Environmentally Relevant Concentrations of Microplastic Exposure Cause Cholestasis and Bile Acid Metabolism Dysregulation through a Gut-Liver Loop in Mice.

The massive production of plastics causes the ubiquitous existence of microplastics (MPs) in the biota, therefore, posing exposure risks and potential health concerns to human beings. However, the exact mechanisms of MPs-induced toxicities and abnormalities are largely unknown. In this study, we developed a mouse model of gavage polystyrene microplastics (PS MPs) for 30 days. We found that PS MPs can damage the intestinal barrier, accumulate in the liver tissue, and cause injury. The liver and intestine are both highly associated with bile acid (BA) metabolism. Indeed, we found that PS MPs dysregulate BA synthesis and efflux-related gene expression in the liver, causing cholestasis. Tandemly, PS MPs alter the ratio of primary to secondary BA in the feces by affecting the composition of the intestinal flora. At last, PS MPs alter mice's fecal BA profile, which affects normal BA metabolism. Taken together, the present study provides robust data on the mechanism of toxicity of MPs causing the disturbance of BA metabolism via a 4-step gut-liver loop.

Polystyrene Nanoplastics Induce Neutrophil Extracellular Traps in Mice Neutrophils.

With growing applications of plastic products, there is a growing threat to human health. Therefore, it is important to understand their toxicological behaviors. The release of neutrophil extracellular traps (NETs) was clarified as a new immune defense mechanism against intruders. Here, we discovered that polystyrene nanoplastics (PS NPs) induce NET formation, with involvement of reactive oxygen species, peptidyl arginine deiminase 4 (PAD4), and neutrophil elastase. Moreover, overexpression of PAD4 induced by PS NPs further mediates histone citrullination and chromatin depolymerization. These results provide important information and promising strategies for safety and immunotoxicity assessment of NPs.

Impact of Protein Corona on Noncovalent Molecule-Gold Nanoparticle-Based Sensing.

Gold nanoparticle (AuNP)-based sensors have been extensively applied for sensing or imaging. It is known that a protein shell named protein corona (PC) formed around the nanomaterials could not only block the desired function of nanomaterials but also affect their behavior, which is a hot and important issue needing consideration. Therefore, we hypothesize that the formation of PC around AuNPs could inevitably affect the AuNP-based target assay. In this work, the effects of PC on the detection results in sensors based on AuNPs were studied. Three types of noncovalent molecule-AuNP sensors including AuNP-dichlorofluorescein, AuNP-aptamer, and AuNP-antibody-DNA were constructed, and several typical proteins (bovine serum albumin, fibrinogen, hemoglobin, and ß-lactoglobulin), milk, and fetal bovine serum were selected as models for the formation of PCs. This study shows that the PC could cause the loss of detection signals (up to 80%) and result in positive deviation of the measuring value compared with the true value. Moreover, the loss of detection signals could also increase the limits of detection (almost 10 times), decreasing the sensitivity of the three types of sensors, as proposed in this work compared to that without PC. Moreover, the polyethylene glycol backfilling strategy could not resolve the negative effects of PC on noncovalent molecule-AuNP sensors. The impacts of PC on detection results from noncovalent molecule-AuNP sensors would cause misdiagnosis or wasted production, which needs careful reconsideration of the AuNP-based detection in application fields like clinic diagnosis, food safety control, and so forth.

Compromised Autophagic Effect of Polystyrene Nanoplastics Mediated by Protein Corona Was Recovered after Lysosomal Degradation of Corona.

The adverse biological and ecological consequences of plastic debris have become a serious problem worldwide. Evidences have uncovered the accumulation of nanoplastics (NPs) in organisms. In a complex biological environment, proteins are prone to adsorbed onto the NPs' surface and form a protein corona layer, which mediates the interaction of NPs with cells. Here, we discovered the interaction of polystyrene (PS) NPs with protein fetal bovine serum (FBS) and altered cytotoxic effects. Mechanistically, prefabricated FBS protein corona mediated the relief of autophagic flux blockage, autophagosomes accumulation, and lysosomal damage in RAW264.7 cells caused by PS NPs. Using an individual fluorescent protein bovine serum albumin (BSA) as a corona surrogate, we demonstrated that coronal BSA remains, at least partially, on the surface of PS NPs during the initial stage of internalization and protects cell membrane from PS NPs-induced damage. However, along with the degradation of corona in lysosomes, reappearance of cytotoxicity was observed. Herein, we provided a proof of principle of the manipulation of corona on NPs' toxicity and we expect the result will promote the further safety assessment of NPs.

Self-assembled, aptamer-tethered DNA nanotrains for targeted transport of molecular drugs in cancer theranostics.

Nanotechnology has allowed the construction of various nanostructures for applications, including biomedicine. However, a simple target-specific, economical, and biocompatible drug delivery platform with high maximum tolerated doses is still in demand. Here, we report aptamer-tethered DNA nanotrains (aptNTrs) as carriers for targeted drug transport in cancer therapy. Long aptNTrs were self-assembled from only two short DNA upon initiation by modified aptamers, which worked like locomotives guiding nanotrains toward target cancer cells. Meanwhile, tandem "boxcars" served as carriers with high payload capacity of drugs that were transported to target cells and induced selective cytotoxicity. aptNTrs enhanced maximum tolerated dose in nontarget cells. Potent antitumor efficacy and reduced side effects of drugs delivered by biocompatible aptNTrs were demonstrated in a mouse xenograft tumor model. Moreover, fluorophores on nanotrains and drug fluorescence dequenching upon release allowed intracellular signaling of nanotrains and drugs. These results make aptNTrs a promising targeted drug transport platform for cancer theranostics.

Long-term polystyrene nanoplastic exposure disrupt hepatic lipid metabolism and cause atherosclerosis in ApoE-/- mice.

Nanoplastics (NPs) exposure is usually linked with abnormal inflammation and oxidative stress, which are high-risk triggers of atherosclerosis; however, whether this exposure causes the development of atherosclerosis is vague. Here, we found that PS NPs co-exposure with ox-LDL induces significant accumulation of lipid, as well as oxidative stress and inflammation in RAW264.7 macrophages. Using an ultrasound biomicroscope (UBM), we observed the emergence of atherosclerotic plaques at the aortic arch of apolipoprotein knockout (ApoE-/-) mice after being exposed to PS NPs for three months. Oil-red O and hematoxylin-eosin (H&E) staining at the mice's aortic root also observed the deposition of lipids with plaque formation. Moreover, the development of atherosclerotic disease is associated with disturbances in lipid metabolism and oxidative stress damage in the mice liver. In conclusion, this study provides additional evidence to further understand the possible cardiovascular damage caused by NPs exposure.

Oral exposure of polystyrene microplastics and doxycycline affects mice neurological function via gut microbiota disruption: The orchestrating role of fecal microbiota transplantation.

The debris of plastics with a size < 5 mm, called microplastics, possess long-lived legacies of plastic pollution and a growing threat to human beings. The adverse effects and corresponding molecular mechanisms of microplastics are still largely unknown and must be prioritized. Antibiotics commonly co-existed with microplastics; the current study investigated the syngenetic toxic effect of doxycycline (Dox) and polystyrene microplastics (PS). Specifically, we found that Dox combined with PS exposure perturbed gut microbiota homeostasis in mice, which mediated brain lesions and inflammation with a concomitant decline in learning and memory behaviors through the gut-brain axis. Of note, PS exposure resulted in intestinal damage and structural change, but Dox did not accelerate the disruption of intestinal barrier integrity in PS-treated mice. Interestingly, fecal microbiota transplantation (FMT) can reverse neurological impairment caused by combined PS and Dox exposure via compensating gut microbes; therefore, the learning and memory abilities of mice were also recovered. This work not only provides insights into the syngenetic effect of microplastics and antibiotics and highlights their distal neurotoxicity through the gut-brain axis but also offers a promising strategy against their combined toxicity.

Polystyrene nanoparticles trigger aberrant condensation of TDP-43 and amyotrophic lateral sclerosis-like symptoms.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the dysfunction and progressive death of cerebral and spinal motor neurons. Preliminary epidemiological research has hinted at a relationship between environmental risks and the escalation of ALS, but the underlying reasons remain mostly mysterious. Here we show that nanosize polystyrene plastics (PS) induce ALS-like symptoms and illustrate the related molecular mechanism. When exposed to PS, cells endure internal oxidative stress, which leads to the aggregation of TAR DNA-binding protein 43 kDa (TDP-43), triggering ALS-like characteristics. In addition, the oxidized heat shock protein 70 fails to escort TDP-43 back to the nucleus. The cytoplasmic accumulation of TDP-43 facilitates the formation of a complex between PS and TDP-43, enhancing the condensation and solidification of TDP-43. These findings are corroborated through in silico and in vivo assays. Altogether, our work illustrates a unique toxicological mechanism induced by nanoparticles and provides insights into the connection between environmental pollution and neurodegenerative disorders.

Iron ion and sulfasalazine-loaded polydopamine nanoparticles for Fenton reaction and glutathione peroxidase 4 inactivation for enhanced cancer ferrotherapy.

Ferroptosis shows promising potential in tumor treatment; however, factors that compromise the efficiency of the Fenton catalyst have limited its therapeutic effectiveness. We developed a polydopamine-based nanoplatform constructed with ferric ion and sulfasalazine-loaded nanoparticles (Fe(III)PP@SAS NPs) for dual-functional ferrotherapy strategy of "sword and shield" through enhanced Fenton reaction and inactivation of glutathione peroxidase 4 (GPX4), respectively. Both the Fenton reaction-based hydroxyl radical (·OH) production and sulfasalazine-driven GPX4 inhibition induced ferroptotic cell death, thus achieving synergistic cancer therapy. Near-infrared light irradiation and acidic tumor microenvironment enhanced the release of ferric ions and sulfasalazine from the Fe(III)PP@SAS NPs. In addition, the released iron ions underwent valence state change due to Fenton reaction and thus provided a supplementary T1-weighted signal for in situ visualization of the tumor based on magnetic resonance imaging. The Fe(III)PP@SAS NPs exhibited high pro-ferroptosis performance by utilizing ·OH radicals as a "sword" to attack cancer cells and the GPX4 inhibitor to break down the "shield" of cancer cells, thus showing potential for cancer treatment. STATEMENT OF SIGNIFICANCE: Several strategies of cancer therapy based on ferroptosis have emerged in recent years, which have provided new insights into designing materials for therapeutic applications. The antitumor efficacy of ferroptosis is, however, still unsatisfactory, mainly because of insufficient intracellular pro-ferroptotic stimuli. In the current study, we report a multifunctional theranostic nanoplatform, namely Fe(III)PP@SAS, with three-fold synergistic effect; this nanoplatform has excellent theranostic potential with multifunctional ferrotherapy.

Tumor cell targeting using folate-conjugated fluorescent quantum dots and receptor-mediated endocytosis.

BACKGROUND: Luminescent nanobioprobes with cell-targeting specificity are likely to find important applications in bioanalysis, biomedicine, and clinical diagnosis. Quantum dots (QDs) are unique and promising materials for such a purpose because of their fluorescence and large surface area for attaching cell-targeting molecules. METHODS: We produced water-dispersible QDs by coating hydrophobic QDs with small amphiphilic polyethylene glycol (PEG) molecules via hydrophobic interactions. We covalently coupled folate (FA) onto the water-dispersible PEG-coated QDs (PEG-QDs) to produce FA-coupled PEG-QDs (FA-PEG-QDs). RESULTS: These FA-PEG-QD nanoparticles functioned as fluorescent nanobioprobes that specifically recognized folate receptors (FRs) overexpressed in human nasopharyngeal cells (KB cells) but not in an FR-deficient lung carcinoma cell line (A549 cells). Using confocal fluorescence microscopy, we demonstrated uptake of FA-PEG-QDs by KB cells but no uptake of folate-free PEG-QDs. The specificity of this receptor-mediated internalization was confirmed by comparing the uptake by KB vs A549 cells. CONCLUSIONS: Our results suggest that such cell-targeting fluorescent nanobioprobes are potentially very powerful tools for recognizing target cells and delivering and tracking drugs and other therapeutic materials.

C6-ceramide nanoliposome suppresses tumor metastasis by eliciting PI3K and PKCζ tumor-suppressive activities and regulating integrin affinity modulation.

Nanoliposomal formulation of C6-ceramide, a proapoptotic sphingolipid metabolite, presents an effective way to treat malignant tumor. Here, we provide evidence that acute treatment (30 min) of melanoma and breast cancer cells with nanoliposomal C6-ceramide (NaL-C6) may suppress cell migration without inducing cell death. By employing a novel flow migration assay, we demonstrated that NaL-C6 decreased tumor extravasation under shear conditions. Compared with ghost nanoliposome, NaL-C6 triggered phosphorylation of PI3K and PKCζ and dephosphorylation of PKCα. Concomitantly, activated PKCζ translocated into cell membrane. siRNA knockdown or pharmacological inhibition of PKCζ or PI3K rescued NaL-C6-mediated suppression of tumor migration. By inducing dephosphorylation of paxillin, PKCζ was responsible for NaL-C6-mediated stress fiber depolymerization and focal adhesion disassembly in the metastatic tumor cells. PKCζ and PI3K regulated cell shear-resistant adhesion in a way that required integrin αvß3 affinity modulation. In conclusion, we identified a novel role of acute nanoliposomal ceramide treatment in reducing integrin affinity and inhibiting melanoma metastasis by conferring PI3K and PKCζ tumor-suppressive activities.

A spherical nucleic acid platform based on self-assembled DNA biopolymer for high-performance cancer therapy.

Based on their enhanced cellular uptake, stability, biocompatibility, and versatile surface functionalization, spherical nucleic acids (SNAs) have become a potentially useful platform in biological applications. It still remains important to expand the SNAs' "toolbox", especially given the current interest in multimodal or theranostic nanomaterials, that is, composites capable of multiple simultaneous applications such as imaging, sensing, and drug delivery. In this paper, we have engineered a nanoparticle-conjugated initiator that triggers a cascade of hybridization reactions resulting in the formation of a long DNA polymer as the nanoparticle shell. By employing different DNA fragments, self-assembled multifunctional SNAs can be constructed. Therefore, using one capped ligand, these SNAs can combine imaging fluorescent tags, target recognition element, and targeted delivery molecules together. Since these SNAs possess high drug loading capacity and high specificity by the incorporation of an aptamer, our approach might find potential applications in new drug development, existing drug improvement, and drug delivery for cancer therapy.