Myocardial toxicity induced by silica nanoparticles in a transcriptome profile

Prospects and hazards of silica nanoparticles: Biological impacts and implicated mechanisms

With the thrive of nanotechnology, silica nanoparticles (SiNPs) have been extensively adopted in the agriculture, food, cosmetic, and even biomedical industries. Due to the mass production and use, SiNPs inevitably entered the environment, resulting in ecological toxicity and even posing a threat to human health. Although considerable investigations have been conducted to assess the toxicity of SiNPs, the correlation between SiNPs exposure and consequent health risks remains ambiguous. Since the biological impacts of SiNPs can differ from their design and application, the toxicity assessment for SiNPs may be extremely difficult. This review discussed the application of SiNPs in different fields, especially their biomedical use, and documented their potential release pathways into the environment. Meanwhile, the current process of assessing SiNPs-related toxicity on various model organisms and cell lines was also detailed, thus estimating the health threats posed by SiNPs exposure. Finally, the potential toxic mechanisms of SiNPs were also elaborated based on results obtained from both in vivo and in vitro trials. This review generally summarizes the biological effects of SiNPs, which will build up a comprehensive perspective of the application and toxicity of SiNPs.

Silica nanoparticles induce pulmonary damage in rats via VEGFC/D-VEGFR3 signaling-mediated lymphangiogenesis and remodeling

Silica nanoparticles (SiNPs) are widely used as drug carriers for improving drug delivery and retention. The lungs are highly sensitive to the toxicity of SiNPs entering the respiratory tract. Furthermore, pulmonary lymphangiogenesis, which is the growth of lymphatic vessels observed during multiple pulmonary diseases, plays a vital role in promoting the lymphatic transport of silica in the lungs. However, more research is required on the effects of SiNPs on pulmonary lymphangiogenesis. We investigated the effect of SiNP-induced pulmonary toxicity on lymphatic vessel formation in rats and evaluated the toxicity and possible molecular mechanisms of 20-nm SiNPs. Saline containing 3.0, 6.0, and 12.0mg/kg of SiNPs was instilled intrathecally into female Wistar rats once a day for five days, then sacrificed on day seven. Lung histopathology, pulmonary permeability, pulmonary lymphatic vessel density changes, and the ultrastructure of the lymph trunk were investigated using light microscopy, spectrophotometry, immunofluorescence, and transmission electron microscopy. CD45 expression in lung tissues was determined using immunohistochemical staining, and protein expression in the lung and lymph trunk was quantified using western blotting. We observed increased pulmonary inflammation and permeability, lymphatic endothelial cell damage, pulmonary lymphangiogenesis, and remodeling with increasing SiNP concentration. Moreover, SiNPs activated the VEGFC/D-VEGFR3 signaling pathway in the lung and lymphatic vessel tissues. SiNPs caused pulmonary damage, increased permeability and resulted in inflammation-associated lymphangiogenesis and remodeling by activating VEGFC/D-VEGFR3 signaling. Our findings provide evidence for SiNP-induced pulmonary damage and a new perspective for the prevention and treatment of occupational exposure to SiNPs. DATA AVAILABILITY: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

The effects of short-term dietary exposure to SiO2 nanoparticle on the domesticated lepidopteran insect model silkworm (Bombyx mori): Evidence from the perspective of multi-omics

Silicon dioxide nanoparticles (nSiO₂) are one of the widely utilized nanoparticle (NPSs) materials, and exposure to nSiO₂ is ubiquitous. With the increasing commercialization of nSiO₂, the potential risk of nSiO₂ release to the health and the ecological environment have been attracted more attention. In this study, the domesticated lepidopteran insect model silkworm (Bombyx mori) was utilized to evaluate the biological effects of dietary exposure to nSiO₂. Histological investigations showed that nSiO₂ exposure resulted in midgut tissue injury in a dose-dependent manner. Larval body mass and cocoon production were reduced by nSiO₂ exposure. ROS burst was not triggered, and the activities of antioxidant enzymes were induced in the midgut of silkworm exposure to nSiO₂. RNA-sequencing revealed that the differentially expressed genes induced by nSiO₂ exposure were predominantly enriched into xenobiotics biodegradation and metabolism, lipid, and amino acid metabolism pathways. 16 S rDNA sequencing revealed that nSiO₂ exposure altered the microbial diversity in the gut of the silkworm. Metabolomics analysis showed that the combined uni- and multivariate analysis identified 28 significant differential metabolites from the OPLS-DA model. These significant differential metabolites were predominantly enriched into the metabolic pathways, including purine metabolism and tyrosine metabolism and so. Spearman correlation analysis and the Sankey diagram established the relationship between microbe and metabolites, and some genera may play crucial and pleiotropic functions in the interaction between microbiome and host. These findings indicated that nSiO₂ exposure could impact the dysregulation of genes related to xenobiotics metabolism, gut dysbiosis, and metabolic pathways and provided a valuable reference for assessing nSiO₂ toxicity from a multi-dimensional perspective.

Proteomic profiling reveals dysregulated mitochondrial complex subunits responsible for myocardial toxicity induced by SiNPs

The relationship between environmental exposure to silica nanoparticles (SiNPs) and adverse cardiac outcomes has received more attention. Our recent work has revealed a size-dependent impact of the intratracheal instilled SiNPs on cardiac health of ApoE^-/- mice using nanoscale SiNPs-60 and submicro-sized SiNPs-300, but the underlying mechanism of action still remains unclear. Hence, we identified proteins and protein networks perturbed by SiNPs in myocardial tissues of ApoE^-/- mice by using LC-MS/MS-based quantitative proteomics. A set of 435 differentially expressed proteins (DEPs) were screened in response to SiNPs, which mainly enriched in the mitochondria and functioned in cell metabolism, biosynthesis and signal transduction. KEGG analysis showed that DEPs were significantly associated with oxidative phosphorylation and cardiomyopathy. The protein-protein interaction (PPI) network revealed 9 DEPs (e.g., Ndufs1, Ndufv1, Cox4i1) as potential biomarkers of SiNPs-induced myocardial toxicity. Of note, all the 9 candidate proteins were subunits of mitochondria respiratory chain complex, and their expressions were dependent on particle size, which were remarkably down-regulated by SiNPs-60 but not by SiNPs-300. More importantly, the correlation analysis verified the 9 dysregulated mitochondria complex protein subunits strongly correlated to the biochemical and functional indexes of cardiac injury in response to SiNPs. In conclusion, our study firstly provided significant proteomic insights into the potential molecular mechanisms underlying SiNPs-elicited cardiotoxicity, with the dysregulated mitochondrial complex subunits as core regulatory molecules. Overall, our study would provide the scientific basis for the molecular actions and mechanisms of toxicity induced by SiNPs.

Silica nanoparticles aggravated the metabolic associated fatty liver disease through disturbed amino acid and lipid metabolisms-mediated oxidative stress

The metabolic associated fatty liver disease (MAFLD) is a public health challenge, leading to a global increase in chronic liver disease. The respiratory exposure of silica nanoparticles (SiNPs) has revealed to induce hepatotoxicity. However, its role in the pathogenesis and progression of MAFLD was severely under-studied. In this context, the hepatic impacts of SiNPs were investigated in vivo and in vitro through using ApoE^-/- mice and free fatty acid (FFA)-treated L02 hepatocytes. Histopathological examinations and biochemical analysis showed SiNPs exposure via intratracheal instillation aggravated hepatic steatosis, lipid vacuolation, inflammatory infiltration and even collagen deposition in ApoE^-/- mice, companied with increased hepatic ALT, AST and LDH levels. The enhanced fatty acid synthesis and inhibited fatty acid β-oxidation and lipid efflux may account for the increased hepatic TC/TG by SiNPs. Consistently, SiNPs induced lipid deposition and elevated TC in FFA-treated L02 cells. Further, the activation of hepatic oxidative stress was detected in vivo and in vitro, as evidenced by ROS accumulation, elevated MDA, declined GSH/GSSG and down-regulated Nrf2 signaling. Endoplasmic reticulum (ER) stress was also triggered in response to SiNPs-induced lipid accumulation, as reflecting by the remarkable ER expansion and increased BIP expression. More importantly, an UPLC-MS-based metabolomics analysis revealed that SiNPs disturbed the hepatic metabolic profile in ApoE^-/- mice, prominently on amino acids and lipid metabolisms. In particular, the identified differential metabolites were strongly correlated to the activation of oxidative stress and ensuing hepatic TC/TG accumulation and liver injuries, contributing to the progression of liver diseases. Taken together, our study showed SiNPs promoted hepatic steatosis and liver damage, resulting in the aggravation of MAFLD progression. More importantly, the disturbed amino acids and lipid metabolisms-mediated oxidative stress was a key contributor to this phenomenon from a metabolic perspective.

Silica nanoparticles perturbed mitochondrial dynamics and induced myocardial apoptosis via PKA-DRP1-mitochondrial fission signaling

Silica nanoparticles (SiNPs) are among the most abundantly produced nanosized particles in the global market, and their potential toxicity has aroused a great concern. Increasing epidemiological investigations and experimental evidence revealed the threaten of SiNPs exposure to cardiovascular system. The myocardial toxicity caused by SiNPs was gradually demonstrated, nevertheless, the underlying mechanisms remain unclear. In view of mitochondria serving as the centrality in the prominent of cardiovascular disease, we investigated the role of mitochondria and related mechanisms in SiNPs-induced adverse effects on cardiomyocytes. As a result, SiNPs were found in cytoplasm, accompanied with morphological alterations in mitochondria, such as cristae fracture or disappearance, vacuolation. The induction of mitochondrial dysfunction by SiNPs was confirmed, as indicated by the excessive reactive oxygen species (ROS) formation, and blockage of cellular respiratory and ATP production. Concomitantly, SiNPs activated mitochondria-mediated apoptotic signaling in view of the up-regulated BAX, increased Caspase-9 cleavage and declined Bcl-2, ultimately resulting in myocardial apoptosis. It was noteworthy that SiNPs disturbed mitochondrial dynamics toward fission phenotype, which was supported by the dysregulated fission/fusion regulators. Especially, DRP1 and its phosphorylated level at s616 (p-DRP1^s616) were up-regulated, whilst its phosphorylated level at s637 (p-DRP1^s637) and PKA phosphorylation were down-regulated in SiNPs-treated cardiomyocytes in a dose-dependent manner. More importantly, the mechanistic investigations revealed PKA-DRP1-mediated mitochondrial fission was responsible for SiNPs-induced cardiomyocyte apoptosis through the mitochondria-mediated apoptotic way. This study firstly demonstrated the disturbance of mitochondrial dynamics played a crucial role in cardiomyocyte apoptosis caused by SiNPs, attributing to PKA-DRP1-mitochondrial fission signaling.

Silica nanoparticles induce cardiac injury and dysfunction via ROS/Ca2+/CaMKII signaling

Interest is growing to better comprehend the interaction of silica nanoparticles (SiNPs) with the cardiovascular system. In particular, the extremely small size, relatively large surface area and associated unique properties may greatly enhance its toxic potentials compared to larger-sized counterparts. Nevertheless, the underlying mechanisms still need to be evaluated. In this context, the cardiotoxicity of nano-scale (Si-60; particle diameter about 60 nm) and submicro-scale silica particles (Si-300; 300 nm) were examined in ApoE^-/- mice via intratracheal instillation, 6.0 mg/kg·bw, once per week for 12 times. The echocardiography showed that the sub-chronic exposure of Si-60 declined cardiac output (CO) and stroke volume (SV), shorten LVIDd and LVIDs, and thickened LVAWs of ApoE^-/- mice in compared to the control and Si-300 groups. Histological investigations manifested Si-60 enhanced inflammatory infiltration, myocardial fiber arrangement disorder, hypertrophy and fibrosis in the cardiac tissue, as well as mitochondrial ultrastructural injury. Accordingly, the serum cTnT, cTnI and ANP were significantly elevated by Si-60, as well as cardiac ANP content. In particular, Si-60 greatly increased cardiac ROS, Ca²⁺ levels and CaMKII activation in comparison with Si-300. Further, in vitro investigations revealed silica particles induced a dose- and size-dependent activation of oxidative stress, mitochondrial membrane permeabilization, intracellular Ca²⁺ overload, CaMKII signaling activation and ensuing myocardial apoptosis in human cardiomyocytes (AC16). Mechanistic analyses revealed SiNPs induced myocardial apoptosis via ROS/Ca²⁺/CaMKII signaling, which may contribute to the abnormalities in cardiac structure and function in vivo. In summary, our research revealed SiNPs caused myocardial impairments, dysfunction and even structural remodeling via ROS/Ca²⁺/CaMKII signaling. Of note, a size-dependent myocardial toxicity was noticed, that is, Si-60 greater than Si-300.