Prediction of Psoriatic Arthritis in Patients With Psoriasis Using DNA Methylation Profiles.

OBJECTIVE: Psoriatic arthritis (PsA) is an immune-mediated inflammatory arthritis, associated with psoriasis, that significantly increases morbidity and mortality risk. We currently lack the means of predicting which patients with psoriasis will develop PsA, and a large number of patients remain undiagnosed. Regulation of gene expression through DNA methylation can potentially trigger and maintain PsA pathophysiological processes. We aimed to identify DNA methylation markers that can predict which patients with psoriasis will develop PsA prior to the onset of musculoskeletal symptoms. METHODS: Genome-wide DNA methylation was assessed in blood samples from patients with psoriasis who went on to develop arthritis (converters) and patients with psoriasis who did not (biologic naive, matched for age, sex, psoriasis duration, and duration of follow-up). Methylation differences between converters and nonconverters were identified by a multivariate linear regression model including clinical covariates (age, sex, body mass index, smoking). Predictive performance of methylation markers was assessed by developing support vector machine classification models with and without the addition of clinical variables. RESULTS: We identified a set of 36 highly relevant methylation markers (false discovery rate: adjusted P < 0.05 and a minimum change in methylation of 0.05) across 15 genes and several intergenic regions. A classification model relying on these markers identified converters and nonconverters with an area under the receiver operating characteristic curve of 0.9644. CONCLUSION: This study shows that DNA methylation patterns at an early stage of psoriatic disease can distinguish between patients who will develop PsA from those who will not during the same follow-up.

Sex differences in the efficacy, safety and persistence of patients with psoriatic arthritis treated with tofacitinib: a post-hoc analysis of phase 3 trials and long-term extension.

BACKGROUND: Evaluate the impact of sex on tofacitinib efficacy, safety and persistence (time to discontinuation) in patients with psoriatic arthritis (PsA). METHODS: Data were pooled from two phase 3 randomised controlled trials. Patients were randomised to tofacitinib 5 mg or 10 mg two times per day, adalimumab 40 mg every 2 weeks or placebo. Efficacy outcomes to month 12 included American College of Rheumatology (ACR)20/50/70, minimal disease activity (MDA), Psoriasis Area Severity Index (PASI)75, change from baseline (∆) in Health Assessment Questionnaire-Disability Index (HAQ-DI) and ∆Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F). Safety was assessed to month 12 and persistence was assessed to month 42 of a long-term extension study. RESULTS: Overall, 816 patients were included (54.3% females). At baseline, higher tender joint counts, enthesitis scores and worse HAQ-DI and FACIT-F were reported in females versus males; presence of dactylitis and PASI were greater in males versus females. At month 3, tofacitinib efficacy generally exceeded placebo in both sexes. Overall, similar ACR20/50/70, PASI75, ∆HAQ-DI and ∆FACIT-F were observed for tofacitinib between sexes; females were less likely to achieve MDA. Similar proportions of males/females receiving tofacitinib (both doses) experienced treatment-emergent adverse events (AEs). Serious AEs occurred in 3.4%/6.6% and 4.0%/5.9% males/females with tofacitinib 5 mg and 10 mg two times per day. Persistence was generally similar between sexes. CONCLUSION: Tofacitinib efficacy exceeded placebo in both sexes and was comparable between sexes. Consistent with previous studies of PsA treatments, females were less likely to achieve MDA, likely due to baseline differences. Safety and time to discontinuation were generally similar between sexes. TRIAL REGISTRATION NUMBER: NCT01877668; NCT01882439; NCT01976364.

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.

Th17 gene expression in psoriatic arthritis synovial fluid and peripheral blood compared to osteoarthritis and cutaneous psoriasis.

OBJECTIVES: The IL-23/IL-17 axis is central to the pathogenesis of psoriatic arthritis (PsA). We aimed to identify Th17 signalling genes that are dysregulated in synovial fluid of PsA compared to osteoarthritis (OA) patients and to determine if differences in peripheral blood can distinguish PsA from psoriasis patients and controls. METHODS: Synovial fluid cells (SFCs) from 14 PsA and 9 OA patients were obtained and stored in TRIzol reagent. RNA was isolated by phenol-chloroform extraction and purified with RNeasy miniprep kits. Total RNA was extracted from PAXgene whole blood from 20 PsA, 20 psoriasis without arthritis (PsC) and 11 controls. Quantitative RT-PCR arrays were used to profile expression of 84 genes related to the Th17 regulatory network. Fold change differences were compared by Mann-Whitney U-test with false discovery rate (FDR) correction (FDR<0.05). RESULTS: In PsA compared to OA SFCs, a total of 33 genes were up-regulated and 27 genes were down-regulated. Signalling molecules (such as STAT3, FOXP3) were highly expressed in PsA SFCs, while cytokines (such as IL17F, IL6) were more predominant in OA SFCs after non-supervised hierarchal clustering. Nine genes (MMP3, CCL1, IL17C, CCL20, IL17F, IL3, CXCL5, IL6 and CX3CL1) had concordant expression in SFCs and in peripheral blood cells (PBCs) of PsA compared to PsC and/or controls. CONCLUSIONS: We identified expression differences in Th17 signalling genes in PsA compared to OA SFCs, with an elevation of signalling molecules and attenuation of cytokine expression in PsA. A subset of genes was concordant in PBCs; these may thus be potential biomarkers of PsA.

Epigenetics of psoriatic disease: A systematic review and critical appraisal.

Psoriasis is an inflammatory disease of the skin that is sometimes accompanied by an auto-inflammatory arthritis called psoriatic arthritis (PsA). Psoriasis and PsA are multifactorial diseases that result from complex interactions of environmental and genetic risk factors. Epigenetic marks, which are labile chemical marks with diverse functions, form a layer of biological information that sits at the interface of genetics and the environment. Aberrant epigenetic regulation has been previously implicated in other rheumatological disorders. The purpose of this review is to summarize and critically evaluate the nascent literature on epigenetics in psoriasis and PsA. A systematic review yielded 52 primary articles after applying inclusion and exclusion criteria. Data were extracted using a standardized template and study quality assessed using a methodological quality checklist. Studies reflect a broad range of epigenetic sub-disciplines, the most common being DNA methylation, followed by the parent of origin effect or genomic imprinting, expression or activity of epigenetic modifying enzymes, and histone modifications. Epidemiological studies demonstrating excessive paternal transmission provided the earliest evidence of epigenetic deregulation in psoriatic disease, however few studies have examined its molecular mechanisms. Methylation studies evolved rapidly from low resolution global to targeted analyses of known psoriatic disease susceptibility loci such as HLA-C*0602. The recent explosion of epigenome-wide association studies has provided us with novel insights into psoriasis pathogenesis, and the mechanism of action of UVB, methotrexate, and anti-TNF therapies, as well as molecular signatures of psoriasis that may have clinical relevance. Finally, recent studies of pharmacological inhibitors of epigenetic modifier enzymes demonstrate their potential applicability as novel treatment modalities for psoriasis. Challenges of epigenetics research in psoriasis and PsA were identified and future perspectives are discussed herein.

Differential gene and protein expression of chemokines and cytokines in synovial fluid of patients with arthritis.

BACKGROUND: Psoriatic arthritis (PsA), an inflammatory musculoskeletal disease, develops in approximately 30% of patients with psoriasis. Previously, chemokine (C-X-C motif) ligand 10 (CXCL10) was identified as a predictive biomarker of PsA in patients with psoriasis and was reduced after development of PsA. The purpose of the present study was to explore messenger RNA (mRNA) and protein expression of CXCL10 and its receptor, chemokine (C-X-C motif) receptor 3 (CXCR3), in the joints of patients with PsA to gain insight into their role in the pathogenesis of the disease. METHODS: Sera from 47 patients with PsA and 33 healthy control subjects were compared for expression of CXCL10 by Luminex assay. Synovial fluid (SF) was obtained from patients with PsA (n = 40), osteoarthritis (OA; n = 14), gout (n = 8), and rheumatoid arthritis (RA; n = 11) during clinical care. SF mRNA and protein expression of CXCL10, interleukin-17A (IL-17A), CXCR3, TBX21, RORC and/or interferon γ (IFNγ) were compared among the above-mentioned disease groups, as well as in paired SF and serum samples from patients with PsA using real-time polymerase chain reaction and Luminex assays, respectively. RESULTS: Serum CXCL10 was significantly higher in patients with PsA than in control subjects (p = 0.0007). CXCL10, IL-17A, and TBX21 expression were elevated in SF cells of patients with PsA compared with those of patients with OA and gout, but not those of patients with RA. CXCR3 and RORC were elevated in PsA SF cells compared with all other patient groups. Concordant results were obtained for CXCL10 and IL-17A protein expression. IFNγ was elevated in PsA SF compared with OA SF (p = 0.015). CXCL10 protein expression was substantially increased in SF (median 7283.9 pg/ml, interquartile range [IQR] 1330-10,362 pg/ml) compared with paired serum samples (median 282.06, IQR 180.7-395.8 pg/ml; p = 0.001), whereas IFNγ was significantly reduced (SF median 6.03 pg/ml, IQR 4.47-8.94 pg/ml; versus serum median 23.70 pg/ml, IQR 3.2-104.6 pg/ml; p = 0.001). CONCLUSIONS: CXCL10 may have an important etiological role in PsA that is analogous to that in RA, and it is a candidate biomarker to distinguish PsA from healthy individuals and from patients with OA and gout.

Brief Report: CXCL10 Is a Possible Biomarker for the Development of Psoriatic Arthritis Among Patients With Psoriasis.

OBJECTIVE: Biomarkers that can predict the development of psoriatic arthritis (PsA) in patients with psoriasis would be useful in clinical practice. The aim of this study was to assess whether CXCL10 could be a predictive biomarker of PsA prior to its onset. METHODS: Psoriasis patients without arthritis were followed up prospectively and assessed annually for development of PsA by a rheumatologist. Patients in whom PsA developed were designated as converters, while those in whom PsA did not develop were termed nonconverters. Baseline serum concentrations of CXCL10 were measured by Luminex assay in 46 converters and 45 nonconverters. RESULTS: The level of CXCL10 was significantly higher in converters (median 493 pg/ml [interquartile range (IQR) 356-984]) than in nonconverters (median 371 pg/ml [IQR 263-578]; P = 0.005). In contrast, C-reactive protein (CRP) levels were not significantly different between converters and nonconverters at baseline. CXCL10 was associated with conversion status after adjustment for age, sex, duration of psoriasis, and duration of follow-up (odds ratio 1.3, 95% confidence interval 1.1-1.5, P = 0.004). In a subset of converters, the CXCL10 level was significantly higher at baseline (median 927.4 pg/ml [IQR 547.6-1,243]) than after PsA diagnosis (491.5 pg/ml [IQR 323.2-607]; P < 0.0001), while CRP levels were lower at baseline (26.6 µg/ml [IQR 16.37-62.75]) than after PsA diagnosis (36.1 µg/ml [IQR 14.74-101.7]; P = 0.003). CXCL10 gene expression was increased 17.3-fold in synovial fluid (SF) compared with blood from PsA patients (P = 0.01) and 44.3-fold in the SF of PsA patients compared with the SF of patients with gout (P = 0.001). CONCLUSION: CXCL10 may be involved in PsA pathogenesis and is a candidate predictive biomarker for PsA in patients with psoriasis.

Further Evidence Supporting a Parent-of-Origin Effect in Psoriatic Disease.

OBJECTIVE: To further explore the "parent-of-origin" effect in a large cohort of well-phenotyped patients with cutaneous psoriasis without arthritis (PsC) and psoriatic arthritis (PsA). METHODS: Self-reported family history was obtained from PsA patients from Toronto and Newfoundland satisfying the Classification of Psoriatic Arthritis criteria, and PsC patients from Toronto, who were examined by a rheumatologist to exclude PsA. Proportions of probands with paternally and maternally transmitted psoriatic disease were compared by McNemar's and chi-square tests. Baseline clinical and genetic characteristics of probands with paternally and maternally transmitted disease were compared using logistic regression. RESULTS: A total of 849 probands reported a first-degree relative affected with psoriatic disease (PsC or PsA), of which 532 (63%) reported an affected parent. A significantly larger proportion of probands reported an affected father compared to an affected mother with psoriatic disease (289 [57%] versus 220 [43%], respectively; P = 0.003). This paternal transmission bias was evident in PsA (P = 0.006) and PsC probands, although it did not reach statistical significance in PsC probands (P = 0.20). Furthermore, the proportion of paternal PsC-proband PsA pairs (161 of 214 paternal transmissions [75%]) was significantly larger than maternal PsC-proband PsA pairs (103 of 161 maternal transmissions [64%]) (P = 0.02). Newfoundland probands with paternally transmitted disease had higher HLA-B*08 carriage (P = 0.04) and lower MICA-129Met carriage (P = 0.03). Males had higher HLA-B*38 carriage (P = 0.05) and a higher prevalence of nail lesions (P = 0.01). CONCLUSION: We have provided further epidemiologic evidence of a paternal transmission bias in psoriatic disease.

Killer-cell immunoglobulin-like receptor gene polymorphisms and susceptibility to psoriatic arthritis.

OBJECTIVES: We conducted a case-control study to determine the association between KIR2D and KIR3D gene polymorphisms and their interaction with HLA alleles in PsA. METHODS: A total of 678 subjects with PsA and 688 healthy controls were studied. Differences between cases and controls in the frequency of individual KIR polymorphisms were tested for significance by an asymptotic χ(2) test and Fisher's exact test. Trends for increasing susceptibility to PsA from combined genotypes (HLA-KIR and HLA) were evaluated by the Cochran-Armitage trend test. Multigene logistic regression analysis was conducted to identify independent associations and interactions. RESULTS: In univariate analyses, KIR2DL2 and KIR2DS2 polymorphisms were significantly associated with PsA. Only KIR2DS2 was associated with PsA compared with healthy controls in multivariate analysis [odds ratio (OR) 1.25, 95% CI 1.01, 1.54, P = 0.044]. The presence of HLA-C group 2 alleles was associated with a higher risk of PsA (trend test P = 0.006). The risk of PsA is higher when KIR2DS2 is present with the HLA-C ligands (C group 1) for the corresponding inhibitory KIRs, and is highest when KIR2DS2 is present in the absence of HLA-C ligands for homologous inhibitor KIRs, compared with the state when KIR2DS2 is absent (trend test P = 0.027). The presence of HLA-C alleles that have high cell surface expression was also associated with a higher risk of PsA (trend test P < 0.001). HLA-B Bw4 and HLA-B Bw4 80ile allele groups were associated with a higher PsA risk (trend test P < 0.0001 for both analyses). CONCLUSION: This study confirms the association of the KIR2DS gene, especially KIR2DS2, with PsA.

Soluble biomarkers associated with response to treatment with tumor necrosis factor inhibitors in psoriatic arthritis.

OBJECTIVE: To identify soluble biomarkers associated with response to therapy with tumor necrosis factor inhibitors (TNFi) in patients with psoriatic arthritis (PsA). METHODS: The study was conducted at a PsA clinic where patients are assessed every 6 months, and serum samples are collected and stored once a year at the time of clinical assessment. Forty patients with active PsA who gave serum samples prior to treatment with TNFi and after at least 3 months of therapy were identified. Patients were classified as TNFi responders if tender joint count was < 3, swollen joint count was 0, and Psoriasis Area and Severity Index score was < 4 at the time the second sample was collected. The following biomarkers were tested by ELISA: TNF superfamily 14, matrix metalloprotease-3 (MMP-3), receptor activator of nuclear factor kappa-B ligand, osteoprotegerin, cartilage oligomeric matrix protein (COMP), CPII, C2C and C1-2C, CS-846, and highly sensitive C-reactive protein. Paired t tests and logistic regression was used for statistical analyses. RESULTS: After a mean treatment duration of 11 months with TNFi (etanercept 28 patients, adalimumab 6, golimumab 4, infliximab 2), 29 patients were classified as TNFi responders. Baseline level of MMP-3 was independently associated with responder status (OR 1.067 for each 1-unit increase, p = 0.045). A reduction in MMP-3 levels with therapy increased the odds of achieving response (OR 1.213 for each 1-unit change, p = 0.030), whereas a reduction in COMP decreased the odds (OR 0.587, for each 100-unit increase, p = 0.039). None of the other biomarkers was associated with response. CONCLUSION: Baseline as well as reduction in serum MMP-3 and increase in serum COMP are independently associated with response to TNFi therapy in patients with PsA.

Genome-wide dissection of globally emergent multi-drug resistant serotype 19A Streptococcus pneumoniae.

BACKGROUND: Emergence of multi-drug resistant (MDR) serotype 19A Streptococcus pneumoniae (SPN) is well-documented but causal factors remain unclear. Canadian SPN isolates (1993-2008, n = 11,083) were serotyped and in vitro susceptibility tested. A subset of MDR 19A were multi-locus sequence typed (MLST) and representative isolates' whole genomes sequenced. RESULTS: MDR 19A increased in the post-PCV7 era while 19F, 6B, and 23F concurrently declined. MLST of MDR 19A (n = 97) revealed that sequence type (ST) 320 predominated. ST320 was unique amongst MDR 19A in that its minimum inhibitory concentration (MIC) values for penicillin, amoxicillin, ceftriaxone, and erythromycin were higher than for other ST present amongst post-PCV7 MDR 19A. DNA sequencing revealed that alleles at key drug resistance loci pbp2a, pbp2x, pbp2b, ermB, mefA/E, and tetM were conserved between pre-PCV7 ST 320 19F and post-PCV7 ST 320 19A most likely due to a capsule switch recombination event. A genome wide comparison of MDR 19A ST320 with MDR 19F ST320 identified 822 unique SNPs in 19A, 61 of which were present in antimicrobial resistance genes and 100 in virulence factors. CONCLUSIONS: Our results suggest a complex genetic picture where high-level drug resistance, vaccine selection pressure, and SPN mutational events have created a "perfect storm" for the emergence of MDR 19A.