Activation of the transcription factor nuclear factor‐κB in human inflamed synovial tissue

Objective. To determine the signal transduction pathways in CD14؉ synovial cells from patients with rheumatoid arthritis (RA) after CD40 ligation, and to examine their role in amplifying synovial inflammation in affected joints.Methods. Expression of messenger RNA was analyzed using quantitative reverse transcriptionpolymerase chain reaction. Cytokines and chemokines were measured using enzyme-linked immunosorbent assay. Activation of kinases was detected using Western blotting. Nuclear translocation of NF-B was examined using immunohistochemistry. CD14؉ synovial cells were enriched using magnetic cell sorting. Fibroblastlike synoviocytes (FLS) were obtained by passaging primary synovial cell culture.Results. Stimulation of CD14؉ synovial cells from RA patients by recombinant soluble CD154 (rsCD154) significantly induced expression of tumor necrosis factor ␣ (TNF␣),

Section: Discussionmentioning

confidence: 99%

Amplification of the synovial inflammatory response through activation of mitogen‐activated protein kinases and nuclear factor κB using ligation of CD40 on CD14+ synovial cells from patients with rheumatoid arthritis

Harigai¹,

Hara²,

Kawamoto³

et al. 2004

“…Cell stimulation induces degradation of I B, resulting in nuclear translocation of the Rel/NF-B subunits and activation of transcription. Activated Rel/NF-B subunits are abundantly expressed in RA synovial tissue and in experimental models of arthritis (5)(6)(7)(8)(9). In studies involving experimental arthritis, there is evidence to suggest that the Rel/NF-B subunits play distinct roles in the pathogenesis of inflammatory arthritis (10).…”

mentioning

confidence: 99%

Increased synovial tissue NF‐κB1 expression at sites adjacent to the cartilage–pannus junction in rheumatoid arthritis

Benito

Murphy

et al. 2004

Objective. To compare the expression of the Rel/ NF-B subunits, NF-B1 (p50) and RelA (p65), in paired synovial tissue samples selected from sites adjacent to and remote from the cartilage-pannus junction (CPJ) in patients with inflammatory arthritis.Methods. Synovial tissue was selected at arthroscopy from sites adjacent to the CPJ and from the suprapatellar pouch of patients who were referred to an early arthritis clinic. Tissue samples from patients with osteoarthritis (OA) undergoing knee arthroplasty were also studied. Rel/NF-B subunit activation and expression were measured by electrophoretic mobility shift assay and supershift analyses and by immunohistochemistry.Results. Tissue samples were obtained from 10 patients with rheumatoid arthritis (RA), 7 with a seronegative arthropathy (SnA), and 6 with OA. Rel/NF-B was abundantly expressed in all samples. In both RA and SnA synovial tissue, the absolute number of NF-B1؉ cells at the CPJ was significantly higher than at non-CPJ sites (P ‫؍‬ 0.006 and P ‫؍‬ 0.02, respectively). The proportion of cells expressing NF-B1 was also significantly higher at the CPJ compared with non-CPJ sites (P ‫؍‬ 0.003 in RA, P ‫؍‬ 0.009 in SnA). The numbers of RelA؉ cells were consistently lower throughout. In RA synovial tissue, but not in SnA synovial tissue, both the absolute number and the proportion of RelA؉ cells were significantly higher at the CPJ than at non-CPJ sites (P ‫؍‬ 0.003 and P ‫؍‬ 0.01, respectively). In OA synovial tissue, the numbers of cells expressing NF-B1 and RelA were similar to those observed at the non-CPJ sites in all inflammatory tissues studied.Conclusion. In this study of early inflammatory arthritis, expression of NF-B1 in synovial tissue was highest at sites most likely to be associated with joint erosion. These observations are consistent with a critical role of NF-B1 in joint destruction, and support the rationale for specific therapeutic inhibition of NF-B in RA.

“…NF-B has been detected by immunohistology in human synovial tissue from RA patients during both early and later stages of disease and in both macrophage-and fibroblast-like synoviocytes (15,16). In particular, macrophage-like synoviocytes that localize in the synovial lining layer and the vascular endothelium have been shown to contain p65 and p50 NF-B subunits in their nucleus (16).…”

mentioning

confidence: 99%

“…In particular, macrophage-like synoviocytes that localize in the synovial lining layer and the vascular endothelium have been shown to contain p65 and p50 NF-B subunits in their nucleus (16). This NF-B activation is of functional relevance, since we recently showed that it regulates the expression of TNF␣ as well as other proinflammatory cytokines, such as IL-1␤, IL-6, IL-8, MMP-1 (collagenase 1) and MMP-3 (stromelysin 1), without major effects on the expression of antiinflammatory cytokines IL-10, IL-11, and IL-1 receptor antagonist, soluble TNF receptors, or tissue inhibitor of metalloproteinases 1 (17) in ex vivo synovial membrane cultures.…”

mentioning

confidence: 99%

Heterogeneous requirement of IκB kinase 2 for inflammatory cytokine and matrix metalloproteinase production in rheumatoid arthritis: Implications for therapy

Andreakos¹,

Smith²,

Kiriakidis³

et al. 2003

Objective. To investigate the potential role of I B kinase 1 (IKK-1) and IKK-2 in the regulation of nuclear factor B (NF-B) activation and the expression of tumor necrosis factor ␣ (TNF␣), as well as interleukin-1␤ (IL-1␤), IL-6, IL-8, vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMPs), in rheumatoid arthritis (RA).Methods. Recombinant adenoviruses expressing ␤-galactosidase, dominant-negative IKK-1 and IKK-2, or I B␣ were used to infect ex vivo RA synovial membrane cultures and synovial fibroblasts obtained from patients with RA undergoing joint replacement surgery, or human dermal fibroblasts, human umbilical vein endothelialcells(HUVECs),andmonocyte-derivedmacrophages from healthy volunteers. Then, their effect on the spontaneous or stimulus-induced release of inflammatory cytokines, VEGF, and MMPs from RA synovial membrane cells was examined.Results. IKK-2 was not required for lipopolysaccharide (LPS)-induced NF-B activation or TNF␣, IL-6, or IL-8 production in macrophages, but was essential for this process in response to CD40 ligand,