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Cytokines in stools of children with inflammatory bowel disease or infective diarrhoea
S Nicholls1, S Stephens, C P Braegger
1Department of Paediatric Gastroenterology, St Bartholomew's Hospital, London.
Insights
Tumour necrosis factor alpha (TNF alpha) is consistently found in healthy children's stools, while interleukin-6 (IL-6) is not. Elevated TNF alpha suggests inflammation, but stool IL-6 is unreliable due to rapid degradation.
Area of Science:
- Pediatric Gastroenterology
- Immunology
- Biomarker Research
Background:
- Interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF alpha) are key inflammatory cytokines.
- Assessing intestinal inflammation in children often involves stool sample analysis.
Purpose of the Study:
- To quantify IL-6 and TNF alpha levels in the stools of healthy children and those with inflammatory bowel disease (IBD) or acute diarrhea.
- To evaluate the utility of stool IL-6 and TNF alpha as biomarkers for pediatric intestinal inflammation.
Main Methods:
- Stool samples were collected from healthy children, children with IBD (active and inactive), and children with acute diarrhea.
- Cytokine concentrations were measured using enzyme-linked immunosorbent assay (ELISA).
- Analysis included assessment of potential factors affecting cytokine stability in stool.
Main Results:
- TNF alpha was detected in all healthy children's stools; IL-6 was rarely detected.
- Children with active IBD showed increased stool TNF alpha, but IL-6 remained largely undetectable.
- A heat-labile factor in stool rapidly degraded IL-6 immunoreactivity, limiting its usefulness.
- Children with Shigella flexneri infection exhibited very high levels of both TNF alpha and IL-6.
Conclusions:
- Constant, low-level TNF alpha production occurs in the healthy pediatric intestine.
- Elevated stool TNF alpha may indicate mucosal inflammation but lacks specificity.
- Stool IL-6 is an unreliable marker for assessing pediatric intestinal inflammation due to rapid loss of immunoreactivity.
Aims:
To determine the concentrations of interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF alpha) in stools from children.
Methods:
Stool samples from 14 healthy children, 32 children with inflammatory bowel disease, and 23 children with acute diarrhoea were emulsified in an equal volume of phosphate buffered saline and then centrifuged to produce a clear supernatant fluid. IL-6 and TNF alpha were measured by enzyme linked immunosorbent assay (ELISA).
Results:
TNF alpha was detected in the stools of all 14 healthy children (12-130 pg/g stool), but IL-6 was detected only in three. Similar results were seen in children with inactive inflammatory bowel disease. Stool TNF alpha concentrations were raised in samples from children with active inflammatory bowel disease, but in most (11/18) of these samples IL-6 was undetectable. Stool samples contained a heat-labile factor which rapidly destroyed IL-6 immunoreactivity. Most children with diarrhoea had TNF alpha concentrations similar to those of healthy controls and most were also negative for IL-6. Three children with Shigella flexneri infection had extraordinarily high concentrations of both TNF alpha and IL-6 in their stools.
Conclusions:
There is constant low grade production of TNF alpha in the intestine of healthy people. Raised values are indicative of mucosal inflammation, but are not specific. Stool IL-6 is of little use in assessing mucosal inflammation because immunoreactivity is rapidly lost in stool samples.