Corticosteroid enhances epithelial barrier function in intestinal organoids derived from patients with Crohn's disease

Navigating the complexities of drug development for inflammatory bowel disease

Inflammatory bowel disease (IBD) - consisting of ulcerative colitis and Crohn's disease - is a complex, heterogeneous, immune-mediated inflammatory condition with a multifactorial aetiopathogenesis. Despite therapeutic advances in this arena, a ceiling effect has been reached with both single-agent monoclonal antibodies and advanced small molecules. Therefore, there is a need to identify novel targets, and the development of companion biomarkers to select responders is vital. In this Perspective, we examine how advances in machine learning and tissue engineering could be used at the preclinical stage where attrition rates are high. For novel agents reaching clinical trials, we explore factors decelerating progression, particularly the decline in IBD trial recruitment, and assess how innovative approaches such as reconfiguring trial designs, harmonizing end points and incorporating digital technologies into clinical trials can address this. Harnessing opportunities at each stage of the drug development process may allow for incremental gains towards more effective therapies.

Translational Utility of Organoid Models for Biomedical Research on Gastrointestinal Diseases

Organoid models have recently been utilized to study 3D human-derived tissue systems to uncover tissue architecture and adult stem cell biology. Patient-derived organoids unambiguously provide the most suitable in vitro system to study disease biology with the actual genetic background. With the advent of much improved and innovative approaches, patient-derived organoids can potentially be used in regenerative medicine. Various human tissues were explored to develop organoids due to their multifold advantage over the conventional in vitro cell line culture approach and in vivo models. Gastrointestinal (GI) tissues have been widely studied to establish organoids and organ-on-chip for screening drugs, nutraceuticals, and other small molecules having therapeutic potential. The function of channel proteins, transporters, and transmembrane proteins was also explained. The successful application of genome editing in organoids using the CRISPR-Cas approach has been reported recently. GI diseases such as Celiac disease (CeD), Inflammatory bowel disease (IBD), and common GI cancers have been investigated using several patient-derived organoid models. Recent advancements on organoid bio-banking and 3D bio-printing contributed significantly in personalized disease management and therapeutics. This article reviews the available literature on investigations and translational applications of patient-derived GI organoid models, notably on elucidating gut-microbial interaction and epigenetic modifications.

Electrochemical peptide-based biosensor for the detection of the inflammatory disease biomarker, interleukin-1beta

This paper reports the development of a highly sensitive and selective electrochemical peptide-based biosensor for the detection of the inflammatory disease biomarker, interleukin-1beta (IL-1β). To this end, flower-like Au-Ag@MoS2-rGO nanocomposites were used as the signal amplification platform to achieve a label-free biosensor with a high sensitivity and selectivity. First, a high-affinity peptide for IL-1β was identified through biopanning with M13 random peptide libraries, and was newly designed by incorporating cysteine at the C-terminus. An IL-1β specific binding peptide was used as the bio-receptor, and the interaction between the IL-1β binding peptide and IL-1β was confirmed via enzyme-linked immunosorbent assay and various physicochemical and electrochemical analyses. Under optimal conditions, the biosensor achieved an ultrasensitive and specific IL-1β detection in a wide linear concentration range of 0-250 ng/mL with a picomolar-level detection limit (∼2.4 pM), low binding constant (∼0.62 pM), and a low coefficient of variation (<1.65 %). The biosensor was successfully utilized for IL-1β determination in the serum of Crohn's disease patients with a good correlation coefficient. In addition, the detection performance was comparable to that of commercially available IL-1β ELISA kit. This indicates that the electrochemical peptide-based biosensor may offer a potentially valuable platform for the clinical diagnosis of various inflammatory disease biomarkers.

The epithelium takes the stage in asthma and inflammatory bowel diseases

The epithelium is a dynamic barrier and the damage to this epithelial layer governs a variety of complex mechanisms involving not only epithelial cells but all resident tissue constituents, including immune and stroma cells. Traditionally, diseases characterized by a damaged epithelium have been considered "immunological diseases," and research efforts aimed at preventing and treating these diseases have primarily focused on immuno-centric therapeutic strategies, that often fail to halt or reverse the natural progression of the disease. In this review, we intend to focus on specific mechanisms driven by the epithelium that ensure barrier function. We will bring asthma and Inflammatory Bowel Diseases into the spotlight, as we believe that these two diseases serve as pertinent examples of epithelium derived pathologies. Finally, we will argue how targeting the epithelium is emerging as a novel therapeutic strategy that holds promise for addressing these chronic diseases.

Hyaluronic Acid-Conjugated Thermoresponsive Polymer-Based Bioformulation Enhanced Wound Healing and Gut Barrier Repair of a TNBS-Induced Colitis Injury Ex Vivo Model in a Dynamic Perfusion Device

Impairment of intestinal epithelium is a typical feature of inflammatory bowel disease (IBD) that causes leakage of bacteria and antigens from the intestinal lumen and thus results in persistent immune activation. Hence, healing and regeneration of the damaged gut mucosa is a promising therapeutic approach to achieve deep remission in IBD. Currently, available systemic therapies have moderate effects and are often associated with numerous side effects and malignancies. In this study, we aimed to develop a topical therapy by chemically conjugating a temperature-responsive polymer, i.e., poly(N-isopropylacrylamide), along with hyaluronic acid to obtain a sprayable therapeutic formulation that upon colon instillation adheres to the damaged gut mucosa due to its temperature-induced phase transition and mucoadhesive properties. An ex vivo adhesion experiment demonstrates that this therapeutic formulation forms a thin physical coating on the mucosal lining at a physiological temperature within 5 min. Physicochemical characterization of (P(NIPAM-co-NTBAM)-HA) established this formulation to be biocompatible, hemo-compatible, and non-immunogenic. Prednisolone was encapsulated within the polymer formulation to achieve maximum therapeutic efficacy in the case of IBD-like conditions as assessed in a custom-fabricated perfusion-based ex vivo model system. Histological analysis suggests that the prednisolone-encapsulated polymer formulation nearly restored the mucosal architecture after 2,4,6-trinitrobenzenesulfonic acid-induced damage. Furthermore, a significant (p ≤ 0.001) increase in mRNA levels of Muc-2 and ZO-1 in treated groups further confirmed the mucosal epithelial barrier restoration.

Arjunolic acid protects the intestinal epithelial barrier, ameliorating Crohn's disease-like colitis by restoring gut microbiota composition and inactivating TLR4 signalling

BACKGROUND AND AIMS

Crohn's disease (CD) is characterized by an overabundance of epithelial cell death and an imbalance in microflora, both of which contribute to the dysfunction of the intestinal barrier. Arjunolic acid (AA) has anti-apoptotic effects and regulates microbiota efficacy. The objective of this study was to assess the impact of the treatment on colitis resembling Crohn's disease, along with exploring the potential underlying mechanism.

METHODS

CD animal models were created using Il-10-/- mice, and the impact of AA on colitis in mice was evaluated through disease activity index, weight fluctuations, pathological examination, and assessment of intestinal barrier function. To clarify the direct role of AA on intestinal epithelial cell apoptosis, organoids were induced by LPS, and TUNEL staining was performed. To investigate the potential mechanisms of AA in protecting the intestinal barrier, various methods including bioinformatics analysis and FMT experiments were employed.

RESULTS

The treatment for AA enhanced the condition of colitis and the function of the intestinal barrier in Il-10-/- mice. This was demonstrated by the amelioration of weight loss, reduction in tissue inflammation score, and improvement in intestinal permeability. Moreover, AA suppressed the apoptosis of intestinal epithelial cells in Il-10-/- mice and LPS-induced colon organoids, while also reducing the levels of Bax and C-caspase-3. In terms of mechanism, AA suppressed the activation of TLR4 signaling in Il-10-/- mice and colon organoids induced by LPS. In addition, AA increased the abundance of short-chain fatty acid-producing bacteria in the stool of Il-10-/- mice, and transplantation of feces from AA-treated mice improved CD-like colitis.

CONCLUSIONS

The results of our study demonstrate that AA has a protective effect on the intestinal barrier in Crohn's disease-like colitis by preventing apoptosis. Additionally, this groundbreaking study reveals the capacity of AA to hinder TLR4 signaling and alter the makeup of the intestinal microbiome. The findings present fresh possibilities for treating individuals diagnosed with Crohn's disease. AA offers a hopeful novel strategy for managing Crohn's disease by obstructing crucial pathways implicated in intestinal inflammation and enhancing the gut microbiota.

Dexamethasone restores TNFα-induced epithelial barrier dysfunction in primary rat alveolar epithelial cells

Alveolar barrier dysfunction is one of the major pathophysiological changes in acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). In ALI/ARDS, tumor necrosis factor-alpha (TNFα) disrupts the barriers of alveolar epithelium and endothelium. Glucocorticoids (GCs) exert anti-inflammatory effects and ameliorate pulmonary edema in ALI/ARDS. However, the involvement of GCs in the restoration of alveolar epithelial barrier dysfunction has not been extensively studied. Here, we elucidated that dexamethasone (Dex) restored TNFα-induced alveolar epithelial barrier dysfunction in vitro using primary rat alveolar epithelial cells isolated from Sprague-Dawley rats. Moreover, Dex promoted the alveolar epithelial cell barrier integrity by initiating GC receptor-mediated signaling via the downregulation of myosin light chain kinase (MLCK) expression and the dephosphorylation of myosin light chain (MLC) 2. Further investigation revealed that Dex enhanced the expression of zonula occludens-1 (ZO-1), a tight junction-related protein, at intercellular junction sites. These findings suggest that GCs strengthen the integrity of the alveolar epithelial barrier in ALI/ARDS via the GR-MLCK-pMLC2 axis.

Cinnamon (Cinnamomum cassia) hot water extract improves inflammation and tight junctions in the intestine in vitro and in vivo

The natural byproduct Cinnamomum cassia was widely used in ancient Asia to cure disease because of its various pharmacological effects. Despite its ethnomedicinal benefits, few studies on the intestinal anti-inflammatory effect of C. cassia have been reported. Therefore, this study aimed to evaluate the potential beneficial effects of C. cassia on the intestine in vitro and in vivo. Herein, the effects of cinnamon hot water extract (CWE) on tight junction (TJ) barrier function, transepithelial electrical resistance, and mRNA expression were confirmed in Caco-2 cells. The CWE treatment groups showed significantly enhanced cell permeability, proinflammatory cytokine mRNA expression, and TJ expression. CWE-treated mice showed an improved histological index and decreased cytokine concentrations compared with those of colitis model mice. These results suggest that CWE alleviated inflammatory damage and improved the TJ barrier, indicating that CWE may be used as a functional food to improve intestinal health.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01292-3.

Human organoids are superior to cell culture models for intestinal barrier research

Loss of intestinal epithelial barrier function is a hallmark in digestive tract inflammation. The detailed mechanisms remain unclear due to the lack of suitable cell-based models in barrier research. Here we performed a detailed functional characterization of human intestinal organoid cultures under different conditions with the aim to suggest an optimized ex-vivo model to further analyse inflammation-induced intestinal epithelial barrier dysfunction. Differentiated Caco2 cells as a traditional model for intestinal epithelial barrier research displayed mature barrier functions which were reduced after challenge with cytomix (TNFα, IFN-γ, IL-1ß) to mimic inflammatory conditions. Human intestinal organoids grown in culture medium were highly proliferative, displayed high levels of LGR5 with overall low rates of intercellular adhesion and immature barrier function resembling conditions usually found in intestinal crypts. WNT-depletion resulted in the differentiation of intestinal organoids with reduced LGR5 levels and upregulation of markers representing the presence of all cell types present along the crypt-villus axis. This was paralleled by barrier maturation with junctional proteins regularly distributed at the cell borders. Application of cytomix in immature human intestinal organoid cultures resulted in reduced barrier function that was accompanied with cell fragmentation, cell death and overall loss of junctional proteins, demonstrating a high susceptibility of the organoid culture to inflammatory stimuli. In differentiated organoid cultures, cytomix induced a hierarchical sequence of changes beginning with loss of cell adhesion, redistribution of junctional proteins from the cell border, protein degradation which was accompanied by loss of epithelial barrier function. Cell viability was observed to decrease with time but was preserved when initial barrier changes were evident. In summary, differentiated intestinal organoid cultures represent an optimized human ex-vivo model which allows a comprehensive reflection to the situation observed in patients with intestinal inflammation. Our data suggest a hierarchical sequence of inflammation-induced intestinal barrier dysfunction starting with loss of intercellular adhesion, followed by redistribution and loss of junctional proteins resulting in reduced barrier function with consecutive epithelial death.

Stem cell-derived intestinal organoids: a novel modality for IBD

The organoids represent one of the greatest revolutions in the biomedical field in the past decade. This three-dimensional (3D) micro-organ cultured in vitro has a structure highly similar to that of the tissue and organ. Using the regeneration ability of stem cells, a 3D organ-like structure called intestinal organoids is established, which can mimic the characteristics of real intestinal organs, including morphology, function, and personalized response to specific stimuli. Here, we discuss current stem cell-based organ-like 3D intestinal models, including understanding the molecular pathophysiology, high-throughput screening drugs, drug efficacy testing, toxicological evaluation, and organ-based regeneration of inflammatory bowel disease (IBD). We summarize the advances and limitations of the state-of-the-art reconstruction platforms for intestinal organoids. The challenges, advantages, and prospects of intestinal organs as an in vitro model system for precision medicine are also discussed. Key applications of stem cell-derived intestinal organoids. Intestinal organoids can be used to model infectious diseases, develop new treatments, drug screens, precision medicine, and regenerative medicine.

Long-Term Use of Proton Pump Inhibitors Disrupts Intestinal Tight Junction Barrier and Exaggerates Experimental Colitis

BACKGROUND

Proton pump inhibitors [PPIs] are widely used to treat a number of gastro-oesophageal disorders. PPI-induced elevation in intragastric pH may alter gastrointestinal physiology. The tight junctions [TJs] residing at the apical intercellular contacts act as a paracellular barrier. TJ barrier dysfunction is an important pathogenic factor in inflammatory bowel disease [IBD]. Recent studies suggest that PPIs may promote disease flares in IBD patients. The role of PPIs in intestinal permeability is not clear.

AIM

The aim of the present study was to study the effect of PPIs on the intestinal TJ barrier function.

METHODS

Human intestinal epithelial cell culture and organoid models and mouse IBD models of dextran sodium sulphate [DSS] and spontaneous enterocolitis in IL-10-/- mice were used to study the role of PPIs in intestinal permeability.

RESULTS

PPIs increased TJ barrier permeability via an increase in a principal TJ regulator, myosin light chain kinase [MLCK] activity and expression, in a p38 MAPK-dependent manner. The PPI-induced increase in extracellular pH caused MLCK activation via p38 MAPK. Long-term PPI administration in mice exaggerated the increase in intestinal TJ permeability and disease severity in two independent models of DSS colitis and IL-10-/- enterocolitis. The TJ barrier disruption by PPIs was prevented in MLCK-/- mice. Human database studies revealed increased hospitalizations associated with PPI use in IBD patients.

CONCLUSIONS

Our results suggest that long-term use of PPIs increases intestinal TJ permeability and exaggerates experimental colitis via an increase in MLCK expression and activity.

A Living Organoid Biobank of Crohn's Disease Patients Reveals Molecular Subtypes for Personalized Therapeutics

Crohn's disease (CD) is a complex, clinically heterogeneous disease of multifactorial origin; there is no perfect pre-clinical model, little insight into the basis for such heterogeneity, and still no cure. To address these unmet needs, we sought to explore the translational potential of adult stem cell-derived organoids that not only retain their tissue identity, but also their genetic and epigenetic disease-driving traits. We prospectively created a biobank of CD patient-derived organoid cultures (PDOs) using biopsied tissues from colons of 34 consecutive subjects representing all clinical subtypes (Montreal Classification B1-B3 and perianal disease). PDOs were generated also from healthy subjects. Comparative gene expression analyses enabled benchmarking of PDOs as tools for modeling the colonic epithelium in active disease and revealed that despite the clinical heterogeneity there are two major molecular subtypes: immune-deficient infectious-CD [IDICD] and stress and senescence-induced fibrostenotic-CD [S2FCD]. The transcriptome, genome and phenome show a surprising degree of internal consistency within each molecular subtype. The spectrum of morphometric, phenotypic, and functional changes within the "living biobank" reveals distinct differences between the molecular subtypes. These insights enabled drug screens that reversed subtype-specific phenotypes, e.g., impaired microbial clearance in IDICD was reversed using agonists for nuclear receptors, and senescence in S2FCD was rectified using senotherapeutics, but not vice versa . Phenotyped-genotyped CD-PDOs may fill the gap between basic biology and patient trials by enabling pre-clinical Phase '0' human trials for personalized therapeutics.

GRAPHIC ABSTRACT

In Brief

This work creates a prospectively biobanked phenotyped-genotyped Crohn's disease patient-derived organoids (CD-PDOs) as platforms for molecular subtyping of disease and for ushering personalized therapeutics.

HIGHLIGHTS

Prospectively biobanked CD-organoids recapitulate the disease epithelium in patientsThe phenome-transcriptome-genome of CD-organoids converge on two molecular subtypesOne subtype shows impaired microbial clearance, another increased cellular senescencePhenotyped-genotyped PDOs are then used for integrative and personalized therapeutics.

Intestinal permeability in patients with IgA nephropathy and other glomerular diseases: an observational study

BACKGROUND

A dysregulated 'gut-kidney axis' may contribute to immunoglobulin A nephropathy (IgAN). We studied whether IgAN patients have disturbed intestinal permeability.

METHODS

In a prospective, cross sectional, pilot study we assessed intestinal permeability in 35 IgAN patients, 18 patients with non-IgAN glomerulonephritides (GNs) and 19 healthy controls. After an overnight fast, trial participants ingested a multi-sugar solution and samples were obtained from 0 to 2, 2 to 5- and 5 to 24-h urine portions. Urinary sugar concentrations were quantified using isocratic ion-exchange high performance liquid chromatography. Indices of small intestinal permeability (0-2-h lactulose/L-rhamnose (L/R) ratio), distal small intestinal and proximal colonic permeability (2-5-h sucralose/erythritol (S/E) ratio) and colonic permeability (5-24-h sucralose/erythritol (S/E) ratio) were evaluated. Associations between groups and indices of intestinal permeability were investigated by a linear mixed model.

RESULTS

Small intestinal permeability (0-2 h L/R-ratio) was significantly increased in patients with glomerular diseases versus healthy controls. More precisely, increased small intestinal permeability was exclusively noted in non-IgAN GN patients, whereas IgAN patients exhibited a trend towards elevated small intestinal permeability. In total, 54% of patients with IgAN and 67% of non-IgAN GN patients had increased small intestinal permeability. Neither distal small intestinal and proximal colonic permeability nor colonic gut permeability indices (i.e., 2-5 h and 5-24 h S/E ratios) were significantly different between controls and any of the GN patient groups.

CONCLUSION

The present single center pilot study suggests that disturbed intestinal permeability is common in patients with glomerular diseases and is not specific for IgAN.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register DRKS00021533, Date: 24.04.2020.

Understanding disruption of the gut barrier during inflammation: Should we abandon traditional epithelial cell lines and switch to intestinal organoids?

Disruption of the intestinal epithelial barrier is a hallmark of mucosal inflammation. It increases exposure of the immune system to luminal microbes, triggering a perpetuating inflammatory response. For several decades, the inflammatory stimuli-induced breakdown of the human gut barrier was studied in vitro by using colon cancer derived epithelial cell lines. While providing a wealth of important data, these cell lines do not completely mimic the morphology and function of normal human intestinal epithelial cells (IEC) due to cancer-related chromosomal abnormalities and oncogenic mutations. The development of human intestinal organoids provided a physiologically-relevant experimental platform to study homeostatic regulation and disease-dependent dysfunctions of the intestinal epithelial barrier. There is need to align and integrate the emerging data obtained with intestinal organoids and classical studies that utilized colon cancer cell lines. This review discusses the utilization of human intestinal organoids to dissect the roles and mechanisms of gut barrier disruption during mucosal inflammation. We summarize available data generated with two major types of organoids derived from either intestinal crypts or induced pluripotent stem cells and compare them to the results of earlier studies with conventional cell lines. We identify research areas where the complementary use of colon cancer-derived cell lines and organoids advance our understanding of epithelial barrier dysfunctions in the inflamed gut and identify unique questions that could be addressed only by using the intestinal organoid platforms.

Organoids in gastrointestinal diseases: from experimental models to clinical translation

We are entering an era of medicine where increasingly sophisticated data will be obtained from patients to determine proper diagnosis, predict outcomes and direct therapies. We predict that the most valuable data will be produced by systems that are highly dynamic in both time and space. Three-dimensional (3D) organoids are poised to be such a highly valuable system for a variety of gastrointestinal (GI) diseases. In the lab, organoids have emerged as powerful systems to model molecular and cellular processes orchestrating natural and pathophysiological human tissue formation in remarkable detail. Preclinical studies have impressively demonstrated that these organs-in-a-dish can be used to model immunological, neoplastic, metabolic or infectious GI disorders by taking advantage of patient-derived material. Technological breakthroughs now allow to study cellular communication and molecular mechanisms of interorgan cross-talk in health and disease including communication along for example, the gut-brain axis or gut-liver axis. Despite considerable success in culturing classical 3D organoids from various parts of the GI tract, some challenges remain to develop these systems to best help patients. Novel platforms such as organ-on-a-chip, engineered biomimetic systems including engineered organoids, micromanufacturing, bioprinting and enhanced rigour and reproducibility will open improved avenues for tissue engineering, as well as regenerative and personalised medicine. This review will highlight some of the established methods and also some exciting novel perspectives on organoids in the fields of gastroenterology. At present, this field is poised to move forward and impact many currently intractable GI diseases in the form of novel diagnostics and therapeutics.

Schisandrin C improves leaky gut conditions in intestinal cell monolayer, organoid, and nematode models by increasing tight junction protein expression

BACKGROUND

Leaky gut symptoms and inflammatory bowel disease (IBD) are associated with damaged intestinal mucosa, intestinal permeability dysfunction by epithelial cell cytoskeleton contraction, disrupted intercellular tight junction (TJ) protein expression, and abnormal immune responses and are intractable diseases.

PURPOSE

We evaluated the effects of schisandrin C, a dibenzocyclooctadiene lignan from Schisandra chinensis, on intestinal inflammation and permeability dysfunction in gut mimetic systems: cultured intestinal cells, intestinal organoids, and a Caenorhabditis elegans model.

METHODS

Schisandrin C was selected from 9 lignan compounds from S. chinensis based on its anti-inflammatory effects in HT-29 human intestinal cells. IL-1β and Pseudomonas aeruginosa supernatants were used to disrupt intestinal barrier formation in vitro and in C. elegans, respectively. The effects of schisandrin C on transepithelial electrical resistance (TEER) and intestinal permeability were evaluated in intestinal cell monolayers, and its effect on intestinal permeability dysfunction was tested in mouse intestinal organoids and C. elegans by measuring fluorescein isothiocyanate (FITC)-dextran efflux. The effect of schisandrin C on TJ protein expression was investigated by western blotting and fluorescence microscopy. The signaling pathway underlying these effects was also elucidated.

RESULTS

Schisandrin C ameliorated intestinal permeability dysfunction in three IBD model systems and enhanced epithelial barrier formation via upregulation of ZO-1 and occludin in intestinal cell monolayers and intestinal organoids. In Caco-2 cells, schisandrin C restored IL-1β-mediated increases in MLCK and p-MLC expression, in turn blocking cytoskeletal contraction and subsequent intestinal permeabilization. Schisandrin C inhibited NF-ĸB and p38 MAPK signaling, which regulates MLCK expression and structural reorganization of the TJ complex in Caco-2 cells. Schisandrin C significantly improved abnormal FITC-dextran permeabilization in both intestinal organoids and C. elegans.

CONCLUSION

Schisandrin C significantly improves abnormal intestinal permeability and regulates the expression of TJ proteins, long MLCK, p-MLC, and inflammation-related proteins, which are closely related to leaky gut symptoms and IBD development. Therefore, schisandrin C is a candidate to treat leaky gut symptoms and IBDs.

Patient-derived organoids for therapy personalization in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders of the intestinal tract that have emerged as a growing problem in industrialized countries. Knowledge of IBD pathogenesis is still incomplete, and the most widely-accepted interpretation considers genetic factors, environmental stimuli, uncontrolled immune responses and altered intestinal microbiota composition as determinants of IBD, leading to dysfunction of the intestinal epithelial functions. In vitro models commonly used to study the intestinal barrier do not fully reflect the proper intestinal architecture. An important innovation is represented by organoids, 3D in vitro cell structures derived from stem cells that can self-organize into functional organ-specific structures. Organoids may be generated from induced pluripotent stem cells or adult intestinal stem cells of IBD patients and therefore retain their genetic and transcriptomic profile. These models are powerful pharmacological tools to better understand IBD pathogenesis, to study the mechanisms of action on the epithelial barrier of drugs already used in the treatment of IBD, and to evaluate novel target-directed molecules which could improve therapeutic strategies. The aim of this review is to illustrate the potential use of organoids for therapy personalization by focusing on the most significant advances in IBD research achieved through the use of adult stem cells-derived intestinal organoids.

Alisol B 23-Acetate Ameliorates Lipopolysaccharide-Induced Intestinal Barrier Dysfunction by Inhibiting TLR4-NOX1/ROS Signaling Pathway in Caco-2 Cells

Alisol B 23-Acetate (AB23A) is a naturally occurring triterpenoid, which can be indicated in the rhizome of medicinal and dietary plants from Alisma species. Previous studies have demonstrated that AB23A could inhibit intestinal permeability by regulating tight junction (TJ)-related proteins. Even so, the AB23A protective mechanism against intestinal barrier dysfunction remains poorly understood. This investigation seeks to evaluate the AB23A protective effects on intestinal barrier dysfunction and determine the mechanisms for restoring intestinal barrier dysfunction in LPS-stimulated Caco-2 monolayers. According to our findings, AB23A attenuated the inflammation by reducing pro-inflammatory cytokines production like IL-6, TNF-α, IL-1β, and prevented the paracellular permeability by inhibiting the disruption of TJ in LPS-induced Caco-2 monolayers after treated with LPS. AB23A also inhibited LPS-induced TLR4, NOX1 overexpression and subsequent ROS generation in Caco-2 monolayers. Transfected with NOX1-specific shRNA diminished the up-regulating AB23A effect on ZO-1 and occludin expression. Moreover, transfected with shRNA of TLR4 not only enhanced ZO-1 and occludin expression but attenuated NOX1 expression and ROS generation. Therefore, AB23A ameliorates LPS-induced intestinal barrier dysfunction by inhibiting TLR4-NOX1/ROS signaling pathway in Caco-2 monolayers, suggesting that AB23A may have positive impact on maintaining the intestinal barrier’s integrity.

Harnessing the Biology of Canine Intestinal Organoids to Heighten Understanding of Inflammatory Bowel Disease Pathogenesis and Accelerate Drug Discovery: A One Health Approach

In a recent issue of the Lancet, the prevalence of Inflammatory Bowel Disease (IBD) was estimated at 7 million worldwide. Overall, the burden of IBD is rising globally, with direct and indirect healthcare costs ranging between $14.6 and $31.6 billion in the U.S. alone in 2014. There is currently no cure for IBD, and up to 40% of patients do not respond to medical therapy. Although the exact determinants of the disease pathophysiology remain unknown, the prevailing hypothesis involves complex interplay among host genetics, the intestinal microenvironment (primarily bacteria and dietary constituents), and the mucosal immune system. Importantly, multiple chronic diseases leading to high morbidity and mortality in modern western societies, including type II diabetes, IBD and colorectal cancer, have epidemiologically been linked to the consumption of high-calorie, low-fiber, high monosaccharide, and high-fat diets (HFD). More specifically, data from our laboratory and others have shown that repeated consumption of HFD triggers dysbiotic changes of the gut microbiome concomitant with a state of chronic intestinal inflammation and increased intestinal permeability. However, progress in our understanding of the effect of dietary interventions on IBD pathogenesis has been hampered by a lack of relevant animal models. Additionally, current in vitro cell culture systems are unable to emulate the in vivo interplay between the gut microbiome and the intestinal epithelium in a realistic and translatable way. There remains, therefore, a critical need to develop translatable in vitro and in vivo models that faithfully recapitulate human gut-specific physiological functions to facilitate detailed mechanistic studies on the impact of dietary interventions on gut homeostasis. While the study of murine models has been pivotal in advancing genetic and cellular discoveries, these animal systems often lack key clinical signs and temporal pathological changes representative of IBD. Specifically, some limitations of the mouse model are associated with the use of genetic knockouts to induce immune deficiency and disease. This is vastly different from the natural course of IBD developing in immunologically competent hosts, as is the case in humans and dogs. Noteworthily, abundant literature suggests that canine and human IBD share common clinical and molecular features, such that preclinical studies in dogs with naturally occurring IBD present an opportunity to further our understanding on disease pathogenesis and streamline the development of new therapeutic strategies. Using a stepwise approach, in vitro mechanistic studies investigating the contribution of dietary interventions to chronic intestinal inflammation and "gut leakiness" could be performed in intestinal organoids and organoid derived monolayers. The biologic potential of organoids stems from the method's ability to harness hard-wired cellular programming such that the complexity of the disease background can be reflected more accurately. Likewise, the effect of therapeutic drug candidates could be evaluated in organoids prior to longitudinal studies in dog and human patients with IBD. In this review, we will discuss the value (and limitations) of intestinal organoids derived from a spontaneous animal disease model of IBD (i.e., the dog), and how it can heighten understanding of the interplay between dietary interventions, the gut microbiota and intestinal inflammation. We will also review how intestinal organoids could be used to streamline the preclinical development of therapeutic drug candidates for IBD patients and their best four-legged friends.

MODULATION OF INTESTINAL BARRIER FUNCTION BY GLUCOCORTICOIDS: LESSONS FROM PRECLINICAL MODELS

Glucocorticoids (GCs) are widely used drugs for their anti-inflammatory and immunosuppressant effects, but they are associated with multiple adverse effects. Despite their frequent oral administration, relatively little attention has been paid to the effects of GCs on intestinal barrier function. In this review, we present a summary of the published studies on this matter carried out in animal models and cultured cells. In cultured intestinal epithelial cells, GCs have variable effects in basal conditions and generally enhance barrier function in the presence of inflammatory cytokines such as tumor necrosis factor (TNF). In turn, in rodents and other animals, GCs have been shown to weaken barrier function, with increased permeability and lower production of IgA, which may account for some features observed in stress models. When given to animals with experimental colitis, barrier function may be debilitated or strengthened, despite a positive anti-inflammatory activity. In sepsis models, GCs have a barrier-enhancing effect. These effects are probably related to the inhibition of epithelial cell proliferation and wound healing, modulation of the microbiota and mucus production, and interference with the mucosal immune system. The available information on underlying mechanisms is described and discussed.

The Role of Glucocorticoids in Inflammatory Diseases

For more than 70 years, glucocorticoids (GCs) have been a powerful and affordable treatment option for inflammatory diseases. However, their benefits do not come without a cost, since GCs also cause side effects. Therefore, strong efforts are being made to improve their therapeutic index. In this review, we illustrate the mechanisms and target cells of GCs in the pathogenesis and treatment of some of the most frequent inflammatory disorders affecting the central nervous system, the gastrointestinal tract, the lung, and the joints, as well as graft-versus-host disease, which often develops after hematopoietic stem cell transplantation. In addition, an overview is provided of novel approaches aimed at improving GC therapy based on chemical modifications or GC delivery using nanoformulations. GCs remain a topic of highly active scientific research despite being one of the oldest class of drugs in medical use.

Ulcerative colitis: shedding light on emerging agents and strategies in preclinical and early clinical development

INTRODUCTION

Ulcerative colitis (UC) is an inflammatory disease of the large intestine. Progress in preclinical therapeutic target discovery and clinical trial design has resulted in the approval of new therapies. Nonetheless, remission rates remain below 30% thus underlining the need for novel, more effective therapies.

AREAS COVERED

This paper reviews current experimental techniques available for drug testing in intestinal inflammation and examines new therapies in clinical development for the treatment of UC. The authors searched the literature for 'ulcerative colitis' AND 'preclinical' OR 'drug target/drug name' (i.e. infliximab, vedolizumab, IL-12, IL-23, JAK, etc.). Studies that included preclinical in vivo or in vitro experiments are discussed. The clinicaltrial.gov site was searched for 'ulcerative colitis' AND 'Recruiting' OR 'Active, not recruiting' AND 'Interventional (Clinical Trial)' AND 'early phase 1' OR 'phase 1' OR 'phase 2' OR 'phase 3.'

EXPERT OPINION

Using in vivo, ex vivo, and/or in vitro models could increase the success rates of drugs moving to clinical trials, and hence increase the efficiency of this costly process. Selective JAK1 inhibitors, S1P modulators, and anti-p19 antibodies are the most promising options to improve treatment effectiveness. The development of drugs with gut-restricted exposure may provide increased efficacy and an improved safety.