Peters, Noah F.

ObjectiveWhile thrombosis and pregnancy loss are the best‐known clinical features of antiphospholipid syndrome (APS), many patients also exhibit “extra‐criteria” manifestations, such as thrombocytopenia. The mechanisms that drive APS thrombocytopenia are not completely understood, and no clinical biomarkers are available for predicting antiphospholipid antibody (aPL)–mediated thrombocytopenia. Calprotectin is a heterodimer of S100A8 and S100A9 that is abundant in the neutrophil cytoplasm and released upon proinflammatory neutrophil activation. Here, we sought to evaluate the presence, clinical associations, and potential mechanistic roles of circulating calprotectin in a cohort of primary APS and aPL‐positive patients.MethodsLevels of circulating calprotectin were determined in plasma by the QUANTA Flash chemiluminescent assay. A viability dye‐based platelet assay was used to assess the potential impact of calprotectin on aPL‐mediated thrombocytopenia.ResultsCirculating calprotectin was measured in 112 patients with primary APS and 30 aPL‐positive (without APS criteria manifestations or lupus) patients as compared to patients with lupus (without APS), patients with unprovoked venous thrombosis (without aPL), and healthy controls. Levels of calprotectin were higher in patients with primary APS and aPL‐positive patients compared to healthy controls. After adjustment for age and sex, calprotectin level correlated positively with absolute neutrophil count (r = 0.41, P < 0.001), positively with C‐reactive protein level (r = 0.34, P = 0.002), and negatively with platelet count (r = −0.24, P = 0.004). Mechanistically, we found that calprotectin provoked aPL‐mediated thrombocytopenia by engaging platelet surface toll‐like receptor 4 and activating the NLRP3‐inflammasome, thereby reducing platelet viability in a caspase‐1‐dependent manner.ConclusionThese data suggest that calprotectin has the potential to be a functional biomarker and a new therapeutic target for APS thrombocytopenia.image

ObjectiveThis study assessed patient‐reported outcomes (PROs) in individuals with persistently positive antiphospholipid antibodies (aPL) to better understand how living with aPL may affect their quality of life.MethodsPatients completed Patient‐Reported Outcomes Measurement Information System Physical Function (PF) and Cognitive Function (CF) Short Forms as well as the pain intensity (PI) rating (scale of 1‐10). Patients were characterized for demographics, clinical manifestations of antiphospholipid syndrome (APS), cardiovascular risk factors, laboratory test results, and medication usage. Multivariate modeling was done via linear regression.ResultsOf 139 patients, 89 had primary APS, 21 had secondary APS, and 29 had persistent aPL without meeting clinical criteria for APS. The average T scores (±SD) for PF and CF were 45.4 ± 9.2 and 48.6 ± 11.6, respectively; the average for PI was 3.0 ± 2.6. Approximately half of the patients (47%) endorsed at least mild impairment in PF (T score < 45). Mean PF, CF, and PI did not differ between diagnostic groups. Individuals who endorsed more impairment on one measure also tended to endorse more impairment on another (Pearson r = 0.43‐0.59). In the multivariate models, age, smoking, pain medications, and serotonergic medications were associated with impairment in at least one PRO domain. The Damage Index for APS was significantly correlated with both PF and CF.ConclusionIndividuals living with APS endorsed more impairment in PF (and potentially CF) than expected for the general population. The relationship between certain medications and PROs warrants further study, as does the longitudinal trajectory of these and other PROs.