Paediatric inflammatory bowel disease: a mechanistic approach to investigate exclusive enteral nutrition treatment

The inflammatory bowel diseases (IBD) include Crohn's disease (CD) and ulcerative colitis. The disease may present at any age although the peak of presentation is the second and third decades of life. The incidences of these diseases are increasing around the world with the age of presentation getting younger. At present CD is incurable with colectomy being the treatment for severe UC. Although several pharmacological approaches are used to modulate the inflammatory response in IBD, few lead to histological healing and most have side effects. An alternative approach is to use enteral formulae given exclusively (EEN) to treat IBD. EEN requires the consumption of an elemental or polymeric formula, with the exclusion of all other nutrients, for a period of up to 12 weeks. The introduction of EEN as a therapeutic option for IBD was through prudent observation; however, EEN has become an established and reliable option for the treatment of paediatric IBD. Despite this, the mechanisms through which EEN induces disease remission are unknown and remain hypothetical. This review will discuss recent research into EEN both describing clinical features of EEN therapy and discussing the most up-to-date understanding of the mechanisms through which EEN may be reducing intestinal inflammation and inducing disease remission.

Differential effects of nutritional and non-nutritional therapies on intestinal barrier function in an in vitro model

BACKGROUND

Diminished intestinal epithelial barrier function contributes to the pathogenesis of Crohn's disease. Clinical and experimental studies propose that increased tumor necrosis factor (TNF)-α promotes barrier dysfunction. The aim of this study was to investigate the effects of nutritional and other therapies upon intestinal barrier function in the presence of TNF-α in an in vitro model.

METHODS

Caco-2 monolayers were grown to confluence on membrane supports and then exposed to TNF-α in the presence of polymeric formula, hydrocortisone or infliximab. Monolayer permeability was evaluated by measuring epithelial resistance, short-circuit current and horseradish peroxidase flux in an Ussing chamber. Tight junction and myosin II regulatory light-chain kinase gene expression was analysed by real-time PCR, with protein expression and localization analysed by Western blot and immunofluorescence.

RESULTS

TNF-α increased monolayer permeability and diminished tight junction integrity. However both polymeric formula and infliximab completely abrogated the effects of TNF-α. These monolayers displayed unchanged permeability and tight junction integrity compared to untreated cells (media-no-TNF-α controls). In contrast, hydrocortisone only partially abrogated the effects of TNF-α, with these monolayers having increased permeability and altered tight junction integrity compared to media-no-TNF-α controls.

CONCLUSIONS

Both polymeric formula and infliximab completely prevent epithelial barrier dysfunction in the presence of TNF-α, whereas hydrocortisone partially prevents barrier dysfunction. These results provide evidence that superior mucosal healing can be achieved with both polymeric formula and infliximab compared to hydrocortisone.

Osteoprotegerin in pediatric Crohn's disease and the effects of exclusive enteral nutrition

BACKGROUND

Osteoprotegerin (OPG) may have proinflammatory roles in addition to its contribution to the maintenance of bone mass. Exclusive enteral nutrition (EEN) is an established therapy for the induction of remission in Crohn's disease (CD). The aims of this study were to ascertain serum, fecal, and mucosal expression of OPG in children with CD and to investigate the effects of EEN on OPG expression.

METHODS

OPG was measured by enzyme-linked immunosorbent assay in serum, mucosal, and fecal samples collected from children with CD and controls. Fecal and Serum OPG was measured prior to and following 6-8 weeks of EEN therapy.

RESULTS

Children with CD (n=82) and controls (n=45) were included. Mucosal and fecal OPG levels were elevated in CD compared to controls (P=0.018 and P<0.0001, respectively). Serum OPG was elevated in children with severe CD (P=0.005). Serum and fecal OPG levels dropped significantly following EEN therapy (P=0.0001 and P=0.002, respectively).

CONCLUSIONS

Increased serum and fecal OPG are seen in active CD and likely originate from the inflamed gut. Fecal and serum OPG decrease following EEN therapy. Further investigation of OPG and related proteins in the setting of IBD is now required.

Host attachment, invasion, and stimulation of proinflammatory cytokines by Campylobacter concisus and other non-Campylobacter jejuni Campylobacter species

BACKGROUND

Campylobacter concisus and other non-Campylobacter jejuni Campylobacter species have been implicated in the initiation of gastrointestinal diseases. In the present study, we investigated the interaction between these bacteria and the human intestinal epithelium and immune cells.

METHODS

The ability of C. concisus, Campylobacter showae, Campylobacter hominis, and Bacteroides ureolyticus to invade epithelial cells was examined using scanning electron microscopy and gentamicin protection assays. Proinflammatory cytokines generated by epithelial and immune cells in response to these bacteria were determined by enzyme-linked immunosorbent assay. Ussing Chamber, immunofluorescent stain, and Western blot were used to further elucidate the impact of C. concisus on intestinal barrier integrity and functions.

RESULTS

Attachment of non-C. jejuni Campylobacter species to Caco-2 or HT-29 cells was mediated by flagellum-dependent and/or -independent processes. C. concisus was able to invade Caco-2 cells, generate a membrane-ruffling effect on the epithelial surface on entry, and damage epithelial barrier functions by preferential attachment to the cell-cell junctions. Proinflammatory cytokine profiles exhibited by epithelial cells, monocytes, and macrophages in response to C. concisus and other non-C. jejuni Campylobacter species were species and strain specific.

CONCLUSIONS

These findings demonstrate that C. concisus and other non-C. jejuni Campylobacter species may play a role in initiating gastrointestinal diseases.

Development and assessment of a modified Pediatric Crohn Disease Activity Index

The Pediatric Crohn Disease Activity Index (PCDAI) is an established and validated measure of disease activity in children with Crohn disease. However, its use in the research setting can be limited because of ambiguity of the subjective and anthropometric components of the index. Here we propose and evaluate a modified PCDAI (Mod PCDAI) consisting of the laboratory measures of the PCDAI plus C-reactive protein. This Mod PCDAI can provide an indication of disease activity because it correlates with the PCDAI, physicians' global assessment, and fecal calprotectin, and therefore may provide a suitable alternative to the PCDAI when required.