Neurological dysfunction is an important complication of blood stage Plasmodium falciparum (Pf) infection and the syndrome is called cerebral malaria (CM). We have developed human serum albumin (HSA) nanoparticles (NPs) that are nanoscale aggregates of albumin as a carrier for drug delivery and conjugated anti-bloodstage Plasmodium drugs, including artemether (A) and artemisinin to these NPs. Our preliminary data indicate that our novel artemether-conjugated NPs (A-NPs) provide complete protection against experimental CM (eCM). A-NPs exhibit anti-parasite activity and are preferentially targeted to infected red blood cells (iRBCs) over uRBCs. Our control NPs (C-NPs), which are NPs without drug, provide significant (p<0.05) protection against eCM without affecting parasitemia. These findings suggest that A-NPs may exhibit both anti-parasite- and adjunctive-therapy effects in a single, easy to administer compound. There is currently no FDA-approved adjunctive therapy of CM to ameliorate the pathogenic host response during CM and to decrease mortality in the 15-30% of CM patients who die after adequate anti-parasite chemotherapy. In addition, this adjunctive therapy to ameliorate the pathogenic host response may also decrease the neurological impairment after Pf infection that results in life-long disability for African children who survive CM. We use the well-defined, reproducible P. berghei ANKA infection of mice as our model for CM (i.e., eCM). We hypothesize that our novel nanoparticles protect from development of eCM by decreasing pathogenic processes leading to eCM, i.e., vasogenic edema, oxidant stress, inflammation, sequestration, and coagulopathy. The efficacy of NPs as adjunctive therapy against eCM is tested in Aim 1. Mechanism(s) of action of NPs as adjunctive therapy are tested in Aim 2. Cerebral malaria is a syndrome comprised of multiple pathogenic processes that includes brain edema, Pf- infected red blood cell sequestration, oxidant stress, coagulopathy, and inflammation. Vasogenic edema is observed by magnetic resonance imaging in African children with CM; the vasogenic edema occurs in Indian adults with CM but is less pronounced. Our preliminary data indicate that C-NPs significantly (p<0.05) decrease vascular leak measured by Evans Blue dye extrusion into brain during eCM compared with vehicle controls. A-NPs decreased vascular leak even further than C-NPs to levels similar to those in uninfected mice. Our preliminary data therefore suggest that NPs function as adjunctive therapy in eCM by reducing vascular leak. We will also assess the extent to which other key pathogenic mechanisms in eCM are affected by our eCM-protective NPs. Patients with CM and mice with eCM both exhibit oxidant stress, parasite sequestration, coagulopathy, and inflammation as possible pathogenic processes, so defining which mechanisms are significantly decreased by our eCM-protective A-NPs highlights targetable processes for additional future drug development. This proposal meets R21 exploratory grant guidelines because it is focused on assessing the efficacy of a new drug with undefined mechanisms for which there is little experimental support beyond our preliminary data. Follow-on studies will use the generated data for in-depth studies of mechanisms and to move the NPs to the clinic.

Public Health Relevance

New approaches for adjunctive therapy to protect against neuronal dysfunction and death while the chemotherapy kills the Plasmodium falciparum (Pf) parasite are needed because (i) malaria is a leading infectious cause of mortality, (ii) neurological impairment due to Pf infection results in life-long disability, (iii) drug-resistance is emerging so more people may be afflicted with neuronal dysfunction, and (iv) cerebral malaria mortality occurs even in patients who have received adequate anti-parasite chemotherapy. We have developed novel artemether-conjugated, human serum albumin nanoparticles (A-NPs) that our preliminary data indicate function as both chemo- and adjunctive-therapy in experimental cerebral malaria. This proposal measures the efficacy of our A-NPs in Aim-1 and defines mechanisms of action in Aim-2.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Exploratory/Developmental Grants (R21)
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Clinical Neuroimmunology and Brain Tumors Study Section (CNBT)
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O'Neil, Michael T
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La Jolla Institute
San Diego
United States
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