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Peroxynitrite‐mediated damage during rickettsial infection of human microvascular endothelial cells
Author(s) -
Woods Michael Edward,
Wen Gary,
Olano Juan P.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.lb116-c
Subject(s) - nitric oxide , peroxynitrite , propidium iodide , intracellular , chemistry , endothelium , endothelial stem cell , rickettsia , apoptosis , biophysics , microbiology and biotechnology , programmed cell death , immunology , biology , biochemistry , in vitro , endocrinology , enzyme , superoxide , virus , organic chemistry
The objective of this study was to determine the effects of nitric oxide and it's by‐products on rickettsiae‐infected human endothelial cells. The HMEC‐1 cell line was infected with Rickettsia conorii and treated with or without the nitric oxide donor, DETA NONoate and the peroxynitrite decomposition catalyst FeTMPyP. Electrical resistance of the endothelial monolayers was monitored by Electric Cell‐substrate Impedance Sensing as a measurement of paracellular permeability. Rickettsial viability was measured by quantitative real‐time PCR and host cell viability was measured using propidium iodide staining. The results show that high levels (500uM) of the nitric oxide donor result in a rapid decrease in electrical resistance after the first day of infection and treatment. Lower levels (100uM) however proved to delay the onset of rickettsiae‐induced cell death without causing a significant loss of monolayer integrity. Interestingly, both doses of the nitric oxide donor were equally effective at decreasing the number of viable intracellular rickettsiae. Additionally, we noticed that cell death did not correlate with the decrease in electrical resistance across the monolayers. Finally, we observed that the addition of FeTMPyP appeared to reverse the effects of high levels of the nitric oxide donor and the monolayers appeared to behave more similar to non‐treated, infected cells. We have demonstrated that exogenously added nitric oxide has the ability to negatively impact the integrity of the microvascular endothelium most probably through a peroxynitrite‐dependent mechanism.