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EGFR in enterocytes & endothelium and HIF1? in enterocytes are dispensable for massive small bowel resection induced angiogenesis.

ABSTRACT: BACKGROUND:Short bowel syndrome (SBS) results from significant loss of small intestinal length. In response to this loss, adaptation occurs, with Epidermal Growth Factor Receptor (EGFR) being a key driver. Besides enhanced enterocyte proliferation, we have revealed that adaptation is associated with angiogenesis. Further, we have found that small bowel resection (SBR) is associated with diminished oxygen delivery and elevated levels of hypoxia-inducible factor 1-alpha (HIF1?). METHODS:We ablated EGFR in the epithelium and endothelium as well as HIF1? in the epithelium, ostensibly the most hypoxic element. Using these mice, we determined the effects of these genetic manipulations on intestinal blood flow after SBR using photoacoustic microscopy (PAM), intestinal adaptation and angiogenic responses. Then, given that endothelial cells require a stromal support cell for efficient vascularization, we ablated EGFR expression in intestinal subepithelial myofibroblasts (ISEMFs) to determine its effects on angiogenesis in a microfluidic model of human small intestine. RESULTS:Despite immediate increased demand in oxygen extraction fraction measured by PAM in all mouse lines, were no differences in enterocyte and endothelial cell EGFR knockouts or enterocyte HIF1? knockouts by POD3. Submucosal capillary density was also unchanged by POD7 in all mouse lines. Additionally, EGFR silencing in ISEMFs did not impact vascular network development in a microfluidic device of human small intestine. CONCLUSIONS:Overall, despite the importance of EGFR in facilitating intestinal adaptation after SBR, it had no impact on angiogenesis in three cell types-enterocytes, endothelial cells, and ISEMFs. Epithelial ablation of HIF1? also had no impact on angiogenesis in the setting of SBS.

SUBMITTER: Onufer EJ

PROVIDER: S-EPMC7491746 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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EGFR in enterocytes & endothelium and HIF1α in enterocytes are dispensable for massive small bowel resection induced angiogenesis.

Onufer Emily J EJ Aladegbami Bola B Imai Toru T Seiler Kristen K Bajinting Adam A Courtney Cathleen C Sutton Stephanie S Bustos Aiza A Yao Junjie J Yeh Cheng-Hung CH Sescleifer Anne A Wang Lihong V LV Guo Jun J Warner Brad W BW

PloS one 20200915 9

<h4>Background</h4>Short bowel syndrome (SBS) results from significant loss of small intestinal length. In response to this loss, adaptation occurs, with Epidermal Growth Factor Receptor (EGFR) being a key driver. Besides enhanced enterocyte proliferation, we have revealed that adaptation is associated with angiogenesis. Further, we have found that small bowel resection (SBR) is associated with diminished oxygen delivery and elevated levels of hypoxia-inducible factor 1-alpha (HIF1α).<h4>Methods ...[more]

PMID: 32931498

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Project description:Background & aimsThe small intestine (SI) displays regionality in nutrient and immunological function. Following SI tissue loss (as occurs in short gut syndrome, or SGS), remaining SI must compensate, or "adapt"; the capacity of SI epithelium to reprogram its regional identity has not been described. Here, we apply single-cell resolution analyses to characterize molecular changes underpinning adaptation to SGS.MethodsSingle-cell RNA sequencing was performed on epithelial cells isolated from distal SI of mice following 50% proximal small bowel resection (SBR) vs sham surgery. Single-cell profiles were clustered based on transcriptional similarity, reconstructing differentiation events from intestinal stem cells (ISCs) through to mature enterocytes. An unsupervised computational approach to score cell identity was used to quantify changes in regional (proximal vs distal) SI identity, validated using immunofluorescence, immunohistochemistry, qPCR, western blotting, and RNA-FISH.ResultsUniform Manifold Approximation and Projection-based clustering and visualization revealed differentiation trajectories from ISCs to mature enterocytes in sham and SBR. Cell identity scoring demonstrated segregation of enterocytes by regional SI identity: SBR enterocytes assumed more mature proximal identities. This was associated with significant upregulation of lipid metabolism and oxidative stress gene expression, which was validated via orthogonal analyses. Observed upstream transcriptional changes suggest retinoid metabolism and proximal transcription factor Creb3l3 drive proximalization of cell identity in response to SBR.ConclusionsAdaptation to proximal SBR involves regional reprogramming of ileal enterocytes toward a proximal identity. Interventions bolstering the endogenous reprogramming capacity of SI enterocytes-conceivably by engaging the retinoid metabolism pathway-merit further investigation, as they may increase enteral feeding tolerance, and obviate intestinal failure, in SGS.

Project description:Numerous cytokines have been shown to affect epithelial cell differentiation and proliferation through epithelial-mesenchymal interaction. Growing evidence suggests that platelet-derived growth factor (PDGF) signaling is an important mediator of these interactions. The purpose of this study was to evaluate the effect of PDGF-α on enterocyte turnover in a rat model of short bowel syndrome (SBS). Male rats were divided into four groups: Sham rats underwent bowel transection, Sham-PDGF-α rats underwent bowel transection and were treated with PDGF-α, SBS rats underwent a 75% bowel resection, and SBS-PDGF-α rats underwent bowel resection and were treated with PDGF-α. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined at sacrifice. Illumina's Digital Gene Expression (DGE) analysis was used to determine PDGF-related gene expression profiling. PDGF-α and PDGF-α receptor (PDGFR-α) expression was determined using Real Time PCR. Western blotting was used to determine p-ERK, Akt1/2/3, bax and bcl-2 protein levels. SBS rats demonstrated a significant increase in PDGF-α and PDGFR-α expression in jejunum and ileum compared to sham animals. SBS-PDGF-α rats demonstrated a significant increase in bowel and mucosal weight, villus height and crypt depth in jejunum and ileum compared to SBS animals. PDGF-α expression in crypts increased in SBS rats (vs sham) and was accompanied by increased cell proliferation following PDGF-α administration. A significant decrease in cell apoptosis in this group was correlated with lower bax protein levels. In conclusion, in a rat model of SBS, PDGF-α stimulates enterocyte turnover, which is correlated with up-regulated PDGF-α receptor expression in the remaining small intestine. Animals were divided randomly into two experimental groups of 6 rats each. Group A rats underwent bowel transection and re-anastomosis (Sham), Group B animals underwent 75% bowel resection (SBS). Due to the quality of DNA, we performed final analysis from 5 jejunal samples (1 sham and 4 resected rats) and from 7 ileal samples (3 sham and 4 resected rats). Illumina's Digital Gene Expression (DGE) analysis using Illumina Rat Quad BeadChips was used to determine PDGF-related gene expression profiling.

Dataset Information

EGFR in enterocytes & endothelium and HIF1? in enterocytes are dispensable for massive small bowel resection induced angiogenesis.

Publications

EGFR in enterocytes & endothelium and HIF1α in enterocytes are dispensable for massive small bowel resection induced angiogenesis.

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