Gut microbiome and aging nexus and underlying mechanism

The Effects of Dietary Saccharomyces cerevisiae Supplementation on Gut Microbiota Composition and Gut Health in Aged Labrador Retrievers

The intestinal microbiome changes with age, influencing the host's health and immune status. Saccharomyces cerevisiae (S. cerevisiae) positively affects intestinal function in humans and animals, but its effects on gut health and the microbiota profile in aged dogs have not been thoroughly investigated. Twenty aged Labrador Retrievers were divided into two groups: a control group (CON) and a S. cerevisiae group (SC). The experiment lasted for 42 days, with assessments of their intestinal barrier function, inflammatory factors, antioxidant markers, and fecal microbiome composition. The results showed that dietary S. cerevisiae reduced the levels of TNF-α, IL-6, and IL-1β in the serum (p < 0.05). In the SC group, plasma superoxide dismutase and glutathione peroxidase activities increased, while the level of malondialdehyde significantly decreased (p < 0.05). Additionally, dietary S. cerevisiae lowered the serum zonulin and lipopolysaccharide (LPS) levels (p < 0.05) and inhibited fecal ammonia production (p < 0.05). Furthermore, the microbiota profile showed that dietary S. cerevisiae decreased the abundance of Firmicutes but increased the Chao index, the abundance of Bacteroidetes, and the proportion of Bacteroidetes to Firmicutes (p < 0.05). To conclude, dietary S. cerevisiae can regulate the gut's microbial structure and gut health, which may contribute to the overall health of companion animals as they age.

Differential analysis of serum immunology and gut microbiota in patients with gastrointestinal diseases

Objective

Gastric and intestinal diseases possess distinct characteristics although they are interconnected. The primary objective of this study was to investigate the pathogenesis of gastrointestinal diseases through different analyses of clinical characteristics, serum immunology, and gut microbiota in patients with gastrointestinal diseases.

Methods

We collected serum samples from 89 patients with gastrointestinal diseases and 9 healthy controls for immunological assessment, stool samples for DNA extraction, library construction, sequencing, as well as clinical data for subsequent analysis.

Results

Regarding clinical characteristics, there were significant differences between the disease group and the healthy control (HC) group, particularly in terms of age, cancer antigen 125 (CA125), cancer antigen 199 (CA199), alpha-fetoprotein (AFP), total bilirubin (TBIL) and indirect bilirubin (IBIL). The intestinal disease (ID) group exhibited the highest IL-6 level, which significantly differed from the stomach disease (SD) group (p < 0.05). In comparing the HC with the ID groups, significant differences in abundance were detected across 46 species. The HC group displayed a greater abundance of Clostridiales, Clostridia, Firmicutes, Bifidobacterium, Bifidobacteriaceae, Bifidobacteriales, Actinobacteria, Veillonellaceae, Longum, Copri, Megamonas and Callidus than other species. Similarly, when comparing the HC with the SD groups, significant differences in abundance were identified among 49 species, with only one species that the Lachnospiraceae in the HC group exhibited a higher abundance than others. Furthermore, certain clinical characteristics, such as CA125, CA199, glucose (Glu), creatine kinase-MB (CKMB) and interleukin-22 (IL-22), displayed positive correlations with enriched gut species in the ID and SD groups, while exhibiting a negative correlation with the HC group.

Conclusion

The disturbance in human gut microbiota is intimately associated with the development and progression of gastrointestinal diseases. Moreover, the gut microbiota in the HC group was found more diverse than that in the ID and SD groups, and there were significant differences in microbial species among the three groups at different classification levels. Notably, a correlation was identified between specific clinical characteristics (e.g., CA125, CA199, Glu, CKMB and IL-22) and gut microbiota among patients with gastrointestinal diseases.

Structural characteristics of gut microbiota in longevity from Changshou town, Hubei, China

The gut microbiota (GM) and its potential functions play a crucial role in maintaining host health and longevity. The aim of this study was to investigate the potential relationship between GM and longevity. We collected fecal samples from 92 healthy volunteers (middle-aged and elderly: 43-79 years old; longevity: ≥ 90 years old) from Changshou Town, Zhongxiang City, Hubei, China. In addition, we collected samples from 30 healthy middle-aged and elderly controls (aged 51-70 years) from Wuhan, Hubei. The 16S rDNA V3 + V4 region of the fecal samples was sequenced using high-throughput sequencing technology. Diversity analysis results showed that the elderly group with longevity and the elderly group with low body mass index (BMI) exhibited higher α diversity. However, no significant difference was observed in β diversity. The results of the microbiome composition indicate that Firmicutes, Proteobacteria, and Bacteroidota are the core phyla in all groups. Compared to younger elderly individuals, Akkermansia and Lactobacillus are significantly enriched in the long-lived elderly group, while Megamonas is significantly reduced. In addition, a high abundance of Akkermansia is a significant characteristic of elderly populations with low BMI values. Furthermore, the functional prediction results showed that the elderly longevity group had higher abilities in short-chain fatty acid metabolism, amino acid metabolism, and xenobiotic biodegradation. Taken together, our study provides characteristic information on GM in the long-lived elderly population in Changshou Town. This study can serve as a valuable addition to the current research on age-related GM. KEY POINTS: • The gut microbiota of elderly individuals with longevity and low BMI exhibit higher alpha diversity • Gut microbiota diversity did not differ significantly between genders in the elderly population • Several potentially beneficial bacteria (e.g., Akkermansia and Lactobacillus) are enriched in long-lived individuals.

Achieving healthy aging through gut microbiota-directed dietary intervention: Focusing on microbial biomarkers and host mechanisms

BACKGROUND

Population aging has become a primary global public health issue, and the prevention of age-associated diseases and prolonging healthy life expectancies are of particular importance. Gut microbiota has emerged as a novel target in various host physiological disorders including aging. Comprehensive understanding on changes of gut microbiota during aging, in particular gut microbiota characteristics of centenarians, can provide us possibility to achieving healthy aging or intervene pathological aging through gut microbiota-directed strategies.

AIM OF REVIEW

This review aims to summarize the characteristics of the gut microbiota associated with aging, explore potential biomarkers of aging and address microbiota-associated mechanisms of host aging focusing on intestinal barrier and immune status. By summarizing the existing effective dietary strategies in aging interventions, the probability of developing a diet targeting the gut microbiota in future is provided.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review is focused on three key notions: Firstly, gut microbiota has become a new target for regulating health status and lifespan, and its changes are closely related to age. Thus, we summarized aging-associated gut microbiota features at the levels of key genus/species and important metabolites through comparing the microbiota differences among centenarians, elderly people and younger people. Secondly, exploring microbiota biomarkers related to aging and discussing future possibility using dietary regime/components targeted to aging-related microbiota biomarkers promote human healthy lifespan. Thirdly, dietary intervention can effectively improve the imbalance of gut microbiota related to aging, such as probiotics, prebiotics, and postbiotics, but their effects vary among.

Lactobacillus plantarum LLY-606 Supplementation Ameliorates the Cognitive Impairment of Natural Aging in Mice: The Potential Role of Gut Microbiota Homeostasis

This work explored the effects of Lactobacillus plantarum LLY-606 (LLY-606) on cognitive function in aging mice. Our findings demonstrated that LLY-606 effectively prolonged the lifespan of mice and improved age-related cognitive impairments. Additionally, our study revealed that supplementation with LLY-606 resulted in the downregulation of inflammatory cytokine levels and the upregulation of antioxidant capacity. Furthermore, probiotic supplementation effectively mitigated the deterioration of the intestinal barrier function in aging mice. Amplicon analysis indicated the successful colonization of probiotics, facilitating the regulation of age-induced gut microbiota dysbiosis. Notably, the functional abundance prediction of microbiota indicated that tryptophan metabolism pathways, glutamatergic synapse pathways, propanoate metabolism pathways, and arginine and proline metabolism pathways were enriched after the LLY-606 intervention. In summary, LLY-606 emerged as a potential functional probiotic capable of influencing cognitive function in aging mice. This effect was achieved through the modulation of gut microbiota, the regulation of synaptic plasticity, and the enhancement of neurotrophic factor levels.

Selenium- and/or Zinc-Enriched Egg Diet Improves Oxidative Damage and Regulates Gut Microbiota in D-Gal-Induced Aging Mice

Eggs, with their high nutritional value, are great carriers for enriching nutrients. In this study, selenium- and/or zinc-enriched eggs (SZE) were obtained and their effects on ameliorating oxidative stress injury, alleviating cognitive impairment, and maintaining intestinal flora balance in a D-gal-induced aging mice model were investigated. As determined by the Y-maze test, SZE restored the learning and memory abilities and increased the Ach level and AChE activity of aging mice (p < 0.05). Meanwhile, supplementation of low-dose SZE increased antioxidant levels and decreased inflammation levels (p < 0.05). High-dose SZE increased anti-inflammatory levels but were less effective than low dose. Additionally, SZE maintained the intestinal flora balance and significantly increased the ratio of Firmicutes and Bacteroidota. Blautia, as a probiotic, was negatively correlated with pro-inflammatory factors and positively correlated with antioxidant levels (p < 0.05). These results suggest that SZE might improve organ damage and cognitive function by attenuating oxidative stress and inflammatory response and maintaining healthy gut flora.

Gut microbiota: an ideal biomarker and intervention strategy for aging

Population aging is a substantial challenge for the global sanitation framework. Unhealthy aging tends to be accompanied by chronic diseases such as cardiovascular disease, diabetes, and cancer, which undermine the welfare of the elderly. Based on the fact that aging is inevitable but retarding aging is attainable, flexible aging characterization and efficient anti-aging become imperative for healthy aging. The gut microbiome, as the most dynamic component interacting with the organism, can affect the aging process through its own structure and metabolites, thus holding the potential to become both an ideal aging-related biomarker and an intervention strategy. This review summarizes the value of applying gut microbiota as aging-related microbial biomarkers in diagnosing aging state and monitoring the effect of anti-aging interventions, ultimately pointing to the future prospects of microbial intervention strategies in maintaining healthy aging.

Changes in Gut Microbiota Associated with Parity in Large White Sows

As one of the most critical economic traits, the litter performance of sows is influenced by their parity. Some studies have indicated a connection between the gut microbiota and the litter performance of animals. In this study, we examined litter performance in 1363 records of different parities of Large White sows. We observed a marked decline in TNB (Total Number Born) and NBH (Number of Healthy Born) We observed a marked decline in TNB (Total Number Born) and NBH (Number of Healthy Born) among sows with parity 7 or higher. To gain a deeper understanding of the potential role of gut microbiota in this phenomenon, we conducted 16S rRNA amplicon sequencing of fecal DNA from 263 Large White sows at different parities and compared the changes in their gut microbiota with increasing parity. The results revealed that in comparison to sows with a parity from one to six, sows with a parity of seven or higher exhibited decreased alpha diversity in their gut microbiota. There was an increased proportion of pathogenic bacteria (such as Enterobacteriaceae, Streptococcus, and Escherichia-Shigella) and a reduced proportion of SCFA-producing families (such as Ruminococcaceae), indicating signs of inflammatory aging. The decline in sow function may be one of the primary reasons for the reduction in their litter performance.

Lactiplantibacillus plantarum CCFM8661 alleviates D-galactose-induced brain aging in mice by the regulation of the gut microbiota

Aging is characterized by a decline in biological functions, leading to various health issues. There is significant interest in mitigating age and age-related health issues. Gut microbiota has emerged as a crucial target for combating aging and influencing host health. This study evaluated the anti-aging effects of Lactiplantibacillus plantarum CCFM8661 in mice and the role of the gut microbiota in mediating its effects. Aging was induced in mice using D-galactose, and L. plantarum CCFM8661 was orally administered for 8 weeks to evaluate its effects on age-related decline and the gut microbiota. The results demonstrated that supplementation with L. plantarum CCFM8661 effectively alleviated cognitive impairment and oxidative stress in the aging brain, as well as liver oxidation and bone damage, and impaired intestinal barrier function in aging mice. Furthermore, L. plantarum CCFM8661 modulated the gut microbiota of aging mice, increasing the abundance of beneficial bacteria, such as Ruminococcaceae, and influenced the functionality of the gut microbiota to promote the production of active metabolites. These findings suggest that L. plantarum CCFM8661 has a mitigating effect on organismal aging, especially brain aging.

Uterine microbial communities and their potential role in the regulation of epithelium cell cycle and apoptosis in aged hens

BACKGROUND

Alterations of the uterine microbiome are closely associated with various intrauterine diseases and physiological conditions, which are well-established in mammals. However, as representative oviparous animals, the research on the uterine microbial ecosystem and its functions with physiological homeostasis is limited in chickens. Additionally, continuous egg-laying disrupts the oviducal immune defenses of aged hens, susceptible to pathogen invasion, causing poor egg quality and food-borne infections in humans. Here, we investigated aging-related changes in the oviduct microbial colonization and transmission from the gut to eggs and their roles in a hen model.

RESULTS

The results of 16S rDNA sequencing showed significant differences in the oviduct microbial composition between young (38 weeks) and aged (77 weeks) laying hens. SourceTracker analysis further revealed differences in the effects of microbial transmission on the oviducal microbiota between young and aged hens. Enhanced barrier defense with cell apoptosis suppression and cell cycle arrest of the uterus were observed in aged hens reducing microbial transmission from the lower to upper reproductive tract. In addition, a total of 361 significantly differential metabolites were identified using metabolomics in the aged uterine microbiota, especially in products of amino acid metabolism and biosynthesis of various secondary metabolites, which might have essential effects on cell apoptosis by regulating immune responses and cell cycle. Notably, antibiotics disrupted uterine microbiota by dietary intervention and direct perfusion did not retard aging-related physiological changes but further aggravated aging processes by disrupting the cell cycle and apoptosis.

CONCLUSIONS

The microbiota continuum along the reproductive tract in aged birds differs from that in young birds, especially with a significant shift in the uterus. The aged uterine microbiota probably contributes to the regulation of cell cycle and apoptosis by microbial metabolites primarily involved in amino acid metabolism and biosynthesis of various secondary metabolites. These findings provide new insights into the roles of the reproductive tract microbiota in regulating the cell programming of the aged host, contributing to the exploration of the microbiome as a target for diagnosing aging health status and therapy for gynecological diseases in women. Video Abstract.

Gut microbiota-derived short chain fatty acids act as mediators of the gut-brain axis targeting age-related neurodegenerative disorders: a narrative review

Neurodegenerative diseases associated with aging are often accompanied by cognitive decline and gut microbiota disorder. But the impact of gut microbiota on these cognitive disturbances remains incompletely understood. Short chain fatty acids (SCFAs) are major metabolites produced by gut microbiota during the digestion of dietary fiber, serving as an energy source for gut epithelial cells and/or circulating to other organs, such as the liver and brain, through the bloodstream. SCFAs have been shown to cross the blood-brain barrier and played crucial roles in brain metabolism, with potential implications in mediating Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanisms that SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, the dietary sources which determine these SCFAs production was not thoroughly evaluated yet. This comprehensive review explores the production of SCFAs by gut microbiota, their transportation through the gut-brain axis, and the potential mechanisms by which they influence age-related neurodegenerative disorders. Also, the review discusses the importance of dietary fiber sources and the challenges associated with harnessing dietary-derived SCFAs as promoters of neurological health in elderly individuals. Overall, this study suggests that gut microbiota-derived SCFAs and/or dietary fibers hold promise as potential targets and strategies for addressing age-related neurodegenerative disorders.

High-Throughput Sequencing Reveals a Dynamic Bacterial Linkage between the Captive White Rhinoceros and Its Environment

Soil is an essential part of the animal habitat and has a large diversity of microbiota, while the animal body was colonized by a complex bacterial community; so far, the relationship between the animal host microbial community and the soil microbial ecosystem remains largely unknown. In this study, 15 white rhinoceros from three different captive grounds were selected and the bacterial community of the gut, skin, and environment of these rhinoceros were analyzed by 16S rRNA sequencing technology. Our results showed that Firmicutes and Bacteroidota were the predominant phyla in the gut microbiome, whereas skin and environment samples share similar microbiome profiles and are dominated by the phyla of Actinobacteriota, Chloroflexi, and Proteobacteria. Although the bacterial composition of the gut differs from that of the skin and environment, the Venn diagrams showed that there were 22 phyla and 186 genera shared by all the gut, skin, and environmental microbes in white rhinoceroses. Further cooccurrence network analysis indicated a bacterial linkage based on a complex interaction was established by the bacterial communities from the three different niches. In addition, beta diversity and bacterial composition analysis showed that both the captive ground and host ages induced shifts in the microbial composition of white rhinoceroses, which suggested that the bacterial linkage between the captive white rhinoceros and its environment is dynamic. Overall, our data contribute to a better understanding of the bacterial community of the captive white rhinoceros, especially for the relationship between the environment and animal bacterial communities. IMPORTANCE The white rhinoceros is one of the world's most endangered mammals. The microbial population plays a key role in animal health and welfare; however, studies regarding the microbial communities of the white rhinoceros are relatively limited. As the white rhinoceros has a common behavior of mud baths and thus is in direct contact with the environment, a relationship between the animal microbial community and the soil microbial ecosystem appears possible, but it remains unclear. Here, we described the characteristics and interaction of bacterial communities of the white rhinoceros in three different niches, including gut, skin, and environment. We also analyzed the effects of captive ground and age on the composition of the bacterial community. Our findings highlighted the relationship among the three niches and may have important implications for the conservation and management of this threatened species.

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.

Gut microbiota enhance energy accumulation of black-necked crane to cope with impending migration

Less is known about the role of gut microbiota in overwintering environmental adaptation in migratory birds. Here, we performed metagenomic sequencing on fresh fecal samples (n = 24) collected during 4 periods of overwintering (Dec: early; Jan: middle I; Feb: middle II; Mar: late) to characterize gut microbial taxonomic and functional characteristics of black-necked crane (Grus nigricollis). The results demonstrated no significant change in microbial diversity among overwintering periods. Analysis of compositions of microbiomes with bias correction (ANCOM-BC) determined 15 Proteobacteria species enriched in late overwintering period. Based on previous reports, these species are associated with degradation of chitin, cellulose, and lipids. Meanwhile, fatty acid degradation and betalain biosynthesis pathways are enriched in late overwintering period. Furthermore, metagenomic binning obtained 91 high-quality bins (completeness >70% and contamination <10%), 5 of which enriched in late overwintering period. Carnobacterium maltaromaticum, unknown Enterobacteriaceae, and Yersinia frederiksenii have genes for chitin and cellulose degradation, acetate, and glutamate production. Unknown Enterobacteriaceae and Y. frederiksenii hold genes for synthesis of 10 essential amino acids required by birds, and the latter has genes for γ-aminobutyrate production. C. maltaromaticum has genes for pyridoxal synthesis. These results implied the gut microbiota is adapted to the host diet and may help black-necked cranes in pre-migratory energy accumulation by degrading the complex polysaccharide in their diet, supplying essential amino acids and vitamin pyridoxal, and producing acetate, glutamate, and γ-aminobutyrate that could stimulate host feeding. Additionally, enriched Proteobacteria also encoded more carbohydrate-active enzymes (CAZymes) and antibiotic resistance genes (ARGs) in late overwintering period. KEY POINTS: • Differences in gut microbiota function during overwintering period of black-necked cranes depend mainly on changes in core microbiota abundance • Gut microbiota of black-necked crane adapted to the diet during overwintering period • Gut microbiota could help black-necked cranes to accumulate more energy in the late overwintering period.

Physical Activity and Diet in Older Women: A Narrative Review

Physical activity and diet are essential for maintaining good health and preventing the development of non-communicable diseases, especially in the older adults. One aspect that is often over-looked is the different response between men and women to exercise and nutrients. The body's response to exercise and to different nutrients as well as the choice of foods is different in the two sexes and is strongly influenced by the different hormonal ages in women. The present narrative review analyzes the effects of gender on nutrition and physical activity in older women. Understanding which components of diet and physical activity affect the health status of older women would help target non-pharmacological but lifestyle-related therapeutic interventions. It is interesting to note that this analysis shows a lack of studies dedicated to older women and a lack of studies dedicated to the interactions between diet and physical activity in women. Gender medicine is a current need that still finds little evidence.

Association between Microbiome-Related Human Genetic Variants and Fasting Plasma Glucose in a High-Cardiovascular-Risk Mediterranean Population

Background and Objectives: The gut microbiota has been increasingly recognized as a relevant factor associated with metabolic diseases. However, directly measuring the microbiota composition is a limiting factor for several studies. Therefore, using genetic variables as proxies for the microbiota composition is an important issue. Landmark microbiome–host genome-wide association studies (mbGWAS) have identified many SNPs associated with gut microbiota. Our aim was to analyze the association between relevant microbiome-related genetic variants (Mi-RSNPs) and fasting glucose and type 2 diabetes in a Mediterranean population, exploring the interaction with Mediterranean diet adherence. Materials and Methods: We performed a cross-sectional study in a high-cardiovascular-risk Mediterranean population (n = 1020), analyzing the association of Mi-RSNPs (from four published mbGWAS) with fasting glucose and type 2 diabetes. A single-variant approach was used for fitting fasting glucose and type 2 diabetes to a multivariable regression model. In addition, a Mendelian randomization analysis with multiple variants was performed as a sub-study. Results: We obtained several associations between Mi-RSNPs and fasting plasma glucose involving gut Gammaproteobacteria_HB, the order Rhizobiales, the genus Rumminococcus torques group, and the genus Tyzzerella as the top ranked. For type 2 diabetes, we also detected significant associations with Mi-RSNPs related to the order Rhizobiales, the family Desulfovibrionaceae, and the genus Romboutsia. In addition, some Mi-RSNPs and adherence to Mediterranean diet interactions were detected. Lastly, the formal Mendelian randomization analysis suggested combined effects. Conclusions: Although the use of Mi-RSNPs as proxies of the microbiome is still in its infancy, and although this is the first study analyzing such associations with fasting plasma glucose and type 2 diabetes in a Mediterranean population, some interesting associations, as well as modulations, with adherence to the Mediterranean diet were detected in these high-cardiovascular-risk subjects, eliciting new hypotheses.