Metabolism via Arginase or Nitric Oxide Synthase: Two Competing Arginine Pathways in Macrophages

Infiltration by monocytes of the central nervous system and its role in multiple sclerosis: reflections on therapeutic strategies

Mononuclear macrophage infiltration in the central nervous system is a prominent feature of neuroinflammation. Recent studies on the pathogenesis and progression of multiple sclerosis have highlighted the multiple roles of mononuclear macrophages in the neuroinflammatory process. Monocytes play a significant role in neuroinflammation, and managing neuroinflammation by manipulating peripheral monocytes stands out as an effective strategy for the treatment of multiple sclerosis, leading to improved patient outcomes. This review outlines the steps involved in the entry of myeloid monocytes into the central nervous system that are targets for effective intervention: the activation of bone marrow hematopoiesis, migration of monocytes in the blood, and penetration of the blood-brain barrier by monocytes. Finally, we summarize the different monocyte subpopulations and their effects on the central nervous system based on phenotypic differences. As activated microglia resemble monocyte-derived macrophages, it is important to accurately identify the role of monocyte-derived macrophages in disease. Depending on the roles played by monocyte-derived macrophages at different stages of the disease, several of these processes can be interrupted to limit neuroinflammation and improve patient prognosis. Here, we discuss possible strategies to target monocytes in neurological diseases, focusing on three key aspects of monocyte infiltration into the central nervous system, to provide new ideas for the treatment of neurodegenerative diseases.

Reprogramming macrophage metabolism following myocardial infarction: A neglected piece of a therapeutic opportunity

Given the global prevalence of myocardial infarction (MI) as the leading cause of mortality, there is an urgent need to devise novel strategies that target reducing infarct size, accelerating cardiac tissue repair, and preventing detrimental left ventricular (LV) remodeling. Macrophages, as a predominant type of innate immune cells, undergo metabolic reprogramming following MI, resulting in alterations in function and phenotype that significantly impact the progression of MI size and LV remodeling. This article aimed to delineate the characteristics of macrophage metabolites during reprogramming in MI and elucidate their targets and functions in cardioprotection. Furthermore, we summarize the currently proposed regulatory mechanisms of macrophage metabolic reprogramming and identify the regulators derived from endogenous products and natural small molecules. Finally, we discussed the challenges of macrophage metabolic reprogramming in the treatment of MI, with the goal of inspiring further fundamental and clinical research into reprogramming macrophage metabolism and validating its potential therapeutic targets for MI.

The arginine/ornithine binding protein ArgT plays an essential role in Brucella neotomae/Brucella melitensis to prevent intracellular killing and contribute to chronic persistence in the host

Brucella species are facultative intracellular bacterial pathogens that cause the contagious zoonotic disease, brucellosis. Brucella spp. infect a wide range of animals, including livestock, wild animals, and marine mammals. Compared with other invasive bacterial pathogens, partial information is available on the virulence factors of Brucella that enable them to survive in the host. Here, we performed transposon-based random mutagenesis of B. neotomae and identified the arginine/ornithine binding protein, ArgT, as one of the crucial virulence determinants of Brucella. Deleting ArgT from B. neotomae or B. melitensis resulted in its attenuation in macrophages, which was restored upon complementation with an ArgT expression plasmid. We observed that macrophages infected with ΔArgT-B. neotomae produced elevated levels of NO due to the inability of these mutants to deplete the host intracellular arginine through their importer. Furthermore, defective survival of ΔArgT B. neotomae and B. melitensis was observed in the infected mice, which correlated with enhanced NO production in the mice. Our studies revealed that ArgT plays a vital role in preventing intracellular killing and contributes to the chronic persistence of B. neotomae/B. melitensis in the host. This study highlights the essential role of arginine in clearing intracellular infections and the subversion of this host defense mechanism by intracellular pathogens for their chronic persistence.

Metabolomic fingerprinting of milk fever cows: Pre- and postpartum metabolite alterations

BACKGROUND

Milk fever (MF), a metabolic disorder in dairy cows characterized by low blood calcium concentrations postpartum, is well-recognized clinically. However, comprehensive data on the alteration of metabolites associated with this condition remains sparse.

HYPOTHESIS

Delineate serum metabolite profiles and metabolic pathways preceding, coinciding with, and after the onset of MF.

ANIMALS

Twenty-six cows, including 20 healthy cows and 6 cows initially affected by MF. Because of culling, the number of MF-affected cows decreased to 4 at MF week, +4 weeks, and +8 weeks postpartum.

METHODS

A nested case-control longitudinal study was conducted, with blood samples collected at -8 and -4 weeks prepartum, MF week, and +4 and +8 weeks postpartum. Serum analysis utilized direct injection/liquid chromatography/tandem mass spectrometry (DI/LC/MS/MS) techniques.

RESULTS

Key findings included the identification of diverse metabolites such as hexose, amino acids, phosphatidylcholines, lysophosphatidylcholines, and sphingomyelin, which varied between studied groups (P < .05). The most marked metabolic alterations were observed 4 weeks prepartum. In total, 42, 56, 38, 29, and 24 metabolites distinguished the MF group at the respective time points (P < .05). Additionally, 33 metabolic pathways, including amino acid, antioxidant metabolism, fatty acid degradation, and carbohydrate processing, were impacted (P < .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

Metabolic disruptions in dairy cows begin several weeks before the clinical manifestation of MF and persist up to 8 weeks postpartum. These findings emphasize the complexity of MF, extending beyond only hypocalcemia and indicate the necessity for preemptive monitoring in dairy herd management.

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.

Mechanisms of epigenomic and functional convergence between glucocorticoid- and IL4-driven macrophage programming

Macrophages adopt distinct phenotypes in response to environmental cues, with type-2 cytokine interleukin-4 promoting a tissue-repair homeostatic state (M2IL4). Glucocorticoids (GC), widely used anti-inflammatory therapeutics, reportedly impart a similar phenotype (M2GC), but how such disparate pathways may functionally converge is unknown. We show using integrative functional genomics that M2IL4 and M2GC transcriptomes share a striking overlap mirrored by a shift in chromatin landscape in both common and signal-specific gene subsets. This core homeostatic program is enacted by transcriptional effectors KLF4 and the glucocorticoid receptor, whose genome-wide occupancy and actions are integrated in a stimulus-specific manner by the nuclear receptor cofactor GRIP1. Indeed, many of the M2IL4:M2GC-shared transcriptomic changes were GRIP1-dependent. Consistently, GRIP1 loss attenuated phagocytic activity of both populations in vitro and macrophage tissue-repair properties in the murine colitis model in vivo. These findings provide a mechanistic framework for homeostatic macrophage programming by distinct signals, to better inform anti-inflammatory drug design.

Expression of key immune genes in polarized porcine monocyte-derived macrophage subsets

Swine are considered one of the most relevant large animal biomedical models since they share many immunological similarities with humans. Despite that, macrophage polarization has not comprehensively investigated in pigs. In this study, porcine monocyte-derived macrophages (moMΦ) were untreated or stimulated with IFN-γ + LPS (classical activation), or by different M2 polarizing stimuli: IL-4, IL-10, TGF-β, or dexamethasone. Expression of key cytokine genes (IL1B2, IL33, IL19, IL22, IL26, CCL17, CCL24, IFNA, IFNB) in macrophage subsets were investigated over time. Expression of the genes encoding the two main enzymes of the arginine pathway (ARG1, NOS2), and molecules related to alternative macrophage polarization in human and mice (MMP9, MRC1, FIZZ1, VEGFA) were also assessed. Stimulation with IFN-γ + LPS triggered up-regulation of IL1B2, IFNB, NOS2, whereas IL-4 triggered upregulation of CCL17, CCL24, CXCR2, and ARG1 expression. IL19 and IL22 expression was enhanced by stimulation with IFN-γ + LPS or TGF-β, but not IL-4, IL-10, or dexamethasone. Our data highlighted some peculiarities in swine, such as induced expression of IL33 after stimulation with IFN-γ + LPS, and no up-regulation of FIZZ1, VEGFA or MMP9 after exposure to any of the M2 polarizing stimuli. A better understanding of porcine macrophage polarization could benefit translational studies using this large animal model.

Exploring the circulating metabolome of sepsis: metabolomic and lipidomic profiles sampled in the ambulance

BACKGROUND

Sepsis is defined as a dysfunctional host response to infection. The diverse clinical presentations of sepsis pose diagnostic challenges and there is a demand for enhanced diagnostic markers for sepsis as well as an understanding of the underlying pathological mechanisms involved in sepsis. From this perspective, metabolomics has emerged as a potentially valuable tool for aiding in the early identification of sepsis that could highlight key metabolic pathways and underlying pathological mechanisms.

OBJECTIVE

The aim of this investigation is to explore the early metabolomic and lipidomic profiles in a prospective cohort where plasma samples (n = 138) were obtained during ambulance transport among patients with infection according to clinical judgement who subsequently developed sepsis, patients who developed non-septic infection, and symptomatic controls without an infection.

METHODS

Multiplatform metabolomics and lipidomics were performed using UHPLC-MS/MS and UHPLC-QTOFMS. Uni- and multivariable analysis were used to identify metabolite profiles in sepsis vs symptomatic control and sepsis vs non-septic infection.

RESULTS

Univariable analysis disclosed that out of the 457 annotated metabolites measured across three different platforms, 23 polar, 27 semipolar metabolites and 133 molecular lipids exhibited significant differences between patients who developed sepsis and symptomatic controls following correction for multiple testing. Furthermore, 84 metabolites remained significantly different between sepsis and symptomatic controls following adjustment for age, sex, and Charlson comorbidity score. Notably, no significant differences were identified in metabolites levels when comparing patients with sepsis and non-septic infection in univariable and multivariable analyses.

CONCLUSION

Overall, we found that the metabolome, including the lipidome, was decreased in patients experiencing infection and sepsis, with no significant differences between the two conditions. This finding indicates that the observed metabolic profiles are shared between both infection and sepsis, rather than being exclusive to sepsis alone.

A rising star involved in tumour immunity: Lactylation

In recent years, continuous exploration worldwide has revealed that some metabolites produced during cellular and tissue metabolism can act as signalling molecules to exert different effects on the human body. These metabolites may act as cofactors for proteases or as post-translational modifications linked to proteins. Lactate, a traditional metabolite, is found at high levels in the tumour microenvironment (TME). Many studies have shown that lactate influences tumorigenesis and development via different mechanisms, not only through the metabolic reprogramming of tumours but also through its significant impact on tumour immunity. Previously, tumour cells were reported to use glucose and glutamine to fuel lactate metabolism; however, lactate serves not only as an energy source for tumour cells but also as a precursor substance needed for the post-translational modification of proteins. Recent studies identified a novel form of epigenetic modification, lactate-mediated histone lysine lactylation (Kla) and demonstrated that histone lactylation directly stimulates chromatin after gene transcription; consequently, lactylation has become a popular research topic in recent years. This article focuses on the research progress and application prospects of lactylation in the context of tumour immunity.

Inorganic Nanoparticle Functionalization Strategies in Immunotherapeutic Applications

Nanotechnology has been increasingly utilized in anticancer treatment owing to its ability of engineering functional nanocarriers that enhance therapeutic effectiveness while minimizing adverse effects. Inorganic nanoparticles (INPs) are prevalent nanocarriers to be customized for a wide range of anticancer applications, including theranostics, imaging, targeted drug delivery, and therapeutics, because they are advantageous for their superior biocompatibility, unique optical properties, and capacity of being modified via versatile surface functionalization strategies. In the past decades, the high adaptation of INPs in this emerging immunotherapeutic field makes them good carrier options for tumor immunotherapy and combination immunotherapy. Tumor immunotherapy requires targeted delivery of immunomodulating therapeutics to tumor locations or immunological organs to provoke immune cells and induce tumor-specific immune response while regulating immune homeostasis, particularly switching the tumor immunosuppressive microenvironment. This review explores various INP designs and formulations, and their employment in tumor immunotherapy and combination immunotherapy. We also introduce detailed demonstrations of utilizing surface engineering tactics to create multifunctional INPs. The generated INPs demonstrate the abilities of stimulating and enhancing the immune response, specific targeting, and regulating cancer cells, immune cells, and their resident microenvironment, sometimes along with imaging and tracking capabilities, implying their potential in multitasking immunotherapy. Furthermore, we discuss the promises of INP-based combination immunotherapy in tumor treatments.

A Hirsutella sinensis Alcohol Extract Exerts Bidirectional Immunoregulatory Effects by Regulating Macrophage Polarization

For background, Hirsutella sinensis, the only anamorphic fungus considered an effective substitute for Cordyceps sinensis, possesses immunoregulatory properties. However, the specific mechanism underlying the immunoregulatory function of Hirsutella sinensis remains unclear. The purpose is to investigate the therapeutic effects of Hirsutella sinensis alcohol extract (HSAE) on immune dysregulation and elucidate the underlying mechanisms involved. For methods, we established inflammatory and immunosuppression models in vitro and in vivo to evaluate the bidirectional immunoregulatory function of HSAE via qRT-PCR and immunoblotting. We also studied its potential mechanism via RNA sequencing and transcriptional analysis. We further established M1 and M2 cell models to explore the effect of HSAE on M1/M2 polarization using qRT-PCR, immunoblotting, and flow cytometry. For results, our data demonstrated enhanced proliferation, phagocytosis, and antipathogenic activities of macrophages. Treatment with HSAE led to increases in the proportions of CD3+ and CD4+ immune cells in cyclophosphamide-induced immunosuppressed mice. Additionally, HSAE reduced the lipopolysaccharide (LPS)-induced expression of Il1b, Il6, Ifnb1, and Cxcl10 by inhibiting the activation of the NF-κB and MAPK pathways in vitro and improved mouse survival by reducing the proportion of M1/M2 macrophages in septic mice. Finally, we found that HSAE inhibited M1 polarization by decreasing the expression of iNOS and CD86 and promoted M2 polarization by increasing the expression of ARG1 and CD206. For conclusions, our study provides evidence that HSAE has the potential to enhance immune responses and suppress excessive inflammation. These effects were realized by modulating macrophage polarization, providing novel insights into the fundamental mechanism underlying the bidirectional immunomodulatory effect of HSAE.

PPARβ/δ Agonist GW0742 Modulates Microglial and Astroglial Gene Expression in a Rat Model of Temporal Lobe Epilepsy

The role of astroglial and microglial cells in the pathogenesis of epilepsy is currently under active investigation. It has been proposed that the activity of these cells may be regulated by the agonists of peroxisome proliferator-activated nuclear receptors (PPARs). This study investigated the effects of a seven-day treatment with the PPAR β/δ agonist GW0742 (Fitorine, 5 mg/kg/day) on the behavior and gene expression of the astroglial and microglial proteins involved in the regulation of epileptogenesis in the rat brain within a lithium-pilocarpine model of temporal lobe epilepsy (TLE). TLE resulted in decreased social and increased locomotor activity in the rats, increased expression of astro- and microglial activation marker genes (Gfap, Aif1), pro- and anti-inflammatory cytokine genes (Tnfa, Il1b, Il1rn), and altered expression of other microglial (Nlrp3, Arg1) and astroglial (Lcn2, S100a10) genes in the dorsal hippocampus and cerebral cortex. GW0742 attenuated, but did not completely block, some of these impairments. Specifically, the treatment affected Gfap gene expression in the dorsal hippocampus and Aif1 gene expression in the cortex. The GW0742 injections attenuated the TLE-specific enhancement of Nlrp3 and Il1rn gene expression in the cortex. These results suggest that GW0742 may affect the expression of some genes involved in the regulation of epileptogenesis.

Macrophage fate: to kill or not to kill?

Macrophages are dynamic innate immune cells that either reside in tissue, serving as sentinels, or recruited as monocytes from bone marrow into inflamed and infected tissue. In response to cues in the tissue microenvironment (TME), macrophages polarize on a continuum toward M1 or M2 with diverse roles in progression and resolution of disease. M1-like macrophages exhibit proinflammatory functions with antimicrobial and anti-tumorigenic activities, while M2-like macrophages have anti-inflammatory functions that generally resolve inflammatory responses and orchestrate a tissue healing process. Given these opposite phenotypes, proper spatiotemporal coordination of macrophage polarization in response to cues within the TME is critical to effectively resolve infectious disease and regulate wound healing. However, if this spatiotemporal coordination becomes disrupted due to persistent infection or dysregulated coagulation, macrophages' inappropriate response to these cues will result in the development of diseases with clinically unfavorable outcomes. Since plasticity and heterogeneity are hallmarks of macrophages, they are attractive targets for therapies to reprogram toward specific phenotypes that could resolve disease and favor clinical prognosis. In this review, we discuss how basic science studies have elucidated macrophage polarization mechanisms in TMEs during infections and inflammation, particularly coagulation. Therefore, understanding the dynamics of macrophage polarization within TMEs in diseases is important in further development of targeted therapies.

Single-Cell Time-Resolved Metabolomics and Lipidomics Reveal Apoptotic and Ferroptotic Heterogeneity during Foam Cell Formation

Macrophage-derived foam cells play a crucial role in plaque formation and rupture during the progression of atherosclerosis. Traditional studies have often overlooked the heterogeneity of foam cells, focusing instead on populations of cells. To address this, we have developed time-resolved, single-cell metabolomics and lipidomics approaches to explore the heterogeneity of macrophages during foam cell formation. Our dynamic metabolomic and lipidomic analyses revealed a dual regulatory axis involving inflammation and ferroptosis. Further, single-cell metabolomics and lipidomics have delineated a continuum of macrophage states, with varied susceptibilities to apoptosis and ferroptosis. Single-cell transcriptomic profiling confirmed these divergent fates, both in established cell lines and in macrophages derived from peripheral blood monocytes. This research has uncovered the complex molecular interactions that dictate these divergent cell fates, providing crucial insights into the pathogenesis of atherosclerosis.

Triple threat: how diabetes results in worsened bacterial infections

Diabetes mellitus, characterized by impaired insulin signaling, is associated with increased incidence and severity of infections. Various diabetes-related complications contribute to exacerbated bacterial infections, including hyperglycemia, innate immune cell dysfunction, and infection with antibiotic-resistant bacterial strains. One defining symptom of diabetes is hyperglycemia, resulting in elevated blood and tissue glucose concentrations. Glucose is the preferred carbon source of several bacterial pathogens, and hyperglycemia escalates bacterial growth and virulence. Hyperglycemia promotes specific mechanisms of bacterial virulence known to contribute to infection chronicity, including tissue adherence and biofilm formation. Foot infections are a significant source of morbidity in individuals with diabetes and consist of biofilm-associated polymicrobial communities. Bacteria perform complex interspecies behaviors conducive to their growth and virulence within biofilms, including metabolic cross-feeding and altered phenotypes more tolerant to antibiotic therapeutics. Moreover, the metabolic dysfunction caused by diabetes compromises immune cell function, resulting in immune suppression. Impaired insulin signaling induces aberrations in phagocytic cells, which are crucial mediators for controlling and resolving bacterial infections. These aberrancies encompass altered cytokine profiles, the migratory and chemotactic mechanisms of neutrophils, and the metabolic reprogramming required for the oxidative burst and subsequent generation of bactericidal free radicals. Furthermore, the immune suppression caused by diabetes and the polymicrobial nature of the diabetic infection microenvironment may promote the emergence of novel strains of multidrug-resistant bacterial pathogens. This review focuses on the "triple threat" linked to worsened bacterial infections in individuals with diabetes: (i) altered nutritional availability in diabetic tissues, (ii) diabetes-associated immune suppression, and (iii) antibiotic treatment failure.

Pathophysiology of Arginases in Cancer and Efforts in Their Pharmacological Inhibition

Arginases are key enzymes that hydrolyze L-arginine to urea and L-ornithine in the urea cycle. The two arginase isoforms, arginase 1 (ARG1) and arginase 2 (ARG2), regulate the proliferation of cancer cells, migration, and apoptosis; affect immunosuppression; and promote the synthesis of polyamines, leading to the development of cancer. Arginases also compete with nitric oxide synthase (NOS) for L-arginine, and their participation has also been confirmed in cardiovascular diseases, stroke, and inflammation. Due to the fact that arginases play a crucial role in the development of various types of diseases, finding an appropriate candidate to inhibit the activity of these enzymes would be beneficial for the therapy of many human diseases. In this review, based on numerous experimental, preclinical, and clinical studies, we provide a comprehensive overview of the biological and physiological functions of ARG1 and ARG2, their molecular mechanisms of action, and affected metabolic pathways. We summarize the recent clinical trials' advances in targeting arginases and describe potential future drugs.

Transcriptome profiling of macrophages persistently infected with human respiratory syncytial virus and effect of recombinant Taenia solium calreticulin on immune-related genes

Introduction

Human respiratory syncytial virus (hRSV) is a main cause of bronchiolitis in infants and its persistence has been described in immunocompromised subjects. However, limited evidence has been reported on the gene expression triggered by the hRSV and the effect of recombinant Taenia solium-derived calreticulin (rTsCRT).

Methods

Using a comprehensive microarray approach, we analyzed the transcriptome profile of a macrophage cell line that has supported hRSV persistence for over 150 passages. We compared the gene expression of persistently infected and non-infected macrophages. We also evaluated the effect of rTsCRT on hRSV-infected macrophage gene transcription, as well as on cytokine production and number of copies of the persistent hRSV genome.

Results

Our analysis showed that hRSV long-term virus infection significantly alters mRNA expression of antiviral, inflammatory, as well as arginine and lipid metabolism-associated genes, revealing a transcriptional signature that suggests a mixed M1/M2 phenotype. The resulting host-virus equilibrium allows for the regulation of viral replication, while evading the antiviral and proinflammatory responses. Interestingly, rTsCRT stimulus upregulated Tnfα, Il6 and Nos2 mRNA. We found increased levels of both proinflammatory cytokines and nitrite levels in the conditioned media of persistent macrophages treated with rTsCRT. This increase was associated with a significant reduction in viral genome copies.

Discussion

hRSV persistently infected macrophages retain responsiveness to external stimuli and demonstrate that the profound changes induced by viral persistence are potentially reversible. Our observations contribute to the understanding of the mechanisms related to hRSV persistence in macrophages and have implications for the development of targeted therapies to eliminate persistent infections or reduce the negative effects related with chronic inflammatory diseases associated with hRSV infection.

Immunometabolism in atherosclerosis: a new understanding of an old disease

Atherosclerosis, a chronic inflammatory condition, remains a leading cause of death globally, necessitating innovative approaches to target pro-atherogenic pathways. Recent advancements in the field of immunometabolism have highlighted the crucial interplay between metabolic pathways and immune cell function in atherogenic milieus. Macrophages and T cells undergo dynamic metabolic reprogramming to meet the demands of activation and differentiation, influencing plaque progression. Furthermore, metabolic intermediates intricately regulate immune cell responses and atherosclerosis development. Understanding the metabolic control of immune responses in atherosclerosis, known as athero-immunometabolism, offers new avenues for preventive and therapeutic interventions. This review elucidates the emerging intricate interplay between metabolism and immunity in atherosclerosis, underscoring the significance of metabolic enzymes and metabolites as key regulators of disease pathogenesis and therapeutic targets.

Citrulline supplementation exacerbates sepsis severity in infected preterm piglets via early induced immunosuppression

Arginine (ARG)/Citrulline (CIT) deficiency is associated with increased sepsis severity after infection. Supplementation of CIT to susceptible patients with ARG/CIT deficiency such as preterm newborns with suspected infection might prevent sepsis, via maintaining immune and vascular function. Caesarean-delivered, parenterally nourished preterm pigs were treated with CIT (1g/kg bodyweight) via oral or continuous intravenous supplementation, then inoculated with live Staphylococcus epidermidis and clinically monitored for 14 h. Blood, liver, and spleen samples were collected for analysis. In vitro cord blood stimulation was performed to explore how CIT and ARG affect premature blood cell responses. After infection, oral CIT supplementation led to higher mortality, increased blood bacterial load, and systemic and hepatic inflammation. Intravenous CIT administration showed increased inflammation and bacterial burdens without significantly affecting mortality. Liver transcriptomics and data from in vitro blood stimulation indicated that CIT induces systemic immunosuppression in preterm newborns, which may impair resistance response to bacteria at the early stage of infection, subsequently causing later uncontrollable inflammation and tissue damage. The early stage of CIT supplementation exacerbates sepsis severity in infected preterm pigs, likely via inducing systemic immunosuppression.

Metabolic reprogramming of the tumor microenvironment to enhance immunotherapy

Immunotherapy represents a promising treatment strategy for targeting various tumor types. However, the overall response rate is low due to the tumor microenvironment (TME). In the TME, numerous distinct factors actively induce immunosuppression, restricting the efficacy of anticancer immune reactions. Recently, metabolic reprogramming of tumors has been recognized for its role in modulating the tumor microenvironment to enhance immune cell responses in the TME. Furthermore, recent elucidations underscore the critical role of metabolic limitations imposed by the tumor microenvironment on the effectiveness of antitumor immune cells, guiding the development of novel immunotherapeutic approaches. Hence, achieving a comprehensive understanding of the metabolic requirements of both cancer and immune cells within the TME is pivotal. This insight not only aids in acknowledging the current limitations of clinical practices but also significantly shapes the trajectory of future research endeavors in the domain of cancer immunotherapy. In addition, therapeutic interventions targeting metabolic limitations have exhibited promising potential as combinatory treatments across diverse cancer types. In this review, we first discuss the metabolic barriers in the TME. Second, we explore how the immune response is regulated by metabolites. Finally, we will review the current strategy for targeting metabolism to not simply inhibit tumor growth but also enhance antitumor immune responses. Thus, we could suggest potent combination therapy for improving immunotherapy with metabolic inhibitors. [BMB Reports 2024; 57(9): 388-399].

Metabolic reprogramming in septic acute kidney injury: pathogenesis and therapeutic implications

Acute kidney injury (AKI) is a frequent and severe complication of sepsis and is characterized by significant mortality and morbidity. However, the pathogenesis of septic acute kidney injury (S-AKI) remains elusive. Metabolic reprogramming, which was originally referred to as the Warburg effect in cancer, is strongly related to S-AKI. At the onset of sepsis, both inflammatory cells and renal parenchymal cells, such as macrophages, neutrophils and renal tubular epithelial cells, undergo metabolic shifts toward aerobic glycolysis to amplify proinflammatory responses and fortify cellular resilience to septic stimuli. As the disease progresses, these cells revert to oxidative phosphorylation, thus promoting anti-inflammatory reactions and enhancing functional restoration. Alterations in mitochondrial dynamics and metabolic reprogramming are central to the energetic changes that occur during S-AKI. In this review, we summarize the current understanding of the pathogenesis of metabolic reprogramming in S-AKI, with a focus on each cell type involved. By identifying relevant key regulatory factors, we also explored potential metabolic reprogramming-related therapeutic targets for the management of S-AKI.

Macrophage energy metabolism in cardiometabolic disease

In a rapidly expanding body of literature, the major role of energy metabolism in determining the response and polarization status of macrophages has been examined, and it is currently a very active area of research. The metabolic flux through different metabolic pathways in the macrophage is interconnected and complex and could influence the polarization of macrophages. Earlier studies suggested glucose flux through cytosolic glycolysis is a prerequisite to trigger the pro-inflammatory phenotypes of macrophages while proposing that fatty acid oxidation is essential to support anti-inflammatory responses by macrophages. However, recent studies have shown that this understanding is oversimplified and that the metabolic control of macrophage polarization is highly complex and not fully defined yet. In this review, we systematically reviewed and summarized the literature regarding the role of energy metabolism in controlling macrophage activity and how that might be altered in cardiometabolic diseases, namely heart failure, obesity, and diabetes. We critically appraised the experimental studies and methodologies in the published studies. We also highlighted the challenging concepts in macrophage metabolism and identified several research questions yet to be addressed in future investigations.

Tumor microenvironment induced switch to mitochondrial metabolism promotes suppressive functions in immune cells

Understanding the intricacies of the metabolic phenotype in immune cells and its plasticity within the tumor microenvironment is pivotal in understanding the pathology and prognosis of cancer. Unfavorable conditions and cellular stress in the tumor microenvironment (TME) exert a profound impact on cellular functions in immune cells, thereby influencing both tumor progression and immune responses. Elevated AMP:ATP ratio, a consequence of limited glucose levels, activate AMP-activated protein kinase (AMPK) while concurrently repressing the activity of mechanistic target of rapamycin (mTOR) and hypoxia-inducible factor 1-alpha (HIF-1α). The intricate balance between AMPK, mTOR, and HIF-1α activities defines the metabolic phenotype of immune cells in the TME. These Changes in metabolic phenotype are strongly associated with immune cell functions and play a crucial role in creating a milieu conducive to tumor progression. Insufficiency of nutrient and oxygen supply leads to a metabolic shift in immune cells characterized by a decrease in glycolysis and an increase in oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) rates. In most cases, this shift in metabolism is accompanied by a compromise in the effector functions of these immune cells. This metabolic adaptation prompts immune cells to turn down their effector functions, entering a quiescent or immunosuppressive state that may support tumor growth. This article discusses how tumor microenvironment alters the metabolism in immune cells leading to their tolerance and tumor progression, with emphasis on mitochondrial metabolism (OXPHOS and FAO).

Citrulline and ADI-PEG20 reduce inflammation in a juvenile porcine model of acute endotoxemia

Background

Arginine is a conditionally essential amino acid that is depleted in critically ill or surgical patients. In pediatric and adult patients, sepsis results in an arginine-deficient state, and the depletion of plasma arginine is associated with greater mortality. However, direct supplementation of arginine can result in the excessive production of nitric oxide (NO), which can contribute to the hypotension and macrovascular hypo-reactivity observed in septic shock. Pegylated arginine deiminase (ADI-PEG20, pegargiminase) reduces plasma arginine and generates citrulline that can be transported intracellularly to generate local arginine and NO, without resulting in hypotension, while maintaining microvascular patency. The objective of this study was to assess the efficacy of ADI-PEG20 with and without supplemental intravenous citrulline in mitigating hypovolemic shock, maintaining tissue levels of arginine, and reducing systemic inflammation in an endotoxemic pediatric pig model.

Methods

Twenty 3-week-old crossbred piglets were implanted with jugular and carotid catheters as well as telemetry devices in the femoral artery to measure blood pressure, body temperature, heart rate, and respiration rate. The piglets were assigned to one of three treatments before undergoing a 5 h lipopolysaccharide (LPS) infusion protocol. Twenty-four hours before LPS infusion, control pigs (LPS; n=6) received saline, ADI-PEG20 pigs (n=7) received an injection of ADI-PEG20, and seven pigs (ADI-PEG20 + CIT pigs [n=7]) received ADI-PEG20 and 250 mg/kg citrulline intravenously. Pigs were monitored throughout LPS infusion and tissue was harvested at the end of the protocol.

Results

Plasma arginine levels decreased and remained low in ADI-PEG20 + CIT and ADI-PEG20 pigs compared with LPS pigs but tissue arginine levels in the liver and kidney were similar across all treatments. Mean arterial pressure in all groups decreased from 90 mmHg to 60 mmHg within 1 h of LPS infusion but there were no significant differences between treatment groups. ADI-PEG20 and ADI-PEG20 + CIT pigs had less CD45+ infiltrate in the liver and lung and lower levels of pro-inflammatory cytokines in the plasma.

Conclusion

ADI-PEG20 and citrulline supplementation failed to ameliorate the hypotension associated with acute endotoxic sepsis in pigs but reduced systemic and local inflammation in the lung and liver.

Pharmacological potential of 4-dimethylamino chalcone against acute and neuropathic pain in mice

OBJECTIVES

This work investigated the acute antinociceptive effect of a synthetic chalcone, 4-dimethylamino chalcone (DMAC), as well as its effects on vincristine-induced peripheral neuropathy (VIPN) in mice.

METHODS

The inhibitory activity of myeloperoxidase was assessed by measuring HOCl formation. Formalin and hot plate tests were used to study the acute antinociceptive effect of DMAC. VIPN was induced through the administration of vincristine sulphate (0.1 mg/kg, i.p., 14 days). Then, DMSO, DMAC (10 or 30 mg/kg; i.p.), or pregabalin (10 mg/kg, i.p.) were administered for 14 consecutive days. Thermal hyperalgesia and mechanical allodynia were evaluated before and after VIPN induction and on days 1, 3, 7, and 14 of treatment. Neurodegeneration and neuroinflammation were assessed through immunohistochemistry for NF200, iNOS, and arginase-1 within the sciatic nerve.

KEY FINDINGS

DMAC inhibited myeloperoxidase activity in vitro and presented an acute antinociceptive effect in both formalin and hot plate tests, with the involvement of muscarinic and opioid receptors. Treatment with 30 mg/kg of DMAC significantly attenuated thermal hyperalgesia and mechanical allodynia and prevented macrophage proinflammatory polarisation in VIPN mice.

CONCLUSIONS

Our results show that DMAC, acting through different mechanisms, effectively attenuates VIPN.

How does Nogo-A signalling influence mitochondrial function during multiple sclerosis pathogenesis?

Multiple sclerosis (MS) is a severe neurological disorder that involves inflammation in the brain, spinal cord and optic nerve with key disabling neuropathological outcomes being axonal damage and demyelination. When degeneration of the axo-glial union occurs, a consequence of inflammatory damage to central nervous system (CNS) myelin, dystrophy and death can lead to large membranous structures from dead oligodendrocytes and degenerative myelin deposited in the extracellular milieu. For the first time, this review covers mitochondrial mechanisms that may be operative during MS-related neurodegenerative changes directly activated during accumulating extracellular deposits of myelin associated inhibitory factors (MAIFs), that include the potent inhibitor of neurite outgrowth, Nogo-A. Axonal damage may occur when Nogo-A binds to and signals through its cognate receptor, NgR1, a multimeric complex, to initially stall axonal transport and limit the delivery of important growth-dependent cargo and subcellular organelles such as mitochondria for metabolic efficiency at sites of axo-glial disintegration as a consequence of inflammation. Metabolic efficiency in axons fails during active demyelination and progressive neurodegeneration, preceded by stalled transport of functional mitochondria to fuel axo-glial integrity.

Low-dose dimethylfumarate attenuates colitis-associated cancer in mice through M2 macrophage polarization and blocking oxidative stress

Colitis-associated cancer (CAC) is an aggressive subtype of colorectal cancer that can develop in ulcerative colitis patients and is driven by chronic inflammation and oxidative stress. Current chemotherapy for CAC, based on 5-fluorouracil and oxalipltin, is not fully effective and displays severe side effects, prompting the search for alternative therapies. Dimethylfumarate (DMF), an activator of the nuclear factor erythroid 2-related factor 2 (NRF2), is a potent antioxidant and immunomodelatrory drug used in the treatment of multiple sclerosis and showed a strong anti-inflammatory effect on experimental colitis. Here, we investigated the chemotherapeutic effect of DMF on an experimental model of CAC. Male NMRI mice were given two subcutaneous injections of 1,2 Dimethylhydrazine (DMH), followed by three cycles of dextran sulfate sodium (DSS). Low-dose (DMF30) and high-dose of DMF (DMF100) or oxaliplatin (OXA) were administered from the 8th to 12th week of the experiment, and then the colon tissues were analysed histologically and biochemically. DMH/DSS induced dysplastic aberrant crypt foci (ACF), oxidative stress, and severe colonic inflammation, with a predominance of pro-inflammatory M1 macrophages. As OXA, DMF30 reduced ACF multiplicity and crypt dysplasia, but further restored redox status, and reduced colitis severity by shifting macrophages towards the anti-inflammatory M2 phenotype. Surprisingly, DMF100 exacerbated ACF multiplicity, oxidative stress, and colon inflammation, likely through NRF2 and p53 overexpression in colonic inflammatory cells. DMF had a dual effect on CAC. At low dose, DMF is chemotherapeutic and acts as an antioxidant and immunomodulator, whereas at high dose, DMF is pro-oxidant and exacerbates colitis-associated cancer.

The role of polyamine metabolism in cellular function and physiology

Polyamines are molecules with multiple amino groups that are essential for cellular function. The major polyamines are putrescine, spermidine, spermine, and cadaverine. Polyamines are important for posttranscriptional regulation, autophagy, programmed cell death, proliferation, redox homeostasis, and ion channel function. Their levels are tightly controlled. High levels of polyamines are associated with proliferative pathologies such as cancer, whereas low polyamine levels are observed in aging, and elevated polyamine turnover enhances oxidative stress. Polyamine metabolism is implicated in several pathophysiological processes in the nervous, immune, and cardiovascular systems. Currently, manipulating polyamine levels is under investigation as a potential preventive treatment for several pathologies, including aging, ischemia/reperfusion injury, pulmonary hypertension, and cancer. Although polyamines have been implicated in many intracellular mechanisms, our understanding of these processes remains incomplete and is a topic of ongoing investigation. Here, we discuss the regulation and cellular functions of polyamines, their role in physiology and pathology, and emphasize the current gaps in knowledge and potential future research directions.

Citric Acid: A Nexus Between Cellular Mechanisms and Biomaterial Innovations

Citrate-based biodegradable polymers have emerged as a distinctive biomaterial platform with tremendous potential for diverse medical applications. By harnessing their versatile chemistry, these polymers exhibit a wide range of material and bioactive properties, enabling them to regulate cell metabolism and stem cell differentiation through energy metabolism, metabonegenesis, angiogenesis, and immunomodulation. Moreover, the recent US Food and Drug Administration (FDA) clearance of the biodegradable poly(octamethylene citrate) (POC)/hydroxyapatite-based orthopedic fixation devices represents a translational research milestone for biomaterial science. POC joins a short list of biodegradable synthetic polymers that have ever been authorized by the FDA for use in humans. The clinical success of POC has sparked enthusiasm and accelerated the development of next-generation citrate-based biomaterials. This review presents a comprehensive, forward-thinking discussion on the pivotal role of citrate chemistry and metabolism in various tissue regeneration and on the development of functional citrate-based metabotissugenic biomaterials for regenerative engineering applications.

Biofilm Production and Its Implications in Pediatrics

Biofilms, aggregates of bacteria enclosed in a self-produced matrix, have been implicated in various pediatric respiratory infections, including acute otitis media (AOM), otitis media with effusion (OME), adenoiditis, protracted bacterial bronchitis, and pulmonary exacerbations in cystic fibrosis. These infections are prevalent in children and often associated with biofilm-producing pathogens, leading to recurrent and chronic conditions. Biofilms reduce antibiotic efficacy, contributing to treatment failure and disease persistence. This narrative review discusses biofilm production by respiratory pathogens such as Streptococcus pneumoniae, non-typeable Haemophilus influenzae, Pseudomonas aeruginosa, and Staphylococcus aureus. It examines their mechanisms of biofilm formation, antibiotic resistance, and the challenges they present in clinical treatment. Various antibiofilm strategies have shown promise in vitro and in animal studies, including the use of N-acetylcysteine, enzymes like dispersin B, and agents disrupting quorum sensing and biofilm matrix components. However, their clinical application, particularly in children, remains limited. Traditional treatments for biofilm-associated diseases have not significantly evolved, even with biofilm detection. The transition from experimental findings to clinical practice is complex and requires robust clinical trials and standardized biofilm detection protocols. Addressing biofilms in pediatric respiratory infections is crucial for improving treatment outcomes and managing recurrent and chronic diseases effectively.

Sugar and arginine facilitate oral tolerance by ensuring the functionality of tolerogenic immune cell subsets in the intestine

Although oral tolerance is a critical system in regulating allergic disorders, the mechanisms by which dietary factors regulate the induction and maintenance of oral tolerance remain unclear. To address this, we explored the differentiation and function of various immune cells in the intestinal immune system under fasting and ad libitum-fed conditions before oral ovalbumin (OVA) administration. Fasting mitigated OVA-specific Treg expansion, which is essential for oral tolerance induction. This abnormality mainly resulted from functional defects in the CX3CR1+ cells responsible for the uptake of luminal OVA and reduction of tolerogenic CD103+ dendritic cells. Eventually, fasting impaired the preventive effect of oral OVA administration on asthma and allergic rhinitis development. Specific food ingredients, namely carbohydrates and arginine, were indispensable for oral tolerance induction by activating glycolysis and mTOR signaling. Overall, prior food intake and nutritional signals are critical for maintaining immune homeostasis by inducing tolerance to ingested food antigens.

RBM15 activates glycolysis in M1-type macrophages to promote the progression of aortic aneurysm and dissection

Aortic aneurysm and dissection (AD) represent a critical cardiovascular emergency with an alarmingly high mortality rate. Recent research has spotlighted the overexpression of genes associated with the m6A modification in AD patients, linking them to the presence of inflammatory M1-type macrophages. Moreover, glycolysis is widely recognized as a key feature of inflammatory M1-type macrophages, but biomarkers linking glycolysis and macrophage function to promote disease progression in AD have not been reported. We conducted an analysis of aortic immune cell infiltration, macrophages, and m6A-related biomarkers in AD patients using bioinformatics techniques. Subsequently, we employed a combination of RT-PCR, WB, and immunofluorescence assays to elucidate the alterations in the expression of M1- and M2-type macrophages, as well as markers of glycolysis, following the overexpression of key biomarkers. These findings were further validated in vivo through the creation of a rat model of AD with knockdown of the aforementioned key biomarkers. The findings revealed that the m6A-modified related gene RBM15 exhibited heightened expression in AD samples and was correlated with macrophage polarization. Upon overexpression of RBM15 in macrophages, there was an observed increase in the expression of M1-type macrophage markers CXCL9 and CXCL10, alongside a decrease in the expression of M2-type macrophage markers CCL13 and MRC1. Furthermore, there was an elevation in the expression of glycolytic enzymes GLUT1 and Hexokinase, as well as HIF1α, GAPDH, and PFKFB3 after RBM15 overexpression. Moreover, in vivo knockdown of RBM15 led to an amelioration of aortic aneurysm in the rat AD model. This knockdown also resulted in a reduction of the M1-type macrophage marker iNOS, while significantly increasing the expression of the M2-type macrophage marker CD206. In conclusion, our findings demonstrate that RBM15 upregulates glycolysis in macrophages, thus contributing to the progression of AD through the promotion of M1-type macrophage polarization. Conversely, downregulation of RBM15 suppresses M1-type macrophage polarization, thereby decelerating the advancement of AD. These results unveil potential novel targets for the treatment of AD.

Fat Phagocytosis Promotes Anti-Inflammatory Responses of Macrophages in a Mouse Model of Osteonecrosis

Osteonecrosis (ON) of the femoral head (ONFH) is a devastating bone disease affecting over 20 million people worldwide. ONFH is caused by a disruption of the blood supply, leading to necrotic cell death and increased inflammation. Macrophages are the key cells mediating the inflammatory responses in ON. It is unclear what the dynamic phenotypes of macrophages are and what mechanisms may affect macrophage polarization and, therefore, the healing process. In our preliminary study, we found that there is an invasion of macrophages into the repair tissue during ON healing. Interestingly, in both ONFH patients and a mouse ON model, fat was co-labeled within macrophages using immunofluorescence staining, indicating the phagocytosis of fat by macrophages. To study the effects of fat phagocytosis on the macrophage phenotype, we set up an in vitro macrophage and fat co-culture system. We found that fat phagocytosis significantly decreased M1 marker expression, such as IL1β and iNOS, in macrophages, whereas the expression of the M2 marker Arg1 was significantly increased with fat phagocytosis. To investigate whether the polarization change is indeed mediated by phagocytosis, we treated the cells with Latrunculin A (LA, which inhibits actin polymerization and phagocytosis). LA supplementation significantly reversed the polarization marker gene changes induced by fat phagocytosis. To provide an unbiased transcriptional gene analysis, we submitted the RNA for bulk RNA sequencing. Differential gene expression (DGE) analysis revealed that the top upregulated genes were related to anti-inflammatory responses, while proinflammatory genes were significantly downregulated. Additionally, using pathway enrichment and network analyses (Metascape), we confirmed that gene-enriched categories related to proinflammatory responses were significantly downregulated in macrophages with fat phagocytosis. Finally, we validated the similar macrophage phenotype changes in vivo. To summarize, we discovered that fat phagocytosis occurs in both ONFH patients and an ON mouse model, which inhibits proinflammatory responses with increased anabolic gene expression in macrophages. This fat-phagocytosis-induced macrophage phenotype is consistent with the in vivo changes shown in the ON mouse model. Our study reveals a novel phagocytosis-mediated macrophage polarization mechanism in ON, which fills in our knowledge gaps of macrophage functions and provides new concepts in macrophage immunomodulation as a promising treatment for ON.

PI3K/AKT signaling alters glucose metabolism in uterine microenvironment of women with idiopathic recurrent spontaneous miscarriage

BACKGROUND

This study aims to identify metabolomic signatures in uterine fluid of women with idiopathic recurrent spontaneous miscarriage (IRSM) during window of implantation (WOI). Also, glucose transporters GLUT3 and GLUT4 and proteins of PI3K-Akt signaling pathway in endometrial tissue are assessed.

METHODS

Paired uterine fluid and endometrial biopsies were collected during WOI from women with IRSM (n = 24) and healthy women with azoospermic male partners as controls (n = 15). NMR metabolomics was used to identify the dysregulated metabolites in uterine fluid of IRSM women. Additionally, proteins and glucose transporters were investigated in the endometrial tissue using immunohistochemistry (IHC) and western blotting.

RESULTS

Uterine fluid metabolomics indicated eleven metabolites to be significantly downregulated in IRSM. While expression levels of PI3K (p85), PI3K (p110), p-Akt (Thr308), p-Akt (Ser473), GLUT3 and GLUT4 were significantly downregulated in endometrial tissue of these women, p-IKK α/β (Ser176/180) and p-NFkBp65 (Ser536) were significantly increased.

CONCLUSION

Our findings suggest that dysregulation of PI3K/Akt pathway in the uterine microenvironment could be a likely cause of endometrial dysfunction, thereby affecting implantation. Further studies on the downstream effects of the Akt signaling pathway in-vitro for improved understanding of the Akt-mediated cellular responses in IRSM is, therefore, warranted.

Nanomaterial-Based Repurposing of Macrophage Metabolism and Its Applications

Macrophage immunotherapy represents an emerging therapeutic approach aimed at modulating the immune response to alleviate disease symptoms. Nanomaterials (NMs) have been engineered to monitor macrophage metabolism, enabling the evaluation of disease progression and the replication of intricate physiological signal patterns. They achieve this either directly or by delivering regulatory signals, thereby mapping phenotype to effector functions through metabolic repurposing to customize macrophage fate for therapy. However, a comprehensive summary regarding NM-mediated macrophage visualization and coordinated metabolic rewiring to maintain phenotypic equilibrium is currently lacking. This review aims to address this gap by outlining recent advancements in NM-based metabolic immunotherapy. We initially explore the relationship between metabolism, polarization, and disease, before delving into recent NM innovations that visualize macrophage activity to elucidate disease onset and fine-tune its fate through metabolic remodeling for macrophage-centered immunotherapy. Finally, we discuss the prospects and challenges of NM-mediated metabolic immunotherapy, aiming to accelerate clinical translation. We anticipate that this review will serve as a valuable reference for researchers seeking to leverage novel metabolic intervention-matched immunomodulators in macrophages or other fields of immune engineering.

Icariin attenuates asthmatic airway inflammation via modulating alveolar macrophage activation based on network pharmacology and in vivo experiments

BACKGROUND

Icariin (ICA) inhibits inflammatory response in various diseases, but the mechanism underlying ICA treating airway inflammation in asthma needs further understood. We aimed to predict and validate the potential targets of ICA against asthma-associated airway inflammation using network pharmacology and experiments.

METHODS

The ovalbumin-induced asthma-associated airway inflammation mice model was established. The effects of ICA were evaluated by behavioral, airway hyperresponsiveness, lung pathological changes, inflammatory cell and cytokines counts. Next, the corresponding targets of ICA were mined via the SEA, CTD, HERB, PharmMapper, Symmap database and the literature. Pubmed-Gene and GeneCards databases were used to screen asthma and airway inflammation-related targets. The overlapping targets were used to build an interaction network, analyze gene ontology and enrich pathways. Subsequently, flow cytometry, quantitative real-time PCR and western blotting were employed for validation.

RESULTS

ICA alleviated the airway inflammation of asthma; 402 targets of ICA, 5136 targets of asthma and 4531 targets of airway inflammation were screened; 216 overlapping targets were matched and predicted ICA possesses the potential to modulate asthmatic airway inflammation by macrophage activation/polarization. Additionally, ICA decreased M1 but elevated M2. Potential targets that were disrupted by asthma inflammation were restored by ICA treatment.

CONCLUSIONS

ICA alleviates airway inflammation in asthma by inhibiting the M1 polarization of alveolar macrophages, which is related to metabolic reprogramming. Jun, Jak2, Syk, Tnf, Aldh2, Aldh9a1, Nos1, Nos2 and Nos3 represent potential targets of therapeutic intervention. The present study enhances understanding of the anti-airway inflammation effects of ICA, especially in asthma.

MicroRNA expression profile of chicken liver at different times after Histomonas meleagridis infection

Histomonas meleagridis, an anaerobic intercellular parasite, is known to infect gallinaceous birds, particularly turkeys and chickens. The resurgence of histomonosis in recent times has resulted in significant financial setbacks due to the prohibition of drugs used for disease treatment. Currently, research on about H. meleagridis primarily concentrate on the examination of its virulence, gene expression analysis, and the innate immunity response of the host organism. However, there is a lack of research on differentially expressed miRNAs (DEMs) related to liver infection induced by H. meleagridis. In this study, the weight gain and pathological changes at various post-infection time points were evaluated through animal experiments to determine the peak and early stages of infection. Next, High-throughput sequencing was used to examine the expression profile of liver miRNA at 10 and 15 days post-infection (DPI) in chickens infected with the Chinese JSYZ-F strain of H. meleagridis. A comparison with uninfected controls revealed the presence of 120 and 118 DEMs in the liver of infected chickens at 10 DPI and 15 DPI, respectively, with 74 DEMs being shared between the two time points. Differentially expressed microRNAs (DEMs) were categorized into three groups based on the time post-infection. The first group (L1) includes 45 miRNAs that were differentially expressed only at 10 DPI and were predicted to target 1646 genes. The second group (L2) includes 43 miRNAs that were differentially expressed only at 15 DPI and were predicted to target 2257 genes. The third group (L3) includes 75 miRNAs that were differentially expressed at both 10 DPI and 15 DPI and were predicted to target 1623 genes. At L1, L2, and L3, there were 89, 87, and 41 significantly enriched Gene Ontology (GO) terms, respectively (p<0.05). The analysis of differentially expressed miRNA target genes using KEGG pathways revealed significant enrichment at L1, L2, and L3, with 3, 4, and 5 pathways identified, respectively (p<0.05). This article suggests that the expression of liver miRNA undergoes dynamic alterations due to H. meleagridis and the host. It showed that the expression pattern of L1 class DEMs was more conducive to regulating the development of the inflammatory response, while the L2 class DEMs were more conducive to augmenting the inflammatory response. The observed patterns of miRNA expression associated with inflammation were in line with the liver's inflammatory process following infection. The results of this study provide a basis for conducting a comprehensive analysis of the pathogenic mechanism of H. meleagridis from the perspective of host miRNAs.

Metabolic flux in macrophages in obesity and type-2 diabetes

Recent literature extensively investigates the crucial role of energy metabolism in determining the inflammatory response and polarization status of macrophages. This rapidly expanding area of research highlights the importance of understanding the link between energy metabolism and macrophage function. The metabolic pathways in macrophages are intricate and interdependent, and they can affect the polarization of macrophages. Previous studies suggested that glucose flux through cytosolic glycolysis is necessary to trigger pro-inflammatory phenotypes of macrophages, and fatty acid oxidation is crucial to support anti-inflammatory responses. However, recent studies demonstrated that this understanding is oversimplified and that the metabolic control of macrophage polarization is highly complex and not fully understood yet. How the metabolic flux through different metabolic pathways (glycolysis, glucose oxidation, fatty acid oxidation, ketone oxidation, and amino acid oxidation) is altered by obesity- and type 2 diabetes (T2D)-associated insulin resistance is also not fully defined. This mini-review focuses on the impact of insulin resistance in obesity and T2D on the metabolic flux through the main metabolic pathways in macrophages, which might be linked to changes in their inflammatory responses. We closely evaluated the experimental studies and methodologies used in the published research and highlighted priority research areas for future investigations.

Quo vadis ureagenesis disorders? A journey from 90 years ago into the future

The pathway of ammonia disposal in the mammalian organism has been described in 1932 as a metabolic cycle present in the liver in different compartments. In 1958, the first human disorder affecting this pathway was described as a genetic condition leading to cognitive impairment and constant abnormalities of amino acid metabolism. Since then, defects in all enzymes and transporters of the urea cycle have been described, referring to them as primary urea cycle disorders causing primary hyperammonemia. In addition, there is a still increasing list of conditions that impact on the function of the urea cycle by various mechanisms, hereby leading to secondary hyperammonemia. Despite great advances in understanding the molecular background and the biochemical specificities of both primary and secondary hyperammonemias, there remain many open questions: we do not fully understand the pathophysiology in many of the conditions; we do not always understand the highly variable clinical course of affected patients; we clearly appreciate the need for novel and improved diagnostic and therapeutic approaches. This study does look back to the beginning of the urea cycle (hi)story, briefly describes the journey through past decades, hereby illustrating advancements and knowledge gaps, and gives examples for the extremely broad perspective imminent to some of the defects of ureagenesis and allied conditions.

Tumor-Targeting Multiple Metabolic Regulations for Bursting Antitumor Efficacy of Chemodynamic Therapy

Interfering with intratumoral metabolic processes is proven to effectively sensitize different antitumor treatments. Here, a tumor-targeting catalytic nanoplatform (CQ@MIL-GOX@PB) loading with autophagy inhibitor (chloroquine, CQ) and glucose oxidase (GOX) is fabricated to interfere with the metabolisms of tumor cells and tumor-associated macrophages (TAMs), then realizing effective antitumor chemodynamic therapy (CDT). Once accumulating in the tumor site with the navigation of external biotin, CQ@MIL-GOX@PB will release Fe ions and CQ in the acid lysosomes of tumor cells, the latter can sensitize Fe ions-involved antitumor CDT by blocking the autophagy-dependent cell repair. Meanwhile, the GOX component will consume glucose, which not only generates many H2O2 for CDT but also once again decelerates the tumor repair process by reducing energy metabolism. What is more, the release of CQ can also drive the NO anabolism of TAMs to further sensitize CDT. This strategy of multiple metabolic regulations is evidenced to significantly improve the antitumor effect of traditional CDT nanoagents and might provide a new sight to overcome the bottlenecks of different antitumor treatments.

Laminin-derived peptide, IKVAV, modulates macrophage phenotype through integrin mediation

Macrophages are highly plastic immune cells known to exist on a spectrum of phenotypes including pro-inflammatory (M1) or pro-healing (M2). Macrophages interact with extracellular matrix (ECM) ligands, such as fragments of collagen and laminin. Interaction of macrophages with ECM ligands is mediated through integrin receptors. However, the role of ECM ligands in directing macrophage function through integrins is not yet fully understood. Particularly, α2β1 has been implicated in modulating macrophage function, but complexity in mechanisms employed for integrin-ligation especially with laminin-derived peptides makes it challenging to understand macrophage-ECM interactions. We hypothesize that targeting α2β1 through laminin-derived peptide, IKVAV, will modulate macrophage phenotype. In this work we: i) investigated macrophage response to IKVAV in 2D and in a 3D platform, and ii) identified α2β1's role as it pertains to macrophage modulation via IKVAV. Soluble IKVAV treatment significantly reduced M1 markers and increased M2 markers via immunocytochemistry and gene expression. While the 3D ECM-mimicking PEG-IKVAV hydrogels did not have significant effects in modulating macrophage phenotype, we found that macrophage modulation via IKVAV is dependent on the concentration of peptide used and duration of exposure. To investigate integrin-ligand interactions for macrophages, α2β1 signaling was modulated by antagonists and agonists. We observed that blocking α2β1 reduces M1 activation. To understand integrin-ligand interactions and leveraging the therapeutic ability of macrophages in designing immunomodulatory solutions, it is critical to elucidate IKVAV's role in mediating macrophage phenotype.

LncRNA CRNDE promotes hepatoma cell proliferation by regulating the metabolic reprogramming of M2 macrophages via ERK pathway

BACKGROUND

LncRNA colorectal neoplasia differentially expressed (CRNDE) was found to be an important regulator in many cancers. This project focuses on the function of CRNDE on macrophage metabolic reprogramming and Hepatocellular carcinoma (HCC).

METHOD

qRT-PCR and Immunofluorescence were used to analyze Arg-1, IL-10, CD163, CCL-18, CD206, and CRNDE expression in HCC tissues and macrophages. Western Blotting was used to analyze ERK and p-ERK expression. Edu assay, transwell assay and xenograft experiments were carried out to study cell viability, migrated and invasive capability. Immunohistochemical staining was used to evaluate Ki67 expression. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed for macrophages metabolites analysis.

RESULTS

Arg-1, IL-10, CD163, CD206, and CRNDE were significantly up-regulated in HCC tissues, M2 macrophage and M0 macrophage with CRNDE overexpressed (OV-CRNDE-M0), which downregulated in M0 macrophage with CRNDE knockdown (sh-CRNDE-M0). The conditioned medium (CM) of M2 cells and OV-CRNDE-M0 cells promoted cell viability, invasion, and migration of HCC cells, the effect was reversed by sh-CRNDE-M0 cells CM. OV-CRNDE-M0 cells promoted tumor growth, Ki67 and CD206 expression in xenograft model. 61 metabolites were detected, of which 18 metabolites changed significantly in OV-CRNDE-M0 group compared to M0 group, with 9 upregulated and 9 downregulated. KEGG analysis showed the enrichment pathways were biosynthesis, glyoxylate and dicarboxylate metabolism. SMPDB analysis showed the enrichment pathways were hypoacetylaspartia, canavan disease, and aspartate metabolism.

CONCLUSION

CRNDE regulated the metabolic reprogramming of M2 macrophage via ERK pathway, which thereby contributed to HCC proliferation, migration, and invasion.

Neither injury induced macrophages within the nerve, nor the environment created by Wallerian degeneration is necessary for enhanced in vivo axon regeneration after peripheral nerve injury

BACKGROUND

Since the 1990s, evidence has accumulated that macrophages promote peripheral nerve regeneration and are required for enhancing regeneration in the conditioning lesion (CL) response. After a sciatic nerve injury, macrophages accumulate in the injury site, the nerve distal to that site, and the axotomized dorsal root ganglia (DRGs). In the peripheral nervous system, as in other tissues, the macrophage response is derived from both resident macrophages and recruited monocyte-derived macrophages (MDMs). Unresolved questions are: at which sites do macrophages enhance nerve regeneration, and is a particular population needed.

METHODS

Ccr2 knock-out (KO) and Ccr2gfp/gfp knock-in/KO mice were used to prevent MDM recruitment. Using these strains in a sciatic CL paradigm, we examined the necessity of MDMs and residents for CL-enhanced regeneration in vivo and characterized injury-induced nerve inflammation. CL paradigm variants, including the addition of pharmacological macrophage depletion methods, tested the role of various macrophage populations in initiating or sustaining the CL response. In vivo regeneration, measured from bilateral proximal test lesions (TLs) after 2 d, and macrophages were quantified by immunofluorescent staining.

RESULTS

Peripheral CL-enhanced regeneration was equivalent between crush and transection CLs and was sustained for 28 days in both Ccr2 KO and WT mice despite MDM depletion. Similarly, the central CL response measured in dorsal roots was unchanged in Ccr2 KO mice. Macrophages at both the TL and CL, but not between them, stained for the pro-regenerative marker, arginase 1. TL macrophages were primarily CCR2-dependent MDMs and nearly absent in Ccr2 KO and Ccr2gfp/gfp KO mice. However, there were only slightly fewer Arg1+ macrophages in CCR2 null CLs than controls due to resident macrophage compensation. Zymosan injection into an intact WT sciatic nerve recruited Arg1+ macrophages but did not enhance regeneration. Finally, clodronate injection into Ccr2gfp KO CLs dramatically reduced CL macrophages. Combined with the Ccr2gfp KO background, depleting MDMs and TL macrophages, and a transection CL, physically removing the distal nerve environment, nearly all macrophages in the nerve were removed, yet CL-enhanced regeneration was not impaired.

CONCLUSIONS

Macrophages in the sciatic nerve are neither necessary nor sufficient to produce a CL response.

Lactate and lactylation in macrophage metabolic reprogramming: current progress and outstanding issues

It is commonly known that different macrophage phenotypes play specific roles in different pathophysiological processes. In recent years, many studies have linked the phenotypes of macrophages to their characteristics in different metabolic pathways, suggesting that macrophages can perform different functions through metabolic reprogramming. It is now gradually recognized that lactate, previously overlooked as a byproduct of glycolytic metabolism, acts as a signaling molecule in regulating multiple biological processes, including immunological responses and metabolism. Recently, lactate has been found to mediate epigenetic changes in macrophages through a newfound lactylation modification, thereby regulating their phenotypic transformation. This novel finding highlights the significant role of lactate metabolism in macrophage function. In this review, we summarize the features of relevant metabolic reprogramming in macrophages and the role of lactate metabolism therein. We also review the progress of research on the regulation of macrophage metabolic reprogramming by lactylation through epigenetic mechanisms.

Innovative Treatments to Counteract Endothelial Dysfunction in Chronic Kidney Disease Patients

In chronic kidney disease (CKD) patients, several risk factors contribute to the development of endothelial dysfunction (ED), which can be described as an alteration in the cell structure or in the function of the endothelium. Among the well-known CKD-related risk factors capable of altering the production of endothelium-derived relaxing factors, we include asymmetric dimethylarginine increase, reduced dimethylarginine dimethylamine hydrolase enzyme activity, low-grade chronic systemic inflammation, hyperhomocysteinemia, oxidative stress, insulin resistance, alteration of calcium phosphorus metabolism, and early aging. In this review, we also examined the most important techniques useful for studying ED in humans, which are divided into indirect and direct methods. The direct study of coronary endothelial function is considered the gold standard technique to evaluate if ED is present. In addition to the discussion of the main pharmacological treatments useful to counteract ED in CKD patients (namely sodium-glucose cotransporter 2 inhibitors and mineralocorticoid receptor antagonist), we elucidate innovative non-pharmacological treatments that are successful in accompanying the pharmacological ones. Among them, the most important are the consumption of extra virgin olive oil with high intake of minor polar compounds, adherence to a plant-dominant, low-protein diet (LPD), an adaptive physical activity program and, finally, ketoanalogue administration in combination with the LPD or the very low-protein diet.

Modulating the phenotype and function of bone marrow-derived macrophages via mandible and femur osteoblasts

Various studies have been investigated the phenotypic and functional distinctions of craniofacial and long bone cells involved in bone regeneration. However, the process of bone tissue regeneration after bone grafting involves complicated interactions between different cell types at the donor-recipient site. Additionally, differences in alterations of the immune microenvironment at the recipient site remained to be explored. Osteoblasts (OBs) and macrophages (MØ) play essential roles in the bone restoration and regeneration processes in the bone and immune systems, respectively. The modulation of MØ on OBs has been extensively explored in the literature, whereas limited research has been conducted on the influence of OBs on the MØ phenotype and function. In the present study, OBs from the mandible and femur (MOBs and FOBs, respectively) promoted cranial defect regeneration in rats, with better outcomes noted in the MOBs-treated group. After MOBs transplantation, a significant inflammatory response was induced, accompanied by an early increase in IL-10 secretion. And then, there was an upregulation in M2-MØ-related cell markers and inflammatory factor expression. Condition media (CM) of OBs mildly inhibited apoptosis in MØ, enhanced their migration and phagocytic functions, and concurrently increased iNOS and Arg1 expression, with MOB-CM demonstrating more pronounced effects compared to FOB-CM. In conclusion, our investigation showed that MOBs and FOBs have the ability to modulate MØ phenotype and function, with MOBs exhibiting a stronger regulatory potential. These findings provide a new direction for improving therapeutic strategies for bone regeneration in autologous bone grafts from the perspective of the immune microenvironment.

Modulation of the tumor microenvironment and mechanism of immunotherapy-based drug resistance in breast cancer

Breast cancer, the most frequent female malignancy, is often curable when detected at an early stage. The treatment of metastatic breast cancer is more challenging and may be unresponsive to conventional therapy. Immunotherapy is crucial for treating metastatic breast cancer, but its resistance is a major limitation. The tumor microenvironment (TME) is vital in modulating the immunotherapy response. Various tumor microenvironmental components, such as cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs), are involved in TME modulation to cause immunotherapy resistance. This review highlights the role of stromal cells in modulating the breast tumor microenvironment, including the involvement of CAF-TAM interaction, alteration of tumor metabolism leading to immunotherapy failure, and other latest strategies, including high throughput genomic screening, single-cell and spatial omics techniques for identifying tumor immune genes regulating immunotherapy response. This review emphasizes the therapeutic approach to overcome breast cancer immune resistance through CAF reprogramming, modulation of TAM polarization, tumor metabolism, and genomic alterations.

The role of tumor-associated macrophages in tumor immune evasion

BACKGROUND

Tumor growth is closely linked to the activities of various cells in the tumor microenvironment (TME), particularly immune cells. During tumor progression, circulating monocytes and macrophages are recruited, altering the TME and accelerating growth. These macrophages adjust their functions in response to signals from tumor and stromal cells. Tumor-associated macrophages (TAMs), similar to M2 macrophages, are key regulators in the TME.

METHODS

We review the origins, characteristics, and functions of TAMs within the TME. This analysis includes the mechanisms through which TAMs facilitate immune evasion and promote tumor metastasis. Additionally, we explore potential therapeutic strategies that target TAMs.

RESULTS

TAMs are instrumental in mediating tumor immune evasion and malignant behaviors. They release cytokines that inhibit effector immune cells and attract additional immunosuppressive cells to the TME. TAMs primarily target effector T cells, inducing exhaustion directly, influencing activity indirectly through cellular interactions, or suppressing through immune checkpoints. Additionally, TAMs are directly involved in tumor proliferation, angiogenesis, invasion, and metastasis. Developing innovative tumor-targeted therapies and immunotherapeutic strategies is currently a promising focus in oncology. Given the pivotal role of TAMs in immune evasion, several therapeutic approaches have been devised to target them. These include leveraging epigenetics, metabolic reprogramming, and cellular engineering to repolarize TAMs, inhibiting their recruitment and activity, and using TAMs as drug delivery vehicles. Although some of these strategies remain distant from clinical application, we believe that future therapies targeting TAMs will offer significant benefits to cancer patients.

Exploration of green preparation strategy for Lycium barbarum polysaccharide targeting Bacteroides proliferative and immune-enhancing activities and its potential use in geriatric foods

Lycium barbarum polysaccharide (LBP) is beneficial for elderly people, but its use is limited in geriatric foods due to the lack of comprehensive information on its preparation strategy and physical property. In this study, the low-ester rhamnogalacturonan-I (RG-I) type pectic polysaccharide-protein complexes with varying physicochemical properties, structural characteristics, proliferative activities on Bacteroides, and immune-enhancing activities on RAW 264.7 cells, were obtained by moderate-temperature acid extraction within adjustment of enzymatic and physical pretreatments. LBP prepared by moderate-temperature acid extraction, namely S1-A, showed the strongest immune-enhancing activity via increasing the phagocytosis capacity and NO release of RAW 264.7 cells by 23 % and 76 %, respectively. S1-A exhibited relatively high viscosity and calcium ion response characteristic with the application potential for thickened liquid foods for the elderly with dysphagia. LBP prepared by composite cellulase and pectinase pretreatment combined with moderate-temperature acid extraction, namely S1-M1, showed the strongest Bacteroides proliferative activity that was equivalent to 0.60-0.97 times of that of inulin. S1-M1 exhibited extremely low viscosity and strong tolerance to food nutrients with high processing applicability for fluid foods. This study provided crucial data for the preparation and application of LBP targeting gut microbiota disorders and immunosenescence for the development of geriatric foods.

Quercitrin improves cardiac remodeling following myocardial infarction by regulating macrophage polarization and metabolic reprogramming

The death and disability caused by myocardial infarction is a health problem that needs to be addressed worldwide, and poor cardiac repair and fibrosis after myocardial infarction seriously affect patient recovery. Postmyocardial infarction repair by M2 macrophages is of great significance for ventricular remodeling. Quercitrin (Que) is a common flavonoid in fruits and vegetables that has antioxidant, anti-inflammatory, antitumor and other effects, but whether it has a role in the treatment of myocardial infarction is unclear. In this study, we constructed a mouse myocardial infarction model and administered Que. We found through cardiac ultrasound that Que administration improved cardiac ejection fraction and reduced ventricular remodeling. Staining of heart sections and detection of fibrosis marker protein levels revealed that Que administration slowed fibrosis after myocardial infarction. Flow cytometry showed that the proportion of M2 macrophages in the mouse heart was increased and that the expression levels of M2 macrophage markers were increased in the Que-treated group. Finally, we identified by metabolomics that Que reduces glycolysis, increases aerobic phosphorylation, and alters arginine metabolic pathways, polarizing macrophages toward the M2 phenotype. Our research lays the foundation for the future application of Que in myocardial infarction and other cardiovascular diseases.