Triggering MSR1 promotes JNK-mediated inflammation in IL-4-activated macrophages

Engineering M2-type macrophages with a metal polyphenol network for peripheral artery disease treatment

Functional cell treatment for critical limb ischemia is limited by cell viability loss and dysfunction resulting from a harmful ischemic microenvironment. Metal-polyphenol networks have emerged as novel cell delivery vehicles for protecting cells from the detrimental ischemic microenvironment and prolonging the survival rate of cells in the ischemic microenvironment. M2 macrophages are closely related to tissue repair, and they secrete anti-inflammatory factors that contribute to lesion repair. However, these cells are easily metabolized in the body with low efficiency. Herein, M2 macrophages were decorated with a metal‒polyphenol network that contains copper ions and epigallocatechin gallate (Cu-EGCG@M2) to increase cell survival and therapeutic potential. Cu-EGCG@M2 synergistically promoted angiogenesis through the inherent angiogenesis effect of M2 macrophages and copper ions. We found that Cu-EGCG@M2 increased in vitro viability and strengthened the in vivo therapeutic effect on the ischemic hindlimbs of mice, which promoted the recovery of blood and muscle regeneration, resulting in superior limb salvage. These therapeutic effects were ascribed to the increased survival rate and therapeutic period of M2 macrophages, as well as the ameliorated microenvironment at the ischemic site. Additionally, Cu-EGCG exhibited antioxidant, anti-inflammatory, and proangiogenic effects. Our findings provide a feasible option for cell-based treatment of CLI.

Roles of immune dysregulation in MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide. Its occurrence and progression involve the process from simple hepatic steatosis to metabolic dysfunction associated steatohepatitis (MASH), which could develop into advanced liver fibrosis, cirrhosis, or hepatocellular carcinoma (HCC). Growing evidences support that the pathogenesis and progression of MASLD are closely related to immune system dysfunction. This review aims to summarize the association of MASLD with immune disorders and the prospect of using immunotherapy for MASLD.

Soluble CD83 modulates human-monocyte-derived macrophages toward alternative phenotype, function, and metabolism

Alterations in macrophage (Mφ) polarization, function, and metabolic signature can foster development of chronic diseases, such as autoimmunity or fibrotic tissue remodeling. Thus, identification of novel therapeutic agents that modulate human Mφ biology is crucial for treatment of such conditions. Herein, we demonstrate that the soluble CD83 (sCD83) protein induces pro-resolving features in human monocyte-derived Mφ biology. We show that sCD83 strikingly increases the expression of inhibitory molecules including ILT-2 (immunoglobulin-like transcript 2), ILT-4, ILT-5, and CD163, whereas activation markers, such as MHC-II and MSR-1, were significantly downregulated. This goes along with a decreased capacity to stimulate alloreactive T cells in mixed lymphocyte reaction (MLR) assays. Bulk RNA sequencing and pathway analyses revealed that sCD83 downregulates pathways associated with pro-inflammatory, classically activated Mφ (CAM) differentiation including HIF-1A, IL-6, and cytokine storm, whereas pathways related to alternative Mφ activation and liver X receptor were significantly induced. By using the LXR pathway antagonist GSK2033, we show that transcription of specific genes (e.g., PPARG, ABCA1, ABCG1, CD36) induced by sCD83 is dependent on LXR activation. In summary, we herein reveal for the first time mechanistic insights into the modulation of human Mφ biology by sCD83, which is a further crucial preclinical study for the establishment of sCD83 as a new therapeutical agent to treat inflammatory conditions.

Innate Immune Pathways in Atherosclerosis-From Signaling to Long-Term Epigenetic Reprogramming

Innate immune pathways play a crucial role in the development of atherosclerosis, from sensing initial danger signals to the long-term reprogramming of immune cells. Despite the success of lipid-lowering therapy, anti-hypertensive medications, and other measures in reducing complications associated with atherosclerosis, cardiovascular disease (CVD) remains the leading cause of death worldwide. Consequently, there is an urgent need to devise novel preventive and therapeutic strategies to alleviate the global burden of CVD. Extensive experimental research and epidemiological studies have demonstrated the dominant role of innate immune mechanisms in the progression of atherosclerosis. Recently, landmark trials including CANTOS, COLCOT, and LoDoCo2 have provided solid evidence demonstrating that targeting innate immune pathways can effectively reduce the risk of CVD. These groundbreaking trials mark a significant paradigm shift in the field and open new avenues for atheroprotective treatments. It is therefore crucial to comprehend the intricate interplay between innate immune pathways and atherosclerosis for the development of targeted therapeutic interventions. Additionally, unraveling the mechanisms underlying long-term reprogramming may offer novel strategies to reverse the pro-inflammatory phenotype of immune cells and restore immune homeostasis in atherosclerosis. In this review, we present an overview of the innate immune pathways implicated in atherosclerosis, with a specific focus on the signaling pathways driving chronic inflammation in atherosclerosis and the long-term reprogramming of immune cells within atherosclerotic plaque. Elucidating the molecular mechanisms governing these processes presents exciting opportunities for the development of a new class of immunotherapeutic approaches aimed at reducing inflammation and promoting plaque stability. By addressing these aspects, we can potentially revolutionize the management of atherosclerosis and its associated cardiovascular complications.

Deciphering mechanisms of cardiomyocytes and non-cardiomyocyte transformation in myocardial remodeling of permanent atrial fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia, and it significantly increases the risk of cardiovascular complications and morbidity, even with appropriate treatment. Tissue remodeling has been a significant topic, while its systematic transcriptional signature remains unclear in AF.

OBJECTIVES

Our study aims to systematically investigate the molecular characteristics of AF at the cellular-level.

METHODS

We conducted single-nuclei RNA-sequencig (snRNA-seq) analysis using nuclei isolated from the left atrial appendage (LAA) of AF patients and sinus rhythm. Pathological staining was performed to validate the key findings of snRNA-seq.

RESULTS

A total of 30 cell subtypes were identified among 80, 592 nuclei. Within the LAA of AF, we observed a specific subtype of dedifferentiated cardiomyocytes (CMs) characterized by reduced expression of cardiac contractile proteins (TTN and TRDN) and heightened expression of extracellular-matrix related genes (COL1A2 and FBN1). Transcription factor prediction analysis revealed that gene expression patterns in dedifferentiated CMs were primarily regulated by CEBPG and GISLI. Additionally, we identified a distinct subtype of endothelial progenitor cells (EPCs) demonstrating elevated expression of PROM1 and KDR, a population decreased within the LAA of AF. Epicardial adipocytes disclosed a reduced release of the anti-inflammatory and anti-fibrotic factor PRG4, and an augmented secretion of VEGF signals targeting CMs. Additionally, we noted accumulation of M2-like macrophages and CD8+ T cells with high pro-inflammatory score in LAA of AF. Furthermore, the analysis of intercellular communication revealed specific pathways related to AF, such as inflammation, extracellular matrix, and vascular remodeling signals.

CONCLUSIONS

This study has discovered the presence of dedifferentiated CMs, a decrease in endothelial progenitor cells, a shift in the secretion profile of adipocytes, and an amplified inflammatory response in AF. These findings could offer crucial insights for future research on AF and serve as valuable references for investigating novel therapeutic approaches for AF.

Hepatic Fat and Macrophages Are Increased in Livers of Diabetic Patients without Non-Alcoholic Fatty Liver Disease

INTRODUCTION

Diabetes mellitus (DM), especially type 2, is strongly associated with non-alcoholic fatty liver disease (NAFLD). Recent studies indicate that particularly in DM patients, "simple" liver steatosis can progress into more severe disease. However, little is known about putative hepatic histopathological changes in DM patients without NAFLD. In this study, we therefore analysed fat content and inflammatory cell infiltration in the livers of deceased DM and non-DM patients without NAFLD, and analysed age/sex effects hereon.

METHODS

Hepatic fat and inflammatory cells were studied through (immuno)histochemical analysis in liver tissue from 24 DM patients and 66 non-diabetic controls, without histopathological characteristics of NAFLD.

RESULTS

We observed a 2-fold increase in fat percentage/mm2 and a near 5-fold increase in the number of fat-containing cells/mm2 in DM patients compared to non-diabetic controls. Fat content was significantly higher in patients with type 2 DM, but not type 1 DM, compared to non-diabetic controls, while the number of CD68+ cells/mm2 was significantly elevated in both DM groups.

CONCLUSION

Hepatic fat and number of macrophages are increased in patients with DM without NAFLD, which may reflect a higher risk on development of steatosis and steatohepatitis.

Glycyrrhetinic acid suppresses breast cancer metastasis by inhibiting M2-like macrophage polarization via activating JNK1/2 signaling

BACKGROUND

Breast cancer metastasis is leading cause of cancer death among women worldwide. Tumor-associated macrophages (TAMs) have been considered as potential targets for treating breast cancer metastasis because they promote tumor growth and development. Glycyrrhetinic acid (GA) is one of the most important phytochemicals of licorice which has shown promising anti-cancer efficacies in pre-clinical trials. However, the regulatory effect of GA on the polarization of TAMs remains elusive.

PURPOSE

To investigate the role of GA in regulating the polarization of M2 macrophages and inhibiting breast cancer metastasis, and to further explore its underlying mechanisms of action.

STUDY DESIGN

IL-4 / IL-13-treated RAW 264.7 and THP-1 cells were used as the M2-polarized macrophages in vitro. A 4T1 mouse breast cancer model and the tail vein breast cancer metastasis model were applied to study the effect of GA on breast cancer growth and metastasis in vivo.

RESULTS

In vitro studies showed that GA significantly inhibited IL-4 / IL 13-induced M2-like polarization in RAW 264.7 and THP-1 macrophages without affecting M1-like polarization. GA strongly decreased the expression of M2 macrophage markers CD206 and Arg-1, and reduced the levels of the pro-angiogenic molecules VEGF, MMP9, MMP2 and IL-10 in M2 macrophages. GA also increased the phosphorylation of JNK1/2 in M2 macrophages. Moreover, GA significantly suppressed M2 macrophage-induced cell proliferation and migration in 4T1 cancer cells and HUVECs. Interestingly, the inhibitory effects of GA on M2 macrophages were abolished by a JNK inhibitor. Animal studies showed that GA significantly suppressed tumor growth, angiogenesis, and lung metastasis in BALB/c mice bearing breast tumor. In tumor tissues, GA reduced the number of M2 macrophages but elevated the proportion of M1 macrophages, accompanied by activation of JNK signaling. Similar results were found in the tail vein breast cancer metastasis model.

CONCLUSION

This study demonstrated for the first time that GA could effectively suppress breast cancer growth and metastasis by inhibiting macrophage M2 polarization via activating JNK1/2 signaling. These findings indicate that GA could be served as the lead compound for the future development of anti-breast cancer drug.

[Oral Squamous Cell Carcinoma-Derived Cell-Free DNA Modulates Stemness and Migration of Oral Squamous Cell Carcinoma Cell Line by Inducing M2 Macrophage Polarization]

Objective

To investigate the effect of oral squamous cell carcinoma (OSCC)-derived cell-free DNA (cfDNA) on the polarization of macrophages and the regulatory effect of polarized macrophages on the stemness and migration of OSCC cells.

Methods

A total of 30 OSCC tissue samples, 10 dysplastic oral tissue samples, and 10 normal oral tissue samples were collected. The status of all tissue samples was confirmed by pathology analysis. Immunohistochemical (IHC) staining and immunofluorescence (IF) staining were performed to examine the cell count and location of M2 macrophages in different types of oral tissue samples. The conditioned medium (CM) of OSCC cell line CAL-27 from the human tongue was collected and the cfDNA was concentrated and isolated for identification. The macrophages were treated by cfDNA and their morphological characteristics were observed under microscope. The expression levels of polarization-related indicators were determined by RT-qPCR. CAL-27 cell line was treated with macrophage CM induced by cfDNA and the expression levels of stemness-related genes were determined by RT-qPCR. Scratch-wound assay was conducted to verify that the migration ability of CAL-27 was modulated by macrophages induced by cfDNA.

Results

There were more M2 macrophages in the deep connective tissue of dysplastic oral epithelium and the stroma of OSCC compared with those in the normal oral tissues ( P<0.05). OSCC cell line CAL-27 could secret cfDNA of 10000-15000 bp in length. cfDNA secreted by CAL-27 could induced in macrophages significantly higher expression of M2-macrophage-related genes ( P<0.05). cfDNA-treated macrophages induced significantly increased expression of stemness-related genes in CAL-27 cell line ( P<0.05) and promoted the migration ability of CAL-27 cell line ( P<0.05).

Conclusion

OSCC-derived cfDNA promotes stemness and migration of OSCC cell line by inducing M2 macrophage polarization.

Analysis and verification of the circRNA regulatory network RNO_CIRCpedia_ 4214/RNO-miR-667-5p/Msr1 axis as a potential ceRNA promoting macrophage M2-like polarization in spinal cord injury

BACKGROUND

CircRNAs are involved in the pathogenesis of several central nervous system diseases. However, their functions and mechanisms in spinal cord injury (SCI) are still unclear. Therefore, the purpose of this study was to evaluate circRNA and mRNA expression profiles in the pathological setting of SCI and to predict the potential function of circRNA through bioinformatics.

METHODS

A microarray-based approach was used for the simultaneous measurement of circRNAs and mRNAs, together with qPCR, fluorescence in situ hybridization, western immunoblotting, and dual-luciferase reporter assays to investigate the associated regulatory mechanisms in a rat SCI model.

RESULTS

SCI was found to be associated with the differential expression of 414 and 5337 circRNAs and mRNAs, respectively. Pathway enrichment analyses were used to predict the primary function of these circRNAs and mRNAs. GSEA analysis showed that differentially expressed mRNAs were primarily associated with inflammatory immune response activity. Further screening of these inflammation-associated genes was used to construct and analyze a competing endogenous RNA network. RNO_CIRCpedia_4214 was knocked down in vitro, resulting in reduced expression of Msr1, while the expression of RNO-miR-667-5p and Arg1 was increased. Dual-luciferase assays demonstrated that RNO_CIRCpedia_4214 bound to RNO-miR-667-5p. The RNO_CIRCpedia_4214/RNO-miR-667-5p/Msr1 axis may be a potential ceRNA that promotes macrophage M2-like polarization in SCI.

CONCLUSION

Overall, these results highlighted the critical role that circRNAs may play in the pathophysiology of SCI and the discovery of a potential ceRNA mechanism based on novel circRNAs that regulates macrophage polarization, providing new targets for the treatment of SCI.

Lung macrophages utilize unique cathepsin K-dependent phagosomal machinery to degrade intracellular collagen

Resident tissue macrophages are organ-specialized phagocytes responsible for the maintenance and protection of tissue homeostasis. It is well established that tissue diversity is reflected by the heterogeneity of resident tissue macrophage origin and phenotype. However, much less is known about tissue-specific phagocytic and proteolytic macrophage functions. Here, using a quantitative proteomics approach, we identify cathepsins as key determinants of phagosome maturation in primary peritoneum-, lung-, and brain-resident macrophages. The data further uncover cathepsin K (CtsK) as a molecular marker for lung phagosomes required for intracellular protein and collagen degradation. Pharmacological blockade of CtsK activity diminished phagosomal proteolysis and collagenolysis in lung-resident macrophages. Furthermore, profibrotic TGF-β negatively regulated CtsK-mediated phagosomal collagen degradation independently from classical endocytic-proteolytic pathways. In humans, phagosomal CtsK activity was reduced in COPD lung macrophages and non-COPD lung macrophages exposed to cigarette smoke extract. Taken together, this study provides a comprehensive map of how peritoneal, lung, and brain tissue environment shapes phagosomal composition, revealing CtsK as a key molecular determinant of lung phagosomes contributing to phagocytic collagen clearance in lungs.

Integrated transcriptome study of the tumor microenvironment for treatment response prediction in male predominant hypopharyngeal carcinoma

The efficacy of the first-line treatment for hypopharyngeal carcinoma (HPC), a predominantly male cancer, at advanced stage is only about 50% without reliable molecular indicators for its prognosis. In this study, HPC biopsy samples collected before and after the first-line treatment are classified into different groups according to treatment responses. We analyze the changes of HPC tumor microenvironment (TME) at the single-cell level in response to the treatment and identify three gene modules associated with advanced HPC prognosis. We estimate cell constitutions based on bulk RNA-seq of our HPC samples and build a binary classifier model based on non-malignant cell subtype abundance in TME, which can be used to accurately identify treatment-resistant advanced HPC patients in time and enlarge the possibility to preserve their laryngeal function. In summary, we provide a useful approach to identify gene modules and a classifier model as reliable indicators to predict treatment responses in HPC.

Macrophage Polarization: An Important Candidate Regulator for Lung Diseases

Macrophages are crucial components of the immune system and play a critical role in the initial defense against pathogens. They are highly heterogeneous and plastic and can be polarized into classically activated macrophages (M1) or selectively activated macrophages (M2) in response to local microenvironments. Macrophage polarization involves the regulation of multiple signaling pathways and transcription factors. Here, we focused on the origin of macrophages, the phenotype and polarization of macrophages, as well as the signaling pathways associated with macrophage polarization. We also highlighted the role of macrophage polarization in lung diseases. We intend to enhance the understanding of the functions and immunomodulatory features of macrophages. Based on our review, we believe that targeting macrophage phenotypes is a viable and promising strategy for treating lung diseases.

Capturing the multifaceted function of adipose tissue macrophages

Adipose tissue macrophages (ATMs) bolster obesity-induced metabolic dysfunction and represent a targetable population to lessen obesity-associated health risks. However, ATMs also facilitate adipose tissue function through multiple actions, including adipocyte clearance, lipid scavenging and metabolism, extracellular remodeling, and supporting angiogenesis and adipogenesis. Thus, high-resolution methods are needed to capture macrophages' dynamic and multifaceted functions in adipose tissue. Herein, we review current knowledge on regulatory networks critical to macrophage plasticity and their multifaceted response in the complex adipose tissue microenvironment.

MSR1 is not required for obesity-associated inflammation and insulin resistance in mice

Obesity induces a chronic inflammatory state associated with changes in adipose tissue macrophages (ATMs). Macrophage scavenger receptor 1 (MSR1) has been implicated in the regulation of adipose tissue inflammation and diabetes pathogenesis; however, reports have been mixed on the contribution of MSR1 in obesity and glucose intolerance. We observed increased MSR1 expression in VAT of obese diabetic individuals compared to non-diabetic and single nuclear RNA sequencing identified macrophage-specific expression of MSR1 in human adipose tissue. We examined male Msr1-/- (Msr1KO) and WT controls and observed protection from obesity and AT inflammation in non-littermate Msr1KO mice. We then evaluated obese littermate Msr1+/- (Msr1HET) and Msr1KO mice. Both Msr1KO mice and Msr1HET mice became obese and insulin resistant when compared to their normal chow diet counterparts, but there was no Msr1-dependent difference in body weight, glucose metabolism, or insulin resistance. Flow cytometry revealed no significant differences between genotypes in ATM subtypes or proliferation in male and female mice. We observed increased frequency of proliferating ATMs in obese female compared to male mice. Overall, we conclude that while MSR1 is a biomarker of diabetes status in human adipose tissue, in mice Msr1 is not required for obesity-associated insulin resistance or ATM accumulation.

The contradictory roles of macrophages in non-alcoholic fatty liver disease and primary liver cancer-Challenges and opportunities

Chronic liver diseases from varying etiologies generally lead to liver fibrosis and cirrhosis. Among them, non-alcoholic fatty liver disease (NAFLD) affects roughly one-quarter of the world population, thus representing a major and increasing public health burden. Chronic hepatocyte injury, inflammation (non-alcoholic steatohepatitis, NASH) and liver fibrosis are recognized soils for primary liver cancer, particularly hepatocellular carcinoma (HCC), being the third most common cause for cancer-related deaths worldwide. Despite recent advances in liver disease understanding, therapeutic options on pre-malignant and malignant stages remain limited. Thus, there is an urgent need to identify targetable liver disease-driving mechanisms for the development of novel therapeutics. Monocytes and macrophages comprise a central, yet versatile component of the inflammatory response, fueling chronic liver disease initiation and progression. Recent proteomic and transcriptomic studies performed at singular cell levels revealed a previously overlooked diversity of macrophage subpopulations and functions. Indeed, liver macrophages that encompass liver resident macrophages (also named Kupffer cells) and monocyte-derived macrophages, can acquire a variety of phenotypes depending on microenvironmental cues, and thus exert manifold and sometimes contradictory functions. Those functions range from modulating and exacerbating tissue inflammation to promoting and exaggerating tissue repair mechanisms (i.e., parenchymal regeneration, cancer cell proliferation, angiogenesis, fibrosis). Due to these central functions, liver macrophages represent an attractive target for the treatment of liver diseases. In this review, we discuss the multifaceted and contrary roles of macrophages in chronic liver diseases, with a particular focus on NAFLD/NASH and HCC. Moreover, we discuss potential therapeutic approaches targeting liver macrophages.

Protein Arginylation Is Regulated during SARS-CoV-2 Infection

BACKGROUND

In 2019, the world witnessed the onset of an unprecedented pandemic. By February 2022, the infection by SARS-CoV-2 has already been responsible for the death of more than 5 million people worldwide. Recently, we and other groups discovered that SARS-CoV-2 infection induces ER stress and activation of the unfolded protein response (UPR) pathway. Degradation of misfolded/unfolded proteins is an essential element of proteostasis and occurs mainly in lysosomes or proteasomes. The N-terminal arginylation of proteins is characterized as an inducer of ubiquitination and proteasomal degradation by the N-degron pathway.

RESULTS

The role of protein arginylation during SARS-CoV-2 infection was elucidated. Protein arginylation was studied in Vero CCL-81, macrophage-like THP1, and Calu-3 cells infected at different times. A reanalysis of in vivo and in vitro public omics data combined with immunoblotting was performed to measure levels of arginyl-tRNA-protein transferase (ATE1) and its substrates. Dysregulation of the N-degron pathway was specifically identified during coronavirus infections compared to other respiratory viruses. We demonstrated that during SARS-CoV-2 infection, there is an increase in ATE1 expression in Calu-3 and Vero CCL-81 cells. On the other hand, infected macrophages showed no enzyme regulation. ATE1 and protein arginylation was variant-dependent, as shown using P1 and P2 viral variants and HEK 293T cells transfection with the spike protein and receptor-binding domains (RBD). In addition, we report that ATE1 inhibitors, tannic acid and merbromine (MER) reduce viral load. This finding was confirmed in ATE1-silenced cells.

CONCLUSIONS

We demonstrate that ATE1 is increased during SARS-CoV-2 infection and its inhibition has potential therapeutic value.

Multifunctional role of the ubiquitin proteasome pathway in phagocytosis

Phagocytosis is a specialized form of endocytosis where large cells and particles (>0.5μm) are engulfed by the phagocytic cells, and ultimately digested in the phagolysosomes. This process not only eliminates unwanted particles and pathogens from the extracellular sources, but also eliminates apoptotic cells within the body, and is critical for maintenance of tissue homeostasis. It is believed that both endocytosis and phagocytosis share common pathways after particle internalization, but specialized features and differences between these two routes of internalization are also likely. The recruitment and removal of each protein/particle during the maturation of endocytic/phagocytic vesicles has to be tightly regulated to ensure their timely action. Ubiquitin proteasome pathway (UPP), degrades unwanted proteins by post-translational modification of proteins with chains of conserved protein Ubiquitin (Ub), with subsequent recognition of Ub chains by the 26S proteasomes and substrate degradation by this protease. This pathway utilizes different Ub linkages to modify proteins to regulate protein-protein interaction, localization, and activity. Due to its vast number of targets, it is involved in many cellular pathways, including phagocytosis. This chapters describes the basic steps and signaling in phagocytosis and different roles that UPP plays at multiple steps in regulating phagocytosis directly, or through its interaction with other phagosomal proteins. How aberrations in UPP function affect phagocytosis and their association with human diseases, and how pathogens exploit this pathway for their own benefit is also discussed.

Strategies to Overcome Resistance to Immune-Based Therapies in Osteosarcoma

Improving the prognosis and cure rate of HGOSs (high-grade osteosarcomas) is an absolute need. Immune-based treatment approaches have been increasingly taken into consideration, in particular for metastatic, relapsed and refractory HGOS patients, to ameliorate the clinical results currently achieved. This review is intended to give an overview on the immunotherapeutic treatments targeting, counteracting or exploiting the different immune cell compartments that are present in the HGOS tumor microenvironment. The principle at the basis of these strategies and the possible mechanisms that HGOS cells may use to escape these treatments are presented and discussed. Finally, a list of the currently ongoing immune-based trials in HGOS is provided, together with the results that have been obtained in recently completed clinical studies. The different strategies that are presently under investigation, which are generally aimed at abrogating the immune evasion of HGOS cells, will hopefully help to indicate new treatment protocols, leading to an improvement in the prognosis of patients with this tumor.

Assessing the Phagosome Proteome by Quantitative Mass Spectrometry

The process of phagocytosis involves a series of defined steps, including the formation of a new intracellular organelle, i.e., the phagosome, and the maturation of the phagosome by fusion with endosomes and lysosomes to produce an acidic and proteolytic environment in which the pathogens are degraded. Phagosome maturation is associated with significant changes in the proteome of phagosomes due to the acquisition of new proteins or enzymes, post-translational modifications of existing proteins, as well as other biochemical changes that ultimately lead to the degradation or processing of the phagocytosed particle. Phagosomes are highly dynamic organelles formed by the uptake of particles through phagocytic innate immune cells; thus characterization of the phagosomal proteome is essential to understand the mechanisms controlling innate immunity, as well as vesicle trafficking. In this chapter, we describe how novel quantitative proteomics methods, such as using tandem mass tag (TMT) labelling or acquiring label-free data using data-independent acquisition (DIA), can be applied for the characterization of protein composition of phagosomes in macrophages.

Isolation of Polystyrene Bead-Induced Phagosomes for Western Blotting

The engulfment of "self" and "non-self" particles by immune and non-immune cells is crucial for maintaining homeostasis and combatting infection. Engulfed particles are contained within vesicles termed phagosomes that undergo dynamic fusion and fission events, which ultimately results in the formation of phagolysosomes that degrade the internalized cargo. This process is highly conserved and plays an important role in maintaining homeostasis, and disruptions in this are implicated in numerous inflammatory disorders. Given its broad role in innate immunity, it is important to understand how different stimuli or changes within the cell can shape the phagosome architecture. In this chapter, we describe a robust protocol for the isolation of polystyrene bead-induced phagosomes using sucrose density gradient centrifugation. This process results in a highly pure sample that can be used in downstream applications, namely, Western blotting.

Subacute Cadmium Exposure Induces Necroptosis in Swine Lung via Influencing Th1/Th2 Balance

Cadmium (Cd) is a type of toxic substance, which widely exists in nature. However, the effect of Cd exposure on the toxicity of swine lungs and its underlying mechanism involved have not yet been reported. In our study, we divided swine into two groups, including a control group (C group) and Cd-exposed group. Swine in the C group were fed a basic diet, whereas swine in the Cd group were fed a 20 mg Cd/kg diet. Immunofluorescence, qRT-PCR, western blot analysis, and H&E staining were performed to detect necroptosis-related indicators. Our results found that after Cd exposure, Th1/Th2 imbalance occurred, miR-181-5p was down-regulated, TNF-α expression was increased, and the NF-κB/NLRP3 and JAK/STAT pathways and RIPK1/RIPK3/MLKL axis were activated. Furthermore, histopathological examination showed necrosis in swine lung after Cd exposure. Together, the above-mentioned results indicate that subacute Cd exposure is closely linked with necroptosis in swine lung. Our study provided evidence that Cd may act through miR-181-5p/TNF-α to induce necroptosis in swine lung. The findings of this study supplement the toxicological study of Cd and provide a reference for comparative medicine.

Multimodal Identification by Transcriptomics and Multiscale Bioassays of Active Components in Xuanfeibaidu Formula to Suppress Macrophage-Mediated Immune Response

Xuanfeibaidu Formula (XFBD) is a Chinese medicine used in the clinical treatment of coronavirus disease 2019 (COVID-19) patients. Although XFBD has exhibited significant therapeutic efficacy in clinical practice, its underlying pharmacological mechanism remains unclear. Here, we combine a comprehensive research approach that includes network pharmacology, transcriptomics, and bioassays in multiple model systems to investigate the pharmacological mechanism of XFBD and its bioactive substances. High-resolution mass spectrometry was combined with molecular networking to profile the major active substances in XFBD. A total of 104 compounds were identified or tentatively characterized, including flavonoids, terpenes, carboxylic acids, and other types of constituents. Based on the chemical composition of XFBD, a network pharmacology-based analysis identified inflammation-related pathways as primary targets. Thus, we examined the anti-inflammation activity of XFBD in a lipopolysaccharide-induced acute inflammation mice model. XFBD significantly alleviated pulmonary inflammation and decreased the level of serum proinflammatory cytokines. Transcriptomic profiling suggested that genes related to macrophage function were differently expressed after XFBD treatment. Consequently, the effects of XFBD on macrophage activation and mobilization were investigated in a macrophage cell line and a zebrafish wounding model. XFBD exerts strong inhibitory effects on both macrophage activation and migration. Moreover, through multimodal screening, we further identified the major components and compounds from the different herbs of XFBD that mediate its anti-inflammation function. Active components from XFBD, including Polygoni cuspidati Rhizoma, Phragmitis Rhizoma, and Citri grandis Exocarpium rubrum, were then found to strongly downregulate macrophage activation, and polydatin, isoliquiritin, and acteoside were identified as active compounds. Components of Artemisiae annuae Herba and Ephedrae Herba were found to substantially inhibit endogenous macrophage migration, while the presence of ephedrine, atractylenolide I, and kaempferol was attributed to these effects. In summary, our study explores the pharmacological mechanism and effective components of XFBD in inflammation regulation via multimodal approaches, and thereby provides a biological illustration of the clinical efficacy of XFBD.

Role of macrophage scavenger receptor MSR1 in the progression of non-alcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease (NAFLD), and the dysregulation of lipid metabolism and oxidative stress are the typical features. Subsequent dyslipidemia and oxygen radical production may render the formation of modified lipids. Macrophage scavenger receptor 1 (MSR1) is responsible for the uptake of modified lipoprotein and is one of the key molecules in atherosclerosis. However, the unrestricted uptake of modified lipoproteins by MSR1 and the formation of cholesterol-rich foamy macrophages also can be observed in NASH patients and mouse models. In this review, we highlight the dysregulation of lipid metabolism and oxidative stress in NASH, the alteration of MSR1 expression in physiological and pathological conditions, the formation of modified lipoproteins, and the role of MSR1 on macrophage foaming and NASH development and progression.

Advances in the research of the role of macrophage/microglia polarization-mediated inflammatory response in spinal cord injury

It is often difficult to regain neurological function following spinal cord injury (SCI). Neuroinflammation is thought to be responsible for this failure. Regulating the inflammatory response post-SCI may contribute to the recovery of neurological function. Over the past few decades, studies have found that macrophages/microglia are one of the primary effector cells in the inflammatory response following SCI. Growing evidence has documented that macrophages/microglia are plastic cells that can polarize in response to microenvironmental signals into M1 and M2 macrophages/microglia. M1 produces pro-inflammatory cytokines to induce inflammation and worsen tissue damage, while M2 has anti-inflammatory activities in wound healing and tissue regeneration. Recent studies have indicated that the transition from the M1 to the M2 phenotype of macrophage/microglia supports the regression of inflammation and tissue repair. Here, we will review the role of the inflammatory response and macrophages/microglia in SCI and repair. In addition, we will discuss potential molecular mechanisms that induce macrophage/microglia polarization, with emphasis on neuroprotective therapies that modulate macrophage/microglia polarization, which will provide new insights into therapeutic strategies for SCI.

Small Tweaks, Major Changes: Post-Translational Modifications That Occur within M2 Macrophages in the Tumor Microenvironment

The majority of proteins are subjected to post-translational modifications (PTMs), regardless of whether they occur in or after biosynthesis of the protein. Capable of altering the physical and chemical properties and functions of proteins, PTMs are thus crucial. By fostering the proliferation, migration, and invasion of cancer cells with which they communicate in the tumor microenvironment (TME), M2 macrophages have emerged as key cellular players in the TME. Furthermore, growing evidence illustrates that PTMs can occur in M2 macrophages as well, possibly participating in molding the multifaceted characteristics and physiological behaviors in the TME. Hence, there is a need to review the PTMs that have been reported to occur within M2 macrophages. Although there are several reviews available regarding the roles of M2 macrophages, the majority of these reviews overlooked PTMs occurring within M2 macrophages. Considering this, in this review, we provide a review focusing on the advancement of PTMs that have been reported to take place within M2 macrophages, mainly in the TME, to better understand the performance of M2 macrophages in the tumor microenvironment. Incidentally, we also briefly cover the advances in developing inhibitors that target PTMs and the application of artificial intelligence (AI) in the prediction and analysis of PTMs at the end of the review.

Macrophage Phenotypes and Gene Expression Patterns Are Unique in Naturally Occurring Metabolically Healthy Obesity

Obesity impacts 650 million individuals globally, often co-occurring with metabolic syndrome. Though many obese individuals experience metabolic abnormalities (metabolically unhealthy obese [MUO]), ~30% do not (metabolically healthy obese [MHO]). Conversely, >10% of lean individuals are metabolically unhealthy (MUL). To evaluate the physiologic drivers of these phenotypes, a 44-animal African green monkey cohort was selected using metabolic syndrome risk criteria to represent these four clinically defined health groups. Body composition imaging and subcutaneous adipose tissue (SQ AT) biopsies were collected. Differences in adipocyte size, macrophage subtype distribution, gene expression, vascularity and fibrosis were analyzed using digital immunohistopathology, unbiased RNA-seq, endothelial CD31, and Masson’s trichrome staining, respectively. MHO AT demonstrated significant increases in M2 macrophages (p = 0.02) and upregulation of fatty acid oxidation-related terms and transcripts, including FABP7 (p = 0.01). MUO AT demonstrated downregulation of these factors and co-occurring upregulation of immune responses. These changes occurred without differences in AT distributions, adipocyte size, AT endothelial cells, collagen I deposition, or circulating cytokine levels. Without unhealthy diet consumption, healthy obesity is defined by an increased SQ AT M2/M1 macrophage ratio and lipid handling gene expression. We highlight M2 macrophages and fatty acid oxidation as targets for improving metabolic health with obesity.

The role of macrophage scavenger receptor 1 (MSR1) in inflammatory disorders and cancer

Macrophage scavenger receptor 1 (MSR1), also named CD204, holds key inflammatory roles in multiple pathophysiologic processes. Present primarily on the surface of various types of macrophage, this receptor variably affects processes such as atherosclerosis, innate and adaptive immunity, lung and liver disease, and more recently, cancer. As highlighted throughout this review, the role of MSR1 is often dichotomous, being either host protective or detrimental to the pathogenesis of disease. We will discuss the role of MSR1 in health and disease with a focus on the molecular mechanisms influencing MSR1 expression, how altered expression affects disease process and macrophage function, the limited cell signalling pathways discovered thus far, the emerging role of MSR1 in tumour associated macrophages as well as the therapeutic potential of targeting MSR1.

SEC5 is involved in M2 polarization of macrophages via the STAT6 pathway, and its dysfunction in decidual macrophages is associated with recurrent spontaneous abortion

Decidual macrophages (dMϕs) play critical roles in the establishment of microhomeostasis at the maternal-fetal interface during pregnancy. Impaired macrophage polarization during early pregnancy is associated with recurrent spontaneous abortion (RSA). In the present study, the SEC5 expression level was found to be significantly decreased in primary dMϕs of patients with RSA, and downregulation of SEC5 expression inhibited M2 polarization and STAT6 phosphorylation, whereas SEC5 overexpression in the Mϕs promoted M2 polarization and STAT6 phosphorylation in vitro. We subsequently found that SEC5 interacted with STAT6 in THP-1-derived Mϕs. The abundance of phosphorylated STAT6 (pSTAT6) protein was obviously increased, with a predominant distribution in the nucleus, after M2 polarization of Mϕs, and SEC5 protein was colocalized with pSTAT6. Moreover, a significantly reduced pSTAT6 expression level was observed in the dMϕs of patients with RSA. M2 polarization of Mϕs showed a stimulatory effect on the proliferation and invasion of human extravillous trophoblasts (EVTs) in vitro, and downregulation of SEC5 expression in Mϕs effectively reversed this effect. In a mouse model of LPS-induced early pregnancy loss, the uterine SEC5 expression level and the number of M2-Mϕs at the maternal-fetal interface were significantly reduced. More interestingly, heterozygous SEC5-deficient (SEC5^−/+) pregnant mice were more sensitive to LPS-induced pregnancy loss. Taken together, these data indicate that SEC5 participates in the regulation of M2 polarization of Mϕs by interacting with STAT6 and that decreased SEC5 expression inhibits the M2 polarization of dMϕs and results in early pregnancy loss by interfering with the physical activities of EVTs and immunotolerance at the maternal-fetal interface.

Role of K63-linked ubiquitination in cancer

Ubiquitination is a critical type of post-translational modifications, of which K63-linked ubiquitination regulates interaction, translocation, and activation of proteins. In recent years, emerging evidence suggest involvement of K63-linked ubiquitination in multiple signaling pathways and various human diseases including cancer. Increasing number of studies indicated that K63-linked ubiquitination controls initiation, development, invasion, metastasis, and therapy of diverse cancers. Here, we summarized molecular mechanisms of K63-linked ubiquitination dictating different biological activities of tumor and highlighted novel opportunities for future therapy targeting certain regulation of K63-linked ubiquitination in tumor.

Soluble CD83 improves and accelerates wound healing by the induction of pro-resolving macrophages

To facilitate the recovery process of chronic and hard-to-heal wounds novel pro-resolving treatment options are urgently needed. We investigated the pro-regenerative properties of soluble CD83 (sCD83) on cutaneous wound healing, where sCD83 accelerated wound healing not only after systemic but also after topical application, which is of high therapeutic interest. Cytokine profile analyses revealed an initial upregulation of inflammatory mediators such as TNFα and IL-1β, followed by a switch towards pro-resolving factors, including YM-1 and IL-10, both expressed by tissue repair macrophages. These cells are known to mediate resolution of inflammation and stimulate wound healing processes by secretion of growth factors such as epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF), which promote vascularization as well as fibroblast and keratinocyte differentiation. In conclusion, we have found strong wound healing capacities of sCD83 beyond the previously described role in transplantation and autoimmunity. This makes sCD83 a promising candidate for the treatment of chronic- and hard-to-heal wounds.

MSR1 characterized by chromatin accessibility mediates M2 macrophage polarization to promote gastric cancer progression

BACKGROUND

M2 macrophages play an important role in gastric cancer progression and metastasis, but the underlying tumor-promoting mechanisms are largely unknown.

METHODS

The TCIA database was used to identify the infiltration profile of macrophages. Integrated ATAC-seq, RNA-seq, and single-cell RNA sequencing (scRNA-seq) data from GC samples were used for the analysis. Using ATAC-seq profiles and RNA-seq datasets, combined with cox univariate survival analysis, we identified prognosis-related differentially expressed genes (DEGs) with chromatin accessibility, which were identified as hub genes. The CIBERSORTx algorithm was utilized to estimate the relative infiltration level of M2 macrophages, and Pearson correlation analysis was performed to investigate the relationship between hub genes and M2 macrophages. Multidimensional database validations were carried out to avoid biases. The expression level and function of hub genes in the clusters of macrophages were evaluated by using scRNA-seq data. The role of hub genes in the alternative activation of macrophages and gastric cancer malignant behaviors, as well as their potential regulatory mechanism in gastric cancer progression, were further explored.

RESULTS

17,334 genes were acquired with chromatin accessibility in promoter regions by ATAC-seq. 2,714 genes were identified with both chromatin accessibility and differential expression based on the gene expression profiles (RNA-seq). By performing Cox univariate survival analysis, 171 survival-related DEGs with chromatin accessibility were identified as hub genes. Through the CIBERSORTx algorithm and Pearson correlation analysis, the gene MSR1 most associated with M2 macrophages was screened out. According to the scRNA-seq analysis, MSR1 was highly expressed in the clusters of macrophages and may be involved in regulating M2 macrophage polarization. In vitro experiments confirmed that M2 macrophage polarization and its induced malignant behavior of gastric cancer cells were inhibited by knockdown of MSR1. Furthermore, MSR1 mediated M2 macrophage polarization by regulating arginine and proline metabolism, thereby activating the AMPK/mTOR pathway to promote gastric cancer progression.

CONCLUSION

We identified a gene-MSR1-characterized by chromatin accessibility, associated with poor prognosis in gastric cancer. This gene dictates the progression of gastric cancer by facilitating M2 macrophage polarization.

Ameliorating Inflammation in Insulin-resistant Rat Adipose Tissue with Abdominal Massage Regulates SIRT1/NF-κB Signaling

It was the aim of this study to determine whether abdominal massage reverses high-fat diet-induced insulin resistance compared with RSV treatment. A total of sixty male Sprague-Dawley rats were randomly placed in one of four groups:the non-fat diet (NFD), the high-fat diet (HFD), the HFD with abdominal massage (HFD+ AM), and the HFD plus resveratrol (HFD+ RSV). For eight weeks, rats were fed high-fat diets to create insulin resistance, followed by six weeks of either AM or RSV. Molecular mechanisms of adipogenesis and cytokine production in rats with high-fat diets were investigated. The model rat adipose tissue showed significant improvements in obesity, glucose intolerance, and the accumulation of lipid in the body [the total cholesterol level (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)], metabolic effects of glucose [The fasting blood glucose (FBG), Fasting insulin levels (FINS)], inflammatory status [interleukin-6 (IL-6) and tumor necrosis factor (TNF)-α, C-reactive protein (CRP)], and macrophage polarization after AM or RSV treatment. Further, AM increased SIRT1/NF-κB signaling in rat adipose tissue. Accordingly, in rat adipose tissue, our results indicate that AM regulates the secretion of proinflammatory cytokines, blood sugar levels, and related signaling pathways, contributing to improvement of IR, which may serves as a new therapeutic approach for the treatment for IR.

Neobavaisoflavone ameliorates LPS-induced RAW264.7 cell inflammations by suppressing the activation of NF-κB and MAPKs signaling pathways

Objectives

Neobavaisoflavone (NBIF) is an isoflavone isolated from Psoralea corylifolia L. It can effectively regulate the redox state as a natural anti-oxidant and show some anti-inflammatory activity. However, its molecular mechanism is poorly studied. In this study, RAW264.7 cells were treated with lipopolysaccharide (LPS) to investigate the anti-inflammatory activity and potential NBIF mechanism.

Materials and Methods

RAW264.7 cells were treated with LPS (62.5 ng/ml) and exposed to different concentrations of NBIF (0.01, 0.1, and 1 μM) for 24 hr. Inflammatory cytokines of RAW264.7 cells were measured by the Griess method, ELISA, and western blot. Phagocytosis of RAW264.7 macrophages was measured by FITC-dextran uptake assay. The phosphorylation protein expression levels of MAPKs (JNK, p38, and ERK), NF-κB p65, IκBα, and IκB kinase were analyzed by western blot. The results were analyzed using one-way ANOVA with Tukey's multiple comparison test.

Results

NBIF significantly inhibited NO and ROS production by down-regulation of iNOS and COX-2 protein expression. Additionally, the amount of release and protein levels of inflammation cytokines IL-6, IL-1β, and TNF-α were significantly decreased by NBIF. Moreover, FITC-dextran uptake assay by flow cytometry presented that NBIF significantly enhanced the phagocytic capacity of RAW264.7. Mechanistically, NBIF significantly down-regulated MAPK activation and inhibited the nuclear translocation of NF-κB p65.

Conclusion

The present study demonstrates that NBIF inhibited inflammation and enhanced the phagocytic capacity of RAW264.7 cell-related MAPKs and NF-κB signaling pathways induced by LPS. These findings suggest that NBIF may have clinical utility as an anti-inflammatory agent.

Crosstalk between macrophages and innate lymphoid cells (ILCs) in diseases

Innate lymphoid cells (ILCs) and macrophages are tissue-resident cells that play important roles in tissue-immune homeostasis and immune regulation. ILCs are mainly distributed on the barrier surfaces of mammals to ensure immunity or tissue homeostasis following host, microbial, or environmental stimulation. Their complex relationships with different organs enable them to respond quickly to disturbances in environmental conditions and organ homeostasis, such as during infections and tissue damage. Gradually emerging evidence suggests that ILCs also play complex and diverse roles in macrophage development, homeostasis, polarization, inflammation, and viral infection. In turn, macrophages also determine the fate of ILCs to some extent, which indicates that network crossover between these interactions is a key determinant of the immune response. More work is needed to better define the crosstalk of ILCs with macrophages in different tissues and demonstrate how it is affected during inflammation and other diseases. Here, we summarize current research on the functional interactions between ILCs and macrophages and consider the potential therapeutic utility of these interactions for the benefit of human health.

Proteomic characterization of four subtypes of M2 macrophages derived from human THP-1 cells

Macrophages are widely distributed immune cells that contribute to tissue homeostasis. Human THP-1 cells have been widely used in various macrophage-associated studies, especially those involving pro-inflammatory M1 and anti-inflammatory M2 phenotypes. However, the molecular characterization of four M2 subtypes (M2a, M2b, M2c, and M2d) derived from THP-1 has not been fully investigated. In this study, we systematically analyzed the protein expression profiles of human THP-1-derived macrophages (M0, M1, M2a, M2b, M2c, and M2d) using quantitative proteomics approaches. The commonly and specially regulated proteins of the four M2 subtypes and their potential biological functions were further investigated. The results showed that M2a and M2b, and M2c and M2d have very similar protein expression profiles. These data could serve as an important resource for studies of macrophages using THP-1 cells, and provide a reference to distinguish different M2 subtypes in macrophage-associated diseases for subsequent clinical research.

Macrophage scavenger receptor 1 mediates lipid-induced inflammation in non-alcoholic fatty liver disease

BACKGROUND & AIMS

Obesity-associated inflammation is a key player in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the role of macrophage scavenger receptor 1 (MSR1, CD204) remains incompletely understood.

METHODS

A total of 170 NAFLD liver biopsies were processed for transcriptomic analysis and correlated with clinicopathological features. Msr1^-/- and wild-type mice were subjected to a 16-week high-fat and high-cholesterol diet. Mice and ex vivo human liver slices were treated with a monoclonal antibody against MSR1. Genetic susceptibility was assessed using genome-wide association study data from 1,483 patients with NAFLD and 430,101 participants of the UK Biobank.

RESULTS

MSR1 expression was associated with the occurrence of hepatic lipid-laden foamy macrophages and correlated with the degree of steatosis and steatohepatitis in patients with NAFLD. Mice lacking Msr1 were protected against diet-induced metabolic disorder, showing fewer hepatic foamy macrophages, less hepatic inflammation, improved dyslipidaemia and glucose tolerance, and altered hepatic lipid metabolism. Upon induction by saturated fatty acids, MSR1 induced a pro-inflammatory response via the JNK signalling pathway. In vitro blockade of the receptor prevented the accumulation of lipids in primary macrophages which inhibited the switch towards a pro-inflammatory phenotype and the release of cytokines such as TNF-ɑ. Targeting MSR1 using monoclonal antibody therapy in an obesity-associated NAFLD mouse model and human liver slices resulted in the prevention of foamy macrophage formation and inflammation. Moreover, we identified that rs41505344, a polymorphism in the upstream transcriptional region of MSR1, was associated with altered serum triglycerides and aspartate aminotransferase levels in a cohort of over 400,000 patients.

CONCLUSIONS

Taken together, our data suggest that MSR1 plays a critical role in lipid-induced inflammation and could thus be a potential therapeutic target for the treatment of NAFLD.

LAY SUMMARY

Non-alcoholic fatty liver disease (NAFLD) is a chronic disease primarily caused by excessive consumption of fat and sugar combined with a lack of exercise or a sedentary lifestyle. Herein, we show that the macrophage scavenger receptor MSR1, an innate immune receptor, mediates lipid uptake and accumulation in Kupffer cells, resulting in liver inflammation and thereby promoting the progression of NAFLD in humans and mice.

Sporothrix schenckii regulates macrophage inflammatory responses via the c-JUN-induced Dab2 transcription

Macrophages, which serve as a bridge between innate and adaptive immunity, play an important role in sporotrichosis. Sporothrix schenckii infections can produce immune responses such as macrophage polarization and inflammatory factor secretion. In the early stages of inflammation, the expression of DAB2 in macrophages is increased, which controls the secretion of inflammatory factors and affects the polarization of macrophages. However, the expressions and mechanisms of DAB2 in sporotrichosis are not clear. In this study, we examined the expression of DAB2 and its regulation of inflammatory factors under conditions of Sporothrix schenckii infection. Our results indicated that the Sporothrix schenckii infection increased the expression of DAB2 and revealed a mixed M1/M2-like type of gene expression in BMDMs with the inhibited Il6, Il1β and Arg1, and induced Tnfα, Il10 and Mgl1. The deficiency of Dab2 gene suspended the changes of cytokines. In addition, JNK activity in BMDMs was inhibited by Sporothrix schenckii infection, leading to an increase in c-JUN. We also identified c-JUN as a transcription factor for Dab2 through chromatin immunoprecipitation and luciferase reporter assays. In an in vivo mouse model, sporotrichosis induced skin lesions were accompanied with an upregulation of c-JUN and inhibition of JNK activity, which were in accord with findings from in vitro experiments. Taken together, these findings indicate that in the early stages of Sporothrix schenckii infection there is a promotion of DAB2 expression through the JNK/c-JUN pathway, effects which can then control the expression of inflammatory factors.

Disruption of USP9X in macrophages promotes foam cell formation and atherosclerosis

Subendothelial macrophage internalization of modified lipids and foam cell formation are hallmarks of atherosclerosis. Deubiquitinating enzymes (DUBs) are involved in various cellular activities; however, their role in foam cell formation is not fully understood. Here, using a loss-of-function lipid accumulation screening, we identified ubiquitin-specific peptidase 9 X-linked (USP9X) as a factor that suppressed lipid uptake in macrophages. We found that USP9X expression in lesional macrophages was reduced during atherosclerosis development in both humans and rodents. Atherosclerotic lesions from macrophage USP9X-deficient mice showed increased macrophage infiltration, lipid deposition, and necrotic core content than control apolipoprotein E–KO (Apoe^–/–) mice. Additionally, loss-of-function USP9X exacerbated lipid uptake, foam cell formation, and inflammatory responses in macrophages. Mechanistically, the class A1 scavenger receptor (SR-A1) was identified as a USP9X substrate that removed the K63 polyubiquitin chain at the K27 site. Genetic or pharmacological inhibition of USP9X increased SR-A1 cell surface internalization after binding of oxidized LDL (ox-LDL). The K27R mutation of SR-A1 dramatically attenuated basal and USP9X knockdown–induced ox-LDL uptake. Moreover, blocking binding of USP9X to SR-A1 with a cell-penetrating peptide exacerbated foam cell formation and atherosclerosis. In this study, we identified macrophage USP9X as a beneficial regulator of atherosclerosis and revealed the specific mechanisms for the development of potential therapeutic strategies for atherosclerosis.

Fatty acids derived from apoptotic chondrocytes fuel macrophages FAO through MSR1 for facilitating BMSCs osteogenic differentiation

The nonunion following a fracture is associated with severe patient morbidity and economic consequences. Currently, accumulating studies are focusing on the importance of macrophages during fracture repair. However, details regarding the process by which macrophages facilitate endochondral ossification (EO) are largely unknown. In this study, we present evidence that apoptotic chondrocytes (ACs) are not inert corpses awaiting removal, but positively modulate the osteoinductive ability of macrophages. In vivo experiments revealed that fatty acid (FA) metabolic processes up-regulated following EO. In vitro studies further uncovered that FAs derived from ACs are taken up by macrophages mainly through macrophage scavenger receptor 1 (MSR1). Then, our functional experiments confirmed that these exogenous FAs subsequently activate peroxisome proliferator-activated receptor α (PPARα), which further facilitates lipid droplets generation and fatty acid oxidation (FAO). Mechanistically, elevated FAO is involved in up-regulating the osteoinductive effect by generating BMP7 and NAD⁺/SIRT1/EZH2 axis epigenetically controls BMP7 expression in macrophages cultured with ACs culture medium. Our findings advanced the concept that ACs could promote bone regeneration by regulating metabolic and function reprogram in macrophages and identified macrophage MSR1 represents a valuable target for fracture treatments.

Gene-selective transcription promotes the inhibition of tissue reparative macrophages by TNF

Pro-inflammatory TNF is a highly gene-selective inhibitor of the gene expression program of tissue repair and wound healing macrophages.

Anti-TNF therapies are a core anti-inflammatory approach for chronic diseases such as rheumatoid arthritis and Crohn’s Disease. Previously, we and others found that TNF blocks the emergence and function of alternative-activated or M2 macrophages involved in wound healing and tissue-reparative functions. Conceivably, anti-TNF drugs could mediate their protective effects in part by an altered balance of macrophage activity. To understand the mechanistic basis of how TNF regulates tissue-reparative macrophages, we used RNAseq, scRNAseq, ATACseq, time-resolved phospho-proteomics, gene-specific approaches, metabolic analysis, and signaling pathway deconvolution. We found that TNF controls tissue-reparative macrophage gene expression in a highly gene-specific way, dependent on JNK signaling via the type 1 TNF receptor on specific populations of alternative-activated macrophages. We further determined that JNK signaling has a profound and broad effect on activated macrophage gene expression. Our findings suggest that TNF’s anti-M2 effects evolved to specifically modulate components of tissue and reparative M2 macrophages and TNF is therefore a context-specific modulator of M2 macrophages rather than a pan-M2 inhibitor.

Gene expression profiling suggests severe, extensive central centrifugal cicatricial alopecia may be both clinically and biologically distinct from limited disease subtypes

The natural history of central centrifugal cicatricial alopecia (CCCA) is widely variable. Some patients experience rapid progression to extensive, end-stage disease while others never approach extensive involvement over decades, suggesting heterogeneity in CCCA disease phenotype. To better characterize clinically severe disease in CCCA, tissue samples were obtained from the peripheral, hair bearing lesional scalp of women with clinically focal, limited, and extensive CCCA disease involvement. A microarray analysis was conducted to identify differential expression of genes previously identified to be preferentially expressed in the lesional scalp vs non-lesional scalp of CCCA patients. Clinically extensive, severe CCCA was characterized by increased expression of MMP9, SFRP4, and MSR1 when directly compared with focal and limited disease. These biomarkers correspond to dysregulated pathways of fibrosis, Wnt signaling, and macrophage-mediated inflammatory processes, respectively. These findings hold significance for both possible targets for future study of prognostic markers of disease severity and new potential therapeutic targets. In summary, this study suggests clinically extensive, severe CCCA may have a differential gene expression pattern in the lesional scalp of affected patients, in addition to its clinical distinction.

Scavenger Receptor A1 Signaling Pathways Affecting Macrophage Functions in Innate and Adaptive Immunity

First discovered on macrophages by Goldstein and Brown in 1979, Scavenger Receptors have since been shown to participate in a diverse number of cell functions; equally diverse are their structures and the ligands they bind. Macrophage activation is crucial in the outcome of an immune response. SR-A1 is highly abundant on macrophages and recognizes both host- and microorganism-derived molecules that impact processes that are initiated, perpetuated, or modified. This review summarizes the involvement of SR-A1 in both inflammatory and anti-inflammatory responses, the multiple-ligand internalization mechanisms and the diversity of signaling pathways that impact macrophage function and activation. Engagement of SR-A1 results in the stimulation of differential signaling pathways and patterns of cytokine expression, kinetics, magnitude of response and activation status. SR-A1 plays essential roles in phagocytosis and efferocytosis, interacting with other receptors and promoting tolerance in response to apoptotic cell uptake. In cell adhesion, tissue remodeling, and cell migration, SR-A1 signals through different pathways engaging different cytoplasmic motifs. We describe the role of SR-A1 during innate and adaptive immune responses, such as participation in macrophage polarization and interaction with other innate receptors, as well as in antigen uptake, processing, and presentation, regulating T and B cell activation. The dichotomous contribution of SR-A1 on macrophage functions is discussed. A better understanding of the role SR-A1 plays through molecular mechanisms and crosstalk with other receptors may provide insights into developing novel therapeutic strategies to modulate immune responses and immunopathologies.

Lipid scavenging macrophages and inflammation

Macrophages are professional phagocytes, indispensable for maintenance of tissue homeostasis and integrity. Depending on their resident tissue, macrophages are exposed to highly diverse metabolic environments. Adapted to their niche, they can contribute to local metabolic turnover through metabolite uptake, conversion, storage and release. Disturbances in tissue homeostasis caused by infection, inflammation or damage dramatically alter the local milieu, impacting macrophage activation status and metabolism. In the case of persisting stimuli, defective macrophage responses ensue, which can promote tissue damage and disease. Especially relevant herein are disbalances in lipid rich environments, where macrophages are crucially involved in lipid uptake and turnover, preventing lipotoxicity. Lipid uptake is to a large extent facilitated by macrophage expressed scavenger receptors that are dynamically regulated and important in many metabolic diseases. Here, we review the receptors mediating lipid uptake and summarize recent findings on their role in health and disease. We further highlight the underlying pathways driving macrophage lipid acquisition and their impact on myeloid metabolic remodelling.

OLR1 is a prognostic factor and correlated with immune infiltration in breast cancer

Oxidized low-density lipoprotein receptor 1 (OLR1), a key receptor for oxidized low-density lipoprotein (ox-LDL), plays a crucial role in cancer and inflammatory disease. However, the correlation between OLR1 expression and immune infiltration in breast cancer (BC) remain unclear. In this study, we comprehensively analyzed the expression level of OLR1 in BC tissues and explore the prognostic importance of OLR1 using quantitative real-time PCR, immunohistochemical analysis and different databases. The significantly enriched KEGG and GO pathways were used to identify the potential biological function of OLR1 via LinkedOmics analysis. Furthermore, we detected the correlation between OLR1 expression and a variety of immune infiltrating cells via Tumor Immune Estimation Resource database and GEPIA database. Our study revealed that OLR1 upregulation was observed in BC tissues and correlated with worse clinical outcomes and advanced clinicopathological factors. Meanwhile, OLR1 regulated various immunity-related pathways, especially the polarization of macrophages. Immunohistochemical analysis further confirmed the significant correlation between OLR1 expression and tumor infiltration of M2 macrophages as well as tumor-associated macrophages. OLR1 upregulation indicated poor prognosis in BC, possibly through inducing macrophage polarization and triggering immune evasion. Collectively, OLR1 may represent a potential therapeutic target for BC tailored therapy.

Proteome Profiling of PMJ2-R and Primary Peritoneal Macrophages

In vitro models are often used for studying macrophage functions, including the process of phagocytosis. The application of primary macrophages has limitations associated with the individual characteristics of animals, which can lead to insufficient standardization and higher variability of the obtained results. Immortalized cell lines do not have these disadvantages, but their responses to various signals can differ from those of the living organism. In the present study, a comparative proteomic analysis of immortalized PMJ2-R cell line and primary peritoneal macrophages isolated from C57BL/6 mice was performed. A total of 4005 proteins were identified, of which 797 were quantified. Obtained results indicate significant differences in the abundances of many proteins, including essential proteins associated with the process of phagocytosis, such as Elmo1, Gsn, Hspa8, Itgb1, Ncf2, Rac2, Rack1, Sirpa, Sod1, C3, and Msr1. These findings indicate that outcomes of studies utilizing PMJ2-R cells as a model of peritoneal macrophages should be carefully validated. All MS data are deposited in ProteomeXchange with the identifier PXD022133.

Baicalin attenuates LPS-induced alveolar type II epithelial cell A549 injury by attenuation of the FSTL1 signaling pathway via increasing miR-200b-3p expression

In China, baicalin is the main active component of Scutellaria baicalensis, which has been used in the treatment of inflammation-related diseases, such as inflammation-induced acute lung injury. However, its specific mechanism remains unclear. This study examined the protective effect of baicalin on LPS-induced inflammation injury of alveolar epithelial cell line A549 and explored its protective mechanism. Compared with the LPS-induced group, the proliferation inhibition rates of alveolar type II epithelial cell line A549 intervened by different concentrations of baicalin decreased significantly, as did the levels of inflammatory factors IL-6, IL-1β, prostaglandin 2 and TNF-α in the supernatant. The expression levels of inflammatory proteins inducible NO synthase (iNOS), NF-κB65, phosphorylated ERK (p-ERK1/2), and phosphorylated c-Jun N-terminal kinase (p-JNK1) significantly decreased, as did the protein expression of follistatin-like protein 1 (FSTL1). In contrast, expression of miR-200b-3p significantly increased in a dose-dependent manner. These results suggested that baicalin could significantly inhibit the expression of inflammation-related proteins and improve LPS-induced inflammatory injury in alveolar type II epithelial cells. The mechanism may be related to the inhibition of ERK/JNK inflammatory pathway activation by increasing the expression of miR-200b-3p. Thus, FSTL1 is the regulatory target of miR-200b-3p.

L-theanine inhibits foam cell formation via promoting the scavenger receptor A degradation

Atherosclerosis is one of the most common cardiovascular diseases with highly mortality worldwide. The formation of foam cell plays an important role in the early stage of atherosclerosis pathogenesis. L-theanine is the most abundant free amino acid in tea, which possesses anti-inflammatory, anti-tumor and anti-atherosclerosis effects. However, little is known about the effects of L-theanine on the foam cell formation. In our study, RAW264.7 cells and primary mouse peritoneal macrophages were exposed to oxidized low density lipoprotein (ox-LDL) for inducing foam cell formation. We found that L-theanine significantly impeded cholesterol accumulation in macrophages, while inhibiting the formation of foam cell. Our further experiments showed that L-theanine attenuated the cholesterol uptake of RAW264.7 cells and primary mouse peritoneal macrophages by reducing the protein level of macrophage scavenger receptor A (SR-A), but not the level of mRNA suggesting that L-theanine regulates scavenger receptor A at the translational rather than transcriptional level. The present results demonstrated that L-theanine obviously promoted the degradation of scavenger receptor A protein and scavenger receptor A was degraded by ubiquitination dependent manner. Collectively, our research indicates that L-theanine suppresses the formation of macrophage foam cell by promoting the ubiquitination dependent degradation of scavenger receptor A.

Involvement of IL-4, IL-13 and Their Receptors in Pancreatic Cancer

Interleukin (IL)-4 and IL-13 are known as pleiotropic Th2 cytokines with a wide range of biological properties and functions especially in immune responses. In addition, increasing activities have also been determined in oncogenesis and tumor progression of several malignancies. It is now generally accepted that IL-4 and IL-13 can exert effects on epithelial tumor cells through corresponding receptors. Type II IL-4 receptor (IL-4Rα/IL-13Rα1), predominantly expressed in non-hematopoietic cells, is identified to be the main target for both IL-4 and IL-13 in tumors. Moreover, IL-13 can also signal by binding to the IL-13Rα2 receptor. Structural similarity due to the use of the same receptor complex generated in response to IL-4/IL-13 results in overlapping but also distinct signaling pathways and functions. The aim of this review was to summarize knowledge about IL-4 and IL-13 and their receptors in pancreatic cancer in order understand the implication of IL-4 and IL-13 and their receptors for pancreatic tumorigenesis and progression and for developing possible new diagnostic and therapeutic targets.