Inclusion Criteria - Challenge Study:  

• Males or females 18 to 70 years of age, inclusive.
• Subjects demonstrate willingness to participate in the study and to perform all required procedures as documented by signed informed consent.
• Subjects must have a diagnosis of celiac disease CeD by intestinal biopsy at least 12 months and positive celiac serology at some point in their evaluation, prior to screening as confirmed by medical records or written physician statement.
• Subjects must have reported following a strict GFD for at least the 12 consecutive months and must be willing to maintain their current diet for the duration of study participation while being in gluten challenge.
• Patients who don’t show mucosal healing with a VH:CD ratio < 2 at the baseline endoscopy will enter the GFD non-healed cohort (see below) and will not undergo gluten challenge.   Ninety percent of patients who are asymptomatic, adhere to GFD and are seronegative have achieved histologic healing.

Exclusion Criteria - Challenge Study:

• Current diagnosis of any severe complication of CeD, such as refractory CeD (RCD) type I or II, enteropathy-associated T-cell lymphoma (EATL), ulcerative jejunitis, or GI perforation.
• Diagnosis of any chronic, active GI disease other than CeD, such as active, untreated peptic ulcer, eosinophilic esophagitis, erosive esophagitis , ulcerative colitis or Crohn’s disease, microscopic colitis, irritable bowel syndrome, small intestinal bacterial overgrowth, tropical sprue, or other GI and non-GI disorder or prior GI surgery that may, in the Investigator’s opinion, interfere with the assessment of symptoms of abdominal pain, diarrhea, or other components of CeD.
• Selective IgA deficiency, defined as having undetectable levels of serum IgA.
• History of severe reaction to gluten exposure that is considered incapacitating or life-threatening.
• Known or suspected exposure to COVID-19 infection in the 4 weeks before the screening.
• History or presence of any clinically significant disease that, in the opinion of the Investigator may confound the subject’s participation and follow-up in the clinical trial or put the subject at unnecessary risk, including but not limited to: uncontrolled hypertension (BP ≥180/110 mm/Hg), unstable angina, Class II congestive heart failure or major fluid overload, coronary angioplasty or myocardial infarction within the past 6 months, clinically significant arrhythmias or electrocardiogram (ECG) abnormalities, severe chronic pulmonary disease, or any renal, hematologic, GI, immunologic, dermatologic, neurologic, or psychiatric disease.
• History of significant substance or alcohol abuse during the 12 months prior to screening as obtained by medical record and/or subject report.
• Females who are pregnant or planning to become pregnant during the study period, or who are currently breastfeeding.
• Participation in another investigational drug or device study or treatment with an investigational drug within 30 days or 5 half-lives, whichever is longer, prior to screening.
• Individuals with uncontrolled clotting disorders or on anti-coagulants that they can’t safely hold prior to endoscopy.
• Participation in clinical trial within 30 days prior to consenting, and 12 months for a clinical trial including a biologic agent.
• Participation in clinical trial with tolerogenic agents.

Inclusion Criteria - De-challenge Study:

• Males or females, 18 to 70 years of age, inclusive.
• Subjects demonstrate willingness to participate in the study and to perform all required procedures as documented by signed informed consent.
• Newly suspected subjects of CeD, either typical symptoms of CeD or referred to celiac clinic due to positive CeD serology undergoing upper endoscopy. Patients with weak positive serology will not be included in order to maximize the likelihood of the patients qualifying for the dechallenge study.    
• Subjects who are currently not on GFD.

Exclusion Criteria - De-challenge Study:

• Has a history of chronic inflammatory gastrointestinal disease (example, inflammatory bowel disease, extensive colitis, ulcerative jejunitis, drug induced enteropathy) (Microscopic colitis is not an exclusion criteria).
• Has chronic infectious gastrointestinal illness, or acute infectious gastrointestinal illness within the 4-week period prior to screening.
• Known history of lymphoproliferative disease, including monoclonal gammopathy of unknown significance, lymphoma, or signs and symptoms suggestive of possible lymphoproliferative disease, such as lymphadenopathy and/or splenomegaly.
• Individuals with uncontrolled clotting disorders or on anti-coagulants that they can’t safely hold prior to endoscopy.
• Known or suspected exposure to COVID-19 infection in the 4 weeks before the screening.
• History or presence of any clinically significant disease that, in the opinion of the Investigator may confound the subject’s participation and follow-up in the clinical trial or put the subject at unnecessary risk, including but not limited to: uncontrolled hypertension, unstable angina, Class II congestive heart failure or major fluid overload, coronary angioplasty or myocardial infarction within the past 6 months, clinically significant arrhythmias or ECG abnormalities, severe chronic pulmonary disease, or any renal, hematologic, GI, immunologic, dermatologic, neurologic, or psychiatric disease.
• History of significant substance or alcohol abuse during the 12 months prior to screening as obtained by medical record and/or subject report.
• Participation in another investigational drug or device study or treatment with an investigational drug within 30 days or 5 half-lives, whichever is longer, prior to screening.
• Participation in clinical trial within 30 days prior to consenting, and 12 months for a clinical trial including a biologic agent.
• Participation in clinical trial with tolerogenic agents
• Participants whose initial biopsies do not reveal villous atrophy will not be followed in the de-challenge group but may be recruited into the potential celiac disease cross sectional group so long as they meet the criteria for inclusion into that group.

Inclusion Criteria - Controls:

• Subjects (both cases and controls) will include males and non-pregnant females, aged 18-70 years.
• Females of reproductive age or capacity (i.e. not having had tubal ligation or sterilization) will have a pregnancy test performed.

Exclusion Criteria - Controls:

• Subjects on antibiotics, proton pump inhibitors, aspirin, non-steroidal anti-inflammatory drugs, alcohol intake within 48 hours, a bowel preparation within 4 weeks of the studies, and smokers
• Subjects will be asked not to take any probiotics in the week before testing.
• Any known intestinal inflammation such as GERD, eosinophilic esophagitis, and inflammatory bowel disease.
• Prior gastrointestinal surgery (other than appendectomy)
• Ongoing use of antiplatelet agents or anticoagulants.
• Controls should not have a prior history of or family history of CD.
• Subjects unable to provide informed consent
• The presence of any medical or psychological condition could interfere with the safe performance of the upper endoscopy.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 9/19/23. Questions regarding updates should be directed to the study team contact.