CdTe and CdTe@ZnS quantum dots induce IL-1ß-mediated inflammation and pyroptosis in microglia

Application of quantum dots in brain diseases and their neurotoxic mechanism

The early-stage diagnosis and therapy of brain diseases pose a persistent challenge in the field of biomedicine. Quantum dots (QDs), nano-luminescent materials known for their small size and fluorescence imaging capabilities, present promising capabilities for diagnosing, monitoring, and treating brain diseases. Although some investigations about QDs have been conducted in clinical trials, the concerns about the toxicity of QDs have continued. In addition, the lack of effective toxicity evaluation methods and systems and the difference between in vivo and in vitro toxicity evaluation hinder QDs application. The primary objective of this paper is to introduce the neurotoxic effects and mechanisms attributable to QDs. First, we elucidate the utilization of QDs in brain disorders. Second, we sketch out three pathways through which QDs traverse into brain tissue. Ultimately, expound upon the adverse consequences of QDs on the brain and the mechanism of neurotoxicity in depth. Finally, we provide a comprehensive summary and outlook on the potential development of quantum dots in neurotoxicity and the difficulties to be overcome.

One-Pot Synthesis of CdTe/ZnS Quantum Dots and their Physico-Chemical Characterization

A known property of quantum dots (QDs) is their characteristic luminescence, which would make it possible to detect different types of cancers after being functionalized with some type of biological molecule. For this reason, in the present investigation a methodological analysis of the physicochemical characteristics of the CdTe/ZnS core/shell QDs was carried out, using techniques such as Optical Absorbance Spectroscopy (UV-Vis), Molecular Fluorescence, Fourier Transform Infrared Spectroscopy (FT-IR), Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Zeta Potential that allowed to verify the photoluminescent effectiveness of these semiconductor nanocrystals as an alternative to conventional techniques currently used for the detection of specific cancers smaller than 1 cm. The study consisted of theoretically determining the bandgap energy, the size of the nanocrystals and the molar absorptivity from the wavelength value for the maximum intensity of the excitonic peak. It was also possible to verify the maximum intensity for each sample and thus evaluate its photoluminescent response, as well as it was possible to determine the charge distribution, the hydrodynamic size and the surface composition of each quantum dot. The results obtained correspond to what has been reported in the literature, which makes them good candidates for the detection of cancer in precancerous stages.

Exposure of quantum dots in the nervous system: Central nervous system risks and the blood-brain barrier interface

Quantum dots currently possess significant importance in the field of biomedical science. Upon introduction into the body, quantum dots exhibit a tendency to accumulate in diverse tissues including the central nervous system (CNS). Consequently, it becomes imperative to devote specific attention to their potential toxic effects. Moreover, the preservation of optimal CNS function relies heavily on blood-brain barrier (BBB) integrity, thereby necessitating its prioritization in neurotoxicological investigations. A more comprehensive understanding of the BBB and CNS characteristics, along with the underlying mechanisms that may contribute to neurotoxicity, will greatly aid researchers in the development of effective design strategies. This article offers an in-depth look at the methods used to reduce the harmful effects of quantum dots on the nervous system, alongside the progression of effective treatments for brain-related conditions. The focal point of this discussion is the BBB and its intricate association with the CNS and neurotoxicology. The discourse commences by recent advancements in the medical application of quantum dots are examined. Subsequently, elucidating the mechanisms through which quantum dots infiltrate the human body and traverse into the brain. Additionally, the discourse delves into the factors that facilitate the passage of quantum dots across the BBB, primarily encompassing the physicochemical properties of quantum dots and the BBB's inherent capacity for self-permeability alteration. Furthermore, a concluding summary is presented, emphasizing existing research deficiencies and identifying promising avenues for further investigation within this field.

ROS-mediated NRF2/p-ERK1/2 signaling-involved mitophagy contributes to macrophages activation induced by CdTe quantum dots

Cadmium telluride (CdTe) quantum dots (QDs) have garnered significant attention for tumor imaging due to their exceptional properties. However, there remains a need for further investigation into their potential toxicity mechanisms and corresponding enhancements. Herein, CdTe QDs were observed to accumulate in mouse liver, leading to a remarkable overproduction of IL-1β and IL-6. Additionally, there was evidence of macrophage infiltration and activation following exposure to 12.5 μmol/kg body weight of QDs. To elucidate the underlying mechanism of macrophage activation, CdTe QDs functionalized with 3-mercaptopropionic acid (MPA) were utilized. In vitro experiments revealed that 1.0 μM MPA-CdTe QDs activated PINK1-dependent mitophagy in RAW264.7 macrophages. Critically, the autophagic flux remained unimpeded, as demonstrated by the absence of p62 accumulation, LC3 turnover assay results, and successful fusion of autophagosomes with lysosomes. Mechanically, QDs increased reactive oxygen species (ROS) and mitoROS by damaging both mitochondria and lysosomes. ROS, in turn, inhibited NRF2, resulting in the phosphorylation of ERK1/2 and subsequent activation of mitophagy. Notably, 1.0 μM QDs disrupted lysosomes but autophagic flux was not impaired. Eventually, the involvement of the ROS-NRF2-ERK1/2 pathway-mediated mitophagy in the increase of IL-1β and IL-6 in macrophages was confirmed using Trolox, MitoTEMPO, ML385, specific siRNAs, and lentivirus-based interventions. This study innovatively revealed the pro-inflammatory rather than anti-inflammatory role of mitophagy in nanotoxicology, shedding new light on the mechanisms of mitochondrial disorders induced by QDs and identifying several molecular targets to comprehend the toxicological mechanisms of CdTe QDs.

Oxidative stress-induced neurotoxicity of quantum dots and influencing factors

Quantum dots (QDs) have significant potential for treating and diagnosing CNS diseases. Meanwhile, the neurotoxicity of QDs has garnered attention. In this review, we focus on elucidating the mechanisms and consequences of CNS oxidative stress induced by QDs. First, we discussed the pathway of QDs transit into the brain. We then elucidate the relationship between QDs and oxidative stress from in vivo and in vitro studies. Furthermore, the main reasons and adverse outcomes of QDs leading to oxidative stress are discussed. In addition, the primary factors that may affect the neurotoxicity of QDs are analyzed. Finally, we propose potential strategies for mitigating QDs neurotoxicity and outline future perspectives for their development.

Nanoparticles and neurodegeneration: Insights on multiple pathways of programmed cell death regulated by nanoparticles

Currently, nanoparticles (NPs) are extensively applied in the diagnosis and treatment of neurodegenerative diseases (NDs). With the rapid development and increasing exposure to the public, the potential neurotoxicity associated with NDs caused by NPs has attracted the researchers' attentions but their biosafety assessments are still far behind relevant application studies. Based on recent research, this review aims to conduct a comprehensive and systematic analysis of neurotoxicity induced by NPs. The 191 studies selected according to inclusion and exclusion criteria were imported into the software, and the co-citations and keywords of the included literatures were analyzed to find the breakthrough point of previous studies. According to the available studies, the routes of NPs entering into the normal and injured brain were various, and then to be distributed and accumulated in living bodies. When analyzing the adverse effects induced by NPs, we focused on multiple programmed cell deaths (PCDs), especially ferroptosis triggered by NPs and their tight connection and crosstalk that have been found playing critical roles in the pathogenesis of NDs and their underlying toxic mechanisms. The activation of multiple PCD pathways by NPs provides a scientific basis for the occurrence and development of NDs. Furthermore, the adoption of new methodologies for evaluating the biosafety of NPs would benefit the next generation risk assessment (NGRA) of NPs and their toxic interventions. This would help ensure their safe application and sustainable development in the field of medical neurobiology.

Nanomaterial-induced pyroptosis: a cell type-specific perspective

This review presents the advancements in nanomaterial (NM)-induced pyroptosis in specific types of cells. We elucidate the relevance of pyroptosis and delineate its mechanisms and classifications. We also retrospectively analyze pyroptosis induced by various NMs in a broad spectrum of non-tumorous cellular environments to highlight the multifunctionality of NMs in modulating cell death pathways. We identify key knowledge gaps in current research and propose potential areas for future exploration. This review emphasizes the need to focus on less-studied areas, including the pathways and mechanisms of NM-triggered pyroptosis in non-tumor-specific cell types, the interplay between biological and environmental factors, and the interactions between NMs and cells. This review aims to encourage further investigations into the complex interplay between NMs and pyroptosis, thereby providing a basis for developing safer and more effective nanomedical therapeutic applications.

Protein corona exacerbated inflammatory response in macrophages elicited by CdTe quantum dots

Nano-bio interface is significant concern in nanomedicine. When nanoparticles (NPs) come into contact with cells, they form complexes with proteins known as protein corona (PC). Cadmium telluride quantum dots (CdTe QDs) have been applied as bioimaging probes and for macrophage theragnostic. However, the impact of protein corona on the behavior of CdTe QDs is not well understood. Macrophages play a crucial role in defending against NPs. In this study, RAW264.7 cells were used to investigated the inflammatory response in macrophages when exposed to CdTe QDs before and after PC formation in fetal bovine serum. The results indicated that protein corona polarized more macrophages towards M1 phenotype. Transcriptomics analysis revealed that PC-CdTe QDs altered a greater number of differentially expressed genes (DEGs) compared to CdTe QDs (177 and 398) at 1.0 μM in macrophages. The DEGs affected by PC-CdTe QDs contained several personalized inflammatory cytokines. The enriched pathways after PC formation included Cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway, and TNF signaling pathway, etc. Furthermore, PC specifically exacerbated the overexpression of CCL2 and IL-1β proteins. Importantly, PC altered the mechanism of CdTe QD-induced pyroptosis, shifting it from activating NLRC4 to both NLRP1 and NLRP3 inflammasomes, and from cleaving GSDMD and GSDMB to GSDMB alone. Overall, protein corona exacerbated the inflammatory response induced by CdTe QDs in macrophages. This study provides valuable insight into the pro-inflammatory effect of protein corona on CdTe QDs, with implications for their use in bioimaging or macrophage theragnostic by either exploiting or eliminating this biological interface effect.

An update on the biological effects of quantum dots: From environmental fate to risk assessment based on multiple biological models

Quantum dots (QDs) are zero-dimension nanomaterials with excellent physical and chemical properties, which have been widely used in environmental science and biomedicine. Therefore, QDs are potential to cause toxicity to the environment and enter organisms through migration and bioenrichment effects. This review aims to provide a comprehensive and systematic analysis on the adverse effects of QDs in different organisms based on recently available data. Following PRISMA guidelines, this study searched PubMed database according to the pre-set keywords, and included 206 studies according to the inclusion and elimination criteria. CiteSpace software was firstly used to analyze the keywords of included literatures, search for breaking points of former studies, and summarize the classification, characterization and dosage of QDs. The environment fate of QDs in the ecosystems were then analyzed, followed with comprehensively summarized toxicity outcomes at individual, system, cell, subcellular and molecular levels. After migration and degradation in the environment, aquatic plants, bacteria, fungi as well as invertebrates and vertebrates have been found to be suffered from toxic effects caused by QDs. Aside from systemic effects, toxicity of intrinsic QDs targeting to specific organs, including respiratory system, cardiovascular system, hepatorenal system, nervous system and immune system were confirmed in multiple animal models. Moreover, QDs could be taken up by cells and disturb the organelles, which resulted in cellular inflammation and cell death, including autophagy, apoptosis, necrosis, pyroptosis and ferroptosis. Recently, several innovative technologies, like organoids have been applied in the risk assessment of QDs to promote the surgical interventions of preventing QDs' toxicity. This review not only aimed at updating the research progress on the biological effects of QDs from environmental fate to risk assessment, but also overcame the limitations of available reviews on basic toxicity of nanomaterials by interdisciplinarity and provided new insights for better applications of QDs.

Assessing regulated cell death modalities as an efficient tool for in vitro nanotoxicity screening: a review

Nanomedicine is a fast-growing field of nanotechnology. One of the major obstacles for a wider use of nanomaterials for medical application is the lack of standardized toxicity screening protocols for assessing the safety of newly synthesized nanomaterials. In this review, we focus on less frequently studied nanomaterials-induced regulated cell death (RCD) modalities, including eryptosis, necroptosis, pyroptosis, and ferroptosis, as a tool for in vitro nanomaterials safety evaluation. We summarize the latest insights into the mechanisms that mediate these RCDs in response to nanomaterials exposure. Comprehensive data from reviewed studies suggest that ROS (reactive oxygen species) overproduction and ROS-mediated pathways play a central role in nanomaterials-induced RCDs activation. On the other hand, studies also suggest that individual properties of nanomaterials, including size, shape, or surface charge, could determine specific toxicity pathways with consequent RCD induction as well. We anticipate that the evaluation of RCDs can become one of the mechanism-based screening methods in nanotoxicology. In addition to the toxicity assessment, evaluation of necroptosis-, pyroptosis-, and ferroptosis-promoting capacity of nanomaterials could simultaneously provide useful information for specific medical applications as could be their anti-tumor potential. Moreover, a detailed understanding of molecular mechanisms driving nanomaterials-mediated induction of immunogenic RCDs will substantially aid novel anti-tumor nanodrugs development.

The DNA damage potential of quantum dots: Toxicity, mechanism and challenge

Quantum dots (QDs) are semiconductor nanoparticles (1-10 nm) with excellent optical and electrical properties. As QDs show great promise for applications in fields such as biomedicine, their biosafety is widely emphasized. Therefore, studies on the potential 'nanotoxicity' of QDs in genetic material are warranted. This review summarizes and discusses recent reports derived from different cell lines or animal models concerning the effects of QDs on genetic material. QDs could induce many types of genetic material damage, which subsequently triggers a series of cellular adverse outcomes, including apoptosis, cell cycle arrest and senescence. However, the individual biological and ecological significance of the genotoxicity of QDs is not yet clear. In terms of mechanisms of genotoxicity, QDs can damage DNA either through their own nanomorphology or through the released metal ions. It also includes the reactive oxygen species generation, inflammation and failure of DNA damage repair. Notably, apoptosis may lead to false positive results in genotoxicity tests. Finally, given the different uses of QDs and the interference of the physicochemical properties of QDs on the test method, genotoxicity testing of QDs should be different from traditional toxic compounds, which requires further research.

CdTe quantum dots trigger oxidative stress and endoplasmic reticulum stress-induced apoptosis and autophagy in rat Schwann cell line RSC96

In the current study, the cytotoxicity and mechanisms of cadmium telluride quantum dots (CdTe QDs) on RSC96 cells were evaluated by exposing different doses of CdTe QDs for 24 h. Two types of cell death, including apoptosis and autophagy, as well as two important organelles, mitochondria and endoplasmic reticulum, were focused after CdTe QDs exposure. The results showed that CdTe QDs induced apoptosis in RSC96 cells in a concentration-dependent manner; promoted the accumulation of intracellular reactive oxygen species; decreased the mitochondrial membrane potential; caused the release of cytochrome c; and also increased the expression of Bcl-2 associated X protein, caspase-3, and cytochrome c proteins and decreased the expression of Bcl-2 protein. Further results also confirmed that CdTe QDs could be internalized by RSC96 cells, and the exposure and internalization of CdTe QDs could induce excessive endoplasmic reticulum stress in the cells, and the expression levels of binding immunoglobulin protein, C/EBP homologous protein, and caspase12 proteins were increased in a concentration-dependent manner. Moreover, autophagy-related proteins LC3II, Beclin1, and P62 all increased after CdTe QDs exposure, suggesting that CdTe QDs exposure both promoted autophagosome formation and inhibited autophagosome degradation, and that CdTe QDs affected the autophagic flow in RSC96 cells. In conclusion, CdTe QDs are able to cause apoptosis and autophagy in RSC96 cells through mitochondrial and endoplasmic reticulum stress pathways, and the possible neurotoxicity of CdTe QDs should be further investigated.

Silica Nanoparticles Cause Activation of NLRP3 Inflammasome in-vitro Model-Using Microglia

INTRODUCTION

Silica nanoparticles (SiNPs) have been widely used in food, cosmetics, medicine and other fields; however, there have been growing concerns regarding their potential adverse effects on health. A large number of studies have confirmed that SiNPs with small particle diameters can pass through the blood brain barrier, causing irreversible damage to the nervous system. This study aims to further explore the molecular mechanism of neurotoxicity of SiNPs and provide a toxicological basis for the medical application of SiNPs.

METHODS

We conducted an in vitro study using neuroimmune cells (mouse microglial cells, BV2) of the central nervous system to study inflammation and ferroptosis after exposure to SiNPs. We detected cell viability, morphology and ultrastructure, antioxidant function, inflammation, and ferroptosis-related proteins to explore the role of pyroptosis and ferroptosis in the damage of BV2 cells induced by SiNPs. We further explored the relationship between the inflammatory response and ferroptosis induced by SiNPs by silencing the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) gene and inhibiting ferroptosis.

RESULTS

The results showed that SiNPs could invade the cytoplasm, change the ultrastructure, activate NLRP3 inflammasomes, release a large number of inflammatory factors, and trigger inflammatory reaction. We also found that SiNPs could disrupt cellular antioxidant function, increase intracellular ferrous ion level and induce ferroptosis. In addition, both inflammation and ferroptosis are alleviated in NLRP3 gene-silenced cells.

CONCLUSION

SiNPs could induce BV2 cytotoxicity through inflammatory response and ferroptosis, which may be mediated by the activation of the NLRP3 inflammasomes.

An overview of quantum dots-induced immunotoxicity and the underlying mechanisms

Quantum dots (QDs) have bright luminescence and excellent photostability. New synthesis techniques and strategies also enhance QDs properties for specific applications. With the continuous expansion of the applications, QDs-mediated immunotoxicity has become a major concern. The immune system has been confirmed to be an important target organ of QDs and is sensitive to QDs. Herein, review immunotoxic effects caused by QDs and the underlying mechanisms. Firstly, QDs exposure-induced modulation in immune cell maturation and differentiation is summarized, especially pre-exposed dendritic cells (DCs) and their regulatory roles in adaptive immunity. Cytokines are usually recognized as biomarkers of immunotoxicity, therefore, variation of cytokines mediated by QDs is also highlighted. Moreover, the activation of the complement system induced by QDs is discussed. Accumulated results have suggested that QDs disrupt the immune response by regulating intracellular oxidative stress (reactive oxygen species) levels, autophagy formation, and expressions of pro-inflammatory mediators. Furthermore, several signalling pathways play a key role in the disruption. Finally, some difficulties worthy of further consideration are proposed. Because there are still challenges in biomedical and clinical applications, this review hopes to provide information that could be useful in exploring the mechanisms associated with QD-induced immunotoxicity.

Cationic Carbon Nanoparticles Induce Inflammasome-Dependent Pyroptosis in Macrophages via Lysosomal Dysfunction

Carbon nanomaterials, including carbon dots (CDs), form a growing family of engineered nanoparticles (NPs) with widespread applications. As the rapid expansion of nanotechnologies raises safety concerns, interaction of NPs with the immune system is receiving a lot of attention. Recent studies have reported that engineered NPs may induce macrophage death by pyroptosis. Therefore, this study investigated whether cationic CDs induce pyroptosis in human macrophages and assessed the role of inflammasome and lysosome in this process. Cationic CDs were synthetized by microwave-assisted pyrolysis of citric acid and high molecular weight branched polyethyleneimine. The NPs evoked a dose-dependent viability loss in THP-1-derived macrophages. A cell leakage, an increase in IL-1β secretion and an activation of caspase-1 were also observed in response to the NPs. Inhibition of caspase-1 decreased CD-induced cell leakage and IL-1β secretion, while restoring cell viability. Besides, CDs triggered swelling and loss of integrity of lysosome, and inhibition of the lysosomal enzyme cathepsin B decreased CD-induced IL-1β secretion. Thus, our data provide evidence that cationic CDs induce inflammasome-dependent pyroptosis in macrophages via lysosomal dysfunction.

Olfactory bulb microglia activation mediated neuronal death in real-ambient particulate matter exposure mice with depression-like behaviors

Growing evidence has indicated that air pollution is associated with depression, and damage of olfactory bulb (OB) is regarded as an early marker for depression. However, the toxicity of fine particulate matter (PM_2.5) on OB and underlying mechanisms remains to be elucidated. In our study, a real-ambient PM_2.5 exposure system was applied to explore the effects of PM_2.5 on OB in C57BL/6 mice for 4 or 8 weeks. After 8 weeks exposure, the mice emerged potential depressive-like responses with reduction and disorder of cells in olfactory bulb tissues. Apoptosis and ultra-microstructure analysis indicated that the real-ambient PM_2.5 exposure caused the neuronal death of OB. The immunofluorescence observation and KEGG pathway analysis revealed the real-ambient PM_2.5 exposure induced microglia activation along with tumor necrosis factor α (TNFα)-mediated signaling enriched in OB of mice with depression-like behaviors. Moreover, results from ex vivo biosensor assay exhibited that PM_2.5 might trigger systemic inflammation with increased levels of various proinflammatory factors to activate microglia. Further in vitro co-culture model identified that the PM_2.5 evoked microglia cells activation with TNFα secretion and induced neuronal cells apoptosis via classical caspase3 signaling. Our findings provide new insights that PM_2.5 induced microglia activation characterized by the release of TNFα to cause neurotoxicity either by direct action or by circulatory inflammation, resulting in OB damage, which may play a critical role in early diagnosis and pathogenic mechanisms for PM_2.5 to cause depression.

A novel insight into mechanism of derangement of coagulation balance: interactions of quantum dots with coagulation-related proteins

Background

Quantum dots (QDs) have gained increased attention for their extensive biomedical and electronic products applications. Due to the high priority of QDs in contacting the circulatory system, understanding the hemocompatibility of QDs is one of the most important aspects for their biosafety evaluation. Thus far, the effect of QDs on coagulation balance haven’t been fully understood, and limited studies also have yet elucidated the potential mechanism from the perspective of interaction of QDs with coagulation-related proteins.

Results

QDs induced the derangement of coagulation balance by prolonging the activated partial thromboplastin time and prothrombin time as well as changing the expression levels of coagulation and fibrinolytic factors. The contact of QDs with PTM (prothrombin), PLG (plasminogen) and FIB (fibrinogen) which are primary coagulation-related proteins in the coagulation and fibrinolysis systems formed QDs-protein conjugates through hydrogen-bonding and hydrophobic interaction. The affinity of proteins with QDs followed the order of PTM > PLG > FIB, and was larger with CdTe/ZnS QDs than CdTe QDs. Binding with QDs not only induced static fluorescence quenching of PTM, PLG and FIB, but also altered their conformational structures. The binding of QDs to the active sites of PTM, PLG and FIB may promote the activation of proteins, thus interfering the hemostasis and fibrinolysis processes.

Conclusions

The interactions of QDs with PTM, PLG and FIB may be key contributors for interference of coagulation balance, that is helpful to achieve a reliable and comprehensive evaluation on the potential biological influence of QDs from the molecular level.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00458-x.

Protein corona mitigated the cytotoxicity of CdTe QDs to macrophages by targeting mitochondria

Despite the potential of cadmium telluride quantum dots (CdTe QDs) in bioimaging and drug delivery, their toxic effects have been documented. It is known that the immunotoxicity of CdTe QDs targeting macrophages is one of their adverse effects, and the protein corona (PC) will affect the biological effects of QDs. In order to prove whether the PC-CdTe QDs complexes could alleviate the toxicity of CdTe QDs without weakening their luminescence, we investigated the impact of protein corona formed in fetal bovine serum (FBS) on the cytotoxicity of CdTe QDs to mitochondria. RAW264.7 cells were used as the model to compare the effects of CdTe QDs and PC-CdTe QDs complexes on the structure, function, quantity, morphology, and mitochondrial quality control of mitochondria. As result, the protein corona form in FBS alleviated the inhibition of CdTe QDs on mitochondrial activity, the damage to mitochondrial membrane, the increase of ROS, and the reduction of ATP content. Also, CdTe QDs increased the number of mitochondria in macrophages, while the complexes did not. In line with this, the morphology of mitochondrial network in macrophages which were exposed to CdTe QDs and PC-CdTe QDs complexes was different. CdTe QDs transformed the network into fragments, punctuations, and short rods, while PC-CdTe QDs complexes made the mitochondrial network highly branched, which was related to the imbalance of mitochondrial fission and fusion. Mechanically, CdTe QDs facilitated mitochondrial fission and inhibited mitochondrial fusion, while protein corona reversed the phenomenon caused by QDs. Besides mitochondrial dynamics, mitochondrial biogenesis and mitophagy were also affected. CdTe QDs increased the expression of mitochondrial biogenesis signaling molecules including PGC-1α, NRF-1 and TFAM, while PC-CdTe QDs complexes played the opposite role. With regard to mitophagy, they both showed promoting effect. In conclusion, the formation of protein corona alleviated the toxic effects of CdTe QDs on the mitochondria in macrophages and affected mitochondrial quality control. Under the premise of ensuring the fluorescence properties of CdTe QDs, these findings provided useful insight into reducing the toxicity of CdTe QDs from two perspectives: protein corona and mitochondria, and shared valuable information for the safe use of QDs.

Immunomodulation by heavy metals as a contributing factor to inflammatory diseases and autoimmune reactions: Cadmium as an example

Cadmium (Cd) represents a unique hazard because of the long biological half-life in humans (20-30 years). This metal accumulates in organs causing a continuum of responses, with organ disease/failure as extreme outcome. Some of the cellular and molecular alterations in target tissues can be related to immune-modulating potential of Cd. This metal may cause adverse responses in which components of the immune system function as both mediators and effectors of Cd tissue toxicity, which, in combination with Cd-induced alterations in homeostatic reparative activities may contribute to tissue dysfunction. In this work, current knowledge concerning inflammatory/autoimmune disease manifestations found to be related with cadmium exposure are summarized. Along with epidemiological evidence, animal and in vitro data are presented, with focus on cellular and molecular immune mechanisms potentially relevant for the disease susceptibility, disease promotion, or facilitating development of pre-existing pathologies.

Systematic evaluation of CdSe/ZnS quantum dots toxicity on the reproduction and offspring health in male BALB/c mice

Increased applications of quantum dots (QDs) in the biomedical field have aroused attention for their potential toxicological effects. Although numerous studies have been carried out on the toxicity of QDs, their effects on reproductive and development are still unclear. In this study, we systematically evaluated the male reproductive toxicity and developmental toxicity of CdSe/ZnS QDs in BALB/c mice. The male mice were injected intravenously with CdSe/ZnS QDs at the dosage of 2.5 mg/kg BW or 25 mg/kg BW, respectively, and the survival status, biodistribution of QDs in testes, serum sex hormone levels, histopathology, sperm motility and acrosome integrity was measured on Day 1, 7, 14, 28 and 42 after injection. On Day 35 after treatment, male mice were housed with non-exposed female mice, and then offspring number, body weight, organ index and histopathology of major organs, blood routine and biochemical tests of offspring were measured to evaluate the fertility and offspring health. The results showed that CdSe/ZnS QDs could rapidly distribute in the testis, and the fluorescence of QDs could still be detected on Day 42 post-injection. QDs had no adverse effect on the structure of testis and epididymis, but high-dose QDs could induce apoptosis of Leydig cells in testis at an early stage. No significant differences in survival of state, body weight organ index of testis and epididymis, sex hormones levels, sperm quality, sperm acrosome integrity and fertility of male mice were observed in QDs exposed groups. However, the development of offspring was obviously influenced, which was mainly manifested in the slow growth of offspring, changes in organ index of main organs, and the abnormality of liver and kidney function parameters. Our findings revealed that CdSe/ZnS QDs were able to cross the blood-testis barrier (BTB), produce no discernible toxic effects on the male reproductive system, but could affect the healthy growth of future generations to some extent. In view of the broad application prospect of QDs in biomedical fields, our findings might provide insight into the biological safety evaluation of the reproductive health of QDs.

Immunotoxicology of cadmium: Cells of the immune system as targets and effectors of cadmium toxicity

Cadmium (Cd) has been listed as one of the most toxic substances affecting numerous tissues/organs, including the immune system. Due to variations in studies examining Cd effects on the immune system (exposure regime, experimental systems, immune endpoint measured), data on Cd immunotoxicity in humans and experimental animals are inconsistent. However, it is clear that Cd can affect cells of the immune system and can modulate some immune responses. Due to the complex nature of the immune system and its activities which are determined by multiple interactions, the underlying mechanisms involved in the immunotoxicity of this metal are still vague. Here, the current knowledge regarding the interaction of Cd with cells of the immune system, which may affect immune responses as well as potential mechanisms of consequent biological effects of such activities, is reviewed. Tissue injury caused by Cd-induced effects on innate cell activities depicts components of the immune system as mediators/effectors of Cd tissue toxicity. Cd-induced immune alterations, which may compromise host defense against pathogenic microorganisms and homeostatic reparative activities, stress this metal as an important health hazard.

CdSe/ZnS Core-Shell-Type Quantum Dot Nanoparticles Disrupt the Cellular Homeostasis in Cellular Blood-Brain Barrier Models

Two immortalized brain microvascular endothelial cell lines (hCMEC/D3 and RBE4, of human and rat origin, respectively) were applied as an in vitro model of cellular elements of the blood–brain barrier in a nanotoxicological study. We evaluated the impact of CdSe/ZnS core-shell-type quantum dot nanoparticles on cellular homeostasis, using gold nanoparticles as a largely bioorthogonal control. While the investigated nanoparticles had surprisingly negligible acute cytotoxicity in the evaluated models, a multi-faceted study of barrier-related phenotypes and cell condition revealed a complex pattern of homeostasis disruption. Interestingly, some features of the paracellular barrier phenotype (transendothelial electrical resistance, tight junction protein gene expression) were improved by exposure to nanoparticles in a potential hormetic mechanism. However, mitochondrial potential and antioxidant defences largely collapsed under these conditions, paralleled by a strong pro-apoptotic shift in a significant proportion of cells (evidenced by apoptotic protein gene expression, chromosomal DNA fragmentation, and membrane phosphatidylserine exposure). Taken together, our results suggest a reactive oxygen species-mediated cellular mechanism of blood–brain barrier damage by quantum dots, which may be toxicologically significant in the face of increasing human exposure to this type of nanoparticles, both intended (in medical applications) and more often unintended (from consumer goods-derived environmental pollution).

Microarray analysis of gene expression differences in microglia after exposure to graphene quantum dots

Graphene quantum dots (GQDs) have been broadly applied in biomedicine in recent years. So far, researches have reported that GQDs might contribute to the injury of the central nervous system (CNS), yet the latent toxicological mechanism is not clear. This study aims to investigate the underlying biological mechanism responsible for the neurotoxicity of nitrogen-doped GQDs (N-GQDs) and amino-functionalized GQDs (A-GQDs) by use of genome-wide transcription microarray. The findings showed that 174 and 1341 genes were altered significantly in the BV2 cells treated by 25 μg/mL N-GQDs and 100 μg/mL N-GQDs compared with the control, respectively. As for the BV2 cells exposed to 100 μg/mL A-GQDs, 1396 diversely expressed genes were detected. By comparing the 100 μg/mL N-GQDs exposed group with 100 μg/mL A-GQDs exposed group, the expression of 256 genes was extensively altered, including 58 upregulated genes and 198 downregulated genes. From Gene Ontology (GO) analysis, the altered genes were mainly enriched in functions of ion channel activation and cellular processes. Based on the KEGG pathway and signal-net analysis, the toxicity of GQDs in BV2 cells was closely related to calcium signaling pathway, cell cycle and endocytosis. And the pathways that the shared mRNAs involved all served as the crucial roles in the neurotoxicity of GQDs despite the chemical functionalization (N-GQDs or A-GQDs). In addition, the consequences from qRT-PCR, Western blot, intracellular calcium level measurements and comet assay further confirmed that calcium dyshomeostasis, DNA damage and cell cycle arrest were the key factors responsible for the GQDs-induced neurotoxicity through affecting several classical signaling pathways. In conclusion, our research will supply essential data for further studies on mechanisms of GQDs-induced neurotoxicity by use of genome-wide screening.