Evaluation of suppressive effects of paraquat on innate immunity in Balb/c mice

Tripterygium wilfordii Hook.f. ameliorates paraquat-induced lung injury by reducing oxidative stress and ferroptosis via Nrf2/HO-1 pathway

Paraquat (PQ) poisoning can induce acute lung injury and fibrosis and has an extremely high mortality rate. However, no effective treatments for PQ poisoning have been established. In this study, the potential efficacy of Tripterygium wilfordii Hook.f. (TwHF) in alleviating PQ-induced lung injury and fibrosis was investigated in a mouse model. Mice were randomly assigned to the control, PQ, PQ + TwHF1 (pretreatment before inducing poisoning), and PQ + TwHF2 (treatment after poisoning) groups. The mice in the PQ + TwHF1 group were pretreated with TwHF for 5 days before receiving one dose of PQ (120 mg/kg) and then received a daily oral gavage of the indicated dosages of TwHF until sacrifice. The mice in the PQ + TwHF2 group were treated with TwHF 2 h after PQ exposure until sacrifice. The pathological analysis and Fapi PET/CT showed that treatment with TwHF attenuated lung injury. And TwHF reduced pulmonary oxidative stress, as indicated by the reduction in, malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS) levels, as well as by the increase in superoxide dismutase (SOD) levels. Accordingly, the Perls DAB staining showed increased iron concentrations and western blotting revealed a decreased GPX4 expression after PQ exposure, as well as the mitigation of the overexpression of Nrf2 and HO-1 induced by PQ. In conclusion, our study demonstrated the potential of TwHF as a treatment for PQ-induced lung injury and fibrosis. The protective mechanism of this medicinal herb may involve the regulation of ferroptosis.

Resolvin D1, therapeutic target in acute respiratory distress syndrome

Acute lung injury (ALI), or its more severe form, acute respiratory distress syndrome (ARDS), is a disease with high mortality and is a serious challenge facing the World Health Organization because there is no specific treatment. The excessive and prolonged immune response is the hallmark of this disorder, so modulating and regulating inflammation plays an important role in its prevention and treatment. Resolvin D1 (RvD1) as a specialized pro-resolving mediator has the potential to suppress the expression of inflammatory cytokines and to facilitate the production of antioxidant proteins by stimulating lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2). These changes limit the invasion of immune cells into the lung tissue, inhibit coagulation, and enhance cell protection against oxidative stress (OS). In particular, this biomolecule reduces the generation of reactive oxygen species (ROS) by blocking the activation of inflammatory transcription factors, especially nuclear factor-κB (NF-κB), and accelerating the synthesis of antioxidant compounds such as heme oxygenase 1 (HO-1) and superoxide dismutase (SOD). Therefore, the destruction and dysfunction of important cell components such as cytoplasmic membrane, mitochondria, Na+/k + adenosine triphosphatase (ATPase) and proteins involved in the phagocytic activity of scavenger macrophages are attenuated. Numerous studies on the effect of RvD1 over inflammation using animal models revealed that Rvs have both anti-inflammatory and pro-resolving capabilities and therefore, might have potential therapeutic value in treating ALI. Here, we review the current knowledge on the classification, biosynthesis, receptors, mechanisms of action, and role of Rvs in ALI/ARDS.

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.

Effects of quercetin loaded nanostructured lipid carriers on the paraquat-induced toxicity in human lymphocytes

Paraquat (PQ) as a herbicide and an environmental pollutant with increasing importance due to its toxicity to humans and animals. This study aimed to evaluate the protective and antioxidant activity of quercetin loaded Nanostructured Lipid Carriers (QNLC) against toxicity induced by PQ. Blood lymphocytes were prepared using Ficoll polysaccharide and subsequently by gradient centrifugation. The QNLC was prepared using an ultra-sonication method, which was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The viability, reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial membrane potential (MMP), lysosome membrane integrity, Bax and Bcl2 gene expression were evaluated in human isolated lymphocytes. The results showed spherical QNLCs with nano-size range (52.7 nm) and high drug encapsulation efficiency (98.5% -96%). The results also indicated that PQ induced cell death, as well as ROS production, decreased by QNLC in human lymphocytes. Also, QNLC meaningfully restored MMP reduction, lysosomal membrane destabilization, and lipid peroxidation and were capable of preventing PQ-treated change in Bax and Bcl2 gene expression. We report that QNLC, have a significantly higher capacity to prevent PQ-induced toxicity than Q itself. It is suggested that the QNLC is a promising antioxidant for drug delivery to be used as a therapeutic and prophylactic agent for PQ poisoning.

Acute lung injury: The therapeutic role of Rho kinase inhibitors

Acute lung injury (ALI) is a pulmonary illness with high rates of mortality and morbidity. Rho GTPase and its downstream effector, Rho kinase (ROCK), have been demonstrated to be involved in cell adhesion, motility, and contraction which can play a role in ALI. The electronic databases of Google Scholar, Scopus, PubMed, and Web of Science were searched to obtain relevant studies regarding the role of the Rho/ROCK signaling pathway in the pathophysiology of ALI and the effects of specific Rho kinase inhibitors in prevention and treatment of ALI. Upregulation of the RhoA/ROCK signaling pathway causes an increase of inflammation, immune cell migration, apoptosis, coagulation, contraction, and cell adhesion in pulmonary endothelial cells. These effects are involved in endothelium barrier dysfunction and edema, hallmarks of ALI. These effects were significantly reversed by Rho kinase inhibitors. Rho kinase inhibition offers a promising approach in ALI [ARDS] treatment.

Paraquat Preferentially Induces Apoptosis of Late Stage Effector Lymphocyte and Impairs Memory Immune Response in Mice

Paraquat (PQ) is a toxic non-selective herbicide. To date, the effect of PQ on memory immune response is still unknown. We investigated the impact of PQ on memory immune response. Adult C57BL/6 mice were subcutaneously injected with 2 mg/kg PQ, 20 mg/kg PQ or vehicle control every three days for two weeks. A single injection of keyhole limpet hemocyanin (KLH) at day four after the initial PQ treatment was used to induce a primary immune response; a second KLH challenge was performed at three months post the first KLH immunization to induce a secondary immune response. In steady state, treatment with 20 mg/kg PQ reduced the level of serum total IgG, but not that of IgM; treatment with 20 mg/kg PQ decreased the number of effector and memory lymphocytes, but not naïve or inactivated lymphocytes. During the primary immune response to KLH, treatment with 20 mg/kg PQ did not influence the proliferation of lymphocytes or expression of co-stimulatory molecules. Instead, treatment with 20 mg/kg PQ increased the apoptosis of lymphocytes at late stage, but not early stage of the primary immune response. During the secondary immune response to KLH, treatment with 20 mg/kg PQ reduced the serum anti-KLH IgG and KLH-responsive CD4 T cells and B cells. Moreover, effector or activated lymphocytes were more sensitive to PQ-induced apoptosis in vitro. Treatment with 2 mg/kg PQ did not impact memory immune response to KLH. Thus, treatment with 20 mg/kg PQ increased apoptosis of late stage effector cells to yield less memory cells and thereafter impair memory immune response, providing a novel understanding of the immunotoxicity of PQ.

Antioxidant and toxicity studies of biosynthesized cerium oxide nanoparticles in rats

PURPOSE

The purpose of this study was to investigate the acute toxic potential of cerium oxide nanoparticles (CNPs) synthesized by pullulan in adult male Wistar rats.

PATIENTS AND METHODS

Thirty male Wistar rats randomly were divided into five experimental groups of six animals each. The animals were received 50, 100, 200, and 400 mg/kg CNPs for 14 consecutive days. At the end of the experiment, the rats were euthanized and histopathological evaluation of the liver and renal tissues, as well ass, the markers of serum oxidative stress including thiobarbituric acid reactive substances, total sulfhydryl content, and antioxidant capacity (using ferric reducing/antioxidant power assay) were assessed. Hematological parameters and the activity of liver function enzymes were also measured.

RESULTS

The results of this study showed that CNPs caused no significant changes in the activity of liver enzymes, hepatic and renal histopathology and hematological parameters, while significantly improved serum redox status.

CONCLUSION

Acute administration of pullulan-mediated CNPs is safe and possess antioxidant activity.

Immunotoxicity of aflatoxin M1 : as a potent suppressor of innate and acquired immune systems in a subacute study

BACKGROUND

Although, to date, there have been several in vitro and in vivo studies of immunomodulatory effects of aflatoxin M₁ (AFB₁ ), little is known about the effect of AFM₁ on various aspects of innate and acquired immunity. In the present study, AFM₁ was administered intraperitoneally, at doses of 25 and 50 μg kg^-1 , body mass for 28 days and various immunological parameters were measured.

RESULTS

Several parameters related to immune function were suppressed: organ mass, cellularity of spleen, proliferation response to lipopolysaccaride and phytohemagglutinin-A, hemagglutination titer, delayed type of hypersensitivity response, spleen cell subtypes, serum hemolytic activity, serum immunoglobulin G level and cytokine production. AFM₁ did not cause changes in body mass, hematological parameters or the concentration of immunoglobulin M in blood serum.

CONCLUSIONS

Overall, the data suggested that AFM₁ suppressed innate and acquired immunity. Therefore, with respect to consumer safety, it is extremely important to further control the level of AFM₁ in milk, and this should be considered as a precedence for risk management actions. © 2018 Society of Chemical Industry.

Apigenin reverses lung injury and immunotoxicity in paraquat-treated mice

Paraquat (PQ) induces acute lung injury (ALI) and immunotoxicity. Apigenin exerts anti-oxidant and anti-inflammatory properties. The purpose of this study was to investigate the possible protective effects of apigenin on PQ-induced ALI and immunotoxicity in mice. Female C57BL/6 mice received a single injection of PQ (50 mg/kg). Apigenin was given for 7 consecutive days starting 5 days before PQ exposure. The toxicity markers were evaluated in terms of weight loss, lung histopathology, oxidative stress, inflammation, and T cell functions after PQ exposure. Poisoned mice exhibited severe lung tissue lesions, inflammatory cell infiltration and the release of pro-inflammatory cytokines IL-6 and TNF-α. PQ administration increased the lung wet/dry ratios and lipid peroxidation by the increase of MDA levels and decreased anti-oxidase activity including SOD, GSH-PX, and CAT. While such effect on lung was reversed by apigenin. Importantly, PQ-induced immunotoxicity was also observed in a decrease of spleen weight, inhibition of T cell proliferation and T-cell secreting IL-2 from splenocytes. Further mechanism analysis found that PQ administration could decrease total splenocytes, CD4⁺ and CD8⁺ T cells, SOD, GSH-PX, and CAT activity, and increased the levels of MDA and the concentrations of pro-inflammatory cytokines IL-6 and TNF-α compared to control mice. However, apigenin treatment reversed PQ-induced immunotoxicity. In summary, all results suggest that apigenin has beneficial effects on PQ-induced ALI and immunotoxicity possibly, and it could be related, at least in part, to its ability in modulating inflammation and oxidative stress, although in-depth studies might be needed to fully understand the mechanism of action.

A new sight for paraquat poisoning from immunology

Paraquat (methyl viologen, PQ) is highly toxic to humans. Pulmonary fibrosis is the most common cause of death after PQ poisoning. However, no effective therapy is available. The current treatment dilemma and pathology suggest that we should reconsider how to treat the poisoning using other methods, such as immunization. Some clues indicate that immune mechanisms may play important roles in the pathology of PQ poisoning. We implemented a simple experiment to test the hypothesis that activated innate immunity was involved in acute lung injury induced by PQ. Six rats were randomly distributed to two groups: PQ poisoning group and Immunosuppression group (cyclophosphamide pretreatment). Forty-eight hours after PQ administration, rats were anesthetized. The right lungs were excised for histopathology. The experimental results confirmed that in the set of immune deficiency, the inflammatory response in Immunosuppression group could not be effectively triggered so the lung pathology was much better than PQ poisoning group. The immunopathogenic mechanism of PQ poisoning may be essentially a sterile inflammation triggered and amplified by damage-associated molecular patterns (DAMPs). If the hypothesis is established, it may change the therapeutic regimen of PQ poisoning and the prognosis of patients.

Increase in the Th1-Cell-Based Immune Response in Healthy Workers Exposed to Low-Dose Radiation - Immune System Status of Radiology Staff

Objectives

Radiation is one of the most important sources of free radical (such as reactive oxygen species) production, which plays an essential role in the etiology of over hundred diseases. The aim of the study was to investigate some immune parameters and hematological indices in healthy workers of the Radiology Department, University Hospital of Mashhad, Iran.

Methods

The study was performed on 50 healthy workers: 30 radiology staff as the case group and 20 laboratory workers as the control group. The radiation dose received by the radiology staff participating in the study was less than the annual maximum permissible level, 50 millisievert. Hematological parameters, lymphocyte proliferation and cytokine production were studied in both groups.

Results

Among healthy radiology workers, the hematological indices did not differ statistically; however, their proliferation indices and IFN-γ levels showed significant increases in parallel with decreases in the IL-4 levels as compared to controls. The immune system of workers exposed to low-dose ionizing radiation was found to be shifted from a Type 2 to a Type 1 response to promote cellular immunity.

Conclusion

Based on our data, exposure to low-dose ionizing radiation may decrease the prevalence, frequency, and recurrence of various cancers and infectious diseases because of an increase in Th1-cell-based response, thus leading to more protection of the human body against tumor cells and foreign agents and possibly increased longevity. However, due to high rate of fluoroscopy use for interventional radiology, we suggest continuing research projects on radiation protection and hazards to prevent irreversible damage. As a recommendation, in future studies, radiology staff with a weakened immunity due to high radiation exposure should be considered as good choices to be treated using acupuncture techniques because acupuncture has been demonstrated to enhance the function and the number of immune cells.

Immune-Enhancing Effects of a High Molecular Weight Fraction of Cynanchum wilfordii Hemsley in Macrophages and Immunosuppressed Mice

The objective of this study was to investigate the immune-enhancing activity of a high molecular weight fraction (HMF) of Cynanchum wilfordii in RAW 264.7 macrophages and the cyclophosphamide (CYC)-induced mouse model of immunosuppression. To identify the bioactive substances of HMF, a crude polysaccharide (HMFO) was obtained and treated with sodium periodate (an oxidation agent) or digested with protease. In macrophages, HMF treatment enhanced the production of nitric oxide (NO) and cytokines (tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and interleukin 1β (IL-1β)), as well as phagocytic ability. In CYC-immunosuppressed mice, HMF improved relative spleen and thymus weights, natural killer (NK) cell activity, and splenic lymphocyte proliferation. These increases in NO and cytokines were mediated by up-regulation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Periodate treatment, but not protease treatment, decreased the immune-enhancing activity of HMFO, suggesting that polysaccharides are the active ingredients in C. wilfordii extract.

Paraquat Induces Apoptosis through a Mitochondria-Dependent Pathway in RAW264.7 Cells

Paraquat dichloride (N,N-dimethyl-4-4′-bipiridinium, PQ) is an extremely toxic chemical that is widely used in herbicides. PQ generates reactive oxygen species (ROS) and causes multiple organ failure. In particular, PQ has been reported to be an immunotoxic agrochemical compound. PQ was shown to decrease the number of macrophages in rats and suppress monocyte phagocytic activity in mice. However, the effect of PQ on macrophage cell viability remains unclear. In this study, we evaluated the cytotoxic effect of PQ on the mouse macrophage cell line, RAW264.7 and its possible mechanism of action. RAW264.7 cells were treated with PQ (0, 75, and 150 μM), and cellular apoptosis, mitochondrial membrane potential (MMP), and intracellular ROS levels were determined. Morphological changes to the cell nucleus and cellular apoptosis were also evaluated by DAPI and Annexin V staining, respectively. In this study, PQ induced apoptotic cell death by dose-dependently decreasing MMP. Additionally, PQ increased the cleaved form of caspase-3, an apoptotic marker. In conclusion, PQ induces apoptosis in RAW264.7 cells through a ROS-mediated mitochondrial pathway. Thus, our study improves our knowledge of PQ-induced toxicity, and may give us a greater understanding of how PQ affects the immune system.

Phytotrapy of cyclophosphamide-induced immunosuppression

Cyclophosphamide (CP) is a cytotoxic drug that can suppress both humoral and cellular immunity. Combining traditional medicinal herbs and chemotherapy drugs are used to improve immunity and quality of life performance status. In this paper, the effects of plant extracts, active components and their derivatives on immunosuppression of CP are discussed. Appropriate keywords were used to search through PubMed, Google Scholar, and Sciverse. All relevant results published from 1990 to date were chosen for final review. Over 50 references were found in which plant extracts, active components and their derivatives have been tested for their immune protective effects against CP-induced immune toxicity. Although there are several plants shown to be effective in animal models, no study was carried out on human subjects. According to the results; we can claim that plants and their active ingredients are good candidates for alternative adjuvant chemotherapy in reducing the immunotoxicity of CP.

Paraquat reduces natural killer cell activity via metallothionein induction

Paraquat (PQ), one of the most widely used herbicides, has been used for several decades in agriculture. Some studies suggest that PQ has effects on the immune system. Moreover, previous studies have shown that PQ imparted some immunosuppressive effects. In the present study, cytotoxicity assays using splenic NK cells from mice treated for 28 days with PQ (at 0.2, 1, and 5 mg/kg) were performed to determine whether PQ altered the function of NK cells. Given that PQ was expected to induce an immunosuppressive effect, it was hypothesized that a gene involved in cellular metal ion homeostasis, metallothionein-1 (MT-1), could play an important role in this outcome. This belief was based on the fact that MT1 encodes a protein responsible for zinc ion homeostasis, and that a reduction in free zinc ion levels impairs NK cell function. The results showed that PQ treatments led to increased MT expression in several organs (liver, kidneys, testes) and in splenocytes, caused a reduction of both free zinc ions in sera and in free intracellular zinc, and reduced the expression of GATA-3, a zinc-finger transcription factor important for maturation and activity of T-cells and NK cells. These results provide a basis for a new molecular mechanism to describe potential immunosuppressive effects of PQ in vivo.

Serum cytokine profiles of Khorasan veterans 23 years after sulfur mustard exposure

Sulfur mustard (SM) is an incapacitating chemical warfare agent that was used against Iranian soldiers during the period from 1983 to 1988. We have investigated serum cytokines profiles of Khorasan veterans who were exposed to SM >23 years earlier. Forty-four male Iranian veterans who had >40% disabilities due to delayed complications of SM poisoning and had disabilities were investigated. A total of 30 healthy male volunteers (relatives of the veterans) were selected as the control group. Cytokine levels were measured in the serum of case and control subjects using commercial ELISA kits. Hematologic parameters (white/red blood cell counts, hemoglobin levels, immune cell differentials) were also performed on blood samples from the study subjects. The results indicated that serum levels of ICAM-1 were significantly higher in the samples from SM-exposed veterans (772.8 [± 15.1] ng/ml [p=0.014] vs. control values of 710.2 [± 20.0] ng/ml). On the other hand, serum IL-1β, IL-8 levels and TNFα, were significantly lower for the veterans than the controls (IL-1β: 3.8 [± 0.1] vs. 4.3 [± 0.2] pg/ml, p=0.037; IL-8: 21.0 [± 6.1] vs. 84.6 [± 20.3] pg/ml, p=0.002; TNFα: 4.5 [± 0.1] vs. 5.5 [± 0.1] pg/ml, p=0.027). Levels of other assayed cytokines, e.g., IL-2, -4, -5, -6, -10, and -12, IFNγ, TNFβ, and sVCAM-1 were not significantly different between the study populations. None of the assayed hematologic parameters appeared to differ as well. It seems possible that dysfunctions could have been induced in the innate immune functions of the SM-exposed veterans as a result of these changes in cytokine expression and that these, in turn, may have contributed to the increased incidence of a myriad of diseases that have been documented in these veterans, including cancers. Future studies must focus on examining the significance of these changes in circulating cytokines and their potential contribution to the development of different diseases in veterans exposed to SM.

Proteomic analysis of changes in protein expression in serum from animals exposed to paraquat

Paraquat (PQ) poisoning remains a major public health concern in many countries. Extensive research has focused on finding early diagnostic biomarkers of acute PQ poisoning. In order to investigate the characterization of diagnostic biomarkers in PQ poisoning, we utilized proteomic analysis using serum from rats exposed to PQ, and we identified 8 differentially expressed proteins from over 500 protein spots. The expression of apolipoprotein E (ApoE), preprohaptoglobin (Pphg), a precursor of haptoglobin (Hp), and complement component 3 (C3) proteins was greatly induced by PQ exposure while the expression of fibrinogen γ-chain (FGG) and Ac-158 was dramatically reduced. To further investigate the possibility of ApoE, Pphg and FGG as useful diagnostic biomarkers of PQ poisoning, western blot and qRT-PCR analyses were conducted using cell lines as well as rat and human sera. The expression levels of ApoE, Hp and FGG were significantly altered in the presence of PQ in both rat and human serum suggesting that these proteins may be appropriate candidate molecular biomarkers for the early diagnosis of acute PQ intoxication.

Differential inflammatory responses triggered by toxic small molecules

PURPOSE

The aim of this study is to determine whether exposure to hazardous chemicals alters chemokine or cytokine production in macrophages and link these events to changes in intracellular signaling pathways and activation of specific gene promoters.

METHODS

RAW 264.7 mouse macrophages were treated with selected toxic industrial chemicals (TICs) and examined for changes in immune function. Luminex multiplex technology was used to assess changes in cytokine/chemokine expression and activation of kinase signaling pathways. In addition, a panel of macrophage cell lines with promoter-specific luciferase reporter genes were generated and treated with the TICs, and transcriptional responses to these chemicals were detected by changes in luminescence.

RESULTS

Changes in expression of cytokines and chemokines were linked to changes in the activation state of intracellular signaling pathways. Overall, the findings reveal that sublytic levels of TICs can alter the profile of cytokines and chemokines expressed by macrophages, with a pattern that suggests immunosuppression. The data demonstrate that critical changes in immune function correlate with activation of kinase signaling pathways in macrophages.

CONCLUSIONS

These data provide insight into the effects of sublytic doses of selected TICs on macrophage function, with a particular emphasis on identifying changes in expression of cytokines and chemokines. These altered patterns in immune function were linked to changes in the activation state of intracellular signaling pathways. The data strongly suggest that small amounts of TICs can have subtle, yet very critical, effects on macrophages.