Human Dectin-1 deficiency impairs macrophage-mediated defense against phaeohyphomycosis
Rebecca A. Drummond, et al.
Rebecca A. Drummond, et al.
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Research Article Immunology Infectious disease

Human Dectin-1 deficiency impairs macrophage-mediated defense against phaeohyphomycosis

Abstract

Subcutaneous phaeohyphomycosis typically affects immunocompetent individuals following traumatic inoculation. Severe or disseminated infection can occur in CARD9 deficiency or after transplantation, but the mechanisms protecting against phaeohyphomycosis remain unclear. We evaluated a patient with progressive, refractory Corynespora cassiicola phaeohyphomycosis and found that he carried biallelic deleterious mutations in CLEC7A encoding the CARD9-coupled, β-glucan–binding receptor, Dectin-1. The patient’s PBMCs failed to produce TNF-α and IL-1β in response to β-glucan and/or C. cassiicola. To confirm the cellular and molecular requirements for immunity against C. cassiicola, we developed a mouse model of this infection. Mouse macrophages required Dectin-1 and CARD9 for IL-1β and TNF-α production, which enhanced fungal killing in an interdependent manner. Deficiency of either Dectin-1 or CARD9 was associated with more severe fungal disease, recapitulating the human observation. Because these data implicated impaired Dectin-1 responses in susceptibility to phaeohyphomycosis, we evaluated 17 additional unrelated patients with severe forms of the infection. We found that 12 out of 17 carried deleterious CLEC7A mutations associated with an altered Dectin-1 extracellular C-terminal domain and impaired Dectin-1–dependent cytokine production. Thus, we show that Dectin-1 and CARD9 promote protective TNF-α– and IL-1β–mediated macrophage defense against C. cassiicola. More broadly, we demonstrate that human Dectin-1 deficiency may contribute to susceptibility to severe phaeohyphomycosis by certain dematiaceous fungi.

Authors

Rebecca A. Drummond, Jigar V. Desai, Amy P. Hsu, Vasileios Oikonomou, Donald C. Vinh, Joshua A. Acklin, Michael S. Abers, Magdalena A. Walkiewicz, Sarah L. Anzick, Muthulekha Swamydas, Simon Vautier, Mukil Natarajan, Andrew J. Oler, Daisuke Yamanaka, Katrin D. Mayer-Barber, Yoichiro Iwakura, David Bianchi, Brian Driscoll, Ken Hauck, Ahnika Kline, Nicholas S.P. Viall, Christa S. Zerbe, Elise M.N. Ferré, Monica M. Schmitt, Tom DiMaggio, Stefania Pittaluga, John A. Butman, Adrian M. Zelazny, Yvonne R. Shea, Cesar A. Arias, Cameron Ashbaugh, Maryam Mahmood, Zelalem Temesgen, Alexander G. Theofiles, Masayuki Nigo, Varsha Moudgal, Karen C. Bloch, Sean G. Kelly, M. Suzanne Whitworth, Ganesh Rao, Cindy J. Whitener, Neema Mafi, Juan Gea-Banacloche, Lawrence C. Kenyon, William R. Miller, Katia Boggian, Andrea Gilbert, Matthew Sincock, Alexandra F. Freeman, John E. Bennett, Rodrigo Hasbun, Constantinos M. Mikelis, Kyung J. Kwon-Chung, Yasmine Belkaid, Gordon D. Brown, Jean K. Lim, Douglas B. Kuhns, Steven M. Holland, Michail S. Lionakis

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Figure 4

Dectin-1 and CARD9 promote TNF-α and IL-1β production during experimental Corynespora cassiicola phaeohyphomycosis that enhances macrophage C. cassiicola killing.

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Dectin-1 and CARD9 promote TNF-α and IL-1β production during experimenta...
(A) Cytokine analysis in the infected footpad homogenates (WT n = 12 mice, Clec7a–/– n = 12 mice, Card9–/– n = 7 mice) on day 3 after infection. Each data point represents an individual mouse; data were pooled from 2 independent experiments. (B) Footpad swelling in Il1r–/– (day 5: WT n = 24, KO n = 23, 3 pooled experiments; day 10: WT n = 16, KO n = 20, 4 pooled experiments), Il1b–/– (WT n = 7, KO n = 5, 1 experiment), and Tnfa–/– (day 5: WT n = 13, KO n = 15, 2 pooled experiments; day 10: WT n = 5, KO n = 15, 2 pooled experiments) mice, relative to WT controls. (C) Total numbers of neutrophils (live CD45+CD11b+Ly6G+) and macrophages (live CD45+CD11b+MHCIIhiF4/80+) in the infected footpad on day 3 after infection (n = 6 mice per group), measured using flow cytometry. (D) IL-1β and TNF-α production within footpad macrophages on day 3 after infection in Clec7a–/– (n = 7) and Card9–/– mice (n = 6), normalized to the WT controls (n = 6). Each data point represents an individual mouse; data were pooled from 2 independent experiments and analyzed by 1-way ANOVA with Dunnett’s correction. (E) Results of an in vitro C. cassiicola killing assay with bone marrow–derived macrophages, prestimulated for 24 hours with TNF-α, IL-1β, or both. Killing was determined by measuring β-D-glucan levels in the culture supernatant. Bar graph shows the mean ± SEM for 2 independent experiments; overlaid dot plot shows technical replicates from one of these experiments. (F) Schematic representation of the proposed model of anti–C. cassiicola immunity in the footpad of WT, Dectin-1–deficient, and CARD9-deficient mice. Data in panels A and B were analyzed by 2-way ANOVA with Bonferroni’s correction. Data in panel E were analyzed by unpaired, 2-tailed t test. *P < 0.05; **P < 0.01; ***P < 0.005; ****P < 0.0001.