Comparative Analysis of Gut Microbiota in Centenarians and Young People: Impact of Eating Habits and Childhood Living Environment

Anti-aging effects of Lacticaseibacillus paracasei PS117 on cognitive and intestinal health in naturally-aged mice: A focus on senescence-related proteins and microbiota composition

The rising global aging population underscores the urgency of maintaining the health and well-being of the elderly while reducing the healthcare burden. Anti-aging probiotics have emerged as a promising strategy. This study identified a novel anti-senescence probiotic, Lacticaseibacillus paracasei PS117 (PS117). The effects of PS117 and heat-treated PS117 (HT-PS117) supplementation on cognitive function of naturally-aged male mice were investigated. It was found that PS117 supplementation improved the cognitive performance of aged mice in the Y-maze test. Furthermore, the level of senescence-related protein p16INK4a (p16) were reduced, while anti-senescence protein sirtuin 1 (Sirt1) were increased in the hippocampus. In addition, there was an overall improvement in the intestinal function. Distinct changes in the gut microbiota were also identified, suggesting a potential contribution to the beneficial effects of PS117 supplementation. In conclusion, these results suggest that PS117 supplements could improve cognitive and intestinal functions in naturally-aged mice, while HT-117 improves only intestinal function, possibly by improving the gut microbiota composition.

Dysbiosis promotes recurrence of adenomatous polyps in the distal colorectum

BACKGROUND

Colorectal polyps, which are characterized by a high recurrence rate, represent preneoplastic conditions of the intestine. Due to unclear mechanisms of pathogenesis, first-line therapies for non-hereditary recurrent colorectal polyps are limited to endoscopic resection. Although recent studies suggest a mechanistic link between intestinal dysbiosis and polyps, the exact compositions and roles of bacteria in the mucosa around the lesions, rather than feces, remain unsettled.

AIM

To clarify the composition and diversity of bacteria in the mucosa surrounding or 10 cm distal to recurrent intestinal polyps.

METHODS

Mucosal samples were collected from four patients consistently with adenomatous polyps (Ade), seven consistently with non-Ade (Pol), ten with current Pol but previous Ade, and six healthy individuals, and bacterial patterns were evaluated by 16S rDNA sequencing. Linear discriminant analysis and Student's t-tests were used to identify the genus-level bacteria differences between groups with different colorectal polyp phenotypes. Pearson's correlation coefficients were used to evaluate the correlation between intestinal bacteria at the genus level and clinical indicators.

RESULTS

The results confirmed a decreased level of probiotics and an enrichment of pathogenic bacteria in patients with all types of polyps compared to healthy individuals. These changes were not restricted to the mucosa within 0.5 cm adjacent to the polyps, but also existed in histologically normal tissue 10 cm distal from the lesions. Significant differences in bacterial diversity were observed in the mucosa from individuals with normal conditions, Pol, and Ade. Increased abundance of Gram-negative bacteria, including Klebsiella, Plesiomonas, and Cronobacter, was observed in Pol group and Ade group, suggesting that resistance to antibiotics may be one risk factor for bacterium-related harmful environment. Meanwhile, age and gender were linked to bacteria changes, indicating the potential involvement of sex hormones.

CONCLUSION

These preliminary results support intestinal dysbiosis as an important risk factor for recurrent polyps, especially adenoma. Targeting specific pathogenic bacteria may attenuate the recurrence of polyps.

The role of Bifidobacterium in longevity and the future of probiotics

This review explores the role and health impacts of probiotics, focusing specifically on Bifidobacterium spp. It highlights the functionalities that Bifidobacteria can provide, underscored by the historical evolution of definitions and technological advancements related to probiotics. By examining the association between Bifidobacteria and longevity, this review suggests new avenues for health enhancement. Highlighting case studies of centenarians, it presents examples related to human aging, illuminating the potential links to longevity through research on Bifidobacterium strains found in centenarians. This review not only emphasizes the importance of current research but also advocates for further investigation into the health benefits of Bifidobacteria, underlining the necessity for continuous study in the nutraceutical field.

Unraveling the Microbiome-Human Body Axis: A Comprehensive Examination of Therapeutic Strategies, Interactions and Implications

This review scrutinizes the intricate interplay between the microbiome and the human body, exploring its multifaceted dimensions and far-reaching implications. The human microbiome, comprising diverse microbial communities inhabiting various anatomical niches, is increasingly recognized as a critical determinant of human health and disease. Through an extensive examination of current research, this review elucidates the dynamic interactions between the microbiome and host physiology across multiple organ systems. Key topics include the establishment and maintenance of microbiota diversity, the influence of host factors on microbial composition, and the bidirectional communication pathways between microbiota and host cells. Furthermore, we delve into the functional implications of microbiome dysbiosis in disease states, emphasizing its role in shaping immune responses, metabolic processes, and neurological functions. Additionally, this review discusses emerging therapeutic strategies aimed at modulating the microbiome to restore host-microbe homeostasis and promote health. Microbiota fecal transplantation represents a groundbreaking therapeutic approach in the management of dysbiosis-related diseases, offering a promising avenue for restoring microbial balance within the gut ecosystem. This innovative therapy involves the transfer of fecal microbiota from a healthy donor to an individual suffering from dysbiosis, aiming to replenish beneficial microbial populations and mitigate pathological imbalances. By synthesizing findings from diverse fields, this review offers valuable insights into the complex relationship between the microbiome and the human body, highlighting avenues for future research and clinical interventions.

Oral microbial signatures associated with age and frailty in Canadian adults

This study aimed to assess the association between the oral microbiome, age, and frailty. Data and saliva samples were obtained from male and female participants aged 35-70 years (n = 1357). Saliva samples were analysed by 16S rRNA gene sequencing and differences in microbial diversity and community compositions were examined in relation to chronological age and the frailty index (FI). Most alpha diversity measures (Richness, Shannon Diversity, Faith's Phylogenetic Diversity) showed an inverse association with frailty, whereas a positive association was observed with age and Shannon Diversity and Evenness. A further sex-stratified analysis revealed differences in measures of microbial diversity and composition. Multiple genera were detected as significantly differentially abundant with increasing frailty and age by at least two methods. With age, the relative abundance of Veillonella was reduced in both males and females, whereas increases in Corynebacterium appeared specific to males and Aggregatibacter, Fusobacterium, Neisseria, Stomatobaculum, and Porphyromonas specific to females. Beta diversity was significantly associated with multiple mental health components of the FI. This study shows age and frailty are differentially associated with measures of microbial diversity and composition, suggesting the oral microbiome may be a useful indicator of increased risk of frailty or a potential target for improving health in ageing adults.

Developing the Common Marmoset as a Translational Geroscience Model to Study the Microbiome and Healthy Aging

Emerging data support associations between the depletion of the healthy gut microbiome and aging-related physiological decline and disease. In humans, fecal microbiota transplantation (FMT) has been used successfully to restore gut microbiome structure and function and to treat C. difficile infections, but its application to healthy aging has been scarcely investigated. The marmoset is an excellent model for evaluating microbiome-mediated changes with age and interventional treatments due to their relatively shorter lifespan and many social, behavioral, and physiological functions that mimic human aging. Prior work indicates that FMT is safe in marmosets and may successfully mediate gut microbiome function and host health. This narrative review (1) provides an overview of the rationale for FMT to support healthy aging using the marmoset as a translational geroscience model, (2) summarizes the prior use of FMT in marmosets, (3) outlines a protocol synthesized from prior literature for studying FMT in aging marmosets, and (4) describes limitations, knowledge gaps, and future research needs in this field.

Networks of gut bacteria relate to cardiovascular disease in a multi-ethnic population: the HELIUS study

AIMS

Gut microbiota have been linked to blood lipid levels and cardiovascular diseases (CVDs). The composition and abundance of gut microbiota trophic networks differ between ethnicities. We aim to evaluate the relationship between gut microbiotal trophic networks and CVD phenotypes.

METHODS AND RESULTS

We included cross-sectional data from 3860 individuals without CVD history from 6 ethnicities living in the Amsterdam region participating in the prospective Healthy Life in Urban Setting (HELIUS) study. Genetic variants were genotyped, faecal gut microbiota were profiled, and blood and anthropometric parameters were measured. A machine learning approach was used to assess the relationship between CVD risk (Framingham score) and gut microbiota stratified by ethnicity. Potential causal relationships between gut microbiota composition and CVD were inferred by performing two-sample Mendelian randomization with hard CVD events from the Pan-UK Biobank and microbiome genome-wide association studies summary data from a subset of the HELIUS cohort (n = 4117). Microbial taxa identified to be associated with CVD by machine learning and Mendelian randomization were often ethnic-specific, but some concordance across ethnicities was found. The microbes Akkermansia muciniphila and Ruminococcaceae UCG-002 were protective against ischaemic heart disease in African-Surinamese and Moroccans, respectively. We identified a strong inverse association between blood lipids, CVD risk, and the combined abundance of the correlated microbes Christensenellaceae-Methanobrevibacter-Ruminococcaceae (CMR). The CMR cluster was also identified in two independent cohorts and the association with triglycerides was replicated.

CONCLUSION

Certain gut microbes can have a potentially causal relationship with CVD events, with possible ethnic-specific effects. We identified a trophic network centred around Christensenellaceae, Methanobrevibacter, and various Ruminococcaceae, frequently lacking in South-Asian Surinamese, to be protective against CVD risk and associated with low triglyceride levels.

The gut metabolite 3-hydroxyphenylacetic acid rejuvenates spermatogenic dysfunction in aged mice through GPX4-mediated ferroptosis

BACKGROUND

Aging-related fertility decline is a prevalent concern globally. Male reproductive system aging is mainly characterized by a decrease in sperm quality and fertility. While it is known that intestinal physiology changes with age and that microbiota is shaped by physiology, the underlying mechanism of how the microbiota affects male reproductive aging is still largely unexplored.

RESULTS

Here, we utilized fecal microbiota transplantation (FMT) to exchange the fecal microbiota between young and old mice. Cecal shotgun metagenomics and metabolomics were used to identify differences in gut microbiota composition and metabolic regulation during aging. Our results demonstrated that FMT from young to old mice alleviated aging-associated spermatogenic dysfunction through an unexpected mechanism mediated by a gut bacteria-derived metabolite, 3-hydroxyphenylacetic acid (3-HPAA). 3-HPAA treatment resulted in an improvement of spermatogenesis in old mice. RNA sequencing analysis, qRT-PCR and Western blot revealed that 3-HPAA induced an upregulation of GPX4, thereby restraining ferroptosis and restoring spermatogenesis. These findings were further confirmed by in vitro induction of ferroptosis and inhibition of GPX4 expression.

CONCLUSIONS

Our results demonstrate that the microbiome-derived metabolite, 3-HPAA, facilitates spermatogenesis of old mice through a ferroptosis-mediated mechanism. Overall, these findings provide a novel mechanism of dysregulated spermatogenesis of old mice, and suggest that 3-HPAA could be a potential therapy for fertility decline of aging males in clinical practice. Video Abstract.

Gut microbiota and anti-aging: Focusing on spermidine

The human gut microbiota plays numerous roles in regulating host growth, the immune system, and metabolism. Age-related changes in the gut environment lead to chronic inflammation, metabolic dysfunction, and illness, which in turn affect aging and increase the risk of neurodegenerative disorders. Local immunity is also affected by changes in the gut environment. Polyamines are crucial for cell development, proliferation, and tissue regeneration. They regulate enzyme activity, bind to and stabilize DNA and RNA, have antioxidative properties, and are necessary for the control of translation. All living organisms contain the natural polyamine spermidine, which has anti-inflammatory and antioxidant properties. It can regulate protein expression, prolong life, and improve mitochondrial metabolic activity and respiration. Spermidine levels experience an age-related decrease, and the development of age-related diseases is correlated with decreased endogenous spermidine concentrations. As more than just a consequence, this review explores the connection between polyamine metabolism and aging and identifies advantageous bacteria for anti-aging and metabolites they produce. Further research is being conducted on probiotics and prebiotics that support the uptake and ingestion of spermidine from food extracts or stimulate the production of polyamines by gut microbiota. This provides a successful strategy to increase spermidine levels.

Exploring the Relationship between the Gut Microbiota and Ageing: A Possible Age Modulator

The gut microbiota (GM) has been the subject of intense research in recent years. Therefore, numerous factors affecting its composition have been thoroughly examined, and with them, their function and role in the individual's systems. The gut microbiota's taxonomical composition dramatically impacts older adults' health status. In this regard, it could either extend their life expectancy via the modulation of metabolic processes and the immune system or, in the case of dysbiosis, predispose them to age-related diseases, including bowel inflammatory and musculoskeletal diseases and metabolic and neurological disorders. In general, the microbiome of the elderly tends to present taxonomic and functional changes, which can function as a target to modulate the microbiota and improve the health of this population. The GM of centenarians is unique, with the faculty-promoting metabolic pathways capable of preventing and counteracting the different processes associated with age-related diseases. The molecular mechanisms by which the microbiota can exhibit anti-ageing properties are mainly based on anti-inflammatory and antioxidant actions. This review focuses on analysing the current knowledge of gut microbiota characteristics and modifiers, its relationship with ageing, and the GM-modulating approaches to increase life expectancy.

The Crosstalk between Gut Microbiota and White Adipose Tissue Mitochondria in Obesity

Adipose tissue (AT) dysregulation is a key process in the pathophysiology of obesity and its cardiometabolic complications, but even if a growing body of evidence has been collected over recent decades, the underlying molecular basis of adiposopathy remains to be fully understood. In this context, mitochondria, the intracellular organelles that orchestrate energy production and undergo highly dynamic adaptive changes in response to changing environments, have emerged as crucial regulators of both white (WAT) and brown adipose tissue (BAT) metabolism and function. Given that the gut microbiota and its metabolites are able to regulate host metabolism, adipogenesis, WAT inflammation, and thermogenesis, we hypothesize that their frequently observed dysregulation in obesity could affect AT metabolism by exerting direct and indirect effects on AT mitochondria. By collecting and revising the current evidence on the connections between gut microbiota and AT mitochondria in obesity, we gained insights into the molecular biology of their hitherto largely unexplored crosstalk, tracing how gut microbiota may regulate AT mitochondrial function.

Longevity-Associated Core Gut Microbiota Mining and Effect of Mediated Probiotic Combinations on Aging Mice: Case Study of a Long-Lived Population in Guangxi, China

With an ageing population, healthy longevity is becoming an important scientific concern. The longevity phenomenon is closely related to the intestinal microflora and is highly complicated; it is challenging to identify and define the core gut microbiota associated with longevity. Therefore, in this study, 16S rRNA sequencing data were obtained from a total of 135 faecal samples collected as part of the latest sampling and pre-collection initiative in the Guangxi longevity area, and weighted gene co-expression network analysis (WGCNA) was used to find a mediumpurple3 network module significantly associated with the Guangxi longevity phenomenon. Five core genera, namely, Alistipes, Bacteroides, Blautia, Lachnospiraceae NK4A136 group, and Lactobacillus, were identified via network analysis and random forest (RF) in this module. Two potential probiotic strains, Lactobacillus fermentum and Bacteroides fragilis, were further isolated and screened from the above five core genera, and then combined and used as an intervention in naturally ageing mice. The results show a change in the key longevity gut microbiota in mice toward a healthy longevity state after the intervention. In addition, the results show that the probiotic combination effectively ameliorated anxiety and necrosis of hippocampal neuronal cells in senescent mice, improving their antioxidant capacity and reducing their inflammation levels. In conclusion, this longer-term study provides a new approach to the search for longevity hub microbiota. These results may also provide an important theoretical reference for the healthification of the intestinal microflora in the general population, and even the remodelling of the structure of the longevity-state intestinal microflora.

The effects of traditional Chinese medicine and dietary compounds on digestive cancer immunotherapy and gut microbiota modulation: A review

Digestive tract-related cancers account for four of the top ten high-risk cancers worldwide. In recent years, cancer immunotherapy, which exploits the innate immune system to attack tumors, has led to a paradigm shifts in cancer treatment. Gut microbiota modification has been widely used to regulate cancer immunotherapy. Dietary compounds and traditional Chinese medicine (TCM) can alter the gut microbiota and its influence on toxic metabolite production, such as the effect of iprindole on lipopolysaccharide (LPS), and involvement in various metabolic pathways that are closely associated with immune reactions. Therefore, it is an effective strategy to explore new immunotherapies for gastrointestinal cancer to clarify the immunoregulatory effects of different dietary compounds/TCMs on intestinal microbiota. In this review, we have summarized recent progress regarding the effects of dietary compounds/TCMs on gut microbiota and their metabolites, as well as the relationship between digestive cancer immunotherapy and gut microbiota. We hope that this review will act as reference, providing a theoretical basis for the clinical immunotherapy of digestive cancer via gut microbiota modulation.

Intestinal microbiome in normal ageing, frailty and cognition decline

PURPOSE OF REVIEW

The intestinal microbiome modulates the risk of several age-related chronic diseases and syndromes, including frailty and neurodegenerative diseases. Herein we provided an update on the influence of gut microbiota on physical and cognitive performance in older age and suggest microbiota-targeted interventions for healthy ageing.

RECENT FINDINGS

Low uniqueness index of the gut microbiome and high representation of Bacteroides are independently associated with mortality in older individuals, while the centenarian microbiome is characterized by high abundance of Lactobacilli and Bifidobacteria . Frailty syndrome, sarcopenia and cognitive decline are associated with reduced faecal microbiota biodiversity, reduced abundance of bacteria able to synthetize short-chain fatty acids (SCFA), including Faecalibacterium prausnitzii , and reduced faecal butyrate levels. Dietary intervention, especially involving Mediterranean diet, and exercise training seem to be associated with improved biodiversity of the microbiota, increased capacity of SCFA synthesis and, probably, protection against the onset of frailty and cognitive decline.

SUMMARY

The gut microbiota biodiversity and composition may reflect the different ageing trajectory, but further research is needed to understand potential independent and combined effects of environmental and lifestyle factors in older adults, especially from a clinical point of view.

Gut microbiota as an antioxidant system in centenarians associated with high antioxidant activities of gut-resident Lactobacillus

The gut microbiota plays an important role in human health and longevity, and the gut microbiota of centenarians shows unique characteristics. Nowadays, most microbial research on longevity is usually limited to the bioinformatics level, lacking validating information on culturing functional microorganisms. Here, we combined metagenomic sequencing and large-scale in vitro culture to reveal the unique gut microbial structure of the world's longevity town-Jiaoling, China, centenarians and people of different ages. Functional strains were isolated and screened in vitro, and the possible relationship between gut microbes and longevity was explored and validated in vivo. 247 healthy Cantonese natives of different ages participated in the study, including 18 centenarians. Compared with young adults, the gut microbiota of centenarians exhibits higher microbial diversity, xenobiotics biodegradation and metabolism, oxidoreductases, and multiple species (the potential probiotics Lactobacillus, Akkermansia, the methanogenic Methanobrevibacter, gut butyrate-producing members Roseburia, and SCFA-producing species uncl Clostridiales, uncl Ruminococcaceae) known to be beneficial to host metabolism. These species are constantly changing with age. We also isolated 2055 strains from these samples by large-scale in vitro culture, most of which were detected by metagenomics, with clear complementarity between the two approaches. We also screened an age-related gut-resident Lactobacillus with independent intellectual property rights, and its metabolite (L-ascorbic acid) and itself have good antioxidant effects. Our findings underscore the existence of age-related trajectories in the human gut microbiota, and that distinct gut microbiota and gut-resident as antioxidant systems may contribute to health and longevity.

Interventions on Gut Microbiota for Healthy Aging

In recent years, the improvement in health and social conditions has led to an increase in the average lifespan. Since aging is the most important risk factor for the majority of chronic human diseases, the development of therapies and intervention to stop, lessen or even reverse various age-related morbidities is an important target to ameliorate the quality of life of the elderly. The gut microbiota, that is, the complex ecosystem of microorganisms living in the gastrointestinal tract, plays an important role, not yet fully understood, in maintaining the host's health and homeostasis, influencing metabolic, oxidative and cognitive status; for this reason, it is also named "the forgotten endocrine organ" or "the second brain". On the other hand, the gut microbiota diversity and richness are affected by unmodifiable factors, such as aging and sex, and modifiable ones, such as diet, pharmacological therapies and lifestyle. In this review, we discuss the changes, mostly disadvantageous, for human health, induced by aging, in microbiota composition and the effects of dietary intervention, of supplementation with probiotics, prebiotics, synbiotics, psychobiotics and antioxidants and of physical exercise. The development of an integrated strategy to implement microbiota health will help in the goal of healthy aging.

Influential factors of saliva microbiota composition

The oral microbiota is emerging as an influential factor of host physiology and disease state. Factors influencing oral microbiota composition have not been well characterised. In particular, there is a lack of population-based studies. We undertook a large hypothesis-free study of the saliva microbiota, considering potential influential factors of host health (frailty; diet; periodontal disease), demographics (age; sex; BMI) and sample processing (storage time), in a sample (n = 679) of the TwinsUK cohort of adult twins. Alpha and beta diversity of the saliva microbiota was associated most strongly with frailty (alpha diversity: β = -0.16, Q = 0.003, Observed; β = -0.16, Q = 0.002, Shannon; β = -0.16, Q = 0.003, Simpson; Beta diversity: Q = 0.002, Bray Curtis dissimilarity) and age (alpha diversity: β = 0.15, Q = 0.006, Shannon; β = 0.12, Q = 0.003, Simpson; beta diversity: Q = 0.002, Bray Curtis dissimilarity; Q = 0.032, Weighted UniFrac) in multivariate models including age, frailty, sex, BMI, frailty and diet, and adjustment for multiple testing. Those with a more advanced age were more likely to be dissimilar in the saliva microbiota composition than younger participants (P = 5.125e-06, ANOVA). In subsample analyses, including consideration of periodontal disease (total n = 138, periodontal disease n = 66), the association with frailty remained for alpha diversity (Q = 0.002, Observed ASVs; Q = 0.04 Shannon Index), but not beta diversity, whilst age was not demonstrated to associate with alpha or beta diversity in this subsample, potentially due to insufficient statistical power. Length of time that samples were stored prior to sequencing was associated with beta diversity (Q = 0.002, Bray Curtis dissimilarity). Six bacterial taxa were associated with age after adjustment for frailty and diet. Of the factors studied, frailty and age emerged as the most influential with regards to saliva microbiota composition. Whilst age and frailty are correlates, the associations were independent of each other, giving precedence to both biological and chronological ageing as processes of potential importance when considering saliva microbiota composition.

A gut-centric view of aging: Do intestinal epithelial cells contribute to age-associated microbiota changes, inflammaging, and immunosenescence?

Intestinal epithelial cells (IECs) serve as both a physical and an antimicrobial barrier against the microbiota, as well as a conduit for signaling between the microbiota and systemic host immunity. As individuals age, the balance between these systems undergoes a myriad of changes due to age-associated changes to the microbiota, IECs themselves, immunosenescence, and inflammaging. In this review, we discuss emerging data related to age-associated loss of intestinal barrier integrity and posit that IEC dysfunction may play a central role in propagating age-associated alterations in microbiota composition and immune homeostasis.