Project description:Malaria is a disease with diverse symptoms depending on host immune status and pathogenicity of Plasmodium parasites. The continuous parasite growth within a host suggests mechanisms of immune evasion and/or inhibition. To identify pathways commonly inhibited by malaria infection, we infected C67BL/6 mice with four Plasmodium yoelii strains causing different disease phenotypes and 24 progeny of a genetic cross. mRNAs from mouse spleens day 1 and/or day 4 post infection (p.i.) were hybridized to a mouse microarray to identify activated or inhibited pathways, upstream regulators, and linkages to parasite genetic loci. Strong interferon responses were observed after infection with N67 strain, whereas initial inhibition and later activation of hematopoiesis pathways were found after infection with 17XNL parasite. Inhibition of pathways such as Th1 activation, dendritic cell (DC) maturation, and NFAT immune regulation were observed in mice infected with all the parasite strains day 4 p.i., suggesting universally inhibited immune pathways. Treatment of infected mice with antibodies against T cell receptors OX40 or CD28 to activate malaria-inhibited pathways enhanced host survival. Controlled activation of these pathways may provide important strategies for better disease management and for developing an effective vaccine.
Project description:To study miRNA expression profiles during highly pathogenic avian influenza virus infection, we conducted global miRNA expression profiling in human lung epithelial cells (A549) with or without H5N1 IAV infection. .
Project description:Innate immune memory responses (also termed ‘trained immunity’) have been described in monocytes after BCG vaccination and after stimulation in vitro with microbial and endogenous ligands such as muramyl dipeptide, β-glucan, oxidized LDL, and MSU crystals. Whether clinical infections are also capable of inducing a trained immunity phenotype has not been studied. We evaluated whether Plasmodium falciparum infection can induce innate immune memory by assessing monocyte epigenetic, transcriptional and functional (cytokine production) programs from five volunteers undergoing controlled human malaria infection. During acute infection monocytes produced lower amounts of inflammatory cytokines upon secondary stimulation, but 36 days after malaria infection they produced significantly higher IL-6 and TNF-α in response to various stimuli. Furthermore, transcriptomic and epigenomic data analysis revealed a clear reprogramming of monocytes after malaria infection. Plasmodium challenge induces a long-term deposition of H3K4me3 at the promoter regions of several inflammatory genes of monocytes, these changes remaining stable for several weeks after infection. These findings demonstrate an epigenetic basis of trained immunity in the model of controlled in vivo human malaria infection.
Project description:Cerebral malaria (CM) is one of the most severe complications of malaria infection. There is evidence that repeated parasite exposure promotes resistance against CM, as indicated by the low incidence of CM in adults in malaria-endemic regions. However, the immunological basis of this infection-induced resistance remains poorly understood. Here, a microarray study done utilising the tractable Plasmodium berghei ANKA model of experimental cerebral malaria (ECM), we show that three rounds of infection and drug-cure protects against the development of ECM during a subsequent fourth infection.
Project description:Using genome-wide expression profiles from persons either experimentally challenged with malaria-infected mosquitoes or naturally-infected with Plasmodium falciparum malaria, we present details of the transcriptional changes that occur with infection and that are either commonly shared between subjects with pre-symptomatic and clinically apparent malaria or that distinguish these two groups. Our findings confirm and extend aspects of the earliest responses to malaria infection at the molecular level and which may be informative in elucidating how innate and adaptive immune responses may be modulated in different stages of infection. Experiment Overall Design: Compared samples from patients with naturally acquired malaria infection to those from volunteers in a challenge model vaccine trial.
Project description:Using genome-wide expression profiles from persons either experimentally challenged with malaria-infected mosquitoes or naturally-infected with Plasmodium falciparum malaria, we present details of the transcriptional changes that occur with infection and that are either commonly shared between subjects with pre-symptomatic and clinically apparent malaria or that distinguish these two groups. Our findings confirm and extend aspects of the earliest responses to malaria infection at the molecular level and which may be informative in elucidating how innate and adaptive immune responses may be modulated in different stages of infection. Keywords: Human PBMC samples from natural and experimentally (clinical trial) induced malaria