The Natural Stilbenoid Piceatannol Decreases Activity and Accelerates Apoptosis of Human Neutrophils: Involvement of Protein Kinase C

Neutrophils are able to release cytotoxic substances and inflammatory mediators, which, along with their delayed apoptosis, have a potential to maintain permanent inflammation. Therefore, treatment of diseases associated with chronic inflammation should be focused on neutrophils; formation of reactive oxygen species and apoptosis of these cells represent two promising targets for pharmacological intervention. Piceatannol, a naturally occurring stilbenoid, has the ability to reduce the toxic action of neutrophils. This substance decreased the amount of oxidants produced by neutrophils both extra- and intracellularly. Radicals formed within neutrophils (fulfilling a regulatory role) were reduced to a lesser extent than extracellular oxidants, potentially dangerous for host tissues. Moreover, piceatannol did not affect the phosphorylation of p40phox—a component of NADPH oxidase, responsible for the assembly of functional oxidase in intracellular (granular) membranes. The stilbenoid tested elevated the percentage of early apoptotic neutrophils, inhibited the activity of protein kinase C (PKC)—the main regulatory enzyme in neutrophils, and reduced phosphorylation of PKC isoforms α, βII, and δ on their catalytic region. The results indicated that piceatannol may be useful as a complementary medicine in states associated with persisting neutrophil activation and with oxidative damage of tissues

The Natural Stilbenoid Piceatannol Decreases Activity and Accelerates Apoptosis of Human Neutrophils: Involvement of Protein Kinase C

Neutrophils are able to release cytotoxic substances and inflammatory mediators, which, along with their delayed apoptosis, have a potential to maintain permanent inflammation. Therefore, treatment of diseases associated with chronic inflammation should be focused on neutrophils; formation of reactive oxygen species and apoptosis of these cells represent two promising targets for pharmacological intervention. Piceatannol, a naturally occurring stilbenoid, has the ability to reduce the toxic action of neutrophils. This substance decreased the amount of oxidants produced by neutrophils both extra-and intracellularly. Radicals formed within neutrophils (fulfilling a regulatory role) were reduced to a lesser extent than extracellular oxidants, potentially dangerous for host tissues. Moreover, piceatannol did not affect the phosphorylation of p40 phox -a component of NADPH oxidase, responsible for the assembly of functional oxidase in intracellular (granular) membranes. The stilbenoid tested elevated the percentage of early apoptotic neutrophils, inhibited the activity of protein kinase C (PKC)-the main regulatory enzyme in neutrophils, and reduced phosphorylation of PKC isoforms , II, and on their catalytic region. The results indicated that piceatannol may be useful as a complementary medicine in states associated with persisting neutrophil activation and with oxidative damage of tissues

Reduction of oxidative stress in adjuvant arthritis. Comparison of efficacy of two pyridoindoles: stobadine dipalmitate and SMe1.2HCl

The aim of this study was to evaluate the therapeutic potential of oxidative stress (OS) reduction by using pyridoindole (PI) antioxidants in adjuvant arthritis (AA). The substances tested were stobadine dipalmitate (STB) and SMe1. AA was used as animal model. The experiments included healthy animals, control arthritic animals and arthritic animals with administration of PI in the oral daily dose of 15 mg/kg b.m during 28 experimental days. The rats were sacrificed on day 28. Clinical and biochemical parameters were determined. The effect of PI administration was evaluated on the basis of the following parameters: (a) arthritis (volume of hind paws - HPW, change of animal body mass - CBM), (b) OS (chemiluminescence of whole blood - CWB, levels of thiobarbituric acid reacting substance - TBARS and of HNE- and MDA-protein adducts in plasma and activity of γ-glutamyltransferase (GGT) in hind paw joint homogenates). The PI studied significantly increased the CBM of animals and corrected the HPW. STB also significantly decreased the activity of GGT in joint homogenates. SMe1 was more effective in decreasing plasmatic TBARS levels, but STB was more effective in reducing plasmatic HNE- and MDA-protein adducts. The assay for HNE- and MDA-adducts in plasma as a function of time was applied for the first time in AA. STB markedly decreased spontaneous and PMA-stimulated CWB and reduced neutrophil count. In summary, STB was more effective than SMe1 in reducing OS in AA. Our results showed that the reduction of OS in arthritis also corrected the clinical manifestations of the disease

The role of redox imbalance in relation to immunological process in adjuvant arthritis

The model of adjuvant arthritis (AA) is well characterized concerning the immunological processes involved. However knowledge on the participation of redox imbalance in the progression of AA is scarce. The link between oxidative stress (OS) and immunological status in arthritis should be more precisely investigated. In our experiments, we focused on AA development in the time domain. AA was induced in rats by a single intradermal injection of Mycobacterium butyricum in incomplete Freund’s adjuvant. All experiments included healthy animals (HC) and arthritic animals not treated. We confirmed that the clinical parameters hind paw volume and body weight became significantly modified starting around day 14 after AA induction and this change was maintained until the end of the experiment (day 28). We obtained a good agreement of clinical parameters with parameters of OS. Measurements of plasmatic protein carbonyls revealed damage of proteins caused by OS. Progression of lipid peroxidation in AA was described by analysis of TBARS, HNE- /MDA-protein adducts and F2 isoprostane levels in plasma. Total antioxidant status analyzed in plasma was decreased significantly in both the acute (day 21) and the subchronic phase (day 28) of AA. Further we focused on evaluating CoQ9 plasmatic levels. The arthritic process increased significantly the level of CoQ9 in comparison to HC. Evidently, the arthritic process stimulates the synthesis of CoQ9 and its transport to plasma. In the model of AA, we observed already on experimental day 7 that AA was accompanied by an increased number of neutrophils in blood and by a more pronounced spontaneous as well as phorbol myristate acetate stimulated chemiluminescence. As the changes in neutrophils occur before the clinical parameter HPV starts to be increased, for further evaluation of neutrophil functionality we chose experimental day 7. The functionality of peripheral blood neutrophils in AA was described by phagocytosis, oxidative burst and metabolic activity. Both phagocytosis and oxidative burst were increased due to arthritis, and that despite the decreased metabolic activity. Analysis of OS in tissue showed changed GGT activity in spleen and joint homogenate accompanied by increased chemiluminescence. The OS parameters were in close relationship with time profiles of selected cytokines, chemokine MCP-1 and of C-reactive protein levels in plasma. Measurements of the immunoregulatory index in peripheral blood and lipoxygenase tissue activity (lung, liver) were also included. Our observations have evidenced the importance of pharmacological regulation of redox imbalance in arthritis. (VEGA 2/0090/08, COST B35, APVV-51-017905, APVV-21-055205