monensin and Arthritis--Rheumatoid

Flow cytometry has become a powerful technique to measure intracellular cytokine production in lymphocytes and monocytes. Appropriate inhibition of the secretion of the produced cytokines is required for studying intracellular cytokine expression. The aim of this study was to compare the capacity of cytokine secretion inhibitors, monensin and brefeldin A, in order to trap cytokine production (interleukin-1 beta [IL-1beta], IL-6, tumor necrosis factor-alpha [TNF-alpha]) within peripheral blood monocytes. A two-color flow cytometric technique was used to measure intracellular spontaneous and lipopolysaccharide (LPS)-stimulated IL-1beta, IL-6, and TNF-alpha production in monocytes (CD14+) of whole blood cultures. The viability of monensin-treated monocytes was slightly lower than that of brefeldin A-inhibited monocytes, as measured with propidium iodide (PI). The percentage of IL-6 and TNF-alpha-producing monocytes after 8 h of culture without stimulation revealed significant lower values for monensin-treated than for brefeldin A-treated monocytes. The percentages for stimulated cells did not differ. The spontaneous intracellular production in molecules of equivalent soluble fluorochrome units (MESF) of IL-1beta, IL-6, and TNF-alpha after 8 h of culture was higher in brefeldin A than in monensin-inhibited monocytes. The LPS-stimulated intracellular production of IL-1beta, IL-6, and TNF-alpha was increased in brefeldin A-inhibited monocytes. In conclusion, for flow cytometric determination of intracellular monocytic cytokines (IL-1beta, IL-6, and TNF-alpha), brefeldin A is a more potent, effective, and less toxic inhibitor of cytokine secretion than monensin.

Topics: Adult; Arthritis, Rheumatoid; Brefeldin A; Cell Survival; Cells, Cultured; Female; Flow Cytometry; Humans; Interleukin-1; Interleukin-6; Ionophores; Lipopolysaccharide Receptors; Lipopolysaccharides; Male; Middle Aged; Monensin; Monocytes; Protein Synthesis Inhibitors; Time Factors; Tumor Necrosis Factor-alpha

Matrix metalloproteinases (MMP) are proteolytic enzymes that play a key role in tissue remodelling during physiological and pathological processes, by initiating the degradation of extracellular matrix. MMP overexpression can lead to tissue destruction which is characteristic of chronic inflammatory diseases such as rheumatoid arthritis and scleritis. Plasma cells are often abundant at such sites of chronic inflammation. In the present study we investigated whether plasma cells could contribute to matrix degradation by their expression of MMP In situ hybridization and immunohistochemical analyses on diseased synovial and scleral tissue demonstrated the expression of stromelysin-1 (MMP-3) and gelatinase B (MMP-9), but little or no tissue inhibitor of matrix metalloproteinase 1 (TIMP-1) mRNA, by IgG-positive plasma cells. Northern blot analysis of RNA extracted from a human plasma cell line (ARH-77), Epstein-Barr virus-transformed B cells, and purified peripheral blood B cells, demonstrated expression of stromelysin mRNA. TIMP-1 mRNA was only detected by the more sensitive reverse transcription PCR method in these cell types. Plasma cells and B lymphocytes cultured in the presence of monensin demonstrated cytoplasmic gelatinase B. Gelatin and casein zymography on conditioned media (CM) derived from cytokine treated plasma cells revealed the induction of secreted gelatinase and stromelysin activity. Western blotting confirmed the presence of stromelysin-1 and TIMP-1 proteins in plasma cell CM. These data suggest that plasma cells are not only capable of modulating an inflammatory response by antibody and cytokine production, but also by their ability to produce MMP. Secretion of MMP from focal aggregates of plasma cells may play a critical role in tissue destructive diseases such as rheumatoid synovitis and scleritis.

Topics: Arthritis, Rheumatoid; B-Lymphocytes; Cell Line, Transformed; Collagenases; Humans; Interleukin-1; Matrix Metalloproteinase 3; Matrix Metalloproteinase 9; Monensin; Plasma Cells; RNA, Messenger; Scleritis; Tissue Inhibitor of Metalloproteinase-1; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha

We have detected cytoplasmic anti-Golgi antibody (AGA) during a routine immunofluorescence test for detecting autoantibodies. Two sera from patients with rheumatoid arthritis (RA) reacted to the Golgi complex by an indirect immunofluorescence technique on HEp-2 cells. Localization of AGA in the Golgi complex was confirmed by double-staining with antibodies to beta-COP. The effect of monensin on the integrity and morphology of the Golgi complex was also studied. To confirm the presence of AGA further, we performed immuno-electron microscopy. Both sera reacted with cytoplasmic antigen located in the Golgi complex of various animal tissues. Furthermore, by using the Western blot technique, both sera reacted to a relative molecular weight (MW) of 79 kDa (doublet) Golgi antigen purified from rat liver. To our knowledge, this study may be the first to identify the relative MW of Golgi antigen by the Western blot method. Identification of this antibody could provide better understanding of protein synthesis and secretion. The presence of AGA in RA patients further substantiates the diversified nature of autoantibody production seen in this disease.

Topics: Aged; Arthritis, Rheumatoid; Autoantibodies; Blotting, Western; Female; Golgi Apparatus; Humans; Microscopy, Immunoelectron; Middle Aged; Molecular Weight; Monensin