CCL2 and infection: For a more comprehensive assessment of the immune response to infection, we further parsed the immune and immune-related clusters into microglia (a brain contaminant), innate lymphoid cells/T cells (ILC/T), osteoclasts (a contaminant from the skull), monocytes (MCs) and monocyte-derived cells, resident macrophages (MPs; subdivided by CCL2 expression), and inflammatory macrophages (subdivided by IL1 receptor type 1 [IL1R1] expression; Figure 3A–C , and D lower panel).