Nathalie Franchimont

Increased matrix metalloproteinase-3 serum levels in rheumatic diseases: relationship with synovitis and steroid treatment

Objective: To determine matrix metalloproteinase-3 (MMP-3) serum levels in patients with rheumatic diseases and to study the relation between MMP-3 and C reactive protein (CRP) levels. Methods: MMP-3 serum levels were determined by enzyme linked immunosorbent assay (ELISA) in (a) patients with active inflammatory rheumatic diseases: rheumatoid arthritis (RA), psoriatic arthritis, polymyalgia rheumatica, acute crystal arthritis, and ankylosing spondylitis; (b) patients with active inflammatory systemic diseases: cutaneo-articular or renal systemic lupus erythematosus (SLE), systemic sclerosis, and vasculitides; (c) patients with non-inflammatory rheumatic diseases: osteoarthritis and fibromyalgia; (d) critically ill patients without rheumatic diseases, representing an acute inflammatory control group; (e) healthy controls. Results: MMP-3 serum levels were significantly increased in patients with active RA, psoriatic arthritis, and polymyalgia rheumatica, whether treated or not by corticosteroids, and in female patients with acute crystal arthritis. MMP-3 serum levels were normal in steroid-free patients with active cutaneo-articular or renal SLE, systemic sclerosis, and vasculitides but were significantly increased in steroid treated patients. MMP-3 levels were normal in fibromyalgia, osteoarthritis, ankylosing spondylitis, and acute inflammatory controls. MMP-3 was significantly correlated with CRP in RA (r=0.5, p=0.0004) but not in any of the other disease groups. Conclusions: MMP-3 serum levels are increased in inflammatory rheumatic diseases characterised by joint synovitis, such as RA, polymyalgia rheumatica, psoriatic arthritis, and acute crystal arthritis—that is, whether the diseases are acute or chronic, erosive or not. They are normal in SLE, systemic sclerosis, and vasculitides as well as in non-rheumatic inflammatory controls, but are significantly increased by steroids. These data strongly suggest that serum MMP-3 reflects synovial inflammation.

Rapid improvement of bone metabolism after infliximab treatment in Crohn's disease

Background : Crohns disease is associated with low bone mineral density and altered bone metabolism.

Platelet-derived Growth Factor Induces Interleukin-6 Transcription in Osteoblasts through the Activator Protein-1 Complex and Activating Transcription Factor-2

Platelet-derived growth factor (PDGF) BB, a mitogen that stimulates bone resorption, increases the expression of interleukin-6 (IL-6), a cytokine that induces osteoclast recruitment. The mechanisms involved in IL-6 induction by PDGF BB are poorly understood. We examined the effect of PDGF BB on IL-6 expression in cultures of osteoblasts from fetal rat calvariae (Ob cells). PDGF BB increased IL-6 mRNA and heterogeneous nuclear RNA levels, the rate of transcription, and the activity of base pairs (bp) −2906 to +20 IL-6 promoter fragments transiently transfected into Ob cells. Deletion analysis revealed two responsive regions, one containing an activator protein-1 (AP-1) site located between bp −276 and −257, and a second, less well defined, downstream of −257. Targeted mutations of a cyclic AMP-responsive element (CRE), and nuclear factor-IL-6 and nuclear factor-κB binding sites in a bp −257 to +20 IL-6 construct that was transfected into Ob cells, revealed that the CRE also contributed to IL-6 promoter induction by PDGF BB. Electrophoretic mobility shift assay revealed AP-1 and CRE nuclear protein complexes that were enhanced by PDGF BB. Supershift assays revealed binding of Jun and Fos to AP-1 and CRE sequences and binding of activating transcription factor-2 to CRE. In conclusion, PDGF BB induces IL-6 transcription in osteoblasts by regulating nuclear proteins of the AP-1 complex and activating transcription factor-2.

Increased expression of receptor activator of NF-κB ligand (RANKL), its receptor RANK and its decoy receptor osteoprotegerin in the colon of Crohn's disease patients

Crohns disease (CD) is associated with low bone mass due to chronic inflammation and other factors. Receptor activator of NF‐κB ligand (RANKL), its receptor RANK and its decoy receptor osteoprotegerin (OPG) are potentially involved in this process as they regulate osteoclastogenesis and are influenced by pro‐inflammatory cytokines. The aim of this study was to determine the levels of soluble RANKL (sRANKL), RANK and OPG expression both in the serum and in the colon of CD patients. Levels of sRANKL and OPG were assessed in the serum and the supernatants of cultured colonic biopsies in patients with CD and controls by ELISA. RANK expression was explored by immunostaining and immunofluorescence of fixed colonic samples. OPG and sRANKL levels were higher in the serum of CD patients as compared to age‐ and sex‐matched controls. Levels of sRANKL and OPG were significantly enhanced in cultured colonic biopsies from CD, and OPG levels correlated with histological inflammation, and pro‐ and anti‐inflammatory cytokine levels. No significant correlation was found for sRANKL. RANK+ cells were increased in the colon of CD, particularly in inflamed areas. These cells were positive for CD68 or S100 protein. We conclude that serum and local levels of sRANKL and OPG are increased in CD. Moreover, RANK is expressed in the colonic mucosa by subpopulations of activated macrophages or dendritic cells at higher levels in CD compared to normal colon.

Transforming growth factor-β increases interleukin-6 transcripts in osteoblasts

Bone remodeling is regulated by local factors and cytokines. Among them, interleukin-6 (IL-6) plays a critical role in bone resorption, and its synthesis is stimulated by osteoresorptive factors. Transforming growth factor-β (TGF-β) is present in high amounts in the bone matrix and is a local regulator of bone formation. However, its role in bone resorption remains unclear. In this paper, we report that TGF-β stimulates IL-6 transcripts in a time- and dose-dependent manner in primary rat osteoblasts isolated from 22-day-old calvariae (Ob cells). The TGF-β effect on IL-6 mRNA levels does not require de novo protein synthesis because cycloheximide, a protein synthesis inhibitor, does not block the induction. The mechanisms of IL-6 stimulation by TGF-β is at least partially transcriptional because TGF-β induces IL-6 heterogenous nuclear RNA, and, to a lesser extent, IL-6 transcription rate as determined by a nuclear run-on assay. Transforming growth factor-β upregulation of IL-6 may be critical in conditions of increased bone resorption, such as myeloma.

TNF-alpha protects human primary articular chondrocytes from nitric oxide-induced apoptosis via nuclear factor-kappaB

TNF-α plays a key role in rheumatoid arthritis, but its effect on chondrocyte survival is still conflicting. In the present study, we tested how TNF-α influences chondrocyte survival in response to nitric oxide (NO)-related apoptotic signals, which are abundant during rheumatoid arthritis. Human primary articular chondrocytes or cartilage explants were pretreated with TNF-α for 24 hours and then treated with the proapoptotic NO donor sodium-nitro-prusside (SNP) for an additional 24 hours. TNF-α pretreatment markedly protected chondrocytes from SNP-induced cell death. Preincubation of chondrocytes with TNF-α inhibited both SNP-induced high-molecular weight DNA fragmentation and annexin V-FITC binding. Of interest, TNF-α induced persistent nuclear factor-κB (NF-κB)-DNA binding activity even in the presence of SNP, mirroring apoptosis protection effects. Both the TNF-α antiapoptotic effect and NF-κB-DNA binding activity were significantly inhibited by NF-κB inhibitors, Bay 11-7085, MG-132, and adenovirus-expressing mutated IκB-α. Phosphatidylinositol-3 kinase inhibitor LY 294002 also markedly inhibited the antiapoptotic effect of TNF-α. In primary chondrocytes, TNF-α induced expression of the antiapoptotic protein Cox-2, which persisted in the presence of SNP, and a specific Cox-2 inhibitor significantly blocked the TNF-α protective effect. We therefore conclude that TNF-α–mediated protection of chondrocytes from NO-induced apoptosis acts through NF-κB and requires Cox-2 activity.

15-deoxy-delta12,14-prostaglandin J2 inhibits Bay 11-7085-induced sustained extracellular signal-regulated kinase phosphorylation and apoptosis in human articular chondrocytes and synovial fibroblasts

We have previously shown that nuclear factor-κB inhibition by adenovirus expressing mutated IκB-α or by proteasome inhibitor increases human articular chondrocytes sensibility to apoptosis. Moreover, the nuclear factor-κB inhibitor BAY11-7085, a potent anti-inflammatory drug in rat adjuvant arthritis, is itself a proapoptotic agent for chondrocytes. In this work, we show that BAY 11-7085 but not the proteasome inhibitor MG-132 induced a rapid and sustained phosphorylation of extracellular signal-regulated kinases (ERK1/2) in human articular chondrocytes. The level of ERK1/2 phosphorylation correlated with BAY 11-7085 concentration and chondrocyte apoptosis. 15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and its precursor prostaglandin (PG) D2 but not PGE2 and PGF2α rescued chondrocytes from BAY 11-7085-induced apoptosis. 15d-PGJ2 markedly inhibited BAY 11-7085-induced phosphorylation of ERK1/2. BAY 11-7085 also induced ERK1/2 phosphorylation and apoptosis in human synovial fibroblasts, and these reactions were down-regulated by 15d-PGJ2. Further analysis in synovial fibroblasts showed that only molecules that suppressed BAY 11-7085-induced phosphorylation of ERK1/2 (i.e. 15d-PGJ2, PGD2, and to a lesser extent, MEK1/2 inhibitor UO126, but not prostaglandins E2 and F2α or peroxisome proliferator-activated receptor-γ agonist ciglitazone) were able protect cells from apoptosis. These results suggested that the antiapoptotic effect of 15d-PGJ2 on chondrocytes and synovial fibroblasts might involve inhibition of ERK1/2 phosphorylation.

Characterization of the Insulin-Like Growth Factor Axis in the Human Thymus

The components of the insulin‐like growth factor (IGF) axis have been investigated in the normal human thymus. Using ribonuclease protection assays (RPA), IGF‐II transcripts were detected in the normal human thymus. By reverse transcriptase polymerase chain reaction (RT‐PCR) analyses, promoters P3 and P4 were found to be active in the transcription of IGF2 gene within human thymic epithelial cells (TEC). No IGF‐II mRNA could be detected in human lymphoid Jurkat T cells with 30 cycles of RT‐PCR. By Northern blot analyses, IGFBP‐2 to ‐6 (but not IGFBP‐1) were found to be expressed in TEC with a predominance of IGFBP‐4. Interestingly, Jurkat T cells only express IGFBP‐2 but at high levels. The type 1 IGF receptor was detected in Jurkat T cells but not in human TEC. The identification of the components of the IGF axis within separate compartments of the human thymus adds further evidence for a role of this axis in the control of T‐cell development. The precise influence of thymic IGF axis upon T‐cell differentiation and immunological self‐tolerance however needs to be further investigated.

Management of glucocorticoid induced osteoporosis in premenopausal women with autoimmune disease.

Numerous inflammatory rheumatic diseases occurring in premenopausal women require the use of high doses of glucocorticoids (GC). It was believed for many years that premenopausal women were, at least to some extent, protected from bone loss associated with GC therapy. However, epidemiological studies performed in premenopausal women with systemic lupus erythematosus, demonstrate that these patients have lower bone mineral density as compared to age-matched controls. This is explained in part by the underlying disease and in part by treatment with GC. The American College of Rheumatology recommends life style adaptation, supplementation with calcium and vitamin D in patients receiving, or initiating therapy with >/=5 mg equivalent prednisone/day. Bisphosphonates are recommended, but they should be used with caution in young women as they cross the placenta and can affect skeletal remodeling in the foetus. Bisphosphonates have a prolonged terminal half-life and data on their safety extends to 10 years. It is therefore critical to inform premenopausal women about the risks of bisphosphonates and to recommend bisphosphonates with shorter terminal half-life.

Further Insights in the Mechanisms of Interleukin-1β Stimulation of Osteoprotegerin in Osteoblast-Like Cells

The mechanisms of IL‐1β stimulation of OPG were studied in more detail. Whereas p38 and ERK activation was confirmed to be needed, NF‐κB was not necessary for this regulation. We also found that OPG production after IL‐1β stimulation was not sufficient to block TRAIL‐induced apoptosis in MG‐63 cells.