Paneth Cell Markers Research Articles

Metastasis of colon cancer requires Dickkopf-2 to generate cancer cells with Paneth cell properties.

Metastasis is the leading cause of cancer-related mortality. Paneth cells provide stem cell niche factors in homeostatic conditions, but the underlying mechanisms of cancer stem cell niche development are unclear. Here we report that Dickkopf-2 (DKK2) is essential for the generation of cancer cells with Paneth cell properties during colon cancer metastasis. Splenic injection of Dkk2 -knockout (KO) cancer organoids into C57BL/6 mice resulted in a significant reduction of liver metastases. Transcriptome analysis showed reduction of Paneth cell markers such as lysozymes in KO organoids. Single cell RNA sequencing analyses of murine metastasized colon cancer cells and patient samples identified the presence of lysozyme positive cells with Paneth cell properties including enhanced glycolysis. Further analyses of transcriptome and chromatin accessibility suggested Hepatocyte nuclear factor 4-alpha (HNF4A) as a downstream target of DKK2. Chromatin immunoprecipitation followed by sequencing analysis revealed that HNF4A binds to the promoter region of Sox9 , a well-known transcription factor for Paneth cell differentiation. In the liver metastatic foci, DKK2 knockout rescued HNF4A protein levels followed by reduction of lysozyme positive cancer cells. Taken together, DKK2-mediated reduction of HNF4A protein promotes the generation of lysozyme positive cancer cells with Paneth cell properties in the metastasized colon cancers.

Erbb3 regulation of secretory differentiation in the intestinal epithelium

Background: Previous work by our lab showed that intestinal-specific deletion of the ErbB3 receptor tyrosine kinase results in increased ileal Paneth cell numbers. These cells produce host defense peptides and support stem cells with growth factors. The mechanisms by which ErbB3 regulates Paneth cells are not well understood, but a candidate mediator is the polycomb repressor complex 1 component BMI1, which marks secretory progenitor cells. Furthermore, while there are no Paneth cells in the mouse colon, deep crypt secretory (DCS) cells are a distinct Reg4+ population that have some functional overlap with both Paneth and goblet cells; we will also test whether ErbB3 regulates DCS differentiation. Overall we are testing the hypothesis that ErbB3 regulates secretory cell numbers through BMI1. Methods: We bred Villin-Cre;ErbB3flox/flox mice (ErbB3ΔIE) to delete ErbB3 from the intestinal epithelium. Colonic sections from ErbB3ΔIE and ErbB3flox/flox littermates were subjected to RNAscope in situ hybridization for Reg4. RNA from mucosal scrapings (both ileum and colon) was assessed by qPCR for Reg4, Bmi1, and Lgr5. To test signaling mechanisms, we treated HT-29 cells with NRG-1β to activate ErbB3, +/- inhibitors to PI3K (LY294002), MEK/MAPK (U0126), or BMI1 (PTC-209). Colonoids and enteroids from ErbB3ΔIE and ErbB3flox/flox mice were used to confirm responses in a non-transformed system. Results: In ErbB3ΔIE mice, the colonic epithelium showed increased Reg4 levels and more Reg4+ cells compared to littermate controls, similar to our published data for the Paneth cell marker Lyz1 in ileum. BMI1 RNA and protein levels were also increased in both small and large intestinal mucosal scrapings from ErbB3ΔIE mice vs. littermates. ErbB3ΔIE colonoids had increased Reg4 versus control colonoids, and NRG-1β reduced levels in control but not ErbB3ΔIE cultures. Ileal enteroids showed a decrease in Lyz1 expression with Bmi1 inhibition and an increase in Bmi1 expression with PI3K and MAPK blockade. In HT-29 cells, NRG-1β treatment reduced Reg4 and Bmi1 expression. Conversely, Reg4 and Bmi1 were induced by PI3K inhibition with LY294002 (p<0.03) (p<0.0005) or MEK/MAPK inhibition with U0126 (p<0.05) (p<0.0001). Conclusions: NRG1-ErbB3 signaling restricts both ileal Paneth ( Lyz1+) and colonic DCS ( Reg4+) cell numbers. Furthermore, ErbB3 regulates Bmi1 expression through PI3K/Akt and MAPK signaling and BMI1 activity promotes secretory cell development. Since loss of DCS or Paneth cells has been shown to disrupt the intestinal stem cell niche and secretory cell markers are altered in several intestinal disease states, these results may point to potential future therapeutic avenues targeting this regulatory mechanism. NIH/NIDDK award R01DK095004. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 770: The innate immune system response to malignancy- under the radar

Abstract It has become clear that many cancers evade detection by, for example, silencing of immune checkpoints. Re-activation of the immune armamentarium by checkpoint inhibitors has improved survival in many types of cancer. However, we still are unable to gauge the response of the innate immune system (InImS) to incipient malignancy. The InImS is likely both a sentient early warning system and an immediately deployed cancer combatant. We describe a potential marker that quantifies the innate immune system response to multiple deadly tumors. Methods: We obtained a database of patients at high risk of colorectal neoplasia and prospectively noted those who contracted cancer on follow up. We contrasted the historic, premorbid biomarker response from the time of enrolment, primarily using the FERAD ratio. This was obtained by dividing the ferritin blood concentration by the denominator of fecal shedding of a Paneth cell marker, p87. We also compared the FERAD response to the absolute neutrophil:lymphocyte ratio (NLR), a known prognostic biomarker, and also the available, known PDL-1 response for each group of cancers. Results: We found that certain groups of cancers historically had very low FERAD ratios while others were high. Using FERAD ratios for lung, gastric, non-Hodgkin’s lymphoma, melanoma, thyroid, renal, and head and neck cancers, there is a significant inverse correlation between survival and FERAD (r=-0.8;p<0.025) which is similar to that of NLR (r=-0.7;p<0.035). For prostate cancer, breast, colorectal cancer (CRC), leukemia/MDS, there is a direct correlation between survival and FERAD (r=0.99;p<0.002). There is also an inverse relationship between NLR and PDL-1 response rates (r=-0.8;p<0.04). An observed mild positive trend for FERAD PDL-1 response rates may bode well for melanoma, lung, head and neck and renal cancers. Conclusions: Since p87 could be manipulated by dietary means to affect the FERAD ratio favorably, this could be incorporated into more effective chemotherapy regimens and result in better cancer treatment outcomes. Hepatocellular cancer (HCC) and CRC-liver metastasis appear to be immunological outliers. This will need an additional unique approach such as TIGIT intervention therapy (Zheng et al.. Immune checkpoint targeting TIGIT in HCC. Am J Transl Res. 2020). This may allow modulation of the immune response based on FERAD, NLR ratios, and other considerations of mutational burden and genetic mutations, in patients with selected cancers. Citation Format: Martin Tobi, Harvinder Talwar, Benita McVicker. The innate immune system response to malignancy- under the radar [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 770.

Aberrant miR-29 is a predictive feature of severe phenotypes in pediatric Crohn's disease.

Crohn's disease (CD) is a chronic inflammatory gut disorder. Molecular mechanisms underlying the clinical heterogeneity of CD remain poorly understood. MicroRNAs (miRNAs) are important regulators of gut physiology, and several have been implicated in the pathogenesis of adult CD. However, there is a dearth of large-scale miRNA studies for pediatric CD. We hypothesized that specific miRNAs uniquely mark pediatric CD. We performed small RNA-Seq of patient-matched colon and ileum biopsies from treatment-naive pediatric patients with CD (n = 169) and a control cohort (n = 108). Comprehensive miRNA analysis revealed 58 miRNAs altered in pediatric CD. Notably, multinomial logistic regression analysis revealed that index levels of ileal miR-29 are strongly predictive of severe inflammation and stricturing. Transcriptomic analyses of transgenic mice overexpressing miR-29 show a significant reduction of the tight junction protein gene Pmp22 and classic Paneth cell markers. The dramatic loss of Paneth cells was confirmed by histologic assays. Moreover, we found that pediatric patients with CD with elevated miR-29 exhibit significantly lower Paneth cell counts, increased inflammation scores, and reduced levels of PMP22. These findings strongly indicate that miR-29 upregulation is a distinguishing feature of pediatric CD, highly predictive of severe phenotypes, and associated with inflammation and Paneth cell loss.

A23 IMPAIRMENT OF INTESTINAL CRYPTAL STEM CELL CYCLE AND PANETH CELL PROLIFERATION BY CHRONIC STRESS

Abstract Background The small intestine’s epithelial barrier is essential for intestinal homeostasis and host defense. It consists of epithelial cells that are constantly renewed by crypt stem cells and their progeny, which have different functions in the gut. Chronic stress can impair the barrier by modulating the gut-brain axis, which involves the hypothalamic-pituitary-adrenal (HPA) axis, the vagus nerve, and the immune system. Chronic stress can also alter the gut microbiota, which can further influence the barrier and immune system. Aims The present study examines how chronic stress affects the crypt stem cell niche and function in the small intestine. Methods Restraint stress was applied to 6-8 weeks old mice in a plastic container for 1 hour daily for 7 days. The dark/light transition box test was used to evaluate the stress-induced behavior change. The Ussing chamber technique was used to assess the paracellular permeability of the small intestine. RNA was extracted from the mucosa and submucosa layers of the small intestine, after removing the muscle layer, and RNA sequencing analysis was performed. Immunofluorescence analysis was also performed on the small intestinal tissues to detect the expression of various markers. To assess the in vivo effect of cortisol, dexamethasone (a synthetic steroid activating same receptors as cortisol), or metyrapone (an 11β-hydroxylation blocker to inhibit cortisol production), was applied to the mice. Results We found that restraint stress induced anxiety-like behavior, increased small intestinal epithelial permeability, and reduced villus and crypt length in mice. RNA sequencing analysis revealed that restraint stress upregulated steroid-driven pathways and downregulated cell cycle and cell mitosis pathways in the small intestinal mucosa, suggesting increased cortisol production and decreased stem cell activity. Immunofluorescence analysis confirmed that restraint stress reduced the expression of stem cell marker Olfm-4 and proliferation markers Ki-67 and p-H3 in the small intestinal crypts. Dexamethasone, a synthetic glucocorticoid, mimicked the effects of restraint stress on crypt stem cell proliferation, while metyrapone, a steroid synthesis inhibitor, attenuated the effects of restraint stress on crypt stem cell proliferation. Restraint stress and dexamethasone also reduced Paneth cell RNA expression and marker in the small intestine. Conclusions Chronic stress induces anxiety, barrier dysfunction, and epithelial shortening. Chronic stress also alters crypt stem cell and Paneth cell expression. These findings show how chronic stress impacts intestinal epithelial renewal and differentiation, which may affect intestinal health and disease. Funding Agencies JSPS

Loss of Mptx2 alters bacteria composition and intestinal homeostasis potentially by impairing autophagy

A recent single-cell survey of the small-intestinal epithelium suggests that mucosal pentraxin 2 (Mptx2) is a new Paneth cell marker, but its function and involved mechanism in the Paneth cell are still unknown. Therefore, we create Mptx2 knockout (Mptx2−/−) mice to investigate its precise effects on intestinal homeostasis using models of lipopolysaccharide (LPS), methicillin-resistant Staphylococcus aureus (MRSA) peritoneal infection, and dextran sulfate sodium (DSS)–induced intestinal injury and inflammation. We here find that Mptx2 is selectively expressed in Paneth cells in the small intestines of mice. Mptx2−/− mice have increased susceptibility to intestinal inflammation and injured. Mptx2 deficiency reduces Paneth cell count and expression of antimicrobial factors, leading to altered intestinal bacteria composition. Loss of Mptx2 aggravates MRSA infection–induced damage in the intestine while decreasing autophagy in Paneth cells. Mptx2−/− mice are more vulnerable to LPS-induced intestinal possibly due to inhibition of the autophagy/endoplasmic reticulum (ER) stress pathway. Mptx2−/− mice are susceptible to DSS-induced colitis that could be ameliorated by treatment with gentamicin or vancomycin antibiotics. In conclusion, Mptx2 is essential to maintain intestinal homeostasis potentially via regulation of autophagy in Paneth cells.

Paneth cell proteins DEFA6 and GUCA2A as tissue markers in necrotizing enterocolitis

Previous studies suggest that Paneth cells are involved in NEC development. Defensin alpha 6 (DEFA6) and guanylate cyclase activator 2A (GUCA2A) are selective protein markers of Paneth cells. The objective was to explore DEFA6 and GUCA2A expression in intestinal tissue samples from newborn infants with and without NEC. Tissue samples from histologically intact intestine were analyzed from 70 infants: 43 underwent bowel resection due to NEC and 27 controls were operated due to conditions such as intestinal atresia, dysmotility, aganglionosis, pseudo-obstruction or volvulus. Each tissue sample was immunohistochemically stained for DEFA6 and GUCA2A. Semi-automated digital image analysis was performed to determine protein expression. Clinical data and protein expressions were compared between the groups. DEFA6 expression was lower in the NEC group (p = 0.006). Low DEFA6 correlated with risk of developing NEC in a logistic regression analysis, independently of gestational age and birth weight (OR 0.843 [CI 0.732–0.971]; p = 0.018). GUCA2A expression did not differ between the two groups.Conclusion: Lower expression of DEFA6 together with intact GUCA2A expression indicates that NEC patients have well-defined Paneth cells but diminished defensin activity. Our results suggest that DEFA6 could be used as a biomarker for NEC.What is Known:• Previous studies of defensin activity in NEC have been inconsistent, showing that defensin levels may be increased or diminished in NEC. GUCA2A has to our knowledge never been studied in NEC.What is New:• This study benchmarks two specific Paneth cell markers (DEFA6 and GUCA2A) and their activity in individuals with and without NEC.• The key finding is that the NEC group had a lower DEFA6 expression compared to the Controls, while the expression of GUCA2A did not differ between the groups.

Effects of microencapsulated blend of organic acids and botanicals on growth performance, intestinal barrier function, inflammatory cytokines, and endocannabinoid system gene expression in broiler chickens

With restricted usage of growth-promoting antibiotics, identifying alternative feed additives that both improve intestinal barrier function and reduce inflammation is the center to improve chickens' health. This study examined the effects of a microencapsulated feed additive containing citric acid, sorbic acids, thymol, and vanillin on intestinal barrier function and inflammation status. A total of 240 birds were assigned to either a commercial control diet or control diet supplemented with 500 g/MT of the microencapsulated additive product. Birds were raised by feeding a 2-phase diet (starter, d 1 to d 21; and grower, d 15 to d 42). Growth performance was recorded weekly. At d 21 and d 42, total gastrointestinal tract permeability was evaluated by FITC-dextran (FD4) oral gavage. Jejunum-specific barrier functions were evaluated by Ussing chamber. Intestinal gene expression of selected epithelial cell markers, tight junction (TJ) proteins, inflammatory cytokines, and endocannabinoid system (ECS) markers were determined by RT-PCR. Statistical analysis was performed using Student t test. Results showed significant improvement of feed efficiency in the birds supplemented with the blend of organic acids and botanicals. At d 21, both oral and jejunal FD4 permeability were lower in the supplemented group. Jejunal transepithelial resistance was higher in the supplemented birds. At d 21, expression of TJs mRNA (CLDN1 and ZO2) was both upregulated in the jejunum and ileum of supplemented birds, while CLDN2 was downregulated in cecum. Proliferating cell marker SOX9 was higher expressed in jejunum and ceca. Goblet cell marker (MUC2) was upregulated, while Paneth cell marker (LYZ) was downregulated in the ileum. Proinflammatory cytokine expressions of IL1B, TNFA, and IFNG were downregulated in jejunum, while anti-inflammatory IL10 expression was higher in jejunum, ileum, cecum, and cecal tonsil. The ECS markers expressions were upregulated in most intestinal regions. Together, these results demonstrated that the blend of organic acids and botanical supplementation reduced inflammation, improved the TJs expression and intestinal barrier function, and thus improved chicken feed efficiency. The activated ECS may play a role in reducing intestinal tissue inflammation.

PSIX-20 Nrf2 Pathway Mediates Resistance to Weaning Stress-Induced Intestinal Injury in Piglets of Different Breeds

Abstract The intestine is the central organ of early weaning stress in piglets; however, the response of intestinal stem cells (ISCs) that drive epithelial renewal between the different breeds of piglets is not yet known. Therefore, this investigation was to explore the sensitivity of ISCs to early weaning stress. Taoyuan Black and Duroc piglets were slaughtered at 21 days of age (on the day of weaning) and 24 days of age (3 days after weaning) with 10 pigs, respectively. And the results showed that Taoyuan Black pigs are more tolerant to early weaning stress, while the mucosal mass of jejunum was significantly decreased in 24-day-old Duroc piglets compared with the 21-day-old Duroc piglets (P < 0.05). The weaning stress damaged the jejunal structure, decreased the expression of tight junction related proteins ZO-1, Occludin, and Claudin-1, and increased intestinal permeability in Duroc piglets (P < 0.05). The ex vivo intestinal organoids (IOs) derived from the jejunal crypt of Duroc piglets after weaning exhibited lower expansion efficiency (P < 0.05). Furthermore, the levels of proliferating cell marker PCNA, terminally differentiated cell marker KRT20, absorptive cell marker Villin, goblet cell marker MUC2, and Paneth cell marker lysozyme were significantly reduced in the jejunum, crypt, and jejunal organoids of 24-day-old Duroc (P < 0.05). ROS levels in the jejunum of Duroc piglets were increased along with the inhibition of the Nrf2 pathway compared with 21-day-old Duroc piglets (P < 0.05). Collectively, the Taoyuan Black pigs had stronger tolerance to weaning stress; however early weaning suppressed the Nrf2 pathway, decreased proliferation and differentiation activity of ISCs, and disrupted intestinal homeostasis in Duroc piglets.

P-112 Oleic acid promotes the malignant transformation of Kras-mutant colonic organoids via the expansion of tumorigenic stem cells and abnormal Paneth cells through upregulation of NFATc family

Although the five-year survival rate of colorectal cancer (CRC) is significantly high with localized stage (90%), only 38% of the patients are diagnosed at this stage. Therefore, finding high risk factors of CRC could prevent the disease at the early stage. Obesity and high-fat diet consumption are risk factors of CRC. In detail, oleic acids (OA) were found to accumulate in the adipose tissues of obese patients as well as being the most common long chain fatty acid in dietary lipid. The role of OA in colorectal cancer development is still controversary. On the other hand, organoids, which can be derived from adult tissue stem cells, are the miniatures of organs. Recent works suggest organoids are useful tools to dissect mechanisms involved in cancer development. The current work aims to utilize crypt stem cell-derived organoids to dissect how obesity can contribute to CRC development. Organoids were derived from Lgr5 + -EGFP mice (normal colon control), Lgr5 + -EGFP-creER; LSL-KrasG12D mice (colonic epithelium harbored KrasG12D mutation) and AOM/DSS-induced CRC mice (cancerous colon control). For in-vitro, the impact of OA on the malignant transformation of Kras-mutant colonic organoids was assessed by MTT proliferation assay, 2D transwell migration and invasion assay, irinotecan-resistant test and colony formation assay. The tumor formation in-vivo was induced by subcutaneous engrafting of OA-treated organoids on NOD/SCID mice. RNAseq was done to screen some differential expressed genes when treating OA. The existence of stem cell and abnormal Paneth cell population was demonstrated by immunostaining, flow cytometry and ELISA. OA enhanced the malignant of Kras-mutant colonic organoids through increasing proliferation, migration, invasion, drug resistance and colony formation. Besides, mice which were engrafted with OA-trained Lgr5-Kras organoids possessed larger tumors. The colonic stem cell population which were represented by positive Lgr5-GFP + cells were upregulated in OA-treated group. Interestingly, there is an existence of abnormal Lyz + /CD24 + Paneth cells in OA-treated Kras-mutant organoids. This suggested that OA may promote abnormal differentiation of colonic progenitor cells. Indeed, treatment of OA upregulated ATOH1 and GFI1, which contributed to select between goblet/Paneth and enteroendocrine cell fates. Besides, NFAT family, among which NFATc3 expressed the most, significantly increased in OA-treated organoids. The upregulation of NFATc was induced by inhibition of proteasomal degradation resulting from low expression of the complex RNF123, USP18 and TRIM30A. In addition, inhibition of the nuclear translocalization of NFATc family by VIVIT demonstrated the decline of stemness markers as well as Paneth cell markers. Finally, we showed the role of NFATc, especially NFATc3, in promoting the malignancy of OA-treated Kras-mutant organoids. Our findings suggested the impact of oleic acid on promoting the malignant transformation of Kras-mutant colonic organoids through NFATc-relating pathway. The expansion of tumorigenic stem cells via induction of abnormal Paneth cell, may contribute to the potential of cancer-toward metaplasia in Kras-mutant organoids when exposing to high level of oleic acid. Oleic acid is an unfavorable factor of colorectal cancer. The frequent usage of OA, which may benefit to cardiovascular diseases, may lead to the increased risk of CRC in latent sensitive Kras-mutant individuals.

Dietary Indole‐3‐Carbinol Supplementation Restores Epithelial Abnormalities in SAMP1/YitFc Mouse Model of Ileitis

SAMP1/YitFC (SAMP) mice exhibit spontaneous ileitis as they age with morphological and functional epithelial abnormalities mimicking human Crohn’s disease, a chronic disease characterized by ileal inflammation. Indole‐3‐carbinole (I3C), found in broccoli and Brussel sprouts, plays a crucial role in the anti‐inflammatory processes by activating the aryl hydrocarbon receptor (AhR), a transcription factor vital for epithelial and immune cell functions. The impact of I3C diet on disease progression and epithelial integrity in SAMP model of ileitis is not known.Methods6‐week‐old male and female (n=8 per group) SAMP and control AKR/J mice (Jackson) were fed for 14 weeks either a standard chow diet or a purified diet supplemented with 200 ppm with indole‐3‐carbinole (+I3C diet), or purified diet depleted of AhR ligands (‐I3C diet). Ileum samples were collected for qPCR and histological analyses. Statistical analysis was performed by Tukey’s multiple comparison test for all three diets. To detect changes between +I3C vs. ‐I3C, delta values (Δ +/‐I3C = SAMP‐AKR) were analyzed by unpaired T‐test.ResultsAs expected, H&E staining for the ileum of SAMP mice fed chow diet, showed thickening of the muscle layer, neutrophil infiltration, and epithelial tufting vs. AKR mice. Severity of inflammation in SAMP mice, as assessed by fecal calprotectin ELISA, mRNA expression of cytokines, and histological analysis was not significantly impacted by dietary depletion or supplementation of I3C. With respect to epithelial abnormalities, Periodic Acid Schiff staining showed increased number of goblet cells per villi (~47‐75%) in SAMP mice on all three diets. While mRNA levels of the major goblet cell secretory proteins, mucin2 (Muc2) and intestinal trefoil factor (ITF), were dramatically decreased in SAMP mice vs. AKR, supplementation of I3C attenuated this decrease in Muc2 and ITF by ~35% and 51% (p<.001), respectively, indicating defective synthesis or secretion. Similarly, I3C diet significantly (p<.01) attenuated the decrease in Paneth cell markers lysozyme C‐1 (LYZ1) alpha defensin 5 (Def5α) and regenerating islet‐derived protein 3 alpha (Reg3α) in SAMP mice by ~65%, 60%, and 24%, respectively. A decrease in fibroblast growth factor 15 (FGF15) and the epithelial ion transporters serotonin transporter (SERT) and organic solute transporter (OST) were observed in ileal mucosa of SAMP mice vs. AKR, and the supplementation of I3C mitigated these decreases by 30‐58% (p<.01). There were no significant changes in the expression of tryptophan hydroxylase 1 (tph‐1), C‐X‐C motif chemokine ligand 2 (CXCL2), or AhR by I3C diet in SAMP mice. In summary, I3C supplementation significantly attenuated the goblet cell, Paneth cell, and epithelial‐specific abnormalities seen in SAMP mice. These data imply that dietary supplementation of AhR ligands may be a viable therapeutic strategy for Crohn’s patients to restore epithelial integrity.

The ErbB3 Receptor Restricts Bmi1 to Regulate Paneth Cells

ErbB3 is a RTK family member known to regulate proliferation and growth in the intestinal epithelium. Previous work by our lab determined that targeted Erbb3 deletion from the intestinal epithelium resulted in precocious Paneth cell development and an expanded population in mice. This was associated with increased expression of intestinal stem cell (ISC) markers. Conversely, ileal enteroids treated with the ErbB3 ligand neuregulin (NRG)‐1β had significantly reduced expression of ISC markers, including Lgr5 and Bmi1. These data suggest that ErbB3 restricts secretory cell differentiation and stemness in the intestinal crypt. However, the underlying mechanisms are largely unknown. BMI1 is a proto‐oncogene and member of the PRC complex. Bmi1+ intestinal epithelial cells represent a slow‐cycling ISC population that can regenerate the epithelium following injury and loss of Lgr5+ ISCs. Recent evidence determined that Bmi1+ ISCs are enriched in enteroendocrine markers and can give rise to goblet cells, suggesting BMI1 may be critical for differentiation of secretory lineages. We hypothesized that ErbB3 restricts secretory cell differentiation through regulation of BMI1.AimsTo define ErbB3‐dependent regulation of Bmi1 and determine if ErbB3 restriction of Paneth cell development and differentiation is through suppression of Bmi1.MethodsMucosal scrapings were collected from Vil‐Cre;Erbb3flox/flox mice and Erbb3flox/flox littermate controls for protein and gene expression analysis. Ileal enteroids and HT‐29 colorectal adenocarcinoma cells were treated with vehicle DMSO, the PI3K inhibitor LY294002 (10 μM), the MEK inhibitor U0126 (5 μM), the BMI1 inhibitor PTC‐209 (1 μM), and/or recombinant NRG‐1β (10 ng/mL). Enteroids and cell monolayers were harvested and prepared for gene expression analysis. RT‐qPCR for Bmi1 and Lyz1 was performed relative to Hprt as a loading control. Statistical analysis by one‐way ANOVA was conducted using Prism 9.ResultsConsistent with previous data, BMI1 protein and gene expression were significantly increased in small and large intestinal mucosal scrapings from Vil‐Cre;Erbb3flox/flox mice versus littermate controls. To determine if Bmi1 expression is sensitive to PI3K/Akt or MAPK signaling downstream of ErbB3, HT‐29 cells were treated with inhibitors followed by NRG‐1β after 1 hour, then harvested 24 hours later. PI3K and MAPK inhibition significantly increased Bmi1 expression. NRG‐1β treatment was able to overcome MAPK inhibition to reduce BMI1 expression. Similarly, in ileal enteroids, PI3K and MAPK blockade increased Bmi1 expression and NRG‐1β treatment reversed this effect. To determine whether BMI1 regulates expression of the Paneth cell marker LYZ1, HT‐29 cells were treated with the BMI1 inhibitor PTC‐209. BMI1 inhibition decreased LYZ1 expression.ConclusionsOur data demonstrate that ErbB3 regulates Bmi1 expression through PI3K/Akt and MAPK signaling in both human and mouse intestinal cells. Furthermore, BMI1 activity promotes LYZ1 expression. Together, these results support our hypothesis that ErbB3 regulates secretory cell differentiation through BMI1 in the intestinal epithelium.

A potent HNF4α agonist reveals that HNF4α controls genes important in inflammatory bowel disease and Paneth cells

HNF4α has been implicated in IBD through a number of genome-wide association studies. Recently, we developed potent HNF4α agonists, including N-trans caffeoyltyramine (NCT). NCT was identified by structural similarity to previously the previously identified but weak HNF4α agonists alverine and benfluorex. Here, we administered NCT to mice fed a high fat diet, with the goal of studying the role of HNF4α in obesity-related diseases. Intestines from NCT-treated mice were examined by RNA-seq to determine the role of HNF4α in that organ. Surprisingly, the major classes of genes altered by HNF4α were involved in IBD and Paneth cell biology. Multiple genes downregulated in IBD were induced by NCT. Paneth cells identified by lysozyme expression were reduced in high fat fed mice. NCT reversed the effect of high fat diet on Paneth cells, with multiple markers being induced, including a number of defensins, which are critical for Paneth cell function and intestinal barrier integrity. NCT upregulated genes that play important role in IBD and that are downregulated in that disease. It reversed the loss of Paneth cell markers that occurred in high fat diet fed mice. These data suggest that HNF4α could be a therapeutic target for IBD and that the agonists that we have identified could be candidate therapeutics.

A17 TRP53 REGULATES ESLF-RENEWAL AND CELL DIFFERENTIATION IN KRT15+ INTESTINAL STEM CELLS

Abstract Background Different pools of stem cells assure the intestinal epithelium homeostasis and regeneration. We recently reported that Krt15+ intestinal cells harbor self-renewal, multipotent and regenerative capacities, characteristics consistent with a stem cell population. p53 has been associated with the development of various types of cancer, and recent studies suggested it also regulates adult stem cell behavior in some tissues. However, its role in the maintenance of intestinal stem cells has not been explicitly covered. Therefore, we hypothesize that Trp53 loss specifically in Krt15+ intestinal stem cells will perturb the epithelial homeostasis and differentiation. Aims Identify the role of Trp53 in the regulation of intestinal stem cell and intestinal homeostasis Methods To induce Trp53 loss specifically in Krt15+ cells, we generated Krt15 CrePR1;Trp53fl/fl ( Krt15△Trp53) mice and induced Cre recombination by injecting RU486 (PR agonist). Mice were euthanized after Cre recombination at different time points. Organoid cultures were established from control and experimental mice. Results Two-month post Cre recombination, we observed no major morphological changes in the intestinal epithelium. However, we observed that crypts isolated from Krt15△Trp53 mice died rapidly and had difficulties forming organoids. When hyperactivating the Wnt/beta-catenin pathway through CHIR treatment, we observed that budding capacity was maintained in experimental organoids while control organoids formed mainly cysts as expected. We also observed an increased in Paneth cell-specific genes, suggesting an enrichment in Paneth cells. Interestingly, the expression of EpHB2 receptor and its target genes was decreased in organoids derived from Krt15△Trp53 mice. Ephrin signaling plays a crucial role in intestinal homeostasis by regulating cell position and migration, and previous studies suggest that ephrin receptors are a target of p53. Indeed, twelve-month post Cre recombination, altered architecture of crypt and villi was noted in the small intestinal epithelium of Krt15△Trp53 mice. Differentiation towards secretory cell types, specifically Paneth, goblet, and tuft cells, are significantly increased in Krt15△Trp53 mice. Interestingly, we also observed crypt cells expressing both goblet and Paneth cell markers suggesting dysfunction in the cell fate decision. Finally, decreased Notch pathway activation was also observed supporting that Trp53 loss, specifically in Krt15+ cells, leads to a dysregulation of secretory cell fate. Conclusions Loss of Trp53 specifically in Krt15+ cells affects the small intestinal homeostasis and secretory cell differentiation. Decreased Notch and ephrin signaling support the possible role of Trp53 in cell fate decision and self-renewal. Funding Agencies None

Single-Cell Analysis Reveals Unexpected Cellular Changes and Transposon Expression Signatures in the Colonic Epithelium of Treatment-Naïve Adult Crohn's Disease Patients.

Background & AimsThe intestinal barrier comprises a monolayer of specialized intestinal epithelial cells (IECs) that are critical in maintaining mucosal homeostasis. Dysfunction within various IEC fractions can alter intestinal permeability in a genetically susceptible host, resulting in a chronic and debilitating condition known as Crohn’s disease (CD). Defining the molecular changes in each IEC type in CD will contribute to an improved understanding of the pathogenic processes and the identification of cell type–specific therapeutic targets. We performed, at single-cell resolution, a direct comparison of the colonic epithelial cellular and molecular landscape between treatment-naïve adult CD and non–inflammatory bowel disease control patients.MethodsColonic epithelial-enriched, single-cell sequencing from treatment-naïve adult CD and non–inflammatory bowel disease patients was investigated to identify disease-induced differences in IEC types.ResultsOur analysis showed that in CD patients there is a significant skew in the colonic epithelial cellular distribution away from canonical LGR5+ stem cells, located at the crypt bottom, and toward one specific subtype of mature colonocytes, located at the crypt top. Further analysis showed unique changes to gene expression programs in every major cell type, including a previously undescribed suppression in CD of most enteroendocrine driver genes as well as L-cell markers including GCG. We also dissect an incompletely understood SPIB+ cell cluster, revealing at least 4 subclusters that likely represent different stages of a maturational trajectory. One of these SPIB+ subclusters expresses crypt-top colonocyte markers and is up-regulated significantly in CD, whereas another subcluster strongly expresses and stains positive for lysozyme (albeit no other canonical Paneth cell marker), which surprisingly is greatly reduced in expression in CD. In addition, we also discovered transposable element markers of colonic epithelial cell types as well as transposable element families that are altered significantly in CD in a cell type–specific manner. Finally, through integration with data from genome-wide association studies, we show that genes implicated in CD risk show heretofore unknown cell type–specific patterns of aberrant expression in CD, providing unprecedented insight into the potential biological functions of these genes.ConclusionsSingle-cell analysis shows a number of unexpected cellular and molecular features, including transposable element expression signatures, in the colonic epithelium of treatment-naïve adult CD.

The Impact of Di-Isononyl Phthalate Exposure on Specialized Epithelial Cells in the Colon.

Di-isononyl phthalate (DiNP) is a high-molecular-weight phthalate commonly used as a plasticizer for polyvinyl chloride and other end products, such as medical devices and construction materials. Most of our initial exposure to DiNP occurs by ingestion of DiNP-contaminated foods. However, little is known about the effects of DiNP on the colon. Therefore, the goal of this study was to test the hypothesis that DiNP exposure alters immune responses and impacts specialized epithelial cells in the colon. To test this hypothesis, adult female mice were orally dosed with corn-oil vehicle control or doses of DiNP ranging from 20 µg/kg/d to 200 mg/kg/d for 10-14 days. After the dosing period, mice were euthanized in diestrus, and colon tissues and sera were collected for histological, genomic, and proteomic analysis of various immune factors and specialized epithelial cells. Subacute exposure to DiNP significantly increased protein levels of Ki67 and MUC2, expression of a Paneth cell marker (Lyz1), and estradiol levels in sera compared with control. Gene expression of mucins (Muc1, Muc2, Muc3a, and Muc4), Toll-like receptors (Tlr4 and Tlr5), and specialized epithelial cells (ChgA, Lgr5, Cd24a, and Vil1) were not significantly different between treatment groups and control. Cytokine levels of IL-1RA and CXCL12 were also not significantly different between DiNP treatment groups and control. These data reveal that DiNP exposure increases circulating estradiol levels and gene expression in specialized epithelial cells with immune response capabilities (eg, goblet and Paneth cells) in the mouse colon, which may initiate immune responses to prevent further damage in the colon.

Linking bacterial enterotoxins and alpha defensin 5 expansion in the Crohn's colitis: A new insight into the etiopathogenetic and differentiation triggers driving colonic inflammatory bowel disease.

Evidence link bacterial enterotoxins to apparent crypt-cell like cells (CCLCs), and Alpha Defensin 5 (DEFA5) expansion in the colonic mucosa of Crohn’s colitis disease (CC) patients. These areas of ectopic ileal metaplasia, positive for Paneth cell (PC) markers are consistent with diagnosis of CC. Retrospectively, we: 1. Identified 21 patients with indeterminate colitis (IC) between 2000–2007 and were reevaluation their final clinical diagnosis in 2014 after a followed-up for mean 8.7±3.7 (range, 4–14) years. Their initial biopsies were analyzed by DEFA5 bioassay. 2. Differentiated ulcer-associated cell lineage (UACL) analysis by immunohistochemistry (IHC) of the CC patients, stained for Mucin 6 (MUC6) and DEFA5. 3. Treated human immortalized colonic epithelial cells (NCM460) and colonoids with pure DEFA5 on the secretion of signatures after 24hr. The control colonoids were not treated. 4. Treated colonoids with/without enterotoxins for 14 days and the spent medium were collected and determined by quantitative expression of DEFA5, CCLCs and other biologic signatures. The experiments were repeated twice. Three statistical methods were used: (i) Univariate analysis; (ii) LASSO; and (iii) Elastic net. DEFA5 bioassay discriminated CC and ulcerative colitis (UC) in a cohort of IC patients with accuracy. A fit logistic model with group CC and UC as the outcome and the DEFA5 as independent variable differentiator with a positive predictive value of 96 percent. IHC staining of CC for MUC6 and DEFA5 stained in different locations indicating that DEFA5 is not co-expressed in UACL and is therefore NOT the genesis of CC, rather a secretagogue for specific signature(s) that underlie the distinct crypt pathobiology of CC. Notably, we observed expansion of signatures after DEFA5 treatment on NCM460 and colonoids cells expressed at different times, intervals, and intensity. These factors are key stem cell niche regulators leading to DEFA5 secreting CCLCs differentiation ‘the colonic ectopy ileal metaplasia formation’ conspicuously of pathogenic importance in CC.

A149 TRP53 LOSS IN KRT15+ INTESTINAL STEM CELLS SEVERELY AFFECTS SECRETORY CELL FATE AND SELF-RENEWAL

Abstract Background Intestinal epithelium homeostasis is maintained by two main populations of stem cells: Lgr5+ and reserve stem cells. Under injury, cell plasticity has been observed in progenitor and differentiated cells. We recently reported that Krt15+ cells are present in small intestinal and colon epithelia, and harbor self-renewal, multipotent and regenerative capacities. As in Lgr5+and reserve stem cells, hyperactivation of Wnt/b-catenin pathway in Krt15+ stem cells lead to tumor formation in the intestinal epithelium. While these intestinal stem cell populations can act as tumor-initiating cells in sporadic colon cancer, little is known about the cell-of-origin of colitis-associated colon cancer (CAC). TP53 alteration is reported as an early event in CAC. Therefore, we hypothesize that Trp53 loss specifically in Krt15+ stem cells will perturb the epithelial homeostasis and lead to tumor formation. Aims Identify if Krt15+ cells may act as the cell-of-origin in colitis-associated colorectal cancer Methods To induce Trp53 loss specifically in Krt15+ cells, we generated Krt15-CrePR1;Trp53fl/fl (Krt15△Trp53) mice, induced Cre recombination by injecting RU486 (PR agonist) and euthanized the mice at different time points following recombination. Results Results Twelve-month following Cre recombination, adenoma formation was observed in a small proportion of Krt15△Trp53 mice. Though, Trp53 loss in Krt15+ cells severely perturbed the small intestinal morphology in every mouse studied. Increased crypt length and villi width was observed in Krt15△Trp53 vs control mice without any changes in cell proliferation. We also observed an increased number of Tuft cells and goblet cells in the villi of experimental mice. In the crypt, higher number of Paneth cells and aberrant presence of goblet cells were noted in Krt15△Trp53mice. Interestingly, we also observed crypt cells expressing goblet and Paneth cell markers and decreased Notch pathway activation suggesting dysregulation of secretory cell fate. Krt15△Trp53 mice display higher number of fibroblasts in the villi and the submucosa, as well as thickening of the muscularis layer. Interestingly, similar observations (accumulation of secretory cells and fibrosis) have been reported in IBD patients, supporting the possible role of Krt15+ cells in CAC. Furthermore, crypts isolated from Krt15△Trp53 mice rapidly die when seeded as organoids vs crypts from control mice, suggesting that the alterations observed in vivo in Paneth cells might interfere with the stem cell niche and therefore reduce self-renewal of Krt15+ cells. Conclusions Trp53 loss specifically in Krt15+ cells impaired cell fate decision, induced secretory cell hyperplasia, affected self-renewal ability, and initiated adenoma formation supporting the possible role of Krt15+ cells in gut inflammation and cancer. Funding Agencies Canada Research Chair, Cancer Research Society, CFI

P63 Deficiency and CDX2 Overexpression Lead to Barrett's-Like Metaplasia in Mouse Esophageal Epithelium.

The cellular origin and molecular mechanisms of Barrett's esophagus (BE) are still controversial. Trans-differentiation is a mechanism characterized by activation of the intestinal differentiation program and inactivation of the squamous differentiation program. Renal capsule grafting (RCG) was used to elucidate whether CDX2 overexpression on the basis of P63 deficiency in the esophageal epithelium may generate intestinal metaplasia. P63-/-;Villin-Cdx2 embryos were generated by crossing P63+/- mice with Villin-Cdx2 mice. E18.5 esophagus was xenografted in a renal capsule grafting (RCG) model. At 1, 2, or 4weeks after RCG, the mouse esophagus was immunostained for a proliferation marker (BrdU), squamous transcription factors (SOX2, PAX9), squamous differentiation markers (CK5, CK4, and CK1), intestinal transcription factors (CDX1, HNF1α, HNF4α, GATA4, and GATA6), intestinal columnar epithelial cell markers (A33, CK8), goblet cell marker (MUC2, TFF3), Paneth cell markers (LYZ and SOX9), enteroendocrine cell marker (CHA), and Tuft cell marker (DCAMKL1). The P63-/-;Villin-Cdx2 RCG esophagus was lined with proliferating PAS/AB+ cuboidal cells and formed an intestinal crypt-like structure. The goblet cell markers (TFF3 and MUC2) and intestinal transcription factors (CDX1, HNF1α, HNF4α, GATA4, and GATA6) were expressed although no typical morphology of goblet cells was observed. Other intestinal cell markers including enteroendocrine cell marker (CHA), Paneth cell markers (LYZ and Sox9), and intestinal secretory cell marker (UEA/WGA) were also expressed in the P63-/-;Villin-Cdx2 RCG esophagus. Squamous cell markers (PAX9 and SOX2) were also expressed, suggesting a transitional phenotype. CDX2 overexpression on the basis of P63 deficiency in esophageal epithelial cells induces Barrett's-like metaplasia in vivo. Additional factors may be needed to drive this transitional phenotype into full-blown BE.

Abstract 2365: Does a combination of type 2 diabetes mellitus and increased alcohol intake affect prospective total adenoma accumulation

Abstract Introduction: Adenoma formation data in diabetics is inconclusive. Alcohol intake (AI), associated with colorectal neoplasia (CRN) has not been systematically studied in diabetes. We investigated effects of diabetes and AI in a prospective patient cohort at increased CRN risk. Methods: Diabetes diagnoses based on patients' problem list, corroborated by HbA1c and glucose levels. Self-reported AI was quantified as more than occasional/social. Cumulative adenoma number were computed using available records. In a subset of patients, CRN-related Paneth cell marker p87 was used to semi-quantify immunohistochemically the colonic regions binding this label. Results: 680 patients (348 diabetics 332 non-diabetic) were ascertained with 12.4-year median follow-up. Diabetics had more adenomas than non-diabetics (2.3±3.54 versus 1.81±2.91, p=0.05) and p87 levels were significantly higher in the descending colon (p<0.03) and rectum (p<0.008). Significant demographic differences of increased black ethnicity, lesser survival, increased BMI and increased smoking were appreciated in diabetics. In non-drinking patients, adenomas were also similarly increased in diabetics and demographics and p87 levels were as reported above without significant smoking differences. Comparing diabetics who drank actively with non-diabetics who did not, the diabetics had increased polyp accumulation (2.90±4.29 versus 1.62±2.45 p<0.012), increased proportion of black ethnicity, increased BMI and were younger. Rectal p87 was significantly increased (p<0.04) without smoking effects on polyp number. Conclusion: Diabetics accumulate more adenomas than controls which is reflected in the increase of left-sided p87 expression. A combination of increased AI and diabetes particularly increases adenoma formation seemingly independent of factors such as age and smoking. Citation Format: Martin Tobi, Fadi Antaki, Stephanie Judd, Paula Sochacki, MaryAnn Rambus, Harvinder Talwar, Michael Lawson, Edi Levi, Benita McVicker. Does a combination of type 2 diabetes mellitus and increased alcohol intake affect prospective total adenoma accumulation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2365.