Caspofungin-mediated beta-glucan unmasking and enhancement of human polymorphonuclear neutrophil activity against Aspergillus and non-Aspergillus hyphae.

Background: We investigated whether caspofungin and other echinocandins have immune-enhancing properties that influence human polymorphonuclear neutrophil (PMN)-mediated mold hyphal damage.

Materials And Methods: Using aniline blue staining, we compared patterns of beta-glucan exposure in Aspergillus fumigatus, Aspergillus terreus, Rhizopus oryzae, Fusarium solani, Fusarium oxysporum, Scedosporium prolificans, and Scedosporium apiospermum hyphae after caspofungin exposure. We also determined PMN-mediated hyphal damage occurring with or without preexposure to caspofungin or with preexposure to the combination of caspofungin and anti-beta-glucan monoclonal antibody, using 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-sH-tetrazolium hydroxide (XTT) assay.

Results: Preincubation with caspofungin (32 microg/mL for R. oryzae; 0.0625 microg/mL for other isolates) increased exposure to beta-glucan. PMN-induced damage increased after caspofungin exposure and was further augmented by the addition of anti-beta-glucan antibody. Preincubation with micafungin or anidulafungin had similar effects on PMN-induced damage of A. fumigatus hyphae. Finally, preexposure of A. fumigatus, but not S. prolificans, to caspofungin induced expression of Dectin-1 by PMN.

Conclusions: The results of the present study suggest inducement of beta-glucan unmasking by echinocandins and enhancement of PMN activity against mold hyphae, thereby supporting the immunopharmacologic mode of action of echinocandins.