Purification and sidewall functionalization of multiwalled carbon nanotubes and resulting bioactivity in two macrophage models

Abstract

This study examined the consequences of surface carboxylation of multiwalled carbon nanotubes (MWCNT) on bioactivity. Since commercial raw MWCNT contain impurities that may affect their bioactivity, HCl refluxing was exploited to purify raw “as-received” MWCNT by removing the amorphous carbon layer on the MWCNT surface and reducing the metal impurities (e.g. Ni). The removal of amorphous carbon layer was confirmed by Raman spectroscopy and thermogravimetric analysis. Furthermore, the HCl-purified MWCNT provided more available reaction sites, leading to enhanced sidewall functionalization. The sidewall of HCl-purified MWCNT was further functionalized with the –COOH moiety by HNO₃ oxidation. This process resulted in four distinct MWCNT: raw, purified, –COOH-terminated raw MWCNT, and –COOH-terminated purified MWCNT. Freshly isolated alveolar macrophages from C57Bl/6 mice were exposed to these nanomaterials to determine the effects of the surface chemistry on the bioactivity in terms of cell viability and inflammasome activation. Inflammasome activation was confirmed using inhibitors of cathepsin B and Caspase-1. Purification reduced the cell toxicity and inflammasome activation slightly compared to raw MWCNT. In contrast, functionalization of MWCNT with the –COOH group dramatically reduced the cytotoxicity and inflammasome activation. Similar results were seen using THP-1 cells supporting their potential use for high-throughput screening. This study demonstrated that the toxicity and bioactivity of MWCNT were diminished by removal of the Ni contamination and/or addition of –COOH groups to the sidewalls.     

Single-walled carbon nanotubes and graphene oxides induce autophagosome accumulation and lysosome impairment in primarily cultured murine peritoneal macrophages

The wide application of carbon nanomaterials in various fields urges in-depth understanding of the toxic effects and underlying mechanisms of these materials on biological systems. Cell autophagy was recently recognized as an important lysosome-based pathway of cell death, and autophagosome accumulation has been found to be associated with the exposure of various nanoparticles, but the underlying mechanisms are still uncertain due to the fact that autophagosome accumulation can result from autophagy induction and/or autophagy blockade. In this study, we first evaluated the toxicity of acid-functionalized single-walled carbon nanotubes and graphene oxides, and found that both carbon nanomaterials induced adverse effects in murine peritoneal macrophages, and GOs were more potent than AF-SWCNTs. Both carbon nanomaterials induced autophagosome accumulation and the conversion of LC3-I to LC3-II. However, degradation of the autophagic substrate p62 protein was also inhibited by both nanomaterials. Further analyses on lysosomes revealed that both carbon nanomaterials accumulated in macrophage lysosomes, leading to lysosome membrane destabilization, which indicates reduced autophagic degradation. The effects of AF-SWCNTs and GOs on cell autophagy revealed by this study may shed light on the potential toxic mechanism and suggest caution on their utilization.     

Dexamethasone alleviate allergic airway inflammation in mice by inhibiting the activation of NLRP3 inflammasome

Dexamethasone (DEX) is the mainstay treatment for asthma, which is a common chronic airway inflammation disease. However, the mechanism of DEX resolute symptoms of asthma is not completely clear. Here, we aimed to analyze the effect of DEX on airway inflammation in OVA-induced mice and whether this effect is related to the inhibition of the activation of NLRP3 inflammasome. Female (C57BL/6) mice were used to establish the allergic airway inflammation model by inhalation OVA. The number of inflammatory cells in the bronchi alveolar lavage fluid (BALF) was counted by Swiss-Giemsa staining, and the contents of IL-1β, IL-18, IL-5 and IL-17 were detected by ELISA. The degree of inflammatory cells infiltration and mucous cells proliferation in lung tissue were separately observed by H&E and PAS staining. The proteins expression of NLRP3, pro-caspase-1, caspase-1, IL-1β, IL-6 and IL-17 in lung tissue were detected by Western blotting. We found that DEX significantly inhibited OVA-induced inflammatory cells infiltration, airway mucus secretion and goblet cell proliferation in mice. The total and classified numbers of inflammatory cells and the levels of IL-1β, IL-18, IL-5 and IL-17 in the BALF of the experimental group were significantly lower than those of the model group after DEX treatment. DEX also significantly inhibited the activity of NLRP3 inflammasome and reduced the protein contents of Pro-Caspase-1, Caspase-1, Capase-1/Pro-Caspase-1, IL-1β, IL-6 and IL-17 in lung tissues. Our study suggested that DEX alleviates allergic airway inflammation by inhibiting the activity of NLRP3 inflammasome and the levels of IL-1β and IL-18.     

Glyburide attenuates ozone‐induced pulmonary inflammation and injury by blocking the NLRP3 inflammasome

Glyburide is a classic antidiabetic drug that is dominant in inflammation regulation, but its specific role in ozone‐induced lung inflammation and injury remains unclear. In order to investigate whether glyburide prevents ozone‐induced pulmonary inflammation and its mechanism, C57BL/6 mice were intratracheally pre‐instilled with glyburide or the vehicle 1 hour before ozone (1 ppm, 3 hours) or filtered air exposure. After 24 hours, the total inflammatory cells and total protein in bronchoalveolar lavage fluid (BALF) were detected. The pathological alternations in lung tissues were evaluated by HE staining. The expression of NLRP3, interleukin‐1β (IL‐1β), and IL‐18 protein in lung tissues was detected by immunohistochemistry. Western blotting was used to examine the levels of caspase‐1 p10 and active IL‐1β protein. Levels of IL‐1β and IL‐18 in BALF were measured using ELISA kits. Glyburide treatment decreased the total cells in BALF, the inflammatory score, and the mean linear intercept induced by ozone in lung tissues. In addition, glyburide inhibited the expression of NLRP3, IL‐18, and IL‐1β protein in lung tissues, and also suppressed NLRP3 inflammasome activation, including caspase‐1 p10, active IL‐1β protein in lung tissues, IL‐1β, and IL‐18 in BALF. These results demonstrate that glyburide effectively attenuates ozone‐induced pulmonary inflammation and injury via blocking the NLRP3 inflammasome.     

Genotoxicity and carcinogenicity risk of carbon nanotubes

Novel materials are often commercialized without a complete assessment of the risks they pose to human health because such assessments are costly and time-consuming; additionally, sometimes the methodology needed for such an assessment does not exist. Carbon nanotubes have the potential for widespread application in engineering, materials science and medicine. However, due to the needle-like shape and high durability of multiwalled carbon nanotubes (MWCNTs), concerns have been raised that they may induce asbestos-like pathogenicity when inhaled. Indeed, experiments in rodents supported this hypothesis. Notably, the genetic alterations in MWCNT-induced rat malignant mesothelioma were similar to those induced by asbestos. Single-walled CNTs (SWCNTs) cause mitotic disturbances in cultured cells, but thus far, there has been no report that SWCNTs are carcinogenic. This review summarizes the recent noteworthy publications on the genotoxicity and carcinogenicity of CNTs and explains the possible molecular mechanisms responsible for this carcinogenicity. The nanoscale size and needle-like rigid structure of CNTs appear to be associated with their pathogenicity in mammalian cells, where carbon atoms are major components in the backbone of many biomolecules. Publishing adverse events associated with novel materials is critically important for alerting people exposed to such materials. CNTs still have a bright future with superb economic and medical merits. However, appropriate regulation of the production, distribution and secondary manufacturing processes is required, at least to protect the workers.     

A review on benefits of quercetin in hyperuricemia and gouty arthritis

Hyperuricemia becomes a public health problem worldwide. It is not only a major risk factor for gout but also associated with the development of life-threatening diseases such as chronic kidney disease and cardiovascular diseases. Although there are several available therapeutic drugs, some serious adverse effects and contraindications are concerned. These drive the search for an alternative therapy that is effective and safe. Quercetin is of particular interesting since it has been reported numerous pharmacological activities, especially anti-hyperuricemia, antioxidant, anti-inflammation and amelioration of metabolic syndromes and cardiovascular diseases which are comorbidities of hyperuricemia and gout. In addition, quercetin has been widely used as a health supplement for many diseases however, the use for hyperuricemia and gout has not been indicated. Therefore, this review aims to gather and summarize published data regarding the efficacy in preclinical and clinical studies along with possible mechanism of action, and safety aspect of quercetin in order to support the use of quercetin as a dietary supplement for prevention and management of hyperuricemia and gouty arthritis and/or use as alternative or combination therapy to minimize the side effects of the conventional drugs.     

Enalapril inhibits tubulointerstitial inflammation and NLRP3 inflammasome expression in BSA-overload nephropathy of rats

Aim:

Proteinuria is not only a common marker of renal disease, but also involved in renal tubulointerstitial inflammation and fibrosis. The aim of this study was to investigate the mechanisms underlying the protective effects of enalapril, an ACEI, against nephropathy in rats.

Methods:

Wistar rats underwent unilateral right nephrectomy, and then were treated with BSA (5 g·kg⁻¹·d⁻¹, ip), or BSA plus enalapril (0.5 g·kg⁻¹·d⁻¹, po) for 9 weeks. The renal lesions were evaluated using histology and immunohistochemistry. The expression of NLRP3, caspase-1, IL-1β and IL-18 was analyzed using immunohistochemistry, RT-PCR and Western blot.

Results:

BSA-overload resulted in severe proteinuria, which peaked at week 7, and interstitial inflammation with prominent infiltration of CD68⁺ cells (macrophages) and CD3⁺ cells (T lymphocytes), particularly of CD20⁺ cells (B lymphocytes). BSA-overload markedly increased the expression of NLRP3, caspase-1, IL-1β and IL-18 in the proximal tubular epithelial cells, and in inflammatory cells as well. Furthermore, the expression of IL-1β or IL-18 was significantly correlated with proteinuria (IL-1β: r=0.757; IL-18: r=0.834). These abnormalities in BSA-overload rats were significantly attenuated by concurrent administration of enalapril.

Conclusion:

Enalapril exerts protective effects against BSA-overload nephropathy in rats via suppressing NLRP3 inflammasome expression and tubulointerstitial inflammation.     

益母草碱抑制NLRP3炎症小体过度激活调控巨噬细胞M1/M2表型分化

目的 研究益母草碱对脂多糖(LPS)诱导小鼠腹腔巨噬细胞免疫应答影响及相关机制.方法 分离小鼠腹腔巨噬细胞,用脂多糖和益母草碱预处理24 h,MMT法检测巨噬细胞活性;Griess法检测NO释放量;ELISA法检测IL-1β、IL-18、IL-6、TNF-α的释放量;RT-PCR法检测NLRP3、ASC、caspase...     

Characterization of the proteome and lipidome profiles of human lung cells after low dose and chronic exposure to multiwalled carbon nanotubes

The effects of long-term chronic exposure of human lung cells to multi-walled carbon nanotubes (MWCNT) and their impact upon cellular proteins and lipids were investigated. Since the lung is the major target organ, an in vitro normal bronchial epithelial cell line model was used. Additionally, to better mimic exposure to manufactured nanomaterials at occupational settings, cells were continuously exposed to two non-toxic and low doses of a MWCNT for 13-weeks. MWCNT-treatment increased ROS levels in cells without increasing oxidative DNA damage and resulted in differential expression of multiple anti- and pro-apoptotic proteins. The proteomic analysis of the MWCNT-exposed cells showed that among more than 5000 identified proteins; more than 200 were differentially expressed in the treated cells. Functional analyses revealed association of these differentially regulated proteins to cellular processes such as cell death and survival, cellular assembly, and organization. Similarly, shotgun lipidomic profiling revealed accumulation of multiple lipid classes. Our results indicate that long-term MWCNT-exposure of human normal lung cells at occupationally relevant low-doses may alter both the proteome and the lipidome profiles of the target epithelial cells in the lung.     

Potential in vitro effects of carbon nanotubes on human aortic endothelial cells

Respiratory exposure of mice to carbon nanotubes induces pulmonary toxicity and adverse cardiovascular effects associated with atherosclerosis. We hypothesize that the direct contact of carbon nanotubes with endothelial cells will result in dose-dependent effects related to altered cell function and cytotoxicity which may play a role in potential adverse pulmonary and cardiovascular outcomes. To test this hypothesis, we examined the effects of purified single- and multi-walled carbon nanotubes (SWCNT and MWCNT) on human aortic endothelial cells by evaluating actin filament integrity and VE-cadherin distribution by fluorescence microscopy, membrane permeability by measuring the lactate dehydrogenase (LDH) release, proliferation/viability by WST-1 assay, and overall functionality by tubule formation assay. Marked actin filament and VE-cadherin disruption, cytotoxicity, and reduced tubule formation occurred consistently at 24 h post-exposure to the highest concentrations [50-150 μg/10⁶ cells (1.5-4.5 μg/ml)] for both SWCNT and MWCNT tested in our studies. These effects were not observed with carbon black exposure and carbon nanotube exposure in lower concentrations [1-10 μg/10⁶ cells (0.04-0.4 μg/ml)] or in any tested concentrations at 3 h post-exposure. Overall, the results indicate that SWCNT and MWCNT exposure induce direct effects on endothelial cells in a dose-dependent manner.     

Translocation and extra pulmonary toxicities of multi wall carbon nanotubes in rats

This study evaluated the ability of the multi wall carbon nanotubes (MWCNT) to induce extra pulmonary toxicities in rats following intra-tracheal (IT) instillation of two MWCNT. Two carbon nanoparticles were instilled into the lungs of rats (0.2, 1, and 5?mg/kg b.w.) and at different post-exposure intervals, blood and organs like liver, kidney, etc. were collected. The histopathological examination of liver tissues revealed a dose-dependent periportal lymphocytic infiltration, ballooning, foamy degeneration, and necrosis at all post-instillation periods. However, examination of kidney revealed the tubular necrosis and interstitial nephritis with 5?mg/kg dose at 1 month of post-instillation of both MWCNT. These liver and kidney toxicities were further confirmed by the elevated levels of respective tissue damage biomarkers. These results suggest the extra pulmonary toxicities of these carbon nanoparticles might be due to the translocation into the liver and kidney.     

乳铁蛋白治疗牙周炎的炎症免疫机制研究

目的 研究乳铁蛋白调节炎症免疫反应在治疗牙周炎中的作用及其机制。方法 取100只SD大鼠随机分成空白对照组,模型组,乳铁蛋白给药组低、中、高剂量组(1,2,3 g·kg^-1),甲硝唑阳性对照组(0.02 g·kg^-1),PDTC组(200 mg·kg^-1),乳铁蛋白+PDTC组(2 g·kg^-1,200 mg·kg^-1),MCC950组(1 mg·kg^-1),乳铁蛋白+MCC950(2 g·kg^-1,1 mg·kg^-1),每组10只。采用丝线结扎联合10%蔗糖饮水建立模型后开始给药,每天1次口腔给药,空白对照组和模型组口腔给药0.9% NaCl,连续给药1个月后处死各组大鼠。ELISA试剂盒检测IL-1b、IL-8、IL-10的含量;Western blotting检测TLR2-NF-κB通路和NLRP3炎症小体相关蛋白的表达。采用HE染色观察各组大鼠牙周组织的病理变化。结果 与模型组比较,乳铁蛋白各剂量组牙周炎症状得到明显改善,HE染色显示炎症细胞浸润减少,成纤维细胞增生活跃。TLR2、NF-κB、NLRP3、Caspase-1 p20和GSDMD-N蛋白表达降低,促炎因子IL-1b、IL-8的含量降低,抗炎因子IL-10的含量升高。结论 乳铁蛋白在治疗牙周炎中发挥的调节炎症免疫反应可能通过下调TLR2-NF-κB-NLRP3通路的蛋白表达,降低炎症反应的启动和炎症因子的释放,从而达到抗炎的目的。     

白藜芦醇对急性肝损伤小鼠NLRP3炎性体表达的影响

目的观察白藜芦醇对急性肝损伤(acute liver injury,ALI)小鼠Nod样受体家族3(Nod-like receptor 3,NLRP3)炎性体表达的影响,探讨白藜芦醇对ALI的保护作用及其机制。方法本实验采用四氯化碳制作ALI小鼠模型。将雄性ICR小鼠随机分成正常对照组、模型组、白藜芦醇低、中、高剂量组及阳性对照组,每组7只。白藜芦醇低、中、高剂量组及阳性对照组于造模前24 h及1 h分别腹腔注射剂量为10、20及30 mg/kg的白藜芦醇或剂量为100 mg/kg的乙酰半胱氨酸,对照组及模型组在相应时间点腹腔注射等量生理盐水,造模时模型组及各药物干预组采用腹腔注射5%四氯化碳,对照组腹腔注射等量橄榄油。采用蛋白质印迹(Western blot,WB)法测定小鼠肝组织NLRP3、凋亡相关微粒蛋白(apoptosis-associated speck-like protein contain,ASC)、炎性半胱天冬酶-1(caspase-1)蛋白,酶联免疫吸附测定(enzyme linked immunosorbent assay,ELISA)法检测炎症因子白介素(interleukin,IL)-1β及IL-18,全自动生化分析仪测定小鼠肝功能,病理组织学观察肝脏损伤情况及其程度。结果模型组小鼠谷丙转氨酶(alanine aminotransferase,ALT)及谷草转氨酶(aspartate aminotransferase,AST)水平高于正常对照组(P<0.01);白藜芦醇各剂量组及阳性对照组小鼠ALT及AST水平均低于模型组(P<0.01)。模型组小鼠肝脏炎症积分及损伤面积均高于正常对照组(P<0.01);白藜芦醇各剂量组及阳性对照组小鼠肝脏炎症积分及损伤面积均低于模型组(P<0.05或P<0.01)。模型组小鼠NLRP3、ASC、caspase-1、IL-1β及IL-18表达高于正常对照组(P<0.01);白藜芦醇各剂量组及阳性对照组小鼠NLRP3、ASC、caspase-1、IL-1β及IL-18表达均低于模型组(P<0.05或P<0.01)。病理组织切片显示,模型组小鼠肝细胞结构表现为胞浆疏松,小叶内坏死灶较多,坏死灶中可见中性粒细胞浸润;白藜芦醇各剂量组及阳性对照组小叶内坏死灶及中性粒细胞浸润等改变较模型组减少,肝细胞的受损面积较小。结论白藜芦醇可以显著减轻四氯化碳诱导的ALI,其机制可能与抑制NLRP3炎性体活化及其下游炎症级联反应有关。     

肠道疾病中胆汁酸及其受体对NLRP3炎症小体调控作用的研究进展

胆汁酸作为一种重要的内源性信号分子,参与机体代谢、免疫和炎症等多种生理病理过程,对维持肠道的正常生理功能具有重要作用。核苷酸结合寡聚结构域样受体蛋白3（NLRP3）炎症小体是一种模式识别受体,可通过识别病原体相关分子模式或危险相关分子模式,感知外源性微生物或来自损伤、死亡细胞的内源性危险信号,从而调节肠道免疫进程。研究表明,胆汁酸与NLRP3炎症小体之间存在多种调控模式,共同参与肠道稳态维持和疾病调节。基于国内外现有相关研究综述了肠道疾病中胆汁酸及其受体对NLRP3炎症小体调控作用的研究进展。     

Lung burdens and kinetics of multi-walled carbon nanotubes (Baytubes) are highly dependent on the disaggregation of aerosolized MWCNT

Abstract

Previous repeated inhalation exposure studies on rats with multi-walled carbon nanotubes (MWCNT, Baytubes®) suggested that their pulmonary toxicity was predominated by the morphology and density of the aggregated structure. Evidence of any disintegration of these structures in the lung did not exist. The objective of this study was to study as to which extent the formulation of pristine MWCNT as wet-dispersion changes the morphology of assemblage structures in the presence of disintegrated sub-structures. The focus was on the comparative inhalation dosimetry and kinetics of dry- and wet-dispersed Baytubes to better understand the cause of putative differences in pulmonary toxicity originating from pristine and rigorously formulated MWCNT. Rats were nose-only exposed to dry-dispersed and wet-dispersed Baytubes for 6-h at 25–30?mg/m³. Aerodynamic particle size measurements demonstrate substantial differences in the particle size of dry- (MMAD 2.6?µm) and wet-dispersed (MMAD 0.8?µm) MWCNT. Time-course changes of MWCNT retained in the lung were examined during a post-exposure period of 3 months. Lung burdens were analytically determined in digested lungs using the EC/OC total carbon method. Dosimetry was complemented by light and transmission electron microscopy (TEM) of MWCNT retained in alveolar macrophages (AM). As a result, the initially deposited pulmonary dose of MWCNT was three times higher following wet-dispersed MWCNT at essentially similar inhalation chamber concentrations. The elimination half-time of dry- and wet-dispersed MWCNT was 87 and 46?d, respectively. TEM provided evidence that wet-dispersed MWCNT were inhaled as disintegrated structures with distribution-patterns within the cytoplasm of AMs that differed appreciably from those of dry-dust exposed animals. In summary, this study shows that specialized technical processes to formulate MWCNT may have dramatic consequences on their pulmonary fate and associated toxicity. Such properties can only be revealed by the comparison of pulmonary toxicity with pulmonary (micro-)dosimetry and kinetics.     

PM2.5致大鼠肺损伤模型中肺巨噬细胞NLRP3 炎性小体活化研究

摘要： 目的 探讨肺巨噬细胞NLRP3炎性小体活化在大气细颗粒物 （PM2.5） 所致肺炎症损伤中的作用。方法 采用中流量采样器收集PM2.5颗粒物制成混悬液, 经气管滴注给予高、 中、 低剂量 （分别为15、 10、 5 mg/kg） 制成大鼠肺损伤模型, 3 d后麻醉动物进行肺泡灌洗, 收集支气管肺泡灌洗液 （BALF） 中的巨噬细胞, 中性红法测定其吞噬功能, 并采用免疫荧光双染色观察肺巨噬细胞内NLRP3的表达; 处死大鼠解剖取肺组织, HE染色观察肺损伤严重程度并评分, 免疫组化法检测肺组织NLRP3表达, ELISA法测定肺组织内IL-18、 IL-1β及Caspase-1的表达情况。结果 大鼠经气管滴注PM2.5染毒后, BALF内巨噬细胞吞噬功能下降。实验组大鼠肺损伤明显, 表现为间质性肺炎; 肺泡间隔明显增宽, 部分肺泡壁断裂, 尤以高剂量组表现明显; 各实验组大鼠的肺组织病理学评分均明显高于对照组 （均 P＜0.05）。低、 中、 高剂量组大鼠肺组织内NLRP3表达均高于对照组。肺组织内IL-18、 IL-1β及Caspase-1的表达不同程度上调。结论 大鼠气管滴注PM2.5引起的肺损伤和炎症反应与肺巨噬细胞内NLRP3炎症小体的活化有关。     

Ulinastatin ameliorates the malignant progression of prostate cancer cells by blocking the RhoA/ROCK/NLRP3 pathway

Prostate cancer is a male malignant tumor disease with high incidence and mortality. This study was designed to explore the effects of ulinastatin (UTI) on the malignant progression of prostate cancer and its relevant mechanism of action. Human prostate cancer cell line PC-3 was applied to investigate the anticancer activity of UTI. PC-3 cells were treated with increasing concentrations (400, 800, and 1600 U/ml) of UTI. Cell proliferation, migration, invasion, and apoptosis were determined by cell counting kit-8 (CCK-8), colony formation, wound-healing, Transwell assay, and flow cytometry analysis, respectively. The expression level of corresponding proteins was detected by western blot. In addition, PC-3 cells were pretreated with RhoA agonist CN03 (1 μg/ml) or NLRP3 agonist nigericin (10 μM) before UTI treatment, and the cellular behaviors above were detected again. It was demonstrated that UTI significantly suppressed cell proliferation, migration, and invasion but promoted apoptosis in PC-3 cells in a concentration-dependent manner. Meanwhile, UTI could block RhoA/ROCK/NLRP3 inflammasome pathway in PC-3 cells, and the activation of RhoA or NLRP3 inflammasome partly weakened the impacts of UTI on cell proliferation, migration, and apoptosis in PC-3 cells, respectively. In summary, our study demonstrated the antitumor activity of UTI against prostate cancer by regulating RhoA/NLRP3 inflammasome pathway, providing a promising candidate drug for the therapeutic treatment of prostate cancer.     

Ghrelin attenuates secondary brain injury following intracerebral hemorrhage by inhibiting NLRP3 inflammasome activation and promoting Nrf2/ARE signaling pathway in mice

Ghrelin, a brain-gut peptide, has been proven to exert neuroprotection in different kinds of neurological diseases; however, its role and the potential molecular mechanisms in secondary brain injury (SBI) after intracerebral hemorrhage (ICH) are still unknown. In this study, we investigate whether treatment with ghrelin may attenuate SBI in a murine ICH model, and if so, whether the neuroprotective effects are due to the inhibition of nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation and promotion of nuclear factor-E2-related factor 2 (Nrf2)/antioxidative response element (ARE) signaling pathway. Stereotactically intrastriatal infusion of autologous blood was performed to mimic ICH. Ghrelin was given intraperitoneally immediately following ICH and again 1 h later. Results showed that ghrelin attenuated neurobehavioral deficits, brain edema, hematoma volume, and perihematomal cell death post-ICH. Ghrelin inhibited the NLRP3 inflammasome activation and subsequently suppressed the neuroinflammatory response as evidenced by reduced microglia activation, neutrophil infiltration, and pro-inflammatory mediators release after ICH. Additionally, ghrelin alleviated ICH-induced oxidative stress according to the chemiluminescence of luminol and lucigenin, malondialdehyde (MDA) content, and total superoxide dismutase (SOD) activity assays. These changes were accompanied by upregulation of Nrf2 expression, Nrf2 nuclear accumulation, and enhanced Nrf2 DNA binding activity, as well as by increased expressions of Nrf2 downstream target antioxidative genes, including NAD(P)H quinine oxidoreductase-1 (NQO1), glutathione cysteine ligase regulatory subunit (GCLC), and glutathione cysteine ligase modulatory subunit (GCLM). Together, our data suggested that ghrelin protected against ICH-induced SBI by inhibiting NLRP3 inflammasome activation and promoting Nrf2/ARE signaling pathway.     

Evaluation of oxidative stress and anti-oxidant status in rat serum following exposure of carbon nanotubes

The aim of the present study was to evaluate the oxidative stress and anti-oxidant status in rat serum following intra-tracheal instillation of multi wall carbon nanotubes (MWCNT). The lungs of rats were intra-tracheally instilled with (single dose of) Phosphate-buffered saline (PBS)+1% of Tween 80 (Solvent Control) or MWCNT or carbonyl Iron (negative control) or quartz particles (positive control) at a dose of 0.2, 1 and 5 mg/kg body weight. Following exposure, the blood samples were collected at 1, 7, 30 and 90 days of post instillation of nanoparticles and different parameters were estimated to assess the oxidative stress induced by the instillation of MWCNT. Exposure of MWCNT to rats produced a significant (p<0.05) dose dependent reduction of blood total anti-oxidant capacity, glutathione, superoxide dismutase, catalase activity and increased lipid peroxidation product, (Malondialdehyde) levels than PBS+1% Tween 80 control group. This reduction in the total anti-oxidant capacity in nanotubes exposed rats indicates the reduction in anti-oxidant deference mechanisms due to the instillation of MWCNT. These results indicate that, exposure of multi wall carbon nanotubes induces oxidative stress by reducing the total anti-oxidant capacity in rats. The findings suggest possible occupational health hazard in chronic exposures.