Titanium Dioxide Nanoparticles Exacerbate Allergic Airway Inflammation via TXNIP Upregulation in a Mouse Model of Asthma

The absence of thioredoxin-interacting protein in alveolar cells exacerbates asthma during obesity

Obesity is associated with an increased incidence of asthma. However, the mechanisms underlying this association are not fully understood. In this study, we investigated the role of thioredoxin-interacting protein (TXNIP) in obesity-induced asthma. Asthma was induced by intranasal injection of a protease from Aspergillus oryzae in normal diet (ND)- or high fat diet (HFD)-fed mice to investigate the symptoms. We measured TXNIP expression in the lungs of patients with asthma and in ND or HFD asthmatic mice. To explore the role of TXNIP in asthma pathogenesis, we induced asthma in the same manner in alveolar type 2 cell-specific TXNIP deficient (TXNIPCre) mice. In addition, the expression levels of pro-inflammatory cytokines were compared based on TXNIP gene expression in A549 cells stimulated with recombinant human tumor necrosis factor alpha. Compared to ND-fed mice, HFD-fed mice had elevated levels of free fatty acids and adipokines, resulting in high reactive oxygen species levels and more severe asthma symptoms. TXNIP expression was increased in both, asthmatic patients and HFD asthmatic mice. However, in experiments using TXNIPCre mice, despite being TXNIP deficient, TXNIPCre mice exhibited exacerbated asthma symptoms. Consistent with this, in vitro studies showed highest expression levels of pro-inflammatory cytokines in TXNIP-silenced cells. Overall, our findings suggest that increased TXNIP levels in obesity-induced asthma is compensatory to protect against inflammatory responses.

Ezetimibe ameliorates cisplatin-induced nephrotoxicity: A novel therapeutic approach via modulating AMPK/Nrf2/TXNIP signaling

Cisplatin (Cis) is among the most powerful antineoplastic medications, nevertheless, its serious side effects; particularly nephrotoxicity designates a major concern. Previous studies reported that ezetimibe (Eze), a well-known antihyperlipidemic drug, exerts additional trivial pharmacological effects. In this work, we displayed Eze as an intriguing protective candidate in a cisplatin-induced nephrotoxicity rat model through AMPK activation. Eze (10 mg/kg, p.o.) was administered for two weeks and Cis (10 mg/kg, i.p.) was administered on the 10th day to induce nephrotoxicity in male Wistar rats. Treatment with Eze greatly augmented the phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK) and the antioxidant regulator; nuclear factor erythroid 2-related factor 2 (Nrf2), thus, mitigating oxidative injury through induction of the antioxidant enzymes, such as heme oxygenase-1 (HO-1) and glutathione reductase (GR). As well, Eze relieved inflammation by reducing protein expression of thioredoxin-interacting protein (TXNIP) and nucleotide-binding domain-like receptor protein 3 (NLRP3), which led to a decrease in the release of caspase-1, in addition to, the inflammatory markers IL-18 and IL-1 β. Besides, Eze ameliorated apoptosis in the renal cells through inhibiting the phosphorylated Apoptosis signal-regulating kinase-1(p-ASK1), caspase-3 and reducing Bax/Bcl2ratio. Correspondingly, histopathological examination corroborated the previous biochemical findings. Collectively, Eze exerts significant renal protection against Cis-induced nephrotoxicity via antioxidant, anti-inflammatory and anti-apoptotic pathways that are probably mediated, at least partly, via activating AMPK/Nrf2/HO-1 pathway and conquering both TXNIP/NLRP3 inflammasome and TXNIP/ASK1 signaling pathways. To confirm the protective effect of Eze via AMPK-activation, an AMPK-inhibitor, dorsomorphin (Dors), when co-administered with Eze abolished its protective effect.

Toxicity and Mechanisms of Engineered Nanoparticles in Animals with Established Allergic Asthma

Asthma is a chronic respiratory disease that is highly sensitive to environmental pollutants, including engineered nanoparticles (NPs). Exposure to NPs has become a growing concern for human health, especially for susceptible populations. Toxicological studies have demonstrated strong associations between ubiquitous NPs and allergic asthma. In this review, we analyze articles that focus on adverse health effects induced by NPs in animal models of allergic asthma to highlight their critical role in asthma. We also integrate potential mechanisms that could stimulate and aggravate asthma by NPs. The toxic effects of NPs are influenced by their physicochemical properties, exposure dose, duration, route, as well as the exposure order between NPs and allergens. The toxic mechanisms involve oxidative stress, various inflammasomes, antigen presenting cells, immune cells, and signaling pathways. We suggest that future research should concentrate on establishing standardized models, exploring mechanistic insights at the molecular level, assessing the combined effects of binary exposures, and determining safe exposure levels of NPs. This work provides concrete evidence of the hazards posed by NPs in animals with compromised respiratory health and supports the modifying role of NPs exposure in allergic asthma.

Toll-like receptor 4 is a key regulator of asthma exacerbation caused by aluminum oxide nanoparticles via regulation of NF-κB phosphorylation

Aluminum oxide nanoparticles (Al₂O₃ NPs) have recently been reported to cause an inflammatory response in the lungs, and studies are being conducted on their adverse effects, especially in patients with underlying lung diseases such as asthma. However, the underlying mechanism of asthma aggravation caused by Al₂O₃ NPs remains unclear. This study investigated whether Al₂O₃ NPs exacerbate ovalbumin (OVA)-induced asthma and focused on the correlation between toll-like receptor 4 (TLR4) signaling and Al₂O₃ NP-induced asthma exacerbation. Al₂O₃ NP exposure in asthmatic mice resulted in increased inflammatory cell counts in the lungs, airway hyperresponsiveness, and increased levels of inflammatory cytokines compared with only OVA-induced mice, and excessive secretion of mucus was observed in the airways. Moreover, Al₂O₃ NP exposure in OVA-induced mice increased the expression levels of TLR4, phospho-nuclear transcription factor-kappa B (p-NFκB), myeloid differentiation factor 88 (MyD88), and phospho-NF kappa B inhibitor alpha (p-IκBα). Furthermore, in the lungs of TLR4 knockout mice exposed to Al₂O₃ NPs and in a human airway epithelial cell line with down regulated TLR4, the expression levels of MyD88, p-NFκB, and p-IκBα were decreased, and asthma-related allergic responses were reduced. Therefore, we demonstrated that TLR4 is important for aggravation of asthma induced by Al₂O₃ NPs, and this study provides useful information regarding as yet undiscovered novel target signaling.

Applications of Titanium Dioxide Nanostructure in Stomatology

Breakthroughs in the field of nanotechnology, especially in nanochemistry and nanofabrication technologies, have been attracting much attention, and various nanomaterials have recently been developed for biomedical applications. Among these nanomaterials, nanoscale titanium dioxide (nano-TiO₂) has been widely valued in stomatology due to the fact of its excellent biocompatibility, antibacterial activity, and photocatalytic activity as well as its potential use for applications such as dental implant surface modification, tissue engineering and regenerative medicine, drug delivery carrier, dental material additives, and oral tumor diagnosis and treatment. However, the biosafety of nano-TiO₂ is controversial and has become a key constraint in the development of nano-TiO₂ applications in stomatology. Therefore, in this review, we summarize recent research regarding the applications of nano-TiO₂ in stomatology, with an emphasis on its performance characteristics in different fields, and evaluations of the biological security of nano-TiO₂ applications. In addition, we discuss the challenges, prospects, and future research directions regarding applications of nano-TiO₂ in stomatology that are significant and worthy of further exploration.

Inner Shell of the Chestnut (Castanea crenatta) Suppresses Inflammatory Responses in Ovalbumin-Induced Allergic Asthma Mouse Model

The inner shell of the chestnut (Castanea crenata) contains various polyphenols, which exert beneficial biological effects. Hence, we assessed the anti-inflammatory efficacy of a chestnut inner shell extract (CIE) in ovalbumin (OVA)-induced allergic asthma. We intraperitoneally injected 20 μg of OVA with 2 mg of aluminum hydroxide on days 0 and 14. On test days 21, 22, and 23, the mice were treated with aerosolized 1% (w/v) OVA in saline. CIE was administered orally at 100 and 300 mg/kg on days 18-23. CIE significantly reduced inflammatory cytokines and cells and immunoglobulin-E increased by OVA. Anti-inflammatory efficacy was revealed by reduction of inflammatory cell migration and mucus secretion in lung tissue. Further, CIE suppressed the OVA-induced nuclear factor kappa B (NF-κB) phosphorylation. Accordingly, the expression of cyclooxygenase (COX-2), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase-9 (MMP-9) were decreased sequentially in lung tissues. CIE alleviated OVA-induced airway inflammation by restraining phosphorylation of NF-κB and the sequentially reduced expression of iNOS, COX-2, leading to reduced MMP-9 expression. These results indicate that CIE has potential as a candidate for alleviating asthma.

Thioredoxin-1: A Promising Target for the Treatment of Allergic Diseases

Thioredoxin-1 (Trx1) is an important regulator of cellular redox homeostasis that comprises a redox-active dithiol. Trx1 is induced in response to various stress conditions, such as oxidative damage, infection or inflammation, metabolic dysfunction, irradiation, and chemical exposure. It has shown excellent anti-inflammatory and immunomodulatory effects in the treatment of various human inflammatory disorders in animal models. This review focused on the protective roles and mechanisms of Trx1 in allergic diseases, such as allergic asthma, contact dermatitis, food allergies, allergic rhinitis, and drug allergies. Trx1 plays an important role in allergic diseases through processes, such as antioxidation, inhibiting macrophage migration inhibitory factor (MIF), regulating Th1/Th2 immune balance, modulating allergic inflammatory cells, and suppressing complement activation. The regulatory mechanism of Trx1 differs from that of glucocorticoids that regulates the inflammatory reactions associated with immune response suppression. Furthermore, Trx1 exerts a beneficial effect on glucocorticoid resistance of allergic inflammation by inhibiting the production and internalization of MIF. Our results suggest that Trx1 has the potential for future success in translational research.

Upcycling discarded cellulosic surgical masks into catalytically active freestanding materials

ABSTRACT

The COVID-19 pandemic outbreak has resulted in the massive fabrication of disposable surgical masks. As the accumulation of discarded face masks represents a booming threat to the environment, here we propose a solution to reuse and upcycle surgical masks according to one of the cornerstones of the circular economy. Specifically, the non-woven cellulosic layer of the masks is used as an environmentally sustainable and highly porous solid support for the controlled deposition of catalytically active metal-oxide nanoparticles. The native cellulosic fibers from the surgical masks are decorated by titanium dioxide (TiO2), iron oxide (FexOy), and cobalt oxide (CoOx) nanoparticles following a simple and scalable approach. The abundant surface -OH groups of cellulose enable the controlled deposition of metal-oxide nanoparticles that are photocatalytically active or shown enzyme-mimetic activities. Importantly, the hydrophilic highly porous character of the cellulosic non-woven offers higher accessibility of the pollutant to the catalytically active surfaces and high retention in its interior. As a result, good catalytic activities with long-term stability and reusability are achieved. Additionally, developed free-standing hybrids avoid undesired media contamination effects originating from the release of nanoscale particles. The upcycling of discarded cellulosic materials, such as the ones of masks, into high-added-value catalytic materials, results an efficient approach to lessen the waste´s hazards of plastics while enhancing their functionality. Interestingly, this procedure can be extended to the upcycling of other systems (cellulosic or not), opening the path to greener manufacturing approaches of catalytic materials.

GRAPHICAL ABSTRACT

A novel approach to upcycle discarded cellulosic surgical masks is proposed, providing a solution to reduce the undesired accumulation of discarded face masks originating from the COVID-19 pandemic. The non-woven cellulosic layer formed by fibers is used as solid support for the controlled deposition of catalytically active titanium dioxide (TiO2), iron oxide (FexOy), and cobalt oxide (CoOx) nanoparticles. Cellulosic porous materials are proven useful for the photocatalytic decomposition of organic dyes, while their peroxidase-like activity opens the door to advanced applications such as electrochemical sensors. The upcycling of cellulose nonwoven fabrics into value-added catalytic materials lessens the waste´s hazards of discarded materials while enhancing their functionality.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10570-022-04441-9.