These co-cited references were divided into 7 clusters by CiteSpace: #0 (lipopolysaccharide-induced acute lung injury), #1 (danger signal), #2 (lung disease), #3 (nlrp3 inflammasome), #4 (severe COVID-19), #5 (epithelial cell), #6 (microbial infection) (Figure 7A). Here, NLRP3 is linked to COVID-19.