Interaction of Curvularia lunata with human neutrophil granulocytes
The genera Curvularia and Bipolaris contain closely related melanin producing filamentous fungi. While Bipolaris species infect only plants, there are some opportunistic human pathogenic species in Curvularia, such as C lunata, C. spicifera or C. hawaiiensis. These species typically cause phaeohyphomycoses, which can manifest as local infections (e.g. keratitis, sinusitis and cutaneous lesions) in immunocompetent or invasive mycoses with frequent involvement of the central nervous system in immunocompromised patients. Although their plant-fungal interactions have been intensively studied, only little information available about the host response to these fungi in case of human infections. Aim of this study was to investigate the neutrophil’ response to the hyphal forms of Curvularia and Bipolaris species in comparison with that to Aspergillus fumigatus.
In the study, C. lunata SZMC 23759 and A. fumigatus SZMC 23245, both isolated from human eye infections, and B. zeicola BRIP 19582b from plant leaf were examined. Release of O2•- and H2O2 from neutrophils were measured in the presence or the absence of the supernatant of germinating conidia and after serum treatment. Activation and survival of neutrophils were checked by measuring myeloperoxidase and LDH release, respectively.
ROS production of neutrophils in interaction with the three fungi were compared. It is already known that Aspergillus species induce ROS production of neutrophils only after serum treatment. Similarly, C. lunata and B. zeicola were also able to induce H2O2 release only after serum opsonisation. Infection with C. lunata caused an increment in the extracellular H2O2 after 30 minutes, while a decline was noticed after 60 minutes. During the interaction, an H2O2 specific signal could be detected from the conidia of C. lunata. Viability of fungi were also checked after co-incubation.
This research was supported by the grants „Lendület” LP2016-8/2016, GINOP-2.3.2-15-2016-00035 and UNKP-17-3 New National Excellence Program of the Ministry of Human Capacities.