Platelet-Activating Factor Induces TLR4 Expression in Intestinal Epithelial Cells: Implication for the Pathogenesis of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in neonatal intensive care units, however its pathogenesis is not completely understood. We have previously shown that platelet activating factor (PAF), bacteria and TLR4 are all important factors in the development of NEC. Given that Toll-like receptors (TLRs) are expressed at low levels in enterocytes of the mature gastrointestinal tract, but were shown to be aberrantly over-expressed in enterocytes in experimental NEC, we examined the regulation of TLR4 expression and signaling by PAF in intestinal epithelial cells using human and mouse in vitro cell lines, and the ex vivo rat intestinal loop model. In intestinal epithelial cell (IEC) lines, PAF stimulation yielded upregulation of both TLR4 mRNA and protein expression and led to increased IL-8 secretion following stimulation with LPS (in an otherwise LPS minimally responsive cell line). PAF stimulation resulted in increased human TLR4 promoter activation in a dose dependent manner. Western blotting and immunohistochemical analysis showed PAF induced STAT3 phosphorylation and nuclear translocation in IEC, and PAF-induced TLR4 expression was inhibited by STAT3 and NFκB Inhibitors. Our findings provide evidence for a mechanism by which PAF augments inflammation in the intestinal epithelium through abnormal TLR4 upregulation, thereby contributing to the intestinal injury of NEC

Effect of a corticotropin releasing hormone receptor antagonist on colonic sensory and motor function in patients with irritable bowel syndrome

Background and aims: Corticotropin releasing hormone (CRH) is a major mediator of the stress response in the brain-gut axis. Irritable bowel syndrome (IBS) is presumed to be a disorder of the brain-gut link associated with an exaggerated response to stress. We hypothesised that peripheral administration of α-helical CRH (αhCRH), a non-selective CRH receptor antagonist, would improve gastrointestinal motility, visceral perception, and negative mood in response to gut stimulation in IBS patients. Methods: Ten normal healthy subjects and 10 IBS patients, diagnosed according to the Rome II criteria, were studied. The tone of the descending colon and intraluminal pressure of the sigmoid colon were measured at baseline, during rectal electrical stimulation (ES), and at recovery after administration of saline. Visceral perception after colonic distension or rectal ES was evaluated as threshold values on an ordinate scale. The same measurements were repeated after administration of αhCRH (10 μg/kg). Results: ES induced significantly higher motility indices of the colon in IBS patients compared with controls. This response was significantly suppressed in IBS patients but not in controls after administration of αhCRH. Administration of αhCRH induced a significant increase in the barostat bag volume of controls but not in that of IBS patients. αhCRH significantly reduced the ordinate scale of abdominal pain and anxiety evoked by ES in IBS patients. Plasma adrenocorticotropic hormone and serum cortisol levels were generally not suppressed by αhCRH. Conclusion: Peripheral administration of αhCRH improves gastrointestinal motility, visceral perception, and negative mood in response to gut stimulation, without affecting the hypothalamo-pituitary-adrenal axis in IBS patients

Improvement and recent applications of the Tohoku microbeam system

The microbeam system at Tohoku University has been applied to various fields since its installation and is mainly used for biological applications. The primary purpose of this work was to develop a 3D μ-CT, in which a microbeam is used as a monoenergetic point X-ray source. The second one was to develop a microbeam analysis system for biological samples. A beam spot of 0.4 × 0.4 μm2 at a beam current of several tens of pA has been produced. However, in our set-up, μ-PIXE/RBS analyses demand beam currents of ca. 100 pA, which restricts the spatial resolution to around 1 × 1 μm2. In order to get higher spatial resolution down to several hundred nm and higher beam current with a several μm resolution, a triplet lens system was designed and newly installed. This upgrade was carried out simultaneously with the recovery from the damage caused by the great east Japan earthquake. The triplet lens system has larger demagnification and was designed by adding a quadrupole lens to the existing doublet system. Although a beam spot size of 2 × 1 μm2 is currently obtained, it has not achieved the performance obtained by the previous doublet system. The doublet system has been recovered to its previous performance and is routinely applied to simultaneous μ-PIXE/RBS analysis in various fields. Recent applications of 3D-PIXE-μ-CT of toxic elements in single cells with the new microbeam system are presented