A2aR on lung adenocarcinoma cells: A novel target for cancer therapy via recruiting and regulating tumor-associated macrophages

Toxoplasma gondii ROP18 induces maternal-fetal dysfunction by downregulating CD73 expression on decidual macrophages

BACKGROUND

Decidual macrophages (dMφ) are pivotal in maintaining maternal-fetal immune tolerance during normal pregnancy by expressing a range of immune-suppressive molecules, including CD73. It has been demonstrated that Toxoplasma gondii (T. gondii) infection during pregnancy can impair dMφ function, potentially leading to adverse pregnancy outcomes, through downregulation of these inhibitory molecules. T. gondii rhoptry protein 18 (TgROP18), a key virulence factor of T. gondii, is associated with the incapacitation of the host's innate and adaptive immune responses to protect the parasite from elimination. However, the role of TgROP18 in modulating CD73 expression on dMφ and the underlying mechanisms remain to be elucidated.

METHODS

Wild-type (WT) and CD73-deficient (CD73-/-) pregnant mice were subjected to intraperitoneal injection of T. gondii RH or RH-Δrop18 on gestational day (Gd) 8, and subsequently euthanized on Gd 14. Pregnancy outcomes were then evaluated, and the expression levels of CD73, arginase 1 (Arg-1), and interleukin 10 (IL-10) were quantified by flow cytometry. Mononuclear cells isolated from the human aborted decidual tissues were also infected with T. gondii RH or RH-Δrop18 for the analysis of CD73 expression with flow cytometry. Additionally, infected human dMφ were used to assess the expression levels of CD73, Arg-1, IL-10, and their associated signaling molecules by western blot analysis. Furthermore, chromatin immunoprecipitation (ChIP) assays were performed to validate the involved signaling pathways.

RESULTS

Compared with the T. gondii RH-infected group, milder adverse pregnancy outcomes and attenuated expression levels of CD73 on dMφ were observed in T. gondii RH-Δrop18-infected pregnant mice and human decidual tissues. Lysine-specific histone demethylase1 (LSD1) and snail family transcriptional repressor 1 (SNAIL1) were found to be involved in the downregulation of CD73 expression on dMφ following T. gondii infection. Subsequently, reduced expression of CD73 contribute to the downregulation of Arg-1 and IL-10 expression through adenosine A2a receptor (A2AR) / protein kinase A (PKA) / phosphorylated cAMP-response element binding protein (p-CREB) / CCAAT enhancer binding protein B (C/EBPβ) pathway.

CONCLUSIONS

TgROP18 can significantly reduce CD73 expression on dMφ through LSD1/SNAIL1 pathway, subsequently leading to the decreased expression levels of Arg-1 and IL-10 via adenosine/A2AR/PKA/p-CREB/C/EBPβ pathway, which ultimately contributes to maternal-fetal tolerance dysfunction of dMφ.

Metabolic Reprogramming of Immune Cells in the Tumor Microenvironment

Metabolic reprogramming of immune cells within the tumor microenvironment (TME) plays a pivotal role in shaping tumor progression and responses to therapy. The intricate interplay between tumor cells and immune cells within this ecosystem influences their metabolic landscapes, thereby modulating the immune evasion tactics employed by tumors and the efficacy of immunotherapeutic interventions. This review delves into the metabolic reprogramming that occurs in tumor cells and a spectrum of immune cells, including T cells, macrophages, dendritic cells, and myeloid-derived suppressor cells (MDSCs), within the TME. The metabolic shifts in these cell types span alterations in glucose, lipid, and amino acid metabolism. Such metabolic reconfigurations can profoundly influence immune cell function and the mechanisms by which tumors evade immune surveillance. Gaining a comprehensive understanding of the metabolic reprogramming of immune cells in the TME is essential for devising novel cancer therapeutic strategies. By targeting the metabolic states of immune cells, it is possible to augment their anti-tumor activities, presenting new opportunities for immunotherapeutic approaches. These strategies hold promise for enhancing treatment outcomes and circumventing the emergence of drug resistance.

Determining M2 macrophages content for the anti-tumor effects of metal-organic framework-encapsulated pazopanib nanoparticles in breast cancer

Pazopanib (PAZ), an oral multi-tyrosine kinase inhibitor, demonstrates promising cytostatic activities against various human cancers. However, its clinical utility is limited by substantial side effects and therapeutic resistance. We developed a nanoplatform capable of delivering PAZ for enhanced anti-breast cancer therapy. Nanometer-sized PAZ@Fe-MOF, compared to free PAZ, demonstrated increased anti-tumor therapeutic activities in both syngeneic murine 4T1 and xenograft human MDA-MB-231 breast cancer models. High-throughput single-cell RNA sequencing (scRNAseq) revealed that PAZ@Fe-MOF significantly reduced pro-tumorigenic M2-like macrophage populations at tumor sites and suppressed M2-type signaling pathways, such as ATF6-TGFBR1-SMAD3, as well as chemokines including CCL17, CCL22, and CCL24. PAZ@Fe-MOF reprogramed the inhibitory immune microenvironment and curbed tumorigenicity by blocking the polarization of M2 phenotype macrophages. This platform offers a promising and new strategy for improving the cytotoxicity of PAZ against breast cancers. It provides a method to evaluate the immunological response of tumor cells to PAZ-mediated treatment.

Targeting Macrophage Polarization for Reinstating Homeostasis following Tissue Damage

Tissue regeneration and remodeling involve many complex stages. Macrophages are critical in maintaining micro-environmental homeostasis by regulating inflammation and orchestrating wound healing. They display high plasticity in response to various stimuli, showing a spectrum of functional phenotypes that vary from M1 (pro-inflammatory) to M2 (anti-inflammatory) macrophages. While transient inflammation is an essential trigger for tissue healing following an injury, sustained inflammation (e.g., in foreign body response to implants, diabetes or inflammatory diseases) can hinder tissue healing and cause tissue damage. Modulating macrophage polarization has emerged as an effective strategy for enhancing immune-mediated tissue regeneration and promoting better integration of implantable materials in the host. This article provides an overview of macrophages' functional properties followed by discussing different strategies for modulating macrophage polarization. Advances in the use of synthetic and natural biomaterials to fabricate immune-modulatory materials are highlighted. This reveals that the development and clinical application of more effective immunomodulatory systems targeting macrophage polarization under pathological conditions will be driven by a detailed understanding of the factors that regulate macrophage polarization and biological function in order to optimize existing methods and generate novel strategies to control cell phenotype.

Nanoparticles targeting the adenosine pathway for cancer immunotherapy

Cancer immunotherapy, as an emerging approach to cancer treatment, has tremendous potential for application. Compared to traditional methods such as surgery, chemotherapy, and radiation therapy, it has the ability to restore the patient's immune system, leading to long-term immune memory with less damage to normal tissues. However, immunotherapy has its limitations, including limited therapeutic efficacy, restricted patient populations, and inconsistent treatment responses. Finding effective immunotherapeutic approaches has become a key focus of its clinical application. The adenosine pathway is a recently discovered tumor immune regulatory signaling pathway. It can influence the metabolism and growth of tumor cells by acting through key enzymes in the adenosine pathway, thereby affecting the development of tumors. Therefore, inhibiting the adenosine pathway is an effective cancer immunotherapy. Common adenosine pathway inhibitors include small molecules and antibody proteins, and extensive preclinical trials have demonstrated their effectiveness in inhibiting tumor growth. The short half-life, low bioavailability, and single administration route of adenosine pathway inhibitors limit their clinical application. With the advent of nanotechnology, nano-delivery of adenosine pathway inhibitors has addressed these issues. Compared to traditional drugs, nano-drugs extend the drug's circulation time and improve its distribution within the body. They also offer targeting capabilities and have low toxic side effects, making them very promising for future applications. In this review, we discuss the mechanism of the adenosine pathway in tumor immune suppression, the clinical applications of adenosine pathway inhibitors, and nano-delivery based on adenosine pathway inhibitors. In the final part of this article, we also briefly discuss the technical issues and challenges currently present in nano-delivery of adenosine pathway inhibitors, with the hope of advancing the progress of adenosine inhibitor nano-drugs in clinical treatment.

The Biological Role of Macrophage in Lung and Its Implications in Lung Cancer Immunotherapy

The lungs are the largest surface of the body and the most important organ in the respiratory system, which are constantly exposed to the external environment. Tissue Resident Macrophages in lung constitutes the important defense against external pathogens. Macrophages connects the innate and adaptive immune system, and also plays important roles in carcinogenesis and cancer immunotherapy. Lung cancer is the leading cause of cancer-related death worldwide, with an overall five-year survival rate of only 21%. Macrophages that infiltrate or aggregate in lung tumor microenvironment are defined as tumor-associated macrophages (TAMs). TAMs are the main components of immune cells in the lung tumor microenvironment. The differentiation and maturation process of TAMs can be roughly divided into two different types: classical activation pathway produces M1 tumor-associated macrophages, and bypass activation pathway produces M2 tumor-associated macrophages. Studies have found that TAMs are related to tumor invasion, metastasis, and treatment resistance, and show potential as a new target for tumor immunotherapy. Therefore, the biological function of macrophages in lung and the role of TAMs in the occurrence, development, and treatment of lung cancer are discussed in this paper.

Targeting the adenosine signaling pathway in macrophages for cancer immunotherapy

One of the ways in which macrophages support tumorigenic growth is by producing adenosine, which acts to dampen antitumor immune responses and is generated by both tumor and immune cells in the tumor microenvironment (TME). Two cell surface expressed molecules, CD73 and CD39, boost catalytic adenosine triphosphate, leading to further increased adenosine synthesis, under hypoxic circumstances in the TME. There are four receptors (A1, A2A, A2B, and A3) expressed on macrophages that allow adenosine to perform its immunomodulatory effect. Researchers have shown that adenosine signaling is a key factor in tumor progression and an attractive therapeutic target for treating cancer. Several antagonistic adenosine-targeting biological therapies that decrease the suppressive action of tumor-associated macrophages have been produced and explored to transform this result from basic research into a therapeutic advantage. Here, we'll review the newest findings from studies of pharmacological compounds that target adenosine receptors, and their potential therapeutic value based on blocking the suppressive action of macrophages in tumors.

Integrating bulk-RNA sequencing and single-cell sequencing analyses to characterize adenosine-enriched tumor microenvironment landscape and develop an adenosine-related prognostic signature predicting immunotherapy in lung adenocarcinoma

The adenosine-signaling axis has been recognized as an important immunomodulatory pathway in tumor immunity. However, the biological role of the adenosine-signaling axis in the remodeling of the tumor microenvironment (TME) in lung adenocarcinoma (LUAD) remains unclear. Here, we quantified adenosine signaling (ado_sig) in LUAD samples using the GSVA method and assessed the prognostic value of adenosine in LUAD. Afterward, we explored the heterogeneity of the tumor-immune microenvironment at different adenosine levels. In addition, we analyzed the potential biological pathways engaged by adenosine. Next, we established single-cell transcriptional profiles of LUAD and analyzed cellular composition and cell-cell communication analysis under different adenosine microenvironments. Moreover, we established adenosine-related prognostic signatures (ARS) based on comprehensive bioinformatics analysis and evaluated the efficacy of ARS in predicting immunotherapy. The results demonstrated that adenosine signaling adversely impacted the survival of immune-enriched LUAD. The high-adenosine microenvironment exhibited elevated pro-tumor-immune infiltration, including M2 macrophages and displayed notably increased epithelial-mesenchymal transition (EMT) transformation. Furthermore, adenosine signaling displayed significant associations with the expression patterns and prognostic value of immunomodulators within the TME. Single-cell sequencing data revealed increased fibroblast occupancy and a prominent activation of the SPP1 signaling pathway in the high adenosine-signaling microenvironment. The ARS exhibited promising effectiveness in prognostication and predicting immunotherapy response in LUAD. In summary, overexpression of adenosine can cause a worsened prognosis in the LUAD with abundant immune infiltration. Moreover, increased adenosine levels are associated with pro-tumor-immune infiltration, active EMT transformation, pro-tumor angiogenesis, and other factors promoting cancer progression, which collectively contribute to the formation of an immunosuppressive microenvironment. Importantly, the ARS developed in this study demonstrate high efficacy in evaluating the response to immunotherapy.

Targeting tumor-associated macrophage: an adjuvant strategy for lung cancer therapy

The emergence of immunotherapy has revolutionized the treatment landscape for various types of cancer. Nevertheless, lung cancer remains one of the leading causes of cancer-related mortality worldwide due to the development of resistance in most patients. As one of the most abundant groups of immune cells in the tumor microenvironment (TME), tumor-associated macrophages (TAMs) play crucial and complex roles in the development of lung cancer, including the regulation of immunosuppressive TME remodeling, metabolic reprogramming, neoangiogenesis, metastasis, and promotion of tumoral neurogenesis. Hence, relevant strategies for lung cancer therapy, such as inhibition of macrophage recruitment, TAM reprograming, depletion of TAMs, and engineering of TAMs for drug delivery, have been developed. Based on the satisfactory treatment effect of TAM-targeted therapy, recent studies also investigated its synergistic effect with current therapies for lung cancer, including immunotherapy, radiotherapy, chemotherapy, anti-epidermal growth factor receptor (anti-EGFR) treatment, or photodynamic therapy. Thus, in this article, we summarized the key mechanisms of TAMs contributing to lung cancer progression and elaborated on the novel therapeutic strategies against TAMs. We also discussed the therapeutic potential of TAM targeting as adjuvant therapy in the current treatment of lung cancer, particularly highlighting the TAM-centered strategies for improving the efficacy of anti-programmed cell death-1/programmed cell death-ligand 1 (anti-PD-1/PD-L1) treatment.

The Immune Regulatory Role of Adenosine in the Tumor Microenvironment

Adenosine, an immunosuppressive metabolite, is produced by adenosine triphosphate (ATP) released from dying or stressed cells and is found at high levels in the tumor microenvironment of most solid tumors. It mediates pro-tumor activities by inducing tumor cell proliferation, migration or invasion, tumor tissue angiogenesis, and chemoresistance. In addition, adenosine plays an important role in regulating anti-tumor immune responses and facilitating tumor immune escape. Adenosine receptors are broadly expressed by tumor-infiltrated immune cells, including suppressive tumor-associated macrophages and CD4+ regulatory T cells, as well as effector CD4+ T cells and CD8+ cytotoxic T lymphocytes. Therefore, adenosine is indispensable in down-regulating anti-tumor immune responses in the tumor microenvironment and contributes to tumor progression. This review describes the current progress on the role of adenosine/adenosine receptor pathway in regulating the tumor-infiltrating immune cells that contribute to tumor immune evasion and aims to provide insights into adenosine-targeted tumor immunotherapy.