Proteomic Profiling and Targeted Validation Reveal a More Extensive Salivary than Serum Response to a Feed-Deprivation Protocol in Horses with Gastric Lesions.

Overview

• This study investigated changes in protein levels in saliva and serum of horses subjected to a feed-deprivation protocol to better understand biomarkers related to gastric lesions.
• The research found that saliva exhibited a broader range of protein changes compared to serum, highlighting saliva’s potential as a useful non-invasive diagnostic fluid for gastric ulcers in horses.

Background and Purpose

• Gastric ulcers are common in horses but diagnosing them typically requires gastroscopy, an invasive procedure.
• The study aimed to explore whether protein changes in saliva and serum could serve as biomarkers related to feed deprivation-induced gastric lesions.
• Understanding these protein changes could improve diagnosis and monitoring of gastric ulceration using non-invasive methods.

Methodology

• Subjects: Eight horses were subjected to a controlled feed-deprivation protocol designed to induce gastric lesions.
• Gastric lesions were assessed via gastroscopy at the end of the protocol to confirm ulcer presence.
• Sample Collection:
  • Saliva and blood samples were collected both before (pre-protocol) and after (post-protocol) the feed deprivation.
• Analysis:
  • Pooled saliva and serum samples for each condition were analyzed using two-dimensional gel electrophoresis to identify differences in protein profiles.
  • Mass spectrometry was employed to identify the proteins with differential abundance between pre- and post-protocol states.
  • Western blotting was used for targeted validation of nine selected proteins in individual samples, confirming the changes observed in the proteomic analysis.

Key Findings

• Proteomic Differences:
  • 15 proteins in saliva and 5 proteins in serum exhibited significant changes following the feed-deprivation protocol.
• Validated Proteins:
  • The nine proteins validated play roles in various biological pathways:
    • Inflammatory and immune response: interleukin 1-F5, interleukin 1-F6, prolactin-inducible protein, alpha-1-antitrypsin.
    • Metabolic and transport processes: albumin, serotransferrin, apolipoprotein A-IV, fatty acid-binding protein 5.
    • Mucosal protection mechanisms: carbonic anhydrase VI, apolipoprotein A-IV, prolactin-inducible protein, fatty acid-binding protein 5.
• Saliva vs Serum:
  • Saliva showed a more dynamic and extensive proteomic response to feed deprivation, with more proteins displaying altered abundance.
  • This supports saliva as a versatile, non-invasive fluid for monitoring physiological changes linked to gastric lesions.

Implications and Conclusions

• The study provides a detailed characterization of protein changes in both saliva and serum associated with feed deprivation-induced gastric lesions in horses.
• The identification and validation of specific proteins involved in immune, metabolic, and mucosal protection pathways enhance understanding of the physiological response to gastric ulceration.
• Importantly, the broader and more pronounced changes in salivary proteins support its use as a practical, non-invasive diagnostic medium.
• These findings could guide development of salivary biomarker panels to improve diagnosis and monitoring of gastric ulcers in equine veterinary practice without relying solely on gastroscopy.