NAD+ ameliorates inflammation-induced epithelial barrier dysfunction in cultured enterocytes and mouse ileal mucosa.
In the course of other experiments, we serendipitously observed that extracellular nicotinamide adenine dinucleotide (NAD+) ameliorated the development of epithelial hyperpermeability when monolayers of Caco-2 enterocyte-like cells were incubated with cytomix, a mixture containing interferon-gamma, interleukin-1beta, and tumor necrosis factor-alpha. We sought to characterize the effects of NAD+ on inflammation-induced epithelial barrier dysfunction using Caco-2 monolayers that were exposed to cytomix in the absence or presence of NAD+ or other purine-containing molecules. Paracellular barrier function measured as the apical-to-basolateral passage of fluorescein isothiocyanate-conjugated dextran (mol. wt. approximately 4000) was preserved in a concentration-dependent manner when immunostimulated Caco-2 cells were exposed to extracellular NAD+. Incubation with NAD+ prevented cytomix-induced derangements in the expression and localization of the tight junction proteins occludin and zonula occludens-1 in Caco-2 cells. Treatment of cytomix-stimulated cells with NAD+ also blocked nuclear factor-kappaB (NF-kappaB) activation, inducible nitric-oxide synthase induction, and increased production of nitric oxide (NO.). Ileal mucosal permeability to fluorescein isothiocyanate-dextran mol. wt. approximately 4000 was increased in mice 18 h after lipopolysaccharide (endotoxin) injection, but treatment of endotoxemic mice with NAD+ ameliorated the development of gut mucosal hyperpermeability. Thus, extracellular NAD+ seems to ameliorate inflammation-induced intestinal epithelial barrier dysfunction by inhibiting NF-kappaB activation and increased NO. production.
Han
Xiaonan
X
Department of Critical Care Medicine, School of Medicine, University of Pittsburgh, 3550 Terrace St., Pittsburgh, PA 15261.
Uchiyama
Takashi
T
Sappington
Penny L
PL
Yaguchi
Arino
A
Yang
Runkuan
R
Fink
Mitchell P
MP
Delude
Russell L
RL
D000818:Animals; D018938:Caco-2 Cells; D004347:Drug Interactions; D020895:Enterocytes / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D007082:Ileum / Q000473:pathology; D007114:Immunization; D007249:Inflammation; D007413:Intestinal Mucosa / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009243:NAD / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism
D016328:NF-kappa B; D009243:NAD; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse