Expansion of Alternative Autoantibodies Does Not Follow the Evolution of Anti-Citrullinated Protein Antibodies in Preclinical Rheumatoid Arthritis: An Analysis in At-Risk First Degree Relatives

Disparities in rheumatoid arthritis outcomes for North American Indigenous populations

Advances in rheumatoid arthritis (RA) management have significantly improved clinical outcomes of this disease; however, some Indigenous North Americans (INA) with RA have not achieved the high rates of treatment success observed in other populations. We review factors contributing to poor long-term outcomes for INA with RA. We conducted a narrative review of studies evaluating RA in INA supplemented with regional administrative health and clinical cohort data on clinical outcomes and health care utilisation. We discuss factors related to conducting research in INA populations including studies of RA prevention. NA with RA have a high burden of genetic and environmental predisposing risk factors that may impact disease phenotype, delayed or limited access to rheumatology care and advanced therapy. These factors may contribute to the observed increased rates of persistent synovitis, premature end-stage joint damage and mortality. Novel models of care delivery that are culturally sensitive and address challenges associated with providing speciality care to patients residing in remote communities with limited accessibility are needed. Progress in establishing respectful research partnerships with INA communities has created a foundation for ongoing initiatives to address care gaps including those aimed at RA prevention. This review highlights some of the challenges of diagnosing, treating, and ultimately perhaps preventing, RA in INA populations.

Increased frequency of TIGIT+ CD4 T Cell subset in autoantibody-positive first-degree relatives of patients with rheumatoid arthritis

Background

Despite immune cell dysregulation being an important event preceding the onset of rheumatoid arthritis (RA), the phenotype of T and B cells in preclinical RA is less understood. The aim of this study was to characterize T and B cell populations in RA patients and their autoantibody (aAb) negative and positive first-degree relatives (FDR).

Methods

Cryopreserved peripheral blood mononuclear cells (PBMCs) collected at scheduled visits from aAb-(n=25), and aAb+ FDR (n=10) and RA patients (n=13) were thawed and stained using optimized antibody cocktails as per a specific 13-color T or B cell panel. Immunophenotyping was performed using a Cytoflex LX (Beckman-Coulter) flow cytometer and FlowJo software was used for analyzing the frequency of immune cell populations.

Results

Multicolor flow cytometry experiments identified an increased TIGIT expression in circulating lymphocytes of aAb+ FDR and RA patients, relative to aAb- FDR (P<0.01). These TIGIT⁺ T cells exhibited a memory phenotype and expressed high levels of PD-1, ICOS, HLA-DR, CXCR3 and CXCR5. Moreover, increased TIGIT⁺ CD4 T cell frequency correlated with the frequency of PD-1⁺ CD4 T cells (r = 0.4705: P = 0.0043) and circulating levels of ACPA and RF. We also identified a decreased frequency of CD27+IgD- switched memory B cells in RA patients (P < 0.01), while increased frequency of TIGIT+ CD4 T cells in FDR correlated with the frequency of PD1⁺PTEN⁺ B cells (r = 0.6838, P = 0.0004) and autoantibody positivity (P = 0.01).

Conclusion

We demonstrate TIGIT as a distinct CD4 T cell marker for differentiating aAb- FDR from aAb+FDR and might play a critical role in regulating T and B cell crosstalk in preclinical RA.

New insights into the taxonomy of autoimmune diseases based on polyautoimmunity

OBJECTIVE

The clinical coexistence of two or more autoimmune diseases (ADs) fulfilling classification criteria is termed "overt polyautoimmunity" (PolyA), whereas the presence of autoantibodies unrelated to an index AD, without clinical criteria fulfillment, is known as "latent PolyA". We aimed to explore a new taxonomy of ADs based on PolyA.

METHODS

In a cross-sectional study of 292 subjects, we evaluated the presence of PolyA in 146, 45, 29, 17, and 17 patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), autoimmune thyroid disease (AITD) and systemic sclerosis (SSc), respectively, and 38 healthy controls. Clinical assessment, autoantibody profile (by autoantigen array chip), lymphocytes immunophenotype and cytokine profile (by flow cytometry) were evaluated simultaneously. A mixed cluster methodology was used to classify ADs.

RESULTS

Latent PolyA was more frequent than overt PolyA, ranging from 69.9% in RA to 100% in SSc. Nevertheless, both latent and overt PolyA clustered together. Over-expressed IgG autoantibodies were found to be hallmarks for the identification of index ADs. The combination of autoantibodies allowed high accuracy in the classification of ADs. Three well-defined clusters based on PolyA were observed with distinctive clinical and immunological phenotypes.

CONCLUSIONS

This proof-of-concept study indicates that ADs can be classified according to PolyA. PolyA should be considered in all studies dealing with ADs, including epidemiological, genetic, and clinical trials.