Mucosal NOD2 expression and NF-kappaB activation in pediatric Crohn's disease

BACKGROUND

Recent advances in the pathogenesis of Crohn's disease (CD) have suggested that an aberrant innate immune response initiates the cascade of events leading to T-cell activation and to disease development. NOD2 protein, which is mainly expressed by innate immunity cells, appears to play a key role against bacteria by triggering a host defense response through the activation of the transcriptor factor NF-kappaB and a consequent proinflammatory cytokine production. The present study was aimed at investigating the expression and activity of NOD2, NF-kappaB, and of 2 proinflammatory cytokines, TNFalpha and IL-1beta, in mucosal biopsies of CD affected children compared to healthy controls.

METHODS

In all, 22 children with active CD and 10 matched controls were entered in the study. mRNA and protein expressions were detected using reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot; NF-kappaB binding activity was assessed by electromobility gel shift assay (EMSA).

RESULTS

NOD2 and IL-1beta mRNAs were upregulated in CD children. Protein levels of NOD2, TNFalpha, and nuclear NF-kappaB, as well as the binding activity of NF-kappaB to a consensus DNA sequence, were significantly increased in inflamed mucosa of patients as compared to controls. Moreover, NF-kappaB activity was strongly upregulated in patients also when bound to the NOD2 promoter site. No difference was seen between patients and controls when NF-kappaB binding activity was determined in the uninflamed tissue.

CONCLUSIONS

This study suggests that altered mechanisms regulating NOD2 induction, NF-kappaB activation and cytokine production may contribute to dysregulate the innate immune response underlying pediatric CD.

Polymeric diet alone versus corticosteroids in the treatment of active pediatric Crohn's disease: a randomized controlled open-label trial

BACKGROUND & AIMS

Nutritional therapy has been reported to have an almost equivalent efficacy of corticosteroids in achieving clinical remission in active Crohn's disease (CD). However, the effects of both treatments on intestinal mucosal inflammation rarely are reported. In a randomized controlled trial in children with active CD we compared the efficacy of nutritional therapy alone or corticosteroids on clinical variables and intestinal mucosal healing.

METHODS

In a prospective, 10-week open-label trial, children with active, naive CD were randomized to orally polymeric formula alone or oral corticosteroids. The clinical activity index and nutritional and activity serum variables were evaluated at week 0 and then every 2 weeks; intestinal mucosal inflammation was assessed through endoscopy and histology at weeks 0 and 10. Primary efficacy outcomes were clinical remission and mucosal healing.

RESULTS

Of the 37 children randomized, 19 received polymeric formula and 18 received corticosteroids. At week 10, on an intention-to-treat basis, the proportion of patients achieving clinical remission was comparable between the 2 groups (polymeric formula: 15/19 [79%; 95% confidence interval (CI), 56%-92%]; corticosteroid group: 12/18 [67%; 95% CI, 44%-84%]; P = .4; not significant). On the contrary, the proportion of children showing mucosa healing was significantly higher in the polymeric (14/19; 74%; 95% CI, 51%-89%) than the corticosteroid group (6/18 [33%; 95% CI, 16%-57%]; P < .05). At week 10 both endoscopic and histologic scores significantly decreased only in the polymeric group (P < .001).

CONCLUSIONS

In children with active and recently diagnosed CD, a short course of polymeric diet is more effective than corticosteroids in inducing healing of gut inflammatory lesions.

Anticatabolic effect of branched-chain amino acid-enriched solutions in patients with liver cirrhosis

An amino acid mixture rich in branched-chain amino acids and poor in aromatic amino acids was infused in six cirrhotics with altered plasma amino acid profile and normal mental state. The effect on muscle protein catabolism, as measured by urinary excretion of 3-methylhistidine, was assessed during two consecutive 3-day period in which patients received the amino acid mixture alone or in a hypertonic dextrose solution. During a 3-day basal period, cirrhotics showed increased rates of 3-methylhistidine excretion as compared to six matched healthy subjects. Both treatments reduced urinary 3-methylhistidine to normal. During treatment, branched-chain amino acids failed to normalize, plasma aromatic amino acid concentrations and ammonia declined, and alanine increased. Branched-chain amino acids are mainly oxidized in skeletal muscle with production of alanine. Reduced muscle protein catabolism following amino acid infusion is consistent with the physiological role of branched-chain amino acids in suppressing protein breakdown and stimulating protein synthesis. Long-term therapy with branched-chain amino acid-enriched mixtures may prove useful in advanced cirrhotics with severe muscle wasting.