Circulating microRNAs as potential predictive biomarkers of equine metabolic syndrome.

Research Overview

• This study explores whether specific circulating microRNAs (miRNAs) in horse plasma can serve as early, non-invasive biomarkers to predict Equine Metabolic Syndrome (EMS), a disease linked to insulin dysregulation and laminitis risk.
• The research identifies four miRNAs with distinct expression patterns among EMS-affected horses, overweight/obese non-insulin dysregulated horses, and healthy controls, suggesting their potential diagnostic usefulness and roles in insulin-related pathways.

Background

• Equine Metabolic Syndrome (EMS): A complex endocrine disorder in horses characterized by insulin dysregulation (ID), increased fat accumulation, and a heightened risk of laminitis (a painful hoof disease).
• Challenges in EMS Diagnosis: Early and accurate diagnosis is difficult, which hampers timely intervention and management.
• MicroRNAs (miRNAs): Small, non-coding RNA molecules circulating in blood that regulate gene expression and are emerging as potential biomarkers for diseases in humans and animals.

Study Design

• Plasma samples were collected from three groups of horses:
  • EMS group (n=13) – horses diagnosed with Equine Metabolic Syndrome;
  • Overweight/Obese (OW/OB) non-ID group (n=16) – horses overweight/obese but without insulin dysregulation;
  • Healthy control group (n=16) – normal weight, metabolically healthy horses.
• A targeted OpenArray platform was used to profile circulating miRNAs in the plasma samples.
• Statistical analyses including Kruskal-Wallis tests with Dunn’s post hoc corrections were conducted to identify miRNAs differentially expressed between groups.

Key Findings

• Four miRNAs with significant differences in expression:
  • miR-221: Elevated in EMS horses compared to healthy controls (p=0.013).
  • miR-132: Elevated in OW/OB non-ID horses compared to both EMS and healthy horses (p=0.048 for both).
  • miR-186 and miR-15a: Higher expression in healthy controls compared to both EMS and OW/OB non-ID groups (miR-186 p=0.019 EMS vs healthy, p=0.001 OW/OB vs healthy; miR-15a p=0.032 EMS vs healthy, p=0.009 OW/OB vs healthy).
• Functional Enrichment Analysis: Predicted target genes of these miRNAs are involved in key insulin signalling pathways:
  • Phosphatidylinositol 3-kinase (PI3K)/Protein kinase B (AKT) pathway;
  • AMP-activated protein kinase (AMPK) pathway;
  • Forkhead box O protein (FOXO) signalling pathway.
• Diagnostic Potential: Receiver Operating Characteristic (ROC) curve analyses showed that combinations of these miRNAs could discriminate between clinical groups with strong accuracy (Area Under Curve or AUC values ranging from 0.79 to 0.93).

Significance and Implications

• Non-invasive Biomarkers: Circulating miRNAs present accessible, blood-based markers that could improve early detection and monitoring of EMS in horses.
• Mechanistic Insights: The involvement of miRNA target genes in critical insulin signalling pathways provides understanding of molecular mechanisms underlying EMS and points to possible therapeutic targets.
• Future Research Directions: These results establish a foundation for larger studies to validate these miRNAs as clinical biomarkers and investigate their functional roles, potentially leading to new interventions for EMS.

Summary

• This pilot study identifies four circulating miRNAs with distinct expression patterns in EMS, overweight/obese non-ID, and healthy horses.
• These miRNAs correlate with insulin signalling pathways and hold promise as predictive biomarkers for EMS development and progression.
• Overall, the study advances tools for non-invasive diagnosis and deepens understanding of EMS pathophysiology.