Abstract

INTERACTION OF VARIOUS CITRULLINATED ANTIBODIES EMPHASIZING THE INFLUENCE OF ANTI-SA TOWARDS DISEASE ACTIVITY IN SOUTH INDIAN RHEUMATOID ARTHRITIS CASES

Venkatraman Malini*, Narayanasamy Shettu, Subbiah Murugesan and Gyanendra Bahadur Chand

ABSTRACT

Understanding of rheumatoid arthritis (RA) has greatly advanced after anti-cyclic citrullinated peptide (anti-CCP) discovery. However, the exact nature of citrullinated antibody contributing to disease activity remains obscure. Intracellular synovial presence of citrullinated vimentin and α-enolase makes them relevant candidates for antibody trigger. Hence, aimed at evaluating the synergistic interactions of various citrullinated antibodies and identify which uniquely contribute towards clinical manifestation. Blood samples and demographics collected with informed consent from 301 South Indian RA cases satisfying 2010 revised American College of Rheumatology (ACR) criteria. Analysed C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), anti-CCP, anti-Sa, anti-citrullinated α-enolase peptide-1 (CEP-1) and disease activity score-28 (DAS-28). Overall frequency of RF, anti-CCP, anti-Sa and anti-CEP-1 were 83.7%, 80.1%, 58.5% and 61.1% respectively. Comparing and contrasting of studied citrullinated antibodies appropriately in various combinations like, 44.5% triple positive cases (anti-CCP(+), anti-Sa(+) and anti-CEP-1(+)), 16.9% triple negative cases, 12.2% anti-CCP(+), anti-Sa(+) and anti-CEP-1(-) cases, 15.3% anti-CCP(+), anti-CEP-1(+) and anti-Sa(-) cases, and 7.9% anti-CCP(+) alone cases were performed. Analysis revealed triple positive cases had significant anti-CCP, DAS-28 and inflammatory markers (p<0.05) to anti-CCP(+) alone cases, enlightening synergistic interaction of antibodies. While delineating the individual effect of antibodies, anti-CEP-1 significantly elevated anti-CCP (p<0.05) not RF and DAS-28. Contrastingly, anti-Sa displayed remarkably unique connection to RF and DAS-28 (p<0.05). This is the first report in Indian population, designating anti-Sa as disease activity marker. Anti-Sa has the prospect for wider use in diagnosis and prognosis in identifying RA patients who may soon progress to aggressive disease.

Keywords: Anti-CCP, anti-Sa, anti-CEP-1, DAS-28, rheumatoid arthritis, RF.