Crystalline silica-induced pulmonary inflammation and autoimmunity in mature adult NZBW/f1 mice: age-related sensitivity and impact of omega-3 fatty acid intervention.

OBJECTIVE: Occupational exposure to respirable crystalline silica (cSiO2) has been linked to lupus development. Previous studies in young lupus-prone mice revealed that intranasal cSiO2 exposure triggered autoimmunity, preventable with docosahexaenoic acid (DHA). This study explores cSiO2 and DHA effects in mature lupus-prone adult mice, more representative of cSiO2-exposed worker age. METHODS: Female NZBWF1 mice (14-week old) were fed control (CON) or DHA-supplemented diets. After two weeks, mice were intranasally instilled saline (VEH) or 1 mg cSiO2 weekly for four weeks. Cohorts were then analyzed 1- and 5-weeks postinstillation for lung inflammation, cell counts, chemokines, histopathology, B- and T-cell infiltration, autoantibodies, and gene signatures, with results correlated to autoimmune glomerulonephritis onset. RESULTS: VEH/CON mice showed no pathology. cSiO2/CON mice displayed significant ectopic lymphoid tissue formation in lungs at 1 week, increasing by 5 weeks. cSiO2/CON lungs exhibited elevated cellularity, chemokines, CD3+ T-cells, CD45R + B-cells, IgG + plasma cells, gene expression, IgG autoantibodies, and glomerular hypertrophy. DHA supplementation mitigated all these effects. DISCUSSION: The mature adult NZBWF1 mouse used here represents a life-stage coincident with immunological tolerance breach and one that more appropriately represents the age (20-30 yr) of cSiO2-exposed workers. cSiO2-induced robust pulmonary inflammation, autoantibody responses, and glomerulonephritis in mature adult mice, surpassing effects observed previously in young adults. DHA at a human-equivalent dosage effectively countered cSiO2-induced inflammation/autoimmunity in mature mice, mirroring protective effects in young mice. CONCLUSION: These results highlight life-stage significance in this preclinical lupus model and underscore omega-3 fatty acids' therapeutic potential against toxicant-triggered autoimmune responses.

State of the Art of Silica Nanoparticles: An Overview on Biodistribution and Preclinical Toxicity Studies.

Over the past few years, nanoparticles have drawn particular attention in designing and developing drug delivery systems due to their distinctive advantages like improved pharmacokinetics, reduced toxicity, and specificity. Along with other successful nanosystems, silica nanoparticles (SNPs) have shown promising effects for therapeutic and diagnostic purposes. These nanoparticles are of great significance owing to their modifiable surface with various ligands, tunable particle size, and large surface area. The rate and extent of degradation and clearance of SNPs depend on factors such as size, shape, porosity, and surface modification, which directly lead to varying toxic mechanisms. Despite SNPs' enormous potential for clinical and pharmaceutical applications, safety concerns have hindered their translation into the clinic. This review discusses the biodistribution, toxicity, and clearance of SNPs and the formulation-related factors that ultimately influence clinical efficacy and safety for treatment. A holistic view of SNP safety will be beneficial for developing an enabling SNP-based drug product.

Silicon dioxide nanoparticles suppress copper toxicity in Mentha arvensis L. by adjusting ROS homeostasis and antioxidant defense system and improving essential oil production.

Copper (Cu) is an essential micronutrient for plants; however, the excessive accumulation of Cu due to various anthropogenic activities generates progressive pollution of agricultural land and that causes a major constraint for crop production. Excess Cu (80 mg kg-1) in the soil diminished growth and biomass, photosynthetic efficiency and essential oil (EO) content in Mentha arvensis L., while amplifying the antioxidant enzyme's function and reactive oxygen species (ROS) production. Therefore, there is a pressing need to explore effective approaches to overcome Cu toxicity in M. arvensis plants. Thus, the present study unveils the potential of foliar supplementation of two distinct forms of silicon dioxide nanoparticles (SiO2 NPs) i.e., Aerosil 200F and Aerosil 300 to confer Cu stress tolerance attributes to M. arvensis. The experiment demonstrated that applied forms of SiO2 NPs (120 mg L-1), enhanced plants' growth and augmented the photosynthetic efficiency along with the activities of CA (carbonic anhydrase) and NR (nitrate reductase), however, the effects were more accentuated by Aerosil 200F application. Supplementation of SiO2 NPs also exhibited a beneficial effect on the antioxidant machinery of Cu-disturbed plants by raising the level of proline and total phenol as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR), thereby lowering ROS and electrolytic leakage (EL). Interestingly, SiO2 NPs supplementation upscaled EO production in Cu-stressed plants with more pronounced effects received in the case of Aerosil 200F over Aerosil 300. We concluded that the nano form (Aerosil 200F) of SiO2 proved to be the best in improving the Cu-stress tolerance in plants.

Mitochondrial folate pathway regulates myofibroblast differentiation and silica-induced pulmonary fibrosis.

BACKGROUND: Silica-induced pulmonary fibrosis (silicosis) is a diffuse interstitial fibrotic disease characterized by the massive deposition of extracellular matrix in lung tissue. Fibroblast to myofibroblast differentiation is crucial for the disease progression. Inhibiting myofibroblast differentiation may be an effective way for pulmonary fibrosis treatment. METHODS: The experiments were conducted in TGF-ß treated human lung fibroblasts to induce myofibroblast differentiation in vitro and silica treated mice to induce pulmonary fibrosis in vivo. RESULTS: By quantitative mass spectrometry, we revealed that proteins involved in mitochondrial folate metabolism were specifically upregulated during myofibroblast differentiation following TGF-ß stimulation. The expression level of proteins in mitochondrial folate pathway, MTHFD2 and SLC25A32, negatively regulated myofibroblast differentiation. Moreover, plasma folate concentration was significantly reduced in patients and mice with silicosis. Folate supplementation elevated the expression of MTHFD2 and SLC25A32, alleviated oxidative stress and effectively suppressed myofibroblast differentiation and silica-induced pulmonary fibrosis in mice. CONCLUSION: Our study suggests that mitochondrial folate pathway regulates myofibroblast differentiation and could serve as a potential target for ameliorating silica-induced pulmonary fibrosis.

Baicalin alleviates silica-induced lung inflammation and fibrosis by inhibiting TLR4/NF-?B pathway in rats.

Silicosis is an occupational lung disease caused by inhaling silica dust. The disease is characterized by early lung inflammation and late irreversible pulmonary fibrosis. Here we report the effect of Baicalin, a main flavonoid compound from the roots of Chinese herbal medicine Huang Qin on silicosis in a rat model. Results showed Baicalin (50 or 100 mg/kg/day) can mitigate the silica-induced lung inflammation and reduce the harm of alveolar structure and the blue region of collagen fibers in rat lung at 28 days after administration. At the same time, Baicalin also diminished the level of interleukin-1beta (IL-1beta, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) in lung tissues. The protein expression of collagen I (Col-1), alpha-smooth muscle actin (alpha-SMA) and vimentin were down-regulated while E-cadherin (E-cad) was increased in Baicalin-treated rats. In addition, the Toll Like Receptor 4 (TLR4)/ nuclear factor kappaB (NF-kappaB) pathway was enabled at 28 days after silica infusion, and the treatment of Baicalin diminished the expression of TLR4 and NF-?B in the lungs of rat with silicosis. These results suggested that Baicalin inhibited the pulmonary inflammatory and fibrosis in a rat model of silicosis, which could be attributed to inhibition of the TLR4/NF-kappaB pathway.

Enhancement of suppression oxidative stress and inflammation of quercetin by nano-decoration for ameliorating silica-induced pulmonary fibrosis.

Silicosis is a life-threatening lung fibrotic disease caused by excessive inhalation of environmental exposure to crystalline silica-containing dust, whereas achieving therapeutic cures are constrained. Antioxidation and anti-inflammation are currently recognized as effective strategies to counteract organ fibrosis. Using naturally occurring phytomedicines quercetin (Qu) has emerged in antagonizing fibrotic disorders involving oxidative stress and inflammation, but unfortunately the hydrophilicity deficiency. Herein, chitosan-assisted encapsulation of Qu in nanoparticles (Qu/CS-NPs) was first fabricated for silicosis-associated fibrosis treatment by pulmonary delivery. Qu/CS-NPs with spherical diameters of ~160 nm, demonstrated a high Qu encapsulated capability, excellent hydrophilic stability, fantastic oxidation radical scavenging action, and outstanding controlled as well as slow release Qu action. A silicosis rat model induced by intratracheal instillation silica was established to estimate the anti-fibrosis effect of Qu/CS-NPs. After intratracheal administration, CS-NPs markedly enhanced Qu anti-fibrotic therapy efficacy, accompanying the evident changes in reducing ROS and MDA production to mitigate oxidative stress, inhibiting IL-1ß and TNF-α release, improving lung histological architecture, down-regulating α-SAM levels and suppressing ECM deposition, and thereby ameliorating silica-induced pulmonary fibrosis. Results manifested that the augmented antioxidant and anti-inflammatory activities of Qu by CS-NPs delivery was a result of achieving this remarkable improvement in curative effects. Combined with negligible systemic toxicity, nano-decorated Qu may provide a feasible therapeutic option for silicosis therapy.

Yangqing Chenfei formula attenuates silica-induced pulmonary fibrosis by suppressing activation of fibroblast via regulating PI3K/AKT, JAK/STAT, and Wnt signaling pathway.

BACKGROUND: Yangqing Chenfei formula (YCF) has been demonstrated its clinical efficiency on silicosis patients. However, the effect of YCF against silicotic fibrosis and its mechanism remain unclear. PURPOSE: This study is aimed to investigate active compounds and molecular mechanism of YCF in treating silicosis. METHOD: YCF was orally administrated to silicosis rats induced by crystalline silica. The effective fraction of YCF and the compounds was isolated and identified by using macroporous resin and HPLC-MS, respectively. The targets and potential molecular mechanism of YCF against silicotic fibrosis were investigated through pharmacological network and RNA-sequencing analysis and in vitro-experimental validation. RESULTS: YCF could remarkably improve the lung function and pathological changes of silicotic rats, reduce the aggregation of fibrocytes and deposition of ECM, such as collagen I, III, FN, and α-SMA, and suppress the TGF-ß/Smad3 signaling. Furthermore, YCF6, the effective fraction derived from YCF, could significantly inhibit fibroblast activation induced by TGF-ß. Then, 135 compounds were identified from YCF6 by using HPLC-MS, and Network pharmacology analysis predicted total 941 targets for these compounds. Moreover, 409 differentially expressed genes of fibroblast activation induced by TGF-ß were identified. Then, integrated analysis of the 941 targets with 409 differentially expressed genes showed that YCF6 contains multiple compounds, such as tangeretin, L-Malic acid, 2-Monolinolein etc., which inhibits fibroblast activation probably by targeting different proteins, such as PIK3CA, AKT1, JAK2, STAT3, GSK3ß, leading to regulate the signal network, such as PI3K/AKT signaling pathway, JAK/STAT signaling pathway, and Wnt signaling pathway. Finally, in vitro experiment indicated that tangeretin, the active compound contained in YCF6, could significantly inhibit TGF-ß induced fibroblast activation. Moreover, YCF6 and tangeretin could markedly inhibit the activation of PI3K/AKT, JAK/STAT, and Wnt pathway. CONCLUSION: YCF contained multiple compounds and targeted various proteins that regulated the fibroblast activation, which might be the molecular mechanisms of it in treating silicosis.

Lipid dysregulation associated with progression of silica-induced pulmonary fibrosis.

Silicosis is an irreversible, progressive, fibrotic lung disease caused by long-term exposure to dust-containing silica particles at the workplace. Despite the precautions enforced, the rising incidence of silicosis continues to occur globally, particularly in developing countries. A better understanding of the disease progression and potential metabolic reprogramming of silicosis is warranted. The low- or high-dose silica-induced pulmonary fibrosis in mice was constructed to mimic chronic or accelerated silicosis. Silica-induced mice lung fibrosis was analyzed by histology, lung function, and computed tomography scans. Non-targeted metabolomics of the lung tissues was conducted by ultra-high-performance liquid chromatography-mass spectrometry to show the temporal metabolic trajectory. The low-dose silica-induced silicosis characterized inflammation for up to 42 days, with the onset of cellular silicon nodules. Conversely, the high-dose silica-induced silicosis characterized inflammation for up to 14 days, after which the disease developed rapidly, with a large volume of collagen deposition, presenting progressive massive fibrosis. Both low- and high silica-induced fibrosis had aberrant lipid metabolism. Combined with the RNA-Seq data, this multiomics study demonstrated alterations in the enzymes involved in sphingolipid metabolism. Time-dependent metabolic reprogramming revealing abnormal glycerophospholipid metabolism was intimately associated with the process of inflammation, whereas sphingolipid metabolism was crucial during lung fibrosis. These findings suggest that lipid dysregulation, especially sphingolipid metabolism, was involved in the process of silicosis.

Physical Obstruction of Nasal Cavities With Subsequent Asphyxia, Causes Lethality of Rats in an Acute Inhalation Study With Hydrophobic HMDZ Surface-Treated Synthetic Amorphous Silica (SAS).

The aim of the present study was to understand the mechanism of lethality associated with high dose inhalation of a low-density hydrophobic surface-treated SAS observed in some acute inhalation studies. It was demonstrated that physical obstruction of the upper respiratory tract (nasal cavities) caused the effects observed. Hydrophobic surface-treated SAS was inhaled (flow-past, nose-only) by six Wistar rats (three males and three females) in an acute toxicity study at a concentration of ~500 mg/m3 for an intended 4-hr exposure. Under the conditions of the test set-up, the concentration applied was found to be the highest that can be delivered to the test animal port without significant alteration of the aerosol size distribution over time. None of the test- material-exposed animals survived the planned observation time of 4 h; three animals died between 2 34 h after starting exposure and cessation of exposure at 3 14 h, two died after transfer to their cages and the remaining animal was sacrificed due to its poor condition and welfare considerations. Histology accomplished by energy dispersive X-ray (EDX) analysis demonstrated that test material particles agglomerated and formed a gel-like substrate that ultimately blocked the upper respiratory airways, which proved fatal for the rat as an obligatory nose breather. This observation is in line with the findings reported by Hofmann et al. showing a correlation between lethality and hydrophobicity determined by contact angle measurement. The aerosol characterizations associated with this study are provided in detail by Wessely et al.

Pyrogenic synthetic amorphous silica (NM-203): Genotoxicity in rats following sub-chronic oral exposure.

The genotoxicity of nano-structured synthetic amorphous silica (SAS), a common food additive, was investigated in vivo in rats. A 90-day oral toxicity study was performed according to OECD test guideline 408 and the genotoxicity of pyrogenic SAS nanomaterial NM-203 was assessed in several organs, using complementary tests. Adult Sprague-Dawley rats of both sexes were treated orally for 90 days with 0, 2, 5, 10, 20, or 50 mg SAS/kg bw per day. Dose levels were selected to approximate expected human dietary exposures to SAS. DNA strand breaks were evaluated by the comet assay in blood, bone marrow, liver, and spleen according to OECD test guideline 489; mutations induced in bone marrow precursors of erythrocytes were assessed by the Pig-a assay and chromosome/ genome damage by the micronucleus assay in blood (OECD test guideline 474) and colon. No treatment-related increases of gene (Pig-a) or chromosome/genome (micronucleus) mutations were detected in the blood. The percentage of micronucleated cells was not increased in the colon of treated rats. Among the organs analyzed by the comet assay, the spleen was the only target showing a weak but biologically relevant genotoxic effect.

Exploration study on serum metabolic profiles of Chinese male patients with artificial stone silicosis, silicosis, and coal worker's pneumoconiosis.

Long-term exposure to inhaled silica dust induces pneumoconiosis, which remains a heavy burden in developing countries. Modern industry provides new resources of occupational SiO2 leading to artificial stone silicosis especially in developed countries. This study aimed to characterize the serum metabolic profile of pneumoconiosis and artificial stone silicosis patients. Our case-control study recruited 46 pairs of pneumoconiosis patients and dust-exposed workers. Nontargeted metabolomics and lipidomics by ultra-high-performance liquid chromatography-tandem mass spectrometry platform were conducted to characterize serum metabolic profile in propensity score-matched (PSM) pilot study. 54 differential metabolites were screened, 24 of which showed good screening efficiency through receiver operating characteristics (ROC) in pilot study and validation study (both AUC > 0.75). 4 of the 24 metabolites can predict pneumoconiosis stages, which are 1,2-dioctanoylthiophosphatidylcholine, phosphatidylcholine(O-18:1/20:1), indole-3-acetamide and l-homoarginine. Kynurenine, N-tetradecanoylsphingosine 1-phosphate, 5-methoxytryptophol and phosphatidylethanolamine(22:6/18:1) displayed the potential as specific biomarkers for artificial stone silicosis. Taken together, our results confirmed that tryptophan metabolism is closely related to pneumoconiosis and may be related to disease progression. Hopefully, our results could supplement the biomarkers of pneumoconiosis and provide evidence for the discovery of artificial stone silicosis-specific biomarkers.

Nicotinamide Mononucleotide Ameliorates Silica-Induced Lung Injury through the Nrf2-Regulated Glutathione Metabolism Pathway in Mice.

Nicotinamide mononucleotide (NMN) is a natural antioxidant approved as a nutritional supplement and food ingredient, but its protective role in silicosis characterized by oxidative damage remains unknown. In this study, we generated a silicosis model by intratracheal instillation of silica, and then performed histopathological, biochemical, and transcriptomic analysis to evaluate the role of NMN in silicosis. We found that NMN mitigated lung damage at 7 and 28 days, manifested as a decreasing coefficient of lung weight and histological changes, and alleviated oxidative damage by reducing levels of reactive oxygen species and increasing glutathione. Meanwhile, NMN treatment also reduced the recruitment of inflammatory cells and inflammatory infiltration in lung tissue. Transcriptomic analysis showed that NMN treatment mainly regulated immune response and glutathione metabolism pathways. Additionally, NMN upregulated the expression of antioxidant genes Gstm1, Gstm2, and Mgst1 by promoting the expression and nuclear translocation of nuclear factor-erythroid 2 related factor 2 (Nrf2). Gene interaction analysis showed that Nrf2 interacted with Gstm1 and Mgst1 through Gtsm2. Promisingly, oxidative damage mediated by these genes occurred mainly in fibroblasts. In summary, NMN alleviates silica-induced oxidative stress and lung injury by regulating the endogenous glutathione metabolism pathways. This study reveals that NMN supplementation might be a promising strategy for mitigating oxidative stress and inflammation in silicosis.

Apigenin exerts chemopreventive effects on lung injury induced by SiO2 nanoparticles through the activation of Nrf2.

Apigenin (APG) is a flavonoid widely distributed in fruits, vegetables, and herbs, with comprehensive pharmacological effects. In this paper, we report that APG can elicit a protective effect, which is comparable to those induced by gymnoside II/n-BuOH extracts of Bletilla striata, on SiO2-induced lung injury in vitro and in vivo. In vitro experiments showed that APG (25 µM) could restore the SiO2-decreased A549 cell viability and lower the apoptotic rate and the production of intracellular reactive oxygen species (ROS) in A549 cells treated with nm SiO2. Western blot results showed that APG (25 µM) could increase the level of Nuclear factor E2-related factor 2 (Nrf2) and its downstream proteins. In vivo experiments showed that APG (20 mg/kg) could potently alleviate the SiO2-elicited lung injury by enhancing the Nrf2 expression and thereby suppressing Bax/Bcl-2 pathway. The present study suggests that APG can significantly alleviate the SiO2-induced lung injury both in vitro and in vivo through, at least partially, activating Nrf2 expression.

MicroSPECT Imaging-Guided Treatment of Idiopathic Pulmonary Fibrosis in Mice with a Vimentin-Targeting 99mTc-Labeled N-Acetylglucosamine-Polyethyleneimine.

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic disease with poor prognosis. Evidence has shown that vimentin is a key regulator of lung fibrogenesis. 99mTc-labeled N-acetylglucosamine-polyethyleneimine (NAG-PEI), a vimentin-targeting radiotracer, was used for the early diagnosis of IPF, and NAG-PEI was also used as a therapeutic small interfering RNA (siRNA) delivery vector for the treatment of IPF in this study. Single-photon emission-computed tomography (SPECT) imaging of bleomycin (BM)- and silica-induced IPF mice with 99mTc-labeled NAG-PEI was performed to visualize pulmonary fibrosis and monitor the treatment efficiency of siRNA-loaded NAG-PEI, lipopolysaccharide (LPS, a tolerogenic adjuvant), or zymosan (ZYM, an immunostimulant). The lung uptakes of 99mTc-NAG-PEI in the BM- and silica-induced IPF mice were clearly and directly correlated with IPF progression. The lung uptake of 99mTc-NAG-PEI in the NAG-PEI/TGF-ß1-siRNA treatment group or LPS treatment group was evidently lower than that in the control group, while the lung uptake of 99mTc-NAG-PEI was significantly higher in the ZYM treatment group compared to that in the control group. These results demonstrate that NAG-PEI is a potent MicroSPECT imaging-guided theranostic platform for IPF diagnosis and therapy.

Triiodothyronine ameliorates silica-induced pulmonary inflammation and fibrosis in mice.

Environmental exposure to silica or particles is very common in natural, agricultural and industrial activities. Chronic silica exposure can lead to silicosis, which remains one of the most serious interstitial lung diseases all through the world, while viable therapeutic choices are restricted. Triiodothyronine (T3) has been shown to exert a defensive role in many pulmonary diseases, however, rare data are available regarding the role of T3 on silica-induced injury. We constructed an experimental silicosis mouse model and T3 was intraperitoneally administrated after instillation of silica to observe the effect of T3 on silica-induced lung inflammation and fibrosis. Our results showed that the silicosis mouse model was accompanied by changes in thyroid morphology and function, and T3 supplement reduced silica-induced lung damage, inflammation and collagen deposition. The protective properties of T3 on silica-induced lung injury could be partially mediated through thyroid hormone receptors. And the mechanism by which T3 treatment ameliorated silica-induced fibrosis appeared to be via the reduction of glycolysis. Also, T3 could sufficiently postpone the progression of pulmonary fibrosis in established silicosis. Our findings reveal that administration of T3 could down-regulate the inflammatory response, pulmonary fibrosis and other lung damage caused by silica. The reduction of glycolysis may be one of the mechanisms.

Genome-Wide DNA Methylation Alterations and Potential Risk Induced by Subacute and Subchronic Exposure to Food-Grade Nanosilica in Mice.

The intensive application of nanomaterials in the food industry has raised concerns about their potential risks to human health. However, limited data are available on the biological safety of nanomaterials in food, especially at the epigenetic level. This study examined the implications of two types of synthetic amorphous silica (SAS), food-grade precipitated silica (S200) and fumed silica Aerosil 200F (A200F), which are nanorange food additives. After 28-day continuous and intermittent subacute exposure to these SAS via diet, whole-genome methylation levels in mouse peripheral leukocytes and liver were significantly altered in a dose- and SAS type-dependent manner, with minimal toxicity detected by conventional toxicological assessments, especially at a human-relevant dose (HRD). The 84-day continuous subchronic exposure to all doses of S200 and A200F induced liver steatosis where S200 accumulated in the liver even at HRD. Genome-wide DNA methylation sequencing revealed that the differentially methylated regions induced by both SAS were mainly located in the intron, intergenic, and promoter regions after 84-day high-dose continuous exposure. Bioinformatics analysis of differentially methylated genes indicated that exposure to S200 or A200F may lead to lipid metabolism disorders and cancer development. Pathway validation experiments indicated both SAS types as potentially carcinogenic. While S200 inhibited the p53-mediated apoptotic pathway in mouse liver, A200F activated the HRAS-mediated MAPK signaling pathway, which is a key driver of hepatocarcinogenesis. Thus, caution must be paid to the risk of long-term exposure to food-grade SAS, and epigenetic parameters should be included as end points during the risk assessment of food-grade nanomaterials.

Omega-3 Polyunsaturated Fatty Acid Intervention Against Established Autoimmunity in a Murine Model of Toxicant-Triggered Lupus.

Workplace exposure to respirable crystalline silica dust (cSiO2) has been etiologically linked to the development of lupus and other human autoimmune diseases. Lupus triggering can be recapitulated in female NZBWF1 mice by four weekly intranasal instillations with 1 mg cSiO2. This elicits inflammatory/autoimmune gene expression and ectopic lymphoid structure (ELS) development in the lung within 1 week, ultimately driving early onset of systemic autoimmunity and glomerulonephritis. Intriguingly, dietary supplementation with docosahexaenoic acid (DHA), an ω-3 polyunsaturated fatty acid (PUFA) found in fish oil, beginning 2 week prior to cSiO2 challenge, prevented inflammation and autoimmune flaring in this novel model. However, it is not yet known how ω-3 PUFA intervention influences established autoimmunity in this murine model of toxicant-triggered lupus. Here we tested the hypothesis that DHA intervention after cSiO2-initiated intrapulmonary autoimmunity will suppress lupus progression in the NZBWF1 mouse. Six-week old NZWBF1 female mice were fed purified isocaloric diet for 2 weeks and then intranasally instilled with 1 mg cSiO2 or saline vehicle weekly for 4 consecutive weeks. One week after the final instillation, which marks onset of ELS formation, mice were fed diets supplemented with 0, 4, or 10 g/kg DHA. One cohort of mice (n = 8/group) was terminated 13 weeks after the last cSiO2 instillation and assessed for autoimmune hallmarks. A second cohort of mice (n = 8/group) remained on experimental diets and was monitored for proteinuria and moribund criteria to ascertain progression of glomerulonephritis and survival, respectively. DHA consumption dose-dependently increased ω-3 PUFA content in the plasma, lung, and kidney at the expense of the ω-6 PUFA arachidonic acid. Dietary intervention with high but not low DHA after cSiO2 treatment suppressed or delayed: (i) recruitment of T cells and B cells to the lung, (ii) development of pulmonary ELS, (iii) elevation of a wide spectrum of plasma autoantibodies associated with lupus and other autoimmune diseases, (iv) initiation and progression of glomerulonephritis, and (v) onset of the moribund state. Taken together, these preclinical findings suggest that DHA supplementation at a human caloric equivalent of 5 g/d was an effective therapeutic regimen for slowing progression of established autoimmunity triggered by the environmental toxicant cSiO2.

Panax ginseng modulates oxidative stress, DNA damage, apoptosis, and inflammations induced by silicon dioxide nanoparticles in rats.

Silicon dioxide nanoparticles (SiO2 NPs) are extensively used in cosmetics, food, and drug delivery. The main mechanism of SiO2 NPs toxicities depends on oxidative stress. Ginseng (Panax ginseng Meyer) is used in various medicinal applications because of its antioxidant efficiency. Therefore, the present study was carried out to investigate the possible combated role of ginseng against SiO2 NPs toxicity in rat liver. Thirty-five male rats (160-180 g) were allocated into five groups of seven rats each, randomly. The first group was used as a control while groups 2, 3, 4, and 5 were treated orally with ginseng (Gin; 75 mg/kg, 1/10 LD50 ), SiO2 NPs, (200 mg/kg, 1/10 LD50 ), Gin + SiO2 NPs (protection group), and SiO2 NPs + Gin (therapeutic group) for 5 weeks, respectively. Treatment with SiO2 NPs increased lipid peroxidation, liver function enzymes, and decreased antioxidant enzymes (SOD, CAT, GPx, GST) activity and non-enzymatic antioxidant (GSH) level. SiO2 NPs administration motivated liver apoptosis as revealed by the upregulation of the apoptotic genes, Bcl2-associated x protein (Bax), and Beclin 1 and downregulation of the anti-apoptotic gene, B-cell lymphoma 2 (Bcl2) as well as increase in DNA damage. Also, SiO2 NPs administration caused inflammation as indicated by upregulation of the inflammation-related genes (interleukin 1 beta [IL1ß], tumor necrosis factor-alpha [TNFα], nuclear factor kappa B [NFκB], cyclooxygenase 2 [Cox2], transforming growth factor-beta 1 [TGFß1]) as well as cell cycle arrest in the G0/G1 phase of liver cells. Moreover, histopathological examination proved the biochemical and molecular perturbations occurred due to SiO2 NPs toxicity. On the other hand, ginseng caused a significant modulation on the deleterious effects induced by SiO2 NPs in rat liver. In conclusion, ginseng has a potent preventive effect than the therapeutic one and might be used in the treatment of SiO2 NPs hepatotoxicity.

The effect of short silica fibers (0.3 µm 3.2 µm) on macrophages.

Silica fibers with a dimension of 0.3 µm ∙ 3.2 µm2 nm were prepared by a modified Stöber synthesis as model particles. The particles were characterized by scanning electron microscopy, elemental analysis, thermogravimetry and X-ray powder diffraction. Their uptake by macrophages (THP-1 cells and NR8383 cells) was studied by confocal laser scanning microscopy and scanning electron microscopy. The uptake by cells was very high, but the silica fibers were not harmful to NR8383 cells in concentrations up to 100 µg mL-1. Only above 100 µg mL-1, significant cell toxic effects were observed, probably induced by a high dose of particles that had sedimented on the cells and led to the adverse effects. The chemotactic response as assessed by the particle-induced migration assay (PICMA) was weak in comparison to a control of agglomerated silica particles. The as-prepared fibers were fully X-ray amorphous but crystallized to ß-cristobalite after heating to 1000 °C and converted to α-cristobalite upon cooling to ambient temperature. The fibers had sintered to larger aggregates but retained their elongated primary shape. The particle cytotoxicity towards THP-1 cells was not significantly enhanced by the crystallization.

n-BuOH extract of Bletilla striata exerts chemopreventive effects on lung against SiO2 nanoparticles through activation of Nrf2 pathway.

BACKGROUND: SiO2 nanoparticles (nm SiO2) are ubiquitous in daily life and are acknowledged to be detrimental to human health. Bletilla striata is a traditional medicine used for generations in China and its polysaccharide has the anti-pulmonary fibrosis effect. PURPOSE: To investigate the lung protective effect of the small molecules (n-BuOH extract) of B. striata and clarify the underlying mechanism. STUDY DESIGN AND METHODS: C57BL/6 mice were subjected to intratracheal instillation with nm SiO2 nanoparticle suspension (7 mg/kg) to construct the in vivo model of nm SiO2-induced lung injury. The chemical profile of the n-BuOH extract of B. striata was investigated by HPLC analysis using authentic samples isolated from B. striata. Gymnoside II with the most potent chemoprotective capacity in the n-BuOH extract was used to clarify the potential bio-active molecular basis of the n-BuOH extract using in vitro experiments. The cytotoxicity, apoptosis, oxidative stress, and the Nrf2 signaling pathway were examined in SiO2-induced A549 cells. ML385 was adopted to down-regulate the Nrf2 expression. RESULTS: The n-BuOH extract of B. striata (40 mg/kg) could alleviate the SiO2-induced lung injury by increasing Nrf2 expression and thereby suppressing Bax/Bcl-2 pathway in the nm SiO2-induced mice model. The chemical profile study showed that militarine, gymnoside II, and 4-allyl-2, 6-dimethoxyphenol glucoside were the main constituents of n-BuOH extract. Studies on gymnoside II revealed that it could partially restore the SiO2-induced decline in cell viability while did not affect the growth of normal A549 cells within the concentration range of 1-50 µM, suggesting a protective effect against nm SiO2 in lung A549 cells. The hoechst 33258 staining, flow cytometry, and western blot experiments demonstrated that gymnoside II (25 µM) could partially reverse the SiO2-induced cell apoptosis and ROS production by enhancing Nrf2, HO-1, and γ-GCSc expressions and Nrf2 silencing by ML385 abrogated the effects of gymnoside II (25 µM) on apoptosis and ROS production in A549 cells. CONCLUSION: The present study suggests that in addition to the polysaccharide, small molecules (n-BuOH extract) of B. striata can also elicit a protective effect on lung injuries through the Nrf2-dependent mechanism and gymnoside II is one of the main bio-active constituents contributing to the n-BuOH extract-elicited lung protective effect against nm SiO2.