Anti-inflammatory & Tissue-Penetrating Compounds

Hyaluronidase is an enzyme that cleaves hyaluronic acid in the extracellular matrix. This action serves two critical functions:

• Tissue permeability: Increases tissue permeability, allowing other salivary compounds (hirudin, calin, etc.) to penetrate deeper into tissue
• Anti-inflammatory: Modulates inflammation through HA fragment signaling (short HA fragments have distinct immunological properties from intact HA)

Molecular weight: ~28.5 kDa
Pharmaceutical use: Hyaluronidase is used clinically as a “spreading agent” (e.g., Hylenex) to enhance subcutaneous drug absorption.

Eglin c is a ~8 kDa protease inhibitor (potato inhibitor I family) that targets destructive neutrophil-derived proteases:

• Elastase — degrades elastin in connective tissue
• Cathepsin G — broad-spectrum serine protease
• Chymase — mast cell protease

Anti-inflammatory mechanism: By blocking neutrophil proteases at inflammation sites, eglin c prevents tissue destruction and modulates the inflammatory cascade.

Research status: Recombinant eglin c has been studied for treatment of sepsis and acute pancreatitis in preclinical models, though no clinical trials have progressed to approval.

Bdellins are two classes of protease inhibitors (bdellin A ~6 kDa, bdellin B ~7 kDa) that inhibit:

• Trypsin — pancreatic serine protease
• Plasmin — fibrinolytic enzyme
• Acrosin — sperm protease (involved in fertilization)

Bdellins serve both anti-inflammatory and antifibrinolytic roles. They work alongside eglin c to create comprehensive protease inhibition — preventing excessive inflammation while maintaining controlled fibrinolysis.

These compounds work together in a coordinated sequence:

1. Hyaluronidase opens tissue barriers → allows deeper penetration of anticoagulants
2. Eglin and bdellins suppress inflammation → prevents host immune response from disrupting feeding
3. Anticoagulants maintain blood flow → ensures continuous feeding and post-detachment bleeding

This is not a random cocktail — it is an evolutionarily optimized biochemical strategy for sustained blood feeding.