Presence of Titanium and Toxic Effects Observed in Rat Lungs, Kidneys, and Central Nervous System in vivo and in Cultured Astrocytes in vitro on Exposure by Titanium Dioxide Nanorods

The toxicological effects of nano titanium dioxide on target organs and mechanisms of toxicity

Nano-titanium dioxide (TiO2 NPs) is widely used for its extremely high stability, corrosion resistance, and photocatalytic properties and has penetrated into various fields of production and life. Assessing its toxicity to different organs should be a key part of preclinical toxicity assessment of TiO2 NPs, which is relatively incomprehensive yet. Therefore, this review focuses on the toxic effects of TiO2 NPs on various organs in mammals and biological mechanisms from different organs. The commonality of toxic effects on various target organs reflected in tissue structure damage and dysfunction, such as liver damage and dysfunction; pulmonary fibrosis; and renal impairment (including hematuria and nephritis); damage of brain tissue and neurons; alteration of intestinal villi; and weight loss. And effects on the reproductive system are affected by different sexes, including ovarian dysfunction, testicular development damage, and sperm viability reduction. We believe that the toxic mechanisms of TiO2 NPs in target organs have commonalities, such as oxidative stress, inflammatory responses, and organelle damage. However, different target organ toxicities also have their specificities. TiO2 NPs disturb the intestinal flora and cause undesirable changes in feces products. And in spleen are infiltration of neutrophils and lymphadenopathy and eventually immune deficiency. Although the toxic pathways are different, but there may be a close link between the different toxic pathways. In this article, the main manifestations of the toxic effects of titanium dioxide nanoparticles on major mammalian organs are reviewed, in order to provide basic data for their better application from a medical perspective.

Neurotoxicity of Titanium Dioxide Nanoparticles: A Comprehensive Review

The increasing use of titanium dioxide nanoparticles (TiO2 NPs) across various fields has led to a growing concern regarding their environmental contamination and inevitable human exposure. Consequently, significant research efforts have been directed toward understanding the effects of TiO2 NPs on both humans and the environment. Notably, TiO2 NPs exposure has been associated with multiple impairments of the nervous system. This review aims to provide an overview of the documented neurotoxic effects of TiO2 NPs in different species and in vitro models. Following exposure, TiO2 NPs can reach the brain, although the specific mechanism and quantity of particles that cross the blood-brain barrier (BBB) remain unclear. Exposure to TiO2 NPs has been shown to induce oxidative stress, promote neuroinflammation, disrupt brain biochemistry, and ultimately impair neuronal function and structure. Subsequent neuronal damage may contribute to various behavioral disorders and play a significant role in the onset and progression of neurodevelopmental or neurodegenerative diseases. Moreover, the neurotoxic potential of TiO2 NPs can be influenced by various factors, including exposure characteristics and the physicochemical properties of the TiO2 NPs. However, a systematic comparison of the neurotoxic effects of TiO2 NPs with different characteristics under various exposure conditions is still lacking. Additionally, our understanding of the underlying neurotoxic mechanisms exerted by TiO2 NPs remains incomplete and fragmented. Given these knowledge gaps, it is imperative to further investigate the neurotoxic hazards and risks associated with exposure to TiO2 NPs.

Association of Different Total Bilirubin Levels with Prognosis of Peritoneal Dialysis-Associated Peritonitis

Background and Objectives: Peritoneal dialysis-associated peritonitis (PDAP) poses significant challenges in peritoneal dialysis (PD) patient management and outcomes. Total bilirubin has gained attention due to its antioxidant and immunomodulatory properties. However, its relationship with PDAP prognosis remains underexplored. Materials and Methods: We conducted a retrospective single-center study involving 243 PDAP patients stratified into tertile-based groups according to total bilirubin levels. The association between total bilirubin levels and treatment failure risk was investigated through statistical analyses and restricted cubic spline curve analysis. Results: Our analysis revealed a non-linear correlation between total bilirubin levels and PDAP treatment failure risk. At total bilirubin levels below 8.24 µmol/L, a protective effect was observed, while levels exceeding this threshold heightened the risk of treatment failure. Conclusions: This study unveils a dual role of total bilirubin in PDAP prognosis. Below a certain threshold, it confers protection, while higher levels exacerbate the risk of treatment failure. These findings emphasize the need for further investigation in larger, multicenter prospective studies to validate and elucidate the mechanisms behind bilirubin's impact on PDAP, potentially guiding the development of targeted therapeutic strategies.

Glabridin mitigates TiO2NP induced cognitive deficit in adult zebrafish

Glabridin is extracted from the roots of Glycyrrhiza glabra, which has anti-oxidative and anti-inflammatory properties. We investigated the neuroprotective potential of Glabridin against the learning and memory deficit by triggering NRF2/HO-1 signaling in Titanium dioxide nanoparticles (TiO2NP) treated zebrafish. Our study suggests that Glabridin at doses of 12.5, 25, and 50 mg/kg/day for 7 days improved memory and lowered anxiety in the novel object recognition test, T-maze, and novel diving tank respectively. Biochemical analysis showed that Glabridin treatment in TiO2NP-exposed zebrafish enhanced GSH, CAT, SOD, and GPx activity and reduced MDA levels; inhibited proinflammatory mediators, namely, TNF-α, IL-1β, and IL-6. In histopathological evaluation, Glabridin significantly reduced pycnotic neurons in TiO2NP-treated zebrafish brains. Furthermore, Glabridin upregulated NRF2 and HO-1 levels, which leads to a decline in oxidative stress and neuroinflammation and were reversed by ML385 treatment. ML385 as a probe molecule that specifically inhibit NRF2 and prevents its downstream gene expression. Thus, these considerable outcomes provide new insights into the neuroprotective effect of glabridin.

Metal Oxide Nanoparticles in Food Packaging and Their Influence on Human Health

It is a matter of common knowledge in the literature that engineered metal oxide nanoparticles have properties that are efficient for the design of innovative food/beverage packages. Although nanopackages have many benefits, there are circumstances when these materials are able to release nanoparticles into the food/beverage matrix. Once dispersed into food, engineered metal oxide nanoparticles travel through the gastrointestinal tract and subsequently enter human cells, where they display various behaviors influencing human health or wellbeing. This review article provides an insight into the antimicrobial mechanisms of metal oxide nanoparticles as essential for their benefits in food/beverage packaging and provides a discussion on the oral route of these nanoparticles from nanopackages to the human body. This contribution also highlights the potential toxicity of metal oxide nanoparticles for human health. The fact that only a small number of studies address the issue of food packaging based on engineered metal oxide nanoparticles should be particularly noted.

TiO2 Nanoparticles and Their Effects on Eukaryotic Cells: A Double-Edged Sword

Nanoparticulate TiO₂ (TiO₂ NPs) is a widely used material, whose potential toxicity towards eukaryotic cells has been addressed by multiple studies. TiO₂ NPs are considered toxic due to their production of reactive oxygen species (ROS), which can, among others, lead to cellular damage, inflammatory responses, and differences in gene expression. TiO₂ NPs exhibited toxicity in multiple organs in animals, generating potential health risks also in humans, such as developing tumors or progress of preexisting cancer processes. On the other hand, the capability of TiO₂ NPs to induce cell death has found application in photodynamic therapy of cancers. In aquatic environments, much has been done in understanding the impact of TiO₂ on bivalves, in which an effect on hemocytes, among others, is reported. Adversities are also reported from other aquatic organisms, including primary producers. These are affected also on land and though some potential benefit might exist when it comes to agricultural plants, TiO₂ can also lead to cellular damage and should be considered when it comes to transfer along the food chain towards human consumers. In general, much work still needs to be done to unravel the delicate balance between beneficial and detrimental effects of TiO₂ NPs on eukaryotic cells.

Neonatal Rat Glia Cultured in Physiological Normoxia for Modeling Neuropathological Conditions In Vitro

Cell culture conditions were proven to highly affect crucial biological processes like proliferation, differentiation, intercellular crosstalk, and senescence. Oxygen tension is one of the major factors influencing cell metabolism and thus, modulating cellular response to pathophysiological conditions. In this context, the presented study aimed at the development of a protocol for efficient culture of rat neonatal glial cells (microglia, astrocytes, and oligodendrocytes) in oxygen concentrations relevant to the nervous tissue. The protocol allows for obtaining three major cell populations, which play crucial roles in sustaining tissue homeostasis and are known to be activated in response to a wide spectrum of external stimuli. The cells are cultured in media without supplement addition to avoid potential modulation of cell processes. The application of active biomolecules for coating culturing surfaces might be useful for mirroring physiological cell interactions with extracellular matrix components. The cell fractions can be assembled as cocultures to further evaluate investigated mechanisms, intercellular crosstalk, or cell response to tested pharmacological compounds. Applying additional procedures, like transient oxygen and glucose deprivation, allows to mimic in vitro the selected pathophysiological conditions. The presented culture system for neonatal rat glial cells is a highly useful tool for in vitro modeling selected neuropathological conditions.

Modulatory Role of Quercetin in Mitochondrial Dysfunction in Titanium Dioxide Nanoparticle-Induced Hepatotoxicity

Background : Titanium dioxide (TiO₂) nanoparticles are among the largely manmade nanomaterials worldwide and are broadly used as both industrial and user products. The primary target site for several nanoparticles is the liver, including TiO₂ nanoparticles (TNPs), exposed directly or indirectly through ingestion of contaminated water, food, or animals and elevated environmental contamination. Oxidative stress is a known facet of nanoparticle-induced toxicity, including TNPs. Mitochondria are potential targets for nanoparticles in several types of toxicity, such as hepatotoxicity. Nevertheless, its causal mechanism is still controversial due to scarcity of literature linking the role of mitochondria-mediated TNP-induced hepatotoxicity. Aim : The objective of the current study was to evaluate the relation of mitochondrial oxidative stress and respiratory chain mechanisms with TNP-induced mitochondrial dysfunction in vitro, and explore the hepatoprotective effect of quercetin (QR), which is a polyphenolic flavonoid abundant in fruits and vegetables with known antioxidant properties, on TNP-induced mitochondrial oxidative stress and disturbance in respiratory chain complex enzymes in the liver of rats. Results: Enzymatic and non-enzymatic antioxidant levels, oxidative stress markers, and mitochondrial complexes were assessed with regard to TNP-induced hepatotoxicity. The depleted lipid peroxidation levels and protein carbonyl content, in mitochondria, induced by TNPs were restored significantly by pretreatment with QR. QR modulated the altered non-enzymatic and enzymatic antioxidants and mitochondrial complex enzymes. Conclusion : Based on the findings, we conclude that QR, which mitigates oxidative stress caused by mitochondrial dysfunction, holds promising capability to potentially diminish TNP-induced adverse effects in the liver.

TGF-β1/SMADs signaling involved in alleviating inflammation induced by nanoparticulate titanium dioxide in BV2 cells

There are increasing safety concerns accompanying the widespread use of nanoparticulate titanium dioxide (nano-TiO₂). It has been demonstrated that nano-TiO₂ can cross the blood-brain barrier and enter the brain, causing damage to the nervous system, consisting mainly of neuroinflammation and neuronal apoptosis. Several studies have linked the TGF-β1/SMADs signaling to the development of inflammatory response in various organs. However, no studies have connected the induction of microglial inflammation by nano-TiO₂ to this signaling. Therefore, this study aimed to investigate the role of TGF-β1/SMADs signaling in microglia inflammatory response induced by nano-TiO₂. The results showed that nano-TiO₂ increased the secretions of pro-inflammatory cytokines (IL-1α, IL-6, and TNF-α) and decreased the expressions of TGF-β1 and SMAD1/2/3 proteins in BV2 cells. When TGF-β1/SMADs signaling was inhibited, the inflammatory effect induced by nano-TiO₂ increased, suggesting a suppressive effect of this signaling on the inflammation. In addition, exogenous TGF-β1 upregulated the expressions of TGF-β1 and SMADs1/2/3 proteins as well as decreased the secretions of pro-inflammatory cytokines (IL-1α, IL-6, and TNF-α) compared to BV2 cells treated with only nano-TiO₂. Our results suggest that nano-TiO₂ may inhibit the TGF-β1/SMADs signaling by suppressing the intracellular secretion of active TGF-β1, leading to microglial activation and the induction or exacerbation of inflammatory responses.

Potential neurotoxicity of titanium implants: Prospective, in-vivo and in-vitro study

Titanium dioxide (TiO₂) is a frequently used biomaterial, particularly in orthopedic and dental implants, and it is considered an inert and benign compound. This has resulted in toxicological scrutiny for TiO₂ in the past decade, with numerus studies showing potential pathologic downstream effects. Herein we describe case report of a 77-year-old male with subacute CNS dysfunction, secondary to breakdown of a titanium-based carotid stent and leading to blood levels 1000 times higher (3 ppm) than the reported normal. We prospectively collected tissues adjacent to orthopedic implants and found a positive correlation between titanium concentration and time of implant in the body (r = 0.67, p < 0.02). Rats bearing titanium implants or intravascularly treated with TiO₂ nanoparticles (TiNP) exhibited memory impairments. A human blood-brain barrier (BBB) in-vitro model exposed to TiNP showed paracellular leakiness, which was corroborated in-vivo with the decrease of key BBB transcripts in isolated blood vessels from hippocampi harvested from TiNP-treated mice. Titanium particles rapidly internalized into brain-like endothelial cells via caveolae-mediated endocytosis and macropinocytosis and induced pro-inflammatory reaction with increased expression of pro-inflammatory genes and proteins. Immune reaction was mediated partially by IL-1R and IL-6. In summary, we show that high levels of titanium accumulate in humans adjacent to orthopedic implants, and our in-vivo and in-vitro studies suggest it may be neurotoxic.

An updated overview on metal nanoparticles toxicity

Although thousands of different nanoparticles (NPs) have been identified and synthesized to date, well-defined, consistent guidelines to control their exposure and evaluate their potential toxicity have yet to be fully established. As potential applications of nanotechnology in numerous fields multiply, there is an increased awareness of the issue of nanomaterials' toxicity among scientists and producers managing them. An updated inventory of customer products containing NPs estimates that they currently number over 5.000; ten years ago, they were one fifth of this. More often than not, products bear no information regarding the presence of NPs in the indicated list of ingredients or components. Consumers are therefore largely unaware of the extent to which nanomaterials have entered our lives, let alone their potential risks. Moreover, the lack of certainties with regard to the safe use of NPs is curbing their applications in the biomedical field, especially in the diagnosis and treatment of cancer, where they are performing outstandingly but are not yet being exploited as much as they could. The production of radical oxygen species is a predominant mechanism leading to metal NPs-driven carcinogenesis. The release of particularly reactive metal ions capable of crossing cell membranes has also been implicated in NPs toxicity. In this review we discuss the origin, behavior and biological toxicity of different metal NPs with the aim of rationalizing related health hazards and calling attention to toxicological concerns involved in their increasingly widespread use.