Candida and Complement: New Aspects in an Old Battle

Area of Science:

• Immunology
• Mycology
• Microbiology

Background:

• Candida species are opportunistic fungal pathogens, particularly in immunocompromised individuals.
• The complement system is crucial for immune defense against Candida, with evolving understanding of its role.
• Candida can act as a colonizer or a pathogen, with complex interactions at mucosal surfaces and in disseminated disease.

Purpose of the Study:

• To elucidate the molecular mechanisms of the Candida-complement system interplay.
• To investigate Candida's strategies for activating and evading the complement system.
• To explore the potential of targeting these interactions for novel antifungal therapies.

Main Methods:

• Analysis of Candida's direct and indirect activation of the three main complement pathways.
• Examination of complement-mediated anti-Candida effects like chemotaxis, opsonization, and phagocytosis.
• Investigation of Candida's evasion mechanisms, including protein cleavage and recruitment of regulatory proteins (e.g., factor H).

Main Results:

• Candida activates complement via direct and indirect pathways (coagulation/fibrinolysis).
• Complement enhances anti-Candida responses, but direct lysis is limited by the fungal cell wall.
• Candida employs evasion tactics like cleaving complement proteins and recruiting host regulators to dampen complement activity locally.
• Evasion mutant studies suggest in vivo complexity beyond initial hypotheses.

Conclusions:

• The Candida-complement interaction is a dynamic interplay involving activation and sophisticated evasion.
• Understanding these mechanisms, including against emerging threats like Candida auris, is vital for developing new antifungal strategies.
• Targeting the molecular interplay between Candida and the complement system offers a promising avenue for novel therapeutic interventions.