Microbial Metabolite Butyrate Research Articles

Clinical Trial Evidence of the Gut Microbial Metabolite Butyrate in Hypertension.

Clinical Trial Evidence of the Gut Microbial Metabolite Butyrate in Hypertension.

Abstract 6690: Gut microbial metabolite butyrate facilitates antitumor efficacy of telomerase-specific oncolytic adenovirus via MHC-I and cGAS-STING pathway activation

Abstract Introduction: Gut microbiota has been reported to have a potential to modulate tumor sensitivity to chemo- or immuno-therapies although the underlying mechanism is still unclear. Oncolytic virotherapy is a promising antitumor treatment that selectively induces oncolytic cell death in tumor cells. We have previously developed OBP-702, a telomerase-specific oncolytic adenovirus armed with the p53 tumor suppressor gene, highlighting potent antitumor effects across different cancer types. To explore the potential of gut microbial metabolites, particularly butyrate, in augmenting the antitumor efficacy of oncolytic virotherapy. Materials and Methods: We assessed the synergistic antitumor effects of butyrate and OBP-702 in cytotoxic assay using two human (HCT116, SW48) and two murine (CT26, MC38) colorectal cancer cell lines in vitro, and the in vivo antitumor effects in subcutaneous tumor models using HCT116 and CT26. We explored underlying mechanisms of the synergistic effects, focusing on the influences of butylate on viral infectivity via Coxsackie-Adenovirus Receptor (CAR) and integrins, and antitumor immunity via tumor MHC-I expression and CD8-positive T cells. Results: Butyrate and OBP-702 showed potent synergistic effects in all four cell lines in vitro, and the combination suppressed tumor growth significantly in HCT116 and CT26 subcutaneous tumors compared to each monotherapy. These synergistic effects were produced by butyrate increasing the potential of OBP-702 by enhancing viral infection efficiency via upregulating expressions of CAR and integrins on tumor cells. Butyrate also increased MHC-I expression on tumor cells by activating the cGAS-STING pathway, leading to increased CXCL10 expression, which led to activation of antitumor immunity through recruitment of CD8-positive T cells in tumor tissues. The synergistic effects of butyrate and OBP-702 were proved in an orthotopic colorectal tumor model with liver metastases using CT26 cells expressing luciferase, in which this combination not only reduced tumor growth, but also improved survival by activating antitumor immunity via CD8-positive T cells. Conclusion: Butyrate and OBP-702 showed synergistic antitumor effects via activation of systemic antitumor immunity in addition to direct effects of butyrate on viral cytotoxic potential, which provides valuable insights into the development of innovative cancer treatment strategies. Citation Format: Masaki Sakamoto. Gut microbial metabolite butyrate facilitates antitumor efficacy of telomerase-specific oncolytic adenovirus via MHC-I and cGAS-STING pathway activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6690.

Microbial metabolite butyrate promotes anti-PD-1 antitumor efficacy by modulating T cell receptor signaling of cytotoxic CD8 T cell

ABSTRACT Recent studies have demonstrated that the antitumor immunity of immune cells can be modulated by gut microbiota and their metabolites. However, the underlying mechanisms remain unclear. Here, we showed that the serum butyric acid level is positively correlated with the expression of programmed cell death-1 (PD-1) on circulating CD8+ and Vγ9 Vδ2 (Vδ2+) T cells in patients with non-small cell lung cancer (NSCLC). Responder NSCLC patients exhibited higher levels of serum acetic acid, propionic acid, and butyric acid than non-responders. Depletion of the gut microbiota reduces butyrate levels in both feces and serum in tumor-bearing mice. Mechanistically, butyrate increased histone 3 lysine 27 acetylation (H3K27ac) at the promoter region of Pdcd1 and Cd28 in human CD8+ T cells, thereby promoting the expression of PD-1/CD28 and enhancing the efficacy of anti-PD-1 therapy. Butyrate supplementation promotes the expression of antitumor cytokines in cytotoxic CD8+ T cells by modulating the T-cell receptor (TCR) signaling pathway. Collectively, our findings reveal that the metabolite butyrate of the gut microbiota facilitates the efficacy of anti-PD-1 immunotherapy by modulating TCR signaling of cytotoxic CD8 T cells, and is a highly promising therapeutic biomarker for enhancing antitumor immunity.

Decreased YB-1 expression denervates brown adipose tissue and contributes to age-related metabolic dysfunction.

Thermogenesis in brown adipose tissue (BAT) declines with aging, however, the underlying mechanism remains unclear. Here, we show that the expression of Y-box binding protein 1 (YB-1), a critical DNA/RNA binding protein, decreased in the BAT of aged mice due to the reduction of microbial metabolite butyrate. Genetic ablation of YB-1 in the BAT accelerated diet-induced obesity and BAT thermogenic dysfunction. In contrast, overexpression of YB-1 in the BAT of aged mice was sufficient to promote BAT thermogenesis, thus alleviating diet-induced obesity and insulin resistance. Interestingly, YB-1 had no direct effect on adipose UCP1 expression. Instead, YB-1 promoted axon guidance of BAT via regulating the expression of Slit2, thus potentiating sympathetic innervation and thermogenesis. Moreover, we have identified that a natural compound Sciadopitysin, which promotes YB-1 protein stability and nuclear translocation, alleviated BAT aging and metabolic disorders. Together, we reveal a novel fat-sympathetic nerve unit in regulating BAT senescence and provide a promising strategy against age-related metabolic disorders.

Gut Microbial Metabolite Butyrate and Its Therapeutic Role in Inflammatory Bowel Disease: A Literature Review.

Background and objective: Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic inflammatory disorder characterized by aberrant immune responses and compromised barrier function in the gastrointestinal tract. IBD is associated with altered gut microbiota and their metabolites in the colon. Butyrate, a gut microbial metabolite, plays a crucial role in regulating immune function, epithelial barrier function, and intestinal homeostasis. In this review, we aim to present an overview of butyrate synthesis and metabolism and the mechanism of action of butyrate in maintaining intestinal homeostasis and to discuss the therapeutic implications of butyrate in IBD. Methods: We searched the literature up to March 2023 through PubMed, Web of Science, and other sources using search terms such as butyrate, inflammation, IBD, Crohn's disease, and ulcerative colitis. Clinical studies in patients and preclinical studies in rodent models of IBD were included in the summary of the therapeutic implications of butyrate. Results: Research in the last two decades has shown the beneficial effects of butyrate on gut immune function and epithelial barrier function. Most of the preclinical and clinical studies have shown the positive effect of butyrate oral supplements in reducing inflammation and maintaining remission in colitis animal models and IBD patients. However, butyrate enema showed mixed effects. Butyrogenic diets, including germinated barley foodstuff and oat bran, are found to increase fecal butyrate concentrations and reduce the disease activity index in both animal models and IBD patients. Conclusions: The current literature suggests that butyrate is a potential add-on therapy to reduce inflammation and maintain IBD remission. Further clinical studies are needed to determine if butyrate administration alone is an effective therapeutic treatment for IBD.

Butyrate ameliorates chronic alcoholic central nervous damage by suppressing microglia-mediated neuroinflammation and modulating the microbiome-gut-brain axis

BackgroundAlcohol abuse triggers neuroinflammation, leading to neuronal damage and further memory and cognitive impairment. Few satisfactory advances have been made in the management of alcoholic central nervous impairment. Therefore, novel and more practical treatment options are urgently needed. Butyrate, a crucial metabolite of short-chain fatty acids (SCFAs), has been increasingly demonstrated to protect against numerous metabolic diseases. However, the impact of butyrate on chronic alcohol consumption-induced central nervous system (CNS) lesions remains unknown. MethodsIn this study, we assessed the possible effects and underlying mechanisms of butyrate on the attenuation of alcohol-induced CNS injury in mice. Firstly, sixty female C57BL/6 J mice were randomly divided into 4 groups: pair-fed (PF) group (PF/CON), alcohol-fed (AF) group (AF/CON), PF with sodium butyrate (NaB) group (PF/NaB) and AF with NaB group (AF/NaB). Each group was fed a modified Lieber-DeCarli liquid diet with or without alcohol. After six weeks of feeding, the mice were euthanized and the associated indicators were investigated. ResultsAs indicated by the behavioral tests and brain morphology, dietary NaB administration significantly ameliorated aberrant behaviors, including locomotor hypoactivity, anxiety disorder, depressive behavior, impaired learning, spatial recognition memory, and effectively reduced chronic alcoholic central nervous system damage. To further understand the underlying mechanisms, microglia-mediated inflammation and the associated M1/M2 polarization were measured separately. Firstly, pro-inflammatory TNF-α, IL-1β, and IL-6 in brain and peripheral blood circulation were decreased, but IL-10 were increased in the AF/NaB group compared with the AF/CON group. Consistently, the abnormal proportions of activated and resting microglial cells in the hippocampus and cortex regions after excessive alcohol consumption were significantly reduced with NaB treatment. Moreover, the rectification of microglia polarization (M1/M2) imbalance was found after NaB administration via binding GPR109A, up-regulating the expression of PPAR-γ and down-regulating TLR4/NF-κB activation. In addition to the direct suppression of neuroinflammation, intriguingly, dietary NaB intervention remarkably increased the levels of intestinal tight junction protein occludin and gut morphological barrier, attenuated the levels of serum lipopolysaccharide (LPS) and dysbiosis of gut microbiota, suggesting that NaB supplementation effectively improved the integrity and permeability of gut microecology. Finally, the neurotransmitters including differential Tryptophan (Trp) and Kynurenine (Kyn) were found with dietary NaB administration, which showed significantly altered and closely correlated with the gut microbiota composition, demonstrating the complex interactions in the microbiome-gut-brain axis involved in the efficacy of dietary NaB therapy for alcoholic CNS lesions. ConclusionDietary microbial metabolite butyrate supplementation ameliorates chronic alcoholic central nervous damage and improves related memory and cognitive functions through suppressing microglia-mediated neuroinflammation by GPR109A/PPAR-γ/TLR4-NF-κB signaling pathway and modulating microbiota−gut−brain axis.

Gut microbial metabolite butyrate improves anticancer therapy by regulating intracellular calcium homeostasis.

Gut microbiota are recognized to be important for anticancer therapy, yet the underlying mechanism is not clear. Here, through the analysis of clinical samples, we identify the mechanism by which the gut microbial metabolite butyrate inhibits HCC and then explore new strategies for HCC treatment. In our study, we demonstrate that gut microbial metabolite butyrate improves anticancer therapy efficacy by regulating intracellular calcium homeostasis. Using liquid chromatography-mass spectrometry analysis, we found that butyrate metabolism is activated in HCC patients compared with healthy individuals. Butyrate levels are lower in the plasma of HCC patients by gas chromatography-mass spectrometry (GC-MS) analysis. Butyrate supplementation or depletion of short-chain Acyl-CoA dehydrogenase (SCAD) gene (ACADS), encoding a key enzyme for butyrate metabolism, significantly inhibits HCC proliferation and metastasis. The profiling analysis of genes upregulated by butyrate supplementation or ACADS knockdown reveals that calcium signaling pathway is activated, leading to dysregulation of intracellular calcium homeostasis and production of reactive oxygen species. Butyrate supplementation improves the therapy efficacy of a tyrosine kinase inhibitor sorafenib. On the basis of these findings, we developed butyrate and sorafenib coencapsulated mPEG-PLGA-PLL nanoparticles coated with anti-GPC3 antibody (BS@PEAL-GPC3) to prolong the retention time of drugs and enhance drug targeting, leading to high anticancer efficacy. BS@PEAL-GPC3 nanoparticles significantly reduce HCC progression. In addition, BS@PEAL-GPC3 nanoparticles display excellent HCC targeting with excellent safety. In conclusion, our findings provide new insight into the mechanism by which the gut microbial metabolites inhibit HCC progression, suggesting a translatable therapeutics approach to enhance the clinical targeted therapeutic efficacy.

Maternal treatment with sodium butyrate reduces the development of autism-like traits in mice offspring

Several studies indicate a relationship between maternal gut microbiota alteration and increased risk of autism spectrum disorders (ASD) in offspring. The possibility of compensating for such metabolic dysfunction at a very early stage of disease via maternal treatment has not been enough explored. Here, we examined in BTBR mouse model of ASD the effect of maternal treatment with the gut microbial metabolite butyrate (BUT) on the behavioral and synaptic plasticity deficits in juvenile and adult offspring. We show that BUT treatment of BTBR dams rescues the social and partially the repetitive behavior deficits in the offspring. In addition, maternal BUT implementation prevents the cerebellar cortex hypertrophy as well as the Purkinje cells firing and long-term synaptic plasticity deficits in BTBR mice. Our results demonstrate, for the first time, that maternal BUT treatment can improve ASD-like symptoms in offspring thus providing new directions for the early treatment of neurodevelopmental disorders.

Microbial metabolite butyrate promotes induction of IL-10+IgM+ plasma cells.

The microbially-derived short-chain fatty acid butyrate is a central inhibitor of inflammatory innate and adaptive immune responses. Emerging evidence suggests that butyrate induces differentiation of IL-10-producing (IL-10+) regulatory B cells. However, the underlying mechanisms of butyrate-driven modulation of B cell differentiation are not fully defined. Given the dominant role of regulatory plasma cells (PCs) as the main source of anti-inflammatory cytokines including IL-10 and the observation that butyrate also induces the differentiation of PCs, we here investigated the effect of the microbial metabolite butyrate on the induction of regulatory IL-10+ PCs and underlying mechanisms. Here we show that butyrate induces the differentiation of IL-10+IgM+ PCs. Ex vivo, butyrate, but hardly propionate, another microbially-derived short-chain fatty acid, induced the differentiation of IL-10+IgM+ CD138high PCs from isolated splenic murine B cells. In vivo, administration of butyrate via drinking water or by daily intraperitoneal injection increased the number of IL-10+IgM+ CD138high PCs in the spleens of Ovalbumin (Ova)/complete Freund’s adjuvant-immunized mice. The induction of these regulatory PCs was associated with an increase of anti-Ova IgM, but a reduction of anti-Ova class-switched pathogenic IgG2b serum antibodies. Based on the knowledge that butyrate inhibits histone deacetylases (HDACs) thereby increasing histone acetylation, we identified here that HDAC3 inhibition was sufficient to induce PC differentiation and IL-10+ expression. Furthermore, reduced mitochondrial superoxide levels following butyrate treatment and HDAC3 inhibition were necessary for PC differentiation, but not IL-10 expression. In summary, the microbial metabolite butyrate promotes the differentiation of IgM+ PCs and their expression of IL-10. HDAC3 inhibition may be involved as an underlying pathway for both PC differentiation and IL-10 expression, while reduced mitochondrial superoxide levels are crucial only for PC differentiation. The induction of regulatory IL-10+IgM+ PCs and the inhibition of class switching to antigen-specific pathogenic IgG subclasses might represent important pathways of butyrate to limit inflammation.

Potential Clinical Applications of the Postbiotic Butyrate in Human Skin Diseases.

Human skin is the largest organ and the most external interface between the environment and the body. Vast communities of viruses, bacteria, archaea, fungi, and mites, collectively named the skin microbiome (SM), cover the skin surface and connected structures. Skin-resident microorganisms contribute to the establishment of cutaneous homeostasis and can modulate host inflammatory responses. Imbalances in the SM structure and function (dysbiosis) are associated with several skin conditions. Therefore, novel target for the skincare field could be represented by strategies, which restore or preserve the SM natural/individual balance. Several of the beneficial effects exerted by the SM are aroused by the microbial metabolite butyrate. Since butyrate exerts a pivotal role in preserving skin health, it could be used as a postbiotic strategy for preventing or treating skin diseases. Herein, we describe and share perspectives of the potential clinical applications of therapeutic strategies using the postbiotic butyrate against human skin diseases.

Gut microbiota-derived butyrate regulates gut mucus barrier repair by activating the macrophage/WNT/ERK signaling pathway.

Ulcerative colitis (UC) is majorly associated with dysregulation of the dynamic cross-talk among microbial metabolites, intestinal epithelial cells, and macrophages. Several studies have reported the significant role of butyrate in host-microbiota communication. However, whether butyrate provides anti-inflammatory profiles in macrophages, thus contributing to UC intestinal mucus barrier protection, has currently remained elusive. In the current study, we found that butyrate increased mucin production and the proportion of mucin-secreting goblet cells in the colon crypt in a macrophage-dependent manner by using clodronate liposomes. Furthermore, in vivo and in vitro studies were conducted, validating that butyrate facilitates M2 macrophage polarization with the elevated expressions of CD206 and arginase-1 (Arg1). In macrophages/goblet-like LS174T cells co-culture systems, butyrate-primed M2 macrophages significantly enhanced the expression of mucin-2 (MUC2) and SPDEF (goblet cell marker genes) than butyrate alone, while blockade of WNTs secretion or ERK1/2 activation significantly decreased the beneficial effect of butyrate-primed macrophages on goblet cell function. Additionally, the adoptive transfer of butyrate-induced M2 macrophages facilitated the generation of goblet cells and mucus restoration following dextran sulfate sodium (DSS) insult. Taken together, our results revealed a novel mediator of macrophage-goblet cell cross-talk associated with the regulation of epithelial barrier integrity, implying that the microbial metabolite butyrate may serve as a candidate therapeutic target for UC.

EPITHELIAL DUOX2 ACTIVATION INCREASES GUT PERMEABILITY AND BACTERIAL TRANSLOCATION THAT IS RESCUED WITH BUTYRATE SUPPLEMENTATION

Abstract BACKGROUND Inflammatory bowel diseases (IBD) are chronic pathologies characterized by dysbiosis, defects in epithelial barrier function, and increased redox stress. Dysbiosis in IBD involves an expansion of Proteobacteria and a reduction of Firmicutes, which produce metabolites important in maintaining gut homeostasis. The epithelial NADPH oxidase dual oxidase 2 (DUOX2) catalyzes the production of hydrogen peroxide (H2O2) and is the only gene consistently altered in IBD patients in association with dysbiosis and before the onset of disease. However, the functional consequence of DUOX2 activation in IBD is not understood. Using models of dysbiosis leading to DUOX2 activation, we aimed to dissect the contribution of DUOX2 activity to the defects in epithelial barrier function observed in IBD. METHODS villin-TLR4 (vTLR4) mice, which express a constitutively active form of TLR4 in colonic epithelial cells (CECs) and have increased activation of DUOX2, vTLR4-DUOX2-KO mice, and their wild-type (WT) littermates were euthanized. Livers were collected for permeability assessment by bacterial translocation. Colonic tissue was collected for RNA-sequencing and isolation of CECs for gene expression determinations by qPCR. Separately, vTLR4 mice and littermates were treated with butyrate in drinking water. Tissue was harvested for the same determinations and for measurement of epithelial H2O2 production via Amplex Red. Colonoids from WT mice were treated with butyrate and stimulated with IFNγ or heat-killed adherent invasive Escherichia coli. H2O2 production and gene expression of Duox2 were determined. RESULTS RNA-sequencing revealed that abrogation of DUOX2 activity downregulated cytokine-mediated signaling and cytokine production pathways, including tumor necrosis factors and key chemotactic proteins such as CXCL1 and CXCL2. Similarly, expression of Tnfa, Cxcl1, and Cxcl2 was significantly downregulated to WT levels in vTLR4-DUOX2-KO mice. vTLR4 mice had increased bacterial translocation, which was rescued by deletion of DUOX2. Butyrate treatment inhibited epithelial H2O2 response to stimuli in vitro, which was accompanied by a reduction in Duox2 transcripts. In vivo, butyrate treatment of vTLR4 mice significantly reduced epithelial production of H2O2, bacterial translocation to the liver, and led to a downregulation of Tnfa, Cxcl1, and Cxcl2 transcripts. CONCLUSIONS Chronic DUOX2 activity leads to defects in epithelial barrier function resulting in increased bacterial translocation. This leads to an increase in proinflammatory cytokines and chemokines. The microbial metabolite butyrate blocked DUOX2 activity, rescuing intestinal permeability and reducing bacterial translocation and inflammatory cytokine gene expression. We posit that therapies aimed at controlling DUOX2 activity through microbiome or metabolome-targeted approaches may be beneficial in IBD.

Butyrate and the Intestinal Epithelium: Modulation of Proliferation and Inflammation in Homeostasis and Disease.

The microbial metabolite butyrate serves as a link between the intestinal microbiome and epithelium. The monocarboxylate transporters MCT1 and SMCT1 are the predominant means of butyrate transport from the intestinal lumen to epithelial cytoplasm, where the molecule undergoes rapid β-oxidation to generate cellular fuel. However, not all epithelial cells metabolize butyrate equally. Undifferentiated colonocytes, including neoplastic cells and intestinal stem cells at the epithelial crypt base preferentially utilize glucose over butyrate for cellular fuel. This divergent metabolic conditioning is central to the phenomenon known as “butyrate paradox”, in which butyrate induces contradictory effects on epithelial proliferation in undifferentiated and differentiated colonocytes. There is evidence that accumulation of butyrate in epithelial cells results in histone modification and altered transcriptional activation that halts cell cycle progression. This manifests in the apparent protective effect of butyrate against colonic neoplasia. A corollary to this process is butyrate-induced inhibition of intestinal stem cells. Yet, emerging research has illustrated that the evolution of the crypt, along with butyrate-producing bacteria in the intestine, serve to protect crypt base stem cells from butyrate’s anti-proliferative effects. Butyrate also regulates epithelial inflammation and tolerance to antigens, through production of anti-inflammatory cytokines and induction of tolerogenic dendritic cells. The role of butyrate in the pathogenesis and treatment of intestinal neoplasia, inflammatory bowel disease and malabsorptive states is evolving, and holds promise for the potential translation of butyrate’s cellular function into clinical therapies.

Gut microbial metabolites facilitate anticancer therapy efficacy by modulating cytotoxic CD8+ T cell immunity

Recent studies in both mice and humans have suggested that gut microbiota could modulate tumor responsiveness to chemo- or immunotherapies. However, the underlying mechanism is not clear yet. Here, we found that gut microbial metabolites, especially butyrate, could promote the efficacy of oxaliplatin by modulating CD8+ Tcell function in the tumor microenvironment. Butyrate treatment directly boosted the antitumor cytotoxic CD8+ Tcell responses both invitro and invivo in an ID2-dependent manner by promoting the IL-12 signaling pathway. In humans, the oxaliplatin responder cancer patients exhibited a higher amount of serum butyrate than did non-responders, which could also increase ID2 expression and function of human CD8+ Tcells. Together, our findings suggest that the gut microbial metabolite butyrate could promote antitumor therapeutic efficacy through the ID2-dependent regulation of CD8+ Tcell immunity, indicating that gut microbial metabolites could be effective as a part of cancer therapy.

Protective action of the microbial metabolite butyrate against cardiomyocyte hypertrophy

Abstract Introduction Short-chain fatty acids are one of the gut microbial metabolites that may influence host physiology. We previously reported that gut dysbiosis was associated with heart failure, and that the proportions of butyrate-producing bacteria diminished prominently in the gut of patients with heart failure. Purpose We investigated the molecular mechanism of butyrate and investigated the protective mechanism against heart failure. Methods We searched for G protein-coupled receptors for short-chain fatty acids using single-cell transcriptome analysis of cardiomyocytes and non-cardiomyocytes isolated from murine hearts. In addition, we examined the effects of butyrate on endothelin-1 (ET1) or isoproterenol-induced hypertrophic responses and histone deacetylase (HDAC) activities in cultured neonatal rat cardiomyocytes. Results Single-cell transcriptome analysis and co-expression network analysis revealed that G protein-coupled receptors for short-chain fatty acid receptors were not expressed in cardiomyocytes and that Olfr78 was expressed in vascular smooth muscle cells in the heart. Treatment with butyrate inhibited ET1-induced hypertrophic growth and up-regulation of the genes such as Nppa, Acta1, and Myh7 in cultured rat neonatal cardiomyocytes. Moreover, butyrate increased the acetylation levels of histone H3, indicating that butyrate has an inhibitory effect on HDAC in cardiomyocytes. In addition, treatment with butyrate caused up-regulation of Inpp5f, encoding inositol polyphosphate-5-phosphatase f, which was associated with a significant decrease in the phosphorylation levels of Akt. These results suggest that butyrate may act as HDAC inhibitor to increase Inpp5f gene expression, leading to the activation of Akt-glycogen synthase kinase 3beta (Gsk3beta) pathway, and thereby protect against hypertrophic responses. Conclusion There was no known GPCR for short-chain fatty acid expressed in cardiomyocytes. However, butyrate suppressed cardiomyocyte hypertrophy through epigenetic modification of gene expression. Our results may uncover a potential role of the dysbiosis of intestinal microbiota in the pathogenesis of cardiac hypertrophy and failure. Funding Acknowledgement Type of funding source: None

The Active Components in Whole Grain Wheat for Colon Cancer Prevention: Synergistic Effects Between Phytochemical Alkylresorcinols and Fiber Microbial Metabolite Butyrate

Abstract Objectives Wheat bran (WB) is a rich source of dietary fiber and phytochemicals with health-promoting properties. However, the active components especially the interaction between different components in whole grain (WG) wheat have not been fully explored. This study aimed to investigate whether WB phytochemicals, alkylresorcinols (ARs), and the active intestinal microbial metabolite of fiber, butyrate, could synergistically suppress human colon cancer cells. Methods Cell viability was determined by MTT assay in HCT-116 and HT-29 cells after the treatments of the combination of ARs, C21 and C19, and NaB, respectively. Apoptosis was determined by Cell Death ELISA Kit. The further mechanism was investigated by western blot associated with apoptosis, autophagy, and ER stress pathways. The C21 levels in gastrointestinal tract were measured by HPLC in mice treated with human-relevant doses of C21. Isobologram analysis was employed for the determination of synergistic or additive anticancer effects of the co-treatments of AR and NaB. Results The combination of C21 or C19 and butyrate synergistically inhibited the growth of colon cancer cells and induced apoptosis. Further mechanistic studies demonstrated that the co-treatment of C21 and butyrate induced significant upregulations in cleaved Poly(ADP-ribose) polymerase (PARP), cleaved caspase 3, p53 upregulated modulator of apoptosis (PUMA), cytochrome C, lipid-conjugated membrane-bound form of microtubule-associated protein 1A/1B-light chain 3 (LC3-II), and C/EBP homologous protein (CHOP) expressions. Notably, the C21 concentrations in the large intestinal tract of mice treated with human-relevant doses of C21, were from 0.86 to 1.78 μmol/g, suggesting the C21 doses used in vitro may be achievable after daily WG wheat intake. Conclusions We demonstrated for the first time that phytochemical component ARs and the microbial metabolites of WB fiber exhibit synergistic anticancer effects in human colon cancer cells, which may be associated with the induction of apoptosis, autophagy, and ER stress pathways. The present study provides novel insights into the understanding of the chemo-preventive effects of WG wheat against CRC. However, the mechanism of the synergistic anticancer effect of phytochemicals and fiber is complicated and still needs to be further investigated in vivo. Funding Sources USDA NIFA R01.

Weaning Alters Intestinal Gene Expression Involved in Nutrient Metabolism by Shaping Gut Microbiota in Pigs.

Weaning transition usually impairs intestinal architecture and functions and results in gut-associated disorders in pigs. Understanding the changes in intestinal transcriptome and gut microbiota during weaning transition is important for elucidating the underlying mechanism of weaning stress. In the present study, we performed RNA-seq to determine the changes in intestinal transcriptome and 16S rRNA sequencing to measure the gut microbiota changes in the weaning transition. Transcriptome results indicated that weaning transition altered intestinal gene expression involved in nutrient transport and metabolism. Regarding fatty metabolism, fatty acid-binding protein 1 (FABP1), acyl-CoA dehydrogenase (ACADSB), and carnitine palmitoyltransferase 2 (CPT2) expression in the intestine was decreased by weaning. Genes related to bile acid metabolism were increased by weaning, including FABP6, farnesoid X receptor (FXR or NR1H4) and organic solute transporter-α (SLC51A). In addition, genes associated with oxidative stress were altered by weaning transition, including decreased catalase (CAT) and lactate dehydrogenase (LDHA) and increased glutathione peroxidase 2 (GPX2) and superoxide dismutase 3 (SOD3). Results of microbiota composition showed that the Firmicutes abundance and Firmicutes/Bacteroidetes ratio were increased and that the Proteobacteria abundance in the fecal microbiota was decreased by the weaning process; during the weaning transition, the Bacteroides and Fusobacterium abundances decreased markedly, and these bacteria nearly disappeared, while the Prevotella abundance showed a marked increase. Moreover, the levels of the microbial metabolites butyrate and acetate increased with changes in gut microbiota composition. In addition, predictive metagenome by PICRUSt analysis showed that the pathways related to D-glutamine and D-glutamate metabolism, citrate cycle (TCA cycle), peroxisome proliferators-activated receptor (PPAR) signaling, alpha-linolenic acid metabolism were decreased and the pathway related to retinol metabolism was increased in the gut microbiota of piglets during weaning transition. Our results showed that early weaning alters intestinal gene expression involved in nutrient metabolism, which may be due to the changes in microbiota composition.

Butyrate Ameliorates Antibiotic-Driven Type 1 Diabetes in the Female Offspring of Nonobese Diabetic Mice.

Maternal gut dysbiosis affects the development of the offspring immune system. Our previous study has indicated that microbial metabolite butyrate directly shapes pancreatic immune tolerance and dampens type 1 diabetes (T1D) progression. Therefore, maternal butyrate intervention may protect their offspring from maternal gut dysbiosis-accelerated T1D. To test this, pregnant nonobese diabetic (NOD) mice were treated with vancomycin in drinking water with or without a butyrate-supplemented diet during gestation and nursing (oral vancomycin is used to induce maternal gut dysbiosis). Three weeks after delivery, T1D-associated innate and adaptive immune cells were detected to investigate the effects of butyrate on the vancomycin-exacerbated pancreatic immune disorder in dams and pups. The results showed that butyrate inhibited maternal vancomycin-exacerbated secretion of proinflammation cytokines (interferon γ and interleukin-1β) and maternal vancomycin-exacerbated recruitment of interferon γ+ T cells (cytotoxic T lymphocytes 1 cells and T helper type 1 cells) in the pancreas of the female offspring, thus dampening T1D development. The protection may be due to butyrate inhibiting the activation of pancreatic dendritic cells (DCs). Our data thus demonstrate that maternal gut dysbiosis can exacerbate pancreatic-directed autoimmunity in the female offspring through T cell- and DC-associated mechanisms that are inhibited by butyrate.

Butyrate protects against high-fat diet-induced atherosclerosis via up-regulating ABCA1 expression in apolipoprotein E-deficiency mice.

The gut microbial metabolite butyrate is linked to the modulation of metabolic disease. The mechanism by which butyrate effects in atherosclerosis is unknown. Hence, the present investigation into effects of butyrate on high-fat diet-fed ApoE-/- mice after 16 weeks' administration. Gut microbiota composition was analysed via 16S rRNA gene sequencing of caecal contents. The effects of butyrate on atherosclerosis were evaluated in vivo using the ApoE-/- mice model. Serum lipids and glucose were analysed for physiological changes and differentially expressed genes in liver samples were identified by hepatic transcriptome profiling. The proteins involved in reverse cholesterol transport were quantified by Western blot and immunohistochemical staining. Finally, the up-regulatory effects of butyrate on ATP-binding cassette sub-family A member 1 (ABCA1) were further evaluated in RAW 264.7 cells along with role of specificity protein 1 by inhibition and silencing. Oral gavage of butyrate altered microbiota composition and enhanced gut microbial diversity that was decreased by high fat diet (HFD). Butyrate treatment significantly inhibited the HFD-induced atherosclerosis as well as hepatic steatosis without changing body weight gain in ApoE-/- mice. Butyrate had metabolic effects on the liver by regulation of gene expression involved in lipid/glucose metabolism. Furthermore, ABCA1 was significantly induced by butyrate in vivo, ex vivo and in vitro and Sp1 pathway was identified as a potential mechanism. Butyrate ameliorates HFD-induced atherosclerosis in ApoE-/- mice via ABCA1-mediated cholesterol efflux in macrophages, which suggesting a promising therapeutic strategy for protecting against atherosclerosis.

LSD1 mediates microbial metabolite butyrate-induced thermogenesis in brown and white adipose tissue

ObjectiveThe gut microbiota regulates thermogenesis to benefit metabolic homeostasis at least partially via its metabolite butyrate, and the underlying mechanisms of this regulation are still unclear. In this study, we aim to investigate the role of lysine specific demethylase (LSD1), a histone demethylase and important regulator of thermogenesis, in mediating gut microbial metabolite butyrate regulation of thermogenesis. MethodsThe antibiotic cocktail (ABX) was administrated to deplete gut microbiota. Adipose-specific LSD1 knockout mice (LSD1 aKO) were generated by crossing LSD1-lox/lox with adiponectin-cre mice and sodium butyrate and dietary fiber inulin was administrated through oral-gavage. Primary stromal vascular cells were isolated from adipose tissues and differentiated to adipocytes for studying butyrate effects on adipocyte thermogenesis. ResultsThe antibiotic cocktail (ABX)-mediated depletion of the gut microbiota in mice downregulated the expression of LSD1 in both brown adipose tissue (BAT) and subcutaneous white adipose tissue (scWAT) in addition to uncoupling protein 1 (UCP1) and body temperature. Gavage of the microbial metabolite butyrate in ABX-treated mice reversed the thermogenic functional impairment and LSD1 expression. The adipose-specific ablation of LSD1 in mice attenuated the butyrate-mediated induction of thermogenesis and energy expenditure. Notably, our results showed that butyrate directly increased the expression of LSD1 and UCP1 as well as butyrate transporter monocarboxylate transporter 1 (MCT1) and catabolic enzyme acyl-CoA medium-chain synthetase 3 (ACSM3) in ex vivo cultured adipocytes. The inhibition of MCT1 blocked the effects of butyrate in adipocytes. Furthermore, the butyrate-mediated prevention of diet-induced obesity (DIO) through increased thermogenesis was attenuated in LSD1 aKO mice. Moreover, after gavaging HFD-fed mice with the dietary fiber inulin, a substrate of microbial fermentation that rapidly produces butyrate, thermogenesis in both BAT and scWAT was increased, and DIO was decreased; however, these beneficial metabolic effects were blocked in LSD1 aKO mice. ConclusionsTogether, our results indicate that the microbial metabolite butyrate regulates thermogenesis in BAT and scWAT through the activation of LSD1.