CotH3 mediates fungal invasion of host cells during mucormycosis
Teclegiorgis Gebremariam, … , Michael R. Yeaman, Ashraf S. Ibrahim
Teclegiorgis Gebremariam, … , Michael R. Yeaman, Ashraf S. Ibrahim
Published December 20, 2013
Citation Information: J Clin Invest. 2014;124(1):237-250. https://doi.org/10.1172/JCI71349.
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CotH3 mediates fungal invasion of host cells during mucormycosis

Abstract

Angioinvasion is a hallmark of mucormycosis. Previously, we identified endothelial cell glucose-regulated protein 78 (GRP78) as a receptor for Mucorales that mediates host cell invasion. Here we determined that spore coat protein homologs (CotH) of Mucorales act as fungal ligands for GRP78. CotH proteins were widely present in Mucorales and absent from noninvasive pathogens. Heterologous expression of CotH3 and CotH2 in Saccharomyces cerevisiae conferred the ability to invade host cells via binding to GRP78. Homology modeling and computational docking studies indicated structurally compatible interactions between GRP78 and both CotH3 and CotH2. A mutant of Rhizopus oryzae, the most common cause of mucormycosis, with reduced CotH expression was impaired for invading and damaging endothelial cells and CHO cells overexpressing GRP78. This strain also exhibited reduced virulence in a diabetic ketoacidotic (DKA) mouse model of mucormycosis. Treatment with anti-CotH Abs abolished the ability of R. oryzae to invade host cells and protected DKA mice from mucormycosis. The presence of CotH in Mucorales explained the specific susceptibility of DKA patients, who have increased GRP78 levels, to mucormycosis. Together, these data indicate that CotH3 and CotH2 function as invasins that interact with host cell GRP78 to mediate pathogenic host-cell interactions and identify CotH as a promising therapeutic target for mucormycosis.

Authors

Teclegiorgis Gebremariam, Mingfu Liu, Guanpingsheng Luo, Vincent Bruno, Quynh T. Phan, Alan J. Waring, John E. Edwards Jr., Scott G. Filler, Michael R. Yeaman, Ashraf S. Ibrahim

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Figure 4

Anti-CotH3 Abs block endothelial cell endocytosis of and damage by R. oryzae.

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Anti-CotH3 Abs block endothelial cell endocytosis of and damage by R. or...
Endothelial cells were incubated with 50 μg/ml anti-CotH3, with serum from the same rabbit prior to vaccination (preserum control), for 1 hour prior to addition of R. oryzae germlings. (A) Adherence and endocytosis (determined by differential fluorescence) assays were carried out using endothelial cells split on 12-mm glass coverslips. Blocking of CotH3 and CotH2 (since the Abs react to CotH2 proteins) abrogated endocytosis of R. oryzae by endothelial cells. Data were derived from >700 fungal cells interacting with approximately 200 endothelial cells/group/experiment, with an average of 59% cells being endocytosed in the control. (B) Damage was carried out using the 96-well plate 51Cr release method. Blocking of CotH3 and CotH2 reduced the ability of R. oryzae to cause endothelial cell damage. *P < 0.01 vs. either control, Wilcoxon rank-sum test. n = 6 slides or wells per group from 3 (A) or 2 (B) independent experiments. Data are median ± interquartile range.