Consistent with these findings, PM exposure in juvenile mice exacerbated the OVA-induced asthma response in adult mice, as evidenced by increased neutrophil and eosinophil inflammation and airway mucus secretion in lung tissues, as well as elevated levels of Th2 cytokines and chemokines in mRNA (IL-4, IL-5, IL-13, IL-33, Ccl11/Eotaxin, Ccl3/MIP-1α, CXCL1/KC and CXCL2) or protein (IL-4, IL-5, IL-13, IL-6, IL-10 and KC). Here, CXCL1 is linked to asthma.