Short-Chain Fatty Acid Receptors and Cardiovascular Function

A disturbed metabolite-GPCR axis is associated with microbial dysbiosis in IBD patients: Potential role of GPR109A in macrophages

Inflammatory Bowel Disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract characterized by disrupted immune function. Indeed, gut microbiota dysbiosis and metabolomic profile alterations, are hallmarks of IBD. In this scenario, metabolite-sensing G-protein coupled receptors (GPCRs), involved in several biological processes, have emerged as pivotal players in the pathophysiology of IBD. The aim of this study was to characterize the axis microbiota-metabolite-GPCR in intestinal surgical resections from IBD patients. Results showed that UC patients had a lower microbiota richness and bacterial load, with a higher proportion of the genus Cellulosimicrobium and a reduced proportion of Escherichia, whereas CD patients showed a decreased abundance of Enterococcus. Furthermore, metabolomic analysis revealed alterations in carboxylic acids, fatty acids, and amino acids in UC and CD samples. These patients also exhibited upregulated expression of most metabolite-sensing GPCRs analysed, which positively correlated with pro-inflammatory and pro-fibrotic markers. The role of GPR109A was studied in depth and increased expression of this receptor was detected in epithelial cells and cells from lamina propria, including CD68+ macrophages, in IBD patients. The treatment with β-hydroxybutyrate increased gene expression of GPR109A, CD86, IL1B and NOS2 in U937-derived macrophages. Besides, when GPR109A was transiently silenced, the mRNA expression and secretion of IL-1β, IL-6 and TNF-α were impaired in M1 macrophages. Finally, the secretome from siGPR109A M1 macrophages reduced the gene and protein expression of COL1A1 and COL3A1 in intestinal fibroblasts. A better understanding of metabolite-sensing GPCRs, such as GPR109A, could establish their potential as therapeutic targets for managing IBD.

Traditional Chinese medicine improved diabetic kidney disease through targeting gut microbiota

CONTEXT

Diabetic kidney disease (DKD) affects nearly 40% of diabetic patients, often leading to end-stage renal disease that requires renal replacement therapies, such as dialysis and transplantation. The gut microbiota, an integral aspect of human evolution, plays a crucial role in this condition. Traditional Chinese medicine (TCM) has shown promising outcomes in ameliorating DKD by addressing the gut microbiota.

OBJECTIVE

This review elucidates the modifications in gut microbiota observed in DKD and explores the impact of TCM interventions on correcting microbial dysregulation.

METHODS

We searched relevant articles from databases including Web of Science, PubMed, ScienceDirect, Wiley, and Springer Nature. The following keywords were used: diabetic kidney disease, diabetic nephropathy, gut microbiota, natural product, TCM, Chinese herbal medicine, and Chinese medicinal herbs. Rigorous criteria were applied to identify high-quality studies on TCM interventions against DKD.

RESULTS

Dysregulation of the gut microbiota, including Lactobacillus, Streptococcus, and Clostridium, has been observed in individuals with DKD. Key indicators of microbial dysregulation include increased uremic solutes and decreased short-chain fatty acids. Various TCM therapies, such as formulas, tablets, granules, capsules, and decoctions, exhibit unique advantages in regulating the disordered microbiota to treat DKD.

CONCLUSION

This review highlights the importance of targeting the gut-kidney axis to regulate microbial disorders, their metabolites, and associated signaling pathways in DKD. The Qing-Re-Xiao-Zheng formula, the Shenyan Kangfu tablet, the Huangkui capsule, and the Bekhogainsam decoction are potential candidates to address the gut-kidney axis. TCM interventions offer a significant therapeutic approach by targeting microbial dysregulation in patients with DKD.

The dynamic crosslinking between gut microbiota and inflammation during aging: reviewing the nutritional and hormetic approaches against dysbiosis and inflammaging

The early-life gut microbiota (GM) is increasingly recognized for its contributions to human health and disease over time. Microbiota composition, influenced by factors like race, geography, lifestyle, and individual differences, is subject to change. The GM serves dual roles, defending against pathogens and shaping the host immune system. Disruptions in microbial composition can lead to immune dysregulation, impacting defense mechanisms. Additionally, GM aids digestion, releasing nutrients and influencing physiological systems like the liver, brain, and endocrine system through microbial metabolites. Dysbiosis disrupts intestinal homeostasis, contributing to age-related diseases. Recent studies are elucidating the bacterial species that characterize a healthy microbiota, defining what constitutes a 'healthy' colonic microbiota. The present review article focuses on the importance of microbiome composition for the development of homeostasis and the roles of GM during aging and the age-related diseases caused by the alteration in gut microbial communities. This article might also help the readers to find treatments targeting GM for the prevention of various diseases linked to it effectively.

Low-Molecular-Weight Compounds Produced by the Intestinal Microbiota and Cardiovascular Disease

Cardiovascular disease is the main cause of mortality in industrialized countries, with over 500 million people affected worldwide. In this work, the roles of low-molecular-weight metabolites originating from the gut microbiome, such as short-chain fatty acids, hydrogen sulfide, trimethylamine, phenylacetic acid, secondary bile acids, indoles, different gases, neurotransmitters, vitamins, and complex lipids, are discussed in relation to their CVD-promoting or preventing activities. Molecules of mixed microbial and human hepatic origin, such as trimethylamine N-oxide and phenylacetylglutamine, are also presented. Finally, dietary agents with cardioprotective effects, such as probiotics, prebiotics, mono- and poly-unsaturated fatty acids, carotenoids, and polyphenols, are also discussed. A special emphasis is given to their gut microbiota-modulating properties.

Cronobacter sakazakii induced sepsis-associated arrhythmias through its outer membrane vesicles

Sepsis-induced arrhythmia, linked to sudden cardiac death, is associated with gut microbiota, though the exact relationship is unclear. This study aimed to elucidate the relationship between Cronobacter sakazakii (C. sakazakii) and arrhythmia. The relative abundance of C. sakazakii was increased in cecal ligation and puncture (CLP)-induced septic mice. Live C. sakazakii, supernatant, and outer membrane vesicles (OMVs) resulted in premature ventricular beat (PVB), sinus arrhythmia (SA), and increased arrhythmia and mortality in sepsis model through dysregulated ion channel proteins. Moreover, short-chain fatty acids (SCFAs) showed antibacterial effects in vitro. We confirmed sodium acetate (C2) and sodium butyrate (C4) protect from C. sakazakii-induced arrhythmia, and C2 and C4 protected from septic arrhythmia by activating free fatty acid receptor 2 and 3 (FFAR2 and FFAR3) in mice. These findings point to how C. sakazakii's OMVs trigger arrhythmia, and SCFAs may be a treatment for septic arrhythmia.

Microbiota alterations associated with vascular diseases: postbiotics as a next-generation magic bullet for gut-vascular axis

The intestinal microbiota represents a key element in maintaining the homeostasis and health conditions of the host. Vascular pathologies and other risk factors such as aging have been recently associated with dysbiosis. The qualitative and quantitative alteration of the intestinal microbiota hinders correct metabolic homeostasis, causing structural and functional changes of the intestinal wall itself. Impairment of the intestinal microbiota, combined with the reduction of the barrier function, worsen the pathological scenarios of peripheral tissues over time, including the vascular one. Several experimental evidence, collected in this review, describes in detail the changes of the intestinal microbiota in dysbiosis associated with vascular alterations, such as atherosclerosis, hypertension, and endothelial dysfunction, the resulting metabolic disorders and how these can impact on vascular health. In this context, the gut-vascular axis is considered, for the first time, as a merged unit involved in the development and progression of vascular pathologies and as a promising target. Current approaches for the management of dysbiosis such as probiotics, prebiotics and dietary modifications act mainly on the intestinal district. Postbiotics, described as preparation of inanimate microorganisms and/or their components that confers health benefits on the host, represent an innovative strategy for a dual management of intestinal dysbiosis and vascular pathologies. In this context, this review has the further purpose of defining the positive effects of the supplementation of bacterial strains metabolites (short‑chain fatty acids, exopolysaccharides, lipoteichoic acids, gallic acid, and protocatechuic acid) restoring intestinal homeostasis and acting directly on the vascular district through the gut-vascular axis.

Pathophysiological relevance and therapeutic outlook of GPR43 in atherosclerosis

Atherosclerosis (AS) is an inflammatory arterial disorder that occurs due to the deposition of the excessive lipoprotein under the artery intima, mainly including low-density lipoprotein and other apolipoprotein B-containing lipoproteins. G protein-coupled receptors (GPCRs) play a crucial role in transmitting signals in physiological and pathophysiological conditions. GPCRs recognize inflammatory mediators, thereby serving as important players during chronic inflammatory processes. It has been demonstrated that free fatty acids can function as ligands for various GPCRs, such as free fatty acid receptor (FFAR)1/GPR40, FFAR2/GPR43, FFAR3/GPR41, FFAR4/GPR120, and the lipid metabolite binding glucose-dependent insulinotropic receptor (GPR119). This review discusses GPR43 and its ligands in the pathogenesis of AS, especially focusing on its distinct role in regulating chronic vascular inflammation, inhibiting oxidative stress, ameliorating endothelial dysfunction and improving dyslipidemia. It is hoped that this review may provide guidance for further studies aimed at GPR43 as a promising target for drug development in the prevention and therapy of AS.

Dietary Fiber-Derived Microbial Butyrate Suppresses ILC2-Dependent Airway Inflammation in COPD

Group 2 innate lymphoid cells (ILC2) strongly modulate COPD pathogenesis. However, the significance of microbiota in ILC2s remains unelucidated. Herein, we investigated the immunomodulatory role of short-chain fatty acids (SCFAs) in regulating ILC2-associated airway inflammation and explores its associated mechanism in COPD. In particular, we assessed the SCFA-mediated regulation of survival, proliferation, and cytokine production in lung sorted ILC2s. To elucidate butyrate action in ILC2-driven inflammatory response in COPD models, we administered butyrate to BALB/c mice via drinking water. We revealed that SCFAs, especially butyrate, derived from dietary fiber fermentation by gut microbiota inhibited pulmonary ILC2 functions and suppressed both IL-13 and IL-5 synthesis by murine ILC2s. Using in vivo and in vitro experimentation, we validated that butyrate significantly ameliorated ILC2-induced inflammation. We further demonstrated that butyrate suppressed ILC2 proliferation and GATA3 expression. Additionally, butyrate potentially utilized histone deacetylase (HDAC) inhibition to enhance NFIL3 promoter acetylation, thereby augmenting its expression, which eventually inhibited cytokine production in ILC2s. Taken together, the aforementioned evidences demonstrated a previously unrecognized role of microbial-derived SCFAs on pulmonary ILC2s in COPD. Moreover, our evidences suggest that metabolomics and gut microbiota modulation may prevent lung inflammation of COPD.

Expression of free fatty acid receptor 2 in normal and neoplastic tissues

OBJECTIVE

Little information is available concerning protein expression of the free fatty acid receptor 2 (FFAR2), especially in tumours. Therefore, the aim of the present study was to comprehensively characterise the expression profile of FFAR2 in a large series of human normal and neoplastic tissues using immunohistochemistry thus providing a basis for further in-depth investigations into its potential diagnostic or therapeutic importance.

METHODS

We developed a novel rabbit polyclonal anti-FFAR2 antibody, 0524, directed against the C-terminal region of human FFAR2. Antibody specificity was confirmed via Western blot analyses and immunocytochemistry using the FFAR2-expressing cell line BON-1 and FFAR2-specific small interfering RNA as well as native and FFAR2-transfected HEK-293 cells. The antibody was then used for immunohistochemical analyses of various formalin-fixed, paraffin-embedded specimens of normal and neoplastic human tissues.

RESULTS

In normal tissues, FFAR2 was mainly present in distinct cell populations of the cerebral cortex, follicular cells and C cells of the thyroid, cardiomyocytes of the heart, bronchial epithelia and glands, hepatocytes and bile duct epithelia of the liver, gall bladder epithelium, exocrine and β-cells of the endocrine pancreas, glomerular mesangial cells and podocytes as well as collecting ducts of the kidney, intestinal mucosa (particularly enteroendocrine cells), prostate epithelium, seminiferous tubules of the testicles, and placental syncytiotrophoblasts. In neoplastic tissues, FFAR2 was particularly prevalent in papillary thyroid carcinomas, parathyroid adenomas, and gastric, colon, pancreatic, hepatocellular, cholangiocellular, urinary bladder, breast, cervical, and ovarian carcinomas.

CONCLUSIONS

We generated and characterised a novel rabbit polyclonal anti-human FFAR2 antibody that is well-suited for visualising FFAR2 expression in human routine pathology tissues. This antibody is also suitable for Western blot and immunocytochemistry experiments. To our knowledge, this antibody enabled the first broad FFAR2 protein expression profile in various normal and neoplastic human tissues.

Cardioprotective properties of OMT-28, a synthetic analog of omega-3 epoxyeicosanoids

OMT-28 is a metabolically robust small molecule developed to mimic the structure and function of omega-3 epoxyeicosanoids. However, it remained unknown to what extent OMT-28 also shares the cardioprotective and anti-inflammatory properties of its natural counterparts. To address this question, we analyzed the ability of OMT-28 to ameliorate hypoxia/reoxygenation (HR)-injury and lipopolysaccharide (LPS)-induced endotoxemia in cultured cardiomyocytes. Moreover, we investigated the potential of OMT-28 to limit functional damage and inflammasome activation in isolated perfused mouse hearts subjected to ischemia/reperfusion (IR) injury. In the HR model, OMT-28 (1 μM) treatment largely preserved cell viability (about 75 versus 40% with the vehicle) and mitochondrial function as indicated by the maintenance of NAD+/NADH-, ADP/ATP-, and respiratory control ratios. Moreover, OMT-28 blocked the HR-induced production of mitochondrial reactive oxygen species. Pharmacological inhibition experiments suggested that Gαi, PI3K, PPARα, and Sirt1 are essential components of the OMT-28-mediated pro-survival pathway. Counteracting inflammatory injury of cardiomyocytes, OMT-28 (1 μM) reduced LPS-induced increases in TNFα protein (by about 85% versus vehicle) and NF-κB DNA binding (by about 70% versus vehicle). In the ex vivo model, OMT-28 improved post-IR myocardial function recovery to reach about 40% of the baseline value compared to less than 20% with the vehicle. Furthermore, OMT-28 (1 μM) limited IR-induced NLRP3 inflammasome activation similarly to a direct NLRP3 inhibitor (MCC950). Overall, this study demonstrates that OMT-28 possesses potent cardio-protective and anti-inflammatory properties supporting the hypothesis that extending the bioavailability of omega-3 epoxyeicosanoids may improve their prospects as therapeutic agents.

Relationships between Habitual Polyphenol Consumption and Gut Microbiota in the INCLD Health Cohort

While polyphenol consumption is often associated with an increased abundance of beneficial microbes and decreased opportunistic pathogens, these relationships are not completely described for polyphenols consumed via habitual diet, including culinary herb and spice consumption. This analysis of the International Cohort on Lifestyle Determinants of Health (INCLD Health) cohort uses a dietary questionnaire and 16s microbiome data to examine relationships between habitual polyphenol consumption and gut microbiota in healthy adults (n = 96). In this exploratory analysis, microbial taxa, but not diversity measures, differed by levels of dietary polyphenol consumption. Taxa identified as exploratory biomarkers of daily polyphenol consumption (mg/day) included Lactobacillus, Bacteroides, Enterococcus, Eubacterium ventriosum group, Ruminococcus torques group, and Sutterella. Taxa identified as exploratory biomarkers of the frequency of polyphenol-weighted herb and spice use included Lachnospiraceae UCG-001, Lachnospiraceae UCG-004, Methanobrevibacter, Lachnoclostridium, and Lachnotalea. Several of the differentiating taxa carry out activities important for human health, although out of these taxa, those with previously described pro-inflammatory qualities in certain contexts displayed inverse relationships with polyphenol consumption. Our results suggest that higher quantities of habitual polyphenol consumption may support an intestinal environment where opportunistic and pro-inflammatory bacteria are represented in a lower relative abundance compared to those with less potentially virulent qualities.

Cellulase with Bacillus velezensis improves physicochemical characteristics, microbiota and metabolites of corn germ meal during two-stage co-fermentation

Corn germ meal (CGM) is one of the major byproducts of corn starch extraction. Although CGM has rich fiber content, it lacks good protein content and amino acid balance, and therefore cannot be fully utilized as animal feed. In this study, we investigated the processing effect of cellulase synergized with Bacillus velezensis on the nutritional value of pretreated CGM (PCGM) in two-stage solid-state fermentation (SSF). High-throughput sequencing technology was used to explore the dynamic changes in microbial diversity. The results showed that compared with four combinations of B. velezensis + Lactiplantibacillus plantarum (PCGM-BL), cellulase + L. plantarum (PCGM-CL),control group (PCGM-CK), and cellulase + B. velezensis + L. plantarum (PCGM-BCL), the fourth combination of PCGM-BCL significantly improved the nutritional characteristics of PCGM. After two-stage SSF (48 h), viable bacterial count and contents of crude protein (CP) and trichloroacetic acid-soluble protein (TCA-SP) all were increased in PCGM-BCL (p < 0.05), while the pH was reduced to 4.38 ± 0.02. In addition, compared with PCGM-BL, the cellulose degradation rate increased from 5.02 to 50.74%, increasing the amounts of short-chain fatty acids (216.61 ± 2.74 to 1727.55 ± 23.00 µg/g) and total amino acids (18.60 to 21.02%) in PCGM-BCL. Furthermore, high-throughput sequencing analysis revealed significant dynamic changes in microbial diversity. In the first stage of PCGM-BCL fermentation, Bacillus was the dominant genus (99.87%), which after 24 h of anaerobic fermentation changed to lactobacillus (37.45%). Kyoto Encylopaedia of Genes and Genomes (KEGG) metabolic pathway analysis revealed that the pathways related to the metabolism of carbohydrates, amino acids, cofactors, and vitamins accounted for more than 10% of the enriched pathways throughout the fermentation period. Concisely, we show that cellulase can effectively improve the nutritional value of PCGM when synergized with B. velezensis in two-stage SSF.

Effect of Acute and Chronic Ingestion of Exogenous Ketone Supplements on Blood Pressure: A Systematic Review and Meta-Analysis

Exogenous ketone supplements have been suggested to have potential cardiovascular benefits, but their overall effect on blood pressure is unclear. Our objective was to perform a systematic review and meta-analysis on the effects of exogenous ketone supplements on blood pressure (BP) and concomitant changes in resting heart rate (HR). Five databases were searched on January 27th, 2023, for randomized and non-randomized studies. A random-effects model meta-analysis was performed including all studies jointly and separately for acute and chronic ingestion of ketone supplements. Out of 4012 studies identified in the search, 4 acute and 6 chronic studies with n = 187 participants were included. Pooled results (n = 10) showed no change in systolic (SMD [95% CI]= -0.14 [-0.40; 0.11]; I2= 30%; p = 0.17) or diastolic BP (-0.12 [-0.30; 0.05]; I2= 0%; p = 0.69), with a potential tendency observed toward increased resting heart rate (0.17 [-0.14; 0.47]; I2= 40%; p = 0.10). Similar results for systolic and diastolic BP were observed when assessing separately the effect of acute and chronic ingestion of ketone supplements (p ≥ 0.33). Supplement dosage was found to modulate the increase in resting heart rate (0.019 ± 0.006; p = 0.013; R2=100%), suggesting that higher supplement doses lead to a higher resting heart rate. Based on currently available data, acute or prolonged ingestion of ketone supplements does not seem to modulate BP. However, a tendency for HR to increase after acute ingestion was observed, particularly with higher doses. Higher quality studies with appropriate standardized measurements are needed to confirm these results.

Colonic L-cell impairment in aged subjects with type 2 diabetes leads to diminished GLP-1 production

AIMS

Glucagon-like peptide 1 (GLP-1) is produced by the L subtype of enteroendocrine cells (EECs). Patients with type 2 diabetes (T2D) exhibit reduced incretin effect, but the pathophysiology and functional change of the L-cells remain unclear. Deciphering the mechanisms of the biological changes in L-cells under T2D conditions may assist in the research of gut-based strategies for T2D therapy.

METHODS

We investigated the fasting serum GLP-1 levels and the distribution of colonic L-cells in young and aged participants with and without T2D. Additionally, we established an aged male T2D Wistar rat model subjected to a long-term high-fat and high-fructose (HFHF) diet. Histological investigations and single-cell RNA sequencing (scRNA-seq) analyses were performed to explore the mechanisms underlying functional changes in the colonic EECs.

RESULTS

We observed a decline in circulating GLP-1 levels and a reduced number of colonic L-cells in elderly patients with T2D. The mechanisms underlying impaired L-cell formation and disturbed GLP-1 production were revealed using aged T2D rats induced by a long-term HFHF diet. The scRNA-seq results showed that the transcription factors that regulate L-cell commitment, such as Foxa1, were downregulated, and the expression of genes that participate in encoding GLP-1, GLP-1 posttranslational processing, hormone secretion, and nutrient sensing was disturbed.

CONCLUSIONS

Taken together, the reduced L-cell lineage commitment and disturbed L-cell functions might be the major cause of the reduced GLP-1 production in aged populations with T2D. Our study provides new insights for identifying novel targets in colonic L-cells for improving endogenous GLP-1 production.

DNA methylome and transcriptome profiling reveal key electrophysiology and immune dysregulation in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease. However, a detailed DNA methylation (DNAme) landscape has not yet been elucidated. Our study combined DNAme and transcriptome profiles for HCM myocardium and identify aberrant DNAme associated with altered myocardial function in HCM. The transcription of methylation-related genes did not significantly differ between HCM and normal myocardium. Nevertheless, the former had an altered DNAme profile compared with the latter. The hypermethylated and hypomethylated sites in HCM tissues had chromosomal distributions and functional enrichment of correlated genes differing from those of their normal tissue counterparts. The GO analysis of network underlying the genes correlated with DNAme alteration and differentially expressed genes (DEGs) shows functional clusters centred on immune cell function and muscle system processes. In KEGG analysis, only the calcium signalling pathway was enriched either by the genes correlated with changes in DNAme or DEGs. The protein-protein interactions (PPI) underlying the genes altered at both the DNAme and transcriptional highlighted two important functional clusters. One of these was related to the immune response and had the estrogen receptor-encoding ESR1 gene as its node. The other cluster comprised cardiac electrophysiology-related genes. Intelliectin-1 (ITLN1), a component of the innate immune system, was transcriptionally downregulated in HCM and had a hypermethylated site within 1500 bp upstream of the ITLN1 transcription start site. Estimates of immune infiltration demonstrated a relative decline in immune cell population diversity in HCM. A combination of DNAme and transcriptome profiles may help identify and develop new therapeutic targets for HCM.

Gut feelings in the islets: The role of the gut microbiome and the FFA2 and FFA3 receptors for short chain fatty acids on β-cell function and metabolic regulation

Short-chain fatty acids (SCFAs) are biosynthesized via fermentation of polysaccharides by gastrointestinal microbiota and have been shown to have wide-reaching effects on almost all tissues, including the pancreatic islets. Historically, the effects of SCFAs have been attributed to their intracellular metabolism and function as energy sources, but the discovery of free fatty acid G protein-coupled receptors (GPCRs) in the 2000s suggested that many functional outcomes of SCFAs are receptor-mediated. The SCFA receptors FFA2/GPR43 and FFA3/GPR41 are expressed on β-cells, where they regulate glucose-dependent insulin secretion, making them attractive targets for treatment of diabetes and other metabolic disorders. Here, we provide an update on the current evidence regarding regulation of FFA2/FFA3 receptors by specific probiotic bacterial species within the gut microbiome that synthesize SCFAs. We also review the body of research regarding the FFA2- and FFA3 receptor-specific function of SCFAs on β-cells and discuss the somewhat controversial and opposing findings within these studies.

Short-chain fatty acids are potential goalkeepers of atherosclerosis

Short-chain fatty acids (SCFAs) are metabolites produced by gut bacteria and play a crucial role in various inflammatory diseases. Increasing evidence suggests that SCFAs can improve the occurrence and progression of atherosclerosis. However, the molecular mechanisms through which SCFAs regulate the development of atherosclerosis have not been fully elucidated. This review provides an overview of the research progress on SCFAs regarding their impact on the risk factors and pathogenesis associated with atherosclerosis, with a specific focus on their interactions with the endothelium and immune cells. These interactions encompass the inflammation and oxidative stress of endothelial cells, the migration of monocytes/macrophages, the lipid metabolism of macrophages, the proliferation and migration of smooth muscle cells, and the proliferation and differentiation of Treg cells. Nevertheless, the current body of research is insufficient to comprehensively understand the full spectrum of SCFAs' mechanisms of action. Therefore, further in-depth investigations are imperative to establish a solid theoretical foundation for the development of clinical therapeutics in this context.

Anti-Malassezia Drug Candidates Based on Virulence Factors of Malassezia-Associated Diseases

Malassezia is a lipophilic unicellular fungus that is able, under specific conditions, to cause severe cutaneous and systemic diseases in predisposed subjects. This review is divided into two complementary parts. The first one discusses how virulence factors contribute to Malassezia pathogenesis that triggers skin diseases. These virulence factors include Malassezia cell wall resistance, lipases, phospholipases, acid sphingomyelinases, melanin, reactive oxygen species (ROS), indoles, hyphae formation, hydrophobicity, and biofilm formation. The second section describes active compounds directed specifically against identified virulence factors. Among the strategies for controlling Malassezia spread, this review discusses the development of aryl hydrocarbon receptor (AhR) antagonists, inhibition of secreted lipase, and fighting biofilms. Overall, this review offers an updated compilation of Malassezia species, including their virulence factors, potential therapeutic targets, and strategies for controlling their spread. It also provides an update on the most active compounds used to control Malassezia species.

Impact of gut microbiome on the renin-aldosterone system: Shika-machi Super Preventive Health Examination results

The renin-angiotensin-aldosterone system (RAAS) is a regulatory mechanism of the endocrine system and is associated with various diseases, including hypertension and renal and cardiovascular diseases. The gut microbiota (GM) have been associated with various diseases, mainly in animal models. However, to our knowledge, no studies have examined the relationship between the RAAS and GM in humans. The present study aimed to assess the association between the systemic RAAS and GM genera and their causal relationships. The study participants were 377 members of the general population aged 40 years or older in Shika-machi, Japan. Plasma renin activity (PRA), plasma aldosterone concentration (PAC), aldosterone-renin ratio (ARR), and GM composition were analyzed using the 16S rRNA method. The participants were divided into high and low groups according to the PRA, PAC, and ARR values. U-tests, one-way analysis of covariance, and linear discriminant analysis of effect size were used to identify the important bacterial genera between the two groups, and binary classification modeling using Random Forest was used to calculate the importance of the features. The results showed that Blautia, Bacteroides, Akkermansia, and Bifidobacterium were associated with the RAAS parameters. Causal inference analysis using the linear non-Gaussian acyclic model revealed a causal effect of Blautia on PAC via SBP. These results strengthen the association between the systemic RAAS and GM in humans, and interventions targeting the GM may provide new preventive measures and treatments for hypertension and renal disease.

Effect of hexavalent chromium on growth performance and metabolism in broiler chicken

Hexavalent chromium Cr (VI) is one of the most hazardous heavy metals in the environment and is toxic to living organisms causing tissue damage, disruption of the intestinal microbiota and cancer. However, there is little information on the relationship between the Cr (VI) and broiler chickens. The current study was performed to investigate the effect of Cr (VI) on growth performance, serum biochemical analysis, histopathological observations, and metabolomics analysis in broilers. Results show that Cr (VI) exposure significantly decreased the body weight (p < 0.01) and caused liver damages in broilers. With the extension of Cr (VI) action time, the liver appeared obvious pathological changes, including hepatic cord disorder, incomplete hepatocyte additionally, decreased serum biochemical indices of calcium (Ca), phosphorus (P), total protein (TP), phosphatase (ALP), and globin (GLB) significantly (p < 0.01). Moreover, metabolomics analysis indicated that 29 differential metabolites were identified, such as phytosphingosine, L-Serine, 12, 13-DHOME, Alpha-dimorphecolic acid, L-Methionine, L-Phenylalanine, 3-Dehydroshikimate, L-Tyrosine, and N-Acetyl-L-phenylalanine were significantly decreased under the action of Cr (VI) (p < 0.05). These 29 differential metabolites are mainly involved in 35 metabolic pathways, such as aminoacyl-tRNA biosynthesis, phenylalanine metabolism, sphingolipid, and linoleic metabolism. The study revealed that exposure to Cr (VI) resulted in a decrease in growth performance and metabolism, with the hazards and toxicity in broiler chicken. The findings provided new insight and a comprehensive understanding of the relationship between Cr (VI) and broiler chickens.

Human Gut Microbiota in Heart Failure: Trying to Unmask an Emerging Organ

There is a bidirectional relationship between the heart and the gut. The gut microbiota, the community of gut micro-organisms themselves, is an excellent gut-homeostasis keeper since it controls the growth of potentially harmful bacteria and protects the microbiota environment. There is evidence suggesting that a diet rich in fatty acids can be metabolized and converted by gut microbiota and hepatic enzymes to trimethyl-amine N-oxide (TMAO), a product that is associated with atherogenesis, platelet dysfunction, thrombotic events, coronary artery disease, stroke, heart failure (HF), and, ultimately, death. HF, by inducing gut ischemia, congestion, and, consequently, gut barrier dysfunction, promotes the intestinal leaking of micro-organisms and their products, facilitating their entrance into circulation and thus stimulating a low-grade inflammation associated with an immune response. Drugs used for HF may alter the gut microbiota, and, conversely, gut microbiota may modify the pharmacokinetic properties of the drugs. The modification of lifestyle based mainly on exercise and a Mediterranean diet, along with the use of pre- or probiotics, may be beneficial for the gut microbiota environment. The potential role of gut microbiota in HF development and progression is the subject of this review.

Association of Short-Chain Fatty Acids with Gut Microbiota and Lipid Metabolism in Mice with Diarrhea Induced by High-Fat Diet in a Fatigued State

SCOPE

Preliminary research finds that a high-fat diet (HFD) in a fatigued state triggers diarrhea, but the exact mechanism has not been clarified. To address concerns about the pathogenesis of diarrhea, the study evaluates the composition and metabolomics of the gut microbiota.

METHODS AND RESULTS

The study uses the multiple platform apparatus device to induce fatigue in mice, combined with intragastric administration of lard-caused diarrhea. Subsequently, the characteristics and interaction relationship of gut microbiota, short-chain fatty acids (SCFAs), inflammatory biomarkers, brain-gut peptides, and lipid metabolism are analyzed at the end of the experiment. HFD in a fatigued state results in a significant increase in interleukin-17, interleukin-6, cholecystokinin, somatostatin, and malondialdehyde content in mice (p < 0.05), along with a substantial decrease in high-density lipoprotein (p < 0.05). Additionally, an HFD in a fatigued state causes changes in the structure and composition of the gut microbiota, with Lactobacillus murinus as its characteristic bacteria, and reduces the production of SCFAs.

CONCLUSIONS

An HFD in a fatigued state triggers diarrhea, possibly associated with gut content microbiota dysbiosis, SCFAs deprivation, increased inflammation, and dysregulated lipid metabolism.

The impact of microbiota-derived short-chain fatty acids on macrophage activities in disease: Mechanisms and therapeutic potentials

Short-chain fatty acids (SCFAs) derived from the fermentation of carbohydrates by gut microbiota play a crucial role in regulating host physiology. Among them, acetate, propionate, and butyrate are key players in various biological processes. Recent research has revealed their significant functions in immune and inflammatory responses. For instance, butyrate reduces the development of interferon-gamma (IFN-γ) generating cells while promoting the development of regulatory T (Treg) cells. Propionate inhibits the initiation of a Th2 immune response by dendritic cells (DCs). Notably, SCFAs have an inhibitory impact on the polarization of M2 macrophages, emphasizing their immunomodulatory properties and potential for therapeutics. In animal models of asthma, both butyrate and propionate suppress the M2 polarization pathway, thus reducing allergic airway inflammation. Moreover, dysbiosis of gut microbiota leading to altered SCFA production has been implicated in prostate cancer progression. SCFAs trigger autophagy in cancer cells and promote M2 polarization in macrophages, accelerating tumor advancement. Manipulating microbiota- producing SCFAs holds promise for cancer treatment. Additionally, SCFAs enhance the expression of hypoxia-inducible factor 1 (HIF-1) by blocking histone deacetylase, resulting in increased production of antibacterial effectors and improved macrophage-mediated elimination of microorganisms. This highlights the antimicrobial potential of SCFAs and their role in host defense mechanisms. This comprehensive review provides an in-depth analysis of the latest research on the functional aspects and underlying mechanisms of SCFAs in relation to macrophage activities in a wide range of diseases, including infectious diseases and cancers. By elucidating the intricate interplay between SCFAs and macrophage functions, this review aims to contribute to the understanding of their therapeutic potential and pave the way for future interventions targeting SCFAs in disease management.

Induction of AHR Signaling in Response to the Indolimine Class of Microbial Stress Metabolites

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that plays an important role in gastrointestinal barrier function, tumorigenesis, and is an emerging drug target. The resident microbiota is capable of metabolizing tryptophan to metabolites that are AHR ligands (e.g., indole-3-acetate). Recently, a novel set of mutagenic tryptophan metabolites named indolimines have been identified that are produced by M. morganii in the gastrointestinal tract. Here, we determined that indolimine-200, -214, and -248 are direct AHR ligands that can induce Cyp1a1 transcription and subsequent CYP1A1 enzymatic activity capable of metabolizing the carcinogen benzo(a)pyrene in microsomal assays. In addition, indolimines enhance IL6 expression in a colonic tumor cell line in combination with cytokine treatment. The concentration of indolimine-248 that induces AHR transcriptional activity failed to increase DNA damage. These observations reveal an additional aspect of how indolimines may alter colonic tumorigenesis beyond mutagenic activity.

New Therapeutics for Heart Failure: Focusing on cGMP Signaling

Current drugs for treating heart failure (HF), for example, angiotensin II receptor blockers and β-blockers, possess specific target molecules involved in the regulation of the cardiac circulatory system. However, most clinically approved drugs are effective in the treatment of HF with reduced ejection fraction (HFrEF). Novel drug classes, including angiotensin receptor blocker/neprilysin inhibitor (ARNI), sodium-glucose co-transporter-2 (SGLT2) inhibitor, hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker, soluble guanylyl cyclase (sGC) stimulator/activator, and cardiac myosin activator, have recently been introduced for HF intervention based on their proposed novel mechanisms. SGLT2 inhibitors have been shown to be effective not only for HFrEF but also for HF with preserved ejection fraction (HFpEF). In the myocardium, excess cyclic adenosine monophosphate (cAMP) stimulation has detrimental effects on HFrEF, whereas cyclic guanosine monophosphate (cGMP) signaling inhibits cAMP-mediated responses. Thus, molecules participating in cGMP signaling are promising targets of novel drugs for HF. In this review, we summarize molecular pathways of cGMP signaling and clinical trials of emerging drug classes targeting cGMP signaling in the treatment of HF.

Compositional alterations of the gut microbiota in acute myocardial infarction patients with type 2 diabetes mellitus

Background

Type 2 diabetes mellitus (T2DM) is a risk factor for acute myocardial infarction (AMI) and a common comorbidity in patients with AMI. T2DM doubles the fatality rate of patients with AMI in the acute phase of AMI and the follow-up period. However, the mechanisms by which T2DM increases the fatality rate remain unknown. This study sought to investigate changes in the gut microbiota of patients with AMI and T2DM (AMIDM) to extend understandings of the relative mechanisms from the aspects of gut microbiota.

Methods

Patients were recruited and divided into 2 groups comprising 15 patients with AMIDM and 15 patients with AMI but without T2DM (AMINDM). Their stool samples and clinical information were collected. 16S ribosomal DNA sequencing was used to analyze the structure and composition of the gut microbiota based on the operational taxonomic units.

Results

A significant difference was observed in the gut microbiota β diversity between the 2 groups. At the phylum level, the AMIDM patients showed an increase in the abundance of Firmicutes and a decrease in the abundance of Bacteroidetes compared to the AMINDM patients. At the genus level, the AMIDM patients showed an increase in the abundance of Companilactobacillus, Defluvitaleaceae UCG-011 and UCG-009, and a decrease in the abundance of Phascolarctobacterium and CAG 56 compared to the AMINDM patients. At the species level, the AMIDM patients showed an increase in the abundance of species unclassified NK4A214 group, Bacteroides clarus, Coprococcus comes, unclassified Defluviltaleaceae UCG-011, uncultured rumen bacterium, unclassified CAG 56, Barnesiella intestinihominis, Lachnospiraceae bacterium, Bacteroides nordii, unclassified UCG-009, and the Family XIII AD3011 group compared to the AMINDM patients. The gut microbiota function predictions indicated that the nucleotide metabolism-related pathway was significantly more increase in the patients with AMIDM than those with AMINDM. Additionally, the patients with AMIDM showed an increase in gram-positive bacteria and a decrease in the proportion of gram-negative bacteria. Our correlation analysis results on the gut microbiota and clinical parameters might extend understandings of the progression of AMI.

Conclusions

Changes in the gut microbiota composition of patients with AMIDM affect the severity of the metabolic disturbance and may be responsible for poorer clinical outcomes and worse disease progression in patients with AMIDM compared to those with AMINDM.

Gut microbiota short-chain fatty acids and their impact on the host thyroid function and diseases

Thyroid disorders are clinically characterized by alterations of L-3,5,3',5'-tetraiodothyronine (T4), L-3,5,3'-triiodothyronine (T3), and/or thyroid-stimulating hormone (TSH) levels in the blood. The most frequent thyroid disorders are hypothyroidism, hyperthyroidism, and hypothyroxinemia. These conditions affect cell differentiation, function, and metabolism. It has been reported that 40% of the world's population suffers from some type of thyroid disorder and that several factors increase susceptibility to these diseases. Among them are iodine intake, environmental contamination, smoking, certain drugs, and genetic factors. Recently, the intestinal microbiota, composed of more than trillions of microbes, has emerged as a critical player in human health, and dysbiosis has been linked to thyroid diseases. The intestinal microbiota can affect host physiology by producing metabolites derived from dietary fiber, such as short-chain fatty acids (SCFAs). SCFAs have local actions in the intestine and can affect the central nervous system and immune system. Modulation of SCFAs-producing bacteria has also been connected to metabolic diseases, such as obesity and diabetes. In this review, we discuss how alterations in the production of SCFAs due to dysbiosis in patients could be related to thyroid disorders. The studies reviewed here may be of significant interest to endocrinology researchers and medical practitioners.

Oral Microalgae-Nano Integrated System against Radiation-Induced Injury

The increasing applications of ionizing radiation in society raise the risk of radiation-induced intestinal and whole-body injury. Astaxanthin is a powerful antioxidant to reduce the reactive oxygen generated from radiation and the subsequent damage. However, the oral administration of astaxanthin remains challenging owing to its low solubility and poor bioavailability. Herein, we facilely construct an orally used microalgae-nano integrated system (SP@ASXnano) against radiation-induced intestinal and whole-body injury, combining natural microalgae Spirulina platensis (SP) with astaxanthin nanoparticles (ASXnano). SP and ASXnano show complementation in drug delivery to improve distribution in the intestine and blood. SP displays limited gastric drug loss, prolonged intestinal retention, constant ASXnano release, and progressive degradation. ASXnano improves drug solubility, gastric stability, cell uptake, and intestinal absorption. SP and ASXnano have synergy in many aspects such as anti-inflammation, microbiota protection, and fecal short-chain fatty acid up-regulation. In addition, the system is ensured with biosafety for long-term administration. The system organically combines the properties of microalgae and nanoparticles, which was expected to expand the medical application of SP as a versatile drug delivery platform.

Significance of Endothelial Dysfunction Amelioration for Sodium-Glucose Cotransporter 2 Inhibitor-Induced Improvements in Heart Failure and Chronic Kidney Disease in Diabetic Patients

Beyond lowering plasma glucose levels, sodium-glucose cotransporter 2 inhibitors (SGLT2is) significantly reduce hospitalization for heart failure (HF) and retard the progression of chronic kidney disease (CKD) in patients with type 2 diabetes. Endothelial dysfunction is not only involved in the development and progression of cardiovascular disease (CVD), but is also associated with the progression of CKD. In patients with type 2 diabetes, hyperglycemia, insulin resistance, hyperinsulinemia and dyslipidemia induce the development of endothelial dysfunction. SGLT2is have been shown to improve endothelial dysfunction, as assessed by flow-mediated vasodilation, in individuals at high risk of CVD. Along with an improvement in endothelial dysfunction, SGLT2is have been shown to improve oxidative stress, inflammation, mitochondrial dysfunction, glucotoxicity, such as the advanced signaling of glycation end products, and nitric oxide bioavailability. The improvements in endothelial dysfunction and such endothelium-derived factors may play an important role in preventing the development of coronary artery disease, coronary microvascular dysfunction and diabetic cardiomyopathy, which cause HF, and play a role in retarding CKD. The suppression of the development of HF and the progression of CKD achieved by SGLT2is might have been largely induced by their capacity to improve vascular endothelial function.

Association between Intestinal Microecological Changes and Atherothrombosis

Atherosclerosis (AS) is a chronic inflammatory disease of large- and medium-sized arteries that causes ischemic heart disease, strokes, and peripheral vascular disease, collectively called cardiovascular disease (CVD), and is the leading cause of CVD resulting in a high rate of mortality in the population. AS is pathological by plaque development, which is caused by lipid infiltration in the vessel wall, endothelial dysfunction, and chronic low-grade inflammation. Recently, more and more scholars have paid attention to the importance of intestinal microecological disorders in the occurrence and development of AS. Intestinal G-bacterial cell wall lipopolysaccharide (LPS) and bacterial metabolites, such as oxidized trimethylamine (TMAO) and short-chain fatty acids (SCFAs), are involved in the development of AS by affecting the inflammatory response, lipid metabolism, and blood pressure regulation of the body. Additionally, intestinal microecology promotes the progression of AS by interfering with the normal bile acid metabolism of the body. In this review, we summarize the research on the correlation between maintaining a dynamic balance of intestinal microecology and AS, which may be potentially helpful for the treatment of AS.

Dietary 5-demethylnobiletin prevents antibiotic-associated dysbiosis of gut microbiota and damage to the colonic barrier

5-Demethylnobiletin (5DN) is an important ingredient of citrus extract that is rich in polymethoxyflavones (PMFs). In this study, we systemically investigated the preventive effects of 5DN on antibiotic-associated intestinal disturbances. Experimental mice were gavaged 0.2 mL per day of the antibiotic cocktail (12.5 g L^-1 cefuroxime and 10 g L^-1 levofloxacin) for 10 days, accompanied by dietary 0.05% 5DN for 10 and 20 days. The results showed that the combination of cefuroxime and levofloxacin caused swelling of the cecum and injury to the colon tissue. Meanwhile, the balance of intestinal oxidative stress and the barrier function of mice was also damaged by the antibiotics through upregulation of the relative mRNA levels of superoxide dismutase 3 (SOD3), quinine oxidoreductase 1 (NQO1) and glutathione peroxidase 1 (GPX1), and downregulation of the relative protein levels of tight junction proteins (TJs). Moreover, antibiotic exposure led to disorder of the gut microbiota, particularly increased harmful bacteria (Proteobacteria) and decreased beneficial bacteria (Bacteroideta). However, dietary 5DN could reduce antibiotic-associated intestinal damage, evidenced by the results that 5DN alleviated gut oxidative damage and attenuated intestinal barrier injury via increasing the expression of TJs including occludin and zonula occluden1 (ZO1). Additionally, dietary 5DN modulated the composition of the gut microbiota in antibiotic-treated mice by increasing the relative levels of beneficial bacteria, such as Dubosiella and Lactobacillus. Moreover, PMFs increased the contents of isobutyric acid and butyric acid, which were almost eliminated by antibiotic exposure. In conclusion, 5DN could alleviate antibiotic-related imbalance of intestinal oxidative stress, barrier function damage, intestinal flora disorders and the reduction of short-chain fatty acids (SCFAs), which lays a foundation for exploring safer and more effective ways to prevent or mitigate antibiotic-associated intestinal damage.

Metabolic Acidosis Results in Sexually Dimorphic Response in the Heart Tissue

Metabolic acidosis (MA) is a highly prevalent disorder in a significant proportion of the population, resulting from imbalance in blood pH homeostasis. The heart, being an organ with very low regenerative capacity and high metabolic activity, is vulnerable to chronic, although low-grade, MA. To systematically characterize the effect of low-grade MA on the heart, we treated male and female mice with NH4Cl supplementation for 2 weeks and analyzed their blood chemistry and transcriptomic signature of the heart tissue. The reduction of pH and plasma bicarbonate levels without an associated change in anion gap indicated a physiological manifestation of low-grade MA with minimal respiratory compensation. On transcriptomic analysis, we observed changes in cardiac-specific genes with significant gender-based differences due to MA. We found many genes contributing to dilated cardiomyopathy to be altered in males, more than in females, while cardiac contractility and Na/K/ATPase-Src signaling were affected in the opposite way. Our model presents a systems-level understanding of how the cardiovascular tissue is affected by MA. As low-grade MA is a common ailment with many dietary and pharmaceutical interventions, our work presents avenues to limit chronic cardiac damage and disease manifestation, as well as highlighting the sex differences in MA-induced cardiovascular damage.

Variation in responses to incretin therapy: Modifiable and non-modifiable factors

Type 2 diabetes (T2D) and obesity have reached epidemic proportions. Incretin therapy is the second line of treatment for T2D, improving both blood glucose regulation and weight loss. Glucagon-like peptide-1 (GLP-1) and glucose-stimulated insulinotropic polypeptide (GIP) are the incretin hormones that provide the foundations for these drugs. While these therapies have been highly effective for some, the results are variable. Incretin therapies target the class B G protein-coupled receptors GLP-1R and GIPR, expressed mainly in the pancreas and the hypothalamus, while some therapeutical approaches include additional targeting of the related glucagon receptor (GCGR) in the liver. The proper functioning of these receptors is crucial for incretin therapy success and here we review several mechanisms at the cellular and molecular level that influence an individual's response to incretin therapy.

Cardiac RGS Proteins in Human Heart Failure and Atrial Fibrillation: Focus on RGS4

The regulator of G protein signaling (RGS) proteins are crucial for the termination of G protein signals elicited by G protein-coupled receptors (GPCRs). This superfamily of cell membrane receptors, by far the largest and most versatile in mammals, including humans, play pivotal roles in the regulation of cardiac function and homeostasis. Perturbations in both the activation and termination of their G protein-mediated signaling underlie numerous heart pathologies, including heart failure (HF) and atrial fibrillation (AFib). Therefore, RGS proteins play important roles in the pathophysiology of these two devasting cardiac diseases, and several of them could be targeted therapeutically. Although close to 40 human RGS proteins have been identified, each RGS protein seems to interact only with a specific set of G protein subunits and GPCR types/subtypes in any given tissue or cell type. Numerous in vitro and in vivo studies in animal models, and also in diseased human heart tissue obtained from transplantations or tissue banks, have provided substantial evidence of the roles various cardiomyocyte RGS proteins play in cardiac normal homeostasis as well as pathophysiology. One RGS protein in particular, RGS4, has been reported in what are now decades-old studies to be selectively upregulated in human HF. It has also been implicated in protection against AFib via knockout mice studies. This review summarizes the current understanding of the functional roles of cardiac RGS proteins and their implications for the treatment of HF and AFib, with a specific focus on RGS4 for the aforementioned reasons but also because it can be targeted successfully with small organic molecule inhibitors.

Association between short-chain fatty acid intake and development of muscle strength loss among community-dwelling older Japanese adults

BACKGROUND

Short-chain fatty acids (SCFAs) have been suggested to be associated with skeletal muscle mass maintenance. However, the role of dietary SCFAs in preserving muscle strength in the older population remains unclear.

OBJECTIVES

To clarify the longitudinal association between the dietary intake of SCFAs and the development of low muscle strength in older community dwellers.

METHODS

Data were obtained from the National Institute for Longevity Sciences-Longitudinal Study of Aging cohort. The participants included 441 men and 382 women who participated in the baseline survey (the fifth wave, between 2006 and 2008) and at least one follow-up examination (sixth to ninth waves, between 2008 and 2022) and were ≥60 years old and did not have low muscle strength (defined as a grip strength of <28 kg for men and <18 kg for women) at baseline. Baseline nutrient intakes were assessed with a 3-day dietary record. A generalized estimating equation was employed to estimate the odds ratio (OR) and 95 % confidence intervals (CIs) for low muscle strength per 1 standard deviation (SD) increase in the intake of SCFAs and other nutrients at baseline (adjusted for sex, age, follow-up time, baseline grip strength, physical activity, smoking, family income, education, and disease histories).

RESULTS

The mean (SD) follow-up time and number were 7.8 (3.2) years and 3.2 (1.0) times, respectively. Approximately 8.1 % of the participants exhibited muscle strength loss in at least one follow-up assessment. The multivariate-adjusted OR (95 % CIs) was 0.77 (0.63-0.93) for each 1-SD increase in SCFA intake (268 mg/day), and the ORs for the highest through the lowest tertiles of SCFA intake were 1.00 (reference), 1.44 (0.95-2.17), and 1.83 (1.20-2.78), respectively (trend p = 0.005). The results remained significant after multivariate adjusting for energy or fat intake.

CONCLUSION

Dietary intake of SCFAs may prevent muscle strength decline in community-dwelling older adults.

Moderating Gut Microbiome/Mitochondrial Axis in Oxazolone Induced Ulcerative Colitis: The Evolving Role of β-Glucan and/or, Aldose Reductase Inhibitor, Fidarestat

A mechanistic understanding of the dynamic interactions between the mitochondria and the gut microbiome is thought to offer innovative explanations for many diseases and thus provide innovative management approaches, especially in GIT-related autoimmune diseases, such as ulcerative colitis (UC). β-Glucans, important components of many nutritious diets, including oats and mushrooms, have been shown to exhibit a variety of biological anti-inflammatory and immune-modulating actions. Our research study sought to provide insight into the function of β-glucan and/or fidarestat in modifying the microbiome/mitochondrial gut axis in the treatment of UC. A total of 50 Wistar albino male rats were grouped into five groups: control, UC, β-Glucan, Fidarestat, and combined treatment groups. All the groups were tested for the presence of free fatty acid receptors 2 and 3 (FFAR-2 and -3) and mitochondrial transcription factor A (TFAM) mRNA gene expressions. The reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and ATP content were found. The trimethylamine N-oxide (TMAO) and short-chain fatty acid (SCFA) levels were also examined. Nuclear factor kappa β (NF-kβ), nuclear factor (erythroid-2)-related factor 2 (Nrf2) DNA binding activity, and peroxisome proliferator-activated receptor gamma co-activator-1 (PGC-1) were identified using the ELISA method. We observed a substantial increase FFAR-2, -3, and TFAM mRNA expression after the therapy. Similar increases were seen in the ATP levels, MMP, SCFA, PGC-1, and Nrf2 DNA binding activity. The levels of ROS, TMAO, and NF-kβ, on the other hand, significantly decreased. Using β-glucan and fidarestat together had unique therapeutic benefits in treating UC by focusing on the microbiota/mitochondrial axis, opening up a new avenue for a potential treatment for such a complex, multidimensional illness.

Circulating expression patterns of TL1A and FFAR2 in patients with stable and unstable angina

Background and aim

The primary factor in sudden cardiac death is coronary artery disease. We intended to discover the diagnostic worth of circulating tumor necrosis factor like cytokine 1A (TL1A) and free fatty acid receptor 2 (FFAR2) as early, noninvasive indicators for individuals with stable angina (SA) and unstable angina (UA).

Methods

In all, 90 people were enrolled in the current case–control study: 30 patients with SA, 30 patients with UA, and 30 healthy volunteers. Circulating TL1A and FFAR2 gene expression levels were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). FBG, TC, TG, and HDL-C were assessed by spectrophotometry, while hs-CRP and troponin T were measured by ELISA.

Results

Circulating TL1A expression was significantly elevated in SA (P < 0.001) and UA patients (P < 0.001) as compared to controls and also was significantly higher in UA patients (P < 0.001) as compared to SA patients. Circulating FFAR2 expression was significantly decreased in SA (P < 0.001) and UA patients (P < 0.001) in comparison with controls and was significantly lowered in UA patients (P = 0.001) in comparison with SA patients. Our results show that TL1A and FFAR2 were sensitive and specific biomarkers for discriminating SA patients from controls. Moreover, TL1A and FFAR2 displayed a remarkable ability to distinguish UA from SA. Multivariate regression analysis revealed that TL1A, FFAR2, FBG, TC, TG, LDL-C, and Troponin T were independent risk factors for SA, while TL1A, TG, and hs-CRP were independent risk factors for UA. TL1A has a significant positive correlation with LDL-C (r = 0.406, P = 0.001), hs-CRP (r = 0.673, P < 0.001), and troponin T (r = 0.653, P < 0.001). There was a significant inverse relationship between FFAR2 and each of TL1A (r = − 0.858, P < 0.001), FBG (r = − 0.325, P = 0.011), TC(r = − 0.306, P = 0.017), TG (r = − 0.368, P = 0.004), LDL-C (r = − 0.413, P = 0.001), hs-CRP (r = − 0.737, P < 0.001), and troponin T (r = − 0.715, P < 0.001).

Conclusion

Gene expression of TL1A and FFAR2 is a good new blood-based molecular indicator for early detection of SA and UA. Early detection of a possible UA is crucial for initiating appropriate treatment that results in better patient health.

The therapeutic potential of targeting cardiac RGS4

G protein-coupled receptors (GPCRs) play pivotal roles in regulation of cardiac function and homeostasis. To function properly, every cell needs these receptors to be stimulated only when a specific extracellular stimulus is present, and to be silenced the moment that stimulus is removed. The regulator of G protein signaling (RGS) proteins are crucial for the latter to occur at the cell membrane, where the GPCR normally resides. Perturbations in both activation and termination of G protein signaling underlie numerous heart pathologies. Although more than 30 mammalian RGS proteins have been identified, each RGS protein seems to interact only with a specific set of G protein subunits and GPCR types/subtypes in any given tissue or cell type, and this applies to the myocardium as well. A large number of studies have provided substantial evidence for the roles various RGS proteins expressed in cardiomyocytes play in cardiac physiology and heart disease pathophysiology. This review summarizes the current understanding of the functional roles of cardiac RGS proteins and their implications for the treatment of specific heart diseases, such as heart failure and atrial fibrillation. We focus on cardiac RGS4 in particular, since this isoform appears to be selectively (among the RGS protein family) upregulated in human heart failure and is also the target of ongoing drug discovery efforts for the treatment of a variety of diseases.

Changes in the gut microbiome of patients with type a aortic dissection

Objective

To investigate the characteristic changes in the gut microbiota of patients with type A aortic dissection (AAD) and provide a theoretical basis for future microbiome-oriented interventional studies.

Methods

High-throughput 16S rDNA sequencing was performed on the stool samples of patients with and without (healthy control subjects) AAD. Using alpha and beta diversity analysis, we compared the gut microbiota composition of 20 patients with AAD and 20 healthy controls matched for gender, age, BMI, and geographical region. The accuracy of AAD prediction by differential microbiome was calculated using the random forest machine learning model. Targeted measurement of the plasma concentration of short-chain fatty acids (SCFAs), which are the main metabolites of the gut microbiome, was performed using gas chromatography-mass spectrometry (GC-MS). Spearman's correlation analysis was conducted to determine the relationships of gut microbiome and SCFAs with the clinical characteristics of subjects.

Results

The differences in gut microbiota alpha diversity between patients with AAD and the healthy controls were not statistically significant (Shannon index: p = 0.19; Chao1: p = 0.4); however, the microbiota composition (beta diversity) was significantly different between the two groups (Anosim, p = 0.001). Bacteroidota was enriched at the phylum level, and the SCFA-producing genera Prevotella, Porphyromonas, Lachnospiraceae, and Ruminococcus and inflammation-related genera Fenollaria and Sutterella were enriched at the genus level in the AAD group compared with those in the control group. The random forest model could predict AAD from gut microbiota composition with an accuracy of 87.5% and the area-under-curve (AUC) of the receiver operating characteristic curve was 0.833. The SCFA content of patients with AAD was higher than that of the control group, with the difference being statistically significant (p < 0.05). The different microflora and SCFAs were positively correlated with inflammatory cytokines.

Conclusion

To the best of our knowledge, this is the first demonstration of the presence of significant differences in the gut microbiome of patients with AAD and healthy controls. The differential microbiome exhibited high predictive potential toward AAD and was positively correlated with inflammatory cytokines. Our results will assist in the development of preventive and therapeutic treatment methods for patients with AAD.

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.

Modulation of adipose tissue metabolism by microbial-derived metabolites

Obesity and its complications, including type 2 diabetes, cardiovascular disease, and certain cancers, have posed a significant burden on health and healthcare systems over the years due to their high prevalence and incidence. Gut microbial derivatives are necessary for the regulation of energy metabolism and host immunity, as well as for maintaining homeostasis of the intestinal environment. Gut flora metabolites may be a link between gut microbes and diseases, such as obesity, and help understand why alterations in the microbiota can influence the pathophysiology of human disease. This is supported by emerging evidence that microbial-derived metabolites, such as short-chain fatty acids, bile acids, tryptophan, trimethylamine-N-oxide, and lipopolysaccharides, can be beneficial or detrimental to the host by affecting organs outside the gut, including adipose tissue. Adipose tissue is the largest lipid storage organ in the body and an essential endocrine organ that plays an indispensable role in the regulation of lipid storage, metabolism, and energy balance. Adipose tissue metabolism includes adipocyte metabolism (lipogenesis and lipolysis), thermogenesis, and adipose tissue metabolic maladaptation. Adipose tissue dysfunction causes the development of metabolic diseases, such as obesity. Here, we review the current understanding of how these microbial metabolites are produced and discuss both established mechanisms and the most recent effects of microbial products on host adipose tissue metabolism. We aimed to identify novel therapeutic targets or strategies for the prevention and treatment of obesity and its complications.

Autonomic Nervous System Regulation of Epicardial Adipose Tissue: Potential Roles for Regulator of G Protein Signaling-4

The epicardial adipose tissue (EAT) or epicardial fat is a visceral fat depot in the heart that contains intrinsic adrenergic and cholinergic nerves, through which it interacts with the cardiac sympathetic (adrenergic) and parasympathetic (cholinergic) nervous systems. These EAT nerves represent a significant source of several adipokines and other bioactive molecules, including norepinephrine, epinephrine, and free fatty acids. The production of these molecules is biologically relevant for the heart, since abnormalities in EAT secretion are implicated in the development of pathological conditions, including coronary atherosclerosis, atrial fibrillation, and heart failure. Sympathetic hyperactivity and parasympathetic (cholinergic) derangement are associated with EAT dysfunction, leading to a variety of adverse cardiac conditions, such as heart failure, diastolic dysfunction, atrial fibrillation, etc.; therefore, several studies have focused on exploring the autonomic regulation of EAT as it pertains to heart disease pathogenesis and progression. In addition, Regulator of G protein Signaling (RGS)-4 is a protein with significant regulatory roles in both adrenergic and muscarinic receptor signaling in the heart. In this review, we provide an overview of the autonomic regulation of EAT, with a specific focus on cardiac RGS4 and the potential roles this protein plays in this regulation.

Investigational Microbiological Therapy for Glioma

Glioma is the most common primary malignancy of the central nervous system (CNS), and 50% of patients present with glioblastoma (GBM), which is the most aggressive type. Currently, the most popular therapies are progressive chemotherapy and treatment with temozolomide (TMZ), but the median survival of glioma patients is still low as a result of the emergence of drug resistance, so we urgently need to find new therapies. A growing number of studies have shown that the diversity, bioactivity, and manipulability of microorganisms make microbial therapy a promising approach for cancer treatment. However, the many studies on the research progress of microorganisms and their derivatives in the development and treatment of glioma are scattered, and nobody has yet provided a comprehensive summary of them. Therefore, in this paper, we review the research progress of microorganisms and their derivatives in the development and treatment of glioma and conclude that it is possible to treat glioma by exogenous microbial therapies and targeting the gut-brain axis. In this article, we discuss the prospects and pressing issues relating to these therapies with the aim of providing new ideas for the treatment of glioma.

Short-Chain Fatty Acids in Gut-Heart Axis: Their Role in the Pathology of Heart Failure

Heart failure (HF) is a syndrome with global clinical and socioeconomic burden worldwide owing to its poor prognosis. Accumulating evidence has implicated the possible contribution of gut microbiota-derived metabolites, short-chain fatty acids (SCFAs), on the pathology of a variety of diseases. The changes of SCFA concentration were reported to be observed in various cardiovascular diseases including HF in experimental animals and humans. HF causes hypoperfusion and/or congestion in the gut, which may lead to lowered production of SCFAs, possibly through the pathological changes of the gut microenvironment including microbiota composition. Recent studies suggest that SCFAs may play a significant role in the pathology of HF, possibly through an agonistic effect on G-protein-coupled receptors, histone deacetylases (HDACs) inhibition, restoration of mitochondrial function, amelioration of cardiac inflammatory response, its utilization as an energy source, and remote effect attributable to a protective effect on the other organs. Collectively, in the pathology of HF, SCFAs might play a significant role as a key mediator in the gut-heart axis. However, these possible mechanisms have not been entirely clarified and need further investigation.

Learn from failures and stay hopeful to GPR40, a GPCR target with robust efficacy, for therapy of metabolic disorders

GPR40 is a class A G-protein coupled receptor (GPCR) mainly expressed in pancreas, intestine, and brain. Its endogenous ligand is long-chain fatty acids, which activate GPR40 after meal ingestion to induce secretion of incretins in the gut, including GLP-1, GIP, and PYY, the latter control appetite and glucose metabolism. For its involvement in satiety regulation and metabolic homeostasis, partial and AgoPAM (Positive Allosteric Modulation agonist) GPR40 agonists had been developed for type 2 diabetes (T2D) by many pharmaceutical companies. The proof-of-concept of GPR40 for control of hyperglycemia was achieved by clinical trials of partial GPR40 agonist, TAK-875, demonstrating a robust decrease in HbA1c (-1.12%) after chronic treatment in T2D. The development of TAK-875, however, was terminated due to liver toxicity in 2.7% patients with more than 3-fold increase of ALT in phase II and III clinical trials. Different mechanisms had since been proposed to explain the drug-induced liver injury, including acyl glucuronidation, inhibition of mitochondrial respiration and hepatobiliary transporters, ROS generation, etc. In addition, activation of GPR40 by AgoPAM agonists in pancreas was also linked to β-cell damage in rats. Notwithstanding the multiple safety concerns on the development of small-molecule GPR40 agonists for T2D, some partial and AgoPAM GPR40 agonists are still under clinical development. Here we review the most recent progress of GPR40 agonists development and the possible mechanisms of the side effects in different organs, and discuss the possibility of developing novel strategies that retain the robust efficacy of GPR40 agonists for metabolic disorders while avoid toxicities caused by off-target and on-target mechanisms.

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.

The role of the gut microbiota in health and cardiovascular diseases

The gut microbiota is critical to human health, such as digesting nutrients, forming the intestinal epithelial barrier, regulating immune function, producing vitamins and hormones, and producing metabolites to interact with the host. Meanwhile, increasing evidence indicates that the gut microbiota has a strong correlation with the occurrence, progression and treatment of cardiovascular diseases (CVDs). In patients with CVDs and corresponding risk factors, the composition and ratio of gut microbiota have significant differences compared with their healthy counterparts. Therefore, gut microbiota dysbiosis, gut microbiota-generated metabolites, and the related signaling pathway may serve as explanations for some of the mechanisms about the occurrence and development of CVDs. Several studies have also demonstrated that many traditional and latest therapeutic treatments of CVDs are associated with the gut microbiota and its generated metabolites and related signaling pathways. Given that information, we summarized the latest advances in the current research regarding the effect of gut microbiota on health, the main cardiovascular risk factors, and CVDs, highlighted the roles and mechanisms of several metabolites, and introduced corresponding promising treatments for CVDs regarding the gut microbiota. Therefore, this review mainly focuses on exploring the role of gut microbiota related metabolites and their therapeutic potential in CVDs, which may eventually provide better solutions in the development of therapeutic treatment as well as the prevention of CVDs.

Short-chain fatty acid: An updated review on signaling, metabolism, and therapeutic effects

Fatty acids are good energy sources (9 kcal per gram) that aerobic tissues can use except for the brain (glucose is an alternative source). Apart from the energy source, fatty acids are necessary for cell signaling, learning-related memory, modulating gene expression, and functioning as cytokine precursors. Short-chain fatty acids (SCFAs) are saturated fatty acids arranged as a straight chain consisting minimum of 6 carbon atoms. SCFAs possess various beneficial effects like improving metabolic function, inhibiting insulin resistance, and ameliorating immune dysfunction. In this review, we discussed the biogenesis, absorption, and transport of SCFA. SCFAs can act as signaling molecules by stimulating G protein-coupled receptors (GPCRs) and suppressing histone deacetylases (HDACs). The role of SCFA on glucose metabolism, fatty acid metabolism, and its effect on the immune system is also reviewed with updated details. SCFA possess anticancer, anti-diabetic, and hepatoprotective effects. Additionally, the association of protective effects of SCFA against brain-related diseases, kidney diseases, cardiovascular damage, and inflammatory bowel diseases were also reviewed. Nanotherapy is a branch of nanotechnology that employs nanoparticles at the nanoscale level to treat various ailments with enhanced drug stability, solubility, and minimal side effects. The SCFA functions as drug carriers, and nanoparticles were also discussed. Still, much research was not focused on this area. SCFA functions in host gene expression through inhibition of HDAC inhibition. However, the study has to be focused on the molecular mechanism of SCFA against various diseases that still need to be investigated.