Glucose transporter expression in the human colon

AIM To investigate by immunostaining glucose transporter expression in human colorectal mucosa in controls and patients with inflammatory bowel disease(IBD). METHODS Colorectal samples were obtained from patients undergoing lower endoscopic colonoscopy or rectosigmoidoscopy. Patients diagnosed with ulcerativecolitis(n = 18) or Crohn's disease(n = 10) and scheduled for diagnostic colonoscopy were enrolled. Patients who underwent colonoscopy for prevention screening of colorectal cancer or were followed-up after polypectomy or had a history of lower gastrointestinal symptoms were designated as the control group(CTRL, n = 16). Inflammatory status of the mucosa at the sampling site was evaluated histologically and/or endoscopically. A total of 147 biopsies of colorectal mucosa were collected and processed for immunohistochemistry analysis. The expression of GLUT2, SGLT1, and GLUT5 glucose transporters was investigated using immunoperoxidase labeling. To compare immunoreactivity of GLUT5 and LYVE-1, which is a marker for lymphatic vessel endothelium, doublelabeled confocal microscopy was used. RESULTS Immunohistochemical analysis revealed that GLUT2, SGLT1, and GLUT5 were expressed only in short epithelial portions of the large intestinal mucosa. No important differences were observed in glucose transporter expression between the samples obtained from the different portions of the colorectal tract and between the different patient groups. Unexpectedly, GLUT5 expression was also identified in vessels, mainly concentrated in specific areas where the vessels were clustered. Immunostaining with LYVE-1 and GLUT5 antibodies revealed that GLUT5-immunoreactive(-IR) clusters of vessels were concentrated in areas internal to those that were LYVE-1 positive. GLUT5 and LYVE-1 did not appear to be colocalized but rather showed a close topographical relationship on the endothelium. Based on their LYVE-1 expression, GLUT5-IR vessels were identified as lymphatic. Both inflamed and noninflamed mucosal colorectal tissue biopsies from the IBD and CTRL patients showed GLUT5-IR clusters of lymphatic vessels. CONCLUSION Glucose transporter immunoreactivity is present in colorectal mucosa in controls and IBD patients. GLUT5 expression is also associated with lymphatic vessels. This novel finding aids in the characterization of lymphatic vasculature in IBD patients.

Noncoding RNAs as drivers of the phenotypic plasticity of oesophageal mucosa

The histological commitment of the lower oesophageal mucosa largely depends on a complex molecular landscape. After extended inflammatory insult due to gastroesophageal reflux disease,squamous oesophageal mucosa may differentiate into columnar metaplastic mucosa. In this setting,the presence of intestinal metaplasia is considered the starting point of Barrett's carcinogenetic cascade. Aside from secondary prevention strategies for Barrett's mucosa(BM) patients,there are multiple endoscopic ablative therapies available for BM eradication and for the replacement of metaplastic epithelia with a neosquamous mucosa. However,BM frequently recurs in a few years,which supports the notable phenotypic plasticity of the oesophageal mucosa. In recent years,several reports pinpointed a class of small noncoding RNAs,the micro RNAs(mi RNAs),as principal effectors and regulators of oesophageal mucosa metaplastic(and neoplastic) transformation. Because of mi RNAs notable stability in fixed archival diagnostic specimens,expression profiling of mi RNAs represent an innovative diagnostic,prognostic and predictive tool in the stratification of phenotypic alterations in the oesophageal mucosa.