Toxicokinetics and systematic responses of differently sized indium tin oxide (ITO) particles in mice via oropharyngeal aspiration exposure

Mitophagy and its regulatory mechanisms in the biological effects of nanomaterials

Mitophagy is a selective cellular process critical for the removal of damaged mitochondria. It is essential in regulating mitochondrial number, ensuring mitochondrial functionality, and maintaining cellular equilibrium, ultimately influencing cell destiny. Numerous pathologies, such as neurodegenerative diseases, cardiovascular disorders, cancers, and various other conditions, are associated with mitochondrial dysfunctions. Thus, a detailed exploration of the regulatory mechanisms of mitophagy is pivotal for enhancing our understanding and for the discovery of novel preventive and therapeutic options for these diseases. Nanomaterials have become integral in biomedicine and various other sectors, offering advanced solutions for medical uses including biological imaging, drug delivery, and disease diagnostics and therapy. Mitophagy is vital in managing the cellular effects elicited by nanomaterials. This review provides a comprehensive analysis of the molecular mechanisms underpinning mitophagy, underscoring its significant influence on the biological responses of cells to nanomaterials. Nanoparticles can initiate mitophagy via various pathways, among which the PINK1-Parkin pathway is critical for cellular defense against nanomaterial-induced damage by promoting mitophagy. The role of mitophagy in biological effects was induced by nanomaterials, which are associated with alterations in Ca2+ levels, the production of reactive oxygen species, endoplasmic reticulum stress, and lysosomal damage.

Subchronic toxicity study of indium-tin oxide nanoparticles following intratracheal administration into the lungs of rats

OBJECTIVES

We aimed to analyze the subchronic toxicity and tissue distribution of indium after the intratracheal administration of indium-tin oxide nanoparticles (ITO NPs) to the lungs of rats.

METHODS

Male Wistar rats were administered a single intratracheal dose of 10 or 20 mg In/kg body weight (BW) of ITO NPs. The control rats received only an intratracheal dose of distilled water. A subset of rats was periodically euthanized throughout the study from 1 to 20 weeks after administration. Indium concentrations in the serum, lungs, mediastinal lymph nodes, kidneys, liver, and spleen as well as pathological changes in the lungs and kidneys were determined. Additionally, the distribution of ionic indium and indium NPs in the kidneys was analyzed using laser ablation-inductively coupled plasma mass spectrometry.

RESULTS

Indium concentrations in the lungs of the 2 ITO NP groups gradually decreased over the 20-week observation period. Conversely, the indium concentrations in the mediastinal lymph nodes of the 2 ITO groups increased and were several hundred times higher than those in the kidneys, spleen, and liver. Pulmonary and renal toxicities were observed histopathologically in both the ITO groups. Both indium NPs and ionic indium were detected in the kidneys, and their distributions were similar to the strong indium signals detected at the sites of inflammatory cell infiltration and tubular epithelial cells.

CONCLUSIONS

Our results demonstrate that intratracheal administration of 10 or 20 mg In/kg BW of ITO NPs in male rats produces pulmonary and renal toxicities.

Nose-to-brain translocation and nervous system injury in response to indium tin oxide nanoparticles of long-term low-dose exposures

Indium tin oxide (ITO) is a semiconductor nanomaterial with broad application in liquid crystal displays, solar cells, and electrochemical immune sensors. It is worth noting that, with the gradual increase in worker exposure opportunities, the exposure risk in occupational production cannot be ignored. At present, the toxicity of ITO mainly focuses on respiratory toxicity. ITO inhaled through the upper respiratory tract can cause pathological changes such as interstitial pneumonia and pulmonary fibrosis. Still, extrapulmonary toxicity after nanoscale ITO nanoparticle (ITO NPs) exposure, such as long-term effects on the central nervous system, should also be of concern. Therefore, we set up exposure dose experiments (0 mg·kg-1, 3.6 mg·kg-1, and 36 mg·kg-1) based on occupational exposure limits to treat C57BL/6 mice via nasal drops for 15 weeks. Moreover, we conducted a preliminary assessment of the neurotoxicity of ITO NPs (20-30 nm) in vivo. The results indicated that ITO NPs can cause diffuse inflammatory infiltrates in brain tissue, increased glial cell responsiveness, abnormal neuronal cell lineage transition, neuronal migration disorders, and neuronal apoptosis related to the oxidative stress induced by ITO NPs exposure. Hence, our findings provide useful information for the fuller risk assessment of ITO NPs after occupational exposure.

A case report of Indium lung with progressive emphysema and fibrosis underwent lung unilateral transplantation 20 years after the end of the exposure

BACKGROUND

Indium lung is characterized by interstitial pneumonia and/or emphysema which occurs in indium-tin oxide (ITO) workers. Indium lung is now known to progress after stopping exposure to ITO, but the long-term influences of ITO remain unclear.

CASE PRESENTATION

Forty seven years old, a never-smoker, who had been engaged in an ITO manufacturing process for 8 years. Emphysema was indicated by the medical check-up for ex-ITO workers, and he was diagnosed with indium lung. He underwent partial lung resections for pneumothorax two times, and obstructive pulmonary dysfunction had progressed through the years. He underwent right single lung transplant 20 years after ITO exposure. Pathologically, his lung showed severe distal acinar emphysema and honeycomb change. Fibrosis and destruction of the lung tissue significantly progressed compared to the previous partial resections. Scanning electron microscopy combined with energy dispersive spectroscopy revealed that the deposited particles contained indium and tin. After the transplantation, his respiratory function was improved.

CONCLUSIONS

In this case, ITO resided in the lung tissue for 20 years, and lung tissue destruction kept progressing. Careful medical follow-up is recommended for ITO-workers even if they are asymptomatic.

Toxicokinetics, dose-response, and risk assessment of nanomaterials: Methodology, challenges, and future perspectives

The rapid growth of nanomaterial applications has raised safety concerns for human health. A number of studies have been conducted to assess the toxicokinetics, toxicology, dose-response, and risk assessment of different nanomaterials using in vitro and in vivo animal and human models. However, current studies cannot meet the demand for efficient assessment of toxicokinetics, dose-response relationships, or the toxicological risk arising from the rapidly increasing number of newly synthesized nanomaterials. In this article, we review the methods for conducting toxicokinetics, hazard identification, dose-response, exposure, and risk assessment studies of nanomaterials, identify the knowledge gaps, and discuss the challenges remaining. We provide the rationale behind the appropriate design of nanomaterial plasma toxicokinetic and tissue distribution studies, including caveats on the interpretation and correlation of in vitro and in vivo toxicology studies. The potential of using physiologically based pharmacokinetic (PBPK) models to extrapolate toxicokinetic and toxicity findings from in vitro to in vivo and from animals to humans is discussed, and the knowledge gaps of PBPK modeling for nanomaterials are identified. While challenges still exist, there has been progress in the toxicokinetics, hazard identification, and risk assessment of nanomaterials in the past two decades. Recent advancements in the field are highlighted with relevant examples. We also share latest guidelines as well as our perspectives on future studies needed to characterize the toxicokinetics, toxicity, and dose-response relationship in support of nanomaterial risk assessment. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.