Upregulation of IL-19 cytokine during severe asthma: a potential saliva biomarker for asthma severity

Interleukin (IL)-19, a designated IL-20 subfamily cytokine, has been implicated in inflammatory disorders including rheumatoid arthritis, psoriasis, and lately in asthma. Here, through the analysis of transcriptomic datasets of lung tissue of large asthmatic cohorts, we report that IL-19 expression level is upregulated in asthma and correlates with disease severity. The gene expression of IL-19 in lung tissue was significantly higher in severe and mild/moderate asthmatic compared to healthy controls. IL-19 protein level, however, was significantly higher in the blood and saliva of severe asthmatics compared to mild/moderate subgroups as measured by ELISA assay. Interestingly, IL-19 protein level was not affected by corticosteroid treatment in plasma. Our data provide insights into the potential use of IL-19 as a saliva marker for asthma severity and a potential therapeutic target.