romurtide and Arthritis

To examine the involvement of cytokines in the mechanisms of N2-[(N-acetylmuramoyl)-L-alanyl-D-isoglutaminyl]-N6-stearoyl-L-lysine, MDP-Lys(L18)-induced arthritis, we analyzed interleukin-1 (IL-1), tumor necrosis factor (TNF), colony-stimulating factor (CSF), and neutrophil chemotactic factor (NCF) by bioassays in the rat macrophage-conditioned medium (Mluminal diameter-CM) stimulated by MDP-Lys(L18) in vitro and the synovial fluid from dogs treated subcutaneously with MDP-Lys(L18) for 14 days in vivo. The dog showed arthritis characterized by swelling of the knee joint, increased synovial fluid and thickened synovial membrane, and a single subcutaneous injection of MDP-Lys(L18) was previously shown to induced synovitis in rat tarsal joint. IL-1, TNF, CSF, and NCF activities in Mluminal diameter-CM were increased by MDP-Lys(L18), while only NCF activity was detected in the dog synovial fluid. Partial purification procedures revealed that NCF in Mluminal diameter-CM was not leukotriene B4 but a protein having heparin-affinity, and, in addition, immuno-reactive IL-8 was evident to be in Mluminal diameter-CM. The NCF activity in the dog synovial fluid was not inhibited by dialysis, showing that NCF is a protein substance, possibly a chemokine. These results suggest that MDP-Lys(L18) produces a chemokine, such as IL-8, which recruits neutrophils to the synovial membrane for subsequent development of synovitis in rats and dogs.

Topics: Acetylmuramyl-Alanyl-Isoglutamine; Animals; Arthritis; Benzoquinones; Cells, Cultured; Chemotaxis, Leukocyte; Colony-Stimulating Factors; Culture Media, Conditioned; Cycloheximide; Cytokines; Dogs; Gene Expression Regulation; Interleukin-1; Interleukin-8; Lipoxygenase Inhibitors; Macrophages, Peritoneal; Male; Neutrophils; Protein Synthesis Inhibitors; Rats; Rats, Sprague-Dawley; Stimulation, Chemical; Synovial Fluid; Tumor Necrosis Factor-alpha

Muramyl dipeptide-Lys(L18) given by daily subcutaneous injection for 14 days induced arthritis in male Lewis, Fischer and nude rats, to a lesser degree in the last two than in the first strain. On the other hand, a single intradermal administration of Freund's complete adjuvant induced arthritis in Lewis and Fischer but not nude rats. Cyclosporin A (CsA) co-administered for 14 days markedly exacerbated the muramyl dipeptide-Lys(L18) induced arthritis (MIA) in rats of all three strains, but completely blocked the development of the adjuvant induced arthritis (AIA) in Lewis rats. Furthermore, AIA was transferred to recipient Lewis rats through spleen cells obtained from the donors with AIA, whereas MIA was not. Antibodies against type II collagen and DNA were not detected in sera from MIA or AIA rats. These data show a clear difference between MIA and AIA in the pattern of development of arthritis and suggest that delayed hypersensitivity reactions may be involved in the pathogenetic mechanisms of AIA, but not in MIA.

Topics: Acetylmuramyl-Alanyl-Isoglutamine; Adjuvants, Immunologic; Animals; Arthritis; Arthritis, Experimental; Autoantibodies; Cyclosporine; Drug Interactions; Immunoglobulin G; Male; Rats; Rats, Inbred F344; Rats, Inbred Lew; Rats, Nude; Species Specificity; Spleen

We examined changes of blood cell counts and development of arthritis induced by daily subcutaneous injections of MDP-Lys(L18), an analogue of muramyl dipeptide (MDP), in rats. The numbers of neutrophils markedly increased in the peripheral blood 4 hr after the 1st, 7th, and 14th administrations of MDP-Lys(L18), but they recovered to the control levels within 24 hr. Monocyte and lymphocyte counts increased after the 7th and 14th administrations, respectively, although both decreased after the 1st dosing. Serum inflammatory markers, such as albumin, globulin, mucoprotein, sialic acid, and iron, showed marked changes after the 1st administration. Histopathologically, the synovial membrane of the tarsal joint showed a multilayer arrangement of synoviocytes with vesicular cytoplasms and infiltration of neutrophils from 6 hr after the 1st administration of the drug. The acute synovitis was gradually enhanced until 24 hr later. The synovitis was greatly decreased in degree after the 3rd administration, but increased again later. After the 7th and 14th administrations, mononuclear cells and lymphocytes, respectively, infiltrated the synovial membrane, in a manner corresponding to the hematological findings. However, exudative changes and neutrophilic infiltration were still observed after the 14th drug administration, and the synovitis was repaired after a 7-day recovery period.

Topics: Acetylmuramyl-Alanyl-Isoglutamine; Animals; Arthritis; Body Weight; Bone Marrow; Bone Marrow Cells; Female; Leukocyte Count; Male; Rats; Rats, Inbred Strains; Sex Factors; Synovial Membrane; Tarsal Joints; Time Factors