Enhanced autophagy and phagocytosis of apoptotic lymphocytes in splenic macrophages of acute ethanol-treated rats: Light and electron microscopic studies
Tsubasa Betsuyaku1, Yuko Ito2, Nicholas Peake3, Abdul Alim Al-Bari4, Gehan El-Akabawy5,6,7 and Nabil Eid8
1Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto, 2Department of General and Gastroenterological Surgery, Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan, 3Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom, 4Department of Pharmacy, Faculty of Science, University of Rajshahi, Rajshahi, Bangladesh, 5Department of Basic Medical Sciences, College of Medicine, 6Centre of Medical and Bio-allied Health Sciences Research, Ajman University, Ajman, United Arab Emirates, 7Department of Anatomy and Embryology, Faculty of Medicine, Menoufia University, Menoufia, Egypt and 8Department of Anatomy, Division of Human Biology, School of Medicine, International Medical University, Kula Lumpur, Malaysia
Corresponding Author: Nabil Eid, Anatomy Department, Division of Human Biology, School of Medicine, International Medical University, 57000 Kula Lumpur, Malaysia. e-mail: nabilsaleheid@imu.edu.my or nabileidm2@gmail.com
Summary. Autophagy is a prosurvival mechanism for the clearance of damaged cellular components, specifically upon exposure to various stressors. In lymphoid organs, excessive ethanol consumption increases lymphocyte apoptosis, resulting in immunosuppression. However, ethanol-induced autophagy and related phagocytosis of apoptotic lymphocytes in the spleen have not been studied yet. Adult male Wistar rats were injected intraperitoneally either with 5 g/kg ethanol or phosphate-buffered saline (as a control group) and then sacrificed 0, 3, 6, and 24 hours after injection. Light and transmission electron microscopy (TEM) findings indicated enhanced T cell apoptosis in the white pulps of ethanol-treated rats (ETRs) compared with the control group, which peaked at 6h and was associated with the accumulation of tingible body macrophages (TBMs). These macrophages exhibited an upregulated autophagic response, as evidenced by enhanced LC3-II (a specific marker of autophagosomes) expression, which peaked at 24h. In addition, double labeling immunofluorescence of LC3-II with lysosomal markers revealed the enhanced formation of autolysosomes in TBMs of ETRs, which was associated with suppression of p62 immunostaining, indicating the enhanced autophagic flux. Interestingly, this elevated autophagic response in ETR TBMs was accompanied by evidence of LC3-associated phagocytosis (LAP) of apoptotic splenocytes. This is based on TUNEL/LC3-II double labeling and TEM observations of phagosomes containing apoptotic bodies, enclosed within phagosomal membranes adjacent to the autophagic vacuoles. It can be concluded that enhanced prosurvival autophagy in splenic TBMs of ETRs and clearing of apoptotic lymphocytes via LAP may contribute to preventing secondary necrosis and autoimmune diseases. Histol Histopathol 39, 853-866 (2024)
Key words: Autophagy, Apoptosis, Ethanol, LAP, Spleen, TBMs, T cells
DOI: 10.14670/HH-18-729
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The Author(s) 2024. Open Access. This article is licensed under a Creative Commons CC-BY International License. |
