Malaria is a disease with devastating medical complications mostly in children and pregnant women. More than 3 billion people live in areas at risk for malaria transmission. Intensified international efforts have reduced the malaria burden but an estimated 200 million clinical cases and 700,000 deaths were recently reported. Prevention of malaria infection, identification of adjunctive therapies, and development of new anti-malarial drugs with consistent efficacy that can reduce organ damage in children and pregnant women are high priority public health and scientific objectives. In pregnant women, poor birth outcomes induced by maternal Plasmodium falciparum infection range from pre-term delivery and intrauterine growth restriction to stillbirth and abortion. These consequences have been linked to a number of malaria-induced placental pathologies. Importantly, histological evidence of necrotic cell death is observed in human and murine placenta affected by malaria, but the underlying mechanisms that lead to this outcome are poorly understood. The objective of this exploratory application is to use our established experimental systems, a unique mouse model, an in vitro primary syncytiotrophoblast model and samples derived from women naturally exposed to malaria during pregnancy, to show that autophagy (a cellular, regenerative/recycling response to stress-related damage) and necroptosis (inflammatory cell death) occur in malaria-exposed trophoblast and are mechanistically linked in placental malaria. Importantly, to our knowledge, this study will represent the first time that necroptosis will be investigated in human trophoblast. The central hypothesis for the proposed research is that PM induces hyperautophagic responses in trophoblast that end in necrotic cell death or necroptosis. The rationale for the proposed work is that improved understanding of the mechanistic basis of PM pathogenesis can reveal new therapeutic targets for prevention of malaria-induced poor pregnancy outcomes. To achieve the goals of this project, two Specific Aims will be undertaken.
The first Aim will seek to establish that trophoblastic autophagy occurs in response to PM. To accomplish this, molecular markers and subcellular structural indicators of autophagy will be assessed in conceptuses from malaria- infected mice, placental tissues from malaria-exposed women and primary human syncytiotrophoblast exposed to malaria in vitro.
The second Aim will explore the process of necroptosis in malaria-exposed primary syncytiotrophoblast.
This Aim will investigate conditions under which malaria induces necroptosis in primary trophoblasts. These conditions will then be used to identify the molecular pathways that lead to necroptosis, with a focus on apoptosis and autophagy. This will be achieved via a combination of measurement of molecular markers of these processes and live-cell imaging. Successful completion of this research proposal promises to expand understanding of the mechanistic basis for malaria-associated placental damage and fetal compromise and could pave the way for new treatment modalities for malaria- exposed pregnant women. Progress on this front is critical given the lack of a protective malaria vaccine and the perpetual emergence of parasite resistance to frontline anti-malarial drugs. New adjunct therapies for malaria during pregnancy could contribute to significant reduction in the morbidity and fetal compromise associated with poor pregnancy outcome during malaria infection. Finally, this work will expand understanding of trophoblast responses to stress and will therefore have implications for other pregnancy conditions that are associated with placental damage.
Although it is clear that placental damage and dysfunction underlie poor birth outcomes associated with maternal malaria infection, the molecular mechanisms that underlie this damage remain very poorly understood. Exploration of these mechanisms, in particular cellular processes involved in response to inflammatory stress, could contribute to the development of improved diagnostics and therapeutic interventions that would reduce morbidity and mortality for at risk pregnant women and their infants.
| Shao, Qiang; Herrlinger, Stephanie; Yang, Si-Lu et al. (2016) Zika virus infection disrupts neurovascular development and results in postnatal microcephaly with brain damage. Development 143:4127-4136 |
