Microbiota controls the homeostasis of glial cells in the gut lamina propria

Cross-talk between adipose tissue and microbiota-gut-brain-axis in brain development and neurological disorder

The gut microbiota is an important factor responsible for the physiological processes as well as pathogenesis of host. The communication between central nervous system (CNS) and microbiota occurs by different pathways i.e., chemical, neural, immune, and endocrine. Alteration in gut microbiota i.e., gut dysbiosis causes alteration in the bidirectional communication between CNS and gut microbiota and linked to the pathogenesis of neurological and neurodevelopmental disorder. Therefore, now-a-days microbiota-gut-brain-axis (MGBA) has emerged as therapeutic target for the treatment of metabolic disorder. But, experimental data available on MGBA from basic research has limited application in clinical study. In present study we first summarized molecular mechanism of microbiota interaction with brain physiology and pathogenesis via collecting data from different sources i.e., PubMed, Scopus, Web of Science. Furthermore, evidence shows that adipose tissue (AT) is active during metabolic activities and may also interact with MGBA. Hence, in present study we have focused on the relationship among MGBA, brown adipose tissue, and white adipose tissue. Along with this, we have also studied functional specificity of AT, and understanding heterogeneity among MGBA and different types of AT. Therefore, molecular interaction among them may provide therapeutic target for the treatment of neurological disorder.

The role of the gut microbiome in neuroinflammation and chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most debilitating adverse effects caused by chemotherapy drugs such as paclitaxel, oxaliplatin and vincristine. It is untreatable and often leads to the discontinuation of cancer therapy and a decrease in the quality of life of cancer patients. It is well-established that neuroinflammation and the activation of immune and glial cells are among the major drivers of CIPN. However, these processes are still poorly understood, and while many chemotherapy drugs alone can drive the activation of these cells and consequent neuroinflammation, it remains elusive to what extent the gut microbiome influences these processes. In this review, we focus on the peripheral mechanisms driving CIPN, and we address the bidirectional pathways by which the gut microbiome communicates with the immune and nervous systems. Additionally, we critically evaluate literature addressing how chemotherapy-induced dysbiosis and the consequent imbalance in bacterial products may contribute to the activation of immune and glial cells, both of which drive neuroinflammation and possibly CIPN development, and how we could use this knowledge for the development of effective treatment strategies.

Schwann cells and enteric glial cells: Emerging stars in colorectal cancer

Cancer neuroscience, a promising field dedicated to exploring interactions between cancer and the nervous system, has attracted growing attention. The gastrointestinal tracts exhibit extensive innervation, notably characterized by intrinsic innervation. The gut harbors a substantial population of glial cells, including Schwann cells wrapping axons of neurons in the peripheral nervous system and enteric glial cells intricately associated with intrinsic innervation. Glial cells play a crucial role in maintaining the physiological functions of the intestine, encompassing nutrient absorption, barrier integrity, and immune modulation. Nevertheless, it has only been in recent times that the significance of glial cells within colorectal cancer (CRC) has begun to receive considerable attention. Emerging data suggests that glial cells in the gut contribute to the progression and metastasis of CRC, by interacting with cancer cells, influencing inflammation, and modulating the tumor microenvironment. Here, we summarize the significant roles of glial cells in the development and progression of CRC and discuss the latest technologies that can be integrated into this field for in-depth exploration, as well as potential specific targeted strategies for future exploration to benefit patients.

Psychobiotic Properties of Lactiplantibacillus plantarum in Neurodegenerative Diseases

Neurodegenerative disorders are the main cause of cognitive and physical disabilities, affect millions of people worldwide, and their incidence is on the rise. Emerging evidence pinpoints a disturbance of the communication of the gut-brain axis, and in particular to gut microbial dysbiosis, as one of the contributors to the pathogenesis of these diseases. In fact, dysbiosis has been associated with neuro-inflammatory processes, hyperactivation of the neuronal immune system, impaired cognitive functions, aging, depression, sleeping disorders, and anxiety. With the rapid advance in metagenomics, metabolomics, and big data analysis, together with a multidisciplinary approach, a new horizon has just emerged in the fields of translational neurodegenerative disease. In fact, recent studies focusing on taxonomic profiling and leaky gut in the pathogenesis of neurodegenerative disorders are not only shedding light on an overlooked field but are also creating opportunities for biomarker discovery and development of new therapeutic and adjuvant strategies to treat these disorders. Lactiplantibacillus plantarum (LBP) strains are emerging as promising psychobiotics for the treatment of these diseases. In fact, LBP strains are able to promote eubiosis, increase the enrichment of bacteria producing beneficial metabolites such as short-chain fatty acids, boost the production of neurotransmitters, and support the homeostasis of the gut-brain axis. In this review, we summarize the current knowledge on the role of the gut microbiota in the pathogenesis of neurodegenerative disorders with a particular focus on the benefits of LBP strains in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, autism, anxiety, and depression.

Impacts of microbiota and its metabolites through gut-brain axis on pathophysiology of major depressive disorder

Major depressive disorder (MDD) is characterized by a high rate of recurrence and disability, which seriously affects the quality of life of patients. That's why a deeper understanding of the mechanisms of MDD pathology is an urgent task, and some studies have found that intestinal symptoms accompany people with MDD. The microbiota-gut-brain axis is the bidirectional communication between the gut microbiota and the central nervous system, which was found to have a strong association with the pathogenesis of MDD. Previous studies have focused more on the communication between the gut and the brain through neuroendocrine, neuroimmune and autonomic pathways, and the role of gut microbes and their metabolites in depression is unclear. Metabolites of intestinal microorganisms (e.g., tryptophan, kynurenic acid, indole, and lipopolysaccharide) can participate in the pathogenesis of MDD through immune and inflammatory pathways or by altering the permeability of the gut and blood-brain barrier. In addition, intestinal microbes can communicate with intestinal neurons and glial cells to affect the integrity and function of intestinal nerves. However, the specific role of gut microbes and their metabolites in the pathogenesis of MDD is not well understood. Hence, the present review summarizes how gut microbes and their metabolites are directly or indirectly involved in the pathogenesis of MDD.

HIV-associated neurocognitive disorder: key implications of the microbiota-gut-brain axis

HIV-associated neurocognitive disorder (HAND) is now recognized to be relatively common in people living with HIV (PLWH), and remains a common cause of cognitive impairment. Unfortunately, the fundamental pathogenic processes underlying this specific outcome of HIV infection have not as yet been fully elucidated. With increased interest in research related to the microbiota-gut-brain axis, the gut-brain axis has been shown to play critical roles in regulating central nervous system disorders such as Alzheimer's disease and Parkinson's disease. PLWH are characterized by a particular affliction, referred to as gut-associated dysbiosis syndrome, which provokes an alteration in microbial composition and diversity, and of their associated metabolite composition within the gut. Interestingly, the gut microbiota has also been recognized as a key element, which both positively and negatively influences human brain health, including the functioning and development of the central nervous system (CNS). In this review, based on published evidence, we critically discuss the relevant interactions between the microbiota-gut-brain axis and the pathogenesis of HAND in the context of HIV infection. It is likely that HAND manifestation in PLWH mainly results from (i) gut-associated dysbiosis syndrome and a leaky gut on the one hand and (ii) inflammation on the other hand. In other words, the preceding features of HIV infection negatively alter the composition of the gut microbiota (microbes and their associated metabolites) and promote proinflammatory immune responses which singularly or in tandem damage neurons and/or induce inadequate neuronal signaling. Thus, HAND is fairly prevalent in PLWH. This work aims to demonstrate that in the quest to prevent and possibly treat HAND, the gut microbiota may ultimately represent a therapeutically targetable "host factor."

Single-cell atlas of the small intestine throughout the human lifespan demonstrates unique features of fetal immune cells

Proper development of mucosal immunity is critical for human health. Over the past decade, it has become evident that in humans, this process begins in utero. However, there are limited data on the unique features and functions of fetal mucosal immune cells. To address this gap, we integrated several single-cell ribonucleic acid sequencing datasets of the human small intestine (SI) to create an SI transcriptional atlas throughout the human life span, ranging from the first trimester to adulthood, with a focus on immune cells. Fetal SI displayed a complex immune landscape comprising innate and adaptive immune cells that exhibited distinct transcriptional programs from postnatal samples, especially compared with pediatric and adult samples. We identified shifts in myeloid populations across gestation and progression of memory T-cell states throughout the human lifespan. In particular, there was a marked shift of memory T cells from those with stem-like properties in the fetal samples to fully differentiated cells with a high expression of activation and effector function genes in adult samples, with neonatal samples containing both features. Finally, we demonstrate that the SI developmental atlas can be used to elucidate improper trajectories linked to mucosal diseases by implicating developmental abnormalities underlying necrotizing enterocolitis, a severe intestinal complication of prematurity. Collectively, our data provide valuable resources and important insights into intestinal immunity that will facilitate regenerative medicine and disease understanding.

Cellular Components of the Blood-Brain Barrier and Their Involvement in Aging-Associated Cognitive Impairment

Human life expectancy has been significantly extended, which poses major challenges to our healthcare and social systems. Aging-associated cognitive impairment is attributed to endothelial dysfunction in the cardiovascular system and neurological dysfunction in the central nervous system. The central nervous system is considered an immune-privileged tissue due to the exquisite protection provided by the blood-brain barrier. The present review provides an overview of the structure and function of blood-brain barrier, extending the cell components of blood-brain barrier from endothelial cells and pericytes to astrocytes, perivascular macrophages and oligodendrocyte progenitor cells. In particular, the pathological changes in the blood-brain barrier in aging, with special focus on the underlying mechanisms and molecular changes, are presented. Furthermore, the potential preventive/therapeutic strategies against aging-associated blood-brain barrier disruption are discussed.

Dihydroartemisinin Modulates Enteric Glial Cell Heterogeneity to Alleviate Colitis

The precise mechanism underlying the therapeutic effects of dihydroartemisinin (DHA) in alleviating colitis remains incompletely understood. A strong correlation existed between the elevation of glial fibrillary acidic protein (GFAP)+/S100 calcium binding protein B (S100β)+ enteric glial cells (EGCs) in inflamed colonic tissues and the disruption of the intestinal epithelial barrier (IEB) and gut vascular barrier (GVB) observed in chronic colitis. DHA demonstrated efficacy in restoring the functionality of the dual gut barrier while concurrently attenuating intestinal inflammation. Mechanistically, DHA inhibited the transformation of GFAP+ EGCs into GFAP+/S100β+ EGCs while promoting the differentiation of GFAP+/S100β+ EGCs back into GFAP+ EGCs. Furthermore, DHA induced apoptosis in GFAP+/S100β+ EGCs by inducing cell cycle arrest at the G0/G1 phase. The initial mechanism is further validated that DHA regulates EGC heterogeneity by improving dysbiosis in colitis. These findings underscore the multifaceted therapeutic potential of DHA in ameliorating colitis by improving dysbiosis, modulating EGC heterogeneity, and preserving gut barrier integrity, thus offering promising avenues for novel therapeutic strategies for inflammatory bowel diseases.

Distribution and ultrastructural characteristics of enteric glial cell in the chicken cecum

Enteric glial cell (EGC) is involved in neuroimmune regulation within the enteric nervous system (ENS); however, limited information exists on the distribution and ultrastructure of EGC in the poultry gut. We aim to investigate the morphological features and distribution of EGC in the chicken cecum. Here, we investigated the distribution and ultrastructural features of chicken cecum EGC using immunohistochemistry (IHC) and transmission electron microscopy (TEM). IHC showed that EGC was widely distributed throughout the chicken cecum. In the mucosal layer, EGC was morphologically irregular, with occasionally interconnecting protrusions that outlined signal-negative neurons. The morphology of EGC in the submucosal layer was also irregular. In the inner circular muscle layer and between the inner circular and outer longitudinal muscle layers, EGC aligned parallel to the circular muscle cells. A small number of EGC with an irregular morphology were found in the outer longitudinal muscle layer. In addition, in the submucosal and myenteric plexus, EGC were aggregated, and the protrusions of the immunoreactive cells interconnected to outline the bodies of nonreactive neurons. TEM-guided ultrastructural characterization confirmed the IHC findings that EGC were morphologically irregular and revealed they developed either a star, bipolar, or fibrous shape. The nucleus was also irregular, with electron-dense heterochromatin distributed in the center of the nucleus or on the nuclear membrane. The cytoplasm contained many glial filaments and vesicle-containing protrusions from neuronal cells; organelles were rare. EGC was in close contact with other cells in their vicinity. These findings suggest that EGC is well-situated to exert influence on intestinal motility and immune functions through mechanical contraction and chemical secretion.

From diversity to disease: unravelling the role of enteric glial cells

Enteric glial cells (EGCs) are an essential component of the enteric nervous system (ENS) and play key roles in gastrointestinal development, homeostasis, and disease. Derived from neural crest cells, EGCs undergo complex differentiation processes regulated by various signalling pathways. Being among the most dynamic cells of the digestive system, EGCs react to cues in their surrounding microenvironment and communicate with various cell types and systems within the gut. Morphological studies and recent single cell RNA sequencing studies have unveiled heterogeneity among EGC populations with implications for regional functions and roles in diseases. In gastrointestinal disorders, including inflammatory bowel disease (IBD), infections and cancer, EGCs modulate neuroplasticity, immune responses and tumorigenesis. Recent evidence suggests that EGCs respond plastically to the microenvironmental cues, adapting their phenotype and functions in disease states and taking on a crucial role. They exhibit molecular abnormalities and alter communication with other intestinal cell types, underscoring their therapeutic potential as targets. This review delves into the multifaceted roles of EGCs, particularly emphasizing their interactions with various cell types in the gut and their significant contributions to gastrointestinal disorders. Understanding the complex roles of EGCs in gastrointestinal physiology and pathology will be crucial for the development of novel therapeutic strategies for gastrointestinal disorders.

Lactobacillus-derived protoporphyrin IX and SCFAs regulate the fiber size via glucose metabolism in the skeletal muscle of chickens

The gut microbiota contributes to skeletal muscle energy metabolism and is an indirect factor affecting meat quality. However, the role of specific gut microbes in energy metabolism and fiber size of skeletal muscle in chickens remains largely unknown. In this study, we first performed cecal microbiota transplantation from Chinese indigenous Jingyuan chickens (JY) to Arbor Acres chickens (AA), to determine the effects of microbiota on skeletal muscle fiber and energy metabolism. Then, we used metagenomics, gas chromatography, and metabolomics analysis to identify functional microbes. Finally, we validated the role of these functional microbes in regulating the fiber size via glucose metabolism in the skeletal muscle of chickens through feeding experiments. The results showed that the skeletal muscle characteristics of AA after microbiota transplantation tended to be consistent with that of JY, as the fiber diameter was significantly increased, and glucose metabolism level was significantly enhanced in the pectoralis muscle. L. plantarum, L. ingluviei, L. salivarius, and their mixture could increase the production of the microbial metabolites protoporphyrin IX and short-chain fatty acids, therefore increasing the expression levels of genes related to the oxidative fiber type (MyHC SM and MyHC FRM), mitochondrial function (Tfam and CoxVa), and glucose metabolism (PFK, PK, PDH, IDH, and SDH), thereby increasing the fiber diameter and density. These three Lactobacillus species could be promising probiotics to improve the meat quality of chicken.IMPORTANCEThis study revealed that the L. plantarum, L. ingluviei, and L. salivarius could enhance the production of protoporphyrin IX and short-chain fatty acids in the cecum of chickens, improving glucose metabolism, and finally cause the increase in fiber diameter and density of skeletal muscle. These three microbes could be potential probiotic candidates to regulate glucose metabolism in skeletal muscle to improve the meat quality of chicken in broiler production.

An overview on the cellular mechanisms of anthocyanins in maintaining intestinal integrity and function

Structural and functional changes of the intestinal barrier, as a consequence of a number of (epi)genetic and environmental causes, have a main role in penetrations of pathogens and toxic agents, and lead to the development of inflammation-related pathological conditions, not only at the level of the GI tract but also in other extra-digestive tissues and organs. Anthocyanins (ACNs), a subclass of polyphenols belonging to the flavonoid group, are well known for their health-promoting properties and are widely distributed in the human diet. There is large evidence about the correlation between the human intake of ACN-rich products and a reduction of intestinal inflammation and dysfunction. Our review describes the more recent advances in the knowledge of cellular and molecular mechanisms through which ACNs can modulate the main mechanisms involved in intestinal dysfunction and inflammation, in particular the inhibition of the NF-κB, JNK, MAPK, STAT3, and TLR4 proinflammatory pathways, the upregulation of the Nrf2 transcription factor and the expression of tight junction proteins and mucins.

Global research status and trends of enteric glia: a bibliometric analysis

Background

Enteric glia are essential components of the enteric nervous system. Previously believed to have a passive structural function, mounting evidence now suggests that these cells are indispensable for maintaining gastrointestinal homeostasis and exert pivotal influences on both wellbeing and pathological conditions. This study aimed to investigate the global status, research hotspots, and future directions of enteric glia.

Methods

The literature on enteric glia research was acquired from the Web of Science Core Collection. VOSviewer software (v1.6.19) was employed to visually represent co-operation networks among countries, institutions, and authors. The co-occurrence analysis of keywords and co-citation analysis of references were conducted using CiteSpace (v6.1.R6). Simultaneously, cluster analysis and burst detection of keywords and references were performed.

Results

A total of 514 publications from 36 countries were reviewed. The United States was identified as the most influential country. The top-ranked institutions were University of Nantes and Michigan State University. Michel Neunlist was the most cited author. "Purinergic signaling" was the largest co-cited reference cluster, while "enteric glial cells (EGCs)" was the cluster with the highest number of co-occurring keywords. As the keyword with the highest burst strength, Crohns disease was a hot topic in the early research on enteric glia. The burst detection of keywords revealed that inflammation, intestinal motility, and gut microbiota may be the research frontiers.

Conclusion

This study provides a comprehensive bibliometric analysis of enteric glia research. EGCs have emerged as a crucial link between neurons and immune cells, attracting significant research attention in neurogastroenterology. Their fundamental and translational studies on inflammation, intestinal motility, and gut microbiota may promote the treatment of some gastrointestinal and parenteral disorders.

Neuroimmune Connectomes in the Gut and Their Implications in Parkinson's Disease

The gastrointestinal tract is the largest immune organ and it receives dense innervation from intrinsic (enteric) and extrinsic (sympathetic, parasympathetic, and somatosensory) neurons. The immune and neural systems of the gut communicate with each other and their interactions shape gut defensive mechanisms and neural-controlled gut functions such as motility and secretion. Changes in neuroimmune interactions play central roles in the pathogenesis of diseases such as Parkinson's disease (PD), which is a multicentric disorder that is heterogeneous in its manifestation and pathogenesis. Non-motor and premotor symptoms of PD are common in the gastrointestinal tract and the gut is considered a potential initiation site for PD in some cases. How the enteric nervous system and neuroimmune signaling contribute to PD disease progression is an emerging area of interest. This review focuses on intestinal neuroimmune loops such as the neuroepithelial unit, enteric glial cells and their immunomodulatory effects, anti-inflammatory cholinergic signaling and the relationship between myenteric neurons and muscularis macrophages, and the role of α-synuclein in gut immunity. Special consideration is given to the discussion of intestinal neuroimmune connectomes during PD and their possible implications for various aspects of the disease.

Gastrointestinal and brain barriers: unlocking gates of communication across the microbiota-gut-brain axis

Crosstalk between gut and brain has long been appreciated in health and disease, and the gut microbiota is a key player in communication between these two distant organs. Yet, the mechanisms through which the microbiota influences development and function of the gut-brain axis remain largely unknown. Barriers present in the gut and brain are specialized cellular interfaces that maintain strict homeostasis of different compartments across this axis. These barriers include the gut epithelial barrier, the blood-brain barrier and the blood-cerebrospinal fluid barrier. Barriers are ideally positioned to receive and communicate gut microbial signals constituting a gateway for gut-microbiota-brain communication. In this Review, we focus on how modulation of these barriers by the gut microbiota can constitute an important channel of communication across the gut-brain axis. Moreover, barrier malfunction upon alterations in gut microbial composition could form the basis of various conditions, including often comorbid neurological and gastrointestinal disorders. Thus, we should focus on unravelling the molecular and cellular basis of this communication and move from simplistic framing as 'leaky gut'. A mechanistic understanding of gut microbiota modulation of barriers, especially during critical windows of development, could be key to understanding the aetiology of gastrointestinal and neurological disorders.

Effects of different temperatures on Leiocassis longirostris gill structure and intestinal microbial composition

Fish are poikilothermic vertebrates and their physiological activities are affected by water temperature. In recent years, extreme weather has occurred frequently, and temperature changes have adversely affected the growth of farmed fish. To explore the changes in gill tissue structure caused by changing the water temperature and the relationship between the intestinal microbiota and the Leiocassis longirostris host adaptation mechanism, gill tissue sections and intestinal microbial 16S rRNA amplicon sequencing were conducted under different temperature stress (low temperature 4 °C, normal temperature 26 °C and high temperature 32 °C). The results showed that heat stress and cold stress caused injury and swelling, terminal congestion, cell vacuolation, and necrosis of the gill tissue of L. longirostris. For intestinal microbiota, the abundances of Pseudomonadota and Bacillota increased at the cold stress, while the abundances of Fusobacteriota and Bacteroidota increased at the heat stress. The number of opportunistic bacteria, mainly Aeromonas and Acinetobacter, was the highest under cold stress. In addition, the richness of the intestinal microbiota decreased significantly at heat and cold stresses, while evenness increased. Prediction of intestinal microbiota function showed that most common functions, such as metabolism of cofactors and vitamins, energy metabolism and replication and repair, were decreased significantly at heat stress and cold stress, and phylogenetic relationship analysis revealed significant differences among the groups. In conclusion, the change of temperature altered the gill tissue structure, and affected the structure and homeostasis of the intestinal microbiota, thus affecting the survival time of L. longirostris, and cold stress had a greater effect than heat stress.

Key roles of glial cells in the encephalopathy of prematurity

Across the globe, approximately one in 10 babies are born preterm, that is, before 37 weeks of a typical 40 weeks of gestation. Up to 50% of preterm born infants develop brain injury, encephalopathy of prematurity (EoP), that substantially increases their risk for developing lifelong defects in motor skills and domains of learning, memory, emotional regulation, and cognition. We are still severely limited in our abilities to prevent or predict preterm birth. No longer just the "support cells," we now clearly understand that during development glia are key for building a healthy brain. Glial dysfunction is a hallmark of EoP, notably, microgliosis, astrogliosis, and oligodendrocyte injury. Our knowledge of glial biology during development is exponentially expanding but hasn't developed sufficiently for development of effective neuroregenerative therapies. This review summarizes the current state of knowledge for the roles of glia in infants with EoP and its animal models, and a description of known glial-cell interactions in the context of EoP, such as the roles for border-associated macrophages. The field of perinatal medicine is relatively small but has worked passionately to improve our understanding of the etiology of EoP coupled with detailed mechanistic studies of pre-clinical and human cohorts. A primary finding from this review is that expanding our collaborations with computational biologists, working together to understand the complexity of glial subtypes, glial maturation, and the impacts of EoP in the short and long term will be key to the design of therapies that improve outcomes.

Enteric glial cell network function is required for epithelial barrier restitution following intestinal ischemic injury in the early postnatal period

Ischemic damage to the intestinal epithelial barrier, such as in necrotizing enterocolitis or small intestinal volvulus, is associated with higher mortality rates in younger patients. We have recently reported a powerful pig model to investigate these age-dependent outcomes in which mucosal barrier restitution is strikingly absent in neonates but can be rescued by direct application of homogenized mucosa from older, juvenile pigs by a yet-undefined mechanism. Within the mucosa, a postnatally developing network of enteric glial cells (EGCs) is gaining recognition as a key regulator of the mucosal barrier. Therefore, we hypothesized that the developing EGC network may play an important role in coordinating intestinal barrier repair in neonates. Neonatal and juvenile jejunal mucosa recovering from surgically induced intestinal ischemia was visualized by scanning electron microscopy and the transcriptomic phenotypes were assessed by bulk RNA sequencing. EGC network density and glial activity were examined by Gene Set Enrichment Analysis, three-dimensional (3-D) volume imaging, and Western blot and its function in regulating epithelial restitution was assessed ex vivo in Ussing chamber using the glia-specific inhibitor fluoroacetate (FA), and in vitro by coculture assay. Here we refine and elaborate our translational model, confirming a neonatal phenotype characterized by a complete lack of coordinated reparative signaling in the mucosal microenvironment. Furthermore, we report important evidence that the subepithelial EGC network changes significantly over the early postnatal period and demonstrate that the proximity of a specific functional population of EGC to wounded intestinal epithelium contributes to intestinal barrier restitution following ischemic injury.NEW & NOTEWORTHY This study refines a powerful translational pig model, defining an age-dependent relationship between enteric glia and the intestinal epithelium during intestinal ischemic injury and confirming an important role for enteric glial cell (EGC) activity in driving mucosal barrier restitution. This study suggests that targeting the enteric glial network could lead to novel interventions to improve recovery from intestinal injury in neonatal patients.

Autism spectrum disorders and the gastrointestinal tract: insights into mechanisms and clinical relevance

Autism spectrum disorders (ASDs) are recognized as central neurodevelopmental disorders diagnosed by impairments in social interactions, communication and repetitive behaviours. The recognition of ASD as a central nervous system (CNS)-mediated neurobehavioural disorder has led most of the research in ASD to be focused on the CNS. However, gastrointestinal function is also likely to be affected owing to the neural mechanistic nature of ASD and the nervous system in the gastrointestinal tract (enteric nervous system). Thus, it is unsurprising that gastrointestinal disorders, particularly constipation, diarrhoea and abdominal pain, are highly comorbid in individuals with ASD. Gastrointestinal problems have also been repeatedly associated with increased severity of the core symptoms diagnostic of ASD and other centrally mediated comorbid conditions, including psychiatric issues, irritability, rigid-compulsive behaviours and aggression. Despite the high prevalence of gastrointestinal dysfunction in ASD and its associated behavioural comorbidities, the specific links between these two conditions have not been clearly delineated, and current data linking ASD to gastrointestinal dysfunction have not been extensively reviewed. This Review outlines the established and emerging clinical and preclinical evidence that emphasizes the gut as a novel mechanistic and potential therapeutic target for individuals with ASD.

Enteric glial cells contribute to chronic stress-induced alterations in the intestinal microbiota and barrier in rats

Background

Emerging evidence has demonstrated the impact of psychological stress on intestinal microbiota, however, the precise mechanisms are not fully understood. Enteric glia, a unique type of peripheral glia found within the enteric nervous system (ENS), play an active role in enteric neural circuits and have profound effects on gut functions. In the present study, we tested the hypothesis that enteric glia are involved in the alterations in the intestinal microflora and barrier induced by chronic water-avoidance stress (WAS) in the gut.

Methods and results

Western blotting and immunohistochemical (IHC) staining were used to examine the expression of glial fibrillary acidic protein (GFAP), nitric oxide synthetase (NOS) and choline acety1transferase (ChAT) in colon tissues. 16S rDNA sequencing was performed to analyse the composition of the intestinal microbiota in rats. Changes in the tight junction proteins Occludin, Claudin1 and proliferating cell nuclear antigen (PCNA) in the colon tissues were detected after WAS. The abundance of Firmicutes, Proteobacteria, Lactobacillus and Lachnospiraceae_NK4A136 decreased significantly, whereas the abundance of Actinobacteria, Ruminococcaceae_UCG-005 and Christensenellaceae-R-7 increased significantly in stressed rats. Meanwhile, the expression of Occludin, Claudin1 and PCNA significantly decreased after WAS. Treatment with L-A-aminohexanedioic acid (L-AA), a gliotoxin that blunts astrocytic function, obviously decreased the abundance of Actinobacteria, Ruminococcaceae_UCG-005 and Christensenel-laceae_R-7 in stressed rats and significantly increased the abundance of Proteobacteria, Lactobacillus and Lachnospiraceae_NK4A136. In addition, the protein expression of colon Occludin, Claudin1, and PCNA increased after intraperitoneal injection of L-AA. Furthermore, the expression level of NOS in colon tissues was significantly decreased, whereas that of ChAT was significantly increased following L-AA treatment.

Conclusions

Our results showed that enteric glial cells may contribute to WAS-induced changes in the intestinal microbiota and barrier function by modulating the activity of NOS and cholinergic neurones in the ENS.

Confounder or Confederate? The Interactions Between Drugs and the Gut Microbiome in Psychiatric and Neurological Diseases

The gut microbiome is emerging as an important factor in signaling along the gut-brain axis. The intimate physiological connection between the gut and the brain allows perturbations in the microbiome to be directly transmitted to the central nervous system and thereby contribute to psychiatric and neurological diseases. Common microbiome perturbations result from the ingestion of xenobiotic compounds including pharmaceuticals such as psychotropic drugs. In recent years, a variety of interactions between these drug classes and the gut microbiome have been reported, ranging from direct inhibitory effects on gut bacteria to microbiome-mediated drug degradation or sequestration. Consequently, the microbiome may play a critical role in influencing the intensity, duration, and onset of therapeutic effects, as well as in influencing the side effects that patients may experience. Furthermore, because the composition of the microbiome varies from person to person, the microbiome may contribute to the frequently observed interpersonal differences in the response to these drugs. In this review, we first summarize the known interactions between xenobiotics and the gut microbiome. Then, for psychopharmaceuticals, we address the question of whether these interactions with gut bacteria are irrelevant for the host (i.e., merely confounding factors in metagenomic analyses) or whether they may even have therapeutic or adverse effects.

Interaction between Per- and Polyfluorinated Substances (PFAS) and Acetaminophen in Disease Exacerbation-Focusing on Autism and the Gut-Liver-Brain Axis

This review presents a new perspective on the exacerbation of autism spectrum disorder (ASD) by per- and polyfluoroalkyl substances (PFAS) through the gut-liver-brain axis. We have summarized evidence reported on the involvement of the gut microbiome and liver inflammation that led to the onset and exacerbation of ASD symptoms. As PFAS are toxicants that particularly target liver, this review has comprehensively explored the possible interaction between PFAS and acetaminophen, another liver toxicant, as the chemicals of interest for future toxicology research. Our hypothesis is that, at acute dosages, acetaminophen has the ability to aggravate the impaired conditions of the PFAS-exposed liver, which would further exacerbate neurological symptoms such as lack of social communication and interest, and repetitive behaviors using mechanisms related to the gut-liver-brain axis. This review discusses their potential interactions in terms of the gut-liver-brain axis and signaling pathways that may contribute to neurological diseases.

Novel therapeutic strategy for obesity through the gut microbiota-brain axis: A review article

Background: The interaction between commensal bacteria and the host is essential for health and the gut microbiota-brain axis plays a vital role in this regard. Obesity as a medical problem not only affect the health of the individuals, but also the economic and social aspects of communities. The presence of any dysbiosis in the composition of the gut microbiota disrupts in the gut microbiota-brain axis, which in turn leads to an increase in appetite and then obesity. Because common treatments for obesity have several drawbacks, the use of microbiota-based therapy in addition to treatment and prevention of obesity can have other numerous benefits for the individual. In this review, we intend to investigate the relationship between obesity and the gut microbiota-brain axis as well as novel treatment strategies based on this axis with an emphasis on gut microbiota.

Potential roles of enteric glial cells in Crohn's disease: A critical review

Enteric glial cells in the enteric nervous system are critical for the regulation of gastrointestinal homeostasis. Increasing evidence suggests two-way communication between enteric glial cells and both enteric neurons and immune cells. These interactions may be important in the pathogenesis of Crohn's disease (CD), a chronic relapsing disease characterized by a dysregulated immune response. Structural abnormalities in glial cells have been identified in CD. Furthermore, classical inflammatory pathways associated with CD (e.g., the nuclear factor kappa-B pathway) function in enteric glial cells. However, the specific mechanisms by which enteric glial cells contribute to CD have not been summarized in detail. In this review, we describe the possible roles of enteric glial cells in the pathogenesis of CD, including the roles of glia-immune interactions, neuronal modulation, neural plasticity, and barrier integrity. Additionally, the implications for the development of therapeutic strategies for CD based on enteric glial cell-mediated pathogenic processes are discussed.

Regulation of Pain Perception by Microbiota in Parkinson Disease

Pain perception involves current stimulation in peripheral nociceptive nerves and the subsequent stimulation of postsynaptic excitatory neurons in the spinal cord. Importantly, in chronic pain, the neural activity of both peripheral nociceptors and postsynaptic neurons in the central nervous system is influenced by several inflammatory mediators produced by the immune system. Growing evidence has indicated that the commensal microbiota plays an active role in regulating pain perception by either acting directly on nociceptors or indirectly through the modulation of the inflammatory activity on immune cells. This symbiotic relationship is mediated by soluble bacterial mediators or intrinsic structural components of bacteria that act on eukaryotic cells, including neurons, microglia, astrocytes, macrophages, T cells, enterochromaffin cells, and enteric glial cells. The molecular mechanisms involve bacterial molecules that act directly on neurons, affecting their excitability, or indirectly on non-neuronal cells, inducing changes in the production of proinflammatory or anti-inflammatory mediators. Importantly, Parkinson disease, a neurodegenerative and inflammatory disorder that affects mainly the dopaminergic neurons implicated in the control of voluntary movements, involves not only a motor decline but also nonmotor symptomatology, including chronic pain. Of note, several recent studies have shown that Parkinson disease involves a dysbiosis in the composition of the gut microbiota. In this review, we first summarize, integrate, and classify the molecular mechanisms implicated in the microbiota-mediated regulation of chronic pain. Second, we analyze the changes on the commensal microbiota associated to Parkinson disease and propose how these changes affect the development of chronic pain in this pathology. SIGNIFICANCE STATEMENT: The microbiota regulates chronic pain through the action of bacterial signals into two main locations: the peripheral nociceptors and the postsynaptic excitatory neurons in the spinal cord. The dysbiosis associated to Parkinson disease reveals increased representation of commensals that potentially exacerbate chronic pain and reduced levels of bacteria with beneficial effects on pain. This review encourages further research to better understand the signals involved in bacteria-bacteria and bacteria-host communication to get the clues for the development of probiotics with therapeutic potential.

Dietary ingredient change induces a transient MyD88-dependent mucosal enteric glial cell response and promotes obesity

OBJECTIVE

Consumption of a modern Western-type high-fat low-fiber diet increases the risk of obesity. However, how a host responds to such a diet, especially during the early period of dietary transition from a previous low-fat and fiber-rich diet, remains poorly explored.

METHODS

Wild-type C57BL/6 mice were fed a normal chow diet or a high-fat diet. Enteric glial cell (EGC) activation was detected through quantitative real-time PCR (qRT-PCR), immunoblotting and immunohistology analysis. Fluorocitrate or genetic deletion of glial fibrillary acidic protein (GFAP)-positive glial-intrinsic myeloid differentiation factor 88 (Myd88) was used to inhibit EGC activation, and the effect of a high-fat diet on obesity was further investigated. The role of MYD88-dependent sensing of commensal products in adipocyte was observed to analyze the effect of obesity.

RESULTS

A dietary shift from a normal chow diet to a high-fat diet in mice induced a transient early-phase emergence of a GFAP-positive EGC network in the lamina propria of the ileum, accompanied with an increase in glial-derived neurotrophic factor production. Inhibition of glial cell activity blocked this response. GFAP-positive glial Myd88 knockout mice gained less body weight after high-fat diet (HFD) feeding than littermate controls. In contrast, adipocyte deletion of Myd88 in mice had no effect on weight gain but instead exacerbated glucose intolerance. Furthermore, short-term fluorocitrate intervention during HFD feeding attenuated body weight gain.

CONCLUSIONS

Our findings indicate that EGCs are early responders to intestinal ecosystem changes and the GFAP-positive glial Myd88 signaling participates in regulating obesity.

Functional and Transcriptomic Characterization of Postnatal Maturation of ENS and SIP Syncytium in Mice Colon

The interplay of the enteric nervous system (ENS) and SIP syncytium (smooth muscle cells-interstitial cells of Cajal-PDGFRα+ cells) plays an important role in the regulation of gastrointestinal (GI) motility. This study aimed to investigate the dynamic regulatory mechanisms of the ENS-SIP system on colon motility during postnatal development. Colonic samples of postnatal 1-week-old (PW1), 3-week-old (PW3), and 5-week-old (PW5) mice were characterized by RNA sequencing, qPCR, Western blotting, isometric force recordings (IFR), and colonic motor complex (CMC) force measurements. Our study showed that the transcriptional expression of Pdgfrα, c-Kit, P2ry1, Nos1, and Slc18a3, and the protein expression of nNOS, c-Kit, and ANO1 significantly increased with age from PW1 to PW5. In PW1 and PW3 mice, colonic migrating movement was not fully developed. In PW5 mice, rhythmic CMCs were recorded, similar to the CMC pattern described previously in adult mice. The inhibition of nNOS revealed excitatory and non-propulsive responses which are normally suppressed due to ongoing nitrergic inhibition. During postnatal development, molecular data demonstrated the establishment and expansion of ICC and PDGFRα+ cells, along with nitrergic and cholinergic nerves and purinergic receptors. Our findings are important for understanding the role of the SIP syncytium in generating and establishing CMCs in postnatal, developing murine colons.

Enteric glia as a player of gut-brain interactions during Parkinson's disease

The enteric glia has been shown as a potential component of neuroimmune interactions that signal in the gut-brain axis during Parkinson's disease (PD). Enteric glia are a peripheral glial type found in the enteric nervous system (ENS) that, associated with enteric neurons, command various gastrointestinal (GI) functions. They are a unique cell type, with distinct phenotypes and distribution in the gut layers, which establish relevant neuroimmune modulation and regulate neuronal function. Comprehension of enteric glial roles during prodromal and symptomatic phases of PD should be a priority in neurogastroenterology research, as the reactive enteric glial profile, gastrointestinal dysfunction, and colonic inflammation have been verified during the prodromal phase of PD-a moment that may be interesting for interventions. In this review, we explore the mechanisms that should govern enteric glial signaling through the gut-brain axis to understand pathological events and verify the possible windows and pathways for therapeutic intervention. Enteric glia directly modulate several functional aspects of the intestine, such as motility, visceral sensory signaling, and immune polarization, key GI processes found deregulated in patients with PD. The search for glial biomarkers, the investigation of temporal-spatial events involving glial reactivity/signaling, and the proposal of enteric glia-based therapies are clearly demanded for innovative and intestine-related management of PD.

Understanding the Gut-Brain Axis and Its Therapeutic Implications for Neurodegenerative Disorders

The gut-brain axis (GBA) is a complex bidirectional communication network connecting the gut and brain. It involves neural, immune, and endocrine communication pathways between the gastrointestinal (GI) tract and the central nervous system (CNS). Perturbations of the GBA have been reported in many neurodegenerative disorders (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), among others, suggesting a possible role in disease pathogenesis. The gut microbiota is a pivotal component of the GBA, and alterations in its composition, known as gut dysbiosis, have been associated with GBA dysfunction and neurodegeneration. The gut microbiota might influence the homeostasis of the CNS by modulating the immune system and, more directly, regulating the production of molecules and metabolites that influence the nervous and endocrine systems, making it a potential therapeutic target. Preclinical trials manipulating microbial composition through dietary intervention, probiotic and prebiotic supplementation, and fecal microbial transplantation (FMT) have provided promising outcomes. However, its clear mechanism is not well understood, and the results are not always consistent. Here, we provide an overview of the major components and communication pathways of the GBA, as well as therapeutic approaches targeting the GBA to ameliorate NDDs.

Histological study on the reginal difference in the localization of mucosal enteric glial cells and their sheath structure in the rat intestine

The present study aimed to histologically clarify the regional specificity of the mucosal enteric glial cells (mEGCs) in the rat intestine with serial block-face scanning electron microscopy (SBF-SEM). SBF-SEM analysis with the ileum, the cecum and the descending colon revealed that mEGC nuclei were more abundant in the data stacks from the apical portion of the villus and the lateral portion of the crypt of the ileum. mEGCs exhibited a high rate of coverage over the nerve bundle around the lateral portion of the ileal crypt, but showed an extremely low level of coverage in the luminal portion of the cecum. These findings evidenced regional differences in the localization of mEGCs and in their sheath structure in the rat intestine.

Mini-review: Enteric glial cell heterogeneity: Is it all about the niche?

Enteric glial cells represent the enteric population of peripheral glia. According to their 'glial' nature, their principal function is to support enteric neurons in both structural and functional ways. Mounting evidence however demonstrates that enteric glial cells crucially contribute to the majority of enteric nervous system functions, thus acting as pivotal players in the maintenance of gut homeostasis. Various types of enteric glia are present within the gut wall, creating an intricate interaction network with other gastrointestinal cell types. Their distribution throughout the different layers of the gut wall translates in characteristic phenotypes that are tailored to the local tissue requirements of the digestive tract. This heterogeneity is assumed to be mirrored by functional specialization, but the extensive plasticity and versatility of enteric glial cells complicates a one on one phenotype/function definition. Moreover, the relative contribution of niche-specific signals versus lineage determinants for driving enteric glial heterogeneity is still uncertain. In this review we focus on the current understanding of phenotypic and functional enteric glial cell heterogeneity, from a microenvironmental and developmental perspective.

Boundaries and integration between microbiota, the nervous system, and immunity

The enteric nervous system is largely autonomous, and the central nervous system is compartmentalized behind the blood-brain barrier. Yet the intestinal microbiota shapes gut function, local and systemic immune responses, and central nervous system functions including cognition and mood. In this review, we address how the gut microbiota can profoundly influence neural and immune networks. Although many of the interactions between these three systems originate in the intestinal mucosa, intestinal function and immunity are modulated by neural pathways that connect the gut and brain. Furthermore, a subset of microbe-derived penetrant molecules enters the brain and regulates central nervous system function. Understanding how these seemingly isolated entities communicate has the potential to open up new avenues for therapies and interventions.

Harnessing the Power of Enteric Glial Cells' Plasticity and Multipotency for Advancing Regenerative Medicine

The enteric nervous system (ENS), known as the intrinsic nervous system of the gastrointestinal tract, is composed of a diverse array of neuronal and glial cell subtypes. Fascinating questions surrounding the generation of cellular diversity in the ENS have captivated ENS biologists for a considerable time, particularly with recent advancements in cell type-specific transcriptomics at both population and single-cell levels. However, the current focus of research in this field is predominantly restricted to the study of enteric neuron subtypes, while the investigation of enteric glia subtypes significantly lags behind. Despite this, enteric glial cells (EGCs) are increasingly recognized as equally important regulators of numerous bowel functions. Moreover, a subset of postnatal EGCs exhibits remarkable plasticity and multipotency, distinguishing them as critical entities in the context of advancing regenerative medicine. In this review, we aim to provide an updated overview of the current knowledge on this subject, while also identifying key questions that necessitate future exploration.

The gut microbiota-brain axis in neurological disorder

The gut microbiota (GM) plays an important role in the physiology and pathology of the host. Microbiota communicate with different organs of the organism by synthesizing hormones and regulating body activity. The interaction of the central nervous system (CNS) and gut signaling pathways includes chemical, neural immune and endocrine routes. Alteration or dysbiosis in the gut microbiota leads to different gastrointestinal tract disorders that ultimately impact host physiology because of the abnormal microbial metabolites that stimulate and trigger different physiologic reactions in the host body. Intestinal dysbiosis leads to a change in the bidirectional relationship between the CNS and GM, which is linked to the pathogenesis of neurodevelopmental and neurological disorders. Increasing preclinical and clinical studies/evidence indicate that gut microbes are a possible susceptibility factor for the progression of neurological disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and autism spectrum disorder (ASD). In this review, we discuss the crucial connection between the gut microbiota and the central nervous system, the signaling pathways of multiple biological systems and the contribution of gut microbiota-related neurological disorders.

Gut vascular barrier in the pathogenesis and resolution of Crohn's disease: A novel link from origination to therapy

The gut vascular barrier (GVB) is the deepest layer of the gut barrier. It mainly comprised gut vascular endothelial cells, enteric glial cells, and pericytes. The GVB facilitates nutrient absorption and blocks bacterial translocation through its size-restricted permeability. Accumulating evidence suggests that dysfunction of this barrier correlates with several clinical pathologies including Crohn's disease (CD). Significant progress has been made to elucidate the mechanism of GVB dysfunction and to confirm the participation of disrupted GVB in the course of CD. However, further analyses are required to pinpoint the specific roles of GVB in CD pathogenesis. Many preclinical models and clinical trials have demonstrated that various agents are effective in protecting the GVB integrity and thus providing a potential CD treatment strategy. Through this review, we established a systemic understanding of the role of GVB in CD pathogenesis and provided novel insights for GVB-targeting strategies in CD treatment.

Enteric glia at center stage of inflammatory bowel disease

Although our understanding of the pathophysiology of inflammatory bowel disease (IBD) is increasing, the expanding body of knowledge does not simplify the equation but rather reveals diverse, interconnected, and complex mechanisms in IBD. In addition to immune overactivation, defects in intestinal epithelial barrier (IEB) functioning, dysbiosis, and structural and functional abnormalities of the enteric nervous system are emerging as new elements contributing to the development of IBD. In addition to molecular changes in IBD, enteric glia from patients with Crohn's disease (CD) exhibits the inability to strengthen the IEB; these defects are not observed in patients with ulcerative colitis. In addition, there is a growing body of work describing that enteric glia interacts with not only enterocytes and enteric neurons but also other local cellular neighbours. Thus, because of their functions as connectors and regulators of immune cells, IEB, and microbiota, enteric glia could be the keystone of digestive homeostasis that is lacking in patients with CD.

Stimulator of interferon genes (STING) expression in the enteric nervous system and contributions of glial STING in disease

BACKGROUND

Appropriate host-microbe interactions are essential for enteric glial development and subsequent gastrointestinal function, but the potential mechanisms of microbe-glial communication are unclear. Here, we tested the hypothesis that enteric glia express the pattern recognition receptor stimulator of interferon genes (STING) and communicate with the microbiome through this pathway to modulate gastrointestinal inflammation.

METHODS

In situ transcriptional labeling and immunohistochemistry were used to examine STING and IFNβ expression in enteric neurons and glia. Glial-STING KO mice (Sox10CreERT2+/- ;STINGfl/fl ) and IFNβ ELISA were used to characterize the role of enteric glia in canonical STING activation. The role of glial STING in gastrointestinal inflammation was assessed in the 3% DSS colitis model.

RESULTS

Enteric glia and neurons express STING, but only enteric neurons express IFNβ. While both the myenteric and submucosal plexuses produce IFNβ with STING activation, enteric glial STING plays a minor role in its production and seems more involved in autophagy processes. Furthermore, deleting enteric glial STING does not affect weight loss, colitis severity, or neuronal cell proportions in the DSS colitis model.

CONCLUSION

Taken together, our data support canonical roles for STING and IFNβ signaling in the enteric nervous system through enteric neurons but that enteric glia do not use these same mechanisms. We propose that enteric glial STING may utilize alternative signaling mechanisms and/or is only active in particular disease conditions. Regardless, this study provides the first glimpse of STING signaling in the enteric nervous system and highlights a potential avenue of neuroglial-microbial communication.

Signalling cognition: the gut microbiota and hypothalamic-pituitary-adrenal axis

Cognitive function in humans depends on the complex and interplay between multiple body systems, including the hypothalamic-pituitary-adrenal (HPA) axis. The gut microbiota, which vastly outnumbers human cells and has a genetic potential that exceeds that of the human genome, plays a crucial role in this interplay. The microbiota-gut-brain (MGB) axis is a bidirectional signalling pathway that operates through neural, endocrine, immune, and metabolic pathways. One of the major neuroendocrine systems responding to stress is the HPA axis which produces glucocorticoids such as cortisol in humans and corticosterone in rodents. Appropriate concentrations of cortisol are essential for normal neurodevelopment and function, as well as cognitive processes such as learning and memory, and studies have shown that microbes modulate the HPA axis throughout life. Stress can significantly impact the MGB axis via the HPA axis and other pathways. Animal research has advanced our understanding of these mechanisms and pathways, leading to a paradigm shift in conceptual thinking about the influence of the microbiota on human health and disease. Preclinical and human trials are currently underway to determine how these animal models translate to humans. In this review article, we summarize the current knowledge of the relationship between the gut microbiota, HPA axis, and cognition, and provide an overview of the main findings and conclusions in this broad field.

Enteric glia: genomically open, poised, and ready to make neurons

The heterogeneity and multiple functions of enteric glia have recently been recognized. Guyer et al. have now confirmed the neurogenetic potential of enteric glial cells and have also found that some have an open chromatin configuration, suggesting that some glial cells are poised and ready to differentiate into neurons.

Mini-review: Interaction between intestinal microbes and enteric glia in health and disease

Enteric glia are a unique population of peripheral neuroglia associated with the enteric nervous system (ENS) throughout the digestive tract. The emerging data from the latest glial biology studies unveiled enteric glia as a heterogenic population with plastic and adaptative abilities that display phenotypic and functional changes upon distinct extrinsic cues. This aspect is essential in the dynamic signaling that enteric glia engage with neurons and other neighboring cells within the intestinal wall, such as epithelial, endocrine, and immune cells to maintain local homeostasis. Likewise, enteric glia sense signals from luminal microbes, although the extent of this active communication is still unclear. In this minireview, we discuss the recent findings that support glia-microbes crosstalk in the intestine in health and disease, pointing out the critical aspects that require further investigation.

Beyond the Microbiota: Understanding the Role of the Enteric Nervous System in Parkinson's Disease from Mice to Human

The enteric nervous system (ENS) is a nerve network composed of neurons and glial cells that regulates the motor and secretory functions of the gastrointestinal (GI) tract. There is abundant evidence of mutual communication between the brain and the GI tract. Dysfunction of these connections appears to be involved in the pathophysiology of Parkinson's disease (PD). Alterations in the ENS have been shown to occur very early in PD, even before central nervous system (CNS) involvement. Post-mortem studies of PD patients have shown aggregation of α-synuclein (αS) in specific subtypes of neurons in the ENS. Subsequently, αS spreads retrogradely in the CNS through preganglionic vagal fibers to this nerve's dorsal motor nucleus (DMV) and other central nervous structures. Here, we highlight the role of the ENS in PD pathogenesis based on evidence observed in animal models and using a translational perspective. While acknowledging the putative role of the microbiome in the gut-brain axis (GBA), this review provides a comprehensive view of the ENS not only as a "second brain", but also as a window into the "first brain", a potentially crucial element in the search for new therapeutic approaches that can delay and even cure the disease.

Plp1 in the enteric nervous system is preferentially expressed during early postnatal development in mouse as DM20, whose expression appears reliant on an intronic enhancer

Recently, the myelin proteolipid protein gene (Plp1) was shown to be expressed in the glia of the enteric nervous system (ENS) in mouse. However, beyond this, not much is known about its expression in the intestine. To address this matter, we investigated Plp1 expression at the mRNA and protein levels in the intestine of mice at different ages (postnatal days 2, 9, 21, and 88). In this study, we show that Plp1 expression preferentially occurs during early postnatal development, primarily as the DM20 isoform. Western blot analysis indicated that DM20 migrated according to its formula weight when isolated from the intestine. However, mobilities of both PLP and DM20 were faster than expected when procured from the brain. The 6.2hPLP(+)Z/FL transgene, which uses the first half of the human PLP1 gene to drive expression of a lacZ reporter gene, recapitulated the developmental pattern observed with the native gene in the intestine, indicating that it can be used as a proxy for Plp1 gene expression. As such, the relative levels of β-galactosidase (β-gal) activity emanating from the 6.2hPLP(+)Z/FL transgene suggest that Plp1 expression is highest in the duodenum, and decreases successively along the segments, toward the colon. Moreover, removal of the wmN1 enhancer region from the transgene (located within Plp1 intron 1) resulted in a dramatic reduction in both transgene mRNA levels and β-gal activity in the intestine, throughout development, suggesting that this region contains a regulatory element crucial for Plp1 expression. This is consistent with earlier studies in both the central and peripheral nervous systems, indicating that it may be a common (if not universal) means by which Plp1 gene expression is governed.

Study of tumor necrosis factor receptor in the inflammatory bowel disease

Ulcerative colitis (UC) and Crohn’s disease (CD) are part of Inflammatory Bowel Diseases (IBD) and have pathophysiological processes such as bowel necrosis and enteric neurons and enteric glial cells. In addition, the main inflammatory mediator is related to the tumor necrosis factor-alpha (TNF-α). TNF-α is a me-diator of the intestinal inflammatory processes, thus being one of the main cytokines involved in the pathogenesis of IBD, however, its levels, when measured, are present in the serum of patients with IBD. In addition, TNF-α plays an important role in promoting inflammation, such as the production of interleukins (IL), for instance IL-1β and IL-6. There are two receptors for TNF as following: The tumor necrosis factor 1 receptor (TNFR1); and the tumor necrosis factor 2 receptor (TNFR2). They are involved in the pathogenesis of IBD and their receptors have been detected in IBD and their expression is correlated with disease activity. The soluble TNF form binds to the TNFR1 receptor with, and its activation results in a signaling cascade effects such as apoptosis, cell proliferation and cytokine secretion. In contrast, the transmembrane TNF form can bind both to TNFR1 and TNFR2. Recent studies have suggested that TNF-α is one of the main pro-inflammatory cytokines involved in the pathogenesis of IBD, since TNF levels are present in the serum of both patients with UC and CD. Intravenous and subcutaneous biologics targeting TNF-α have revolutionized the treatment of IBD, thus becoming the best available agents to induce and maintain IBD remission. The application of antibodies aimed at neutralizing TNF-α in patients with IBD that induce a satisfactory clinical response in up to 60% of patients, and also induced long-term maintenance of disease remission in most patients. It has been suggested that anti-TNF-α agents inactivate the pro-inflammatory cytokine TNF-α by direct neutralization, i.e., resulting in suppression of inflammation. However, anti-TNF-α antibodies perform more complex functions than a simple blockade.

Probiotics therapy show significant improvement in obesity and neurobehavioral disorders symptoms

Obesity is a complex metabolic disease, with cognitive impairment being an essential complication. Gut microbiota differs markedly between individuals with and without obesity. The microbial-gut-brain axis is an important pathway through which metabolic factors, such as obesity, affect the brain. Probiotics have been shown to alleviate symptoms associated with obesity and neurobehavioral disorders. In this review, we evaluated previously published studies on the effectiveness of probiotic interventions in reducing cognitive impairment, depression, and anxiety associated with obesity or a high-fat diet. Most of the probiotics studied have beneficial health effects on obesity-induced cognitive impairment and anxiety. They positively affect immune regulation, the hypothalamic-pituitary-adrenal axis, hippocampal function, intestinal mucosa protection, and glucolipid metabolism regulation. Probiotics can influence changes in the composition of the gut microbiota and the ratio between various flora. However, probiotics should be used with caution, particularly in healthy individuals. Future research should further explore the mechanisms underlying the gut-brain axis, obesity, and cognitive function while overcoming the significant variation in study design and high risk of bias in the current evidence.

Role of stimulator of interferon genes (STING) in the enteric nervous system in health and disease

Stimulator of Interferon Genes (STING) is a crucial protein that controls the immune system's reaction to bacterial and viral infections. As a pattern-recognition receptor, STING is found in immune cells as well as in neurons and glia in the enteric nervous system (ENS). Recent studies have linked STING to the pathogenesis of several neurological disorders like multiple sclerosis (MS), Alzheimer's disease (AD), and gastrointestinal disorders, including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), which are characterized by chronic inflammation and dysregulation of the enteric nervous system (ENS) in the digestive tract. STING plays a crucial role in the pathway that induces the production of interferon in response to viral infection in the central nervous system (CNS). A new study by Dharshika et al. in the current issue of Neurogastroenterology and Motility has demonstrated distinct roles for STING in enteric neurons and glia, namely activation of STING leads to IFN-β production in enteric neurons but not in glia and reducing STING activation in enteric glia does not modulate the severity of Dextran sulfate sodium (DSS) colitis or subsequent loss of enteric neurons. Rather, the role of STING in enteric glia is related to enhancing autophagy. STING can influence gastrointestinal motility and barrier function and therefore be involved in the pathophysiology of IBS and IBD. This mini review highlights the current knowledge of STING in the pathophysiology of CNS and gastrointestinal diseases as well as these newly uncovered roles STING in enteric neurons and glia.

Role of herbal medicine and gut microbiota in the prevention and treatment of obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Obesity is a common metabolic dysfunction disease, which is highly correlated with the homeostasis of gut microbiota (GM). The dysregulation of GM on energy metabolism, immune response, insulin resistance and endogenous metabolites (e.g., short chain fatty acids and secondary bile acids) can affect the occurrence and development of obesity. Herbal medicine (HM) has particular advantages and definite therapeutic effects in the prevention and treatment of obesity, but its underlying mechanism is not fully clear.

AIM OF THE STUDY

In this review, the representative basic and clinical anti-obesity studies associated with the homeostasis of GM regulated by HM including active components, single herb and herbal formulae were summarized and discussed. We aim to provide a state of art reference for the mechanism research of HM in treating obesity and the further development of new anti-obesity drugs.

MATERIALS AND METHODS

The relevant information was collected by searching keywords (obesity, herbal medicine, prescriptions, mechanism, GM, short chain fatty acids, etc.) from scientific databases (CNKI, PubMed, SpringerLink, Web of Science, SciFinder, etc.).

RESULTS

GM dysbiosis did occur in obese patients and mice, whiles the intervention of GM could ameliorate the condition of obesity. HM (e.g., berberine, Ephedra sinica, Rehjnannia glutinosa, and Buzhong Yiqi prescription) has been proved to possess a certain regulation on GM and an explicit effect on obesity, but the exact mechanism of HM in improving obesity by regulating GM remains superficial.

CONCLUSION

GM is involved in HM against obesity, and GM can be a novel therapeutic target for treating obesity.

The enteric nervous system

Of all the organ systems in the body, the gastrointestinal tract is the most complicated in terms of the numbers of structures involved, each with different functions, and the numbers and types of signaling molecules utilized. The digestion of food and absorption of nutrients, electrolytes, and water occurs in a hostile luminal environment that contains a large and diverse microbiota. At the core of regulatory control of the digestive and defensive functions of the gastrointestinal tract is the enteric nervous system (ENS), a complex system of neurons and glia in the gut wall. In this review, we discuss 1) the intrinsic neural control of gut functions involved in digestion and 2) how the ENS interacts with the immune system, gut microbiota, and epithelium to maintain mucosal defense and barrier function. We highlight developments that have revolutionized our understanding of the physiology and pathophysiology of enteric neural control. These include a new understanding of the molecular architecture of the ENS, the organization and function of enteric motor circuits, and the roles of enteric glia. We explore the transduction of luminal stimuli by enteroendocrine cells, the regulation of intestinal barrier function by enteric neurons and glia, local immune control by the ENS, and the role of the gut microbiota in regulating the structure and function of the ENS. Multifunctional enteric neurons work together with enteric glial cells, macrophages, interstitial cells, and enteroendocrine cells integrating an array of signals to initiate outputs that are precisely regulated in space and time to control digestion and intestinal homeostasis.

Lasting consequences on physiology and social behavior following cesarean delivery in prairie voles

Cesarean delivery is associated with diminished plasma levels of several 'birth-signaling' hormones, such as oxytocin and vasopressin. These same hormones have been previously shown to exert organizational effects when acting in early life. For example, our previous work found a broadly gregarious phenotype in prairie voles exposed to oxytocin at birth. Meanwhile, cesarean delivery has been previously associated with changes in social behavior and metabolic processes related to oxytocin and vasopressin. In the present study, we investigated the long-term neurodevelopmental consequences of cesarean delivery in prairie voles. After cross-fostering, vole pups delivered either via cesarean or vaginal delivery were studied throughout development. Cesarean-delivered pups responded to isolation differently in terms of their vocalizations (albeit in opposite directions in the two experiments), huddled in less cohesive groups under warmed conditions, and shed less heat. As young adults, we observed no differences in anxiety-like or alloparental behavior. However, in adulthood, cesarean-delivered voles of both sexes failed to form partner preferences with opposite sex conspecifics. In a follow-up study, we replicated this deficit in partner-preference formation among cesarean-delivered voles and were able to normalize pair-bonding behavior by treating cesarean-delivered vole pups with oxytocin (0.25 mg/kg) at delivery. Finally, we detected minor differences in regional oxytocin receptor expression within the brains of cesarean-delivered voles, as well as microbial composition of the gut. Gene expression changes in the gut epithelium indicated that cesarean-delivered male voles have altered gut development. These results speak to the possibility of unintended developmental consequences of cesarean delivery, which currently accounts for 32.9 % of deliveries in the U.S. and suggest that further research should be directed at whether hormone replacement at delivery influences behavioral outcomes in later life.