Vitamin D Supplementation Enhances Immune Response to Bacille-Calmette-Guerin (BCG) Vaccination in Infants (BCG-25-D)

Vitamin D Supplementation Enhances Immune Response to Bacille-Calmette-Guerin (BCG) Vaccination in Infants

The purpose of this study is to determine whether a single oral dose of vitamin D given to infants prior to Bacille-Calmette-Guerin (BCG) vaccination will enhance the immune response to BCG vaccination.

In 2000, there were an estimated 884,000 cases of tuberculosis (TB) in children with many developing severe, disseminated disease. Widespread immunization with Bacille-Calmette-Guerin (BCG) vaccine has not been effective in preventing primary TB infection or in halting the progression from latent to active disease. Poor vaccine efficacy has prompted investigators to develop novel TB vaccines and to experiment with enhancing the immune response to the current BCG vaccine. Increasing data indicate that children with low vitamin D levels and specific genetic variants that lower functional levels of vitamin D are at increased risk for severe tuberculosis. Elegant studies investigating Mycobacterium tuberculosis (Mtb) infection have shown that mycobacteria are able to reside in endosomes within macrophages by preventing endosome-lysosome fusion; a critical step in autophagy, a cellular process used to recycle cytoplasmic organelles and proteins, and to degrade microbial organisms including Mtb. In-vitro studies have shown that vitamin D increases autophagy and triggers the production of antimicrobial peptides including cathelicidin. This leads to increased intracellular killing of Mtb and increased Mtb antigen presentation to the immune system. Anti-tuberculous vaccines that over-express Mtb antigens generate a stronger immune response than wild type BCG vaccine. The investigators hypothesis is that a single oral dose of vitamin D3 (cholecalciferol) given to infants prior to BCG administration will enhance the immune response to vaccination through improved MHC class I and class II presentation of the vaccine.

A single oral dose of 50,000 IU of vitamin D3 (cholecalciferol) will be given prior to Bacille-Calmette-Guerin (BCG) vaccination

BCG vaccine efficacy will be assessed by measuring the host immune response against BCG at 2 months, 6 months and one year after BCG immunization. A whole blood assay will be used to measure multiple cytokines and mycobacterial growth suppression.

Serum 25 hydroxy (OH) vitamin D levels will be measured prior to vitamin D supplementation and at 2 months, 6 months and one year after BCG immunization. The investigators will also determine whether specific host genetic variants including the Fok-I(rs2228570T/C), Bsm-I(rs1544410A/G), GC(rs2282679A/C), DHCR7(rs12785878G/T) and CYP2R1 (rs10741657A/G) polymorphisms affect baseline vitamin D levels and alter the response to vitamin D supplementation.

The investigators will determine whether specific host genetic variants including the Fok-I(rs2228570T/C), Bsm-I(rs1544410A/G), GC(rs2282679A/C), DHCR7(rs12785878G/T) and CYP2R1 (rs10741657A/G) polymorphisms affect the response to BCG vaccine in infants receiving either vitamin D or placebo.

Inclusion Criteria: Healthy mothers > 18 years of age Term, healthy infants eligible to receive the Bacille-Calmette- Guerin (BCG) vaccine Exclusion Criteria: Recent maternal history of tuberculosis (within 1 year) or active tuberculosis Known maternal human immuno-deficiency virus (HIV) infection Maternal fever or chorio-amnionitis Maternal use of vitamin D, steroids or immuno-regulatory medications Household member with active tuberculosis

Huey SL, Acharya N, Silver A, Sheni R, Yu EA, Pena-Rosas JP, Mehta S. Effects of oral vitamin D supplementation on linear growth and other health outcomes among children under five years of age. Cochrane Database Syst Rev. 2020 Dec 8;12(12):CD012875. doi: 10.1002/14651858.CD012875.pub2.