Expression of monocyte heat shock protein 70 (HSP70) during malaria fever in the presence of antimalarial, anti-inflammatory drugs and β-haematin.
Year: 2017
Type: dissertation
Abstract: Malaria is an infectious disease caused by one of the parasitic Plasmodium species (Plasmodium falciparum, P. vivax, P. knowlesi, P. malariae, P. ovale).During the host response to malaria infection, periods of fever are experienced.Fever has been reported to decrease parasite growth but could be pathogenic as it has been found to increase cytoadherence between parasites and endothelial cells.During fever, host cells express a family of protective heat shock proteins that act as chaperones to prevent protein aggregation, and help renature denatured protein, and hence maintain cellular homeostasis.One of the main heat shock proteins expressed is heat shock protein 70 (HSP70).Increased expression of HSP70 has been reported to decrease cell cytotoxicity and apoptosis mediated by TNF-α and oxidative stress.During a malaria infection, monocytes act as the first line of defence and phagocytose infected red blood cells, free parasites and parasite products including the malaria pigment, haemozoin.Monocytes also express and secrete a wide range of cytokines, nitric oxide, reactive oxygen species and phospholipase A2 to combat the infection.A dysregulated expression of cytokines could lead to severe and cerebral malaria.As malaria treatment, antimalarial and antiinflammatory drugs are given to malaria-infected patients.They seem to affect the expression of cytokines including TNF-α and prevent severe/cerebral malaria but the mechanism by which they act is still under debate.It was of interest to study the effects of antimalarial, anti-inflammatory drugs and β-haematin on monocyte HSP70 protein expression during febrile conditions, to see whether they could affect monocyte responses through monocyte HSP70 protein expression.Human HSP70 was recombinantly expressed, affinity-purified and used to raise antibodies against rHSP70 in chickens.Monoclonal antibodies against rHSP70 were made and expressed as single chain variable fragment (scFv), using phage display technology.J774A.1 and U937 monocytes were treated with nine antimalarial drugs, namely artemisinin, artemether, artesunate, chloroquine, quinine, quinacrine, quinidine, primaquine and pyrimethamine and with four antiinflammatory drugs, including danazol, probucol, ambroxol and curcumin at the therapeutic concentration of each drug, then heat shocked.J774A.1 monocytes were fed with β-haematin and latex beads, under feverish conditions.Recombinant antibodies against HSP70 were then used to detect HSP70 protein expression in monocyte lysates.It was found that chloroquine and artemether increased HSP70 protein expression in monocytes, with artemether being the most effective.Artemisinin, quinine, quinidine, quinacrine and primaquine decreased monocyte HSP70 protein expression with quinine and quinacrine being v most effective.Pyrimethamine had no effect on monocyte HSP70 protein expression, and artesunate seemed to increase HSP70 expression in J774A.1 cells, but not significantly.Danazol decreased monocyte HSP70 expression, ambroxol and probucol decreased HSP70 expression in U937 cells, while ambroxol increased HSP70 expression in J774A.1 cells.Curcumin decreased HSP70 expression in J774A.1 cells and increased HSP70 expression in U937 cells.Haemozoin laden monocytes have been reported to lead to a dysregulated production of cytokines, and to suppress the functions of monocytes.Monocytes were incubated with βhaematin, hemin and latex beads to study their effects on HSP70 protein expression during fever conditions and it was found that they all decreased monocyte HSP70 protein expression.The
Author: Kajal. Fowdar
Language: English
Topic: Malaria Research and Control
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2899916070