BackgroundCurrent immunotherapies still have limited successful rates among cancers. It is now recognized that T cell functional state in the tumor microenvironment (TME) is a key determinant for effective antitumor immunity and immunotherapy. In addition to exhaustion, cellular senescence in tumor-infiltrating T cells (TILs) has recently been identified as an important T cell dysfunctional state induced by various malignant tumors. Therefore, a better understanding of the molecular mechanism responsible for T cell senescence in the TME and development of novel strategies to prevent effector T cell senescence are urgently needed for cancer immunotherapy.MethodsSenescent T cell populations in the TMEs in mouse lung cancer, breast cancer, and melanoma tumor models were evaluated. Furthermore, T cell senescence induced by mouse tumor and regulatory T (Treg) cells in vitro was determined with multiple markers and assays, including real-time PCR, flow cytometry, and histochemistry staining. Loss-of-function strategies with pharmacological inhibitors and the knockout mouse model were used to identify the potential molecules and pathways involved in T cell senescence. In addition, melanoma mouse tumor immunotherapy models were performed to explore the synergistical efficacy of antitumor immunity via prevention of tumor-specific T cell senescence combined with anti-programmed death-ligand 1 (anti-PD-L1) checkpoint blockade therapy.ResultsWe report that both mouse malignant tumor cells and Treg cells can induce responder T cell senescence, similar as shown in human Treg and tumor cells. Accumulated senescent T cells also exist in the TME in tumor models of lung cancer, breast cancer and melanoma. Induction of ataxia-telangiectasia mutated protein (ATM)-associated DNA damage is the cause for T cell senescence induced by both mouse tumor cells and Treg cells, which is also regulated by mitogen-activated protein kinase (MAPK) signaling. Furthermore, blockages of ATM-associated DNA damage and/or MAPK signaling pathways in T cells can prevent T cell senescence mediated by tumor cells and Treg cells in vitro and enhance antitumor immunity and immunotherapy in vivo in adoptive transfer T cell therapy melanoma models. Importantly, prevention of tumor-specific T cell senescence via ATM and/or MAPK signaling inhibition combined with anti-PD-L1 checkpoint blockade can synergistically enhance antitumor immunity and immunotherapy in vivo.ConclusionsThese studies prove the novel concept that targeting both effector T cell senescence and exhaustion is an effective strategy and can synergistically enhance cancer immunotherapy.
Hepatic glucose production (HGP) is fine-regulated via glycogenolysis or gluconeogenesis to maintain physiological concentration of blood glucose during fasting-feeding cycle. Aberrant HGP leads to hyperglycemia in obesity-associated diabetes. Adipose tissue cooperates with the liver to regulate glycolipid metabolism. During these processes, adipose tissue macrophages (ATMs) change their profiles with various physio-pathological settings, producing diverse effects on HGP. Here, we briefly review the distinct phenotypes of ATMs under different nutrition states including feeding, fasting or overnutrition, and detail their effects on HGP. We discuss several pathways by which ATMs regulate hepatic gluconeogenesis or glycogenolysis, leading to favorable or unfavorable metabolic consequences. Furthermore, we summarize emerging therapeutic targets to correct metabolic disorders in morbid obesity or diabetes based on ATM-HGP axis. This review puts forward the importance and flexibility of ATMs in regulating HGP, proposing ATM-based HGP modulation as a potential therapeutic approach for obesity-associated metabolic dysfunction.
Immunotherapy is the most promising treatment for hepatocellular carcinoma (HCC). However, the immunosuppressive microenvironment and necrosis limit its therapeutic effectiveness. Carbon nanotubes (CNTs) have good tissue permeability and can penetrate tumor necrosis area. Here we constructed a Durvalumab/CNT/PEI/ aptamer-siRNA chimera (chimera/Durmab/CNT) nanoparticles for the immunotherapy of HCC. In vivo and in vitro experiments showed that aptamer-siRNA chimeras could specifically bind HCC cells and inhibit the triggering receptor expressed on myeloid cells-2 (Trem2) expression, but had no effect on Trem2 expression in normal liver and lung. Transmission electron microscope (TEM) results showed that the CNT/PEI nanoparticles were 20-30 nm in diameter and 200-350nm in length. Dense PEI attachment can be observed on CNTs. CNT/PEI nanoparticles could control the sustained release of Durvalumab for 48 hours. In vitro experimental results showed that chimera/Durmab/CNT could increase the proportion of T cells and CD8+T cells, and then promote the apoptosis of HepG2 cells, and the therapeutic effect was superior to aptamer/Durmab/CNT and Durmab/CNT. We constructed a tumor-bearing mouse model, and the results showed that chimera/Durmab/CNT significantly inhibited the growth of transplanted tumor, and the volume and proliferation was further reduced in the chimera/Durmab/CNT group compared with the aptamer/Durmab/CNT group. T cells and CD8+T cells infiltration, and HCC cell apoptosis were significantly increased in the chimera/Durmab/CNT group. In conclusion, we constructed a Durvalumab/CNT/PEI/chimera, which can effectively treat HCC by activating anti-tumor immunity.
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