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Biology subjects

Dawa, S.

Publications and source records attributed to Dawa, S..

4 recordsLinked to original sources

Title: Multimodal profiling reveals Mycobacterium tuberculosis restricts lung mitochondrial immunometabolism to promote pathogenesis

Early events in the lung that shape protective immune responses to M. tuberculosis (Mtb) infection are not well understood but are critical for developing better vaccines and immunomodulatory therapies for tuberculosis. Here, we used high-dimensional flow cytometry, single-cell transcriptomics, and untargeted metabolomics to define the early lung immune environment that precedes the development of protective versus pathogenic outcomes following aerosolized Mtb infection of mice. We show that Mtb induced sustained glycolysis in the lung while restricting oxidative phosphorylation (OXPHOS) and impairing mitochondria, in part through the Mtb serine protease Hip1, leading to low energy output and suboptimal macrophage-T cell interactions that promoted pathogenic immunity. However, robust induction of mitochondrial OXPHOS, amino acid metabolism, and fatty acid oxidation in the early lung resulted in high ATP output and enhanced innate-T cell signaling networks that stimulated protective immune responses. Moreover, we identified a novel mitochondrial immunometabolic lung signature associated with protective outcomes to Mtb infection in animal models and humans. Our studies identify induction of mitochondrial dysfunction as a mechanism employed by Mtb to manipulate lung immunometabolism to its benefit and reveal that maintenance of intact mitochondrial metabolism in the early lung is pivotal for generating protective outcomes to Mtb infection.

immunology↗

Inhibition of granuloma triglyceride synthesis imparts control of Mycobacterium tuberculosis through curtailed inflammatory responses

Lipid metabolism plays a complex and dynamic role in host-pathogen interaction during Mycobacterium tuberculosis infection. While bacterial lipid metabolism is key to the success of the pathogen, the host also offers a lipid rich environment in the form of necrotic caseous granulomas, making this association beneficial for the pathogen. Accumulation of the neutral lipid triglyceride, as lipid droplets at the cellular cuff of necrotic granulomas, is a peculiar feature of pulmonary tuberculosis. The role of triglyceride synthesis in the TB granuloma and its impact on the disease outcome has not been studied in detail. Here, we identified diacylglycerol O-acyltransferase 1 (DGAT1) to be essential for accumulation of triglyceride in necrotic TB granulomas using the C3HeB/FeJ murine model of infection. Treatment of infected mice with a pharmacological inhibitor of DGAT1 (T863) led to reduction in granuloma triglyceride levels and bacterial burden. A decrease in bacterial burden was associated with reduced neutrophil infiltration and degranulation, and a reduction in several pro-inflammatory cytokines including IL1{beta}, TNF, IL6, and IFN{beta}. Triglyceride lowering impacted eicosanoid production through both metabolic re-routing and via transcriptional control. Our data suggests that manipulation of lipid droplet homeostasis may offer a means for host directed therapy in Tuberculosis.

immunology↗

The antidepressant sertraline provides a novel host directed therapy module for augmenting TB therapy

A prolonged therapy, primarily responsible for development of drug resistance by Mycobacterium tuberculosis (Mtb), obligates any new TB regimen to not only reduce treatment duration but also escape pathogen resistance mechanisms. With the aim of harnessing the host response in providing support to existing regimens, we used sertraline (SRT) to stunt the pro-pathogenic type I IFN response of macrophages to infection. While SRT alone could only arrest bacterial growth, it effectively escalated the bactericidal activities of Isoniazid (H) and Rifampicin (R) in macrophages. This strengthening of antibiotic potencies by SRT was more evident in conditions of ineffective control by these frontline TB drug, against tolerant strains or dormant Mtb. SRT, could significantly combine with standard TB drugs to enhance early pathogen clearance from tissues of mice infected with either drug sensitive/ tolerant strains of Mtb. Further, we demonstrate an enhanced protection in acute TB infection of the highly susceptible C3HeB/FeJ mice with the combination therapy signifying the use of SRT as a potent adjunct to standard TB therapeutic regimens against bacterial populations of diverse physiology. This study advocates a novel host directed adjunct therapy regimen for TB with a clinically approved anti-depressant to achieve quicker and greater control of infection.

immunology↗

Necrosis triggered by Mycobacterium tuberculosis alters macrophage triglyceride metabolism and inflammatory response in a DGAT1-dependent manner

Tuberculosis granulomas represent a site of controlling bacterial dissemination at the cost of host tissue damage. Within the heterogenous array of TB granulomas, some contain triglyceride (TG) rich foamy macrophages, the etiology and function of which remains largely unexplained. Here we show that necrosis of tuberculosis lesions and M. tuberculosis (Mtb) infected macrophages elicits a bystander response of triglyceride storage. We elucidate a role for the RD1 region of mycobacterial genome to be a key player in this phenomenon. TG storage in necrosis associated foamy macrophages promoted the pro-inflammatory state of macrophages while silencing expression of diacylglycerol O-acyltransferase (DGAT1) suppressed expression of pro-inflammatory genes. Surprisingly, acute infection with Mtb led to lipolysis of host TG, rather than synthesis, suggesting mobilization of triglyceride stored within macrophage lipid droplets to be involved in the inflammatory response to infection. Our data is likely to open new avenues for management of the inflammatory response during infection.

immunology↗