Metabolic influence on macrophage polarization and pathogenesis

Methotrexate loaded extracellular vesicles attenuate periodontitis by suppressing ACSL1 and promoting anti-inflammatory macrophage

Macrophages are crucial immune cells in periodontal tissues, which play key roles in both the destruction and repair of associated with periodontitis. Targeted modulation of macrophage function has emerged as a potentially effective approach to influence periodontitis progression. This study investigates the effects of methotrexate-loaded extracellular vesicles (MTX-EVs) on inflammatory macrophage polarization both in vivo and in vitro. In a murine periodontitis model, MTX-EVs inhibited alveolar bone resorption, suppressed pro-inflammatory macrophage activation, and promoted anti-inflammatory macrophages. Mechanistically, MTX-EVs reduced acyl-CoA synthetase-1 (ACSL1) expression, which was elevated during inflammation. Inhibition of ACSL1 with triacsin-C in macrophages suppressed the inflammatory phenotype through the promotion of the oxidative phosphorylation (OXPHOS). In contrast, MTX-EVs counteracted the effects of ACSL1 overexpression on macrophage polarization and metabolism. Our findings suggest that targeting ACSL1 via MTX-EVs represents a therapeutic strategy for modulating macrophage polarization and improving periodontitis treatment outcomes.

Immunogenic shift of arginine metabolism triggers systemic metabolic and immunological reprogramming to suppress HER2 + breast cancer

BACKGROUND

Arginine metabolism in tumors is often shunted into the pathway producing pro-tumor and immune suppressive polyamines (PAs), while downmodulating the alternative nitric oxide (NO) synthesis pathway. Aiming to correct arginine metabolism in tumors, arginine deprivation therapy and inhibitors of PA synthesis have been developed. Despite some therapeutic advantages, these approaches have often yielded severe side effects, making it necessary to explore an alternative strategy. We previously reported that supplementing sepiapterin (SEP), the endogenous precursor of tetrahydrobiopterin (BH4, the essential NO synthase cofactor), could correct arginine metabolism in tumor cells and tumor-associated macrophages (TAMs) and induce their metabolic and phenotypic reprogramming. We saw that oral SEP treatment effectively suppressed the growth of HER2-positive mammary tumors in animals. SEP also has no reported dose-dependent toxicity in clinical trials for metabolic disorders. In the present study, we tested our hypothesis that a long-term administration of SEP to individuals susceptible to HER2-positive mammary tumor would protect them against tumor occurrence.

METHODS

We administered SEP, in comparison to control DMSO, to MMTV-neu mice susceptible to HER2-positive mammary tumors for 8 months starting at their pre-pubertal stage. We monitored tumor onsets to determine the rate of tumor-free survival. After 8 months of treatment, we grouped animals into DMSO treatment with or without tumors and SEP treatment with or without tumors. We analyzed blood metabolites, PBMC, and bone marrow of DMSO vs. SEP treated animals.

RESULTS

We found that a long-term use of SEP in animals susceptible to HER2-positive mammary tumors effectively suppressed tumor occurrence. These SEP-treated animals had undergone reprogramming of the systemic metabolism and immunity, elevating total T cell counts in the circulation and bone marrow. Given that bone marrow-resident T cells are mostly memory T cells, it is plausible that chronic SEP treatment promoted memory T cell formation, leading to a potent tumor prevention.

CONCLUSIONS

These findings suggest the possible roles of the SEP/BH4/NO axis in promoting memory T cell formation and its potential therapeutic utility for preventing HER2-positive breast cancer.

Molecular Underpinnings of Brain Metastases

Brain metastases are the most commonly diagnosed type of central nervous system tumor, yet the mechanisms of their occurrence are still widely unknown. Lung cancer, breast cancer, and melanoma are the most common etiologies, but renal and colorectal cancers have also been described as metastasizing to the brain. Regardless of their origin, there are common mechanisms for progression to all types of brain metastases, such as the creation of a suitable tumor microenvironment in the brain, priming of tumor cells, adaptations to survive spreading in lymphatic and blood vessels, and development of mechanisms to penetrate the blood-brain barrier. However, there are complex genetic and molecular interactions that are specific to every type of primary tumor, making the understanding of the metastatic progression of tumors to the brain a challenging field of study. In this review, we aim to summarize current knowledge on the pathophysiology of brain metastases, from specific genetic characteristics of commonly metastatic tumors to the molecular and cellular mechanisms involved in progression to the central nervous system. We also briefly discuss current challenges in targeted therapies for brain metastases and how there is still a gap in knowledge that needs to be overcome to improve patient outcomes.

Nitric oxide and mitochondrial function in cardiovascular diseases

Nitric oxide (NO) has been highlighted as an important factor in cardiovascular system. As a signaling molecule in the cardiovascular system, NO can relax blood vessels, lower blood pressure, and prevent platelet aggregation. Mitochondria serve as a central hub for cellular metabolism and intracellular signaling, and their dysfunction can lead to a variety of diseases. Accumulating evidence suggests that NO can act as a regulator of mitochondria, affecting mitochondrial function and cellular activity, which in turn mediates the onset and progression of disease. However, there is a lack of comprehensive understanding of how NO regulates mitochondrial function in the cardiovascular system. This review aims to summarize the regulation of mitochondrial function by nitric oxide in cardiovascular related diseases, as well as the multifaceted and complex roles of NO in the cardiovascular system. Understanding the mechanism of NO mediated mitochondrial function can provide new insights for the prevention and treatment of cardiovascular diseases.

Konjac glucomannan exerts regulatory effects on macrophages and its applications in biomedical engineering

Konjac glucomannan (KGM) molecular chains contain a small amount of acetyl groups and a large number of hydroxyl groups, thereby exhibiting exceptional water retention and gel-forming properties. To meet diverse requirements, KGM undergoes modification processes such as oxidation, acetylation, grafting, and cationization, which reduce its viscosity, enhance its mechanical strength, and improve its water solubility. Researchers have found that KGM and its derivatives can regulate the polarization of macrophages, inducing their transformation into classically activated M1-type macrophages or alternatively activated M2-type macrophages, and even facilitating the interconversion between M1 and M2 phenotypes. Concurrently, the modulation of macrophage polarization states holds significant importance for chronic wound healing, inflammatory bowel disease (IBD), antitumor therapy, tissue engineering scaffolds, oral vaccines, pulmonary delivery, and probiotics. Therefore, KGM has the advantages of both immunomodulatory effects (biological activity) and gel-forming properties (physicochemical properties), giving it significant advantages in a variety of biomedical engineering applications.

Reprogramming of breast tumor-associated macrophages with modulation of arginine metabolism

HER2+ breast tumors have abundant immune-suppressive cells, including M2-type tumor-associated macrophages (TAMs). Although TAMs consist of the immune-stimulatory M1 type and immune-suppressive M2 type, the M1/M2-TAM ratio is reduced in immune-suppressive tumors, contributing to their immunotherapy refractoriness. M1- versus M2-TAM formation depends on differential arginine metabolism, where M1-TAMs convert arginine to nitric oxide (NO) and M2-TAMs convert arginine to polyamines (PAs). We hypothesize that such distinct arginine metabolism in M1- versus M2-TAMs is attributed to different availability of BH4 (NO synthase cofactor) and that its replenishment would reprogram M2-TAMs to M1-TAMs. Recently, we reported that sepiapterin (SEP), the endogenous BH4 precursor, elevates the expression of M1-TAM markers within HER2+ tumors. Here, we show that SEP restores BH4 levels in M2-like macrophages, which then redirects arginine metabolism to NO synthesis and converts M2 type to M1 type. The reprogrammed macrophages exhibit full-fledged capabilities of antigen presentation and induction of effector T cells to trigger immunogenic cell death of HER2+ cancer cells. This study substantiates the utility of SEP in the metabolic shift of the HER2+ breast tumor microenvironment as a novel immunotherapeutic strategy.

Immunogenic shift of arginine metabolism triggers systemic metabolic and immunological reprogramming to prevent HER2+ breast cancer

Arginine metabolism in tumors is often shunted into the pathway producing pro-tumor and immune suppressive polyamines (PAs), while downmodulating the alternative nitric oxide (NO) synthesis pathway. Aiming to correct arginine metabolism in tumors, arginine deprivation therapy and inhibitors of PA synthesis have been developed. Despite some therapeutic advantages, these approaches have often yielded severe side effects, making it necessary to explore an alternative strategy. We previously reported that supplementing SEP, the endogenous precursor of BH4 (the essential NO synthase cofactor), could correct arginine metabolism in tumor cells and tumor-associated macrophages (TAMs) and induce their metabolic and phenotypic reprogramming. We saw that oral SEP treatment effectively suppressed the growth of HER2-positive mammary tumors in animals. SEP also has no reported dose-dependent toxicity in clinical trials for metabolic disorders. In the present study, we report that a long-term use of SEP in animals susceptible to HER2-positive mammary tumors effectively prevented tumor occurrence. These SEP-treated animals had undergone reprogramming of the systemic metabolism and immunity, elevating total T cell counts in the circulation and bone marrow. Given that bone marrow-resident T cells are mostly memory T cells, it is plausible that chronic SEP treatment promoted memory T cell formation, leading to a potent tumor prevention. These findings suggest the possible roles of the SEP/BH4/NO axis in promoting memory T cell formation and its potential therapeutic utility for preventing HER2-positive breast cancer.

Monomethyl Branched-Chain Fatty Acids Suppress M1 Macrophage Polarization via FABP4/PPAR-γ Signaling Pathway

SCOPE

Monomethyl-branched chain fatty acids (mmBCFAs) are found in a variety of food sources and are of great interest due to their potent antiinflammatory properties. However, most of the current researches have concentrated on the relationship between mmBCFAs and intestinal inflammation, and there is a large gap in the biological mechanisms involved behind their antiinflammatory effects.

METHODS AND RESULTS

The present study examines the role of mmBCFAs in modulating macrophage polarization. The results demonstrate that iso-C16:0 significantly inhibits macrophages M1 proinflammatory polarization through regulating FABP4/PPAR-γ pathway. Proteomics and molecular biology experiments verify that metabolic reprogramming is involved in the inhibition of M1 macrophage, referring to the upregulation of fatty acid oxidation, TCA cycle, and oxidative phosphorylation, as well as downregulation of glycolytic flux.

CONCLUSION

In summary, this study offers a novel perspective on the antiinflammatory effects mediated by mmBCFAs.

Branched-chain amino acids supplementation induces insulin resistance and pro-inflammatory macrophage polarization via INFGR1/JAK1/STAT1 signal pathway

BACKGROUND

Obesity is a global epidemic, and the low-grade chronic inflammation of adipose tissue in obese individuals can lead to insulin resistance and type 2 diabetes. Adipose tissue macrophages (ATMs) are the main source of pro-inflammatory cytokines in adipose tissue, making them an important target for therapy. While branched-chain amino acids (BCAA) have been strongly linked to obesity and type 2 diabetes in humans, the relationship between BCAA catabolism and adipose tissue inflammation is unclear. This study aims to investigate whether disrupted BCAA catabolism influences the function of adipose tissue macrophages and the secretion of pro-inflammatory cytokines in adipose tissue, and to determine the underlying mechanism. This research will help us better understand the role of BCAA catabolism in adipose tissue inflammation, obesity, and type 2 diabetes.

METHODS

In vivo, we examined whether the BCAA catabolism in ATMs was altered in high-fat diet-induced obesity mice, and if BCAA supplementation would influence obesity, glucose tolerance, insulin sensitivity, adipose tissue inflammation and ATMs polarization in mice. In vitro, we isolated ATMs from standard chow and high BCAA-fed group mice, using RNA-sequencing to investigate the potential molecular pathway regulated by BCAA accumulation. Finally, we performed targeted gene silence experiment and used immunoblotting assays to verify our findings.

RESULTS

We found that BCAA catabolic enzymes in ATMs were influenced by high-fat diet induced obesity mice, which caused the accumulation of both BCAA and its downstream BCKA. BCAA supplementation will cause obesity and insulin resistance compared to standard chow (STC) group. And high BCAA diet will induce pro-inflammatory cytokines including Interlukin-1beta (IL-1β), Tumor Necrosis Factor alpha (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) secretion in adipose tissue as well as promoting ATMs M1 polarization (pro-inflammatory phenotype). Transcriptomic analysis revealed that a high BCAA diet would activate IFNGR1/JAK1/STAT1 pathway, and IFNGR1 specific silence can abolish the effect of BCAA supplementation-induced inflammation and ATMs M1 polarization.

CONCLUSIONS

The obesity mice model reveals the catabolism of BCAA was disrupted which will cause the accumulation of BCAA, and high-level BCAA will promote ATMs M1 polarization and increase the pro-inflammatory cytokines in adipose tissue which will cause the insulin resistance in further. Therefore, reducing the circulating level of BCAA can be a therapeutic strategy in obesity and insulin resistance patients.

Butein derivatives prevent obesity and improve insulin resistance through the induction of energy expenditure in high-fat diet-fed obese mice

Obesity is a global public health problem and is related with fatal diseases such as cancer and cardiovascular and metabolic diseases. Medical and lifestyle-related strategies to combat obesity have their limitations. White adipose tissue (WAT) browning is a promising strategy for increasing energy expenditure in individuals with obesity. Uncoupling protein 1 (UCP1) drives WAT browning. We previously screened natural products that enable induction of Ucp1 and demonstrated that these natural products induced WAT browning and increased energy expenditure in mice with diet-induced obesity. In this study, we aimed to extensively optimise the structure of compound 1, previously shown to promote WAT browning. Compound 3 s exhibited a significantly higher ability to induce Ucp1 in white and brown adipocytes than did compound 1. A daily injection of compound 3 s at 5 mg/kg prevented weight gain by 13.6 % in high-fat diet-fed mice without any toxicological observation. In addition, compound 3 s significantly improved glucose homeostasis, decreased serum triacylglycerol levels, and reduced total cholesterol and LDL cholesterol levels, without altering dietary intake or physical activity. Pharmaceutical properties such as solubility, lipophilicity, and membrane permeability as well as metabolic stability, half-life (T1/2), and blood exposure ratio of i.p to i.v were significantly improved in compound 3 s when compared with those in compound 1. Regarding the mode of action of WAT browning, the induction of Ucp1 and Prdm4 by compounds 1 and 3 s was dependent on Akt1 in mouse embryonic fibroblasts. Therefore, this study suggests the potential of compound 3 s as a therapeutic agent for individuals with obesity and related metabolic diseases, which acts through the induction of WAT browning as well as brown adipose tissue activation.

Bone morphogenetic protein 4 alleviates pulmonary fibrosis by regulating macrophages

Fibrosis is a pathological change mainly characterized by an increase of fibrous connective tissue and decrease of parenchymal cells. Its continuous progress may lead to the destruction of organ structure and function decline. An excess of alternatively activated M2 macrophages have been considered crucial candidates in the progression of fibrosis. Bone morphogenetic proteins (BMPs), a group of multifunctional growth factors, are essential for organ development and pathophysiological process, however, the roles that BMPs play in innate immune homeostasis in the development of fibrosis and the downstream signals have not been fully explored. In the current study, we firstly found that the expression of BMP4 was significantly down-regulated in human and mouse fibrosis samples. Then we investigated the effects of BMP4 on macrophage polarization in IL-4 environment and related molecular mechanisms, and found that BMP4 caused a decrease in polarized response towards M2, reflected in the expression of the markers Fizz1, Ym1 and Arg1, together with an inhibition in Stat6 phosphorylation. This relied on the Smad1/5/8 signaling, which had a crosstalk with Stat6. Moreover, the in vivo study showed that BMP4 treatment can reduce collagen deposition and delay the development of experimental pulmonary fibrosis in mice by inhibiting M2 macrophages through adoptive transfer experiment. These findings revealed a novel role of BMP4 in regulating macrophages, offering potential strategies for treating pulmonary fibrosis.

Obesity, Metabolic Syndrome, and Osteoarthritis Require Integrative Understanding and Management

Osteoarthritis (OA) is a progressive chronic disease affecting the articular joints, leading to pain and disability. Unlike traditional views that primarily link OA to aging, recent understanding portrays it as a multifactorial degenerative disease of the entire joint. Emerging research highlights metabolic and immune dysregulation in OA pathogenesis, emphasizing the roles of obesity, dyslipidemia, and insulin resistance in altering joint homeostasis. Recent studies have increasingly focused on the complex role of white adipose tissue (WAT) in OA. WAT not only serves metabolic functions but also plays a critical role in systemic inflammation through the release of various adipokines. These adipokines, including leptin and adiponectin, have been implicated in exacerbating cartilage erosion and promoting inflammatory pathways within joint tissues. The overlapping global crises of obesity and metabolic syndrome have significantly impacted joint health. Obesity, now understood to contribute to mechanical joint overload and metabolic dysregulation, heightens the risk of developing OA, particularly in the knee. Metabolic syndrome compounds these risks by inducing chronic inflammation and altering macrophage activity within the joints. The multifaceted effects of obesity and metabolic syndrome extend beyond simple joint loading. These conditions disrupt normal joint function by modifying tissue composition, promoting inflammatory macrophage polarization, and impairing chondrocyte metabolism. These changes contribute to OA progression, highlighting the need for targeted therapeutic strategies that address both the mechanical and biochemical aspects of the disease. Recent advances in understanding the molecular pathways involved in OA suggest potential therapeutic targets. Interventions that modulate macrophage polarization, improve chondrocyte function, or normalize adipokine levels could serve as preventative or disease-modifying therapies. Exploring the role of diet, exercise, and pharmacological interventions in modulating these pathways offers promising avenues for reducing the burden of OA. Furthermore, such methods could prove cost-effective, avoiding the increase in access to healthcare.

MiR-106a-5p targets PFKFB3 and improves sepsis through regulating macrophage pyroptosis and inflammatory response

The enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase isoform 3 (PFKFB3) is a critical regulator of glycolysis and plays a key role in modulating the inflammatory response, thereby contributing to the development of inflammatory diseases such as sepsis. Despite its importance, the development of strategies to target PFKFB3 in the context of sepsis remains challenging. In this study, we employed a miRNA-based approach to decrease PFKFB3 expression. Through multiple meta-analyses, we observed a downregulation of miR-106a-5p expression and an upregulation of PFKFB3 expression in clinical sepsis samples. These changes were also confirmed in blood monocytes from patients with early sepsis and from a mouse model of lipopolysaccharide (LPS)-induced sepsis. Overexpression of miR-106a-5p significantly decreased the LPS-induced increase in glycolytic capacity, inflammatory response, and pyroptosis in macrophages. Mechanistically, we identified PFKFB3 as a direct target protein of miR-106a-5p and demonstrated its essential role in LPS-induced pyroptosis and inflammatory response in macrophages. Furthermore, treatment with agomir-miR-106a-5p conferred a protective effect in an LPS mouse model of sepsis, but this effect was attenuated in myeloid-specific Pfkfb3 KO mice. These findings indicate that miR-106a-5p inhibits macrophage pyroptosis and inflammatory response in sepsis by regulating PFKFB3-mediated glucose metabolism, representing a potential therapeutic option for the treatment of sepsis.

Traditional Chinese medicine in regulating macrophage polarization in immune response of inflammatory diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Numerous studies have demonstrated that various traditional Chinese medicines (TCMs) exhibit potent anti-inflammatory effects against inflammatory diseases mediated through macrophage polarization and metabolic reprogramming.

AIM OF THE STUDY

The objective of this review was to assess and consolidate the current understanding regarding the pathogenic mechanisms governing macrophage polarization in the context of regulating inflammatory diseases. We also summarize the mechanism action of various TCMs on the regulation of macrophage polarization, which may contribute to facilitate the development of natural anti-inflammatory drugs based on reshaping macrophage polarization.

MATERIALS AND METHODS

We conducted a comprehensive review of recently published articles, utilizing keywords such as "macrophage polarization" and "traditional Chinese medicines" in combination with "inflammation," as well as "macrophage polarization" and "inflammation" in conjunction with "natural products," and similar combinations, to search within PubMed and Google Scholar databases.

RESULTS

A total of 113 kinds of TCMs (including 62 components of TCMs, 27 TCMs as well as various types of extracts of TCMs and 24 Chinese prescriptions) was reported to exert anti-inflammatory effects through the regulation of key pathways of macrophage polarization and metabolic reprogramming.

CONCLUSIONS

In this review, we have analyzed studies concerning the involvement of macrophage polarization and metabolic reprogramming in inflammation therapy. TCMs has great advantages in regulating macrophage polarization in treating inflammatory diseases due to its multi-pathway and multi-target pharmacological action. This review may contribute to facilitate the development of natural anti-inflammatory drugs based on reshaping macrophage polarization.

Use of Optical Redox Imaging to Quantify Alveolar Macrophage Redox State in Infants: Proof of Concept Experiments in a Murine Model and Human Tracheal Aspirates Samples

Emerging data indicate that lung macrophages (LM) may provide a novel biomarker to classify disease endotypes in bronchopulmonary dysplasia (BPD), a form of infant chronic lung disease, and that augmentation of the LM phenotype may be a potential therapeutic target. To contribute to this area of research, we first used Optical Redox Imaging (ORI) to characterize the responses to H2O2-induced oxidative stress and caffeine treatment in an in vitro model of mouse alveolar macrophages (AM). H2O2 caused a dose-dependent decrease in NADH and an increase in FAD-containing flavoproteins (Fp) and the redox ratio Fp/(NADH + Fp). Caffeine treatment did not affect Fp but significantly decreased NADH with doses of ≥50 µM, and 1000 µM caffeine treatment significantly increased the redox ratio and decreased the baseline level of mitochondrial ROS (reactive oxygen species). However, regardless of whether AM were pretreated with caffeine or not, the mitochondrial ROS levels increased to similar levels after H2O2 challenge. We then investigated the feasibility of utilizing ORI to examine macrophage redox status in tracheal aspirate (TA) samples obtained from premature infants receiving invasive ventilation. We observed significant heterogeneity in NADH, Fp, Fp/(NADH + Fp), and mitochondrial ROS of the TA macrophages. We found a possible positive correlation between gestational age and NADH and a negative correlation between mean airway pressure and NADH that provides hypotheses for future testing. Our study demonstrates that ORI is a feasible technique to characterize macrophage redox state in infant TA samples and supports further use of this method to investigate lung macrophage-mediated disease endotypes in BPD.

Lactic acid in macrophage polarization: A factor in carcinogenesis and a promising target for cancer therapy

Cancer remains a formidable challenge, continually revealing its intricate nature and demanding novel treatment approaches. Within this intricate landscape, the tumor microenvironment and its dynamic components have gained prominence, particularly macrophages that can adopt diverse polarization states, exerting a profound influence on cancer progression. Recent revelations have spotlighted lactic acid as a pivotal player in this complex interplay. This review systematically explores lactic acid's multifaceted role in macrophage polarization, focusing on its implications in carcinogenesis. We commence by cultivating a comprehensive understanding of the tumor microenvironment and the pivotal roles played by macrophages. The dynamic landscape of macrophage polarization, typified by M1 and M2 phenotypes, is dissected to reveal its substantial impact on tumor progression. Lactic acid, a metabolic byproduct, emerges as a key protagonist, and we meticulously unravel the mechanisms underpinning its generation within cancer cells, shedding light on its intimate association with glycolysis and its transformative effects on the tumor microenvironment. Furthermore, we decipher the intricate molecular framework that underlies lactic acid's pivotal role in facilitating macrophage polarization. Our review underscores lactic acid's dual role in carcinogenesis, orchestrating tumor growth and immune modulation within the tumor microenvironment, thereby profoundly influencing the balance between pro-tumor and anti-tumor immune responses. This duality highlights the therapeutic potential of selectively manipulating lactic acid metabolism for cancer treatment. Exploring strategies to inhibit lactic acid production by tumor cells, novel approaches to impede lactic acid transport in the tumor microenvironment, and the burgeoning field of immunotherapeutic cancer therapies utilizing lactic acid-induced macrophage polarization form the core of our investigation.

Polarization of M2 Tumor-Associated Macrophages (TAMs) in Cancer Immunotherapy

We have witnessed in the last decade new milestones in the treatment of various resistant cancers with new immunotherapeutic modalities. These advances have resulted in significant objective durable clinical responses in a subset of cancer patients. These findings strongly suggested that immunotherapy should be considered for the treatment of all subsets of cancer patients. Accordingly, the mechanisms underlying resistance to immunotherapy must be explored and develop new means to target these resistant factors. One of the pivotal resistance mechanisms in the tumor microenvironment (TME) is the high infiltration of tumor-associated macrophages (TAMs) that are highly immunosuppressive and responsible, in large part, of cancer immune evasion. Thus, various approaches have been investigated to target the TAMs to restore the anti-tumor immune response. One approach is to polarize the M2 TAMS to the M1 phenotype that participates in the activation of the anti-tumor response. In this review, we discuss the various and differential properties of the M1 and M2 phenotypes, the molecular signaling pathways that participate in the polarization, and various approaches used to target the polarization of the M2 TAMs into the M1 anti-tumor phenotype. These approaches include inhibitors of histone deacetylases, PI3K inhibitors, STAT3 inhibitors, TLR agonists, and metabolic reprogramming. Clearly, due to the distinct features of various cancers and their heterogeneities, a single approach outlined above might only be effective against some cancers and not others. In addition, targeting by itself may not be efficacious unless used in combination with other therapeutic modalities.

Viperin mutation is linked to immunity, immune cell dynamics, and metabolic alteration during VHSV infection in zebrafish

Viperin is a prominent antiviral protein found in animals. The primary function of Viperin is the production of 3'-deoxy-3',4'-didehydro-cytidine triphosphate (ddhCTP), an inhibitory nucleotide involved in viral RNA synthesis. Studies in mammalian models have suggested that ddhCTP interferes with metabolic proteins. However, this hypothesis has yet to be tested in teleost. In this study, the role of Viperin in regulating metabolic alterations during viral hemorrhagic septicemia virus (VHSV) infection was tested. When infected with VHSV, viperin -/- fish showed considerably higher mortality rates. VHSV copy number and the expression of the NP gene were significantly increased in viperin -/- fish. Metabolic gene analysis revealed significant differences in soda, hif1a, fasn, and acc expression, indicating their impact on metabolism. Cholesterol analysis in zebrafish larvae during VHSV infection showed significant upregulation of cholesterol production without Viperin. In vitro analysis of ZF4 cells suggested a considerable reduction in lipid production and a significant upregulation of reactive oxygen species (ROS) generation with the overexpression of viperin. Neutrophil and macrophage recruitment were significantly modulated in viperin -/- fish compared to the wild-type (WT) fish. Thus, we have demonstrated that Viperin plays a role in interfering with metabolic alterations during VHSV infection.

MiR-223-3p attenuates M1 macrophage polarization via suppressing the Notch signaling pathway and NLRP3-mediated pyroptosis in experimental autoimmune uveitis

Autoimmune uveitis is an intraocular inflammatory disease with a high blindness rate in developed countries such as the United States. It is pressing to comprehend the pathogenesis of autoimmune uveitis and develop novel schemes for its treatment. In the present research, we demonstrated that the Notch signaling pathway was activated, and the level of miR-223-3p was significantly reduced in rats with experimental autoimmune uveitis (EAU) compared with the level of normal rats. To investigate the relationship between miR-223-3p and Notch signaling, EAU rats received miR-223-3p-carrying lentivirus, miR-223-3p vector-carrying lentivirus (miR-223-3p-N), and γ-secretase inhibitor (DAPT), respectively. The results of Q-PCR, immunological experiments, and flow cytometry analysis all support the hypothesis that both miR-223-3p and DAPT, a Notch signaling pathway inhibitor, had similar inhibitory effects on the EAU pathological process. That is to say, they could both inhibit the activation of the Notch signaling pathway via modulating recombination signal binding protein-Jκ (RBPJ) to restore the polarization imbalance of M/M2 macrophages in EAU rats. In addition, miR-223-3p could also inhibit NLRP3 inflammasome activation and inflammasome-induced pyroptosis in ocular tissues. Taken together, our findings indicate that miR-223-3p serves as an important regulator in M1 macrophage polarization and pyroptosis, thereby alleviating the inflammatory response in uveitis.

Cytokine Profiling of Cyst Fluid and Tumor-Associated Macrophages in Cystic Vestibular Schwannoma

BACKGROUND

The vestibular schwannoma (VS) secretome can initiate monocyte recruitment and macrophage polarization to M1 (proinflammatory) and/or M2 (protumorigenic) phenotypes, which in turn secrete additional cytokines that contribute to the tumor microenvironment. Profiling cyst fluid and cerebrospinal fluid (CSF) in cystic VS provides a unique opportunity to understand mechanisms that may contribute to tumor progression and cyst formation.

HYPOTHESIS

Cystic VSs secrete high levels of cytokines into cyst fluid and express abundant M1 and M2 macrophages.

METHODS

Tumor, CSF, and cyst fluid were prospectively collected from 10 cystic VS patients. Eighty cytokines were measured in fluid samples using cytokine arrays and compared with normal CSF from normal donors. Immunofluorescence was performed for CD80 + M1 and CD163 + M2 macrophage markers. Demographic, audiometric, and radiographic information was obtained through retrospective chart review.

RESULTS

Cyst fluid expressed more osteopontin and monocyte chemotactic protein-1 (MCP-1; p < 0.0001), when compared with normal CSF. Cyst fluid also expressed more protein ( p = 0.0020), particularly MCP-1 ( p < 0.0001), than paired CSF from the same subjects. MCP-1 expression in cyst fluid correlated with CD80 + staining in VS tissue ( r = 0.8852; p = 0.0015) but not CD163 + staining.

CONCLUSION

Cyst fluid from cystic VS harbored high levels of osteopontin and MCP-1, which are cytokines important in monocyte recruitment and macrophage polarization. MCP-1 may have a significant role in molding the tumor microenvironment, by polarizing monocytes to CD80 + M1 macrophages in cystic VS. Further investigations into the role of cytokines and macrophages in VS may lead to new avenues for therapeutic intervention.

The dysregulation of immune cells induced by uric acid: mechanisms of inflammation associated with hyperuricemia and its complications

Changes in lifestyle induce an increase in patients with hyperuricemia (HUA), leading to gout, gouty arthritis, renal damage, and cardiovascular injury. There is a strong inflammatory response in the process of HUA, while dysregulation of immune cells, including monocytes, macrophages, and T cells, plays a crucial role in the inflammatory response. Recent studies have indicated that urate has a direct impact on immune cell populations, changes in cytokine expression, modifications in chemotaxis and differentiation, and the provocation of immune cells by intrinsic cells to cause the aforementioned conditions. Here we conducted a detailed review of the relationship among uric acid, immune response, and inflammatory status in hyperuricemia and its complications, providing new therapeutic targets and strategies.

Adropin deficiency worsens TNBS-induced colitis

The aim of this study was to describe the effects of adropin deficiency on the distribution, phenotype and pathological phenotype of macrophages in colonic and mesenteric tissues of AdrKO (Enho-/-) mice, so as to explore the mechanism of adropin deficiency in spontaneous and experimental colitis. In this study, RNA-seq and metabonomics were used to screen the regulatory mechanism of adropin on the phenotypic transformation of macrophages. We found that adropin levels in active UC patients were significantly lower than those in normal subjects and remission UC patients, and at the same time, a large number of proinflammatory M1-type macrophages were infiltrated in the mesenteric tissue of colonic tissues from UC and CD patients. At the same time, spontaneous colitis occurred in Enho-/- (adropin-deficient)C57BL/6 mice, and there was an imbalance of M2 → M1 polarization of macrophages in colon and mesentery of Enho-/- mice. In vivo, it has showed that adropin deficiency could exacerbate the pathological phenotype of colitis induced by TNBS. In vitro, adropin was used to intervene RAW264.7 macrophages, and then combined analysis of RNA-seq and metabolomics demonstrated that adropin regulated lipid metabolism of macrophages through PPARγ, thus promoting the repolarization of macrophages from M1 to M2. Adropin deficiency led to an imbalance in the phenotypic distribution of macrophages infiltrating the colon and mesenteric tissues, namely, an increase in M1 type, which led to the occurrence and development of colitis.

The role and mechanisms of macrophage polarization and hepatocyte pyroptosis in acute liver failure

Acute liver failure (ALF) is a severe liver disease caused by disruptions in the body's immune microenvironment. In the early stages of ALF, Kupffer cells (KCs) become depleted and recruit monocytes derived from the bone marrow or abdomen to replace the depleted macrophages entering the liver. These monocytes differentiate into mature macrophages, which are activated in the immune microenvironment of the liver and polarized to perform various functions. Macrophage polarization can occur in two directions: pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages. Controlling the ratio and direction of M1 and M2 in ALF can help reduce liver injury. However, the liver damage caused by pyroptosis should not be underestimated, as it is a caspase-dependent form of cell death. Inhibiting pyroptosis has been shown to effectively reduce liver damage induced by ALF. Furthermore, macrophage polarization and pyroptosis share common binding sites, signaling pathways, and outcomes. In the review, we describe the role of macrophage polarization and pyroptosis in the pathogenesis of ALF. Additionally, we preliminarily explore the relationship between macrophage polarization and pyroptosis, as well as their effects on ALF.

Role of glycolysis in diabetic atherosclerosis

Diabetes mellitus is a kind of typical metabolic disorder characterized by elevated blood sugar levels. Atherosclerosis (AS) is one of the most common complications of diabetes. Modern lifestyles and trends that promote overconsumption and unhealthy practices have contributed to an increase in the annual incidence of diabetic AS worldwide, which has created a heavy burden on society. Several studies have shown the significant effects of glycolysis-related changes on the occurrence and development of diabetic AS, which may serve as novel thera-peutic targets for diabetic AS in the future. Glycolysis is an important metabolic pathway that generates energy in various cells of the blood vessel wall. In particular, it plays a vital role in the physiological and pathological activities of the three important cells, Endothelial cells, macrophages and vascular smooth muscle cells. There are lots of similar mechanisms underlying diabetic and common AS, the former is more complex. In this article, we describe the role and mechanism underlying glycolysis in diabetic AS, as well as the therapeutic targets, such as trained immunity, microRNAs, gut microbiota, and associated drugs, with the aim to provide some new perspectives and potentially feasible programs for the treatment of diabetic AS in the foreseeable future.

Mammary Epithelial Cell-Derived Exosomal miR-221-3p Regulates Macrophage Polarization by Targeting Igf2bp2 during Mastitis

Mastitis affects the milk quality and yield and is the most expensive disease in dairy cows. Elucidation of the pathogenesis of mastitis is of great importance for disease control. As a medium of intercellular communication, exosomes play key roles in various inflammatory diseases by regulating macrophage polarization. However, the molecular factors in exosomes that mediate the intercellular communication between mammary epithelial cells and macrophages during mastitis remain to be further explored. In this study, we isolated and identified mammary epithelial cell-derived exosomes from a lipopolysaccharide (LPS)/lipoteichoic acid (LTA)-induced mastitis cell model, and we demonstrated that exosomes from LPS/LTA-stimulated mammary epithelial cells promote M1-type macrophage polarization in vivo and in vitro. Based on the results of high-throughput sequencing, we constructed a differential miRNA (microRNA) expression profile of exosomes and demonstrated that miR-221-3p was highly expressed. Furthermore, in vivo and in vitro experiments, combined with coculture experiments and fluorescence tracing, showed that high miR-221-3p expression promoted M1-type macrophage polarization, demonstrating the transcellular role of miR-221-3p. Mechanistically, dual luciferase reporter gene assays and rescue assays showed that miR-221-3p regulated macrophage polarization by targeting Igf2bp2. The results of this study will deepen our understanding of the pathogenesis of mastitis, and the molecular regulatory axis that was established in this study is expected to be a target for mastitis treatment.

pH/NIR-responsive and self-healing coatings with bacteria killing, osteogenesis, and angiogenesis performances on magnesium alloy

Although biodegradable polymer coatings can impede corrosion of magnesium (Mg)-based orthopedic implants, they are prone to excessive degradation and accidental scratching in practice. Bone implant-related infection and limited osteointegration are other factors that adversely impact clinical application of Mg-based biomedical implants. Herein, a self-healing polymeric coating is constructed on the Mg alloy together with incorporation of a stimuli-responsive drug delivery nanoplatform by a spin-spray layer-by-layer (SSLbL) assembly technique. The nanocontainers are based on simvastatin (SIM)-encapsulated hollow mesoporous silica nanoparticles (S@HMSs) modified with polydopamine (PDA) and polycaprolactone diacrylate (PCL-DA) bilayer. Owing to the dynamic reversible reactions, the hybrid coating shows a fast, stable, and cyclical water-enabled self-healing capacity. The antibacterial assay indicates good bacteria-killing properties under near infrared (NIR) irradiation due to synergistic effects of hyperthermia, reactive oxygens species (ROS), and SIM leaching. In vitro results demonstrate that NIR laser irradiation promotes the cytocompatibility, osteogenesis, and angiogenesis. The coating facilitates alkaline phosphatase activity and expedites extracellular matrix mineralization as well as expression of osteogenesis-related genes. This study reveals a useful strategy to develop multifunctional coatings on bioabsorbable Mg alloys for orthopedic implants.

Insights into the tumor-stromal-immune cell metabolism cross talk in ovarian cancer

The ovarian cancer tumor microenvironment (TME) consists of a constellation of abundant cellular components, extracellular matrix, and soluble factors. Soluble factors, such as cytokines, chemokines, structural proteins, extracellular vesicles, and metabolites, are critical means of noncontact cellular communication acting as messengers to convey pro- or antitumorigenic signals. Vast advancements have been made in our understanding of how cancer cells adapt their metabolism to meet environmental demands and utilize these adaptations to promote survival, metastasis, and therapeutic resistance. The stromal TME contribution to this metabolic rewiring has been relatively underexplored, particularly in ovarian cancer. Thus, metabolic activity alterations in the TME hold promise for further study and potential therapeutic exploitation. In this review, we focus on the cellular components of the TME with emphasis on 1) metabolic signatures of ovarian cancer; 2) understanding the stromal cell network and their metabolic cross talk with tumor cells; and 3) how stromal and tumor cell metabolites alter intratumoral immune cell metabolism and function. Together, these elements provide insight into the metabolic influence of the TME and emphasize the importance of understanding how metabolic performance drives cancer progression.

Reprogramming of breast tumor-associated macrophages with modulation of arginine metabolism

HER2+ breast tumors have abundant immune-suppressive cells, including M2-type tumor associated macrophages (TAMs). While TAMs consist of the immune-stimulatory M1-type and immune-suppressive M2-type, M1/M2-TAM ratio is reduced in immune-suppressive tumors, contributing to their immunotherapy refractoriness. M1 vs. M2-TAM formation depends on differential arginine metabolism, where M1-TAMs convert arginine to nitric oxide (NO) and M2-TAMs convert arginine to polyamines (PAs). We hypothesize that such distinct arginine metabolism in M1- vs M2-TAMs is attributed to different availability of BH4 (NO synthase cofactor) and that its replenishment would reprogram M2-TAMs to M1-TAMs. Recently, we reported that sepiapterin (SEP), the endogenous BH4 precursor, elevates the expression of M1-TAM markers within HER2+ tumors. Here, we show that SEP restores BH4 levels in M2-TAMs, which then redirects arginine metabolism to NO synthesis and converts M2-TAMs to M1-TAMs. The reprogrammed TAMs exhibit full-fledged capabilities of antigen presentation and induction of effector T cells to trigger immunogenic cell death of HER2+ cancer cells. This study substantiates the utility of SEP in metabolic shift of HER2+ breast tumor microenvironment as a novel immunotherapeutic strategy.

NOS inhibition reverses TLR2-induced chondrocyte dysfunction and attenuates age-related osteoarthritis

Osteoarthritis (OA) is a joint disease featuring cartilage breakdown and chronic pain. Although age and joint trauma are prominently associated with OA occurrence, the trigger and signaling pathways propagating their pathogenic aspects are ill defined. Following long-term catabolic activity and traumatic cartilage breakdown, debris accumulates and can trigger Toll-like receptors (TLRs). Here we show that TLR2 stimulation suppressed the expression of matrix proteins and induced an inflammatory phenotype in human chondrocytes. Further, TLR2 stimulation impaired chondrocyte mitochondrial function, resulting in severely reduced adenosine triphosphate (ATP) production. RNA-sequencing analysis revealed that TLR2 stimulation upregulated nitric oxide synthase 2 (NOS2) expression and downregulated mitochondria function-associated genes. NOS inhibition partially restored the expression of these genes, and rescued mitochondrial function and ATP production. Correspondingly, Nos2-/- mice were protected from age-related OA development. Taken together, the TLR2-NOS axis promotes human chondrocyte dysfunction and murine OA development, and targeted interventions may provide therapeutic and preventive approaches in OA.

Therapeutic Activity of Green Tea Epigallocatechin-3-Gallate on Metabolic Diseases and Non-Alcoholic Fatty Liver Diseases: The Current Updates

Green tea polyphenols have numerous functions including antioxidation and modulation of various cellular proteins and are thus beneficial against metabolic diseases including obesity, type 2 diabetes, cardiovascular and non-alcoholic fatty liver diseases, and their comorbidities. Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenol in green tea and is attributed to antioxidant and free radical scavenging activities, and the likelihood of targeting multiple metabolic pathways. It has been shown to exhibit anti-obesity, anti-inflammatory, anti-diabetic, anti-arteriosclerotic, and weight-reducing effects in humans. Worldwide, the incidences of metabolic diseases have been escalating across all age groups in modern society. Therefore, EGCG is being increasingly investigated to address the problems. This review presents the current updates on the effects of EGCG on metabolic diseases, and highlights evidence related to its safety. Collectively, this review brings more evidence for therapeutic application and further studies on EGCG and its derivatives to alleviate metabolic diseases and non-alcoholic fatty liver diseases.

Regulatory Mechanism of M1/M2 Macrophage Polarization in the Development of Autoimmune Diseases

Macrophages are innate immune cells in the organism and can be found in almost tissues and organs. They are highly plastic and heterogeneous cells and can participate in the immune response, thereby playing a crucial role in maintaining the immune homeostasis of the body. It is well known that undifferentiated macrophages can polarize into classically activated macrophages (M1 macrophages) and alternatively activated macrophages (M2 macrophages) under different microenvironmental conditions. The directions of macrophage polarization can be regulated by a series of factors, including interferon, lipopolysaccharide, interleukin, and noncoding RNAs. To elucidate the role of macrophages in various autoimmune diseases, we searched the literature on macrophages with the PubMed database. Search terms are as follows: macrophages, polarization, signaling pathways, noncoding RNA, inflammation, autoimmune diseases, systemic lupus erythematosus, rheumatoid arthritis, lupus nephritis, Sjogren's syndrome, Guillain-Barré syndrome, and multiple sclerosis. In the present study, we summarize the role of macrophage polarization in common autoimmune diseases. In addition, we also summarize the features and recent advances with a particular focus on the immunotherapeutic potential of macrophage polarization in autoimmune diseases and the potentially effective therapeutic targets.

Cellular crosstalk in atherosclerotic plaque microenvironment

Atherosclerosis is an underlying pathology of many vascular diseases as a result of cellular, structural and molecular dysfunctions within the sub-endothelial space. This review deals with the events involved in the formation, growth and remodeling of plaque, including the cell recruitment, cell polarization, and cell fat droplets. It also describes cross talking between endothelial cells, macrophages, and vascular smooth muscle cells, as well as the cellular pathways involved in plaque development in the plaque microenvironment. Finally, it describes the plaque structural components and the role of factors involved in the rupture and erosion of plaques in the vessel. Video Abstract.

Crude polysaccharide from Danggui Buxue decoction enhanced the anti-tumor effect of gemcitabine by remodeling tumor-associated macrophages

Tumor-associated macrophages (TAMs) with an M2-phenotype mediate gemcitabine resistance to cancer by influencing the metabolic enzymes of gemcitabine and releasing competitive deoxycytidine (dC). Our previous studies showed that Danggui Buxue Decoction (DBD), a traditional Chinese medicinal recipe, enhances the anti-tumor activity of gemcitabine in vivo and alleviates gemcitabine-induced myelosuppression. However, the material basis and exact mechanism underlying its enhanced effects remain unclear. In this study, a bioactive polysaccharide consisting of arabinose, mannose, ribose, and glucose was isolated from DBD. In vivo results demonstrated that DBD crude polysaccharide (DBDP) ameliorated gemcitabine-induced immune system disorders. Moreover, DBDP improved the sensitivity of Lewis lung carcinoma-bearing mice to gemcitabine by reshaping the tumor-promoting M2-like macrophages into tumor-inhibiting M1-phenotypes. Furthermore, in vitro results further revealed that DBDP blocked the protective effects of TAMs and M2-macrophages against gemcitabine by inhibiting the excessive secretion of dC and decreasing the high expression of cytidine deaminase. In conclusion, our results demonstrated that DBDP, as the pharmacodynamic material basis of DBD, enhanced the anti-tumor activity of gemcitabine against lung cancer in vitro and in vivo, which was associated with remodeling of the M2-phenotype.

Macrophages in immunoregulation and therapeutics

Macrophages exist in various tissues, several body cavities, and around mucosal surfaces and are a vital part of the innate immune system for host defense against many pathogens and cancers. Macrophages possess binary M1/M2 macrophage polarization settings, which perform a central role in an array of immune tasks via intrinsic signal cascades and, therefore, must be precisely regulated. Many crucial questions about macrophage signaling and immune modulation are yet to be uncovered. In addition, the clinical importance of tumor-associated macrophages is becoming more widely recognized as significant progress has been made in understanding their biology. Moreover, they are an integral part of the tumor microenvironment, playing a part in the regulation of a wide variety of processes including angiogenesis, extracellular matrix transformation, cancer cell proliferation, metastasis, immunosuppression, and resistance to chemotherapeutic and checkpoint blockade immunotherapies. Herein, we discuss immune regulation in macrophage polarization and signaling, mechanical stresses and modulation, metabolic signaling pathways, mitochondrial and transcriptional, and epigenetic regulation. Furthermore, we have broadly extended the understanding of macrophages in extracellular traps and the essential roles of autophagy and aging in regulating macrophage functions. Moreover, we discussed recent advances in macrophages-mediated immune regulation of autoimmune diseases and tumorigenesis. Lastly, we discussed targeted macrophage therapy to portray prospective targets for therapeutic strategies in health and diseases.

Leishmaniasis: Immune Cells Crosstalk in Macrophage Polarization

Leishmaniasis is a complex infectious parasitic disease caused by protozoa of the genus Leishmania, belonging to a group of neglected tropical diseases. It establishes significant global health challenges, particularly in socio-economically disadvantaged regions. Macrophages, as innate immune cells, play a crucial role in initiating the inflammatory response against the pathogens responsible for this disease. Macrophage polarization, the process of differentiating macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, is essential for the immune response in leishmaniasis. The M1 phenotype is associated with resistance to Leishmania infection, while the M2 phenotype is predominant in susceptible environments. Notably, various immune cells, including T cells, play a significant role in modulating macrophage polarization by releasing cytokines that influence macrophage maturation and function. Furthermore, other immune cells can also impact macrophage polarization in a T-cell-independent manner. Therefore, this review comprehensively examines macrophage polarization's role in leishmaniasis and other immune cells' potential involvement in this intricate process.

Cell-penetrating TLR inhibitor peptide alleviates ulcerative colitis by the functional modulation of macrophages

Toll-like receptors (TLRs) have a crucial role not only in triggering innate responses against microbes but in orchestrating an appropriate adaptive immunity. However, deregulated activation of TLR signaling leads to chronic inflammatory conditions such as inflammatory bowel disease (IBD). In this study, we evaluated the immunomodulatory potential of a TLR inhibitor in the form of a cell-penetrating peptide using an ulcerative colitis animal model. A peptide derived from the TIR domain of the TLR adaptor molecule TIRAP that was conjugated with a cell-penetrating sequence (cpTLR-i) suppressed the induction of pro-inflammatory cytokines such as TNF-α and IL-1β in macrophages. In DSS-induced colitis mice, cpTLR-i treatment ameliorated colitis symptoms, colonic tissue damage, and mucosal inflammation. Intriguingly, cpTLR-i attenuated the induction of TNF-α-expressing proinflammatory macrophages while promoting that of regulatory macrophages expressing arginase-1 and reduced type 17 helper T cell (Th17) responses in the inflamed colonic lamina propria. An in vitro study validated that cpTLR-i enhanced the differentiation of monocyte-driven macrophages into mature macrophages with a regulatory phenotype in a microbial TLR ligand-independent manner. Furthermore, the cocultivation of CD4 T cells with macrophages revealed that cpTLR-i suppressed the activation of Th17 cells through the functional modulation of macrophages. Taken together, our data show the immunomodulatory potential of the TLR inhibitor peptide and suggest cpTLR-i as a novel therapeutic candidate for the treatment of IBD.

PSTPIP2 alleviates obesity associated adipose tissue inflammation and insulin resistance in diabetes mice through promoting M2 macrophage polarization via activation of PPARγ

BACKGROUND

Proline-serine-threonine phosphatase-interacting protein 2 (PSTPIP2) plays a role in inflammatory disease. In diabetes, very little is known about PSTPIP2 until now. Hence, this study aimed to determine PSTPIP2 functional role in diabetes.

METHODS

Diabetes mouse model was constructed by feeding high fat diet (HFD). Intraperitoneal glucose tolerance test and intraperitoneal insulin tolerance test were examined the glucose and insulin tolerance. The expression of genes and proteins was detected by quantitative real time PCR, immunohistochemistry and western blotting. The pathological changes of epididymal adipose tissues were examined by hematoxylin-eosin staining. RAW264.7 macrophages were treated with GW9662 (PPARγ antagonist). Flow cytometry examined the proportion of M1/M2 macrophages.

RESULTS

HFD enhanced the body weight, glucose and insulin tolerance, and inhibited PSTPIP2 expression in mice. PSTPIP2 overexpression alleviated glucose and insulin tolerance, reduced inflammation and macrophage accumulation in the epididymal adipose tissues of diabetic mice. The expression of iNOS and TNF-α was increased, the expression of IL-10 and Arg-1 was decreased in diabetic mice, which was abrogated by PSTPIP2 overexpression. In vitro, PSTPIP2 overexpression reduced the proportions of iNOS-positive cells and enhanced the proportions of CD206-positive cells in RAW264.7 cells. PPARγ and p-STAT6 were up-regulated, STAT6 was down-regulated in RAW264.7 cells. GW9662 impaired PSTPIP2 overexpression-mediated up-regulation of Arg-1, YM-1 and FIZZ1 in RAW264.7 cells.

CONCLUSION

PSTPIP2 alleviates obesity associated adipose tissue inflammation and insulin resistance in diabetic mice through promoting M2 macrophage polarization via activation of PPARγ, suggesting that PSTPIP2 is a prospective target for diabetes treatment.

Adipokines in multiple sclerosis patients are related to clinical and radiological measures

BACKGROUND

An imbalance of adipokines, hormones secreted by white adipose tissue, is suggested to play a role in the immunopathology of multiple sclerosis (MS). In people with MS (PwMS) of the same age, we aimed to determine whether the adipokines adiponectin, leptin, and resistin are associated with MS disease severity. Furthermore, we aimed to investigate whether these adipokines mediate the association between body mass index (BMI) and MS disease severity.

METHODS

Adiponectin, resistin, and leptin were determined in serum using ELISA. 288 PwMS and 125 healthy controls (HC) were included from the Project Y cohort, a population-based cross-sectional study of people with MS born in the Netherlands in 1966, and age and sex-matched HC. Adipokine levels and BMI were related to demographic, clinical and disability measures, and MRI-based brain volumes.

RESULTS

Adiponectin levels were 1.2 fold higher in PwMS vs. HC, especially in secondary progressive MS. Furthermore, we found a sex-specific increase in adiponectin levels in primary progressive (PP) male patients compared to male controls. Leptin and resistin levels did not differ between PwMS and HC, however, leptin levels were associated with higher disability (EDSS) and resistin strongly related to brain volumes in progressive patients, especially in several grey matter regions in PPMS. Importantly, correction for BMI did not significantly change the results.

CONCLUSION

In PwMS of the same age, we found associations between adipokines (adiponectin, leptin, and resistin) and a range of clinical and radiological metrics. These associations were independent of BMI, indicating distinct mechanisms.

OPA1 drives macrophage metabolism and functional commitment via p65 signaling

Macrophages are essential players for the host response against pathogens, regulation of inflammation and tissue regeneration. The wide range of macrophage functions rely on their heterogeneity and plasticity that enable a dynamic adaptation of their responses according to the surrounding environmental cues. Recent studies suggest that metabolism provides synergistic support for macrophage activation and elicitation of desirable immune responses; however, the metabolic pathways orchestrating macrophage activation are still under scrutiny. Optic atrophy 1 (OPA1) is a mitochondria-shaping protein controlling mitochondrial fusion, cristae biogenesis and respiration; clear evidence shows that the lack or dysfunctional activity of this protein triggers the accumulation of metabolic intermediates of the TCA cycle. In this study, we show that OPA1 has a crucial role in macrophage activation. Selective Opa1 deletion in myeloid cells impairs M1-macrophage commitment. Mechanistically, Opa1 deletion leads to TCA cycle metabolite accumulation and defective NF-κB signaling activation. In an in vivo model of muscle regeneration upon injury, Opa1 knockout macrophages persist within the damaged tissue, leading to excess collagen deposition and impairment in muscle regeneration. Collectively, our data indicate that OPA1 is a key metabolic driver of macrophage functions.

Immunity and Growth Plasticity of Asian Short-Toed Lark Nestlings in Response to Changes in Food Conditions: Can It Buffer the Challenge of Climate Change-Induced Trophic Mismatch?

Passerine nestlings frequently suffer from sub-optimal food conditions due to climate change-induced trophic mismatch between the nestlings and their optimal food resources. The ability of nestlings to buffer this challenge is less well understood. We hypothesized that poor food conditions might induce a higher immune response and lower growth rate of nestlings, and such physiological plasticity is conducive to nestling survival. To test this, we examined how food (grasshopper nymphs) abundance affects the expression of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-1 β (IL-1β) genes, plasma IGF-1 levels, body mass, and fledging rates in wild Asian short-toed lark (Alaudala cheleensis) nestlings. Linear mixed models revealed that nymph biomass significantly influenced the expression of IFN-γ, TNF-α, and IL-1β genes, and the level of plasma IGF-1. The expressions of IFN-γ, TNF-α, and IL-1β genes were negatively correlated with nymph biomass and plasma IGF-1 level. Plasma IGF-1 level, nestling body mass growth rate, was positively correlated with nymph biomass. Despite a positive correlation between the nestling fledge rate and nymph biomass, more than 60% of nestlings fledged when nymph biomass was at the lowest level. These results suggest that immunity and growth plasticity of nestlings may be an adaptation for birds to buffer the negative effects of trophic mismatch.

Crosstalk between fatty acid metabolism and tumour-associated macrophages in cancer progression

Over the last few decades, cancer has been regarded as an independent and self sustaining progression. The earliest hallmarks of cancer comprise of sustaining proliferative signalling, avoiding growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. Nonetheless, two emerging hallmarks are being described: aberrant metabolic pathways and evasion of immune destruction. Changes in tumour cell metabolism are not restricted to tumour cells alone; the products of the altered metabolism have a direct impact on the activity of immune cells inside the tumour microenvironment, particularly tumour-associated macrophages (TAMs). The complicated process of cancer growth is orchestrated by metabolic changes dictating the tight mutual connection between these cells. Here, we discuss approaches to exploit the interaction of cancer cells' abnormal metabolic activity and TAMs. We also describe ways to exploit it by reprogramming fatty acid metabolism via TAMs.

Targeting tumor-associated macrophages for successful immunotherapy of ovarian carcinoma

Epithelial ovarian cancer (EOC) is among the top five causes of cancer-related death in women, largely reflecting early, prediagnosis dissemination of malignant cells to the peritoneum. Despite improvements in medical therapies, particularly with the implementation of novel drugs targeting homologous recombination deficiency, the survival rates of patients with EOC remain low. Unlike other neoplasms, EOC remains relatively insensitive to immune checkpoint inhibitors, which is correlated with a tumor microenvironment (TME) characterized by poor infiltration by immune cells and active immunosuppression dominated by immune components with tumor-promoting properties, especially tumor-associated macrophages (TAMs). In recent years, TAMs have attracted interest as potential therapeutic targets by seeking to reverse the immunosuppression in the TME and enhance the clinical efficacy of immunotherapy. Here, we review the key biological features of TAMs that affect tumor progression and their relevance as potential targets for treating EOC. We especially focus on the therapies that might modulate the recruitment, polarization, survival, and functional properties of TAMs in the TME of EOC that can be harnessed to develop superior combinatorial regimens with immunotherapy for the clinical care of patients with EOC.

Natural Plant Extract - Loganin: A Hypothesis for Psoriasis Treatment Through Inhibiting Oxidative Stress and Equilibrating Immunity via Regulation of Macrophage Polarization

Psoriasis, a chronic immune-mediated inflammatory skin disease, influences approximately 2-3% of the world's population. At present, the etiology of psoriasis remains unclear and there is still no causal treatment available. Recent studies indicate that oxidative stress (OS) and T cells dysregulation may participate in the pathogenesis of psoriasis, among which M1-dominant macrophage polarization is a crucial contributor. Macrophages mainly polarize into two different subsets, ie, classically activated macrophage (M1) and alternatively activated macrophage (M2). M1 polarization tends to exacerbate psoriasis via producing substantial reactive oxygen species (ROS) and inflammatory mediators, to encourage OS invasion and T cells dysregulation. Thus, targeting M1 polarization can be a possible therapeutic alternative for psoriasis. Loganin, belonging to iridoid glycosides, is a pharmaceutically active ingredient originated from Cornus officinalis, exerting multiple biological activities, eg, immunomodulation, antioxidation, anti-inflammation, etc. More importantly, it could effectively suppress M1 polarization, thereby arresting OS aggression and T cells' dysregulation. Numerous studies have confirmed that loganin is quite reliable for diseases treatment via suppressing M1 polarization. Nevertheless, reports about loganin treating psoriasis have seldom appeared so far. Accordingly, we hold a hypothesis that loganin would availably manage psoriasis through preventing M1 polarization. Data from previous studies guarantee the potential of loganin in control of psoriasis.

Transferrin receptor 2 deficiency promotes macrophage polarization and inflammatory arthritis

OBJECTIVE

Rheumatoid arthritis is an inflammatory joint disease in which synovial iron deposition has been described. Transferrin receptor 2 (Tfr2) represents a critical regulator of systemic iron levels. Loss of Tfr2 function in humans and mice results in iron overload. As iron contributes to inflammatory processes, we investigated whether Tfr2-deletion affects the pathogenesis of inflammatory arthritis in an iron-dependent manner.

METHODS

Using a global and conditional genetic disruption of Tfr2, we assessed the relevance of Tfr2 in K/BxN serum-transfer arthritis (STA) and macrophage polarization.

RESULTS

Male Tfr2^-/- mice subjected to STA developed pronounced joint swelling, and bone erosion as compared to Tfr2^+/+ littermate-controls (P < 0.01). Furthermore, an increase of neutrophils and macrophages/monocytes was observed in the inflammatory infiltrate within the paws of Tfr2^-/- mice. To elucidate whether Tfr2 in myeloid cells has a direct role in the pathogenesis of arthritis or whether the effects were mediated via the systemic iron overload, we induced STA in Tfr2^fl/fl-LysMCre + mice, which showed normal iron-loading. Cre + female mice displayed increased disease development compared to Cre-controls. As macrophages regulate iron availability and innate immunity, we hypothesized that Tfr2-deficiency would polarize macrophages toward a pro-inflammatory state (M1) that contributes to arthritis progression. In response to IFN-γ stimulation, Tfr2^-/- macrophages showed increased expression of M1-like cytokines, IFN-γ-target genes, nitric-oxide production, and prolonged STAT1 activation compared to Tfr2^+/+ macrophages (P < 0.01), while pre-treatment with ruxolitinib abolished Tfr2-driven M1-like polarization.

CONCLUSION

Taken together, these findings suggest a protective role of Tfr2 in macrophages on the progression of arthritis via suppression of M1-like polarization.

Targeting Notch1-YAP Circuit Reprograms Macrophage Polarization and Alleviates Acute Liver Injury in Mice

BACKGROUND & AIMS

Hepatic immune system disorder plays a critical role in the pathogenesis of acute liver injury. The intrinsic signaling mechanisms responsible for dampening excessive activation of liver macrophages are not completely understood. The Notch and Hippo-YAP signaling pathways have been implicated in immune homeostasis. In this study, we investigated the interactive cell signaling networks of Notch1/YAP pathway during acute liver injury.

METHODS

Myeloid-specific Notch1 knockout (Notch1^M-KO) mice and the floxed Notch1 (Notch1^FL/FL) mice were subjected to lipopolysaccharide/D-galactosamine toxicity. Some mice were injected via the tail vein with bone marrow-derived macrophages transfected with lentivirus-expressing YAP. Some mice were injected with YAP siRNA using an in vivo mannose-mediated delivery system.

RESULTS

We found that the activated Notch1 and YAP signaling in liver macrophages were closely related to lipopolysaccharide/D-galactosamine-induced acute liver injury. Macrophage/neutrophil infiltration, proinflammatory mediators, and hepatocellular apoptosis were markedly ameliorated in Notch1^M-KO mice. Importantly, myeloid Notch1 deficiency depressed YAP signaling and facilitated M2 macrophage polarization in the injured liver. Furthermore, YAP overexpression in Notch1^M-KO livers exacerbated liver damage and shifted macrophage polarization toward the M1 phenotype. Mechanistically, macrophage Notch1 signaling could transcriptionally activate YAP gene expression. Reciprocally, YAP transcriptionally upregulated the Notch ligand Jagged1 gene expression and was essential for Notch1-mediated macrophage polarization. Finally, dual inhibition of Notch1 and YAP in macrophages further promoted M2 polarization and alleviated liver damage.

CONCLUSIONS

Our findings underscore a novel molecular insight into the Notch1-YAP circuit for controlling macrophage polarization in acute liver injury, raising the possibility of targeting macrophage Notch1-YAP circuit as an effective strategy for liver inflammation-related diseases.

Inflammation driven metabolic regulation and adaptation in macrophages

Macrophages are a diverse population of phagocytic immune cells involved in the host defense mechanisms and regulation of homeostasis. Usually, macrophages maintain healthy functioning at the cellular level, but external perturbation in their balanced functions can lead to acute and chronic disease conditions. By sensing the cues from the tissue microenvironment, these phagocytes adopt a plethora of phenotypes, such as inflammatory or M1 to anti-inflammatory (immunosuppressive) or M2 subtypes, to fulfill their spectral range of functions. The existing evidence in the literature supports that in macrophages, regulation of metabolic switches and metabolic adaptations are associated with their functional behaviors under various physiological and pathological conditions. Since these macrophages play a crucial role in many disorders, therefore it is necessary to understand their heterogeneity and metabolic reprogramming. Consequently, these macrophages have also emerged as a promising target for diseases in which their role is crucial in driving the disease pathology and outcome (e.g., Cancers). In this review, we discuss the recent findings that link many metabolites with macrophage functions and highlight how this metabolic reprogramming can improve our understanding of cellular malfunction in the macrophages during inflammatory disorders. A systematic analysis of the interconnecting crosstalk between metabolic pathways with macrophages should inform the selection of immunomodulatory therapies for inflammatory diseases.

Metabolism of NK cells during viral infections

Cellular metabolism is essential for the correct function of immune system cells, including Natural Killer cells (NK). These cells depend on energy to carry out their effector functions, especially in the early stages of viral infection. NK cells participate in the innate immune response against viruses and tumors. Their main functions are cytotoxicity and cytokine production. Metabolic changes can impact intracellular signals, molecule production, secretion, and cell activation which is essential as the first line of immune defense. Metabolic variations in different immune cells in response to a tumor or pathogen infection have been described; however, little is known about NK cell metabolism in the context of viral infection. This review summarizes the activation-specific metabolic changes in NK cells, the immunometabolism of NK cells during early, late, and chronic antiviral responses, and the metabolic alterations in NK cells in SARS-CoV2 infection. The modulation points of these metabolic routes are also discussed to explore potential new immunotherapies against viral infections.

The influence of high glucose conditions on macrophages and its effect on the autophagy pathway

Introduction

Macrophages are central cells in mediating the inflammatory response.

Objective and Methods

We evaluated the effect of high glucose conditions on the inflammatory profile and the autophagy pathway in Bone-Marrow Derived Macrophages (BMDM) from diabetic (D-BMDM) (alloxan: 60mg/kg, i.v.) and non-diabetic (ND-BMDM) C57BL/6 mice. BMDM were cultured in medium with normal glucose (5.5 mM), or high glucose (25 mM) concentration and were primed with Nigericin (20µM) stimulated with LPS (100 ng/mL) at times of 30 minutes; 2; 4; 6 and 24 hours, with the measurement of IL-6, IL-1β and TNF-α cytokines.

Results

We have further identified changes in the secretion of pro-inflammatory cytokines IL-6, IL-1β and TNF-α, where BMDM showed increased secretion of these cytokines after LPS + Nigericin stimulation. In addition, changes were observed in the autophagy pathway, where the increase in the autophagic protein LC3b and Beclin-1 occurred by macrophages of non-diabetic animals in hyperglycemic medium, without LPS stimulation. D-BMDM showed a reduction on the expression of LC3b and Beclin-1, suggesting an impaired autophagic process in these cells.

Conclusion

The results suggest that hyperglycemia alters the inflammatory pathways in macrophages stimulated by LPS, playing an important role in the inflammatory response of diabetic individuals.

The DNA adenine methylase of Salmonella Enteritidis promotes their intracellular replication by inhibiting arachidonic acid metabolism pathway in macrophages

Macrophages can participate in immune responses by altering their metabolism, and play important roles in controlling bacterial infections. However, Salmonella Enteritidis can survive and proliferate in macrophages. After the deletion of DNA adenine methylase (Dam), the proliferation of Salmonella Enteritidis in macrophages decreased, the molecular mechanism is still unclear. After infecting macrophages with Salmonella Enteritidis wild type and dam gene deletion strains, intracellular metabolites were extracted and detected by non-targeted metabolomics and fatty acid targeted metabolomics. We found Dam had significant effects on arachidonic acid and related metabolic pathways in macrophages. The dam gene can promote the proliferation of Salmonella Enteritidis in macrophages by inhibiting the metabolic pathway of cytosolic phospholipase A2-mediated arachidonic acid production and conversion to prostaglandin E2 in macrophages, reducing the secretion of the pro-inflammatory factors IL-1β and IL-6. In addition, inhibition of arachidonic acid-related pathways in macrophages by Arachidonyl trifluoromethyl ketone could restore the proliferation of dam gene deletion strains in macrophages. This study explored the role of Dam in the process of Salmonella Enteritidis invading host cells from the perspective of host cell metabolism, and provides new insights into the immune escape mechanism of Salmonella Enteritidis.

Decreased VEGFA alleviates the symptoms of LPS-induced sepsis in a mouse model by inhibiting glycolysis and thereby regulating the polarization of macrophages

The immune imbalance caused by excessive inflammatory reactions is the primary cause of sepsis. Macrophages with M1 and M2 polarization states are important immune cells that regulate the balance of the inflammatory response in sepsis. Encouraging the conversion of macrophages from the M1 to the M2 type is an important strategy for relieving sepsis. Here, we demonstrated the upregulation of vascular endothelial growth factor A (VEGFA) in a mouse model of sepsis. Then, siRNA technology was applied to inhibit the expression of VEGFA in macrophages. Flow cytometry and RT‒qPCR results showed that low expression of VEGFA inhibited LPS-induced M1 polarization of macrophages. Decreased VEGFA was also proven to lower TNF-α, IL-1β, and IL-6 secretion by LPS-induced macrophages. In addition, the effects of knocking down VEGFA on the energy metabolism pattern of macrophages were investigated by glycolysis pressure tests and mitochondrial pressure tests, and VEGFA knockdown reversed the induction of glycolysis in macrophages by LPS. The mitochondrial content and ATP content results also confirmed this finding. After the tail vein of septic mice was injected with macrophages transfected with si-VEGFA, the liver and kidney damage and the pathological conditions of the lung were alleviated. The secretion of TNF-α and IL-6 was decreased, while IL-10 was increased in their serum. Immunohistochemical staining revealed decreased expression of CD86 and increased expression of CD206 in the si-VEGFA group. This study demonstrates that decreased VEGFA inhibits glycolysis and thus inhibits LPS-induced M1 polarization of macrophages, ultimately relieving sepsis.