Delinking CARD9 and IL-17: Protects against Candida tropicalis Infection through a TNF-α–Dependent, IL-17–Independent Mechanism

Natasha Whibley, Jillian R Jaycox, Delyth Reid, Abhishek V Garg, Julie A Taylor, Cornelius J Clancy, M Hong Nguyen, Partha S Biswas, Mandy J McGeachy, Gordon D Brown, Sarah L Gaffen

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)
6 Downloads (Pure)


Candida is the third most common cause of bloodstream infections in hospitalized patients. Immunity to C. albicans, the most frequent species to be isolated in candidiasis, involves a well-characterized Dectin-1/caspase-associated recruitment domain adaptor 9 (CARD9)/IL-17 signaling axis. Infections caused by non-albicans Candida species are on the rise, but surprisingly little is known about immunity to these pathogens. In this study, we evaluated a systemic infection model of C. tropicalis, a clinically relevant, but poorly understood, non-albicans Candida. Mice lacking CARD9 were profoundly susceptible to C. tropicalis, displaying elevated fungal burdens in visceral organs and increased mortality compared with wild-type (WT) controls. Unlike C. albicans, IL-17 responses were induced normally in CARD9(-/-) mice following C. tropicalis infection. Moreover, there was no difference in susceptibility to C. tropicalis infection between WT and IL-23p19(-/-), IL-17RA(-/-), or Act1(-/-) mice. However, TNF-α expression was markedly impaired in CARD9(-/-) mice. Consistently, WT mice depleted of TNF-α were more susceptible to C. tropicalis, and CARD9-deficient neutrophils and monocytes failed to produce TNF-α following stimulation with C. tropicalis Ags. Both neutrophils and monocytes were necessary for defense against C. tropicalis, because their depletion in WT mice enhanced susceptibility to C. tropicalis. Disease in CARD9(-/-) mice was not due to defective neutrophil or monocyte recruitment to infected kidneys. However, TNF-α treatment of neutrophils in vitro enhanced their ability to kill C. tropicalis. Thus, protection against systemic C. tropicalis infection requires CARD9 and TNF-α, but not IL-17, signaling. Moreover, CARD9-dependent production of TNF-α enhances the candidacidal capacity of neutrophils, limiting fungal disease during disseminated C. tropicalis infection.

Original languageEnglish
Pages (from-to)3781-3792
Number of pages12
JournalThe Journal of Immunology
Issue number8
Early online date2 Sept 2015
Publication statusPublished - Oct 2015

Bibliographical note

Copyright © 2015 The Authors.

We thank Genentech for IL-232/2 mice and Amgen for IL-17RA2/2 mice.
CARD92/2 mice were a kind gift from Dr. Xin Lin (MD Anderson Cancer
Center, Houston, TX). Act12/2 mice were generously provided by Dr.
U. Siebenlist (National Institutes of Health, Bethesda, MD). We thank
J.K. Kolls and A.P. Mitchell for valuable suggestions and critical reading.


Dive into the research topics of 'Delinking CARD9 and IL-17: Protects against Candida tropicalis Infection through a TNF-α–Dependent, IL-17–Independent Mechanism'. Together they form a unique fingerprint.

Cite this