Widespread expression of MRP8 and MRP14 in human cerebral malaria by microglial cells.

Human cerebral malaria (CM) is an often fatal infection. The cascades of signaling events resulting in tissue trauma and coma are only slowly becoming unraveled. Here we report that microglial cells--sensitive cellular sensors of threats to the central nervous system--in CM express the myeloid-related proteins MRP8 (S100A8) and MRP14 (S100A9), Ca2+-binding sensor proteins of activated monocytes. Surprisingly, microglial activation was widespread throughout the brain in white and gray matter and not limited to areas of petechial bleedings or sequestration of infected erythrocytes. Further, apoptosis/necrosis is prominent in CM; not only leukocytes appeared apoptotic, neurons also appeared damaged and DNA fragmentation was revealed by in situ nick translation. Thus, a prominent feature of human CM is activation of microglia, and analysis of these reactive microglia might further promote our understanding of CM pathology and guide development of future therapeutic intervention of the local reactive processes.