In vitro assessment of cytokines interactions with Balamuthia mandrillaris using human brain microvascular endothelial cells

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 Balamuthia 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.