Biology subjects

Lewinsohn, D. A.

Publications and source records attributed to Lewinsohn, D. A..

6 recordsLinked to original sources

bioRxiv2026

Human memory CD4+ T cells recognize non-infected macrophage bystanders exposed to Mycobacterium tuberculosis-infected cells

Control of Mycobacterium tuberculosis (Mtb) infection requires CD4+ T cell recognition of infected macrophages. However, T cells also colocalize with non-infected macrophages in granulomas. We investigated whether these bystander macrophages present Mtb antigens and shape human CD4+ T cell responses. Using ex vivo co-culture systems, non-infected monocyte-derived macrophages (MDMs) were exposed to Mtb-infected MDMs or infection-conditioned supernatants before co-incubation with autologous memory CD4+ T cells from individuals with latent Mtb infection (LTBI). Bystander macrophages activated memory CD4+ T cells through MHC-II-dependent antigen presentation. Single-cell T cell receptor (TCR) sequencing and TCR-transduced reporter cell lines identified Mtb-specific clonotypes recognizing both infected and bystander macrophages, as well as clonotypes preferentially recognizing infected cells. Strikingly, a subset of TCRs recognized infected but not bystander macrophages. Antigen transfer occurred through soluble Mtb proteins rather than extracellular vesicles. Compared with responses to infected macrophages, bystander macrophages induced attenuated effector responses. These findings reveal antigen-specific recognition of bystander macrophages and suggest that antigens preferentially presented by infected cells may inform TB vaccine design.

immunology↗

bioRxiv2026

Lung Resident T Cells Across the Spectrum of TB Infection and Disease

Tuberculosis (TB) remains the leading infectious cause of death worldwide, yet immunological protection against Mycobacterium tuberculosis (Mtb) remain poorly understood. We performed integrated single-cell transcriptomics and functional T-cell cloning on paired bronchoalveolar lavage (BAL) and peripheral blood samples from those exposed to TB, using IGRA and PET-CT to study potentially protective responses across the spectrum of TB infection/disease. Recent Mtb exposure alone was sufficient to remodel the pulmonary T-cell compartment. Longitudinal follow-up demonstrated that all participants who progressed to active TB had baseline PET-CT abnormalities, showing that PET-CT scan can be used to find those at high risk of progression. Furthermore, those who were PET-positive, but did not progress to active TB provide a natural model for protection, and exhibited enrichment of pulmonary cytotoxic CD8-associated T cells, identifying a candidate protective immune program. TAR-seq identified a discrete population of clonally expanded Mtb-responsive T cells and enabled direct linkage of antigen-responsive TCRs to transcriptional state through T cell cloning. Functional T-cell cloning further established a framework connecting antigen specificity, TCR sequence, and pulmonary cell state. Together, these findings provide a comprehensive atlas of human pulmonary T-cell immunity across the spectrum of TB, identify pulmonary immune features associated with durable control of infection, and establish an integrated platform for defining protective T-cell responses to inform next-generation TB vaccine development.

immunology↗

bioRxiv2026

Antigenic stimulation in conjunction with cytokine is required for mediating IL-17A production in human MAIT cells

Mucosal-associated invariant T (MAIT) cells are donor unrestricted T cells capable of both antigen-specific adaptive responses and cytokine driven innate-like functions. Although human MAIT cells uniformly express ROR{gamma}t and IL23R, they generally produce IFN-{gamma}, and only a small fraction produces IL-17. Recent studies show that combined TCR and cytokine stimulation can elicit functional heterogeneity in blood-derived MAIT cells. Here, we investigate the role of IL-23/IL-23R signaling in mediating the function and transcriptional profiles of lung MAIT cell clones. We demonstrate that BAL-derived lung MAIT cell clones exhibit distinct cytokine profiles and variable IL23R expression. Short-term IL-23 stimulation triggers clone-specific transcriptional programs and IL23R-dependent upregulation of type 17-associated genes. Prolonged conditioning of lung MAIT cell clones with TCR (5-OP-RU) and cytokine (IL-23) stimulation induces stable IL-17A production along with unique transcriptional changes. TCR + IL-23 conditioning alone upregulates clone-specific and shared cytoskeletal/structural gene programs, whereas subsequent PMA/Ionomycin stimulation further induces IL-12 family signaling and metabolic genes. Together, these findings demonstrate that IL23R expression and TCR signaling are required for IL-17A production, highlighting that these conditions may be met in tissue environments where MR1-specific antigens and proinflammatory cytokines coexist.

immunology↗

bioRxiv2022

Delivery of loaded MR1 Monomer Results in Efficient Ligand Exchange to Host MR1 and Subsequent MR1T cell activation

MR1-restricted T cells have been implicated in microbial infections, sterile inflammation, wound healing and cancer. Similar to other antigen presentation molecules, evidence supports multiple, complementary MR1 antigen presentation pathways. To investigate ligand exchange pathways for MR1, we used MR1 monomers and tetramers loaded with 5-(2-oxopropylideneamino)-6-d-ribitylaminouracil (5-OP-RU) to deliver the antigen. Using MR1-deficient cells reconstituted with wild-type MR1 or MR1 molecules that cannot bind 5-OP-RU, we show that presentation of monomer-delivered 5-OP-RU is dependent on cellular MR1 and requires the transfer of ligand from the soluble molecule onto MR1 expressed by the antigen presenting cell. This mode of antigen delivery strengthens the evidence for post-ER ligand exchange pathways for MR1, which could represent an important avenue by which MR1 acquires antigens derived from endocytosed pathogens.

immunology↗

bioRxiv2022

Deaza-modification of MR1 ligands modulates recognition by MR1-restricted T cells

MR1-restricted T (MR1T) cells recognize microbial small molecule metabolites presented on the MHC Class I-like molecule MR1 and have been implicated in early effector responses to microbial infection. As a result, there is considerable interest in identifying chemical properties of metabolite ligands that permit recognition by MR1T cells, for consideration in therapeutic or vaccine applications. Here, we made chemical modifications to known MR1 ligands to evaluate the effect on MR1T cell activation. Specifically, we modified 6,7-dimethyl-8-D-ribityllumazine (DMRL) to generate 6,7-dimethyl-8-D-ribityldeazalumazine (DZ), and then further derivatized DZ to determine the requirements for retaining MR1 surface stabilization and agonistic properties. Interestingly, the IFN-{gamma} response toward DZ varied widely across a panel of T cell receptor (TCR)-diverse MR1T cell clones; while one clone was agnostic toward the modification, most displayed either an enhancement or depletion of IFN-{gamma} production when compared with its response to DMRL. To gain insight into a putative mechanism behind this phenomenon, we used in silico molecular docking techniques for DMRL and its derivatives and performed molecular dynamics simulations of the complexes. In assessing the dynamics of each ligand in the MR1 pocket, we found that DMRL and DZ exhibit differential dynamics of both the ribityl moiety and the aromatic backbone, which may contribute to ligand recognition. Together, our results support an emerging hypothesis for flexibility in MR1:ligand-MR1T TCR interactions and enable further exploration of the relationship between MR1:ligand structures and MR1T cell recognition for downstream applications targeting MR1T cells.

immunology↗

bioRxiv2019

Postnatal expansion, maturation and functionality of MR1 T cells in humans

MR1-restricted T (MR1T) cells are defined by their recognition of metabolite antigens presented by the monomorphic MHC class 1-related molecule, MR1, the most highly conserved MHC class I related molecule in mammalian species. Mucosal-associated invariant T (MAIT) cells are the predominant subset of MR1T cells expressing an invariant TCR -chain, TRAV1-2. These cells comprise a T cell subset that recognizes and mediates host immune responses to a broad array of microbial pathogens, including Mycobacterium tuberculosis. Here, we sought to characterize development of circulating human MR1T cells as defined by MR1-5-OP-RU tetramer labelling and of the TRAV1-2+ MAIT cells defined by expression of TRAV1-2 and high expression of CD26 and CD161 (TRAV1-2+CD161++CD26++ cells). We analysed postnatal expansion, maturation and functionality of peripheral blood MR1-5-OP-RU tetramer+ MR1T cells in cohorts from three different geographic settings with different tuberculosis (TB) vaccination practices, levels of exposure to and infection with M. tuberculosis. Early after birth, frequencies of MR1-5-OP-RU tetramer+ MR1T cells increased rapidly by several fold. This coincided with the transition from a predominantly CD4+ and TRAV1-2- population in neonates, to a predominantly TRAV1-2+CD161++CD26++ CD8+ population. We also observed that tetramer+ MR1T cells that expressed TNF upon mycobacterial stimulation were very low in neonates, but increased [~]10-fold in the first year of life. These functional MR1T cells in all age groups were MR1-5-OP-RU tetramer+TRAV1-2+ and highly expressed CD161 and CD26, markers that appeared to signal phenotypic and functional maturation of this cell subset. This age-associated maturation was also marked by the loss of naive T cell markers on tetramer+ TRAV1-2+ MR1T cells more rapidly than tetramer+TRAV1-2- MR1T cells and non-MR1T cells. These data suggest that neonates have infrequent populations of MR1T cells with diverse phenotypic attributes; and that exposure to the environment rapidly and preferentially expands the MR1-5-OP-RU tetramer+TRAV1-2+ population of MR1T cells, which becomes the predominant population of functional MR1T cells early during childhood.

immunology↗