Vitamin D Regulation of Gut Specific B Cells and Antibodies Targeting Gut Bacteria in Inflammatory Bowel Disease

Vitamin D Regulation of α4β7+ B Cell Immunophenotypes and Mucosal Antibody Response to Commensal Gut Bacteria in Patients With Inflammatory Bowel Disease

Specific Aim 1: Characterize the effects of vitamin D treatment on expression of α4β7 on B cells in patients with inflammatory bowel disease (IBD).

Specific Aim 2: Determine the effects of vitamin D treatment on fecal immunoglobulins, percentage of Ig-coated gut bacteria, gut microbiome composition (global and bound by immunoglobulins) in patients with IBD and the association of these parameters with change in α4β7+ B cells .

Specific Aim 3: Compare BCR repertoire (BCR clonotypes, immunoglobulin heavy chain gene (IGHV), and isotype usage) between α4β7+ and α4β7- B cells in patients with IBD and identify α4β7+ BCR clonotypes associated with Ig-bound gut bacteria .

Inclusion Criteria:

• Adult patients (18 years or older) with inflammatory bowel disease (ulcerative colitis or Crohn's disease)
• Low serum vitamin D (25(OH)D ≤ 25 ng/mL
• Not currently on high dose vitamin D supplementation
• No prior bowel resections
• No antibiotic use in past 3 months.

Exclusion Criteria:

• Patients less than 18 years old
• No diagnosis of IBD
• Serum 25(OH)D > 25 ng/mL
• Patients already on vitamin D supplementation
• Prior history of bowel surgery (colectomy or small bowel resections)
• Recent antibiotic use in past 3 months
• Renal Dysfunction
• History of Hypercalcemia
• History of HIV
• History of IgA deficiency
• History of Common Variable Immunodeficiency (CVID)
• Active C. diff infection