Effects of vitamin D supplementation on alveolar macrophage gene expression: preliminary results of a randomized, controlled trial

  • Alicia K. Gerke | alicia-gerke@uiowa.edu Department of Internal Medicine, University of Iowa, Iowa City, IA, United States.
  • Alejandro A. Pezzulo Department of Internal Medicine, University of Iowa, Iowa City, IA, United States.
  • Fan Tang Department of Biostatistics, University of Iowa, Iowa City, IA, United States.
  • Joseph E. Cavanaugh Department of Biostatistics, University of Iowa, Iowa City, IA, United States.
  • Thomas B. Bair University of Iowa Institute for Human Genetics, Iowa City, IA, United States.
  • Emily Phillips Department of Internal Medicine, University of Iowa, Iowa City, IA, United States.
  • Linda S. Powers Department of Internal Medicine, University of Iowa, Iowa City, IA,, United States.
  • Martha M. Monick Department of Internal Medicine, University of Iowa, Iowa City, IA, United States.

Abstract

Background: Vitamin D deficiency has been implicated as a factor in a number of infectious and inflammatory lung diseases. In the lung, alveolar macrophages play a key role in inflammation and defense of infection, but there are little data exploring the immunomodulatory effects of vitamin D on innate lung immunity in humans. The objective of this study was to determine the effects of vitamin D supplementation on gene expression of alveolar macrophages.

Methods: We performed a parallel, double-blind, placebo-controlled, randomized trial to determine the effects of vitamin D on alveolar macrophage gene expression. Vitamin D3 (1000 international units/day) or placebo was administered to adults for three months. Bronchoscopy was performed pre- and post-intervention to obtain alveolar macrophages. Messenger RNA was isolated from the macrophages and subjected to whole genome exon array analysis. The primary outcome was differential gene expression of the alveolar macrophage in response to vitamin D supplementation. Specific genes underwent validation by polymerase chain reaction methods.

Results: Fifty-eight subjects were randomized to vitamin D (n = 28) or placebo (n = 30). There was a marginal overall difference between treatment group and placebo group in the change of 25-hydroxyvitaminD levels
(4.43 ng/ml vs. 0.2 ng/ml, p = 0.10). Whole genome exon array analysis revealed differential gene expression associated with change in serum vitamin D levels in the treated group. CCL8/MCP-2 was the top-regulated cytokine gene and was further validated.

Conclusions: Although only a non-significant increased trend was seen in serum vitamin D levels, subjects treated with vitamin D supplementation had immune-related differential gene expression in alveolar macrophages.

Trial registration: ClinicalTrials.org: NCT01967628.

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Published
2014-03-05
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Original Research Articles
Keywords:
Alveolar, Gene expression, Immunity, Innate, Macrophages, Randomized controlled, Vitamin D
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How to Cite
Gerke, A. K., Pezzulo, A. A., Tang, F., Cavanaugh, J. E., Bair, T. B., Phillips, E., Powers, L. S., & Monick, M. M. (2014). Effects of vitamin D supplementation on alveolar macrophage gene expression: preliminary results of a randomized, controlled trial. Multidisciplinary Respiratory Medicine, 9(1). https://doi.org/10.4081/mrm.2014.417