ABSTRACT
Obesity impairs host defense against Klebsiella pneumoniae, but responsible mechanisms are incompletely understood. To determine the impact of diet-induced obesity on pulmonary host defense against K. pneumoniae, we fed 6-wk-old male C57BL/6j mice a normal diet (ND) or high-fat diet (HFD) (13% vs. 60% fat, respectively) for 16 wk. Mice were intratracheally infected with Klebsiella, assayed at 24 or 48 h for bacterial colony-forming units, lung cytokines, and leukocytes from alveolar spaces, lung parenchyma, and gonadal adipose tissue were assessed using flow cytometry. Neutrophils from uninfected mice were cultured with and without 2-deoxy-d-glucose (2-DG) and assessed for phagocytosis, killing, reactive oxygen intermediates (ROI), transport of 2-DG, and glucose transporter (GLUT1-4) transcripts, and protein expression of GLUT1 and GLUT3. HFD mice had higher lung and splenic bacterial burdens. In HFD mice, baseline lung homogenate concentrations of IL-1ß, IL-6, IL-17, IFN-γ, CXCL2, and TNF-α were reduced relative to ND mice, but following infection were greater for IL-6, CCL2, CXCL2, and IL-1ß (24 h only). Despite equivalent lung homogenate leukocytes, HFD mice had fewer intraalveolar neutrophils. HFD neutrophils exhibited decreased Klebsiella phagocytosis and killing and reduced ROI to heat-killed Klebsiella in vitro. 2-DG transport was lower in HFD neutrophils, with reduced GLUT1 and GLUT3 transcripts and protein (GLUT3 only). Blocking glycolysis with 2-DG impaired bacterial killing and ROI production in neutrophils from mice fed ND but not HFD. Diet-induced obesity impairs pulmonary Klebsiella clearance and augments blood dissemination by reducing neutrophil killing and ROI due to impaired glucose transport.
Subject(s)
Diet , Glucose/metabolism , Host-Pathogen Interactions , Klebsiella Infections/microbiology , Klebsiella pneumoniae/physiology , Neutrophils/metabolism , Obesity/microbiology , Adipose Tissue, White/drug effects , Adipose Tissue, White/metabolism , Adiposity/drug effects , Animals , Bacterial Load/drug effects , Biological Transport/drug effects , Blood Glucose/metabolism , Body Weight/drug effects , Bone Marrow/pathology , Bronchoalveolar Lavage Fluid/cytology , Cytokines/metabolism , Deoxyglucose/pharmacology , Diet, High-Fat , Glucose Transporter Type 1/genetics , Glucose Transporter Type 1/metabolism , Glucose Transporter Type 3/genetics , Glucose Transporter Type 3/metabolism , Glycolysis/drug effects , Host-Pathogen Interactions/drug effects , Klebsiella Infections/blood , Klebsiella Infections/complications , Klebsiella pneumoniae/drug effects , Leukocyte Count , Lung/microbiology , Lung/pathology , Male , Mice, Inbred C57BL , Neutrophils/drug effects , Obesity/blood , Obesity/complications , Phagocytosis/drug effects , Pneumonia/microbiology , Pneumonia/pathology , RNA, Messenger/genetics , RNA, Messenger/metabolism , Spleen/microbiologyABSTRACT
AIM: High-dose valproic acid (VPA) improves the survival and neurologic outcomes after asphyxial cardiac arrest (CA) in rats. We characterized the pharmacokinetics, pharmacodynamics, and safety of high-dose VPA in a swine CA model to advance clinical translation. METHODS: After 8 âmin of untreated ventricular fibrillation CA, 20 male Yorkshire swine were resuscitated until return of spontaneous circulation (ROSC). They were block randomized to receive placebo, 75 âmg/kg, 150 âmg/kg, or 300 âmg/kg VPA as 90-min intravenous infusion (n â= â5/group) beginning at ROSC. Animals were monitored for 2 additional hours then euthanized. Experimental operators were blinded to treatments. RESULTS: The mean(SD) total CA duration was 14.8(1.2) minutes. 300 âmg/kg VPA animals required more adrenaline to maintain mean arterial pressure ≥80 âmmHg and had worse lactic acidosis. There was a strong linear correlation between plasma free VPA Cmax and brain total VPA (r2 â= â0.9494; p â< â0.0001). VPA induced dose-dependent increases in pan- and site-specific histone H3 and H4 acetylation in the brain. Plasma free VPA Cmax is a better predictor than peripheral blood mononuclear cell histone acetylation for brain H3 and H4 acetylation (r2 â= â0.7189 for H3K27ac, r2 â= â0.7189 for pan-H3ac, and r2 â= â0.7554 for pan-H4ac; p â< â0.0001). CONCLUSIONS: Up to 150 âmg/kg VPA can be safely tolerated as 90-min intravenous infusion in a swine CA model. High-dose VPA induced dose-dependent increases in brain histone H3 and H4 acetylation, which can be predicted by plasma free VPA Cmax as the pharmacodynamics biomarker for VPA target engagement after CA.