Rectal nitric oxide and fecal calprotectin in inflammatory bowel disease.

OBJECTIVE: The assessment of intestinal inflammation in patients with inflammatory bowel disease (IBD) remains a difficult challenge. Both rectal nitric oxide (NO) and fecal calprotectin can be measured using non-invasive methods and are emerging as promising inflammatory markers in IBD. In this study the aim was to compare calprotectin and NO levels in IBD patients. MATERIAL AND METHODS: Rectal NO was measured tonometrically in 23 healthy volunteers and 32 patients with IBD. In addition, we collected stool samples from all subjects for measurement of fecal calprotectin and nitrate/nitrite (NO metabolites). RESULTS: Patients with IBD had greatly increased NO and calprotectin levels compared to healthy volunteers (p <0.001). In addition, the nitrate levels were slightly increased in IBD patients. A weak correlation was found between rectal NO levels, disease activity and number of loose stools in IBD patients (Spearman's rho 0.37 and 0.51, respectively; p <0.05). Fecal calprotectin correlated only with age (Spearman's rho 0.51; p <0.01). However, no correlation was found between NO and calprotectin. CONCLUSIONS: Both rectal NO and fecal calprotectin are greatly increased during bowel inflammation, but they may reflect different parts of the inflammatory process. Future studies will elucidate the clinical usefulness of these two markers.

Protection from nonsteroidal anti-inflammatory drug (NSAID)-induced gastric ulcers by dietary nitrate.

Nitrate is abundant in our diet with particularly high levels in many vegetables. Ingested nitrate is concentrated in saliva and reduced to nitrite by bacteria in the oral cavity. We recently reported that application of nitrite-containing saliva to the gastric mucosa increases superficial blood flow and mucus generation via acid-catalyzed formation of bioactive nitrogen oxides including nitric oxide. Here we studied if dietary supplementation with nitrate would protect against gastric damage caused by a nonsteroidal anti-inflammatory drug. Rats received sodium nitrate in the drinking water for 1 week in daily doses of 0.1 or 1 mmol kg(-1). Control rats received 1 mmol kg(-1) sodium chloride. Diclofenac (30 mg kg(-1)) was then given orally and the animals were examined 4 h later. In separate experiments we studied the effects of dietary nitrate on intragastric NO levels and mucus formation. Luminal levels of NO gas were greatly increased in nitrate-fed animals. The thickness of the mucus layer increased after nitrate supplementation and gene expression of MUC6 was upregulated in the gastric mucosa. Nitrate pretreatment dose dependently and potently reduced diclofenac-induced gastric lesions. Inflammatory activity was reduced in the rats receiving nitrate as indicated by lower mucosal myeloperoxidase activity and expression of inducible NO synthase. We conclude that dietary nitrate protects against diclofenac-induced gastric ulcers likely via enhanced nitrite-dependent intragastric NO formation and concomitant stimulation of mucus formation. Future studies will reveal if a diet rich in nitrate can offer an additional nutritional approach to preventing and treating peptic ulcer disease.

Rectal mucosal nitric oxide in differentiation of inflammatory bowel disease and irritable bowel syndrome.

BACKGROUND & AIMS: Differentiating patients with functional bowel disorders from those with inflammatory bowel disease (IBD) can be difficult. Rectal luminal levels of nitric oxide (NO) are greatly increased in IBD. To further evaluate this disease marker, we compared NO in patients with irritable bowel syndrome (IBS) with those found in patients with active IBD and in healthy control subjects. METHODS: Rectal NO was measured with chemiluminescence technique by using a tonometric balloon method in 28 healthy volunteers, 39 patients with IBS, 86 with IBD (Crohn's disease and ulcerative colitis), and 12 patients with collagenous colitis. In addition, NO was measured before and after a 4-week treatment period in patients with active ulcerative colitis and repeatedly during 2 weeks in healthy volunteers. RESULTS: NO was low in healthy control subjects (median, 45; 25th-75th percentile, 34-64 parts per billion [ppb]), and variations over time were small. In IBS patients NO was slightly increased (150, 53-200 ppb; P < .001), whereas patients with active IBD or collagenous colitis had greatly increased NO levels (3475, 575-8850 ppb, and 9950, 4475-19,750 ppb, respectively; P < .001). With a cutoff level of 250 ppb, NO had a sensitivity of 95% and a specificity of 91% in discriminating between active bowel inflammation and IBS. Rectal NO correlated with disease activity in IBD and collagenous colitis and decreased markedly in IBD patients responding to anti-inflammatory treatment. CONCLUSIONS: Rectal NO is a minimally invasive and rapid tool for discriminating between active bowel inflammation and IBS and a possibly useful add-on for monitoring patients with IBD.

Gastrointestinal nitric oxide generation in germ-free and conventional rats.

Nitric oxide (NO) is a central mediator of various physiological events in the gastrointestinal tract. The influence of the intestinal microflora for NO production in the gut is unknown. Bacteria could contribute to this production either by stimulating the mucosa to produce NO, or they could generate NO themselves. Using germ-free and conventional rats, we measured gaseous NO directly in the gastrointestinal tract and from the luminal contents using a chemiluminescence technique. Mucosal NO production was studied by using an NO synthase (NOS) inhibitor, and to evaluate microbial contribution to the NO generation, nitrate was given to the animals. In conventional rats, luminal NO differed profoundly along the gastrointestinal tract with the greatest concentrations in the stomach [>4,000 parts per billion (ppb)] and cecum (approximately 200 ppb) and lower concentrations in the small intestine and colon (< or =20 ppb). Cecal NO correlated with the levels in incubated luminal contents. NOS inhibition lowered NO levels in the colon, without affecting NO in the stomach and in the cecum. Gastric NO increased greatly after a nitrate load, proving it to be a substrate for NO generation. In germ-free rats, NO was low (< or =30 ppb) throughout the gastrointestinal tract and absent in the incubated luminal contents. NO also remained low after a nitrate load. Our results demonstrate a pivotal role of the intestinal microflora in gastrointestinal NO generation. Distinctly compartmentalized qualitative and quantitative NO levels in conventional and germ-free rats reflect complex host microbial cross talks, possibly making NO a regulator of the intestinal eco system.

An anthroposophic lifestyle and intestinal microflora in infancy.

The intestinal flora is considered to have an impact on the development of the immune system. In the anthroposophic lifestyle, a diet comprising vegetables spontaneously fermented by lactobacilli, and a restrictive use of antibiotics, anti-pyretics and vaccinations, is typical. The aim of this study was to assess the gut flora in infants in relation to certain lifestyle characteristics associated with anthroposophy. Sixty-nine children < 2 years of age with an anthroposophic lifestyle, and 59 infants of a similar age with a traditional lifestyle, were clinically examined and questionnaire replies assessed. Fecal samples were analyzed by bacterial enumeration, bacterial typing through biochemical fingerprinting and by measuring microflora-associated characteristics (MACs). The numbers of colony-forming units (CFU)/g of feces were significantly higher for enterococci and lactic acid bacteria in children who had never been exposed to antibiotics (5.5 x 107 vs. 2.1 x 107; p < 0.001 and 10 x 107 vs. 4.1 x 107; p < 0.01, respectively). Furthermore, the number of enterococci was significantly higher in breastfed and vegetarian infants (p < 0.01). The diversity (Simpson's diversity index) of lactobacilli, as determined by biochemical fingerprinting, was higher in infants born at home than in those born in hospital (p < 0.01). Several MACs were related to specific lifestyle features, and infants with an anthroposophic lifestyle had a higher proportion of acetic acid and a lower proportion of propionic acid in their stool as compared to the control children. In conclusion, lifestyle factors related to the anthroposophic way of life influenced the composition of the gut flora in the infants. These differences may contribute to the lower prevalence of atopic disease previously observed in children in anthroposophic families.