Anti-cyclic citrullinated peptide antibody is associated with radiographic erosion in rheumatoid arthritis independently of shared epitope status

Increased expression of CXCL2 in ACPA-positive rheumatoid arthritis and its role in osteoclastogenesis

Anti-citrullinated protein/peptide antibodies (ACPA) play important roles in the pathogenesis of rheumatoid arthritis (RA). ACPA-positive (ACPA⁺ ) and ACPA-negative (ACPA^- ) RA were suggested to be different disease subsets, with distinct differences in genetic variation and clinical outcomes. The aims of the present study were to compare gene expression profiles in ACPA⁺ and ACPA^- RA, and to identify novel candidate gene signatures that might serve as therapeutic targets. Comprehensive transcriptome analysis of peripheral blood mononuclear cells (PBMCs) from ACPA⁺ and ACPA^- RA patients and healthy controls was performed via RNA sequencing. A validation cohort was used to further investigate differentially expressed genes via polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Spearman's correlation test was used to evaluate the correlation of differentially expressed genes and the clinical and laboratory data of the patients. The role of differentially expressed genes in osteoclastogenesis was further investigated. Expression of C-X-C motif chemokine ligand 2 (CXCL2) was significantly increased in ACPA⁺ RA than in ACPA^- RA, which was validated in PBMCs and serum. CXCL2 promoted the migration of CD14⁺ monocytes and increased osteoclastogenesis in RA patients. RAW264.7 macrophages were used to investigate specific mechanisms, and the results suggested that CXCL2 stimulated osteoclastogenesis via extracellular receptor kinase (ERK) mitogen-activated protein kinase (MAPK) and nuclear factor kappa B pathways. In conclusion, CXCL2 was highly expressed in ACPA⁺ RA than in ACPA^- RA. CXCL2 promoted osteoclastogenesis and was related to bone erosion in RA, which suggests that the blockade of CXCL2 might be a novel strategy for the treatment of RA.

Efficacy and safety of sarilumab in combination with csDMARDs or as monotherapy in subpopulations of patients with moderately to severely active rheumatoid arthritis in three phase III randomized, controlled studies

Background

The interleukin-6 receptor inhibitor sarilumab demonstrated efficacy in combination with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or as monotherapy in patients with moderately to severely active rheumatoid arthritis (RA) with an inadequate response (IR) or intolerant (INT) to methotrexate (MTX) or tumour necrosis factor (TNF)-α inhibitors. This analysis investigated the efficacy and safety of sarilumab in patient subgroups.

Methods

Data were included from phase III studies: two placebo-controlled studies of subcutaneous sarilumab 150/200 mg every 2 weeks (q2w) either + MTX in MTX-IR patients (52 weeks) or + csDMARDs in TNF-IR/INT patients (24 weeks), and a monotherapy study of sarilumab 200 mg q2w vs. adalimumab 40 mg q2w in MTX-IR/INT patients (24 weeks). Prespecified and post hoc subgroups included patient demographics, disease characteristics, and prior treatments. Prespecified and post hoc endpoints included clinical, radiographic, and physical function measures, and p values are considered nominal. Safety was assessed during double-blind treatment.

Results

The superiority of sarilumab (either as monotherapy vs. adalimumab or in combination with csDMARDs vs. placebo + csDMARDs) across clinical endpoints was generally consistent across subgroups defined by patient demographics, disease characteristics, and prior treatments, demonstrating the benefit of sarilumab treatment for a wide range of patient types. Interaction p values of < 0.05 were consistently observed across studies only for baseline anti-cyclic citrullinated peptide antibody (ACPA) status for American College of Rheumatology 20% response, but not American College of Rheumatology 50% or 70% response. Adverse events and worsening laboratory parameters occurred more frequently in sarilumab-treated vs. placebo-treated patients and were more frequent in the small number of patients ≥ 65 years (n = 289) vs. patients < 65 years (n = 1819). Serious infections occurred in six patients aged ≥ 65 years receiving sarilumab, although the incidence of serious infections was generally higher in patients aged ≥ 65 years regardless of treatment.

Conclusions

Apart from ACPA status, there were no consistent signals indicating differential effects of sarilumab in any of the subpopulations assessed. Sarilumab demonstrated consistent efficacy and safety across a wide range of patients with RA.

Trial registration

ClinicalTrials.gov NCT01061736, registered on February 03, 2010; ClinicalTrials.gov NCT01709578, registered on October 18, 2012; ClinicalTrials.gov NCT02332590, registered on January 07, 2015

Periodontitis is associated with rheumatoid arthritis: a study with longstanding rheumatoid arthritis patients in Korea

BACKGROUND/AIMS

A cross-sectional study was undertaken to investigate the association between severity of periodontitis and clinical manifestation of rheumatoid arthritis (RA).

METHODS

Two hundred sixty-four RA patients and 88 age- and sex-matched controls underwent dental exam. Additionally, clinical manifestations including disease activity and anti-citrullinated protein antibodies were evaluated in RA patients.

RESULTS

The prevalence of moderate or severe periodontitis was higher in RA patients compared to controls (63.6% vs 34.1%, p < 0.001). In markers of periodontal inflammation, bleeding on probing was correlated with disease activity score 28 (r = 0.128, p = 0.041), RA disease duration (r = 0.211, p = 0.001), erythrocyte sedimentation rate (ESR; r = 0.141, p = 0.023), anti-cyclic citrullinated peptide antibody (r = 0.183, p = 0.009), and anti-citrullinated α-enolase peptide-1 antibody (r = 0.143, p = 0.025). Gingival index was correlated with RA duration (r = 0.262, p < 0.001), ESR (r = 0.162, p = 0.009), anti-cyclic citrullinated peptide antibody (r = 0.203, p = 0.004) and anti-citrullinated α-enolase peptide-1 antibody (r = 0.225, p < 0.001). Periodontal structural damage represented by probing pocket depth and clinical attachment level were less in RA patients with human leukocyte antigen (HLA)-DRB1 shared epitope compared than those without shared epitope (p = 0.005 and p =0.006, respectively).

CONCLUSIONS

The prevalence of moderate or severe periodontitis was increased in RA patients compared to controls. Periodontal inflammation was correlated with RA disease duration, ESR, and anti-citrullinated protein antibodies. Periodontal structural damage was less in RA patients with HLA-DRB1 shared epitope.

Clinical analysis of 56 patients with rhupus syndrome: manifestations and comparisons with systemic lupus erythematosus: a retrospective case-control study

To investigate the clinical features of Rhupus syndrome, we retrospectively reviewed the medical records of 56 patients with Rhupus who were hospitalized at the Peking Union Medical College Hospital, Beijing, China, between January 2000 and March 2013. We analyzed the clinical manifestations of Rhupus syndrome and compared these with a control group of 160 randomly selected systemic lupus erythematosus (SLE) patients without coexisting rheumatoid arthritis (RA). In our center, 1.30% (56/4301) of hospitalized SLE patients had Rhupus syndrome. The median disease duration was 8.0 years and 83.9% had RA onset. All Rhupus patients showed radiological erosion in the joints. Compared with the control group, Rhupus patients had a longer disease duration, higher prevalence of anticyclic citrullinated peptide antibody and rheumatoid factor, higher incidence of symmetrical polyarthritis with more joint deformities and rheumatic nodules, and increased erythrocyte sediment rate and c-reactive protein levels (P < 0.005). In addition, a lower SLE disease activity index and incidences of malar rash, hemolytic anemia, renal and neurological involvement (P < 0.005), and hypocomplementemia (P < 0.05) was observed in the Rhupus group.Rhupus syndrome is rare in SLE patients. Most Rhupus patients had RA onset and a distinctive clinical profile characterized by more severe RA-associated and mild SLE-associated damage. Specific autoantibodies and imaging findings could be helpful for making accurate Rhupus diagnoses.

The influence of polygenic risk scores on heritability of anti-CCP level in RA

The objective of this study was to study genetic factors that influence quantitative anticyclic citrullinated peptide (anti-CCP) antibody levels in RA patients. We carried out a genome-wide association study (GWAS) meta-analysis using 1975 anti-CCP+ RA patients from three large cohorts, the Brigham Rheumatoid Arthritis Sequential Study (BRASS), North American Rheumatoid Arthritis Consortium (NARAC) and the Epidemiological Investigation of RA (EIRA). We also carried out a genome-wide complex trait analysis (GCTA) to estimate the heritability of anti-CCP levels. GWAS-meta-analysis showed that anti-CCP levels were most strongly associated with the human leukocyte antigen (HLA) region with a P-value of 2 × 10(-11) for rs1980493. There were 112 SNPs in this region that exceeded the genome-wide significance threshold of 5 × 10(-8), and all were in linkage disequilibrium (LD) with the HLA- DRB1*03 allele with LD r(2) in the range of 0.25-0.88. Suggestive novel associations outside of the HLA region were also observed for rs8063248 (near the GP2 gene) with a P-value of 3 × 10(-7). None of the known RA risk alleles (∼52 loci) were associated with anti-CCP level. Heritability analysis estimated that 44% of anti-CCP variation was attributable to genetic factors captured by GWAS variants. In summary, anti-CCP level is a heritable trait, and HLA-DR3 and GP2 are associated with lower anti-CCP levels.

A spectrum of susceptibility to rheumatoid arthritis within HLA-DRB1: stratification by autoantibody status in a large UK population

Previously-proposed rheumatoid arthritis (RA) HLA-DRB1 susceptibility and protective models were compared, based on amino acids at positions 67-74 and autoantibody combinations. 3 657 RA patients and 1 357 controls were studied using logistic regression, with secondary stratification by anti-citrullinated peptide antibodies(ACPA) and rheumatoid factor(RF). Susceptibility models were based on previously defined HLA-DRB1 shared epitope(SE) subgroups. (70)DERAA(74), D(70) and I(67) protective models were compared, adjusting for HLA-DRB1 SE. A hierarchy of risk was observed within the HLA-DRB1 SE, particularly for ACPA-positive and RF-positive RA: HLA-DRB1(*)0401∼(*)0404>(*)0101∼(*)1001 ((*)0404>(*)0101: P=0.0003). HLA-DRB1(*)0401/(*)0404 compound heterozygosity conferred a risk similar to (*)0401 homozygosity (P=0.70). Protective effects of D(70) and I(67) were similar. Predictions of the D(70) model fitted the data better than those of the I(67) model. The protective effect of D(70) showed a gene-dose effect (OR 0.82, 95% CI 0.73-0.92, P=5.8 × 10(-4)), but was only seen in RA patients positive for RF or ACPA. HLA-DRB1 SE alleles were also associated with ACPA-negative, RF-positive RA (OR 1.42 (1.15-1.76), P=0.0012). In conclusion, HLA-DRB1 SE alleles show heterogeneity in RA susceptibility; their major effect appears to be mediated by ACPA positivity, but a significant association of HLA-DRB1 SE with RF-positive, ACPA-negative RA was also observed. D(70) specifically protected against antibody-positive RA.

Autoantibodies in rheumatoid arthritis: rheumatoid factors and anticitrullinated protein antibodies

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease, characterized by chronic, erosive polyarthritis and by the presence of various autoantibodies in serum and synovial fluid. Since rheumatoid factor (RF) was first described, a number of other autoantibodies have been discovered in RA patients. The autoantigens recognized by these autoantibodies include cartilage components, chaperones, enzymes, nuclear proteins and citrullinated proteins. However, the clinical significances and pathogenic roles of these antibodies are largely unknown except for RF and anticitrullinated protein antibodies (ACPAs), whose clinical usefulness has been acknowledged due to their acceptable sensitivities and specificities, and prognostic values. This review presents and discusses the current state of the art regarding RF and ACPA in RA.