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IL-17-mediated Bcl-2 expression regulates survival of fibroblast-like synoviocytes in rheumatoid arthritis through STAT3 activation.

Lee SY, Kwok SK, Son HJ, Ryu JG, Kim EK, Oh HJ, Cho ML, Ju JH, Park SH, Kim HY - Arthritis Res. Ther. (2013)

Bottom Line: The pro-apoptotic Bax is decreased and anti-apoptotic Bcl-2 is increased in FLSs from RA patients compared with those from patients with osteoarthritis (OA).STAT3 was found to mediate IL-17-induced Bcl-2 upregulation in FLSs from RA patients.Most importantly, treatment with STAT3 inhibitor reversed the protective effect of IL-17 on FLSs apoptosis induced by sodium nitroprusside (SNP).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Fibroblast-like synoviocytes (FLSs) are a major cell population of the pannus that invades adjacent cartilage and bone in rheumatoid arthritis (RA). The study was undertaken to determine the effect of interleukin-17 (IL-17) on the survival and/or proliferation of FLSs from RA patients and to investigate whether signal tranducer and activator of transcription 3 (STAT3) is implicated in this process.

Methods: Bcl-2 and Bax expression in FLSs was determined using the real-time PCR and western blot analysis. The expression of Bcl-2 and phosphoSTAT3 in synovial tissues was investigated by confocal microscope. Apoptosis of FLSs was detected by Annexin V/propidium iodide staining and/or phase contrast microscopy. The proliferation of FLSs was determined by CCK-8 ELISA assay.

Results: The pro-apoptotic Bax is decreased and anti-apoptotic Bcl-2 is increased in FLSs from RA patients compared with those from patients with osteoarthritis (OA). IL-17 upregulated the expression of Bcl-2 in FLSs from RA patients, but not in FLSs from OA patients. STAT3 was found to mediate IL-17-induced Bcl-2 upregulation in FLSs from RA patients. Additionally, IL-17 promoted the survival and proliferation of FLSs from RA patients. Most importantly, treatment with STAT3 inhibitor reversed the protective effect of IL-17 on FLSs apoptosis induced by sodium nitroprusside (SNP).

Conclusions: Our data demonstrate that STAT3 is critical in IL-17-induced survival of FLS from RA patients. Therefore, therapeutic strategies that target the IL-17/STAT3 pathway might be strong candidates for RA treatment modalities.

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Signal tranducer and activator of transcription 3 (STAT3) mediates IL-17-induced Bcl-2 upregulation in synoviocytes in rheumatoid arthritis (RA). (A) IL-17 upregulated the expression of STAT3 in RA-fibroblast-like synoviocytes (FLSs). RA-FLSs (n = 3) were cultured with IL-17 (0, 1 and 10 ng/ml) for 12 hours. The expressions of STAT3 and phosphorylated STAT3 (pSTAT3 705 and pSTAT3 727) were measured by western blot. The representative figure is shown in the left panel. Data are expressed as mean ± SD of three independent experiments. *P < 0.05, **P < 0.01 compared with the untreated group. (B) RA-FLSs (n = 3) were cultured with IL-17 (0 and 10 ng/ml) in the presence or absence of STAT3 inhibitor (STA21 50 μM) for 12 hours. The expression of Bcl-2 mRNA and protein was evaluated by real-time PCR and western blot. (C) Co-localization of STAT3 and Bcl-2 in rheumatoid synovium. Tissue sections from the synovium of patients with RA (n = 3) or osteoarthritis (OA) (n = 3) were stained with anti-Bcl-2, anti- pSTAT3 727 and anti-pSTAT3 705 antibodies. Co-localization of STAT3 and Bcl-2 was observed in synovial lining cells of RA patients. The representative figure is shown.
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Figure 3: Signal tranducer and activator of transcription 3 (STAT3) mediates IL-17-induced Bcl-2 upregulation in synoviocytes in rheumatoid arthritis (RA). (A) IL-17 upregulated the expression of STAT3 in RA-fibroblast-like synoviocytes (FLSs). RA-FLSs (n = 3) were cultured with IL-17 (0, 1 and 10 ng/ml) for 12 hours. The expressions of STAT3 and phosphorylated STAT3 (pSTAT3 705 and pSTAT3 727) were measured by western blot. The representative figure is shown in the left panel. Data are expressed as mean ± SD of three independent experiments. *P < 0.05, **P < 0.01 compared with the untreated group. (B) RA-FLSs (n = 3) were cultured with IL-17 (0 and 10 ng/ml) in the presence or absence of STAT3 inhibitor (STA21 50 μM) for 12 hours. The expression of Bcl-2 mRNA and protein was evaluated by real-time PCR and western blot. (C) Co-localization of STAT3 and Bcl-2 in rheumatoid synovium. Tissue sections from the synovium of patients with RA (n = 3) or osteoarthritis (OA) (n = 3) were stained with anti-Bcl-2, anti- pSTAT3 727 and anti-pSTAT3 705 antibodies. Co-localization of STAT3 and Bcl-2 was observed in synovial lining cells of RA patients. The representative figure is shown.

Mentions: We examined whether IL-17 activates STAT3 in FLSs from RA patients. We observed that IL-17 treatment increased phosphorylated STAT3 (p-STAT3 705 and p-STAT3 727) in FLSs from RA patients, demonstrating that IL-17 activated STAT3 (Figure 3A). We also found that treatment with STA21, a STAT3 inhibitor, abrogated IL-17-induced Bcl-2 expression in FLSs from RA patients (Figure 3B), demonstrating that STAT3 is involved in IL-17-induced Bcl-2 expression. When we cultured FLSs from RA patients with STA21 in the absence of IL-17, STA21 did not cause significant impact on the expression of Bcl-2 (data not shown).


IL-17-mediated Bcl-2 expression regulates survival of fibroblast-like synoviocytes in rheumatoid arthritis through STAT3 activation.

Lee SY, Kwok SK, Son HJ, Ryu JG, Kim EK, Oh HJ, Cho ML, Ju JH, Park SH, Kim HY - Arthritis Res. Ther. (2013)

Signal tranducer and activator of transcription 3 (STAT3) mediates IL-17-induced Bcl-2 upregulation in synoviocytes in rheumatoid arthritis (RA). (A) IL-17 upregulated the expression of STAT3 in RA-fibroblast-like synoviocytes (FLSs). RA-FLSs (n = 3) were cultured with IL-17 (0, 1 and 10 ng/ml) for 12 hours. The expressions of STAT3 and phosphorylated STAT3 (pSTAT3 705 and pSTAT3 727) were measured by western blot. The representative figure is shown in the left panel. Data are expressed as mean ± SD of three independent experiments. *P < 0.05, **P < 0.01 compared with the untreated group. (B) RA-FLSs (n = 3) were cultured with IL-17 (0 and 10 ng/ml) in the presence or absence of STAT3 inhibitor (STA21 50 μM) for 12 hours. The expression of Bcl-2 mRNA and protein was evaluated by real-time PCR and western blot. (C) Co-localization of STAT3 and Bcl-2 in rheumatoid synovium. Tissue sections from the synovium of patients with RA (n = 3) or osteoarthritis (OA) (n = 3) were stained with anti-Bcl-2, anti- pSTAT3 727 and anti-pSTAT3 705 antibodies. Co-localization of STAT3 and Bcl-2 was observed in synovial lining cells of RA patients. The representative figure is shown.
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Figure 3: Signal tranducer and activator of transcription 3 (STAT3) mediates IL-17-induced Bcl-2 upregulation in synoviocytes in rheumatoid arthritis (RA). (A) IL-17 upregulated the expression of STAT3 in RA-fibroblast-like synoviocytes (FLSs). RA-FLSs (n = 3) were cultured with IL-17 (0, 1 and 10 ng/ml) for 12 hours. The expressions of STAT3 and phosphorylated STAT3 (pSTAT3 705 and pSTAT3 727) were measured by western blot. The representative figure is shown in the left panel. Data are expressed as mean ± SD of three independent experiments. *P < 0.05, **P < 0.01 compared with the untreated group. (B) RA-FLSs (n = 3) were cultured with IL-17 (0 and 10 ng/ml) in the presence or absence of STAT3 inhibitor (STA21 50 μM) for 12 hours. The expression of Bcl-2 mRNA and protein was evaluated by real-time PCR and western blot. (C) Co-localization of STAT3 and Bcl-2 in rheumatoid synovium. Tissue sections from the synovium of patients with RA (n = 3) or osteoarthritis (OA) (n = 3) were stained with anti-Bcl-2, anti- pSTAT3 727 and anti-pSTAT3 705 antibodies. Co-localization of STAT3 and Bcl-2 was observed in synovial lining cells of RA patients. The representative figure is shown.
Mentions: We examined whether IL-17 activates STAT3 in FLSs from RA patients. We observed that IL-17 treatment increased phosphorylated STAT3 (p-STAT3 705 and p-STAT3 727) in FLSs from RA patients, demonstrating that IL-17 activated STAT3 (Figure 3A). We also found that treatment with STA21, a STAT3 inhibitor, abrogated IL-17-induced Bcl-2 expression in FLSs from RA patients (Figure 3B), demonstrating that STAT3 is involved in IL-17-induced Bcl-2 expression. When we cultured FLSs from RA patients with STA21 in the absence of IL-17, STA21 did not cause significant impact on the expression of Bcl-2 (data not shown).

Bottom Line: The pro-apoptotic Bax is decreased and anti-apoptotic Bcl-2 is increased in FLSs from RA patients compared with those from patients with osteoarthritis (OA).STAT3 was found to mediate IL-17-induced Bcl-2 upregulation in FLSs from RA patients.Most importantly, treatment with STAT3 inhibitor reversed the protective effect of IL-17 on FLSs apoptosis induced by sodium nitroprusside (SNP).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Fibroblast-like synoviocytes (FLSs) are a major cell population of the pannus that invades adjacent cartilage and bone in rheumatoid arthritis (RA). The study was undertaken to determine the effect of interleukin-17 (IL-17) on the survival and/or proliferation of FLSs from RA patients and to investigate whether signal tranducer and activator of transcription 3 (STAT3) is implicated in this process.

Methods: Bcl-2 and Bax expression in FLSs was determined using the real-time PCR and western blot analysis. The expression of Bcl-2 and phosphoSTAT3 in synovial tissues was investigated by confocal microscope. Apoptosis of FLSs was detected by Annexin V/propidium iodide staining and/or phase contrast microscopy. The proliferation of FLSs was determined by CCK-8 ELISA assay.

Results: The pro-apoptotic Bax is decreased and anti-apoptotic Bcl-2 is increased in FLSs from RA patients compared with those from patients with osteoarthritis (OA). IL-17 upregulated the expression of Bcl-2 in FLSs from RA patients, but not in FLSs from OA patients. STAT3 was found to mediate IL-17-induced Bcl-2 upregulation in FLSs from RA patients. Additionally, IL-17 promoted the survival and proliferation of FLSs from RA patients. Most importantly, treatment with STAT3 inhibitor reversed the protective effect of IL-17 on FLSs apoptosis induced by sodium nitroprusside (SNP).

Conclusions: Our data demonstrate that STAT3 is critical in IL-17-induced survival of FLS from RA patients. Therefore, therapeutic strategies that target the IL-17/STAT3 pathway might be strong candidates for RA treatment modalities.

Show MeSH
Related in: MedlinePlus