Title : In vitro whole leukocyte infection model and detection of hydrophobic surface-binding protein A (HsbA) in L. corymbidera
Mucormycosis is a fungal infection caused by members of the order Mucorales, the most prominent group among zygosporic fungi (formerly ascribed to Zygomycetes). A total of 26 mucoralean species can infect humans. Among these, the highest proportions of infections are caused by Rhizopus arrhizus (ex: R. oryzae), Mucor circinelloides, and Lichtheimia corymbifera. In this study, we present the interaction between L. corymbifera with professional phagocytes which represents the first line of defense after infection. We demonstrate an in vitro whole leukocyte infection model and detection of hydrophobic surface-binding protein A (HsbA) by liquid chromatography-mass spectrometry analysis (LC-MS /MS). Initially, our analysis revealed the presence of the predominant spore coat protein (CotH) and HsbA on the surface of L. corymbifera sporangiospores. Interestingly, it was possible to detect the secretion of HsbA by L. corymbifera spores. Subsequently, coinfection (MOI 1:2) of leukocytes (1) with L. corymbifera spores (2) allowed detection of HsbA in the supernatant after 72 hours by LC-MS / MS. Finally, HsbA was shown to bind predominantly to monocytes and macrophages. In addition, this work established the antiproliferative and apoptosis-inducing effects of HsbA on MH -S cells. Altogether, our results suggested that HsbA plays a key role in interaction with the host immune system and helps to unravel the pathogenicity mechanism during mucormycosis.