Cytokines such as IL-12p70 (“IL-12”) and IL-23 can influence tumor progression. We tested the hypothesis that blood levels of IL-12p40, the common subunit of both cytokines, are associated with melanoma progression. Blood from 2,048 white melanoma patients were collected at a single institution between March 1998 and March 2011. Plasma levels of IL-12p40 were determined for 573 patients (discovery), 249 patients (validation 1), and 244 patients (validation 2). Per 10-unit change of IL-12p40 level was used to investigate associations with melanoma patient outcome among all patients or among patients with early or advanced stage. Among stage I/II melanoma patients in the pooled data set, after adjustment for sex, age, stage and blood draw time from diagnosis, elevated IL-12p40 was associated with melanoma recurrence (hazard ratio[HR]=1.04 per 10-unit increase in IL-12p40, 95% CI 1.02–1.06, P=8.48×10−5); Elevated IL-12p40 was also associated with a poorer melanoma specific survival (HR=1.06, 95% CI 1.03–1.09, P=3.35×10−5) and overall survival (HR=1.05, 95% CI 1.03–1.08, P=8.78×10−7) in multivariate analysis. Among stage III/IV melanoma patients in the pooled data set, no significant association was detected between elevated IL-12p40 and overall survival, or with melanoma specific survival, with or without adjustment for the above covariates. Early-stage melanoma patients with elevated IL-12p40 levels are more likely to develop disease recurrence and have a poorer survival. Further investigation with a larger sample size will be needed to determine the role of IL-12p40 in advanced stage melanoma patients.
cytokines; IL-12p40; melanoma; early-stage; progression
To determine human leukocyte antigen class I (HLA-class I) and II (HLA-class II) alleles associated with morphea (localized scleroderma) in the Morphea in Adults and Children (MAC) cohort by a nested case–control association study.
Morphea patients were included from MAC cohort and matched controls from the NIH/NIAMS Scleroderma Family Registry and DNA Repository and Division of Rheumatology at the University of Texas Health Science Center at Houston. HLA- Class II genotyping and SSCP typing was performed of HLA-A, -B, -C alleles. Associations between HLA-Class I and II alleles and morphea as well as its subphenotypes were determined.
There were 211 cases available for HLA-class I typing with 726 matched controls and 158 cases available for HLA Class-II typing with 1108 matched controls. The strongest associations were found with DRB1*04:04 (OR 2.3, 95% CI 1.4–4.0 P=0.002) and HLA-B*37 conferred the highest OR among Class I alleles (3.3, 95% CI 1.6–6.9, P= 0.0016). Comparison with risk alleles in systemic sclerosis determined using the same methods and control population revealed one common allele (DRB*04:04).
Results of the present study demonstrate specific HLA Class I and II alleles are associated with morphea and likely generalized and linear subtypes. The associated morphea alleles are different than in scleroderma, implicating morphea is also immunogenetically distinct. Risk alleles in morphea are also associated with conditions such as rheumatoid arthritis (RA) and other autoimmune conditions. Population based studies indicate patients with RA have increased risk of morphea, implicating a common susceptibility allele.
Systemic lupus erythematosus (SLE; OMIM 152700) is characterised by the production of antibodies to nuclear antigens. We previously identified variants in complement receptor 2 (CR2/CD21) that were associated with decreased risk of SLE. This study aimed to identify the causal variant for this association.
Genotyped and imputed genetic variants spanning CR2 were assessed for association with SLE in 15 750 case-control subjects from four ancestral groups. Allele-specific functional effects of associated variants were determined using quantitative real-time PCR, quantitative flow cytometry, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-PCR.
The strongest association signal was detected at rs1876453 in intron 1 of CR2 (pmeta=4.2×10−4, OR 0.85), specifically when subjects were stratified based on the presence of dsDNA autoantibodies (case-control pmeta=7.6×10−7, OR 0.71; case-only pmeta=1.9×10−4, OR 0.75). Although allele-specific effects on B cell CR2 mRNA or protein levels were not identified, levels of complement receptor 1 (CR1/CD35) mRNA and protein were significantly higher on B cells of subjects harbouring the minor allele (p=0.0248 and p=0.0006, respectively). The minor allele altered the formation of several DNA protein complexes by EMSA, including one containing CCCTC-binding factor (CTCF), an effect that was confirmed by ChIP-PCR.
These data suggest that rs1876453 in CR2 has long-range effects on gene regulation that decrease susceptibility to lupus. Since the minor allele at rs1876453 is preferentially associated with reduced risk of the highly specific dsDNA autoantibodies that are present in preclinical, active and severe lupus, understanding its mechanisms will have important therapeutic implications.
Systemic Lupus Erythematosus; Autoantibodies; Gene Polymorphism; B cells
Exploiting genotyping, DNA sequencing, imputation and trans-ancestral mapping, we used Bayesian and frequentist approaches to model the IRF5–TNPO3 locus association, now implicated in two immunotherapies and seven autoimmune diseases. Specifically, in systemic lupus erythematosus (SLE), we resolved separate associations in the IRF5 promoter (all ancestries) and with an extended European haplotype. We captured 3230 IRF5–TNPO3 high-quality, common variants across 5 ethnicities in 8395 SLE cases and 7367 controls. The genetic effect from the IRF5 promoter can be explained by any one of four variants in 5.7 kb (P-valuemeta = 6 × 10−49; OR = 1.38–1.97). The second genetic effect spanned an 85.5-kb, 24-variant haplotype that included the genes IRF5 and TNPO3 (P-valuesEU = 10−27–10−32, OR = 1.7–1.81). Many variants at the IRF5 locus with previously assigned biological function are not members of either final credible set of potential causal variants identified herein. In addition to the known biologically functional variants, we demonstrated that the risk allele of rs4728142, a variant in the promoter among the lowest frequentist probability and highest Bayesian posterior probability, was correlated with IRF5 expression and differentially binds the transcription factor ZBTB3. Our analytical strategy provides a novel framework for future studies aimed at dissecting etiological genetic effects. Finally, both SLE elements of the statistical model appear to operate in Sjögren's syndrome and systemic sclerosis whereas only the IRF5–TNPO3 gene-spanning haplotype is associated with primary biliary cirrhosis, demonstrating the nuance of similarity and difference in autoimmune disease risk mechanisms at IRF5–TNPO3.
To use high density genotyping to investigate the genetic associations of acute anterior uveitis (AAU) in patients both with and without ankylosing spondylitis (AS).
We genotyped 1,711 patients with AAU (either primary or with AAU and AS), 2,339 AS patients without AAU, and 10,000 controls on the Illumina Immunochip Infinium microarray. We also used data on AS patients from previous genomewide association studies to investigate the AS risk locus ANTXR2 for its putative effect in AAU. ANTXR2 expression in mouse eyes was investigated by RT-PCR.
Comparing all AAU cases with HC, strong association was seen over HLA-B corresponding to the HLA-B27 tag SNP rs116488202. Three non-MHC loci IL23R, the intergenic region 2p15 and ERAP1 were associated at genome-wide significance (P < 5×10−8). Five loci harboring the immune-related genes IL10-IL19, IL18R1-IL1R1, IL6R, the chromosome 1q32 locus harboring KIF21B, as well as the eye related gene EYS, were also associated at a suggestive level of significance (P < 5×10−6). A number of previously confirmed AS associations demonstrated significant differences in effect size between AS patients with AAU and AS patients without AAU. ANTXR2 expression was found to vary across eye compartments.
These findings, with both novel AAU specific associations, and associations shared with AS demonstrate overlapping but also distinct genetic susceptibility loci for AAU and AS. The associations in IL10 and IL18R1 are shared with inflammatory bowel disease, suggesting common etiologic pathways.
Anterior uveitis; uveitis; ankylosing spondylitis; HLA-B27; ANTXR2
Substantial advances have been made in the field of imaging in spondyloarthritis, with respect to both the techniques themselves and their applications, but how should clinicians and radiologists make the most of these developments? New recommendations from EULAR could provide valuable guidance.
The 40-year-old association of HLA-B27 with ankylosing spondylitis is one of the best examples of disease association with a hereditary marker. Genomewide association and family studies suggest that other important major histocompatibility complex (MHC) influences are operative in ankylosing spondylitis (AS) susceptibility. HLA-B27 positive hepatitis C individuals are immunologically more efficient in combating viral infections such as HIV-1, hepatitis C, and influenza and less efficient in combating against certain bacteria (and perhaps other organisms) capable of surviving intracellularly. A recent representative population survey of the frequency of HLA-B27 in the USA found a lower frequency of HLA-B27 in older US adults, perhaps reflecting this. Other HLA class I and class II alleles have been implicated in AS susceptibility, the most consistent being HLA-B*40/B60 (B*40:01) but also B14, B15, A*0201, DRB1*04:04, and certain DPA1 and DPB1 alleles. Non-HLA MHC alleles have also been implicated, although many such studies have been inconsistent, likely due to power issues related to the low number of HLA-B27-negative AS patients examined. The best evidence is for major histocompatibility complex class I chain-related gene A (MICA) whose recognition by intestinal epithelial T cells expressing different V-delta-1 gamma/delta TCR further implicates the gut in AS pathogenesis. The HLA class I and class II and other non-HLA allelic associations underscore the importance of T cells in AS pathogenesis.
Ankylosing spondylitis; Genetics; HLA genes; HLA-B27; Major histocompatibility complex; MIC-A; Spondylitis; Spondyloarthritis
With the growing awareness of the impact of chronic back pain and axial spondyloarthritis and recent breakthroughs in genetics and the development of novel treatments which may impact best on early disease, the need for markers that can facilitate early diagnosis and profiling those individuals at the highest risk for a bad outcome has never been greater. The genetic basis of ankylosing spondylitis has been considerably advanced, and HLA-B27 testing has a role in the diagnosis. Knowledge is still incomplete of the rest of the genetic contribution to disease susceptibility, and it is likely premature to use extensive genetic testing (other than HLA-B27) for diagnosis. Serum and plasma biomarkers have been examined extensively in assessing disease activity, treatment response, and as predictors or radiographic severity. For assessing disease activity, other than C-reactive protein and erythrocyte sedimentation rate, the most work has been in examining cytokines (particularly interleukin 17 and 23), matrix metalloproteinase (MMP) markers (particularly MMP3). For assessing those at the highest risk for radiographic progression, biomarkers of bony metabolism, cartilage and connective tissue degradation products, and adipokines have been most extensively assessed. The problem is that no individual biomarkers has been reproducibly shown to assess disease activity or predict outcome, and this area still remains an unmet need, of relevance to industry stakeholders, to regulatory bodies, to the healthcare system, to academic investigators, and finally to patients and providers.
Biomarkers; Diagnostic tools; Genetics; Radiographic outcome; Spondyloarthritis; Treatment response
Spondyloarthritis (SpA) represents a group of interrelated diseases with common clinical features and a close association with HLA-B27. Figures on the incidence and prevalence of diseases vary highly dependent on methodological differences between studies, the case definition used to classify disease and on the prevalence of HLA-B27 in the population studied. When summarizing the available literature, incidence rates of SpA are mainly based on the ESSG criteria and range between 0.48 and 63/100.000 while prevalence rates vary between 0.01 and 2.5%. For ankylosing spondylitis (AS), the most widely recognized representative of the SpA group of diseases, incidence rates of 0.44-7.3/100.000 and prevalence rates of 0.007-1.7% have been described in studies that were based on the (modified) New York criteria to classify cases. The incidence of psoriatic arthritis (PsA) varied from 3.6 up to 23.1/100.000 in different studies and prevalence between <0.1% and 0.4%, using a variety of classification criteria. The incidence of ReA has been estimated between 0.6 up to 28/100.000 in studies based on different source populations and different case definitions. The newly proposed criteria for axial SpA and peripheral SpA present an attractive new approach to facilitate classification of the SpA into two main subtypes and the axial SpA criteria allow earlier detection of patents with inflammatory back pain. It should be emphasized that these criteria were developed for use in a (specialized) clinical setting and not for large epidemiological studies.
Spondyloarthritis; Ankylosing Spondylitis; Psoriatic arthritis; Reactive arthritis; Epidemiology; Incidence; Prevalence
Human leucocyte antigen (HLA) B27 and HLA-B15 are associated with spondyloarthritis (SpA). Recent Assessment of SpondyloArthritis international Society (ASAS) criteria emphasise a distinction between SpA with axial and peripheral patterns. We analysed whether HLA-A, HLA-B and HLA-DRB1 alleles could associate with these patterns.
We studied 100 healthy individuals and 178 patients with SpA according to European Spondyloarthropathy Study Group (ESSG) criteria. Patients were then classified according to ASAS criteria, the axial spondyloarthritis pattern (axSpA) being defined by ascertained sacroiliitis and the peripheral pattern (pSpA) by enthesitis and/or arthritis in extremities. A combined ax/p pattern was also considered.
Only HLA-B27 and HLA-B15 alleles were associated with SpA. ASAS criteria for axSpA were met in 152 patients (12 with isolated axSpA and 140 with a combined ax/p patterns). When the ASAS peripheral criteria were applied, 161 patients met these criteria (13 with isolated pSpA and 148 with a combined ax/p pattern). HLA-B27 was found in 83% of patients with axSpA and 43% of ax/pSpA patients according to axASAS. HLA-B27 occurred in 7% controls but not in any patient with isolated pSpA. HLA-B15 was encountered in 31% of patients with isolated pSpA and 20% of ax/pSpA patients according to pASAS criteria. Moreover, 2 healthy controls, but none of our patients with isolated axSpA were positive for HLA-B15.
Our data suggest that the presence of HLA-B15 favours the development of isolated/combined peripheral rather than isolated axSpA, while HLA-B27 promotes an isolated/combined axial disease and excludes a peripheral pattern. HLA-B15 should be considered in addition to HLA-B27 when diagnosing patients with SpA according to ASAS criteria.
RHEUMATOLOGY; IMMUNOLOGY; GENETICS
The concept of inflammatory back pain (IBP) evolved in the 1970s, coincident with the discovery of the HLA-B27 association with ankylosing spondylitis (AS), leading to the development of criteria to determine the presence of IBP. The concept of IBP and it relationship with AS and axial spondyloarthritis (AxSpA) has further evolved, and an instrument developed (the Spondylitis Association of America Back Pain Tool), which was further modified and field tested for use in the 2009-2010 National Health and Nutrition Examination Survey (NHANES). This has shown the frequency of chronic back pain to have risen to 19.4%, with nearly one-third having IBP. The prevalence of AxSpA has been defined at 1.0-1.4% and AS at 0.52-0.55%. The national prevalence of HLA-B27 in the U.S. is 6.1%, and intriguing data from NHANES 2009 suggest a decreasing frequency with increasing age. From this arise new questions and a work agenda ahead.
Epidemiology; Spondyloarthritis; HLA-B27; Back Pain; Ankylosing Spondylitis
To carry out the first large-scale population study of the prevalence of HLA–B27 in the US, which is needed for public health planning purposes because of recent improvements in medical therapy and diagnostic testing for ankylosing spondylitis (AS).
The national prevalence of HLA–B27 was determined as part of the 2009 US National Health and Nutrition Examination Survey (NHANES), a cross-sectional survey monitoring the health and nutritional status of the US civilian, noninstitutionalized population. DNA polymerase chain reaction analysis was conducted in samples from 2,320 adults ages 20–69 years from this nationally representative sample.
The age-adjusted US prevalence of B27 was 6.1% (95% confidence interval [95% CI] 4.6–8.2). By race/ethnicity, the prevalence of B27 was 7.5% (95% CI 5.3–10.4) among non-Hispanic whites and 3.5% (95% CI 2.5–4.8) among all other US races/ethnicities combined. In Mexican Americans, the prevalence was 4.6% (95% CI 3.4–6.1). The prevalence of B27 could not be reliably estimated for other US racial/ethnic groups because of the low number of B27-positive individuals in those groups. For adults 50–69 years of age, the prevalence of B27 was 3.6% (95% CI 2.2–5.8), which suggested a decrease in B27 with age. These prevalence estimates took into account the NHANES survey design and are reviewed with respect to data from the medical literature.
Our findings provide the first US national prevalence estimates for HLA–B27. A decline in the prevalence of HLA–B27 with age is suggested by these data but must be confirmed by additional studies.
Although ankylosing spondylitis (AS) is driven by immunemediated processes, little is known about the presence and role of autoantibodies in this disease.
We performed human protein microarray analysis of sera derived from patients with AS and other autoimmune disorders to identify autoantibodies associated specifically with AS, and identified autoantibody targeting of protein phosphatase magnesium-dependent 1A (PPM1A) in AS. We performed ELISA analysis of sera from two independent AS cohorts to confirm autoantibody targeting of PPM1A, and to assess associations between levels of anti-PPM1A antibodies and AS disease severity or response (as measured by BASDAI score) to anti-TNF therapy. Levels of anti-PPM1A antibodies were also evaluated in sera from transgenic rats overexpressing HLA-B27 and human β2-microglobulin. The expression of PPM1A was assessed by immunohistochemistry in synovial tissues from patients with AS, rheumatoid arthritis, or osteoarthritis. The role of PPM1A on osteoblast differentiation was investigated by gene knock-down and overexpression.
AS was associated with autoantibody targeting of PPM1A, and levels of anti-PPM1A autoantibodies were significantly higher in patients with more advanced sacroiliitis and correlated with BASDAI score after treatment with anti-TNF agents. The levels of anti-PPM1A autoantibodies were also higher in sera of transgenic rats that are prone to develop AS than in those that are not. PPM1A was expressed in AS synovial tissue, and PPM1A overexpression promoted osteoblast differentiation, whereas PPM1A knockdown suppressed it.
Anti-PPM1A autoantibodies are present in AS, and our findings suggest that PPM1A may contribute to the pathogenic bone ankylosis characteristic of AS.
Recent investigation has identified association of IL-12p40 blood levels with melanoma recurrence and patient survival. No studies have investigated associations of single-nucleotide polymorphisms (SNPs) with melanoma patient IL-12p40 blood levels or their potential contributions to melanoma susceptibility or patient outcome. In the current study, 818,237 SNPs were available for 1,804 melanoma cases and 1,026 controls. IL-12p40 blood levels were assessed among 573 cases (discovery), 249 cases (case validation), and 299 controls (control validation). SNPs were evaluated for association with log[IL-12p40] levels in the discovery data set and replicated in two validation data sets, and significant SNPs were assessed for association with melanoma susceptibility and patient outcomes. The most significant SNP associated with log[IL-12p40] was in the IL-12B gene region (rs6897260, combined P=9.26 × 10−38); this single variant explained 13.1% of variability in log[IL-12p40]. The most significant SNP in EBF1 was rs6895454 (combined P=2.24 × 10−9). A marker in IL12B was associated with melanoma susceptibility (rs3213119, multivariate P=0.0499; OR=1.50, 95% CI 1.00–2.24), whereas a marker in EBF1 was associated with melanoma-specific survival in advanced-stage patients (rs10515789, multivariate P=0.02; HR=1.93, 95% CI 1.11–3.35). Both EBF1 and IL12B strongly regulate IL-12p40 blood levels, and IL-12p40 polymorphisms may contribute to melanoma susceptibility and influence patient outcome.
To report population based percentile reference values for selected spinal mobility measures in a nationally representative sample of 5103 U.S. adults ages 20–69 years examined in the 2009–10 U.S. National Health and Nutrition Examination Survey (NHANES).
Occiput-to-Wall Distance (OWD), Thoracic Expansion (TE), and Anterior Lumbar Flexion (ALF – modified Schober test) were measured by trained examiners in a standardized fashion. TE was measured at the xyphosternal level while the lower reference point for ALF was a line marked at the level of the superior margin of the lateral iliac crests. We report reference values based on the 95th percentile of OWD and 5th percentile of TE and ALF measurements, as well as other summary statistics for these measures in the study population.
An OWD of more than zero was present in 3.8 % of participants while 8.8% of participants had out of range values for TE based the commonly used threshold of 2.5 cm. The 95th percentile of OWD measurement was zero while the 5th percentile measurements for TE and ALF were 1.9 and 2 cm, respectively. The spinal measures were significantly associated with gender, age, ethnicity, height, and body mass index. Exclusion of individuals with severe obesity (BMI > 35) changed the proposed reference values for TE and ALF to 2.2 and 1.9 cm, respectively.
We verified the reference value of zero for OWD. Using the reported population based percentile values, new reference values for TE and the ALF can be derived.
Purpose of review
To review the optimal criteria and conditions for establishing a clinical registry, as well as detailing their application in a number of ankylosing spondylitis (AS) and axial spondyloarthritis (axSpA) Registries already in existence.
Recent genetic studies and studies of long-term treatment efficacy and side-effects have underscored the need for large numbers of patients, much larger than would be possible from a single center or consortium. An optimal Registry should have its aims established upfront, with appropriate governance and oversight, and inclusion and exclusion criteria for participating collaborators and subject defined. Collaborators contributing subjects to a Registry should use validated instruments for which they have been previously trained. The numerous cross-sectional and longitudinal Registries on AS and axSpA have been recently established that differ widely depending on the referral and selection issues.
The challenge of large-scale examinations of genetics, comorbidities, medication usage, and side-effects in spondyloarthritis underscores the need for combining data from well characterized registries of AS patients which require careful planning. There are currently many such registries available internationally, offering promise for collaborations and data pooling that can answer some of the pressing questions facing rheumatology clinicians and researchers.
genetics; patient cohorts; registries; spondyloarthritis; treatment outcome
Ankylosing spondylitis (AS) is a common, highly heritable, inflammatory arthritis for which HLA-B*27 is the major genetic risk factor, although its role in the aetiology of AS remains elusive. To better understand the genetic basis of the MHC susceptibility loci, we genotyped 7,264 MHC SNPs in 22,647 AS cases and controls of European descent. We impute SNPs, classical HLA alleles and amino acid residues within HLA proteins, and tested these for association to AS status. Here we show that in addition to effects due to HLA-B*27 alleles, several other HLA-B alleles also affect susceptibility. After controlling for the associated haplotypes in HLA-B we observe independent associations with variants in the HLA-A, HLA-DPB1 and HLA-DRB1 loci. We also demonstrate that the ERAP1 SNP rs30187 association is not restricted only to carriers of HLA-B*27 but also found in HLA-B*40:01 carriers independently of HLA-B*27 genotype.
Ankylosing spondylitis (AS)is associated with both significant direct and indirect costs,which vary by country, and have generally increased dramatically since the introduction of anti-TNF therapy. The cost-effectiveness of biologic agents is controversial, although cost-effectiveness studies need to consider the potential impact of anti-TNF treatments on work ability. Alternatives to reduce costs associated with biologics have been examined, including on-demand dosing and lower dose alternatives. Other treatment measures, such as total hip arthroplasty and physical therapy, are also effective in reducing pain and improving function in patients with AS, although the optimal type or combination of physical therapy treatment modalities, the optimal frequency and duration of treatment, and whether therapy is equally effective in stable disease and uncontrolled AS needs to be determined. No studies have examined differences in patient outcomes based on subspecialty care. Establishing an evidence base for these questions would help inform policy decisions to design the most cost-effective measures to treat AS.
Spondyloarthritis; Ankylosing Spondylitis; Psoriatic Arthritis; Economics; anti-TNF Treatment
Ankylosing spondylitis (AS) is a common, highly heritable, inflammatory arthritis for which HLA-B*27 is the major genetic risk factor, although its role in the aetiology of AS remains elusive. To better understand the genetic basis of the MHC susceptibility loci, we genotyped 7,264 MHC SNPs in 22,647 AS cases and controls of European descent. We impute SNPs, classical HLA alleles and amino-acid residues within HLA proteins, and tested these for association to AS status. Here we show that in addition to effects due to HLA-B*27 alleles, several other HLA-B alleles also affect susceptibility. After controlling for the associated haplotypes in HLA-B, we observe independent associations with variants in the HLA-A, HLA-DPB1 and HLA-DRB1 loci. We also demonstrate that the ERAP1 SNP rs30187 association is not restricted only to carriers of HLA-B*27 but also found in HLA-B*40:01 carriers independently of HLA-B*27 genotype.
Ankylosing spondylitis is a common, highly inheritable inflammatory arthritis with poorly understood biology. Here Brown, Cortes and colleagues use fine mapping of the major histocompatibility complex and identify novel associations, and identify other HLA alleles that like HLA-B27 interact with ERAP1 variants to influence disease risk.
To investigate whether the FcγRIIIa-66R/H/L polymorphism influences net effective receptor function and to assess if the FCGR3A combined genotypes formed by FcγRIIIa-66R/H/L and FcγRIIIa-176F/V as well as copy number variation (CNV) confer risk for development of SLE and lupus nephritis.
FcγRIIIa variants, expressed on A20 IIA1.6 cells, were used in flow cytometry-based human IgG binding assays. FCGR3A SNP and CNV genotypes were determined by Pyrosequencing methodology in a cohort of 1728 SLE patients and 2404 healthy controls.
The FcγRIIIa-66L/H/R (rs10127939) polymorphism influences ligand binding capacity in the context of the FcγRIIIa-176V (rs396991) allele. The low binding FcγRIIIa-176F allele was associated with SLE nephritis (p = 0.0609) in African Americans but not in European Americans (p > 0.10). Nephritis among African American SLE subjects was associated with FcγRIIIa low binding haplotypes containing the 66R/H/L and 176F variants (p = 0.03) and with low binding genotype combinations (p = 0.002). No association was observed in European American SLE patients. The distribution of FCGR3A CNV was not significantly different between controls and SLE patients with or without nephritis.
FcγRIIIa-66R/H/L influences ligand binding. The low binding haplotypes formed by 66R/H/L and 176F confer enhanced risk for lupus nephritis in African Americans. FCGR3A CNVs are not associated with SLE or SLE nephritis in either African Americans or European Americans.
Many challenges have made it difficult to determine the prevalence of spondyloarthritis (SpA) in North America. They include the ethnic heterogeneity of the population, the lack of feasibility of applying current criteria (such as requirements for HLA-B27 testing and imaging studies such are pelvic radiographs and MRI scanning) and the transient nature of some SpA symptoms (ie, peripheral arthritis, enthesitis). Current estimates of the prevalence of SpA in the United States range between 0.2% and 0.5% for ankylosing spondylitis, 0.1% for psoriatic arthritis, 0.065% for enteropathic peripheral arthritis, between 0.05% and 0.25% for enteropathic axial arthritis, and an overall prevalence of SpA as high as over one percent. With newer population-based instruments becoming available, the availability of the widely validated European Spondyloarthropathy Study Group (ESSG) criteria and the lower cost and greater feasibility of genetic testing, opportunities for true population-based studies of SpA are possible and will likely soon ensue.
Epidemiology; ankylosing spondylitis; psoriatic arthritis; enteropathic arthritis; spondyloarthritis
Genome wide association studies have identified variants in PXK that confer risk for humoral autoimmune diseases, including systemic lupus erythematosus (SLE or lupus), rheumatoid arthritis and more recently systemic sclerosis. While PXK is involved in trafficking of epidermal growth factor Receptor (EGFR) in COS-7 cells, mechanisms linking PXK to lupus pathophysiology have remained undefined. In an effort to uncover the mechanism at this locus that increases lupus-risk, we undertook a fine-mapping analysis in a large multi-ancestral study of lupus patients and controls. We define a large (257kb) common haplotype marking a single causal variant that confers lupus risk detected only in European ancestral populations and spans the promoter through the 3′ UTR of PXK. The strongest association was found at rs6445972 with P < 4.62 × 10−10, OR 0.81 (0.75–0.86). Using stepwise logistic regression analysis, we demonstrate that one signal drives the genetic association in the region. Bayesian analysis confirms our results, identifying a 95% credible set consisting of 172 variants spanning 202 kb. Functionally, we found that PXK operates on the B-cell antigen receptor (BCR); we confirmed that PXK influenced the rate of BCR internalization. Furthermore, we demonstrate that individuals carrying the risk haplotype exhibited a decreased rate of BCR internalization, a process known to impact B cell survival and cell fate. Taken together, these data define a new candidate mechanism for the genetic association of variants around PXK with lupus risk and highlight the regulation of intracellular trafficking as a genetically regulated pathway mediating human autoimmunity.
lupus; PXK; fine-mapping; B cells; BCR
Thrombosis is a serious complication of systemic lupus erythematosus (SLE). Studies that have
investigated the genetics of thrombosis in SLE are limited. We undertook this study to assess the
association of previously implicated candidate genes, particularly Toll-like receptor (TLR) genes,
with pathogenesis of thrombosis.
We genotyped 3,587 SLE patients from 3 multiethnic populations for 77 single-nucleotide
polymorphisms (SNPs) in 10 genes, primarily in TLRs 2, 4, 7, and 9, and we also genotyped 64
ancestry-informative markers (AIMs). We first analyzed association with arterial and venous
thrombosis in the combined population via logistic regression, adjusting for top principal
components of the AIMs and other covariates. We also subjected an associated SNP, rs893629, to
meta-analysis (after stratification by ethnicity and study population) to confirm the association
and to test for study population or ethnicity effects.
In the combined analysis, the SNP rs893629 in the KIAA0922/TLR2 region was
significantly associated with arterial thrombosis (logistic P = 6.4 ×
10−5, false discovery rate P = 0.0044). Two additional SNPs in
TLR2 were also suggestive: rs1816702 (logistic P = 0.002) and
rs4235232 (logistic P = 0.009). In the meta-analysis by study population, the odds
ratio (OR) for arterial thrombosis with rs893629 was 2.44 (95% confidence interval
1.58–3.76), without evidence for heterogeneity (P = 0.78). By ethnicity, the
effect was most significant among African Americans (OR 2.42, P = 3.5 ×
10−4) and European Americans (OR 3.47, P = 0.024).
TLR2 gene variation is associated with thrombosis in SLE, particularly among
African Americans and European Americans. There was no evidence of association among Hispanics, and
results in Asian Americans were limited due to insufficient sample size. These results may help
elucidate the pathogenesis of this important clinical manifestation.
To examine the prevalence of isolated IgA anti-β2Glycoprotein I (anti-β2GPI) positivity and the association of these antibodies, and a subgroup that bind specifically to domain IV/V of β2GPI, with clinical manifestations of the Antiphospholipid Syndrome (APS) in three patients groups. The pathogenicity of IgA anti-β2GPI was also evaluated in a mouse model of thrombosis.
Patients with systemic lupus erythematosus (SLE) from a multiethnic, multicenter cohort (LUpus in MInorities, NAture versus nurture [LUMINA]) (n=558), patients with SLE from the Hopkins Lupus Cohort (n=215), and serum samples referred to the Antiphospholipid Standardization Laboratory (APLS) (n=5,098) were evaluated. IgA anti-β2GPI titers and binding to domain IV/V of β2GPI were examined by enzyme-linked immunosorbent assay (ELISA). CD1 mice were inoculated with purified IgA anti- β2GPI antibodies, and surgical procedures and ELISAs were performed to evaluate thrombus development and tissue factor (TF) activity.
A total of 198 patients were found to be positive for IgA anti-β2GPI isotype, and 57 patients were positive exclusively for IgA anti-β2GPI antibodies. Of these, 13 of 23 patients (56.5%) in the LUMINA cohort, 17 of 17 patients (100%) in the Hopkins cohort, and 10 of 17 patients (58.9%) referred to APLS had at least one APS-related clinical manifestation. Fifty-four percent of all the IgA anti-β2GPI positive serum samples reacted with domain IV/V of anti-β2GPI, and 77% of those had clinical features of APS. Isolated IgA anti-β2GPI positivity was associated with an increased risk for arterial thrombosis (p<0.001), venous thrombosis (p=0.015) and all thrombosis (p<0.001). The association between isolated IgA anti-β2GPI and arterial thrombosis (p=0.0003) and all thrombosis (p=0.0003) remained significant after adjusting for other risk factors for thrombosis. In vivo mouse studies demonstrated that IgA anti-β2GPI antibodies induced significantly larger thrombi and higher TF levels compared to controls.
Isolated IgA anti-β2GPI positive titers may identify additional patients with clinical features of APS. Testing for these antibodies when other antiphospholipid (aPL) tests are negative and APS is suspected is recommended. IgA anti-β2GPI antibodies directed to domain IV/V of β2GPI represent an important subgroup of clinically relevant antiphospholipids.