MIP3α-Rel Mtb intranasal DNA vaccination induces reactive T-cell infiltration into the lungs in mice and macaques.

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is the leading cause of mortality due to a single infectious organism. While generally curable, TB requires a lengthy and complex antibiotic regimen, due in large part to bacteria that can shift to a persistent state in the presence of antibiotic pressure. Rel Mtb is the primary enzyme regulating the stringent response, which contributes to the metabolic shift of Mtb to a persistent state. Targeting Rel Mtb with a vaccine to eliminate persistent bacteria through the induction of Rel Mtb -specific T-cell immunity in combination with antibiotics to kill dividing bacteria has shown promise in model systems. In a mouse model of Mtb infection, a vaccine created by genetically fusing rel Mtb to the chemokine macrophage inflammatory protein 3α ( MIP3 α), a ligand for the CC chemokine receptor type 6 (CCR6) present on immature dendritic cells, has been shown to enhance T-cell responses and accelerate eradication of infection in mouse models compared to a vaccine lacking the chemokine component. In this study, immunogenicity studies in the mouse and rhesus macaque models provide evidence that intranasal administrations of the DNA form of the MipRel vaccine led to enhanced lung infiltration of T cells after a series of immunizations. Furthermore, despite similar T-cell immunity seen in PBMCs between MipRel and Rel vaccinations, lung and bronchoalveolar lavage cell samples are more enriched for cytokine-secreting T cells in MipRel groups compared to Rel groups. We conclude that intranasal immunization with a MIP-3α fusion vaccine represents a novel strategy for use of a simple DNA vaccine formulation to elicit T-cell immune responses within the respiratory tract. That this formulation is immunogenic in a non-human primate model historically viewed as poorly responsive to DNA vaccines indicates the potential for clinical application in the treatment of Mtb infection, with possible application to other respiratory pathogens. Future studies will further characterize the protective effect of this vaccination platform.

Therapeutic DNA Vaccine Targeting Mycobacterium tuberculosis Persisters Shortens Curative Tuberculosis Treatment.

Mycobacterium tuberculosis ( Mtb) is one of the leading infectious causes of death worldwide. There is no available licensed therapeutic vaccine that shortens active tuberculosis (TB) disease drug treatment and prevents relapse, despite the World Health Organization's calls. Here, we show that an intranasal DNA vaccine containing a fusion of the stringent response rel Mtb gene with the gene encoding the immature dendritic cell-targeting chemokine, MIP-3α/CCL20, shortens the duration of curative TB treatment in immunocompetent mice. Compared to the first-line regimen for drug-susceptible TB alone, our novel adjunctive vaccine induced greater Rel Mtb -specific T-cell responses associated with optimal TB control in spleen, blood, lungs, mediastinal lymph nodes, and bronchoalveolar lavage (BAL) fluid. These responses were sustained, if not augmented, over time. It also triggered more effective dendritic cell recruitment, activation, and colocalization with T cells, implying enhanced crosstalk between innate and adaptive immunity. Moreover, it potentiated a 6-month TB drug-resistant regimen, rendering it effective across treatment regimens, and also showed promising results in CD4+ knockout mice, perhaps due to enhanced Rel-specific CD8+ T-cell responses. Notably, our novel fusion vaccine was also immunogenic in nonhuman primates, the gold standard animal model for TB vaccine studies, eliciting antigen-specific T-cell responses in blood and BAL fluid analogous to those observed in protected mice. Our findings have critical implications for therapeutic TB vaccine clinical development in immunocompetent and immunocompromised populations and may serve as a model for defining immunological correlates of therapeutic vaccine-induced protection. One sentence summary: A TB vaccine shortens curative drug treatment in mice by eliciting strong TB-protective immune responses and induces similar responses in macaques.

A SARS-CoV-2 RBD vaccine fused to the chemokine MIP-3α elicits sustained murine antibody responses over 12 months and enhanced lung T-cell responses.

Background: Previous studies have demonstrated enhanced efficacy of vaccine formulations that incorporate the chemokine macrophage inflammatory protein 3α (MIP-3α) to direct vaccine antigens to immature dendritic cells. To address the reduction in vaccine efficacy associated with a mutation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mutants, we have examined the ability of receptor-binding domain vaccines incorporating MIP-3α to sustain higher concentrations of antibody when administered intramuscularly (IM) and to more effectively elicit lung T-cell responses when administered intranasally (IN). Methods: BALB/c mice aged 6-8 weeks were immunized intramuscularly or intranasally with DNA vaccine constructs consisting of the SARS-CoV-2 receptor-binding domain alone or fused to the chemokine MIP-3α. In a small-scale (n = 3/group) experiment, mice immunized IM with electroporation were followed up for serum antibody concentrations over a period of 1 year and for bronchoalveolar antibody levels at the termination of the study. Following IN immunization with unencapsulated plasmid DNA (n = 6/group), mice were evaluated at 11 weeks for serum antibody concentrations, quantities of T cells in the lungs, and IFN-γ- and TNF-α-expressing antigen-specific T cells in the lungs and spleen. Results: At 12 months postprimary vaccination, recipients of the IM vaccine incorporating MIP-3α had significantly, approximately threefold, higher serum antibody concentrations than recipients of the vaccine not incorporating MIP-3α. The area-under-the-curve analyses of the 12-month observation interval demonstrated significantly greater antibody concentrations over time in recipients of the MIP-3α vaccine formulation. At 12 months postprimary immunization, only recipients of the fusion vaccine had concentrations of serum-neutralizing activity deemed to be effective. After intranasal immunization, only recipients of the MIP-3α vaccine formulations developed T-cell responses in the lungs significantly above those of PBS controls. Low levels of serum antibody responses were obtained following IN immunization. Conclusion: Although requiring separate IM and IN immunizations for optimal immunization, incorporating MIP-3α in a SARS-CoV-2 vaccine construct demonstrated the potential of a stable and easily produced vaccine formulation to provide the extended antibody and T-cell responses that may be required for protection in the setting of emerging SARS-CoV-2 variants. Without electroporation, simple, uncoated plasmid DNA incorporating MIP-3α administered intranasally elicited lung T-cell responses.

TGF-ß2 enhances expression of equine bone marrow-derived mesenchymal stem cell paracrine factors with known associations to tendon healing.

BACKGROUND: Mesenchymal stem cells (MSCs) secrete paracrine factors and extracellular matrix proteins that contribute to their ability to support tissue healing and regeneration. Both the transcriptome and the secretome of MSCs can be altered by treating the cells with cytokines, but neither have been thoroughly investigated following treatment with the specific cytokine transforming growth factor (TGF)-ß2. METHODS: RNA-sequencing and western blotting were used to compare gene and protein expression between untreated and TGF-ß2-treated equine bone marrow-derived MSCs (BM-MSCs). A co-culture system was utilized to compare equine tenocyte migration during co-culture with untreated and TGF-ß2-treated BM-MSCs. RESULTS: TGF-ß2 treatment significantly upregulated gene expression of collagens, extracellular matrix molecules, and growth factors. Protein expression of collagen type I and tenascin-C was also confirmed to be upregulated in TGF-ß2-treated BM-MSCs compared to untreated BM-MSCs. Both untreated and TGF-ß2-treated BM-MSCs increased tenocyte migration in vitro. CONCLUSIONS: Treating equine BM-MSCs with TGF-ß2 significantly increases production of paracrine factors and extracellular matrix molecules important for tendon healing and promotes the migration of tenocytes in vitro.