Apolipoprotein D, a Novel Ligand for CD36, Is Essential for Blood–Brain Barrier Integrity
Abstract
BACKGROUND: The disruption of the blood–brain barrier (BBB) is a central pathogenic event in many central nervous system disorders. However, the mechanisms regulating BBB function remain incompletely understood, and effective treatments are lacking. Brain mural cells differ significantly from their peripheral counterparts, a distinction likely critical for maintaining BBB integrity. METHODS: We combined proteomic profiling of human brain vs peripheral mural cells with multiple ischemic stroke models (global apolipoprotein D [ApoD] knockout, mural cell–specific ApoD knockout, and adeno-associated virus–mediated ApoD overexpression) to evaluate the role of ApoD in BBB integrity. Mechanistic studies (co-immunoprecipitation, binding assays, including surface plasmon resonance, bio-layer interferometry, cross-linking mass spectrometry, and CD36 loss-of-function approaches, both in vitro and in vivo) were performed to determine how ApoD interacts with CD36 and inhibits its signaling. Finally, we assessed the effect of ApoD glycosylation on CD36 binding and tested therapeutic delivery of hypoglycosylated ApoD in stroke. RESULTS: Our study has shown an increased expression of ApoD in mural cells after ischemic stroke. We found that mural cell–derived ApoD functions as an inhibitory ligand of endothelial CD36, suppressing pathological endothelial proliferation, preserving BBB integrity, and promoting neurological recovery. Additionally, overexpression of ApoD in mural cells improved BBB integrity and enhanced functional recovery in ApoD -null mice. Mechanistically, ApoD competes with long-chain fatty acids for CD36 binding and directly attenuates downstream CD36 signaling. Furthermore, we reveal that peripheral hyperglycosylated ApoD (hyperglyco-ApoD) showed minimal effect on BBB integrity maintenance, whereas hypoglycosylation of ApoD enhances its binding affinity to CD36, amplifying its therapeutic efficacy. Exogenous administration of hypoglyco-ApoD via vein injection profoundly inhibited BBB disruption and improved neural function, especially in aging stroke. CONCLUSIONS: Our work identifies a previously unrecognized paracrine mechanism in which mural cell–derived ApoD directly engages endothelial CD36 to restrain pathological endothelial proliferation, thereby preserving BBB integrity and promoting neurological recovery after stroke. These findings further suggest that hypoglycosylated ApoD, with its higher CD36-binding affinity, merits investigation as a potential strategy to enhance BBB repair in central nervous system disorders.
Article Details
Authors (33)
Chang-Xiong Gong
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Pei-Xia Shi
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Yan-Jie Huang
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Yue Dai
Lin-Lin Hu
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Xiao-Feng Cheng
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Shuang Zhang
Meng-ting He
Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, The Key Laboratory of Anti-inflammatory of Immune Medicines, Ministry of Education, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University
Jian-Hua Wang
Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China (M.-T.H., J.-H.W., M.-Q.D.).
Zhao-You Meng
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Yi-Liang Fang
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Bin-Qiao Wang
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Yuan Zhao
Cheng-Kang He
Medical Care Center, Shigatse Branch of Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-K.H.).
Guo-Qiang Yang
Department of Neurology, Huaihai Hospital, Xuzhou medical University, Xuzhou, China (G.-Q.Y.).
Wen-Jie Zi
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Zhong-Ming Qiu
Department of Neurology, the 903rd Hospital of The Chinese People’s Liberation Army. Hangzhou, China (Z.-M.Q.).
Feng-Li Li
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Sen Lin
State Key Laboratory of Chemistry for NBC Hazards Protection, College of Chemistry
Hui Lu
Chen-Hao Zhao
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Chi Zhang
Zhen-Yu Liu
Department of Urology, General Hospital of central Theater Command of Chinese People’s Liberation Army, Wuhan, Hubei, China (Z.-Y.L.).
Meng-Qiu Dong
Qin Ouyang
College of Pharmacy, Third Military Medical University, Shapingba, Chongqing 400038, China
Hong-Ting Zheng
Department of Endocrinology, Xinqiao Hospital, the Army Medical University, Chongqing, China (H.-T.Z.).
Jian-Qin Niu
Department of Histology and Embryology, the Army Medical University, Chongqing, China (J.-Q.N., F.M.).
Feng Mei
Bao-Liang Sun
Department of Neurology, the Second Affiliated Hospital, Key Laboratory of Cerebral Microcirculation in Universities of Shandong, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, Shandong, China (B.-L.S.).
Jin Zhou
Department of Oncology Sichuan Cancer Hospital Chengdu China
Qi Xie
Fang-Fei Li
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).
Qing-Wu Yang
Department of Neurology, Xinqiao Hospital, the Army Medical University, Chongqing, China (C.-X.G., P.-X.S., Y.-J.H., L.-L.H., X.-F.C., S.Z., M.-T.H., Z.-Y.M., Y.-L.F., B.-Q.W., Y.Z., W.-J.Z., F.-L.L., S.L., H.L., C.-H.Z., Q.X., F.-F.L., Q.-W.Y.).