Systemic phenotype related to primary Sjögren's syndrome in 279 patients carrying isolated anti-La/SSB antibodies

OBJECTIVES

To evaluate the systemic phenotype associated with the presence of isolated anti-La/SSB antibodies in a large international registry of patients with primary Sjögren's syndrome (pSS) fulfilling the 2002 classification criteria.

METHODS

The Big Data Sjögren Project Consortium is an international, multicentre registry created in 2014. Baseline clinical information from leading centres on clinical research in SS of the 5 continents was collected. Combination patterns of anti-Ro/SSA-La/SSB antibodies at the time of diagnosis defined the following four immunological phenotypes: double positive (combined Ro/SSA and La/SSB,) isolated anti-Ro/SSA, isolated anti-La/SSB, and immunonegative.

RESULTS

The cohort included 12,084 patients (11,293 females, mean 52.4 years) with recorded ESSDAI scores available. Among them, 279 (2.3%) had isolated anti-La/SSB antibodies. The mean total ESSDAI score at diagnosis of patients with pSS carrying isolated anti-La/SSB was 6.0, and 80.4% of patients had systemic activity (global ESSDAI score ≥1) at diagnosis. The domains with the highest frequency of active patients were the biological (42.8%), glandular (36.8%) and articular (31.2%) domains. Patients with isolated anti-La/SSB showed a higher frequency of active patients in all ESSDAI domains but two (articular and peripheral nerve) in comparison with immune-negative patients, and even a higher absolute frequency in six clinical ESSDAI domains in comparison with patients with isolated anti-Ro/SSA. In addition, patients with isolated anti-La/SSB showed a higher frequency of active patients in two ESSDAI domains (pulmonary and glandular) with respect to the most active immunological subset (double-positive antibodies). Meanwhile, systemic activity detected in patients with isolated anti-La/SSB was overwhelmingly low. Even in ESSDAI domains where patients with isolated anti-La/SSB had the highest frequencies of systemic activity (lymphadenopathy and muscular), the percentage of patients with moderate or high activity was lower in comparison with the combined Ro/SSA and La/SSB group.

CONCLUSIONS

Patients carrying isolated La/SSB antibodies represent a very small subset of patients with a systemic SS phenotype characterised by a significant frequency of active patients in most clinical ESSDAI domains but with a relative low frequency of the highest severe organ-specific involvements. Primary SS still remains the best clinical diagnosis for this subset of patients.

Variants of the IL23R gene are associated with ankylosing spondylitis but not with Sjögren syndrome in Hungarian population samples

Recently, associations were found between several autoimmune diseases and functional variants of interleukin-23 receptor (IL23R) gene; here, we studied the possible association of nine polymorphisms of IL23R with ankylosing spondylitis (AS) and with Sjögren syndrome (SS). In our study, we genotyped groups of patients with AS (n = 206), SS (n = 156) and healthy controls (n = 235) for rs11805303, rs10889677, rs1004819, rs2201841, rs11209032, rs11209026, rs10489629, rs7517847 and rs7530511 variants using PCR-RFLP methods. We observed significant increase in the carriage of the T allele of rs11805303 and the A allele of rs1004189 in the AS group compared with the controls. For the rs10889677 variant, the prevalence of the AA genotype and for the rs2201841, the CC genotype showed a more than two-fold increase in the AS group compared with the controls. By contrast, the GA heterozygous genotype of rs11209026 variant showed a significant decrease in AS patients compared with controls. Haplotype analysis revealed association of four IL23R haplotypes with AS. There was no difference in the distribution of any of the examined IL23R variants between controls and SS patients. In conclusion, we confirmed the susceptibility or protective associations of IL23R polymorphisms with AS in a Hungarian population and first demonstrated the involvement of the rs11805303 intronic single nucleotide polymorphisms, which was tested so far only for other autoimmune diseases.

Anti-cyclic citrullinated peptide antibody isotypes in rheumatoid arthritis: association with disease duration, rheumatoid factor production and the presence of shared epitope

OBJECTIVE

Anti-cyclic citrullinated peptide (anti-CCP) antibodies of IgG isotype are specific diagnostic markers of rheumatoid arthritis (RA). Recent evidence also points to their direct involvement in the pathophysiology. Little information is available, however, regarding the isotype distribution of anti-CCP antibodies and the characteristics of IgA and IgM anti-CCP.

METHODS

IgG, IgA and IgM anti-CCP2 and rheumatoid factor (RF) levels were measured in the sera of 119 RA patients and 118 controls, including patients with other rheumatic diseases and healthy subjects. We analyzed the diagnostic performance of IgA and IgM anti-CCP2 antibodies and their relationship with IgG anti-CCP2, RFs, disease duration and the presence of HLA-DRB1 shared epitope (SE) alleles.

RESULTS

Patients with RA had significantly higher serum IgA and IgM anti-CCP2 antibody levels than healthy subjects and patients with other rheumatic diseases (p<0.0001). IgG, IgA and IgM anti-CCP2 antibodies were present in 74.8%, 52.9% and 44.5% of RA patients, and their diagnostic specificity was 95.8%, 95.8% and 91.6%, respectively. The presence of anti-CCP2 antibodies was significantly associated with SE alleles (p=0.03). The frequency of IgM anti-CCP2 positivity was lower in longstanding disease compared to early RA (p=0.03).

CONCLUSION

IgA and IgM anti-CCP2 antibodies are present in RA patients, and they are similarly specific for RA as IgG anti-CCP2. The higher frequency of IgM anti-CCP2 antibodies in early RA suggests that they are mostly generated during the first phase of immune response; nonetheless, their production seems to be sustained in some patients. Further analysis of IgM and IgA anti-CCP2 antibodies may provide insights into the pathogenesis of RA.