Short-chain Fatty Acid Receptor Research Articles

GPR41 Regulates the Proliferation of BRECs via the PIK3-AKT-mTOR Pathway

Short-chain fatty acids (SCFAs) play a pivotal role in regulating the proliferation and development of bovine rumen epithelial cells (BRECs). G protein-coupled receptor 41 (GPR41) is involved in the signal transduction in BRECs as a receptor for SCFAs. Nevertheless, the impact of GPR41 on the proliferation of BRECs has not been reported. The results of this research showed that the knockdown of GPR41 (GRP41KD) decreased BRECs proliferation compared with the wild-type BRECs (WT) (p < 0.001). The RNA sequencing (RNA-seq) analysis showed that the gene expression profiles differed between WT and GPR41KD BRECs, with the major differential genes enriched in phosphatidylinositol 3-kinase (PIK3) signaling, cell cycle, and amino acid transport pathways (p < 0.05). The transcriptome data were further validated by Western blot and qRT-PCR. It was evident that the GPR41KD BRECs downregulated the level of the PIK3-Protein kinase B (AKT)-mammalian target of the rapamycin (mTOR) signaling pathway core genes, such as PIK3, AKT, eukaryotic translation initiation factor 4E binding protein 1 (4EBP1) and mTOR contrasted with the WT cells (p < 0.01). Furthermore, the GPR41KD BRECs downregulated the level of Cyclin D2 p < 0.001) and Cyclin E2 (p < 0.05) compared with the WT cells. Therefore, it was proposed that GPR41 may affect the proliferation of BRECs by mediating the PIK3-AKT-mTOR signaling pathway.

Inhibition of inflammatory microglia by dietary fiber and short-chain fatty acids

Microglia play a vital role maintaining brain homeostasis but can also cause persistent neuroinflammation. Short-chain fatty acids (SCFAs) produced by the intestinal microbiota have been suggested to regulate microglia inflammation indirectly by signaling through the gut-brain axis or directly by reaching the brain. The present work evaluated the anti-inflammatory effects of SCFAs on lipopolysaccharide (LPS)-stimulated microglia from mice fed inulin, a soluble fiber that is fermented by intestinal microbiota to produce SCFAs in vivo, and SCFAs applied to primary microglia in vitro. Feeding mice inulin increased SCFAs in the cecum and in plasma collected from the hepatic portal vein. Microglia isolated from mice fed inulin and stimulated with LPS in vitro secreted less tumor necrosis factor α (TNF-α) compared to microglia from mice not given inulin. Additionally, when mice were fed inulin and injected i.p with LPS, the ex vivo secretion of TNF-α by isolated microglia was lower than that secreted by microglia from mice not fed inulin and injected with LPS. Similarly, in vitro treatment of primary microglia with acetate and butyrate either alone or in combination downregulated microglia cytokine production with the effects being additive. SCFAs reduced histone deacetylase activity and nuclear factor-κB nuclear translocation after LPS treatment in vitro. Whereas microglia expression of SCFA receptors Ffar2 or Ffar3 was not detected by single-cell RNA sequencing analysis, the SCFA transporters Mct1 and Mct4 were. Nevertheless, inhibiting monocarboxylate transporters on primary microglia did not interfere with the anti-inflammatory effects of SCFAs, suggesting that if SCFAs produced in the gut regulate microglia directly it is likely through an epigenetic mechanism following diffusion.

Maternal helminth infection protects offspring from high-fat-diet-induced obesity through altered microbiota and SCFAs.

Helminth-induced Th2 immunity and gut microbiota have been recently shown to be highly effective in modulating metabolic syndromes in animal models. This study aimed to determine whether maternal immunity and microbial factors affect the induction and development of obesity in offspring. Here, Heligomosomoides polygyrus (Hp)-infected or control female C57BL/6J mice mated with normal males and their offspring were fed a high-fat diet (HFD) for 9 weeks after weaning. Our results showed that Hp-induced maternal outcomes during gestation and lactation significantly impacted offspring metabolic phenotypes. This was evidenced by results showing that offspring from helminth-infected mothers on an HFD (Hp-offspring + HFD) gained significantly less body weight than those from uninfected mothers (Cont-offspring + HFD). Hp-offspring + HFD exhibited no Th2 phenotype but displayed a pattern of gut microbiota composition similar to that of Hp-infected mothers. Cross-fostering experiments confirmed that the helminth-induced maternal attenuation of offspring obesity was mediated through both prenatal and postnatal effects. Our results further showed that helminth-infected dams and their offspring had a markedly altered gut microbiome composition, with increased production of short-chain fatty acids (SCFAs). Intriguingly, Hp-infected mothers and Hp-offspring + HFD showed increased SCFA receptor (GPR) expression in adipose and colonic tissues compared to noninfected mothers and Cont-offspring + HFD, respectively. Moreover, SCFA supplementation to the pups of uninfected control mothers during lactation protected against HFD-induced weight gain, which corresponded with changes in gut bacterial colonization. Collectively, our findings provide new insights into the complex interaction of maternal immune status and gut microbiome, Hp infection, and the immunity and gut microbiome in obese-prone offspring in infant life.

Eucommia Bark/Leaf Extract Improves Lipid Metabolism Disorders by Affecting Intestinal Microbiota and Microbiome-Host Interaction in HFD Mice.

Eucommia bark contains many bioactive compounds and has anti-hyperlipidemic effects. However, due to the slow growth rate of the plant, there is a limited supply of this resource. Studies have demonstrated that Eucommia leaves contain active ingredients similar to those of Eucommia bark and also have anti-hyperlipidemic effects. It is not currently clear whether Eucommia leaf can be used as a substitute for Eucommia bark. Furthermore, their mechanism of action for anti-hyperlipidemia by improving the structure of the gut microbiota is also unclear. We aimed to determine the composition of the active ingredients in EBE and ELE by HPLC, establish an HFD-induced hyperlipidemia model, and combine fecal microbiota transplantation (FMT) experiments to investigate the mechanism of EBE/ELE anti-hyperlipidemia by modifying the structure of intestinal microbiota, as well as to compare the effects of EBE and ELE. Our results showed that EBE and ELE contained similar active ingredients and significantly alleviated lipid metabolism disorders and blood glucose levels in the HFD-induced hyperlipidemia model. In this study, EBE and ELE significantly reduced the relative abundance of Desulfovibrionaceae and Erysipelotrichaceae and significantly increased the relative abundance of Ruminococcaceae. They also promoted the production of short-chain fatty acids (SCFAs) and activated the gene expression of the SCFA receptors G protein-coupled receptor 41 (GPR41) and GPR43. In addition, EBE and ELE can significantly increase the expression of the fasting-induced adipose factor (Fiaf) gene in the colon and inhibit the secretion of lipoprotein lipase (LPL) in the liver, thereby inhibiting triglyceride (TG) synthesis. They also significantly activate the expression of GPR41 and GPR43 genes in the epididymal fat tissue, leading to reduced lipid accumulation in adipocytes. These effects on the target genes were associated with changes in the abundance of Desulfovibrionaceae, Erysipelotrichaceae, and Ruminococcaceae bacteria in the intestinal microbiota. Thus, regulating the relative abundance of these microbes may serve as prospective targets for EBE/ELE to influence the Fiaf-LPL gut-liver axis and the SCFAs-GPR41/GPR43 gut-fat axis. In addition, there was no significant difference in the anti-hyperlipidemic effects of ELE and EBE, suggesting that Eucommia leaf may be a suitable alternative to Eucommia bark for managing hyperlipidemia by regulating the structure of the intestinal microbiota. These findings suggest that Eucommia leaves have great potential for development as a functional food with lipid-lowering properties.

The short-chain fatty acid butyrate exerts a specific effect on VE-cadherin phosphorylation and alters the integrity of aortic endothelial cells.

Short-chain fatty acids (SCFAs) like butyrate (BUT) largely influence vascular integrity and are closely associated with the onset and progression of cardiovascular diseases. However, their impact on vascular endothelial cadherin (VEC), a major vascular adhesion and signaling molecule, is largely unknown. Here, we explored the effect of the SCFA BUT on the phosphorylation of specific tyrosine residues of VEC (Y731, Y685, and Y658), which are reported to be critical for VEC regulation and vascular integrity. Moreover, we shed light on the signaling pathway engaged by BUT to affect the phosphorylation of VEC. Thereby, we used phospho-specific antibodies to evaluate the phosphorylation of VEC in response to the SCFA sodium butyrate in human aortic endothelial cells (HAOECs) and performed dextran assays to analyze the permeability of the EC monolayer. The role of c-Src and SCFA receptors FFAR2 and FFAR3 in the induction of VEC phosphorylation was analyzed using inhibitors and antagonists for c-Src family kinases and FFAR2/3, respectively, as well as by RNAi-mediated knockdown. Localization of VEC in response to BUT was assessed by fluorescence microscopy. BUT treatment of HAOEC resulted in the specific phosphorylation of Y731 at VEC with minor effects on Y685 and Y658. Thereby, BUT engages FFAR3, FFAR2, and c-Src kinase to induce phosphorylation of VEC. VEC phosphorylation correlated with enhanced endothelial permeability and c-Src-dependent remodeling of junctional VEC. Our data suggest that BUT, an SCFA and gut microbiota-derived metabolite, impacts vascular integrity by targeting VEC phosphorylation with potential impact on the pathophysiology and therapy of vascular diseases.

Disturbance of lipid metabolism in germ-free mice transplanted with gut microbiota of DSS-induced colitis mice.

Hepatobiliary abnormality and metabolic disorders are frequently observed complications in patients with inflammatory bowel diseases (IBD). Given that microbiota dysbiosis is a common pathophysiological feature of both IBD and metabolic diseases, we examined how the IBD-induced dysbiosis affects the host metabolism and contributes to the development of associated metabolic diseases using germ-free (GF) mice transplanted with fecal microbiota of DSS-induced colitis mice. There was no significant change in inflammation or barrier integrity in the gut of GF mice that received microbiota from colitis mice compared to their counterparts that were transplanted with microbiota from non-colitis healthy mice. Interestingly, it was observed that the GF recipients of colitis-induced altered microbiota showed a significant decrease in the weight of adipose tissues including mesenteric, epididymal, subcutaneous, and brown fat without any change in body weight, which was accompanied by abnormalities in adipose tissue functions such as fat storage and adiponectin production. Transplantation of colitis-induced altered microbiota also disrupted hepatic lipid metabolism in the GF recipient mice, which was observed by increases in synthesis and accumulation of cholesterol and bile acids in hepatocytes and a decrease in plasma HDL-cholesterol. Additional observations including elevated plasma levels of insulin, decreased hepatic production of FGF21, and decreased levels of fecal short chain fatty acids (SCFAs) and hepatic expression of SCFA receptors led to a conclusion that the transplantation of the colitis-associated dysbiotic microbiota was causally associated with impairments of insulin action and FGF21-adiponectin axis, possibly due to the low SCFA-producing capacity of the colonized microbiota, leading to metabolic abnormalities including adipose tissue dysfunction and dysregulated hepatic lipid metabolism. Our findings suggest potential mechanisms that explain how colitis-associated gut dysbiosis may contribute to the development of metabolic dysfunctions, which could be applied to clinical practice to improve the efficacy of treatment of IBD patients with comorbid metabolic disorders or vice versa.

Resveratrol Butyrate Ester Supplementation Blunts the Development of Offspring Hypertension in a Maternal Di-2-ethylhexyl Phthalate Exposure Rat Model.

Resveratrol (REV) is a plant polyphenol with a plethora of beneficial properties. We previously enhanced the efficacy of REV via esterification of REV with butyrate to form resveratrol butyrate ester (RBE). Compared with REV, RBE exhibits higher bioavailability and better antioxidant effects. Hypertension can originate in early life because of maternal toxic chemical exposure. This study aims to examine the effectiveness of RBE in the protection of offspring hypertension induced by maternal di-2-ethylhexylphthalate (DEHP) exposure and to explore the underlying mechanisms. DEHP (10 mg/kg/day) was used as oral gavage to pregnant rats during gestation and lactation. The control group received the vehicle. Three groups of DEHP-exposed dams received REV (6.67 mg/kg/day), or low-dose (3.33 mg/kg/day) or high-dose (6.67 mg/kg/day) RBE in drinking water during gestation and lactation. Perinatal DEHP exposure resulted in hypertension and bodyweight gain in adult male offspring, which was prevented by high-dose RBE. REV supplementation attenuated DEHP exposure-induced increases in blood pressure but not bodyweight. High-dose RBE decreased renal oxidative damage, increased plasma butyrate concentrations, and altered short chain fatty acid receptor (SCFA) expression. Low-dose RBE treatment reduced downstream mediators of the acryl hydrocarbon receptor (AHR) signaling pathway. Moreover, DEHP exposure, REV and RBE treatment differentially shaped the offspring's gut microbiota. In particular, high-dose RBE increased the abundance of the genus Duncaniella. The beneficial effects of RBE treatment were related to reducing oxidative damage, increasing plasma butyrate concentrations, downregulating SCFA receptor expression, antagonizing AHR signaling, and altering the gut microbiota. This study provides the first evidence of RBE as a novel plant polyphenol bioproduct targeting the oxidative stress and gut microbiota to protect against maternal DEHP exposure-primed offspring hypertension.

Virus induced dysbiosis promotes type 1 diabetes onset.

Autoimmune disorders are complex diseases of unclear etiology, although evidence suggests that the convergence of genetic susceptibility and environmental factors are critical. In type 1 diabetes (T1D), enterovirus infection and disruption of the intestinal microbiota are two environmental factors that have been independently associated with T1D onset in both humans and animal models. However, the possible interaction between viral infection and the intestinal microbiota remains unknown. Here, we demonstrate that Coxsackievirus B4 (CVB4), an enterovirus that accelerates T1D onset in non-obese diabetic (NOD) mice, induced restructuring of the intestinal microbiome prior to T1D onset. Microbiome restructuring was associated with an eroded mucosal barrier, bacterial translocation to the pancreatic lymph node, and increased circulating and intestinal commensal-reactive antibodies. The CVB4-induced change in community composition was strikingly similar to that of uninfected NOD mice that spontaneously developed diabetes, implying a mutual "diabetogenic" microbiome. Notably, members of the Bifidobacteria and Akkermansia genera emerged as conspicuous members of this diabetogenic microbiome, implicating these taxa, among others, in diabetes onset. Further, fecal microbiome transfer (FMT) of the diabetogenic microbiota from CVB4-infected mice enhanced T1D susceptibility and led to diminished expression of the short chain fatty acid receptor GPR43 and fewer IL-10-expressing regulatory CD4+ T cells in the intestine of naïve NOD recipients. These findings support an overlap in known environmental risk factors of T1D, and suggest that microbiome disruption and impaired intestinal homeostasis contribute to CVB-enhanced autoreactivity and T1D.

APSH-OP-6: ASSOCIATION BETWEEN THE GUT MICROBIOME AND THEIR METABOLITES WITH HUMAN BLOOD PRESSURE VARIABILITY

Objective: Blood pressure (BP) variability is an independent risk factor for cardiovascular events. Recent evidence supports a role for the gut microbiota in BP regulation. However, whether the gut microbiome is associated with BP variability is yet to be determined. Here, we aimed to investigate the interplay between the gut microbiome and their metabolites in relation to three separate parameters of BP variability. Design and method: Ambulatory BP monitoring was performed in 69 participants from two independent sites in Australia (55.1% women; mean ± SD 59.8 ± 7.26-years old, BMI 25.2 ± 2.83 kg/m2). This data was used to determine night-time dipping, morning BP surge (MBPS) and BP variability as standard deviation (SD). The gut microbiome was determined by 16S rRNA sequencing, mRNA expression levels of short-chain fatty acid (SCFA) receptors (FFAR2, FFAR3 and HCAR2) by real-time PCR (qPCR) and metabolite levels by gas chromatography. Results: We identified specific taxa associated with systolic BP variability, night-time dipping and MBPS. Notably, Alistipesfinegoldii and Lactobacillus spp. were only present in participants within the normal ranges of BP variability, MBPS and night-time dipping, while Prevotella spp. and Clostridium spp. were found to be present in extreme dippers and the highest quartiles of BP SD and MBPS. There was a negative association between MBPS and microbial alpha diversity (r = -0.244, P = 0.046). MBPS was also negatively associated with plasma levels of microbial metabolites (SCFAs) (r = -0.305, P = 0.020), particularly acetate (r = -0.311, P = 0.017). We identified a negative correlation between SD data and SCFA receptor FFAR2 mRNA, indicating that participants with higher BP SD had overall lower expression levels of FFAR2 (SD day: r = -0.31, P = 0.039; SD night: r = -0.36, P = 0.016; SD total: r = -0.32, P = 0.035). We also found that participants with a greater percentage in night-time dipping had higher levels of FFAR2 (r = 0.38, P = 0.0087). Conclusions: Gut microbiome diversity, levels of microbial metabolites, and the bacteria Alistipesfinegoldii and Lactobacillus were associated with lower BP variability, whereas a blunted level of SCFA receptor FFAR2 mRNA and Clostridium and Prevotella bacteria were associated with higher BP variability. Our findings suggest the gut microbiome and metabolites may be involved in the regulation of BP variability.

Analysis of microbiota-host communication mediated by butyrate in Atlantic salmon

Butyrate is a microbiota-produced metabolite, sensed by host short-chain fatty acid receptors FFAR2 (Gpr43), FFAR3 (Gpr41), HCAR2 (Gpr109A), and Histone deacetylase (HDAC) that promotes microbiota-host crosstalk. Butyrate influences energy uptake, developmental and immune response in mammals. This microbial metabolite is produced by around 79 anaerobic genera present in the mammalian gut, yet little is known about the role of butyrate in the host-microbiota interaction in salmonid fish. To further our knowledge of this interaction, we analyzed the intestinal microbiota and genome of Atlantic salmon (Salmo salar), searching for butyrate-producing genera and host butyrate receptors. We identified Firmicutes, Proteobacteria, and Actinobacteria as the main butyrate-producing bacteria in the salmon gut microbiota. In the Atlantic salmon genome, we identified an expansion of genes orthologous to FFAR2 and HCAR2 receptors, and class I and IIa HDACs that are sensitive to butyrate. In addition, we determined the expression levels of orthologous of HCAR2 in the gut, spleen, and head-kidney, and FFAR2 in RTgutGC cells. The effect of butyrate on the Atlantic salmon immune response was evaluated by analyzing the pro and anti-inflammatory cytokines response in vitro in SHK-1 cells by RT-qPCR. Butyrate decreased the expression of the pro-inflammatory cytokine IL-1β and increased anti-inflammatory IL-10 and TGF-β cytokines. Butyrate also reduced the expression of interferon-alpha, Mx, and PKR, and decreased the viral load at a higher concentration (4 mM) in cells treated with this molecule before the infection with Infectious Pancreatic Necrosis Virus (IPNV) by mechanisms independent of FFAR2, FFAR3 and HCAR2 expression that probably inhibit HDAC. Moreover, butyrate modified phosphorylation of cytoplasmic proteins in RTgutGC cells. Our data allow us to infer that Atlantic salmon have the ability to sense butyrate produced by their gut microbiota via different specific targets, through which butyrate modulates the immune response of pro and anti-inflammatory cytokines and the antiviral response.

Acetate suppresses myocardial contraction via the short-chain fatty acid receptor GPR43.

The heart has high energy requirements, with an estimated 40%-60% of myocardial ATP production derived from the oxidation of fatty acids under physiological conditions. However, the effect of short-chain fatty acids on myocardial contraction remains controversial, warranting further research. The present study sought to investigate the effects and mechanisms of acetate, a short-chain fatty acid, on myocardial contraction in rat ventricular myocytes. Echocardiography and Langendorff heart perfusion were used to evaluate cardiac function. Cell shortening and calcium transient were measured in isolated cardiomyocytes. The patch-clamp method determined the action potential and L-type Ca2+ current in cardiomyocytes. Moreover, the expression of GPR43, a type of short-chain fatty acid receptors in cardiomyocytes was examined by immunofluorescent staining and Western blot. We demonstrated that acetate transiently reduced left ventricular developmental pressure in isolated Langendorff heart perfusion model, with no effect on stroke volume and cardiac output in vivo. In addition, acetate transiently and reversibly inhibited cardiomyocyte contraction and calcium transient. Acetate did not affect the action potential and L-type Ca2+ currents in cardiomyocytes. As a short-chain fatty acid receptor, GPR43 was expressed in rat cardiomyocytes. Furthermore, the GPR43 antagonist GLPG0974 prevented the acetate-induced inhibitory effect on myocardial contraction. We conclude that acetate transiently inhibits contraction via the short-chain fatty acid receptor GPR43 in cardiomyocytes.

Foods may modify responsiveness to cancer immune checkpoint blockers by altering both the gut microbiota and activation of estrogen receptors in immune cells

Estrogen receptor alpha positive (ERα+) breast cancers are refractory to immune checkpoint blocker (ICB) monotherapy, while ICBs are part of a standard of care for triple negative breast cancers (TNBCs). Besides tumor ERα expression, another difference between the two types of breast cancers is that only ERα+ patients exhibit elevated tumor estradiol (E2) levels, compared with surrounding normal tissue. Recent evidence suggests that inhibition of ERα or activation of ERβ or G protein-coupled estrogen receptor (GPER) in immune cells in the tumor microenvironment (TME) increases tumor CD8+ T cell infiltration and boosts cancer ICB response. Ovarian and adipose-produced estrogens activate all three ERs equally, but plant estrogens (phytochemicals) preferentially activate ERβ or GPER. The gut microbiota is a key player in determining response to ICBs, and high abundance of Firmicutes and high fecal levels of short chain fatty acids (SCFAs) that are mainly produced by Firmicutes, are linked to improved effectiveness of ICB therapy. Interestingly, the gut microbiota of ERα+ breast cancer patients contain significantly lower abundance of Firmicutes species than the gut microbiota of TNBC patients. Many factors modify the gut microbiota, especially diet. The gut microbiota altering diets include (i) foods high in ERβ and GPER activating plant phytochemicals or (ii) SCFAs producing fiber that also reduces circulating estrogen levels, (iii) estrogen levels reducing fasting/caloric restriction, or (iv) ketogenic diet which reduces fecal SCFA levels but increases hepatic production of SCFA receptor activating ketone bodies. It is thus possible that certain foods or dietary patterns can modify both the gut microbiota and activation of the estrogen receptors in the tumor immune cells, and consequently regulate the effectiveness of ICB therapy against cancers.

Reducing light exposure enhances the circadian rhythm of the biological clock through interactions with the gut microbiota

Light mainly synergistically regulates the central biological clock system. In farming, long-term light exposure may induce metabolic disorders and increase the load on the liver in laying hens. In contrast, intermittent photoperiods can reduce light exposure and increase rest time to improve the health of laying hens. The circadian rhythms of gut microbes are essential for the health of the host. However, the circadian rhythms of gut microbes and how those microbes interact with the host under intermittent photoperiods are not clear. We used laying hens as a model to evaluate the circadian rhythms of gut microbes and biological clock genes under different intermittent photoperiods. Intermittent photoperiod 1 (IP1, 16 [3 h -L/1 h -D]: 8 D) enhanced the circadian rhythms of cBmal1, cBmal2, cCry1, and cCry2 in the hypothalamus and increased the expression of cClock, cBmal1, and cCry2 in the liver and seven clock genes in the cecal wall. The intermittent photoperiod also significantly altered the composition and metabolic function of the cecal microbiota via the melatonin pathway. The concentrations of short-chain fatty acids (SCFAs) and the abundance of SCFA-producing genera such as Odoribacter significantly increased under the IP1 treatment and might have further fed back into and strengthened the peripheral and central rhythms by activating the SCFA receptor gene pathway in cecal wall. These findings clarify the mediation mechanisms for the circadian rhythms of the central circadian clock and highlight the role of intermittent photoperiod-induced regulation of the interaction between the host clock and the cecal microbial community.

The Cognitive Improvement and Alleviation of Brain Hypermetabolism Caused by FFAR3 Ablation in Tg2576 Mice Is Persistent under Diet-Induced Obesity.

Obesity and aging are becoming increasingly prevalent across the globe. It has been established that aging is the major risk factor for Alzheimer's disease (AD), and it is becoming increasingly evident that obesity and the associated insulin resistance are also notably relevant risk factors. The biological plausibility of the link between high adiposity, insulin resistance, and dementia is central for understanding AD etiology, and to form bases for prevention efforts to decrease the disease burden. Several studies have demonstrated a strong association between short chain fatty acid receptor FFAR3 and insulin sensitivity. Interestingly, it has been recently established that FFAR3 mRNA levels are increased in early stages of the AD pathology, indicating that FFAR3 could play a key role in AD onset and progression. Indeed, in the present study we demonstrate that the ablation of the Ffar3 gene in Tg2576 mice prevents the development of cognitive deficiencies in advanced stages of the disease. Notably, this cognitive improvement is also maintained upon a severe metabolic challenge such as the exposure to high-fat diet (HFD) feeding. Moreover, FFAR3 deletion restores the brain hypermetabolism displayed by Tg2576 mice. Collectively, these data postulate FFAR3 as a potential novel target for AD.

OR15-3 Contribution of Hyperandrogenemia to Dysbiosis, Gut Inflammation, and Dysregulation of Short-Chain Fatty Acid Homeostasis in Mouse Model of Polycystic Ovary Syndrome

Abstract Introduction and Purpose Polycystic Ovary Syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Notably, PCOS women with hyperandrogenism have a pronounced increased risk for cardio-metabolic comorbidities. The gut microbiome is responsible for fermentation of indigestible fiber to produce short-chain fatty acids (SCFA), which help maintain metabolic function and reduce gut inflammation. Alteration in the gut microbiome, or dysbiosis, affects overall metabolic homeostasis and contributes to pathogenesis of metabolic diseases. While dysbiosis has been observed in women with PCOS, the molecular mechanisms of hyperandrogenemia-induced dysbiosis and its contribution to SCFA excretion and gut inflammation have not been studied in PCOS. Methods Four-week old C57BL/6N female mice were implanted subcutaneously with dihydrotestosterone (DHT, 8.0 mg) or vehicle silastic tubes (n=8/grp). Animals were treated day 90 and the gastrointestinal tract was collected. Expression levels of mRNA were assessed by RT-qPCR. Fecal microbiota was assessed by 16S rRNA gene sequencing and profiled using MicrobiomeAnalyst; SCFA concentrations were assessed by LC-MS. Results DHT-treated female mice had significantly increased lean mass (21.35 ± 0.84 vs 19.25 ± 0.55 g, p&amp;lt;0.05) and increased fat mass (5.18 ± 1.45 vs 2.73 ± 0.64 g, p&amp;lt;0.05) compared to the vehicle counterparts. DHT-treated female mice showed increased HbA1C (5.18 ± 1.45 vs 2.73 ± 0.64%, p&amp;lt;0.05). Hyperandrogenemic females showed altered gastrointestinal morphology, having decreased small intestine (33.03±2.05 vs 28.69±2.604 cm, p&amp;lt;0.05) and colon length (7.88 ± 0.64 vs 6.60 ± 0.55 cm, p&amp;lt;0.05) as well as increased immune cell infiltration assessed by histology. DHT-treated female mice have an increase in the relative percent abundance of Proteobacteria (2.04 ± 0.62 vs 0.35 ± 0.23%, p&amp;lt;0.05) and in the ratio of Firmicutes/Bacteriodetes (1.92 ± 0.47 vs 1.11 ± 0.17, p&amp;lt;0.05). Fecal concentrations of short-chain fatty acids were higher in DHT-females for butyric acid (92.33 vs 404.8 ng/mg feces, p&amp;lt;0.05), acetic acid (571.8 vs 1592 ng/mg feces, p&amp;lt;0.05), and propionic acid (80.59 vs 167.3 ng/mg feces, p&amp;lt;0.05). However, expression of the SCFA receptor Ffar2 in the colon was upregulated by DHT (1.31 ± 0.15-fold, p&amp;lt;0.05), indicating the possibility of a compensation to ameliorate increased SCFA excretion. The mRNA expression of lipopolysaccharide induced inflammation markers were significantly upregulated by DHT in the proximal colon (Litaf, 1.69 ± 0.29-fold; Tlr4 1.27 ± 0.15-fold, p&amp;lt;0.05) compared with vehicles. Conclusions Androgen-mediated gut dysbiosis may contribute to altered glucose handling, adiposity, and metabolic homeostasis in PCOS. Increased elimination of SCFA in DHT-treated female mice may indicate less efficient absorption, which can contribute to colonic inflammation, altered gastrointestinal morphology, and increased gut permeability. Together, our results highlight the potential role of androgen-mediated gut dysbiosis to influence metabolic dysfunction. Presentation: Sunday, June 12, 2022 11:30 a.m. - 11:45 a.m.

Co-Cultures of Lactobacillus acidophilus and Bacillus subtilis Enhance Mucosal Barrier by Modulating Gut Microbiota-Derived Short-Chain Fatty Acids.

Weaning stress induces intestinal barrier dysfunction and immune dysregulation in mammals. Various interventions based on the modulation of intestinal microbiota have been proposed. Our study aims to explore the effects of co-cultures from Lactobacillus acidophilus and Bacillus subtilis (FAM®) on intestinal mucosal barrier from the perspective of metabolic function of gut microbiota. A total of 180 piglets were allocated to three groups, i.e., a control group (C, basal diet), a FAM group (F, basal diet supplemented with 0.1% FAM), and an antibiotic group (A, basal diet supplemented with antibiotic mixtures). Here, we showed FAM supplementation significantly increased body weight and reduced diarrhea incidence, accompanied by attenuated mucosal damage, increased levels of tight junction proteins, serum diamine oxidase (DAO) and antimicrobial peptides. In addition, 16S rRNA sequencing and metabolomic analysis revealed an increase in relative abundance of Clostridiales, Ruminococcaceae, Firmicutes and Muribaculaceae and a significant increase in the total short-chain fatty acids (SCFAs) and butyric acid in FAM-treated piglets. FAM also increased CD4+ T cells and SIgA+ cells in intestinal mucosa and SIgA production in colon contents. Furthermore, FAM upregulated the expression of IL-22, short-chain fatty acid receptors GPR43 and GPR41, aryl hydrocarbon receptor (AhR), and hypoxia-inducible factor 1α (HIF-1α). FAM shows great application prospect in gut health and provides a reference for infant weaning.

Altered Nasal Microbiome in Atrophic Rhinitis: A Novel Theory of Etiopathogenesis and Therapy.

Atrophic rhinitis (AtR) is a chronic nasal condition with polygenic and polybacterial etiology. We investigated the clinical outcomes of honey therapy and the associated nasal microbiome in AtR. For eight weeks, a nonrandomized control trial using a nasal spray of 10% manuka honey and saline on the right and left sides of the nose was conducted on 19 primary AtR patients. A nasal endoscopy was performed and a mucosal biopsy were taken before and after the intervention. Five of the nineteen patients were selected for microbiome and GPR43 expression studies. We used manuka honey to describe an effective prebiotic treatment for atrophic rhinitis. There were nine males and ten females with an average (±SD) age of 33.8 (±10.7) years. Endoscopic scores and clinical symptoms improved in honey-treated nasal cavities (p &lt; 0.003). There was a significant decrease in inflammation, restoration of mucus glands, and increased expression of GPR43 in the nasal cavities with honey therapy. The nasal microbiome composition before and after treatment was documented. Particularly, short chain fatty acid (SCFA) producers were positively enriched after honey therapy and correlated with improved clinical outcomes like nasal crusting, congestion, and discharge. Our approach to treating AtR patients with manuka honey illustrated effective clinical outcomes such as (1) decreased fetid smell, (2) thickening of the mucosa, (3) decreased inflammation with healed mucosal ulcers, (4) increased concentration of the mucosal glands, (5) altered nasal microbiome, and (6) increased expression of SCFA receptors. These changes are consequent to resetting the nasal microbiome due to honey therapy.

Protection by -Biotics against Hypertension Programmed by Maternal High Fructose Diet: Rectification of Dysregulated Expression of Short-Chain Fatty Acid Receptors in the Hypothalamic Paraventricular Nucleus of Adult Offspring.

The role of short-chain fatty acids (SCFAs) in the brain on the developmental programming of hypertension is poorly understood. The present study explored dysregulated tissue levels of SCFAs and expression of SCFA-sensing receptors in the hypothalamic paraventricular nucleus (PVN), a key forebrain region engaged in neural regulation of blood pressure of offspring to maternal high fructose diet (HFD) exposure. We further investigated the engagement of SCFA-sensing receptors in PVN in the beneficial effects of -biotics (prebiotic, probiotic, synbiotic, and postbiotic) on programmed hypertension. Maternal HFD during gestation and lactation significantly reduced circulating butyrate, along with decreased tissue level of butyrate and increased expression of SCFA-sensing receptors, GPR41 and olfr78, and tissue oxidative stress and neuroinflammation in PVN of HFD offspring that were rectified by oral supplement with -biotics. Gene silencing of GPR41 or olfr78 mRNA in PVN also protected adult HFD offspring from programmed hypertension and alleviated the induced oxidative stress and inflammation in PVN. In addition, oral supplement with postbiotic butyrate restored tissue butyrate levels, rectified expressions of GPR41 and olfr78 in PVN, and protected against programmed hypertension in adult HFD offspring. These data suggest that alterations in tissue butyrate level, expression of GPR41 and olfr78, and activation of SCFA-sensing receptor-dependent tissue oxidative stress and neuroinflammation in PVN could be novel mechanisms that underlie hypertension programmed by maternal HFD exposure in adult offspring. Furthermore, oral -biotics supplementation may exert beneficial effects on hypertension of developmental origin by targeting dysfunctional SCFA-sensing receptors in PVN to exert antioxidant and anti-inflammatory actions in the brain.

Role of brain-gut-muscle axis in human health and energy homeostasis.

The interrelationship between brain, gut and skeletal muscle plays a key role in energy homeostasis of the body, and is becoming a hot topic of research. Intestinal microbial metabolites, such as short-chain fatty acids (SCFAs), bile acids (BAs) and tryptophan metabolites, communicate with the central nervous system (CNS) by binding to their receptors. In fact, there is a cross-talk between the CNS and the gut. The CNS, under the stimulation of pressure, will also affect the stability of the intestinal system, including the local intestinal transport, secretion and permeability of the intestinal system. After the gastrointestinal tract collects information about food absorption, it sends signals to the central system through vagus nerve and other channels to stimulate the secretion of brain-gut peptide and produce feeding behavior, which is also an important part of maintaining energy homeostasis. Skeletal muscle has receptors for SCFAs and BAs. Therefore, intestinal microbiota can participate in skeletal muscle energy metabolism and muscle fiber conversion through their metabolites. Skeletal muscles can also communicate with the gut system during exercise. Under the stimulation of exercise, myokines secreted by skeletal muscle causes the secretion of intestinal hormones, and these hormones can act on the central system and affect food intake. The idea of the brain-gut-muscle axis is gradually being confirmed, and at present it is important for regulating energy homeostasis, which also seems to be relevant to human health. This article focuses on the interaction of intestinal microbiota, central nervous, skeletal muscle energy metabolism, and feeding behavior regulation, which will provide new insight into the diagnostic and treatment strategies for obesity, diabetes, and other metabolic diseases.

Effects of long-term administration of theasinensin A on healthy C57BL/6J mice: Enhancing the function of epididymal white adipose tissue and regulating the colonic microenvironment

The effects of theasinensin A (TSA) on healthy C57BL/6J mice were investigated. Results showed that long-term administration of 100 mg/kg body weight/day TSA might be non-toxic to healthy mice based on the unaltered basal biochemical indicators related to glucose and lipid metabolism, inflammatory factors and hepatic injury. On the contrary, TSA stimulated the rate of lipid turnover and browning of white adipose tissues, accelerated the adipocytic energy mobilization, and then reduced the white adipocytic size, ultimately enhancing resistance to obesity in healthy mice. Furthermore, TSA not only up-regulated the expression of mucin, tight junction protein, and short-chain fatty acids receptor, but also regulated the intestinal microbiota by enhancing the typical beneficial microbe Akkermansia muciniphila, thereby modulating the colonic microenvironment. These results suggested that TSA had a potential strengthening effect on the resistance of healthy mice to metabolic disorders, which provides a theoretical basis for the utilization of TSA.