Is C5a a marker of inflammatory activity during clinical remission in patients with neuromyelitis optica spectrum disorders AQP4+?

MANIN, A; JUSTO, ME; PAZ, ML; VILLA, A

Congreso; 38th Congress of ECTRIMS 2022; 2022

Introduction:Neuromyelitis Optica Spectrum Disorders (NMOSD) is an antibody-mediated disorder of the Central Nervous System where aleading role of the complement system has been demonstrated. OBJECTIVE: To measure the levels of complement factors C3, C4 and C5a in serum andplasma of clinically stable patients with AQP4-IgG+ NMOSD. SUBJECTS/METHODS: Twelve patients with NMOSD AQP4+ according to 2015 criteria from aGeneral Hospital in Buenos Aires, Argentina, were included in the study, and 19 age- and sex-matched healthy volunteers as a control group (HC). AQP4antibodies were measured in serum by CBA analysis. Fresh blood samples were centrifuged to obtain serum and plasma. C3, C4, and AQP4 antibodies weremeasured in the serum, whereas C5a was measured in the plasma, which was obtained using Futhan (BD FUT-175®, BD Biosciences, San Jose, CA, USA).RESULTS: The complement factors, C3, C4, and C5a were measured in all samples. The mean concentration of C3 was 130.7 mg/dl (SD 16.1 mg/dl), andthe mean concentration of C4 was 21.6 mg/dl (SD 4.8 mg/dl); both values were within the normal reference range (C3: 84–193 mg/dl; C4: 20–40 mg/dl) andwere not significantly different (p>0.05) from the mean levels in healthy controls (C3: 116.9 mg/dl; C4: 21.9 mg/dl). When analyzing the mean plasma levelof C5a, we found a statistically significant difference (p=0.0444) between the mean concentration of C5a in NMOSD patients (43.1 ng/ml; SD 48.7 ng/ml)and the HC group (17.7 ng/ml; SD 16.7 ng/ ml).CONCLUSIONS: In this study, we demonstrated a significant higher amount of C5a in the bloodstream ofAQP4-IgG+ NMOSD patients, when comparing to normal controls. This could suggest activation of the complement system during remission disease.