Spermidine endows macrophages anti-inflammatory properties by inducing mitochondrial superoxide-dependent AMPK activation, Hif-1α upregulation and autophagy

Intestinal metabolites in colitis-associated carcinogenesis: Building a bridge between host and microbiome

ABSTRACT

Microbial-derived metabolites are important mediators of host-microbial interactions. In recent years, the role of intestinal microbial metabolites in colorectal cancer has attracted considerable attention. These metabolites, which can be derived from bacterial metabolism of dietary substrates, modification of host molecules such as bile acids, or directly from bacteria, strongly influence the progression of colitis-associated cancer (CAC) by regulating inflammation and immune response. Here, we review how microbiome metabolites short-chain fatty acids (SCFAs), secondary bile acids, polyamines, microbial tryptophan metabolites, and polyphenols are involved in the tumorigenesis and development of CAC through inflammation and immunity. Given the heated debate on the metabolites of microbiota in maintaining gut homeostasis, serving as tumor molecular markers, and affecting the efficacy of immune checkpoint inhibitors in recent years, strategies for the prevention and treatment of CAC by targeting intestinal microbial metabolites are also discussed in this review.

Mitochondrial fission produces a Warburg effect via the oxidative inhibition of prolyl hydroxylase domain-2

Excessive mitochondrial fission and a shift to a Warburg phenotype are hallmarks of pulmonary hypertension (PH), although the mechanistic link between these processes remains unclear. We show that in pulmonary arterial endothelial cells (PAEC), Drp1 overexpression induces mitochondrial fission and increases glycolytic ATP production and glycolysis. This is due to mitochondrial reactive oxygen species (mito-ROS)-mediated activation of hypoxia-inducible factor-1α (HIF-1α) signaling, and this is linked to hydrogen peroxide (H2O2)-mediated inhibition of prolyl hydroxylase domain-2 (PHD2) due to its cysteine 326 oxidation and dimerization. Furthermore, these findings are validated in PAEC isolated from a lamb model of PH, which are glycolytic (Shunt PAEC), exhibit increases in both H2O2 and PHD2 dimer levels. The overexpression of catalase reversed the PHD2 dimerization, decreased HIF-1α levels, and attenuated glycolysis in Shunt PAEC. Our data suggest that reducing PHD2 dimerization could be a potential therapeutic target for PH.

Recent Advances in the Application of Hydrogels as Drug Carriers in Inflammatory Bowel Disease: A Review

Inflammatory bowel disease (IBD) is a chronic and refractory disease with increasing incidence, adversely impacting millions of patients worldwide. Current therapeutic strategies for IBD often exhibit considerable adverse effects, limited efficacy, and a high tendency for recurrence, highlighting the urgent need for novel therapeutic agents. Hydrogel, a three-dimensional hydrophilic network polymer material known for its excellent biocompatibility and responsiveness to stimuli, has been effectively utilized as a drug carrier across various therapeutic systems. The hydrogels' application in IBD treatment holds significant promise for enhancing therapeutic outcomes. This review synthesizes recent advancements in leveraging hydrogels as drug carriers for IBD management. The discussion encompasses the response mechanisms of hydrogels, their application in IBD therapy, and methods of administration. As drug delivery matrices, hydrogels exhibit considerable potential for treating IBD.

The Intestinal Macrophage-Intestinal Stem Cell Axis in Inflammatory Bowel Diseases: From Pathogenesis to Therapy

The gut plays a crucial role in digestion and immunity, so its balance is essential to overall health. This balance relies on dynamic interactions between intestinal epithelial cells, immune cells, and crypt stem cells. Inflammatory bowel disease (IBD), which consists of ulcerative colitis and Crohn's disease, is a chronic relapsing inflammatory disease of the gastrointestinal tract closely related to immune dysfunction. Stem cells, known for their ability to self-renew and differentiate, play an important role in repairing damaged intestinal epithelium and maintaining homeostasis in vivo. Macrophages are key gatekeepers of intestinal immune homeostasis and have a significant impact on IBD. Current research has focused on the link between epithelial cells and stem cells, but interactions with macrophages, which have been recognized as attractive targets for the development of new therapeutic approaches to disease, have been less explored. Recently, the developing field of immunometabolism has reinforced that metabolic reprogramming is a key determinant of macrophage function and subsequent disease progression. The aim of this review is to explore the role of the macrophage-stem cell axis in the maintenance of intestinal homeostasis and to summarize potential approaches to treating IBD by manipulating the cellular metabolism of macrophages, as well as the main opportunities and challenges faced. In summary, our overview provides a framework for understanding the critical role of macrophage immunometabolism in maintaining gut health and potential therapeutic targets.

Spermidine as a Potential Protective Agents Against Poly(I:C)-Induced Immune Response, Oxidative Stress, Apoptosis, and Testosterone Decrease in Yak Leydig Cells

Viral infections of the reproductive tract and testis in male yaks, often resulting from natural mating under grazing conditions, can lead to infertility due to Leydig cell (LC) apoptosis, immune activation, oxidative stress, and reduced testosterone production. Spermidine (SPD), a potential therapeutic agent with antioxidant and anti-aging properties, might alleviate oxidant stress, immune response, and virus infection caused by apoptosis. In this study, firstly testicular Leydig cells of yak were induced with Poly(I:C), the pathogen-associated molecular pattern of the dsRNA virus, as a pathogenic model at the cellular level. Secondly, immune response, apoptosis, oxidative stress, and testosterone synthesis were measured in LC with or without SPD culture medium. Finally, transcriptomic sequencing was utilized to investigate the molecular mechanisms underlying the protective effects of SPD. These results suggested Poly(I:C) damaged the function of Leydig cells, significantly decreased the concentration of testosterone, and induced immune response, oxidative stress, and cell apoptosis, while SPD significantly alleviated the immune response and oxidative stress, and then significantly inhibited cell apoptosis and restores testosterone production in LCs. Transcriptomic analysis revealed that SPD significantly alleviates inflammation and apoptosis induced by Poly(I:C), reducing immune response and cellular damage through the regulation of several key gene expressions. These findings suggest SPD has the potential ability to mitigate Poly(I:C)-induced immune response, oxidative stress, and apoptosis, and then restore testosterone production in Leydig cells, offering a promising strategy to protect and enhance male yak fertility after infection with dsRNA virus.

AMPK in Chemoradiotherapy-Induced Oral Mucositis

BACKGROUND

Oral mucositis (OM) is a prevalent adverse effect of radiotherapy and chemotherapy, significantly impacting cancer patients' well-being and potentially increasing mortality rates. Understanding OM's pathogenesis and identifying effective preventative and therapeutic agents are clinically crucial.

METHODS

This study analyzed RNA-Seq data from the GEO database, focusing on OM samples post-radiotherapy and chemotherapy. Differential gene expression analysis between OM and non-OM groups, followed by gene ontology (GO) enrichment analysis of differentially expressed genes (DEGs), was conducted. LASSO regression identified five potential biomarkers, and CIBERSORT assessed immune infiltration in OM samples. Correlations between biomarkers and immune infiltration were explored, and the connectivity map (CMAP) screened potential therapeutic drugs. The top 10 drugs were validated through molecular docking.

RESULTS

A total of 47 DEGs were identified, primarily involved in mitotic sister chromatid separation according to GO enrichment analysis. CIBERSORT analysis revealed significant changes in B cell naive and dendriform cells (DCs) resting content in the OM group. PRKAA2, encoding the AMP-activated protein kinase (AMPK) catalytic subunit, showed a negative correlation with DC resting content. Molecular docking from CMAP identified aloisine and teniposide as potential agents for OM induced by radiotherapy and chemotherapy.

CONCLUSION

AMPK emerges as a crucial regulator in OM post radiotherapy and chemotherapy, implicating sister chromatid separation, where DCs may play a pivotal role. Aloisine and Teniposide appear promising for OM prevention or treatment associated with these treatments.

Closed-loop theranostic microgels for immune microenvironment modulation and microbiota remodeling in ulcerative colitis

Inflammatory bowel disease (IBD) is characterized by the upregulation of reactive oxygen species (ROS) and dysfunction of gut immune system, and microbiota. The conventional treatments mainly focus on symptom control with medication by overuse of drugs. There is an urgent need to develop a closed-loop strategy that combines in situ monitoring and precise treatment. Herein, we innovatively designed the 'cluster munition structure' theranostic microgels to realize the monitoring and therapy for ulcerative colitis (a subtype of IBD). The superoxide anion specific probe (tetraphenylethylene-coelenterazine, TPC) and ROS-responsive nanogels consisting of postbiotics urolithin A (UA) were loaded into alginate and ion-crosslinked to obtain the theranostic microgels. The theranostic microgels could be delivered to the inflammatory site, where the environment-triggered breakup of the microgels and release of the nanogels were achieved in sequence. The TPC-UA group had optimal results in reducing inflammation, repairing colonic epithelial tissue, and remodeling microbiota, leading to inflammation amelioration and recovery of tight junction between the colonic epithelium, and maintenance of gut microbiota. During the recovery process, the local chemiluminescence intensity, which is proportional to the degree of inflammation, was gradually inhibited. The cluster munition of theranostic microgels displayed promising outcomes in monitoring inflammation and precise therapy, and demonstrated the potential for inflammatory disease management.

Polyamine metabolism and anti-tumor immunity

Growing attention has been directed toward the critical role of polyamines in the tumor microenvironment and immune regulation. Polyamines, primarily comprising putrescine, spermidine, and spermine, are tightly regulated through coordinated biosynthesis, catabolism, and transport, with distinct metabolic patterns between normal and cancerous tissues. Emerging evidence highlights the pivotal role of polyamine metabolism in tumor initiation, progression, and metastasis. This review aims to elucidate the differences in polyamine biosynthesis, transport, and catabolism between normal and cancerous tissues, as well as the associated alterations in tumor epigenetic modifications and resistance to immune checkpoint blockade driven by polyamine metabolism. Polyamine metabolism influences both tumor cells and the tumor microenvironment by modulating immune cell phenotypes-shifting them towards either tumor suppression or immune evasion within the tumor immune microenvironment. Additionally, polyamine metabolism impacts immunotherapy through its regulation of key enzymes. This review also explores potential therapeutic targets and summarizes the roles of polyamine inhibitors in combination with immunotherapy for cancer treatment, offering a novel perspective on therapeutic strategies.

Natural products targeting AMPK signaling pathway therapy, diabetes mellitus and its complications

Diabetes mellitus (DM) ranks among the most prevalent chronic metabolic diseases, characterized primarily by a persistent elevation in blood glucose levels. This condition typically stems from either insufficient insulin secretion or a functional defect in the insulin itself. Clinically, diabetes is primarily classified into type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), with T2DM comprising nearly 90% of all diagnosed cases. Notably, the global incidence of T2DM has surged dramatically over recent decades. The adenylate-activated protein kinase (AMPK) signaling pathway is crucial in regulating cellular energy metabolism, marking it as a significant therapeutic target for diabetes and related complications. Natural products, characterized by their diverse origins, multifaceted bioactivities, and relative safety, hold considerable promise in modulating the AMPK pathway. This review article explores the advances in research on natural products that target the AMPK signaling pathway, aiming to inform the development of innovative antidiabetic therapies.

Autophagic flux-lipid droplet biogenesis cascade sustains mitochondrial fitness in colorectal cancer cells adapted to acidosis

Cancer development is associated with adaptation to various stressful conditions, such as extracellular acidosis. The adverse tumor microenvironment also selects for increased malignancy. Mitochondria are integral in stress sensing to allow for tumor cells to adapt to stressful conditions. Here, we show that colorectal cancer cells adapted to acidic microenvironment (CRC-AA) are more reliant on oxidative phosphorylation than their parental cells, and the acetyl-CoA in CRC-AA cells are generated from fatty acids and glutamine, but not from glucose. Consistently, CRC-AA cells exhibit increased mitochondrial mass and fitness that depends on an upregulated autophagic flux-lipid droplet axis. Lipid droplets (LDs) function as a buffering system to store the fatty acids derived from autophagy and to protect mitochondria from lipotoxicity in CRC-AA cells. Blockade of LD biogenesis causes mitochondrial dysfunction that can be rescued by inhibiting carnitine palmitoyltransferase 1 α (CPT1α). High level of mitochondrial superoxide is essential for the AMPK activation, resistance to apoptosis, high autophagic flux and mitochondrial function in CRC-AA cells. Thus, our results demonstrate that the cascade of autophagic flux and LD formation plays an essential role in sustaining mitochondrial fitness to promote cancer cell survival under chronic acidosis. Our findings provide insight into the pro-survival metabolic plasticity in cancer cells under microenvironmental or therapeutic stress and imply that this pro-survival cascade may potentially be targeted in cancer therapy.

Role of polyamines in intestinal mucosal barrier function

The intestinal epithelium is a rapidly self-renewing tissue; the rapid turnover prevents the invasion of pathogens and harmful components from the intestinal lumen, preventing inflammation and infectious diseases. Intestinal epithelial barrier function depends on the epithelial cell proliferation and junctions, as well as the state of the immune system in the lamina propria. Polyamines, particularly putrescine, spermidine, and spermine, are essential for many cell functions and play a crucial role in mammalian cellular homeostasis, such as that of cell growth, proliferation, differentiation, and maintenance, through multiple biological processes, including translation, transcription, and autophagy. Although the vital role of polyamines in normal intestinal epithelial cell growth and barrier function has been known since the 1980s, recent studies have provided new insights into this topic at the molecular level, such as eukaryotic initiation factor-5A hypusination and autophagy, with rapid advances in polyamine biology in normal cells using biological technologies. This review summarizes recent advances in our understanding of the role of polyamines in regulating normal, non-cancerous, intestinal epithelial barrier function, with a particular focus on intestinal epithelial renewal, cell junctions, and immune cell differentiation in the lamina propria.

Histone lactylation in macrophage biology and disease: from plasticity regulation to therapeutic implications

Epigenetic modifications have been identified as critical molecular determinants influencing macrophage plasticity and heterogeneity. Among these, histone lactylation is a recently discovered epigenetic modification. Research examining the effects of histone lactylation on macrophage activation and polarization has grown substantially in recent years. Evidence increasingly suggests that lactate-mediated changes in histone lactylation levels within macrophages can modulate gene transcription, thereby contributing to the pathogenesis of various diseases. This review provides a comprehensive analysis of the role of histone lactylation in macrophage activation, exploring its discovery, effects, and association with macrophage diversity and phenotypic variability. Moreover, it highlights the impact of alterations in macrophage histone lactylation in diverse pathological contexts, such as inflammation, tumorigenesis, neurological disorders, and other complex conditions, and demonstrates the therapeutic potential of drugs targeting these epigenetic modifications. This mechanistic understanding provides insights into the underlying disease mechanisms and opens new avenues for therapeutic intervention.

Gut microbiota as a modulator of type 1 diabetes: A molecular perspective

Type 1 diabetes (T1D) is defined as an autoimmune metabolic disorder, characterized by destruction of pancreatic β-cells and high blood sugar levels. If left untreated, T1D results in severe health complications, including cardiovascular and kidney disease, as well as nerve damage, with ultimately grave consequences. Besides the role of genetic and certain environmental factors in T1D development, in the last decade, one new player emerged to affect T1D pathology as well, and that is a gut microbiota. Dysbiosis of gut bacteria can contribute to T1D by gut barrier disruption and the activation of autoimmune response, leading to the destruction of insulin producing cells, causing the development and aggravation of T1D symptoms. The relationship between gut microbiota and diabetes is complex and varies between individuals and additional research is needed to fully understand the effects of gut microbiome alternations in T1D pathogenesis. Therefore, the goal of this review is to understand the current knowledge in underlying molecular mechanism of gut microbiota effects, which leads to the new approaches for further studies in the prevention and treatment of T1D.

Postbiotics as Antiinflammatory and Immune-Modulating Bioactive Compounds in Metabolic Dysfunction-Associated Steatotic Liver Disease

Postbiotics, defined as products or metabolic byproducts secreted by live bacteria or released after bacterial lysis, are emerging as promising therapeutic agents for metabolic dysfunction-associated steatotic liver disease (MASLD). This review explores the antiinflammatory and immunomodulatory properties of various postbiotics, including exopolysaccharides, lipoteichoic acid, short-chain fatty acids, hydrogen sulfide, polyamines, tryptophan derivatives, and polyphenol metabolites. These compounds have demonstrated potential in mitigating steatotic liver infiltration, reducing inflammation, and slowing fibrosis progression in preclinical studies. Notably, postbiotics exert their beneficial effects by modulating gut microbiota composition, enhancing intestinal barrier function, optimizing lipid metabolism, reducing hepatic inflammation and steatosis, and exhibiting hepatoprotective properties. However, translating these findings into clinical practice requires well-designed trials to validate efficacy and safety, standardize production and characterization, and explore personalized approaches and synergistic effects with other therapeutic modalities. Despite challenges, the unique biological properties of postbiotics, such as enhanced safety compared to probiotics, make them attractive candidates for developing novel nutritional interventions targeting the multifactorial pathogenesis of MASLD. Further research is needed to establish their clinical utility and potential to improve liver and systemic outcomes in this increasingly prevalent condition.

Tumor cell-derived spermidine promotes a protumorigenic immune microenvironment in glioblastoma via CD8+ T cell inhibition

The glioblastoma (GBM) microenvironment is enriched in immunosuppressive factors that potently interfere with the function of cytotoxic T lymphocytes. Cancer cells can directly affect the immune system, but the mechanisms driving these interactions are not completely clear. Here, we demonstrate that the polyamine metabolite spermidine (SPD) was elevated in the GBM tumor microenvironment. Exogenous administration of SPD drove tumor aggressiveness in an immune-dependent manner in preclinical mouse models via reduction of CD8+ T cell frequency and reduced cytotoxic function. Knockdown of ornithine decarboxylase, the rate-limiting enzyme in SPD synthesis, did not affect cancer cell growth in vitro but did result in extended survival. Furthermore, patients with GBM with a more favorable outcome had a significant reduction in SPD compared with patients with a poor prognosis. Our results demonstrate that SPD functions as a cancer cell-derived metabolite that drives tumor progression by reducing CD8+ T cell numbers and function.

Loss of O6-methylguanine DNA methyltransferase (MGMT) in macrophages alters responses to TLR3 stimulation and enhances DNA double-strand breaks and mitophagy

O6-methylguanine-DNA methyltransferase (MGMT) is a DNA damage repair enzyme. The roles of this enzyme in immune cells remain unclear. In this study, we explored the roles of MGMT in bone marrow-derived murine macrophages (BMMs) via the use of MGMT knockout (KO) mice. Loss of MGMT altered the response to TLR3 agonists (poly (I:C)), such as dampening the production of TNFα and IL-6. Increased DNA double-strand breaks (DSBs) were observed in MGMT-KO macrophages but did not result in increased cell death. MGMT localized to both nuclei and mitochondria at increasing levels during poly (I:C) stimulation. MGMT deficiency increased the production of mitochondrial reactive oxygen species (mtROS), which was correlated with increased mitophagy. The underlying mechanism involves mediation through activation of the AMPKα pathway. Taken together, our findings reveal the roles of MGMT in macrophages in regulating the response to TLR3, which links DSBs to mtROS and mitophagy via the AMPKα pathway. These roles may have consequences for the inflammatory response and chronic inflammation.

Spermidine Associated with Gut Microbiota Protects Against MRSA Bloodstream Infection by Promoting Macrophage M2 Polarization

Methicillin-resistant Staphylococcus aureus (MRSA) is a major human pathogen that causes various diseases. Extensive researches highlight the significant role of gut microbiota and its metabolites, particularly spermidine, in infectious diseases. However, the immunomodulatory mechanisms of spermidine in MRSA-induced bloodstream infection remain unclear. Here, we confirmed the protective effects of spermidine in bloodstream infection in mice. Spermidine reduced the bacterial load and expression of inflammatory factors by shifting the macrophage phenotype to an anti-inflammatory phenotype, ultimately prolonging the survival of the infected mice. The protective effect against MRSA infection may rely on the elevated expression of protein tyrosine phosphatase nonreceptor 2 (PTPN2). Collectively, these findings confirm the immunoprotective effects of spermidine via binding to PTPN2 in MRSA bloodstream infection, providing new ideas for the treatment of related infectious diseases.

Soymilk yogurt fermented using Pediococcus pentosaceus TOKAI 759 m improves mice gut microbiota and reduces pro-inflammatory cytokine production

This study aimed to determine the anti-inflammatory activities and bioactive compounds of soymilk yogurt prepared using Lactiplantibacillus plantarum TOKAI 17 or Pediococcus pentosaceus TOKAI 759 m. Mice were divided into five groups: normal diet (ND), soymilk, soymilk yogurt using L. plantarum TOKAI 17 (SY 17) or P. pentosaceus TOKAI 759 m (SY 759 m), and 0.5 × 109 cells of each starter strain (BC 17 or BC759m). In the SY 759 m group, the serum pro-inflammatory cytokine levels and the cytotoxicity of natural killer cells were attenuated compared to the ND group. In the cecum microbiota, the abundances of butyrate-producing bacteria increased in the SY 759 m and BC 17 groups. Furthermore, SY 759 m metabolites contained high levels of aglycone isoflavone, adenine and showed a significant decrease in CCL-2 and interleukin-6 production in lipopolysaccharide-induced macrophage. In conclusion, soymilk yogurt produced using P. pentosaceus TOKAI 759 m modulates the gut microbiota and can potentially prevent pro-inflammatory cytokine production.

Metformin impacts the differentiation of mouse bone marrow cells into macrophages affecting tumour immunity

Background

Epidemiological studies suggest that metformin reduces the risk of developing several types of cancer, including gliomas, and improves the overall survival in cancer patients. Nevertheless, while the effect of metformin on cancer cells has been extensively studied, its impact on other components of the tumour microenvironment, such as macrophages, is less understood.

Results

Metformin-treated mouse bone marrow cells differentiate into spindle-shaped macrophages exhibiting increased phagocytic activity and tumour cell cytotoxicity coupled with modulated expression of co-stimulatory molecules displaying reduced sensitivity to inflammatory cues compared with untreated cells. Transcriptional analyses of metformin-treated mouse bone marrow-derived macrophages show decreased expression levels of pro-tumour genes, including Tgfbi and Il1β, related to enhanced mTOR/HIF1α signalling and metabolic rewiring towards glycolysis.

Significance

Our study provides novel insights into the immunomodulatory properties of metformin in macrophages and its potential application in preventing tumour onset and in cancer immunotherapy.

Effect of Spermidine on Endothelial Function in Systemic Lupus Erythematosus Mice

Endothelial dysfunction is common in Systemic Lupus Erythematosus (SLE), even in the absence of cardiovascular disease. Evidence suggests that impaired mitophagy contributes to SLE. Mitochondrial dysfunction is also associated with impaired endothelial function. Spermidine, a natural polyamine, stimulates mitophagy by the PINK1-parkin pathway and counters age-associated endothelial dysfunction. However, the effect of spermidine on mitophagy and vascular function in SLE has not been explored. To address this gap, 9-week-old female lupus-prone (MRL/lpr) and healthy control (MRL/MpJ) mice were randomly assigned to spermidine treatment (lpr_Spermidine and MpJ_Spermidine) for 8 weeks or as control (lpr_Control and MpJ_Control). lpr_Control mice exhibited impaired endothelial function (e.g., decreased relaxation to acetylcholine), increased markers of inflammation, and lower protein content of parkin, a mitophagy marker, in the thoracic aorta. Spermidine treatment prevented endothelial dysfunction in MRL-lpr mice. Furthermore, aortas from lpr_Spermidine mice had lower levels of inflammatory markers and higher levels of parkin. Lupus phenotypes were not affected by spermidine. Collectively, these results demonstrate the beneficial effects of spermidine treatment on endothelial function, inflammation, and mitophagy in SLE mice. These results support future studies of the beneficial effects of spermidine on endothelial dysfunction and cardiovascular disease risk in SLE.

Screening of genes related to programmed cell death in esophageal squamous cell carcinoma and construction of prognostic model based on transcriptome analysis

OBJECTIVES

To screen programmed cell death (PCD)-related genes in esophageal squamous cell carcinoma (ESCC) based on transcriptomic data and to explore its clinical value.

METHODS

Differentially expressed PCD genes (DEPCDGs) were screened from ESCC transcriptome and clinical data in TCGA database. Univariate COX and LASSO COX were performed on prognostically DEPCDGs in ESCC to develop prognostic model. Differences in immune cell infiltration in different RiskScore groups were determined by ssGSEA and CIBERSORT. The role of RiskScore in immunotherapy response was explored using Tumor Immune Dysfunction and Exclusion (TIDE) and IMvigor210 cohorts.

RESULTS

Fourteen DEPCDGs associated with prognosis were tapped in ESCC. These DEPCDGs form a RiskScore with good predictive performance for prognosis. RiskScore demonstrated excellent prediction accuracy in three data sets. The abundance of M2 macrophages and Tregs was higher in the high RiskScore group, and the abundance of M1 macrophages was higher in the low RiskScore group. The RiskScore also showed good immunotherapy sensitivity. RT-qPCR analysis showed that AUP1, BCAP31, DYRK2, TAF9 and UBQLN2 were higher expression in KYSE-150 cells. Knockdown BCAP31 inhibited migration and invasion.

CONCLUSION

A prognostic risk model can predict prognosis of ESCC and may be a useful biomarker for risk stratification and immunotherapy assessment.

CONSORT article: Single-cell sequencing analysis revealed CMKLR1+ macrophage as a subpopulation of macrophage with tumor-suppressive characteristics in oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is an aggressive oral malignancy. Metastasis and postoperative recurrence are major causes of a high mortality of OSCC. The landscape of immune cells in OSCC remained to be comprehensively explored.

METHODS

Tumor tissues of OSCC patients were collected from the Gene Expression Omnibus database, based on which single-cell sequencing analysis was performed to identify subtypes of macrophages and to annotate the subpopulations according to the expression levels of cell marker genes. Functional enrichment analysis was performed to explore the biological processes involved in each cell subcluster. Gene regulatory networks driven by SPECIFIC transcription factors (TFs) were developed applying single-cell regulatory network inference and clustering (SCENIC) analysis. Binding strength between receptors and ligands between different cells was analyzed using cell communication analysis.

RESULTS

A single-cell landscape in OSCC was successfully developed and a total of 11 cell clusters were identified. Specifically, CD163 + macrophages were a crucial type of macrophage with 4 cell subpopulations, namely, SAT1 + macrophages, IDO1 + macrophages, TRIM29 + macrophages, and CMKLR1 + macrophages. IDO1 + macrophages and CMKLR1 + macrophages mainly had the characteristics of M1-type macrophages. CMKLR1 + macrophages fulfilled the function of M1-type macrophages to inhibit OSCC progression. IDO1 + macrophages and CMKLR1 + macrophages were both involved in the activation response of T cells. CMLKR1 + macrophages had a stronger activating effect on T cells. CMKLR1 + macrophages directly regulated the proliferation of epithelial cells and inhibited the progression of OSCC.

CONCLUSION

CMKLR1 + macrophages in OSCC were identified as a crucial cell subpopulation of macrophages in inhibiting tumor progression. Adjusting the infiltration abundance and cell activity of CMKLR1 + macrophages may be a novel therapeutic direction to improve OSCC prognosis.

Ovarian aging: energy metabolism of oocytes

In women who are getting older, the quantity and quality of their follicles or oocytes and decline. This is characterized by decreased ovarian reserve function (DOR), fewer remaining oocytes, and lower quality oocytes. As more women choose to delay childbirth, the decline in fertility associated with age has become a significant concern for modern women. The decline in oocyte quality is a key indicator of ovarian aging. Many studies suggest that age-related changes in oocyte energy metabolism may impact oocyte quality. Changes in oocyte energy metabolism affect adenosine 5'-triphosphate (ATP) production, but how related products and proteins influence oocyte quality remains largely unknown. This review focuses on oocyte metabolism in age-related ovarian aging and its potential impact on oocyte quality, as well as therapeutic strategies that may partially influence oocyte metabolism. This research aims to enhance our understanding of age-related changes in oocyte energy metabolism, and the identification of biomarkers and treatment methods.

Recommendations for nutritional supplements for dry eye disease: current advances

Dry eye disease (DED) represents a prevalent ocular surface disease. The development of effective nutritional management strategies for DED is crucial due to its association with various factors such as inflammation, oxidative stress, deficiencies in polyunsaturated fatty acids (PUFAs), imbalanced PUFA ratios, and vitamin insufficiencies. Extensive research has explored the impact of oral nutritional supplements, varying in composition and dosage, on the symptoms of DED. The main components of these supplements include fish oils (Omega-3 fatty acids), vitamins, trace elements, and phytochemical extracts. Beyond these well-known nutrients, it is necessary to explore whether novel nutrients might contribute to more effective DED management. This review provides a comprehensive update on the therapeutic potential of nutrients and presents new perspectives for combination supplements in DED treatment.

Nitazoxanide protects against experimental ulcerative colitis through improving intestinal barrier and inhibiting inflammation

Ulcerative colitis is a chronic disease with colonic mucosa injury. Nitazoxanide is an antiprotozoal drug in clinic. Nitazoxanide and its metabolite tizoxanide have been demonstrated to activate AMPK and inhibit inflammation, therefore, the aim of the present study is to investigate the effect of nitazoxanide on dextran sulfate sodium (DSS)-induced colitis and the underlying mechanism. Oral administration of nitazoxanide ameliorated the symptoms of mice with DSS-induced colitis, as evidenced by improving the increased disease activity index (DAI), the decreased body weight, and the shortened colon length. Oral administration of nitazoxanide ameliorated DSS-induced intestinal barrier dysfunction and reduced IL-6 and IL-17 expression in colon tissues. Mechanistically, nitazoxanide and its metabolite tizoxanide treatment activated AMPK and inhibited JAK2/STAT3 signals. Nitazoxanide and tizoxanide treatment increased caudal type homeobox 2 (CDX2) expression, increased alkaline phosphatase (ALP) activity and promoted tight junctions in Caco-2 cells. Nitazoxanide and tizoxanide treatment restored the decreased zonula occludens-1(ZO-1) and occludin protein levels induced by LPS or IL-6 in Caco-2 cells. On the other hand, nitazoxanide and tizoxanide regulated macrophage bias toward M2 polarization, as evidenced by the increased arginase-1expression in bone marrow-derived macrophages (BMDM). Nitazoxanide and tizoxanide reduced the increased IL-6, iNOS and CCL2 pro-inflammatory gene expressions and inhibited JAK2/STAT3 activation in BMDM induced by LPS. In conclusion, nitazoxanide protects against DSS-induced ulcerative colitis in mice through improving intestinal barrier and inhibiting inflammation and the underlying mechanism involves AMPK activation and JAK2/STAT3 inhibition.

Polyamines: the pivotal amines in influencing the tumor microenvironment

Cellular proliferation, function and survival is reliant upon maintaining appropriate intracellular polyamine levels. Due to increased metabolic needs, cancer cells elevate their polyamine pools through coordinated metabolism and uptake. High levels of polyamines have been linked to more immunosuppressive tumor microenvironments (TME) as polyamines support the growth and function of many immunosuppressive cell types such as MDSCs, macrophages and regulatory T-cells. As cancer cells and other pro-tumorigenic cell types are highly dependent on polyamines for survival, pharmacological modulation of polyamine metabolism is a promising cancer therapeutic strategy. This review covers the roles of polyamines in various cell types of the TME including both immune and stromal cells, as well as how competition for nutrients, namely polyamine precursors, influences the cellular landscape of the TME. It also details the use of polyamines as biomarkers and the ways in which polyamine depletion can increase the immunogenicity of the TME and reprogram tumors to become more responsive to immunotherapy.

Possible Role of Cellular Polyamine Metabolism in Neuronal Apoptosis

Recent studies have shown that cellular levels of polyamines (PAs) are significantly altered in neurodegenerative diseases. Evidence from in vivo animal and in vitro cell experiments suggests that the cellular levels of various PAs may play important roles in the central nervous system through the regulation of oxidative stress, mitochondrial metabolism, cellular immunity, and ion channel functions. Dysfunction of PA metabolism related enzymes also contributes to neuronal injury and cognitive impairment in many neurodegenerative diseases. Therefore, in the current work, evidence was collected to determine the possible associations between cellular levels of PAs, and related enzymes and the development of several neurodegenerative diseases, which could provide a new idea for the treatment of neurodegenerative diseases in the future.

Crosstalk between hypoxia-inducible factor-1α and short-chain fatty acids in inflammatory bowel disease: key clues toward unraveling the mystery

The human intestinal tract constitutes a complex ecosystem, made up of countless gut microbiota, metabolites, and immune cells, with hypoxia being a fundamental environmental characteristic of this ecology. Under normal physiological conditions, a delicate balance exists among these complex "residents", with disruptions potentially leading to inflammatory bowel disease (IBD). The core pathology of IBD features a disrupted intestinal epithelial barrier, alongside evident immune and microecological disturbances. Central to these interconnected networks is hypoxia-inducible factor-1α (HIF-1α), which is a key regulator in gut cells for adapting to hypoxic conditions and maintaining gut homeostasis. Short-chain fatty acids (SCFAs), as pivotal gut metabolites, serve as vital mediators between the host and microbiota, and significantly influence intestinal ecosystem. Recent years have seen a surge in research on the roles and therapeutic potential of HIF-1α and SCFAs in IBD independently, yet reviews on HIF-1α-mediated SCFAs regulation of IBD under hypoxic conditions are scarce. This article summarizes evidence of the interplay and regulatory relationship between SCFAs and HIF-1α in IBD, pivotal for elucidating the disease's pathogenesis and offering promising therapeutic strategies.

Roxadustat ameliorates experimental colitis in mice by regulating macrophage polarization through increasing HIF level

BACKGROUND

Gastro-intestinal (GI) tract inflammation is as a result of inflammatory hypoxia which is also induced by long-standing group of disorders like inflammatory-bowel disease (IBD). Regulation of GI immune homeostasis by macrophage involves hypoxia-inducible factor (HIF). As inhibitor of HIF prolyl hydroxylase, roxadustat (ROX) increases the levels of HIF.

METHODS

We induced experimental colitis (EC) model in mice via dextran-sulfate sodium (DSS) to evaluate ROX role in above-mentioned disease.

RESULTS

ROX ameliorated EC in mice by blocking colonic length shorten and loss of body weight, thereby reducing scores of disease-activity index (DAI) and histopathology. ROX significantly reduced inflammatory cytokines levels, suppressed M1 and increased M2 macrophage polarization in colonic tissues. Besides, ROX blocked declining hematocrit (HCT) level in blood and increased HIF-1-α and HIF-2-α level in colonic tissues. The inhibitor of HIF-1- α, KC7F2 decreased body weight and colonic length in ROX-treated DSS mice. Meanwhile, DAI scores and histopathology in KC7F2 treated DSS mice were markedly higher than that of treatment with ROX alone. KC7F2 treatments also significantly increased inflammatory cytokines levels, respectively promoted and reduced polarization of M1 and M2 macrophages in colonic tissue from ROX treated mice. Further, KC7F2 treatments inhibited ROX induced HCT level increasing in blood and decreased HIF-1-α and HIF-2-α level in colonic tissue.

CONCLUSION

Collectively, we discovered that ROX ameliorated EC in mice by regulating macrophage polarization through promotion of HIF expression.

GENERAL SIGNIFICANCE

Taken together, we developed a new application of ROX, which provides new ideas and a scientific basis for IBD treatment.

Sesquiterpene from Artemisia argyi seed extracts: A new anti-acute peritonitis agent that suppresses the MAPK pathway and promotes autophagy

To find novel anti-inflammatory drugs, we screened anti-inflammatory compounds from 18 different types of Artemisia argyi seed extracts. The in vitro and in vivo anti-inflammatory activities of the screened compounds and their mechanisms were characterized. We first detected the cytotoxic effect of the compounds on RAW264.7 cells and the inhibitory effect on LPS-induced NO release. It was found that sesquiterpenoids CA-2 and CA-4 had low cytotoxic and strong NO inhibitory activity with an IC50 of 4.22 ± 0.61 μM and 2.98 ± 0.23 μM for NO inhibition, respectively. Therefore, compound CA-4 was studied in depth. We found that compound CA-4 inhibited LPS-induced pro-inflammatory factor production and M1 macrophage differentiation in RAW264.7 cells. Additionally, CA-4 inhibited the expression of p-ERK1/2, p-JNK, iNOS, and COX-2 by blocking the MAPK signaling pathway. CA-4 also promoted the expression of autophagy-related proteins such as LC3 II and Beclin-1 by inhibiting activation of the PI3K/AKT/mTOR signaling pathway, and promoted the generation of autophagosomes. Finally, CA-4 significantly inhibited the degree of inflammation in mice with acute peritonitis, showing good anti-inflammatory activity in vivo. Consequently, compound CA-4 may be a promising drug for the treatment of acute inflammatory diseases and provide new ideas for the synthesis of novel anti-inflammatory compounds.

Pathway analysis of spermidine anti-oxidative stress and inducing autophagy in granulosa cells of Sichuan white geese

Spermidine, a natural polyamine, has been proven antioxidant function, but its pathway and mechanism of action remain unclear. Based on the oxidative stress model by 3-nitropropionic acid (3-NPA), the study explored the pathways by spermidine to rescue oxidative stress via autophagic process in goose granulosa cells by RNA-seq and RNA interference. In transcriptional regulation, in addition to KEGG pathways related to cell proliferation and differentiation, lots of KEGG pathways associated with inflammation, metabolism, and signaling were also significantly enriched in 3-NPA vs. 3-NPA + spermidine treatments. Six key genes (JUN, CD44, KITLG, RND2, BMP4 and KALRN) involved in spermidine-mediated anti-oxidative stress were screened. Furthermore, the experimental results showed that spermidine (80 μmol/L) significantly increased autophagic gene expression in goose granulosa cells, while EP300-siRNA or MAP1S-siRNA also significantly increased autophagic process. The autophagic gene expressions were no difference between EP300-siRNA and EP300-siRNA + spermidine treatments, although spermidine significantly increased autophagic process of granulosa cells compared to MAP1S-siRNA alone. In addition, inhibition of mTOR pathway significantly increased autophagic gene expression, which was further enhanced by spermidine in combined with mTOR inhibitor. These results suggest that spermidine can alleviate oxidative stress by inducing autophagy regulated by EP300, MAP1S and mTOR as well as regulating other independent gene expressions in goose granulosa cells.

Polyamine Signal through HCC Microenvironment: A Key Regulator of Mitochondrial Preservation and Turnover in TAMs

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, and, with increasing research on the tumor immune microenvironment (TIME), the immunosuppressive micro-environment of HCC hampers further application of immunotherapy, even though immunotherapy can provide survival benefits to patients with advanced liver cancer. Current studies suggest that polyamine metabolism is not only a key metabolic pathway for the formation of immunosuppressive phenotypes in tumor-associated macrophages (TAMs), but it is also profoundly involved in mitochondrial quality control signaling and the energy metabolism regulation process, so it is particularly important to further investigate the role of polyamine metabolism in the tumor microenvironment (TME). In this review, by summarizing the current research progress of key enzymes and substrates of the polyamine metabolic pathway in regulating TAMs and T cells, we propose that polyamine biosynthesis can intervene in the process of mitochondrial energy metabolism by affecting mitochondrial autophagy, which, in turn, regulates macrophage polarization and T cell differentiation. Polyamine metabolism may be a key target for the interactive dialog between HCC cells and immune cells such as TAMs, so interfering with polyamine metabolism may become an important entry point to break intercellular communication, providing new research space for developing polyamine metabolism-based therapy for HCC.

IL-17A is involved in the hyperplasia of blood vessels in local lesions of psoriasis by inhibiting autophagy

OBJECTIVE

Increased angiogenesis is a pathological feature of psoriasis, but the pathomechanisms of angiogenesis in psoriasis are not clear. Interleukin-17A (IL-17A) is the major effect factor in the pathogenesis of psoriasis. Our results showed that IL-17A can promote angiogenesis and cause endothelial cell inflammation. Autophagy plays an important role not only in regulating inflammation, but also in regulating angiogenesis. Whether angiogenesis in psoriasis is related to autophagy remains unclear. In this study, we treated human umbilical vein endothelial cells (HUVECs) with IL-17A to simulate increased angiogenesis to study whether increased angiogenesis in psoriasis is related to autophagy.

METHODS AND RESULTS

Our results showed that treatment of HUVECs with IL-17A significantly increased angiogenesis and expression levels of mRNA for multiple proinflammatory cytokines (CCL20, IL-8, CCL2, IL-6, and IL-1β) and, while decreasing intracellular levels of nitric oxide (NO) and NO synthase (NOS) activity. Moreover, IL-17A inhibited autophagy as shown that IL-17A significantly increased expression levels of LC3II and p62 proteins. Induction of autophagy ameliorated IL-17A-mediated inflammatory response and inhibited angiogenesis, accompanied by increased p-AMPKα(Thr172) and p-ULK1(Ser555) expression, and decreased p-mTOR(Ser2448) and p-ULK1(Ser757) expression. Furthermore, inhibition of either AMPK or lysosomal acidification completely overrode autophagy-induced changes in angiogenesis and NOS activity. Finally, induction of autophagy decreased apoptosis and caspase-3 activity in IL-17A-treated HUVECs.

CONCLUSIONS

These results showed that IL-17A is involved in angiogenesis and inflammatory response by inhibiting autophagy through AMPK signaling pathway, suggesting that autophagy may be a new therapeutic target for psoriasis.

Pentagalloyl glucose induces anti-inflammatory macrophage polarization - suppressing macrophage mediated vascular cell dysfunction and TGF-β secretion

Background: Pentagalloyl glucose (PGG) is a polyphenol with vasoprotective properties. Targeted delivery of PGG reversed aortic aneurysm growth in several rodent models associated with decreased number of macrophages and transforming growth factor-β (TGF-β) expression. Thus, we sought to determine cellular mechanisms by which PGG reduces macrophage-induced aortic pathogenicity and its relationship to TGF-β. Methods: Using THP-1 cells, primary human aortic cells, and explanted rat aortas, we assessed the anti-inflammatory effect of PGG. Expression of pro/anti-inflammatory macrophage markers was analyzed. Adhesion of monocytes as well as oxidative stress status, viability, and TGF-β expression after primary aortic cell exposure to macrophage-conditioned medium with and without PGG were assessed. The release of TGF-β was also examined in elastase-treated cultured rat aortas. Results: PGG pre-treatment of human aortic cell monolayers reduced the adhesion of THP-1 monocytes. PGG enhanced the expression of anti-inflammatory markers in THP-1-derived macrophages, and increased mitochondrial reactive oxygen species as well as mitochondrial polarization. Conditioned medium from THP-1-derived macrophages induced reactive oxygen species, cell death, and TGF-β release from human aortic cells, which was suppressed by PGG. In explanted rat aortas, PGG reduced elastase mediated TGF-β release. Conclusions: Combining anti-inflammatory, cytotoxic, and oxidative effects, PGG has high cardiovascular therapeutic potential. We confirmed previous in vivo observations whereby PGG suppressed TGF-β response associated with disease resolution.

Macrophage polarization in inflammatory bowel disease

The growing prevalence of inflammatory bowel disease (IBD) has encouraged research efforts, which have contributed to gradual improvements in our understanding of IBD diagnosis and therapeutic approaches. The pathogenesis of IBD has not been fully elucidated; however, the combined actions of environmental, genetic, immune factors, and microbial organisms are believed to cause IBD. In the innate immune system, macrophages play important roles in maintaining intestinal health and in the development of IBD. Macrophages can be polarized from M0 into several phenotypes, among which M1 and M2 play critical roles in IBD development and the repair of intestinal homeostasis and damage. Certain macrophage-related IBD studies already exist; however, the functions of each phenotype have not been fully elucidated. As technology develops, understanding the link between macrophages and IBD has increased, including the growing knowledge of the developmental origins of intestinal macrophages and their performance of comprehensive functions. This review describes macrophage polarization in IBD from the perspectives of macrophage development and polarization, macrophage changes in homeostasis and IBD, metabolic changes, and the mechanisms of macrophage polarization in IBD. The discussion of these topics provides new insights into immunotherapy strategies for IBD. Video Abstract.

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.

KATP channels are regulators of programmed cell death and targets for the creation of novel drugs against ischemia/reperfusion cardiac injury

BACKGROUND

The use of percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) is associated with a mortality rate of 5%-7%. It is clear that there is an urgent need to develop new drugs that can effectively prevent cardiac reperfusion injury. ATP-sensitive K+ (KATP ) channel openers (KCOs) can be classified as such drugs.

RESULTS

KCOs prevent irreversible ischemia and reperfusion injury of the heart. KATP channel opening promotes inhibition of apoptosis, necroptosis, pyroptosis, and stimulation of autophagy. KCOs prevent the development of cardiac adverse remodeling and improve cardiac contractility in reperfusion. KCOs exhibit antiarrhythmic properties and prevent the appearance of the no-reflow phenomenon in animals with coronary artery occlusion and reperfusion. Diabetes mellitus and a cholesterol-enriched diet abolish the cardioprotective effect of KCOs. Nicorandil, a KCO, attenuates major adverse cardiovascular event and the no-reflow phenomenon, reduces infarct size, and decreases the incidence of ventricular arrhythmias in patients with acute myocardial infarction.

CONCLUSION

The cardioprotective effect of KCOs is mediated by the opening of mitochondrial KATP (mitoKATP ) and sarcolemmal KATP (sarcKATP ) channels, triggered free radicals' production, and kinase activation.

Tumor cell-derived spermidine promotes a pro-tumorigenic immune microenvironment in glioblastoma via CD8+ T cell inhibition

The glioblastoma microenvironment is enriched in immunosuppressive factors that potently interfere with the function of cytotoxic T lymphocytes. Cancer cells can directly impact the immune system, but the mechanisms driving these interactions are not completely clear. Here we demonstrate that the polyamine metabolite spermidine is elevated in the glioblastoma tumor microenvironment. Exogenous administration of spermidine drives tumor aggressiveness in an immune-dependent manner in pre-clinical mouse models via reduction of CD8+ T cell frequency and phenotype. Knockdown of ornithine decarboxylase, the rate-limiting enzyme in spermidine synthesis, did not impact cancer cell growth in vitro but did result in extended survival. Furthermore, glioblastoma patients with a more favorable outcome had a significant reduction in spermidine compared to patients with a poor prognosis. Our results demonstrate that spermidine functions as a cancer cell-derived metabolite that drives tumor progression by reducing CD8+T cell number and function.

Itaconate inhibits SYK through alkylation and suppresses inflammation against hvKP induced intestinal dysbiosis

Hypervirulent Klebsiella pneumoniae (hvKP) is a highly lethal opportunistic pathogen that elicits more severe inflammatory responses compared to classical Klebsiella pneumoniae (cKP). In this study, we investigated the interaction between hvKP infection and the anti-inflammatory immune response gene 1 (IRG1)-itaconate axis. Firstly, we demonstrated the activation of the IRG1-itaconate axis induced by hvKP, with a dependency on SYK signaling rather than STING. Importantly, we discovered that exogenous supplementation of itaconate effectively inhibited excessive inflammation by directly inhibiting SYK kinase at the 593 site through alkylation. Furthermore, our study revealed that itaconate effectively suppressed the classical activation phenotype (M1 phenotype) and macrophage cell death induced by hvKP. In vivo experiments demonstrated that itaconate administration mitigated hvKP-induced disturbances in intestinal immunopathology and homeostasis, including the restoration of intestinal barrier integrity and alleviation of dysbiosis in the gut microbiota, ultimately preventing fatal injury. Overall, our study expands the current understanding of the IRG1-itaconate axis in hvKP infection, providing a promising foundation for the development of innovative therapeutic strategies utilizing itaconate for the treatment of hvKP infections.

Spermidine Ameliorates Colitis via Induction of Anti-Inflammatory Macrophages and Prevention of Intestinal Dysbiosis

BACKGROUND AND AIMS

Exacerbated immune activation, intestinal dysbiosis and a disrupted intestinal barrier are common features among inflammatory bowel disease [IBD] patients. The polyamine spermidine, which is naturally present in all living organisms, is an integral component of the human diet, and exerts beneficial effects in human diseases. Here, we investigated whether spermidine treatment ameliorates intestinal inflammation and offers therapeutic potential for IBD treatment.

METHODS

We assessed the effect of oral spermidine administration on colitis severity in the T cell transfer colitis model in Rag2-/- mice by endoscopy, histology and analysis of markers of molecular inflammation. The effects on the intestinal microbiome were determined by 16S rDNA sequencing of mouse faeces. The impact on intestinal barrier integrity was evaluated in co-cultures of patient-derived macrophages with intestinal epithelial cells.

RESULTS

Spermidine administration protected mice from intestinal inflammation in a dose-dependent manner. While T helper cell subsets remained unaffected, spermidine promoted anti-inflammatory macrophages and prevented the microbiome shift from Firmicutes and Bacteroides to Proteobacteria, maintaining a healthy gut microbiome. Consistent with spermidine as a potent activator of the anti-inflammatory molecule protein tyrosine phosphatase non-receptor type 2 [PTPN2], its colitis-protective effect was dependent on PTPN2 in intestinal epithelial cells and in myeloid cells. The loss of PTPN2 in epithelial and myeloid cells, but not in T cells, abrogated the barrier-protective, anti-inflammatory effect of spermidine and prevented the anti-inflammatory polarization of macrophages.

CONCLUSION

Spermidine reduces intestinal inflammation by promoting anti-inflammatory macrophages, maintaining a healthy microbiome and preserving epithelial barrier integrity in a PTPN2-dependent manner.

NAD+ salvage governs the immunosuppressive capacity of mesenchymal stem cells

Mesenchymal stem/stromal cells (MSCs) possess robust immunoregulatory functions and are promising therapeutics for inflammatory disorders. This capacity is not innate but is activated or 'licensed' by inflammatory cytokines. The licensing mechanism remains unclear. Here, we examined whether inflammatory cytokines metabolically reprogrammed MSCs to confer this immunoregulatory capacity. In response to stimulation by inflammatory cytokines, MSCs exhibited a dramatic increase in the consumption of glucose, which was accompanied by an enhanced use of nicotinamide adenine dinucleotide (NAD+) and increased expression of nicotinamide phosphoribosyltransferase (NAMPT), a central enzyme in the salvage pathway for NAD+ production. When NAD+ synthesis was blocked by inhibiting or depleting NAMPT, the immunosuppressive function of MSCs induced by inflammatory cytokines was greatly attenuated. Consequently, when NAD+ metabolism in MSCs was perturbed, their therapeutic benefit was decreased in mice suffering from inflammatory bowel disease and acute liver injury. Further analysis revealed that NAMPT-driven production of NAD+ was critical for the inflammatory cytokine-induced increase in glycolysis in MSCs. Furthermore, the increase in glycolysis led to succinate accumulation in the tricarboxylic acid cycle, which led to hypoxia-inducible factor 1α (HIF-1α) stabilization and subsequently increased the transcription of key glycolytic genes, thereby persistently maintaining glycolytic flux. This study demonstrated that unlike its proinflammatory role in immune cells, NAD+ metabolism governs the anti-inflammatory function of MSCs during inflammation.

Functional polarization of tumor-associated macrophages dictated by metabolic reprogramming

Macrophages are highly plastic in different tissues and can differentiate into functional subpopulations under different stimuli. Tumor-associated macrophages (TAMs) are one of the most important innate immune cells implicated in the establishment of an immunosuppressive tumor microenvironment (TME). Recent evidence pinpoints the critical role of metabolic reprogramming in dictating pro-tumorigenic functions of TAMs. Both tumor cells and macrophages undergo metabolic reprogramming to meet energy demands in the TME. Understanding the metabolic rewiring in TAMs can shed light on immune escape mechanisms and provide insights into repolarizing TAMs towards anti-tumorigenic function. Here, we discuss how metabolism impinges on the functional divergence of macrophages and its relevance to macrophage polarization in the TME.

Type 1 diabetes mellitus: Inflammation, mitophagy, and mitochondrial function

Type 1 diabetes mellitus (T1DM) is a T-cell-mediated autoimmune disease characterized by the damage of insulin-secreting β-cells in the pancreatic islets of Langerhans. To date, its etiology is not fully understood, despite decades of active search for root causes, and that underlines the complexity of the disease pathogenesis. It was found that mitophagy plays a regulatory role in the development of autoimmune response during T1DM pathogenesis by preventing the accumulation of defective/dysfunctional mitochondria in pancreatic cells. Mitochondrial dysfunction due to impaired mitophagy with the release of mitochondrial reactive oxygen species (mtROS) and mitochondrial DNA (mtDNA) contributes to initiating an inflammatory response by elevating pro-inflammatory cytokines and interacting with receptors like those involved in the pathogen-associated response. Moreover, mtROS and mtDNA activate pathways leading to the development of chronic inflammation, which is tightly implicated in T1DM autoimmunity. In this review, we summarized the evidence highlighting the functional role of mitophagy and mitochondria in the development of immune response and chronic inflammation during T1DM pathogenesis. Several anti-inflammatory and mitophagy-related treatment options have been explored.

Biochemical and molecular inducers and modulators of M2 macrophage polarization in clinical perspective

Macrophages as innate immune cells with great plasticity are of great interest for cell therapy. There are two main macrophage populations - pro- and anti-inflammatory cells also known as M1 and M2. High potential in cancer research contributed to the in-depth study of the molecular processes leading to the polarization of macrophages into the M1 phenotype, and much less attention has been paid to anti-inflammatory M2 macrophages, which can be successfully used in cell therapy of inflammatory diseases. This review describes ontogenesis of macrophages, main functions of pro- and and-inflammatory cells and four M2 subpopulations characterized by different functionalities. Data on agents (cytokines, microRNAs, drugs, plant extracts) that may induce M2 polarization through the changes in microenvironment, metabolism, and efferocytosis are summarized. Finally, recent attempts at stable macrophage polarization using genetic modifications are described. This review may be helpful for researchers concerned with the problem of M2 macrophage polarization and potential use of these anti-inflammatory cells for the purposes of regenerative medicine.

Harnessing metabolism of hepatic macrophages to aid liver regeneration

Liver regeneration is a dynamic and regulated process that involves inflammation, granulation, and tissue remodeling. Hepatic macrophages, abundantly distributed in the liver, are essential components that actively participate in each step to orchestrate liver regeneration. In the homeostatic liver, resident macrophages (Kupffer cells) acquire a tolerogenic phenotype and contribute to immunological tolerance. Following toxicity-induced damage or physical resection, Kupffer cells as well as monocyte-derived macrophages can be activated and promote an inflammatory process that supports the survival and activation of hepatic myofibroblasts and thus promotes scar tissue formation. Subsequently, these macrophages, in turn, exhibit the anti-inflammatory effects critical to extracellular matrix remodeling during the resolution stage. However, continuous damage-induced chronic inflammation generally leads to hepatic macrophage dysfunction, which exacerbates hepatocellular injury and triggers further liver fibrosis and even cirrhosis. Emerging macrophage-targeting strategies have shown efficacy in both preclinical and clinical studies. Increasing evidence indicates that metabolic rewiring provides substrates for epigenetic modification, which endows monocytes/macrophages with prolonged "innate immune memory". Therefore, it is reasonable to conceive novel therapeutic strategies for metabolically reprogramming macrophages and thus mediate a homeostatic or reparative process for hepatic inflammation management and liver regeneration.

Immunometabolism changes in fibrosis: from mechanisms to therapeutic strategies

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

Gut microbiota and anti-aging: Focusing on spermidine

The human gut microbiota plays numerous roles in regulating host growth, the immune system, and metabolism. Age-related changes in the gut environment lead to chronic inflammation, metabolic dysfunction, and illness, which in turn affect aging and increase the risk of neurodegenerative disorders. Local immunity is also affected by changes in the gut environment. Polyamines are crucial for cell development, proliferation, and tissue regeneration. They regulate enzyme activity, bind to and stabilize DNA and RNA, have antioxidative properties, and are necessary for the control of translation. All living organisms contain the natural polyamine spermidine, which has anti-inflammatory and antioxidant properties. It can regulate protein expression, prolong life, and improve mitochondrial metabolic activity and respiration. Spermidine levels experience an age-related decrease, and the development of age-related diseases is correlated with decreased endogenous spermidine concentrations. As more than just a consequence, this review explores the connection between polyamine metabolism and aging and identifies advantageous bacteria for anti-aging and metabolites they produce. Further research is being conducted on probiotics and prebiotics that support the uptake and ingestion of spermidine from food extracts or stimulate the production of polyamines by gut microbiota. This provides a successful strategy to increase spermidine levels.

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

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

Development of an Immune Prognostic Model for Clear Cell Renal Cell Carcinoma Based on Tumor Microenvironment

Immune infiltration remains at a high level in clear cell renal cell carcinoma (ccRCC). It has been confirmed that immune cell infiltration in tumor microenvironment (TME) is intimately bound up with the progression and the clinical outcome of ccRCC. The prognostic model, developed based on different immune subtypes of ccRCC, has a predictive value in patients' prognosis. RNA sequencing data, somatic mutation data of ccRCC and clinical information were acquired from the cancer genome atlas (TCGA) database. The key immune-related genes (IRGs) were selected and by univariate Cox, LASSO, and multivariate Cox regression analyses. Then the ccRCC prognostic model was developed. The applicability of this model was verified in the independent dataset GSE29609. Thirteen IRGs including CCL7, ATP6V1C2, ATP2B3, ELAVL2, SLC22A8, DPP6, EREG, SERPINA7, PAGE2B, ADCYAP1, ZNF560, MUC20, and ANKRD30A were finally selected and a 13-IRGs prognostic model was developed. Survival analysis demonstrated that when compared with the low-risk group, patients in the high-risk group had a lower overall survival (p<0.05). AUC values based on the 13-IRGs prognostic model used to predict 3- and 5-year survival of ccRCC patients were greater than 0.70. And risk score was an independent prognostic factor (p<0.001). In addition, nomogram could accurately predict ccRCC patient's prognosis. This 13-IRGs model can effectively evaluate the prognosis of ccRCC patients, and also provide guidance for the treatment and prognosis of ccRCC patients.

Natural Mitochondria Targeting Substances and Their Effect on Cellular Antioxidant System as a Potential Benefit in Mitochondrial Medicine for Prevention and Remediation of Mitochondrial Dysfunctions

Based on the knowledge that many diseases are caused by defects in the metabolism of the cells and, in particular, in defects of the mitochondria, mitochondrial medicine starts precisely at this point. This new form of therapy is used in numerous fields of human medicine and has become a central focus within the field of medicine in recent years. With this form of therapy, the disturbed cellular energy metabolism and an out-of-balance antioxidant system of the patient are to be influenced to a greater extent. The most important tool here is mitotropic substances, with the help of which attempts are made to compensate for existing dysfunction. In this article, both mitotropic substances and accompanying studies showing their efficacy are summarized. It appears that the action of many mitotropic substances is based on two important properties. First, on the property of acting antioxidantly, both directly as antioxidants and via activation of downstream enzymes and signaling pathways of the antioxidant system, and second, via enhanced transport of electrons and protons in the mitochondrial respiratory chain.