HMOX1 and bacterial infectious disease: Since IL-1β is an important cytokine for protection against bacterial infection, including L. monocytogenes clearance in vivo34, and since its expression can be regulated by HO-1, we examined whether soluble Tim-3 had any effect on IL-1β mRNA levels in RAW264.7 cells during L. monocytogenes infection and found that it caused an increase that was prevented by the HO-1 inhibitor Snpp-IX35 (Fig. 5E).