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Knockout of microRNA-21 reduces biliary hyperplasia and liver fibrosis in cholestatic bile duct ligated mice

View Article: PubMed Central - PubMed

ABSTRACT

Cholestasis is a condition that leads to chronic hepatobiliary inflammation, fibrosis, and eventually cirrhosis. Many microRNAs (miRs) are known to play a role in fibrosis progression; however, the role of miR-21 during cholestasis remains unknown. Therefore, the aim of this study was to elucidate the role of miR-21 during cholestasis-induced biliary hyperplasia and hepatic fibrosis. Wild-type (WT) and miR21−/− mice underwent sham or bile duct ligation (BDL) for 1 wk, before evaluating liver histology, biliary proliferation, hepatic stellate cell (HSC) activation, fibrotic response, and Smad-7 expression. In vitro, immortalized murine biliary cell lines (IMCL) and human hepatic stellate cell line (hHSC) were treated with either miR-21 inhibitor or control before analyzing proliferation, apoptosis, and fibrotic responses. In vivo, the levels of miR-21 were increased in total liver and cholangiocytes after BDL, and loss of miR-21 decreased the amount of BDL-induced biliary proliferation and intrahepatic biliary mass. Also, loss of miR-21 decreased BDL-induced HSC activation, collagen deposition, and expression of the fibrotic markers TGF-β1 and α-SMA. In vitro, IMCL and hHSCs treated with miR-21 inhibitor displayed decreased proliferation and expression of fibrotic markers and enhanced apoptosis when compared to control treated cells. Furthermore, mice lacking miR-21 show increased Smad-7 expression, which may be driving the decrease in biliary hyperplasia and hepatic fibrosis. During cholestatic injury miR-21 is increased and leads to increased biliary proliferation and hepatic fibrosis. Local modulation of miR-21 may be a therapeutic option for patients with cholestasis.

No MeSH data available.


Related in: MedlinePlus

Assessment of liver injury. Loss of miR-21 ameliorates BDL-induced necrosis, lobular damage, and portal inflammation as indicated by H&E staining (A). Yellow dashed line indicates areas of necrosis while the yellow arrows point to bile ducts (A). BDL WT mice show increased serum levels of ALT and ALP when compared to BDL WT; however, these parameters are decreased in BDL miR-21−/− mice when compared to BDL WT mice (B). Data are expressed as means ± SEM. n = 3 reactions in serum collected from 8 animals each per animal group for serum chemistry. *p<0.05 versus Sham WT; #p<0.05 versus BDL WT. Representative images are shown for H&E. Original magnification, 20X.
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Figure 2: Assessment of liver injury. Loss of miR-21 ameliorates BDL-induced necrosis, lobular damage, and portal inflammation as indicated by H&E staining (A). Yellow dashed line indicates areas of necrosis while the yellow arrows point to bile ducts (A). BDL WT mice show increased serum levels of ALT and ALP when compared to BDL WT; however, these parameters are decreased in BDL miR-21−/− mice when compared to BDL WT mice (B). Data are expressed as means ± SEM. n = 3 reactions in serum collected from 8 animals each per animal group for serum chemistry. *p<0.05 versus Sham WT; #p<0.05 versus BDL WT. Representative images are shown for H&E. Original magnification, 20X.

Mentions: Following BDL, there was moderate portal inflammation, ductal proliferation, and multifocal areas of necrosis when compared to Sham WT mice; however, the amount of damage observed in BDL miR-21−/− mice was greatly decreased when compared to BDL WT mice suggesting that miR-21 promotes liver damage during cholestatic injury (Figure 2A). No significant changes were noted in Sham miR-21−/− mice compared to Sham WT (Figure 2A). Similarly, the levels of the liver enzymes alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were increased in serum from BDL WT compared to Sham WT mice; however, ALT and ALP serum levels were decreased in BDL miR-21−/− mice compared to BDL WT mice (Figure 2B). These studies indicate that the loss of miR-21 during BDL-induced cholestatic injury ameliorates liver damage associated with this injury.


Knockout of microRNA-21 reduces biliary hyperplasia and liver fibrosis in cholestatic bile duct ligated mice
Assessment of liver injury. Loss of miR-21 ameliorates BDL-induced necrosis, lobular damage, and portal inflammation as indicated by H&E staining (A). Yellow dashed line indicates areas of necrosis while the yellow arrows point to bile ducts (A). BDL WT mice show increased serum levels of ALT and ALP when compared to BDL WT; however, these parameters are decreased in BDL miR-21−/− mice when compared to BDL WT mice (B). Data are expressed as means ± SEM. n = 3 reactions in serum collected from 8 animals each per animal group for serum chemistry. *p<0.05 versus Sham WT; #p<0.05 versus BDL WT. Representative images are shown for H&E. Original magnification, 20X.
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Related In: Results  -  Collection

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Figure 2: Assessment of liver injury. Loss of miR-21 ameliorates BDL-induced necrosis, lobular damage, and portal inflammation as indicated by H&E staining (A). Yellow dashed line indicates areas of necrosis while the yellow arrows point to bile ducts (A). BDL WT mice show increased serum levels of ALT and ALP when compared to BDL WT; however, these parameters are decreased in BDL miR-21−/− mice when compared to BDL WT mice (B). Data are expressed as means ± SEM. n = 3 reactions in serum collected from 8 animals each per animal group for serum chemistry. *p<0.05 versus Sham WT; #p<0.05 versus BDL WT. Representative images are shown for H&E. Original magnification, 20X.
Mentions: Following BDL, there was moderate portal inflammation, ductal proliferation, and multifocal areas of necrosis when compared to Sham WT mice; however, the amount of damage observed in BDL miR-21−/− mice was greatly decreased when compared to BDL WT mice suggesting that miR-21 promotes liver damage during cholestatic injury (Figure 2A). No significant changes were noted in Sham miR-21−/− mice compared to Sham WT (Figure 2A). Similarly, the levels of the liver enzymes alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were increased in serum from BDL WT compared to Sham WT mice; however, ALT and ALP serum levels were decreased in BDL miR-21−/− mice compared to BDL WT mice (Figure 2B). These studies indicate that the loss of miR-21 during BDL-induced cholestatic injury ameliorates liver damage associated with this injury.

View Article: PubMed Central - PubMed

ABSTRACT

Cholestasis is a condition that leads to chronic hepatobiliary inflammation, fibrosis, and eventually cirrhosis. Many microRNAs (miRs) are known to play a role in fibrosis progression; however, the role of miR-21 during cholestasis remains unknown. Therefore, the aim of this study was to elucidate the role of miR-21 during cholestasis-induced biliary hyperplasia and hepatic fibrosis. Wild-type (WT) and miR21&minus;/&minus; mice underwent sham or bile duct ligation (BDL) for 1 wk, before evaluating liver histology, biliary proliferation, hepatic stellate cell (HSC) activation, fibrotic response, and Smad-7 expression. In vitro, immortalized murine biliary cell lines (IMCL) and human hepatic stellate cell line (hHSC) were treated with either miR-21 inhibitor or control before analyzing proliferation, apoptosis, and fibrotic responses. In vivo, the levels of miR-21 were increased in total liver and cholangiocytes after BDL, and loss of miR-21 decreased the amount of BDL-induced biliary proliferation and intrahepatic biliary mass. Also, loss of miR-21 decreased BDL-induced HSC activation, collagen deposition, and expression of the fibrotic markers TGF-&beta;1 and &alpha;-SMA. In vitro, IMCL and hHSCs treated with miR-21 inhibitor displayed decreased proliferation and expression of fibrotic markers and enhanced apoptosis when compared to control treated cells. Furthermore, mice lacking miR-21 show increased Smad-7 expression, which may be driving the decrease in biliary hyperplasia and hepatic fibrosis. During cholestatic injury miR-21 is increased and leads to increased biliary proliferation and hepatic fibrosis. Local modulation of miR-21 may be a therapeutic option for patients with cholestasis.

No MeSH data available.


Related in: MedlinePlus