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

Unraveling Paraquat-Induced Toxicity on Mouse Neural Stem Cells: Dose-Response Metabolomics Insights and Identification of Sensitive Biomarkers for Risk Assessment

Exposure to pesticide could contribute to neurodevelopmental and neurodegenerative disorders. Notably, research suggests that prenatal or early postnatal exposure to paraquat (PQ), an herbicide, might trigger neurodevelopmental toxicity in neural stem cells (NSCs) via oxidative stress. However, the molecular mechanisms of PQ-induced perturbations in NSCs, particularly at the metabolite level, are not fully understood. Using a dose-response metabolomics approach, we examined metabolic changes in murine NSCs exposed to different PQ doses (0, 10, 20, 40 μM) for 24h. At 20 μM, PQ treatment led to significant metabolic alterations, highlighting unique toxic mechanisms. Metabolic perturbations, mainly affecting amino acid metabolism pathways (e.g., phenylalanine, tyrosine, arginine, tryptophan, and pyrimidine metabolism), were associated with oxidative stress, mitochondrial dysfunction, and cell cycle dysregulation. Dose-response models were used to identify potential biomarkers (e.g., Putrescine, L-arginine, ornithine, L-histidine, N-acetyl-L-phenylalanine, thymidine) reflecting early damage from low-dose PQ exposure. These biomarkers could be used as points of departure (PoD) for characterizing PQ exposure hazard in risk assessment. Our study offers insights into mechanisms and risk assessment related to PQ-induced neurotoxicity in NSCs.

YAP/TAZ activation mediates PQ-induced lung fibrosis by sustaining senescent pulmonary epithelial cells

Paraquat (PQ) is a widely used herbicide and a common cause of poisoning that leads to pulmonary fibrosis with a high mortality rate. However, the underlying mechanisms of PQ-induced pulmonary fibrosis and whether pulmonary epithelial cell senescence is involved in the process remain elusive. In this study, PQ-induced pulmonary epithelial cell senescence and Hippo-YAP/TAZ activation were observed in both C57BL/6 mice and human epithelial cells. PQ-induced senescent pulmonary epithelial cells promoted lung fibroblast transformation through secreting senescence-associated secretory phenotype (SASP) factors. Yap/Taz knockdown in mice lungs significantly decreased the expression of downstream profibrotic protein Ctgf and senescent markers p16 and p21, and alleviated PQ-induced pulmonary fibrosis. Interfering YAP/TAZ in senescent human pulmonary epithelial cells resulted in decreased expression of the anti-apoptosis protein survivin and elevated level of apoptosis. In conclusion, our findings reveal a novel mechanism by which the involvement of Hippo-YAP/TAZ activation in pulmonary epithelial cell senescence mediates the pathogenesis of PQ-induced pulmonary fibrosis, thereby offering novel insights and potential targets for the clinical management of PQ poisoning as well as providing the mechanistic insight of the involvement of Yap/Taz activation in cell senescence in pulmonary fibrosis and its related pulmonary disorders. The YIN YANG balance between cell senescence and apoptosis is important to maintain the homeostasis of the lung, the disruption of which will lead to disease.

Regulation of macrophage polarization and glucose metabolism by the ERK/MAPK-HK1 signaling pathway in paraquat-induced acute lung injury

Acute lung injury is the leading cause of paraquat (PQ) poisoning-related mortality. The mechanism by which macrophages are involved in PQ-induced acute lung injury remains unclear. In recent years, the role of metabolic reprogramming in macrophage functional transformation has received significant attention. The current study aimed to identify the role of altered macrophage glucose metabolism and molecular mechanisms in PQ poisoning-induced acute lung injury. We established a model of acute lung injury in PQ-intoxicated mice via the intraperitoneal injection of PQ. PQ exposure induces macrophage M1 polarization and promotes the release of inflammatory factors, which causes the development of acute lung injury in mice. In vitro analysis revealed that PQ altered glucose metabolism, which could be reversed by siRNA transfection to silence the expression of HK1, a key enzyme in glucose metabolism. RNA sequencing revealed that the ERK/MAPK pathway was the crucial molecular mechanism of PQ pathogenesis. Further, U0126, an ERK inhibitor, could inhibit PQ-induced HK1 activation and macrophage M1 polarization. These findings provide novel insights into the previously unrecognized mechanism of ERK/MAPK-HK1 activation in PQ poisoning.

An approach based on a combination of toxicological experiments and in silico predictions to investigate the adverse outcome pathway (AOP) of paraquat neuro-immunotoxicity

Paraquat (PQ) exposure is strongly associated with neurotoxicity. However, research on the neurotoxicity mechanisms of PQ varies in terms of endpoints of toxic assessment, resulting in a great challenge to understand the early neurotoxic effects of PQ. In this study, we developed an adverse outcome pathway (AOP) to investigate PQ-induced neuro-immunotoxicity from an immunological perspective, combining of traditional toxicology methods and computer simulations. In vivo, PQ can microstructurally lead to an early synaptic loss in the brain mice, which is a large degree regarded as a main reason for cognitive impairment to mice behavior. Both in vitro and in vivo demonstrated synapse loss is caused by excessive activation of the complement C1q/C3-CD11b pathway, which mediates microglial phagocytosis dysfunction. Additionally, the interaction between PQ and C1q was validated by molecular simulation docking. Our findings extend the AOP framework related to PQ neurotoxicity from a neuro-immunotoxic perspective, highlighting C1q activation as the initiating event for PQ-induced neuro-immunotoxicity. In addition, downstream complement cascades induce abnormal microglial phagocytosis, resulting in reduced synaptic density and subsequent non-motor dysfunction. These findings deepen our understanding of neurotoxicity and provide a theoretical basis for ecological risk assessment of PQ.

Cucurbit[8]uril-based supramolecular theranostics

Different from most of the conventional platforms with dissatisfactory theranostic capabilities, supramolecular nanotheranostic systems have unparalleled advantages via the artful combination of supramolecular chemistry and nanotechnology. Benefiting from the tunable stimuli-responsiveness and compatible hierarchical organization, host-guest interactions have developed into the most popular mainstay for constructing supramolecular nanoplatforms. Characterized by the strong and diverse complexation property, cucurbit[8]uril (CB[8]) shows great potential as important building blocks for supramolecular theranostic systems. In this review, we summarize the recent progress of CB[8]-based supramolecular theranostics regarding the design, manufacture and theranostic mechanism. Meanwhile, the current limitations and corresponding reasonable solutions as well as the potential future development are also discussed.

A highly sensitive and selective chemiluminescent probe for peroxynitrite detection in vitro, in vivo and in human liver cancer tissue

Peroxynitrite (ONOO-) is one of the important active nitrogen/reactive oxygen species that plays various roles in biological processes, such as inducing apoptosis and necrosis. Recent studies have shown that a significant increases in ONOO- content during tumor development, which is closely related to the level of oxidative stress within the tumor. It has been found that herbicide paraquat (PQ) can significantly increase the level of ONOO- in cells. Therefore, accurate monitoring abnormal changes in ONOO- caused by environmental hazardous materials and tumors is helpful in promoting the diagnosis and treatment of oxidative stress diseases (tumors), evenly environmental detection. Currently, traditional fluorescent probes for ONOO- detection have background interference. To address this, we developed a chemiluminescent probe (CL-1) and a fluorescent probe (Flu-1), using diphenyl phosphonate as a recognition group. CL-1 shows extremely sensitivity (9.8 nM), a high signal-to-noise(S/N) ratio (502), and excellent bioimaging capabilities compared to fluorescent probe (Flu-1). We have successfully used CL-1 to detect ONOO- produced by PQ stimulated cells, as well as endogenous ONOO- in tumor cells, mice, and human liver cancer tissues. Therefore, CL-1 can not only be a valuable tool for visualizing tumor and studying the role of ONOO- in tumor pathology, but the probe has the potential to be a powerful molecular imaging tool for exploring the complex biological role of ONOO- in a variety of biological Settings.

Protective effect of Bougainvillea glabra Choisy bract in toxicity induced by Paraquat in Drosophila melanogaster

Paraquat (PQ) is a herbicide widely used in agriculture to control weeds. The damage caused to health through intoxication requires studies to combating its damage to health. Bougainvillea glabra Choisy is a plant native to South America and its bracts contain a variety of compounds, including betalains and phenolic compounds, which have been underexplored about their potential applications and benefits for biological studies to neutralize toxicity. In this study, we evaluated the antioxidant and protective potential of the B. glabra bracts (BBGCE) hydroalcoholic extract against Paraquat-induced toxicity in Drosophila melanogaster. BBGCE demonstrated high antioxidant capacity in vitro through the assays of ferric-reducing antioxidant power (FRAP), radical 2,2-diphenyl-1-picrylhydrazyl (DPPH), free radical ABTS and quantification of phenolic compounds, confirmed through identifying the main compounds. Wild males of D. melanogaster were exposed to Paraquat (1.75 mM) and B. glabra Choisy (1, 10, 50 and 100 μg/mL) in agar medium for 4 days. Flies exposed to Paraquat showed a reduction in survival rate and a significant decrease in climbing capacity and balance test when compared to the control group. Exposure of the flies to Paraquat caused a reduction in acetylcholinesterase activity, an increase in lipid peroxidation and production of reactive species, and a change in the activity of the antioxidant enzymes. Co-exposure with BBGCE was able to block toxicity induced by PQ exposure. Our results demonstrate that bract extract has a protective effect against PQ on the head and body of flies, attenuating behavioral deficit, exerting antioxidant effects and blocking oxidative damage in D. melanogaster.

Reactive oxygen species impair Na+ transport and renal components of the renin-angiotensin-aldosterone system after paraquat poisoning

Paraquat (1,1'-dimethyl-4,4'-bipyridyl dichloride) is an herbicide widely used worldwide and officially banned in Brazil in 2020. Kidney lesions frequently occur, leading to acute kidney injury (AKI) due to exacerbated reactive O2 species (ROS) production. However, the consequences of ROS exposure on ionic transport and the regulator local renin-angiotensin-aldosterone system (RAAS) still need to be elucidated at a molecular level. This study evaluated how ROS acutely influences Na+-transporting ATPases and the renal RAAS. Adult male Wistar rats received paraquat (20 mg/kg; ip). After 24 h, we observed body weight loss and elevation of urinary flow and serum creatinine. In the renal cortex, paraquat increased ROS levels, NADPH oxidase and (Na++K+)ATPase activities, angiotensin II-type 1 receptors, tumor necrosis factor-α (TNF-α), and interleukin-6. In the medulla, paraquat increased ROS levels and NADPH oxidase activity but inhibited (Na++K+)ATPase. Paraquat induced opposite effects on the ouabain-resistant Na+-ATPase in the cortex (decrease) and medulla (increase). These alterations, except for increased serum creatinine and renal levels of TNF-α and interleukin-6, were prevented by 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (tempol; 1 mmol/L in drinking water), a stable antioxidant. In summary, after paraquat poisoning, ROS production culminated with impaired medullary function, urinary fluid loss, and disruption of Na+-transporting ATPases and angiotensin II signaling.

A hospital management algorithm for acute poisoning by Paraquat® in a pediatric population, a series of cases

Paraquat®, or N,N′-dimethyl-4,4′-bipyridinium dichloride, is a bipyridyl compound used as a non-selective herbicide and desiccant that can cause acute poisoning through all routes of exposure. There is no known antidote, and the available treatments are based on avoiding its absorption and timely removing it, in adults and children. We describe a case series of 14 pediatric patients from the department of Cauca, Colombia, with acute intoxication after oral intake of paraquat. Patients were referred to a medium-high complexity hospital in southwestern Colombia and treated according to an institutional protocol for acute paraquat poisoning. Acute paraquat poisoning after oral ingestion is associated with a high mortality rate, even with timely medical attention, as the compound has no known antidote and quickly reaches systemic concentrations for fulminant poisoning. Based on the available literature, our center has proposed a clinical protocol including early standard management, immunosuppressive and antioxidant treatments, and systemic removal techniques. This protocol suggests an adequate approach to acute paraquat poisoning in the pediatric population.

Exosomes from senescent epithelial cells activate pulmonary fibroblasts via the miR-217-5p/Sirt1 axis in paraquat-induced pulmonary fibrosis

BACKGROUND

Paraquat (PQ) is a widely used and highly toxic herbicide that poses a significant risk to human health. The main consequence of PQ poisoning is pulmonary fibrosis, which can result in respiratory failure and potentially death. Our research aims to uncover a crucial mechanism in which PQ poisoning induces senescence in epithelial cells, ultimately regulating the activation of pulmonary fibroblasts through the exosomal pathway.

METHODS

Cellular senescence was determined by immunohistochemistry and SA-β-Gal staining. The expression of miRNAs was measured by qPCR. Pulmonary fibroblasts treated with specific siRNA of SIRT1 or LV-SIRT1 were used to analysis senescent exosomes-mediated fibroblasts activation. Luciferase reporter assay and western blot were performed to elucidated the underlying molecular mechanisms. The effects of miR-217-5p antagomir on pulmonary fibrosis were assessed in PQ-poisoned mice models.

RESULTS

Impairing the secretion of exosomes effectively mitigates the harmful effects of senescent epithelial cells on pulmonary fibroblasts, offering protection against PQ-induced pulmonary fibrosis in mice. Additionally, we have identified a remarkable elevation of miR-217-5p expression in the exosomes of PQ-treated epithelial cells, which specifically contributes to fibroblasts activation via targeted inhibition of SIRT1, a protein involved in cellular stress response. Remarkably, suppression of miR-217-5p effectively impaired senescent epithelial cells-induced fibroblasts activation. Further investigation has revealed that miR-217-5p attenuated SIRT1 expression and subsequently resulted in enhanced acetylation of β-catenin and Wnt signaling activation.

CONCLUSION

These findings highlight a potential strategy for the treatment of pulmonary fibrosis induced by PQ poisoning. Disrupting the communication between senescent epithelial cells and pulmonary fibroblasts, particularly by targeting the miR-217-5p/SIRT1/β-catenin axis, may be able to alleviate the effects of PQ poisoning on the lungs.

Recent advances in the potential effects of natural products from traditional Chinese medicine against respiratory diseases targeting ferroptosis

Respiratory diseases, marked by structural changes in the airways and lung tissues, can lead to reduced respiratory function and, in severe cases, respiratory failure. The side effects of current treatments, such as hormone therapy, drugs, and radiotherapy, highlight the need for new therapeutic strategies. Traditional Chinese Medicine (TCM) offers a promising alternative, leveraging its ability to target multiple pathways and mechanisms. Active compounds from Chinese herbs and other natural sources exhibit anti-inflammatory, antioxidant, antitumor, and immunomodulatory effects, making them valuable in preventing and treating respiratory conditions. Ferroptosis, a unique form of programmed cell death (PCD) distinct from apoptosis, necrosis, and others, has emerged as a key area of interest. However, comprehensive reviews on how natural products influence ferroptosis in respiratory diseases are lacking. This review will explore the therapeutic potential and mechanisms of natural products from TCM in modulating ferroptosis for respiratory diseases like acute lung injury (ALI), asthma, pulmonary fibrosis (PF), chronic obstructive pulmonary disease (COPD), lung ischemia-reperfusion injury (LIRI), pulmonary hypertension (PH), and lung cancer, aiming to provide new insights for research and clinical application in TCM for respiratory health.

Improvement of inhaled paraquat induced lung and systemic inflammation, oxidative stress and memory changes by safranal

The effects of safranal and pioglitazone alone and their combination on inhaled paraquat (PQ)-induced systemic oxidative stress and inflammation as well as behavioral changes were examined in rats. In this study, animals were exposed to saline (Ctrl) or PQ (PQ groups) aerosols. PQ exposed animals were treated with dexamethasone, 0.8 and 3.2 mg/kg/day safranal (Saf-L and Saf-H), 5 mg/kg/day pioglitazone (Pio), and Saf-L + Pio for 16 days during PQ exposure period. PQ group showed increased numbers of total and differential WBCs in blood and bronchoalveolar lavage fluid (BALF), increased malondialdehyde (MDA), in the serum BALF and brain reduced thiol, catalase (CAT), and superoxide dismutase (SOD) levels compared to the control group (for all, p < 0.001). The escape latency and traveled distance were enhanced, but the time spent in the target quadrant in the probe day and the latency to enter the dark room 3, 24, 48, and 72 h after receiving an electrical shock, (in the shuttle box test) were decreased in the PQ group (p < 0.05 to P < 0.001). In all treated groups, all measure values were improved compared to PQ group (p < 0.05 to p < 0.001). In combination treated group of Saf-L + Pio, most measured values were more improved than the Saf-L and Pio groups (p < 0.05 to p < 0.001). Saf and Pio improved PQ-induced changes similar to dexamethasone but the effects produced by combination treatments of Saf-L + Pio were more prominent than Pio and Saf-L alone, suggesting a potentiating effect for the combination of the two agents.

Pesticides: An alarming detrimental to health and environment

Pesticides are chemical substances of natural or synthetic origin that are used to eradicate pests and insects. These are indispensable in the agricultural processes for better crop production. Pesticide use aims to promote crop yield and protect the crops from diseases and damage. Pesticides must be handled carefully and disposed of appropriately because they are dangerous to people and other species by default. Environmental pollution occurs when pesticide contamination spreads away from the intended plants. Older pesticides such as lindane and dichlorodiphenyltrichloroethane (DDT) may remain in water and soil for a longer time. These accumulate in various parts of the food chain and cause damage to the ecosystem. Biological techniques in the management of pest control such as importation, augmentation, and conservation, and the accompanying procedures are more efficient, less expensive, and ecologically sound than other ways. This review mainly focuses on the consequences on the targeted and non-targeted organisms including the health and well-being of humans by the use of pesticides and their toxicity. The side effects that occur when a pesticide's LD50 exceeds the accepted limit through oral or skin penetration due to their binding to various receptors such as estrogen receptors, GABA, EGFR, and others. These pesticide classes include carbamates, pyrethroids, organochlorides, organophosphorus, and others. The current study seeks to highlight the urgent requirement for a novel agricultural concept that includes a major reduction in the use of chemical pesticides.

A Forensic Case of Suicide Ingestion of Paraquat Herbicide: New Histological Insights and Revision of the Literature

ABSTRACT

Paraquat (PQ) is one of the most widely used herbicides in the world, and poisoning is generally associated with accidental, suicidal, or homicidal events. Therefore, in the forensic context, PQ could be in various ways involved as a possible cause of death of a subject. However, even though its systemic toxicity is known, the biological effects exerted on individual viscera have been explored only to some extent, especially in case of victim's survival. Therefore, a case concerning a suicidal ingestion of PQ with survival of 3 days was deemed of interest. Clinical toxicological analyses confirmed acute PQ intoxication, and after the death of the victim, an autopsy was performed showing local and systemic signs of ingestion of a caustic substance. Histologic examination revealed marked cellular damage to the major viscera, particularly the gastroesophageal tract, liver, kidneys, and lungs, with initial alveolar fibrosis noted despite the patient's short survival. This finding represents a new element in the context of PQ lung injury, as it has not been previously documented in the literature. Thus, histological findings in lethal intoxications after survival can reveal specific peculiarities still unknown and, therefore, assume transversal relevance not only at forensic but also clinical level.

Inhaled paraquat-induced lung injury in rat, improved by the extract of Zataria multiflora boiss and PPARγ agonist, pioglitazone

The effects of a PPAR-γ agonist, pioglitazone and Zataria multiflora (Z. multiflora) on inhaled paraquat (PQ)-induced lung oxidative stress, inflammation, pathological changes and tracheal responsiveness were examined. The study was carried out in control rats exposed to normal aerosol of saline, PQl and PQh groups exposed to aerosols of 27 and 54 mg/m3 PQ, groups exposed to high PQ concentration (PQh) and treated with 200 and 800 mg/kg/day Z. multiflora, 5 and 10 mg/kg/day pioglitazone, low doses of Z. multiflora + pioglitazone, and 0.03 mg/kg/day dexamethasone. Increased tracheal responsiveness, transforming growth factor beta (TGF-ß) and lung pathological changes due to PQh were significantly improved by high doses of Z. multiflora and pioglitazone, dexamethasone and extract + pioglitazone, (p < 0.05 to p < 0.001). In group treated with low doses of the extract + pioglitazone, the improvements of most measured variables were significantly higher than the low dose of two agents alone (p < 0.05 to p < 0.001). Z. multiflora improved lung injury induced by inhaled PQ similar to dexamethasone and pioglitazone which could be mediated by PPAR-γ receptor.

Integrated analysis of ceRNA-miRNA changes in paraquat-induced pulmonary epithelial-mesenchymal transition via high-throughput sequencing

Recent studies have shown that epithelial-mesenchymal transition (EMT) plays an important role in paraquat (PQ)-induced tissue fibrosis, which is the main cause of death in patients with PQ poisoning. However, no effective treatment for pulmonary interstitial fibrosis caused by PQ poisoning exists. It is of great significance for us to find new therapeutic targets through bioinformatics in PQ-induced EMT. We conducted transcriptome sequencing to determine the expression profiles of 1210 messenger RNAs (mRNAs), 558 long noncoding RNAs, 28 microRNAs (miRNAs), including 18 known-miRNAs, 10 novel-miRNAs and 154 circular RNAs in the PQ-exposed EMT group mice. Using gene ontology and Kyoto Encyclopaedia of Genes and Genomes analyses, we identified the pathways associated with signal transduction, cancers, endocrine systems and immune systems were involved in PQ-induced EMT. Furthermore, we constructed long noncoding RNA-miRNA-mRNA interrelated networks and found that upregulated genes included Il22ra2, Mdm4, Slc35e2 and Angptl4, and downregulated genes included RGS2, Gabpb2, Acvr1, Prkd3, Sp100, Tlr12, Syt15 and Camk2d. Thirteen new potential competitive endogenous RNA targets were also identified for further treatment of PQ-induced pulmonary tissue fibrosis. Through further study of the pathway and networks, we may identify new molecular targets in PQ-induced pulmonary EMT.

Mitochondrial reactive oxygen species initiate gasdermin D-mediated pyroptosis and contribute to paraquat-induced nephrotoxicity

Paraquat (PQ)-induced acute kidney injury (AKI) progresses rapidly and is associated with high mortality rates; however, no specific antidote for PQ has been identified. Poor understanding of toxicological mechanisms underlying PQ has hindered the development of suitable treatments to combat PQ exposure. Gasdermin D (GSDMD), a key executor of pyroptosis, has recently been shown to enhance nephrotoxicity in drug-induced AKI. To explore the role of pyroptosis in PQ-induced AKI, the plasma membrane damage of the cells was detected by LDH release assay. Western blot was performed to detect the cleavage of GSDMD. RNA sequencing analysis was performed to explore the mechanism of PQ induced nephrotoxicity. Herein, we demonstrated that PQ could induce pyroptosis in HK-2 cells and nephridial tissues. Mechanistically, PQ initiated GSDMD cleavage, and GSDMD knockout attenuated PQ-induced nephrotoxicity in vivo. Further analysis revealed that the accumulation of mitochondrial reactive oxygen species (ROS) induced p38 activation, contributing to PQ-induced pyroptosis. Furthermore, mitoquinone, a mitochondria-targeted antioxidant, reduced mitochondrial ROS levels and inhibited pyroptosis. Collectively, these findings provide insights into the role of GSDMD-dependent pyroptosis as a novel mechanism of PQ-induced AKI.

Regulation of NCOA4-mediated iron recycling ameliorates paraquat-induced lung injury by inhibiting ferroptosis

Paraquat (PQ) is an irreplaceable insecticide in many countries for the advantage of fast-acting and broad-spectrum. However, PQ was classified as the most prevailing poisoning substance for suicide with no specific antidote. Therefore, it is imperative to develop more effective therapeutic agents for the treatment of PQ poisoning. In the present study, both the RNA-Seq and the application of various cell death inhibitors reflected that ferroptosis exerts a crucial regulatory role in PQ poisoning. Moreover, we found PQ strengthens lipid peroxidation as evidenced by different experimental approaches. Of note, pretreatment of iron chelation agent DFO could ameliorate the ferroptotic cell death and alleviate the ferroptosis-related events. Mechanistically, PQ treatment intensively impaired mitochondrial homeostasis, enhanced phosphorylation of AMPK, accelerated the autophagy flux and triggered the activation of Nuclear receptor coactivator 4-ferritin heavy chain (NCOA4-FTH) axis. Importantly, the activation of autophagy was observed prior to the degradation of ferritin, and inhibition of autophagy could inhibit the accumulation of iron caused by the ferritinophagy process. Genetic and pharmacological inhibition of ferritinophagy could alleviate the lethal oxidative events, and rescue the ferroptotic cell death. Excitingly, in the mouse models of PQ poisoning, both the administration of DFO and adeno-associated virus-mediated FTH overexpression significantly reduced PQ-induced ferroptosis and improved the pathological characteristics of pulmonary fibrosis. In summary, the current work provides an in-depth study on the mechanism of PQ intoxication, describes a framework for the further understanding of ferroptosis in PQ-associated biological processes, and demonstrates modulation of iron metabolism may act as a promising therapeutic agent for the management of PQ toxicity.

Spatiotemporal Visualization of Paraquat Distribution, Toxicokinetics, and Its Detoxification in Zebrafish Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry Imaging

Paraquat is a highly toxic quaternary ammonium herbicide. It can damage the functions of multiple organs and cause irreversible pulmonary fibrosis in the human body. However, the toxicological mechanism of paraquat is not yet fully understood, and due to the lack of specific antidotes, the clinical treatment of paraquat intoxication is still a great medical challenge. In-depth research on its toxicity mechanism, toxicokinetics, and effective antidotes is urgently demanded. A new molecular imaging technique, matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), can simultaneously achieve quantitative and spatial analysis and offer an alternative, distinct, and useful technique for paraquat intoxication and consequent detoxication. Here, we visualized the spatial-temporal distribution and conducted toxicokinetic research on paraquat in zebrafish by using stable isotope-labeled internal-standard-aided MALDI-MSI for the first time. The results indicated that paraquat had a fast absorption rate and was widely distributed in different organs, such as the brain, gills, kidneys, and liver in zebrafish. Its half-life was long, and the elimination rate was slow. Paraquat reached its peak at 30 min and was mainly distributed in kidneys and intestines and then showed a tendency of declining first but mildly rising later at 6 h, accompanied by a wide distribution in kidneys and intestines again. It suggested that entero-systemic recirculation might lead to the observed secondary peaks, and perhaps it extended the residence time of paraquat in the body. In addition, we validated the potential detoxification effect of sodium salicylate as a potential antidote for paraquat from both the dimensions of distribution and quantification. In conclusion, MALDI-MSI conveniently provided the distinct and quantitative spatial-temporal distribution information on paraquat in the whole body of zebrafish; it will promote the understanding of its toxicokinetic characteristics and provide more valuable information for clinical treatment.

Curative effects of tectochrysin on paraquat-instigated testicular toxicity in rats: A biochemical and histopathological based study

Background

Paraquat (PQ) is a herbicide that is used globally in the agriculture sector to eradicate unwanted weeds, however it also induces significant damages in various organs of the body such as testes. Tectochrysin (TEC) is an important flavonoid that shows versatile therapeutic potentials. Currently, there is no established antidote to cure PQ-induced testicular toxicity.

Objective

The present study was conducted to evaluate the ameliorative effects of TEC against PQ prompted testicular damage.

Methods

Sprague-Dawley rats (n = 48) were used to conduct the trial. Rats were allocated in to 4 groups i.e., Control, PQ administrated group (5 mgkg-1), PQ + TEC co-administrated group (5 mgkg-1 + 2.5 mgkg-1) and TEC only administrated group (2.5 mgkg-1). The trial was conducted for 8 weeks. The activity of anti-oxidants and the levels of MDA and ROS were determined by spectrophotometric method. Steroidogenic enzymes as well as apoptotic markers expressions were evaluated by qRT-PCR. The level of hormones and inflammatory indices was quantified by enzyme-linked immunosorbent assay.

Results

PQ exposure markedly (P < 0.05) disturbed the biochemical, spermatogenic and histological profile in the rats. Nevertheless, TEC treatment considerably (P < 0.05) increased CAT, GPx GSR and SOD activity, besides decreasing MDA and ROS contents. TEC administration also increased sperm viability, count and motility. 17β-HSD, 3β-HSD, StAR and Bcl-2 expressions were also increased following TEC administration. The supplementation of TEC substantially (P < 0.05) decreased Bax, Caspase-3 expression and the levels of inflammatory markers i.e., interleukin-1β (IL-1β), interleukin-6 (IL-6), nuclear factor kappa-B (NF-κB), tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2) activity. Additionally, the levels of plasma testosterone, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were increased following TEC supplementation. Furthermore, TEC supplementation considerably decreased sperm structural abnormalities and histomorphological damages of the testes. The mitigative role of TEC might be due to its anti-inflammatory, anti-apoptotic, androgenic and anti-oxidant potentials.

Conclusion

Taken together, it is concluded that TEC can be used as a potential candidate to treat testicular toxicity.

Agricultural paraquat dichloride use and Parkinson's disease in California's Central Valley

BACKGROUND

Paraquat dichloride is currently among the most widely used commercial herbicides in the USA. In the present study, we provide epidemiological assessment of ambient paraquat exposure and Parkinson's disease (PD) risk in a population-based study of PD in agricultural regions of Central California.

METHODS

Based on 829 PD patients and 824 community controls, we assessed associations between ambient paraquat dichloride exposure and PD. We estimated residential and workplace proximity to commercial agricultural applications in three California counties since 1974 using the CA pesticide use reporting (PUR) data and land use maps. We evaluated any, duration and average intensity [pounds (0.45 kilograms) per acre per year] of exposure for paraquat in four time windows.

RESULTS

Ambient paraquat exposure assessed at both residence and workplace was associated with PD, based on several different exposure measures. The PD patients both lived and worked near agricultural facilities applying greater amounts of the herbicide than community controls. For workplace proximity to commercial applications since 1974, working near paraquat applications every year in the window [odds ratio (OR) = 2.15, 95% confidence interval (CI) = 1.46, 3.19] and a higher average intensity of exposure [per 10 pounds (4.54 kilograms), OR = 2.08, 95% CI = 1.31, 3.38] were both associated with an increased odds of PD. Similar associations were observed for residential proximity (duration: OR = 1.91, 95% CI = 1.30, 2.83; average intensity: OR = 1.72, 95% CI = 0.99, 3.04). Risk estimates were comparable for men and women, and the strongest odds were observed for those diagnosed at ≤60 years of age.

CONCLUSION

This study provides further indication that paraquat dichloride exposure increases the risk of Parkinson's disease.

Exploring Metabolic and Gut Microbiome Responses to Paraquat Administration in Male Wistar Rats: Implications for Oxidative Stress

In this study, we examined the metabolic and gut microbiome responses to paraquat (PQ) in male Wistar rats, focusing on oxidative stress effects. Rats received a single intraperitoneal injection of PQ at 15 and 30 mg/kg, and various oxidative stress parameters (i.e., MDA, SOD, ROS, 8-isoprostanes) were assessed after three days. To explore the omic profile, GC-qTOF and UHPLC-qTOF were performed to assess the plasma metabolome; 1H-NMR was used to assess the urine metabolome; and shotgun metagenomics sequencing was performed to study the gut microbiome. Our results revealed reductions in body weight and tissue changes, particularly in the liver, were observed, suggesting a systemic effect of PQ. Elevated lipid peroxidation and reactive oxygen species levels in the liver and plasma indicated the induction of oxidative stress. Metabolic profiling revealed changes in the tricarboxylic acid cycle, accumulation of ketone body, and altered levels of key metabolites, such as 3-hydroxybutyric acid and serine, suggesting intricate links between energy metabolism and redox reactions. Plasma metabolomic analysis revealed alterations in mitochondrial metabolism, nicotinamide metabolism, and tryptophan degradation. The gut microbiome showed shifts, with higher PQ doses influencing microbial populations (e.g., Escherichia coli and Akkermansia muciniphila) and metagenomic functions (pyruvate metabolism, fermentation, nucleotide and amino acid biosynthesis). Overall, this study provides comprehensive insights into the complex interplay between PQ exposure, metabolic responses, and gut microbiome dynamics. These findings enhance our understanding of the mechanisms behind oxidative stress-induced metabolic alterations and underscore the connections between xenobiotic exposure, gut microbiota, and host metabolism.

Occult paraquat poisoning causing pneumomediastinum and organizing pneumonia

Pneumomediastinum is not an uncommon manifestation of lung toxicity in acute paraquat ingestion. The condition is almost invariably seen with other lung parenchymal abnormalities such as consolidations, ground-glass opacities and interlobular septal thickening. The diagnosis may be challenging in cases with no history of toxin exposure, presentation with a subacute illness and/or absence of typical local or systemic features of paraquat toxicity.

Ferulic acid grafted into β-cyclodextrin nanosponges ameliorates Paraquat-induced human MRC-5 fibroblast injury

Paraquat (PQ) is a commercially important and effective herbicide in the world. Nevertheless, it has higher toxicity causing acute organ damage and different complications, mainly in the lungs and kidneys. Ferulic acid (FA), 4-hydroxy-3-methoxycinnamic acid imposes multiple pharmacological impacts. No protective effect of FA on PQ poisoning-caused human embryonic lung fibroblast damage has not been reported. Despite their many beneficial effects, FA is characterized by poor water solubility, low bioavailability, and phytochemical instability. To solve the problem, β-cyclodextrin nanosponge (β-CD NSs) was utilized to increase the solubility of FA so that it was grafted into β-CD NSs to establish β-CD@FA NSs. The purpose of this work was to examine for the first time the protective effect of β-CD@FA NS on MRC-5 human lung cells damages induced by PQ poisoning. MTS assay was performed to investigate the viability of MRC-5 cells at different concentrations of FA/β-CD@FA NSs when cells were co-cultured with 0.2 μg/mL PQ. The flow cytometry study was carried out to determine apoptosis. Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels were detected using appropriate biochemistry kits. Compared with the PQ group, the cell activity, CAT, and SOD levels were significantly increased in the FA and chiefly in β-CD@FA NSs intervention groups, whereas apoptosis and MDA levels were markedly decreased. The inflammatory factors tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and interleukin 22 (IL-22) were detected. The results demonstrate that β-CD@FA NSs can inhibit PQ-induced cell damage by enhancing antioxidant stress capacity and regulation of inflammatory responses.

Protective effects of natural compounds against paraquat-induced pulmonary toxicity: the role of the Nrf2/ARE signaling pathway

Paraquat (PQ) is a toxic herbicide to humans. Once absorbed, it accumulates in the lungs. PQ has been well documented that the generation of reactive oxygen species (ROS) is the main mechanism of its toxicity. Oxidative damage of PQ in lungs is represented as generation of cytotoxic and fibrotic mediators, interruption of epithelial and endothelial barriers, and inflammatory cell infiltration. No effective treatment for PQ toxicity is currently available. Several studies have shown that natural compounds (NCs) have the potential to alleviate PQ-induced pulmonary toxicity, due to their antioxidant and anti-inflammatory effects. NCs function as protective agents through stimulation of nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathways. Elevation of Nrf2 levels leads to the expression of its downstream enzymes such as SOD, CAT, and HO-1. The hypothesized role of the Nrf2/ARE signaling pathway as the protective mechanism of NCs against PQ-induced pulmonary toxicity is reviewed.

Smart, degradable, and eco-friendly carboxymethyl cellulose-CaII hydrogel-like networks gated MIL-101(FeIII) nanoherbicides for paraquat delivery

Nanopesticides have been selected as one of the top 10 chemical innovations for enhancing the efficacy and safety of agrochemicals. Herein, smart, degradable, and eco-friendly metal-organic framework MIL-101(FeIII) nanoherbicides coated with carboxymethyl cellulose-CaII (CMC-CaII) cross-linking hydrogel-like networks are synthesized via a simple strategy. The coating of the CMC-CaII hydrogel-like gatekeepers is oriented by the coordination unsaturated FeIII clusters on the surfaces of the MIL-101(FeIII) nanocarriers to form a dense film network to prevent paraquat (PQ) leakage. Based on the stimuli factors (acid/basic pH, GSH, phosphates, and EDTA) of physiological and natural environments of target plants, the nanoherbicides are combined with five stimuli-responsive properties to attain the various controlled release of packaged PQ by the disassembly of the gatekeepers and/or the degradation of the MOF skeleton structure. More importantly, based on the stimuli-responsive controlled release mechanisms, the eco-friendly nanocarriers are ultimately degraded against bioaccumulation in plants or soil. The coating of natural CMC could promote the spreading of PQ owing to improvement of wettability for aqueous droplets of nanoherbicides on hydrophobic foliage. The PQ trapped in nanocarriers can effectively prevent PQ degradation, which showed that cumulative degradation rate is ca. 2.6 times lower than that of technical PQ under UV irradiation. The prepared nanoherbicides loaded with PQ show good control efficacy against weeds by controlling the release of PQ; good safety on seed germination (germination rate 97.32-99.67 %), seedling emergence (emergence rate 95.53-99.67 %), and are beneficial for the growth of wheat seedling (increase rate of plant height 1.89-6.97 % and 0.54-5.67 % after 7 and 15 days of seedling emergence, respectively) in the greenhouse; good biosafety for honeybees (Apis mellifera L.), which shows that lethal rates were 2.04 and 2.55 times lower than technical PQ for incubation 24 and 48 h, respectively. The nanoherbicides have potential applications in the field for PQ green agriculture.

A mass event of paraquat poisoning via inhalation

Objective

In January 2023, a rare event of collective inhalation paraquat poisoning occurred in Shandong, China. To analyze the clinical characteristics of an event of respiratory tract paraquat poisoning through inhalation.

Methods

Clinical data from eight patients with paraquat inhalation poisoning were retrospectively analyzed.

Results

The patients were mainly exposed to paraquat via the respiratory tract. The main clinical manifestations were ocular and respiratory irritation. Lung computed tomography (CT) showed that all eight patients had varying degrees of lung injury, mainly manifesting as exudative lesions. Laboratory tests revealed arterial blood gas hypoxemia, abnormal white blood cell count, and increased neutrophil ratio. Sufficient glucocorticoid impact therapy was effective, and all eight patients survived.

Conclusion

Eight patients experienced chest tightness, shortness of breath, and varying degrees of lung injury due to inhalation of paraquat through the respiratory tract. The early use of glucocorticoids and other comprehensive treatment measures, active prevention and treatment of lung infections, and protection of organ function have beneficial effects in such cases.

Dienediamine: A safe surrogate for the herbicide paraquat

Paraquat (PQ) has been used as an herbicide worldwide because of its potent activity against weeds. However, it is highly toxic to humans. The very high fatality of PQ poisoning is due to its inherent toxicity and the lack of any effective treatment. Consequently, developing a non-toxic herbicide with comparable efficacy to PQ will contribute to global food security and help prevent PQ-related fatalities. Herein, we report a new herbicide called dienediamine, which was discovered from how to intervene the redox cycle of PQ, an inherent toxicity nature. Dienediamine, the "reduced" form of PQ with no function as an electron transfer agent, was shown to be non-toxic through comprehensive in vivo and in vitro experiments at molar concentrations equivalent to PQ's absolute lethal dose. Remarkably, dienediamine can undergo conversion to PQ under natural sunlight and ambient air conditions, exhibiting herbicidal activities that are comparable to those of PQ. The conversion of dienediamine to PQ, which is toxic to chloroplasts, is the key mechanism underlying its potent herbicidal activity. Our study discovers that dienediamine is a safe and superior alternative to PQ, possessing significant potential for application in sustainable agriculture globally.

Hemoadsorption and continuous venovenous hemodiafiltration in the management of paraquat poisoning during pregnancy: A case report

We describe the case of a mother in the second trimester of pregnancy with severe paraquat poisoning who ended her pregnancy at term and a healthy newborn. Management was initiated after 34 h of paraquat administration with the HA-230 hemoadsorption cartridge, followed by continuous venovenous hemodiafiltration for 120 h, in addition to cyclophosphamide and methylprednisolone. There was no evidence of adverse effects associated with treatment or extracorporeal therapy, and maternal and fetal well-being was maintained during the 26 days of hospitalization and at the end of pregnancy. This case treated with hemoadsorption and hemodiafiltration for paraquat poisoning during pregnancy is one of the few procedures reported in the literature and can be used as a guide for the management of subsequent cases.

Paraquat induced acute kidney and lung injury with a dramatic response to methylprednisolone: A case report

Background

Paraquat poisoning is one of the leading causes of fatal poisoning in many parts of the world, especially in agricultural countries. Its high toxicity even in small amounts causes rapid damage to multiple organs, especially the kidneys, lungs, and liver, mainly through free radical-mediated injury. As no specific antidote is yet available, early diagnosis and the importance of supportive therapy are critical parts of management. Some evidence suggests a survival benefit from using immunosuppressive drugs.

Case report

This case presentation concerns a 15-year-old boy from a village with a history of herbicide poisoning, later confirmed to be paraquat. Despite supportive therapy her condition continued to deteriorate with features of kidney and lung damage. The patient was then treated with methylprednisolone 500 mg daily for 5 days, along with other supportive care, and has made a remarkable recovery.

Conclusions

High efficacy as an herbicide, availability and low cost make paraquat an easy-to-encounter poison for suicidal or accidental use. Its high fatality calls for urgent and effective strategies to save lives. Methylprednisolone may play a role in its treatment.

Effect of WISP1 on paraquat-induced EMT

BACKGROUND

Paraquat (PQ) can induce pulmonary fibrosis (PF) by modulating epithelial-mesenchymal transition (EMT) of alveolar epithelial cells, but the molecular mechanism is unknown. In this paper, the role of Wnt-inducible signaling protein-1 (WISP1) in PQ-induced EMT was inspected.

METHODS

The morphology, apoptosis, and mortality of A549 cells were observed through a microscope. The mRNA and protein levels of WISP1, E-cadherin, and Vimentin were confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot.

RESULTS

With the increase of PQ concentration, the morphology of A549 cells was apparently changed, cell apoptosis and mortality were enhanced. Besides, the E-cadherin abundance was reduced (p < 0.01), however, WISP1 and Vimentin contents were boosted after PQ treatment (p < 0.01). With the increase of PQ treatment time, the epithelial index of cells first increased and then decreased. The expression of WISP1 gene increased significantly with the increase of PQ treatment time (p < 0.01). Silence of WISP1 abolished the effect of PQ treatment on E-cadherin and Vimentin levels (p < 0.01). Downregulation of WISP1 curbed morphology change and PQ-induced EMT in A549 cells.

CONCLUSION

Knockdown of WISP1 inhibited PQ-induced EMT in A549 cells. This conclusion might provide a new therapeutic target for PQ poisoning treatment.

Anti-inflammatory effect of dental pulp stem cells

Dental pulp stem cells (DPSCs) have received a lot of attention as a regenerative medicine tool with strong immunomodulatory capabilities. The excessive inflammatory response involves a variety of immune cells, cytokines, and has a considerable impact on tissue regeneration. The use of DPSCs for controlling inflammation for the purpose of treating inflammation-related diseases and autoimmune disorders such as supraspinal nerve inflammation, inflammation of the pulmonary airways, systemic lupus erythematosus, and diabetes mellitus is likely to be safer and more regenerative than traditional medicines. The mechanism of the anti-inflammatory and immunomodulatory effects of DPSCs is relatively complex, and it may be that they themselves or some of the substances they secrete regulate a variety of immune cells through inflammatory immune-related signaling pathways. Most of the current studies are still at the laboratory cellular level and animal model level, and it is believed that through the efforts of more researchers, DPSCs/SHED are expected to be transformed into excellent drugs for the clinical treatment of related diseases.

Ultrasensitive quantitation of Paraquat based on a small molecule-induced dual-cycle amplification strategy

Paraquat (PQ) is a typical biotoxic small molecule. Knowledge of how to directly introduce it into cyclic amplification rather than transform it into a secondary target is lacking in current analytical methods. Considering the urgent need for trace pesticide residue detection and the inherent defects of small molecule analysis, a CRISPR/Cas12a-driven small molecule-induced dual-cycle strategy was developed based on the immune competition method. The key to signal amplification is the mutual activation and acceleration between Cycle 1 triggered by the small molecule and Cycle 2 driven by CRISPR/Cas12a. Impressively, small molecules have been successfully incorporated into the dual-cycle strategy, which achieves a low detection limit (3.1 pg/mL) and a wide linear range (from 10 pg/mL to 50 μg/mL). Moreover, the designed biosensor was successfully employed to evaluate the PQ residual level in real samples and showed effective implementation for the bioanalysis of small molecule targets and pesticide residue-related food safety.

Abnormalities of serum lipid metabolism in patients with acute paraquat poisoning caused by ferroptosis

As the mechanism of paraquat (PQ) poisoning is still not fully elucidated, and no specific treatment has been developed in medical practice, the management of PQ poisoning continues to present a medical challenge. In this study, the objective was to investigate the early metabolic changes in serum metabolism and identify the key metabolic pathways involved in patients with PQ poisoning. Quantitative analysis was conducted to determine the relevant metabolites. Additionally, experiments were carried out in both plasma and cell to elucidate the mechanisms underlying metabolic disorder and cell death in PQ poisoning. The study found that polyunsaturated fatty acids (PUFAs) and their metabolites, such as arachidonic acid (AA) and hydroxy eicosatetraenoic acids (HETEs), were significantly increased by non-enzymatic oxidative reaction. Reactive oxygen species (ROS) production increased rapidly at 2 h after PQ poisoning, followed by an increase in PUFAs at 12 h, and intracellular glutathione, cysteine (Cys), and Fe2+ at 24 h. However, at 36 h later, intracellular glutathione and Cys decreased, HETEs increased, and the expression of SLC7A11 and glutathione peroxidase 4 (GPX4) decreased. Ultrastructural examination revealed the absence of mitochondrial cristae. Deferoxamine was found to alleviate lipid oxidation, and increase the viability of PQ toxic cells in the low dose. In conclusion, unsaturated fatty acids metabolism was the key metabolic pathways in PQ poisoning. PQ caused cell death through the induction of ferroptosis. Inhibition of ferroptosis could be a novel strategy for the treatment of PQ poisoning.

Ecotoxicology of the herbicide paraquat: effects on wildlife and knowledge gaps

Paraquat (PQ) is an organic herbicide introduced to the commercial market in 1962 and since linked to a variety of human health effects, including lung fibrosis, liver tumors, and Parkinson's disease. Although PQ is banned in the European Union, it is still frequently used in agricultural areas of the United States and Asia. The general mechanism of PQ's toxicity is the disruption of the redox cycle in cells. This mini-review summarizes our current understanding of PQ toxicity in non-target plants and animals. Among vertebrates, PQ sensitivity tends follow the pattern of fish > amphibians > mammals > birds. Aquatic plants are particularly vulnerable to PQ, with EC50 values ranging from ~28-280 μg/L. A number of convenient but non-specific biomarkers have been identified for non-target species, including the activities of antioxidant enzymes such as superoxide dismutase and catalase, histological changes in the gill structures of fish, and the upregulation of genes associated with the cytochrome p450 monooxygenase system. Significant literature gaps include a lack of data for environmentally realistic conditions (i.e., chronic, low concentration, multi-stressor), toxicity in reptiles, and population- and ecosystem-level effects. Although PQ is a useful herbicide, considering the many human and ecological health impacts, it may be time for regulators and the agricultural industry to reconsider its use.

The novel peptide DR4penA attenuates the bleomycin- and paraquat-induced pulmonary fibrosis by suppressing the TGF-β/Smad signaling pathway

Pulmonary fibrosis (PF), which is caused by continuous alveolar epithelial cell injury and abnormal repair, is referred to as a difficult disease of the lung system by the World Health Organization due to its rapid progression, poor prognosis, and high mortality rate. However, there is still a lack of ideal therapeutic strategies. The peptide DR8 (DHNNPQIR-NH2 ), which is derived from rapeseed, exerted antifibrotic activity in the lung, liver, and kidney in our previous studies. By studying the structure-activity relationship and rational design, we introduced an unnatural hydrophobic amino acid (α-(4-pentenyl)-Ala) into DR8 and screened the novel peptide DR4penA (DHNα-(4-pentenyl)-APQIR-NH2 ), which had higher anti-PF activity, higher antioxidant activity and a longer half-life than DR8. Notably, DR4penA attenuated bleomycin- and paraquat-induced PF, and the anti-PF activity of DR4penA was equivalent to that of pirfenidone. Additionally, DR4penA suppressed the TGF-β/Smad pathway in TGF-β1-induced A549 cells and paraquat-induced rats. This study demonstrates that the novel peptide DR4penA is a potential candidate compound for PF therapy, and its antifibrotic activity in different preclinical models of PF provides a theoretical basis for further study.

Predicting mortality in paraquat poisoning through clinical findings, with a focus on pulmonary and cardiovascular system disorders

BACKGROUND

Paraquat, one of the most widely used herbicides, poses a significant risk of mortality through self-poisoning and subsequent multiple organ failure. The primary objective aimed to identify the factors associated with death in patients poisoned by paraquat.

METHODS

A cross-sectional retrospective review was conducted at a tertiary referral hospital over five years. Eligible patients presented with acute paraquat toxicity between 1 January 2016 and 31 December 2020. Medical records of 148 patients were reviewed.

RESULTS

The in-hospital fatality rate was found to be 21.8%. Multivariate analysis revealed that the amount of paraquat ingested and clinical presentations, particularly pulmonary and cardiovascular system disorders, were significantly associated with mortality.

CONCLUSION

Our study highlights that the amount of paraquat ingested, along with the presence of pulmonary and cardiovascular system disorders, can serve as prognostic indicators for mortality rates in cases of paraquat poisoning. These findings have important implications for physicians in predicting the prognosis and mortality of paraquat poisoning patients.

Predicting acute paraquat toxicity using physiologically based kinetic modelling incorporating in vitro active renal excretion via the OCT2 transporter

Including active renal excretion in physiologically based kinetic (PBK) models can improve their use in quantitative in vitro- in vivo extrapolation (QIVIVE) as a new approach methodology (NAM) for predicting the acute toxicity of organic cation transporter 2 (OCT2) substrates like paraquat (PQ). To realise this NAM, kinetic parameters Vmax and Km for in vitro OCT2 transport of PQ were obtained from the literature. Appropriate scaling factors were applied to translate the in vitro Vmax to an in vivo Vmax. in vitro cytotoxicity data were defined in the rat RLE-6TN and L2 cell lines and the human A549 cell line. The developed PQ PBK model was used to apply reverse dosimetry for QIVIVE translating the in vitro cytotoxicity concentration-response curves to predicted in vivo toxicity dose-response curves after which the lower and upper bound benchmark dose (BMD) for 50% lethality (BMDL50 and BMDU50) were derived by applying BMD analysis. Comparing the predictions to the in vivo reported LD50 values resulted in a conservative prediction for rat and a comparable prediction for human showing proof of principle on the inclusion of active renal excretion and prediction of PQ acute toxicity for the developed NAM.

Paraquat-induced ferroptosis suppression via NRF2 expression regulation

Paraquat (PQ) is an environmentally friendly and efficient herbicide, but PQ misuse or intentional self-use can cause death through multiple organ damage and can cause acute lung injury. Existing clinical treatments alleviate symptoms but do not significantly improve the mortality rate. Ferroptosis is a type of necrosis that presents in a manner very similar to the cell damage induced by high doses of PQ, but the role of ferroptosis in paraquat-induced lung injury remains unclear. In this study, we aimed to explore the role of ferroptosis in PQ-induced A549 cell injury and identify the potential mechanisms and critical sites of protection against PQ-induced A549 injury by ferroptosis inhibitors. We found that the ferroptosis inhibitors Ferr-1 and Lip-1 inhibit ferroptosis by attenuating oxidative stress through the upregulation of NRF2 gene expression. The protective role of the ferroptosis inhibitor Dfo was most evident in paraquat-induced cell injury. Dfo inhibited ferroptosis by iron chelation and promoted NRF2 protein level reduction. NRF2 attenuated PQ-induced ferroptosis in A549 cells, mainly through the upregulation of SLC40A1 to encourage the movement of iron to the extracellular side to alleviate iron overload, and the upregulation of SLC7A11 to promote the expression of GPX4 to inhibit lipid peroxidation.

Regulation of lung inflammation by adiponectin

Adiponectin is an insulin sensitizing hormone that also plays a role in the regulation of inflammation. Although adiponectin can exert pro-inflammatory effects, more studies have reported anti-inflammatory effects, even in non-adipose tissues such as the lung. Obesity is considered an inflammatory disease, is a risk factor for lung diseases, and is associated with decreased levels of plasma adiponectin. The results of recent studies have suggested that adiponectin exerts anti-inflammatory activity in chronic obstructive pulmonary disease, asthma and invasive fungal infection. The signaling receptors of adiponectin, AdipoR1 and AdipoR2, are expressed by epithelial cells, endothelial cells, and immune cells in the lung. In this mini-review, we discuss the anti-inflammatory mechanisms of adiponectin in lung cells and tissues.

Assessment of pulmonary fibrosis induced by paraquat using Al18F-NODA-FAPI-04 PET/CT

The lack of a highly sensitive method to evaluate paraquat (PQ)-induced pulmonary fibrosis and predict disease progression remains an unresolved clinic issue. Fibroblast activation protein (FAP) may play an important role in the pathogenesis of PQ-induced pulmonary fibrosis. We aimed to evaluate the role of FAP in the PQ-induced pulmonary fibrosis and the utility of fibroblast activation protein inhibitor (FAPI) for positron emission tomography (PET) imaging in PQ-induced pulmonary fibrosis. In our study, two cases of PQ poisoning were presented and FAPI PET/CT was performed as a novel imaging technique. The uptake of FAPI increased in both cases of PQ poisoning. Animal experiments were then performed to validate the findings in the patients. Physiological FAPI lung uptake was higher in mice of the PQ group than in the control group. The results of histological analysis and Western blot were consistent with the findings of PET/CT imaging. The pulmonary fibrosis animal model was developed by intragastric gavage of PQ. PET/CT imaging was performed after injection of FAPI. Lung tissues of mice were collected for fibrosis assessment after imaging. Immunohistochemistry for FAP, histology and Western blot for collagen were performed to further validate the imaging findings. In conclusion, FAPI was involved in the pathogenesis of fibrosis induced by PQ, and PET/CT with FAPI could detect lung fibrogenesis, making it a promising tool to assess early disease activity and predict disease progression.

Biodegradation Capabilities of Paraquat-Degrading Bacteria Immobilized on Nanoceramics

The biodegradation of paraquat was investigated using immobilized microbial cells on nanoceramics fabricated from nanoscale kaolinite. Pseudomonas putida and Bacillus subtilis, which degrade paraquat, were immobilized separately on nanoceramics (respectively called IC_nc-P and IC_nc-B). The attachment of bacteria to nanoceramics resulted from electrostatic force interactions, hydrogen bonding, and covalent bonding (between the cells and the support materials). The initial 10 mg L^-1 concentration of paraquat in water was removed by the adsorption process using nanoceramics at 68% and ceramics at 52%, respectively. The immobilized cells on the nanoceramics were able to remove approximately 92% of the paraquat within 10 h, whereas the free cells could only remove 4%. When the paraquat was removed, the cell-immobilized nanoceramics exhibited a significant decrease in dissolved organic nitrogen (DON). IC_nc-B was responsible for 34% of DON biodegradation, while IC_nc-P was responsible for 22%. Ammonia was identified as the end product of ammonification resulting from paraquat mineralization.

Case report: Lung transplantation for treatment of paraquat intoxication: timing of transplantation

Objective: To analyze the optimal timing of lung transplantation and summarize postoperative complications and their management after paraquat poisoning. Methods: Here, we present the clinical course of a 17-year-old boy with paraquat poisoning, in whom bilateral lung transplantation (LT) was performed. We reviewed the eight previously published articles relevant to LT after paraquat poisoning to summarize the therapeutic strategy. Results: A 17-year-old boy was admitted to the hospital after ingestion of 30-50 mL 25% paraquat. Mechanical ventilation was initiated on the 25th day after intoxication. Venovenous extracorporeal membrane oxygenation was initiated on the 26th day. Sequential bilateral LT was performed on the 27th day. Several complex postoperative complications occurred and the patient was discharged on the 50th day postoperatively. Eight case reports were included in the literature review, including 11 patients with paraquat poisoning undergoing LT. Three patients died due to paraquat poisoning leading to fibrosis in the transplanted lungs or postoperative complications. Eight patients survived during follow-up. Conclusion: LT after herbicide poisoning should be planned when hepatorenal function starts to recover, and waiting for complete recovery is unnecessary. Prevention of infection before surgery is important to reduce the incidence of postoperative infection. Complex perioperative complications caused by the herbicide itself or the late timing of transplantation can be successfully managed by a multidisciplinary team.

Human amnion-derived mesenchymal stem cells attenuate acute lung injury in two different acute lung injury mice models

Acute lung injury (ALI) is one of the most common clinical emergencies with limited effective pharmaceutical treatment in the clinic, especially when it progresses to acute respiratory distress syndrome (ARDS). Currently, mesenchymal stem cells (MSCs) exhibit specific superiority for ALI/ARDS treatment. However, stem cells from different sources may result in controversial effects on similar disease conditions. This study aimed to determine the effects of human amnion-derived mesenchymal stem cells (hAMSCs) on two different ALI mice model. The administered hAMSCs effectively accumulated in the lung tissues in all hAMSC-treated groups. Compared with the model and 1% human serum albumin (HSA) groups, high-dose hAMSCs (1.0 × 10⁶ cells) group significantly alleviated alveolar-capillary permeability, oxidative stress, inflammatory factors level and histopathological damage. In addition, the NF-κB signaling pathway is one of the key pathways activated during lipopolysaccharide (LPS) or paraquat (PQ)-induced lung injury. Our results indicated that hAMSCs (1.0 × 10⁶ cells) obviously inhibited the expression of p-IKKα/β, p-IκBα, and p-p65 in the lung tissue (p < 0.05). The high-dose (HD) hAMSC treatment exerted beneficial therapeutic effects on ALI mice models without detectable adverse reactions. The therapeutic effect of hAMSCs might involve NF-κB signaling pathway inhibition. hAMSC treatment is a potential candidate therapy for ALI.

The significance of APACHE II as a predictor of mortality in paraquat poisoning: A systematic review and meta-analysis

The Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system is utilised as a prognostic method in paraquat poisoning; however, current evidence shows ambiguity. Although some studies have shown APACHE II to be a superior tool, others have reported it inferior to other prognostic markers, such as lactate, severity index of paraquat poisoning and urine paraquat concentration. Hence, to address this ambiguity, we conducted a systematic review and meta-analysis to analyse prognostic accuracy of APACHE II score in predicting mortality in paraquat poisoning. We included twenty studies with 2524 paraquat poisoned patients in the systematic review, after a comprehensive literature search in databases PubMed, Embase, Web of Science, Scopus and Cochrane Library, from which 16 studies were included in the meta-analysis. The survivors of paraquat poisoning were found to have significantly lower APACHE II scores (Mean Difference (MD): -5.76; 95% CI: -7.93 to -3.60 p < 0.0001; n = 16 studies) compared to non-survivors. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) for APACHE II score <9 was found to be 74%, 68%, 2.58, 0.38 and 7.10, respectively (n = 5 studies). The area under the curve (AUC) of the bivariate summary receiver operating characteristic (SROC) curve was found to be 0.80. The pooled sensitivity, specificity, PLR, NLR and DOR for APACHE II score ≥9 was found to be 73%, 86%, 4.69, 0.33 and 16.42, respectively (n = 9 studies). The AUC of the SROC curve was found to be 0.89. Pairwise AUC comparison of APACHE II with other prognostic markers showed serum presepsin to have a significantly better discriminatory ability than APACHE II. Through the findings of this study, we conclude that APACHE II was found to be a good indicator of death in paraquat poisoning patients. However, higher APACHE II scores (≥9) depicted greater specificity in predicting mortality in paraquat poisoning. Thus, APACHE II can be used as a practical tool in the hand of physicians to prognose patients with paraquat poisoning to aid clinical decisions.

Nitric oxide-mediated the therapeutic properties of induced pluripotent stem cell for paraquat-induced acute lung injury

The mortality rate associated with acute lung injury (ALI) and its severe form, acute respiratory distress syndrome, is high. Induced pluripotent stem cell (iPSC) therapy is a potential treatment method for ALI, but its therapeutic efficacy is limited in injured lungs. Nitric oxide (NO) has various physiological actions. The current study investigated the effect of iPSCs pretreated with NO donors in paraquat (PQ)-induced ALI mouse model. Male C57BL/6 mice were intraperitoneally injected with PQ, followed by infusion of phosphate-buffered saline, iPSCs, L-arginine pretreated iPSCs, or Nitro-L-arginine methylester (L-NAME) pretreated iPSCs through the tail veins. Histopathological changes, pulmonary microvascular permeability, and inflammatory cytokine levels were analyzed after 3 or 28 d. The effects on iPSC proliferation, migration, and adhesion were evaluated in vitro. More L-arginine-pretreated iPSCs were selectively trafficked into the injured pulmonary tissue of mice with LPS-induced ALI, drastically diminishing the histopathologic changes and inflammatory cytokine levels (IL-1β and IL-6). There was also markedly improved pulmonary microvascular permeability and pulmonary function. The NO inhibitor abolished the protective effects of iPSCs. In addition, the ability of L-arginine to promote the proliferation and migration of iPSCs was decreased by L-NAME pretreatment, suggesting that NO might mediate the therapeutic benefits of iPSC. The improvement of the iPSC physiological changes by the endogenous gaseous molecule NO reduces lung injury severity. L-Arginine represents a pharmacologically important strategy for enhancing the therapeutic potential of iPSCs.

Overhauling the ecotoxicological impact of synthetic pesticides using plants' natural products: a focus on Zanthoxylum metabolites

The reduction in agricultural production due to the negative impact of insects and weeds, as well as the health and economic burden associated with vector-borne diseases, has promoted the wide use of chemicals that control these "enemies." However, the use of these synthetic chemicals has been recognized to elicit negative impacts on the environment as well as the health and wellbeing of man. In this study, we presented an overview of recent updates on the environmental and health impacts of synthetic pesticides against agro-pest and disease vectors while exhaustive reviewing the potentials of natural plant products from Zanthoxylum species (Rutaceae) as sustainable alternatives. This study is expected to spur further research on exploiting these plants and their chemicals as safe and effective pesticide entities to minimize the impact of their chemical and synthetic counterparts on health and the environment.

Applications of a powerful model organism Caenorhabditis elegans to study the neurotoxicity induced by heavy metals and pesticides

The expansion of industry and the use of pesticides in agriculture represent one of the major causes of environmental contamination. Unfortunately, individuals and animals are exposed to these foreign and often toxic substances on a daily basis. Therefore, it is crucial to monitor the impact of such chemicals on human health. Several in vitro studies have addressed this issue, but it is difficult to explore the impact of these compounds on living organisms. A nematode Caenorhabditis elegans has become a useful alternative to animal models mainly because of its transparent body, fast growth, short life cycle, and easy cultivation. Furthermore, at the molecular level, there are significant similarities between humans and C. elegans. These unique features make it an excellent model to complement mammalian models in toxicology research. Heavy metals and pesticides, which are considered environmental contaminants, are known to have affected the locomotion, feeding behavior, brood size, growth, life span, and cell death of C. elegans. Today, there are increasing numbers of research articles dedicated to this topic, of which we summarized the most recent findings dedicated to the effect of heavy metals, heavy metal mixtures, and pesticides on the well-characterized nervous system of this nematode.