Metallothionein 3 Controls the Phenotype and Metabolic Programming of Alternatively Activated Macrophages

Gut dysbiosis impacts the immune system and promotes prostate cancer

The gut microbiota is a system of microorganisms in the human gastrointestinal (GI) system, consisting of trillions of microorganisms residing in epithelial surfaces of the body. Gut microbiota are exposed to various external and internal factors and form a unique gut-associated immunity maintained through a balancing act among diverse groups of microorganisms. The role of microbiota in dysbiosis of the gut in aiding prostate cancer development has created an urgency for extending research toward comprehension and preventative measures. The gut microbiota varies among persons based on diet, race, genetic background, and geographic location. Bacteriome, mainly, has been linked to GI complications, metabolism, weight gain, and high blood sugar. Studies have shown that manipulating the microbiome (bacteriome, virome, and mycobiome) through the dietary intake of phytochemicals positively influences physical and emotional health, preventing and delaying diseases caused by microbiota. In this review, we discuss the wealth of knowledge about the GI tract and factors associated with dysbiosis-mediated compromised gut immunity. This review also focuses on the relationship of dysbiosis to prostate cancer, the impact of microbial metabolites short-chain fatty acids (SCFAs) on host health, and the phytochemicals improving health while inhibiting prostate cancer.

Demystifying the landscape of endometrial immune microenvironment in luteal-phase from cuprotosis: Implications for the mechanism and treatment of RPL

BACKGROUND

Adaptive changes in the endometrial immune microenvironment during the luteal phase are essential for pregnancy, and their abnormalities are associated with recurrent pregnancy loss (RPL). Nevertheless, the specific mechanism is still unknown. Cuprotosis, an innovatively discovered type of programmed cell death, provides us with a pioneering perspective to decipher the landscape of luteal-phase endometrial immune microenvironment in RPL. This study aimed to analyze the immune landscape of luteal-phase endometrial microenvironment in RPL and explore the association of cuprotosis with it through integrative bioinformatics analysis.

METHODS

The microarrays involving the luteal phase endometrial tissue of RPL were obtained from the GEO database. Differentially expressed genes (DEGs) of RPL were screened and key modules were detected by WGCNA. GO, KEGG, and GSEA immune enrichment analyses were performed on the DEGs in the most relevant modules to RPL. Then, the endometrial immune microenvironment landscape of RPL was analyzed, including immune infiltration analysis and correlation analysis between immune cells or immune functions. The interaction of cuprotosis-related genes (CRGs), the expression level between groups, the immune localization and their correlation with immune cells and immune function were analyzed. LASSO regression and Nomogram evaluated the diagnostic value of immune-related CRGS in RPL. Functional enrichment analysis was performed on the RPL signature CRGs. And RPL samples were grouped according to the expression of 7 RPL signature CRGs through unsupervised clustering analysis. After that, we analyzed the expression level of CRGs and immune infiltration, as well as performed immune function enrichment analysis in subtypes. In addition, we also screened potential drugs that might act on CRGs to improve the pathological mechanism of RPL.

RESULTS

In this study, we uncovered that DEGs and genes in key modules derived from weighted gene co-expression network analysis (WGCNA) were involved in immune regulation. And the immune infiltration landscape of RPL was significantly different from healthy controls. Furthermore, six hub genes were screened from CRGs based on Cytohubba, and their expression profilings were verified in RPL and normal mouse samples. Besides, seven CRGs closely associated with the immune regulation of RPL were identified by Spearman correlation analysis, including SLC31A1, LIAS, DLD, DLAT, DBT, ATP7B, and ATP7A, named as immune-related CRGs. Furthermore, three subgroups clustered according to these seven genes showed significant differences in immune landscape, suggesting a remarkable effect of CRGs on immune regulation. Last but not least, we analyzed the regulation network of transcription factors, miRNAs, and CRGs, and screened potential compounds for the treatment of RPL by targeting CRGs.

CONCLUSIONS

The abnormal endometrial immune microenvironment in the luteal phase was associated with the pathomechanism of RPL, and cuprotosis was closely involved in the immune microenvironment in the luteal phase endometrium of RPL. Collectively, this study revealed the potential contribution of CRGs to the pathogenesis of RPL, providing a novel breakthroughs in insights into the pathogenesis, diagnosis, and treatment of RPL.

Inorganic Phosphate as "Bioenergetic Messenger" Triggers M2-Type Macrophage Polarization

The effects of calcium phosphate (CaP) materials on macrophage polarization state vary with their physicochemical properties. The study aims to elucidate the impact of phosphate ion-mediated energy metabolism on M2 macrophage polarization and the corresponding regulatory mechanism. The phosphate ions released from CaP ceramic as bioenergetic factor is identified; its concentration is closely associated with the polarized state. After being taken up by the sodium-dependent phosphate transporter 1, extracellular phosphate ions produce energy via oxidative phosphorylation by facilitating tricarboxylic acid flux, thereby contributing to M2 macrophage polarization. Further mechanistic analysis reveals that the elevation of the bioenergetic basis can drive macrophage M2 polarization via the AMP-activated protein kinase-mammalian target of rapamycin (AMPK-mTOR) axis. Another regulatory effect is that of the adenosine triphosphate (ATP), a signaling molecule. Intracellular ATP is released into the extracellular space and degraded to adenosine, which serves as a signaling molecule through the A2b adenosine receptor to activate the cyclic adenosine monophosphate (cAMP) pathway, thereby promoting M2 macrophage polarization. Overall, these findings may transform the existing knowledge on cell metabolism and energy homeostasis from bystanders to pivotal factors guiding M2 macrophage polarization and have implications for the future design of biomimetic CaP scaffolds.

Metabolic predictors of response to immune checkpoint blockade therapy

Metabolism of immune cells in the tumor microenvironment (TME) plays a critical role in cancer patient response to immune checkpoint inhibitors (ICI). Yet, a metabolic characterization of immune cells in the TME of patients treated with ICI is lacking. To bridge this gap we performed a semi-supervised analysis of ∼1700 metabolic genes using single-cell RNA-seq data of > 1 million immune cells from ∼230 samples of cancer patients treated with ICI. When clustering cells based on their metabolic gene expression, we found that similar immunological cellular states are found in different metabolic states. Most importantly, we found metabolic states that are significantly associated with patient response. We then built a metabolic predictor based on a dozen gene signature, which significantly differentiates between responding and non-responding patients across different cancer types (AUC = 0.8-0.92). Taken together, our results demonstrate the power of metabolism in predicting patient response to ICI.

Galactomannan-graft-poly(methyl methacrylate) nanoparticles induce an anti-inflammatory phenotype in human macrophages

Macrophages are immune cells that can be activated into either pro-inflammatory M1 or anti-inflammatory M2 phenotypes. Attempts to modulate macrophage phenotype using drugs have been limited by targeting issues and systemic toxicity. This study investigates the effect of drug-free self-assembled hydrolyzed galactomannan-poly(methyl methacrylate) (hGM-g-PMMA) nanoparticles on the activation of the human monocyte-derived macrophage THP-1 cell line. Nanoparticles are cell compatible and are taken up by macrophages. RNA-sequencing analysis of cells exposed to NPs reveal the upregulation of seven metallothionein genes. Additionally, the secretion of pro-inflammatory and anti-inflammatory cytokines upon exposure of unpolarized macrophages and M1-like cells obtained by activation with lipopolysaccharide + interferon-γ to the NPs is reduced and increased, respectively. Finally, nanoparticle-treated macrophages promote fibroblast migration in vitro. Overall, results demonstrate that hGM-g-PMMA nanoparticles induce the release of anti-inflammatory cytokines by THP-1 macrophages, which could pave the way for their application in the therapy of different inflammatory conditions, especially by local delivery.

Immunometabolism changes in fibrosis: from mechanisms to therapeutic strategies

Immune cells are essential for initiating and developing the fibrotic process by releasing cytokines and growth factors that activate fibroblasts and promote extracellular matrix deposition. Immunometabolism describes how metabolic alterations affect the function of immune cells and how inflammation and immune responses regulate systemic metabolism. The disturbed immune cell function and their interactions with other cells in the tissue microenvironment lead to the origin and advancement of fibrosis. Understanding the dysregulated metabolic alterations and interactions between fibroblasts and the immune cells is critical for providing new therapeutic targets for fibrosis. This review provides an overview of recent advances in the pathophysiology of fibrosis from the immunometabolism aspect, highlighting the altered metabolic pathways in critical immune cell populations and the impact of inflammation on fibroblast metabolism during the development of fibrosis. We also discuss how this knowledge could be leveraged to develop novel therapeutic strategies for treating fibrotic diseases.

Hypoxia inducible factor-1α is an important regulator of macrophage biology

Hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcription factor composed of the α and β subunits, regulates cellular adaptive responses to hypoxia. Macrophages, which are derived from monocytes, function as antigen-presenting cells that activate various immune responses. HIF-1α regulates the immune response, viability, migration, phenotypic plasticity, and metabolism of macrophages. Specifically, macrophage-derived HIF-1α can prevent excessive pro-inflammatory responses by attenuating the transcriptional activity of nuclear factor-kappa B in vivo and in vitro. HIF-1α modulates macrophage migration by inducing the release of various chemokines and providing necessary energy. HIF-1α promotes macrophage M1 polarization by targeting glucose metabolism. Additionally, HIF-1α induces the upregulation of glycolysis-related enzymes and intermediates of the tricarboxylic acid cycle and pentose phosphate pathway. HIF-1α promotes macrophage apoptosis, necroptosis and reduces autophagy. The current review highlights the mechanisms associated with the regulation of HIF-1α stabilization in macrophages as well as the role of HIF-1α in modulating the physiological functions of macrophages.

Gene expression changes in therapeutic ultrasound-treated venous leg ulcers

Introduction

Low-frequency, low-intensity ultrasound has been previously shown to promote healing of chronic wounds in humans, but mechanisms behind these effects are poorly understood. The purpose of this study was to evaluate gene expression differences in debrided human venous ulcer tissue from patients treated with low-frequency (20 kHz), low-intensity (100 mW/cm2) ultrasound compared to a sham treatment in an effort to better understand the potential biological mechanisms.

Methods

Debrided venous ulcer tissue was collected from 32 subjects one week after sham treatment or low-frequency, low-intensity ultrasound treatment. Of these samples, 7 samples (3 ultrasound treated and 4 sham treated) yielded sufficient quality total RNA for analysis by ultra-high multiplexed PCR (Ampliseq) and expression of more than 24,000 genes was analyzed. 477 genes were found to be significantly differentially expressed between the ultrasound and sham groups using cut-off values of p < 0.05 and fold change of 2.

Results and Discussion

The top differentially expressed genes included those involved in regulation of cell metabolism, proliferation, and immune cell signaling. Gene set enrichment analysis identified 20 significantly enriched gene sets from upregulated genes and 4 significantly enriched gene sets from downregulated genes. Most of the enriched gene sets from upregulated genes were related to cell-cell signaling pathways. The most significantly enriched gene set from downregulated genes was the inflammatory response gene set. These findings show that therapeutic ultrasound influences cellular behavior in chronic wounds as early as 1 week after application. Considering the well-known role of chronic inflammation in impairing wound healing in chronic wounds, these results suggest that a downregulation of inflammatory genes is a possible biological mechanism of ultrasound-mediated venous chronic wound healing. Such increased understanding may ultimately lead to the enhancement of ultrasound devices to accelerate chronic wound healing and increase patient quality of life.

Berberine promotes M2 macrophage polarisation through the IL-4-STAT6 signalling pathway in ulcerative colitis treatment

Aim

This study focusses on the anti-inflammatory and immune-modulatory roles of berberine (BBR) in ulcerative colitis (UC) treatment. Additionally, the underlying mechanisms of BBR were systematically explored.

Methods

A 3% (w/v) dextran sodium sulphate (DSS) solution was used for establishing the mice UC model. M2 macrophage polarisation was induced in RAW 264.7 cells using interleukin 4 (IL-4), whereas M1 macrophage polarisation was induced using lipopolysaccharide. Colon length, colon mucosa damage index (CMDI), and haematoxylin-eosin (HE) staining were used to evaluate colon damage induced by DSS. M1/M2 macrophages in the colon tissue were identified using immunofluorescence (IF) staining with CD86⁺ or CD163+. M1/M2 macrophages in the abdomen were examined using flow cytometry. An enzyme-linked immunosorbent assay was conducted to identify M1/M2 macrophage supernatant biomarkers in RAW 264.7 cells. Western blotting, immunohistochemical staining, and real-time PCR were performed to investigate the potential mechanisms of BBR for treating UC in vivo and in vitro.

Results

BBR was found to prolong colon length, ameliorate CMDI and alleviate the colon's pathological changes in UC mice. In DSS-induced UC mice, M1 macrophages predominated. BBR promoted M2 macrophages and suppressed M1 macrophages in the colon and abdomen of DSS-induced UC mice. Additionally, BBR significantly decreased M1-specific markers (IFN-γ and IL-1β) while increasing M2-specific markers (IL-10 and TGF-β) in the supernatants of RAW 264.7 cells. BBR upregulated the mRNA expression of IL-4, STAT6, and Chil3 while downregulating TNF-α, IFN-γ, and NOS2 expression in vivo. Moreover, BBR activated the downstream targets of the IL-4-STAT6 signalling pathway and enhanced the phosphorylation of STAT6 in vivo and in vitro to polarise M2 macrophage.

Conclusion

In UC mice, BBR suppressed M1 macrophages while promoting M2 macrophages. M1 macrophage suppression and M2 macrophage activation were strongly correlated with the anti-inflammatory and immune-modulating activities of BBR. BBR induced the polarisation of M2 macrophages by activating the IL-4-STAT6 signalling pathway, which contributed to its therapeutic efficacy against UC.

Apo-metallothionein-3 cooperatively forms tightly compact structures under physiological conditions

Metallothioneins (MTs) are essential mammalian metal chaperones. MT isoform 1 (MT1) is expressed in the kidneys and isoform 3 (MT3) is expressed in nervous tissue. For MTs, the solution-based NMR structure was determined for metal-bound MT1 and MT2, and only one X-ray diffraction structure on a crystallized mixed metal-bound MT2 has been reported. The structure of solution-based metalated MT3 is partially known using NMR methods; however, little is known about the fluxional de novo apo-MT3 because the structure cannot be determined by traditional methods. Here, we used cysteine modification coupled with electrospray ionization mass spectrometry, denaturing reactions with guanidinium chloride, stopped-flow methods measuring cysteine modification and metalation, and ion mobility mass spectrometry to reveal that apo-MT3 adopts a compact structure under physiological conditions and an extended structure under denaturing conditions, with no intermediates. Compared with apo-MT1, we found that this compact apo-MT3 binds to a cysteine modifier more cooperatively at equilibrium and 0.5 times the rate, providing quantitative evidence that many of the 20 cysteines of apo-MT3 are less accessible than those of apo-MT1. In addition, this compact apo-MT3 can be identified as a distinct population using ion mobility mass spectrometry. Furthermore, proposed structural models can be calculated using molecular dynamics methods. Collectively, these findings provide support for MT3 acting as a noninducible regulator of the nervous system compared with MT1 as an inducible scavenger of trace metals and toxic metals in the kidneys.

Pleural CD14+ monocytes/macrophages of healthy adolescents show a high expression of metallothionein family genes

Nowadays laparoscopic interventions enable the collection of resident macrophage populations out of the human cavities. We employed this technique to isolate pleural monocytes/macrophages from healthy young adults who underwent a correction of pectus excavatum. High quality CD14⁺ monocytes/macrophages (plMo/Mφ) were used for RNA-sequencing (RNA-seq) in comparison with human monocyte-derived macrophages (MDM) natural (MDM-0) or IL-4-polarized (MDM-IL4). Transcriptome analysis revealed 7166 and 7076 differentially expressed genes (DEGs) in plMo/Mφ relative to natural MDM-0 and polarized MDM-IL4, respectively. The gene set enrichment analysis, which was used to compare RNA-seq data from plMo/Mφ with single-cell (scRNA-seq) data online from human bronchial lavage macrophages, showed that plMo/Mφs are characterized by a high expression of genes belonging to the metallothionein (MT) family, and that the expression of these genes is significantly higher in plMo/Mφ than in MDM-0 or MDM-IL4. Our results provide additional insights on high MTs-expressing macrophage subsets, which seem to be present not only in bronchial lavage of healthy adults or in pleural exudates of lung cancer patients but also in pleural fluid of healthy young adults. Macrophage subsets expressing high MTs may have specific roles in lung defense, repair, and homeostasis, and require further investigations.

Metal binding and interdomain thermodynamics of mammalian metallothionein-3: enthalpically favoured Cu+ supplants entropically favoured Zn2+ to form Cu4 + clusters under physiological conditions

Metallothioneins (MTs) are a ubiquitous class of small metal-binding proteins involved in metal homeostasis and detoxification. While known for their high affinity for d¹⁰ metal ions, there is a surprising dearth of thermodynamic data on metals binding to MTs. In this study, Zn²⁺ and Cu⁺ binding to mammalian metallothionein-3 (MT-3) were quantified at pH 7.4 by isothermal titration calorimetry (ITC). Zn²⁺ binding was measured by chelation titrations of Zn₇MT-3, while Cu⁺ binding was measured by Zn²⁺ displacement from Zn₇MT-3 with competition from glutathione (GSH). Titrations in multiple buffers enabled a detailed analysis that yielded condition-independent values for the association constant (K) and the change in enthalpy (ΔH) and entropy (ΔS) for these metal ions binding to MT-3. Zn²⁺ was also chelated from the individual α and β domains of MT-3 to quantify the thermodynamics of inter-domain interactions in metal binding. Comparative titrations of Zn₇MT-2 with Cu⁺ revealed that both MT isoforms have similar Cu⁺ affinities and binding thermodynamics, indicating that ΔH and ΔS are determined primarily by the conserved Cys residues. Inductively coupled plasma mass spectrometry (ICP-MS) analysis and low temperature luminescence measurements of Cu-replete samples showed that both proteins form two Cu₄ ⁺-thiolate clusters when Cu⁺ displaces Zn²⁺ under physiological conditions. Comparison of the Zn²⁺ and Cu⁺ binding thermodynamics reveal that enthalpically-favoured Cu⁺, which forms Cu₄ ⁺-thiolate clusters, displaces the entropically-favoured Zn²⁺. These results provide a detailed thermodynamic analysis of d¹⁰ metal binding to these thiolate-rich proteins and quantitative support for, as well as molecular insight into, the role that MT-3 plays in the neuronal chemistry of copper.

Cirrhosis-associated immune dysfunction

The term cirrhosis-associated immune dysfunction (CAID) comprises the distinctive spectrum of immune alterations associated with the course of end-stage liver disease. Systemic inflammation and immune deficiency are the key components of CAID. Their severity is highly dynamic and progressive, paralleling cirrhosis stage. CAID involves two different immune phenotypes: the low-grade systemic inflammatory phenotype and the high-grade systemic inflammatory phenotype. The low-grade systemic inflammatory phenotype can be found in patients with compensated disease or clinical decompensation with no organ failure. In this phenotype, there is an exaggerated immune activation but the effector response is not markedly compromised. The high-grade systemic inflammatory phenotype is present in patients with acute-on-chronic liver failure, a clinical situation characterized by decompensation, organ failure and high short-term mortality. Along with high-grade inflammation, this CAID phenotype includes intense immune paralysis that critically increases the risk of infections and worsens prognosis. The intensity of CAID has important consequences on cirrhosis progression and correlates with the severity of liver insufficiency, bacterial translocation and organ failure. Therapies targeting the modulation of the dysfunctional immune response are currently being evaluated in preclinical and clinical studies.

Metallothionein 3-Zinc Axis Suppresses Caspase-11 Inflammasome Activation and Impairs Antibacterial Immunity

Non-canonical inflammasome activation by mouse caspase-11 (or human CASPASE-4/5) is crucial for the clearance of certain gram-negative bacterial infections, but can lead to severe inflammatory damage. Factors that promote non-canonical inflammasome activation are well recognized, but less is known about the mechanisms underlying its negative regulation. Herein, we identify that the caspase-11 inflammasome in mouse and human macrophages (Mϕ) is negatively controlled by the zinc (Zn2+) regulating protein, metallothionein 3 (MT3). Upon challenge with intracellular lipopolysaccharide (iLPS), Mϕ increased MT3 expression that curtailed the activation of caspase-11 and its downstream targets caspase-1 and interleukin (IL)-1β. Mechanistically, MT3 increased intramacrophage Zn2+ to downmodulate the TRIF-IRF3-STAT1 axis that is prerequisite for caspase-11 effector function. In vivo, MT3 suppressed activation of the caspase-11 inflammasome, while caspase-11 and MT3 synergized in impairing antibacterial immunity. The present study identifies an important yin-yang relationship between the non-canonical inflammasome and MT3 in controlling inflammation and immunity to gram-negative bacteria.

The impact of metal availability on immune function during infection

Nutrient transition metals are required cofactors for many proteins to perform functions necessary for life. As such, the concentration of nutrient metals is carefully maintained to retain critical biological processes while limiting toxicity. During infection, invading bacterial pathogens must acquire essential metals, such as zinc, manganese, iron, and copper, from the host to colonize and cause disease. To combat this, the host exploits the essentiality and toxicity of nutrient metals by producing factors that limit metal availability, thereby starving pathogens or accumulating metals in excess to intoxicate the pathogen in a process termed 'nutritional immunity'. As a result of inflammation, a heterogeneous environment containing both metal-replete and -deplete niches is created, in which nutrient metal availability may have an underappreciated role in regulating immune cell function during infection. How the host manipulates nutrient metal availability during infection, and the downstream effects that nutrient metals and metal-sequestering proteins have on immune cell function, are discussed in this review.

Zinc Deprivation as a Promising Approach for Combating Methicillin-Resistant Staphylococcus aureus: A Pilot Study

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a global health burden with an urgent need for antimicrobial agents. Studies have shown that host immune responses limit essential metals such as zinc during infection, leading to the limitation of bacterial virulence. Thus, the deprivation of zinc as an important co-factor for the activity of many S. aureus enzymes can be a potential antimicrobial approach. However, the effect of zinc deprivation on S. aureus and MRSA is not fully understood. Therefore, the current study aimed to dissect the effects of zinc deprivation on S. aureus hemolytic activity and biofilm formation through employing biochemical and genetic approaches to study the effect of zinc deprivation on S. aureus growth and virulence. Chemically defined media (CDM) with and without ZnCl2, was used to assess the effect of zinc deprivation on growth, biofilm formation, and hemolytic activity in methicillin-susceptible S. aureus (MSSA) RN6390 and MRSA N315 strains. Zinc deprivation decreased the growth of RN6390 and N315 S. aureus strains significantly by 1.5-2 folds, respectively compared to the zinc physiological range encountered by the bacteria in the human body (7-20 µM) (p < 0.05). Zinc deprivation significantly reduced biofilm formation by 1.5 folds compared to physiological levels (p < 0.05). Moreover, the hemolytic activity of RN6390 and N315 S. aureus strains was significantly decreased by 20 and 30 percent, respectively compared to physiological zinc levels (p < 0.05). Expression of biofilm-associated transcripts levels at late stage of biofilm formation (20 h) murein hydrolase activator A (cidA) and cidB were downregulated by 3 and 5 folds, respectively (p < 0.05) suggested an effect on extracellular DNA production. Expression of hemolysins-associated genes (hld, hlb, hla) was downregulated by 3, 5, and 10 folds, respectively, in absence of zinc (p < 0.001). Collectively the current study showed that zinc deprivation in vitro affected growth, biofilm formation, and hemolytic activity of S. aureus. Our in vitro findings suggested that zinc deprivation can be a potential supportive anti-biofilm formation and antihemolytic approach to contain MRSA topical infections.

A metabolic inhibitor arms macrophages to kill intracellular fungal pathogens by manipulating zinc homeostasis

Macrophages deploy numerous strategies to combat invasion by microbes. One tactic is to restrict acquisition of diverse nutrients, including trace metals, a process termed nutritional immunity. Intracellular pathogens adapt to a resource-poor environment by marshaling mechanisms to harvest nutrients. Carbon acquisition is crucial for pathogen survival; compounds that reduce availability are a potential strategy to control intracellular replication. Treatment of macrophages with the glucose analog 2-deoxy-D-glucose (2-DG) armed phagocytes to eliminate the intracellular fungal pathogen Histoplasma capsulatum in vitro and in vivo. Killing did not rely on altering access to carbon-containing molecules or changes in ATP, ER stress, or autophagy. Unexpectedly, 2-DG undermined import of exogenous zinc into macrophages, decreasing the quantity of cytosolic and phagosomal zinc. The fungus perished as a result of zinc starvation. This change in metal ingress was not ascribed to a defect in a single importer; rather, there was a collective impairment in transporter activity. This effect promoted the antifungal machinery of macrophages and expanded the complexity of 2-DG activities far beyond manipulating glycolysis. Mechanistic metabolic studies employing 2-DG will have to consider its effect on zinc transport. Our preclinical data support consideration of this agent as a possible adjunctive therapy for histoplasmosis.

Metabolic reprogramming of macrophages and its involvement in inflammatory diseases

Macrophages are critical effector cells of the innate immune system. The presence of microbes or the stimulation by inflammatory factors triggers the metabolic reprogramming of macrophages or macrophage polarization into two phenotypes: the classically activated macrophages (M1) displaying a pro-inflammatory phenotype and the alternatively activated macrophages (M2) having anti-inflammatory functions. The imbalance between the two phenotypes has been linked with various pathological states, such as fibrosis, hepatitis, colitis, and tumor progression. An avenue of potential therapeutic strategies based on macrophage polarization has emerged. Therefore, it is essential to understand the mechanisms of macrophage polarization. In this review, we focus on the macrophage polarization process and discuss the stimuli-dependent conversion into M1 and M2 phenotypes. We also present the metabolic patterns supporting their specific functions. The factors and signaling cascades involved in intra-class switching are also detailed. Finally, the role of macrophage polarization in disease progression is discussed.

Anti-arthritis effect of berberine associated with regulating energy metabolism of macrophages through AMPK/ HIF-1α pathway

Berberine (BBR) is the effective constituent of Cortex phellodendri and was characterized as an excellent anti-microbial agent with significant anti-inflammatory effects. Previously, we had demonstrated that BBR alleviated the inflammatory response in adjuvant-induced arthritis (AA) rats by regulating polarization of macrophages. However, the exact mechanics by which BBR regulates macrophage polarization remained unclear. Here, we showed that BBR treatment had little influence on total number of macrophages in joints of AA rats, but increased the proportion of M2 macrophages and decreased the proportion of M1 macrophages. Meanwhile, we found BBR up-regulated the expression of AMP-activated protein kinase phosphorylation (p-AMPK) and down-regulated the expression of Hypoxia inducible factor 1α (HIF-1α) in synovial macrophages of AA rats. In vitro, using LPS-stimulated peritoneal macrophages from normal rats, we also verified that pretreatment with BBR promoted transition from M1 to M2 by up-regulating the expression of p-AMPK and suppressing the expression of HIF-1α. Compound C (an AMPK inhibitor) could abrogate the inhibition of BBR on migration of macrophages. Glycolysis of M1 suppressed by BBR through decreasing lactate export, glucose consumption, and increasing intracellular ATP content, which was remarkably reversed by Compound C. These findings indicated that anti-arthritis effect of BBR is associated with regulating energy metabolism of macrophages through AMPK/HIF-1α pathway.

Comparative study of the effects of ziram and disulfiram on human monocyte-derived macrophage functions and polarization: involvement of zinc

Ziram, a zinc dithiocarbamate is widely used worldwide as a fungicide in agriculture. In order to investigate ziram-induced changes in macrophage functions and polarization, human monocytes-derived macrophages in culture were treated with ziram at 0.01-10 μmol.L^-1 for 4-24 h. To characterize zinc involvement in these changes, we also determined the effects of disulfiram alone (dithiocarbamate without zinc) or in co-incubation with ZnSO₄. We have shown that ziram and disulfiram at 0.01 μmol.L^-1 increased zymosan phagocytosis. In contrast, ziram at 10 μmol.L^-1 completely inhibited this phagocytic process, the oxidative burst triggered by zymosan and the production of TNF-α, IL-1β, IL-6, and CCL2 triggered by LPS. Disulfiram had the same effects on these macrophages functions only when combined with zinc (10 μmol.L^-1). In contrast, at 10 μmol.L^-1 ziram and zinc associated-disulfiram induced expression of several antioxidants genes HMOX1, SOD2, and catalase, which could suggest the induction of oxidative stress. This oxidative stress could be involved in the increase in late apoptosis induced by ziram (10 μmol.L^-1) and zinc associated-disulfiram. Concerning gene expression profiles of membrane markers of macrophage polarization, ziram at 10 μmol.L^-1 had two opposite effects. It inhibited the gene expression of M2 markers (CD36, CD163) in the same way as the disulfiram-zinc co-treatment. Conversely, ziram induced gene expression of other M2 markers CD209, CD11b, and CD16 in the same way as treatment with zinc alone. Disulfiram-zinc association had no significant effects on these markers. These results taken together show that ziram via zinc modulates macrophages to M2-like anti-inflammatory phenotype which is often associated with various diseases.

Type I Interferons Ameliorate Zinc Intoxication of Candida glabrata by Macrophages and Promote Fungal Immune Evasion

Host and fungal pathogens compete for metal ion acquisition during infectious processes, but molecular mechanisms remain largely unknown. Here, we show that type I interferons (IFNs-I) dysregulate zinc homeostasis in macrophages, which employ metallothionein-mediated zinc intoxication of pathogens as fungicidal response. However, Candida glabrata can escape immune surveillance by sequestering zinc into vacuoles. Interestingly, zinc-loading is inhibited by IFNs-I, because a Janus kinase 1 (JAK1)-dependent suppression of zinc homeostasis affects zinc distribution in macrophages as well as generation of reactive oxygen species (ROS). In addition, systemic fungal infections elicit IFN-I responses that suppress splenic zinc homeostasis, thereby altering macrophage zinc pools that otherwise exert fungicidal actions. Thus, IFN-I signaling inadvertently increases fungal fitness both in vitro and in vivo during fungal infections. Our data reveal an as yet unrecognized role for zinc intoxication in antifungal immunity and suggest that interfering with host zinc homeostasis may offer therapeutic options to treat invasive fungal infections.

Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Attenuate LPS-Induced ARDS by Modulating Macrophage Polarization Through Inhibiting Glycolysis in Macrophages

Macrophages play a key role in the development of sepsis-induced acute respiratory distress syndrome (ARDS). Recent evidence has proved that glycolysis plays an important role in regulating macrophage polarization through metabolic reprogramming. Bone marrow mesenchymal stem cells (BMSCs) can alleviate sepsis-induced lung injury and possess potent immunomodulatory and immunosuppressive properties via secreting exosomes. However, it is unknown whether BMSCs-derived exosomes exert their therapeutic effect against sepsis-induced lung injury by inhibiting glycolysis in macrophages. Therefore, the present study aimed to evaluate the anti-inflammatory effects of exosomes released from BMSCs on acute lung injury induced by lipopolysaccharide (LPS) in mice and explored the possible underlying mechanisms in vitro and in vivo. We found that BMSCs inhibited M1 polarization and promoted M2 polarization in MH-S cells (a murine alveolar macrophage cell line) by releasing exosomes. Further experiments showed that exosomes secreted by BMSCs modulated LPS-treated MH-S cells polarization by inhibiting cellular glycolysis. Moreover, our results showed that BMSCs-derived exosomes down-regulated the expression of several essential proteins of glycolysis via inhibition of hypoxia-inducible factor 1 (HIF-1)α. Finally, a model of LPS-induced ARDS in mice was established, we found that BMSCs-derived exosomes ameliorated the LPS-induced inflammation and lung pathological damage. Meanwhile, we found that intratracheal delivery of BMSCs-derived exosomes effectively down-regulated LPS-induced glycolysis in mice lung tissue. These findings reveal new mechanisms of BMSCs-derived exosomes in regulating macrophage polarization which may provide novel strategies for the prevention and treatment of LPS-induced ARDS.

In Situ Mannosylated Nanotrinity-Mediated Macrophage Remodeling Combats Candida albicans Infection

Deep Candida albicans infection is one of the major causes of death in immunosuppressed hosts. Remodeling macrophages to phenotype M1 can decrease fungus burden and facilitate combating C. albicans under an immunosuppressive state. In this study, a nanotrinity was exploited to direct fungicidal macrophage polarization by leveraging the regulation pathways in macrophage redifferentiation. Conventional chemotherapeutic imatinib, which can abrogate M2 macrophage polarization via "shutting off" the STAT6 phosphorylation pathway, was encapsulated in biodegradable polymeric nanoparticles. In house-customized dual functional mannosylated chitosan oligosaccharides were then coated on the surface of the imatinib-laden nanoparticles, and thus, a mannosylated nanotrinity was achieved with ternary functions for macrophage remodeling: (i) imatinib-blocked STAT6 phosphorylation pathway for decreasing M2 macrophage population; (ii) chitosan oligosaccharides-mediated TLR-4 pathway activation that could promote macrophage redifferentiation to M1 phenotype; (iii) mannose motif-enhanced macrophage targeting. After physiochemical characterization, regulatory effects of the mannosylated nanotrinity on macrophages and the anti-C. albicans efficacy were evaluated at the cellular level and animal level, respectively. The results demonstrated that our mannosylated nanotrinity could efficiently induce macrophage polarization toward the M1 phenotype, decrease M2 phenotype production, and markedly lessen fungus burden and increased the median survival time of mice infected with C. albicans. Therefore, the mannosylated nanotrinity developed in this study could significantly induce macrophage remodeling in situ by the two-pronged process, "turning on" M1 phenotype polarization meanwhile "shutting off" M2 phenotype polarization, and thus allowed to eradicate C. albicans infection.

Development of an Immune-Related Prognostic Signature in Breast Cancer

BACKGROUND

Although increased early detection, diagnosis and treatment have improved the outcome of breast cancer patients, prognosis estimation still poses challenges due to the disease heterogeneity. Accumulating data indicated an evident correlation between tumor immune microenvironment and clinical outcomes.

OBJECTIVE

To construct an immune-related signature that can estimate disease prognosis and patient survival in breast cancer.

METHODS

Gene expression profiles and clinical data of breast cancer patients were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, which were further divided into a training set (n = 499), a testing set (n = 234) and a Meta-validation set (n = 519). In the training set, immune-related genes were recognized using combination of gene expression data and ESTIMATE algorithm-derived immune scores. An immune-related prognostic signature was generated with LASSO Cox regression analysis. The prognostic value of the signature was validated in the testing set and the Meta-validation set.

RESULTS

A total of 991 immune-related genes were identified. Twelve genes with non-zero coefficients in LASSO analysis were used to construct an immune-related prognostic signature. The 12-gene signature significantly stratified patients into high and low immune risk groups in terms of overall survival independent of clinical and pathologic factors. The signature also significantly stratified overall survival in clinical defined groups, including stage I/II disease. Several biological processes, such as immune response, were enriched among genes in the immune-related signature. The percentage of M2 macrophage infiltration was significantly different between low and high immune risk groups. Time-dependent ROC curves indicated good performance of our signature in predicting the 1-, 3- and 5-year overall survival for patients from the full TCGA cohort. Furthermore, the composite signature derived by integrating immune-related signature with clinical factors, provided a more accurate estimation of survival relative to molecular signature alone.

CONCLUSION

We developed a 12-gene prognostic signature, providing novel insights into the identification of breast cancer with a high risk of death and assessment of the possibility of immunotherapy incorporation in personalized breast cancer management.