Figure 2. Impact of NLRP6 on survival, bacterial clearance, cellular recruitment, and cytokine/chemokine production during Kp infection.

(A) Nlrp6^−/− and WT mice were infected with 10³ or 10⁴ CFU of Kp and survival was recorded for 15 days. A Kaplan-Meier plot is used to show survival of mice from each group. (n=20/group). Statistical significance was determined by log-rank. (B–K) Nlrp6^−/− and WT mice were infected with 10³ CFU of Kp and BALF and organs were harvested at 24 and 48 h post-infection. Bacterial burden in lungs (B) and spleen (C) was assessed at the indicated time points (n=6/group). Total number of white blood cells (D), neutrophils (E) in BALF, and MPO activity in lung homogenates (F) were measured at 24 and 48 h post-infection (n=3/group). (G–H) Lungs from Kp-infected mice were perfused and processed for histology, stained with H&E, and inflammatory changes in histological sections were scored. (G) Representative histological mouse lung sections are presented. (H) Inflammation score obtained by semiquantitative histology are shown at 24 and 48 h post-infection (n=5/group). Original magnification, 40X. (I–K) Levels of neutrophil-attracting chemokines CXCL1 (I), CXCL2 (J), and CXCL5 (K) in BALF were measured at 24 and 48 h post-infection (n=3/group). (L–N) Nlrp6^−/− or Nlrp3^−/− on the A/J background mice were inoculated with Kp (10³ CFU/mouse) and BALF and organs were harvested at 24 and 48 h post-infection. Bacterial burden in lungs (L), spleens (M), and neutrophils (N) in BALF were enumerated at 24 and 48 h post-infection (n=5/group). (O, P) Bone marrow chimeric mice were generated and infected with Kp (10³ CFU/mouse). At 48 h post-infection, the bacterial burden was assessed in the lungs (O) and spleens (P). (n = 4–6/infection group). Unpaired t-test (B–F, H–K), and ANOVA (followed by Tukey’s multiple comparisons) (L–P). *, p<0.05; **, p<0.01; ***, p<0.001. WBC: White blood cells, MPO: Myeloperoxidase.