Deltamethrin Increases Candida albicans infection susceptibility in mice

Association between prenatal exposure to indoor residual spraying insecticides and infection rates among South African children participating in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE)

In 2021, 53 countries conducted indoor residual spraying (IRS), the application of insecticides such as dichlorodiphenyl trichloroethane (DDT) or pyrethroids to the walls of homes to control malaria. Animal studies show that these insecticides can increase susceptibility to infections but only one human study was conducted in a population from an area where IRS is applied. The aim of the present study was thus to investigate whether maternal exposure to DDT, its breakdown product dichlorodiphenyl dichloroethylene (DDE) or pyrethroid insecticides is associated with symptoms of infection among children living in a region of South Africa were IRS is conducted annually. As part of the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) we measured maternal serum concentrations of DDT and DDE, and urinary concentrations of four pyrethroid metabolites in peripartum samples. Poisson regression models with robust variance estimates were used to investigate associations with the rates of infection symptoms between ages 3.5-5 years among 629 children as assessed based on caregiver interviews. Multiple pyrethroid metabolites were associated with infection symptoms. For instance, cis-DBCA was associated with increased rates of ear infection (Incidence Rate Ratio for a 10-fold increase (IRR10) = 1.4; 95 % Confidence Interval (CI) = 1.0, 2.1) and persistent diarrhea (IRR10 = 2.1; 95 % CI = 1.2, 3.9), trans-DCCA was associated with increased rates of colds in children (IRR10 = 1.3; 95 % CI = 1.0, 1.6) and persistent fever (IRS10 = 1.4; 95 % CI = 1.0, 2.0), and 3-PBA was associated with increased rates of persistent fever (IRR10 = 1.8; 95 % CI = 1.0, 3.0). We found limited evidence of association between maternal DDE and DDT serum concentrations and infection symptoms. Results suggest that prenatal exposure to pyrethroid insecticides may be associated with infections among children from an area where IRS is conducted.

Toxicological assessment of sublethal dose of acetamiprid in male mice and the efficacy of quercetin

Acetamiprid (ACP) is a neonicotinoid insecticide that is the most effective pesticide for crop protection as well as flea control in agricultural animals and pets in the world. The goal of this study was to look at the in vivo effects of a sublethal dose of ACP on hematotoxicity, oxidative stress, hepatotoxicity, nephrotoxicity, immunotoxicity, and histological alterations, as well as the role of quercetin (QE) in alleviating these effects. Twenty adult male mice were divided into four equal groups orally administered corn oil (control), QE (50 mg kg^-1 b.wt.), ACP (1/10 LD₅₀) or ACP plus QE for two weeks. The results showed that ACP significantly lowered the body weight gain, hematological indices, glutathione (GSH), and both cellular and humoral immunity, On the other hand, levels of lipid peroxidation (LPO), glutathione peroxidase (GPx), and liver and kidney marker values were considerably increased in male mice exposed to ACP. In addition, examination under light microscopic showed that ACP induces histological alterations in liver and kidney tissues. The results also revealed that treating intoxicated mice with QE significantly reduced the deleterious effects of ACP. In conclusion, current results show that ACP at the sub lethal dose poses toxic risks to the liver and kidneys, and QE as a natural material enhances antioxidant defenses, which can be used as a potential interventional therapy against negative effects of pesticides like ACP.

Effect of diosmin on lipid peoxidation and organ damage against subacute deltamethrin exposure in rats

The aim of this study was to investigate the protective efficacy of diosmin against subacute deltamethrin exposure. For this purpose, 40 male Wistar albino rats were used. The animals were assigned to the following 4 groups: control group (received corn oil vehicle alone), diosmin-treated group (50 mg/kg bw/day orally), deltamethrin-exposed group (5 mg/kg bw/day, orally) and coadministered group (5 mg/kg bw/day deltamethrin and 50 mg/kg bw/day diosmin, orally) for 28 days. Some lipid peroxidation/antioxidant status/biochemical markers were evaluated in blood/tissue (liver, kidney, brain, heart and testis) samples and the histopathological architecture was assessed. Compared with the control group, no alteration was detected in the parameters and histological findings of the diosmin-treated group. Deltamethrin toxicity was associated with significantly increased plasma, cardiac, hepatic, renal, cerebral and testicular levels of MDA and NO, and significantly decreased GSH levels (p < 0.05). Antioxidant enzyme status (SOD, CAT and GSH-Px activities) displayed either decrease or increase (p < 0.05). Significant increase was detected in AST and ALT activities and urea and creatinine levels (p < 0.05). The values of the group coadministered with deltamethrin and diosmin were similar to the values of the control group. Diosmin ameliorated deltamethrin-induced lymphocytic and histiocytic infiltration and subendocardial oedema in the heart. Combined administration also minimized hepatic, renal, testicular and cerebral histopathological findings. The alterations detected in various toxicological parameters correlated well with the histopathological changes observed in various organs. In conclusion, it is suggested that diosmin could provide protection against deltamethrin-induced toxicity and organ damage in rats.

Maternal Peripartum Serum DDT/E and Urinary Pyrethroid Metabolite Concentrations and Child Infections at 2 Years in the VHEMBE Birth Cohort

BACKGROUND

Indoor residual spraying (IRS) of insecticides, conducted in low- and middle-income countries to control malaria, may result in high exposure to dichlorodiphenyltrichloroethane (DDT), its breakdown product dichlorodiphenyldichloroethylene (DDE), or pyrethroids. Animal studies suggest in utero exposure to these chemicals may increase childhood infection frequency.

OBJECTIVES

We investigated associations between maternal DDT/E and pyrethroid metabolite concentration and child infection associations in an IRS setting in which susceptibility factors are common and infections are leading causes of child morbidity and mortality.

METHODS

Using gas chromatography-mass spectrometry, we measured serum DDT/E and urinary pyrethroid metabolite concentrations in peripartum samples from 674 women participating in the Venda Health Examination of Mother, Babies and their Environment (VHEMBE) study. Counts of persistent child fevers, otitis media, and severe sore throat between 1 and 2 y of age were ascertained from maternal interviews. Associations between DDT/E and pyrethroid metabolite concentrations and infections were estimated using zero-inflated Poisson regression. We estimated relative excess risks due to interaction (RERI) with poverty, maternal energy intake, and maternal HIV status.

RESULTS

Concentrations of DDT/E, particularly p,p'-DDE, were associated with higher rates of persistent fevers [IRR=1.21 (95% CI: 1.01, 1.46)], for a 10-fold increase in p,p'-DDE). This association was stronger among children from households below versus above the South African food poverty line [IRR=1.31 (95% CI: 1.08, 1.59) vs. IRR=0.93 (95% CI: 0.69, 1.25), respectively] and for children whose mothers had insufficient versus sufficient caloric intake during pregnancy [IRR=1.30 (95% CI: 1.07, 1.58) vs. IRR=0.96 (95% CI: 0.72, 1.28), respectively].

CONCLUSIONS

In utero IRS insecticide exposure may increase childhood infection rates. This was particularly apparent among children from poorer households or whose mothers had low energy intake during pregnancy. https://doi.org/10.1289/EHP2657.

Cis-bifenthrin induces immunotoxicity in adolescent male C57BL/6 mice

Bifenthrin (BF) is an important synthetic pyrethroid. Previous studies have demonstrated that cis-BF exhibits toxic effects on development, the neurological, reproductive and endocrine system. In this study, we evaluated the immunotoxicity caused by cis-BF in adolescent male C57BL/6 mice. Mice were exposed orally to 0, 5, 10, and 20 mg/kg/d for 3 weeks. The results showed that body weight, spleen weight, and splenic cellularity decreased in mice exposed to 20 mg/kg/d cis-BF. Additionally, we found that the mRNA levels of the pro-inflammatory factors IL-1β, IL-6, CXCL-1, and TNF-α, in peritoneal macrophages, the spleen, and the thymus were inhibited in the cis-BF-treated groups. Moreover, MTT assays demonstrated that cis-BF inhibited splenocyte proliferation stimulated by LPS or Con A, as well as the secretion of IFN-γ on Con A stimulation. Collectively, the results of this study suggest that exposure to cis-BF has the potential to induce immunotoxicity in adolescent male C57BL/6 mice.

Cis-bifenthrin causes immunotoxicity in murine macrophages

Synthetic pyrethroids (SPs) are commonly used insecticides that have been detected in mammals, including humans, indicating a potential threat to human health. Bifenthrin (BF), as well as other pyrethroids, has been shown to possess neurotoxic, reproductive, hepatotoxic and nephrotoxic potential in mammals. However, studies regarding the immunotoxicity of BF and its mechanism are limited. In this study, we aim to exam the immunotoxicity of cis-BF on the murine macrophage cell line, RAW 264.7. MTT assay results demonstrated that cis-BF exposure induced apoptosis in RAW 264.7 cells in a concentration-dependent manner. We found that the expression of p53 and caspase-3 was up-regulated, while the expression of Bcl-2 was down-regulated during cis-BF-induced apoptosis. In addition, we also found that cis-BF exposure caused oxidative stress in RAW 264.7 cells in a dose-dependent manner. Interestingly, cis-BF exposure was found to inhibit the increase in transcription levels of IL-1β, IL-6 and TNF-α responding to LPS stimulation. We also found that the induced increase in IFN-β mRNA levels upon Sendai virus infection was blocked with cis-BF exposure. Finally, we found that cis-BF exposure increased ROS levels and dysregulated mRNA levels of oxidative stress-related genes in RAW 264.7 cells. The present study elucidates the immunotoxicity effect of cis-BF on macrophages and its possible underlying mechanism. The results from this study support the necessity to evaluate immune dysfunction in the risk assessment of cis-BF exposure.

Pesticides and Ostreid Herpesvirus 1 Infection in the Pacific Oyster, Crassostrea gigas

Since 2008, mass mortality outbreaks have been reported in all French regions producing Pacific oysters, and in several Member States of the European Union. These mass mortality events of Pacific oysters are related to OsHV-1 infection. They occur during spring and summer periods leaving suspect the quality of the marine environment and the role of seasonal use of pesticides associated with the arrival of freshwater in oyster rearing areas. Pesticides have been also detected in French coastal waters, especially in areas of oyster production. Using PMA real-time PCR we showed that a mixture of 14 pesticides has no effect on the integrity of virus capsids from viral suspension in the conditions tested. A contact of oysters with this pesticide mixture was related to higher mortality rates among experimentally infected animals in comparison with control ones (no previous pesticide exposure before experimental infection). We therefore suggest that pesticides at realistic concentration can exert adverse effects on Pacific oysters and causes an increased susceptibility to the viral infection in experimental conditions.

Melatonin Reverses Fas, E2F-1 and Endoplasmic Reticulum Stress Mediated Apoptosis and Dysregulation of Autophagy Induced by the Herbicide Atrazine in Murine Splenocytes

Exposure to the herbicide Atrazine (ATR) can cause immunotoxicity, apart from other adverse consequences for animal and human health. We aimed at elucidating the apoptotic mechanisms involved in immunotoxicity of ATR and their attenuation by Melatonin (MEL). Young Swiss mice were divided into control, ATR and MEL+ATR groups based on daily (x14) intraperitoneal administration of the vehicle (normal saline), ATR (100 mg/kg body weight) and MEL (20 mg/kg body weight) with ATR. Isolated splenocytes were processed for detection of apoptosis by Annexin V-FITC and TUNEL assays, and endoplasmic reticulum (ER) stress by immunostaining. Key proteins involved in apoptosis, ER stress and autophagy were quantified by immunoblotting. ATR treatment resulted in Fas-mediated activation of caspases 8 and 3 and inactivation of PARP1 which were inhibited significantly by co-treatment with MEL. MEL also attenuated the ATR-induced, p53 independent mitochondrial apoptosis through upregulation of E2F-1 and PUMA and suppression of their downstream target Bax. An excessive ER stress triggered by ATR through overexpression of ATF-6α, spliced XBP-1, CREB-2 and GADD153 signals was reversed by MEL. MEL also reversed the ATR-induced impairment of autophagy which was indicated by a decline in BECN-1, along with significant enhancement in LC3B-II and p62 expressions. Induction of mitochondrial apoptosis, ER stress and autophagy dysregulation provide a new insight into the mechanism of ATR immunotoxicity. The cytoprotective role of MEL, on the other hand, was defined by attenuation of ER stress, Fas-mediated and p53 independent mitochondria-mediated apoptosis as well as autophagy signals.

Insecticide resistance alleles affect vector competence of Anopheles gambiae s.s. for Plasmodium falciparum field isolates

The widespread insecticide resistance raises concerns for vector control implementation and sustainability particularly for the control of the main vector of human malaria, Anopheles gambiae sensu stricto. However, the extent to which insecticide resistance mechanisms interfere with the development of the malignant malaria parasite in its vector and their impact on overall malaria transmission remains unknown. We explore the impact of insecticide resistance on the outcome of Plasmodium falciparum infection in its natural vector using three An. gambiae strains sharing a common genetic background, one susceptible to insecticides and two resistant, one homozygous for the ace-1(R) mutation and one for the kdr mutation. Experimental infections of the three strains were conducted in parallel with field isolates of P. falciparum from Burkina Faso (West Africa) by direct membrane feeding assays. Both insecticide resistant mutations influence the outcome of malaria infection by increasing the prevalence of infection. In contrast, the kdr resistant allele is associated with reduced parasite burden in infected individuals at the oocyst stage, when compared to the susceptible strain, while the ace-1 (R) resistant allele showing no such association. Thus insecticide resistance, which is particularly problematic for malaria control efforts, impacts vector competence towards P. falciparum and probably parasite transmission through increased sporozoite prevalence in kdr resistant mosquitoes. These results are of great concern for the epidemiology of malaria considering the widespread pyrethroid resistance currently observed in Sub-Saharan Africa and the efforts deployed to control the disease.