Influence of Altered Gut Microbiota Composition on Aging and Aging-Related Diseases

Gene prediction of immune cells association between gut microbiota and colorectal cancer: a Mendelian randomization study

Background

An increasing number of studies have revealed that gut microbiota influences the development and progression of Colorectal cancer (CRC). However, whether a causal relationship exists between the two remains unclear, and the role of immune cells in this context is not well understood.

Objective

To elucidate the causal relationship between gut microbiota and CRC and to explore the potential mediating role of circulating immune cells.

Materials and methods

To analyze the causal relationship between gut microbiota and CRC, we employed a univariable Mendelian randomization (UVMR) approach. Subsequently, a two-step multivariable Mendelian randomization (MVMR) to assess the potential mediating role of circulating immune cells. Primarily, applied the Inverse-Variance Weighted method to evaluate the causal relationship between exposure and outcome. To ensure the robustness of the results linking gut microbiota and CRC, we validated the findings using Robust Inverse-Variance Weighted, Penalized Inverse-Variance Weighted, and Penalized Robust Inverse-Variance Weighted methods. Additionally, we employed MR-Egger Intercept to mitigate the influence of horizontal pleiotropy. MR-PRESSO was used to detect and correct outliers by excluding anomalous instrumental variables. Finally, we supplemented our analysis with methods such as Bayesian Weighted Mendelian Randomization (BWMR), Maximum-Likelihood, Lasso, Debiased Inverse Variance Weighted, and Contamination Mixture to establish a robust and compelling causal relationship.

Results

After accounting for reverse causality, horizontal pleiotropy, and various methodological corrections, Bifidobacterium kashiwanohense, GCA-900066755 sp900066755, Geminocystis, and Saccharofermentanaceae exhibited strong and robust causal effects on CRC. Specifically, CD40 on monocytes (2.82%) and CD45 on CD33+HLA-DR+CD14- cells (12.87%) mediated the causal relationship between Bifidobacterium kashiwanohense and CRC risk. Furthermore, CD45 on CD33-HLA-DR+ (3.94%) mediated the causal relationship between GCA-900066755 sp900066755 and CRC risk. Additionally, terminally differentiated CD4+T cells (11.55%) mediated the causal relationship between Geminocystis and CRC risk. Lastly, CD40 on monocytes (2.35%), central memory CD4+T cells (5.76%), and CD28 on CD28+CD45RA+CD8+T cells (5.00%) mediated the causal relationship between Saccharofermentanaceae and CRC risk.

Conclusion

Our mediation MR analysis provides genetic evidence suggesting that circulating immune cells may mediate the causal relationship between gut microbiota and CRC. The identified associations and mediation effects offer new insights into potential therapeutic avenues for CRC.

Impact of Gut Microbiota in Brain Ageing: Polyphenols as Beneficial Modulators

Brain ageing is a complex physiological process that includes several mechanisms. It is characterized by neuronal/glial dysfunction, alterations in brain vasculature and barriers, and the decline in brain repair systems. These disorders are triggered by an increase in oxidative stress and a proinflammatory state, without adequate antioxidant and anti-inflammatory systems, as it occurs in young life stages. This state is known as inflammaging. Gut microbiota and the gut–brain axis (GBA) have been associated with brain function, in a bidirectional communication that can cause loss or gain of the brain’s functionality. There are also intrinsic and extrinsic factors with the ability to modulate this connection. Among the extrinsic factors, the components of diet, principally natural components such as polyphenols, are the most reported. The beneficial effects of polyphenols in brain ageing have been described, mainly due to their antioxidants and anti-inflammatory properties, including the modulation of gut microbiota and the GBA. The aim of this review was, by following the canonical methodology for a state-of-the-art review, to compose the existing evidenced picture of the impact of the gut microbiota on ageing and their modulation by polyphenols as beneficial molecules against brain ageing.

Gut-derived β-amyloid: Likely a centerpiece of the gut-brain axis contributing to Alzheimer's pathogenesis

Peripheral β-amyloid (Aβ), including those contained in the gut, may contribute to the formation of Aβ plaques in the brain, and gut microbiota appears to exert an impact on Alzheimer's disease (AD) via the gut-brain axis, although detailed mechanisms are not clearly defined. The current study focused on uncovering the potential interactions among gut-derived Aβ in aging, gut microbiota, and AD pathogenesis. To achieve this goal, the expression levels of Aβ and several key proteins involved in Aβ metabolism were initially assessed in mouse gut, with key results confirmed in human tissue. The results demonstrated that a high level of Aβ was detected throughout the gut in both mice and human, and gut Aβ42 increased with age in wild type and mutant amyloid precursor protein/presenilin 1 (APP/PS1) mice. Next, the gut microbiome of mice was characterized by 16S rRNA sequencing, and we found the gut microbiome altered significantly in aged APP/PS1 mice and fecal microbiota transplantation (FMT) of aged APP/PS1 mice increased gut BACE1 and Aβ42 levels. Intra-intestinal injection of isotope or fluorescence labeled Aβ combined with vagotomy was also performed to investigate the transmission of Aβ from gut to brain. The data showed that, in aged mice, the gut Aβ42 was transported to the brain mainly via blood rather than the vagal nerve. Furthermore, FMT of APP/PS1 mice induced neuroinflammation, a phenotype that mimics early AD pathology. Taken together, this study suggests that the gut is likely a critical source of Aβ in the brain, and gut microbiota can further upregulate gut Aβ production, thereby potentially contributing to AD pathogenesis.

Intestinal microbial diversity in female rhesus (Macaca mulatta) at different physiological periods

To explore the relationship between the changes in the physiological period and the fecal microbial population of female rhesus monkeys by measuring microbial composition of fecal samples and the serum hormones. Blood and fecal samples were collected from six female adult rhesus monkeys during the menstrual period (MP), ovulation period (OP), and Luteal period (LP). Serum estradiol (E2) and progesterone (P) levels were determined by the chemiluminescence method and the stool samples were subjected to high-throughput 16S rRNA sequencing. The highest level of E2 and P secretions were during the MP, and LP, respectively. Stool samples produced valid sequences and the number of operational taxonomic unit/OTU was: 810056/3756 (MP), 845242/4159 (OP), 881560/3970 (LP). At the phylum level, the three groups of Firmicutes and Bacteroides accounted for > 95%. The dominant flora at the LP was Bacteroides (53.85%), the dominant flora at the MP and OP was Firmicutes, 64.08 and 56.53%, respectively. At the genus level, the dominant genus at the LP was Prevotella, the dominant genera at the MP were Prevotella, Oncococcus, Streptococcus, and Kurtella. The dominant genera at OP were Prevotella and Nocococcus. At the phylum level, P levels were negatively correlated to Firmicutes, Actinomycetes Actinobacteria, and Fibrobacteres, but positively correlated to Bacteroidetes. Likewise, E2 was positively correlated to Proteobacteria but negatively correlated to Euryarchaeota. At the genus level, P hormone showed a significant correlation with 16 bacterial species, and E2 was significantly correlated to seven bacterial species. Function prediction analysis revealed a high similarity between the MP and OP with six differentially functional genes (DFGs) between them and 11 DFGs between OP and LP (P < 0.05). Fecal microbiota types of female rhesus monkeys varied with different stages of the menstrual cycle, possibly related to changes in hormone levels.

Lactobacillus paracasei M11-4 isolated from fermented rice demonstrates good antioxidant properties in vitro and in vivo

BACKGROUND

Probiotics are defined as microorganisms that can exert health benefits for the host. Among the recognized probiotics, Lactobacillus paracasei are one of the most frequently used probiotics in humans. The L. paracasei strain M11-4, isolated from fermented rice (which could ferment soymilk within a short curd time) and fermented soymilk presented high viability, acceptable flavor, and antioxidant activity, which revealed that the strain maybe have a potential antioxidant value. Therefore, it is necessary to further explore the antioxidant activity of L. paracasei strain M11-4.

RESULTS

The radical scavenging activities, lipid peroxidation inhibition, and reducing power of L. paracasei M11-4 were the highest in the fermentation culture without cells, whereas the activities of other antioxidant enzymes of L. paracasei M11-4 were high in the cell-free extract and bacterial suspension. Moreover, L. paracasei M11-4 exerted its antioxidant effect by upregulating the gene expression of its antioxidant enzymes - the thioredoxin and glutathione systems - when hydrogen peroxide existed. Supplementation of rats with L. paracasei M11-4 effectively alleviated d-galactose-induced oxidative damage in the liver and serum and prevented d-galactose-induced changes to intestinal microbiota. Supplementation with L. paracasei M11-4 also reduced the elevated expression of thioredoxin and glutathione system genes induced by d-galactose.

CONCLUSION

L. paracasei M11-4 has good antioxidant properties both in vitro and in vivo, and its antioxidant mechanism was studied at the molecular level. © 2021 Society of Chemical Industry.

Moxibustion may delay the aging process of Wistar rats by regulating intestinal microbiota

As one of the important treatments of health care and anti-aging in traditional Chinese medicine (TCM), moxibustion has been proved to have the effects of scavenging free radicals, anti-oxidation, reducing inflammatory reaction, regulating immunity and so on. Recent studies have shown that intestinal microbiota affect the process of aging. The relationship between aging, moxibustion and intestinal microbiota is still unclear. In this study, we explored the effects of moxibustion at Guanyuan (RN4) acupoint on intestinal microbiota, short-chain fatty acids and immunological characteristics of young and elder female Wistar rats to explore the relationship between aging, moxibustion and intestinal microbiota. Six 12-week-old female Wistar rats were young group (Y), and twelve 36-week-old female Wistar rats were randomly divided into elder group (C) and moxibustion group (M). The rats in M group were received mild moxibustion at Guanyuan (RN4) acupoint, 20 min/d for 40 days. The rats in Y group and C group were not given any therapeutic intervention. The results showed that moxibustion increased the abundance of intestinal probiotics (mainly Lactobacillus) and the level of short chain fatty acids, the microcirculation blood flow around Guanyuan (RN4) acupoint was also significantly improved in elder rats. In addition, the expression of MyD88, MAPK, TRAF6, NF-κB in intestinal tissue was down-regulated, and the levels of inflammatory cytokines in intestinal were decreased.

Emerging Interrelationship Between the Gut Microbiome and Cellular Senescence in the Context of Aging and Disease: Perspectives and Therapeutic Opportunities

The significance of diversity, composition, and functional attributes of the gut microbiota in shaping human health is well recognized. Studies have shown that gut microbiota is closely linked to human aging, and changes in the gut microbiome can predict human survival and longevity. In addition, a causal relationship between gut microbiota dysbiosis and chronic age-related disorders is also becoming apparent. Recent advances in our understanding of the cellular and molecular aspects of biological aging have revealed a cellular senescence-centric view of the aging process. However, the association between the gut microbiome and cellular senescence is only beginning to be understood. The present review provides an integrative view of the evolving relationship between the gut microbiome and cellular senescence in aging and disease. Evidence relating to microbiome-mediated modulation of senescent cells, as well as senescent cells-mediated changes in intestinal homeostasis and diseases, have been discussed. Unanswered questions and future research directions have also been deliberated to truly ascertain the relationship between the gut microbiome and cellular senescence for developing microbiome-based age-delaying and longevity-promoting therapies.

Integrated Multi-Omics for Novel Aging Biomarkers and Antiaging Targets

Aging is closely related to the occurrence of human diseases; however, its exact biological mechanism is unclear. Advancements in high-throughput technology provide new opportunities for omics research to understand the pathological process of various complex human diseases. However, single-omics technologies only provide limited insights into the biological mechanisms of diseases. DNA, RNA, protein, metabolites, and microorganisms usually play complementary roles and perform certain biological functions together. In this review, we summarize multi-omics methods based on the most relevant biomarkers in single-omics to better understand molecular functions and disease causes. The integration of multi-omics technologies can systematically reveal the interactions among aging molecules from a multidimensional perspective. Our review provides new insights regarding the discovery of aging biomarkers, mechanism of aging, and identification of novel antiaging targets. Overall, data from genomics, transcriptomics, proteomics, metabolomics, integromics, microbiomics, and systems biology contribute to the identification of new candidate biomarkers for aging and novel targets for antiaging interventions.

Aronia melanocarpa polysaccharide ameliorates inflammation and aging in mice by modulating the AMPK/SIRT1/NF-κB signaling pathway and gut microbiota

Aronia melanocarpa is a natural medicinal plant that has a variety of biological activities, its fruit is often used for food and medicine. Aronia melanocarpa polysaccharide (AMP) is the main component of the Aronia melanocarpa fruit. This research evaluated the delay and protection of AMP obtained from Aronia melanocarpa fruit on aging mice by D-Galactose (D-Gal) induction and explored the effect of supplementing AMP on the metabolism of the intestinal flora of aging mice. The aging model was established by intraperitoneal injection of D-Gal (200 mg/kg to 1000 mg/kg) once per 3 days for 12 weeks. AMP (100 and 200 mg/kg) was given daily by oral gavage after 6 weeks of D-Gal-induced. The results showed that AMP treatment significantly improved the spatial learning and memory impairment of aging mice determined by the eight-arm maze test. H&E staining showed that AMP significantly reversed brain tissue pathological damage and structural disorders. AMP alleviated inflammation and oxidative stress injury in aging brain tissue by regulating the AMPK/SIRT1/NF-κB and Nrf2/HO-1 signaling pathways. Particularly, AMP reduced brain cell apoptosis and neurological deficits by activating the PI3K/AKT/mTOR signaling pathway and its downstream apoptotic protein family. Importantly, 16S rDNA analysis indicated the AMP treatment significantly retarded the aging process by improving the composition of intestinal flora and abundance of beneficial bacteria. In summary, this study found that AMP delayed brain aging in mice by inhibiting inflammation and regulating intestinal microbes, which providing the possibility for the amelioration and treatment of aging and related metabolic diseases.

1H NMR-Based Fecal Metabolomics Reveals Changes in Gastrointestinal Function of Aging Rats Induced by d-Galactose

d-galactose (d-gal) is widely used to induce aging. However, it is still unclear whether long-term injection of d-gal affects the gastrointestinal functions of aging rats, and how. In this study, we investigated the effects of d-gal on the gastrointestinal functions of aging rats, especially from the perspective of fecal metabolomics. Biochemical and behavioral analyses were performed. Besides, a ¹H NMR-based metabolomics approach was built and applied in combination with multivariate data analysis including principal components analysis (PCA) and orthogonal partial least squares-discriminate analysis (OPLS-DA). Regarding gastrointestinal functions, d-gal significantly decreased the small intestine propulsion rates and prolonged gastrointestinal transit time. In addition, d-gal significantly increased the oxidative damages. PCA results showed that d-gal interrupted the metabolic profiles of endogenous small molecules in aging rats. Furthermore, OPLS-DA showed that 40 metabolites were screened and identified to be involved in the disruption of gastrointestinal functions in aging rats. Accordingly, seven metabolic pathways were recognized as the most influenced pathways associated with gastrointestinal functions of aging rats induced by d-gal, including amino acid metabolism, energy metabolism, intestinal flora metabolism, and metabolism of short chain fatty acids. It is the first report to investigate the effects and underlying mechanisms of d-gal on gastrointestinal functions of aging rats from the perspective of fecal metabolomics. The current results are conducive to further comprehensively understand d-gal-induced aging and will expand the applications of d-gal in pharmacological researches.

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.

Host age is not a consistent predictor of microbial diversity in the coral Porites lutea

Corals harbour diverse microbial communities that can change in composition as the host grows in age and size. Larger and older colonies have been shown to host a higher diversity of microbial taxa and this has been suggested to be a consequence of their more numerous, complex and varied micro-niches available. However, the effects of host age on community structure and diversity of microbial associates remain equivocal in the few studies performed to date. To test this relationship more robustly, we use established techniques to accurately determine coral host age by quantifying annual skeletal banding patterns, and utilise high-throughput sequencing to comprehensively characterise the microbiome of the common reef-building coral, Porites lutea. Our results indicate no clear link between coral age and microbial diversity or richness. Different sites display distinct age-dependent diversity patterns, with more anthropogenically impacted reefs appearing to show a winnowing of microbial diversity with host age, possibly a consequence of corals adapting to degraded environments. Less impacted sites do not show a signature of winnowing, and we observe increases in microbial richness and diversity as the host ages. Furthermore, we demonstrate that corals of a similar age from the same reef can show very different microbial richness and diversity.

Review on the Alteration of Gut Microbiota: The Role of HIV Infection and Old Age

Human immunodeficiency virus (HIV) infection results in gut microbiota alteration and this is associated with immune activation and chronic inflammation. The gastrointestinal tract is a primary site of viral replication and thus HIV-induced loss of T-helper (Th) cells in the gut causes impairments in intestinal barriers, resulting in disruptions in intestinal immunity and precipitating into gut dysbiosis. Here, we show that late HIV diagnosis can negatively affect the immunological, virological, and clinical prognosis of the patients with its higher implication at an older age. Further, the review indicates that antiretroviral therapy affects the gut microbiota. We discussed the use of probiotics and prebiotics that have been indicated to play a promising role in reversing gut microbiota alteration in HIV patients. Though there are several studies reported with regard to such alterations in gut microbiota regarding HIV infection, there is a need to provide comprehensive updates. It is, therefore, the objective of this review to present most recently available evidence on the alteration of gut microbiota among HIV patients.

Potential Preventive Strategies for Amyotrophic Lateral Sclerosis

It may seem useless to propose preventive measures for a disease without established pathogenesis and successful therapy, such as amyotrophic lateral sclerosis (ALS). However, we will show that ALS shares essential molecular mechanisms with aging and that established anti-aging strategies, such as healthy diet or individually adjusted exercise, may be successfully applied to ameliorate the condition of ALS patients. These strategies might be applied for prevention if persons at ALS risk could be identified early enough. Recent research advances indicate that this may happen soon.

A human-origin probiotic cocktail ameliorates aging-related leaky gut and inflammation via modulating the microbiota/taurine/tight junction axis

Inflammation is a major risk factor of morbidity and mortality in older adults. Although its precise etiology is unknown, low-grade inflammation in older adults is commonly associated with increased intestinal epithelial permeability (leaky gut) and abnormal (dysbiotic) gut microbiota. The increasing older population and lack of treatments to reduce aging-related microbiota dysbiosis, leaky gut, and inflammation culminates in a rise in aging-related comorbidities, constituting a significant public health concern. Here, we demonstrate that a human-origin probiotic cocktail containing 5 Lactobacillus and 5 Enterococcus strains isolated from healthy infant gut prevented high-fat diet-induced (HFD-induced) microbiota dysbiosis, leaky gut, inflammation, metabolic dysfunctions, and physical function decline in older mice. Probiotic-modulated gut microbiota primarily reduced leaky gut by increasing tight junctions, which in turn reduced inflammation. Mechanistically, probiotics modulated microbiota in a way to increase bile salt hydrolase activity, which in turn increased taurine abundance in the gut that stimulated tight junctions and suppressed gut leakiness. Furthermore, in Caenorhabditis elegans, taurine increased life span, reduced adiposity and leaky gut, and enhanced physical function. The results suggest that such probiotic therapies could prevent or treat aging-related leaky gut and inflammation in the elderly.

The Bacterium Akkermansia muciniphila: A Sentinel for Gut Permeability and Its Relevance to HIV-Related Inflammation

Gut dysbiosis, namely dysregulation of the intestinal microbiota, and increased gut permeability lead to enhanced inflammation and are commonly seen in chronic conditions such as obesity and aging. In people living with HIV (PLWH), several lines of evidence suggest that a depletion of gut CD4 T-cells is associated with gut dysbiosis, microbial translocation and systemic inflammation. Antiretroviral therapy (ART) rapidly controls viral replication, which leads to CD4 T-cell recovery and control of the disease. However, gut dysbiosis, epithelial damage and microbial translocation persist despite ART, increasing risk of developing inflammatory non-AIDS comorbidities such as cardiovascular disease, diabetes mellitus, liver steatosis and cancer. In addition to ART, an emerging research priority is to discover strategies to improve the gut microbial composition and intestinal barrier function. Probiotic interventions have been extensively used with controversial benefits in humans. Encouragingly, within the last decade, the intestinal symbiotic bacterium Akkermansia muciniphila has emerged as the “sentinel of the gut.” A lower abundance of A. muciniphila has been shown in diabetic and obese people as well as in PLWH. Interventions with high levels of polyphenols such as tea or diets rich in fruit, the antibiotic vancomycin and the antidiabetic drug metformin have been shown to increase A. muciniphila abundance, contributing to improved metabolic function in diabetic and obese individuals. We hypothesize that gut microbiota rich in A. muciniphila can reduce microbial translocation and inflammation, preventing occurrences of non-AIDS comorbidities in PLWH. To this aim, we will discuss the protective effect of A. muciniphila and its potential applications, paving the way toward novel therapeutic strategies to improve gut health in PLWH.

Metformin effect on gut microbiota: insights for HIV-related inflammation

The gut microbiota is emerging as a prominent player in maintaining health through several metabolic and immune pathways. Dysregulation of gut microbiota composition, also known as dysbiosis, is involved in the clinical outcome of diabetes, inflammatory bowel diseases, cancer, aging and HIV infection. Gut dysbiosis and inflammation persist in people living with HIV (PLWH) despite receiving antiretroviral therapy, further contributing to non-AIDS comorbidities. Metformin, a widely used antidiabetic agent, has been found to benefit microbiota composition, promote gut barrier integrity and reduce inflammation in human and animal models of diabetes. Inspired by the effect of metformin on diabetes-related gut dysbiosis, we herein critically review the relevance of metformin to control inflammation in PLWH. Metformin may improve gut microbiota composition, in turn reducing inflammation and risk of non-AIDS comorbidities. This review will pave the way towards innovative strategies to counteract dysregulated microbiota and improve the lives of PLWH.

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.

Gut microbiota in common elderly diseases affecting activities of daily living

Gut microbiota are involved in the development or prevention of various diseases such as type 2 diabetes, fatty liver, and malignancy such as colorectal cancer, breast cancer and hepatocellular carcinoma. Alzheimer's disease, osteoporosis, sarcopenia, atherosclerotic stroke and cardiovascular disease are major diseases associated with decreased activities of daily living (ADL), especially in elderly people. Recent analyses have revealed the importance of gut microbiota in the control of these diseases. The composition or diversity of these microbiota is different between patients with these conditions and healthy controls, and administration of probiotics or prebiotics has been shown effective in the treatment of these diseases. Gut microbiota may affect distant organs through mechanisms that include regulating the absorption of nutrients and/or the production of microbial metabolites, regulating and interacting with the systemic immune system, and translocating bacteria/bacterial products through disrupted mucosal barriers. Thus, the gut microbiota may be important regulators in the development of diseases that affect ADL. Although adequate exercise and proper diet are important for preventing these diseases, their combination with interventions that manipulate the composition and/or diversity of gut microbiota could be a promising strategy for maintaining health condition and preserving ADL. This review thus summarizes current understanding of the role of gut microbiota in the development or prevention of diseases closely associated with the maintenance of ADL.

Neuroinflammation in mouse models of Alzheimer's disease

Alzheimer's disease (AD) is the most common type of neurocognitive disorder. Although both amyloid β peptide deposition and neurofibrillary tangle formation in the AD brain have been established as pathological hallmarks of the disease, many other factors contribute in a complex manner to the pathogenesis of AD before clinical symptoms of the disease become apparent. Longitudinal pathophysiological processes cause patients' brains to exist in a state of chronic neuroinflammation, with glial cells acting as key regulators of the neuroinflammatory state. However, the detailed molecular and cellular mechanisms of glial function underlying AD pathogenesis remain elusive. Furthermore, recent studies have shown that peripheral inflammatory conditions affect glial cells in the brain through a process of neuroimmune communication. Such disease complexities make it difficult for the pathogenesis of AD to be understood, and impede the development of effective therapeutic strategies to combat the disease. Relevant AD animal models are thus likely to serve as a key resource to overcome many of these issues. Furthermore, as the pathogenesis of AD might be linked to conditions both within the brain as well as peripherally, it might become necessary for AD to be studied as a whole-body disorder. The present review aimed to summarize insights regarding current AD research, and share perspectives for understanding glial function in the context of the pathogenesis of AD.

Induction and modulation of genotoxicity by the bacteriome in mammals

The living environment is a multilevel physical and chemical xenobiotic complex with potentially mutagenic effects and health risks. In addition to inorganic exposures, all terrestrial and aquatic living forms interact with microbiota as selectively established communities of bacteria, viruses and fungi. Along these lines, the human organism should then be considered a "meta-organism" with complex dynamics of interaction between the environment and microbiome. Bacterial communities within the microbiome, bacteriome, by its mass, symbiotic or competitive position and composition are in a fragile balance with the host organisms and have a crucial impact on their homeostasis. Bacteriome taxonomic composition is modulated by age, sex and host genetic profile and may be changed by adverse environmental exposures and life style factors such as diet or drug intake. A changed and/or misbalanced bacteriome has genotoxic potential with significant impact on the pathogenesis of acute, chronic and neoplastic diseases in the host organism. Bacteria may produce genotoxins, express a variety of pathways in which they generate free radicals or affect DNA repair causing genome damage, cell cycle arrest and apoptosis, modulate immune response and launch carcinogenesis in the host organism. Future investigations should focus on the interplay between exposure to xenobiotics and bacteriome composition, immunomodulation caused by misbalanced bacteriome, impact of the environment on bacteriome composition in children and its lifelong effect on health risks.