TLR4 ligand increased TNFα expression in lung and the bacterial killing activity of peritoneal cells. (A) Commensal depletion decreased TLR4 as well as TNFα mRNA expression in lung and LPS supplement reversed them. The values represent the average fold increase (± s.d.) in mRNA expression in 3 different mice of each group. ! p < 0.05, vs. sham group. * p < 0.05, vs. burn group. # p < 0.05, vs. commensal depletion + burn group. (B) Commensal depletion induced a significant increase of bacterial retention of peritoneal cells in burn mice compared with that of burn group. LPS supplement significantly decreased 55% of bacterial retention compared with that of antibiotics + burn group. * p < 0.05, vs. burn group. # p < 0.05, vs. commensal depletion + burn group.