Rapamycin protects against paraquat-induced pulmonary fibrosis: Activation of Nrf2 signaling pathway

Sustained-Release Rapamycin-Eluting Cobalt-Based Alloy Stent Ameliorates Ureteral Stricture in Mini-Pigs by Regulating TGF-β1/Smad3/mTOR/4EBP1/eIF4E Signaling Pathways

Purpose: To assess the feasibility and efficacy of sustained-release rapamycin-eluting metal stent in the repair of thermal injury-induced ureteral stricture in mini-pigs and explore its underlying mechanisms. Materials and Methods: A total of 18 female mini-pigs were used in this study. At 1 month after effective establishment of ureteral stricture model, they were randomly divided into normal control, model, bare-metal stent, and rapamycin-eluting stent groups. Before and at 4 weeks after stent placement, all animals underwent retrograde ureterography and single-photon emission computed tomography. Histologic examination was performed to assess the histomorphologic changes of the ureteral tissues. Real-time quantitative polymerase chain reaction and Western blot analysis were used to evaluate the expression levels of pro-fibrotic factors, transforming growth factor-beta1 (TGF-β1) and Smad3, as well as mammalian target of rapamycin (mTOR) downstream effectors, 4E binding protein 1 (4EBP1) and eukaryotic initiation factor 4E (eIF4E), in the ureteral stricture tissues. Results: Four weeks after stent placement, ureteral stricture was significantly ameliorated, and the glomerular filtration rate was significantly improved in the rapamycin-eluting stent group than the model and bare-metal stent groups (all p < 0.05). Pathologic examinations revealed obviously reduced fibroblasts and collagen fibers in the submucosa of the rapamycin-eluting stent group. The mRNA and protein expression levels of TGF-β1, Smad3, 4EBP1, and eIF4E were significantly decreased in the rapamycin-eluting stent group than the model and bare-metal stent groups (p < 0.05), whereas no significant difference was found between the model and bare-metal stent groups, indicating that rapamycin-eluting stent can inhibit fibroblast proliferation and attenuate fibrosis in the ureteral tissues. Conclusion: Sustained-release rapamycin-eluting stent can effectively ameliorate thermal injury-induced ureteral stricture in mini-pigs. The mechanism may be related to the role of rapamycin in inhibiting TGF-β1 and Smad3 expression, promoting the ureteral tissue remodeling through blocking mTOR, and suppressing 4EBP1 and eIF4E expression in the ureteral tissues. Sustained-release rapamycin-eluting stent deserves further investigation as a potentially effective means of treating iatrogenic ureteral strictures.

Dimethyl fumarate effects on paraquat-induced hepatotoxicity in mice via anti-oxidative, anti-inflammatory, and anti-apoptotic activities

Paraquat (PQ) toxicity is a common problem in the world, associated with oxidative stress, inflammation, and apoptosis. Therefore, the use of agents that reduce these disorders can be effective in the treatment of PQ toxicity. The protective effects of dimethyl fumarate (DMF) on liver disorders have been suggested in many reports. In this study, mice were divided into 6 groups; control, PQ (30 mg/kg, i.p., at day 4), DMF (100 mg/kg, p.o.), and PQ groups pretreated by DMF in three doses 10, 30, and 100 mg/kg, respectively. DMF was administered for 7 days to counteract PQ-induced liver toxicity. On the 8th day, mice were euthanized with ketamine/xylazine, and serum factors, oxidative stress markers, apoptosis index, and inflammatory markers were measured. PQ significantly increased the activity level of serum enzymes, thiobarbituric acid reactive substances, apoptotic factor (Bax/Bcl-2 ratio), inflammatory factors (NF-κB protein expression, tumor necrosis factor-α, interleukin-1β), nitric oxide, and Nrf-2 protein expression. Furthermore, PQ decreased hepatic total thiol and activity levels of catalase, superoxide dismutase, and glutathione peroxidase. However, DMF reduced the harmful effects caused by the imbalance in the oxidant and antioxidant system and histopathological damage in PQ-poisoned mice and improved the damage caused by inflammation and apoptosis.

Sirolimus suppresses circulating fibrocytes in idiopathic pulmonary fibrosis in a randomized controlled crossover trial

BACKGROUNDFibrocytes are BM-derived circulating cells that traffic to the injured lungs and contribute to fibrogenesis. The mTOR inhibitor, sirolimus, inhibits fibrocyte CXCR4 expression, reducing fibrocyte traffic and attenuating lung fibrosis in animal models. We sought to test the hypothesis that short-term treatment with sirolimus reduces the concentration of CXCR4+ circulating fibrocytes in patients with idiopathic pulmonary fibrosis (IPF).METHODSWe conducted a short-term randomized double-blind placebo-controlled crossover pilot trial to assess the safety and tolerability of sirolimus in IPF. Participants were randomly assigned to sirolimus or placebo for approximately 6 weeks, and after a 4-week washout, they were assigned to the alternate treatment. Toxicity, lung function, and the concentration of circulating fibrocytes were measured before and after each treatment.RESULTSIn the 28 study participants, sirolimus resulted in a statistically significant 35% decline in the concentration of total fibrocytes, 34% decline in CXCR4+ fibrocytes, and 42% decline in fibrocytes expressing α-smooth muscle actin, but no significant change in these populations occurred on placebo. Respiratory adverse events occurred more frequently during treatment with placebo than sirolimus; the incidence of adverse events and drug tolerability did not otherwise differ during therapy with drug and placebo. Lung function was unaffected by either treatment, with the exception of a small decline in gas transfer during treatment with placebo.CONCLUSIONAs compared with placebo, short-term treatment with sirolimus resulted in reduction of circulating fibrocyte concentrations in participants with IPF, with an acceptable safety profile.TRIAL REGISTRATIONClinicalTrials.gov, accession no. NCT01462006.FUNDINGNIH R01HL098329 and American Heart Association 18TPA34170486.

Dimethyl fumarate attenuates paraquat-induced pulmonary oxidative stress, inflammation and fibrosis in mice

Paraquat (PQ) is the most important cationic bipyridyl herbicide in the agricultural industry, which is very toxic to humans and animals and causes disruption in many organs, mainly in the lungs. Dimethyl fumarate (DMF) is an immune-modulating drug used in the treatment of multiple sclerosis and psoriasis shows antioxidant, anti-inflammatory, and antifibrotic effects. In this study, the ameliorative effects of DMF (10, 30 and 100 mg/kg, orally) on PQ (30 mg/kg) model of lung damage were evaluated in male mice. DMF was given daily for 7 days and PQ was administrated in the fourth day in a single dose. On the eighth day, the animals were sacrificed, and their lung tissue were removed. The results indicated that DMF can ameliorate PQ-induced the significant increase in lung index, hydroxyproline, as well as TBARS, TGF-β, NF-κB and decrease in the amount of total thiol, catalase, glutathione peroxidase, superoxide dismutase, Nrf-2, and INF-γ. The histopathological results confirmed indicated findings. The results showed that the protective effect of DMF on PQ-induced toxicity is mediated through antioxidant, anti-inflammatory and antifibrotic activities.

Discovery of a pyrano[2,3-b]pyridine derivative YX-2102 as a cannabinoid receptor 2 agonist for alleviating lung fibrosis

BACKGROUND

Pharmacological modulation of cannabinoid 2 receptor (CB2R) is a promising therapeutic strategy for pulmonary fibrosis (PF). Thus, to develop CB2R selective ligands with new chemical space has attracted much research interests. This work aims to discover a novel CB2R agonist from an in-house library, and to evaluate its therapeutic effects on PF model, as well as to disclose the pharmacological mechanism.

METHODS

Virtual screening was used to identify the candidate ligand for CB2R from a newly established in-house library. Both in vivo experiments on PF rat model and in vitro experiments on cells were performed to investigate the therapeutic effects of the lead compound and underlying mechanism.

RESULTS

A "natural product-like" pyrano[2,3-b]pyridine derivative, YX-2102 was identified that bound to CB2R with high affinity. Intraperitoneal YX-2102 injections significantly ameliorated lung injury, inflammation and fibrosis in a rat model of PF induced by bleomycin (BLM). On one hand, YX-2102 inhibited inflammatory response at least partially through modulating macrophages polarization thereby exerting protective effects. Whereas, on the other hand, YX-2102 significantly upregulated CB2R expression in alveolar epithelial cells in vivo. Its pretreatment inhibited lung alveolar epithelial-to-mesenchymal transition (EMT) in vitro and PF model induced by transforming growth factor beta-1 (TGF-β1) via a CB2 receptor-dependent pathway. Further studies suggested that the Nrf2-Smad7 pathway might be involved in.

CONCLUSION

These findings suggest that CB2R is a potential target for PF treatment and YX-2102 is a promising CB2R agonist with new chemical space.

Efficacy Analysis of Comprehensive Nursing in the Care of Ovarian Carcinoma Treated with Paclitaxel Combined with Nedaplatin

Objective

To determine the effectiveness of comprehensive nursing in the care of ovarian carcinoma (OC) patients treated with paclitaxel (PTX) plus nedaplatin (NDP).

Methods

The research population comprised 180 advanced OC patients who received treatment in the Shaanxi Cancer Hospital between November 2018 and November 2021. The enrolled cases were assigned to two groups based on different nursing plans: an observation group (OG) with 100 cases treated with comprehensive nursing and a control group (CG) with 80 cases intervened by conventional nursing. Intergroup comparisons were performed to identify statistical significance in terms of the following parameters: serum NGF, TK1, and CA15-3 levels; VAS, SAS, and SDS scores; nursing compliance; incidence of adverse reactions; and nursing satisfaction.

Results

Compared with CG, OG showed the following: (1) lower posttreatment NGF, TK1, and CA15-3 levels; (2) lower scores of SAS and SDS; (3) higher nursing compliance; and (4) lower incidence of adverse reactions and higher nursing satisfaction after nursing.

Conclusions

Comprehensive nursing far outperformed conventional nursing in the care of advanced OC patients treated with PTX plus NDP, which is worth popularizing.

The Role of Nrf2 in Pulmonary Fibrosis: Molecular Mechanisms and Treatment Approaches

Pulmonary fibrosis is a chronic, progressive, incurable interstitial lung disease with high mortality after diagnosis and remains a global public health problem. Despite advances and breakthroughs in understanding the pathogenesis of pulmonary fibrosis, there are still no effective methods for the prevention and treatment of pulmonary fibrosis. The existing treatment options are imperfect, expensive, and have considerable limitations in effectiveness and safety. Hence, there is an urgent need to find novel therapeutic targets. The nuclear factor erythroid 2-related factor 2 (Nrf2) is a central regulator of cellular antioxidative responses, inflammation, and restoration of redox balance. Accumulating reports reveal that Nrf2 activators exhibit potent antifibrosis effects and significantly attenuate pulmonary fibrosis in vivo and in vitro. This review summarizes the current Nrf2-related knowledge about the regulatory mechanism and potential therapies in the process of pulmonary fibrosis. Nrf2 orchestrates the activation of multiple protective genes that target inflammation, oxidative stress, fibroblast–myofibroblast differentiation (FMD), and epithelial–mesenchymal transition (EMT), and the mechanisms involve Nrf2 and its downstream antioxidant, Nrf2/HO−1/NQO1, Nrf2/NOX4, and Nrf2/GSH signaling pathway. We hope to indicate potential for Nrf2 system as a therapeutic target for pulmonary fibrosis.

ROS-responsive liposomes as an inhaled drug delivery nanoplatform for idiopathic pulmonary fibrosis treatment via Nrf2 signaling

Background

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic disease with pathophysiological characteristics of transforming growth factor-β (TGF-β), and reactive oxygen species (ROS)-induced excessive fibroblast-to-myofibroblast transition and extracellular matrix deposition. Macrophages are closely involved in the development of fibrosis. Nuclear factor erythroid 2 related factor 2 (Nrf2) is a key molecule regulating ROS and TGF-β expression. Therefore, Nrf2 signaling modulation might be a promising therapy for fibrosis. The inhalation-based drug delivery can reduce systemic side effects and improve therapeutic effects, and is currently receiving increasing attention, but direct inhaled drugs are easily cleared and difficult to exert their efficacy. Therefore, we aimed to design a ROS-responsive liposome for the Nrf2 agonist dimethyl fumarate (DMF) delivery in the fibrotic lung. Moreover, we explored its therapeutic effect on pulmonary fibrosis and macrophage activation.

Results

We synthesized DMF-loaded ROS-responsive DSPE-TK-PEG@DMF liposomes (DTP@DMF NPs). DTP@DMF NPs had suitable size and negative zeta potential and excellent capability to rapidly release DMF in a high-ROS environment. We found that macrophage accumulation and polarization were closely related to fibrosis development, while DTP@DMF NPs could attenuate macrophage activity and fibrosis in mice. RAW264.7 and NIH-3T3 cells coculture revealed that DTP@DMF NPs could promote Nrf2 and downstream heme oxygenase-1 (HO-1) expression and suppress TGF-β and ROS production in macrophages, thereby reducing fibroblast-to-myofibroblast transition and collagen production by NIH-3T3 cells. In vivo experiments confirmed the above findings. Compared with direct DMF instillation, DTP@DMF NPs treatment presented enhanced antifibrotic effect. DTP@DMF NPs also had a prolonged residence time in the lung as well as excellent biocompatibility.

Conclusions

DTP@DMF NPs can reduce macrophage-mediated fibroblast-to-myofibroblast transition and extracellular matrix deposition to attenuate lung fibrosis by upregulating Nrf2 signaling. This ROS-responsive liposome is clinically promising as an ideal delivery system for inhaled drug delivery.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01435-4.

Human Amnion-Derived MSCs Alleviate Acute Lung Injury and Hinder Pulmonary Fibrosis Caused by Paraquat in Rats

Methods

First, the purity of hAD-MSCs was determined by morphological observation and FCM, and the effects on the survival of paraquat-poisoned Sprague-Dawley rats were observed. All rats were randomly divided into three groups, defined as the sham control group (n = 8), model group (n = 15), and hAD-MSC-transplanted group (n = 17). Pneumonocyte damage and inflammatory cell infiltration were investigated in the three groups of rats, untreated control, paraquat only, and paraquat+hAD-MSC transplanted, using H&E staining. Fibrosis was investigated in three groups of rats using Masson's trichrome staining and Sirius red staining. The profibrotic factor TGF-β1, the composition of fibrotic collagen HYP, and the hAD-MSC-secreted immunosuppressive factor HLA-G5 in serum were investigated in the three groups of rats using ELISA. Furthermore, the distribution of hAD-MSCs was investigated in the three groups of rats using immunohistochemistry and hematoxylin staining.

Results

The hAD-MSCs exhibited typical hallmarks of MSCs, improved the state of being and survival of paraquat-poisoned rats, reduced both lung injury and inflammation, and inhibited the progression of pulmonary fibrosis by decreasing the deposition of collagen and the secretion of both TGF-β1 and HYP. The hAD-MSCs could survive in damaged lungs and secreted appropriate amounts of HLA-G5 into the serum.

Conclusion

The obtained results indicate that hAD-MSCs used to treat paraquat-induced lung injury may work through anti-inflammatory and immunosuppressive pathways and the downregulation of profibrotic elements. This study suggests that the transplantation of hAD-MSCs is a promising therapeutic approach for the treatment of paraquat-intoxicated patients.

Role of Nrf2 in Disease: Novel Molecular Mechanisms and Therapeutic Approaches - Pulmonary Disease/Asthma

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a major transcription factor involved in redox homeostasis and in the response induced by oxidative injury. Nrf2 is present in an inactive state in the cytoplasm of cells. Its activation by internal or external stimuli, such as infections or pollution, leads to the transcription of more than 500 elements through its binding to the antioxidant response element. The lungs are particularly susceptible to factors that generate oxidative stress such as infections, allergens and hyperoxia. Nrf2 has a crucial protective role against these ROS. Oxidative stress and subsequent activation of Nrf2 have been demonstrated in many human respiratory diseases affecting the airways, including asthma and chronic obstructive pulmonary disease (COPD), or the pulmonary parenchyma such as acute respiratory distress syndrome (ARDS) and pulmonary fibrosis. Several compounds, both naturally occurring and synthetic, have been identified as Nrf2 inducers and enhance the activation of Nrf2 and expression of Nrf2-dependent genes. These inducers have proven particularly effective at reducing the severity of the oxidative stress-driven lung injury in various animal models. In humans, these compounds offer promise as potential therapeutic strategies for the management of respiratory pathologies associated with oxidative stress but there is thus far little evidence of efficacy through human trials. The purpose of this review is to summarize the involvement of Nrf2 and its inducers in ARDS, COPD, asthma and lung fibrosis in both human and in experimental models.

Inhibition of Fibrotic Contraction by Sirolimus (Rapamycin) in an Ex Vivo Model of Thyroid Eye Disease

BACKGROUND

Thyroid eye disease (TED) is characterized by orbital inflammation and complicated by extraocular muscle fibrosis. Treatment with rapamycin/sirolimus has been reported to improve ocular motility and disease manifestations in TED. Whether this resulted from a primary antifibrotic effect on fibroblasts or was secondary to immune-suppression is unclear.

METHODS

In vitro contractility studies of primary orbital fibroblasts. Cells from patients with TED and controls were treated with rapamycin [mechanistic target of rapamycin an (mTOR) inhibitor] and MHY1485 (an mTOR stimulator) as well as inhibitors upstream in the same signaling cascade (saracatinib and befatinib).

RESULTS

At concentrations consistent with the therapeutic dosing range in humans, rapamycin/sirolimus significantly reduces fibrosis in orbital fibroblasts from TED patients and controls in vitro. This effect is separate from, and in addition to, its immune suppressive effect. mTOR-driven fibrotic activity is greater in TED-derived fibroblasts and can be blocked also upstream of mTOR by inhibition of src. There was no adverse effect on cell survival.

CONCLUSION

The authors present evidence for a direct antifibrotic effect of rapamycin/sirolimus in primary orbital fibroblasts. Targeting mTOR signaling presents a further and adjunctive treatment of TED alongside other immune-suppressive agents. By acting downstream of IGF1-R, sirolimus may offer a cost-effective alternative to teprotumumab therapy. Clinical case reports, now supplemented by this in vitro evidence, support the initiation of a clinical trial to treat the fibrotic sequelae of TED with this already-approved agent. Such an "off-the-shelf" therapy is a welcome prospect for TED treatment, particularly one available at a low price.

Biodegradable Stent with mTOR Inhibitor-Eluting Reduces Progression of Ureteral Stricture

In this study, we investigated the effect of mTOR inhibitor (mTORi) drug-eluting biodegradable stent (DE stent), a putative restenosis-inhibiting device for coronary artery, on thermal-injury-related ureteral stricture in rabbits. In vitro evaluation confirmed the dose-dependent effect of mTORi, i.e., rapamycin, on fibrotic markers in ureteral component cell lines. Upper ureteral fibrosis was induced by ureteral thermal injury in open surgery, which was followed by insertion of biodegradable stents, with or without rapamycin drug-eluting. Immunohistochemistry and Western blotting were performed 4 weeks after the operation to determine gross anatomy changes, collagen deposition, expression of epithelial–mesenchymal transition markers, including Smad, α-SMA, and SNAI 1. Ureteral thermal injury resulted in severe ipsilateral hydronephrosis. The levels of type III collagen, Smad, α-SMA, and SNAI 1 were increased 28 days after ureteral thermal injury. Treatment with mTORi-eluting biodegradable stents significantly attenuated thermal injury-induced urinary tract obstruction and reduced the level of fibrosis proteins, i.e., type III collagen. TGF-β and EMT signaling pathway markers, Smad and SNAI 1, were significantly modified in DE stent-treated thermal-injury-related ureteral stricture rabbits. These results suggested that intra-ureteral administration of rapamycin by DE stent provides modification of fibrosis signaling pathway, and inhibiting mTOR may result in fibrotic process change.

Oxidative Stress and Endoplasmic Reticulum Stress in Rare Respiratory Diseases

Several studies have shown that some rare respiratory diseases, such as alpha-1 antitrypsin deficiency (AATD), idiopathic pulmonary fibrosis (IPF), cystic fibrosis (CF), and primary ciliary dyskinesia (PCD) present oxidative stress (OS) and endoplasmic reticulum (ER) stress. Their involvement in these pathologies and the use of antioxidants as therapeutic agents to minimize the effects of OS are discussed in this review.

Rapamycin is Effective for Upper but not for Lower Gastrointestinal Crohn's Disease-Related Stricture: A Pilot Study

Crohn’s disease (CD)-related fibrotic stricture remains a clinical challenge because of no effective treatments. This study aimed to evaluate the potential efficacy of rapamycin in patients with CD-related strictures in different locations in gastrointestinal tract. A pilot prospective study on using rapamycin for CD-related stricture was performed from April 2015 to August 2020 in a single center in China. Fifteen patients were enrolled into the study. The clinical efficacy was evaluated by diet score and gastrointestinal obstruction symptoms score. Clinical responses were defined as the ability to tolerate the regular diet with vegetable fiber combined with a reduction of ≥75% in overall target score and a score of less than two points for each item. Three patients discontinued rapamycin for less than 1-month due to intolerance to adverse events, then, 12 patients received ≥1 dose of the rapamycin and provided ≥1 post-baseline target score after baseline were included for intent-to-treat (ITT) analysis. 100% (5/5) of patients with upper gastrointestinal strictures achieved clinical response after using rapamycin. However, no clinical response was observed in those patients with CD lesions in lower gastrointestinal tract. Adverse events occurred in 40% (6/15) of patients. No death or serious opportunistic infections were observed in the present study. This study firstly reported that rapamycin might be effective for CD-related stricture in the upper, but not in lower gastrointestinal tract.

The herbicide paraquat-induced molecular mechanisms in the development of acute lung injury and lung fibrosis

The herbicide paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridylium dichloride) is a highly toxic organic heterocyclic herbicide that has been widely used in agricultural settings. Since its commercial introduction in the early 1960s, numerous cases of fatal PQ poisonings attributed to accidental and/or intentional ingestion of PQ concentrated formulations have been reported. The clinical manifestations of the respiratory system during the acute phase of PQ poisoning mainly include acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), followed by pulmonary fibrosis in a later phase. The focus of this review is to summarize the most recent publications related to PQ-induced lung toxicity as well as the underlying molecular mechanisms for PQ-mediated pathologic processes. Growing sets of data from in vitro and in vivo models have demonstrated the involvement of the PQ in regulating lung oxidative stress, inflammatory response, epigenetics, apoptosis, autophagy, and the progression of lung fibrosis. The article also summarizes novel therapeutic avenues based on a literature review, which can be explored as potential means to combat PQ-induced lung toxicity. Finally, we also presented clinical studies on the association of PQ exposure with the incidence of lung injury and pulmonary fibrosis.

Modeling paraquat-induced lung fibrosis in C. elegans reveals KRIT1 as a key regulator of collagen gene transcription

Paraquat poisoning causes lung fibrosis, which often results in long-term pulmonary dysfunction. Lung fibrosis has been attributed to collagens accumulation, but the underlying regulatory pathway remains unclear. Here we use the genetically tractable C. elegans as a model to study collagen gene transcription in response to paraquat. We find that paraquat robustly up-regulates collagen gene transcription, which is dependent on KRI-1, a poorly studied protein homologous to human KRIT1/CCM1. KRI-1 knockdown prevents paraquat from activating the oxidative stress response transcription factor SKN-1/Nrf2, resulting in reduced collagen transcription and increased paraquat sensitivity. Using human lung fibroblasts (MRC-5), we confirm that both KRIT1 and Nrf2 are required for collagen transcription in response to paraquat. Nrf2 hyper-activation by KEAP1 knockdown bypasses KRIT1 to up-regulate collagen transcription. Our findings on the regulation of collagen gene transcription by paraquat could suggest potential strategies to treat pulmonary fibrosis caused by paraquat poisoning.

Role of epithelial-to-mesenchymal transition in the pulmonary fibrosis induced by paraquat in rats

BACKGROUND

This study aims to explore the characteristics of the epithelial-to-mesenchymal transition (EMT) process and its underlying molecular mechanisms in the period of paraquat (PQ)-induced pulmonary fibrosis (PF).

METHODS

Picrosirius red staining and collagen volume fraction were utilized to evaluate the pathological changes of PQ-induced PF in rats. Immunohistochemistry, Western blot, and real-time reverse transcriptase-polymerase chain reaction (RT-PCR) were used to measure the protein and gene expression of EMT markers, EMT-associated transcription factors, and regulators of EMT-related pathways, respectively.

RESULTS

The collagen deposition in the alveolar septum and increased PF markers were characteristics of pathological changes in PQ-induced PF, reached a peak on day 14 after PQ poisoning, and then decreased on day 21. The protein and gene expression of the fibrosis marker, EMT markers, transcription factors, and regulators of EMT-related signaling pathways significantly increased at different time points after PQ poisoning compared with corresponding controls (P<0.05), and most of them reached a peak on day 14, followed by a decrease on day 21. The gene expression of EMT markers was significantly correlated with PF markers, transcription factors, and regulators of EMT-related signaling pathways (P<0.05). The mRNA expression of transcription factors was significantly correlated with that of TGF-β1 and Smad2 (P<0.05 or P<0.01), instead of Wnt2 and β-catenin (P>0.05).

CONCLUSIONS

EMT process plays a role in the PQ-induced PF, in which most PF and EMT markers have a peak phenomenon, and its underlying molecular mechanisms might be determined by further studies.

Active mTOR in Lung Epithelium Promotes Epithelial-Mesenchymal Transition and Enhances Lung Fibrosis

The mTOR pathway is one of the key signal cascades in the pathogenesis of idiopathic pulmonary fibrosis. Previous studies have mainly focused on this pathway in the fibroblasts and/or myofibroblasts, but not in the epithelial cells. In this study, we sought to investigate the role of the mTOR pathway in lung epithelial cells in lung fibrosis. Using Sftpc-mTOR^SL1+IT transgenic mice, in which active mTOR is conditionally expressed in lung epithelial cells, we assessed the effects of chronically activated mTOR in lung epithelial cells on lung phenotypes as well as bleomycin-induced lung fibrosis. Furthermore, we isolated alveolar epithelial cell type 2 from mice and performed RNA sequencing. Sftpc-mTOR^SL1+IT transgenic mice had no obvious abnormal findings, but, after bleomycin administration, showed more severe fibrotic changes and lower lung compliance than control mice. RNA sequencing revealed Angptl4 (angiopoietin-like protein 4) as a candidate downstream gene of the mTOR pathway. In vitro studies revealed that ANGPTL4, as well as mTOR, promoted tight junction vulnerability and epithelial-mesenchymal transition. mTOR activation in lung epithelial cells promoted lung fibrosis and the expression of ANGPTL4, a novel downstream target of the mTOR pathway, which could be related to the etiology of fibrosis.

Nrf2 participates in the anti-apoptotic role of zinc in Type 2 diabetic nephropathy through Wnt/β-catenin signaling pathway

Zinc (Zn), as an essential trace element, has been approved to serve many roles in diabetic studies. Also Zn deficiency will aggravate renal damage in diabetes through suppression of nuclear factor-erythroid 2-related factor 2 (Nrf2) expression and function. The purpose of this study was to illustrate the role of Zn in renal apoptosis in diabetes and whether Nrf2 participated in the process. Type 2 diabetes mice model was induced by a single dose of streptozotocin (STZ) injection after high-fat diet (HFD) feeding for 3 months, then the mice were given diets supplemented with different concentrations of Zn (control, 30 ppm; low-concentration, 0.85 ppm). After 12-week treatment, morphology and associated protein expressions were examined. The results showed that low Zn diet significantly aggravated the level of renal apoptosis during diabetes, performed as the upregulation of caspase-3 expression. In addition, either low Zn diet or diabetes or both dramatically decreased the expression of Nrf2 and P-AKT in kidney. Moreover, the expression of β-catenin in kidney was increased markedly in diabetic groups. Mechanistic study applying human renal tubular epithelial cells (HK11) confirmed the role of Nrf2, as silencing Nrf2 expression abolished Zn supplementation protection against high sugar + high fat + low Zn-induced apoptosis and downregulation of β-catenin expression. All these results suggest that Nrf2 plays a key role in Zn protection against Type 2 diabetes induced renal apoptosis, which might be through Wnt/β-catenin signaling pathway.

Small molecule proteomics quantifies differences between normal and fibrotic pulmonary extracellular matrices

BACKGROUND

Pulmonary fibrosis is a respiratory disease caused by the proliferation of fibroblasts and accumulation of the extracellular matrix (ECM). It is known that the lung ECM is mainly composed of a three-dimensional fiber mesh filled with various high-molecular-weight proteins. However, the small-molecular-weight proteins in the lung ECM and their differences between normal and fibrotic lung ECM are largely unknown.

METHODS

Healthy adult male Sprague-Dawley rats (Rattus norvegicus) weighing about 150 to 200 g were randomly divided into three groups using random number table: A, B, and C and each group contained five rats. The rats in Group A were administered a single intragastric (i.g.) dose of 500 μL of saline as control, and those in Groups B and C were administered a single i.g. dose of paraquat (PQ) dissolved in 500 μL of saline (20 mg/kg). After 2 weeks, the lungs of rats in Group B were harvested for histological observation, preparation of de-cellularized lung scaffolds, and proteomic analysis for small-molecular-weight proteins, and similar procedures were performed on Group C and A after 4 weeks. The differentially expressed small-molecular-weight proteins (DESMPs) between different groups and the subcellular locations were analyzed.

RESULTS

Of the 1626 small-molecular-weight proteins identified, 1047 were quantifiable. There were 97 up-regulated and 45 down-regulated proteins in B vs. A, 274 up-regulated and 31 down-regulated proteins in C vs. A, and 237 up-regulated and 28 down-regulated proteins identified in C vs. B. Both the up-regulated and down-regulated proteins in the three comparisons were mainly distributed in single-organism processes and cellular processes within biological process, cell and organelle within cellular component, and binding within molecular function. Further, more up-regulated than down-regulated proteins were identified in most sub-cellular locations. The interactions of DESMPs identified in extracellular location in all comparisons showed that serum albumin (Alb) harbored the highest degree of node (25), followed by prolyl 4-hydroxylase beta polypeptide (12), integrin β1 (10), apolipoprotein A1 (9), and fibrinogen gamma chain (9).

CONCLUSIONS

Numerous PQ-induced DESMPs were identified in de-cellularized lungs of rats by high throughput proteomics analysis. The DESMPs between the control and treatment groups showed diversity in molecular functions, biological processes, and pathways. In addition, the interactions of extracellular DESMPs suggested that the extracellular proteins Alb, Itgb1, Apoa1, P4hb, and Fgg in ECM could be potentially used as biomarker candidates for pulmonary fibrosis. These results provided useful information and new insights regarding pulmonary fibrosis.

Oxidative Stress in Pulmonary Fibrosis

Oxidative stress has been linked to various disease states as well as physiological aging. The lungs are uniquely exposed to a highly oxidizing environment and have evolved several mechanisms to attenuate oxidative stress. Idiopathic pulmonary fibrosis (IPF) is a progressive age-related disorder that leads to architectural remodeling, impaired gas exchange, respiratory failure, and death. In this article, we discuss cellular sources of oxidant production, and antioxidant defenses, both enzymatic and nonenzymatic. We outline the current understanding of the pathogenesis of IPF and how oxidative stress contributes to fibrosis. Further, we link oxidative stress to the biology of aging that involves DNA damage responses, loss of proteostasis, and mitochondrial dysfunction. We discuss the recent findings on the role of reactive oxygen species (ROS) in specific fibrotic processes such as macrophage polarization and immunosenescence, alveolar epithelial cell apoptosis and senescence, myofibroblast differentiation and senescence, and alterations in the acellular extracellular matrix. Finally, we provide an overview of the current preclinical studies and clinical trials targeting oxidative stress in fibrosis and potential new strategies for future therapeutic interventions. © 2020 American Physiological Society. Compr Physiol 10:509-547, 2020.

[Hydrogen water alleviates paraquat-induced lung fibroblast injury in vitro by enhancing Nrf2 expression]

OBJECTIVE

To investigate the effects of hydrogen water on proliferation, differentiation, collagen secretion and Nrf2 expression in paraquat-induced human lung fibroblasts.

METHODS

In vitro cultured human lung fibroblasts (HFL1) exposed to 600 μmol/L paraquat (PQ) for 24 h were treated with hydrogen water with or without RNA interference of Nrf2 expression. The changes in the cell proliferation were examined using MTT assay, and the expressions of Col-I, Col-III, α-SMA and Nrf2 in the cells were detected using Western blotting, real-time quantitative PCR and immunofluorescence assay. The contents of SOD, CAT and GSH in the cells were determined with ELISA.

RESULTS

Compared with the PQ-exposed cells, the cells with hydrogen water treatment showed significantly lowered expressions of Col-I, Col-III, and α-SMA. Interference of Nrf2 expression obviously attenuated the effect of hydrogen water on PQ-exposed cells. Hydrogen water treatment significantly increased the expression of Nrf2 and promoted the production of the antioxidants in PQ-exposed lung fibroblasts.

CONCLUSIONS

Hydrogen water enhances Nrf2 expression to promote the proliferation and production of antioxidants and inhibit the differentiation and collagen secretion in PQ-exposed human lung fibroblasts in vitro.

Nrf2 and the Nrf2-Interacting Network in Respiratory Inflammation and Diseases

Atmospheric pollutants and cigarette smoke influence the human respiratory system and induce airway inflammation, injury, and pathogenesis. Activation of the NF-E2-related factor 2 (Nrf2) transcription factor and downstream antioxidant response element (ARE)-mediated transcriptions play a central role in protecting respiratory cells against reactive oxidative species (ROS) that are induced by airway toxins and inflammation. Recent studies have revealed that Nrf2 can also target and activate many genes involved in developmental programs such as cell proliferation, cell differentiation, cell death, and metabolism. Nrf2 is closely regulated by the interaction with kelch-like ECH-associated protein 1 (Keap1), while also directly interacts with a number of other proteins, including inflammatory factors, transcription factors, autophagy mediators, kinases, epigenetic modifiers, etc. It is believed that the multiple target genes and the complicated interacting network of Nrf2 account for the roles of Nrf2 in physiologies and pathogeneses. This chapter summarizes the molecular functions and protein interactions of Nrf2, as well as the roles of Nrf2 and the Nrf2-interacting network in respiratory inflammation and diseases, including acute lung injury (ALI), asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (PF), cystic fibrosis (CF), viral/bacterial infections, and lung cancers. Therapeutic applications that target Nrf2 and its interacting proteins in respiratory diseases are also reviewed.

The Protective Role of Tanshinone IIA in Silicosis Rat Model via TGF-β1/Smad Signaling Suppression, NOX4 Inhibition and Nrf2/ARE Signaling Activation

Purpose

Silicosis is an occupational disease caused by inhalation of silica and there are no effective drugs to treat this disease. Tanshinone IIA (Tan IIA), a traditional natural component, has been reported to possess anti-inflammatory, antioxidant, and anti-fibrotic properties. The current study’s purpose was to examine Tan IIA’s protective effects against silica-induced pulmonary fibrosis and to explore the underlying mechanisms.

Methods

48 male SD rats were randomly divided into four groups (n=12): i) Control group; ii) Silicosis group; iii) Tan IIA group; iv) Silicosis +Tan IIA group. Two days after modeling, the rats of Tan IIA group and Silicosis +Tan IIA group were given intraperitoneal administration 25 mg/kg/d Tan IIA for 40 days. Then, the four groups of rats were sacrificed and the lung inflammatory responses were measured by ELISA, lung damage and fibrosis were analyzed by hematoxylin and eosin (H&E) staining and Masson staining, the expression levels of collagen I, fibronectin and α-smooth muscle actin (α-SMA) were measured by immunohistochemistry. The markers of oxidative stress were measured by commercial kits, and the activity of the TGF-β1/Smad and NOX4, Nrf2/ARE signaling pathways were measured by RT-PCR and Western blotting.

Results

The silica-induced pulmonary inflammtory responses, structural damage and fibrosis were significantly attenuated by Tan IIA treatment. In addition, treatment with Tan IIA decreased collagen I, fibronectin and α-SMA expression, and inhibited TGF-β1/Smad signaling in the lung tissue. The upregulated levels of oxidative stress markers in silicosis rats were also markedly restored following Tan IIA treatment. Furthermore, treatment with Tan IIA reduced NOX4 expression and enhanced activation of the Nrf2/ARE pathway in the lung tissue of silicosis rats.

Conclusion

These findings suggest that Tan IIA may protect lung from silica damage via the suppression of TGF-β1/Smad signaling, inhibition of NOX4 expression and activation of the Nrf2/ARE pathway.

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The Regulation of NFE2L2 (NRF2) Signalling and Epithelial-to-Mesenchymal Transition in Age-Related Macular Degeneration Pathology

Age-related macular degeneration (AMD) is a mounting cause of loss of sight in the elderly in the developed countries, a trend enhanced by the continual ageing of the population. AMD is a multifactorial and only partly understood, malady. Unfortunately, there is no effective treatment for most AMD patients. It is known that oxidative stress (OS) damages the retinal pigment epithelium (RPE) and contributes to the progression of AMD. We review here the potential importance of two OS-related cellular systems in relation to AMD. First, the nuclear factor erythroid 2-related factor 2 (NFE2L2; NRF2)-mediated OS response signalling pathway is important in the prevention of oxidative damage and a failure of this system could be critical in the development of AMD. Second, epithelial-to-mesenchymal transition (EMT) represents a change in the cellular phenotype, which ultimately leads to the fibrosis encountered in RPE, a characteristic of AMD. Many of the pathways triggering EMT are promoted by OS. The possible interconnections between these two signalling routes are discussed here. From a broader perspective, the control of NFE2L2 and EMT as ways of preventing OS-derived cellular damage could be potentially valuable in the therapy of AMD.

Rapamycin attenuates the paraquat-induced pulmonary fibrosis through activating Nrf2 pathway

Oxidative stress is a key regulator of idiopathic pulmonary fibrosis. Paraquat (PQ)‐induced pulmonary fibrosis seriously endangers people's health. Rapamycin has been reported to alleviate PQ‐induced pulmonary fibrosis, but its underlying mechanism is unclear. The nuclear factor E2‐related factor 2 (Nrf2) plays an important regulatory role in the antioxidant therapy of PQ‐induced pulmonary fibrosis. In this study, we tried to confirm that rapamycin attenuates PQ‐induced pulmonary fibrosis by regulating Nrf2 pathway. In vivo, we proved that rapamycin could inhibit the degree of PQ‐induced oxidant stress as well as enhanced the expression of Nrf2. In vitro, rapamycin decreased the upregulated effects of cell death and apoptosis, fibrosis‐related factors expression and fibroblast‐to‐myofibroblast transformation by PQ treatment. In vivo, rapamycin treatment reduced fibrosis degree and the expression of fibrosis‐related factors in lung tissues of rat treated PQ. Furthermore, we also found that Nrf2 knockdown reduced the inhibitory effect of rapamycin on PQ‐induced pulmonary fibrosis, as well as decreased Nrf2 transfer from the cytoplasm into the nucleus. Our findings demonstrated that the protective effect of rapamycin is associated with the activation of the Nrf2 pathway in pulmonary fibrosis induced by PQ poisoning.

Chlorogenic acid prevents paraquat-induced apoptosis via Sirt1-mediated regulation of redox and mitochondrial function

Paraquat (PQ) is a widely used agro-chemical in agriculture and highly toxic to humans. Although the mechanism of PQ poisoning is not clear, it has been well documented that reactive oxygen species (ROS) generation and apoptosis play pivotal roles. Alternatively, chlorogenic acid (CA) is a biologically active dietary polyphenol, playing several therapeutic roles. However, it is not known whether CA has protective effect on PQ-induced apoptosis. Here, we investigated the effect of CA in preventing PQ-induced apoptosis and explored the underlying mechanisms. A549 cells were pretreated with 100 µM CA for 24 h and then exposed to 160 µM PQ for 24 h. We found that CA was effective in preventing PQ-induced apoptotic features, including the release of cytochrome c from the mitochondria to cytoplasm, the cleavages of caspase 3 and caspase 9, and the increases in levels of Bcl-2-associated X protein (Bax) and intracellular calcium ions. CA alleviated ROS production and prevented the reduction of antioxidant capacity in cells exposed to PQ by increasing NF-E2-related factor 2 (Nrf2), superoxide dismutase 2 (SOD2) and glutathione levels. In addition, CA also attenuated PQ-induced alterations of mitochondrial structure and function (such as the decreases in membrane potential and adenosine triphosphate level), and the impaired autophagic flux was improved by CA. Down-regulation of sirtuin 1 (Sirt1) by short hairpin RNA reversed the protective effects of CA. Thus, CA may be viewed as a potential drug to treat PQ-induced lung epithelial cell apoptosis and other disorders with similar pathologic mechanisms.

Beclin 1, LC3, and p62 expression in paraquat-induced pulmonary fibrosis

Paraquat (PQ) is a highly toxic herbicide to humans. Pulmonary fibrosis is one of the most typical features of PQ poisoning, which develops from several days to weeks after ingestion. However, the mechanism of fibrosis is still unclear. In this study, we aimed to determine expressions of autophagy-related markers Beclin 1, microtubule-associated protein light chain 3 (LC3), and p62 in PQ-poisoned lungs and to explore the role of autophagy in pulmonary fibrosis induced by PQ. We detected markers of lung fibrosis and expressions of autophagy-related protein in the specimens from eight fatal cases of PQ poisoning by hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemistry. Based on the staining results of lung fibrosis, these cases were divided into two groups, fibrosis and non-fibrosis groups. The correlation between autophagy protein expressions and pulmonary fibrosis was examined. The results demonstrated that the autophagy-related proteins were significantly expressed in fibrosis group compared with the non-fibrosis group. There was a significantly positive correlation between these protein expressions and severity of lung fibrosis. In conclusion, autophagy dysfunction may be involved in lung fibrogenesis caused by PQ poisoning. This may be a promising clue for understanding the molecular mechanism underlying PQ-induced lung fibrosis and provide evidence for treating fibrosis by regulating the level of autophagy.

Protective effects of febuxostat against paraquat-induced lung toxicity in rats: Impact on RAGE/PI3K/Akt pathway and downstream inflammatory cascades

AIMS

The herbicide paraquat causes fatal lung toxicity by induction of xanthine oxidase, production of free radicals and inflammation. Febuxostat, a xanthine oxidase inhibitor and anti-gout has recently shown anti-inflammatory activity. Accordingly, this study was carried out to investigate whether febuxostat may attenuate paraquat-induced lung toxicity and to explore the possible underlying mechanisms.

MAIN METHODS

Rats were administered either vehicle, a single dose of paraquat (30 mg/kg, i.p.), febuxostat (15 mg/kg, oral), or both for 14 successive days. Serum LDH and sRAGE were estimated. Lung tissue xanthine oxidase activity, SOD, TAC, MDA, and RAGE, HMGB1 gene expression, PI3K/Akt and β-catenin protein expression, MMP-9, IL-8, VEGF and COX-2 gene expression were estimated.

KEY FINDINGS

Results showed that paraquat induced lung injury characterized by enhanced oxidative stress and inflammation, upregulated RAGE, HMGB1 gene expression, PI3K/Akt and β-catenin protein expression. Administration of febuxostat inhibited the deleterious effects of paraquat on lung through inhibition of xanthine oxidase activity and related oxidative stress, downregulation of RAGE/PI3K/Akt pathway, and suppression of β-catenin protein expression and its downstream inflammatory mediators.

SIGNIFICANCE

The present study showed that febuxostat may abrogate paraquat-induced lung toxicity and demonstrated a novel mechanism for its ameliorative effects.

Probing into the Mechanism of Alkaline Citrus Extract Promoted Apoptosis in Pulmonary Fibroblasts of Bleomycin-Induced Pulmonary Fibrosis Mice

We extracted the primary pulmonary fibroblasts of the normal and bleomycin-induced pulmonary fibrosis mice and investigated the functioning mechanism of citrus alkaline extract (CAE) in the induction of pulmonary fibroblast apoptosis. The expression intensity of vimentin of the pulmonary fibroblasts in the model mice was higher than that in the normal mice. Meanwhile, the positive expression rate and expression intensity of alpha smooth muscle actin (α-SMA) of the pulmonary fibroblasts in the model mice were higher than those in the normal mice. Results of MTT showed that pulmonary fibroblast activity of the normal and model mice has been significantly inhibited by CAE in a concentration-dependent manner. The results of flow cytometer analysis showed that the proportion of pulmonary fibroblast apoptosis in the model mice has been profoundly increased by CAE treatment in a dosage-dependent manner. Besides we found that the expression of Cleaved-Caspase 3, Cleaved-Caspase 8, Cleaved-poly-ADP-ribose polymerase (Cleaved-PARP), and Fas and Fas Ligand (FasL) was markedly increased after CAE treatment. A further study showed that the expression of Cyclooxygenase-2 (COX-2) and prostaglandin E receptor 2 (EP2) was dependant on the concentration of CAE, indicating that CAE-regulated receptor apoptosis of Fas was probably related to COX-2. The results of fluorescence detection of oxidative stress showed that the level of oxidative stress was significantly increased after CAE treatment. Furthermore, the results of Western Blot showed that the phosphorylation level of p38 (p-p38) was markedly increased, suggesting that CAE probably has regulated COX-2 through increased p-p38 following oxidative stress. Our results therefore suggest that CAE can effectively induce pulmonary fibroblast apoptosis of the normal and model mice, and its functioning mechanism is probably related to the p38/COX-2/Fas signaling pathway regulated by oxidative stress.

A Damage Sensor Associated with the Cuticle Coordinates Three Core Environmental Stress Responses in Caenorhabditis elegans

Although extracellular matrices function as protective barriers to many types of environmental insult, their role in sensing stress and regulating adaptive gene induction responses has not been studied carefully...

Extracellular matrix barriers and inducible cytoprotective genes form successive lines of defense against chemical and microbial environmental stressors. The barrier in nematodes is a collagenous extracellular matrix called the cuticle. In Caenorhabditis elegans, disruption of some cuticle collagen genes activates osmolyte and antimicrobial response genes. Physical damage to the epidermis also activates antimicrobial responses. Here, we assayed the effect of knocking down genes required for cuticle and epidermal integrity on diverse cellular stress responses. We found that disruption of specific bands of collagen, called annular furrows, coactivates detoxification, hyperosmotic, and antimicrobial response genes, but not other stress responses. Disruption of other cuticle structures and epidermal integrity does not have the same effect. Several transcription factors act downstream of furrow loss. SKN-1/Nrf and ELT-3/GATA are required for detoxification, SKN-1/Nrf is partially required for the osmolyte response, and STA-2/Stat and ELT-3/GATA for antimicrobial gene expression. Our results are consistent with a cuticle-associated damage sensor that coordinates detoxification, hyperosmotic, and antimicrobial responses through overlapping, but distinct, downstream signaling.

Rapamycin protects against paraquat-induced pulmonary epithelial-mesenchymal transition via the Wnt/β-catenin signaling pathway

Paraquat (PQ) is a herbicide that is widely used in developing countries, and pulmonary fibrosisis one of the most typical features of PQ poisoning. The molecular mechanism underlying PQ toxicity is largely unknown, which makes it difficult to treat. In the present study, western blot analysis, reverse transcription-quantitative polymerase chain reaction and fluorescent immunostaining were used to analyze the effects of rapamycin on PQ-induced epithelial-mesenchymal transition (EMT) in A549 and MRC-5 cells. It was revealed that rapamycin significantly downregulated the mesenchymal cell marker, α-smooth muscle actin, and significantly upregulated the epithelial cell marker, E-cadherin, at mRNA and protein expression levels compared with the PQ group. Treatment with PQ significantly increased Wnt1, low-density lipoprotein receptor-related protein (LRP)5, LRP6 and β-catenin expression levels in A549 cells, while rapamycin significantly inhibited these effects of PQ. Activation of the Wnt signaling pathway using lithium chloride attenuated the inhibitory effects of rapamycin on PQ-induced EMT. In conclusion, rapamycin protects against PQ-induced pulmonary EMT via the Wnt/β-catenin signaling pathway.