From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites

The interactions between the host immunity and intestinal microorganisms in fish

There is a huge quantity of microorganisms in the gut of fish, which exert pivotal roles in maintaining host intestinal and general health. The fish immunity can sense and shape the intestinal microbiota and maintain the intestinal homeostasis. In the meantime, the intestinal commensal microbes regulate the fish immunity, control the extravagant proliferation of pathogenic microorganisms, and ensure the intestinal health of the host. This review summarizes developments and progress on the known interactions between host immunity and intestinal microorganisms in fish, focusing on the recent advances in zebrafish (Danio rerio) showing the host immunity senses and shapes intestinal microbiota, and intestinal microorganisms tune host immunity. This review will offer theoretical references for the development, application, and commercialization of intestinal functional microorganisms in fish. KEY POINTS: • The interactions between the intestinal microorganisms and host immunity in zebrafish • Fish immunity senses and shapes the microbiota • Intestinal microbes tune host immunity in fish.

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.

Modulation of gut microbiota and metabolites by Flammulina velutipes polysaccharides during in vitro human fecal fermentation: Unveiling Bacteroides as a potential primary degrader

Flammulina velutipes, a widely cultivated species of edible fungus, exhibits diverse functional activities attributed to its polysaccharides. In this study, we employed an in vitro model to investigate the impact of F. velutipes polysaccharides (FVP) fermentation on gut microbiota, with a particular focus on Bacteroides. FVP fermentation resulted in the proliferation of microbiota associated with short-chain fatty acid (SCFA) metabolism and suppression of Escherichia-Shigella. Bacteroides emerged as potential primary degraders of FVP, with species-level analysis identifying the preference of B. thetaiotaomicron and B. intestinalis in FVP degradation. Metabolomics analysis revealed significant increases in hypoxanthine and 7-methyladenine contents, with histidine metabolism emerging as the most enriched pathway. B. nordii and B. xylanisolvens exhibited the most influence on amino acid and SCFA metabolism. Understanding the mechanisms by which gut microbiota metabolize FVP can provide valuable insights into the potential of FVP to promote intestinal health and disease prevention.

Structural changes of rice starch-anthocyanins complexes (V-type) and its impact on gut microbiotas and potential metabolic pathways during in vitro fermentation

This study explored the differences in the in vitro fermentation properties of rice starch (RS) and rice starch-anthocyanins complexes (RS-A). Structural characterization suggested that RS and RS-A complexes showed a V-type crystalline structure. The degree of order (DO) and degree of double helix (DD) values of RS and RS-A complexes were enhanced after fermentation. Moreover, the RS-A complexes could improve the relative abundance of Bacteroidetes, Ruminococcaceae, and up-regulate gut microbiota diversity to maintain gut homeostasis. Relative abundance of potential metabolic pathways, such as energy metabolism, digestion system, and carbohydrate degradation overexpressed in the presence of RS-A complexes. The results demonstrated that the RS-A complexes had slower fermentation rates contributing to the transport of the formed short-chain fatty acid (SCFA) to the end of the colon and that the crystallinity might be a factor influencing the utilization of the starch matrix by the gut microbiota for SCFA formation.

Combined dilute alkali and milling process enhances the functionality and gut microbiota fermentability of insoluble corn fiber

In this study, we developed a process combining dilute alkali (NaOH or NaHCO3) and physical (disk milling and/or ball milling) treatments to improve the functionality and fermentability of corn fiber. The results showed that combining chemical with physical processes greatly improved the functionality and fermentability of corn fiber. Corn fiber treated with NaOH followed by disk milling (NaOH-DM-CF) had the highest water retention (19.5 g/g), water swelling (38.8 mL/g), and oil holding (15.5 g/g) capacities. Moreover, NaOH-DM-CF produced the largest amount (42.9 mM) of short-chain fatty acid (SCFA) during the 24-hr in vitro fermentation using porcine fecal inoculum. In addition, in vitro fermentation of NaOH-DM-CF led to a targeted microbial shifting to Prevotella (genus level), aligning with a higher fraction of propionic acid. The outstanding functionality and fermentability of NaOH-DM-CF were attributed to its thin and loose structure, decreased ester linkages and acetyl groups, and enriched structural carbohydrate exposure.

Structure-activity relationship studies of tetrahydroquinolone derivatives as GPR41 modulators

GPR41, a G protein-coupled receptor, serves as a sensor for short-chain fatty acids and plays a crucial role in regulating multiple physiological processes such as the maintenance of metabolic and immune homeostasis. Therefore, the modulation of GPR41 has garnered attention as a potential strategy for the treatment of various disorders. We conducted a structure-activity relationship study on a lead tetrahydroquinolone derivative bearing a 2-(trifluoromethoxy)benzene group that displayed antagonistic activity toward GPR41. Modification of the aryl group attached to the furan moiety revealed that derivatives containing di- or trifluorobenzene, instead of 2-(trifluoromethoxy)benzene, exhibited agonistic activity toward GPR41, comparable with the reported agonistic modulator AR420626. These results suggest that the aryl group plays a pivotal role in regulating the activity of compounds toward GPR41, providing valuable insights for the design of GPR41 modulators.

The immune and microbial homeostasis determines the Candida-mast cells cross-talk in celiac disease

Celiac disease (CD) is an autoimmune enteropathy resulting from an interaction between diet, genome, and immunity. Although many patients respond to a gluten-free diet, in a substantive number of individuals, the intestinal injury persists. Thus, other factors might amplify the ongoing inflammation. Candida albicans is a commensal fungus that is well adapted to the intestinal life. However, specific conditions increase Candida pathogenicity. The hypothesis that Candida may be a trigger in CD has been proposed after the observation of similarity between a fungal wall component and two CD-related gliadin T-cell epitopes. However, despite being implicated in intestinal disorders, Candida may also protect against immune pathologies highlighting a more intriguing role in the gut. Herein, we postulated that a state of chronic inflammation associated with microbial dysbiosis and leaky gut are favorable conditions that promote C. albicans pathogenicity eventually contributing to CD pathology via a mast cells (MC)-IL-9 axis. However, the restoration of immune and microbial homeostasis promotes a beneficial C. albicans-MC cross-talk favoring the attenuation of CD pathology to alleviate CD pathology and symptoms.

Antidiabetic action of the Chinese formula Shouhuitongbian and the underlying mechanism associated with alteration of gut microbiota

BACKGROUND

The prevalence and incidence of type 2 diabetes mellitus (T2DM) have dramatically increased. The intestinal flora and its derived metabolites are demonstrated to play vital roles in the etiology and onset of T2DM. Shouhuitongbian (SHTB) is a traditional Chinese formula to treat constipation. SHTB is composed of seven herbs and components of Colla corii asini (CCA) that are obtained from the hide of Equus asinus L.. Some of herbs in SHTB such as Aloe vera (L.) Burm.f., Cassia obtusifolia L., fruits of Lycium barbarum L., and Citrus aurantium L. have shown to improve insulin resistance (IR) and T2DM in early reports. We hypothesized that SHTB composed of these herbs has antidiabetic effects. The antidiabetic efficacy and mechanism of action of SHTB have not been previously reported.

HYPOTHESIS/PURPOSE

To demonstrate the antidiabetic effect and elucidate the underlying mechanisms of SHTB from the perspective of gut microbiota.

STUDY DESIGN

The main compounds were identified and quantified by high-performance liquid chromatography (HPLC)-mass spectrometry analysis. High fat diet (HFD)-fed mice and db/db mice were used to assess the antidiabetic effects and the mechanism of SHTB. The underlying mechanisms were evaluated by enzyme-linked immunosorbent assay (ELISA), western blot analysis, quantitative real time polymerase chain reaction (qPCR) analysis, 16S rRNA high-throughput sequencing, and targeted metabolome analysis.

METHODS

HFD-fed mice and db/db mice were orally treated with the standard positive drug metformin (100 mg/kg/d) and with SHTB (200 and 100 mg/kg/d), which was chemically characterized according to the European Medicine Agency (EMA) guidelines. The beneficial effects of SHTB were studied by homeostasis model assessment of insulin resistance (HOMA-IR) index, oral glucose tolerance test (OGTT), insulin tolerance test (ITT), total cholesterol (T-CHO), triglyceride (TG), and inflammation. Subsequently, 16S rDNA-based high-throughput pyrosequencing and GC-MS-based targeted metabolomics profiling were performed to analyze the gut microbiota composition and metabolites profile in the gut, respectively. Moreover, the mammalian target of rapamycin complex 1 (mTORC1) / insulin receptor substrate 1 (IRS-1) / phosphoinositide 3-kinase (PI3K) / protein kinase B (AKT) pathway was evaluated via qPCR and western blot.

RESULTS

Chemically characterized SHTB, in which six markers were quantified, effectively alleviated glucose intolerance and IR, ameliorated lipid metabolism dysfunction, and reduced inflammation. In addition, 16S rDNA sequencing found that SHTB reshaped the composition of intestinal flora, as indicated by the enrichment of Akkermansia and Parabacteroides in both HFD-fed and db/db mice. Moreover, SHTB enhanced the intestinal production of short-chain fatty acids (SCFAs) and branched short-chain fatty acids (BSCFAs), and reduced the levels of the fecal and circulating branched-chain amino acids (BCAAs). The IRS-1/PI3K/AKT signaling pathway was upregulated after treatment with SHTB.

CONCLUSION

Orally administration of SHTB effectively improved IR and reduced hyperglycemia in mice. Treatment with SHTB regulated the gut BCAAs-mTORC1/IRS-1/PI3K/AKT axis by enhancing the BCAAs catabolism in the gut, which attenuated the deleterious effect of BCAAs on the IRS-1 signaling pathway.

In vitro human gut microbiota fermentation of litchi pulp polysaccharides as affected by Lactobacillus pre-treatment

In this study, litchi polysaccharides were obtained from unfermented or fermented pulp by Lactobacillus fermentum (denoted as LP and LPF, respectively). The differences between LP and LPF in the colonic fermentation characteristics and modulatory of gut microbiota growth and metabolism were investigated with an in vitro fecal fermentation model. Results revealed that the strategies of gut bacteria metabolizing LP and LPF were different and LPF with lower molecular weight (Mw) was readily utilized by bacteria. The monosaccharide utilization sequence of each polysaccharide was Ara > Gla > GalA > GlcA ≈ Glu ≈ Man. Moreover, LPF promoted stronger proliferation of Bifidobacterium, Megamonas, Prevotella, and Bacteroides and higher SCFAs production (especially acetic and butyric acids) than LP. Correlation analysis further revealed that Mw could represent an essential structural feature of polysaccharides associated with its microbiota-regulating effect. Overall, Lactobacillus fermentation pre-treatment of litchi pulp promoted the fermentation characteristics and prebiotic activities of its polysaccharide.

Butyrate inhibits type 2 inflammation in eosinophilic chronic rhinosinusitis

Butyrate and other Short-chain fatty acids (SCFAs) are microbial metabolites from Bacteroides and Clostridium species that may suppress type 2 inflammation. However, the mechanisms of SCFAs in the nasal sinuses are not fully understood. We aimed to clarify the in vitro and in vivo roles of SCFAs in eosinophilic chronic rhinosinusitis (ECRS) pathophysiology. We investigated whether SCFAs induced changes in type 2 cytokines, IgE, and apoptosis and the roles of GPR41, GPR43, and histone deacetylase. Analysis of the control subjects demonstrated that butyrate of SCFAs effectively inhibited type 2 cytokine production in PBMCs, ILC2s, and CD4+ T cells and IgE production in CD19+ B cells. In annexin V analysis, butyrate also induced late apoptosis of PBMCs. The butyrate-induced inhibition of type 2 cytokines appeared involved in histone deacetylase inhibition but not in GPR41 or GPR43. In an analysis of ECRS in humans, butyrate inhibited type 2 cytokine production in PBMCs and nasal polyp-derived cells. The butyrate concentration in nasal lavage fluid was significantly decreased in ECRS patients compared to controls and non-ECRS patients. Our findings confirm that butyrate can inhibit type 2 inflammation and may be a potential therapeutic target for ECRS.

Acetate Abates Arsenic-Induced Male Reproductive Toxicity by Suppressing HDAC and Uric Acid-Driven Oxido-inflammatory NFkB/iNOS/NO Response in Rats

Arsenic is associated with male reproductive toxicity through histone deacetylation and oxido-inflammatory injury. Notwithstanding, short-chain fatty acids such as acetate exert anti-oxido-inflammatory activities and inhibit histone deacetylation. This study investigated the impact of acetate on arsenic-induced male reproductive toxicity. Forty eight adult male Wistar rats were allotted into any of these four groups (n = 12 rats per group): vehicle-treated, sodium acetate-treated, arsenic-exposed, and arsenic-exposed + sodium acetate-treated. The results revealed that arsenic exposure prolonged the latencies of mount, intromission, and ejaculation and reduced the frequencies of mount, intromission, and ejaculation, as well as mating and fertility indices, litter size and weight, anogenital distance, anogenital index, and survival rate in male F1 offspring at weaning. Also, arsenic reduced the circulating levels of gonadotropin-releasing hormone, luteinizing hormone, follicle-stimulating hormone, and testosterone and testicular 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase activities. In addition, arsenic reduced the daily and total spermatid production, sperm count, motility, and viability but increased the percentage of sperm cells with abnormal morphology. Furthermore, arsenic increased testicular xanthine oxidase activity, uric acid, and malondialdehyde levels, and reduced glutathione content, superoxide dismutase and catalase activities, total antioxidant capacity, and Nrf2 level. More so, arsenic exposure increased testicular iNOS activity and nitric oxide (NO), TNF-α, IL-1β, IL-6, and NFkB levels as well as Bax, caspase 9, and caspase 3 activities, and reduced Bcl-2. These findings were associated with arsenic-induced increase in testicular arsenic concentration, histone deacetylase activity, and reduced testicular weight. Histopathological examination revealed that arsenic also disrupted testicular histoarchitecture, which was accompanied by altered testicular planimetry and reduced spermatogenic cells. Notwithstanding, sodium acetate alleviated arsenic-induced sexual dysfunction as well as biochemical and histological alterations. These were accompanied acetate-driven downregulation of histone deacetylase (HDAC) activity. Succinctly, acetate attenuated arsenic-induced male reproductive toxicity by suppressing HDAC and uric acid-driven oxido-inflammatory NFkB/iNOS/NO response.

The gut microbiota in adults with chronic intestinal failure

OBJECTIVE

Fecal microbiota was investigated in adult patients with chronic intestinal failure (CIF) due to short bowel syndrome (SBS) with jejunocolonic anastomosis (SBS-2). Few or no data are available on SBS with jejunostomy (SBS-1) and CIF due to intestinal dysmotility (DYS) or mucosal disease (MD). We profiled the fecal microbiota of various pathophysiological mechanisms of CIF.

METHODS

Cross-sectional study on 61 adults with CIF (SBS-1 30, SBS-2 17, DYS 8, MD 6). Fecal samples were collected and profiled by 16S rRNA amplicon sequencing. Healthy controls (HC) were selected from pre-existing cohorts, matched with patients by sex and age.

RESULTS

Compared to HC, SBS-1, SBS-2 and MD patients showed lower alpha diversity; no difference was found for DYS. In beta diversity analysis, SBS-1, SBS-2 and DYS groups segregated from HC and from each other. Taxonomically, the CIF groups differed from HC even at the phylum level. In particular, CIF patients' microbiota was dominated by Lactobacillaceae and Enterobacteriaceae, while depleted in typical health-associated taxa belonging to Lachnospiraceae and Ruminococcaceae. Notably, compositional peculiarities of the CIF groups emerged. Furthermore, in the SBS groups, the microbiota profile differed according to the amount of parenteral nutrition required and the duration of CIF.

CONCLUSIONS

CIF patients showed marked intestinal dysbiosis with microbial signatures specific to the pathophysiological mechanism of CIF as well as to the severity and duration of SBS.

Maternal or post-weaning dietary fructo-oligosaccharide supplementation reduces stillbirth rate of sows and diarrhea of weaned piglets

Fructo-oligosaccharides (FOS) are well-known prebiotics that have the potential to improve sow reproductive performance and increase piglet growth. However, previous studies were observed in sole FOS-supplemented diets of sows or weaned piglets and did not consider the sow-to-piglet transfer effect on the performance and diarrhea rate of weaned piglets. This study explores the effects of dietary FOS supplementation on the reproductive performance of sows, and the effects of FOS supplementation at different stages on the growth performance and diarrhea rate of weaned piglets. A split-plot experimental design was used with sow diet effect in the whole plot and differing piglet diet effect in the subplot. Fifty-two multiparous sows (223.24 ± 14.77 kg) were randomly divided into 2 groups (0 or 0.2% FOS). The experiment lasted from day 85 of gestation to day 21 of lactation. Reproductive performance, glucose tolerance, placental angiogenesis, and intestinal flora of sows were assessed. At weaning, 192 weaned piglets were grouped in 2 × 2 factorial designs, with the main effects of FOS supplemental level of sow diet (0 and 0.2%), and FOS supplemental level of weaned piglet diet (0 and 0.2%), respectively. The growth performance and diarrhea rate of the weaned piglets were analyzed during a 28-d experiment. Maternal dietary supplementation of FOS was shown to reduce the stillbirth and invalid piglet rates (P < 0.05), improve the insulin sensitivity (P < 0.05) and fecal scores (P < 0.05) of sows, increase the abundance of Akkermansia muciniphila (P = 0.016), decrease the abundance of Escherichia coli (P = 0.035), and increase the isovalerate content in feces (P = 0.086). Meanwhile, the placental angiogenesis marker CD31 expression was increased in sows fed FOS diet (P < 0.05). Moreover, maternal and post-weaning dietary FOS supplementation reduced the diarrhea rate of weaned piglets (P < 0.05) and increased the content of short-chain fatty acids in feces (P < 0.05). Furthermore, only post-weaning dietary FOS supplementation could improve nutrient digestibility of weaned piglets (P < 0.05). Collectively, FOS supplementation in sows can reduce stillbirth rate, perinatal constipation, and insulin resistance, as well as improve placental vascularization barrier. Additionally, maternal and post-weaning dietary FOS supplementation reduced the diarrhea rate of weaned piglets, but only FOS supplementation in piglets alone at weaning stage could improve their nutrient digestibility.

Chronotropic and vasoactive properties of the gut bacterial short-chain fatty acids in larval zebrafish

Short-chain fatty acids (SCFAs) produced by the gut bacteria have been associated with cardiovascular dysfunction in humans and rodents. However, studies exploring effects of SCFAs on cardiovascular parameters in the zebrafish, an increasingly popular model in cardiovascular research, remain limited. Here, we performed fecal bacterial 16S sequencing and gas chromatography/mass spectrometry (GC-MS) to determine the composition and abundance of gut microbiota and SCFAs in adult zebrafish. Following this, the acute effects of major SCFAs on heart rate and vascular tone were measured in anesthetized zebrafish larvae using fecal concentrations of butyrate, acetate, and propionate. Finally, we investigated if coincubation with butyrate may lessen the effects of angiotensin II (ANG II) and phenylephrine (PE) on vascular tone in anesthetized zebrafish larvae. We found that the abundance in Proteobacteria, Firmicutes, and Fusobacteria phyla in the adult zebrafish resembled those reported in rodents and humans. SCFA levels with highest concentration of acetate (27.43 µM), followed by butyrate (2.19 µM) and propionate (1.65 µM) were observed in the fecal samples of adult zebrafish. Immersion in butyrate and acetate produced a ∼20% decrease in heart rate (HR), respectively, with no observed effects of propionate. Butyrate alone also produced an ∼25% decrease in the cross-sectional width of the dorsal aorta (DA) at 60 min (*P < 0.05), suggesting compensatory vasoconstriction, with no effects of either acetate or propionate. In addition, butyrate significantly alleviated the decrease in DA cross-sectional width produced by both ANG II and PE. We demonstrate the potential for zebrafish in investigation of host-microbiota interactions in cardiovascular health.NEW & NOTEWORTHY We highlight the presence of a core gut microbiota and demonstrate in vivo short-chain fatty acid production in adult zebrafish. In addition, we show cardio-beneficial vasoactive and chronotropic properties of butyrate, and chronotropic properties of acetate in anesthetized zebrafish larvae.

Rosemary leaf powder improves egg quality, antioxidant status, gut barrier function, and cecal microbiota and metabolites of late-phase laying hens

This study sought to determine the effects of rosemary leaf powder (RP) on laying performance, egg quality, serum indices, gut barrier function, and cecal microbiota and metabolites of late-phase laying hens. A total of 84 "Jing Tint 6" laying hens at 65-week old were randomly divided into 2 groups and fed either a basal diet (CON) or a basal diet supplemented with 0.3% RP. Our study revealed that RP improved the Haugh unit and decreased yolk n-6/n-3 polyunsaturated fatty acid (PUFA) ratio of laying hens, increased serum superoxide dismutase (SOD), jejunal activities of SOD and catalase (CAT), and jejunal zonula occludens-1 (ZO-1) expression, as well as decreased serum tumor necrosis factor-α (TNF-α) level and jejunal TNF-α mRNA expression. Rosemary leaf powder markedly enhanced (P < 0.05) cecal abundances of Rikenellaceae, Rikenellaceae_RC9_gut_group, and Turicibacter, tended to promote (P = 0.076) butyrate concentration, and reduced (P < 0.05) cecal abundances of Erysipelatoclostridiaceae, Sutterellaceae, Fusobacteriaceae, Campylobacteraceae, Sutterella, Campylobacter, and Fusobacterium, which were closely linked with Haugh unit, yolk n-6/n-3 PUFA ratio, serum SOD and TNF-α. In addition, RP altered the metabolic functions of cecal microbiota and enhanced the abundances of butyrate-synthesizing enzymes, including lysine 2,3-aminomutase, β-lysine 5,6-aminomutase, and 3-oxoacid CoA-transferase. Together, 0.3% RP has the potential to enhance egg quality by partially modulating serum antioxidant status, jejunal barrier function, and cecal microbiota structure and metabolites, indicating that RP could be considered a promising feed additive to promote the production performance of late-phase laying hens.

Engineered microorganisms: A new direction in kidney stone prevention and treatment

Numerous studies have shown that intestinal and urinary tract flora are closely related to the formation of kidney stones. The removal of probiotics represented by lactic acid bacteria and the colonization of pathogenic bacteria can directly or indirectly promote the occurrence of kidney stones. However, currently existing natural probiotics have limitations. Synthetic biology is an emerging discipline in which cells or living organisms are genetically designed and modified to have biological functions that meet human needs, or even create new biological systems, and has now become a research hotspot in various fields. Using synthetic biology approaches of microbial engineering and biological redesign to enable probiotic bacteria to acquire new phenotypes or heterologous protein expression capabilities is an important part of synthetic biology research. Synthetic biology modification of microorganisms in the gut and urinary tract can effectively inhibit the development of kidney stones by a range of means, including direct degradation of metabolites that promote stone production or indirect regulation of flora homeostasis. This article reviews the research status of engineered microorganisms in the prevention and treatment of kidney stones, to provide a new and effective idea for the prevention and treatment of kidney stones.

Gut Microbiome and Polycystic Ovary Syndrome: Interplay of Associated Microbial-Metabolite Pathways and Therapeutic Strategies

Polycystic ovary syndrome (PCOS) is a multifaceted disease with an intricate etiology affecting reproductive-aged women. Despite attempts to unravel the pathophysiology, the molecular mechanism of PCOS remains unknown. There are no effective or suitable therapeutic strategies available to ameliorate PCOS; however, the symptoms can be managed. In recent years, a strong association has been found between the gut microbiome and PCOS, leading to the formulation of novel ideas on the genesis and pathological processes of PCOS. Further, gut microbiome dysbiosis involving microbial metabolites may trigger PCOS symptoms via many mechanistic pathways including those associated with carbohydrates, short-chain fatty acids, lipopolysaccharides, bile acids, and gut-brain axis. We present the mechanistic pathways of PCOS-related microbial metabolites and therapeutic opportunities available to treat PCOS, such as prebiotics, probiotics, and fecal microbiota therapy. In addition, the current review highlights the emerging treatment strategies available to alleviate the symptoms of PCOS.

The impact of high-salt diet on asthma in humans and mice: Effect on specific T-cell signatures and microbiome

BACKGROUND

The rise in asthma has been linked to different environmental and lifestyle factors including dietary habits. Whether dietary salt contributes to asthma incidence, remains controversial. We aimed to investigate the impact of higher salt intake on asthma incidence in humans and to evaluate underlying mechanisms using mouse models.

METHODS

Epidemiological research was conducted using the UK Biobank Resource. Data were obtained from 42,976 participants with a history of allergies. 24-h sodium excretion was estimated from spot urine, and its association with asthma incidence was assessed by Cox regression, adjusting for relevant covariates. For mechanistic studies, a mouse model of mite-induced allergic airway inflammation (AAI) fed with high-salt diet (HSD) or normal-salt chow was used to characterize disease development. The microbiome of lung and feces (as proxy for gut) was analyzed via 16S rRNA gene based metabarcoding approach.

RESULTS

In humans, urinary sodium excretion was directly associated with asthma incidence among females but not among males. HSD-fed female mice displayed an aggravated AAI characterized by increased levels of total IgE, a TH2-TH17-biased inflammatory cell infiltration accompanied by upregulation of osmosensitive stress genes. HSD induced distinct changes in serum short chain fatty acids and in both gut and lung microbiome, with a lower Bacteroidetes to Firmicutes ratio and decreased Lactobacillus relative abundance in the gut, and enriched members of Gammaproteobacteria in the lung.

CONCLUSIONS

High dietary salt consumption correlates with asthma incidence in female adults with a history of allergies. Female mice revealed HSD-induced T-cell lung profiles accompanied by alterations of gut and lung microbiome.

The impact of depression-mediated gut microbiota composition on Irritable Bowel Syndrome: A Mendelian study

OBJECTIVE

This study uses a two-sample Mendelian randomization (MR) analysis to delineate the causal influence of gut microbiota on the occurrence of irritable bowel syndrome (IBS), concurrently assessing the potential mediating function of depression within this framework.

METHODS

Several two-sample MR methods were used to assess the causal repercussions of gut microbiota on the onset of both IBS and depression. Following this, gut microbiota and depression, which demonstrated notable causal associations, were integrated as exposure variables in a multivariable Mendelian randomization (MVMR) framework to construct a model encompassing gut microbiota, depression, and IBS. Mediation effects were assessed by examining the indirect pathway of gut microbiota → depression → IBS.

RESULTS

Two-sample MR analysis unveiled a statistically significant causal association (P < 0.05) between specific bacterial group within the gut microbiota, notably p_Actinobacteria(OR = 0.829225), c_Clostridia(OR = 0.798897), s_Desulfovibrio_piger(OR = 1.163912), g_Streptococcus(OR = 1.132735), c_Actinobacteria(OR = 0.829224), and the onset of IBS. In the MVMR analysis, the relationship between depression and IBS was significant across Model 3, Model 7, Model 8, and Model 13 (P < 0.05). Assessment of mediation effects revealed that c_Clostridia and o_Clostridiales indirectly impacted IBS through depression, with masking effect ratios of 168.46 % and 168.44 %, respectively.

CONCLUSION

These findings underscore a resilient causal association between the composition of gut microbiota and the initiation of IBS. Furthermore, depression serves as a mediator for particular groups of gut bacteria, thereby contributing to the development of IBS. These observations imply that interventions targeting mental health may potentially alleviate the risk of IBS onset attributable to adverse configurations of gut microbiota.

Qingzhuan dark tea polysaccharides-zinc alleviates dextran sodium sulfate-induced ulcerative colitis

BACKGROUND

Qingzhuan dark tea polysaccharides (QDTP) have been complexed with Zinc (Zn) to form the Qingzhuan dark tea polysaccharides-Zinc (QDTP-Zn) complex. The present study investigated the protective effects of QDTP-Zn on ulcerative colitis (UC) in mice. The UC mouse model was induced using dextran sodium sulfate (DSS), followed by oral administration of QDTP-Zn (0.2 and 0.4 g kg-1 day-1).

RESULTS

QDTP-Zn demonstrated alleviation of UC symptoms in mice, as evidenced by a decrease in disease activity index scores. QDTP-Zn also regulated colon tissue injury by upregulating ZO-1 and occludin protein expression, at the same time as downregulating tumor necrosis factor-α and interleukin-6β levels. Furthermore, QDTP-Zn induced significant alterations in the abundance of bacteroidetes and firmicutes and notably increased levels of short-chain fatty acids (SCFAs), particularly acetic acid, propionic acid, and butyric acid.

CONCLUSION

In summary, QDTP-Zn exhibits therapeutic potential in alleviating enteritis by fortifying the colonic mucosal barrier, mitigating inflammation and modulating intestinal microbiota and SCFAs levels. Thus, QDTP-Zn holds promise as a functional food for both the prevention and treatment of UC. © 2024 Society of Chemical Industry.

Short-chain fatty acids: bridges between diet, gut microbiota, and health

In recent years, gut microbiota has become a hot topic in the fields of medicine and life sciences. Short-chain fatty acids (SCFAs), the main metabolites of gut microbiota produced by microbial fermentation of dietary fiber, play a vital role in healthy and ill hosts. SCFAs regulate the process of metabolism, immune, and inflammation and have therapeutic effects on gastrointestinal and neurological disorders, as well as antitumor properties. This review summarized the production, distribution, and molecular mechanism of SCFAs, as well as their mechanisms of action in healthy and ill hosts. In addition, we also emphasized the negative effects of SCFAs, aiming to provide the public with a more comprehensive understanding of SCFAs.

Alginate oligosaccharide assimilation by gut microorganisms and the potential role in gut inflammation alleviation

Dietary fiber metabolism by gut microorganisms plays important roles in host physiology and health. Alginate, the major dietary fiber of daily diet seaweeds, is drawing more attention because of multiple biological activities. To advance the understanding of alginate assimilation mechanism in the gut, we show the presence of unsaturated alginate oligosaccharides (uAOS)-specific alginate utilization loci (AUL) in human gut microbiome. As a representative example, a working model of the AUL from the gut microorganism Bacteroides clarus was reconstructed from biochemistry and transcriptome data. The fermentation of resulting monosaccharides through Entner-Doudoroff pathway tunes the metabolism of short-chain fatty acids and amino acids. Furthermore, we show that uAOS feeding protects the mice against dextran sulfate sodium-induced acute colitis probably by remodeling gut microbiota and metabolome.

IMPORTANCE

Alginate has been included in traditional Chinese medicine and daily diet for centuries. Recently discovered biological activities suggested that alginate-derived alginate oligosaccharides (AOS) might be an active ingredient in traditional Chinese medicine, but how these AOS are metabolized in the gut and how it affects health need more information. The study on the working mechanism of alginate utilization loci (AUL) by the gut microorganism uncovers the role of unsaturated alginate oligosaccharides (uAOS) assimilation in tuning short-chain fatty acids and amino acids metabolism and demonstrates that uAOS metabolism by gut microorganisms results in a variation of cell metabolites, which potentially contributes to the physiology and health of gut.

Relationship between Rumen Microbial Differences and Phenotype Traits among Hu Sheep and Crossbred Offspring Sheep

This experiment was conducted to investigate the effect of three-way hybrid sheep and Hu sheep on serum indicators, rumen fermentation, rumen enzyme activity, and microorganisms in sheep. Healthy and similar birth weights from three groups (Hu, n = 11; Charolais × Australian White × Hu, CAH, n = 11; Charolais × Dorper × Hu, CDH, n = 11) were selected to be fed by the ewes until 45 days of age. Subsequently, they were weaned intensively and underwent short-term fattening for 3 months along with selected male lambs fed intensively. During this period, they were fed and watered ad libitum. Blood and rumen fluid were collected and analyzed for serum indicators and rumen fluid microorganisms, enzyme activity, and VFA, respectively, at the end of the fattening period. Compared with Hu lamb, the offspring of the three-way hybrid lamb showed significant improvements in body weight, serum lactate dehydrogenase, and creatinine content. However, there was no significant effect on serum immunity and antioxidant indices. In addition, the rumen fluid volatile fatty acid (VFA) molar concentration and microcrystalline cellulose and lipase content were significantly lower in the three-way hybrid lamb compared to Hu lamb, but β-glucosidase, amylase, pepsin, and VFA molar ratio were not significantly affected. Subsequently, 16S rRNA sequencing diversity analysis revealed that three-way hybrid lamb significantly increased rumen microbial ACE and Chao1 indices compared to Hu lamb. Meanwhile, the abundance of Verrucomicrobiota and Synergistota significantly increased at the phylum level. Correlation analysis showed that Prevotella had the highest proportion, while Rikenellaceae_RC9_gut_group correlated most closely with others genus. The microbial communities isovaleric acid molar concentration and proportion were strongly correlated. In addition, there were significant differences in correlations between microbial communities and isobutyric acid, butyric acid and valeric acid content, and their molar proportion, but they were not significantly correlated with digestive enzymes. From the functional enrichment analysis, it was found that hybrid progeny were mainly enriched in the pyruvate metabolism, microbial metabolism in diverse environments, carbon metabolism, and quorum sensing pathways. In contrast, the Hu sheep were primarily enriched in the cysteine and methionine, amino sugar and nucleotide sugar, and biosynthesis of secondary metabolite pathways. These results suggest that hybridization can play a role in regulating organismal metabolism and improve animal production performance by influencing the structure and characteristics of microbial communities.

Metformin-induced changes of the gut microbiota in patients with type 2 diabetes mellitus: results from a prospective cohort study

BACKGROUND

The influence of the microbiota on hypoglycemic agents is becoming more apparent. The effects of metformin, a primary anti-diabetes drug, on gut microbiota are still not fully understood.

RESEARCH DESIGN AND METHODS

This prospective cohort study aims to investigate the longitudinal effects of metformin on the gut microbiota of 25 treatment-naïve diabetes patients, each receiving a daily dose of 1500 mg. Microbiota compositions were analyzed at baseline, and at 1, 3, and 6 months of medication using 16S rRNA gene sequencing.

RESULTS

Prior to the 3-month period of metformin treatment, significant improvements were noted in body mass index (BMI) and glycemic-related parameters, such as fasting blood glucose (FPG) and hemoglobin A1c (HbA1c), alongside homeostasis model assessment indices of insulin resistance (HOMA-IR). At the 3-month mark of medication, a significant reduction in the α-diversity of the gut microbiota was noted, while β-diversity exhibited no marked variances throughout the treatment duration. The Firmicutes to Bacteroidetes ratio. markedly decreased. Metformin treatment consistently increased Escherichia-Shigella and decreased Romboutsia, while Pseudomonas decreased at 3 months. Fuzzy c-means clustering identified three longitudinal trajectory clusters for microbial fluctuations: (i) genera temporarily changing, (ii) genera continuing to decrease (Bacteroides), and (iii) genera continuing to increase(Lachnospiraceae ND3007 group, [Eubacterium] xylanophilum group, Romboutsia, Faecalibacterium and Ruminococcaceae UCG-014). The correlation matrix revealed associations between specific fecal taxa and metformin-related clinical parameters HbA1c, FPG, Uric Acid (UA), high-density lipoproteincholesterol (HDL-C), alanine aminotransferase (ALT), hypersensitive C-reactive protein (hs-CRP), triglyceride (TG) (P < 0.05). Metacyc database showed that metformin significantly altered 17 functional pathways. Amino acid metabolism pathways such as isoleucine biosynthesis predominated in the post-treatment group.

CONCLUSIONS

Metformin's role in glucose metabolism regulation may primarily involve specific alterations in certain gut microbial species rather than an overall increase in microbial species diversity. This may suggest gut microbiota targets in future studies on metabolic abnormalities caused by metformin.

Chemical interplay between gut microbiota and epigenetics: Implications in circadian biology

Circadian rhythms are intrinsic molecular mechanisms that synchronize biological functions with the day/night cycle. The mammalian gut is colonized by a myriad of microbes, collectively named the gut microbiota. The microbiota impacts host physiology via metabolites and structural components. A key mechanism is the modulation of host epigenetic pathways, especially histone modifications. An increasing number of studies indicate the role of the microbiota in regulating host circadian rhythms. However, the mechanisms remain largely unknown. Here, we summarize studies on microbial regulation of host circadian rhythms and epigenetic pathways, highlight recent findings on how the microbiota employs host epigenetic machinery to regulate circadian rhythms, and discuss its impacts on host physiology, particularly immune and metabolic functions. We further describe current challenges and resources that could facilitate research on microbiota-epigenetic-circadian rhythm interactions to advance our knowledge of circadian disorders and possible therapeutic avenues.

Compositional and functional analysis of the bacterial community of Mediterranean Leptosols under livestock grazing

The composition and functioning of soil bacterial communities, as well as their responses to multiple perturbations, are not well understood in the terrestrial ecosystems. Our study focuses on the bacterial community of erosive and poorly developed soils (Haplic Leptosols) in Mediterranean rangelands of Extremadura (W Spain) with different grazing intensities. Leptosols from similar natural conditions were selected and sampled at two depths to determine the soil properties as well as the structure and activity of bacterial communities. As grazing intensified, the soil C and N content increased, as did the number and diversity of bacteria, mainly of fast-growing lineages. Aridibacter, Acidobacteria Gp6 and Gp10, Gemmatimonas, and Segetibacter increased their abundance along the grazing-intensity gradient. Firmicutes such as Romboutsia and Turicibacter from livestock microbiome also increased. In functional terms, the KEGG pathways enriched in the soils with moderate and high grazing intensity were ABC transporters, DNA repair and recombination proteins, the two-component system, and the degradation of xenobiotics. All of these proved to be related to stronger cell division and response mechanisms to environmental stressors such as drought, warming, toxic substances, and nutrient deprivation. Consequently, the bacterial community was affected by grazing, but appeared to adapt and counteract the effects of a high grazing intensity. Therefore, a clearly detrimental effect of grazing was not detected in the bacterial community of the soils studied.

Human Breast Milk: The Role of Its Microbiota and Metabolites in Infant Health

This review explores the role of microorganisms and metabolites in human breast milk and their impact on neonatal health. Breast milk serves as both a primary source of nutrition for newborns and contributes to the development and maturation of the digestive, immunological, and neurological systems. It has the potential to reduce the risks of infections, allergies, and asthma. As our understanding of the properties of human milk advances, there is growing interest in incorporating its benefits into personalized infant nutrition strategies, particularly in situations in which breastfeeding is not an option. Future infant formula products are expected to emulate the composition and advantages of human milk, aligning with an evolving understanding of infant nutrition. The long-term health implications of human milk are still under investigation.

Fucoidan from Ascophyllum nodosum and Undaria pinnatifida attenuate SARS-CoV-2 infection in vitro and in vivo by suppressing ACE2 and alleviating inflammation

The global healthcare challenge posed by COVID-19 necessitates the continuous exploration for novel antiviral agents. Fucoidans have demonstrated antiviral activity. However, the underlying structure-activity mechanism responsible for the inhibitory activity of fucoidans from Ascophyllum nodosum (FUCA) and Undaria pinnatifida (FUCU) against SARS-CoV-2 remains unclear. FUCA was characterized as a homopolymer with a backbone structure of repeating (1 → 3) and (1 → 4) linked α-l-fucopyranose residues, whereas FUCU was a heteropolysaccharide composed of Fuc1-3Gal1-6 repeats. Furthermore, FUCA demonstrated significantly higher anti-SARS-CoV-2 activity than FUCU (EC50: 48.66 vs 69.52 μg/mL), suggesting the degree of branching rather than sulfate content affected the antiviral activity. Additionally, FUCA exhibited a dose-dependent inhibitory effect on ACE2, surpassing the inhibitory activity of FUCU. In vitro, both FUCA and FUCU treatments downregulated the expression of pro-inflammatory cytokines (IL-6, IFN-α, IFN-γ, and TNF-α) and anti-inflammatory cytokines (IL-10 and IFN-β) induced by viral infection. In hamsters, FUCA demonstrated greater effectiveness in attenuating lung and gastrointestinal injury and reducing ACE2 expression, compared to FUCU. Analysis of the 16S rRNA gene sequencing revealed that only FUCU partially alleviated the gut microbiota dysbiosis caused by SARS-CoV-2. Consequently, our study provides a scientific basis for considering fucoidans as poteintial prophylactic food components against SARS-CoV-2.

A Randomized Clinical Trial to Evaluate the Efficacy of an Oral Probiotic in Acne Vulgaris

The relevance of the gut microbiota in some skin inflammatory diseases, including acne vulgaris, has been emphasized. Probiotics could play a role in the modulation of the microbiota, improving the clinical course of this disease. A 12-week randomized, double-blind, placebo-controlled, clinical trial with patients aged 12 to 30 years with acne vulgaris was conducted. The study product was a capsule composed of the probiotic Lacticaseibacillus rhamnosus (CECT 30031) and the cyanobacterium Arthrospira platensis (BEA_IDA_0074B). Patients with improvement in the Acne Global Severity Scale were 10/34 (29.41%) in the placebo group compared with 20/40 (50%) in the probiotic group (p = 0.03). A significant reduction (p = 0.03) in the number of non-inflammatory acne lesions was observed in the probiotic group (-18.60 [-24.38 to -12.82]) vs the placebo group (-10.54 [-17.43 to -3.66]). Regarding the number of total  lesions, a reduction almost reaching statistical significance (p = 0.06) was observed in the probiotic group (-27.94 [-36.35 to -19.53]) compared with the placebo group (-18.31 [-28.21 to -8.41]). In addition, patients with improvement attending the Global Acne Grading System were 7/34 (20.58%) in the placebo group vs 17/40 (42.50%) in the probiotic group (p = 0.02). The number of adverse events was similar in both groups. The probiotic used in this study was effective and well tolerated, and it should be considered for acne vulgaris patients.

Quantitation of circulating short-chain fatty acids in small volume blood samples from animals and humans

BACKGROUND

The role of gut microbiota in human health has been intensively studied and more recently shifted from emphasis on composition towards function. Function is partly mediated through formed metabolites. Short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate as well as their branched analogues represent major products from gut fermentation of dietary fibre and proteins, respectively. Robust and high-throughput analysis of SCFAs in small volume blood samples have proven difficult. Major obstacles come from the ubiquitous presence of SCFAs that leads to contaminations and unstable analytical results because of the high volatility of these small molecules. Comprehensive and comparable data on the variation of SCFAs in blood samples from different blood matrices and mammal species including humans is lacking. Therefore, our aim was to develop and evaluate a stable and robust method for quantitation of 8 SCFAs and related fermentation products in small volume blood plasma samples and to investigate their variation in humans and different animal species.

RESULTS

Derivatization was a successful approach for measurement of SCFAs in biological samples but quenching of the derivatization reaction was crucial to obtain long-term stability of the derivatized analytes. In total 9 compounds (including succinic acid) were separated in 5 min. The method was linear over the range 0.6-3200 nM formic (FA), acetic (AA), 0.3-1600 nM propionic (PA), and 0.16-800 nM for butyric (BA)-, isobutyric (IBA)-, valeric (VA)-, isovaleric (IVA)-, succinic (SA) and caproic acid (CA). The precision ranged ≤12 % within days and ≤28 % between days (except for CA and VA) in three different plasma quality control (QC) samples (29 batches analyzed over 3 months). The extraction recovery was on average 94 % for the different SCFAs. Typical interquartile range (IQR) concentrations (μM) of SCFAs in human plasma samples were 168 μM (FA), 64 μM (AA), 2.2 μM (PA), 0.54 μM (BA), 0.66 μM (IBA), 0.18 μM (VA), 0.40 μM (IVA), and 0.34 μM (CA). In total, 55 samples per batch/day were successfully analyzed and in total 5380 human plasma samples measured over a 3-year timespan.

SIGNIFICANCE

The developed UHPLC-MS based method was suitable for measuring SCFAs in small blood volume samples and enabled robust quantitative data.

Global research progress of gut microbiota and epigenetics: bibliometrics and visualized analysis

Background

Gut microbiota is an important factor affecting host health. With the further study of the mechanism of gut microbiota, significant progress has been made in the study of the link between gut microbiota and epigenetics. This study visualizes the body of knowledge and research priorities between the gut microbiota and epigenetics through bibliometrics.

Methods

Publications related to gut microbiota and epigenetics were searched in the Web of Science Core Collection (WoSCC) database. Vosviewer 1.6.17 and CiteSpace 6.1.R2 were used for bibliometric analysis.

Results

WoSCC includes 460 articles from 71 countries. The number of publications on gut microbiota and epigenetics has increased each year since 2011. The USA, PEOPLES R CHINA, and ITALY are at the center of this field of research. The University of California System, Harvard University, and the University of London are the main research institutions. Li, X, Yu, Q, Zhang, S X are the top authors in this research field. We found that current research hotspots and frontiers include short-chain fatty acids (SCFA) play an important role in gut microbiota and epigenetic mechanisms, gut microbiota and epigenetics play an important role in host obesity, diet, and metabolism. Gut microbiota and epigenetics are closely related to colorectal cancer, breast cancer, and inflammatory bowel disease. At the same time, we found that gut microbiota regulates epigenetics through the gut-brain axis and has an impact on psychiatric diseases. Therefore, probiotics can regulate gut microbiota, improve lifestyle, and reduce the occurrence and development of diseases.

Conclusion

This is the first comprehensive and in-depth bibliometric study of trends and developments in the field of gut microbiota and epigenetics research. This study helps to guide the direction of research scholars in their current field of study.

High-throughput identification of gut microbiome-dependent metabolites

A significant hurdle that has limited progress in microbiome science has been identifying and studying the diverse set of metabolites produced by gut microbes. Gut microbial metabolism produces thousands of difficult-to-identify metabolites, which present a challenge to study their roles in host biology. In recent years, mass spectrometry-based metabolomics has become one of the core technologies for identifying small metabolites. However, metabolomics expertise, ranging from sample preparation to instrument use and data analysis, is often lacking in academic labs. Most targeted metabolomics methods provide high levels of sensitivity and quantification, while they are limited to a panel of predefined molecules that may not be informative to microbiome-focused studies. Here we have developed a gut microbe-focused and wide-spectrum metabolomic protocol using liquid chromatography-mass spectrometry and bioinformatic analysis. This protocol enables users to carry out experiments from sample collection to data analysis, only requiring access to a liquid chromatography-mass spectrometry instrument, which is often available at local core facilities. By applying this protocol to samples containing human gut microbial metabolites, spanning from culture supernatant to human biospecimens, our approach enables high-confidence identification of >800 metabolites that can serve as candidate mediators of microbe-host interactions. We expect this protocol will lower the barrier to tracking gut bacterial metabolism in vitro and in mammalian hosts, propelling hypothesis-driven mechanistic studies and accelerating our understanding of the gut microbiome at the chemical level.

Taking SCFAs produced by Lactobacillus reuteri orally reshapes gut microbiota and elicits antitumor responses

BACKGROUND

Colorectal cancer (CRC) incidence is increasing in recent years due to intestinal flora imbalance, making oral probiotics a hotspot for research. However, numerous studies related to intestinal flora regulation ignore its internal mechanisms without in-depth research.

RESULTS

Here, we developed a probiotic microgel delivery system (L.r@(SA-CS)2) through the layer-by-layer encapsulation technology of alginate (SA) and chitosan (CS) to improve gut microbiota dysbiosis and enhance anti-tumor therapeutic effect. Short chain fatty acids (SCFAs) produced by L.r have direct anti-tumor effects. Additionally, it reduces harmful bacteria such as Proteobacteria and Fusobacteriota, and through bacteria mutualophy increases beneficial bacteria such as Bacteroidota and Firmicutes which produce butyric acid. By binding to the G protein-coupled receptor 109A (GPR109A) on the surface of colonic epithelial cells, butyric acid can induce apoptosis in abnormal cells. Due to the low expression of GPR109A in colon cancer cells, MK-6892 (MK) can be used to stimulate GPR109A. With increased production of butyrate, activated GPR109A is able to bind more butyrate, which further promotes apoptosis of cancer cells and triggers an antitumor response.

CONCLUSION

It appears that the oral administration of L.r@(SA-CS)2 microgels may provide a treatment option for CRC by modifying the gut microbiota.

Supplementation with soluble or insoluble rice-bran fibers increases short-chain fatty acid producing bacteria in the gut microbiota in vitro

Introduction

Studies have shown that a diet high in fiber and prebiotics has a positive impact on human health due largely to the fermentation of these compounds by the gut microbiota. One underutilized source of fiber may be rice bran, a waste product of rice processing that is used most frequently as an additive to livestock feed but may be a good source of fibers and other phenolic compounds as a human diet supplement. Previous studies focused on specific compounds extracted from rice bran showed that soluble fibers extracted from rice bran can improve glucose response and reduce weight gain in mouse models. However, less is known about changes in the human gut microbiota in response to regular rice bran consumption.

Methods

In this study, we used a Simulator of the Human Intestinal Microbial Ecology (SHIME®) to cultivate the human gut microbiota of 3 different donors in conditions containing either soluble or insoluble fiber fractions from rice bran. Using 16S rRNA amplicon sequencing and targeted metabolomics via Gas Chromatography-Mass Spectrometry, we explored how gut microbial communities developed provided different supplemental fiber sources.

Results

We found that insoluble and soluble fiber fractions increased short-chain fatty acid production, indicating that both fractions were fermented. However, there were differences in response between donors, for example the gut microbiota from donor 1 increased acetic acid production with both fiber types compared with control; whereas for donors 2 and 3, butanoic acid production increased with ISF and SF supplementation. Both soluble and insoluble rice bran fractions increased the abundance of Bifidobacterium and Lachnospiraceae taxa.

Discussion

Overall, analysis of the effect of soluble and insoluble rice bran fractions on the human in vitro gut microbiota and the metabolites produced revealed individually variant responses to these prebiotics.

Functional characterization of helminth-associated Clostridiales reveals covariates of Treg differentiation

BACKGROUND

Parasitic helminths influence the composition of the gut microbiome. However, the microbiomes of individuals living in helminth-endemic regions are understudied. The Orang Asli, an indigenous population in Malaysia with high burdens of the helminth Trichuris trichiura, display microbiotas enriched in Clostridiales, an order of spore-forming obligate anaerobes with immunogenic properties. We previously isolated novel Clostridiales that were enriched in these individuals and found that a subset promoted the Trichuris life cycle. In this study, we aimed to further characterize the functional properties of these bacteria.

RESULTS

Clostridiales isolates were profiled for their ability to perform 57 enzymatic reactions and produce short-chain fatty acids (SCFAs) and hydrogen sulfide, revealing that these bacteria were capable of a range of activities associated with metabolism and host response. Consistent with this finding, monocolonization of mice with individual isolates identified bacteria that were potent inducers of regulatory T-cell (Treg) differentiation in the colon. Comparisons between variables revealed by these studies identified enzymatic properties correlated with Treg induction and Trichuris egg hatching.

CONCLUSION

We identified Clostridiales species that are sufficient to induce high levels of Tregs. We also identified a set of metabolic activities linked with Treg differentiation and Trichuris egg hatching mediated by these newly isolated bacteria. Altogether, this study provides functional insights into the microbiotas of individuals residing in a helminth-endemic region. Video Abstract.

Intestinal metabolite xylulose inhibits colorectal cancer by inducing apoptosis through the MAPK signalling pathway

BACKGROUND

The intestinal metabolites are involved in the initiation, progression and metastasis of colorectal cancer (CRC). They are a potential source of agents for cancer therapy. Our previous study identified altered faecal metabolites between CRC patients and healthy volunteers. However, no specific metabolite was clearly illustrated for CRC therapy.

RESULTS

We found that the level of xylulose was lower in the stools of CRC patients than in those of healthy volunteers. Xylulose inhibited cell growth without affecting the cell cycle by inducing apoptosis in CRC cells, which was evidenced by increased expression of the proapoptotic proteins C-PARP and C-Caspase3 and decreased expression of the antiapoptotic protein BCL-2 in CRC cells. Mechanistically, xylulose reduced the activity of the MAPK signalling pathway, represented by reduced phosphorylation of JNK, ERK, and P38. Furthermore, an ALI model was used to show the tumour killing ability of xylulose on human CRC spheres, as well as human colorectal adenoma (AD) spheres.

CONCLUSION

Xylulose inhibits CRC growth by inducing apoptosis through attenuation of the MAPK signalling pathway. These results suggest that xylulose may serve as an effective agent for CRC therapy.

Study on the ameliorative effect of honeysuckle on DSS-induced ulcerative colitis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Honeysuckle, first documented in the Miscellaneous Records of Famous Physicians, is known for its ability to expel toxin and cool blood to stop diarrhea. Modern pharmacological research has shown that honeysuckle has anti-inflammatory, antibacterial, antioxidant, and immune-regulating effects and is widely used in clinical practice. However, the effect of honeysuckle on ulcerative colitis (UC) is still not fully understood, which presents challenges for quality control, research and development.

AIM OF THE STUDY

This study aimed to determine the anti-inflammatory properties and mechanism of action of aqueous extracts of honeysuckle in the treatment of ulcerative colitis.

MATERIALS AND METHODS

The dextran sodium sulfate (DSS) induced-ulcerative colitis mouse model was established, and the mice were divided into five groups: the control group, the model group, and the low, medium, and high dose honeysuckle treatment groups.

RESULTS

All dose groups of honeysuckle were found to significantly reduce IL-6 and TNF-α levels and regulate DSS-induced mRNA levels of CLDN4, COX-2, IL-6, INOS, MUC-2, occludin and NLRP3. The high-dose group displayed the most effective inhibition, and a differentially expressed mRNA detection indicated abnormal mRNA expression. The 16sRNA sequencing revealed that the honeysuckle was able to significantly upregulate the abundance of beneficial bacteria and downregulate the abundance of harmful bacteria. The study of short-chain fatty acids revealed that the levels of acetic, propionic, isobutyric, valeric and isovaleric acids were significantly increased after administering honeysuckle at medium and high doses.

CONCLUSION

Honeysuckle reduces the production of pro-inflammatory cytokines, increases the content of short-chain fatty acids and restores the intestinal ecological balance, resulting in better therapeutic effects.

Riboswitch Distribution in the Human Gut Microbiome Reveals Common Metabolite Pathways

Riboswitches are widely distributed, conserved RNAs which regulate metabolite levels in bacterial cells through direct, noncovalent binding of their cognate metabolite. Various riboswitch families are highly enriched in gut bacteria, suggestive of a symbiotic relationship between the host and bacteria. Previous studies of the distribution of riboswitches have examined bacterial taxa broadly. Thus, the distribution of riboswitches associated with bacteria inhabiting the intestines of healthy individuals is not well understood. To address these questions, we survey the gut microbiome for riboswitches by including an international database of prokaryotic genomes from the gut samples. Using Infernal, a program that uses RNA-specific sequence and structural features, we survey this data set using existing riboswitch models. We identify 22 classes of riboswitches with vitamin cofactors making up the majority of riboswitch-associated pathways. Our finding is reproducible in other representative databases from the oral as well as the marine microbiomes, underscoring the importance of thiamine pyrophosphate, cobalamin, and flavin mononucleotide in gene regulation. Interestingly, riboswitches do not vary significantly across microbiome representatives from around the world despite major taxonomic differences; this suggests an underlying conservation. Further studies elucidating the role of bacterial riboswitches in the host metabolome are needed to illuminate the consequences of our finding.

Fermented dietary fiber from soy sauce residue exerts antidiabetic effects through regulating the PI3K/AKT signaling pathway and gut microbiota-SCFAs-GPRs axis in type 2 diabetic mellitus mice

The gut plays a crucial role in the development and progression of metabolic disorders, particularly in relation to type 2 diabetes mellitus (T2DM). While a high intake of dietary fiber is inversely associated with the risk of T2DM, the specific effects of various dietary fibers on T2DM are not fully understood. This study investigated the anti-diabetic properties of fermented dietary fiber (FDF) derived from soy sauce residue in T2DM mice, demonstrating its ability to lower blood glucose levels and ameliorate insulin resistance. Our findings revealed that FDF could enhance hepatic glucose metabolism via the IRS-1/PI3K/AKT/mTOR pathway. Additionally, the anti-diabetic effect of FDF was correlated with alterations in gut microbiota composition in T2DM mice, promoting a healthier gut environment. Specifically, FDF increased the abundance of beneficial flora such as Dubosiella, Butyricimonas, Lachnospiraceae_NK4A136_group, Lactobacillus and Osillibacter, while reducing harmful bacteria including Bilophila, Parabacteroides and Enterorhabdus. Further analysis of microbial metabolites, including short-chain fatty acids (SCFAs) and bile acids (BAs), provided evidence of FDF's regulatory effects on cecal contents in T2DM mice. Importantly, FDF treatment significantly restored the G-protein-coupled receptors (GPRs) expression in the colon of T2DM mice. In conclusion, our study suggests that the anti-diabetic effects of FDF are associated with the regulation of both the liver-gut axis and the gut microbiota-SCFAs-GPRs axis.

Dietary fiber and polyphenols from whole grains: effects on the gut and health improvements

Cereals are the main source of energy in the human diet. Compared to refined grains, whole grains retain more beneficial components, including dietary fiber, polyphenols, proteins, vitamins, and minerals. Dietary fiber and bound polyphenols (biounavailable) in cereals are important active substances that can be metabolized by the gut microorganisms and affect the intestinal environment. There is a close relationship between the gut microbiota structures and various disease phenotypes, although the consistency of this link is affected by many factors, and the specific mechanisms are still unclear. Remodeling unfavorable microbiota is widely recognized as an important way to target the gut and improve diseases. This paper mainly reviews the interaction between the gut microbiota and cereal-derived dietary fiber and polyphenols, and also summarizes the changes to the gut microbiota and possible molecular mechanisms of related glycolipid metabolism. The exploration of single active ingredients in cereals and their synergistic health mechanisms will contribute to a better understanding of the health benefits of whole grains. It will further help promote healthier whole grain foods by cultivating new varieties with more potential and optimizing processing methods.

Neutrophils in pancreatic ductal adenocarcinoma: bridging preclinical insights to clinical prospects for improved therapeutic strategies

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by a dismal five-year survival rate of less than 10%. Neutrophils are key components of the innate immune system, playing a pivotal role in the PDAC immune microenvironment.

AREAS COVERED

This review provides a comprehensive survey of the pivotal involvement of neutrophils in the tumorigenesis and progression of PDAC. Furthermore, it synthesizes preclinical and clinical explorations aimed at targeting neutrophils within the milieu of PDAC, subsequently proposing a conceptual framework to propel further inquiry focused on enhancing the therapeutic efficacy of PDAC through neutrophil-targeted strategies. PubMed and Web of Science databases were utilized for researching neutrophils in pancreatic cancer publications prior to 2024.

EXPERT OPINION

Neutrophils play roles in promoting tumor growth and metastasis in PDAC and are associated with poor prognosis. However, the heterogeneity and plasticity of neutrophils and their complex relationships with other immune cells and extracellular matrix also provide new insights for immunotherapy targeting neutrophils to achieve a better prognosis for PDAC.

Small Intestinal Bacterial Overgrowth (SIBO) and Twelve Groups of Related Diseases-Current State of Knowledge

The human gut microbiota creates a complex microbial ecosystem, characterized by its high population density, wide diversity, and complex interactions. Any imbalance of the intestinal microbiome, whether qualitative or quantitative, may have serious consequences for human health, including small intestinal bacterial overgrowth (SIBO). SIBO is defined as an increase in the number of bacteria (103-105 CFU/mL), an alteration in the bacterial composition, or both in the small intestine. The PubMed, Science Direct, Web of Science, EMBASE, and Medline databases were searched for studies on SIBO and related diseases. These diseases were divided into 12 groups: (1) gastrointestinal disorders; (2) autoimmune disease; (3) cardiovascular system disease; (4) metabolic disease; (5) endocrine disorders; (6) nephrological disorders; (7) dermatological diseases; (8) neurological diseases (9); developmental disorders; (10) mental disorders; (11) genetic diseases; and (12) gastrointestinal cancer. The purpose of this comprehensive review is to present the current state of knowledge on the relationships between SIBO and these 12 disease groups, taking into account risk factors and the causal context. This review fills the evidence gap on SIBO and presents a biological-medical approach to the problem, clearly showing the groups and diseases having a proven relationship with SIBO, as well as indicating groups within which research should continue to be expanded.

Lactobacillus acidophilus KBL409 protects against kidney injury via improving mitochondrial function with chronic kidney disease

PURPOSE

Recent advances have led to greater recognition of the role of mitochondrial dysfunction in the pathogenesis of chronic kidney disease (CKD). There has been evidence that CKD is also associated with dysbiosis. Here, we aimed to evaluate whether probiotic supplements can have protective effects against kidney injury via improving mitochondrial function.

METHODS

An animal model of CKD was induced by feeding C57BL/6 mice a diet containing 0.2% adenine. KBL409, a strain of Lactobacillus acidophilus, was administered via oral gavage at a dose of 1 × 109 CFU daily. To clarify the underlying mechanisms by which probiotics exert protective effects on mitochondria in CKD, primary mouse tubular epithelial cells stimulated with TGF-β and p-cresyl sulfate were administered with butyrate.

RESULTS

In CKD mice, PGC-1α and AMPK, key mitochondrial energy metabolism regulators, were down-regulated. In addition, mitochondrial dynamics shifted toward fission, the number of fragmented cristae increased, and mitochondrial mass decreased. These alterations were restored by KBL409 administration. KBL409 supplementation also improved defects in fatty acid oxidation and glycolysis and restored the suppressed enzyme levels involved in TCA cycle. Accordingly, there was a concomitant improvement in mitochondrial respiration and ATP production assessed by mitochondrial function assay. These favorable effects of KBL409 on mitochondria ultimately decreased kidney fibrosis in CKD mice. In vitro analyses with butyrate recapitulated the findings of animal study.

CONCLUSIONS

This study demonstrates that administration of the probiotic Lactobacillus acidophilus KBL409 protects against kidney injury via improving mitochondrial function.

Emerging role of gut microbiota in autoimmune diseases

Accumulating studies have indicated that the gut microbiota plays a pivotal role in the onset of autoimmune diseases by engaging in complex interactions with the host. This review aims to provide a comprehensive overview of the existing literatures concerning the relationship between the gut microbiota and autoimmune diseases, shedding light on the complex interplay between the gut microbiota, the host and the immune system. Furthermore, we aim to summarize the impacts and potential mechanisms that underlie the interactions between the gut microbiota and the host in autoimmune diseases, primarily focusing on systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, type 1 diabetes mellitus, ulcerative colitis and psoriasis. The present review will emphasize the clinical significance and potential applications of interventions based on the gut microbiota as innovative adjunctive therapies for autoimmune diseases.

The role of gut microbiota and probiotics in preventing, treating, and boosting the immune system in colorectal cancer

The gut microbiome plays a significant role in developing colorectal cancer (CRC). The gut microbiome usually acts as a protective barrier against harmful pathogens and infections in the intestine, while also regulating inflammation by affecting the human immune system. The gut microbiota and probiotics play a role not only in intestinal inflammation associated with tumor formation but also in regulating anti-cancer immune response. As a result, they associated with tumor progression and the effectiveness of anti-cancer therapies. Research indicates that gut microbiota and probiotics can be used as biomarkers to predict the impact of immunotherapy and enhance its efficacy in treating CRC by regulating it. This review examines the importance of gut microbiota and probiotics in the development and progression of CRC, as well as their synergistic impact on anti-cancer treatments.

Alleviative effects of sulfated polysaccharide from Ishige Okamurae against DSS-induced ulcerative colitis via inhibiting inflammation and modulating gut microbiota

A water-soluble polysaccharide from the brown alga Ishige Okamurae, designated IOP-0, was obtained by preparative anion-exchange and size-exclusion chromatography. Chemical and spectroscopic investigations revealed that IOP-0 was a sulfated fucoidan with a backbone primarily composed of 3-linked and 4-linked-L-fucose with sulfate groups at C-2/C-4 of the 3-linked-L-fucose. The protective effect of IOP-0 on ulcerative colitis was evaluated in this work. The results showed that IOP-0 could significantly alleviate the symptoms of ulcerative colitis by preventing weight loss, preserving the structure of intestinal tissues, and ameliorating the dysregulation of inflammatory cytokines (TNF-α, IL-6, and IL-10). Meanwhile, IOP-0 protected the colonic mucosal barrier by promoting the tight junction protein ZO-1 and occludin expression. In addition, IOP-0 was able to maintain intestinal homeostasis and improve intestinal function by regulating the gut microbiota and their metabolites, such as short-chain fatty acids (SCFAs). These results suggest that IOP-0 might be a potential dietary supplement for the prevention and treatment of ulcerative colitis.

The effect of canagliflozin on gut microbiota and metabolites in type 2 diabetic mice

BACKGROUND

Sodium glucose cotransporter 2 inhibitor (SGLT2i) represent a new type of hypoglycemic medicine that can cause massive loss of glucose from the urine, which have several benefits of reducing body weight and improving the prognosis of cardiovascular and kidney diseases. Although they are oral medicated hypoglycemic agents, their effects on the gut microbiome and function have been unclear.

OBJECTIVE

In order to describe the effects of canagliflozin on intestinal flora and metabolites, diabetic mice were randomized to receive canagliflozin or isoconcentration carboxymethylcellulose sodium by gavage for 8 weeks. Feces were collected for 16 S rRNA gene and LC-MS/MS analysis and enriched metabolic pathways through Kyoto Encyclopedia of Genes and Genomes (KEGG). Liver, muscle, intestinal, fat were collected for qRT-PCR according to KEGG enriched metabolic pathways.

RESULTS

Our results showed that canagliflozin significantly increased GLP-1 level and impacted on the composition of gut microbiota and metabolites. It mainly increased Muribaculum, Ruminococcaceae_UCG_014, Lachnospiraceae-UCG-001, decreased ursodeoxycholic acids (UDCA) and hyodeoxycholic acids (HDCA), and increased fatty acids metabolites in feces.

CONCLUSION

In conclusion, we analyzed the changes of intestinal microbial composition and metabolites in diabetic mice after canagliflozin intervention and found that canagliflozin influenced intestinal fatty acid and bile acid (BA) metabolism. This study will provide reference for subsequent SGLT2i and intestinal related research.

Systemic metabolic depletion of gut microbiome undermines responsiveness to melanoma immunotherapy

Immunotherapy has proven to be a boon for patients battling metastatic melanoma, significantly improving their clinical condition and overall quality of life. A compelling link between the composition of the gut microbiome and the efficacy of immunotherapy has been established in both animal models and human patients. However, the precise biological mechanisms by which gut microbes influence treatment outcomes remain poorly understood. Using a robust dataset of 680 fecal metagenomes from melanoma patients, a detailed catalog of metagenome-assembled genomes (MAGs) was constructed to explore the compositional and functional properties of the gut microbiome. Our study uncovered significant findings that deepen the understanding of the intricate relationship between gut microbes and the efficacy of melanoma immunotherapy. In particular, we discovered the specific metagenomic profile of patients with favorable treatment outcomes, characterized by a prevalence of MAGs with increased overall metabolic potential and proficiency in polysaccharide utilization, along with those responsible for cobalamin and amino acid production. Furthermore, our investigation of the biosynthetic pathways of short-chain fatty acids, known for their immunomodulatory role, revealed a differential abundance of these pathways among the specific MAGs. Among others, the cobalamin-dependent Wood-Ljungdahl pathway of acetate synthesis was directly associated with responsiveness to melanoma immunotherapy.

The relationship between the gut microbiota and oxidative stress in the cognitive function of schizophrenia: A pilot study in China

Cognitive impairment is a core symptom of schizophrenia. The gut microbiota (GM) and oxidative stress may play important roles in the pathophysiological mechanisms of cognitive impairment. This study aimed to explore the relationship between GM and oxidative stress in the cognitive function of schizophrenia. GM obtained by 16S RNA sequencing and serum superoxide dismutase (SOD) levels from schizophrenia patients (N = 68) and healthy controls (HCs, N = 72) were analyzed. All psychiatric symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Cognitive function was assessed using the MATRICS Consensus Cognitive Battery (MCCB). Correlation analysis was used to explore the relationship between GM, SOD, and cognitive function. Machine learning models were used to identify potential biomarkers. Compared to HCs, the relative abundances of Collinsella, undefined Ruminococcus, Lactobacillus, Eubacterium, Mogibacterium, Desulfovibrio, Bulleidia, Succinivibrio, Corynebacterium, and Atopobium were higher in patients with schizophrenia, but Faecalibacterium, Anaerostipes, Turicibacter, and Ruminococcus were lower. In patients with schizophrenia, the positive factor, general factor, and total score of MCCB positively correlated with Lactobacillus, Collinsella, and Lactobacillus, respectively; SOD negatively correlated with Eubacterium, Collinsella, Lactobacillus, Corynebacterium, Bulleidia, Mogibacterium, and Succinivibrio, but positively correlated with Faecalibacterium, Ruminococcus, and MCCB verbal learning index scores; Faecalibacterium and Turicibacter were positively correlated with MCCB visual learning index scores and speed of processing index scores, respectively. Our findings revealed a correlation between SOD and GM and confirmed that cognitive dysfunction in patients with schizophrenia involves abnormal SOD levels and GM changes.

Advancements in enhancing resistant starch type 3 (RS3) content in starchy food and its impact on gut microbiota: A review

Resistant starch type 3 (RS3), often found in cooked starchy food, has various health benefits due to its indigestible properties and physiological functions such as promoting the abundance of gut beneficial microbial flora and inhibiting the growth of intestinal pathogenic bacteria. However, it is challenging to develop starchy food with high RS3 content. This review aims to provide a detailed overview of current advancements to enhance RS3 content in starchy food and its effects of RS3 on gut microbiota. These approaches include breeding high-amylose cereals through gene editing techniques, processing, enzyme treatments, storage, formation of RS3 nanoparticles, and the incorporation of bioactive compounds. The mechanisms, specific conditions, advantages, and disadvantages associated with each approach and the potential effects of RS3 prepared by different methods on gut microbiota are summarized. In conclusion, this review contains important information that aims to provide guidelines for developing an efficient RS3 preparation process and promote the consumption of RS3-enriched starchy foods to improve overall health outcomes.