Gut Online First, published on August 15, 2012 as 10.1136/gutjnl-2012-303171 Furuta GT et al. “The oesophageal string test: a novel, minimally invasive method measures mucosal inflammation in eosinophilic oesophagitis”
This study examined an esophageal string test (EST) in 41 children; 14 with active EoE, 8 with EoE remission, 4 with gastroesophageal reflux, and 15 controls. The goal of this study was to measure eosinophil-derived proteins with an EST with a hypothesis that these proteins would correlate with mucosal inflammation as determined by biopsies.
Methods: Using a FDA approved device, Enterotest, patients were instructed to swallow a capsule attached to a string. Luminal secretion samples from the string were used for the EST. The esophageal portions of the string were aided by the use of pH indicator sticks. Patients were between 7 and 20 years of age. The EST was placed overnight in the esophagus. The EST was removed at the time of an endoscopy the following day.
The measured proteins included the following:
- Eosinophil secondary granule proteins: major basic protein-1(MBP-1), eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), and eosinophilic peroxidase (EPX).
- Charcot-Leyden crystal protein/galectin-10 (CLC/Gal-10)
When looking at Figure 1 in the results (full text link below), there is a striking difference in the measurement of these EoE proteins in the active group compared with the other groups. The remission EoE group also had modest elevation of EoE proteins, particularly ECP and EDN, relative to the GERD and control groups.
- Measurement of these proteins did correlate with peak and mean eosinophil counts and distinguished active EoE from the other groups
- EST could serve as a minimally invasive marker of for EoE activity and response to therapy. EST would be less expensive, quicker and safer than endoscopy
Technical issues will need to be addressed to improve the applicability of EST. For example, shorter incubation time could make the test more feasible. Also, for younger patients, swallowing an EST/capsule will remain problematic.
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