Increased Neutrophil H2O2 Production and Enhanced Pulmonary Clearance of Klebsiella pneumoniae in G6PD A- Mice

Abstract

The X-linked A^- variant (rs1050828, Val68Met) in G6PDX accounts for glucose-6-phosphate (G6PD) deficiency in approximately 11% of African American males. This common, hypomorphic variant may impact pulmonary host defense and phagocyte function during pneumonia by altering levels of reactive oxygen species produced by host leukocytes. We used CRISPR-Cas9 technology to generate novel mouse strain with “humanized” G6PD A- variant containing non-synonymous Val68Met single nucleotide polymorphism. Male hemizygous or littermate wild-type (WT) controls were inoculated intratracheally with K. pneumoniae (KP2 serotype, ATCC 43816 strain,10³ CFU inoculum). We examined leukocyte recruitment, organ bacterial burden, bone marrow neutrophil and macrophage (BMDM) phagocytic capacity, and hydrogen peroxide (H₂O₂) production. Unexpectedly, G6PD-deficient mice showed decreased lung bacterial burden (p=0.05) compared to controls 24-h post-infection. Extrapulmonary dissemination and bacteremia were significantly reduced in G6PD-deficient mice 48-h post-infection. Bronchoalveolar lavage fluid (BALF) IL-10 levels were elevated in G6PD-deficient mice (p=0.03) compared to controls at 24-h but were lower at 48-h (p=0.03). G6PD A- BMDMs show mildly decreased in vitro phagocytosis of pHrodo-labeled KP2 (p=0.03). Baseline, but not stimulated, H₂O₂ production by G6PD A- neutrophils was greater compared to WT neutrophils. G6PD A- variant demonstrate higher basal neutrophil H₂O₂ production and are protected against acute Klebsiella intrapulmonary infection.