Biophysical Society Thematic Meeting - November 16-20, 2015

Biophysics in the Understanding, Diagnosis, and Treatment of Infectious Diseases Poster Abstracts

27-POS Board 27 Directing Warburg: Mycobacterium Tuberculosis Redirects Host Energy Metabolism in the TB Lung James Hove Mazorodze 1 , Bridgette Cumming 1 , Shannon Russell 1 , Jun Li 2 , Vikram Saini 2 , Anna Moshnikova 3 , Yana Reshetnyak 3 , Oleg Andreev 3 , Joel Glasgow 2 , Adrie Steyn 1,2 . 1 K-RITH, Durban, KwaZulu Natal, South Africa, 2 University of Alabama at Birmingham, Birmingham, AL, USA, 3 University of Rhode Island, Rhode Island, RI, USA. The physiological consequences of hypoxia and acidosis in Mycobacterium tuberculosis (Mtb) infection are poorly understood. We hypothesized that Mtb redirects host metabolism from oxidative phosphorylation towards increased aerobic glycolysis (the “Warburg Effect”) resulting in elevated lactate levels and extracellular acidity. To test this hypothesis, we used extracellular flux analysis with an XF96 machine that measures oxygen consumption rate, as a measure of oxidative phosphorylation and extracellular acidification rate as a measure of glycolysis. Mtb infection induced a shift from oxidative phosphorylation to aerobic glycolysis. This shift induced extracellular acidity as demonstrated using a fluorescently labelled pH (low) insertion peptide (pHLIP). Mtb-infected mice were injected with fluorescently labelled pHLIP peptides and the lungs examined ex vivo using near-infrared fluorescence (NIRF) imaging. Immunohistochemistry was performed using antibodies against GLUT1 (a glucose transporter), HIF-1α (hypoxia inducible factor), MCT4 (monocarboxylate transporter 4), LDHA (lactate dehydrogenase A) and NHE1 (sodium hydrogen exporter 1). We used a metabolomics approach to quantify intermediates of the glycolytic and tricarboxylic acid (TCA) cycle in Mtb-infected and uninfected mice. Lastly, we measured differential expression of select genes involved in glycolysis, TCA cycle, acidosis and hypoxia. We observed significantly increased fluorescence intensity in lesions of Mtb-infected lungs compared to uninfected mice via NIRF imaging. Immunostaining revealed increased levels of GLUT1, LDHA, MCT4, NHE1 and HIF-1α in Mtb- infected vs uninfected mice. Further, select genes involved in glycolysis, TCA cycle, acidosis and hypoxia were upregulated in Mtb-infected mice, consistent with immunohistochemistry and pHLIP NIRF imaging. We conclude that Mtb results in a shift from host oxidative phosphorylation to glycolysis, resulting in acidic extracellular pH changes due to accumulation of lactate.

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