短链脂肪酸在疾病治疗中的研究进展

Study on the Hepatoprotective Effect Mechanism of Polysaccharides from Charred Angelica sinensis on the Layer Chickens Based on the Detection of the Intestinal Floras and Short-Chain Fatty Acids of Cecal Contents and Association Analysis

To analyze the intervention mechanism of polysaccharides from charred Angelica sinensis (CASP) on the liver injury caused by Ceftiofur sodium (CS) and lipopolysaccharide (LPS) from the perspective of the intestine. Ninety-four one-day-old laying chickens underwent free feeding and drinking water for three days. Then, fourteen laying chickens were randomly selected as the control group, and sixteen laying chickens were selected as the model group. Sixteen laying chickens in the rest were randomly selected as the intervention group of CASP. Chickens in the intervention group were given CASP by the oral administration (0.25 g/kg/d) for 10 days, the control and model groups were given the same amount of physiological saline. During the 8th and 10th days, laying chickens in the model and CASP intervention group were subcutaneously injected with CS at the neck. In contrast, those in the control group were subcutaneously injected with the same amount of normal saline simultaneously. Except for the control group, the layer chickens in the model and CASP intervention groups were injected with LPS after CS injection on the 10th day of the experiment. In contrast, those in the control group were injected with the same amount of normal saline at the same time. 48 h after the experiment, the liver samples of each group were collected, and the liver injury was analyzed by hematoxylin-eosin (HE) staining and transmission electron microscopy. And the cecum contents of six-layer chickens in each group were collected, and the intervention mechanism of CASP on the liver injury from the perspective of the intestine was analyzed by the 16S rDNA amplicon sequencing technology and the short-chain fatty acids (SCFAs) detection of cecal contents based on Gas Chromatography-Mass Spectrometry (GC-MS), and their association analysis was carried out. The results showed that the structure of chicken liver in the normal control group was normal, while that in the model group was damaged. The structure of chicken liver in the CASP intervention group was similar to the normal control group. The intestinal floras in the model group were maladjusted compared to the normal control group. After the intervention of CASP, the diversity, and richness of chicken intestinal floras changed significantly. It was speculated that the intervention mechanism of CASP on the chicken liver injury might be related to the abundance and proportion of Bacteroidetes and Firmicutes. Compared with the model group, the indexes of ace, chao1, observed species, and PD whole tree of chicken cecum floras in the intervention group of CASP were significantly increased (p < 0.05). The contents of acetic acid, butyric acid, and total SCFAs in the intervention group of CASP were significantly lower than those in the model group (p < 0.05), and the contents of propionic acid and valeric acid in the intervention group of CASP were significantly lower than those in the model group (p < 0.05) and normal control group (p < 0.05). The correlation analysis showed that the changes in the intestinal floras were correlated with the changes in SCFAs in the cecum. It is confirmed that the liver-protecting effect of CASP is indeed related to the changes in the intestinal floras and SCFAs content in the cecum, which provides a basis for screening liver-protecting alternative antibiotics products for poultry.

Progress in research of intestinal microbiota related short chain fatty acids

Short chain fatty acids (SCFAs) are the end products of the fermentation of difficult-to-digest carbohydrates in the small intestine by gut microbes. Dietary fiber, resistant starch, and oligosaccharides are the main substrates for SCFAs production, while undigested proteins or peptides may also be substrates for intestinal microbe SCFAs. Acetic acid, propionic acid, and butyric acid are the most abundant SCFAs in the intestinal tract, while the contents of formic acid, pentanoic acid, and hexanoic acid are significantly lower. As one of the main metabolites of intestinal flora, SCFAs play an important role in maintaining water and electrolyte balance, regulating intestinal flora balance, improving intestinal function, exerting anti-inflammatory and anti-tumor effects, and regulating gene expression. In this paper, we briefly introduce the generation, action mechanism, absorption, and metabolism of SCFAs, and summarize the related substrates producing SCFAs and the main effects of SCFAs on the intestinal tract, as well as the effects of SCFAs on various organs of the body, with an aim to provide theoretical guidance for clinical application of SCFAs in the intervention of various diseases.

Alterations in the Gut Microbiota of Tibetan Patients With Echinococcosis

There are two main types of echinococcosis, namely alveolar echinococcosis (AE) and cystic echinococcosis (CE). They are zoonotic parasitic diseases caused by the metacestodes of Echinococcus multilocularis and Echinococcus granulosus. In order to explore the gut microbiome composition of patients with echinococcosis, we analyzed fecal samples of seven patients with AE, six patients with CE, and 13 healthy individuals from the Qinghai-Tibetan Plateau, China. Using metagenomic next-generation sequencing, we identified fecal bacteria in the patients with AE and CE. The gut microbiota was analyzed by next-generation metagenomic sequencing (mNGS) to compare patients with either AE or CE against healthy individuals. We found there were some differences between them in abundant bacteria. Our results led to five findings: (1) Between patients with echinococcosis and healthy individuals, the differential bacteria were from four phyla: Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria. (2) Rothia mucilaginosa, Veillonella dispar, Veillonella atypica, Streptococcus parasanguinis, Streptococcus salivarius, and Alistipes finegoldii were abundant in the feces of patients with AE. (3) Bacteroides dorei, Parabacteroides distasonis, Escherichia sp_E4742, and Methanobrevibacter smithii were abundant in the feces of the patients with CE. (4) At the phylum and class level, compared to the AE group, the healthy group was characterized by higher numbers of Actinobacteria. (5) At the family level, Lachnospiraceae and Eubacteriaceae were more abundant in the feces of healthy individuals than in AE patients. The genera Coprococcus, Eubacterium, and Bilophia were more abundant in the healthy group, while the genus Rothia was more abundant in the AE group. The results of this study enrich our understanding of the gut microbiome composition of patients with AE and CE in the Qinghai-Tibetan Plateau.

The Diagnostic Potential of Gut Microbiota-Derived Short-Chain Fatty Acids in Preeclampsia

Preeclampsia (PE) is a complex pregnancy-related hypertensive disorder leading to multiorgan dysfunction. It has high maternal, fetal, and neonatal morbidity and mortality rates. The study of gut microbiota and its metabolites in PE deserves further exploration. Thirty-eight pregnant women with PE and 29 healthy pregnant women in the third trimester of their pregnancy were recruited in this study. We used a targeted metabolomics approach to evaluate the short-chain fatty acids (SCFAs) in serum samples. The correlation between SCFAs and clinical characteristics was also explored. The results of mass spectrometry (MS) showed significant differences at the metabolomics level of SCFAs between the PE and healthy control. The metabolic levels of acetate, propionate, isobutyrate, and valerate were significantly increased in the PE group than in the healthy control group. In contrast, caproic acid and butyrate levels were significantly reduced. The correlation analysis showed that urea, systolic, and diastolic blood pressure levels were positively correlated with four types of SCFAs (acetic acid, propionic acid, isobutyric acid, and valeric acid) which increased in the PE group. Furthermore, the neutrophil percentage and the fetal birth weight were negatively correlated with isobutyric acid and valeric acid. In addition, the receiver operating characteristic (ROC) analysis using a generalized linear model showed that multiple SCFAs would be potential diagnostic markers for PE, with high specificity, sensitivity, and area under the curve (AUC). Among them, isobutyric acid (sensitivity: 97.4%, specificity: 100%, AUC = 1.00), propionic acid (sensitivity: 86.8%, specificity: 93.3%, AUC = 0.954) and acetic acid (sensitivity: 86.8%, specificity: 83.3%, AUC = 0.891) depicted significantly higher diagnostic value and potential clinical applications. In summary, the results of this study indicate that SCFAs have the potential to become effective biomarkers for early screening of PE.

Role of gut-liver axis dysfunction in pathogenesis of non-alcoholic fatty liver disease: Implications for treatment strategies

Non-alcoholic fatty liver disease (NAFLD) is a chronic metabolic disease whose pathogenesis is not fully understood and involves multiple factors. Metabolic disorder caused by gut microbial imbalance is a key factor contributing to the development of NAFLD. Several studies show that gut barrier dysfunction will cause the occurrence of toxic metabolites in blood and bacterial translocation. The "dialogue" between the gut and the liver highlights the key role of the gut-liver axis in the process of NAFLD. This paper will summarize the relationship between the gut-liver axis and the pathogenesis of NAFLD, as well as its implications for the treatment of NAFLD.