Acriticalfunctionoftheintestinalmucosaistoformabarrierthatseparatesluminalcontentsfromtheinterstitium.Thesinglelayerofintestinalepithelialcells(IECs)servesasadynamicinterfacebetweenthehostanditsenvironment.Cellpolarityandstructuralpropertiesoftheepitheliumiscomplexandisimportantinthedevelopmentofepithelialbarrierfunction.Epithelialcellsassociatewitheachotherviaaseriesofintercellularjunctions.TheapicalmostintercellularjunctionalcomplexreferredtoastheApicalJunctionComplex(AJC)isimportantinnotonlycell-cellrecognition,butalsointheregulationofparacellularmovementoffluidandsolutes.Defectsintheintestinalepithelialbarrierfunctionhavebeenobservedinanumberofintestinaldisorderssuchasinflammatoryboweldisease(IBD).ItisnowbecomingevidentthatanaberrantepithelialbarrierfunctionplaysacentralroleinthepathophysiologyofIBD.Thus,abetterunderstandingoftheintestinalepithelialbarrierstructureandfunctioninhealthyanddiseasestatessuchasIBDwillfosternewideasforthedevelopmentoftherapiesforsuchchronicdisorders.
