adrenomedullin and Arthritis--Rheumatoid

To determine the effects of adrenomedullin (AM) on interleukin (IL)-1β-induced proliferation of rheumatoid synovial fibroblasts (RASFs) and production of matrix metalloproteinases (MMPs), cyclooxygenase (COX) and prostaglandin E2 (PGE2) by RASFs. The RASFs proliferation was evaluated with CCK-8 reagent in the presence of IL-1β with/without AM (1-52) and AM inhibitor (AM (22-52)). MMPs, tissue inhibitor of metalloproteinase (TIMP-1), COXs, PGE2 and intracellular mitogen-activated protein kinase (MAPK) signalings, including p-ERK, p-p38, p-JNK were examined by immunoblotting or semiquantitative RT-PCR and ELISA. AM (1-52) inhibited IL-1β-induced RASFs proliferation and inhibited MMP-1, 3, COX-2 and PGE2 production. AM (1-52) also inhibited IL-1β-induced phosphorylation of ERK-1/2, p38, JNK. AM 22-52 inhibited the effects of AM (1-52) on proliferation of RASFs and production of MMP-1, 3, COX-2 via MAPKs. These results suggest that AM might involved joint destruction in rheumatoid arthritis and indicate that it might be a new therapeutic modality for management of this disease.

Topics: Adrenomedullin; Arthritis, Rheumatoid; Cell Proliferation; Cells, Cultured; Cyclooxygenase 2; Dinoprostone; Fibroblasts; Gene Expression; Humans; Interleukin-1beta; MAP Kinase Signaling System; Matrix Metalloproteinases; RNA, Messenger; Synovial Membrane; Tissue Inhibitor of Metalloproteinase-1

The aim of this study was to investigate plasma adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) level in patients diagnosed with early rheumatoid arthritis (RA). Furthermore, several inflammatory cytokines were measured in those patients to clarify the roles of AM and PAMP. Forty patients diagnosed with early RA (women 46 +/- 8.5 years old) and 10 healthy controls (women 57 +/- 5 years old) were studied. Plasma levels of AM, PAMP, matrix metalloprotease 3 (MMP-3), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and C-reactive protein (CRP) were measured using an immunoradiometric assay and enzyme-linked immunosorbent asay (ELISA) methods. The plasma levels of AM (17.5 +/- 8.4 fmol/ml) and PAMP (2.01 +/- 0.57 fmol/ml) in patients exceeded those in healthy controls (AM 8.6 +/- 1.7, PAMP 1.17 +/- 0.34 fmol/ml). Moreover, plasma AM and PAMP levels demonstrated a significantly positive correlation with plasma MMP-3 and IL-6 levels. Nevertheless, CRP and TNF-alpha levels in these patients showed no significant correlation with plasma AM and PAMP levels. These data support the possible role for AM and PAMP in the pathophysiology of early RA.

Topics: Adrenomedullin; Adult; Arthritis, Rheumatoid; C-Reactive Protein; Early Diagnosis; Female; Humans; Interleukin-6; Matrix Metalloproteinase 3; Middle Aged; Tumor Necrosis Factor-alpha

The objective of this study is to determine the effects of adrenomedullin (AM) on IL-1- and TNF-alpha-induced rheumatoid synovial fibroblasts (RASFs)-mediated osteoclastogenesis. The formation of osteoclasts in co-cultures of RASFs and peripheral blood mononuclear cells was evaluated by tartrate-resistant acid phosphatase and resorption pit formation assay. The expression of RANKL, OPG, p-ERK, p-p38, and p-JNK was examined by immunoblotting and quantitative reverse transcription-polymerase chain reaction. AM (1-52) inhibits IL-1- and TNF-alpha-induced RASFs-mediated osteoclastogenesis. AM affected IL-1-, TNF-alpha-induced RANKL and OPG expression in RASFs. AM also inhibits IL-1 and TNF-alpha-induced phosphorylation of ERK-1/2, p38 MAPK, and JNK. Inhibitor of AM (AM 22-52) inhibits the effects of AM on the osteoclastogenesis. These results suggest that AM might be involved in the inflammatory cytokines-mediated osteoclastogenesis and thus bone damage, and indicate that it can be a new therapeutic strategy against joint destruction in RA.

Topics: Acid Phosphatase; Adrenomedullin; Arthritis, Rheumatoid; Coculture Techniques; Fibroblasts; Humans; Interleukin-1; Isoenzymes; Leukocytes, Mononuclear; Mitogen-Activated Protein Kinases; Osteoclasts; Osteoprotegerin; RANK Ligand; Recombinant Proteins; RNA, Messenger; Synovial Membrane; Tartrate-Resistant Acid Phosphatase; Time Factors; Tumor Necrosis Factor-alpha

Rheumatoid arthritis (RA) is characterized by fibroblast-like synoviocyte (FLS) hyperplasia, which is partly ascribable to decreased apoptosis. In this study, we show that adrenomedullin (ADM), an antiapoptotic peptide, is constitutively secreted in larger amounts by FLS from joints with RA (RA-FLS) than with osteoarthritis (OA-FLS). ADM secretion was regulated by TNF-alpha. Peptidylglycine alpha-amidating monooxygenase, the ADM-processing enzyme, was expressed at the mRNA level by both RA-FLS and OA-FLS. Constituents of the ADM heterodimeric receptor calcitonin receptor-like receptor (CRLR)/receptor activity-modifying protein (RAMP)-2 were up-regulated at the mRNA and protein levels in cultured RA-FLS compared with OA-FLS. ADM induced rapid intracellular cAMP production in FLS and reduced caspase-3 activity, DNA fragmentation, and chromatin condensation in RA-FLS exposed to apoptotic conditions, indicating that CRLR/RAMP-2 was fully functional. ADM-induced cAMP production was less marked in OA-FLS than in RA-FLS, suggesting differences in receptor regulation and expression. ADM dose-dependently inhibited RA-FLS apoptosis, and this effect was reversed by the 22-52 ADM antagonist peptide. ADM inhibited RA-FLS apoptosis triggered by extrinsic and intrinsic pathways. Our data suggest that ADM may prevent or reduce RA-FLS apoptosis, via up-regulation of its functional receptor CRLR/RAMP-2. Regulation of ADM secretion and/or CRLR/RAMP-2 activation may constitute new treatment strategies for RA.

Topics: Adenylyl Cyclases; Adrenomedullin; Apoptosis; Arthritis, Rheumatoid; Calcitonin Receptor-Like Protein; Cell Separation; Cells, Cultured; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Fibroblasts; Gene Expression Regulation; Humans; Intracellular Signaling Peptides and Proteins; Membrane Proteins; Peptide Fragments; Peptides; Receptor Activity-Modifying Proteins; Receptors, Adrenomedullin; Receptors, Calcitonin; Receptors, Peptide; Signal Transduction; Synovial Membrane; Tumor Necrosis Factor-alpha

It was recently reported that plasma levels of adrenomedullin (AM), identified as a vasorelaxant peptide, are significantly higher in rheumatoid arthritis (RA) patients than in osteoarthritis (OA) patients. The objective of the present study was to elucidate AM production in synovial cells from patients with RA. Adrenomedullin mRNA was detected in cultured synovial cells from RA patients by reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemical analysis demonstrated the presence of AM in synovial cells from RA patients. In addition, we investigated AM levels in knee joint fluids from RA and OA patients. Those from RA patients were elevated approximately threefold over those of OA patients. In this study, we demonstrated for the first time AM expression in synovial cells from RA patients and high levels of AM production in RA joint fluid.

Topics: Adrenomedullin; Aged; Aged, 80 and over; Arthritis, Rheumatoid; Cells, Cultured; Humans; Knee Joint; Peptides; RNA, Messenger; Synovial Membrane; Up-Regulation

Topics: Adrenomedullin; Arthritis, Rheumatoid; Cells, Cultured; Depression, Chemical; Dose-Response Relationship, Drug; Endothelin-1; Humans; Immunohistochemistry; Interleukin-6; Osteoarthritis; Peptides; Synovial Fluid; Synovial Membrane

Peripheral T lymphocytes undergo activation by antigenic stimulation and function in hypoxic areas of inflammation. We demonstrated in CD3-positive human T cells accumulating in inflammatory tissue expression of the hypoxia-inducible factor-1alpha (HIF-1alpha), indicating a role of hypoxia-mediated signals in regulation of T cell function. Surprisingly, accumulation of HIF-1alpha in human T cells required not only hypoxia but also TCR/CD3-mediated activation. Moreover, hypoxia repressed activation-induced cell death (AICD) by TCR/CD3 stimulation, resulting in an increased survival of the cells. Microarray analysis suggested the involvement of HIF-1 target gene product adrenomedullin (AM) in this process. Indeed, AM receptor antagonist abrogated hypoxia-mediated repression of AICD. Moreover, synthetic AM peptides repressed AICD even in normoxia. Taken together, we propose that hypoxia is a critical determinant of survival of the activated T cells via the HIF-1alpha-AM cascade, defining a previously unknown mode of regulation of peripheral immunity.

Topics: Adrenomedullin; Arthritis, Rheumatoid; Autocrine Communication; Cell Death; Cell Hypoxia; Cell Survival; Cells, Cultured; DNA-Binding Proteins; Down-Regulation; Gene Expression Profiling; Humans; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Jurkat Cells; Lymphocyte Activation; Nuclear Proteins; Oligonucleotide Array Sequence Analysis; Peptides; Receptor-CD3 Complex, Antigen, T-Cell; Synovial Membrane; T-Lymphocyte Subsets; Transcription Factors

To elucidate the pathophysiological role of adrenomedullin (AM) in rheumatoid arthritis (RA), plasma AM concentration was measured in patients with RA and in healthy contols. The concentration of AM in joint fluid, synovial tissue, and articular cartilage of patients with RA and osteoarthritis (OA) were measured and compared.. Twenty-six patients with RA (aged 62 +/- 4 yrs, all female), 10 healthy controls (aged 57 +/- 5 yrs, all female), and 10 patients with OA (aged 68 +/- 8 yrs, all female) were studied. We measured plasma levels of total and mature AM by immunoradiometric assay and levels of AM in joint tissue by radioimmunoassay.. Plasma levels of AM in patients with RA (18.35 +/- 6.9 fmol/ml) were found to exceed those in healthy controls (11.64 +/- 2.8 fmol/ml). Moreover, plasma AM showed a significant positive correlation with plasma C-reactive protein (CRP). The correlation coefficient of total AM was 0.685, and that of mature AM was 0.624. Similarly, AM levels in synovium and joint fluid in patients with RA were significantly higher than in OA. In contrast, AM levels in articular cartilage were found to be low, with no significant difference in levels between patients with RA and OA.. The relation between plasma AM levels and plasma CRP in patients with RA suggests that plasma AM levels increase with the activity of RA. Moreover, AM levels in synovium and joint fluid of patients with RA were significantly higher than those of patients with OA. Thus, AM probably plays a part in the regulation of the inflammatory process of RA.

Topics: Adrenomedullin; Aged; Arthritis, Rheumatoid; Cartilage, Articular; Female; Humans; Joints; Middle Aged; Osteoarthritis, Knee; Peptides; Radioimmunoassay; Synovial Membrane

Topics: Adrenomedullin; Arthritis, Rheumatoid; Biomarkers; Blood Sedimentation; Humans; Middle Aged; Peptides; Rheumatic Diseases