Hemocyanins: Microscopic Giants with Unique Structural Features for Applications in Biomedicine.

Area of Science:

• Immunology and Vaccinology
• Biochemistry and Structural Biology

Background:

• Limited availability and poor characterization of current vaccine adjuvants necessitate novel molecules.
• Hemocyanins, metalloglycoproteins from mollusks, possess potent immunomodulatory properties.
• Existing hemocyanins like Keyhole limpet hemocyanin (KLH) are used in research but face production challenges.

Purpose of the Study:

• To review the current understanding of hemocyanin structure and function as immunomodulators.
• To highlight the potential of hemocyanins as protein-based adjuvants (PBAs) for vaccines and immunotherapies.
• To discuss challenges and future directions for hemocyanin-based biomedical applications.

Main Methods:

• Review of existing literature on hemocyanin structure, immunomodulatory mechanisms, and applications.
• Analysis of hemocyanin interactions with innate immune receptors (C-type lectins, TLR4) and adaptive immune pathways (MHC-I, MHC-II).
• Evaluation of various gastropod hemocyanins (KLH, CCH, FLH, RvH, HpH) for their adjuvant potential.

Main Results:

• Hemocyanins activate MyD88- and TRIF-dependent pathways via mannose-rich N-glycans, promoting Th1-skewed responses.
• Conformational stability allows dual MHC-II and MHC-I routing, enhancing both CD4+ and CD8+ T-cell responses.
• Several hemocyanins demonstrate strong immunomodulatory effects, indicating potential as vaccine adjuvants and in cancer immunotherapy.

Conclusions:

• Hemocyanins are versatile natural immunomodulators with significant potential as protein-based adjuvants.
• Structural complexity hinders recombinant production, necessitating research into minimal adjuvant-active peptides.
• Advances in structural biology, immunology, and machine learning are crucial for developing reproducible hemocyanin-based therapeutics.