The aim of this study was to investigate the expression and localization of cyclooxygenase-1 and -2 (COX-1 and COX-2) in synovial tissues from patients with rheumatoid arthritis (RA). Synovial tissues from 9 patients with RA and 5 patients with osteoarthritis (OA) were examined for COX-1 and COX-2 expressions by immunohistochemical staining using 2 polydonal COX-1 and COX-2 antibodies. In RA synovia, synovial lining cells showed intense immunostaining for COX-1, whereas slight to moderate staining was observed in inflammatory cells, stromal fibroblast-like cells and vascular endothelial cells. There was no significant difference in COX-1 expression between RA and OA synovia. The localization of COX-2 expression dearly differed from that of COX-1 expression, being most intense in inflammatory cells. However, there was no difference in COX-1 and COX-2 expressions between RA and OA synovial tissues. Our observations support that inflammatory mechanisms modulated by COX-1 and COX-2 in chronic RA synovium might be similar to those in chronic OA synovium.
Adult ; Aged ; Arthritis, Rheumatoid/pathology ; Arthritis, Rheumatoid/enzymology* ; Cell Division ; Female ; Fibrin/metabolism ; Human ; Isoenzymes/metabolism ; Isoenzymes/biosynthesis* ; Male ; Middle Age ; Neutrophil Infiltration ; Osteoarthritis/enzymology ; Prostaglandin-Endoperoxide Synthase/metabolism ; Prostaglandin-Endoperoxide Synthase/biosynthesis* ; Stromal Cells/pathology ; Stromal Cells/enzymology ; Synovial Membrane/pathology ; Synovial Membrane/enzymology*

Cyclooxygenase (COX) is a key enzyme in the conversion of arachidonic acid into prostanoids which participate in various cellular functions including apoptosis, mitogenesis, inflammation, immune modulation and differentiation. Moreover, the synthetic glucocorticoid, dexamethasone has immune modulating and anti-inflammatory effects in vivo. Recently, dexamethasone was found to enhance retinoic acid-induced neuronal differentiation. In this study, we investigated the mechanisms of dexamethasone-mediated neuronal differentiation. Immunoblotting and morphological analysis demonstrated that dexamethasone induced neuronal differentiation through COX 1 induction. This phenomenon was inhibited by indomethacin, a COX inhibitor. In addition, the addition of exogenous prostaglandin E2 (PGE2), a substance produced by the COX-mediated pathway, triggered neurite outgrowth of cells treated with COX inhibitor. Taken together, COX 1 appears to play an important role in dexamethasone-mediated neuronal differentiation.
Animals ; Anti-Inflammatory Agents/pharmacology ; Cell Differentiation/*drug effects ; Cyclooxygenase Inhibitors/pharmacology ; Dexamethasone/*pharmacology ; Dinoprostone/metabolism ; Enzyme Induction ; Hybrid Cells ; Indomethacin/pharmacology ; Isoenzymes/*biosynthesis ; Mice ; Prostaglandin-Endoperoxide Synthase/*biosynthesis ; Rats ; Tumor Cells, Cultured

OBJECTIVETo investigate the expression of two inflammation related enzymes - cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) during the experimental rat lung carcinogenesis.

METHODSEighty Wistar rats were instilled with 3-methylcholanthrene (MCA) and diethylinitrosamine (DEN) into the left lobar branchus to induce lung squamous cell carcinoma. To obtain specimen in every pathological phase during the carcinogenesis, these rats were sacrificed at different intervals. The expression of COX-2 and iNOS in every pathological phase during the carcinogenesis were examined by immunohistochemical method. The immunohistochemical scores (IHS) were calculated by combining an estimate of the percentage of immunoreactive cells with that of the stain intensity.

RESULTS155 specimens of every pathological phase during the carcinogenesis showed: hyperplasia 14, squamous metaplasia 25, dysplasia 33, carcinoma in situ 12, infiltrating carcinoma 54 and metastasis 17. Inflammation and elevated expressions of COX-2 and iNOS were shown in the precancerous lesions. The COX-2 IHS was significantly increased in dysplasia, carcinoma in situ and metastasis (P < 0.01, P < 0.05, P < 0.01 respectively). The iNOS IHS significantly increased in hyperplasia and metastasis (P < 0.05, P < 0.01 respectively). There was a positive correlation between the expression of COX-2 and iNOS (gamma = 0.601 6, P < 0.001).

CONCLUSIONCOX-2 and iNOS, two inflammation related enzymes, playing important roles in the carcinogenesis of MCA and DEN, induce rat lung squamous cell carcinoma as well as its metastasis. The relation between inflammation and carcinogenesis may partly be explained by the elevated expression of these two enzymes. Nonsteroidal antiinflammatory drug (COX-2 inhibitors) and iNOS inhibitors may possess antitumor activities because of their prevention of bronchial dysplasia, carcinogenesis and metastasis.

Animals ; Carcinogens ; adverse effects ; Carcinoma, Squamous Cell ; chemically induced ; enzymology ; pathology ; Cyclooxygenase 2 ; Female ; Immunohistochemistry ; methods ; Isoenzymes ; biosynthesis ; Lung Neoplasms ; chemically induced ; enzymology ; pathology ; Male ; Methylcholanthrene ; adverse effects ; Neoplasms, Experimental ; chemically induced ; enzymology ; pathology ; Nitric Oxide Synthase ; biosynthesis ; Nitric Oxide Synthase Type II ; Prostaglandin-Endoperoxide Synthases ; biosynthesis ; Rats ; Rats, Wistar

IL-1beta is known promote cyclooxygenase-2 (COX- 2) and matrix metalloproteinase-2 (MMP-2) expression. This study focuses on the characterization of the signaling cascade associated with IL-1beta-induced matrix metalloproteinase-2 (MMP- 2) regulation in human chondrocytes. The decrease in collagen levels in the conditioned media was prevented by a broad spectrum MMP inhibitor, suggesting that IL-1beta promotes the proteolytic process leading to MMP-2 activation. IL-1beta-related MMP-2 expression was found to be dependent on prostaglandin E2 (PGE2) production. In addition, the induction of COX-2 and MMP-2 was inhibited by the pretreatment of chondrocytes with a SB203580 or Ro 31-8220, indicating the involvement of protein kinase C (PKC) or p38 mitogen-activated protein kinase (MAPK). However, there is no cross-talk between PKC and p38 MAPK in the IL-1beta-induced MMP-2 activation. Taken together, these results demonstrated that IL-1beta induces MMP-2 expression through the PGE2-dependent mechanism in human chondrocytes.
Chondrocytes/drug effects/*enzymology/metabolism ; Dinoprostone/analysis/*metabolism ; Gelatinase A/analysis/*biosynthesis ; Humans ; Indoles/pharmacology ; Interleukin-1/*pharmacology ; Isoenzymes/antagonists & inhibitors/metabolism ; Nitrobenzenes/pharmacology ; Phosphorylation/drug effects ; Prostaglandin-Endoperoxide Synthase/metabolism ; Protein Kinase C/antagonists & inhibitors/metabolism ; Research Support, Non-U.S. Gov't ; Sulfonamides/pharmacology ; Up-Regulation ; p38 Mitogen-Activated Protein Kinases/metabolism