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Inflammatory macrophage to hepatocyte signals can be prevented by extracellular vesicle reprogramming.

ABSTRACT: Macrophage-derived extracellular vesicles (EVs) play key roles in intercellular communication. Within the liver, they have been linked to several inflammatory diseases including nonalcoholic fatty liver disease (NAFLD). In this study, we found that inflammatory macrophages cause injury to hepatocytes, in part by a cell-cell crosstalk phenomenon involving the secretion of EVs containing pro-inflammatory cargo. Incorporation of these inflammatory signals into EV requires the cleavage of the trafficking adaptor protein RILP, which, as previously shown, results from inflammasome-mediated caspase-1 activation. RILP cleavage can be blocked by overexpressing a dominant negative, non-cleavable form of RILP (ncRILP). EV preparations from ncRILP-expressing cells are, by themselves, sufficient to suppress inflammatory effects in hepatocytes. These results suggest that both direct RILP manipulation and/or supplying ncRILP-modified EVs could be used as a novel therapy for the treatment of inflammatory liver diseases.

SUBMITTER: Ghosh P

PROVIDER: S-EPMC10184766 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature

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Inflammatory macrophage to hepatocyte signals can be prevented by extracellular vesicle reprogramming.

Ghosh Priyanka P Sasaki Kyo K Pulido Ruiz Isabel Aranzazu IA King Kayla E KE Weinman Steven A SA Wozniak Ann L AL

Journal of cell science 20230512 9

Macrophage-derived extracellular vesicles (EVs) play key roles in intercellular communication. Within the liver, they have been linked to several inflammatory diseases including nonalcoholic fatty liver disease (NAFLD). In this study, we found that inflammatory macrophages cause injury to hepatocytes, in part by a cell-cell crosstalk phenomenon involving the secretion of EVs containing pro-inflammatory cargo. Incorporation of these inflammatory signals into EV requires the cleavage of the traffi ...[more]

PMID: 37051862

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Project description:Background: The pathophysiology of non-alcoholic steatohepatitis involves hepatocyte lipotoxicity due to excess saturated free fatty acids and concomitant proinflammatory macrophage effector responses. These include the infiltration of macrophages into hepatic cords in response to incompletely understood stimuli. Stressed hepatocytes release an increased number of extracellular vesicles (EVs), which are known to participate in intercellular signaling and coordination of the behavior of immune cell populations via their cargo. We hypothesized that hepatocyte-derived lipotoxic EVs that are enriched in sphingosine 1-phosphate (S1P) are effectors of macrophage infiltration in the hepatic microenvironment. Methods: Lipotoxic EVs were isolated from palmitate treated immortalized mouse hepatocytes and characterized by nanoparticle tracking analysis. Lipotoxic EV sphingolipids were quantified using tandem mass spectrometry. Wildtype and S1P1 receptor knockout bone marrow-derived macrophages were exposed to lipotoxic EV gradients in a microfluidic gradient generator. Macrophage migration toward EV gradients was captured by time-lapse microscopy and analyzed to determine directional migration. Fluorescence-activated cell sorting along with quantitative PCR and immunohistochemistry were utilized to characterize the cell surface expression of S1P1 receptor on intrahepatic leukocytes and hepatic expression of S1P1 receptor, respectively. Results: Palmitate treatment induced the release of EVs. These EVs were enriched in S1P. Palmitate-induced S1P enriched EVs were chemoattractive to macrophages. EV S1P enrichment depended on the activity of sphingosine kinases 1 and 2, such that, pharmacological inhibition of sphingosine kinases 1 and 2 resulted in a significant reduction in EV S1P cargo without affecting the number of EVs released. When exposed to EVs derived from cells treated with palmitate in the presence of a pharmacologic inhibitor of sphingosine kinases 1 and 2, macrophages displayed diminished chemotactic behavior. To determine receptor-ligand specificity, we tested the migration responses of macrophages genetically deleted in the S1P1 receptor toward lipotoxic EVs. S1P1 receptor knockout macrophages displayed a marked reduction in their chemotactic responses toward lipotoxic palmitate-induced EVs. Conclusions:Palmitate-induced lipotoxic EVs are enriched in S1P through sphingosine kinases 1 and 2. S1P-enriched EVs activate persistent and directional macrophage chemotaxis mediated by the S1P1 receptor, a potential signaling axis for macrophage infiltration during hepatic lipotoxicity, and a potential therapeutic target for non-alcoholic steatohepatitis.

Project description:ObjectivesTo investigate the mechanism of comorbidity between non-alcoholic fatty liver disease (NAFLD) and atherosclerosis (AS) based on metabolomics and network pharmacology.MethodsSix ApoE－/－ mice were fed with a high-fat diet for 16 weeks as a comorbid model of NAFLD and AS (model group). Normal diet was given to 6 wildtype C57BL/6J mice (control group). Serum samples were taken from both groups for a non-targeted metabolomics assay to identify differential metabolites. Network pharmacology was applied to explore the possible mechanistic effects of differential metabolites on AS and NAFLD. An in vitro comorbid cell model was constructed using NCTC1469 cells and RAW264.7 macrophage. Cellular lipid accumulation, cell viability, morphology and function of mitochondria were detected with oil red O staining, CCK-8 assay, transmission electron microscopy and JC-1 staining, respectively.ResultsA total of 85 differential metabolites associated with comorbidity of NAFLD and AS were identified. The top 20 differential metabolites were subjected to network pharmacology analysis, which showed that the core targets of differential metabolites related to AS and NAFLD were STAT3, EGFR, MAPK14, PPARG, NFKB1, PTGS2, ESR1, PPARA, PTPN1 and SCD. The Kyoto Encyclopedia of Genes and Genomes showed the top 10 signaling pathways were PPAR signaling pathway, AGE-RAGE signaling pathway in diabetic complications, alcoholic liver disease, prolactin signaling pathway, insulin resistance, TNF signaling pathway, hepatitis B, the relax in signaling pathway, IL-17 signaling pathway and NAFLD. Experimental validation showed that lipid metabolism-related genes PPARG, PPARA, PTPN1, and SCD were significantly changed in hepatocyte models, and steatotic hepatocytes affected the expression of macrophage inflammation-related genes STAT3, NFKB1 and PTGS2; steatotic hepatocytes promoted the formation of foam cells and exacerbated the accumulation of lipids in foam cells; the disrupted morphology, impaired function, and increased reactive oxygen species production were observed in steatotic hepatocyte mitochondria, while the formation of foam cells aggravated mitochondrial damage.ConclusionsAbnormal lipid metabolism and inflammatory response are distinctive features of comorbid AS and NAFLD. Hepatocyte steatosis causes mitochondrial damage, which leads to mitochondrial dysfunction, increased reactive oxygen species and activation of macrophage inflammatory response, resulting in the acceleration of AS development.

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Inflammatory macrophage to hepatocyte signals can be prevented by extracellular vesicle reprogramming.

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Inflammatory macrophage to hepatocyte signals can be prevented by extracellular vesicle reprogramming.

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