Inhibition of oxidative stress in brain during rat adjuvant arthritis by carnosine, trolox and novel trolox-carnosine

Carnosine (CARN) is an anti-glycating agent able to quench superoxide, and to neutralize 4-hydroxynonenal. Trolox-carnosine (CARN-T) was synthesized because of its resistance against degradation and to improve CARN antioxidant capacity. We evaluated the impact of trolox (TRO), CARN and its derivative CARN-T on oxidative stress (OS) in brain during rat adjuvant arthritis (AA). The experiments were done on healthy, control arthritic and arthritic animals with administration of CARN 150 mg/kg b.w., TRO 41 mg/kg b.w. and CARN-T 75 mg/kg b.w. in a daily dose during 28 days. Antioxidants did not affect the body weight on day 14, but on day 28 TRO enhanced the weight reduction. On day 14 and 28 CARN-T and TRO reduced arthritic score. IL-1beta, MCP-1 and MMP-9 were measured in plasma on day 14. MCP-1 was decreased by CARN-T and TRO. All antioxidants reduced IL-1beta and MMP-9 levels. Malondialdehyde, 4-hydroxynonenal and protein carbonyls were increased in brain. CARN, CARN-T and TRO prevented higher lipid and protein oxidation in brain. CARN and CARN-T caused no weight reduction like TRO that has an advantage in inflammatory arthritis. Moreover the antioxidants administered had a similar therapeutic effects on arthritic score, markers of inflammation in plasma and OS in brain.

Effect of methotrexate on inflammatory cells redistribution in experimental adjuvant arthritis

The aim of this study was to evaluate the morphological changes in the spleen, the thymus and the knee joints of rats with experimental adjuvant arthritis induced by Mycobacterium butyricum in the incomplete Freund's adjuvant and the effect of treatment with methotrexate (MTX). Particular attention was aimed on the redistribution of granulocytes in the tissues during the inflammatory process. Clinical parameters, e.g., joint edema, body weight and of gamma glutamyl transferase (GGT) activity as an inflammatory marker, have also been determined. Induction of adjuvant arthritis caused a significant decrease in granulocyte number in the spleen and vice versa a significant increase in the knee joints, but without significant changes in the thymus. Treatment with methotrexate reversed this phenomenon by increasing the granulocyte number in the spleen and decreasing it in knee joints. MTX decreased the joint edema as well as the activity of GGT in the spleen, modified the size of the white pulp of the spleen and increased the cortex/medulla ratio in the thymus. The observed changes support the anti-inflammatory and immunomodulatory properties of MTX supporting its use as the first-line medication in patients with rheumatoid arthritis.

Pharmacological regulation of neutrophil activity and apoptosis: Contribution to new strategy for modulation of inflammatory processes

Novel strategies of antiinflammatory therapy are based upon pharmacological agents capable to enhance the resolution - i.e. the termination of the beneficial inflammation before it may turn into an adverse chronic stage. In contrast to the current therapy, which antagonises the formation of proinflammatory mediators, the "proresolving" therapy promotes natural antiinflammatory processes. It is likely that several drugs and phytochemicals would act in this way, but this point has not been investigated and thus might be totally overlooked. In this paper, effects of curcumin (diferuloylmethane) were analysed, considering the ability of this natural compound to affect resolution of inflammation through modulation of its important inputs - activity and apoptosis of neutrophils. The presented data indicate that, besides its well-known ability to suppress mechanisms engaged at the onset and progression of inflammation, curcumin could support resolution of inflammation through decreased activity and enhanced apoptosis of neutrophils. This substance decreased the formation of oxidants in neutrophils, both under in vitro conditions and after oral administration to arthritic rats. Moreover, curcumin accelerated spontaneous apoptosis of neutrophils, as indicated by increased externalisation of phosphatidylserine, by intercalation of propidium iodide and by enhanced activity of the executioner caspase-3.

Study of new ways of supplementary and combinatory therapy of rheumatoid arthritis with immunomodulators. Glucomannan and Imunoglukán®in adjuvant arthritis

We studied the anti-arthritic activity of glucomannan (GM) isolated from Candida utilis and of Imunoglukán®, a beta-(1,3/1,6)-d-glucan (IMG) isolated from Pleurotus ostreatus. Adjuvant arthritis (AA) was induced intradermally by the injection of Mycobacterium butyricum in incomplete Freund’s adjuvant to Lewis rats. Blood for biochemical and immunological analysis was collected on experimental days 1, 14, 21, and 28. A clinical parameter – hind paw volume (HPV) – was also measured. The detection of IL-1 alpha, IL-4, TNF alpha, and MCP-1 was done by immunoflowcytometry. On day 28 – the end of the experiment – we determined spectrophotometrically: the total anti-oxidant status (TAS) of plasma samples along with thiobarbituric acid-reacting substances (TBARS) levels in plasma and we assessed the activity of gamma-glutamyl transferase (GGT) in hind paw joint homogenate. The experiments included healthy animals, arthritic animals without treatment, and arthritic animals with administration of glucomannan (GM-AA) in the oral daily dose of 15 mg/kg b.w. and of IMG (IMG-AA) in the oral daily dose of 2 mg/kg b.w. The progress of AA was manifested by all parameters monitored. Both substances had beneficial effects on HPV, TBARS levels, GGT activity, and TAS levels. For cytokine assessment, only IMG-AA samples were selected, considering the significant HPV improvement accompanied with the observed anti-oxidant action. IMG administration had a positive immunomodulating effect on all cytokine plasma levels measured, changed markedly due to arthritis progression. Thus, IMG may be considered as a candidate for combinatorial therapy of rheumatoid arthritis.

Glucomannan reduces neutrophil free radical production in vitro and in rats with adjuvant arthritis

The effect of glucomannan (GM), a natural polysaccharide isolated from the yeast Candida utilis, on reactive oxygen species (ROS) generation in human neutrophils in vitro and in rats with Mycobacterium butyricum induced adjuvant arthritis (AA) was tested by the luminol/isoluminol-enhanced chemiluminescence (CL) method. In vitro, GM (500 microg/ml) significantly decreased spontaneous CL of human whole blood, while PMA (4beta-phorbol-12beta-myristate-alpha13acetate)-stimulated CL was decreased by GM in the concentrations of 100 and 500 microg/ml. To specify the site of action of GM, its effect on extra- and intracellular ROS generation in isolated neutrophils was evaluated. GM significantly decreased spontaneous and PMA-stimulated CL and it was more effective extracellularly than intracellularly. In vivo experiments included healthy animals as controls, arthritic animals without any drug administration, and arthritic animals with GM administration (once daily in the oral dose of 15 mg/kg, over a period of 28 days). On day 28, CL in whole blood, spleen and joint was monitored. Arthritic animals treated with GM showed decrease in spontaneous and PMA-stimulated CL of whole blood as well as CL of the joint, in comparison with untreated animals. The obtained findings demonstrated an antioxidant effect of GM in vitro and in rats with AA, which may be due to its free radical scavenger activity and to interaction with different receptors and/or modulation of postreceptor intracellular signalling pathways. The specific physicochemical parameters, such as structure of GM, its low molecular weight and good water solubility, play an important role in the above effects.

Mesenteric ischemia/reperfusion-induced intestinal and vascular damage: effect of stobadine

This study examined the effects of the pyridoindole compound stobadine on intestinal and vascular injury following mesenteric ischemia/reperfusion (I/R) in rats. Ischemia was induced by occlusion of the superior mesenteric artery (SMA) for 60 min, followed by 30 min reperfusion. To characterize gut impairment, some parameters of intestinal damage and biochemical variables, such as GSH content, activity of a lysosomal enzyme N-acetyl-beta-D-glucuronidase and activity of gamma-glutamyl transpeptidase, were determined. Vascular I/R-induced damage was evaluated as changes in acetylcholine evoked relaxation of mesenteric artery rings under isometric conditions. A method of amplified chemiluminescence (CL) was used to detect production of reactive oxygen species (ROS). Following I/R, pronounced intestinal injury of various intensities was observed, with maximal changes occurring in the terminal ileum. The effect of I/R was expressed mainly as increased vascular permeability, with protein leakage and subsequent hemorrhagic injury of the intestine as well as impaired endothelium-dependent SMA relaxation. Vessel dysfunction was manifested by a decrease of the maximal relaxation response to acetylcholine. An increase of CL, indicative of increased ROS production, was observed in both intestinal and vascular tissue. A novel antioxidant, stobadine, was found to reduce the increased vascular permeability and the extent of small intestine injury caused by I/R, to improve biochemical alterations accompanying I/R, to protect endothelial-dependent relaxation of mesenteric arteries, and to attenuate the CL response. The observed beneficial effect of stobadine indicates its possible application in the preventive and/or therapeutic approach to I/R-induced pathologies.

Association between tissue gamma-glutamyl-transferase and clinical markers of adjuvant arthritis in Lewis rats

OBJECTIVES

To assess glucomannan and pyridoindole derivatives for possible antioxidant therapy of rheumatoid arthritis (RA) by using the model of adjuvant arthritis (AA). We evaluated the association between clinical markers of the adjuvant arthritis model used - increase of hind paw volume (HPV), changes of body mass (CBM), and tissue gamma-glutamyl transferase (GGT) activity assessed in the spleen and the joint.

METHODS

AA was induced in Lewis rats by a single intradermal injection of Mycobacterium butyricum. The two independent experiments included healthy animals as reference, arthritic animals without any drug administration and arthritic animals with pyridoindole administration in one dose tested or glucomannan administration in two different doses. The pyridoindoles (PI) studied were stobadine dipalmitate and its derivatives SMe1.2HCl and SMe1EC2.HCl. We monitored CBM and HPV twice a week. Parameter of inflammation - GGT in the spleen and the joint from the hind paw (cartilage and soft tissue without bone) was determined on day 28. The correlation coefficient of GGT activity with CBM and with HPV was calculated.

RESULTS

The antioxidants tested were effective in slowing down the progress of adjuvant arhritis. The association between tissue GGT activity and the clinical marker of adjuvant arthritis - CBM was higher in the spleen than in the joint. The other clinical marker assessed - HPV, gave a better association with GGT activity measured in the joint than in the spleen.

CONCLUSIONS

It may be concluded that GGT activity in tissues as the spleen and the joint could provide a simple and inexpensive marker for AA and RA development at systemic as well as local level; all the antioxidants studied were effective in slowing down the progress of adjuvant arhritis.

Gut and vessel alterations induced by mesenteric ischaemia/reperfusion in rats

A rat model of transient occlusion of the superior mesenteric artery was used to study the intestinal and vascular injury induced by ischaemia/ reperfusion (I/R). A pronounced intestinal injury was observed, ranging from hyperaemia to severe haemorrhagic necrosis and bleeding. The length of the damaged intestinal segments reached 58.6% of the small intestine with a decrease of the wet weight in the I/R group. Sham operation resulted in 100% survival, I/R decreased survival to 40% after 24 h. Following I/R a significant increase of vascular permeability was observed in the small intestine. Gamma-glutamyl transpeptidase activity decreased aborally in sham operated rats and I/R reduced it further in all parts of the small intestine. I/R resulted in damaged endothelium-dependent relaxation of mesenteric artery rings. This was manifested by decreased maximal responses of arterial preparations to acetylcholine as well as decreased pD2 values. The results confirmed and specified the presumed effect of I/R on the small intestine and on vascular functions.

Contribution to safe anti-inflammatory therapy with indomethacin

Non-steroidal anti-inflammatory drugs possess not only therapeutic but also adverse effects, mainly on the gastrointestinal tract. The aim of this pilot study was to establish the ulcerogenic dose caused by daily administration of indomethacin to male Lewis rats. Further, the model of rat adjuvant arthritis (AA) was used to evaluate the protective effect of stobadine dipalmitate against indomethacin-induced gastroenteropathy. Indomethacin was administered subcutaneously in the daily dose of 5, 7, 10, 20 and 30 mg/kg b.w. Survival of the animals and damage of gastric and intestinal mucosa were monitored, and some biochemical parameters were determined. In AA rats stobadine dipalmitate was administered orally in the daily dose of 15 mg/kg. For the chronical experiments on AA rats the subcutaneous indomethacin dose of 5 mg/kg was selected as the therapeutic dose and the dose of 7 mg/kg was chosen as the adequate dose for gastropathy induction. The additive adverse effect of arthritis induction and indomethacin administration was demonstrated on the basis of gastric mucosa damage observations. The supposed stobadine gastro-protection was not confirmed.

Pharmacokinetic study of stobadine

The aim of this paper is to provide a brief overview of most important results of stobadine kinetic studies in rats, dogs, and human volunteers. In these studies, stobadine dihydrochloride and stobadine dipalmitate was used for intravenous and oral administration, respectively. To evaluate kinetic properties of stobadine and its metabolites, TLC, HPLC, GLC, GC-MS, radiometric, and fluorometric methods were developed and used.