Photobiomodulation Therapy Inhibit the Activation and Secretory of Astrocytes by Altering Macrophage Polarization
Spinal cord injury (SCI) stimulates reactive astrogliosis and the infiltration of macrophages, which interact with each other at the injured area. We previously found Photobiomodulation (PBM) significantly decreases the number of M1 macrophages at the injured area of SCI. But the exact nature of the astrocyte response following PBM and relationship with the macrophage have not been explored in detail. In this study, a BALB/c mice model with standardized bilateral spinal cord compression and a macrophage-astrocyte co-culture model were applied to study effects of PBM on astrocytes. Results showed that PBM inhibit the expression of the astrocyte markers glial fibrillary acidic protein (GFAP) and the secretion of chondroitin sulfate proteoglycans (CSPG) in the para-epicenter area, decrease the number of M1 macrophage in vivo. The in vitro experiments indicated M1 macrophages promote the cell viability of astrocytes and the expression of CSPG. However, PBM significantly inhibited the expression of GFAP, decreased activation of astrocyte, and downregulated the expression of CSPG by regulating M1 macrophages. These results demonstrate that PBM may regulate the interaction between macrophages and astrocytes after spinal cord injury, which inhibited the formation of glial scar.
KeywordsSpinal cord injury Photobiomodulation Astrocyte Macrophage Chondroitin sulfate proteoglycans
ZW and XYH designed and supervised experiments; JKS, JWZ, KL,TD, XYH and ZW wrote the manuscript and analyzed the data; JKS, JWZ, KL, QZ, ZWL and LQ developed the PBM-Macrophage irradiation model and performed the molecular biology experiment; JKS, JWZ, KL, QZ, JWS, JXZ performed the immunofluorescence staining.
This study was funded by Grants from the National Natural Science Foundation of China (Grant Nos. 81572151, 81070996, 81101352) and Science and Technology Department of Shaanxi Province (Grant Nos. 2016SF-143, 2017SF-021).
Compliance with Ethical Standards
Conflict of interest
Jiakai Sun, Jiawei Zhang, Kun Li, Qiao Zheng, Jiwei Song, Zhuowen Liang, Tan Ding, Lin Qiao, Jianxin Zhang, Xueyu Hu, Zhe Wang declare that they have no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
All animal care and experimental programs were conducted according to standard All applicable international and national ethical guidelines (National Institutes of Health Guide to the use of Laboratory Animals) and approved by the Animal Care and Use Committee of the Fourth Military Medical University. All efforts were made to minimize the number of mice used and their suffering.
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