Mechano-oxidative coupling by mitochondria induces proinflammatory responses in lung venular capillaries
Hideo Ichimura, … , Andrew C. Issekutz, Jahar Bhattacharya
Hideo Ichimura, … , Andrew C. Issekutz, Jahar Bhattacharya
Published March 1, 2003
Citation Information: J Clin Invest. 2003;111(5):691-699. https://doi.org/10.1172/JCI17271.
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Article Cardiology

Mechano-oxidative coupling by mitochondria induces proinflammatory responses in lung venular capillaries

Abstract

Elevation of lung capillary pressure causes exocytosis of the leukocyte adhesion receptor P-selectin in endothelial cells (ECs), indicating that lung ECs generate a proinflammatory response to pressure-induced stress. To define underlying mechanisms, we followed the EC signaling sequence leading to P-selectin exocytosis through application of real-time, in situ fluorescence microscopy in lung capillaries. Pressure elevation increased the amplitude of cytosolic Ca2+ oscillations that triggered increases in the amplitude of mitochondrial Ca2+ oscillations and in reactive oxygen species (ROS) production. Responses to blockers of the Ca2+ oscillations and of mitochondrial electron transport indicated that the ROS production was Ca2+ dependent and of mitochondrial origin. A new proinflammatory mechanism was revealed in that pressure-induced exocytosis of P-selectin was inhibited by both antioxidants and mitochondrial inhibitors, indicating that the exocytosis was driven by mitochondrial ROS. In this signaling pathway mitochondria coupled pressure-induced Ca2+ oscillations to the production of ROS that in turn acted as diffusible messengers to activate P-selectin exocytosis. These findings implicate mitochondrial mechanisms in the lung’s proinflammatory response to pressure elevation and identify mitochondrial ROS as critical to P-selectin exocytosis in lung capillary ECs.

Authors

Hideo Ichimura, Kaushik Parthasarathi, Sadiqa Quadri, Andrew C. Issekutz, Jahar Bhattacharya

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Detection of ROS in lung venular capillaries. (a) Images show PLA-induce...
Detection of ROS in lung venular capillaries. (a) Images show PLA-induced DCF fluorescence in capillaries following infusion of either vehicle (upper images) or rotenone (lower images). Higher grey levels indicate higher fluorescence intensity. Bar = 10 μm; n = 4. (b) Tracings show time course of responses in single capillaries. Gap in tracing (upper left) shows interruption of imaging during the second pressure challenge. Rotenone (1 μM) and H2O2 (100 μM; upper right) and FCCP (400 nM; lower left) were infused in capillaries. (c) Pressure-induced increase of DCF fluorescence in capillaries treated with NAC (NA, 10 mM), ebselen (EB, 100 μM), and Trolox (TR, 2 mM). *P < 0.05 compared with untreated control. Mean ± SE; n = 3 for each group. (d) Pressure-induced responses of Ca2+mit and Ca2+cyt in capillaries treated with ebselen (100 μM). Control responses were obtained as paired determinations in the pretreatment period. Mean ± SE; n = 3 for each group. (e) Group data show pressure-induced responses in capillaries treated with rotenone (RT, 1 μM), FCCP (FC, 400 nM), ruthenium red (RR, 10 μM), antimycin A (AN, 1 μg/ml), diphenyleneiodonium (DP, 10 μM), allopurinol (AL, 100 μM), and thapsigargin (TG, 2 μM). Control responses were obtained as paired determinations in the pretreatment period. Ruthenium red was given after 0.005% saponin infusion for 1 minute. *Different from control at P < 0.05. Data are presented as mean ± SE; n = 3 for each group.