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Amelioration of Bleomycin-induced Pulmonary Fibrosis of Rats by an Aldose Reductase Inhibitor, Epalrestat.

Li X, Shen Y, Lu Y, Yang J - Korean J. Physiol. Pharmacol. (2015)

Bottom Line: Aldose reductase (AR) is known to play a crucial role in the mediation of diabetic and cardiovascular complications.Epalrestat is an aldose reductase inhibitor that is currently available for the treatment of diabetic neuropathy.Knockdown of AR gene expression reversed TGF-β1-induced proliferation of fibroblasts, up-regulation of α-SMA and collagen I expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Wannan Medical College, Wuhu 241002, China.

ABSTRACT
Aldose reductase (AR) is known to play a crucial role in the mediation of diabetic and cardiovascular complications. Recently, several studies have demonstrated that allergen-induced airway remodeling and ovalbumin-induced asthma is mediated by AR. Epalrestat is an aldose reductase inhibitor that is currently available for the treatment of diabetic neuropathy. Whether AR is involved in pathogenesis of pulmonary fibrosis and whether epalrestat attenuates pulmonary fibrosis remains unknown. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5 mg/kg) in rats. Primary pulmonary fibroblasts were cultured to investigate the proliferation by BrdU incorporation method and flow cytometry. The expression of AR, TGF-β1, α-SMA and collagen I was analyzed by immunohistochemisty, real-time PCR or western blot. In vivo, epalrestat treatment significantly ameliorated the bleomycin-mediated histological fibrosis alterations and blocked collagen deposition concomitantly with reversing bleomycin-induced expression up-regulation of TGF-β1, AR, α-SMA and collagen I (both mRNA and protein). In vitro, epalrestat remarkably attenuated proliferation of pulmonary fibroblasts and expression of α-SMA and collagen I induced by TGF-β1, and this inhibitory effect of epalrestat was accompanied by inhibiting AR expression. Knockdown of AR gene expression reversed TGF-β1-induced proliferation of fibroblasts, up-regulation of α-SMA and collagen I expression. These findings suggest that AR plays an important role in bleomycin-induced pulmonary fibrosis, and epalrestat inhibited the progression of bleomycin-induced pulmonary fibrosis is mediated via inhibiting of AR expression.

No MeSH data available.


Related in: MedlinePlus

Effect of epalrestat on TGF-β1-induced expression of AR and proliferation of pulmonary fibroblasts. (A) The expression of AR mRNA was determined by real-time PCR. (B) The expression of AR protein was determined by Western blot. (C) Cell proliferation was measured by BrdU incorporation assay. (D) The percentage of cells in S+G2 phase. (E) Cell cycle distribution was monitored by flow cytometry using a propidium iodide staining assay. The values are means±S.E.M. from three independent experiments in vitro. **p<0.01 vs. Control; #p<0.05, ##p<0.01 vs. TGF-β1. EPS, Epalrestat; AR, aldose reductase.
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Figure 4: Effect of epalrestat on TGF-β1-induced expression of AR and proliferation of pulmonary fibroblasts. (A) The expression of AR mRNA was determined by real-time PCR. (B) The expression of AR protein was determined by Western blot. (C) Cell proliferation was measured by BrdU incorporation assay. (D) The percentage of cells in S+G2 phase. (E) Cell cycle distribution was monitored by flow cytometry using a propidium iodide staining assay. The values are means±S.E.M. from three independent experiments in vitro. **p<0.01 vs. Control; #p<0.05, ##p<0.01 vs. TGF-β1. EPS, Epalrestat; AR, aldose reductase.

Mentions: TGF-β1 can induce the excessive proliferation and accumulation of pulmonary fibroblasts and promote the synthesis and deposition of collagen, which plays a crucial role in fibrotic diseases [33]. To investigate whether epalrestat inhibits AR expression directly, pulmonary fibroblasts were stimulated with TGF-β1 (5 ng/ml) in the presence or absence of epalrestat (1, 10, 100 µM) for the indicated time. As shown in Fig. 4A and B, exposure of fibroblasts to TGF-β1 for 24 h significantly increased mRNA and protein levels of AR, and epalrestat significantly inhibited the TGF-β1-induced upregulation of AR expression (both mRNA and protein) (p<0.05). However, epalrestat (100 µM) alone had no effect on AR expression in cultured pulmonary fibroblasts. We also found that exposure of pulmonary fibroblasts to TGF-β1 (5 ng/ml) for 24 h significantly increased the percentage of cells in the S+G2 phase and BrdU incorporation, and epalrestat (1, 10, 100 µM) significantly inhibited the TGF-β1-induced proliferation of pulmonary fibroblasts (p<0.05). Epalrestat (100 µM) alone had no effect on proliferation of pulmonary fibroblasts (Fig. 4C~E).


Amelioration of Bleomycin-induced Pulmonary Fibrosis of Rats by an Aldose Reductase Inhibitor, Epalrestat.

Li X, Shen Y, Lu Y, Yang J - Korean J. Physiol. Pharmacol. (2015)

Effect of epalrestat on TGF-β1-induced expression of AR and proliferation of pulmonary fibroblasts. (A) The expression of AR mRNA was determined by real-time PCR. (B) The expression of AR protein was determined by Western blot. (C) Cell proliferation was measured by BrdU incorporation assay. (D) The percentage of cells in S+G2 phase. (E) Cell cycle distribution was monitored by flow cytometry using a propidium iodide staining assay. The values are means±S.E.M. from three independent experiments in vitro. **p<0.01 vs. Control; #p<0.05, ##p<0.01 vs. TGF-β1. EPS, Epalrestat; AR, aldose reductase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4553399&req=5

Figure 4: Effect of epalrestat on TGF-β1-induced expression of AR and proliferation of pulmonary fibroblasts. (A) The expression of AR mRNA was determined by real-time PCR. (B) The expression of AR protein was determined by Western blot. (C) Cell proliferation was measured by BrdU incorporation assay. (D) The percentage of cells in S+G2 phase. (E) Cell cycle distribution was monitored by flow cytometry using a propidium iodide staining assay. The values are means±S.E.M. from three independent experiments in vitro. **p<0.01 vs. Control; #p<0.05, ##p<0.01 vs. TGF-β1. EPS, Epalrestat; AR, aldose reductase.
Mentions: TGF-β1 can induce the excessive proliferation and accumulation of pulmonary fibroblasts and promote the synthesis and deposition of collagen, which plays a crucial role in fibrotic diseases [33]. To investigate whether epalrestat inhibits AR expression directly, pulmonary fibroblasts were stimulated with TGF-β1 (5 ng/ml) in the presence or absence of epalrestat (1, 10, 100 µM) for the indicated time. As shown in Fig. 4A and B, exposure of fibroblasts to TGF-β1 for 24 h significantly increased mRNA and protein levels of AR, and epalrestat significantly inhibited the TGF-β1-induced upregulation of AR expression (both mRNA and protein) (p<0.05). However, epalrestat (100 µM) alone had no effect on AR expression in cultured pulmonary fibroblasts. We also found that exposure of pulmonary fibroblasts to TGF-β1 (5 ng/ml) for 24 h significantly increased the percentage of cells in the S+G2 phase and BrdU incorporation, and epalrestat (1, 10, 100 µM) significantly inhibited the TGF-β1-induced proliferation of pulmonary fibroblasts (p<0.05). Epalrestat (100 µM) alone had no effect on proliferation of pulmonary fibroblasts (Fig. 4C~E).

Bottom Line: Aldose reductase (AR) is known to play a crucial role in the mediation of diabetic and cardiovascular complications.Epalrestat is an aldose reductase inhibitor that is currently available for the treatment of diabetic neuropathy.Knockdown of AR gene expression reversed TGF-β1-induced proliferation of fibroblasts, up-regulation of α-SMA and collagen I expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Wannan Medical College, Wuhu 241002, China.

ABSTRACT
Aldose reductase (AR) is known to play a crucial role in the mediation of diabetic and cardiovascular complications. Recently, several studies have demonstrated that allergen-induced airway remodeling and ovalbumin-induced asthma is mediated by AR. Epalrestat is an aldose reductase inhibitor that is currently available for the treatment of diabetic neuropathy. Whether AR is involved in pathogenesis of pulmonary fibrosis and whether epalrestat attenuates pulmonary fibrosis remains unknown. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5 mg/kg) in rats. Primary pulmonary fibroblasts were cultured to investigate the proliferation by BrdU incorporation method and flow cytometry. The expression of AR, TGF-β1, α-SMA and collagen I was analyzed by immunohistochemisty, real-time PCR or western blot. In vivo, epalrestat treatment significantly ameliorated the bleomycin-mediated histological fibrosis alterations and blocked collagen deposition concomitantly with reversing bleomycin-induced expression up-regulation of TGF-β1, AR, α-SMA and collagen I (both mRNA and protein). In vitro, epalrestat remarkably attenuated proliferation of pulmonary fibroblasts and expression of α-SMA and collagen I induced by TGF-β1, and this inhibitory effect of epalrestat was accompanied by inhibiting AR expression. Knockdown of AR gene expression reversed TGF-β1-induced proliferation of fibroblasts, up-regulation of α-SMA and collagen I expression. These findings suggest that AR plays an important role in bleomycin-induced pulmonary fibrosis, and epalrestat inhibited the progression of bleomycin-induced pulmonary fibrosis is mediated via inhibiting of AR expression.

No MeSH data available.


Related in: MedlinePlus