Redox-related gaseous mediators in the gastrointestinal tract

Let food be your medicine - dietary fiber

Dietary fiber (DF) cannot be digested and absorbed by the digestive tract, nor can it provide the energy needed to be burned for metabolic activities. Therefore, from the 1950s to the 1980s, DF received little attention in nutrition studies. With in-depth research and developments in global nutrition, people have gradually paid attention to the fact that DF occupies an essential position in the structure of nutrition, and it can ensure the healthy development of human beings. As early as 390 B.C., the ancient Greek physician Hippocrates proposed, "Let your food be your medicine, and your medicine be your food". This concept has been more systematically validated in modern scientific research, with numerous epidemiological studies showing that the dietary intake of DF-rich foods such as whole grains, root vegetables, legumes, and fruits has the potential to regulate the balance of the gut microbiota and thereby prevent diseases. However, the crosstalk between different types of DF and the gut microbiota is quite complex, and the effects on the organism vary. In this paper, we discuss research on DF and the gut microbiota and related diseases, aiming to understand the relationship between all three better and provide a reference basis for the risk reduction of related diseases.

Dress me an outfit: advanced probiotics hybrid systems for intelligent IBD therapy

Inflammation bowel disease (IBD) has emerged as a public health challenge worldwide; with high incidence and rapid prevalence, it has troubled billions of people and further induced multitudinous systemic complications. Recent decade has witnessed the vigorous application of food-borne probiotics for IBD therapy; however, the complicated and changeable environments of digestive tract have forced probiotics to face multiple in vivo pressures, consequently causing unsatisfied prophylactic or therapeutic efficacy attributed to off-targeted arrival, damaged viability, insufficient colonization efficiency, etc. Fortunately, arisen hybrid technology has provided versatile breakthroughs for the targeted transplantation of probiotics. By ingeniously modifying probiotics to form probiotics hybrid systems (PHS), the biological behaviors of probiotics in vivo could be mediated, the interactions between probiotics with intestinal components can be facilitated, and diverse advanced probiotic-based therapies for IBD challenge can be developed, which attribute to the intelligent response to microenvironment of PHS, and intelligent design of PHS for multiple functions combination. In this review, various PHS were categorized and their intestinal behaviors were elucidated systematically, their therapeutic effects and intrinsic mechanism were further analyzed. Besides, shortages of present PHS and the corresponding solutions have been discussed, based on which the future perspectives of this field have also been proposed. The undeniable fact is that PHS show an incomparable future to bring the next generation of advanced food science.

Dynamics and metabolic effects of intestinal gases in healthy humans

Many living beings use exogenous and/or endogenous gases to attain evolutionary benefits. We make a comprehensive assessment of one of the major gaseous reservoirs in the human body, i.e., the bowel, providing extensive data that may serve as reference for future studies. We assess the intestinal gases in healthy humans, including their volume, composition, source and local distribution in proximal as well as distal gut. We analyse each one of the most abundant intestinal gases including nitrogen, oxygen, nitric oxide, carbon dioxide, methane, hydrogen, hydrogen sulfide, sulfur dioxide and cyanide. For every gas, we describe diffusive patterns, active trans-barrier transport dynamics, chemical properties, intra-/extra-intestinal metabolic effects mediated by intracellular, extracellular, paracrine and distant actions. Further, we highlight the local and systemic roles of gasotransmitters, i.e., signalling gaseous molecules that can freely diffuse through the intestinal cellular membranes. Yet, we provide testable hypotheses concerning the still unknown effects of some intestinal gases on the myenteric and submucosal neurons.

In vitro and in vivo fermentation models to study the function of dietary fiber in pig nutrition

The importance of dietary fiber (DF) in animal diets is increasing with the advancement of nutritional research. DF is fermented by gut microbiota to produce metabolites, which are important in improving intestinal health. This review is a systematic review of DF in pig nutrition using in vitro and in vivo models. The fermentation characteristics of DF and the metabolic mechanisms of its metabolites were summarized in an in vitro model, and it was pointed out that SCFAs and gases are the important metabolites connecting DF, gut microbiota, and intestinal health, and they play a key role in intestinal health. At the same time, some information about host-microbe interactions could have been improved through traditional animal in vivo models, and the most direct feedback on nutrients was generated, confirming the beneficial effects of DF on sow reproductive performance, piglet intestinal health, and growing pork quality. Finally, the advantages and disadvantages of different fermentation models were compared. In future studies, it is necessary to flexibly combine in vivo and in vitro fermentation models to profoundly investigate the mechanism of DF on the organism in order to promote the development of precision nutrition tools and to provide a scientific basis for the in-depth and rational utilization of DF in animal husbandry. KEY POINTS: • The fermentation characteristics of dietary fiber in vitro models were reviewed. • Metabolic pathways of metabolites and their roles in the intestine were reviewed. • The role of dietary fiber in pigs at different stages was reviewed.

Gastroprotective effect methanol extract of Caesalpinia coriaria pods against indomethacin- and ethanol-induced gastric lesions in Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Caesalpinia coriaria (Jacq.) Willd is widely used as a traditional medinal plant in Mexico for protective and healing purposes and the treatment of gastrointestinal diseases.

AIM OF THE STUDY

To investigate the gastroprotective effect of extract of Caesalpinia coriaria pods against ethanol-induced and indomethacin-induced gastric lesion models, its anti-inflammatory and antioxidative activities, and its main compounds through LC-MS analysis.

MATERIALS AND METHODS

Male Wistar rats were orally administered a methanol extract obtained from the pods of C. coriaria at doses of 10, 30, 100, and 300 mg/kg prior to inducing gastric lesions with ethanol or indomethacin. Gastric mucosal lesions were evaluated by macroscopic and histopathological alterations. Determination of prostaglandin E₂ (PGE₂), alpha tumor necrosis factor (TNF-α), leukotriene B₄ (LTB₄), nitrites/nitrates, superoxide dismutase (SOD), and H₂S gastric levels were investigated. Its main compounds of the active extract through LC-MS analysis.

RESULTS

Phenolic compounds were identified as major components of methanol extract. LC-MS analysis identified 15 constituents, and the significant compounds were gallic acid, 3-O-galloylquinic acid, digalloylglucose, tetragalloylglucose, valoneic acid dilactone, pentagalloylglucose, digalloylshikimic acid, and ellagic acid. Pretreatment with the extract at doses of 100 and 300 mg/kg significantly reduced gastric ulcer lesions in both models. Compared with the reference drugs (omeprazole or ranitidine, respectively), no significant difference was found (p < 0.05). The extract's gastroprotective effect was accompanied by significant decreases in leukocyte recruitment, and gastric levels of TNF-α and LTB₄ by two to fourfold (p < 0.05). Also, gastric levels of PGE₂ gastric levels were maintained and the antioxidant enzyme activities of SOD and nitrate/nitrite in the gastric tissue were improved (p < 0.05). The LC-MS analysis indicated the presence of hydrolyzable tannins (mainly gallic acid derivatives).

CONCLUSION

The results suggest that the gastroprotective effect of the methanol extract of C. coriaria pods occurs through anti-inflammatory, antioxidant, and NO modulation properties, and gallic acid derivatives may be the main possible compounds responsible for its actions.

A protocol for the cultivation and monitoring of ileal gut microbiota surrogates

AIMS

This research aimed to develop and validate a cultivation and monitoring protocol that is suitable for a surrogate microbial community that accounts for the gut microbiota of the ileum of the small intestine.

METHODS AND RESULTS

Five bacterial species have been selected as representatives of the ileal gut microbiota and a general anaerobic medium (MS-BHI, as minimally supplemented BHI) has been constructed and validated against BCCM/LGM recommended and commercial media. Moreover, appropriate selective/differential media have been investigated for monitoring each ileal gut microbiota surrogate. Results showed that MS-BHI was highly efficient in displaying individual and collective behavior of the ileal gut microbiota species, when compared with other types of media. Likewise, the selective/differential media managed to identify and describe the behavior of their targeted species.

CONCLUSIONS

MS-BHI renders a highly efficient, inexpensive and easy-to-prepare cultivation and enumeration alternative for the surrogate ileal microbiota species. Additionally, the selective/differential media can identify and quantify the bacteria of the surrogate ileal microbial community.

SIGNIFICANCE AND IMPACT OF STUDY

The selected gut microbiota species can represent an in vitro ileal community, forming the basis for future studies on small intestinal microbiota. MS-BHI and the proposed monitoring protocol can be used as a standard for gut microbiota studies that utilize conventional microbiological techniques.

Gut Microbial Metabolites and Blood Pressure Regulation: Focus on SCFAs and TMAO

Shifts in the gut microbiome play a key role in blood pressure regulation, and changes in the production of gut microbial metabolites are likely to be a key mechanism. Known gut microbial metabolites include short-chain fatty acids, which can signal via G-protein-coupled receptors, and trimethylamine-N oxide. In this review, we provide an overview of gut microbial metabolites documented thus far to play a role in blood pressure regulation.

Nature's marvels endowed in gaseous molecules I: Carbon monoxide and its physiological and therapeutic roles

Nature has endowed gaseous molecules such as O2, CO2, CO, NO, H2S, and N2 with critical and diverse roles in sustaining life, from supplying energy needed to power life and building blocks for life's physical structure to mediating and coordinating cellular functions. In this article, we give a brief introduction of the complex functions of the various gaseous molecules in life and then focus on carbon monoxide as a specific example of an endogenously produced signaling molecule to highlight the importance of this class of molecules. The past twenty years have seen much progress in understanding CO's mechanism(s) of action and pharmacological effects as well as in developing delivery methods for easy administration. One remarkable trait of CO is its pleiotropic effects that have few parallels, except perhaps its sister gaseous signaling molecules such as nitric oxide and hydrogen sulfide. This review will delve into the sophistication of CO-mediated signaling as well as its validated pharmacological functions and possible therapeutic applications.

Helicobacter pylori infection modulates endogenous hydrogen sulfide production in gastric cancer AGS cells

BACKGROUND

Persistent Helicobacter pylori infection induces gastric mucosal atrophy, which is a precancerous condition. Hydrogen sulfide (H₂ S), a gaseous biological transmitter, has been implicated in both the physiological functions of the gastrointestinal tract and its diseases. To understand gastric epithelial cell response against H pylori infection, we investigated the metabolic changes of gastric cancer cells co-cultured with H pylori and observed the modulation of endogenous H₂ S production.

MATERIALS AND METHODS

Gastric cancer AGS cells were co-cultured with an H pylori standard strain possessing bacterial virulence factor CagA (ATCC 43504) and a strain without CagA (ATCC 51932). Three hours after inoculation, the cells were subjected to metabolomics analysis using gas chromatography-tandem mass spectrometry (GC-MS/MS). Orthogonal projections to latent structures discriminant analysis (OPLS-DA) and pathway analysis were performed. In addition, intracellular H₂ S levels were measured by using HSip-1 fluorescent probe.

RESULTS

Results of OPLS-DA showed a significant difference between the metabolism of untreated control cells and cells inoculated with the H pylori strains ATCC 51932 or ATCC 43504, mainly due to 45 metabolites. Pathway analysis with the selected metabolites indicated that methionine metabolism, which is related to H₂ S production, was the most frequently altered pathway. H pylori-inoculated cells produced more endogenous H₂ S than control cells. Moreover, ATCC 43504-inoculated cells produced less H₂ S than ATCC 51932-inoculated cells.

CONCLUSIONS

H pylori infection modulates endogenous H₂ S production in AGS cells, suggesting that H₂ S might be one of the bioactive molecules involved in the biological mechanisms of gastric mucosal disease including mucosal atrophy.

A redox-based electrogenetic CRISPR system to connect with and control biological information networks

Electronic information can be transmitted to cells directly from microelectronics via electrode-activated redox mediators. These transmissions are decoded by redox-responsive promoters which enable user-specified control over biological function. Here, we build on this redox communication modality by establishing an electronic eCRISPR conduit of information exchange. This system acts as a biological signal processor, amplifying signal reception and filtering biological noise. We electronically amplify bacterial quorum sensing (QS) signaling by activating LasI, the autoinducer-1 synthase. Similarly, we filter out unintended noise by inhibiting the native SoxRS-mediated oxidative stress response regulon. We then construct an eCRISPR based redox conduit in both E. coli and Salmonella enterica. Finally, we display eCRISPR based information processing that allows transmission of spatiotemporal redox commands which are then decoded by gelatin-encapsulated E. coli. We anticipate that redox communication channels will enable biohybrid microelectronic devices that could transform our abilities to electronically interpret and control biological function.

Intestinal gases: influence on gut disorders and the role of dietary manipulations

The inner workings of the intestines, in which the body and microbiome intersect to influence gut function and systemic health, remain elusive. Carbon dioxide, hydrogen, methane and hydrogen sulfide, as well as a variety of trace gases, are generated by the chemical interactions and microbiota within the gut. Profiling of these intestinal gases and their responses to dietary changes can reveal the products and functions of the gut microbiota and their influence on human health. Indeed, different tools for measuring these intestinal gases have been developed, including newly developed gas-sensing capsule technology. Gases can, according to their type, concentration and volume, induce or relieve abdominal symptoms, and might also have physiological, pathogenic and therapeutic effects. Thus, profiling and modulating intestinal gases could be powerful tools for disease prevention and/or therapy. As the interactions between the microbiota, chemical constituents and fermentative substrates of the gut are principally influenced by dietary intake, altering the diet, which, in turn, changes gas profiles, is the main therapeutic approach for gastrointestinal disorders. An improved understanding of the complex interactions within the intestines that generate gases will enhance our ability to prevent, diagnose, treat and monitor many gastrointestinal disorders.