Genetic epidemiology of psoriasis and psoriatic arthritis

Functional Genomics in Psoriasis

Psoriasis is an autoimmune cutaneous condition that significantly impacts quality of life and represents a burden on society due to its prevalence. Genome-wide association studies (GWASs) have pinpointed several psoriasis-related risk loci, underlining the disease's complexity. Functional genomics is paramount to unveiling the role of such loci in psoriasis and disentangling its complex nature. In this review, we aim to elucidate the main findings in this field and integrate our discussion with gold-standard techniques in molecular biology-i.e., Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-and high-throughput technologies. These tools are vital to understanding how disease risk loci affect gene expression in psoriasis, which is crucial in identifying new targets for personalized treatments in advanced precision medicine.

Serum Beta-Defensin-2 is a biomarker for psoriasis but not subclinical atherosclerosis: Role of IL17a, PI-3 kinase and Rac1

Background

Beta-defensins (BDs) are antimicrobial peptides secreted upon epithelial injury. Both chemotactic and antimicrobial properties of BDs function as initial steps in host defense and prime the adaptive immune system in the body. Psoriasis, a chronic immune-mediated inflammatory disease, has both visible cutaneous manifestations as well as known associations with higher incidence of cardiometabolic complications and vascular inflammation.

Objectives

We aimed to investigate the circulating expression of beta-defensin-2 (BD2) in psoriasis at baseline compared to control subjects, along with changes in BD2 levels following biologic treatment at one-year. The contribution of BD2 to subclinical atherosclerosis is also assessed. In addition, we have sought to unravel signaling mechanisms linking inflammation with BD2 expression.

Methods

Multimodality imaging as well inflammatory biomarker assays were performed in biologic naïve psoriasis (n=71) and non-psoriasis (n=53) subjects. A subset of psoriasis patients were followed for one-year after biological intervention (anti-Tumor Necrosis Factor-α (TNFα), n=30; anti-Interleukin17A (IL17A), n=21). Measurements of circulating BD2 were completed by Enzyme-Linked Immunosorbent Assay (ELISA). Using HaCaT transformed keratinocytes, expression of BD2 upon cytokine treatment was assessed by quantitative polymerase chain reaction (qPCR) and ELISA.

Results

Herein, we confirm that human circulating BD2 levels associate with psoriasis, which attenuate upon biologic interventions (anti-TNFα, anti-IL-17A). A link between circulating BD2 and sub-clinical atherosclerosis markers was not observed. Furthermore, we demonstrate that IL-17A-driven BD2 expression occurs in a Phosphatidylinositol 3-kinase (PI3-kinase) and Rac1 GTPase-dependent manner.

Conclusions

Our findings expand on the potential role of BD2 as a tractable biomarker in psoriasis patients and describes the role of an IL-17A-PI3-kinase/Rac signaling axis in regulating BD2 levels in keratinocytes.

The impact of dietary interventions in psoriatic arthritis

PURPOSE OF REVIEW

Psoriatic arthritis (PsA) is a common form of inflammatory arthritis that affects people with psoriasis. Both psoriasis and PsA are associated with metabolic diseases including obesity, hypertension, hyperlipidaemia, diabetes mellitus, fatty liver disease, and cardiovascular disease including myocardial infarction. Dietary interventions for psoriatic disease have been of great interest, particularly among patients with PsA.

RECENT FINDINGS

Herein, we review the evidence for dietary intervention in psoriatic arthritis. To date, weight loss among patients who are obese has the greatest evidence for benefit. We also examine the evidence for fasting, nutrient supplementation, and specific diets as adjunct therapeutic strategies.

SUMMARY

While the data do not clearly support a single dietary intervention across the disease, weight loss among those who are obese results in improved PsA disease activity and physical function. Additional studies are needed to better understand the impact of diet on psoriatic arthritis.

Pharmacogenomics on the Treatment Response in Patients with Psoriasis: An Updated Review

The efficacy and the safety of psoriasis medications have been proved in trials, but unideal responses and side effects are noted in clinical practice. Genetic predisposition is known to contribute to the pathogenesis of psoriasis. Hence, pharmacogenomics gives the hint of predictive treatment response individually. This review highlights the current pharmacogenetic and pharmacogenomic studies of medical therapy in psoriasis. HLA-Cw*06 status remains the most promising predictive treatment response in certain drugs. Numerous genetic variants (such as ABC transporter, DNMT3b, MTHFR, ANKLE1, IL-12B, IL-23R, MALT1, CDKAL1, IL17RA, IL1B, LY96, TLR2, etc.) are also found to be associated with treatment response for methotrexate, cyclosporin, acitretin, anti-TNF, anti-IL-12/23, anti-IL-17, anti-PDE4 agents, and topical therapy. Due to the high throughput sequencing technologies and the dramatic increase in sequencing cost, pharmacogenomic tests prior to treatment by whole exome sequencing or whole genome sequencing may be applied in clinical in the future. Further investigations are necessary to manifest potential genetic markers for psoriasis treatments.

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.

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.

Nanotechnology-based medicinal products and patents: a promising way to treat psoriasis

Psoriasis is an autoimmune skin disorder that is characterised by chronic inflammation and erythematous scaly patches. It has a significant impact on the patient's quality of life and can cause psychological stress. There are several aspects which cause psoriasis for instance, environmental issues, immune disorders, bacterial infections, and genetic issues. Plentiful therapeutic means or treatments are accessible, but not any of them can completely and effectively cure psoriasis without hindering patient compliance. Hence, it becomes challenging to discover a new drug moiety or any drug delivery method to cure psoriasis. Conventional treatment of psoriasis involves anti-inflammatory agents, immune suppressants, phototherapy, and biologic treatment, those were given in different forms such as topical, oral, or systemic formulations, but these all were unsuccessful to accomplish complete reduction of psoriasis as well as causing adverse side effects. In terms of dose frequency, doses, efficacy, and side effects, nanotechnology-based new formulations are the most promising prospects for addressing the challenges and limits associated with present psoriasis formulations. Hence, our major goal of this review is to present various advanced nanotechnological approaches for effective topical treatment of psoriasis. In short, nano-formulations continue to be formed as very promising modality in the treatment of psoriasis as they suggest improved penetration, targeted delivery, increased safety, and efficacy.

New Insights on Juvenile Psoriatic Arthritis

Juvenile psoriatic arthritis (JPsA) is a relatively rare condition in childhood as it represents approximately 5% of the whole Juvenile Idiopathic Arthritis (JIA) population. According to International League of Associations of Rheumatology (ILAR) classification, JPsA is defined by the association of arthritis and psoriasis or, in the absence of typical psoriatic lesions, with at least two of the following: dactylitis, nail pitting, onycholysis or family history of psoriasis in a first-degree relative. However, recent studies have shown that this classification system could conceal more homogeneous subgroups of patients differing by age of onset, clinical characteristics and prognosis. Little is known about genetic factors and pathogenetic mechanisms which distinguish JPsA from other JIA subtypes or from isolated psoriasis without joint involvement, especially in the pediatric population. Specific clinical trials testing the efficacy of biological agents are lacking for JPsA, while in recent years novel therapeutic agents are emerging in adults. In this review, we summarize the clinical features and the current evidence on pathogenesis and therapeutic options for JPsA in order to provide a comprehensive overview on the clinical management of this complex and overlapping entity in childhood.

Early-Onset Versus Late-Onset Psoriasis: A Comparative Study of Clinical Variables, Comorbidities, and Association with HLA CW6 in a Tertiary Care Center

Background:

Psoriasis is a chronic inflammatory diseaseresulting from a complex interplay of genetic and environmental factors affecting the skin, nail and joints. Two distinct types of psoriasis are said to exist (i) early onset psoriasis (EOP), beginning before the age of 40 years and (ii) late onset psoriasis (LOP), beginning ≥40 years; with the presence of Human lymphocyte antigen (HLA) Cw6, present in majority of patients with early onset. Several studies demonstrated clinical and genetic differences between EOP and LOPamong European and East Asian populations. Lack of similar study in the Indian population has prompted us to undertake the present work.

Aims and Objectives:

(i) To compare the clinical patterns of early onset and late onset psoriasisin patients attending the Dermatology outpatientdepartment (OPD) and admitted in the in-patient department (IPD). (ii) To analyze the association age of onset with presence of HLA Cw6.

Materials and Methods:

It was an institution-based, descriptive, cross-sectional study. Consecutive patients with psoriasis at the OPD and IPD of the department of Dermatology during the study period, were recruited in the study after obtaining informed consents. Detailed history was obtained regarding the disease, co-morbidities and complications. Through physical examination was carried out, PASI was calculated and blood samples were drawn fromconsenting adult patients (age>/=18 years) to study the presence of Cw6.

Results:

The study population (n=250) wasbroadly divided into “Early onset psoriasis(EOP)” (n=138) and Late onset psoriasis (LOP)” (n=112).Significant higher occurrence of positive family history, nail involvement and koebnerization were found in EOP, but such differences were absent considering the types, patterns, joint involvement, severity and HLACW6 positivity.

Conclusion:

This study supports the concept of two subtypes of psoriasis based on age of onset showing different clinical and evolutionary features.

Autoimmunity in psoriatic arthritis: pathophysiological and clinical aspects

Psoriatic arthritis (PsA) is an underdiagnosed entity with a broad impact on the quality of life. Although the pathogenesis is largely unknown, autoimmune footprints of the inflammation in PsA have increasingly been recognized. Most of the genetic variation predisposing to PsA is mapped to the class I major histocompatibility complex (MHC) region and shared by a variety of autoimmune diseases. Polymorphisms in the genes IL12B, IL23R, IL13, TNIP1, TRAF3IP2, TYK2, and many others explain the non- HLA genetic risk with little known functional consequences. Entheseal and synovial cellular infiltrate with oligoclonal CD8+ T cells and occasional germinal centers, loss of regulatory T cell function, and specific autoantibodies such as anti-PsA peptide, anti-LL-37, and anti-ADAMTSL5 are the immunopathological findings suggestive of autoimmunity. These were supported by clinical observations of autoimmune multimorbidity and treatment response to calcineurin/mTOR and co-stimulation inhibition.

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.

Gene Expression Profiling of Monozygotic Twins Affected by Psoriatic Arthritis

Introduction

Psoriatic Arthritis (PsA) is a multifactorial disease, where the relative burden of genetic, epigenetic and environmental factors in clinical course and damage accrual is not yet definitively clarified. In clinical practice, there is a real need for useful candidate biomarkers in PsA diagnosis and disease progression, by exploring its underlying transcriptomic and epigenomic mechanisms. This work aims to profile the transcriptome in monozygotic (MZ) twins with psoriatic arthritis (PsA) highly concordant for clinical presentation, but discordant for the radiographic outcomes’ severity.

Methods

We describe i) the clinical case of two MZ twins; ii) their comparative gene expression profiling (HTA 2.0 Affymetrix) and iii) signal pathways and pathophysiological processes in which differentially expressed genes are involved (in silico analysis by the IPA software, QIAGEN).

Results

One hundred sixty-three transcripts and 36 coding genes (28 up and 8 down) were differentially expressed between twins, and in the brother with the most erosive form, the transcriptomic profiling highlights the overexpression of genes known to be involved in immunomodulatory processes and on a broad spectrum of PsA manifestations.

Discussion

Twins’ clinical cases are still a gold mine in medical research: twin brothers are ideal experimental models in estimating the relative importance of genetic versus nongenetic components as determinants of complex phenotypes, non-Mendelian and multifactorial diseases as PsA.

Using functional genomics to advance the understanding of psoriatic arthritis

Psoriatic arthritis (PsA) is a complex disease where susceptibility is determined by genetic and environmental risk factors. Clinically, PsA involves inflammation of the joints and the skin, and, if left untreated, results in irreversible joint damage. There is currently no cure and the few treatments available to alleviate symptoms do not work in all patients. Over the past decade, genome-wide association studies (GWAS) have uncovered a large number of disease-associated loci but translating these findings into functional mechanisms and novel targets for therapeutic use is not straightforward. Most variants have been predicted to affect primarily long-range regulatory regions such as enhancers. There is now compelling evidence to support the use of chromatin conformation analysis methods to discover novel genes that can be affected by disease-associated variants. Here, we will review the studies published in the field that have given us a novel understanding of gene regulation in the context of functional genomics and how this relates to the study of PsA and its underlying disease mechanism.

Relationship Between Interleukin-6 -174G/C Genetic Variant and Efficacy of Methotrexate Treatment in Psoriatic Arthritis Patients

Introduction

The purpose of the study was to investigate whether single-nucleotide polymorphisms (SNPs) IL-6 −174 G/C and IL-6R Asp358Ala are associated with susceptibility to psoriatic arthritis (PsA) or affect response to treatment with methotrexate (MTX).

Patients and Methods

Seventy-four patients diagnosed with PsA and qualified for MTX treatment were enrolled to the study. The control group consisted of 120 healthy individuals. Polymorphisms IL-6 −174 G/C and IL-6R Asp358Ala were genotyped using a polymerase chain reaction (PCR) amplification employing LightSNiP assays.

Results

A significant association between the IL-6 −174 CC genotype and an improved clinical outcome of MTX therapy was observed. A good response was more frequently observed among PsA patients bearing the IL-6 −174 CC genotype than patients with the GC or GG genotypes (P = 0.007). On the other hand, patients carrying the IL-6 −174 GC genotype less frequently responded to MTX treatment as compared to patients with other genotypes (P = 0.006). With respect to the IL-6R Asp358Ala SNP, there were no significant differences in genotype and allelic frequencies in relation to clinical outcome of MTX treatment. No association was found between the IL-6 −174 G/C or IL-6R Asp358Ala SNPs and PsA susceptibility.

Conclusion

Results from this study provide evidence that the IL-6 −174 G/C polymorphism might influence efficacy of MTX treatment.

New JAK inhibitors for the treatment of psoriasis and psoriatic arthritis

Psoriasis is a common inflammatory skin disease that can be associated with various pathological conditions among which arthritis is a frequent comorbidity. Based on the current pathogenetic model, development of psoriasis is mainly driven by the IL-23/IL-17A axis. Though the therapeutic armamentarium is expanding in the latest years, new therapies are needed because of the lack or loss of response or intolerance/contraindication to the currently approved drugs. The most recently developed drugs for the treatment of psoriasis and psoriatic arthritis specifically target cytokines, cytokine receptors, and intracellular signaling transducers that are involved in the pathogenesis of psoriasis. Janus kinase (JAK) pathway transduces signals of multiple cytokines, such as TNF-α, IL-23, IL-12, IFN, IL-6, IL-17, that have resulted crucial in the induction and maintenance of psoriasis inflammation. Thereby, JAK-1, JAK-3, TYK-2 belonging to the JAK family, have been identified as valid therapeutic targets in the treatment of psoriasis. Nowadays, different JAK inhibitors have been investigated in clinical trials showing promising results in terms of efficacy and safety. In this review, we systematically collected publications and data related to JAK inhibitors used in psoriasis and psoriatic arthritis providing the state-of-the-art on this new class of molecules in the treatment of these diseases.

Indoor salt water baths followed by artificial ultraviolet B light for chronic plaque psoriasis

BACKGROUND

Chronic plaque psoriasis is an immune-mediated, chronic, inflammatory skin disease, which can impair quality of life and social interaction. Disease severity can be classified by the psoriasis area and severity index (PASI) score ranging from 0 to 72 points. Indoor artificial salt bath with or without artificial ultraviolet B (UVB) light is used to treat psoriasis, simulating sea bathing and sunlight exposure; however, the evidence base needs clear evaluation.

OBJECTIVES

To assess the effects of indoor (artificial) salt water baths followed by exposure to artificial UVB for treating chronic plaque psoriasis in adults.

SEARCH METHODS

We searched the following databases up to June 2019: the Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We also searched five trial registers, and checked the reference lists of included studies, recent reviews, and relevant papers for further references to relevant trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of salt bath indoors followed by exposure to artificial UVB in adults who have been diagnosed with chronic plaque type psoriasis. We included studies reporting between-participant data and within-participant data. We evaluated two different comparisons: 1) salt bath + UVB versus other treatment without UVB; eligible comparators were exposure to psoralen bath, psoralen bath + artificial ultraviolet A UVA) light, topical treatment, systemic treatment, or placebo, and 2) salt bath + UVB versus other treatment + UVB or UVB only; eligible comparators were exposure to bath containing other compositions or concentrations + UVB or UVB only.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We used GRADE to assess the certainty of the evidence. The primary efficacy outcome was PASI-75, to detect people with a 75% or more reduction in PASI score from baseline. The primary adverse outcome was treatment-related adverse events requiring withdrawal. For the dichotomous variables PASI-75 and treatment-related adverse events requiring withdrawal, we estimated the proportion of events among the assessed participants. The secondary outcomes were health-related quality of life using the Dermatology Life Quality Index, (DLQI) pruritus severity measured using a visual analogue scale, time to relapse, and secondary malignancies.

MAIN RESULTS

We included eight RCTs: six reported between-participant data (2035 participants; 1908 analysed), and two reported within-participant data (70 participants, 68 analysed; 140 limbs; 136 analysed). One study reported data for the comparison salt bath with UVB versus other treatment without UVB; and eight studies reported data for salt bath with UVB versus other treatment with UVB or UVB only. Of these eight studies, only five reported any of our pre-specified outcomes and assessed the comparison of salt bath with UVB versus UVB only. The one included trial that assessed salt bath plus UVB versus other treatment without UVB (psoralen bath + UVA) did not report any of our primary outcomes. The mean age of the participants ranged from 41 to 50 years of age in 75% of the studies. None of the included studies reported on the predefined secondary outcomes of this review. We judged seven of the eight studies as at high risk of bias in at least one domain, most commonly performance bias. Total trial duration ranged between at least two months and up to 13 months. In five studies, the median participant PASI score at baseline ranged from 15 to 18 and was balanced between treatment arms. Three studies did not report PASI score. Most studies were conducted in Germany; all were set in Europe. Half of the studies were multi-centred (set in spa centres or outpatient clinics); half were set in a single centre in either an unspecified settings, a psoriasis daycare centre, or a spa centre. Commercial spa or salt companies sponsored three of eight studies, health insurance companies funded another, the association of dermatologists funded another, and three did not report on funding. When comparing salt bath plus UVB versus UVB only, two between-participant studies found that salt bath plus UVB may improve psoriasis when measured using PASI 75 (achieving a 75% or more reduction in PASI score from baseline) (risk ratio (RR) 1.71, 95% confidence interval (CI) 1.24 to 2.35; 278 participants; low-certainty evidence). Assessment was conducted at the end of treatment, which was equivalent to six to eight weeks after start of treatment. The two trials which contributed data for the primary efficacy outcome were conducted by the same group, and did not blind outcome assessors. The German Spas Association funded one of the trials and the funding source was not stated for the other trial. Two other between-participant studies found salt bath plus UVB may make little to no difference to outcome treatment-related adverse events requiring withdrawal compared with UVB only (RR 0.96, 95% CI 0.35 to 2.64; 404 participants; low-certainty evidence). One of the studies reported adverse events, but did not specify the type of events; the other study reported skin irritation. One within-participant study found similar results, with one participant reporting severe itch immediately after Dead Sea salt soak in the salt bath and UVB group and two instances of inadequate response to phototherapy and conversion to psoralen bath + UVA reported in the UVB only group (low-certainty evidence).

AUTHORS' CONCLUSIONS

Salt bath with artificial ultraviolet B (UVB) light may improve psoriasis in people with chronic plaque psoriasis compared with UVB light treatment alone, and there may be no difference in the occurrence of treatment-related adverse events requiring withdrawal. Both results are based on data from a limited number of studies, which provided low-certainty evidence, so we cannot draw any clear conclusions. The reporting of our pre-specified outcomes was either non-existent or limited, with a maximum of two studies reporting a given outcome. The same group conducted the two trials which contributed data for the primary efficacy outcome, and the German Spas Association funded one of these trials. We recommend further RCTs that assess PASI-75, with detailed reporting of the outcome and time point, as well as treatment-related adverse events. Risk of bias was an issue; future studies should ensure blinding of outcome assessors and full reporting.

Quantifying Differences in Heritability among Psoriatic Arthritis (PsA), Cutaneous Psoriasis (PsC) and Psoriasis vulgaris (PsV)

Chronic plaque psoriasis and psoriatic arthritis are multifactorial inter-related diseases with strong genetic contributions. Better elucidation of the heritability of psoriatic disease subsets is important for identifying novel genes, risk stratification and potential clinical applications. In this study, we used two mixed-effect modelling methodologies to assess the additive contribution of common single nucleotide polymorphisms from genome-wide association studies to estimate the heritability of cutaneous psoriasis, psoriasis vulgaris and psoriatic arthritis. We found that cutaneous psoriasis and psoriatic arthritis both exhibit considerable heritability, with a greater contribution coming from cutaneous psoriasis.

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.

Functional significance of MAIT cells in psoriatic arthritis

BACKGROUND

Mucosal-associated invariant T (MAIT) cells are gaining more relevance for autoimmune diseases because of its (i) innate and adaptive immune response (ii) tissue homing properties (iii) production of IL-17A. These cells are predominantly CD8⁺ cells, because of its strong association with MHC-I. Tc17 CD8+/MAIT cells likely to have a critical role in psoriatic arthritis (PsA). Herein, we have explored pathological significance of MAIT cell in PsA.

METHODS

Peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) were collected from age/sex matched (n = 10 for each) PsA, rheumatoid arthritis (RA) and osteoarthritis patients (OA). Hi-D FACS studies were performed: (i) activated memory cells (CD3⁺CD45RO⁺) T cells were identified (ii) gating strategies were made to identity the MAIT (CD3⁺Vα7.2TCR⁺CD161^hi) cells, its phenotype pattern; and functional significance in respect to IL-17A production and responsiveness to human rIL-23. Anti CD3/CD28 ab cocktail was used to activate cells along with rIL-23 to culture and enrich the MAIT cells. The percentages of each cell population and the mean fluorescence intensity (MFI) were analyzed using Flow Jo software.

RESULTS

MAIT cells were enriched in synovial fluid of PsA (4.29 ± 0.82%) compared to PBMC (1.04 ± 0.71). With stimulation, SFMC MAIT cells produced significantly more IL-17A (32.66 ± 4.01%) compared to that of RA (23.93 ± 2.81%, p < 0.05) and OA (5.02 ± 0.16%, p < 0.05). MAIT cells were predominantly CD8⁺ (>80%). Significant upregulation of IL-23R was noted in synovial fluid MAIT cells of PsA (24.97 ± 2.33%, p < 0.001) and RA (21.93 ± 2.29%, p < 0.001) compared to that of OA (2.13 ± 2.29). This IL-23R was functionally active as evidenced by profound mitotic effect in presence of rIL-23.

CONCLUSION

MAIT cells are poly functional; produce multiple cytokines (IL-17A, IFN-γ, TNF-α). Here, we demonstrated synovial fluid MAIT cells as a major source of IL-17A and majority of MAIT cells were CD8⁺. Functionally active IL-23R on these migrated MAIT cells brings a new dimension. They may not need MR1 associated activation rather lesional IL-23 in the synovium can independently regulate these critical Tc17 CD8⁺ MAIT cells. Thus, these cells likely to be a part of the IL-23/IL-17A cytokine network and play a critical role in the pathogenesis of PsA.

Epigenome-wide analysis of sperm cells identifies IL22 as a possible germ line risk locus for psoriatic arthritis

Psoriasis and its associated inflammatory arthritis, psoriatic arthritis (PsA), have a clear heritable component, but a large proportion of the heritable risk remains unexplained by gene sequence variation. This study aimed to determine if epigenetic factors contribute to the missing heritability in psoriatic disease. DNA methylation profiling was performed on sperm cells from 23 probands with psoriasis without PsA (PsC), 13 PsA probands, and 18 unaffected controls. Differentially methylated CpGs and regions (DMRs) were identified and validated by pyrosequencing. Underlying AluY and copy number variation (CNV) in the HCG26 and IL22 genes, respectively, were assessed by genotyping. Array, subject's age, age of psoriasis onset, psoriasis severity, and medication usage were found to influence methylation at many genes and were included as covariates in the analysis. Between PsC probands vs. controls, 169 DMRs were found; 754 DMRs were found between PsA probands vs. controls, and 86 between PsA and PsC probands (adjusted p<0.05). Differences in methylation across DMRs were generally subtle (<10%) but correlated well with pyrosequencing. Biological inference prioritized notable DMRs associated with skin disease (SIGLEC14, JAM3, PCOLCE, RXRB), skin and/or joint disease (MBP, OSBPL5, SNORD115, HCG26), and joint disease (IL22, ELF5, PPP2R2D, PTPRN2, HCG26). Hypermethylation of the DMR within the first exon of arthritis-associated IL22 showed significant correlation (rho = 0.34, 95% CI 0.06-0.57, p = 0.01) between paired sperm and blood samples, independent of a CNV within the same region. Further studies are needed to rule out underlying genetic causes and determine if these represent heritable, constitutional epimutations, or are the result of exposure of germ cells to endogenous or exogenous environmental factors.

MiR-146a-5p Expression in Peripheral CD14⁺ Monocytes from Patients with Psoriatic Arthritis Induces Osteoclast Activation, Bone Resorption, and Correlates with Clinical Response

In psoriatic arthritis (PsA), progressive bone destruction is mediated by monocyte-derived osteoclasts. MicroRNAs (miRNAs) regulate many pathophysiological processes; however, their function in PsA patient monocytes has not been examined. This study aims to address whether specific miRNAs in CD14⁺ monocytes and monocyte-derived osteoclasts cause active osteoclastogenesis in PsA patients. Candidate miRNAs related to monocyte activation (miR-146a-5p, miR-146b-5p and miR-155-5p) were measured in circulatory CD14⁺ monocytes collected from 34 PsA patients, 17 psoriasis without arthritis (PsO) patients, and 34 normal controls (NCs). CD14⁺ monocytes were cultured with media containing TNF-α and RANKL to differentiate into osteoclasts. Osteoclast differentiation and bone resorption were measured by TRAP immunostaining and dentin slice resorption, respectively. The results showed that the miR-146a-5p expression was higher in PsA patient-derived CD14⁺ monocytes compared to PsO and NCs. Activation and bone resorption were selectively enhanced in osteoclasts from PsA patients, but both were abrogated by RNA interference against miR-146a-5p. More importantly, after clinical improvement using biologics, the increased miR-146a-5p expression in CD14⁺ monocytes from PsA patients was selectively abolished, and associated with blood CRP level. Our findings indicate that miR-146a-5p expression in CD14⁺ monocytes derived from PsA patients correlates with clinical efficacy, and induction of osteoclast activation and bone resorption.

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.

Long Non-Coding RNAs Play a Role in the Pathogenesis of Psoriatic Arthritis by Regulating MicroRNAs and Genes Involved in Inflammation and Metabolic Syndrome

Psoriatic arthritis (PsA) is an inflammatory arthritis, characterized by inflammation of entheses and synovium, leading to joint erosions and new bone formation. It affects 10-30% of patients with psoriasis, and has an estimated prevalence of approximately 1%. PsA is considered to be primarily an autoimmune disease, driven by autoreactive T cells directed against autoantigens present in the skin and in the joints. However, an autoinflammatory origin has recently been proposed. Long noncoding RNAs (lncRNAs) are RNAs more than 200 nucleotides in length that do not encode proteins. LncRNAs play important roles in several biological processes, including chromatin remodeling, transcription control, and post-transcriptional processing. Several studies have shown that lncRNAs are expressed in a stage-specific or lineage-specific manner in immune cells that have a role in the development, activation, and effector functions of immune cells. LncRNAs are thought to play a role in several diseases, including autoimmune disorders. Indeed, a few lncRNAs have been identified in systemic lupus erythematosus, rheumatoid arthritis, and psoriasis. Although several high-throughput studies have been performed to identify lncRNAs, their biological and pathological relevance are still unknown, and most transcriptome studies in autoimmune diseases have only assessed protein-coding transcripts. No data are currently available on lncRNAs in PsA. Therefore, by microarray analysis, we have investigated the expression profiles of more than 50,000 human lncRNAs in blood samples from PsA patients and healthy controls using Human Clariom D Affymetrix chips, suitable to detect rare and low-expressing transcripts otherwise unnoticed by common sequencing methodologies. Network analysis identified lncRNAs targeting highly connected genes in the PsA transcriptome. Such genes are involved in molecular pathways crucial for PsA pathogenesis, including immune response, glycolipid metabolism, bone remodeling, type 1 interferon, wingless related integration site, and tumor necrosis factor signaling. Selected lncRNAs were validated by RT-PCR in an expanded cohort of patients. Moreover, modulated genes belonging to meaningful pathways were validated by RT-PCR in PsA PBMCs and/or by ELISA in PsA sera. The findings indicate that lncRNAs are involved in PsA pathogenesis by regulating both microRNAs and genes and open new avenues for the identification of new biomarkers and therapeutical targets.

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.

Exome-wide association study reveals novel psoriasis susceptibility locus at TNFSF15 and rare protective alleles in genes contributing to type I IFN signalling

Psoriasis is a common inflammatory skin disorder for which multiple genetic susceptibility loci have been identified, but few resolved to specific functional variants. In this study, we sought to identify common and rare psoriasis-associated gene-centric variation. Using exome arrays we genotyped four independent cohorts, totalling 11 861 psoriasis cases and 28 610 controls, aggregating the dataset through statistical meta-analysis. Single variant analysis detected a previously unreported risk locus at TNFSF15 (rs6478108; P = 1.50 × 10-8, OR = 1.10), and association of common protein-altering variants at 11 loci previously implicated in psoriasis susceptibility. We validate previous reports of protective low-frequency protein-altering variants within IFIH1 (encoding an innate antiviral receptor) and TYK2 (encoding a Janus kinase), in each case establishing a further series of protective rare variants (minor allele frequency < 0.01) via gene-wide aggregation testing (IFIH1: pburden = 2.53 × 10-7, OR = 0.707; TYK2: pburden = 6.17 × 10-4, OR = 0.744). Both genes play significant roles in type I interferon (IFN) production and signalling. Several of the protective rare and low-frequency variants in IFIH1 and TYK2 disrupt conserved protein domains, highlighting potential mechanisms through which their effect may be exerted.

KIF3A and IL-4 are disease-specific biomarkers for psoriatic arthritis susceptibility

To date, the genes associated with Psoriatic Arthritis (PsA) are principally involved in inflammation, immune response and epidermal differentiation, without any information about the relationship between disease and bone metabolism genes. Our work was focused on 5q31 locus, which contains several genetic variants significantly associated with PsA. The study involved 1526 subjects (500 PsA, 426 PsV, 600 controls). The region was evaluated by selecting and genotyping the SNPs of interest by Real Time PCR and direct sequencing. The results were subjected to biostatistic and bioinformatic analysis.

The case-control study highlighted a significant association between KIF3A/IL-4 and PsA, but not with PsV (Psoriasis Vulgaris) patients. In addition, the haplotype analysis revealed two haplotypes significantly associated with PsA susceptibility. The Linkage Disequilibrium (LD) study showed the presence of a specific block in high LD within 132,692,628-132,737,638 bp of 5q31, giving additional evidence of specific association of the 5q31 region in PsA patients. Moreover, KIF3A expression was assessed by immunohistochemistry assays which showed a marked and significant difference of KIF3A expression between pathological and normal tissues. Our analysis described KIF3A and IL-4 as novel susceptibility genes for PsA, suggesting a clear implication of bone metabolism genes in the disease etiopathogenesis.

Impact of metabolic status on the incidence of psoriasis: a Korean nationwide cohort study

Growing evidence suggests that obesity is a risk factor for incident psoriasis. This study was aimed to evaluate the association of obesity and metabolic status with the incidence of psoriasis. A total of 418,057 adults were followed-up using a nationwide prospective cohort study in Korea. Participants were stratified based on the body mass index categories and metabolic condition. During the follow-up visit, 11054 (2.6%) cases were found to have psoriasis. Diabetes, hypertension, hyperlipidemia, and obesity were all found to be risk factors for incident psoriasis. The metabolically unhealthy non-obese (MUNO) subjects (hazard ratio [HR], 1.29; 95% confidence interval [CI], 1.22-1.37) and metabolically unhealthy obese subjects (MUO; HR, 1.33; 95% CI, 1. 26-1.41) had a significantly higher risk of psoriasis incidence as compared to metabolically healthy non-obese subjects. The risk of psoriasis development was found to be high among the MUNO and MUO subjects in both sexes and all age groups. In conclusion, the metabolic health status was significantly associated with an increased risk of psoriasis in both obese and non-obese individuals. However, further studies are needed to evaluate whether the control of metabolic parameters can lower the incidence of psoriasis.

CARD14 alterations in Tunisian patients with psoriasis and further characterization in European cohorts

BACKGROUND

Rare highly penetrant gain-of-function mutations in caspase recruitment domain family, member 14 (CARD14) can lead to psoriasis, a chronic inflammatory disease of the skin and other organs.

OBJECTIVES

To investigate the contribution of rare CARD14 variants to psoriasis in the Tunisian population and to expand knowledge of CARD14 variants in the European population.

METHODS

CARD14 coding exons were resequenced in patients with psoriasis and controls from Tunisia and Europe, including 16 European cases with generalized pustular psoriasis (GPP). Novel variants were evaluated for their effect on nuclear factor (NF)-κB signalling.

RESULTS

Rare variants in CARD14 were significantly enriched in Tunisian cases compared with controls. Three were collectively found in 5% of Tunisian cases, and all affected the N-terminal region of the protein harbouring its caspase recruitment domain or coiled-coil domain. These variants were c.349G>A (p.Gly117Ser), c.205C>T (p.Arg69Trp) and c.589G>A (p.Glu197Lys). c.589G>A (p.Glu197Lys) led to upregulation of NF-κB activity in a similar manner to that of previously described psoriasis-associated mutations. p.Arg69Trp led to sevenfold downregulation of NF-κB activity. One Tunisian case harboured a c.1356+5G>A splice alteration that is predicted to lead to loss of exon 9, which encodes part of the coiled-coil domain. No cases of GPP harboured an interleukin-36RN mutation, but one of 16 cases of GPP with a family history of psoriasis vulgaris harboured a c.1805C>T (p.Ser602Leu) mutation in CARD14.

CONCLUSIONS

These observations provide further insights into the genetic basis of psoriasis in the Tunisian population and provide functional information on novel CARD14 variants seen in cases from Tunisia and other populations.

Gene Expression Profiling in Peripheral Blood Cells and Synovial Membranes of Patients with Psoriatic Arthritis

Background

Psoriatic arthritis (PsA) is an inflammatory arthritis whose pathogenesis is poorly understood; it is characterized by bone erosions and new bone formation. The diagnosis of PsA is mainly clinical and diagnostic biomarkers are not yet available. The aim of this work was to clarify some aspects of the disease pathogenesis and to identify specific gene signatures in paired peripheral blood cells (PBC) and synovial biopsies of patients with PsA. Moreover, we tried to identify biomarkers that can be used in clinical practice.

Methods

PBC and synovial biopsies of 10 patients with PsA were used to study gene expression using Affymetrix arrays. The expression values were validated by Q-PCR, FACS analysis and by the detection of soluble mediators.

Results

Synovial biopsies of patients showed a modulation of approximately 200 genes when compared to the biopsies of healthy donors. Among the differentially expressed genes we observed the upregulation of Th17 related genes and of type I interferon (IFN) inducible genes. FACS analysis confirmed the Th17 polarization. Moreover, the synovial trascriptome shows gene clusters (bone remodeling, angiogenesis and inflammation) involved in the pathogenesis of PsA. Interestingly 90 genes are modulated in both compartments (PBC and synovium) suggesting that signature pathways in PBC mirror those of the inflamed synovium. Finally the osteoactivin gene was upregulared in both PBC and synovial biopsies and this finding was confirmed by the detection of high levels of osteoactivin in PsA sera but not in other inflammatory arthritides.

Conclusions

We describe the first analysis of the trancriptome in paired synovial tissue and PBC of patients with PsA. This study strengthens the hypothesis that PsA is of autoimmune origin since the coactivity of IFN and Th17 pathways is typical of autoimmunity. Finally these findings have allowed the identification of a possible disease biomarker, osteoactivin, easily detectable in PsA serum.

Crossreactive autoantibodies directed against cutaneous and joint antigens are present in psoriatic arthritis

Background

Psoriatic arthritis (PsA) is a chronic inflammatory disease of unknown origin, characterized by erosions and new bone formation. Diagnosis of PsA is mainly clinical and there are no biomarkers available. Moreover in PsA autoantibodies have not been described so far. Indeed an autoimmune origin has been suggested but never proven. Aim of the study was to investigate the possible presence of autoantibodies typically associated with PsA.

Methods

We used pooled IgG immunoglobulins derived from 30 patients with PsA to screen a random peptide library in order to identify disease relevant autoantigen peptides.

Results

Among the selected peptides, one was recognised by nearly all the patients’ sera. The identified peptide (PsA peptide: TNRRGRGSPGAL) shows sequence similarities with skin autoantigens, such as fibrillin 3, a constituent of actin microfibrils, desmocollin 3, a constituent of the desmosomes and keratin 78, a component of epithelial cytoskeleton. Interestingly the PsA peptide shares homology with the nebulin-related anchoring protein (N-RAP), a protein localized in the enthesis (point of insertion of a tendon or ligament to the bone), which represents the first affected site during early PsA. Antibodies affinity purified against the PsA peptide recognize fibrillin, desmocollin, keratin and N-RAP. Moreover antibodies directed against the PsA peptide are detectable in 85% of PsA patients. Such antibodies are not present in healthy donors and are present in 13/100 patients with seroposive rheumatoid arthritis (RA). In seronegative RA these antibodies are detectable only in 3/100 patients.

Conclusions

Our results indicate that PsA is characterized by the presence of serum autoantibodies crossreacting with an epitope shared by skin and joint antigens.

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.

Deletion of late cornified envelope genes, LCE3C_LCE3B-del, is not associated with psoriatic arthritis in Tunisian patients

A deletion of two genes from the late cornified envelope (LCE), LCE3B and LCE3C within epidermal differentiation complex on chromosome 1 was shown to be associated with both psoriasis and psoriatic arthritis (PsA) in several populations. To assess whether this deletion may contribute to the genetic predisposition to PsA in Tunisia, a total of 73 patients with PsA and 120 healthy matched controls were screened for the deletion, LCE3C_LCE3B-del, and its tag SNP, rs4112788. We also evaluated a possible relationship between PSORS1 and LCE3C_LCE3B-del through genotyping two proxy markers to HLA-C (rs12191877 and rs2073048). Our results did not provide evidence for association between the LCE3C_LCE3B-del nor the rs4112788 and the PsA. Similarly, no significant epistatic effect was observed. Our data suggest that The LCE deletion, previously identified in patients with psoriasis, is not of a major importance in the development of PsA in Tunisian patients supporting the current perception that different genetic risk factors contribute to skin and joint disease. However, these results need to be confirmed by additional large-scale studies of Tunisian PsA patients and controls.

Therapeutic strategies in psoriasis patients with psoriatic arthritis: focus on new agents

Psoriatic arthritis affects approximately 6-42 % of patients with psoriasis. It is useful for physicians or dermatologists managing psoriasis patients to be aware of how to concurrently manage the joint manifestations, as it is preferable and convenient to use a single agent in such patients. However, only certain therapies are effective for both. Systemic agents, which can be used for both skin and joint manifestations, include methotrexate and ciclosporin. For the group of biologic agents, the tumor necrosis factor inhibitors such as adalimumab, etanercept, infliximab, golimumab and certolizumab are effective. Ustekinumab is a more recently developed agent belonging to the group of anti-IL-12p40 antibodies and has been shown to be efficacious. Newer drugs in the treatment armamentarium that have shown efficacy for both psoriasis and psoriatic arthritis consist of the anti-IL-17 agent, secukinumab, and a phosphodiesterase-4 inhibitor, apremilast. The other anti-IL-17 agents, ixekizumab and brodalumab, as well as the oral Jak inhibitor, tofacitinib, have very limited but promising data. This review paper provides a good overview of the agents that can be used for the concurrent management of skin and joint psoriasis.

Advances in the genetics of spondyloarthritis and clinical implications

Spondyloarthritis (SpA) is a group of inflammatory rheumatic diseases whose main clinical feature is inflammation of the axial spine. Articular, periarticular, and extra-articular manifestations can also occur, depending on the type of spondyloarthritis. The most common clinical subsets of SpA are ankylosing spondylitis (AS) and psoriatic arthritis (PsA). SpA is a major health challenge given the propensity to affect young adults and the potential requirement for lifelong treatment. Although the precise etiology of SpA is unknown, there is mounting evidence that these diseases are a result of complex interplay of genetic, environmental, and immunological factors. In this review on SpA, we will discuss genetic variants with genome-wide significance, highlight potential clinical application of genetic variants, and discuss challenges in further elucidating the genetic basis of SpA.

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.

Effectiveness of conventional drug therapy of plaque psoriasis in the context of consensus guidelines: a prospective observational study in 150 patients

BACKGROUND

Evidence for superior outcome by adhering to therapy guidelines is imperative to their acceptance and adaptation for the optimal management of disease variants.

OBJECTIVE

Comparative study of prospective outcomes in simultaneous consideration of independent variables in groups of 150 patients of plaque psoriasis either treated adhering to or in digression of standard guidelines.

METHODS

The psoriasis area severity index (PASI) and the dermatology life quality index (DLQI), prior to and after three months of uninterrupted therapy were examined in treatment groups among 150 patients. Recovery rates of 75% or more in PASI were compared. Independent variables were also examined for their bearing on the outcome.

RESULTS

The vast majority was early onset disease phenotype. All three treatment regimens when administered in adherence to the guidelines yielded significantly superior rates of defined recovery both in PASI and DLQI. Compromise of the therapeutic outcome appeared in high stress profiles, obesity, female sex and alcohol, tobacco or smoking habit.

CONCLUSION

Conventional drug therapy of plaque psoriasis yields superior outcome by adhering to the consensus guidelines. Psychiatric address to stress must be integral and special considerations for phenotypic/syndromic variants is emphasized for effective therapy of psoriasis.

Emerging role for the killer-cell immunoglobulin-like receptors genotype, in the susceptibility of skin diseases

NK cells are a major group of immune cells responsible for the phenomenon of natural, innate cytotoxicity. One of the better studied receptors of human NK cells are killer cell immunoglobulin-like receptors (KIR) responsible for checking the presence of MHC class I molecules, which serve as their ligands. Although previously treated as specific for NK cells, nowadays these receptors are known to also occur on T cells. Genetics of KIR molecules is very complicated, what create a great variability of haplotypes in various populations world-wide. In addition, some KIR are known to recognize HLA-C (epitopes C1 or C2), HLA-B (Bw4) or HLA-A (A3 and/or A11) molecules. Therefore, this makes a huge diversity of reactions among individuals, depending on the presence or absence of given KIR and their ligands, hence differential susceptibility to several diseases, including various dermatoses. This paper underlines the important role of both KIR genotypes and HLA class I genes with reference to the various skin diseases.

Higher levels of autoantibodies targeting mutated citrullinated vimentin in patients with psoriatic arthritis than in patients with psoriasis vulgaris

Antibodies against citrullinated proteins/peptides (ACPAs), and especially antibodies targeting mutated citrullinated vimentin (anti-MCVs), are novel biomarkers of rheumatoid arthritis (RA). Whereas ACPAs are specific and sensitive markers for RA, there have hardly been any reports relating to ACPAs in psoriatic arthritis (PsA) or in psoriasis without joint symptoms (PsO). The aim of the present study was to investigate the prevalence of anti-MCVs in PsA and PsO. Serum anti-MCV titers were measured in 46 PsA and 42 PsO patients and in 40 healthy controls by means of a commercial enzyme-linked immunosorbent assay. The potential correlations of the serum autoantibody levels with several clinical and laboratory parameters were examined. The anti-MCV levels in the PsA patients were significantly higher than those in the PsO group. Among the clinical variables, the presence of tender knee joints and nail psoriasis was significantly associated with anti-MCV positivity in the PsA patients. Higher anti-MCV titers in the PsO patients were associated with a more severe disease course and with the early onset of psoriatic skin symptoms. Our results suggest that anti-MCVs can be used as novel markers in the diagnosis of PsA and in a subset of PsO patients.

Search for new molecular targets for anticytokine therapy of patients, suffering from the immune dependent skin disease — psoriasis

The authors describe the results of a study aimed at searching for new molecular targets for anticytokine therapy of patients with psoriasis. The authors examined 26 patients with psoriasis who were treated with such immune biologic substances as infliximab, ustekinumab, adalimumab and 10 healthy volunteers. They performed a quality and quantity analysis of the spectrum of protein molecules of cytokines (L-4, IL-6, IL-17, TNF-α and IL-20, IL-22, IL-31, IL-12, IL-11, IL-18) аs well as VEGF and ICAM-1 molecules in patients receiving the therapy with immune biologic substances before and after treatment using the methodology of the immune enzyme analysis and xMAP multiplex technology. The authors studied the correlation between the level of cytokine expression, on the one hand, and the occurrence and limitation of the disease, on the other hand. The obtained data are sufficient to conclude that the spectrum of molecules of IL6, IL20, IL22 anti-inflammatory cytokines аs well as VEGF and ICAM-1 molecules, for which pathogenic importance in case of psoriasis was revealed as a result of the study , may serve as a potential (new, additional) molecular target for anticytokine therapy of patients suffering with such an immune-dependent skin disease as psoriasis.

Functional role of IL-22 in psoriatic arthritis

INTRODUCTION

Interleukin-22 (IL-22) is a cytokine of IL-10 family with significant proliferative effect on different cell lines. Immunopathological role of IL-22 has been studied in rheumatoid arthritis (RA) and psoriasis. Here we are reporting the functional role of IL-22 in the inflammatory and proliferative cascades of psoriatic arthritis (PsA).

METHOD

From peripheral blood and synovial fluid (SF) of PsA (n = 15), RA (n = 15) and osteoarthritis (OA, n = 15) patients, mononuclear cells were obtained and magnetically sorted for CD3+ T cells. Fibroblast like synoviocytes (FLS) were isolated from the synovial tissue of PsA (n = 5), RA (n = 5) and OA (n = 5) patients. IL-22 levels in SF and serum were measured by enzyme linked immunosorbent assay (ELISA). Proliferative effect of human recombinant IL-22 (rIL-22) on FLS was assessed by MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, a yellow tetrazole) and CFSE dilution (Carboxyfluorescein succinimidyl ester) assays. Expression of IL-22Rα1 in FLS was determined by western blot.

RESULTS

IL-22 levels were significantly elevated in SF of PsA patients (17.75 ± 3.46 pg/ml) compared to SF of OA (5.03 ± 0.39 pg/ml), p < 0.001. In MTT and CFSE dilution assays, rIL-22 (MTT, OD: 1.27 ± 0.06) induced significant proliferation of FLS derived from PsA patients compared to media (OD: 0.53 ± 0.02), p < 0.001. In addition, rIL-22 induced significantly more proliferation of FLS in presence of TNF-α. IL-22Rα1 was expressed in FLS of PsA, RA and OA patients. Anti IL-22R antibody significantly inhibited the proliferative effect of rIL-22. Further we demonstrated that activated synovial T cells of PsA and RA patients produced significantly more IL-22 than those of OA patients.

CONCLUSION

SF of PsA patients have higher concentration of IL-22 and rIL-22 induced marked proliferation of PsA derived FLS. Moreover combination of rIL-22 and TNF-α showed significantly more proliferative effect on FLS. IL-22Rα1 was expressed in FLS. Successful inhibition of IL-22 induced FLS proliferation by anti IL-22R antibody suggests that blocking of IL-22/IL-22R interaction may be considered as a novel therapeutic target for PsA.