Yohimbine-related Alkaloids from Tabernaemontana corymbosa

Five new yohimbine-type indole alkaloids were isolated from the leaves of Tabernaemontana corymbosa. Their structures were determined on the basis of the NMR and Circular Dichroism (CD) spectroscopy

Delayed Cytosolic Exposure of Japanese Encephalitis Virus Double-Stranded RNA Impedes Interferon Activation and Enhances Viral Dissemination in Porcine Cells▿†

Interferon is a principal component of the host antiviral defense system. In this study, abortive focus formation by Japanese encephalitis virus (JEV) in primate cells was accompanied by early interferon induction, while productive focus formation in porcine cells was associated with a late interferon response. Neutralization antibodies against interferon relieved the restricted infection in primate cells, and increasingly larger foci were generated as treatment with exogenous interferon was delayed, thereby establishing a solid correlation between interferon response and viral dissemination. However, delayed interferon induction in JEV-infected porcine cells occurred in the absence of active inhibition by the virus. We further demonstrated that JEV mediates interferon activation through double-stranded RNA and cytosolic pattern recognition receptors. Immunofluorescence and subcellular fractionation studies revealed that double-stranded RNA is concealed in intracellular membranes at an early phase of infection but eventually appears in the cytosol at later periods, which could then allow detection by cytosolic pattern recognition receptors. Interestingly, cytosolic exposure of double-stranded RNA was delayed in porcine cells compared to primate cells, independent of total double-stranded RNA levels and in correlation with the timing of the interferon response. Furthermore, when double-stranded RNA was artificially introduced into the cytosol of porcine cells, more rapid and robust interferon activation was triggered than in viral infection. Thus, cytosolic exposure of JEV double-stranded RNA is imperative for interferon induction, but in cell lines (e.g., porcine cells) with delayed emergence of cytosolic double-stranded RNA, the interferon response is late and viral dissemination is consequently enhanced

Immunobiotic Lactobacillus jensenii Elicits Anti-Inflammatory Activity in Porcine Intestinal Epithelial Cells by Modulating Negative Regulators of the Toll-Like Receptor Signaling Pathway

The effect of Lactobacillus jensenii TL2937 on the inflammatory immune response triggered by enterotoxigenic Escherichia coli (ETEC) and lipopolysaccharide (LPS) in a porcine intestinal epitheliocyte cell line (PIE cells) was evaluated. Challenges with ETEC or LPS elicited Toll-like receptor 4 (TLR4)-mediated inflammatory responses in cultured PIE cells, indicating that our cell line may be useful for studying inflammation in the guts of weaning piglets. In addition, we demonstrated that L. jensenii TL2937 attenuated the expression of proinflammatory cytokines and chemokines caused by ETEC or LPS challenge by downregulating TLR4-dependent nuclear factorκB (NF-κB) and mitogen-activated protein kinase (MAPK) activation. Furthermore, we demonstrated that L. jensenii TL2937 stimulation of PIE cells upregulated three negative regulators of TLRs: A20, Bcl-3, and MKP-1, deepening the understanding of an immunobiotic mechanism of action. L. jensenii TL2937-mediated induction of negative regulators of TLRs would have a substantial physiological impact on homeostasis in PIE cells, because excessive TLR inflammatory signaling would be downregulated. These results indicated that PIE cells can be used to study the mechanisms involved in the protective activity of immunobiotics against intestinal inflammatory damage and may provide useful information for the development of new immunologically functional feeds that help to prevent inflammatory intestinal disorders, including weaning-associated intestinal inflammation