The gut microbiome and frailty

Diminished representation of vitamin-B12-producing bacteria in constipated elders with frailty

Constipation and frailty are associated with intestinal dysbiosis. This study aims to identify intestinal microbial signatures that can differentiate between constipated elders accompanied by frailty and those without frailty. We collected stool samples from 61 participants and conducted 16S rRNA gene sequencing. Constipated patients with frailty (Constipation_F) exhibited reduced gut microbial diversities compared to constipated patients without frailty (Constipation_NF) and healthy individuals (C). From differential genera, random forest models identified 14, 8, and 5 biomarkers for distinguishing Constipation_F from Constipation_NF, Constipation_F from C, and Constipation_NF from C, respectively. Functional analysis revealed that pathways (P381-PWY and PWY-5507) related to vitamin B12 synthesis were reduced in Constipation_F, which aligns with the decreased abundances of vitamin-B12-producing Actinomyces and Akkermansia in this group. Our study unveils substantial differences in gut microbiota between constipated elders with frailty and those without, underscoring the diagnostic and therapeutic potential of genera involved in vitamin B12 synthesis.

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.

Association of dietary live microbe intake with frailty in US adults: evidence from NHANES

OBJECTIVE

Diets rich in live microbes can bring various health benefits. However, the association between dietary live microbe intake and frailty has not been studied.

METHODS

The study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. A total of 11,529 participants were included. Sanders et al. classified the level of live microbes in foods into low (<104 CFU/g), medium (104-107 CFU/g), or high (>107 CFU/g). With the methodology of Sanders et al. and dietary questionnaire data, participants were divided into three groups: (1) low dietary live microbe intake group (only low-level foods), (2) medium dietary live microbe intake group (medium but not high-level foods), and (3) high dietary live microbe intake group (any high-level foods). Additionally, foods with medium and high live microbe content were aggravated as MedHi. Frailty index ≥0.25 is defined as frailty. The weighted logistic regression analysis was conducted to examine the relationship between the intake of dietary live microbe and frailty. The restricted cubic splines (RCS) were employed to detect the nonlinear relationships.

RESULTS

In the fully adjusted model, participants with high dietary intake of live microbe had a significantly lower risk of frailty than those with low dietary intake of live microbe (OR = 0.67, 95% CI: 0.56, 0.79). For every 100 grams of MedHi food consumed, the risk of frailty decreased by 11% (OR = 0.89, 95% CI: 0.85, 0.92) after adjusting all covariates. The RCS indicated the existence of non-linear relationships. For those who consumed less than 100 grams of MedHi, increasing MedHi intake may significantly reduce the risk of frailty, but after exceeding 100 grams, the curve gradually levels off.

CONCLUSIONS

Our results suggested that increasing dietary live microbe intake was associated with a lower risk of frailty. However, more research is needed to verify this.

Comparison of the Fecal Bacteriome of HIV-Positive and HIV-Negative Older Adults

HIV infection is considered a scenario of accelerated aging. Previous studies have suggested a link between aging, frailty, and gut dysbiosis, but there is a knowledge gap regarding the HIV population. Our objective was to compare the fecal bacteriome of older people with HIV (PWH) and non-HIV controls, and to assess potential links between gut dysbiosis and frailty. A total of 36 fecal samples (24 from PWH and 12 from non-HIV controls) were submitted to a metataxonomic analysis targeting the V3-V4 hypervariable region of the 16S rRNA gene. High-quality reads were assembled and classified into operational taxonomic units. Alpha diversity, assessed using the Shannon index, was higher in the control group than in the HIV group (p < 0.05). The relative abundance of the genus Blautia was higher in the HIV group (p < 0.001). The presence of Blautia was also higher in PWH with depression (p = 0.004), whereas the opposite was observed for the genus Bifidobacterium (p = 0.004). Our study shows shifts in the composition of the PWH bacteriome when compared to that of healthy controls. To our knowledge, this is the first study suggesting a potential link between depression and gut dysbiosis in the HIV population.

Intestinal microbial 16S sequencing and LC-MS metabonomic analysis revealed differences between young and old cats

With the progress of society, the health problems of pets have attracted more and more attention. Recent studies have shown that intestinal microflora and related fecal metabolites play a crucial role in the healthy growth of cats. However, the potential role and related metabolic characteristics of gut microbiota in different age groups of pet cats need to be further clarified. 16S rRNA gene sequencing was used to analyze the intestinal microbial composition of young and old cats. LC-MS metabonomic analysis is used to characterize the changes in the metabolic spectrum in feces. The potential relationship between intestinal microorganisms and metabolites, as well as the differences in different age groups, were studied. The species composition of intestinal microflora in the young group and old group is significantly different, T-test algorithm shows 36 different ASVs and 8 different genuses, while the Wilcoxon algorithm shows 81 different ASVs and 17 different genuses. The metabolomics analysis identified 537 kinds of fecal metabolites, which are rich in differences between young and old cats, and may be potential biomarkers indicating the health of cats. 16S rRNA analysis showed significant differences in fructose and mannose metabolism, while metabonomics KEGG analysis showed significant difference in choline metabolism in cancer. Our study compared the differences between the intestinal microbiome and fecal metabolites in young and old cats. This difference provides a new direction for further exploring the relationship between the composition and metabolism of intestinal microbiota in cats of different age groups. It also provides a reference for cat health research.

The Implication of the Gut Microbiome in Heart Failure

Heart failure is a worldwide health problem with important consequences for the overall wellbeing of affected individuals as well as for the healthcare system. Over recent decades, numerous pieces of evidence have demonstrated that the associated gut microbiota represent an important component of human physiology and metabolic homeostasis, and can affect one's state of health or disease directly, or through their derived metabolites. The recent advances in human microbiome studies shed light on the relationship between the gut microbiota and the cardiovascular system, revealing its contribution to the development of heart failure-associated dysbiosis. HF has been linked to gut dysbiosis, low bacterial diversity, intestinal overgrowth of potentially pathogenic bacteria and a decrease in short chain fatty acids-producing bacteria. An increased intestinal permeability allowing microbial translocation and the passage of bacterial-derived metabolites into the bloodstream is associated with HF progression. A more insightful understanding of the interactions between the human gut microbiome, HF and the associated risk factors is mandatory for optimizing therapeutic strategies based on microbiota modulation and offering individualized treatment. The purpose of this review is to summarize the available data regarding the influence of gut bacterial communities and their derived metabolites on HF, in order to obtain a better understanding of this multi-layered complex relationship.

The Gut Microbiome and Its Implication in the Mucosal Digestive Disorders

The gastrointestinal (GI) tract is one of the most studied compartments of the human body as it hosts the largest microbial community including trillions of germs. The relationship between the human and its associated flora is complex, as the microbiome plays an important role in nutrition, metabolism and immune function. With a dynamic composition, influenced by many intrinsic and extrinsic factors, there is an equilibrium maintained in the composition of GI microbiota, translated as "eubiosis". Any disruption of the microbiota leads to the development of different local and systemic diseases. This article reviews the human GI microbiome's composition and function in healthy individuals as well as its involvement in the pathogenesis of different digestive disorders. It also highlights the possibility to consider flora manipulation a therapeutic option when treating GI diseases.

Innovations in the veterinary intestinal health field: A patent landscape analysis

In recent years it has become evident that a healthy intestinal microbiome is beneficial for the overall health of an individual. A healthy microbiome is diverse, increasing stability and resilience and strengthening the immune system. In addition, healthy intestinal metabolisms have a beneficial effect on many physiological processes such as the brain function.

Looking from the One Health perspective, which recognizes that health of humans is closely connected to the health of animals and environment, it is inherently beneficial to stimulate the health of animals for the well-being of humans. However, the intensive administration of antibiotics to livestock for prevention and cure of disease, and even stimulation of growth, disrupts a healthy microbiome. With the rapid increase of emerging zoonotic diseases, alternatives to the use of antimicrobial compounds are urgently necessary. This research analyses the development of alternatives for antibiotic use contributing to veterinary intestinal health through an in-depth patent analysis of inventions for fodder additives. In the period 1999–2020, 1269 unique patent families describing the use of probiotics, enzymes and prebiotics for swine, poultry and ruminants were identified. Innovation trends, geography, key applicants, and classification of patents were analysed.

Asian industrial applicants applied for the majority of patents comprising the largest share of patents for probiotics and enzymes in combination with fodder for swine. Followed by North American and European industrial applications, applying for patents for probiotics in combination with fodder for poultry, swine, and ruminants. Overall, our results do not show a clear increase in innovations, suggesting that innovations in the use of probiotics and enzymes in animal feed appear to be stalling. While in the near future a combination of the use of antibiotics and alternatives is most likely to be implemented, the use of probiotics stands a good chance of replacing antibiotics in animal husbandry and limiting the adverse effects of antibiotic abuse.

•

Alternatives for antibiotic use contributing to veterinary intestinal health are slowly coming to the market.

•

Patent applications for probiotics, prebiotics, enzymes supporting a healthy veterinary intestine are stabilizing.

•

China, as largest applicant for patents targeting the VIH,vcombines probiotics and enzymes with fodder for swine and poultry.

Frailty and postoperative urinary tract infection

BACKGROUND

Among older adults, postoperative urinary tract infection is associated with significant harms including increased risk of hospital readmission and perioperative mortality. While risk of urinary tract infection is known to increase with age, the independent association between frailty and postoperative urinary tract infection is unknown. In this study we used 2014-2018 data from the U.S. National Surgical Quality Improvement Program (NSQIP) to investigate whether frailty is an independent risk factor for postoperative urinary tract infection, controlling for age and other relevant confounders.

METHODS

Frailty was assessed using the modified Frailty Index. Postoperative urinary tract infection was defined as any symptomatic urinary tract infection (of the kidneys, ureters, bladder, or urethra) developing within 30 days of the operative procedure. To examine associations between frailty and other specific factors and postoperative urinary tract infection, chi squared tests, students t-tests, and logistic regression modelling were used.

RESULTS

Urinary tract infection was identified after 22,356 of 1,724,042 procedures (1.3%). In a multivariable model controlling for age and other patient and surgical characteristics, the relative odds for urinary tract infection increased significantly with increasing frailty score. For example, compared to a frailty score of 0, the relative odds for urinary tract infection for a frailty score of 3 was 1.50 (95% confidence interval 1.41, 1.60). The relative odds associated with the maximum frailty score (5) was 2.50 (95% confidence interval 1.73, 3.61).

CONCLUSIONS

Frailty is associated with postoperative urinary tract infection, independent of age. Further research should focus on the underlying mechanisms and strategies to mitigate this risk among frail adults.

The gut microbiome as a modulator of healthy ageing

The gut microbiome is a contributory factor in ageing-related health loss and in several non-communicable diseases in all age groups. Some age-linked and disease-linked compositional and functional changes overlap, while others are distinct. In this Review, we explore targeted studies of the gut microbiome of older individuals and general cohort studies across geographically distinct populations. We also address the promise of the targeted restoration of microorganisms associated with healthier ageing.

Age-related diseases, therapies and gut microbiome: A new frontier for healthy aging

The gut microbiome is undoubtedly a key modulator of human health, which can promote or impair homeostasis throughout life. This is even more relevant in old age, when there is a gradual loss of function in multiple organ systems, related to growth, metabolism, and immunity. Several studies have described changes in the gut microbiome across age groups up to the extreme limits of lifespan, including maladaptations that occur in the context of age-related conditions, such as frailty, neurodegenerative diseases, and cardiometabolic diseases. The gut microbiome can also interact bi-directionally with anti-age-related disease therapies, being affected and in turn influencing their efficacy. In this framework, the development of integrated microbiome-based intervention strategies, aimed at favoring a eubiotic configuration and trajectory, could therefore represent an innovative approach for the promotion of healthy aging and the achievement of longevity.

The Many Ages of Microbiome–Gut–Brain Axis

Frailty during aging is an increasing problem associated with locomotor and cognitive decline, implicated in poor quality of life and adverse health consequences. Considering the microbiome–gut–brain axis, we investigated, in a longitudinal study, whether and how physiological aging affects gut microbiome composition in wild-type male mice, and if and how cognitive frailty is related to gut microbiome composition. To assess these points, we monitored mice during aging at five selected experimental time points, from adulthood to senescence. At all selected experimental times, we monitored cognitive performance using novel object recognition and emergence tests and measured the corresponding Cognitive Frailty Index. Parallelly, murine fecal samples were collected and analyzed to determine the respective alpha and beta diversities, as well as the relative abundance of different bacterial taxa. We demonstrated that physiological aging significantly affected the overall gut microbiome composition, as well as the relative abundance of specific bacterial taxa, including Deferribacterota, Akkermansia, Muribaculaceae, Alistipes, and Clostridia VadinBB60. We also revealed that 218 amplicon sequence variants were significantly associated to the Cognitive Frailty Index. We speculated that some of them may guide the microbiome toward maladaptive and dysbiotic conditions, while others may compensate with changes toward adaptive and eubiotic conditions.

Targeting the gut to prevent and counteract metabolic disorders and pathologies during aging

Impairment of gut function is one of the explanatory mechanisms of health status decline in elderly population. These impairments involve a decline in gut digestive physiology, metabolism and immune status, and associated to that, changes in composition and function of the microbiota it harbors. Continuous deteriorations are generally associated with the development of systemic dysregulations and ultimately pathologies that can worsen the initial health status of individuals. All these alterations observed at the gut level can then constitute a wide range of potential targets for development of nutritional strategies that can impact gut tissue or associated microbiota pattern. This can be key, in a preventive manner, to limit gut functionality decline, or in a curative way to help maintaining optimum nutrients bioavailability in a context on increased requirements, as frequently observed in pathological situations. The aim of this review is to give an overview on the alterations that can occur in the gut during aging and lead to the development of altered function in other tissues and organs, ultimately leading to the development of pathologies. Subsequently is discussed how nutritional strategies that target gut tissue and gut microbiota can help to avoid or delay the occurrence of aging-related pathologies.

Impact of sucroferric oxyhydroxide on the oral and intestinal microbiome in hemodialysis patients

Hyperphosphatemia is a consequence of chronic kidney disease associated with mineral/bone impairment, increased cardiovascular events and mortality. Therapeutically, most dialysis patients have to take phosphate binders. Here, we investigated effects of the Fe(3+)-based phosphate binder sucroferric oxyhydroxide (SFOH) on the oral and gastrointestinal microbiome of 11 hemodialysis patients. Saliva, dental plaque and stool were collected at baseline, one and four weeks of SFOH intake and subjected to 16S rRNA gene (V3-V4 region) directed Illumina MiSeq-based analysis. Total Fe, Fe(2+) and Fe(3+) were determined in stool and saliva. Overall, the microbiome did not change significantly. However, some patient-, sample- and taxon-specific differences were noted, which allowed patients to be divided into those with a shift in their microbiome (6/11) and those without a shift (5/11). Total Fe and Fe(2+) were highest after one week of SFOH, particularly in patients who exhibited a shift in microbiome composition. Eight bacterial taxa showed significant unidirectional changes during treatment. In-depth microbiome analysis revealed that taxa that significantly benefited from iron plethora had no iron-binding siderophores or alternatives, which was in contrast to taxa that significantly declined under iron plethora. Patients with microbiome-shift were significantly younger and had higher serum phosphate concentrations. In conclusion, this study sheds light on the impact of iron on the microbiome of hemodialysis patients.

Distinct Serum and Fecal Metabolite Profiles Linking With Gut Microbiome in Older Adults With Frailty

Frailty is a critical aging-related syndrome but the underlying metabolic mechanism remains poorly understood. The aim of this study was to identify novel biomarkers and reveal potential mechanisms of frailty based on the integrated analysis of metabolome and gut microbiome. In this study, twenty subjects consisted of five middle-aged adults and fifteen older adults, of which fifteen older subjects were divided into three groups: non-frail, pre-frail, and frail, with five subjects in each group. The presence of frailty, pre-frailty, or non-frailty was established according to the physical frailty phenotype (PFP). We applied non-targeted metabolomics to serum and feces samples and used 16S rDNA gene sequencing to detect the fecal microbiome. The associations between metabolites and gut microbiota were analyzed by the Spearman’s correlation analysis. Serum metabolic shifts in frailty mainly included fatty acids and derivatives, carbohydrates, and monosaccharides. Most of the metabolites belonging to these classes increased in the serum of frail older adults. Propylparaben was found to gradually decrease in non-frail, pre-frail, and frail older adults. Distinct changes in fecal metabolite profiles and gut microbiota were also found among middle-aged adults, non-frail and frail older subjects. The relative abundance of Faecalibacteriu, Roseburia, and Fusicatenibacter decreased while the abundance of Parabacteroides and Bacteroides increased in frailty. The above altered microbes were associated with the changed serum metabolites in frailty, which included dodecanedioic acid, D-ribose, D-(-)-mannitol, creatine and indole, and their related fecal metabolites. The changed microbiome and related metabolites may be used as the biomarkers of frailty and is worthy of further mechanistic studies.

The Nursing Home Older Adult Gut Microbiome Composition Shows Time-dependent Dysbiosis and Is Influenced by Medication Exposures, Age, Environment, and Frailty

Older adults in nursing homes (NHs) have increased frailty, medication, and antimicrobial exposures, all factors that are known to affect the composition of gut microbiota. Our objective was to define which factors have the greatest association with the NH resident gut microbiota, explore patterns of dysbiosis and compositional changes in gut microbiota over time in this environment. We collected serial stool samples from NH residents. Residents were assessed using the Mini Nutritional Assessment tool and Clinical Frailty Scale. Bacterial composition of resident stool samples was determined by metagenomic sequencing. We used mixed-effect random forest modeling to identify clinical covariates that associate with microbiota. We enrolled and followed 166 residents from 5 NHs collecting 512 stool samples and following 15 residents for > 1 year. Medications, particularly psychoactive and antihypertensive medications, had the greatest effect on the microbiota. Age and frailty also contributed, and were associated with increased and decreased diversity, respectively. The microbiota of residents who had lived in the NH for > 1 year were enriched in inflammatory and pathogenic species and reduced in anti-inflammatory and symbiotic species. We observed intraindividual stability of the microbiome among older adults who had lived in the NH already for >1 year followed with sample collections 1 year apart. Older adult NH gut microbiome is heavily influenced by medications, age, and frailty. This microbiome is influenced by the length of NH residency with dysbiosis becoming evident at 12 months, however, after this point there is demonstrated relative stability over time.

Frailty and HIV: Moving from Characterization to Intervention

PURPOSE OF REVIEW

While the characteristics associated with frailty in people with HIV (PWH) have been well described, little is known regarding interventions to slow or reverse frailty. Here we review interventions to prevent or treat frailty in the general population and in people with HIV (PWH).

RECENT FINDINGS

Frailty interventions have primarily relied on nonpharmacologic interventions (e.g., exercise and nutrition). Although few have addressed frailty, many of these therapies have shown benefit on components of frailty including gait speed, strength, and low activity among PWH. When nonpharmacologic interventions are insufficient, pharmacologic interventions may be necessary. Many interventions have been tested in preclinical models, but few have been tested or shown benefit among older adults with or without HIV. Ultimately, pharmacologic and nonpharmacologic interventions have the potential to improve vulnerability that underlies frailty in PWH, though clinical data is currently sparse.

Frailty syndrome: A target for functional nutrients?

Frailty is a late life phenotype characterized by a decline in physiological reserve across several organ systems, resulting in the increased susceptibility to endogenous and/or exogenous stressors. Although the etiology of frailty remains poorly understood, an interconnected network of putative mechanisms linked to the ageing process has been proposed. However, frailty is a dynamic process that may be prevented, delayed, or even reversed. The syndromic nature of frailty requires a multidomain approach, such as proper nutrition, as part of modifiable environmental factors, and represents one of the most promising and least costly ways to prevent and reduce frailty among older adults. Nutrient deficiencies have been consistently associated with frailty; however, mounting evidence also supports the hypothesis that beyond the traditional nutritional value, specific dietary components may exert function-enhancing effects and mitigate the extent of frailty. Thus, further mechanistic studies, along with large clinical trials, are imperative to establish the exact role of functional nutrients in the clinical management of frailty. Here, we provide a contemporary discussion of how emerging functional nutrients may contribute to modify the trajectory of the frailty syndrome.

Gut dysbiosis and age-related neurological diseases; an innovative approach for therapeutic interventions

The gut microbiota is a complex ecosystem of bacteria, fungi, and viruses that acts as a critical regulator in microbial, metabolic, and immune responses in the host organism. Imbalances in the gut microbiota, termed "dysbiosis," often induce aberrant immune responses, which in turn disrupt the local and systemic homeostasis of the host. Emerging evidence has highlighted the importance of gut microbiota in intestinal diseases, and more recently, in age-related central nervous systems diseases, for example, stroke and Alzheimer's disease. It is now generally recognized that gut microbiota significantly influences host behaviors and modulates the interaction between microbiota, gut, and brain, via the "microbiota-gut-brain axis." Several approaches have been utilized to reduce age-related dysbiosis in experimental models and in clinical studies. These include strategies to manipulate the microbiome via fecal microbiota transplantation, administration of prebiotics and probiotics, and dietary interventions. In this review, we explore both clinical and preclinical therapies for treating age-related dysbiosis.