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Immunohistochemical localization of transforming growth factor β-1 and its relationship with collagen expression in advanced liver fibrosis due to biliary atresia.

Farrington C, Novak D, Liu C, Haafiz AB - Clin Exp Gastroenterol (2010)

Bottom Line: The intensities of portal and lobular TGFβ1 expressions were compared.The results obtained by coimmunofluorescence staining showed no colocalization of α-SMA and TGFβ1.These findings suggest a paracrine mechanisms of TGFβ1-driven fibrogenesis in advanced BA.

View Article: PubMed Central - PubMed

Affiliation: Hepatology and Liver Transplantation, Division of Pediatric Gastroenterology, Hepatology and Nutrition.

ABSTRACT

Purpose: Biliary atresia (BA) is the most common indication of liver transplantation in children. Pathogenesis of hepatic fibrosis, which is a prominent feature of BA, remains obscure. The purpose of this work was to determine the cellular sources of transforming growth factor beta-1 (TGFβ1) and establish the relationship between TGFβ1-producing cells and extracellular matrix producing myofibroblasts (MFBs) in advanced BA.

Methods: Trichrome staining and immunohistochemistry were carried out to determine the expression pattern of collagen and TGFβ1 protein in explant liver specimens from patients with BA. The intensities of portal and lobular TGFβ1 expressions were compared. Immunofluorescence technique was carried out to determine the relationship between α-smooth muscle actin (α-SMA)-positive-MFB and TGFβ1-positve cells.

Results: Lobular TGFβ1 protein expression was significantly higher than portal (89 ± 6 versus 10 ± 1 arbitrary units, P ≤ 0.05), whereas no difference was noted in livers used as control (10 ± 1.6 versus 19 ± 5 arbitrary units, P = 0.11). TGFβ1 expression was more in the center of nodules versus MFB in surrounding fibrous septa. Contrary to TGFβ1 expression, α1-SMA was mostly expressed in the portal structures and the adjacent fibrous septa enacting lobulation of the parenchyma. The results obtained by coimmunofluorescence staining showed no colocalization of α-SMA and TGFβ1.

Conclusions: TGFβ1 protein expression is mostly localized to hepatocytes in advanced BA. These findings suggest a paracrine mechanisms of TGFβ1-driven fibrogenesis in advanced BA.

No MeSH data available.


Related in: MedlinePlus

Immunohistochemical localization of TGFβ1 protein in human BA. Specific staining of TGFβ1 protein is represented by brown coloration. A) The expression of TGFβ1 in BA, which is mostly in lobular areas. B) TGFβ1 expression in a liver used as control. C) Expression of α1-SMA in BA. D) α1-SMA from a liver used as control (original magnification ×10).Abbreviations: TGFβ1, transforming growth factor beta-1; BA, biliary atresia; SMA, smooth muscle actin.
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f2-ceg-3-185: Immunohistochemical localization of TGFβ1 protein in human BA. Specific staining of TGFβ1 protein is represented by brown coloration. A) The expression of TGFβ1 in BA, which is mostly in lobular areas. B) TGFβ1 expression in a liver used as control. C) Expression of α1-SMA in BA. D) α1-SMA from a liver used as control (original magnification ×10).Abbreviations: TGFβ1, transforming growth factor beta-1; BA, biliary atresia; SMA, smooth muscle actin.

Mentions: In explant liver specimens, as shown in Figure 2A, heterogeneous overexpression of TGFβ1 is evident in the hepatic parenchyma, more in the center of the liver nodules, although hepatocytes close to collagen in fibrous septa are also noted to express a low level of TGFβ1 protein. Conversely, in livers used as control, the distribution of TGFβ1 is virtually all interstitial and quite homogeneous throughout the hepatic parenchyma (Figure 2B). Contrary to TGFβ1 expression, α-SMA is expressed mostly in the portal structures and the adjacent fibrous septa enacting lobulation of the parenchyma (Figure 2C). As expected, in liver specimens used as control, α-SMA expression is restricted to portal structures (Figure 2D). Consistent with the TGFβ1 expression in hepatic parenchyma, quantitative analysis of TGFβ1 protein content was significantly higher in lobular versus portal areas (89 ± 6 versus 10 ± 1 arbitrary units, P ≤ 0.05) in BA (Figure 3). In contrast, in livers used as control, lobular versus portal TGFβ1 expression was not significantly different, although a trend of more portal expression was noted (10 ± 1.6 versus 19 ± 5 arbitrary units, P = 0.11; Figure 3). These results were in agreement with the coimmunofluorescence staining, which showed no significant localization of α-SMA and TGFβ1 (Figure 4C and D). Once again, most of the TGFβ1 expression is seen in parenchymal cells (Figure 4A, C and D), whereas α-SMA expression is mostly restricted to the area of fibrous septa (Figure 4B). The summary of these findings is that in advanced BA, TGFβ1 is mainly expressed by hepatic parenchymal cells.


Immunohistochemical localization of transforming growth factor β-1 and its relationship with collagen expression in advanced liver fibrosis due to biliary atresia.

Farrington C, Novak D, Liu C, Haafiz AB - Clin Exp Gastroenterol (2010)

Immunohistochemical localization of TGFβ1 protein in human BA. Specific staining of TGFβ1 protein is represented by brown coloration. A) The expression of TGFβ1 in BA, which is mostly in lobular areas. B) TGFβ1 expression in a liver used as control. C) Expression of α1-SMA in BA. D) α1-SMA from a liver used as control (original magnification ×10).Abbreviations: TGFβ1, transforming growth factor beta-1; BA, biliary atresia; SMA, smooth muscle actin.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3108674&req=5

f2-ceg-3-185: Immunohistochemical localization of TGFβ1 protein in human BA. Specific staining of TGFβ1 protein is represented by brown coloration. A) The expression of TGFβ1 in BA, which is mostly in lobular areas. B) TGFβ1 expression in a liver used as control. C) Expression of α1-SMA in BA. D) α1-SMA from a liver used as control (original magnification ×10).Abbreviations: TGFβ1, transforming growth factor beta-1; BA, biliary atresia; SMA, smooth muscle actin.
Mentions: In explant liver specimens, as shown in Figure 2A, heterogeneous overexpression of TGFβ1 is evident in the hepatic parenchyma, more in the center of the liver nodules, although hepatocytes close to collagen in fibrous septa are also noted to express a low level of TGFβ1 protein. Conversely, in livers used as control, the distribution of TGFβ1 is virtually all interstitial and quite homogeneous throughout the hepatic parenchyma (Figure 2B). Contrary to TGFβ1 expression, α-SMA is expressed mostly in the portal structures and the adjacent fibrous septa enacting lobulation of the parenchyma (Figure 2C). As expected, in liver specimens used as control, α-SMA expression is restricted to portal structures (Figure 2D). Consistent with the TGFβ1 expression in hepatic parenchyma, quantitative analysis of TGFβ1 protein content was significantly higher in lobular versus portal areas (89 ± 6 versus 10 ± 1 arbitrary units, P ≤ 0.05) in BA (Figure 3). In contrast, in livers used as control, lobular versus portal TGFβ1 expression was not significantly different, although a trend of more portal expression was noted (10 ± 1.6 versus 19 ± 5 arbitrary units, P = 0.11; Figure 3). These results were in agreement with the coimmunofluorescence staining, which showed no significant localization of α-SMA and TGFβ1 (Figure 4C and D). Once again, most of the TGFβ1 expression is seen in parenchymal cells (Figure 4A, C and D), whereas α-SMA expression is mostly restricted to the area of fibrous septa (Figure 4B). The summary of these findings is that in advanced BA, TGFβ1 is mainly expressed by hepatic parenchymal cells.

Bottom Line: The intensities of portal and lobular TGFβ1 expressions were compared.The results obtained by coimmunofluorescence staining showed no colocalization of α-SMA and TGFβ1.These findings suggest a paracrine mechanisms of TGFβ1-driven fibrogenesis in advanced BA.

View Article: PubMed Central - PubMed

Affiliation: Hepatology and Liver Transplantation, Division of Pediatric Gastroenterology, Hepatology and Nutrition.

ABSTRACT

Purpose: Biliary atresia (BA) is the most common indication of liver transplantation in children. Pathogenesis of hepatic fibrosis, which is a prominent feature of BA, remains obscure. The purpose of this work was to determine the cellular sources of transforming growth factor beta-1 (TGFβ1) and establish the relationship between TGFβ1-producing cells and extracellular matrix producing myofibroblasts (MFBs) in advanced BA.

Methods: Trichrome staining and immunohistochemistry were carried out to determine the expression pattern of collagen and TGFβ1 protein in explant liver specimens from patients with BA. The intensities of portal and lobular TGFβ1 expressions were compared. Immunofluorescence technique was carried out to determine the relationship between α-smooth muscle actin (α-SMA)-positive-MFB and TGFβ1-positve cells.

Results: Lobular TGFβ1 protein expression was significantly higher than portal (89 ± 6 versus 10 ± 1 arbitrary units, P ≤ 0.05), whereas no difference was noted in livers used as control (10 ± 1.6 versus 19 ± 5 arbitrary units, P = 0.11). TGFβ1 expression was more in the center of nodules versus MFB in surrounding fibrous septa. Contrary to TGFβ1 expression, α1-SMA was mostly expressed in the portal structures and the adjacent fibrous septa enacting lobulation of the parenchyma. The results obtained by coimmunofluorescence staining showed no colocalization of α-SMA and TGFβ1.

Conclusions: TGFβ1 protein expression is mostly localized to hepatocytes in advanced BA. These findings suggest a paracrine mechanisms of TGFβ1-driven fibrogenesis in advanced BA.

No MeSH data available.


Related in: MedlinePlus