A Convenient Synthetic Method to Improve Immunogenicity of Mycobacterium tuberculosis Related T-Cell Epitope Peptides

The Role and Potential Application of IL-12 in the Immune Regulation of Tuberculosis

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a significant global health challenge, affecting millions annually and leading to substantial mortality, particularly in developing countries. The pathogen's ability to persist latently and evade host immunity, combined with the emergence of drug-resistant strains, underscores the need for innovative therapeutic strategies. This review highlights the crucial role of interleukin-12 (IL-12) in coordinating immune responses against TB, focusing on its potential as an immunotherapy target. IL-12, a key Th1 cytokine, enhances cellular immunity by promoting Th1 cell differentiation and IFN-γ production, vital for Mtb clearance. By stimulating cytotoxic T lymphocytes and establishing immune memory, IL-12 supports robust host defense mechanisms. However, the complexity of IL-12 biology, including its roles in pro-inflammatory and regulatory pathways, necessitates a nuanced understanding for effective therapeutic use. Recent studies have shown how IL-12 impacts T cell synapse formation, exosome-mediated bystander activation, and interactions with other cytokines in shaping T cell memory. Genetic defects in the IL-12/IFN-γ axis link to susceptibility to mycobacterial diseases, highlighting its importance in TB immunity. The review also addresses challenges like cytokine imbalances seen in TNF-α/IFN-γ synergy, which exacerbate inflammation, and the implications for IL-12-based interventions. Research into modulating IL-12, including its use as an adjuvant and in recombinant vaccines, promises improved TB treatment outcomes and vaccine efficacy. The review concludes by stressing the need for continued investigation into IL-12's molecular mechanisms towards precision immunotherapies to combat TB and its complications.

Optimizing lipopeptide bioactivity: The impact of non-ionic surfactant dressing

The aim of the research is to increase the applicability of lipopeptides as drugs. To this end, non-ionic triblock copolymers, namely poloxamers, were applied. The physico-chemical properties of poloxamers vary depending on the length of the blocks. In our study, we experimented with different types and systematically investigated the variation of the critical micelle concentration (CMC) of poloxamers at 25 and 37 °C in different media. In addition, the cytotoxicity of the different poloxamer micelles on three different cell lines was evaluated, and based on the results, Plur104, Plur123, and Plur127 were selected. Fatty acid elongated derivatives of a short antibacterial peptide (pL1), a medium-sized anticancer peptide (pCM15), and a branched-chain vaccine antigen (pATIPC) were used as lipopeptide models, and their formulations with the selected poloxamers were investigated. The solubility and homogeneity of the lipopeptides were significantly increased, and dynamic light scattering (DLS) measurements showed the formation of small particles of around 20 nm, which were well reproducible and storable. Similar homogenous micelle formation was observed after freeze-drying and reconstitution with water. The pL1 lipopeptide, formulated with the selected poloxamers, exhibited enhanced antibacterial activity with significantly reduced haemolytic side effects. The pCM15 peptide, when incorporated into poloxamer micelles, showed significantly enhanced cytotoxicity against tumor cells. Additionally, the internalization rate of poloxamer-formulated pATIPC peptide by antigen-presenting model cells exceeded that of the unformulated peptide. Our results demonstrate the potential of poloxamers as promising tools for the formulation of lipopeptides and for the optimization of their selectivity.

A novel multistage antigens ERA005f confer protection against Mycobacterium tuberculosis by driving Th-1 and Th-17 type T cell immune responses

Introduction

Tuberculosis (TB) is a major threat to human health. In 2021, TB was the second leading cause of death after COVID-19 among infectious diseases. The Bacillus Calmette-Guérin vaccine (BCG), the only licensed TB vaccine, is ineffective against adult TB. Therefore, there is an urgent need to develop new effective vaccines.

Methods

In this study, we developed a novel multistage subunit vaccine (ERA005f) comprising various proteins expressed in metabolic states, based on three immunodominant antigens (ESAT-6, Rv2628, and Ag85B). We utilized the E. coli prokaryotic expression system to express ERA005f and subsequently purified the protein using nickel affinity chromatography and anion exchange. Immunogenicity and protective efficacy of ERA005f and ERA005m were evaluated in BALB/c mice.

Results

ERA005f was consistently expressed as an inclusion body in a prokaryotic expression system, and a highly pure form of the protein was successfully obtained. Both ERA005f and ERA005m significantly improved IgG titers in the serum. In addition, mice immunized with ERA005f and ERA005m generated higher titers of antigen-specific IgG2a than the other groups. Elispot results showed that, compared with other groups, ERA005f increased the numbers of IFN-γ-secreting and IL-4-secreting T cells, especially the number of IFN-γ-secreting T cells. Meanwhile, ERA005f induced a higher number of IFN-γ+ T lymphocytes than ERA005m did. In addition, ERA005f improved the expression of cytokines, including IFN-γ, IL-12p70, TNF-α, IL-17, and GM-CSF and so on. Importantly, both ERA005f and ERA005m significantly inhibited the growth of Mtb.

Conclusion

The novel multistage antigen ERA005f elicited a strong antigen-specific humoral response and Th-1 and Th-17 cell-mediated immunity in mice. Meanwhile, it can effectively inhibit H37Rv growth in vitro, and represents a correlate of protection in vivo, indicating that ERA005f may exhibit excellent protective efficacy against Mycobacterium tuberculosis H37Rv infection. Our study suggests that ERA005f has the potential to be a promising multistage tuberculosis vaccine candidate.

Design and Characterization of a Multistage Peptide-Based Vaccine Platform to Target Mycobacterium tuberculosis Infection

The complex immunopathology ofMycobacterium tuberculosis(Mtb) is one of the main challenges in developing a novel vaccine against this pathogen, particularly regarding eliciting protection against both active and latent stages. Multistage vaccines, which contain antigens expressed in both phases, represent a promising strategy for addressing this issue, as testified by the tuberculosis vaccine clinical pipeline. Given this approach, we designed and characterized a multistage peptide-based vaccine platform containing CD4+ and CD8+ T cell epitopes previously validated for inducing a relevant T cell response against Mtb. After preliminary screening, CFP10 (32-39), GlfT2 (4-12), HBHA (185-194), and PPE15 (1-15) were selected as promising candidates, and we proved that the PM1 pool of these peptides triggered a T cell response in Mtb-sensitized human peripheral blood mononuclear cells (PBMCs). Taking advantage of the use of thiol-maleimide chemoselective ligation, we synthesized a multiepitope conjugate (Ac-CGHP). Our results showed a structure-activity relationship between the conjugation and a higher tendency to fold and assume an ordered secondary structure. Moreover, the palmitoylated conjugate (Pal-CGHP) comprising the same peptide antigens was associated with an enhanced cellular uptake in human and murine antigen-presenting cells and a better immunogenicity profile. Immunization study, conducted in BALB/c mice, showed that Pal-CGHP induced a significantly higher T cell proliferation and production of IFNγ and TNFα over PM1 formulated in the Sigma Adjuvant System.

Peptide-Based Vaccines for Tuberculosis

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. As a result of the coronavirus disease 2019 (COVID-19) pandemic, the global TB mortality rate in 2020 is rising, making TB prevention and control more challenging. Vaccination has been considered the best approach to reduce the TB burden. Unfortunately, BCG, the only TB vaccine currently approved for use, offers some protection against childhood TB but is less effective in adults. Therefore, it is urgent to develop new TB vaccines that are more effective than BCG. Accumulating data indicated that peptides or epitopes play essential roles in bridging innate and adaptive immunity and triggering adaptive immunity. Furthermore, innovations in bioinformatics, immunoinformatics, synthetic technologies, new materials, and transgenic animal models have put wings on the research of peptide-based vaccines for TB. Hence, this review seeks to give an overview of current tools that can be used to design a peptide-based vaccine, the research status of peptide-based vaccines for TB, protein-based bacterial vaccine delivery systems, and animal models for the peptide-based vaccines. These explorations will provide approaches and strategies for developing safer and more effective peptide-based vaccines and contribute to achieving the WHO's End TB Strategy.

Peptides-Based Vaccine MP3RT Induced Protective Immunity Against Mycobacterium Tuberculosis Infection in a Humanized Mouse Model

Background

Tuberculosis (TB) is still a global infectious disease that seriously threatens human beings. The only licensed TB vaccine Bacille Calmette-Guérin (BCG)’s protective efficacy varies significantly among populations and regions. It is very urgent to develop more effective vaccines.

Methods

In this study, eleven candidate proteins of Mycobacterium tuberculosis were selected to predict peptides with high-affinity binding capacity for the HLA-DRB1*01:01 molecule. The immunodominant peptides were identified with the enzyme-linked immunospot assay (ELISPOT) and linked in silico to result in a novel polypeptide vaccine in Escherichia coli cells. The vaccine’s protective efficacy was evaluated in humanized and wild-type C57BL/6 mice. The potential immune protective mechanisms were explored with Enzyme-linked Immunosorbent Assay (ELISA), flow cytometry, and ELISPOT.

Results

Six immunodominant peptides screened from 50 predicted peptides were used to construct a new polypeptide vaccine named MP3RT. After challenge with M. tuberculosis, the colony-forming units (CFUs), lung lesion area, and the number of inflammatory cells in humanized mice rather than wild-type mice vaccinated with MP3RT were significantly lower than these in mice immunized with PBS. The humanized mice vaccinated with MP3RT revealed significant increases in IFN-γ cytokine production, IFN-γ⁺ T lymphocytes, CD3⁺IFN-γ⁺ T lymphocytes, and the MP3RT-specific IgG antibody.

Conclusions

Taken together, MP3RT is a promising peptides-based TB vaccine characterized by inducing high levels of IFN-γ and CD3⁺IFN-γ⁺ T lymphocytes in humanized mice. These new findings will lay a foundation for the development of peptides-based vaccines against TB.

Recent Advances in the Development of Protein- and Peptide-Based Subunit Vaccines against Tuberculosis

The World Health Organization (WHO) herald of the “End TB Strategy” has defined goals and targets for tuberculosis prevention, care, and control to end the global tuberculosis endemic. The emergence of drug resistance and the relative dreadful consequences in treatment outcome has led to increased awareness on immunization against Mycobacterium tuberculosis (Mtb). However, the proven limited efficacy of Bacillus Calmette-Guérin (BCG), the only licensed vaccine against Mtb, has highlighted the need for alternative vaccines. In this review, we seek to give an overview of Mtb infection and failure of BCG to control it. Afterward, we focus on the protein- and peptide-based subunit vaccine subtype, examining the advantages and drawbacks of using this design approach. Finally, we explore the features of subunit vaccine candidates currently in pre-clinical and clinical evaluation, including the antigen repertoire, the exploited adjuvanted delivery systems, as well as the spawned immune response.

Mycobacterium tuberculosis Rv0341 Promotes Mycobacterium Survival in In Vitro Hostile Environments and within Macrophages and Induces Cytokines Expression

Mycobacterium tuberculosis represents an ancient deadly human pathogen that can survive and multiply within macrophages. The effectors are key players for the successful pathogenesis of this bacterium. M. tuberculosis open reading frame (ORF) Rv0341, a pathogenic mycobacteria-specific gene, was found to be upregulated in macrophages isolated from human tuberculosis granuloma and inside the macrophages during in vitro infection by M. tuberculosis. To understand the exact role of this gene, we expressed the Rv0341 gene in M. smegmatis, which is a non-pathogenic Mycobacterium. We found that Rv0341 expression can alter colony morphology, reduce the sliding capability, and decrease the cell wall permeability of M. smegmatis. Furthermore, Rv0341 remarkably enhanced M. smegmatis survival within macrophages and under multiple in vitro stress conditions when compared with the control strain. Ms_Rv0341 significantly induced expression of TNF-α, IL-1β, and IL-10 compared with M. smegmatis harboring an empty vector. In summary, these data suggest that Rv0341 is one of the M. tuberculosis virulence determinants that can promote bacilli survival in harsh conditions and inside macrophages.