Effects of Short-Term Calcifediol Supplementation on Leukocyte Cytokine Production in Healthy Dogs: A Randomized, Double-Blinded, Placebo-Controlled Crossover Trial.

Abstract

BACKGROUND: Vitamin D modulates the immune response in many species, including dogs. To date, research investigating the immunological effects of vitamin D in dogs is limited to in&#xa0;vitro studies. OBJECTIVES: Provide PO calcifediol supplementation to healthy dogs to evaluate its tolerability and assess its effect on leukocyte production of tumor necrosis factor (TNF)-&#x3b1;, interleukin (IL)-6, and IL-10. ANIMALS: Eleven healthy client-owned dogs with serum 25-hydroxyvitamin-D(25(OH)D) concentrations &#x2264;&#x2009;30&#x2009;ng/mL. METHODS: Prospective, randomized, double-blinded, placebo-controlled crossover study. Dogs were randomized to receive calcifediol at 2.3&#x2009;&#x3bc;g/kg(low-dose), 4.6&#x2009;&#x3bc;g/kg(high-dose), or placebo for 7&#x2009;days and crossed over to a different treatment arm after 28-day washout periods. Serum 25(OH)Dwas measured using a modified high-performance liquid chromatography method. Whole blood cultures were performed by incubating blood with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or phosphate-buffered saline (PBS) for 24&#x2009;h, and TNF-&#x3b1;, IL-6, and IL-10 were measured in supernatant using a canine-specific multiplex assay. RESULTS: Both low-dose (median, interquartile range [IQR]; 62&#x2009;ng/mL, 59-82) and high-dose (93&#x2009;ng/mL, 80-113) PO calcifediol supplementation increased serum 25(OH)Dconcentrations from baseline (22.2&#x2009;ng/mL, 20.3-29.3; both p&#x2009;<&#x2009;0.0001). Low-dose and high-dose calcifediol supplementation decreased LPS-stimulated IL-6 by 197&#x2009;pg/mL (95% confidence interval [CI]: -369.0 to -24.0; p&#x2009;=&#x2009;0.03) and 182&#x2009;pg/mL (95% CI: -355.0 to -8.0; p&#x2009;=&#x2009;0.04), respectively. Then LPS-stimulated IL-6 concentrations decreased by 2&#x2009;pg/mL for every 1&#x2009;ng/mL increase in serum 25(OH)Dconcentration (95% CI: -3.0 to -0.1; p&#x2009;=&#x2009;0.03). CONCLUSION AND CLINICAL IMPORTANCE: Calcifediol supplementation for 7&#x2009;days was well-tolerated and decreased LPS-stimulated IL-6 concentrations. Oral calcifediol supplementation may have anti-inflammatory effects in dogs.