Blocking the CCL5-CCR5 Axis Using Maraviroc Promotes M1 Polarization of Macrophages Cocultured with Irradiated Hepatoma Cells

The CCL5/CCR5 axis in ulcerative colitis

Ulcerative colitis (UC) is a chronic nonspecific inflammatory bowel disease characterized mainly by inflammatory changes in the intestinal mucosa. While the specific etiology of UC remains unclear, it is generally believed that it is related to many factors, among which the imbalance in the expression of molecules involved in pro-inflammatory and anti-inflammatory processes can lead to UC. CCL5 (C-C chemokine ligand 5) is one of the key pro-inflammatory factors and plays an indispensable role in various inflammatory diseases, including UC. CCL5 binds and activates the receptor CCR5 (C-C chemokine receptor type 5), which in turn, promotes signaling pathways such as PI3K/AKT, NF-κB, and Ras/MAPK, playing an important role in the pathogenesis of UC. The focus of this paper is on the function of the CCL5/CCR5 axis and its subsequent signaling pathways in UC therapy. In addition to this, the article further explores the possible healing benefits of CCR5 antagonists and agonists aimed at the CCL5/CCR5 axis for UC treatment.

CCL5/CCR5/CYP1A1 pathway prompts liver cancer cells to survive in the combination of targeted and immunological therapies

Combination therapy of anti-programmed cell death protein-1 (PD-1) antibodies and tyrosine kinase inhibitors (TKIs) has significantly improved the prognosis for hepatocellular carcinoma (HCC), but many patients still have unsatisfactory outcomes. CD8 T cells are known to exert a pivotal function in the immune response against tumors. Nevertheless, most CD8 T cells in HCC tissues are in a state of exhaustion, losing the cytotoxic activity against malignant cells. Cytokines, mainly secreted by immune cells, play an important role in the occurrence and development of tumors. Here, we demonstrated the changes in exhausted CD8T cells during combination therapy by single-cell RNA sequencing (scRNA-seq) analysis on tumor samples before and after treatment. Combination therapy exerted a substantial impact on the exhausted CD8T cells, particularly in terms of cytokine expression. CCL5 was the most abundantly expressed cytokine in CD8T cells and exhausted CD8T cells, and its expression increased further after treatment. Subsequently, we discovered the CCL5/CCR5/CYP1A1 pathway through RNA sequencing (RNA-seq) on CCL5-stimulated Huh7 cells and verified through a series of experiments that this pathway can mediate the resistance of liver cancer cells to lenvatinib. Tissue experiments showed that after combination therapy, the CCL5/CCR5/CYP1A1 pathway was activated, which can benefit the residual tumor cells to survive treatment. Tumor-bearing mouse experiments demonstrated that bergamottin (BGM), a competitive inhibitor of CYP1A1, can enhance the efficacy of both lenvatinib and combination therapy. Our research revealed one mechanism by which hepatoma cells can survive the combination therapy, providing a theoretical basis for the refined treatment of HCC.

The mechanism of cytokine regulation of cancer occurrence and development in the tumor microenvironment and its application in cancer treatment: a narrative review

Background and Objective

The occurrence and development of tumors in human tissues widely depend on their surrounding environment, known as the tumor microenvironment (TME), which comprises various cells, molecules, and blood vessels. Through modifications, organization, and integration, these elements serve as potential therapeutic targets in anti-cancer therapy, supporting and promoting the proliferation, invasion, and metabolism of tumor cells. Cytokines within TME are responsible for immune cell activation, proliferation, and differentiation, thereby influencing the tumor's behavior. This article reviews the use of cytokines in tumor immunotherapy and combs the network signals that cytokines mediate in the development of malignancies.

Methods

A literature search of international sources was carried out on the PubMed and Web of Science databases, using main keywords such as "tumor immunotherapy", "cytokines", "chemokines", "tumor microenvironment", "recombinant cytokine engineering", and "tumor necrosis factor superfamily".

Key Content and Findings

The review provides a thorough summary of the functions of tumor necrosis factor superfamilies, chemokines, and interleukins within the TME as well as their therapeutic uses. Their potential as novel targets for tumor treatment is also evaluated. Furthermore, this paper focuses on various feasible strategies for recombinant cytokines reported in recent years, especially the cytokine engineering methods for targeting tumors. Ultimately, this paper contributes to an enhanced understanding among researchers of the mechanisms underlying the impact of the TME on disease development, thereby laying a solid foundation for the future development of new tumor therapies based on cytokines within the TME.

Conclusions

Cytokine immunotherapy holds promise on antitumor therapy. It is anticipated that the effectiveness of tumor treatment and the quality of life for tumor patients will continue to improve with ongoing research and development in this field.

Mechanism of Lian Hua Qing Wen capsules regulates the inflammatory response caused by M1 macrophage based on cellular experiments and computer simulations

PURPOSE

The polarization of macrophages with the resulting inflammatory response play a crucial part in tissue and organ damage due to inflammatory. Study has proved Lian Hua Qing Wen capsules (LHQW) can reduce activation of inflammatory response and damage of tissue derived from the inflammatory reactions. However, the mechanism of LHQW regulates the macrophage-induced inflammatory response is unclear. Therefore, we investigated the mechanism of LHQW regulated the inflammatory response of M1 macrophages by cellular experiments and computer simulations.

METHODS

This study has analysed the targets and mechanisms of macrophage regulating inflammatory response at gene and protein levels through bioinformatics. The monomeric components of LHQW were analyzed by High Performance Liquid Chromatography (HPLC). We established the in vitro cell model by M1 macrophages (Induction of THP-1 cells into M1 macrophages). RT-qPCR and immunofluorescence were used to detect changes in gene and protein levels of key targets after LHQW treatment. Computer simulations were utilized to verify the binding stability of monomeric components and protein targets.

RESULTS

Macrophages had 140,690 gene targets, inflammatory response had 12,192 gene targets, intersection gene targets were 11,772. Key monomeric components (including: Pinocembrin, Fargesone-A, Nodakenin and Bowdichione) of LHQW were screened by HPLC. The results of cellular experiments indicated that LHQW could significantly reduce the mRNA expression of CCR5, CSF2, IFNG and TNF, thereby alleviating the inflammatory response caused by M1 macrophage. The computer simulations further validated the binding stability and conformation of key monomeric components and key protein targets, and IFNG/Nodakenin was able to form the most stable binding conformation for its action.

CONCLUSION

In this study, the mechanism of LHQW inhibits the polarization of macrophages and the resulting inflammatory response was investigated by computer simulations and cellular experiments. We found that LHQW may not only reduce cell damage and death by acting on TNF and CCR5, but also inhibit the immune recognition process and inflammatory response by regulating CSF2 and IFNG to prevent polarization of macrophages. Therefore, these results suggested that LHQW may act through multiple targets to inhibit the polarization of macrophages and the resulting inflammatory response.

Correlation of Immunomodulatory Cytokines with Tumor Volume and Cerebrospinal Fluid in Vestibular Schwannoma Patients

Sporadic vestibular schwannomas (VSs) often exhibit slow or negligible growth. Nevertheless, some VSs increase significantly in volume within a few months or grow continuously. Recent evidence indicates a role of inflammation in promoting VS growth. Therefore, our study aimed to identify cytokines, which are associated with larger VSs. The expression of different cytokines in VS tumor samples and VS primary cultures was investigated. Additionally, the concentration of cytokines in cell culture supernatants of VS primary cultures and cerebrospinal fluid (CSF) of VS patients and healthy controls were determined. Correlation analysis of cytokine levels with tumor volume, growth rate, Koos grade, age, and hearing was examined with Spearman's-rank test. The mRNA expression of CC-chemokine ligand (CCL) 18, growth differentiation factor (GDF) 15, and interferon regulatory factor 4 correlated positively with tumor volume. Moreover, the amount of GDF15 in the cell culture supernatant of primary cells correlated positively with tumor volume. The concentrations of the cytokines CCL2, CCL5, and CCL18 and transforming growth factor beta (TGFB) 1 in the CSF of the patients were significantly different from those in the CSF controls. Inhibition of immune cell infiltration could be a putative approach to prevent and control VS growth.

The Aconitate Decarboxylase 1/Itaconate Pathway Modulates Immune Dysregulation and Associates with Cardiovascular Disease Markers and Disease Activity in Systemic Lupus Erythematosus

The Krebs cycle enzyme aconitate decarboxylase 1 (ACOD1) mediates itaconate synthesis in monocytes and macrophages. Previously, we reported that administration of 4-octyl itaconate to lupus-prone mice abrogated immune dysregulation and clinical features. In this study, we explore the role of the endogenous ACOD1/itaconate pathway in the development of TLR7-induced lupus (imiquimod [IMQ] model). We found that, in vitro, ACOD1 was induced in mouse bone marrow-derived macrophages and human monocyte-derived macrophages following TLR7 stimulation. This induction was partially dependent on type I IFN receptor signaling and on specific intracellular pathways. In the IMQ-induced mouse model of lupus, ACOD1 knockout (Acod1-/-) displayed disruptions of the splenic architecture, increased serum levels of anti-dsDNA and proinflammatory cytokines, and enhanced kidney immune complex deposition and proteinuria, when compared with the IMQ-treated wild-type mice. Consistent with these results, Acod1-/- bone marrow-derived macrophages treated in vitro with IMQ showed higher proinflammatory features. Furthermore, itaconate serum levels in systemic lupus erythematosus patients were decreased compared with healthy individuals, in association with disease activity and specific perturbed cardiometabolic parameters. These findings suggest that the ACOD1/itaconate pathway plays important immunomodulatory and vasculoprotective roles in systemic lupus erythematosus, supporting the potential therapeutic role of itaconate analogs in autoimmune diseases.

The role of tumor-associated macrophages in hepatocellular carcinoma-from bench to bedside: A review

Hepatocellular carcinoma is one of the most common cancers worldwide. Despite progress in treatment, recurrence after radical treatment is common, and the prognosis remains poor for patients with advanced disease. Therefore, there is a need to identify prognostic and predictive factors for the response to therapy or more intensive surveillance or treatment. Because the tumor microenvironment plays a crucial role in the development of cancer and metastasis, it is a crucial need to understand processes that are involved in carcinogenesis. Within the microenvironment, several immune cells with different roles are present. One of the most important of these is tumor-associated macrophages. These cells may exert either antitumor or protumor roles. Several studies have suggested that tumor-associated macrophages can be used as prognostic markers. Furthermore, they may be involved in resistance to immunotherapy or systemic treatment. As they play an important role in cancer development, tumor-associated macrophages are also a good target for therapy. In this review, we briefly summarize recent progress on knowledge regarding the basic molecular characteristics, impact on prognosis and potential clinical implications of tumor-associated macrophages in hepatocellular carcinoma.

CDDP-induced desmoplasia-like changes in oral cancer tissues are related to SASP-related factors induced by the senescence of cancer cells

The tumor microenvironment (TME) concept has been proposed and is currently being actively studied. The development of extracellular matrix (ECM) in the TME is known as desmoplasia and is observed in many solid tumors. It has also been strongly associated with poor prognosis and resistance to drug therapy. Recently, cellular senescence has gained attention as an effect of drug therapy on cancer cells. Cellular senescence is a phenomenon wherein proliferating cells become resistant to growth-promoting stimuli, secrete the SASP (senescence-associated phenotypic) factors, and stably arrest the cell cycle. These proteins are rich in pro-inflammatory factors, such as interleukin (IL)-6, IL-8, C-X-C motif chemokine ligand 1, C-C motif chemokine ligand (CCL)2, CCL5, and matrix metalloproteinase 3. This study aimed to investigate the desmoplasia-like changes in the TME before and after cancer drug therapy in oral squamous cell carcinomas, evaluate the effect of anticancer drugs on the TME, and the potential involvement of cancer cell senescence. Using a syngeneic oral cancer transplant mouse model, we confirmed that cis-diamminedichloroplatinum (II) (CDDP) administration caused desmoplasia-like changes in cancer tissues. Furthermore, CDDP treatment-induced senescence in tumor-bearing mouse tumor tissues and cultured cancer cells. These results suggest CDDP administration-induced desmoplasia-like structural changes in the TME are related to cellular senescence. Our findings suggest that the administration of anticancer drugs alters the TME of oral cancer cells. Additionally, oral cancer cells undergo senescence, which may influence the TME through the production of SASP factors.

Macrophages as Targets in Hepatocellular Carcinoma Therapy

Hepatocellular carcinoma (HCC) is a malignant tumor with a complex and diverse immunosuppressive microenvironment. Tumor-associated macrophages (TAM) are an essential component of the tumor immune microenvironment. TAMs typically exist in two primary states: anti-tumor M1 macrophages and protumor M2 macrophages. Remarkably, TAMs possess high plasticity, enabling them to switch between different subtypes or alter their biological functions in response to the tumor microenvironment. Based on research into the biological role of TAMs in the occurrence and development of malignant tumors, including HCC, TAMs are emerging as promising targets for novel tumor treatment strategies. In this review, we provide a detailed introduction to the origin and subtypes of TAMs, elucidate their interactions with other cells in the complex tumor microenvironment of HCC, and describe the biological roles, characteristics, and mechanisms of TAMs in the progression of HCC. Furthermore, we furnish an overview of the latest therapeutic strategies targeting TAMs.

The aconitate decarboxylase 1/itaconate pathway modulates immune dysregulation and associates with cardiovascular disease markers in SLE

Objective

The Krebs cycle enzyme Aconitate Decarboxylase 1 (ACOD1) mediates itaconate synthesis in myeloid cells.. Previously, we reported that administration of 4-octyl itaconate abrogated lupus phenotype in mice. Here, we explore the role of the endogenous ACOD1/itaconate pathway in the development of murine lupus as well as their relevance in premature cardiovascular damage in SLE.

Methods

We characterized Acod1 protein expression in bone marrow-derived macrophages and human monocyte-derived macrophages, following a TLR7 agonist (imiquimod, IMQ). Wild type and Acod1-/- mice were exposed to topical IMQ for 5 weeks to induce an SLE phenotype and immune dysregulation was quantified. Itaconate serum levels were quantified in SLE patients and associated to cardiometabolic parameters and disease activity.

Results

ACOD1 was induced in mouse bone marrow-derived macrophages (BMDM) and human monocyte-derived macrophages following in vitro TLR7 stimulation. This induction was partially dependent on type I Interferon receptor signaling and specific intracellular pathways. In the IMQ-induced mouse model of lupus, ACOD1 knockout (Acod1-/-) displayed disruptions of the splenic architecture, increased serum anti-dsDNA and proinflammatory cytokine levels, enhanced kidney immune complex deposition and proteinuria, when compared to the IMQ-treated WT mice. Consistent with these results, Acod1-/- BMDM exposed to IMQ showed higher proinflammatory features in vitro. Itaconate levels were decreased in SLE serum compared to healthy control sera, in association with specific perturbed cardiometabolic parameters and subclinical vascular disease.

Conclusion

These findings suggest that the ACOD1/itaconate pathway plays important immunomodulatory and vasculoprotective roles in SLE, supporting the potential therapeutic role of itaconate analogs in autoimmune diseases.

Tumor-associated macrophages: an effective player of the tumor microenvironment

Cancer progression is primarily caused by interactions between transformed cells and the components of the tumor microenvironment (TME). TAMs (tumor-associated macrophages) make up the majority of the invading immune components, which are further categorized as anti-tumor M1 and pro-tumor M2 subtypes. While M1 is known to have anti-cancer properties, M2 is recognized to extend a protective role to the tumor. As a result, the tumor manipulates the TME in such a way that it induces macrophage infiltration and M1 to M2 switching bias to secure its survival. This M2-TAM bias in the TME promotes cancer cell proliferation, neoangiogenesis, lymphangiogenesis, epithelial-to-mesenchymal transition, matrix remodeling for metastatic support, and TME manipulation to an immunosuppressive state. TAMs additionally promote the emergence of cancer stem cells (CSCs), which are known for their ability to originate, metastasize, and relapse into tumors. CSCs also help M2-TAM by revealing immune escape and survival strategies during the initiation and relapse phases. This review describes the reasons for immunotherapy failure and, thereby, devises better strategies to impair the tumor-TAM crosstalk. This study will shed light on the understudied TAM-mediated tumor progression and address the much-needed holistic approach to anti-cancer therapy, which encompasses targeting cancer cells, CSCs, and TAMs all at the same time.

Programming Cell-Derived Vesicles with Enhanced Immunomodulatory Properties

Tumor-associated macrophages are the predominant immune cells present in the tumor microenvironment and mostly exhibit a pro-tumoral M2-like phenotype. However, macrophage biology is reversible allowing them to acquire an anti-tumoral M1-like phenotype in response to external stimuli. A potential therapeutic strategy for treating cancer may be achieved by modulating macrophages from an M2 to an M1-like phenotype with the tumor microenvironment. Here, programmed nanovesicles are generated as an immunomodulatory therapeutic platform with the capability to re-polarize M2 macrophages toward a proinflammatory phenotype. Programmed nanovesicles are engineered from cellular membranes to have specific immunomodulatory properties including the capability to bidirectionally modulate immune cell polarization. These programmed nanovesicles decorated with specific membrane-bound ligands can be targeted toward specific cell types including immune cells. Macrophage-derived vesicles are engineered to enhance immune cell reprogramming toward a proinflammatory phenotype.

Role of chemokines in the crosstalk between tumor and tumor-associated macrophages

Tumor microenvironment (TME) consists of a dynamic network of non-tumoral stromal cells, including cancer-associated fibroblasts, endothelial cells, tumor-associated macrophages (TAMs), B and T cells. In the TME, TAMs support tumor initiation, progression, invasion and metastasis by promoting angiogenesis and immunosuppression of the tumor cells. There is close crosstalk between TAMs and tumor cells. Notably, chemokines are a significant messenger mediating the crosstalk between tumor cells and TAMs. TAMs can promote tumor progression via secretion of chemokines. Various chemokines secreted by tumors are involved in the generation and polarization of TAMs, the infiltration of TAMs in tumors, and the development of TAMs' suppressive function. This paper reviews CCL2-CCR2, CCL3/5-CCR5, CCL15-CCR1, CCL18-CCR8, CX3CL1/CCL26-CX3CR1, CXCL8-CXCR1/2, CXCL12-CXCR4/CXCR7 signaling pathways, their role in the recruitment, polarization and exertion of TAMs, and their correlation with tumor development, metastasis and prognosis. Furthermore, we present the current research progress on modulating the effects of TAMs with chemokine antagonists and discuss the prospects and potential challenges of using chemokine antagonists as therapeutic tools for cancer treatment. The TAMs targeting by chemokine receptor antagonists in combination with chemotherapy drugs, immune checkpoint inhibitors or radiotherapy appears to be a promising approach.

The anti-hepatocellular carcinoma effects of polysaccharides from Ganoderma lucidum by regulating macrophage polarization via the MAPK/NF-κB signaling pathway

The response of macrophages to environmental signals demonstrates its heterogeneity and plasticity. After different forms of polarized activation, macrophages reach the M1 or M2 activation state according to their respective environment. Ganoderma lucidum polysaccharide (GLPS) is a major bioactive component of Ganoderma lucidum, a well-known medicinal mushroom. Although the immunomodulatory and anti-tumor effects of GLPS have been proven, GLPS's effect on inhibiting hepatocellular carcinoma (HCC) by regulating macrophage polarization is little known. Our data showed that GLPS notably inhibited the growth of a Hepa1-6 allograft. The expression of M1 marker CD86 was higher in the tumor tissue of the GLPS treatment group than in the control group in vivo. In vitro, the phagocytic activity and NO production of macrophages were increased by GLPS treatment. Moreover, it was discovered that GLPS was able to increase the expression of the M1 phenotype marker CD86, iNOS, and pro-inflammatory cytokines comprising IL-12a, IL-23a, IL-27 and TNF-α, but inhibited macrophage polarization towards the M2 phenotype by decreasing the expression of CD206, Arg-1, and inflammation-related cytokines comprising IL-6 and IL-10. The data suggest that GLPS may regulate macrophage polarization. Mechanistically, GLPS increased the phosphorylation of MEK and ERK. In addition, the phosphorylation of IκBα and P65 was increased by GLPS treatment. These data showed that GLPS can regulate the MAPK/NF-κB signaling pathway responsible for M1 polarization. In a nutshell, our research puts forward a new application of GLPS in anti-HCC treatment by regulating macrophage polarization through activating MAPK/NF-κB signaling.

The paradoxical role of radiation-induced cGAS-STING signalling network in tumour immunity

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is an essential component of the innate immune system and is central to the identification of abnormal DNA leakage caused by ionising radiation (IR) damage. Cell-intrinsic cGAS-STING initiation has been revealed to have tremendous potential for facilitating interferon synthesis and T-cell priming. Targeting the cGAS-STING axis has been proposed as a strategy to improve radiosensitivity or enhance immunosurveillance. However, due to the complex biology of the irradiated tumour microenvironment and the extensive involvement of the cGAS-STING pathway in various physiological and pathological processes, many defects in this strategy limit the therapeutic effect. Here, we outline the molecular mechanisms by which IR activates the cGAS-STING pathway and analyse the dichotomous roles of the cGAS-STING pathway in modulating cancer immunity after radiotherapy (RT). Then, based on the crosstalk between the cGAS-STING pathway and other signalling events induced by IR, such as necroptosis, autophagy and other cellular effects, we discuss the immunomodulatory actions of the broad cGAS-STING signalling network in RT and their potential therapeutic applications. Finally, recent advances in combination therapeutic strategies targeting cGAS-STING in RT are explored.

Targeting tumor-associated macrophages in hepatocellular carcinoma: biology, strategy, and immunotherapy

Hepatocellular carcinoma (HCC), one of the most malignant tumors, is characterized by its stubborn immunosuppressive microenvironment. As one of the main members of the tumor microenvironment (TME) of HCC, tumor-associated macrophages (TAMs) play a critical role in its occurrence and development, including stimulating angiogenesis, enhancing immunosuppression, and promoting the drug resistance and cancer metastasis. This review describes the origin as well as phenotypic heterogeneity of TAMs and their potential effects on the occurrence and development of HCC and also discusses about various adjuvant therapy based strategies that can be used for targeting TAMs. In addition, we have highlighted different treatment modalities for TAMs based on immunotherapy, including small molecular inhibitors, immune checkpoint inhibitors, antibodies, tumor vaccines, adoptive cellular immunotherapy, and nanocarriers for drug delivery, to explore novel combination therapies and provide feasible therapeutic options for clinically improving the prognosis and quality of life of HCC patients.

Metabolic effects of CCL5 deficiency in lean and obese mice

Accumulation and activation of immunocytes in adipose tissues are essential to obesity-induced inflammation and insulin resistance. Chemokines are pivotal for the recruitment of immunocytes in adipose tissue during obesity. Chemokine (C-C motif) ligand 5 (CCL5) plays a vital role in the recruitment of immunocytes to sites of inflammation. CCL5 expression level is increased in obese adipose tissue from humans and mice. However, the role of CCL5 in obesity-induced adipose inflammation remains unclear. Our study found that the CCL5 expression level was increased in the epididymal white adipose tissue (eWAT) of obese mice, particularly in CD8⁺ T cells. CCL5 knockout (KO) mice exhibited better glucose tolerance than wild-type (WT) mice under lean conditions. In contrast, CCL5 KO mice were more insulin resistant and had severe hepatic steatosis than WT mice under obese conditions. Increased T cells in adipose tissue heaven adipose inflammation in obese CCL5 KO mice. The compensatory increased T cell-associated chemokines may account for increased T cell content in the eWAT of obese CCL5 KO mice. These findings imply that CCL5 deficiency exacerbates adipose inflammation and impairs insulin sensitivity in the metabolic tissues of obese mice.

Targeting CCL5 signaling attenuates neuroinflammation after seizure

BACKGROUND

Epilepsy is a neurological condition that causes unprovoked, recurrent seizures. Accumulating evidence from clinical and experimental studies indicates that neuroinflammation exacerbates seizure activity.

METHODS

We investigated the transcriptional changes occurring in specific brain domains of a seizure mouse model, using 10× Genomics spatial transcriptomics. Differential gene expression and pathway analysis were applied to investigate potential signaling targets for seizure, including CCL5/CCR5 pathway. Maraviroc, an FDA-approved C-C chemokine receptor 5 (CCR5) antagonist, was used to verify the impact of CCL5/CCR5 signaling in seizure mice.

RESULTS

We found distinguished regional transcriptome features in the hippocampus of seizure mice. The hippocampus exhibited unique inflammatory gene signatures, including glia activation, apoptosis, and immune response in seizure mice. Especially, we observed notable expression of C-C chemokine ligand 5 (CCL5) throughout the entire seizure hippocampus. Blockade of CCL5/CCR5 signaling via maraviroc prevented microglia activation and neuron degeneration in seizure mice.

CONCLUSIONS

This study supports the potential of CCL5/CCR5 signaling for targeting neuroinflammation after seizure.

Major pathways involved in macrophage polarization in cancer

Macrophages play an important role in tissue homeostasis, tissue remodeling, immune response, and progression of cancer. Consequently, macrophages exhibit significant plasticity and change their transcriptional profile and function in response to environmental, tissue, and inflammatory stimuli resulting in pro- and anti-tumor effects. Furthermore, the categorization of tissue macrophages in inflammatory situations remains difficult; however, there is an agreement that macrophages are predominantly polarized into two different subtypes with pro- and anti-inflammatory properties, the so-called M1-like and M2-like macrophages, respectively. These two macrophage classes can be considered as the extreme borders of a continuum of many intermediate subsets. On one end, M1 are pro-inflammatory macrophages that initiate an immunological response, damage tissue integrity, and dampen tumor progression by fostering robust T and natural killer (NK) cell anti-tumoral responses. On the other end, M2 are anti-inflammatory macrophages involved in tissue remodeling and tumor growth, that promote cancer cell proliferation, invasion, tumor metastasis, angiogenesis and that participate to immune suppression. These decisive roles in tumor progression occur through the secretion of cytokines, chemokines, growth factors, and matrix metalloproteases, as well as by the expression of immune checkpoint receptors in the case of M2 macrophages. Moreover, macrophage plasticity is supported by stimuli from the Tumor Microenvironment (TME) that are relayed to the nucleus through membrane receptors and signaling pathways that result in gene expression reprogramming in macrophages, thus giving rise to different macrophage polarization outcomes. In this review, we will focus on the main signaling pathways involved in macrophage polarization that are activated upon ligand-receptor recognition and in the presence of other immunomodulatory molecules in cancer.

Macrophages Are a Double-Edged Sword: Molecular Crosstalk between Tumor-Associated Macrophages and Cancer Stem Cells

Cancer stem cells (CSCs) are a subset of highly tumorigenic cells in tumors. They have enhanced self-renewal properties, are usually chemo-radioresistant, and can promote tumor recurrence and metastasis. They can recruit macrophages into the tumor microenvironment and differentiate them into tumor-associated macrophages (TAMs). TAMs maintain CSC stemness and construct niches that are favorable for CSC survival. However, how CSCs and TAMs interact is not completely understood. An understanding on these mechanisms can provide additional targeting strategies for eliminating CSCs. In this review, we comprehensively summarize the reported mechanisms of crosstalk between CSCs and TAMs and update the related signaling pathways involved in tumor progression. In addition, we discuss potential therapies targeting CSC–TAM interaction, including targeting macrophage recruitment and polarization by CSCs and inhibiting the TAM-induced promotion of CSC stemness. This review also provides the perspective on the major challenge for developing potential therapeutic strategies to overcome CSC-TAM crosstalk.

NR4A2 alleviates cardiomyocyte loss and myocardial injury in rats by transcriptionally suppressing CCR5 and inducing M2 polarization of macrophages

BACKGROUND

CC chemokine receptor 5 (CCR5) has been demonstrated to be correlated to activation of pro-inflammatory immune cells and tissue injury. This study focused on the role of CCR5 in myocardial injury in rats with diabetic cardiomyopathy (DCM) and the mechanism of action.

METHODS

A rat model of DCM was induced by streptozotocin (STZ). CCR5 was knocked down in rats to determine its role in myocardial injury and immune cell infiltration. The upstream regulators of CCR5 were bioinformatically predicted and the binding between nuclear receptor subfamily 4 group A member 2 (NR4A2) and CCR5 was validated. The portion of M1 and M2 macrophages in tissues was determined by flow cytometry or double-labeling immunofluorescence. Rat bone marrow mononuclear cells (BMMCs) were treated with granulocyte/macrophage colony stimulating factor (GM-CSF/M-CSF) and co-cultured with H9C2 cells for in vitro experiments.

RESULTS

STZ-treated rats had impaired cardiac function and increased levels of creatine kinase-MB, cardiac troponin I and lactate dehydrogenase. CCR5 inhibition significantly alleviated myocardial injury in rats and reduced the portion of M1 macrophages in rat cardiac tissues. NR4A2, which could suppress CCR5 transcription, was poorly expressed in rats with DCM. NR4A2 overexpression played a similar myocardium-protective role in rats. In vitro, overexpression of NR4A2 induced M2 polarization of macrophages, which protected the co-cultured H9C2 cells from high glucose-induced damage, but the protective role was blocked after CCR5 overexpression.

CONCLUSION

This study demonstrated that NR4A2 suppresses CCR5 expression and promotes M2 polarization of macrophages to alleviate cardiomyocyte loss and myocardial injury.

CCR1 and CCR5 mediate cancer-induced myelopoiesis and differentiation of myeloid cells in the tumor

Background

Cancer-induced ‘emergency’ myelopoiesis plays a key role in tumor progression by inducing the accumulation of myeloid cells with a suppressive phenotype peripherally and in the tumor. Chemokine receptors (CCRs) and, in particular, CCR1, CCR2, CCR5, and CCR7 are emerging as key regulators of myeloid cell trafficking and function but their precise role has not been completely clarified yet because of the signal redundancy, integration, and promiscuity of chemokines and of the expression of these CCRs on other leukocyte subsets.

Methods

We used the 4PD nanoparticle for the in vivo targeted silencing of CCR1, CCR2, CCR5, and/or CCR7 in the myeloid cells of tumor bearing mice to evaluate the effect of treatments on tumor growth, myeloid cell trafficking and polarization. We used flow and image cytometry and functional assays to monitor changes in the tumor microenvironment and depletion experiments and immune deficient mice to determine the role of Ly6G⁺cells during tumor progression. We further evaluated in vitro the impact of chemokine receptor inhibition and tumor derived factors on myeloid cell differentiation from mouse and human hematopoietic stem and precursors cells (HSPCs) using flow cytometry, transcriptome analysis, cytokines beads arrays, functional assays, and mice deficient for CCR1 or CCR5.

Results

4PD-mediated in vivo silencing of CCR1 and CCR5 on myeloid cells and myeloid precursors was necessary and sufficient to inhibit tumor progression. Functional studies indicated that this antitumor effect was not mediated by alteration of myeloid cell chemotaxes but rather by the repolarization of polymorphonuclear myeloid-derived suppressor cells (MDSCs) into tumoricidal neutrophils. Transcriptome functional and cytokine analysis indicated that tumor derived factors induced CCL3 and CCL4 in HSPCs that, through the autocrine engagement of CCR1 and CCR5, induced HSPCs differentiation in MDSCs. These finding were confirmed across mice with different genetic backgrounds and using HSPCs from umbilical cord blood and peripheral blood of patients with cancer.

Conclusions

Our data support the notion that CCR1 and CCR5 and their ligands are a master immunological hub activated by several tumor derived factors. Activation of this pathway is necessary for the differentiation of MDSCs and protumoral macrophages.

Neutrophil gelatinase-associated lipocalin as an immunomodulator in endocrine hypertension

In recent studies, primary aldosteronism (PA) has been reported as the most common etiology for secondary hypertension of endocrine origin, accounting for approximately 10% of cases. In PA, excess aldosterone production can lead to deleterious effects at the cardiovascular (CV) and renal levels by activating mineralocorticoid receptors, which involves an increase in pro-inflammatory and pro-fibrotic mediators. Among these mediators, neutrophil gelatinase-associated lipocalin (NGAL), a secretion glycoprotein belonging to the lipocalin superfamily, has been closely linked to CV and renal damage in several pathological conditions. Because NGAL can be detected in biofluids such as plasma and urine, it has been proposed as a damage biomarker for target tissues and has also been studied for its role in hypertension and associated with PA. NGAL is produced by many different cell types, can be carried on extracellular vesicles, and is modulated by microRNAs, which would support its use as a biomarker for endocrine hypertension due to PA. Over the last decade, studies have shown that NGAL is necessary for the development of aldosterone-induced hypertension and that is associated with end-organ damage. In addition, it has been proposed that some mechanisms are dependent on the activation of immune cells, such as dendritic cells and macrophages, where the release of specific cytokines (i.e., interleukin [IL]-23) or chemokines (i.e., CCL-5) induced by aldosterone would depend on NGAL. Subsequently, this activates the T helper (Th) lymphocytes, such as Th₁₇ and Th₂, resulting in CV and renal fibrosis due to the high aldosterone levels. Although the immune system has been closely associated with essential hypertension, its participation in endocrine hypertension has not been fully elucidated. This review discusses the link between NGAL and endocrine hypertension, particularly in the context of PA, and their possible regulators and mechanisms, with a focus on its role as an immunomodulator.