Biology subjects

Thaxton, J. E.

Publications and source records attributed to Thaxton, J. E..

9 recordsLinked to original sources

bioRxiv2026

Folate metabolism in tumor-associated macrophages drives immunosuppressive function to promote tumor growth

Tumor-associated macrophages (TAMs) promote tumor growth, inhibit effector lymphocytes, and induce resistance to immune checkpoint inhibitors (ICI). Therapies designed to deplete TAMs have had little success in the clinic, and strategies aimed to repolarize immunosuppressive TAMs to pro-inflammatory states have struggled with systemic toxicity. We have identified that the combination of low folate in the tumor microenvironment and TAM dependency on the high affinity folate receptor beta (FR{beta}) for folate uptake results in a unique metabolic dependency of TAMs necessary for their immunosuppressive function. FR{beta} (encoded by Folr2) is uniquely expressed on myeloid cells and upregulated on TAMs. FR{beta}+ TAMs exhibit an immunosuppressive phenotype in melanoma and are associated with worse clinical outcomes and resistance to ICI in melanoma patients. We generated a novel Folr2-/- mouse model to study why TAMs express a unique folate receptor and showed that tumor growth was slowed in the absence of Folr2 in a T-cell dependent manner. We observed a dramatic repolarization of Folr2-/- TAMs in vivo to pro-inflammatory states, resulting in increased cytotoxic T cell and NK cell infiltration into tumors. Importantly, we show that folate is low in the tumor microenvironment by performing metabolomics on melanoma tumors and adjacent normal tissue from warm autopsy patient specimens, and that we could increase tumor growth in Folr2-/- mice by increasing serum folate to supraphysiologic concentrations with a high folate diet. Integrated metabolomics and transcriptomic analysis demonstrated that Folr2-/- macrophages have impaired folate uptake and 1C metabolism-based reduction of oxidized glutathione in low folate conditions, resulting in increased mitochondrial reactive oxygen species (ROS) in Folr2-/- cells. Excess ROS results in leakage of mitochondrial DNA into the cytoplasm, activating cGAS-STING signaling and promoting pro-inflammatory macrophage polarization through TBK1 and NF-kB. Together, our data demonstrate that TAM expression of FR{beta} promotes their immunosuppressive functions by maintaining folate uptake in the low folate tumor microenvironment, suggesting that FR{beta} is a novel metabolic checkpoint on TAMs.

immunology↗

bioRxiv2026

Metabolically Activated Proteostasis Regulators Reduce Differentiation of CD4+ TH17 Cells

The differentiation of naive CD4+ T cells into effector T cell subsets such as TH1, TH2, TH17 and TREG cells is governed by tightly coordinated activation programmes dependent on T cell receptor (TCR) engagement, co-stimulation, and cytokine signalling. This differentiation process involves regulation of stress-responsive signalling pathways such as the unfolded protein response (UPR) and the oxidative stress response (OSR) to adapt to the physiologic demands specific to distinct T cell subset functions. This suggests that pharmacologically targeting stress-responsive pathways offers a unique opportunity to selectively remodel the differentiation of these different T cell subsets. We previously identified compound AA147 as a metabolically activated proteostasis regulator that can induce both the ATF6 signalling arm of the UPR and, in certain cell types, the NRF2-regulated arm of the OSR. (Paxman et al., 2018; Plate et al., 2016) Here, we show that treatment with AA147 selectively reduces differentiation of pro-inflammatory TH17 cells by promoting degradation of the lineage-specifying transcription factor RORgammat, without impacting the transcription factors of other CD4+ T cell subsets. AA147-dependent reduction in TH17 differentiation is independent of ATF6 activation and involves activation of NRF2, which reduces intracellular reactive oxygen species (ROS) to hinder TH17 cell differentiation. Apart from RORgammat, we found that AA147 decreases expression of the TCR-responsive factor IRF4, thus suppressing production of select effector cytokines across effector T cells, demonstrating additional ways in which this compound reshapes the activities of these essential T cell subsets. Our results demonstrate the potential for metabolically activated proteostasis regulators such as AA147 to selectively reshape TH17 cell identity while broadly dampening effector cytokine responses across effector T cell subsets, through both NRF2-dependent and independent mechanisms during T cell differentiation.

cell biology↗

bioRxiv2026

Fatty Acid Oxidation Suppression Reprograms Fibroblasts in Fibrostenotic Crohns Disease

Fibrostenotic complications represent a major cause of morbidity in Crohns disease (CD), yet the cellular mechanisms that drive intestinal fibrosis independent of active inflammation remain poorly understood. Here, we identify impaired fatty acid oxidation (FAO) as a defining metabolic feature of fibroblasts in fibrostenotic CD. Untargeted lipidomics of non-inflamed colonic tissue from CD patients demonstrated enrichment of triacylglycerols and long-chain acylcarnitines, suggesting altered lipid utilization. Across three independent RNA-sequencing cohorts, including treatment-naive pediatric ileal biopsies, FAO genes (CPT1A, CPT2, SLC25A20) were selectively downregulated in patients with or destined to develop fibrostenotic disease. Single-cell RNA-sequencing localized these transcriptional alterations specifically to fibroblasts within strictured ileum. Primary fibroblasts derived from fibrostenotic CD exhibited increased neutral lipid accumulation, impaired mitochondrial fatty acid trafficking, and diminished responsiveness to PPAR{gamma}-mediated suppression of TGF{beta}-induced myofibroblast activation. Together, these findings demonstrate that FAO impairment is a conserved, fibroblast-specific metabolic program associated with intestinal fibrosis in CD and suggest that metabolic modulation of stromal cells represents a potential therapeutic strategy for fibrostenotic disease.

genomics↗

bioRxiv2026

Latent Regulatory Programs Generate Synthetic T Cell States with Enhanced Therapeutic Potential

Transcription factors (TFs) govern cell fate through coordinated gene-regulatory networks, yet the full potential of these networks to generate non-native, therapeutically advantageous cell states in vivo remains largely unexplored. We hypothesized that systematic gain-of-function (GOF) overexpression of TFs in CD8 T cells, central mediators of immune protection, could reveal latent, or "hidden," regulatory programs capable of generating synthetic T cell states with therapeutic utility. To test this, we developed single-cell GOF sequencing (scGOF-seq), a multiplexed platform for unbiased, in vivo mapping of GOF effects on T cell fate in immunocompetent mouse models of infection and cancer. scGOF-seq uncovered unexpected regulators of T cell differentiation and accumulation, including SOX2, OCT4, and GATA2, which are normally silenced during T cell differentiation. Notably, outside its native regulatory context, supraphysiologic cMyc GOF reprogrammed CD8 T cells into a synthetic stem-effector hybrid state, enabling >5,000-fold antigen-dependent expansion and antitumor activity, contrasting sharply with its native function in driving terminal differentiation. scGOF-seq further identified TF modules that cooperate with cMyc GOF to promote robust CD8 T cell responses in solid tumors. Together, these findings establish GOF perturbation as a powerful strategy for revealing latent immune regulatory programs and engineering synthetic immune states with therapeutic potential. One-Sentence SummaryIn vivo single-cell gain-of-function screening reveals latent transcriptional programs that can reprogram T cells into highly functional synthetic states.

immunology↗

bioRxiv2023

Adaptive IRE1 Signaling Elicits T Cell Metabolic Remodeling and Tumor Control

The efficacy of cancer immunotherapies is limited by the metabolic instability of the tumor microenvironment (TME) that disables T cell antitumor immunity. Metabolic imbalances within the TME are sensed and responded to by stress sensors of the endoplasmic reticulum (ER) unfolded protein response (UPR). The UPR comprises three integrated signaling pathways harboring both adaptive and deleterious phases based on the extent and duration of cell stress. Here, we elucidate the differential contributions of adaptive and deleterious signaling downstream of the UPR IRE1 pathway in T cell-regulated tumor control. T cells in murine and patient cancers experience persistent ER stress, leading to hyperactive IRE1 signaling that limits tumor control. However, amplifying the adaptive arm of the IRE1 UPR serves to eliminate mitochondrial toxicity and protect T cells from chronic ER stress, yielding robust tumor engraftment and long-term tumor immunity. Our findings establish the UPRs essential protective role in antitumor immunity.

immunology↗

bioRxiv2023

Acetyl-CoA Carboxylase Obstructs CD8+ T-Cell Lipid Utilization and Energy Synthesis in the Tumor Microenvironment

The solid tumor microenvironment (TME) imprints a compromised metabolic state in tumor infiltrating T cells (TILs) hallmarked by the inability to maintain effective energy synthesis for antitumor function and survival. T cells in the TME must catabolize lipids via mitochondrial fatty acid oxidation (FAO) to supply energy in nutrient stress, and it is established that T cells enriched in FAO are adept at cancer control. However, endogenous TILs and unmodified cellular therapy products fail to sustain bioenergetics in tumors. Using patient samples and mouse models, we reveal that the solid TME imposes perpetual acetyl-CoA carboxylase (ACC) activity, enforcing lipid biogenesis and storage in TILs that directly opposes FAO. Using metabolic, lipidomic, and confocal imaging strategies, we find that restricting ACC wholly rewires T cell metabolism, enabling energy maintenance in TME stress. Moreover, limiting ACC activity potentiates a gene and phenotypic program indicative of T cell memory, engendering TILs with increased survival and polyfunctionality, with the ability to control solid cancer.

immunology↗

bioRxiv2023

The degree of T cell stemness differentially impacts the potency of adoptive cancer immunotherapy in a Lef-1 and Tcf-1 dependent manner.

Generating stem memory T cells (TSCM) is a key goal for improving cancer immunotherapy. Yet, the optimal way to modulate signaling pathways that enrich TSCM properties remains elusive. Here, we discovered that the degree to which the PI3K{delta} pathway is blocked pharmaceutically can generate T cells with differential levels of stemness properties. This observation was based on the progressive enrichment of transcriptional factors of stemness (Tcf-1 and Lef-1). Additional investigation revealed that T cells with high stemness features had enhanced metabolic plasticity, marked by heightened mitochondrial function and glucose uptake. Conversely, T cells with low or medium features of stemness expressed more inhibitory checkpoint receptors (Tim-3, CD39) and were vulnerable to antigen-induced cell death. Only TCR-antigen specific T cells with high stemness persisted following adoptive transfer in vivo and mounted protective immunity to melanoma tumors. Likewise, the strongest level of PI3K{delta} blockade in vitro generated human tumor infiltrating lymphocytes (TILs) and CAR T cells with heightened stemness properties, in turn bolstering their capacity to regress human mesothelioma tumors. We find that the level of stemness T cells possess in vitro differentially impacts their potency upon transfer in three tumor models. Mechanistically, both Lef-1 and Tcf-1 sustain anti-tumor protection by high TSCM, as deletion of either one compromised cellular therapy. Collectively, these findings highlight the therapeutic potential of carefully modulating PI3K{delta} signaling in T cells to confer high stemness and mediate protective responses to solid tumors.

immunology↗

bioRxiv2022

Stress-Mediated Attenuation of Translation Undermines T Cell Tumor Control

Protein synthesis enables cell growth and survival, but the molecular mechanisms through which T cells suppress or maintain protein translation in the stress of solid tumors are unknown. Using mouse models and human tumors we demonstrate that protein translation in T cells is repressed by the solid tumor microenvironment (TME) due to activation of the unfolded protein response (UPR) via phosphorylation of the subunit of eukaryotic translation initiation factor 2 (p-eIF2). Given that acute glucose deprivation in T cells exacerbated p-eIF2, we show that metabolic reprogramming toward glycolytic independence allays the UPR and p-eIF2, enabling sustained protein translation in T cells in TME stress. UPR mitigation was associated with enhanced degradation of proteins in antitumor T cells, as proteasome inhibition resulted in eIF2 phosphorylation, attenuation of translation, and loss of antitumor efficacy. In contrast, proteasome stimulation relieved translation inhibition, inducing robust T cell tumor control, offering a new therapeutic avenue to fuel the efficacy of tumor immunotherapy.

immunology↗

bioRxiv2021

B cells imprint adoptively transferred CD8+ T cells with enhanced tumor immunity

Here we report a novel strategy to reverse the tolerant state of adoptively transferred CD8+ T cells against melanoma through ex vivo expansion with the TLR9 agonist CpG. T cells generated in the presence of CpG display potent anti-tumor efficacy without in vivo co-administration of high dose IL-2 or vaccination, which are classically required for effective treatment of solid tumors using adoptive cell therapies. CD8+ T cells adopt a unique proteomic signature and are characterized by an IL-2RhighICOShighCD39low phenotype after CpG-mediated expansion. Surprisingly, we found that the presence of B cells, in the culture, was essential for imprinting CD8+ T cells with this phenotype and moreover purified B cells were sufficient to mediate the CpG-associated changes in T cells. These findings reveal a vital role for B cells in the generation of effective antitumor CD8+ T cells and have immediate implications for profoundly improving immunotherapy for patients. SUMMARY STATEMENTThe TLR9 agonist CpG allows B cells to license adoptively transferred CD8+ T cells with potent tumor immunity. These licensed T cells have a unique proteomic signature, are marked by low CD39 and high ICOS and IL-2R expression, and engraft robustly in vivo.

immunology↗