Oxidative stress enhances the immune response to oxidatively modified catalase enzyme in patients with Graves' disease.

BACKGROUND: Oxidative stress is associated with several autoimmune disorders and oxidative modification of proteins that may result in autoimmune response. This study aims to evaluate the catalase (CAT) activity and the autoimmune response against the native CAT and the oxidatively modified enzyme in patients with Graves' disease (GD) and healthy controls in a comparative way. METHODS: The CAT activity was evaluated via spectrophotometric method. Using enzyme-linked immunosorbent assay, the reactivities of autoantibody toward native, malondialdehyde (MDA) and hydrogen peroxide (H2 O2 ) modified CAT were evaluated in plasmas of patients and controls. RESULTS: Reduced CAT activity was found in patients compared with controls (P < .05). It was proved that levels of IgG antibodies against MDA-modified CAT were higher than against unmodified ones (P < .001). No changes were found for the reactivities to H2 O2 -modified CAT. Positive correlation was found between the reactivity to MDA-modified CAT and the triiodothyronine level (P < .001, r = .6). CONCLUSION: Our findings incriminate the MDA in the autoantibodies reactivity to oxidatively modified CAT leading to a disturbed oxidative profile and/or the progression of GD pathology.

Relationship of oxidative stress in the resistance to imatinib in Tunisian patients with chronic myeloid leukemia: A retrospective study.

BACKGROUND: This work aimed to evaluate oxidative stress in chronic myeloid leukemia (CML) patients treated with tunisian (IM) vs controls and in CML patients with resistance to IM vs patients without resistance to IM. METHODS: The study included 40 CML patients and 34 controls. Of 40 patients with CML, 26 patients were developed in resistance to IM. The oxidant/antioxidant markers were evaluated by spectrophotometric methods for all used samples. RESULTS: For CML patients, increased malondialdehyde (MDA) and advanced oxidation protein products (AOPP) levels were found compared to controls (P < .001; P = .01). Higher catalase (CAT) activity (P = .048) and lower superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, reduced Glutathione (GSH) and vitamin C levels were found in CML patients (P < .001). The comparison between the resistant vs no-resistant CML patients revealed higher MDA level (P = .02) and CAT and SOD activities in IM-resistant patients (P = .04, P = .03). GPx activity was reduced (P = .04). Furthermore, increased mean ratio of MDA/GSH, MDA/GPx, and SOD/(GPx + CAT) was found in IM-resistant patients as compared with no-resistant (P = .01, P = .01, P = .035). The mean ratio of GPx/GSH in the IM-resistant CML patients was lower than in IM no-resistant one (P = .039). For IM-resistant patients, we found negative correlation between MDA level and the ratio SOD/(CAT + GPx) (r = -0.46, P = .002); and positive correlation between SOD and (CAT + GPx) activities (r = 0.38, P = .06) and between GSH level and GPx activity (r = 0.53, P = .01). CONCLUSIONS: Our results have shown a highly disturbed oxidative profile in IM-resistant CML patients as compared to no-resistant. The H2 O2 has a key role in the resistance to IM treatment.

Human sperm Toll-like receptor 4 (TLR4) mediates acrosome reaction, oxidative stress markers, and sperm parameters in response to bacterial lipopolysaccharide in infertile men.

PURPOSE: To study the role of Toll-like receptor 4 (TLR4) in human spermatozoa and to assess sperm parameters, oxidative stress markers, and acrosome reaction in response to the stimulation of TLR4 by its ligand, the lipopolysaccharide (LPS), as a major endotoxin of Gram-negative bacteria. METHODS: Our study was carried out in 73 sperm samples from patients undergoing semen analysis for couple infertility investigations. The studied patients were divided into three groups: normozoospermic fertile patients (n = 13), patients with abnormal and leukospermic semen (n = 13), and patients with abnormal and non-leukospermic semen (n = 47). TLR4 expression in human spermatozoa was initially analyzed by western blot. Sperm samples were incubated in the presence of LPS (200 ng/ml) for 18 h. Then, sperm motility and vitality were evaluated by microscopic observation and oxidative stress markers as malondialdehyde (MDA) and carbonyl groups (CG) were spectrophotometrically assessed in neat and selected sperm. A triple-stain technique was also performed to evaluate acrosome reaction in 15 sperm samples from infertile patients. RESULTS: TLR4 expression was confirmed in human spermatozoa with a molecular weight of 69 kDa. In the normozoospermic group, no significant differences in sperm parameters and oxidative stress markers were shown after incubation with LPS in neat and selected sperms. Regarding samples from the non-leukospermic group, LPS reduced spermatozoa motility and vitality rates in selected sperm (P = 0.003; P = 0.004, respectively). A significant increase of MDA and CG levels was also detected (P = 0.01; P = 0.02, respectively). However, only the MDA levels were significantly increased (P = 0.01) in neat LPS-stimulated sperm. The same results were shown within the leukospermic group. The comparison between the two groups, leukospermic and non-leukospermic, in selected sperms showed a more important LPS effect in the leukospermic group significantly on motility and MDA rates (P = 0.006; P = 0.009, respectively). Furthermore, a significant decrease in reacted spermatozoa rate was detected in response to LPS in selected sperm samples from infertile men (P = 0.03). CONCLUSIONS: These findings indicate that human spermatozoa express TLR4 and respond to LPS stimulation with alterations in viability, motility, and the acrosome reaction implicating reactive oxygen species (ROS) production in sperm samples from infertile patients.

Induction of Epstein-Barr virus (EBV) lytic cycle in vitro causes lipid peroxidation, protein oxidation and DNA damage in lymphoblastoid B cell lines.

BACKGROUND: We investigated the oxidative modifications of lipids, proteins and DNA, potential molecular targets of oxidative stress, in two lymphoblastoid cell lines: B95-8 and Raji, after EBV lytic cycle induction. Conjugated dienes level was measured as biomarker of lipid peroxidation. Malondialdehyde adduct and protein carbonyl levels, as well as protein thiol levels were measured as biomarkers of protein oxidation. DNA fragmentation was evaluated as biomarker of DNA oxidation. RESULTS: After 48 h (peak of lytic cycle), a significant increase in conjugated dienes level was observed in B95-8 and Raji cell lines (p = 0.0001 and p = 0.019 respectively). Malondialdehyde adduct, protein carbonyl levels were increased in B95-8 and Raji cell lines after EBV lytic cycle induction as compared to controls (MDA-adduct: p = 0.008 and p = 0.006 respectively; Carbonyl: p = 0.003 and p = 0.0039 respectively). Proteins thiol levels were decreased by induction in B95-8 and Raji cell lines (p = 0.046; p = 0.002 respectively). DNA fragmentation was also detected in B95-8 and Raji cell lines after EBV lytic cycle induction as compared to controls. CONCLUSION: The results of this study demonstrate the presence of increased combined oxidative modifications in lipids, proteins in B95-8 and Raji cells lines after EBV lytic cycle induction. These results suggest that lipid peroxidation, protein oxidation and DNA fragmentation are generally induced during EBV lytic cycle induction and probably contribute to the cytopathic effect of EBV.

Characterization of an l-arabinose isomerase from the Lactobacillus plantarum NC8 strain showing pronounced stability at acidic pH.

Gene araA encoding the l-arabinose isomerase (l-AI) from Lactobacillus plantarum NC8 was cloned and expressed in Escherichia coli. It encodes a polypeptide of 474 residues having 55% identities with l-AIs from Bacillus stearothermophilus US100 and Thermus sp. IM6501. The active form of the purified recombinant l-AI NC8 enzyme is a hexamer composed of six identical 55-kDa subunits. The purified enzyme was optimally active at 60 degrees C and pH 7.5. It required divalent cations such as Co(2+) and Mn(2+) for maximal activity and thermostability. The l-AI NC8 was exceptionally active and stable at acidic pH. Indeed, it exhibited 68% of its maximal activity at pH 5.5 and retained 89% of activity after a 24-h incubation at pH 5. The apparent K(m) values of the enzyme for l-arabinose and d-galactose were 43.4 and 69.7 mM, respectively, and its catalytic efficiency was c. 10-fold higher for the physiological substrate l-arabinose (15.5 mM(-1) min(-1)) than d-galactose (1.6 mM(-1) min(-1)). The bioconversion yield of d-galactose to d-tagatose by the purified l-AI NC8 after 6 h at 60 degrees C was 30%.

Differential reactive oxygen species production of neutrophils and their oxidative damage in patients with active and inactive systemic lupus erythematosus.

OBJECTIVE: Increasing interest is given to the involvement of the innate immunity and especially Polymorphonuclear neutrophils (PMN) in the physiopathological process of inflammatory diseases such as systemic lupus erythematosus (SLE). Here, we investigated the oxidative burst and damages in SLE patients neutrophils, considering the two phases of the disease, the active and the remission/inactive states. METHODS: This study was conducted on 30 SLE patients and 23 healthy controls. The oxidative burst in neutrophils of SLE patients and controls was triggered by fMLP and TPA, while reactive oxygen species (ROS) production was evaluated using a chemiluminescence assay. Oxidative damages in neutrophils were assessed by measuring Free thiol groups level and carbonyl groups, as protein oxidative markers. The malondialdehyde (MDA) level informed about the lipid peroxidation (LPO) and the catalase activity indicated the antioxidant enzymatic activity. RESULT: Compared to controls, SLE patients exhibited a significantly increased level of ROS production concomitantly to a decreased response time. Their Neutrophils were characterized by a decreased level of MDA and high levels of protein oxidation as evidenced by increased carbonyl groups and decreased SH levels. The catalase activity was higher in SLE patients' neutrophils compared to controls. When patients were clustered according to the disease activity, PMN of patients in active phase showed, paradoxically, a lower ROS production and exhibited higher oxidative damages than the inactive group. CONCLUSION: Our results highlight an altered behavior of LES patients derived PMN particularly in the active phase of the disease. The evaluation of the redox status including the rate of ROS production could be a biological marker to follow the activity of the disease.

A comparative study of nuclear 8-hydroxyguanosine expression in Autoimmune Thyroid Diseases and Papillary Thyroid Carcinoma and its relationship with p53, Bcl-2 and Ki-67 cancer related proteins.

PURPOSE: To investigate whether the oxidative stress is involved in the evolution of Graves' disease (GD) and Hashimoto thyroiditis (HT) into Papillary Thyroid Carcinoma (PTC), 8-hydroxy-2'-deoxyguanosine (8-OHdG) and cancer related proteins (Bcl-2, p53 and Ki-67) expressions were evaluated in these pathologies. PATIENTS AND METHODS: Immunohistochemical method was applied on 25 thyroid tissues. Allred score (AS) serving to evaluate the immunostaining is based on a scale from 0 to 8. "Negligible expression" was assigned to a score of 0 to 2, "expression" and "overexpression" were attributed to a score of 3-5 and ≥6 respectively. RESULTS: PTC cancer cells exhibited 100% 8-OHdG "overexpression" compared to 87.5% in PTC non-malignant epithelial (NME) ones (p<0.05). Higher 8-OHdG AS was found in PTC NME cells compared to GD and HT (p<0.001, p<0.05 respectively). "Overexpression" of Bcl-2 was noted in all PTC cell types. Remarkably, just like the PTC cancer and NME cells 33.3% of HT and 50% of GD patients' revealed simultaneous "overexpression" of Bcl-2 and 8-OHdG in epithelial cells. No staining was detected for p53 in all pathologies. PTC lymphoid cells exhibited 100% "overexpression" for 8-OHdG and Bcl-2 with concomitant "negligible expression" for Ki-67 in 87.5% of patients. In contrast, HT lymphoid cells showed 22.2% "expression" and GD 62.5% "expression" and 12.5% "overexpression" of Ki-67. CONCLUSIONS: Simultaneous "overexpression" of 8-OHdG and Bcl-2 in GD and HT could be considered as prognostic markers while "negligible expression" of Ki-67 in PTC lymphoid cells suggests an anergic state favoring the tumor escapes from the immune system.

Proteins oxidation and autoantibodies' reactivity against hydrogen peroxide and malondialdehyde -oxidized thyroid antigens in patients' plasmas with Graves' disease and Hashimoto Thyroiditis.

The aim of this study was to evaluate proteins oxidation in plasmas of two autoimmune thyroid diseases (AITD): Graves' disease (GD) and Hashimoto Thyroiditis (HT), and to determine whether oxidative modification of thyroid antigens (T.Ag) enhanced the reactivity of autoantibodies in plasmas of AITD patients compared with the reactivity towards native T.Ag. Carbonyl and thiol groups and MDA-protein adducts were assessed spectrophotometric methods in plasmas of 74 AITD patients and 65 healthy controls. The reactivities immunoglobulin (Ig)G autoantibodies towards malondialdéhyde (MDA)-modified T.Ag, hydrogen peroxide (H2O2)-modified T.Ag, native T.Ag and native derm were checked by enzyme-linked immunosorbent assay (ELISA). Evaluation of oxidized proteins exhibited high levels of MDA bound to proteins and carbonyl groups, as well as reduced thiol level in plasmas of AITD patients by comparison to healthy controls (p < 0.05). The ELISA test showed that AITD patients' plasmas' reactivity to native T.Ag was significantly increased to the reactivity towards native derm, whereas, no differences were found in the reactivity to native T.Ag and derm in controls plasmas. In addition, treatment of T.Ag by oxidants revealed enhanced reactivity of IgG circulating autoantibodies against H2O2-oxidized T.Ag compared to native ones (p < 0.001) in plasmas of both AITD. Also, reactivity's to MDA-oxidized T.Ag in GD plasmas decreased compared to native ones (p < 0.05) and no changes were noted for HT. Pearson correlation study resulted in positive correlation between reactivity's to H2O2-oxidized T.Ag and free triodotyronine level in GD patients (r = 0.42, p < 0.05) in one hand and thyroid stimulating hormone level in HT patients in the other (r = 0.65, p < 0.001). The data suggest that high production of H2O2 probably occurred during hormone synthesis could contribute to protein oxidation in AITD and to create neoepitopes responsible for autoantibody reactivity's to H2O2-oxidized T.Ag enhancement. These results provide support to the involvement of oxidative stress in AITD development and/or exacerbation.

Lipid peroxidation, proteins modifications, anti-oxidant enzymes activities and selenium deficiency in the plasma of hashitoxicosis patients.

OBJECTIVES: The aim of this study was to explore the oxidative stress profile in hashitoxicosis (HTX) and to compare it with that of healthy subjects. PATIENTS AND METHODS: Spectrophotometric methods were used to evaluate the oxidative stress markers. The selenium level was investigated by atomic absorption. RESULTS: High levels of thiobarbituric acid reactive species (TBARS) and conjugated dienes were found in HTX patients (p = 0.034 and p = 0.043, respectively) compared with healthy controls. For antioxidant enzymes, superoxide dismutase (SOD) and catalase activities increased, whereas that of glutathione peroxidase (GPx) decreased (p = 0.000, p = 0.014, p = 0.000, respectively) compared with controls. A reduction in the level of selenium (p = 0.029) and thiol groups (p = 0.008) were shown in patients; however, levels of carbonyl group and malondialdehyde (MDA) protein adducts decreased (p = 0.000) compared with controls. Positive correlation was shown between levels of free thyroxine (FT4) and TBARS (r = 0.711, p = 0.048) and between FT4 level and SOD activity (r = 0.713, p = 0.047). Conversely, GPx activity presented a negative correlation with FT4 and free triiodothyronine (FT3) levels (r = -0.934, p = 0.001; r = -0.993, p = 0.000, respectively). In addition, GPx activity showed positive correlation with selenium level (r = 0.981, p = 0.019) and the FT3 level correlated negatively with the level of thiol groups (r = -0.892, p = 0.017). CONCLUSIONS: This study shows the presence of an oxidative stress and selenium deficiency in HTX patients and suggests that the hyperthyroid state is strongly implicated in the establishment of this disturbed oxidative profile.

Reactive oxygen species production and antioxidant enzyme expression after Epstein-Barr virus lytic cycle induction in Raji cell line.

In a previous study, we have described oxidative stress during Epstein-Barr virus lytic cycle induction. Oxidative stress was evidenced by the observed high MDA levels and the decreased activities of antioxidant enzymes. We hypothesised that the lower activities of the antioxidant enzymes decrease were the result of either the excessive production of reactive oxygen radical species (ROS) or a negative regulation of the antioxidant enzyme gene expressions. In an attempt to clarify this situation, EBV lytic cycle was induced in Raji cell line by a non-stressing dose of 12-0-tetradecanoylphorbol-13-acetate. BZLF-1, superoxide dismutase, and catalase gene expressions were then analysed using semi-quantitative RT-PCR, simultaneously at a kinetic of 6, 12, 24, 36, and 48 h. ROS production was evaluated by chemiluminescence. A study was conducted to establish whether ROS production, BZLF-1, and the expression of antioxidant genes were inter-correlated. Induction of the lytic cycle resulted in increased expressions of the genes of superoxide dismutase and catalase, which began at 24 h (p < 0.05) and reached a peak at 48 h (p < 0.05). Significant increases of the ROS levels were observed in TPA-treated Raji cell line at 12 h, as compared with untreated cells, reaching a peak at 48 h after EBV lytic cycle induction. ROS production correlates positively with BZLF-1, SOD, and CAT gene expressions (p < 0.05; r = 0.913, r = 0.978, and r = 0.955, respectively). A positive correlation was also observed between BZLF-1 and antioxidant gene expressions (p < 0.05; r = 0.961 and r = 0.987, respectively). In conclusion, the observed increases of the SOD and CAT gene expressions eliminate the hypothesis of a repression of the respective genes during the induction of the lytic cycle. On the other hand, the observed direct correlation between the BZLF-1 gene expression and the ROS production is indicative of a role of this gene in oxidative stress.

A comparative study of the oxidative profile in Graves' disease, Hashimoto's thyroiditis, and papillary thyroid cancer.

The aim of this study was to evaluate and compare the oxidative profiles of three thyroid disorders: Graves' disease (GD), Hashimoto thyroiditis (HT), and papillary thyroid cancer (PTC). Malondialdehyde levels (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) activities were examined in the plasma of 52 patients (29 untreated HT, 16 untreated GD, and 7 PTC who underwent surgical therapy). Results were compared with those of 30 healthy controls and among the three groups of patients. The GD, HT, and PTC patients exhibited increased plasma MDA levels and SOD activities compared with the controls (p < 0.05, p < 0.05, and p < 0.001, respectively). CAT activities significantly increased only for the PTC and HT patients (p < 0.001 and p < 0.05, respectively), whereas GPx activities significantly decreased only in the GD and PTC (p < 0.05 and p < 0.01, respectively). The comparison among the three groups of patients has shown increased MDA level and SOD activity for the PTC patients as compared to the GD patients (p < 0.01 and p < 0.001, respectively). Compared with HT, PTC patients exhibited significant higher MDA level, SOD, and CAT activities and a significant lower GPx activity (p < 0.01, p < 0.001, p < 0.05, and p < 0.05, respectively). No significant discrepancies were noted between the GD and HT patients. Our results have clearly shown an oxidative profile that is highly disturbed for the PTC patients as compared to those of autoimmune disorders. Future studies are needed to determine whether or not the oxidative stress has a prognostic value in this pathology.