Kyeong-A Kim1, Donghyun Kim1, Jeong-Hyeon Kim1, Young-Jun Shin1, Eun-Sun Kim1, Muhammad Akram1,2, Eun-Hye Kim1, Arshad Majid3, Seung-Hoon Baek4, Ok-Nam Bae5. 1. College of Pharmacy Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Republic of Korea. 2. Faculty of Pharmacy, University of Sindh, Jamshoro, Pakistan. 3. Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, England, UK. 4. College of Pharmacy and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon, Republic of Korea. 5. College of Pharmacy Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Republic of Korea. onbae@hanyang.ac.kr.
Abstract
BACKGROUND: The blood-brain barrier (BBB) maintains homeostasis of the brain environment by tightly regulating the entry of substances from systemic circulation. A breach in the BBB results in increased permeability to potentially toxic substances and is an important contributor to amplification of ischemic brain damage. The precise molecular pathways that result in impairment of BBB integrity remain to be elucidated. Autophagy is a degradation pathway that clears damaged or unnecessary proteins from cells. However, excessive autophagy can lead to cellular dysfunction and death under pathological conditions. METHODS: In this study, we investigated whether autophagy is involved in BBB disruption in ischemia, using in vitro cells and in vivo rat models. We used brain endothelial bEnd.3 cells and oxygen glucose deprivation (OGD) to simulate ischemia in culture, along with a rat ischemic stroke model to evaluate the role of autophagy in BBB disruption during cerebral ischemia. RESULTS: OGD 18 h induced cellular dysfunction, and increased permeability with degradation of occludin and activation of autophagy pathways in brain endothelial cells. Immunostaining revealed that occludin degradation is co-localized with ischemic autophagosomes. OGD-induced occludin degradation and permeability changes were significantly decreased by inhibition of autophagy using 3-methyladenine (3-MA). Enhanced autophagic activity and loss of occludin were also observed in brain capillaries isolated from rats with middle cerebral artery occlusion (MCAO). Intravenous administration of 3-MA inhibited these molecular changes in brain capillaries, and recovered the increased permeability as determined using Evans blue. CONCLUSIONS: Our findings provide evidence that autophagy plays an important role in ischemia-induced occludin degradation and loss of BBB integrity.
BACKGROUND: The blood-brain barrier (BBB) maintains homeostasis of the brain environment by tightly regulating the entry of substances from systemic circulation. A breach in the BBB results in increased permeability to potentially toxic substances and is an important contributor to amplification of ischemic brain damage. The precise molecular pathways that result in impairment of BBB integrity remain to be elucidated. Autophagy is a degradation pathway that clears damaged or unnecessary proteins from cells. However, excessive autophagy can lead to cellular dysfunction and death under pathological conditions. METHODS: In this study, we investigated whether autophagy is involved in BBB disruption in ischemia, using in vitro cells and in vivo rat models. We used brain endothelial bEnd.3 cells and oxygenglucose deprivation (OGD) to simulate ischemia in culture, along with a ratischemic stroke model to evaluate the role of autophagy in BBB disruption during cerebral ischemia. RESULTS: OGD 18 h induced cellular dysfunction, and increased permeability with degradation of occludin and activation of autophagy pathways in brain endothelial cells. Immunostaining revealed that occludin degradation is co-localized with ischemic autophagosomes. OGD-induced occludin degradation and permeability changes were significantly decreased by inhibition of autophagy using 3-methyladenine (3-MA). Enhanced autophagic activity and loss of occludin were also observed in brain capillaries isolated from rats with middle cerebral artery occlusion (MCAO). Intravenous administration of 3-MA inhibited these molecular changes in brain capillaries, and recovered the increased permeability as determined using Evans blue. CONCLUSIONS: Our findings provide evidence that autophagy plays an important role in ischemia-induced occludin degradation and loss of BBB integrity.
Authors: Martin A Schick; Malgorzata Burek; Carola Y Förster; Michiaki Nagai; Christian Wunder; Winfried Neuhaus Journal: Neural Regen Res Date: 2021-07 Impact factor: 5.135
Authors: Amir Ajoolabady; Shuyi Wang; Guido Kroemer; Josef M Penninger; Vladimir N Uversky; Domenico Pratico; Nils Henninger; Russel J Reiter; Askiel Bruno; Kaumudi Joshipura; Hamid Aslkhodapasandhokmabad; Daniel J Klionsky; Jun Ren Journal: Pharmacol Ther Date: 2021-04-03 Impact factor: 13.400