434 Salivary Proteins — Integrated Proteomics of Hirudo medicinalis

For over a century, our understanding of leech SGSry composition was limited to approximately 20 compounds isolated through classical biochemistry — hirudin, calin, destabilase, hyaluronidase, bdellins, and eglins being the best characterized. Liu et al. (2019) transformed this picture using integrated proteomics and transcriptomics, revealing that the medicinal leech secretome is vastly more complex than previously understood.[R1]

The study combined two complementary omics approaches:

The 434 identified proteins were classified into six major functional groups, revealing the multi-target nature of leech SGS:

The Liu et al. study fundamentally changed our understanding of how leech therapy works. Instead of a simple anticoagulant effect (the hirudin-centric model), we now understand that the leech delivers a coordinated multi-target pharmacological cocktail — simultaneously acting on coagulation, platelets, vasculature, inflammation, pain, and infection. This multi-target mechanism may explain the broad therapeutic effects observed clinically, including the prolonged pain relief seen in osteoarthritis trials.[R1]

The dataset also provides a rich source for drug discovery: the vast majority of the 434 proteins remain uncharacterized for therapeutic potential, representing a largely untapped pharmacological resource.[R2][R3]