IL-1beta causes an increase in intestinal epithelial tight junction permeability.
IL-1beta is a prototypical proinflammatory cytokine that plays a central role in the intestinal inflammation amplification cascade. Recent studies have indicated that a TNF-alpha- and IFN-gamma-induced increase in intestinal epithelial paracellular permeability may be an important mechanism contributing to intestinal inflammation. Despite its central role in promoting intestinal inflammation, the role of IL-1beta on intestinal epithelial tight junction (TJ) barrier function remains unclear. The major aims of this study were to determine the effect of IL-1beta on intestinal epithelial TJ permeability and to elucidate the mechanisms involved in this process, using a well-established in vitro intestinal epithelial model system consisting of filter-grown Caco-2 intestinal epithelial monolayers. IL-1beta (0-100 ng/ml) produced a concentration- and time-dependent decrease in Caco-2 transepithelial resistance. Conversely, IL-1beta caused a progressive time-dependent increase in transepithelial permeability to paracellular marker inulin. IL-1beta-induced increase in Caco-2 TJ permeability was accompanied by a rapid activation of NF-kappaB. NF-kappaB inhibitors, pyrrolidine dithiocarbamate and curcumin, prevented the IL-1beta-induced increase in Caco-2 TJ permeability. To further confirm the role of NF-kappaB in the IL-1beta-induced increase in Caco-2 TJ permeability, NF-kappaB p65 expression was silenced by small interfering RNA transfection. NF-kappaB p65 depletion completely inhibited the IL-1beta-induced increase in Caco-2 TJ permeability. IL-1beta did not induce apoptosis in the Caco-2 cell. In conclusion, our findings show for the first time that IL-1beta at physiologically relevant concentrations causes an increase in intestinal epithelial TJ permeability. The IL-1beta-induced increase in Caco-2 TJ permeability was mediated in part by the activation of NF-kappaB pathways but not apoptosis.
Al-Sadi
Rana M
RM
Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
Ma
Thomas Y
TY
D017209:Apoptosis; D018938:Caco-2 Cells; D003474:Curcumin / Q000494:pharmacology; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D062793:Occludin; D010539:Permeability / Q000187:drug effects; D011759:Pyrrolidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D013859:Thiocarbamates / Q000494:pharmacology; D019108:Tight Junctions / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism
D053583:Interleukin-1beta; D008565:Membrane Proteins; D016328:NF-kappa B; C568985:OCLN protein, human; D062793:Occludin; D011759:Pyrrolidines; D012333:RNA, Messenger; D013859:Thiocarbamates; C020972:pyrrolidine dithiocarbamic acid; D003474:Curcumin