Mitochondrial‐Targeting Antioxidant SS‐31 Suppresses Airway Inflammation and Oxidative Stress Induced by Cigarette Smoke

Abstract

This study investigated whether the mitochondrial-targeted peptide SS-31 can protect against cigarette smoke- (CS-) induced airway inflammation and oxidative stress in vitro and in vivo. Mice were exposed to CS for 4 weeks to establish a CS-induced airway inflammation model, and those in the experimental group were pretreated with SS-31 1 h before CS exposure. Pathologic changes and oxidative stress in lung tissue, inflammatory cell counts, and proinflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) were examined. The mechanistic basis for the effects of SS-31 on CS extract- (CSE-) induced airway inflammation and oxidative stress was investigated using BEAS-2B bronchial epithelial cells and by RNA sequencing and western blot analysis of lung tissues. SS-31 attenuated CS-induced inflammatory injury of the airway and reduced total cell, neutrophil, and macrophage counts and tumor necrosis factor- (TNF-) α, interleukin- (IL-) 6, and matrix metalloproteinase (MMP) 9 levels in BALF. SS-31 also attenuated CS-induced oxidative stress by decreasing malondialdehyde (MDA) and myeloperoxidase (MPO) activities and increasing that of superoxide dismutase (SOD). It also reversed CS-induced changes in the expression of mitochondrial fission protein (MFF) and optic atrophy (OPA) 1 and reduced the amount of cytochrome c released into the cytosol. Pretreatment with SS-31 normalized TNF-α, IL-6, and MMP9 expression, MDA and SOD activities, and ROS generation in CSE-treated BEAS-2B cells and reversed the changes in MFF and OPA1 expression. RNA sequencing and western blot analysis showed that SS-31 inhibited CS-induced activation of the mitogen-activated protein kinase (MAPK) signaling pathway in vitro and in vivo. Thus, SS-31 alleviates CS-induced airway inflammation and oxidative stress via modulation of mitochondrial function and regulation of MAPK signaling and thus has therapeutic potential for the treatment of airway disorders caused by smoking.

High-Fat Diet-Induced Mitochondrial Dysfunction Promotes Genioglossus Injury – A Potential Mechanism for Obstructive Sleep Apnea with Obesity

“…SS–31 is reported to be an antioxidant targeting mitochondria. 32 , 33 SS–31 treatment significantly reduced the mitochondrial ROS accumulation in C2C12 myotubes induced by PA ( Figure 8A and B ). In addition, compared with the 300 μ M PA-treated group, SS–31 treatment reduced the number of TUNEL-positive cells ( Figure 8C and D ) and downregulated the protein level of cleaved caspase-3 ( Figure 8E and F ), indicating SS–31 could partly alleviate the apoptotic in C2C12 myotubes caused by PA.

Figure 8 PA increased mitochondrial ROS and apoptosis in C2C12 myotubes.

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Cellular and Molecular Signatures of Oxidative Stress in Bronchial Epithelial Cell Models Injured by Cigarette Smoke Extract

“…In this case, the dyes are non-fluorescent when reduced, but become highly fluorescent upon oxidation. The most widely used dye is the 2 ,7 -dichlorofluorescin diacetate (DCFDA) that become oxidized into 2 ,7 -dichlorofluorescein (DCF) by intracellular ROS [11,14,22,26,28,29,32,33,35,42,45,50,68,72,[83][84][85][87][88][89]104]. Other commercially available fluorogenic probes are also available [13,24,69,80].…”

“…Oxidative stress can also be measured indirectly, by analyzing the degree of lipid peroxidation, a phenomenon that occurs in the presence of elevated concentrations of oxidants. Malondialdehyde (MDA) is one of the products of lipid peroxidation, and can be easily detected by colorimetric or fluorometric analysis [28,29,33,39,70,71]. Alternatively, it is possible to measure the levels of 4-hydroxynonenale (4-HNE) protein adducts by ELISA [22,24].…”

“…The activity of NADPH oxidases, responsible for the generation of the anion superoxide through the conversion of NADPH into NADP + , can be examined using an enzymatic assay and colorimetric detection [22]. Myeloperoxidase catalyzes the conversion of H 2 O 2 and chloride (Cl -) to hypochlorous acid (HOCl) and can be detected by using enzymatic/colorimetric assays [13,29].…”

“…Additionally, stimulation of HBEs with CSE leads to activation of MAPKs, which is associated with proliferation, cell survival and motility, and cellular metabolism, and drives stress response and inflammation. More specifically, among MAPKs, activation of c-Jun N-terminal kinase (JNK), p38 and ERK1/2 has been widely described in relation to CSE-induced inflammation [22,27,29,36,46,49,53,74,77,83,86,88,98,[102][103][104]113].…”