Microparticles: potential new contributors to the pathogenesis of systemic sclerosis?

BACKGROUND: Microparticles (MPs) are membrane-derived vesicles released from cells undergoing activation or apoptosis with diverse proinflammatory and prothrombotic activities, that have been implicated in the pathogenesis of systemic sclerosis (SSc). We aimed to evaluate the plasma levels of platelet-derived microparticles (PMPs), endothelial cell-derived microparticles (EMPs), and monocyte-derived microparticles (MMPs) in SSc patients, and the association between MPs and the clinical features of SSc. METHODS: In this cross-sectional study, 70 patients with SSc and 35 age- and sex-matched healthy controls were evaluated. Clinical and nailfold capillaroscopy (NFC) data were obtained from all patients. Plasma levels of PMPs (CD42+/31+), EMPs (CD105+), and MMPs (CD14+) were quantified by flow cytometry. RESULTS: Patients were mainly females (90%), with a mean age of 48.9 years old. PMP, EMP, and MMP levels were significantly increased in SSc patients compared to controls (79.2% ± 17.3% vs. 71.0% ± 19.8%, p = 0.033; 43.5% ± 8.7% vs. 37.8% ± 10.4%, p = 0.004; and 3.5% ± 1.3% vs. 1.1% ± 0.5%, p < 0.0001, respectively). PMP levels were significantly higher in patients with positive anti-topoisomerase-I antibodies (p = 0.030) and in patients with a disease duration > 3 years (p = 0.038). EMP levels were lower in patients with a higher modified Rodnan skin score (p = 0.015), and in those with an avascular score > 1.5 in NFC (p = 0.042). CONCLUSION: The increased levels of PMPs, EMPs and MMPs in scleroderma patients might indicate a possible role for these agents in the pathogenesis of this challenging disease.

Severity and mortality of COVID-19 in patients with systemic sclerosis: a Brazilian multicenter study.

INTRODUCTION: COVID-19 may be associated with greater severity and mortality in patients with systemic sclerosis (SSc). The present study aimed to evaluate the prevalence, severity and mortality of COVID-19 in a Brazilian cohort of SSc patients. METHODS: This multicenter, retrospective, observational study included 1,042 SSc patients followed in four centers of São Paulo between March 2020 and June 2021. Diagnosis of COVID-19 was established by proper positive RT-PCR testing or by highly suspicious infection. Patients were grouped into mild (outpatient setting treatment and no need for oxygen support) and moderate-to-severe (hospitalization and/or need for oxygen support) COVID-19. RESULTS: Of the 1,042 SSc patients, 118 patients were diagnosed with COVID-19. Interstitial lung disease (SSc-ILD) was present in 65.6% of the total cohort and in 46.3% of SSc patients with COVID-19. There were 78 (66.1%) cases of mild COVID-19, and 40 (33.9%) cases of moderate-to-severe disease, with 6 (5.1%) deaths. By univariate analysis, pulmonary arterial hypertension (OR 9.50, p=0.006), SSc-ILD (OR 3.90, p=0.007), FVC <80% (OR 2.90, p=0.01), cardiac involvement (OR 5.53, p=0.003), and use of rituximab (OR 3.92, p=0.039), but not age, gender, comorbidities or use of corticosteroids, were predictors of worse outcome for COVID-19. Using multivariate analysis, only SSc-ILD was significantly associated to a higher risk of moderate-to-severe COVID-19 (OR 2.73, 95% CI 1.12-6.69, p=0.02). Forty percent of the patients remained with symptoms after presenting COVID-19, predominantly dyspnea and/or cough (17%). CONCLUSION: In this cohort of patients with SSc, those with SSc-ILD were highly impacted by COVID-19, with a higher risk of moderate-to-severe COVID-19 infection and death.