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The TLR4 Agonist Monophosphoryl Lipid A Drives Broad Resistance to Infection via Dynamic Reprogramming of Macrophage Metabolism.

ABSTRACT: Monophosphoryl lipid A (MPLA) is a clinically used TLR4 agonist that has been found to drive nonspecific resistance to infection for up to 2 wk. However, the molecular mechanisms conferring protection are not well understood. In this study, we found that MPLA prompts resistance to infection, in part, by inducing a sustained and dynamic metabolic program in macrophages that supports improved pathogen clearance. Mice treated with MPLA had enhanced resistance to infection with Staphylococcus aureus and Candida albicans that was associated with augmented microbial clearance and organ protection. Tissue macrophages, which exhibited augmented phagocytosis and respiratory burst after MPLA treatment, were required for the beneficial effects of MPLA. Further analysis of the macrophage phenotype revealed that early TLR4-driven aerobic glycolysis was later coupled with mitochondrial biogenesis, enhanced malate shuttling, and increased mitochondrial ATP production. This metabolic program was initiated by overlapping and redundant contributions of MyD88- and TRIF-dependent signaling pathways as well as downstream mTOR activation. Blockade of mTOR signaling inhibited the development of the metabolic and functional macrophage phenotype and ablated MPLA-induced resistance to infection in vivo. Our findings reveal that MPLA drives macrophage metabolic reprogramming that evolves over a period of days to support a macrophage phenotype highly effective at mediating microbe clearance and that this results in nonspecific resistance to infection.

SUBMITTER: Fensterheim BA

PROVIDER: S-EPMC5964009 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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The TLR4 Agonist Monophosphoryl Lipid A Drives Broad Resistance to Infection via Dynamic Reprogramming of Macrophage Metabolism.

Fensterheim Benjamin A BA Young Jamey D JD Luan Liming L Kleinbard Ruby R RR Stothers Cody L CL Patil Naeem K NK McAtee-Pereira Allison G AG Guo Yin Y Trenary Irina I Hernandez Antonio A Fults Jessica B JB Williams David L DL Sherwood Edward R ER Bohannon Julia K JK

Journal of immunology (Baltimore, Md. : 1950) 20180423 11

Monophosphoryl lipid A (MPLA) is a clinically used TLR4 agonist that has been found to drive nonspecific resistance to infection for up to 2 wk. However, the molecular mechanisms conferring protection are not well understood. In this study, we found that MPLA prompts resistance to infection, in part, by inducing a sustained and dynamic metabolic program in macrophages that supports improved pathogen clearance. Mice treated with MPLA had enhanced resistance to infection with <i>Staphylococcus aur ...[more]

PMID: 29686054

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Project description:RATIONALE:A hallmark of chronic inflammatory disorders is persistence of proinflammatory macrophages in diseased tissues. In atherosclerosis, this is associated with dyslipidemia and oxidative stress, but mechanisms linking these phenomena to macrophage activation remain incompletely understood. OBJECTIVE:To investigate mechanisms linking dyslipidemia, oxidative stress, and macrophage activation through modulation of immunometabolism and to explore therapeutic potential targeting specific metabolic pathways. METHODS AND RESULTS:Using a combination of biochemical, immunologic, and ex vivo cell metabolic studies, we report that CD36 mediates a mitochondrial metabolic switch from oxidative phosphorylation to superoxide production in response to its ligand, oxidized LDL (low-density lipoprotein). Mitochondrial-specific inhibition of superoxide inhibited oxidized LDL-induced NF-?B (nuclear factor-?B) activation and inflammatory cytokine generation. RNA sequencing, flow cytometry, 3H-labeled palmitic acid uptake, lipidomic analysis, confocal and electron microscopy imaging, and functional energetics revealed that oxidized LDL upregulated effectors of long-chain fatty acid uptake and mitochondrial import, while downregulating fatty acid oxidation and inhibiting ATP5A (ATP synthase F1 subunit alpha)-an electron transport chain component. The combined effect is long-chain fatty acid accumulation, alteration of mitochondrial structure and function, repurposing of the electron transport chain to superoxide production, and NF-?B activation. Apoe null mice challenged with high-fat diet showed similar metabolic changes in circulating Ly6C+ monocytes and peritoneal macrophages, along with increased CD36 expression. Moreover, mitochondrial reactive oxygen species were positively correlated with CD36 expression in aortic lesional macrophages. CONCLUSIONS:These findings reveal that oxidized LDL/CD36 signaling in macrophages links dysregulated fatty acid metabolism to oxidative stress from the mitochondria, which drives chronic inflammation. Thus, targeting to CD36 and its downstream effectors may serve as potential new strategies against chronic inflammatory diseases such as atherosclerosis.

Dataset Information

The TLR4 Agonist Monophosphoryl Lipid A Drives Broad Resistance to Infection via Dynamic Reprogramming of Macrophage Metabolism.

Publications

The TLR4 Agonist Monophosphoryl Lipid A Drives Broad Resistance to Infection via Dynamic Reprogramming of Macrophage Metabolism.

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