Short-Chain Fatty Acids Alleviate Vancomycin-Caused Humoral Immunity Attenuation in Rabies-Vaccinated Mice by Promoting the Generation of Plasma Cells via Akt-mTOR Pathway.

Mounting evidence suggests that gut microbial composition and its metabolites, including short-chain fatty acids (SCFAs), have beneficial effects in regulating host immunogenicity to vaccines. However, it remains unknown whether and how SCFAs improve the immunogenicity of the rabies vaccine. In this study, we investigated the effect of SCFAs on the immune response to rabies vaccine in vancomycin (Vanco)-treated mice and found that oral gavage with butyrate-producing bacteria (C. butyricum) and butyrate supplementation elevated RABV-specific IgM, IgG, and virus-neutralizing antibodies (VNAs) in Vanco-treated mice. Supplementation with butyrate expanded antigen-specific CD4+ T cells and IFN-γ-secreting cells, augmented germinal center (GC) B cell recruitment, promoted plasma cells (PCs) and RABV-specific antibody-secreting cells (ASCs) generation in Vanco-treated mice. Mechanistically, butyrate enhanced mitochondrial function and activated the Akt-mTOR pathway in primary B cells isolated from Vanco-treated mice, ultimately promoting B lymphocyte-induced maturation protein-1 (Blimp-1) expression and CD138+ PCs generation. These results highlight the important role of butyrate in alleviating Vanco-caused humoral immunity attenuation in rabies-vaccinated mice and maintaining host immune homeostasis. IMPORTANCE The gut microbiome plays many crucial roles in the maintenance of immune homeostasis. Alteration of the gut microbiome and metabolites has been shown to impact vaccine efficacy. SCFAs can act as an energy source for B-cells, thereby promoting both mucosal and systemic immunity in the host by inhibiting HDACs and activation of GPR receptors. This study investigates the impact of orally administered butyrate, an SCFA, on the immunogenicity of rabies vaccines in Vanco-treated mice. The results showed that butyrate ameliorated humoral immunity by facilitating the generation of plasma cells via the Akt-mTOR in Vanco-treated mice. These findings unveil the impact of SCFAs on the immune response of the rabies vaccine and confirm the crucial role of butyrate in regulating immunogenicity to rabies vaccines in antibiotic-treated mice. This study provides a fresh insight into the relationship of microbial metabolites and rabies vaccination.

Fibroblast growth factor 21 mitigates lupus nephritis progression via the FGF21/Irgm 1/NLRP3 inflammasome pathway.

As an endocrine cytokine, fibroblast growth factor 21 (FGF21) exhibits anti-inflammatory properties. With the development of lupus nephritis (LN), which is tightly related to pathogenic factors, including inflammation and immune cell dysregulation, we explored the impact of Fibroblast Growth Factor 21 (FGF21) as well as its underlying mechanism. We induced an in vivo LN model using pristane in both wild-type C57BL/6 and FGF21 knockout (FGF21-/-) mice. LN serum obtained from 32-week-old wild-type LN mice was used to stimulate RAW264.7 and human renal tubular epithelial (HK-2) cells to mimic an in vitro LN model. Moreover, our findings revealed that FGF21-/- mice showed more severe kidney injury compared to wild-type mice, as evidenced by increased levels of renal function markers, inflammatory factors, and fibrosis markers. Notably, exogenous administration of FGF21 to wild-type LN mice markedly mitigated these adverse effects. Additionally, we used tandem mass tag (TMT)-based quantitative proteomics to detect differentially expressed proteins following FGF21 treatment. Results indicated that 121 differentially expressed proteins influenced by FGF21 were involved in biological processes such as immune response and complement activation. Significantly upregulated protein Irgm 1, coupled with modulated inflammatory response, appeared to contribute to the beneficial effects of FGF21. Furthermore, Western blot analysis demonstrated that FGF21 upregulated Irgm 1 while inhibiting nucleotide-binding oligomerization domain-like receptors family pyrin domain including 3 (NLRP3) inflammasome expression. Silencing Irgm 1, in turn, reversed FGF21's inhibitory effect on NLRP3 inflammasome. In summary, FGF21 can potentially alleviate pristane-induced lupus nephritis in mice, possibly through the FGF21/Irgm 1/NLRP3 inflammasome pathway.

A broadly applicable protein-polymer adjuvant system for antiviral vaccines.

Although protein subunit vaccines generally have acceptable safety profiles with precise antigenic content, limited immunogenicity can lead to unsatisfactory humoral and cellular immunity and the need for vaccine adjuvants and delivery system. Herein, we assess a vaccine adjuvant system comprising Quillaja Saponaria-21(QS-21) and cobalt porphyrin polymeric micelles that enabling the display of His-tagged antigen on its surface. The nanoscale micelles promote antigen uptake and dendritic cell activation to induce robust cytotoxic T lymphocyte response and germinal center formation. Using the recombinant protein antigens from influenza A and rabies virus, the micelle adjuvant system elicited robust antiviral responses and protected mice from lethal challenge. In addition, this system could be combined with other antigens to induce high titers of neutralizing antibodies in models of three highly pathogenic viral pathogens: Ebola virus, Marburg virus, and Nipah virus. Collectively, our results demonstrate this polymeric micelle adjuvant system can be used as a potent nanoplatform for developing antiviral vaccine countermeasures that promote humoral and cellular immunity.

Cadmium induces apoptosis by miR-9-5p targeting PTEN and regulates the PI3K/AKT pathway in the piglet adrenal gland.

Cadmium (Cd) is an environmental pollutant that can cause endocrine organ damage. To explore the effect of subacute CdCl2 exposure on piglet adrenal gland tissue and its mechanism based on the establishment of this model, bioinformatics, TUNEL assay, western blot (WB), and qRT-PCR methods were used to detect related indicators. The results showed that after Cd exposure, antioxidant enzymes decreased, heat shock protein increased, and miR-9-5p-gene of phosphatase and tensin homolog (PTEN) upregulates the phosphatidylinositol-3-kinase (PI3K/AKT) pathway. After this pathway was activated, the expression of the apoptosis-related factors cysteinyl aspartate-specific proteinase 3 and 9 (caspase 3 and 9), B-cell lymphoma-2-associated X (BAX) was increased sharply, and the expression of B-cell lymphoma-2 (BCL2) was significantly decreased. The changes in these indicators indicate that Cd exposure induces apoptosis and causes tissue damage in the adrenal gland of piglets. This study aims to reveal the toxic effects of CdCl2 in animals and will provide new ideas for the toxicology of Cd.