Figure 9.
Capsule type-dependent evasion of hepatic clearance of invasive E. coli. (A) Capsule type-dependent virulence of invasive E. coli isolates. Survival (left) and bacteremia (right) levels of mice i.p. infected with 107 CFU of unencapsulated mutant (Δcps), representative HV (K1 and K5), and LV (K2ab and KG2-1) isogenic E. coli in type K1 TH14515 background. n = 5. (B) Capsule type-dependent clearance of isogenic E. coli strains in the blood. Bacteremia kinetics (left) and calculated clearance rate (right) were measured during the first 30 min after i.v. infection with 107 CFU of isogenic E. coli. n = 3–6. (C) Proportional distribution of isogenic E. coli strains in the blood, liver, and spleen of mice in the first 30 min after infection as in B. n = 3–6. (D) Importance of KC, monocytes, and neutrophils in early clearance of LV type K2ab E. coli. Mice were treated for specific depletion as in Fig. 5 B before i.v. infection with 107 CFU of TH15511K2ab and bled for enumeration of viable bacteria in the blood (left). The clearance rates (right) were calculated as in Fig. 4 F. n = 3–5. (E) Proportional distribution of E. coli TH15511K2ab in the blood, liver, and spleen of mice in the first 30 min after infection. n = 3–5. (F) Capsule type-dependent evasion of KC capture by E. coli. Representative IVM images (left) of the liver sinusoids in the mice infected i.v. with 5 × 107 CFU of FITC-labeled isogenic E. coli strains (n = 2). The imaging data were quantified in the right panel (n = 5–10 random fields). Scale bar, 20 μm. (G) Inhibition of free CPSs to the early clearance of the homologous LV E. coli strains. Bacterial load in the blood were measured in the mice pretreated with control PBS or 400 μg of each CPS 2 min before i.v. infection with 107 CFU of LV bacteria. n = 3–5. (H) Proportional distribution of E. coli in the blood, liver, and spleen of mice in the first 30 min after infection as in G. n = 3–5. (I) Cross-inhibition of E. coli capsules to the early clearance of heterologous strains. Bacterial load in the blood was measured in the mice pretreated with 400 μg of each CPS 2 min before i.v. infection with 107 CFU of E. coli TH15511K2ab. n = 3. (J) Proportional distribution of E. coli in the blood, liver, and spleen of mice in the first 30 min after infection as in I. n = 3. (K) Visualization of inhibitory effect of LV CPSs on KC capture of E. coli. Representative IVM images (left) display significantly reduced LV E. coli captured by KCs after administration with homologous but not heterologous CPSs (n = 2). The imaging data were quantified in the right panel (n = 5–10 random fields). Scale bar, 20 μm. All mice were used in C57BL/6 background. Data were representative results (F and K) or pooled (A–E and G–J) from two independent experiments. Ordinary one-way ANOVA with Dunnett’s (B and F) or Tukey’s (D, right panel, and K) multiple comparisons test, two-way ANOVA with Tukey’s multiple comparisons test (D, left panel, and I), **, P < 0.01, ***, P < 0.001, ****, P < 0.0001.

Capsule type-dependent evasion of hepatic clearance of invasive E. coli. (A) Capsule type-dependent virulence of invasive E. coli isolates. Survival (left) and bacteremia (right) levels of mice i.p. infected with 107 CFU of unencapsulated mutant (Δcps), representative HV (K1 and K5), and LV (K2ab and KG2-1) isogenic E. coli in type K1 TH14515 background. n = 5. (B) Capsule type-dependent clearance of isogenic E. coli strains in the blood. Bacteremia kinetics (left) and calculated clearance rate (right) were measured during the first 30 min after i.v. infection with 107 CFU of isogenic E. coli. n = 3–6. (C) Proportional distribution of isogenic E. coli strains in the blood, liver, and spleen of mice in the first 30 min after infection as in B. n = 3–6. (D) Importance of KC, monocytes, and neutrophils in early clearance of LV type K2ab E. coli. Mice were treated for specific depletion as in Fig. 5 B before i.v. infection with 107 CFU of TH15511K2ab and bled for enumeration of viable bacteria in the blood (left). The clearance rates (right) were calculated as in Fig. 4 F. n = 3–5. (E) Proportional distribution of E. coli TH15511K2ab in the blood, liver, and spleen of mice in the first 30 min after infection. n = 3–5. (F) Capsule type-dependent evasion of KC capture by E. coli. Representative IVM images (left) of the liver sinusoids in the mice infected i.v. with 5 × 107 CFU of FITC-labeled isogenic E. coli strains (n = 2). The imaging data were quantified in the right panel (n = 5–10 random fields). Scale bar, 20 μm. (G) Inhibition of free CPSs to the early clearance of the homologous LV E. coli strains. Bacterial load in the blood were measured in the mice pretreated with control PBS or 400 μg of each CPS 2 min before i.v. infection with 107 CFU of LV bacteria. n = 3–5. (H) Proportional distribution of E. coli in the blood, liver, and spleen of mice in the first 30 min after infection as in G. n = 3–5. (I) Cross-inhibition of E. coli capsules to the early clearance of heterologous strains. Bacterial load in the blood was measured in the mice pretreated with 400 μg of each CPS 2 min before i.v. infection with 107 CFU of E. coli TH15511K2ab. n = 3. (J) Proportional distribution of E. coli in the blood, liver, and spleen of mice in the first 30 min after infection as in I. n = 3. (K) Visualization of inhibitory effect of LV CPSs on KC capture of E. coli. Representative IVM images (left) display significantly reduced LV E. coli captured by KCs after administration with homologous but not heterologous CPSs (n = 2). The imaging data were quantified in the right panel (n = 5–10 random fields). Scale bar, 20 μm. All mice were used in C57BL/6 background. Data were representative results (F and K) or pooled (A–E and G–J) from two independent experiments. Ordinary one-way ANOVA with Dunnett’s (B and F) or Tukey’s (D, right panel, and K) multiple comparisons test, two-way ANOVA with Tukey’s multiple comparisons test (D, left panel, and I), **, P < 0.01, ***, P < 0.001, ****, P < 0.0001.

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