Early studies found IL-22 upregulation in many inflammatory conditions such as rheumatoid arthritis (Roeleveld and Koenders, 2015), psoriasis (Wolk et al., 2006; Gordon et al., 2019), inflammatory bowel disease (Mizoguchi et al., 2018), asthma (Besnard et al., 2011), and hyperIgE/STAT3 mutation (Schroder, 2010), suggesting promotion of pro-inflammatory pathways. Here, IL22 is linked to asthma.