[16, 17, 25] Clearly new therapeutic strategies are required for this deadly disease. Such potential novel therapies can be better designed with comprehensive understanding of the mechanism of infection and its related host defence. Iron uptake from the host by

microorganisms is essential for the establishment and progression of infection since this element is required for the survival of living cells.[26] In a normal host, free iron is restricted by highly efficient iron sequesters such as transferrin, ferritin and lactoferrin.[26] Pathogens either devise strategies to obtain iron from the host by stripping iron from these sequesters (e.g. by siderophore production), or the tightly controlled free iron becomes more available in certain medical conditions. The unique susceptibility of certain patient populations to mucormycosis, but not to other pathogenic selleck chemicals fungi, point to the importance of iron uptake in the pathogenesis of mucormycosis.[3, 23] These include, hyperglycaemic, DKA and other forms of selleck inhibitor acidosis patients as well as deferoxamine-treated patients. All these patient categories suffer from elevated available serum iron. For example, the excessive glycosylation of proteins such as transferrin and ferritin, due to constant hyperglycaemia result in decreased iron affinity of these sequesters

which leads to the release of free ion in the blood stream and in cells.[27] Similarly, DKA and other forms of acidosis cause proton-mediated dissociation of iron from iron-sequestering proteins.[28] The increased levels of available iron enable enhanced growth of Mucorales in serum.[9, 28, 29] It is also known that DKA mice are more susceptible to mucormycosis infection than normal mice and iron chelation therapy using deferiprone or deferasirox protects DKA mice from mucormycosis.[29, 30] Subsequent studies confirmed the efficacy of deferasirox in treating experimental mucormycosis using the Drosophila fly model.[31] Patients with iron overload toxicity were used Adenosine triphosphate to be treated with the bacterial iron-siderophore, deferoxamine.

These patients were found to be extremely susceptible to deadly form of mucormycosis.[32-34] Subsequent studies demonstrated that although deferoxamine is an iron chelator from the perspective of the human host, Rhizopus spp. utilise ferrioxamine (the iron-rich form of deferoxamine) as a xeno-siderophore to obtain previously unavailable iron.[35, 36] It was found that ferrioxamine binds to a cell surface receptor on the surface of Rhizopus and through an energy dependent reductive step releases ferrous iron prior to transporting it across the fungal cell membrane without deferoxamine internalisation.[36] Subsequent studies demonstrated that reduction in the high-affinity iron permease FTR1 copies (Mucorales are multinucleated organisms) in R.