Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The . gov means it’s official. Federal government websites often end in . gov or . mil. Before sharing sensitive information, make sure you’re on a federal government site. VSports app下载.

Https

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. V体育官网.

. 2011 Apr;53(4):1342-51.
doi: 10.1002/hep.24190.

Suppression of innate immunity (natural killer cell/interferon-γ) in the advanced stages of liver fibrosis in mice

Won-Il Jeong  1 , Ogyi Park, Yang-Gun Suh, Jin-Seok Byun, So-Young Park, Earl Choi, Ja-Kyung Kim, Hyojin Ko, Hua Wang, Andrew M Miller, Bin Gao
Affiliations

Suppression of innate immunity (natural killer cell/interferon-γ) in the advanced stages of liver fibrosis in mice

Won-Il Jeong et al. Hepatology. 2011 Apr.

Abstract

Activation of innate immunity (natural killer [NK] cell/interferon-γ [IFN-γ]) has been shown to play an important role in antiviral and antitumor defenses as well as antifibrogenesis. However, little is known about the regulation of innate immunity during chronic liver injury. Here, we compared the functions of NK cells in early and advanced liver fibrosis induced by a 2-week or a 10-week carbon tetrachloride (CCl(4) ) challenge, respectively VSports手机版. Injection of polyinosinic-polycytidylic acid (poly I:C) or IFN-γ induced NK cell activation and NK cell killing of hepatic stellate cells (HSCs) in the 2-week CCl(4) model. Such activation was diminished in the 10-week CCl(4) model. Consistent with these findings, the inhibitory effect of poly I:C and IFN-γ on liver fibrosis was markedly reduced in the 10-week versus the 2-week CCl(4) model. In vitro coculture experiments demonstrated that 4-day cultured (early activated) HSCs induce NK cell activation via an NK group 2 member D/retinoic acid-induced early gene 1-dependent mechanism. Such activation was reduced when cocultured with 8-day cultured (intermediately activated) HSCs due to the production of transforming growth factor-β (TGF-β) by HSCs. Moreover, early activated HSCs were sensitive, whereas intermediately activated HSCs were resistant to IFN-γ-mediated inhibition of cell proliferation, likely due to elevated expression of suppressor of cytokine signaling 1 (SOCS1). Disruption of the SOCS1 gene restored the IFN-γ inhibition of cell proliferation in intermediately activated HSCs. Production of retinol metabolites by HSCs contributed to SOCS1 induction and subsequently inhibited IFN-γ signaling and functioning, whereas production of TGF-β by HSCs inhibited NK cell function and cytotoxicity against HSCs. .

Conclusion: The antifibrogenic effects of NK cell/IFN-γ are suppressed during advanced liver injury, which is likely due to increased production of TGF-β and expression of SOCS1 in intermediately activated HSCs V体育安卓版. .

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Poly I:C activation of liver NK cells is suppressed in 10-week CCl4 model compared with 2-week CCl4 model. Two-week or 10-week CCl4-treated mice were co-injected with poly I:C for the last 2 weeks. (A) Serum levels of IFN-γ. (B-C) Liver mononuclear cells (MNCs) and NK cells were isolated and subject to FACS analyses (B) and RT-PCR analyses (C). (D-E) Liver NK cells were used as effector cells for cytotoxicity assay against Yac-1 cells (D) or cultured day 4 HSCs (D4 HSCs) (E). (F) Liver NK cells from 2-week or 10-week CCl4-treated mouse with or without poly I:C were cultured in serum free medium for 16 h for measurement of IFN-γ levels. *P<0.05, **P<0.01.
Fig. 2
Fig. 2
IFN-γ activation of liver NK cells is diminished in 10-week CCl4 model compared with 2-week CCl4 model. Two-week or 10-week CCl4-treated mice were injected with IFN-γ for the last 2 weeks. MNCs and NK cells were isolated and subjected to FACS analyses (A) and RT-PCR analyses (B). Liver NK cells were used as effector cells for cytotoxicity assay against Yac-1 cells (C) and D4 HSCs (D). *P<0.05, **P<0.01.
Fig. 3
Fig. 3
Poly I:C or IFN-γ treatments inhibits liver fibrosis induced by 2-week CCl4 but not by 10-week CCl4 treatment. Two-week or 10-week CCl4-treated mice were co-injected with poly I:C for the last 2 weeks. (A-B) Liver tissues were collected for immunohistochemistry analyses with anti-α-SMA antibody (A), measurement of hepatic hydroxyproline content (B). (C) HSCs were isolated from the mouse liver and then subject to Western blotting. (D-E) Mice were injected with CCl4 plus IFN-γ for 2 weeks, or with CCl4 for 8 weeks and then co-treatment of CCl4 plus IFN-γ for an additional 2 or 4 weeks. Liver tissues were subsequently collected and subject to immunohistochemistry analyses with anti-α-SMA antibody (D) and measurement of hepatic hydroxyproline content (E). (F) Protein extracts from HSCs were subject to Western blotting. *P<0.05.
Fig. 4
Fig. 4
Early-activated D4 HSCs induce more NK cell activation (IFN-γ production) than intermediately-activated D8 HSCs: suppression by TGF-β. (A-C) IFN-γ levels from the supernatant of co-culture of liver NK cells and HSCs for 24 h. (A) Co-culture of NK with D0-D8 HSCs. (B) Co-culture of IFN-γ+/+ or IFN-γ−/− NK cells with IFN-γ+/+ or IFN-γ−/− D4 HSCs. (C) Co-culture of D4 HSCs with NK cells in the presence of anti-NKG2D antibody or IgG control. (D) Western blotting of cultured HSCs. (E) Activated liver NK cells from poly I:C-treated mice were used as effector cells in cytotoxicity assay against D0-D8 HSCs in the presence of anti-TGF-β antibody or IgG controls. (F) D8 HSCs were incubated with liver NK cells with or without anti-TGF-β antibody for 24 h. IFN-γ level in the supernatant was measured. *P<0.05, **P<0.01 in comparison with corresponding groups, &P<0.05 in comparison with D4 HSC.
Fig. 5
Fig. 5
D8 HSCs are resistant to IFN-γ stimulation due to induction of SOCS1. HSCs were cultured for 4 days (D4 HSCs) or 8 days (D8 HSCs). (A) D4 and D8 HSCs were treated with IFN-γ and [3H] thymidine uptake was determined. D4 and D8 HSCs was treated with IFN-γ for 30 min, followed by Western blot analysis (B) or immunocytochemistry analyses (C) with anti-pSTAT1, STAT1 or SOCS1 antibodies. In panel C, the black arrows indicate positive pSTAT1 staining in the nuclei. Open arrows indicate negative staining. (D) RT-PCR analyses of cultured HSCs. (E) Western blot analyses of D8 IFN-γ−/−SOCS1+/+ and IFN-γ−/−SOCS1−/− HSCs treated with IFN-γ for 30 min. (F) [3H] thymidine uptake analyses of D8 IFN-γ−/−SOCS1+/+ and IFN-γ−/−SOCS1−/− HSCs treated with IFN-γ. **P<0.01 compared with corresponding groups.
Fig. 6
Fig. 6
Inhibition of retinol metabolism by 4-MP blocks SOCS1 induction in intermediately-activated HSCs. (A) Intracellular concentrations of retinol and retinol metabolites from cultured HSCs treated with 4-MP. (B) RT-PCR analyses of cultured HSCs treated with 4-MP. (C) Western blot analyses of HSCs treated with 4 MP and/or IFN-γ. (D) HSCs were cultured with or without 4MP for 8 days, treated with IFN-γ and then [3H] thymidine uptake was determined. *P<0.05, **P<0.01 compared with corresponding vehicle-treated groups.
Fig. 7
Fig. 7
Retinol metabolites induce SOCS1 gene expression in HSCs, rendering HSC resistant to IFN-γ treatment. (A-B) RT-PCR analyses of SOCS1 mRNA expression from HSCs treated with retinol metabolites, RAR agonist CD437 or RXR agonist MA for 2 days. (C) HSCs were cultured with various retinol metabolits for 4 days and then cultured in serum-free medium for an additional 6 h, followed by treatment with IFN-γ for 30 min. Cell extracts were then prepared for Western blotting. (D) The densities of bands in panel C were quantified. *P<0.05, **P<0.01.
Fig. 8
Fig. 8
A double edged sword role of retinol metabolites in HSCs against NK cell activation. During HSC activation, retinols are metabolized into Rald or RA, which affect the interaction of NK and HSCs in 2 ways. (1) RA induces expression of NK cell activating ligand RAE1, which then activates NK cells through interaction with NKG2D. Activated NK cells can directly kill early-activated HSCs via releasing TRAIL or inhibit HSCs via releasing IFN-γ. IFN-γ induces cell cycle arrest and apoptosis of HSCs via activation of STAT1. (2) Retinoids (Rald and RA) can inhibit IFN-γ-mediated activation of STAT1 via induction of SOCS1, a key negative inhibitor of IFN-γ signaling, in intermediately-activated HSCs. Also, RA can activate latent TGF-β, which then inhibits NK cell activity. Therefore, retinol metabolism during HSC activation can promote NK cell activation via induction of RAE1, but can also downregulate NK cell activity via induction of TGF-β that inhibits NK cell activity, or induction of SOCS1 that inhibits IFN-γ signaling.
See this image and copyright information in PMC

"V体育ios版" References

    1. Gao B, Jeong WI, Tian Z. Liver: An organ with predominant innate immunity. Hepatology. 2008;47:729–36. - PubMed
    1. Notas G, Kisseleva T, Brenner D. NK and NKT cells in liver injury and fibrosis. Clin Immunol. 2009;130:16–26. - PubMed
    1. Muhanna N, Doron S, Amer J, Azzeh M, Mahamid M, Friedman S, Safadi R. Amelioration of hepatic fibrosis by NK cell activation. Gut. 2010 TL. in press. - PubMed
    1. Radaeva S, Sun R, Jaruga B, Nguyen VT, Tian Z, Gao B. Natural killer cells ameliorate liver fibrosis by killing activated stellate cells in NKG2D-dependent and tumor necrosis factor-related apoptosis-inducing ligand-dependent manners. Gastroenterology. 2006;130:435–52. - PubMed
    1. Melhem A, Muhanna N, Bishara A, Alvarez CE, Ilan Y, Bishara T, Horani A, Nassar M, Friedman SL, Safadi R. Anti-fibrotic activity of NK cells in experimental liver injury through killing of activated HSC. J Hepatol. 2006;45:60–71. - PubMed

Publication types

MeSH terms