Apoptosis resistance in pigmented villonodular synovitis

Objective: Pigmented villonodular synovitis (PVNS) is a proliferative lesion originating from synovial tissue with a locally aggressive behaviour. We analysed the pathogenetic role of apoptosis resistance for sustained cell proliferation in PVNS. Methods: The expression of bcl-2, p53 and Ki-67 was examined in 80 cases of PVNS using immunohistochemistry. In 43 of these cases, DNA content and distribution of cell-cycle phases were investigated by flow cytometry. Additionally, 10 cases of PVNS were analysed by multiparametric flow cytometry for expression of p53, caspase3, and bcl-2 and by TUNEL to detect DNA fragmentation. Results: No apoptotic cell fractions were detected in any investigated cases. Expression of bcl-2 was found in 84% of cases (up to 6.5% of cells) and was significantly associated with DNA-fragmentation observed by TUNEL (p=0.037). Orthologous p53 expression was observed in 37% of cases. The level of p53 expression correlated with the proliferative activity and the expression of both caspase3 (p=0.017) and bcl-2 (p=0.0013). (No statistically significant correlations between expression of bcl-2, p53, caspase3, DNA fragmentation or proliferative index and age, sex of patients, disease recurrence, growth pattern or size of lesion were found). Conclusion: Apoptosis resistance is a critical event in the progression of PVNS and may contribute to the survival of the proliferating synovial cells in PVNS and to the permanent slow progression of these lesions

Comparative analysis of cell populations involved in the proliferative and inflammatory processes in diffuse and localised pigmented villonodular synovitis

The aim of the present study was a comparative quantitative evaluation of cell populations involved in the proliferative and inflammatory compartment in both localised and diffuse pigmented synovitis villonodularis (PVNS). 15 cases of each localised and diffuse PVNS were examined by flow cytometry, immunohistochemistry, double immunofluorescence and confocal microscopy with quantitative evaluation of CD3-, CD4-, CD8-, CD20-, CD57-, CD55-, CD68-, CD163- and h4Ph positive (+) cells. The proliferative compartment of localised and diffuse PVNS was mainly composed of double-positive CD68+/h4Ph+ (CD163+/CD55+) synoviocytes. The number of doublepositive synoviocytes for macrophage and fibroblast markers was significantly higher in diffuse compared to localised PVNS. The accompanying inflammatory infiltrate showed a predominance of cytotoxic cells (CD8+, CD57+), whereby the number of CD3+ and CD20+ cells was significantly higher in localised PVNS. The number of CD57+ NK cells was significantly higher in diffuse PVNS. The proliferating macrophage- like synovial cells and the cytotoxic lymphocytes could contribute to the aggressive behaviour of localised and diffuse PVNS. Moreover, with regard to the quantitative differences in cell composition between diffuse and localised PVNS and their different clinical behaviour, further studies should continue to analyse localised and diffuse PVNS separately

Expression pattern of cell cycle-related gene products in synovial stroma and synovial lining in active and quiescent stages of rheumatoid arthritis

Objective: To investigate the expression pattern of cell cycle related gene products in active and quiescent Rheumatoid arthritis (RA). Methods: Synovial tissue from 20 patients with active proliferative RA and 28 patients with RA in remission was immunohistochemically examined for expression of p53, p63, p21, p27, p16, cyclin D1, CDK4, RB, E2F, Ki-67 on tissue microarrays and by DNA flow cytometry for cell cycle phases. Results: Elevated expression of p53 and p27 was found in synovial lining and in stromal cells in proliferative active RA. In the remission stage this finding was confined to the synovial lining. Most of the cells were in the G0-phase. Ki-67 proliferation index was maximum 10% in synovial cells. Conclusion: The p53 pathway is activated in synovial cells in active RA as well as in quiescent stage of disease. Differences in the spatial expression pattern of proteins involved in the p53 pathway in RA in remission compared to actively proliferating RA reflect the phasic nature of the disease and support in our opinion the concept of adaptive role of p53 pathway in R