Korean J Physiol Pharmacol.  2010 Jun;14(3):185-189. 10.4196/kjpp.2010.14.3.185.

Activation of PPARalpha Attenuates IFNgamma and IL-1beta-induced Cell Proliferation in Astrocytes: Involvement of IL-6 Independent Pathway

• Lee JK
• Seo EM
• Lee SS
• Park SH
• Sim YB
• Jung JS
• Kim SM
• Suh HW

• KMID: 2285401
• DOI: http://doi.org/10.4196/kjpp.2010.14.3.185

Abstract

The present study demonstrates the effect of fibrates, agonists of PPARalpha on cytokines-induced proliferation in primary cultured astrocytes. Alone or combination treatment with cytokines, such as IL-1beta (10 ng/ml), IFNgamma (10 ng/ml), and TNF-alpha (10 ng/ml) cause a significant increase of cell proliferation in a time-dependent manner. Treatment of astrocytes with bezafibrate and fenofibrate (0, 5, and 10 micrometer) reduced the IFNgamma and IL-1beta-induced cell proliferation in a dose-dependent manner. To address the involvement of IL-6 on the IFNgamma and IL-1beta-induced cell proliferation, released IL-6 level was measured. IFNgamma and IL-1beta cause an increase of released IL-6 protein level in a time-dependent manner. Furthermore, pretreatment with IL-6 antibody (0, 0.1, 1, 2.5, and 5 ng/ml) dose-dependently inhibited the IFNgamma and IL-1beta-induced cell proliferation. However, bezafibrate and fenofibrate did not affect increased mRNA and protein levels of IL-6 in IFNgamma and IL-1beta-stimulated astrocytes. Taken together, these results clearly suggest that activation of PPARalpha attenuates the IFNgamma and IL-1beta-induced cell proliferation through IL-6 independent pathway.

Keyword

Astrocytes; Bezafibrate; Fenofibrate; IL-6; Proliferation

MeSH Terms

Astrocytes
Bezafibrate
Cell Proliferation
Cytokines
Fenofibrate
Fibric Acids
Interleukin-6
PPAR alpha
RNA, Messenger
Tumor Necrosis Factor-alpha
Bezafibrate
Cytokines
Fenofibrate
Fibric Acids
Interleukin-6
PPAR alpha
RNA, Messenger
Tumor Necrosis Factor-alpha

Figure

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  Fig. 1. Effect of bezafibrate and fenofibrate on the cell proliferation in IFNγ and IL-1β-treated astrocytes. Cells were treated with TNF-α (10 ng/ml), IFN-γ (10 ng/ml), and IL-1β (10 ng/ml). (A) The effect of cytokines on astrocytes proliferation, assayed by BrdU incorporation, was examined at each time point (0, 6, 12, 18, and 24 hr) following alone or co-stimulation with cytokines. (B) The effect of fibrates on cell proliferation was assayed. Cells were preteated with bezafibrate and fenofibrate (0, 5, and 10 μM) for 0.5 hr before stimulation with IFN-γ and IL-1β. Data are represented as mean±S.D. from three independent experiments (∗∗p<0.01; vehicle vs. IFN-γ and IL-1β-treated group, +p<0.05; IFN-γ and IL-1β vs. IFN-γ and IL-1β plus fibrates-treated group).

• 

  Fig. 2. Involvement of IL-6 on the cell proliferation in IFNγ and IL-1β-treated astrocytes. Cells were treated with IFN-γ (10 ng/ml) and IL-1β (10 ng/ml). (A) Released IL-6 Protein levels were measured using IL-6 ELISA kit from cultured media after stimulation. Values are mean±S.D. (∗p<0.05, ∗∗p<0.01, ∗∗∗p<0.001; IFN-γ vs. IFN-γ and IL-1β). (B) The effect of antagonizing of IL-6 using antibody on cell proliferation was assayed. Cells were preteated with IL-6 antibody (sodium azaide free) (0, 0.5, 1, 2.5, and 5 ng/ml) for 0.5 hr before stimulation with IFN-γ and IL-1β. Data are represented as mean±S.D. from three independent experiments (∗∗∗p<0.001; vehicle vs. IFN-γ and IL-1β-treated group, +p<0.05, ++p<0.01, +++p<0.001; IFN-γ and IL-1β vs. IFN-γ and IL-1β plus IL-6 Ab-treated group).

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  Fig. 3. Effect of bezafibrate and fenofibrate on the expression of IL-6 in IFNγ and IL-1β-treated astrocytes. Cells were treated with IFN-γ (10 ng/ml) and IL-1β (10 ng/ml). (A) Released IL-6 Protein levels were measured using IL-6 ELISA kit from cultured media after stimulation. (B) Total RNA was isolated from 6 hr in IFN-γ and IL-1β-treated astrocytes. Gene expression of IL-6 was measured by quantitative real-time PCR using Rotor-Gene Q (Qiagen). The expression of IL-6 gene was normalized with GAPDH gene expression. Data were obtained from triplicated IL-6 ELISA and PCR reactions with three different cultures, and values are mean±S.D. (∗∗∗p<0.001; vehicle vs. IFN-γ and IL-1β).

Reference

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