Tissue-resident memory T cells (TRM cells) provide rapid and superior control of localised infections. While the transcription factor Runx3 is a critical regulator of CD8 + T cell tissue residency, its expression is repressed in CD4 + T cells. Here, we show that as a direct consequence of this Runx3-deficiency, CD4 + TRM cells lack the TGFb-responsive transcriptional network that underpins the tissue residency of epithelial CD8 + TRM cells. While CD4 + TRM cell formation requires Runx1, this along with the modest expression of Runx3 in CD4 + TRM cells was insufficient to engage the TGFb-driven residency program. Ectopic expression of Runx3 in CD4 + T cells induced a TGFb-transcriptional network to promote prolonged survival, decreased tissue egress, a microanatomical redistribution towards epithelial layers and enhanced effector functionality. Thus, our results reveal distinct programming of tissue residency in CD8 + and CD4 + TRM cell subsets that is attributable to divergent Runx3 activity.

The tuberculosis (TB) vaccine bacille Calmette-Guérin (BCG) prevents disseminated childhood TB; however, it fails to protect against the more prevalent pulmonary TB. Limited understanding of the immune response to Mycobacterium tuberculosis, the causative agent of TB, has hindered development of improved vaccines. Although memory CD4 T cells are considered the main mediators of protection against TB, recent studies suggest there are other key subsets that contribute to antimycobacterial immunity. To that end, innate cells may be involved in the protective response. In this study, we investigated the primary response of innate lymphoid cells (ILCs) to BCG exposure. Using a murine model, we showed that ILCs increased in number in the lungs and lymph nodes in response to BCG vaccination. Additionally, there was significant production of the antimycobacterial cytokine IFN-γ by ILCs. As ILCs are located at mucosal sites, it was investigated whether mucosal vaccination (intranasal) stimulated an enhanced response compared to the traditional vaccination approach (intradermal or subcutaneous). Indeed, in response to intranasal vaccination, the number of ILCs, and IFN-γ production in NK cells and ILC1s in the lungs and lymph nodes, were higher than that provoked through intradermal or subcutaneous vaccination. This work provides the first evidence that BCG vaccination activates ILCs, paving the way for future research to elucidate the protective potential of ILCs against mycobacterial infection. Additionally, the finding that lung ILCs respond rigorously to mucosal vaccination may have implications for the delivery of novel TB vaccines.

A major obstacle to tuberculosis (TB)‐subunit–vaccine development has been the induction of inadequate levels of protective immunity due to the limited breadth of antigen in vaccine preparations. In this study, immunogenic mycobacterial fusion peptides Ag85B‐TB10.4 and Ag85B‐TB10.4‐Rv2660c were covalently displayed on the surface of self‐assembled polyester particles. This study investigated whether polyester particles displaying mycobacterial antigens could provide augmented immunogenicity (i.e., offer an innovative vaccine formulation) when compared with free soluble antigens. Herein, polyester particle–based particulate vaccines were produced in an endotoxin‐free Escherichia coli strain and emulsified with the adjuvant dimethyl dioctadecyl ammonium bromide. C57BL/6 mice were used to study the immunogenicity of formulated particulate vaccines. The result of humoral immunity showed the antibodies only interacted with target antigens and not with PhaC and the background proteins of the production host. The analysis of T helper 1 cellular immunity indicated that a relatively strong production of cellular immunity biomarkers, IFN‐γ and IL‐17A cytokines, was induced by particulate vaccines when compared with the respective soluble controls. This study demonstrated that polyester particles have the potential to perform as a mycobacterial antigen–delivery agent to induce augmented antigen‐specific immune responses in contrast to free soluble vaccines.—Chen, S., Sandford, S., Kirman, J. R., Rehm, B. H. A. Innovative antigen carrier system for the development of tuberculosis vaccines. FASEB J. 33, 7505–7518 (2019). http://www.fasebj.org

Synthetic subunit vaccines hold great promise to prevent infectious diseases, but they often induce only weak immune responses. Here bioengineering techniques to develop immunogenic antigen particles comprised of self‐assembling antigenic peptides are exploited. A bioparticle platform is developed to present repetitive copies of subunit antigens, which mimic the host‐pathogen surface interaction to provide enhanced immunogenicity. Herein, mycobacterial fusion proteins H4 (consisting of Ag88B‐TB10.4) and H28 (containing Ag88B‐TB10.4‐Rv2660c) are bioengineered to assemble H4 and/or H28 antigens into particulate vaccines inside an endotoxin‐free Escherichia coli strain, to serve as a novel vaccine against tuberculosis (TB). A bioprocess for particle isolation is developed. The physicochemical properties of the particles are investigated. Antigen particles formulated with the adjuvant dimethyl dioctadecyl ammonium bromide are used to subcutaneously immunize C57BL/6 mice. Both soluble and particulate vaccines elicit production of functional and specific antibodies, which only interact with target antigens and not production host cell proteins. Particulate vaccines induce strong production of interferon gamma (IFNγ) and interleukin 17A (IL17A) cytokines. When compared to soluble antigens, the antigen particle vaccines show increased immunogenicity. Overall, this study provides proof of concept that selected antigens can be engineered to self‐assemble into inclusion bodies to serve as particulate vaccines with improved immunological properties compared to the respective soluble antigens.