Microbiota-Brain-Gut Axis and Neurodegenerative Diseases

Melatonin alleviates intestinal injury, neuroinflammation and cognitive dysfunction caused by intestinal ischemia/reperfusion

Intestinal ischemia/reperfusion (I/R) can cause multiple organ damage with extremely high morbidity and mortality. Melatonin has anti-inflammatory, anti-oxidative and anti-apoptotic effects against various diseases. This study aimed to explore whether melatonin had a protective effect against intestinal I/R-induced neuroinflammation and cognitive dysfunction, and investigate its potential mechanisms. In this study, melatonin was administered to the rats with intestinal I/R, then histological changes in intestine and brain (frontal cortex and hippocampal CA1 area) tissues and cognitive function were detected, respectively. The encephaledema and blood-brain barrier (BBB) permeability were observed. Moreover, the alterations of proinflammatory factors (tumor necrosis factor-α, interleukin-6 and interleukin-1β), oxidative response (malondialdehyde, superoxide dismutase, and reactive oxygen species), apoptosis and proteins associated with inflammation,including Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (Myd88) and phosphorylated nuclear factor kappa beta (NF-κB), and apoptosis (cleaved caspase-3) in brain tissues were examined. Furthermore, the expressions of TLR4, Myd88, and microglial activity were observed by multiple immunofluorescence staining. The results showed that intestinal I/R-induced abnormal neurobehavior and cerebral damage were ameliorated after melatonin treatment, which were demonstrated by improved cognitive dysfunction and aggravated histology. Furthermore, melatonin decreased the levels of proinflammatory factors and oxidative stress in plasma, intestine and brain tissues, attenuated apoptotic cell, and inhibited the expressions of related proteins and the immunoreactivity of TLR4 or Myd88 in microglia in brain tissues. These findings showed that melatonin might relieve neuroinflammation and cognitive dysfunction caused by intestinal I/R, which could be, at least partially, related to the inhibition of the TLR4/Myd88 signaling in microglia.

Photoperiod Manipulation Affects Transcriptional Profile of Genes Related to Lipid Metabolism and Apoptosis in Zebrafish (Danio rerio) Larvae: Potential Roles of Gut Microbiota

Gut microbiota plays a fundamental role in maintaining host's health by controlling a wide range of physiological processes. Administration of probiotics and manipulation of photoperiod have been suggested as modulators of microbial composition and are currently undergoing an extensive research in aquaculture as a way to improve health and quality of harvested fish. However, our understanding regarding their effects on physiological processes is still limited. In the present study we investigated whether manipulation of photoperiod and/or probiotic administration was able to alter microbial composition in zebrafish larvae at hatching stage. Our findings show that probiotic does not elicit effects while photoperiod manipulation has a significant impact on microbiota composition. Moreover, we successfully predicted lipid biosynthesis and apoptosis to be modulated by microbial communities undergoing continuous darkness. Interestingly, expression levels of caspase 3 gene (casp3) and lipid-related genes (hnf4a, npc1l1, pparγ, srebf1, agpat4 and fitm2) were found to be significantly overexpressed in dark-exposed larvae, suggesting an increase in the occurrence of apoptotic processes and a lipid metabolism impairment, respectively (p < 0.05). Our results provide the evidence that microbial communities in zebrafish at early life stages are not modulated by a short administration of probiotics and highlight the significant effect that dark photoperiod elicits on zebrafish microbiota and potentially on health.

Recent advances in understanding the mechanisms of PM2.5-mediated neurodegenerative diseases

PM_2.5 particles are widely believed to be associated with respiratory and cardiovascular diseases. However, recent studies have reported that PM_2.5 may be associated with neurodegenerative diseases. The exact mechanism by which PM_2.5 mediates neurotoxicity and cognitive dysfunction is still unclear. In the current work, we collected evidence supporting the association between PM_2.5 exposure and development of neurodegenerative disorders. Evidence from epidemiological investigations, animal experiments, and ex vivo cell experiments showed that PM_2.5 exposure may lead to neuroinflammation, oxidative stress, mitochondrial dysfunction, neuronal apoptosis, synaptic damage and ultimately neurodegenerative diseases.

The Challenge of Antidepressant Therapeutics in Alzheimer's Disease

The link between depression and Alzheimer's disease (AD) is controversial, because it is not clear if depression is an independent risk factor for the disease or a prodromal symptom in the older population. Cerebral amyloid-β (Aβ) peptide deposition is associated with both cognitive symptoms and neuropsychiatric symptoms (NPS), which may be a biological mechanism of compensation. Despite the widespread use of antidepressant therapeutics (30-50% of patients with AD/dementia are on antidepressants), there is mixed evidence regarding the benefits from their use in AD depression. Monoaminergic antidepressant drugs have shown only modest or no clinical benefits. Therefore, it is important to understand the reason of this drug-resistance and the relationship between antidepressant drugs and the Aβ peptide. The goal of the present review is to highlight the etiology of depression in patients affected by AD in comparison to depressive disorders without AD, and to speculate on more appropriate and alternative therapeutics.

The Route to Palatable Fecal Microbiota Transplantation

The community of symbiotic microorganisms that reside in our gastrointestinal tract is integral to human health. Fecal microbiota transplantation (FMT) has been shown to be highly effective in treating recurrent Clostridioides difficile infection (rCDI) and is now recommended by medical societies for patients suffering from rCDI who have failed to respond to conventional therapy. The main challenges with FMT are its accessibility, acceptability, lack of standardization, and regulatory complexity, which will be discussed in this review. Access to FMT is being addressed through the development of frozen and lyophilized FMT preparations that can be prepared at stool banks and shipped to the point of care. Both access and patient acceptance would be enhanced by oral FMT capsules, and there is potential to reduce capsule burden by utilizing colonic release capsules, targeting the site of disease. This review compares the efficacy of different FMT routes of administration: capsules, nasal feeding tubes, enemas, and colonoscopic infusions. FMT is considered investigational by the Food and Drug Administration. In effort to improve access to FMT, physicians may perform FMT outside of an investigational new drug application for treating CDI infections not responsive to standard therapies. The majority of FMT studies report only minor adverse effects; however, there is risk of transmission of infections.

The Controversial Role of Human Gut Lachnospiraceae

The complex polymicrobial composition of human gut microbiota plays a key role in health and disease. Lachnospiraceae belong to the core of gut microbiota, colonizing the intestinal lumen from birth and increasing, in terms of species richness and their relative abundances during the host's life. Although, members of Lachnospiraceae are among the main producers of short-chain fatty acids, different taxa of Lachnospiraceae are also associated with different intra- and extraintestinal diseases. Their impact on the host physiology is often inconsistent across different studies. Here, we discuss changes in Lachnospiraceae abundances according to health and disease. With the aim of harnessing Lachnospiraceae to promote human health, we also analyze how nutrients from the host diet can influence their growth and how their metabolites can, in turn, influence host physiology.

The effect of antibiotics on the gut microbiome: a metagenomics analysis of microbial shift and gut antibiotic resistance in antibiotic treated mice

Background

Emergence of antibiotic resistance is a global public health concern. The relationships between antibiotic use, the gut community composition, normal physiology and metabolism, and individual and public health are still being defined. Shifts in composition of bacteria, antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) after antibiotic treatment are not well-understood.

Methods

This project used next-generation sequencing, custom-built metagenomics pipeline and differential abundance analysis to study the effect of antibiotic monotherapy on resistome and taxonomic composition in the gut of Balb/c mice infected with E. coli via transurethral catheterization to investigate the evolution and emergence of antibiotic resistance.

Results

There is a longitudinal decrease of gut microbiota diversity after antibiotic treatment. Various ARGs are enriched within the gut microbiota despite an overall reduction of the diversity and total amount of bacteria after antibiotic treatment. Sometimes treatment with a specific class of antibiotics selected for ARGs that resist antibiotics of a completely different class (e.g. treatment of ciprofloxacin or fosfomycin selected for cepA that resists ampicillin). Relative abundance of some MGEs increased substantially after antibiotic treatment (e.g. transposases in the ciprofloxacin group).

Conclusions

Antibiotic treatment caused a remarkable reduction in diversity of gut bacterial microbiota but enrichment of certain types of ARGs and MGEs. These results demonstrate an emergence of cross-resistance as well as a profound change in the gut resistome following oral treatment of antibiotics.

Role of Alcohol Drinking in Alzheimer's Disease, Parkinson's Disease, and Amyotrophic Lateral Sclerosis

Neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS), increase as the population ages around the world. Environmental factors also play an important role in most cases. Alcohol consumption exists extensively and it acts as one of the environmental factors that promotes these neurodegenerative diseases. The brain is a major target for the actions of alcohol, and heavy alcohol consumption has long been associated with brain damage. Chronic alcohol intake leads to elevated glutamate-induced excitotoxicity, oxidative stress and permanent neuronal damage associated with malnutrition. The relationship and contributing mechanisms of alcohol with these three diseases are different. Epidemiological studies have reported a reduction in the prevalence of Alzheimer’s disease in individuals who drink low amounts of alcohol; low or moderate concentrations of ethanol protect against β-amyloid (Aβ) toxicity in hippocampal neurons; and excessive amounts of ethanol increase accumulation of Aβ and Tau phosphorylation. Alcohol has been suggested to be either protective of, or not associated with, PD. However, experimental animal studies indicate that chronic heavy alcohol consumption may have dopamine neurotoxic effects through the induction of Cytochrome P450 2E1 (CYP2E1) and an increase in the amount of α-Synuclein (αSYN) relevant to PD. The findings on the association between alcohol consumption and ALS are inconsistent; a recent population-based study suggests that alcohol drinking seems to not influence the risk of developing ALS. Additional research is needed to clarify the potential etiological involvement of alcohol intake in causing or resulting in major neurodegenerative diseases, which will eventually lead to potential therapeutics against these alcoholic neurodegenerative diseases.

Dairy Propionibacterium freudenreichii ameliorates acute colitis by stimulating MUC2 expression in intestinal goblet cell in a DSS-induced colitis rat model

An intact mucus layer is important in managing inflammatory bowel disease (IBD). Dairy Propionibacterium freudenreichii has probiotic potential, produces propionic acid and is known to promote health. The aim of this study was to evaluate the effects of P. freudenreichii on the improvement of colitis. LS 174T goblet cells and a dextran sodium sulfate (DSS)-induced colitis rat model were used to investigate the P. freudenreichii-induced stimulation of mucin production in vitro and in vivo, respectively. The mRNA and protein expression levels of MUC2, a main component of intestinal mucus, increased in the supernatant of P. freudenreichii culture (SPFC)-treated LS 174 cells. The SPFC and live P. freudenreichii (LPF) reduced the disease activity index (DAI) in the rats with DSS-induced colitis. After treatment with SPFC or LPF, the mRNA levels of typical pro-inflammatory cytokines decreased and the inflammatory state was histologically improved in the rats with DSS-induced colitis. The SPFC and LPF treatments increased the gene and protein expression levels of MUC2 in the rats with DSS-induced colitis compared with the expression levels in the negative control rats, and immunohistochemistry (IHC) showed an increase of the intestinal MUC2 level. In addition, SPFC and LPF augmented the level of propionate in the faeces of the rats with DSS-induced colitis. In conclusion, P. freudenreichii might improve acute colitis by restoring goblet cell number and stimulating the expression of MUC2 in intestinal goblet cells.

Volatilomes of Bacterial Infections in Humans

Sense of smell in humans has the capacity to detect certain volatiles from bacterial infections. Our olfactory senses were used in ancient medicine to diagnose diseases in patients. As humans are considered holobionts, each person's unique odor consists of volatile organic compounds (VOCs, volatilome) produced not only by the humans themselves but also by their beneficial and pathogenic micro-habitants. In the past decade it has been well documented that microorganisms (fungi and bacteria) are able to emit a broad range of olfactory active VOCs [summarized in the mVOC database (http://bioinformatics.charite.de/mvoc/)]. During microbial infection, the equilibrium between the human and its microbiome is altered, followed by a change in the volatilome. For several decades, physicians have been trying to utilize these changes in smell composition to develop fast and efficient diagnostic tools, particularly because volatiles detection is non-invasive and non-destructive, which would be a breakthrough in many therapies. Within this review, we discuss bacterial infections including gastrointestinal, respiratory or lung, and blood infections, focusing on the pathogens and their known corresponding volatile biomarkers. Furthermore, we cover the potential role of the human microbiota and their volatilome in certain diseases such as neurodegenerative diseases. We also report on discrete mVOCs that affect humans.

Jiao-tai-wan inhibits inflammation of the gut-brain-axis and attenuates cognitive impairment in insomnic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Jiao-tai-wan is a well-known traditional Chinese herbal medicine formula that is used to treat insomnia and systemic inflammation. Studies indicate chronic insomnia might contribute to the prevalence of cognitive impairment. The role of systemic inflammation and intestinal permeability in the progression of neurodegenerative diseases attracts much attention.

AIM OF THE STUDY

This study aimed to investigate if Jiao-tai-wan plays a role in promoting the repair of the intestinal epithelial barrier to suppress systemic inflammation and cognitive impairment in sleep-deprived (SD) rats.

MATERIALS AND METHODS

Male obesity-resistant SD rats were partially sleep-deprived for 16 weeks. During the last 8 weeks, they were treated with Jiao-tai-wan. A Morris water maze was used to analyze their cognitive ability. Aβ42 and proinflammation cytokines in the cerebrospinal fluid, tissue, or serum were determined using enzyme-linked immunosorbent assay or polymerase chain reaction. Intestinal permeability was detected using the fluorescein isothiocyanate-dextran perfusion assay method. Plasma lipopolysaccharide (LPS) levels were detected with Tachypleus Amebocyte Lysate. Western bolt was used in the signaling pathway analysis.

RESULTS

Sleep deprivation deteriorated the performance of rats in the Morris water maze and increased the Aβ42, caspase3, IL-6, and TNF-α levels in their brains. The intestinal TLR4/NF-κB pathway was activated with an increase in the expression of IL-6 and TNF-α. The expression of tight junction proteins was also decreased in the intestinal tissue. This increased the intestinal permeability and circulation of LPS, LPS binding protein, IL-6, and TNF-α. Treatment with Jiao-tai-wan could partly reverse these changes.

CONCLUSION

Jiao-tai-wan has the potential to attenuate systemic inflammation and cognitive impairment in partially sleep-deprived rats. The possible underlying mechanism is by preventing an inflammation trigger being transferred through the gut-brain-axis.

Gut microbiota and pro/prebiotics in Alzheimer's disease

Alzheimer’s disease is characterized by the accumulation of amyloid and dysfunctional tau protein in the brain along with the final development of dementia. Accumulation of amyloid in the brain was observed 10-20 years before the onset of clinical symptoms by diagnostic methods based on image analysis. This is a serious public health problem, incidence and prevalence being expected to reach epidemic proportions over the next few decades if the disease cannot be prevented or slowed down. Recently, in addition to the strongly developing ischemic etiology of Alzheimer’s disease, it is suggested that the gut microbiota may also participate in the development of this disease. The brain and gut are thought to form a network called the “gut-brain-microbiota axis”, and it is strongly supported idea that the intestinal microflora can be involved in Alzheimer’s disease. Lately, many new studies have been conducted that draw attention to the relationship between Alzheimer’s disease and gut microbiota. This review presents a possible relationship between Alzheimer’s disease and a microbiome. It is a promising idea for prevention or therapeutic intervention. Modulation of the gut microbiota through a personalized diet or beneficial microflora intervention like pro/prebiotics, changing microbiological partners and their products, including amyloid protein, can become a new treatment for Alzheimer’s disease.

Oxidative stress and gut-derived lipopolysaccharides in children affected by paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections

Background

Paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections syndrome (PANDAS) identifies patients with acute onset of obsessive-compulsive and tic disorders. The objective of this study was to evaluate serum NOX2 levels, as well as 8-iso-prostaglandin F2α (8-iso-PGF2α) and lipopolysaccharide (LPS) of PANDAS patients.

Methods

In this study we wanted to compare serum levels of soluble NOX2-dp (sNOX-2-dp), iso-PGF2α and LPS in 60 consecutive subjects, including 30 children affected by PANDAS and 30 controls (CT) matched for age and gender. Serum zonulin was used as intestinal permeability assay.

Results

Compared with CT, PANDAS children had increased serum levels of sNOX-2-dp, 8-iso-PGF2α and LPS. Bivariate analysis showed that serum sNOX2-dp was significantly correlated with LPS (Rs = 0.359; p = 0.005), zonulin (Rs = 0.444; p < 0.001) and 8-iso-PGF2α (Rs = 0.704; p < 0.001). Serum LPS significantly correlated with zonulin (Rs = 0.610; p < 0.001), and 8-iso-PGF2α (Rs = 0.591; p = 0.001). Finally, a multiple linear regression analysis showed that serum 8-iso-PGF2α and zonulin were the only independent variables associated with sNOX2-dp (R² = 68%).

Conclusion

This study shows that children affected by PANDAS have high circulating levels of sNOX2-dp, isoprostanes and of LPS that could be involved in the process of neuroinflammation.

Titanium dioxide nanoparticles via oral exposure leads to adverse disturbance of gut microecology and locomotor activity in adult mice

Titanium dioxide nanoparticles (TiO₂NPs) have been widely used as food additives in daily life. However, the impact of oral intake of TiO₂NPs on the nervous system is largely unknown. In this study, 7-week-old mice were treated with either vehicle or TiO₂NPs suspension solution at 150 mg/kg by intragastric administration for 30 days. Our results demonstrated that oral exposure to TiO₂NPs resulted in aberrant excitement of enteric neurons, although unapparent pathological changes were observed in gut. We also found the richness and evenness of gut microbiota were remarkably decreased and the gut microbial community compositions were significantly changed in the TiO₂NP-treated group as compared with vehicle controls. Interestingly, oral exposure to TiO₂NPs was capable to induce the inhibitory effects on locomotor activity, but it did not lead to significant change on the spatial learning and memory ability. We further revealed the mechanism that TiO₂NPs could specifically cause locomotor dysfunction by elevating the excitement of enteric neuron, which might spread to brain via gut-brain communication by vagal pathway. However, inflammation response, enteric neurotransmitter 5-HT and major gut peptides might not be involved in this pathological process. Together, these findings provide valuable insights into the novel mechanism of TiO₂NP-induced neurotoxicity. Understanding the microbiota-gut-brain axis will provide the foundation for potential therapeutic or prevention approaches against TiO₂NP-induced gut and brain-related disorders.

Gut–Brain Axis: Focus on Neurodegeneration and Mast Cells

Many studies highlighted that a bidirectional communication between the gut and the central nervous system (CNS) exists. A vigorous immune response to antigens must be avoided, and pathogenic organisms crossing the gut barrier must be detected and killed. For this reason, the immune system developed fine mechanisms able to maintain this delicate balance. The microbiota is beneficial to its host, providing protection against pathogenic bacteria. It is intimately involved in numerous aspects of host physiology, from nutritional status to behavior and stress response. In the last few years, the implication of the gut microbiota and its bioactive microbiota-derived molecules in the progression of multiple diseases, as well as in the development of neurodegenerative disorders, gained increasing attention. The purpose of this review is to provide an overview of the gut microbiota with particular attention toward neurological disorders and mast cells. Relevant roles are played by the mast cells in neuroimmune communication, such as sensors and effectors of cytokines and neurotransmitters. In this context, the intake of beneficial bacterial strains as probiotics could represent a valuable therapeutic approach to adopt in combination with classical therapies. Further studies need to be performed to understand if the gut bacteria are responsible for neurological disorders or if neurological disorders influence the bacterial profile.

Manipulating Gut Microbiota Composition to Enhance the Therapeutic Effect of Cancer Immunotherapy

In the past decade, a growing set of immunotherapies including immune checkpoint blockade, chimeric antigen receptor T cells, and bispecific antibodies propelled the advancement of oncology therapeutics. Accumulating evidence demonstrates that immunotherapy could eliminate tumors better than traditional chemotherapy or radiotherapy with lower risk of adverse events in numerous cancer types. Unfortunately, a substantial proportion of patients eventually acquire resistance to immunotherapy. By analyzing the differences between immunotherapy-sensitive and immunotherapy-resistant populations, it was noticed that the composition of gut microbiota is closely related to treatment effect. Moreover, in xenograft models, interventional regulation of gut microbiota could effectively enhance efficacy and relieve resistance during immunotherapy. Thus, we believe that gut microbiota composition might be helpful to explain the heterogeneity of treatment effect, and manipulating gut microbiota could be a promising adjuvant treatment for cancer immunotherapy. In this mini review, we focus on the latest understanding of the cross-talk between gut microbiota and host immunity. Moreover, we highlight the role of gut microbiota in cancer immunotherapy including immune checkpoint inhibitor and adoptive cell transfer.

Impact of Clostridium Bacteria in Children with Autism Spectrum Disorder and Their Anthropometric Measurements

Current research has shown that gut microbiota may play a fundamental role in neurological activity, behavior, mood, cognition, and possibly for the onset as well as the severity of autism spectrum disorder (ASD). Previous studies emphasized the possible correlation between Clostridium spp., gut colonization, and possible development or exacerbating of ASD in affected children. The aim of the present study was to investigate how Clostridia gut colonization can have an impact on the neurological outcome and anthropometric values in ASD children. The present study included 60 children (30 ASD and 30 neurotypical controls) of both sexes aged from 2 to 8 years. Children with ASD were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), Autism Diagnostic Interview-Revised (ADI-R), as well as the Childhood Autism Rating Scale (CARS). Quantitative real-time polymerase chain reaction (real-time PCR) was used to determine Clostridium presence in the stools of the enrolled subjects. The number of Clostridium spp. (Clostridium paraputri, Clostridium bolteae, and Clostridium perfringens) found in the stools of ASD children was greater than neurotypical children. Children with ASD had two types of Clostridium (Clostridium diffiicile and Clostridium clostridiioforme) not found in neurotypical children, whereas neurotypical children yielded only one species (Clostridium tertium) not found in the ASD children. The present study emphasizes the potential correlation between gut colonization of Clostridia and the probability of developing or exacerbating ASD among Egyptian children. If Clostridium bacteria play a potential role in the etiology of ASD, this may open the possibility for effective treatment of these patients.

Association of oral dysbiosis with oral cancer development

Oral squamous cell carcinoma (OSCC) is the leading cause of mortality for oral cancer. Numerous risk factors mainly related to unhealthy habits and responsible for chronic inflammation and infections have been recognized as predisposing factors for oral carcinogenesis. Recently, even microbiota alterations have been associated with the development of human cancers. In particular, some specific bacterial strains have been recognized and strongly associated with oral cancer development (Capnocytophaga gingivalis, Fusobacterium spp., Streptococcus spp., Peptostreptococcus spp., Porphyromonas gingivalis and Prevotella spp.). Several hypotheses have been proposed to explain how the oral microbiota could be involved in cancer pathogenesis by mainly paying attention to chronic inflammation, microbial synthesis of cancerogenic substances, and alteration of epithelial barrier integrity. Based on knowledge of the carcinogenic effects of dysbiosis, it was recently suggested that probiotics may have anti-tumoral activity. Nevertheless, few data exist with regard to probiotic effects on oral cancer. On this basis, the association between the development of oral cancer and oral dysbiosis is discussed focusing attention on the potential benefits of probiotics administration in cancer prevention.

Is the gut microbiota dysbiotic in patients with classical homocystinuria?

Classical homocystinuria (HCU) is characterized by increased plasma levels of total homocysteine (tHcy) and methionine (Met). Treatment may involve supplementation of B vitamins and essential amino acids, as well as restricted Met intake. Dysbiosis has been described in some inborn errors of metabolism, but has not been investigated in HCU. The aim of this study was to investigate the gut microbiota of HCU patients on treatment. Six unrelated HCU patients (males = 5, median age = 25.5 years) and six age-and-sex-matched healthy controls (males = 5, median age = 24.5 years) had their fecal microbiota characterized through partial 16S rRNA gene sequencing. Fecal pH, a 3-day dietary record, medical history, and current medications were recorded for both groups. All patients were nonresponsive to pyridoxine and were on a Met-restricted diet and presented with high tHcy. Oral supplementation of folate (n = 6) and pyridoxine (n = 5), oral intake of betaine (n = 4), and IM vitamin B12 supplementation (n = 4), were reported only in the HCU group. Patients had decreased daily intake of fat, cholesterol, vitamin D, and selenium compared to controls (p < 0.05). There was no difference in alpha and beta diversity between the groups. HCU patients had overrepresentation of the Eubacterium coprostanoligenes group and underrepresentation of the Alistipes, Family XIII UCG-001, and Parabacteroidetes genera. HCU patients and controls had similar gut microbiota diversity, despite differential abundance of some bacterial genera. Diet, betaine, vitamin B supplementation, and host genetics may contribute to these differences in microbial ecology.

The Relationship Between the Serotonin Metabolism, Gut-Microbiota and the Gut-Brain Axis

BACKGROUND

Serotonin (5-HT) has a pleiotropic function in gastrointestinal, neurological/psychiatric and liver diseases. The aim of this review was to elucidate whether the gut-microbiota played a critical role in regulating peripheral serotonin levels.

METHODS

We searched for relevant studies published in English using the PubMed database from 1993 to the present.

RESULTS

Several studies suggested that alterations in the gut-microbiota may contribute to a modulation of serotonin signalling. The first indication regarded the changes in the composition of the commensal bacteria and the intestinal transit time caused by antibiotic treatment. The second indication regarded the changes in serotonin levels correlated to specific bacteria. The third indication regarded the fact that decreased serotonin transporter expression was associated with a shift in gut-microbiota from homeostasis to inflammatory type microbiota. Serotonin plays a key role in the regulation of visceral pain, secretion, and initiation of the peristaltic reflex; however, its altered levels are also detected in many different psychiatric disorders. Symptoms of some gastrointestinal functional disorders may be due to deregulation in central nervous system activity, dysregulation at the peripheral level (intestine), or a combination of both (brain-gut axis) by means of neuro-endocrine-immune stimuli. Moreover, several studies have demonstrated the profibrogenic role of 5-HT in the liver, showing that it works synergistically with platelet-derived growth factor in stimulating hepatic stellate cell proliferation.

CONCLUSION

Although the specific interaction mechanisms are still unclear, some studies have suggested that there is a correlation between the gut-microbiota, some gastrointestinal and liver diseases and the serotonin metabolism.

Small Vessel Disease-Related Dementia: An Invalid Neurovascular Coupling?

The arteriosclerosis-dependent alteration of brain perfusion is one of the major determinants in small vessel disease, since small vessels have a pivotal role in the brain's autoregulation. Nevertheless, as far as we know, endothelium distress can potentiate the flow dysregulation and lead to subcortical vascular dementia that is related to small vessel disease (SVD), also being defined as subcortical vascular dementia (sVAD), as well as microglia activation, chronic hypoxia and hypoperfusion, vessel-tone dysregulation, altered astrocytes, and pericytes functioning blood-brain barrier disruption. The molecular basis of this pathology remains controversial. The apparent consequence (or a first event, too) is the macroscopic alteration of the neurovascular coupling. Here, we examined the possible mechanisms that lead a healthy aging process towards subcortical dementia. We remarked that SVD and white matter abnormalities related to age could be accelerated and potentiated by different vascular risk factors. Vascular function changes can be heavily influenced by genetic and epigenetic factors, which are, to the best of our knowledge, mostly unknown. Metabolic demands, active neurovascular coupling, correct glymphatic process, and adequate oxidative and inflammatory responses could be bulwarks in defense of the correct aging process; their impairments lead to a potentially catastrophic and non-reversible condition.

Oxidative Stress and Gut-Derived Lipopolysaccharides in Neurodegenerative Disease: Role of NOX2

Background

Neurodegenerative diseases (ND) as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis represent a growing cause of disability in the developed countries. The underlying physiopathology is still unclear. Several lines of evidence suggest a role for oxidative stress and NADPH oxidase 2 (NOX2) in the neuropathological pathways that lead to ND. Furthermore, recent studies hypothesized a role for gut microbiota in the neuroinflammation; in particular, lipopolysaccharide (LPS) derived from Gram-negative bacteria in the gut is believed to play a role in causing ND by increase of oxidative stress and inflammation. The aim of this study was to assess NOX2 activity as well as serum 8-iso-prostaglandin F2α (8-iso-PGF2α (8-iso-PGF2

Methods

One hundred and twenty-eight consecutive subjects, including 64 ND patients and 64 controls (CT) matched for age and gender, were recruited. A cross-sectional study was performed to compare serum activity of soluble NOX2-dp (sNOX2-dp), blood levels of isoprostanes, serum H₂O₂, and LPS in these two groups. Serum zonulin was used to assess gut permeability.

Results

Compared with CT, ND patients had higher values of sNOX2-dp, 8-iso-PGF2α (8-iso-PGF2p < 0.001), zonulin (Rs = 0.411; p < 0.001), zonulin (Rs = 0.411; p < 0.001), zonulin (Rs = 0.411; α (8-iso-PGF2p < 0.001), zonulin (Rs = 0.411; p < 0.001), zonulin (Rs = 0.411; α (8-iso-PGF2p < 0.001), zonulin (Rs = 0.411; β, 0.459; p < 0.001), zonulin (Rs = 0.411; α (8-iso-PGF2β, 0.459; p < 0.001), zonulin (Rs = 0.411; R² = 57%).

Conclusion

This study provides the first report attesting that patients with ND have high NOX2 activation that could be potentially implicated in the process of neuroinflammation.

Recent advances in modulating the microbiome

We are in the midst of “the microbiome revolution”—not a day goes by without some new revelation on the potential role of the gut microbiome in some disease or disorder. From an ever-increasing recognition of the many roles of the gut microbiome in health and disease comes the expectation that its modulation could treat or prevent these very same diseases. A variety of interventions could, at least in theory, be employed to alter the composition or functional capacity of the microbiome, ranging from diet to fecal microbiota transplantation (FMT). For some, such as antibiotics, prebiotics, and probiotics, an extensive, albeit far from consistent, literature already exists; for others, such as other dietary supplements and FMT, high-quality clinical studies are still relatively few in number. Not surprisingly, researchers have turned to the microbiome itself as a source for new entities that could be used therapeutically to manipulate the microbiome; for example, some probiotic strains currently in use were sourced from the gastrointestinal tract of healthy humans. From all of the extant studies of interventions targeted at the gut microbiome, a number of important themes have emerged. First, with relatively few exceptions, we are still a long way from a precise definition of the role of the gut microbiome in many of the diseases where a disturbed microbiome has been described—association does not prove causation. Second, while animal models can provide fascinating insights into microbiota–host interactions, they rarely recapitulate the complete human phenotype. Third, studies of several interventions have been difficult to interpret because of variations in study population, test product, and outcome measures, not to mention limitations in study design. The goal of microbiome modulation is a laudable one, but we need to define our targets, refine our interventions, and agree on outcomes.

Anesthesia and surgery induce age-dependent changes in behaviors and microbiota

The neuropathogenesis of postoperative delirium remains mostly unknown. The gut microbiota is implicated in the pathogenesis of neurological disorders. We, therefore, set out to determine whether anesthesia/surgery causes age-dependent gut microbiota dysbiosis, changes in brain IL-6 level and mitochondrial function, leading to postoperative delirium-like behavior in mice. Female 9 or 18 months old mice received abdominal surgery under 1.4% isoflurane for two hours. The postoperative delirium-like behavior, gut microbiota, levels of brain IL-6, PSD-95 and synaptophysin, and mitochondrial function were determined by a battery of behavioral tests, 16s rRNA sequencing, ELISA, Western blot and Seahorse XFp Extracellular Flux Analyzer. Intragastric administration of Lactobacillus (10 days) and probiotic (20 days) were used to mitigate the anesthesia/surgery-induced changes. Anesthesia/surgery caused different alterations in gut microbiota, including change rate of reduction in the levels of gut lactobacillus, between the 18 and 9 months old mice. The anesthesia/surgery induced greater postoperative delirium-like behavior, increased brain IL-6 levels, decreased PSD-95 and synaptophysin levels, and mitochondrial dysfunction in 18 than 9 months old mice. Treatments with Lactobacillus and probiotic mitigated the anesthesia/surgery-induced changes. These data suggest that microbiota dysbiosis may contribute to neuropathogenesis of postoperative delirium and treatment with Lactobacillus or a probiotic could mitigate postoperative delirium.

Chronic periodontitis induces microbiota-gut-brain axis disorders and cognitive impairment in mice

Epidemiological studies suggest that chronic periodontitis (CP) is closely associated with the incidence and progression of cognitive impairment. The present study investigated the causal relationship between CP and cognitive decline and the underlying mechanism in mice. Long-term ligature around the left second maxillary molar tooth was used to induce CP in mice. Severe alveolar bone loss and inflammatory changes were observed in gingival tissues, accompanied by progressive cognitive deficits during a 12-month period. We also observed cerebral neuronal and synaptic injury and glial activation in this mouse model of CP. Furthermore, CP mice exhibited significant dysbiosis of the oral and gut microbiota, disruption of the intestinal barrier and blood-brain barrier, increases in the serum contents of proinflammatory cytokines and lipopolysaccharide (LPS), and increases in brain LPS levels, Toll-like receptor 4 (TLR4) expression, nuclear factor-κB (NF-κB) nuclear translocation and proinflammatory cytokine mRNA levels. These results indicate that CP may directly induce progressive cognitive decline and its mechanism is probably related to microbiota-gut-brain axis disorders, LPS/TLR4/NF-κB signaling activation and neuroinflammatory responses in mice. Therefore, the microbiota-gut-brain axis may provide the potential strategy for the prevention and treatment of CP-associated cognitive impairment.

Gut microbiota compositional profile and serum metabolic phenotype in patients with primary open-angle glaucoma

The gut microbiota (GM) and its influence on host metabolism are considered to be an environmental factor that contributes to the progression of many immune and neurodegenerative diseases. However, the features of the GM and serum metabolites in Primary open-angle glaucoma (POAG) patients have not been clearly elucidated. The purpose of this research is to explore the gut microbial composition and serum metabolic phenotype in POAG patients. 16S rRNA V4 genes of bacteria from the fecal samples of 30 POAG patients and 30 healthy subjects were sequenced by the Illumina MiSeq platform and then analyzed by QIIME. Their serum samples were analyzed by gas chromatography/mass spectrometry (GC-MS)-based metabolomics. The association between gut microbial species and host circulating metabolites and clinical phenotypes was also analyzed. Compared with controls, f Prevotellaceae, g unidentified Enterobacteriaceae, and s Escherichia coli increased the most in POAG patients, whereas g Megamonas and s Bacteroides plebeius significantly decreased in POAG patients. The alteration of the endogenous metabolomic profile in POAG patients included five amino acids or dipeptides, two hormone derivates, one purine derivative, one bile acid derivative and one organic acid. It also showed that citric acid was positively correlated with Megamonas, whereas L-γ-Glutamyl-L-alanine, MHPG, cholic acid glucuronide and hypoxanthine were negatively correlated with Megamonas. Mean visual acuity was negatively correlated with Blautia, mean VF-MD was negatively correlated with Faecalibacterium, and average RNFL thickness was positively correlated with Streptococcus. Our results revealed that there was a distinct difference in GM composition and serum metabolic phenotype between POAG patients and healthy individuals. This finding suggests the potential correlations between the GM and serum metabolites in the pathogenesis of glaucoma and thus provides new insight into the GM-targeted interventions of this disease.

CircNF1-419 improves the gut microbiome structure and function in AD-like mice

Our pre-experiments found that the brain circRNA sequence profiles and gut microbiota in AD-like mice were changed, as circNF1-419 could enhance autophagy to ameliorate senile dementia in AD-like mice, so we conclude that there might some connections between circRNA and gut microbiome. Therefore, we use the over-expressed circNF1-419 adeno-associated virus (AAV) animal system with the aim of identifying possible connections. Our results showed that over-expression of circNF1-419 in brain not only influenced the cholinergic system of brain, but also changed the gut microbiota composition as the Candidatus Arthromitus, Lachnospiraceae FCS020 group, Lachnospiraceae UCG-006, and [Eubacterium] xylanophilum group, and the intestinal homeostasis and physiology, and even the gut microbiota trajectory in new born mice. These findings demonstrate a link between circRNA and gut microbiome, enlarge the 'microbiome- transcriptome' linkage library and provide more information on gut-brain axis.

Post-stroke remodeling processes in animal models and humans

After cerebral ischemia, events like neural plasticity and tissue reorganization intervene in lesioned and non-lesioned areas of the brain. These processes are tightly related to functional improvement and successful rehabilitation in patients. Plastic remodeling in the brain is associated with limited spontaneous functional recovery in patients. Improvement depends on the initial deficit, size, nature and localization of the infarction, together with the sex and age of the patient, all of them affecting the favorable outcome of reorganization and repair of damaged areas. A better understanding of cerebral plasticity is pivotal to design effective therapeutic strategies. Experimental models and clinical studies have fueled the current understanding of the cellular and molecular processes responsible for plastic remodeling. In this review, we describe the known mechanisms, in patients and animal models, underlying cerebral reorganization and contributing to functional recovery after ischemic stroke. We also discuss the manipulations and therapies that can stimulate neural plasticity. We finally explore a new topic in the field of ischemic stroke pathophysiology, namely the brain-gut axis.

The role of gut microbiota, butyrate and proton pump inhibitors in amyotrophic lateral sclerosis: a systematic review

Aim of the study: We conducted a systematic review on existing literature in humans and animals, linking the gut microbiome with amyotrophic lateral sclerosis (ALS). Additionally, we sought to explore the role of the bacterially produced metabolite butyrate as well as of proton pump inhibitors (PPIs) in these associations.Materials and methods: Following PRISMA guidelines for systematic literature reviews, four databases (Medline, Scopus, Embase and Web of Science) were searched and screened by two independent reviewers against defined inclusion criteria. Six studies in humans and six animal studies were identified, summarized and reviewed.Results: Overall, the evidence accrued to date is supportive of changes in the gut microbiome being associated with ALS risk, and potentially progression, though observational studies are small (describing a total of 145 patients with ALS across all published studies), and not entirely conclusive.Conclusions: With emerging studies beginning to apply metagenome sequencing, more clarity regarding the importance and promise of the gut microbiome in ALS can be expected. Future studies may also help establish the therapeutic potential of butyrate, and the role of PPIs in these associations.

Detrimental and protective action of microglial extracellular vesicles on myelin lesions: astrocyte involvement in remyelination failure

Microglia are highly plastic immune cells which exist in a continuum of activation states. By shaping the function of oligodendrocyte precursor cells (OPCs), the brain cells which differentiate to myelin-forming cells, microglia participate in both myelin injury and remyelination during multiple sclerosis. However, the mode(s) of action of microglia in supporting or inhibiting myelin repair is still largely unclear. Here, we analysed the effects of extracellular vesicles (EVs) produced in vitro by either pro-inflammatory or pro-regenerative microglia on OPCs at demyelinated lesions caused by lysolecithin injection in the mouse corpus callosum. Immunolabelling for myelin proteins and electron microscopy showed that EVs released by pro-inflammatory microglia blocked remyelination, whereas EVs produced by microglia co-cultured with immunosuppressive mesenchymal stem cells promoted OPC recruitment and myelin repair. The molecular mechanisms responsible for the harmful and beneficial EV actions were dissected in primary OPC cultures. By exposing OPCs, cultured either alone or with astrocytes, to inflammatory EVs, we observed a blockade of OPC maturation only in the presence of astrocytes, implicating these cells in remyelination failure. Biochemical fractionation revealed that astrocytes may be converted into harmful cells by the inflammatory EV cargo, as indicated by immunohistochemical and qPCR analyses, whereas surface lipid components of EVs promote OPC migration and/or differentiation, linking EV lipids to myelin repair. Although the mechanisms through which the lipid species enhance OPC maturation still remain to be fully defined, we provide the first demonstration that vesicular sphingosine 1 phosphate stimulates OPC migration, the first fundamental step in myelin repair. From this study, microglial EVs emerge as multimodal and multitarget signalling mediators able to influence both OPCs and astrocytes around myelin lesions, which may be exploited to develop novel approaches for myelin repair not only in multiple sclerosis, but also in neurological and neuropsychiatric diseases characterized by demyelination.

Microbiota impacts on chronic inflammation and metabolic syndrome - related cognitive dysfunction

Cognitive dysfunction, one of the major concerns of increased life expectancy, is prevalent in patients with metabolic disorders. Added to the inflammation in the context of aging (inflammaging), low-grade chronic inflammation (metaflammation) accompanies metabolic diseases. Peripheral and central inflammation underlie metabolic syndrome - related cognitive dysfunction. The gut microbiota is increasingly recognized to be linked to both inflammaging and metaflammation in parallel to the pathophysiology of obesity, type 2 diabetes and the metabolic syndrome. Microbiota composition, diversity and diverse metabolites have been related to different metabolic features and cognitive traits. The study of different mouse models has contributed to identify characteristic microbiota profiles and shifts in the microbial gene richness in association with cognitive function. Diet, exercise and prebiotics, probiotics or symbiotics significantly influence cognition and changes in the microbiota. Few studies have analyzed the gut microbiota composition in association with cognitive function in humans. Impaired attention, mental flexibility and executive function have been observed in association with a microbiota ecosystem in cross-sectional and longitudinal studies. Nevertheless, the evidence in humans is still scarce and not causal relationships may be inferred, so larger and long-term studies are required to gain insight into the possible role of microbiota in human cognition.

Keto microbiota: A powerful contributor to host disease recovery

Gut microbiota (GM) is a key contributor to host metabolism and physiology. Data generated on comparing diseased and healthy subjects have reported changes in the GM profile between both health states, suggesting certain bacterial composition could be involved in pathogenesis. Moreover, studies reported that reshaping of GM could contribute actively to disease recovery. Interestingly, ketogenic diets (KD) have emerged recently as new economic dietotherapeutic strategy to combat a myriad of diseases (refractory epilepsy, obesity, cancer, neurodegenerative diseases…). KD, understood in a broad sense, refers to whatever dietetic approximation, which causes physiological ketosis. Therefore, high fat-low carbs diets, fasting periods or caloric restriction constitute different strategies to produce an increase of main ketones bodies, acetoacetate and β-hydroxybutyrate, in blood. Involved biological mechanisms in ketotherapeutic effects are still to be unravelled. However, it has been pointed out that GM remodelling by KD, from now on "keto microbiota", may play a crucial role in patient response to KD treatment. In fact, germ-free animals were resistant to ketotherapeutic effects; reinforcing keto microbiota may be a powerful contributor to host disease recovery. In this review, we will comment the influence of gut microbiota on host, as well as, therapeutic potential of ketogenic diets and keto microbiota to restore health status. Current progress and limitations will be argued too. In spite of few studies have defined applicability and mechanisms of KD, in the light of results, keto microbiota might be a new useful therapeutic agent.

The Gut Microbiota Links Dietary Polyphenols With Management of Psychiatric Mood Disorders

The pathophysiology of depression is multifactorial yet generally aggravated by stress and its associated physiological consequences. To effectively treat these diverse risk factors, a broad acting strategy is required and is has been suggested that gut-brain-axis signaling may play a pinnacle role in promoting resilience to several of these stress-induced changes including pathogenic load, inflammation, HPA-axis activation, oxidative stress and neurotransmitter imbalances. The gut microbiota also manages the bioaccessibility of phenolic metabolites from dietary polyphenols whose multiple beneficial properties have known therapeutic efficacy against depression. Although several potential therapeutic mechanisms of dietary polyphenols toward establishing cognitive resilience to neuropsychiatric disorders have been established, only a handful of studies have systematically identified how the interaction of the gut microbiota with dietary polyphenols can synergistically alleviate the biological signatures of depression. The current review investigates several of these potential mechanisms and how synbiotics, that combine probiotics with dietary polyphenols, may provide a novel therapeutic strategy for depression. In particular, synbiotics have the potential to alleviate neuroinflammation by modulating microglial and inflammasome activation, reduce oxidative stress and balance serotonin metabolism therefore simultaneously targeting several of the major pathological risk factors of depression. Overall, synbiotics may act as a novel therapeutic paradigm for neuropsychiatric disorders and further understanding the fundamental mechanisms of gut-brain-axis signaling will allow full utilization of the gut microbiota's as a therapeutic tool.

The Gut Microbiome and Mental Health: What Should We Tell Our Patients?: Le microbiote Intestinal et la Santé Mentale : que Devrions-Nous dire à nos Patients?

The gut microbiome as a potential therapeutic target for mental illness is a hot topic in psychiatry. Trillions of bacteria reside in the human gut and have been shown to play a crucial role in gut-brain communication through an influence on neural, immune, and endocrine pathways. Patients with various psychiatric disorders including depression, bipolar disorder, schizophrenia, and autism spectrum disorder have been shown to have significant differences in the composition of their gut microbiome. Enhancing beneficial bacteria in the gut, for example, through the use of probiotics, prebiotics, or dietary change, has the potential to improve mood and reduce anxiety in both healthy people and patient groups. Much attention is being given to this subject in the general media, and patients are becoming increasingly interested in the potential to treat mental illness with microbiome-based therapies. It is imperative that those working with people with mental illness are aware of the rationale and current evidence base for such treatment strategies. In this review, we provide an overview of the gut microbiome, what it is, and what it does in relation to gut-brain communication and psychological function. We describe the fundamental principles and basic techniques used in microbiome-gut-brain axis research in an accessible way for a clinician audience. We summarize the current evidence in relation to microbiome-based strategies for various psychiatric disorders and provide some practical advice that can be given to patients seeking to try a probiotic for mental health benefit.

Gut Vibes in Parkinson's Disease: The Microbiota-Gut-Brain Axis

Background

The complexity of the pathogenic mechanisms underlying neurodegenerative disorders such as Parkinson's disease (PD) is attributable to multifactorial changes occurring at a molecular level, influenced by genetics and environmental interactions. However, what causes the main hallmarks of PD is not well understood. Recent data increasingly suggest that imbalances in the gut microbiome composition might trigger and/or exacerbate the progression of PD.

Objective

The present review aims to (1) report emerging literature showing changes in microbiota composition of PD patients compared to healthy individuals and (2) discuss how these changes may initiate and/or perpetuate PD pathology.

Methods

We analyzed 13 studies published from 2015 and included in this review. Altered microbial taxa were compiled in a detailed table summarizing bacterial changes in fecal/mucosal samples. The methodology was systematically reviewed across the articles and was also included in a table to facilitate comparisons between studies.

Results

Multiple studies found a reduction in short-chain fatty-acid-producing bacteria that can rescue neuronal damage through epigenetic mechanisms. Overall, the studies showed that changes in the gut microbiota composition might influence colonic inflammation, gut permeability, and α-synuclein aggregation, contributing to the neurogenerative process.

Conclusion

Further studies with larger cohorts and high-resolution sequencing methods are required to better define gut microbiota changes in PD. Furthermore, additional longitudinal studies are required to determine the causal link between these changes and PD pathogenesis as well as to study the potential of the intestinal microbiota as a biomarker.

Gut DNA Virome Diversity and Its Association with Host Bacteria Regulate Inflammatory Phenotype and Neuronal Immunotoxicity in Experimental Gulf War Illness

Gulf War illness (GWI) is characterized by the persistence of inflammatory bowel disease, chronic fatigue, neuroinflammation, headache, cognitive impairment, and other medically unexplained conditions. Results using a murine model show that enteric viral populations especially bacteriophages were altered in GWI. The increased viral richness and alpha diversity correlated positively with gut bacterial dysbiosis and proinflammatory cytokines. Altered virome signature in GWI mice also had a concomitant weakening of intestinal epithelial tight junctions with a significant increase in Claudin-2 protein expression and decrease in ZO1 and Occludin mRNA expression. The altered virome signature in GWI, decreased tight junction protein level was followed by the presence an activation of innate immune responses such as increased Toll-like receptor (TLR) signaling pathways. The altered virome diversity had a positive correlation with serum IL-6, IL-1β, and IFN-γ, intestinal inflammation (IFN-γ), and decreased Brain-Derived Neurotrophic Factor (BDNF), a neurogenesis marker. The co-exposure of Gulf War chemical and antibiotic (for gut sterility) or Gulf War chemical and Ribavirin, an antiviral compound to suppress virus alteration in the gut showed significant improvement in epithelial tight junction protein, decreased intestinal-, systemic-, and neuroinflammation. These results showed that the observed enteric viral dysbiosis could activate enteric viral particle-induced innate immune response in GWI and could be a novel therapeutic target in GWI.

Fecal Calprotectin as a Marker of the Gut Immune System Activation Is Elevated in Parkinson's Disease

Introduction

Alpha-synucleinopathy constituting a characteristic feature of Parkinson’s disease (PD) occurs at all levels of the brain-gut axis including the enteric nervous system (ENS). Lesions in the ENS may be connected with gut inflammation, increased intestinal permeability and dysmotility contributing to the pathogenesis of PD and its gastrointestinal manifestations.

Aims

To evaluate fecal calprotectin and zonulin as biomarkers of gut inflammation and intestinal barrier dysfunction in PD patients.

Methods

Quantitative evaluation of fecal biomarkers was performed by ELISA tests in 35 PD patients and 20 healthy controls. Additionally, patients filled out a short questionnaire concerning gastrointestinal symptoms.

Results

Median fecal calprotectin level (μg/g) was significantly higher in PD patients compared to the controls: 54.5 (29.0–137.9) vs. 9.7 (5.2–23.3), p < 0.0001. Applying age-related reference ranges, the increased fecal calprotectin level was found in 43% of PD patients and in none of the control subjects (p < 0.001). No correlation between fecal calprotectin level and PD duration was observed. No statistically significant difference between the groups regarding zonulin level was found. The most frequent bowel symptoms reported by PD patients included constipation (69% of subjects), feeling of incomplete evacuation (51%), bloating (51%), abdominal pain (20%), and alternating bowel movement pattern (17%).

Conclusion

The evaluation of fecal calprotectin level may be a useful tool to detect the signs of gut immune system activation present in a remarkable number of PD patients, also in the early stage of the disease. Calprotectin may constitute a critical link between amyloid formation and neuroinflammatory cascades serving as a prospective diagnostic and therapeutic target.

TREM Receptors Connecting Bowel Inflammation to Neurodegenerative Disorders

Alterations in Triggering Receptors Expressed on Myeloid cells (TREM-1/2) are bound to a variety of infectious, sterile inflammatory, and degenerative conditions, ranging from inflammatory bowel disease (IBD) to neurodegenerative disorders. TREMs are emerging as key players in pivotal mechanisms often concurring in IBD and neurodegeneration, namely microbiota dysbiosis, leaky gut, and inflammation. In conditions of dysbiosis, compounds released by intestinal bacteria activate TREMs on macrophages, leading to an exuberant pro-inflammatory reaction up to damage in the gut barrier. In turn, TREM-positive activated macrophages along with inflammatory mediators may reach the brain through the blood, glymphatic system, circumventricular organs, or the vagus nerve via the microbiota-gut-brain axis. This leads to a systemic inflammatory response which, in turn, impairs the blood-brain barrier, while promoting further TREM-dependent neuroinflammation and, ultimately, neural injury. Nonetheless, controversial results still exist on the role of TREM-2 compared with TREM-1, depending on disease specificity, stage, and degree of inflammation. Therefore, the present review aimed to provide an update on the role of TREMs in the pathophysiology of IBD and neurodegeneration. The evidence here discussed the highlights of the potential role of TREMs, especially TREM-1, in bridging inflammatory processes in intestinal and neurodegenerative disorders.

FETR-ALS Study Protocol: A Randomized Clinical Trial of Fecal Microbiota Transplantation in Amyotrophic Lateral Sclerosis

Background and Rationale: Among the key players in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS), microglia and T regulatory lymphocytes (Treg) are candidate cells for modifying the course of the disease. The gut microbiota (GM) acts by shaping immune tolerance and regulating the Treg number and suppressive function, besides circulating neuropeptides, and other immune cells that play in concert through the gut-brain axis. Previous mouse models have shown an altered enteric flora in early stage ALS, pointing to a possible GM role in ALS pathogenesis. Fecal Microbial Transplantation (FMT) is a well-known therapeutic intervention used to re-establish the proper microenvironment and to modulate enteric and systemic immunity.

Methods: We are going to perform a multicenter randomized double-blind clinical trial employing FMT as a therapeutic intervention for ALS patients (NCT0376632). Forty-two ALS patients, at an early stage, will be enrolled with a 2:1 allocation ratio (28 FMT-treated patients vs. 14 controls). Study duration will be 12 months per patient. Three endoscopic procedures for intestinal biopsies in FMT and control groups are predicted at baseline, month 6 and month 12; at baseline and at month 6 fresh feces from healthy donors will be infused at patients in the intervention arm. The primary outcome is a significant change in Treg number between FMT-treated patients and control arm from baseline to month 6. Secondary outcomes include specific biological aims, involving in-depth analysis of immune cells and inflammatory status changes, central and peripheral biomarkers of ALS, besides comprehensive analysis of the gut, saliva and fecal microbiota. Other secondary aims include validated clinical outcomes of ALS (survival, forced vital capacity, and modifications in ALSFRS-R), besides safety and quality of life.

Expected Results: We await FMT to increase Treg number and suppressive functionality, switching the immune system surrounding motorneurons to an anti-inflammatory, neuroprotective status. Extensive analysis on immune cell populations, cytokines levels, and microbiota (gut, fecal and saliva) will shed light on early processes possibly leading the degenerative ALS course.

Conclusions: This is the first trial with FMT as a potential intervention to modify immunological response to ALS and disease progression at an early stage.

A New Integrative Theory of Brain-Body-Ecosystem Medicine: From the Hippocratic Holistic View of Medicine to Our Modern Society

Humans are increasingly aware that their fate will depend on the wisdom they apply in interacting with the ecosystem. Its health is defined as the condition in which the ecosystem can deliver and continuously renew its fundamental services. A healthy ecosystem allows optimal interactions between humans and the other biotic/abiotic components, and only in a healthy ecosystem can humans survive and efficiently reproduce. Thus, both the human and ecosystem health should be considered together in view of their interdependence. The present article suggests that this relationship could be considered starting from the Hippocrates (460 BC-370 BC) work "On Airs, Waters, and Places" to derive useful medical and philosophical implications for medicine which is indeed a topic that involves scientific as well as philosophical concepts that implicate a background broader than the human body. The brain-body-ecosystem medicine is proposed as a new more complete approach to safeguarding human health. Epidemiological data demonstrate that exploitation of the environment resulting in ecosystem damage affects human health and in several instances these diseases can be detected by modifications in the heart-brain interactions that can be diagnosed through the analysis of changes in heart rate variability.

Mild cognitive impairment has similar alterations as Alzheimer's disease in gut microbiota

OBJECTIVE

Gut microbiota changes before the onset of Alzheimer's disease (AD) and the alterations could be detected in the stage of mild cognitive impairment (MCI). The findings might offer diagnostic biomarkers before the onset of dementia.

BACKGROUND

AD is the most common cause of dementia, and MCI is the predementia state. Recent studies suggest the alterations in the gut microbial communities associated with AD, whereas the microbiota in MCI before the onset of dementia has not been discovered and characterized in humans.

NEW/UPDATED HYPOTHESIS

We hypothesize that the dysbiosis happens in the MCI stage. Patients with AD and MCI have decreased microbial diversity, and changes in gut microbiota could be detected for early detection of AD. In our preliminary study, we identified differences between AD and normal controls in 11 genera from the feces and 11 genera from the blood. No difference in genera between AD and MCI was detected. Using the diagnostic model from fecal samples with all different genera input, 93% (28 in 30) of patients with MCI could be identified correctly.

MAJOR CHALLENGES FOR THE HYPOTHESIS

The diagnosis of MCI and AD in the study was based on symptoms and neuroimaging, and AD biomarkers should be included for precise diagnosis in further validating studies. Besides, as the microbiota changes longitudinally, their relationship with the progress of dementia needs to be studied in the prospective studies.

LINKAGE TO OTHER MAJOR THEORIES

Escherichia was observed increased at genus level in both fecal and blood samples from AD and MCI. For AD biomarker, postmortem brain tissue from patients with AD showed lipopolysaccharides and gram-negative Escherichia coli fragments colocalize with amyloid plaque. In this way, the amyloid pathogenesis for AD would be triggered during MCI by gut microbiota shifting. Besides, systemic inflammatory reactions caused by compounds secreted by bacteria may impair the blood-brain barrier and promote neuroinflammation and/or neurodegeneration. Furthermore, abnormal metabolites caused by microbial gene functions have an impact on neurodegeneration.

Gut Microbiota as a Therapeutic Target to Ameliorate the Biochemical, Neuroanatomical, and Behavioral Effects of Traumatic Brain Injuries

Current efficacious treatments for traumatic brain injury (TBI) are lacking. Establishment of a protective gut microbiota population offers a compelling therapeutic avenue, as brain injury induces disruptions in the composition of the gut microbiota, i.e., gut dysbiosis, which has been shown to contribute to TBI-related neuropathology and impaired behavioral outcomes. The gut microbiome is involved in the modulation of a multitude of cellular and molecular processes fundamental to the progression of TBI-induced pathologies including neuroinflammation, blood brain barrier permeability, immune system response, microglial activation, and mitochondrial dysfunction, as well as intestinal motility and permeability. Additionally, gut dysbiosis further aggravates behavioral impairments in animal models of TBI and spinal cord injury, as well as negatively affects health outcomes in murine stroke models. Recent studies indicate that microbiota transplants and probiotics ameliorate neuroanatomical damage and functional impairments in animal models of stroke and spinal cord injury. In addition, probiotics have been shown to reduce the rate of infection and time spent in intensive care of hospitalized patients suffering from brain trauma. Perturbations in the composition of the gut microbiota and its metabolite profile may also serve as potential diagnostic and theragnostic biomarkers for injury severity and progression. This review aims to address the etiological role of the gut microbiome in the biochemical, neuroanatomical, and behavioral/cognitive consequences of TBI, as well as explore the potential of gut microbiome manipulation in the form of probiotics as an effective therapeutic to ameliorate TBI-induced pathology and symptoms.

Correlation between Jejunal Microbial Diversity and Muscle Fatty Acids Deposition in Broilers Reared at Different Ambient Temperatures

Temperature, which is an important environmental factor in broiler farming, can significantly influence the deposition of fatty acids in muscle. 300 one-day-old broiler chicks were randomly divided into three groups and reared at high, medium and low temperatures (HJ, MJ and LJ), respectively. Breast muscle and jejunal chyme samples were collected and subjected to analyses of fatty acid composition and 16S rRNA gene sequencing. Through spearman’s rank correlation coefficient, the data were used to characterize the correlation between jejunal microbial diversity and muscle fatty acid deposition in the broilers. The results showed that Achromobacter, Stenotrophomonas, Pandoraea, Brevundimonas, Petrobacter and Variovorax were significantly enriched in the MJ group, and all of them were positively correlated with the fatty acid profiling of muscle and multiple lipid metabolism signaling pathways. Lactobacillus was significantly enriched in the HJ group and exhibited a positive correlation with fatty acid deposition. Pyramidobacter, Dialister, Bacteroides and Selenomonas were significantly enriched in the LJ group and displayed negative correlation with fatty acid deposition. Taken together, this study demonstrated that the jejunal microflora manifested considerable changes at high and low ambient temperatures and that jejunal microbiota changes were correlated with fatty acid deposition of muscle in broilers.

Hypoxia and Inflammation as a Consequence of β-Fibril Accumulation: A Perspective View for New Potential Therapeutic Targets

Amyloidoses are heterogeneous diseases that result from the deposition of toxic insoluble β-sheet fibrillar protein aggregates in different tissues. The cascade of molecular events leading to amyloidoses and to the related clinical manifestations is not completely understood. Nevertheless, it is known that tissue damage associated to this disease involves alteration of tissue architecture, interaction with cell surface receptors, inflammation elicited by the amyloid protein deposition, oxidative stress, and apoptosis. However, another important aspect to consider is that systemic protein massive deposition not only subverts tissue architecture but also determines a progressive cellular hypertrophy and dilation of the extracellular space enlarging the volume of the organ. Such an alteration increases the distance between cells and vessels with a drop in pO₂ that, in turn, causes both necrotic cell death and activation of the hypoxia transcription factor HIF-1α. Herewith, we propose the hypothesis that both cell death and hypoxia represent two important events for the pathogenesis of damage and progression of amyloidoses. In fact, molecules released by necrotic cells activate inflammatory cells from one side while binding to HIF-1α-dependent membrane receptors expressed on hypoxic parenchymal cells on the other side. This latter event generates a signaling cascade triggering NFκB activation and chronic inflammation. Finally, we also suggest that this scenario, once proved and detailed, might suggest important targets for new therapeutic interventions.

Microbiota-gut brain axis involvement in neuropsychiatric disorders

Introduction: The microbiota-gut brain (MGB) axis is the bidirectional communication between the intestinal microbiota and the brain. An increasing body of preclinical and clinical evidence has revealed that the gut microbial ecosystem can affect neuropsychiatric health. However, there is still a need of further studies to elucidate the complex gene-environment interactions and the role of the MGB axis in neuropsychiatric diseases, with the aim of identifying biomarkers and new therapeutic targets, to allow early diagnosis and improving treatments. Areas covered: To review the role of MGB axis in neuropsychiatric disorders, prediction and prevention of disease through exploitation, integration, and combination of data from existing gut microbiome/microbiota projects and appropriate other International '-Omics' studies. The authors also evaluated the new technological advances to investigate and modulate, through nutritional and other interventions, the gut microbiota. Expert opinion: The clinical studies have documented an association between alterations in gut microbiota composition and/or function, whereas the preclinical studies support a role for the gut microbiota in impacting behaviors which are of relevance to psychiatry and other central nervous system (CNS) disorders. Targeting MGB axis could be an additional approach for treating CNS disorders and all conditions in which alterations of the gut microbiota are involved.

Association between the oral microbiome and brain resting state connectivity in smokers

Recent studies have shown a critical role of the gastrointestinal microbiome in brain and behavior via the complex gut-microbiome-brain axis. However, the influence of the oral microbiome in neurological processes is much less studied, especially in response to the stimuli, such as smoking, within the oral microenvironment. Additionally, given the complex structural and functional networks in brain, our knowledge about the relationship between microbiome and brain function through specific brain circuits is still very limited. In this pilot study, we leveraged next generation sequencing for microbiome and functional neuroimaging technique to enable the delineation of microbiome-brain network links as well as their relationship to cigarette smoking. Thirty smokers and 30 age- and sex-matched nonsmokers were recruited for 16S sequencing of their oral microbial community. Among them, 56 subjects were scanned by resting-state functional magnetic resonance imaging to derive brain functional networks. Statistical analyses were performed to demonstrate the influence of smoking on the oral microbial composition, functional network connectivity, and the associations between microbial shifts and functional network connectivity alternations. Compared to nonsmokers, we found a significant decrease of beta diversity (P = 6 × 10^-3) in smokers and identified several classes (Betaproteobacteria, Spirochaetia, Synergistia, and Mollicutes) with significant alterations in microbial abundance. Pathway analysis on the predicted KEGG pathways shows that the microbiota with altered abundance are mainly involved in pathways related to cell processes, DNA repair, immune system, and neurotransmitters signaling. One brain functional network connectivity component was identified to have a significant difference between smokers and nonsmokers (P = 0.032), mainly including connectivity between brain default network and other task-positive networks. This brain functional component was also significantly associated with smoking related microbiota, suggesting a correlated cross-individual pattern between smoking-induced oral microbiome dysbiosis and brain functional connectivity alternation, possibly involving immunological and neurotransmitter signaling pathways. This work is the first attempt to link oral microbiome and brain functional networks, and provides support for future work in characterizing the role of oral microbiome in mediating smoking effects on brain activity.

Antibiotics, gut microbiota, and Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease whose various pathophysiological aspects are still being investigated. Recently, it has been hypothesized that AD may be associated with a dysbiosis of microbes in the intestine. In fact, the intestinal flora is able to influence the activity of the brain and cause its dysfunctions.Given the growing interest in this topic, the purpose of this review is to analyze the role of antibiotics in relation to the gut microbiota and AD. In the first part of the review, we briefly review the role of gut microbiota in the brain and the various theories supporting the hypothesis that dysbiosis can be associated with AD pathophysiology. In the second part, we analyze the possible role of antibiotics in these events. Antibiotics are normally used to remove or prevent bacterial colonization in the human body, without targeting specific types of bacteria. As a result, broad-spectrum antibiotics can greatly affect the composition of the gut microbiota, reduce its biodiversity, and delay colonization for a long period after administration. Thus, the action of antibiotics in AD could be wide and even opposite, depending on the type of antibiotic and on the specific role of the microbiome in AD pathogenesis.Alteration of the gut microbiota can induce changes in brain activity, which raise the possibility of therapeutic manipulation of the microbiome in AD and other neurological disorders. This field of research is currently undergoing great development, but therapeutic applications are still far away. Whether a therapeutic manipulation of gut microbiota in AD could be achieved using antibiotics is still not known. The future of antibiotics in AD depends on the research progresses in the role of gut bacteria. We must first understand how and when gut bacteria act to promote AD. Once the role of gut microbiota in AD is well established, one can think to induce modifications of the gut microbiota with the use of pre-, pro-, or antibiotics to produce therapeutic effects.