Gut microbiome (Cambridge, England)最新文献

The gut microbiota plays crucial roles in maintaining the health and homeostasis of its host throughout lifespan, including through its ability to impact brain function and regulate behaviour during ageing. Studies have shown that there are disparate rates of biologic ageing despite equivalencies in chronologic age, including in the development of neurodegenerative diseases, which suggests that environmental factors may play an important role in determining health outcomes in ageing. Recent evidence demonstrates that the gut microbiota may be a potential novel target to ameliorate symptoms of brain ageing and promote healthy cognition. This review highlights the current knowledge around the relationships between the gut microbiota and host brain ageing, including potential contributions to age-related neurodegenerative diseases. Furthermore, we assess key areas for which gut microbiota-based strategies may present as opportunities for intervention.

Consumption of probiotics and/or yogurt could be a solution for restoring the balance of the gut microbiota. This study examined associations of regular intake of probiotic supplements or yogurt with the gut microbiota among a diverse population of older adults (N=1,861; 60-72 years). Fecal microbial composition was obtained from 16S rRNA gene sequencing (V1-V3 region). General Linear Models were used to estimate the associations of probiotic supplement or yogurt intake with microbiome measures adjusting for covariates. Compared to non-yogurt consumers (N=1,023), regular yogurt consumers (≥once/week, N=818) had greater Streptococcus (β=0.29, P=0.0003) and lower Odoribacter (β=-0.33, P<0.0001) abundance. The directions of the above associations were consistent across the five ethnic groups but stronger among Japanese Americans (Streptococcus: β=0.56, P=0.0009; Odoribacter: β=-0.62, P=0.0005). Regular intake of probiotic supplements (N=175) was not associated with microbial characteristics (i.e., alpha diversity and the abundance of 152 bacteria genera). Streptococcus is one of the predominant bacteria genera in yogurt products, which may explain the positive association between yogurt consumption and Streptococcus abundance. Our analyses suggest that changes in Odoribacter were independent of changes in Streptococcus abundance. Future studies may investigate whether these microbial genera and their sub-level species mediate potential pathways between yogurt consumption and health.

Research on the gut microbiome has gained high popularity and almost every disease has meanwhile been linked to alterations in microbiome composition. Typically assessed via stool samples, the microbiome displays a huge diversity with a multitude of environmental parameters already identified as contributing to its character. Despite impressive scientific progress, normal microbiome diversity remains largely unexplained and it is tempting to speculate some of the yet unexplained variance is hidden in normal gut physiology. Although a few genome/phenome-wide associations studies have recently highlighted physiological parameters such as stool frequency, known as contributing to microbiome diversity, there is a large knowledge base from decades of basic research on gut functions that can be explored for possible links to stool features and microbiome characteristics. And, when extrapolating findings from faecal samples to the biology in the intestinal lumen or the mucosal microenvironment, gut anatomy and physiology features need to be considered. Similarly, differences in anatomy and physiology between rodents and humans need attention when discussing findings in animals in relation to human physiology and nutrition.

Human milk oligosaccharides (HMOs) are a class of structurally diverse and complex unconjugated glycans present in breast milk, which act as selective substrates for several genera of select microbes and inhibit the colonisation of pathogenic bacteria. Yet, not all infants are breastfed, instead being fed with formula milks which may or may not contain HMOs. Currently, formula milks only possess two HMOs: 2'-fucosyllactose (2'FL) and lacto-N-neotetraose (LNnT), which have been suggested to be similarly effective as human breast milk in supporting age-related growth. However, the in vivo evidence regarding their ability to beneficially reduce respiratory infections along with altering the composition of an infant's microbiota is limited at best. Thus, this review will explore the concept of HMOs and their metabolic fate, and summarise previous in vitro and in vivo clinical data regarding HMOs, with specific regard to 2'FL and LNnT.

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction with a complex pathophysiology. Growing evidence suggests that alterations of the gut microenvironment, including microbiota composition and function, may be involved in symptom generation. Therefore, attempts to modulate the gut microenvironment have provided promising results as an indirect approach for IBS management. Antibiotics, probiotics, prebiotics, food and faecal microbiota transplantation are the main strategies for alleviating IBS symptom severity by modulating gut microbiota composition and function (eg. metabolism), gut barrier integrity and immune activity, although with varying efficacy. In this narrative review, we aim to provide an overview of the current approaches targeting the gut microenvironment in order to indirectly manage IBS symptoms.

Acute appendicitis is a common acute surgical emergency; however, the pathogenesis of adult appendicitis remains poorly understood. The microbiome is increasingly thought to play a key role in inflammatory disease of the bowel and similarly, may play a role in appendicitis. This study aimed to characterise the microbiome of adult acute appendicitis in a prospective cohort. We recruited 60 adults with acute appendicitis and 20 healthy controls. Rectal swabs were taken from each patient. After DNA extraction, 16S rRNA amplicon sequencing was carried out for analysis of diversity and taxonomic abundance. Phylogenetic sequencing of the samples indicated that there is a difference between the microbial composition of those with acute appendicitis and healthy controls, with a statistically significant decrease in alpha diversity in rectal swabs of appendicitis patients compared to healthy controls. At the genus level, we saw an increased abundance of potential pathogens, for example, Parvimonas and Acinetobacter, and a decrease in commensal taxa such as Faecalibacterium, Blautia and Lachnospiraceae in appendicitis patients compared to healthy controls. There was a reduction in diversity and loss of commensals in the microbiome of those with acute appendicitis, which may play a role in the cascade leading to acute appendicitis or the result of this.

Despite extensive research into the toxicology of the herbicide glyphosate, there are still major unknowns regarding its effects on the human gut microbiome. We describe the effects of glyphosate and a Roundup glyphosate-based herbicide on infant gut microbiota using SHIME technology. SHIME microbiota culture was undertaken in the presence of a concentration of 100-mg/L glyphosate and the same glyphosate equivalent concentration of Roundup. Roundup and to a lesser extent glyphosate caused an increase in fermentation activity, resulting in acidification of the microbial environment. This was also reflected by an increase in lactate and acetate production concomitant to a decrease in the levels of propionate, valerate, caproate and butyrate. Ammonium production reflecting proteolytic activities was increased by Roundup exposure. Global metabolomics revealed large-scale disturbances, including an increased abundance of long-chain polyunsaturated fatty acids. Changes in bacterial composition measured by qPCR and 16S rRNA suggested that lactobacilli had their growth stimulated as a result of microenvironment acidification. Co-treatment with the spore-based probiotic formulation MegaSporeBiotic reverted some of the changes in short-chain fatty acid levels. Altogether, our results suggest that glyphosate can exert effects on human gut microbiota.