A long-term follow-up of lung function in survivors of paraquat poisoning

The preventive effectiveness of Crocus sativus extract in treating lung injuries caused by inhaled paraquat in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The herbicide paraquat (PQ) is highly toxic, capable of inducing severe lung inflammation and oxidative stress, resulting in lung fibrosis and respiratory failure. Previous research has demonstrated a range of pharmacological effects associated with Crocus sativus. L (Cs) through its anti-inflammatory, antioxidant and immunomodulatory properties. Pharmacological studies support the widespread use of Cs in traditional medicine to treat respiratory disorders such as coughs and asthma.

AIM OF STUDY

This study aimed to investigate the preventive impact of Cs extract and pioglitazone (Pio) on lung inflammation, oxidative stress, pathological alterations, and tracheal reactivity induced by inhaled PQ in rats as compared to dexamethasone (Dexa).

METHODS

The control (Ctrl) group of rats was administered with saline aerosol, while the remaining six groups received PQ aerosol eight times every other day. The six PQ exposure groups were treated daily during the exposure period to PQ with either; saline alone, low dose Cs, High dose Cs, Pio alone, Pio combined with low dose Cs, or Dexa of 16 days.

RESULTS

In the PQ group, the levels of superoxide dismutase (SOD), catalase (CAT), and thiol in the bronchoalveolar lavage fluid (BALF) were declined whereas, the levels of MDA, total and differential WBC, and lung tissue levels of tumor necrosis factor (TNF-α) and Interleukin 10 (IL-10), tracheal responsiveness (TR) to methacholine and lung pathological changes were enhanced. The measured variables showed significant improvement in all treated groups, except for a few variables in Cs (L). The combined Cs (L) + Pio showed higher effects than Cs (L) and Pio alone. For all comparisons, p values were <0.05 to <0.001.

CONCLUSIONS

The results showed preventive effect of Cs comparable to that of Dexa and the potential additive preventive capabilities of the Cs and Pio indicate that the involvement of the PPARγ receptor is implicated in the effects induced by Cs.

Synaptotagmin-1 antagonizes paraquat intracellular accumulation and nephrocyte toxicity by up-regulating SERBP1/GLUT2 expression

Acute kidney injury (AKI) is common and an independent risk factor for mortality in patients with paraquat (PQ) poisoning. Currently, no specific antidote is available. Synaptotagmin-1 (SYT1) has been identified as a key protein that facilitates PQ efflux in PQ-resistant A549 cells, thereby preventing PQ-induced lung injury. However, the protective effect of STY1 on PQ-induced AKI remains to be elucidated. This study exposed human kidney 2 (HK-2) cells overexpressing SYT1 to PQ. These cells exhibited significantly lower levels of growth inhibition, reactive oxygen species production, early apoptosis, and PQ accumulation compared to the parent HK-2 cells. Transcriptomic screening and Western blot analysis revealed that SYT1 overexpression significantly promoted the expression of glucose transporter 2 (GLUT2). Inhibition of GLUT2 completely abolished the protective effects of SYT1 overexpression in HK-2 cells and restored intracellular PQ concentrations. Further immunoprecipitation-shotgun and RNA interference experiments revealed that SYT1 binds to and stabilizes the protein SERPINE1 mRNA-binding protein 1 (SERBP1), enhancing the stability of GLUT2 mRNA and its protein levels. In summary, SYT1 antagonizes PQ intracellular accumulation and prevents nephrocyte toxicity by up-regulating SERBP1/GLUT2 expression. This study identifies a potential target for the treatment of PQ-induced AKI.

Follow-up of patients with a 5-year survival after paraquat poisoning using computed tomography images and spirometry

OBJECTIVES

The study aimed to examine long-term survival of patients with acute paraquat poisoning using computed tomography (CT) images and spirometry.

METHODS

A total of 36 patients with long-term survival after paraquat poisoning were followed-up and divided into mild (11 patients), moderate (17 patients), and severe (8 patients) paraquat poisoning groups. Differences among the groups were compared using clinical indicators, such as peripheral capillary oxygen saturation, arterial partial pressure of oxygen and 6-min walk test (6-MWT), chest CT, spirometry, and serum immunoglobulin E (IgE).

RESULTS

The 6-MWT distance was significantly shorter in the severe paraquat poisoning group than that in the mild and moderate paraquat poisoning groups. In the mild paraquat poisoning group, CT revealed no obvious lung injury, and spirometry showed normal lung function in most patients. In moderate or severe paraquat poisoning group, CT images showed fibrotic lesions as cord-like high-density shadows, reticulations, and honeycombs. In addition, other pulmonary changes, including bronchiectasis, increased lung transparency, and pulmonary bullae, were discovered. In moderate or severe paraquat poisoning group, obvious obstructive ventilation dysfunction with slight restrictive and diffuse impairment were observed in some patients, with positive bronchial relaxation test and high serum IgE level.

CONCLUSION

In the long-term follow-up, patients with severe paraquat poisoning showed the lowest exercise endurance. In moderate or severe paraquat poisoning group, CT images revealed diversified changes, not only dynamic evolution of pulmonary fibrosis process, but also signs of bronchiectasis, and chronic obstructive pulmonary disease. Some patients with moderate or severe paraquat poisoning developed obstructive ventilatory dysfunction with airway hyperresponsiveness.

Pectin/chitosan/tripolyphosphate encapsulation protects the rat lung from fibrosis and apoptosis induced by paraquat inhalation

BACKGROUND

Paraquat poisoning leads to lung injury and pulmonary fibrosis. The effect of paraquat encapsulation by previously described Pectin/Chitosan/Tripolyphosphate nanoparticles on its pulmonary toxicity was investigated in present study in a rat model of poison inhalation.

MATERIAL AND METHOD

The rats inhaled nebulized different formulation of paraquat (n = 5) for 30 min in various experimental groups. Lung injury and fibrosis scores, Lung tissue enzymatic activities, apoptosis markers were determined compared among groups.

RESULTS

Encapsulation of paraquat significantly rescued both lung injury and fibrosis scores. Lung MDA level was reduced by encapsulation. Paraquat poisoning led to lung tissue apoptosis as was evidenced by higher Caspase-3 and Bax/Bcl2 expressions in rats subjected to paraquat inhalation instead of normal saline or free nanoparticles. Again, nanoencapsulation reduced these apoptosis markers significantly. Alpha-SMA expression was also reduced by encapsulation. Nanoparticles per se have no or little toxicity as was evidenced by inflammatory and apoptotic markers and histological scores.

CONCLUSION

In a rat model of inhalation toxicity of paraquat, loading of this herbicide on PEC/CS/TPP nanoparticles reduced acute lung injury and fibrosis. The encapsulation also led to lower apoptosis, oxidative stress and alpha-SMA expression in the lung tissue.

Endoplasmic reticulum stress promotes epithelial‑mesenchymal transition via the PERK signaling pathway in paraquat‑induced pulmonary fibrosis

Pulmonary fibrosis is the primary reason for mortality in patients with paraquat (PQ) poisoning. Our previous study demonstrated that epithelial-mesenchymal transition (EMT) had a role in PQ-induced pulmonary fibrosis. However, the role of endoplasmic reticulum (ER) stress in PQ-induced EMT remains clear. The present study aimed to determine the role of ER stress in EMT in PQ-induced pulmonary fibrosis. A549 and RLE-6TN cells were incubated with LY294002 (a PI3K inhibitor) or transfected with protein kinase RNA-like ER kinase (PERK) small interfering RNA (si) for 24 h prior to being exposed to PQ. Next, the expression levels of ER stress-related proteins, PI3K/AKT/GSK-3β signaling pathway-related proteins and EMT-related markers were analyzed by performing western blotting, reverse transcription-quantitative PCR and immunofluorescence assays. The results of the present study revealed that the protein expression levels of PERK, phosphorylated (p)-PERK, p-eukaryotic initiation factor 2 (eIF2)α were significantly upregulated in the PQ group, whereas p-PI3K, p-AKT and p-GSK-3β were significantly upregulated in the sicontrol + PQ group compared with the sicontrol group. In vitro, following transfection with siPERK or treatment with the PI3K inhibitor, the protein expression levels of E-cadherin (an epithelial marker) were upregulated, whereas the protein expression levels of α-SMA (a mesenchymal marker) were downregulated. Immunofluorescence analysis revealed that the levels of E-cadherin were markedly upregulated, whereas the levels of α-SMA were notably downregulated following transfection with siPERK compared with the sicontrol group. The results of wound healing assay demonstrated that cell migration in the siPERK + PQ group was markedly decreased compared with the sicontrol + PQ group. These indicated that PQ-induced EMT was suppressed after silencing PERK. The expression levels of p-GSK-3β, p-AKT and p-PI3K were also markedly downregulated in the siPERK + PQ group compared with the sicontrol + PQ group. In conclusion, the findings of the present study suggested that ER stress may promote EMT through the PERK signaling pathway in PQ-induced pulmonary fibrosis. Thus, ER stress may represent a potential therapeutic target for PQ-induced 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.

Long-term exposure to PM2.5 and Children's lung function: a dose-based association analysis

Background

The current literature is still not consist regarding the effect of long-term exposure to PM2.5 and children’s lung function, partly due to inadequate or inaccurate exposure assessment. In this study, we aim to investigate the associations between long-term exposure to PM2.5, estimated as average daily dose (ADD), and lung function in school-age children.

Methods

We recruited 684 participants of 7–12 years old from the city of Lanzhou located in northwestern China. Participants underwent spirometric tests for lung function and responded to a questionnaire survey. Detailed information about individual air exposure and personal information were collected, including length of school hours, home address, age, gender, etc. Combining the spatial distribution of PM2.5 concentrations in the past 5 years and individual time-activity data, we estimated annual ADD for 5 years preceding the lung function tests and 5-year average ADD, respectively. We used multiple linear regression models to examine the associations between ADD values and lung function, controlling for a range of individual-level covariates.

Results

The 5-year average ADD among all the participants was 50.5 µg/kg-d, with higher values estimated for children living in the urban area than the suburban area, for boys than girls, and for children whose parents received a lower education attainment. We found that a 1 μg/kg-d increment in ADD of PM2.5 was associated with a 10.49 mL (95% CI: −20.47, −0.50) decrease in forced vital capacity (FVC) and a 7.68 mL (95% CI: −15.80, −0.44) decrease in forced exploratory volume in 1 second (FEV₁). Among the annual ADDs estimated for the preceding 5 years, the immediate past year prior to lung function measurement had the greatest effect on lung function. The effect was greater in girls than in boys. We found no associations between annual exposure of PM2.5 (instead of ADD) and lung function when defined concentration was used as an exposure variable.

Conclusions

Long-term PM2.5 exposure, when estimated as exposure dose averaged over a year or longer, was associated with statistically significant reductions in FVC and FEV1 in children of elementary-school age. Future studies may consider the use of individual-level dose estimates (as opposed to exposure concentrations) to improve the dose-response assessment.

Effects of tacrolimus on the TGF‑β1/SMAD signaling pathway in paraquat‑exposed rat alveolar type II epithelial cells

Paraquat is a highly toxic pesticide, which often causes pulmonary interstitial fibrosis after poisoning, and there is no specific antidote. At present, limited studies have reported that tacrolimus, as an immunosuppressant, can inhibit pulmonary fibrosis, but the specific mechanism remains unknown. The aim of the present study was to demonstrate the effect of tacrolimus on the TGF-β1 pathway associated with pulmonary fibrosis in paraquat exposed alveolar type II epithelial cells, and to identify the antipulmonary fibrosis mechanism of tacrolimus The rat alveolar epithelial type II RLE-6TN cell line was exposed to paraquat and treated with or without tacrolimus for 24 h, or with a TGF-β1 receptor type I/II inhibitor (LY2109761) for 1, 4, 8 or 16 h. MTT assays were used to detect the viability of rat alveolar type II epithelial cells under these different treatment conditions, while the concentrations of TGF-β1, SMAD3, SMAD7 and connective tissue growth factor (CTGF) in the cell culture supernatant were determined using ELISAs. Additionally, reverse transcription-quantitative PCR and immunofluorescence were used to analyze the mRNA and protein expression levels of TGF-β1, SMAD3, CTGF and SMAD7. The results demonstrated that the inhibition of the proliferation of RLE-6TN cells exposed to 200 nmol/l paraquat was 26.05±2.99%. The inhibition rate of 10 ng/ml tacrolimus on paraquat-exposed alveolar type II epithelial cells was 18.40±3.49%. The inhibition rate caused by 5 µmol/l LY2109761 was 26.56±4.49%. The expression levels of TGF-β1, SMAD3 and CTGF, as well as their concentrations in the culture supernatant, were significantly downregulated in the tacrolimus group compared with the paraquat group. However, both the concentration and expression levels of SMAD7 were significantly upregulated in the tacrolimus group compared with the paraquat group. In conclusion, tacrolimus can reduce the levels of TGF-β1, SMAD3 and CTGF, increase the level of SMAD7 in TGF-β1 signaling pathway and protect the development of pulmonary fibrosis in paraquat exposed alveolar epithelial cells.

Burden of paraquat poisoning in the department of Antioquia, Colombia

Background

Paraquat (PQ) poisoning is a public health problem in many regions of Colombia. This study aimed to estimate the burden of PQ poisoning in the Department of Antioquia, Colombia.

Methods

Disability-adjusted life year (DALYs) were calculated as the sum of years of life lost (YLL) and years of life lived with disability (YLD) due to paraquat poisoning in Antioquia; a bootstrapped method with 1000 iterations was used to estimate each statistical parameter using the package DALY calculator in R. For this instance, the annual incidence of paraquat poisoning was obtained from the reported surveillance data according to regional Government.

Results

From 2010 to 2016, 3299 DALYs were estimated in the department of Antioquia for PQ intoxication, with a rate of 53.4 DALYs per 100,000 inhabitants. The majority of the DALYs (2852 DALYs) were generated for men ranging from 15 to 44 years old.

Conclusion

The rate of DALYs reported here is higher than that reported by all chemical poisonings. Better strategies to regulate and restrict the market of this dangerous products are required in Colombia.

Prolonged low-dose cyclophosphamide treatment after pulse therapy attenuates lung injury in rats with paraquat intoxication

BACKGROUND/AIMS

This study tested the hypothesis that prolonged low-dose cyclophosphamide (CTX) treatment after pulse therapy attenuate paraquat (PQ)-induced lung injury in rats.

METHODS

PQ (25 mg/kg) was administered intraperitoneally to induce PQ-intoxicated rat model. The rats were randomly divided into four groups: control group (1 mL/day saline solution for 14 days), PQ group (1 mL/day saline solution for 14 days after PQ exposure), pulse group (15 mg/kg/day CTX in 1 mL of saline solution for 2 days and subsequent 1 mL/day saline solution for 12 days), and prolonged low-dose group (15 mg/kg/day CTX in 1 mL of saline solution for 2 days and subsequent 1.5 mg/kg/day CTX in 1 mL of saline solution for 12 days). A 14-day follow-up was conducted to determine the survival rat, and lung hydroxyproline (HYP), wet-to-dry weight ratios (W/Dc) and histopathological changes were evaluated.

RESULTS

Results showed similar survival rate (55% vs. 50%, p > 0.05) between prolonged low-dose and pulse groups. Lung W/Dc (4.94 ± 0.38 vs. 5.47 ± 0.28, p < 0.01), HYP (3.34 ± 0.29 µg/mg vs. 3.65 ± 0.19 µg/mg, p < 0.001), and fibrosis score (2.69 ± 0.84 vs. 3.13 ± 0.63, p < 0.05) were lower in prolonged low-dose group than those in the pulse group.

CONCLUSION

These findings suggested prolonged low-dose CTX treatment after pulse therapy could attenuate PQ-induced lung injury in rats.

Lung injury caused by paraquat poisoning results in increased interleukin-6 and decreased microRNA-146a levels

The aim of the present study was to investigate the expression of microRNA (miR)-146a in the pulmonary macrophages, peripheral blood mononuclear cells and serum of patients with lung injury caused by paraquat poisoning, as well as the underlying mechanism of its regulation in the disease. A total of 26 patients with lung injury caused by paraquat poisoning were included in the present study. In addition, 33 healthy subjects were included as the control group. The expression levels of interleukin (IL)-6 mRNA and miR-146a was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Western blotting was used to measure IL-6 protein expression, while enzyme-linked immunosorbent assay was also performed to determine the secretion of IL-6 protein. A dual-luciferase reporter assay was conducted to examine whether IL-6 mRNA is a direct target of miR-146a. Patients with lung injury caused by paraquat poisoning exhibited higher IL-6 mRNA and protein levels as compared with those in healthy subjects. In addition, miR-146a expression in patients with paraquat poisoning-induced lung injury was significantly reduced in comparison with that in healthy subjects. Notably, the overexpression of miR-146a by mimic transfection downregulated the expression of IL-6 in pulmonary macrophages. The results of dual-luciferase reporter assay demonstrated that IL-6 mRNA was a direct target of miR-146a. Therefore, the present study demonstrated that increased expression of IL-6 in patients with lung injury caused by paraquat poisoning is associated with decreased expression of miR-146a. Furthermore, miR-146a may regulate the occurrence and immune response of lung injury caused by paraquat poisoning and this process is possibly achieved via IL-6, an important cytokine that mediates inflammation.

Patients with mild paraquat poisoning treated with prolonged low-dose methylprednisolone have better lung function: A retrospective analysis

Lung dysfunction is an important characteristic of injury induced by paraquat (PQ). This study aimed to evaluate the effects of prolonged low-dose methylprednisolone (MP) treatment on lung function in patients with mild PQ poisoning. We analyzed the results of lung function testing in all patients with mild PQ poisoning admitted to Cangzhou Central Hospital between January 2012 and August 2017. Patients were grouped according to short-term treatment (3 mg/kg/day MP for 3 days) or prolonged treatment (3 mg/kg/day MP for 3 days, followed by dosage reduction by half every 3 days, with treatment terminated when a dosage of 0.375 mg/kg/day was reached). Lung function was evaluated at 2 to 3 months after PQ exposure. The forced expiratory volume in 1 second (85.72 ± 4.93% vs 78.41 ± 4.58%; P < .001), forced vital capacity (81.98 ± 4.93% vs 77.85 ± 4.37%; P < .001), and diffusing capacity (84.27 ± 5.16% vs 76.21 ± 3.71%; P < .001) in the prolonged low-dose MP group were improved compared with those in the short-term MP group. Patients with mild PQ poisoning treated with prolonged low-dose MP had better lung function 2 to 3 months after PQ poisoning.

Porous Se@SiO2 nanocomposites protect the femoral head from methylprednisolone-induced osteonecrosis

Background

Methylprednisolone (MPS) is an important drug used in therapy of many diseases. However, osteonecrosis of the femoral head is a serious damage in the MPS treatment. Thus, it is imperative to develop new drugs to prevent the serious side effect of MPS.

Methods

The potential interferences Se@SiO₂ nanocomposites may have to the therapeutic effect of methylprednisolone (MPS) were evaluated by classical therapeutic effect index of acute respiratory distress syndrome (ARDS), such as wet-to-dry weight ratio, inflammatory factors IL-1β and TNF-α. And oxidative stress species (ROS) index like superoxide dismutase (SOD) and glutathione (GSH) were tested. Then, the protection effects of Se@SiO₂ have in osteonecrosis of the femoral head (ONFH) were evaluated by micro CT, histologic analysis and Western-blot analysis.

Results

In the present study, we found that in the rat model of ARDS, Se@SiO₂ nanocomposites induced SOD and GSH indirectly to reduce ROS damage. The wet-to-dry weight ratio of lung was significantly decreased after MPS treatment compared with the control group, whereas the Se@SiO₂ did not affect the reduced wet-to-dry weight ratio of MPS. Se@SiO₂ also did not impair the effect of MPS on the reduction of inflammatory factors IL-1β and TNF-α, and on the alleviation of structural destruction. Furthermore, micro CT and histologic analysis confirmed that Se@SiO₂ significantly alleviate MPS-induced destruction of femoral head. Moreover, compared with MPS group, Se@SiO₂ could increase collagen II and aggrecan, and reduce the IL-1β level in the cartilage of femoral head. In addition, the biosafety of Se@SiO₂ in vitro and in vivo were supported by cell proliferation assay and histologic analysis of main organs from rat models.

Conclusion

Se@SiO₂ nanocomposites have a protective effect in MPS-induced ONFH without influence on the therapeutic activity of MPS, suggesting the potential as effective drugs to avoid ONFH in MPS therapy.

Eukaryotic translation initiation factor 2 subunit α (eIF2α) inhibitor salubrinal attenuates paraquat-induced human lung epithelial-like A549 cell apoptosis by regulating the PERK-eIF2α signaling pathway

Paraquat (PQ), as one of the most widely used herbicides in the world, can cause severe lung damage in humans and animals. This study investigated the underlying molecular mechanism of PQ-induced lung cell damage and the protective role of salubrinal. Human lung epithelial-like A549 cells were treated with PQ for 24h and were pre-incubated with salubrinal for 2h, followed by 500μM of PQ treatment. Silencing eIF2α gene of the A549 cells with siRNA interference method was conducted. Cell morphology, cell viability, apoptosis and caspase-3 activity were assessed by different assays accordingly thereafter. The expression of PERK, p-PERK, ATF6, c-ATF6, IRE1α, p-IRE1α, CHOP, GRP78, p-eIF2α and β-actin was assayed by western blot. The data showed that PQ significantly reduced A549 cell viability, changed cell morphology, induced cell apoptosis and significantly upregulated the levels of GRP78, CHOP, p-PERK, c-ATF6 and p-IRE1α. However, 30μM salubrinal could attenuate the effects of PQ on damages to A549 cells through upregulating p-eIF2α. In contrast, knocking down eIF2α gene inhabited the effects of salubrinal. These results suggest that PQ-induced A549 cell apoptosis involved endoplasmic reticulum (ER) stress, specially the PERK-eIF2α pathway. Salubrinal attenuated A549 cells from PQ-induced damages through regulation of the PERK-eIF2α signaling.

Porous Se@SiO2 nanospheres treated paraquat-induced acute lung injury by resisting oxidative stress

Acute paraquat (PQ) poisoning is one of the most common forms of pesticide poisoning. Oxidative stress and inflammation are thought to be important mechanisms in PQ-induced acute lung injury (ALI). Selenium (Se) can scavenge intracellular free radicals directly or indirectly. In this study, we investigated whether porous Se@SiO₂ nanospheres could alleviate oxidative stress and inflammation in PQ-induced ALI. Male Sprague Dawley rats and RLE-6TN cells were used in this study. Rats were categorized into 3 groups: control (n=6), PQ (n=18), and PQ + Se@SiO₂ (n=18). The PQ and PQ + Se@SiO₂ groups were randomly and evenly divided into 3 sub-groups according to different time points (24, 48 and 72 h) after PQ treatment. Porous Se@SiO₂ nanospheres 1 mg/kg (in the PQ + Se@SiO₂ group) were administered via intraperitoneal injection every 24 h. Expression levels of reduced glutathione, malondialdehyde, superoxide dismutase, reactive oxygen species (ROS), nuclear factor-κB (NF-κB), phosphorylated NF-κB (p-NF-κB), tumor necrosis factor-α and interleukin-1β were detected, and a histological analysis of rat lung tissues was performed. The results showed that the levels of ROS, malondialdehyde, NF-κB, p-NF-κB, tumor necrosis factor-α and interleukin-1β were markedly increased after PQ treatment. Glutathione and superoxide dismutase levels were reduced. However, treatment with porous Se@SiO₂ nanospheres markedly alleviated PQ-induced oxidative stress and inflammation. Additionally, the results from histological examinations and wet-to-dry weight ratios of rat lung tissues showed that lung damage was reduced after porous Se@SiO₂ nanosphere treatment. These data indicate that porous Se@SiO₂ nanospheres may reduce NF-κB, p-NF-κB and inflammatory cytokine levels by inhibiting ROS in PQ-induced ALI. This study demonstrates that porous Se@SiO₂ nanospheres may be a therapeutic method for use in the future for PQ poisoning.

Suberoylanilide hydroxamic acid attenuates paraquat-induced pulmonary fibrosis by preventing Smad7 from deacetylation in rats

BACKGROUND

Recent evidence suggests that a histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), has anti-fibrotic effect. However, the exact mechanism of its anti-fibrotic potential remains is unclear. In this study, we investigated the molecular mechanism of SAHA in attenuating pulmonary fibrosis by regulating stability of Smad7 in paraquat (PQ)-induced lung fibrosis animal model and cultured pulmonary fibroblasts.

METHODS

Rats with paraquat-induced lung fibrosis were fed with a SAHA solution (15 mg/kg) by gastric gavage. Human pulmonary fibroblasts (HFL1) pre-treated with TGF-β1 (5 ng/mL) were treated with SAHA (5 µM).

RESULTS

SAHA (histone deacetylase inhibitor, HDACi) suppressed PQ-induced lung fibrosis in rats by stabilizing Smad7 level, thus attenuating Smad3 activity, resulting in the inhibition of fibroblast differentiation and collagen expression. In vitro study showed that SAHA suppressed TGF-β1-induced fibroblast differentiation into myofibroblasts. SAHA exerted its antifibrotic effect through preventing Smad7 from deacetylation most maybe by inhibiting TGF-β1-induced HDAC1 activity.

CONCLUSIONS

SAHA repressed PQ-induced lung fibrosis via preventing Smad7 from deacetylation.

Pyrrolidine dithiocarbamate attenuates paraquat-induced acute pulmonary poisoning in vivo via transforming growth factor β1 and nuclear factor κB pathway interaction

Paraquat (PQ) exposure could cause pulmonary fibrosis. The aim of this study was to investigate the protective effect of pyrrolidine dithiocarbamate (PDTC) in an acute PQ poison model. One hundred and forty-four Sprague Dawley rats were equally divided into three experimental groups: control group, PQ group, and PQ + PDTC group. At days 1, 3, 7, 14, 28, and 56 of treatment, the serum levels of transforming growth factor β1 (TGF-β1), the levels of hydroxyproline, the protein expression of nuclear factor κB (NF-κB) pathway, and histopathological change in lung tissue were assessed. The survival rate of rats treated with PQ + PDTC was increased compared with that of rats treated only with PQ (p < 0.05), and the occurrence of pathological changes was dramatically attenuated in the PQ + PDTC group. The serum levels of TGF-β1 and the hydroxyproline levels in the PQ group were significantly increased in a time-dependent manner compared with those in the control and PQ + PDTC groups on days 7, 14, 28, and 56 (p < 0.05). Additionally, the protein levels of NF-κB proteins p65, inhibitor of κB (IκB) kinase (IKKβ, and IκB-α were significantly downregulated in the PQ + PDTC group as determined by array analysis. The present findings suggest that overexpression of TGF-β1 may play an important role in PQ-induced lung injury and that PDTC, a strong NF-κB inhibitor, can rescue PQ-induced pulmonary fibrosis by influencing the protein expression of NF-κB pathway.

Adiponectin attenuates lung fibroblasts activation and pulmonary fibrosis induced by paraquat

Pulmonary fibrosis is one of the most common complications of paraquat (PQ) poisoning, which demands for more effective therapies. Accumulating evidence suggests adiponectin (APN) may be a promising therapy against fibrotic diseases. In the current study, we determine whether the exogenous globular APN isoform protects against pulmonary fibrosis in PQ-treated mice and human lung fibroblasts, and dissect the responsible underlying mechanisms. BALB/C mice were divided into control group, PQ group, PQ + low-dose APN group, and PQ + high-dose APN group. Mice were sacrificed 3, 7, 14, and 21 days after PQ treatment. We compared pulmonary histopathological changes among different groups on the basis of fibrosis scores, TGF-β₁, CTGF and α-SMA pulmonary content via Western blot and real-time quantitative fluorescence-PCR (RT-PCR). Blood levels of MMP-9 and TIMP-1 were determined by ELISA. Human lung fibroblasts WI-38 were divided into control group, PQ group, APN group, and APN receptor (AdipoR) 1 small-interfering RNA (siRNA) group. Fibroblasts were collected 24, 48, and 72 hours after PQ exposure for assay. Cell viability and apoptosis were determined via Kit-8 (CCK-8) and fluorescein Annexin V-FITC/PI double labeling. The protein and mRNA expression level of collagen type III, AdipoR1, and AdipoR2 were measured by Western blot and RT-PCR. APN treatment significantly decreased the lung fibrosis scores, protein and mRNA expression of pulmonary TGF-β₁, CTGF and α-SMA content, and blood MMP-9 and TIMP-1 in a dose-dependent manner (p<0.05). Pretreatment with APN significantly attenuated the reduced cell viability and up-regulated collagen type III expression induced by PQ in lung fibroblasts, (p<0.05). APN pretreatment up-regulated AdipoR1, but not AdipoR2, expression in WI-38 fibroblasts. AdipoR1 siRNA abrogated APN-mediated protective effects in PQ-exposed fibroblasts. Taken together, our data suggests APN protects against PQ-induced pulmonary fibrosis in a dose-dependent manner, via suppression of lung fibroblast activation. Functional AdipoR1 are expressed by human WI-38 lung fibroblasts, suggesting potential future clinical applicability of APN against pulmonary fibrosis.

The role of p38 MAPK in acute paraquat-induced lung injury in rats

CONTEXT

Paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridinium dichloride) is highly toxic and accounts for a large proportion of the herbicide poisonings seen in clinic. The major cause of mortality is respiratory failure. The p38 mitogen-activated protein kinase (MAPK) signal transduction pathway coordinates various cellular stress responses that have been shown to participate in the pathogenesis of PQ-induced lung injury.

OBJECTIVE

To evaluate the effect of the specific p38 MAPK inhibitor SB203580 on PQ-induced lung injury and cytokine secretion.

METHODS

In groups of 24, rats were treated with PQ, PQ and SB203580 (SB + PQ), SB203580 alone (SB) or normal saline (control group). Six rats from each group were euthanized at 1, 3, 5 or 7 d. Pathology of lung specimens was scored through hematoxylin and eosin staining. Edema in the lung was quantified from wet-to-dry weight ratios. p38 and p-p38MAPK proteins were measured via electrochemiluminescent Western blots. tumor necrosis factor (TNF)-alpha and interleukin-1 beta (IL-1β) concentrations in lung specimens and bronchoalveolar lavage fluid (BALF) were quantified via enzyme-linked immunosorbent assay.

RESULTS

The mortality rate of the SB + PQ group (16.7%) was significantly lower than that of the PQ group (33.3%; p < 0.05). The PQ group had significantly higher pulmonary histology scores, wet-to-dry weight ratios and phosphorylated p-p38 MAPK levels, as well as higher IL-1β and TNF-alpha levels in BALF and lung tissues, that did the SB + PQ and control groups (p < 0.05, all).

CONCLUSION

The data suggest that the p38 MAPK signaling pathway has an important role in regulating the production of IL-1β and TNF-alpha in PQ-induced lung injury in rats.

Losartan attenuates paraquat-induced pulmonary fibrosis in rats

Paraquat (PQ) is one of the most widely used herbicides in the world and can cause pulmonary fibrosis in the cases with intoxication. Losartan, an angiotensin II type 1 receptor antagonist, has beneficial effects on the treatment of fibrosis. The aim of this study was to examine the effect of losartan on pulmonary fibrosis in PQ-intoxicated rats. Adult male Sprague Dawley rats (n = 32, 180-220 g) were randomly assigned to four groups: (i) control group; (ii) PQ group; (iii) PQ + losartan 7d group; and (iv) PQ + losartan 14d group. Losartan treatment (intragastrically (i.g.), 10 mg/kg) was performed for 7 and 14 days after a single i.g. dose of 40 mg/kg PQ. All rats were killed on the 16th day, and hematoxylin-eosin and Masson's trichrome staining were used to examine lung injury and fibrosis. The levels of hydroxyproline and transforming growth factor β1 (TGF-β1), matrix metallopeptidase 9 (Mmp9), and tissue inhibitor of metalloproteinase 1 (TIMP-1) messenger RNA (mRNA) expression and relative expression levels of collagen type I and III were also detected. PQ caused a significant increase in hydroxyproline content, mRNA expression of TGF-β1, Mmp9, and TIMP-1, and relative expression levels of collagen type I and III ( p < 0.05), while losartan significantly decreased the amount of hydroxyproline and downregulated TGF-β1, Mmp9, and TIMP-1 mRNA and collagen type I and III expressions ( p < 0.05). Histological examination of PQ-treated rats showed lung injury and widespread inflammatory cell infiltration in the alveolar space and pulmonary fibrosis, while losartan could markedly reduce such damage and prevent pulmonary fibrosis. The results of this study indicated that losartan could reduce lung damage and prevent pulmonary fibrosis induced by PQ.

FTY720 attenuates paraquat-induced lung injury in mice

Paraquat (PQ) poisoning, with the lung as a primary target organ, is a devastating disease which irreversibly progresses to diffuse alveolitis followed by extensive lung fibrosis. In the present study, we aimed to investigate the effect of FTY720, an immune modulator, on PQ-induced lung injury in mice. C57BL/6 mice were randomized into four groups: 1) PQ group (n=12): mice was instilled with PQ (30 mg/kg, ip); 2) PQ+FTY720 group (n=12): animals received FTY720 (0.1mg/kg, ip) solution 2h after PQ exposure and twice a week for 4 consecutive weeks; 3) FTY720 group (n=5): FTY720 (0.1mg/kg, ip) was administrated twice a week for 4 consecutive weeks; and 4) Control group (n=10): same volumes of saline were injected. Mice were sacrificed on either day 3 or day 28 for histopathological, biochemical and immunohistochemical analyses of lung damage indicators. We found that FTY720 treatment attenuated PQ-induced acute lung injury and lung fibrosis as evaluated by histopathological changes and Ashcroft score. On day 3, FTY720 administration reduced PQ-induced increases in lung wet weight/body weight (LW/BW), total protein and cytokine levels including interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in bronchoalceolar lavage fluid (BALF). On day 28, the expressions of alpha-smooth muscle actin (α-SMA), transforming growth factor-beta (TGF-β) and vascular endothelial growth factor (VEGF) detected by immunohistochemistry, as well as the mRNA levels of α-SMA, Type-I Collagen and Type-III Collagen examined by Real-time PCR were down-regulated after FTY720 treatment. These results indicate that FTY720 could attenuate PQ-induced lung injury, but further investigation is necessary.

Paraquat poisoning: A case report and review of literature

Paraquat (1, r-dimethyl-4,4’-bipyridium dichloride), a brown syrupy liquid is an effective herbicide that has low chronic toxicity because of its rapid deactivation on contact with soil. A high dose of paraquat or severe poisoning has a poor prognosis. At present there is no specific antidote to paraquat poisoning, hence the need to focus on prevention and in case of exposure or ingestion, aggressive decontamination to prevent further absorption. Although uncommon, paraquat ingestion can lead to severe and often fatal toxicity. However, despite its widespread availability, reports of this herbicide poisoning in India are uncommon.

Paraquat increases connective tissue growth factor expression and impairs lung fibroblast proliferation and viscoelasticity

This in vitro study was designed to investigate the molecular mechanisms of paraquat-induced damage using cultured human fetal lung fibroblasts (MRC-5 cells), in order to promote the development of improved therapies for paraquat poisoning. Paraquat’s effects on proliferation were examined by flow cytometry, on viscoelasticity by the micropipette aspiration technique, and on connective tissue growth factor (CTGF) expression by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Paraquat was found to significantly reduce the proliferation index of MRC-5 cells in a concentration-dependent manner ( p < 0.05) and to significantly impair the viscoelastic properties in a time-independent manner ( p < 0.05). Exposure to paraquat led to a significant and time-dependent increase in CTGF expression ( p < 0.05) and induced changes in the morphology and biomechanical characteristics of the MRC-5 cells. These findings not only provide novel insights into the mechanisms of paraquat-induced lung fibrosis but may represent useful targets of improved molecular-based therapies for paraquat poisoning.

Effect of transforming growth factor-β1 on acute lung injury caused by paraquat

In China, and other Asian countries, numerous patients have succumbed to pulmonary fibrosis induced by paquarat poisoning, but the early pathogenesis remains unclear. In this study the effect of cytokine transforming growth factor (TGF)-β1 was observed in early acute paraquat poisoning and examined the mechanism by which paraquat caused early acute lung injury. It was discovered that the rat serum TGF-β1 levels in the paraquat groups were significant higher than that in the control group (P<0.05) and the rat pulmonary TGF-β1 mRNA expression levels were also higher than that in the control group (P<0.05). Histological examination indicated that the rat lung tissue was broad and congested, and had been infiltrated by inflammatory cells. Masson's trichrome staining for collagen showed that the lung tissue appeared fibrotic following paraquat poisoning. Ultramicrostructure observation found that macrophages, red blood cells, lymphocytes and granulocytes infiltrated the alveolar space and there were cytolysosomes in the macrophages. The shape of the type II alveolar epithelial cell nuclei were irregular with karyopyknosis. The heterochromatin migrated to the cell edge and lamellar body vacuolization was also observed. Type I alveolar epithelial cells shrank. In conclusion, the effect of cytokine TGF-β1 on paraquat-induced acute lung tissue injury may be important.

Addition of immunosuppressive treatment to hemoperfusion is associated with improved survival after paraquat poisoning: a nationwide study

Paraquat poisoning associates very high mortality rate. Early treatment with hemoperfusion is strongly suggested by animal and human studies. Although the survival benefit of additional immunosuppressive treatment (IST) in combination with hemoperfusion is also reported since 1971, the large-scale randomized control trials to confirm the effects of IST is difficult to be executed. Therefore, we designed this nationwide large-scale population-based retrospective cohort study to investigate the outcome of paraquat poisoning with hemoperfusion and the additional effects of IST combined with hemoperfusion. This nationwide retrospective cohort study utilized data retrieved from the National Health Insurance Research Database (NHIRD) of Taiwan. A total of 1811 hospitalized patients with a diagnosis of paraquat poisoning who received hemoperfusion between 1997 and 2009 were enrolled. The mean age of all 1811 study subjects was 47.3 years. 70% was male. The overall survival rate was only 26.4%. Respiratory failure and renal failure were diagnosed in 56.2% and 36% patients. The average frequency of hemoperfusion was twice. IST was added in 42.2% patients. IST significantly increases survival rate (from 24.3% to 29.3%, P<0.001). The combined IST with methylprednisolone, cyclophosphamide and dexamethasone associates with the highest survival rate (48%, P<0.001). Moreover, patients younger than 45 years of age in the IST group had the best survival (41.0% vs. 33.7%, p<0.001). Our results support the use of IST with hemoperfusion for paraquat-poisoned patients. The best survival effect of IST is the combination of methylprednisolone, cyclophosphamide and daily dexamethasone, especially in patients with younger age.

Antifibrotic effect of atorvastatin on paraquat-induced pulmonary fibrosis: role of PPARγ receptors

This study was carried out to highlight the role of PPARγ in the paraquat (PQ)-induced pulmonary fibrosis. Forty-two male Wistar rats were exposed either against saline as a control group or PQ (3.5mg/kg, i.p.) as test groups. The test groups were nominated as PQ (PQ-exposed non-treated animals), pioglitazone (PGT, 10mg/kg, orally), atorvastatin (STN, 10mg/kg, orally), PGT+STN, PGT+GW9662 (1mg/kg, i.p.) and STN+GW9662 (1mg/kg). Atorvastatin but not PGT was able to reverse significantly (P<0.05) the PQ-increased ratio of lung to body weight. STN was successfully able to recover the PQ-reduced antioxidant potency and the GW9662 administration resulted in antagonizing the protective effect of both PGT and STN. Although both PGT and STN were able to reduce the hydrxoproline content of the lungs, GW9662, however, could reverse only STN-related effect. Histochemical studies revealed that PQ exposure resulted in a remarkable increase of fibroblasts and collagen fibers in the interstitial tissue and around vessels and bronchioles, which was improved by the STN administration. Only STN-received animals showed the down-regulation of the TGF-β1 expression and GW9662 was able to antagonize this down-regulation. Co-administration of PGT and STN could not exert any synergistic protective effect. These data suggest that the PQ-induced pulmonary fibrosis could be more effectively reversed by STN rather than PGT. Moreover, STN-induced protective effects might attribute to the regulation of TGF-β1 expression, which is antagonized by PPARγ antagonist, suggesting that STN may improve the PQ-induced damages via PPARγ.

Delayed immunosuppressive treatment in life-threatening paraquat ingestion: a case report

INTRODUCTION

Combined glucocorticoids and cyclophosphamide pulse therapy showed promising results in moderate-to-severe paraquat poisonings to reduce life-threatening respiratory complications. Its benefit has been observed when given early in the course of poisoning; however, whether its delayed administration remains beneficial is unknown.

CASE REPORT

We describe a 23-year-old male who ingested 70 mL of a commercialized concentrate formulation with 20% weight/volume paraquat in a suicide attempt. Within 24 hours from paraquat ingestion, he presented most of the indicators of poor outcome, including gastritis, early renal dysfunction, dark blue urine colorimetric dithionite test, and marked plasma paraquat concentrations (0.56 microg/mL at 13 hours, and 0.41 microg/mL at 24 hours after ingestion). The patient received early gastrointestinal decontamination and aggressive supportive treatments. However, due to a rapidly progressive severe pulmonary infection, glucocorticoids and cyclophosphamide were delayed until day 14. Interestingly, our patient survived with mild respiratory sequelae despite poor initial prognosis.

DISCUSSION

This observation suggests the potential benefit of immunosuppressive pulse therapy, even if administered 14 days after paraquat ingestion, and highlights the role of paraquat-induced alveolitis in the development of fibrosis.

CONCLUSION

Combined glucocorticoids and cyclophosphamide should be considered in moderate-to-severe paraquat poisonings, even if delayed.

Pyrrolidine dithiocarbamate attenuates paraquat-induced lung injury in rats

Paraquat (PQ) has been demonstrated that the main target organ for the toxicity is the lung. This study aimed to investigate the potential protective effect of PDTC on the PQ-induced pulmonary damage. Fifty-four rats were divided into control, PQ-treated and PQ+PDTC-treated groups. Rats in the PQ group were administrated 40 mg/kg PQ by gastric gavage, and PDTC group with 40 mg/kg PQ followed by injection of 120 mg/kg PDTC (IP). On the days 3, 7, 14 and 21 after treatments, the activities of GSH-Px, SOD, MDA level and the content of HYP were measured. TGF-β1 mRNA and protein were assayed by RT-PCR and ELISA. MDA level in plasma and BALF was increased and the activities of GSH-Px and SOD were decreased significantly in the PQ-treated groups (P < .05) compared with control group. While the activities of GSH-Px and SOD in the PQ+PDTC-treated groups was markedly higher than that of PQ-treated groups (P < .05), and in contrast, MDA level was lower. TGF-β1 mRNA and protein were significantly lower in the PQ+PDTC-treated groups than that of PQ-treated groups (P < .05). The histopathological changes in the PQ+PDTC-treated groups were milder than those of PQ groups. Our results suggested that PDTC treatment significantly attenuated paraquat-induced pulmonary damage.

Marked recovery from paraquat-induced lung injury during long-term follow-up

BACKGROUND/AIMS

Paraquat-induced lung injury has been considered a progressive and irreversible disease. The purpose of this study was to report the long-term evolution of lung lesions in eight survivors with significant paraquat-induced lung injuries who could be followed-up for longer than 6 months.

METHODS

We retrospectively examined high-resolution computed tomography and pulmonary function test of eight survivors with significant paraquat-induced lung injurys.

RESULTS

High-resolution computed tomography revealed a predominant pattern of irregularly shaped consolidation with traction bronchiectasis at 1-2 months after paraquat poisoning, a mixed pattern of irregularly shaped consolidation and ground-glass opacity at 3-12 months, and a mixed pattern of consolidation, ground-glass opacity, and honeycombing at 1-2 years. At 3-12 months after paraquat ingestion, the areas of consolidation had markedly decreased and the decreased lung volume had returned to normal. At 1-2 years after paraquat poisoning, the cystic changes had disappeared. At 2-3 years after paraquat poisoning, the decrease in forced vital capacity had greatly improved to the normal range.

CONCLUSIONS

Recovery of nearly normal pulmonary structure and function may occur over several years following paraquat poisoning. Pulmonary function (both forced vital capacity and forced expiratory volume in 1 sec) evolved toward normal in the long-term survivors of paraquat poisoning with initial prominent lung injuries.

Low level of exposure to pesticides leads to lung dysfunction in occupationally exposed subjects

Pesticides may contribute to adverse respiratory health effects among farmers and have been considered one causal factor for the rise in asthma prevalence. This cross-sectional study was conducted to evaluate potential respiratory function abnormalities following long-term pesticide exposure by means of a complete pulmonary function testing, including spirometry, lung volumes, and diffusing capacity for carbon monoxide. The study population was comprised by workers from a prominent intensive agriculture area of southern Spain that relied on pesticides for the control of plagues. Eighty-nine pesticide sprayers of plastic greenhouse farming and a control group of 25 nonspraying control farmers from the same area were interviewed by a general practitioner asking about sociodemographic factors, occupational exposure, and clinical symptoms by using a structured questionnaire. Multiple regression analyses showed a relationship of short-term exposure to pesticides (as indicated by a drop in serum cholinesterase > 25% of baseline levels) with reduced forced expired volume in 1 s, and of long-term exposure (as indicated by a cumulative pesticide exposure index) with reduced forced expiratory flow rate. Exposure to bipyridilium-class herbicides was a determinant of a fall in the diffusing capacity of the lungs, and neonicotinoid insecticides showed a relationship with lower pulmonary volumes (total lung capacity, residual volume, and functional residual capacity), suggestive of restrictive lung disease, and with an increased risk of reporting irritative symptoms.

Paraquat poisonings: mechanisms of lung toxicity, clinical features, and treatment

Paraquat dichloride (methyl viologen; PQ) is an effective and widely used herbicide that has a proven safety record when appropriately applied to eliminate weeds. However, over the last decades, there have been numerous fatalities, mainly caused by accidental or voluntary ingestion. PQ poisoning is an extremely frustrating condition to manage clinically, due to the elevated morbidity and mortality observed so far and due to the lack of effective treatments to be used in humans. PQ mainly accumulates in the lung (pulmonary concentrations can be 6 to 10 times higher than those in the plasma), where it is retained even when blood levels start to decrease. The pulmonary effects can be explained by the participation of the polyamine transport system abundantly expressed in the membrane of alveolar cells type I, II, and Clara cells. Further downstream at the toxicodynamic level, the main molecular mechanism of PQ toxicity is based on redox cycling and intracellular oxidative stress generation. With this review we aimed to collect and describe the most pertinent and significant findings published in established scientific publications since the discovery of PQ, focusing on the most recent developments related to PQ lung toxicity and their relevance to the treatment of human poisonings. Considerable space is also dedicated to techniques for prognosis prediction, since these could allow development of rigorous clinical protocols that may produce comparable data for the evaluation of proposed therapies.

Transforming growth factor-β1 upregulation is independent of angiotensin in paraquat-induced lung fibrosis

Transforming growth factor-beta1 (TGF-beta1) contributes to the fibrosis of injured organs. Angiotensin II (Ang II) is an inducer of TGF-beta1 in cells of the heart and kidneys, and the regulation of TGF-beta1 by Ang II has not yet been confirmed in lung tissue. We evaluated the role of TGF-beta1 and its relationship with Ang II in paraquat-induced lung fibrosis. Adult male Sprague-Dawley rats were treated intraperitoneally with paraquat (20mg/kg) or saline in the control group. On days 1, 3, 7, and 21 after paraquat treatment, TGF-beta1 and collagen gene expressions, TGF-beta1 protein, angiotensin-converting enzyme (ACE) activity, Ang II, and hydroxyproline contents were measured in lung tissue. Lung TGF-beta1 mRNA expression progressively increased and reached a peak on day 7 after paraquat treatment. Increases in TGF-beta1 mRNA expression and TGF-beta1 levels preceded the onset of increased collagen I mRNA expression and hydroxyproline contents. c-myc mRNA expressions were inversely correlated with TGF-beta1 protein levels in paraquat-treated lungs. Lung ACE activity decreased after paraquat administration and the decrement was maximal on day 7. Lung Ang II concentrations immediately decreased after paraquat administration and the values were not related to TGF-beta1 levels. We conclude that TGF-beta1 is upregulated and contribute to the paraquat-induced lung fibrosis and this effect is independent of the renin-angiotensin system.