The last decade has witnessed a growing appreciation of the fundamental role played by an early assembly of a diverse and balanced gut microbiota and its subsequent maintenance for future health of ...the host. Gut microbiota is currently viewed as a key regulator of a fluent bidirectional dialogue between the gut and the brain(gut-brain axis). A number of preclinical studies have suggested that the microbiota and its genome(microbiome) may play a key role in neurodevelopmental and neurodegenerative disorders. Furthermore, alterations in the gut microbiota composition in humans have also been linked to a variety of neuropsychiatric conditions, including depression, autism and Parkinson’s disease. However, it is not yet clear whether these changes in the microbiome are causally related to such diseases or are secondary effects thereof. In this respect, recent studies in animals have indicated that gut microbiota transplantation can transfer a behavioral phenotype, suggesting that the gut microbiota may be a modifiable factor modulating the development or pathogenesis of neuropsychiatric conditions. Further studies are warranted to establish whether or not the findings of preclinical animal experiments can be generalized to humans. Moreover, although different communication routes between the microbiota and brain have been identified, further studies must elucidate all the underlying mechanisms involved. Such research is expected to contribute to the design of strategies to modulate the gut microbiota and its functions with a view to improving mental health, and thus provide opportunities to improve the management of psychiatric diseases. Here, we review the evidence supporting a role of the gut microbiota in neuropsychiatric disorders and the state of the art regarding the mechanisms underlying its contribution to mental illness and health. We also consider the stages of life where the gut microbiota is more susceptible to the effects of environmental stressors, and the possible microbiota-targeted intervention strategies that could improve health status and prevent psychiatric disorders in the near future.
The role of intestinal dysbiosis in obesity-associated systemic inflammation via the cross-talk with peripheral tissues is under debate. Our objective was to decipher the mechanisms by which ...intervention in the gut ecosystem with a specific Bifidobacterium strain reduces systemic inflammation and improves metabolic dysfunction in obese high-fat diet (HFD) fed mice.
Adult male wild-type C57BL-6 mice were fed either a standard or HFD, supplemented with placebo or Bifidobacterium pseudocatenulatum CECT 7765, for 14 weeks. Lymphocytes, macrophages and cytokine/chemokine concentrations were quantified in blood, gut, liver and adipose tissue using bead-based multiplex assays. Biochemical parameters in serum were determined by ELISA and enzymatic assays. Histology was assessed by hematoxylin-eosin staining. Microbiota was analyzed by 16S rRNA gene pyrosequencing and quantitative PCR.
B. pseudocatenulatum CECT 7765 reduced obesity-associated systemic inflammation by restoring the balance between regulatory T cells (Tregs) and B lymphocytes and reducing pro-inflammatory cytokines of adaptive (IL-17A) and innate (TNF-α) immunity and endotoxemia. In the gut, the bifidobacterial administration partially restored the HFD-induced alterations in microbiota, reducing abundances of Firmicutes and of LPS-producing Proteobacteria, paralleled to reductions in B cells, macrophages, and cytokines (IL-6, MCP-1, TNF-α, IL-17A), which could contribute to systemic effects. In adipose tissue, bifidobacterial administration reduced B cells whereas in liver the treatment increased Tregs and shifted different cytokines (MCP-1 plus ILP-10 in adipose tissue and INF-γ plus IL-1β in liver). In both tissues, the bifidobacteria reduced pro-inflammatory macrophages and, TNF-α and IL-17A concentrations. These effects were accompanied by reductions in body weight gain and in serum cholesterol, triglyceride, glucose and insulin levels and improved oral glucose tolerance and insulin sensitivity in obese mice.
Here, we provide evidence of the immune cellular mechanisms by which the inflammatory cascade associated with diet-induced obesity is attenuated by the administration of a specific Bifidobacterium strain and that these effects are associated with modulation of gut microbiota structure.
Diet is a major environmental factor influencing gut microbiota diversity and functionality, which might be relevant to subjects following dietary therapies. Celiac disease (CD) is an enteropathy ...caused by an aberrant immune response to cereal gluten proteins and the only therapy is the adherence to a gluten-free diet (GFD). In this context, a preliminary study was conducted to establish whether the GFD in itself could modify the composition and immune properties of the gut microbiota. The trial included 10 healthy subjects (30.3 years old), which were submitted to a GFD over 1 month. Analysis of fecal microbiota and dietary intake indicated that numbers of healthy gut bacteria decreased, while numbers of unhealthy bacteria increased parallel to reductions in the intake of polysaccharides after following the GFD. Fecal samples of subjects under a GFD, which represent an altered microbiota, also exerted lower immune stimulatory effects on peripheral blood mononuclear cells than those of subjects on a regular gluten-containing diet. This addendum presents further discussion on the rationale behind these findings, limitations of the study and possible consequences of dietary counseling in the care process of celiac disease patients.
Associations have been made between obesity and reduced intestinal numbers of members of the phylum Bacteroidetes, but there is no direct evidence of the role these bacteria play in obesity. Herein, ...the effects of Bacteroides uniformis CECT 7771 on obesity-related metabolic and immune alterations have been evaluated.
Adult (6-8 week) male wild-type C57BL-6 mice were fed a standard diet or a high-fat-diet HFD to induce obesity, supplemented or not with B. uniformis CECT 7771 for seven weeks. Animal weight was monitored and histologic, biochemical, immunocompetent cell functions, and features of the faecal microbiota were analysed after intervention. The oral administration of B. uniformis CECT 7771 reduced body weight gain, liver steatosis and liver cholesterol and triglyceride concentrations and increased small adipocyte numbers in HFD-fed mice. The strain also reduced serum cholesterol, triglyceride, glucose, insulin and leptin levels, and improved oral tolerance to glucose in HFD fed mice. The bacterial strain also reduced dietary fat absorption, as indicated by the reduced number of fat micelles detected in enterocytes. Moreover, B. uniformis CECT 7771 improved immune defence mechanisms, impaired in obesity. HFD-induced obesity led to a decrease in TNF-α production by peritoneal macrophages stimulated with LPS, conversely, the administration of B. uniformis CECT 7771 increased TNF-α production and phagocytosis. Administering this strain also increased TNF-α production by dendritic cells (DCs) in response to LPS stimulation, which was significantly reduced by HFD. B. uniformis CECT 7771 also restored the capacity of DCs to induce a T-cell proliferation response, which was impaired in obese mice. HFD induced marked changes in gut microbiota composition, which were partially restored by the intervention.
Altogether, the findings indicate that administration of B. uniformis CECT 7771 ameliorates HFD-induced metabolic and immune dysfunction associated with intestinal dysbiosis in obese mice.
Plants, animals and humans, are colonized by microorganisms (microbiota) and transiently exposed to countless others. The microbiota affects the development and function of essentially all organ ...systems, and contributes to adaptation and evolution, while protecting against pathogenic microorganisms and toxins. Genetics and lifestyle factors, including diet, antibiotics and other drugs, and exposure to the natural environment, affect the composition of the microbiota, which influences host health through modulation of interrelated physiological systems. These include immune system development and regulation, metabolic and endocrine pathways, brain function and epigenetic modification of the genome. Importantly, parental microbiotas have transgenerational impacts on the health of progeny.
Humans, animals and plants share similar relationships with microbes. Research paradigms from humans and other mammals, amphibians, insects, planktonic crustaceans and plants demonstrate the influence of environmental microbial ecosystems on the microbiota and health of organisms, and indicate links between environmental and internal microbial diversity and good health. Therefore, overlapping compositions, and interconnected roles of microbes in human, animal and plant health should be considered within the broader context of terrestrial and aquatic microbial ecosystems that are challenged by the human lifestyle and by agricultural and industrial activities.
Here, we propose research priorities and organizational, educational and administrative measures that will help to identify safe microbe-associated health-promoting modalities and practices. In the spirit of an expanding version of “One health” that includes environmental health and its relation to human cultures and habits (EcoHealth), we urge that the lifestyle-microbiota-human health nexus be taken into account in societal decision making.
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•Microbiotas of humans, animals and plants influence the hosts' physiology and health.•Microbe biodiversity is linked to health and to transgenerational benefit to progeny.•Humans, animals, plants and the environment continuously exchange microbiota.•Microbiotas can be damaged by antibiotics, agri/industrial chemicals, and lifestyle.•The lifestyle-microbiota-human health nexus must influence societal decision making.
Studies indicate that dietary fat quantity and quality influence the gut microbiota composition which may as a consequence impact metabolic health. This systematic review aims to summarize the ...results of available studies in humans on dietary fat intake (quantity and quality), the intestinal microbiota composition and related cardiometabolic health outcomes.
We performed a systematic review (CRD42018088685) following PRISMA guidelines and searched for literature in Medline, EMBASE, and Cochrane databases.
From 796 records, 765 records were excluded based on title or abstract. After screening of 31 full-text articles six randomized controlled trials (RCT) and nine cross-sectional observational studies were included. Our results of interventional trials do not suggest strong effects of different amounts and types of dietary fat on the intestinal microbiota composition or on metabolic health outcomes while observational studies indicate associations with the microbiota and health outcomes. High intake of fat and saturated fatty acids (SFA) may negatively affect microbiota richness and diversity and diets high in monounsaturated fatty acids (MUFA) may decrease total bacterial numbers whereas dietary polyunsaturated fatty acids (PUFA) had no effect on richness and diversity.
High fat and high SFA diets can exert unfavorable effects on the gut microbiota and are associated with an unhealthy metabolic state. Also high MUFA diets may negatively affect gut microbiota whereas PUFA do not seem to negatively affect the gut microbiota or metabolic health outcomes. However, data are not consistent and most RCT and observational studies showed risks of bias.
Obesity is a major public health issue as it is causally related to several chronic disorders, including type-2 diabetes, CVD and cancer. Novel research shows that the gut microbiota is involved in ...obesity and metabolic disorders, revealing that obese animal and human subjects have alterations in the composition of the gut microbiota compared to their lean counterparts. Moreover, transplantation of the microbiota of either obese or lean mice influences body weight in the germ-free recipient mice, suggesting that the gut ecosystem is a relevant target for weight management. Indigenous gut microbes may regulate body weight by influencing the host's metabolic, neuroendocrine and immune functions. The intestinal microbiota, as a whole, provides additional metabolic functions and regulates the host's gene expression, improving the ability to extract and store energy from the diet and contributing to body-weight gain. Imbalances in the gut microbiota and increases in plasma lipopolysaccharide may also act as inflammatory factors related to the development of atherosclerosis, insulin resistance and body-weight gain. In contrast, specific probiotics, prebiotics and related metabolites might exert beneficial effects on lipid and glucose metabolism, the production of satiety peptides and the inflammatory tone related to obesity and associated metabolic disorders. This knowledge is contributing to our understanding of how environmental factors influence obesity and associated diseases, providing new opportunities to design improved dietary intervention strategies to manage these disorders.
For the last decades, nanocomposites materials have been widely studied in the scientific literature as they provide substantial properties enhancements, even at low nanoparticles content. Their ...performance depends on a number of parameters but the nanoparticles dispersion and distribution state remains the key challenge in order to obtain the full nanocomposites' potential in terms of, e.g., flame retardance, mechanical, barrier and thermal properties, etc., that would allow extending their use in the industry. While the amount of existing research and indeed review papers regarding the formulation of nanocomposites is already significant, after listing the most common applications, this review focuses more in-depth on the properties and materials of relevance in three target sectors: packaging, solar energy and automotive. In terms of advances in the processing of nanocomposites, this review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion. In the case of nanocoatings, it describes the different conventionally used processes as well as nanoparticles deposition by electro-hydrodynamic processing. All in all, this review gives the basics both in terms of composition and of processing aspects to reach optimal properties for using nanocomposites in the selected applications. As an outlook, up-to-date nanosafety issues are discussed.
Alimentary and endogenous proteins are mixed in the small intestinal lumen with the microbiota. Although experimental evidences suggest that the intestinal microbiota is able to incorporate and ...degrade some of the available amino acids, it appears that the microbiota is also able to synthesize amino acids raising the view that amino acid exchange between the microbiota and host can proceed in both directions. Although the net result of such exchanges remains to be determined, it is likely that a significant part of the amino acids recovered from the alimentary proteins are used by the microbiota. In the large intestine, where the density of bacteria is much higher than in the small intestine and the transit time much longer, the residual undigested luminal proteins and peptides can be degraded in amino acids by the microbiota. These amino acids cannot be absorbed to a significant extent by the colonic epithelium, but are precursors for the synthesis of numerous metabolic end products in reactions made by the microbiota. Among these products, some like short-chain fatty acids and organic acids are energy substrates for the colonic mucosa and several peripheral tissues while others like sulfide and ammonia can affect the energy metabolism of colonic epithelial cells. More work is needed to clarify the overall effects of the intestinal microbiota on nitrogenous compound metabolism and consequences on gut and more generally host health.
This paper investigates whether lockdown policies aggravated mental health problems of older populations (50 and over) in Europe during the first COVID-19 wave. Using data from the Survey of Health, ...Ageing and Retirement in Europe (SHARE COVID-19 questionnaire) and from the Oxford COVID-19 Government Response Tracker for 17 countries, we estimate the causal effect of lockdown policies on mental health by combining cross-country variability in the strictness of the policies with cross-individual variability in face-to-face contacts prior to the pandemic. We find that lockdown policies worsened insomnia, anxiety, and depression by 5, 7.2 and 5.1 percentage points, respectively. This effect was stronger for women and those aged between 50 and 65. Interestingly, lockdown policies notably damaged the mental health of healthy populations. We close with a discussion of lockdown policies targeted at individuals above 65 and/or with pre-existing conditions.
•We estimate the causal effect of lockdown policies on mental health of older populations.•We focus on the worsening of 3 mental outcomes: insomnia, anxiety and depression.•We use data from SHARE COVID-19 survey and from OXCGRT for 17 European countries.•We find that lockdown policies caused significant increase of mental health problems.•We find stronger causal effects for women and those between 50 and 65 years old.
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