Fawnda Pellett

CARD15: a Pleiotropic Autoimmune Gene That Confers Susceptibility to Psoriatic Arthritis

A recent genomewide scan in psoriatic arthritis (PsA) revealed a susceptibility locus at 16q. This region overlaps CARD15, a susceptibility gene in Crohn disease. The possibility of a common susceptibility gene between PsA and Crohn disease is further supported by epidemiological studies that note an increased incidence of psoriasis in subjects with Crohn. We screened 187 patients with PsA and 136 healthy controls, all from Newfoundland, for the three common, independent sequence variants of CARD15 (R702W, leu1007fsinsC, and G908R), which were detected by polymerase chain reaction by use of allele-specific primers and visualized through gel electrophoresis. In total, 53/187 (28.3%) probands with PsA had at least one variant of the CARD15 gene, compared with 16/136 (11.8%) controls (odds ratio 2.97; 95% confidence interval 1.61-5.47; P=.0005). Allele frequencies of R702W, leu1007fsinsC, and G908R were 10.43%, 3.21%, and 1.61%, respectively, in patients with PsA, compared with 3.31%, 2.57%, and 0.37%, respectively, in the control patients. CARD15 conferred susceptibility to PsA independent of HLA-Cw*0602. Thus, CARD15 represents a pleiotropic autoimmune gene and is the first non-MHC gene to be associated with PsA.

Soluble biomarkers differentiate patients with psoriatic arthritis from those with psoriasis without arthritis

OBJECTIVEnBiomarkers may be helpful in screening patients with psoriasis for PsA. Our purpose was to identify serum biomarkers for psoriasis and PsA.nnnMETHODSnFifty-two patients with psoriasis (26 satisfying CASPAR classification criteria for PsA) and 26 healthy controls were recruited for our study. Patients with psoriasis and PsA were group matched for age, sex and psoriasis duration, whereas controls were matched for age and sex. Blood samples were drawn at the time of assessment and serum was analysed for the following: IL-12, IL-12p40, IL-17, TNF super family member 14 (TNFSF14), MMP-3, RANK ligand (RANKL), osteoprotegerin (OPG), cartilage oligomeric matrix protein (COMP), C-propeptide of Type II collagen (CPII), collagen fragment neoepitopes Col2-3/4(long mono) (C2C) and Col2-3/4(short) (C1-2C) and highly sensitive CRP (hsCRP). Data were analysed using logistic regression and receiver operating characteristic curves were plotted.nnnRESULTSnFifty-two patients with psoriatic disease had a mean age of 46 years and psoriasis duration of 16.8 years. Compared with controls, increased serum levels of RANKL, TNFSF14, MMP-3 and COMP independently associated with psoriatic disease (P < 0.05). Twenty-six PsA patients (mean swollen and/or tender joint count 16, swollen joint count 5) were then compared with 26 patients who had psoriasis alone. Increased levels of hsCRP, OPG, MMP-3 and the CPII : C2C ratio were independently associated with PsA (P < 0.03).nnnCONCLUSIONnThis pilot study indicates that hsCRP, OPG, MMP-3 and the CPII : C2C ratio are biomarkers for PsA in patients with psoriasis.

Mechanisms of copy number variation and hybrid gene formation in the KIR immune gene complex

The fine-scale structure of the majority of copy number variation (CNV) regions remains unknown. The killer immunoglobulin receptor (KIR) gene complex exhibits significant CNV. The evolutionary plasticity of the KIRs and their broad biomedical relevance makes it important to understand how these immune receptors evolve. In this paper, we describe haplotype re-arrangement creating novel loci at the KIR complex. We completely sequenced, after fosmid cloning, two rare contracted haplotypes. Evidence of frequent hybrid KIR genes in samples from many populations suggested that re-arrangements may be frequent and selectively advantageous. We propose mechanisms for formation of novel hybrid KIR genes, facilitated by protrusive non-B DNA structures at transposon recombination sites. The heightened propensity to generate novel hybrid KIR receptors may provide a proactive evolutionary measure, to militate against pathogen evasion or subversion. We propose that CNV in KIR is an evolutionary strategy, which KIR typing for disease association must take into account.

TNFα polymorphisms and risk of psoriatic arthritis

Background: Tumour necrosis factor α (TNFα) is a cytokine of critical importance in psoriatic arthritis. Objectives: (1) To examine the association between TNFα promoter gene polymorphisms and psoriatic arthritis in two well characterised Canadian populations with the disease; (2) to carry out a meta-analysis of all TNFα association studies in white psoriatic arthritis populations. Methods: DNA samples were genotyped for five TNF variants by time of flight mass spectrometry using the Sequenom platform. All five single nucleotide polymorphisms were in the 5′ flanking region of TNFα gene at the following positions: −1031 (T→C), −863 (C→A), −857 (C→T), −308 (G→A), and −238 (G→A). Primary analyses were based on logistic regression. Summary estimates of disease/genotype relations from several studies were derived from random effects meta-analyses. Results: 237 psoriatic arthritis subjects and 103 controls from Newfoundland and 203 psoriatic arthritis subjects and 101 controls from Toronto were studied. A combined analysis of data from both populations, showed a significant association between disease status and the −238(A) variant (pu200a=u200a0.01). The meta-analysis estimate for the −238(A) TNFα variant in eight psoriatic arthritis populations was also significant (odds ratiou200a=u200a2.29 (95% confidence interval, 1.48 to 3.55)). Conclusions: Analysis of TNFα variants in psoriatic arthritis populations shows that the −238 (A) variant is a significant risk factor for this disease.

Folate Pathway Enzyme Gene Polymorphisms and the Efficacy and Toxicity of Methotrexate in Psoriatic Arthritis

Objective. To determine the association between folate pathway gene polymorphisms and the effectiveness, toxicity, and drug survival of methotrexate (MTX) in psoriatic arthritis (PsA). Methods. Data were obtained from a longitudinal cohort of PsA patients evaluated according to a standard protocol. Data on duration of drug therapy, dose, side effects, and reasons for discontinuation are systematically recorded. Patients treated with MTX after clinic admission who had ≥ 3 swollen joints prior to initiating MTX therapy were selected for evaluation of effectiveness. Response to MTX treatment was assessed at 6 months. Data from all patients treated in the clinic with MTX were used in evaluation of toxicity and drug survival. The following single-nucleotide polymorphisms (SNP) were measured using the Sequenom platform: MTHFR 677C>T (rs1801133), MTHFR 1298A>C (rs1801131), DHFR −473T>C (rs1650697), DHFR 35289A>G (rs1232027), and RFC 80G>A (rs1051266). Fisher’s exact test, logistic regression, and Cox proportional hazard analyses were used to determine association. Results. Two hundred eighty-one patients were identified from the database. All patients were included in the analysis for side effects and drug survival, and 119 patients were included in the effectiveness analysis. The minor A allele of DHFR gene at +35289 was the only SNP demonstrating association with response to MTX therapy (OR 2.99, p = 0.02). Patients homozygous for the minor allele of MTHFR 677C/T (677TT) had more liver toxicity (Fisher exact test, p = 0.04). Conclusion. Polymorphisms of the DHFR gene may be associated with MTX efficacy. MTHFR 677TT may have a relationship with MTX-induced liver toxicity in 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.

Differential human leucocyte allele association between psoriasis and psoriatic arthritis: a family-based association study

Objective A recent population-based study identified several HLA alleles as conferring a risk for psoriatic arthritis (PsA) among patients with psoriasis. The authors aimed to confirm these results using a family-based association study. Methods PsA probands, psoriasis probands and their first-degree family members were included. All participants were evaluated for the presence of psoriasis and inflammatory arthritis. HLA-B and -C genotyping was performed. The family-based association test was used to test for differences between PsA and psoriasis patients in transmission of candidate alleles from parents to offspring. Results A total of 178 PsA and 30 psoriasis probands and 561 first degree family members were analysed. The following HLA alleles were over-transmitted to PsA compared with psoriasis: HLA-C*12 (p=0.005), HLA-B*38 (p=0.04), HLA-B*39 (p=0.03), HLA-B*27 (p=0.002). Conclusions HLA-B*27, HLA-B*38, HLA-B*39 and HLA-C*12 alleles are potential PsA-specific genetic markers among patients with psoriasis.

Serum kallikrein-8 correlates with skin activity, but not psoriatic arthritis, in patients with psoriatic disease

Abstract Background: About 30% of cutaneous psoriasis (PsC) patients develop psoriatic arthritis (PsA) in the joint, which is under-recognized by dermatologists. Biomarkers for PsA are needed so that early referral to a rheumatologist is made. Kallikreins (KLKs) are secreted serine proteases implicated in skin desquamation and inflammation. This study examined KLK potential as serum biomarkers of PsA in cutaneous psoriasis patients. Methods: KLKs were measured by ELISAs in synovial fluids of three PsA patients and three control early osteoarthritis (OA) patients, as well as in a cohort of 152 serum samples collected from age- and sex-matched PsC patients, with (n=76) or without PsA (n=76). KLK expression in psoriatic plaques was examined by immunohistochemistry. Univariate and multivariate logistic regression analyses were conducted to analyze the association between serum KLK levels and disease class (PsC, PsA). Serum KLKs that associated with PsA were correlated with clinical parameters of skin and joint activity. Results: Among the seven KLKs tested, KLK6 and KLK8 were elevated in both PsA synovial fluids and psoriatic plaques, but only serum KLK8 levels were associated with psoriatic disease (odds ratio=2.56, p=0.03). Although significantly elevated in PsC and PsA sera compared to healthy controls, KLK8 did not discriminate PsA from PsC patients. KLK8 correlated positively with the psoriasis area and severity index (PASI) (r=0.43, p=0.001) independent of age, sex and psoriasis duration (β=1.153, p=0.0003) and exhibited no correlations with tender or swollen joint counts. Conclusions: Increased KLK8 serum level in PsA patients reflects disease activity in the skin but not in the joints. Serum KLK levels are not useful for screening psoriasis patients for PsA.

Clinical and Demographic Characteristics of Erosion-free and Erosion-present Status in Psoriatic Arthritis in a Cohort Study

Objective. Psoriatic arthritis (PsA) has been recognized as a severe erosive disease. However, some patients do not develop erosions. We aimed to determine the prevalence, characteristics, and predictors of erosion-free patients (EFP) as compared with erosion-present patients (EPP) among patients with PsA followed prospectively. Methods. This is a retrospective analysis conducted on patients from the Toronto PsA cohort. Patients with at least 10 years of followup and radiographs were analyzed. Radiographs were scored with the modified Steinbrocker method. Baseline (first visit to clinic) characteristics were used to predict the development of erosions with logistic regression models. To examine the effect of time-varying covariates, Cox regression models were fit for the time to development of erosions from baseline. Results. Among 290 patients, 12.4% were EFP and 87.6% were EPP over the study period. The mean time to development of erosion in the EPP over the course of followup was 6.8 ± 6.1 years. EFP were diagnosed with psoriasis at a younger age compared with EPP. In both models, actively inflamed joints and clinically damaged joints were predictive of the development of erosion, whereas a longer duration of psoriasis at baseline decreased the odds of developing erosion. EPP had a higher percentage of unemployment as compared with EFP at baseline and followup visits. Conclusion. Among patients with PsA followed for at least 10 years, 12.4% never develop erosions. The clinical and radiographic findings can ultimately assist in the stratification of a patient’s prognosis regarding the development of erosions.

Immunoglobulin G Subclass Analysis in Psoriatic Arthritis

Objective. The occurrence of monoclonal gammopathy of undetermined significance (MGUS) is common in chronic immune mediated disorders. This increased monoclonal antibody production could result from chronic stimulation of lymphocytes, with the immunoglobulin G (IgG) subtype accounting for the majority of cases in psoriatic arthritis (PsA). We aimed to identify IgG subclass profiles in patients with PsA and to determine association with specific disease characteristics. Methods. Serum samples from 221 patients with PsA from a single cohort were analyzed for their serum IgG subclass levels. All patients fulfilled the ClASsification for Psoriatic ARthritis (CASPAR) criteria and were followed at 6-month to 12-month intervals according to a standard protocol. MGUS was defined as the occurrence of a discrete band in the gammaglobulin region on at least 2 separate serum protein electrophoresis tests performed 6 months apart. Patients with high abnormal IgG subclass levels were compared to patients with normal levels using descriptive tests. Results. Elevations of IgG1-4 were common in PsA, with ∼20%–49% of patients having elevations of each subclass, IgG2 being the most common subclass abnormality. However, no clinical-serological correlation was found in the group with abnormal IgG2 levels. Of the 38 patients with MGUS, elevations in IgG1 were most common. Patients with an abnormal IgG1 subclass level were more likely to have a discrete band in the gammaglobulin region, higher prevalence of MGUS, and abnormal erythrocyte sedimentation rate or C-reactive protein levels. Conclusion. Determination of the IgG subclass concentration in PsA did not seem to add any significant value in identifying specific disease manifestations. However, this study provides insight into the pathological process leading to MGUS in PsA.