Biology subjects

Mak, J. Y.

Publications and source records attributed to Mak, J. Y..

3 recordsLinked to original sources

bioRxiv2026

Specific targeting of MR1-antigen complexes using nanobodies

T cell receptor mimic (TCRm) antibodies and nanobodies that specifically bind peptide-HLA complexes have great therapeutic potential, as they can target polymorphic HLA on tumour cells furnishing peptides derived from tumour-associated antigens. MR1 is an MHC class-I-like molecule that exhibits limited polymorphism that binds and presents conserved metabolites, such as 5-OP-RU, derived from microbial riboflavin biosynthesis. Whether antibodies targeting such MR1-5-OP-RU complexes can be generated remains unclear. Using yeast display technology and in vitro affinity maturation, a nanobody with high affinity and fine specificity toward MR1-5-OP-RU complex was generated. These nanobodies bind both mouse and human MR1-5-OP-RU and inhibited MAIT cell responses to 5-OP-RU in vitro and in vivo demonstrating therapeutic potential. Moreover, we provide a molecular basis underpinning the fine specificity of these nanobodies, solving the crystal structures of MR1 in complex with either 5-OP-RU or Ac-6-FP. Here, the nanobody co-bound MR1 and 5-OP-RU, akin to a TCRm antibody. Moreover, we engineer bispecific antibodies targeting both MR1-5-OP-RU and CD3, that drive broad T cell killing of bacterially-infected cells as well as tumour cells treated with 5-OP-RU, thereby providing proof-of-principle for targeting the MR1 molecule with with TCRm-based nanobodies. One Sentence SummaryWe report the development of a nanobody targeting MR1-5-OP-RU complex and demonstrate its utility to modulate MAIT cells responses, and as a bispecific engager.

immunology↗

bioRxiv2025

Restoration of MAIT cell function in healthcare-associated bacterial infections supports recovery of carbapenem efficacy against resistant bacteria

Antimicrobial resistance (AMR) presents a major clinical challenge to patients with healthcare-associated infections (HAIs), particularly among immunocompromised individuals and patients with comoribidites, who often exhibit an impaired mucosa-associated invariant T (MAIT) cell pool. MAIT cells are innate-like T cells enriched in mucosal tissues, possess potent antibacterial activity, and restoration of their function may offer a host-directed strategy against drug-resistant pathogens. We evaluated how stimulation with cognate antigen in combination with various cytokines, modulates MAIT cell cytotoxicity and enhances carbapenem activity. Under optimal conditions, MAIT cells exhibited increased expression of antimicrobial cytolytic proteins and efficiently killed cells pulsed with MAIT cell antigen. IL-15 or IL-2 plus IL-7 were particularly effective in promoting polyfunctional cytotoxic responses. Secretomes from cytokine-stimulated MAIT cells restored the activity of imipenem against engineered E. coli expressing the clinically relevant carbapenemases blaNDM-1, blaKPC-2, and blaOXA-48, strongly reducing bacterial growth, viability, and metabolic activity. Notably, IL-2 plus IL-7 stimulation enabled expansion and functional restoration of MAIT cells from HAI patients, whose baseline MAIT cell numbers and responses were diminished. These findings demonstrate that tailored stimulation can reinvigorate MAIT cell effector function and augment antibiotic efficacy, supporting a role for MAIT cells in adjunct immunotherapeutic strategy to combat AMR in vulnerable patient populations. Category of manuscript: Research Article.

immunology↗

bioRxiv2017

Legionella protection and vaccination mediated by Mucosal Associated Invariant T (MAIT) cells

Mucosal associated invariant T (MAIT) cells recognize conserved microbial metabolites from riboflavin synthesis. Striking evolutionary conservation and pulmonary abundance implicate them in antibacterial host defense, yet their roles in protection against clinically significant pathogens are unknown. Murine Legionella infection induced MR1-dependent MAIT cell activation and rapid pulmonary accumulation of MAIT cells associated with immune protection detectable in fully immunocompetent host animals. MAIT cell protection was more evident in mice lacking CD4+ cells, whilst profoundly immunodeficient RAG2-/-{gamma}C-/- mice were substantially rescued from uniformly lethal Legionella infection by adoptively-transferred MAIT cells. This protection was dependent on MR1, IFN-{gamma} and GM-CSF, but not IL-17, TNF- or perforin. Protection was enhanced and observed earlier post-infection in mice that were Ag-primed to boost MAIT cells before infection. Our findings define a significant role for MAIT cells in protection against a major human pathogen and indicate a potential role for vaccination to enhance MAIT cell immunity.

immunology↗