Crosstalk between glucose metabolism, lactate production and immune response modulation

Lactate and Lactylation in Sepsis: A Comprehensive Review

Sepsis is a disorder of the immune response to infection or infectious factors with high morbidity and mortality in clinical settings. The lactylation of lysine residues, fueled by lactate, plays a pivotal role in its pathophysiology. In conducting a literature review on sepsis-related research, we employed a systematic approach to ensure comprehensiveness and accuracy. Initially, we conducted an extensive literature search through the PubMed database, utilizing a range of keywords including "sepsis", "lactate", "lactylation", and "epigenetic modification". The aim was to capture the most recent research related to the pathophysiological mechanisms of sepsis, metabolic disorders, and the role of lactylation. The results of the literature review revealed a close link between sepsis and metabolic dysfunction, particularly the pivotal role of lactylation in regulating immune responses and inflammatory processes. Lactate, not only an energy metabolic byproduct produced during glycolysis, affects the activity of various proteins, including those involved in immune regulation and cell signaling, through lactylation. In the context of sepsis, changes in the levels of lactylation may be closely associated with the severity and prognosis of the disease. In summary, lactylation, as an emerging type of epigenetic modification, provides a new perspective for the diagnosis and treatment of sepsis. Future research needs to further elucidate the exact mechanisms of lactylation in sepsis and explore its potential as a therapeutic target.

Gentisic acid prevents colorectal cancer metastasis via blocking GPR81-mediated DEPDC5 degradation

BACKGROUND

Metastasis driven by epithelial-mesenchymal transition (EMT) remains a significant contributor to the poor prognosis of colorectal cancer (CRC), and requires more effective interventions. GPR81 signaling has been linked to tumor metastasis, while lacks an efficient specific inhibitor.

PURPOSE

Our study aimed to investigate the effect and mechanism of Gentisic acid on colorectal cancer (CRC) metastasis.

STUDY DESIGN

A lung metastasis mouse model induced by tail vein injection and a subcutaneous graft tumor model were used. Gentisic acid (GA) was administered by an intraperitoneal injection. HCT116 was treated with lactate to establish an in vitro model.

METHODS

MC38 cells with mCherry fluorescent protein were injected into tail vein to investigate lung metastasis ability in vivo. GA was administered by intraperitoneal injection for 3 weeks. The therapeutic effect was evaluated by survival rates, histochemical analysis, RT-qPCR and live imaging. The mechanism was explored using small interfering RNA (siRNA), Western blotting, RT-qPCR and immunofluorescence.

RESULTS

GA had a therapeutic effect on CRC metastasis and improved survival rates and pathological changes in dose-dependent manner. GA emerged as an GPR81 inhibitor, effectively suppressed EMT and mTOR signaling in CRC induced by lactate both in vivo and in vitro. Mechanistically, GA halted lactate-induce degradation of DEPDC5 through impeding the activation of Chaperone-mediated autophagy (CMA).

CONCLUSION

CMA-mediated DEPDC5 degradation is crucial for lactate/GPR81-induced CRC metastasis, and GA may be a promising candidate for metastasis by inhibiting GPR81 signaling.

The characterization of protein lactylation in relation to cardiac metabolic reprogramming in neonatal mouse hearts

In mammals, the neonatal heart can regenerate upon injury within a short time after birth, while adults lose this ability. Metabolic reprogramming has been demonstrated to be critical for cardiomyocyte proliferation in the neonatal heart. Here, we reveal that cardiac metabolic reprogramming could be regulated by altering global protein lactylation. By performing 4D label-free proteomics and lysine lactylation (Kla) omics analyses in mouse hearts at postnatal days 1, 5, and 7, 2297 Kla sites from 980 proteins are identified, among which 1262 Kla sites from 409 proteins are quantified. Functional clustering analysis reveals that the proteins with altered Kla sites are mainly involved in metabolic processes. The expression and Kla levels of proteins in glycolysis show a positive correlation while a negative correlation in fatty acid oxidation. Furthermore, we verify the Kla levels of several differentially modified proteins, including ACAT1, ACADL, ACADVL, PFKM, PKM, and NPM1. Overall, our study reports a comprehensive Kla map in the neonatal mouse heart, which will help to understand the regulatory network of metabolic reprogramming and cardiac regeneration.

Trailblazing in adjuvant research: succinate's uncharted territory with neutrophils

The purpose of this study is to investigate the previously unknown connection that succinate has with neutrophils in the setting of adjuvant-mediated immunological enhancement. It has been discovered that succinates stimulate the recruitment of neutrophils in immunization sites, which in turn induces the expression of what is known as neutrophil-derived B cell-activating factor (BAFF). Further amplification of vaccine-induced antibody responses is provided via the succinate receptor 1-interferon regulatory factor 5 (SUCNR1-IRF5)-BAFF signaling pathway, which provides insights into a unique mechanism for immunological enhancement.NEW & NOTEWORTHY This study explores the role of succinate as a vaccine adjuvant, revealing its capacity to enhance neutrophil recruitment at immunization sites, which boosts B cell activation through the succinate receptor 1-interferon regulatory factor 5-B cell-activating factor (SUCNR1-IRF5-BAFF) signaling pathway. Results demonstrate succinate's potential to amplify vaccine-induced antibody responses, highlighting its significance in immunological enhancement and offering new insights into the adjuvant mechanisms of action, particularly in neutrophil-mediated immune responses.

Prognostic significance of PET/CT and its association with immuno-genomic profiling in oesophageal squamous cell carcinoma treated with immunotherapy plus chemoradiotherapy: results from a phase II study

BACKGROUND

A phase II trial (EC-CRT-001) demonstrated the promising efficacy of combining toripalimab (an anti-PD-1 antibody) with definitive chemoradiotherapy (CRT) for locally advanced oesophageal squamous cell carcinoma (ESCC). Biomarkers are key to identifying patients who may benefit from this therapeutic approach.

METHODS

Of the 42 patients with ESCC who received toripalimab combined with definitive CRT, 37 were included in this analysis. Baseline assessments included PET/CT metabolic parameters (SUVmax, SUVmean, SUVpeak, MTV, and TLG), RNA sequencing of tumour biopsies to quantify the tissue mutational burden (TMB), and multiplex immunofluorescence staining to estimate immune cell infiltration in the tumour microenvironment (TME). Frozen neoplastic samples were procured for RNA sequencing to further explore the immune-related TME.

RESULTS

Among the 37 patients, high baseline SUVmax (≥12.0; OR = 6.5, 95% CI 1.4-48.2, p = 0.032) and TLG (≥121.8; OR = 6.8, 95% CI 1.6-33.5, p = 0.012) were significantly correlated with lower complete response rates. All five PET/CT parameters were notably associated with overall survival; only SUVmax and TLG were associated with a significantly worse progression-free survival. A trend towards an inverse correlation was observed between SUVmax and TMB (R = -0.33, p = 0.062). PD-1 + CD8 + T cell infiltration was negatively correlated with MTV (R = -0.355, p = 0.034) and TLG (R = -0.385, p = 0.021). Moreover, RNA sequencing revealed that the high TLG subgroup exhibited low immune cell infiltration, indicating an immunosuppressive landscape.

CONCLUSIONS

High baseline SUVmax and TLG might predict poorer treatment response and worse survival in patients with ESCC undergoing immunotherapy combined with CRT. In addition, high PET/CT metabolic parameters, particularly TLG, were correlated with an immunosuppressive TME, which warrants further exploration.

Advances in the interaction of glycolytic reprogramming with lactylation

Lactylation is a novel post-translational modification (PTM) involving proteins that is induced by lactate accumulation. Histone lysine lactylation alters chromatin spatial configuration, influencing gene transcription and regulating the expression of associated genes. This modification plays a crucial role as an epigenetic regulatory factor in the progression of various diseases. Glycolytic reprogramming is one of the most extensively studied forms of metabolic reprogramming, recognized as a key hallmark of cancer cells. It is characterized by an increase in glycolysis and the inhibition of the tricarboxylic acid (TCA) cycle, accompanied by significant lactate production and accumulation. The two processes are closely linked by lactate, which interacts in various physiological and pathological processes. On the one hand, lactylation levels generally correlate positively with the extent of glycolytic reprogramming, being directly influenced by the lactate concentration produced during glycolytic reprogramming. On the other hand, lactylation can also regulate glycolytic pathways by affecting the transcription and structural functions of essential glycolytic enzymes. This review comprehensively outlines the mechanisms of lactylation and glycolytic reprogramming and their interactions in tumor progression, immunity, and inflammation, with the aim of elucidating the relationship between glycolytic reprogramming and lactylation.

BACH1 impairs hepatocyte regeneration after hepatectomy with repeated ischemia/reperfusion by reprogramming energy metabolism and exacerbating oxidative stress

BTB and CNC homology 1 (BACH1) regulates biological processes, including energy metabolism and oxidative stress. Insufficient liver regeneration after hepatectomy remains an issue for surgeons. The Pringle maneuver is widely used during hepatectomy and induces ischemia/reperfusion (I/R) injury in hepatocytes. A rat model of two-thirds partial hepatectomy with repeated I/R treatment was used to simulate clinical hepatectomy with Pringle maneuver. Delayed recovery of liver function after hepatectomy with the repeated Pringle maneuver in clinic and impaired liver regeneration in rat model were observed. Highly elevated lactate levels, along with reduced mitochondrial complex III and IV activities in liver tissues, indicated that the glycolytic phenotype was promoted after hepatectomy with repeated I/R. mRNA expression profile analysis of glycolysis-related genes in clinical samples and further verification experiments in rat models showed that high BACH1 expression levels correlated with the glycolytic phenotype after hepatectomy with repeated I/R. BACH1 overexpression restricted the proliferative potential of hepatocytes stimulated with HGF. High PDK1 expression and high lactate levels, together with low mitochondrial complex III and IV activities and reduced ATP concentrations, were detected in BACH1-overexpressing hepatocytes with HGF stimulation. Moreover, HO-1 expression was downregulated, and oxidative stress was exacerbated in the BACH1-overexpressing hepatocytes with HGF stimulation. Cell experiments involving repeated hypoxia/reoxygenation revealed that reactive oxygen species accumulation triggered the TGF-β1/BACH1 axis in hepatocytes. Finally, inhibiting BACH1 with the inhibitor hemin effectively restored the liver regenerative ability after hepatectomy with repeated I/R. These results provide a potential therapeutic strategy for impaired liver regeneration after repeated I/R injury.

Study on the inactivation effect and mechanism of EGCG disinfectant on Bacillus subtilis

The widespread use of chlorine-based disinfectants in drinking water treatment has led to the proliferation of chlorine-resistant bacteria and the risk of disinfection byproducts (DBPs), posing a serious threat to public health. This study aims to explore the effectiveness and potential applications of epigallocatechin gallate (EGCG) against chlorine-resistant Bacillus and its spores in water, providing new insights for the control of chlorine-resistant bacteria and improving the biological stability of distribution systems. The inactivation effects of EGCG on Bacillus subtilis (B. subtilis) and its spores were investigated using transmission electron microscopy, ATP measurement, and transcriptome sequencing analysis to determine changes in surface structure, energy metabolism, and gene expression levels, thereby elucidating the inactivation mechanism. The results demonstrate the potential application of EGCG in continuously inhibiting chlorine-resistant B. subtilis in water, effectively improving the biological stability of the distribution system. However, EGCG is not suitable for treating raw water with high spore content and is more suitable as a supplementary disinfectant for processes with strong spore removal capabilities, such as ozone, ultraviolet, or ultrafiltration. EGCG exhibits a disruptive effect on the morphological structure and energy metabolism of B. subtilis and suppresses the synthesis of substances, energy metabolism, and normal operation of the antioxidant system by inhibiting the expression of multiple genes, thereby achieving the inactivation of B. subtilis.

DAB2IP inhibits glucose uptake by modulating HIF-1α ubiquitination under hypoxia in breast cancer

Metabolic reprogramming has become increasingly important in tumor biology research. The glucose metabolic pathway is a major energy source and is often dysregulated in breast cancer. DAB2IP is widely reported to be a tumor suppressor that acts as a scaffold protein to suppress tumor malignancy in breast cancer. Interestingly, DAB2IP has also been found to be a potential regulator of glucose uptake; however, the exact mechanism remains unclear. In this study, we found that DAB2IP inhibited glucose uptake under hypoxia conditions in breast cancer cells by suppressing HIF-1α signals. Mechanically, DAB2IP interacted with the E3 ubiquitin ligase STUB1 via its PER domain, thus triggering STUB1 mediated HIF-1α ubiquitylation and degradation, and inhibit glucose metabolism and tumor progression. Deleting the PER domain abrogated the DAB2IP-related inhibitory effects on glucose uptake, intracellular ATP production, and lactic acid production in breast cancer cells. These findings elucidate the biological roles of DAB2IP in cancer-related glucose metabolism as well as a novel mechanism by which STUB1-driven HIF-1α ubiquitylated degradation is regulated in breast cancer.

Mechanic evaluation of Wu-Mei-Pill on colitis-associated colorectal cancer: An integrated transcriptomics, metabolomics, and experimental validation study

BACKGROUND

Chronic intestinal inflammatory diseases play a crucial role in the onset of colorectal cancer (CRC). Effectively impeding the progression of colitis-associated colorectal cancer (CAC) can be instrumental in hindering CRC development. Wu-Mei-Pill (WMP), a formulation comprising various herbal extracts, is clinically employed for CAC treatment, yet the underlying mechanism of WMP's efficacy in CAC remains unclear. Our study firstly demonstrated the effects and mechanisms of WMP on transcriptional and metabolic levels based on integrated transcriptomics and untargeted metabolomics and relative experimental validations.

MATERIALS AND METHODS

A CAC mouse model was established through a single injection of azoxymethane (AOM) followed by intermittent dextran sodium sulfate (DSS) intervention, with subsequent WMP administration. Initially, the therapeutic impact of WMP on the CAC model was assessed by observing survival rate, body weight change, colon length, tumor number, tumor load, and pathological changes in the colon tissue of CAC mice post-WMP intervention. Subsequently, differential genes and metabolites in the colorectal tissue of CAC mice following WMP intervention were identified through transcriptomics and non-targeted metabolomics. Finally, the influence of WMP on the peroxisome proliferator activated receptor (PPAR) pathway, Wnt pathway, and CC motif chemokine ligand 3 (CCL3)/ CC motif chemokine receptor 1 (CCR1) axis in CAC mice was verified through western blot, immunofluorescence, and ELISA based on the results of transcriptomics and non-targeted metabolomics.

RESULTS

WMP intervention enhanced survival, alleviated body weight loss, shortened colon length, tumor occurrence, and pathological changes in the colorectal tissue of CAC mice, such as glandular damage, tumourigenesis, and inflammatory cell infiltration. Transcriptomic and non-targeted metabolomic results revealed that WMP intervention up-regulated the expression of key regulatory mechanisms of fatty acid oxidation PPAR pathway-related genes (Pparg, Ppara, Cpt1a, and Acadm) and metabolites (L-carnitine and L-palmitoylcarnitine). Additionally, it down-regulated Wnt pathway-related genes (Wnt3, Axin2, Tcf7, Mmp7, Lgr5, Wnt5a, Fzd6, Wnt7b, Lef1, and Fzd10 etc.) and pro-inflammatory related genes (Il1b, Il6, Il17a, Ccl3, and Ccr1 etc.). Experimental validation demonstrated that WMP up-regulated PPAR pathway-related proteins [PPARγ, PPARα, carnitine palmitoyltransferase 1A (CPT1A), and acyl-CoA dehydrogenase medium chain (ACADM)] in the colorectal tissue of CAC mice. It also down-regulated Wnt pathway-related proteins [β-catenin, T-cell factor (TCF), lymphoid enhancer-binding factor (LEF), and matrix metallopeptidase 7 (MMP7)], inhibited the nuclear translocation of the key transcription factor β-catenin in the Wnt pathway, and suppressed epithelial-to-mesenchymal transition (EMT) activation induced by the Wnt pathway (up-regulated E-cadherin and down-regulated Vimentin). Furthermore, WMP intervention reduced pro-inflammatory factors [interleukin (IL)-6, IL-1β, and IL-17A] and decreased CCL3/CCR1 axis factors, including CCL3 protein levels and diminished F4/80+CCR1+ positive expressed cells.

CONCLUSION

WMP significantly inhibits CAC tumorigenesis by up-regulating PPARα-mediated fatty acid oxidation, inhibiting the Wnt signaling pathway-mediated EMT, and suppressing CCL3/CCR1-mediated inflammatory responses.

Sugar-sweetened beverage consumption and periodontitis among adults: A population-based cross-sectional study

AIM

Investigating the association between sugar-sweetened beverages (SSBs) and periodontitis and whether the awareness of diabetes modifies this relationship.

MATERIALS AND METHODS

Cross-sectional analysis was conducted using the National Health and Nutrition Examination Survey (NHANES III) data involving US adults aged 30-50. Periodontitis was classified according to the Centers for Disease Control and Prevention and American Academy of Periodontology (CDC-AAP), and SSB consumption as dichotomous (<5 or ≥5, <7 or ≥7 and <14 or ≥14 times/week), ordinal and continuous variables. Confounders included family income poverty ratio, education, race/ethnicity, sex, age, food energy intake, smoking and alcohol. Odds ratios (ORs) were obtained by logistic regressions using inverse probability weighting. Effect modification analysis was performed considering self-reported diabetes.

RESULTS

Among 4473 cases analysed, 198 self-reported diabetes. SSBs were associated with periodontitis when individuals consumed ≥5 (OR 1.64; 95% confidence interval [CI] = 1.30-2.06), ≥7 (OR 1.92; 95% CI = 1.50-2.46) and ≥14 (OR 2.19; 95% CI = 1.50-3.18) times/week. The combined effect of consuming SSBs (≥5 and ≥14 times/week) and self-reported diabetes had less impact than the cumulative effect.

CONCLUSIONS

SSB consumption was associated with higher odds of periodontitis, and the estimates were reduced among those with awareness of diabetes.

HIF-1α Pathway Orchestration by LCN2: A Key Player in Hypoxia-Mediated Colitis Exacerbation

In this study, we investigated the role of hypoxia in the development of chronic inflammatory bowel disease (IBD), focusing on its impact on the HIF-1α signaling pathway through the upregulation of lipocalin 2 (LCN2). Using a murine model of colitis induced by sodium dextran sulfate (DSS) under hypoxic conditions, transcriptome sequencing revealed LCN2 as a key gene involved in hypoxia-mediated exacerbation of colitis. Bioinformatics analysis highlighted the involvement of crucial pathways, including HIF-1α and glycolysis, in the inflammatory process. Immune infiltration analysis demonstrated the polarization of M1 macrophages in response to hypoxic stimulation. In vitro studies using RAW264.7 cells further elucidated the exacerbation of inflammation and its impact on M1 macrophage polarization under hypoxic conditions. LCN2 knockout cells reversed hypoxia-induced inflammatory responses, and the HIF-1α pathway activator dimethyloxaloylglycine (DMOG) confirmed LCN2's role in mediating inflammation via the HIF-1α-induced glycolysis pathway. In a DSS-induced colitis mouse model, oral administration of LCN2-silencing lentivirus and DMOG under hypoxic conditions validated the exacerbation of colitis. Evaluation of colonic tissues revealed altered macrophage polarization, increased levels of inflammatory factors, and activation of the HIF-1α and glycolysis pathways. In conclusion, our findings suggest that hypoxia exacerbates colitis by modulating the HIF-1α pathway through LCN2, influencing M1 macrophage polarization in glycolysis. This study contributes to a better understanding of the mechanisms underlying IBD, providing potential therapeutic targets for intervention.

LncRNA TUG1 mediates microglial inflammatory activation by regulating glucose metabolic reprogramming

Microglia are natural immune cells in the central nervous system, and the activation of microglia is accompanied by a reprogramming of glucose metabolism. In our study, we investigated the role of long non-coding RNA taurine-upregulated gene 1 (TUG1) in regulating microglial glucose metabolism reprogramming and activation. BV2 cells were treated with Lipopolysaccharides (LPS)/Interferon-γ (IFN-γ) to establish a microglial activation model. The glycolysis inhibitor 2-Deoxy-D-glucose (2-DG) was used as a control. The expression levels of TUG1 mRNA and proinflammatory cytokines such as Interleukin-1β (IL-1β), Interleukin -6, and Tumor Necrosis Factor-α mRNA and anti-inflammatory cytokines such as IL-4, Arginase 1(Arg1), CD206, and Ym1 were detected by RT-qPCR. TUG1 was silenced using TUG1 siRNA and knocked out using CRISPR/Cas9. The mRNA and protein expression levels of key enzymes involved in glucose metabolism, such as Hexokinase2, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Lactate dehydrogenase, Glucose 6 phosphate dehydrogenase, and Pyruvate dehydrogenase (PDH), were determined by RT-qPCR and Western blotting. The glycolytic rate of microglial cells was measured using Seahorse. Differential metabolites were determined by metabolomics, and pathway enrichment was performed using these differential metabolites. Our findings revealed that the expression of TUG1 was elevated in proinflammatory-activated microglia and positively correlated with the levels of inflammatory factors. The expression of anti-inflammatory cytokines such as IL-4, Arg1, CD206, and Ym1 were decreased when induced with LPS/IFN-γ. However, this decrease was reversed by the treatment with 2-DG. Silencing of GAPDH led to an increase in the expression of TUG1 and inflammatory factors. TUG1 knockout (TUG1KO) inhibited the expression of glycolytic key enzymes and promoted the expression of oxidative phosphorylation key enzymes, shifting the metabolic profile of activated microglia from glycolysis to oxidative phosphorylation. Additionally, TUG1KO reduced the accumulation of metabolites, facilitating the restoration of the tricarboxylic acid cycle and enhancing oxidative phosphorylation in microglia. Furthermore, the downregulation of TUG1 was found to reduce the expression of both proinflammatory and anti-inflammatory cytokines under normal conditions. Interestingly, when induced with LPS/IFN-γ, TUG1 downregulation showed a potentially beneficial effect on microglia in terms of inflammation. Downregulation of TUG1 expression inhibits glycolysis and facilitates the shift of microglial glucose metabolism from glycolysis to oxidative phosphorylation, promoting their transformation towards an anti-inflammatory phenotype and exerting anti-inflammatory effects in BV2.

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

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

Dual roles of HK3 in regulating the network between tumor cells and tumor-associated macrophages in neuroblastoma

Neuroblastoma (NB) is the most common and deadliest extracranial solid tumor in children. Targeting tumor-associated macrophages (TAMs) is a strategy for attenuating tumor-promoting states. The crosstalk between cancer cells and TAMs plays a pivotal role in mediating tumor progression in NB. The overexpression of Hexokinase-3 (HK3), a pivotal enzyme in glucose metabolism, has been associated with poor prognosis in NB patients. Furthermore, it correlates with the infiltration of M2-like macrophages within NB tumors, indicating its significant involvement in tumor progression. Therefore, HK3 not only directly regulates the malignant biological behaviors of tumor cells, such as proliferation, migration, and invasion, but also recruits and polarizes M2-like macrophages through the PI3K/AKT-CXCL14 axis in neuroblastoma. The secretion of lactate and histone lactylation alterations within tumor cells accompanies this interaction. Additionally, elevated expression of HK3 in M2-TAMs was found at the same time. Modulating HK3 within M2-TAMs alters the biological behavior of tumor cells, as demonstrated by our in vitro studies. This study highlights the pivotal role of HK3 in the progression of NB malignancy and its intricate regulatory network with M2-TAMs. It establishes HK3 as a promising dual-functional biomarker and therapeutic target in combating neuroblastoma.

LPS-induced monocarboxylate transporter-1 inhibition facilitates lactate accumulation triggering epithelial-mesenchymal transformation and pulmonary fibrosis

The epithelial-mesenchymal transformation (EMT) process of alveolar epithelial cells is recognized as involved in the development of pulmonary fibrosis. Recent evidence has shown that lipopolysaccharide (LPS)-induced aerobic glycolysis of lung tissue and elevated lactate concentration are associated with the pathogenesis of sepsis-associated pulmonary fibrosis. However, it is uncertain whether LPS promotes the development of sepsis-associated pulmonary fibrosis by promoting lactate accumulation in lung tissue, thereby initiating EMT process. We hypothesized that monocarboxylate transporter-1 (MCT1), as the main protein for lactate transport, may be crucial in the pathogenic process of sepsis-associated pulmonary fibrosis. We found that high concentrations of lactate induced EMT while moderate concentrations did not. Besides, we demonstrated that MCT1 inhibition enhanced EMT process in MLE-12 cells, while MCT1 upregulation could reverse lactate-induced EMT. LPS could promote EMT in MLE-12 cells through MCT1 inhibition and lactate accumulation, while this could be alleviated by upregulating the expression of MCT1. In addition, the overexpression of MCT1 prevented LPS-induced EMT and pulmonary fibrosis in vivo. Altogether, this study revealed that LPS could inhibit the expression of MCT1 in mouse alveolar epithelial cells and cause lactate transport disorder, which leads to lactate accumulation, and ultimately promotes the process of EMT and lung fibrosis.

Supramolecular Peptide Amphiphile Nanospheres Reprogram Tumor-associated Macrophage to Reshape the Immune Microenvironment for Enhanced Breast Cancer Immunotherapy

Tumor immunotherapy has become a research hotspot in cancer treatment, with macrophages playing a crucial role in tumor development. However, the tumor microenvironment restricts macrophage functionality, limiting their therapeutic potential. Therefore, modulating macrophage function and polarization is essential for enhancing tumor immunotherapy outcomes. Here, a supramolecular peptide amphiphile drug-delivery system (SPADS) is utilized to reprogram macrophages and reshape the tumor immune microenvironment (TIM) for immune-based therapies. The approach involved designing highly specific SPADS that selectively targets surface receptors of M2-type macrophages (M2-Mφ). These targeted peptides induced M2-Mφ repolarization into M1-type macrophages by dual inhibition of endoplasmic reticulum and oxidative stresses, resulting in improved macrophagic antitumor activity and immunoregulatory function. Additionally, TIM reshaping disrupted the immune evasion mechanisms employed by tumor cells, leading to increased infiltration, and activation of immune cells. Furthermore, the synergistic effect of macrophage reshaping and anti-PD-1 antibody (aPD-1) therapy significantly improved the immune system's ability to recognize and eliminate tumor cells, thereby enhancing tumor immunotherapy efficacy. SPADS utilization also induced lung metastasis suppression. Overall, this study demonstrates the potential of SPADS to drive macrophage reprogramming and reshape TIM, providing new insights, and directions for developing more effective immunotherapeutic approaches in cancer treatment.

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

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

Targeting tumor-intrinsic SLC16A3 to enhance anti-PD-1 efficacy via tumor immune microenvironment reprogramming

Immunotherapy, especially immune checkpoint inhibitors, has revolutionized clinical practice within the last decade. However, primary and secondary resistance to immunotherapy is common in patients with diverse types of cancer. It is well-acknowledged that tumor cells can facilitate the formation of immunosuppressive microenvironments via metabolism reprogramming, and lactic acid, the metabolite of glycolysis, is a significant contributor. SLC16A3 (also named as MCT4) is a transporter mediating lactic acid efflux. In this study, we investigated the role of glycolysis in immunotherapy resistance and aimed to improve the immunotherapy effects via Slc16a3 inhibition. Bioinformatical analysis revealed that the expression of glycolysis-related genes correlated with less CD8+ T cell infiltration and increased myeloid-derived suppressor cells (MDSC) enrichment. We found that high glycolytic activity in tumor cells adversely affected the antitumor immune responses and efficacy of immunotherapy and radiotherapy. As the transporter of lactic acid, SLC16A3 is highly expressed in glycolytic B16-F10 (RRID: CVCL_0159) cells, as well as human non-small cell lung carcinoma. We validated that Slc16a3 expression in tumor cells negatively correlated with anti-PD-1 efficiency. Overexpression of Slc16a3 in tumor cells promoted lactic acid production and efflux, and reduced tumor response to anti-PD-1 inhibitors by inhibiting CD8+ T cell function. Genetic and pharmacological inhibition of Slc16a3 dramatically reduced the glycolytic activity and lactic acid production in tumor cells, and ameliorated the immunosuppressive tumor microenvironments (TMEs), leading to boosted antitumor effects via anti-PD-1 blockade. Our study therefore demonstrates that tumor cell-intrinsic SLC16A3 may be a potential target to reverse tumor resistance to immunotherapy.

YY1 Lactylation Aggravates Autoimmune Uveitis by Enhancing Microglial Functions via Inflammatory Genes

Activated microglia in the retina are essential for the development of autoimmune uveitis. Yin-Yang 1 (YY1) is an important transcription factor that participates in multiple inflammatory and immune-mediated diseases. Here, an increased YY1 lactylation in retinal microglia within in the experimental autoimmune uveitis (EAU) group is observed. YY1 lactylation contributed to boosting microglial activation and promoting their proliferation and migration abilities. Inhibition of lactylation suppressed microglial activation and attenuated inflammation in EAU. Mechanistically, cleavage under targets & tagmentation （CUT&Tag） analysis revealed that YY1 lactylation promoted microglial activation by regulating the transcription of a set of inflammatory genes, including STAT3, CCL5, IRF1, IDO1, and SEMA4D. In addition, p300 is identified as the writer of YY1 lactylation. Inhibition of p300 decreased YY1 lactylation and suppressed microglial inflammation in vivo and in vitro. Collectively, the results showed that YY1 lactylation promoted microglial dysfunction in autoimmune uveitis by upregulating inflammatory cytokine secretion and boosting cell migration and proliferation. Therapeutic effects can be achieved by targeting the lactate/p300/YY1 lactylation/inflammatory genes axis.

Unveiling the link between lactate metabolism and rheumatoid arthritis through integration of bioinformatics and machine learning

Rheumatoid arthritis (RA) is a persistent autoimmune condition characterized by synovitis and joint damage. Recent findings suggest a potential link to abnormal lactate metabolism. This study aims to identify lactate metabolism-related genes (LMRGs) in RA and investigate their correlation with the molecular mechanisms of RA immunity. Data on the gene expression profiles of RA synovial tissue samples were acquired from the gene expression omnibus (GEO) database. The RA database was acquired by obtaining the common LMRDEGs, and selecting the gene collection through an SVM model. Conducting the functional enrichment analysis, followed by immuno-infiltration analysis and protein-protein interaction networks. The results revealed that as possible markers associated with lactate metabolism in RA, KCNN4 and SLC25A4 may be involved in regulating macrophage function in the immune response to RA, whereas GATA2 is involved in the immune mechanism of DC cells. In conclusion, this study utilized bioinformatics analysis and machine learning to identify biomarkers associated with lactate metabolism in RA and examined their relationship with immune cell infiltration. These findings offer novel perspectives on potential diagnostic and therapeutic targets for RA.

Regulation of newly identified lysine lactylation in cancer

Metabolic reprogramming is a typical hallmark of cancer. Enhanced glycolysis in tumor cells leads to the accumulation of lactate, which is traditionally considered metabolic waste. With the development of high-resolution liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), the lactate-derived, lysine lactylation(Kla), has been identified. Kla can alter the spatial configuration of chromatin and regulate the expression of corresponding genes. Metabolic reprogramming and epigenetic remodeling have been extensively linked. Accumulating studies have subsequently expanded the framework on the key roles of this protein translational modification (PTM) in tumors and have provided a new concept of cancer-specific regulation by Kla.

Microglial- neuronal crosstalk in chronic viral infection through mTOR, SPP1/OPN and inflammasome pathway signaling

HIV-infection of microglia and macrophages (MMs) induces neuronal injury and chronic release of inflammatory stimuli through direct and indirect molecular pathways. A large percentage of people with HIV-associated neurologic and psychiatric co-morbidities have high levels of circulating inflammatory molecules. Microglia, given their susceptibility to HIV infection and long-lived nature, are reservoirs for persistent infection. MMs and neurons possess the molecular machinery to detect pathogen nucleic acids and proteins to activate innate immune signals. Full activation of inflammasome assembly and expression of IL-1β requires a priming event and a second signal. Many studies have demonstrated that HIV infection alone can activate inflammasome activity. Interestingly, secreted phosphoprotein-1 (SPP1/OPN) expression is highly upregulated in the CNS of people infected with HIV and neurologic dysfunction. Interestingly, all evidence thus far suggests a protective function of SPP1 signaling through mammalian target of rapamycin (mTORC1/2) pathway function to counter HIV-neuronal injury. Moreover, HIV-infected mice knocked down for SPP1 show by neuroimaging, increased neuroinflammation compared to controls. This suggests that SPP1 uses unique regulatory mechanisms to control the level of inflammatory signaling. In this mini review, we discuss the known and yet-to-be discovered biological links between SPP1-mediated stimulation of mTOR and inflammasome activity. Additional new mechanistic insights from studies in relevant experimental models will provide a greater understanding of crosstalk between microglia and neurons in the regulation of CNS homeostasis.

Tumor metabolic crosstalk and immunotherapy

Tumor cells must resist the host's immune system while maintaining growth under harsh conditions of acidity and hypoxia, which indicates that tumors are more robust than normal tissue. Immunotherapeutic agents have little effect on solid tumors, mostly because of the tumor density and the difficulty of penetrating deeply into the tissue to achieve the theoretical therapeutic effect. Various therapeutic strategies targeting the tumor microenvironment (TME) have been developed. Immunometabolic disorders play a dominant role in treatment resistance at both the TME and host levels. Understanding immunometabolic factors and their treatment potential may be a way forward for tumor immunotherapy. Here, we summarize the metabolism of substances that affect tumor progression, the crosstalk between the TME and immunosuppression, and some potential tumor-site targets. We also summarize the progress and challenges of tumor immunotherapy.

Single cell analysis unveils the commonality and heterogeneity between nasopharyngeal and oropharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) and oropharyngeal carcinoma (OPC) are subtypes of head and neck cancer with different treatment effects due to the heterogeneity of tumor microenvironments. This study was to investigate the distinctive tumor microenvironments of NPC and OPC. Analyzing single-cell data from 10 cases of each subtype, we reveal significant differences in cellular composition, with NPC microenvironment dominated by T/NK and B cells, and OPC characterized by prevalent epithelial cells and fibroblasts. Dynamic transitions of CD8 T cells are observed in both tumor types, involving shifts from naivety to cytotoxicity, proliferation, and eventual exhaustion/exhausted states. Additionally, Tregs exhibit heightened proliferative abilities in later developmental stages, concomitant with exhaustion. These highly proliferative T cells and Tregs manifest elevated glycolysis and lactate metabolism activities. Furthermore, we explore intercellular communication between glycolytic malignant epithelial cells and these proliferative T cells. These findings offer comprehensive insights into the heterogeneity of tumor microenvironments and provide a solid foundation for future therapeutic strategies and targeted interventions.

Comparison of the gastrointestinal bacterial microbiota between dairy cows with and without mastitis

Mastitis causes significant losses in the global dairy industry, and the health of animals has been linked to their intestinal microbiota. To better understand the relationship between gastrointestinal microbiota and mastitis in dairy cows, we collected blood, rumen fluid, and fecal samples from 23 dairy cows, including 13 cows with mastitis and 10 healthy cows. Using ELISA kit and high-throughput sequencing, we found that cows with mastitis had higher concentrations of TNF-α, IL-1, and LPS than healthy cows (p < 0.05), but no significant differences in microbiota abundance or diversity (p > 0.05). Principal coordinate analysis (PCOA) revealed significant differences in rumen microbial structure between the two groups (p < 0.05), with Moryella as the signature for rumen in cows with mastitis. In contrast, fecal microbial structure showed no significant differences (p > 0.05), with Aeriscardovia, Lactococcus, and Bacillus as the signature for feces in healthy cows. Furthermore, the results showed distinct microbial interaction patterns in the rumen and feces of cows with mastitis compared to healthy cows. Additionally, we observed correlations between the microbiota in both the rumen and feces of cows and blood inflammatory indicators. Our study sheds new light on the prevention of mastitis in dairy cows by highlighting the relationship between gastrointestinal microbiota and mastitis.

Anti-inflammatory and anti-oxidative electrospun nanofiber membrane promotes diabetic wound healing via macrophage modulation

BACKGROUND

In the inflammatory milieu of diabetic chronic wounds, macrophages undergo substantial metabolic reprogramming and play a pivotal role in orchestrating immune responses. Itaconic acid, primarily synthesized by inflammatory macrophages as a byproduct in the tricarboxylic acid cycle, has recently gained increasing attention as an immunomodulator. This study aims to assess the immunomodulatory capacity of an itaconic acid derivative, 4-Octyl itaconate (OI), which was covalently conjugated to electrospun nanofibers and investigated through in vitro studies and a full-thickness wound model of diabetic mice.

RESULTS

OI was feasibly conjugated onto chitosan (CS), which was then grafted to electrospun polycaprolactone/gelatin (PG) nanofibers to obtain P/G-CS-OI membranes. The P/G-CS-OI membrane exhibited good mechanical strength, compliance, and biocompatibility. In addition, the sustained OI release endowed the nanofiber membrane with great antioxidative and anti-inflammatory activities as revealed in in vitro and in vivo studies. Specifically, the P/G-CS-OI membrane activated nuclear factor-erythroid-2-related factor 2 (NRF2) by alkylating Kelch-like ECH-associated protein 1 (KEAP1). This antioxidative response modulates macrophage polarization, leading to mitigated inflammatory responses, enhanced angiogenesis, and recovered re-epithelization, finally contributing to improved healing of mouse diabetic wounds.

CONCLUSIONS

The P/G-CS-OI nanofiber membrane shows good capacity in macrophage modulation and might be promising for diabetic chronic wound treatment.

TAB182 regulates glycolytic metabolism by controlling LDHA transcription to impact tumor radiosensitivity

Metabolic reprogramming, a hallmark of cancer, is closely associated with tumor development and progression. Changes in glycolysis play a crucial role in conferring radiation resistance to tumor cells. How radiation changes the glycolysis status of cancer cells is still unclear. Here we revealed the role of TAB182 in regulating glycolysis and lactate production in cellular response to ionizing radiation. Irradiation can significantly stimulate the production of TAB182 protein, and inhibiting TAB182 increases cellular radiosensitivity. Proteomic analysis indicated that TAB182 influences several vital biological processes, including multiple metabolic pathways. Knockdown of TAB182 results in decreased lactate production and increased pyruvate and ATP levels in cancer cells. Moreover, knocking down TAB182 reverses radiation-induced metabolic changes, such as radioresistant-related lactate production. TAB182 is necessary for activating LDHA transcription by affecting transcription factors SP1 and c-MYC; its knockdown attenuates the upregulation of LDHA by radiation, subsequently suppressing lactate production. Targeted suppression of TAB182 significantly enhances the sensitivity of murine xenograft tumors to radiotherapy. These findings advance our understanding of glycolytic metabolism regulation in response to ionizing radiation, which may offer significant implications for developing new strategies to overcome tumor radioresistance.

A lactate metabolism-related signature predicting patient prognosis and immune microenvironment in ovarian cancer

Introduction

Ovarian cancer (OV) is a highly lethal gynecological malignancy with a poor prognosis. Lactate metabolism is crucial for tumor cell survival, proliferation, and immune evasion. Our study aims to investigate the role of lactate metabolism-related genes (LMRGs) in OV and their potential as biomarkers for prognosis, immune microenvironment, and immunotherapy response.

Methods

Ovarian samples were collected from the TCGA cohort. And 12 lactate-related pathways were identified from the MsigDB database. Differentially expressed genes within these pathways were designated as LMRGs, which undergo unsupervised clustering to identify distinct clusters based on LMRGs. Subsequently, we assessed survival outcomes, immune cell infiltration levels, Hallmaker pathway activation patterns, and chemotaxis among different subtypes. After conducting additional unsupervised clustering based on differentially expressed genes (DEGs), significant differences in the expression of LMRGs between the two clusters were observed. The differentially expressed genes were subjected to subsequent functional enrichment analysis. Furthermore, we construct a model incorporating LMRGs. Subsequently, the lactate score for each tumor sample was calculated based on this model, facilitating the classification of samples into high and low groups according to their respective lactate scores. Distinct groups examined disparities in survival prognosis, copy number variation (CNV), single nucleotide variation (SNV), and immune infiltration. The lactate score served as a quantitative measure of OV's lactate metabolism pattern and an independent prognostic factor.

Results

This study investigated the potential role of LMRGs in tumor microenvironment diversity and prognosis in OV, suggesting that LMRGs play a crucial role in OV progression and the tumor microenvironment, thus serving as novel indicators for prognosis, immune microenvironment status, and response to immunotherapy.

Lactate/Hydroxycarboxylic Acid Receptor 1 in Alzheimer's Disease: Mechanisms and Therapeutic Implications-Exercise Perspective

Lactate has a novel function different from previously known functions despite its traditional association with hypoxia in skeletal muscle. It plays various direct and indirect physiological functions. It is a vital energy source within the central nervous system (CNS) and a signal transmitter regulating crucial processes, such as angiogenesis and inflammation. Activating lactate and its associated receptors elicits effects like synaptic plasticity and angiogenesis alterations. These effects can significantly influence the astrocyte-neuron lactate shuttle, potentially impacting cognitive performance. Decreased cognitive function relates to different neurodegenerative conditions, including Alzheimer's disease (AD), ischemic brain injury, and frontotemporal dementia. Therefore, lactic acid has significant potential for treating neurodegenerative disorders. Exercise is a method that induces the production of lactic acid, which is similar to the effect of lactate injections. It is a harmless and natural way to achieve comparable results. Animal experiments demonstrate that high-intensity intermittent exercise can increase vascular endothelial growth factor (VEGF) levels, thus promoting angiogenesis. In vivo, lactate receptor-hydroxycarboxylic acid receptor 1 (HCAR1) activation can occur by various stimuli, including variations in ion concentrations, cyclic adenosine monophosphate (cAMP) level elevations, and fluctuations in the availability of energy substrates. While several articles have been published on the benefits of physical activity on developing Alzheimer's disease in the CNS, could lactic acid act as a bridge? Understanding how HCAR1 responds to these signals and initiates associated pathways remains incomplete. This review comprehensively analyzes lactate-induced signaling pathways, investigating their influence on neuroinflammation, neurodegeneration, and cognitive decline. Consequently, this study describes the unique role of lactate in the progression of Alzheimer's disease.

Single-Cell RNA Sequencing Revealed That the Enrichment of TPI1+ Malignant Hepatocytes Was Linked to HCC Metastasis and Immunosuppressive Microenvironment

Background

Tumor metastasis is the leading cause of high mortality in hepatocellular carcinoma (HCC). The metastasis-related HCC microenvironment is characterized by high heterogeneity. Single-cell RNA sequencing (scRNA-seq) may aid in determining specific cell clusters involved in regulating the immune microenvironment of HCC.

Methods

The scRNA-seq data of 10 HCC samples were collected from the Gene Expression Omnibus (GEO) database GSE124395. Correlations between key gene expression and clinicopathological data were determined using public databases. HCC tissues and matched tumor-adjacent and normal tissue samples were obtained by surgical resection at Sichuan Cancer Hospital. Immune cell infiltration analysis was performed and verified by immunohistochemistry and immunofluorescent staining.

Results

Nine malignant hepatocyte clusters with different marker genes and biological functions were identified. C3_Hepatocyte-SERF2 and C6_Hepatocyte-IL13RA2 were mainly involved in the regulation of the immune microenvironment, which was also a significant pathway in regulating HCC metastasis. Key genes in malignant hepatocyte clusters that associated with HCC metastasis were further screened by LASSO regression analysis. TPI1, a key gene in C6_Hepatocyte-IL13RA2 and HCC metastasis, could participate in regulating the HCC immune microenvironment in The Cancer Genome Atlas (TCGA) and Tumor Immune Estimation Resource (TIMER) databases. Moreover, immunohistochemistry analysis demonstrated that TPI1 expression was positively correlated with HCC metastasis and poor prognosis, while negatively correlated with CD8+ T cell infiltration. The negative correlation between TPI1 expression and CD8+ T cell infiltration was further confirmed by immunofluorescence staining.

Conclusion

In summary, a cluster of TPI1+ malignant hepatocytes was associated with the suppression of CD8+ T cell infiltration and HCC metastasis, providing novel insights into potential biomarkers for immunotherapy in HCC.

Metabolic clues to aging: exploring the role of circulating metabolites in frailty, sarcopenia and vascular aging related traits and diseases

Background: Physical weakness and cardiovascular risk increase significantly with age, but the underlying biological mechanisms remain largely unknown. This study aims to reveal the causal effect of circulating metabolites on frailty, sarcopenia and vascular aging related traits and diseases through a two-sample Mendelian Randomization (MR) analysis. Methods: Exposures were 486 metabolites analyzed in a genome-wide association study (GWAS), while outcomes included frailty, sarcopenia, arterial stiffness, atherosclerosis, peripheral vascular disease (PAD) and aortic aneurysm. Primary causal estimates were calculated using the inverse-variance weighted (IVW) method. Methods including MR Egger, weighted median, Q-test, and leave-one-out analysis were used for the sensitive analysis. Results: A total of 125 suggestive causative associations between metabolites and outcomes were identified. Seven strong causal links were ultimately identified between six metabolites (kynurenine, pentadecanoate (15:0), 1-arachidonoylglycerophosphocholine, androsterone sulfate, glycine and mannose) and three diseases (sarcopenia, PAD and atherosclerosis). Besides, metabolic pathway analysis identified 13 significant metabolic pathways in 6 age-related diseases. Furthermore, the metabolite-gene interaction networks were constructed. Conclusion: Our research suggested new evidence of the relationship between identified metabolites and 6 age-related diseases, which may hold promise as valuable biomarkers.

Analysis of the Immune Response by Standardized Whole-Blood Stimulation with Metabolism Modulation

The immune system defends the body from infection and plays a vital role in a wide range of health conditions. Metabolism affects a series of physiological processes, including those linked to the function of human immune system. Cellular metabolism modulates immune cell activation and cytokine production. Understanding the relationship between metabolism and immune response has important implications for the development of immune-based therapeutics. However, the deployment of large-scale functional assays to investigate the metabolic regulation of immune response has been limited by the lack of standardized procedures. Here, we present a protocol for the analysis of immune response using standardized whole-blood stimulation with metabolism modulation. Diverse immune stimuli including pattern recognition receptor (PRR) ligands and microbial stimuli were incubated with fresh human whole blood. The metabolic inhibitors were used to modulate metabolic status in the immune cells. The variable immune responses after metabolic interventions were evaluated. We described in detail the main steps involved in the whole-blood stimulation and cytokines quantification, namely, collection and treatment of whole blood, preparation of samples and controls, cytokines detection, and stimulation with metabolic interventions. The metabolic inhibitors for anabolic pathways and catabolic pathways exert selective effects on the production of cytokines from immune cells. In addition to a robust and accurate assessment of immune response in cohort studies, the standardized whole-blood stimulation with metabolic regulation might provide new insights for modulating immunity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00114-0.

Mechanisms underlying palmitic acid-induced disruption of locomotor activity and sleep behavior in Drosophila

The globally prevalent of sleep disorders is partly attributed to unhealthy dietary habits. This study investigated the underlying mechanisms of elevated palmitic acid (PA) intake on locomotor activity and sleep behavior in Drosophila. Our results indicate that exposure to PA significantly elevated Drosophila's daytime and nighttime locomotor activity while concurrently reducing overall sleep duration. Utilizing 16S rRNA sequencing, we observed substantial alterations in the composition of the gut microbiota induced by PA, notably, characterized by a significant reduction in Lactobacillus plantarum. Furthermore, PA significantly increased the levels of inflammatory factors Upd3 and Eiger in Drosophila intestines, and downregulated the expression of Gad and Tph, as well as 5-HT1A. Conversely, Gdh and Hdc were significantly upregulated in the PA group. Supplementation with L. plantarum or lactic acid significantly ameliorated PA-induced disruptions in both locomotor activity and sleep behavior. This supplementation also suppressed the expression of intestinal inflammatory factors, thus restoring impaired neurotransmitter-mediated sleep-wake regulation. Moreover, specific knockdown of intestinal epithelial Upd3 or Eiger similarly restored disrupted neurotransmitter expression, ultimately improving PA-induced disturbances in Drosophila locomotor activity and sleep behavior. These findings provide important insights into the intricate interplay between dietary components and essential behaviors, highlighting potential avenues for addressing health challenges associated with modern dietary habits.

Oncometabolite 2-hydroxyglutarate regulates anti-tumor immunity

"Oncometabolite" 2-hydroxyglutarate (2-HG) is an aberrant metabolite found in tumor cells, exerting a pivotal influence on tumor progression. Recent studies have unveiled its impact on the proliferation, activation, and differentiation of anti-tumor T cells. Moreover, 2-HG regulates the function of innate immune components, including macrophages, dendritic cells, natural killer cells, and the complement system. Elevated levels of 2-HG hinder α-KG-dependent dioxygenases (α-KGDDs), contributing to tumorigenesis by disrupting epigenetic regulation, genome integrity, hypoxia-inducible factors (HIF) signaling, and cellular metabolism. The chiral molecular structure of 2-HG produces two enantiomers: D-2-HG and L-2-HG, each with distinct origins and biological functions. Efforts to inhibit D-2-HG and leverage the potential of L-2-HG have demonstrated efficacy in cancer immunotherapy. This review delves into the metabolism, biological functions, and impacts on the tumor immune microenvironment (TIME) of 2-HG, providing a comprehensive exploration of the intricate relationship between 2-HG and antitumor immunity. Additionally, we examine the potential clinical applications of targeted therapy for 2-HG, highlighting recent breakthroughs as well as the existing challenges.

Metabolism Serves as a Bridge Between Cardiomyocytes and Immune Cells in Cardiovascular Diseases

Metabolic disorders of cardiomyocytes play an important role in the progression of various cardiovascular diseases. Metabolic reprogramming can provide ATP to cardiomyocytes and protect them during diseases, but this transformation also leads to adverse consequences such as oxidative stress, mitochondrial dysfunction, and eventually aggravates myocardial injury. Moreover, abnormal accumulation of metabolites induced by metabolic reprogramming of cardiomyocytes alters the cardiac microenvironment and affects the metabolism of immune cells. Immunometabolism, as a research hotspot, is involved in regulating the phenotype and function of immune cells. After myocardial injury, both cardiac resident immune cells and heart-infiltrating immune cells significantly contribute to the inflammation, repair and remodeling of the heart. In addition, metabolites generated by the metabolic reprogramming of immune cells can further affect the microenvironment, thereby affecting the function of cardiomyocytes and other immune cells. Therefore, metabolic reprogramming and abnormal metabolite levels may serve as a bridge between cardiomyocytes and immune cells, leading to the development of cardiovascular diseases. Herein, we summarize the metabolic relationship between cardiomyocytes and immune cells in cardiovascular diseases, and the effect on cardiac injury, which could be therapeutic strategy for cardiovascular diseases, especially in drug research.

Lactate dehydrogenase A promotes nasopharyngeal carcinoma progression through the TAK1/NF-κB Axis

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a malignant tumor that originates in the nasopharyngeal mucosa and is common in China and Southeast Asian countries. Cancer cells reprogram glycolytic metabolism to promote their growth, survival and metastasis. Glycolysis plays an important role in NPC development, but the underlying mechanisms remain incompletely elucidated. Lactate dehydrogenase A (LDHA) is a crucial glycolytic enzyme, catalyzing the last step of glycolysis. This study aims to investigate the exact role of LDHA, which catalyzes the conversion of pyruvate into lactate, in NPC development.

METHODS AND RESULTS

The western blot and immunohistochemical (IHC) results indicated that LDHA was significantly upregulated in NPC cells and clinical samples. LDHA knockdown by shRNA significantly inhibited NPC cell proliferation and invasion. Further knockdown of LDHA dramatically weakened the tumorigenicity of NPC cells in vivo. Mechanistic studies showed that LDHA activated TGF-β-activated kinase 1 (TAK1) and subsequent nuclear factor κB (NF-κB) signaling to promote NPC cell proliferation and invasion. Exogenous lactate supplementation restored NPC cell proliferation and invasion inhibited by LDHA knockdown, and this restorative effect was reversed by NF-κB inhibitor (BAY 11-7082) or TAK1 inhibitor (5Z-7-oxozeaenol) treatment. Moreover, clinical sample analyses showed that LDHA expression was positively correlated with TAK1 Thr187 phosphorylation and poor prognosis.

CONCLUSIONS

Our results suggest that LDHA and its major metabolite lactate drive NPC progression by regulating TAK1 and its downstream NF-κB signaling, which could become a therapeutic target in NPC.

Molecular Signaling and Metabolic Responses during the Interaction between Human Keratinocytes (HaCaT) and the Dermatophyte Trichophyton rubrum

Trichophyton rubrum is the leading causative agent of dermatophytosis worldwide. Keratinocytes are the first line of defense that drives an immune response against fungal invasion. Host-specific pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs) to trigger immunological pathways. Fungal cell wall components are the primary sources of fungal PAMPs, and some pathogens increase cell wall rearrangement to evade the immune system. Glycolysis and enhanced lactate levels are critical for improving host immune responses to fungal infections. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), we evaluated the transcriptional responses of human genes involved in fungal recognition and glycolytic metabolism and fungal cell-wall-related genes in a co-culture model of human keratinocytes with T. rubrum. We observed the upregulation of several Toll-like receptors (TLRs), NOD-like receptors (NLRs), and glycolytic genes. Complementarily, we measured intra- and extracellular glucose levels and the increase in lactate production in the co-culture supernatant. We noted a distinct transcriptional regulation pattern of fungal cell-wall-related genes from fungal growth on keratin as the primary carbon source compared to co-culture with human keratinocytes. Our results showed new insights into the transcriptional adaptation of keratinocytes, particularly in regulating genes involved in sensing and metabolic processes, during the interaction with T. rubrum.

Revving the engine: PKB/AKT as a key regulator of cellular glucose metabolism

Glucose metabolism is of critical importance for cell growth and proliferation, the disorders of which have been widely implicated in cancer progression. Glucose uptake is achieved differently by normal cells and cancer cells. Even in an aerobic environment, cancer cells tend to undergo metabolism through glycolysis rather than the oxidative phosphorylation pathway. Disordered metabolic syndrome is characterized by elevated levels of metabolites that can cause changes in the tumor microenvironment, thereby promoting tumor recurrence and metastasis. The activation of glycolysis-related proteins and transcription factors is involved in the regulation of cellular glucose metabolism. Changes in glucose metabolism activity are closely related to activation of protein kinase B (PKB/AKT). This review discusses recent findings on the regulation of glucose metabolism by AKT in tumors. Furthermore, the review summarizes the potential importance of AKT in the regulation of each process throughout glucose metabolism to provide a theoretical basis for AKT as a target for cancers.

Salvianolic Acid B Alleviates Liver Injury by Regulating Lactate-Mediated Histone Lactylation in Macrophages

Salvianolic acid B (Sal B) is the primary water-soluble bioactive constituent derived from the roots of Salvia miltiorrhiza Bunge. This research was designed to reveal the potential mechanism of Sal B anti-liver injury from the perspective of macrophages. In our lipopolysaccharide-induced M1 macrophage model, Sal B showed a clear dose-dependent gradient of inhibition of the macrophage trend of the M1 type. Moreover, Sal B downregulated the expression of lactate dehydrogenase A (LDHA), while the overexpression of LDHA impaired Sal B's effect of inhibiting the trend of macrophage M1 polarization. Additionally, this study revealed that Sal B exhibited inhibitory effects on the lactylation process of histone H3 lysine 18 (H3K18la). In a ChIP-qPCR analysis, Sal B was observed to drive a reduction in H3K18la levels in the promoter region of the LDHA, NLRP3, and IL-1β genes. Furthermore, our in vivo experiments showed that Sal B has a good effect on alleviating CCl4-induced liver injury. An examination of liver tissues and the Kupffer cells isolated from those tissues proved that Sal B affects the M1 polarization of macrophages and the level of histone lactylation. Together, our data reveal that Sal B has a potential mechanism of inhibiting the histone lactylation of macrophages by downregulating the level of LDHA in the treatment of liver injury.

Macrophage fatty acid oxidation in atherosclerosis

Atherosclerosis significantly contributes to the development of cardiovascular diseases (CVD) and is characterized by lipid retention and inflammation within the artery wall. Multiple immune cell types are implicated in the pathogenesis of atherosclerosis, macrophages play a central role as the primary source of inflammatory effectors in this pathogenic process. The metabolic influences of lipids on macrophage function and fatty acid β-oxidation (FAO) have similarly drawn attention due to its relevance as an immunometabolic hub. This review discusses recent findings regarding the impact of mitochondrial-dependent FAO in the phenotype and function of macrophages, as well as transcriptional regulation of FAO within macrophages. Finally, the therapeutic strategy of macrophage FAO in atherosclerosis is highlighted.

The immunometabolic reprogramming of microglia in Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disorder (NDD). In the central nervous system (CNS), immune cells like microglia could reprogram intracellular metabolism to alter or exert cellular immune functions in response to environmental stimuli. In AD, microglia could be activated and differentiated into pro-inflammatory or anti-inflammatory phenotypes, and these differences in cellular phenotypes resulted in variance in cellular energy metabolism. Considering the enormous energy requirement of microglia for immune functions, the changes in mitochondria-centered energy metabolism and substrates of microglia are crucial for the cellular regulation of immune responses. Here we reviewed the mechanisms of microglial metabolic reprogramming by analyzing their flexible metabolic patterns and changes that occurred in their metabolism during the development of AD. Further, we summarized the role of drugs in modulating immunometabolic reprogramming to prevent neuroinflammation, which may shed light on a new research direction for AD treatment.

The role of lactate in cardiovascular diseases

Cardiovascular diseases pose a major threat worldwide. Common cardiovascular diseases include acute myocardial infarction (AMI), heart failure, atrial fibrillation (AF) and atherosclerosis. Glycolysis process often has changed during these cardiovascular diseases. Lactate, the end-product of glycolysis, has been overlooked in the past but has gradually been identified to play major biological functions in recent years. Similarly, the role of lactate in cardiovascular disease is gradually being recognized. Targeting lactate production, regulating lactate transport, and modulating circulating lactate levels may serve as potential strategies for the treatment of cardiovascular diseases in the future. The purpose of this review is to integrate relevant clinical and basic research on the role of lactate in the pathophysiological process of cardiovascular disease in recent years to clarify the important role of lactate in cardiovascular disease and to guide further studies exploring the role of lactate in cardiovascular and other diseases. Video Abstract.

Lactic acid-induced M2-like macrophages facilitate tumor cell migration and invasion via the GPNMB/CD44 axis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most prevalent form of oral and maxillofacial malignancies, characterized by a low five-year survival rate primarily caused by invasion and metastasis. The progression of OSCC is influenced by macrophage-mediated immunosuppression, which contributes to both local invasion and distant metastasis. Herein, it is of great necessity to explore the molecular mechanisms underlying the crosstalk between OSCC cells and macrophages, as it remains unclear. In the present study, we found that lactic acid orchestrated intracellular communication in the tumor microenvironment. Glycoprotein non-metastatic protein B (GPNMB), a remarkable molecule preferentially expressed by tumor-associated macrophages (TAMs), was significantly highly expressed in the OSCC tissue. The results showed that lactic acid induced macrophage polarization towards an M2-like phenotype and orchestrated GPNMB secretion from macrophages. Furthermore, paracrine GPNMB played a critical role in triggering tumor-promoting activities such as facilitating tumor cell migration, invasion, and epithelial-mesenchymal transition (EMT). In terms of molecular mechanism, GPNMB functionally interacted with the CD44 receptor, and then partially activated the PI3K/AKT/mTOR signaling cascade. Silencing of CD44 could attenuate the tumor-promoting effects of GPNMB in OSCC cells. Collectively, our findings decipher a positive feedback loop in which tumor cells metabolically interact with macrophages in the OSCC microenvironment, highlighting the potential for therapeutic targeting of the GPNMB/CD44 axis as a promising strategy for treating OSCC.

Development of a Comprehensive Gene Signature Linking Hypoxia, Glycolysis, Lactylation, and Metabolomic Insights in Gastric Cancer through the Integration of Bulk and Single-Cell RNA-Seq Data

BACKGROUND

Hypoxia and anaerobic glycolysis are cancer hallmarks and sources of the metabolite lactate. Intriguingly, lactate-induced protein lactylation is considered a novel epigenetic mechanism that predisposes cells toward a malignant state. However, the significance of comprehensive hypoxia-glycolysis-lactylation-related genes (HGLRGs) in cancer is unclear. We aimed to construct a model centered around HGLRGs for predicting survival, metabolic features, drug responsiveness, and immune response in gastric cancer.

METHODS

The integration of bulk and single-cell RNA-Seq data was achieved using data obtained from the TCGA and GEO databases to analyze HGLRG expression patterns. A HGLRG risk-score model was developed based on univariate Cox regression and a LASSO-Cox regression model and subsequently validated. Additionally, the relationships between the identified HGLRG signature and multiple metabolites, drug sensitivity and various cell clusters were explored.

RESULTS

Thirteen genes were identified as constituting the HGLRG signature. Using this signature, we established predictive models, including HGLRG risk scores and nomogram and Cox regression models. The stratification of patients into high- and low-risk groups based on HGLRG risk scores showed a better prognosis in the latter. The high-risk group displayed increased sensitivity to cytotoxic drugs and targeted inhibitors. The expression of the HGLRG BGN displayed a strong correlation with amino acids and lipid metabolites. Notably, a significant difference in immune infiltration, such as that of M1 macrophages and CD8 T cells, was correlated with the HGLRG signature. The abundant DUSP1 within the mesenchymal components was highlighted by single-cell transcriptomics.

CONCLUSION

The innovative HGLRG signature demonstrates efficacy in predicting survival and providing a practical clinical model for gastric cancer. The HGLRG signature reflects the internal metabolism, drug responsiveness, and immune microenvironment components of gastric cancer and is expected to boost patients' response to targeted therapy and immunotherapy.

Metabolic profiles in plasma of patients with herpes labialis based on GC-MS

OBJECTIVE

This study aims to compare the plasma metabolic profiles of patients with herpes labialis with healthy controls and identify the biomarkers of herpes labialis.

SUBJECTS AND METHODS

We collected 18 patients with herpes labialis and 20 healthy individuals. Plasma samples from both groups were analyzed using gas chromatography-mass spectrometry (GC-MS).

RESULTS

According to the principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), we found that metabolic profiles had changed in patients with herpes labialis compared to the controls. By further selecting the different metabolites according to the variable importance in the projection (VIP) and p valve of t-tests, we found that acetic acid, pyroglutamic acid, alanine, ethanedioic acid, cyclohexaneacetic acid, pyruvic acid, d-mannose, phosphoric acid, l-amphetamine, and citric acid were decreased in patients with herpes labialis, while sedoheptulose and ethylamine were increased. Pathway analysis showed that herpes labialis may affect the amino acid and energy metabolism.

CONCLUSIONS

Our findings may contribute to elucidating the metabolic basis of herpes labialis and provide a new perspective for further research on the "Shang-Huo" state in traditional Chinese medicine (TCM).

Exosome-mediated metabolic reprogramming: Implications in esophageal carcinoma progression and tumor microenvironment remodeling

Esophageal carcinoma is among the most fatal malignancies with increasing incidence globally. Tumor onset and progression can be driven by metabolic reprogramming, especially during esophageal carcinoma development. Exosomes, a subset of extracellular vesicles, display an average size of ∼100 nanometers, containing multifarious components (nucleic acids, proteins, lipids, etc.). An increasing number of studies have shown that exosomes are capable of transferring molecules with biological functions into recipient cells, which play crucial roles in esophageal carcinoma progression and tumor microenvironment that is a highly heterogeneous ecosystem through rewriting the metabolic processes in tumor cells and environmental stromal cells. The review introduces the reprogramming of glucose, lipid, amino acid, mitochondrial metabolism in esophageal carcinoma, and summarize current pharmaceutical agents targeting such aberrant metabolism rewiring. We also comprehensively overview the biogenesis and release of exosomes, and recent advances of exosomal cargoes and functions in esophageal carcinoma and their promising clinical application. Moreover, we discuss how exosomes trigger tumor growth, metastasis, drug resistance, and immunosuppression as well as tumor microenvironment remodeling through focusing on their capacity to transfer materials between cells or between cells and tissues and modulate metabolic reprogramming, thus providing a theoretical reference for the design potential pharmaceutical agents targeting these mechanisms. Altogether, our review attempts to fully understand the significance of exosome-based metabolic rewriting in esophageal carcinoma progression and remodeling of the tumor microenvironment, bringing novel insights into the prevention and treatment of esophageal carcinoma in the future.

Lactate-induced protein lactylation: A bridge between epigenetics and metabolic reprogramming in cancer

Lactate is not only an endpoint of glycolysis but is gradually being discovered to play the role of a universal metabolic fuel for energy via the 'lactate shuttle' moving between cells and transmitting signals. The glycolytic-dependent metabolism found in tumours and fast-growing cells has made lactate a pivotal player in energy metabolism reprogramming, which enables cells to obtain abundant energy in a short time. Moreover, lactate can provide favourable conditions for tumorigenesis by shaping the acidic tumour microenvironment, recruiting immune cells, etc. and the recently discovered lactate-induced lactylation moves even further on pro-tumorigenesis mechanisms of lactate production, circulation and utilization. As with other epigenetic modifications, lactylation can modify histone proteins to alter the spatial configuration of chromatin, affect DNA accessibility and regulate the expression of corresponding genes. What's more, the degree of lactylation is inseparable from the spatialized lactate concentration, which builds a bridge between epigenetics and metabolic reprogramming. Here, we review the important role of lactate in energy reprogramming, summarize the latest finding of lactylation in tumorigenesis and try to explore therapeutic strategies in oncotherapy that can kill two birds with one stone.

YTHDF3as a prognostic predictive biomarker of thyroid cancer and its correlation with immune infiltration

PURPOSE

Thyroid cancer (TC) is one of the most common endocrine malignancies, and its morbidity continues to rise. N6-methyladenosine (m6A) RNA methylation, an epigenetic modification, is an important regulator of gene expression in TC. Therefore, it's worth finding the characteristics and predictive value of the m6A RNA methylation regulators in thyroid cancer (TC).

METHOD

RNA-seq data of TC was downloaded from the Cancer Genome Atlas (TCGA) database to screen out the differential expressed regulators. The absolute contraction selection operator (Lasso) Cox regression was used to construct the risk model of m6A methylation regulators. The predictive value of the risk scoring model was evaluated by Kaplan Meier (K-M) analysis and receiver operating characteristic (ROC) curves. The underlying mechanism of m6A methylation regulators in TC was predicted by gene set enrichment analysis (GSEA). Further validation was performed by using immunohistochemistry (IHC) and q-PCR. The correlation between risk-related gene and immune infiltration was evaluated by Tumour Immune Estimation Resource (TIMER).

RESULTS

IGF2BP2, YTHDF1 and YTHDF3 were screened out as strong independent prognostic factors of TC. Then a risk score model was established to further screen the predictors. Finally, according to the results of overall survival (OS) and clinical characteristics of TC, YTHDF3 was screened out as a potential predictor. Meanwhile, IHC and qPCR confirmed that YTHDF3 was expressed differential in TC. The expression of YTHDF3 was positively associated with the infiltration level of CD4+ T cells and macrophages. It was strongly correlated with a variety of immune markers in TC.

CONCLUSION

We confirmed that YTHDF3 can be used as a potential prognostic biomarker of TC. It not only plays a decisive role in the initiation and development of TC, but also provides a new perspective for understanding the modification of m6A RNA in TC.

Structural characterization and adjuvant action of Paulownia tomentosa flower polysaccharide on the immune responses to classical swine fever vaccine in mice

Paulownia tomentosa flower polysaccharide (PTFP) from dried cultured P. tomentosa flowers, is widely known for its immunomodulatory activities. Here, PTFP was extracted from Paulownia tomentosa flower using hot water extraction, followed by ethanol precipitation methods. Structural characterization of PTFP was revealed by scanning electron microscope, high-performance anion-exchange chromatography, gel chromatography, ultraviolet and infrared spectral. Meanwhile, adjuvant action of PTFT on the immune responses to classical swine fever vaccine in mice was evaluated to further proclaim the immune regulatory effect of PTFP. The results showed that PTFP was a type of heteropolysaccharide with a dense, rough surface and high molecular weight (667.02 kDa), mainly composed of glucose (30.93%), rhamnose (29.99%), galactose (15.66%), arabinose (6.95%), mannose (5.52%), and xylose (4.80%). The results of gel chromatography suggested that the molecular configuration of PTFP may be a spherical structure. The infrared spectrum results confirmed that the functional groups and chemical bond of PTFP contained -OH, O-H, C-H, C=O, C-O, etc. Moreover, PTFP exhibited obvious immune enhancement effect by improving concanavalin A (ConA), lipopolysaccharide (LPS), and CSFV E2-stimulated splenocyte growth and natural killer cell activity in CSFV-immunized mice. Similarly, the titers of CSFV E2-specific IgG, IgG1, IgG2a, and IgG2b antibodies and IFN-γ and IL-10 levels in CSFV-immunized mice were distinctly increased by PTFP treatment. Overall, PTFP was a macromolecular heteropolysaccharide primarily containing glucose and rhamnose, and possessed the auxiliary effect of immune enhancement on the immune responses to classical swine fever vaccine.