Effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs on the production of reactive oxygen species by activated rat neutrophils.

The release of reactive oxygen specie (ROS) by activated neutrophil is involved in both the antimicrobial and deleterious effects in chronic inflammation. The objective of the present investigation was to determine the effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs (NSAIDs) on the production of ROS by stimulated rat neutrophils. Diclofenac (3.6 microM), indomethacin (12 microM), naproxen (160 microM), piroxicam (13 microM), and tenoxicam (30 microM) were incubated at 37 masculineC in PBS (10 mM), pH 7.4, for 30 min with rat neutrophils (1 x 10(6) cells/ml) stimulated by phorbol-12-myristate-13-acetate (100 nM). The ROS production was measured by luminol and lucigenin-dependent chemiluminescence. Except for naproxen, NSAIDs reduced ROS production: 58 +/- 2% diclofenac, 90 +/- 2% indomethacin, 33 +/- 3% piroxicam, and 45 +/- 6% tenoxicam (N = 6). For the lucigenin assay, naproxen, piroxicam and tenoxicam were ineffective. For indomethacin the inhibition was 52 +/- 5% and diclofenac showed amplification in the light emission of 181 +/- 60% (N = 6). Using the myeloperoxidase (MPO)/H2O2/luminol system, the effects of NSAIDs on MPO activity were also screened. We found that NSAIDs inhibited both the peroxidation and chlorinating activity of MPO as follows: diclofenac (36 +/- 10, 45 +/- 3%), indomethacin (97 +/- 2, 100 +/- 1%), naproxen (56 +/- 8, 76 +/- 3%), piroxicam (77 +/- 5, 99 +/- 1%), and tenoxicam (90 +/- 2, 100 +/- 1%), respectively (N = 3). These results show that therapeutic levels of NSAIDs are able to suppress the oxygen-dependent antimicrobial or oxidative functions of neutrophils by inhibiting the generation of hypochlorous acid.

Indole ring oxidation by activated leukocytes prevents the production of hypochlorous acid.

Hypochlorous acid (HOCl) released by activated leukocytes has been implicated in the tissue damage that characterizes chronic inflammatory diseases. In this investigation, 14 indole derivatives, including metabolites such as melatonin, tryptophan and indole-3-acetic acid, were screened for their ability to inhibit the generation of this endogenous oxidant by stimulated leukocytes. The release of HOCl was measured by the production of taurine-chloramine when the leukocytes (2 x 10(6) cells/mL) were incubated at 37 degrees C in 10 mM phosphate-buffered saline, pH 7.4, for 30 min with 5 mM taurine and stimulated with 100 nM phorbol-12-myristate acetate. Irrespective of the group substituted in the indole ring, all the compounds tested including indole, 2-methylindole, 3-methylindole, 2,3-dimethylindole, 2,5-dimethylindole, 2-phenylindole, 5-methoxyindole, 6-methoxyindole, 5-methoxy-2-methylindole, melatonin, tryptophan, indole-3-acetic acid, 5-methoxy-2-methyl-3-indole-acetic acid, and indomethacin (10 microM) inhibited the chlorinating activity of myeloperoxidase (MPO) in the 23-72% range. The compounds 3-methylindole and indole-3-acetic acid were chosen as representative of indole derivatives in a dose-response study using purified MPO. The IC50 obtained were 0.10 +/- 0.03 and 5.0 +/- 1.0 microM (N = 13), respectively. These compounds did not affect the peroxidation activity of MPO or the production of superoxide anion by stimulated leukocytes. By following the spectral change of MPO during the enzyme turnover, the inhibition of HOCl production can be explained on the basis of the accumulation of the redox form compound-II (MPO-II), which is an inactive chlorinating species. These results show that indole derivatives are effective and selective inhibitors of MPO-chlorinating activity.

In vitro nanotoxicity of single-walled carbon nanotube-dendrimer nanocomplexes against murine myoblast cells.

Single-wall carbon nanotubes (SWCNTs) and polyamidoamine dendrimers (PAMAM) have been proposed for a variety of biomedical applications. The combination of both molecules makes this new composite nanomaterial highly functionalizable and versatile to theranostic and drug-delivery systems. However, recent toxicological studies have shown that nanomaterials such as SWCNTs and PAMAM may have high toxicity in biological environments. Aiming to elucidate such behavior, in vitro studies with different cultured cells have been conducted in the past few years. This study focuses on the effects of SWCNT-PAMAM nanomaterials and their individual components on the C2C12 murine cell line, which is a mixed population of stem and progenitor cells. The interactions between the cells and the nanomaterials were studied with different techniques usually employed in toxicological analyses. The results showed that SWCNT-PAMAM and PAMAM inhibited the proliferation and caused DNA damage of C2C12 cells. Data from flow cytometry revealed a less toxicity in C2C12 cells exposed to SWCNT compared to the other nanomaterials. The results indicated that the toxicity of SWCNT, SWCNT-PAMAM and PAMAM in C2C12 cells can be strongly correlated with the charge of the nanomaterials.

Phagocytosis, oxidative burst, and produced reactive species are affected by iron deficiency anemia and anemia of chronic diseases in elderly.

Iron and oxidative stress have a regulatory interplay. During the oxidative burst, phagocytic cells produce free radicals such as hypochlorous acid (HOCl). Nevertheless, scarce studies evaluated the effect of either iron deficiency anemia (IDA) or anemia of chronic disease (ACD) on phagocyte function in the elderly. The aim of the present study was to determine the oxidative burst, phagocytosis, and nitric oxide (*NO) and HOCl, reactive species produced by monocytes and neutrophils in elderly with ACD or IDA. Soluble transferrin receptor, serum ferritin, and soluble transferrin receptor/log ferritin (TfR-F) index determined the iron status. The study was constituted of 39 patients aged over 60 (28 women and 11 men) recruited from the Brazilian Public Health System. Oxidative burst fluorescence intensity per neutrophil in IDA group and HOCl generation in both ACD and IDA groups were found to be lower (p < 0.05). The percentages of neutrophils and monocytes expressing phagocytosis in ACD group were found to be higher (p < 0.05). There was an overproduction of *NO from monocytes, whereas the fundamental generation of HOCl appeared to be lower. Phagocytosis, oxidative burst, and *NO and HOCl production are involved in iron metabolism regulation in elderly patients with ACD and IDA.

Indole ring oxidation by activated leukocytes prevents the production of hypochlorous acid

Hypochlorous acid (HOCl) released by activated leukocytes has been implicated in the tissue damage that characterizes chronic inflammatory diseases. In this investigation, 14 indole derivatives, including metabolites such as melatonin, tryptophan and indole-3-acetic acid, were screened for their ability to inhibit the generation of this endogenous oxidant by stimulated leukocytes. The release of HOCl was measured by the production of taurine-chloramine when the leukocytes (2 x 10(6) cells/mL) were incubated at 37°C in 10 mM phosphate-buffered saline, pH 7.4, for 30 min with 5 mM taurine and stimulated with 100 nM phorbol-12-myristate acetate. Irrespective of the group substituted in the indole ring, all the compounds tested including indole, 2-methylindole, 3-methylindole, 2,3-dimethylindole, 2,5-dimethylindole, 2-phenylindole, 5-methoxyindole, 6-methoxyindole, 5-methoxy-2-methylindole, melatonin, tryptophan, indole-3-acetic acid, 5-methoxy-2-methyl-3-indole-acetic acid, and indomethacin (10 æM) inhibited the chlorinating activity of myeloperoxidase (MPO) in the 23-72 percent range. The compounds 3-methylindole and indole-3-acetic acid were chosen as representative of indole derivatives in a dose-response study using purified MPO. The IC50 obtained were 0.10 ± 0.03 and 5.0 ± 1.0 æM (N = 13), respectively. These compounds did not affect the peroxidation activity of MPO or the production of superoxide anion by stimulated leukocytes. By following the spectral change of MPO during the enzyme turnover, the inhibition of HOCl production can be explained on the basis of the accumulation of the redox form compound-II (MPO-II), which is an inactive chlorinating species. These results show that indole derivatives are effective and selective inhibitors of MPO-chlorinating activity.

Effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs on the production of reactive oxygen species by activated rat neutrophils

The release of reactive oxygen specie (ROS) by activated neutrophil is involved in both the antimicrobial and deleterious effects in chronic inflammation. The objective of the present investigation was to determine the effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs (NSAIDs) on the production of ROS by stimulated rat neutrophils. Diclofenac (3.6 µM), indomethacin (12 µM), naproxen (160 µM), piroxicam (13 µM), and tenoxicam (30 µM) were incubated at 37°C in PBS (10 mM), pH 7.4, for 30 min with rat neutrophils (1 x 10(6) cells/ml) stimulated by phorbol-12-myristate-13-acetate (100 nM). The ROS production was measured by luminol and lucigenin-dependent chemiluminescence. Except for naproxen, NSAIDs reduced ROS production: 58 ± 2 percent diclofenac, 90 ± 2 percent indomethacin, 33 ± 3 percent piroxicam, and 45 ± 6 percent tenoxicam (N = 6). For the lucigenin assay, naproxen, piroxicam and tenoxicam were ineffective. For indomethacin the inhibition was 52 ± 5 percent and diclofenac showed amplification in the light emission of 181 ± 60 percent (N = 6). Using the myeloperoxidase (MPO)/H2O2/luminol system, the effects of NSAIDs on MPO activity were also screened. We found that NSAIDs inhibited both the peroxidation and chlorinating activity of MPO as follows: diclofenac (36 ± 10, 45 ± 3 percent), indomethacin (97 ± 2, 100 ± 1 percent), naproxen (56 ± 8, 76 ± 3 percent), piroxicam (77 ± 5, 99 ± 1 percent), and tenoxicam (90 ± 2, 100 ± 1 percent), respectively (N = 3). These results show that therapeutic levels of NSAIDs are able to suppress the oxygen-dependent antimicrobial or oxidative functions of neutrophils by inhibiting the generation of hypochlorous acid.