Human gut microbiota and healthy aging: Recent developments and future prospective

The role of the pediatric cutaneous and gut microbiomes in childhood disease: A review

OBJECTIVE

Infancy and early childhood are crucial periods in the development of the human microbiome and shape the trajectory of microbial colonization, immune system development, and systemic disease. We review the development of the skin and gut microbiomes, their connection to the immune system, and their relevance to common pediatric pathologies.

FINDINGS

Beginning after birth, and likely even in utero, colonization of the skin and the gut occur in parallel, influenced by external factors. This colonization, in turn, dictates maturation of the immune system and contributes to conditions from atopic dermatitis to sepsis. Emerging literature is identifying links between the gut and skin microbiomes.

CONCLUSION

The gut and skin microbiomes are associated with pediatric disease states. Immune and microbial plasticity make this unique period an ideal target for intervention. Investigating the purposeful manipulation of the pediatric microbiome may lead to novel treatment and prevention strategies.

Substitution of Sugar-Sweetened Beverages for Other Beverages: Can It Be the Next Step Towards Healthy Aging?

PURPOSE OF REVIEW

With the prolongation of life expectancy, the gap between lifespan and "health span," the disease-free lifespan, has been widening due to the massive burden of age-related chronic diseases and research on healthy aging has been gaining momentum. A growing body of evidence suggests that diet is a strong determinant of healthy aging and consumption of sugar-sweetened beverages (SSB), a major source of added sugars, predicts poor health outcomes in the aging population, including cardiovascular disease, diabetes, and cancer. Evidence further supports a link between sugar-sweetened beverages-triggered pathological processes and biologic factors of aging, including inflammaging, oxidative stress, and alterations in intestinal microbiota. At present, substitution of sugar-sweetened beverages with healthier alternative beverage remains the most robust strategy to limit the deleterious effects of sugar-sweetened beverages on health worldwide and may help achieve healthy longevity. The purpose of this review is to provide an overview of mechanisms by which sugar-sweetened beverages consumption may impact the physiological aging process and how a simple intervention of beverage replacement may promote healthy aging.

RECENT FINDINGS

Recent findings indicate that SSB are associated with accelerated aging phenotype and activate various adverse biological processes such as chronic inflammation, oxidative stress, insulin resistance, and gut dysbiosis. Replacing SSB with healthier beverages may be a reasonable option to reduce the burden of chronic disease in the aging population and even prolong life and healthspan.

Pathobiological Relationship of Excessive Dietary Intake of Choline/L-Carnitine: A TMAO Precursor-Associated Aggravation in Heart Failure in Sarcopenic Patients

The microecological environment of the gastrointestinal tract is altered if there is an imbalance between the gut microbiota phylases, resulting in a variety of diseases. Moreover, progressive age not only slows down physical activity but also reduces the fat metabolism pathway, which may lead to a reduction in the variety of bacterial strains and bacteroidetes' abundance, promoting firmicutes and proteobacteria growth. As a result, dysbiosis reduces physiological adaptability, boosts inflammatory markers, generates ROS, and induces the destruction of free radical macromolecules, leading to sarcopenia in older patients. Research conducted at various levels indicates that the microbiota of the gut is involved in pathogenesis and can be considered as the causative agent of several cardiovascular diseases. Local and systematic inflammatory reactions are caused in patients with heart failure, as ischemia and edema are caused by splanchnic hypoperfusion and enable both bacterial metabolites and bacteria translocation to enter from an intestinal barrier, which is already weakened, to the blood circulation. Multiple diseases, such as HF, include healthy microbe-derived metabolites. These key findings demonstrate that the gut microbiota modulates the host's metabolism, either specifically or indirectly, by generating multiple metabolites. Currently, the real procedures that are an analogy to the symptoms in cardiac pathologies, such as cardiac mass dysfunctions and modifications, are investigated at a minimum level in older patients. Thus, the purpose of this review is to summarize the existing knowledge about a particular diet, including trimethylamine, which usually seems to be effective for the improvement of cardiac and skeletal muscle, such as choline and L-carnitine, which may aggravate the HF process in sarcopenic patients.

The Effect of Dietary Interventions on Chronic Inflammatory Diseases in Relation to the Microbiome: A Systematic Review

Chronic inflammation plays a central role in the pathophysiology of various non-communicable diseases. Dietary interventions can reduce inflammation, in part due to their effect on the gut microbiome. This systematic review aims to determine the effect of dietary interventions, specifically fiber intake, on chronic inflammatory diseases and the microbiome. It aims to form hypotheses on the potential mediating effects of the microbiome on disease outcomes after dietary changes. Included were clinical trials which performed a dietary intervention with a whole diet change or fiber supplement (>5 g/day) and investigated the gut microbiome in patients diagnosed with chronic inflammatory diseases such as cardiovascular disease (CVD), type 2 diabetes (T2DM), and autoimmune diseases (e.g., rheumatoid arthritis (RA), inflammatory bowel disease (IBD)). The 30 articles which met the inclusion criteria had an overall moderate to high risk of bias and were too heterogeneous to perform a meta-analysis. Dietary interventions were stratified based on fiber intake: low fiber, high fiber, and supplemental fiber. Overall, but most pronounced in patients with T2DM, high-fiber plant-based dietary interventions were consistently more effective at reducing disease-specific outcomes and pathogenic bacteria, as well as increasing microbiome alpha diversity and short-chain fatty acid (SCFA)-producing bacteria, compared to other diets and fiber supplements.

Effects of ad libitum free-choice access to freshly squeezed domestic white asparagus juice on intestinal microbiota composition and universal biomarkers of immuno-metabolic homeostasis and general health in middle-aged female and male C57BL/6 mice

BACKGROUND AND PURPOSE

Asparagus contains different bioactive and volatile components including pyrazines, sulphur-containing compounds, and polyphenols. Asparagus juice is a new low-calorie LAB-containing natural juice product, the usage of which is expanding. Pyrazines and sulphur-containing compounds are degraded by bacteria on one hand, but on the other hand, dietary polyphenols prevent human colorectal diseases as modulators of the composition and/or activity of gut microbiota. However, the utility of these asparagus compounds for reversal of age-associated microbial dysbiosis and the immunometabolic disorders that dysbiosis incites body inflammatory reactions was not much explored so far. Hence, using middle-aged mice, we conducted the current study to verify the effect of freshly squeezed domestic white asparagus juice on the biomarkers reflecting immuno-metabolic pathways linking age-related dysbiosis and metabolic events.

MATERIALS AND METHODS

Thirty-two conventional Harlan Laboratories C57BL/6 mice aged between 11-12 months were randomly divided into two groups (n=16). Mice in control group 1 received sterile tap water. Animals in group 2 had 60 days ad libitum free-choice access to sterile tap water supplemented with 5% (v/v) freshly squeezed domestic white asparagus juice. Clinical signs of general health, hydration, and inflammation were monitored daily. Caecal content samples were analysed by qPCR for microbial composition. Histology of relevant organs was carried out on day 60 after sacrificing the mice. Universal markers of metabolic- and liver function were determined in serum samples. Caecal SCFAs contents were measured using HPLC.

RESULTS

Overall, no significant differences in general health or clinical signs of inflammation between the two groups were observed. The liver to body weight ratio in asparagus juice-drank mice was lowered. The qPCR quantification showed that asparagus juice significantly decreased the caecal Clostridium coccoides group while causing an enhancement in Clostridium leptum, Firmicutes, and bifidobacterial groups as well as total caecal bacterial count. Asparagus juice significantly elevated the caecal contents of SCFAs. Enhanced SCFAs (acetate, butyrate, and propionate) in mice receiving asparagus juice, however, did coincide with altered lipid levels in plasma or changes in the abundance of relevant bacteria for acetate-, butyrate-, and propionate production.

DISCUSSION

To the best of our knowledge, this is the first study aiming at evaluating the effect of freshly squeezed German domestic white asparagus juice on universal markers of metabolic- and liver function in middle-aged mice and the role of gut microbiota in this regard. The effectiveness of asparagus juice to improve metabolism in middle-aged mice was associated with alterations in intestinal microbiota but maybe also due to uptake of higher amounts of SCFAs. Hence, the key signal pathways corresponding to improved immune-metabolic homeostasis will be an important research scheme in the future.

Microbiome-Metabolomics Reveals Endogenous Alterations of Energy Metabolism by the Dushen Tang to Attenuate D-Galactose-Induced Memory Impairment in Rats

Aging affects the brain function in elderly individuals, and Dushen Tang (DST) is widely used for the treatment of senile diseases. In this study, the protective effect of DST against memory impairment was evaluated through the Morris water maze (MWM) test and transmission electron microscopy (TEM). A joint analysis was also performed using LC-MS metabolomics and the microbiome. The MWM test showed that DST could significantly improve the spatial memory and learning abilities of rats with memory impairment, and the TEM analysis showed that DST could reduce neuronal damage in the hippocampus of rats with memory impairment. Ten potential biomarkers involving pyruvate metabolism, the synthesis and degradation of ketone bodies, and other metabolic pathways were identified by the metabolomic analysis, and it was found that 3-hydroxybutyric acid and lactic acid were involved in the activation of cAMP signaling pathways. The 16S rDNA sequencing results showed that DST could regulate the structure of the gut microbiota in rats with memory impairment, and these effects were manifested as changes in energy metabolism. These findings suggest that DST exerts a good therapeutic effect on rats with memory impairment and that this effect might be mainly achieved by improving energy metabolism. These findings might lead to the potential development of DST as a drug for the treatment of rats with memory impairment.

SAMP8 Mice as a Model of Age-Related Cognition Decline with Underlying Mechanisms in Alzheimer's Disease

Alzheimer's disease (AD) is a highly age-related cognitive decline frequently attacking the elderly. Senescence-accelerated mouse-prone 8 (SAMP8) is an ideal model to study AD, displaying age-related learning and memory disorders. SAMP8 mice exhibit most features of pathogenesis of AD, including an abnormal expression of anti-aging factors, oxidative stress, inflammation, amyloid-β (Aβ) deposits, tau hyperphosphorylation, endoplasmic reticulum stress, abnormal autophagy activity, and disruption of intestinal flora. SAMP8 mice, therefore, have visualized the understanding of AD, and also provided effective ways to find new therapeutic targets. This review focused on the age-related pathogenesis in SAMP8 mice, to advance the understanding of age-related learning and memory decline and clarify the mechanisms. Furthermore, this review will provide extensive foundations for SAMP8 mice used in therapeutics for AD.

Alzheimer's disease and gut microbiota: does trimethylamine N-oxide (TMAO) play a role?

Alzheimer's disease (AD) is a neurodegenerative disease that affects memory and cognitive function. Clinical evidence has put into question our current understanding of AD development, propelling researchers to look into further avenues. Gut microbiota has emerged as a potential player in AD pathophysiology. Lifestyle factors, such as diet, can have negative effects on the gut microbiota and thus host health. A Western-type diet has been highlighted as a risk factor for both gut microbiota alteration as well as AD development. The gut-derived trimethylamine N-oxide (TMAO) has been previously implied in the development of cardiovascular diseases with recent evidence suggesting a plausible role of TMAO in AD development. Therefore, the main goal of the present review is to provide the reader with potential mechanisms of action through which consumption of a Western-type diet could increase AD risk, by acting through microbiota-produced TMAO. Although a link between TMAO and AD is far from definitive, this review will serve as a call for research into this new area of research.

Bacteroides thetaiotaomicron Ameliorates Experimental Allergic Airway Inflammation via Activation of ICOS+Tregs and Inhibition of Th2 Response

Inhibition of allergic airway diseases (AAD) by immunomodulation of the adaptive immune system through restoration of the enteric dysbiosis is an emerging therapeutic strategy. Patients with allergic rhinitis (n = 6) and healthy controls (n = 6) were enrolled, and gut microbiome composition analysis was performed by 16S rDNA sequencing. We also established an ovalbumin (OVA)-induced allergic airway inflammation murine model. Dysbiosis of the gut flora was observed in both AAD patients and the mice, with the decrease of the biodiversity and the quantity of the Bacteroidetes phylum. Oral application of Bacteroides (B.) thetaiotaomicron ameliorated the symptoms of OVA-induced airway hyperresponsiveness (AHR) and attenuated the airway inflammation in mice. In addition, nasal lavage fluid (NALF) and bronchoalveolar lavage fluid (BALF) from AAD mice orally administered with B. thetaiotaomicron showed reduced numbers of immune cells, and diminished secretion of T helper (Th)-2 cytokines (IL-4, IL-5, and IL-13) compared with the corresponding control mice, whereas the levels of Th1 cytokineIFN-γ was not changed in both the groups. When B. thetaiotaomicron was co-administered with metronidazole in AAD mice, the immunomodulatory effect was weakened and the allergic inflammatory response was aggravated. The ratios of CD4⁺Foxp3⁺ cells, CD4⁺ICOS⁺ T cells, CD4⁺ICOS⁺ Foxp3⁺ regulatory T cells, and IL-10-expressing CD4⁺Foxp3⁺ cells were increased in lymphocytes of spleen, mesenteric, and cervical lymph nodes of AAD mice administrated with B. thetaiotaomicron. Therefore, our data indicate that oral administration of B. thetaiotaomicron effectively inhibited the development of AAD in murine model; inhibition was mediated by the activation of Tregs and inhibition of Th2 response without promoting a Th1 response.

Pre- and postmenopausal women have different core urinary microbiota

Recent studies suggest that alterations in the female urinary microbiota is associated to development of bladder disease. However, the normal microbiota composition and variation in healthy women are poorly described. Moreover, the effects of hormonal changes on microbiota during menopause is not well understood. The aim of our study was to investigate the urinary microbiota in healthy pre- and postmenopausal women without urinary tract symptoms. Microbiota composition in catheterized urine samples was mapped using 16S rRNA gene sequencing. In total, 41 premenopausal and 42 postmenopausal women were initially included. Samples with first PCR amplification concentration below level of the negative control were excluded, resulting in 34 premenopausal and 20 postmenopausal women included in data analysis. Urine from postmenopausal women showed significantly higher alpha diversity compared to premenopausal women. Lactobacillus was the most abundant bacteria in both groups, however the relative abundance of Lactobacillus accounted for 77.8% in premenopausal versus 42.0% in postmenopausal women. In conclusion, urine from premenopausal mostly presented with Lactobacillus dominated urotypes, whereas urine from postmenopausal women presented a more diverse urinary microbiota with higher abundance of the genera Gardnerella and Prevotella. The clinical and pathophysiological implications of this difference remain to be elucidated.

Dietary Pattern, Gut Microbiota, and Alzheimer's Disease

Alzheimer's disease is the most common neurodegenerative disease. Until now, there has been no specific medicine that can cure Alzheimer's disease or effectively reverse the disease process. A good dietary pattern is an efficient way to prevent or delay the progression of the disease. Evidence suggests that diet may affect β-amyloid production and tau processing or may regulate inflammation, metabolism, and oxidative stress associated with Alzheimer's disease, which can be exerted by gut microbiota. The gut microbiota is a complex microbial community that affects not only various digestive diseases but also neurodegenerative diseases. Studies have shown that gut microbial metabolites, such as pro-inflammatory factors, short-chain fatty acids, and neurotransmitters, can affect the pathogenesis of Alzheimer's disease. Clinical studies suggested that the gut microbial composition of patients with Alzheimer's disease is different, in particular to lower abundances of Eubacterium rectale and Bacteroides fragilis, which have an anti-inflammatory activity. The purpose of this review is to summarize the neuropathological pathogenesis of Alzheimer's disease, and the modulation of dietary patterns rather than single dietary components on Alzheimer's disease through the gut-brain axis was discussed.

Profiling the mid-adult cecal microbiota associated with host healthy by using herbal formula Kang ShuaiLao Pian treated mid-adult mice

With the occurrence of aging process, decreased neuron dopamine, disrupted brown adipose tissue (BAT) remodeling and decreased butyrate level all reflect a weak host healthy in certain degree. Nevertheless, the signs of mid-adult gut microbiota, and its association with host healthy are not well understood. In current study, we deemed to illustrate the associations of age, neuron dopamine, BAT remodeling, butyrate and gut microbiota with the aid of traditional herbal formula Kang Shuai Lao Pian (KSLP), which is known for its anti-aging effect. Here, ELISA was performed to detect the production of brain dopamine, the mass of inguinal white adipose tissue versus interscapular brown adipose tissue (iWAT/iBAT) was calculated and considered as a sign of BAT remodeling, 16S rRNA gene sequencing was used to the detection of gut microbiota profiling and gas chromatography was used to measure the butyrate level in mice feces. Our results indicated mid-adult mice already present distinctive gut microbiota profiling compared with young mice, concomitant with which are the lower brain dopamine level and disrupted brown adipose remodeling. KSLP treatment improved the host healthy and regulated gut microbiota with enriched Firmicutes at the expense of Bacteroidetes, particularly increased the relative abundance of bacteria functionally related to dopamine and butyrate productions, which suggest KSLP treatment constructs a healthier gut environment. In conclusion, modulation of gut microbiota and butyrate may connectively regulate dopamine production and BAT remodeling through gut-brain axis and gut-metabolism axis.

Differences in the gut Firmicutes to Bacteroidetes ratio across age groups in healthy Ukrainian population

BACKGROUND

Gut microbiota plays an important role in physiological and pathological processes of the host organism, including aging. Microbiota composition was shown to vary significantly throughout the life course. Age-related changes in the composition of microbiota were reported in several human studies. In present study, age-related dynamics of phylogenetic profile of gut microbiota was investigated in 1550 healthy participants from Ukrainian population.

RESULTS

Significant changes in the microbiota composition determined by qRT-PCR at the level of major microbial phyla across age groups have been observed. The relative abundance of Actinobacteria and Firmicutes phyla increased, while that of Bacteroidetes decreased from childhood to elderly age. Accordingly, the Firmicutes/Bacteroidetes (F/B) ratio was shown to significantly increase until elder age. In both sexes, odds to have F/B > 1 tended to increase with age, reaching maximum values in elder age groups [OR = 2.7 (95% CI, 1.2-6.0) and OR = 3.7 (95% CI, 1.4-9.6) for female and male 60-69-year age groups, respectively, compared to same-sex reference (0-9-year) age groups].

CONCLUSIONS

In conclusion, data from our study indicate that composition of the human intestinal microbiota at the level of major microbial phyla significantly differs across age groups. In both sexes, the F/B ratio tends to increase with age from 0-9-year to 60-69-year age groups. Further studies are needed for a better understanding of mechanisms underlying age-related dynamics of human microbiota composition.

Adolescence and Aging: Impact of Adolescence Inflammatory Stress and Microbiota Alterations on Brain Development, Aging, and Neurodegeneration

Puberty/adolescence is a critical phase during neurodevelopment with numerous structural, neurochemical, and molecular changes occurring in response to genetic and environmental signals. A consequence of this major neuronal reorganizing and remodeling is a heightened level of vulnerability to stressors and immune challenges. The gut microbiota is a fundamental modulator of stress and immune responses and has been found to play a role in mental health conditions and neurodegenerative disorders. Environmental insults (stress, infection, neuroinflammation, and use of antibiotics) during adolescence can result in dysbiosis subsidizing the development of brain disorders later in life. Also, pubertal neuroinflammatory insults can alter neurodevelopment, impact brain functioning in an enduring manner, and contribute to neurological disorders related to brain aging, such as Alzheimer's disease, Parkinson's disease, and depression. Exposure to probiotics during puberty can mitigate inflammation, reverse dysbiosis, and decrease vulnerabilities to brain disorders later in life. The goal of this review is to reveal the consequences of pubertal exposure to stress and immune challenges on the gut microbiota, immune reactivity within the brain, and the risk or resilience to stress-induced mental illnesses and neurodegenerative disorders. We propose that the consumption of probiotics during adolescence contribute to the prevention of brain pathologies in adulthood.

Carbohydrate active enzymes are affected by diet transition from milk to solid food in infant gut microbiota

Infants experience a dramatic change in their food in the first year after birth when they shift from breast milk to solid food. This results in a large change in presence of indigestible polysaccharides, a primary energy resource of gut microbes. How the gut microbiota adapts to this dietary shift has not been well examined. Here, by using metagenomics data, we studied carbohydrate-active enzymes (CAZymes) of gut microbiota, which are essential enzymes catalyzing the breakdown of polysaccharides, during this dietary shift. We developed a new approach to categorize CAZyme families by food intake and found CAZyme families associated with milk or solid food. We also found CAZymes with most abundance in 12 months infants that are not associated with solid food or milk but may be related to modulating carbohydrates in the mucus. Additionally, the abundance of gut CAZymes were found to be affected by many other factors, including delivery modes and life style in adults. Taken together, our findings provide novel insights into the dynamic change of gut CAZymes in early human life and provide potential markers for food interference or gut microbiota restoration.

Age-related analysis of the gut microbiome in a purebred dog colony

Dogs are model animals that can be used to study the gut microbiome. Although the gut microbiome is assumed to be closely related to aging, information pertaining to this relationship in dogs is limited. Here, we examined the association between the canine gut microbiome and age via a bacterial 16S rRNA gene amplicon sequence analysis in a colony of 43 Japanese purebred Shiba Inu dogs. We found that microbial diversity tended to decrease with aging. A differential abundance analysis showed an association of a single specific microbe with aging. The age-related coabundance network analysis showed that two microbial network modules were positively and negatively associated with aging, respectively. These results suggest that the dog gut microbiome is likely to vary with aging.

Unveiling the Role of Inflammation and Oxidative Stress on Age-Related Cardiovascular Diseases

The global population above 60 years has been growing exponentially in the last decades, which is accompanied by an increase in the prevalence of age-related chronic diseases, highlighting cardiovascular diseases (CVDs), such as hypertension, atherosclerosis, and heart failure. Aging is the main risk factor for these diseases. Such susceptibility to disease is explained, at least in part, by the increase of oxidative stress, in which it damages cellular components such as proteins, DNA, and lipids. In addition, the chronic inflammatory process in aging “inflammaging” also contributes to cell damage, creating a stressful environment which drives to the development of CVDs. Taken together, it is possible to identify the molecular connection between oxidative stress and the inflammatory process, especially by the crosstalk between the transcription factors Nrf-2 and NF-κB which are mediated by redox signalling and are involved in aging. Therapies that control this process are key targets in the prevention/combat of age-related CVDs. In this review, we show the basics of inflammation and oxidative stress, including the crosstalk between them, and the implications on age-related CVDs.

Long-term metal exposure changes gut microbiota of residents surrounding a mining and smelting area

In this epidemiologic study, 16 S rRNA sequencing was used to investigate the changes of diversity and composition profile of gut microbiota resulting from long-term exposure to multiple metals, including arsenic (As), cadmium (Cd), cuprum (Cu), lead (Pb), and zinc (Zn). Due to long-term exposure to various metals, the relative abundances of Lachnospiraceae, Eubacterium eligens, Ruminococcaceae UGG-014, Erysipelotrichaceae UCG-003, Tyzzerella 3, Bacteroides, Slackia, italics, and Roseburia were found to become much higher, whereas the abundance of Prevotella 9 presented an opposite trend. Additionally, differences between males and female groups were found, such as the greater richness and evenness of bacteria for men subjected to long-term metal exposure in polluted areas. The changes of men’s microbiomes were more significant as a result of higher daily intake, mining and smelting activity, and living habits. This research presents a new theoretical basis for the correlation between long-term metal exposure and gut health for people living in contaminated areas.

Age-Related Changes in the Gut Microbiota Modify Brain Lipid Composition

Understanding the molecular mechanisms underlying the changes observed during aging is a prerequisite to design strategies to prevent age-related diseases. Aging is associated with metabolic changes, including alteration in the brain lipid metabolism. These alterations may contribute to the development of pathophysiological conditions. Modifications in the gut microbiota composition are also observed during aging. As communication axes exist between the gut microbiota and the brain and knowing that microbiota influences the host metabolism, we speculated on whether age-associated modifications in the gut microbiota could be involved in the lipid changes observed in aging brain. For that purpose, germ-free mice were colonized by the fecal microbiota of young or old donor mice. Lipid classes and fatty acid profiles were determined in the brain (cortex), plasma and liver by thin-layer chromatography on silica gel-coated quartz rods and gas chromatography. Gut colonization by microbiota of old mice resulted in a significant increase in total monounsaturated fatty acids (MUFA) and a significant decrease in the relative amounts of cholesterol and total polyunsaturated fatty acids (PUFA) in the cortex. Among the eight most represented fatty acids in the cortex, the relative abundances of five (C18:1n-9, C22:6n-3, C20:4n-6, C18:1n-7, and C20:1n-9) were significantly altered in mice inoculated with an aged microbiota. Liquid chromatography analyses revealed that the relative abundance of major species among phosphatidyl and plasmenylcholine (PC 16:0/18:1), phosphatidyl and plasmenylethanolamine (PE 18:0/22:6), lysophosphatidylethanolamine (LPE 22:6) and sphingomyelins (SM d18:1/18:0) were significantly altered in the cortex of mice colonized by the microbiota obtained from aged donors. Transplantation of microbiota from old mice also modified the lipid class and fatty acid content in the liver. Finally, we found that the expression of several genes involved in MUFA and PUFA synthesis (Scd1, Fads1, Fads2, Elovl2, and Elovl5) was dysregulated in mice inoculated with an aged microbiota. In conclusion, our data suggest that changes in gut microbiota that are associated with aging can impact brain and liver lipid metabolisms. Lipid changes induced by an aged microbiota recapitulate some features of aging, thus pointing out the potential role of microbiota alterations in the age-related degradation of the health status.

SOD1 deficiency alters gastrointestinal microbiota and metabolites in mice

Redox imbalance induces oxidative damage and causes age-related pathologies. Mice lacking the antioxidant enzyme SOD1 (Sod1^-/-) exhibit various aging-like phenotypes throughout the body and are used as aging model mice. Recent reports suggested that age-related changes in the intestinal environment are involved in various diseases. We investigated cecal microbiota profiles and gastrointestinal metabolites in wild-type (Sod1^+/+) and Sod1^-/- mice. Firmicutes and Bacteroidetes were dominant in Sod1^+/+ mice, and most of the detected bacterial species belong to these two phyla. Meanwhile, the Sod1^-/- mice had an altered Firmicutes and Bacteroidetes ratio compared to Sod1^+/+ mice. Among the identified genera, Paraprevotella, Prevotella, Ruminococcus, and Bacteroides were significantly increased, but Lactobacillus was significantly decreased in Sod1^-/- mice compared to Sod1^+/+ mice. The correlation analyses between cecal microbiota and liver metabolites showed that Bacteroides and Prevotella spp. were grouped into the same cluster, and Paraprevotella and Ruminococcus spp. were also grouped as another cluster. These four genera showed a positive and a negative correlation with increased and decreased liver metabolites in Sod1^-/- mice, respectively. In contrast, Lactobacillus spp. showed a negative correlation with increased liver metabolites and a positive correlation with decreased liver metabolites in Sod1^-/- mice. These results suggest that the redox imbalance induced by Sod1 loss alters gastrointestinal microflora and metabolites.

Gut microbiome of treatment-naïve MS patients of different ethnicities early in disease course

Although the intestinal microbiome has been increasingly implicated in autoimmune diseases, much is unknown about its roles in Multiple Sclerosis (MS). Our aim was to compare the microbiome between treatment-naïve MS subjects early in their disease course and controls, and between Caucasian (CA), Hispanic (HA), and African American (AA) MS subjects. From fecal samples, we performed 16S rRNA V4 sequencing and analysis from 45 MS subjects (15 CA, 16 HA, 14 AA) and 44 matched healthy controls, and whole metagenomic shotgun sequencing from 24 MS subjects (all newly diagnosed, treatment-naïve, and steroid-free) and 24 controls. In all three ethnic groups, there was an increased relative abundance of the same single genus, Clostridium, compared to ethnicity-matched controls. Analysis of microbiota networks showed significant changes in the network characteristics between combined MS cohorts and controls, suggesting global differences not restricted to individual taxa. Metagenomic analysis revealed significant enrichment of individual species within Clostridia as well as particular functional pathways in the MS subjects. The increased relative abundance of Clostridia in all three early MS cohorts compared to controls provides candidate taxa for further study as biomarkers or as etiologic agents in MS.

The lung microbiome: clinical and therapeutic implications

The human respiratory tract, usually considered sterile, is currently being investigated for human-associated microbial communities. According to Dickson's conceptual model, the lung microbiota (LMt) is a dynamic ecosystem, whose composition, in healthy lungs, is likely to reflect microbial migration, reproduction, and elimination. However, which microbial genera constitutes a "healthy microbiome" per se remains hotly debated. It is now widely accepted that a bi-directional gut-lung axis connects the intestinal with the pulmonary microbiota and that the diet could have a role in modulating both microbiotas as in health as in pathological status. The LMt is altered in numerous respiratory disorders such as obstructive airway diseases, interstitial lung diseases, infections, and lung cancer. Some authors hypothesize that the use of specific bacterial strains, termed "probiotics," with positive effects on the host immunity and/or against pathogens, could have beneficial effects in the treatment of intestinal disorders and pulmonary diseases. In this manuscript, we have reviewed the literature available on the LMt to delineate and discuss the potential relationship between composition alterations of LMt and lung diseases. Finally, we have reported some meaningful clinical studies that used integrated probiotics' treatments to contrast some lung-correlated disorders.

Gastro-intestinal and oral microbiome signatures associated with healthy aging

The human oral and gut microbiomes influence health via competition for a distinct niche in the body with pathogens, via metabolic capabilities that increase host digestive capacity and generate compounds engaged in signaling pathways and modulation of immune system functions. Old age alters our metabolic and regenerative capacity. Following recruitment of 65 human subjects in the age range of 70 to 82, we discerned healthy aging (HA) and non-healthy aging (NHA) cohorts discordant in the occurrence of one or more major diseases: (1) cancer, (2) acute or chronic cardiovascular diseases, (3) acute or chronic pulmonary diseases, (4) diabetes, and (5) stroke or neurodegenerative disorders. We analyzed these cohorts' oral microbiomes (saliva) and gut microbiomes (stool) to assess diversity and identify microbial biomarkers for HA. In contrast to the gut microbiome where no change was observed, we found that the saliva microbiome had higher α-diversity in the HA compared with the NHA group. We observed the genus Akkermansia to be significantly more abundant in the gut microbiota of the HA group. Akkermansia muciniphila is a colonic mucin-degrading bacterium believed to have beneficial effects on gastrointestinal health, particularly in the context of diabetes and obesity. Erysipelotrichaceae UCG-003 was a taxon increased in abundance in the HA cohort. Streptococcus was the only genus observed to be significantly decreased in abundance in both the gut and oral microbiomes of the HA cohort compared with the NHA cohort. Our data support the notion that these microbes are potential probiotics to decrease the risks of non-healthy aging.

The effects of plant-based diets on the body and the brain: a systematic review

Western societies notice an increasing interest in plant-based eating patterns such as vegetarian and vegan, yet potential effects on the body and brain are a matter of debate. Therefore, we systematically reviewed existing human interventional studies on putative effects of a plant-based diet on the metabolism and cognition, and what is known about the underlying mechanisms. Using the search terms "plant-based OR vegan OR vegetarian AND diet AND intervention" in PubMed filtered for clinical trials in humans retrieved 205 studies out of which 27, plus an additional search extending the selection to another five studies, were eligible for inclusion based on three independent ratings. We found robust evidence for short- to moderate-term beneficial effects of plant-based diets versus conventional diets (duration ≤ 24 months) on weight status, energy metabolism and systemic inflammation in healthy participants, obese and type-2 diabetes patients. Initial experimental studies proposed novel microbiome-related pathways, by which plant-based diets modulate the gut microbiome towards a favorable diversity of bacteria species, yet a functional "bottom up" signaling of plant-based diet-induced microbial changes remains highly speculative. In addition, little is known, based on interventional studies about cognitive effects linked to plant-based diets. Thus, a causal impact of plant-based diets on cognitive functions, mental and neurological health and respective underlying mechanisms has yet to be demonstrated. In sum, the increasing interest for plant-based diets raises the opportunity for developing novel preventive and therapeutic strategies against obesity, eating disorders and related comorbidities. Still, putative effects of plant-based diets on brain health and cognitive functions as well as the underlying mechanisms remain largely unexplored and new studies need to address these questions.

Integrative analysis of gut microbiota composition, host colonic gene expression and intraluminal metabolites in aging C57BL/6J mice

The aging process is associated with diminished colonic health. In this study, we applied an integrative approach to reveal potential interactions between determinants of colonic health in aging C57BL/6J mice. Analysis of gut microbiota composition revealed an enrichment of various potential pathobionts, including Desulfovibrio spp., and a decline of the health-promoting Akkermansia spp. and Lactobacillus spp. during aging. Intraluminal concentrations of various metabolites varied between ages and we found evidence for an increased gut permeability at higher age. Colonic gene expression analysis suggested that during the early phase of aging (between 6 and 12 months), expression of genes involved in epithelial-to-mesenchymal transition and (re)organization of the extracellular matrix were increased. Differential expression of these genes was strongly correlated with Bifidobacterium spp. During the later phase of aging (between 12 and 28 months), gene expression profiles pointed towards a diminished antimicrobial defense and were correlated with an uncultured Gastranaerophilales spp. This study demonstrates that aging is associated with pronounced changes in gut microbiota composition and colonic gene expression. Furthermore, the strong correlations between specific bacterial genera and host gene expression may imply that orchestrated interactions take place in the vicinity of the colonic wall and potentially mediate colonic health during aging.

Role of the Microbiota in the Modulation of Vaccine Immune Responses

The human immune system and the microbiota co-evolve, and their balanced relationship is based on crosstalk between the two systems through the course of life. This tight association and the overall composition and richness of the microbiota play an important role in the modulation of host immunity and may impact the immune response to vaccination. The availability of innovative technologies, such as next-generation sequencing (NGS) and correlated bioinformatics tools, allows a deeper investigation of the crosstalk between the microbiota and human immune responses. This review discusses the current knowledge on the influence of the microbiota on the immune response to vaccination and novel tools to deeply analyze the impact of the microbiome on vaccine responses.

Gut Microbial Compositions in Four Age Groups of Tibetan Minipigs

In this study, the gut microbiota was characterized in four age strata of Tibetan minipigs. Results indicated that the fecal bacteria of 7-, 28-, 56-, and 180-day-old minipigs did not significantly differ in terms of phylogenetic diversity (i.e., PD whole tree) or the Shannon index (both, p > 0.05). Findings of a principal coordinate analysis demonstrated that fecal bacteria of 180-day-old minipigs were discernable from those of the other three age groups. From ages seven to 56 days, the abundance of Bacteroidetes or Firmicutes appeared to vary. Regarding genera, the populations of Bacteroides and Akkermansia decreased with increasing age.

Lactobacillus sp. improved microbiota and metabolite profiles of aging rats

Aging is closely associated with altered gut function and composition, in which elderly were reported with reduced gut microbiota diversity and increased incidence of age-related diseases. Probiotics have been shown to exert beneficial health-promoting effects through modulation of intestinal microflora biodiversity, thus the effects of probiotics administration on D-galactose (D-gal) senescence-induced rat were evaluated based on the changes in gut microbiota and metabolomic profiles. Upon senescence induction, the ratio of Firmicutes/ Bacteroidetes was significantly lowered, while treatment with Lactobacillus helveticus OFS 1515 and L. fermentum DR9 increased the ratio at the phylum level (P < 0.05). Study on the genus level showed that L. paracasei OFS 0291 and L. helveticus OFS 1515 administration reduced Bacteroides, which are prominently opportunistic pathogens while L. fermentum DR9 treated rats promoted the proliferation of Lactobacillus compared to the aged rats (P < 0.05). Probiotics treatment did not alter fecal short-chain fatty acid (SCFA) profile, but an increase in acetate was observed in the D-gal rats. The analysis of fecal water-soluble metabolites showed that D-gal induced senescence caused great impact on amino acids metabolism such as urocanic acid, citrulline, cystamine and 5-oxoproline, which could serve as potential aging biomarkers. Treatment with probiotics ameliorated these metabolites in a strain-specific manner, whereby L. fermentum DR9 promoted antioxidative effect through upregulation of oxoproline, whereas both L. paracasei OFS 0291 and L. helveticus OFS 1515 restored the levels of reducing sugars, arabinose and ribose similar to the young rats. D-gal induced senescence did cause significant immunological alteration in the colon of aged rats however, all probiotic strains demonstrated immunomodulatory properties as L. paracasei OFS 0291, L. helveticus OFS 1515 and L. fermentum DR9 alleviated proinflammatory cytokines TNF-α, IFN-γ and IL-1β as well as IL-4 compared to the aged control (P < 0.05). Our study highlights the potential of probiotics as an anti-aging therapy through healthy gut modulation.

In vitro neuroprotective activities of two distinct probiotic consortia

Neurodegeneration has been linked to changes in the gut microbiota and this study compares the neuroprotective capability of two bacterial consortia, known as Lab4 and Lab4b, using the established SH-SY5Y neuronal cell model. Firstly, varying total antioxidant capacities (TAC) were identified in the intact cells from each consortia and their secreted metabolites, referred to as conditioned media (CM). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Crystal Violet (CV) assays of cell viability revealed that Lab4 CM and Lab4b CM could induce similar levels of proliferation in SH-SY5Y cells and, despite divergent TAC, possessed a comparable ability to protect undifferentiated and retinoic acid-differentiated cells from the cytotoxic actions of rotenone and undifferentiated cells from the cytotoxic actions of 1-methyl-4-phenylpyridinium iodide (MPP+). Lab4 CM and Lab4b CM also had the ability to attenuate rotenone-induced apoptosis and necrosis with Lab4b inducing the greater effect. Both consortia showed an analogous ability to attenuate intracellular reactive oxygen species accumulation in SH-SY5Y cells although the differential upregulation of genes encoding glutathione reductase and superoxide dismutase by Lab4 CM and Lab4b CM, respectively, implicates the involvement of consortia-specific antioxidative mechanisms of action. This study implicates Lab4 and Lab4b as potential neuroprotective agents and justifies their inclusion in further in vivo studies.

Weight loss probiotic supplementation effect in overweight and obesity subjects: A review

Obese individuals present adverse changes in the diversity and composition of the gut microbiota, leading to alterations in energy balance, lipid metabolism, endocrine disturbances, and low-grade chronic systemic inflammation increases. Probiotic supplementation appears to change gut microbiota by decrease gut permeability, inflammation, and metabolic disorders, creating a promising environment to weight loss. This revision resumes the main findings of probiotic supplementation and weight loss that contributed to building the current background linking changes in gut microbiota profile and with obesity.

Gut microbiota profile in healthy Indonesians

BACKGROUND

Recently, gut microbiota has been associated with various diseases other than intestinal disease. Thus, there has been rapid growth in the study of gut microbiota. Considering the numerous factors influencing gut microbiota such as age, diet, etc., area-based research is required. Indonesia has numerous different tribes and each of these tribes have different lifestyles. Hence, it is expected that each tribe has a specific gut microbiota. A deeper insight into the composition of gut microbiota can be used to determine the condition of gut microbiota in Indonesians and to consider which treatment may be suitable and effective to improve health status.

AIM

To investigate the gut microbiota of Indonesian subjects represented by Javanese and Balinese tribes by analyzing fecal samples.

METHODS

Fecal samples were collected from a total of 80 individuals with 20 in each of the young groups ranging from 25-45 years and the elderly group aged 70 years or more from two different regions, Yogyakarta and Bali. Fecal sample collection was performed at the end of the assessment period (day 14 ± 1 d) during which time the subjects were not allowed to consume probiotic or antibiotic products. The quantification of various Clostridium subgroups, Lactobacillus subgroups, Enterococcus, Streptococcus, Staphylococcus, Bacteroides fragilis group and Prevotella, Bifidobacterium and Atopobium cluster, Enterobacteriaceae and Pseudomonas was performed using the Yakult intestinal flora-scan (YIF-SCAN).

RESULTS

The bacterial population in younger subjects’ feces was higher than that in the elderly population, with a total of approximately 10.0 – 10.6 log₁₀ bacterial cells/g feces. The most abundant bacteria in all groups were Clostridium, followed by Prevotella, Atopobium, Bifidobacterium and Bacteroides. In the elderly, an increase in Enterobacteriaceae, Coliform and Escherichia coli was found. In terms of bacterial counts in Yogyakarta, total bacteria, Clostridium coccoides (C. coccoides) group, Bifidobacterium, Prevotella, Lactobacillus plantarum subgroup, and Streptococcus were significantly higher (P < 0.05) in younger than elderly subjects, while the Lactobacillus gasseri subgroup, Lactobacillus casei subgroup, and Lactobacillus reuteri subgroup counts were significantly lower (P < 0.05) in younger subjects. In Balinese subjects, total bacteria, C. coccoides group, Clostridium leptum subgroup, Bacteroides fragilis group, and Prevotella were significantly higher (P < 0.05) in younger compared to elderly individuals, while the Lactobacillus ruminis subgroup, and Enterobacteriaceae were significantly lower (P < 0.05) in younger subjects. The results also revealed that, besides the C. coccoides group and Clostridium leptum group being the most abundant gut microbiota in both Yogyakarta and Balinese people, the latter was indicated by a higher Clostridium perfringens count, which was almost 10 times that of Yogyakarta subjects. This may be a response to different lifestyles in the different tribes; however, this phenomenon requires further extensive study.

CONCLUSION

Bacterial populations were higher in younger than in elderly subjects. Most abundant bacterial groups were Clostridium, Prevotella, Atopobium, Bifidobacterium, and Bacteroides. The level of Clostridium perfringens in Yogyakarta subjects was lower than that in Balinese subjects.

Dysbiosis of the Gut Microbiota on the Inflammatory Background due to Lack of Suppressor of Cytokine Signalling-1 in Mice

Background

Both environmental and genetic factors have been implicated in the induction of autoimmune disease. Therefore, it is important to understand the pathophysiological significance of the gut microbiota and host genetic background that contribute to an autoimmune disease such as inflammatory bowel disease (IBD). We have previously reported that mice deficient for suppressor of cytokine signaling-1 (SOCS1), in which SOCS1 expression was restored in T and B cells on an SOCS1^-/- background (SOCS1^-/-Tg mice), developed systemic autoimmune diseases accompanied by spontaneous colitis.

Methods

To investigate whether the proinflammatory genetic background affects the gut microbiota, we used SOCS1^-/-Tg mice as a model of spontaneous chronic colitis. Fecal samples were collected from SOCS1^-/-Tg mice and SOCS1^+/+Tg (control) mice at 1 and 6 months of age, and the fecal bacterial 16S ribosomal RNA genes were sequenced using the Illumina MiSeq platform.

Results

Gut microbial diversity was significantly reduced and the intestinal bacterial community composition changed in SOCS1^-/-Tg mice in comparison with the control mice. Interestingly, the population of Prevotella species, which is known to be elevated in ulcerative colitis and colorectal cancer patients, was significantly increased in SOCS1^-/-Tg mice regardless of age.

Conclusion

Taken together, these results suggest that the proinflammatory genetic background owing to SOCS1 deficiency causes dysbiosis of the gut microbiota, which in turn generates a procolitogenic environment.

Gut microbiota and Hashimoto's thyroiditis

About two third of the human microbial commensal community, namely the gut microbiota, is hosted by the gastrointestinal tract which represents the largest interface of the organism to the external environment. This microbial community co-evolved in a symbiotic relationship with the human beings. Growing evidence support the notion that the microbiota plays a significant role in maintaining nutritional, metabolic and immunologic homeostasis in the host. Microbiota, beside the expected role in maintaining gastrointestinal homeostasis also exerts metabolic functions in nutrients digestion and absorption, detoxification and vitamins' synthesis. Intestinal microbiota is also key in the correct development of the lymphoid system, 70% of which resides at the intestinal level. Available studies, both in murine models and humans, have shown an altered ratio between the different phyla, which characterize a" normal" gut microbiota, in a number of different disorders including obesity, to which a significant part of the studies on intestinal microbiota has been addressed so far. These variations in gut microbiota composition, known as dysbiosis, has been also described in patients bearing intestinal autoimmune diseases as well as type 1 diabetes mellitus, systemic sclerosis and systemic lupus erythematosus. Being Hashimoto's thyroiditis the most frequent autoimmune disorder worldwide, the analysis of the reciprocal influence with intestinal microbiota gained interest. The whole thyroid peripheral homeostasis may be sensitive to microbiota changes but there is also evidence that the genesis and progression of autoimmune thyroid disorders may be significantly affected from a changing intestinal microbial composition or even from overt dysbiosis. In this brief review, we focused on the main features which characterize the reciprocal influence between microbiota and thyroid autoimmunity described in the most recent literature.

Pro-resolving lipid mediators: Agents of anti-ageing?

Inflammation is an essential response to injury and its timely and adequate resolution permits tissue repair and avoidance of chronic inflammation. Ageing is associated with increased inflammation, sub-optimal resolution and these act as drivers for a number of ageing-associated pathologies. We describe the role played by specialised proresolving lipid mediators (SPMs) in the resolution of inflammation and how insufficient levels of these mediators, or compromised responsiveness may play a role in the pathogenesis of many ageing-associated pathologies, e.g. Alzheimer's Disease, atherosclerosis, obesity, diabetes and kidney disease. Detailed examination of the resolution phase of inflammation highlights the potential to harness these lipid mediators and or mimetics of their bioactions, in particular, their synthetic analogues to promote effective resolution of inflammation, without compromising the host immune system.

Diabetic gut microbiota dysbiosis as an inflammaging and immunosenescence condition that fosters progression of retinopathy and nephropathy

The increased prevalence of type 2 diabetes mellitus (T2DM) and life expectancy of diabetic patients fosters the worldwide prevalence of retinopathy and nephropathy, two major microvascular complications that have been difficult to treat with contemporary glucose-lowering medications. The gut microbiota (GM) has become a lively field research in the last years; there is a growing recognition that altered intestinal microbiota composition and function can directly impact the phenomenon of ageing and age-related disorders. In fact, human GM, envisaged as a potential source of novel therapeutics, strongly modulates host immunity and metabolism. It is now clear that gut dysbiosis and their products (e.g. p-cresyl sulfate, trimethylamine‑N‑oxide) dictate a secretory associated senescence phenotype and chronic low-grade inflammation, features shared in the physiological process of ageing ("inflammaging") as well as in T2DM ("metaflammation") and in its microvascular complications. This review provides an in-depth look on the crosstalk between GM, host immunity and metabolism. Further, it characterizes human GM signatures of elderly and T2DM patients. Finally, a comprehensive scrutiny of recent molecular findings (e.g. epigenetic changes) underlying causal relationships between GM dysbiosis and diabetic retinopathy/nephropathy complications is pinpointed, with the ultimate goal to unravel potential pathophysiological mechanisms that may be explored, in a near future, as personalized disease-modifying therapeutic approaches.

Diet, Microbiota and Gut-Lung Connection

The gut microbial community (Gut microbiota) is known to impact metabolic functions as well as immune responses in our body. Diet plays an important role in determining the composition of the gut microbiota. Gut microbes help in assimilating dietary nutrients which are indigestible by humans. The metabolites produced by them not only modulate gastro-intestinal immunity, but also impact distal organs like lung and brain. Micro-aspiration of gut bacteria or movement of sensitized immune cells through lymph or bloodstream can also influence immune response of other organs. Dysbiosis in gut microbiota has been implicated in several lung diseases, including allergy, asthma and cystic fibrosis. The bi-directional cross-talk between gut and lung (termed as Gut-Lung axis) is best exemplified by intestinal disturbances observed in lung diseases. Some of the existing probiotics show beneficial effects on lung health. A deeper understanding of the gut microbiome which comprises of all the genetic material within the gut microbiota and its role in respiratory disorders is likely to help in designing appropriate probiotic cocktails for therapeutic applications.

Identification of gut microbiome signatures associated with longevity provides a promising modulation target for healthy aging

The world population is aging, which poses a significant burden to the economy and health care system. As people age, so do their gut microbiomes. Age-related changes in gut microbiome have been reported, including decreased microbial diversity and increased Proteobacteria. Recently, we characterized the gut microbiome of a group of long-living (≥ 90 years old) Chinese people. Interestingly, the diversity of their gut microbiome was greater than that of a young adult control group. We also identified several potentially beneficial bacteria enriched in the long-living Chinese group. These results were validated using data from an independent Italian cohort that included a group of long-living individuals. Other recent studies have found similar results. Here, we provide a summary of these discoveries and discuss their implications in healthy aging.

HIV and aging: role of the microbiome

PURPOSE OF REVIEW

The purpose of this article is to review age-associated alterations in microbiota composition, diversity and functional features in context of immune senescence, chronic inflammation and comorbidities associated with HIV infection. The overall goal is to assess whether modulating the microbiome will likely improve resilience of the immune system and augment return to health.

RECENT FINDINGS

Alteration in the gut microbiota composition diversity and function occur in HIV and aging. Importantly, butyrate producing bacteria are reduced in both HIV and aging individuals. There is increasing relevance of studying metabolomics in the context of HIV-associated non-AIDS comorbidities and aging. Interventional prospects of probiotics, prebiotics and fecal microbiota transplantation in HIV and aging will provide novel therapeutic approaches.

SUMMARY

Increasing evidence suggests a significant link in changes in the composition, diversity and functional aspects of intestinal microbiome with normal aging and HIV infection. Data on association of metabolites produced by the microbiome with HIV-associated non-AIDS comorbidities is mounting. The impact of the microbiome alterations on inflammation, immune and organ senescence and mechanisms by which bio-behavioral pathways will exacerbate these outcomes needs to be further evaluated.

The Fecal Microbiota in the Domestic Cat (Felis catus) Is Influenced by Interactions Between Age and Diet; A Five Year Longitudinal Study

In humans, aging is associated with changes in the gastrointestinal microbiota; these changes may contribute to the age-related increase in incidence of many chronic diseases, including Type 2 diabetes. The life expectancies of cats are increasing, and they are also exhibiting the same types of diseases. While there are some studies investigating the impacts of diets on gastrointestinal microbiota in young cats, the impacts of aging in older cats has not been explored. We followed a cohort of related kittens, maintained on two commercial diets (kibbled and canned) from weaning (8 weeks) to 5 years of age (260 weeks). We hypothesized that the long-term feeding of specific diet formats would (a) lead to microbial composition changes due to aging, (b) impact body composition, and (c) affect insulin sensitivity in the aging cat. We observed that both diet and age affected fecal microbial composition, and while age correlated with changes in body composition, diet had no effect on body composition. Similarly insulin sensitivity was not affected by age nor diet. 16S rRNA sequencing found unclassified Peptostreptococcaceae were prominent across all ages averaging 21.3% of gene sequence reads and were higher in cats fed canned diets (average of 25.7% of gene sequence reads, vs. 17.0% for kibble-fed cats). Age-related effects on body composition and insulin sensitivity may become apparent as the cats grow older; this study will continue to assess these parameters.

Age, menopausal status and the bladder microbiome

OBJECTIVES

The bladder is not sterile but contains a healthy community of microbes termed the microbiome. Alterations in the bladder microbiome have been demonstrated in disease states such as the overactive bladder. The microbiome in other anatomical niches is known to alter with age eg the vagina. The objective of this study was to identify if the bladder microbiome in healthy women varies with age and menopausal status.

STUDY DESIGN

Urine from 79 healthy women attending secondary care gynaecological clinics with no urinary symptoms provided clean catch mid-stream urine specimens. Urine was centrifuged and the resultant pellet was re-suspended and inoculated onto chocolate agar plates and cultured under either aerobic or anaerobic conditions. Morphologically different colonies were purity plated and 16 s rRNA gene sequencing was performed. A microbe genomic basic local alignment search tool (BLAST) was used to identify the genus of the bacteria.

RESULTS

There was no significant correlation between the age of a woman and the number of different genera identified (r=-0.034, p = 0.79). There were few significant differences in the frequency with which the majority of organisms were found in pre and post-menopausal women. The exceptions however were lactobacillus, which was more common in pre-menopausal women (31 vs 3 p = 0.002) and Mobiluncus, which was more common in post-menopausal women (0 vs 3 p = 0.02).

CONCLUSIONS

There was no significant correlation between patient age and diversity of the bladder microbiome but large numbers of different organisms were identified. Significant differences were however observed for Lactobacillus which is more common in pre-menopausal women and Mobiluncus which is more common in post-menopausal women.

Healthy ageing: the natural consequences of good nutrition-a conference report

Many countries are witnessing a marked increase in longevity and with this increased lifespan and the desire for healthy ageing, many, however, suffer from the opposite including mental and physical deterioration, lost productivity and quality of life, and increased medical costs. While adequate nutrition is fundamental for good health, it remains unclear what impact various dietary interventions may have on prolonging good quality of life. Studies which span age, geography and income all suggest that access to quality foods, host immunity and response to inflammation/infections, impaired senses (i.e., sight, taste, smell) or mobility are all factors which can limit intake or increase the body's need for specific micronutrients. New clinical studies of healthy ageing are needed and quantitative biomarkers are an essential component, particularly tools which can measure improvements in physiological integrity throughout life, thought to be a primary contributor to a long and productive life (a healthy "lifespan"). A framework for progress has recently been proposed in a WHO report which takes a broad, person-centered focus on healthy ageing, emphasizing the need to better understand an individual's intrinsic capacity, their functional abilities at various life stages, and the impact by mental, and physical health, and the environments they inhabit.

Synthetic Biology and the Gut Microbiome

The gut microbiome plays a crucial role in maintaining human health. Functions performed by gastrointestinal microbes range from regulating metabolism to modulating immune and nervous system development. Scientists have attempted to exploit this importance through the development of engineered probiotics that are capable of producing and delivering small molecule therapeutics within the gut. However, existing synthetic probiotics are simplistic and fail to replicate the complexity and adaptability of native homeostatic mechanisms. In this review, the ways in which the tools and approaches of synthetic biology have been applied to improve the efficacy of therapeutic probiotics, and the ways in which they might be applied in the future is discussed. Simple devices, such as a bistable switches and integrase memory arrays, have been successfully implemented in the mammalian gut, and models for targeted delivery in this environment have also been developed. In the future, it will be necessary to introduce concepts such as logic-gating and biocontainment mechanisms into synthetic probiotics, as well as to expand the collection of relevant biosensors. Ideally, this will bring us closer to a reality in which engineered therapeutic microbes will be able to accurately diagnose and effectively respond to a variety of disease states.

Leukocyte count, systemic inflammation, and health status in older adults: a narrative review

Epidemiological and clinical studies suggest that elevated leukocyte count within the normal range can predict cardiovascular and total mortality in older adults. These findings are remarkable because this simple and common laboratory test is included in routine medical check-ups. It is well known that chronic systemic inflammation (inflammaging) is one of the hallmarks of aging and an important component of obesity-associated insulin resistance that can lead to type 2 diabetes and other health problems in both overweight individuals and elderly people. To understand the molecular mechanisms linking increased systemic inflammation with aging-associated diseases and elevated leukocyte counts in the elderly is to unravel the multiplicity of molecular factors and mechanisms involved in chronic low-grade systemic inflammation, the gradual accumulation of random molecular damage, age-related diseases, and the process of leukopoiesis. There are several possible mechanisms through which chronic low-grade systemic inflammation is associated with both higher leukocyte count and a greater risk of aging-associated conditions in older adults. For example, the IL-6 centric model predicts that this biomediator is involved in chronic systemic inflammation and leukopoiesis, thereby suggesting that elevated leukocyte count is a signal of poor health in older adults. Alternatively, an increase in neutrophil and monocyte counts can be a direct cause of cardiovascular events in the elderly. Interestingly, some authors assert that the predictive ability of elevated leukocyte counts with regard to cardiovascular and allcause mortality among older adults surpass the predictive value of total cholesterol. This review reports the recent findings on the links between elevated but normal leukocyte counts and the increased risks of all-cause, cardiovascular, and cancer mortality. The possible molecular mechanisms linking higher but normal leukocyte counts with increased risk of aging-associated diseases in the elderly are discussed here.

Gut flora-dependent metabolite Trimethylamine-N-oxide accelerates endothelial cell senescence and vascular aging through oxidative stress

Trimethylamine-N-oxide (TMAO), gut microbiota-dependent metabolites, has been shown to be associated with cardiovascular diseases. However, little is known about the relationship between TMAO and vascular aging. Here, we observed a change in TMAO during the aging process and the effects of TMAO on vascular aging and endothelial cell (EC) senescence. We analyzed age-related plasma levels of TMAO in young adults (18-44 years old), older adults (≥ 65 years old), and 1-month-old, 3-month-old, 6-month-old and 10-month-old senescence-accelerated mouse prone 8 (SAMP8) and age-matched senescence-accelerated mouse resistance 1 (SAMR1) models. We found that circulating TMAO increased with age both in humans and mice. Next, we observed that a TMAO treatment for 16 weeks induced vascular aging in SAMR1 mice and accelerated the process in SAMP8 mice, as measured by an upregulation of senescence markers including senescence-associated β-galactosidase (SA-β-gal), p53, and p21, vascular dysfunction and remodeling. In vitro, we demonstrated that prolonged TMAO treatment induced senescence in human umbilical vein endothelial cells (HUVECs), characterized by reduced cell proliferation, increased expressions of senescence markers, stagnate G0/G1, and impaired cell migration. Furthermore, TMAO suppressed sirtuin 1 (SIRT1) expression and increased oxidative stress both in vivo and in vitro and then activated the p53/p21/Rb pathway resulting in increased p53, acetylation of p53, p21, and decreased CDK2, cyclinE1, and phosphorylation of Rb. In summary, these data suggest that elevated circulating TMAO during the aging process may deteriorate EC senescence and vascular aging, which is probably associated with repression of SIRT1 expression and increased oxidative stress, and, thus, the activation of the p53/p21/Rb pathway.