Lactobacillus gasseri NK109 and Its Supplement Alleviate Cognitive Impairment in Mice by Modulating NF-κB Activation, BDNF Expression, and Gut Microbiota Composition

Heat-Processed Soybean Germ Extract and Lactobacillus gasseri NK109 Supplementation Reduce LPS-Induced Cognitive Impairment and Colitis in Mice

Soybean alleviates cognitive impairment. In our preparatory experiment, we found that dry-heat (90 °C for 30 min)-processed soybean embryo ethanol extract (hSE) most potently suppressed lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α expression in BV2 cells among dry-heat-, steaming-, and oil exclusion-processed soybean embryo ethanol extracts (SEs). Heat processing increased the absorbable soyasaponin Bb content of SE. Therefore, we investigated whether hSE and its supplement could mitigate LPS-impaired cognitive function in mice. Among dry-heat-, steaming-, and oil exclusion-processed SEs, hSE mitigated LPS-impaired cognitive function more than parental SE. hSE potently upregulated LPS-suppressed brain-derived neurotropic factor (BDNF) expression in the hippocampus, while LPS-induced TNF-α and IL-1β expression in the hippocampus and colon were downregulated. Lactobacillus gasseri NK109 additively increased the cognitive function-enhancing activity of hSE in mice with LPS-induced cognitive impairment as follows: the hSE and NK109 mix potently increased cognitive function and hippocampal BDNF expression and BDNF-positive neuron cell numbers and decreased TNF-α expression and NF-κB-positive cell numbers in the hippocampus and colon. These findings suggest that hSE and its supplement may decrease colitis and neuroinflammation by suppressing NF-κB activation and inducing BDNF expression, resulting in the attenuation of cognitive impairment.

Pseudostellaria heterophylla polysaccharide mitigates Alzheimer's-like pathology via regulating the microbiota-gut-brain axis in 5 × FAD mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by neuroinflammation, for which gut dysbiosis may be implicated. Our previous study showed that treatment with Pseudostellaria heterophylla aqueous extract and one of its cyclopeptides, heterophyllin B, attenuate memory deficits via immunomodulation and neurite regeneration. However, whether Pseudostellaria heterophylla polysaccharide (PH-PS) exerts neuroprotective effects against AD and its underlying mechanisms remain unclear. The infrared spectrum, molecular weight, and carbohydrate composition of the PH-PS were determined. The results showed that PH-PS (Mw 8.771 kDa) was composed of glucose (57.78 %), galactose (41.52 %), and arabinose (0.70 %). PH-PS treatment ameliorated learning and spatial memory deficits, reduced amyloid β build-up, and suppressed reactive glia and astrocytes in 5 × FAD mice. 16S rRNA sequencing further showed that PH-PS remodelled the intestinal flora composition by promoting probiotic microbiota, such as Lactobacillus, Muribaculum, Monoglobus, and [Eubacterium]_siraeum_group, and suppressing inflammation-related UCG-009 and Blautia. Additionally, PH-PS restored intestinal barrier function; ameliorated peripheral inflammation by reducing the secretion of inflammatory cytokines, thereby converting M1 microglia and A1 astrocyte toward beneficial M2 and A2 phenotypes; and contributed to Aβ plaques clearance by upregulation of insulin degradation enzyme and neprilysin. Collectively, our findings demonstrate that PH-PS may prevent the progression of AD via modulation of the gut microbiota and regulation of glial polarisation, which could provide evidence to design a potential diet therapy for preventing or curing AD.

Gut microbiota in centenarians: A potential metabolic and aging regulator in the study of extreme longevity

Centenarians, those aged 100 years or older, are considered the most successful biological aging model in humans. This population is commonly characterized by a low prevalence of chronic diseases, with favorable maintenance of functionality and independence, thus determining a health phenotype of successful aging. There are many factors usually associated with extreme longevity: genetics, lifestyles, diet, among others. However, it is most likely a multifactorial condition where protective factors contribute individually to some extent. The gut microbiota (GM) has emerged as a potential factor associated with the establishment of a favorable health phenotype that allows for extreme longevity, as seen in centenarians. To understand the possible impact generated by the GM, its changes, and the probable causes for successful aging, the aim of this review was to synthesize evidence on the role of the GM as a potential protective factor for achieving extreme longevity, using its relationship with centenarians.

Radix Bupleuri aqueous extract attenuates MK801-induced schizophrenia-like symptoms in mice: Participation of intestinal flora

Schizophrenia (SCZ) is a psychotic mental disorder characterized by cognitive, behavioral, and social impairments. However, current pharmacological treatment regimens are subpar in terms of effectiveness. This study aimed to investigate the function of Radix Bupleuri aqueous extract in SCZ in mouse models. The SCZ mouse model was established by MK-801 injection and feeding of Radix Bupleuri aqueous extract or combined antibiotics. Radix Bupleuri aqueous extract significantly improved the aberrant behaviors and neuronal damage in SCZ mice, upregulated SYP and PSD-95 expression and BDNF levels in hippocampal homogenates, down-regulated DA and 5-HT levels, and suppressed microglial activation in SCZ mice. Moreover, Radix Bupleuri aqueous extract improved the integrity of the intestinal tract barrier. The 16 S rRNA sequencing of feces showed that Radix Bupleuri extract modulated the composition of gut flora. Lactobacillus abundance was decreased in SCZ mice and reversed by Radix Bupleuri aqueous extract administration which exhibited a significant negative correlation with IL-6, IL-1β, DA, and 5-HT, and a significant positive correlation with BDNF levels in hippocampal tissues. The abundance of Parabacteroides and Alloprevotella was increased in SCZ mice. It was reversed by Radix Bupleuri aqueous extract administration, which exhibited a positive correlation with IL-6, IL-1β, and 5-HT and a negative correlation with BDNF. In conclusion, Radix Bupleuri aqueous extract attenuates the inflammatory response in hippocampal tissues and modulates neurotransmitter levels, exerting its neuroprotective effect in SCZ. Meanwhile, the alteration of intestinal flora may be involved in this process, which is expected to be an underlying therapeutic option in treating SCZ.

Causal relationship between gut microflora and dementia: a Mendelian randomization study

Background

Numerous pertinent investigations have demonstrated a correlation between gut microflora (GM) and the occurrence of dementia. However, a causal connection between GM and dementia and its subtypes has not yet been clarified.

Objective

To explore the causal association between GM and dementia, including its subtypes, a two-sample Mendelian randomization (TSMR) analysis was used.

Methods

Our data comes from the Genome-Wide Association Study (GWAS). The principal approach employed for the Mendelian randomization study was the inverse-variance weighted method, supplemented by four methods: MR-Egger, weighted median, simple mode, and weighted mode. This was followed by Cochrane's Q test, MR-Egger intercept test, MR-PRESSO global test, and leave-one-out as sensitivity analysis validation.

Results

Twenty-one GMs associated with any dementia, Alzheimer's disease, vascular dementia, Lewy body dementia, Parkinson's disease, and dementia under other disease classifications were derived from the analysis, and 21 passed sensitivity tests.

Conclusion

We confirmed the causal relationship between GM and dementia and its subtypes, derived specific flora associated with increased or decreased risk of dementia, and provided new ideas for preventive, diagnostic, and therapeutic interventions for dementia mediated by gut microbiota.

Alleviation of Cognitive Impairment-like Behaviors, Neuroinflammation, Colitis, and Gut Dysbiosis in 5xFAD Transgenic and Aged Mice by Lactobacillus mucosae and Bifidobacterium longum

Neuropsychiatric disorders including Alzheimer's disease (AD) may cause gut inflammation and dysbiosis. Gut inflammation-suppressing probiotics alleviate neuropsychiatric disorders. Herein, to understand whether anti-inflammatory probiotics Lactobacillus mucosae NK41 and Bifidobacterium longum NK46, which suppressed tumor necrosis factor (TNF)-α expression in lipopolysaccharide (LPS)-stimulated macrophages, could alleviate cognitive impairment, we first examined their effects on cognitive function, gut inflammation, and gut microbiota composition in 5xFAD-transgenic mice. Oral administration of NK41 or NK46 decreased cognitive impairment-like behaviors, hippocampal amyloid-β (Aβ), TNF-α and interleukin (IL)-1β expression, hippocampal NF-κB+Iba1+ cell population, and Aβ accumulation, while hippocampal brain-derived neurotropic factor (BDNF) and IL-10 expression and BDNF+NeuN+ cell population increased. They also decreased TNF-α and IL-1β expression and NF-κB+CD11c+ cell population in the colon. They also reduced fecal and blood LPS levels and gut Proteobacteria and Verrucomicrobia populations (including Akkkermansiaceae), which are positively associated with hippocampal TNF-α and fecal LPS levels and negatively correlated with hippocampal BDNF level. However, they increased Odoribactericeae, which positively correlated with BDNF expression level and TNF-α to IL-10 expression ratio. The combination of NK41 and NK46 (4:1, NKc), which potently inhibited TNF-α expression in LPS-stimulated macrophages, additively alleviated cognitive impairment-like behaviors in 5xFAD-transgenic or aged mice. NKc increased hippocampal BDNF+NeuN+ cell population and BDNF expression in 5xFAD-transgenic or aged mice, while hippocampal TNF-α and IL-1β expression decreased. NKc also decreased TNF-α and IL-1β expression in the colon and LPS levels in the blood and feces. These findings suggest that gut bacteria and its product LPS may be closely connected with occurrence of cognitive impairment and neuroinflammation and the combination of NK41 and NK46 can additively alleviate cognitive impairment and neuroinflammation by inducing NF-κB-suppressed BDNF expression and suppressing LPS-producing gut bacteria.