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Induction of TRAIL and TNF-alpha-dependent Apoptosis in Human mDCs by Microfilariae of Brugia Malayi

ABSTRACT: Dysregulation of professional APC has been postulated as a major mechanism underlying Ag-specific T cell hyporesponsiveness in patients with patent filarial infection. To address the nature of this dysregulation, dendritic cells (DC) and macrophages generated from elutriated monocytes were exposed to live microfilariae (mf), the parasite stage that circulates in blood and is responsible for most immune dysregulation in filarial infections. DC exposed to mf for 24–96 h showed a marked increase in cell death and caspase-positive cells compared with unexposed DC, while mf exposure did not induce apoptosis in macrophages. Interestingly, 48 h exposure of DC to mf induced mRNA expression of the pro-apoptotic gene TRAIL and both mRNA and protein expression of TNF-alpha. mAb to TRAIL-R2, TNF-R1, or TNF-alpha partially reversed mf-induced cell death in DC, as did knocking down the receptor for TRAIL-R2 using small interfering RNA. Mf also induced gene expression of BH3-interacting domain death agonist (Bid) and protein expression of cytochrome c in DC; mf-induced cleavage of Bid could be shown to induce release of cytochrome c, leading to activation of caspase 9. Our data suggest that mf induce DC apoptosis in a TRAIL- and TNF-alpha-dependent fashion. Keywords: Dendritic Cell, Parasite, Human, Microfilariae

ORGANISM(S): Homo sapiens

PROVIDER: GSE12787 | GEO | 2008/09/17

SECONDARY ACCESSION(S): PRJNA112783

REPOSITORIES: GEO

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Project description:The zoonotic mosquito-borne filarial nematode Dirofilaria repens causes subcutaneous and ocular infections in dogs, cats and humans. Microfilariae (mf) are taken up by mosquitoes from infected vertebrate hosts which develop in the mosquito to the infectious third stage larvae (L3). These are transmitted to new vertebrate hosts and develop over two further moults to adult worms. The aims of the project were 1) the de novo sequencing and annotation of the D. repens genome and 2) comparative transcriptome analyses of the developmental stages mf and L3 as we hypothesized remarkable differences in gene expression between the different developmental stages. Genomic DNA was obtained from adult male D. repens. RNA was extracted from microfilariae from naturally infected dogs and from L3 produced in Aedes aegypti mosquitoes fed on blood spiked with microfi-lariae. The 99.59 MB genome was around 17% larger than that of the related species D. immitis (dog heartworm) and contained 8.9% fewer predicted genes (10,357). Around 1.8% of identified proteins (206/11,262) could not be mapped to D. immitis. Out of these, 6 (2.9 %) presented an ortholog in all other considered filarial nematodes (e.g. Loa loa) and Caenorhabditis elegans. A sig-nificantly higher number of D. repens proteins as compared to D. immitis mapped to the filarial nem-atode L. loa, reflecting the similarity in biology of D. repens and L. loa. A total of 876 genes were differentially expressed, of which 591 could be annotated in UniProtKB/Swiss-Prot. In particular, 155 genes with a UniProtKB/Swiss-Prot annotation to C. elegans and filarial nematodes were upregulat-ed in the L3 and 57 in the mf stage, respectively. Fifteen GO BP (Gene Ontology Biological Pro-cesses) were significantly enriched for the L3 group and 12 for the mf. These data provide first in-sight into the differential gene expression profiles of this filarial nematode and can serve for future investigations of metabolic processes and stage-specific diagnostics.

Project description:Filarial nematodes are arthropod-borne nematodes that cause a variety of economically important diseases such as onchocerciasis (river blindness), lymphatic filariasis, and heartworm disease. The most widespread filarial disease of humans is lymphatic filariasis, caused by worms in the genera Wuchereria and Brugia. Lymphatic filariasis is an economic and social burden in endemic countries and affects approximately 119 million people worldwide (Michael, 1997). In humans, the worms live in and block the lymph vessels, causing improper flow of lymph, and inflammation of the lymphatic system. The symptoms are fever, swollen limbs and genitals, generalized malaise, and can progress to a debilitating condition known as elephantiasis This research focuses on the transmission of these worms to the disseminating mosquito host, and it is based on the interesting observation that mf must be at least 7 days old to successfully infect the mosquito (de Hollanda, 1982). Newborn mf that have not â??maturedâ?? cannot successfully penetrate the midgut of the mosquito, and subsequently cannot develop to the L3 stage (Fuhrman, 1987). Previous work done by another group 20 years ago suggests that the molecular makeup of the worm surface changes during this maturation process (Furman, 1983 a and b). We used microarray analysis to characterize changes in gene expression that take place during the mf maturation process. Understanding the gene expression changes that occur as the mf mature will allow us to understand the nature of the philological transition that allows mf to move from the human to the mosquito host. With this information in hand, we can eventually identify parasite molecules that could be targeted to either stop parasite reproduction or prevent transmission of the mf to the mosquito. This would stop parasite transmission in endemic areas. This SuperSeries is composed of the following subset Series: GSE14939: Brugia pahangi mature vs immature microfilariae GSE14940: Brugia malayi mature vs immature microfilariae Refer to individual Series

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Induction of TRAIL and TNF-alpha-dependent Apoptosis in Human mDCs by Microfilariae of Brugia Malayi

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