Characterization of antifungal C-type lectin receptor expression on murine epithelial and endothelial cells in mucosal tissues.

Our data reveal that selection of enzymes for generating single cell suspensions from murine tissues influences detection of surface expression of antifungal CLRs. Using a method that most preserves receptor expression, we show that non-myeloid expression of antifungal CLRs is limited to MelLec on endothelial cells in murine mucosal tissues.

Synthesis of the Fungal Metabolite YWA1 and Related Constructs as Tools to Study MelLec-Mediated Immune Response to Aspergillus Infections†.

We describe the chemical synthesis of the fungal naphthopyrones YWA1 and fonsecin B, as well as their functionalization with an amine-spacer arm and the conjugation of the resulting molecules to three different functional tags (i.e., biotin, Oregon green, 1-[3-(succinimidyloxycarbonyl)benzyl]-4-[5-(4-methoxyphenyl)-2-oxazolyl]pyridinium bromide (PyMPO)). The naphthopyrone-biotin and -PyMPO constructs maintained the ability to bind the C-type lectin receptor MelLec, whose interaction with immunologically active fungal metabolites (i.e., 1,8-dihydroxynaphthalene-(DHN)-melanin and YWA1) is a key step in host recognition and induction of protective immune responses against Aspergillus fumigatus. The fluorescent Fonsecin B-PyMPO construct 21 was used to selectively visualize MelLec-expressing cells, thus validating the potential of this strategy for studying the role and functions of MelLec in immunity.

C-Type Lectin Receptors in Antifungal Immunity.

Most fungal species are harmless to humans and some exist as commensals on mucocutaneous surfaces. Yet many fungi are opportunistic pathogens, causing life-threatening invasive infections when the immune system becomes compromised. The fungal cell wall contains conserved pathogen-associated molecular patterns (PAMPs), which allow the immune system to distinguish between self (endogenous molecular patterns) and foreign material. Sensing of invasive microbial pathogens is achieved through recognition of PAMPs by pattern recognition receptors (PRRs). One of the predominant fungal-sensing PRRs is the C-type lectin receptor (CLR) family. These receptors bind to structures present on the fungal cell wall, eliciting various innate immune responses as well as shaping adaptive immunity. In this chapter, we specifically focus on the four major human fungal pathogens, Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans and Pneumocystis jirovecii, reviewing our current understanding of the CLRs that are involved in their recognition and protection of the host.