Biology subjects

Gileadi, U.

Publications and source records attributed to Gileadi, U..

6 recordsLinked to original sources

bioRxiv2025

Mitochondrial genetics defines anti-tumour immunity through mitochondrial ROS and PD-1 signalling

As central players in cell metabolism, mitochondria influence numerous aspects of health and disease, including the initiation and progression of cancer. Although mitochondrial DNA (mtDNA) mutations have been extensively documented in human cancers for decades, the functional impact of mitochondrial haplogroups on tumour biology remains largely unexplored. Here, we investigate the role of mitochondrial variability in tumour biology using conplastic mouse strains, which are animal models with identical nuclear genomes but different mtDNA haplotypes. We showed that the physiologically relevant variation in mitochondrial ROS (mROS) generation, associated with specific clusters of mtDNA single nucleotide polymorphisms (SNPs), modulated immune responses within the tumour microenvironment and altered tumour growth. We observed strain-dependent differences in the abundance of multiple immune subsets and in PD-1 expression in tumour-infiltrating lymphocytes (TILs). In addition, mtDNA haplotypes influenced cancer progression by modulating tumour angiogenesis through an mROS-independent mechanism. These findings connect nucleo-mitochondrial genetic variability to tumour progression, de novo vessel formation and anti-tumour immunity. Tumour immunotherapies should incorporate the spatial and temporal dynamics of cancer evolution and consider mitochondrial genetics as a targetable layer influencing treatment efficacy.

cancer biology↗

bioRxiv2024

IFNgamma-dependent remodelling of the myeloid landscape underlies control of IFNgamma-insensitive tumours

Loss of IFN{gamma}-sensitivity by tumours is thought to be a mechanism enabling evasion, as some cancers lacking IFN{gamma}-signalling demonstrate resistance to checkpoint immunotherapy. However, recent studies demonstrated that IFN{gamma}-resistant tumours are well-controlled and sensitized for immunotherapy. The underlying mechanism leading to enhanced immune responses in those patients is unknown. Using IFN{gamma}-insensitive melanoma tumours which were well-controlled by the endogenous anti-tumour response, we found that despite low basal MHC class I expression by tumours, CD8+ T cell infiltration was not hindered and, unexpectedly, their production of IFN{gamma} was still important for tumour control. Mechanistically, IFN{gamma} triggers pro-inflammatory remodelling of IFN{gamma}-insensitive tumours, affecting the differentiation of myeloid cells. Predominantly, immunosuppressive macrophages are inhibited, while inflammatory phenotypes of monocytes and mono-macs are preserved in IFN{gamma}-insensitive tumours. This is supported by a co-dependency between CD8+ T cells and monocyte/macrophages, as depletion of one resulted in loss of the other. Our work demonstrates an important mechanistic understanding of how IFN{gamma} resistance does not preclude failure of anti-tumour responses. Importantly, immune remodelling appears to be dominant in IFN{gamma}-sensitive and IFN{gamma}-insensitive mixed tumours, and is enriched in humans with tumours mutated in the IFN{gamma} pathway, suggesting this may be leveraged for therapy in the future.

immunology↗

bioRxiv2022

Immunofilaments Provide a Nanoscale Platform for In Vivo T Cell Expansion and Cancer Immunotherapy

Adoptive T cell therapy has successfully been implemented for the treatment of cancer. Nevertheless, the precarious ex vivo expansion of T cells by artificial antigen-presenting cells (aAPCs) remains cumbersome and can compromise T cell functionality, thereby limiting their therapeutic potential. Here, we propose a radically different approach aiming at direct expansion of T cells in vivo, thereby omitting the need for large-scale ex vivo T cell production. We engineered nanosized immunofilaments (IFs), consisting of a soluble semiflexible polyisocyanopeptide polymer backbone that presents peptide-loaded major histocompatibility complexes and co-stimulatory molecules in a multivalent fashion. We demonstrate that IFs readily activate and expand antigen-specific T cells in a manner highly similar to natural APCs, as evidenced by transcriptomic analyses of T cells. Upon intravenous injection, IFs reach lymphoid organs including spleen and lymph nodes and induce antigen-specific T cell responses in vivo. Moreover, IFs display remarkable anti-tumor efficacy resulting in inhibition of melanoma metastases formation and reduction of primary tumor growth in synergy with immune checkpoint blockade. In conclusion, nanosized IFs represent a powerful new type of aAPC that provide a modular platform for direct activation and expansion of antigen-specific T cells in vivo, which can greatly contribute to cancer immunotherapy.

immunology↗

bioRxiv2019

Semaphorin 3A induces cytoskeletal paralysis in tumor-specific CD8+ T cells

Semaphorin-3A (Sema3A) regulates tumor angiogenesis, but its role in modulating anti-tumor immunity is unclear. We demonstrate that Sema3A secreted within the tumor microenvironment (TME) suppresses tumor-specific CD8+ T cell function via Neuropilin-1 (NRP1), a receptor that is upregulated upon activation with T cells cognate antigen. Sema3A inhibits T cell migration, assembly of the immunological synapse, and tumor killing. It achieves these functional effects through hyper-activating the acto-myosin system in T cells leading to cellular paralysis. Finally, using a clear cell renal cell carcinoma patient cohort, we demonstrate that human tumor-specific CD8+ T cells express NRP1 and are trapped in Sema3A rich regions of tumors. Our study establishes Sema3A as a potent inhibitor of anti-tumor immunity.

immunology↗

bioRxiv2019

NOD2 and TLR2 Signal via TBK1 and PI31 to Direct Cross-presentation and CD8 T Cell Responses

NOD2 and TLR2 recognize components of bacterial cell wall peptidoglycan and direct defense against enteric pathogens. CD8+ T cells are important for immunity to such pathogens but how NOD2 and TLR2 induce antigen specific CD8+ T cell responses is unknown. Here, we define how these pattern recognition receptors (PRRs) signal in primary dendritic cells (DCs) to influence MHC class I antigen presentation. We show NOD2 and TLR2 phosphorylate PI31 via TBK1 following activation in DCs. PI31 interacts with TBK1 and Sec16A at endoplasmic reticulum exit sites (ERES), which positively regulates MHC class I peptide loading and immunoproteasome stability. Following NOD2 and TLR2 stimulation, depletion of PI31 or inhibition of TBK1 activity in vivo impairs DC cross-presentation and CD8+ T cell activation. DCs from Crohns patients expressing NOD2 polymorphisms show dysregulated cross-presentation and CD8+ T cell responses. Our findings reveal unidentified mechanisms that underlie CD8+ T cell responses to bacteria in health and in Crohns.

immunology↗

bioRxiv2018

Precise tuning of gene expression output levels in mammalian cells

Precise, analogue regulation of gene expression is critical for development, homeostasis and regeneration in mammals. In contrast, widely employed experimental and therapeutic approaches such as knock-in/out strategies are more suitable for binary control of gene activity, while RNA interference (RNAi) can lead to pervasive off-target effects and unpredictable levels of repression. Here we report on a method for the precise control of gene expression levels in mammalian cells based on engineered, synthetic microRNA response elements (MREs). To develop this system, we established a high-throughput sequencing approach for measuring the efficacy of thousands of miR-17 MRE variants. This allowed us to create a library of microRNA silencing-mediated fine-tuners (miSFITs) of varying strength that can be employed to control the expression of user specified genes. To demonstrate the value of this technology, we used a panel of miSFITs to tune the expression of a peptide antigen in a mouse melanoma model. This analysis revealed that antigen expression level is a key determinant of the anti-tumour immune response in vitro and in vivo. miSFITs are a powerful tool for modulating gene expression output levels with applications in research and cellular engineering.

synthetic biology↗