ABSTRACT
Balamuthia mandrillaris is well known to cause fatal Balamuthia amoebic encephalitis [BAE]. Amoebic transmission into the central nervous system [CNS], haematogenous spread is thought to be the prime step, followed by blood-brain barrier [BBB] dissemination. Macrophages are considered to be the foremost line of defense and present in excessive numbers during amoebic infections. The aim of the present investigation was to evaluate the effects of macrophages alone or primed with cytokines on the biological characteristics of Balamuthia in vitro. Using human brain microvascular endothelial cells [HBMEC], which constitutes the BBB, we have shown that Balamuthia demonstrated >90% binding and >70% cytotoxicity to host cells. However, macrophages further increased amoebic binding and Balamuthia-mediated cell cytotoxicity. Furthermore macrophages exhibited no amoebicidal effect against Balamuthia. Zymography assay demonstrated that macrophages exhibited no inhibitory effect on proteolytic activity of Balamuthia. Overall we have shown for the first time macrophages has no inhibitory effects on the biological properties of Balamuthia in vitro. This also strengthened the concept that how and why Balamuthia can cause infections in both immuno-competent and immuno-compromised individuals
ABSTRACT
Acanthamoeba castellanii is member of free living amoeba that may cause painful sight-threatening keratitis and life threatening encephalitis which involves central nervous system. Treatments for both infections are problematic because of the amoebic cysts resistance to therapeutic agents. Here we evaluated in vitro strength of methanolic seed extract of Peganum harmala on Acanthamoeba cysts and its encystment mechanism. Our results revealed seed extracts [1 to 30mg/ml] exhibited amoebicidal effects against Acanthamoeba cysts. Furthermore Acanthamoeba encystment was also inhibited in concentration dependent manner with maximum inhibition at 2 micro g/ml after 48h incubation. In conclusion, we demonstrated for the first time that methanolic extracts exhibit remarkable inhibition of Acanthamoeba cysts and encystment in vitro which could serve a potential new natural agent against Acanthamoeba
ABSTRACT
Balamuthia amoebic encephalitis [BAE] is a life threatening human disease which, always lead to death. Amoebae invasion of the bloodstream is considered an important step in BAE followed by their haematogenous spread. It is more likely that Balamuthia mandrillaris enters into the central nervous system through blood-brain barrier [BBB] sites. The objective of the present study was to determine the impact of cytokines on biological properties of alamuthia in vitro. Human brain microvascular endothelial cells [HBMEC], which constitutes the BBB were used in vitro test model for the present investigation. It was observed that Balamuthia exhibited >90% binding and >70% cytotoxicity to HBMEC. However, cytokines did not affect amoebic binding and cytotoxicity except lipopolysaccharide [LPS] which reduced Balamuthia-mediated HBMEC cytotoxicity. It is also important to note that amoebic numbers were reduced in the presence of LPS within 24 h. We have shown previously the bacterial uptake by Balamuthia is very limited which is further investigated in the presence of cytokines and observed a slight reduction of bacterial uptake during phagocytosis assay. Zymography assays revealed there is no effect of cytokines on proteolytic activity of Balamuthia. Overall we described for the first time that cytokines has no inhibitory effects on biological properties of Balamuthia in vitro.