3-nitrotyrosine and titanium-dioxide

Substrate nanoscale topography influences cell proliferation and differentiation through mechanisms that are at present poorly understood. In particular the molecular mechanism through which cells 'sense' and adapt to the substrate and activate specific intracellular signals, influencing cells survival and behavior, remains to be clarified.. To characterize these processes at the molecular level we studied the differentiation of PC12 cells on nanostructured TiO2 films obtained by supersonic cluster beam deposition.Our findings indicate that, in PC12 cells grown without Nerve Growth Factor (NGF), the roughness of nanostructured TiO2 triggers neuritogenesis by activating the expression of nitric oxide synthase (NOS) and the phospho-extracellular signal-regulated kinase 1/2 (pERK1/2) signaling. Differentiation is associated with an increase in protein nitration as observed in PC12 cells grown on flat surfaces in the presence of NGF. We demonstrate that cell differentiation and protein nitration induced by topography are not specific for PC12 cells but can be regarded as generalized effects produced by the substrate on different neuronal-like cell types, as shown by growing the human neuroblastoma SH-SY5Y cell line on nanostructured TiO2.. Our data provide the evidence that the nitric oxide (NO) signal cascade is involved in the differentiation process induced by nanotopography, adding new information on the mechanism and proteins involved in the neuritogenesis triggered by the surface properties.

Topics: Animals; Biocompatible Materials; Cell Differentiation; Cell Proliferation; Gene Expression Regulation; Humans; Mechanotransduction, Cellular; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Nerve Growth Factor; Neurites; Nitric Oxide; Nitric Oxide Synthase Type II; PC12 Cells; Rats; Surface Properties; Titanium; Tyrosine

Titanium is widely used clinically, yet little is known regarding the effects of modifying its three-dimensional surface geometry at the nanoscale level. In this project we have explored the in vivo response in terms of nitric oxide scavenging and fibrotic capsule formation to nano-modified titanium implant surfaces. We compared titanium dioxide (TiO(2)) nanotubes with 100 nm diameters fabricated by electrochemical anodization with TiO(2) control surfaces. Significantly lower nitric oxide was observed for the nanostructured surface in solution, suggesting that nanotubes break down nitric oxide. To evaluate the soft tissue response in vivo TiO(2) nanotube and TiO(2) control implants were placed in the rat abdominal wall for 1 and 6 weeks. A reduced fibrotic capsule thickness was observed for the nanotube surfaces for both time points. Significantly lower nitric oxide activity, measured as the presence of nitrotyrosine (P<0.05), was observed on the nanotube surface after 1 week, indicating that the reactive nitrogen species interaction is of importance. The differences observed between the titanium surfaces may be due to the catalytic properties of TiO(2), which are increased by the nanotube structure. These findings may be significant for the interaction between titanium implants in soft tissue as well as bone tissue and provide a mechanism by which to improve future clinical implants.

Topics: Animals; Cell Count; Fibrosis; Implants, Experimental; Macrophages; Male; Nanotubes; Nitric Oxide; Organ Specificity; Rats; Rats, Sprague-Dawley; Silicon Dioxide; Surface Properties; Titanium; Tyrosine

We have shown that pulmonary nanoparticle exposure impairs endothelium dependent dilation in systemic arterioles. However, the mechanism(s) through which this effect occurs is/are unclear. The purpose of this study was to identify alterations in the production of reactive species and endogenous nitric oxide (NO) after nanoparticle exposure, and determine the relative contribution of hemoproteins and oxidative enzymes in this process. Sprague-Dawley rats were exposed to fine TiO2 (primary particle diameter approximately 1 microm) and TiO2 nanoparticles (primary particle diameter approximately 21 nm) via aerosol inhalation at depositions of 4-90 microg per rat. As in previous intravital experiments in the spinotrapezius muscle, dose-dependent arteriolar dilations were produced by intraluminal infusions of the calcium ionophore A23187. Nanoparticle exposure robustly attenuated these endothelium-dependent responses. However, this attenuation was not due to altered microvascular smooth muscle NO sensitivity because nanoparticle exposure did not alter arteriolar dilations in response to local sodium nitroprusside iontophoresis. Nanoparticle exposure significantly increased microvascular oxidative stress by approximately 60%, and also elevated nitrosative stress fourfold. These reactive stresses coincided with a decreased NO production in a particle deposition dose-dependent manner. Radical scavenging, or inhibition of either myeloperoxidase or nicotinamide adenine dinucleotide phosphate oxidase (reduced) oxidase partially restored NO production as well as normal microvascular function. These results indicate that in conjunction with microvascular dysfunction, nanoparticle exposure also decreases NO bioavailability through at least two functionally distinct mechanisms that may mutually increase local reactive species.

Topics: Animals; Calcimycin; Capillaries; Dose-Response Relationship, Drug; Endothelium, Vascular; Inhalation Exposure; Lung; Male; Nanoparticles; Nitric Oxide; Nitric Oxide Donors; Nitroprusside; Oxidative Stress; Particle Size; Rats; Rats, Sprague-Dawley; Signal Transduction; Titanium; Tyrosine; Vasodilation

Protein tyrosine nitration is a prevalent post-translational modification which occurs as a result of oxidative and nitrative stress, it may be directly involved in the onset and/or progression of diseases. Considering the existence of nano titanium dioxide (TiO(2)) in environment and sunscreen products along with the high content of nitrite in sweat, the UV-exposed skin may be a significant target for the photosensitized damage. In this paper, tyrosine nitration of bovine serum albumin (BSA) was initiated in the UV-irradiated reaction mixture containing 0.2-3.0mg/ml of three commercially nano TiO(2) products and 0.25-1.0mM NO2-. It was found that anatase TiO(2) and Degussa P25 TiO(2) showed prominent photocatalytic activity on promoting the formation of protein tyrosine nitration, and the optimum condition for the reaction was around physiological pH. Meanwhile, the photocatalytic effect of rutile on protein tyrosine nitration was subtle. The potential physiological significance of nano TiO(2)-photocatalytic protein nitration was also demonstrated in mouse skin homogenate. Although the relationship between photocatalytic protein tyrosine nitration and chronic cutaneous diseases needs further study, the toxicity of nano TiO(2) to the skin disease should be paid more attention in the production and utilization process.

Topics: Animals; Antioxidants; Catalysis; Cattle; Environment; Mice; Nanostructures; Nitrites; Oxidative Stress; Protein Processing, Post-Translational; Serum Albumin, Bovine; Skin; Skin Diseases; Sunscreening Agents; Titanium; Tyrosine; Ultraviolet Rays

Anatase particles of titanium dioxide (TiO2) absorb ultraviolet (UV) light which is shorter than 415 nm. Photoexcited TiO2, a strong oxidizer, is expected to inhibit malignant cell growth. Liposomes accelerate endophagocytosis to the cytoplasm of encapsulated materials. In this study, we examined anti-tumor effects of TiO2 and liposome-encapsulated TiO2 (LT) with UVA irradiation by an air pouch cancer model using NBT-II bladder cancer cells, which simulates bladder cancer. Injection of TiO2 or LT into the air pouch was followed by UVA irradiation via the opened pouch. Tumors of TiO2 + UVA and LT + UVA groups showed more pronounced necrotic areas, apoptotic indices, nitrotyrosine formation, tumor growth inhibition and increased survival compared with control groups. Especially the LT + UVA group showed more remarkable anti-tumoral effects than the TiO2 + UVA group, which was associated with higher TiO2 incorporation. These findings suggest that LT might be more effective than noncoated TiO2 in the treatment of bladder cancer.

Topics: Animals; Cell Line, Tumor; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Liposomes; Male; Mice; Mice, Nude; Oxidative Stress; Photochemotherapy; Photosensitizing Agents; Titanium; Tyrosine; Urinary Bladder Neoplasms