Isoprinosine as a foot-and-mouth disease vaccine adjuvant elicits robust host defense against viral infection through immunomodulation.

Background: Commercial foot-and-mouth disease (FMD) vaccines have limitations, such as local side effects, periodic vaccinations, and weak host defenses. To overcome these limitations, we developed a novel FMD vaccine by combining an inactivated FMD viral antigen with the small molecule isoprinosine, which served as an adjuvant (immunomodulator). Method: We evaluated the innate and adaptive immune responses elicited by the novel FMD vaccine involved both in vitro and in vivo using mice and pigs. Results: We demonstrated isoprinosine-mediated early, mid-term, and long-term immunity through in vitro and in vivo studies and complete host defense against FMD virus (FMDV) infection through challenge experiments in mice and pigs. We also elucidated that isoprinosine induces innate and adaptive (cellular and humoral) immunity via promoting the expression of immunoregulatory gene such as pattern recognition receptors [PRRs; retinoic acid-inducible gene (RIG)-I and toll like receptor (TLR)9], transcription factors [T-box transcription factor (TBX)21, eomesodermin (EOMES), and nuclear factor kappa B (NF-kB)], cytokines [interleukin (IL)-12p40, IL-23p19, IL-23R, and IL-17A)], and immune cell core receptors [cluster of differentiation (CD)80, CD86, CD28, CD19, CD21, and CD81] in pigs. Conclusion: These findings present an attractive strategy for constructing novel FMD vaccines and other difficult-to-control livestock virus vaccine formulations based on isoprinosine induced immunomodulatory functions.

Bestatin, A Pluripotent Immunomodulatory Small Molecule, Drives Robust and Long-Lasting Immune Responses as an Adjuvant in Viral Vaccines.

An inactivated whole-virus vaccine is currently used to prevent foot-and-mouth disease (FMD). Although this vaccine is effective, it offers short-term immunity that requires regular booster immunizations and has several side effects, including local reactions at the vaccination site. To address these limitations, herein, we evaluated the efficacy of bestatin as a novel small molecule adjuvant for inactivated FMD vaccines. Our findings showed that the FMD vaccine formulated with bestatin enhanced early, intermediate-, and particularly long-term immunity in experimental animals (mice) and target animals (pigs). Furthermore, cytokines (interferon (IFN)α, IFNß, IFNγ, and interleukin (IL)-29), retinoic acid-inducible gene (RIG)-I, and T-cell and B-cell core receptors (cluster of differentiation (CD)28, CD19, CD21, and CD81) markedly increased in the group that received the FMD vaccine adjuvanted with bestatin in pigs compared with the control. These results indicate the significant potential of bestatin to improve the efficacy of inactivated FMD vaccines in terms of immunomodulatory function for the simultaneous induction of potent cellular and humoral immune response and a long-lasting memory response.

The role of zinc sulfate in enhancing cellular and humoral immune responses to foot-and-mouth disease vaccine.

Foot-and-mouth disease (FMD) is a rapidly propagating infectious disease of cloven-hoofed animals, especially cattle and pigs, affecting the productivity and profitability of the livestock industry. Presently, FMD is controlled and prevented using vaccines; however, conventional FMD vaccines have several disadvantages, including short vaccine efficacy, low antibody titers, and safety issues in pigs, indicating the need for further studies. Here, we evaluated the efficacy of a novel bivalent vaccine containing zinc sulfate as an immunostimulant and FMD type O and A antigens (O PA2 and A YC, respectively) against FMD virus in mice and pigs. Zinc sulfate induced cellular immunity in murine peritoneal exudate cells (PECs) and porcine peripheral blood mononuclear cells (PBMCs) by increasing IFNγ secretion. Additionally, FMD vaccine containing O PA2 and A YC antigens and zinc sulfate induced early, mid-, and long-term immune responses in mice and pigs, and enhanced cellular and humoral immunity by regulating the expression of pathogen recognition receptors (PRRs), transcription factors, co-stimulatory molecules, and cytokines in porcine PBMCs from vaccinated pigs. Overall, these results indicated that the novel immunostimulant zinc sulfate induced potent cellular and humoral immune responses by stimulating antigen-presenting cells (APCs) and T and B cells, and enhanced long-term immunity by promoting the expression of co-stimulatory molecules. These outcomes suggest that zinc sulfate could be used as a novel vaccine immunostimulant for difficult-to-control viral diseases, such as African swine fever (ASF) or COVID-19.

Inhibition of matrix metalloproteinase-13 expression in IL-1ß-treated articular chondrocytes by a steroidal saponin, spicatoside A, and its cellular mechanisms of action.

Matrix metalloproteinase-13 (MMP-13) plays a critical role in degrading major collagens in human cartilage under some pathological conditions such as osteoarthritis. To establish the therapeutic potential against cartilage degradation, the effects of 12 naturally-occurring triterpenoids and steroids on MMP-13 induction were examined in the human chondrocyte cell line, SW1353. They included coreanoside F1, suavissimoside R1, spicatoside A, 25(S)-ruscogenin, methyl protogracillin, hederagenin, loniceroside A, loniceroside B, loniceroside C, smilaxin A, smilaxin C, and ursolic acid. Among these, only spicatoside A and 25(S)-ruscogenin were found to inhibit MMP-13 expression in IL-1ß-treated SW1353 cells at a pharmacologically-relevant concentration of 10 µM. These effects were also supported by the finding that spicatoside A (20 µM) reduced glycosaminoglycan release from IL-1α-treated rabbit joint cartilage culture to some degree. When the cellular mechanisms of action of spicatoside A in MMP-13 inhibition were investigated, the blocking point was not found among the MMP-13 signaling molecules examined such as mitogen-activated protein kinases, activator protein-1, and nuclear transcription factor-κB. Instead, spicatoside A was found to reduce MMP-13 mRNA stability. All of these findings suggest that spicatoside A and 25(S)-ruscogenin have a therapeutic potential for protecting against cartilage breakdown in arthritic disorders.