Biomedical Engineering Reference
In-Depth Information
One example of a human pathogen is
Aspergillus fumigatus
which is a
fi lamentous fungus that is the predominant mould pathogen of humans. The
organism propagates itself by the airborne distribution of conidia, making
inhalational exposure constant and practically unavoidable (Goodley et al.
1994, Hospenthal et al. 1998, Woodcock et al. 2006). This poses a serious
problem for the immunocompromised population because
A. fumigatus
readily exploits deficiencies in pulmonary defences which results in
establishing life-threatening invasive infections. These infections continue
to be associated with a poor outcome (Marr et al. 2004, Morgan et al. 2005).
The limited impact of available therapies is fuelling efforts to identify new
molecular targets for antifungal therapy.
Apoptosis which is one type of PCD is gaining increasing attention
as a potential target in fungi. As the activation of caspase peptidases such
as metacaspases in fungi is one of the processes of apoptosis, exposing
the role of metacaspases in PCD may offer another focus for antifungal
therapies. Ultrastructural and biochemical changes that are characteristic
of apoptosis have been reported in pathogenic fungi, raising the possibility
that the manipulation of fungal death pathways could have merit as future
antifungal therapy.
In a 2008 review by Hamann and colleagues it was documented that
upon
A. fumigatus
infection, human cells responded by the induction of an
oxidative burst directed against the germinating spores which plays a role
in the demise of the fungus. Experimental data by Mousavi and Robson,
2004 indicates that an apoptotic pathway is induced by this interaction,
where
A. fumigatus
cultures treated with hydrogen peroxide which
possibly mimics the physiological process during the oxidative burst in
the pathogen displayed the classical hallmarks of apoptosis. Hydrogen
peroxide has also been shown to induce apoptosis in other fungi including
Saccharomyces cerevisiae
(Madeo et al. 1999, 2002) and
Candida albicans
(Phillips et al. 2003).
Anti-Fungal/Biocontrol Agents
It is also documented that plants also have the defence mechanism to
produce compounds that can induce apoptosis in their pathogens. One
such example is the ability of a tomato plant to produce the glycoside
α-tomatine, which is the major saponin in tomato, upon infection by
Fusarium oxysporum
. This effi ciently induces cell death in the fungus (Ito
et al. 2007).
There are many studies that reveal apoptotic inducers of fungi. One
such fungus
Saccharomyces cerevisiae
has been shown to undergo apoptosis in
response to several inducers including acetic acid, aluminium, amiodarone,
