Certain class I HLA alleles and haplotypes implicated in susceptibility play a role in determining specific features of the psoriatic arthritis phenotype

Prevention of Psoriatic Arthritis: The Need for Prospective Studies

Psoriatic arthritis (PsA) is a systemic chronic inflammatory disease that develops in up to 30% of patients with psoriasis. Mixed data variably support the potential ability to "prevent" and/or delay PsA through use of systemic therapies in psoriasis patients. Though intriguing, almost all of these studies are retrospective in nature, and hold substantial limitations and potential biases that challenge the ability to meaningfully interpretation their results. Thus, the authors believe prospective observational and interventional studies are crucial to understanding our ability to truly modify the transition from psoriasis to psoriatic arthritis and delay or prevent PsA onset.

Upadacitinib for axial spondyloarthritis: a meta-analysis of efficacy and safety

To explore the effectiveness and safety of upadacitinib for managing axial spondyloarthritis. Four databases (PubMed, EMBASE, Cochrane, and Web of Science) were applied to search randomized controlled trials (RCTs) for assessing upadacitinib treatment for axial spondyloarthritis published until January 2024. Five RCTs involving 1,246 participants were included. The upadacitinib group had significantly higher percentages of participants achieving Assessment of spondyloarthritis international society (ASAS) 20, ASAS40, ASAS partial remission, Bath ankylosing spondylitis disease activity index (BASDAI) 50, Ankylosing Spondylitis Disease Activity Score (ASDAS) low disease activity, ASDAS inactive disease, ASDAS clinically important improvement, and ASDAS major improvement, except for Work Productivity and Activity Impairment (WPAI) absenteeism. Obvious improvements were observed in the upadacitinib group for ASDAS (CRP), BASDAI, Modified BASDAI, Bath Ankylosing Spondylitis Functional Index (BASFI), Canadian Spondyloarthritis Research Consortium (SPARCC) MRI spine, SPARCC MRI sacroiliac joint, Ankylosing Spondylitis Quality of Life (ASQoLS), ASAS Health Index, Bath Ankylosing Spondylitis Metrology Index (BASMI), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), Total Back Pain, Nocturnal Back Pain, WPAI overall work impairment, WPAI presenteeism, and WPAI activity impairment. Adverse events (AEs) and serious adverse events (SAEs) incidence rates showed no significant difference differ between upadacitinib and placebo groups. Subgroup analysis revealed that disease subtype and age did not significantly affect efficacy, and upadacitinib demonstrated comparable efficacy to adalimumab for axial spondyloarthritis. Upadacitinib exhibited satisfactory efficacy in treating axial spondyloarthritis, reducing disease activity and significantly enhancing patients' physical function, emotional well-being, and social engagement. This meta-analysis offers robust evidence supporting upadacitinib as a new treatment for axial spondyloarthritis patients.

Association between enthesitis/dactylitis resolution and patient-reported outcomes in guselkumab-treated patients with psoriatic arthritis

OBJECTIVES

To evaluate the association between enthesitis resolution (ER) and dactylitis resolution (DR) and meaningful improvements in patient-reported outcomes (PROs) among biologic-naïve patients with PsA receiving guselkumab in the DISCOVER-2 study.

METHODS

Enthesitis and dactylitis, characteristic lesions of PsA, were evaluated by independent assessors using the Leeds Enthesitis Index (range, 0-6) and Dactylitis Severity Score (range, 0-60). Proportions of patients with ER or DR (score = 0) among those with score > 0 at baseline were determined at weeks 24, 52, and 100. PROs included: fatigue (Functional Assessment of Chronic Illness Therapy-Fatigue [FACIT-Fatigue]), pain (0-100 visual analog scale), physical function (Health Assessment Questionnaire-Disability Index [HAQ-DI]), and health-related quality of life (36-item Short-Form Health Survey physical/mental component summary [SF-36 PCS/MCS]). Meaningful responses were defined as: improvements of ≥ 4 for FACIT-Fatigue, ≥ 0.35 for HAQ-DI, and ≥ 5 for SF-36 PCS/MCS and absolute scores of ≤ 15 for minimal pain and ≤ 0.5 for normalized HAQ-DI. Associations between ER/DR status and PRO response status were tested using a Chi-square test.

RESULTS

Guselkumab-treated patients with ER were more likely than those without ER to achieve minimal pain (p < 0.001), normalized HAQ-DI (p < 0.001), and PCS response (p < 0.05) at weeks 24, 52, and 100. Patients with DR were more likely than those without DR to achieve FACIT-Fatigue response at week 24 and week 52 (both p ≤ 0.01) and minimal pain at week 24 and normalized HAQ-DI at week 52 (both p ≤ 0.03).

CONCLUSION

In biologic-naïve patients with active PsA treated with guselkumab, achieving ER or DR was associated with durable improvements in selected PROs, including those of high importance to patients.

TRIAL REGISTRATION

ClinicalTrials.gov ( https://clinicaltrials.gov ) NCT03158285; Registered: May 16, 2017. Key Points • At week 100, 65% and 76% of guselkumab-treated patients achieved enthesitis and dactylitis resolution (ER/DR). • Achieving ER was associated with achieving DR and vice versa through the end of study. • Achieving ER or DR was associated with durable and meaningful improvements in selected patient-reported outcomes.

Identification of autoantibodies against PsoP27 in synovial fluid derived from psoriatic arthritis and rheumatoid arthritis patients

PsoP27 is an antigen expressed in psoriatic lesions. It plays an inflammatory role in psoriasis. This study objective was to characterize antibodies (Abs) against PsoP27 in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA). Levels of Abs against native and citrullinated PsoP27 in PsA and RA patients' synovial fluid (SF) and sera were determined by ELISA. SF of osteoarthritis (OA) patients and sera of healthy donors were used as controls. Levels of Abs against PsoP27 were correlated with disease activity scores. Abs against native and citrullinated PsoP27 levels in SF of PsA (n = 48; 0.38 ± 0.03 and 0.44 ± 0.04, respectively) and RA (n = 22; 0.57 ± 0.1 and 0.62 ± 0.09, respectively) were significantly higher than in OA patients (n = 23; 0.14 ± 0.01 and 0.15 ± 0.01, respectively) (p < .0001). For both Abs, there were no significant differences between their level in PsA and RA patients. There was no difference in the level of Abs against citrullinated PsoP27 in SF of seronegative versus seropositive RA patients. Levels of Abs against both native and citrullinated PsoP27 in the SF and level of systemic C-reactive protein in PsA correlated positively, while in RA there were no significant correlations with disease activity scores. No differences in level of Abs against PsoP27 were found in the sera of all three study groups. Abs against native and citrullinated PsoP27 are present in PsA and RA SF but not in those of OA patients, suggesting a potential role of those Abs in inflammatory joint diseases.

The thiol/disulfide balance is shifted towards oxidation in psoriatic arthritis compared to controls and is associated with higher disease activity

OBJECTIVE

This study was designed to compare thiol/disulfide and ischemia-modified albumin (IMA) levels between psoriatic arthritis (PsA) and healthy controls and evaluate the correlation between these molecules and the disease activity scores used in PsA.

METHODS

A total of 63 PsA patients and 49 healthy volunteers were included in the study. Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), modified disease activity score 28 (DAS28), and Bath Ankylosing Spondylitis Functional Index (BASFI) scores were used as disease activity indices for PsA patients. Calculations of native thiol (-SH), disulfide (-SS), and total thiol (-SH+-SS) molecules were made by the automatic spectrophotometric method, and the albumin cobalt binding test was used to measure IMA levels.

RESULTS

In the PsA group, -SS/-SH and -SS/(-SH+-SS) levels were higher and -SH/(-SH+-SS) levels were lower than in controls. In the linear regression analysis, a significant correlation relationship was detected between DAS28-erythrocyte sedimentation rate (ESR) and -SS/(-SH+-SS) (β = 0.795, CI 95%, 0.196-1.395; P = .010), -SH/(-SH+-SS) (β = -0.475, CI 95%, 0.114-0.836; P = .010) and IMA (β = 3.932, CI 95%, 0.859-7.005; P = .013). Additionally, a significant correlation was detected between IMA and BASDAI and BASFI.

CONCLUSION

In PsA, thiol/disulfide homeostasis has shifted in favor of disulfide as an oxidative indicator. Serum thiol/disulfide levels are correlated with PsA disease activity indices.

Serum proteome analysis identifies a potential biomarker for axial psoriatic arthritis

BACKGROUND

To identify potential serum biomarkers for differentiating between axial psoriatic arthritis (axPsA) and peripheral psoriatic arthritis (pPsA).

METHODS

Serum samples were collected from patients with PsA to create a biomarker discovery cohort and a verification cohort. Patients with PsA were classified into axial or peripheral subtypes based on imaging criteria. Untargeted proteomics technology was used in the discovery phase to screen for biomarkers, and candidate biomarkers were evaluated using enzyme-linked immunosorbent assay (ELISA) in the verification phase.

RESULTS

We identified 45 significantly differentially expressed proteins (DEPs) between axPsA (n = 20) and pPsA (n = 20) with liquid chromatography-mass spectrometry. Among these DEPs, serum pigment epithelium-derived factor (PEDF) was identified as a candidate biomarker using the Boruta algorithm and lasso regression. Results of ELISA further confirmed that the level of serum PEDF expression was significantly higher in axPsA (n = 37) than in pPsA (n = 51) at the verification cohort (37.9 ± 10.1 vs. 30.5 ± 8.9 μg/mL, p < 0.001). Receiver operating characteristics analysis showed that PEDF had an area under the curve (AUC) of 0.72. Serum PEDF was positively correlated with body mass index and C-reactive protein. Additionally, there was a tendency towards a positive correlation between PEDF and the Bath Ankylosing Spondylitis Disease Activity Index.

CONCLUSIONS

This study provided a comprehensive characterization of the proteome in axPsA and pPsA and identified a candidate biomarker, PEDF, that may contribute to early diagnosis for axPsA.

The Interleukine-17 Cytokine Family: Role in Development and Progression of Spondyloarthritis, Current and Potential Therapeutic Inhibitors

Spondyloarthritis (SpA) encompasses a group of chronic inflammatory rheumatic diseases with a predilection for the spinal and sacroiliac joints, which include axial spondyloarthritis, psoriatic arthritis, reactive arthritis, arthritis associated with chronic inflammatory bowel disease, and undifferentiated spondyloarthritis. The prevalence of SpA in the population varies from 0.5 to 2%, most commonly affecting young people. Spondyloarthritis pathogenesis is related to the hyperproduction of proinflammatory cytokines (TNFα, IL-17A, IL-23, etc.). IL-17A plays a key role in the pathogenesis of spondyloarthritis (inflammation maintenance, syndesmophites formation and radiographic progression, enthesites and anterior uveitis development, etc.). Targeted anti-IL17 therapies have established themselves as the most efficient therapies in SpA treatment. The present review summarizes literature data on the role of the IL-17 family in the pathogenesis of SpA and analyzes existing therapeutic strategies for IL-17 suppression with monoclonal antibodies and Janus kinase inhibitors. We also consider alternative targeted strategies, such as the use of other small-molecule inhibitors, therapeutic nucleic acids, or affibodies. We discuss advantages and pitfalls of these approaches and the future prospects of each method.

Targeted Therapies in Psoriatic Arthritis—An Update

Psoriatic arthritis (PsA) is a systemic inflammatory condition characterised by multiple clinical manifestations. Over the last decade, significant progress has been made in understanding the pathobiology of the disease. An expanded set of targeted therapies have emerged and have shown efficacy in PsA. Nevertheless, there is still a substantial subset of patients who experience no response or only a partial response to currently licensed therapies. The heterogeneous nature of the disease, together with a varying level of severity at presentation and disease activity during follow-up, brings tremendous challenges to devising management strategies. While there are certain pathophysiological similarities between PsA and rheumatoid arthritis (RA), it has become clear that there are discriminating features between these two conditions at the clinical, cellular, and molecular levels. However, there is a degree of overlap in the clinical approach when treating both PsA and RA, given that many biological and targeted therapies have proven efficacy for both pathologies. With an increasing understanding of the relevance of the IL-23/IL-17 axis in PsA, pharmacological agents blocking this pathway have provided promising possibilities for patients with PsA.

Phenotypic heterogeneity in psoriatic arthritis: towards tissue pathology-based therapy

Psoriatic arthritis (PsA) is a heterogeneous disease involving multiple potential tissue domains. Most outcome measures used so far in randomized clinical trials do not sufficiently reflect this domain heterogeneity. The concept that pathogenetic mechanisms might vary across tissues within a single disease, underpinning such phenotype diversity, could explain tissue-distinct levels of response to different therapies. In this Review, we discuss the tissue, cellular and molecular mechanisms that drive clinical heterogeneity in PsA phenotypes, and detail existing tissue-based research, including data generated using sophisticated interrogative technologies with single-cell precision. Finally, we discuss how these elements support the need for tissue-based therapy in PsA in the context of existing and new therapeutic modes of action, and the implications for future PsA trial outcomes and design.

Peripheral spondyloarthritis and psoriatic arthritissine psoriase: are we dealing with semantics or clinically meaningful differences?

Diagnosing peripheral spondyloarthritis (pSpA) remains a significant challenge due to the lack of specific disease biomarkers and the overlap with other SpA subtypes, mainly psoriatic arthritis (PsA), which represents a diagnostic challenge particularly in the absence of skin psoriasis (PsAsine psoriase). This narrative review aimed to compare the epidemiology, genetic susceptibility, pathophysiology, classification criteria, disease phenotype and burden, and therapeutic guidelines between patients diagnosed with pSpA and those with PsAsine psoriase,to determine if the two entities should be considered jointly or distinctly. Globally, pSpA appears to be more inclusive compared with PsAsine psoriase. Areas of similarities include age of onset, number of joints involved and prevalence of axial involvement. However, patients with pSpA have a male gender predominance, a higher prevalence of HLA-B27, enthesitis and involvement of large joints of the lower limbs, whereas patients with PsAsine psoriasehave a higher prevalence HLA-Cw6, dactylitis and involvement of hand distal interphalangeal joints. Therefore, the difference between pSpA and PsAsine psoriasegoes beyond semantics. The few dissimilarities should drive scientific efforts to reach a better characterisation of pSpA as an individual disease. Accordingly, randomised clinical trials should target patients with well-defined pSpA to identify effective therapies in this population.

HLA-B27 and its role of the pathogenesis of psoriatic arthritis

The literature review presents the characteristics of the human leukocyte antigen (HLA)-B27 as a factor contributing to the development of psoriatic arthritis. HLA-B27 is a class I surface antigen encoded by the major histocompatibility complex (MHC) B locus located on chromosome 6. The main function is to present antigenic peptides to the CD8+ T-cells. HLA-B27 is the most important genetic biomarker for psoriatic arthritis, as it provides phenotypic differentiation in the patient population. The prevalence of HLA-B27 in various population groups are presented. The structural features of the HLA-B27 molecule are described. The characteristics of methods for detecting HLA-B27 status and determining its subtypes are given. The main mechanisms of the HLA-B27 polymorphism influence on the development of psoriatic arthritis are considered, and hypotheses are analyzed that explain the pathogenic effect of HLA-B27: the arthritogenic peptide hypothesis, the misfolding hypothesis, the HLA-B27 heavy chain homodimer formation hypothesis. The features of the clinical manifestations and course of HLA-B27-positive psoriatic arthritis are presented, allowing the use of HLA-B27 to predict the development of psoriatic joint damage.

Identification of variants in genes associated with autoinflammatory disorders in a cohort of patients with psoriatic arthritis

Objectives

Besides adaptive immunity genes, genetic risk factors for psoriatic arthritis (PsA) include innate immunity loci, which suggests an autoinflammatory disease mechanism, at least in a subset of patients. Here, we aimed at investigating the autoinflammatory genetic background of PsA.

Methods

A total of 120 patients with PsA visiting the outpatient clinics of the Hannover University hospital underwent targeted next-generation sequencing, searching for variations in genes linked with inborn errors of immunity classified as autoinflammatory disorders (AIDs). Deleteriousness of rare variants was evaluated through in silico analysis.

Results

We found 45 rare predicted deleterious variants in 37 out of 120 (30.8%) patients with PsA. Relatively common were variants in AP1S3, PLCG2, NOD2 and NLRP12. All 45 variants were monoallelic and 25 of them, identified in 20 out of 120 (16.7%) patients, were localised in genes associated with autosomal dominant (AD) disorders. Detection of those variants is associated with pustular psoriasis or a coexisting inflammatory bowel disease (IBD).

Conclusions

Approximately 30% of patients with PsA harboured at least one variant in a gene associated with an AID, suggesting an autoinflammatory disease mechanism. Detection of variants in genes linked to AD-AIDs may explain extra-articular manifestations of PsA, such as pustular psoriasis and IBD.

Etiopathogenesis of Psoriasis from Genetic Perspective: An updated Review

Psoriasis is an organ-specific autoimmune disease characterized by the aberrant proliferation and differentiation of keratinocytes, leading to skin lesions. Abnormal immune responses mediated by T cells and dendritic cells and increased production of inflammatory cytokines have been suggested as underlying mechanisms in the pathogenesis of psoriasis. Emerging evidence suggests that there is a heritable basis for psoriatic disorders. Moreover, numerous gene variations have been associated with the disease risk, particularly those in innate and adaptive immune responses and antigen presentation pathways. Herein, this article discusses the genetic implications of psoriatic diseases' etiopathogenesis to develop novel investigative and management options.

Exploring the Association Between History of Psoriasis (PSO) and Disease Activity in Patients with Psoriatic Arthritis (PsA)

Introduction

Psoriatic arthritis (PsA) is a common inflammatory disease affecting the peripheral and axial skeleton. History of psoriasis (PSO), either personal or family history, is an important factor in the diagnosis of PsA. We investigated the association between history of PSO and clinical characteristics of PsA.

Methods

PsA patients were consecutive recruited from 2019 to 2020. These patients were subjected to clinical, biochemical, and radiographic examinations, and disease activity was evaluated. Continuous and categorical variables analyses were presented.

Results

All registered patients (296 cases) met the classification criteria of PsA. They were divided into three groups based on the history of psoriasis (PSO), as: (1) 145 patients with PSO themselves (pPsA); (2) 96 patients with family history of PSO (fPsA); (3) 55 patients with family history and coexisting PSO themselves (fPsA/PSO). Compared to fPsA/PSO, the levels of CRP, ESR, uric acid, DAPSA, BASDAI, ASDAS, and BASFI were lower in fPsA, but similar to pPsA. The severity of sacroiliitis tended to be more severe in fPsA/PSO than fPsA (OR_{2 vs. 3} 0.508; 95% CI 0.272 to 0.949, p < 0.05). No significant differences were found in HLA-B-27 and common inflammatory articular and extra-articular manifestations among the three groups. Furthermore, there were no differences in LEI, TJC, SJC, and DAS28_CRP. Interestingly, a correlation was found between the ages of individuals with PSO and the onset of arthritis, and the earliest arthritis onset occurred in fPsA/PSO patients (p < 0.001).

Conclusions

Our study demonstrates that currently existing cutaneous lesions in patients themselves are correlated with disease activity and severity of axial joint damage, whereas family history does not have an evident impact on the disease activity of PsA.

Psoriatic arthritis from a mechanistic perspective

Psoriatic arthritis (PsA) is part of a group of closely related clinical phenotypes ('psoriatic disease') that is defined by shared molecular pathogenesis resulting in excessive, prolonged inflammation in the various tissues affected, such as the skin, the entheses or the joints. Psoriatic disease comprises a set of specific drivers that promote an aberrant immune response and the consequent development of chronic disease that necessitates therapeutic intervention. These drivers include genetic, biomechanical, metabolic and microbial factors that facilitate a robust and continuous mobilization, trafficking and homing of immune cells into the target tissues. The role of genetic variants involved in the immune response, the contribution of mechanical factors triggering an exaggerated inflammatory response (mechanoinflammation), the impact of adipose tissue and altered lipid metabolism and the influence of intestinal dysbiosis in the disease process are discussed. Furthermore, the role of key cytokines, such as IL-23, IL-17 and TNF, in orchestrating the various phases of the inflammatory disease process and as therapeutic targets in PsA is reviewed. Finally, the nature and the mechanisms of inflammatory tissue responses inherent to PsA are summarized.

Dactylitis is associated with more severe axial joint damage and higher disease activity in axial psoriatic arthritis

Objective

To investigate the association of dactylitis with disease activity and the severity of radiological damage in patients with axial psoriatic arthritis (AxPsA).

Methods

Patients with AxPsA met the classification criteria (CASPAR) were recruited. Clinical data, radiographic changes and disease activity in AxPsA patients with or without dactylitis were compared using t-tests, Mann-Whitney U test or Kruskal-Wallis test for continuous variables, Ⲭ2 or Fisher exact tests for categorical variables and logistic regression analysis for the association between dactylitis and radiographic damage.

Results

A total of 186 AxPsA patients were analysed and dichotomized by the presence or absence of dactylitis. Patients with dactylitis had higher levels of CRP, ESR, NLR and PLR than those who did not have (PCRP=0.004; PESR=0.006; PNLR=0.035; PPLR=0.020). In addition, dactylitic AxPsA patients also had higher TJC, SJC, DAPSA and HAQ (P<0.001), and higher score of DAS28, ASDAS, BASFI and BASDAI (P<0.05), while less patients met MDA and DAPSA-LDA criteria (P<0.05). Consistently, they had more severe radiological damage (P< 0.05), higher sacroiliac scores (OR 2.076, 95%CI 1.137 to 3.791, P=0.017) and more significant reduction in BMD (OR 2.422, 95%CI 1.342 to 4.372, P=0.003). No statistical differences were observed for HLA-B27 and LEI between these two group patients. Notably, only half of dactylitic AxPsA patients had inflammatory back pain.

Conclusion

Our study demonstrated that dactylitic AxPsA patients had higher disease activity and more severe joint damage compared those without dactylitis. Careful examination of axial involvements and proper management are recommended.

Defining imaging sub-phenotypes of psoriatic arthritis: integrative analysis of imaging data and gene expression in a PsA patient cohort

OBJECTIVES

To define imaging sub-phenotypes in patients with PsA; determine their association with whole blood gene expression and identify biological pathways characterizing the sub-phenotypes.

METHODS

Fifty-five patients with PsA ready to initiate treatment for active disease were prospectively recruited. We performed musculoskeletal ultrasound assessment of the extent of inflammation in the following domains: synovitis, peritenonitis, tenosynovitis and enthesitis. Peripheral whole blood was profiled with RNAseq, and gene expression data were obtained. First, unsupervised cluster analysis was performed to define imaging sub-phenotypes that reflected the predominant tissue involved. Subsequently, principal component analysis was used to determine the association between imaging-defined sub-phenotypes and peripheral blood gene expression profile. Pathway enrichment analysis was performed to identify underlying mechanisms that characterize individual sub-phenotypes.

RESULTS

Cluster analysis revealed three imaging sub-phenotypes: (i) synovitis predominant [n = 31 (56%)]; (ii) enthesitis predominant [n = 13 (24%)]; (iii) peritenonitis predominant [n = 11 (20%)]. The peritenonitis-predominant sub-phenotype had the most severe clinical joint involvement, whereas the enthesitis-predominant sub-phenotype had the highest tender entheseal count. Unsupervised clustering of gene expression data identified three sub-phenotypes that partially overlapped with the imaging sub-phenotypes suggesting biological and clinical relevance of these sub-phenotypes. We therefore characterized enriched differential pathways, which included: immune system (innate system, B cells and neutrophil degranulation), complement system, platelet activation and coagulation function.

CONCLUSIONS

We identified three sub-phenotypes based on the predominant tissue involved in patients with active PsA. Distinct biological pathways may underlie these imaging sub-phenotypes seen in PsA, suggesting their biological and clinical importance.

The Role of Interleukin-23 Inhibition in the Treatment of Psoriatic Arthritis

Psoriatic arthritis is a chronic inflammatory autoimmune disease with varied manifestations, including functional limitation and reduced quality of life. Improved understanding of the immunopathogenesis of psoriatic arthritis, particularly the role of the interleukin-23 and interleukin-17 axis, has led to the development of therapeutic targets to alter the natural history of the condition. In this article, we review the role of monoclonal antibodies targeting the p19 subunit of interleukin-23 in the treatment of psoriatic arthritis.

Genetic markers for psoriatic arthritis among patients with psoriasis. Part II: HLA genes

Psoriatic arthritis often leads to the development of severe outcomes ankylosis, deformities of the affected joints with severe impairment of their functions and disability. Early identification of patients with psoriasis with an increased risk of developing psoriatic arthritis for the purpose of its timely diagnosis and early initiation of therapy can prevent the development of severe disease outcomes. It is believed that the genes of the HLA system make the greatest individual genetic contribution to the formation of a predisposition to hereditary diseases with polygenic inheritance. The literature review considers the polymorphisms of the genes of the HLA system, associated with the development of psoriatic arthritis, in patients with psoriasis. The HLA alleles that contribute to the development of psoriatic arthritis and its individual forms have been identified. HLA alleles have been identified, which have a protective effect against the development of psoriatic arthritis.

Exploring the Diverse Immune and Genetic Landscape of Psoriatic Arthritis

Psoriatic arthritis (PsA) is characterized by delays in diagnosis and modest effect of treatment in terms of joint response. An understanding of molecular pathomechanisms may aid in developing diagnostic and prognostic models. Genetic susceptibility (e.g., HLA class I genes, IL-23-related genes) can be responsible for the pattern of psoriatic manifestations and affinity for tissue involvement. Gene expression analysis indicates an inflammatory profile that is distinct for PsA, but disparate across tissues. This has clinical implications, as for example, dual blockade of IL-17A and IL-17F can lead to superior clinical effects if there is differential expression of IL-17 receptors in tissues. Structural and functional impairment of barrier tissue, including host-microbiome interactions, may be the source of immune activation. Interplay between different cell populations of innate and adaptive immunity is emerging, potentially providing a link between the transition of skin-to-joint disease. Th17 subsets, IL-17A, IL-17F and IL-23 are crucial in PsA pathogenesis, with both clinical and experimental evidence suggesting a differential molecular landscape in cutaneous and articular compartments.

Advanced genomics and clinical phenotypes in psoriatic arthritis

Psoriatic Arthritis (PsA) is a complex polygenic inflammatory disease showing a variable musculoskeletal involvement in patients with skin psoriasis. PsA coexist in 25-40 % of patients with the dermatological manifestations, but PsA may also predate the appearance of psoriasis. Nonetheless, the immunopathogenesis of psoriasis and PsA manifest significant similarities, with a major role of the individual susceptibility in both cases. Genome wide association studies (GWAS) identified several genes/loci associated with the risk to develop PsA, both dependent and independent of psoriasis. The major challenge is thus represented by the need to translate the identification of functional polymorphisms and other genetics findings into biological mechanisms along with the identification of novel putative drug targets. A functional genomics approach aims to increase GWAS power and recent evidence supports the use of a multilayer process, including eQTL, methylome, chromatin conformation analysis and genome editing to discover novel genes that can be affected by disease-associated variants, such as PsA. The available data have considered PsA as a unique homogeneous clinical entity while the clinical experience supports a wide variability of skin and joint manifestations coexisting in diverse patients with different mechanisms underlying the musculoskeletal and dermatological domains. A better discrimination of the patient features is encouraged by the limited data on functional genomics. We provide herein a review of the latest findings on PsA functional genomics highlighting the exciting developments in the field and how these might lead to a better understanding of gene regulation underpinning disease mechanisms and ultimately refine clinical phenotyping.

Psoriasis and Imaging Progression in early Axial Spondyloarthritis: Results from a 48-month follow-up (Italian arm of SPACE study)

OBJECTIVES

To assess the influence of psoriasis on spinal/pelvic radiographic progression and magnetic resonance imaging (MRI) features in early-stage axial spondyloarthritis (axSpA).

METHODS

Analysis of baseline data from the Italian SPACE cohort, including patients with chronic-back-pain (CBP; duration ≥ 3 months and ≤2 years; onset <45 years) was performed. Patients underwent a diagnostic work-up, including MRI and X-rays of the sacroiliac joints (SIJ), to establish diagnosis of axSpA (ASAS criteria). Clinical features, disease activity and functional indices, imaging were collected at baseline and yearly during 48-months. Spinal and SIJ X-rays and MRIs were scored by 2 readers following SPARCC, mSASSS and mNY-criteria. Characteristics of axSpA patients with/without psoriasis were compared over-time with descriptive statistics; multivariate-logistic-regression model was constructed to assess predictors of spinal/pelvic radiographic progression.

RESULTS

88 patients had axSpA (84.1% non-radiographic; 15.9% radiographic); 36.4% had psoriasis. Patients with psoriasis were older; less frequently had HLA-B27+ and radiographic sacroiliitis with unilateral/asymmetric pattern and more signs of spondylitis. Functional and disease activity indices decreased with slightly higher BASDAI and BASFI in axSpA with psoriasis. All patients showed slight spinal/pelvic radiographic progression. Patients without psoriasis showed increased sacroiliitis progression and low-grade spinal progression. More inflammatory corner lesions on cervical/thoracic MRI-spine were observed in patients with psoriasis. Significant downtrend of SPARCC SIJ/spine scores in all patients was found. Psoriasis was a predictor of increased spinal progression (OR = 0.18; 95%CI : 0.04-0.78).

CONCLUSIONS

Psoriasis was associated with distinct axSpA features, increased spinal radiographic progression and low-grade radiographic sacroiliitis.

Managing Psoriatic Arthritis With Inflammatory Bowel Disease and/or Uveitis

Psoriatic arthritis (PsA) is a chronic inflammatory disease that presents with psoriasis (PsO), peripheral and axial arthropathy. The heterogeneity of disease presentation leads to the term "psoriatic disease (PsD)" which is thought to better encompass the range of clinical manifestations. PsA is associated with several comorbidities such as cardiovascular diseases, metabolic syndrome and other extra-articular manifestations including uveitis, and inflammatory bowel disease (IBD). While novel therapeutics are being developed following advances in our understanding of the pathogenesis of the disease, the diverse combinations of PsA with its various comorbidities still pose a clinical challenge in managing patients with PsA. This article reviews our current understanding of the pathogenesis of PsA and how various pathways in the pathogenesis lead to the two comorbid extra-articular manifestations - uveitis and IBD. We also review current evidence of treatment strategies in managing patients with PsA with comorbidities of uveitis and/or IBD.

Differentiating Psoriatic Arthritis from Osteoarthritis and Rheumatoid Arthritis: A Narrative Review and Guide for Advanced Practice Providers

Psoriatic arthritis (PsA) is a chronic inflammatory disease that affects multiple organ systems and is characterized by skin and joint manifestations. PsA is frequently undiagnosed and/or misdiagnosed, especially because of the similarities in clinical presentation shared with other arthritic diseases, including rheumatoid arthritis (RA) and osteoarthritis (OA). An accurate and timely diagnosis of PsA is crucial to prevent delays in optimal treatment, which can lead to irreversible joint damage and increased functional disability. Patients are usually seen by a number of different healthcare providers on their path to a diagnosis of PsA, including advanced practice providers (APPs). This review provides a comprehensive overview of the characteristic features that can be used to facilitate the differentiation of PsA from RA and OA. Detailed information on clinical manifestations, biomarkers, radiologic features, and therapeutic recommendations for PsA included here can be applied in routine clinical settings to provide APPs with the confidence and knowledge to recognize and refer patients more accurately to rheumatologists for management of patients with PsA.

Unraveling the complexities of psoriatic arthritis by the use of -Omics and their relevance for clinical care

-Omic technologies represent a novel approach to unravel ill-defined aspects of psoriatic arthritis (PsA). Large-scale information can be acquired from analysis of affected tissues in PsA via high-throughput studies in the domains of genomics, transcriptomics, epigenetics, proteomics and metabolomics. This is a critical overview of the current knowledge of -omics in PsA, with emphasis on the pathophysiological insights of diagnostic and therapeutic relevance, the advent of novel biomarkers and their potential use for precision medicine in PsA.

Psoriatic arthritis

Psoriatic arthritis (PsA) is a complex inflammatory disease with heterogeneous clinical features, which complicates psoriasis in 30% of patients. There are no diagnostic criteria or tests available. Diagnosis is most commonly made by identifying inflammatory musculoskeletal features in joints, entheses or the spine in the presence of skin and/or nail psoriasis and in the usual absence of rheumatoid factor and anti-cyclic citrullinated peptide. The evolution of psoriasis to PsA may occur in stages, although the mechanisms are unclear. In many patients, there may be little or no relationship between severity of musculoskeletal inflammation and severity of skin or nail psoriasis. The reason for this disease heterogeneity may be explained by differences in genotype, especially in the HLA region. New targeted therapies for PsA have been approved with additional therapies in development. These developments have substantially improved both short-term and long-term outcomes including a reduction in musculoskeletal and skin manifestations and in radiographic damage. With efforts underway aimed at improving our understanding of the molecular basis for the heterogeneity of PsA, a personalized approach to treating PsA may become possible.

IL-23 inhibition for the treatment of psoriatic arthritis

Introduction: Psoriatic arthritis (PsA) is a complex, polygenic immune-mediated disease with varying clinical presentations involving the skin, nails, entheses, and axial/peripheral skeleton.Areas covered: Pathophysiology of PsA with special focus on IL-23/IL-17 axis. Novel classes of targeted therapies for PsA. Pharmacologic properties, efficacy and safety of guselkumab, the only FDA approved agent from IL-23p19 inhibitor class. Data regarding other IL-23 inhibitors (Ustekinumab - an IL-12/IL-23p40 inhibitor, Risankizumab and Tildrakizumab - both IL23p19 inhibitors), in the treatment of PsA.Expert opinion: There are seven classes of FDA-approved therapies for the treatment of PsA. IL-23p19 inhibitors are the newest class of medications that has shown efficacy and reasonable safety profile in the treatment of PsA in phase 2 and phase 3 studies; Guselkumab is the only FDA-approved biologic for PsA within this class . While no head-to-head studies of IL-23p19 inhibitors and other PsA targeted therapies are available, the efficacy of these agents on musculoskeletal system appears to be comparable to TNF-inhibitors (TNFi), and the efficacy on the skin appears to be comparable, or modestly superior to the IL-17 inhibitors (IL-17i). With a superior safety profile compared to TNFi and IL-17i, IL-23p19 inhibitors have the potential to become a first-line biologic in the treatment of PsA.

Clinical and molecular significance of genetic loci associated with psoriatic arthritis

Psoriatic arthritis (PsA) is caused by a combination of environmental and multiple genetic factors, with clear evidence for a strong genetic basis. The remarkable accumulation of knowledge gained from genetic, pharmacogenetic, and therapeutic response of biologic agents in PsA has fundamentally changed and advanced our understanding of disease pathogenesis and has identified key signalling pathways. However, only one-quarter of the genetic contribution of PsA has been accounted for; and dissecting the genetic contributors of the cutaneous disease from those that would identify joint disease has been challenging. More importantly, the clinical utility of multiple proposed loci is unclear. In this review, we summarize the potential clinical relevance from established genetic associations and provide insight on the proposed molecular pathways that arise from these associations.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Recent Updates in the Immunopathology of Type 3 Immunity-Mediated Enthesitis

PURPOSE OF REVIEW

Enthesitis is a cardinal feature of spondyloarthritis (SpA). Despite increasing available treatments, challenges remain in adequately controlling inflammation and subsequent new bone formation (NBF) in entheses; thus, a better understanding of the immunopathogenesis is warranted.

RECENT FINDINGS

Increasing evidence has identified immune cells playing key roles in enthesitis such as γδ T cells and group 3 innate lymphoid cells (ILC3), possibly with site-specific regulatory systems. The presence of T cells producing interleukin (IL)-17 independent of IL-23 in human spinal entheses was recently reported, which may corroborate the discrepancy between recent clinical trials and pre-clinical studies. In addition, the contribution of myeloid cells has also been focused in both human and pre-clinical SpA models. Moreover, not only the IL-23/IL-17 signaling, but other key type 3 immunity mediators, such as IL-22 and granulocyte-macrophage colony-stimulating factor (GM-CSF), have been reported as pivotal cytokines in inflammation and NBF of entheses. Immune cells demonstrating distinct features orchestrate entheses, leading to the complex landscape of enthesitis. However, recent advances in understanding the immunopathogenesis may provide new therapeutic targets and future research directions.

The Molecular Pathophysiology of Psoriatic Arthritis-The Complex Interplay Between Genetic Predisposition, Epigenetics Factors, and the Microbiome

Psoriasis is a symmetric autoimmune/inflammatory disease that primarily affects the skin. In a significant proportion of cases, it is accompanied by arthritis that can affect any joint, the spine, and/or include enthesitis. Psoriasis and psoriatic arthritis are multifactor disorders characterized by aberrant immune responses in genetically susceptible individuals in the presence of additional (environmental) factors, including changes in microbiota and/or epigenetic marks. Epigenetic changes can be heritable or acquired (e.g., through changes in diet/microbiota or as a response to therapeutics) and, together with genetic factors, contribute to disease expression. In psoriasis, epigenetic alterations are mainly related to cell proliferation, cytokine signaling and microbial tolerance. Understanding the complex interplay between heritable and acquired pathomechanistic factors contributing to the development and maintenance of psoriasis is crucial for the identification and validation of diagnostic and predictive biomarkers, and the introduction of individualized effective and tolerable new treatments. This review summarizes the current understanding of immune activation, genetic, and environmental factors that contribute to the pathogenesis of psoriatic arthritis. Particular focus is on the interactions between these factors to propose a multifactorial disease model.

Insights into the pathogenesis of psoriatic arthritis from genetic studies

Psoriatic arthritis (PsA) is a relatively common inflammatory arthritis, a spondyloarthritis (SpA), that occurs most often in patients with psoriasis, a common immune-mediated inflammatory skin disease. Both psoriasis and PsA are highly heritable. Genetic and recent genomic studies have identified variants associated with psoriasis and PsA, but variants differentiating psoriasis from PsA are few. In this review, we describe recent developments in understanding the genetic burden of PsA, linkage, association and epigenetic studies. Using pathway analysis, we provide further insights into the similarities and differences between PsA and psoriasis, as well as between PsA and other immune-mediated inflammatory diseases, particularly ankylosing spondylitis, another SpA. Environmental factors that may trigger PsA in patients with psoriasis are also reviewed. To further understand the pathogenetic differences between PsA and psoriasis as well as other SpA, larger cohort studies of well-phenotyped subjects with integrated analysis of genomic, epigenomic, transcriptomic, proteomic and metabolomic data using interomic system biology approaches are required.

The many faces of psoriatic arthritis: their genetic determinism

In this review, we propose a model of PsA as a complex genetically determined autoimmune-mediated disease having a heterogeneous variety of subphenotypes, with each subphenotype under the control of a different susceptibility-associated HLA allele. Since the specific HLA molecules encoded by each susceptibility allele dominantly select a T cell repertoire with the property of recognizing different peptides, we hypothesize each subphenotype reflects a distinct adaptive autoimmune response directed to different target molecules that is mediated by T cells within each selected repertoire. The interaction among the patients’ susceptibility alleles in the selection of their T cell repertoires determines a spectrum of overall clinical disease severity, varying from mild to severe. We further speculate that these different immune responses may result in activation of different immune effector pathways, which might therefore respond differently to various specific biologic agents.

The IL-17/IL-23 Axis and Its Genetic Contribution to Psoriatic Arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory disease belonging to the family of spondyloarthropathies (SpA). PsA commonly aggravates psoriasis of the skin and frequently manifests as an oligoarthritis with axial skeletal involvement and extraarticular manifestations including dactylitis, enthesitis, and uveitis. The weight of genetic predisposition to psoriasis and PsA is illustrated by the concordance rates in monozygotic twins which clearly demonstrate that genomics is insufficient to induce the clinical phenotype. The association of PsA with several single nucleotide polymorphisms (SNPs) at the IL23R locus and the involvement of Th17 cells in the immunopathogenesis of PsA clearly put the IL-23/IL-17 axis in the spotlight. The IL-23 and IL-17 cytokines have a pivotal role in the chronic inflammation of the synovium in PsA and are also prominent in the skin lesions of those with PsA. In this review, we focus on the genetic association of the IL-23/IL-17 axis with PsA and the contribution of these master cytokines in the pathophysiology of the disease, highlighting the main cell types incriminated in PsA and their specific role in the peripheral blood, lesional skin and joints of patients. We then provide an overview of the approved biologic drugs targeting the IL-23/IL-17 axis and discuss the advantages of genetic stratification to enhance personalized therapies in PsA.

Applying precision medicine to unmet clinical needs in psoriatic disease

Psoriatic disease (PsD) is a heterogeneous condition that can affect peripheral and axial joints (arthritis), entheses, skin (psoriasis) and other structures. Over the past decade, considerable advances have been made both in our understanding of the pathogenesis of PsD and in the treatment of its diverse manifestations. However, several major areas of continued unmet need in the care of patients with PsD have been identified. One of these areas is the prediction of poor outcome, notably radiographic outcome in patients with psoriatic arthritis, so that stratified medicine approaches can be taken; another is predicting response to the numerous current and emerging therapies for PsD, so that precision medicine can be applied to rapidly improve clinical outcome and reduce the risk of toxicity. In order to address these needs, novel approaches, including imaging, tissue analysis and the application of proteogenomic technologies, are proposed as methodological solutions that will assist the dissection of the critical immune-metabolic pathways in this complex disease. Learning from advances made in other inflammatory diseases, it is time to address these unmet needs in a multi-centre partnership aimed at improving short-term and long-term outcomes for patients with PsD.

Evaluating Inflammatory Versus Mechanical Back Pain in Individuals with Psoriatic Arthritis: A Review of the Literature

Psoriatic arthritis (PsA) is a chronic immune-mediated disease characterized by psoriatic skin and nail changes, peripheral joint inflammation, enthesitis, dactylitis, and/or axial involvement, either alone or in combination with each other. The presence of axial involvement has been shown to be a marker of PsA severity; however, there is no widely accepted definition of axial involvement in PsA (axPsA) or consensus on how or when to screen and treat patients with suspected axPsA. Chronic back pain is a prominent feature of axPsA and is thought to have a relevant role in early identification of disease. Chronic back pain can be caused by inflammatory back pain (IBP) or mechanical back pain (MBP). However, MBP can complicate recognition of IBP and delay diagnosis of axPsA. While MBP can also be associated with chronic back pain of ≥ 3 months in duration that is typical of IBP, IBP is characterized by inflammation of the sacroiliac joint and lower spine that is differentiated from MBP by key characteristic features, including insidious onset at age < 40 years, improvement with exercise but not with rest, and nighttime pain. This review discusses the differences in identification and management of IBP and MBP in patients with PsA with axPsA. The summary of available evidence highlights the importance of appropriate and timely screening, difficulties and limitations of differential diagnoses and treatment, and unmet needs in axPsA.

Psoriatic arthritis (PsA) is a long-term disease that may lead to psoriatic changes in skin and nails; inflammation of some joints, including finger and toe joints (dactylitis); inflammation of sites where tendons and ligaments connect to bone (enthesitis); and/or problems in the spine (axial involvement). Approximately 25–70% of patients with PsA have axial involvement (axPsA); this number varies because there is no widely accepted definition for axPsA. Chronic (long-lasting) back pain is a major feature of axSpA and can help doctors recognize axPsA early. Chronic back pain can be caused by inflammatory back pain (IBP) or mechanical back pain (MBP). IBP is described by back pain lasting ≥ 3 months, gradual onset at age < 40 years, improvement with exercise, no improvement with rest, pain at night (with improvement upon getting up), and changes in some laboratory test results. On the other hand, MBP is caused by a physical injury to the lower back. Both IBP and MBP can occur in patients with PsA, but they are treated in different ways. Being able to tell the difference between IBP and MBP is important to make sure that patients receive the right treatment. This review looks at the differences between IBP and MBP, screening for IBP, the difficulties and limitations of diagnosing and treating axPsA, and the needs of patients with axPsA for better diagnosis and treatment.

Not your average joint: Towards precision medicine in psoriatic arthritis

Precision medicine, propelled by advances in multi-omics methods and analytics, aims to revolutionize patient care by using clinically-actionable molecular markers to guide diagnostic and therapeutic decisions. We describe the applications of precision medicine in risk stratification, drug selection, and treatment response prediction in psoriatic arthritis, for which targeted, personalized approaches are steadily emerging.

Elevated CRP even at the first visit to a rheumatologist is associated with long-term poor outcomes in patients with psoriatic arthritis

OBJECTIVES

Little is known about the long-term association of CRP levels during psoriatic arthritis (PsA) disease course. In this study, we examined whether raised CRP over the disease course is associated with worse outcome measures in a well-characterised PsA cohort with a long-term follow up.

METHODS

A cohort of 283 PsA patients (fulfilling CASPAR criteria) was evaluated. All underwent detailed skin and rheumatologic assessments. Moreover, we documented the presence/absence of comorbidities using Charlson Comorbidity Index (CCI). CRP at first visit to a rheumatologist was documented. Cumulative inflammation over time was represented by the cumulative averages of CRP (ca-CRP). Multiple linear regression modelling CRP was used.

RESULTS

Two hundred eighty-three PsA patients attended for detailed assessments. A total of 56.5% (n = 160) of the cohort had raised CRP at their first visit to our rheumatology department, and this was significantly associated with long-term erosions, sacroiliitis, PsA requiring TNFi, and high comorbidity Index, on logistic regression analysis. Moreover, 24% (n = 69) of the cohort never had raised CRP during their long-term follow-up, and on logistic regression analysis, such patients had significantly milder disease with fewer erosions, less sacroiliitis and fewer patients requiring TNFi therapy. The median (IQR) and mean (SD) Ca-CRP was 8.8 (4.6-14.8) and 11.72 (10.52), respectively. On multiple linear regression, erosions, sacroiliitis and CCI were most significantly associated with ca-CRP [(F = 77.6, p < 0.001), 72% (R-square)].

CONCLUSIONS

Elevated CRP is associated with radiographic damage, disease more resistant to treatment and also having higher number of significant comorbidities. Raised CRP can help stratify patients with a more severe PsA phenotype. Key Points • Raised CRP can provide important future prognostic information among patients with PsA. • PsA patients with raised CRP at first visit to a rheumatologist had significantly more destructive and refractory disease. • PsA patients with consistently normal CRP had significantly milder disease.

Complexities in Genetics of Psoriatic Arthritis

PURPOSE OF THE REVIEW

To provide a general overview and current challenges regarding the genetics of psoriatic disease. With the use of integrative medicine, multiple candidate loci identified to date in psoriatic disease will be annotated, summarized, and visualized. Recent studies reporting differences in genetic architecture between psoriatic arthritis and cutaneous-only psoriasis will be highlighted.

RECENT FINDINGS

Focusing on functional pathways that connect previously identified genetic variants can increase our understanding of psoriatic diseases. The genetic architecture differs between psoriatic arthritis and cutaneous-only psoriasis with arthritis-specific signals in linkage disequilibrium independent of the published psoriasis signals. Integrative medicine is helpful in understanding cellular mechanisms of psoriatic diseases. Careful selection of the psoriatic disease cohort has translated into mechanistic differences among psoriatic arthritis and cutaneous psoriasis.

Pathophysiology, assessment and treatment of psoriatic dactylitis

Dactylitis is diffuse swelling of the digits that is usually related to an underlying inflammatory or infiltrative disorder. Psoriatic arthritis (PsA) is the most common severe disease thought to cause dactylitis. Our understanding of the pathogenesis of PsA-related dactylitis comes from experimental animal models of PsA-like disease, as well as advances in imaging and other clinical studies. Clinical trials in PsA have increasingly included dactylitis as an important secondary outcome measure. These studies indicate that cytokines drive multi-locus microanatomical pan-digital pathology. Given the importance of pro-inflammatory cytokines, the pathogenesis of dactylitis is best understood as an initial aberrant innate immune response to biomechanical stress or injury, with subsequent adaptive immune mechanisms amplifying the dactylitis inflammatory response. Regarding the treatment of dactylitis, no studies have been conducted using dactylitis as the primary outcome measure, and the current knowledge comes from analysis of dactylitis as a secondary outcome measure.

The role of epigenetics and immunological imbalance in the etiopathogenesis of psoriasis and psoriatic arthritis

Psoriasis (Ps) and psoriatic arthritis (PsA) represent a clinical and immunopathogenic continuum, called psoriatic disease, cumulatively affecting approximately 3% of the general population. Psoriatic disease is a chronic inflammatory disorder affecting the skin and musculoskeletal system. The immuno-pathogenesis is characterized by an activation of the TNF/IL-23/IL-17 cytokine axis, leading to an immunologic imbalance of T-cells resident in all affected tissues, mainly entheses. In the majority of cases, skin Ps predates rheumatological manifestations. Secondary to the higher incidence and the availability of mouse models, there is stronger data available on skin Ps, and data are, in most cases, relevant also to PsA. In a widely accepted model, environmental trigger factors like infections or trauma are capable of initiating an inflammatory cascade, ultimately creating a sustained state of chronic inflammation in genetically susceptible individuals. Besides well-known genetic susceptibility loci, epigenetic DNA modifications, which are associated with Ps development have been characterized recently and will be discussed in this article. The current evidence is promising in the possibility to provide new therapeutic avenues and fill the unmet need of patients, for whom current treatments either do not allow the disease to be controlled or must be continued for life.

Psoriatic arthritis

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

A case of psoriatic arthritis, with joint involvement preceding skin involvement, successfully treated with adalimumab (80 mg every other week)

Here we present a 45-year-old male patient who suffered from psoriatic arthritis (PsA), for which adalimumab (80 mg every other week) was effective. Dose escalation of a TNF-α antagonist should be considered for patients showing an inadequate response for disease stabilization in PsA.