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TRAIL-producing NK cells contribute to liver injury and related fibrogenesis in the context of GNMT deficiency.

Fernández-Álvarez S, Gutiérrez-de Juan V, Zubiete-Franco I, Barbier-Torres L, Lahoz A, Parés A, Luka Z, Wagner C, Lu SC, Mato JM, Martínez-Chantar ML, Beraza N - Lab. Invest. (2014)

Bottom Line: Glycine-N-methyltransferase (GNMT) is essential to preserve liver homeostasis.The aim of our study is to elucidate the implication of TRAIL-producing NK cells in the progression of chronic liver injury and fibrogenesis.Overall, our work demonstrates that TRAIL-producing NK cells actively contribute to liver injury and further fibrogenesis in the pathological context of GNMT deficiency, a molecular scenario characteristic of chronic human liver disease.

View Article: PubMed Central - PubMed

Affiliation: Department of Metabolomics, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Derio, Spain.

ABSTRACT
Glycine-N-methyltransferase (GNMT) is essential to preserve liver homeostasis. Cirrhotic patients show low expression of GNMT that is absent in hepatocellular carcinoma (HCC) samples. Accordingly, GNMT deficiency in mice leads to steatohepatitis, fibrosis, cirrhosis, and HCC. Lack of GNMT triggers NK cell activation in GNMT(-/-) mice and depletion of TRAIL significantly attenuates acute liver injury and inflammation in these animals. Chronic inflammation leads to fibrogenesis, further contributing to the progression of chronic liver injury regardless of the etiology. The aim of our study is to elucidate the implication of TRAIL-producing NK cells in the progression of chronic liver injury and fibrogenesis. For this we generated double TRAIL(-/-)/GNMT(-/-) mice in which we found that TRAIL deficiency efficiently protected the liver against chronic liver injury and fibrogenesis in the context of GNMT deficiency. Next, to better delineate the implication of TRAIL-producing NK cells during fibrogenesis we performed bile duct ligation (BDL) to GNMT(-/-) and TRAIL(-/-)/GNMT(-/-) mice. In GNMT(-/-) mice, exacerbated fibrogenic response after BDL concurred with NK1.1(+) cell activation. Importantly, specific inhibition of TRAIL-producing NK cells efficiently protected GNMT(-/-) mice from BDL-induced liver injury and fibrogenesis. Finally, TRAIL(-/-)/GNMT(-/-) mice showed significantly less fibrosis after BDL than GNMT(-/-) mice further underlining the relevance of the TRAIL/DR5 axis in mediating liver injury and fibrogenesis in GNMT(-/-) mice. Finally, in vivo silencing of DR5 efficiently protected GNMT(-/-) mice from BDL-liver injury and fibrogenesis, overall underscoring the key role of the TRAIL/DR5 axis in promoting fibrogenesis in the context of absence of GNMT. Overall, our work demonstrates that TRAIL-producing NK cells actively contribute to liver injury and further fibrogenesis in the pathological context of GNMT deficiency, a molecular scenario characteristic of chronic human liver disease.

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NK1.1+ cell depletion protects the liver of GNMT−/− mice against BDL-induced liver damage and fibrosis(A) Kaplan-Meier survival curve evidencing the beneficial impact of NK1.1+ cell depletion after BDL. (B) Serum transaminase and billirubin analysis, (C) H&E staining and TUNEL assay on liver sections showing lower liver injury after BDL in NK1.1/GNMT−/− mice. (D) Further quantification of necrotic areas on H&E sections and caspase-3 activity on whole liver extracts confirmed these data. (E) IHC using an αSMA Ab and Sirius Red staining and (F) further quantification evidenced reduced fibrosis in NK1.1/GNMT−/− mice. (G) qPCR analysis of αSMA, collagen1A1, TLR9 and DR5 expression. (H) WB analysis showing lower pJNK expression in NK1.1/GNMT−/− mice after BDL. n = 5–7. *p< 0.05; **p< 0.01; ***P < 0.001 (GNMT−/−vs NK1.1/GNMT−/−). Error bars represent SD.
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Figure 4: NK1.1+ cell depletion protects the liver of GNMT−/− mice against BDL-induced liver damage and fibrosis(A) Kaplan-Meier survival curve evidencing the beneficial impact of NK1.1+ cell depletion after BDL. (B) Serum transaminase and billirubin analysis, (C) H&E staining and TUNEL assay on liver sections showing lower liver injury after BDL in NK1.1/GNMT−/− mice. (D) Further quantification of necrotic areas on H&E sections and caspase-3 activity on whole liver extracts confirmed these data. (E) IHC using an αSMA Ab and Sirius Red staining and (F) further quantification evidenced reduced fibrosis in NK1.1/GNMT−/− mice. (G) qPCR analysis of αSMA, collagen1A1, TLR9 and DR5 expression. (H) WB analysis showing lower pJNK expression in NK1.1/GNMT−/− mice after BDL. n = 5–7. *p< 0.05; **p< 0.01; ***P < 0.001 (GNMT−/−vs NK1.1/GNMT−/−). Error bars represent SD.

Mentions: The important beneficial impact of NK1.1+ cell depletion was evidenced by the 100% survival of NK1.1/GNMT−/− mice after BDL, in clear contrast to the high mortality observed in GNMT−/− mice (Fig. 4A). Lower serum transaminases levels, improved liver histology showing less necrotic areas, reduced presence of TUNEL positive cells and lower caspase-3 activity confirmed the beneficial impact of NK1.1+ cell-depletion in attenuating liver injury in GNMT−/− mice after BDL (Fig. 4B–D). In accordance with less cell death, liver fibrosis was significantly attenuated in NK1.1/GNMT−/− mice as evidenced by αSMA IF, Sirius Red staining, further quantification and qPCR of αSMA and collagen 1A1 expression (Fig. 4E–G). Also, the decreased expression of TLR9 found in NK1.1/GNMT−/− mice after BDL further supported the lower activation of HSC (Fig. 4G).


TRAIL-producing NK cells contribute to liver injury and related fibrogenesis in the context of GNMT deficiency.

Fernández-Álvarez S, Gutiérrez-de Juan V, Zubiete-Franco I, Barbier-Torres L, Lahoz A, Parés A, Luka Z, Wagner C, Lu SC, Mato JM, Martínez-Chantar ML, Beraza N - Lab. Invest. (2014)

NK1.1+ cell depletion protects the liver of GNMT−/− mice against BDL-induced liver damage and fibrosis(A) Kaplan-Meier survival curve evidencing the beneficial impact of NK1.1+ cell depletion after BDL. (B) Serum transaminase and billirubin analysis, (C) H&E staining and TUNEL assay on liver sections showing lower liver injury after BDL in NK1.1/GNMT−/− mice. (D) Further quantification of necrotic areas on H&E sections and caspase-3 activity on whole liver extracts confirmed these data. (E) IHC using an αSMA Ab and Sirius Red staining and (F) further quantification evidenced reduced fibrosis in NK1.1/GNMT−/− mice. (G) qPCR analysis of αSMA, collagen1A1, TLR9 and DR5 expression. (H) WB analysis showing lower pJNK expression in NK1.1/GNMT−/− mice after BDL. n = 5–7. *p< 0.05; **p< 0.01; ***P < 0.001 (GNMT−/−vs NK1.1/GNMT−/−). Error bars represent SD.
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Related In: Results  -  Collection

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Figure 4: NK1.1+ cell depletion protects the liver of GNMT−/− mice against BDL-induced liver damage and fibrosis(A) Kaplan-Meier survival curve evidencing the beneficial impact of NK1.1+ cell depletion after BDL. (B) Serum transaminase and billirubin analysis, (C) H&E staining and TUNEL assay on liver sections showing lower liver injury after BDL in NK1.1/GNMT−/− mice. (D) Further quantification of necrotic areas on H&E sections and caspase-3 activity on whole liver extracts confirmed these data. (E) IHC using an αSMA Ab and Sirius Red staining and (F) further quantification evidenced reduced fibrosis in NK1.1/GNMT−/− mice. (G) qPCR analysis of αSMA, collagen1A1, TLR9 and DR5 expression. (H) WB analysis showing lower pJNK expression in NK1.1/GNMT−/− mice after BDL. n = 5–7. *p< 0.05; **p< 0.01; ***P < 0.001 (GNMT−/−vs NK1.1/GNMT−/−). Error bars represent SD.
Mentions: The important beneficial impact of NK1.1+ cell depletion was evidenced by the 100% survival of NK1.1/GNMT−/− mice after BDL, in clear contrast to the high mortality observed in GNMT−/− mice (Fig. 4A). Lower serum transaminases levels, improved liver histology showing less necrotic areas, reduced presence of TUNEL positive cells and lower caspase-3 activity confirmed the beneficial impact of NK1.1+ cell-depletion in attenuating liver injury in GNMT−/− mice after BDL (Fig. 4B–D). In accordance with less cell death, liver fibrosis was significantly attenuated in NK1.1/GNMT−/− mice as evidenced by αSMA IF, Sirius Red staining, further quantification and qPCR of αSMA and collagen 1A1 expression (Fig. 4E–G). Also, the decreased expression of TLR9 found in NK1.1/GNMT−/− mice after BDL further supported the lower activation of HSC (Fig. 4G).

Bottom Line: Glycine-N-methyltransferase (GNMT) is essential to preserve liver homeostasis.The aim of our study is to elucidate the implication of TRAIL-producing NK cells in the progression of chronic liver injury and fibrogenesis.Overall, our work demonstrates that TRAIL-producing NK cells actively contribute to liver injury and further fibrogenesis in the pathological context of GNMT deficiency, a molecular scenario characteristic of chronic human liver disease.

View Article: PubMed Central - PubMed

Affiliation: Department of Metabolomics, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Derio, Spain.

ABSTRACT
Glycine-N-methyltransferase (GNMT) is essential to preserve liver homeostasis. Cirrhotic patients show low expression of GNMT that is absent in hepatocellular carcinoma (HCC) samples. Accordingly, GNMT deficiency in mice leads to steatohepatitis, fibrosis, cirrhosis, and HCC. Lack of GNMT triggers NK cell activation in GNMT(-/-) mice and depletion of TRAIL significantly attenuates acute liver injury and inflammation in these animals. Chronic inflammation leads to fibrogenesis, further contributing to the progression of chronic liver injury regardless of the etiology. The aim of our study is to elucidate the implication of TRAIL-producing NK cells in the progression of chronic liver injury and fibrogenesis. For this we generated double TRAIL(-/-)/GNMT(-/-) mice in which we found that TRAIL deficiency efficiently protected the liver against chronic liver injury and fibrogenesis in the context of GNMT deficiency. Next, to better delineate the implication of TRAIL-producing NK cells during fibrogenesis we performed bile duct ligation (BDL) to GNMT(-/-) and TRAIL(-/-)/GNMT(-/-) mice. In GNMT(-/-) mice, exacerbated fibrogenic response after BDL concurred with NK1.1(+) cell activation. Importantly, specific inhibition of TRAIL-producing NK cells efficiently protected GNMT(-/-) mice from BDL-induced liver injury and fibrogenesis. Finally, TRAIL(-/-)/GNMT(-/-) mice showed significantly less fibrosis after BDL than GNMT(-/-) mice further underlining the relevance of the TRAIL/DR5 axis in mediating liver injury and fibrogenesis in GNMT(-/-) mice. Finally, in vivo silencing of DR5 efficiently protected GNMT(-/-) mice from BDL-liver injury and fibrogenesis, overall underscoring the key role of the TRAIL/DR5 axis in promoting fibrogenesis in the context of absence of GNMT. Overall, our work demonstrates that TRAIL-producing NK cells actively contribute to liver injury and further fibrogenesis in the pathological context of GNMT deficiency, a molecular scenario characteristic of chronic human liver disease.

Show MeSH
Related in: MedlinePlus