Fatty acids produced by the gut microbiota dampen host inflammatory responses by modulating intestinal SUMOylation

The gut microbiota produces a wide variety of metabolites, which interact with intestinal cells and contribute to host physiology. These metabolites regulate intestinal cell activities by modulating either gene transcription or post-translational modifications of gut proteins. The effect of gut commensal bacteria on SUMOylation, an essential ubiquitin-like modification in intestinal physiology, remains however unknown. Here, we show that short chain fatty acids (SCFAs) and branched chain fatty acids (BCFAs) produced by the gut microbiota increase protein SUMOylation in different intestinal cell lines in a pH-dependent manner. We demonstrate that these metabolites induce an oxidative stress which inactivates intestinal deSUMOylases and promotes the hyperSUMOylation of chromatin-bound proteins. In order to determine the impact of these modifications on intestinal physiology, we focused on the NF-kappaB signaling pathway, a key player in inflammation known to be regulated by SUMOylation. We demonstrated that the hyperSUMOylation induced by SCFAs/BCFAs inhibits the activation of the NF-kappaB pathway in intestinal cells by blocking the degradation of the inhibitory factor IkappaBalpha in response to TNFalpha. This results in a decrease in pro-inflammatory cytokines expression, such as IL8 or CCL20, as well as a decrease in intestinal epithelial permeability in response to TNFalpha. Together, our results reveal that fatty acids produced by gut commensal bacteria regulate intestinal physiology by modulating SUMOylation and illustrate a new mechanism of dampening of host inflammatory responses by the gut microbiota.

Comparison of expression profiles between undifferentiated and differentiated porcine IPEC-J2 cells

Background The intestinal porcine enterocyte cell line (IPEC-J2) is a well-established model to study porcine intestinal physiology. IPEC-J2 cells undergo spontaneous differentiation during culture while changes in expression patterns of differentiated IPEC-J2 remain unclear. Therefore, this study was aimed to investigate the expression profiles of IPEC-J2 cells at the transcriptional level. Differentially expressed genes (DEGs), enriched pathways and potential key genes were identified. Alkaline phosphatase (AKP) and percentages of apoptotic cells were also measured. Results Overall, a total of 988 DEGs were identified, including 704 up-regulated and 284 down-regulated genes. GO analysis revealed that epithelial cell differentiation, apoptotic signaling pathway, regulation of cytokine production and immune system process, regulation of cell death and proliferation, cell junction complexes, and kinase binding were enriched significantly. Consistently, KEGG, REACTOME, and CORUM analysis indicated that cytokine responses modulation may be involved in IPEC-J2 differentiation. Moreover, AKP activity, a recognized marker of enterocyte differentiation, was significantly increased in IPEC-J2 after 14 days of culture. Meanwhile, annexin V-FITC/PI assay demonstrated a remarkable increase in apoptotic cells after 14 days of culture. Additionally, 10 hub genes were extracted, and STAT1, AKT3, and VEGFA were speculated to play roles in IPEC-J2 differentiation. Conclusions These findings may contribute to the molecular characterization of IPEC-J2, and may progress the understanding of cellular differentiation of swine intestinal epithelium.

Effect of different dietary fibre sources on the zootechnical performance, feeding behaviour and intestinal physiology of growing and finishing pigs

The aim of this study was to determine the effect of different sources of fibre in the diets of fattening pigs on performance, feeding behaviour and intestinal physiology. A total of 60 barrows and gilts (initial body weight 28.4 ± 0.4 kg) were allotted to four dietary treatments: control (CON), lignocellulose (LC), mycelium (MYC) and corn gluten feed (CGF). Diets were calculated to provide balanced available nutrient contents. Including MYC in the diet resulted in an increased average daily gain (P < 0.05) compared to CON and CGF, and improved gain to feed ratio (P < 0.05) compared to LC. Pigs in CON (P < 0.05) ate the fewest but largest meals, whereas treatment CGF (P < 0.05) showed the opposite effect, resulting in the same daily feeder occupation time. Regarding intestinal physiology, in ileum, no differences were observed between the contents of short chain fatty acids (SCFA), lactic acid and biogenic amines. In the colon, MYC showed an increased concentration of acetic acid (P < 0.05) as well as the total content of SCFA (P < 0.05), compared to LC and CGF. Distinct fermentation profiles of ammonia were recorded in ileal and colonic digesta, although contents remained below harmful concentrations. Morphometrical measurements showed differences between the fibre sources LC and MYC, as well as LC and the CON in all investigated gut sections. These results provide evidence that the inclusion of specific dietary fibre sources/contents can positively influence the gut morphology and performance of pigs. However, further studies are needed regarding the mode of action and physico-chemical characteristics of the different fibre sources as a precondition for their successful application in pig diets.

Dopamine Modulates Drosophila Gut Physiology, Providing New Insights for Future Gastrointestinal Pharmacotherapy

Dopamine has a variety of physiological roles in the gastrointestinal tract (GI) through binding to Drosophila dopamine D1-like receptors (DARs) and/or adrenergic receptors and has been confirmed as one of the enteric neurotransmitters. To gain new insights into what could be a potential future promise for GI pharmacology, we used Drosophila as a model organism to investigate the effects of dopamine on intestinal physiology and gut motility. GAL4/UAS system was utilized to knock down specific dopamine receptors using specialized GAL4 driver lines targeting neurons or enterocytes cells to identify which dopamine receptor controls stomach contractions. DARs (Dop1R1 and Dop1R2) were shown by immunohistochemistry to be strongly expressed in all smooth muscles in both larval and adult flies, which could explain the inhibitory effect of dopamine on GI motility. Adult males’ gut peristalsis was significantly inhibited by knocking down dopamine receptors Dop1R1, Dop1R2, and Dop2R, but female flies’ gut peristalsis was significantly repressed by knocking down only Dop1R1 and Dop1R2. Our findings also showed that dopamine drives PLC-β translocation from the cytoplasm to the plasma membrane in enterocytes for the first time. Overall, these data revealed the role of dopamine in modulating Drosophila gut physiology, offering us new insights for the future gastrointestinal pharmacotherapy of neurodegenerative diseases associated with dopamine deficiency.

High-fat diet–induced colonocyte dysfunction escalates microbiota-derived trimethylamine N-oxide

A Western-style, high-fat diet promotes cardiovascular disease, in part because it is rich in choline, which is converted to trimethylamine (TMA) by the gut microbiota. However, whether diet-induced changes in intestinal physiology can alter the metabolic capacity of the microbiota remains unknown. Using a mouse model of diet-induced obesity, we show that chronic exposure to a high-fat diet escalates Escherichia coli choline catabolism by altering intestinal epithelial physiology. A high-fat diet impaired the bioenergetics of mitochondria in the colonic epithelium to increase the luminal bioavailability of oxygen and nitrate, thereby intensifying respiration-dependent choline catabolism of E. coli. In turn, E. coli choline catabolism increased levels of circulating trimethlamine N-oxide, which is a potentially harmful metabolite generated by gut microbiota.

Identification and characterization of pathogenic E. coli -specific bacteriophages and polyvalent bacteriophages in piglet gut with increasing coliphage numbers after weaning

Post-weaning diarrhoea in pigs is mainly caused by pathogenic Escherichia coli and is a major source of revenue loss to the livestock industry. Bacteriophages dominate the gut virome and have the potential to regulate bacterial communities and thus influence the intestinal physiology. To determine the biological characterization of intestinal coliphages, we isolated and identified the faecal coliphages of healthy pre-weaned and post-weaned piglets from Nanjing and Chuzhou pig farms. First, ahead of coliphage isolation, 87 E. coli strains were isolated from healthy or diarrheal faecal samples from three pig farms, of which 8 were pathogenic strains including ETEC and EPEC. 87.3% of E. coli strains possessed drug resistance against three antibiotics. Using these 87 E. coli strains as indicator hosts, we isolated 45 coliphages and found a higher presence in the post-weaning stage than pre-weaning stage (24 vs 17 in Nanjing farm, 13 vs 4 in Chuzhou farm). Further more, each farm had a one most prevalent coliphage strain. Pathogenic E. coli -specific bacteriophages were commonly detected (9/10 samples in Nanjing farm, 7/10 in Chuzhou farm) in guts of sampled piglet and most had significant bacteriostatic effects ( P < 0.05) on pathogenic E. coli strains. Three polyvalent bacteriophages (N24, N30, and C5) were identified. The N30 and C5 strains showed a genetic identity of 89.67% with mild differences in infection characteristics. Our findings suggest that pathogenic E. coli -specific bacteriophages as well as polyvalent bacteriophages are commonly present in piglet gut and that weaning is an important event that affects coliphage numbers. IMPORTANCE Previous studies based on metagenomic sequencing reported that gut bacteriophages profoundly influence gut physiology but did not provide information regarding the host range and biological significance. Here, we screened coliphages from pre-weaned and post-weaned piglet gut against indicator hosts, which allowed us to identify the pathogenic E. coli -specific bacteriophages and polyvalent bacteriophages in pig farms and quantify their presence. Our approach complements sequencing methods and provides new insights into the biological characterizations of bacteriophage in the gut along with the ecological effects of intestinal bacteriophages.

The translational roadmap of the gut models, focusing on gut-on-chip

It is difficult to model in vitro the intestine when seeking to include crosstalk with the gut microbiota, immune and neuroendocrine systems. Here we present a roadmap of the current models to facilitate the choice in preclinical and translational research with a focus on gut-on-chip. These micro physiological systems (MPS) are microfluidic devices that recapitulate in vitro the physiology of the intestine. We reviewed the gut-on-chips that had been developed in academia and industries as single chip and that have three main purpose: replicate the intestinal physiology, the intestinal pathological features, and for pharmacological tests.

Effect of Kefir, Yacon (Smallanthus sonchifolius) and the Association Between Yacon and Kefir on Intestinal Physiology in Rats With Colon Cancer

Objectives To evaluate the effect of consumption of yacon flour, kefir and the association between them on colon cancer induced by 1,2-dimethylhydrazine (DMH) in male Wistar rats, SCFA production, fecal pH and intestinal permeability. Methods The study was conducted with 60 adult Wistar rats divided into 5 groups. For 5 weeks, groups T, Y, K and YK received 1,2-dimethylhydrazine (DMH) to induce colon cancer. After 5 weeks of DMH administration, animals in groups C and T received the standard diet, group Y received a diet with yacon flour with 5% FOS, group K received 1mL /day of kefir and the YK group received a diet with yacon and kefir, for 15 weeks. After euthanasia, intestinal lesions, intraluminal pH, short-chain fatty acids (SCFA) and intestinal permeability were analyzed. Results An increase in macroscopic lesions was observed in groups K (58%) and YK (42%) and a reduction of 5% in group Y, compared to group T. In addition, an increase in neoplastic changes was observed in all groups compared to group T: Y (33%), K (67%) and YK (78%). There was no significant difference in the concentrations of acetate and proprionate, pH, lactulose and mannitol between groups, and butyrate was not found in the samples. Conclusions The consumption of yacon flour, kefir and their association did not influence intestinal physiology and promoted the worsening of the development of colon carcinogenesis in rats. Funding Sources FAPES - Fundação de Amparo à Pesquisa e Inovação do Espírito Santo CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico