Neuroprotection of Fasting Mimicking Diet on MPTP-Induced Parkinson's Disease Mice via Gut Microbiota and Metabolites

Cannabidiol (CBD) facilitates cocaine extinction and ameliorates cocaine-induced changes to the gut microbiome in male C57BL/6JArc mice

Cocaine use disorder (CUD) is a global health problem with no approved medications. One potential treatment target is the gut microbiome, but it is unknown if cocaine induces long-lasting effects on gut microbes. A novel therapeutic candidate for CUD, cannabidiol (CBD), can improve gut function in rodent models. It is possible that protective effects of CBD against cocaine use are mediated by improving gut health. We examined this question in this experiment. Cocaine conditioned place preference (CPP) was conducted in adult male C57BL/6JArc mice. Mice were treated with vehicle or 20 mg/kg CBD prior to all cocaine CPP sessions (N = 11-13/group). Mice were tested drug free 1, 14 and 28 days after cessation of cocaine and CBD treatment. Fecal samples were collected prior to drug treatment and after each test session. Gut microbiome analyses were conducted using 16 s rRNA sequencing and correlated with behavioural parameters. We found a persistent preference for a cocaine-environment in mice, and long-lasting changes to gut microbe alpha diversity. Cocaine caused persistent changes to beta diversity which lasted for 4 weeks. CBD treatment reduced cocaine-environment preference during abstinence from cocaine and returned gut beta diversity measures to control levels. CBD treatment increased the relative abundance of Firmicutes phyla and Oscillospira genus, but decreased Bacteroidetes phyla and Bacteroides acidifaciens species. Preference score in cocaine-treated mice was positively correlated with abundance of Actinobacteria, whereas in mice treated with CBD and cocaine, the preference score was negatively correlated with Tenericutes abundance. Here we show that CBD facilitates cocaine extinction memory and reverses persistent cocaine-induced changes to gut microbe diversity. Furthermore, CBD increases the abundance of gut microbes which have anti-inflammatory properties. This suggests that CBD may act via the gut to reduce the memory of cocaine reward. Our data suggest that improving gut health and using CBD could limit cocaine abuse.

Crosstalk between gut-brain axis: unveiling the mysteries of gut ROS in progression of Parkinson's disease

"Path to a good mood lies through the gut." This statement seems to imply that it has long been believed that the gut is connected with the brain. Research has shown that eating food activates the reward system and releases dopamine (DA), establishing a link between the peripheral and central nervous system. At the same time, researchers also trust that the gut is involved in the onset of many diseases, including Parkinson's disease (PD), in which gastrointestinal dysfunction is considered a prevalent symptom. Reports suggest that PD starts from the gut and reaches the brain via the vagus nerve. Recent studies have revealed an intriguing interaction between the gut and brain, which links gut dysbiosis to the etiology of PD. This review aims to explore the mechanistic pathway how reactive oxygen species (ROS) generation in the gut affects the makeup and operation of the dopamine circuitry in the brain. Our primary concern is ROS generation in the gut, which disrupts the gut microbiome (GM), causing α-synuclein accumulation and inflammation. This trio contributes to the loss of DA neurons in the brain, resulting in PD development. This review also compiles pre-clinical and clinical studies on antioxidants, demonstrating that antioxidants reduce ROS and increase DA levels. Collectively, the study highlights the necessity of comprehending the gut-brain axis for unraveling the riddles of PD pathogenesis and considering new therapeutic approaches.

Gut-directed therapy in Parkinson's disease

Parkinson's disease (PD) is a common and slow-progressing neurodegenerative disorder characterized by motor and non-motor symptoms, including gastrointestinal (GI) dysfunctions. Over the last years, the microbiota-gut-brain (MGB) axis is emerging as a bacterial-neuro-immune ascending pathway that contributes to the progression of PD. Indeed, PD patients are characterized by changes in gut microbiota composition, alterations of intestinal epithelial barrier (IEB) and enteric neurogenic/inflammatory responses that, besides determining intestinal disturbances, contribute to brain pathology. In this context, despite the causal relationship between gut dysbiosis, impaired MGB axis and PD remains to be elucidated, emerging evidence shows that MGB axis modulation can represent a suitable therapeutical strategy for the treatment of PD. This review provides an overview of the available knowledge about the beneficial effects of gut-directed therapies, including dietary interventions, prebiotics, probiotics, synbiotics and fecal microbiota transplantation (FMT), in both PD patients and animal models. In this context, particular attention has been devoted to the mechanisms by which the modulation of MGB axis could halt or slow down PD pathology and, most importantly, how these approaches can be included in the clinical practice.

The regulatory effect of intermittent fasting on inflammasome activation in health and disease

Intermittent fasting (IF), one of the most popular diets, can regulate inflammation and promote health; however, the detailed molecular mechanisms are not fully understood. The present review aims to provide an overview of recent preclinical and clinical studies that have examined the effect of IF on inflammasome signaling, and to discuss the translational gap between preclinical and clinical studies. Three databases (PubMed, Web of Science, and Embase) were searched to identify all relevant preclinical and clinical studies up to October 30, 2022. A total of 1544 studies were identified through the database searches, and 29 preclinical and 10 clinical studies were included. Twenty-three of the 29 preclinical studies reported that IF treatment could reduce inflammasome activation in neurological diseases, metabolic and cardiovascular diseases, immune and inflammatory diseases, gastrointestinal diseases, and pulmonary diseases, and 7 of the 10 clinical studies demonstrated reduced inflammasome activation after IF intervention in both healthy and obese participants. Among various IF regimens, time-restricted eating seemed to be the most effective one in terms of inflammasome regulation, and the efficacy of IF might increase over time. This review highlights the regulatory effect of IF on inflammasome activation in health and disease. Future studies using different IF regimens, in various populations, are needed in order to evaluate its potential to be used alone or as an adjunct therapy in humans to improve health and counteract diseases.

Eating away cancer: the potential of diet and the microbiome for shaping immunotherapy outcome

The gut microbiome (GMB) plays a substantial role in human health and disease. From affecting gut barrier integrity to promoting immune cell differentiation, the GMB is capable of shaping host immunity and thus oncogenesis and anti-cancer therapeutic response, particularly with immunotherapy. Dietary patterns and components are key determinants of GMB composition, supporting the investigation of the diet-microbiome-immunity axis as a potential avenue to enhance immunotherapy response in cancer patients. As such, this review will discuss the role of the GMB and diet on anti-cancer immunity. We demonstrate that diet affects anti-cancer immunity through both GMB-independent and GMB-mediated mechanisms, and that different diet patterns mold the GMB's functional and taxonomic composition in distinctive ways. Dietary modulation therefore shows promise as an intervention for improving cancer outcome; however, further and more extensive research in human cancer populations is needed.

The interplay between gut microbiota and the brain-gut axis in Parkinson's disease treatment

This study delves into the pivotal role of the gut microbiota and the brain-gut axis in Parkinson's Disease (PD), a neurodegenerative disorder with significant motor and non-motor implications. It posits that disruptions in gut microbiota-dysbiosis-and alterations in the brain-gut axis contribute to PD's pathogenesis. Our findings highlight the potential of the gastrointestinal system's early involvement in PD, suggested by the precedence of gastrointestinal symptoms before motor symptoms emerge. This observation implies a possible gut-originated disease pathway. The analysis demonstrates that dysbiosis in PD patients leads to increased intestinal permeability and systemic inflammation, which in turn exacerbates neuroinflammation and neurodegeneration. Such insights into the interaction between gut microbiota and the brain-gut axis not only elucidate PD's underlying mechanisms but also pave the way for novel therapeutic interventions. We propose targeted treatment strategies, including dietary modifications and fecal microbiota transplantation, aimed at modulating the gut microbiota. These approaches hold promise for augmenting current PD treatment modalities by alleviating both motor and non-motor symptoms, thereby potentially improving patient quality of life. This research underscores the significance of the gut microbiota in the progression and treatment of PD, advocating for an integrated, multidisciplinary approach to develop personalized, efficacious management strategies for PD patients, combining insights from neurology, microbiology, and nutritional science.

Optimization of the Preparation Process of Glucuronomannan Oligosaccharides and Their Effects on the Gut Microbiota in MPTP-Induced PD Model Mice

Parkinson's disease (PD) is a prevalent neurodegenerative disorder, and accumulating evidence suggests a link between dysbiosis of the gut microbiota and the onset and progression of PD. In our previous investigations, we discovered that intraperitoneal administration of glucuronomannan oligosaccharides (GMn) derived from Saccharina japonica exhibited neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. However, the complicated preparation process, difficulties in isolation, and remarkably low yield have constrained further exploration of GMn. In this study, we optimized the degradation conditions in the preparation process of GMn through orthogonal experiments. Subsequently, an MPTP-induced PD model was established, followed by oral administration of GMn. Through a stepwise optimization, we successfully increased the yield of GMn, separated from crude fucoidan, from 1~2/10,000 to 4~8/1000 and indicated the effects on the amelioration of MPTP-induced motor deficits, preservation of dopamine neurons, and elevation in striatal neurotransmitter levels. Importantly, GMn mitigated gut microbiota dysbiosis induced by MPTP in mice. In particular, GM2 significantly reduced the levels of Akkermansia, Verrucomicrobiota, and Lactobacillus, while promoting the abundance of Roseburia and Prevotella compared to the model group. These findings suggest that GM2 can potentially suppress PD by modulating the gut microbiota, providing a foundation for the development of a novel and effective anti-PD marine drug.

Effects of dietary intervention on human diseases: molecular mechanisms and therapeutic potential

Diet, serving as a vital source of nutrients, exerts a profound influence on human health and disease progression. Recently, dietary interventions have emerged as promising adjunctive treatment strategies not only for cancer but also for neurodegenerative diseases, autoimmune diseases, cardiovascular diseases, and metabolic disorders. These interventions have demonstrated substantial potential in modulating metabolism, disease trajectory, and therapeutic responses. Metabolic reprogramming is a hallmark of malignant progression, and a deeper understanding of this phenomenon in tumors and its effects on immune regulation is a significant challenge that impedes cancer eradication. Dietary intake, as a key environmental factor, can influence tumor metabolism. Emerging evidence indicates that dietary interventions might affect the nutrient availability in tumors, thereby increasing the efficacy of cancer treatments. However, the intricate interplay between dietary interventions and the pathogenesis of cancer and other diseases is complex. Despite encouraging results, the mechanisms underlying diet-based therapeutic strategies remain largely unexplored, often resulting in underutilization in disease management. In this review, we aim to illuminate the potential effects of various dietary interventions, including calorie restriction, fasting-mimicking diet, ketogenic diet, protein restriction diet, high-salt diet, high-fat diet, and high-fiber diet, on cancer and the aforementioned diseases. We explore the multifaceted impacts of these dietary interventions, encompassing their immunomodulatory effects, other biological impacts, and underlying molecular mechanisms. This review offers valuable insights into the potential application of these dietary interventions as adjunctive therapies in disease management.

Dietary Restriction Improves Perioperative Neurocognitive Disorders by Inhibiting Neuroinflammation and Gut Microbial Dysbiosis

Anesthesia/surgery have been identified as potential factors contributing to perioperative neurocognitive disorders, with a notably heightened risk observed in aging populations. One of the primary drivers of this impairment is believed to be neuroinflammation, specifically inflammation of hippocampal microglia. Dietary restriction has demonstrated a favorable impact on cognitive impairment across various disorders, primarily by quelling neuroinflammation. However, the precise influence of dietary restriction on perioperative neurocognitive disorders remains to be definitively ascertained. This investigation aims to explore the effects of dietary restriction on perioperative neurocognitive disorders and propose innovative therapeutic strategies for their management. The model of perioperative neurocognitive disorder was induced through exploratory laparotomy under isoflurane anesthesia. Cognitive performance was evaluated using the open field test, Barnes maze test, and fear conditioning test. The enzyme-linked immunosorbent assay (ELISA) was employed to quantify concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in both serum and hippocampal samples. The Western blot technique was utilized to assess expression levels of hippocampal PSD 95, Synaptophysin, TLR4, MyD88, and NF-kB p65. Microglial polarization was gauged using a combination of reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence labeling techniques. We conducted 16S rRNA sequencing to investigate the impact of dietary restriction on the intestinal flora of aged mice following anesthesia/surgery. Our findings indicate that dietary restrictions have the potential to ameliorate anesthesia/surgery-induced cognitive dysfunction. This effect is achieved through the modulation of gut microbiota, suppression of inflammatory responses in hippocampal microglia, and facilitation of neuronal repair and regeneration.

Effects of the periodic fasting-mimicking diet on health, lifespan, and multiple diseases: a narrative review and clinical implications

Dietary restriction and fasting have been recognized for their beneficial effects on health and lifespan and their potential application in managing chronic metabolic diseases. However, long-term adherence to strict dietary restrictions and prolonged fasting poses challenges for most individuals and may lead to unhealthy rebound eating habits, negatively affecting overall health. As a result, a periodic fasting-mimicking diet (PFMD), involving cycles of fasting for 2 or more days while ensuring basic nutritional needs are met within a restricted caloric intake, has gained widespread acceptance. Current research indicates that a PFMD can promote stem cell regeneration, suppress inflammation, extend the health span of rodents, and improve metabolic health, among other effects. In various disease populations such as patients with diabetes, cancer, multiple sclerosis, and Alzheimer's disease, a PFMD has shown efficacy in alleviating disease symptoms and improving relevant markers. After conducting an extensive analysis of available research on the PFMD, it is evident that its advantages and potential applications are comparable to other fasting methods. Consequently, it is proposed in this review that a PFMD has the potential to fully replace water-only or very-low-energy fasting regimens and holds promise for application across multiple diseases.

A bibliometric analysis of the Fasting-Mimicking Diet

The Fasting-Mimicking Diet (FMD) is a nutritional strategy that involves significantly reducing calorie intake for a specific period to mimic the physiological effects of fasting while still providing the body with nutrition. Our study aimed to conduct a bibliometric study to explore the latest publishing trends and areas of intense activity within the sphere of FMD. We extracted data on FMD publications from the Web of Science Core Collection (WOSCC) database. The bibliometric analysis was conducted by WOSCC Online Analysis Platform and VOSviewer 1.6.16. In total, there were 169 publications by 945 authors from 342 organizations and 25 countries/regions, and published in 111 journals. The most productive country, organization, author, and journal were the United States, the University of Southern California, Valter D. Longo, and Nutrients, respectively. The first high-cited document was published in Ageing Research Reviews and authored by Mattson et al. In this study, they discuss the various health benefits of FMD including improved metabolic health, weight management, and even potential effects on delaying aging processes and reducing the risk of chronic diseases. In conclusion, our study is the first bibliometric analysis of the FMD. The main research hotspots and frontiers were FMD for cancer, FMD for metabolic-related diseases, and FMD for cognitive improvement. FMD may have some potential benefits for multiple diseases which should be further investigated.

Gut microbiota defined epigenomes of Alzheimer's and Parkinson's diseases reveal novel targets for therapy

The origins of Alzheimer's disease (AD) and Parkinson's disease (PD) involve genetic mutations, epigenetic changes, neurotoxin exposure and gut microbiota dysregulation. The gut microbiota's dynamic composition and its metabolites influence intestinal and blood-brain barrier integrity, contributing to AD and PD development. This review explores protein misfolding, aggregation and epigenetic links in AD and PD pathogenesis. It also highlights the role of a leaky gut and the microbiota-gut-brain axis in promoting these diseases through inflammation-induced epigenetic alterations. In addition, we investigate the potential of diet, probiotics and microbiota transplantation for preventing and treating AD and PD via epigenetic modifications, along with a discussion related to current challenges and future considerations. These approaches offer promise for translating research findings into practical clinical applications.

Fasting and Cognitive Impairment

Fasting is a nutritional practice involving complete food restriction for a varying length of time [...].

Compound Dihuang Granule Changes Gut Microbiota of MPTP-Induced Parkinson's Disease Mice via Inhibiting TLR4/NF-κB Signaling

Intestinal microbiota was connected to Parkinson's Disease (PD) pathology. The ancient Chinese medication for PD is Compound Dihuang Granule (CDG), and we found a neuroprotective function in treating the constipation of PD patients. Nevertheless, the mechanism of action still needs to be clarified. We predicted the probable targets of CDG against PD through Traditional Chinese medicine (TCM) network pharmacology and verified the analysis through animal experiments in vivo. The protein-protein interaction (PPI) network analysis screened PD-related genes, including Toll-like receptor 4(TLR4), TANK-binding kinase 1(TBK1), Nuclear Factor- Kappa B (NF-κB), and Tumor necrosis factor (TNF). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses proved that the NF-κB and toll-like receptor signaling pathways serve a key function in CDG therapy of PD. Molecular docking analysis demonstrated that CDG strongly connected to TLR4/NF-κB. Experiments findings indicated that CDG improved the damage of dopaminergic neurons and gut microbial dysbiosis, ameliorated motor impairments, and suppressed the PD-associated inflammation and oxidative stress in mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahy dropyridine (MPTP). CDG suppressed the inflammatory proteins in the colon and protected the intestinal barrier. Overall, CDG improved gut microbial in PD by blocking the pathway of TLR4/NF-κB.

5-HT4 Receptor is Protective for MPTP-induced Parkinson's Disease Mice Via Altering Gastrointestinal Motility or Gut Microbiota

Serotonergic dysfunction is related to both motor and nonmotor symptoms in Parkinson's disease (PD). As a 5-HT receptor, 5-HT4 receptor (5-HT4R) is well-studied and already-used in clinical therapy of constipation, which is a typical non-motor symptom in PD. In this study, we investigated the role of 5-HT4R as a regulator of gut function in MPTP-induced acute PD mice model. Daily intraperitoneal injection of GR 125487 (5-HT4R antagonist) was administered 3 days before MPTP treatment until sacrifice. Seven days post-MPTP treatment, feces were collected and gastrointestinal transit time (GITT) was measured, 8 days post-MPTP treatment, behavioral tests were performed, and then animals were sacrificed for the further analysis. We found GR 125487 pretreatment not only increased GITT, but also aggravated MPTP-induced motor bradykinesia. In addition, GR 125487 pretreatment exacerbated the loss of dopaminergic neurons probably by suppressing JAK2/PKA/CREB signaling pathway and increased reactive glia and neuroinflammation in the striatum. 16 S rRNA sequencing of fecal microbiota showed that GR 125487 pretreatment altered the composition of gut microbiota, in which the abundance of Akkermansia muciniphila and Clostridium clostridioforme was increased, whereas that of Parabacteroides distasonis and Bacteroides fragilis was decreased, which are closely associated with inflammation condition. Taken together, we demonstrated that GR 125487 pretreatment exacerbates MPTP-induced striatal neurodegenerative processes possibly via the JAK2/PKA/CREB pathway and neuroinflammation by altering gut microbiota composition. In the microbiota-gut-brain axis of PD, 5-HT4R should be further explored and might serve as a target for PD diagnosis and treatment.

Oral Administration of Silybin Protects Against MPTP-Induced Neurotoxicity by Reducing Pro-inflammatory Cytokines and Preserving BDNF Levels in Mice

Parkinson's disease (PD) is the second most frequent neurodegenerative disease associated with motor dysfunction secondary to the loss of dopaminergic neurons in the nigrostriatal axis. Actual therapy consists mainly of levodopa; however, its long-term use promotes secondary effects. Consequently, finding new therapeutic alternatives, such as neuroprotective molecules, is necessary. Among these alternatives is silybin (Sb), the major bioactive flavonolignan in silymarin. Both exert neuroprotective effects, preserving dopamine levels and dopaminergic neurons when administered in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse PD model, being probably Sb the potential therapeutic molecule behind this effect. To elucidate the role of Sb in the PD model, we determined the dose-dependent conservation of striatal dopamine content following Sb oral administration. Then, we evaluated motor deficit tests using the best dopamine conservative dose of Sb and determined a cytokine-dependent inflammatory profile status, malondialdehyde as an oxidative stress product, and neurotrophic factors content in the MPTP-induced mouse PD model. Our results show that oral Sb at 100 mg/kg dose conserved about 60% dopamine levels. Also, Sb improved motor deficits, preserved neurotrophic factors content and mitochondrial function, reduced lipid peroxidation, diminished proinflammatory cytokines to basal levels, enhanced fractalkine production in the striatum and substantia nigra, and increased IL-10 and IL-4 levels in the substantia nigra in the MPTP mice. Thus, oral Sb may be a potential pharmacological PD treatment alternative.

Healthy Human Fecal Microbiota Transplantation into Mice Attenuates MPTP-Induced Neurotoxicity via AMPK/SOD2 Pathway

Increasing evidence has shown that gut dysbacteriosis may play a crucial role in neuroinflammation in Parkinson's disease (PD). However, the specific mechanisms that link gut microbiota to PD remain unexplored. Given the critical roles of blood-brain barrier (BBB) dysfunction and mitochondrial dysfunction in the development of PD, we aimed to evaluate the interactions among the gut microbiota, BBB, and mitochondrial resistance to oxidation and inflammation in PD. We investigated the effects of fecal microbiota transplantation (FMT) on the physiopathology of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. The aim was to explore the role of fecal microbiota from PD patients and healthy human controls in neuroinflammation, BBB components, and mitochondrial antioxidative capacity via the AMPK/SOD2 pathway. Compared to control mice, MPTP-treated mice exhibited elevated levels of Desulfovibrio, whereas mice given FMT from PD patients exhibited enriched levels of Akkermansia and mice given FMT from healthy humans showed no significant alterations in gut microbiota. Strikingly, FMT from PD patients to MPTP-treated mice significantly aggravated motor impairments, dopaminergic neurodegeneration, nigrostriatal glial activation and colonic inflammation, and inhibited the AMPK/SOD2 signaling pathway. However, FMT from healthy human controls greatly improved the aforementioned MPTP-caused effects. Surprisingly, the MPTP-treated mice displayed a significant loss in nigrostriatal pericytes, which was restored by FMT from healthy human controls. Our findings demonstrate that FMT from healthy human controls can correct gut dysbacteriosis and ameliorate neurodegeneration in the MPTP-induced PD mouse model by suppressing microgliosis and astrogliosis, ameliorating mitochondrial impairments via the AMPK/SOD2 pathway, and restoring the loss of nigrostriatal pericytes and BBB integrity. These findings raise the possibility that the alteration in the human gut microbiota may be a risk factor for PD and provide evidence for potential application of FMT in PD preclinical treatment.

Oral pathogens exacerbate Parkinson's disease by promoting Th1 cell infiltration in mice

BACKGROUND

Parkinson's disease (PD) is a common chronic neurological disorder with a high risk of disability and no cure. Periodontitis is an infectious bacterial disease occurring in periodontal supporting tissues. Studies have shown that periodontitis is closely related to PD. However, direct evidence of the effect of periodontitis on PD is lacking. Here, we demonstrated that ligature-induced periodontitis with application of subgingival plaque (LIP-SP) exacerbated motor dysfunction, microglial activation, and dopaminergic neuron loss in 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice.

RESULTS

The 16S rRNA gene sequencing revealed that LIP-SP induced oral and gut dysbiosis. Particularly, Veillonella parvula (V. parvula) and Streptococcus mutans (S. mutans) from oral ligatures were increased in the fecal samples of MPTP + LIP-SP treated mice. We further demonstrated that V. parvula and S. mutans played crucial roles in LIP-SP mediated exacerbation of motor dysfunction and neurodegeneration in PD mice. V. parvula and S. mutans caused microglial activation in the brain, as well as T helper 1 (Th1) cells infiltration in the brain, cervical lymph nodes, ileum and colon in PD mice. Moreover, we observed a protective effect of IFNγ neutralization on dopaminergic neurons in V. parvula- and S. mutans-treated PD mice.

CONCLUSIONS

Our study demonstrates that oral pathogens V. parvula and S. mutans necessitate the existence of periodontitis to exacerbate motor dysfunction and neurodegeneration in MPTP-induced PD mice. The underlying mechanisms include alterations of oral and gut microbiota, along with immune activation in both brain and peripheral regions. Video Abstract.

SIRT1-dependent mitochondrial biogenesis supports therapeutic effects of vidarabine against rotenone-induced neural cell injury

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, which is distinguished by the loss of dopaminergic (DA) neurons in the substantia nigra and the formation of intraneuronal. Numerous studies showed that the damage and dysfunction of mitochondria may play key roles in DA neuronal loss. Thus, it is necessary to seek therapeutic measures for PD targeting mitochondrial function and biogenesis. In this study, through screening the purchased compound library, we found that marine derived vidarabine had significant neuroprotective effects against rotenone (ROT) induced SH-SY5Y cell injury. Further studies indicated that vidarabine pretreatment significantly protected ROT-treated SH-SY5Y cells from toxicity by preserving mitochondrial morphology, improving mitochondrial function, and reducing cell apoptosis. Vidarabine also reduced the oxidative stress and increased the expression levels of PGC-1α, NRF1, and TFAM proteins, which was accompanied by the increased mitochondrial biogenesis. However, the neuroprotective effects of vidarabine were counteracted in the presence of SIRT1-specific inhibitor Ex-527. Besides, vidarabine treatment attenuated the weight loss, alleviated the motor deficits and inhibited the neuronal injury in the MPTP induced mouse model. Thus, vidarabine may exert neuroprotective effects via a mechanism involving specific connections between the SIRT1-dependent mitochondrial biogenesis and its antioxidant capacity, suggesting that vidarabine has potential to be developed into a novel therapeutic agent for PD.

Intermittent fasting in health and disease

CONTEXT

Intermittent fasting, a new-age dietary concept derived from an age-old tradition, involves repetitive cycles of fasting/calorie restriction and eating.

OBJECTIVE

We aim to take a deep dive into the biological responses to intermittent fasting, delineate the disease-modifying and cognitive effects of intermittent fasting, and also shed light on the possible side effects.

METHODS

Numerous in vitro and in vivo studies were reviewed, followed by an in-depth analysis, and compilation of their implications in health and disease.

RESULTS

Intermittent fasting improves the body's stress tolerance, which is further amplified with exercise. It impacts various pathological conditions like cancer, obesity, diabetes, cardiovascular disease, and neurodegenerative diseases.

CONCLUSION

During dietary restriction, the human body experiences a metabolic switch due to the depletion of liver glycogen, which promotes a shift towards utilising fatty acids and ketones in the system, thereby significantly impacting adiposity, ageing and the immune response to various diseases.

Safety and feasibility of faecal microbiota transplantation for patients with Parkinson's disease: a protocol for a self-controlled interventional donor-FMT pilot study

INTRODUCTION

Experimental studies suggest a role of gut microbiota in the pathophysiology of Parkinson's disease (PD) via the gut-brain axis. The gut microbiota can also influence the metabolism of levodopa, which is the mainstay of treatment of PD. Therefore, modifying the gut microbiota by faecal microbiota transplantation (FMT) could be a supportive treatment strategy.

METHODS AND ANALYSIS

We have developed a study protocol for a single-centre, prospective, self-controlled, interventional, safety and feasibility donor-FMT pilot study with randomisation and double-blinded allocation of donor faeces. The primary objectives are feasibility and safety of FMT in patients with PD. Secondary objectives include exploring whether FMT leads to alterations in motor complications (fluctuations and dyskinesias) and PD motor and non-motor symptoms (including constipation), determining alterations in gut microbiota composition, assessing donor-recipient microbiota similarities and their association with PD symptoms and motor complications, evaluating the ease of the study protocol and examining FMT-related adverse events in patients with PD. The study population will consist of 16 patients with idiopathic PD that use levodopa and experience motor complications. They will receive FMT with faeces from one of two selected healthy human donors. FMT will be administered via a gastroscope into the duodenum, after treatment with oral vancomycin, bowel lavage and domperidone. There will be seven follow-up moments during 12 months.

ETHICS AND DISSEMINATION

This study was approved by the Medical Ethical Committee Leiden Den Haag Delft (ref. P20.087). Study results will be disseminated through publication in peer-reviewed journals and international conferences.

TRIAL REGISTRATION NUMBER

International Clinical Trial Registry Platform: NL9438.

Protective effects of dioscin against Parkinson's disease via regulating bile acid metabolism through remodeling gut microbiome/GLP-1 signaling

It is necessary to explore potent therapeutic agents via regulating gut microbiota and metabolism to combat Parkinson's disease (PD). Dioscin, a bioactive steroidal saponin, shows various activities. However, its effects and mechanisms against PD are limited. In this study, dioscin dramatically alleviated neuroinflammation and oxidative stress, and restored the disorders of mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). 16 S rDNA sequencing assay demonstrated that dioscin reversed MPTP-induced gut dysbiosis to decrease Firmicutes-to-Bacteroidetes ratio and the abundances of Enterococcus, Streptococcus, Bacteroides and Lactobacillus genera, which further inhibited bile salt hydrolase (BSH) activity and blocked bile acid (BA) deconjugation. Fecal microbiome transplantation test showed that the anti-PD effect of dioscin was gut microbiota-dependent. In addition, non-targeted fecal metabolomics assays revealed many differential metabolites in adjusting steroid biosynthesis and primary bile acid biosynthesis. Moreover, targeted bile acid metabolomics assay indicated that dioscin increased the levels of ursodeoxycholic acid, tauroursodeoxycholic acid, taurodeoxycholic acid and β-muricholic acid in feces and serum. In addition, ursodeoxycholic acid administration markedly improved the protective effects of dioscin against PD in mice. Mechanistic test indicated that dioscin significantly up-regulated the levels of takeda G protein-coupled receptor 5 (TGR5), glucagon-like peptide-1 receptor (GLP-1R), GLP-1, superoxide dismutase (SOD), and down-regulated NADPH oxidases 2 (NOX2) and nuclear factor-kappaB (NF-κB) levels. Our data indicated that dioscin ameliorated PD phenotype by restoring gut dysbiosis and regulating bile acid-mediated oxidative stress and neuroinflammation via targeting GLP-1 signal in MPTP-induced PD mice, suggesting that the compound should be considered as a prebiotic agent to treat PD in the future.

Orally Induced High Serum Level of Trimethylamine N-oxide Worsened Glial Reaction and Neuroinflammation on MPTP-Induced Acute Parkinson's Disease Model Mice

Neuroinflammation mediated by brain glial cells is one of the pathological drivers of Parkinson's disease (PD). Recent studies have shown that higher circulating trimethylamine N-oxide (TMAO, a gut microbiota-derived metabolite) can induce neuroinflammation and are strongly related to a variety of central nervous system diseases and adverse brain events. Herein, we explored the effect of pre-existing higher circulating TMAO on dopamine system and neuroinflammation in acute PD model mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydroxypyridine (MPTP). TMAO pretreatment was given by adding 3% (w/v) TMAO to drinking water of mice for 21 days to induce higher circulating TMAO status, then mice were administered with MPTP (20 mg/kg, i.p) for four times in one day to construct an acute PD model mice and treated with TMAO continuously until the end of the experiment. Results demonstrated that TMAO treatment significantly increased serum TMAO levels. Moreover, high serum TMAO significantly increased activation of microglia and astrocytes both in striatum and in substantia nigra. And strikingly, high serum TMAO significantly promoted the metabolism of striatal dopamine (DA) of PD model mice, although it had no significant effect on the number of dopaminergic neurons or the content of DA. Furthermore, immunofluorescence, ELISA, and RT-qPCR results of the hippocampus also showed that high serum TMAO significantly promoted the activation of microglia and astrocytes in the dentate gyrus, increased the levels of TNF-α and IL-1β, and upregulated gene expression of M1 microglia-related markers (including CD16, CD32, and iNOS) and A2 astrocyte-related markers (including S100a10, Ptx3, and Emp1) in mRNA levels. In summary, we found that pre-existing high serum levels of TMAO worsened the PD-related brain pathology by promoting DA metabolism, aggravating neuroinflammation and regulating glial cell polarization.

Fecal Microbiota Transplantation from Aged Mice Render Recipient Mice Resistant to MPTP-Induced Nigrostriatal Degeneration Via a Neurogenesis-Dependent but Inflammation-Independent Manner

Accumulating data support a crucial role of gut microbiota in Parkinson's disease (PD). However, gut microbiota vary with age and, thus, will affect PD in an age-dependent, but unknown manner. We examined the effects of fecal microbiota transplantation (FMT) pretreatment, using fecal microbiota from young (7 weeks) or aged mice (23 months), on MPTP-induced PD model. Motor function, pathological changes, striatal neurotransmitters, neuroinflammation, gut inflammation and gut permeability were examined. Gut microbiota composition and metabolites, namely short-chain fatty acids (SCFAs), were analyzed. Neurogenesis was also evaluated by measuring the number of doublecortin-positive (DCX+) neurons and Ki67-positive (Ki67+) cells in the hippocampus. Expression of Cd133 mRNA, a cellular stemness marker, in the hippocampus was also examined. Mice who received FMT from young mice showed MPTP-induced motor dysfunction, and reduction of striatal dopamine (DA), dopaminergic neurons and striatal tyrosine hydroxylase (TH) levels. Interestingly and unexpectedly, mice that received FMT from aged mice showed recovery of motor function and rescue of dopaminergic neurons and striatal 5-hydroxytryptamine (5-HT), as well as decreased DA metabolism after MPTP challenge. Further, they showed improved metabolic profiling and a decreased amount of fecal SCFAs. High-throughput sequencing revealed that FMT remarkably reshaped the gut microbiota of recipient mice. For instance, levels of genus Akkermansia and Candidatus Saccharimonas were elevated in fecal samples of recipient mice receiving aged microbiota (AM + MPTP mice) than YM + MPTP mice. Intriguingly, both young microbiota and aged microbiota had no effect on neuroinflammation, gut inflammation or gut permeability. Notably, AM + MPTP mice showed a marked increase in DCX+ neurons, as well as Ki67+ cells and Cd133 expression in the hippocampal dentate gyrus (DG) compared to YM + MPTP mice. These results suggest that FMT from aged mice augments neurogenesis, improves motor function and restores dopaminergic neurons and neurotransmitters in PD model mice, possibly through increasing neurogenesis.

Gut Microbial Metabolome and Dysbiosis in Neurodegenerative Diseases: Psychobiotics and Fecal Microbiota Transplantation as a Therapeutic Approach-A Comprehensive Narrative Review

The comprehensive narrative review conducted in this study delves into the mechanisms of communication and action at the molecular level in the human organism. The review addresses the complex mechanism involved in the microbiota-gut-brain axis as well as the implications of alterations in the microbial composition of patients with neurodegenerative diseases. The pathophysiology of neurodegenerative diseases with neuronal loss or death is analyzed, as well as the mechanisms of action of the main metabolites involved in the bidirectional communication through the microbiota-gut-brain axis. In addition, interventions targeting gut microbiota restructuring through fecal microbiota transplantation and the use of psychobiotics-pre- and pro-biotics-are evaluated as an opportunity to reduce the symptomatology associated with neurodegeneration in these pathologies. This review provides valuable information and facilitates a better understanding of the neurobiological mechanisms to be addressed in the treatment of neurodegenerative diseases.

Ketogenic diet protects MPTP-induced mouse model of Parkinson's disease via altering gut microbiota and metabolites

The ketogenic diet (KD) is a low-carbohydrate, high-fat regime that is protective against neurodegenerative diseases. However, the impact of KD on Parkinson's disease (PD) and its mechanisms remains unclear. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD was fed with KD for 8 weeks. Motor function and dopaminergic neurons were evaluated. Inflammation in the brain, plasma, and colon tissue were also measured. Fecal samples were assessed by 16S rDNA gene sequencing and untargeted metabolomics. We found that KD protected motor dysfunction, dopaminergic neuron loss, and inflammation in an MPTP mouse model of PD. 16S rDNA sequencing revealed that MPTP administration significantly increased Citrobacter, Desulfovibrio, and Ruminococcus, and decreased Dubosiella, whereas KD treatment reversed the dysbiosis. Meanwhile, KD regulated the MPTP-induced histamine, N-acetylputrescine, d-aspartic acid, and other metabolites. Fecal microbiota transplantation using feces from the KD-treated mice attenuated the motor function impairment and dopaminergic neuron loss in antibiotic-pretreated PD mice. Our current study demonstrates that KD played a neuroprotective role in the MPTP mouse model of PD through the diet-gut microbiota-brain axis, which may involve inflammation in the brain and colon. However, future research is warranted to explore the explicit anti-inflammatory mechanisms of the gut-brain axis in PD models fed with KD.

Vancomycin Pretreatment on MPTP-Induced Parkinson's Disease Mice Exerts Neuroprotection by Suppressing Inflammation Both in Brain and Gut

A growing body of evidence implies that gut microbiota was involved in pathogenesis of Parkinson's disease (PD), but the mechanism is still unclear. The aim of this study is to investigate the effects of antibiotics pretreatment on the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD mice. In this study, vancomycin pretreatment was given by gavage once daily with either vancomycin or distilled water for 14 days to mice, then mice were administered with MPTP (20 mg/kg, i.p) for four times in one day to establish an acute PD model. Results show that vancomycin pretreatment significantly improved motor dysfunction of mice in pole and traction tests. Although vancomycin pretreatment had no effect on dopamine (DA) or the process of DA synthesis, it inhibited the metabolism of DA by suppressing the expression of striatal monoamine oxidase B (MAO-B). Furthermore, vancomycin pretreatment reduced the number of astrocytes and microglial cells in the substantia nigra pars compacta (SNpc) to alleviate neuroinflammation, decreased the expression of TLR4/MyD88/NF-κB/TNF-α signaling pathway in both brain and gut. Meanwhile, vancomycin pretreatment changed gut microbiome composition and the levels of fecal short chain fatty acids (SCFAs). The abundance of Akkermansia and Blautia increased significantly after vancomycin pretreatment, which might be related to inflammation and inhibition of TLR4 signaling pathway. In summary, these results demonstrate that the variation of gut microbiota and its metabolites induced by vancomycin pretreatment might decrease dopamine metabolic rate and relieve inflammation in both gut and brain via the microbiota-gut-brain axis in MPTP-induced PD mice. The neuroprotection of vancomycin pretreatment on MPTP-induced Parkinson's disease mice The alterations of gut microbiota and SCFAs induced by vancomycin pretreatment might not only improve motor dysfunction, but also decrease dopamine metabolism and relieve inflammation in both brain and gut via TLR4/MyD88/NF-κB/TNF-α pathway in MPTP-induced PD mice.

The role of the microbiota-gut-brain axis and intestinal microbiome dysregulation in Parkinson's disease

Parkinson's disease (PD) is a complex progressive neurodegenerative disease associated with aging. Its main pathological feature is the degeneration and loss of dopaminergic neurons related to the misfolding and aggregation of α-synuclein. The pathogenesis of PD has not yet been fully elucidated, and its occurrence and development process are closely related to the microbiota-gut-brain axis. Dysregulation of intestinal microbiota may promote the damage of the intestinal epithelial barrier, intestinal inflammation, and the upward diffusion of phosphorylated α-synuclein from the enteric nervous system (ENS) to the brain in susceptible individuals and further lead to gastrointestinal dysfunction, neuroinflammation, and neurodegeneration of the central nervous system (CNS) through the disordered microbiota-gut-brain axis. The present review aimed to summarize recent advancements in studies focusing on the role of the microbiota-gut-brain axis in the pathogenesis of PD, especially the mechanism of intestinal microbiome dysregulation, intestinal inflammation, and gastrointestinal dysfunction in PD. Maintaining or restoring homeostasis in the gut microenvironment by targeting the gut microbiome may provide future direction for the development of new biomarkers for early diagnosis of PD and therapeutic strategies to slow disease progression.

Trimethylamine N-Oxide Exacerbates Neuroinflammation and Motor Dysfunction in an Acute MPTP Mice Model of Parkinson's Disease

Observational studies have shown abnormal changes in trimethylamine N-oxide (TMAO) levels in the peripheral circulatory system of Parkinson's disease (PD) patients. TMAO is a gut microbiota metabolite that can cross the blood-brain barrier and is strongly related to neuroinflammation. Neuroinflammation is one of the pathological drivers of PD. Herein, we investigated the effect of TMAO on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. TMAO pretreatment was given by adding 1.5% (w/v) TMAO to the drinking water of the mice for 21 days; then, the mice were administered MPTP (20 mg/kg, i.p.) four times a day to construct an acute PD model. Their serum TMAO concentrations, motor function, dopaminergic network integrity, and neuroinflammation were then assayed. The results showed that TMAO partly aggravated the motor dysfunction of the PD mice. Although TMAO had no effect on the dopaminergic neurons, TH protein content, and striatal DA level in the PD mice, it significantly reduced the striatal 5-HT levels and aggravated the metabolism of DA and 5-HT. Meanwhile, TMAO significantly activated glial cells in the striatum and the hippocampi of the PD mice and promoted the release of inflammatory cytokines in the hippocampus. In summary, higher-circulating TMAO had adverse effects on the motor capacity, striatum neurotransmitters, and striatal and hippocampal neuroinflammation in PD mice.

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.

ZINC (Zn) AND ADIPOSE-DERIVED MESENCHYMAL STEM CELLS (AD-MSCs) ON MPTP-INDUCED PARKINSON'S DISEASE MODEL: A COMPARATIVE EVALUATION OF BEHAVIORAL AND IMMUNOHISTOCHEMICAL RESULTS

Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons and sustained neuroinflammation due to microglial activation. Adipose tissue-derived mesenchymal stem cells (AD-MSCs) secrete neuroprotective factors to prevent neuronal damage. Furthermore, Zn regulates stem cell proliferation and differentiation and has immunomodulatory functions. Our in vivo study aimed to investigate whether Zn affects the activities of AD-MSCs in the MPTP-induced mouse model. Male C57BL/6 mice were randomly divided into six groups (n=6): Control, Zn, PD, PD+Zn, PD+(AD-MSC), PD+(AD-MSC)+Zn. MPTP toxin (20mg/kg) was dissolved in saline and intraperitoneally injected into experimental groups for two days with 12h intervals. On the 3rd day, AD-MSCs were given to the right lateral ventricle of the PD+(AD-MSC) and PD+(AD-MSC)+Zn groups by stereotaxic surgery. Then, ZnSO₄H₂O was administered intraperitoneally for 4 days at 2mg/kg. Seven days post MPTP injection, the motor activities of the mouse were evaluated. Then immunohistochemical analyzes were performed in SNpc. Our results showed that motor activity was lower in Group PD. AD-MSC and Zn administration have improved this impairment. MPTP caused a decrease in TH and BDNF expressions in dopaminergic neurons in Group PD. However, TH and BDNF expressions were more intense in the other groups. MCP-1, TGF-β, and IL-10 expressions increased in administered groups compared to the Group PD. The present study indicates that Zn's individual and combined administration with AD-MSCs reduces neuronal damage in the MPTP-induced mouse model. In addition, anti-inflammatory responses that emerge with Zn and AD-MSCs may have a neuroprotective effect.

RIPK1-Induced A1 Reactive Astrocytes in Brain in MPTP-Treated Murine Model of Parkinson's Disease

Neuroinflammation is one of the hallmarks of Parkinson's disease, including the massive activation of microglia and astrocytes and the release of inflammatory factors. Receptor-interacting protein kinase 1 (RIPK1) is reported to mediate cell death and inflammatory signaling, and is markedly elevated in the brain in PD mouse models. Here, we aim to explore the role of RIPK1 in regulating the neuroinflammation of PD. C57BL/6J mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 20 mg/kg four times/day), followed by necrostatin-1 treatment (Nec-1, RIPK1 inhibitor; 1.65 mg/kg once daily for seven days. Notably, the first Nec-1 was given 12 h before MPTP modeling). Behavioral tests indicated that inhibition of RIPK1 greatly relieved motor dysfunction and anxiety-like behaviors of PD mice. It also increased striatal TH expression, rescue the loss of dopaminergic neurons, and reduce activation of astrocytes in the striatum of PD mice. Furthermore, inhibition of RIPK1 expression reduced A1 astrocytes' relative gene expression (CFB, H2-T23) and inflammatory cytokine or chemokine production (CCL2, TNF-α, IL-1β) in the striatum of PD mice. Collectively, inhibition of RIPK1 expression can provide neuroprotection to PD mice, probably through inhibition of the astrocyte A1 phenotype, and thus RIPK1 might be an important target in PD treatment.

Lactobacillus plantarum CCFM405 against Rotenone-Induced Parkinson’s Disease Mice via Regulating Gut Microbiota and Branched-Chain Amino Acids Biosynthesis

Recent studies have demonstrated that disturbances in the gut microbiota and microbiota -derived metabolites contribute to the pathogenesis of Parkinson’s disease (PD), suggesting that probiotic treatments that restore them may delay disease progression. This study aimed to examine the attenuating efficacy of L. plantarum CCFM405 and the potential mechanisms in mice with rotenone-induced PD. Our results indicate that L. plantarum CCFM405 ameliorated rotenone-induced motor deficits and constipation, decreased dopaminergic neuronal death, reduced intestinal inflammation and neuroinflammation, and raised dopamine levels, 5-HT, and associated metabolites in the striatal region of the brain in mice with PD. Sequencing of 16S rRNA from fecal microbiota revealed that L. plantarum CCFM405 normalized the gut bacterial composition in mice with PD, as evidenced by the increased relative abundance of the following genus, Bifidobacterium, Turicibacter, and Faecalibaculum, and decreased relative abundance of Alistipes, Bilophila, Akkermansia, and Escherichia-Shigella. The PICRUSt-predicted gut microbiota function revealed that L. plantarum CCFM405 enhanced the biosynthesis of amino acid pathways, particularly valine, leucine, and isoleucine (branched-chain amino acids, BCAAs). A non-metabolomic analysis of the serum and feces showed that L. plantarum CCFM405 markedly increased the levels of BCAAs. Pathway enrichment analysis based on the KEGG database further suggested that L. plantarum CCFM405 supplementation can promote BCAAs biosynthesis. Collectively, L. plantarum CCFM405 can help to prevent rotenone-induced PD by modulating the gut microbiota–metabolite axis. BCAAs may play a dominant role in L. plantarum CCFM405-associated neuroprotection in PD mice. This probiotic could be utilized as a potential food supplement in the management of PD.

Fasting: From Physiology to Pathology

Overnutrition is a risk factor for various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. Therefore, targeting overnutrition represents a simple but attractive strategy for the treatment of these increasing public health threats. Fasting as a dietary intervention for combating overnutrition has been extensively studied. Fasting has been practiced for millennia, but only recently have its roles in the molecular clock, gut microbiome, and tissue homeostasis and function emerged. Fasting can slow aging in most species and protect against various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. These centuried and unfading adventures and explorations suggest that fasting has the potential to delay aging and help prevent and treat diseases while minimizing side effects caused by chronic dietary interventions. In this review, recent animal and human studies concerning the role and underlying mechanism of fasting in physiology and pathology are summarized, the therapeutic potential of fasting is highlighted, and the combination of pharmacological intervention and fasting is discussed as a new treatment regimen for human diseases.

Disease mechanisms as subtypes: Microbiome

Abnormalities in gut microbiota have been suggested to be involved in the pathophysiology and progression of Parkinson's disease (PD). Gastrointestinal nonmotor symptoms often precede the onset of motor features in PD, suggesting a role for gut dysbiosis in neuroinflammation and α-synuclein (α-syn) aggregation. In the first part of this chapter, we analyze critical features of healthy gut microbiota and factors (environmental and genetic) that modify its composition. In the second part, we focus on the mechanisms underlying the gut dysbiosis and how it alters anatomically and functionally the mucosal barrier, triggering neuroinflammation and subsequently α-syn aggregation. In the third part, we describe the most common alterations in the gut microbiota of PD patients, dividing the gastrointestinal system in higher and lower tract to examine the association between microbiota abnormalities and clinical features. In the final section, we report on current and future therapeutic approaches to gut dysbiosis aiming to either reduce the risk for PD, modify the disease course, or improve the pharmacokinetic profile of dopaminergic therapies. We also suggest that further studies will be needed to clarify the role of the microbiome in PD subtyping and of pharmacological and nonpharmacological interventions in modifying specific microbiota profiles in individualizing disease-modifying treatments in PD.

Neuroprotective Effects of Sodium Butyrate by Restoring Gut Microbiota and Inhibiting TLR4 Signaling in Mice with MPTP-Induced Parkinson's Disease

Parkinson's disease (PD) is a prevalent type of neurodegenerative disease. There is mounting evidence that the gut microbiota is involved in the pathogenesis of PD. Sodium butyrate (NaB) can regulate gut microbiota and improve brain functioning in neurological disorders. Hence, we examined whether the neuroprotective function of NaB on PD was mediated by the modulation of gut microbial dysbiosis and revealed its possible mechanisms. Mice were administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 7 consecutive days to construct the PD model. NaB gavage was given 2 h after the daily MPTP injections for 21 days. NaB improved the motor functioning of PD mice, increased striatal neurotransmitter levels, and reduced the death of dopaminergic neurons. The 16S rRNA sequencing analysis revealed that NaB restored the gut microbial dysbiosis. NaB also attenuated the intestinal barrier's disruption and reduced serum, colon, and striatal pro-inflammatory cytokines, along with inhibiting the overactivation of glial cells, suggesting an inhibitory effect on inflammation from NaB throughout the gut-brain axis of the PD mice. Mechanistic studies revealed that NaB treatment suppressed the TLR4/MyD88/NF-kB pathway in the colon and striatum. In summary, NaB had a neuroprotective impact on the PD mice, likely linked to its regulation of gut microbiota to inhibit gut-brain axis inflammation.

Intermittent fasting protects the nigral dopaminergic neurons from MPTP-mediated dopaminergic neuronal injury in mice

Dietary restriction through low-calorie intake or intermittent fasting benefits many organs, including the brain. This study investigated the neuroprotective effects of fasting in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. We found that fasting every other day rather than weekly increased the levels of brain-derived neurotrophic factor and glial-derived neurotrophic factor in the nigrostriatal pathway. Therefore, we maintained the animals on alternate-day fasting for 2 weeks and injected MPTP (30 mg/kg/day, intraperitoneally [i.p.]) for five days. We observed that alternate-day fasting attenuated MPTP-induced dopaminergic neuronal loss and astroglial activation in the substantia nigra and the striatum. Moreover, neurochemical analysis using high-performance liquid chromatography showed that alternate-day fasting reduced MPTP-induced depletion of striatal dopamine. Consistent with these results, behavioral tests showed that fasting suppressed the motor impairment caused by MPTP. Furthermore, fasting increased the phosphorylation of phosphatidylinositol-3-kinase and protein kinase B, which are downstream signaling molecules of neurotrophic factors. Fasting also increased the phosphorylation of extracellular signal-regulated protein kinase and cAMP response element-binding protein, further supporting the involvement of neurotrophic factors in the observed neuroprotective effects. Hence, our results demonstrated the dopaminergic neuroprotection of intermittent fasting in an MPTP mouse model of Parkinson's disease, supporting the idea that fasting could be an instrumental tool for preventing neurodegeneration in the brain.

Parkinson's Disease, It Takes Guts: The Correlation between Intestinal Microbiome and Cytokine Network with Neurodegeneration

Parkinson's disease is a progressive neurodegenerative disorder with motor, physical and behavioral symptoms that can have a profound impact on the patient's quality of life. Most cases are idiopathic, and the exact mechanism of the disease's cause is unknown. The current hypothesis focuses on the gut-brain axis and states that gut microbiota dysbiosis can trigger inflammation and advances the development of Parkinson's disease. This systematic review presents the current knowledge of gut microbiota analysis and inflammation based on selected studies on Parkinson's patients and experimental animal models. Changes in gut microbiota correlate with Parkinson's disease, but only a few studies have considered inflammatory modulators as important triggers of the disease. Nevertheless, it is evident that proinflammatory cytokines and chemokines are induced in the gut, the circulation, and the brain before the development of the disease's neurological symptoms and exacerbate the disease. Increased levels of tumor necrosis factor, interleukin-1β, interleukin-6, interleukin-17A and interferon-γ can correlate with altered gut microbiota. Instead, treatment of gut dysbiosis is accompanied by reduced levels of inflammatory mediators in specific tissues, such as the colon, brain and serum and/or cerebrospinal fluid. Deciphering the role of the immune responses and the mechanisms of the PD-associated gut microbiota will assist the interpretation of the pathogenesis of Parkinson's and will elucidate appropriate therapeutic strategies.

Neurochemical, histological, and behavioral profiling of the acute, sub-acute, and chronic MPTP mouse model of Parkinson's disease

Parkinson's disease (PD) is a heterogeneous multi-systemic disorder unique to humans characterized by motor and non-motor symptoms. Preclinical experimental models of PD present limitations and inconsistent neurochemical, histological, and behavioral readouts. The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD is the most common in vivo screening platform for novel drug therapies; nonetheless, behavioral endpoints yielded amongst laboratories are often discordant and inconclusive. In this study, we characterized neurochemically, histologically, and behaviorally three different MPTP mouse models of PD to identify translational traits reminiscent of PD symptomatology. MPTP was intraperitoneally (i.p.) administered in three different regimens: (i) acute-four injections of 20 mg/kg of MPTP every 2 h; (ii) sub-acute-one daily injection of 30 mg/kg of MPTP for 5 consecutive days; and (iii) chronic-one daily injection of 4 mg/kg of MPTP for 28 consecutive days. A series of behavioral tests were conducted to assess motor and non-motor behavioral changes including anxiety, endurance, gait, motor deficits, cognitive impairment, circadian rhythm and food consumption. Impairments in balance and gait were confirmed in the chronic and acute models, respectively, with the latter showing significant correlation with lesion size. The sub-acute model, by contrast, presented with generalized hyperactivity. Both, motor and non-motor changes were identified in the acute and sub-acute regime where habituation to a novel environment was significantly reduced. Moreover, we report increased water and food intake across all three models. Overall, the acute model displayed the most severe lesion size, while across the three models striatal dopamine content (DA) did not correlate with the behavioral performance. The present study demonstrates that detection of behavioral changes following MPTP exposure is challenging and does not correlate with the dopaminergic lesion extent.

Dietary regulation in health and disease

Nutriments have been deemed to impact all physiopathologic processes. Recent evidences in molecular medicine and clinical trials have demonstrated that adequate nutrition treatments are the golden criterion for extending healthspan and delaying ageing in various species such as yeast, drosophila, rodent, primate and human. It emerges to develop the precision-nutrition therapeutics to slow age-related biological processes and treat diverse diseases. However, the nutritive advantages frequently diversify among individuals as well as organs and tissues, which brings challenges in this field. In this review, we summarize the different forms of dietary interventions extensively prescribed for healthspan improvement and disease treatment in pre-clinical or clinical. We discuss the nutrient-mediated mechanisms including metabolic regulators, nutritive metabolism pathways, epigenetic mechanisms and circadian clocks. Comparably, we describe diet-responsive effectors by which dietary interventions influence the endocrinic, immunological, microbial and neural states responsible for improving health and preventing multiple diseases in humans. Furthermore, we expatiate diverse patterns of dietotheroapies, including different fasting, calorie-restricted diet, ketogenic diet, high-fibre diet, plants-based diet, protein restriction diet or diet with specific reduction in amino acids or microelements, potentially affecting the health and morbid states. Altogether, we emphasize the profound nutritional therapy, and highlight the crosstalk among explored mechanisms and critical factors to develop individualized therapeutic approaches and predictors.

The Effects of Dietary Interventions on Brain Aging and Neurological Diseases

Dietary interventions can ameliorate age-related neurological decline. Decades of research of in vitro studies, animal models, and clinical trials support their ability and efficacy to improve behavioral outcomes by inducing biochemical and physiological changes that lead to a more resilient brain. Dietary interventions including calorie restriction, alternate day fasting, time restricted feeding, and fasting mimicking diets not only improve normal brain aging but also slow down, or even reverse, the progression of neurological diseases. In this review, we focus on the effects of intermittent and periodic fasting on improving phenotypic outcomes, such as cognitive and motor-coordination decline, in the normal aging brain through an increase in neurogenesis and synaptic plasticity, and decrease in neuroinflammation, mitochondrial dysfunction, and oxidative stress. We summarize the results of various dietary interventions in animal models of age-related neurological diseases such as Alzheimer's disease, Parkinson's disease, epilepsy, and Multiple Sclerosis and discuss the results of clinical trials that explore the feasibility of dietary interventions in the prevention and treatment of these diseases.

Probiotic Pediococcus pentosaceus ameliorates MPTP-induced oxidative stress via regulating the gut microbiota–gut–brain axis

Recent evidence demonstrated that functional bacteria were involved in the regulation of Parkinson’s disease (PD). However, the mechanism of probiotics in improving PD was unclear. Here the antioxidant effect and the mechanism of probiotics Pediococcus pentosaceus (PP) on PD were studied by regulating the gut–brain axis. In this study, male C57BL/6J mice were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intraperitoneally to establish a PD model and were then treated with PP for 4 weeks. Subsequently, a series of neurobehavioral tests to evaluate the motor function of the mice was performed. Additionally, degeneration of dopaminergic neurons, accumulation of α-synuclein, the production of an oxidative stress response, and the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related proteins were evaluated. Moreover, the gut microbial composition and the level of metabolite γ-aminobutyric acid (GABA) were assessed. The results showed that PP treatment could improve MPTP-induced motor deficits, the degeneration of dopaminergic neurons, and the accumulation of α-synuclein. Moreover, PP treatment significantly increased the levels of SOD1, Gpx1, and Nrf2, while it decreased the levels of Keap1 in the brain of MPTP-induced mice. Notably, PP treatment improved the gut microbial dysbiosis and increased the level of GABA in MPTP-induced mice. These findings indicated that PP might represent a promising candidate, due to the metabolite of GABA, that could be used for the treatment of PD.

Intermittent fasting protects against Alzheimer's disease in mice by altering metabolism through remodeling of the gut microbiota

Alzheimer's disease (AD) is the most common form of dementia without effective clinical treatment. Here, we show that intermittent fasting (IF) improves cognitive functions and AD-like pathology in a transgenic AD mouse model (5XFAD). IF alters gut microbial composition with a significant enrichment in probiotics such as Lactobacillus. The changes in the composition of the gut microbiota affect metabolic activities and metabolite production. Metabolomic profiling analysis of cecal contents revealed IF leads to a decreased carbohydrate metabolism (for example, glucose) and an increased abundance in amino acids (for example, sarcosine and dimethylglycine). Interestingly, we found that the administration of IF-elevated sarcosine or dimethylglycine mimics the protective effects of IF in 5XFAD mice, including the amelioration of cognitive decline, amyloid-β (Aβ) burden and glial overactivation. Our findings thus demonstrate an IF regimen is a potential approach to prevent AD progression, at least through the gut-microbiota-metabolites-brain axis, and constitutes an innovative AD therapeutic avenue.

The Interplay between Gut Microbiota and Parkinson's Disease: Implications on Diagnosis and Treatment

The bidirectional interaction between the gut microbiota (GM) and the Central Nervous System, the so-called gut microbiota brain axis (GMBA), deeply affects brain function and has an important impact on the development of neurodegenerative diseases. In Parkinson’s disease (PD), gastrointestinal symptoms often precede the onset of motor and non-motor manifestations, and alterations in the GM composition accompany disease pathogenesis. Several studies have been conducted to unravel the role of dysbiosis and intestinal permeability in PD onset and progression, but the therapeutic and diagnostic applications of GM modifying approaches remain to be fully elucidated. After a brief introduction on the involvement of GMBA in the disease, we present evidence for GM alterations and leaky gut in PD patients. According to these data, we then review the potential of GM-based signatures to serve as disease biomarkers and we highlight the emerging role of probiotics, prebiotics, antibiotics, dietary interventions, and fecal microbiota transplantation as supportive therapeutic approaches in PD. Finally, we analyze the mutual influence between commonly prescribed PD medications and gut-microbiota, and we offer insights on the involvement also of nasal and oral microbiota in PD pathology, thus providing a comprehensive and up-to-date overview on the role of microbial features in disease diagnosis and treatment.

Neuroprotective Effects of Sodium Butyrate and Monomethyl Fumarate Treatment through GPR109A Modulation and Intestinal Barrier Restoration on PD Mice

Research has connected Parkinson's disease (PD) with impaired intestinal barrier. The activation of G-protein-coupled receptor 109A (GPR109A) protects the intestinal barrier by inhibiting the NF-κB signaling pathway. Sodium butyrate (NaB), which is a GPR109A ligand, may have anti-PD effects. The current study's objective is to demonstrate that NaB or monomethyl fumarate (MMF, an agonist of the GPR109A) can treat PD mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) via repairing the intestinal barrier. Male C57BL/6J mice were divided into four groups randomly: control, MPTP + vehicle, MPTP + NaB, and MPTP + MMF. Modeling mice received MPTP (20 mg/kg/day, i.p.) for a week, while control mice received sterile PBS. Then, four groups each received two weeks of sterile PBS (10 mL/kg/day, i.g.), sterile PBS (10 mL/kg/day, i.g.), NaB (600 mg/kg/day, i.g.), or MMF (100 mg/kg/day, i.g.). We assessed the expression of tight junction (TJ) proteins (occludin and claudin-1), GPR109A, and p65 in the colon, performed microscopic examination via HE staining, quantified markers of intestinal permeability and proinflammatory cytokines in serum, and evaluated motor symptoms and pathological changes in the substantia nigra (SN) or striatum. According to our results, MPTP-induced defected motor function, decreased dopamine and 5-hydroxytryptamine levels in the striatum, decreased tyrosine hydroxylase-positive neurons and increased activated microglia in the SN, and systemic inflammation were ameliorated by NaB or MMF treatment. Additionally, the ruined intestinal barrier was also rebuilt and NF-κB was suppressed after the treatment, with higher levels of TJ proteins, GPR109A, and decreased intestinal permeability. These results show that NaB or MMF can remedy motor symptoms and pathological alterations in PD mice by restoring the intestinal barrier with activated GPR109A. We demonstrate the potential for repairing the compromised intestinal barrier and activating GPR109A as promising treatments for PD.

Dietary Restriction against Parkinson's Disease: What We Know So Far

Dietary restriction (DR) is defined as a moderate reduction in food intake while avoiding malnutrition. The beneficial effects of DR are being increasingly acknowledged in aging and in a series of age-related neurodegenerative disorders, for example, Parkinson's disease (PD). To date, the pathogenesis of PD remains elusive and there is no cure for it in spite of intensive research over decades. In this review, we summarize the current knowledge on the efficacy of DR on PD, focusing on the underlying mechanisms involving general metabolism, neuroendocrinolgy, neuroinflammation, gut microbiome, and so on. We anticipate that this review will provide future perspectives for PD prevention and treatment.

Fasting and metabolic syndrome: A systematic review and Meta-analyses

Objective: Fasting is considered to be a food structure that can improve body health. Several randomized clinical trials (RCTs) have investigated the effects of fasting in patients with metabolic syndrome (MS). In this review, we performed a meta-analysis to assess the effects of fasting on patients with MS. Methods: Following PRISMA guidelines, a systematic literature search was conducted in PubMed, Embase, and Cochrane Central updated to September 2021. The quality evaluation and heterogeneity detection of the included research literature were carried out by Revman and Stata software through a random-effects model. Results: A total of 268 subjects were included. The pooled results revealed that fasting significantly reduced body weight (WMD: -2.48 kg, 95% CI: -3.22, -1.74), BMI (WMD = -2.72 cm; 95%CI: -4.04, -1.40 cm), body fat percent (WMD: -1.57%, 95%CI: -2.47, -0.68), insulin level (WMD: -2.45 mmol/L; 95%CI: -4.40, -0.49 mmol/L) and HOMA-IR (WMD:-0.65 mmol/L; 95%CI: -0.90, -0.41 mmol/L) in patients with MS, whereas had no effect on glucose, blood pressure and lipids profile. Conclusions: Our findings provide insights into the effect of fasting on the anthropometric outcomes, insulin resistance, and gut microbiota in MS.

Microbiome-Based Therapies in Parkinson's Disease: Can Tuning the Microbiota Become a Viable Therapeutic Strategy?

Progressive neurodegenerative disorders such as Parkinson's disease (PD) have continued to baffle medical science, despite strides in the understanding of their pathology. The inability of currently available therapies to halt disease progression is a testament to an incomplete understanding of pathways crucial to disease initiation, progression and management. Science has continued to link the activities and equilibrium of the gut microbiome to the health and proper functioning of brain neurons. They also continue to stir interest in the potential applications of technologies that may shift the balance of the gut microbiome towards achieving a favourable outcome in PD management. There have been suggestions that an improved understanding of the roles of the gut microbiota is likely to lead to the emergence of an era where their manipulation becomes a recognized strategy for PD management. This review examines the current state of our journey in the quest to understand how the gut microbiota can influence several aspects of PD. We highlight the relationship between the gut microbiome/microbiota and PD pathogenesis, as well as preclinical and clinical evidence evaluating the effect of postbiotics, probiotics and prebiotics in PD management. This is with a view to ascertaining if we are at the threshold of discovering the application of a usable tool in our quest for disease modifying therapies in PD.

Apolipoprotein A-I mimetic peptides (ApoAI MP) improve oxidative stress and inflammatory responses in Parkinson’s disease mice

Purpose: Parkinson’s disease (PD) is closely associated with oxidative stress and inflammatory situation. Apolipoprotein A-I mimetic peptides (ApoAI MP) have antioxidant and anti-inflammatory properties. We aimed to study the therapeutic effect of ApoAI MP on PD mice, and to explore the related mechanisms.

Methods: PD mice were induced by using 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP). The model mice were treated with different concentrations of ApoAI MP. The open-field behavioral test assesses the total distance moved, the rest time, and the number of crossings and Rota-rod was used to evaluate motor coordination. Oxidative stress was identified by measuring the levels of superoxide dismutase (SOD), catalase (CAT), glutathionperoxidase (GSH-Px), malondialdehyde, ROS and H2O2. Inflammatory situation was analyzed by measuring the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Meanwhile, the scavenging activities of ApoAI MP for ABTS, DPPH, hydroxyl radical and superoxide anion, and the effects of the peptide on neurotransmitters were evaluated.

Results: PD model establishment increased oxidative stress and inflammatory status by increasing the concentrations of ROS and H2O2 production, and the levels of TNF-α, IL-1β and IL-6 (p < 0.05). ApoAI MP intervention improved PD symptoms by reducing the total moved distance and the number of passes (p < 0.01), and the falling times from Rota-rod, and increasing rest time (p < 0.05). ApoAI MP increased antioxidant properties by increasing the activities of SOD, CAT and GSH-Px, and reducing MDA concentration (p < 0.05). ApoAI MP addition reduced oxidative stress by scavenging ABTS, DPPH, hydroxyl radicals and superoxide anion and reducing the concentrations of ROS and H2O2 production (p < 0.05). ApoAI MP treatment increased anti-inflammatory capacities by reducing the concentrations of TNF-α, IL-1β and IL-6 (p < 0.05). HPLC analysis showed that the peptide treatment improved neurotransmitters.

Conclusion: ApoAI MP can improve the behavioral performance of PD mice by improving antioxidant and anti-inflammatory capacities.