Hui Liang1,2, Nathanael Matei2, Devin W McBride3, Yang Xu2, Zhenhua Zhou2, Jiping Tang2, Benyan Luo4, John H Zhang2. 1. Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. 2. Department of Physiology and Pharmacology and Department of Anesthesiology, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA. 3. The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA. 4. Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. luobenyan@zju.edu.cn.
Abstract
BACKGROUND: Nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) plays an important role in mediating inflammatory responses during ischemic stroke. Bile acid receptor Takeda-G-protein-receptor-5 (TGR5) has been identified as an important component in regulating brain inflammatory responses. In this study, we investigated the mechanism of TGR5 in alleviating neuroinflammation after middle cerebral artery occlusion (MCAO). METHODS: Sprague-Dawley rats were subjected to MCAO and TGR5 agonist INT777 was administered intranasally 1 h after MCAO. Small interfering RNAs (siRNA) targeting TGR5 and Pellino3 were administered through intracerebroventricular injection 48 h before MCAO. Infarct volumes and neurologic scores were evaluated, and ELISA, flow cytometry, immunofluorescence staining, immunoblotting, and co-immunoprecipitation were used for the evaluations. RESULTS: Endogenous TGR5 and Pellino3 levels increased after MCAO. TGR5 activation by INT777 significantly decreased pro-inflammatory cytokine, cleaved caspase-8, and NLRP3 levels, thereby reducing brain infarctions; both short- and long-term neurobehavioral assessments showed improvements. Ischemic damage induced the interaction of TGR5 with Pellino3. Knockdown of either TGR5 or Pellino3 increased the accumulation of cleaved caspase-8 and NLRP3, aggravated cerebral impairments, and abolished the anti-inflammatory effects of INT777 after MCAO. CONCLUSIONS: TGR5 activation attenuated brain injury by inhibiting neuroinflammation after MCAO, which could be mediated by Pellino3 inhibition of caspase-8/NLRP3.
BACKGROUND:Nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) plays an important role in mediating inflammatory responses during ischemic stroke. Bile acid receptor Takeda-G-protein-receptor-5 (TGR5) has been identified as an important component in regulating brain inflammatory responses. In this study, we investigated the mechanism of TGR5 in alleviating neuroinflammation after middle cerebral artery occlusion (MCAO). METHODS:Sprague-Dawley rats were subjected to MCAO and TGR5 agonist INT777 was administered intranasally 1 h after MCAO. Small interfering RNAs (siRNA) targeting TGR5 and Pellino3 were administered through intracerebroventricular injection 48 h before MCAO. Infarct volumes and neurologic scores were evaluated, and ELISA, flow cytometry, immunofluorescence staining, immunoblotting, and co-immunoprecipitation were used for the evaluations. RESULTS: Endogenous TGR5 and Pellino3 levels increased after MCAO. TGR5 activation by INT777 significantly decreased pro-inflammatory cytokine, cleaved caspase-8, and NLRP3 levels, thereby reducing brain infarctions; both short- and long-term neurobehavioral assessments showed improvements. Ischemic damage induced the interaction of TGR5 with Pellino3. Knockdown of either TGR5 or Pellino3 increased the accumulation of cleaved caspase-8 and NLRP3, aggravated cerebral impairments, and abolished the anti-inflammatory effects of INT777 after MCAO. CONCLUSIONS:TGR5 activation attenuated brain injury by inhibiting neuroinflammation after MCAO, which could be mediated by Pellino3 inhibition of caspase-8/NLRP3.
Authors: Juan Carlos Pena-Philippides; Yirong Yang; Olga Bragina; Sean Hagberg; Edwin Nemoto; Tamara Roitbak Journal: Transl Stroke Res Date: 2014-02-20 Impact factor: 6.829
Authors: Nuruddeen D Lewis; Lori A Patnaude; Josephine Pelletier; Donald J Souza; Susan M Lukas; F James King; Jonathan D Hill; Dimitria E Stefanopoulos; Kelli Ryan; Sudha Desai; Donna Skow; Stefan G Kauschke; Andre Broermann; Daniel Kuzmich; Christian Harcken; Eugene R Hickey; Louise K Modis Journal: PLoS One Date: 2014-06-26 Impact factor: 3.240