ZnO nanoparticles alter redox metabolism of Limnoperna fortunei

ZnO NPs induce miR-342-5p mediated ferroptosis of spermatocytes through the NF-κB pathway in mice

BACKGROUND

Zinc oxide nanoparticle (ZnO NP) is one of the metal nanomaterials with extensive use in many fields such as feed additive and textile, which is an emerging threat to human health due to widely distributed in the environment. Thus, there is an urgent need to understand the toxic effects associated with ZnO NPs. Although previous studies have found accumulation of ZnO NPs in testis, the molecular mechanism of ZnO NPs dominated a decline in male fertility have not been elucidated.

RESULTS

We reported that ZnO NPs exposure caused testicular dysfunction and identified spermatocytes as the primary damaged site induced by ZnO NPs. ZnO NPs led to the dysfunction of spermatocytes, including impaired cell proliferation and mitochondrial damage. In addition, we found that ZnO NPs induced ferroptosis of spermatocytes through the increase of intracellular chelatable iron content and lipid peroxidation level. Moreover, the transcriptome analysis of testis indicated that ZnO NPs weakened the expression of miR-342-5p, which can target Erc1 to block the NF-κB pathway. Eventually, ferroptosis of spermatocytes was ameliorated by suppressing the expression of Erc1.

CONCLUSIONS

The present study reveals a novel mechanism in that miR-342-5p targeted Erc1 to activate NF-κB signaling pathway is required for ZnO NPs-induced ferroptosis, and provide potential targets for further research on the prevention and treatment of male reproductive disorders related to ZnO NPs.

Immune response to zinc oxide inhalation in metal fume fever, and the possible role of IL-17f

Metal fume fever (MFF) is a work-related disease caused by the inhalation of metal particles, including zinc oxide. Chronic asthma may develop as a long-term consequence of exposure, particularly for welders and metal workers who are most at risk. In this study, we investigated the effects of ZnO fume inhalation on multiple inflammation-related cytokine- and cytokine receptor genes in mice from lung and lymph node samples, to explore the role of these in the pathogenesis of MFF. In our experiments, the animals were treated with a sub-toxic amount of ZnO fume for 4 h a day for 3 consecutive days. Sampling occurred 3 and 12 h post-treatment. We are the first to demonstrate that ZnO inhalation causes extremely increased levels of IL-17f gene expression at both sampling time points, in addition to increased gene expression rates of several other interleukins and cytokines, such as IL-4, IL-13, CXCL5, CSF-3, and IFN-γ. Our animal experiment provides new insights into the immunological processes of early metal fume fever development. IL-17f plays a crucial role in connecting immunological and oxidative stress events. The increased levels of IL-4 and IL-13 cytokines may explain the development of long-term allergic asthma after exposure to ZnO nanoparticles, which is well-known among welders, smelters, and metal workers.

Acute Exposure to Two Biocides Causes Morphological and Molecular Changes in the Gill Ciliary Epithelium of the Invasive Golden Mussel Limnoperna fortunei (Dunker, 1857)

Limnoperna fortunei, the golden mussel, is a bivalve mollusk considered an invader in South America. This species is responsible for ecological and economic damages due to its voluminous fouling capability. Chemical biocides such as MXD-100™ and sodium dichloroisocyanurate (NaDCC) are often used to control L. fortunei infestations in hydraulic systems. Thus, we proposed to investigate the effects of different periods (24, 48 and 72 h) of exposure to MXD-100™ (0.56 mg L-1) and NaDCC (1.5 mg L-1) on the gills of L. fortunei through morphological and molecular analyses. NaDCC promoted progressive morphological changes during the analyzed periods and only an upregulation of SOD and HSP70 expression during the first 24 h of exposure. MXD-100™ led to severe morphological changes from the first period of exposure, in addition to an upregulation of SOD, CAT, HSP70 and CYP expression during the first 24 h. In contrast, MXD-100™ led to a downregulation of CAT transcription between 24 and 48 h. In static conditions, NaDCC causes lethal damage after 72 h of exposure, and that exposure needs to be continuous to achieve the control of the species. Meanwhile, the MXD-100™ treatment presented several effects during the first 24 h, showing acute toxicity in a shorter period of time.

Polystyrene microplastic alters the redox state and arsenic metabolization in the freshwater bivalve Limnoperna fortunei

Most organisms possess the capacity to metabolize arsenic (As) accumulating compounds to less toxic forms, thus minimizing the adverse effect induced by this metalloid. However, other contaminants may to interfere with As metabolism, contributing to the accumulation of more toxic compounds. Microplastics (MPs) are omnipresent in aquatic environment and may induce toxicological effects (alone or in combination with other contaminants) on living organisms. Therefore, the objective of the present study was to evaluate the effect of the exposure of the freshwater clam Limnoperna fortunei to a combination of MP (4 and 40 μg/L of polystyrene microbeads, 1.05 μm) and As (50 μg/L) for 48 h, evaluating the accumulation and metabolization of As and oxidative stress parameters, such as catalase (CAT), glutathione-S-transferase activities, total antioxidant competence, reduced glutathione (GSH), and lipid damage in the gills and digestive glands. Results revealed that low MP concentration disrupts the redox state of the digestive gland by a decrease in the antioxidant activity (CAT and total antioxidant capacity). GSH levels in the gills of animals exposed to MP (4 μg/L) alone and the combination of MP + As increased, concomitant with an increase in the percentage of toxic compounds, indicating the effect of MP on As metabolism. Although, few studies evaluated the effect of coexposure to MP + As by considering metabolization of metalloid in freshwater bivalve, our results revealed that exposure to MP reduced the metabolization capacity of As, favoring the accumulation of more toxic compounds besides the MP alone, which showed a pro-oxidant effect in L. fortunei.

Metal-oxide inhalation induced fever - Immuntoxicological aspects of welding fumes

Metal fume fever is a well-known occupational disease that arises from prolonged exposure to subtoxic levels of zinc oxide-containing fumes or dust. This review article aims to identify and examine the possible immunotoxicological effects of inhaled zinc oxide nanoparticles. The current most widely accepted pathomechanism for the development of the disease involves the formation of reactive oxygen species following the entry of zinc oxide particles into the alveolus resulting the release of pro-inflammatory cytokines by activation of the Nuclear Factor Kappa B transcriptional signal, thus evoking the symptoms. The role of metallothionein in inducing tolerance is believed to be a key factor in mitigating the development of metal fume fever. The other, poorly proven hypothetical route is that zinc-oxide particles bind to an undefined protein in the body as haptens to form an antigen and act as an allergen. After activation of the immune system, primary antibodies and immune complexes are developed and type 1. hypersensitivity reaction occurs, that can cause asthmatic dyspnoea, urticaria and angioedema. The development of tolerance is explained by the formation of secondary antibodies against primary antibodies. Oxidative stress and immunological processes cannot be completely separated from each other, as they can induce each other.

Salinity variation modulates cellular stress response to ZnO nanoparticles in a sentinel marine bivalve, the blue mussel Mytilussp

Zinc oxide nanoparticles are released into marine environments from industrial, medical and consumer uses sparking concerns about their potential ecotoxicological effects. Ecological hazard assessment of nZnO in marine ecosystems is hindered by the lack of understanding of the potential interactive effects of nZnO toxicity with other common abiotic stressors, such as salinity fluctuations, in marine organisms. To close this gap in our knowledge, we carried out a comprehensive biomarker-based assessment of the combined effects of salinity and nZnO in a sentinel marine bivalve, the blue mussels Mytilus edulis. The mussels were exposed for 21 days to clean seawater (control), an environmentally relevant concentration (100 μg Zn l^-1) of nZnO or dissolved Zn (to identify the toxic effects attributable to Zn²⁺ toxicity) under the normal (15), low (5) and fluctuating (5-15) salinity regimes. The selected molecular and biochemical markers focused on the oxidative stress, apoptosis, detoxification system and inflammation in the gills and the digestive gland of the mussels. Biomarker analysis showed different effects of nZnO and dissolved Zn on biomarkers of oxidative stress, xenobiotic detoxification and apoptosis but similar effects of both pollutants on the levels of metallothioneins and inflammatory markers. Exposure to nZnO led to elevated levels of lipid peroxidation, upregulation of p53 and p38 stress kinases and apoptosis-related genes, most notably in the gills. Exposure to dissolved Zn led to accumulation of protein carbonyls and activated redox-sensitive detoxification enzymes (NADPH-P450 reductase and glutathione-S-transferase) in the mussels. The ambient salinity had significant effects the cellular adverse effects of nZnO in the mussels. The nZnO-induced cellular stress was detectable under the normal (15) and fluctuating (5-15) salinity conditions in the studied brackish water population of the mussels. At low salinity (5), nZnO toxicity signal was almost completely dampened. These findings indicate that chronic osmotic stress close to the tolerance limits of M. edulis prevails over the effects of the environmentally relevant nZnO and dissolved Zn concentrations in combined exposures. These stressor interactions might ameliorate the cellular toxicity of nZnO in the mussels but limit applicability of cellular stress biomarkers for detecting the toxic effects of nanopollutants in low salinity habitats.