A hallmark of chronic infection with lymphatic filarial parasites is the development of lymphatic disease which often results in permanent vasodilation and lymphedema, but all of the mechanisms by which filarial parasites induce pathology are not known. Prior work showed that the asparaginyl-tRNA synthetase (BmAsnRS) of Brugia malayi, an etiological agent of lymphatic filariasis, acts as a physiocrine that binds specifically to interleukin-8 (IL-8) chemokine receptors. Endothelial cells are one of the many cell types that express IL-8 receptors. IL-8 also has been reported previously to induce angiogenesis and vasodilation, however, the effect of BmAsnRS on endothelial cells has not been reported. Therefore, we tested the hypothesis that BmAsnRS might produce physiological changes in endothelial by studying the in vitro effects of BmAsnRS using a human umbilical vein cell line EA.hy926 and six different endothelial cell assays. Our results demonstrated that BmAsnRS produces consistent and statistically significant effects on endothelial cells that are identical to the effects of VEGF, vascular endothelial growth factor. This study supports the idea that new drugs or immunotherapies that counteract the adverse effects of parasite-derived physiocrines may prevent or ameliorate the vascular pathology observed in patients with lymphatic filariasis.
Asparagine‐tRNA synthetase is an enzyme which belongs to the class‐IIb aminoacyl‐tRNA synthetases(AARSs) an heterogeneous family of enzymes,that play a role in protein biosynthesis. Brugi Malayi parasites secrete this 63kDa high molecular weight enzyme. It has not been documented clearly,how humans infected with filariasis have lymphatic dysfunction. We have cloned and purified the AsnRs enzyme to evaluate the role played by this enzyme in angiogenesis in Filarial patients.The recombinant plasmid of pET‐15B encoding Brugia malayi Asparagine‐tRNA synthetase was transformed into the competent cells of E.coli BL21(DE3),induced to express by IPTG,purified by Immobilized metal ion affinity chromatography and identified by western blotting. Purified Recombinant Brugia malayi AsnRS was used to perform cellular based assays using endothelial cells‐ MTT assay,Chemotactic assay,ring formation assay and tube formation assay in EAhy926 cells.We also carried out angiogenesis assays in chick chorioallantoic membrane (CAM) models. Recombinant AsnRS induces proliferation in MTT assay,migration in chemotaxis assay,formation of endothelial ring structure in ring formation assay and tubular structures in matric gel assay. Additionally,BmAsnRs promotes the formation and widening of blood vessel mediated angiogenesis in CAM model. Our results showed the enzyme BmAsnRs to be a potent pro‐angiogenic mediator in vitro and CAM models. These results throw light on the possibility of AsnRs as a drug target for the control of Filariasis and thus this enzyme can be targeted for the control of angiogenesis‐associated pathology in Filariasis.
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