Circulating Tfh cells are differentially modified by abatacept or TNF blockers, and predict treatment response in Rheumatoid Arthritis.

OBJECTIVE: CD4+CXCR5+PD-1hi follicular helper T (Tfh) cells dwell in the germinal centers (GCs) of lymphoid organs and participate in Rheumatoid Arthritis (RA) pathogenesis; the frequency of their circulating counterparts (cTfh-frequency) is expanded in RA and correlates with the pool of GC Tfh cells. Our objective was to study the effect of abatacept (ABT) or TNF blockers (TNFb) on the cTfh-frequency in RA.

METHODS: Peripheral blood was drawn from seropositive-longstanding RA patients chronically receiving csDMARDS (n = 45), TNFb (n = 59), or ABT (n = 34), and healthy controls (HC) (n = 137). Also, patients with an incomplete response to csDMARDS (n = 41) who initiated TNFb (n = 19) or ABT (n = 22), were studied at 0 and 12 months. The cTfh-frequency was examined by cytometry.

RESULTS: As compared with HC, an increased cTfh-frequency was seen in seropositive-longstanding RA chronically receiving csDMARDs or TNFb but not ABT. After escalating from csDMARDs, the cTfh-frequency did not vary in patients who were given TNFb but decreased to HC levels in those given ABT. In the ABT group, the baseline cTfh-frequency was higher for patients who attained 12M remission (12Mr), vs those who remained active (12Ma): 0m cutoff for remission >0.38% (Sens. 92%, Sp. 90%), OR 25.3. Conversely, in the TNFb group, the baseline cTfh-frequency was lower for 12Mr vs 12Ma: 0m cutoff for non-remission >0.44% (Sens. 67%, Sp. 90%), OR 8.5.

CONCLUSION: ABT but not TNFb, is able to curtail the cTfh-frequency in RA. A higher baseline cTfh-frequency predicts a good response to ABT but a poor response to TNFb.