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Yu L, Yan J, Zhan Y, Li A, Zhu L, Qian J, Zhou F, Lu X, Fan X. Single-cell RNA sequencing reveals the dynamics of hepatic non-parenchymal cells in autoprotection against acetaminophen-induced hepatotoxicity. J Pharm Anal 2023; 13:926-941. [PMID: 37719199 PMCID: PMC10499594 DOI: 10.1016/j.jpha.2023.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 05/05/2023] [Accepted: 05/08/2023] [Indexed: 09/19/2023] Open
Abstract
Gaining a better understanding of autoprotection against drug-induced liver injury (DILI) may provide new strategies for its prevention and therapy. However, little is known about the underlying mechanisms of this phenomenon. We used single-cell RNA sequencing to characterize the dynamics and functions of hepatic non-parenchymal cells (NPCs) in autoprotection against DILI, using acetaminophen (APAP) as a model drug. Autoprotection was modeled through pretreatment with a mildly hepatotoxic dose of APAP in mice, followed by a higher dose in a secondary challenge. NPC subsets and dynamic changes were identified in the APAP (hepatotoxicity-sensitive) and APAP-resistant (hepatotoxicity-resistant) groups. A chemokine (C-C motif) ligand 2+ endothelial cell subset almost disappeared in the APAP-resistant group, and an R-spondin 3+ endothelial cell subset promoted hepatocyte proliferation and played an important role in APAP autoprotection. Moreover, the dendritic cell subset DC-3 may protect the liver from APAP hepatotoxicity by inducing low reactivity and suppressing the autoimmune response and occurrence of inflammation. DC-3 cells also promoted angiogenesis through crosstalk with endothelial cells via vascular endothelial growth factor-associated ligand-receptor pairs and facilitated liver tissue repair in the APAP-resistant group. In addition, the natural killer cell subsets NK-3 and NK-4 and the Sca-1-CD62L+ natural killer T cell subset may promote autoprotection through interferon-γ-dependent pathways. Furthermore, macrophage and neutrophil subpopulations with anti-inflammatory phenotypes promoted tolerance to APAP hepatotoxicity. Overall, this study reveals the dynamics of NPCs in the resistance to APAP hepatotoxicity and provides novel insights into the mechanism of autoprotection against DILI at a high resolution.
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Affiliation(s)
- Lingqi Yu
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
- Future Health Laboratory, Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing, Zhejiang, 314100, China
| | - Jun Yan
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Yingqi Zhan
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Anyao Li
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
- Future Health Laboratory, Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing, Zhejiang, 314100, China
| | - Lidan Zhu
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Jingyang Qian
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
- Future Health Laboratory, Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing, Zhejiang, 314100, China
| | - Fanfan Zhou
- School of Pharmacy, The University of Sydney, Sydney, 2006, Australia
| | - Xiaoyan Lu
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
- Future Health Laboratory, Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing, Zhejiang, 314100, China
- Innovation Center in Zhejiang University, State Key Laboratory of Component-Based Chinese Medicine, Hangzhou 310058, China
- Jinhua Institute of Zhejiang University, Jinhua, Zhejiang, 321016, China
- Hangzhou Institute of Innovative Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Xiaohui Fan
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
- Future Health Laboratory, Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing, Zhejiang, 314100, China
- Innovation Center in Zhejiang University, State Key Laboratory of Component-Based Chinese Medicine, Hangzhou 310058, China
- Jinhua Institute of Zhejiang University, Jinhua, Zhejiang, 321016, China
- Engineering Research Center of Innovative Anticancer Drugs, Ministry of Education, Harbin, 150023, China
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2
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Hosseinzadeh F, Ai J, Hajifathali A, Muhammadnejad S, Ebrahimi-Barough S, Seyhoun I, Komeili Movahed T, Shirian S, Hosseinzadeh F, Ahmadpour S, Alijani M, Verdi J. The effects of Sorafenib and Natural killer cell co-injection in combinational treatment of hepatocellular carcinoma; an in vivo approach. Pharmacol Rep 2022; 74:379-391. [PMID: 35089543 DOI: 10.1007/s43440-021-00335-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/16/2021] [Accepted: 10/19/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Natural killer cells (NKC) and Sorafenib (Sor) are two important agents for the treatment of hepatocellular carcinoma (HCC). Over the past decade, the interaction of Sor and NKC against HCC has been widely challenging. This study aimed to assess the efficacy of NKC & Sor for the treatment of HCC in vivo. METHODS Subcutaneous xenograft models of HCC were established in nude mice. For safety assessment of treatment, the kidney and liver functions were analyzed. Paraffin embedded tumor sections were histopathologically studied and immunohistochemistry (IHC) tests were done to evaluate the angiogenesis (CD34) and proliferation (Ki67) indexes. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to identify the tumor cells undergoing apoptosis. The serum levels of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were measured by enzyme-linked immunosorbent assay (ELISA) and expression levels of major inflammatory cytokines and cytoplasmic granules in xenograft HCC were quantified using real-time PCR. RESULTS NKC & Sor significantly inhibited necrosis and apoptosis in tumor cells and increased angiogenesis and proliferation of HCC compared to the monotherapy of NKC or Sor alone. The serum levels of TNF-α, IFN-γ as well as the expression levels of TNF-α, IFN-γ, interleukins (ILs)-1, 6, 10, granzyme-B and perforin in the xenograft HCC tissues of the treated mice with NKC & Sor were significantly lower than those of treated with NKC or Sor alone. CONCLUSION Therapy with the specific dosage of NKC & Sor could not inhibit the HCC xenograft growth rate through a synergistic effect in a mouse model of HCC.
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Affiliation(s)
- Faezeh Hosseinzadeh
- Department of Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran. .,Department of Tissue Engineering, Qom University of Medical Sciences, Qom, Iran. .,Cellular and Molecular Research Center, Qom University of Medical Sciences, Qom, Iran.
| | - Jafar Ai
- Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Hajifathali
- Hematopoietic Stem Cell Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Samad Muhammadnejad
- Gene Therapy Research Center, Digestive Diseases Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Somayeh Ebrahimi-Barough
- Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Iman Seyhoun
- Department of Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Sadegh Shirian
- Department of Pathology, School of Veterinary Medicine, Shahrekord University, Shahrekord, Iran.,Shiraz Molecular Pathology Research Center, Dr. Daneshbod Path Lab, Shiraz, Iran
| | | | - Sajjad Ahmadpour
- Gastroenterology and Hepatology Diseases Research Center, Qom University of Medical Sciences, Qom, Iran
| | - Mohammadreza Alijani
- Department of Pathology, School of Veterinary Medicine, Shahrekord University, Shahrekord, Iran.,Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Javad Verdi
- Department of Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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Nabekura T, Riggan L, Hildreth AD, O’Sullivan TE, Shibuya A. Type 1 Innate Lymphoid Cells Protect Mice from Acute Liver Injury via Interferon-γ Secretion for Upregulating Bcl-xL Expression in Hepatocytes. Immunity 2020; 52:96-108.e9. [PMID: 31810881 PMCID: PMC8108607 DOI: 10.1016/j.immuni.2019.11.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 10/01/2019] [Accepted: 11/07/2019] [Indexed: 01/27/2023]
Abstract
Although type 1 innate lymphoid cells (ILC1s) have been originally found as liver-resident ILCs, their pathophysiological role in the liver remains poorly investigated. Here, we demonstrated that carbon tetrachloride (CCl4) injection into mice activated ILC1s, but not natural killer (NK) cells, in the liver. Activated ILC1s produced interferon-γ (IFN-γ) and protected mice from CCl4-induced acute liver injury. IFN-γ released from activated ILC1s promoted the survival of hepatocytes through upregulation of Bcl-xL. An activating NK receptor, DNAM-1, was required for the optimal activation and IFN-γ production of liver ILC1s. Extracellular adenosine triphosphate accelerated interleukin-12-driven IFN-γ production by liver ILC1s. These findings suggest that ILC1s are critical for tissue protection during acute liver injury.
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Affiliation(s)
- Tsukasa Nabekura
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.,Department of Immunology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.,R&D Center for Innovative Drug Discovery, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Luke Riggan
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Andrew D. Hildreth
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Timothy E. O’Sullivan
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.,Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Akira Shibuya
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan; Department of Immunology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan; R&D Center for Innovative Drug Discovery, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
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Zhao ZB, Lu FT, Ma HD, Wang YH, Yang W, Long J, Miao Q, Zhang W, Tian Z, Ridgway WM, Cao J, Gershwin ME, Lian ZX. Liver-resident NK cells suppress autoimmune cholangitis and limit the proliferation of CD4 + T cells. Cell Mol Immunol 2020; 17:178-89. [PMID: 30874628 DOI: 10.1038/s41423-019-0199-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 01/01/2019] [Indexed: 12/13/2022] Open
Abstract
Liver-resident NK cells are distinct from conventional NK cells and play an important role in the maintenance of liver homeostasis. How liver-resident NK cells participate in autoimmune cholangitis remains unclear. Here, we extensively investigated the impact of NK cells in the pathogenesis of autoimmune cholangitis utilizing the well-established dnTGFβRII cholangitis model, NK cell-deficient (Nfil3-/-) mice, adoptive transfer and in vivo antibody-mediated NK cell depletion. Our data demonstrated that disease progression was associated with a significantly reduced frequency of hepatic NK cells. Depletion of NK cells resulted in exacerbated autoimmune cholangitis in dnTGFβRII mice. We further confirmed that the DX5-CD11chi liver-resident NK cell subset colocalized with CD4+ T cells and inhibited CD4+ T cell proliferation. Gene expression microarray analysis demonstrated that liver-resident NK cells had a distinct gene expression pattern consisting of the increased expression of genes involved in negative regulatory functions in the context of the inflammatory microenvironment.
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Lin EY, Chagnaadorj A, Huang SJ, Wang CC, Chiang YH, Cheng CW. Hepatoprotective Activity of the Ethanolic Extract of Polygonum multiflorum Thunb. against Oxidative Stress-Induced Liver Injury. Evid Based Complement Alternat Med 2018; 2018:4130307. [PMID: 30416531 DOI: 10.1155/2018/4130307] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 09/18/2018] [Accepted: 09/30/2018] [Indexed: 12/15/2022]
Abstract
Oxidative stress is an important pathological mechanism in various liver diseases. Polygonum multiflorum Thunb. (PM) can be used for the treatment of diseases associated with aging, hyperlipidemia, and oxidative stress in traditional Chinese medicine. In this study, we examined the hepatoprotective effects of the ethanolic extract of PM (PME) in in vitro and in vivo models. The PME induced expression of antioxidant-response-element- (ARE-) related genes in HepG2 cells showed a dose-dependent manner. Pretreatment of HepG2 cell with PME suppressed H2O2- and acetaminophen- (APAP-) induced cellular reactive oxygen species (ROS) generation and cytotoxicity. In APAP-induced mouse liver injury, pretreatment with PME also showed ability to increase the survival rate and reduce the severity of liver injury. Treatment with PME attenuated bile duct ligation-induced extrahepatic cholestatic liver injury and further increased multidrug resistance protein 4 (MRP4) and reduced organic anion-transporting polypeptide (OATP) expression. Furthermore, increased nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2) was observed after treatment with PME in both in vivo models. In conclusion, the current study showed the hepatoprotective activity of PME by regulating the redox state in liver injury through Nrf2 activation and controlling hepatic bile acid homeostasis in obstructive cholestasis, through bile acid transporter expression modulation.
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6
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Wammers M, Schupp AK, Bode JG, Ehlting C, Wolf S, Deenen R, Köhrer K, Häussinger D, Graf D. Reprogramming of pro-inflammatory human macrophages to an anti-inflammatory phenotype by bile acids. Sci Rep 2018; 8:255. [PMID: 29321478 DOI: 10.1038/s41598-017-18305-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 12/04/2017] [Indexed: 12/11/2022] Open
Abstract
Cholestasis is caused by autoimmune reactions, drug-induced hepatotoxicity, viral infections of the liver and the obstruction of bile ducts by tumours or gallstones. Cholestatic conditions are associated with impaired innate and adaptive immunity, including alterations of the cellular functions of monocytes, macrophages, NK cells and T-cells. Bile acids act as signalling molecules, affecting lipopolysaccharide (LPS)-induced cytokine expression in primary human macrophages. The present manuscript investigates the impact of bile acids, such as taurolithocholic acid (TLC), on the transcriptome of human macrophages in the presence or absence of LPS. While TLC itself has almost no effect on gene expression under control conditions, this compound modulates the expression of 202 out of 865 transcripts in the presence of LPS. Interestingly, pathway analysis revealed that TLC specifically supressed the expression of genes involved in mediating pro-inflammatory effects, phagocytosis, interactions with pathogens and autophagy as well as the recruitment of immune cells, such as NK cells, neutrophils and T cells. These data indicate a broad influence of bile acids on inflammatory responses and immune functions in macrophages. These findings may contribute to the clinical observation that patients with cholestasis present a lack of response to bacterial or viral infections.
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7
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Cui K, Yan G, Zheng X, Bai L, Wei H, Sun R, Tian Z. Suppression of Natural Killer Cell Activity by Regulatory NKT10 Cells Aggravates Alcoholic Hepatosteatosis. Front Immunol 2017; 8:1414. [PMID: 29163491 PMCID: PMC5670109 DOI: 10.3389/fimmu.2017.01414] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 10/12/2017] [Indexed: 12/28/2022] Open
Abstract
We and others have found that the functions of hepatic natural killer (NK) cells are inhibited but invariant NKT (iNKT) cells become activated after alcohol drinking, leaving a possibility that there exists interplay between NK cells and iNKT cells during alcoholic liver disease. Here, in a chronic plus single-binge ethanol consumption mouse model, we observed that NK cells and interferon-γ (IFN-γ) protected against ethanol-induced liver steatosis, as both wild-type (WT) mice treated with anti-asialo GM1 antibody and IFN-γ-deficient GKO mice developed more severe alcoholic fatty livers. As expected, IFN-γ could directly downregulate lipogenesis in primary hepatocytes in vitro. On the contrary, iNKT cell-deficient Jα18-/- or interleukin-10 (IL-10)-/- mice showed fewer alcoholic steatosis, along with the recovered number and IFN-γ release of hepatic NK cells, and exogenous IL-10 injection was sufficient to compensate for iNKT cell deficiency. Furthermore, NK cell depletion in Jα18-/- or IL-10-/- mice caused more severe hepatosteatosis, implying NK cells are the direct effector cells to inhibit liver steatosis. Importantly, adoptive transfer of iNKT cells purified from normal but not IL-10-/- mice resulted in suppression of the number and functions of NK cells and aggravated alcoholic liver injury in Jα18-/- mice, indicating that IL-10-producing iNKT (NKT10) cells are the regulators on NK cells. Conclusion: Ethanol exposure-triggered NKT10 cells antagonize the protective roles of NK cells in alcoholic hepatosteatosis.
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Affiliation(s)
- Kele Cui
- The CAS Key Laboratory of Innate Immunity and Chronic Disease and Institute of Immunology, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei, China.,Anhui Province Hospital Affiliated Anhui Medical University, Hefei, China
| | - Guoxiu Yan
- The CAS Key Laboratory of Innate Immunity and Chronic Disease and Institute of Immunology, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei, China
| | - Xiaodong Zheng
- The CAS Key Laboratory of Innate Immunity and Chronic Disease and Institute of Immunology, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei, China
| | - Li Bai
- The CAS Key Laboratory of Innate Immunity and Chronic Disease and Institute of Immunology, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei, China
| | - Haiming Wei
- The CAS Key Laboratory of Innate Immunity and Chronic Disease and Institute of Immunology, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei, China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Rui Sun
- The CAS Key Laboratory of Innate Immunity and Chronic Disease and Institute of Immunology, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei, China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Zhigang Tian
- The CAS Key Laboratory of Innate Immunity and Chronic Disease and Institute of Immunology, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei, China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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8
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Abstract
Bile acids are synthesized in the liver and are the major component in bile. Impaired bile flow leads to cholestasis that is characterized by elevated levels of bile acid in the liver and serum, followed by hepatocyte and biliary injury. Although the causes of cholestasis have been extensively studied, the molecular mechanisms as to how bile acids initiate liver injury remain controversial. In this chapter, we summarize recent advances in the pathogenesis of bile acid induced liver injury. These include bile acid signaling pathways in hepatocytes as well as the response of cholangiocytes and innate immune cells in the liver in both patients with cholestasis and cholestatic animal models. We focus on how bile acids trigger the production of molecular mediators of neutrophil recruitment and the role of the inflammatory response in this pathological process. These advances point to a number of novel targets where drugs might be judged to be effective therapies for cholestatic liver injury.
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Affiliation(s)
- Man Li
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shi-Ying Cai
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - James L Boyer
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA.
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9
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Li M, Cai SY, Boyer JL. Mechanisms of bile acid mediated inflammation in the liver. Mol Aspects Med 2017; 56:45-53. [PMID: 28606651 DOI: 10.1016/j.mam.2017.06.001] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 05/26/2017] [Accepted: 06/07/2017] [Indexed: 02/07/2023]
Abstract
Bile acids are synthesized in the liver and are the major component in bile. Impaired bile flow leads to cholestasis that is characterized by elevated levels of bile acid in the liver and serum, followed by hepatocyte and biliary injury. Although the causes of cholestasis have been extensively studied, the molecular mechanisms as to how bile acids initiate liver injury remain controversial. In this chapter, we summarize recent advances in the pathogenesis of bile acid induced liver injury. These include bile acid signaling pathways in hepatocytes as well as the response of cholangiocytes and innate immune cells in the liver in both patients with cholestasis and cholestatic animal models. We focus on how bile acids trigger the production of molecular mediators of neutrophil recruitment and the role of the inflammatory response in this pathological process. These advances point to a number of novel targets where drugs might be judged to be effective therapies for cholestatic liver injury.
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Affiliation(s)
- Man Li
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shi-Ying Cai
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA
| | - James L Boyer
- The Liver Center, Yale University School of Medicine, New Haven, CT 06510, USA.
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10
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Goh CC, Roggerson KM, Lee HC, Golden-Mason L, Rosen HR, Hahn YS. Hepatitis C Virus-Induced Myeloid-Derived Suppressor Cells Suppress NK Cell IFN-γ Production by Altering Cellular Metabolism via Arginase-1. J Immunol 2016; 196:2283-92. [PMID: 26826241 DOI: 10.4049/jimmunol.1501881] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/28/2015] [Indexed: 12/21/2022]
Abstract
The hepatitis C virus (HCV) infects ∼ 200 million people worldwide. The majority of infected individuals develop persistent infection, resulting in chronic inflammation and liver disease, including cirrhosis and hepatocellular carcinoma. The ability of HCV to establish persistent infection is partly due to its ability to evade the immune response through multiple mechanisms, including suppression of NK cells. NK cells control HCV replication during the early phase of infection and regulate the progression to chronic disease. In particular, IFN-γ produced by NK cells limits viral replication in hepatocytes and is important for the initiation of adaptive immune responses. However, NK cell function is significantly impaired in chronic HCV patients. The cellular and molecular mechanisms responsible for impaired NK cell function in HCV infection are not well defined. In this study, we analyzed the interaction of human NK cells with CD33(+) PBMCs that were exposed to HCV. We found that NK cells cocultured with HCV-conditioned CD33(+) PBMCs produced lower amounts of IFN-γ, with no effect on granzyme B production or cell viability. Importantly, this suppression of NK cell-derived IFN-γ production was mediated by CD33(+)CD11b(lo)HLA-DR(lo) myeloid-derived suppressor cells (MDSCs) via an arginase-1-dependent inhibition of mammalian target of rapamycin activation. Suppression of IFN-γ production was reversed by l-arginine supplementation, consistent with increased MDSC arginase-1 activity. These novel results identify the induction of MDSCs in HCV infection as a potent immune evasion strategy that suppresses antiviral NK cell responses, further indicating that blockade of MDSCs may be a potential therapeutic approach to ameliorate chronic viral infections in the liver.
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Affiliation(s)
- Celeste C Goh
- Beirne Carter Center for Immunology Research, University of Virginia School of Medicine, Charlottesville, VA 22908; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Krystal M Roggerson
- Beirne Carter Center for Immunology Research, University of Virginia School of Medicine, Charlottesville, VA 22908; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Hai-Chon Lee
- Beirne Carter Center for Immunology Research, University of Virginia School of Medicine, Charlottesville, VA 22908; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908; Wide River Institute of Immunology, Seoul National University, Gangwon 25159, Korea; and
| | - Lucy Golden-Mason
- Department of Gastroenterology, University of Colorado Health Sciences Center, Aurora, CO 80045
| | - Hugo R Rosen
- Department of Gastroenterology, University of Colorado Health Sciences Center, Aurora, CO 80045
| | - Young S Hahn
- Beirne Carter Center for Immunology Research, University of Virginia School of Medicine, Charlottesville, VA 22908; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908;
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11
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Abstract
INTRODUCTION Cholestasis is a reduction in bile flow that occurs during numerous pathologies. Blockage of the biliary tracts results in hepatic accumulation of bile acids or their conjugate bile salts. The molecular mechanisms behind liver injury associated with cholestasis are extensively studied, but not well understood. Multiple models of obstructive cholestasis result in a significant inflammatory infiltrate at the sites of necrosis that characterize the injury. AREAS COVERED This review will focus on direct bile acid toxicity during cholestasis, bile acid signaling processes and on the development and continuation of inflammation during cholestasis, with a focus on novel proposed molecular mediators of neutrophil recruitment. While significant progress has been made on these molecular mechanisms, a continued focus on how cholestasis and the innate immune system interact is necessary to discover targetable therapeutics that might protect the liver while leaving global immunity intact. EXPERT OPINION While bile acid toxicity likely occurs in humans and other mammals when toxic bile acids accumulate, persistent inflammation is likely responsible for continued liver injury during obstructive cholestasis. Targeting molecular mediators of inflammation may help prevent liver injury during acute cholestasis both in murine models and human patients.
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Affiliation(s)
- Benjamin L Woolbright
- a Department of Pharmacology , Toxicology & Therapeutics, University of Kansas Medical Center , 3901 Rainbow Blvd, MS 1018, Kansas City , KS , 66160 USA
| | - Hartmut Jaeschke
- a Department of Pharmacology , Toxicology & Therapeutics, University of Kansas Medical Center , 3901 Rainbow Blvd, MS 1018, Kansas City , KS , 66160 USA
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12
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D'Mello C, Swain MG. Liver-brain interactions in inflammatory liver diseases: implications for fatigue and mood disorders. Brain Behav Immun 2014; 35:9-20. [PMID: 24140301 DOI: 10.1016/j.bbi.2013.10.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/28/2013] [Accepted: 10/09/2013] [Indexed: 12/15/2022] Open
Abstract
Chronic inflammatory liver diseases are often accompanied by behavior alterations including fatigue, mood disorders, cognitive dysfunction and sleep disturbances. These altered behaviors can adversely affect patient quality of life. The communication pathways between the inflamed liver and the brain that mediate changes in central neural activity leading to behavior alterations during liver inflammation are poorly understood. Neural and humoral communication pathways have been most commonly implicated as driving peripheral inflammation to brain signaling. Classically, the cytokines TNFα, IL-1β and IL-6 have received the greatest scientific attention as potential mediators of this communication pathway. In mice with liver inflammation we have identified a novel immune-mediated liver-to-brain communication pathway whereby CCR2(+) monocytes found within the peripheral circulation transmigrate into the brain parenchyma in response to MCP-1/CCL2 expressing activated microglia. Inhibition of cerebral monocyte infiltration in these mice significantly improved liver inflammation associated sickness behaviors. Importantly, in recent work we have found that at an earlier time point, when cerebral monocyte infiltration is not evident in mice with liver inflammation, increased monocyte:cerebral endothelial cell adhesive interactions are observed using intravital microscopy of the brain. These monocyte:cerebral endothelial cell adhesive interactions are P-selectin mediated, and inhibition of these interactions attenuated microglial activation and sickness behavior development. Delineating the pathways that the periphery uses to communicate with the brain during inflammatory liver diseases, and the central neurotransmitter systems that are altered through these communication pathways (e.g., serotonin, corticotrophin releasing hormone) to give rise to liver inflammation-associated sickness behaviors, will allow for the identification of novel therapeutic targets to decrease the burden of debilitating symptoms in these patients.
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Duwaerts CC, Sun EP, Cheng CW, van Rooijen N, Gregory SH. Cross-activating invariant NKT cells and kupffer cells suppress cholestatic liver injury in a mouse model of biliary obstruction. PLoS One 2013; 8:e79702. [PMID: 24260285 PMCID: PMC3829879 DOI: 10.1371/journal.pone.0079702] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 10/04/2013] [Indexed: 12/15/2022] Open
Abstract
Both Kupffer cells and invariant natural killer T (iNKT) cells suppress neutrophil-dependent liver injury in a mouse model of biliary obstruction. We hypothesize that these roles are interdependent and require iNKT cell-Kupffer cell cross-activation. Female, wild-type and iNKT cell-deficient C57Bl/6 mice were injected with magnetic beads 3 days prior to bile duct ligation (BDL) in order to facilitate subsequent Kupffer cell isolation. On day three post-BDL, the animals were euthanized and the livers dissected. Necrosis was scored; Kupffer cells were isolated and cell surface marker expression (flow cytometry), mRNA expression (qtPCR), nitric oxide (NO.) production (Griess reaction), and protein secretion (cytometric bead-array or ELISAs) were determined. To address the potential role of NO. in suppressing neutrophil accumulation, a group of WT mice received 1400W, a specific inducible nitric oxide synthase (iNOS) inhibitor, prior to BDL. To clarify the mechanisms underlying Kupffer cell-iNKT cell cross-activation, WT animals were administered anti-IFN-γ or anti-lymphocyte function-associated antigen (LFA)-1 antibody prior to BDL. Compared to their WT counterparts, Kupffer cells obtained from BDL iNKT cell-deficient mice expressed lower iNOS mRNA levels, produced less NO., and secreted more neutrophil chemoattractants. Both iNOS inhibition and IFN-γ neutralization increased neutrophil accumulation in the livers of BDL WT mice. Anti-LFA-1 pre-treatment reduced iNKT cell accumulation in these same animals. These data indicate that the LFA-1-dependent cross-activation of iNKT cells and Kupffer cells inhibits neutrophil accumulation and cholestatic liver injury.
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Affiliation(s)
- Caroline C. Duwaerts
- Department of Medicine, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- * E-mail:
| | - Eric P. Sun
- Department of Medicine, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Chao-Wen Cheng
- Department of Medicine, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Nico van Rooijen
- Department of Cell Biology, Vrije Universiteit, Amsterdam, The Netherlands
| | - Stephen H. Gregory
- Department of Medicine, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
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Deniz GY, Geyikoğlu F, Türkez H, Bakır TÖ, Çolak S, Aslan A. The biochemical and histological effects of lichens in normal and diabetic rats. Toxicol Ind Health 2013; 32:601-13. [DOI: 10.1177/0748233713506769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Oxidative stress plays an important role in causing diabetes; however, no studies have thoroughly reported on the toxic and beneficial effects of lichen extracts in patients with diabetes mellitus (DM). This study covers a previously unrecognized effect of two well-known lichen species Cetraria islandica and Pseudevernia furfuracae in streptozotocin (STZ)-induced diabetes. In experimental design, control or diabetic rats were either untreated or treated with aqueous lichen extracts (250–500 mg/kg /day) for 2 weeks starting at 72 h after STZ injection. On day 14, animals were anaesthetized, and metabolic and biochemical parameters were appreciated between control and treatment groups. The histopathology of liver was examined using three different staining methods: hematoxylin–eosin (H&E), periodic acid Schiff (PAS), and reticulin and Sudan Black B. Our experimental data showed that increasing doses of C. islandica and P. furfuracae alone did not have any detrimental effects on studied parameters and the malondialdehyde level of liver. C. islandica extract showed positive results for antioxidant capacity compared to doses of P. furfuracae extract. However, the protective effect of C. islandica extract on diabetes-induced disorders and hepatic damages is still unclear. Moreover, unfortunately, animals subjected to DM therapy did not benefit from the usage of increasing lichen doses due to their unchanged antioxidant activity in tissues. The results obtained in present study suggested that C. islandica and P. furfuracae is safe but the power of these is limited because of intensive oxidative stress in liver of type 1 diabetic rats. It is also implied that C. islandica extract is especially suitable for different administration routes in DM animals.
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Affiliation(s)
| | | | - Hasan Türkez
- Department of Molecular Biology and Genetics, Erzurum Technical University, Erzurum, Turkey
| | | | - Suat Çolak
- Department of Biology, Artvin Coruh University, Artvin, Turkey
| | - Ali Aslan
- Department of Biology, Kazim Karabekir Education Faculty, Ataturk University, Erzurum, Turkey
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Licata LA, Nguyen CT, Burga RA, Falanga V, Espat NJ, Ayala A, Thorn M, Junghans RP, Katz SC. Biliary obstruction results in PD-1-dependent liver T cell dysfunction and acute inflammation mediated by Th17 cells and neutrophils. J Leukoc Biol 2013; 94:813-23. [PMID: 23883516 DOI: 10.1189/jlb.0313137] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Biliary obstruction is a common clinical problem that is associated with intrahepatic inflammation and impaired immunity. PD-1 is well known to mediate T cell dysfunction but has been reported to promote and attenuate acute inflammation in various injury models. With the use of a well-established murine model of BDL, we studied the effects of intrahepatic PD-1 expression on LTC function, inflammation, and cholestasis. Following BDL, PD-1 expression increased significantly among LTCs. Increased PD-1 expression following BDL was associated with decreased LTC proliferation and less IFN-γ production. Elimination of PD-1 expression resulted in significantly improved proliferative capacity among LTC following BDL, in addition to a more immunostimulatory cytokine profile. Not only was LTC function rescued in PD-1(-/-) mice, but also, the degrees of biliary cell injury, cholestasis, and inflammation were diminished significantly compared with WT animals following BDL. PD-1-mediated acute inflammation following BDL was associated with expansions of intrahepatic neutrophil and Th17 cell populations, with the latter dependent on IL-6. PD-1 blockade represents an attractive strategy for reversing intrahepatic immunosuppression while limiting inflammatory liver damage.
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Abstract
Natural killer (NK) cells are enriched in lymphocytes within the liver and have unique phenotypic features and functional properties, including tumor necrosis factor-related apoptosis-inducing ligand-dependent cytotoxicity and specific cytokine profiles. As a key component of innate immunity in the liver, NK cells perform critical roles in host defense against pathogens and tumors through their natural cytotoxicity and cytokine production, and they also act as regulatory cells by engaging in reciprocal interactions with other types of liver cells through cell-to-cell contact and the production of cytokines. Accumulating evidence from the last decade suggests that NK cells play an important role in controlling viral hepatitis, liver fibrosis, and liver tumorigenesis, but also contribute to the pathogenesis of liver injury and inflammation. The characterization of intrahepatic NK cell functions has not only helped us to better understand the pathogenesis of liver disease, but has also revealed new therapeutic targets for managing this disease.
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Affiliation(s)
- Zhigang Tian
- Department of Microbiology and Immunology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Yongyan Chen
- Department of Microbiology and Immunology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Bin Gao
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
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Duwaerts CC, Gehring S, Cheng CW, van Rooijen N, Gregory SH. Contrasting responses of Kupffer cells and inflammatory mononuclear phagocytes to biliary obstruction in a mouse model of cholestatic liver injury. Liver Int 2013; 33:255-65. [PMID: 23240869 PMCID: PMC3540118 DOI: 10.1111/liv.12048] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 10/08/2012] [Accepted: 11/05/2012] [Indexed: 12/12/2022]
Abstract
BACKGROUND Biliary obstruction and cholestasis are serious complications of many liver diseases. Although resident hepatic macrophages (Kupffer cells) are frequently implicated in disease progression, most studies fail to differentiate the contribution of Kupffer cells and inflammatory mononuclear phagocytes (iMNPs) that infiltrate the liver subsequent to obstruction. AIM This study was undertaken to examine the roles and potential interactions of these two disparate mononuclear phagocyte populations in hepatic injury attending cholestasis. METHODS Female, C57Bl/6 mice were injected with magnetic beads on day 3 prior to sham operation or bile duct ligation (BDL) to facilitate subsequent Kupffer cell isolation. Three days post-surgery, animals were euthanized, and bead-containing Kupffer cells and iMNPs were separated, purified and analysed. To examine the ability of Kupffer cells to modulate iMNP activity, iMNPs were isolated from the livers of intact and Kupffer cell-depleted mice on day 3 post-surgery and compared. RESULTS Purified Kupffer cells and iMNP populations obtained from BDL mice exhibited heterogeneous morphologies rendering them visually indistinguishable. iMNPs, however, were characterized by the increased expression of Ly-6C and CD11b and the elevated production of chemokines/cytokines characteristic of inflammatory cells. In the absence of Kupffer cells, iMNPs immigrating to the liver following BDL exhibited significant decreases in CD11b and Ly-6C expression, and in pro-inflammatory chemokine/cytokine production. CONCLUSIONS Kupffer cells and iMNPs exhibit disparate biological responses to biliary obstruction and cholestasis. Kupffer cells play a key role in regulating iMNP influx and activity.
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Affiliation(s)
- Caroline C. Duwaerts
- Department of Medicine, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI
| | - Stephan Gehring
- Kinderklinik der Universitätsmedizin der Johannes Gutenberg-Universität, Langenbeckstr.1, 55124 Mainz, Germany
| | - Chao-Wen Cheng
- Graduate Institute of Clinical Medicine, School of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Nico van Rooijen
- Department of Cell Biology, Vrije Universiteit, Amsterdam, The Netherlands
| | - Stephen H. Gregory
- Department of Medicine, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI
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Yang Q, Shi Y, He J, Chen Z. The evolving story of macrophages in acute liver failure. Immunol Lett 2012; 147:1-9. [PMID: 22820147 DOI: 10.1016/j.imlet.2012.07.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/15/2012] [Accepted: 07/10/2012] [Indexed: 12/21/2022]
Abstract
Acute liver failure (ALF) remains a worldwide problem. The innate immune system acts as an important regulator of ALF. Kupffer cells (KCs), the resident macrophages in liver, play a key role in liver innate immune response. Recent researches have shown that macrophages display a remarkable plasticity and can differentiate into functionally diverse subsets. However, the dynamic polarized phenotypes and functional status of macrophages at different stage of ALF are not clear. In this paper, we present a review of evidence that KCs play a significant role in the pathogenesis of ALF, including the phenotype and functions of macrophages, signaling pathways involved in macrophage functional status and cell-crosstalks of KCs with other immune cells. More information on macrophages will promote a better understanding of the cellular molecular mechanisms of ALF and provide new insights for the development of therapeutic targets for ALF.
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Affiliation(s)
- Qiao Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital, Medical College, Zhejiang University, Zhejiang, PR China.
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Gao B, Seki E, Brenner DA, Friedman S, Cohen JI, Nagy L, Szabo G, Zakhari S. Innate immunity in alcoholic liver disease. Am J Physiol Gastrointest Liver Physiol 2011. [PMID: 21252049 DOI: 10.1152/ajpqi.00537.2010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Excessive alcohol consumption is a leading cause of chronic liver disease in the Western world. Alcohol-induced hepatotoxicity and oxidative stress are important mechanisms contributing to the pathogenesis of alcoholic liver disease. However, emerging evidence suggests that activation of innate immunity involving TLR4 and complement also plays an important role in initiating alcoholic steatohepatitis and fibrosis, but the role of adaptive immunity in the pathogenesis of alcoholic liver disease remains obscure. Activation of a TLR4-mediated MyD88-independent (TRIF/IRF-3) signaling pathway in Kupffer cells contributes to alcoholic steatohepatitis, whereas activation of TLR4 signaling in hepatic stellate cells promotes liver fibrosis. Alcohol consumption activates the complement system in the liver by yet unidentified mechanisms, leading to alcoholic steatohepatitis. In contrast to activation of TLR4 and complement, alcohol consumption can inhibit natural killer cells, another important innate immunity component, contributing to alcohol-mediated acceleration of viral infection and liver fibrosis in patients with chronic viral hepatitis. Understanding of the role of innate immunity in the pathogenesis of alcoholic liver disease may help us identify novel therapeutic targets to treat this disease.
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Affiliation(s)
- Bin Gao
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Gao B, Seki E, Brenner DA, Friedman S, Cohen JI, Nagy L, Szabo G, Zakhari S. Innate immunity in alcoholic liver disease. Am J Physiol Gastrointest Liver Physiol 2011; 300:G516-25. [PMID: 21252049 PMCID: PMC3774265 DOI: 10.1152/ajpgi.00537.2010] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 01/12/2011] [Indexed: 02/06/2023]
Abstract
Excessive alcohol consumption is a leading cause of chronic liver disease in the Western world. Alcohol-induced hepatotoxicity and oxidative stress are important mechanisms contributing to the pathogenesis of alcoholic liver disease. However, emerging evidence suggests that activation of innate immunity involving TLR4 and complement also plays an important role in initiating alcoholic steatohepatitis and fibrosis, but the role of adaptive immunity in the pathogenesis of alcoholic liver disease remains obscure. Activation of a TLR4-mediated MyD88-independent (TRIF/IRF-3) signaling pathway in Kupffer cells contributes to alcoholic steatohepatitis, whereas activation of TLR4 signaling in hepatic stellate cells promotes liver fibrosis. Alcohol consumption activates the complement system in the liver by yet unidentified mechanisms, leading to alcoholic steatohepatitis. In contrast to activation of TLR4 and complement, alcohol consumption can inhibit natural killer cells, another important innate immunity component, contributing to alcohol-mediated acceleration of viral infection and liver fibrosis in patients with chronic viral hepatitis. Understanding of the role of innate immunity in the pathogenesis of alcoholic liver disease may help us identify novel therapeutic targets to treat this disease.
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Affiliation(s)
- Bin Gao
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892, USA.
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