Biology subjects

Joller, N.

Publications and source records attributed to Joller, N..

9 recordsLinked to original sources

bioRxiv2026

Cytokine-mediated activation of exhausted T cells

CD8 T cell exhaustion during chronic infection and cancer is marked by impaired effector function and limited responsiveness to stimulation. While memory CD8 T cells can be activated TCR-independently by IL-12 and IL-18, it remains unclear whether exhausted cells, despite diminished TCR responsiveness, retain this cytokine-driven effector capacity. Here, we show that IL-12 and IL-18 stimulation induce robust IFN{gamma} production in exhausted CD8 T cells from chronic LCMV Cl13 infection, exceeding responses to antigen-specific stimulation. This activation does not result in upregulation of Tox, suggesting engagement of transcriptional circuits distinct from those promoting exhaustion. Single-cell transcriptomics revealed an innate acting T cell (TIA)-specific gene signature enriched within exhausted populations in chronic infection and tumor-infiltrating lymphocytes, particularly at the interface of intermediate and terminal exhaustion. Using heterologous Legionella pneumophila infection, we confirmed in vivo bystander responsiveness of exhausted CD8 T cells, reducing bacterial burden, highlighting their functional capacity. Our findings demonstrate that exhausted CD8 T cells retain inducible effector capacity through IL-12 and IL-18 stimulation, providing new insights into possible routes to activate exhausted T cells.

immunology↗

bioRxiv2026

Leishmaniamajor co-opts IL-7 feedback in monocytes to suppress CD4⁺ T-cell immunity

During immune responses, pro-and anti-inflammatory mechanisms must be balanced to ensure pathogen clearance while limiting tissue damage. Monocyte-derived cells contribute to both processes, yet the underlying regulatory circuits remain incompletely defined. Here, we show that a subset of PDPN+IL-7R+ monocyte-derived cells that impair effector CD4 T cell-mediated control of intracellular pathogens, and thus perpetuate the infection. Fibroblast-derived IL-7 drives this immunosuppressive program, which is up-regulated in response to IFN{gamma}. We thus uncover a cytokine-dependent feedback circuit in which elevated IFN{gamma} induces IL-7 production by fibroblasts, licensing immunosuppressive monocyte-derived cells that restrain CD4 T cell responses. This mechanism links excessive inflammation to immune suppression at the expense of pathogen control. Targeting this feedback loop may enable therapeutic strategies that enhance antimicrobial immunity while preserving tissue integrity.

immunology↗

bioRxiv2026

IL-12R signaling promotes type 1 regulatory T cell specialization by sustaining T-bet

Elucidating how regulatory T (Treg) cells specialize and acquire specific suppressive capacities is key for understanding immune regulation in autoimmunity and cancer. Although IL-12 is a key driver of Th1 differentiation, its role in Treg cells remains poorly defined. Here, we investigated whether IL-12R signaling contributes to Treg cell specialization during Th1 immune responses. We show that IL-12R{beta}2 KO Treg cells display reduced type 1 specialization following LCMV infection, resulting in impaired suppressive capacity. Mechanistically, IFN-{gamma} induces a first peak of T-bet, whereas IL-12 acts downstream to sustain T-bet through a positive feedback loop. The decreased suppressive function of IL-12R{beta}2 KO Treg cells alters effector T cell responses during both acute and chronic infections. Importantly, human Treg cells also respond to IL-12, promoting enhanced type 1 specialization. Together, these findings establish IL-12 as a critical regulator of type 1 Treg specialization and highlight the therapeutic potential of targeting this pathway. TeaserIL-12R signaling in Treg cells enables sustained T-bet expression, programing type 1 Tregs for suppression of Th1 responses.

immunology↗

bioRxiv2025

CD4 T cells acquire innate capability upon classical T cell activation

Memory T cells, a sizable compartment of the mature immune system, enable enhanced responses upon re-infection with the same pathogen. We have recently shown that virus-experienced innate acting T (TIA) cells can modulate infectious or autoimmune diseases through TCR-independent IFN-{gamma} production. However, how these cells arise remains unclear. Here, we show that CD4 TIA cells are present in various disease settings hinting towards a disease-agnostic nature. TCR stimulation and CD28 co-stimulation are sufficient to induce naive murine and human CD4 T cells to become capable of cytokine-mediated, TCR-independent IFN-{gamma} responses. In true TIA fashion, adoptive transfer of in vitro-induced TIA cells in mice yielded a TCR-independent IFN-{gamma} response during the innate phase of a Legionella pneumophila infection. Our data thus shows that CD4 TIA cells are more ubiquitous than anticipated and could therefore be involved in more settings than expected.

immunology↗

bioRxiv2025

Chronic Antigen Stimulation in Solid Tumors Induces T Cell Exhaustion and Limits Efficacy of T Cell Bispecific Therapies

T cell bispecific antibodies (TCBs) have demonstrated promising results in patients with solid tumors. However, the underlying immunological and molecular mechanisms influencing these clinical outcomes require in depth evaluation. T cell exhaustion, a state induced by prolonged antigen exposure, is known to undermine T cell-based immunotherapies, though its specific impact on TCB efficacy remains unclear. In this study, we assessed the effectiveness of TCBs on tumor-specific T cells, focusing on their functional status. Utilizing a fully immunocompetent mouse model with a solid tumor expressing an immunogenic antigen, we showed that tumor-specific T cells acquire an exhausted phenotype and fail to expand under TCB treatment. By employing both mouse and human tumor-specific T cells in vitro, our study established that chronically stimulated tumor-specific T cells show impaired response to TCB treatment. The comparison of TCB efficacy in T cell-inflamed tumors with immunogenic antigens versus non-inflamed tumors with low antigen presence in mice revealed TCB success in solid tumors is more reliant on T cell functional fitness than on their abundance before treatment. The data also indicate that solid tumors with elevated levels of both, intratumoral regulatory T cells, and T cells expressing co-inhibitory receptors, show diminished responses to TCB therapy, aligning with similar observations described in hematological cancers. These findings highlight the critical role of T cell exhaustion due to chronic antigen exposure and illustrate that exhausted tumor-specific T cells are likely not the driver population redirected by TCBs for tumor elimination. Our research highlights the importance of maintaining T cell fitness and preventing T cell exhaustion to improve TCB therapy outcomes. This may help better identify patient populations with solid tumors that could benefit from TCB treatments most in clinical settings.

cancer biology↗

bioRxiv2024

Clonally expanded IgG antibody-secreting cells preferentially target influenza nucleoprotein following homologous and heterologous infections

Infection with influenza virus remains a significant global health concern due to its ability to acquire mutations at key antigenic sites to escape antibody recognition. While germinal center (GC) and memory B cells have been well studied following influenza infection, the clonal dynamics of antibody secreting cells (ASCs), particularly those within the bone marrow (BM) niche that are responsible for serum immune protection, remain poorly understood. Here, we combine single-cell RNA (scRNA) and B cell receptor (BCR) sequencing to characterize individual ASCs following various Influenza exposure histories. We find that BM repertories are populated by highly expanded and class-switched ASCs following Influenza infection with similar transcriptional and repertoire characteristics regardless of homologous or heterologous infection histories. By combining single-cell analysis with monoclonal antibody expression and characterization, we find that a large proportion of the expanded IgG-, but not IgA-, ASC repertoire demonstrates specificity to influenza nucleoprotein (NP). Together, our data reveal the complex relationship between BM ASC repertoires, mucosal humoral immune responses, and BCR antigen specificity during influenza infection.

immunology↗

bioRxiv2023

Memory Th1 cells modulate heterologous diseases through innate function

Through immune memory, infections have a lasting effect on the host. While memory cells enable accelerated and enhanced responses upon re-challenge with the same pathogen, their impact on susceptibility to unrelated diseases is unclear. We identify a subset of memory T helper 1 (Th1) cells termed innate acting memory T (TIA) cells that originate from a viral infection and produce IFN-{gamma} with innate kinetics upon heterologous challenge in vivo. Activation of memory TIA cells is induced in response to IL-12 in combination with IL-18 or IL-33 but is TCR-independent. Rapid IFN-{gamma} production by memory TIA cells is protective in subsequent heterologous challenge with the bacterial pathogen Legionella pneumophila. In contrast, antigen-independent re-activation of CD4+ memory TIA cells accelerates disease onset in an autoimmune model of multiple sclerosis. Our findings demonstrate that memory Th1 cells can acquire additional TCR-independent functionality to mount rapid, innate-like responses that modulate susceptibility to heterologous challenges.

immunology↗

bioRxiv2022

Microbiota colonization tunes the antigen threshold of microbiota-specific T cell activation in the gut

Harnessing the potential of commensal bacteria for immunomodulatory therapy in the gut requires the identification of conditions that modulate immune activation towards incoming colonizing bacteria. In this study, we used the commensal Bacteroides thetaiotaomicron (B.theta) and combined it with B.theta-specific transgenic T cells, in the context of defined colonization of gnotobiotic and immunodeficiency mouse models, to probe the factors modulating bacteria-specific T cell activation against newly colonizing bacteria. After colonizing germ-free (GF) and conventionally raised (SPF) mice with B.theta, we only observed proliferation of B.theta-specific T cells in GF mice. Using simple gnotobiotic communities we could further demonstrate that T-cell activation against newly colonizing gut bacteria is restricted by previous bacteria colonization in GF mice. However, this restriction requires a functional adaptive immune system as Rag1-/- allowed B.theta-specific T cell proliferation even after previous colonization. Interestingly, this phenomenon seems to be dependent on the type of TCR-transgenic model used. B.theta-specific transgenic T cells also proliferated after gut colonization with an E.coli strain carrying the B.theta-specific epitope. However, this was not the case for the SM-1 transgenic T cells as they did not proliferate after similar gut colonization with an E.coli strain expressing the cognate epitope. In summary, we found that activation of T cells towards incoming bacteria in the gut is modulated by the influence of colonizing bacteria on the adaptive immune system of the host.

immunology↗

bioRxiv2022

Single-cell immune repertoire sequencing of B and T cells in murine models of infection and autoimmunity

Adaptive immune repertoires are composed by the ensemble of B and T cell receptors (BCR, TCR) within an individual and reflect both past and current immune responses. Recent advances in single-cell sequencing enable recovery of the complete adaptive immune receptor sequences in addition to transcriptional information. Such high-dimensional datasets enable the molecular quantification of clonal selection of B and T cells across a wide variety of conditions such as infection and disease. Due to costs, time required for the analysis and current practices of academic publishing, small-scale sequencing studies are often not made publicly available, despite having informative potential to elucidate immunological principles and guide future-studies. Here, we performed single-cell sequencing of B and T cells to profile clonal selection across murine models of viral infection and autoimmune disease. Specifically, we recovered transcriptome and immune repertoire information for polyclonal T follicular helper cells following acute and chronic viral infection, CD8+ T cells with binding specificity restricted to two distinct peptides of lymphocytic choriomeningitis virus, and B and T cells isolated from the nervous system in the context of experimental autoimmune encephalomyelitis. We could relate repertoire features such as clonal expansion, germline gene usage, and clonal convergence to cell phenotypes spanning activation, memory, naive, antibody secretion, T cell inflation, and regulation. Together, this dataset provides a resource for experimental and computational immunologists that can be integrated with future single-cell immune repertoire and transcriptome sequencing datasets.

immunology↗