Potential toxicity and safety evaluation of nanomaterials for the respiratory system and lung cancer

Crocin averts functional and structural rat hepatic disturbances induced by copper oxide nanoparticles

Background

Exposure to nanoparticles became inevitable in our daily life due to their huge industrial uses. Copper oxide nanoparticles (CuONPs) are one of the most frequently utilized metal nanoparticles in numerous applications. Crocin (CRO) is a major active constituent in saffron having anti-inflammatory and antioxidant potentials.

Objectives

We designed this study to explore the probable defensive role of CRO against CuONPs-induced rat hepatic damage.

Materials and methods

Therefore, 24 adult rats were randomly distributed into 4 equal groups as negative control, CRO, CuONPs, and co-treated CuONPs with CRO groups. All treatments were administered for 14 days. The hepatotoxic effect of CuONPs was evaluated by estimation of hepatic alanine aminotransferase and aspartate aminotransferase enzymes, hepatic oxidative malondialdehyde and antioxidant glutathione reduced, serum levels of inflammatory biomarkers (tumor necrosis factor-alpha, interleukin-1-beta, and nuclear factor kappa B), and expression of the apoptotic BAX in hepatic tissues; in addition, histopathological examination of the hepatic tissues was conducted.

Results

We found that concurrent CRO supplement to CuONPs-treated rats significantly averted functional and structural rat hepatic damage as documented by decreased hepatic enzymes activities, restored hepatic oxidant/antioxidant balance, decreased serum levels of inflammatory biomarkers, reversed BAX-mediated apoptotic cell death in hepatic tissues along with repair of CuONPs-induced massive hepatic structural and ultrastructural alterations.

Conclusions

It is concluded that combined CRO supplement to CuONPs-treated rats improved hepatic function and structure by, at least in part, antioxidant, anti-inflammatory, and antiapoptotic mechanisms.

Silver Nanoparticles Induce DNA Hypomethylation through Proteasome-Mediated Degradation of DNA Methyltransferase 1

Nanoparticles are used in many fields and in everyday products. Silver nanoparticles are the most frequently used nanoparticles; for example, in food-related products, owing to their antibacterial activity. However, it has been pointed out that they might have unexpected biological effects, and evaluation of their effects is underway. Although there is a growing body of evidence that nanoparticles can also induce epigenetic changes, there is still little information on the underlying mechanisms. Here, we evaluated changes in DNA methylation induced by silver nanoparticles and attempted to elucidate the induction mechanism. Immunofluorescence staining analysis revealed that silver nanoparticles with a diameter of 10, 50, or 100 nm (nAg10, nAg50, and nAg100, respectively) decreased the content of methylated DNA in A549 alveolar epithelial cells. The level of DNA methyltransferase 1 (Dnmt1) protein, which is involved in maintaining methylation during DNA replication, was significantly decreased, whereas that of Dnmt3b, which is responsible for de novo DNA methylation, was significantly increased by nAg10 treatment. Co-treatment with nAg10 and cycloheximide, which inhibits translation by inhibiting the translocation step of protein synthesis, decreased the level of Dnmt1 in comparison with nAg10-treated A549 cells, indicating a post-translational effect of nAg10. Furthermore, pretreatment with the proteasome inhibitor lactacystin restored the levels of Dnmt1 protein and DNA methylation in nAg10-treated cells. Collectively, these results suggest that nAg10 induced DNA hypomethylation through a proteasome-mediated degradation of Dnmt1.

A 75 year old male with recurrent unilateral pleural effusion and positive ANA

This case report describes the clinical course and diagnostic challenges arising in a 75 year old man who initially presented with progressive shortness of breath. Imaging revealed a pleural effusion, which was recurrent following thoracentesis. While his initial workup suggested an autoimmune etiology, further diagnostic testing revealed a diagnosis of malignant pleural mesothelioma. Curiously, the patient had no known asbestos exposure, which is classically associated with acquired mesothelioma. There are a small number of similar cases with a possible overlap between positive autoimmune serologies and mesothelioma; however, the underlying pathophysiology remains elusive. It is the authors' goal to contribute this case to the few cases describing such overlap syndromes.

Systematic Review of Screening and Surveillance Programs to Protect Workers from Nanomaterials

Background

Screening and surveillance approaches for workers exposed to nanomaterials could aid in early detection of health effects, provide data for epidemiological studies and inform action to decrease exposure. The aim of this review is to identify such screening and surveillance approaches, in order to extract available data regarding (i) the studies that have successfully been implemented in present day, (ii) identification of the most common and/or toxic nano-related health hazards for workers and (iii) possible exposure surveillance markers. This review contributes to the current understanding of the risk associated with nanomaterials by determining the knowledge gap and making recommendations based on current findings.

Methods

A systematic review was conducted. PubMed and Embase were searched to identify articles reporting on any surveillance-related study that described both exposure to nanomaterials and the health indicators that were measured. Four reviewers worked in pairs to independently assess the eligibility of studies and risk of bias before extraction of data. Studies were categorised according to the type of study and the medical surveillance performed, which included the type of nanomaterial, any exposure details provided, as well as health indicators and biomarkers tested.

Results

Initially 92 studies were identified, from which 84 full texts were assessed for eligibility. Seven studies met all the inclusion criteria, i.e. those performed in Taiwan, Korea, Czech Republic and the US. Of these, six compared health indicators between exposed and unexposed workers and one study described a surveillance program. All studies were at a high risk of bias. Workers were exposed to a mix of nanomaterials in three studies, carbon-based nanomaterials in two studies, nano-silver in one study and nano-titanium oxide in the other study. Two studies did not find a difference in biomarkers between exposed and unexposed workers. In addition, differences in early effects on pulmonary function or neurobehavioral tests were not observed. One study found an increased prevalence of allergic dermatitis and “sneezing” in the exposed group.

Conclusions

This review of recently published data on surveillance studies proves that there is a gap in the current knowledge, where most of the surveillance-related studies reported do not follow a set format that provides the required information on ENM characterisation, the type of exposure and the measured indicators/biomarkers. Hence, there is very low quality evidence that screening and surveillance might detect adverse health effects associated with workplace exposure. This systematic review is relevant because it proves that, although surveillance programs have been initiated and preliminary results are being published, the current studies are actually not answering the important questions or solving the overall problem regarding what the potential health hazards are among workers either handling or potentially exposed to ENMs. The recommendations, thus proposed, are based on an obvious need for (i) exposure registries, where longitudinal follow-up studies should inform surveillance, (ii) known exposure measurements or summary indices for ENMs as a reference (iii) validation of candidate biomarkers and (iv) studies that compare the effects of these surveillance approaches to usual care, e.g. those commonly followed for bulk-size hazardous materials.