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Fungal pathogen recognition by scavenger receptors in nematodes and mammals
1Center for Immunology and Inflammatory Diseases and Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA. tmeans@partners.org
Abstract:
Macrophages are important cells in the host resistance to fungal infections, and fungal recognition by macrophages triggers phagocytosis, intracellular killing, induction of inflammatory cytokines and chemokines, and initiation of the adaptive immune response. All of the receptors that mediate binding and engulfment of fungal pathogens and the signaling pathways triggered by fungal pathogens that regulate anti-fungal immunity are not fully understood. Using an RNAi screen we recently demonstrated that the C. elegans receptors CED-1 and C03F11.3, and their mammalian orthologues, the scavenger receptors SCARF1 and CD36 mediate host defense against the fungal pathogen, Cryptococcus neoformans. Finally, SCARF1 and CD36 function as co-receptors by binding and engulfing fungal pathogens to facilitate Toll-like receptor 2 signaling. Here we will summarize and expand upon our previous findings.
Insights
Scavenger receptors SCARF1 and CD36 are crucial for host defense against fungal infections. These receptors mediate fungal pathogen engulfment and enhance Toll-like receptor 2 signaling for immunity.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Macrophages are key immune cells for fungal infection resistance.
- Fungal recognition by macrophages initiates phagocytosis, cytokine release, and adaptive immunity.
- The full spectrum of fungal recognition receptors and signaling pathways remains incompletely understood.
Purpose of the Study:
- To identify and characterize receptors involved in host defense against fungal pathogens.
- To elucidate the role of specific scavenger receptors in anti-fungal immunity.
- To expand upon previous findings regarding SCARF1 and CD36 in Cryptococcus neoformans infection.
Main Methods:
- RNA interference (RNAi) screen in C. elegans.
- Identification of conserved receptors mediating fungal pathogen defense.
- Analysis of mammalian orthologues SCARF1 and CD36.
- Investigation of their role in Cryptococcus neoformans interaction.
Main Results:
- The C. elegans receptors CED-1 and C03F11.3 were identified as important for fungal defense.
- Mammalian orthologues, scavenger receptors SCARF1 and CD36, were found to mediate host defense against Cryptococcus neoformans.
- SCARF1 and CD36 act as co-receptors, facilitating fungal pathogen engulfment and Toll-like receptor 2 signaling.
Conclusions:
- SCARF1 and CD36 are critical components of the innate immune system's response to fungal infections.
- These scavenger receptors play a dual role in pathogen recognition and signal transduction.
- Understanding these mechanisms can inform strategies to combat fungal diseases.
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