Marijnissen et al. (2011) reported IL-22 and IL-22 receptor levels to be increased in synovial tissue during inflammation. On another note, IL-22 promoted the expression of IFN-γ, thereby inhibiting intestinal coronavirus replication (Xue et al., 2017). IL-22 and IFN-γ have been shown to suppress pulmonary inflammation in pneumonia caused by Pseudomonas aeruginosa (Broquet et al., 2020). The therapeutic benefits of IL-22 pathway activation have been demonstrated in experimental colitis (Lamas et al., 2016). Here, IL22 is linked to pneumonia.