Dataset Information

Differential Gene Expression Profile of Human Neutrophils Cultured with Plasmodium falciparum-Parasitized Erythrocytes.

ABSTRACT: Neutrophils (PMNs) are the most abundant cellular component of our innate immune system, where they play central roles in the pathogenesis of and resistance to a broad range of diseases. However, their roles in malarial infection remain poorly understood. Therefore, we examined the transcriptional gene profile of human PMNs in response to Plasmodium falciparum-parasitized erythrocytes (iRBCs) by using oligonucleotide microarrays. Results revealed that PMNs induced a broad and vigorous set of changes in gene expression in response to malarial parasites, represented by 118 upregulated and 216 downregulated genes. The transcriptional response was characterized by the upregulation of numerous genes encoding multiple surface receptors, proteins involved in signal transduction pathways, and defense response proteins. This response included a number of genes which are known to be involved in the pathogenesis of malaria and other inflammatory diseases. Gene enrichment analysis suggested that the biological pathways involved in the PMN responses to the iRBCs included insulin receptor, Jak-STAT signaling pathway, mitogen-activated protein kinase (MAPK), and interleukin and interferon-gamma (IFN-?) signaling pathways. The current study provides fundamental knowledge on the molecular responses of neutrophils to malarial parasites, which may aid in the discovery of novel therapeutic interventions.

SUBMITTER: Terkawi MA

PROVIDER: S-EPMC6057315 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Differential Gene Expression Profile of Human Neutrophils Cultured with <i>Plasmodium falciparum</i>-Parasitized Erythrocytes.

Terkawi Mohamad Alaa MA Takano Ryo R Kato Kentaro K

Journal of immunology research 20180705

Neutrophils (PMNs) are the most abundant cellular component of our innate immune system, where they play central roles in the pathogenesis of and resistance to a broad range of diseases. However, their roles in malarial infection remain poorly understood. Therefore, we examined the transcriptional gene profile of human PMNs in response to <i>Plasmodium falciparum</i>-parasitized erythrocytes (iRBCs) by using oligonucleotide microarrays. Results revealed that PMNs induced a broad and vigorous set ...[more]

PMID: 30069491

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Project description:Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, involves clonal variants of the parasite protein P. falciparum erythrocyte membrane protein 1 (PfEMP1) and soluble serum factors. While rosetting is a well-known phenotypic marker of parasites associated with severe malaria, the reason for this association remains unclear, as do the molecular details of the interaction between the infected erythrocyte (IE) and the adhering erythrocytes. Here, we identify for the first time a single serum factor, the abundant serum protease inhibitor α2-macroglobulin (α2M), which is both required and sufficient for rosetting mediated by the PfEMP1 protein HB3VAR06 and some other rosette-mediating PfEMP1 proteins. We map the α2M binding site to the C terminal end of HB3VAR06, and demonstrate that α2M can bind at least four HB3VAR06 proteins, plausibly augmenting their combined avidity for host receptors. IgM has previously been identified as a rosette-facilitating soluble factor that acts in a similar way, but it cannot induce rosetting on its own. This is in contrast to α2M and probably due to the more limited cross-linking potential of IgM. Nevertheless, we show that IgM works synergistically with α2M and markedly lowers the concentration of α2M required for rosetting. Finally, HB3VAR06+ IEs share the capacity to bind α2M with subsets of genotypically distinct P. falciparum isolates forming rosettes in vitro and of patient parasite isolates ex vivo. Together, our results are evidence that P. falciparum parasites exploit α2M (and IgM) to expand the repertoire of host receptors available for PfEMP1-mediated IE adhesion, such as the erythrocyte carbohydrate moieties that lead to formation of rosettes. It is likely that this mechanism also affects IE adhesion to receptors on vascular endothelium. The study opens opportunities for broad-ranging immunological interventions targeting the α2M--(and IgM-) binding domains of PfEMP1, which would be independent of the host receptor specificity of clinically important PfEMP1 antigens.

Project description:BACKGROUND: Severe falciparum malaria anaemia (SMA) is a frequent cause of mortality in children and pregnant women. The most important determinant of SMA appears to be the loss of non-parasitized red blood cells (np-RBCs) in excess of loss of parasitized (p-) RBCs at schizogony. Based on data from acute SMA where excretion of haemoglobin in urine and increased plasma haemoglobin represented respectively less than 1% and 0.5% of total Hb loss, phagocytosis appears to be the predominant mechanism of removal of np- and p-RBC.Estimates indicate that np-RBCs are cleared in approximately 10-fold excess compared to p-RBCs. An even larger removal of np-RBCs has been described in vivax malaria anaemia. Estimates were based on two single studies both performed on neurosyphilitic patients who underwent malaria therapy. As the share of np-RBC removal is likely to vary between wide limits, it is important to assess the contribution of both np- and p-RBC populations to overall RBC loss, and disclose the mechanism of such variability. As available methods do not discriminate between the removal of np- vs p-RBCs, the purpose of this study was to set up a system allowing the simultaneous determination of phagocytosis of p- and np-RBC in the same sample. METHODS AND RESULTS: Phagocytosis of p- and np-RBCs was quantified in the same sample using double-labelled target cells and the human phagocytic cell-line THP-1, pre-activated by TNF and IFN? to enhance their phagocytic activity. Target RBCs were double-labelled with fluorescent carboxyfluorescein-succinimidyl ester (CF-SE) and the DNA label ethidium bromide (EB). EB, a DNA label, allowed to discriminate p-RBCs that contain parasitic DNA from the np-RBCs devoid of DNA. FACS analysis of THP-1 cells fed with double-labelled RBCs showed that p- and np-RBCs were phagocytosed in different proportions in relation to parasitaemia. CONCLUSIONS: The assay allowed the analysis of phagocytosis rapidly and with low subjective error, and the differentiation between phagocytosed p- and np-RBCs in the same sample. The presented method may help to analyse the factors or conditions that modulate the share of np-RBC removal in vitro and in vivo and lead to a better understanding of the pathogenesis of SMA.

Dataset Information

Differential Gene Expression Profile of Human Neutrophils Cultured with Plasmodium falciparum-Parasitized Erythrocytes.

Publications

Differential Gene Expression Profile of Human Neutrophils Cultured with <i>Plasmodium falciparum</i>-Parasitized Erythrocytes.

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