Modulation Effects of Toxoplasma gondii Histone H2A1 on Murine Macrophages and Encapsulation with Polymer as a Vaccine Candidate.

Toxoplasma gondii (T. gondii) is the most common zoonotic protozoa and has infected about one-third of the population worldwide. Recombinant epitopes encapsulated in nanospheres have advantages over traditional T. gondii vaccines. For an efficient delivery system, poly (DL-lactide-co-glycolide) (PLGA) and chitosan are the most frequently used biodegradable polymeric nanospheres with strong safety profiles. In the present study, we first expressed and purified histone H2A1 of T. gondii using the prokaryotic expression system. The effects of recombinant TgH2A1 on the functions of murine macrophages were then studied. Purified recombinant TgH2A1 was then encapsulated in nanospheres with PLGA and chitosan. After subcutaneous vaccination in mice, the immune response was evaluated by double antibody sandwich ELISA kits. The results from this study showed that PLGA and chitosan loaded with rTgH2A1 could trigger a stronger Th1 oriented immune response and prolong the survival time of mice effectively. In conclusion, PLGA and chitosan nanospheres loaded with histone H2A1 are an effective method for the development of vaccines against T. gondii. Further studies should focus on evaluating the regulatory mechanism of TgH2A1, vaccine potency, and cellular response in chronic T. gondii infections.

An In vivo Immunohistochemical Study on MacroH2A.1 in Lung and Lymph-Node Tissues Exposed to an Asbestiform Fiber.

AIMS: The aim of this study was to investigate MacroH2A.1 immunoexpression in tissues of sheep exposed to FE. BACKGROUND: The correlation between asbestiform fibers, lung cancer, pleural mesothelioma, and other lung diseases is already well established as the pathophisiological pathophysiological respiratory mechanisms involved by inhalation of Fluoro-edenite (FE). The latter is represented by cell proliferation and inducing the release of growth factors, cytokines, and reactive oxygen and nitrite species, with DNA damage that causes chronic inflammation and carcinogenesis. MacroH2A.1, and histone variant, seems to play a role in sensing the metabolic state of the cell and linking it with chromatin. Physiologically, MacroH2A.1 is expressed at low levels in stem cells and it became upregulated during differentiation, preventing reprogramming of induced pluripotent stem cells and after nuclear transfer. In particular, MacroH2A.1 has been shown to explicate a potent antitumor mechanism in vivo as it results upregulated in senescent cells determining a permanent growth-arrest. OBJECTIVE: Evaluate the possible role of the histone variant in the organism in response to deep insight understanding the mechanisms of toxicity and the cellular response to FE. METHODS: Lung and lymph nodes of exposed sheep were selected. Samples were processed for histological and immunihistochemical immunohistochemical evaluations. Densitometric, morphometric, and statistical analysis analyses were conducted. RESULTS: Tissue sections of FE exposed sheep demonstrated overexpression of MacroH2A.1 vs unexposed samples. The data suggest an involvement of these this molecule in the cellular response triggered by FE directed exposure. CONCLUSION: In this contest, MacroH2A.1 overexpression supports its function as an epigenetic stabilizer that helps to establish and maintain differentiated states.

Expression of histone variant, H2A.1 is associated with the undifferentiated state of hepatocyte.

Recent studies suggest the incorporation of histone variants into the chromatin regulate cellular proliferation, differentiation, and de-differentiation. We have earlier reported the increase of H2A.1 variant during sequential de-differentiation of hepatocyte to hepato-cellular carcinoma. Here, we decipher the alterations in expression of H2A.1 and H2A.2 variants during rat liver embryogenesis and regeneration. The expression of H2A.1 and H2A.2, at protein and mRNA level, does not alter in normal cellular proliferation associated with regeneration of liver post PH. In contrast, gradual decrease of H2A.1 with increase of H2A.2 is observed during differentiation of embryonic to adult liver. Furthermore, the accumulation of H2A.1 is higher in embryonic stem cells compared to normal adult liver. Collectively, these data support a strong correlation of H2A.1 expression with undifferentiated cells and overall epigenetic reprogramming in dedifferentiation and maturation of undifferentiated cells, rather than with normal cellular proliferation.