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

Emerging epigenetic dynamics in gut-microglia brain axis: experimental and clinical implications for accelerated brain aging in schizophrenia

Brain aging, which involves a progressive loss of neuronal functions, has been reported to be premature in probands affected by schizophrenia (SCZ). Evidence shows that SCZ and accelerated aging are linked to changes in epigenetic clocks. Recent cross-sectional magnetic resonance imaging analyses have uncovered reduced brain reserves and connectivity in patients with SCZ compared to typically aging individuals. These data may indicate early abnormalities of neuronal function following cyto-architectural alterations in SCZ. The current mechanistic knowledge on brain aging, epigenetic changes, and their neuropsychiatric disease association remains incomplete. With this review, we explore and summarize evidence that the dynamics of gut-resident bacteria can modulate molecular brain function and contribute to age-related neurodegenerative disorders. It is known that environmental factors such as mode of birth, dietary habits, stress, pollution, and infections can modulate the microbiota system to regulate intrinsic neuronal activity and brain reserves through the vagus nerve and enteric nervous system. Microbiota-derived molecules can trigger continuous activation of the microglial sensome, groups of receptors and proteins that permit microglia to remodel the brain neurochemistry based on complex environmental activities. This remodeling causes aberrant brain plasticity as early as fetal developmental stages, and after the onset of first-episode psychosis. In the central nervous system, microglia, the resident immune surveillance cells, are involved in neurogenesis, phagocytosis of synapses and neurological dysfunction. Here, we review recent emerging experimental and clinical evidence regarding the gut-brain microglia axis involvement in SCZ pathology and etiology, the hypothesis of brain reserve and accelerated aging induced by dietary habits, stress, pollution, infections, and other factors. We also include in our review the possibilities and consequences of gut dysbiosis activities on microglial function and dysfunction, together with the effects of antipsychotics on the gut microbiome: therapeutic and adverse effects, role of fecal microbiota transplant and psychobiotics on microglial sensomes, brain reserves and SCZ-derived accelerated aging. We end the review with suggestions that may be applicable to the clinical setting. For example, we propose that psychobiotics might contribute to antipsychotic-induced therapeutic benefits or adverse effects, as well as reduce the aging process through the gut-brain microglia axis. Overall, we hope that this review will help increase the understanding of SCZ pathogenesis as related to chronobiology and the gut microbiome, as well as reveal new concepts that will serve as novel treatment targets for SCZ.

Ginseng under forest exerts stronger anti-aging effects compared to garden ginseng probably via regulating PI3K/AKT/mTOR pathway, SIRT1/NF-κB pathway and intestinal flora

BACKGROUND

Ginseng is deemed to be an effective anti-aging therapy. Evidence for differences in representative active ingredients and anti-aging effects between garden ginseng (GG) and ginseng under forest (FG) is insufficient.

PURPOSE

The study was designed to systematically analyze the differences in the mechanistic protective effects of GG and FG on aging mice based on their compositional differences.

METHODS

The chemical ingredients in GG and FG were first determined. In vivo, D-galactose-induced aging mice were orally administered GG or FG (400 mg/kg/day) for 6 weeks. Behavioral parameters of mice were measured by the radial 8-arm maze, and the changes in body weight and organ indices were recorded. Blood, brain tissue, and feces were collected for biochemical analysis, histopathological staining, Western blotting, and 16S rDNA intestinal flora sequencing, respectively.

RESULTS

The absolute contents of total ginsenosides, polyphenols, crude polysaccharides, starch, and protein in GG were 0.71, 0.68, 1.15, 2.27, and 1.08 folds higher than those in FG, respectively; while FG exhibited a higher relative abundance of representative active ingredients (total ginsenosides, polyphenols, crude polysaccharides, and protein) but lower relative content of starch than GG. GG and FG improved hippocampal lesions and poor weight gain, organ indices, and behavioral indices, and prevented excessive oxidative stress and acetylcholinesterase activity in aging mice. What's more, GG and FG treatment ameliorated excessive apoptosis and inflammatory reaction in the aging brain by modulating apoptosis-related proteins, PI3K/AKT/mTOR pathway, and SIRT1/NF-κB pathway. GG and FG also restored the diversity and structure of gut microbiota, up-regulated the relative abundance of beneficial bacteria (e.g., Lactobacillus), and tended to exert key anti-aging effects via the microbiota-gut-brain axis. Notably, in vivo experiments confirmed that FG had a stronger anti-aging activity than GG.

CONCLUSION

FG exerts a more powerful anti-aging effect than GG by regulating oxidative stress, apoptosis, inflammation, and the microbe-gut-brain axis, possibly relying on the higher relative abundance of representative active ingredients (total ginsenosides, polyphenols, crude polysaccharides, and protein) in FG.

Chitosan-modified Phellinus igniarius polysaccharide PLGA nanoparticles ameliorated inflammatory bowel disease

In many clinical studies, prebiotics have been used as adjuvant therapy for inflammatory bowel disease (IBD). Phellinus igniarius polysaccharide (PIP) possesses great anti-inflammatory and prebiotic activities. Herein, we developed an orally deliverable PIP-loaded chitosan-modified PLGA nanomedicine (CS-PIPP) to investigate its anti-inflammatory effect in vitro and in vivo. Dextran sodium sulfate (DSS)-induced colitis model was established to evaluate the preventive effect of CS-PIPP on IBD. This study characterized that CS-PIPP had a size of 288.7 ± 5.49 nm, positive zeta potential, and showed good stability over four weeks. The in-vitro study suggested that CS-PIPP had enhanced phagocytosis by macrophages, which could further significantly inhibit M1-like macrophages phenotype and regulate lipopolysaccharide (LPS)-induced inflammatory cytokines. The in-vivo study revealed that CS-PIPP prominently prevented intestinal inflammatory damage and protected the integrity of the intestinal barrier. Moreover, CS-PIPP increased the contents of short-chain fatty acids (SCFAs) and positively regulated the gut microbiota. Specifically, CS-PIPP reduced enteropathogenic microorganisms while increasing the beneficial microbiota, including Lactobacillus and Akkermansia, which revealed the potential of CS-PIPP as prebiotics. Generally, CS-PIPP promoted the anti-inflammatory effect of PIP, so it could be regarded as a novel and potent nanoformulation to treat IBD.

Microbiome breeding: conceptual and practical issues

Microbiome breeding is a new artificial selection technique that seeks to change the genetic composition of microbiomes in order to benefit plant or animal hosts. Recent experimental and theoretical analyses have shown that microbiome breeding is possible whenever microbiome-encoded genetic factors affect host traits (e.g., health) and microbiomes are transmissible between hosts with sufficient fidelity, such as during natural microbiome transmission between individuals of social animals, or during experimental microbiome transplanting between plants. To address misunderstandings that stymie microbiome-breeding programs, we (i) clarify and visualize the corresponding elements of microbiome selection and standard selection; (ii) elucidate the eco-evolutionary processes underlying microbiome selection within a quantitative genetic framework to summarize practical guidelines that optimize microbiome breeding; and (iii) characterize the kinds of host species most amenable to microbiome breeding.

Gut microbiome-immune system interaction in reptiles

Reptiles are ectothermic amniotes in a world dominated by endotherms. Reptiles originated more than 300 million years ago and they often dwell in polluted environments which may expose them to pathogenic micro-organisms, radiation and/or heavy metals. Reptiles also possess greater longevity and may live much longer than similar-sized land mammals, for example, turtles, tortoises, crocodiles and tuatara are long-lived reptiles living up to 100 years or more. Many recent studies have emphasized the pivotal role of the gut microbiome on its host; thus, we postulated that reptilian gut microbiome and/or its metabolites and the interplay with their robust immune system may contribute to their longevity and overall hardiness. Herein, we discuss the composition of the reptilian gut microbiome, immune system-gut microbiome cross-talk, antimicrobial peptides, reptilian resistance to infectious diseases and cancer, ageing, as well the current knowledge of the genome and epigenome of these remarkable species. Preliminary studies have demonstrated that microbial gut flora of reptiles such as crocodiles, tortoises, water monitor lizard and python exhibit remarkable anticancer and antibacterial properties, as well as comprise novel gut bacterial metabolites and antimicrobial peptides. The underlying mechanisms between the gut microbiome and the immune system may hold clues to developing new therapies overall for health, and possible extrapolation to exploit the ancient defence systems of reptiles for Homo sapiens benefit.

Longevity, cellular senescence and the gut microbiome: lessons to be learned from crocodiles

Crocodiles are flourishing large-bodied ectotherms in a world dominated by endotherms. They survived the Cretaceous extinction event, that eradicated the dinosaurs who are thought to be their ancestral hosts. Crocodiles reside in polluted environments; and often inhabit water which contains heavy metals; frequent exposure to radiation; feed on rotten meat and considered as one of the hardy species that has successfully survived on this planet for millions of years. Another capability that crocodiles possess is their longevity. Crocodiles live much longer than similar-sized land mammals, sometimes living up to 100 years. But how do they withstand such harsh conditions that are detrimental to Homo sapiens? Given the importance of gut microbiome on its' host physiology, we postulate that the crocodile gut microbiome and/or its' metabolites produce substances contributing to their "hardiness" and longevity. Thus, we accomplished literature search in PubMed, Web of Science and Google Scholar and herein, we discuss the composition of the crocodile gut microbiome, longevity and cellular senescence in crocodiles, their resistance to infectious diseases and cancer, and our current knowledge of the genome and epigenome of these remarkable species. Furthermore, preliminary studies that demonstrate the remarkable properties of crocodile gut microbial flora are discussed. Given the profound role of the gut microbiome in the health of its' host, it is likely that the crocodile gut microbiome and its' metabolites may be contributing to their extended life expectancy and elucidating the underlying mechanisms and properties of these metabolites may hold clues to developing new treatments for age-related diseases for the benefit of Homo sapiens.

A Tale of Two Diseases: Exploring Mechanisms Linking Diabetes Mellitus with Alzheimer's Disease

Dementias, including the type associated with Alzheimer's disease (AD), are on the rise worldwide. Similarly, type 2 diabetes mellitus (T2DM) is one of the most prevalent chronic diseases globally. Although mechanisms and treatments are well-established for T2DM, there remains much to be discovered. Recent research efforts have further investigated factors involved in the etiology of AD. Previously perceived to be unrelated diseases, commonalities between T2DM and AD have more recently been observed. As a result, AD has been labeled as "type 3 diabetes". In this review, we detail the shared processes that contribute to these two diseases. Insulin resistance, the main component of the pathogenesis of T2DM, is also present in AD, causing impaired brain glucose metabolism, neurodegeneration, and cognitive impairment. Dysregulation of insulin receptors and components of the insulin signaling pathway, including protein kinase B, glycogen synthase kinase 3β, and mammalian target of rapamycin are reported in both diseases. T2DM and AD also show evidence of inflammation, oxidative stress, mitochondrial dysfunction, advanced glycation end products, and amyloid deposition. The impact that changes in neurovascular structure and genetics have on the development of these conditions is also being examined. With the discovery of factors contributing to AD, innovative treatment approaches are being explored. Investigators are evaluating the efficacy of various T2DM medications for possible use in AD, including but not limited to glucagon-like peptide-1 receptor agonists, and peroxisome proliferator-activated receptor-gamma agonists. Furthermore, there are 136 active trials involving 121 therapeutic agents targeting novel AD biomarkers. With these efforts, we are one step closer to alleviating the ravaging impact of AD on our communities.