Fig. 6: ArgR is required for K. pneumoniae to evade immortalized bone marrow-derived macrophages (iBMDMs) association and maintain competitive fitness in the lung.
From: Arginine regulates the mucoid phenotype of hypervirulent Klebsiella pneumoniae
A Macrophages (BEI NR-9456) were incubated with KPPR1 or ∆argR for 2 hr (MOI = 10). Internalization was determined by a 1 hr gentamicin treatment. Macrophages were washed with PBS, lysed with 0.2% TritonX100, and output CFUs were enumerated and normalized to input. Experiments were performed > 3 independent times, in triplicate (n = 9). Data presented are the mean, and error bars represent the standard error of the mean. B C57BL/6 mice were infected retropharyngeally with 1 × 106 CFUs of a 1:1 mixture of WT + EV and either ∆argR + EV or ∆argR + pargR. The log10 competitive index at 24 h post-infection is shown relative to 0. Each dot represents an individual mouse (open symbols = male; half-filled = female). The horizontal line represents the median; box bounds indicate the minima (25TH percentile) and maxima (75TH percentile); and whiskers represent the full range. ∆argR + EV was tested in two independent experiments (n = 8), while ∆argR+pargR was tested once (n = 7). C Arginine concentrations were measured in murine lungs, spleens, livers, and feces. Samples were collected from three mice and experiments were performed 3 independent times, in technical triplicate (n = 3). Data presented are the mean, and error bars represent the standard error of the mean. Statistical significance was determined using an unpaired two-tailed t-test (A), a two-tailed unpaired t-test (B, comparing CI values between ∆argR + EV and ∆argR+pargR), and a two-tailed one-sample t-test (B, comparing CI to a hypothetical value of zero). In (C), a one-way ANOVA with Tukey’s post-test was used. p-values are displayed above each comparison; *p < 0.05; **p < 0.01, ***p < 0.001; #p < 0.0001. Exact P-values: (A) left to right: <0.0001, 0.0287; (B) left to right above data bars: 0.0008, 0.0078, 0.0081; connected by lines: <0.0001; (C) left to right: 0.0033, <0.0001, 0.0327, 0.0003. Source data are provided as a Source Data file.
