Opening the doors of precision medicine: novel tools to assess intestinal barrier in inflammatory bowel disease and colitis-associated neoplasia.

Mounting evidence underscores the pivotal role of the intestinal barrier and its convoluted network with diet and intestinal microbiome in the pathogenesis of inflammatory bowel disease (IBD) and colitis-associated colorectal cancer (CRC). Moreover, the bidirectional association of the intestinal barrier with the liver and brain, known as the gut-brain axis, plays a crucial role in developing complications, including extraintestinal manifestations of IBD and CRC metastasis. Consequently, barrier healing represents a crucial therapeutic target in these inflammatory-dependent disorders, with barrier assessment predicting disease outcomes, response to therapy and extraintestinal manifestations.New advanced technologies are revolutionising our understanding of the barrier paradigm, enabling the accurate assessment of the intestinal barrier and aiding in unravelling the complexity of the gut-brain axis. Cutting-edge endoscopic imaging techniques, such as ultra-high magnification endocytoscopy and probe-based confocal laser endomicroscopy, are new technologies allowing real-time exploration of the 'cellular' intestinal barrier. Additionally, novel advanced spatial imaging technology platforms, including multispectral imaging, upconversion nanoparticles, digital spatial profiling, optical spectroscopy and mass cytometry, enable a deep and comprehensive assessment of the 'molecular' and 'ultrastructural' barrier. In this promising landscape, artificial intelligence plays a pivotal role in standardising and integrating these novel tools, thereby contributing to barrier assessment and prediction of outcomes.Looking ahead, this integrated and comprehensive approach holds the promise of uncovering new therapeutic targets, breaking the therapeutic ceiling in IBD. Novel molecules, dietary interventions and microbiome modulation strategies aim to restore, reinforce, or modulate the gut-brain axis. These advancements have the potential for transformative and personalised approaches to managing IBD.

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.

Social anxiety disorder-associated gut microbiota increases social fear.

Social anxiety disorder (SAD) is a crippling psychiatric disorder characterized by intense fear or anxiety in social situations and their avoidance. However, the underlying biology of SAD is unclear and better treatments are needed. Recently, the gut microbiota has emerged as a key regulator of both brain and behaviour, especially those related to social function. Moreover, increasing data supports a role for immune function and oxytocin signalling in social responses. To investigate whether the gut microbiota plays a causal role in modulating behaviours relevant to SAD, we transplanted the microbiota from SAD patients, which was identified by 16S rRNA sequencing to be of a differential composition compared to healthy controls, to mice. Although the mice that received the SAD microbiota had normal behaviours across a battery of tests designed to assess depression and general anxiety-like behaviours, they had a specific heightened sensitivity to social fear, a model of SAD. This distinct heightened social fear response was coupled with changes in central and peripheral immune function and oxytocin expression in the bed nucleus of the stria terminalis. This work demonstrates an interkingdom basis for social fear responses and posits the microbiome as a potential therapeutic target for SAD.

Decoding the neurocircuitry of gut feelings: Region-specific microbiome-mediated brain alterations.

Research in the last decade has unveiled a crucial role for the trillions of microorganisms that reside in the gut in influencing host neurodevelopment across the lifespan via the microbiota-gut-brain axis. Studies have linked alterations in the composition, complexity, and diversity of the gut microbiota to changes in behaviour including abnormal social interactions, cognitive deficits, and anxiety- and depressive-like phenotypes. Moreover, the microbiota has been linked with neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Interestingly, there appears to be specific brain regions governing the neurocircuitry driving higher cognitive function that are susceptible to influence from manipulations to the host microbiome. This review will aim to elucidate the region-specific effects mediated by the gut microbiota, with a focus on translational animal models and some existing human neuroimaging data. Compelling preclinical evidence suggests disruption to normal microbiota-gut-brain signalling can have detrimental effects on the prefrontal cortex, amygdala, hippocampus, hypothalamus, and striatum. Furthermore, human neuroimaging studies have unveiled a role for the microbiota in mediating functional connectivity and structure of specific brain regions that can be traced back to neurocognition and behavioural output. Understanding these microbiota-mediated changes will aid in identifying unique therapeutic targets for treating neurological disorders associated with these regions.

The gut microbiota is important for the maintenance of blood-cerebrospinal fluid barrier integrity.

The gut microbiota communicates with the brain through several pathways including the vagus nerve, immune system, microbial metabolites and through the endocrine system. Pathways along the humoral/immune gut microbiota-brain axis are composed of a series of vascular and epithelial barriers including the intestinal epithelial barrier, gut-vascular barrier, blood-brain barrier and blood-cerebrospinal fluid barrier. Of these barriers, the relationship between the gut microbiota and blood-cerebrospinal fluid barrier is yet to be fully defined. Here, using a germ-free mouse model, we aimed to assess the relationship between the gut microbiota and the integrity of the blood-cerebrospinal fluid barrier, which is localized to the choroid plexus epithelium. Using confocal microscopy, we visualized the tight junction protein zonula occludens-1, an integral aspect of choroid plexus integrity, as well as the choroid plexus fenestrated capillaries. Quantification of tight junction proteins via network analysis led to the observation that there was a decrease in the zonula occludens-1 network organization in germ-free mice; however, we did not observe any differences in capillary structure. Taken together, these data indicate that the blood-cerebrospinal fluid barrier is another barrier along the gut microbiota-brain axis. Future studies are required to elucidate its relative contribution in signalling from microbiota to the brain.

Microbial-derived metabolites induce actin cytoskeletal rearrangement and protect blood-brain barrier function.

The gut microbiota influences host brain function, but the underlying gut-brain axis connections and molecular processes remain unclear. One pathway along this bidirectional communication system involves circulating microbially derived metabolites, such as short-chain fatty acids (SCFAs), which include butyrate and propionate. Brain endothelium is the main interface of communication between circulating signals and the brain, and it constitutes the main component of the blood-brain barrier (BBB). Here, we used a well-established in vitro BBB model treated with physiologically relevant concentrations of butyrate and propionate with and without lipopolysaccharide (LPS) to examine the effects of SCFAs on the actin cytoskeleton and tight junction protein structure. Both SCFAs induced distinct alterations to filamentous actin directionality. SCFAs also increased tight junction protein spikes and protected from LPS-induced tight-junction mis-localization, improved BBB integrity, and modulated mitochondrial network dynamics. These findings identify the actin cytoskeletal dynamics as another target further illuminating how SCFAs can influence BBB physiology.

The blood-brain barrier in aging and neurodegeneration.

The blood-brain barrier (BBB) is vital for maintaining brain homeostasis by enabling an exquisite control of exchange of compounds between the blood and the brain parenchyma. Moreover, the BBB prevents unwanted toxins and pathogens from entering the brain. This barrier, however, breaks down with age and further disruption is a hallmark of many age-related disorders. Several drugs have been explored, thus far, to protect or restore BBB function. With the recent connection between the BBB and gut microbiota, microbial-derived metabolites have been explored for their capabilities to protect and restore BBB physiology. This review, will focus on the vital components that make up the BBB, dissect levels of disruption of the barrier, and discuss current drugs and therapeutics that maintain barrier integrity and the recent discoveries of effects microbial-derived metabolites have on BBB physiology.

Short chain fatty acids: Microbial metabolites for gut-brain axis signalling.

The role of the intestinal microbiota as a regulator of gut-brain axis signalling has risen to prominence in recent years. Understanding the relationship between the gut microbiota, the metabolites it produces, and the brain will be critical for the subsequent development of new therapeutic approaches, including the identification of novel psychobiotics. A key focus in this regard have been the short-chain fatty acids (SCFAs) produced by bacterial fermentation of dietary fibre, which include butyrate, acetate, and propionate. Ongoing research is focused on the entry of SCFAs into systemic circulation from the gut lumen, their migration to cerebral circulation and across the blood brain barrier, and their potential to exert acute and chronic effects on brain structure and function. This review aims to discuss our current mechanistic understanding of the direct and indirect influence that SCFAs have on brain function, behaviour and physiology, which will inform future microbiota-targeted interventions for brain disorders.

Prevalence and co-occurrence of lifestyle risk factors for non-communicable diseases according to sociodemographic characteristics among adults Chilean residents.

To examine the prevalence and co-occurrence of lifestyle risk factors for non-communicable diseases (NCDs) according to sociodemographic characteristics in Chilean residents. A cross-sectional study based on data from 5995 adults from the Chilean National Health Survey. The lifestyle risk factors included were physical inactivity, tobacco consumption, alcohol consumption, low fruits and vegetable consumption, and overweight/obesity. The most frequent risk factor was overweight/obesity (75.6%), followed by alcohol consumption (74.8%), low fruits and vegetable consumption (51.7%), physical inactivity (36.3%), and tobacco consumption (27.9%). Only 1.0% of the participants did not present any risk factor, while 9.6%, 30.4%, 34.0%, 20.3%, and 4.7% accumulated one, two, three, four, and five risk factors. Men (OR 1.56; 95% CI 1.18; 2.04), people who have secondary education (OR 1.59; 95% CI 1.20; 2.10), and those with lower household income (OR 1.39; 95% CI 1.09; 1.59) had higher odds of three or more risk factors. Associations were inverse for older adults (OR 0.57; 95% CI 0.41; 0.79) and rural geographic areas (OR 0.77; 95% CI 0.67; 0.89). The prevalence of risk factors for NCDs is fairly high in Chilean residents. Interventions may need to target these co-occurrences rather than emphasizing individual risk factors for NCDs. Interventions could further consider these co-occurrences as a potential target for population stratification.

Advances in the Design of (Nano)Formulations for Delivery of Antisense Oligonucleotides and Small Interfering RNA: Focus on the Central Nervous System.

RNA-based therapeutics have emerged as one of the most powerful therapeutic options used for the modulation of gene/protein expression and gene editing with the potential to treat neurodegenerative diseases. However, the delivery of nucleic acids to the central nervous system (CNS), in particular by the systemic route, remains a major hurdle. This review will focus on the strategies for systemic delivery of therapeutic nucleic acids designed to overcome these barriers. Pathways and mechanisms of transport across the blood-brain barrier which could be exploited for delivery are described, focusing in particular on smaller nucleic acids including antisense oligonucleotides (ASOs) and small interfering RNA (siRNA). Approaches used to enhance delivery including chemical modifications, nanocarrier systems, and target selection (cell-specific delivery) are critically analyzed. Learnings achieved from a comparison of the successes and failures reported for CNS delivery of ASOs versus siRNA will help identify opportunities for a wider range of nucleic acids and accelerate the clinical translation of these innovative therapies.

Blood-Brain Barrier Dynamics to Maintain Brain Homeostasis.

The blood-brain barrier (BBB) is a dynamic platform for exchange of substances between the blood and the brain parenchyma, and it is an essential functional gatekeeper for the central nervous system (CNS). While it is widely recognized that BBB disruption is a hallmark of several neurovascular pathologies, an aspect of the BBB that has received somewhat less attention is the dynamic modulation of BBB tightness to maintain brain homeostasis in response to extrinsic environmental factors and physiological changes. In this review, we summarize how BBB integrity adjusts in critical stages along the life span, as well as how BBB permeability can be altered by common stressors derived from nutritional habits, environmental factors and psychological stress.

Otic Neurogenesis Is Regulated by TGFß in a Senescence-Independent Manner.

Cellular senescence has classically been associated with aging. Intriguingly, recent studies have also unraveled key roles for senescence in embryonic development, regeneration, and reprogramming. Developmental senescence has been reported during embryonic development in different organisms and structures, such as the endolymphatic duct during inner ear development of mammals and birds. However, there is no study addressing the possible role of senescence on otic neurogenesis. TGFß/SMAD is the best-known pathway linked to the induction of developmentally programmed cell senescence. Here, we studied if TGFß2 induces cellular senescence during acoustic-vestibular-ganglion (AVG) formation. Using organotypic cultures of AVG, and characterizing different stages of otic neurogenesis in the presence of TGFß2 and a selective TGF-ß receptor type-I inhibitor, we show that TGFß2 exerts a powerful action in inner ear neurogenesis but, contrary to what we recently observed during endolymphatic duct development, these actions are independent of cellular senescence. We show that TGFß2 reduces proliferation, and induces differentiation and neuritogenesis of neuroblasts, without altering cell death. Our studies highlight the roles of TGFß2 and cellular senescence in the precise regulation of cell fate within the developing inner ear and its different cell types, being their mechanisms of action highly cell-type dependent.

Neurovascular Interactions in the Nervous System.

Molecular cross talk between the nervous and vascular systems is necessary to maintain the correct coupling of organ structure and function. Molecular pathways shared by both systems are emerging as major players in the communication of the neuronal compartment with the endothelium. Here we review different aspects of this cross talk and how vessels influence the development and homeostasis of the nervous system. Beyond the classical role of the vasculature as a conduit to deliver oxygen and metabolites needed for the energy-demanding neuronal compartment, vessels emerge as powerful signaling systems that control and instruct a variety of cellular processes during the development of neurons and glia, such as migration, differentiation, and structural connectivity. Moreover, a broad spectrum of mild to severe vascular dysfunctions occur in various pathologies of the nervous system, suggesting that mild structural and functional changes at the neurovascular interface may underlie cognitive decline in many of these pathological conditions.

TGFß2-induced senescence during early inner ear development.

Embryonic development requires the coordinated regulation of apoptosis, survival, autophagy, proliferation and differentiation programs. Senescence has recently joined the cellular processes required to master development, in addition to its well-described roles in cancer and ageing. Here, we show that senescent cells are present in a highly regulated temporal pattern in the developing vertebrate inner ear, first, surrounding the otic pore and, later, in the otocyst at the endolymphatic duct. Cellular senescence is associated with areas of increased apoptosis and reduced proliferation consistent with the induction of the process when the endolymphatic duct is being formed. Modulation of senescence disrupts otic vesicle morphology. Transforming growth factor beta (TGFß) signaling interacts with signaling pathways elicited by insulin-like growth factor type 1 (IGF-1) to jointly coordinate cellular dynamics required for morphogenesis and differentiation. Taken together, these results show that senescence is a natural occurring process essential for early inner ear development.

Early psychosis detection program in Chile: A first step for the South American challenge in psychosis research.

AIM: Early detection and intervention (EDI) is a main challenge in psychosis research. The Chilean schizophrenia (SZ) national program has universal support and treatment by law for all SZ patients, but this does not yet extend to earlier stages of illness. Therefore, we have piloted an ultra-high risk (UHR) program to demonstrate the utility and feasibility of this public health approach in Chile. METHODS: We introduce "The University of Chile High-risk Intervention Program," which is the first national EDI program for UHR youths. Longitudinal follow-up included clinical and cognitive assessments, and monitoring of physiological sensory and cognitive indices, through electroencephalographic techniques. RESULTS: We recruited 27 UHR youths over 2 years. About 92.6% met criteria for attenuated psychosis syndrome (APS). Mean Scale of Psychosis-Risk Symptoms (SOPS) ratings in the cohort were 6.9 (SD 4.6) for positive, 9.1 (SD 8.3) for negative, 5.4 (SD 5.3) for disorganized and 6.3 (SD 4.1) for general symptoms. About 14.8% met criteria for comorbid anxiety disorders and 44.4% for mood disorders. Most participants received cognitive behavioural therapy (62.9%) and were prescribed low dose antipsychotics (85.2%). The transition rate to psychosis was 22% within 2 years. CONCLUSIONS: We describe our experience in establishing the first EDI program for UHR subjects in Chile. Our cohort is similar in profile and risk to those identified in higher-income countries. We will extend our work to further optimize psychosocial and preventive interventions, to promote its inclusion in the Chilean SZ national program and to establish a South American collaboration network for SZ research.

Endothelial Dab1 signaling orchestrates neuro-glia-vessel communication in the central nervous system.

The architecture of the neurovascular unit (NVU) is controlled by the communication of neurons, glia, and vascular cells. We found that the neuronal guidance cue reelin possesses proangiogenic activities that ensure the communication of endothelial cells (ECs) with the glia to control neuronal migration and the establishment of the blood-brain barrier in the mouse brain. Apolipoprotein E receptor 2 (ApoER2) and Disabled1 (Dab1) expressed in ECs are required for vascularization of the retina and the cerebral cortex. Deletion of Dab1 in ECs leads to a reduced secretion of laminin-α4 and decreased activation of integrin-ß1 in glial cells, which in turn control neuronal migration and barrier properties of the NVU. Thus, reelin signaling in the endothelium is an instructive and integrative cue essential for neuro-glia-vascular communication.

Autophagy in the Vertebrate Inner Ear.

Autophagy is a conserved catabolic process that results in the lysosomal degradation of cell components. During development, autophagy is associated with tissue and organ remodeling, and under physiological conditions it is tightly regulated as it plays a housekeeping role in removing misfolded proteins and damaged organelles. The vertebrate inner ear is a complex sensory organ responsible for the perception of sound and for balance. Cell survival, death and proliferation, as well as cell fate specification and differentiation, are processes that are strictly coordinated during the development of the inner ear in order to generate the more than a dozen specialized cell types that constitute this structure. Here, we review the existing evidence that implicates autophagy in the generation of the vertebrate inner ear. At early stages of chicken otic development, inhibiting autophagy impairs neurogenesis and causes aberrant otocyst morphogenesis. Autophagy provides energy for the clearing of dying cells and it favors neuronal differentiation. Moreover, autophagy is required for proper vestibular development in the mouse inner ear. The autophagy-related genes Becn1, Atg4g, Atg5, and Atg9, are expressed in the inner ear from late developmental stages to adulthood, and Atg4b mutants show impaired vestibular behavior associated to defects in otoconial biogenesis that are also common to Atg5 mutants. Autophagic flux appears to be age-regulated, augmenting from perinatal stages to young adulthood in mice. This up-regulation is concomitant with the functional maturation of the hearing receptor. Hence, autophagy can be considered an intracellular pathway fundamental for in vertebrate inner ear development and maturation.

Hypovitaminosis D correction and high-sensitivity C-reactive protein levels in hypertensive adults.

CONTEXT: Hypovitaminosis D has been implicated as a possible risk factor for the development of cardiovascular disease. High-sensitivity C-reactive protein (hs-CRP) has been one of the most extensively studied biomarkers for cardiovascular inflammation as an indicator of disease and event risk, independent of traditional risk factors. To date, it is unclear if correction of hypovitaminosis D leads to a reduction of hs-CRP in human subjects. OBJECTIVES: To assess laboratory validity of 25-hydroxyvita-min D (25-OH-vitamin D) and hs-CRP measurements and to determine whether hs-CRP levels in adults with well-controlled hypertension and comorbid low vitamin D levels changed after hypovitaminosis D correction to a serum 25-OH-vitamin D level greater than 30 ng/mL. DESIGN: Prospective study using an unblinded design. RESULTS: One hundred eight subjects who were vitamin D insufficient or deficient completed this study. The mean 25-OH-vitamin D level was 20.07 ng/mL before treatment and 43.92 ng/mL after treatment. Posttreatment vitamin D levels were in the normal range for 91% of the subjects. No statistically significant changes in hs-CRP level were detected after the vitamin D treatment was administered and a posttreatment vitamin D level above 30 ng/mL was confirmed. CONCLUSION: We did not detect a statistically significant difference in hs-CRP after correction of hypovitaminosis D. Twelve weekly oral doses of 50,000 IU of ergocalciferol corrected the hypovitaminosis D in more than 90% of cases.

Early development of the vertebrate inner ear.

This is a review of the biological processes and the main signaling pathways required to generate the different otic cell types, with particular emphasis on the actions of insulin-like growth factor I. The sensory organs responsible of hearing and balance have a common embryonic origin in the otic placode. Lineages of neural, sensory, and support cells are generated from common otic neuroepithelial progenitors. The sequential generation of the cell types that will form the adult inner ear requires the coordination of cell proliferation with cell differentiation programs, the strict regulation of cell survival, and the metabolic homeostasis of otic precursors. A network of intracellular signals operates to coordinate the transcriptional response to the extracellular input. Understanding the molecular clues that direct otic development is fundamental for the design of novel treatments for the protection and repair of hearing loss and balance disorders.