CDE challenge increases CXCL mRNA expression in the lung and CXCR1/2 in bone marrow of sensitized mice
Mice were sensitized to CDE by subjecting them to CDE-MCM (Fig 1A )31,34. Compared to PBS challenge (Fig 1A left panel), CDE challenge (Fig 1A middle panel) in these sensitized mice induced much greater lung expression levels of Cxcl1 , Cxcl2 ,Cxcl3 , and Cxcl5 at 2 h and/or 4 h, but not Cxcl4and Cxcl7 (sup Fig2A ). A shared feature of these upregulated Cxcl1 , Cxcl2 , Cxcl3 , and Cxcl5chemokines is that they bind CXCR1 and CXCR237,38. We reasoned that expression and secretion of these Cxclchemokines in the lungs should increase in the number of progenitor cells expressing CXCR1 and CXCR237,38in the bone marrow to prepare them for migration to the lungs. To test this hypothesis, we examined the time kinetics of CDE challenge-induced upregulation of Cxcr1 and Cxcr2 mRNA expression in bone marrow of sensitized mice. CDE challenge increased the mRNA expression of Cxcr1 and Cxcr2 in bone marrow cells at 16 h post-CDE challenge (sup Fig2B ), suggesting that these receptors play a role in recruiting inflammatory cells from bone marrow to the lungs.