Validation and Optimization of an Ex Vivo Assay of Intestinal Mucosal Biopsies in Crohn's Disease: Reflects Inflammation and Drug Effects

A disease-associated gene desert directs macrophage inflammation through ETS2

Increasing rates of autoimmune and inflammatory disease present a burgeoning threat to human health1. This is compounded by the limited efficacy of available treatments1 and high failure rates during drug development2, highlighting an urgent need to better understand disease mechanisms. Here we show how functional genomics could address this challenge. By investigating an intergenic haplotype on chr21q22-which has been independently linked to inflammatory bowel disease, ankylosing spondylitis, primary sclerosing cholangitis and Takayasu's arteritis3-6-we identify that the causal gene, ETS2, is a central regulator of human inflammatory macrophages and delineate the shared disease mechanism that amplifies ETS2 expression. Genes regulated by ETS2 were prominently expressed in diseased tissues and more enriched for inflammatory bowel disease GWAS hits than most previously described pathways. Overexpressing ETS2 in resting macrophages reproduced the inflammatory state observed in chr21q22-associated diseases, with upregulation of multiple drug targets, including TNF and IL-23. Using a database of cellular signatures7, we identified drugs that might modulate this pathway and validated the potent anti-inflammatory activity of one class of small molecules in vitro and ex vivo. Together, this illustrates the power of functional genomics, applied directly in primary human cells, to identify immune-mediated disease mechanisms and potential therapeutic opportunities.

Hypo-osmotic stress induces the epithelial alarmin IL-33 in the colonic barrier of ulcerative colitis

Epithelial alarmins are gaining interest as therapeutic targets for chronic inflammation. The nuclear alarmin interleukin-33 (IL-33) is upregulated in the colonic mucosa of acute ulcerative colitis (UC) and may represent an early instigator of the inflammatory cascade. However, it is not clear what signals drive the expression of IL-33 in the colonic mucosa, nor is the exact role of IL-33 elucidated. We established an ex vivo model using endoscopic colonic biopsies from healthy controls and UC patients. Colonic biopsies exposed to hypo-osmotic medium induced a strong nuclear IL-33 expression in colonic crypts in both healthy controls and UC biopsies. Mucosal IL33 mRNA was also significantly increased following hypo-osmotic stress in healthy controls compared to non-stimulated biopsies (fold change 3.9, p-value < 0.02). We observed a modest induction of IL-33 in response to TGF-beta-1 stimulation, whereas responsiveness to inflammatory cytokines TNF and IFN-gamma was negligible. In conclusion our findings indicate that epithelial IL-33 is induced by hypo-osmotic stress, rather than prototypic proinflammatory cytokines in colonic ex vivo biopsies. This is a novel finding, linking a potent cytokine and alarmin of the innate immune system with cellular stress mechanisms and mucosal inflammation.

Association Between Ex Vivo Human Ulcerative Colitis Explant Protein Secretion Profiles and Disease Behaviour

BACKGROUND

The clinical course of ulcerative colitis (UC) is variable. There is an unmet clinical need for biomarkers of UC disease behaviour. We aimed to evaluate the association between ex vivo human UC explant conditioned media (explant-CM) secreted protein profiles and UC disease behaviour.

METHODS

UC patients undergoing endoscopy were prospectively recruited. Endoscopic biopsies were collected and explant-CM generated. Association between explant-CM protein secretion profiles and disease progression was evaluated. Disease progression was defined as the requirement for corticosteroid therapy, UC-related hospitalisation, UC-related surgery or the introduction of a new immunomodulatory agent. Association between explant-CM secreted protein profiles and anti-TNF failure status was also evaluated. p values < 0.05 were considered significant in analyses.

RESULTS

Twenty-four UC patients were included (age [median, range]) 55 [21-72] years; 50% female. Disease progression during follow-up occurred in twelve (50%) patients. Multivariate analysis, including endoscopic remission status, demonstrated reduced IL-2 secretion to be independently associated with UC disease progression, p = 0.01. In univariate analysis, anti-TNF failure status was associated with significantly increased IL-17A/F (p = 0.015) and IL-12 / IL-23p40 (p = 0.044) concentrations. In multivariate analysis, there was a trend towards an association between IL-17A/F and anti-TNF failure status (p = 0.069); FLT-1 was demonstrated to be independently associated with anti-TNF failure status (p = 0.016).

CONCLUSION

Reduced explant-CM secreted IL-2 is associated with UC disease progression. Increased secretion of IL-23 pathway-associated cytokines was observed in anti-TNF failure status consistent with previous reports. Ex vivo human UC explants, generated from endoscopic biopsies, have potential as precision medicine tools in inflammatory bowel disease.

Intracolonic Neuropeptide Y Y1 Receptor Inhibition Attenuates Intestinal Inflammation in Murine Colitis and Cytokine Release in IBD Biopsies

We have demonstrated that neuropeptide Y (NPY) can regulate pro-inflammatory signaling in the gut via cross-talk with the pro-inflammatory cytokine tumor necrosis factor (TNF). Here, we investigated if selective blocking of NPY receptors, NPY1R or NPY2R, using small molecule non-peptide antagonists (BIBP-3222 for NPY1R and BIIE-0246 for NPY2R) in the colon could attenuate intestinal inflammation by lowering TNF levels (BIBP - N-[(1R)]-4-[(Aminoiminomethyl)amino-1-[[[(4-hydroxyphenyl)methyl]amino]carbonyl]butyl-α-phenylbenzeneacetamide; BIIE - N-[(1S)-4-[(Aminoiminomethyl)amino]-1-[[[2-(3,5-dioxo-1,2-diphenyl-1,2,4-triazolidin-4-yl)ethyl]amino]carbonyl]butyl]-1-[2-[4-(6,11-dihydro-6-oxo-5H-dibenz[b,e]azepin-11-yl)-1-piperazinyl]-2-oxoethyl]-cyclopentaneacetamide). Colitis was induced using dextran sodium sulfate in drinking water for 7 days, or by adoptive T-cell transfer in RAG-/- mice. Colonic biopsies from healthy subjects (n = 10) and IBD patients (n = 34, UC = 20, CD = 14) were cultured ex vivo in presence or absence of NPY antagonists (100 µM, 20 h), and cytokine release into culture supernatants was measured by ELISA. Intracolonic administration of BIBP (but not BIIE) significantly reduced clinical, endoscopic, and histological scores, and serum TNF, interleukin (IL)-6, and IL-12p70 in DSS colitis; it also significantly attenuated histological damage and serum IL-6 in T-cell colitis (P < .05). Intracolonic administration of BIBP significantly reduced TNF and interferon (IFN)-γ release from UC biopsies, whereas BIIE downregulated only IFN-γ (P < .05). BIBP significantly reduced TNF and interferon (IFN)-γ release from UC biopsies, whereas BIIE downregulated only IFN-γ (P < .05). Our data suggest a promising therapeutic value for NPY1R inhibition in alleviating intestinal inflammation in UC, possibly as enemas to IBD patients.

A Gut-Ex-Vivo System to Study Gut Inflammation Associated to Inflammatory Bowel Disease (IBD)

Simple Summary

Inflammatory Bowel Disease (IBD) is a complex and multifactorial systemic disease of the gastrointestinal tract, characterized by chronic inflammation, thus resulting in tissue damage and, occasionally, in cancer development. Although the precise origin is still elusive, it is widely considered a disease of modern society, caused by a complex interaction between environment, genetic, immune system, and gut microflora (microbiota). Potentially affected by all the above-mentioned variables, which interplay are highly heterogeneous, the disease appears to be patient-specific. The latter phenomenon, together with the uncertain origin, also contributes to the lack of optimal clinical treatment of these patients. Therefore, the development of appropriate models is crucial to push the research forward and to define new valuable therapeutic approaches. Although tissue biopsies and/or animal models represent the best models to study IBD onset, progression, and clinical interventions, they are both affected by limitations such as invasiveness, cost- and time-consuming, and ethical issues such as animal suffering. Here we propose a novel approach based on the cultivation of mouse tissues (colon) in an ex vivo microfluidic device (Gut-Ex-Vivo System, GEVS) to study IBD. We demonstrate that explanted mouse tissues cultivated in our GEVS can be appropriately stimulated to recapitulate the onset of the disease, in a time- and cost- effective manner.

Abstract

Inflammatory bowel disease (IBD) is a complex, chronic, and dysregulated inflammatory condition which etiology is still largely unknown. Its prognosis and disease progression are highly variable and unpredictable. IBD comprises several heterogeneous inflammatory conditions ranging from Ulcerative Colitis (UC) to Crohn’s Disease (CD). Importantly, a definite, well-established, and effective clinical treatment for these pathologies is still lacking. The urgent need for treatment is further supported by the notion that patients affected by UC or CD are also at risk of developing cancer. Therefore, a deeper understanding of the molecular mechanisms at the basis of IBD development and progression is strictly required to design new and efficient therapeutic regimens. Although the development of animal models has undoubtedly facilitated the study of IBD, such in vivo approaches are often expensive and time-consuming. Here we propose an organ ex vivo culture (Gut-Ex-Vivo system, GEVS) based on colon from Balb/c mice cultivated in a dynamic condition, able to model the biochemical and morphological features of the mouse models exposed to DNBS (5–12 days), in 5 h. Indeed, upon DNBS exposure, we observed a dose-dependent: (i) up-regulation of the stress-related protein transglutaminase 2 (TG2); (ii) increased intestinal permeability associated with deregulated tight junction protein expression; (iii) increased expression of pro-inflammatory cytokines, such as TNFα, IFNγ, IL1β, IL6, IL17A, and IL15; (iv) down-regulation of the anti-inflammatory IL10; and (v) induction of Endoplasmic Reticulum stress (ER stress), all markers of IBD. Altogether, these data indicate that the proposed model can be efficiently used to study the pathogenesis of IBD, in a time- and cost-effective manner.

Myeloid-Derived Growth Factor Promotes Intestinal Glucagon-Like Peptide-1 Production in Male Mice With Type 2 Diabetes

Myeloid-derived growth factor (MYDGF), which is produced by bone marrow-derived cells, mediates cardiac repair following myocardial infarction by inhibiting cardiac myocyte apoptosis to subsequently reduce the infarct size. However, the function of MYDGF in the incretin system of diabetes is still unknown. Here, loss-of-function and gain-of-function experiments in mice revealed that MYDGF maintains glucose homeostasis by inducing glucagon-like peptide-1 (GLP-1) production and secretion and that it improves glucose tolerance and lipid metabolism. Treatment with recombinant MYDGF increased the secretion and production of GLP-1 in STC-1 cells in vitro. Mechanistically, the positive effects of MYDGF are potentially attributable to the activation of protein kinase A/glycogen synthase kinase 3β/β-catenin (PKA/GSK-3β/β-catenin) and mitogen-activated protein kinase (MAPK) kinases/extracellular regulated protein kinase (MEK/ERK) pathways. Based on these findings, MYDGF promotes the secretion and production of GLP-1 in intestinal L-cells and potentially represents a potential therapeutic medication target for type 2 diabetes.

Health-Promoting Properties of Proanthocyanidins for Intestinal Dysfunction

The intestinal barrier is constantly exposed to potentially harmful environmental factors, including food components and bacterial endotoxins. When intestinal barrier function and immune homeostasis are compromised (intestinal dysfunction), inflammatory conditions may develop and impact overall health. Evidence from experimental animal and cell culture studies suggests that exposure of intestinal mucosa to proanthocyanidin (PAC)-rich plant products, such as grape seeds, may contribute to maintaining the barrier function and to ameliorating the pathological inflammation present in diet-induced obesity and inflammatory bowel disease. In this review, we aim to update the current knowledge on the bioactivity of PACs in experimental models of intestinal dysfunction and in humans, and to provide insights into the underlying biochemical and molecular mechanisms.

Development of a Gut-On-A-Chip Model for High Throughput Disease Modeling and Drug Discovery

A common bottleneck in any drug development process is finding sufficiently accurate models that capture key aspects of disease development and progression. Conventional drug screening models often rely on simple 2D culture systems that fail to recapitulate the complexity of the organ situation. In this study, we show the application of a robust high throughput 3D gut-on-a-chip model for investigating hallmarks of inflammatory bowel disease (IBD). Using the OrganoPlate platform, we subjected enterocyte-like cells to an immune-relevant inflammatory trigger in order to recapitulate key events of IBD and to further investigate the suitability of this model for compound discovery and target validation activities. The induction of inflammatory conditions caused a loss of barrier function of the intestinal epithelium and its activation by increased cytokine production, two events observed in IBD physiopathology. More importantly, anti-inflammatory compound exposure prevented the loss of barrier function and the increased cytokine release. Furthermore, knockdown of key inflammatory regulators RELA and MYD88 through on-chip adenoviral shRNA transduction alleviated IBD phenotype by decreasing cytokine production. In summary, we demonstrate the routine use of a gut-on-a-chip platform for disease-specific aspects modeling. The approach can be used for larger scale disease modeling, target validation and drug discovery purposes.

Evaluation of Compound Activity in Primary Human Intestinal Organoids Using Gene Expression and Histology

Human intestinal organoids have enabled performance of functional epithelial studies and modeling of human diseases of the intestine. This unit describes 1) a method to isolate and culture crypts from human intestinal tissue, 2) use of combinatorial methods to expand stem cell-enriched spheroids and differentiate them into organoids composed of various intestinal epithelial cell types, and 3) methods to stimulate these organoids with and measure their responsiveness to external stimuli. To validate the differentiation, organoids can be stained to qualitatively evaluate the presence of colonic crypt morphology and specialized epithelial cell markers. These organoids are responsive to challenge with tumor necrosis factor α (TNFα), resulting in cytokine-induced apoptosis. TNFα-driven apoptosis can be blocked by a small-molecule inhibitor of Ire1α (4μ8C), an endoplasmic-reticulum stress sensor. This is one example of how the human intestinal organoid model can be a powerful tool to elucidate important biological pathways involved in human disease in intestinal epithelial cells. © 2019 by John Wiley & Sons, Inc.

Reproducing the human mucosal environment ex vivo: inflammatory bowel disease as a paradigm

PURPOSE OF REVIEW

The medical management of inflammatory bowel disease (IBD) remains problematic with a pressing need for innovation in drug development as well as delivery of personalized therapies. Both the disease's inherent pathophysiologic complexity and heterogeneity in its etiology conspire in making it difficult to accurately model for either the purposes of basic research or drug development. Multiple attempts at creating meaningful experimental models have fallen short of adequately recapitulating the disease and most do not capture any aspect of the cause or the effects of patient heterogeneity that underlays most of the difficulties faced by physicians and their patients. In vivo animal models, tissue culture systems, and more recent synthetic biology approaches are all too simplistically reductionist for the task. However, ex vivo culture platforms utilizing patient biopsies offer a system that more closely mimics end-stage disease processes that can be studied in detail and subjected to experimental manipulations.

RECENT FINDINGS

Recent studies describe further optimization of mucosal explant cultures in order to increase tissue viability and maintain a polarized epithelial layer. Current applications of the platform include studies of the interplay between the epithelial, immune and stromal compartment of the intestinal tissue, investigation of host-microbial interactions, preclinical evaluation of candidate drugs and uncovering mechanisms of action of established or emerging treatments for IBD.

SUMMARY

Patient explant-based assays offer an advanced biological system in IBD that recapitulates disease complexity and reflects the heterogeneity of the patient population. In its current stage of development, the system can be utilized for drug testing prior to the costlier and time-consuming evaluation by clinical trials. Further refinement of the technology and establishment of assay readouts that correlate with therapeutic outcomes will yield a powerful tool for personalized medicine approaches in which individual patient responses to available treatments are assessed a priori, thus reducing the need for trial and error within the clinical setting.

Increased immune cell infiltration in patient-derived tumor explants treated with Traniplatin: an original Pt(iv) pro-drug based on Cisplatin and Tranilast

Elevated intra-tumoral immune infiltrate is associated with an improved prognosis in cancer of distinct origins. Traniplatin (TPT) is a novel platinum(iv) pro-drug based on Cisplatin (CDDP) and the marketed drug Tranilast. When compared in vitro to Cisplatin, TPT showed increased cytotoxic activity against colon and lung cancer cells but decreased activity against immune cells. In addition, TPT efficiency was evaluated in tumor explants derived from colorectal cancer samples from patients subjected to intended curative surgery. TPT induced strong intra-tumoral cytotoxic activity yet was associated with an elevated presence of immune cell infiltrate, suggesting a reduced cytotoxic activity against immune cells in colorectal cancer.

Delivery of Mesenchymal Stem Cells from Gelatin-Alginate Hydrogels to Stomach Lumen for Treatment of Gastroparesis

Gastroparesis (GP) is associated with depletion of interstitial cells of Cajal (ICCs) and enteric neurons, which leads to pyloric dysfunction followed by severe nausea, vomiting and delayed gastric emptying. Regenerating these fundamental structures with mesenchymal stem cell (MSC) therapy would be helpful to restore gastric function in GP. MSCs have been successfully used in animal models of other gastrointestinal (GI) diseases, including colitis. However, no study has been performed with these cells on GP animals. In this study, we explored whether mouse MSCs can be delivered from a hydrogel scaffold to the luminal surfaces of mice stomach explants. Mouse MSCs were seeded atop alginate-gelatin, coated with poly-l-lysine. These cell-gel constructs were placed atop stomach explants facing the luminal side. MSCs grew uniformly all across the gel surface within 48 h. When placed atop the lumen of the stomach, MSCs migrated from the gels to the tissues, as confirmed by positive staining with vimentin and N-cadherin. Thus, the feasibility of transplanting a cell-gel construct to deliver stem cells in the stomach wall was successfully shown in a mice stomach explant model, thereby making a significant advance towards envisioning the transplantation of an entire tissue-engineered 'gastric patch' or 'microgels' with cells and growth factors.

Anti-NKG2D mAb: A New Treatment for Crohn's Disease?

Crohn’s disease (CD) and ulcerative colitis (UC) are immunologically-mediated, debilitating conditions resulting from destructive inflammation of the gastrointestinal tract. The pathogenesis of IBD is incompletely understood, but is considered to be the result of an abnormal immune response with a wide range of cell types and proteins involved. Natural Killer Group 2D (NKG2D) is an activating receptor constitutively expressed on human Natural Killer (NK), γδ T, mucosal-associated invariant T (MAIT), CD56⁺ T, and CD8⁺ T cells. Activation of NKG2D triggers cellular proliferation, cytokine production, and target cell killing. Research into the NKG2D mechanism of action has primarily been focused on cancer and viral infections where cytotoxicity evasion is a concern. In human inflammatory bowel disease (IBD) this system is less characterized, but the ligands have been shown to be highly expressed during intestinal inflammation and the following receptor activation may contribute to tissue degeneration. A recent phase II clinical trial showed that an antibody against NKG2D induced clinical remission of CD in some patients, suggesting NKG2D and its ligands to be of importance in the pathogenesis of CD. This review will describe the receptor and its ligands in intestinal tissues and the clinical potential of blocking NKG2D in Crohn’s disease.

An explant of heifer mammary gland to study the immune response of the organ

Continuous or primary epithelial cell lines have been extensively used to study the mammary gland immune response, but they are constituted by a single cell population. Our aim was to test whether an explant of heifer gland, where the tissue structure is maintained, might be a valid model to investigate the innate immune response to infection. The study was carried out on 2mm³-sections of heifer udders, in 2 consecutive trials, using LPS or LTA in the first trial and two different concentrations of Staphylococcus aureus (Staph. aureus) in the second. Treated and untreated sections were collected after 1h, 3h and 6h incubation; in the first trial, a final time-point at 18h was considered. The mRNA expression of TNFα, IL-1β, IL-6, IL-8 and LAP was analyzed by quantitative real-time PCR. Histological examination showed well-preserved morphology of the tissue, and apoptosis only showed a slight, not significant increase throughout the experiment. IL-1β and IL-6 were significantly up-regulated, in response to LPS or Staph. aureus, while TNF-α and IL-8 significantly increased only under LPS treatment. LAP expression showed a significant late increase when stimulated by LPS. The immunochemical staining of the sections demonstrated a higher number of T lymphocytes within the alveolar epithelium, in comparison with interstitial localization. Since the explants belonged to pubertal non-pregnant heifers, T cells may be regarded as resident cells, suggesting their participation in the regulation of mammary homeostasis. Therefore, applying our model would give new insights in the investigation of udder pathophysiology.