Search

The use of nano- and micro-particulate carriers as delivery systems for oral vaccines has been under investigation for several decades. Surprisingly little is known of their uptake in the human intestine, despite the fact that substantial improvement is required to achieve adequate immune responses in man after oral administration. In this thesis, various aspects of particle transcytosis across the human intestinal epithelium were studied, in order to identify strategies for improved uptake of nano- and micro-particulate drug delivery systems. The follicle associated epithelium (FAE) overlying Peyer´s patches contains M-cells, which have an increased capacity for uptake of particulate antigens. Therefore, a model of human FAE was developed to study mechanisms of particle uptake and transport. Receptors that could be used for targeting to the FAE had previously not been identified in humans. By use of the model FAE, two new targets were identified on human intestinal FAE; CD9 and β1-integrin. Furthermore, studies of isolated human intestinal tissue showed that an integrin-adherent peptide motif, RGD, could be utilized to achieve selective and improved transport of nanoparticles into human Peyer´s patches. Studies of factors influencing intestinal particle uptake and transcytosis revealed that two cytokines, TNF-α and LTα1/β2, but also one growth factor, TGF-β1, induced uptake of particles in Caco-2 cells and transcytosis of particles in the model FAE. Furthermore, it was shown that an enteric bacterium, Yersinia Pseudotuberculosis, could trigger uptake and transcytosis of particles across model absorptive epithelial cells. In conclusion, this thesis provides a platform for further investigations of particle transcytosis across the human intestinal epithelium. The identification of two new proteins with increased expression in human FAE and a targeting sequence that improves particle uptake into Peyer’s patches, gives new hope for the development of subunit oral vacci

The use of nano- and micro-particulate carriers as delivery systems for oral vaccines has been under investigation for several decades. Surprisingly little is known of their uptake in the human intestine, despite the fact that substantial improvement is required to achieve adequate immune responses in man after oral administration. In this thesis, various aspects of particle transcytosis across the human intestinal epithelium were studied, in order to identify strategies for improved uptake of nano- and micro-particulate drug delivery systems. The follicle associated epithelium (FAE) overlying Peyer´s patches contains M-cells, which have an increased capacity for uptake of particulate antigens. Therefore, a model of human FAE was developed to study mechanisms of particle uptake and transport. Receptors that could be used for targeting to the FAE had previously not been identified in humans. By use of the model FAE, two new targets were identified on human intestinal FAE; CD9 and β1-integrin. Furthermore, studies of isolated human intestinal tissue showed that an integrin-adherent peptide motif, RGD, could be utilized to achieve selective and improved transport of nanoparticles into human Peyer´s patches. Studies of factors influencing intestinal particle uptake and transcytosis revealed that two cytokines, TNF-α and LTα1/β2, but also one growth factor, TGF-β1, induced uptake of particles in Caco-2 cells and transcytosis of particles in the model FAE. Furthermore, it was shown that an enteric bacterium, Yersinia Pseudotuberculosis, could trigger uptake and transcytosis of particles across model absorptive epithelial cells. In conclusion, this thesis provides a platform for further investigations of particle transcytosis across the human intestinal epithelium. The identification of two new proteins with increased expression in human FAE and a targeting sequence that improves particle uptake into Peyer’s patches, gives new hope for the development of subunit oral vacci

Intracoronary administration of acetylcholine (Ach) induced QTc interval prolongation in all 14 patients with congenital long QT syndrome (LQTS) and torsade de pointes arrhythmia developed following premature ventricular beats in 5 of the patients. In the experimental models of LQT 2 and LQT 3, tridimensional repolarization mapping showed that three layers having a different electrophysiological character existed in the left ventricle; endocardial (End), midmyocardial M-cell (Mid) and epicardial layer (Epi). The refractory period estimated by the activation-recovery interval (ARI) in the Mid layer was longer than that at Epi/End layers, so marked transmural ARI dispersion was created especially between the Mid and Epi layers at the longer basic drive of 60 bpm. The marked transmural dispersion of repolarization was diminished when the pacing rate changed to 100 bpm. Different from the clinical LQTS patients, intracoronary Ach administration in the LQT models did not show any QTc interval prolongation at lower concentrations. Further, at higher concentrations (＞5μg) of Ach, the Epi layer showed greater ARI abbreviation rather than the Mid/End layers which resulted in greater transmural dispersion of repolarization, but no ventricular arrhythmia was induced.