Microsomal prostaglandin E2 synthase 1 expression in basic calcium phosphate crystal-stimulated fibroblasts: role of prostaglandin E2 and the EP4 receptor.

OBJECTIVE: Basic calcium phosphate (BCP) crystals have been implicated in the pathogenesis of osteoarthritis (OA), in part because of their ability to upregulate cyclooxygenase and prostaglandin E(2) (PGE(2)) production. The aim of this work was to investigate the expression of terminal PGE(2) synthases and PGE(2) receptors (EP) in BCP crystal-stimulated fibroblasts. METHODS: Cultured fibroblasts were stimulated with BCP crystals in vitro. mRNA expression was measured by real-time polymerase chain reaction, and protein production by western blotting. RESULTS: Basal expression of microsomal prostaglandin E(2) synthase 1 (mPGES1) in osteoarthritic synovial fibroblasts (OASF) was found to be 30-fold higher than in human foreskin fibroblasts (HFF). BCP crystals increased mPGES1 expression fourfold in HFF, but not in OASF. EP4 expression was downregulated twofold by BCP crystals in OASF, but not in HFF. Exogenous PGE(2) also downregulated EP4 expression; this effect was blocked by co-administration of L-161,982, a selective EP4 antagonist. While administration of exogenous PGE(2) significantly upregulated mPGES1 expression in OASF, mPGES1 expression was threefold higher in the OASF treated with BCP crystals and PGE(2) as compared with OASF treated with PGE(2) alone. CONCLUSIONS: The differing effects of BCP crystals on mPGES1 expression in HFF and OASF may be explained by BCP crystal-induced EP4 downregulation in OASF, likely mediated via PGE(2). These data underline the complexity of the pathways regulating PGE(2) synthesis and suggest the existence of a compensatory mechanism whereby mPGES1 expression can be diminished, potentially reducing the stimulus for further PGE(2) production.

Progressive multifocal leucoencephalopathy in the rheumatic diseases: assessing the risks of biological immunosuppressive therapies.

Progressive multifocal leucoencephalopathy (PML) is a rare and often fatal opportunistic infection that has been well reported in patients with rheumatic diseases. The contributions of predisposing factors such as underlying disease and immunosuppressive drug selection are incompletely understood but it would appear that patients with systemic lupus erythematosus may be at highest risk. Natalizumab, a biological agent approved for multiple sclerosis and Crohn's disease has the clearest pattern of small but definite risk. Although the risk due to rituximab is difficult to assess given the multiple confounders, continued vigilance is warranted. Rheumatologists need to become familiar with PML and feel able to help patients make shared and informed decisions about the risks when starting treatment with immunosuppressive therapies. In particular, rheumatologists need to be vigilant and pursue the diagnosis of PML in all patients with unexplained neurological signs or symptoms with clinical and MRI findings compatible with the diagnosis.

Arteriovenous malformation of the brain mimicking primary central nervous system vasculitis.

In the diagnosis of primary central nervous system (CNS) vasculitis, it is crucial to rule out clinical, angiographic, and pathological mimics. We report a case of arteriovenous malformation (AVM) mimicking primary CNS vasculitis. A young male presented with intracerebral haemorrhage and no other clinical, laboratory, or angiographic features suggesting vasculitis. Cerebral biopsy showed perivascular inflammation and slight infiltration of the muscular layer of cerebral vessels by chronic inflammatory cells close to the haemorrhagic areas. These findings led to a diagnosis of CNS vasculitis. The patient was initially treated with corticosteroids, but 10 months after the discovery and surgical repair of the AVM, the patient is not receiving any immunosuppressant and has not developed any features of cerebral or systemic vasculitis.

Anti-tumour necrosis factor therapy in patients with refractory Takayasu arteritis: long-term follow-up.

OBJECTIVE: To assess the efficacy of anti-tumour necrosis factor (TNF) therapy to induce remission in patients with Takayasu arteritis (TAK) refractory to other immunosuppressive therapies. METHODS: Retrospective single-centre study of 25 patients with refractory TAK. RESULTS: Patients were treated with infliximab (IFX) or etanercept (ETA) for up to 7 years; 21 with IFX (median 28 months (range 2-84)) and 9 with ETA (median 28 months (range 4-82)); 5 patients initially treated with ETA subsequently switched to IFX. Following anti-TNF therapy, remission was achieved and prednisone was discontinued in 15 patients (60%) and successfully tapered below 10 mg/day in an additional 7 patients (28%). Of 18 patients treated with other immunosuppressive agents concurrent with anti-TNF therapy, 9 (50%) could taper or discontinue the additional agent. Major relapses occurred in four patients that initially achieved stable remission. Four patients suffered adverse events, including one with opportunistic infections and one with breast cancer. CONCLUSIONS: In this group of patients with refractory TAK, anti-TNF therapy was associated with remission in a majority of patients, facilitating dose reduction or discontinuation of prednisone and other immunosuppressive therapy. These findings strengthen the rationale for the conducting of a randomised controlled trial of anti-TNF therapy in TAK.

Tumour-like mass lesion: an under-recognised presentation of primary angiitis of the central nervous system.

OBJECTIVE: To describe the occurrence of mass lesions (ML) in primary angiitis of the central nervous system (PACNS) and assess the utility of diagnostic testing and treatment. METHODS: We examined the case records of the Cleveland Clinic (CC), Massachusetts General Hospital (MGH), and the English language medical literature, for biopsy-proven PACNS cases presenting as a solitary ML. Relevant clinical variables were extracted and analysed with JMP software. RESULTS: We identified a total of 38 ML: eight of 202 (4.0%) patients with CC/MGH and 30 of 535 (5.6%) patients with PACNS identified from the medical literature. A higher percentage (13 of 45; 29%) was seen in the amyloid-related angiitis subset. Poorer outcomes were reported in the amyloid group, with five deaths. Of the non-amyloid group, better outcomes were seen in the group treated with corticosteroids and cyclophosphamide as compared with the group treated with corticosteroids alone. CONCLUSIONS: Although rare, PACNS should be considered in the differential diagnosis of ML; greater awareness of this manifestation may facilitate more prompt diagnosis and treatment. Biopsy evidence of angiitis is required for diagnosis; specimens should routinely be stained for amyloid. While excision of the lesion may be curative, aggressive immunosuppressive therapy is associated with favourable outcomes and may obviate the need for surgery.

Mechanism of basic calcium phosphate crystal-stimulated cyclo-oxygenase-1 up-regulation in osteoarthritic synovial fibroblasts.

OBJECTIVES: Basic calcium phosphate (BCP) crystals have been implicated in the pathogenesis of OA and stimulate cyclo-oxygenase (COX) expression and PGE(2) production. This study aimed to elucidate the mechanism of COX-1 up-regulation by BCP crystals and to characterize the PGs produced in OA synovial fibroblasts (OASFs) in response to BCP crystals. METHODS: OASFs were stimulated with BCP crystals in vitro. mRNA expression was measured by real-time PCR, PG production by EIA and protein production by western blot. RESULTS: Maximal (19-fold) up-regulation of COX-1 mRNA occurred 32 h after stimulation with BCP crystals; increased COX-1 protein production was also seen. At 32 h post-stimulation with BCP crystals, PGE(2) (and prostacyclin) production was COX-1 dependent. In contrast, maximal (17-fold) up-regulation of COX-2, with corresponding COX-2-dependent PG production, occurred 4 h after BCP crystal stimulation. There was no appreciable increased production of other PGs such as PGF(2alpha), thromboxane A(2) or cyclopentanone PGs including 15d-PGJ(2). Inhibition of protein kinase C (PKC) and extracellular regulated kinase 1/2 (ERK1/2) signal transduction pathways blocked BCP crystal-induced COX-1 mRNA expression. Bafilomycin A1, an inhibitor of intra-lysosomal BCP crystal dissolution, diminished BCP crystal-induced COX-1 mRNA expression. CONCLUSIONS: These findings indicate that BCP crystals can augment PG production in OASF through induction of COX-1 and COX-2. Intra-lysosomal BCP crystal dissolution and activity of the PKC and ERK1/2 signal transduction pathways are required for BCP crystal-induced COX-1 up-regulation. These data add to the evidence suggesting that the constitutive COX-1/inducible COX-2 concept is an over-simplification and suggest that non-selective COX inhibition may be preferable to COX-2 selective inhibition in BCP crystal-associated OA.

Mechanism of basic calcium phosphate crystal-stimulated matrix metalloproteinase-13 expression by osteoarthritic synovial fibroblasts: inhibition by prostaglandin E2.

OBJECTIVE: To determine the mechanism of matrix metalloproteinase (MMP)-13 upregulation in osteoarthritic synovial fibroblasts (OASF) in response to stimulation with basic calcium phosphate (BCP) crystals and to investigate the effect of prostaglandin (PG)E2 on BCP crystal-stimulated MMP expression. METHODS: Primary OASF were stimulated with BCP crystals; mRNA expression was measured by real-time reverse transcription-polymerase chain reaction and protein levels were assessed by Western blotting. RESULTS: BCP crystals upregulated MMP-13 mRNA expression over 20-fold and increased MMP-13 protein production in OASF. BCP crystal-stimulated MMP-13 mRNA expression was blocked by inhibition of the extracellular regulated kinase (ERK1/2) and p38 mitogen activated protein kinase (MAPK) pathways and inhibition of the activation of nuclear factor kappaB. Addition of exogenous PGE2 downregulated BCP crystal-stimulated MMP-13 expression. In contrast, PGE2 upregulated, and had no effect, on BCP crystal stimulated MMP-3 and MMP-1 mRNA expression, respectively. These effects of PGE2 were diminished by L-161,982, a selective EP4 receptor antagonist, and mimicked by CAY10399, a selective EP2 receptor agonist, and forskolin, an adenylate cyclase activator. CONCLUSIONS: These data suggest that BCP crystal induction of MMP-13 expression may involve the ERK1/2 and p38 MAPK pathways and activation of nuclear factor kappaB; this upregulation of MMP-13 may contribute to the accelerated cartilage breakdown in BCP crystal-associated osteoarthritis. PGE2 had contrasting effects on BCP crystal-stimulated MMP-3 and MMP-13 mRNA expression, mediated in an EP2/EP4/cAMP-dependent manner, suggesting that PGE2 may have beneficial as well as deleterious effects in BCP crystal-associated osteoarthritis.

BCP crystals increase prostacyclin production and upregulate the prostacyclin receptor in OA synovial fibroblasts: potential effects on mPGES1 and MMP-13.

OBJECTIVE: To investigate the potential involvement of prostacyclin in basic calcium phosphate (BCP) crystal-induced responses in osteoarthritic synovial fibroblasts (OASF). METHODS: OASF grown in culture were stimulated with BCP crystals. Prostacyclin production was measured by enzyme immunoassay. Expression of messenger RNA (mRNA) transcripts was assessed by real-time polymerase chain reaction (PCR). Expression of prostacyclin synthase (PGIS) and the prostacyclin (IP) receptor was measured. The effects of iloprost, a prostacyclin analogue, on expression of genes implicated in osteoarthritis such as microsomal prostaglandin E2 synthase 1 (mPGES1) and matrix metalloproteinases (MMPs) were also studied. FPT inhibitor II, a farnesyl transferase inhibitor, was used to antagonize iloprost-induced responses. RESULTS: BCP crystal stimulation led to a five-fold increase in prostacyclin production in OASF compared to untreated cells. This induction was attenuated by cyclooxygenase (COX)-2 and COX-1 inhibition at 4 and 32h, respectively. PGIS and IP receptor transcripts were constitutively expressed in OASF. BCP crystals upregulated IP receptor expression two-fold. While iloprost diminished BCP crystal-stimulated IP receptor upregulation, the inhibitory effect of iloprost was blocked by the farnesyl transferase inhibitor. In addition, iloprost upregulated mPGES1 and downregulated MMP-13 expression in BCP crystal-stimulated OASF, effects that were not influenced by the farnesyl transferase inhibitor. CONCLUSIONS: These data showed for the first time that BCP crystals can increase prostacyclin production and upregulate expression of the IP receptor in OASF. The potential of prostacyclin to influence BCP crystal-stimulated responses was supported by the effects of iloprost on the expression of the IP receptor, mPGES1 and MMP-13. These data demonstrate the potential involvement of prostacyclin in BCP crystal-associated osteoarthritis (OA) and suggest that inhibition of PG synthesis with non-steroidal anti-inflammatory drugs may have both deleterious and beneficial effects in BCP crystal-associated OA.

Calcium crystal deposition diseases: update on pathogenesis and manifestations.

Basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate crystals are the most common types of pathologic calcium-containing crystals. Although these crystals long have been associated with a variety of rheumatic syndromes, recent evidence implicates BCP crystals in the pathogenesis of breast cancer and atherosclerosis. Although understanding of molecular mechanisms involved in generating these pathologic effects has been advanced significantly in recent years, they still are understood incompletely. Such advances are essential to the ongoing search for effective therapies for crystal-associated diseases.

An unusual case of Behçet's syndrome: triggered by typhoid vaccination?

A case of Behçet's syndrome in a 32-year-old woman occurring shortly after her third vaccination against typhoid fever is described. Scleritis and pyoderma gangrenosum were unusual manifestations of BS that occurred in this case. Treatment benefit was provided by mycophenolate mofetil and etanercept. As bacterial antigens have been proposed as potential triggers for the onset of BS, it is possible that the syndrome was precipitated by typhoid vaccination in this patient.

Non-ACTH POMC fragments stimulate aldosterone production by human adrenal cells in vitro.

The possibility that non-ACTH proopiomelanocortin-derived fragments may stimulate aldosterone production has previously been studied using nonhuman cells with inconsistent results. We have examined the response of aldosterone to beta-endorphin (beta-End) and joining peptide (JP) and compared these with the response to ACTH using eight cell suspensions prepared from human adrenal glands. ACTH, 10(-6), 10(-8), and 10(-10) M, consistently stimulated aldosterone accumulation above that occurring in unstimulated cells (150 +/- 83, 120 +/- 62, and 77 +/- 32 fmol/10(4) cells above basal, respectively; mean +/- SE; p < 0.05). beta-End significantly stimulated aldosterone production at 10(-6) and 10(-8) M (114 +/- 84 and 50 +/- 24 fmol/10(4) cells above basal; p < 0.05); 10(-10) M beta-End did not provide significant stimulation. Furthermore, JP stimulated aldosterone biosynthesis (41 +/- 16 fmol/10(4) cells above basal; p < 0.05), only at the highest concentration used, 10(-6) M. The addition of 10(-8) M ACTH plus 10(-6) and 10(-10) M beta-End to human adrenal cells yielded values significantly greater than those achieved with either agent alone (267 +/- 152 and 183 +/- 89 fmol/10(4) cells above basal; p < 0.05). These data indicate for the first time that beta-End and JP have the capacity to stimulate aldosterone production in human adrenal cells in vitro. The physiological and potential clinical significance of these observations has yet to be elucidated.