Tout savoir sur les post-biotiques

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Metabolites and mechanisms involved in microbiota-host interactions
Maria do Carmo Gouveia Peluzio Trends in Food Science & Technology Volume 108, February 2021, Pages 11-26

Highlights
• Postbiotics provide therapeutic benefits, preserve the integrity and improve the balance of the host microbiome.
• Iron, calcium, phosphorus, and zinc are dependent on bacteria for the processes of absorption and/or maintenance in the body.
• Bacteriocins from lactic acid bacteria have low or no cytotoxicity,can inhibit the growth of enteropathogenic bacteria.
• Postbiotics are involved in the regulation of the immune, neurological, and physiological systems.


Abstract
Background
The knowledge on the mechanisms through which the metabolites produced by the gut microbiota (postbiotics) prevent diseases, induce therapeutic responses, and behave differently in response to dietary and environmental changes, is one of the major challenges in nutrition research and paves the route for the development of new therapeutic strategies against non-communicable diseases.

Scope and approach
In this review, the main mechanisms by which postbiotics provide a link between nutrition, microbiota, and human health are discussed. Postbiotics are the repertoire of metabolites produced in the fermentation process of dietary components (mainly fibers and polyphenols, but also complex carbohydrates, proteins, and lipids), as well as the endogenous components generated by bacteria-host interactions that influence human health.

Key findings and conclusions
Short-chain fatty acids denote a primary energy source for colonocytes, also acting on the gut-brain axis to reduce appetite and performing epigenetic roles. Polyamines promote homeostasis and affect epigenetic processes, apoptosis, and cell proliferation through interaction with proteins and nucleic acids. Bile acids are involved in glucose metabolism and modulation of the host immune response. p-Cresol features antimicrobial and antioxidant properties, but has been related to enteric pathogens, autism, and kidney diseases. The role of trimethylamine N-oxide (TMAO) in cardiovascular diseases is still under debate. Bacteriocins have antibiotic action against pathogens. The beneficial effects of polyphenols are demonstrated by their essentiality in the production of metabolites. Summarizing, metagenomic sequencing, intervention studies, and metabolomics are enabling to understand the modulation and effects of microbiota metabolic activity. However, in order to clearly elucidate the food-microbiota axis, the interplay among the host microbiota and the metabolites secreted by intestinal cells, and the intestine-liver-brain axis, the studies must be directed to the subject habitat.

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Bioactive peptides and gut microbiota: Candidates for a novel strategy for reduction and control of neurodegenerative diseases
Shujian Wu Trends in Food Science & Technology Volume 108, February 2021, Pages 164-176

Highlights
• Crosstalk exists between brain and gut microbiota via the gut-brain axis.
• ROS has a dual role in the regulation of gut and gut microbiota.
• Peptides modulate the ROS balance in the gut and the composition of gut microbiota.
• Peptides influence the brain via the microbiota-gut-brain axis.
• Strategies in the production and modification of peptides affect their bioactivity.

Background
Neurodegenerative diseases are debilitating conditions that diminish the quality of life and pose significant financial and social burdens. Therefore, strategies to relieve and control these diseases are urgently required, which will improve the quality of patients’ lives. Dysbacteriosis of gut microbiota has been shown to be a key component of neurodegenerative disease etiology. The homeostasis of gut microbiota and the balance of reactive oxygen species (ROS) in the gut can be altered by bioactive peptides derived from food sources. Therefore, biopeptides that improve neurodegenerative diseases by regulating gut microbiota have received considerable attention.

Scope and approach
The impact of gut microbiota on the brain through the gut-brain axis has been summarized. Additionally, the dual role of ROS in regulating the homeostasis of gut and gut microbiota and the function of bioactive peptides in ameliorating neurodegenerative diseases via the microbiota-gut-brain axis are discussed. Potential strategies for the production and modification of peptides to improve their bioactivity are also highlighted.

Key findings and conclusions
Increasing evidence supports that the gut microbiota modulates neurodegenerative diseases. Bioactive peptides that modulate the gut microbiota can be used as novel and strategic molecules to control and reduce neurodegenerative diseases. The bioactivity of the peptides can be dramatically influenced by different production and modification strategies.

Strategies for further development of functional foods to ameliorate neurodegenerative diseases by regulating the gut microbiota are available. Future work should focus on the bioavailability and interactions of bioactive peptides and their impact on neurodegenerative diseases.

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Review article: Probiotics, prebiotics and dietary approaches during COVID-19 pandemic
Jielun Hu Trends in Food Science & Technology Volume 108, February 2021, Pages 187-196

Highlights
• SARS-CoV-2 infection resulted in immune dysfunction and gut microbiota alterations.
• Probiotics or prebiotics could improve host immune functions during the infection.
• Enhance gut barrier by diversified diet was recommended during COVID-19 pandemic.

Background
Patients with COVID-19 caused by SARS-CoV-2 exhibit diverse clinical manifestations and severity including enteric involvement. Commensal gut bacteria can contribute to defense against potential pathogens by promoting beneficial immune interactions. Interventions targeting the gut microbiome may have systemic anti-viral effects in SARS-CoV-2 infection.

Scope and approach
To summarise alterations of gut microbiota in patients with COVID-19 including impact of specific bacteria on disease severity, discuss current knowledge on the role of probiotics, prebiotics and dietary approaches including vitamin D in preventing and reducing disease susceptibility and review clinical studies using probiotics to target coronavirus. A literature review on SARS-CoV-2, COVID-19, gut microbiome and immunity was undertaken and relevant literature was summarised and critically examined.

Key findings and conclusions
Integrity of gut microbiome was perturbed in SARS-CoV-2 infections and associated with disease severity. Poor prognosis in SARS-CoV-2 infection was observed in subjects with underlying co-morbidities who had increased gut permeability and reduced gut microbiome diversity. Dietary microbes, including probiotics or selected prebiotics of Chinese origin, had anti-viral effects against other forms of coronavirus, and could positively impact host immune functions during SARS-CoV-2 infection. Numerous studies are investigating the role of probiotics in preventing and reducing susceptibility to SARS-CoV-2 infection in healthcare workers, household contacts and affected patients. An approach to strengthen intestinal barrier and lower pro-inflammatory states by adopting a more diversified diet during COVID-19 pandemic.

SARS-CoV-2 infection is associated with immune dysfunction and gut microbiota alterations. Delineating mechanisms of probiotics, prebiotics and diet with anti-SARS-CoV-2 immunity present opportunities for discovery of microbial therapeutics to prevent and treat COVID-19.

[Nutrimuscle-Conseils]

Gut microbiota-derived metabolite trimethylamine N-oxide as a biomarker in early Parkinson's disease
Seok Jong Chung Nutrition Volume 83, March 2021, 111090

Highlights
• Plasma trimethylamine N-oxide (TMAO) level was decreased in patients with Parkinson's disease (PD) compared with healthy controls
• PD group with high TMAO levels received lower doses of dopaminergic medications
• PD group with high TMAO levels tended to have a lower risk for PDD conversion
• Changes in plasma TMAO levels can be a potential prognostic biomarker in PD

Objectives
This study aimed to investigate the potential of using changes in the plasma levels of trimethylamine N-oxide (TMAO), a gut microbiota-derived metabolite, as a biomarker in early Parkinson's disease (PD).

Methods
Plasma TMAO levels were measured in 85 patients with drug-naïve early stage PD and 20 healthy controls. A linear mixed model was used to assess longitudinal changes in levodopa-equivalent dose (LED) during follow-up (>2 y) in three tertile PD groups according to plasma TMAO levels. Additionally, a Cox regression analysis was performed to assess the effect of plasma TMAO levels on dementia conversion.

Results
Plasma TMAO levels of patients with PD were lower than those of healthy controls. A linear mixed model demonstrated that patients with PD and lower levels of TMAO (<4.75 μmol/L; i.e., lowest tertile group) exhibited faster increases in LED over time. The Cox regression model did not reveal that plasma TMAO level was associated with the risk for dementia conversion (P = 0.488). However, when we divided patients with PD into two subgroups according to bet cutoff TMAO level to maximize the log-rank statistics, the PD group with a low plasma TMAO level (<6.92 μmol/L) had a higher risk (with borderline statistical significance) for PD–dementia conversion than the group with a high TMAO level (hazard ratio: 7.565; 95% confidence interval, 1.004−57.019; P = 0.050).

Conclusions
The results demonstrate that lower baseline plasma TMAO levels are associated with faster increases in LED and tend to increase the risk for PD–dementia conversion, suggesting the prognostic implications of TMAO in early stage PD.

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Role of brain-gut-muscle axis in human health and energy homeostasis
Yunju Yin Front. Nutr., 06 October 2022

The interrelationship between brain, gut and skeletal muscle plays a key role in energy homeostasis of the body, and is becoming a hot topic of research. Intestinal microbial metabolites, such as short-chain fatty acids (SCFAs), bile acids (BAs) and tryptophan metabolites, communicate with the central nervous system (CNS) by binding to their receptors.

In fact, there is a cross-talk between the CNS and the gut. The CNS, under the stimulation of pressure, will also affect the stability of the intestinal system, including the local intestinal transport, secretion and permeability of the intestinal system. After the gastrointestinal tract collects information about food absorption, it sends signals to the central system through vagus nerve and other channels to stimulate the secretion of brain-gut peptide and produce feeding behavior, which is also an important part of maintaining energy homeostasis. Skeletal muscle has receptors for SCFAs and BAs.

Therefore, intestinal microbiota can participate in skeletal muscle energy metabolism and muscle fiber conversion through their metabolites. Skeletal muscles can also communicate with the gut system during exercise. Under the stimulation of exercise, myokines secreted by skeletal muscle causes the secretion of intestinal hormones, and these hormones can act on the central system and affect food intake. The idea of the brain-gut-muscle axis is gradually being confirmed, and at present it is important for regulating energy homeostasis, which also seems to be relevant to human health.

This article focuses on the interaction of intestinal microbiota, central nervous, skeletal muscle energy metabolism, and feeding behavior regulation, which will provide new insight into the diagnostic and treatment strategies for obesity, diabetes, and other metabolic diseases.

[Nutrimuscle-Diététique]

Traduction de l'étude

Rôle de l'axe cerveau-intestin-muscle dans la santé humaine et l'homéostasie énergétique
Front Yunju Yin. Nutr., 06 octobre 2022

L'interrelation entre le cerveau, l'intestin et le muscle squelettique joue un rôle clé dans l'homéostasie énergétique du corps et devient un sujet de recherche brûlant. Les métabolites microbiens intestinaux, tels que les acides gras à chaîne courte (SCFA), les acides biliaires (BA) et les métabolites du tryptophane, communiquent avec le système nerveux central (SNC) en se liant à leurs récepteurs.

En fait, il existe une interaction entre le SNC et l'intestin. Le SNC, sous la stimulation de la pression, affectera également la stabilité du système intestinal, y compris le transport intestinal local, la sécrétion et la perméabilité du système intestinal. Une fois que le tractus gastro-intestinal a collecté des informations sur l'absorption des aliments, il envoie des signaux au système central via le nerf vague et d'autres canaux pour stimuler la sécrétion du peptide cerveau-intestin et produire un comportement alimentaire, qui est également un élément important du maintien de l'homéostasie énergétique. Le muscle squelettique possède des récepteurs pour les SCFA et les BA.

Par conséquent, le microbiote intestinal peut participer au métabolisme énergétique des muscles squelettiques et à la conversion des fibres musculaires via leurs métabolites. Les muscles squelettiques peuvent également communiquer avec le système intestinal pendant l'exercice. Sous la stimulation de l'exercice, les myokines sécrétées par le muscle squelettique provoquent la sécrétion d'hormones intestinales, et ces hormones peuvent agir sur le système central et affecter la prise alimentaire. L'idée de l'axe cerveau-intestin-muscle se confirme progressivement et est aujourd'hui importante pour la régulation de l'homéostasie énergétique, qui semble également pertinente pour la santé humaine.

Cet article se concentre sur l'interaction du microbiote intestinal, du métabolisme énergétique des muscles nerveux centraux et squelettiques et de la régulation du comportement alimentaire, ce qui fournira de nouvelles informations sur les stratégies de diagnostic et de traitement de l'obésité, du diabète et d'autres maladies métaboliques.