Biopsy-derived Intestinal Epithelial Cell Cultures for Pathway-based Stratification of Patients With Inflammatory Bowel Disease

Dietary Carrageenan Amplifies the Inflammatory Profile, but not Permeability, of Intestinal Epithelial Cells from Patients With Crohn's Disease

BACKGROUND

The consumption of ultra-processed foods has increased significantly worldwide and is associated with the rise in inflammatory bowel diseases. However, any causative factors and their underlying mechanisms are yet to be identified. This study aimed to further elucidate whether different types of the dietary emulsifier carrageenan (CGN) can alter the permeability and inflammatory state of the intestinal epithelium.

METHODS

Caco-2/HT29-MTX cocultures (n = 4) were exposed to either κ-, ι-, or λ-CGN (100 µg mL-1) for 24 hours. Organoid-derived monolayers from patients with Crohn's Disease (CD) were exposed to κ-CGN (100 µg mL-1) for 48 hours (n = 10). In both models, an inflamed condition was established by adding a mix of inflammatory stimuli. Changes in permeability were measured by transepithelial electrical resistance (TEER). In the organoid-derived monolayers, cytokines were quantified in the apical and basolateral supernatant and gene expression was analyzed with RT-qPCR.

RESULTS

None of the CGN subtypes altered permeability of non-inflamed or inflamed Caco-2/HT29-MTX cocultures. In organoid-derived monolayers, κ-CGN did not affect TEER, but induced alterations in the gene expression of tight junctions and mucus proteins. Expression of TNF, IL8, and IL1B increased upon κ-CGN stimulation, both in inflamed and non-inflamed monolayers. Cytokine release in the supernatant was increased by κ-CGN for IL-6, IL-13, IL-4, IL-2, and IL-10.

CONCLUSIONS

Dietary CGN caused upregulation of inflammatory markers and affected cytokine release of intestinal epithelial cells from CD patients, while permeability remained unaltered. When inflammation was already present, this pro-inflammatory effect was more pronounced, suggesting a role for dietary CGN during active CD.

The Key Nutrients in the Mediterranean Diet and Their Effects in Inflammatory Bowel Disease: A Narrative Review

The gut microbiome, a collection of gut microorganisms, is crucial in the development and progression of inflammatory bowel diseases (IBD). Therefore, diet and dietary interventions are promising strategies to shape the gut microbiota for IBD management. Of all the diets studied in the IBD field, the Mediterranean diet has the least restrictive nature, promoting long-term adherence. The Mediterranean diet is rich in plants, with a high daily intake of fruits and vegetables (high in fiber, antioxidants, and vitamins), olive oil, whole grains, legumes, and nuts. It includes the moderate consumption of animal products such as oily fish (rich in mono- and polyunsaturated fatty acids), dairy products, and poultry, with a limited intake of red meat and processed foods. This diet is associated with a decreased risk of chronic diseases, including IBD. However, the mechanisms of specific nutrients behind these effects in the Mediterranean diet remain under investigation. Therefore, in this review, we aim to provide an overview of the nutrients that are abundant in the Mediterranean diet and their effects on IBD, with a main focus on preclinical evidence. While several nutrients like fructo-oligosaccharide, chitosan, plant-derived protein, polyphenols, omega-3 polyunsaturated fatty acids, and resveratrol have shown potential beneficial effects in preclinical models, clinical evidence is often limited. However, understanding the complex interactions between specific nutrients and IBD is essential to developing a tailored, multidisciplinary, and personalized approach for disease management; therefore, further research is required.

Blueberry extract attenuates DSS-induced inflammatory bowel disease in mice through inhibiting ER stress-mediated colonic apoptosis in mice

Inflammatory bowel disease (IBD) is a chronic, debilitating condition with limited therapeutic options. Dietary components like blueberries have emerged as potential modulators of inflammation and tissue repair in gastrointestinal diseases. This study investigated endoplasmic reticulum (ER) stress-mediated apoptosis mediated protective effects of blueberries in ameliorating dextran sulfate sodium (DSS)-induced IBD. Firstly, a total of 86 anthocyanin compounds were identified in blueberry extract by LC-MS spectroscopy, including 35 cyanidin, 9 delphinidin, 14 malvidin, 10 peonidin, and 9 petunidin. Then, the animal study showed that blueberry supplementation notably ameliorated DSS-induced IBD symptoms, as evidenced by improved histopathological scores and a reduced disease activity index (DAI) score. Additionally, blueberries attenuated ER stress by inhibiting the colonic PERK/eIF2α/ATF4/CHOP signaling pathway. Furthermore, blueberries inhibited the expression of the pro-apoptotic protein, caspase-3, and decreased colonic apoptosis, as evidenced by TUNEL assay results. However, it did not affect the expression of anti-apoptotic proteins, bcl-2 and bcl-xl. Finally, blueberries enhanced the intestinal barrier by upregulating ZO-1, claudin-1, occludin, and E-cadherin. In conclusion, blueberries demonstrate therapeutic potential against DSS-induced IBD-like symptoms in mice, possibly by regulating ER stress-mediated apoptosis pathways. These findings suggest that blueberries might be an effective dietary intervention for IBD management.

Endoplasmic reticulum stress in the pathogenesis of chemotherapy-induced mucositis: Physiological mechanisms and therapeutic implications

Chemotherapy is a common and effective treatment for cancer, but these drugs are also associated with significant side effects affecting patients' well-being. One such debilitating side effect is mucositis, characterized by inflammation, ulcerations, and altered physiological functions of the gastrointestinal (GI) tract's mucosal lining. Understanding the mechanisms of chemotherapy-induced intestinal mucositis (CIM) is crucial for developing effective preventive measures and supportive care. Chemotherapeutics not only target cancer cells but also rapidly dividing cells in the GI tract. These drugs disrupt endoplasmic reticulum (ER) homeostasis, leading to ER-stress and activation of the unfolded protein response (UPR) in various intestinal epithelial cell types. The UPR triggers signaling pathways that exacerbate tissue inflammation and damage, influence the differentiation and fate of intestinal epithelial cells, and compromise the integrity of the intestinal mucosal barrier. These factors contribute significantly to mucositis development and progression. In this review, we aim to give an in-depth overview of the role of ER-stress in mucositis and its impact on GI function. This will provide valuable insights into the underlying mechanisms and highlighting potential therapeutic interventions that could improve treatment-outcomes and the quality of life of cancer patients.

Serine metabolism is crucial for cGAS-STING signaling and viral defense control in the gut

Inflammatory bowel diseases are characterized by the chronic relapsing inflammation of the gastrointestinal tract. While the molecular causality between endoplasmic reticulum (ER) stress and intestinal inflammation is widely accepted, the metabolic consequences of chronic ER stress on the pathophysiology of IBD remain unclear. By using in vitro, in vivo models, and patient datasets, we identified a distinct polarization of the mitochondrial one-carbon metabolism and a fine-tuning of the amino acid uptake in intestinal epithelial cells tailored to support GSH and NADPH metabolism upon ER stress. This metabolic phenotype strongly correlates with IBD severity and therapy response. Mechanistically, we uncover that both chronic ER stress and serine limitation disrupt cGAS-STING signaling, impairing the epithelial response against viral and bacterial infection and fueling experimental enteritis. Consequently, the antioxidant treatment restores STING function and virus control. Collectively, our data highlight the importance of serine metabolism to allow proper cGAS-STING signaling and innate immune responses upon gut inflammation.

Oscillation of Autophagy Induction under Cellular Stress and What Lies behind It, a Systems Biology Study

One of the main inducers of autophagy-dependent self-cannibalism, called ULK1, is tightly regulated by the two sensor molecules of nutrient conditions and energy status, known as mTOR and AMPK kinases, respectively. Recently, we developed a freely available mathematical model to explore the oscillatory characteristic of the AMPK-mTOR-ULK1 regulatory triangle. Here, we introduce a systems biology analysis to explain in detail the dynamical features of the essential negative and double-negative feedback loops and also the periodic repeat of autophagy induction upon cellular stress. We propose an additional regulatory molecule in the autophagy control network that delays some of AMPK's effect on the system, making the model output more consistent with experimental results. Furthermore, a network analysis on AutophagyNet was carried out to identify which proteins could be the proposed regulatory components in the system. These regulatory proteins should satisfy the following rules: (1) they are induced by AMPK; (2) they promote ULK1; (3) they down-regulate mTOR upon cellular stress. We have found 16 such regulatory components that have been experimentally proven to satisfy at least two of the given rules. Identifying such critical regulators of autophagy induction could support anti-cancer- and ageing-related therapeutic efforts.

Prospective Validation of CD-62L (L-Selectin) as Marker of Durable Response to Infliximab Treatment in Patients With Inflammatory Bowel Disease: A 5-Year Clinical Follow-up

INTRODUCTION

The development of biomarkers to guide management of anti-tumor necrosis factor (TNF) agents in patients with inflammatory bowel disease (IBD) is an unmet need. We developed an in vitro blood assay to predict patient long-term outcome with the anti-TNFα agent infliximab (IFX).

METHODS

Patients with IBD were classified according to the shedding of an L-selectin (CD62L) from the surface of their granulocytes in whole blood. CD62L shedding was quantified by flow cytometry before and after drug administration. A clinical data collection from June 2012 to August 2017 with blinded IFX management was aimed at validating the long-term predictive value of this test.

RESULTS

Among 33 patients with IBD (17 Crohn's disease and 5 ulcerative colitis), 22 were predicted functional responders (PFR) and 11 were predicted as nonresponders (NR) according to the in vitro test. Five years after study initiation, 72% of PFR were still treated with IFX (vs 27% in the NR group; P < 0.05), with a median time spent under IFX of 45 vs 12 months (P = 0.019), respectively. Thirty-five medicosurgical events occurred with a median time to first event of 3 vs 30 months (P = 0.023), respectively. Our assay was the best independent predictor of staying long term on IFX (P = 0.056).

DISCUSSION

An assay-based in vitro test for functional blockade of TNFα (CD62L shedding) provides an excellent long-term (at 3-5 years) independent predictor of durable use of IFX in patients with IBD. Testing patients could personalize decision making to significantly reduce costs and risk of adverse events and complications.

Colonoids From Patients With Pediatric Inflammatory Bowel Disease Exhibit Decreased Growth Associated With Inflammation Severity and Durable Upregulation of Antigen Presentation Genes

BACKGROUND

Defining epithelial cell contributions to inflammatory bowel disease (IBD) is essential for the development of much needed therapies for barrier repair. Children with very early onset (VEO)-IBD have more extensive, severe, and refractory disease than older children and adults with IBD and, in some cases, have defective barrier function. We therefore evaluated functional and transcriptomic differences between pediatric IBD (VEO and older onset) and non-IBD epithelium using 3-dimensional, biopsy-derived organoids.

METHODS

We measured growth efficiency relative to histopathological and clinical parameters in patient enteroid (ileum) and colonoid (colon) lines. We performed RNA-sequencing on patient colonoids and subsequent flow cytometry after multiple passages to evaluate changes that persisted in culture.

RESULTS

Enteroids and colonoids from pediatric patients with IBD exhibited decreased growth associated with histological inflammation compared with non-IBD controls. We observed increased LYZ expression in colonoids from pediatric IBD patients, which has been reported previously in adult patients with IBD. We also observed upregulation of antigen presentation genes HLA-DRB1 and HLA-DRA, which persisted after prolonged passaging in patients with pediatric IBD.

CONCLUSIONS

We present the first functional evaluation of enteroids and colonoids from patients with VEO-IBD and older onset pediatric IBD, a subset of which exhibits poor growth. Enhanced, persistent epithelial antigen presentation gene expression in patient colonoids supports the notion that epithelial cell-intrinsic differences may contribute to IBD pathogenesis.

Regenerative Intestinal Stem Cells Induced by Acute and Chronic Injury: The Saving Grace of the Epithelium?

The intestinal epithelium is replenished every 3-4 days through an orderly process that maintains important secretory and absorptive functions while preserving a continuous mucosal barrier. Intestinal epithelial cells (IECs) derive from a stable population of intestinal stem cells (ISCs) that reside in the basal crypts. When intestinal injury reaches the crypts and damages IECs, a mechanism to replace them is needed. Recent research has highlighted the existence of distinct populations of acute and chronic damage-associated ISCs and their roles in maintaining homeostasis in several intestinal perturbation models. What remains unknown is how the damage-associated regenerative ISC population functions in the setting of chronic inflammation, as opposed to acute injury. What long-term consequences result from persistent inflammation and other cellular insults to the ISC niche? What particular "regenerative" cell types provide the most efficacious restorative properties? Which differentiated IECs maintain the ability to de-differentiate and restore the ISC niche? This review will cover the latest research on damage-associated regenerative ISCs and epigenetic factors that determine ISC fate, as well as provide opinions on future studies that need to be undertaken to understand the repercussions of the emergence of these cells, their contribution to relapses in inflammatory bowel disease, and their potential use in therapeutics for chronic intestinal diseases.

Intestinal Receptor of SARS-CoV-2 in Inflamed IBD Tissue Seems Downregulated by HNF4A in Ileum and Upregulated by Interferon Regulating Factors in Colon

BACKGROUND

Patients with inflammatory bowel disease [IBD] are considered immunosuppressed, but do not seem more vulnerable for COVID-19. Nevertheless, intestinal inflammation has shown to be an important risk factor for SARS-CoV-2 infection and prognosis. Therefore, we investigated the role of intestinal inflammation on the viral intestinal entry mechanisms, including ACE2, in IBD.

METHODS

We collected inflamed and uninflamed mucosal biopsies from Crohn's disease [CD] [n = 193] and ulcerative colitis [UC] [n = 158] patients, and from 51 matched non-IBD controls for RNA sequencing, differential gene expression, and co-expression analysis. Organoids from UC patients were subjected to an inflammatory mix and processed for RNA sequencing. Transmural ileal biopsies were processed for single-cell [sc] sequencing. Publicly available colonic sc-RNA sequencing data, and microarrays from tissue pre/post anti-tumour necrosis factor [TNF] therapy, were analysed.

RESULTS

In inflamed CD ileum, ACE2 was significantly decreased compared with control ileum [p = 4.6E-07], whereas colonic ACE2 was higher in inflamed colon of CD/UC compared with control [p = 8.3E-03; p = 1.9E-03]. Sc-RNA sequencing confirmed this ACE2 dysregulation and exclusive epithelial ACE2 expression. Network analyses highlighted HNF4A as key regulator of ileal ACE2, and pro-inflammatory cytokines and interferon regulating factors regulated colonic ACE2. Inflammatory stimuli upregulated ACE2 in UC organoids [p = 1.7E-02], but not in non-IBD controls [p = 9.1E-01]. Anti-TNF therapy restored colonic ACE2 regulation in responders.

CONCLUSIONS

Intestinal inflammation alters SARS-CoV-2 coreceptors in the intestine, with opposing dysregulations in ileum and colon. HNF4A, an IBD susceptibility gene, seems an important upstream regulator of ACE2 in ileum, whereas interferon signalling might dominate in colon.

Enteroids Derived From Inflammatory Bowel Disease Patients Display Dysregulated Endoplasmic Reticulum Stress Pathways, Leading to Differential Inflammatory Responses and Dendritic Cell Maturation

BACKGROUND AND AIMS

Endoplasmic reticulum [ER] stress in intestinal epithelial cells [IECs] contributes to the pathogenesis of inflammatory bowel disease [IBD]. We hypothesized that ER stress changes innate signalling in human IECs, augmenting toll-like receptor [TLR] responses and inducing pro-inflammatory changes in underlying dendritic cells [DCs].

METHODS

Caco-2 cells and primary human colon-derived enteroid monolayers were exposed to ATP [control stressor] or thapsigargin [Tg] [ER stress inducer], and were stimulated with the TLR5 agonist flagellin. Cytokine release was measured by an enzyme immunoassay. ER stress markers CHOP, GRP78 and XBP1s/u were measured via quantitative PCR and Western blot. Monocyte-derived DCs [moDCs] were cultured with the IEC supernatants and their activation state was measured. Responses from enteroids derived from IBD patients and healthy control participants were compared.

RESULTS

ER stress enhanced flagellin-induced IL-8 release from Caco-2 cells and enteroids. Moreover, conditioned media activated DCs to become pro-inflammatory, with increased expression of CD80, CD86, MHCII, IL-6, IL-15 and IL-12p70 and decreased expression of CD103 and IL-10. Flagellin-induced IL-8 production correlated with DC activation, suggesting a common stress pathway. Moreover, there were distinct differences in cytokine expression and basal ER stress between IBD and healthy subject-derived enteroid monolayers, suggesting a dysregulated ER stress pathway in IBD-derived enteroids.

CONCLUSIONS

Cellular stress enhances TLR5 responses in IECs, leading to increased DC activation, indicating a previously unknown mechanistic link between epithelial ER stress and immune activation in IBD. Furthermore, dysregulated ER stress may be propagated from the intestinal epithelial stem cell niche in IBD patients.

Decitabine attenuates dextran sodium sulfate‑induced ulcerative colitis through regulation of immune regulatory cells and intestinal barrier

To investigate the effect of decitabine on the regulation of intestinal barrier function in mice with inflammatory bowel disease, an experimental model of colitis was established via drinking water with dextran sulfate sodium (DSS). Hematoxylin and eosin staining was used to observe the pathological changes of the colon. Cytokine production was measured by an ELISA assay. Flow cytometry was used to measure the level of regulatory T cells. Immunofluorescence, immunohistochemistry and western blot analyses detected the protein expression and distribution in colon tissue. Following the administration of decitabine, the symptoms of intestinal inflammation in the mice were significantly relieved; the expression of IL-17 was decreased, and the levels of TGF-β and IL-10 were increased. In addition, the induction of forkhead box P3 (Foxp3) in naive T cells increased the proportion of CD4⁺ Foxp3⁺ T cells in CD4⁺ T cells. Furthermore, decitabine increased the levels of zonular occludens-1 and occludin, and inhibited the phosphorylation of ERK1/2, JNK and p38. In conclusion, the present study suggested that decitabine could alleviate DSS-induced impaired colon barrier and the weight loss, mucus and bloody stools in mice by releasing the inhibitory factor IL-10, reducing the pro-inflammatory factor IL-17, activating CD4⁺ Foxp3⁺ T cells and inhibiting the activation of the MAPK pathway.

Slit2/Robo1 Mitigates DSS-induced Ulcerative Colitis by Activating Autophagy in Intestinal Stem Cell

Ulcerative colitis (UC) is a recurrent intestinal inflammatory disease. Slit2, a secreted protein, interacts with its receptor Robo1 to regulate the differentiation of intestinal stem cells and participate in inflammation and tumor development. However, whether Slit2/Robo1involved in the pathogenesis of UC is not known. We investigated Slit2/Robo1-mediated UC using a dextran sodium sulfate (DSS)-induced model. Eight-week-old male Slit2-Tg (Slit2 transgene) mice, Robo1/2+/- (Robo1+/- Robo2+/-) mice, and their WT littermates were allocated into two groups: (I) control group (n=10), of mice fed a normal diet and tap water and (II) DSS group (n=10), of mice fed a normal diet and drinking water with 2% DSS for 7 days. Colon tissues were collected and analyzed by qPCR, immunohistochemistry, western blot, and immunofluorescence. Slit2-Tg DSS mice showed less body weight loss, less blood in the stool, and less viscous stool compared to those of WTSlit DSS mice. Robo1/2+/- DSS mice displayed a heavier degree of blood in the stool and a more apparent viscosity of the stool compared to those of WTRobo1/2 DSS mice. Slit2 overexpression maintained Lgr5+ stem cell proliferation in the crypt after DSS treatment, significantly increased the LC3II/I ratio, and slightly stimulated p62 expression in the crypt compared to those of DSS-induced WTSlit mice. Robo1/2 partial knockout reduced the number of Lgr5+ stem cells, decreased the LC3II/I ratio, and markedly increased p62 expression in the crypt compare to those of DSS-treated WTRobo1/2 mice. Our findings suggest that Slit2/Robo1 mediates DSS-induced UC probably by activating the autophagy of Lgr5+ stem cells.

New insights into the interplay between autophagy, gut microbiota and inflammatory responses in IBD

One of the most significant challenges of inflammatory bowel disease (IBD) research is to understand how alterations in the symbiotic relationship between the genetic composition of the host and the intestinal microbiota, under impact of specific environmental factors, lead to chronic intestinal inflammation. Genome-wide association studies, followed by functional studies, have identified a role for numerous autophagy genes in IBD, especially in Crohn disease. Studies using in vitro and in vivo models, in addition to human clinical studies have revealed that autophagy is pivotal for intestinal homeostasis maintenance, gut ecology regulation, appropriate intestinal immune responses and anti-microbial protection. This review describes the latest researches on the mechanisms by which dysfunctional autophagy leads to disrupted intestinal epithelial function, gut dysbiosis, defect in anti-microbial peptide secretion by Paneth cells, endoplasmic reticulum stress response and aberrant immune responses to pathogenic bacteria. A better understanding of the role of autophagy in IBD pathogenesis may provide better sub-classification of IBD phenotypes and novel approaches for disease management.Abbreviations: AIEC: adherent-invasive Escherichia coli; AMPK: AMP-activated protein kinase; ATF6: activating transcription factor 6; ATG: autophagy related; Atg16l1[ΔIEC] mice: mice with Atg16l1 depletion specifically in intestinal epithelial cells; Atg16l1[HM] mice: mice hypomorphic for Atg16l1 expression; BCL2: B cell leukemia/lymphoma 2; BECN1: beclin 1, autophagy related; CALCOCO2: calcium binding and coiled-coil domain 2; CASP: caspase; CD: Crohn disease; CGAS: cyclic GMP-AMP synthase; CHUK/IKKA: conserved helix-loop-helix ubiquitous kinase; CLDN2: claudin 2; DAPK1: death associated protein kinase 1; DCs: dendritic cells; DSS: dextran sulfate sodium; EIF2A: eukaryotic translation initiation factor 2A; EIF2AK: eukaryotic translation initiation factor 2 alpha kinase; ER: endoplasmic reticulum; ERBIN: Erbb2 interacting protein; ERN1/IRE1A: ER to nucleus signaling 1; FNBP1L: formin binding protein 1-like; FOXP3: forkhead box P3; GPR65: G-protein coupled receptor 65; GSK3B: glycogen synthase kinase 3 beta; IBD: inflammatory bowel disease; IECs: intestinal epithelial cells; IFN: interferon; IL: interleukin; IL10R: interleukin 10 receptor; IRGM: immunity related GTPase M; ISC: intestinal stem cell; LAMP1: lysosomal-associated membrane protein 1; LAP: LC3-associated phagocytosis; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; LPS: lipopolysaccharide; LRRK2: leucine-rich repeat kinase 2; MAPK: mitogen-activated protein kinase; MHC: major histocompatibility complex; MIF: macrophage migration inhibitory factor; MIR/miRNA: microRNA; MTMR3: myotubularin related protein 3; MTOR: mechanistic target of rapamycin kinase; MYD88: myeloid differentiation primary response gene 88; NLRP3: NLR family, pyrin domain containing 3; NOD2: nucleotide-binding oligomerization domain containing 2; NPC: Niemann-Pick disease type C; NPC1: NPC intracellular cholesterol transporter 1; OMVs: outer membrane vesicles; OPTN: optineurin; PI3K: phosphoinositide 3-kinase; PRR: pattern-recognition receptor; PTPN2: protein tyrosine phosphatase, non-receptor type 2; PTPN22: protein tyrosine phosphatase, non-receptor type 22 (lymphoid); PYCARD/ASC: PYD and CARD domain containing; RAB2A: RAB2A, member RAS oncogene family; RELA: v-rel reticuloendotheliosis viral oncogene homolog A (avian); RIPK2: receptor (TNFRSF)-interacting serine-threonine kinase 2; ROS: reactive oxygen species; SNPs: single nucleotide polymorphisms; SQSTM1: sequestosome 1; TAX1BP1: Tax1 binding protein 1; Th: T helper 1; TIRAP/TRIF: toll-interleukin 1 receptor (TIR) domain-containing adaptor protein; TLR: toll-like receptor; TMEM173/STING: transmembrane protein 173; TMEM59: transmembrane protein 59; TNF/TNFA: tumor necrosis factor; Treg: regulatory T; TREM1: triggering receptor expressed on myeloid cells 1; UC: ulcerative colitis; ULK1: unc-51 like autophagy activating kinase 1; WT: wild-type; XBP1: X-box binding protein 1; XIAP: X-linked inhibitor of apoptosis.

Butyrate Does Not Protect Against Inflammation-induced Loss of Epithelial Barrier Function and Cytokine Production in Primary Cell Monolayers From Patients With Ulcerative Colitis

BACKGROUND AND AIMS

In vitro studies using immortalised cancer cell lines showed that butyrate has an overall positive effect on epithelial barrier integrity, but the physiological relevance of cancer cell lines is limited. We developed epithelial monolayers from human tissue samples of patients with ulcerative colitis [UC] to assess the effect of butyrate on epithelial barrier function.

METHODS

A protocol to establish monolayers from primary epithelial cells of UC patients [n = 10] and non-UC controls [n = 10] was optimised. The monolayers were treated with 8 mM sodium butyrate ± tumour necrosis factor alpha [TNFα] and type II interferon [IFNγ] for 48 h. Changes in transepithelial electrical resistance were monitored. Barrier gene expression levels were measured. Inflammatory proteins in the supernatant of the cells were quantified with OLINK.

RESULTS

We demonstrated that primary monolayer cultures can be grown within 1 week of culture with robust resistance values and polarised tight junction expression. Butyrate treatment of the cultures increased resistance but was detrimental in combination with TNFα and IFNγ. The combined treatment further induced even higher IL8 mRNA and inflammatory protein secretion than for the inflammatory mediators alone. The observed effects were similar in cultures from patients and non-UC controls, suggesting that there were no patient-specific responses responsible for these findings.

CONCLUSIONS

We found that butyrate does not protect against inflammation-induced barrier dysfunction and even worsens its effects in primary epithelial monolayers of UC patients and controls. The basic mechanisms of butyrate should therefore be reconsidered in future studies, in particular in patients with active inflammation and pre-existing barrier defects as is known for UC.

Single cell analysis of Crohn's disease patient-derived small intestinal organoids reveals disease activity-dependent modification of stem cell properties

BACKGROUND

Intestinal stem cells (ISCs) play indispensable roles in the maintenance of homeostasis, and also in the regeneration of the damaged intestinal epithelia. However, whether the inflammatory environment of Crohn's disease (CD) affects properties of resident small intestinal stem cells remain uncertain.

METHODS

CD patient-derived small intestinal organoids were established from enteroscopic biopsy specimens taken from active lesions (aCD-SIO), or from mucosa under remission (rCD-SIO). Expression of ISC-marker genes in those organoids was examined by immunohistochemistry, and also by microfluid-based single-cell multiplex gene expression analysis. The ISC-specific function of organoid cells was evaluated using a single-cell organoid reformation assay.

RESULTS

ISC-marker genes, OLFM4 and SLC12A2, were expressed by an increased number of small intestinal epithelial cells in the active lesion of CD. aCD-SIOs, rCD-SIOs or those of non-IBD controls (NI-SIOs) were successfully established from 9 patients. Immunohistochemistry showed a comparable level of OLFM4 and SLC12A2 expression in all organoids. Single-cell gene expression data of 12 ISC-markers were acquired from a total of 1215 cells. t-distributed stochastic neighbor embedding analysis identified clusters of candidate ISCs, and also revealed a distinct expression pattern of SMOC2 and LGR5 in ISC-cluster classified cells derived from aCD-SIOs. Single-cell organoid reformation assays showed significantly higher reformation efficiency by the cells of the aCD-SIOs compared with that of cells from NI-SIOs.

CONCLUSIONS

aCD-SIOs harbor ISCs with modified marker expression profiles, and also with high organoid reformation ability. Results suggest modification of small intestinal stem cell properties by unidentified factors in the inflammatory environment of CD.