Fig. 4.

MTV increases PMN infiltration in lungs of septic mice. Neutrophil immigration in lung detected by flow cytometry. Mice receiving combination of CLP + MTV (two-hit model) compared to mice subjected to CLP alone for 18 h or sham operation followed by 6 h of MTV. Two-hit model in wildtype mice compared to subgroup of TLR4 null mice or wildtype mice that received intratracheally neutralizing antibodies to either integrin β5 (β5 Ab) or WISP1 (WISP1 Ab) (or control antibodies (IgG Ab)). Neutrophil influx by quantifying percent of CD11b⁺ and Ly6G⁺ cells in CD45⁺ cell population isolated from lung homogenates. CLP significantly increased percent of PMN while MTV had no impact on percent PMN in lung; CLP and MTV (two-hit model) significantly further increased neutrophil immigration in lung whereas TLR4 deletion completely prevented change in percentage of PMN induced by CLP + MTV compared to this two-hit model in wildtype mice. Blocking either WISP1 or integrin β5 partially prevented increase in percentage of PMN induced in two-hit model compared to combined CLP and MTV in mice receiving control IgG antibody. *P < 0.05; **P < 0.01; ***P < 0.001. CLP cecal ligation and puncture, MTV moderate tidal ventilation, TLR4 toll-like receptor 4, WISP1 WNT1 inducible secreted protein