The IL-33/ST2 axis affects tumor growth by regulating mitophagy in macrophages and reprogramming their polarization

Adventitial Injection of Hyaluronic Acid/Sodium Alginate Hydrogel Loaded With IL-33 Antibody Decreases Neointimal Hyperplasia

INTRODUCTION

Neointimal hyperplasia is one of the persistent complications after vascular interventions, and is the major cause of treatment failure. Interleukin-33 (IL-33) emerges as a crucial factor in many biological processes and plays an important role in vascular diseases. Adventitial injection is catching attention for its effectiveness and fewer side effects. We hypothesize that targeting IL-33 by adventitial injection can be a therapeutic method to inhibit neointimal hyperplasia.

METHOD

IL-33 expression was examined in human vein graft. The hydrogel was fabricated by the interaction of hyaluronic acid, sodium alginate, and CaCO3; and phosphate buffered saline (PBS) or IL-33 antibody or recombinant IL-33 was mixed within the hydrogel uniformly. A rat aortic wire injury-induced neointimal hyperplasia model was developed; rats were divided into three groups and received an adventitial injection of a hydrogel loaded with PBS or IL-33 antibody or recombinant IL-33 after wire injury. Tissues were harvested at day 21 and analyzed by histology and immunohistochemical staining. Hydrogel loaded with PBS, IL-33 antibody, or IL-33 was also used in a mouse carotid artery ligation neointimal hyperplasia model.

RESULT

There was a high expression of IL-33 in human vein graft neointima. Hydrogel can be successfully injected into the aortic wall and is encapsulated by the adventitia. The hydrogel could be seen beneath the adventitia after adventitial injection and was partly degraded at day 21. There was a significantly thinner neointimal thickness and less proliferation and inflammation in the IL-33 antibody group compared to the control group. On the contrary, the IL-33 group has a thicker neointima, increased proliferation, and inflammation. The mouse carotid artery ligation model showed similar results.

CONCLUSIONS

IL-33 plays a role in arterial neointimal hyperplasia in both human and rodent models; adventitial injection of hydrogel loaded with IL-33 antibody can effectively decrease neointimal thickness. Neutralizing IL-33 by IL-33 antibody may be a potential therapeutic method to inhibit intimal hyperplasia after vascular interventions.

Mitochondrial quality control in human health and disease

Mitochondria, the most crucial energy-generating organelles in eukaryotic cells, play a pivotal role in regulating energy metabolism. However, their significance extends beyond this, as they are also indispensable in vital life processes such as cell proliferation, differentiation, immune responses, and redox balance. In response to various physiological signals or external stimuli, a sophisticated mitochondrial quality control (MQC) mechanism has evolved, encompassing key processes like mitochondrial biogenesis, mitochondrial dynamics, and mitophagy, which have garnered increasing attention from researchers to unveil their specific molecular mechanisms. In this review, we present a comprehensive summary of the primary mechanisms and functions of key regulators involved in major components of MQC. Furthermore, the critical physiological functions regulated by MQC and its diverse roles in the progression of various systemic diseases have been described in detail. We also discuss agonists or antagonists targeting MQC, aiming to explore potential therapeutic and research prospects by enhancing MQC to stabilize mitochondrial function.

Unremitting pro-inflammatory T-cell phenotypes, and macrophage activity, following paediatric burn injury

Objectives

The aim of this study was to characterise the dynamic immune profile of paediatric burn patients for up to 18 months post-burn.

Methods

Flow cytometry was used to measure 25 cell markers, chemokines and cytokines which reflected both pro-inflammatory and anti-inflammatory immune profiles. Peripheral blood mononuclear cells from 6 paediatric burn patients who had returned for repeated burn and scar treatments for > 4 timepoints within 12 months post-burn were compared to four age-matched healthy controls.

Results

While overall proportions of T cells, NK cells and macrophages remained relatively constant, over time percentages of these immune cells differentiated into effector and proinflammatory cell phenotypes including Th17 and activated γδ T cells. Circulating proportions of γδ T cells increased their expression of pro-inflammatory mediators throughout the burn recovery, with a 3-6 fold increase of IL-17 at 1-3 weeks, and NFκβ 9-18 months post-burn. T-regulatory cell plasticity was also observed, and Treg phenotype proportions changed from systemically reduced skin-homing T-regs (CCR4+) and increased inflammatory (CCR6+) at 1-month post-burn, to double-positive cell types (CCR4+CCR6+) elevated in circulation for 18 months post-burn. Furthermore, Tregs were observed to proportionally express less IL-10 but increased TNF-α over 18 months.

Conclusion

Overall, these results indicate the circulating percentages of immune cells do not increase or decrease over time post-burn, instead they become highly specialised, inflammatory and skin-homing. In this patient population, these changes persisted for at least 18 months post-burn, this 'immune distraction' may limit the ability of immune cells to prioritise other threats post-burn, such as respiratory infections.

The regulatory role of autophagy between TAMs and tumor cells

Cancer has become a global public health problem and its harmful effects have received widespread attention. Conventional treatments such as surgical resection, radiotherapy and other techniques are applicable to clinical practice, but new drugs are constantly being developed and other therapeutic approaches, such as immunotherapy are being applied. In addition to studying the effects on individual tumor cells, it is important to explore the role of tumor microenvironment on tumor cell development since tumor cells do not exist alone but in the tumor microenvironment. In the tumor microenvironment, tumor cells are interconnected with other stromal cells and influence each other, among which tumor-associated macrophages (TAMs) are the most numerous immune cells. At the same time, it was found that cancer cells have different levels of autophagy from normal cells. In cancer therapy, the occurrence of autophagy plays an important role in promoting tumor cell death or inhibiting tumor cell death, and is closely related to the environment. Therefore, elucidating the regulatory role of autophagy between TAMs and tumor cells may be an important breakthrough, providing new perspectives for further research on antitumor immune mechanisms and improving the efficacy of cancer immunotherapy.

Glycolysis regulation in tumor-associated macrophages: Its role in tumor development and cancer treatment

Tumor-associated macrophages constitute the main cell population in the tumor microenvironment and play a crucial role in regulating the microenvironment composition. Emerging evidence has revealed that the metabolic profile determines the tumor-associated macrophage phenotype. Tumor-associated macrophage function is highly dependent on glucose metabolism, with glycolysis being the major metabolic pathway. Recent reports have demonstrated diversity in glucose flux of tumor-associated macrophages and complex substance communication with cancer cells. However, how the glucose flux in tumor-associated macrophages connects with glycolysis to influence tumor progression and the tumor microenvironment is still obscure. Moreover, while the development of single-cell sequencing technology allows a clearer and more accurate classification of tumor-associated macrophages, the metabolic profiles of tumor-associated macrophages from the perspective of single-cell omics has not been well summarized. Here, we review the current state of knowledge on glucose metabolism in tumor-associated macrophages and summarize the metabolic profiles of different tumor-associated macrophage subtypes from the perspective of single-cell omics. Additionally, we describe the current strategies targeting glycolysis in tumor-associated macrophages for cancer therapy.

IL-33/ST2 Signaling and its Correlation with Macrophage Heterogeneity and Clinicopathologic Features in Human Intrahepatic Cholangiocarcinoma

BACKGROUND

IL-33/ST2 signaling plays crucial roles in the development and progression of various human malignancies. However, its significance in intrahepatic cholangiocarcinoma (ICC) still remains unclear.

OBJECTIVE

This study aimed to investigate the expression of IL-33/ST2 signaling and its correlations with macrophage heterogeneity and ICC patients' clinicopathologic features.

METHODS

The expression of different phenotype macrophage markers and IL-33/ST2 signalingrelated markers was detected. The correlation between L-33/ST2 signaling and different phenotype macrophage markers as well as ICC patients' clinicopathologic data was evaluated.

RESULTS

Massive heterogeneous cancer cells and PAS-positive cells were observed in tumor tissues. CD68-positive cells accumulated in tumor tissues and expression of both M1 phenotype markers and M2 phenotype macrophage markers was higher in tumor samples than para-carcinoma samples. However, M2 phenotype macrophages represented the dominant macrophage population in ICC tissues. Plasma levels of IL-33, ST2, and MIF were evidently enhanced in ICC patients compared to healthy controls. IL-33/ST2 signaling-related markers exhibited a massive increase in tumor samples than para-carcinoma samples. IL-33 and ST2 expression in ICC tissues was positively associated with M1 and M2 phenotype macrophages. Plasma levels of IL-33, ST2, and MIF were correlated with the diameter of tumor lesions, lymph node metastasis, TNM stage, and tumor differentiation degree. Multivariate analysis demonstrated IL-33 expression to exhibit a correlation with the diameter of tumor lesions, lymph node metastasis, and TNM stage. Additionally, there was a relationship observed between ST2, MIF expression, and diameter of tumor lesions plus TNM stage.

CONCLUSION

IL-33/ST2 signaling exhibited a positive relationship with macrophage heterogeneity in ICC tissues, and upregulated levels of IL-33, ST2, and MIF were associated with aggressive clinicopathologic characteristics. These findings may provide promising diagnostic biomarkers and potential therapeutic strategies for ICC patients targeting IL-33/ST2 signaling.

MiR-548t-5p regulates pancreatic ductal adenocarcinoma metastasis through an IL-33-dependent crosstalk between cancer cells and M2 macrophages

IL-33 has been associated with pro- and anticancer functions in cancer. However, its role in pancreatic cancer metastasis remains unknown. This study aimed to explore the role of miR-548t-5p/IL-33 axis in the metastasis of pancreatic cancer. Luciferase activity assay, qRT-PCR, Western blot and ELISA were performed to prove whether IL-33 is the target of miR-548t-5p. In vivo metastasis assay and cellular transwell assay were performed to explore the role of miR-548t-5p/IL-33 axis in the invasion and metastasis of pancreatic cancer. Co-culture experiments and immunohistochemistry were performed to observe whether IL-33 affects cell invasion and metastasis dependent on the involvement of M2 macrophages. THP-1 cell induction experiment and flow cytometry were performed to explore the effect of IL-33 on macrophage polarization. CCK-8, colony formation, cell apoptosis, cell cycle, cell wound healing and transwell assay were performed to investigate the effect of IL-33 induced M2 macrophages on cell malignant biological behavior by coculturing pancreatic cancer cells with the conditioned medium (CM) from macrophages. We found that miR-548t-5p regulated the expression and secretion of IL-33 in pancreatic cancer cells by directly targeting IL-33 mRNA. IL-33 secreted by cancer cells promoted the recruitment and activation of macrophages to a M2-like phenotype. In turn, IL-33 induced M2 macrophages promoted the migration and invasion of cancer cells. Moreover, IL-33 affected pancreatic cancer cell invasion dependent on the involvement of M2 macrophages in the co-culture system. Thus, our study suggested that manipulation of this IL-33-dependent crosstalk has a therapeutic potential for the treatment of pancreatic cancer metastasis.

Mitochondrial Damage-Associated Molecular Patterns and Metabolism in the Regulation of Innate Immunity

The innate immune system, as the host's first line of defense against intruders, plays a critical role in recognizing, identifying, and reacting to a wide range of microbial intruders. There is increasing evidence that mitochondrial stress is a major initiator of innate immune responses. When mitochondria's integrity is disrupted or dysfunction occurs, the mitochondria's contents are released into the cytosol. These contents, like reactive oxygen species, mitochondrial DNA, and double-stranded RNA, among others, act as damage-related molecular patterns (DAMPs) that can bind to multiple innate immune sensors, particularly pattern recognition receptors, thereby leading to inflammation. To avoid the production of DAMPs, in addition to safeguarding organelles integrity and functionality, mitochondria may activate mitophagy or apoptosis. Moreover, mitochondrial components and specific metabolic regulations modify properties of innate immune cells. These include macrophages, dendritic cells, innate lymphoid cells, and so on, in steady state or in stimulation that are involved in processes ranging from the tricarboxylic acid cycle to oxidative phosphorylation and fatty acid metabolism. Here we provide a brief summary of mitochondrial DAMPs' initiated and potentiated inflammatory response in the innate immune system. We also provide insights into how the state of activation, differentiation, and functional polarization of innate immune cells can be influenced by alteration to the metabolic pathways in mitochondria.

Inetetamab, a novel anti-HER2 monoclonal antibody, exhibits potent synergistic anticancer effects with cisplatin by inducing pyroptosis in lung adenocarcinoma

Cisplatin is a first-line chemotherapy drug for lung adenocarcinoma (LUAD). However, its therapeutic efficacy is limited because of serious side effects and acquired drug resistance. Targeting HER2 has been proven to be a viable therapeutic strategy against LUAD. Moreover, inetetamab, an innovative anti-HER2 monoclonal antibody, has a more potent antibody-dependent cell-mediated cytotoxicity (ADCC)-inducing effect than trastuzumab, which has been shown to be an effective and rational strategy in the clinic when combined with multiple chemotherapeutic agents. Thus, the present study aimed to explore the synergistic effects of cisplatin (DDP) and inetetamab in LUAD cells and investigate the detailed underlying mechanisms. Here, in vitro and in vivo, we found that the combination of inetetamab and cisplatin induced synergistic effects, including induction of pyroptosis, in LUAD. Mechanistic studies revealed that inetetamab combined with cisplatin inhibited HER2/AKT/Nrf2 signaling to increase ROS levels, which triggered NLRP3/caspase-1/GSDMB-mediated pyroptosis to synergistically enhance antitumor efficacy in LUAD cells. In addition, cisplatin enhanced the PBMC-killing ability of inetetamab by inducing GSDMB-mediated pyroptosis, which can be explained by increased secretion of IFN-γ. Our study reveals that the anti-HER2 monoclonal antibody inetetamab may be an attractive candidate for LUAD therapy, which opens new avenues for therapeutic interventions for LUAD.

Damage-mediated macrophage polarization in sterile inflammation

Most of the leading causes of death, such as cardiovascular diseases, cancer, dementia, neurodegenerative diseases, and many more, are associated with sterile inflammation, either as a cause or a consequence of these conditions. The ability to control the progression of inflammation toward tissue resolution before it becomes chronic holds significant clinical potential. During sterile inflammation, the initiation of inflammation occurs through damage-associated molecular patterns (DAMPs) in the absence of pathogen-associated molecules. Macrophages, which are primarily localized in the tissue, play a pivotal role in sensing DAMPs. Furthermore, macrophages can also detect and respond to resolution-associated molecular patterns (RAMPs) and specific pro-resolving mediators (SPMs) during sterile inflammation. Macrophages, being highly adaptable cells, are particularly influenced by changes in the microenvironment. In response to the tissue environment, monocytes, pro-inflammatory macrophages, and pro-resolution macrophages can modulate their differentiation state. Ultimately, DAMP and RAMP-primed macrophages, depending on the predominant subpopulation, regulate the balance between inflammatory and resolving processes. While sterile injury and pathogen-induced reactions may have distinct effects on macrophages, most studies have focused on macrophage responses induced by pathogens. In this review, which emphasizes available human data, we illustrate how macrophages sense these mediators by examining the expression of receptors for DAMPs, RAMPs, and SPMs. We also delve into the signaling pathways induced by DAMPs, RAMPs, and SPMs, which primarily contribute to the regulation of macrophage differentiation from a pro-inflammatory to a pro-resolution phenotype. Understanding the regulatory mechanisms behind the transition between macrophage subtypes can offer insights into manipulating the transition from inflammation to resolution in sterile inflammatory diseases.

Regulatory Functions of Hypoxia in Host-Parasite Interactions: A Focus on Enteric, Tissue, and Blood Protozoa

Body tissues are subjected to various oxygenic gradients and fluctuations and hence can become transiently hypoxic. Hypoxia-inducible factor (HIF) is the master transcriptional regulator of the cellular hypoxic response and is capable of modulating cellular metabolism, immune responses, epithelial barrier integrity, and local microbiota. Recent reports have characterized the hypoxic response to various infections. However, little is known about the role of HIF activation in the context of protozoan parasitic infections. Growing evidence suggests that tissue and blood protozoa can activate HIF and subsequent HIF target genes in the host, helping or hindering their pathogenicity. In the gut, enteric protozoa are adapted to steep longitudinal and radial oxygen gradients to complete their life cycle, yet the role of HIF during these protozoan infections remains unclear. This review focuses on the hypoxic response to protozoa and its role in the pathophysiology of parasitic infections. We also discuss how hypoxia modulates host immune responses in the context of protozoan infections.

Echinacea purpurea-derived homogeneous polysaccharide exerts anti-tumor efficacy via facilitating M1 macrophage polarization

Echinacea purpurea modulates tumor progression, but the underlying mechanism is poorly defined. We isolated and purified a novel homogeneous polysaccharide from E. purpurea (EPPA), which was shown to be an arabinogalactan with a mean molecular mass (Mr) of 3.8 × 10⁴ Da and with α- (1 → 5) -L-Arabinan as the backbone and α-L-Araf-(1→, →6)-β-D-Galp-(1→, and →4)-α-D-GalpA-(1→ as the side chains. Interestingly, oral administration of EPPA suppresses tumor progression in vivo and shapes the immune cell profile (e.g., facilitating M1 macrophages) in tumor microenvironment by single-cell RNA sequencing (scRNA-seq) analysis. More importantly, EPPA activates the inflammasome through a phagocytosis-dependent mechanism and rewires transcriptomic and metabolic profile, thereby potentiating M1 macrophage polarization. Collectively, we propose that EPPA supplementation could function as an adjuvant therapeutic strategy for tumor suppression.

Fine particulate matter (PM2.5) induces inhibitory memory alveolar macrophages through the AhR/IL-33 pathway

Fine particulate matter (PM2.5) concentrations have decreased in the past decade. The adverse effects of acute PM2.5 exposure on respiratory diseases have been well recognized. To explore the long-term effects of PM2.5 exposure on chronic obstructive pulmonary disease (COPD), mice were exposed to PM2.5 for 7 days and rest for 21 days, followed by challenges with lipopolysaccharide (LPS) and porcine pancreatic elastase (PPE). Unexpectedly, PM2.5 exposure and rest alleviated the disease severity and airway inflammatory responses in COPD-like mice. Although acute PM2.5 exposure increased airway inflammation, rest for 21 days reversed the airway inflammatory responses, which was associated with the induction of inhibitory memory alveolar macrophages (AMs). Similarly, polycyclic aromatic hydrocarbons (PAHs) in PM2.5 exposure and rest decreased pulmonary inflammation, accompanied by inhibitory memory AMs. Once AMs were depleted, pulmonary inflammation was aggravated. PAHs in PM2.5 promoted the secretion of IL-33 from airway epithelial cells via the aryl hydrocarbon receptor (AhR)/ARNT pathway. High-throughput mRNA sequencing revealed that PM2.5 exposure and rest drastically changed the mRNA profiles in AMs, which was largely rescued in IL-33^-/- mice. Collectively, our results indicate that PM2.5 may mitigate pulmonary inflammation, which is mediated by inhibitory trained AMs via IL-33 production from epithelial cells through the AhR/ARNT pathway. We provide the rationale that PM2.5 plays complicated roles in respiratory disease.

Endogenous IL-33 Accelerates Metacestode Growth during Late-Stage Alveolar Echinococcosis

During the course of the infectious disease alveolar echinococcosis (AE), the larval stage of Echinococcus multilocularis develops in the liver, where an initial Th1/Th17 immune response may allow its elimination in resistant individuals. In patients susceptible to infection and disease, the Th2 response initiates later, inducing tolerance to the parasite. The role of interleukin 33 (IL-33), an alarmin released during necrosis and known to drive a Th2 immune response, has not yet been described during AE. Wild-type (WT) and IL-33-/- C57BL/6J mice were infected by peritoneal inoculation with E. multilocularis metacestodes and euthanized 4 months later, and their immune response were analyzed. Immunofluorescence staining and IL-33 enzyme-linked immunosorbent assay (ELISA) were also performed on liver samples from human patients with AE. Overall, metacestode lesions were smaller in IL-33-/- mice than in WT mice. IL-33 was detected in periparasitic tissues, but not in mouse or human serum. In infected mice, endogenous IL-33 modified peritoneal macrophage polarization and cytokine profiles. Th2 cytokine concentrations were positively correlated with parasite mass in WT mice, but not in IL-33-/- mice. In human AE patients, IL-33 concentrations were higher in parasitic tissues than in distant liver parenchyma. The main sources of IL-33 were CD31+ endothelial cells of the neovasculature, present within lymphoid periparasitic infiltrates together with FOXP3+ Tregs. In the murine model, periparasitic IL-33 correlated with accelerated parasite growth putatively through the polarization of M2-like macrophages and release of immunosuppressive cytokines IL-10 and transforming growth factor β1 (TGF-β1). We concluded that IL-33 is a key alarmin in AE that contributes to the tolerogenic effect of systemic Th2 cytokines. IMPORTANCE Infection with the metacestode stage of Echinococcus multilocularis, known as alveolar echinococcosis, is the most severe cestodosis worldwide. However, less than 1% of exposed individuals, in which the immune system is unable to control the parasite, develop the disease. The factors responsible for this interindividual variability are not fully understood. In this in vivo study comparing wild-type and IL-33-/- infected mice, together with data from human clinical samples, we determined that IL-33, an alarmin released following tissue injury and involved in the pathogenesis of cancer and asthma, accelerates the progression of the disease by modulating the periparasitic microenvironment. This suggests that targeting IL-33 could be of interest for the management of patients with AE, and that IL-33 polymorphisms could be responsible for increased susceptibility to AE.

Natural products targeting macrophages in tumor microenvironment are a source of potential antitumor agents

BACKGROUND

Macrophages are one of the major cell types in the immune system and are closely related to tumor development, which can be polarized into M1 type with anti-tumor activity or M2 type with pro-tumor activity. The infiltration of more macrophages into tumor predicts poorer prognosis due to their more exhibition of M2 phenotype under the influence of many factors in the tumor microenvironment (TME). Therefore, reverse of M2 macrophage polarization in TME is conducive to the suppression of tumor deterioration and understanding the influencing factors of macrophage polarization is helpful to provide new ideas for the subsequent targeting macrophages for tumor therapy.

PURPOSE

This review summarizes the effects of TME on macrophage polarization and natural products against M2 macrophage polarization, which may provide some directions for tumor therapy.

METHODS

The search of relevant literature was conducted using the PubMed, Science Direct, CNKI and Web of Science databases with the search terms "macrophage", "tumor microenvironment", "natural product" and "tumor".

RESULTS

The mutual transformation of M1 and M2 phenotypes in macrophages is influenced by many factors. Tumor cells affect the polarization of macrophages by regulating the expression of genes and proteins and the secretion of cytokines. The expression of some genes or proteins in macrophages is also related to their own polarization. Many natural products can reverse M2 polarization of macrophages which has been summarized in this review.

CONCLUSION

Regulation of macrophage polarization in TME can inhibit tumor development, and natural products have the potential to impede tumor development by regulating macrophage polarization.

Dual Immune Regulatory Roles of Interleukin-33 in Pathological Conditions

Interleukin-33 (IL-33), a member of the IL-1 cytokine family and a multifunctional cytokine, plays critical roles in maintaining host homeostasis and in pathological conditions, such as allergy, infectious diseases, and cancer, by acting on multiple types of immune cells and promoting type 1 and 2 immune responses. IL-33 is rapidly released by immune and non-immune cells upon stimulation by stress, acting as an “alarmin” by binding to its receptor, suppression of tumorigenicity 2 (ST2), to trigger downstream signaling pathways and activate inflammatory and immune responses. It has been recognized that IL-33 displays dual-functioning immune regulatory effects in many diseases and has both pro- and anti-tumorigenic effects, likely depending on its primary target cells, IL-33/sST2 expression levels, cellular context, and the cytokine microenvironment. Herein, we summarize our current understanding of the biological functions of IL-33 and its roles in the pathogenesis of various conditions, including inflammatory and autoimmune diseases, infections, cancers, and cases of organ transplantation. We emphasize the nature of context-dependent dual immune regulatory functions of IL-33 in many cells and diseases and review systemic studies to understand the distinct roles of IL-33 in different cells, which is essential to the development of more effective diagnoses and therapeutic approaches for IL-33-related diseases.

Blockade of exosome generation by GW4869 inhibits the education of M2 macrophages in prostate cancer

Background

Tumor-associated macrophages are considered to be a major contributor affecting the development of tumors. Recently, numerous studies have shown that tumor cells were able to educate their microenvironment by delivering a significant amount of exosomes, however, the mechanism that exosomes from PCa cells work in macrophage polarization remains obscure. Therefore, we sought to determine whether blockade of exosome generation by GW4869, an inhibitor of exosome biogenesis, would impede macrophages from differentiating into M2 cells.

Results

In this study, we first obtained exosomes from the supernatant media of PCa cells cultured with exosome-free serum using the Magcapture™ Exosome Isolation Kit PS, and then investigated their effects on macrophages. Our data confirmed that exosomes released by prostate cancer cells can induce macrophages to differentiate into M2 cells. Mechanistically speaking, exosomes exert their effects on macrophages through activating the AKT and STAT3 signaling pathways. Importantly, treatment with GW4869 significantly inhibited the release of exosomes from PCa cells, and further impaired M2 differentiation of macrophages and their pro-tumor activity. We also demonstrated that GW4869 was able to inhibit the education of M2 macrophages, and then inhibit the progression of prostate cancer in vivo.

Conclusions

In brief, our findings indicated that GW4869 impeded the PCa exosome-induced M2 differentiation of macrophages and the progression of prostate cancer, suggesting that GW4869 could play an important role in the treatment of prostate cancer metastasis as an inhibitor of tumor exosome secretion.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00514-3.

Interleukin-33: Metabolic checkpoints, metabolic processes, and epigenetic regulation in immune cells

Interleukin-33 (IL-33) is a pleiotropic cytokine linked to various immune cells in the innate and adaptive immune systems. Recent studies of the effects of IL-33 on immune cells are beginning to reveal its regulatory mechanisms at the levels of cellular metabolism and epigenetic modifications. In response to IL-33 stimulation, these programs are intertwined with transcriptional programs, ultimately determining the fate of immune cells. Understanding these specific molecular events will help to explain the complex role of IL-33 in immune cells, thereby guiding the development of new strategies for immune intervention. Here, we highlight recent findings that reveal how IL-33, acting as an intracellular nuclear factor or an extracellular cytokine, alters metabolic checkpoints and cellular metabolism, which coordinately contribute to cell growth and function. We also discuss recent studies supporting the role of IL-33 in epigenetic alterations and speculate about the mechanisms underlying this relationship.

Roles for macrophage-polarizing interleukins in cancer immunity and immunotherapy

Macrophages are the most abundant and one of the most critical cells of tumor immunity. They provide a bridge between innate and adaptive immunity through releasing cytokines into the tumor microenvironment (TME). A number of interleukin (IL) cytokine family members is involved in shaping the final phenotype of macrophages toward either a classically-activated pro-inflammatory M1 state with anti-tumor activity or an alternatively-activated anti-inflammatory M2 state with pro-tumor activity. Shaping TME macrophages toward the M1 phenotype or recovering this phenotypic state may offer a promising therapeutic approach in patients with cancer. Here, we focus on the impact of macrophage-polarizing ILs on immune cells and IL-mediated cellular cross-interactions within the TME. The key aim of this review is to define therapeutic schedules for addressing ILs in cancer immunotherapy based on their multi-directional impacts in such a milieu. Gathering more knowledge on this area is also important for defining adverse effects related to cytokine therapy and addressing them for reinforcing the efficacy of immunotherapy against cancer.

Suppression of Aspergillus fumigatus Germination by Neutrophils Is Enhanced by Endothelial-Derived CSF3 Production

Infection with Aspergillus fumigatus can cause life-threatening diseases in immunocompromised patients with an unacceptable mortality rate. Angioinvasion is one of the features of severe invasive aspergillosis. Neutrophils are short-lived immune cells regulated by colony-stimulating factor 3 (CSF3) that play a key role in anti-fungal immune responses. To investigate the interactions between A. fumigatus and the host immune cells, such as neutrophils, we stimulated human umbilical vein endothelial cells (HUVECs) with the conidia of A. fumigatus, and co-cultured them with human neutrophils. Apoptosis and functions of neutrophils were analyzed. Our results showed that HUVECs upregulate the expression of CSF3, which could reduce the apoptosis of neutrophils while enhancing their functions. Lack of CSF3 was associated with enhanced apoptosis of neutrophils with impaired function. This work indicated that the CSF3 is required for neutrophil survival and function, at least in the early stages of A. fumigatus infection.

An imbalance of the IL-33/ST2-AXL-efferocytosis axis induces pregnancy loss through metabolic reprogramming of decidual macrophages

During embryo implantation, apoptosis is inevitable. These apoptotic cells (ACs) are removed by efferocytosis, in which macrophages are filled with a metabolite load nearly equal to the phagocyte itself. A timely question pertains to the relationship between efferocytosis-related metabolism and the immune behavior of decidual macrophages (dMΦs) and its effect on pregnancy outcome. Here, we report positive feedback of IL-33/ST2-AXL-efferocytosis leading to pregnancy failure through metabolic reprogramming of dMΦs. We compared the serum levels of IL-33 and sST2, along with IL-33 and ST2, efferocytosis and metabolism of dMΦs, from patients with normal pregnancies and unexplained recurrent pregnancy loss (RPL). We revealed disruption of the IL-33/ST2 axis, increased apoptotic cells and elevated efferocytosis of dMΦs from patients with RPL. The dMΦs that engulfed many apoptotic cells secreted more sST2 and less TGF-β, which polarized dMΦs toward the M1 phenotype. Moreover, the elevated sST2 biased the efferocytosis-related metabolism of RPL dMΦs toward oxidative phosphorylation and exacerbated the disruption of the IL-33/ST2 signaling pathway. Metabolic disorders also lead to dysfunction of efferocytosis, resulting in more uncleared apoptotic cells and secondary necrosis. We also screened the efferocytotic molecule AXL regulated by IL-33/ST2. This positive feedback axis of IL-33/ST2-AXL-efferocytosis led to pregnancy failure. IL-33 knockout mice demonstrated poor pregnancy outcomes, and exogenous supplementation with mouse IL-33 reduced the embryo losses. These findings highlight a new etiological mechanism whereby dMΦs leverage immunometabolism for homeostasis of the microenvironment at the maternal-fetal interface.

ROS-Induced mtDNA Release: The Emerging Messenger for Communication between Neurons and Innate Immune Cells during Neurodegenerative Disorder Progression

One of the most striking hallmarks shared by various neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease and amyotrophic lateral sclerosis, is microglia-mediated and astrocyte-mediated neuroinflammation. Although inhibitions of both harmful proteins and aggregation are major treatments for neurodegenerative diseases, whether the phenomenon of non-normal protein or peptide aggregation is causally related to neuronal loss and synaptic damage is still controversial. Currently, excessive production of reactive oxygen species (ROS), which induces mitochondrial dysfunction in neurons that may play a key role in the regulation of immune cells, is proposed as a regulator in neurological disorders. In this review, we propose that mitochondrial DNA (mtDNA) release due to ROS may act on microglia and astrocytes adjacent to neurons to induce inflammation through activation of innate immune responses (such as cGAS/STING). Elucidating the relationship between mtDNA and the formation of a pro-inflammatory microenvironment could contribute to a better understanding of the mechanism of crosstalk between neuronal and peripheral immune cells and lead to the development of novel therapeutic approaches to neurodegenerative diseases.