammation and bone metabolism processes, may be related to PsA pathophysiology. Conclusion: The transcriptomic profile of clinical remission in PsA is similar to a healthy condition, but not identical, differing for the expression of FOS and CCDC50 genes, which appears to play a key role in its achievement.

Multivariate Mendelian randomization provides no evidence for causal associations among both psoriasis and psoriatic arthritis, and skin cancer.

Background: Some retrospective studies reported that psoriasis (PsO) and psoriatic arthritis (PsA) may have been associated with an elevated risk of skin cancer. The causal associations among them remain unclear. Objectives: To evaluate the causal association of among both PsO and PsA, and skin cancer. Methods: We performed large-scale two-sample and Multivariate Mendelian randomization analyses to examine whether there is a causal relationship between PsO and PsA, and skin cancer, encompassing basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and cutaneous melanoma (CM). Results: Genetically predicted PsO, per log-odds ratio increase, showed no significant association with the risk of BCC, cSCC, and CM. The odds ratios (with corresponding 95% confidence intervals) for BCC, cSCC, and CM were 1.00 (0.99,1.01) (PIvw = 0.990), 0.94(0.89, 1.00) (PIvw = 0.065), and 0.99 (0.98, 1.01) (PIvw = 0.239), respectively. PsA showed a significant association with a decreased risk of BCC, with odds ratios (with corresponding 95% confidence intervals) of 1.00 (1.00, 1.00) (PIvw = 0.214) and 1.00 (1.00, 1.00) (PIvw = 0.477), respectively. Univariate analysis of the FinnGen database demonstrated PsA did exhibit a significant association with the decrease risk of BCC, with an odds ratio of 0.94(0.90,0.99) (PIvw = 0.016). However, this association disappeared after other risk factors were adjusted. Conclusions: Our findings suggest no causal association between PsO and PsA and the genetic risk of skin cancer. Further observational studies are required to elucidate the relationship among PsO, PsA, and skin cancer.

The IFIH1/MDA5 rs1990760 Gene Variant (946Thr) Differentiates Early- vs. Late-Onset Skin Disease and Increases the Risk of Arthritis in a Spanish Cohort of Psoriasis.

The melanoma differentiation-associated protein 5 (MDA5; encoded by the IFIH1 gene) mediates the activation of the interferon pathway in response to a viral infection. This protein is also upregulated in autoimmune diseases and psoriasis skin lesions. IFIH1 gene variants that increase MDA5 activity have been associated with an increased risk for immune-mediated diseases, including psoriasis. Our aim is to determine the association between three IFIH1 variants (rs35337543 G/C, intron8 + 1; rs35744605 C/A, Glu627Stop; and rs1990760 C/T, Ala946Thr) and the main clinical findings in a cohort of Spanish patients with psoriasis (N = 572; 77% early-onset). Early-onset psoriasis patients (EOPs) had a significantly higher frequency of severe disease and the Cw6*0602 allele. Carriers of rs1990760 T (946Thr) were more common in the EOPs (p < 0.001), and the effect was more pronounced among Cw6*0602-negatives. This variant was also associated with an increased risk of psoriatic arthritis (PsA) independent from other factors (OR = 1.62, 95%CI = 1.11-2.37). The rs3533754 and rs35744605 polymorphisms did not show significant differences between the two onset age or PsA groups. Compared to the controls, the 946Thr variant was more common in the EOPs (nonsignificant difference) and significantly less common in patients aged >40 years (p = 0.005). In conclusion, the common IFIH1 rs1990760 T allele was significantly more frequent in early-onset compared to late-onset patients. This variant was also an independent risk factor for PsA in our cohort. Our study reinforces the widely reported role of the IFIH1 gene variants on psoriatic disease.

DNA methylation patterns in CD4+ T-cells separate psoriasis patients from healthy controls, and skin psoriasis from psoriatic arthritis.

Background: Psoriasis is an autoimmune/inflammatory disorder primarily affecting the skin. Chronic joint inflammation triggers the diagnosis of psoriatic arthritis (PsA) in approximately one-third of psoriasis patients. Although joint disease typically follows the onset of skin psoriasis, in around 15% of cases it is the initial presentation, which can result in diagnostic delays. The pathophysiological mechanisms underlying psoriasis and PsA are not yet fully understood, but there is evidence pointing towards epigenetic dysregulation involving CD4+ and CD8+ T-cells. Objectives: The aim of this study was to investigate disease-associated DNA methylation patterns in CD4+ T-cells from psoriasis and PsA patients that may represent potential diagnostic and/or prognostic biomarkers. Methods: PBMCs were collected from 12 patients with chronic plaque psoriasis and 8 PsA patients, and 8 healthy controls. CD4+ T-cells were separated through FACS sorting, and DNA methylation profiling was performed (Illumina EPIC850K arrays). Bioinformatic analyses, including gene ontology (GO) and KEGG pathway analysis, were performed using R. To identify genes under the control of interferon (IFN), the Interferome database was consulted, and DNA Methylation Scores were calculated. Results: Numbers and proportions of CD4+ T-cell subsets (naïve, central memory, effector memory, CD45RA re-expressing effector memory cells) did not vary between controls, skin psoriasis and PsA patients. 883 differentially methylated positions (DMPs) affecting 548 genes were identified between controls and "all" psoriasis patients. Principal component and partial least-squares discriminant analysis separated controls from skin psoriasis and PsA patients. GO analysis considering promoter DMPs delivered hypermethylation of genes involved in "regulation of wound healing, spreading of epidermal cells", "negative regulation of cell-substrate junction organization" and "negative regulation of focal adhesion assembly". Comparing controls and "all" psoriasis, a majority of DMPs mapped to IFN-related genes (69.2%). Notably, DNA methylation profiles also distinguished skin psoriasis from PsA patients (2,949 DMPs/1,084 genes) through genes affecting "cAMP-dependent protein kinase inhibitor activity" and "cAMP-dependent protein kinase regulator activity". Treatment with cytokine inhibitors (IL-17/TNF) corrected DNA methylation patterns of IL-17/TNF-associated genes, and methylation scores correlated with skin disease activity scores (PASI). Conclusion: DNA methylation profiles in CD4+ T-cells discriminate between skin psoriasis and PsA. DNA methylation signatures may be applied for quantification of disease activity and patient stratification towards individualized treatment.

Response to anti-IL17 therapy in inflammatory disease is not strongly impacted by genetic background.

Response to the anti-IL17 monoclonal antibody secukinumab is heterogeneous, and not all participants respond to treatment. Understanding whether this heterogeneity is driven by genetic variation is a key aim of pharmacogenetics and could influence precision medicine approaches in inflammatory diseases. Using changes in disease activity scores across 5,218 genotyped individuals from 19 clinical trials across four indications (psoriatic arthritis, psoriasis, ankylosing spondylitis, and rheumatoid arthritis), we tested whether genetics predicted response to secukinumab. We did not find any evidence of association between treatment response and common variants, imputed HLA alleles, polygenic risk scores of disease susceptibility, or cross-disease components of shared genetic risk. This suggests that anti-IL17 therapy is equally effective regardless of an individual's genetic background, a finding that has important implications for future genetic studies of biological therapy response in inflammatory diseases.

Genetic Studies Investigating Susceptibility to Psoriatic Arthritis: A Narrative Review.

PURPOSE: Approximately 30% of patients with psoriasis will develop psoriatic arthritis (PsA), leading to a decreased quality of life for the patient caused by increasing disability and additional health complications. The identification of risk factors for the development of PsA would facilitate the development of risk prediction models in which patients with psoriasis at high risk of developing PsA could be targeted in a stratified medicine approach, enabling early intervention and treatment. PsA is known to have a genetic contribution to susceptibility, and the identification of genetic risk factors that differentiate PsA from cutaneous-only psoriasis is a key area of research. This narrative review summarizes the discovery of genetic risk factors and, with the aid of a primer on risk prediction models, discusses their potential role for the classification of PsA risk and diagnosis. METHODS: All relevant research articles were identified through searches of the PubMed database for literature published up until December 2022. Search terms included psoriatic arthritis, genetic susceptibility, genetic association, genome-wide association study, GWAS, prediction, and polygenic risk score. FINDINGS: The current literature reveals considerable overlap between the genetic susceptibility loci for PsA and psoriasis. Several PsA-specific genetic risk factors have been reported, and most notably these implicate the HLA-B and IL23R genes. Efforts to include genetic risk factors in prediction models for the development of PsA have reported good discrimination. IMPLICATIONS: Key messages emerging from this narrative are as follows: the limited number of PsA-specific susceptibility loci reported to date suggest larger studies are required, facilitated by international collaboration, to achieve the power to detect further genetic factors; the early promising results for genetic-based risk prediction require further validation in independent datasets; and risk prediction models combining clinical and genetic risk factors have yet to be explored.

Insights into suicidal behavior among psoriatic arthritis patients: A systematic review and a genetic linkage disequilibrium analysis.

OBJECTIVES: To systematically assess the magnitude of suicidal behavior among PsA patients and identify associated risk factors. Also identify common genes or coinherited single nucleotide polymorphisms (SNPs) implicated in suicidal behavior and PsA. METHODS: Based on the PRISMA guidelines, we conducted a systematic literature review of the online databases PubMed/Medline, Web of Science, and EMBASE from inception to May 2022. Full-text original articles that describe suicidal behavior in PsA patients were eligible. All registered genome-wide association study (GWAS) data in the GWAS catalog database for PsA and psychiatric traits, such as suicidal behavior, and depression, were downloaded for further analysis. RESULTS: A total of 48 articles were identified, and 6 were relevant to the study question .Among the 122,160 PsA patients, 700 had suicidal behavior (0,57%). The range of age in one study was between 30 and 49 years, and 64% of PsA patients with suicidal behavior were female. Among 13,899 PsA patients 74 had suicidal ideation (0.53%) and 125 suicide attempts occurred (0.9%). In two studies, among 17,383 patients, 13 complete suicides occurred (0.07%). A genetic haplotype on chromosomal region 6p21.1, spanning from 29,597,596 to 32,251,264 Mb, contains predisposing SNPs for PsA and depression. 6p21.1-6p21.3 is the chromosomal region containing the HLA genes of classes I, II and III. CONCLUSION: Suicide behavior in PsA patients was associated with depression and other psychiatric comorbidities. Further evidence supports a genetic origin, at least partly. Awareness of these findings can help clinicians to recognize suicide behavior and prevent suicide attempts.

IL36G genetic variant is independently associated with susceptibility, severity and joint involvement in psoriasis.

Psoriasis (PsO) is a chronic, immune-mediated, inflammatory and polygenic dermatosis associated with both physical and psychological burden that can be triggered by injury, trauma, infections and medications. The etiology of PsO is not fully elucidated but genetic, epigenetic and environmental factors are all likely to play a role. A case-control study was carried out to evaluate the frequency of the IL36G C>T (rs13392494) and the IL36G A>G (rs7584409) variants and their association with susceptibility, joint involvement and severity of PsO. The study included 154 patients with PsO and 154 controls from Brazilian population. The severity of PsO was assessed by the Psoriasis Area and Severity Index (PASI). The IL36G (rs13392494 and rs7584409) variants were genotyped by allelic discrimination assay using the real-time polymerase chain reaction. The association between the IL36G genetic variants and the study variables was analyzed in allelic, dominant, codominant, overdominant, recessive, and haplotype models. The main results were that PsO patients were older (p < 0.001) and had higher body mass index (p < 0.001) than controls; 95.8% of the patients had plaque PsO, 16.1% had psoriatic arthritis (PsA), and 27.9% had PASI > 10. The IL36G rs1339294 variant showed no association with PsO in all genetic models while the IL36G rs7584409 variant showed a protective effect in PsO. However, the G allele of the IL36G rs7584409 in the dominant model was positively associated with PASI > 10 (p = 0.031). Moreover, patients with the GG genotype of the IL36G rs7584409 variant had about 5.0 times more chance of PsA than those with the AA genotype (p = 0.014). Regarding the haplotypes, the C/A in a recessive model (CACA versus C/G and T/A carriers) was associated with PsO (p = 0.035) while the C/G haplotype in a dominant model (C/A carriers versus C/G and T/A carriers) showed a protective effect for PsO (p = 0.041). In conclusion, the G allele of the IL36G rs7584409 variant was associated with protection to PsO; however, in patients with PsO, this same allele was associated with moderate to severe disease and PsA. These results suggest that the IL36G rs7584409 variant may be used as a possible genetic biomarker to predict severity and joint involvement of PsO.

Challenges and opportunities in animal models of psoriatic arthritis.

OBJECTIVE: To review the preparation, characteristics and research progress of different PsA animal models. METHODS: Computerized searches were conducted in CNKI, PubMed and other databases to classify and discuss the relevant studies on PsA animal models. The search keywords were "PsA and animal model(s), PsA and animal(s), PsA and mouse, PsA and mice, PsA and rat(s), PsA and rabbit(s), PsA and dog(s)" RESULTS: The experimental animals currently used to study PsA are mainly rodents, including mice and rats. According to the different methods of preparing the models, the retrieved animal models were classified into spontaneous or genetic mutation, transgenic and induced animal models. These PsA animal models involve multiple pathogenesis, some experimental animals' lesions appear in a short and comprehensive cycle, some have a high success rate in molding, and some are complex and less reproducibility. This article summarizes the preparation methods, advantages and disadvantages of different models. CONCLUSIONS: The animal models of PsA aim to mimic the clinicopathological alterations of PsA patients through gene mutation, transgenesis or targeted proinflammatory factor and to reveal new pathogenic pathways and therapeutic targets by exploring the pathological features and clinical manifestations of the disease. This work will have very far-reaching implications for the in-depth understanding of PsA and the development of new drugs.

Cutaneous lesions in psoriatic arthritis are enriched in chemokine transcriptomic pathways.

OBJECTIVES: Skin from people with psoriasis has been extensively studied and is assumed to be identical to skin from those with psoriatic arthritis (PsA). Chemokines and the CC chemokine scavenger receptor ACKR2 are upregulated in uninvolved psoriasis. ACKR2 has been proposed as a regulator of cutaneous inflammation in psoriasis. The aim of this study was to compare the transcriptome of PsA skin to healthy control (HC) skin and evaluate ACKR2 expression in PsA skin. METHODS: Full-thickness skin biopsies from HC, lesional and uninvolved skin from participants with PsA were sequenced on NovaSeq 6000. Findings were validated using qPCR and RNAscope. RESULTS: Nine HC and nine paired PsA skin samples were sequenced. PsA uninvolved skin was transcriptionally similar to HC skin, and lesional PsA skin was enriched in epidermal and inflammatory genes. Lesional PsA skin was enriched in chemokine-mediated signalling pathways, but uninvolved skin was not. ACKR2 was upregulated in lesional PsA skin but had unchanged expression in uninvolved compared with HC skin. The expression of ACKR2 was confirmed by qPCR, and RNAscope demonstrated strong expression of ACKR2 in the suprabasal layer of the epidermis in PsA lesions. CONCLUSION: Chemokines and their receptors are upregulated in lesional PsA skin but relatively unchanged in uninvolved PsA skin. In contrast to previous psoriasis studies, ACKR2 was not upregulated in uninvolved PsA skin. Further understanding of the chemokine system in PsA may help to explain why inflammation spreads from the skin to the joints in some people with psoriasis.

Associations between family history of psoriatic disease and clinical characteristics on patients with psoriatic arthritis: a nationwide study from the Chinese Registry of Psoriatic Arthritis (CREPAR II).

OBJECTIVES: The study aimed to identify clinical characteristics in Chinese patients with psoriatic arthritis (PsA) with or without a family history of psoriasis and/or PsA. METHODS: Patients with PsA were recruited based on Chinese REgistry of Psoriatic ARthritis (CREPAR) between December 2018 and June 2021. The demographics, clinical information relating to PsA, laboratory variables and comorbidities were collected. The association between family history of psoriatic disease and clinical characteristics on PsA was analysed using logistic regression analysis. RESULTS: Among 1074 eligible patients with PsA, 313 (29.1%) had a family history of psoriasis and/or PsA. Compared with patients without a family history, notably, patients with a family history of psoriasis and/or PsA had an earlier age of onset of psoriasis and PsA, higher proportions of enthesitis and nail involvement, a higher prevalence of positive human leukocyte antigen-B27 (HLA-B27), lower disease activity score 28-erythrocyte sedimentation rate, higher proportions of hyperlipidaemia, lower proportions of hypertension and diabetes. Furthermore, after adjusting for confounding factors, logistic regression analysis demonstrated that a positive family history of psoriasis and/or PsA was associated with more females (OR 1.514, 95% CI 1.088-2.108, p=0.014), earlier age at psoriasis onset (OR 0.971, 95%CI 0.955-0.988, p=0.001), a higher prevalence of HLA-B27 (OR 1.625 95%CI 1.089-2.426, p=0.018), more presence of nail involvement (OR 1.424, 95%CI 1.007-2.013, p=0.046) and enthesitis (OR 1.393, 95%CI 1.005-1.930, p=0.046), a higher proportion of hyperlipidaemia (OR 2.550, 95%CI 1.506-4.317, p=0.001) in PsA patients. CONCLUSIONS: This was first nationwide study to characterize patients with and without a family history of psoriatic disease in China. The findings from the present study revealed that family history of psoriasis and/or PsA had greater effects on disease phenotypes of PsA, especially nail disease and enthesitis.

Discovery of CLEC2B as a diagnostic biomarker and screening of celastrol as a candidate drug for psoriatic arthritis through bioinformatics analysis.

BACKGROUND: Psoriatic arthritis (PSA) is a chronic, immune-mediated inflammatory joint disease that is liked to mortality due to cardiovascular disease. Diagnostic markers and effective therapeutic options for PSA remain limited due to the lack of understanding of the pathogenesis. We aimed to identify potential diagnostic markers and screen the therapeutic compounds for PSA based on bioinformatics analysis. METHODS: Differentially expressed genes (DEGs) of PSA were identified from the GSE61281 dataset. WGCNA was used to identify PSA-related modules and prognostic biomarkers. Clinical samples were collected to validate the expression of the diagnostic gene. These DEGs were subjected to the CMap database for the identification of therapeutic candidates for PSA. Potential pathways and targets for drug candidates to treat PSA were predicted using Network Pharmacology. Molecular docking techniques were used to validate key targets. RESULTS: CLEC2B was identified as a diagnostic marker for PSA patients (AUC > 0.8) and was significantly upregulated in blood samples. In addition, celastrol was identified as a candidate drug for PSA. Subsequently, the network pharmacology approach identified four core targets (IL6, TNF, GAPDH, and AKT1) of celastrol and revealed that celastrol could treat PSA by modulating inflammatory-related pathways. Finally, molecular docking demonstrated stable binding of celastrol to four core targets in the treatment of PSA. Animal experiments indicated celastrol alleviated inflammatory response in the mannan-induced PSA. CONCLUSION: CLEC2B was a diagnostic marker for PSA patients. Celastrol was identified as a potential therapeutic drug for PSA via regulating immunity and inflammation.

Body Mass Index and the Risk of Rheumatic Disease: Linear and Nonlinear Mendelian Randomization Analyses.

OBJECTIVE: Although the association between obesity and risk of rheumatic disease is well established, the precise causal relation has not been conclusively proven. Here, we estimate the causal effect of body mass index (BMI) on the risk of developing 5 different rheumatic diseases. METHODS: Linear and nonlinear mendelian randomization (MR) were used to estimate the effect of BMI on risk of rheumatic disease, and sex-specific effects were identified. Analyses were performed in 361,952 participants from the UK Biobank cohort for 5 rheumatic diseases: rheumatoid arthritis (n = 8,381 cases), osteoarthritis (n = 87,430), psoriatic arthropathy (n = 933), gout (n = 13,638), and inflammatory spondylitis (n = 4,328). RESULTS: Using linear MR, we found that 1 SD increase in BMI increases the incidence rate for rheumatoid arthritis (incidence rate ratio [IRR] 1.52 [95% confidence interval (95% CI) 1.36-1.69]), osteoarthritis (IRR 1.49 [95% CI 1.43-1.55]), psoriatic arthropathy (IRR 1.80 [95% CI 1.31-2.48]), gout (IRR 1.73 [95% CI 1.56-1.92]), and inflammatory spondylitis (IRR 1.34 [95% CI 1.14-1.57]) in all individuals. BMI was found to be a stronger risk factor in women compared to men for psoriatic arthropathy (P for sex interaction = 3.3 × 10-4 ) and gout (P for sex interaction = 4.3 × 10-3 ), and the effect on osteoarthritis was stronger in premenopausal compared to postmenopausal women (P = 1.8 × 10-3 ). Nonlinear effects of BMI were identified for osteoarthritis and gout in men, and for gout in women. The nonlinearity for gout was also more extreme in men compared to women (P = 0.03). CONCLUSION: Higher BMI causes an increased risk for rheumatic disease, an effect that is more pronounced in women for both gout and psoriatic arthropathy. The novel sex- and BMI-specific causal effects identified here provide further insight into rheumatic disease etiology and mark an important step toward personalized medicine.

Evidence for a causal association between psoriasis and psychiatric disorders using a bidirectional Mendelian randomization analysis in up to 902,341 individuals.

BACKGROUND: The causal association between psoriasis and psychiatric disorders remains ambiguous. OBJECTIVES: This study aimed to investigate the causal relationship between psoriasis and common psychiatric disorders using bidirectional Mendelian randomization (MR) analysis. METHODS: Major depressive disorder (MDD) (N = 217,584), bipolar disorder (N = 51,710), schizophrenia (N = 77,096), and anxiety disorder (N = 218,792) were obtained as outcomes, and psoriasis (N = 337,159) were as exposure. Inverse variance weighting (IVW) was used as the main method, with other sensitivity methods as auxiliary methods. Sensitivity analysis and heterogeneity tests were performed to ensure the robustness of the results. We also performed a subgroup analysis of cases with psoriatic arthritis (PsA) (N = 213,879) by using the same testing methods. RESULTS: MR showed that the genetic risk of psoriasis was positively associated with bipolar disorder (odds ratio (OR) = 13.54, 95 % confidence interval (95%CI): 2.43-75.37, P = 0.002) and MDD (OR = 1.08, 95%CI: 1.01-1.15, P = 0.027), which indicated possible causal relationships between psoriasis and these two diseases. Schizophrenia (OR = 3.52, 95%CI: 0.22-55.71, P = 0.372) and anxiety disorders (OR = 0.65, 95%CI: 0.16-2.63, P = 0.546) indicated no significant causal association. No reverse causal effects of psychiatric disorders on psoriasis were found. Subgroup analysis also suggested causal association of PsA with the bipolar affective disorder (OR = 1.05, 95%CI: 1.01-1.08, P = 0.005). LIMITATIONS: Potential pleiotropic effects, restriction to European populations, and differences in diagnostic criteria. CONCLUSIONS: This study has supported the causal association of psoriasis with MDD and bipolar disorder, and the subtype PsA with bipolar disorder, which informed the intervention for mental illnesses in patients with psoriasis.