Lifelong calorie restriction affects indicators of colonic health in aging C57Bl/6J mice

Impact of a Whole-Food, High-Soluble Fiber Diet on the Gut-Muscle Axis in Aged Mice

Previous studies have identified a role for the gut microbiome and its metabolic products, short-chain fatty acids (SCFAs), in the maintenance of muscle mass and physical function (i.e., the gut-muscle axis), but interventions aimed at positively impacting the gut-muscle axis during aging are sparse. Gut bacteria ferment soluble fiber into SCFAs, and accordingly, to evaluate the impact of a high-soluble-fiber diet (HSFD) on the gut-muscle axis, we fed a whole-food, 3×-higher-soluble fiber-containing diet (relative to standard chow) to aged (98 weeks) C57BL/6J mice for 10 weeks. The HSFD significantly altered gut bacterial community structure and composition, but plasma SCFAs were not different, and a positive impact on muscle-related measures (when normalized to body weight) was not identified. However, when evaluating sex differences between dietary groups, female (but not male) HSFD-fed mice had significant increases for SCFAs, the quadriceps/body weight (BW) ratio, and treadmill work performance (distance run × BW), which suggests that an HSFD can positively impact the gut-muscle axis. In contrast, consistent effects in both male and female HSFD-fed mice included weight and fat loss, which suggests a positive role for an HSFD on the gut-adipose axis in aged mice.

The influence of the gut microbiome on ovarian aging

Ovarian aging occurs prior to the aging of other organ systems and acts as the pacemaker of the aging process of multiple organs. As life expectancy has increased, preventing ovarian aging has become an essential goal for promoting extended reproductive function and improving bone and genitourinary conditions related to ovarian aging in women. An improved understanding of ovarian aging may ultimately provide tools for the prediction and mitigation of this process. Recent studies have suggested a connection between ovarian aging and the gut microbiota, and alterations in the composition and functional profile of the gut microbiota have profound consequences on ovarian function. The interaction between the gut microbiota and the ovaries is bidirectional. In this review, we examine current knowledge on ovary-gut microbiota crosstalk and further discuss the potential role of gut microbiota in anti-aging interventions. Microbiota-based manipulation is an appealing approach that may offer new therapeutic strategies to delay or reverse ovarian aging.

Dietary restriction rescues 5-fluorouracil-induced lethal intestinal toxicity in old mice by blocking translocation of opportunistic pathogens

Chemotherapy remains a major treatment for malignant tumors, yet the application of standard dose intensity chemotherapy is limited due to the side effects of cytotoxic drugs, especially in old populations. The underlying mechanisms of cytotoxicity and strategies to increase the safety and tolerance of chemotherapy remain to be explored. Using 5-fluorouracil (5-FU), a cornerstone chemotherapeutic drug, we demonstrate that the main cause of death in ad libitum (AL) fed mice after 5-FU chemotherapy was infection caused by translocation of intestinal opportunistic pathogens. We show that these opportunistic pathogens greatly increase in the intestine after chemotherapy, which was closely related to loss of intestinal lysozyme. Of note, two weeks of dietary restriction (DR) prior to chemotherapy significantly protected the loss of lysozyme and increased the content of the beneficial Lactobacillus genera, resulting in a substantial inhibition of intestinal opportunistic pathogens and their translocation. The rescue effect of DR could be mimicked by Lysozyme or Lactobacillus gavage. Our study provides the first evidence that DR achieved a comprehensive protection of the intestinal physical, biological and chemical barriers, which significantly improved the overall survival of 5-FU-treated mice. Importantly, the above findings were more prominent in old mice. Furthermore, we show that patients over 65 years old have enriched opportunistic pathogens in their gut microbiota, especially after 5-FU based chemotherapy. Our study reveals important mechanisms for the poor chemotherapy tolerance of the elderly population, which can be significantly improved by short-term DR. This study generates new insights into methods for improving the chemotherapeutic prognosis by increasing the chemotherapy tolerance and safety of patients with malignant tumors.

Dietary restriction mitigates the age-associated decline in mouse B cell receptor repertoire diversity

Aging impairs the capacity to respond to novel antigens, reducing immune protection against pathogens and vaccine efficacy. Dietary restriction (DR) extends life- and health span in diverse animals. However, little is known about the capacity of DR to combat the decline in immune function. Here, we study the changes in B cell receptor (BCR) repertoire during aging in DR and control mice. By sequencing the variable region of the BCR heavy chain in the spleen, we show that DR preserves diversity and attenuates the increase in clonal expansions throughout aging. Remarkably, mice starting DR in mid-life have repertoire diversity and clonal expansion rates indistinguishable from chronic DR mice. In contrast, in the intestine, these traits are unaffected by either age or DR. Reduced within-individual B cell repertoire diversity and increased clonal expansions are correlated with higher morbidity, suggesting a potential contribution of B cell repertoire dynamics to health during aging.

Alterations of the gut microbiome and metabolic profile in CVB3-induced mice acute viral myocarditis

BACKGROUND

Acute viral myocarditis (AVMC) is an inflammatory disease of the myocardium. Evidence indicates that dysbiosis of gut microbiome and related metabolites intimately associated with cardiovascular diseases through the gut-heart axis.

METHODS

We built mouse models of AVMC, then applied 16 S rDNA gene sequencing and UPLC-MS/MS metabolomics to explore variations of gut microbiome and disturbances of cardiac metabolic profiles.

RESULTS

Compared with Control group, analysis of gut microbiota showed lower diversity in AVMC, decreased relative abundance of genera mainly belonging to the phyla Bacteroidetes, and increased of phyla Proteobacteria. Metabolomics analysis showed disturbances of cardiac metabolomics, including 62 increased and 84 decreased metabolites, and mainly assigned to lipid, amino acid, carbohydrate and nucleotide metabolism. The steroid hormone biosynthesis, cortisol synthesis and secretion pathway were particularly enriched in AVMC. Among them, such as estrone 3-sulfate, desoxycortone positively correlated with disturbed gut microbiome.

CONCLUSION

In summary, both the structure of the gut microbiome community and the cardiac metabolome were significantly changed in AVMC. Our findings suggest that gut microbiome may participate in the development of AVMC, the mechanism may be related to its role in dysregulated metabolites such as steroid hormone biosynthesis.

A nexus of dietary restriction and gut microbiota: Recent insights into metabolic health

In recent times, dietary restriction (DR) has received considerable attention for its promising effects on metabolism and longevity. Previous studies on DR have mainly focused on the health benefits produced by different restriction patterns, whereas comprehensive reviews of the role of gut microbiota during DR are limited. In this review, we discuss the effects of caloric restriction, fasting, protein restriction, and amino acid restriction from a microbiome perspective. Furthermore, the underlying mechanisms by which DR affects metabolic health by regulating intestinal homeostasis are summarized. Specifically, we reviewed the impacts of different DRs on specific gut microbiota. Additionally, we put forward the limitations of the current research and suggest the development of personalized microbes-directed DR for different populations and corresponding next-generation sequencing technologies for accurate microbiological analysis. DR effectively modulates the composition of the gut microbiota and microbial metabolites. In particular, DR markedly affects the rhythmic oscillation of microbes which may be related to the circadian clock system. Moreover, increasing evidence supports that DR profoundly improves metabolic syndrome, inflammatory bowel disease, and cognitive impairment. To summarize, DR may be an effective and executable dietary manipulation strategy for maintaining metabolic health, however, further investigation is needed to elucidate the underlying mechanisms.

Calorie restriction ameliorates hyperglycemia, modulates the disordered gut microbiota, and mitigates metabolic endotoxemia and inflammation in type 2 diabetic rats

PURPOSE

The effects of calorie restriction (CR) on gut microbiota and the mechanism of CR ameliorating hyperglycemia in streptozotocin (STZ)-induced T2DM model rats were explored.

METHODS

High-fat diet and STZ injection were applied to induce T2DM model rats. Rats were divided into the following three groups: the control-diet ad libitum group, the T2DM model group fed with ad libitum diet, and the T2DM group fed with 30% restriction diet. 16S rRNA sequencing was used to determine the bacterial communities. Lipopolysaccharide (LPS)-binding protein (LBP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured.

RESULTS

Glucose tolerance and insulin sensitivity were improved by CR, as well as the levels of fasting and random plasma glucose. Besides, CR not only modulated the overall structure of gut microbiota but also had selective enrichment in anti-inflammatory bacteria such as Lachnospiraceae_NK4A136_group, Ruminococcaceae_9, Allobaculum, Alistipes, and Oscillibacter, and decreased pro-inflammatory pathogenic bacteria such as Bacteroides, Lachnoclostridium, and Bifidobacterium. Tax4Fun indicated that CR could regulate related functional pathways such as lipopolysaccharide biosynthesis, and the plasma levels of LBP, IL-6, and TNF-α were markedly reduced by CR, suggesting the mechanism of CR ameliorating hyperglycemia may associate with the modulation of disordered gut microbiota and the reduction of metabolic endotoxemia and inflammation.

CONCLUSION

CR could ameliorate hyperglycemia, the mechanism of which may associate with the alteration of the overall structure of gut microbiota, restoration of disordered microbiota function, and the downregulation of metabolic endotoxemia and inflammation in diabetic rats.

Impact of caloric restriction on the gut microbiota

Caloric restriction (CR) and related time-restricted diets have been popularized as means of preventing metabolic disease while improving general well-being. However, evidence as to their long-term efficacy, adverse effects, and mechanisms of activity remains incompletely understood. The gut microbiota is modulated by such dietary approaches, yet causal evidence to its possible downstream impacts on host metabolism remains elusive. Herein, we discuss the positive and adverse influences of restrictive dietary interventions on gut microbiota composition and function, and their collective impacts on host health and disease risk. We highlight known mechanisms of microbiota influences on the host, such as modulation of bioactive metabolites, while discussing challenges in achieving mechanistic dietary-microbiota insights, including interindividual variability in dietary responses as well as other methodological and conceptual challenges. In all, causally understanding the impact of CR approaches on the gut microbiota may enable to better decode their overall influences on human physiology and disease.

Effects of dietary restriction on gut microbiota and CNS autoimmunity

Multiple sclerosis (MS) is the most common central nervous system (CNS) autoimmune disease. It is due to the interplay of genetic and environmental factors. Current opinion is that diet could play a pathogenic role in disease onset and development. Dietary restriction (DR) without malnutrition markedly improves health and increases lifespan in multiple model organisms. DR regimens that utilize continuous or intermittent food restriction can induce anti-inflammatory, immuno-modulatory and neuroendocrine adaptations promoting health. These adaptations exert neuroprotective effects in the main MS animal model, experimental autoimmune encephalomyelitis (EAE). This review summarizes the current knowledge on DR-induced changes in gut microbial composition and metabolite production and its impact on underlying functional mechanisms. Studies demonstrating the protective effects of DR regimens on EAE and people with MS are also presented. This is a rapidly developing research field with important clinical implications for personalized dietary interventions in MS prevention and treatment.

Extension of the Life Span by Acarbose: Is It Mediated by the Gut Microbiota?

Acarbose can extend the life span of mice through a process involving the gut microbiota. Several factors affect the life span, including mitochondrial function, cellular senescence, telomere length, immune function, and expression of longevity-related genes. In this review, the effects of acarbose-regulated gut microbiota on the life span-influencing factors have been discussed. In addition, a novel theoretical basis for improving our understanding of the mechanisms by which acarbose extends the life span of mice has been suggested.

Evaluating the reparative effects and the mechanism of action of docosahexaenoic acid on azithromycin-induced lipid metabolism dysfunction

To explore the reparative effects of DHA on the gut microbiome disturbance and dysfunctional lipid metabolism caused by long-term antibiotic therapy, it was tested on an azithromycin (AZI) mouse antibiotic model. Thirty specific-pathogen-free BALB/c mice (SPF grade, half male and half female) were randomly separated into three groups (n = 10, 5 male and 5 female): control group (CK), azithromycin natural recovery group (AZI) and DHA group (DHA). High-throughput sequencing and bioinformatics methods were used to analyze the gut microbiome. ELASE kits were used to measure blood lipid, lipids in the liver, and bile salt hydrolase (BSH) levels in feces. Gas chromatography and UPLC-MS/MS were employed to detect DHA and bile acids contents in liver, respectively. Real-time polymerase chain reaction (RT-PCR) was used to measure the expression of key enzymes involved in lipid metabolism. Long-term AZI treatment led to dyslipidemia, gut microbiome disturbance and anxious behaviors in the mouse model. DHA was found to significantly improve the dyslipidemia and anxiety-like behaviors induced by AZI. DHA had no effect on the structure of gut microbiome and bile acids contents but increased the content of the metabolic enzyme BSH in gut microbiota and normalized the expression of enzymes involved in lipid metabolism.

Dietary restrictions modulate the gut microbiota: Implications for health and disease

The health benefits of carefully restricting the energy intake in a strategic manner whilst avoiding malnutrition are widely discussed. In the recent years, the great impact of the gut microbiota on its host has been clarified more and more. Since the gut microbiota produces a number of metabolites and molecules that can affect host metabolism, modulating it with dietary restriction can influence the health and the progression of disease of its host on various levels. This review comprises 15 studies investigating the effect of different variants of fasting and caloric restriction on the gastrointestinal microbiome and its metabolites. The data suggest that changing the gut microbiota composition by dietary restriction has the potential to positively influence the progression of several diseases such as obesity, diabetes, neurological diseases or inflammatory bowel disease. Finally, the relevance of the findings for clinical practice is evaluated and approaches for future research are proposed.

The relevance of DHA with modulating of host-gut microbiome signatures alterations and repairing of lipids metabolism shifts

Huge of previous reports recommended that gut microbiome have a crucial role in the human health and its change was profound impact for the metabolic improvements associated with lipids metabolism. In order to explore the relevance of a direct dysbiosis effect of gut microbiome on lipids metabolism shifts and repaired position of DHA, we built the animal model for the study with gut microbiome dysbiosis administrated by i.g. with CRO and intervened by DHA in the present work. Gut microbiome was analyzed by high throughput sequencing and bioinformatics analyses of bacteria. The composition of fatty acids and short chain fatty acids (SCFAs) were determined by gas chromatography. Blood lipids and bile acids were assayed by kit and UPLC-MS/MS, respectively. The expressions of enzymes of long chain fatty acid metabolism were analyzed by qRT-PCR. The results showed that gut microbiome dysbiosis caused lipid metabolism abnormal, and DHA was able to repair the lipids metabolism shifts resulted from gut microbiome dysbiosis. DHA could modulate host-gut microbiome signatures, improve concentrations of SCFAs, regulate fatty acids metabolism but modify bile acid profiles. In conclusion, we considered that DHA repaired lipid metabolism by modulating gut microbiome and regulating fatty acids metabolism pathway.

Calorie restriction prevents age-related changes in the intestinal microbiota

The effect of calorie restriction (CR) on the microbiome, fecal metabolome, and colon transcriptome of adult and old male mice was compared. Life-long CR increased microbial diversity and the Bacteroidetes/Firmicutes ratio and prevented the age-related changes in the microbiota, shifting it to a younger microbial and fecal metabolite profile in both C57BL/6JN and B6D2F1 mice. Old mice fed CR were enriched in the Rikenellaceae, S24-7 and Bacteroides families. The changes in the microbiome that occur with age and CR were initiated in the cecum and further modified in the colon. Short-term CR in adult mice had a minor effect on the microbiome but a major effect on the transcriptome of the colon mucosa. These data suggest that CR has a major impact on the physiological status of the gastrointestinal system, maintaining it in a more youthful state, which in turn could result in a more diverse and youthful microbiome.

Young at Gut-Turning Back the Clock with the Gut Microbiome

Over the past century, we have witnessed an increase in life-expectancy due to public health measures; however, we have also seen an increase in susceptibility to chronic disease and frailty. Microbiome dysfunction may be linked to many of the conditions that increase in prevalence with age, including type 2 diabetes, cardiovascular disease, Alzheimer's disease, and cancer, suggesting the need for further research on these connections. Moreover, because both non-modifiable (e.g., age, sex, genetics) and environmental (e.g., diet, infection) factors can influence the microbiome, there are vast opportunities for the use of interventions related to the microbiome to promote lifespan and healthspan in aging populations. To understand the mechanisms mediating many of the interventions discussed in this review, we also provide an overview of the gut microbiome's relationships with the immune system, aging, and the brain. Importantly, we explore how inflammageing (low-grade chronic inflammation that often develops with age), systemic inflammation, and senescent cells may arise from and relate to the gut microbiome. Furthermore, we explore in detail the complex gut-brain axis and the evidence surrounding how gut dysbiosis may be implicated in several age-associated neurodegenerative diseases. We also examine current research on potential interventions for healthspan and lifespan as they relate to the changes taking place in the microbiome during aging; and we begin to explore how the reduction in senescent cells and senescence-associated secretory phenotype (SASP) interplay with the microbiome during the aging process and highlight avenues for further research in this area.

Effect of Gender and Various Diets on Bile Acid Profile and Related Genes in Mice

Diet is an important factor for many diseases. Previous studies have demonstrated that several diets had remarkable effects on bile acid (BA) homeostasis, but no comprehensive information for both genders has been reported. Therefore, the current study characterized the nine most used laboratory animal diets fed to both genders of mice for a comparable evaluation of the topic. The results revealed that marked gender difference of BA homeostasis is ubiquitous in mice fed the various diets, and of the nine diets fed to mice, the atherogenic and calorie-restricted diets had the most marked effects on BA homeostasis, followed by the laboratory chow and essential fatty acid-deficient diets. More specifically, females had higher concentrations of total BAs in serum when fed six of the nine diets compared with male mice, and 26 of the 35 BA-related genes had marked gender difference in mice fed at least one diet. Although mice fed the calorie-restricted and atherogenic diets had increased BA, which was more pronounced in serum than liver, the intestinal farnesoid X nuclear receptor-fibroblast growth factor 15 axis changed in the opposite direction and resulted in different hepatic expression patterns of Cyp7a1 Compared with AIN-93M purified diet, higher hepatic expression of multidrug resistance-associated protein 3 was the only alteration in mice fed the laboratory chow diet. The other diets had little or no effect on BA concentrations in the liver and plasma or in the expression of BA-related genes. This study indicates that gender, the atherogenic diet, and the calorie-restricted diet have the most marked effects on BA homeostasis. SIGNIFICANCE STATEMENT: Previous evidence suggested that various diets have effect on bile acid (BA) homeostasis; however, it is not possible to directly compare these findings, as they are all from different studies. The current study was the first to systematically investigate the influence of the nine most used experimental mouse diets on BA homeostasis and potential mechanism in both genders of mice and indicates that gender, the atherogenic diet, and the calorie-restricted diet have the most marked effects on BA homeostasis, which will aid future investigations.

The effect of energy restriction on development and progression of chronic kidney disease: review of the current evidence

Energy restriction (ER) has anti-ageing effects and probably protects from a range of chronic diseases including cancer, diabetes and chronic kidney disease (CKD). Specifically, ER has a positive impact on experimental kidney ageing, CKD (diabetic nephropathy, polycystic kidney disease) and acute kidney injury (nephrotoxic, ischaemia-reperfusion injury) through such mechanisms as increased autophagy, mitochondrial biogenesis and DNA repair, and decreased inflammation and oxidative stress. Key molecules contributing to ER-mediated kidney protection include adenosine monophosphate-activated protein kinase, sirtuin-1 and PPAR-γ coactivator 1α. However, CKD is a complex condition, and ER may potentially worsen CKD complications such as protein-energy wasting, bone-mineral disorders and impaired wound healing. ER mimetics are drugs, such as metformin and Na-glucose co-transporter-2 which mimic the action of ER. This review aims to provide comprehensive data regarding the effect of ER on CKD progression and outcomes.

Improvement of intestinal stem cells and barrier function via energy restriction in middle-aged C57BL/6 mice

This study aimed to reveal the impact of energy restriction on the intestine via structural and molecular changes in terms of intestinal stem cell (ISC) function, ISC niche, intestinal epithelial barrier function, and intestinal immune function. Female C57BL/6J mice, aged 12 months, fed a commercial chow were used in this study. The ISC function, ISC niche, intestinal epithelial barrier function, and intestinal immune function were assessed. Energy restriction reversed aging-induced intestinal shortening and made the crypts shallower. The intestinal epithelial cells isolated from the intestine showed a significant increase in the expression levels of stem cell-associated genes in small intestinal epithelial cells as detected by flow cytometry. Despite the increase in the number of stem cells and the expression levels of markers, no increase or decrease was found in the enteroid complexity of the small intestine and colonic enteroid formation in vitro. The colonic mucous layer was measured in mice of the energy restricted (ER)-treated group to investigate the epithelial barrier function in the colon. The results revealed that the barrier was more complete. The fluorescence intensity of tight junction markers claudin-2 and zonula occludens-1 increased and the mRNA expression profiles of monocyte chemotactic protein 1 and interleukin-6 decreased in the colon of mice in the ER-treated group. The beneficial effects of ER on the colon in terms of the integrity of the mucosal barrier and alleviation of inflammation were confirmed, thus highlighting the importance of modulating the intestinal function in developing effective antiaging dietary interventions.

First Insights into the Urinary Metabolome of Captive Giraffes by Proton Nuclear Magnetic Resonance Spectroscopy

The urine from 35 giraffes was studied by untargeted ¹H-NMR, with the purpose of obtaining, for the first time, a fingerprint of its metabolome. The metabolome, as downstream of the transcriptome and proteome, has been considered as the most representative approach to monitor the relationships between animal physiological features and environment. Thirty-nine molecules were unambiguously quantified, able to give information about diet, proteins digestion, energy generation, and gut-microbial co-metabolism. The samples collected allowed study of the effects of age and sex on the giraffe urinary metabolome. In addition, preliminary information about how sampling procedure and pregnancy could affect a giraffe’s urinary metabolome was obtained. Such work could trigger the setting up of methods to non-invasively study the health status of giraffes, which is utterly needed, considering that anesthetic-related complications make their immobilization a very risky practice.

MicroRNA 16-5p is upregulated in calorie-restricted mice and modulates inflammatory cytokines of macrophages

Caloric restriction (CR) has long been known to increase median and maximal lifespans and to decrease mortality and morbidity in short-lived animal models, likely by altering fundamental biological processes that regulate aging and longevity. However, the detailed mechanisms of immunomodulation by CR remain unclear. In this study, we established a mouse model for CR and analyzed the changes of immune cells in these mice. The CR mice fed a calorie-restricted diet for 4 weeks had lower body weight and fat mass compared with control mice. The proportions of CD4⁺, CD8⁺, and naïve CD4⁺ T cells in spleen cells from CR mice were higher than those in of control mice. Additionally, the proportion of CD8⁺ T cells was significantly decreased and the mRNA expression of proinflammatory cytokines in the colon of CR mice was significantly decreased compared with those of control mice. To determine the effect of CR on microRNA (miRNA) expression, serum and tissues were collected from mice and the expression level of miRNA was analyzed by real-time RT-PCR. As a result, the expressions of miR-16-5p, miR-196b-5p, and miR-218-5p in serum from CR mice were higher than those in control mice. The expression of miR-16-5p increased in the spleen, thymus, colon, and stomach of CR mice compared with expression in control mice. Furthermore, RAW264 cells transfected with a miR-16-5p mimic significantly decreased the mRNA expression of IL-1β, IL-6, and TNF-α under LPS stimulation. These results suggested that miR-16-5p might be a critical factor involving the anti-inflammatory effects of calorie-restricted feeding.

Short-term dietary restriction in old mice rejuvenates the aging-induced structural imbalance of gut microbiota

The world’s aging population is growing rapidly. Incidences of multiple pathologies, such as abdominal obesity, cardiovascular and cerebrovascular diseases, type 2 diabetes, and malignant neoplasms, increase sharply with age. Aged individuals possess a significantly shifted composition of gut microbiota, which is suggested to play important roles in aging associated pathologies. Whether the existing shifted structural composition of microbiota in aged populations can be reverted non-pharmacologically has not been studied so far. Here, we show an intestinal flora imbalance in old C57BL/6J mice with a remarkable dominant proportion of microbes promoting lipid metabolism and inflammation. Intriguingly, short-term (2 months) dietary restriction was enough to significantly revert the imbalance of intestinal flora in aged mice toward a more balanced structural composition as shown in young mice. Our study provides the first evidence that short-term dietary restriction in old mice can restore the already dysfunctional aged gut microbiota. Our study provides the first evidence that short-term dietary restriction in old mice can restore the already dysfunctional aged gut microbiota, which may help ameliorate aging-related disorders plaguing the vast elderly population.

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.

Effects of the intake of white wheat bread added with garlic and resistant starch: action on calcium bioavailability and metabolic parameters of growing Wistar rats

Functional bread with resistant starch and garlic improved the metabolism of calcium and lipids and the growth of beneficial gut microbiota.