Prenatal malaria exposure alters the innate immune response, especially when there has been placental infection. This concludes a study led by ISGlobal, the Clinical Research Unit of Nanoro (CRUN) and the Institute of Tropical Medicine of Antwerp (ITM). These results, published in BMC Medicine, could help explain why some babies are more susceptible than others to developing malaria during the first year of life.
Despite the large-scale implementation of intermittent preventive treatment (IPTp) to prevent malaria during pregnancy, a large number of babies in endemic countries are born to mothers infected with Plasmodium falciparum. The type of prenatal exposure to malaria (if the infection is systemic or in the placenta) seems to affect the risk of contracting the disease in the first years of life, although it is not known how or why.
In this study, the research team evaluated whether prenatal exposure to malaria could alter the immune response called innate, which does not involve antibodies and constitutes the first line of defense of the newborn against malaria. To do this, they determined the type of prenatal exposure (i.e. systemic infection vs acute placental infection, chronic or passed) in a cohort of more than 300 mothers and their babies, in a clinical trial in Burkina Faso.
Using umbilical cord blood, they measured the ability to produce cytokines and chemokines (mediators of the immune system) after introducing molecules of many pathogens that are recognized by cells of the innate system.
Diagnose and treat malaria as soon as possible
The experts found that cord cells from babies exposed to malaria produced fewer mediators spontaneously in comparison with those from non-exposed babies. However, the cells of babies exposed to placental infection produced more cytokines and chemokines when stimulated. Certain biomarkers were associated with protection while others were associated with malaria risk during the first year of life, depending on the type of prenatal exposure.
“The different effect on the immune response of the newborn according to the type of exposure could explain why some babies are more susceptible than others to developing malaria,” explains Carlota Dobaño , ISGlobal researcher and co-director of the study together with Anna Rosanas-Urgell, ITM. “This also has implications for the response to other infections and vaccines based on adjuvants in these babies,” Dobaño adds.
Given that past placental infections, which probably occur in the early stage of pregnancy, have a considerable effect on the immune response of the newborn, the authors conclude that “it is necessary to establish a strategy to diagnose and treat malaria as soon as possible in the first trimester of pregnancy“.