Objective RA patients with anti-collagen antibodies (anti-CII) are characterised by acute RA onset (Mullazehi et al, ARD 2007) and early joint erosions (Mullazehi et al ART 2012), as well as increased production of TNF by peripheral blood mononuclear cells from anti-CII immune complexes (IC) in vitro (Mullazehi et al A&R 2006). We have previously (abstract EWRR 2012) shown that polymorphonuclear neutrophil granulocytes (PMN) react towards anti-CII IC. The aim was to investigate whether functional PMN responses are associated with the clinical acute onset RA phenotype.
Methods A set of 72 baseline patient sera (24 anti-CII positive, 24 anti-CII negative/RF positive and 24 anti-CII negative/RF negative) was chosen from a clinically well-characterised RA cohort with 2-year radiological follow-up (Larsen score). PMN and PBMC isolated from healthy donors were stimulated with anti-CII IC prepared with sera from the patients. PMN expression of CD16 and CD66b were measured by flow cytometry, and PMN production of myeloperoxidase (MPO) and IL-17, and PBMC production of TNF was measured with ELISA.
Results CD66b, MPO, and TNF were significantly up-regulated and CD16 was significantly down-regulated by IC made with anti-CII positive sera. Even anti-CII low positive sera were able to impact the expression of CD16, CD66b and TNF. There was linear correlation to CD16, CD66b, MPO and TNF production in relation to anti-CII levels (r = -0.3152, 0.6755, 0.2532 and 0.5846, respectively). CD16 correlated with early joint erosion (p = 0.024, 0.034, 0.046 at baseline, one and two years) and CD66b was associated with changes in joint erosion (p = 0.017 and 0.016, at one and two years compared to baseline, respectively). CD66b was associated with baseline CRP and PBMC production of TNF was associated with baseline ESR, in accordance to our earlier findings. No correlations were observed with IL-17.
Conclusion We have earlier shown that PBMC anti-CII IC-induced production of TNF was associated with CRP and ESR in newly diagnosed RA patients. Here we show that PMN reactivity against anti-CII IC is uniquely associated with joint destruction. PMN reactivity towards anti-CII IC in cartilage of patients can contribute to joint destruction in newly diagnosed RA patients.
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