Biomarkers in autoimmune rheumatic diseases

Incidence and Clinical Pattern of Mixed Connective Tissue Disease in Sudanese Patients at Omdurman Military Hospital: Hospital-Based Study

Background

Mixed connective tissue disease (MCTD) is a rare autoimmune disease, characterized by the production of specific autoantibody anti-RNP, which presents with varied overlapping symptoms of different connective tissue disorders. The aim of this study is to identify the frequency and patterns of MCTD.

Methods

This is a descriptive cross-sectional hospital-based study conducted at the rheumatology clinic at Omdurman Military Hospital between February 2019 and July 2019. The study included 30 patients and data were collected using a designated questionnaire.

Results

The study showed that the majority of patients (96.7%) were females and only 3.3% was male. About 30% of the patients aged between 30 and 39 years were the most affected. As a first diagnosis, 10% of the patients had a MCTD fulfilling the Alarcon-Segovia criteria. The remaining 90% of the patients were diagnosed with other diseases before evolving into MCTD. The most common clinical presentation was arthralgia in 100% of the patients, 90% were symmetrically followed by myositis in 70% of the patients, arthritis in 63.3% of the patients, puffy fingers in 63.3% of the patients, and hand swelling in 60% as major musculoskeletal symptoms. Regarding the initial results in immunological profile, the most common positive autoantibodies among the patients were anti-RNP titer in 96.7% of the patients, ANA in 90%, anti-Sm in 50%, RF in 50%, anti-Ds DNA in 46.7%, and anti-Ro in 43.3%.

Conclusion

This study showed that MCTD is more common in females, only 10% of patients presented with a fulfilling criteria of the disease at diagnosis, and the rest of the patients presented with other rheumatologic diseases before evolving into MCTD.

NLRP3 and CARD8 Polymorphisms Influence Higher Disease Activity in Rheumatoid Arthritis

Background

The activation of NLRP3-inflammasome may contribute to inflammatory processes in rheumatoid arthritis (RA). Functional polymorphisms in the genes coding for its components NLRP3 and CARD8 were associated with a proinflammatory phenotype. Our aim was to investigate the influence of these polymorphisms on RA susceptibility and disease activity at the time of diagnosis and after six months of treatment.

Methods

A group of 128 RA patients treated with methotrexate and 122 healthy controls were genotyped for NLRP3 rs35829419 (p. Q705K) and CARD8 rs2043211 (p. C10X) polymorphisms.

Results

RA susceptibility was not influenced by the investigated polymorphisms or their interaction. The investigated polymorphisms explained 8% of variability in DAS28 at the time of diagnosis. Carriers of NLRP3 rs35829419 or CARD8 rs2043211 polymorphisms had significantly higher DAS28 at the time of diagnosis (p=0.003; p=0.022; respectively). Polymorphic CARD8 rs2043211 TT genotype was also associated with higher DAS28 after six months of treatment (p=0.033).

Conclusions

Genetic variability of inflammasome components may contribute to higher disease activity at the time of diagnosis and after 6 months of methotrexate treatment in RA patients. Better understanding of the immunological mechanisms behind a more active course of RA may suggest novel treatment approaches in a subset of patients with a proinflammatory phenotype.