Increased 90-Day Mortality in Spontaneously Breathing Patients With Paraquat Poisoning: In Addition to Disease Severity, Lung Strain May Play a Role*

Association between toxicity-index of diquat and in-hospital mortality in patients with acute diquat poisoning: a retrospective cohort study

BackgroundThis study investigates the impact of diquat toxicity levels on in-hospital mortality rates among patients with acute diquat poisoning. It aims to clarify the relationship between diquat toxicity scores and the likelihood of death during hospitalization.MethodsA retrospective cohort study was conducted on 98 individuals with acute diquat poisoning. Data on post-ingestion time, initial diquat plasma concentration, and clinical outcomes were systematically collected for all participants. The toxicity-index of diquat was calculated based on post-ingestion time and initial diquat plasma concentration. Logistic regression analysis was utilized to assess the association between toxicity-index of diquat and in-hospital mortality rates, adjusting for potential confounding variables such as age, comorbidities, and treatment interventions.ResultsThe study found that the overall prevalence of in-hospital mortality was 34.7%, with 58.2% in males. The multivariable-adjusted regression coefficient for in-hospital mortality associated with the toxicity-index was 1.09, with a 95% confidence interval (CI) of 1.01-1.17. Subsequent exploratory subgroup analysis indicated that there were no significant interactions (all P values for interaction were >0.05).ConclusionsThe study found that higher diquat toxicity-index values correlate with increased in-hospital mortality in acute diquat poisoning cases, indicating that the toxicity-index could be a useful biomarker for assessing mortality risk.

Liver injury in paraquat poisoning: A retrospective cohort study

BACKGROUND AND AIMS

Liver injury is one of the common complications of paraquat (PQ) poisoning, but whether the degree of liver injury is related to patient prognosis is still controversial. This study aimed to investigate whether liver injury was a risk factor for death in PQ-poisoned patients.

METHODS

We conducted a retrospective cohort study of PQ-poisoned patients from the past 10 years (2011-2020) from a large tertiary academic medical centre in China. PQ-poisoned patients were divided into a normal liver function group (n = 580) and a liver injury group (n = 60). Propensity score matching (PSM) analysis was then performed.

RESULTS

A total of 640 patients with PQ poisoning were included in this study. To reduce the impact of bias, dose of PQ, urinary PQ concentration and time from poisoning to hospital admission were matched between the two groups. A 3:1 PSM analysis was performed, ultimately including 240 patients. Compared with the normal liver function group, patients in the liver injury group were older, had a higher R value ([ALT/ULN]/[ALP/ULN]) (p < .001) and had a higher mortality rate. Cox regression analysis showed that there was no significant association between alanine aminotransferase, alkaline phosphatase, total bilirubin levels and hazard of death, but age, PQ dose, creatine kinase isoenzyme, creatine kinase, white blood cell count, neutrophil percentage and lymphocyte percentage were associated with mortality in patients with PQ poisoning.

CONCLUSIONS

The occurrence of liver injury within 48 h after PQ poisoning was a risk factor for mortality, and such liver injury was likely of a hepatocellular nature. Age, PQ dose, creatine kinase isoenzyme and white blood cell count were positively correlated with mortality, while creatine kinase, percentage of neutrophils and lymphocytes were inversely correlated.

Roles of oxidative stress/JNK/ERK signals in paraquat-triggered hepatic apoptosis

Paraquat (PQ), a toxic and nonselective bipyridyl herbicide, is one of the most extensively used pesticides in agricultural countries. In addition to pneumotoxicity, the liver is an important target organ for PQ poisoning in humans. However, the mechanism of PQ in hepatotoxicity remains unclear. In this study, we found that exposure of rat hepatic H4IIE cells to PQ (0.1-2 mM) induced significant cytotoxicity and apoptosis, which was accompanied by mitochondria-dependent apoptotic signals, including loss of mitochondrial membrane potential (MMP), cytosolic cytochrome c release, and changes in the Bcl-2/Bax mRNA ratio. Moreover, PQ (0.5 mM) exposure markedly induced JNK and ERK1/2 activation, but not p38-MAPK. Blockade of JNK and ERK1/2 signaling by pretreatment with the specific pharmacological inhibitors SP600125 and PD98059, respectively, effectively prevented PQ-induced cytotoxicity, mitochondrial dysfunction, and apoptotic events. Additionally, PQ exposure stimulated significant oxidative stress-related signals, including reactive oxygen species (ROS) generation and intracellular glutathione (GSH) depletion, which could be reversed by the antioxidant N-Acetylcysteine (NAC). Buffering the oxidative stress response with NAC also effectively abrogated PQ-induced hepatotoxicity, MMP loss, apoptosis, and phosphorylation of JNK and ERK1/2 protein, however, the JNK or ERK inhibitors did not suppress ROS generation in PQ-treated cells. Collectively, these results demonstrate that PQ exposure induces hepatic cell toxicity and death via an oxidative stress-dependent JNK/ERK activation-mediated downstream mitochondria-regulated apoptotic pathway.

Prognostic Value of the Average Lung CT Number in Patients with Acute Paraquat Poisoning

Objective

The chest computed tomography (CT) examination is an important clinical examination in the diagnosis and monitoring of paraquat- (PQ-) induced lung injury. The aim of this study was to explore the prognostic value of the average lung CT number acquired by quantitative CT techniques in patients with acute paraquat poisoning in the early stages of the disease.

Methods

46 patients who suffered from acute PQ poisoning in the emergency department of the Nanjing Drum Tower Hospital from January 2015 to June 2020 were enrolled in the present study. The patients were divided into survival group (n = 21) and nonsurvival group (n = 25). Clinical data were collected from subjects who met the inclusion criteria, including general information, personal disease history, and laboratory test indicators. The average lung CT numbers of each patient were obtained by quantitative CT techniques. Receiver operating characteristic (ROC) analysis was conducted to assess the prognostic value of average lung CT number in patients with acute paraquat poisoning.

Results

The average CT numbers of the middle-lung, lower-lung, and whole lung fields in the nonsurvival group were significantly higher than those of the survival group (p < 0.0001). However, the upper-lung field was not significantly different between the two groups (p = 0.7765). The AUCs of different levels ranged from 0.554 to 0.977, among which the lower-lung field presented the largest AUC of 0.977 (95% CI: 0.943∼1; cut-off value: -702Hu; sensitivity 96%; specificity, 90.5%; YI: 0.865), followed by the whole lung field 0.914 (95% CI: 0.830∼0.999; cut-off value: -727Hu; sensitivity 76%; specificity, 95.2%; YI: 0.712) and the middle-lung field 0.87 (95% CI: 0.768∼0.971; cut-off value: -779Hu; sensitivity 80%; specificity, 85.7%; YI: 0.657).

Conclusion

The present study indicated that the average lung CT number could be used to evaluate the relationship between the severity of PQ-induced lung injury and prognosis, especially in the lower-lung field. However, further research is needed to draw a clear conclusion.

Phlebotomy-induced iron deficiency attenuates the pulmonary toxicity of paraquat in mice

Phlebotomy is an effective method in the prevention and treatment of some poisonings, among which iron deficiency is a well-known consequence. Given the role of iron in paraquat (PQ) toxicity, the present study investigated the effectiveness of phlebotomy in PQ pulmonary toxicity. After conducting preliminary studies, the duration time of phlebotomy was set to be seven days. Then, the mice were divided into nine separate groups. Groups 1-3 received a single dose of normal saline, and 5 and 10 mg/kg of PQ, respectively, and phlebotomy was not performed on them (NPG status). The animals in groups 4-6 first underwent phlebotomy for seven days and then received a single dose of normal saline, and 5 and 10 mg/kg of PQ (PBPT status). Groups 7-9 first received a single dose of normal saline, and 5 and 10 mg/kg of PQ and then underwent phlebotomy for seven days (PAPT status). Seven days after acute exposure to PQ, the animals were anesthetized and biochemical biomarkers as well as lung tissue changes were evaluated. The findings showed that phlebotomy before and after PQ toxicity significantly decreased serum iron compared to NPG condition. In the PBPT status, phlebotomy could prevent PQ toxicity by increasing the activity of catalase and superoxide dismutase (SOD) and decreasing the activity of myeloperoxidase (MPO), and the levels of hydroxyproline and lipid peroxidation in the lung tissue. In the PAPT status, a significant improvement was observed in SOD and MPO activities compared to the NPG status. Confirming the biochemical findings, the histological results indicated higher effectiveness of phlebotomy in preventing PQ toxicity (PBPT) compared to its therapeutic effects (PAPT). Considering the role of iron in PQ toxicity, it appears that the reduction of serum iron levels during phlebotomy can be effective in preventing lung injuries caused by PQ and improving the performance of the pulmonary antioxidant system.

High-resolution computed tomography (HRCT) analysis in anti-synthase antibody syndrome with organizing pneumonia

OBJECTIVE

The organizing pneumonia (OP) pattern is the second most common finding in anti-synthase antibody syndrome (ASS), and nonspecific interstitial pneumonia (NSIP) is the most common finding. This study analysed the OP score changes by semiquantitative and quantitative analysis methods and the correlation between the high-resolution computed tomography (HRCT) indexes and the pulmonary function test parameters (PFTs) in ASS patients.

METHODS

Data from ASS-OP patients admitted to the respiratory department of Ping Jin Hospital from October 2014 to June 2020 were retrospectively reviewed and analysed.

RESULTS

Fourteen ASS-OP patients were recruited for this study. (1) In method-1, the consolidation (CO) score and the mean lung attenuation (MA) of poorly aerated and fibrosis lung fields (MA_fibrosis) (r=0.56, P=0.04), the ground-glass opacity (GGO) score and the MA of non-aerated lung fields (MA_nonaerated) (r=-0.64, P=0.01), and the CO plus the GGO (CG) score and the MA_nonaerated (r=-0.59, P=0.03) of the lung fields had liner correlations. In method-2, the GGO score to the MA_nonaerated (r=-0.58, P=0.03), and the CG (r=-0.68, P=0.01) score to the MA_nonaerated had liner correlations. The FVC% (r=0.68, P=0.01) and FEV₁% (r=0.64, P=0.01) to the MA_fibrosis had good linear correlations. (2) Compared to the values before treatment, the CO pattern score, volume and weight percentages of the extracted whole lung volume with attenuation values of the nonaerated area (V_nonated%, W_nonaerated%), the volume of poorly aerated and fibrosis lung tissue (V_fibrosis%, W_fibrosis%), the weight percentages of normal aerated lung (W_normal%), and the MA_fibrosis exhibited significant differences during the 3-6 month follow-up period.

CONCLUSION

The GGO and CO scored by the semiquantitative or quantitative analysis methods was similar. The HRCT quantitative analysis parameters showed a good correlation with the PFTs in ASS-OP patients, can provide an accurate OP pattern interpretation, and may be used as a monitoring and therapeutic indicator for ASS-OP patients.

Paraquat promotes acute lung injury in rats by regulating alveolar macrophage polarization through glycolysis

The present study investigates whether paraquat (PQ) regulates polarization of alveolar macrophages through glycolysis and promotes the occurrence of acute lung injury in rats. In vivo, the PQ intraperitoneal injection was used to construct a model of acute lung injury in rats. In vitro, the study measured the effect of different concentrations of PQ on the viability of the alveolar macrophages, and explored the polarization and glycolysis metabolism of alveolar macrophages at different time points after PQ intervention. Compared with the normal control (NC) group, the lung pathological damage in rats increased gradually after PQ poisoning, reaching a significant degree at 48 h after poisoning. The PQ-poisoned rat serum showed increased expressions of interleukin-6 (IL-6), tumor necrosis factor- α (TNF-α), and M1 macrophage marker, iNOS, while the expression of interleukin-10 (IL-10) and M2 macrophage marker, Arg1, decreased. The toxic effect of PQ on alveolar macrophages was dose- and time-dependent. Compared with the NC group, IL-6 and TNF-α in the cell supernatant gradually increased after PQ intervention, while the IL-10 content gradually decreased. The PQ intervention in alveolar macrophages increased the expression of intracellular glycolysis rate-limiting enzyme pyruvate kinase isozymes M1/M2 (PKM1/M2), lactate, lactate/pyruvate ratio, and the polarization of alveolar macrophage towards M1. Inhibition of cellular glycolysis significantly reduced the PQ-induced alveolar macrophage polarization to M1 type. Thus, PQ induced increased polarization of lung macrophages toward M1 and decreased polarization toward M2, promoting acute lung injury. Therefore, it can be concluded that PQ regulates the polarization of alveolar macrophages through glycolysis.

Effect of paraquat on cytotoxicity involved in oxidative stress and inflammatory reaction: A review of mechanisms and ecological implications

Paraquat (PQ) is a cheap and an effective herbicide, which is widely being used worldwide to remove weeds in cultivated crop fields. However, it can cause soil and water pollution, and pose serious harm to the environment and organisms. Several countries have started to limit or prohibit the use of PQ because of the increasing number of human deaths. Its toxicity can damage the organisms with a multi-target mechanism, which has not been fully understood yet. That is why it is hard to treat as well. The current research on PQ focuses on its targeted organ, the lungs, in which PQ mostly trigger pulmonary fibrosis. While there is a lack of systematic research, there are few studies published discussing its toxic effects at systematic level. This review summarizes the major damages caused by PQ in different organisms and partial mechanisms by which it causes these damages. For this purpose, we consulted several research articles that studied the toxicity of PQ in various tissues. We also listed some drugs that can be used to alleviate the toxicity of PQ. However, at present, the effectiveness of these drugs is still being explored in animal experiments and the study of their mechanism will also help in understanding the poisoning mechanism of PQ, which will ultimately lead to effective treatment in future.

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

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