Transcription factor TFEB cell-autonomously modulates susceptibility to intestinal epithelial cell injury in vivo

Understanding the transcription factors that modulate epithelial resistance to injury is necessary for understanding intestinal homeostasis and injury repair processes. Recently, transcription factor EB (TFEB) was implicated in expression of autophagy and host defense genes in nematodes and mammalian cells. However, the in vivo roles of TFEB in the mammalian intestinal epithelium were not known. Here, we used mice with a conditional deletion of Tfeb in the intestinal epithelium (Tfeb ΔIEC) to examine its importance in defense against injury. Unperturbed Tfeb ΔIEC mice exhibited grossly normal intestinal epithelia, except for a defect in Paneth cell granules. Tfeb ΔIEC mice exhibited lower levels of lipoprotein ApoA1 expression, which is downregulated in Crohn’s disease patients and causally linked to colitis susceptibility. Upon environmental epithelial injury using dextran sodium sulfate (DSS), Tfeb ΔIEC mice exhibited exaggerated colitis. Thus, our study reveals that TFEB is critical for resistance to intestinal epithelial cell injury, potentially mediated by APOA1

Distinct expression patterns of Notch ligands, Dll1 and Dll4, in normal and inflamed mice intestine

Reports have suggested that the two Notch ligands, Dll1 and Dll4, are indispensable to maintain the homeostasis of the intestinal epithelium. However, within the intestinal epithelium, the precise distribution of the cells that express those ligands at the protein level remains largely unknown. Here, we show a series of immunohistochemical analysis through which we successfully identified mice intestinal epithelial cells (IECs) that endogenously express Dll1 or Dll4. Results showed that Dll1-positive (Dll1+ve) IECs reside exclusively within the crypt, whereas Dll4-positive (Dll4+ve) IECs can locate both in the crypt and in the villus of the small intestine. Also in the colon, Dll1+ve IECs resided at the lower part of the crypt, whereas Dll4+ve IECs resided at both upper and lower part of the crypt, including the surface epithelium. Both Dll1+ve and Dll4+ve IECs were ATOH1-positive, but Hes1-negative cells, and located adjacent to Hes1-positive cells within the crypts. A sub-population of both Dll1+ve and Dll4+ve IECs appeared to co-express Muc2, but rarely co-expressed other secretory lineage markers. However, as compared to Dll1+ve IECs, Dll4+ve IECs included larger number of Muc2-postive IECs, suggesting that Dll4 is more preferentially expressed by goblet cells. Also, we identified that Dll4 is expressed in the Paneth cells of the small intestine, whereas Dll1 and Dll4 is expressed in the c-kit-positive IECs of the colon, indicating that Dll1+ve and Dll4+ve IECs may contribute to constitute the intestinal stem cell niche. Compared to the normal colon, analysis of DSS-colitis showed that number of Dll1+ve IECs significantly decrease in the elongated crypts of the inflamed colonic mucosa. In sharp contrast, number of Dll4+ve IECs showed a significant increase in those crypts, which was accompanied by the increase in number of Hes1-positive IECs. Those Dll4+ve IECs were mostly found adjacent to the Hes1-positive IECs, suggesting that Dll4 may act as a major Notch ligand in the crypts of the inflamed colonic mucosa. Our results illustrate distinct expression patterns of Dll1 and Dll4 within the intestinal epithelium, and suggest that these two ligands may have different roles in normal and inflamed mucosa

Efficacy and safety of repeated endoscopic radial incision and cutting procedure for benign esophageal stricture

Background: Radial incision and cutting (RIC) is indicated for refractory benign esophageal strictures after curative treatment for esophageal cancer and has shown favorable short-term outcomes. However, re-stricture after RIC may occur in the long term, and RIC is performed repeatedly in such cases, but the efficacy and safety of repeated RIC are unclear. Therefore, we aimed to demonstrate the efficacy and safety of the repeated RIC for refractory benign esophageal strictures after surgical and non-surgical treatment. Methods: Between April 2008 and September 2019, we enrolled patients who were treated with the first RIC for benign esophageal strictures. The RIC was indicated for the refractory stricture and repeatedly performed for re-refractory esophageal stricture after RIC. We retrospectively evaluated the 6-month refractory stricture-free rate, and adverse events in the first RIC and repeated RICs. Results: Forty-six patients (39 men, 7 women; median age, 71 years, range 49–85) were included. RIC was performed once in 24 patients (non-repeated RIC group) and two or more times in 22 patients (repeated RIC group). In all patients, the 6-month refractory stricture-free rate after the first RIC were 42.3%. In the repeated RIC group, the 6-month refractory stricture-free rate after the first and repeated RICs were 18.2% vs 18.2%, respectively. No adverse events were noted. Conclusions: The repeated RIC could not be a curative treatment, but can be effective in the short-term and safe, even for patients with refractory benign esophageal stricture after the first RIC

Contribution of ATOH1+ Cells to the Homeostasis, Repair, and Tumorigenesis of the Colonic Epithelium

Summary: ATOH1 is a master transcription factor for the secretory lineage differentiation of intestinal epithelial cells (IECs). However, the comprehensive contribution of ATOH1+ secretory lineage IECs to the homeostasis, repair, and tumorigenesis of the intestinal epithelium remains uncertain. Through our ATOH1+ cell-lineage tracing, we show here that a definite number of ATOH1+ IECs retain stem cell properties and can form ATOH1+IEC-derived clonal ribbons (ATOH1+ICRs) under completely homeostatic conditions. Interestingly, colonic ATOH1+ IECs appeared to exhibit their stem cell function more frequently compared with those of the small intestine. Consistently, the formation of ATOH1+ICRs was significantly enhanced upon dextran sodium sulfate colitis-induced mucosal damage. In addition, colonic ATOH1+ IECs acquired tumor stem cell-like properties in the azoxymethane-DSS tumor model. Our results reveal an unexpected contribution of colonic ATOH1+ IECs to maintaining the stem cell population under both homeostatic and pathologic conditions and further illustrate the high plasticity of the crypt-intrinsic stem cell hierarchy

Lineage-specific expression of bestrophin-2 and bestrophin-4 in human intestinal epithelial cells.

Intestinal epithelial cells (IECs) regulate the absorption and secretion of anions, such as HCO3(-) or Cl(-). Bestrophin genes represent a newly identified group of calcium-activated Cl(-) channels (CaCCs). Studies have suggested that, among the four human bestrophin-family genes, bestrophin-2 (BEST2) and bestrophin-4 (BEST4) might be expressed within the intestinal tissue. Consistently, a study showed that BEST2 is expressed by human colonic goblet cells. However, their precise expression pattern along the gastrointestinal tract, or the lineage specificity of the cells expressing these genes, remains largely unknown. Here, we show that BEST2 and BEST4 are expressed in vivo, each in a distinct, lineage-specific manner, in human IECs. While BEST2 was expressed exclusively in colonic goblet cells, BEST4 was expressed in the absorptive cells of both the small intestine and the colon. In addition, we found that BEST2 expression is significantly down-regulated in the active lesions of ulcerative colitis, where goblet cells were depleted, suggesting that BEST2 expression is restricted to goblet cells under both normal and pathologic conditions. Consistently, the induction of goblet cell differentiation by a Notch inhibitor, LY411575, significantly up-regulated the expression of not BEST4 but BEST2 in MUC2-positive HT-29 cells. Conversely, the induction of absorptive cell differentiation up-regulated the expression of BEST4 in villin-positive Caco-2 cells. In addition, we found that the up- or down-regulation of Notch activity leads to the preferential expression of either BEST4 or BEST2, respectively, in LS174T cells. These results collectively confirmed that BEST2 and BEST4 could be added to the lineage-specific genes of humans IECs due to their abilities to clearly identify goblet cells of colonic origin and a distinct subset of absorptive cells, respectively