engleski

Immunotherapeutic potential of peptidoglycan-monomer linked with zinc in old mice

Although different theories try to explain the aging process, it is generally accepted that there is a correlation between the aging and the accumulation of oxidatively damaged proteins, lipids and nucleic acids, as well as reactive nitrogen species (RNS), which are widely implicated in the inflammatory process and responsible for a variety of age-related dysfunction. The elimination of deleterious effects of ROS/RNS are dependent on their concentration and the microenvironment in which ROS/RNS are released, while in the processes of the recognition and elimination of potentially harmful altered macromolecules, and general coping with stress are involved the cells of innate and adaptive immune system. Owing to the presence of immunosenescence in elderly and our previous findings that peptidoglycan monomer (PGM), originally prepared by biosynthesis from culture fluids of Gram (+) Brevibacterium divaricatum and its new analog PGM-Zn have marked immunocorrective and hepatoprotective properties in experimental models of immunodeficiency (halothane anesthesia and obstructive jaundice) in this study we attempted to investigate the effects of in vivo application of PGM-Zn in very old mice (aged 2 years) estimating the phenotypic and functional characteristic of intrahepatic and splenic mononuclear lymphatic cells (MNLC), and comparing the data with similarly treated young (2 month old) C57BL6 mice. For this purpose both age groups of mice were treated during the 6 days (every second day) with 3 injections of PGM-Zn (10 mg/kg i.p.) or with the same amount of the solvent. Two days after the last injection, the phenotype of lymphatic cells was determined by FACS staining, and the spontaneous cytotoxic activity of freshly isolated intrahepatic and splenic MNLC was measured against NK-sensitive (YAC-1) and against NKT-sensitive targets (syngeneic thymocytes). The results have shown that in the control-old mice very significant changes occur particularly in the liver. Thus, the proportion of intrahepatic CD3+, CD8+, CD122+ (IL-2Rb+) and CD3+/CD122+ cells was found to be significantly greater, and the proportion of NK1.1+ cells lower than in the control-young mice. Treatment with PGM-Zn in both age groups significantly increased the proportion of NK1.1+, CD69+ and CD3+/NK1.1+ cells, but this increase was less expressed in very old mice. On the contrary, PGM-Zn in old mice markedly decreased the percentage of hepatic CD8+ T cells, and CD122+ NKT cells. Similar changes were not found in the spleen, where, in the control-old group was found a significantly less proportion of CD8+ cells and a greater inhibitory effects of PGM-Zn on CD19+ cells. Simultaneously, we noticed that hepatic MNLCs obtained from control-very old mice were markedly less cytotoxic against YAC-1 than those obtained from young mice (p<0.0001). Splenic MNLC obtained from very old mice in comparison to “ young” cells were, however, significantly more cytotoxic against the syngeneic thymocytes (p<0.0001), suggesting the effects of auto reactive clones of cells. Furthermore, in very old mice this type of cytotoxicity might be additionally stimulated by in vivo application of PGM-Zn. On the contrary, in young mice PGM-Zn more stimulated the NK-dependent cytotoxicity against YAC-1 target. The data emphasize the role of the liver in immunosenescence and TLR-mediated control of cell-mediated cytotoxicities, orchestrated by dendritic cells and distinct types of NKT cells.

peptidoglycan-monomer with Zn ; very old mice ; liver ; spleen ; YAC-1 ; syngeneic thymocytes

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