Immunity orchestrates a bridge in gut-brain axis of neurodegenerative diseases

Gut microbiota regulate stress resistance by influencing microglia-neuron interactions in the hippocampus

Communication among the brain, gut and microbiota in the gut is known to affect the susceptibility to stress, but the mechanisms involved are unclear. Here we demonstrated that stress resistance in mice was associated with more abundant Lactobacillus and Akkermansia in the gut, but less abundant Bacteroides, Alloprevotella, Helicobacter, Lachnoclostridium, Blautia, Roseburia, Colidextibacter and Lachnospiraceae NK4A136. Stress-sensitive animals showed higher permeability and stronger immune responses in their colon, as well as higher levels of pro-inflammatory cytokines in serum. Their hippocampus also showed more extensive microglial activation, abnormal interactions between microglia and neurons, and lower synaptic plasticity. Transplanting fecal microbiota from stress-sensitive mice into naïve ones perturbed microglia-neuron interactions and impaired synaptic plasticity in the hippocampus, translating to more depression-like behavior after stress exposure. Conversely, transplanting fecal microbiota from stress-resistant mice into naïve ones protected microglia from activation and preserved synaptic plasticity in the hippocampus, leading to less depression-like behavior after stress exposure. These results suggested that gut microbiota may influence resilience to chronic psychological stress by regulating microglia-neuron interactions in the hippocampus.

MicrobeTCM: A comprehensive platform for the interactions of microbiota and traditional Chinese medicine

Thanks to the advancements in bioinformatics, drugs, and other interventions that modulate microbes to treat diseases have been emerging continuously. In recent years, an increasing number of databases related to traditional Chinese medicine (TCM) or gut microbes have been established. However, a database combining the two has not yet been developed. To accelerate TCM research and address the traditional medicine and micro ecological system connection between short board, we have developed the most comprehensive micro-ecological database of TCM. This initiative includes the standardization of the following advantages: (1) A repeatable process achieved through the standardization of a retrieval strategy to identify literature. This involved identifying 419 experiment articles from PubMed and six authoritative databases; (2) High-quality data integration achieved through double-entry extraction of literature, mitigating uncertainties associated with natural language extraction; (3) Implementation of a similar strategy aiding in the prediction of mechanisms of action. Leveraging drug similarity, target entity similarity, and known drug-target entity association, our platform enables the prediction of the effects of a new herb or acupoint formulas using the existing data. In total, MicrobeTCM includes 171 diseases, 725 microbes, 1468 herb-formulas, 1032 herbs, 15780 chemical compositions, 35 acupoint-formulas, and 77 acupoints. For further exploration, please visit https://www.microbetcm.com.

Effects of Different Heat Treatments on Yak Milk Proteins on Intestinal Microbiota and Metabolism

Dairy products are susceptible to modifications in protein oxidation during heat processing, which can lead to changes in protein function, subsequently affecting intestinal health. Despite being a unique nutritional source, yak milk has not been thoroughly examined for the effects of its oxidized proteins on intestinal microbiota and metabolism. Hence, this study employed different heat treatment methods (low-temperature pasteurization, high-temperature pasteurization, and high-temperature sterilization) to induce oxidation in yak milk proteins. The study then assessed the degree of oxidation in these proteins and utilized mice as research subjects. Using metagenomics and metabolomics methods, this study examined the structure of intestinal microbial communities and metabolic products in mice consuming oxidized yak milk. The results showed a decrease in carbonyl and total thiol contents of yak milk proteins after different heat treatments, indicating that heat treatment causes oxidation in yak milk proteins. Metagenomic analysis of mouse intestinal microbiota revealed significant changes in 66 genera. In the high-temperature sterilization group (H), key differential genera included Verrucomicrobiales, Verrucomicrobiae, Akkermansiaceae, and 28 others. The high-temperature pasteurization group (M) mainly consisted of Latilactobacillus, Bacillus, and Romboutsia. The low-temperature pasteurization group (L) primarily comprised of Faecalibacterium, Chaetomium, Paenibacillaceae, Eggerthella, Sordariales, and 33 others. Functionally, compared to the control group (C), the H group upregulated translation and energy metabolism functions, the L group the M group significantly upregulated metabolism of other amino acids, translation, and cell replication and repair functions. Based on metabolomic analysis, differential changes in mouse metabolites could affect multiple metabolic pathways in the body. The most significantly affected metabolic pathways were phenylalanine metabolism, vitamin B6 metabolism, steroid hormone biosynthesis, and pantothenate and CoA biosynthesis. The changes were similar to the functional pathway analysis of mouse metagenomics, affecting amino acid and energy metabolism in mice. In summary, moderate oxidation of yak milk proteins exhibits a positive effect on mouse intestinal microbiota and metabolism. In conclusion, yak milk has a positive effect on mouse intestinal microflora and metabolism, and this study provides a scientific basis for optimizing dairy processing technology and further developing and applying yak milk.

Naringenin confers protection against experimental autoimmune encephalomyelitis through modulating the gut-brain axis: A multiomics analysis

Multiple sclerosis (MS) is a disease of the central nervous system that involves the immune system attacking the protective covering of nerve fibers. This disease can be influenced by both environmental and genetic factors. Evidence has highlighted the critical role of the intestinal microbiota in MS and its animal model, experimental autoimmune encephalomyelitis (EAE). The composition of gut microflora is mainly determined by dietary components, which, in turn, modulate host homeostasis. A diet rich in naringenin at 0.5% can effectively mitigate the severity of EAE in mice. However, there is little direct data on the impact of naringenin at optimal doses on EAE development, as well as its intestinal microbiota and metabolites. Our study revealed that 2.0% naringenin resulted in the lowest clinical score and pathological changes in EAE mice, and altered the gene expression profiles associated with inflammation and immunity in spinal cord tissue. We then used untargeted metabolomics and 16S rRNA gene sequences to identify metabolites and intestinal microbiota, respectively. Naringenin supplementation enriched gut microbiota in EAE mice, including increasing the abundance of Paraprevotellaceae and Comamonadaceae, while decreasing the abundance of Deltaproteobacteria, RF39, and Desulfovibrionaceae. Furthermore, the changes in gut microbiota affected the production of metabolites in the feces and brain, suggesting a role in regulating the gut-brain axis. Finally, we conducted a fecal transplantation experiment to validate that gut microbiota partly mediates the effect of naringenin on EAE alleviation. In conclusion, naringenin has potential immunomodulatory effects that are influenced to some extent by the gut microbiome.

Impact of Donepezil Supplementation on Alzheimer's Disease-like Pathology and Gut Microbiome in APP/PS1 Mice

Based on published information, the occurrence and development of Alzheimer's disease (AD) are potentially related to gut microbiota changes. Donepezil hydrochloride (DH), which enhances cholinergic activity by blocking acetylcholinesterase (AChE), is one of the first-line drugs for AD treatment approved by the Food and Drug Administration (FDA) of the USA. However, the potential link between the effects of DH on the pathophysiological processes of AD and the gut microbiota remains unclear. In this study, pathological changes in the brain and colon, the activities of superoxide dismutase (SOD) and AChE, and changes in intestinal flora were observed. The results showed that Aβ deposition in the prefrontal cortex and hippocampus of AD mice was significantly decreased, while colonic inflammation was significantly alleviated by DH treatment. Concomitantly, SOD activity was significantly improved, while AChE was significantly reduced after DH administration. In addition, the gut microbiota community composition of AD mice was significantly altered after DH treatment. The relative abundance of Akkermansia in the AD group was 54.8% higher than that in the N group. The relative abundance of Akkermansia was increased by 18.3% and 53.8% in the AD_G group and the N_G group, respectively. Interestingly, Akkermansia showed a potential predictive value and might be a biomarker for AD. Molecular docking revealed the binding mode and major forces between DH and membrane proteins of Akkermansia. The overall results suggest a novel therapeutic mechanism for treating AD and highlight the critical role of gut microbiota in AD pathology.

Fecal microbiota transplantation holds the secret to youth

Aging shows itself not just at the cellular level, with shortened telomeres and cell cycle arrest, but also at the organ and organismal level, with diminished brainpower, dry eyes, intestinal inflammation, muscular atrophy, wrinkles, etc. When the gut microbiota, often called the "virtual organ of the host," fails to function normally, it can lead to a cascade of health problems including, but not limited to, inflammatory bowel disease, obesity, metabolic liver disease, type II diabetes, cardiovascular disease, cancer, and even neurological disorders. An effective strategy for restoring healthy gut bacteria is fecal microbiota transplantation (FMT). It can reverse the effects of aging on the digestive system, the brain, and the vision by transplanting the functional bacteria found in the excrement of healthy individuals into the gut tracts of patients. This paves the way for future research into using the microbiome as a therapeutic target for disorders associated with aging.