The correlation between IL-20 and the Th2 immune response in human asthma.

Backround: Interleukin-20 (IL-20) belongs to the IL-10 family, which has been shown to be crucial in immune responses, regulation of inflammatory responses, hemopoiesis, and epidermal cell and keratinocyte differentiation. However, the role of IL-20 in asthma remains unclear. Here, our aim is to evaluate the correlation between IL-20 and the Th2 immune response in human.

Methods: In this study, we recruited 100 asthma patients and 100 control subjects for collection of serum samples and biopsy material. Firstly, We observed the expression of IL-20 in the airway epithelium of asthma patients by immuno-histochemical analysis, and then used an enzyme-linked immune-sorbent assay (ELISA) to analyze the serum levels of IL-20, IL-4, IL-5 and IL-13 in patients with asthma.

Results: We found high levels of expression of IL-20 in the airway epithelium of asthma patients. We also found that the concentrations of IL-20 and the Th2 cytokines, IL-4, IL-5 and IL-13, were significantly higher in patients with asthma and a positive correlation were found between IL-20 and Th2 cytokines (IL-4, IL-5, and IL-13). Furthermore, levels of IL-20 gradually increased according to the severity of the asthma.

Conclusions: IL-20 levels are increased in the epithelium and serum of asthmatic patients. The correlation between IL-20 levels and Th2 cytokines suggests that IL-20 may play a patho-physiologic role in the Th2 immune response in human asthma and may be a potential biomarker of asthma severity.