Epithelial barrier

When invading microorganisms have crossed the epithelial barriers they will almost certainly be taken up, with lymph, in the lymphatic ducts and be delivered to the filtration and immrme systems of the local lymph nodes. Sometimes this serves to spread infections... 

E. R. Cooper, Optimization of Transport and Biological Response with Epithelial Barriers in Biological and Synthetic Membranes, Alan R. Liss, New York, 1989, pp. 249-260. 

Several of the postulated roles for nematode-secreted AChEs assume that they gain access to the intestinal mucosa. Several possibilities exist for transport of parasite AChE across the epithelial cell barrier, such as (i) utilization of existing pathways for receptor-mediated transcytosis (ii) a paracellular route facilitated by parasite-secreted proteases as observed for a bacterial elastase (Azghani et al., 1993) and (iii) increased paracellular permeability resulting from inflammatory events in the mucosa. We consider the latter suggestion most likely, as this has been duplicated by ex vivo perfusion with rat mast cell protease II (Scudamore et al., 1995). Moreover, cholinergic stimulation attenuates epithelial barrier properties to macromolecules in rat ileal crypts (Phillips et al., 1987). 

Neutra, M.R., Pringault, E. and Kraehenbuhl, J.P. (1996) Antigen sampling across epithelial barriers and induction of mucosal immune responses. Annual Review of Immunology 14, 275-300. 

Kindon, H., Pothoulakis, C., Thim, L., Lynch-Devaney, K. and Podolsky, D.K. (1995) Trefoil peptide protection of intestinal epithelial barrier function cooperative interaction with mucin glycoprotein. Gastroenterobgy 109, 516-523. 

I. Williamson, R. Shah, M. MacKay, and P. Artursson. Transport and permeability properties of human Caco-2 cells an in vitro model of the intestinal epithelial barrier, J. Control. Release 1990, 33, 25-40... 

Law S, Wertz PW, Swartzendruber DC, Squier CA (1995) Regional variation in content, composition and organization of porcine epithelial barrier lipids revealed by thin-layer chromatography and transmission electron microscopy. Arch Oral Biol 40 1085-1091... 

Tukker JJ (2002) Characterization of transport over epithelial barriers. In Lehr CM (Ed) Cell Culture Models of Biological Barriers. In-vitro Test Systems for Drug Absorption and Delivery. Taylor and Francis, London, pp 52-61. 

There are two routes potentially involved in drug absorption across the nasal epithelial barrier the transcellular and paracellular routes [20], Several experimental evidences dealing with the mechanism of transnasal permeation support the existence of both lipoidal pathyway (i.e., transcellular route) and an aqueous pore pathway (i.e., paracellular route). 

A relatively new cell line that has not to date been characterised for its use in biopharmaceutics is based on primary airway epithelial cells infected with retroviruses expressing hTERT and HPV-16 E6/E7 (NuLi-1) [54], NuLi-1 cells were cultured on plastic up to passage 30. When grown on collagen-coated, semi-permeable membranes (Millicell-PCF), NuLi-1 TEER decreased only slightly over the 30 passages from 685 31 to 389 21 ohm.cm2. The TEER of NuLi-1 is similar to that observed with the primary bronchial cultures of 532 147 ohm.cm2. Thus, NuLi-1 cells can form an electrically tight airway epithelial barrier that mimics active and passive ion transport properties of primary human bronchial epithelial cells [54],... 

Use of In Vitro Models of Tracheo-Bronchial Epithelial Barriers in Biopharmaceutical Research... 

Grainger Cl, Greenwell LL, Lockley DJ, Martin GP, Forbes B (2006) Culture of Calu-3 cells at the air interface provides a representative model of the airway epithelial barrier. Pharm Res 23(7) 1482-1490. 

Chapter 11 In Vitro Models of the Alveolar Epithelial Barrier 259... 

Alveolar epithelial cells (AECs) are connected with each other by various epithelial cell-cell contacts (i.e., tight junctions, adherens junctions and others). These contacts comprise several groups of proteins, such as occludin, zonula occludens (ZO-1, -2, -3), claudins, tricellulin, E-cadherin and intercellular adhesion molecule-1 (ICAM-1) [13-15], Their regulation and interplay, which has influence on epithelial barrier properties, however, is largely unknown to date. 

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