Increased activity and expression of iNOS in human duodenal enterocytes from patients with celiac disease.
The activity of nitric oxide synthase (NOS) was assayed in enterocytes isolated from human duodenal biopsies to determine its role in celiac disease. Patients were categorized into groups with irritable bowel syndrome, iron-deficiency anemia, B(12)/folate deficiency, and treated and untreated celiac disease. Enterocytes isolated from all groups showed 1400W-inhibitable Ca2+-independent NOS activity with a pH level and temperature optimum of 9.4 and 37 degrees C, respectively. Western blotting showed that enterocytes expressed the inducible NOS protein and proteins with nitrated tyrosine residues, the latter being indicative of nitric oxide-driven peroxynitrite and/or free-radical damage. Endothelial NOS was seen only in the lamina propria. Patients with celiac disease had higher NOS activity than other patient groups. Treatment of the condition led to a fall in activity. Enzyme-linked immunosorbent assay demonstrated cGMP production by the enterocyte fraction, but cGMP levels did not correlate with NOS activity. These results suggest that inducible NOS is constitutively expressed in human duodenal enterocytes, is increased in patients with untreated celiac disease, and is partially corrected when such patients are treated. We found no evidence to support a role for nitric oxide in the formation of cGMP within the small intestine. Furthermore, we were unable to demonstrate a role for peroxynitrite/free radical damage in the pathophysiology of celiac disease.
David Evans Medical Research Centre, City Hospital, NG5 1PB Nottingham, United Kingdom.
Iain A
IA
Murray
Ian
I
Daniels
Kathryn
K
Coupland
Julie A
JA
Smith
Richard G
RG
Long
D015153:Blotting, Western; D002446:Celiac Disease / Q000201:enzymology* / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004386:Duodenum / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D020895:Enterocytes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D030421:Peroxynitrous Acid / Q000494:pharmacology
D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D006152:Cyclic GMP