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Acetate sensing by GPR43 alarms neutrophils and protects from severe sepsis.

ABSTRACT: Bacterial sepsis is a major cause of mortality resulting from inadequate immune responses to systemic infection. Effective immunomodulatory approaches are urgently needed but it has remained elusive, which targets might be suitable for intervention. Increased expression of the G-protein-coupled receptor GPR43, which is known to govern intestinal responses to acetate, has been associated with sepsis patient survival but the mechanisms behind this observation have remained unclear. We show that elevated serum acetate concentrations prime neutrophils in a GPR43-dependent fashion, leading to enhanced neutrophil chemotaxis, oxidative burst, cytokine release and upregulation of phagocytic receptors. Consequently, acetate priming improved the capacity of human neutrophils to eliminate methicillin-resistant Staphylococcus aureus. Acetate administration increased mouse serum acetate concentrations and primed neutrophils. Notably, it rescued wild-type mice from severe S. aureus sepsis and reduced bacterial numbers in peripheral organs by several magnitudes. Acetate treatment improved the sepsis course even when applied several hours after onset of the infection, which recommends GPR43 as a potential target for sepsis therapy. Our study indicates that the severity of sepsis depends on transient neutrophil priming by appropriate blood acetate concentrations. Therapeutic interventions based on GPR43 stimulation could become valuable strategies for reducing sepsis-associated morbidity and mortality.

SUBMITTER: Schlatterer K

PROVIDER: S-EPMC8324776 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Sensing of microbial products by innate immune cells skew their transcriptional program to optimize anti-microbial defences. Chromatin remodeling by histone deacetylases (HDACs) plays a fundamental role in tailoring gene expression. HDAC inhibitors are among the most promising anti-cancer drugs and possess intrinsic anti-inflammatory properties. Yet, the influence of HDAC inhibition on innate immune responses to microbial infection is unknown. Here we show that HDAC inhibitors repress the expression of less than 10% of the genes expressed at baseline in BM-derived macrophages. In sharp contrast, HDAC inhibitors strongly interfere with transcriptome remodeling induced by LPS and Pam3CSK4, affecting the expression of 30-70% of genes modulated by microbial stimuli. Strikingly, HDAC inhibitors target the expression of numerous genes involved in anti-microbial host defences, encoding for microbial sensors, cytokines, chemokines, growth factors and their receptors, adhesion and signaling molecules, and molecules involved in antigen processing and presentation. At the molecular level, HDAC inhibitors do not impair mitogen-activated protein kinase, NF-kB, interferon-related factor signal and STAT1 transduction pathways, but inhibit NF-kB p65 recruitment to the promoter region of HDAC inhibitor-sensitive genes. HDAC inhibitors also inhibit the response of mouse and human DCs, splenocytes and whole blood to a broad range of microbial products and microorganisms. In agreement with these in vitro findings, HDAC inhibitors increase bacterial burden and sensitize mice to sub-lethal infection with Klebsiella pneumoniae and Candida albicans. Conversely, HDAC inhibitors confer protection in models of Pam3CSK4-induced fulminant toxic shock and severe sepsis following cecal ligation and puncture. Overall, these data substantiate the concept of immunomodulation by HDAC inhibitors, and suggest that these drugs could represent efficacious adjunctive therapy of severe sepsis. Mus musculus cells were grown in presence of LPS or LPS + TSA and pam or pam + TSA and hybrydised against a cRNA pool UMRR (from Mus musculus cells).

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Acetate sensing by GPR43 alarms neutrophils and protects from severe sepsis.

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