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Citrullinated fibronectin inhibits apoptosis and promotes the secretion of pro-inflammatory cytokines in fibroblast-like synoviocytes in rheumatoid arthritis.

Fan L, Wang Q, Liu R, Zong M, He D, Zhang H, Ding Y, Ma J - Arthritis Res. Ther. (2012)

Bottom Line: Fn induced the apoptosis of RA and OA FLSs while cFn inhibited the apoptosis of RA and OA FLSs.Fn significantly increased the expression of caspase-3 and decreased the expression of survivin and cyclin-B1 in FLSs from RA and OA patients. cFn significantly increased the expression of survivin in RA FLSs.Furthermore, cFn increased the secretion of TNF-α and IL-1 by FLSs. cFn plays a potential pathophysiologic role in RA by inhibiting apoptosis and increasing proinflammatory cytokine secretion of FLSs.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Rheumatoid arthritis (RA) is characterized by synovial lining hyperplasia, in which there may be an imbalance between the growth and death of fibroblast-like synoviocytes (FLSs). Antibodies against citrullinated proteins are proposed to induce RA. This study aimed to investigate the pathogenic role of citrullinated fibronectin (cFn) in RA.

Methods: The distribution of fibronectin (Fn) and cFn in synovial tissues from RA and osteoarthritis (OA) patients was examined by immunohistochemical and double immunofluorescence analysis. FLSs were isolated from RA and OA patients and treated with Fn or cFn. Apoptosis was detected by flow cytometry and TUNEL assay. The expression of survivin, caspase-3, cyclin-B1, Bcl-2 and Bax was detected by real-time PCR. The secretion of proinflammatory cytokines was measured by ELISA.

Results: Fn formed extracellular aggregates that were specifically citrullinated in synovial tissues of RA patients, but no Fn deposits were observed in those of OA patients. Fn induced the apoptosis of RA and OA FLSs while cFn inhibited the apoptosis of RA and OA FLSs. Fn significantly increased the expression of caspase-3 and decreased the expression of survivin and cyclin-B1 in FLSs from RA and OA patients. cFn significantly increased the expression of survivin in RA FLSs. Furthermore, cFn increased the secretion of TNF-α and IL-1 by FLSs.

Conclusions: cFn plays a potential pathophysiologic role in RA by inhibiting apoptosis and increasing proinflammatory cytokine secretion of FLSs.

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The effects of Fn and cFn on the expression of apoptosis-related molecules in FLSs isolated from RA or OA patients. RA or OA FLSs were treated with Fn or cFn at 2 μg/ml for 72 h and total RNA was isolated for the analysis of survivin, caspase 3, cyclin-B1, Bcl-2 and Bax mRNA levels. RA (n = 8) and OA (n = 6). * P < 0.05 compared with blank, ** P < 0.01 compared with blank. Δ P < 0.05 compared with cFn, ΔΔ P < 0.01 compared with cFn. cFn, citrullinated fibronectin; FLSs, fibroblast-like synoviocytes; Fn, fibronectin; OA, osteoarthritis; RA, rheumatoid arthritis.
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Figure 3: The effects of Fn and cFn on the expression of apoptosis-related molecules in FLSs isolated from RA or OA patients. RA or OA FLSs were treated with Fn or cFn at 2 μg/ml for 72 h and total RNA was isolated for the analysis of survivin, caspase 3, cyclin-B1, Bcl-2 and Bax mRNA levels. RA (n = 8) and OA (n = 6). * P < 0.05 compared with blank, ** P < 0.01 compared with blank. Δ P < 0.05 compared with cFn, ΔΔ P < 0.01 compared with cFn. cFn, citrullinated fibronectin; FLSs, fibroblast-like synoviocytes; Fn, fibronectin; OA, osteoarthritis; RA, rheumatoid arthritis.

Mentions: To further elucidate the molecular mechanisms of Fn-induced apoptosis of FLSs, we examined the effects of Fn and cFn on the expression of apoptosis-related molecules. Fn significantly decreased the expression of survivin and cyclin-B1, but increased the expression of caspase 3 in FLSs from RA and OA (P < 0.05, Figure 3). In contrast, cFn significantly increased the expression of survivin in FLSs isolated from RA (P < 0.01). The expression of both Bcl-2 and Bax was not different in FLSs treated by 2 μg/ml Fn or cFn compared with treated control FLSs. These results suggest that survivin is implicated in Fn-induced apoptosis of FLS.


Citrullinated fibronectin inhibits apoptosis and promotes the secretion of pro-inflammatory cytokines in fibroblast-like synoviocytes in rheumatoid arthritis.

Fan L, Wang Q, Liu R, Zong M, He D, Zhang H, Ding Y, Ma J - Arthritis Res. Ther. (2012)

The effects of Fn and cFn on the expression of apoptosis-related molecules in FLSs isolated from RA or OA patients. RA or OA FLSs were treated with Fn or cFn at 2 μg/ml for 72 h and total RNA was isolated for the analysis of survivin, caspase 3, cyclin-B1, Bcl-2 and Bax mRNA levels. RA (n = 8) and OA (n = 6). * P < 0.05 compared with blank, ** P < 0.01 compared with blank. Δ P < 0.05 compared with cFn, ΔΔ P < 0.01 compared with cFn. cFn, citrullinated fibronectin; FLSs, fibroblast-like synoviocytes; Fn, fibronectin; OA, osteoarthritis; RA, rheumatoid arthritis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3674622&req=5

Figure 3: The effects of Fn and cFn on the expression of apoptosis-related molecules in FLSs isolated from RA or OA patients. RA or OA FLSs were treated with Fn or cFn at 2 μg/ml for 72 h and total RNA was isolated for the analysis of survivin, caspase 3, cyclin-B1, Bcl-2 and Bax mRNA levels. RA (n = 8) and OA (n = 6). * P < 0.05 compared with blank, ** P < 0.01 compared with blank. Δ P < 0.05 compared with cFn, ΔΔ P < 0.01 compared with cFn. cFn, citrullinated fibronectin; FLSs, fibroblast-like synoviocytes; Fn, fibronectin; OA, osteoarthritis; RA, rheumatoid arthritis.
Mentions: To further elucidate the molecular mechanisms of Fn-induced apoptosis of FLSs, we examined the effects of Fn and cFn on the expression of apoptosis-related molecules. Fn significantly decreased the expression of survivin and cyclin-B1, but increased the expression of caspase 3 in FLSs from RA and OA (P < 0.05, Figure 3). In contrast, cFn significantly increased the expression of survivin in FLSs isolated from RA (P < 0.01). The expression of both Bcl-2 and Bax was not different in FLSs treated by 2 μg/ml Fn or cFn compared with treated control FLSs. These results suggest that survivin is implicated in Fn-induced apoptosis of FLS.

Bottom Line: Fn induced the apoptosis of RA and OA FLSs while cFn inhibited the apoptosis of RA and OA FLSs.Fn significantly increased the expression of caspase-3 and decreased the expression of survivin and cyclin-B1 in FLSs from RA and OA patients. cFn significantly increased the expression of survivin in RA FLSs.Furthermore, cFn increased the secretion of TNF-α and IL-1 by FLSs. cFn plays a potential pathophysiologic role in RA by inhibiting apoptosis and increasing proinflammatory cytokine secretion of FLSs.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Rheumatoid arthritis (RA) is characterized by synovial lining hyperplasia, in which there may be an imbalance between the growth and death of fibroblast-like synoviocytes (FLSs). Antibodies against citrullinated proteins are proposed to induce RA. This study aimed to investigate the pathogenic role of citrullinated fibronectin (cFn) in RA.

Methods: The distribution of fibronectin (Fn) and cFn in synovial tissues from RA and osteoarthritis (OA) patients was examined by immunohistochemical and double immunofluorescence analysis. FLSs were isolated from RA and OA patients and treated with Fn or cFn. Apoptosis was detected by flow cytometry and TUNEL assay. The expression of survivin, caspase-3, cyclin-B1, Bcl-2 and Bax was detected by real-time PCR. The secretion of proinflammatory cytokines was measured by ELISA.

Results: Fn formed extracellular aggregates that were specifically citrullinated in synovial tissues of RA patients, but no Fn deposits were observed in those of OA patients. Fn induced the apoptosis of RA and OA FLSs while cFn inhibited the apoptosis of RA and OA FLSs. Fn significantly increased the expression of caspase-3 and decreased the expression of survivin and cyclin-B1 in FLSs from RA and OA patients. cFn significantly increased the expression of survivin in RA FLSs. Furthermore, cFn increased the secretion of TNF-α and IL-1 by FLSs.

Conclusions: cFn plays a potential pathophysiologic role in RA by inhibiting apoptosis and increasing proinflammatory cytokine secretion of FLSs.

Show MeSH
Related in: MedlinePlus