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

Mitochondrial dynamics in pulmonary disease: Implications for the potential therapeutics

Mitochondria are dynamic organelles that continuously undergo fusion/fission to maintain normal cell physiological activities and energy metabolism. When mitochondrial dynamics is unbalanced, mitochondrial homeostasis is broken, thus damaging mitochondrial function. Accumulating evidence demonstrates that impairment in mitochondrial dynamics leads to lung tissue injury and pulmonary disease progression in a variety of disease models, including inflammatory responses, apoptosis, and barrier breakdown, and that the role of mitochondrial dynamics varies among pulmonary diseases. These findings suggest that modulation of mitochondrial dynamics may be considered as a valid therapeutic strategy in pulmonary diseases. In this review, we discuss the current evidence on the role of mitochondrial dynamics in pulmonary diseases, with a particular focus on its underlying mechanisms in the development of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis (PF), pulmonary arterial hypertension (PAH), lung cancer and bronchopulmonary dysplasia (BPD), and outline effective drugs targeting mitochondrial dynamics-related proteins, highlighting the great potential of targeting mitochondrial dynamics in the treatment of pulmonary disease.

Revisiting airway epithelial dysfunction and mechanisms in chronic obstructive pulmonary disease: the role of mitochondrial damage

Chronic exposure to environmental hazards causes airway epithelial dysfunction, primarily impaired physical barriers, immune dysfunction, and repair or regeneration. Impairment of airway epithelial function subsequently leads to exaggerated airway inflammation and remodeling, the main features of chronic obstructive pulmonary disease (COPD). Mitochondrial damage has been identified as one of the mechanisms of airway abnormalities in COPD, which is closely related to airway inflammation and airflow limitation. In this review, we evaluate updated evidence for airway epithelial mitochondrial damage in COPD and focus on the role of mitochondrial damage in airway epithelial dysfunction. In addition, the possible mechanism of airway epithelial dysfunction mediated by mitochondrial damage is discussed in detail, and recent strategies related to airway epithelial-targeted mitochondrial therapy are summarized. Results have shown that dysregulation of mitochondrial quality and oxidative stress may lead to airway epithelial dysfunction in COPD. This may result from mitochondrial damage as a central organelle mediating abnormalities in cellular metabolism. Mitochondrial damage mediates procellular senescence effects due to mitochondrial reactive oxygen species, which effectively exacerbate different types of programmed cell death, participate in lipid metabolism abnormalities, and ultimately promote airway epithelial dysfunction and trigger COPD airway abnormalities. These can be prevented by targeting mitochondrial damage factors and mitochondrial transfer. Thus, because mitochondrial damage is involved in COPD progression as a central factor of homeostatic imbalance in airway epithelial cells, it may be a novel target for therapeutic intervention to restore airway epithelial integrity and function in COPD.

Evaluation of Oxidative Stress and Antioxidant Biomarkers in Chronic Cigarette Smokers: A Pilot Study

Introduction The present study was undertaken to assess the status of oxidative stress in chronic cigarette smokers. Materials and methods Thirty adult male chronic cigarette smokers and an equal number of age and sex-matched normal subjects from the Deoghar district of Jharkhand state, India, were included in the study. The status of lipid peroxidation was determined using malondialdehyde (MDA), and the activities of enzymic antioxidants, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), were determined using standard protocols. Results Results showed that the serum MDA levels were significantly increased, and the enzymic antioxidants were markedly decreased in chronic cigarette smokers compared to the normal subjects. Conclusion Our study demonstrated that oxidative stress is more pronounced in cigarette smokers compared to non-smokers. The number of cigarettes smoked plays a crucial role in increasing the reactive oxygen species and decreasing the cellular antioxidants.

Research progress of mitochondria in chronic obstructive pulmonary disease: a bibliometric analysis based on the Web of Science Core Collection

Background

Due to its high morbidity and mortality, chronic obstructive pulmonary disease (COPD) has become a major global healthcare issue. Although there is abundant research regarding COPD, a bibliometric analysis of the literature related to mitochondria and COPD is lacking. Thus this study aimed to summarize the research status, research direction, and research hotspots of the published articles concerning COPD and mitochondria.

Methods

A literature search for included publications related to COPD and mitochondria was carried out on the Web of Science Core Collection from the date of database establishment to December 15, 2022. A subsequent bibliometric and visual analysis of the included publications was conducted via Microsoft Excel, R software, CiteSpace, and VOSviewer.

Results

A total of 227 published articles on COPD and mitochondria from 139 journals were included. Over the study period, the annual publication number and citation frequency in this field both showed a trend of continuous growth. The United States had the highest centrality and was the most productive country. The frequently occurring keywords were "oxidative stress", "obstructive pulmonary disease", "dysfunction", "mitochondria", "inflammation", and "cigarette smoke", among others. Recent research hotspots included autophagy, model, mitochondria, health, and extracellular vesicles (EVs). Despite an abundance and variety of research, there is still relatively little academic communications between scholars and institutions.

Conclusions

This bibliometric study can help researchers gain a quick overview of the research into mitochondria and COPD and thus inform novel ideas and directions for future research in this field.

Mitochondrial damage-associated molecular patterns in chronic obstructive pulmonary disease: Pathogenetic mechanism and therapeutic target

Chronic obstructive pulmonary disease (COPD) is a common inflammatory airway disease characterized by enhanced inflammation. Recent studies suggest that mitochondrial damage-associated molecular patterns (DAMPs) may play an important role in the regulation of inflammation and are involved in a serial of inflammatory diseases, and they may also be involved in COPD. This review highlights the potential role of mitochondrial DAMPs during COPD pathogenesis and discusses the therapeutic potential of targeting mitochondrial DAMPs and their related signaling pathways and receptors for COPD. Research progress on mitochondrial DAMPs may enhance our understanding of COPD inflammation and provide novel therapeutic targets.

Elamipretide alleviates pyroptosis in traumatically injured spinal cord by inhibiting cPLA2-induced lysosomal membrane permeabilization

Spinal cord injury (SCI) is a devastating injury that may result in permanent motor impairment. The active ingredients of medications are unable to reach the affected area due to the blood‒brain barrier. Elamipretide (SS-31) is a new and innovative aromatic cationic peptide. Because of its alternating aromatic and cationic groups, it freely crosses the blood‒brain barrier. It is also believed to decrease inflammation and protect against a variety of neurological illnesses. This study explored the therapeutic value of SS-31 in functional recovery after SCI and its possible underlying mechanism. A spinal cord contusion injury model as well as the Basso Mouse Scale, footprint assessment, and inclined plane test were employed to assess how well individuals could function following SCI. The area of glial scarring, the number of dendrites, and the number of synapses after SCI were confirmed by HE, Masson, MAP2, and Syn staining. Western blotting, immunofluorescence, and enzyme-linked immunosorbent assays were employed to examine the expression levels of pyroptosis-, autophagy-, lysosomal membrane permeabilization (LMP)- and MAPK signalling-related proteins. The outcomes showed that SS-31 inhibited pyroptosis, enhanced autophagy and attenuated LMP in SCI. Mechanistically, we applied AAV vectors to upregulate Pla2g4A in vivo and found that SS-31 enhanced autophagy and attenuated pyroptosis and LMP by inhibiting phosphorylation of cPLA2. Ultimately, we applied asiatic acid (a p38-MAPK agonist) to test whether SS-31 regulated cPLA2 partially through the MAPK-P38 signalling pathway. Our group is the first to suggest that SS-31 promotes functional recovery partially by inhibiting cPLA2-mediated autophagy impairment and preventing LMP and pyroptosis after SCI, which may have potential clinical application value.

SS-31, a Mitochondria-Targeting Peptide, Ameliorates Kidney Disease

Mitochondria are essential for eukaryotic cell activity and function, and their dysfunction is associated with the development and progression of renal diseases. In recent years, there has been a rapid development in mitochondria-targeting pharmacological strategies as mitochondrial biogenesis, morphology, and function, as well as dynamic changes in mitochondria, have been studied in disease states. Mitochondria-targeting drugs include nicotinamide mononucleotide, which supplements the NAD+ pool; mitochondria-targeted protective compounds, such as MitoQ; the antioxidant coenzyme, Q10; and cyclosporin A, an inhibitor of the mitochondrial permeability transition pore. However, traditional drugs targeting mitochondria have limited clinical applications due to their inability to be effectively absorbed by mitochondria in vivo and their high toxicity. Recently, SS-31, a mitochondria-targeting antioxidant, has received significant research attention as it decreases mitochondrial reactive oxygen species production and prevents mitochondrial depolarization, mitochondrial permeability transition pore formation, and Ca²⁺-induced mitochondrial swelling, and has no effects on normal mitochondria. At present, few studies have evaluated the effects of SS-31 against renal diseases, and the mechanism underlying its action is unclear. In this review, we first discuss the pharmacokinetics of SS-31 and the possible mechanisms underlying its protective effects against renal diseases. Then, we analyze its renal disease-improving effects in various experimental models, including animal and cell models, and summarize the clinical evidence of its benefits in renal disease treatment. Finally, the potential mechanism underlying the action of SS-31 against renal diseases is explored to lay a foundation for future preclinical studies and for the evaluation of its clinical applications.

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

Exposure of the airways epithelium to environmental insults, including cigarette smoke, results in increased oxidative stress due to unbalance between oxidants and antioxidants in favor of oxidants. Oxidative stress is a feature of inflammation and promotes the progression of chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). Increased oxidative stress leads to exhaustion of antioxidant defenses, alterations in autophagy/mitophagy and cell survival regulatory mechanisms, thus promoting cell senescence. All these events are amplified by the increase of inflammation driven by oxidative stress. Several models of bronchial epithelial cells are used to study the molecular mechanisms and the cellular functions altered by cigarette smoke extract (CSE) exposure, and to test the efficacy of molecules with antioxidant properties. This review offers a comprehensive synthesis of human in-vitro and ex-vivo studies published from 2011 to 2021 describing the molecular and cellular mechanisms evoked by CSE exposure in bronchial epithelial cells, the most used experimental models and the mechanisms of action of cellular antioxidants systems as well as natural and synthetic antioxidant compounds.

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

PURPOSE

Obesity is a worldwide metabolic disease and a critical risk factor for several chronic conditions. Obstructive sleep apnea (OSA) is an important complication of obesity. With the soaring morbidity of obesity, the prevalence of OSA has markedly increased. However, the underlying mechanism of the high relevance between obesity and OSA has not been elucidated. This study investigated the effects of obesity on the structure and function of the genioglossus to explore the possible mechanisms involved in OSA combined with obesity.

METHODS

Six-week-old male C57BL/6J mice were fed high-fat diet (HFD, 60% energy) or normal diet (Control, 10% energy) for 16 weeks. The muscle fibre structure and electromyography (EMG) activity of genioglossus were measured. The ultrastructure and function of mitochondrial, oxidative damage and apoptosis in genioglossus were detected by transmission electron microscopy (TEM), qPCR, Western blotting, immunohistochemistry and TUNEL staining. We further studied the influence of palmitic acid (PA) on the proliferation and myogenic differentiation of C2C12 myoblasts, as well as mitochondrial function, oxidative stress, and apoptosis in C2C12 myotubes.

RESULTS

Compared with the control, the number of muscle fibres was decreased, the fibre type was remarkably changed, and the EMG activity had declined in genioglossus. In addition, a HFD also reduced mitochondria quantity and function, induced excessive oxidative stress and increased apoptosis in genioglossus. In vitro, PA treatment significantly inhibited the proliferation and myogenic differentiation of C2C12 myoblasts. Moreover, PA decreased the mitochondrial membrane potential, upregulated mitochondrial reactive oxygen species (ROS) levels, and activated the mitochondrial-related apoptotic pathway in myotubes.

CONCLUSION

Our findings suggest that a HFD caused genioglossus injury in obese mice. The mitochondrial dysfunction and the accompanying oxidative stress were involved in the genioglossus injury, which may provide potential therapeutic targets for OSA with obesity.