Reactive Oxygen Species Inactivation of Surfactant Involves Structural and Functional Alterations to Surfactant Proteins SP-B and SP-C

Abstract

Exposing bovine lipid extract surfactant (BLES), a clinical surfactant, to reactive oxygen species arising from hypochlorous acid or the Fenton reaction resulted in an increase in lipid (conjugated dienes, lipid aldehydes) and protein (carbonyls) oxidation products and a reduction in surface activity. Experiments where oxidized phospholipids (PL) were mixed with BLES demonstrated that this addition hampered BLES biophysical activity. However the effects were only moderately greater than with control PL. These results imply a critical role for protein oxidation. BLES oxidation by either method resulted in alterations in surfactant proteins SP-B and SP-C, as evidenced by altered Coomassie blue and silver staining. Western blot analyses showed depressed reactivity with specific antibodies. Oxidized SP-C showed decreased palmitoylation. Reconstitution experiments employing PL, SP-B, and SP-C isolated from control or oxidized BLES demonstrated that protein oxidation was more deleterious than lipid oxidation. Furthermore, addition of control SP-B can improve samples containing oxidized SP-C, but not vice versa. We conclude that surfactant oxidation arising from reactive oxygen species generated by air pollution or leukocytes interferes with surfactant function through oxidation of surfactant PL and proteins, but that protein oxidation, in particular SP-B modification, produces the major deleterious effects.

Chronic sodium hydrosulfide treatment decreases medial thickening of intramyocardial coronary arterioles, interstitial fibrosis, and ROS production in spontaneously hypertensive rats

“…In recent years, accumulating evidence has suggested that H 2 S plays a pivotal role in cardiovascular regulation (27,16). Intravenous bolus injection of H 2 S [in the form of sodium hydrosulfide (NaHS), a water-soluble H 2 S donor] transiently decreased BP in rats by [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]7). H 2 S has been further shown to dilate rat aortic tissues by opening ATPsensitive potassium channels (K ATP channels) in vascular smooth muscle cells (VSMC) (31).…”

Beneficial effects of synthetic KL4surfactant in experimental lung transplantation

“…The significant decrease of surface adsorption rate of surfactant isolated from untreated transplanted lungs can be explained by the following. 1) Significant increase in lipid peroxides and protein carbonyls in the active surfactant fraction or LA: reactive oxygen species released by activated alveolar macrophages and neutrophils may be involved in surfactant oxidation, which results in structural alterations that lead to poor surface activity [30]. 2) High SA/ LA PL ratio, which suggests accelerated LA to SA conversion, probably as a consequence of structural alterations in oxidised LA.…”

Effect of Serum, Cholesterol and Low Density Lipoprotein on the Functionality and Structure of Lung Surfactant Films

“…Previous mass spectral study of LDL 33 also suggests that the 369 m/z peak is a deoxygenated cholesterol, molecular wt, M.W., of cholesterol -OH 386 -O 16 370 or cholesterol H , and is the major peak. The other major peak at 496 could possibly be fragments of cholesterol ester 33,34 . The calculated number for complete cholesterol ester peak at 671 m/z is very small as well as contained an Na ion and was difficult to detect in MALDI-TOF of LDL 33 .…”

“…The other major peak at 496 could possibly be fragments of cholesterol ester 33,34 . The calculated number for complete cholesterol ester peak at 671 m/z is very small as well as contained an Na ion and was difficult to detect in MALDI-TOF of LDL 33 . A more recent study has shown that cholesterol esters are more potent inhibitors of BLES than free cholesterol 45 .…”

“…This may be due to different surfactant concentrations used in the studies as well as insertion of the proteins in the surfactant dispersions by different methods. However unlike these proteins, cell membrane lipids and free fatty acids, such as oleic acid, are shown to also readily adsorb and penetrate the films and form mixtures with lung surfactant lipids 22,29,33,46 . Previous study on the effects of lysophosphotidylcholine LPC on lung surfactant show that, LPC-induced inhibition of LS due to interactions within the surfactant film during compression.…”