IL17A and asthma: Chitinase-like proteins are molecules strongly associated with severe asthma, neutrophilia and IL-17A.33–36 Following exposure to DRA allergen, mRNA expression of murine chitinase-like genes Chil1, Chil3 and Chil4 were upregulated in both BALB/c and C57BL/6 mice compared with PBS controls (Figure 3a).