Caspofungin‐Mediated β‐Glucan Unmasking and Enhancement of Human Polymorphonuclear Neutrophil Activity againstAspergillusand Non‐AspergillusHyphae

Abstract

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 β-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-β-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 µg/mL for R. oryzae; 0.0625 µg/mL for other isolates) increased exposure to β-glucan. PMN-induced damage increased after caspofungin exposure and was further augmented by the addition of anti-β-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 β-glucan unmasking by echinocandins and enhancement of PMN activity against mold hyphae, thereby supporting the immunopharmacologic mode of action of echinocandins.