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Macrophage-Derived Angiopoietin-Like Protein 2 Exacerbates Brain Damage by Accelerating Acute Inflammation after Ischemia-Reperfusion.

ABSTRACT: Ischemic stroke is a leading cause of death and disability worldwide. Several reports suggest that acute inflammation after ischemia-reperfusion exacerbates brain damage; however, molecular mechanisms underlying this effect remain unclear. Here, we report that MAC-3-positive immune cells, including infiltrating bone marrow-derived macrophages and activated microglia, express abundant angiopoietin-like protein (ANGPTL) 2 in ischemic mouse brain in a transient middle cerebral artery occlusion (MCAO) model. Both neurological deficits and infarct volume decreased in transient MCAO model mice established in Angptl2 knockout (KO) relative to wild-type mice. Acute brain inflammation after ischemia-reperfusion, as estimated by expression levels of pro-inflammatory cytokines such as interleukin (IL)-1? and tumor necrosis factor alpha (TNF)-?, was significantly suppressed in Angptl2 KO compared to control mice. Moreover, analysis employing bone marrow chimeric models using Angptl2 KO and wild-type mice revealed that infiltrated bone marrow-derived macrophages secreting ANGPTL2 significantly contribute to acute brain injury seen after ischemia-reperfusion. These studies demonstrate that infiltrating bone marrow-derived macrophages promote inflammation and injury in affected brain areas after ischemia-reperfusion, likely via ANGPTL2 secretion in the acute phase of ischemic stroke.

SUBMITTER: Amadatsu T

PROVIDER: S-EPMC5115716 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Macrophage-Derived Angiopoietin-Like Protein 2 Exacerbates Brain Damage by Accelerating Acute Inflammation after Ischemia-Reperfusion.

Amadatsu Toshihiro T Morinaga Jun J Kawano Takayuki T Terada Kazutoyo K Kadomatsu Tsuyoshi T Miyata Keishi K Endo Motoyoshi M Kasamo Daiki D Kuratsu Jun-Ichi JI Oike Yuichi Y

PloS one 20161118 11

Ischemic stroke is a leading cause of death and disability worldwide. Several reports suggest that acute inflammation after ischemia-reperfusion exacerbates brain damage; however, molecular mechanisms underlying this effect remain unclear. Here, we report that MAC-3-positive immune cells, including infiltrating bone marrow-derived macrophages and activated microglia, express abundant angiopoietin-like protein (ANGPTL) 2 in ischemic mouse brain in a transient middle cerebral artery occlusion (MCA ...[more]

PMID: 27861531

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Project description:BACKGROUND & AIMS:Hepatic ischemia-reperfusion injury (IRI), characterized by exogenous antigen-independent local inflammation and hepatocellular death, represents a risk factor for acute and chronic rejection in liver transplantation. We aimed to investigate the molecular communication involved in the mechanism of liver IRI. METHODS:We analyzed human liver transplants, primary murine macrophage cell cultures and IR-stressed livers in myeloid-specific heme oxygenase-1 (HO-1) gene mutant mice, for anti-inflammatory and cytoprotective functions of macrophage-specific HO-1/SIRT1 (sirtuin 1)/p53 (tumor suppressor protein) signaling. RESULTS:Decreased HO-1 expression in human post-reperfusion liver transplant biopsies correlated with a deterioration in hepatocellular function (serum ALT; p<0.05) and inferior patient survival (p<0.05). In the low HO-1 liver transplant biopsy group, SIRT1/Arf (alternative reading frame)/p53/MDM2 (murine double minute 2) expression levels decreased (p<0.05) while cleaved caspase 3 and frequency of TUNEL+cells simultaneously increased (p<0.05). Immunofluorescence showed macrophages were the principal source of HO-1 in human and mouse IR-stressed livers. In vitro macrophage cultures revealed that HO-1 induction positively regulated SIRT1 signaling, whereas SIRT1-induced Arf inhibited ubiquitinating activity of MDM2 against p53, which in turn attenuated macrophage activation. In a murine model of hepatic warm IRI, myeloid-specific HO-1 deletion lacked SIRT1/p53, exacerbated liver inflammation and IR-hepatocellular death, whereas adjunctive SIRT1 activation restored p53 signaling and rescued livers from IR-damage. CONCLUSION:This bench-to-bedside study identifies a new class of macrophages activated via the HO-1-SIRT1-p53 signaling axis in the mechanism of hepatic sterile inflammation. This mechanism could be a target for novel therapeutic strategies in liver transplant recipients. LAY SUMMARY:Post-transplant low macrophage HO-1 expression in human liver transplants correlates with reduced hepatocellular function and survival. HO-1 regulates macrophage activation via the SIRT1-p53 signaling network and regulates hepatocellular death in liver ischemia-reperfusion injury. Thus targeting this pathway in liver transplant recipients could be of therapeutic benefit.

Dataset Information

Macrophage-Derived Angiopoietin-Like Protein 2 Exacerbates Brain Damage by Accelerating Acute Inflammation after Ischemia-Reperfusion.

Publications

Macrophage-Derived Angiopoietin-Like Protein 2 Exacerbates Brain Damage by Accelerating Acute Inflammation after Ischemia-Reperfusion.

Similar Datasets

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