Evaluating Responses to Gluten Challenge: A Randomized, Double-Blind, 2-Dose Gluten Challenge Trial.

ABSTRACT BACKGROUND & AIMS Gluten challenge is used to diagnose celiac disease (CeD) and for clinical research. Sustained gluten exposure reliably induces histological changes but is burdensome. We investigated the relative abilities of multiple biomarkers to assess disease activity induced by two gluten doses, and aimed to identify biomarkers to supplement or replace histology. METHODS In this randomized, double-blind, 2-dose gluten-challenge trial conducted in two US centers (Boston, MA), 14 adults with biopsy-proven CeD were randomized to 3 g or 10 g gluten/day for 14 days. The study was powered to detect changes in villous height:crypt depth (Vh:Cd), and stopped at planned interim analysis on reaching this endpoint. Additional endpoints included gluten-specific cluster of differentiation (CD)4 T-cell analysis with human leukocyte antigen (HLA)-DQ2-gluten tetramers and enzyme-linked immune absorbent spot (ELISpot), gut-homing CD8 T cells, interleukin (IL)-2, symptoms, video capsule endoscopy (VCE), intraepithelial leukocytes (IELs), and tissue multiplex immunofluorescence. RESULTS All assessments showed changes with gluten challenge. However, time to maximal change, change magnitude, and gluten dose–response relationship varied. Vh:Cd, VCE enteropathy score, ELISpot, gut-homing CD8 T cells, IEL counts, and HLA-DQ2-restricted gluten-specific CD4 T cells showed significant changes from baseline only at 10 g gluten; symptoms were significant at 3 g. Symptoms and plasma IL-2 levels increased significantly or near significantly at both doses. IL-2 appeared to be the earliest, most sensitive marker of acute gluten exposure. CONCLUSIONS Modern biomarkers are sensitive and responsive to gluten exposure, potentially allowing less invasive, lower-dose, shorter-duration gluten ingestion. This work provides a preliminary framework for rational design of gluten challenge for CeD research.