FIG 7.

Neutrophils are essential for AXPN-mediated clearance of C. difficile. By use of the CDI model, anti-Ly6G, clone 1A8 antibody, or isotype control IgG was administered to mice 1 day prior to infection with C. difficile spores and treatment with AXPN or PBS. The antibodies were administered every 48 h for 4 days. (A) Thirty hours postinfection, the cecal contents were assessed for bacterial burden by qPCR analysis of the quantities of 16S rRNA gene copies of C. difficile relative to the total number of 16S rRNA gene copies in the cecal contents. Expression levels are shown relative to that of the PBS-treated group on a log₁₀ scale. (B and C) Toxin levels in the cecal contents were also assessed 30 h postinfection by ELISA. (D) Cecal tissues were harvested 30 h postinfection, and the relative changes in mRNA levels of the indicated genes were measured using qRT-PCR. Expression levels are shown relative to that of the PBS-treated group. Data are the mean ± SE (n = 3 to 5 mice/group) and are representative of results from two independent experiments. *, P < 0.05; **, P < 0.01; ***, P < 0.001, compared to results for the indicated groups.