Dataset Information

Exposure to High Aerial Ammonia Causes Hindgut Dysbiotic Microbiota and Alterations of Microbiota-Derived Metabolites in Growing Pigs.

ABSTRACT: Ammonia, an atmospheric pollutant in the air, jeopardizes immune function, and perturbs metabolism, especially lipid metabolism, in human and animals. The roles of intestinal microbiota and its metabolites in maintaining or regulating immune function and metabolism are irreplaceable. Therefore, this study aimed to investigate how aerial ammonia exposure influences hindgut microbiota and its metabolites in a pig model. Twelve growing pigs were treated with or without aerial ammonia (35 mg/m³) for 25 days, and then microbial diversity and microbiota-derived metabolites were measured. The results demonstrated a decreasing trend in leptin (p = 0.0898) and reduced high-density lipoprotein cholesterol (HDL-C, p = 0.0006) in serum after ammonia exposure. Besides, an upward trend in hyocholic acid (HCA), lithocholic acid (LCA), hyodeoxycholic acid (HDCA) (p < 0.1); a downward trend in tauro-deoxycholic acid (TDCA, p < 0.1); and a reduced tauro-HDCA (THDCA, p < 0.05) level were found in the serum bile acid (BA) profiles after ammonia exposure. Ammonia exposure notably raised microbial alpha-diversity with higher Sobs, Shannon, or ACE index in the cecum or colon and the Chao index in the cecum (p < 0.05) and clearly exhibited a distinct microbial cluster in hindgut indicated by principal coordinate analysis (p < 0.01), indicating that ammonia exposure induced alterations of microbial community structure and composition in the hindgut. Further analysis displayed that ammonia exposure increased the number of potentially harmful bacteria, such as Negativibacillus, Alloprevotella, or Lachnospira, and decreased the number of beneficial bacteria, such as Akkermansia or Clostridium_sensu_stricto_1, in the hindgut (FDR < 0.05). Analysis of microbiota-derived metabolites in the hindgut showed that ammonia exposure increased acetate and decreased isobutyrate or isovalerate in the cecum or colon, respectively (p < 0.05). Unlike the alteration of serum BA profiles, cecal BA data showed that high ammonia exposure had a downward trend in cholic acid (CA), HCA, and LCA (p < 0.1); a downward trend in deoxycholic acid (DCA) and HDCA (p < 0.05); and an upward trend in glycol-chenodeoxycholic acid (GCDCA, p < 0.05). Mantel test and correlation analysis revealed associations between microbiota-derived metabolites and ammonia exposure-responsive cecal bacteria. Collectively, the findings illustrated that high ammonia exposure induced the dysbiotic microbiota in the hindgut, thereby affecting the production of microbiota-derived short-chain fatty acids and BAs, which play a pivotal role in the modulation of host systematic metabolism.

SUBMITTER: Tang S

PROVIDER: S-EPMC8231926 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Aerial ammonia exposure leads to tissue damage and metabolic dysfunction. However, it is unclear how different organs are coordinated to defend against aerial ammonia exposure. Twenty-four pigs were randomly divided into 4 groups, exposed to 0, 10, 25 or 35 mg/m3 ammonia respectively for 25 d. After above 25 mg/m3 ammonia exposure, decreased aspartate (P = 0.016), glutamate (P = 0.030) and increased ornithine (P = 0.002) were found in the ammonia-removing liver, and after high ammonia (35 mg/m3) exposure, glutamine synthetase (GS) expression was increased (P = 0.012). An increased glutamate (P = 0.004) and decreased glutaminase (GLS) expression (P = 0.083) were observed in the lungs after high ammonia exposure. There was also an increasing trend of glutamine in the kidneys after high ammonia exposure (P = 0.066). For branched-chain amino acid (BCAA) catabolism, high ammonia exposure increased BCAA content in both the lungs and muscle (P < 0.05), whereas below 25 mg/m3 ammonia exposure increased BCAA only in the lungs (P < 0.05). The expression of BCAA transaminase (BCAT1/2) and dehydrogenase complex (BCKDHA/B and DBT) were inhibited to a varying degree in the liver, lungs and muscle after above 25 mg/m3 ammonia exposure, especially high ammonia exposure. The expression of BCKDH complex and glutamate-glutamine metabolism-related genes were highly expressed in the liver, followed by the lungs and muscle (P < 0.01), whereas the BCAT2 expression was highest in the lungs (P = 0.002). Altogether, low ammonia exposure sufficed to evoke the urea cycle to detoxify ammonia in the liver. The process of ammonia removal in the liver and potential ability of the lungs to detoxify ammonia were enhanced with increasing ammonia. Furthermore, high ammonia exposure impaired the BCAA catabolism and decreased the transcripts of the BCAA catabolism-related enzymes, resulting in high BCAA content in extrahepatic tissues. Therefore, with aerial ammonia increasing, an increased urea cycle and glutamine synthesis were ammonia defensive strategies, and high ammonia exposure impaired the BCAA catabolism.

Project description:Exposure to gaseous ammonia, even at low levels, can be harmful to pigs and human health. However, less is known about the effects of sustained exposure to gaseous ammonia on nasal microbiota colonization in growing pigs. A total of 120 Duroc×Landrace×Yorkshire pigs were housed in 24 separate chambers and continuously exposed to gaseous ammonia at 0,5, 10, 15, 20, and 25 ppm (four groups per exposure level) for 4 weeks. Then, we used high-throughput sequencing to perform 16S rRNA gene analysis in nasal swabs samples from 72 pigs (n = 12). The results of the nasal microbiota analysis showed that an increase in ammonia concentration, especially at 20 and 25 ppm, decreased the alpha diversity and relative abundance of nasal microbiota. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Chloroflexi were the most abundant phyla. In addition, the relative abundances of 24 microbial genera significantly changed as the ammonia level increased. Four microbial genera (Pseudomonas, Lactobacillus, Prevotella, and Bacteroides) were significantly decreased at 25 ppm, while only two genera (Moraxella and Streptococcus) were increased at 25 ppm. PICRUSt analyses showed that the relative abundances of the nasal microbiota involved in cell motility, signal transduction, the nervous system, environmental adaptation, and energy and carbohydrate metabolism were significantly decreased, while genes involved in the immune system, endocrine system, circulatory system, immune system diseases and metabolism of vitamins, lipid, and amino acids were increased with increased ammonia levels. The results of in vivo tests showed that an increase in ammonia levels, especially an ammonia level of 25 ppm, caused respiratory tract injury and increase the number of Moraxella and Streptococcus species, while simultaneously decreasing respiratory immunity and growth performance, consistent with the increased presence of harmful bacteria identified by nasal microbiota analysis. Herein, this study also indicted that the threshold concentration of ammonia in pig farming is 20 ppm.

Dataset Information

Exposure to High Aerial Ammonia Causes Hindgut Dysbiotic Microbiota and Alterations of Microbiota-Derived Metabolites in Growing Pigs.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets