Dual role of autophagy/mitophagy in chronic obstructive pulmonary disease

A multi-omics approach identifies the key role of disorders of sphingolipid metabolism in Ang II-induced hypertensive cardiomyopathy myocardial remodeling

Hypertension-induced myocardial remodelling encompasses both structural and functional changes in cardiac muscle tissue, such as myocardial hypertrophy, fibrosis, and inflammation. These alterations not only impair the systolic and diastolic functions of the heart but also elevate the risk of cardiovascular events and heart failure. One of the primary contributors to hypertensive cardiomyopathy (HTN-CM) is the over-activation of the renin-angiotensin-aldosterone system (RAAS), which subsequently induces myocardial remodeling. Although conventional therapeutic strategies aim to suppress RAAS and slow the progression of heart failure, the primary challenge in treating HTN-CM remains the lack of sensitive and specific biomarkers for early detection of myocardial remodelling. Combined multi-omics analyses, complemented by experimental validation, offer a systematic understanding of the landscape of gene/protein/metabolite expression in HTN-CM, revealing the underlying mechanisms of angiotensin II (Ang II)-induced myocardial remodeling in HTN-CM. Transcriptomic analysis revealed that differentially expressed genes (DEGs) are implicated in sphingolipid metabolic processes and are associated with collagen synthesis and inflammatory responses, collectively contributing to myocardial remodeling in HTN-CM. Proteomic analysis demonstrated that differentially expressed proteins (DEPs) are also involved in inflammatory and fibrotic processes, with associations to sphingolipid signaling pathways, particularly manifested through elevated expression of IL6, COL4A1, FGG, FGB, CREBBP and SPHK2 proteins. Metabolomic profiling further elucidated the increased expression of bioactive sphingolipid metabolites S1P and Sa1P in the myocardium of HTN-CM. Integrative multi-omics analysis revealed that HTN-CM is primarily influenced by the sphingolipid signaling pathway, with additional associations to the HIF-1α and FoxO signaling pathways. Correlation analysis has highlighted strong associations between sphingolipids and genes/proteins related to fibrosis and inflammation, as well as their connection to the HIF-1α and FoxO signalling pathways. Furthermore, certain key indicators were validated through ELISA and Western blot analyses in both plasma and myocardial tissue. In conclusion, the findings of this study suggest that excessive Ang II may induce abnormalities in sphingolipid metabolism, resulting in increased levels of S1P in both circulating and myocardial tissues. This elevation in S1P is implicated in myocardial inflammatory and fibrotic alterations, highlighting its pivotal role in myocardial remodeling. The specific mechanism underlying the sphingolipid signaling pathway in myocardial remodeling may involve downstream biological processes, including oxidative stress and excessive mitochondrial autophagy, mediated by HIF-1α and FoxO.

OSGIN1 regulates PM2.5-induced fibrosis via mediating autophagy in an in vitro model of COPD

Fine particulate matter (PM2.5) has been identified as a significant contributing factor to the exacerbation of chronic obstructive pulmonary disease (COPD). It has been observed that PM2.5 may induce lung fibrosis in COPD, although the precise molecular mechanism behind this remains unclear. In a previous study, we demonstrated that PM2.5 upregulates oxidative stress induced growth inhibitor 1 (OSGIN1), which in turn leads to injury in airway epithelial cells, thereby, suggesting a potential link between PM2.5 exposure and COPD. Based on this, we hypothesized that OSGIN1 plays a role in PM2.5-induced fibrosis in COPD. Human bronchial epithelial cells (HBEs) were treated with cigarette smoke extract (CSE) to construct an in vitro model of COPD. Our findings revealed that PM2.5 increased fibrosis indicators and upregulated OSGIN1 in CSE-stimulated HBEs (CSE-HBEs), and knockdown of OSGIN1 reduced the expression of fibrosis indicators. Through the use of microRNA target prediction software and the Gene Expression Omnibus database, we predicted miRNAs that targeted OSGIN1 in COPD. Subsequently, real-time polymerase chain reaction and western blot analysis confirmed that PM2.5 modulated miR-654-5p to regulate OSGIN1 in CSE-HBEs. Western blot demonstrated that OSGIN1 induced autophagy, thereby exacerbating fibrosis in CSE-HBEs. In summary, our results suggest that PM2.5 upregulates OSGIN1 through inhibiting miR-654-5p, leading to increased autophagy and fibrosis in CSE-HBEs.

Mechanism of cigarette smoke in promoting small airway remodeling in mice via STAT 3 / PINK 1-Parkin / EMT

BACKGROUND

Airway remodeling is an important pathological of airflow limitation in chronic obstructive pulmonary disease (COPD).However,its mechanism still needs to be further clarify.

METHODS

Animals:Healthy male C57BL/6 mice aged 4-6 weeks were randomly divided into control group and cigarette smoke(CS)group. Mice in the CS group were placed in a homemade glass fumigator, 5 cigarettes/time, 40 min/time, 4 times/day, 5 days/week, for 24 weeks. Mice in the control group were placed in a normal air environment.Cells:BEAS-2B cells were stimulated with 0.1%cigarette smoke extract(CSE).HE staining, immunohistochemical staining and Masson staining were used to observe the pathological of lung tissues, transmission electron microscopy was used to observe the structural of mitochondria in bronchial epithelial cells.Western blotting was used to detect the expression of STAT3,transforming growth factor-β1(TGF-β1),microtubule-associated protein 1A/1B-light chain3(LC3),PINK1,Parkin,E-cadherin,zonula occludens1(ZO-1),vimentin and snail family transcriptional inhibitor1 (Snail1),and MitoSOX Red was used to detect mitochondrial reactive oxygen species(mtROS).

RESULTS

CS exposure causes lung parenchymal destruction and airway remodeling in mice.Compared to the control group,the expression of p-STAT3,TGF-β1 and EMT in the whole lung homogenate of the CS group was increased.Mitochondrial architecture disruption in bronchial epithelial cells of CS mice, with impaired PINK1-Parkin-dependent mitophagy.In vitro experiments showed that CSE exposure led to STAT3 activation, increased TGF-β1,EMT and enhanced PINK1-Parkin-mediated mitophagy.STAT3 inhibition reversed TGF-β1 upregulation induced by CSE and improved CSE-induced EMT and mitophagy.Inhibition of mitophagy improves EMT induced by CSE. Inhibition of mitophagy reduces STAT3-induced EMT.

CONCLUSION

CS activates the STAT3,and activated STAT3 promotes EMT in bronchial epithelial cells by enhancing PINK1-Parkin-mediated mitophagy and TGF-β1 signaling.Moreover, activated STAT3 can promote EMT directly.This may be one of the mechanisms by which CS causes small airway remodeling in COPD.

MKK3 depletion attenuates intestinal injury after traumatic hemorrhagic shock by restoring mitochondrial function

BACKGROUND

Traumatic hemorrhagic shock (THS) is a complex pathophysiological process resulting in multiple organ failure. Intestinal barrier dysfunction is one of the mechanisms implicated in multiple organ failure. The present study aimed to explore the regulatory role of mitogen-activated protein kinase kinase 3 (MKK3) in THS-induced intestinal injury and to elucidate its potential mechanism.

METHODS

Rats were subjected to trauma and hemorrhage to establish a THS animal model. MKK3-targeted lentiviral vectors were injected via the tail vein 72 h before modeling. Twelve hours post-modeling, the mean arterial pressure (MAP) and heart rate (HR) were monitored, and histological injury to the intestine was assessed via H&E staining and transmission electron microscopy. Mitochondrial function and mitochondrial reactive oxygen species (ROS) were evaluated. IEC-6 cells were exposed to hypoxia to mimic intestinal injury following THS in vitro.

RESULTS

MKK3 deficiency alleviated intestinal injury and restored mitochondrial function in intestinal tissues from THS-induced rats and hypoxia-treated IEC-6 cells. In addition, MKK3 deficiency promoted Sirt1/PGC-1α-mediated mitochondrial biogenesis and restricted Pink1/Parkin-mediated mitophagy in the injured intestine and IEC-6 cells. Furthermore, the protective effect of MKK3 knockdown against hypoxia-induced mitochondrial damage was strengthened upon simultaneous LC3B/Pink1/Parkin knockdown or weakened upon simultaneous Sirt1 knockdown.

CONCLUSION

MKK3 deficiency protected against intestinal injury induced by THS by promoting mitochondrial biogenesis and restricting excessive mitophagy.

TROP2 promotes PINK1-mediated mitophagy and apoptosis to accelerate the progression of senile chronic obstructive pulmonary disease by up-regulating DRP1 expression

Chronic obstructive pulmonary disease (COPD) is a chronic airway inflammatory disease characterised by irreversible airflow limitation. The elderly are a vulnerable population for developing COPD. With the growth of age, physiological degenerative changes occur in the thorax, bronchus, lung and vascular wall, which can lead to age-related physiological attenuation of lung function in the elderly, so the prevalence of COPD increases with age. Its pathogenesis has not yet been truly clarified. Mitophagy plays an important role in maintaining the stability of mitochondrial function and intracellular environment by scavenging damaged mitochondria. Currently, studies have shown that trophoblast antigen 2 (TROP2) expression is up-regulated in airway basal cells of patients with COPD, suggesting that TROP2 is involved in the progression of COPD. However, whether it is involved in disease progression by regulating mitochondrial function remains unclear. In this study, compared with non-smoking non-COPD patients, the expression of TROP2 in lung tissues of smoking non-COPD patients and patients with COPD increased, and TROP2 expression in patients with COPD was higher than that in smoking non-COPD patients. To further explore the role of TROP2, we stimulated BEAS-2B with cigarette smoke to construct an in vitro model. We found that TROP2 expression increased, whereas TROP2 silencing reversed the cigarette smoke extract-induced decrease in mitochondrial membrane potential, increased reactive oxygen species content, decreased adenosine triphosphate (ATP) production, increased inflammatory factor secretion and increased apoptosis. In addition, we searched online bioinformatics and screened the gene dynamin-related protein 1 (DRP1) related to mitophagy as the research object. Co-IP assay verified the binding relationship between DRP1 and TROP2. Further study found that TROP2 promoted mitophagy and apoptosis of BEAS-2B cells by up-regulating the expression of DRP1. In addition, PTEN-induced putative kinase 1 (PINK1) is a potential binding protein of DRP1, and DRP1 accelerated mitophagy and apoptosis of BEAS-2B cells by promoting the expression of PINK1. We established a COPD SD rat model by cigarette smoke exposure and LPS instillation and treated it by intraperitoneal injection of si-TROP2. The results showed that TROP2 silencing restored lung function and reduced the secretion of inflammatory factors in bronchoalveolar lavage fluid. In conclusion, TROP2 can be used as a new reference for COPD treatment.

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.

Impaired autophagy in the lower airways and lung parenchyma in stable COPD

Background

There is increasing evidence of autophagy activation in COPD, but its role is complex and probably regulated through cell type-specific mechanisms. This study aims to investigate the autophagic process at multiple levels within the respiratory system, using different methods to clarify conflicting results reported so far.

Methods

This cross-sectional study was performed on bronchial biopsies and peripheral lung samples obtained from COPD patients (30 and 12 per sample type, respectively) and healthy controls (25 and 22 per sample type, respectively), divided by smoking history. Subjects were matched for age and smoking history. We analysed some of the most important proteins involved in autophagosome formation, such as LC3 and p62, as well as some molecules essential for lysosome function, such as lysosome-associated membrane protein 1 (LAMP1). Immunohistochemistry was used to assess the autophagic process in both sample types. ELISA and transcriptomic analysis were performed on lung samples.

Results

We found increased autophagic stimulus in smoking subjects, regardless of respiratory function. This was revealed by immunohistochemistry through a significant increase in LC3 (p<0.01) and LAMP1 (p<0.01) in small airway bronchiolar epithelium, alveolar septa and alveolar macrophages. Similar results were obtained in bronchial biopsy epithelium by evaluating LC3B (p<0.05), also increased in homogenate lung tissue using ELISA (p<0.05). Patients with COPD, unlike the others, showed an increase in p62 by ELISA (p<0.05). No differences were found in transcriptomics analysis.

Conclusions

Different techniques, applied at post-transcriptional level, confirm that cigarette smoke stimulates autophagy at multiple levels inside the respiratory system, and that autophagy failure may characterise COPD.

AP39 inhibits ferroptosis by inhibiting mitochondrial autophagy through the PINK1/parkin pathway to improve myocardial fibrosis with myocardial infarction

BACKGROUND AND PURPOSE

Research has revealed the involvement of mitochondrial autophagy and iron death in the pathogenesis of myocardial fibrosis. The objective of this study is to investigate whether the mitochondrial-targeted H2S donor AP39 inhibits mitochondrial autophagy and antagonizes myocardial cell iron death through the PINK1/Parkin pathway, thereby improving myocardial fibrosis in rats with myocardial infarction.

EXPERIMENTAL APPROACH

A rat model of myocardial infarction was created by intraperitoneal injection of a high dose of isoproterenol, and H9c2 myocardial cells were subjected to hypoxic injury induced by CoCl2. Western blot, RT-PCR, transmission electron microscopy, immunohistochemistry, as well as echocardiography, and studies on isolated hearts were employed.

KEY RESULTS

In the hearts of rats with myocardial infarction, there was a significant accumulation of interstitial collagen fibers, accompanied by downregulation of CSE protein expression, activation of the PINK1/Parkin signaling pathway, and activation of mitochondrial autophagy. Intervention with AP39 resulted in a significant improvement of the aforementioned changes, which could be reversed by the addition of PAG. Similar results were observed in vitro experiments. Furthermore, the addition of CCCP reversed the antagonistic effect of AP39 on myocardial cell iron death, while the addition of RSL3 reversed the inhibitory effect of AP39 on collagen production in myocardial cells.

CONCLUSION AND IMPLICATIONS

The mitochondrial-targeted H2S donor AP39 can inhibit mitochondrial autophagy through the PINK1/Parkin pathway, antagonize myocardial cell iron death, and improve myocardial fibrosis in rats with myocardial infarction.

Autophagy/Mitophagy in Airway Diseases: Impact of Oxidative Stress on Epithelial Cells

Autophagy is the key process by which the cell degrades parts of itself within the lysosomes. It maintains cell survival and homeostasis by removing molecules (particularly proteins), subcellular organelles, damaged cytoplasmic macromolecules, and by recycling the degradation products. The selective removal or degradation of mitochondria is a particular type of autophagy called mitophagy. Various forms of cellular stress (oxidative stress (OS), hypoxia, pathogen infections) affect autophagy by inducing free radicals and reactive oxygen species (ROS) formation to promote the antioxidant response. Dysfunctional mechanisms of autophagy have been found in different respiratory diseases such as chronic obstructive lung disease (COPD) and asthma, involving epithelial cells. Several existing clinically approved drugs may modulate autophagy to varying extents. However, these drugs are nonspecific and not currently utilized to manipulate autophagy in airway diseases. In this review, we provide an overview of different autophagic pathways with particular attention on the dysfunctional mechanisms of autophagy in the epithelial cells during asthma and COPD. Our aim is to further deepen and disclose the research in this direction to stimulate the develop of new and selective drugs to regulate autophagy for asthma and COPD treatment.

Research progress of sophoridine's pharmacological activities and its molecular mechanism: an updated review

Background: Sophoridine, the major active constituent of Sophora alopecuroides and its roots, is a bioactive alkaloid with a wide range of pharmacological effects, including antitumor, anti-inflammatory, antiviral, antibacterial, analgesic, cardioprotective, and immunoprotective activities. Sophora flavescens Aiton is a traditional Chinese medicine that is bitter and cold. Additionally, it also exhibits the effects of clearing heat, eliminating dampness, and expelling insects. Aims of the study: To summarize the pharmacological research and associated mechanisms of sophoridine, we compiled this review by combining a huge body of relevant literature. Materials and methods: The information related to this article was systematically collected from the scientific literature databases including PubMed, Google Scholar, Web of Science, Science Direct, Springer, China National Knowledge Infrastructure, published books, PhD and MS dissertations. Results: Its antitumor activity is particularly remarkable, as it can inhibit cancer cell proliferation, invasion, and metastasis while inducing cell cycle arrest and apoptosis. Additionally, sophoridine also holds therapeutic potential for myocardial ischemia, osteoporosis, arrhythmias, and neurological disorders, primarily through the suppression of related inflammatory factors and cell apoptosis. However, sophoridine has also exhibited adverse effects such as hepatotoxicity and neurotoxicity. The antidisease effect and mechanism of sophoridine are diverse, so it has high research value. Conclusion: As an important traditional Chinese medicine alkaloid, modern pharmacological studies have demonstrated that sophoridine has prominent bioactivities, especially on anti-tumor anti-inflammation activities, and cardiovascular system protection. These activities provide prospects for novel drug development for cancer and some chronic diseases. Nevertheless, the understanding of the multitarget network pharmacology, long-term in vivo toxicity, and clinical efficacy of sophoridine require further detailed research.

Smoking-Associated Exposure of Human Primary Bronchial Epithelial Cells to Aldehydes: Impact on Molecular Mechanisms Controlling Mitochondrial Content and Function

Chronic obstructive pulmonary disease (COPD) is a devastating lung disease primarily caused by exposure to cigarette smoke (CS). During the pyrolysis and combustion of tobacco, reactive aldehydes such as acetaldehyde, acrolein, and formaldehyde are formed, which are known to be involved in respiratory toxicity. Although CS-induced mitochondrial dysfunction has been implicated in the pathophysiology of COPD, the role of aldehydes therein is incompletely understood. To investigate this, we used a physiologically relevant in vitro exposure model of differentiated human primary bronchial epithelial cells (PBEC) exposed to CS (one cigarette) or a mixture of acetaldehyde, acrolein, and formaldehyde (at relevant concentrations of one cigarette) or air, in a continuous flow system using a puff-like exposure protocol. Exposure of PBEC to CS resulted in elevated IL-8 cytokine and mRNA levels, increased abundance of constituents associated with autophagy, decreased protein levels of molecules associated with the mitophagy machinery, and alterations in the abundance of regulators of mitochondrial biogenesis. Furthermore, decreased transcript levels of basal epithelial cell marker KRT5 were reported after CS exposure. Only parts of these changes were replicated in PBEC upon exposure to a combination of acetaldehyde, acrolein, and formaldehyde. More specifically, aldehydes decreased MAP1LC3A mRNA (autophagy) and BNIP3 protein (mitophagy) and increased ESRRA protein (mitochondrial biogenesis). These data suggest that other compounds in addition to aldehydes in CS contribute to CS-induced dysregulation of constituents controlling mitochondrial content and function in airway epithelial cells.

Targeting the mitochondria in chronic respiratory diseases

Mitochondria are one of the basic essential components for eukaryotic life survival. It is also the source of respiratory ATP. Recently published studies have demonstrated that mitochondria may have more roles to play aside from energy production. There is an increasing body of evidence which suggest that mitochondrial activities involved in normal and pathological states contribute to significant impact to the lung airway morphology and epithelial function in respiratory diseases such as asthma, COPD, and lung cancer. This review summarizes the pathophysiological pathways involved in asthma, COPD, lung cancer and highlights potential treatment strategies that target the malfunctioning mitochondria in such ailments. Mitochondria are responsive to environmental stimuli such as infection, tobacco smoke, and inflammation, which are essential in the pathogenesis of respiratory diseases. They may affect mitochondrial shape, protein production and ultimately cause dysfunction. The impairment of mitochondrial function has downstream impact on the cytosolic components, calcium control, response towards oxidative stress, regulation of genes and proteins and metabolic activities. Several novel compounds and alternative medicines that target mitochondria in asthma and chronic lung diseases have been discussed here. Moreover, mitochondrial enzymes or proteins that may serve as excellent therapeutic targets in COPD are also covered. The role of mitochondria in respiratory diseases is gaining much attention and mitochondria-based treatment strategies and personalized medicine targeting the mitochondria may materialize in the near future. Nevertheless, more in-depth studies are urgently needed to validate the advantages and efficacy of drugs that affect mitochondria in pathological states.

Ambient ozone exposure induces ROS related-mitophagy and pyroptosis via NLRP3 inflammasome activation in rat lung cells

OBJECTIVE

To study the regulatory relationship between ozone-induced mitophagy and pyroptosis in lung epithelial cells.

RESULTS

First, type I primary alveolar epithelial cells and male Wistar rats were treated with ozone at different dosages. The ATP content and mitochondrial membrane potential significantly decreased in type I primary alveolar epithelial cells. The mitophagy-related markers and PINK1/Parkin pathway-related proteins, and the co-localization of LC3, Parkin, and mitochondria in type I alveolar epithelial cells indicated that ozone exposure triggered mitophagy. On the other hand, the reactive oxygen species (ROS) inhibitor NAC could significantly alleviate mitophagy in epithelial cells. After treatment with the mitophagy inhibitor MDIVI-1, the levels of the NLRP3 inflammasome, cleaved caspase-1, and N-gasdermin D (N-GSDMD) significantly decreased in the cells. Altogether, these results indicated that mitophagy can be triggered by ozone exposure, and subsequently induces cell death mediated by the NLRP3 inflammasome. Finally, the overexpression and knockdown of NLRP3 confirmed this conclusion.

CONCLUSION

Ozone exposure induced oxidative damage, leading to mitochondrial structural and functional damage. Ozone-induced ROS triggered mitophagy through the activation of the PINK1/Parkin signaling pathway, then pyroptosis through activation of the NLRP3 inflammasome.

Involvement of NEAT1/PINK1-mediated mitophagy in chronic obstructive pulmonary disease induced by cigarette smoke or PM2.5

Background

This study sought to explore the underlying mechanism of long non-coding ribonucleic acid nuclear enriched abundant transcript 1 (NEAT1) and PTEN-induced kinase 1 (PINK1)-mediated mitophagy in chronic obstructive pulmonary disease (COPD) induced by cigarette smoke (CS) or fine particular matter (PM_2.5).

Methods

In total, 30 male Wistar Rats were divided into the following 3 groups: (I) the COPD group exposed to CS (CSM); (II) the COPD group exposed to PM_2.5 (PMM); and (III) the control (Ctrl) group. Pulmonary function, the enzyme-linked immunoassay analysis results, the histopathology results, and the ultrastructures of the lung tissues were examined in the 3 groups, and NEAT1 expression levels and the mitophagy-related protein PINK1, Parkin, LC3B, and p62 levels were assessed by quantitative reverse transcription PCR (RT-qPCR) and Western blotting. The A549 cells were transfected with small interfering ribonucleic acid (siRNA) targeting NEAT1, and subsequently stimulated with CS extract (CSE) and PM_2.5 suspension (PMS). Mitochondrial dysfunction and enhanced mitophagy were observed, and the expression of the NEAT1/PINK1 pathway was assessed by RT-qPCR and Western blotting.

Results

Both the CSM and PMM groups had a lower tidal volume (V_T), minute ventilation (MV), and a higher respiratory rate (f) than the Ctrl group. The interleukin (IL)-6, IL-8, and tumor necrosis factor-alpha levels in the serum and bronchoalveolar lavage fluid of the CSM and PMM groups were significantly increased. The histological examination results revealed airway remodeling, the formation of pulmonary bullae, and emphysema in the CSM and PMM groups. Subsequently, the ultrastructures of the lung tissues in the CSM and PMM groups showed mitochondrial swelling and autophagosomes. Additionally, NEAT1 expression, the level of the mitophagy-related protein PINK1, Parkin, and the ratio of LC3-II/I increased synchronously. Further, NEAT1 siRNA blocked PINK1 expression, inhibited mitochondrial dysfunctions, and mitophagy activation in the A549 cells exposed to CSE or PMS.

Conclusions

Our results suggest that CS and PM_2.5 exposure induce mitochondrial dysfunction, and the NEAT1/PINK1 pathway plays a critical role in the occurrence and development of COPD by regulating mitophagy.

Lung emphysema and impaired macrophage elastase clearance in mucolipin 3 deficient mice

Lung emphysema and chronic bronchitis are the two most common causes of chronic obstructive pulmonary disease. Excess macrophage elastase MMP-12, which is predominantly secreted from alveolar macrophages, is known to mediate the development of lung injury and emphysema. Here, we discovered the endolysosomal cation channel mucolipin 3 (TRPML3) as a regulator of MMP-12 reuptake from broncho-alveolar fluid, driving in two independently generated Trpml3-/- mouse models enlarged lung injury, which is further exacerbated after elastase or tobacco smoke treatment. Mechanistically, using a Trpml3IRES-Cre/eR26-τGFP reporter mouse model, transcriptomics, and endolysosomal patch-clamp experiments, we show that in the lung TRPML3 is almost exclusively expressed in alveolar macrophages, where its loss leads to defects in early endosomal trafficking and endocytosis of MMP-12. Our findings suggest that TRPML3 represents a key regulator of MMP-12 clearance by alveolar macrophages and may serve as therapeutic target for emphysema and chronic obstructive pulmonary disease.

The Link between Circadian Clock Genes and Autophagy in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), a progressive respiratory disease, is characterized by the alveolar epithelium injury and persistent airway inflammation. It is documented that oscillation and dysregulated expression of circadian clock genes, like Bmal1, Per1, and Per2, involved in COPD pathogenies, including chronic inflammation and imbalanced autophagy level, and targeting the associations of circadian rhythm and autophagy is promising strategies in the management and treatment of COPD. Herein, we reviewed the mechanisms of the circadian clock and the unbalance of the autophagic level in COPD, as well as the link between the two, so as to provide further theoretical bases for the study on the pathogenesis of COPD.

MAPK15-ULK1 signaling regulates mitophagy of airway epithelial cell in chronic obstructive pulmonary disease

Airway epithelial mitochondrial oxidative stress and damage is an important pathology in chronic obstructive pulmonary disease (COPD). Mitophagy involves MAPK15-ULK1 signaling, the role of which is unknown in COPD. This study investigated MAPK15-ULK1 signaling in airway epithelial cells of COPD patients and its activation by cigarette smoke extract (CSE) in isolated human airway epithelial cells. Significant increased phosphorylation of MAPK15 and ULK1 (Ser555) was detected in the airway epithelium of COPD patients. This pathology was maintained in isolated primary COPD-epithelial cells. Compared to control cells, the protein expression of Beclin1 and the ratio of LC3II to LC3I were both significantly increased in COPD-epithelial cells. In human airway epithelial cells, CSE significantly increased the phosphorylation of MAPK15, ULK1 (Ser555), the expression of Beclin1, and the LC3II/LC3I ratio in a concentration- and time-dependent manner. Transfection with MAPK15 siRNA significantly inhibited the CSE-induced ULK1 (Ser555) phosphorylation in airway epithelial cells. Silencing of MAPK15 or ULK1 significantly reduced CSE-induced mitophagy and mitochondrial oxidative stress, thereby improving cell viability. In summary, cigarette smoke activated MAPK15-ULK1 signaling, thereby promoting mitophagy and mitochondrial oxidative stress in airway epithelial cells. This signaling pathway is activated in COPD-epithelial cells and therefore might present a novel therapeutic target for COPD.

SPATA33 is an autophagy mediator for cargo selectivity in germline mitophagy

Selective autophagic degradation of mitochondria (mitophagy) is important in maintaining proper cellular homeostasis. Here, we found that SPATA33 is a novel autophagy mediator for mitophagy in testis. The SPATA33 protein localizes on mitochondria via its binding of the carboxyl terminal with the outer mitochondrial membrane protein VDAC2. Upon starvation induction, SPATA33 is recruited to autophagosome by binding the autophagy machinery ATG16L1 via its N-terminal along with mitochondria. Notably, Spata33 knockout inhibited autophagy and overexpression can promote autophagosome formation for mitochondrial sequestration. Therefore, SPATA33 confers selectivity for mitochondrial degradation and promotes mitophagy in male germline cells.

Neuroprotective Role of GLP-1 Analog for Retinal Ganglion Cells via PINK1/Parkin-Mediated Mitophagy in Diabetic Retinopathy

GLP-1 analogs have been widely used to treat patients with type 2 diabetes in recent years and studies have found that GLP-1 analogs have multiple organ benefits. However, the role of GLP-1 analogs in diabetic retinopathy (DR), a common complication of diabetes mellitus (DM), remains controversial. Retinal ganglion cells (RGCs) are the only afferent neurons responsible for transmitting visual information to the visual center and are vulnerable in the early stage of DR. Protection of RGC is vital for visual function. The incretin glucagon-like peptide-1 (GLP-1), which is secreted by L-cells after food ingestion, could lower blood glucose level through stimulating the release of insulin. In the present study, we evaluated the effects of GLP-1 analog on RGCs both in vitro and in vivo. We established diabetic rat models in vivo and applied an RGC-5 cell line in vitro. The results showed that in high glucose conditions, GLP-1 analog alleviated the damage of RGCs. In addition, GLP-1 analog prevented mitophagy through the PINK1/Parkin pathway. Here we demonstrated the neuroprotective effect of GLP-1 analog, which may be beneficial for retinal function, and we further elucidated a novel mechanism in GLP-1 analog-regulated protection of the retina. These findings may expand the multi-organ benefits of GLP-1 analogs and provide new insights for the prevention of DR.

Autophagy Augmentation to Alleviate Immune Response Dysfunction, and Resolve Respiratory and COVID-19 Exacerbations

The preservation of cellular homeostasis requires the synthesis of new proteins (proteostasis) and organelles, and the effective removal of misfolded or impaired proteins and cellular debris. This cellular homeostasis involves two key proteostasis mechanisms, the ubiquitin proteasome system and the autophagy–lysosome pathway. These catabolic pathways have been known to be involved in respiratory exacerbations and the pathogenesis of various lung diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), idiopathic pulmonary fibrosis (IPF), acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and coronavirus disease-2019 (COVID-19). Briefly, proteostasis and autophagy processes are known to decline over time with age, cigarette or biomass smoke exposure, and/or influenced by underlying genetic factors, resulting in the accumulation of misfolded proteins and cellular debris, elevating apoptosis and cellular senescence, and initiating the pathogenesis of acute or chronic lung disease. Moreover, autophagic dysfunction results in an impaired microbial clearance, post-bacterial and/or viral infection(s) which contribute to the initiation of acute and recurrent respiratory exacerbations as well as the progression of chronic obstructive and restrictive lung diseases. In addition, the autophagic dysfunction-mediated cystic fibrosis transmembrane conductance regulator (CFTR) immune response impairment further exacerbates the lung disease. Recent studies demonstrate the therapeutic potential of novel autophagy augmentation strategies, in alleviating the pathogenesis of chronic obstructive or restrictive lung diseases and exacerbations such as those commonly seen in COPD, CF, ALI/ARDS and COVID-19.

Lactoferrin Contributes a Renoprotective Effect in Acute Kidney Injury and Early Renal Fibrosis

Patients with acute kidney injury (AKI) who survive the acute stage are at notable risk for chronic kidney disease (CKD) progression. There is no single therapy that can effectively prevent the AKI to CKD transition. Autophagy is a cytoplasmic component degradation pathway and has complex functions in several diseases, such as renal fibrosis. Previous research has shown that lactoferrin has important functions in antioxidant defense and other defense systems, protecting kidneys against various injuries. The present study investigated the effect of lactoferrin in protecting against the AKI to CKD transition. We identified 62 consensus genes with two-fold changes in clinical kidney tissues from AKI and CKD patients. Among the 62 overlay genes, the mRNA levels of LTF were significantly upregulated in the kidney tissues of AKI and CKD patients. Lactoferrin induced autophagy via the activation of the AMPK and inhibition of Akt/mTOR pathway in human kidney proximal tubular cells. Lactoferrin suppressed oxidative stress-induced cell death and apoptosis by augmenting autophagy. Lactoferrin has an antifibrotic role in human kidney tubular cells. In a mouse model of folic acid-induced AKI to CKD transition, treatment with lactoferrin recovered renal function and further suppressed renal fibrosis through the inhibition of apoptosis and the induction of autophagy. These findings identify lactoferrin as a potential therapeutic target for the prevention of the AKI to CKD transition.

Matrine: A Promising Natural Product With Various Pharmacological Activities

Matrine is an alkaloid isolated from the traditional Chinese medicine Sophora flavescens Aiton. At present, a large number of studies have proved that matrine has an anticancer effect can inhibit cancer cell proliferation, arrest cell cycle, induce apoptosis, and inhibit cancer cell metastasis. It also has the effect of reversing anticancer drug resistance and reducing the toxicity of anticancer drugs. In addition, studies have reported that matrine has a therapeutic effect on Alzheimer's syndrome, encephalomyelitis, asthma, myocardial ischemia, rheumatoid arthritis, osteoporosis, and the like, and its mechanism is mainly related to the inhibition of inflammatory response and apoptosis. Its treatable disease spectrum spans multiple systems such as the nervous system, circulatory system, and immune system. The antidisease effect and mechanism of matrine are diverse, so it has high research value. This review summarizes recent studies on the pharmacological mechanism of matrine, with a view to providing reference for subsequent research.

Nix Plays a Neuroprotective Role in Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats

Nix is located in the outer membrane of mitochondria, mediates mitochondrial fission and implicated in many neurological diseases. However, the association between Nix and subarachnoid hemorrhage (SAH) has not previously been reported. Therefore, the present study was designed to evaluate the expression of Nix and its role in early brain injury (EBI) after SAH. Adult male Sprague-Dawley (SD) rats were randomly assigned to various time points for investigation after SAH. A rat model of SAH was induced by injecting 0.3 ml of autologous non-heparinized arterial blood into the prechiasmatic cistern. The expression of Nix was investigated by Western blot and immunohistochemistry. Next, Nix-specific overexpression plasmids and small interfering RNAs (siRNAs) were separately administered. Western blot, neurological scoring, Morris water maze, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining and fluoro-jade B (FJB) staining were performed to evaluate the role of Nix in EBI following SAH. We found that Nix was expressed in neurons and its expression level in the SAH groups was higher than that in the Sham group, which peaked at 24 h after SAH. Overexpression of Nix following SAH significantly decreased the expression of translocase of outer mitochondrial membrane 20 (TOMM20, a marker of mitochondria), ameliorated neurological/cognitive deficits induced by SAH, and reduced the total number of apoptotic/neurodegenerative cells, whereas siRNA knockdown of Nix yielded opposite effects. Taken together, our findings demonstrated that the expression of Nix is increased in neurons after experimental SAH in rats, and may play a neuroprotective role in EBI following SAH.