However, IL-22 also can be deleterious, depending on its expression with other cytokines such as IL-17A,22 which has been implicated in lung cancer,23,24 emphysema,25, 26, 27 and allergic diseases.28, 29, 30 Therefore, it is important to understand the context of IL-22 expression and how it is controlled during a pulmonary insult. This evidence concerns the gene IL22 and pulmonary emphysema.