Host immunology and rational immunotherapy for carbapenem-resistant Klebsiella pneumoniae infection
Naoki Iwanaga, Ivy Sandquist, Alanna Wanek, Janet McCombs, Kejing Song, Jay K. Kolls
Naoki Iwanaga, Ivy Sandquist, Alanna Wanek, Janet McCombs, Kejing Song, Jay K. Kolls
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Research Article Infectious disease Pulmonology

Host immunology and rational immunotherapy for carbapenem-resistant Klebsiella pneumoniae infection

Abstract

Infections due to carbapenem-resistant Klebsiella pneumoniae have emerged as a global threat due to its widespread antimicrobial resistance. Transplant recipients and patients with hematologic malignancies have high mortality rate, suggesting host factors in susceptibility. We developed a model of pulmonary infection using ST258 strain C4, KPC-2 clone, which are predominant K. pneumoniae carbapenemase–producing (KPC-producing) bacteria, and demonstrated that Rag2–/– Il2rg–/– mice — but not WT C57BL/6 or Rag2–/– mice — were susceptible to this opportunistic infection. Using single cell RNA sequencing in infected Rag2–/– mice, we identified distinct clusters of Ifng+ NK cells and Il17a+, Il22+, and inducible T cell costimulatory molecule–positive (ICOS+) group 3 innate lymphoid cells (ILCs) that were critical for host resistance. As solid organ transplantation is a risk factor, we generated a more clinically relevant model using FK506 in WT C57BL/6 mice. We further demonstrated that immunotherapy with recombinant IL-22 treatment ameliorated the ST258 pulmonary infection in both FK506-treated WT mice and Rag2–/– Il2rg–/– mice via hepatic IL-22ra1 signaling. These data support the development of host-directed immunotherapy as an adjunct treatment to new antibiotics.

Authors

Naoki Iwanaga, Ivy Sandquist, Alanna Wanek, Janet McCombs, Kejing Song, Jay K. Kolls

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Figure 6

Pharmacological model of host KPC susceptibility with FK506 mimics the susceptibility in Rag2–/– Il2rg–/– mice.

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Pharmacological model of host KPC susceptibility with FK506 mimics the s...
Six- to 8-week-old male C57BL/6 mice were treated with vehicle control or 10 mg/kg FK506 i.p. 24 hours prior to intratracheal challenge with 1 × 106 ST258 C4 strain. FK506 was administered every 24 hours until 24 hours before euthanasia. Lungs were harvested 48 hours after infection. (A–E, N, and O) Il17a (A), Il17f (B), Il22 (C), Ifng (D), Klrb1c (N), and Tcrg (O) mRNA expression, and CFU in the lungs (E) of naive C57BL/6, infected C57BL/6, and infected C57BL/6 mice treated with FK506 are shown (n=4, two independent experiments). Expression of mRNA was normalized to the constitutive expression of Hprt mRNA, and data are presented as mean ± SEM. (L and M) The absolute number of lung NK cells (L) and lung γδ cells (M) were also examined by FACS 24 hours after pulmonary challenge in 6- to 8-week-old male C57BL/6 mice treated with vehicle control or FK506. Data are presented as mean ± SEM (n=5, two independent experiments). Significant differences are designated by using 1-way ANOVA test followed by Tukey’s multiple comparisons test. *P < 0.05, ***P < 0.001, ****P < 0.0001. CFU was compared by using Mann-Whitney U test. ***P < 0.001 versus vehicle control. Six- to 8-week-old male FK506-treated WT C57BL/6 mice were infected with 1 × 106 CFU ST258 C4 strain intratracheally; 24 hours after inoculation, lungs were harvested to analyze single cell RNA sequencing. A total of 10 mg/kg FK506 was administered i.p. 24 hours prior to intratracheal challenge and every 24 hours until 24 hours before euthanasia. (F–K) The violin plots from Seurat of scRNAseq data showed FK506 treatment affected to reduce various cytokine gene expression such as Il17a (F), Il17f (G), Il22 (H), Ifng (I), but not Klrb1c (J) and Tcrg (K).