TY - JOUR
T1 - In vitro inhibition of protease-activated receptors 1, 2 and 4 demonstrates that these receptors are not involved in an Acanthamoeba castellanii keratitis isolate-mediated disruption of the human brain microvascular endothelial cells
AU - Iqbal, Junaid
AU - Naeem, Komal
AU - Siddiqui, Ruqaiyyah
AU - Khan, Naveed Ahmed
N1 - Publisher Copyright:
© 2014 Elsevier Inc.
PY - 2014/11/1
Y1 - 2014/11/1
N2 - Granulomatous amoebic encephalitis is a rare but serious human disease leading almost always to death. The pathophysiology of amoebic encephalitis is better understood, while events leading to the constitution of brain infection are largely unknown. Traversal of the blood-brain barrier is a key step in amoebae invasion of the central nervous system and facilitated by amoebic extracellular proteases. By using specific inhibitors of protease-activated receptors 1, 2 and 4, here we studied the role of these host receptors in Acanthamoeba castellanii-mediated damage to human brain microvasculature endothelial cells (HBMEC), which constitute the blood-brain barrier. The primary HBMEC were incubated with A. castellanii-conditioned medium in the presence or absence of FR-171113 (selective inhibitor of protease-activated receptor 1), FSLLRY-NH2 (inhibitor of protease-activated receptor 2), and tcY-NH2 (inhibitor of protease-activated receptor 4). The HBMEC monolayer disruptions were assessed by microscopy using Eosin staining, while host cell cytotoxicity was determined by measuring the release of cytoplasmic lactate dehydrogenase. Zymographic assays were performed to determine the effects of inhibitors of protease-activated receptors on the extracellular proteolytic activities of A. castellanii. A. castellanii-conditioned medium produced severe HBMEC monolayer disruptions within 60min. The selective inhibitors of protease-activated receptors tested did not affect HBMEC monolayer disruptions. On the contrary, pre-treatment of A. castellanii-conditioned medium with phenylmethylsulfonyl fluoride, a serine protease inhibitor, or heating for 10min at 95°C abolished HBMEC monolayer disruptions. Additionally, inhibitors of protease-activated receptors tested, failed to block A. castellanii-mediated HBMEC cytotoxicity and did not affect extracellular proteolytic activities of A. castellanii. Protease-activated receptors 1, 2 and 4 do not appear to play a role in A. castellanii-mediated dysfunction of HBMEC, which constitute the blood-brain barrier. The role of additional protease-activated receptors in amoebic invasion of the central nervous system is discussed further.
AB - Granulomatous amoebic encephalitis is a rare but serious human disease leading almost always to death. The pathophysiology of amoebic encephalitis is better understood, while events leading to the constitution of brain infection are largely unknown. Traversal of the blood-brain barrier is a key step in amoebae invasion of the central nervous system and facilitated by amoebic extracellular proteases. By using specific inhibitors of protease-activated receptors 1, 2 and 4, here we studied the role of these host receptors in Acanthamoeba castellanii-mediated damage to human brain microvasculature endothelial cells (HBMEC), which constitute the blood-brain barrier. The primary HBMEC were incubated with A. castellanii-conditioned medium in the presence or absence of FR-171113 (selective inhibitor of protease-activated receptor 1), FSLLRY-NH2 (inhibitor of protease-activated receptor 2), and tcY-NH2 (inhibitor of protease-activated receptor 4). The HBMEC monolayer disruptions were assessed by microscopy using Eosin staining, while host cell cytotoxicity was determined by measuring the release of cytoplasmic lactate dehydrogenase. Zymographic assays were performed to determine the effects of inhibitors of protease-activated receptors on the extracellular proteolytic activities of A. castellanii. A. castellanii-conditioned medium produced severe HBMEC monolayer disruptions within 60min. The selective inhibitors of protease-activated receptors tested did not affect HBMEC monolayer disruptions. On the contrary, pre-treatment of A. castellanii-conditioned medium with phenylmethylsulfonyl fluoride, a serine protease inhibitor, or heating for 10min at 95°C abolished HBMEC monolayer disruptions. Additionally, inhibitors of protease-activated receptors tested, failed to block A. castellanii-mediated HBMEC cytotoxicity and did not affect extracellular proteolytic activities of A. castellanii. Protease-activated receptors 1, 2 and 4 do not appear to play a role in A. castellanii-mediated dysfunction of HBMEC, which constitute the blood-brain barrier. The role of additional protease-activated receptors in amoebic invasion of the central nervous system is discussed further.
KW - Acanthamoeba
KW - Brain endothelial cells
KW - FR-171113
KW - FSLLRY-NH
KW - Protease-activated receptors
KW - TcY-NH
KW - Zymographic assays
UR - http://www.scopus.com/inward/record.url?scp=84912059518&partnerID=8YFLogxK
U2 - 10.1016/j.exppara.2014.03.023
DO - 10.1016/j.exppara.2014.03.023
M3 - Article
C2 - 24703976
AN - SCOPUS:84912059518
SN - 0014-4894
VL - 145
SP - S78-S83
JO - Experimental Parasitology
JF - Experimental Parasitology
IS - S
ER -