Macrophages with a deletion of the phosphoenolpyruvate carboxykinase 1 (Pck1) gene have a more proinflammatory phenotype

New insights on metabolic reprogramming in macrophage plasticity

Macrophages are the first line of defense in the innate immune system. Macrophages have two subtypes: classically activated macrophages (M1) and alternatively activated macrophages (M2), with different phenotypes and functions. They play a critical role in defending against pathogens and maintaining internal homeostasis. Macrophages have great plasticity in their biological characteristics. Although the regulation of macrophage plasticity has not been fully elucidated, accumulated evidence supports that microenvironmental differences are the root cause for macrophage differentiation into different subtypes. These differences alter macrophage plasticity by modulating key metabolites, activating downstream gene transcription, and influencing phagocytosis, cytokine secretion, and immune regulation. Herein, we systematically summarize metabolic reprogramming, including glucose, lipid, amino acid, ion, vitamin, nucleotide, and butyrate metabolism, as key regulators affecting macrophage polarization, providing new insights for developing targeted drugs that modulate macrophage plasticity.

The neglected PCK1/glucagon (inter)action in nutrient homeostasis beyond gluconeogenesis: Disease pathogenesis and treatment

BACKGROUND

Glucagon plays a central role in hepatic adaptation during fasting, with the upregulation of hepatic phosphoenolpyruvate carboxykinase 1 (PCK1) traditionally associated with increased gluconeogenesis. However, recent experimental models and clinical studies have challenged this view, suggesting a more complex interplay between PCK1 and glucagon, which extends beyond gluconeogenesis and has broader implications for metabolic regulation in health and disease.

SCOPE OF REVIEW

This review provides a comprehensive overview of the current evidence on the multifaceted roles of PCK1 in glucagon-dependent hepatic adaptation during fasting, which is crucial for maintaining systemic homeostasis not only of glucose, but also of lipids and amino acids. We explore the relationship between PCK1 deficiency and glucagon resistance in metabolic disorders, including inherited PCK1 deficiency and metabolic dysfunction-associated steatotic liver disease (MASLD), and compare findings from experimental animal models with whole-body or tissue-specific ablation of PCK1 or the glucagon receptor. We propose new research platforms to advance the therapeutic potential of targeting PCK1 in metabolic diseases.

MAJOR CONCLUSIONS

We propose that hepatic PCK1 deficiency might be an acquired metabolic disorder linking alterations in lipid metabolism with impaired glucagon signaling. Our findings highlight interesting links between glycerol, PCK1 deficiency, elevated plasma alanine levels and glucagon resistance. We conclude that the roles of PCK1 and glucagon in metabolic regulation are more complex than previously assumed. In this (un)expected scenario, hepatic PCK1 deficiency and glucagon resistance appear to exert limited control over glycemia, but have broader metabolic effects related to lipid and amino acid dysregulation. Given the shift in glucagon research from receptor inhibition to activation, we propose that a similar paradigm shift is needed in the study of hepatic PCK1. Understanding PCK1 expression and activity in the glucagon-dependent hepatic adaptation to fasting might provide new perspectives and therapeutic opportunities for metabolic diseases.

Apabetalone alleviates ligature-induced periodontitis by inhibiting M1 macrophage polarization via an immunometabolic shift

OBJECTIVES

To explore the effects and biological mechanism of apabetalone on periodontal inflammation by regulating glycolysis and metabolites.

METHODS

A ligature-induced periodontitis model was established in mice and apabetalone was administered on the ligation silk for two weeks. Inflammation levels and alveolar bone absorption were explored using micro-computed tomography and histopathological analysis. To observe the role of apabetalone in macrophage polarization and the macrophage-mediated immune microenvironment, a Luminex assay, quantitative real-time polymerase chain reaction, a conditioned medium experiment, a Seahorse extracellular flux assay and quantitative metabolomics were used for molecular biological analysis.

RESULTS

Apabetalone-treated mice exhibited ameliorated alveolar bone loss and inflammatory infiltration in the periodontium. Furthermore, apabetalone significantly inhibited the production of proinflammatory cytokines and suppressed the levels of M1-specific biomarkers both in vivo and in vitro. Apabetalone also promoted the osteogenic potential of mouse periodontal ligament cells in a macrophage-mediated microenvironment. Apabetalone restrained LPS-induced glucose uptake and lactic acid production. Apabetalone inhibited glycolysis by suppressing the transcription and protein expression of hexokinase 2, glucose transporter 1 and phosphofructokinase-2/fructose-2,6- bisphosphatase 3 (PFKFB3) in a dose-dependent manner. Quantitative analysis of certain carbohydrates involved in energy metabolism revealed that apabetalone reserved the disruption of the tricarboxylic acid (TCA) cycle and inhibited glycolysis and the pentose phosphate pathway. In addition, apabetalone increased the oxygen consumption rate.

CONCLUSION

Collectively, these findings indicate that apabetalone improves the periodontal immune microenvironment by regulating metabolites in macrophages. Apabetalone exerts anti-inflammatory and osteo-protective effects by replenishing the broken TCA cycle and suppressing glycolysis. Apabetalone is a potential candidate for the treatment of periodontitis.

PCK1 as a target for cancer therapy: from metabolic reprogramming to immune microenvironment remodeling

Recently, changes in metabolites and metabolism-related enzymes related to tumor cell proliferation, metastasis, drug resistance, and immunosuppression have become a research hotspot, and researchers have attempted to determine the clinical correlation between specific molecular lesions and metabolic phenotypes. Convincing evidence shows that metabolic reprogramming is closely related to the proliferation, invasion, metastasis, and poor prognosis of malignant tumors. Therefore, targeting metabolic reprogramming is a new direction for cancer treatment. However, how molecular alterations in tumors contribute to metabolic diversity and unique targeting dependencies remains unclear. A full understanding of the underlying mechanisms of metabolic reprogramming in cancer may lead to better identification of therapeutic targets and the development of therapeutic strategies. Evidence for the importance of PCK1, a phosphoenolpyruvate carboxykinase 1, in tumorigenesis and development is accumulating. PCK1 can regulate cell proliferation and metastasis by remodeling cell metabolism. Additionally, PCK1 has "nonclassical" nonmetabolic functions, involving the regulation of gene expression, angiogenesis, epigenetic modification, and other processes, and has an impact on cell survival, apoptosis, and other biological activities, as well as the remodeling of the tumor immune microenvironment. Herein, we provide a comprehensive overview of the functions of PCK1 under physiological and pathological conditions and suggest that PCK1 is a potential target for cancer therapy. We also propose a future exploration direction for targeting PCK1 for cancer therapy from a clinical perspective. Finally, in view of the collective data, the results of our discussion suggest the potential clinical application of targeted PCK1 therapy in combination with chemotherapy and immunotherapy for cancer treatment.

Combinatorial macrophage induced innate immunotherapy against Ewing sarcoma: Turning "Two Keys" simultaneously

BACKGROUND

Macrophages play important roles in phagocytosing tumor cells. However, tumors escape macrophage phagocytosis in part through the expression of anti-phagocytic signals, most commonly CD47. In Ewing sarcoma (ES), we found that tumor cells utilize dual mechanisms to evade macrophage clearance by simultaneously over-expressing CD47 and down-regulating cell surface calreticulin (csCRT), the pro-phagocytic signal. Here, we investigate the combination of a CD47 blockade (magrolimab, MAG) to inhibit the anti-phagocytic signal and a chemotherapy regimen (doxorubicin, DOX) to enhance the pro-phagocytic signal to induce macrophage phagocytosis of ES cells in vitro and inhibit tumor growth and metastasis in vivo.

METHODS

Macrophages were derived from human peripheral blood monocytes by granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF). Flow cytometry- and microscopy-based in-vitro phagocytosis assays were performed to evaluate macrophage phagocytosis of ES cells. Annexin-V assay was performed to evaluate apoptosis. CD47 was knocked out by CRISPR/Cas9 approach. ES cell-based and patient-derived-xenograft (PDX)-based mouse models were utilized to assess the effects of MAG and/or DOX on ES tumor development and animal survival. RNA-Seq combined with CIBERSORTx analysis was utilized to identify changes in tumor cell transcriptome and tumor infiltrating immune cell profiling in MAG and/or DOX treated xenograft tumors.

RESULTS

We found that MAG significantly increased macrophage phagocytosis of ES cells in vitro (p < 0.01) and had significant effect on reducing tumor burden (p < 0.01) and increasing survival in NSG mouse model (p < 0.001). The csCRT level on ES cells was significantly enhanced by DOX in a dose- and time-dependent manner (p < 0.01). Importantly, DOX combined with MAG significantly enhanced macrophage phagocytosis of ES cells in vitro (p < 0.01) and significantly decreased tumor burden (p < 0.01) and lung metastasis (p < 0.0001) and extended animal survival in vivo in two different mouse models of ES (p < 0.0001). Furthermore, we identified CD38, CD209, CD163 and CD206 as potential markers for ES-phagocytic macrophages. Moreover, we found increased M2 macrophage infiltration and decreased expression of Cd209 in the tumor microenvironment of MAG and DOX combinatorial therapy treated tumors.

CONCLUSIONS

By turning "two keys" simultaneously to reactivate macrophage phagocytic activity, our data demonstrated an effective and highly translatable alternative therapeutic approach utilizing innate (tumor associated macrophages) immunotherapy against high-risk metastatic ES.

Machine learning-based B cell-related diagnostic biomarker signature and molecular subtypes characteristic of ulcerative colitis

As an inflammatory bowel disease, ulcerative colitis (UC) does not respond well to current treatments. It is of positive clinical significance to further study the pathogenesis of UC and find new therapeutic targets. B lymphocytes play an important role in the pathogenesis of UC. The effect of anti-CD20 therapy on UC also provides new evidence for the involvement of B cells in UC process additionally, suggesting the important role and potential therapeutic value of B cells in UC. In this study, we screened the most critical immune cell-related gene modules associated with UC and found that activated B cells were closely related to the gene modules. Subsequently, key activated B cell-associated gene (BRG) signatures were obtained based on WGCNA and differential expression analysis, and three overlapping BRG-associated genes were obtained by RF and LASSO algorithms as BRG-related diagnostic biomarkers for UC. Nomogram model was further performed to evaluate the diagnostic ability of BRG-related diagnostic biomarkers, subsequently followed by UC molecular subsets identification and immunoinfiltration analysis. We also further verified the expressions of the three screened BRGs in vitro by using an LPS-induced NCM460 cell line model. Our results provide new evidence and potential intervention targets for the role of B cells in UC from a new perspective.

Aloe vera peel-derived nanovesicles display anti-inflammatory properties and prevent myofibroblast differentiation

BACKGROUND

Aloe vera (AV) is a medicinal plant, most known for its beneficial effects on a variety of skin conditions. Its known active compounds include carbohydrates and flavonoids such as quercetin and kaempferol, among others. In the past decade, plant nanovesicles (NVs) have gained considerable interest as interkingdom communicators, presenting an opportunity for clinical standardization of natural products. In this study, we aimed to assess the potential of AVpNVs for the treatment of burn wounds.

METHODS

AVpNVs were isolated and characterized regarding vesicle yield (nanoparticle tracking analysis) and structure (transmission electron microscopy and atomic force microscopy), as well as their protein content with proteomics. We assessed key characteristics for treating burn wounds in vitro, such as the anti-inflammatory potential in LPS-stimulated macrophages and keratinocytes, and the effect of AVpNVs on myofibroblast differentiation and contraction.

KEY FINDINGS

AVpNVs presented a homogenous NV population, vesicular shape, and NV-associated protein markers. AVpNVs significantly decreased the secretion of pro-inflammatory cytokines TNFα, IL-1β, and IL-6. Furthermore, AVpNVs inhibited myofibroblast differentiation and significantly decreased their contractile potential in collagen matrices. Observed effects were linked to proteins identified in the isolates through proteomics analysis.

CONCLUSION

AVpNVs displayed characteristics as an inflammatory modulator, while simultaneously diminishing myofibroblast differentiation and contraction. Novel strategies for burn wound treatment seek to decrease scarring on a cellular and molecular level in the early stages of wound healing, which makes AVpNVs a promising candidate for future plant-vesicle-based treatments.

Role of phosphoenolpyruvate carboxykinase 1 (pck1) in mediating nutrient metabolism in zebrafish

Carbohydrates are the most economical source of energy in fish feeds, but most fish have limited ability to utilize carbohydrates. It has been reported that phosphoenolpyruvate carboxykinase 1 (pck1) is involved in carbohydrate metabolism, lipid metabolism, and other metabolic processes. However, direct evidence is lacking to fully understand the relationship between pck1 and glucose and lipid metabolism. Here, we generated a pck1 knockout zebrafish by CRISPR/cas9 system, and a high-carbohydrate diet was provided to 60 days post-fertilization (dpf) for 8 weeks. We found that pck1-deficient zebrafish displayed decreased plasma glucose, elevated mRNA levels of glycolysis-related genes (gck, pfk, pk), and reduced the transcriptional levels of gluconeogenic genes (pck1, fbp1a) in liver. We also found decreased triglyceride, total cholesterol, and lipid accumulation and in pck1^-/- zebrafish, along with downregulation of genes for lipolysis (acaca) and lipogenesis (cpt1). In addition, the observation of HE staining revealed that the total muscle area of pck1^-/- was substantially less than that of WT zebrafish and real-time PCR suggested that GH/IGF-1 signaling (ulk2, stat1b) may be suppressed in pck1-deficient fish. Taken together, these findings suggested that pck1 may play an important role in the high-carbohydrate diet utilization of fish and significantly affected lipid metabolism and protein synthesis in zebrafish. pck1 knockout mutant line could facilitate a further mechanism study of pck1-associated metabolic regulation and provide new information for improving carbohydrate utilization traits.

Mitochondrial VDAC1: A Potential Therapeutic Target of Inflammation-Related Diseases and Clinical Opportunities

The multifunctional protein, voltage-dependent anion channel 1 (VDAC1), is located on the mitochondrial outer membrane. It is a pivotal protein that maintains mitochondrial function to power cellular bioactivities via energy generation. VDAC1 is involved in regulating energy production, mitochondrial oxidase stress, Ca²⁺ transportation, substance metabolism, apoptosis, mitochondrial autophagy (mitophagy), and many other functions. VDAC1 malfunction is associated with mitochondrial disorders that affect inflammatory responses, resulting in an up-regulation of the body’s defensive response to stress stimulation. Overresponses to inflammation may cause chronic diseases. Mitochondrial DNA (mtDNA) acts as a danger signal that can further trigger native immune system activities after its secretion. VDAC1 mediates the release of mtDNA into the cytoplasm to enhance cytokine levels by activating immune responses. VDAC1 regulates mitochondrial Ca²⁺ transportation, lipid metabolism and mitophagy, which are involved in inflammation-related disease pathogenesis. Many scientists have suggested approaches to deal with inflammation overresponse issues via specific targeting therapies. Due to the broad functionality of VDAC1, it may become a useful target for therapy in inflammation-related diseases. The mechanisms of VDAC1 and its role in inflammation require further exploration. We comprehensively and systematically summarized the role of VDAC1 in the inflammatory response, and hope that our research will lead to novel therapeutic strategies that target VDAC1 in order to treat inflammation-related disorders.

Comparative transcriptome profiling reveals a network of differentially expressed genes in Asia II 7 and MEAM1 whitefly cryptic species in response to early infection of Cotton leaf curl Multan virus

Cotton leaf curl Multan virus (CLCuMuV) is a whitefly-vectored begomovirus that poses ramping threat to several economically important crops worldwide. The differential transmission of CLCuMuV by its vector Bemisia tabaci mainly relies on the type of whitefly cryptic species. However, the molecular responses among different whitefly cryptic species in response to early CLCuMuV infection remain elusive. Here, we compared early-stage transcriptomic profiles of Asia II 7 and MEAM1 cryptic species infected by CLCuMuV. Results of Illumina sequencing revealed that after 6 and 12 h of CLCuMuV acquisition, 153 and 141 genes among viruliferous (VF) Asia II 7, while 445 and 347 genes among VF MEAM 1 whiteflies were differentially expressed compared with aviruliferous (AVF) whiteflies. The most abundant groups of differentially expressed genes (DEGs) among Asia II 7 and MEAM1 were associated with HTH-1 and zf-C2H2 classes of transcription factors (TFs), respectively. Notably, in contrast to Asia II 7, MEAM1 cryptic species displayed higher transcriptional variations with elevated immune-related responses following CLCuMuV infection. Among both cryptic species, we identified several highly responsive candidate DEGs associated with antiviral innate immunity (alpha glucosidase, LSM14-like protein B and phosphoenolpyruvate carboxykinase), lysosome (GPI-anchored protein 58) and autophagy/phagosome pathways (sequestosome-1, cathepsin F-like protease), spliceosome (heat shock protein 70), detoxification (cytochrome P450 4C1), cGMP-PKG signaling pathway (myosin heavy chain), carbohydrate metabolism (alpha-glucosidase), biological transport (mitochondrial phosphate carrier) and protein absorption and digestion (cuticle protein 8). Further validation of RNA-seq results showed that 23 of 28 selected genes exhibited concordant expression both in RT-qPCR and RNA-seq. Our findings provide vital mechanistic insights into begomovirus-whitefly interactions to understand the dynamics of differential begomovirus transmission by different whitefly cryptic species and reveal novel molecular targets for sustainable management of insect-transmitted plant viruses.

Glycometabolism Reprogramming of Glial Cells in Central Nervous System: Novel Target for Neuropathic Pain

Neuropathic pain is characterized by hyperalgesia and allodynia. Inflammatory response is conducive to tissue recovery upon nerve injury, but persistent and exaggerated inflammation is detrimental and participates in neuropathic pain. Synaptic transmission in the nociceptive pathway, and particularly the balance between facilitation and inhibition, could be affected by inflammation, which in turn is regulated by glial cells. Importantly, glycometabolism exerts a vital role in the inflammatory process. Glycometabolism reprogramming of inflammatory cells in neuropathic pain is characterized by impaired oxidative phosphorylation in mitochondria and enhanced glycolysis. These changes induce phenotypic transition of inflammatory cells to promote neural inflammation and oxidative stress in peripheral and central nervous system. Accumulation of lactate in synaptic microenvironment also contributes to synaptic remodeling and central sensitization. Previous studies mainly focused on the glycometabolism reprogramming in peripheral inflammatory cells such as macrophage or lymphocyte, little attention was paid to the regulation effects of glycometabolism reprogramming on the inflammatory responses in glial cells. This review summarizes the evidences for glycometabolism reprogramming in peripheral inflammatory cells, and presents a small quantity of present studies on glycometabolism in glial cells, expecting to promote the exploration in glycometabolism in glial cells of neuropathic pain.

LncRNA-miRNA-mRNA Network Analysis Reveals the Potential Biomarkers in Crohn's Disease Rats Treated with Herb-Partitioned Moxibustion

BACKGROUND

Long noncoding RNA (lncRNA) is receiving growing attention in Crohn's disease (CD). However, the mechanism by which herb-partitioned moxibustion (HPM) regulates the expression and functions of lncRNAs in CD rats is still unclear. The aim of our study is to identify lncRNA-miRNA-mRNA network potential biological functions in CD.

METHODS

RNA sequencing and microRNA (miRNA) sequencing were carried out to analyze lncRNA, miRNA and mRNA expression profiles among the CD rats, normal control rats, and CD rats after HPM treatment and constructed the potential related lncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) networks. Then, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, protein-protein interaction (PPI) analysis and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to explore potentially important genes in ceRNA networks.

RESULTS

A total of 189 lncRNAs, 32 miRNAs and 463 mRNAs were determined as differentially expressed (DE) genes in CD rats compared to normal control rats, and 161 lncRNAs, 12 miRNAs and 130 mRNAs were identified as remarkably DE genes in CD rats after HPM treatment compared to CD rats. GO analysis indicated that the target genes were most enriched in cAMP and in KEGG pathway analysis the main pathways included adipocytokine, PPAR, AMPK, FoxO and PI3K-Akt signaling pathway. Finally, qRT-PCR results confirmed that lncRNA LOC102550026 sponged miRNA-34c-5p to regulate the intestinal immune inflammatory response by targeting Pck1.

CONCLUSION

By constructing a ceRNA network with lncRNA-miRNA-mRNA, PCR verification, and KEGG analysis, we revealed that LOC102550026/miRNA-34c-5p/Pck1 axis and adipocytokine, PPAR, AMPK, FoxO, and PI3K-Akt signaling pathways might regulate the intestinal immune-inflammatory response, and HPM may regulate the lncRNA LOC102550026/miR-34c-5p/Pck1 axis and adipocytokine, PPAR, AMPK, FoxO, and PI3K-Akt signaling pathways, thus improving intestinal inflammation in CD. These findings may be novel potential targets in CD.

PCK1 dysregulation in cancer: Metabolic reprogramming, oncogenic activation, and therapeutic opportunities

The last few decades have witnessed an advancement in our understanding of multiple cancer cell pathways related to metabolic reprogramming. One of the most important cancer hallmarks, including aerobic glycolysis (the Warburg effect), the central carbon pathway, and multiple-branch metabolic pathway remodeling, enables tumor growth, progression, and metastasis. Phosphoenolpyruvate carboxykinase 1 (PCK1), a key rate-limiting enzyme in gluconeogenesis, catalyzes the conversion of oxaloacetate to phosphoenolpyruvate. PCK1 expression in gluconeogenic tissues is tightly regulated during fasting. In tumor cells, PCK1 is regulated in a cell-autonomous manner rather than by hormones or nutrients in the extracellular environment. Interestingly, PCK1 has an anti-oncogenic role in gluconeogenic organs (the liver and kidneys), but a tumor-promoting role in cancers arising from non-gluconeogenic organs. Recent studies have revealed that PCK1 has metabolic and non-metabolic roles in multiple signaling networks linking metabolic and oncogenic pathways. Aberrant PCK1 expression results in the activation of oncogenic pathways, accompanied by metabolic reprogramming, to maintain tumorigenesis. In this review, we summarize the mechanisms underlying PCK1 expression and regulation, and clarify the crosstalk between aberrant PCK1 expression, metabolic rewiring, and signaling pathway activation. In addition, we highlight the clinical relevance of PCK1 and its value as a putative cancer therapeutic target.

Chicoric Acid Prevents Neuroinflammation and Neurodegeneration in a Mouse Parkinson’s Disease Model: Immune Response and Transcriptome Profile of the Spleen and Colon

Chicoric acid (CA), a polyphenolic acid compound extracted from chicory and echinacea, possesses antiviral, antioxidative and anti-inflammatory activities. Growing evidence supports the pivotal roles of brain–spleen and brain–gut axes in neurodegenerative diseases, including Parkinson’s disease (PD), and the immune response of the spleen and colon is always the active participant in the pathogenesis and development of PD. In this study, we observe that CA prevented dopaminergic neuronal lesions, motor deficits and glial activation in PD mice, along with the increment in striatal brain-derived neurotrophic factor (BDNF), dopamine (DA) and 5-hydroxyindoleacetic acid (5-HT). Furthermore, CA reversed the level of interleukin-17(IL-17), interferon-gamma (IFN-γ) and transforming growth factor-beta (TGF-β) of PD mice, implicating its regulatory effect on the immunological response of spleen and colon. Transcriptome analysis revealed that 22 genes in the spleen (21 upregulated and 1 downregulated) and 306 genes (190 upregulated and 116 downregulated) in the colon were significantly differentially expressed in CA-pretreated mice. These genes were functionally annotated with GSEA, GO and KEGG pathway enrichment, providing the potential target genes and molecular biological mechanisms for the modulation of CA on the spleen and gut in PD. Remarkably, CA restored some gene expressions to normal level. Our results highlighted that the neuroprotection of CA might be associated with the manipulation of CA on brain–spleen and brain–gut axes in PD.

Mucosal Gene Transcript Signatures in Treatment Naïve Inflammatory Bowel Disease: A Comparative Analysis of Disease to Symptomatic and Healthy Controls in the European IBD-Character Cohort

Background

Studies of the mucosal transcriptomic landscape have given new insight into the pathogenesis of inflammatory bowel disease (IBD). Recently, the predictive biomarker potential of gene expression signatures has been explored. To further investigate the mucosal gene expression in IBD, we recruited a cohort of treatment naïve patients and compared them to both symptomatic and healthy controls.

Methods

Altogether, 323 subjects were included: Crohn’s disease (N = 75), ulcerative colitis (N = 87) and IBD unclassified (N = 3). Additionally, there were two control groups: symptomatic controls (N = 131) and healthy controls (N = 27). Mucosal biopsies were collected during ileocolonoscopy and gene expression in inflamed and non-inflamed mucosa was explored. Gene expression profiling was performed using Agilent G3 Human Gene Expression 860K v3 One-Color microarray. We recorded information about treatment escalation to anti-TNF agents or surgery, and anti-TNF response, to explore predictive opportunities of the mucosal transcriptome.

Results

Gene expression profiles in symptomatic controls in whom IBD had been excluded resembled that of IBD patients and diverged from that of healthy controls. In non-inflamed Crohn’s disease and ulcerative colitis, gene set enrichment analysis revealed dysregulation of pathways involved in basic cellular biological processes. Mitochondria-associated pathways were dysregulated both in non-inflamed and inflamed Crohn’s disease and ulcerative colitis (>2.6 normalized enrichment scores <−1.8). Gene expression signatures of Crohn’s disease and ulcerative colitis did not predict time for treatment escalation (p = 0.175). No significant association was found between gene expression signatures and anti-TNF response.

Conclusion

Non-inflamed samples are probably superior to inflamed samples when exploring gene expression signatures in IBD and might reveal underlying mechanisms central for disease initiation. The gene expression signatures of the control groups were related to if they were symptomatic or not, which may have important implications for future study designs.

Meta-Inflammation and Metabolic Reprogramming of Macrophages in Diabetes and Obesity: The Importance of Metabolites

Diabetes mellitus type II and obesity are two important causes of death in modern society. They are characterized by low-grade chronic inflammation and metabolic dysfunction (meta-inflammation), which is observed in all tissues involved in energy homeostasis. A substantial body of evidence has established an important role for macrophages in these tissues during the development of diabetes mellitus type II and obesity. Macrophages can activate into specialized subsets by cues from their microenvironment to handle a variety of tasks. Many different subsets have been described and in diabetes/obesity literature two main classifications are widely used that are also defined by differential metabolic reprogramming taking place to fuel their main functions. Classically activated, pro-inflammatory macrophages (often referred to as M1) favor glycolysis, produce lactate instead of metabolizing pyruvate to acetyl-CoA, and have a tricarboxylic acid cycle that is interrupted at two points. Alternatively activated macrophages (often referred to as M2) mainly use beta-oxidation of fatty acids and oxidative phosphorylation to create energy-rich molecules such as ATP and are involved in tissue repair and downregulation of inflammation. Since diabetes type II and obesity are characterized by metabolic alterations at the organism level, these alterations may also induce changes in macrophage metabolism resulting in unique macrophage activation patterns in diabetes and obesity. This review describes the interactions between metabolic reprogramming of macrophages and conditions of metabolic dysfunction like diabetes and obesity. We also focus on different possibilities of measuring a range of metabolites intra-and extracellularly in a precise and comprehensive manner to better identify the subsets of polarized macrophages that are unique to diabetes and obesity. Advantages and disadvantages of the currently most widely used metabolite analysis approaches are highlighted. We further describe how their combined use may serve to provide a comprehensive overview of the metabolic changes that take place intracellularly during macrophage activation in conditions like diabetes and obesity.

Phosphoenolpyruvate Carboxykinase (PCK) in the Brain Gluconeogenic Pathway Contributes to Oxidative and Lactic Injury After Stroke

To demonstrate the role of the rate-limiting and ATP-dependent gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PCK) in oxidative and lactic stress and the effect of phenothiazine on PCK after stroke, a total of 168 adult male Sprague Dawley rats (3 months old, 280-300 g) underwent 2-h intraluminal middle cerebral artery occlusion (MCAO) and reperfusion for 6, 24, 48 h, or 7 days. Phenothiazine (chlorpromazine and promethazine (C+P)) (8 mg/kg) and 3-mercaptopicolinic acid (3-MPA, a PCK inhibitor, 100 μM) were administered at reperfusion onset. The effects of phosphoenolpyruvate, 3-MPA, or PCK knockdown were studied in neuronal cultures subjected to oxygen/glucose deprivation. Reactive oxygen species, lactate, phosphoenolpyruvate (PEP; a gluconeogenic product), mRNA, and protein of total PCK, PCK-1, and PCK-2 increased after MCAO and oxygen-glucose deprivation (OGD). Oxaloacetate (a gluconeogenic substrate) decreased, while PEP and glucose were increased, suggesting reactive gluconeogenesis. These changes were attenuated by phenothiazine, 3-MPA, or PCK shRNA. PCK-1 and -2 existed primarily in neurons, while the effects of ischemic stroke on the PCK expression were seen predominately in astrocytes. Thus, phenothiazine reduced infarction and oxidative/lactic stress by inhibiting PCKs, leading to functional recovery.

Ulcerative colitis immune cell landscapes and differentially expressed gene signatures determine novel regulators and predict clinical response to biologic therapy

The heterogeneous pathobiology underlying Ulcerative Colitis (UC) is not fully understood. Using publicly available transcriptomes from adult UC patients, we identified the immune cell landscape, molecular pathways, and differentially expressed genes (DEGs) across patient cohorts and their association with treatment outcomes. The global immune cell landscape of UC tissue included increased neutrophils, T CD4 memory activated cells, active dendritic cells (DC), and M0 macrophages, as well as reduced trends in T CD8, Tregs, B memory, resting DC, and M2 macrophages. Pathway analysis of DEGs across UC cohorts demonstrated activated bacterial, inflammatory, growth, and cellular signaling. We identified a specific transcriptional signature of one hundred DEGs (UC100) that distinctly separated UC inflamed from uninflamed transcriptomes. Several UC100 DEGs, with unidentified roles in UC, were validated in primary tissue. Additionally, non-responders to anti-TNFα and anti-α4β7 therapy displayed distinct profiles of immune cells and pathways pertaining to inflammation, growth, and metabolism. We identified twenty resistant DEGs in UC non-responders to both therapies of which four had significant predictive power to treatment outcome. We demonstrated the global immune landscape and pathways in UC tissue, highlighting a unique UC signature across cohorts and a UC resistant signature with predictive performance to biologic therapy outcome.

High Ambient Temperature Aggravates Experimental Autoimmune Uveitis Symptoms

Whether ambient temperature influences immune responses leading to uveitis is unknown. We thus tested whether ambient temperature affects the symptoms of experimental autoimmune uveitis (EAU) in mice and investigated possible mechanisms. C57BL/6 mice were kept at a normal (22°C) or high temperature (30°C) housing conditions for 2 weeks and were then immunized with human interphotoreceptor retinoid-binding protein (IRBP651–670) peptide to induce EAU. Histological changes were monitored to evaluate the severity of uveitis. Frequency of Th1 cells and Th17 cells was measured by flow cytometry (FCM). The expression of IFN-γ and IL-17A mRNA was measured by real-time qPCR. The generation of neutrophil extracellular traps (NETs) was quantified by enzyme-linked immunosorbent assay (ELISA). Differential metabolites in the plasma of the mice kept in the aforementioned two ambient temperatures were measured via ultra-high-performance liquid chromatography triple quadrupole mass spectrometry quadrupole time of flight mass spectrometry (UHPLC-QQQ/MS). The differential metabolites identified were used to evaluate their effects on differentiation of Th1 and Th17 cells and generation of NETs in vitro. The results showed that EAU mice kept at high temperature experienced a more severe histopathological manifestation of uveitis than mice kept at a normal temperature. A significantly increased frequency of Th1 and Th17 cells in association with an upregulated expression of IFN-γ and IL-17A mRNA was observed in the splenic lymphocytes and retinas of EAU mice in high temperature. The expression of NETs as evidenced by myeloperoxidase (MPO) and neutrophil elastase (NE), was significantly elevated in serum and supernatants of neutrophils from EAU mice kept at high temperature compared to the normal temperature group. The metabolites in the plasma from EAU mice, fumaric acid and succinic acid, were markedly increased in the high temperature group and could induce the generation of NETs via the NADPH oxidase-dependent pathway, but did not influence the frequency of Th1 and Th17 cells. Our findings suggest that an increased ambient temperature is a risk factor for the development of uveitis. This is associated with the induction of Th1 and Th17 cells as well as the generation of NETs which could be mediated by the NADPH oxidase-dependent pathway.

Neutrophils Fuel Effective Immune Responses through Gluconeogenesis and Glycogenesis

Neutrophils can function and survive in injured and infected tissues, where oxygen and metabolic substrates are limited. Using radioactive flux assays and LC-MS tracing with U-¹³C glucose, glutamine, and pyruvate, we observe that neutrophils require the generation of intracellular glycogen stores by gluconeogenesis and glycogenesis for effective survival and bacterial killing. These metabolic adaptations are dynamic, with net increases in glycogen stores observed following LPS challenge or altitude-induced hypoxia. Neutrophils from patients with chronic obstructive pulmonary disease have reduced glycogen cycling, resulting in impaired function. Metabolic specialization of neutrophils may therefore underpin disease pathology and allow selective therapeutic targeting.

Tissue-Specific Effects of Leptin on Glucose and Lipid Metabolism

The discovery of leptin was intrinsically associated with its ability to regulate body weight. However, the effects of leptin are more far-reaching and include profound glucose-lowering and anti-lipogenic effects, independent of leptin's regulation of body weight. Regulation of glucose metabolism by leptin is mediated both centrally and via peripheral tissues and is influenced by the activation status of insulin signaling pathways. Ectopic fat accumulation is diminished by both central and peripheral leptin, an effect that is beneficial in obesity-associated disorders. The magnitude of leptin action depends upon the tissue, sex, and context being examined. Peripheral tissues that are of particular relevance include the endocrine pancreas, liver, skeletal muscle, adipose tissues, immune cells, and the cardiovascular system. As a result of its potent metabolic activity, leptin is used to control hyperglycemia in patients with lipodystrophy and is being explored as an adjunct to insulin in patients with type 1 diabetes. To fully understand the role of leptin in physiology and to maximize its therapeutic potential, the mechanisms of leptin action in these tissues needs to be further explored.

Canagliflozin alleviates LPS-induced acute lung injury by modulating alveolar macrophage polarization

BACKGROUND

Canagliflozin (CANA), a sodium-glucose cotransporter 2 inhibitor, is a novel therapeutic agent that exhibits multiple actions in type 2 diabetes. CANA can regulate intracellular glucose metabolism and exert anti-inflammatory effects in immune cells. Alveolar macrophage polarization balance is often associated with lower inflammation in acute lung injury (ALI). However, little is known about the anti-inflammatory effect of CANA on ALI.

METHODS

This study aimed to determine the effect of CANA on ALI as well as its potential ability to modulate alveolar macrophage polarization in ALI mouse models and bone marrow-derived macrophages (BMDMs).

RESULTS

The histopathological changes indicated that CANA alleviated lung injury in lipopolysaccharide-induced ALI mice models and exerted anti-inflammatory effects in the presence of lower levels of tumor necrosis factor-ɑ, interleukin-6, and interleukin-1β in bronchoalveolar lavage fluid (BALF) and serum. Moreover, flow cytometry analysis of mouse BALF cells and BMDMs demonstrated that CANA can modulate and reconstitute M1 and M2 macrophage balance, inhibiting macrophages with the M1 phenotype while promoting macrophages to shift to the M2 phenotype. Immunohistochemistry and reverse transcription polymerase chain reaction were also performed.

CONCLUSIONS

These findings indicate that CANA alleviates lung injury and exerts anti-inflammatory effects by modulating alveolar macrophage polarization balance, suggesting that CANA might act as a novel anti-inflammatory drug for treating ALI.

Glycolysis - a key player in the inflammatory response

The inflammatory response involves the activation of several cell types to fight insults caused by a plethora of agents, and to maintain the tissue homoeostasis. On the one hand, cells involved in the pro-inflammatory response, such as inflammatory M1 macrophages, Th1 and Th17 lymphocytes or activated microglia, must rapidly provide energy to fuel inflammation, which is essentially accomplished by glycolysis and high lactate production. On the other hand, regulatory T cells or M2 macrophages, which are involved in immune regulation and resolution of inflammation, preferentially use fatty acid oxidation through the TCA cycle as a main source for energy production. Here, we discuss the impact of glycolytic metabolism at the different steps of the inflammatory response. Finally, we review a wide variety of molecular mechanisms which could explain the relationship between glycolytic metabolites and the pro-inflammatory phenotype, including signalling events, epigenetic remodelling, post-transcriptional regulation and post-translational modifications. Inflammatory processes are a common feature of many age-associated diseases, such as cardiovascular and neurodegenerative disorders. The finding that immunometabolism could be a master regulator of inflammation broadens the avenue for treating inflammation-related pathologies through the manipulation of the vascular and immune cell metabolism.

Toll-like receptor-2 regulates macrophage polarization induced by excretory-secretory antigens from Schistosoma japonicum eggs and promotes liver pathology in murine schistosomiasis

Schistosomiasis is endemic to many regions of the world and affects approximately 200 million people. Conventional adaptive T cell responses are considered to be the primary contributors to the pathogenesis of Schistosoma japonicum infection, leading to liver granuloma and fibrosis. However, the functional polarization of macrophages and the associated underlying molecular mechanisms during the pathogenesis of schistosomiasis remains unknown. In the present study, we found that excretory-secretory (ES) antigens derived from S. japonicum eggs can activate macrophages, which exhibit an M2b polarization. Furthermore, ES antigen-induced M2b polarization was found to be dependent on enhanced NF-κB signaling mediated by the MyD88/MAPK pathway in a TLR2-dependent manner. In addition, the cytokine profile of the liver macrophages from wild-type-infected mice are quite distinct from those found in TLR2 knockout-infected mice by quantitative PCR analysis. More importantly, the size of granuloma and the severity of the fibrosis in the livers of TLR2^-/- mice were significantly reduced compared to that in WT mice. Our findings reveal a novel role for M2b polarization in the pathogenesis of schistosome infection.

Schistosomiasis is a global health concern that affects primarily tropical and subtropical areas. During a schistosome infection, the eggs are trapped in the host liver and products derived from eggs induce a polarized Th2 response, resulting in granuloma formation and eventually fibrosis. Thus, it is important to elucidate the mechanism of granuloma formation and fibrosis development. Here, we show that activated macrophages play a novel role in the promotion of hepatic granuloma formation and liver fibrosis in a Schistosoma japonicum-infected mouse model. In addition, M2b polarization induced by egg products was dependent on enhanced NF-κB signaling mediated by the MyD88/MAPK pathway in a TLR2-dependent manner. Our findings reveal a novel role and mechanism of M2b polarization in the liver pathogenesis in S. japonicum-infected mice.

PCK1 Downregulation Promotes TXNRD1 Expression and Hepatoma Cell Growth via the Nrf2/Keap1 Pathway

Gluconeogenesis, generates glucose from small carbohydrate substrates, and drives the metabolic flux in parallel but opposite to glycolysis. The cytoplasmic isoform of phosphoenolpyruvate carboxykinase (PCK1 or PEPCK-C), a rate-limiting enzyme in gluconeogenesis, initiates the gluconeogenesis process and is reportedly dysregulated in multiple types of cancer. Gluconeogenesis mainly occurs in the liver during fasting, and previous studies have demonstrated that PCK1 acts as a tumor suppressor in hepatocellular carcinoma (HCC); however, the role of PCK1 in cancer progression remains incompletely understood. In the current study, we found that PCK1 expression was decreased in HCC as compared to adjacent normal liver tissues, and low PCK1 expression correlated with poor patient prognosis. Furthermore, overexpression of PCK1 suppressed reactive oxygen species (ROS) production and nuclear translocation of Nrf2 in hepatoma cells. In addition, thioredoxin reductase 1 (TXNRD1), an antioxidant enzyme regulated by the Nrf2/Keap1 pathway, was downregulated upon overexpression of PCK1 in HCC cell lines. Furthermore, we verified this axis using nude mouse xenograft model. Finally, we found that auranofin, a TXNRD1 inhibitor, enhanced the sensitivity of PCK1-knockout hepatoma cells to sorafenib-induced apoptosis. Taken together, our findings suggest that PCK1 deficiency promotes hepatoma cell proliferation via the induction of oxidative stress and the activation of transcription factor Nrf2, and that targeting the TXNRD1 antioxidant pathway sensitizes PCK1-knockout hepatoma cells to sorafenib treatment in vitro.

Using Stable Isotopes in Bone Marrow Derived Macrophage to Analyze Metabolism

Using gas chromatography mass spectrometry (GC-MS) to analyze the citric acid cycle (CAC) and related intermediates (such as glutamate, glutamine, GABA, and aspartate) is an analytical approach to identify unexpected correlations between apparently related and unrelated pathways of energy metabolism. Intermediates can be as expressed as their absolute concentrations or relative ratios by using known amounts of added reference standards to the sample. GC-MS can also distinguish between heavy labeled molecules (²H- or ¹³C-labeled) and the naturally occurring most abundant molecules. Applications using tracers can also assess the turnover of specific metabolic pools under various physiological and pathological conditions as well as for pathway discovery. The following protocol is a relatively simple method that is not only sensitive for small concentrations of metabolic intermediates but can also be used in vivo or in vitro to determine the integrity of various metabolic pathways, such as flux changes within specific metabolite pools. We used this protocol to determine the role of phosphoenolpyruvate carboxykinase 1 (Pck1) gene in mouse macrophage cells to determine the percent contribution from a precursor of ¹³C labeled glucose into specific CAC metabolite pools.

Mitochondrial fidelity and metabolic agility control immune cell fate and function

Remodeling of mitochondrial metabolism plays an important role in regulating immune cell fate, proliferation, and activity. Furthermore, given their bacterial ancestry, disruption in mitochondrial fidelity leading to extravasation of their content initiates and amplifies innate immune surveillance with a myriad of physiologic and pathologic consequences. Investigations into the role of mitochondria in the immune system have come to the fore, and appreciation of mitochondrial function and quality control in immune regulation has enhanced our understanding of disease pathogenesis and identified new targets for immune modulation. This mitochondria-centered Review focuses on the role of mitochondrial metabolism and fidelity, as well as the role of the mitochondria as a structural platform, for the control of immune cell polarity, activation, and signaling. Mitochondria-linked disease and mitochondrially targeted therapeutic strategies to manage these conditions are also discussed.