title: Caspase dependent programmed cell death in developing embryos: a potential target for therapeutic intervention against pathogenic nematodes.
abstract: BACKGROUND
  Successful embryogenesis is a critical rate limiting step for the survival and transmission of parasitic worms as well as pathology mediated by them. Hence, blockage of this important process through therapeutic induction of apoptosis in their embryonic stages offers promise for developing effective anti-parasitic measures against these extra cellular parasites. However, unlike in the case of protozoan parasites, induction of apoptosis as a therapeutic approach is yet to be explored against metazoan helminth parasites.
  
  
  RESULTS
  For the first time, here we developed and evaluated flow cytometry based assays to assess several conserved features of apoptosis in developing embryos of a pathogenic filarial nematode Setaria digitata, in-vitro as well as ex-vivo. We validated programmed cell death in developing embryos by using immuno-fluorescence microscopy and scoring expression profile of nematode specific proteins related to apoptosis [e.g. CED-3, CED-4 and CED-9]. Mechanistically, apoptotic death of embryonic stages was found to be a caspase dependent phenomenon mediated primarily through induction of intracellular ROS. The apoptogenicity of some pharmacological compounds viz. DEC, Chloroquine, Primaquine and Curcumin were also evaluated. Curcumin was found to be the most effective pharmacological agent followed by Primaquine while Chloroquine displayed minimal effect and DEC had no demonstrable effect. Further, demonstration of induction of apoptosis in embryonic stages by lipid peroxidation products [molecules commonly associated with inflammatory responses in filarial disease] and demonstration of in-situ apoptosis of developing embryos in adult parasites in a natural bovine model of filariasis have offered a framework to understand anti-fecundity host immunity operational against parasitic helminths.
  
  
  CONCLUSIONS
  Our observations have revealed for the first time, that induction of apoptosis in developing embryos can be a potential approach for therapeutic intervention against pathogenic nematodes and flow cytometry can be used to address different issues of biological importance during embryogenesis of parasitic worms.
authors.affiliation: Department of Infectious Disease Biology, Institute of Life Sciences, DBT, Ministry of Science and Technology, Government of India, Bhubaneswar, India.
authors.forename: Alok Das
authors.initials: AD
authors.lastname: Mohapatra
authors.forename: Sunil
authors.initials: S
authors.lastname: Kumar
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Satapathy
authors.forename: Balachandran
authors.initials: B
authors.lastname: Ravindran
mesh_terms: D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002738:Chloroquine / Q000494:pharmacology; D003474:Curcumin / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004625:Embryo, Nonmammalian; D005260:Female; D005434:Flow Cytometry; D015227:Lipid Peroxidation; D008856:Microscopy, Fluorescence; D009285:Naphthoquinones / Q000494:pharmacology; D011319:Primaquine / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D017182:Setaria Nematode / Q000187:drug effects* / Q000196:embryology* / Q000201:enzymology
chemical_list: D000969:Antinematodal Agents; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; C089224:Ced-4 protein, C elegans; D009285:Naphthoquinones; D017382:Reactive Oxygen Species; D002738:Chloroquine; D045304:Cytochromes c; D020169:Caspases; D003474:Curcumin; D011319:Primaquine; C014758:plumbagin