APOH Bovine

Overview of APOH Bovine

Apolipoprotein H (APOH) is a plasma protein with critical roles in coagulation regulation, lipid metabolism, and immune modulation. The bovine variant, APOH Bovine, is purified from fetal calf serum (FCS) and shares structural and functional homology with human APOH. It is commercially available as a recombinant protein or purified antigen, primarily used in biomedical research to study thrombosis, inflammation, and lipid-related diseases .

Molecular Structure and Properties

APOH Bovine is a glycosylated protein with a molecular weight of approximately 70 kDa (purified form) or 37.8 kDa (calculated from amino acid sequence) . Key features include:

• Four Sushi (CCP/SCR) domains: Enable binding to negatively charged molecules like phospholipids, heparin, and dextran sulfate .

• Signal peptide: 19-amino-acid sequence directing secretion .

• Mature protein: 326 amino acids in bovine APOH, showing 89% homology to human and 86% to rat APOH .

Functional Roles

APOH Bovine exhibits multifaceted biological activities:

1. Coagulation Regulation:

   • Binds to phospholipids on damaged cell membranes, preventing activation of the intrinsic coagulation cascade .

   • Acts as a cofactor for antiphospholipid autoantibodies in conditions like antiphospholipid syndrome (APS) .

2. Immune Modulation:

   • Inhibits M1 macrophage polarization by suppressing TLR4/NF-κB signaling, reducing pro-inflammatory cytokines (e.g., TNF-α, IL-6) and increasing anti-inflammatory IL-10 .

   • Neutralization of APOH exacerbates organ injury and mortality in sepsis models .

3. Lipid Metabolism:

   • Associates with lipoproteins, influencing triglyceride and cholesterol transport .

Research Applications

APOH Bovine is employed in diverse experimental contexts:

• Therapeutic Studies: Recombinant APOH administration in murine sepsis models reduced mortality, organ injury, and inflammation, highlighting potential therapeutic applications .

• Coagulation Pathway Analysis: Used to study antiphospholipid antibody interactions and thrombosis mechanisms .

• Lipoprotein Research: Investigates lipid metabolism and reverse cholesterol transport .

Key Research Findings

1. Sepsis Protection:

   • In murine models, recombinant APOH reduced mortality by 40–50% and mitigated lung/kidney injury .

   • Neutralizing APOH increased sepsis severity, underscoring its protective role .

2. Structural Insights:

   • Bovine APOH shares conserved Sushi domains with human APOH, enabling cross-species functional studies .

3. Clinical Relevance:

   • Low APOH levels correlate with poor outcomes in pediatric sepsis, suggesting biomarker potential .