Antiphospholipid antibody carriers and patients with quiescent antiphospholipid syndrome show persistent subclinical complement activation

OBJECTIVES

Complement activation has been advocated as one mechanism by which antiphospholipid antibodies (aPLs) can induce thrombosis. In patients with catastrophic aPL syndrome or re-thrombosis, enhanced complement activation was shown, even in quiescent phase of the disease. We aimed to assess complement activation and to investigate its association to clinical variables in aPL positive patients with a favorable disease course.

METHODS

Subjects with at least two consecutive positive aPL antibody results obtained ≥12 weeks apart were enrolled. They were subjects without history of thrombosis or pregnancy morbidity (aPL carriers), patients with pregnancy morbidity alone (OAPS), and/or with arterial, venous, or small-vessel thrombosis (TAPS); all patients should have been free of symptoms for ≥2 years. Patients affected with systemic autoimmune diseases were excluded. Healthy age and sex-matched subjects were included as controls. Plasma C5a and C5b-9 levels were assessed by commercially available ELISA assays. Non-parametric Mann-Whitney test and Spearman's correlation were applied.

RESULTS

Thirty-seven OAPS, 38 TAPS, 42 aPL carriers, and 30 healthy subjects were enrolled. Median C5a and C5b-9 levels were significantly higher in quiescent aPL positive patients (OAPS, TAPS, aPL carriers) compared with controls: C5a ng/ml 10.61 (IQR 6.87-15.46) vs 4.06 (2.66-7.35), p< 0.001; C5b-9 ng/ml 283.95 (175.8-439.40) vs 165.90 (124.23-236.8), p< 0.001. Similar C5a and C5b-9 levels were observed in OAPS and TAPS patients and aPL carriers. A positive correlation between C5b-9 median levels and the number of aPL positive tests was found (p= 0.002).

CONCLUSIONS

The persistence of aPL antibodies is associated to a persistent subclinical activation of the complement cascade.

Autoinflammatory Diseases and COVID-19 Vaccination: Analysis of SARS-CoV-2 Anti-S-RBD IgG Levels in a Cohort of Patients Receiving IL-1 Inhibitors

The purpose of the study was to evaluate the antibody response after COVID-19 vaccination in patients affected by systemic autoinflammatory diseases (SAID) undertaking IL-1 inhibitors (IL-1i) compared to healthy vaccinated controls (HC). The course of COVID-19 in vaccinated patients on IL-1i was also assessed. The serological response was evaluated in SAID patients using the CLIA MAGLUMI TM 2000 Plus test after the first vaccination cycle and the booster dose. Fifty-four fully vaccinated healthcare workers were enrolled as HCs. GraphPad Prism 8 software was used for statistical analysis. All patients developed an adequate antibody response. No differences were observed between the antibody titers of patients on IL-1i and those not on IL-1i, either after the first vaccination cycle or the booster dose (p = 0.99), and to HC (p = 0.99). With increasing age, a decrease in antibody production was assessed after the second vaccine in SAID (r = 0.67, p = 0.0003). In general, 11.6% of SAID patients had COVID-19 after receiving vaccination. None of them developed severe disease or experienced flares of their autoinflammatory disease. In conclusion, patients receiving IL-1i develop an antibody response comparable to HC. No side effects after vaccination were observed; IL-1i was continued before and after injections to avoid flare-ups.