Protective role of Neuregulin-1 against cerebral malaria-induced neuronal injury and behavioral sequelae

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Human cerebral malaria (HCM) is a severe form of Plasmodium falciparum (P.f.) malaria associated with ~500,000 deaths in children annually and impaired brain function in some survivors. HCM is characterized by sequestration of parasitized red blood cells (pRBCs) in cerebral micro-circulation and induction of inflammatory mediators, brain swelling and impaired consciousness with unarousable coma. We have determined that circulating free heme and parasite histidine rich protein 2 (HRP2), by-products of pRBC lysis, are major causes of brain inflammation, blood-brain barrier (BBB) dysfunction, and brain injury associated with HCM. However, defining the mechanism(s) mediating these effects in HCM is challenging in the absence of suitable models. In vitro 2D cell culture, 3D brain organoid and animal models (ECM; Plasmodium berghei ANKA in C57BL/6) all indicate that heme and HRP2 induced cellular apoptosis, inflammation, and tissue disorganization. In ECM, heme causes brain vascular endothelial cell apoptosis, alters Angiopoietins 1 and 2 ratios, upregulates CXCL10, Heme Oxygenase 1, and tau as well as compromise BBB integrity through STAT3 signaling via matrix metalloproteinase three (MMP3). Following a screen for therapeutic agents against ECM, we identified Neuregulin- 1(NRG1), an 8 kDa neuropeptide currently undergoing clinical trials against heart failure, that attenuates ECM when delivered intravenously at 5µg/kg. NRG1 mediates phosphorylation of ErbB4 (receptor), activates AKT and inactivates STAT3 in human brain microvascular endothelial cells. ECM resistant mice (BALB/c) constitutively expressed higher levels of NRG1 in brain tissue than ECM susceptible (C57BL/6) mice. Since circulating NRG1 is severely depleted in both fatal HCM and ECM, levels of NRG1 need to be assessed prospectively to ascertain amounts needed for augmentation to mitigate HCM severity. Interestingly, CD8+Tcell PD1/PD-L1 signaling mediated ECM recovery and PD1 was upregulated by NRG1. Using a human stem cell- derived neurovascular unit (NVU; brain chip), ECM and human subjects, we will determine the mechanism by which NRG1 attenuates cerebral malaria. We hypothesize that therapeutic administration of NRG1 will attenuate heme and HRP2-induced NVU damage and ECM mortality via NRG1/ErbB4 and PD/PD-L1 signaling. Our objective is to functionally assess the key regulatory pathways mediated by NRG1 to attenuate ECM, and heme- and HRP2-induced NVU damage. The specific aims are: 1) to test the hypothesis that an algorithm, consisting of NRG1, heme, HRP2, and markers of neuronal injury and inflammation can predict HCM severity, mortality and neurobehavioral sequelae; 2) to test the hypothesis that NRG1/ErbB4 and PD1/PD-L1 signaling crosstalk protects against heme and HRP2-induced damage in human NVU; and 3) to test the hypothesis that NRG1 attenuates ECM brain injury and behavioral deficit via NRG1/ErbB4 and PD1/PD-L1 signaling. Understanding the role of NRG1 in cerebral malaria pathogenesis and sequelae in survivors will enable us to determine the feasibility of targeting NRG1 in clinical trials with the ultimate goal of improving the survival of children with HCM.