Metabolomic basis for response to high dose vitamin D in critical illness

Abstract

Background & aims: It is unclear if intervention can mitigate the dramatic alterations of metabolic homeostasis present in critical illness. Our objective was to determine the associations between increased 25-hydroxyvitamin D levels following high dose vitamin D₃ and more favorable metabolomic profiles in critical illness.

Methods: We performed a post-hoc metabolomics study of the VITdAL-ICU randomized double-blind, placebo-controlled trial. Trial patients from Medical and Surgical Intensive Care Units at a tertiary university hospital with 25-hydroxyvitamin D level ≤20 ng/mL received either high dose oral vitamin D₃ (540,000 IU) or placebo. We performed an analysis of 578 metabolites from 1215 plasma samples from 428 subjects at randomization (day 0), day 3 and 7. Using mixed-effects modeling, we studied changes in metabolite profiles in subjects receiving intervention or placebo relative to absolute increases in 25-hydroxyvitamin D levels from day 0 to day 3.

Results: 55.2% of subjects randomized to high dose vitamin D₃ demonstrated an absolute increase in 25-hydroxyvitamin D ≥ 15 ng/ml from day 0 to day 3. With an absolute increase in 25-hydroxyvitamin D ≥ 15 ng/ml, multiple members of the sphingomyelin, plasmalogen, lysoplasmalogen and lysophospholipid metabolite classes had significantly positive Bonferroni corrected associations over time. Further, multiple representatives of the acylcarnitine and phosphatidylethanolamine metabolite classes had significantly negative Bonferroni corrected associations over time with an absolute increase in 25-hydroxyvitamin D ≥ 15 ng/ml. Changes in these highlighted metabolite classes were associated with decreased 28-day mortality.

Conclusions: Increases in 25-hydroxyvitamin D following vitamin D₃ intervention are associated with favorable changes in metabolites involved in endothelial protection, enhanced innate immunity and improved mitochondrial function.

Keywords: Acylcarnitine; Critical illness; Metabolomics; Phosphatidylethanolamine; Plasmalogen; Vitamin D.

Figure 1.

Circos plot of plasma metabolites by absolute increase in 25(OH)D levels. Bipartite graph illustrating mixed-effects linear regression results of metabolites with significantly changes (increased or decreased) over day 0, 3 and 7 with an absolute increase in 25(OH)D levels between day 0 and day 3. Graph connects metabolic response to an absolute increase in 25(OH)D levels with the individual metabolites grouped by metabolite Super Pathway (e.g. lipid) and Sub Pathway (e.g. sphingomyelin). Width of curves indicates strength of the significance (−log₁₀(p) value) with wider curves having greater significance. All metabolites shown are significant at the −log₁₀(p) > 4.06, p < 8.65 × 10⁻⁵ level.

Figure 2.

Rain plot of increasing metabolites by incremental absolute increase in 25(OH)D following intervention. The rain plot shows the directionality and magnitude of estimates of the association between individual metabolites and the absolute increase of plasma 25(OH)D between day 0 and day 3 to levels of ≥ 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 17.5 or 20.0 ng/ml. Results are focused on sphingomyelins, plasmalogens, lysoplasmalogen and lysophospholipids. The color fill scale of individual rain plots indicates the effect size - increased (dark red) or decreased (dark blue) of the individual metabolite following mixed-effects linear regression. The size of the individual rain ‘droplet’ indicates strength of the significance (−log₁₀(p) value) with larger plots having greater significance. Metabolites shown are considered significant at the −log₁₀(p) > 4.06, p < 8.65 × 10⁻⁵ level.

Figure 3.

Rain plot of decreasing metabolites by incremental absolute increase in 25(OH)D following intervention. The rain plot shows the directionality and magnitude of estimates of the association between individual metabolites and the absolute increase of plasma 25(OH)D between day 0 and day 3 to levels of ≥ 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 17.5 or 20.0 ng/ml. Results are focused on acylcarnitines and phosphatidylethanolamines. The color fill scale of individual rain plots indicates the effect size - increased (dark red) or decreased (dark blue) of the individual metabolite following mixed-effects linear regression. The size of the individual rain ‘droplet’ indicates strength of the significance (−log₁₀(p) value) with larger plots having greater significance. Metabolites shown are considered significant at the −log₁₀(p) > 4.06, p < 8.65 × 10⁻⁵ level.