STAT3 and STAT6 Signaling Pathways Synergize to Promote Cathepsin Secretion from Macrophages via IRE1α Activation

Macrophages and tumor-associated macrophages in the senescent microenvironment: From immunosuppressive TME to targeted tumor therapy

In-depth studies of the tumor microenvironment (TME) have helped to elucidate its cancer-promoting mechanisms and inherent characteristics. Cellular senescence, which acts as a response to injury and can the release of senescence-associated secretory phenotypes (SASPs). These SASPs release various cytokines, chemokines, and growth factors, remodeling the TME. This continual development of a senescent environment could be associated with chronic inflammation and immunosuppressive TME. Additionally, SASPs could influence the phenotype and function of macrophages, leading to the recruitment of tumor-associated macrophages (TAMs). This contributes to tumor proliferation and metastasis in the senescent microenvironment, working in tandem with immune regulation, angiogenesis, and therapeutic resistance. This comprehensive review covers the evolving nature of the senescent microenvironment, macrophages, and TAMs in tumor development. We also explored the links between chronic inflammation, immunosuppressive TME, cellular senescence, and macrophages. Moreover, we compiled various tumor-specific treatment strategies centered on cellular senescence and the current challenges in cellular senescence research. This study aimed to clarify the mechanism of macrophages and the senescent microenvironment in tumor progression and advance the development of targeted tumor therapies.

Glucose-driven histone lactylation promotes the immunosuppressive activity of monocyte-derived macrophages in glioblastoma

Immunosuppressive macrophages restrict anti-cancer immunity in glioblastoma (GBM). Here, we studied the contribution of microglia (MGs) and monocyte-derived macrophages (MDMs) to immunosuppression and mechanisms underlying their regulatory function. MDMs outnumbered MGs at late tumor stages and suppressed T cell activity. Molecular and functional analysis identified a population of glycolytic MDM expressing GLUT1 with potent immunosuppressive activity. GBM-derived factors promoted high glycolysis, lactate, and interleukin-10 (IL-10) production in MDMs. Inhibition of glycolysis or lactate production in MDMs impaired IL-10 expression and T cell suppression. Mechanistically, intracellular lactate-driven histone lactylation promoted IL-10 expression, which was required to suppress T cell activity. GLUT1 expression on MDMs was induced downstream of tumor-derived factors that activated the PERK-ATF4 axis. PERK deletion in MDM abrogated histone lactylation, led to the accumulation of intratumoral T cells and tumor growth delay, and, in combination with immunotherapy, blocked GBM progression. Thus, PERK-driven glucose metabolism promotes MDM immunosuppressive activity via histone lactylation.

Reprogramming Tumor-Associated Macrophage Using Nanocarriers: New Perspectives to Halt Cancer Progression

Cancer remains a significant challenge for public healthcare systems worldwide. Within the realm of cancer treatment, considerable attention is focused on understanding the tumor microenvironment (TME)-the complex network of non-cancerous elements surrounding the tumor. Among the cells in TME, tumor-associated macrophages (TAMs) play a central role, traditionally categorized as pro-inflammatory M1 macrophages or anti-inflammatory M2 macrophages. Within the TME, M2-like TAMs can create a protective environment conducive to tumor growth and progression. These TAMs secrete a range of factors and molecules that facilitate tumor angiogenesis, increased vascular permeability, chemoresistance, and metastasis. In response to this challenge, efforts are underway to develop adjuvant therapy options aimed at reprogramming TAMs from the M2 to the anti-tumor M1 phenotype. Such reprogramming holds promise for suppressing tumor growth, alleviating chemoresistance, and impeding metastasis. Nanotechnology has enabled the development of nanoformulations that may soon offer healthcare providers the tools to achieve targeted drug delivery, controlled drug release within the TME for TAM reprogramming and reduce drug-related adverse events. In this review, we have synthesized the latest data on TAM polarization in response to TME factors, highlighted the pathological effects of TAMs, and provided insights into existing nanotechnologies aimed at TAM reprogramming and depletion.

Elevated Circulating Procathepsin L as a Potential Biomarker of Inflamm-aging

Inflamm-aging is a condition of low-grade and chronic systemic inflammation characterized by a systemic increase in multiple inflammatory biomarkers such as tumor necrosis factor (TNF), interleukin 6 (IL-6), C-reactive protein (CRP), and CXCL9 (MIG) in experimental and clinical settings. However, despite the recent identification of extracellular procathepsin L (pCTS-L) as a novel mediator of inflammatory diseases such as sepsis, its possible role in inflamm-aging was previously not investigated. In the present study, we compared blood levels of pCTS-L and other 62 cytokines and chemokines between young and aged Balb/C mice by Western blotting and Cytokine Antibody Arrays. In light of the surprising finding of a marked increase in blood pCTS-L levels in aged mice, we propose that blood pCTS-L levels may serve as another biomarker of inflamm-aging. Given the capacity of pCTS-L in inducing various cytokines (e.g., TNF and IL-6), it will be important to test the hypothetic role of pCTS-L in inflamm-aging under experimental and clinical conditions.

Myeloid-derived suppressor cells in cancer: therapeutic targets to overcome tumor immune evasion

Paradoxically, tumor development and progression can be inhibited and promoted by the immune system. After three stages of immune editing, namely, elimination, homeostasis and escape, tumor cells are no longer restricted by immune surveillance and thus develop into clinical tumors. The mechanisms of immune escape include abnormalities in antitumor-associated immune cells, selection for immune resistance to tumor cells, impaired transport of T cells, and the formation of an immunosuppressive tumor microenvironment. A population of distinct immature myeloid cells, myeloid-derived suppressor cells (MDSCs), mediate immune escape primarily by exerting immunosuppressive effects and participating in the constitution of an immunosuppressive microtumor environment. Clinical trials have found that the levels of MDSCs in the peripheral blood of cancer patients are strongly correlated with tumor stage, metastasis and prognosis. Moreover, animal experiments have confirmed that elimination of MDSCs inhibits tumor growth and metastasis to some extent. Therefore, MDSCs may become the target of immunotherapy for many cancers, and eliminating MDSCs can help improve the response rate to cancer treatment and patient survival. However, a clear definition of MDSCs and the specific mechanism involved in immune escape are lacking. In this paper, we review the role of the MDSCs population in tumor development and the mechanisms involved in immune escape in different tumor contexts. In addition, we discuss the use of these cells as targets for tumor immunotherapy. This review not only contributes to a systematic and comprehensive understanding of the essential role of MDSCs in immune system reactions against tumors but also provides information to guide the development of cancer therapies targeting MDSCs.

Insights into the complex interactions between Rab22a and extracellular vesicles in cancers

INTRODUCTION

Oncogenic Ras-related GTP-binding proteins, referred to as Rabs, are characterized by their intricate interactions with upstream, downstream molecules, and notably, extracellular vesicles (EVs). While the expansive family of Rabs and their associated signaling pathways have been exhaustively dissected, Rab22a emerges as an entity of outstanding interest, owing to its potent influence in many biological processes and its conspicuous correlation with cancer metastasis and migration. A burgeoning interest in the interactions between Rab22a and EVs in the field of oncology underscores the necessity for more in-depth reviews and scholarly discourses.

METHODS

We performed a review based on published original and review articles related to Rab22a, tumor, microRNA, exosome, microvesicles, EVs, CD147, lysosome, degradation, endosomal recycling, etc. from PubMed, Web of Science and Google Scholar databases.

RESULTS AND CONCLUSIONS

We summarize the regulatory processes governing the expression of Rab22a and the mutants of Rab22a. Notably, the present understanding of complex interactions between Rab22a and EVs are highlighted, encompassing both the impact of Rab22a on the genesis of EVs and the role of EVs that are affected by Rab22a mutants in propelling tumor advancement. The dynamic interaction between Rab22a and EVs plays a significant role in the progression of tumors, and it can provide novel insights into the pathogenesis of cancers and the development of new therapeutic targets.

O-GlcNAcylation at the center of antitumor immunity

The post-translational modification known as O-GlcNAcylation is a highly dysregulated process in tumors, and a key contributor to malignant transformation. In contrast, after three decades since its discovery, very little has been revealed about this process in the immune system. With the prospect of targeting O-GlcNAcylation as tumor therapy, greater understanding of how it regulates immune responses in the context of the tumor microenvironment will be needed. Here, we discuss recent discoveries from which a picture is emerging that O-GlcNAcylation, in either tumors or in immune cells, could negatively impact overall antitumor immune responses. We propose that interference with O-GlcNAcylation thus holds promise for cancer treatment from both perspectives.

Characterization of endoplasmic reticulum stress unveils ZNF703 as a promising target for colorectal cancer immunotherapy

BACKGROUND

Colorectal cancer (CRC) is one of the most common malignant tumors globally, with high morbidity and mortality. Endoplasmic reticulum is a major organelle responsible for protein synthesis, processing, and transport. Endoplasmic reticulum stress (ERS) refers to the abnormal accumulation of unfolded and misfolded proteins in the endoplasmic reticulum, which are involved in tumorigenesis and cancer immunity. Nevertheless, the clinical significance of ERS remains largely unexplored in CRC.

METHODS

In present study, we performed an unsupervised clustering to identify two types of ERS-related subtypes [ERS clusters, and ERS-related genes (ERSGs) clusters] in multiple large-scale CRC cohorts. Through the utilization of machine learning techniques, we have successfully developed an uncomplicated yet robust gene scoring system (ERSGs signature). Furthermore, a series of analyses, including GO, KEGG, Tumor Immune Dysfunction and Exclusion (TIDE), the Consensus Molecular Subtypes (CMS), were used to explore the underlying biological differences and clinical significance between these groups. And immunohistochemical and bioinformatics analyses were performed to explore ZNF703, a gene of ERSGs scoring system.

RESULTS

We observed significant differences in prognosis and tumor immune status between the ERS clusters as well as ERSGs clusters. And the ERSGs scoring system was an independent risk factor for overall survival; and exhibited distinct tumor immune status in multicenter CRC cohorts. Besides, analyses of TNM stages, CMS groups demonstrated that patients in advanced stage and CMS4 had higher ERSGs scores. In addition, the ERSGs scores inversely correlated with positive ICB response predictors (such as, CD8A, CD274 (PD-L1), and TIS), and directly correlated with negative ICB response predictors (such as, TIDE, T cell Exclusion, COX-IS). Notably, immunohistochemical staining and bioinformatics analyses revealed that ZNF70 correlated with CD3 + and CD8 + T cells infiltration.

CONCLUSION

Based on large-scale and multicenter transcriptomic data, our study comprehensively revealed the essential role of ERS in CRC; and constructed a novel ERSGs scoring system to predict the prognosis of patients and the efficacy of ICB treatment. Furthermore, we identified ZNF703 as a potentially promising target for ICB therapy in CRC.

Piezo1 specific deletion in macrophage protects the progression of liver fibrosis in mice

Background and Aims: Liver fibrosis is the common pathological pathway of chronic liver diseases and its mechanisms of which have not been fully declared. Macrophages play essential roles in progression of liver fibrosis partially by sensing abnormal mechanical signals. The aim of the study is to investigate the functions of macrophage Piezo1, a mechano-sensitive ion channel, in liver fibrosis. Approach and Results: Immunofluorescence in human and murine fibrotic liver samples revealed that expression of macrophage Piezo1 was increased. Myeloid-specific Piezo1 knockout (Piezo1ΔLysM) attenuated liver fibrosis by decreased collagen deposition and epithelial-mesenchymal transition (EMT). In Piezo1ΔLysM mice, less inflammation during development of liver fibrosis was observed by lessened macrophage infiltration, decreased M1 polarization and expression of inflammatory cytokines. RNA-seq data showed macrophage Piezo1 regulated transcription of cathepsin S (CTSS). Piezo1ΔLysM inhibited expression and activity of CTSS in vitro and in vivo and regulated T cell activity. Furthermore, inhibition of CTSS reversed macrophage inflammatory response driven by Piezo1 activation and LPS. Macrophage Piezo1 activation promoted CTSS secretion due to increased activity of Ca2+-dependent calpain protease induced by Ca2+ influx to cleave lysosome-associated membrane protein-1 (LAMP1). Pharmacological inhibition of calpain activity partially blocked Piezo1 mediated CTSS secretion. Conclusions: Macrophage Piezo1 deficiency limits the progression of liver fibrosis by inhibited inflammatory response and decreased secretion of CTSS. These findings suggest that targeting Piezo1 channel may be a potential strategy for treating hepatic fibrosis.

Crosstalk between endoplasmic reticulum stress and multidrug-resistant cancers: hope or frustration

Endoplasmic reticulum stress (ERS) is a kind of cell response for coping with hypoxia and other stresses. Pieces of evidence show that continuous stress can promote the occurrence, development, and drug resistance of tumors through the unfolded protein response. Therefore, the abnormal ac-tivation of ERS and its downstream signaling pathways not only can regulate tumor growth and metastasis but also profoundly affect the efficacy of antitumor therapy. Therefore, revealing the molecular mechanism of ERS may be expected to solve the problem of tumor multidrug resistance (MDR) and become a novel strategy for the treatment of refractory and recurrent tumors. This re-view summarized the mechanism of ERS and tumor MDR, reviewed the relationship between ERS and tumor MDR, introduced the research status of tumor tissue and ERS, and previewed the prospect of targeting ERS to improve the therapeutic effect of tumor MDR. This article aims to provide researchers and clinicians with new ideas and inspiration for basic antitumor treatment.

Control of immune cell function by the unfolded protein response

Initiating and maintaining optimal immune responses requires high levels of protein synthesis, folding, modification and trafficking in leukocytes, which are processes orchestrated by the endoplasmic reticulum. Importantly, diverse extracellular and intracellular conditions can compromise the protein-handling capacity of this organelle, inducing a state of 'endoplasmic reticulum stress' that activates the unfolded protein response (UPR). Emerging evidence shows that physiological or pathological activation of the UPR can have effects on immune cell survival, metabolism, function and fate. In this Review, we discuss the canonical role of the adaptive UPR in immune cells and how dysregulation of this pathway in leukocytes contributes to diverse pathologies such as cancer, autoimmunity and metabolic disorders. Furthermore, we provide an overview as to how pharmacological approaches that modulate the UPR could be harnessed to control or activate immune cell function in disease.

Regulation of intrinsic and extrinsic metabolic pathways in tumour-associated macrophages

Tumour-associated macrophages (TAMs) are highly plastic and are broadly grouped into two major functional states, namely the pro-inflammatory M1-type and the pro-tumoural M2-type. Conversion of the functional states of TAMs is regulated by various cytokines, chemokines growth factors and other secreted factors in the microenvironment. Dysregulated metabolism is a hallmark of cancer. Emerging evidence suggests that metabolism governs the TAM differentiation and functional conversation in support of tumour growth and metastasis. Aside from the altered metabolism reprogramming in TAMs, extracellular metabolites secreted by cancer, stromal and/or other cells within the tumour microenvironment have been found to regulate TAMs through passive competition for metabolite availability and direct regulation via receptor/transporter-mediated signalling reaction. In this review, we focus on the regulatory roles of different metabolites and metabolic pathways in TAM conversion and function. We also discuss if the dysregulated metabolism in TAMs can be exploited for the development of new therapeutic strategies against cancer.

Role of Fibroblasts in Chronic Inflammatory Signalling in Chronic Rhinosinusitis with Nasal Polyps-A Systematic Review

Chronic rhinosinusitis with nasal polyps (CRSwNP) is an inflammatory disease of the nose and paranasal sinuses characterized by the presence of nasal polyps. The symptoms produced by the presence of nasal polyps such as nasal obstruction, nasal discharge, facial pain, headache, and loss of smell cause a worsening in the quality of life of patients. The source of the nasal polyps remains unclear, although it seems to be due to a chronic inflammation process in the sinonasal mucosa. Fibroblasts, the main cells in connective tissue, are intimately involved in the inflammation processes of various diseases; to this end, we carried out a systematic review to evaluate their inflammatory role in nasal polyps. Thus, we evaluated the main cytokines produced by nasal polyp-derived fibroblasts (NPDF) to assess their involvement in the production of nasal polyps and their involvement in different inflammatory pathways. The results of the review highlight the inflammatory role of NPDF through the secretion of various cytokines involved in the T1, T2, and T3 inflammatory pathways, as well as the ability of NPDF to be stimulated by a multitude of substances. With these findings, the fibroblast is positioned as a new potential therapeutic target in the treatment of CRSwNP.

Tumor-associated macrophages: Prognostic and therapeutic targets for cancer in humans and dogs

Macrophages are ancient, phagocytic immune cells thought to have their origins 500 million years ago in metazoan phylogeny. The understanding of macrophages has evolved to encompass their foundational roles in development, homeostasis, tissue repair, inflammation, and immunity. Notably, macrophages display high plasticity in response to environmental cues, capable of a strikingly wide variety of dynamic gene signatures and phenotypes. Macrophages are also involved in many pathological states including neural disease, asthma, liver disease, heart disease, cancer, and others. In cancer, most tumor-associated immune cells are macrophages, coined tumor-associated macrophages (TAMs). While some TAMs can display anti-tumor properties such as phagocytizing tumor cells and orchestrating an immune response, most macrophages in the tumor microenvironment are immunosuppressive and pro-tumorigenic. Macrophages have been implicated in all stages of cancer. Therefore, interest in manipulating macrophages as a therapeutic strategy against cancer developed as early as the 1970s. Companion dogs are a strong comparative immuno-oncology model for people due to documented similarities in the immune system and spontaneous cancers between the species. Data from clinical trials in humans and dogs can be leveraged to further scientific advancements that benefit both species. This review aims to provide a summary of the current state of knowledge on macrophages in general, and an in-depth review of macrophages as a therapeutic strategy against cancer in humans and companion dogs.

How the Unfolded Protein Response Is a Boon for Tumors and a Bane for the Immune System

The correct folding of proteins is essential for appropriate cell function and is tightly regulated within the endoplasmic reticulum (ER). Environmental challenges and cellular conditions disrupt ER homeostasis and induce ER stress, which adversely affect protein folding and activate the unfolded protein response (UPR). It is now becoming recognized that cancer cells can overcome survival challenges posed within the tumor microenvironment by activating the UPR. Furthermore, the UPR has also been found to impose detrimental effects on immune cells by inducing immunoinhibitory activity in both tumor-infiltrating innate and adaptive immune cells. This suggests that these signaling axes may be important therapeutic targets, resulting in multifaceted approaches to eradicating tumor cells. In this mini-review, we discuss the role of the UPR in driving tumor progression and modulating the immune system's ability to target cancer cells. Additionally, we highlight some of the key unanswered questions that may steer future UPR research.

The IRE1α-XBP1 Signaling Axis Promotes Glycolytic Reprogramming in Response to Inflammatory Stimuli

Immune cells must be able to adjust their metabolic programs to effectively carry out their effector functions. Here, we show that the endoplasmic reticulum (ER) stress sensor Inositol-requiring enzyme 1 alpha (IRE1α) and its downstream transcription factor X box binding protein 1 (XBP1) enhance the upregulation of glycolysis in classically activated macrophages (CAMs). The IRE1α-XBP1 signaling axis supports this glycolytic switch in macrophages when activated by lipopolysaccharide (LPS) stimulation or infection with the intracellular bacterial pathogen Brucella abortus. Importantly, these different inflammatory stimuli have distinct mechanisms of IRE1α activation; while Toll-like receptor 4 (TLR4) supports glycolysis under both conditions, TLR4 is required for activation of IRE1α in response to LPS treatment but not B. abortus infection. Though IRE1α and XBP1 are necessary for maximal induction of glycolysis in CAMs, activation of this pathway is not sufficient to increase the glycolytic rate of macrophages, indicating that the cellular context in which this pathway is activated ultimately dictates the cell's metabolic response and that IRE1α activation may be a way to fine-tune metabolic reprogramming. IMPORTANCE The immune system must be able to tailor its response to different types of pathogens in order to eliminate them and protect the host. When confronted with bacterial pathogens, macrophages, frontline defenders in the immune system, switch to a glycolysis-driven metabolism to carry out their antibacterial functions. Here, we show that IRE1α, a sensor of ER stress, and its downstream transcription factor XBP1 support glycolysis in macrophages during infection with Brucella abortus or challenge with Salmonella LPS. Interestingly, these stimuli activate IRE1α by independent mechanisms. While the IRE1α-XBP1 signaling axis promotes the glycolytic switch, activation of this pathway is not sufficient to increase glycolysis in macrophages. This study furthers our understanding of the pathways that drive macrophage immunometabolism and highlights a new role for IRE1α and XBP1 in innate immunity.

IL-6/ERK signaling pathway participates in type I IFN-programmed, unconventional M2-like macrophage polarization

Type I interferons (IFN-Is) have been harnessed for cancer therapies due to their immunostimulatory functions. However, certain tumor-tolerating activities by IFN-Is also exist, and may potentially thwart their therapeutic effects. In this respect, our previous studies have demonstrated a monocyte-orchestrated, IFN-I-to-IL-4 cytokine axis, which can subsequently drive M2-skewed pro-tumoral polarization of macrophages. Whether other IFN-dependent signals may also contribute to such an unconventional circumstance of M2-like macrophage skewing remain unexplored. Herein, we first unveil IL-6 as another ligand that participates in IFN-dependent induction of a typical M2 marker (ARG1) in transitional monocytes. Indeed, IL-6 significantly promotes IL-4-dependent induction of a major group of prominent M2 markers in mouse bone marrow-derived macrophages (BMDMs) and human peripheral blood-derived macrophages, while it alone does not engage marked increases of these markers. Such a pattern of regulation is confirmed globally by RNAseq analyses in BMDMs, which in turn suggests an association of IL-6-amplified subset of M2 genes with the ERK1/2 signaling pathway. Interestingly, pharmacological experiments establish the role of SHP2-ERK cascade in mediating IL-6's enhancement effect on these M2 targets. Similar approaches also validate the involvement of IL-6/ERK signaling in promoting the IFN-dependent, unconventional M2-skewing phenotype in transitional monocytes. Furthermore, an inhibitor of ERK signaling cooperates with an IFN-I inducer to enable a greater antitumor effect, which correlates with suppression of treatment-elicited ARG1. The present work establishes a role of IL-6/ERK signaling in promoting M2-like macrophage polarization, and suggests this axis as a potential therapeutic target for combination with IFN-I-based cancer treatments.

The role of innate immune cells in the tumor microenvironment and research progress in anti-tumor therapy

Innate immune cells in the tumor microenvironment (TME) mainly include macrophages, neutrophils, natural killer cells, dendritic cells and bone marrow derived suppressor cells. They play an anti-tumor or pro-tumor role by secreting various cytokines, chemokines and other factors, and determine the occurrence and development of tumors. Comprehending the role of innate immune cells in tumorigenesis and progression can help improve therapeutic approaches targeting innate immune cells in the TME, increasing the likelihood of favorable prognosis. In this review, we discussed the cell biology of innate immune cells, their role in tumorigenesis and development, and the current status of innate immune cell-based immunotherapy, in order to provide an overview for future research lines and clinical trials.

Tumor-intrinsic IRE1α signaling controls protective immunity in lung cancer

IRE1α-XBP1 signaling is emerging as a central orchestrator of malignant progression and immunosuppression in various cancer types. Employing a computational XBP1s detection method applied to TCGA datasets, we demonstrate that expression of the XBP1s mRNA isoform predicts poor survival in non-small cell lung cancer (NSCLC) patients. Ablation of IRE1α in malignant cells delays tumor progression and extends survival in mouse models of NSCLC. This protective effect is accompanied by alterations in intratumoral immune cell subsets eliciting durable adaptive anti-cancer immunity. Mechanistically, cancer cell-intrinsic IRE1α activation sustains mPGES-1 expression, enabling production of the immunosuppressive lipid mediator prostaglandin E2. Accordingly, restoring mPGES-1 expression in IRE1αKO cancer cells rescues normal tumor progression. We have developed an IRE1α gene signature that predicts immune cell infiltration and overall survival in human NSCLC. Our study unveils an immunoregulatory role for cancer cell-intrinsic IRE1α activation and suggests that targeting this pathway may help enhance anti-tumor immunity in NSCLC.

Cysteine cathepsins: A long and winding road towards clinics

Biomedical research often focuses on properties that differentiate between diseased and healthy tissue; one of the current focuses is elevated expression and altered localisation of proteases. Among these proteases, dysregulation of cysteine cathepsins can frequently be observed in inflammation-associated diseases, which tips the functional balance from normal physiological to pathological manifestations. Their overexpression and secretion regularly exhibit a strong correlation with the development and progression of such diseases, making them attractive pharmacological targets. But beyond their mostly detrimental role in inflammation-associated diseases, cysteine cathepsins are physiologically highly important enzymes involved in various biological processes crucial for maintaining homeostasis and responding to different stimuli. Consequently, several challenges have emerged during the efforts made to translate basic research data into clinical applications. In this review, we present both physiological and pathological roles of cysteine cathepsins and discuss the clinical potential of cysteine cathepsin-targeting strategies for disease management and diagnosis.

Hematotoxic Effect of Respiratory Exposure to PHMG-p and Its Integrated Genetic Analysis

Polyhexamethylene guanidine phosphate (PHMG-p), the main ingredient of humidifier disinfectants, circulates systemically through the lungs; however, its toxicological assessment has been primarily limited to pulmonary disease. Herein, we investigated the possible abnormalities in hematopoietic function 20 weeks after intratracheal instillation of PHMG-p in a rat model. Notable abnormalities were found out in the peripheral blood cell count and bone marrow (BM) biopsy, while RNA sequencing of BM tissue revealed markedly altered gene expression. Furthermore, signaling involved in hematopoietic dysfunction was predicted by analyzing candidate genes through Ingenuity Pathway Analysis (IPA) program. Respiratory PHMG-p exposure significantly decreased monocyte and platelet (PLT) counts and total protein, while significantly increasing hemoglobin and hematocrit levels in peripheral blood. Histopathological analysis of the BM revealed a reduced number of megakaryocytes, with no significant differences in spleen and liver weight to body weight. Moreover, PHMG-p exposure significantly activated estrogen receptor signaling and RHOA signaling, and inhibited RHOGDI signaling. In IPA analysis, candidate genes were found to be strongly related to 'hematological system development and function' and 'hematological disease.' Accordingly, our results suggest that PHMG-p could affect hematopoiesis, which participates in monocyte differentiation and PLT production, and may induce hematologic diseases via the respiratory tract.

Decoding endoplasmic reticulum stress signals in cancer cells and antitumor immunity

The tumor microenvironment (TME) provokes endoplasmic reticulum (ER) stress in malignant cells and infiltrating immune populations. Sensing and responding to ER stress is coordinated by the unfolded protein response (UPR), an integrated signaling pathway governed by three ER stress sensors: activating transcription factor (ATF6), inositol-requiring enzyme 1α (IRE1α), and protein kinase R (PKR)-like ER kinase (PERK). Persistent UPR activation modulates malignant progression, tumor growth, metastasis, and protective antitumor immunity. Hence, therapies targeting ER stress signaling can be harnessed to elicit direct tumor killing and concomitant anticancer immunity. We highlight recent findings on the role of the ER stress responses in onco-immunology, with an emphasis on genetic vulnerabilities that render tumors highly sensitive to therapeutic UPR modulation.

The role of cathepsin S in the pathophysiology of bronchial asthma

To date, the study of the role of proteases in the pathogenesis of various diseases remains relevant. The variety of cathepsin functions is associated with the peculiarities of their localization, expression, and regulation, due to which cathepsins are involved in development of many pathologies. Dysregulation of proteases, their inhibitors, and substrates can lead to the development of multiple organ dysfunction.

The review presents data on the characteristics of the entire family of cathepsins and cathepsin S, in particular. The pathophysiological role of cathepsin S in the formation of bronchopulmonary pathologies, as well as in bronchial asthma is described, and intraand extracellular implementation mechanisms are considered. The authors believe it is this enzyme that could be targeted in targeted asthma therapy to prevent airway wall remodeling at the earliest stages of the disease. The literature search was carried out in the search engines Medline, eLibrary, Scopus, the Cochrane Library, and RSCI.

Central Roles of STAT3-Mediated Signals in Onset and Development of Cancers: Tumorigenesis and Immunosurveillance

Since the time of Rudolf Virchow in the 19th century, it has been well-known that cancer-associated inflammation contributes to tumor initiation and progression. However, it remains unclear whether a collapse of the balance between the antitumor immune response via the immunological surveillance system and protumor immunity due to cancer-related inflammation is responsible for cancer malignancy. The majority of inflammatory signals affect tumorigenesis by activating signal transducer and activation of transcription 3 (STAT3) and nuclear factor-κB. Persistent STAT3 activation in malignant cancer cells mediates extremely widespread functions, including cell growth, survival, angiogenesis, and invasion and contributes to an increase in inflammation-associated tumorigenesis. In addition, intracellular STAT3 activation in immune cells causes suppressive effects on antitumor immunity and leads to the differentiation and mobilization of immature myeloid-derived cells and tumor-associated macrophages. In many cancer types, STAT3 does not directly rely on its activation by oncogenic mutations but has important oncogenic and malignant transformation-associated functions in both cancer and stromal cells in the tumor microenvironment (TME). We have reported a series of studies aiming towards understanding the molecular mechanisms underlying the proliferation of various types of tumors involving signal-transducing adaptor protein-2 as an adaptor molecule that modulates STAT3 activity, and we recently found that AT-rich interactive domain-containing protein 5a functions as an mRNA stabilizer that orchestrates an immunosuppressive TME in malignant mesenchymal tumors. In this review, we summarize recent advances in our understanding of the functional role of STAT3 in tumor progression and introduce novel molecular mechanisms of cancer development and malignant transformation involving STAT3 activation that we have identified to date. Finally, we discuss potential therapeutic strategies for cancer that target the signaling pathway to augment STAT3 activity.

STAT3 Signaling in Breast Cancer: Multicellular Actions and Therapeutic Potential

Simple Summary

Many signaling pathways are overactive in breast cancer, and among them is the STAT3 signaling pathway. STAT3 is activated by secreted factors within the breast tumor, many of which are elevated and correlate to advanced disease and poor survival outcomes. This review examines how STAT3 signaling is activated in breast cancer by the proinflammatory, gp130 cytokines, interleukins 6 and 11. We evaluate how this signaling cascade functions in the various cells of the tumor microenvironment to drive disease progression and metastasis. We discuss how our understanding of these processes may lead to the development of novel therapeutics to tackle advanced disease.

Abstract

Interleukin (IL)-6 family cytokines, such as IL-6 and IL-11, are defined by the shared use of the gp130 receptor for the downstream activation of STAT3 signaling and the activation of genes which contribute to the “hallmarks of cancer”, including proliferation, survival, invasion and metastasis. Increased expression of these cytokines, or the ligand-specific receptors IL-6R and IL-11RA, in breast tumors positively correlate to disease progression and poorer patient outcome. In this review, we examine evidence from pre-clinical studies that correlate enhanced IL-6 and IL-11 mediated gp130/STAT3 signaling to the progression of breast cancer. Key processes by which the IL-6 family cytokines contribute to the heterogeneous nature of breast cancer, immune evasion and metastatic potential, are discussed. We examine the latest research into the therapeutic targeting of IL-6 family cytokines that inhibit STAT3 transcriptional activity as a potential breast cancer treatment, including current clinical trials. The importance of the IL-6 family of cytokines in cellular processes that promote the development and progression of breast cancer warrants further understanding of the molecular basis for its actions to help guide the development of future therapeutic targets.

Reprogramming Carbohydrate Metabolism in Cancer and Its Role in Regulating the Tumor Microenvironment

Altered metabolism has become an emerging feature of cancer cells impacting their proliferation and metastatic potential in myriad ways. Proliferating heterogeneous tumor cells are surrounded by other resident or infiltrating cells, along with extracellular matrix proteins, and other secretory factors constituting the tumor microenvironment. The diverse cell types of the tumor microenvironment exhibit different molecular signatures that are regulated at their genetic and epigenetic levels. The cancer cells elicit intricate crosstalks with these supporting cells, exchanging essential metabolites which support their anabolic processes and can promote their survival, proliferation, EMT, angiogenesis, metastasis and even therapeutic resistance. In this context, carbohydrate metabolism ensures constant energy supply being a central axis from which other metabolic and biosynthetic pathways including amino acid and lipid metabolism and pentose phosphate pathway are diverged. In contrast to normal cells, increased glycolytic flux is a distinguishing feature of the highly proliferative cancer cells, which supports them to adapt to a hypoxic environment and also protects them from oxidative stress. Such rewired metabolic properties are often a result of epigenetic alterations in the cancer cells, which are mediated by several factors including, DNA, histone and non-histone protein modifications and non-coding RNAs. Conversely, epigenetic landscapes of the cancer cells are also dictated by their diverse metabolomes. Altogether, this metabolic and epigenetic interplay has immense potential for the development of efficient anti-cancer therapeutic strategies. In this book chapter we emphasize upon the significance of reprogrammed carbohydrate metabolism in regulating the tumor microenvironment and cancer progression, with an aim to explore the different metabolic and epigenetic targets for better cancer treatment.

Therapeutic potential of targeting cathepsin S in pulmonary fibrosis

Cathepsin S (CTSS), a lysosomal protease, belongs to a family of cysteine cathepsin proteases that promote degradation of damaged proteins in the endolysosomal pathway. Aberrant CTSS expression and regulation are associated with the pathogenesis of several diseases, including lung diseases. CTSS overexpression causes a variety of pathological processes, including pulmonary fibrosis, with increased CTSS secretion and accelerated extracellular matrix remodeling. Compared to many other cysteine cathepsin family members, CTSS has unique features that it presents limited tissue expression and retains its enzymatic activity at a neutral pH, suggesting its decisive involvement in disease microenvironments. In this review, we investigated the role of CTSS in lung disease, exploring recent studies that have indicated that CTSS mediates fibrosis in unique ways, along with its structure, substrates, and distinct regulation. We also outlined examples of CTSS inhibitors in clinical and preclinical development and proposed CTSS as a potential therapeutic target for pulmonary fibrosis.

Tumor-induced reshuffling of lipid composition on the endoplasmic reticulum membrane sustains macrophage survival and pro-tumorigenic activity

Tumor-associated macrophages (TAMs) display pro-tumorigenic phenotypes for supporting tumor progression in response to microenvironmental cues imposed by tumor and stromal cells. However, the underlying mechanisms by which tumor cells instruct TAM behavior remain elusive. Here, we uncover that tumor-cell-derived glucosylceramide stimulated unconventional endoplasmic reticulum (ER) stress responses by inducing reshuffling of lipid composition and saturation on the ER membrane in macrophages, which induced IRE1-mediated spliced XBP1 production and STAT3 activation. The cooperation of spliced XBP1 and STAT3 reinforced the pro-tumorigenic phenotype and expression of immunosuppressive genes. Ablation of XBP1 expression with genetic manipulation or ameliorating ER stress responses by facilitating LPCAT3-mediated incorporation of unsaturated lipids to the phosphatidylcholine hampered pro-tumorigenic phenotype and survival in TAMs. Together, we uncover the unexpected roles of tumor-cell-produced lipids that simultaneously orchestrate macrophage polarization and survival in tumors via induction of ER stress responses and reveal therapeutic targets for sustaining host antitumor immunity.

A Complex Metabolic Network Confers Immunosuppressive Functions to Myeloid-Derived Suppressor Cells (MDSCs) within the Tumour Microenvironment

Myeloid-derived suppressor cells (MDSCs) constitute a plastic and heterogeneous cell population among immune cells within the tumour microenvironment (TME) that support cancer progression and resistance to therapy. During tumour progression, cancer cells modify their metabolism to sustain an increased energy demand to cope with uncontrolled cell proliferation and differentiation. This metabolic reprogramming of cancer establishes competition for nutrients between tumour cells and leukocytes and most importantly, among tumour-infiltrating immune cells. Thus, MDSCs that have emerged as one of the most decisive immune regulators of TME exhibit an increase in glycolysis and fatty acid metabolism and also an upregulation of enzymes that catabolise essential metabolites. This complex metabolic network is not only crucial for MDSC survival and accumulation in the TME but also for enhancing immunosuppressive functions toward immune effectors. In this review, we discuss recent progress in the field of MDSC-associated metabolic pathways that could facilitate therapeutic targeting of these cells during cancer progression.

Dual Inhibition of Endoplasmic Reticulum Stress and Oxidation Stress Manipulates the Polarization of Macrophages under Hypoxia to Sensitize Immunotherapy

M2-tumor associated macrophages (TAMs) play an important role in tumor genesis, progression, and metastasis, and repolarizing M2-TAMs to immune-promoting M1 type is increasingly recognized as a promising strategy against the clinically intractable carcinomas. It is observed that M2 macrophages have a high tropism to the tumor hypoxic area, with their endoplasmic reticulum (ER) stress-associated IRE1-XBP1 pathway activated to inhibit cell glycolysis, promote oxidative phosphorylation (OXPHOS), and facilitate intracellular lipid accumulation, which in turn shapes the typical phenotypes of M2-TAMs, suggesting that manipulating the ER stress response of M2-TAMs might stand as a breakthrough for antitumor therapy. However, current attempts to repolarize M2 cells remain limited and are greatly challenged by the hypoxic nature of tumors. Also, the high level of reactive oxygen species (ROS) in the tumor microenvironment (TME) is favorable for the polarization of M2-TAMs. Here, we encapsulated KIRA6, an inhibitor of the IRE1-XBP1 pathway, into a reductive nanoemulsion containing α-tocopherol. Our α-T-K had dual inhibitory effects on the ER stress and oxidative stress. Both in vitro and in vivo experiments suggested that α-T-K effectively reprogrammed M2 macrophages even under hypoxia, achieved by increasing glycolysis and suppressing fatty acid oxidation (FAO). In addition, our data revealed that α-T-K not only delayed tumor growth but elevated the curative effect of PD-1 antibody. Our research demonstrated that simultaneous inhibition of ER stress and oxidative stress could effectively repolarize M2-TAMs under hypoxia, which not only filled the current gap in regulating the biological repolarization of macrophages under hypoxia but provided a meaningful reference for the clinical immunotherapy of sensitized anti-PD-1.

Molecular probes for selective detection of cysteine cathepsins

Cysteine cathepsins are proteases critical in physiopathological processes and show potential as targets or biomarkers for diseases and medical conditions. The 11 members of the cathepsin family are redundant in some cases but remarkably independent of others, demanding the development of both pan-cathepsin targeting tools as well as probes that are selective for specific cathepsins with little off-target activity. This review addresses the diverse design strategies that have been employed to accomplish this tailored selectivity among cysteine cathepsin targets and the imaging modalities incorporated. The power of these diverse tools is contextualized by briefly highlighting the nature of a few prominent cysteine cathepsins, their involvement in select diseases, and the application of cathepsin imaging probes in research spanning basic biochemical studies to clinical applications.

Genome-wide transcriptome analysis of the STAT6-regulated genes in advanced-stage cutaneous T-cell lymphoma

The signal transducer and activator of transcription 6 (STAT6) is a critical up-stream mediator of interleukin-13 (IL-13) and IL-4 signaling and is constitutively activated in malignant lymphocytes from Sezary syndrome (SS) and mycosis fungoides (MF), the most common subtypes of cutaneous T-cell lymphomas. By combining genome-wide expression profiling with pharmacological STAT6 inhibition, we have identified the genes regulated by STAT6 in MF/SS tumors. We found that STAT6 regulates several common pathways in MF/SS malignant lymphocytes that are associated with control of cell-cycle progression and genomic stability as well as production of Th2 cytokines. Using ex vivo skin explants from cutaneous MF tumors as well as Sezary cells derived from the blood of SS patients, we demonstrated that inhibition of STAT6 activation downregulates cytokine production and induces cell-cycle arrest in MF/SS malignant lymphocytes, inhibiting their proliferation but not their survival. Furthermore, we show that STAT6 promotes the protumoral M2-like phenotype of tumor-associated macrophages in the tumor microenvironment of advanced stage MF by upregulating the expression of genes associated with immunosuppression, chemotaxis, and tumor matrix remodeling. Thus, we show STAT6 to be a major factor in the pathogenesis and progression of MF/SS, promoting proliferation and invasion of the malignant lymphocytes while inducing a progressive depression of the antitumor immune response. Together, our results provide new insights into disease pathogenesis and offer new prospective targets for therapeutic intervention.

Endoplasmic Reticulum Stress and Tumor Microenvironment in Bladder Cancer: The Missing Link

Bladder cancer is a common malignant tumor of the urinary system. Despite recent advances in treatments such as local or systemic immunotherapy, chemotherapy, and radiotherapy, the high metastasis and recurrence rates, especially in muscle-invasive bladder cancer (MIBC), have led to the evaluation of more targeted and personalized approaches. A fundamental understanding of the tumorigenesis of bladder cancer along with the development of therapeutics to target processes and pathways implicated in bladder cancer has provided new avenues for the management of this disease. Accumulating evidence supports that the tumor microenvironment (TME) can be shaped by and reciprocally act on tumor cells, which reprograms and regulates tumor development, metastasis, and therapeutic responses. A hostile TME, caused by intrinsic tumor attributes (e.g., hypoxia, oxidative stress, and nutrient deprivation) or external stressors (e.g., chemotherapy and radiation), disrupts the normal synthesis and folding process of proteins in the endoplasmic reticulum (ER), culminating in a harmful situation called ER stress (ERS). ERS is a series of adaptive changes mediated by unfolded protein response (UPR), which is interwoven into a network that can ultimately mediate cell proliferation, apoptosis, and autophagy, thereby endowing tumor cells with more aggressive behaviors. Moreover, recent studies revealed that ERS could also impede the efficacy of anti-cancer treatment including immunotherapy by manipulating the TME. In this review, we discuss the relationship among bladder cancer, ERS, and TME; summarize the current research progress and challenges in overcoming therapeutic resistance; and explore the concept of targeting ERS to improve bladder cancer treatment outcomes.

Role of lysosomes in physiological activities, diseases, and therapy

Long known as digestive organelles, lysosomes have now emerged as multifaceted centers responsible for degradation, nutrient sensing, and immunity. Growing evidence also implicates role of lysosome-related mechanisms in pathologic process. In this review, we discuss physiological function of lysosomes and, more importantly, how the homeostasis of lysosomes is disrupted in several diseases, including atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, lysosomal storage disorders, and malignant tumors. In atherosclerosis and Gaucher disease, dysfunction of lysosomes changes cytokine secretion from macrophages, partially through inflammasome activation. In neurodegenerative diseases, defect autophagy facilitates accumulation of toxic protein and dysfunctional organelles leading to neuron death. Lysosomal dysfunction has been demonstrated in pathology of pancreatitis. Abnormal autophagy activation or inhibition has been revealed in autoimmune disorders. In tumor microenvironment, malignant phenotypes, including tumorigenesis, growth regulation, invasion, drug resistance, and radiotherapy resistance, of tumor cells and behaviors of tumor-associated macrophages, fibroblasts, dendritic cells, and T cells are also mediated by lysosomes. Based on these findings, a series of therapeutic methods targeting lysosomal proteins and processes have been developed from bench to bedside. In a word, present researches corroborate lysosomes to be pivotal organelles for understanding pathology of atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, and lysosomal storage disorders, and malignant tumors and developing novel therapeutic strategies.

Redefining macrophage and neutrophil biology in the metastatic cascade

Tumor cells metastasize to distant organs through a complex series of events that are driven by tumor intrinsic and extrinsic factors. In particular, non-malignant stromal cells, including immune cells, modify tumor metastatic behavior. Of these cells, tumor-associated innate immune cells, particularly macrophages and neutrophils, suppress the cytotoxic activity of innate and adaptive killer cells and interact with tumor cells to promote their growth and malignancy. These findings in mouse cancer models suggest that targeting these sub-populations of immune cells holds therapeutic promise in treating metastatic disease. In this review, we describe the origin and role of the macrophages, neutrophils, and their progenitors in the metastatic cascade and suggest strategies that might enhance cancer therapy.

STAT6: A review of a signaling pathway implicated in various diseases with a special emphasis in its usefulness in pathology

Signal Transducer and Activator of Transcription 6 (STAT6), belonging to a family of seven similar members is primarily stimulated by interleukin(IL)-4 and IL-13, and acts as a T helper type 2 (Th2)-inducing factor. Thus, it is implicated in the pathophysiology of various allergic conditions, such as asthma, atopic dermatitis, eosinophilic esophagitis and food allergies, but also in tumor microenvironment regulation. Furthermore, certain forms of lymphomas, notably the Hodgkin lymphoma group, the primary mediastinal and primary central nervous system lymphoma, as well as some follicular and T cell lymphomas are associated with dysregulation of the STAT6 pathway. STAT6 immunohistochemical expression also serves as a surrogate marker in the diagnosis of solitary fibrous tumor, despite not directly responsible for the tumorigenic effect. These pathophysiological implications of the STAT6 pathway, its diagnostic or prognostic role in pathology, as well its immunohistochemical detection with different antibodies will be discussed in this review.

TGR5/Cathepsin E signaling regulates macrophage innate immune activation in liver ischemia and reperfusion injury

The role and underlying mechanism of plasma membrane-bound G protein-coupled bile acid receptor (TGR5) in regulating macrophage innate immune activation during liver ischemia and reperfusion (IR) injury remains largely unclear. Here, we demonstrated that TGR5 depletion in myeloid cells aggravated liver injury with increased macrophage infiltration and enhanced inflammation in livers post-IR. While TGR5 deficiency enhanced mobility and proinflammatory M1 polarization of macrophages, TGR5 agonist enhanced the anti-inflammatory effect of TGR5 both in vivo and in vitro. Microarray profiling revealed that TGR5-deficient macrophages exhibited enhanced proinflammatory characteristics and cathepsin E (Cat E) was the most upregulated gene. Knockdown of Cat E abolished the enhanced mobility and shift of macrophage phenotypes induced by TGR5 depletion. Moreover, Cat E knockdown attenuated liver IR injury and liver inflammation in myeloid TGR5-deficient mice. In patients undergoing partial hepatectomy, IR stress promoted TGR5 activation of CD11b+ cells in peripheral blood mononuclear cells, correlating with the shift in macrophage M2 polarization. Ursodeoxycholic acid administration enhanced TGR5 activation and the trend in macrophage M2 polarization. Our results suggest that TGR5 attenuates proinflammatory immune activation by restraining macrophage migration and facilitating macrophage M2 polarization via suppression of Cat E and thereby protects against liver IR injury.

A bi-directional dialog between vascular cells and monocytes/macrophages regulates tumor progression

Cancer progression largely depends on tumor blood vessels as well on immune cell infiltration. In various tumors, vascular cells, namely endothelial cells (ECs) and pericytes, strongly regulate leukocyte infiltration into tumors and immune cell activation, hence the immune response to cancers. Recently, a lot of compelling studies unraveled the molecular mechanisms by which tumor vascular cells regulate monocyte and tumor-associated macrophage (TAM) recruitment and phenotype, and consequently tumor progression. Reciprocally, TAMs and monocytes strongly modulate tumor blood vessel and tumor lymphatic vessel formation by exerting pro-angiogenic and lymphangiogenic effects, respectively. Finally, the interaction between monocytes/TAMs and vascular cells is also impacting several steps of the spread of cancer cells throughout the body, a process called metastasis. In this review, the impact of the bi-directional dialog between blood vascular cells and monocytes/TAMs in the regulation of tumor progression is discussed. All together, these data led to the design of combinations of anti-angiogenic and immunotherapy targeting TAMs/monocyte whose effects are briefly discussed in the last part of this review.

Lysosome (Dys)function in Atherosclerosis-A Big Weight on the Shoulders of a Small Organelle

Atherosclerosis is a progressive insidious chronic disease that underlies most of the cardiovascular pathologies, including myocardial infarction and ischemic stroke. The malfunctioning of the lysosomal compartment has a central role in the etiology and pathogenesis of atherosclerosis. Lysosomes are the degradative organelles of mammalian cells and process endogenous and exogenous substrates in a very efficient manner. Dysfunction of these organelles and consequent inefficient degradation of modified low-density lipoproteins (LDL) and apoptotic cells in atherosclerotic lesions have, therefore, numerous deleterious consequences for cellular homeostasis and disease progression. Lysosome dysfunction has been mostly studied in the context of the inherited lysosomal storage disorders (LSDs). However, over the last years it has become increasingly evident that the consequences of this phenomenon are more far-reaching, also influencing the progression of multiple acquired human pathologies, such as neurodegenerative diseases, cancer, and cardiovascular diseases (CVDs). During the formation of atherosclerotic plaques, the lysosomal compartment of the various cells constituting the arterial wall is under severe stress, due to the tremendous amounts of lipoproteins being processed by these cells. The uncontrolled uptake of modified lipoproteins by arterial phagocytic cells, namely macrophages and vascular smooth muscle cells (VSMCs), is the initial step that triggers the pathogenic cascade culminating in the formation of atheroma. These cells become pathogenic "foam cells," which are characterized by dysfunctional lipid-laden lysosomes. Here, we summarize the current knowledge regarding the origin and impact of the malfunctioning of the lysosomal compartment in plaque cells. We further analyze how the field of LSD research may contribute with some insights to the study of CVDs, particularly how therapeutic approaches that target the lysosomes in LSDs could be applied to hamper atherosclerosis progression and associated mortality.

Wnt signaling enhances macrophage responses to IL-4 and promotes resolution of atherosclerosis

Atherosclerosis is a disease of chronic inflammation. We investigated the roles of the cytokines IL-4 and IL-13, the classical activators of STAT6, in the resolution of atherosclerosis inflammation. Using Il4-/-Il13-/- mice, resolution was impaired, and in control mice, in both progressing and resolving plaques, levels of IL-4 were stably low and IL-13 was undetectable. This suggested that IL-4 is required for atherosclerosis resolution, but collaborates with other factors. We had observed increased Wnt signaling in macrophages in resolving plaques, and human genetic data from others showed that a loss-of-function Wnt mutation was associated with premature atherosclerosis. We now find an inverse association between activation of Wnt signaling and disease severity in mice and humans. Wnt enhanced the expression of inflammation resolving factors after treatment with plaque-relevant low concentrations of IL-4. Mechanistically, activation of the Wnt pathway following lipid lowering potentiates IL-4 responsiveness in macrophages via a PGE2/STAT3 axis.

Chemically based transmissible ER stress protocols are unsuitable to study cell-to-cell UPR transmission

Renal epithelial cells regulate the destructive activity of macrophages and participate in the progression of kidney diseases. Critically, the Unfolded Protein Response (UPR), which is activated in renal epithelial cells in the course of kidney injury, is required for the optimal differentiation and activation of macrophages. Given that macrophages are key regulators of renal inflammation and fibrosis, we suppose that the identification of mediators that are released by renal epithelial cells under Endoplasmic Reticulum (ER) stress and transmitted to macrophages is a critical issue to address. Signals leading to a paracrine transmission of ER stress (TERS) from a donor cell to a recipient cells could be of paramount importance to understand how ER-stressed cells shape the immune microenvironment. Critically, the vast majority of studies that have examined TERS used thaspigargin as an inducer of ER stress in donor cells in cellular models. By using multiple sources of ER stress, we evaluated if human renal epithelial cells undergoing ER stress can transmit the UPR to human monocyte-derived macrophages and if such TERS can modulate the inflammatory profiles of these cells. Our results indicate that carry-over of thapsigargin is a confounding factor in chemically based TERS protocols classically used to induce ER Stress in donor cells. Hence, such protocols are not suitable to study the TERS phenomenon and to identify its mediators. In addition, the absence of TERS transmission in more physiological models of ER stress indicates that cell-to-cell UPR transmission is not a universal feature in cultured cells.

Prognostic significance and targeting tumor-associated macrophages in cancer: new insights and future perspectives

Macrophages are phagocytic sentinel cells of the immune system that are central to both innate and adaptive immune responses and serve as the first line of defense against pathogenic insults to tissues. In the tumor microenvironment, tumor-derived factors induce monocyte polarization towards a pro-tumor phenotype. The pro-tumor macrophages regulate key steps in tumorigenicity including tumor growth, angiogenesis, immune suppression, and metastasis. Macrophage infiltration in solid tumors correlates with poor prognosis and resistance to chemotherapy in most cancers. Here in this review, we will shed light on tumor-associated macrophages (TAMs) in regulating tumorigenicity and TAMs as a prognostic biomarker. Also, we will review the recent advances in targeting TAMs to increase the prognosis of cancer patients.

Rab22a-NeoF1 fusion protein promotes osteosarcoma lung metastasis through its secretion into exosomes

It remains unknown for decades how some of the therapeutic fusion proteins positive in a small percentage of cancer cells account for patient outcome. Here, we report that osteosarcoma Rab22a-NeoF1 fusion protein, together with its binding partner PYK2, is sorted into exosomes by HSP90 via its KFERQ-like motif (RVLFLN¹⁴²). The exosomal Rab22a-NeoF1 fusion protein facilitates the pulmonary pre-metastatic niche formation by recruiting bone marrow-derived macrophages. The exosomal PYK2 activates RhoA in its negative recipient osteosarcoma cells and induces signal transducer and activator of transcription 3 activation in its recipient macrophages to increase M2 phenotype. Consequently, lung metastases of its recipient osteosarcoma cells are promoted by this exosomal Rab22a-NeoF1 fusion protein, and this event can be targeted by disrupting its interaction with PYK2 using a designed internalizing RGD peptide.

Autophagy in Acute Pancreatitis: Organelle Interaction and microRNA Regulation

Acute pancreatitis (AP) is a common disorder with significant hospital admission and mortality. Due to the unclarified pathological mechanism, there is still no effective and specific treatment for AP. Recently, autophagy has been found to be closely related with occurrence and development of AP, which is crucial in determining its severity and outcomes. Emerging evidence indicates that autophagy can be regulated and influenced by microRNAs and organelles, including mitochondria, endoplasmic reticulum and lysosome, through various ways in AP. Of note, the complex interplays and close relationships among autophagy, microRNA and organelles in AP are vital for figuring out pathogenesis but not clear yet. Thus, this review summarizes the role of autophagy in the pathological mechanism of AP, especially the relationship between impaired autophagy and organelles, and discusses the regulatory mechanism of microRNA on autophagy, which could offer new insights into understanding the pathogenesis of AP and developing new potential therapeutic targets against AP.

Endoplasmic reticulum stress signals in the tumour and its microenvironment

Protein handling, modification and folding in the endoplasmic reticulum (ER) are tightly regulated processes that determine cell function, fate and survival. In several tumour types, diverse oncogenic, transcriptional and metabolic abnormalities cooperate to generate hostile microenvironments that disrupt ER homeostasis in malignant and stromal cells, as well as infiltrating leukocytes. These changes provoke a state of persistent ER stress that has been demonstrated to govern multiple pro-tumoural attributes in the cancer cell while dynamically reprogramming the function of innate and adaptive immune cells. Aberrant activation of ER stress sensors and their downstream signalling pathways have therefore emerged as key regulators of tumour growth and metastasis as well as response to chemotherapy, targeted therapies and immunotherapy. In this Review, we discuss the physiological inducers of ER stress in the tumour milieu, the interplay between oncogenic signalling and ER stress response pathways in the cancer cell and the profound immunomodulatory effects of sustained ER stress responses in tumours.

The HSP GRP94 interacts with macrophage intracellular complement C3 and impacts M2 profile during ER stress

The role of GRP94, an endoplasmic reticulum (ER) stress protein with both pro- and anti-inflammatory functions, has not been investigated in macrophages during ER stress, whereas ER stress has been reported in many diseases involving macrophages. In this work, we studied GRP94 in M1/LPS + IFNγ and M2/IL-4 primary macrophages derived from human monocytes (isolated from buffy coats), in basal and ER stress conditions induced by thapsigargin (Tg), an inducer of ER calcium depletion and tunicamycin (Tm), an inhibitor of N-glycosylation. We found that GRP94 was expressed on the membrane of M2 but not M1 macrophages. In M2, Tg, but not Tm, while decreased GRP94 content in the membrane, it induced its secretion. This correlated with the induction of a pro-inflammatory profile, which was dependent on the UPR IRE1α arm activation and on a functional GRP94. As we previously reported that GRP94 associated with complement C3 at the extracellular level, we analyzed C3 and confirmed GRP94-C3 interaction in our experimental model. Further, Tg increased this interaction and, in these conditions, C3b and cathepsin L were detected in the extracellular medium where GRP94 co-immunoprecipitated with C3 and C3b. Finally, we showed that the C3b inactivated fragment, iC3b, only present on non-stressed M2, depended on functional GRP94, making both GRP94 and iC3b potential markers of M2 cells. In conclusion, our results show that GRP94 is co-secreted with C3 under ER stress conditions which may facilitate its cleavage by cathepsin L, thus contributing to the pro-inflammatory profile observed in stressed M2 macrophages.