Browsing by Subject "TBMs"

Now showing 1 - 2 of 2
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    Enhanced autophagy and phagocytosis of apoptotic lymphocytes in splenic macrophages of acute ethanol-treated rats: Light and electron microscopic studies
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2024) Betsuyaku, Tsubasa; Ito, Yuko; Peake, Nicholas; Al Bari, Abdul Alim; El Akabawy, Gehan; Eid, Nabil
    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.
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    Ethanol enhances thymocyte apoptosis and autophagy in macrophages of rat thymi
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2017) Betsuyaku, Tsubasa; Eid, Nabil; Ito, Yuko; Tanaka, Yoshihisa; Otsuki, Yoshinori; Kondo, Yoichi
    Tingible body macrophages (TBMs) play essential roles in the phagocytosis of apoptotic lymphocytes, specifically under exposure to various stressors. Although excessive ethanol consumption may enhance thymocyte apoptosis, reports investigating the autophagic response of the thymus to ethanol toxicity are still lacking. We investigated apoptosis and autophagy in thymi of an animal model of binge ethanol exposure. Adult male Wistar rats were injected intraperitoneally either with 5 g/kg ethanol or phosphate buffer saline (for the control group) and sacrificed 0, 3, 6 and 24 hours after injection. Light and transmission electron microscopy (TEM) studies revealed enhanced formation of TBMs phagocytosing many apoptotic thymocytes in the thymic cortex of the ethanol-treated rats (ETRs), and this formation was particularly marked at 24 h. The macrophages showed signs of activation under TEM and immunofluorescence double labeling with RM4 (a macrophage marker) and iNOS. Additionally, in comparison to the control group, autophagy was enhanced in ETR thymic TBMs as evidenced ultrastructurally by accumulation of autophagic vacuoles, immunohistochemical increases in LC3 puncta, Western blot analysis of the latter protein, and colocalization of LC3 and RM4 in immunofluorescence double labeling. Immunoelectron microscopy also revealed LC3-labeled autophagic vacuoles and apoptotic cell phagosomes in ETR TBMs, suggesting the possibility of LC3-related phagocytosis. This was confirmed by enhanced colocalization of LC3 with lysosomal cathepsins in double labeling. These results indicate that enhanced autophagy in ETR thymic TBMs is not only a cytoprotective mechanism but could also be involved in the clearance of apoptotic thymocytes, thus preventing autoimmune reactions and suppressing inflammatory response.