Expression Of Monocarboxylate Transporter Research Articles

Altered Expression of Thyroid- and Calcium Ion Channels-Related Genes in Rat Testes by Short-Term Exposure to Commercial Herbicides Paraquat or 2,4-D.

Exposure to pesticides such as paraquat and 2,4-dichlorophenoxyacetic acid (2,4-D) has been linked to harmful health effects, including alterations in male reproduction. Both herbicides are widely used in developing countries and have been associated with reproductive alterations, such as disruption of spermatogenesis and steroidogenesis. The thyroid axis and Ca2+-permeable ion channels play a key role in these processes, and their disruption can lead to reproductive issues and even infertility. This study evaluated the short-term effects of exposure to commercial herbicides based on paraquat and 2,4-D on gene expression in rat testes. At the molecular level, exposure to paraquat increased the expression of the thyroid hormone transporters monocarboxylate transporter 8 (Mct8) and organic anion-transporting polypeptide 1C1 (Oatp1c1) and the thyroid receptor alpha (TRα), suggesting a possible endocrine disruption. However, it did not alter the expression of the sperm-associated cation channels (CatSper1-2) or vanilloid receptor-related osmotically activated channel (Trpv4) related to sperm motility. In contrast, exposure to 2,4-D reduced the expression of the Mct10 transporter, Dio2 deiodinase, and CatSper1, which could affect both the availability of T3 in testicular cells and sperm quality, consistent with previous studies. However, 2,4-D did not affect the expression of CatSper2 or Trpv4. Deregulation of gene expression could explain the alterations in male reproductive processes reported by exposure to paraquat and 2,4-D. These thyroid hormone-related genes can serve as molecular biomarkers to assess endocrine disruption due to exposure to these herbicides, aiding in evaluating the health risks of pesticides.

Comparison of chemical composition between imitation wild and transplanted Astragali Radix and their therapeutic effects on heart failure

Ethnopharmacological relevanceAstragali Radix (AR) is a traditional Chinese herbal medicine, which has been widely used on treating chronic heart failure (CHF) in clinical practice. Two main types of AR in the market are the imitation wild AR (5YAR) and transplanted AR (2YAR). It remains unclear whether there are variations in the anti-heart failure effects of AR with different growth years. Further research is required to explore the material composition and mechanisms of AR in combating heart failure. Aim of the studyThe aim of the study was to compare the main chemical composition content and the protective effects of 2YAR and 5YAR on heart failure. Materials and methodsEthanol extracts of 2YAR and 5YAR were prepared, and chemical composition analysis was conducted. C57BL/6 mice were subcutaneously injected with ISO to induce heart failure (HF) and were administrated with a corresponding dose of the extracts of 2YAR and 5YAR by gavage for 28 days. Cardiac function was evaluated using echocardiography. The serum levels of enzymes related to myocardial injury, oxidative stress, and inflammation were detected. The left ventricle was excised for hematoxylin-eosin, Masson, Sirius Red, wheat germ agglutinin, and TUNEL staining. Electron microscopy examination of mitochondrial structure in myocardial cells. Protein expression of monocarboxylate transporter 4 (MCT4), Peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), phosphorylated AMP-activated protein kinase (p-AMPK), phosphorylated serine/threonine protein kinase (p-AKT), and phosphorylated insulin receptor substrates 1 (p-IRS-1) were detected by immunohistochemistry and Western blot. ResultsThe content of saponins and flavonoids in 5YAR was higher than that in the 2YAR. However, the content of polysaccharides in 5YAR is lower than in 2YAR. The treatment of 2YAR and 5YAR daily for 28 days prevented ISO-induced myocardial damage, including the decrease in serum cardiac enzymes and cardiomyocyte apoptotic index, and improvement in heart function and mitochondrial structure. Additionally, 2YAR and 5YAR reduced serum inflammatory factors and myocardial fibrosis levels. Treatment with 2YAR and 5YAR also decreased MCT4 expression and enhanced PGC-1α, p-AKT, p-AMPK, and p-IRS-1 expression in heart tissues. ConclusionsThe 5YAR was better than 2YAR in anti-heart failure, which may be related to the increase in saponins and flavonoids content. AR exerts anti-heart failure effect by improving mitochondrial function and ameliorating cardiac insulin resistance through activation of the AMPK/PGC1α and IRS/AKT pathways.

MCT4 is an independent prognostic factor and affects immune cell infiltration in patients with colorectal liver oligometastases.

Monocarboxylate transporter 4 (MCT4) is a novel biomarker related to the level of immune cell infiltration, but its impact on tumor immune microenvironment (TIME) of colorectal liver oligometastases (CLO) remains unclear. The aim of this study was to assess MCT4 expression in primary tumor and liver oligometastases, investigate its impact on immune cell infiltration and its prognostic value for CLO patients undergoing liver resection. We retrospectively selected 135 CLO patients who underwent curative liver resection between June 1999 and December 2016, and samples included 74 primary tumor tissues and 122 liver metastases. Immunohistochemistry (IHC) was performed to detect MCT4 expression in paraffin-embedded specimens and tyramine signal amplification (TSA) was used to detect the density of tumor-infiltrating lymphocytes, including CD3 + , CD8 + and Foxp3 + . Recurrence-free survival (RFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and log-rank test, and independent prognostic factors were identified with Cox regression modeling. Survival analysis indicated that CLO patients with low MCT4 expression had better 3-year RFS and 3-year OS rates than those with high MCT4 expression. Multivariate analysis indicated that high MCT4 expression was independently associated with poor RFS and OS. High MCT4 expression was associated with a lower number of intratumoral CD3 + /CD8 + T cells and was associated with higher Foxp3 + T cells infiltration. Patients with low MCT4 expression and high levels of differential immune infiltration had longer survival. MCT4 overexpression was associated with an unfavorable prognosis in patients with CLO and MCT4 expression level had an impact on intratumoral immune infiltration degree. A novel parameter that combined MCT4 expression level and differential immune infiltration level was constructed to stratify patients with CLO into different risk groups.

The Role of Astrocyte-Neuron Lactate Shuttle in Neuropathic Orofacial Pain.

Inhibition of astrocytic energy metabolism alleviates neuropathic pain. To explore whether astrocyte-neuron lactate shuttle (ANLS) played any role in neuropathic orofacial pain. Rats with partial transection of the right infraorbital nerve (p-IONX) or sham operation were intrathecally injected with acetazolamide (a carbonic anhydrase inhibitor), bithionol (a soluble adenylyl cyclase inhibitor), α-cyano-4-hydroxycinnamic acid [α-CHCA, a monocarboxylate transporter (MCT) inhibitor] or vehicle once a day from postoperative day 1-14. The facial mechanical thresholds were tested on preoperative day 1 and 2 and postoperative days 1, 3, 5, 7, 10 and 14, expression of glucose transporters (GLUTs) and MCTs in the trigeminal subnucleus caudalis (Vc) were examined on the postoperative day 3 and neuronal activities in the Vc were examined in the p-IONX rats on postoperative days 3-5. Compared with the sham group, the mechanical thresholds in the p-IONX group were significantly reduced at postoperative days 1-7, and the number of astrocytes expressing GLUT1 and MCT1/4, and neurons expressing MCT2 was significantly increased on postoperative day 3. In the p-IONX groups, neurons in the Vc were sensitised, and acetazolamide, bithionol and α-CHCA reversed the central sensitisation, significantly increased the mechanical thresholds at postoperative days 1-7 and decreased the number of astrocytes expressing GLUT1 and MCT1/4, and neurons expressing MCT2 at postoperative day 3 compared with those in the vehicle-treated rats. Inhibition of ANLS alleviates p-IONX-related neuronal, behavioural and immunohistochemical changes, which suggests that ANLS plays an important role in trigeminal neuropathic pain.

Effect of butyrate sources in a high-concentrate diet on rumen structure and function in growing rams

Dietary butyrate is considered to have mostly positive impacts on the ruminal epithelium. However, its supplementation in a high-concentrate diet may not be justified as excessive ruminal butyrate may negatively affect the rumen. Furthermore, butyrate impact on the rumen may depend on its source. Thirty-two Świniarka growing rams (30.6 ± 2.5 kg; 11–14 months of age) were used to investigate the effect of a high-concentrate diet and sodium butyrate (SB) or tributyrin (TB) supplementation in a high-concentrate diet on the rumen structure and selected functions. The rams were allocated to four treatments and fed diets with: (1) low concentrate inclusion (22.5% of diet DM; L); (2) high concentrate inclusion (60% of diet DM; H); (3) H with SB (3.2% of diet DM; H+SB); and (4) H with TB (2.93% of diet DM; H+TB). The preplanned contrasts were used for treatment comparisons (L vs H treatments (H, H+SB, and H+TB), H vs H+SB, and H vs H+TB). The BW, BW gain and DM intake did not differ between treatments. In the atrium ruminis, epithelium thickness did not differ between the L and H treatments (P = 0.46), tended to be higher for H+SB than for H (P = 0.09) but did not differ between H+TB and H (P = 0.61). The expression of downregulated in adenoma was higher for L than for H treatments (P = 0.03) but was not affected by SB or TB supplementation (P ≥ 0.26). In the ventral rumen, the mucosa surface and epithelium thickness were lower for L than for H treatments (P < 0.01), were or tended to be higher for H+SB than for H (P ≤ 0.06) but did not differ between H+TB and H (P ≥ 0.26). The expression of monocarboxylate transporter 1 was lower for L than for H treatments (P = 0.02) but was not affected by SB or TB supplementation (P ≥ 0.28). The expression of putative anion transporter-1 and downregulated in adenoma did not differ between the L and H treatments (P ≥ 0.76); however, expression of the former tended to be higher and the latter tended to be lower for H+SB than for H (P ≤ 0.09), whereas no differences were observed between H+TB and H (P ≥ 0.14). In summary, SB supplementation, but not TB supplementation, in a high-concentrate diet stimulated ruminal epithelium growth and affected short-chain fatty acid transporters expression in the ruminal epithelium.

Astrocytic metabolic control of orexinergic activity in the lateral hypothalamus regulates sleep and wake architecture

Neuronal activity undergoes significant changes during vigilance states, accompanied by an accommodation of energy demands. While the astrocyte-neuron lactate shuttle has shown that lactate is the primary energy substrate for sustaining neuronal activity in multiple brain regions, its role in regulating sleep/wake architecture is not fully understood. Here we investigated the involvement of astrocytic lactate supply in maintaining consolidated wakefulness by downregulating, in a cell-specific manner, the expression of monocarboxylate transporters (MCTs) in the lateral hypothalamus of transgenic mice. Our results demonstrate that reduced expression of MCT4 in astrocytes disrupts lactate supply to wake-promoting orexin neurons, impairing wakefulness stability. Additionally, we show that MCT2-mediated lactate uptake is necessary for maintaining tonic firing of orexin neurons and stabilizing wakefulness. Our findings provide both in vivo and in vitro evidence supporting the role of astrocyte-to-orexinergic neuron lactate shuttle in regulating proper sleep/wake stability.

Amyloid-β oligomer-induced neurotoxicity by exosomal interactions between neuron and microglia

A hallmark of Alzheimer's disease (AD) is amyloid-β (Aβ) plaque deposition in the brain, causing deficits in cognitive function. Amyloid-beta oligomers (AβOs), the soluble precursor peptides producing Aβ plaques, also produce neurotoxicity and microgliosis together with glycolytic reprogramming. Recently, monocarboxylate transporter 1 (MCT1), a key glycolysis regulator, and its ancillary protein, CD147, are found to play an important role in the secretion of exosomes, 30–200 nm vesicles in size, which are considered as toxic molecule carriers in AD. However, the effect of low-concentration AβOs (1 nM) on microglia MCT1 and CD147 expression as well as 1 nM AβOs-treated microglia-derived exosomes on neuronal toxicity remain largely elusive. In this study, 1 nM AβOs induce significant axonopathy and microgliosis. Furthermore, 1 nM AβOs-treated neurons- or microglia-derived exosomes produce axonopathy through their autologous or heterologous uptake by neurons, supporting the role of exosomes as neurotoxicity mediators in AD. Interestingly, MCT1 and CD147 are enhanced in microglia by treatment with 1 nM AβOs or exosomes from 1 nM AβOs-treated- microglia or neurons, suggesting the implication of AβOs-induced enhanced MCT1 and CD147 in microglia with AD neuropathogenesis, which is consistent with the in-silico analysis of the single cell RNA sequencing data from microglia in mouse models of AD and AD patients.

Histology-Based Radiomics for [18F]FDG PET Identifies Tissue Heterogeneity in Pancreatic Cancer.

Radiomics features can reveal hidden patterns in a tumor but usually lack an underlying biologic rationale. In this work, we aimed to investigate whether there is a correlation between radiomics features extracted from [18F]FDG PET images and histologic expression patterns of a glycolytic marker, monocarboxylate transporter-4 (MCT4), in pancreatic cancer. Methods: A cohort of pancreatic ductal adenocarcinoma patients (n = 29) for whom both tumor cross sections and [18F]FDG PET/CT scans were available was used to develop an [18F]FDG PET radiomics signature. By using immunohistochemistry for MCT4, we computed density maps of MCT4 expression and extracted pathomics features. Cluster analysis identified 2 subgroups with distinct MCT4 expression patterns. From corresponding [18F]FDG PET scans, radiomics features that associate with the predefined MCT4 subgroups were identified. Results: Complex heat map visualization showed that the MCT4-high/heterogeneous subgroup was correlating with a higher MCT4 expression level and local variation. This pattern linked to a specific [18F]FDG PET signature, characterized by a higher SUVmean and SUVmax and second-order radiomics features, correlating with local variation. This MCT4-based [18F]FDG PET signature of 7 radiomics features demonstrated prognostic value in an independent cohort of pancreatic cancer patients (n = 71) and identified patients with worse survival. Conclusion: Our cross-modal pipeline allows the development of PET scan signatures based on immunohistochemical analysis of markers of a particular biologic feature, here demonstrated on pancreatic cancer using intratumoral MCT4 expression levels to select [18F]FDG PET radiomics features. This study demonstrated the potential of radiomics scores to noninvasively capture intratumoral marker heterogeneity and identify a subset of pancreatic ductal adenocarcinoma patients with a poor prognosis.

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.

Expression of the monocarboxylate transporter MCT1 is required for virus-specific mouse CD8+ T cell memory development

Lactate-proton symporter monocarboxylate transporter 1 (MCT1) facilitates lactic acid export from T cells. Here, we report that MCT1 is mandatory for the development of virus-specific CD8+ T cell memory. MCT1-deficient T cells were exposed to acute pneumovirus (pneumonia virus of mice, PVM) or persistent γ-herpesvirus (Murid herpesvirus 4, MuHV-4) infection. MCT1 was required for the expansion of virus-specific CD8+ T cells and the control of virus replication in the acute phase of infection. This situation prevented the subsequent development of virus-specific T cell memory, a necessary step in containing virus reactivation during γ-herpesvirus latency. Instead, persistent active infection drove virus-specific CD8+ T cells toward functional exhaustion, a phenotype typically seen in chronic viral infections. Mechanistically, MCT1 deficiency sequentially impaired lactic acid efflux from activated CD8+ T cells, caused an intracellular acidification inhibiting glycolysis, disrupted nucleotide synthesis in the upstream pentose phosphate pathway, and halted cell proliferation which, ultimately, promoted functional CD8+ T cell exhaustion instead of memory development. Taken together, our data demonstrate that MCT1 expression is mandatory for inducing T cell memory and controlling viral infection by CD8+ T cells.

Severely polarized extracellular acidity around tumour cells.

Extracellular pH impacts many molecular, cellular and physiological processes, and hence is tightly regulated. Yet, in tumours, dysregulated cancer cell metabolism and poor vascular perfusion cause the tumour microenvironment to become acidic. Here by leveraging fluorescent pH nanoprobes with a transistor-like activation profile at a pH of 5.3, we show that, in cancer cells, hydronium ions are excreted into a small extracellular region. Such severely polarized acidity (pH <5.3) is primarily caused by the directional co-export of protons and lactate, as we show for a diverse panel of cancer cell types via the genetic knockout or inhibition of monocarboxylate transporters, and also via nanoprobe activation in multiple tumour models in mice. We also observed that such spot acidification in ex vivo stained snap-frozen human squamous cell carcinoma tissue correlated with the expression of monocarboxylate transporters and with the exclusion of cytotoxic T cells. Severely spatially polarized tumour acidity could be leveraged for cancer diagnosis and therapy.

Pyruvate maintains and enhances the pro-inflammatory response of microglia caused by glucose deficiency in early stroke.

Pro-inflammatory microglia mainly rely on glycolysis to maintain cytokine production during ischemia, accompanied by an increase in inducible nitric oxide synthase (iNOS) and monocarboxylate transporter 1 (MCT1). The role of energy metabolism in the pro-inflammatory response of microglia is currently unclear. In this study, we tested the response of microglia in mice after cerebral ischemia and simulated an energy environment in vitro using low glucose culture medium. The research results indicate that the expression levels of iNOS and arginase 1 (ARG1) increase in the ischemic mouse brain, but the upregulation of MCT1 expression is mainly present in iNOS positive microglia. In microglia exposed to low glucose conditions, iNOS and MCT1 levels increased, while ARG1 levels decreased. Under the same conditions, knocking down MCT1 in microglia leads to a decrease in iNOS levels, while overexpression of MCT1 leads to the opposite result. The use of NF-κB inhibitors reduced the expression levels of iNOS and MCT1 in microglia. In summary, our data indicate that pyruvate maintains and enhances the NF-κB regulated pro-inflammatory response of microglia induced by low glucose.

Lactate coordinated with exercise promoted the browning of inguinal white adipose tissue.

Lactate, an important exercise metabolite, induces white adipose tissue browning by upregulated uncoupling protein 1 (UCP1) expression. However, the function of lactate during browning of inguinal white adipose tissue (iWAT) caused by exercise is unclear. Here, we considered lactate as an exercise supplement and investigated the effects of chronic pre-exercise lactate administration on energy metabolism and adipose tissue browning. C57B/L6 male mice (5 weeks of age) were divided into six groups. We evaluated the changes in blood lactate levels in each group of mice after the intervention. Energy expenditure was measured after the intervention immediately by indirect calorimetry. The marker protein levels and gene expressions were determined by western-blot and quantitative real-time PCR. HIIT significantly decreased adipose tissue weight while increased energy expenditure and the expression of UCP1 in iWAT; however, these regulations were inhibited in the DCA+HIIT group. Compared with the MICT and LAC groups, long-term lactate injection before MICT led to lower WAT weight to body weight ratios and higher energy expenditure in mice. Furthermore, the marker genes of browning in iWAT, such as Ucp1 and Pparγ, were significantly increased in the LAC+MICT group than in the other groups, and the expression of monocarboxylate transporter-1 (Mct1) mRNA was also significantly increased. Lactate was involved in exercise-mediated browning of iWAT, and its mechanism might be the increased of lactate transport through MCT1 or PPARγ upregulation induced by exercise. These findings suggest exogenous lactate may be a new exercise supplement to regulate metabolism.

MCT1-governed pyruvate metabolism is essential for antibody class-switch recombination through H3K27 acetylation

Monocarboxylate transporter 1 (MCT1) exhibits essential roles in cellular metabolism and energy supply. Although MCT1 is highly expressed in activated B cells, it is not clear how MCT1-governed monocarboxylates transportation is functionally coupled to antibody production during the glucose metabolism. Here, we report that B cell-lineage deficiency of MCT1 significantly influences the class-switch recombination (CSR), rendering impaired IgG antibody responses in Mct1f/fMb1Cre mice after immunization. Metabolic flux reveals that glucose metabolism is significantly reprogrammed from glycolysis to oxidative phosphorylation in Mct1-deficient B cells upon activation. Consistently, activation-induced cytidine deaminase (AID), is severely suppressed in Mct1-deficient B cells due to the decreased level of pyruvate metabolite. Mechanistically, MCT1 is required to maintain the optimal concentration of pyruvate to secure the sufficient acetylation of H3K27 for the elevated transcription of AID in activated B cells. Clinically, we found that MCT1 expression levels are significantly upregulated in systemic lupus erythematosus patients, and Mct1 deficiency can alleviate the symptoms of bm12-induced murine lupus model. Collectively, these results demonstrate that MCT1-mediated pyruvate metabolism is required for IgG antibody CSR through an epigenetic dependent AID transcription, revealing MCT1 as a potential target for vaccine development and SLE disease treatment.

MCT1-mediated endothelial cell lactate shuttle as a target for promoting axon regeneration after spinal cord injury.

Rationale: Spinal cord injury (SCI)-induced vascular damage causes ischemia and hypoxia at the injury site, which, in turn, leads to profound metabolic disruptions. The effects of these metabolic alterations on neural tissue remodeling and functional recovery have yet to be elucidated. The current study aimed to investigate the consequences of the SCI-induced hypoxic environment at the epicenter of the injury. Methods: This study employed metabolomics to assess changes in energy metabolism after SCI. The use of a lactate sensor identified lactate shuttle between endothelial cells (ECs) and neurons. Reanalysis of single-cell RNA sequencing data demonstrated reduced MCT1 expression in ECs after SCI. Additionally, an adeno-associated virus (AAV) overexpressing MCT1 was utilized to elucidate its role in endothelial-neuronal interactions, tissue repair, and functional recovery. Results: The findings revealed markedly decreased monocarboxylate transporter 1 (MCT1) expression that facilitates lactate delivery to neurons to support their energy metabolism in ECs post-SCI. This decreased expression of MCT1 disrupts lactate transport to neurons, resulting in a metabolic imbalance that impedes axonal regeneration. Strikingly, our results suggested that administering adeno-associated virus specifically to ECs to restore MCT1 expression enhances axonal regeneration and improves functional recovery in SCI mice. These findings indicate a novel link between lactate shuttling from endothelial cells to neurons following SCI and subsequent neural functional recovery. Conclusion: In summary, the current study highlights a novel metabolic pathway for therapeutic interventions in the treatment of SCI. Additionally, our findings indicate the potential benefits of targeting lactate transport mechanisms in recovery from SCI.

BUTYRATE-PRODUCING BACTERIA INCREASE GUT MICROBIOTA DIVERSITY TO DELAY INTESTINAL INFLAMMAGING

Abstract Intestinal flora dysbiosis is a key link in intestinal inflammaging, and the diversity of gut microbiota plays an important role in maintaining the entire intestinal microecology. Our previous study found that butyrate-producing bacteria reversed aging-induced intestinal inflammation and promoted the expression of intestinal anti-inflammatory factors in 24-month-old mice, but the mechanism was unclear. We found that butyrate-producing bacteria promote the expression of short-chain fatty acid (SCFA) receptors in the intestine. Monocarboxylate transporter 1 (MCT-1) has anti-inflammatory effects on intestinal inflammation. We speculate that butyrate-producing bacteria upregulate MCT-1 expression through the activation of SCFA receptors, thereby promoting gut stability and bacterial diversity. In further experiments, we established inflammation models using cell lines, colon organoids, mouse colonic epithelial cells, and aged mice (24 months old) given different concentrations of LPS and DSS, and then added butyrate-producing bacteria to verify that MCT-1 is involved in the resistance of butyrate-producing bacteria to intestinal inflammation. We found that bacteria up-regulated the expression of MCT-1 by activating SCFA receptors. From the results of 16s rRNA sequencing, it can be seen that the intestinal stability and bacterial diversity of aged mice were improved after the administration of butyrate-producing bacteria. The research results will provide an experimental basis for treating intestinal inflammaging by restoring intestinal stability and diversity of gut microbiota and will help to explore the clinical value of butyrate-producing bacteria, which has important translational significance.

Visualizing cancer-originating acetate uptake through monocarboxylate transporter 1 in reactive astrocytes in the glioblastoma tumor microenvironment.

Reactive astrogliosis is a hallmark of various brain pathologies, including neurodegenerative diseases and glioblastomas. However, the specific intermediate metabolites contributing to reactive astrogliosis remain unknown. This study investigated how glioblastomas induce reactive astrogliosis in the neighboring microenvironment and explore 11C-acetate PET as an imaging technique for detecting reactive astrogliosis. Through in vitro, mouse models, and human tissue experiments, we examined the association between elevated 11C-acetate uptake and reactive astrogliosis in gliomas. We explored acetate from glioblastoma cells, which triggers reactive astrogliosis in neighboring astrocytes by upregulating MAO-B and monocarboxylate transporter 1 (MCT1) expression. We evaluated the presence of cancer stem cells in the reactive astrogliosis region of glioblastomas and assessed the correlation between the volume of 11C-acetate uptake beyond MRI and prognosis. Elevated 11C-acetate uptake is associated with reactive astrogliosis and astrocytic MCT1 in the periphery of glioblastomas in human tissues and mouse models. Glioblastoma cells exhibit increased acetate production as a result of glucose metabolism, with subsequent secretion of acetate. Acetate derived from glioblastoma cells induces reactive astrogliosis in neighboring astrocytes by increasing the expression of MAO-B and MCT1. We found cancer stem cells within the reactive astrogliosis at the tumor periphery. Consequently, a larger volume of 11C-acetate uptake beyond contrast-enhanced MRI was associated with a worse prognosis. Our results highlight the role of acetate derived from glioblastoma cells in inducing reactive astrogliosis and underscore the potential value of 11C-acetate PET as an imaging technique for detecting reactive astrogliosis, offering important implications for the diagnosis and treatment of glioblastomas.

Metabolic Syndrome‐Associated Oligodendrocyte Dysfunction and Cognitive Impairment

AbstractBackgroundOne in nine people aged 65 and older in the United States suffer from cognitive decline, including dementias such as Alzheimer’s disease (AD) and AD‐related Dementias (ADRD). A major risk factor for cognitive impairment is midlife metabolic syndrome (MetS). MetS‐associated cognitive impairment progresses in a non‐cell autonomous manner and implicates a breakdown in metabolic support. This breakdown in metabolic support is likely due to disruption of metabolic crosstalk between neurons and glia, especially oligodendrocytes. Our aim was therefore to elucidate midlife MetS effects on oligodendrocytes and subsequent impact on oligodendrocyte metabolism and cognition.MethodTo accomplish this aim, middle‐aged mice (12‐month old) were fed either standard diet (SD, 10% fat) or high‐fat diet (HFD, 60% fat) for 13 weeks, followed by full assessment of metabolic parameters and cognitive function. Oligodendrocytes were then isolated for single cell RNA‐sequencing (scRNA‐seq), and protein expression of monocarboxylate transporters (MCTs).ResultWe observed that, as expected, HFD mice gained more weight and had higher blood glucose and fat mass versus SD controls. Middle‐aged HFD mice also performed worse in puzzle box and social recognition tests, reflecting impaired executive function and impaired short‐ and long‐term memory responses. scRNA‐seq analysis identified multiple oligodendrocyte clusters. One cluster of interest contained genes involved in cognition (Fam171a2, Nrsn1, Dlgap4) and metabolism (Ldhb, Slc25a5, Cox7c, Cox17), which were differentially expressed in HFD versus SD mice. This was coupled with downregulated MCT1 protein expression in HFD mouse oligodendrocytes versus oligodendrocytes from their SD counterparts. In vitro, human oligodendrocytes treated with palmitate to mimic MetS developed insulin resistance and had downregulated MCT1 protein expression.ConclusionCollectively, these results suggest that midlife MetS impairs oligodendrocyte metabolic function, suggesting a novel mechanism underlying MetS‐associated cognitive impairment.

Metal organic frameworks based intelligent nanoadjuvants for boosting tumor immunotherapy through enhanced ICD and lactic acid regulation

Immunotherapy has been considered as a potent antitumor modality while its efficacy is frequently hampered by the insufficient immunogenicity and immunosuppressive tumor microenvironment (TME) with overexpressed lactic acid (LA). Herein, an intelligent nanoadjuvant MOF@LOD-siRNA@Lips-FA (MLSLF) was developed by loading lactate oxidase (LOD) and monocarboxylate transporter 4 (MCT4)-inhibiting siRNA into Fe-MOF and further coated with folate-liposomes (FA-lip) for enhanced immunotherapy. The MLSLF could response to endogenous glutathione (GSH), resulting in the depletion of GSH and production of •OH for effective chemodynamic therapy (CDT). On one hand, the death of cancer cells would arouse immunogenic cell death (ICD) to release antigens and enhance tumor immunogenicity. Meanwhile, LOD could decompose intracellular LA to H2O2, which could further promote ICD and boost anti-tumor immune response. On the other hand, the siRNA could restrict the expression of MCT4, which would hinder the intracellular LA efflux. The combination of LOD and siRNA could reduce the LA content in TME and relieve immunosuppression TME. The in vivo results revealed that MLSLF could effectually suppress the growth of primary and distant tumors in tumor-bearing mice. Therefore, the smart MLSLF could be a synergistic anti-tumor strategy for efficient immunotherapy through the combination of enhanced ICD and LA metabolism blockade.

Shikonin reverses cancer-associated fibroblast-induced gemcitabine resistance in pancreatic cancer cells by suppressing monocarboxylate transporter 4-mediated reverse Warburg effect

BackgroundGemcitabine is a first-line chemotherapeutic agent for pancreatic cancer (PC); however, most patients who receive adjuvant gemcitabine rapidly develop resistance and recurrence. Cancer-associated fibroblasts (CAFs) are a crucial component of the tumor stroma that contribute to gemcitabine-resistance. There is thus an urgent need to find a novel therapeutic strategy to improve the efficacy of gemcitabine in PC cells under CAF-stimulation. PurposeTo investigate if shikonin potentiates the therapeutic effects of gemcitabine in PC cells with CAF-induced drug resistance. MethodsPC cell-stimulated fibroblasts or primary CAFs derived from PC tissue were co-cultured with PC cells to evaluate the ability of shikonin to improve the chemotherapeutic effects of gemcitabine in vitro and in vivo. Glucose uptake assay, ATP content analysis, lactate measurement, real-time PCR, immunofluorescence staining, western blot, and plasmid transfection were used to investigate the underlying mechanism. ResultsCAFs were innately resistant to gemcitabine, but shikonin suppressed the PC cell-induced transactivation and proliferation of CAFs, reversed CAF-induced resistance, and restored the therapeutic efficacy of gemcitabine in the co-culture system. In addition, CAFs underwent a reverse Warburg effect when co-cultured with PC cells, represented by enhanced aerobic glycolytic metabolism, while shikonin reduced aerobic glycolysis in CAFs by reducing their glucose uptake, ATP concentration, lactate production and secretion, and glycolytic protein expression. Regarding the mechanism underlying these sensitizing effects, shikonin suppressed monocarboxylate transporter 4 (MCT4) expression and cellular membrane translocation to inhibit aerobic glycolysis in CAFs. Overexpression of MCT4 accordingly reversed the inhibitory effects of shikonin on PC cell-induced transactivation and aerobic glycolysis in CAFs, and reduced its sensitizing effects. Furthermore, shikonin promoted the effects of gemcitabine in reducing the growth of tumors derived from PC cells and CAF co-inoculation in BALB/C mice, with no significant systemic toxicity. ConclusionThese results indicate that shikonin reduced MCT4 expression and activation, resulting in inhibition of aerobic glycolysis in CAFs and overcoming CAF-induced gemcitabine resistance in PC. Shikonin is a promising chemosensitizing phytochemical agent when used in combination with gemcitabine for PC treatment. The results suggest that disrupting the metabolic coupling between cancer cells and stromal cells might provide an attractive strategy for improving gemcitabine efficacy.