Browsing by Author "Zhang, John H."
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Item Inhibition of PAR-2 attenuates neuroinflammation and improves short-term neurocognitive functions via ERK1/2 signaling following asphyxia-induced cardiac arrest in rats(Lippincott Williams & Wilkins, 2020-01-14) Ocak, Umut; Huang, Lei; Zuo, Gang; Yan, Jun; Hu, Xin; Song, Zhijun; Zhang, John H.; Ocak, Pınar Eser; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Nöroşirürji Anabilim Dalı.; 0000-0003-0132-9927; 57200969645Objective: Global cerebral ischemia-induced neuroinflammation causes neurofunctional impairment following cardiac arrest. Previous studies have demonstrated that the activation of protease-activated receptor-2 (PAR-2) contributes to neuroinflammation. In the present study, we aimed to determine the potential treatment effect of PAR-2 inhibition against neuroinflammation in the setting of asphyxial CA(ACA) in rats. Methods: A total of 116 adult, male Sprague-Dawley rats were randomly divided into Sham (n = 18) and ACA (n = 98) groups. Time course, short-term outcome, and mechanism studies were conducted. All drugs were delivered intranasally. The effect of PAR-2 inhibitor FSLLRY-NH2 on neurocognitive functions was assessed by neurologic deficit score, number of seizures, and T-maze test, while hippocampal neuronal degeneration was evaluated by Fluoro-Jade C staining after ACA. Western blotting was performed for the mechanism study at 24 h following ACA. Selective PAR-2 agonist (AC55541) and ERK1/2 inhibitor (PD98059) were used for intervention. Results: Inhibition of PAR-2 decreased neuroinflammation, reduced the number of degenerating hippocampal neurons and improved neurocognitive functions following ACA. PAR-2 activator alone exerted opposite effects to PAR-2 inhibitor. PAR-2mediated the augmented brain levels of proinflammatory cytokines by promoting the phosphorylation of ERK1/2. Conclusions: PAR-2 inhibition diminished neuroinflammation and thereby reduced hippocampal neuronal degeneration and neurocognitive impairment following ACA. This effect was at least partly mediated via the PAR-2/ERK1/2 signaling.Item Overexpression of Mfsd2a attenuates blood brain barrier dysfunction via Cav-1/Keap-1/Nrf-2/HO-1 pathway in a rat model of surgical brain injury(Academic Press Inc Elsevier Science, 2020-01-16) Ocak, Umut; Sherchan, Prativa; Gamdzyk, Marcin; Tang, Jiping; Zhang, John H.; Ocak, Pınar Eser; Bursa Uludağ Üniversitesi/Tıp Fakültesi.; 0000-0003-0132-9927; AAI-2073-2021; 57200969645Introduction: Disruption of the blood brain barrier (BBB) and subsequent cerebral edema formation is one of the major adverse effects of brain surgery, leading to postoperative neurological dysfunction. Recently, Mfsd2a has been shown to have a crucial role for the maintenance of BBB functions. In this study, we aimed to evaluate the role of Mfsd2a on BBB disruption following surgical brain injury (SBI) in rats. Materials and methods: Rats were subjected to SBI by partial resection of the right frontal lobe. To evaluate the effect of Mfsd2a on BBB permeability and neurobehavior outcome following SBI, Mfsd2a was either over-expressed or downregulated in the brain by administering Mfsd2a CRISPR activation or knockout plasmids, respectively. The potential mechanism of Mfsd2a-mediated BBB protection through the cav-1/Nrf-2/HO-1 signaling pathway was evaluated. Results: Mfsd2a levels were significantly decreased while cav-1, Nrf-2 and HO-1 levels were increased in the right frontal perisurgical area following SBI. When overexpressed, Mfsd2a attenuated brain edema and abolished neurologic impairment caused by SBI while downregulation of Mfsd2a expression further deteriorated BBB functions and worsened neurologic performance following SBI. The beneficial effect of Mfsd2a overexpression on BBB functions was associated with diminished expression of cav-1, increased Keap-1/Nrf-2 dissociation and further augmented levels of Nrf-2 and HO-1 in the right frontal perisurgical area, leading to enhanced levels of tight junction proteins following SBI. The BBB protective effect of Mfsd2a was blocked by selective inhibitors of Nrf-2 and HO-1. Conclusions: Mfsd2a attenuates BBB disruption through cav-1/Nrf-2/HO-1 signaling pathway in rats subjected to experimental SBI.Publication Targeting oxidative stress and inflammatory response for blood-brain barrier protection in intracerebral hemorrhage(Mary Ann Liebert, Inc, 2022-06-08) Chen, Shengpan; Li, Lingzhi; Peng, Chao; Bian, Chunjing; Zhang, John H.; Yang, Yong; Zhou, Dong; Chen, Guangzhong; Luo, Yumin; Ocak, Pınar Eser; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Nöroşurji Anabilim Dalı.; AAI-2073-2021Significance: Blood-brain barrier (BBB) disruption is a major pathological change after intracerebral hemorrhage (ICH) and is both the cause and result of oxidative stress and of the immune response post-ICH. These processes contribute to ICH-induced brain injury.Recent Advances: After the breakdown of cerebral vessels, blood components, including erythrocytes and their metabolites, thrombin, and fibrinogen, can access the cerebral parenchyma through the compromised BBB, triggering oxidative stress and inflammatory cascades. These aggravate BBB disruption and contribute to further infiltration of blood components, resulting in a vicious cycle that exacerbates brain edema and neurological injury after ICH. Experimental and clinical studies have highlighted the role of BBB disruption in ICH-induced brain injury.Critical Issues: In this review, we focus on the strategies to protect the BBB in ICH. Specifically, we summarize the evidence and the underlying mechanisms, including the ICH-induced process of oxidative stress and inflammatory response, and we highlight the potential therapeutic targets to protect BBB integrity after ICH.Future Directions: Future studies should probe the mechanism of ferroptosis as well as oxidative stress-inflammation coupling in BBB disruption after ICH and investigate the effects of antioxidants and immunomodulatory agents in more ICH clinical trials.