Tiron ameliorates acetic acid-induced colitis in rats: Role of TGF-ß/EGFR/PI3K/NF-κB signaling pathway.

BACKGROUND: Ulcerative colitis (UC), an ongoing inflammatory disorder of the colon, is marked by persistent mucosal surface irritation extending from the rectum to the near-proximal colon. Tiron is a synthetic analogue of vitamin E which is known to have antioxidant and anti-inflammatory effects in various animal models, so the goal of this study was to find out whether Tiron had any preventive impacts on UC inflicted by acetic acid (A.A) exposure in rats. METHOD: Tiron (235 and 470 mg/kg) was administered intra-peritoneally for 2 weeks, and A.A (2 ml, 3 % v/v) was injected intra-rectally to cause colitis. Colon tissues and blood samples were then collected for measurement of various inflammatory and oxidative stress biomarkers. RESULTS: Tiron administration significantly diminished lactate dehydrogenase (LDH), C-reactive protein (CRP), colon weight, and the weight/length ratio of the colon as compared to A.A-injected rats. Additionally, Tiron attenuated oxidative stress biomarkers. Tiron also enforced the levels of Glucagon-like peptide-1 (GLP-1) and trefoil factor-3 (TFF-3), while it greatly lowered the expression of nuclear factor kappa B (NF-κB), interleukin-6 (IL-6), interferon-γ (IFN-γ), and transforming growth factor-1(TGF-ß1), phosphorylated epidermal growth factor receptor (P-EGFR), phosphatidylinositol-3-kinase (PI3K) and protein kinase B (AKT) expression in colonic cellular structures. Furthermore, colonichistopathologic damages, revealed by hematoxylin and eosin (H&E) and Alcian Blue stain, were significantly decreased upon Tiron administration. CONCLUSION: Tiron prevented A.A-induced colitis in rats via modulating inflammatory pathway TGF-ß1/P-EGFR/PI3K/AKT/NF-κB, alongside managing the oxidant/antioxidant equilibrium, and boosting the reliability of the intestinal barrier.

Inhibition of IL-6 signaling prevents serum-induced umbilical cord artery dysfunction from patients with severe COVID-19.

Coronavirus disease 2019 (COVID-19) infection has a negative impact on the cytokine profile of pregnant women. Increased levels of proinflammatory cytokines seem to be correlated with the severity of the disease, in addition to predisposing to miscarriage or premature birth. Proinflammatory cytokines increase the generation of reactive oxygen species (ROS). It is unclear how interleukin-6 (IL-6) found in the circulation of patients with severe COVID-19 might affect gestational health, particularly concerning umbilical cord function. This study tested the hypothesis that IL-6 present in the circulation of women with severe COVID-19 causes umbilical cord artery dysfunction by increasing ROS generation and activating redox-sensitive proteins. Umbilical cord arteries were incubated with serum from healthy women and women with severe COVID-19. Vascular function was assessed using concentration-effect curves to serotonin in the presence or absence of pharmacological agents, such as tocilizumab (antibody against the IL-6 receptor), tiron (ROS scavenger), ML171 (Nox1 inhibitor), and Y27632 (Rho kinase inhibitor). ROS generation was assessed by the dihydroethidine probe and Rho kinase activity by an enzymatic assay. Umbilical arteries exposed to serum from women with severe COVID-19 were hyperreactive to serotonin. This effect was abolished in the presence of tocilizumab, tiron, ML171, and Y27632. In addition, serum from women with severe COVID-19 increased Nox1-dependent ROS generation and Rho kinase activity. Increased Rho kinase activity was abolished by tocilizumab and tiron. Serum cytokines in women with severe COVID-19 promote umbilical artery dysfunction. IL-6 is key to Nox-linked vascular oxidative stress and activation of the Rho kinase pathway.

NLRP3 activation contributes to endothelin-1-induced erectile dysfunction.

In the present study, we hypothesized that endothelin (ET) receptors (ETA and ETB ) stimulation, through increased calcium and ROS formation, leads to Nucleotide Oligomerization Domain-Like Receptor Family, Pyrin Domain Containing 3 (NLRP3) activation. Intracavernosal pressure (ICP/MAP) was measured in C57BL/6 (WT) mice. Functional and immunoblotting assays were performed in corpora cavernosa (CC) strips from WT, NLRP3-/- and caspase-/- mice in the presence of ET-1 (100 nM) and vehicle, MCC950, tiron, BAPTA AM, BQ123, or BQ788. ET-1 reduced the ICP/MAP in WT mice, and MCC950 prevented the ET-1 effect. ET-1 decreased CC ACh-, sodium nitroprusside (SNP)-induced relaxation, and increased caspase-1 expression. BQ123 an ETA receptor antagonist reversed the effect. The ETB receptor antagonist BQ788 also reversed ET-1 inhibition of ACh and SNP relaxation. Additionally, tiron, BAPTA AM, and NLRP3 genetic deletion prevented the ET-1-induced loss of ACh and SNP relaxation. Moreover, BQ123 diminished CC caspase-1 expression, while BQ788 increased caspase-1 and IL-1ß levels in a concentration-dependent manner (100 nM-10 µM). Furthermore, tiron and BAPTA AM prevented ET-1-induced increase in caspase-1. In addition, BAPTA AM blocked ET-1-induced ROS generation. In conclusion, ET-1-induced erectile dysfunction depends on ETA - and ETB -mediated activation of NLRP3 in mouse CC via Ca2+ -dependent ROS generation.

Tiron Has Negative Effects on Osteogenic Differentiation via Mitochondrial Dysfunction in Human Periosteum-Derived Cells.

Tiron is a potent antioxidant that counters the pathological effects of reactive oxygen species (ROS) production due to oxidative stress in various cell types. We examined the effects of tiron on mitochondrial function and osteoblastic differentiation in human periosteum-derived cells (hPDCs). Tiron increased mitochondrial activity and decreased senescence-associated ß-galactosidase activity in hPDCs; however, it had a detrimental effect on osteoblastic differentiation by reducing alkaline phosphatase (ALP) activity and alizarin red-positive mineralization, regardless of H2O2 treatment. Osteoblast-differentiating hPDCs displayed increased ROS production compared with non-differentiating hPDCs, and treatment with tiron reduced ROS production in the differentiating cells. Antioxidants decreased the rates of oxygen consumption and ATP production, which are increased in hPDCs during osteoblastic differentiation. In addition, treatment with tiron reduced the levels of most mitochondrial proteins, which are increased in hPDCs during culture in osteogenic induction medium. These results suggest that tiron exerts negative effects on the osteoblastic differentiation of hPDCs by causing mitochondrial dysfunction.

Tirons of the world: a review of tironid amphipods, description of new genera and species, and establishment of a new subfamily Tironinae Stebbing, 1906 stat. nov. (Crustacea, Synopiidae).

The classification of a group of Synopiidae is reviewed based primarily on new material from Australasia and the northern Pacific. A synopiid subfamily, Tironinae Stebbing, 1906 stat. nov. is diagnosed for the following six genera (3 new) consisting of 38 species (18 new): Tiron Lilljeborg, 1865, with 6 species, T. spiniferus Stimpson (type species), T. antarcticus K.H. Barnard, 1932, T. biocellatus J.L. Barnard, 1962, T. canadense sp. nov., T. lilljeborgi sp. nov., and T. sagamiense sp. nov.; Tironella gen. nov. with 3 species, T. altifrons (Reid, 1951, ex Tiron) comb. nov., T. bathyalis sp. nov. (type species), and T. pervicax (J.L. Barnard, 1967, ex Pseudotiron) comb. nov.; Glandulotiron gen. nov. with 15 species, G. pilocaputis sp. nov. (type species), G. salsevisio sp. nov., G. hexamatius sp. nov., G. spinipes sp. nov., G. concavus sp. nov., G. septimus sp. nov., G. meruspinosus sp. nov., G. bassianus sp. nov., G. curvispinus sp. nov., G. aotearoensis sp. nov., G. postremus sp. nov., G. griffithsi sp. nov., G. intermedius (Reid, 1951; ex Tiron) comb. nov., G. quadrioculatus (Dang Le, 2012; ex Tiron) comb. nov., and G. australis (Stebbing, 1908; ex Tiron) comb. nov.; Pseudotiron Chevreux, 1895 with 4 species, P. bouvieri Chevreux, 1895, P. coas J.L. Barnard, 1967, P. golens J.L. Barnard, 1962, P. miratus sp. nov.; Metatiron Rabindranath, 1972, with 4 species, M. brevidactylus (Pillai, 1954, type species), M. bonaerensis Alonso de Pina, 1998, M. triocellatus (Goeke, 1982) and M. tropakis (J.L. Barnard, 1972); and Minitiron gen. nov. with 6 species, M. orpheus sp. nov. (type species), M. bellairsi (Just, 1981; ex. Metatiron) comb. nov., M. caecus (Ledoyer, 1979; ex. Metatiron) comb. nov., M. galeatus (Hirayama, 1988; ex Tiron) comb. nov., M. ovatibasis (Hirayama, 1988; ex Tiron) comb. nov., M. thompsoni (Walker, 1904; ex Tiron) comb. nov. Three species currently in Pseudotiron (P. longicaudatus Pirlot, 1934; P. sublongicaudatus Dang Le, 2012; P. livingstonae Lrz Coleman, 2013) are removed to Synopiidae incertae sedis. Metatiron brevidactylus (Pillay, 1957) by Ledoyer (1979) is removed to Minitiron incerta sedis. Species in the new genus Glandulotiron and a new species of Pseudotiron possess rows of elongate glands in uropods and the telson previously unknown in amphipods. A new key is presented for synopiid genera together with a key to world tironin genera and separate keys for the individual tironin genera. Global distribution and more detailed Australian distribution of the tironins are shown.

Adding of neurotensin to non-small cell lung cancer cells increases tyrosine phosphorylation of HER3.

Neurotensin (NTS) receptor 1 regulates the growth non-small cell lung cancer (NSCLC) cells. NTS binds with high affinity to NTSR1, leading to increased tyrosine phosphorylation of the EGFR and HER2. Using Calu3, NCI-H358, or NCI-H441 cells, the effects of NTS on HER3 transactivation were investigated. HER3 tyrosine phosphorylation was increased by NTS or neuregulin (NRG1) addition to NSCLC cells. NCI-H358, NCI-H441, and Calu-3 cells have HER3, NTSR1 and neuregulin (NRG)1 protein. NTSR1 regulation of HER3 transactivation was impaired by SR48692 (NTSR1 antagonist) or monoclonal antibody (mAb)3481 (HER3 blocker). Immunoprecipitation experiments indicated that NTS addition to NCI-H441cells resulted in the formation of EGFR/HER3 and HER2/HER3 heterodimers. The ability of NTS to increase HER3 tyrosine phosphorylation was impaired by GM6001 (MMP inhibitor), PP2 (Src inhibitor), Tiron (superoxide scavenger), or N-acetylcysteine (antioxidant). Adding NTS to NSCLC cells increased phosphorylation of ERK, HER3, and AKT. NTS or NRG1 increased colony formation of NSCLC cells which was strongly inhibited by SR48692 and mAb3481. The results indicate that NTSR1 regulates HER3 transactivation in NSCLC cells leading to increased proliferation.

Tiron alleviates MPTP-induced Parkinsonism in mice via activation of Keap-1/Nrf2 pathway.

Parkinsonism is a neurodegenerative disease that is common all over the world. This study aimed at exploring the neuroprotective effect of tiron against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinsonism. MPTP (30 mg/kg, intraperitoneally [ip]) was injected in mice daily for 5 consecutive days. Mice were treated with tiron (140 and 280 mg/kg, ip) or levodopa (8.4 mg/kg, orally) for 10 consecutive days starting 5 days before MPTP injection. At the end of the experiment, behavioral tests were conducted to assess the neuroprotective effect of tiron. Moreover, oxidative stress was assessed via measuring antioxidant enzyme, such as catalase, and lipid peroxidation was evaluated as malondialdehyde. Neuronal damage was also detected by histopathological examination and via estimating hippocampal levels of dopamine, γ-aminobutyric acid, and nuclear factor erythroid-derived 2-like 2. In addition, the expression of Kelch-like ECH-associated protein 1 and heme oxygenase-1 was assessed by immunohistochemistry. Compared with the blank control group and the positive control group, the inhibitory effect of tiron on MPTP-induced neurodegenerative injury was statistically significant.

Tiron protects against nicotine-induced lung and liver injury through antioxidant and anti-inflammatory actions in rats in vivo.

AIMS: Tobacco smoking is a major health problem associated with lung and liver damage. Lung and liver damage secondary to tobacco smoking is mediated through nicotine-induced oxidative stress. Therefore, we hypothesized that antioxidant treatment with tiron may improve nicotine-induced lung and liver damage. MATERIALS AND METHODS: Rats were divided into six groups, a control, nicotine (10 mg/kg/day, i.p.; for 8 weeks) and tiron (100 or 200 mg/kg/day, i.p.; for 8 weeks) with or without nicotine administration. KEY FINDINGS: Tiron improved survival rate and attenuated lung and liver damage as reflected by decreased total and differential cell counts, lactate dehydrogenase (LDH) activity in bronchoalveolar lavage fluid (BALF) and decreased alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in serum; also histopathological examination confirmed the protective effect of tiron in lung and liver tissues of nicotine treated rats. Tiron attenuated dyslipidemia, which is associated with nicotine. These ameliorative effects of tiron may be mainly due to its antioxidant effect as proved by a significant decrease in malondialdehyde (MDA) content, reactive oxygen species (ROS) and total nitrite/nitrate (NOx) levels, and increase in reduced glutathione (GSH) level, catalase (CAT) and superoxide dismutase (SOD) activities. This is likely related to suppression of protein levels of NADPH oxidase enzyme (NOX1), inducible nitric oxide synthase (iNOS), nuclear factor kappa B (NF-κB) and tumor necrosis factor alpha (TNF-α); and up-regulation of protein levels of nuclear factor erythroid-2 (Nrf2). SIGNIFICANCE: This makes tiron (synthetic analogue of vitamin E) good candidate for future use to minimize nicotine's hazards among smokers.

LAP-like non-canonical autophagy and evolution of endocytic vacuoles in pancreatic acinar cells.

Activation of trypsinogen (formation of trypsin) inside the pancreas is an early pathological event in the development of acute pancreatitis. In our previous studies we identified the activation of trypsinogen within endocytic vacuoles (EVs), cellular organelles that appear in pancreatic acinar cells treated with the inducers of acute pancreatitis. EVs are formed as a result of aberrant compound exocytosis and subsequent internalization of post-exocytic structures. These organelles can be up to 12 µm in diameter and can be actinated (i.e. coated with F-actin). Notably, EVs can undergo intracellular rupture and fusion with the plasma membrane, providing trypsin with access to cytoplasmic and extracellular targets. Unraveling the mechanisms involved in cellular processing of EVs is an interesting cell biological challenge with potential benefits for understanding acute pancreatitis. In this study we have investigated autophagy of EVs and discovered that it involves a non-canonical LC3-conjugation mechanism, reminiscent in its properties to LC3-associated phagocytosis (LAP); in both processes LC3 was recruited to single, outer organellar membranes. Trypsinogen activation peptide was observed in approximately 55% of LC3-coated EVs indicating the relevance of the described process to the early cellular events of acute pancreatitis. We also investigated relationships between actination and non-canonical autophagy of EVs and concluded that these processes represent sequential steps in the evolution of EVs. Our study expands the known roles of LAP and indicates that, in addition to its well-established functions in phagocytosis and macropinocytosis, LAP is also involved in the processing of post-exocytic organelles in exocrine secretory cells. ABBREVIATIONS: AP: acute pancreatitis; CCK: cholecystokinin; CLEM: correlative light and electron microscopy; DPI: diphenyleneiodonium; EV: endocytic vacuole; LAP: LC3-associate phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; PACs: pancreatic acinar cells; PFA: paraformaldehyde; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; Res: resveratrol; TAP: trypsinogen activation peptide; TEM: transmission electron microscopy; TLC-S: taurolithocholic acid 3-sulfate; TRD: Dextran Texas Red 3000 MW Neutral; ZGs: zymogen granules.

Modulating effect of tiron on the capability of mitochondrial oxidative phosphorylation in the brain of rats exposed to radiation or manganese toxicity.

The brain is an important organ rich in mitochondria and more susceptible to oxidative stress. Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) is a potent antioxidant. This study aims to evaluate the effect of tiron on the impairment of brain mitochondria induced by exposure to radiation or manganese (Mn) toxicity. We assessed the capability of oxidative phosphorylation (OXPHOS) through determination of mitochondrial redox state, the activity of electron transport chain (ETC), and Krebs cycle as well as the level of adenosine triphosphate (ATP) production. Rats were exposed to 7 Gy of γ-rays or injected i.p. with manganese chloride (100 mg/kg), then treated with tiron (471 mg/kg) for 7 days. The results showed that tiron treatment revealed positive modulation on the mitochondrial redox state manifested by a marked decrease of hydrogen peroxide (H2O2), malondialdehyde (MDA), and total nitrate/nitrite (NOx) associated with a significant increase in total antioxidant capacity (TAC), glutathione (GSH) content, manganese superoxide dismutase (MnSOD), and glutathione peroxidase (GPx) activities. Moreover, tiron can increase the activity of ETC through preventing the depletion in the activity of mitochondrial complexes (I, II, III, and IV), an elevation of coenzyme Q10 (CoQ10) and cytochrome c (Cyt-c) levels. Additionally, tiron showed a noticeable increase in mitochondrial aconitase (mt-aconitase) activity as the major component of Krebs cycle to maintain a high level of ATP production. Tiron also can restore mitochondrial metal homeostasis through positive changes in the levels of calcium (Ca), iron (Fe), Mn, and copper (Cu). It can be concluded that tiron may be used as a good mitigating agent to attenuate the harmful effects on the brain through the inhibition of mitochondrial injury post-exposure to radiation or Mn toxicity.

Superoxide anions modulate the performance of apelin in the paraventricular nucleus on sympathetic activity and blood pressure in spontaneously hypertensive rats.

The present study was designed to determine how apelin in paraventricular nucleus (PVN) modulates the renal sympathetic nerve activity (RSNA), arterial blood pressure (ABP), mean arterial pressure (MAP), and heart rate (HR), and whether superoxide anions regulate the performance of PVN apelin in spontaneously hypertensive rats (SHRs). Acute experiment was carried out with 13-week-old male Wistar-Kyoto rats (WKY) and SHRs under anaesthesia. RSNA, ABP, MAP and HR after PVN microinjection were measured. Apelin microinjection into PVN increased RSNA, ABP, MAP and HR in WKY rats and SHRs, more obviously in SHRs. APJ antagonist F13A decreased the RSNA, ABP, MAP and HR in SHRs, and inhibited the effects of apelin. Apelin and APJ mRNA levels were higher in the PVN in SHRs. PVN microinjection of superoxide anion scavengers tempol and tiron, or NAD(P)H oxidase inhibitor apocynin, decreased the RSNA, ABP, MAP and HR in SHRs, and inhibited the effects of apelin, but the superoxide dismutase (SOD) inhibitor diethyldithiocarbamic acid (DETC) potentiated the effects of apelin. NAD(P)H oxidase activity and superoxide anion levels in PVN were increased by apelin, but decreased by APJ antagonist F13A. The apelin-induced increases in NAD(P)H oxidase activity and superoxide anion level were abolished by pre-treatment with F13A. These results indicate that apelin in PVN increases the sympathetic outflow and blood pressure via activating APJ receptor. The enhanced activity of endogenous apelin and APJ receptor in PVN contributes to sympathetic activation in hypertension, and the superoxide anion is involved in these apelin-mediated processes in PVN.

Molecular mechanisms regarding potassium bromate­induced cardiac hypertrophy without apoptosis in H9c2 cells.

Cardiac hypertrophy is commonly involved in cardiac injury. Oxidative stress can induce cardiac hypertrophy with apoptosis. Potassium bromate (KBrO3) has been widely used as a food additive due to its oxidizing properties. In the present study, the rat­derived heart cell line H9c2 was used to investigate the effect of KBrO3 on cell size. KBrO3 increased cell size at concentrations <250 µM, in a dose­dependent manner. Additionally, KBrO3 also promoted the gene expression of two biomarkers of cardiac hypertrophy, brain/B­type natriuretic peptides (BNP) and ß­Myosin Heavy Chain (ß­MHC). However, apoptosis remained unobserved in these cells. Moreover, mediation of free radicals was investigated using a fluorescence assay, and it was observed that superoxide and reactive oxygen species (ROS) levels increased with KBrO3. Effects of KBrO3 were significantly reduced by tiron at concentrations sufficient to produce antioxidant­like action. Additionally, signals involved in cardiac hypertrophy such as calcineurin and nuclear factor of activated T­cells (NFAT) were also determined using western blot analysis. KBrO3 increased the protein levels of both these molecules which were decreased by tiron in a dose­dependent manner. Additionally, cyclosporine A attenuated the cardiac hypertrophy induced by KBrO3 in H9c2 cells at concentrations effective to inhibit calcineurin, in addition to reducing mRNA levels of BNP or ß­MHC. Finally, apoptosis was also identified in H9c2 cells incubated with KBrO3 at concentrations >300 µM. Collectively, these results provided a novel perspective that KBrO3 induces cardiac hypertrophy without apoptosis at a low dose through the generation of ROS, activating the calcineurin/NFAT signaling pathway in H9c2 cells. Therefore, at a dose <250 µM, KBrO3 can be applied as an inducer of cardiac hypertrophy without apoptosis in H9c2 cells. KBrO3 can also be developed as a tool to induce cardiac hypertrophy in animals.

Innovative perception on using Tiron to modulate the hepatotoxicity induced by titanium dioxide nanoparticles in male rats.

The extensive application of titanium dioxide nanoparticles (TiO2 NPs) in the food industry arouses a debate regarding the probable risk associated with their use. Several recent studies reported that most nanoparticles (NPs) have adverse actions on the liver. The objective of this study is to examine whether Tiron plays a modulatory role against apoptotic damage induced by TiO2 NPs in rat livers. Forty rats were randomly divided into 4 groups; a control group received phosphate-buffered saline, an intoxicated group received 100 mg/kg/day of TiO2 NPs for 60 days, a treated group received 470 mg/kg/day of Tiron for the last 14 days after TiO2 NPs administration, and a Tiron group received Tiron only as previously mentioned. Oral administration of TiO2 NPs significantly increased serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). In the liver, TiO2 NPs increased oxidative stress through increasing lipid peroxidation and decreasing GSH concentration and the levels of the SOD and GPx enzymes. TiO2 NPs significantly upregulated the proapoptotic Bax gene and downregulated the antiapoptotic Bcl-2 gene. Histopathological examination of hepatic tissue reinforced the previous biochemical results. Apoptotic lesions were also obvious in this group. Treatment with Tiron as an antioxidant significantly decreased serum biochemistry, ameliorated oxidative stress in hepatic tissue, upregulated Bcl-2, decreased Bax expression and attenuated the histopathology of hepatic injury. These findings indicate that Tiron effectively diminishes the hazardous effects of TiO2 NPs on rat liver.

Tiron ameliorates oxidative stress and inflammation in titanium dioxide nanoparticles induced nephrotoxicity of male rats.

Although the widespread use of titanium dioxide nanoparticles (TiO2 NPs), few studies were conducted on its hazard influence on human health. Tiron a synthetic vitamin E analog was proven to be a mitochondrial targeting antioxidant. The current investigation was performed to assess the efficacy of tiron against TiO2 NPs induced nephrotoxicity. Eighty adult male rats divided into four different groups were used: group I was the control, group II received TiO2 NPs (100mg\Kg BW), group III received TiO2 NPs plus tiron (470mg\kg BW), and group IV received tiron alone. Urea, creatinine and total protein concentrations were measured in serum to assess the renal function. Antioxidant status was estimated by determining the activities of glutathione peroxidase, superoxide dismutase, malondialdehyde (MDA) level and glutathione concentration in renal tissue. As well as Renal fibrosis was evaluated though measuring of transforming growth factor-ß1 (TGFß1) and matrix metalloproteinase 9 (MMP9) expression levels and histopathological examination. TiO2 NPs treated rats showed marked elevation of renal indices, depletion of renal antioxidant enzymes with marked increase in MDA concentration as well as significant up-regulation in fibrotic biomarkers TGFß1 and MMP9. Oral administration of tiron to TiO2 NPs treated rats significantly attenuate the renal dysfunction through decreasing of renal indices, increasing of antioxidant enzymes activities, down-regulate the expression of fibrotic genes and improving the histopathological picture for renal tissue. In conclusion, tiron was proved to attenuate the nephrotoxicity induced by TiO2 NPs through its radical scavenging and metal chelating potency.

The nitric oxide donor RuBPY does not induce in vitro cross-tolerance with acetylcholine.

PURPOSE: We have demonstrated that RuBPY induces hypotensive effect in hypertensive rats, promotes vasodilation at low concentrations, and presents low cytotoxicity. This study aimed to verify whether the NO donor RuBPY synthesized in our laboratory induces in vitro tolerance and cross-tolerance to acetylcholine (ACh) and sodium nitroprusside (SNP) in rat cava vein. METHODS: We compared the maximum relaxing effect (ME) and potency (pD2) of RuBPY and nitroglycerin (GTN) in cava vein rings. Exposure to RuBPY or GTN induced in vitro tolerance. Western Blotting helped to evaluate phosphorylation of endothelial nitric oxide synthase (NOS3/eNOS) at the Ser1177 activation site and at the Thr495 inactivation site and to determine the ratio between active eNOS dimers and inactive eNOS monomers. The NO and ROS ratio was assessed by flow citometry. RESULTS: RuBPY did not induce cross-tolerance with ACh, and this NO donor took longer to induce tolerance than GTN. Only GTN elicited phosphorylation of eNOS at Ser1177 and Thr495. In contrast to results obtained with pre-exposure to GTN, pre-exposure to RuBPY did not reduce the formation of NO. The O2- ratio increased in cells incubated with GTN. CONCLUSIONS: A major contribution of this work has been to evaluate the phenomenon of tolerance induced by GTN and by the new ruthenium complex RuBPY in a venous bed. RuBPY is more advantageous than GTN: RuBPY takes longer to induce tolerance, does not induce endothelial dysfunction or cross-tolerance to ACh, and generates lower amount of ROS.

Tiron ameliorates high glucose-induced cardiac myocyte apoptosis by PKCδ-dependent inhibition of osteopontin.

Tiron functions as an effective antioxidant alleviating the intracellular reactive oxygen species (ROS) or the acute toxic metal overload. Previous studies have shown that cardiac myocyte apoptosis can be effectively inhibited by tiron administration in streptozotocin (STZ)-induced diabetic rats, primary neonatal rat cardiomyocytes (NRVMs), and H9c2 embryonic rat cardiomyocytes. However, the underlying signalling mechanism is ill-defined. In the present study, we found that tiron supplementation significantly inhibited apoptosis of high glucose (HG)-treated NRVMs and the left ventricular cardiomyocytes from STZ-diabetic rat, accompanied with a reduction of osteopontin (OPN) levels as well as an inhibition of PKCδ phosphorylation. OPN knockdown protected NRVMs against HG-induced cell apoptosis. In addition, genetic inhibition of PKCδ mitigated HG-stimulated enhancement of intracellular OPN levels in NRVMs. These findings indicate that ROS-mediated activation of PKCδ upregulated OPN expression, leading to cardiac myocyte apoptosis. Interfering with ROS/PKCδ pathway by antioxidants such as tiron provides an optional therapeutic strategy for treatment and prevention of apoptosis-related cardiovascular diseases including diabetic cardiomyopathy.

Reproductive toxicity provoked by titanium dioxide nanoparticles and the ameliorative role of Tiron in adult male rats.

Titanium dioxide nanoparticles (TDN) are widely used in paints, plastics, ceramics, cosmetics, printing ink, rubber and paper. Tiron is a water soluble metal chelator and antioxidant. This study was designed to investigate the reproductive toxicity of TDN in male albino rats and the ameliorative role of Tiron to minimize such toxic effects. Eighty adult male albino rats were assigned into 4 equal groups, group 1: control; group 2: received TDN at 100 mg/kg/day orally for 8 weeks; group 3: received Tiron at 470 mg/kg/day intraperitoneally for 2 weeks (the last 2 weeks of the experimental period); group 4: received both TDN and Tiron by the same previously mentioned dose, route and duration. The results revealed that TDN provoked reproductive toxicity which was proved by the deteriorated spermogram picture, high incidence of micronucleated RBCs, elevated oxidative stress parameters and up regulation of Testin gene. Whereas, Tiron co-treatment ameliorated most of these toxic alterations. Our findings highlighted the protective role of tiron against TDN intoxication.

Biphasic augmentation of alpha-adrenergic contraction by plumbagin in rat systemic arteries

Plumbagin, a hydroxy 1,4-naphthoquinone compound from plant metabolites, exhibits anticancer, antibacterial, and antifungal activities via modulating various signaling molecules. However, its effects on vascular functions are rarely studied except in pulmonary and coronary arteries where NADPH oxidase (NOX) inhibition was suggested as a mechanism. Here we investigate the effects of plumbagin on the contractility of skeletal artery (deep femoral artery, DFA), mesenteric artery (MA) and renal artery (RA) in rats. Although plumbagin alone had no effect on the isometric tone of DFA, 1 µM phenylephrine (PhE)-induced partial contraction was largely augmented by plumbagin (ΔT(Plum), 125% of 80 mM KCl-induced contraction at 1 µM). With relatively higher concentrations (>5 µM), plumbagin induced a transient contraction followed by tonic relaxation of DFA. Similar biphasic augmentation of the PhE-induced contraction was observed in MA and RA. VAS2870 and GKT137831, specific NOX4 inhibitors, neither mimicked nor inhibited ΔT(Plum) in DFA. Also, pretreatment with tiron or catalase did not affect ΔT(Plum) of DFA. Under the inhibition of PhE-contraction with L-type Ca²⁺ channel blocker (nifedipine, 1 µM), plumbagin still induced tonic contraction, suggesting Ca²⁺-sensitization mechanism of smooth muscle. Although ΔT(Plum) was consistently observed under pretreatment with Rho A-kinase inhibitor (Y27632, 1 µM), a PKC inhibitor (GF 109203X, 10 µM) largely suppressed ΔT(Plum). Taken together, it is suggested that plumbagin facilitates the PKC activation in the presence of vasoactive agonists in skeletal arteries. The biphasic contractile effects on the systemic arteries should be considered in the pharmacological studies of plumbagin and 1,4-naphthoquinones.

Fusobacterium nucleatum-Induced Impairment of Autophagic Flux Enhances the Expression of Proinflammatory Cytokines via ROS in Caco-2 Cells.

Fusobacterium nucleatum (F. nucleatum) plays a critical role in gastrointestinal inflammation. However, the exact mechanism by which F. nucleatum contributes to inflammation is unclear. In the present study, it was revealed that F. nucleatum could induce the production of proinflammatory cytokines (IL-8, IL-1ß and TNF-α) and reactive oxygen species (ROS) in Caco-2 colorectal) adenocarcinoma cells. Furthermore, ROS scavengers (NAC or Tiron) could decrease the production of proinflammatory cytokines during F. nucleatum infection. In addition, we observed that autophagy is impaired in Caco-2 cells after F. nucleatum infection. The production of proinflammatory cytokines and ROS induced by F. nucleatum was enhanced with either autophagy pharmacologic inhibitors (3-methyladenine, bafilomycin A1) or RNA interference in essential autophagy genes (ATG5 or ATG12) in Caco-2 cells. Taken together, these results indicate that F. nucleatum-induced impairment of autophagic flux enhances the expression of proinflammatory cytokines via ROS in Caco-2 Cells.

Electrically induced fluorescence Fe3+ sensing behavior of nanostructured Tiron doped polypyrrole.

Nanostructured polypyrrole (PPy) film doped with Tiron was electrodeposited from aqueous solution on the surface of transparent electrode and used for sensitive, selective and rapid electrically controlled fluorescence detection of Fe3+ in aqueous media. The fluorescence intensity of PPy-Tiron film decreases linearly in the presence of Fe3+ by applying negative potential over a concentration range from 5.0 × 10-8 to 1.0 × 10-6 mol L-1, with a relatively fast response time of less than 30 s at pH 7.4. The detection is not affected by the coexistence of other competitive metal ions such as Al3+, Ce3+, Tl3+, La3+, Bi3+, Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+, Na+, K+, Mg2+, Ca2+, Sr2+ and Ba2+. The proposed electro-fluorescence sensor has a potential application to the determination of Fe3+ in environmental and biological systems. The fluorescent thin film sensor was also used as a novel probe for Fe3+/Fe2+ speciation in aqueous solution.