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EXOCYTOSIS OF ENDOTHELIAL LYSOSOME‐RELATED ORGANELLES HAIR‐TRIGGERS A PATCHY LOSS OF GLYCOCALYX AT THE ONSET OF SEPSIS
Author(s) -
Zullo Joseph A,
Fan Jie,
Azar Tala,
Yen Wanyi,
Zeng Min,
Chen Jun,
Ratliff Brian,
Song Jun,
Tarbell John M,
Goligorsky Michael S,
Fu Bingmei
Publication year - 2016
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.30.1_supplement.745.2
Subject(s) - exocytosis , lysosome , glycocalyx , microbiology and biotechnology , vacuole , organelle , video microscopy , confocal microscopy , motility , chemistry , secretion , biology , biochemistry , cytoplasm , enzyme
Endothelial surface glycocalyx (ESG) is a well‐known regulator of leukocyte surveillance, vascular permeability, and a sensor of shear stress. ESG is degraded during sepsis, thus contributing to systemic multiorgan involvement. Our previous demonstration of a very early post‐stress exocytosis of lysosome‐related organelles (LRO) with their lytic enzymes led us to hypothesize that exocytosis of LRO may catapult a synchronized degradation of ESG. Methods and Results To test this hypothesis we first analyzed the time‐course of exocytosis of Weibel‐Palade bodies and secretory lysosomes after application of lipopolysaccharides (LPS) to endothelial cells. Time‐lapse video microscopy revealed that LROs undergo agitation and vectorial movement with a time course of a few minutes after LPS. In addition, spectrophotometry measurements illustrated an increase of lysosomal cargo, cathepsin B, within the media after 10min of LPS exposure. Two therapeutic maneuvers, a nitric oxide intermediate, NG‐hydroxy‐L‐arginine (NOHA), and culture media conditioned by endothelial progenitor cells (EPC‐CM) reduced the directionality and motility of LRO. The patchy loss of ESG occurring with the similar fast kinetics was confirmed using confocal fluorescence microscopy and Stochastic Optical Reconstruction Microscopy. The loss of ESG was blunted by pretreatment with NOHA or EPC‐CM. Moreover, these treatments resulted in a significant reduction of mortality of septic mice. Conclusion In summary, above studies provide the first demonstration of the very early patchy disintegration of ESG which can be prevented by pretreatment with NOHA and EPC‐CM, maneuvers that reduced exocytosis of LRO. Data support the hypothesis assigning to stress‐induced exocytosis of these organelles the role of a hair‐trigger for local degradation of ESG that in turn initiates leukocyte infiltration, increase in vascular permeability, and partially accounts for the later morbidity and mortality. Support or Funding Information NIH grants DK54602, DK052783 and DK45462 (MSG), SC1CA153325 (BMF) and R01HL094889 (JMT and BMF); AHA grant 12SDG9080006 and ASN grant 010973‐101 (BBR); and The New York Community Trust ‐ Renal Clinical Fund (BBR)