Role and mechanism of intestinal flora metabolites in obesity regulation / 中国组织工程研究

BACKGROUND:Gut microbiota is closely related to host energy balance and metabolism.The metabolites of intestinal flora can regulate the occurrence and development of obesity and can be a new target for the prevention and treatment of obesity. OBJECTIVE:To summarize the interaction between the intestinal flora and obesity,as well as the specific mechanism underlying regulation of obesity by metabolites of intestinal flora,thereby providing a new reference and basis for the prevention and treatment of obesity. METHODS:"Intestinal microbiota,intestinal bacteria,intestinal microbiota metabolites,short-chain fatty acids,bile acids,ipopolysaccharide,trimethylamine N-oxide,medium-chain fatty acids,tryptophan derivatives,obesity"were used as search terms in Chinese and English.Literature related to obesity from 1990 to 2022 was retrieved in PubMed and CNKI databases.According to inclusion and exclusion criteria,88 articles were finally selected. RESULTS AND CONCLUSION:Intestinal flora is closely related to the occurrence and development of obesity.For example,changes in the Firmicutes to Bacteroidetes ratio can be used as a biomarker for the diagnosis of obesity,and the occurrence of obesity can be delayed by the colonization of probiotics such as Bifidobacterium breve,Lactobacillus and Akkermansia.Intestinal flora is mainly mediated by the metabolites of intestinal flora to participate in the regulation of obesity.For example,short-chain fatty acid can regulate adipogenesis by regulating signaling pathways such as G protein-coupled receptors 41,43 and peroxisome proliferator-activated receptor γ,thus delaying the occurrence and development of obesity.Bile acids can increase insulin sensitivity and body energy expenditure by promoting the activation of G protein-coupled receptor 5 and farnesol X receptor.In addition,lipopolysaccharide,trimethylamine oxide,medium-chain fatty acids and tryptophan derivatives are also widely involved in the occurrence and development of obesity through various signaling pathways.Further studies have found that metabolites of the same bacterial community exert heterogeneous effects in the specific process of regulating obesity via different signaling pathways.For example,under the influence of high-fat diet,acetic acids can activate the parasympathetic nervous system,leading to hyperphagia and liver insulin resistance and thus accelerating the physiological course of obesity.

Targeted Metabonomics Combined with 16SrRNA Gene Sequencing to Analyze the Effect of Rehmanniae Radix on Intestinal Flora in Rats with Kidney Yin Deficiency Syndrome Before and After Processing / 中药新药与临床药理

Objective To investigate the effects of Rehmanniae Radix before and after processing on the intestinal flora of rats with kidney yin deficiency syndrome.Methods SD rats were randomly divided into blank group,model group,probiotic group(0.35 g·kg-1),high-/medium-/low-dose groups of Rehmanniae Radix Praeparata(3.5,1.75,0.875 g·kg-1),and high-/medium-/low-dose groups of Rehmanniae Radix(3.5,1.75,0.875 g·kg-1),with 9 rats in each group.Except for the blank group,rats in each group were injected intramuscularly with Dexamethasone Sodium Phosphate Injection(0.35 mg·kg-1)once a day for 21 days.The drug was administered by gavage once a day on the seventh day of modelling for 14 days.The adrenal histopathological changes were observed by using HE staining;the levels of serum cyclic adenosine monophosphate(cAMP),cyclic guanosine monophosphate(cGMP),corticotropin-releasing hormone(CRH),adrenocorticotropic hormone(ACTH),and corticosterone(CORT)were detected by ELISA;and the levels of short-chain fatty acids in the feces and changes in the diversity of intestinal flora were detected by a targeted metabolomic approach in conjunction with 16SrRNA sequencing in the rats in each group.Results(1)Compared with the blank group,the body mass of rats in the model group was significantly decreased on days 7,14 and 21(P＜0.05,P＜0.01);serum levels of cAMP,CRH,ACTH,CORT and the cAMP/cGMP ratio were all significantly increased(P＜0.01),and the cGMP content was significantly decreased(P＜0.01);and the adrenal cortex was thinned,with the boundaries of various layers of the cortex unclear.Compared with the model group,the body mass of rats in the Rehmanniae Radix Praeparata administration group on day 21 were all significantly increased(P＜0.05,P＜0.01),and the serum content of cAMP,CRH,ACTH,CORT and the cAMP/cGMP ratio were all significantly decreased(P＜0.05,P＜0.01),and the content of cGMP was significantly increased(P＜0.05,P＜0.01)in the rats;body mass of rats in the Rehmanniae Radix administration group did not change significantly(P＞0.05),CRH and CORT contents in serum of rats in the high-dose group of Rehmanniae Radix were significantly reduced(P＜0.01),and ACTH contents in serum of rats in the medium-dose group of Rehmanniae Radix were significantly reduced(P＜0.05);the adrenal cortex of rats in all the administration groups were improved,in particular,the thickening of the adrenal cortex layers was obvious in the Rehmanniae Radix Praeparata group,and the improvement effect was superior to that in the Rehmanniae Radix group.(2)Compared with the blank group,the difference of Coverage index was not statistically significant(P＞0.05),and the coverage of each group was good;the abundance index(Sobs,Ace,Chao)and diversity index(Shannon)of the model group were significantly increased(P＜0.01),and the Simpson index was significantly decreased(P＜0.01).Compared with the model group,Sobs index was significantly decreased in the medium-and high-dose groups of Rehmanniae Radix Praeparata(P＜0.05),Chao index was significantly decreased in the administered groups of Rehmanniae Radix Praeparata and high-dose group of Rehmanniae Radix(P＜0.05,P＜0.01),and Simpson index was significantly increased in the high-dose group of Rehmanniae Radix Praeparata(P＜0.05).The changes of Rehmanniae Radix on the richness and diversity of intestinal microbial community in kidney yin-deficient rats were small,while Rehmanniae Radix Praeparata could better maintain the stability of the richness and diversity of intestinal microbial community in kidney yin-deficient rats.(3)Compared with the blank group,the abundance of phylum firmicutes in the feces of the model group was significantly decreased,while the abundance of bacteroides and actinomycetes was significantly increased.The abundance of Lactobacillus was significantly decreased(P＜0.01),while the abundance of norank_f__Muribaculaceae and Bifidobacterium was significantly increased(P＜0.01).Compared with the model group,the trend of recovery of bacterial abundance in the probiotic group and the high-dose group of Rehmanniae Radix Praeparata was more similar to that of the blank group,which showed that it had the best regulating effect on the ratio of bacterial flora;the abundance of lactobacillus in all administered groups was increased,with that of the probiotic group was significantly increased(P＜0.01);the abundance of norank__f__Muribaculaceae and Bifidobacterium were all decreased,among which the probiotic group and the medium-and high-dose groups of Rehmanniae Radix Praeparata were significantly decreased(P＜0.01),and the effect was significantly superior to that of Rehmanniae Radix.The COG functions of the samples in each group were mainly focused on amino acid transport and metabolism,carbohydrate transport and metabolism,translation,ribosomal structure and biogenesis,replication,recombination and repair,but the abundance information of each function was different between groups,which may be due to the differences caused by dysbiosis of intestinal flora.(4)Compared with the blank group,the levels of acetic acid,butyric acid and propionic acid in the faeces of rats in the model group were significantly decreased(P＜0.05,P＜0.01),and the level of isobutyric acid was significantly increased(P＜0.01).Compared with the model group,the levels of acetic acid,butyric acid and propionic acid in the faeces of rats in the probiotic group and the low-,medium-and high-dose groups of Rehmanniae Radix Praeparata were significantly increased(P＜0.05,P＜0.01)and the levels of isobutyric acid were significantly decreased(P＜0.05,P＜0.01);although the above indexes in the Rehmanniae Radix group were improved,the difference was not statistically significant(P＞0.05).Conclusion The enhanced therapeutic effect of Rehmanniae Radix after processing on rats with kidney yin deficiency syndrome may be related to its adjusting effect on intestinal flora.

Short chain fatty acid: a messenger of gut-organ axis for disease regulation / 药学学报

Gut microbiota is a complex and dynamic system, and is essential for the health of the body. As the "second genome" of the body, it can establish communication with the important organs by regulating intestinal nerves, gastrointestinal hormones, intestinal barrier, immunity and metabolism, thus affecting host′s physiological functions. Short chain fatty acid (SCFA), known as one important metabolite of intestinal microbiota, is regarded as a significant messenger of the gut-organ communication, due to its extensive regulation in the body′s immunity, metabolism, endocrine and signal transduction. In this review, we summarize the interaction between gut-liver/brain/kidney/lung axis and diseases, and focus on the role and mechanism of SCFA in the gut-organ communication, hoping to provide new ideas for the treatment of the related diseases.

Modulating effects of Astragalus polysaccharide on immune disorders via gut microbiota and the TLR4/NF-κB pathway in rats with syndrome of dampness stagnancy due to spleen deficiency / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

The syndrome of dampness stagnancy due to spleen deficiency (DSSD) is relatively common globally. Although the pathogenesis of DSSD remains unclear, evidence has suggested that the gut microbiota might play a significant role. Radix Astragali, used as both medicine and food, exerts the effects of tonifying spleen and qi. Astragalus polysaccharide (APS) comprises a macromolecule substance extracted from the dried root of Radix Astragali, which has many pharmacological functions. However, whether APS mitigates the immune disorders underlying the DSSD syndrome via regulating gut microbiota and the relevant mechanism remains unknown. Here, we used DSSD rats induced by high-fat and low-protein (HFLP) diet plus exhaustive swimming, and found that APS of moderate molecular weight increased the body weight gain and immune organ indexes, decreased the levels of interleukin-1β (IL-1β), IL-6, and endotoxin, and suppressed the Toll-like receptor 4/nuclear factor-‍κB (TLR4/NF-‍κB) pathway. Moreover, a total of 27 critical genera were significantly enriched according to the linear discriminant analysis effect size (LEfSe). APS increased the diversity of the gut microbiota and changed its composition, such as reducing the relative abundance of Pseudoflavonifractor and Paraprevotella, and increasing that of Parasutterella, Parabacteroides, Clostridium XIVb, Oscillibacter, Butyricicoccus, and Dorea. APS also elevated the contents of short-chain fatty acids (SCFAs). Furthermore, the correlation analysis indicated that 12 critical bacteria were related to the body weight gain and immune organ indexes. In general, our study demonstrated that APS ameliorated the immune disorders in DSSD rats via modulating their gut microbiota, especially for some bacteria involving immune and inflammatory response and SCFA production, as well as the TLR4/NF-κB pathway. This study provides an insight into the function of APS as a unique potential prebiotic through exerting systemic activities in treating DSSD.

Electro-acupuncture promotes gut motility and alleviates functional constipation by regulating gut microbiota and increasing butyric acid generation in mice / 中西医结合学报

OBJECTIVE@#Abnormalities in the gut microbiota and intestinal short-chain fatty acid (SCFA) levels are implicated in the pathogenesis of functional constipation (FC). Electro-acupuncture (EA) has been shown to improve constipation-related symptoms and rebalance the gut microbiota. However, it is currently unknown whether the gut microbiota is a key mechanistic target for EA or how EA promotes gut motility by regulating the gut microbiota and SCFAs. Therefore, we assessed the effects of EA in FC mice and pseudo-germfree (PGF) mice to address these questions.@*METHODS@#Forty female Kunming mice were randomly separated into a normal control group (n = 8), an FC group (n = 8), an FC + EA group (n = 8), a PGF group (n = 8) and a PGF + EA group (n = 8). The FC group and FC + EA group were treated with diphenoxylate to establish the FC model; the PGF group and PGF + EA group were given an antibiotic cocktail to initiate the PGF model. After maintaining the model for 14 d, mice in the FC + EA and PGF + EA groups received EA stimulation at the ST25 and ST37 acupoints, once a day, 5 times per week, for 2 weeks. Fecal parameters and intestinal transit rate were calculated to assess the efficacy of EA on constipation and gastrointestinal motility. Colonic contents were used to quantify gut microbial diversity using 16S rRNA sequencing, and measure SCFA concentrations using gas chromatography-mass spectrometry.@*RESULTS@#EA significantly shortened the first black stool defecation time (P < 0.05) and increased the intestinal transit rate (P < 0.01), and fecal pellet number (P < 0.05), wet weight (P < 0.05) and water content (P < 0.01) over 8 h, compared with the FC group, showing that EA promoted gut motility and alleviated constipation. However, EA treatment did not reverse slow-transit colonic motility in PGF mice (P > 0.05), demonstrating that the gut microbiota may play a mechanistic role in the EA treatment of constipation. In addition, EA treatment restored the Firmicutes to Bacteroidetes ratio and significantly increased butyric acid generation in FC mice (P < 0.05), most likely due to the upregulation of Staphylococcaceae microorganisms (P < 0.01).@*CONCLUSION@#EA-mediated resolution of constipation occurs through rebalancing the gut microbiota and promoting butyric acid generation. Please cite this article as: Xu MM, Guo Y, Chen Y, Zhang W, Wang L, Li Y. Electro-acupuncture promotes gut motility and alleviates functional constipation by regulating gut microbiota and increasing butyric acid generation in mice. J Integr Med. 2023; Epub ahead of print.

Macrophage polarization induced by short-chain fatty acid attenuates acute lung injury in sepsis / 中华危重病急救医学

Objective:To explore the effect of short-chain fatty acid (SCFA) on acute lung injury (ALI) in sepsis via macrophage polarization.Methods:① Clinical trial: 30 sepsis patients admitted to the intensive care unit (ICU) of General Hospital of Ningxia Medical University from January to December in 2022 and 10 non-sepsis patients in the same period were enrolled, stool samples were collected on the first day of admission, and SCFA butyric acid level in the two groups were studied by targeted metabolomics. ② Animal experiment: male C57BL/6J mice were selected and randomly divided into sham operation group (Sham group), sepsis caused by cecal ligation and perforation (CLP group) and SCFA intervention group (SCFA group, sodium butyrate 25 mg/kg was given by gavage 1 hour after CLP), with 6 animals in each group. Twenty-four hours after molding, the state of mice was evaluated by mouse sepsis score (MSS), the degree of pulmonary edema was evaluated by calculating the wet/dry ratio (W/D), and the pathological changes of lung tissue were observed by hematoxylin-eosin (HE) staining, and lung injury score was performed. The serum levels of tumor necrosis factor-α (TNF-α), interleukins (IL-1β, IL-6, IL-10), nuclear factor-κB (NF-κB), and transforming growth factor-β (TGF-β) were detected by enzyme-linked immunosorbent assay (ELISA). Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to measure the mRNA expressions of inflammatory factors TNF-α, IL-1β, IL-6 and antioxidant factor nuclear factor E2-related factor 2 (Nrf2) in lung tissue. The expressions of macrophage polarization markers arginin-1 (ARG-1), CD206, inducible nitric oxide synthase (iNOS) and IL-1β in lung tissue were detected by immunohistochemistry.Results:① Compared with non-sepsis patients, SCFA-butyric acid level was significantly reduced in patients with sepsis (μg/g: 34.56±6.61 vs. 1 150.67±381.90, P < 0.01). ② Compared with the Sham group, MSS, lung W/D ratio, lung injury score, the levels of serum inflammatory factors TNF-α, TGF-β, NF-κB, IL-10, IL-6, IL-1β, the mRNA expressions of lung tissue inflammatory factors and antioxidant factor Nrf2, M1 macrophage polarization markers ARG-1, CD206 and M2 macrophage polarization markers iNOS and IL-1β were significantly increased in the CLP group. Compared with the CLP group, MSS, lung W/D ratio, lung injury score, the levels of serum inflammatory factors TNF-α, TGF-β, NF-κB, IL-10, IL-6, IL-1β, the mRNA expressions of lung tissue inflammatory factors and antioxidant factors Nrf2, and M1 macrophage polarization markers ARG-1 and CD206 were significantly reduced [MSS: 14.50±3.16 vs. 20.00±1.55, lung W/D ratio: 4.60±0.18 vs. 5.51±0.59, lung injury score: 47.56±2.36 vs. 88.30±6.04, serum TNF-α (ng/L): 27.99±0.58 vs. 69.55±18.53, serum TGF-β (μg/L): 9.82±2.16 vs. 18.73±1.83, serum NF-κB (μg/L): 1.23±0.09 vs. 1.95±0.28, serum IL-10 (ng/L): 78.39±2.29 vs. 140.22±19.82, serum IL-6 (ng/L): 300.64±77.60 vs. 1 442.52±494.14, serum IL-1β (ng/L): 33.13±0.99 vs. 38.39±1.31, lung IL-1β mRNA expression (IL-1β/β-actin): 1.01±0.01 vs. 2.24±0.62, lung IL-6 mRNA expression (IL-6/β-actin): 0.63±0.09 vs. 1.46±0.31, lung TNF-α mRNA expression (TNF-α/β-actin): 0.81±0.33 vs. 2.57±0.64, lung Nrf2 mRNA expression (Nrf2/β-actin): 1.59±0.25 vs. 2.96±0.89, ARG-1 positive area: (36.27±2.89)% vs. (49.75±5.03)%, CD206 positive area: (20.02±3.26)% vs. (44.24±3.61)%, all P < 0.05]. However, there was no significant difference in M2 macrophage polarization markers iNOS and IL-1β expression [iNOS positive area: (18.32±2.23)% vs. (21.77±3.57)%, IL-1β positive area: (40.42±4.78)% vs. (42.14±4.22)%, both P > 0.05]. Conclusion:SCFA may alleviate ALI in sepsis by reducing M1 polarization of pulmonary macrophages.

Research progress of intestinal microorganisms and pathogenesis of diabetes mellitus / 预防医学

Abstract@#As the largest human microecosystem, intestinal microorganisms participate in human material and energy metabolisms and pose a significant impact on human health. Diabetes mellitus is likely to cause imbalance of abundance and component alterations in intestinal microorganisms, and reduce the diversity and balance, leading to intestinal microflora dysregulation. It has been shown that intestinal microflora dysregulation may promote diabetes development and progression through the reduction of intestinal microbial metabolites, inflammatory reaction and insulin resistance. This review summarizes the involvement of intestinal microorganisms in the pathogenesis of diabetes through metabolites including short-chain fatty acid, bile acid and lipopolysaccharide, and describes the current status of intestinal microorganisms-mediated treatments for diabetes, so as to provide the theoretical basis for the researches on diabetes and intestinal microorganisms.

Influence of enteral feeding initiation time on intestinal flora and metabolites in very low birth weight infants: a prospective study / 中国当代儿科杂志

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.

Research progress on the role of short-chain fatty acids in the treatment of ulcerative colitis / 中华临床营养杂志

Short-chain fatty acids (SCFAs), as the main energy source for colonic epithelial cells, are becoming one of the important nutritional agents in the treatment of E1 (proctitis) and E2 (left-sided) subtypes of ulcerative colitis. To date, the therapeutic effects of topical SCFAs as primary or adjuvant induction therapy have been studied. However, the specific mechanism of action for SCFAs in the pathogenesis and progression of ulcerative colitis needs further investigation. High-quality prospective studies are required to verify current opinions on the selection of SCFA mixtures and the choice of topical or systemic routes of administration. In addition, SCFA is considered as a promising agent to prevent the occurrence and progression of ulcerative colitis-related colorectal cancer. Therefore, the optimal timing to integrate SCFAs into the treatment of ulcerative colitis represents another future research direction.

Gynostemma pentaphyllum saponins alleviate non-alcoholic fatty liver disease in rats by regulating intestinal flora and short-chain fatty acid metabolism / 中国中药杂志

This study aimed to explore the effects of Gynostemma pentaphyllum saponins(GPs) on non-alcoholic fatty liver disease(NAFLD) induced by high-fat diet in rats and reveal the underlying mechanism. The NAFLD model rats were prepared with high-fat diet. Forty male Sprague Dawley(SD) rats were randomly assigned into the control group, model group, and low-, moderate-, and high-dose GPs(50, 100, and 150 mg·kg~(-1), respectively) groups. After intragastric administration for 8 continuous weeks, we determined the body weight, liver weight, the levels of total cholesterol(TC), triglyceride(TG), low-density lipoprotein cholesterol(LDL-c), high-density lipoprotein cholesterol(HDL-c), alanine aminotransferase(ALT), and aspartate aminotransferase(AST) in serum, and the levels of TC, TG, malondialdehyde(MDA), superoxide dismutase(SOD), catalase(CAT), and interleukin 6(IL-6) in the liver. Furthermore, we observed the pathological changes of liver tissue by oil red O staining and hematoxylin-eosin(HE) staining, sequenced the 16 S rRNA of the intestinal flora in rat feces, and determined the content of short-chain fatty acids in rat feces. The results showed that GPs inhibited the excessive weight gain of high-fat diet-induced NAFLD in rats, reduced the liver weight, lowered the TC, TG, LDL-c, AST, and ALT levels in serum(P<0.05), and rose the HDL-c level in serum(P<0.01). GPs relieved the liver damage caused by high-fat diet, mainly manifested by the lowered levels of TC, TG, MDA, and IL-6 in the liver(P<0.01) and elevated levels of CAT and SOD in the liver. Furthermore, GPs reversed the intestinal flora disorder caused by high-fat diet, restored the diversity of intestinal flora, increased the relative abundance of Bacteroides, and reduced the relative abundance of Firmicutes and the ratio of Firmicutes to Bacteroides. Moreover, GPs promoted the proliferation of beneficial bacteria such as Akkermansia, Bacteroides, and Parabacteroides, and inhibited the growth of harmful bacteria such as Desulfovibrio, Escherichia-Shigella, and Helicobacter. GPs increased the content of short-chain fatty acids(acetic acid, propionic acid, and butyric acid)(P<0.01). These findings indicate that GPs can alleviate the high-fat diet-induced NAFLD in rats via regulating the intestinal flora and short-chain fatty acid metabolism.

Effects of compound fermented milk on improving constipation in mice and underlying mechanism / 中华微生物学和免疫学杂志

Objective:To investigate the effects of compound fermented milk on intestinal microbiota, short chain fatty acid (SCFA), intestinal motility and mucosal barrier in mice with constipation.Methods:Twenty-seven C57BL/6JNifdc mice were randomly divided into three groups: control group, model group and intervention group. The model group and the intervention group were given loperamide intragastrically for two weeks. Starting from the second week, the intervention group was treated with compound fermented milk for 7 d. The control group was given normal saline. Food intake, water intake, weight change, fecal moisture content, time of first-time black stool and small intestine propulsion rate were detected. Expression of serotonin C receptor (5-HTR2C), zona occludins-1 (ZO-1) and mucin-2 (MUC-2) at mRNA level in colon was analyzed. Western blot was used to measure the expression of Raf/ERK/MAPK-related proteins. SCFA level in intestinal tract was detected by gas chromatography. Intestinal microbiota diversity was analyzed by high-throughput sequencing.Results:Compared with the control group, the first black stool excretion time was significantly prolonged in the model group ( P<0.01). Moreover, fecal moisture content, small intestine propulsion rate and the expression of 5-HTR2C and ZO-1 at mRNA level in colon were significantly decreased ( P<0.01). Compared with the model group, the first black stool excretion time was significantly shortened ( P<0.05); fecal moisture content, small intestine propelling rate ( P<0.05), the expression of colon 5-HTR2C and ZO-1 at mRNA level ( P<0.05), phosphorylation of Raf/ERK/MAPK pathway in the colon, intestinal SCFA-producing bacteria and intestinal SCFA content were increased in the intervention group. Conclusions:Compound fermented milk had a therapeutic effect on constipation in a mouse model by increasing the abundance of SCFA-producing bacteria and SCFA content, enhancing the phosphorylation of the Raf/ERK/MAPK pathway to up-regulate the expression of 5-HTR2C at mRNA level in the colon, and increasing the expression of ZO-1 at mRNA level in the colon. Intestinal peristalsis and intestinal mucosal barrier function were enhanced, thus improving the symptom of constipation.

Diagnosis and treatment strategy of intestinal flora imbalance after liver transplantation / 器官移植

Multiple short-term and long-term complications might occur after liver transplantation. In the early stage after liver transplantation, the incidence of multidrug-resistant bacteria is likely to cause different types of infection, one of which is intestinal flora imbalance. In the recent decade, a series of studies have demonstrated that intestinal flora plays an important role in maintaining intestinal homeostasis. Intestinal flora may interact with other organs via multiple patterns. Among which, gut-liver axis is one of the most critical channels for regulating microenvironment of the host. Changes in the quantity and composition of intestinal flora could lead to intestinal flora imbalance. In both local and systemic systems, extensive interaction exists between intestinal flora and immune system. In this article, the risk factors of intestinal flora imbalance after liver transplantation, influence of intestinal flora imbalance on liver transplant recipients and relevant treatment strategies were reviewed.

Exercise, Gut Microbial Metabolite: Short Chain Fatty Acid andRegulation of Skeletal Muscle Metabolism / 中国生物化学与分子生物学报

Gut microbiota, which is influenced by genetics, environment, diet, age and exercise, is a highly dynamic and individualized complex ecosystem and has a wide range of response effects with many tissues and organs through its metabolites. Short chain fatty acids (SCFA) are mainly produced by bacteria in cecum and colon by fermentation with dietary fiber as substrate, which is absorbed into the superior and inferior mesenteric vein, and then converges into the portal vein to the liver. Part of SCFA is used as the substrate of gluconeogenesis and lipid biosynthesis by liver, and the remaining SCFA enters the peripheral circulation through hepatic vein in the form of free fatty acids. It is found that exercise can improve the abundance of gut microbiota producing SCFA and the expression of genes involved in the regulation of SCFA production, and then increase the content of SCFA in the lumen. Glucagon likepeptide-1 (GLP-1) is synthesized and secreted by colon endocrine cells stimulated by SCFA. GLP-1 can promote islet B cells to synthesize and secrete insulin, which regulates skeletal muscle glucose uptake and glycogen synthesis. In addition, SCFA enhances the insulin sensitivity of skeletal muscle by increasing histone acetylation level on chromatin in proximity of the insulin receptor substrate 1 (Irs1) transcriptional start site. At the same time, SCFA can promote fatty acid uptake, lipid catabolism andmitochondrial biogenesis of skeletal muscle by activating AMP-activated protein kinase (AMPK), and then inhibit lipid anabolism. This paper reviewed the latest research progress in three aspects: summary of the gut microbial metabolites (SCFA), the effect of exercise on the gut microbiota producing SCFA, and the possible mechanism of exercise mediated SCFA on skeletal muscle metabolism. It may provide theoretical basis for the research on the new mechanism in the exercise adaptation of skeletal muscle.

Effects of short-chain fatty acids on inflammatory responses in THP-1 cells and COPD mice / 西安交通大学学报(医学版)

【Objective】 To explore the effects of anti-inflammatory of short-chain fatty acids in human peripheral blood mononuclear cells （THP-1） and chronic obstructive pulmonary （COPD） mice. 【Methods】 We adopted the methods of qRT-PCR， ELISA， Western blotting， HE staining and Sirius staining to detect the changes of inflammatory factors in THP-1 cells and COPD with or without short-chain fatty acids. 【Results】 The ELISA and qRT-PCR experiments showed that the serum inflammatory factors， including interleukin-6 （IL-6）， interleukin-1β （IL-1β） and tumor necrosis factor-α （TNF-α）， were higher in clinical COPD patients than in healthy people. And the THP-1 cells expressed these inflammatory factors highly after LPS stimulation. Among three short-chain fatty acids treated， butyrate could reduce the levels of inflammatory factors better than acetate and propionate. After COPD mice were treated with butyrate in the drinking water， the mRNA expressions of inflammatory factors IL-6， IL-1β and TNF-α in the lung tissue decreased， and the concentrations of IL-6 and IL-1β in plasma decreased. The protein detection results showed that the phosphorylation expression of NF-κB decreased， and butyrate might inhibit the expressions of inflammatory factors by inhibiting the NF-κB signaling pathway. 【Conclusion】 The SCFA butyrate can inhibit LPS-induced inflammatory response of THP-1 cells and have an inhibitory effect on inflammation in COPD mice.

Dengzhan Shengmai inhibits nonalcoholic fatty liver disease via regulating intestinal microenvironment / 药学学报

The aim of this study was to investigate the efficacy and mechanism of Dengzhan Shengmai (DZSM) against nonalcoholic fatty liver diseases (NAFLD). The animal experiment program was reviewed and approved by the Ethics Committee of Institute of Materia Medica, Chinese Academy of Medical Sciences. The NAFLD model of Syrian golden hamsters was established by high fat diets. After 6 weeks of DZSM treatment, the serum lipid, hepatic lipid accumulation, liver function and inflammatory response were determined. The regulations of gut microbiota and short-chain fatty acids were detected by 16S rRNA gene sequencing and gas chromatography-mass spectrometry method, respectively. The gut barrier function was evaluated by enzyme linked immunosorbent assay (ELISA), reverse transcription-quantitative polymerase chain reaction (RT-qPCR), Western blot and histopathological methods and further verified in HepG2 cells. The results showed that the efficacy of DZSM against NAFLD was remarkably reduced after removal of the gut microbiota. The study of mechanism showed that DZSM significantly regulated the composition of gut microbiota, promoted the production and absorption of intestinal short-chain fatty acids, then leading to the reduction of hepatic lipid accumulation. Moreover, after DZSM treatment, the decreased lipopolysaccharide (LPS) level by improving the intestinal barrier function significantly inhibited the hepatic inflammation through down-regulating Toll like receptor 4 (TLR4)-nuclear factor kappa B (NFKB) signaling pathway. These results indicate that DZSM inhibits NAFLD via regulating intestinal microenvironment.

Effect of the course of treatment with broad-spectrum antibiotics on intestinal flora and short-chain fatty acids in feces of very low birth weight infants: a prospective study / 中国当代儿科杂志

OBJECTIVES@#To study the effect of the course of treatment with broad-spectrum antibiotics on intestinal flora and short-chain fatty acids (SCFAs) in feces of very low birth weight (VLBW) infants.@*METHODS@#A total of 29 VLBW infants who were admitted to the Neonatal Diagnosis and Treatment Center of Children's Hospital Affiliated to Chongqing Medical University from June to December 2020 were enrolled as subjects for this prospective study. According to the course of treatment with broad-spectrum antibiotics, they were divided into two groups: ≤7 days (@*RESULTS@#There was a significant reduction in Chao index of the intestinal flora in the ≤7 days group and the >7 days group from week 2 to week 4 (@*CONCLUSIONS@#The course of treatment with broad-spectrum antibiotics can affect the abundance, colonization, and evolution of intestinal flora and the content of their metabolites SCFAs in VLBW infants. The indication and treatment course for broad-spectrum antibiotics should be strictly controlled in clinical practice.

Regulatory effect of total phenolic acid from the stems and leaves of Salvia miltiorrhiza Bge. on intestinal microflora and short-chain fatty acids in type 2 diabetic nephropathy mice / 药学学报

To study the regulating effect of total phenolic acids from the stems and leaves of Salvia miltiorrhiza Bge. on the intestinal flora and short-chain fatty acids in spontaneous type 2 diabetic nephropathy mice, db/db mice were taken as the research object, and were treated with the total phenolic acid of Salvia miltiorrhiza Bge. Animal welfare and experimental procedures followed the regulations of the Animal Ethics Committee of Nanjing University of Chinese Medicine Drug Safety Evaluation Research Center. Fresh feces and cecal contents of mice were collected for analysis of intestinal flora composition and differential flora. Gas chromatography was used to detect short-chain fatty acids in fresh feces and cecal content. Then the correlation analysis of the two results was made. Compared with the normal group, the most significant decreased differential flora in the model group were g_Rikenellaceae_ RC9_gut_group and g_Bacteroidales_S24-7_group, while the most significant increased were g_unclassified_f__ Coriobacteriaceae and g_unclassified_p__Firmicutes. Compared with the blank group, the contents of isovaleric acid and valeric acid in fresh feces and the contents of 6 short-chain fatty acids in the cecal contents of the model group were significantly reduced (P < 0.01). After drug intervention, the intestinal flora disorder and the reduction of short-chain fatty acids were improved to varying degrees, and the effect of the total phenolic acids from the stems and leaves of Salvia miltiorrhiza Bge. was slightly better than that from the roots in regulating some flora and short-chain fatty acids. The results of correlation analysis showed that g_Rikenellaceae_RC9_gut_group was moderately positively correlated with acetic acid and isobutyric acid in the cecal contents (r > 0.4). It is suggested that the total phenolic acid from the stems and leaves of Salvia miltiorrhiza Bge. can improve the intestinal flora disorder of mice with type 2 diabetic nephropathy, and can regulate the content of short-chain fatty acids in the intestine via adjusting the content of some short-chain fatty acid-producing bacteria, thereby helping to restore normal.

Determination of medium- and short-chain fatty acids in feces by UHPLC-QTOF-MS/MS with pre-column derivatization / 药学学报

A pre-column derivatization and ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS/MS) method was developed for qualitative and quantitative determination of medium- and short-chain fatty acids in mice feces, and was further applied to evaluate variations in the feces of mice before and after antibiotic treatment. This animal experiment had been approved by Animal Experimental Ethics Committee of Jiangsu Province Academy of Traditional Chinese Medicine. By optimizing the derivatization conditions and UHPLC-QTOF-MS/MS parameters a new UHPLC-QTOF-MS/MS method with 3-nitrophenylhydrazine as the derivatization reagent was developed for simultaneous determination of 16 medium- and short-chain fatty acids. Validation studies showed that the linearity of the calibration curves was good (R2>0.99), the RSD of intra-day and inter-day precision was less than 10%, the repeatability RSD was less than 6%, the recovery rate was between 80% - 120% at three spiked levels, and the stability RSD was less than 7% within 36 h. The types and amounts of the detected medium- and short-chain fatty acids in feces significantly changed after the mice were treated with antibiotics. The content of formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and lactic acid decreased, whereas that of heptanoic acid and succinic acid increased significantly. All these results suggest that the newly established method is accurate and reliable, and can be used for determination of medium- and short-chain fatty acids in feces.

Short-chain Fatty Acids Inhibit Staphylococcal Lipoprotein-induced Nitric Oxide Production in Murine Macrophages

Staphylococcus aureus, a Gram-positive pathogen, can cause severe inflammation in humans, leading to various life-threatening diseases. The lipoprotein is a major virulence factor in S. aureus-induced infectious diseases and is responsible for excessive inflammatory mediators such as nitric oxide (NO). Short-chain fatty acids (SCFAs) including butyrate, propionate, and acetate are microbial metabolites in the gut that are known to have anti-inflammatory effects in the host. In this study, we investigated the effects of SCFAs on S. aureus lipoprotein (Sa.LPP)-induced NO production in mouse macrophages. Butyrate and propionate, but not acetate, inhibited Sa.LPP-induced production of NO in RAW 264.7 cells and bone marrow-derived macrophages. Butyrate and propionate inhibited Sa.LPP-induced expression of inducible NO synthase (iNOS). However, acetate did not show such effects under the same conditions. Furthermore, butyrate and propionate, but not acetate, inhibited Sa.LPP-induced activation of NF-κB, expression of IFN-β, and phosphorylation of STAT1, which are essential for inducing transcription of iNOS in macrophages. In addition, butyrate and propionate induced histone acetylation at lysine residues in the presence of Sa.LPP in RAW 264.7 cells. Moreover, Sa.LPP-induced NO production was decreased by histone deacetylase (HDAC) inhibitors. Collectively, these results suggest that butyrate and propionate ameliorate the inflammatory responses caused by S. aureus through the inhibition of NF-κB, IFN-β/STAT1, and HDAC, resulting in attenuated NO production in macrophages.

Effects of Hericium erinaceus Polysaccharide on the Content of Short-chain Fatty Acids in the Intestine of Ulcerative Colitis Model Rats / 中国药房

OBJECTIVE： To investigate the effects of Hericium erinaceus polysaccharide on the content of short-chain fatty acids （SCFAs） in the intestine of ulcerative colitis model rats. METHODS： A total of 40 SD rats were randomly divided into blank group， model group and H. erinaceus polysaccharide low-dose and high-dose groups （0.5， 1.0 g/kg）， with 10 rats in each group. Except for blank group， other groups were given acetic acid enema to induce ulcerative colitis model. The next day after modeling， H. erinaceus polysaccharide groups were given relevant medicine solution intragastrically； blank group and model group were given relevant volume of water intragastrically， for 10 consecutive days. Colon tissue was collected， and pathological changes of colon tissue were observed by HE staining. The pathological changes of colon in rats were observed with naked eyes and scored so as to evaluate the therapeutic efficacy. The contents of 6 kinds of SCFAs （acetic acid，propionic acid，butyric acid，isobutyric acid，pentanoic acid and isovaleric acid） in intestine of rats were determined by GC-MS. RESULTS： Compared with blank group， inflammatory lesions of colonic mucosal epithelium in model group rats were obvious； colonic mucosal ulcer score increased significantly （P＜0.01）； the contents of 5 kinds of SCFAs and the total amount of SCFAs in colon except for propionic acid were decreased significantly （P＜0.01）. Compared with model group， the degree of colonic histopathological damage in H. erinaceus polysaccharide groups was significantly reduced； colonic mucosal ulcer scores were significantly reduced （P＜0.05 or P＜0.01）； the contents of 5 kinds of SCFAs and the total amount of SCFAs in colon except for propionic acid were increased significantly （P＜0.05 or P＜0.01）. CONCLUSIONS： H. erinaceus polysaccharide can effectively improve the pathological condition of ulcerative colitis model rats； its regulation of intestinal SCFAs （especially acetic acid and butyric acid） may be an important mechanism of its anti-ulcerative colitis.