These reports suggested that SLPI in asthma patients may exhibit an anti-inflammatory function in mild to moderate asthma, while a low SLPI level may contribute to exacerbating the Th2-type airway inflammation in severe asthma patients [12]. Consistent with these findings, our results further support that a low level of SLPI potentiates Th2 airway inflammation via the IL-33-dependent pathway through an innate immune response in models of airway inflammation. This evidence concerns the gene SLPI and asthma.