Candida Infection Biology – fungal armoury, battlefields ... - FINSysB

Poster number: 07
Candida albicans apoptotic markers during the interaction
with macrophages
A. Gil-Bona 1 , L. Monteoliva 1 , V. Cabezón 2 , M. Ramsdale 2 , C. Gil 1 .
1 2 Facultad de Farmacia. Universidad Complutense de Madrid. School of Biosciences,
University of Exeter, UK
Candida albicans is a dimorphic fungus member of the human microbiota that
causes a range of opportunistic infections from superficial to systemic. The last one
remains as a high rate of morbidity-mortality in patients from intensive care units,
surgery or cancer treatment. This is related with the problems of the few available
drugs, as the appearance of antifungal-drug resistance, and with the diagnostic
limitations.
The host-pathogen interaction is being studied using an in vitro interaction model
between Candida albicans and murine macrophages to analyze the fungus answer.
Previous proteomics and genomics studies of C. albicans upon interaction with
macrophages allowed us to detect the fungus response to adapt to the new
environment. This response includes the expression of several genes and proteins
related to the regulation of apoptosis (Fernández-Arenas et al., 2007).
In order to verify the apoptotic death of C. albicans cells in the interaction with
macrophages, several apoptotic markers have been analyzed after host-pathogen
interaction; namely, caspase-like enzymatic activity, generation of intracellular
reactive oxygen species (ROS), phosphatidyl-serine externalization and cell viability.
Also, TUNEL (TdT-mediated X-Dutp Nick end labelling) assays and transmission
electron microscopy (TEM) studies have been made.
These analyses have been carried out at different incubation times: 3h, 6h, 8h, 12h,
14h, 16h, 18h, 20h and 24 hours. The results showed that after 6 hours of C.
albicans-macrophage interaction, ROS and active caspase are present in the cell,
positive TUNEL cells were detected after 8 hours of interaction and the viability of
the yeast at these times is not compromised. Furthermore, chromatin condensation
and nuclear fragmentation were observed by TEM after 12 hours of interaction.
Data obtained in this work confirm a percentage up to 30% of apoptotic death of
C. albicans upon interaction with macrophages in ratio 1:1.
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