Role of host glutaminolysis in tuberculosis pathogenesis

Louisiana State Univ A&M Col Baton Rouge, Baton Rouge LA

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Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains the leading infectious disease, causing an estimated 1.25 million deaths worldwide in 2023. Current treatment regimens are long and toxic, contributing to poor adherence, adverse effects, and suboptimal outcomes. Hence, there is an urgent need for host-directed therapies that can shorten treatment duration and reduce systemic toxicity. Mtb primarily infects the lungs and replicates within macrophages, subverting host immunity. Recent studies strongly suggest that host glutamine metabolism may support Mtb survival, making it a promising therapeutic target. It is known that Mtb-infected macrophages upregulate g/s1, the gene encoding glutaminase (GLS1), which catalyzes the conversion of glutamine to glutamate. Our preliminary data suggest that pharmacological inhibition with JHU083, a pleiotropic glutamine metabolism antagonist, downregulates g/s1 expression in macrophages and decreases Mtb bacillary burden. Mtb-infected mice, when treated with JHU083, exhibit reduced lung bacillary burden, elevated host immune response and improved survival. Additionally, we showed that pharmacological inhibition of GLS1 improves the phagocytic activity of macrophages. This proposal aims to test the central hypothesis that inhibition of host glutaminolysis will restore the antimycobacterial activity of Mtb-infected macrophages. Aim 1 will evaluate whether host glutaminolysis inhibition restores the antimycobacterial activity of Mtbinfected macrophages. First, we will generate macrophages deficient in GLS1 using siRNA knockdown, chemical inhibition or macrophage-specific GLS1 knockout mouse (macGLS1-KO). We will then assess the impact of GLS1 deficiency upon the antimycobacterial activity of macrophages by measuring several parameters including intracellular bacterial burden, phagocytosis, oxidative burst, proinflammatory response, apoptosis, and metabolic changes. Aim 2 will investigate whether macrophage-specific glutaminolysis inhibition improves Mtb clearance in the mouse lungs. To do so, we will infect macGLS1-KO mice with Mtb and assess the impact of GLS1 deficiency upon disease progression by measuring several parameters including bacterial load in their lungs, survival, lung pathology, immune responses, and metabolic changes. Together, these aims will define the role of GLS1 in TB pathogenesis and establish its potential as a hostdirected therapeutic target. The proposal heavily relies on the expertise of CoBRE Infection & Inhalation, and Pulmonary lmmunopathology cores in order to generate key data for future NIH and extramural grant applications.