Role of inflammation in the malignant transformation of pleural mesothelial cells induced by multi-walled carbon nanotubes

Celastrol reduces lung inflammation induced by multiwalled carbon nanotubes in mice via NF-κb-signaling pathway

Multiwalled carbon nanotubes (MWCNTs) have numerous applications in the field of carbon nanomaterials. However, the associated toxicity concerns have increased significantly because of their widespread use. The inhalation of MWCNTs can lead to nanoparticle deposition in the lung tissue, causing inflammation and health risks. In this study, celastrol, a natural plant medicine with potent anti-inflammatory properties, effectively reduced the number of inflammatory cells, including white blood cells, neutrophils, and lymphocytes, and levels of inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, in mice lungs exposed to MWCNTs. Moreover, celastrol inhibited the activation of the NF-κB-signaling pathway. This study confirmed these findings by demonstrating comparable reductions in inflammation upon exposure to MWCNTs in mice with the deletion of NF-κB (P50-/-). These results indicate the utility of celastrol as a promising pharmacological agent for preventing MWCNT-induced lung tissue inflammation.

Dibutyl phthalate adsorbed on multi-walled carbon nanotubes can aggravate liver injury in mice via the Jak2/STAT3 pathway

Phthalic acid esters (PAEs) and carbon nanotubes (CNTs) are common environmental pollutants and may degrade differently with different resulting biotoxicity, when present together. This study investigated the toxicological effects of singular or combined exposure to dibutyl phthalate (DBP) and multi-walled carbon nanotubes (MWCNTs) in KM mice. Results indicated that combined exposure led to slower weight gain and an increased leukocyte count in the blood, as well as liver tissue lesions and downregulation of organ coefficients. Additionally, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were elevated in the liver, and glucose, pyruvate, triglyceride (TG), and total cholesterol (T-CHO) were significantly reduced, suggesting compromised liver function. Furthermore, mRNA levels of genes related to hepatic glucose and lipid metabolism were significantly altered. These findings suggest that combined exposure to DBP and MWCNTs can have severe impacts on liver function in mice, highlighting the importance of considering interactions between multiple contaminants in environmental risk assessments.

In Vitro Cell Transformation Assays: A Valuable Approach for Carcinogenic Potentiality Assessment of Nanomaterials

This review explores the application of in vitro cell transformation assays (CTAs) as a screening platform to assess the carcinogenic potential of nanomaterials (NMs) resulting from continuously growing industrial production and use. The widespread application of NMs in various fields has raised concerns about their potential adverse effects, necessitating safety evaluations, particularly in long-term continuous exposure scenarios. CTAs present a realistic screening platform for known and emerging NMs by examining their resemblance to the hallmark of malignancy, including high proliferation rates, loss of contact inhibition, the gain of anchorage-independent growth, cellular invasion, dysregulation of the cell cycle, apoptosis resistance, and ability to form tumors in experimental animals. Through the deliberate transformation of cells via chronic NM exposure, researchers can investigate the tumorigenic properties of NMs and the underlying mechanisms of cancer development. This article examines NM-induced cell transformation studies, focusing on identifying existing knowledge gaps. Specifically, it explores the physicochemical properties of NMs, experimental models, assays, dose and time requirements for cell transformation, and the underlying mechanisms of malignancy. Our review aims to advance understanding in this field and identify areas for further investigation.

Needlelike, short and thin multi-walled carbon nanotubes: comparison of effects on wild type and p53+/- rat lungs

Carbon nanotubes (CNTs) are nanomaterials presenting an occupational inhalation risk during production or handling. The International Agency for Research on Cancer classified one CNT, Mitsui-7 (MWNT-7), as 'possibly carcinogenic to humans'. In recognition of their similarities, a proposal has been submitted to the risk assessment committee of ECHA to classify all fibers with 'Fibre Paradigm' (FP)-compatible dimensions as carcinogenic. However, there is a lack of clarity surrounding the toxicity of fibers that do not fit the FP criteria. In this study, we compared the effects of the FP-compatible Mitsui-7, to those of NM-403, a CNT that is too short and thin to fit the paradigm. Female Sprague Dawley rats deficient for p53 (GMO) and wild type (WT) rats were exposed to the two CNTs (0.25 mg/rat/week) by intratracheal instillation. Animals (GMO and WT) were exposed weekly for four consecutive weeks and were sacrificed 3 days or 8 months after the last instillation. Exposure to both CNTs induced acute lung inflammation. However, persistent inflammation at 8 months was only observed in the lungs of rats exposed to NM-403. In addition to the persistent inflammation, NM-403 stimulated hyperplasic changes in rat lungs, and no adenomas or carcinomas were detected. The degree and extent of hyperplasia was significantly more pronounced in GMO rats. These results suggest that CNT not meeting the FP criteria can cause persistent inflammation and hyperplasia. Consequently, their health effects should be carefully assessed.

Celastrol alleviates oxidative stress induced by multi-walled carbon nanotubes through the Keap1/Nrf2/HO-1 signaling pathway

Multi-walled carbon nanotubes (MWCNTs) mainly induce oxidative stress through the overproduction of reactive oxygen species (ROS), which can lead to cytotoxicity. Celastrol, a plant-derived compound, can exert antioxidant effects by reducing ROS production. Our results indicated that exposure to MWCNTs decreased cell viability and increased ROS production. Nrf2 knockdown (kd) led to increased ROS production and enhanced MWCNT-induced cytotoxicity. Keap1-kd led to decreased ROS production and attenuated cytotoxicity. Treatment with celastrol significantly decreased ROS production and promoted Keap1 protein degradation through the lysosomal pathway, thereby enhancing the translocation of Nrf2 from the cytoplasm to the nucleus and increasing HO-1 expression. The in vivo results showed that celastrol could alleviate the inflammatory damage of lung tissues, increase the levels of the antioxidants, GSH and SOD, as well as promote the expression of the antioxidant protein, HO-1 in MWCNT-treated mice. Celastrol can alleviate MWCNT-induced oxidative stress through the Keap1/Nrf2/HO-1 signaling pathway.

Vascular toxicity of multi-walled carbon nanotubes targeting vascular endothelial growth factor

Multiwalled carbon nanotubes (MWCNTs) are currently widely used and are expected to be used as drug carriers and contrast agents in clinical practice. Previous studies mainly focused on their lung toxicity; therefore, their effects on the vascular endothelium are unclear. In this study, a human angiogenesis array was used to determine the effect of MWCNTs on the expression profile of angiogenic factors in endothelial cells and to clarify the role of vascular endothelial growth factor (VEGF) in MWCNT-induced endothelial cell injury at the cellular and animal levels. The results indicated that MWCNTs (20-30 nm and 30-50 nm) could enter endothelial cells and disrupt human umbilical vein endothelial cell (HUVECs) activity in a concentration-dependent manner. MWCNTs disrupted the tube formation ability and cell migration function of HUVECs. The results from a Matrigel Plug experiment in mice showed that angiogenesis in the MWCNT experimental group was significantly reduced. The results of a protein chip analysis indicated that VEGF expression in the MWCNT treatment group was decreased, a finding that was validated by ELISA results. The protein expression levels of AKT and eNOS in the MWCNT treatment group were significantly decreased; the administration of recombinant VEGF significantly alleviated the migration ability and tube formation ability of endothelial cells injured by MWCNTs, upregulated the protein expression of AKT and eNOS, and increased the number of neovascularization in mice in the MWCNT treatment group. This study demonstrated that MWCNTs affect angiogenesis via the VEGF-Akt-eNOS axis which can be rescued by VEGF endothelial treatment.

Mannose Receptor-Mediated Carbon Nanotubes as an Antigen Delivery System to Enhance Immune Response Both In Vitro and In Vivo

Carbon nanotubes (CNTs) are carbon allotropes consisting of one, two, or more concentric rolled graphene layers. These can intrinsically regulate immunity by activating the innate immune system. Mannose receptors (MR), a subgroup of the C-type lectin superfamily, are abundantly expressed on macrophages and dendritic cells. These play a crucial role in identifying pathogens, presenting antigens, and maintaining internal environmental stability. Utilizing the specific recognition between mannose and antigen-presenting cells (APC) surface mannose receptors, the antigen-carrying capacity of mannose-modified CNTs can be improved. Accordingly, here, we synthesized the mannose-modified carbon nanotubes (M-MWCNT) and evaluated them as an antigen delivery system through a series of in vitro and in vivo experiments. In vitro, M-MWCNT carrying large amounts of OVA were rapidly phagocytized by macrophages and promoted macrophage proliferation to facilitate cytokines (IL-1β, IL-6) secretion. In vivo, in mice, M-MWCNT induced the maturation of dendritic cells and increased the levels of antigen-specific antibodies (IgG, IgG1, IgG2a, IgG2b), and cytokines (IFN-γ, IL-6). Taken together, M-MWCNT could induce both humoral and cellular immune responses and thereby can be utilized as an efficient antigen-targeted delivery system.

Flavonoids against non-physiologic inflammation attributed to cancer initiation, development, and progression—3PM pathways

Inflammation is an essential pillar of the immune defense. On the other hand, chronic inflammation is considered a hallmark of cancer initiation and progression. Chronic inflammation demonstrates a potential to induce complex changes at molecular, cellular, and organ levels including but not restricted to the stagnation and impairment of healing processes, uncontrolled production of aggressive ROS/RNS, triggered DNA mutations and damage, compromised efficacy of the DNA repair machinery, significantly upregulated cytokine/chemokine release and associated patho-physiologic protein synthesis, activated signaling pathways involved in carcinogenesis and tumor progression, abnormal tissue remodeling, and created pre-metastatic niches, among others. The anti-inflammatory activities of flavonoids demonstrate clinically relevant potential as preventive and therapeutic agents to improve individual outcomes in diseases linked to the low-grade systemic and chronic inflammation, including cancers. To this end, flavonoids are potent modulators of pro-inflammatory gene expression being, therefore, of great interest as agents selectively suppressing molecular targets within pro-inflammatory pathways. This paper provides in-depth analysis of anti-inflammatory properties of flavonoids, highlights corresponding mechanisms and targeted molecular pathways, and proposes potential treatment models for multi-level cancer prevention in the framework of predictive, preventive, and personalized medicine (PPPM / 3PM). To this end, individualized profiling and patient stratification are essential for implementing targeted anti-inflammatory approaches. Most prominent examples are presented for the proposed application of flavonoid-conducted anti-inflammatory treatments in overall cancer management.

Four Immune-Related Genes (FN1, UGCG, CHPF2 and THBS2) as Potential Diagnostic and Prognostic Biomarkers for Carbon Nanotube-Induced Mesothelioma

Background

Malignant pleural mesothelioma (MPM), a highly aggressive cancer, was mainly attributed to asbestos exposure. Carbon nanotubes (CNTs) share similar negative features to asbestos, provoking concerns about their contribution to MPM. This study was used to identify genes associated with CNT-induced MPM.

Methods

Microarray datasets were available in the Gene Expression Omnibus database. The limma method was used to identify differentially expressed genes (DEGs) in CNT-exposed MeT5A cells (GSE48855) or mice (GSE51636). Weighted correlation network analysis (WGCNA) and protein–protein interaction (PPI) network construction were conducted to screen hub DEGs. The mRNA expression levels of hub DEGs were validated on MPM samples of GSE51024, GSE2549 and GSE42977 datasets, and their diagnostic efficacy was determined by receiver operating characteristic curve analysis. The prognostic values of hub DEGs were assessed using online tools based on The Cancer Genome Atlas data. Their functions were annotated by Database for Annotation, Visualization and Integrated Discovery (DAVID) enrichment and correlation with immune cells and markers.

Results

WGCNA identified that two modules were associated with disease status. Thirty-one common DEGs in the GSE48855 and GSE51636 datasets were overlapped with the genes in these two modules. Twenty of them had a high degree centrality (≥4) in the PPI network. Four DEGs (FN1, fibronectin 1; UGCG, UDP-glucose ceramide glucosyltransferase; CHPF2, chondroitin polymerizing factor 2; and THBS2, thrombospondin 2) could predict the overall survival, and they were confirmed to be upregulated in MPM samples compared with controls. Also, they could effectively predict the MPM risk, with an overall accuracy of >0.9. DAVID analysis revealed FN1, CHPF2 and THBS2 functioned in cell-ECM interactions; UGCG influenced glycosphingolipid metabolism. All genes were positively associated with infiltrating levels of immune cells (macrophages or dendritic cells) and the expression of the dendritic cell marker (NRP1, neuropilin 1).

Conclusion

These four immune-related genes represent potential biomarkers for monitoring CNT-induced MPM and predicting the prognosis.

Reactive oxygen species production, genotoxicity and telomere length in FE1-Muta™Mouse lung epithelial cells exposed to carbon nanotubes

Carbon nanotubes (CNTs) are fiber-like nanomaterials, which are used in various applications with possible exposure to humans. The genotoxicity and carcinogenic potential of CNTs remain to be fully understood. This study assessed the genotoxicity of three different multi-walled carbon nanotubes (MWCNTs) (MWCNT-7, NM-401 and NM-403) and one single-walled carbon nanotube (SWCNT) (NM-411) in FE1-Muta™Mouse lung epithelial (MML) cells using the alkaline comet assay. With the 2',7'-dichlorodihydrofluorescein diacetate fluorescent probe, we assessed the effect of CNT-exposure on the intracellular production of reactive oxygen species (ROS). We measured the effect of a 10-week CNT exposure on telomere length using quantitative PCR. Two of the included MWCNTs (NM-401 and MWCNT-7) and the SWCNT (NM-411) caused a significant increase in the level of DNA damage at concentrations up to 40 µg/ml (all concentrations pooled, p < 0.05), but no concentration-response relationships were found. All of the CNTs caused an increase in intracellular ROS production compared to unexposed cells (p_trend < 0.05). Results from the long-term exposure showed longer telomere length in cells exposed to MWCNTs compared to unexposed cells (p < 0.01). In conclusion, our results indicated that the included CNTs cause ROS production and DNA strand breaks in FE1-MML cells. Moreover, the MWCNTs, but not the SWCNT, had an impact on telomere length in a long-term exposure scenario.

Identification of four methylation-driven genes as candidate biomarkers for monitoring single-walled carbon nanotube-induced malignant transformation of the lung

Long-term exposure to carbon nanotubes (CNTs) has been reported to induce malignant transformation. This study aimed to screen candidate biomarkers for monitoring occupational workers to prevent the development of lung cancer. mRNA (GSE56104) and methylation (GSE153246) profiles of lung epithelial BEAS-2B cells exposed to malignant transformation dose of single-walled CNTs or control medium were downloaded from Gene Expression Omnibus database. A total of 1513 differentially expressed genes (DEGs) and 912 differentially methylated genes (DMGs) were identified using LIMMA method. The weighted correlation network analysis identified blue and turquoise modules were associated with malignant transformation of BEAS-2B cells, 124 DMGs of which were overlapped with DEGs. The mRNA and methylation levels of four methylation-driven DEGs were validated in both lung adenocarcinoma (LUAD) and squamous cell carcinomas (LUSC) of The Cancer Genome Atlas dataset and they were associated with overall survival of LUAD patients. Downregulation of PXMP4 and MCOLN2, while upregulation of MET was confirmed in both LUSC and LUAD via Human Protein Atlas analysis. PXMP4 and MET protein levels were also supported in the proteomic analysis of LUAD. Receiver operating characteristic (ROC) curve analysis showed the combination of four genes may be the optimal biomarker for predicting lung cancer, with the area under ROC curve >0.9. Function analysis revealed BARX2 may interact with CCND1 to regulate cell cycle; MET and PXMP4/MCOLN2 may positively correlate with CCR5/IL-6 or GATA3/HLA-DPB1/HLA-DPA1 to involve immune regulation. In conclusion, these four methylation-driven genes may be candidate prognostic and diagnostic biomarkers for single-walled CNT-related lung cancer.