title: Plasmodium falciparum Heat Shock Protein 70 Lacks Immune Modulatory Activity.
abstract: BACKGROUND
  Heat shock protein 70 (Hsp70) family are conserved molecules that constitute a major part of the cell's protein folding machinery. The role of Hsp70s of parasitic origin in host cell immune modulation has remained contentious. This is largely due to the fact that several studies implicating Hsp70 in immune modulation rely on the use of recombinant protein derived from bacteria which is often fraught with lipopolysaccharide (LPS) contamination. For this reason, there is need to clarify the role of parasite Hsp70 in modulating host immune cells.
  
  
  OBJECTIVE
  The current study sought to investigate the role of Plasmodium falciparum Hsp70 (PfHsp70) in immune modulation.
  
  
  METHODS
  We expressed recombinant PfHsp70 using three bacterial expression hosts: E. coli XL1 Blue, E. coli ClearColi BL21 and Brevibacillus choshinensis, respectively. We further investigated the immunostimulatory capability of PfHsp70 by monitoring cytokine production by murine immune cells cultured in the presence of the protein.
  
  
  RESULTS
  Recombinant PfHsp70 produced using E. coli XL1 Blue expression host induced IL6 and IL8 cytokines. On the other hand, PfHsp70 produced in E. coli ClearColi and B. choshinensis expression systems was associated with no detectable traces of LPS and exhibited no immunomodulatory activity.
  
  
  CONCLUSIONS
  Our findings demonstrate that PfHsp70 does not possess immunomodulatory function. Furthermore, our study further confirm E. coli ClearColi and B. choshinensis as appropriate expression systems for the production of LPS-free recombinant protein.
authors.affiliation: Department of Biochemistry, Westville Campus, University of KwaZulu-Natal, Private Bag X54001, Durban 4000. South Africa.
authors.forename: Ofentse Jacob
authors.initials: OJ
authors.lastname: Pooe
authors.affiliation: Parasitology, Philipps University Marburg. Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Köllisch
authors.affiliation: Division of Innate Immunity, Priority Area Asthma and Allergies, Research Center Borstel; Airway Research Center North (ARCN), German Center for Lung Research (DZL), 5Borstel. Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Heine
authors.affiliation: Department of Biochemistry, School of Mathematical and Natural Sciences, University of Venda, Thoyoyandou. South Africa.
authors.forename: Addmore
authors.initials: A
authors.lastname: Shonhai
mesh_terms: D000818:Animals; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D006790:Host-Parasite Interactions / Q000276:immunology; D056747:Immunomodulation / Q000235:genetics; D016778:Malaria, Falciparum / Q000276:immunology* / Q000469:parasitology; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D017510:Protein Folding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology
chemical_list: D018840:HSP70 Heat-Shock Proteins; D011994:Recombinant Proteins
keywords: Plasmodium falciparum Hsp70; TLR2; TLR4; immune modulation; lipopolysaccharide; recombinant protein