Endothelial glycocalyx damage is associated with small intestinal disease in horses.

Overview

• This study investigated the relationship between endothelial glycocalyx damage and small intestinal disease in horses by measuring specific biomarkers in blood and peritoneal fluid.
• The goal was to determine if these biomarkers correlate with disease presence, type, and survival outcomes in equine small intestinal colic.

Background and Purpose

• The endothelial glycocalyx is a protective layer lining the blood vessels, composed of molecules such as syndecan-1, heparan sulfate, and hyaluronan.
• Damage to the glycocalyx can contribute to inflammation, vascular leakage, and tissue injury.
• Small intestinal diseases in horses, particularly inflammation and strangulating lesions, can result in severe colic and high mortality.
• The study aims to assess whether levels of glycocalyx components (syndecan-1, heparan sulfate, hyaluronan) in blood and peritoneal fluid are elevated in horses with intestinal disease compared to healthy horses, and if these levels relate to survival outcomes.

Study Design and Methods

• Sixty-one horses divided into three groups:
  • Control (healthy horses, n = 20)
  • Inflammatory small intestinal disease (n = 11)
  • Strangulating small intestinal lesions (n = 30)
• Paired blood and peritoneal fluid samples were collected from each horse between December 2016 and December 2024.
• Concentrations of syndecan-1, heparan sulfate, and hyaluronan were quantified using equine-specific ELISA assays.
• Patient survival until discharge was recorded to assess outcomes.
• Immunofluorescence staining was performed on jejunum tissue samples to visually evaluate heparan sulfate presence in healthy versus diseased intestines.

Key Findings

• Syndecan-1:
  • Levels were higher in horses with intestinal disease (both inflammatory and strangulating) compared to controls.
  • Elevated in peritoneal fluid of inflammatory cases versus controls.
  • Higher concentrations associated with horses that did not survive to discharge.
• Heparan Sulfate:
  • Increased levels detected in diseased horses compared to controls, especially in strangulating lesions.
  • Higher in nonsurviving horses.
  • Immunofluorescence showed a greater number of heparan sulfate-positive cells in diseased intestinal tissue, indicating glycocalyx damage.
• Hyaluronan:
  • Elevated in blood plasma in disease groups relative to controls.
  • Lower in peritoneal fluid of horses with strangulating lesions but higher overall in horses with intestinal disease.
  • Higher plasma levels correlated with nonsurvival.

Interpretation and Implications

• The increase in syndecan-1, heparan sulfate, and hyaluronan suggests that endothelial glycocalyx degradation occurs in horses with small intestinal disease.
• Higher levels of these biomarkers correlate with more severe disease and poorer outcomes, implying their potential utility as indicators of intestinal injury and prognostic markers.
• Immunofluorescence data support the biochemical findings by demonstrating the disruption of the glycocalyx in affected intestinal tissue.
• Measuring these biomarkers might provide a non-invasive method to assess the severity of intestinal damage and guide treatment decisions in horses with colic.

Conclusions and Future Directions

• Endothelial glycocalyx degradation is linked with small intestinal dysfunction and reduced survival in horses with colic.
• Further research is needed to validate these biomarkers as clinical tools for diagnosis, prognosis, and management of equine gastrointestinal diseases.
• Future studies may evaluate whether therapeutic interventions aimed at protecting or restoring the glycocalyx could improve outcomes in horses suffering from intestinal injury.