|GOEIJENBIER, MARCO - Erasmus Medical Center|
|GASEM, M - Diponegoro University|
|MEIJERS, JOOST - University Of Amsterdam|
|HARTSKEERL, RUDY - Royal Tropical Institute|
|AHMED, AHMED - Royal Tropical Institute|
|GORIS, MARGA - Royal Tropical Institute|
|ISBANDRIO, BAMBANG - Diponegoro University|
|SCHULLER, SIMONE - University Of Bern|
|OSTERHAUS, ALBERT - Erasmus Medical Center|
|MARTINA, BYRON - Erasmus Medical Center|
|VAN GORP, ERIC - Erasmus Medical Center|
|WAGENAAR, JIRI - Erasmus Medical Center|
Submitted to: Journal of Infection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2015
Publication Date: 6/3/2015
Citation: Goeijenbier, M., Gasem, M.H., Meijers, J.C., Hartskeerl, R.A., Ahmed, A., Goris, M.G., Isbandrio, B., Schuller, S.S., Osterhaus, A., Martina, B.E., Van Gorp, E.C., Nally, J.E., Wagenaar, J.F. 2015. Markers of endothelial cell activation and immune activation are increased in patients with severe leptospirosis and associated with disease severity. Journal of Infection. DOI: 10.1016/j.jinf.2015.05.016.
Interpretive Summary: Leptospirosis causes a wide range of clinical manifestations that range from a mild fever, to the more severe icteric form of leptospirosis, to leptospiral pulmonary haemorrhagic syndrome. Pulmonary leptospirosis is associated with high mortality rates and hypothesized to be mediated, at least in part, by the host immune response. Since the endothelium is a key player in the regulation of hemostasis, endothelial cell dysfunction was examined in a cohort of leptospirosis patients, in combination with in vitro cell models, to determine their collective response to infection with Leptospira. Soluble E-selectin (sE-selectin) and von Willebrand factor (VWF), markers of activity expressed on the surface of endothelial cells, were elevated in patients with severe leptospirosis. Increased levels of VWF were also detected when an in vitro model of endothelial cells was incubated with pathogenic leptospires but levels of E-selectin did not change. However, the in vitro model detected leptospires within the endothelial cells where they appeared to be actively replicating. These results prompted an examination of alternative markers of the host immune response in patients with severe leptospirosis, such as soluble IL-2r (sIL-2r), a marker of T-cell activation. Levels of sIL-2r were increased in patients that developed bleeding and significantly correlated to duration of hospital stay. Collectively, these results indicate that endothelial cell dysfunction and the host immune response mediate, in part, pulmonary leptospirosis.
Technical Abstract: Objectives: Previous studies concluded that haemorrhage is one of the most accurate prognostic factors of mortality in leptospirosis. Therefore, endothelial cell activation was investigated in relation to disease severity in severe leptospirosis. Methods: Prospective cohort study of severe leptospirosis patients. Plasma levels of sE-selectin and Von Willebrand factor (VWF) were determined. Consequently, an in vitro endothelial cell model was used to assess endothelial activation after exposure to virulent Leptospira. Finally, immune activation, as a potential contributing factor to endothelial cell activation, was determined by soluble IL2-receptor (sIL-2r) and soluble Fas-ligand (sFasL) levels. Results: Plasma levels of sE-selectin and VWF strongly increased in patients compared to healthy controls. Furthermore, sE-selectin was significantly elevated (203 ng/ml vs. 157 ng/ml, p < 0.05) in survivors compared to non-survivors. Endothelial cells exposed to virulent Leptospira showed increased VWF expression. E-selectin and ICAM-1 expression did not change. Immunohistochemistry revealed the presence of intracellular Leptospira and qPCR suggested replication. In vivo analysis showed that increased levels of sFasL and sIL-2r were both strongly associated with mortality. Furthermore sIL-2r levels were increased in patients that developed bleeding and significantly correlated to duration of hospital stay. Discussion: Markers of endothelial activation and immune activation were associated with disease severity in leptospirosis patients.