Serum proteomic analysis in equine obstructive colic: A prospective observational study.

Overview

• This study analyzed changes in serum proteins in horses suffering from obstructive intestinal colic to better understand disease mechanisms and to identify early diagnostic biomarkers.
• The researchers compared blood samples collected at the time of hospital admission and after recovery following conservative therapy, focusing on proteomic and biochemical changes.

Background and Objectives

• Obstructive colic in horses, a blockage of the intestines, is a serious condition that requires prompt diagnosis and treatment.
• The study aimed to identify specific protein patterns (proteomic signatures) in the blood serum that reflect pathological changes during colic.
• Researchers sought to find potential biomarkers that could help diagnose obstructive colic early and track recovery by assessing changes in protein expression.

Study Design and Methods

• Seven horses with simple obstructive intestinal colic were enrolled in a prospective observational study.
• Venous blood samples were collected from each horse twice: once at initial clinical examination (admission) and once after conservative treatment when the horse showed recovery (discharge).
• Standard hematological, biochemical, inflammatory, and lipid profiles were measured to evaluate overall health and metabolic states.
• Proteomic profiling was performed on all serum samples to identify differences in protein expression within the group (comparing sick horses at admission versus at discharge).
• A validation step for the most relevant proteins was conducted using Multiple Reaction Monitoring (MRM), a targeted mass spectrometry technique to quantify protein levels accurately.

Key Findings

• A total of 70 proteins showed significant changes in expression levels between admission and discharge states.
• Proteins related to the immune response demonstrated altered levels, suggesting activation or suppression of immune mechanisms during illness and recovery:
  • Complement component 2 (C2): Fold change (FC) +2.41 (increased)
  • Complement factor B (CFB): FC +3.41 (increased)
  • Hemopexin (HPX): FC +7.36 (increased)
  • Lactoferrin (LTF): FC -0.55 (decreased)
  • Proteasome subunit alpha type-7 (PSMA7): FC -0.55 (decreased)
• Proteins involved in blood coagulation pathways changed significantly, indicating possible alterations in clotting or vascular responses:
  • Von Willebrand factor (VWF): FC -0.54 (decreased)
  • Coagulation factor XIII subunits A1 (F13A1) and B (F13B): FCs around -0.54 to -0.57 (decreased)
  • Peroxiredoxin 2 (PRDX2): FC -0.41 (decreased)
  • Fibulin-1 (FBLN1): FC -0.62 (decreased)
  • Kininogen-1 (KNG1): FC -3.86 (strongly decreased)
• Proteins related to lipid metabolism and homeostasis were also significantly altered, reflecting metabolic disruptions in affected horses:
  • Apolipoproteins A4 (APOA4), A5 (APOA5), and E (APOE): FCs between -0.13 and -0.66 (decreased)
  • Lecithin-cholesterol acyltransferase (LCAT): FC -0.58 (decreased)

Interpretation and Implications

• The increased immune-related proteins suggest an inflammatory response potentially triggered by intestinal bacteria that may translocate during obstruction.
• Changes in coagulation-related proteins might reflect vascular or endothelial dysfunction occurring during colic.
• Alterations in lipid-related proteins indicate hyperlipidemia or disturbances in lipid metabolism potentially associated with the illness or stress response.
• The identified proteins could serve as potential biomarkers for early diagnosis as well as monitoring treatment response in equine obstructive colic.
• Understanding these proteomic changes provides insight into the pathophysiological processes underlying obstructive colic and supports development of improved clinical interventions.

Conclusion

• This study highlights the complex interplay of immune activation, coagulation disruption, and lipid metabolism imbalance in horses with obstructive intestinal colic.
• Serum proteomic analysis proved valuable in characterizing disease-associated changes and identifying candidate biomarkers that could aid early diagnosis and monitoring.
• Further studies with larger sample sizes and additional validation are warranted to refine these findings and translate them into practical veterinary diagnostic tools.