Autophagy: a core cellular process with emerging links to pulmonary disease

Autophagy in Disease Onset and Progression

Autophagy is a biological phenomenon whereby components of cells can self-degrade using autophagosomes. During this process, cells can clear dysfunctional organelles or unwanted elements. Autophagy can recycle unnecessary biomolecules into new components or sometimes, even destroy the cells themselves. This cellular process was first observed in 1962 by Keith R. Porter et al. Since then, autophagy has been studied for over 60 years, and much has been learned on the topic. Nevertheless, the process is still not fully understood. It has been proven, for example, that autophagy can be a positive force for maintaining good health by removing older or damaged cells. By contrast, autophagy is also involved in the onset and progression of various conditions caused by pathogenic infections. These diseases generally involve several important organs in the human body, including the liver, kidney, heart, and central nervous system. The regulation of the defects of autophagy defects may potentially be used to treat some diseases. This review comprehensively discusses recent research frontiers and topics of interest regarding autophagy-related diseases.

A systematic review of the research progress of traditional Chinese medicine against pulmonary fibrosis: from a pharmacological perspective

Pulmonary fibrosis is a chronic progressive interstitial lung disease caused by a variety of etiologies. The disease can eventually lead to irreversible damage to the lung tissue structure, severely affecting respiratory function and posing a serious threat to human health. Currently, glucocorticoids and immunosuppressants are the main drugs used in the clinical treatment of pulmonary fibrosis, but their efficacy is limited and they can cause serious adverse effects. Traditional Chinese medicines have important research value and potential for clinical application in anti-pulmonary fibrosis. In recent years, more and more scientific researches have been conducted on the use of traditional Chinese medicine to improve or reduce pulmonary fibrosis, and some important breakthroughs have been made. This review paper systematically summarized the research progress of pharmacological mechanism of traditional Chinese medicines and their active compounds in improving or reducing pulmonary fibrosis. We conducted a systematic search in several main scientific databases, including PubMed, Web of Science, and Google Scholar, using keywords such as idiopathic pulmonary fibrosis, pulmonary fibrosis, interstitial pneumonia, natural products, herbal medicine, and therapeutic methods. Ultimately, 252 articles were included and systematically evaluated in this analysis. The anti-fibrotic mechanisms of these traditional Chinese medicine studies can be roughly categorized into 5 main aspects, including inhibition of epithelial-mesenchymal transition, anti-inflammatory and antioxidant effects, improvement of extracellular matrix deposition, mediation of apoptosis and autophagy, and inhibition of endoplasmic reticulum stress. The purpose of this article is to provide pharmaceutical researchers with information on the progress of scientific research on improving or reducing Pulmonary fibrosis with traditional Chinese medicine, and to provide reference for further pharmacological research.

Sexual dimorphism in chronic respiratory diseases

Sex differences in susceptibility, severity, and progression are prevalent for various diseases in multiple organ systems. This phenomenon is particularly apparent in respiratory diseases. Asthma demonstrates an age-dependent pattern of sexual dimorphism. However, marked differences between males and females exist in other pervasive conditions such as chronic obstructive pulmonary disease (COPD) and lung cancer. The sex hormones estrogen and testosterone are commonly considered the primary factors causing sexual dimorphism in disease. However, how they contribute to differences in disease onset between males and females remains undefined. The sex chromosomes are an under-investigated fundamental form of sexual dimorphism. Recent studies highlight key X and Y-chromosome-linked genes that regulate vital cell processes and can contribute to disease-relevant mechanisms. This review summarises patterns of sex differences in asthma, COPD and lung cancer, highlighting physiological mechanisms causing the observed dimorphism. We also describe the role of the sex hormones and present candidate genes on the sex chromosomes as potential factors contributing to sexual dimorphism in disease.

2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside ameliorates bleomycin-induced pulmonary fibrosis via regulating pro-fibrotic signaling pathways

2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-Glucoside (THSG) is the main active ingredient extracted from Polygonum multiflorum Thunb. (PMT), which has been reported to possess extensive pharmacological properties. Nevertheless, the exact role of THSG in pulmonary fibrosis has not been demonstrated yet. The main purpose of this study was to investigate the protective effect of THSG against bleomycin (BLM)-induced lung fibrosis in a murine model, and explore the underlying mechanisms of THSG in transforming growth factor-beta 1 (TGF-β1)-induced fibrogenesis using MRC-5 human lung fibroblast cells. We found that THSG significantly attenuated lung injury by reducing fibrosis and extracellular matrix deposition. THSG treatment significantly downregulated the expression levels of TGF-β1, fibronectin, α-SMA, CTGF, and TGFBR2, however, upregulated the expression levels of antioxidants (SOD-1 and catalase) and LC3B in the lungs of BLM-treated mice. THSG treatment decreased the expression levels of fibronectin, α-SMA, and CTGF in TGF-β1-stimulated MRC-5 cells. Conversely, THSG increased the expression levels of SOD-1 and catalase. Furthermore, treatment of THSG profoundly reduced the TGF-β1-induced generation of reactive oxygen species (ROS). In addition, THSG restored TGF-β1-induced impaired autophagy, accompany by increasing the protein levels of LC3B-II and Beclin 1. Mechanism study indicated that THSG significantly reduced TGF-β1-induced increase of TGFBR2 expression and phosphorylation of Smad2/3, Akt, mTOR, and ERK1/2 in MRC-5 cells. These findings suggest that THSG may be considered as an anti-fibrotic drug for the treatment of pulmonary fibrosis.

Akt Inhibition Promotes Autophagy and Clearance of Group B Streptococcus from the Alveolar Epithelium

Group B Streptococcus (GBS) is a gram-positive bacterium that is harmless for healthy individuals but may provoke invasive disease in young infants and immunocompromised hosts. GBS invades the epithelial barriers to enter the bloodstream, and thus strategies that enhance epithelial cell responses may hamper GBS invasion. In the present study, we sought to investigate whether the inhibition of Akt, a kinase that regulates host inflammatory responses and autophagy via suppression of mTOR, can enhance the response of non-phagocytic alveolar epithelial cells against GBS. Treatment of the alveolar epithelial cell line A549 with the Akt inhibitor MK-2206 resulted in the enhanced production of reactive oxygen species and inflammatory mediators in response to GBS. Additionally, Akt inhibition via MK-2206 resulted in elevated LC3II/I ratios and increased autophagic flux in alveolar epithelial cells. Importantly, the inhibition of Akt promoted GBS clearance both in alveolar epithelial cells in vitro and in lung tissue in vivo in a murine model of GBS pneumonia. The induction of autophagy was essential for GBS clearance in MK-2206 treated cells, as knockdown of ATG5, a critical component of autophagy, abrogated the effect of Akt inhibition on GBS clearance. Our findings highlight the role of Akt kinase inhibition in promoting autophagy and GBS clearance in the alveolar epithelium. The inhibition of Akt may serve as a promising measure to strengthen epithelial barriers and prevent GBS invasion in susceptible hosts.

Asthma Susceptibility Gene ORMDL3 Promotes Autophagy in Human Bronchial Epithelium

The genome-wide association study (GWAS)-identified asthma susceptibility risk alleles on chromosome 17q21 increase the expression of ORMDL3 (ORMDL sphingolipid biosynthesis regulator 3) in lung tissue. Given the importance of epithelial integrity in asthma, we hypothesized that ORMDL3 directly impacted bronchial epithelial function. To determine whether and how ORMDL3 expression impacts the bronchial epithelium, in studies using both primary human bronchial epithelial cells and human bronchial epithelial cell line, 16HBE (16HBE14o-), we assessed the impact of ORMDL3 on autophagy. Studies included: autophagosome detection by electron microscopy, RFP-GFP-LC3B to assess autophagic activity, and Western blot analysis of autophagy-related proteins. Mechanistic assessments included immunoprecipitation assays, intracellular calcium mobilization assessments, and cell viability assays. Coexpression of ORMDL3 and autophagy-related genes was measured in primary human bronchial epithelial cells derived from 44 subjects. Overexpressing ORMDL3 demonstrated increased numbers of autophagosomes and increased levels of autophagy-related proteins LC3B, ATG3, ATG7, and ATG16L1. ORMDL3 overexpression promotes autophagy and subsequent cell death by impairing intracellular calcium mobilization through interacting with SERCA2. Strong correlation was observed between expression of ORMDL3 and autophagy-related genes in patient-derived bronchial epithelial cells. Increased ORMDL3 expression induces autophagy, possibly through interacting with SERCA2, thereby inhibiting intracellular calcium influx, and induces cell death, impairing bronchial epithelial function in asthma.

Anti-PD-L1 antibody alleviates pulmonary fibrosis by inducing autophagy via inhibition of the PI3K/Akt/mTOR pathway

Pulmonary fibrosis is a fatal lung disease for which no effective treatment is available. Previous studies have shown that the expression of programmed cell death-Ligand (PD-L1) is significantly increased in pulmonary fibrosis, and that this is related to the occurrence of this disease. However, the underlying mechanism is not clear. To clarify the efficacy and mechanism of an anti-PD-L1 monoclonal antibody (anti-PD-L1 mAb) as a treatment for pulmonary fibrosis, we conducted histopathological, molecular, and functional analyses in a mouse model of bleomycin-induced pulmonary fibrosis and a cell model of fibrosis induced by transforming growth factor-beta 1 (TGF-β1). Our results indicate that PD-L1 is highly expressed in the lung fibrosis model. The anti-PD-L1 mAb significantly alleviated bleomycin-induced lung structural disorders and collagen deposition in mice and inhibited the proliferation, migration, activation and extracellular matrix deposition of TGF-β1-induced lung fibroblasts. Interestingly, the anti-PD-L1 mAb could also alleviate the autophagy impairment observed in pulmonary fibrosis. The potential mechanism is through the downregulation of the PI3K/Akt/mTOR signaling pathway. Our study provides evidence of the crucial ability of anti-PD-L1 mAbs to activate autophagy in the context of pulmonary fibrosis, providing a new strategy for the treatment of this disease.

Involvement of autophagy in exacerbation of eosinophilic airway inflammation in a murine model of obese asthma

Obesity is a common comorbidity in patients with asthma, and obese asthma patients present the most refractory phenotype among patients with severe asthma. Similar to the observations in non-obese asthma patients, clinical studies have revealed heterogeneity in obese asthma patients, including the occurrences of T helper (Th)2-high and Th2-low phenotypes. However, the mechanisms underlying obesity-related asthma are not completely understood. Though macroautophagy/autophagy is involved in asthma and obesity, its role in obesity-associated asthma is unknown. We hypothesized that autophagy is involved in the pathogenesis of obese asthma. For our investigations, we used high-fat diet-induced Atg5 (autophagy related 5)-deficient mice and epithelial cell-specific atg5^−/− (Scgb1a1/CCSP-atg5^−/−) obesity-induced mice. House dust mite (HDM)-sensitized atg5^−/− obese mice exhibited marked eosinophilic inflammation and airway hyper-reactivity (AHR), compared to wild-type (WT) obese mice. Analyses of atg5^−/− obese mice showed increased levels of Th2 cells but not ILC2s together with elevated expression of Th2 cytokines in the lung. In response to the HDM challenge, activated epithelial autophagy was observed in lean but not obese WT mice. Epithelium-specific deletion of Atg5 induced eosinophilic inflammation in Scgb1a1/CCSP-atg5^−/− obese mice, and genetic analyses of epithelial cells from HDM-immunized atg5^−/− obesity-induced mice showed an elevated expression of thymic stromal lymphopoietin (TSLP) and IL33. Notably, HDM-sensitized atg5^−/− mice developed TSLP- and IL33-dependent eosinophilic inflammation and AHR. Our results suggest that autophagy contributes to the exacerbation of eosinophilic inflammation in obese asthma. Modulations of autophagy may be a therapeutic target in obesity-associated asthma.

Abbreviations: AHR: airway hyper-reactivity; BAL: bronchoalveolar lavage; C_dyn: dynamic compliance; BM: bone marrow; HDM: house dust mite; HFD: high-fat diet; ILC2s: type 2 innate lymphocyte cells; ROS: reactive oxygen species; R_L: lung resistance; TSLP: thymic stromal lymphopoietin; TCC: total cell count; WT: wild type.

MicroRNA-205-5p targets E2F1 to promote autophagy and inhibit pulmonary fibrosis in silicosis through impairing SKP2-mediated Beclin1 ubiquitination

Silicosis is an occupational disease characterized by extensive pulmonary fibrosis, and the underlying pathological process remains uncertain. Herein, we explored the molecular mechanism by which microRNA‐205‐5p (miR‐205‐5p) affects the autophagy of alveolar macrophages (AMs) and pulmonary fibrosis in mice with silicosis through the E2F transcription factor 1 (E2F1)/S‐phase kinase‐associated protein 2 (SKP2)/Beclin1 axis. Alveolar macrophages (MH‐S cells) were exposed to crystalline silica (CS) to develop an in vitro model, and mice were treated with CS to establish an in vivo model. Decreased Beclin1 and increased SKP2 and E2F1 were identified in mice with silicosis. We silenced or overexpressed miR‐205‐5p, E2F1, SKP2 and Beclin1 to investigate their potential roles in pulmonary fibrosis in vivo and autophagy in vitro. Recombinant adenovirus mRFP‐GFP‐LC3 was transduced into the MH‐S cells to assay autophagic flow. Knocking down Beclin1 promoted pulmonary fibrosis and suppressed the autophagy. Co‐immunoprecipitation and ubiquitination assays suggested that SKP2 induced K48‐linked ubiquitination of Beclin1. Furthermore, chromatin immunoprecipitation‐PCR revealed the site where E2F1 bound to the SKP2 promoter between 1638 bp and 1645 bp. As shown by dual‐luciferase reporter gene assay, the transfection with miR‐205‐5p mimic inhibited the luciferase activity of the wild‐type E2F1 3′untranslated region, suggesting that miR‐205‐5p targeted E2F1. Additionally, miR‐205‐5p overexpression increased autophagy and reduced the pulmonary fibrosis, while overexpression of E2F1 or SKP2 or inhibition of Beclin1 could annul this effect. The current study elucidated that miR‐205‐5p targeted E2F1, thereby inhibiting SKP2‐mediated Beclin1 ubiquitination to promote macrophage autophagy and inhibit pulmonary fibrosis in mice with silicosis.

Autophagy, Apoptosis, the Unfolded Protein Response, and Lung Function in Idiopathic Pulmonary Fibrosis

Autophagy, apoptosis, and the unfolded protein response (UPR) are fundamental biological processes essential for manifold cellular functions in health and disease. Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal pulmonary disorder associated with aging that has limited therapies, reflecting our incomplete understanding. We conducted an observational study linking molecular markers of cell stress response pathways (UPR: BiP, XBP1; apoptosis: cleaved caspase-3; autophagy: LC3β) in lung tissues from IPF patients and correlated the expression of these protein markers to each subject's lung function measures. We hypothesized that changes in lung tissue expression of apoptosis, autophagy, and UPR markers correlate with lung function deficits in IPF. The cell stress markers BiP, XBP1, LC3β puncta, and cleaved caspase-3 were found to be elevated in IPF lungs compared to non-IPF lungs, and, further, BiP and cleaved caspase-3 co-localized in IPF lungs. Considering lung function independently, we observed that increased XBP1, BiP, and cleaved caspase-3 were each associated with reduced lung function (FEV1, FVC, TLC, RV). However, increased lung tissue expression of LC3β puncta was significantly associated with increased diffusion capacity (DLCO), an indicator of alveolar-capillary membrane function. Similarly, the co-localization of UPR (XBP1, BiP) and autophagy (LC3β puncta) markers was positively correlated with increased lung function (FEV1, FVC, TLC, DLCO). However, the presence of LC3β puncta can indicate either autophagy flux inhibition or activation. While the nature of our observational cross-sectional study design does not allow conclusions regarding causal links between increased expression of these cell stress markers, lung fibrosis, and lung function decline, it does provide some insights that are hypothesis-generating and suggests that within the milieu of active UPR, changes in autophagy flux may play an important role in determining lung function. Further research is necessary to investigate the mechanisms linking UPR and autophagy in IPF and how an imbalance in these cell stress pathways can lead to progressive fibrosis and loss of lung function. We conclude by presenting five testable hypotheses that build on the research presented here. Such an understanding could eventually lead to the development of much-needed therapies for IPF.

Asthma and Autophagy

Asthma is one of the most common diseases of the respiratory system, with typical pathogenesis and pathological changes. The current research shows that autophagy is mainly involved in the pathogenesis of asthma by regulating the body’s innate and adaptive immune responses. At the same time, a large number of epidemiological studies have shown that multiple autophagy genes affect the risk of asthma at the level of genetic polymorphism. This chapter will explore the relationship between autophagy and asthma.

Isoliquiritigenin inhibits TGF-β1-induced fibrogenesis through activating autophagy via PI3K/AKT/mTOR pathway in MRC-5 cells

Isoliquiritigenin (ISL), a natural flavonoid derived from the root of liquorice, has been reported to possess anti-inflammatory and antioxidant activities. Previous studies have found that ISL plays a crucial role in anti-fibrosis of adipose tissue and renal tissue; however, its effect on pulmonary fibrogenesis has not been demonstrated. In this study, we aimed to explore the roles and the underlying mechanisms of ISL in TGF-β1-induced fibrogenesis using human lung fibroblast-derived MRC-5 cells. Cell proliferation and migration were determined by MTT and wound healing assay, respectively. The expression levels of alpha-smooth muscle actin (α-SMA), collagen type I alpha 1 (COLIA1) and fibronectin (FN), microtubule-associated protein light chain 3 (LC3) and related signaling molecules were detected by quantitative real-time PCR, western blot and immunofluorescence assay, correspondingly. EGFP-LC3 transfection was used for autophagy analysis. The results showed that ISL inhibited the TGF-β1-induced proliferation and migration, and down-regulated the expressions of α-SMA, COLIA1 and FN. ISL treatment led to up-regulation of LC3 in TGF-β1-treated MRC-5 cells, accompanied by significant decrease in the phosphorylation levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR). In addition, the inhibitory effects of ISL on TGF-β1-induced fibrogenic features in MRC-5 cells were enhanced by pretreatment with autophagy activator Rapmycin and PI3K/AKT inhibitor LY294002 and reversed by autophagy inhibitor 3-methyladenine and PI3K/AKT activator IGF-1. Taken together, our results demonstrated that ISL could attenuate the fibrogenesis of TGF-β1-treated MRC-5 cells by activating autophagy via suppressing the PI3K/AKT/mTOR pathway. Therefore, ISL holds a great potential to be developed as a novel therapeutic agent for the treatment of pulmonary fibrosis.

TWEAK/Fn14 axis in respiratory diseases

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a well known multifunctional cytokine extensively distributed in cell types and tissues. Accumulating evidence has shown that TWEAK binding to the receptor factor-inducible 14 (Fn14) participates in diverse pathologic processes including cell proliferation and death, angiogenesis, carcinogenesis and inflammation. Interestingly, alterations of intracellular signaling cascades are correlated to the development of respiratory disease. Recently, a several lines of evidence suggests that TWEAK in lung tissues are closely associated with these signaling pathways. In this review, we explore if TWEAK could provide a novel therapeutic strategy for managing respiratory disease in general and pulmonary arterial hypertension (PAH), obstructive sleep apnea syndrome (OSAS), asthma, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and non-small cell lung cancer (NSCLC), specifically.

Protein Nutritional Support: The Classical and Potential New Mechanisms in the Prevention and Therapy of Sarcopenia

Sarcopenia commonly occurs in the elderly and patients with wasting diseases. The main reason is an imbalance in protein metabolism (protein degradation exceeding protein synthesis). It causes a serious decline in muscle strength and motion ability, even leading to long-term bed rest. Recent studies indicate that nutritional support is beneficial for ameliorating sarcopenia and restoring muscle function. This review will summarize the classical mechanisms of protein nutritional support for alleviating sarcopenia, such as modulating the ubiquitin-proteasome system, oxidative response, and cell autophagy, as well as the potential new mechanisms, including altering miRNA profiles and gut microbiota. In addition, the clinical application and outcome of protein nutritional support in the elderly and patients with wasting diseases are also introduced. Protein nutritional support is expected to provide new approaches for the prevention and adjuvant therapy of sarcopenia.

Recent advances in chronic obstructive pulmonary disease pathogenesis: from disease mechanisms to precision medicine

Chronic obstructive pulmonary disease (COPD) is a devastating lung disease with a high personal and societal burden. Exposure to toxic particles and gases, including cigarette smoke, is the main risk factor for COPD. Together with smoking cessation, current treatment strategies of COPD aim to improve symptoms and prevent exacerbations, but there is no disease-modifying treatment. The biggest drawback of today's COPD treatment regimen is the 'one size fits all' pharmacological intervention, mainly based on disease severity and symptoms and not the individual's disease pathology. To halt the worrying increase in the burden of COPD, disease management needs to be advanced with a focus on personalized treatment. The main pathological feature of COPD includes a chronic and abnormal inflammatory response within the lungs, which results in airway and alveolar changes in the lung as reflected by (small) airways disease and emphysema. Here we discuss recent developments related to the abnormal inflammatory response, ECM and age-related changes, structural changes in the small airways and the role of sex-related differences, which are all relevant to explain the individual differences in the disease pathology of COPD and improve disease endotyping. Furthermore, we will discuss the most recent developments of new treatment strategies using biologicals to target specific pathological features or disease endotypes of COPD. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Chronic Obstructive Pulmonary Disease and Autophagy

Chronic Obstructive Pulmonary Disease (COPD) is a classical chronic respiratory disease with the pathological changes involving the bronchi and alveoli. Many of the risk factors of COPD can induce autophagy in different kinds of cells in lung tissue including alveolar epithelial cells, broncho epithelial cells, and fibroblasts. Over-activation of autophagy may cause emphysema by inducing autophagic cell death. However, the bronchitis and fibrosis may be mainly caused by autophagic flux blocking. Thus, understanding the role of autophagy in the pathogenesis of COPD is important for the anti-COPD drug development.

Autophagy and its role in pulmonary hypertension

Pulmonary hypertension (PH) is a very common kind of pulmonary vascular disease, which can cause a heavier burden on patient's quality of life, even lead to death. Yet, the mechanism of PH is incomprehensive and not so clear nowadays. In recent years, more and more studies show that autophagy plays a pivotal role in the development of PH. Some modalities target on the formation or maturation of autophagosome that has emerged from our increasing knowledge of autophagy machinery, which may prevent or eliminate the process of PH. The deciphering of molecular selectivity of autophagy has also been a source of novel modulators that act specifically on selective forms of autophagy. Tremendous recent progress has opened a new possibility for modulating autophagy in complex diseases. Thus, autophagy may become a prospective choice for treatment of PH. Herein, we reviewed the literatures and discussed the role of autophagy in the development and treatment of PH.

Nur77 promotes cigarette smoke‑induced autophagic cell death by increasing the dissociation of Bcl2 from Beclin-1

Chronic obstructive pulmonary disease (COPD) is characterized by partially reversible airflow limitation and persistent alveolar destruction, and autophagy is involved in the pathogenesis of cigarette smoke (CS)‑induced COPD. Nuclear receptor 77 (Nur77) participates in a number of biological processes, including apoptosis, autophagy and in disease pathogenesis; however, the role of Nur77 in COPD remains unknown. Thus, in this study, we aimed to elucidate the role of Nur77 in COPD. We report that CS promotes Nur77 expression and nuclear export in vivo and in vitro, which increases cigarette smoke extract (CSE)‑induced autophagy. In addition, we found that lung tissues, human bronchial epithelial (HBE) cells and A549 cells exposed to CS or CSE expressed lower levels of LC3 and Beclin‑1 and contained fewer autophagosomes following Nur77 knockdown with siRNA‑Nur77. Moreover, a co‑immunoprecipitation assay demonstrated that CSE promoted autophagy, partly by accelerating the interaction between Nur77 and Bcl2, in turn leading to the increased dissociation of Bcl2 from Beclin‑1; by contrast, leptomycin B (LMB) suppressed the dissociation of Bcl2 from Beclin‑1. Taken together, the findings of this study demonstrate that Nur77 is involved in the CSE‑induced autophagic death of lung cells, and that this process is partially dependent on the increased interaction between Nur77 and Bcl2, and on the dissociation of Bcl2 from Beclin‑1. This study illustrates the role of Nur77 in bronchial and alveolar destruction following exposure to CS.

Rapamycin activates mammalian microautophagy

Autophagy-lysosome proteolysis is classified into macroautophagy (MA), microautophagy (mA) and chaperone-mediated autophagy (CMA). In contrast to MA and CMA, mA have been mainly studied in yeast. In 2011, mammalian mA was identified as a pathway to deliver cytosolic proteins into multivesicular bodies. However, its molecular mechanism is quite different from yeast mA. Using a cell-based method to evaluate mA and CMA, we revealed that rapamycin, an activator of yeast mA, significantly activated mammalian mA. Although rapamycin activates MA, mA was also activated by rapamycin in MA-deficient cells. These findings suggest that rapamycin is a first-identified activator of mammalian mA.

Ligustrazin increases lung cell autophagy and ameliorates paraquat-induced pulmonary fibrosis by inhibiting PI3K/Akt/mTOR and hedgehog signalling via increasing miR-193a expression

Background

Reactive oxygen species (ROS) levels largely determine pulmonary fibrosis. Antioxidants have been found to ameliorate lung fibrosis after long-term paraquat (PQ) exposure. The effects of antioxidants, however, on the signalling pathways involved in PQ-induced lung fibrosis have not yet been investigated sufficiently. Here, we examined the impacts of ligustrazin on lung fibrosis, in particular ROS-related autophagy and pro-fibrotic signalling pathways, using a murine model of PQ-induced lung fibrosis.

Methods

We explored the effects of microRNA-193 (miR-193a) on Hedgehog (Hh) and PI3K/Akt/mTOR signalling and oxidative stress in lung tissues. Levels of miR-193a, protein kinase B (Akt), phosphoinositide 3-Kinase (PI3K), ceclin1, mammalian target of rapamycin (mTOR), sonic hedgehog (SHH), myosin-like Bcl2 interacting protein (LC3), smoothened (Smo), and glioma-associated oncogene-1 (Gli-1) mRNAs were determined with quantitative real-time PCR. Protein levels of PI3K, p-mTOR, p-Akt, SHH, beclin1, gGli-1, LC3, smo, transforming growth factor-β1 (TGF-β1), mothers against DPP homologue-2 (Smad2), connective tissue growth factor (CTGF), collagen I, collagen III, α-smooth muscle actin (α-SMA) nuclear factor erythroid 2p45-related factor-2 (Nrf2), and p-Smad2 were detected by western blotting. In addition, α-SMA, malondialdehyde, ROS, superoxide dismutase (SOD), oxidised and reduced glutathione, hydroxyproline, and overall collagen levels were identified in lung tissues using immunohistochemistry.

Results

Long-term PQ exposure blocked miR-193a expression, reduced PI3K/Akt/mTOR signalling, increased oxidative stress, inhibited autophagy, increased Hh signalling, and facilitated the formation of pulmonary fibrosis. Ligustrazin blocked PI3K/Akt/mTOR and Hh signalling as well as reduced oxidative stress via increasing miR-193a expression and autophagy, all of which reduced pulmonary fibrosis. These effects of ligustrazin were accompanied by reduced TGF-β1, CTGF, and Collagen I and III expression.

Conclusions

Ligustrazin blocked PQ-induced PI3K/Akt/mTOR and Hh signalling by increasing miR-193a expression, thereby attenuating PQ-induced lung fibrosis.

Protective Features of Autophagy in Pulmonary Infection and Inflammatory Diseases

Autophagy is a highly conserved catabolic process involving autolysosomal degradation of cellular components, including protein aggregates, damaged organelles (such as mitochondria, endoplasmic reticulum, and others), as well as various pathogens. Thus, the autophagy pathway represents a major adaptive response for the maintenance of cellular and tissue homeostasis in response to numerous cellular stressors. A growing body of evidence suggests that autophagy is closely associated with diverse human diseases. Specifically, acute lung injury (ALI) and inflammatory responses caused by bacterial infection or xenobiotic inhalation (e.g., chlorine and cigarette smoke) have been reported to involve a spectrum of alterations in autophagy phenotypes. The role of autophagy in pulmonary infection and inflammatory diseases could be protective or harmful dependent on the conditions. In this review, we describe recent advances regarding the protective features of autophagy in pulmonary diseases, with a focus on ALI, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), tuberculosis, pulmonary arterial hypertension (PAH) and cystic fibrosis.

Autophagy and the unfolded protein response promote profibrotic effects of TGF-β1 in human lung fibroblasts

Idiopathic pulmonary fibrosis (IPF) is a lethal fibrotic lung disease in adults with limited treatment options. Autophagy and the unfolded protein response (UPR), fundamental processes induced by cell stress, are dysregulated in lung fibroblasts and epithelial cells from humans with IPF. Human primary cultured lung parenchymal and airway fibroblasts from non-IPF and IPF donors were stimulated with transforming growth factor-β₁ (TGF-β₁) with or without inhibitors of autophagy or UPR (IRE1 inhibitor). Using immunoblotting, we monitored temporal changes in abundance of protein markers of autophagy (LC3βII and Atg5-12), UPR (BIP, IRE1α, and cleaved XBP1), and fibrosis (collagen 1α2 and fibronectin). Using fluorescent immunohistochemistry, we profiled autophagy (LC3βII) and UPR (BIP and XBP1) markers in human non-IPF and IPF lung tissue. TGF-β₁-induced collagen 1α2 and fibronectin protein production was significantly higher in IPF lung fibroblasts compared with lung and airway fibroblasts from non-IPF donors. TGF-β₁ induced the accumulation of LC3βII in parallel with collagen 1α2 and fibronectin, but autophagy marker content was significantly lower in lung fibroblasts from IPF subjects. TGF-β₁-induced collagen and fibronectin biosynthesis was significantly reduced by inhibiting autophagy flux in fibroblasts from the lungs of non-IPF and IPF donors. Conversely, only in lung fibroblasts from IPF donors did TGF-β₁ induce UPR markers. Treatment with an IRE1 inhibitor decreased TGF-β1-induced collagen 1α2 and fibronectin biosynthesis in IPF lung fibroblasts but not those from non-IPF donors. The IRE1 arm of the UPR response is uniquely induced by TGF-β₁ in lung fibroblasts from human IPF donors and is required for excessive biosynthesis of collagen and fibronectin in these cells.

Autophagy in Pulmonary Diseases

The pathogenesis of pulmonary diseases is often complex and characterized by multiple cellular events, including inflammation, cell death, and cell proliferation. The mechanisms by which these events are regulated in pulmonary diseases remain poorly understood. Autophagy is an essential process for cellular homeostasis and stress adaptation in eukaryotic cells. This highly conserved cellular process involves the sequestration of cytoplasmic components in double-membrane autophagosomes, which are delivered to lysosomes for degradation. The critical roles of autophagy have been demonstrated in a wide range of pathophysiological conditions. Emerging studies have identified that autophagy plays important roles in the pathogenesis of various lung diseases. In addition, autophagy has been shown to selectively degrade subcellular targets, including proteins, organelles, and pathogens. Here, we highlight the recent advances in the molecular regulation and function of autophagy in lung diseases.

Role of OSGIN1 in mediating smoking-induced autophagy in the human airway epithelium

Enhanced macroautophagy/autophagy is recognized as a component of the pathogenesis of smoking-induced airway disease. Based on the knowledge that enhanced autophagy is linked to oxidative stress and the DNA damage response, both of which are linked to smoking, we used microarray analysis of the airway epithelium to identify smoking upregulated genes known to respond to oxidative stress and the DNA damage response. This analysis identified OSGIN1 (oxidative stress induced growth inhibitor 1) as significantly upregulated by smoking, in both the large and small airway epithelium, an observation confirmed by an independent small airway microarray cohort, TaqMan PCR of large and small airway samples and RNA-Seq of small airway samples. High and low OSGIN1 expressors have different autophagy gene expression patterns in vivo. Genome-wide correlation of RNAseq analysis of airway basal/progenitor cells showed a direct correlation of OSGIN1 mRNA levels to multiple classic autophagy genes. In vitro cigarette smoke extract exposure of primary airway basal/progenitor cells was accompanied by a dose-dependent upregulation of OSGIN1 and autophagy induction. Lentivirus-mediated expression of OSGIN1 in human primary basal/progenitor cells induced puncta-like staining of MAP1LC3B and upregulation of MAP1LC3B mRNA and protein and SQSTM1 mRNA expression level in a dose and time-dependent manner. OSGIN1-induction of autophagosome, amphisome and autolysosome formation was confirmed by colocalization of MAP1LC3B with SQSTM1 or CD63 (endosome marker) and LAMP1 (lysosome marker). Both OSGIN1 overexpression and knockdown enhanced the smoking-evoked autophagic response. Together, these observations support the concept that smoking-induced upregulation of OSGIN1 is one link between smoking-induced stress and enhanced-autophagy in the human airway epithelium.

Autophagy induction by celastrol augments protection against bleomycin-induced experimental pulmonary fibrosis in rats: Role of adaptor protein p62/ SQSTM1

Pulmonary fibrosis (PF) is a chronic pulmonary disease of unknown cause with high mortality. Autophagy is an important homeostatic process that decides the fate of cells under stress conditions. This study is aimed to investigate whether impaired autophagic activity leads to fibrosis and pharmacological induction of autophagy provides protection against bleomycin (BLM)-induced PF. A single dose of BLM (3 U/kg body weight) was administered intratracheally to induce fibrosis in rats. Celastrol, a triterpenoid (5 mg/kg body weight, intraperitoneally) was given in every 81 h for a period of 28 days. Western blot and Confocal microscopic analysis of rat lung tissue samples revealed that celastrol induces autophagy in BLM-induced rats. Transmission electron microscopic analysis supports the above findings. Celastrol increased the expressions of Beclin 1 and Vps 34, promoted the up-regulation of Atg5-Atg12-16 formation and enhanced the lipidation of LC3I to LC3II suggesting induction of autophagy by celastrol provide protection against lung fibrosis. Further, we revealed that celastrol activates autophagy by inhibiting PI3K/Akt mediated mTOR expression. In addition, we show evidences that lack of autophagy leads to accumulation of p62, an autophagy adaptor protein that is degraded by celastrol. This study helps to describe the importance of autophagic cell death as a possible therapeutic target against lung fibrosis, and celastrol as a potential candidate for the treatment options for PF.

Macrophage-derived MCPIP1 mediates silica-induced pulmonary fibrosis via autophagy

Background

Silicosis is characterized by accumulation of fibroblasts and excessive deposition of extracellular matrix. Monocyte chemotactic protein-1-induced protein 1 (MCPIP1) plays a critical role in fibrosis induced by SiO₂. However, the details of the downstream events of MCPIP1 activity in pulmonary fibrosis remain unclear. To elucidate the role of MCPIP1-induced autophagy in SiO₂-induced fibrosis, both the upstream molecular mechanisms and the functional effects of SiO₂ on cell apoptosis, proliferation and migration were investigated.

Results

Experiments using primary cultures of alveolar macrophages from healthy donors and silicosis patients as well as differentiated U937 macrophages demonstrated the following results: 1) SiO₂ induced macrophage autophagy in association with enhanced expression of MCPIP1; 2) autophagy promoted apoptosis and activation of macrophages exposed to SiO₂, and these events induced the development of silicosis; 3) MCPIP1 facilitated macrophage apoptosis and activation via p53 signaling-mediated autophagy; and 4) SiO₂-activated macrophages promoted the proliferation and migration of fibroblasts via the MCPIP1/p53-mediated autophagy pathway.

Conclusions

Our results elucidated a link between SiO₂-induced fibrosis and MCPIP1/p53 signaling-mediated autophagy. These findings provide novel insight into the potential targeting of MCPIP1 or autophagy in the development of potential therapeutic strategies for silicosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-016-0167-z) contains supplementary material, which is available to authorized users.

Associations between autophagy, the ubiquitin-proteasome system and endoplasmic reticulum stress in hypoxia-deoxygenation or ischemia-reperfusion

The activation of autophagy has been demonstrated to exert protective roles during hypoxia-reoxygenation (H/R)-induced brain injuries. This study aimed to investigate whether and how preconditioning with a proteasome inhibitor (MG-132), a proteasome promoter (Adriamycin, ADM), an autophagy inhibitor (3-methyladenine, 3-MA) and an autophagy promoter (Rapamycin, Rap) affected endoplasmic reticulum stress (ERS), the ubiquitin-proteasome system (UPS), autophagy, inflammation and apoptosis. Ubiquitin protein and 26S proteasome activity levels were decreased by MG-132 pretreatment but increased by ADM pretreatment at 2h, 4h and 6h following H/R treatment. MG-132 pretreatment led to the increased expression of autophagy-related genes, ER stress-associated genes and IκB but decreased the expression levels of NF-κB and caspase-3. ADM pretreatment led to the decreased expression of autophagy-related genes, ERS-associated genes and IκB but increased the expression of NF-κB and caspase-3. Pretreatment with 3-MA reduced the expression of autophagy-related genes, autophagy and UPS co-related genes, as well as apoptosis-related although the latter was increased by Rap pretreatment at 2h, 4h and 6h following H/R treatment. In vivo, pretreatment of rats with ADM, MG-132, 3-MA or Rap followed by ischemia-reperfusion (I/R) treatment resulted in similar changes. Proteasome inhibition preconditioning strengthened autophagy and ER stress but decreased apoptosis and inflammation. Autophagy promotion preconditioning exhibited similar changes. The combination of a proteasome inhibitor and an autophagy promoter might represent a new possible therapy to treat H/R or I/R injury-related diseases.

Fluorescent-based evaluation of chaperone-mediated autophagy and microautophagy activities in cultured cells

The autophagy-lysosome protein degradation is further classified into macroautophagy (MA), microautophagy (mA), and chaperone-mediated autophagy (CMA). While MA is involved in various functions and disease pathogenesis, little is known about CMA and mA because of the absence of easy methods to assess their activities. We have recently established a method to assess CMA activity using glyceraldehyde 3-phosphate dehydrogenase (GAPDH), a CMA substrate, and HaloTag (HT) system. Another group has recently identified a mammalian mA pathway, in which substrates are delivered to late endosomes in an heat shock cognate protein (Hsc)70-dependent manner. Because Hsc70 is also involved in CMA, our method would detect both CMA and mA activities. In this study, we attempted to assess CMA and mA activities separately through the siRNA-mediated knockdown of CMA- and mA-related proteins. Knockdown of LAMP2A, a CMA-related protein, and TSG101, an mA-related protein, significantly but only partially decreased the punctate accumulation of GAPDH-HT in AD293 cells and primary cultured rat cortical neurons. Compounds that activate CMA significantly increased GAPDH-HT puncta in TSG101-knockdown cells, but not in LAMP2A-knockdown cells, suggesting that punctate accumulation of GAPDH-HT under LAMP2A- and TSG101-knockdown represents mA and CMA activities, respectively. We succeeded in establishing the method to separately evaluate CMA and mA activities by fluorescence observation.

V-akt murine thymoma viral oncogene homolog 3 (AKT3) contributes to poor disease outcome in humans and mice with pneumococcal meningitis

Pneumococcal meningitis is the most common and severe form of bacterial meningitis. Fatality rates are substantial, and long-term sequelae develop in about half of survivors. Here, we have performed a prospective nationwide genetic association study using the Human Exome BeadChip and identified gene variants in encoding dynactin 4 (DCTN4), retinoic acid early transcript 1E (RAET1E), and V-akt murine thymoma viral oncogene homolog 3 (AKT3) to be associated with unfavourable outcome in patients with pneumococcal meningitis. No clinical replication cohort is available, so we validated the role of one of these targets, AKT3, in a pneumococcal meningitis mouse model. Akt3 deficient mice had worse survival and increased histopathology scores for parenchymal damage (infiltration) and vascular infiltration (large meningeal artery inflammation) but similar bacterial loads, cytokine responses, compared to wild-type mice. We found no differences in cerebrospinal fluid cytokine levels between patients with risk or non-risk alleles. Patients with the risk genotype (rs10157763, AA) presented with low scores on the Glasgow Coma Scale and high rate of epileptic seizures. Thus, our results show that AKT3 influences outcome of pneumococcal meningitis.

Cartography of Pathway Signal Perturbations Identifies Distinct Molecular Pathomechanisms in Malignant and Chronic Lung Diseases

Lung diseases are described by a wide variety of developmental mechanisms and clinical manifestations. Accurate classification and diagnosis of lung diseases are the bases for development of effective treatments. While extensive studies are conducted toward characterization of various lung diseases at molecular level, no systematic approach has been developed so far. Here we have applied a methodology for pathway-centered mining of high throughput gene expression data to describe a wide range of lung diseases in the light of shared and specific pathway activity profiles. We have applied an algorithm combining a Pathway Signal Flow (PSF) algorithm for estimation of pathway activity deregulation states in lung diseases and malignancies, and a Self Organizing Maps algorithm for classification and clustering of the pathway activity profiles. The analysis results allowed clearly distinguish between cancer and non-cancer lung diseases. Lung cancers were characterized by pathways implicated in cell proliferation, metabolism, while non-malignant lung diseases were characterized by deregulations in pathways involved in immune/inflammatory response and fibrotic tissue remodeling. In contrast to lung malignancies, chronic lung diseases had relatively heterogeneous pathway deregulation profiles. We identified three groups of interstitial lung diseases and showed that the development of characteristic pathological processes, such as fibrosis, can be initiated by deregulations in different signaling pathways. In conclusion, this paper describes the pathobiology of lung diseases from systems viewpoint using pathway centered high-dimensional data mining approach. Our results contribute largely to current understanding of pathological events in lung cancers and non-malignant lung diseases. Moreover, this paper provides new insight into molecular mechanisms of a number of interstitial lung diseases that have been studied to a lesser extent.

Structure, functional regulation and signaling properties of Rap2B

The Ras family small guanosine 5'-triphosphate (GTP)-binding protein Rap2B is is a member of the Ras oncogene family and a novel target of p53 that regulates the p53-mediated pro-survival function of cells. The Rap2B protein shares ~90% homology with Rap2A, and its sequence is 70% identical to other members of the Rap family such as RaplA and RaplB. As a result, Rap2B has been theorized to have similar signaling effectors to the GTPase-binding protein Rap, which mediates various biological functions, including the regulation of sterile 20/mitogen-activated proteins. Since its identification in the early 1990s, Rap2B has elicited a considerable interest. Numerous studies indicate that Rap2B exerts specific biological functions, including binding and stimulating phospholipase C-ε and interferon-γ. In addition, downregulation of Rap2B affects the growth of melanoma cells. The present review summarizes the possible effectors and biological functions of Rap2B. Increasing evidence clearly supports the association between Rap2B function and tumor development. Therefore, it is conceivable that anticancer drugs targeting Rap2B may be generated as novel therapies against cancer.

Lack of autophagy induces steroid-resistant airway inflammation

BACKGROUND

Neutrophilic corticosteroid-resistant asthma accounts for a significant proportion of asthma; however, little is known about the mechanisms that underlie the pathogenesis of the disease.

OBJECTIVE

We sought to address the role of autophagy in lung inflammation and the pathogenesis of corticosteroid-resistant neutrophilic asthma.

METHODS

We developed CD11c-specific autophagy-related gene 5 (Atg5)(-/-) mice and used several murine models to investigate the role of autophagy in asthmatic patients.

RESULTS

For the first time, we found that deletion of the Atg5 gene specifically in CD11c(+) cells, which leads to impairment of the autophagy pathway, causes unprovoked spontaneous airway hyperreactivity and severe neutrophilic lung inflammation in mice. We found that severe lung inflammation impairs the autophagy pathway, particularly in pulmonary CD11c(+) cells in wild-type mice. We further found that adoptive transfer of Atg5(-/-), but not wild-type, bone marrow-derived dendritic cells augments lung inflammation with increased IL-17A levels in the lungs. Our data indicate that neutrophilic asthma in Atg5(-/-) mice is glucocorticoid resistant and IL-17A dependent.

CONCLUSION

Our results suggest that lack of autophagy in pulmonary CD11c(+) cells induces neutrophilic airway inflammation and hyperreactivity.

mTOR Overactivation and Compromised Autophagy in the Pathogenesis of Pulmonary Fibrosis

The mammalian target of rapamycin (mTOR) signaling pathway in pulmonary fibrosis was investigated in cell and animal models. mTOR overactivation in alveolar epithelial cells (AECs) was achieved in the conditional and inducible Tsc1 knock-down mice SPC-rtTA/TetO-Cre/Tsc1^fx/+ (STT). Doxycycline caused Tsc1 knock-down and consequently mTOR activation in AECs for the STT mice. Mice treated with bleomycin exhibited increased mortality and pulmonary fibrosis compared with control mice. In wild-type C57BL/6J mice, pretreatment with rapamycin attenuated the bleomycin-mediated mortality and fibrosis. Rapamycin-mediated mouse survival benefit was inhibited by chloroquine, an autophagy inhibitor. Autophagosomes were decreased in the lungs after bleomycin exposure. Rapamycin induced the production of autophagosomes and diminished p62. We concluded that mTOR overactivation in AECs and compromised autophagy in the lungs are involved in the pathogenesis of pulmonary fibrosis. The suppression of mTOR and enhancement of autophagy may be used for treatment of pulmonary fibrosis.

Berberine inhibits Smad and non-Smad signaling cascades and enhances autophagy against pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fibroproliferative lung disorder of unknown aetiology. Transforming growth factor-β1 (TGF-β1)-mediated Smad and non-Smad signaling cascades are considered as central players in accelerating pulmonary fibrosis. We earlier reported berberine's amelioration against TGF-β1-mediated pro-fibrotic effects in bleomycin-induced pulmonary fibrosis. The present study aimed to determine the regulatory role of berberine on abrogated Smad 2/3 and FAK-dependent PI3K/Akt-mTOR signaling cascades in bleomycin-induced pulmonary fibrosis. Male Wistar rats were subjected to single intratracheal instillation of bleomycin (2.5 U/kg) on day 0, and berberine treatments were provided in either preventive or therapeutic modes, respectively. Berberine mitigated the elevated expression of fibrotic markers, α-smooth muscle actin (α-SMA), fibronectin, collagens I and III and reversed bleomycin-induced ultrastructural alterations in the lungs. Berberine inhibited the bleomycin-induced raise in p-Smad 2/3 and enhanced Smad 7 expression. Berberine blocked the activation of FAK and PI3K/Akt against bleomycin-induced dysregulation, with subsequent raise in PTEN expression. In addition, by inhibiting p-mTOR, berberine stimulated autophagy as evidenced by increase in Beclin-1, LC3-II levels with enhanced autophagosome formation. Cumulatively, through targeted inhibition of dysregulated Smad and FAK-dependent PI3K/Akt-mTOR signaling axis, berberine attenuated the fibrotic insults of bleomycin.

KEY MESSAGE

Berberine inhibits Smad 2/3 activation and enhances Smad 7 in bleomycin-induced rat lungs. Bleomycin-induced activation of FAK is inhibited by berberine. Berberine inhibits bleomycin-induced activation of PI3K/Akt cascade. Berberine inhibits mTOR activation to enhance autophagy and suppresses fibrotic markers.

Streptococcus pneumoniae induces autophagy through the inhibition of the PI3K-I/Akt/mTOR pathway and ROS hypergeneration in A549 cells

The present study focused on the action mechanism of S. pneumoniae (Sp) in inducing autophagy in human alveolar epithelial cells. Sp, a gram-positive extracellular bacterium, activates autophagy with considerably increased microtuble-associated protein light chain 3 (LC3) punctation in A549 cells. The accumulation of typical autophagosomes and conjugation of LC3 to phosphatidylethanolamine were observed in Sp-infected cells as an indication of autophagy. Using the pneumolysin (PLY) mutant, we successfully demonstrated that PLY is involved in initiating autophagy without affecting the expression levels of PI3K-III and Beclin1. PLY-mediated autophagy depends on the inhibition of the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway. Furthermore, Sp could also lead to the reactive oxygen species (ROS) hypergeneration in A549 cells. Taken together, Sp infection-induced autophagy is PLY-mediated through ROS hypergeneration and mTOR inhibition. PI3K-I and rapamycin (autophagy inducers) enhanced bacterial clearance, whereas wortmannin (autophagy inhibitor) and acetylcysteine (ROS inhibitor) reduced intracellular bacteria clearance. Thus, Sp-induced autophagy represents a host-protective mechanism, providing new insight into the pathogenesis of respiratory tract Sp infection.

Directly observed treatment short course for tuberculosis. What happens to them in the long term?

BACKGROUND

Though Directly Observed Treatment Short course (DOTS) is found effective in many controlled trials, few studies have examined its effectiveness under programmatic conditions. DOTS based Revised National TB Control Programme (RNTCP) was initiated in Ernakulam district of Kerala state in June 2000. It now covers all of India. It now seems appropriate to do an evaluation of RNTCP at field level.

AIM

This study aims to document impact of DOTS in providing productive life to tuberculosis patients and measure rate of clinical recurrence under program conditions.

METHODS

Retrospective cohort study using interview with structured, peer reviewed and validated questionnaire among cohort of new smear positive patients registered in RNTCP from January 2002 to December 2003 and declared cured/Treatment completed. We have contacted 1173 patients (62.2% of the cohort) for the study at their homes by devising a strategy to identify and trace patients from address given in TB registers.

RESULTS

Mean age of identified patients is 51.9 years. 82.4% were males. 79% patients report full supervision in the intensive period. After seven years 64.1% are healthy, work and earn; 29.8% report residual respiratory problems; 0.3% of symptomatic patients were diagnosed with smear positive pulmonary tuberculosis. Relapse calculated as worst case scenario for full target population (dead and migrated inclusive) is 9.27%. Age specific mortality is 4-6 times higher than in a comparable general population.

CONCLUSIONS

DOTS treatment under program conditions makes a measurable reduction in tuberculosis morbidity. Though high proportion of patients remains productive after DOTS, a significant proportion complains of residual respiratory symptoms. Age specific mortality of Post tuberculosis patients is high compared to general population. Close follow up irrespective of duration of symptoms may help to determine the causes of high residual morbidity and mortality rates.

Autophagy as a Possible Underlying Mechanism of Nanomaterial Toxicity

The rapid development of nanotechnologies is raising safety concerns because of the potential effects of engineered nanomaterials on human health, particularly at the respiratory level. Since the last decades, many in vivo studies have been interested in the pulmonary effects of different classes of nanomaterials. It has been shown that some of them can induce toxic effects, essentially depending on their physico-chemical characteristics, but other studies did not identify such effects. Inflammation and oxidative stress are currently the two main mechanisms described to explain the observed toxicity. However, the exact underlying mechanism(s) still remain(s) unknown and autophagy could represent an interesting candidate. Autophagy is a physiological process in which cytoplasmic components are digested via a lysosomal pathway. It has been shown that autophagy is involved in the pathogenesis and the progression of human diseases, and is able to modulate the oxidative stress and pro-inflammatory responses. A growing amount of literature suggests that a link between nanomaterial toxicity and autophagy impairment could exist. In this review, we will first summarize what is known about the respiratory effects of nanomaterials and we will then discuss the possible involvement of autophagy in this toxicity. This review should help understand why autophagy impairment could be taken as a promising candidate to fully understand nanomaterials toxicity.

Discovery of Emphysema Relevant Molecular Networks from an A/J Mouse Inhalation Study Using Reverse Engineering and Forward Simulation (REFS™)

Chronic obstructive pulmonary disease (COPD) is a respiratory disorder caused by extended exposure of the airways to noxious stimuli, principally cigarette smoke (CS). The mechanisms through which COPD develops are not fully understood, though it is believed that the disease process includes a genetic component, as not all smokers develop COPD. To investigate the mechanisms that lead to the development of COPD/emphysema, we measured whole genome gene expression and several COPD-relevant biological endpoints in mouse lung tissue after exposure to two CS doses for various lengths of time. A novel and powerful method, Reverse Engineering and Forward Simulation (REFS™), was employed to identify key molecular drivers by integrating the gene expression data and four measured COPD-relevant endpoints (matrix metalloproteinase (MMP) activity, MMP-9 levels, tissue inhibitor of metalloproteinase-1 levels and lung weight). An ensemble of molecular networks was generated using REFS™, and simulations showed that it could successfully recover the measured experimental data for gene expression and COPD-relevant endpoints. The ensemble of networks was then employed to simulate thousands of in silico gene knockdown experiments. Thirty-three molecular key drivers for the above four COPD-relevant endpoints were therefore identified, with the majority shown to be enriched in inflammation and COPD.

Defective autophagy impairs ATF3 activity and worsens lung injury during endotoxemia

Autophagy has emerged as a key regulator of the inflammatory response. To examine the role of autophagy in the development of organ dysfunction during endotoxemia, wild-type and autophagy-deficient (Atg4b-null) mice were challenged with lipopolysaccharide. Animals lacking Atg4b showed increased mortality after endotoxemia. Among the different organs studied, only the lungs showed significant differences between genotypes, with increased damage in mutant animals. Autophagy was activated in lungs from wild-type, LPS-treated mice. Similarly, human bronchial cells show an increased autophagy when exposed to serum from septic patients. We found an increased inflammatory response (increased neutrophilic infiltration, higher levels of Il6, Il12p40, and Cxcl2) in the lungs from knockout mice and identified perinuclear sequestration of the anti-inflammatory transcription factor ATF3 as the putative mechanism responsible for the differences between genotypes. Finally, induction of autophagy by starvation before LPS exposure resulted in a dampened pulmonary response to LPS in wild-type, but not knockout, mice. Similar results were found in human bronchial cells exposed to LPS. Our results demonstrate the central role of autophagy in the regulation of the lung response to endotoxemia and sepsis and its potential modulation by nutrition.

KEY MESSAGES

Endotoxemia and sepsis trigger autophagy in lung tissue. Defective autophagy increases mortality and lung inflammation after endotoxemia. Impairment of autophagy results is perinuclear ATF3 sequestration. Starvation ameliorates lung injury by an autophagy-dependent mechanism.

Oxidative stress-induced autophagy: role in pulmonary toxicity

Autophagy is an evolutionarily conserved catabolic process important in regulating the turnover of essential proteins and in elimination of damaged organelles and protein aggregates. Autophagy is observed in the lung in response to oxidative stress generated as a consequence of exposure to environmental toxicants. Whether autophagy plays role in promoting cell survival or cytotoxicity is unclear. In this article recent findings on oxidative stress-induced autophagy in the lung are reviewed; potential mechanisms initiating autophagy are also discussed. A better understanding of autophagy and its role in pulmonary toxicity may lead to the development of new strategies to treat lung injury associated with oxidative stress.

Impairment of autophagy decreases ventilator-induced lung injury by blockade of the NF-κB pathway

Excessive lung stretch triggers lung inflammation by activation of the NF-κB pathway. This route can be modulated by autophagy, an intracellular proteolytic system. Our objective was to study the impact of the absence of autophagy in a model of ventilator-induced lung injury. Mice lacking Autophagin-1/ATG4B (Atg4b-/-), a critical protease in the autophagic pathway, and their wild-type counterparts were studied in baseline conditions and after mechanical ventilation. Lung injury, markers of autophagy, and activation of the inflammatory response were evaluated after ventilation. Mechanical ventilation increased autophagy and induced lung injury in wild-type mice. Atg4b-/- animals showed a decreased lung injury after ventilation, with less neutrophilic infiltration than their wild-type counterparts. As expected, autophagy was absent in mutant animals, resulting in the accumulation of p62 and ubiquitinated proteins. Activation of the canonical NF-κB pathway was present in ventilated wild-type, but not Atg4b-deficient, animals. Moreover, these mutant mice showed an accumulation of ubiquitinated IκB. High-pressure ventilation partially restored the autophagic response in Atg4b-/- mice and abolished the differences between genotypes. In conclusion, impairment of autophagy results in an ameliorated inflammatory response to mechanical ventilation and decreases lung injury. The accumulation of ubiquitinated IκB may be responsible for this effect.

Self-eating: friend or foe? The emerging role of autophagy in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis is the most common and severe form of idiopathic interstitial pneumonias. Despite an exponential increase in our understanding of potentially important mediators and mechanisms, the pathogenesis remains elusive, and little therapeutic progress has been made in the last few years. Mortality in 3-5 years is still 50%. Autophagy, a highly conserved homeostatic mechanism necessary for cell survival, has been recently implicated in the pathogenesis of pulmonary disorders. In this paper we aim to highlight some key issues regarding the process of autophagy and its possible association with the pathogenesis of idiopathic pulmonary fibrosis.

Construction of a computable network model for DNA damage, autophagy, cell death, and senescence

Towards the development of a systems biology-based risk assessment approach for environmental toxicants, including tobacco products in a systems toxicology setting such as the “21st Century Toxicology”, we are building a series of computable biological network models specific to non-diseased pulmonary and cardiovascular cells/tissues which capture the molecular events that can be activated following exposure to environmental toxicants. Here we extend on previous work and report on the construction and evaluation of a mechanistic network model focused on DNA damage response and the four main cellular fates induced by stress: autophagy, apoptosis, necroptosis, and senescence. In total, the network consists of 34 sub-models containing 1052 unique nodes and 1538 unique edges which are supported by 1231 PubMed-referenced literature citations. Causal node-edge relationships are described using the Biological Expression Language (BEL), which allows for the semantic representation of life science relationships in a computable format. The Network is provided in .XGMML format and can be viewed using freely available network visualization software, such as Cytoscape.