Nitric Oxide Restoration &Heme Detoxification as Adjunctive Therapies for Cerebr

Summary

Principal Investigator: LEONARDO JOSE DE MOURA CARVALHO
Abstract: Cerebral malaria (CM) is a major complication of infection by Plasmodium falciparum. It affects mainly children under 5 years old in sub-Saharan Africa and shows a high mortality rate even when anti- malarial treatment is administered. Adjunctive therapies for CM capable of improving survival and decreasing incidence of sequelae are urgently needed. In the murine model of CM by Plasmodium berghei ANKA (PbA), CM has been associated to low nitric oxide (NO) bioavailability, and treatment with exogenous NO prevented CM development. On the other hand, plasma free heme has been incriminated in the genesis of CM. We propose that restoring NO and/or counteracting heme toxicity are potentially powerful approaches for adjunctive therapy of CM. The overall goal of this proposal is to define one or more treatment strategies based on NO restoration and/or free heme detoxification that show high efficacy as adjunctive therapy for cerebral malaria, using arthemeter as anti-malarial drug. Such a therapeutic procedure shall significantly improve survival in relation to arthemeter alone, ideally inducing negligible side effects and toxicity, and present good potential to be translated into clinical use. The PbA model of CM will be used. First, infected mice will be treated with three different dosages of each of the following NO donor compounds: DPTA-NO, NO-containing nanoparticles, S-nitroso- pegylated-albumin, GSNO, nitrite and nitroglycerin, as well as with the 5-phosphodiesterase inhibitor sildenafil. Compounds aimed at blocking the deleterious effect of heme (recombinant haptoglobin, hemopexin, protoporphyrin IX and mesoporphyrin IX), inducing hemeoxygenase-1 (HO-1: hyperbaric oxygen, curcumin, furan-2-yl-3-pyridin-2-yl-propenone, -deoxy-delta 12,14-prostaglandin J2) or providing anti-oxidant protection against heme-induced oxidative stress (N-Acethil cystein, desferoxamine) will be tested as well. The compounds able to prevent CM development in mice will be tested in a scheme of combined therapy with arthemeter with the purpose of rescuing mice with established CM at early or late stages. For each treatment, liver, kidney and respiratory physiology will be assessed to determine toxicity of the compounds, and in the case of NO donors blood pressure will also be monitored. In addition, the effect of the successful treatments on the brain microcirculation will be assessed by intravital microscopy and the expression of eNOS, nNOS, iNOS and HO-1will be determined. Finally, the compounds will also be tested in an in vitro system of co-culture of human brain endothelial cells and P. falciparum. We expect that to define one or more compounds that can be forwarded for clinical trials. Cerebral malaria (CM) is a major complication of infection by Plasmodium falciparum, causing hundreds of thousands of deaths every year particularly of children under 5 years old. Even receiving anti-malarial treatment, CM shows a 10-20% mortality rate, and survivors may present sequelae. Adjunctive therapies acting in concert with the anti- malarial treatment are then urgently needed to improve the rate and the quality of patient recovery. In this proposal, we intend to develop, using an animal model, adjunctive therapies based on nitric oxide restoration and/or heme detoxification that can be potentially translated into clinical use.
Funding Period: 2009-09-10 - 2014-08-31
more information: NIH RePORT