Systemic immune effects of titanium dioxide nanoparticles after repeated intratracheal instillation in rat

Nanoparticles Targeting Lymph Nodes for Cancer Immunotherapy: Strategies and Influencing Factors

Immunotherapy has emerged as a potent strategy in cancer treatment, with many approved drugs and modalities in the development stages. Despite its promise, immunotherapy is not without its limitations, including side effects and suboptimal efficacy. Using nanoparticles (NPs) as delivery vehicles to target immunotherapy to lymph nodes (LNs) can improve the efficacy of immunotherapy drugs and reduce side effects in patients. In this context, this paper reviews the development of LN-targeted immunotherapeutic NP strategies, the mechanisms of NP transport during LN targeting, and their related biosafety risks. NP targeting of LNs involves either passive targeting, influenced by NP physical properties, or active targeting, facilitated by affinity ligands on NP surfaces, while alternative methods, such as intranodal injection and high endothelial venule (HEV) targeting, have uncertain clinical applicability and require further research and validation. LN targeting of NPs for immunotherapy can reduce side effects and increase biocompatibility, but risks such as toxicity, organ accumulation, and oxidative stress remain, although strategies such as biodegradable biomacromolecules, polyethylene glycol (PEG) coating, and impurity addition can mitigate these risks. Additionally, this work concludes with a future-oriented discussion, offering critical insights into the field.

Quercetin Mitigates Oxidative Stress, Inflammation, Apoptosis, and Histopathological Alterations Induced by Chronic Titanium Dioxide Nanoparticle Exposure in the Rat Spleen

Titanium dioxide nanoparticles (nano-TiO2) have become widespread but are accompanied by various health concerns. Quercetin (QT), a naturally occurring flavonoid in fruits and vegetables, exhibits potent antioxidant properties. This research examined the toxic impacts of nano-TiO2 on the structure and function of the spleen in adult male rats and assessed the possible protective effects of QT. A set of randomly grouped rats was established, consisting of a control group, a QT group (50 mg/kg/day), a nano-TiO2 group (300 mg/kg/day), and a QT-nano-TiO2 group. These substances were orally administered to the respective groups for 90 days. Nano-TiO2 significantly induced oxidative stress in the spleen, leading to reduced levels of serum immunoglobulins. Additionally, there was a notable increase in the expression of apoptotic markers and proinflammatory cytokines. These biochemical disturbances were accompanied by morphological changes in the spleens of rats exposed to nano-TiO2. However, coadministration of QT and nano-TiO2 effectively mitigated most nano-TiO2-induced alterations in the spleen, including apoptotic and proinflammatory responses, antioxidant imbalance, serum immunoglobulin levels, and histopathological changes. It can be concluded that QT has the potential to function as a protective agent against the detrimental impacts of nano-TiO2 on the spleen by improving the antioxidant defense mechanism and modulating the apoptotic and inflammatory responses.

Nano-TiO2 aggravates immunotoxic effects of chronic ammonia stress in zebrafish (Danio rerio) intestine

Ammonia and nano-TiO₂ are commonly found pollutants in aquatic environments around the world. NH₃ has been proved to be absorbed on nano-TiO₂ surface, therefore, the biosafety and environmental effects of ammonia and co-occurring nano-TiO₂ in aquatic environments has increased considerably in recent years. To explore the potential interactive effects and mechanisms of ammonia and nano-TiO₂ on the intestinal immune system, three-month-old female zebrafish were exposed to total ammonia nitrogen (TAN; 0, 3, 30 mg/L) with or without nano-TiO₂ (1 mg/L) for 60 d. The results showed that intestinal ammonia levels increased with the increase of TAN exposure concentration in the presence of nano-TiO₂. Histopathological analysis demonstrated that both TAN and nano-TiO₂ caused cell vacuolation, lymphocyte infiltration and goblet cells hyperplasia in the intestine mucosa. Our study also found that the contents and gene expression levels of lysozyme (lys) and β-defensin (def-β) in the intestine of zebrafish exposed to TAN alone or combined with nano-TiO₂ were significantly reduced, suggesting a decline in the intestinal innate immunity of fish. A broad upregulation of TLRs-related genes indicated that TAN and nano-TiO₂ could activate TLR4/5-mediated MyD88-dependent pathway, and eventually induce intestinal inflammation. It should be noted that TAN combined with nano-TiO₂ had more significant inhibitory effects on the intestinal structure and innate immune responses than TAN alone. Current data suggested that ammonia and nano-TiO₂ had a synergistic inhibitory effect on intestinal mucosal immunity, and their associated health risk to aquatic animals and the water ecosystem should not be underestimated.

Titanium Dioxide Nanoparticles Modulate Systemic Immune Response and Increase Levels of Reduced Glutathione in Mice after Seven-Week Inhalation

Titanium dioxide nanoparticles (TiO₂ NPs) are used in a wide range of applications. Although inhalation of NPs is one of the most important toxicologically relevant routes, experimental studies on potential harmful effects of TiO₂ NPs using a whole-body inhalation chamber model are rare. In this study, the profile of lymphocyte markers, functional immunoassays, and antioxidant defense markers were analyzed to evaluate the potential adverse effects of seven-week inhalation exposure to two different concentrations of TiO₂ NPs (0.00167 and 0.1308 mg TiO₂/m³) in mice. A dose-dependent effect of TiO₂ NPs on innate immunity was evident in the form of stimulated phagocytic activity of monocytes in low-dose mice and suppressed secretory function of monocytes (IL-18) in high-dose animals. The effect of TiO₂ NPs on adaptive immunity, manifested in the spleen by a decrease in the percentage of T-cells, a reduction in T-helper cells, and a dose-dependent decrease in lymphocyte cytokine production, may indicate immunosuppression in exposed mice. The dose-dependent increase in GSH concentration and GSH/GSSG ratio in whole blood demonstrated stimulated antioxidant defense against oxidative stress induced by TiO₂ NP exposure.

Comparative evaluation of gold nanoparticles and Alum as immune enhancers against rabies vaccine and related immune reactivity, physiological, and histopathological alterations: in vivo study

Purpose

The present study aimed to compare the immune-enhancing potential of gold nanoparticles (AuNPs) to Alum against rabies vaccine and the related immunological, physiological, and histopathological effects.

Materials and Methods

Alum and AuNPs sole and in combination with rabies vaccine were used at 0.35 mg/mL and 40 nM/mL, respectively. Rats used were categorized into six groups (20/each): control rats, rabies vaccine, aluminum phosphate gel, rabies vaccine adsorbed to Alum, AuNPs, and rabies vaccine adjuvant AuNPs.

Results

Liver and kidney functions were in the normal range after AuNPs and Alum adjuvanted vaccine compared to control. Interleukin-6 and interferon-γ levels were significantly increased in groups immunized with Alum and AuNPs adjuvanted vaccine, the peak level was in the case of AuNP adjuvanted vaccine on the 14th day. Ninety days post-vaccination, total immunoglobulin G (IgG) against adjuvanted rabies vaccine showed a significantly elevated anti-rabies IgG with AuNPs and Alum adsorbed vaccine compared with unadjuvanted one. The total antioxidant capacity, malondialdehyde (MDA) levels, superoxide dismutase, and glutathione peroxidase activities were significantly increased post-adjuvanted AuNPs adjuvanted vaccine vaccination than in Alum adsorbed vaccine, while MDA was significantly decreased. The histopathological examination revealed detectable alterations post-AuNPs and Alum adjuvanted vaccine immunization compared with liver and kidney profiles post-administration of unadjuvanted and non-immunized groups, meanwhile, splenic tissue revealed hyperplasia of lymphoid follicles indicating increased immune reactivity.

Conclusion

The AuNPs are promising enhancers of the immune response as Alum, and the undesirable effects of AuNPs could be managed by using suitable sizes, shapes, and concentrations.

Assessment of the potential toxic effect of magnetite nanoparticles on the male reproductive system based on immunological and molecular studies

Magnetite nanoparticles (MNPs) are the most conventional type of iron oxide nanoparticles used in the food industrial processes, removal of heavy metals, and biomedical applications in vivo or in vitro. Until now, there is no sufficient information that can confirm its effect on the body's immune system and reproductive health in males. The purpose of this research is to estimate the immunotoxic and reproductive toxic effects of MNPs in male rats. This study included 36 adult male albino rats divided into three groups. The experimental groups were intraperitoneally injected with MNPs at doses of 5 and 10 mg/kg body weight 3 times/week for 60 days, while the control group was injected with saline solution. MNPs caused a significant decrease in the body weight change of the high-treated group. MNPs produced changes in the lymphocyte proliferation rate which referred to a significant immunotoxic effect measured by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-di-phenyltetrazolium bromide reduction method. The testicular tissue of male-treated rats showed some moderate and severe degenerative changes. The sperm parameters of count, motility, and viability were significantly decreased. Sperm morphological abnormalities were detected in all treated animals. MNPs produced a significant decrease in testosterone levels, increased the level of malondialdehyde, impaired the activity of the antioxidant enzymes and induced testicular DNA damage. In conclusion, MNPs affected the normal immune state in male rats and facilitated the generation of reactive oxygen species subsequently triggering testicular oxidative stress damages. All these consequences had a negative impact on male reproductive health.

Copper Oxide Nanoparticles Stimulate the Immune Response and Decrease Antioxidant Defense in Mice After Six-Week Inhalation

Copper oxide nanoparticles (CuO NPs) are increasingly used in various industry sectors. Moreover, medical application of CuO NPs as antimicrobials also contributes to human exposure. Their toxicity, including toxicity to the immune system and blood, raises concerns, while information on their immunotoxicity is still very limited. The aim of our work was to evaluate the effects of CuO NPs (number concentration 1.40×106 particles/cm3, geometric mean diameter 20.4 nm) on immune/inflammatory response and antioxidant defense in mice exposed to 32.5 µg CuO/m3 continuously for 6 weeks. After six weeks of CuO NP inhalation, the content of copper in lungs and liver was significantly increased, while in kidneys, spleen, brain, and blood it was similar in exposed and control mice. Inhalation of CuO NPs caused a significant increase in proliferative response of T-lymphocytes after mitogenic stimulation and basal proliferative activity of splenocytes. CuO NPs significantly induced the production of IL-12p70, Th1-cytokine IFN-γ and Th2-cytokines IL-4, IL-5. Levels of TNF-α and IL-6 remained unchanged. Immune assays showed significantly suppressed phagocytic activity of granulocytes and slightly decreased respiratory burst. No significant differences in phagocytosis of monocytes were recorded. The percentage of CD3+, CD3+CD4+, CD3+CD8+, and CD3-CD19+ cell subsets in spleen, thymus, and lymph nodes did not differ between exposed and control animals. No changes in hematological parameters were found between the CuO NP exposed and control groups. The overall antioxidant protection status of the organism was expressed by evaluation of GSH and GSSG concentrations in blood samples. The experimental group exposed to CuO NPs showed a significant decrease in GSH concentration in comparison to the control group. In summary, our results indicate that sub-chronic inhalation of CuO NPs can cause undesired modulation of the immune response. Stimulation of adaptive immunity was indicated by activation of proliferation and secretion functions of lymphocytes. CuO NPs elicited pro-activation state of Th1 and Th2 lymphocytes in exposed mice. Innate immunity was affected by impaired phagocytic activity of granulocytes. Reduced glutathione was significantly decreased in mice exposed to CuO NPs.

Spatiotemporal Small Non-coding RNAs Expressed in the Germline as an Early Biomarker of Testicular Toxicity and Transgenerational Effects Caused by Prenatal Exposure to Nanosized Particles

In recent years, an apparent decline in human sperm quality has been observed worldwide. One in every 5.5 couples suffers from infertility, with male reproductive problems contributing to nearly 40% of all infertility cases. Although the reasons for the increasing number of infertility cases are largely unknown, both genetic and environmental factors can be contributing factors. In particular, exposure to chemical substances during mammalian male germ cell development has been linked to an increased risk of infertility in later life owing to defective sperm production, reproductive tract obstruction, inflammation, and sexual disorders. Prenatal exposure to nanomaterials (NMs) is no exception. In animal experiments, maternal exposure to NMs has been reported to affect the reproductive health of male offspring. Male germ cells require multiple epigenetic reprogramming events during their lifespan to acquire reproductive capacity. Given that spermatozoa deliver the paternal genome to oocytes upon fertilization, we hypothesized that maternal exposure to NMs negatively affects male germ cells by altering epigenetic regulation, which may in turn affect embryo development. Small non-coding RNAs (including microRNAs, PIWI-interacting RNAs, tRNA-derived small RNAs, and rRNA-derived small RNAs), which are differentially expressed in mammalian male germ cells in a spatiotemporal manner, could play important regulatory roles in spermatogenesis and embryogenesis. Thus, the evaluation of RNAs responsible for sperm fertility is of great interest in reproductive toxicology and medicine. However, whether the effect of maternal exposure to NMs on spermatogenesis in the offspring (intergenerational effects) really triggers multigenerational effects remains unclear, and infertility biomarkers for evaluating paternal inheritance have not been identified to date. In this review, existing lines of evidence on the effects of prenatal exposure to NMs on male reproduction are summarized. A working hypothesis of the transgenerational effects of sperm-derived epigenomic changes in the F1 generation is presented, in that such maternal exposure could affect early embryonic development followed by deficits in neurodevelopment and male reproduction in the F2 generation.

Copper Oxide Nanoparticles Stimulate the Immune Response and Decrease Antioxidant Defense in Mice After Six-Week Inhalation

Copper oxide nanoparticles (CuO NPs) are increasingly used in various industry sectors. Moreover, medical application of CuO NPs as antimicrobials also contributes to human exposure. Their toxicity, including toxicity to the immune system and blood, raises concerns, while information on their immunotoxicity is still very limited. The aim of our work was to evaluate the effects of CuO NPs (number concentration 1.40×10⁶ particles/cm³, geometric mean diameter 20.4 nm) on immune/inflammatory response and antioxidant defense in mice exposed to 32.5 µg CuO/m³ continuously for 6 weeks. After six weeks of CuO NP inhalation, the content of copper in lungs and liver was significantly increased, while in kidneys, spleen, brain, and blood it was similar in exposed and control mice. Inhalation of CuO NPs caused a significant increase in proliferative response of T-lymphocytes after mitogenic stimulation and basal proliferative activity of splenocytes. CuO NPs significantly induced the production of IL-12p70, Th1-cytokine IFN-γ and Th2-cytokines IL-4, IL-5. Levels of TNF-α and IL-6 remained unchanged. Immune assays showed significantly suppressed phagocytic activity of granulocytes and slightly decreased respiratory burst. No significant differences in phagocytosis of monocytes were recorded. The percentage of CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺, and CD3^-CD19⁺ cell subsets in spleen, thymus, and lymph nodes did not differ between exposed and control animals. No changes in hematological parameters were found between the CuO NP exposed and control groups. The overall antioxidant protection status of the organism was expressed by evaluation of GSH and GSSG concentrations in blood samples. The experimental group exposed to CuO NPs showed a significant decrease in GSH concentration in comparison to the control group. In summary, our results indicate that sub-chronic inhalation of CuO NPs can cause undesired modulation of the immune response. Stimulation of adaptive immunity was indicated by activation of proliferation and secretion functions of lymphocytes. CuO NPs elicited pro-activation state of Th1 and Th2 lymphocytes in exposed mice. Innate immunity was affected by impaired phagocytic activity of granulocytes. Reduced glutathione was significantly decreased in mice exposed to CuO NPs.

Nanoparticles as a Tool in Neuro-Oncology Theranostics

The rapid growth of nanotechnology and the development of novel nanomaterials with unique physicochemical characteristics provides potential for the utility of nanomaterials in theranostics, including neuroimaging, for identifying neurodegenerative changes or central nervous system malignancy. Here we present a systematic and thorough review of the current evidence pertaining to the imaging characteristics of various nanomaterials, their associated toxicity profiles, and mechanisms for enhancing tropism in an effort to demonstrate the utility of nanoparticles as an imaging tool in neuro-oncology. Particular attention is given to carbon-based and metal oxide nanoparticles and their theranostic utility in MRI, CT, photoacoustic imaging, PET imaging, fluorescent and NIR fluorescent imaging, and SPECT imaging.

Grape Seed Proanthocyanidin Extract Mitigates Titanium Dioxide Nanoparticle (TiO2-NPs)-Induced Hepatotoxicity Through TLR-4/NF-κB Signaling Pathway

With the progress of nanotechnology, the adverse effects of nanoscale materials are receiving much attention. Inhibition of toll-like receptor 4 (TLR-4)/nuclear factor kappa B (NF-κB) signaling is a hallmark for downregulating the expression of many inflammatory genes implicated in oxidative stress. Therefore, the present study aimed to demonstrate the influence of grape seed proanthocyanidin extract (GSE) on the hepatic TLR-4/ NF-κB signaling pathway in TiO₂-NP-induced liver damage in rats. Forty male Albino rats were divided into 4 groups (n = 10): G1 was used as a control, G2 received TiO₂-NPs (500 mg/kg/day orally) from the 17th to 30th day (acute toxicity), G3 received GSE (75 mg/kg/day orally) for 30 days, and G4 pre- and co-treated with GSE (for 30 days) and TiO₂-NPs (from the 17th to 30th day), with the aforementioned doses. TiO₂-NPs induced severe hepatic injury that was indicated by biochemical alterations in serum liver markers (acetylcholinesterase, ALT, ALP, total proteins, albumin, and direct bilirubin), oxidative stress indicators (MDA, GSH, and catalase), and histopathological alterations as well. Moreover, TiO₂-NPs triggered an inflammatory response via the upregulation of TLR-4, NF-κB, NIK, and TNF-α mRNA expressions. Pre- and co-treatments with GSE alleviated the detrimental effects of TiO₂-NPs which were enforced by the histopathological improvements. These results indicated that GSE effectively protected against TiO₂-NP-induced hepatotoxicity via the inhibition of TLR-4/NF-κB signaling and hence suppressed the production of pro inflammatory cytokines such as TNF-α and improved the antioxidant status of the rats.

The long-term oral exposure to titanium dioxide impaired immune functions and triggered cytotoxic and genotoxic impacts in rats

BACKGROUND

Titanium dioxide "TiO₂, E171″ is a widely used food additive that exists in various everyday food products all over the world together with vast applications in cosmetics and industry. However, many toxicological aspects particularly following oral exposure still unclear.

METHODS

Hence, this study was planned to examine the effect of oral exposure of male Wistar rats to two doses of TiO₂ (20 or 40 mg/kg b.wt.) through oral gavage once daily for 90 consecutive days on the blood components, immunity, cytotoxic, and genotoxic indicators.

RESULTS

A dose-dependent leukopenia, eosinophilia, neutrophilia, and thrombocytopenia were noted. Also, the immunoglobins G (IgG) and IgM were significantly elevated in TiO₂ treated rats. The phagocytic activities, lysozyme, nitric oxide, and immunoglobulin levels were significantly depleted following TiO₂ exposure. A significantly reduced lymphocyte proliferation but elevated LDH activity was prominent in TiO₂ treated rats. Different pathological perturbations were observed in both splenic tissue and bone marrow. A marked increase in CD4⁺ and CD8⁺ immunolabeling was evident. A significant increase in the comet variables was recorded in response to the exposure of rats to the increasing level of TiO₂ at both levels.

CONCLUSION

Overall, these results indicated that TiO₂ could induce hematotoxicity, genotoxic, and immunotoxic alterations with exposure for long durations.

Titanium dioxide nanoparticles induced the apoptosis of RAW264.7 macrophages through miR-29b-3p/NFAT5 pathway

Titanium dioxide nanoparticles (TiO₂ NPs) are widely found in consumer and industrial products, contributing to their prevalent presence in our surroundings. In this study, several miRNAs in the immuno-related pathways were found to be dysregulated in RAW264.7 cells after 24-h exposure to TiO₂ NPs, including miR-29b-3p, which had not been previously found to be associated with the dysregulation of immunity after exposure to TiO₂ NPs. The KEGG pathway and GO enrichment analysis suggested that miR-29b-3p functioned both in the T and B cell receptor signaling pathways. The NFAT5 gene was predicted to regulate miR-29b-3p using the MiRDB online database. The expression of miR-29b-3p and NFAT5 was found to be inversely correlated using qRT-PCR and western blotting analysis. Dual-luciferase reporter gene assays demonstrated the precise regulatory relationship between miR-29b-3p and NFAT5. The upregulation of miR-29b-3p was found to reinforce the apoptosis of cells, while no changes were found in terms of the cell cycle or cell proliferation, using MTT, cell apoptosis, and cycle detection experiments. Our results demonstrate that miR-29b-3p is involved in the response of RAW264.7 cells to exposure to TiO₂, proving evidence for the further study of the toxicity and mechanisms of nano-TiO₂ exposure.

MicroRNA Response and Toxicity of Potential Pathways in Human Colon Cancer Cells Exposed to Titanium Dioxide Nanoparticles

Titanium dioxide nanoparticles (TiO₂-NPs) are widely used for biomedical and food applications, the toxicity of TiO₂-NPs in vivo and in vitro has been elucidated, but the underlying cytotoxicity of TiO₂-NPs against microRNA remains largely unknown. The purpose of this study was to analyze microRNA profiling induced by TiO₂-NPs against NCM460 and HCT116 cell lines. Comparative analysis identified 34 and 24 microRNAs were significantly altered in the TiO₂-NPs treated cells at concentrations of 3 μg/mL and 30 μg/mL, respectively. Functional classification demonstrated that a large proportion of genes involved in metabolism, human disease, and environmental information process were significantly upregulated by TiO₂-NPs. Bioinformatics analysis suggested that microRNA 378 might be an early indicator of cellular response to exogenous stimuli with apoptotic signals. Furthermore, TiO₂-NPs significantly altered the expression of microRNA 378b and 378g in HCT116 and NCM460 cell lines at different concentrations from 3 to 6 μg/mL. These concentrations elicit high-sensitivity of stimuli response in colon cancer cells when exposed to the slight doses of TiO₂-NPs. Our study indicated that microRNAs 378b and 378g may play an important role in TiO₂-NPs-mediated colonic cytotoxicity, which may provide a valuable insight into the molecular mechanisms of potential risks in colitis and colon cancer.

Evaluation of immunologic and intestinal effects in rats administered an E 171-containing diet, a food grade titanium dioxide (TiO2)

The toxicity of dietary E 171, a food grade titanium dioxide was evaluated. A recent study reported rats receiving E 171 in water developed inflammation and aberrant crypt foci (ACF) in the gastrointestinal tract. Here, rats received food containing E 171 (7 or 100 days). The 100-day study included feeding E 171 after dimethylhydrazine (DMH) or vehicle only pretreatment. Food consumption was similar between treatment groups with maximum total cumulative E 171 exposure being 2617 mg/kg in 7 days and 29,400 mg/kg in 100 days. No differences were observed due to E 171 in the percentage of dendritic, CD4+ T or Treg cells within Peyer's patches or the periphery, or in cytokine production in plasma, sections of jejunum, and colon in 7- or 100-day E 171 alone fed rats. Differences were observed for IL-17A in colon (400 ppm E 171 + DMH) and IL-12p70 in plasma (40 ppm E 171 + DMH). E 171 had no effect on histopathologic evaluations of small and large intestines, liver, spleen, lungs, or testes, and no effects on ACF, goblet cell numbers, or colonic gland length. Dietary E 171 administration (7- or 100-day), even at high doses, produced no effect on the immune parameters or tissue morphology.

Metallic Nanoparticles: General Research Approaches to Immunological Characterization

Our immunity is guaranteed by a complex system that includes specialized cells and active molecules working in a spatially and temporally coordinated manner. Interaction of nanomaterials with the immune system and their potential immunotoxicity are key aspects for an exhaustive biological characterization. Several assays can be used to unravel the immunological features of nanoparticles, each one giving information on specific pathways leading to immune activation or immune suppression. Size, shape, and surface chemistry determine the surrounding corona, mainly formed by soluble proteins, hence, the biological identity of nanoparticles released in cell culture conditions or in a living organism. Here, we review the main laboratory characterization steps and immunological approaches that can be used to understand and predict the responses of the immune system to frequently utilized metallic or metal-containing nanoparticles, in view of their potential uses in diagnostics and selected therapeutic treatments.

Short- and long-term gene expression profiles induced by inhaled TiO2 nanostructured aerosol in rat lung

The number of workers potentially exposed to nanoparticles (NPs) during industrial processes is increasing, although the toxicological properties of these compounds still need to be fully characterized. As NPs may be aerosolized during industrial processes, inhalation represents their main route of occupational exposure. Here, the short- and long-term pulmonary toxicological properties of titanium dioxide were studied, using conventional and molecular toxicological approaches. Fischer 344 rats were exposed to 10 mg/m³ of a TiO₂ nanostructured aerosol (NSA) by nose-only inhalation for 6 h/day, 5 days/week for 4 weeks. Lung samples were collected up to 180 post-exposure days. Biochemical and cytological analyses of bronchoalveolar lavage (BAL) showed a strong inflammatory response up to 3 post-exposure days, which decreased overtime. In addition, gene expression profiling revealed overexpression of genes involved in inflammation that was maintained 6 months after the end of exposure (long-term response). Genes involved in oxidative stress and vascular changes were also up-regulated. Long-term response was characterized by persistent altered expression of a number of genes up to 180 post-exposure days, despite the absence of significant histopathological changes. The physiopathological consequences of these changes are not fully understood, but they should raise concerns about the long-term pulmonary effects of inhaled biopersistent NPs such as TiO₂.

The Secretory Response of Rat Peritoneal Mast Cells on Exposure to Mineral Fibers

BACKGROUND

Exposure to mineral fibers is of substantial relevance to human health. A key event in exposure is the interaction with inflammatory cells and the subsequent generation of pro-inflammatory factors. Mast cells (MCs) have been shown to interact with titanium oxide (TiO₂) and asbestos fibers. In this study, we compared the response of rat peritoneal MCs challenged with the asbestos crocidolite and nanowires of TiO₂ to that induced by wollastonite employed as a control fiber.

METHODS

Rat peritoneal MCs (RPMCs), isolated from peritoneal lavage, were incubated in the presence of mineral fibers. The quantities of secreted enzymes were evaluated together with the activity of fiber-associated enzymes. The ultrastructural morphology of fiber-interacting RPMCs was analyzed with electron microscopy.

RESULTS

Asbestos and TiO₂ stimulate MC secretion. Secreted enzymes bind to fibers and exhibit higher activity. TiO₂ and wollastonite bind and improve enzyme activity, but to a lesser degree than crocidolite.

CONCLUSIONS

(1) Mineral fibers are able to stimulate the mast cell secretory process by both active (during membrane interaction) and/or passive (during membrane penetration) interaction; (2) fibers can be found to be associated with secreted enzymes-this process appears to create long-lasting pro-inflammatory environments and may represent the active contribution of MCs in maintaining the inflammatory process; (3) MCs and their enzymes should be considered as a therapeutic target in the pathogenesis of asbestos-induced lung inflammation; and (4) MCs can contribute to the inflammatory effect associated with selected engineered nanomaterials, such as TiO₂ nanoparticles.

Molecular mechanism for miR-350 in regulating of titanium dioxide nanoparticles in macrophage RAW264.7 cells

This study investigated the role of microRNA(miRNA) in regulating the cytotoxicity of TiO₂ nanoparticles (nano-TiO₂) to RAW264.7 cells. RAW264.7 cells were treated with 0 and 100 μg/ml nano-TiO₂ for 24 h (for miRNA analysis). The differentially expressed miRNAs were detected using Illumina HiSeq™ 2000 sequencing. Through the bio-informatics analysis, miR-350 was found to play an important role in multiple signaling pathways, including MAPK signaling pathway, NF-kappa B signaling pathway and Apoptosis. To characterize the miR-350 function, miR-350 mimic was transfected into RAW264.7 cells for 24 h. MTT and Flow Cytometry were performed to detect cell proliferation, apoptosis and cell cycle (repetition), respectively. QRT-PCR, Western Blot methods and Luciferase assays were applied to detect expression of putative target gene PIK3R3. The results showed that miRNA profiles were differentially dysregulated. The apoptosis rate of miR-350 mimic group was significantly higher than negative control group (p < .05). Cell proliferation and cell cycle had no significant differences between treatment and negative control group. Compared with negative control, the level of protein of PIK3R3 was significantly decreased (p < .05), and the expression of 3'UTR constructs of PIK3R3 was significantly decreased (p < .05) in miR-350 mimic group. The expression of miRNAs was changed after exposed to nano-TiO₂, and biological function and target gene results showed miR-350 may promote RAW264.7 cell apoptosis through the negative regulation of PIK3R3 gene. Our results could provide a basis for further understanding of toxicity and possible mechanisms of nano-TiO₂ exposure.

Molecular and immunological toxic effects of nanoparticles

Nanoparticles have emerged as a boon for the public health applications such as drug delivery, diagnostic, and imaging. Biodegradable and non-bio degradable nanoparticles have been used at a large scale level to increase the efficiency of the biomedical process at the cellular, animal and human level. Exponential use of nanoparticles reinforces the adverse immunological changes at the human health level. Physical and chemical properties of nanoparticles often lead to a variety of immunotoxic effects such as activation of stress-related genes, membrane disruption, and release of pro-inflammatory cytokines. Delivered nanoparticles in animal or human interact with various components of the immune system such as lymphocytes, macrophages, neutrophils etc. Nanoparticles delivered above the threshold level damages the cellular physiology by the generation of reactive oxygen and nitrogen species. This review article represents the potential of nanoparticles in the field of nanomedicine and provides the critical evidence which leads to develop immunotoxicity in living cells and organisms by altering immunological responses.

Immunological mechanism of low-dose priming radiation resistance in walker-256 tumor model mice

The aim of the present study was to investigate whether low-dose priming radiation induces antitumor immunity that can be augmented by the modulation of natural killer (NK) cell and cytokine activity using a mouse tumor model. Walker-256 cells were injected into the right flank of male BALB/c mice. At 7 days after inoculation, mice were divided into three groups, including group 1,2,3. In group 1 the mice were without radiation, in group 2 the mice were received 2 Gy radiation only, and in group 3 the mice were radiated with a priming dose of 75 mGy followed by 2 Gy radiation after 24 h. On day 21 following the radiation, the tumors were removed and the tumor index (tumor weight as a percentage of body weight) was calculated. At 1, 7, 14 and 21 days following the 2 Gy radiation, mouse splenocytes were isolated to analyze the NK activity and measure the production of the cytokines interleukin-1β, interferon-γ and tumor necrosis factor-α by ELISA. Apoptosis was also measured by flow cytometry. The results demonstrated that priming radiation significantly delayed the tumor growth and prolonged the median survival time to 38 days compared with the 31-day survival in the 2 Gy radiation group. The percentage of apoptotic cells was significantly higher in the mice that received 75 mGy + 2 Gy radiation compared with that in the mice that received 2 Gy alone; by contrast, mice that were not irradiated exhibited a relatively low level of apoptosis. The primed mice had a higher level of NK activity as compared with the mice exposed to 2 Gy radiation only or mice that were not irradiated. Furthermore, cytokine expression remained at a higher level in mice receiving priming dose of radiation compared that in the mice receiving only 2 Gy radiation. In conclusion, the results indicated that low-dose priming X-ray radiation may enhance the NK activity and the levels of cytokines, and that the immune response serves an important role in anticancer therapy, including radiotherapy.

Toxicity of titanium dioxide nanoparticles: Effect of dose and time on biochemical disturbance, oxidative stress and genotoxicity in mice

The toxic impact of titanium dioxide nanoparticles (TiO₂NPs) on human health is of prime importance owing to their wide uses in many commercial industries. In the present study, the effect of different doses and exposure time durations of TiO₂NPs (21nm) inducing oxidative stress, biochemical disturbance, histological alteration and cytogenetic aberration in mice liver and bone marrow was investigated. Different doses of (TiO₂NPs) (50, 250 and 500mg/kg body weight) were each daily intrapertioneally injected to mice for 7, 14 and 45days. Aspartate and alanine aminotransferases (AST &ALT), gamma glutamyl transpeptidase (GGT), total protein, total antioxidant capacity (TAC), malondialdehyde (MDA), glutathione (GSH), catalase (CAT) and nitric oxide (NO) levels were measured. The work was extended to evaluate the liver histopathological pattern and the chromosomal aberration in mice spinal cord bone marrow. The results revealed severe TiO₂NPs toxicity in a dose and time dependent manner with positive correlation (r=0.98) for most investigated biochemical parameters. The same observation was noticed for the histological analysis. In case of cytogenetic study, chromosomal aberrations were demonstrated after injection of TiO₂NPs with 500mg/kg b. wt. for 45days. In conclusion, the selected biochemical parameters and the liver architectures were influenced with dose and time of TiO₂NPs toxicity, while the genetic disturbance started at the high dose of exposure and for long duration. Further studies are needed to fulfil the effect of TiO₂NPs on pharmaceutical and nutritional applications.

Progress of in vivo studies on the systemic toxicities induced by titanium dioxide nanoparticles

Titanium dioxide nanoparticles (TiO2 NPs) are inorganic materials with a diameter of 1-100 nm. In recent years, TiO2 NPs have been used in a wide range of products, including food, toothpaste, cosmetics, medicine, paints and printing materials, due to their unique properties (high stability, anti-corrosion, and efficient photocatalysis). Following exposure via various routes including inhalation, injection, dermal deposition and gastrointestinal tract absorption, NPs can be found in various organs in the body potentially inducing toxic effects. Thus more attention to the safety of TiO2 NPs is necessary. Therefore, the present review aims to provide a comprehensive evaluation of the toxic effects induced by TiO2 NPs in the lung, liver, stomach, intestine, kidney, spleen, brain, hippocampus, heart, blood vessels, ovary and testis of mice and rats in in vivo experiments, and evaluate their potential toxic mechanisms. The findings will provide an important reference for human risk evaluation and management following TiO2 NP exposure.

Interaction of New-Developed TiO₂-Based Photocatalytic Nanoparticles with Pathogenic Microorganisms and Human Dermal and Pulmonary Fibroblasts

TiO₂-based photocatalysts were obtained during previous years in order to limit pollution and to ease human daily living conditions due to their special properties. However, obtaining biocompatible photocatalysts is still a key problem, and the mechanism of their toxicity recently received increased attention. Two types of TiO₂ nanoparticles co-doped with 1% of iron and nitrogen (TiO₂-1% Fe–N) atoms were synthesized in hydrothermal conditions at pH of 8.5 (HT1) and 5.5 (HT2), and their antimicrobial activity and cytotoxic effects exerted on human pulmonary and dermal fibroblasts were assessed. These particles exhibited significant microbicidal and anti-biofilm activity, suggesting their potential application for microbial decontamination of different environments. In addition, our results demonstrated the biocompatibility of TiO₂-1% Fe–N nanoparticles at low doses on lung and dermal cells, which may initiate oxidative stress through dose accumulation. Although no significant changes were observed between the two tested photocatalysts, the biological response was cell type specific and time- and dose-dependent; the lung cells proved to be more sensitive to nanoparticle exposure. Taken together, these experimental data provide useful information for future photocatalytic applications in the industrial, food, pharmaceutical, and medical fields.

Toxicity of Nano-Titanium Dioxide (TiO2-NP) Through Various Routes of Exposure: a Review

Nano-titanium dioxide (TiO2) is one of the most commonly used materials being synthesized for use as one of the top five nanoparticles. Due to the extensive application of TiO2 nanoparticles and their inclusion in many commercial products, the increased exposure of human beings to nanoparticles is possible. This exposure could be routed via dermal penetration, inhalation and oral ingestion or intravenous injection. Therefore, regular evaluation of their potential toxicity and distribution in the bodies of exposed individuals is essential. Keeping in view the potential health hazards of TiO2 nanoparticles for humans, we reviewed the research articles about studies performed on rats or other mammals as animal models. Most of these studies utilized the dermal or skin and the pulmonary exposures as the primary routes of toxicity. It was interesting that only very few studies revealed that the TiO2 nanoparticles could penetrate through the skin and translocate to other tissues, while many other studies demonstrated that no penetration or translocation could happen through the skin. Conversely, the TiO2 nanoparticles that entered through the pulmonary route were translocated to the brain or the systemic circulation from where these reached other organs like the kidney, liver, etc. In most studies, TiO2 nanoparticles appeared to have caused oxidative stress, histopathological alterations, carcinogenesis, genotoxicity and immune disruption. Therefore, the use of such materials in humans must be either avoided or strictly managed to minimise risks for human health in various situations.

Titanium nanoparticle inhalation induces renal fibrosis in mice via an oxidative stress upregulated transforming growth factor-β pathway

Titanium dioxide nanoparticles (Nano-TiO2) are gradually being used extensively in clinical settings, industry, and daily life. Accumulation studies showed that Nano-TiO2 exposure is able to cause injuries in various animal organs, including the lung, liver, spleen, and kidney. However, it remains unclear whether exposure of Nano-TiO2 by inhalation causes renal fibrosis. Here, we investigated the role of reactive oxygen species (ROS)/reactive nitrogen species (RNS) related signaling molecules in chronic renal damage after Nano-TiO2 inhalation in mice. Mice were treated with Nano-TiO2 (0.1, 0.25, and 0.5 mg/week) or microparticle-TiO2 (0.5 mg/week) by nonsurgical intratracheal instillation for 4 weeks. The results showed that Nano-TiO2 inhalation increased renal pathological changes in a dose-dependent manner. No renal pathological changes were observed in microparticle-TiO2-instilled mice. Nano-TiO2 (0.5 mg/week) possessed the ability to precipitate in the kidneys, determined by transmission electron microscopy and increased serum levels of blood urea nitrogen. The expressions of markers of ROS/RNS and renal fibrosis markers, including nitrotyrosine, inducible nitric oxide synthase, hypoxia inducible factor-1α (HIF-1α), heme oxygenase 1, transforming growth factor-β (TGFβ), and collagen I, determined by immunohistochemical staining were increased in the kidneys. Furthermore, Nano-TiO2-induced renal injury could be mitigated by iNOS inhibitor aminoguanidine and ROS scavenger N-acetylcysteine treatment in transcription level. The in vitro experiments showed that Nano-TiO2 significantly and dose-dependently increased the ROS production and the expressions of HIF-1α and TGFβ in human renal proximal tubular cells, which could be reversed by N-acetylcysteine treatment. Taken together, these results suggest Nano-TiO2 inhalation might induce renal fibrosis through a ROS/RNS-related HIF-1α-upregulated TGF-β signaling pathway.