ABSTRACT
The plant amino acid L-mimosine has recently been suggested to inhibit cells at a regulatory step in late G1 phase before establishment of active DNA replication forks. In addition, L-mimosine is an extremely effective inhibitor of DNA replication in chromosomes of mammalian nuclei. In this work, the effect of L-mimosine on chronic inflammation induced by dorsal injections of 0.2 ml of a 1:40 saturated crystal solution of potassium permanganate in mice, was studied. Seven days afterwards, all mice developed a subcutaneous granulomatous tissue indicative of chronic inflammatory response at the site of infection. The intraperitoneal administration of L-mimosine (200 microg/dose) to the potassium permanganate treated mice for 5 consecutive days (the first at the same time of inoculation of the KMnO4), produced a significant decrease in size and weight of the granuloma when compared to mice not treated with L-mimosine (controls). In addition, in all mice treated with L-mimosine, there was a strong inhibition of tumor necrosis factor alpha that was revealed in the serum (P<0.05) and in the minced granulomas. Interleukin-6 was not detected in the serum of treated and untreated mice. These findings show for the first time, that L-mimosine may have an anti-inflammatory effect on chronic inflammation and an inhibitory effect on tumor necrosis factor alpha and interleukin-6 generation in supernatant fluids of minced granulomas.
Subject(s)
Disease Models, Animal , Granuloma/drug therapy , Mimosine/therapeutic use , Potassium Permanganate/toxicity , Animals , Chronic Disease , Granuloma/chemically induced , Granuloma/metabolism , Male , Mice , Mice, Inbred BALB C , Mimosine/pharmacology , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Tumor Necrosis Factor-alpha/metabolismABSTRACT
Monocyte chemotactic protein-1 (MCP-1) is a proinflammatory cytokine that attracts and activates specific types of leucocytes. The purpose of this work was to analyse the generation of MCP-1 and mRNA transcript in a model of chronic inflammation using a granulomatous tissue induced by potassium permanganate (KMnO4; water soluble crystals). The data presented here shows that MCP-1 is generated in granuloma tissue and its level was strongly increased by i.p. injections of lipopolysaccharide (LPS) and inhibited in rats treated with injections of dexamethasone, 18 hr before the animals were killed. In histological studies LPS and dexamethasone increased and decreased, respectively, the recruitment of mononuclear cells in the granuloma tissue compared with the control granulomas from phosphate-buffered saline (PBS)-treated animals. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for mRNA extraction and cDNA synthesis. mRNA MCP-1 was significantly produced in the granuloma tissue of untreated animals, an effect increased by LPS and inhibited by dexamethasone, compared with the controls. Moreover, MCP-1 protein was found in the supernatant from homogenized granuloma tissues and the levels of MCP-1 were higher in the LPS-treated animals, while they were lower in the dexamethasone group, compared with the granulomas from the PBS-treated groups (control). The generation of MCP-1 was also found in minced granuloma tissue incubated for 18 hr (overnight) from treated (LPS or dexamethasone) and untreated (PBS) rats. When LPS was added in vitro for 18 hr to the controls and treated animals the production of MCP-1 was further increased except in the dexamethasone group (P > 0.05). Analysing blood serum from LPS, dexamethasone or PBS-treated rats, we found that MCP-1 was also present. The level was higher in the LPS group and lower in the dexamethasone group, compared with the control (PBS). In these studies we show for the first time that MCP-1 transcript and translation is generated in chronic experimental inflammatory tissue, an effect inhibited by dexamethasone.
Subject(s)
Chemokine CCL2/metabolism , Granuloma/immunology , Animals , Chemokine CCL2/genetics , Chemotaxis, Leukocyte/drug effects , Chronic Disease , Culture Techniques , Dexamethasone/pharmacology , Granuloma/chemically induced , Granuloma/pathology , Leukocytes, Mononuclear/immunology , Lipopolysaccharides/pharmacology , Male , Polymerase Chain Reaction , Potassium Permanganate , RNA, Messenger/genetics , Rats , Rats, Wistar , Sodium Chloride/pharmacologyABSTRACT
Mast cells located in connective tissues are a potent source of vasoactive and inflammatory mediators, such as cytokines. They accumulate in tissues in a wide variety of diseases where their function in most cases in unclear. In this report we provide evidence that rat basophilic leukemia cells (RBLC) cultured with a natural inhibitor of IL-1, interleukin-1 receptor antagonist (IL-1RA) (500 ng/ml) for 48 h, strongly inhibited the spontaneous release of serotonin (5HT) (from 25.2 to 29.9%), and histamine (from 22.50 to 43.49%), compared to untreated cells (control). When IL-IRA-treated and -untreated RBLC were stimulated with a secretagogue (anti-IgE), no difference was found in the percent of 5HT and histamine release. The present studies describe an additional biological activity of IL-1RA, inhibiting histamine and 5HT spontaneous release from RBLC cultures.
