HLA-C locus alleles may modulate the clinical expression of psoriatic arthritis

Psoriasis, bone and bowel: a comprehensive review and new insights

Psoriasis is a chronic immune-mediated disorder affecting about 2% of the population worldwide which is associated with significant morbidity. The disease usually presents as raised, well-demarcated erythematous plaques with adherent silvery scales. Psoriasis can appear at any age but it has two peaks occurring at 15–20 and 55–60 years of age. It affects males and females equally. Despite the multitude of investigations about psoriasis and even development of drugs with satisfactory results, its pathogenesis is not fully understood yet and its course is unpredictable. Various environmental triggers, e.g., obesity, stress and drugs may induce disease in genetically susceptible patients. Although psoriasis was considered primarily as a disease of the skin, more investigations have been revealed its systemic nature. Psoriatic arthritis (PsA) may complicate up to one-third of cases of psoriasis vulgaris (PV). Also, the association between psoriasis and a variety of other immune-mediated disorders such as inflammatory bowel disease (IBD) and celiac disease (CD) has been confirmed in various studies. Moreover, a growing body of evidences indicates that psoriasis shares some common histological and phenotypical properties with the spectrum of osteoimmunological diseases such as Paget’s disease of bone (PDB). Thus, exploring the common molecular and genetic mechanisms underlying psoriasis and related disorders is of paramount importance for better elucidating disease pathogenesis and designing more targeted treatments.

Neuroimmune Mechanisms Underlying Post-acute Sequelae of SARS-CoV-2 (PASC) Pain, Predictions from a Ligand-Receptor Interactome

PURPOSE OF REVIEW

Individuals with post-acute sequelae of SARS-CoV-2 (PASC) complain of persistent musculoskeletal pain. Determining how COVID-19 infection produces persistent pain would be valuable for the development of therapeutics aimed at alleviating these symptoms.

RECENT FINDINGS

To generate hypotheses regarding neuroimmune interactions in PASC, we used a ligand-receptor interactome to make predictions about how ligands from PBMCs in individuals with COVID-19 communicate with dorsal root ganglia (DRG) neurons to induce persistent pain. In a structured literature review of -omics COVID-19 studies, we identified ligands capable of binding to receptors on DRG neurons, which stimulate signaling pathways including immune cell activation and chemotaxis, the complement system, and type I interferon signaling. The most consistent finding across immune cell types was an upregulation of genes encoding the alarmins S100A8/9 and MHC-I. This ligand-receptor interactome, from our hypothesis-generating literature review, can be used to guide future research surrounding mechanisms of PASC-induced pain.

The Conundrum of Psoriatic Arthritis: a Pathogenetic and Clinical Pattern at the Midpoint of Autoinflammation and Autoimmunity

Psoriatic arthritis (PsA) is a chronic inflammatory condition characterized by psoriasis, synovitis, enthesitis, spondylitis, and the possible association with other extra-articular manifestations and comorbidities. It is a multifaceted and systemic disorder sustained by complex pathogenesis, combining aspects of autoinflammation and autoimmunity. Features of PsA autoinflammation include the role of biomechanical stress in the onset and/or exacerbation of the disease; the evidence of involvement of the innate immune response mediators in the skin, peripheral blood and synovial tissue; an equal gender distribution; the clinical course which may encounter periods of prolonged remission and overlapping features with autoinflammatory syndromes. Conversely, the role of autoimmunity is evoked by the association with class I major histocompatibility complex alleles, the polyarticular pattern of the disease which sometimes resembles rheumatoid arthritis and the presence of serum autoantibodies. Genetics also provide important insights into the pathogenesis of PsA, particularly related to class I HLA being associated with psoriasis and PsA. In this review, we provide a comprehensive review of the pathogenesis, genetics and clinical features of PsA that endorse the mixed nature of a disorder at the crossroads of autoinflammation and autoimmunity.

HLA-C Genotyping Reveals Haplotype C*07 as a Potential Biomarker of Late Psoriasis Onset in Moroccan Patients

Psoriasis still has an unknown etiology. Genetic predisposition shows the association between HLA-Cw6 allele and psoriasis. Although biotherapies have been proven effective in psoriasis treatment, methotrexate (MTX) is still used as a first-line systemic therapy due to its efficacy/affordability, but the differential response to MTX is mostly related to interindividual genetic variability and remains an issue. Our study aimed to analyze HLA-C allele frequencies in a sample of Moroccan psoriatic patients and assess the therapeutic response to MTX. Whole blood of 54 Moroccan psoriatic patients was collected and DNA was extracted. Patients' HLA-C locus was genotyped by PCR-SSO. Results were analyzed with Luminex xMAP Technology and Match-it DNA Evolution 3.4. HLA-C typing results of 77 sex- and age-matched unrelated non-psoriatic healthy subjects were included. We observed no difference in the allelic distribution of HLA-C between patients and healthy controls, suggesting that none of the HLA-C alleles were significantly associated with psoriasis. Moreover, the HLA-C*07 allele was associated with a late age at disease onset (>30 years old) (p = 0.007). No statistically significant association was found between HLA-C allele expression and response to MTX, despite a higher frequency of HLA-C*06 in responders compared to non-responders. Thus, HLA-C*07 could be a biomarker of late psoriasis onset in the Moroccan population.

Axial involvement in psoriatic arthritis

Among the variety of clinical manifestations of psoriatic arthritis (PsA) – including peripheral arthritis, dactylitis, enthesitis, and axial disease – spondylitis is the least studied. There is no generally accepted definition of axial PsA (axPsA), nor is there any common terminology or diagnostic criteria for it. In the rheumatology community, there is also no consensus regarding radiological and MRI assessment of axial involvement in PsA patients, while disease activity indexes and the therapeutic tactics are borrowed from those used in treating axial spondyloarthritis (axSpA) and ankylosing spondylitis (AS). However, despite a range of similarities in immunopathogenetic mechanisms of axPsA and axSpA, there are also certain differences that may affect the treatment response in these patients. The aim of this review is the analysis of data on axial disease in PsA. The article discusses the genetic features, clinical presentations, imaging techniques, differential diagnostics and treatment options of axPsA.

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.

Isolated axial disease in psoriatic arthritis and ankylosing spondylitis with psoriasis

OBJECTIVES

To compare isolated axial psoriatic arthritis (PsA), axial PsA with peripheral involvement and isolated axial ankylosing spondylitis (AS) with psoriasis. To evaluate predictors for developing peripheral disease from isolated axial PsA over time.

METHODS

Two PsA and AS cohorts identified patients with PsA with axial disease and isolated axial patients with AS with psoriasis. Logistic regression compared isolated axial PsA to axial PsA with peripheral involvement and isolated axial AS with psoriasis. Cox proportional hazards model evaluated predictors for developing peripheral disease from isolated axial PsA.

RESULTS

Of 1576 patients with PsA, 2.03% had isolated axial disease and 29.38% had axial and peripheral disease. human leucocyte antigen HLA-B*27 positivity (OR 25.00, 95% CI 3.03 to 206.11) and lower Health Assessment Questionnaire scores (OR 0.004, 95% CI 0.00 to 0.28) were associated with isolated axial disease. HLA-B*27 also predicted peripheral disease development over time (HR 7.54, 95% CI 1.79 to 31.77). Of 1688 patients with AS, 4.86% had isolated axial disease with psoriasis. Isolated axial patients with PsA were older at diagnosis (OR 1.06, 95% CI 1.01 to 1.13), more likely to have nail lesions (OR 12.37, 95% CI 2.22 to 69.07) and less likely to have inflammatory back pain (OR 0.12, 95% CI 0.02 to 0.61) compared with patients with isolated axial AS with psoriasis.

CONCLUSIONS

Isolated axial PsA and AS with psoriasis are uncommon. HLA-B*27 positivity is associated with isolated axial PsA and may identify those who develop peripheral disease over time. Isolated axial PsA is associated with better functional status. Isolated axial PsA appears clinically distinct from isolated axial AS with psoriasis.

Psoriatic arthritis

Psoriatic arthritis (PsA) is a type of inflammatory arthritis that is included within the spondyloarthritis, a group of rheumatological diseases characterized by different clinical manifestations and associated comorbidities, that can compromise the quality of life of patients. The diagnosis of PsA is sometimes difficult due to an enormous clinical and radiological variability, including six different domains of involvement: peripheral joint, axial skeleton, skin psoriasis, nail psoriasis, enthesitis and dactylitis. Currently, there are no biomarkers that allow the detection of PsA in patients with psoriasis, so a high level of suspicion is important, mainly by dermatologists, but also by other specialists, such as family doctors. Advances in the knowledge of new immunological mechanisms and joint management by rheumatologists and dermatologists have made it possible to improve the therapeutic approach in patients with PsA.

Potential Differences in the Cardiometabolic Risk Profile of Patients with Psoriatic Disease according to Their HLA-C ∗ 06 Status

The human leukocyte antigen-C∗06 (HLA-C∗06, formerly HLA-Cw6) is the main genetic biomarker in psoriatic disease. It has been related to several phenotypic traits in psoriatic disease, but its role in relation to cardiometabolic comorbidities is unknown at present. Here, we analyze the potential connections between this biomarker and the cardiometabolic profile of these patients. We carried out a cross-sectional observational study including 400 patients recruited at a single university hospital. Clinical and classical cardiometabolic factors were compared between HLA-C∗06-positive and HLA-C∗06-negative individuals (OR with 95% CI). Multivariate regression analyses were carried out to check for disease traits associated with different cardiometabolic risk factors. The study population included 215 men (53.8%) and 185 women (46.2%), mean age of 46 ± 15 years, and an average disease evolution of 17 ± 12.6 years. Ninety-three (23.3%) patients met CASPAR criteria for psoriatic arthritis. HLA-C∗06 carriers (n: 160, 40%) showed an earlier age at disease onset, psoriasis family history, and more severe skin disease (type I disease). After correcting for age, sex, and disease duration, they also showed less hypertension (13.8% vs. 24.2%, OR 0.7 (95% CI: 0.42-0.78), p = 0.025), lower waist circumference (94.4 ± 13.7 vs. 98.3 ± 13.8 cm), and lower BMI (27 ± 4.4 vs. 28.1 ± 4.8, p < 0.05). We confirmed the well-known association between HLA-C∗06 and type I psoriatic disease. As a novel finding, patients carrying HLA-C∗06 showed a better cardiometabolic profile. In any case, these findings need further confirmation.

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.

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.

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.

Genetics, Epigenetics, and Gender Impact in Axial-Spondyloarthritis Susceptibility: An Update on Genetic Polymorphisms and Their Sex Related Associations

Spondyloarthritis (SpA) is a group of chronic inflammatory rheumatic disease that can be divided into predominantly axial or predominantly peripheral involvement, with or without associated psoriasis, inflammatory bowel disease or previous infection. Axial SpA (axSpA) encompasses ankylosing spondylitis (AS) with radiological sacroiliitis, and a type without radiographic sacroiliitis, called “non-radiographic axial SpA” (nr-axSpA). Males and females show large differences in their susceptibility to SpA, such as distinctions in clinical patterns, phenotypes and in therapeutical response, particularly to TNF inhibitors (TNFi). Several studies indicate that AS women have doubled risk to failure TNFi compared with males. This diversity in drugs’ efficacy among women and men may be caused by differences in the balance of sex hormones and in gene-specific expression likely triggered by X-chromosome instability and gene-specific epigenetic modifications. Evidence reported that polymorphisms in microRNAs on X- and other chromosomes, such as miR-146a, miR-155, miR-125a-5p, miR-151a-3p and miR-22-3p, miR-199a-5p could be involved in the different clinical presentation of SpA, as well as disease activity. In addition, association with non−response to TNFi treatment and presence of IRAK3 and CHUCK genes in SpA patients was recently detected. Finally, polymorphisms in genes involved in IL-23/IL-17 pathway, such as in drug pharmacodynamics and pharmacokinetics may have a role in response to TNFi, IL17i, and IL23i. A major understanding of genomic variability could help in the development of new therapeutic targets or in taking advantages of different mechanisms of action of biological drugs. Moving from the multifactorial etiology of disease, the present review aims at evaluating genetic and epigenetic factors and their relationship with sex and bDMARDs response, helping to investigate the different expression among males and females of genes on X- and other chromosomes, as well as mi-RNA, to highlight relationships between sex and occurrence of specific phenotypes and symptoms of the disease. Moreover, the role of the epigenetic modification in relation to immune-regulatory mechanisms will be evaluated.

The association of HLA-C and ERAP1 polymorphisms in early and late onset psoriasis and psoriatic arthritis patients of Hungary

Introduction

Single nucleotide polymorphisms (SNPs) of the HLA-C and ERAP1 genes were recently determined to contribute to psoriasis susceptibility. However, data regarding the association of these genes with specific subgroups of psoriasis are scarce.

Aim

To examine the possible association of the HLA-C and ERAP-1 polymorphisms with early and late onset psoriasis and psoriatic arthritis.

Material and methods

Five ERAP1 SNPs and two HLA-C SNPs were genotyped in 105 psoriatic arthritis patients, 214 cutaneous psoriasis patients and 200 healthy individuals. Haplotypes were constructed for three ERAP1 SNPs (rs17482078, rs10050860, rs30187), and interaction between HLA-Cw*0602 and ERAP1 was also analysed.

Results

The HLA-Cw*0602 rs10484554 SNP was found to be a strong susceptibility factor for early onset cutaneous psoriasis and early onset psoriatic arthritis. ERAP1 SNPs (rs10050860, rs17482078, rs27525) appear to have a protective function for early onset psoriatic arthritis. The haplotype B was identified as a susceptibility factor for late onset psoriatic arthritis. In HLA-C positive individuals the rs27524 ERAP1 SNP was associated with a significantly increased risk of psoriatic arthritis development, whereas the rs27525 ERAP1 SNP had the opposite effect.

Conclusions

These results suggest that the HLA-C and ERAP1 genes contribute to the pathogenesis of psoriasis and psoriatic arthritis in an age-dependent manner.

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.

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.

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.

Associations between human leukocyte antigen C locus polymorphism and psoriatic arthritis in populations of European and Middle Eastern descent: a meta-analysis

BACKGROUND

Gene-disease association between human leukocyte antigen (HLA)-C locus polymorphism and psoriatic arthritis (PsA) remains controversial.

OBJECTIVE

Evaluate the relationship between HLA-C locus polymorphism and PsA in populations of European and Middle Eastern descent.

SEARCH METHODS

PubMed, PMC, Elsevier and Google Scholar databases from 1980 to January 2020. The search was limited to articles in English.

SELECTION CRITERIA

Case-control studies (with unrelated participants) that had allele/genotype data on the association between HLA-C locus polymorphism and PsA susceptibility.

DATA COLLECTION AND ANALYSIS

Two investigators searched independently in searching the literature. Disagreements were resolved by discussion and consultation with a third researcher. The Q-Genie tool was used to assess the quality of articles.

RESULTS

Twenty-five studies met the inclusion criteria. At the allelic level, three alleles were associated with an increased risk of PsA and five were associated with a reduced risk. At the phenotypic level, four alleles were associated with increased risk of PsA and three were associated with a reduced risk. At both the allelic and phenotypic levels, the results revealed that HLA-C*04 played a protective role in PsA (The pooled odds ratio [OR] is 0.66 for allelic level and 0.63 for phenotypic level), while HLA-C*02, *06 and *12 increased the risk of suffering from PsA (The pooled ORs of C*02, *06 and *12 are 2.21, 2.63 and 1.49 for allelic level, and 1.79, 2.96 and 2.25 for phenotypic level, respectively).

CONCLUSION

The pooled results showed a significant association between PsA and the HLA-C gene in populations of European and Middle Eastern descent. At both the allelic and phenotypic levels, the HLA-C*02, *06 and *12 may contribute to susceptibility to PsA, while HLA-C*04 may confer a protective role against PsA.

REGISTRATION

Not registered.

CONFLICT OF INTEREST

None.

Axial Psoriatic Arthritis: A Distinct Clinical Entity in Search of a Definition

Axial involvement in psoriatic arthritis is a well-recognized manifestation with a prevalence between 12.5% and 78%. This huge heterogeneity is due to the different criteria used by authors to define psoriatic arthritis with axial involvement combining clinical features with radiographic evidence of disease. Specific genetic and clinical attributes of axial psoriatic arthritis might differentiate it from axial spondyloarthritis with concurrent skin psoriasis. Few studies address the specific management. The purpose of this review is to acknowledge the current understanding of axial involvement in psoriatic arthritis and highlight the need for a definition to facilitate research and clinical recognition.

Axial disease in psoriatic arthritis and ankylosing spondylitis: a critical comparison

Ankylosing spondylitis (AS) was first identified in the late 17th century. 250 years later, inflammatory spine disease was recognized to be one of the patterns of psoriatic arthritis (PsA). Isolated spondylitis is rare among patients with PsA, occurring in less than 5% of patients; however, many patients with PsA have axial disease that is concurrent with peripheral arthritis. At the other end of the spondyloarthritis spectrum, psoriasis is observed in 10% of patients with AS. Although axial involvement in PsA can be indistinguishable from axial disease in AS, it can also differ in several respects, raising the question of whether axial PsA and AS (with or without psoriasis) are different clinical presentations of the same disease, or whether they are separate diseases that have overlapping features. In this Review, the clinical presentation, metrology, radiographic characteristics, genetic factors, treatment options and axial prognosis of the two diseases are addressed. The aim of this Review is to capture all available comparisons made to date, to highlight the similarities and differences between AS and axial PsA and to propose a research agenda.

Human leukocyte antigen and demographic characteristics in Chinese patients with active peripheral type psoriatic arthritis who had inadequate response to conventional disease-modifying antirheumatic drugs in a single dermatologic clinic

Background

Correlation between severity of psoriasis and psoriatic arthritis (PsA) is inconsistent. Also, human leukocyte antigen (HLA)-Cw6 was found to be underrepresented in severe psoriasis who failed conventional systemic therapies, but the effect of HLA polymorphism on PsA severity needs to be confirmed.

Objectives

To describe the severity of psoriasis, demographic features and HLA polymorphism among Chinese patients with active peripheral type PsA who had inadequate response to conventional disease-modifying antirheumatic drugs.

Methods

We included all patients with PsA who had at least 3 tender and swollen peripheral joints despite at least two conventional non-biologic treatments in our clinic. Demographic results were compared with global pivotal studies of biologics for PsA. HLA-Cw and HLA-DRB1 genotyping was also analyzed.

Results

We identified 60 patients who met our inclusion criteria. The male to female ratio was 1.31:1. The majority of patients presented with psoriasis first (81.7%). The mean interval between psoriasis and PsA was 7.2 ± 8.1 years (mean ± SD). The baseline number of tender and swollen joints was 14.9 ± 10.7 and 11.3 ±10.2, respectively. In total, 41.7% subjects had more than 3% body surface area involvement of psoriasis. Genotyping of HLA-Cw and HLA-DRB1 was performed in 47 subjects. HLA-Cw*0702 was the most frequent allele (29.8%), followed by HLA-Cw*01 (26.6%). The frequency of HLA-Cw*0602 allele was similar to normal population. The most frequent HLA-DRB1 allele was HLA-DRB1*04 (20.2%), followed by HLA-DRB1*08 (16.0%). No cases carrying HLA-DRB1*13 were detected.

Conclusions

Compared with Western population, our patients had less psoriasis and PsA burden. The frequencies of HLA-Cw*06, HLA-Cw*12, and HLA-DRB1*07 were not increased. In contrast, HLA-Cw*0702 and HLA-DRB1*08 allele frequencies were increased compared with psoriasis patients and normal population in Taiwan. Future studies are still needed to characterize the demographic and genetic features of high need PsA patients.

Investigation of Psoriasis Susceptibility Loci in Psoriatic Arthritis and a Generalized Pustular Psoriasis Cohort

Psoriasis is a common skin disease affecting 1-3% of the population (Gelfand et al., 2005; Ferrándiz et al., 2001). Approximately 30% of patients with psoriasis develop psoriatic arthritis (PsA), an inflammatory arthritis associated with psoriasis (Haroon et al., 2013; Prey et al., 2010). Generalized pustular psoriasis (GPP) affects about 1.3% of psoriasis patients. Recently, numerous novel susceptibility loci for psoriasis vulgaris (PsV) have been discovered thorough the application of genome-wide association studies (GWASs). Among them, the major histocompability complex is the locus with the strongest effect. Outside the major histocompability complex region, the novel susceptibility loci of PsV can be incorporated into an integrated pathogenic model comprising distinct signaling networks affecting skin barrier function, innate immune responses involving NF-κB signaling, and adaptive immune responses involving CD8 T cells and IL-23/IL-17-mediated lymphocyte signaling. Compared with PsV, only three GWASs were performed in PsA (Ellinghaus et al., 2012; Hüffmeier et al., 2010; Stuart et al., 2015), accompanied with other candidate gene studies, most of the PsA susceptibility loci have been proved to be associated with PsV. However, the genetic study of GPP is quite different. Up to now, IL36RN is the only associated gene of GPP that has been widely verified. The data are based on homozygosity mapping and direct sequencing in consanguineous Tunisian multiplex families with autosomal recessive GPP (Marrakchi et al., 2011). Some researchers suggested that GPP and PsV are etiologically distinct clinical entities (Capon, 2013), challenging the traditional understanding of psoriasis. The percentages of IL36RN-negative patients have been reported to range from 51% (Li et al., 2013) to 84% (Setta-Kaffetzi et al., 2013), implying that additional risk loci, genetic interactions, and other factors may account for the other GPP cases. Recently, more than 10 GWASs of PsV have identified a number of susceptibility loci, making PsV GWASs a rich source of potential risk loci for other subtypes of psoriasis. Here, we use information emerging form PsV GWASs to make inferences about the genetic etiology of PsA and GPP in a Chinese population.

Late onset psoriatic arthritis in a longitudinal cohort: Disease presentation, activity over time and prognosis

AIMS

To evaluate disease activity of late onset psoriatic arthritis (LoPsA) patients at presentation, during follow-up, and after 5years of follow-up, compared to young onset PsA patients (YoPsA).

METHODS

The study included patients with PsA followed prospectively within 2years from diagnosis. Patients were divided into two groups: (1) LoPsA - defined as disease onset ≥ 50 years, (2) YoPsA - defined as disease onset < 50 years. Descriptive statistics are provided and multivariable logistic regression models were developed to compare these groups.

RESULTS

Five hundred and sixty-six patients were included at presentation. Regression analysis showed that the LoPsA group at presentation was characterized by: less males (OR 0.4, p = 0.001), less HLA-C*06 (OR 0.3, p = 0.005), longer psoriasis duration (OR 1.04, p = 0.0005), higher BMI (OR 1.1, p = 0.005) and higher modified Steinbrocker score (mSS) (OR 1.1, p = 0.005). Regression analysis adjusted for gender, BMI, psoriasis duration, HLA and treatments after 5years of follow-up revealed a trend toward higher adjusted mean active joint count (OR 7.98, p = 0.052) and higher mean mSS score (OR 13.39, p = 0.007) in the LoSpA group compared to the YoPsA group. During 5years of follow-up, the YoPsA patients were treated with more NSAIDs (96% vs. 88%, p = 0.04), while there were no significant differences in the DMARDs and biologic drugs.

CONCLUSION

The LoPsA patients at presentation are characterized by female predominance, higher BMI, more damage and less HLA-C*06. After 5years of follow-up the LoPsA patients have worse prognosis manifested by a trend toward higher disease activity burden and significantly more damage.

HLA-Cw6 and psoriasis

Psoriasis is a multifactorial disease with a strong genetic background. HLA-Cw6 is one of the most strongly associated psoriasis susceptibility alleles. It is repeatedly observed to affect disease course, phenotypic features, severity, comorbidities and treatment outcomes. To the best of our knowledge, the roles of HLA-Cw6 in psoriasis have not yet been thoroughly reviewed. The worldwide frequency of the HLA-Cw6 allele varies greatly, with it being generally higher in white people than in Asians. The allele is associated with type I early-onset psoriasis. Stress, obesity and streptococcal pharyngitis are commonly observed in HLA-Cw6-positive patients. Phenotypically, HLA-Cw6 has been found to be associated with guttate psoriasis. In addition, patients carrying the allele are more likely to have arm, leg and trunk involvement, and the Koebner phenomenon. Patients with psoriatic arthritis with HLA-Cw6 more often have early onset and tend to show cutaneous symptoms before musculoskeletal symptoms. HLA-Cw6-positive patients have been shown in several studies to be more responsive to methotrexate and ustekinumab. However, this difference in ustekinumab efficacy was only moderate in a post-hoc analysis of a pivotal phase III study. HLA-Cw6 positivity also tends to be less frequent in high-need patients who fail conventional therapy. Small studies have also investigated the role of HLA-Cw6 in remission of psoriasis during pregnancy, and with the comorbidities of photosensitivity and atherosclerosis. Given the diverse nature of psoriasis pathogenesis, as well as the difference of HLA-Cw6 positivity in different ethnic groups, more studies are needed to confirm the role of HLA-Cw6 in psoriasis.

Genome-wide Association Analysis of Psoriatic Arthritis and Cutaneous Psoriasis Reveals Differences in Their Genetic Architecture

Psoriasis vulgaris (PsV) is a common inflammatory and hyperproliferative skin disease. Up to 30% of people with PsV eventually develop psoriatic arthritis (PsA), an inflammatory musculoskeletal condition. To discern differences in genetic risk factors for PsA and cutaneous-only psoriasis (PsC), we carried out a genome-wide association study (GWAS) of 1,430 PsA case subjects and 1,417 unaffected control subjects. Meta-analysis of this study with three other GWASs and two targeted genotyping studies, encompassing a total of 9,293 PsV case subjects, 3,061 PsA case subjects, 3,110 PsC case subjects, and 13,670 unaffected control subjects of European descent, detected 10 regions associated with PsA and 11 with PsC at genome-wide (GW) significance. Several of these association signals (IFNLR1, IFIH1, NFKBIA for PsA; TNFRSF9, LCE3C/B, TRAF3IP2, IL23A, NFKBIA for PsC) have not previously achieved GW significance. After replication, we also identified a PsV-associated SNP near CDKAL1 (rs4712528, odds ratio [OR] = 1.16, p = 8.4 × 10(-11)). Among identified psoriasis risk variants, three were more strongly associated with PsC than PsA (rs12189871 near HLA-C, p = 5.0 × 10(-19); rs4908742 near TNFRSF9, p = 0.00020; rs10888503 near LCE3A, p = 0.0014), and two were more strongly associated with PsA than PsC (rs12044149 near IL23R, p = 0.00018; rs9321623 near TNFAIP3, p = 0.00022). The PsA-specific variants were independent of previously identified psoriasis variants near IL23R and TNFAIP3. We also found multiple independent susceptibility variants in the IL12B, NOS2, and IFIH1 regions. These results provide insights into the pathogenetic similarities and differences between PsC and PsA.

HLA-B27 and psoriatic disease: a modern view of an old relationship

Psoriasis and PsA are the main phenotypes of psoriatic disease. Both conditions are highly polygenic diseases in which stochastic and environmental factors are crucial in the pathogenic process. Although the MHC region is a highly dense genetic area, most of the genetic basis of psoriatic disease within it resides in the HLA region. For decades, HLA-C*06 has been accepted as the main descriptor of the two main phenotypes of skin psoriasis. There is now compelling evidence to suggest that HLA-C*06 is only a genetic biomarker for skin involvement and not for joint involvement in psoriatic disease. The role of HLA-B*27 in the genetic aetiology of PsA has been recognized since the 1970s. Recent population case-control studies with adequate patient groups and replication cohorts, as well as confirmation studies in family pedigrees through the use of modern molecular typing methods, have reinforced the aetiological role of this allele in PsA. These studies have offered a new vision of the role of this allele in disease expression. This review contextualizes the latest findings on the role of HLA-B27 in psoriatic disease, emphasizing those aspects of particular interest for clinical practice.

Clinical and immunogenetic characterization in psoriatic arthritis patients

In psoriatic arthritis (PsA), genetic factors play a substantial role in disease susceptibility as well as in its expression. This study aims to determine the distribution of class I and class II HLA antigens in PsA patients and secondly to analyze the influence of genetic factors in the clinical expression of the disease. Consecutive PsA patients (CASPAR criteria) with less than 1 year of disease duration were included. Sociodemographic and clinical data were recorded. Blood samples were obtained, DNA was extracted by polymerase chain reaction (PCR), and class I (A, B, and C) and class II (DR) HLA antigens were determined by oligotyping. A control group of 100 nonrelated healthy controls from the general population served as control. p values were corrected (pc) according to the number of alleles tested. A total of 73 patients were included, 37 were females (50.7 %) with a median disease duration of 72 months (interquartile range (IQR) 24-149). Thirty-three patients (45.2 %) had a family history of psoriasis. When analyzing all the class I and class II HLA antigens, a significantly higher frequency of B38 (odds ratio (OR) 2.95, p = 0.03) and Cw6 (OR 2.78, p = 0.009) was found in PsA patients compared to the control group. On the contrary, the HLA-A11 (OR 0.14, p = 0.04) and B7 (OR 0.31, p = 0.03) were significantly more frequent among healthy controls. Furthermore, B18 was significantly more frequent in patients with early arthritis onset (less than 40 years): seven patients (22.6 %) with early onset compared to two patients (4.8 %) with late onset (p = 0.03). No association between HLA-B27 and spondylitis or HLA-DR4 with polyarticular involvement was observed. The HLA-B38 and Cw6 alleles are associated with a greater PsA susceptibility in Argentine population.

Associations of HLA-A, HLA-B and HLA-C alleles frequency with prevalence of herpes simplex virus infections and diseases across global populations: implication for the development of an universal CD8+ T-cell epitope-based vaccine

A significant portion of the world's population is infected with herpes simplex virus type 1 and/or type 2 (HSV-1 and/or HSV-2), that cause a wide range of diseases including genital herpes, oro-facial herpes, and the potentially blinding ocular herpes. While the global prevalence and distribution of HSV-1 and HSV-2 infections cannot be exactly established, the general trends indicate that: (i) HSV-1 infections are much more prevalent globally than HSV-2; (ii) over a half billion people worldwide are infected with HSV-2; (iii) the sub-Saharan African populations account for a disproportionate burden of genital herpes infections and diseases; (iv) the dramatic differences in the prevalence of herpes infections between regions of the world appear to be associated with differences in the frequencies of human leukocyte antigen (HLA) alleles. The present report: (i) analyzes the prevalence of HSV-1 and HSV-2 infections across various regions of the world; (ii) analyzes potential associations of common HLA-A, HLA-B and HLA-C alleles with the prevalence of HSV-1 and HSV-2 infections in the Caucasoid, Oriental, Hispanic and Black major populations; and (iii) discusses how our recently developed HLA-A, HLA-B, and HLA-C transgenic/H-2 class I null mice will help validate HLA/herpes prevalence associations. Overall, high prevalence of herpes infection and disease appears to be associated with high frequency of HLA-A(∗)24, HLA-B(∗)27, HLA-B(∗)53 and HLA-B(∗)58 alleles. In contrast, low prevalence of herpes infection and disease appears to be associated with high frequency of HLA-B(∗)44 allele. The finding will aid in developing a T-cell epitope-based universal herpes vaccine and immunotherapy.

Age at disease onset: a key factor for understanding psoriatic disease

Psoriasis and PsA are immune-mediated diseases with a strong genetic component. More than 20 new loci have been recently linked to these diseases. However, interactions between these genes and the phenotypic traits of both diseases are poorly understood at present. Stratification of psoriatic disease according to the sex of the patients, genetic factors or age at onset has allowed in the last few years a better understanding of the principles governing the onset and progression of these processes. The age of onset of psoriasis has been used for decades as an appropriate descriptor to define two subpopulations of psoriatic patients (types I and II) whose clinical and immunogenetic characteristics have been very well differentiated. Moreover, in patients with PsA this distinction between type I and II psoriasis also seems equally operative. In patients with PsA expressing the HLA-C*06 antigen, the latency between the onset of psoriasis and onset of joint symptoms is longer than in those without this marker. It is also known that PsA tends to appear earlier in patients with HLA-B*27 positivity, and that these patients also show a shorter interval of time between the onset of cutaneous lesions and the onset of joint disease. This review highlights the growing importance of age at disease onset as a key stratification factor in worldwide clinical and genetic studies of psoriatic disease.

The HLA-Cw*06 allele and -1149 G/T polymorphism of extrapituitary promoter of PRL gene as a possible common genetic predisposing factors to psoriasis vulgaris and psoriatic arthritis in Czech population

Psoriatic arthritis (PsA) affects approximately 30 % of patients suffering from psoriasis vulgaris (PsV), but the risk factors for its development have not been well elucidated yet. The HLA-Cw*06 allele was described as a predisposing factor to PsV. Prolactin is known as an immune response modulator, and its elevated levels present risk for PsV development. It is possible that these factors interact and together emphasize the predisposition to both diseases. We tested on an association of HLA-Cw alleles and functional polymorphism -1149 G/T in PRL gene extrapituitary promoter with PsV and PsA in Czech population. We found a statistically significant association between HLA-Cw*06 allele and PsV (P corrected = 0.0013) that was most prominent in early onset disease subtype (P corrected = 0.0013). The association between HLA-Cw*06 and PsA was low (P corrected = 0.0585) and restricted to PsA patients with early PsV onset (P corrected = 0.0195). We found no association of -1149 G/T PRL gene polymorphism with either PsV or PsA.

HLA associations reveal genetic heterogeneity in psoriatic arthritis and in the psoriasis phenotype

OBJECTIVE

Rigorously ascertained cases of psoriatic arthritis in subjects presenting to a rheumatology unit were compared with cases of psoriasis in subjects presenting to a dermatology unit, where subjects with musculoskeletal features were excluded, to address 1) the extent to which the contribution of the major histocompatibility complex (MHC) to psoriatic arthritis susceptibility resembles that in psoriasis, and 2) whether MHC genes determine quantitative traits within the psoriatic arthritis phenotype.

METHODS

Separate discovery and validation subcohorts of patients recruited from a relatively homogeneous population were studied by sequence-based HLA typing, in which frequencies of the HLA-B and HLA-C alleles and haplotypes were compared.

RESULTS

In patients with psoriatic arthritis, the frequency of C*06:02 was lower than that in patients with psoriasis (28.7% versus 57.5%; P = 9.9 × 10(-12) ). Three haplotypes containing B*27:05 or B*39:01 were significantly increased in frequency in patients with psoriatic arthritis, but not in those with psoriasis. The structurally related B*39:06 allele was not increased in frequency. B*27 was associated with an interval of 0.98 years between skin and musculoskeletal disease (P = 2.05 × 10(-6) ), compared with an interval of 10.14 years for C*06. Preliminary evidence suggested that B*38:01 and B*08 may be associated with psoriatic arthritis susceptibility, and that allotypes encoding P2 pockets that bind side chains opposite in charge from those encoded by the B*27 and B*39 molecules may exert a protective role.

CONCLUSION

These findings suggest that the psoriasis phenotype results from two patterns of MHC effect. The first involves the classic psoriasis susceptibility gene C*06, which confers more penetrant skin disease with less prevalent and more time-dependent musculoskeletal phenotype development. The second pattern appears to be mediated by HLA-B alleles, notably B*27, and includes temporally more coincident musculoskeletal involvement that is nearly equivalent in penetrance to that of the skin disease.

[Biologic therapies different from the anti-TNFα therapy in psoriasis and psoriatic arthritis]

Psoriasis and psoriatic arthritis (PsA) are common conditions in the clinical practice of both dermatologists and rheumatologists. Both entities may cause an important loss in quality of life, and in the case of PsA, joint structural damage may arise over time. For these reasons, clinicians may be faced with the need for treating these cases with highly effective therapies, such as TNFα blocking agents, although these drugs may be paradoxically related with de novo onset (or exacerbation of previous lesions) of psoriasis or psoriasiform lesions. In spite of the clinical efficacy of these therapies, recent registry studies show that up to 25% of PsA cases exposed to anti-TNF therapies are withdrawn from these drugs within the first year of therapy. Therefore, there is a need for the use of alternative biologic therapies in this context. The present review deals with this subject.