Corinne Miceli-Richard

Genetics of rheumatoid arthritis contributes to biology and drug discovery

A major challenge in human genetics is to devise a systematic strategy to integrate disease-associated variants with diverse genomic and biological data sets to provide insight into disease pathogenesis and guide drug discovery for complex traits such as rheumatoid arthritis (RA). Here we performed a genome-wide association study meta-analysis in a total of >100,000 subjects of European and Asian ancestries (29,880 RA cases and 73,758 controls), by evaluating ∼10 million single-nucleotide polymorphisms. We discovered 42 novel RA risk loci at a genome-wide level of significance, bringing the total to 101 (refs 2, 3, 4). We devised an in silico pipeline using established bioinformatics methods based on functional annotation, cis-acting expression quantitative trait loci and pathway analyses—as well as novel methods based on genetic overlap with human primary immunodeficiency, haematological cancer somatic mutations and knockout mouse phenotypes—to identify 98 biological candidate genes at these 101 risk loci. We demonstrate that these genes are the targets of approved therapies for RA, and further suggest that drugs approved for other indications may be repurposed for the treatment of RA. Together, this comprehensive genetic study sheds light on fundamental genes, pathways and cell types that contribute to RA pathogenesis, and provides empirical evidence that the genetics of RA can provide important information for drug discovery.

Variants at multiple loci implicated in both innate and adaptive immune responses are associated with Sjögren’s syndrome

Sjögrens syndrome is a common autoimmune disease (affecting ∼0.7% of European Americans) that typically presents as keratoconjunctivitis sicca and xerostomia. Here we report results of a large-scale association study of Sjögrens syndrome. In addition to strong association within the human leukocyte antigen (HLA) region at 6p21 (Pmeta = 7.65 × 10−114), we establish associations with IRF5-TNPO3 (Pmeta = 2.73 × 10−19), STAT4 (Pmeta = 6.80 × 10−15), IL12A (Pmeta = 1.17 × 10−10), FAM167A-BLK (Pmeta = 4.97 × 10−10), DDX6-CXCR5 (Pmeta = 1.10 × 10−8) and TNIP1 (Pmeta = 3.30 × 10−8). We also observed suggestive associations (Pmeta < 5 × 10−5) with variants in 29 other regions, including TNFAIP3, PTTG1, PRDM1, DGKQ, FCGR2A, IRAK1BP1, ITSN2 and PHIP, among others. These results highlight the importance of genes that are involved in both innate and adaptive immunity in Sjögrens syndrome.

Expression of BAFF (BLyS) in T cells infiltrating labial salivary glands from patients with Sjögren's syndrome

Primary Sjögrens syndrome (pSS) is an autoimmune disorder characterized by lymphocytic infiltration of the salivary glands. Most of the infiltrating cells are T cells, but other features of the disease include polyclonal B‐cell activation, systemic production of autoantibodies, and increased risk of developing B‐cell non‐Hodgkins lymphoma. Recently, a new tumour necrosis factor, the B‐cell activating factor (BAFF; also known as BLyS), has been implicated in the polyclonal activation of B cells. Using immunohistochemistry, this study evaluated BAFF expression in labial salivary gland biopsies from 14 patients with pSS, 14 normal controls, and two patients with sarcoidosis. Labial salivary gland samples from seven patients with pSS, seven controls, and one patient with sarcoidosis were double‐stained using indirect immunofluorescence. RT‐PCR analysis was also performed on lip biopsy samples from two patients and two controls. In all 14 pSS specimens, infiltrating inflammatory cells strongly expressed BAFF protein, as did some ductal epithelial cells, but acinar cells were negative. Some B cells were present in the vicinity of the BAFF‐positive cells. In the 14 normal labial salivary glands, some ductal cells were moderately positive, but acinar cells were negative. In the labial salivary glands from the two patients with sarcoidosis, infiltrating lymphocytes were not stained. BAFF mRNA expression was confirmed by RT‐PCR in salivary glands from pSS patients. Double immunofluorescence revealed T cells and macrophages to be the main cell types expressing BAFF in salivary glands from pSS patients. In conclusion, BAFF may be expressed by T cells at the site of autoimmune damage and could play a role in the pathogenesis of pSS, particularly by triggering the activation of self‐antigen‐driven autoimmune B cells. Copyright

Increase of B cell-activating factor of the TNF family (BAFF) after rituximab treatment: insights into a new regulating system of BAFF production

Background: The cytokine B cell-activating factor of the TNF family (BAFF) is involved in the pathogenesis of autoimmune diseases. Objective: To access changes in serum protein and mRNA levels of BAFF after rituximab treatment. Methods: Serum and peripheral blood mononuclear cells (PBMCs) were isolated from five patients (two with lupus, two with Sjögren’s syndrome, one with rheumatoid arthritis) before and 12 weeks (range 7–17) after a first course of rituximab infusion. Monocytes and B cells were selected from healthy controls and cocultured for 72 h. BAFF protein and mRNA levels were assessed by ELISA and real-time PCR, respectively. Results: After rituximab treatment, median serum BAFF protein level and BAFF to actin mRNA ratio in PBMCs significantly increased. In monocytes cocultured with autologous B cells, BAFF protein level decreased, whereas the mRNA level was stable. In one closely monitored patient, the mRNA ratio of BAFF to actin in PBMCs increased later than the BAFF serum level. Conclusions: Two distinct mechanisms are probably involved in the increase in BAFF level after B cell depletion: (1) the decrease in its receptors leading to a release of BAFF; (2) a delayed regulation of BAFF mRNA transcription. This could favour the re-emergence of autoreactive B cells.

The familial form of spondylarthropathy: A clinical study of 115 multiplex families

OBJECTIVE To investigate the interrelationships among different phenotypes, and their relationship to the HLA-Blocus, in multiplex families with spondylarthropathy (SpA). METHODS We recruited 115 white French families, each of which had at least 2 members with SpA. Pedigrees were established. Clinical data and pelvic radiographs were collected. The HLA-B27 status of all patients was determined. Analysis was performed to determine the prevalence of SpA manifestations according to sex, disease duration, and HLA-B status, and to examine clustering of specific manifestations in subsets of families. RESULTS We identified 329 SpA patients. Mean +/-SD age at onset was 24+/-9.4 years. The male:female ratio was 186:143, or 1.3, with few sex differences in disease expression. Axial manifestations and HLA-B27 were each present in 97% of the patients. Inflammatory bowel disease and HLA-B35 were overrepresented in the 7 families containing HLA-B27-negative patients. The frequency of radiographic sacroiliitis increased in parallel with disease duration. Peripheral enthesitis, radiographic sacroiliitis, and psoriasis were evenly distributed in the families. Clustering independent of age was only observed for peripheral arthritis, suggesting that specific factors may predispose individuals to this manifestation. CONCLUSION Familial SpA appears to be homogeneous, based on the high frequencies of axial skeletal involvement and HLA-B27. The lack of clustering of most manifestations in families suggests that a predominant shared component, including HLA-B27, predisposes individuals to all forms of familial SpA, and that ubiquitous genetic or environmental factors contribute to phenotype diversity.

Symptomatic Efficacy of Etanercept and Its Effects on Objective Signs of Inflammation in Early Nonradiographic Axial Spondyloarthritis: A Multicenter, Randomized, Double‐Blind, Placebo‐Controlled Trial

To assess the efficacy of etanercept in the treatment of early active nonsteroidal antiinflammatory drug (NSAID)–refractory nonradiographic axial spondyloarthritis (SpA).

Viruses induce high expression of BAFF by salivary gland epithelial cells through TLR- and type-I IFN-dependent and -independent pathways.

B cell activating factor (BAFF) plays a key role in promoting B lymphocyte activation. We investigated whether danger signals induce BAFF secretion by cultured salivary gland epithelial cells (SGEC), which are the target of primary Sjögrens syndrome, a prototypic systemic autoimmune disease. SGEC cultures were established from minor salivary glands obtained from ten patients with pSS or sicca symptoms. BAFF mRNA and protein were measured after stimulation of the different Toll‐like receptors (TLR) by agonists or viruses. The expression of TLR2, –3, and –7 was detected in SGEC. Poly (I:C) (a synthetic TLR3 agonist) and reovirus‐1 (a dsRNA virus) induced high expression of BAFF mRNA (multiplied by a factor of 246 ± 39 (SEM) and 347 ± 66, respectively) and of BAFF protein secretion (58.49 ± 4.34 pg/mL and 69.73 ± 5.67). Inhibition of both the endosomal (by chloroquine) and IFN (by anti‐IFNAR antibody) pathways partly inhibited BAFF expression. Treatment with both dsRNA virus and poly (I:C) induced high levels of BAFF mRNA and protein expression by SGEC, through pathways dependent on and independent of TLR and dependent on and independent of IFN. BAFF induction by target organs of autoimmune diseases after viral infection may be a link between innate immunity and autoimmunity.

Integration of Sequence Data from a Consanguineous Family with Genetic Data from an Outbred Population Identifies PLB1 as a Candidate Rheumatoid Arthritis Risk Gene

Integrating genetic data from families with highly penetrant forms of disease together with genetic data from outbred populations represents a promising strategy to uncover the complete frequency spectrum of risk alleles for complex traits such as rheumatoid arthritis (RA). Here, we demonstrate that rare, low-frequency and common alleles at one gene locus, phospholipase B1 (PLB1), might contribute to risk of RA in a 4-generation consanguineous pedigree (Middle Eastern ancestry) and also in unrelated individuals from the general population (European ancestry). Through identity-by-descent (IBD) mapping and whole-exome sequencing, we identified a non-synonymous c.2263G>C (p.G755R) mutation at the PLB1 gene on 2q23, which significantly co-segregated with RA in family members with a dominant mode of inheritance (P = 0.009). We further evaluated PLB1 variants and risk of RA using a GWAS meta-analysis of 8,875 RA cases and 29,367 controls of European ancestry. We identified significant contributions of two independent non-coding variants near PLB1 with risk of RA (rs116018341 [MAF = 0.042] and rs116541814 [MAF = 0.021], combined P = 3.2×10−6). Finally, we performed deep exon sequencing of PLB1 in 1,088 RA cases and 1,088 controls (European ancestry), and identified suggestive dispersion of rare protein-coding variant frequencies between cases and controls (P = 0.049 for C-alpha test and P = 0.055 for SKAT). Together, these data suggest that PLB1 is a candidate risk gene for RA. Future studies to characterize the full spectrum of genetic risk in the PLB1 genetic locus are warranted.

The CGGGG insertion/deletion polymorphism of the IRF5 promoter is a strong risk factor for primary Sjögren's syndrome

OBJECTIVE Interferon regulatory factor 5 is a transcription factor involved in type I interferon (IFN) secretion. This study was undertaken to investigate whether a 5-bp (CGGGG insertion/deletion) promoter polymorphism is involved in genetic predisposition to primary Sjögrens syndrome (SS) and to assess the functional consequences of this polymorphism. METHODS The exploratory cohort consisted of 185 patients with primary SS and 157 healthy controls, and the replication cohort consisted of 200 patients with primary SS and 282 healthy controls. Levels of IRF5 messenger RNA (mRNA) were assessed at baseline and after in vitro infection with reovirus in peripheral blood mononuclear cells (PBMCs) from 30 patients with primary SS and from salivary gland epithelial cells that had been cultured for 4 weeks from patients with primary SS or sicca symptoms. RESULTS Carriage of the IRF5 4R CGGGG allele was associated with a greatly increased risk of primary SS in both cohorts (odds ratio 2.00 [95% confidence interval 1.5-2.7], P = 6.6 x 10(-6)). The CGGGG insertion/deletion polymorphism alone was sufficient to explain the association of primary SS with IRF5. The level of IRF5 mRNA in PBMCs depended significantly on genotype (P = 0.002) and was correlated with the levels of mRNA for the IFN-induced genes MX1 and IFITM1. Cultured salivary gland epithelial cells from patients carrying the 4R CGGGG IRF5 allele showed a high level of IRF5 mRNA (P = 0.04), which was amplified after reovirus infection (P = 0.026). CONCLUSION Our findings indicate an association of the CGGGG insertion/deletion polymorphism of the IRF5 promoter with primary SS. Patients carrying the 4R CGGGG IRF5 allele had a high level of mRNA for IRF5 in PBMCs and salivary gland epithelial cells, mainly after in vitro viral infection. Patients with high levels of mRNA for IRF5 also had high levels of mRNA for type I IFN-induced genes in PBMCs.

Markers of B-lymphocyte activation are elevated in patients with early rheumatoid arthritis and correlated with disease activity in the ESPOIR cohort.

IntroductionLittle is known about systemic B-cell activation in early rheumatoid arthritis (RA). We therefore evaluated the serum levels of markers of B-cell activation in patients included in the ESPOIR early arthritis cohort.MethodsIn the ESPOIR early arthritis cohort (at least 2 swollen joints for more than 6 weeks but less than 6 months), 710 patients were assessed at 1 year and either met the 1987 American College of Rheumatology criteria for RA (n = 578) or had undifferentiated arthritis (n = 132). Baseline serum samples of patients naïve to corticosteroid and disease-modifying antirheumatic drug treatment were assessed for beta2-microglobulin, IgG, IgA, IgM, immunoglobulin free light chains of immunoglobulins, and B-cell activating factor of the tumor necrosis factor family (BAFF). The BAFF gene 871T>C polymorphism was genotyped in all patients.ResultsAll markers of B-cell activation except BAFF and IgM were significantly higher in patients with early RA than those with undifferentiated arthritis. Anti-cyclic citrullinated peptide (anti-CCP) and beta2-microglobulin were associated with a diagnosis of early RA in the multivariate analysis. Markers of B-cell activation, except BAFF, were associated with disease activity, rheumatoid factor and anti-CCP secretion. The BAFF gene polymorphism was not associated with early RA.ConclusionsMarkers of B-cell activation are elevated in patients with early RA, compared with undifferentiated arthritis, independently of any systemic increase in BAFF secretion, and correlate with disease activity. This study sheds new light on the early pathogenic role of B-lymphocytes in RA and suggests that targeting them might be a useful therapeutic strategy in early RA.