Despite the worldwide effect of the Coronavirus disease 2019 (COVID-19) pandemic, the underlying mechanisms of fatal viral pneumonia remain elusive. Here, we show that critical COVID-19 is associated with enhanced eosinophil-mediated inflammation when compared to non-critical cases. In addition, we confirm increased Th2-biased adaptive immune responses, accompanying overt complement activation, in the critical group. Moreover, enhanced antibody responses and complement activation is associated with disease pathogenesis as evidenced by formation of immune complexes and membrane attack complexes in airways and vasculature of lung biopsies from six fatal cases, as well as by enhanced hallmark gene set signatures of FcγR signaling and complement activation in myeloid cells of respiratory specimens from critical COVID-19 patients. These results suggest that SARS-CoV-2 infection may drive specific innate immune responses, including eosinophil-mediated inflammation, and subsequent pulmonary pathogenesis via enhanced Th2-biased immune responses, which might be crucial drivers of critical disease in COVID-19 patients.
BackgroundThe development of non-caseating epithelioid cell granulomas in cancer patients who do not fulfill the systemic sarcoidosis criteria is termed sarcoid-like reaction (SLR). Little is known about this condition's natural course and impact on the prognosis of malignancy. We aimed to investigate the natural course and prognostic value of cancer-associated SLR.MethodsClinical data were retrospectively analyzed in 32 patients with biopsy-proven cancer-associated SLR. Among patients with non-small cell lung cancer (NSCLC), SLR cases (n = 8) were matched with non-SLR cases (n = 78) for survival analysis.ResultsAmong the included patients, the mean age was 59.7 years, and 68.8% were female. The median follow-up period was 35.6 months [interquartile range (IQR): 14.0–61.4 months]. Of all the included malignancies (n = 32), breast cancer (25.0%) and NSCLC (25.0%) were the most common, with stage I being the most frequent tumor stage (59.4%). During follow-up, SLR progression to overt sarcoidosis was not observed. In the 28 patients with available follow-up computed tomography images (median interval: 24.9 months; IQR: 14.4–41.7), 4 patients received corticosteroids (n = 4), resulting to a decrease of SLR lesions. Meanwhile, among those who did not receive treatment (n = 24), the extent of SLR decreased or did not change in 85.7% of them, whereas 3.6% had increased SLR extent. Furthermore, among patients with NSCLC, SLR was not associated with overall survival [hazard ratio (HR) = 1.28, 95% confidence interval (CI): 0.02–67.71, P = 0.882] and recurrence of malignancy (HR = 1.27, 95% CI 0.21–7.51, P = 0.793) in the Cox proportional hazard regression model.ConclusionsDuring the follow-up of cancer-related SLR, we found no further evidence for systemic sarcoidosis, and most of the lesions decreased or did not change. Development of SLR was also not associated with overall survival or disease-free survival in patients with NSCLC.
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