Manganese-Based Nanoparticle Vaccine for Combating Fatal Bacterial Pneumonia.

Bacterial pneumonia is the leading cause of death worldwide among all infectious diseases. However, currently available vaccines against fatal bacterial lung infections, e.g., pneumonic plague, are accompanied by limitations, including insufficient antigen-adjuvant co-delivery and inadequate immune stimulation. Therefore, there is an urgent requirement to develop next-generation vaccines to improve the interaction between antigen and adjuvant, as well as enhance the effects of immune stimulation. This study develops a novel amino-decorated mesoporous manganese silicate nanoparticle (AMMSN) loaded with rF1-V10 (rF1-V10@AMMSN) to prevent pneumonic plague. These results suggest that subcutaneous immunization with rF1-V10@AMMSN in a prime-boost strategy induces robust production of rF1-V10-specific IgG antibodies with a geometric mean titer of 315,844 at day 42 post-primary immunization, which confers complete protection to mice against 50 × LD50 of Yersinia pestis (Y. pestis) challenge via the aerosolized intratracheal route. Mechanistically, rF1-V10@AMMSN can be taken up by dendritic cells (DCs) and promote DCs maturation through activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway and production of type I interferon. This process results in enhanced antigen presentation and promotes rF1-V10-mediated protection against Y. pestis infection. This manganese-based nanoparticle vaccine represents a valuable strategy for combating fatal bacterial pneumonia.

A characterized saponin extract of Panax japonicus suppresses hepatocyte EMT and HSC activation in vitro and CCl4-provoked liver fibrosis in mice: Roles of its modulatory effects on the Akt/GSK3ß/Nrf2 cascade.

BACKGROUND AND PURPOSE: Liver fibrosis constitutes a pathologic condition resulting in a series of advanced liver diseases. Oleanane-type saponins are distinctive active constituents in the medicinal plant Panax japonicus C. A. Mey (P. japonicus). Herein, we assessed protective effects of a characterized saponin extract of rhizomes of P. japonicus (SEPJ) on hepatocyte EMT and HSC activation in vitro and liver fibrosis in mice. We also investigated molecular mechanisms underlying the hepatoprotective activity of SEPJ. METHODS: EMT of AML-12 hepatocytes was evaluated by observing morphology of cells and quantifying EMT marker proteins. Activation of LX-2 HSCs was assessed via scratch assay, transwell assay, and EdU-incorporation assay, and by quantifying activation marker proteins. Liver fibrosis in mice was evaluated by HE, SR, and Masson staining, and by measuring related serum indicators. Immunoblotting and RT-PCR were performed to study mechanisms underlying the action of SEPJ. RESULTS: SEPJ inhibited TGF-ß-induced EMT in AML-12 hepatocytes and activation of LX-2 HSCs. SEPJ elevated Akt phosphorylation at Ser473 and GSK3ß phosphorylation at Ser9 in these cells, giving rise to a descent of the catalytic activity of GSK3ß. These events increased levels of both total and nuclear Nrf2 protein and upregulated expressions of Nrf2-responsive antioxidative genes. In addition, enhanced phosphorylation of Akt and GSK3ß acted upstream of SEPJ-mediated activation of Nrf2. Knockdown of Nrf2 or inhibition of Akt diminished the protective activity of SEPJ against TGF-ß in both AML-12 and LX-2 cells. Our further in vivo experiments revealed that SEPJ imposed a considerable alleviation on CCl4-provoked mouse liver fibrosis. Moreover, hepatic Akt/GSK3ß/Nrf2 cascade were potentiated by SEPJ. Taken together, our results unveiled that SEPJ exerted protective effects against fibrogenic cytokine TGF-ß in vitro and ameliorated liver fibrosis in mice. Mechanistically, SEPJ regulated the Akt/GSK3ß/Nrf2 signaling which subsequently enhanced intracellular antioxidative capacity. CONCLUSIONS: SEPJ inhibits hepatocyte EMT and HSC activation in vitro and alleviates liver fibrosis in mice. Modulation of the Akt/GSK3ß/Nrf2 cascade attributes to its hepatoprotective effects. Our findings support a possible application of SEPJ in the control of liver fibrosis.