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String test measures mucosal inflammation in eosinophilic esophagitis
Researchers developed an esophageal string test that can detect mucosal inflammation via proteins in the luminal secretions of children with eosinophilic esophagitis in a recent study.
The esophageal string test (EST) uses the Enterotest diagnostic device, which consists of a capsule containing 90 cm of string. Approximately 10 cm of string was pulled from the capsule, which participants swallowed, deploying the remaining string to the duodenal lumen, where samples of luminal secretions were collected. This test was performed in children with eosinophilic esophagitis (EoE) that was either active (n=14) or in remission (n=8), as well as children with GERD (n=4) and 15 controls. Investigators also performed esophageal mucosal biopsies, and eosinophil-derived proteins were measured from the EST and biopsy results.
“Children with EoE have undergone repeated endoscopies to assess for mucosal healing,” researchers Glenn T. Furuta, MD, director of the Gastrointestinal Eosinophilic Diseases Program at Children’s Hospital Colorado in Aurora, Colo., and Steven J. Ackerman, PhD, professor of biochemistry and molecular genetics at the University of Illinois at Chicago College of Medicine, told Healio.com. “While overall safe and an important analytical procedure, endoscopies are costly, time-consuming and do carry some risk. We sought to develop an alternative that would provide a method to assess patients’ inflammation in an outpatient office setting. … The EST may offer an attractive alternative to traditional endoscopy to monitor the success of therapeutic interventions in patients with EoE.”
The ESTs detected increases in eosinophil-derived proteins including MBP1, EPX, EDN and CLC/Gal-10. Test results indicated stronger concentrations of eosinophil-derived proteins among patients with active EoE compared with those with treated EoE in remission (P<.0001 for CLC/Gal-10; P<.001 for MBP1, and P<.01 for EPX), with GERD patients (P<.0001 for MBP1 and EDN, and P<.01 for CLC/Gal-10) and with patients without esophageal inflammation (P<.0001 for MBP1, EDN and CLC/Gal-10; P<.01 for ECP).
Investigators measured ROC curves for eosinophil-derived protein concentrations in ESTs and found C values of 0.97 for both MBP1 and CLC/Gal-10, 0.88 for EDN, 0.82 for EPX and 0.73 for ECP. ROC analysis for mucosal biopsy resulted in C values of 0.97 for MBP1, 0.99 for CLC/Gal-10 and EDN, 0.88 for EPX and 0.98 for ECP.
“We have demonstrated the use of a minimally invasive test, the EST, to document mucosal inflammation in children with EoE,” the researchers concluded. “Although we do not suggest that the EST will replace endoscopy and biopsy as a critical tool for analyses of EoE, it certainly has the potential to significantly improve the evaluation and treatment of patients with EoE who may require repeated assessments of their esophageal mucosae.”