| Abstract |
Phagocytosis is an evolutionary conserved process of the innate immunity among species.
Although it is highly conserved in all living organisms, the molecular mechanism that regulates
phagocytosis remains obscure. A small group of airborne filamentous fungi (molds), including
Aspergillus fumigatus, are considered to be emerging pathogens in a broad spectrum of patients
with immunodeficiencies. On a daily basis, we inhale numerous conidia of Asp.fumigatus that are
eliminated in immunocompetent host, by innate immune mechanisms. However, nowadays with
increase in numbers of immunosuppressed patients Aspergillus fumigatus is considered to be one
of the most threatening and emerging pathogen, leading to increasing numbers of Invasive
Aspergillosis and usually to high mortality rates (30%-50%). Previous studies in the lab have shown
that specialized mechanisms of non-canonical autophagy pathway play crucial role in host
pathogen interactions and in the fungus killing. It seems that, deregulations of iron homeostasis
and iron overload inside tissue macrophages are central risk factors for development of Invasive
Molds Infections (IMIs). However, the physiological mechanisms of iron homeostasis in
macrophages and the role of iron in immune effector functions are largely unknown. The aim of this
master thesis is to dissect the role of evolutionary conserved iron transporters in the phagosomes
that play a role in host defense against Asp.fumigatus. For this reason, we will focus on molecular
mechanisms specifically in the phagocytic cells that are essential in the host -pathogens interplay.
More precisely, we will utilize Drosophila melanogaster as an experimental genetic model, by
creating tissue specific conditional inactivation of this iron transporter genes in the Drosophila’s
phagocytic cells (here referred as hemocytes). The use of Drosophila melanogaster will give us the
chance to study mechanisms of iron deregulation in host cells and the molecular mechanisms
associated with the phagosome biogenesis, phagosome formation, maturation and
phagolysosomal fussion. In parallel, we will analyze the way how this iron transporter regulates not
only the phagosome biogenesis, but also iron balance in the mammalian CD14+ monocytes
focusing in the possible correlation with master regulators of the non-canonical pathway, such as
Reactive Oxygen Species production and the pH regulation in the phagosomal lumen, procedures
that lead to the P-L fusion and the killing of the pathogen. We will next identify in a cohort study
SNPs of the human homologue of this iron transporter and subsequently analyze the associated
genetic risk for IMI in the bone marrow transplant recipients provided by our collaborator (A.
Carvalho) by functionally characterizing iron regulation, effector functions in macrophages and the
efficiency of the killing of Asp.fumigatus in volunteers with the SNP of interest and in healthy
individuals.
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Exploring evolutionary conserved antifungal immune mechanisms in phagocytes
