Molecular, metabolic, and functional CD4 T cell paralysis in the lymph node impedes tumor control

Lymph node macrophages drive immune tolerance and resistance to cancer therapy by induction of the immune-regulatory cytokine IL-33

Apoptotic cells are immunosuppressive, creating a barrier in cancer treatment. Thus, we investigated immune responses to dying tumor cells after therapy in the tumor draining lymph node (TDLN). A key population responsible for clearing tumor material in the TDLN was medullary sinus macrophages (MSMs). Tumor debris phagocytosis by MSMs induces the cytokine IL-33, and blocking the IL-33 receptor (ST2) or deletion of Il33 in MSMs enhances therapy responses. Mechanistically, IL-33 activates T regulatory cells in TDLNs that migrate to the tumor to suppress CD8+ T cells. Therapeutically combining ST2 blockade, targeted kinase inhibitors, and anti-PD-1 immunotherapy increases CD8+ T cell activity promoting tumor regression. Importantly, we observe similar activity in human macrophages, and IL-33 expression in sentinel lymph nodes correlates with disease stage and survival in melanoma. Thus, our data identifies an IL-33-dependent immune response to therapy that attenuates therapy-induced anti-tumor immunity.

Vitamin D Decreases Susceptibility of CD4+ T Cells to HIV Infection by Reducing AKT Phosphorylation and Glucose Uptake: A Bioinformatic and In Vitro Approach

Activated immune cells are highly susceptible to human immunodeficiency virus (HIV) infection. Vitamin D (VitD) induces antimicrobial responses and reduces cellular activation. We investigated VitD effects on HIV-1 replication, glucose uptake, and gene regulation using computational and in vitro approaches. CD4+ T cells from healthy male donors were treated with VitD and infected with HIV-1. After 72 h, p24 protein was measured to assess viral replication. VitD effects on anti- and pro-HIV genes were analyzed by a Boolean network model based on curated databases and the literature. CCR5 and CXCR4 coreceptor expression, AKT phosphorylation, and glucose uptake were evaluated by flow cytometry, and expression of some model-identified genes was quantified by qPCR. VitD reduced p24 by 53.2% (p = 0.0078). Boolean network modeling predicted that VitD upregulates antiviral, migration, and cell-differentiation related genes, while downregulating genes related to cellular activation, proliferation, glucose metabolism, and HIV replication, notably AKT1, CCNT1, SLC2A1, HIF1A, and PFKL. In vitro, VitD reduced AKT phosphorylation by 26.6% (p = 0.0156), transcription of CCNT1 by 22.7% (p = 0.0391), and glucose uptake by 22.8% (p = 0.0039) without affecting classic antiviral genes or coreceptor expression. These findings suggest an anti-HIV effect of VitD, mediated through AKT and glucose metabolism downmodulation, both involved in cell activation and HIV-1 replication.

CD4 T cell dysfunction is associated with bacterial recrudescence during chronic tuberculosis

While most people contain Mycobacterium tuberculosis infection, some individuals develop active disease, usually within two years of infection. Why immunity fails after initially controlling infection is unknown. C57BL/6 mice control Mycobacterium tuberculosis for up to a year but ultimately succumb to disease. We hypothesize that the development of CD4 T cell dysfunction permits bacterial recrudescence. We developed a reductionist model to assess antigen-specific T cells during chronic infection and found evidence of CD4 T cell senescence and exhaustion. In C57BL/6 mice, CD4 T cells upregulate coinhibitory receptors and lose effector cytokine production. Single cell RNAseq shows that only a small number of CD4 T cells in the lungs of chronically infected mice are polyfunctional. While the origin and causal relationship between T-cell dysfunction and recrudescence remains uncertain, we propose T cell dysfunction leads to a feed-forward loop that causes increased bacillary numbers, greater T cell dysfunction, and progressive disease.

CD4 T cell dysfunction is associated with bacterial recrudescence during chronic tuberculosis

While most people contain Mycobacterium tuberculosis infection, some individuals develop active disease, usually within two years of infection. Why immunity fails after initially controlling infection is unknown. C57BL/6 mice control Mycobacterium tuberculosis for up to a year but ultimately succumb to disease. We hypothesize that the development of CD4 T cell dysfunction permits bacterial recrudescence. We developed a reductionist model to assess antigen-specific T cells during chronic infection and found evidence of CD4 T cell senescence and exhaustion. In C57BL/6 mice, CD4 T cells upregulate coinhibitory receptors and lose effector cytokine production. Single cell RNAseq shows that only a small number of CD4 T cells in the lungs of chronically infected mice are polyfunctional. While the origin and causal relationship between T-cell dysfunction and recrudescence remains uncertain, we propose T cell dysfunction leads to a feed-forward loop that causes increased bacillary numbers, greater T cell dysfunction, and progressive disease.

Astragaloside IV augments anti-PD-1 therapy to suppress tumor growth in lung cancer by remodeling the tumor microenvironment

Programmed cell death protein-1 (PD-1) inhibitors are increasingly utilized in the treatment of lung cancer (LC). Combination therapy has recently gained popularity in treating LC. This study aimed to assess the efficacy of combining Astragaloside IV (AS-IV) and anti-PD-1 in LC. C57BL/6J mice were subcutaneously injected with Lewis lung carcinoma (LLC) cells. After 3 weeks, the animals were sacrificed, and the tumors were harvested for analysis. Ki-67 immuno-labeling and TUNEL assay were used for evaluating cell proliferation and apoptosis in tumor tissues. In addition, anti-cleaved caspase 3 was used for immunolabelling of apoptotic cells. Immune cell infiltration (macrophages and T cells) and gene expression in tumor tissues were also investigated by using immunofluorescence staining. Compared to treatment with anti-PD-1 or AS-IV, the combination of AS-IV and anti-PD-1 notably reduced tumor volume and weight of LLC-bearing mice. Additionally, the combination treatment strongly induced the apoptosis and suppressed the proliferation in tumor tissues through inactivating PI3K/Akt and ERK signaling pathways, compared to single treatment group. Moreover, the combination treatment elevated levels of the M1 macrophage marker mCD86, reduced levels of the M2 macrophage marker mCD206, as well as upregulated levels of the T cell activation marker mCD69 in tumor tissues. Collectively, the combination treatment effectively inhibited tumor growth in LLC mice through promoting M1 macrophage polarization and T cell activation. These findings showed that combining AS-IV with anti-PD-1 therapy could be a promising therapeutic approach for LC.

Regulation and impact of tumor-specific CD4+ T cells in cancer and immunotherapy

CD4+ T cells are crucial in generating and sustaining immune responses. They orchestrate and fine-tune mammalian innate and adaptive immunity through cell-based interactions and the release of cytokines. The role of these cells in contributing to the efficacy of antitumor immunity and immunotherapy has just started to be uncovered. Yet, many aspects of the CD4+ T cell response are still unclear, including the differentiation pathways controlling such cells during cancer progression, the external signals that program them, and how the combination of these factors direct ensuing immune responses or immune-restorative therapies. In this review, we focus on recent advances in understanding CD4+ T cell regulation during cancer progression and the importance of CD4+ T cells in immunotherapies.

Therapeutic Targeting of Glioblastoma and the Interactions with Its Microenvironment

Glioblastoma (GBM) is the most common primary malignant brain tumour, and it confers a dismal prognosis despite intensive multimodal treatments. Whilst historically, research has focussed on the evolution of GBM tumour cells themselves, there is growing recognition of the importance of studying the tumour microenvironment (TME). Improved characterisation of the interaction between GBM cells and the TME has led to a better understanding of therapeutic resistance and the identification of potential targets to block these escape mechanisms. This review describes the network of cells within the TME and proposes treatment strategies for simultaneously targeting GBM cells, the surrounding immune cells, and the crosstalk between them.