Reactive Oxygen Species/Hypoxia-Inducible Factor-1α/Platelet-Derived Growth Factor-BB Autocrine Loop Contributes to Cocaine-Mediated Alveolar Epithelial Barrier Damage

mRNA Levels of Epithelial and Mesenchymal Markers in Lung Epithelial Cell Lines

Background

Epithelial-mesenchymal transition (EMT) is an important physiologic process that determines the outcome of lung tissue healing after injury. Stimuli and molecular cascades inducing EMT lead to up-regulation of the mesenchymal-specific genes in the alveolar epithelial cells and to down-regulation of the genes coding for epithelial markers. Alveolar epithelial cell lines are commonly used as in vitro models to study processes occurring in the lung tissue. The aim of this study is to quantify and compare mRNA expression levels of epithelial and mesenchymal markers in a number of lung epithelial cell lines.

Methods

Lung epithelial cell lines L2, R3/1 and RLE-6TN were cultured. Repeated mRNA isolation, reverse transcription, and quantitative PCR with primers to epithelial (E-cadherin, occludin, and ZO-2) and mesenchymal (α-SMA, collagen III, and vimentin) markers were performed.

Results

First, our study revealed a higher level of epithelial transcripts in the RLE-6TN cell line compared to L2 and R3/1 cells. Secondly, we have found simultaneous mRNA expression of both epithelial (E-cadherin, occludin and ZO-2) and mesenchymal (α-SMA, collagen III and vimentin) markers in all cell lines studied.

Conclusions

Our data indicate that at the transcriptional level the L2, R3/1, and RLE-6TN cell lines are at one of the intermediate stages of EMT, which opens new possibilities for the study of EMT on cell lines. Determination of the direction of changes in epithelial and mesenchymal markers will make it possible to establish the factors responsible for both EMT and reverse mesenchymal-epithelial transition.

Contributing factors common to COVID‑19 and gastrointestinal cancer

The devastating complications of coronavirus disease 2019 (COVID-19) result from the dysfunctional immune response of an individual following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events, ultimately leading to COVID-19. The authors have previously identified a number of contributing factors (CFs) common to myriad chronic diseases. Based on these observations, it was hypothesized that there may be a significant overlap between CFs associated with COVID-19 and gastrointestinal cancer (GIC). Thus, in the present study, a streamlined dot-product approach was used initially to identify potential CFs that affect COVID-19 and GIC directly (i.e., the simultaneous occurrence of CFs and disease in the same article). The nascent character of the COVID-19 core literature (~1-year-old) did not allow sufficient time for the direct effects of numerous CFs on COVID-19 to emerge from laboratory experiments and epidemiological studies. Therefore, a literature-related discovery approach was used to augment the COVID-19 core literature-based ‘direct impact’ CFs with discovery-based ‘indirect impact’ CFs [CFs were identified in the non-COVID-19 biomedical literature that had the same biomarker impact pattern (e.g., hyperinflammation, hypercoagulation, hypoxia, etc.) as was shown in the COVID-19 literature]. Approximately 2,250 candidate direct impact CFs in common between GIC and COVID-19 were identified, albeit some being variants of the same concept. As commonality proof of concept, 75 potential CFs that appeared promising were selected, and 63 overlapping COVID-19/GIC potential/candidate CFs were validated with biological plausibility. In total, 42 of the 63 were overlapping direct impact COVID-19/GIC CFs, and the remaining 21 were candidate GIC CFs that overlapped with indirect impact COVID-19 CFs. On the whole, the present study demonstrates that COVID-19 and GIC share a number of common risk/CFs, including behaviors and toxic exposures, that impair immune function. A key component of immune system health is the removal of those factors that contribute to immune system dysfunction in the first place. This requires a paradigm shift from traditional Western medicine, which often focuses on treatment, rather than prevention.

Shp2 regulates PM2.5-induced airway epithelial barrier dysfunction by modulating ERK1/2 signaling pathway

The impact of fine particulate matter (PM2.5) on public health has received increasing attention. Through various biochemical mechanisms, PM2.5 alters the normal structure and function of the airway epithelium, causing epithelial barrier dysfunction. Src homology domain 2-containing protein tyrosine phosphatase 2 (Shp2) has been implicated in various respiratory diseases; however, its role in PM2.5-induced epithelial barrier dysfunction remains unclear. Herein, we assessed the regulatory effects of Shp2 on PM2.5-mediated epithelial barrier function and tight junction (TJ) protein expression in both mice and human pulmonary epithelial (16HBE) cells. We observed that Shp2 levels were upregulated and claudin-4 levels were downregulated after PM2.5 stimulation in vivo and in vitro. Mice were exposed to PM2.5 to induce acute lung injury, and disrupted epithelial barrier function, with decreased transepithelial electrical resistance (TER) and increased paracellular flux that was observed in 16HBE cells. In contrast, the selective inhibition or knockdown of Shp2 retained airway epithelial barrier function and reversed claudin-4 downregulation that triggered by PM2.5, and these effects may occur through the ERK1/2 MAPK signaling pathway. These data highlight an important role of Shp2 in PM2.5-induced airway epithelial barrier dysfunction and suggest a possible new course of therapy for PM2.5-induced respiratory diseases.

Research Progress on Oxidative Stress and Its Nutritional Regulation Strategies in Pigs

Oxidative stress refers to the dramatic increase in the production of free radicals in human and animal bodies or the decrease in the ability to scavenging free radicals, thus breaking the antioxidation-oxidation balance. Various factors can induce oxidative stress in pig production. Oxidative stress has an important effect on pig performance and healthy growth, and has become one of the important factors restricting pig production. Based on the overview of the generation of oxidative stress, its effects on pigs, and signal transduction pathways, this paper discussed the nutritional measures to alleviate oxidative stress in pigs, in order to provide ideas for the nutritional research of anti-oxidative stress in pigs.

SIRT6 promotes angiogenesis and hemorrhage of carotid plaque via regulating HIF-1α and reactive oxygen species

As a member of Sirtuins family, SIRT6 participates in the physiological and pathological progress of DNA repair, anti-aging, metabolism, and so on. Several studies have demonstrated that knockdown of SIRT6 inhibited the development of atherosclerosis (AS), indicated SIRT6 as a protective factor for AS. However, we confirmed SIRT6 was significantly overexpressed in human unstable carotid plaques compared with stable carotid plaques. This result indicated a more complex role of SIRT6 in AS. Furthermore, we constructed mice model with unstable carotid plaque and injected them with SIRT6 overexpressed adeno-associated virus (AAV-SIRT6). AAV-SIRT6 significantly promoted angiogenesis as well as hemorrhage in plaques. In vitro, we demonstrated overexpression of SIRT6 prevented HIF-1α from degradation by deubiquitination at K37 and K532 of HIF-1α, thus promoted the expression of HIF-1α under both normoxia and hypoxia in human umbilical vein endothelial cells (HUVECs). Through regulating HIF-1α, overexpression of SIRT6 promoted invasion, migration, proliferation, as well as tube formation ability of HUVECs. Interestingly, under different conditions, SIRT6 played different roles in the function of HUVECs. Under oxidative stress, another important pathological environment for AS, SIRT6 bound to the promoter of Catalase, a main reactive oxygen species scavenger, and depleted H3K56 acetylation, thus inhibited expression and activity of Catalase at the transcriptional level. Subsequently, inhibited Catalase promoted reactive oxygen species (ROS) under oxidative stress. Accumulated ROS further aggravated oxidative stress injury of HUVECs. On one hand, SIRT6 promoted angiogenesis in plaque via HIF-1α under hypoxia. On the other hand, SIRT6 promoted injury of neovascular via ROS under oxidative stress. It is this process of continuous growth and damage that leads to hemorrhage in carotid plaque. In conclusion, we innovatively confirmed SIRT6 promoted the angiogenesis and IPH via promoting HIF-1α and ROS in different environments, thus disclosed the unknowing danger of SIRT6.

NLRP3 Inflammasome Blockade Reduces Cocaine-Induced Microglial Activation and Neuroinflammation

Cocaine use disorder is a major health crisis that is associated with increased oxidative stress and neuroinflammation. While the role of NLRP3 inflammasome in mediating neuroinflammation is well-recognized, whether cocaine induces this response remains unexplored. Based on the premise that cocaine induces both reactive oxygen species (ROS) as well as microglial activation, we hypothesized that cocaine-mediated microglial activation involves both ROS and NLRP3 signaling pathways. We examined activation of the NLRP3 pathway in microglia exposed to cocaine, followed by validation in mice administered either cocaine or saline for 7 days, with or without pretreatment with the NLRP3 inhibitor, MCC950, and in postmortem cortical brain tissues of chronic cocaine-dependent humans. We found that microglia exposed to cocaine exhibited significant induction of NLRP3 and mature IL-1β expression. Intriguingly, blockade of ROS (Tempol) attenuated cocaine-mediated priming of NLRP3 and microglial activation (CD11b). Blockade of NLRP3 by both pharmacological (MCC950) as well as gene silencing (siNLRP3) approaches underpinned the critical role of NLRP3 in cocaine-mediated activation of inflammasome and microglial activation. Pretreatment of mice with MCC950 followed by cocaine administration for 7 days mitigated cocaine-mediated upregulation of mature IL-1β and CD11b, in both the striatum and the cortical regions. Furthermore, cortical brain tissues of chronic cocaine-dependent humans also exhibited upregulated expression of the NLRP3 pathway mediators compared with non-cocaine dependent controls. Collectively, these findings suggest that cocaine activates microglia involving the NLRP3 inflammasome pathway, thereby contributing to neuroinflammation. NLRP3 can thus be considered as a potential therapeutic target for alleviating cocaine-mediated neuroinflammation.

Use of 2-dimensional cell monolayers and 3-dimensional microvascular networks on microfluidic devices shows that iron increases transendothelial adiponectin flux via inducing ROS production

BACKGROUND

Iron excess is a risk factor for cardiovascular diseases and it is important to understand the effect of iron on vascular permeability, particularly for the transport of large metabolic hormones such as adiponectin.

METHODS

We used 2-dimensional monolayers of cultured human dermal microvascular endothelial cells (HDMEC) and human umbilical vein endothelial cells (HUVEC) as well as 3-dimensional microvascular networks to measure transendothelial flux.

RESULTS

Iron supplementation reduced transendothelial electric resistance (TEER). Flux analysis indicated that under control conditions permeability of 70 kDa dextran and oligomeric forms of adiponectin were restricted in comparison with a 3 kDa dextran, however upon iron treatment permeability of the larger molecules was increased. The increased permeability and size-dependent trans-endothelial movement in response to iron was also observed in 3-dimensional microvascular networks. Mechanistically, the alteration in barrier functionality was associated with increased oxidative stress in response to iron since alterations in TEER and permeability were rescued when reactive oxygen species production was attenuated by pre-treatment with the antioxidant N-acetyl cysteine.].

CONCLUSIONS

Iron supplementation induced ROS production resulting in increased transendothelial permeability.

GENERAL SIGNIFICANCE

Altogether, this suggests that the oxidative stress associated with iron excess could play an important role in the regulation of endothelial functionality, controlling hormone action in peripheral tissues by regulating the first rate-limiting step controlling hormone access to target tissues.

mTOR-autophagy promotes pulmonary senescence through IMP1 in chronic toxicity of methamphetamine

It is growingly concerned about methamphetamine (MA)-induced lung toxicity. IMP1 is identified as a key molecule for cell life processes, but the role of IMP1 in MA-induced senescence remains unclear. The purpose of this study was to investigate whether chronic exposure to MA can cause autophagy and senescence of the lungs, whether there are interactions between Mammalian target of rapamycin (mTOR) and IMP1 and whether IMP1 is involved in pulmonary senescence promoted by mTOR-autophagy. The rats were randomly divided into control group and MA group, following by H&E staining, immunohistochemistry staining and Western blot. The alveolar epithelial cells were proceeded by ß-galactosidase staining, cell cycle detection, transfection and co-immunoprecipitation. Long-term exposure to MA led to the thickening of alveolar septum and more compact lungs. MA promoted the conversion of LC3-I to LC3-II and inhibited the activation of mTOR to induce autophagy. Bioinformatics and co-immunoprecipitation results presented the interactions between IMP1 and mTOR. MA induced cell senescence by decreasing IMP1, up-regulating p21 and p53, arresting cell cycle and increasing SA-β-gal. Overexpression of IMP1 reduced p21 and SA-β-gal to inhibit the senescence of alveolar epithelial cells. These results demonstrated that mTOR-autophagy promotes pulmonary senescence through IMP1 in chronic toxicity of methamphetamine.

HIF-1α overexpression in mesenchymal stem cell-derived exosomes mediates cardioprotection in myocardial infarction by enhanced angiogenesis

Background

Myocardial infarction (MI) is a severe disease that often associated with dysfunction of angiogenesis. Cell-based therapies for MI using mesenchymal stem cell (MSC)-derived exosomes have been well studied due to their strong proangiogenic effect. Genetic modification is one of the most common methods to enhance exosome therapy. This study investigated the proangiogenic and cardioprotective effect of exosomes derived from hypoxia-inducible factor 1-alpha (HIF-1α)-modified MSCs.

Methods

Lentivirus containing HIF-1α overexpressing vector was packaged and used to infect MSCs. Exosomes were isolated from MSC-conditioned medium by ultracentrifugation. Human umbilical vein endothelial cells (HUVECs) were treated under hypoxia condition for 48 h co-cultured with PBS, control exosomes, or HIF-1α-overexpressed exosomes, respectively. Then the preconditioned HUVECs were subjected to tube formation assay, Transwell assay, and EdU assay to evaluate the protective effect of exosomes. Meanwhile, mRNA and secretion levels of proangiogenic factors were measured by RT-qPCR and ELISA assays. In vivo assays were conducted using the rat myocardial infarction model. PBS, control exosomes, or HIF-1α-overexpressed exosomes were injected through tail vein after MI surgery. Heart function was assessed by echocardiography at days 3, 14, and 28. At day 7, mRNA and protein expression levels of proangiogenic factors in the peri-infarction area and circulation were evaluated, respectively. At day 28, hearts were collected and subjected to H&E staining, Masson’s trichrome staining, and immunofluorescent staining.

Results

HIF-1α-overexpressed exosomes rescued the impaired angiogenic ability, migratory function, and proliferation of hypoxia-injured HUVECs. Simultaneously, HIF-1α-overexpressed exosomes preserved heart function by promoting neovessel formation and inhibiting fibrosis in the rat MI model. In addition, both in vitro and in vivo proangiogenic factors mRNA and protein expression levels were elevated after HIF-1α-overexpressed exosome application.

Conclusion

HIF-1α-overexpressed exosomes could rescue the impaired angiogenic ability, migration, and proliferation of hypoxia-pretreated HUVECs in vitro and mediate cardioprotection by upregulating proangiogenic factors and enhancing neovessel formation.

The immunologic changes during different phases of intestinal anastomotic healing

Intestinal anatomosis is a complex and multicellular process that involving three overlapped phases: exudative phase, proliferative phase, and reparative phase. Undisturbed anastomotic healings are crucial for the recovery of patients after operations but unsuccessful healings are linked with a considerable mortality. This time, we concentrate on the immunologic changes during different phases of intestinal anastomotic healing and select several major immune cells and cytokines of each phase to get a better understanding of these immunologic changes in different phases, which will be significant for more precise therapy strategies in anastomoses.

Resveratrol protects the integrity of alveolar epithelial barrier via SIRT1/PTEN/p-Akt pathway in methamphetamine-induced chronic lung injury

Objectives

SIRT1 is an antioxidative factor, but its mechanism in methamphetamine (MA)‐induced lung injury remains unclear. The purpose of this study is to determine whether MA can disrupt the integrity of alveolar epithelial barrier, whether SIRT1 is involved in MA‐induced chronic lung injury and whether Resveratrol (Res) can protect the integrity of alveolar epithelial cells by regulating ROS to activate SIRT1/PTEN/p‐Akt pathway.

Materials and methods

The rats were randomly divided into control group and MA group. Extracted lungs were detected by Western blot, HE staining and immunohistochemistry. The alveolar epithelial cells were treated with MA or/and Res, following by Western blot, LDH leakage assay and flow cytometry. MOE is used for bio‐informatics prediction.

Results

Chronic exposure to MA can cause slower growth ratio of weight, increased RVI and induced lung injury including the reduced number of alveolar sacs and the thickened alveolar walls. MA‐induced apoptosis was associated with SIRT1‐related oxidative stress. Res suppressed ROS levels, activated SIRT1, negatively regulated PTEN, phosphorylated Akt, reduced LDH leakage, increased the expression of ZO‐1 and E‐cadherin and inhibited the apoptosis of alveolar epithelial cells to attenuate MA‐induced higher permeability of alveolar epithelium.

Conclusions

MA disrupted the integrity of alveolar epithelial barrier. Res inhibited oxidative stress and reversed MA‐induced higher permeability and apoptosis of alveolar epithelium by the activation of SIRT1/PTEN/p‐Akt pathway.

Simvastatin preparations promote PDGF-BB secretion to repair LPS-induced endothelial injury through the PDGFRβ/PI3K/Akt/IQGAP1 signalling pathway

Endothelial barrier dysfunction is a critical pathophysiological process of sepsis. Impaired endothelial cell migration is one of the main reasons for endothelial dysfunction. Statins may have a protective effect on endothelial barrier function. However, the effect and mechanism of statins on lipopolysaccharide (LPS)‐induced endothelial barrier dysfunction remain unclear. Simvastatin (SV) was loaded in nanostructured lipid carriers to produce SV nanoparticles (SV‐NPs). Normal SV and SV‐NPs were used to treat human umbilical vein vascular endothelial cells (HUVECs) injured by LPS. Barrier function was evaluated by monitoring cell monolayer permeability and transendothelial electrical resistance, and cell migration ability was measured by a wound healing assay. LY294002 and imatinib were used to inhibit the activity of PI3K/Akt and platelet‐derived growth factor receptor (PDGFR) β. IQ‐GTPase‐activating protein 1 (IQGAP1) siRNA was used to knockdown endogenous IQGAP1, which was used to verify the role of the PDGFRβ/PI3K/Akt/IQGAP1 pathway in SV/SV‐NPs‐mediated barrier protection in HUVECs injured by LPS. The results show that SV/SV‐NPs promoted the migration and decreased the permeability of HUVECs treated with LPS, and the efficacy of the SV‐NPs exceeded that of SV significantly. LY294002, imatinib and IQGAP1 siRNA all suppressed the barrier protection of SV/SV‐NPs. SV/SV‐NPs promoted the secretion of platelet‐derived growth factor‐BB (PDGF‐BB) and activated the PDGFRβ/PI3K/Akt/IQGAP1 pathway. SV preparations restored endothelial barrier function by restoring endothelial cell migration, which is involved in the regulation of the PDGFRβ/PI3K/Akt/IQGAP1 pathway and PDGF‐BB secretion. As an appropriate formulation for restoring endothelial dysfunction, SV‐NPs may be more effective than SV.

Oxidative stress mediates heat-induced changes of tight junction proteins in porcine sertoli cells via inhibiting CaMKKβ-AMPK pathway

Heat stress causes reversible changes in tight junction proteins in immature Sertoli cells via inhibition of the AMPK signaling pathway; these effects are accompanied by an increase in the early apoptotic rate and decrease in the cell viability of Sertoli cells. Since heat stress is known to also cause oxidative damage, in the present study, we investigated whether the earlier mentioned effects of heat stress were brought about via the induction of oxidative stress in boar Sertoli cells. Immature Sertoli cells obtained from 3-week-old piglets were subjected to heat treatment (43 °C, 30 min), and the percentage of ROS-positive cells, the malonaldehyde (MDA) concentration, and the activity of the antioxidases, including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were measured. Next, the Sertoli cells were treated with N-acetyl-l-cysteine (NAC) (1 mmol/L, 2 h), an antioxidant agent, before they were exposed to heat stress. The effects of NAC on ROS accumulation, MDA levels, antioxidase activity, the CaMKKβ-AMPK signaling pathway and expression of tight junction proteins were assessed. The results showed that heat stress reversibly increased the percentage of ROS-positive cells and MDA levels, and decreased the activity of SOD, GSH-Px, and CAT. Pretreatment with NAC abrogated these effects of heat stress. Additionally, NAC reversed the heat stress-induced decrease in the expression of CaMKKβ and dephosphorylation of AMPK. NAC also obviously rescued the heat stress-induced downregulation of tight junction proteins (claudin-11, JAM-A, occludin, and ZO-1) both at the mRNA and protein level. In conclusion, the findings indicate that oxidative damage participates in heat stress-induced downregulation of tight junction proteins in Sertoli cells by inhibiting the CaMKKβ-AMPK axis. Further, NAC reversed the effects of heat stress on tight junction proteins; this means that it has potential as a protective agent that can prevent reproductive dysfunction in boars under conditions of heat stress.

Major Effect of Oxidative Stress on the Male, but Not Female, SP-A1 Type II Cell miRNome

Pulmonary surfactant protein A (SP-A) plays an important role in surfactant metabolism and lung innate immunity. In humans there are two proteins, SP-A1 and SP-A2, encoded by SFTPA1 and SFTPA2, respectively, which are produced by the alveolar type II cells (T2C). We sought to investigate the differential influence of SP-A1 and SP-A2 in T2C miRNome under oxidative stress (OxS). SP-A knock out (KO) and hTG male and female mice expressing SP-A1 or SP-A2 as well as gonadectomized (Gx) mice were exposed to O₃-induced oxidative stress (OxS) or filtered air (FA). Expression of miRNAs and mRNAs was measured in the T2C of experimental animals. (a) In SP-A1 males after normalizing to KO males, significant changes were observed in the miRNome in terms of sex-OxS effects, with 24 miRNAs being differentially expressed under OxS. (b) The mRNA targets of the dysregulated miRNAs included Ago2, Ddx20, Plcg2, Irs1, Elf2, Jak2, Map2k4, Bcl2, Ccnd1, and Vhl. We validated the expression levels of these transcripts, and observed that the mRNA levels of all of these targets were unaffected in SP-A1 T2C but six of these were significantly upregulated in the KO (except Bcl2 that was downregulated). (c) Gondadectomy had a major effect on the expression of miRNAs and in three of the mRNA targets (Irs1, Bcl2, and Vhl). Ccnd1 was upregulated in KO regardless of Gx. (d) The targets of the significantly changed miRNAs are involved in several pathways including MAPK signaling pathway, cell cycle, anti-apoptosis, and other. In conclusion, in response to OxS, SP-A1 and male hormones appear to have a major effect in the T2C miRNome.

Chloramphenicol Induces Autophagy and Inhibits the Hypoxia Inducible Factor-1 Alpha Pathway in Non-Small Cell Lung Cancer Cells

Chloramphenicol is an inexpensive and excellent bactericidal antibiotic. It is used to combat anaerobic infections in the Third World countries, whereas its systemic application has been abandoned in developed countries. However, in recent years, clinicians have reintroduced chloramphenicol in clinical practice. In this study, chloramphenicol was found to repress the oxygen-labile transcription factor, hypoxia inducible factor-1 alpha (HIF-1α), in hypoxic A549 and H1299 cells. Furthermore, it suppressed the mRNA levels of vascular endothelial growth factor (VEGF) and glucose transporter 1, eventually decreasing VEGF release. Chloramphenicol initiated the autophagy pathway in treated cells, as observed by the increase in formation of Atg12-Atg5 conjugates, and in beclin-1 and LC3-II levels. The chloramphenicol-mediated HIF-1α degradation was completely reverted by autophagic flux blockage. In HIF-1α-overexpressing cells, the formation of HIF-1α/SENP-1 (Sentrin/SUMO-specific protease 1) protein complex seemed to facilitate the escape of HIF-1α from degradation. Chloramphenicol inhibited HIF-1α/SENP-1 protein interaction, thereby destabilizing HIF-1α protein. The enhancement in HIF-1α degradation due to chloramphenicol was evident during the incubation of the antibiotic before hypoxia and after HIF-1α accumulation. Since HIF-1α plays multiple roles in infections, inflammation, and cancer cell stemness, our findings suggest a potential clinical value of chloramphenicol in the treatment of these conditions.

Sensors and signals: the role of reactive oxygen species in hypoxic pulmonary vasoconstriction

When lung cells experience hypoxia, the functional response, termed hypoxic pulmonary vasoconstriction, activates a multitude of pathways with the goal of optimizing gas exchange. While previously controversial, overwhelming evidence now suggests that increased reactive oxygen species - produced at complex III of the mitochondrial electron transport chain and released into the intermembrane space - is the cellular oxygen signal responsible for triggering hypoxic pulmonary vasoconstriction. The increased reactive oxygen species (ROS) activate many downstream targets that ultimately lead to increased intracellular ionized calcium concentration and contraction of pulmonary arterial smooth muscle cells. While the specific targets of ROS signals are not completely understood, it is clear that this signalling pathway is critical for development and for normal lung function in newborns and adults.

Concurrence of autophagy with apoptosis in alveolar epithelial cells contributes to chronic pulmonary toxicity induced by methamphetamine

OBJECTIVES

Methamphetamine (MA) abuse evokes pulmonary toxicity. The aim of our study is to investigate if autophagy is induced by MA and if autophagy-initiated apoptosis in alveolar epithelial cells is involved in MA-induced chronic pulmonary toxicity.

MATERIALS AND METHODS

The rats in Control group and MA group were tested by Doppler and HE staining. The alveolar epithelial cells were treated with MA, following by western blot, RT-PCR and immunofluorescence assay.

RESULTS

Chronic exposure to MA resulted in lower growth ratio of weight and in higher heart rate and peak blood flow velocity of the main pulmonary artery of rats. MA induced infiltration of inflammatory cells in lungs, more compact lung parenchyma, thickened alveolar septum and reduction in the number of alveolar sacs. In alveolar epithelial cells, the autophagy marker LC3 and per cent of cells containing LC3-positive autophagosome were significantly increased. MA dose dependently suppressed the phosphorylation of mTOR to inactivate mTOR, elicited autophagy regulatory proteins LC3 and Beclin-1, accelerated the transformation from LC3 I to LC3 II and initiated apoptosis by decreasing Bcl-2 and increasing Bax, Bax/Bcl-2 and cleaved Caspase 3. The above results suggest that sustained autophagy was induced by long-term exposure to MA and that the increased Beclin-1 autophagy initiated apoptosis in alveolar epithelial cells.

CONCLUSIONS

Concurrence of autophagy with apoptosis in alveolar epithelial cells contributes to chronic pulmonary toxicity induced by MA.