Limits...
Hepatocyte-specific NEMO deletion promotes NK/NKT cell- and TRAIL-dependent liver damage.

Beraza N, Malato Y, Sander LE, Al-Masaoudi M, Freimuth J, Riethmacher D, Gores GJ, Roskams T, Liedtke C, Trautwein C - J. Exp. Med. (2009)

Bottom Line: Furthermore, hepatocyte-specific NEMO deletion strongly sensitized the liver to concanavalin A (ConA)-mediated injury.The critical role of the NK cell/TRAIL axis in NEMO(Delta hepa) livers during ConA hepatitis was further confirmed by selective NK cell depletion and adoptive transfer of TRAIL-deficient(-/-) mononuclear cells.Our results uncover an essential mechanism of NEMO-mediated protection of the liver by preventing NK cell tissue damage via TRAIL/DR5 signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine III, University Hospital (RWTH) Aachen, Aachen 5205, Germany.

ABSTRACT
Nuclear factor kappaB (NF-kappaB) is one of the main transcription factors involved in regulating apoptosis, inflammation, chronic liver disease, and cancer progression. The IKK complex mediates NF-kappaB activation and deletion of its regulatory subunit NEMO in hepatocytes (NEMO(Delta hepa)) triggers chronic inflammation and spontaneous hepatocellular carcinoma development. We show that NEMO(Delta hepa) mice were resistant to Fas-mediated apoptosis but hypersensitive to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as the result of a strong up-regulation of its receptor DR5 on hepatocytes. Additionally, natural killer (NK) cells, the main source of TRAIL, were activated in NEMO(Delta hepa) livers. Interestingly, depletion of the NK1.1(+) cells promoted a significant reduction of liver inflammation and an improvement of liver histology in NEMO(Delta hepa) mice. Furthermore, hepatocyte-specific NEMO deletion strongly sensitized the liver to concanavalin A (ConA)-mediated injury. The critical role of the NK cell/TRAIL axis in NEMO(Delta hepa) livers during ConA hepatitis was further confirmed by selective NK cell depletion and adoptive transfer of TRAIL-deficient(-/-) mononuclear cells. Our results uncover an essential mechanism of NEMO-mediated protection of the liver by preventing NK cell tissue damage via TRAIL/DR5 signaling. As this mechanism is important in human liver diseases, NEMO(Delta hepa) mice are an interesting tool to give insight into liver pathophysiology and to develop future therapeutic strategies.

Show MeSH

Related in: MedlinePlus

NEMOΔhepa mice are sensitive to low doses of TRAIL-mediated liver injury. 25 mg/kg of flagged TRAIL was administered i.v. (A) ALT serum levels were significantly elevated in NEMOΔhepa mice after TRAIL. (B–D) H&E staining (B), TUNEL assay (C), and caspase 3 activity (D) showed TRAIL-mediated liver damage and apoptosis in NEMOΔhepa mice. (E) Western blot analysis showed JNK phosphorylation. JNK1 and GAPDH were used as loading controls. (F) RT-PCR analysis of TNF mRNA and IHC showed higher expression in NEMOΔhepa mice. (G) mRNA analysis and IHC evidenced strong DR5 expression in NEMOΔhepa livers compared with NEMOf/f. Bars, 50 µm. All data are representative of three independent experiments. n = 4. **, P < 0.01; ***, P < 0.001 (NEMOf/f vs. NEMOΔhepa). §§, P < 0.01; §§§, P < 0.001 (NEMOΔhepa vs. TRAIL/NEMOΔhepa). Error bars represent SD.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2722179&req=5

fig2: NEMOΔhepa mice are sensitive to low doses of TRAIL-mediated liver injury. 25 mg/kg of flagged TRAIL was administered i.v. (A) ALT serum levels were significantly elevated in NEMOΔhepa mice after TRAIL. (B–D) H&E staining (B), TUNEL assay (C), and caspase 3 activity (D) showed TRAIL-mediated liver damage and apoptosis in NEMOΔhepa mice. (E) Western blot analysis showed JNK phosphorylation. JNK1 and GAPDH were used as loading controls. (F) RT-PCR analysis of TNF mRNA and IHC showed higher expression in NEMOΔhepa mice. (G) mRNA analysis and IHC evidenced strong DR5 expression in NEMOΔhepa livers compared with NEMOf/f. Bars, 50 µm. All data are representative of three independent experiments. n = 4. **, P < 0.01; ***, P < 0.001 (NEMOf/f vs. NEMOΔhepa). §§, P < 0.01; §§§, P < 0.001 (NEMOΔhepa vs. TRAIL/NEMOΔhepa). Error bars represent SD.

Mentions: Thus, we next investigated the potential implication of TRAIL in the initiation and progression of chronic liver damage in our NEMO-deficient mice. As expected, low doses of TRAIL had no effect on NEMOf/f mice, as ALT levels and liver architecture remained unaffected (Fig. 2, A and B). In clear contrast, TRAIL had a strong impact on NEMOΔhepa mice, as a significant rise in serum ALT and massive liver damage, indicated by profuse PMN infiltration, necrosis, and apoptosis, were observed (Fig. 2, A and B). TUNEL assay and caspase 3 activity confirmed the severity of TRAIL-mediated apoptosis on NEMOΔhepa mice (Fig. 2, C and D). Previous work indicated that TRAIL induced JNK activation, leading to cellular apoptosis (Herr et al., 1999). Accordingly, we found that TRAIL promoted strong JNK activation in NEMOΔhepa livers, whereas it remained inactive in NEMOf/f mice (Fig. 2 E). Moreover, TRAIL administration promoted a significant induction of TNF in NEMOΔhepa mice that was confirmed by IHC, uncovering the Kupffer cells as its main source (Fig. 2 F). These results suggest that hepatocyte-NEMO deletion promotes hypersensitivity to TRAIL-mediated apoptosis; hence, we next attempted to elucidate the potential mechanisms underlying this effect.


Hepatocyte-specific NEMO deletion promotes NK/NKT cell- and TRAIL-dependent liver damage.

Beraza N, Malato Y, Sander LE, Al-Masaoudi M, Freimuth J, Riethmacher D, Gores GJ, Roskams T, Liedtke C, Trautwein C - J. Exp. Med. (2009)

NEMOΔhepa mice are sensitive to low doses of TRAIL-mediated liver injury. 25 mg/kg of flagged TRAIL was administered i.v. (A) ALT serum levels were significantly elevated in NEMOΔhepa mice after TRAIL. (B–D) H&E staining (B), TUNEL assay (C), and caspase 3 activity (D) showed TRAIL-mediated liver damage and apoptosis in NEMOΔhepa mice. (E) Western blot analysis showed JNK phosphorylation. JNK1 and GAPDH were used as loading controls. (F) RT-PCR analysis of TNF mRNA and IHC showed higher expression in NEMOΔhepa mice. (G) mRNA analysis and IHC evidenced strong DR5 expression in NEMOΔhepa livers compared with NEMOf/f. Bars, 50 µm. All data are representative of three independent experiments. n = 4. **, P < 0.01; ***, P < 0.001 (NEMOf/f vs. NEMOΔhepa). §§, P < 0.01; §§§, P < 0.001 (NEMOΔhepa vs. TRAIL/NEMOΔhepa). Error bars represent SD.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2722179&req=5

fig2: NEMOΔhepa mice are sensitive to low doses of TRAIL-mediated liver injury. 25 mg/kg of flagged TRAIL was administered i.v. (A) ALT serum levels were significantly elevated in NEMOΔhepa mice after TRAIL. (B–D) H&E staining (B), TUNEL assay (C), and caspase 3 activity (D) showed TRAIL-mediated liver damage and apoptosis in NEMOΔhepa mice. (E) Western blot analysis showed JNK phosphorylation. JNK1 and GAPDH were used as loading controls. (F) RT-PCR analysis of TNF mRNA and IHC showed higher expression in NEMOΔhepa mice. (G) mRNA analysis and IHC evidenced strong DR5 expression in NEMOΔhepa livers compared with NEMOf/f. Bars, 50 µm. All data are representative of three independent experiments. n = 4. **, P < 0.01; ***, P < 0.001 (NEMOf/f vs. NEMOΔhepa). §§, P < 0.01; §§§, P < 0.001 (NEMOΔhepa vs. TRAIL/NEMOΔhepa). Error bars represent SD.
Mentions: Thus, we next investigated the potential implication of TRAIL in the initiation and progression of chronic liver damage in our NEMO-deficient mice. As expected, low doses of TRAIL had no effect on NEMOf/f mice, as ALT levels and liver architecture remained unaffected (Fig. 2, A and B). In clear contrast, TRAIL had a strong impact on NEMOΔhepa mice, as a significant rise in serum ALT and massive liver damage, indicated by profuse PMN infiltration, necrosis, and apoptosis, were observed (Fig. 2, A and B). TUNEL assay and caspase 3 activity confirmed the severity of TRAIL-mediated apoptosis on NEMOΔhepa mice (Fig. 2, C and D). Previous work indicated that TRAIL induced JNK activation, leading to cellular apoptosis (Herr et al., 1999). Accordingly, we found that TRAIL promoted strong JNK activation in NEMOΔhepa livers, whereas it remained inactive in NEMOf/f mice (Fig. 2 E). Moreover, TRAIL administration promoted a significant induction of TNF in NEMOΔhepa mice that was confirmed by IHC, uncovering the Kupffer cells as its main source (Fig. 2 F). These results suggest that hepatocyte-NEMO deletion promotes hypersensitivity to TRAIL-mediated apoptosis; hence, we next attempted to elucidate the potential mechanisms underlying this effect.

Bottom Line: Furthermore, hepatocyte-specific NEMO deletion strongly sensitized the liver to concanavalin A (ConA)-mediated injury.The critical role of the NK cell/TRAIL axis in NEMO(Delta hepa) livers during ConA hepatitis was further confirmed by selective NK cell depletion and adoptive transfer of TRAIL-deficient(-/-) mononuclear cells.Our results uncover an essential mechanism of NEMO-mediated protection of the liver by preventing NK cell tissue damage via TRAIL/DR5 signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine III, University Hospital (RWTH) Aachen, Aachen 5205, Germany.

ABSTRACT
Nuclear factor kappaB (NF-kappaB) is one of the main transcription factors involved in regulating apoptosis, inflammation, chronic liver disease, and cancer progression. The IKK complex mediates NF-kappaB activation and deletion of its regulatory subunit NEMO in hepatocytes (NEMO(Delta hepa)) triggers chronic inflammation and spontaneous hepatocellular carcinoma development. We show that NEMO(Delta hepa) mice were resistant to Fas-mediated apoptosis but hypersensitive to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as the result of a strong up-regulation of its receptor DR5 on hepatocytes. Additionally, natural killer (NK) cells, the main source of TRAIL, were activated in NEMO(Delta hepa) livers. Interestingly, depletion of the NK1.1(+) cells promoted a significant reduction of liver inflammation and an improvement of liver histology in NEMO(Delta hepa) mice. Furthermore, hepatocyte-specific NEMO deletion strongly sensitized the liver to concanavalin A (ConA)-mediated injury. The critical role of the NK cell/TRAIL axis in NEMO(Delta hepa) livers during ConA hepatitis was further confirmed by selective NK cell depletion and adoptive transfer of TRAIL-deficient(-/-) mononuclear cells. Our results uncover an essential mechanism of NEMO-mediated protection of the liver by preventing NK cell tissue damage via TRAIL/DR5 signaling. As this mechanism is important in human liver diseases, NEMO(Delta hepa) mice are an interesting tool to give insight into liver pathophysiology and to develop future therapeutic strategies.

Show MeSH
Related in: MedlinePlus