BAL alveolar macrophages from severe COVID-19 patients (n = 23) were characterized by an increased production and release of several pro-inflammatory mediators, such as IL-1β, IL-6, CCL3 and CCL4 and increased expression of IL-1R and S100A8/9 proteins, compared to those from mild COVID-19 patients [118]. Here, IL1R1 is linked to COVID-19.