TY - JOUR
T1 - Cholesterol and sphingomyelin are critical for Fcγ receptor- mediated phagocytosis of Cryptococcus neoformans by macrophages
AU - Bryan, Arielle M.
AU - You, Jeehyun Karen
AU - Li, Guangtao
AU - Kim, Ji Hyun
AU - Singh, Ashutosh
AU - Morstein, Johannes
AU - Trauner, Dirk
AU - de Sá, Nívea Pereira
AU - Normile, Tyler G.
AU - Farnoud, Amir M.
AU - London, Erwin
AU - Del Poeta, Maurizio
N1 - Funding Information:
Funding and additional information—This work was supported by the National Institutes of Health grants AI136934, AI116420, and AI125770 (to M. D. P.) and GM122493 (to E. L.), and the Merit Review Grant I01BX002924 from the Veterans Affairs Program (to M. D. P.). M. D. P. is a recipient of the Research Career Scientist Award (IK6 BX005386) and a Burroughs Welcome Investigator in Infectious Diseases at the Veterans Administration Medical Center in Northport, NY. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Publisher Copyright:
© 2021 THE AUTHORS.
PY - 2021/12/1
Y1 - 2021/12/1
N2 - Cryptococcus neoformans is a fungal pathogen that causes lifethreatening meningoencephalitis in lymphopenic patients. Pulmonary macrophages comprise the first line of host defense upon inhalation of fungal spores by aiding in clearance but can also potentially serve as a niche for their dissemination. Given that macrophages play a key role in the outcome of a cryptococcal infection, it is crucial to understand factors that mediate phagocytosis of C. neoformans. Since lipid rafts (high-order plasma membrane domains enriched in cholesterol and sphingomyelin [SM]) have been implicated in facilitating phagocytosis, we evaluated whether these ordered domains govern macrophages' ability to phagocytose C. neoformans. We found that cholesterol or SM depletion resulted in significantly deficient immunoglobulinG(IgG)-mediated phagocytosis of fungus. Moreover, repletion of macrophage cells with a raft-promoting sterol (7-dehydrocholesterol) rescued this phagocytic deficiency, whereas a raft-inhibiting sterol (coprostanol) significantly decreased IgG-mediated phagocytosis of C. neoformans. Using a photoswitchable SM(AzoSM), we observed that the raftpromoting conformation (trans-AzoSM) resulted in efficient phagocytosis, whereas the raft-inhibiting conformation (cis- AzoSM) significantly but reversibly blunted phagocytosis. We observed that the effect on phagocytosis may be facilitated by Fcγ receptor (FcγR) function, whereby IgG immune complexes crosslink to FcγRIII, resulting in tyrosine phosphorylation of FcR γ-subunit (FcRγ), an important accessory protein in the FcγR signaling cascade. Correspondingly, cholesterol or SM depletion resulted in decreased FcRγ phosphorylation. Repletion with 7- dehydrocholesterol restored phosphorylation, whereas repletion with coprostanol showed FcRγ phosphorylation comparable to unstimulated cells. Together, these data suggest that lipid rafts are critical for facilitating FcγRIII-mediated phagocytosis of C. neoformans.
AB - Cryptococcus neoformans is a fungal pathogen that causes lifethreatening meningoencephalitis in lymphopenic patients. Pulmonary macrophages comprise the first line of host defense upon inhalation of fungal spores by aiding in clearance but can also potentially serve as a niche for their dissemination. Given that macrophages play a key role in the outcome of a cryptococcal infection, it is crucial to understand factors that mediate phagocytosis of C. neoformans. Since lipid rafts (high-order plasma membrane domains enriched in cholesterol and sphingomyelin [SM]) have been implicated in facilitating phagocytosis, we evaluated whether these ordered domains govern macrophages' ability to phagocytose C. neoformans. We found that cholesterol or SM depletion resulted in significantly deficient immunoglobulinG(IgG)-mediated phagocytosis of fungus. Moreover, repletion of macrophage cells with a raft-promoting sterol (7-dehydrocholesterol) rescued this phagocytic deficiency, whereas a raft-inhibiting sterol (coprostanol) significantly decreased IgG-mediated phagocytosis of C. neoformans. Using a photoswitchable SM(AzoSM), we observed that the raftpromoting conformation (trans-AzoSM) resulted in efficient phagocytosis, whereas the raft-inhibiting conformation (cis- AzoSM) significantly but reversibly blunted phagocytosis. We observed that the effect on phagocytosis may be facilitated by Fcγ receptor (FcγR) function, whereby IgG immune complexes crosslink to FcγRIII, resulting in tyrosine phosphorylation of FcR γ-subunit (FcRγ), an important accessory protein in the FcγR signaling cascade. Correspondingly, cholesterol or SM depletion resulted in decreased FcRγ phosphorylation. Repletion with 7- dehydrocholesterol restored phosphorylation, whereas repletion with coprostanol showed FcRγ phosphorylation comparable to unstimulated cells. Together, these data suggest that lipid rafts are critical for facilitating FcγRIII-mediated phagocytosis of C. neoformans.
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U2 - 10.1016/j.jbc.2021.101411
DO - 10.1016/j.jbc.2021.101411
M3 - Article
C2 - 34793834
AN - SCOPUS:85120802877
SN - 0021-9258
VL - 297
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 6
M1 - 101411
ER -