[Frequency of terminally differentiated fibroblasts in the synovial membrane of rheumatoid arthritis patients]

Involvement of IGF binding protein 5 in prostaglandin E(2)-induced cellular senescence in human fibroblasts

Inflammation is an underlying basis for the molecular alterations that link aging and age-related pathological processes. In a previous study, we found that secretory phospholipase A(2) (sPLA(2)) induced cellular senescence in human dermal fibroblasts (HDFs). To further investigate the association of inflammation with cellular senescence, the effects of PGE(2) on cellular senescence in HDFs were investigated, since PGE(2) is the most abundant prostanoid. PGE(2) treatment induces cellular senescence, as determined by a decrease in cell proliferation and an increase in senescence-associated β-galactosidase staining. Notably, PGE(2) treatment increased the IGFBP5 protein level. While treatment with PGE(2) antagonists repressed PGE(2)-induced cellular senescence, increasing intracellular cAMP accelerated cellular senescence. Down-regulation of IGFBP5 inhibited PGE(2)-induced cellular senescence. Taken together, these results suggest that PGE(2) may play an important role in controlling cellular senescence of HDFs through the regulation of IGFBP5 and therefore may contribute to inflammatory disorders associated with aging.

Induction of cellular senescence by secretory phospholipase A2 in human dermal fibroblasts through an ROS-mediated p53 pathway

Secretory phospholipase A(2) (sPLA(2)) is involved in various cellular physiological and pathological responses, especially in inflammatory responses. Accumulating evidence suggests that inflammation is an underlying basis for the molecular alterations that link aging and age-related pathological processes. However, the involvement of sPLA(2) in cellular senescence is not clear. In this study, we found that sPLA(2) treatment induces cellular senescence in human dermal fibroblasts (HDFs), as confirmed by increases in senescence-associated beta-galactosidase activity, changes in cell morphology, and upregulation of p53/p21 protein levels. sPLA(2)-induced senescence was observed in p16-knockdown HDFs and p16-null mouse fibroblasts, but not in p53-knockdown HDFs and p53-null mouse fibroblasts. Treatment with sPLA(2) increases reactive oxygen species (ROS) production, and an antioxidant, N-acetylcysteine, inhibits sPLA(2)-induced cellular senescence. These results suggest that sPLA(2) has a role in cellular senescence in HDFs during inflammatory response by promoting ROS-dependent p53 activation and might therefore contribute to inflammatory disorders associated with aging.

2-Deoxy-2-[F-18]fluoro-D-glucose joint uptake on positron emission tomography images: rheumatoid arthritis versus osteoarthritis

Purpose

Previous positron emission tomography (PET) studies have shown increased 2-deoxy-2-[18F]fluoro-d-glucose (FDG) uptake in joints of patients with osteoarthritis (OA) and inflamed joints of patients with rheumatoid arthritis (RA). This study compares FDG uptake in joints of RA and OA patients and FDG-uptake with clinical signs of inflammation.

Procedures

FDG-PET scans of hands and wrists were performed in patients with RA and primary OA. PET data were compared with clinical data.

Results

29% of RA joints and 6% of OA joints showed elevated FDG-uptake. The level of uptake in PET-positive OA joints was not significantly different from that in RA joints. The majority of PET results of RA joints corresponded with clinical findings. Clinical synovitis was found some OA joints with FDG-uptake.

Conclusions

FDG-uptake was observed in the majority of clinically inflamed RA joints and in a few OA joints with no significant difference in uptake level. The latter may be due to secondary synovitis.