Modulation of Short-Chain Fatty Acids as Potential Therapy Method for Type 2 Diabetes Mellitus

Edible traditional Chinese medicines improve type 2 diabetes by modulating gut microbiotal metabolites

Type 2 diabetes mellitus (T2DM) is a metabolic disorder with intricate pathogenic mechanisms. Despite the availability of various oral medications for controlling the condition, reports of poor glycemic control in type 2 diabetes persist, possibly involving unknown pathogenic mechanisms. In recent years, the gut microbiota have emerged as a highly promising target for T2DM treatment, with the metabolites produced by gut microbiota serving as crucial intermediaries connecting gut microbiota and strongly related to T2DM. Increasingly, traditional Chinese medicine is being considered to target the gut microbiota for T2DM treatment, and many of them are edible. In studies conducted on animal models, edible traditional Chinese medicine have been shown to primarily alter three significant gut microbiotal metabolites: short-chain fatty acids, bile acids, and branched-chain amino acids. These metabolites play crucial roles in alleviating T2DM by improving glucose metabolism and reducing inflammation. This review primarily summarizes twelve edible traditional Chinese medicines that improve T2DM by modulating the aforementioned three gut microbiotal metabolites, along with potential underlying molecular mechanisms, and also incorporation of edible traditional Chinese medicines into the diets of T2DM patients and combined use with probiotics for treating T2DM are discussed.

Lowering glycemic levels via gastrointestinal tract factors: the roles of dietary fiber, polyphenols, and their combination

Dietary fiber (DF) and polyphenols (DP) are typical blood sugar-lowering components, and both play distinct yet interconnected roles in exerting their blood sugar-lowering effects. We comprehensively summarized the single and combined effects of DF and DP on blood glucose homeostasis through regulating the relevant factors in the upper gastrointestinal tract (UGT) and lower gastrointestinal tract (LGT). In the UGT, DF slowed down glucose metabolism by enhancing digesta viscosity and hindering enzyme-substrate interaction. DP primarily targeted enzymes and substrates. When combined, DP enhanced the adsorption capacity of DF for glucose. DF weakened DP's inhibitory effect on enzymes. Both DF and DP disrupted glucose intestinal uptake via physical or genomic modulation, but the co-consumption of DF and DP demonstrated a lower inhibitory effect on glucose uptake than DP alone. In the LGT, DF and DP showed synergistic or antagonistic effects on gut microbiota. Remarkably, whole foods exhibited potent prebiotic effects due to their compound-rich matrix, potentially enhancing glucose homeostasis and expanding dietary options for glucose regulation research.

The Effect of Theaflavins on the Gut Microbiome and Metabolites in Diabetic Mice

With the development of diabetes, the gut microbiome falls into a state of dysbiosis, further affecting its progression. Theaflavins (TFs), a type of tea polyphenol derivative, show anti-diabetic properties, but their effect on the gut microbiome in diabetic mice is unclear. It is unknown whether the improvement of TFs on hyperglycemia and hyperlipidemia in diabetic mice is related to gut microbiota. Therefore, in this study, different concentrations of TFs were intragastrically administered to mice with diabetes induced by a high-fat-diet to investigate their effects on blood glucose, blood lipid, and the gut microbiome in diabetic mice, and the plausible mechanism underlying improvement in diabetes was explored from the perspective of the gut microbiome. The results showed that the TFs intervention significantly improved the hyperglycemia and hyperlipidemia of diabetic mice and affected the structure of the gut microbiome by promoting the growth of bacteria positively related to diabetes and inhibiting those negatively related to diabetes. The changes in short-chain fatty acids in mice with diabetes and functional prediction analysis suggested that TFs may affect carbohydrate metabolism and lipid metabolism by regulating the gut microbiome. These findings emphasize the ability of TFs to shape the diversity and structure of the gut microbiome in mice with diabetes induced by a high-fat diet combined with streptozotocin and have practical implications for the development of functional foods with TFs.

Short-chain fatty acid, butyrate prevents morphine-and paclitaxel-induced nociceptive hypersensitivity

Nociceptive hypersensitivity is a significant side effect with the chronic administration of opioids as well as chemotherapeutics. Both opioid-induced hypersensitivity (OIH) and chemotherapy-induced hypersensitivity (CIH) are characterized by an increased sensitivity to painful stimuli which can significantly reduce the quality of life for individuals on either drug(s). Here we demonstrate the nociceptive hypersensitivity associated with repeated administration of morphine (opioid) and paclitaxel (chemotherapeutic) treatment can be reversed by oral supplementation with the short-chain fatty acid (SCFA) sodium butyrate (NaBut). In two separate mouse behavioral models for nociceptive hypersensitivity, we found that thermal hyperalgesia (for OIH) and cold allodynia (for CIH) were prevented by treatment with oral butyrate (p.o, b.i.d). Electrophysiological recordings of small diameter dorsal root ganglia (DRG) neurons from morphine and paclitaxel treated mice showed an increase in neuronal hyperexcitability in both drug models which was likewise prevented by oral butyrate treatment. Using colonic conditioned media obtained from excised colon segments we found that gut mediators of morphine treated mice can induce hyperexcitability in naïve DRG neurons, but such enhanced excitability is not present when animals are co-treated with NaBut suggesting gut derived mediators modulate neuronal hyperexcitability. In-vitro NaBut treatment did not prevent morphine-induced excitability, suggesting an indirect role of butyrate in modulating neuronal hypersensitivity. These data taken together suggest that gut derived mediators affect opioid and chemotherapeutic-induced neuronal hypersensitivity that is prevented by the SCFA butyrate.

Oral administration of Bifidobacterium longum WHH2270 ameliorates type 2 diabetes in rats

Accumulating evidence suggests that specific probiotic strains exert hypoglycemic effects on type 2 diabetes mellitus (T2DM), and probiotic strains within Bifidobacterium exhibit potential beneficial effects on T2DM. In this study, α-glucosidase inhibitory activities of 14 Bifidobacterium strains were assessed in vitro. The hypoglycemic effects of Bifidobacterium longum WHH2270 with high α-glucosidase inhibitory activity (42.03%) were then investigated in a high-fat diet/streptozotocin-induced T2DM rat model. Oral administration of WHH2270 (4 × 109 CFU/kg/day) for 8 weeks significantly reversed the reduced body weight and ameliorated the levels of fasting blood glucose, serum triglyceride, serum total cholesterol, glucose tolerance, and insulin resistance in T2DM rats. Using 16S rRNA high-throughput sequencing of feces, WHH2270 was revealed to reshape the gut microbiome composition by increasing the abundances of Lactobacillus and Bifidobacterium and decreasing the abundances of UCG_005, Clostridium, and Faecalibacterium in T2DM rats. Besides, the fecal levels of short-chain fatty acids (SCFAs) including acetate, propionate, and butyrate were also elevated after WHH2270 administration. Moreover, the gene expressions of SCFA receptors FFAR2 and FFAR3 in the colon and pancreas of T2DM rats were restored by WHH2270 administration, accompanied by increased levels of serum acetate. In summary, these results provide evidence that WHH2270 has the potential to improve T2DM symptoms by alleviating hyperglycemia, which was associated with changes in the gut microbiome composition and SCFA production. PRACTICAL APPLICATION: Bifidobacterium longum WHH2270 with high α-glucosidase inhibitory activity may serve as a promising hypoglycemic agent for the treatment of T2DM.

Insight into role of short chain fatty acids in regulating intestinal mucosal barrier and alleviating inflammatory bowel disease

In recent years, the importance of intestinal microbiota and its metabolites in maintaining the human intestinal environment has been gradually revealed. Therefore, short chain fatty acids (SCFAs), as the metabolites produced by the intestinal microbiota, play a momentous part in regulating the balance between the function and morphology of the mucosal barrier, regulating the proliferation and differentiation of mucosal cells, protecting the integrity and permeability of the mucosal barrier, and maintainingthe stability of tight junctions. Inflammatory bowel disease (IBD) is a chronic, inflammatory condition of the gastrointestinal tract, associated with a disturbance of intestinal barrier function and dysregulation of the intestinal immune responses, the etiology and pathogenesis of which, however, are not yet fully uncovered. Animal models and human studies have corroborated the contribution of SCFAs in enhancing the barrier function through protective effects. This review will summarize the potential role of SCFAs in IBD with regard to regulating intestinal function, hoping to provide a new target for clinical treatment of IBD.

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.

Effects of Stocking Density on Fatty Acid Metabolism by Skeletal Muscle in Mice

Specific pathogen-free (SPF) grade laboratory animals are kept in specific cages for life. The limited space could affect the characterization of colonization and dynamic changes related to gut microorganisms, and affect adipokines, even further affecting the fat synthesis and muscle quality of animals. The objective of this study was to analyze the stocking density on the dynamic distribution of gut microbiota, fat synthesis and muscle quality of SPF grade Kunming mice. Three housing densities were accomplished by raising different mice per cage with the same floor size. Kunming mice were reared at low stocking density (LSD, three mice a group), medium stocking density (MSD, 5 mice a group), and high stocking density (HSD, 10 mice a group) for 12 weeks. The results demonstrated that the stocking density affected intestinal microbial flora composition. We found that compared with the MSD group, the abundance of Lactobacillus in the LSD group and the HSD group decreased, but the abundance of unclassified_Porphyromonadaceae increased. Moreover, fat synthesis and muscle quality were linked to the intestinal microbial flora and stocking density. Compared with the LSD group and the HSD group, the MSD group had a more balanced gut flora, higher fat synthesis and higher muscle quality. Overall, this study demonstrated that stocking density could affect gut microbiota composition, and reasonable stocking density could improve fat synthesis and muscle quality. Our study will provide theoretical support for the suitable stocking density of laboratory animals.

Arabinoxylans-Based Oral Insulin Delivery System Targeting the Colon: Simulation in a Human Intestinal Microbial Ecosystem and Evaluation in Diabetic Rats

Arabinoxylans (AX) microcapsules loaded with insulin were prepared by enzymatic gelation of AX, using a triaxial electrospray method. The microcapsules presented a spherical shape, with an average size of 250 µm. The behavior of AX microcapsules was evaluated using a simulator of the human intestinal microbial ecosystem. AX microcapsules were mainly (70%) degraded in the ascending colon. The fermentation was completed in the descending colon, increasing the production of acetic, propionic, and butyric acids. In the three regions of the colon, the fermentation of AX microcapsules significantly increased populations of Bifidobacterium and Lactobacillus and decreased the population of Enterobacteriaceae. In addition, the results found in this in vitro model showed that the AX microcapsules could resist the simulated conditions of the upper gastrointestinal system and be a carrier for insulin delivery to the colon. The pharmacological activity of insulin-loaded AX microcapsules was evaluated after oral delivery in diabetic rats. AX microcapsules lowered the serum glucose levels in diabetic rats by 75%, with insulin doses of 25 and 50 IU/kg. The hypoglycemic effect and the insulin levels remained for more than 48 h. Oral relative bioavailability was 13 and 8.7% for the 25 and 50 IU/kg doses, respectively. These results indicate that AX microcapsules are a promising microbiota-activated system for oral insulin delivery in the colon.

Potential Application of Living Microorganisms in the Detoxification of Heavy Metals

Heavy metal (HM) exposure remains a global occupational and environmental problem that creates a hazard to general health. Even low-level exposure to toxic metals contributes to the pathogenesis of various metabolic and immunological diseases, whereas, in this process, the gut microbiota serves as a major target and mediator of HM bioavailability and toxicity. Specifically, a picture is emerging from recent investigations identifying specific probiotic species to counteract the noxious effect of HM within the intestinal tract via a series of HM-resistant mechanisms. More encouragingly, aided by genetic engineering techniques, novel HM-bioremediation strategies using recombinant microorganisms have been fruitful and may provide access to promising biological medicines for HM poisoning. In this review, we summarized the pivotal mutualistic relationship between HM exposure and the gut microbiota, the probiotic-based protective strategies against HM-induced gut dysbiosis, with reference to recent advancements in developing engineered microorganisms for medically alleviating HM toxicity.

Treating the Onset of Diabetes Using Probiotics Along with Prebiotic from Pachyrhizus erosus in High-Fat Diet Fed Drosophila melanogaster

The increasing mortality due to hypertension and hypercholesterolemia is directly linked with type-2 diabetes. This shows the lethality of the disease. Reports suggest that the prebiotics along with probiotics help in lowering the effects of type-2 diabetes. Prebiotic like inulin is best known for its anti-diabetic effect. The current study utilizes jicama extract as prebiotic source of inulin along with the bacterial strains with probiotic properties (Lactiplantibacillus plantarum and Enterococcus faecium) for treating type-2 diabetes in high-fat diet-induced Drosophila melanogaster model. The high-fat diet-induced Drosophila showed deposition of lipid droplets and formation of micronuclei in the gut. The larva and adult treated with probiotics and synbiotic (probiotic + prebiotic- inulin) comparatively reduced the lipid deposition and micronuclei number in the gut. The increased amount of triglyceride in the whole body of the fatty larva and adult indicated the onset of diabetes. The overexpression of insulin-like genes (Dilp 2) and (Dilp 5) confirmed the insulin resistance, whereas the expression was reduced in the larva and adult supplemented with probiotics and synbiotic. The reactive oxygen species level was reduced with the supplementation of probiotics. The weight, larva size, crawling speed and climbing were also altered in high-fat diet-induced Drosophila melanogaster. The study confirmed the effects of probiotics and synbiotic in successfully lowering diabetes in Drosophila. The study also proved the anti-diabetic potential of the probiotics. Further, it was also confirmed that the probiotics work better in the presence of prebiotic.

[Influence of enteral feeding initiation time on intestinal flora and metabolites in very low birth weight infants: a prospective study]

OBJECTIVES

To study the influence of enteral feeding initiation time on intestinal flora and metabolites in very low birth weight (VLBW) infants.

METHODS

A total of 29 VLBW infants who were admitted to the Department of Neonatology, Children's Hospital of Chongqing Medical University, from June to December, 2020, were enrolled as subjects. According to the enteral feeding initiation time after birth, the infants were divided into two groups: <24 hours (n=15) and 24-72 hours (n=14). Fecal samples were collected at weeks 2 and 4 of hospitalization, and 16S rDNA high-throughput sequencing and gas chromatography-mass spectrometry were used to analyze the microflora and short-chain fatty acids (SCFAs) respectively in fecal samples.

RESULTS

The analysis of microflora showed that there was no significant difference between the two groups in Chao index (reflecting the abundance of microflora) and Shannon index (reflecting the diversity of microflora) at weeks 2 and 4 after birth (P>0.05). The analysis of flora composition showed that there was no significant difference in the main microflora at the phylum and genus levels between the two groups at weeks 2 and 4 after birth (P>0.05). The comparison of SCFAs between the two groups showed that the <24 hours group had a significantly higher level of propionic acid than the 24-72 hours group at week 4 (P<0.05), while there was no significant difference in the total amount of SCFAs and the content of the other SCFAs between the two groups (P>0.05).

CONCLUSIONS

Early enteral feeding has no influence on the diversity and abundance of intestinal flora in VLBW infants, but enteral feeding within 24 hours can increase the level of propionic acid, a metabolite of intestinal flora.

Daily Inclusion of Resistant Starch-Containing Potatoes in a Dietary Guidelines for Americans Dietary Pattern Does Not Adversely Affect Cardiometabolic Risk or Intestinal Permeability in Adults with Metabolic Syndrome: A Randomized Controlled Trial

Poor diet quality influences cardiometabolic risk. Although potatoes are suggested to adversely affect cardiometabolic health, controlled trials that can establish causality are limited. Consistent with potatoes being rich in micronutrients and resistant starch, we hypothesized that their inclusion in a Dietary Guidelines for Americans (DGA)-based dietary pattern would improve cardiometabolic and gut health in metabolic syndrome (MetS) persons. In a randomized cross-over trial, MetS persons (n = 27; 32.5 ± 1.3 year) consumed a DGA-based diet for 2 weeks containing potatoes (DGA + POTATO; 17.5 g/day resistant starch) or bagels (DGA + BAGEL; 0 g/day resistant starch) prior to completing oral glucose and gut permeability tests. Blood pressure, fasting glucose and insulin, and insulin resistance decreased (p < 0.05) from baseline regardless of treatment without any change in body mass. Oral glucose-induced changes in brachial artery flow-mediated dilation, nitric oxide homeostasis, and lipid peroxidation did not differ between treatment arms. Serum endotoxin AUC0−120 min and urinary lactulose/mannitol, but not urinary sucralose/erythritol, were lower in DGA + POTATO. Fecal microbiome showed limited between-treatment differences, but the proportion of acetate was higher in DGA + POTATO. Thus, short-term consumption of a DGA-based diet decreases cardiometabolic risk, and the incorporation of resistant starch-containing potatoes into a healthy diet reduces small intestinal permeability and postprandial endotoxemia.

Effects and Mechanisms of Probiotics, Prebiotics, Synbiotics, and Postbiotics on Metabolic Diseases Targeting Gut Microbiota: A Narrative Review

Metabolic diseases are serious threats to public health and related to gut microbiota. Probiotics, prebiotics, synbiotics, and postbiotics (PPSP) are powerful regulators of gut microbiota, thus possessing prospects for preventing metabolic diseases. Therefore, the effects and mechanisms of PPSP on metabolic diseases targeting gut microbiota are worth discussing and clarifying. Generally, PPSP benefit metabolic diseases management, especially obesity and type 2 diabetes mellitus. The underlying gut microbial-related mechanisms are mainly the modulation of gut microbiota composition, regulation of gut microbial metabolites, and improvement of intestinal barrier function. Moreover, clinical trials showed the benefits of PPSP on patients with metabolic diseases, while the clinical strategies for gestational diabetes mellitus, optimal formula of synbiotics and health benefits of postbiotics need further study. This review fully summarizes the relationship between probiotics, prebiotics, synbiotics, postbiotics, and metabolic diseases, presents promising results and the one in dispute, and especially attention is paid to illustrates potential mechanisms and clinical effects, which could contribute to the next research and development of PPSP.

Activation of the gut microbiota-kynurenine-liver axis contributes to the development of nonalcoholic hepatic steatosis in nondiabetic adults

The contribution of gut-liver signaling to the development of non-alcoholic hepatic steatosis (NHS) in non-diabetic adults remains unclear. We therefore performed comprehensive 16S ribosomal RNA sequencing and fecal metabolomics analyses in 32 controls and 59 non-diabetic adults with NHS and performed fecal microbiota transplantation into germ-free mice using controls and NHS patients as donors. Compared to controls, the abundance of the genera Collinsella and Acinetobacter were higher, while that of Lachnospira was lower, in NHS subjects. Fecal metabolomics analysis showed decreased L-tryptophan levels and increased abundance of the tryptophan metabolite kynurenine in individuals with NHS. Correlation analysis showed that kynurenine levels positively associated with the abundance of Collinsella and Acinetobacter. ROC analysis demonstrated that the combination of tryptophan and kynurenine could discriminate NHS patients from controls with good statistical power [P < 0.05; AUC = 0.833 (95% CI, 0.747 to 0.918)]. Supporting a key role of dysbiotic gut microbiota in NHS development, incipient hepatic steatosis and increased kynurenine levels were observed in GF mice colonized with samples from NHS patients. These results indicate that enhanced kynurenine production resulting from altered gut microbiota composition contributes to NHS in nondiabetic adults and suggest the relevance of tryptophan metabolites as diagnostic biomarkers.