Longitudinal Evaluation of Vitamin D, Parathyroid Hormone, Antimicrobial Peptides, and Immunomodulatory Genes in Hospitalized Foals.
Authors: Kamr Ahmed M, Bartish Celine, Summers Jamie, Horton Julia, Hostnik Laura D, Orr Kindra, Browne Nimet, Dembek Katarzyna A, Saliba Caroline, Gomez Diego E, Toribio Ramiro E
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Vitamin D Status and Immune Function in Hospitalised Foals Vitamin D deficiency in hospitalised neonatal foals appears linked to compromised antimicrobial defences and worse clinical outcomes, yet this relationship has received little research attention in equine medicine. In a longitudinal study of 109 foals aged ≤72 hours (83 hospitalised—comprising 60 septic and 23 sick non-septic—versus 26 healthy controls), researchers tracked serum vitamin D metabolites, vitamin D binding protein, parathyroid hormone, and antimicrobial peptides (β-defensin-1 and cathelicidin-1) alongside gene expression markers over 72 hours of hospitalisation. Hospitalised foals demonstrated significantly lower concentrations of 25-hydroxyvitamin D, active 1,25-dihydroxyvitamin D, binding protein, and both antimicrobial peptides, whilst parathyroid hormone was elevated; septic foals specifically exhibited suppressed vitamin D receptor and CYP27B1 (the enzyme activating vitamin D) expression alongside heightened inflammatory markers including toll-like receptor-4, TNF-α, and IL-1β. Most critically, lower 25-hydroxyvitamin D, reduced antimicrobial peptide concentrations, and elevated parathyroid hormone independently associated with increased mortality risk in hospitalised foals. These findings suggest vitamin D plays a substantial immunomodulatory role in neonatal foals, potentially influencing both antimicrobial peptide production and inflammatory control—implications worth considering when managing sepsis risk and treatment outcomes in compromised newborns.
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Practical Takeaways
- •Monitor vitamin D status in hospitalized neonatal foals, particularly septic cases, as hypovitaminosis D is associated with increased mortality risk and warrants consideration for therapeutic supplementation
- •Low antimicrobial peptide concentrations in hospitalized foals reflect impaired innate immunity; vitamin D status assessment could inform clinical prognosis and guide supportive care intensity
- •Consider vitamin D supplementation protocols for at-risk neonatal foals, as optimization of vitamin D metabolite concentrations may enhance antimicrobial peptide production and immune function
Key Findings
- •Hospitalized foals had significantly lower serum 25(OH)D, 1,25(OH)2D, DBP, β-defensin-1, and cathelicidin-1 concentrations, with higher PTH concentrations compared to healthy foals (p<0.05)
- •Septic foals demonstrated lower VDR and CYP27B1 mRNA expression but higher TLR-4, TNF-α, and IL-1β mRNA expression than healthy foals (p<0.05)
- •Decreased serum 25(OH)D, β-defensin-1, cathelicidin-1, and elevated PTH concentrations were independently associated with higher odds of mortality in hospitalized foals (p<0.05)
- •Vitamin D metabolite deficiency correlates with reduced antimicrobial peptide production, suggesting vitamin D plays critical immunomodulatory roles in neonatal foal immunity