Chemokine (C-X-C motif) ligand 4 (CXCL4) deficiency impairs bacterial clearance and airway epithelial permeability after <i>P</i>. <i>aeruginosa</i> lung infection.

(A, B, C, D) CXCL4 deficiency results in impaired bacterial clearance following P. aeruginosa lung infection but it does not affect host mortality and morbidity. Wild-type and CXCL4-/- mice were intranasally infected with 1×109 CFU of P. aeruginosa strain 8821 for 24 h. BALF and lungs were collected at 24 hpi. Serial dilutions of homogenized BALF and lung tissue were streaked onto LB agar plates and incubated 24 h at 37°C. The resulting colonies were counted to determine bacteria load (n = 9 ± SEM, *p -/- mice were intranasally infected with 1×109 CFU of P. aeruginosa strain 8821. Animal survival and body weight were monitored up to 7 days post infection (n = 12 ± SEM). (E, F) CXCL4-deficient mice display increased airway epithelial permeability after P. aeruginosa infection. Wild-type and CXCL4-/- mice were left uninfected (NT) or intranasally infected with 1×109 CFU of P. aeruginosa strain 8821. Six hours after infection, the mice received intraperitoneal injections of Evans blue dye. Blood, lungs and BALF were collected at 24 hpi. Dye leakage into the BALF and lungs was assessed and is presented as the OD620 ratio to a 1:20 dilution of serum (n = 4 ± SEM, **p < 0.01).