Article

Cyclic Adenosine Monophosphate-Responsive Element Modulator Alpha Overexpression Impairs Function of Hepatic Myeloid-Derived Suppressor Cells and Aggravates Immune-Mediated Hepatitis in Mice

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Abstract

Unlabelled: Molecular factors driving immune-mediated inflammation in the liver are incompletely understood. The transcription factor, cyclic adenosine monophosphate-responsive element modulator alpha (CREMα) can endorse differentiation of T lymphocytes toward T-helper (Th)17 cells, thereby promoting autoimmunity in systemic lupus erythematosus or lung inflammation. To investigate the role of CREMα in liver disease, we subjected transgenic (Tg) mice overexpressing CREMα under control of the CD2 promoter (cremtg mice), which restrains expression mainly to lymphocytes (T, natural killer [NK], and NKT cells), to acute and chronic liver injury models. Already in steady state, Tg CREMα overexpression broadly reduced hepatic immune cell numbers by decreasing their viability, but did not affect immune cell migration or the fibrogenic response to chronic liver injury. Strikingly, cremtg mice developed more severe immune-mediated hepatitis with a higher mortality rate, compared to wild-type (wt) mice, upon concanavalin A (ConA) administration. Unlike in T cells from spleen, CREMα overexpression did not induce a predominant Th17 response in intrahepatic T cells, given that hepatic cremtg CD4+ T cells expressed less interleukin (IL)-17 than wt T cells. Reconstitution of Rag1-/- mice with Crem-/- T cells did not ameliorate ConA hepatitis. Overexpression of CREMα did not influence NK and NKT-cell effector functions either. Interestingly, a subset of monocytic myeloid-derived suppressor cells (MDSCs) also expressed CD2 and CREMα. Cremtg MDSCs isolated from liver expressed reduced inducible nitric oxide synthase and arginase 1 and displayed a reduced T-cell suppressive activity. The adoptive transfer of wt MDSCs was capable of reducing the fulminant immune-mediated liver damage in cremtg mice to wt level. Conclusion: These results suggest compartmental differences of T cell activation pathways between liver and other organs in autoimmunity and define a functional role of CREMα in hepatic monocytic MDSCs for the pathogenesis of immune-mediated liver disease.

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... Recently, MDSC have been studied in the context of acute liver inflammation and are usually associated with protective functions in this setting. We and others could show that MDSC accumulate in the liver during Concanavalin A (ConA)-, D-galactosamine (D-gal) and picryl chloride-induced hepatitis [3,4,[44][45][46][47] and protect the liver from excessive damage. However, there seems to be controversy about which subsets are preferentially involved and which suppressive mechanisms they use. ...
... In this setting, the ratio of gMDSC to mMDSC was about 2:1, and T cell responses were inhibited in an arginase-dependent manner with mMDSC being more suppressive than gMDSC [4] . Consistently, we have shown that inhibiting the suppressive capacity specifically in the mMDSC subset led to severely aggravated hepatitis upon ConA-challenge [44] . Similar observations were also made by another group studying the role of FTY720, a sphingosine-1-phosphate receptor agonist, in recruitment of MDSC to the liver [46,47] . ...
... Interestingly, IL-10 production was induced upon contact with activated HSC in vitro, suggesting a mechanism for the beneficial effects observed in patients and mice with hepatic fibrosis treated with infusion of bone marrow cells [51] . On the contrary, liver fibrosis development upon chronic injury was not affected in a mouse model of transgenic overexpression of the transcription factor crem-alpha, which impairs the functionality of hepatic mMDSC [44] . Thus, more data are needed to define the possible role of MDSC in chronic inflammatory settings in the liver, and their involvement may likely vary depending on the etiology of the underlying disease, e.g., autoimmunity, chronic viral hepatitis or metabolic injury. ...
Article
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Myeloid derived suppressor cells (MDSC) are a heterogeneous population of immune cells that are potent suppressors of immune responses. MDSC emerge in various compartments in the body, such as blood, bone marrow or spleen, especially in conditions of cancer, infections or inflammation. MDSC usually express CD11b, CD33, and low levels of human leukocyte antigen-DR in humans or CD11b and Gr1 (Ly6C/G) in mice, and they can be further divided into granulocytic or monocytic MDSC. The liver is an important organ for MDSC induction and accumulation in hepatic as well as extrahepatic diseases. Different hepatic cells, especially hepatic stellate cells, as well as liver-derived soluble factors, including hepatocyte growth factor and acute phase proteins (SAA, KC), can promote the differentiation of MDSC from myeloid cells. Importantly, hepatic myeloid cells like neutrophils, monocytes and macrophages fulfill essential roles in acute and chronic liver diseases. Recent data from patients with liver diseases and animal models linked MDSC to the pathogenesis of hepatic inflammation, fibrosis and hepatocellular carcinoma (HCC). In settings of acute hepatitis, MDSC can limit immunogenic T cell responses and subsequent tissue injury. In patients with chronic hepatitis C, MDSC increase and may favor viral persistence. Animal models of chronic liver injury, however, have not yet conclusively clarified the involvement of MDSC for hepatic fibrosis. In human HCC and mouse models of liver cancer, MDSC are induced in the tumor environment and suppress anti-tumoral immune responses. Thus, the liver is a primary site of MDSC in vivo, and modulating MDSC functionality might represent a promising novel therapeutic target for liver diseases.
... In mice, MDSCs (CD11b + Gr1 + ) are categorized into two major subsets based on the cell morphology and phenotype and are commonly defined as polymorphonuclear (PMN)-MDSC ( C D1 1 b + Ly 6G + Ly6C l o ) a nd mono cyti c (M)-MDSC (CD11b + Ly6G − Ly6C high ) (3). MDSCs have been demonstrated to protect liver from immune injury in inflammatory murine models, by inhibiting proliferation and cytotoxicity of T lymphocytes (4)(5)(6)(7). Moreover, evidence provided by us and others described the clinical significance of MDSCs in autoimmune liver diseases (AILD), including AIH and primary biliary cholangitis (PBC), indicating MDSCs as a potential target for the immunotherapy of AILD (8)(9)(10). ...
... MDSCs were purified from the bone marrow of LXRa −/− mice and WT mice treated with ConA for 3 h. Subsequently, 5 × 10 6 MDSCs/mouse were transferred through tail-vein injection, and recipient WT mice were treated with ConA 1 h later. Mice were killed 16 h following ConA challenge and assessed for liver histology and transaminase levels. ...
Article
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Myeloid-derived suppressor cells (MDSCs) emerge as a promising candidate for the immunotherapy of autoimmune hepatitis (AIH). However, targets for modulating MDSC in AIH are still being searched. Liver X receptors (LXRs) are important nuclear receptors linking lipid metabolism and immune responses. Despite the extensive studies of LXR in myeloid compartment, its role in MDSCs is currently less understood. Herein, expression of LXRα was found to be upregulated in AIH patients and colocalized with hepatic MDSCs. In ConA-induced hepatitis, deletion of LXRα led to increased expansion of MDSCs in the liver and alleviated the hepatic injury. MDSCs in LXRα-/- mice exhibited enhanced proliferation and survival comparing with WT mice. T-cell proliferation assay and adoptive cell transfer experiment validated the potent immunoregulatory role of MDSCs in vitro and in vivo. Mechanistically, MDSCs from LXRα-/- mice possessed significantly lower expression of interferon regulatory factor 8 (IRF-8), a key negative regulator of MDSC differentiation. Transcriptional activation of IRF-8 by LXRα was further demonstrated. Conclusion: We reported that abrogation of LXRα facilitated the expansion of MDSCs via downregulating IRF-8, and thereby ameliorated hepatic immune injury profoundly. Our work highlights the therapeutic potential of targeting LXRα in AIH.
... It is observed that in autoimmune diseases, naive Tcell differentiation to Th17 cells was driven by a transcription factor CREMα [43]. Contradictory to previous findings, the suppressive function of hepatic MDSCs was impaired by CREMα by reducing iNOS and ARG1 expression [43]. ...
... It is observed that in autoimmune diseases, naive Tcell differentiation to Th17 cells was driven by a transcription factor CREMα [43]. Contradictory to previous findings, the suppressive function of hepatic MDSCs was impaired by CREMα by reducing iNOS and ARG1 expression [43]. It was emphasized that immune-mediated hepatitis aggravates due to overexpression of CREMα. ...
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Background: Myeloid-derived suppressor cells (MDSCs) are immunosuppressive in nature, originate in the bone marrow, and are mainly found in the blood, spleen, and liver. In fact, liver acts as an important organ for induction and accumulation of MDSCs, especially during infection, inflammation, and cancer. In humans and rodents, models of liver diseases revealed that MDSCs promote regeneration and drive the inflammatory processes, leading to hepatitis, fibrogenesis, and cirrhosis, ultimately resulting in hepatocellular carcinoma. Summary: This brief review is focused on the in-depth understanding of the key molecules involved in the expansion and regulation of MDSCs and their underlying immunosuppressive mechanisms in liver diseases. Key Message: Modulated MDSCs can be used for therapeutic purposes in inflammation, cancer, and sepsis.
... Myeloid cells can furthermore adopt an immunosuppressive phenotype, termed "myeloid-derived suppressor cells" (MDSC), that efficiently inhibits T-cell responses and is associated with viral persistence in patients with chronic HBV infections 159,160 . The molecular factors controlling this T-cell-suppressive differentiation of monocyte-derived cells are not fully understood, but animal models implied the transcription factor cAMP-responsive element modulator alpha in monocytic MDSC differentiation specifically in the liver 161 . Although monocytic MDSCs have been related to T-cell suppression in experimental hepatitis and tumour models in mice 161,162 , the arginase-expressing granulocytic MDSCs seem essential to suppress immunopathology in patients with hepatitis B 159 . ...
... The molecular factors controlling this T-cell-suppressive differentiation of monocyte-derived cells are not fully understood, but animal models implied the transcription factor cAMP-responsive element modulator alpha in monocytic MDSC differentiation specifically in the liver 161 . Although monocytic MDSCs have been related to T-cell suppression in experimental hepatitis and tumour models in mice 161,162 , the arginase-expressing granulocytic MDSCs seem essential to suppress immunopathology in patients with hepatitis B 159 . Dependent on the underlying type of injury or disease, different alarmins, danger signals such as ATP, HMGB1, cholesterol or FFAs are released, especially by hepatocytes and also Kupffer cells. ...
Article
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The liver is a central immunological organ with a high exposure to circulating antigens and endotoxins from the gut microbiota, particularly enriched for innate immune cells (macrophages, innate lymphoid cells, mucosal-associated invariant T (MAIT) cells). In homeostasis, many mechanisms ensure suppression of immune responses, resulting in tolerance. Tolerance is also relevant for chronic persistence of hepatotropic viruses or allograft acceptance after liver transplantation. The liver can rapidly activate immunity in response to infections or tissue damage. Depending on the underlying liver disease, such as viral hepatitis, cholestasis or NASH, different triggers mediate immune-cell activation. Conserved mechanisms such as molecular danger patterns (alarmins), Toll-like receptor signalling or inflammasome activation initiate inflammatory responses in the liver. The inflammatory activation of hepatic stellate and Kupffer cells results in the chemokine-mediated infiltration of neutrophils, monocytes, natural killer (NK) and natural killer T (NKT) cells. The ultimate outcome of the intrahepatic immune response (for example, fibrosis or resolution) depends on the functional diversity of macrophages and dendritic cells, but also on the balance between pro-inflammatory and anti-inflammatory T-cell populations. As reviewed here, tremendous progress has helped to understand the fine-tuning of immune responses in the liver from homeostasis to disease, indicating promising targets for future therapies in acute and chronic liver diseases.
... Cannabidiol or IL-25 leads to increased numbers of hepatic CD11b + Gr-1 + cells, and alters the ratio of gMDSC to m-MDSC. T cell responses are inhibited in an arginasedependent manner, dominantly by m-MDSC [48,50]. Treatment with sphingosine-1-phosphate receptor agonist FTY720 also recruits MDSC to the liver, but the suppressive function depends on iNOS and NO production [51]. ...
... Suppressor [46] AIH Mouse G-MDSC Liver Suppressor [50,51] Mouse M-and GMDSC Liver Suppressor (M) [52] T1D-type 1 autoimmune diabetes; RA-rheumatoid arthritis; SLE-systemic lupus erythematosus; IBD-inflammatory bowel disease; EAE-experimental autoimmune encephalomyelitis; AIH-autoimmune hepatitis. mechanisms including production of NO, induction of T cell apoptosis and arginase-1. ...
Article
Myeloid-derived suppressor cells are a heterogeneous group of immature myeloid cells with immunoregulatory function. When activated and expanded, these cells can suppress T cell functions via cell-to cell interactions as well as soluble mediators. Recent studies investigated the involvement of MDSC in autoimmune diseases. Some papers have described beneficial effect of MDSC during the course of autoimmune diseases, and suggest a potential role as a treatment option, while others failed to detect these effects. Their contributions to autoimmune diseases are not fully understood, and many questions and some controversies remain as to the expansion, activation, and inhibitory functions of MDSC. This review aims to summarize current knowledge of MDSC in autoimmune disorders.
... Since we observed major differences in the effect of CREMα Tg T cells on the Nemo Δhepa phenotype, associated with their differentiation pattern, 17 we further investigated the Th17 phenotype in hepatic T cells ( figure 6B). Indeed, our FACS analysis revealed that CREMα Tg control mice showed no increase in Rorγt + T cells in the liver. ...
... The expression of CREMα under control of the CD2 promoter in mice has been shown to reduce the number and alter the composition of immune cells in the liver. 17 Previous work in our laboratory 34 has shown the beneficial effects of depleting NK and NKT cells in Nemo Δhepa mice. In the same line of results, Nemo Δhepa /CREMα Tg animals display reduced amounts of NKT cells, and of proinflammatory macrophages, granulocytes, CD11b + DCs and CD8 + T cells, suggesting an overall reduced inflammatory response. ...
Article
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Objective Th17 cells are a subset of CD4⁺ T-helper cells characterised by interleukin 17 (IL-17) production, a cytokine that plays a crucial role in inflammation-associated diseases. The cyclic AMP-responsive element modulator-α (CREMα) is a central mediator of T-cell pathogenesis, which contributes to increased IL-17 expression in patients with autoimmune disorders. Since an increased Th17 response is associated with a poor prognosis in patients with chronic liver injury, we investigated the relevance of Th17 cells for chronic liver disease (CLD) and hepatocarcinogenesis. Design Transgenic mice overexpressing CREMα were crossed with hepatocyte-specific Nemo knockout mice (NemoΔhepa) to generate NemoΔhepa/CREMαTg mice. The impact of CREMαTg on CLD progression was examined. Additionally, soft agar colony formation assays, in vitro studies, adoptive transfer of bone marrow-derived cells (BMDCs) and T cells, and gene arrays in T cells were performed. Results 8-week-old NemoΔhepa/CREMαTg mice presented significantly decreased transaminase levels, concomitant with reduced numbers of CD11b⁺ dendritic cells and CD8⁺ T cells. CREMαTg overexpression in NemoΔhepa mice was associated with significantly reduced hepatic fibrogenesis and carcinogenesis at 52 weeks. Interestingly, hepatic stellate cell-derived retinoic acid induced a regulatory T-cell (Treg) phenotype in CREMαTg hepatic T cells. Moreover, simultaneous adoptive transfer of BMDCs and T cells from CREMαTg into NemoΔhepa mice ameliorated markers of liver injury and hepatitis. Conclusions Our results demonstrate that overexpression of CREMα in T cells changes the inflammatory milieu, attenuating initiation and progression of CLD. Unexpectedly, our study indicates that CREMα transgenic T cells shift chronic inflammation in NemoΔhepa livers towards a protective Treg response.
... STAT3 mediates the expansion and accumulation of MDSCs primarily by stimulating myelopoiesis and inhibiting differentiation of immature myeloid cells via upregulation of S100A8/9, and it fosters survival of MDSCs by inducing the expression of myc, B-cell lymphoma XL (BCL-XL), and cyclin D1 (22)(23)(24). There have been several advances in understanding the molecular mechanisms governing MDSCs accumulation as well as identification of their detrimental role in facilitating the escape of tumor cells from immune surveillance (18); however, it is only in recent years that their protective function has been highlighted in several pathological conditions (25)(26)(27)(28)(29). Notably, in the context of acute hepatitis, MDSCs can limit immunogenic T-cell responses and subsequent tissue damage (30). A study showed that chronic ethanol consumption enhances MDSCs in B16BL6 melanoma-bearing mice (31). ...
... As a matter of fact, a complicated role was indicated from available limited data on the involvement of MDSCs in chronic liver injury (49). Both beneficial and detrimental roles of MDSCs in the setting of chronic hepatofibrogenesis have been revealed (30,57,58). On the one hand, this tolerogenic mechanism may limit immune responses and subsequent hepatic damage, but on the other hand, immune tolerance may inhibit pathogen eradication and facilitate chronic infections (49). ...
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The dual role of ethanol in regulating both pro-inflammatory and anti-inflammatory response has recently been reported. Myeloid-derived suppressor cells (MDSCs) are one of the major components in the immune suppressive network in both innate and adaptive immune responses. In this study, we aim to define the role of a population expressing CD11b+Ly6GhighLy6Cint with immunosuppressive function in response to ethanol-induced acute liver damage. We find this increased granulocytic-MDSCs (G-MDSCs) population in the blood, spleen, and liver of mice treated with ethanol. Depletion of these cells increases serum alanine aminotransferase and aspartate aminotransferase levels, while G-MDSCs population adoptive transfer can ameliorate liver damage induced by ethanol, indicating the protective role in the early stage of alcoholic liver disease. The significant changes of T-cell profiles after G-MDSCs populations adoptive transfer and anti-Gr1 injection signify that both cytotoxic T and T helper cells might be the targeted cells of G-MDSCs. In the in vitro study, we find that myeloid precursors preferentially generate G-MDSCs and improve their suppressive capacity via chemokine interaction and YAP signaling when exposed to ethanol. Furthermore, IL-6 serves as an important indirect factor in mediating the expansion of G-MDSCs populations after acute ethanol exposure. Collectively, we show that expansion of G-MDSCs in response to ethanol consumption plays a protective role in acute alcoholic liver damage. Our study provides novel evidence of the immune response to acute ethanol consumption.
... In some pathological conditions including tumors, infection, and autoimmune disorders, the immature myeloid cells known as MDSCs, are found to stop differentiating and expanding partially, followed by infiltrating into the inflammatory environment, to contribute to negative immune regulating response [39,40]. Thus, this myeloid population has been thought to be a cellular therapeutic source to treat GVHD [41][42][43], autoimmune hepatitis [44,45] as well as inflammatory bowel disease [46,47]. ...
Article
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Aplastic anemia (AA) is a blood disorder resulted from over-activated T-cell related hematopoietic failure, with the characterization of hypocellularity and enhanced adipogenic differentiation of mesenchymal stroma cells (MSCs) in bone marrow (BM). However, little is known about the relationship between immune imbalance and polarized adipogenic abnormity of BM microenvironment in this disease entity. In the present study, we differentiated BM-MSCs into osteoblastic or adipogenic lineages to mimic the osteo-adipogenic differentiation. Activated CD8+ T cells and interferon-γ (IFN-γ) were found to stimulate adipogenesis of BM-MSCs either in vitro or in vivo of AA mouse model. Interestingly, myeloid-derived suppressive cells (MDSCs), one of the immune-regulating populations, were decreased within BM of AA mice. We found that it was not CD11b+Ly6G+Ly6C- granulocytic-MDSCs (gMDSCs) but CD11b+Ly6G-Ly6C+ monocytic-MDSCs (mMDSCs) inhibiting both T cell proliferation and IFN-γ production via inducible nitric oxide synthetase (iNOS) pathway. Single-cell RNA-sequencing (scRNA-seq) of AA- and mMDSCs-treated murine BM cells revealed that mMDSCs transfusion could reconstitute BM hematopoietic progenitors by inhibiting T cells population and signature cytokines and decreasing immature Adipo-Cxcl12-abundant reticular cells within BM. Multi-injection of mMDSCs into AA mice reduced intra-BM T cells infiltration and suppressed BM adipogenesis, which subsequently restored the intra-BM immune balance and eventually prevented pancytopenia and hypo-hematopoiesis. In conclusion, adoptive transfusion of mMDSCs might be a novel immune-regulating strategy to treat AA, accounting for not only restoring the intra-BM immune balance but also improving stroma’s multi-differentiating microenvironment.
... During BCG-induced pleurisy, transmembrane TNF on M-MDSC restricts proliferation of CD4 T cells via interaction with lymphocyte-expressed TNFR2 (80). Results on MDSC interaction with TH17 and TH2 polarized CD4 T cells are contradictory and reports exist of mainly PMN-MDSC-mediated induction and suppression of TH17 responses in cancer, autoimmunity and infection (133)(134)(135)(136)(137)(138), likely indicating that the combination of mediators present in the microenvironment determines the final outcome. In turn, TH1 and TH2 are involved in the expansion and activation of MDSC in cancer and also hepatitis (137,139). ...
Article
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Heterogeneous populations of myeloid regulatory cells (MRC), including monocytes, macrophages, dendritic cells, and neutrophils, are found in cancer and infectious diseases. The inflammatory environment in solid tumors as well as infectious foci with persistent pathogens promotes the development and recruitment of MRC. These cells help to resolve inflammation and establish host immune homeostasis by restricting T lymphocyte function, inducing regulatory T cells and releasing immune suppressive cytokines and enzyme products. Monocytic MRC, also termed monocytic myeloid-derived suppressor cells (M-MDSC), are bona fide phagocytes, capable of pathogen internalization and persistence, while exerting localized suppressive activity. Here, we summarize molecular pathways controlling M-MDSC genesis and functions in microbial-induced non-resolved inflammation and immunopathology. We focus on the roles of M-MDSC in infections, including opportunistic extracellular bacteria and fungi as well as persistent intracellular pathogens, such as mycobacteria and certain viruses. Better understanding of M-MDSC biology in chronic infections and their role in antimicrobial immunity, will advance development of novel, more effective and broad-range anti-infective therapies.
... Cremtg MDSCs isolated from the liver expressed reduced iNOS and ARG1 and displayed a reduced T-cell suppressive activity. The adoptive transfer of wild-type (wt) MDSCs was capable of reducing the fulminant immune-mediated liver damage in Cremtg mice to wt levels [62]. ...
Article
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Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that consists of myeloid progenitor cells and immature myeloid cells. They have been identified as a cell population that may affect the activation of CD4+ and CD8+ T-cells to regulate the immune response negatively, which makes them attractive targets for the treatment of transplantation and autoimmune diseases. Several studies have suggested the potential suppressive effect of MDSCs on allo- and autoimmune responses. Conversely, MDSCs have also been found at various stages of differentiation, accumulating during pathological situations, not only during tumor development but also in a variety of inflammatory immune responses, bone marrow transplantation, and some autoimmune diseases. These findings appear to be contradictory. In this review, we summarize the roles of MDSCs in different transplantation and autoimmune diseases models as well as the potential to target these cells for therapeutic benefit.
... The transcription factor cyclic adenosine monophosphate-responsive element modulator α (CREMα) can trigger differentiation of T lymphocytes toward Th17 cells, thus promoting autoimmunity in systemic lupus erythematosus and lung inflammation. However, in the mouse immune-mediated hepatitis model, hepatic MDSCs that overexpressed CREMα did not induce a predominant Th17 response in intrahepatic T cells [44]. In addition, in a mouse systemic lupus erythematosus (SLE) model, blockade of IL-33 could prevent the progress of SLE, which was associated with expansion of Tregs and MDSCs, and suppression of Th17 cells [45]. ...
Article
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Myeloid-derived suppressor cells (MDSCs) and Th17 cells were first discovered in the fields of cancer and autoimmunity, respectively. In recent years, their activities have been explored in other biological and pathological conditions, such as infective diseases and solid organ transplantation. However, the interplay between MDSCs and Th17 cells and the mechanism of their interaction remain obscure. This review summarized and analyzed the relationship between MDSCs and Th17 cells, both of which participate in tumor, autoimmune disease, infection and other conditions. In tumors, the increase in MDSCs at the tumor site is usually accompanied by the accumulation of Th17 cells. However, their relationship is inconsistent in different tumors. In arthritic mice or rheumatoid arthritis (RA) patients, an increase in MDSCs, which could ameliorate disease symptoms, causes decreased IL-17A gene expression and Th17 cells accumulation. Furthermore, we concluded that the interaction between MDSCs and Th17 cells is mainly mediated by cytokines. However, the mechanisms require further investigation. Determining the details of their interplay will provide a better understanding of immune networks and could lead to the development of immunotherapeutic strategies in the future.
... 12 Both types of models are highly relevant, but reflect different (clinical) scenarios of hepatic inflammation. In case of Con A, immune cells become activated and attack hepatocytes (thereby modeling autoimmune hepatitis and immune-mediated forms of drug-induced liver injury), 27 whereas the CCl 4 model induces immune cell recruitment activation as an indirect consequence of liver injury (thereby modeling pathogen or alcohol-induced toxicity). 28 These prototypic models reveal important insight into the hepatotoxicity of drug delivery systems or the efficacy of anti-inflammatory compounds. ...
Article
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Immunotherapies have the potential to significantly advance treatment of inflammatory disease and cancer, which are in large parts driven by immune cells. Selectins control the first step in immune cell adhesion and extravasation, thereby guiding leukocyte trafficking to tissue lesions. We analyzed four different highly specific selectin-binding glycopolymers, based on linear poly(2-hydroxypropyl)-methacrylamide (PHPMA) polymers. These glycopolymers contain either the tetrasaccharide sialyl-Lewis(X) (SLe(X)), or the individual carbohydrates fucose, galactose, and sialic acids mimicking the complex SLe(X) binding motive. The glycopolymers strongly bind to primary human macrophages, without activating them, and also to primary human blood leukocytes, but poorly to fibroblasts and endothelial cells in vitro. After intravenous injection in mice, all glycopolymers accumulated in the liver without causing hepatotoxicity. The glycosylated binder most potently targeted resident hepatic macrophages (Kupffer cells), and protected mice from acute toxic liver injury in the two different experimental models, carbon tetrachloride (CCl4) or Concanavalin A (ConA)-based hepatitis. Its sulfated counterpart, on the other hand, induced a decrease in infiltrating and resident macrophages, increased T helper cells, and aggravated immune-mediated liver injury. We demonstrate that, in the context of selectin-binding glycopolymers, minor modifications strongly impact leukocyte influx and macrophage activation, thereby ameliorating or aggravating liver inflammation depending on the underlying immunopathology. The non-sulfated random-glycopolymer is a promising candidate for the treatment of inflammatory disease. The modulation of hepatic immune cells by selectin-binding glycopolymers might breach the immunosuppressive hepatic microenvironment and could improve efficacy of immunotherapies for inflammatory disease and cancer.
... Recent study showed that MDSCs derived from bone marrow can produce IL-10 and impair the pro-fibrotic function of activated HSCs, and consequently alleviate liver fibrosis induced by CCl4 (76). On the contrary, the fibrogenic responses to chronic liver injury had not been affected in a CREM-α-overexpressing transgenic mouse model, which impairs the suppressive capacity of hepatic monocytic MDSCs (77). Although there is no direct evidence that Hh signaling can modulate the function of MDSCs in liver fibrosis, research on chronic infection caused by Helicobacter pylori and associated inflammation (53) suggested that the polarization of the invading myeloid cells to MDSCs requires the Hh-regulated transcription factor Gli1. ...
Article
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Liver fibrosis is a wound healing response initiated by inflammation responding for different iterative parenchymal damages caused by diverse etiologies. Immune cells, which exert their ability of either inducing injury or promoting repair, have been regarded as crucial participants in the fibrogenic response. A characteristic feature of the fibrotic microenvironment associated with chronic liver injury is aberrant activation of hedgehog (Hh) signaling pathway. Growing evidence from a number of different studies in vivo and in vitro has indicated that immune-mediated events involved in liver fibrogenesis are regulated by Hh signaling pathway. In this review, we emphasize the impacts of injury-activated Hh signaling on liver fibrogenesis through modulating repair-related inflammation and focus on the regulatory action of aberrant Hh signaling on repair-related inflammatory responses mediated by hepatic classical and non-classical immune cell populations in the progression of liver fibrosis. Moreover, we also assess the potentiality of Hh pathway inhibitors as good candidates for anti-fibrotic therapeutic agents because of their immune regulation actions for fibrogenic liver repair. The identification of immune-modulatory mechanisms of Hh signaling pathway underlying the fibrotic process of chronic liver diseases might provide a basis for Hh-centered therapeutic strategies for liver fibrosis.
... Further, the FXR activation upregulates the expression of PIR-B by binding the PIR-B promoter to enhance the suppressor function of MDSCs which then act as a critical negative feedback loop in immune-mediated liver injury [97]. Lastly, subset of M-MDSC expresses CD2 and CREMα, the overexpression of the latter being associated with reduced inducible nitric oxide synthase and arginase 1 and an impaired T cell suppressive ability and aggravated concanavalin A-induced liver injury [98,99]. ...
Article
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Myeloid cells play a major role in the sensitization to liver injury, particularly in chronic inflammatory liver diseases with a biliary or hepatocellular origin, and the interplay between myeloid cells and the liver may explain the increased incidence of hepatic osteodystrophy. The myeloid cell-liver axis involves several mature myeloid cells as well as immature or progenitor cells with the complexity of the liver immune microenvironment aggravating the mist of cell differentiation. The unique positioning of the liver at the junction of the peripheral and portal circulation systems underlines the interaction of myeloid cells and hepatic cells and leads to immune tolerance breakdown. We herein discuss the scenarios of different chronic liver diseases closely modulated by myeloid cells and illustrate the numerous potential targets, the understanding of which will ultimately steer the development of solid immunotherapeutic regimens. Ultimately, we are convinced that an adequate modulation of the liver microenvironment to modify the functional and quantitative characteristics of myeloid cells will be a successful approach to treating chronic liver diseases of different etiologies.
... Small intestine, blood, bone marrow, and spleen cells were subjected to red blood cell lysis using Pharm Lyse (BD Biosciences, San Jose, USA). Flow cytometric analysis was done as described in detail before (79). Antibodies were purchased peer-reviewed) is the author/funder. ...
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The hypoxia-inducible transcription factor HIF-1 is appreciated as a promising target for cancer therapy. However, conditional deletion of HIF-1 and HIF-1 target genes in cells of the tumor microenvironment can result in accelerated tumor growth, calling for a detailed characterization of the cellular context to fully comprehend HIF-1’s role in tumorigenesis. We dissected cell type-specific functions of HIF-1 for intestinal tumorigenesis by lineage-restricted deletion of the Hif1a locus. Intestinal epithelial cell-specific Hif1a loss reduced activation of wnt/β-catenin, tumor-specific metabolism and inflammation, significantly inhibiting tumor growth. Deletion of Hif1a in myeloid cells reduced the expression of fibroblast-activating factors in tumor-associated macrophages resulting in decreased abundance of tumor-associated fibroblasts and robustly reduced tumor formation. Interestingly, hypoxia was detectable only sparsely and without spatial association with nuclear HIF-1α in intestinal adenomas, pointing towards a functional importance of hypoxia-independent, i.e. non-canonical HIF-1 stabilization that has not been previously appreciated. This adds a further layer of complexity to the regulation of HIF-1α and suggests that hypoxia and HIF-1α stabilization can be uncoupled in cancer. Collectively, our data show that HIF-1 is a pivotal pro-tumorigenic factor for intestinal tumor formation, controlling key oncogenic programs in both the epithelial tumor compartment and the tumor microenvironment.
... MDSCs require different signals for their expansion and activation. A variety of factors play important roles in the expansion of MDSCs such as cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), granulocyte/macrophage colony-stimulating factor (GM-CSF), macrophage colonystimulating factor (M-CSF), IL-6, IL-3, vascular endothelial growth factor (VEGF), and stem cell factor (SCF)-1 [13,[26][27][28][29]. The activation of MDSCs is associated with IFN-γ, TGF-β, IL-13, IL-4, etc. [13]. ...
Article
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Myeloid-derived suppressor cells (MDSCs) are identified as a heterogeneous population of cells with the function to suppress innate as well as adaptive immune responses. The initial studies of MDSCs were primarily focused on the field of animal tumor models or cancer patients. In cancer, MDSCs play the deleterious role to inhibit tumor immunity and to promote tumor development. Over the past few years, an increasing number of studies have investigated the role of MDSCs in autoimmune diseases. The beneficial effects of MDSCs in autoimmunity have been reported by some studies, and thus, immunosuppressive MDSCs may be a novel therapeutic target in autoimmune diseases. There are some controversial findings as well. Many questions such as the activation, differentiation, and suppressive functions of MDSCs and their roles in autoimmune diseases remain unclear. In this review, we have discussed the current understanding of MDSCs in autoimmune diseases.
... Small intestine, blood, bone marrow, and spleen cells were subjected to red blood cell lysis using Pharm Lyse (BD Biosciences, San Jose, USA). Flow cytometric analysis was done as described in detail before [79]. ...
Article
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The hypoxia-inducible transcription factor HIF-1 is appreciated as a promising target for cancer therapy. However, conditional deletion of HIF-1 and HIF-1 target genes in cells of the tumor microenvironment can result in accelerated tumor growth, calling for a detailed characterization of the cellular context to fully comprehend HIF-1’s role in tumorigenesis. We dissected cell type-specific functions of HIF-1 for intestinal tumorigenesis by lineage-restricted deletion of the Hif1a locus. Intestinal epithelial cell-specific Hif1a loss reduced activation of Wnt/β-catenin, tumor-specific metabolism and inflammation, significantly inhibiting tumor growth. Deletion of Hif1a in myeloid cells reduced the expression of fibroblast-activating factors in tumor-associated macrophages resulting in decreased abundance of tumor-associated fibroblasts (TAF) and robustly reduced tumor formation. Interestingly, hypoxia was detectable only sparsely and without spatial association with HIF-1α, arguing for an importance of hypoxia-independent, i.e., non-canonical, HIF-1 stabilization for intestinal tumorigenesis that has not been previously appreciated. This adds a further layer of complexity to the regulation of HIF-1 and suggests that hypoxia and HIF-1α stabilization can be uncoupled in cancer. Collectively, our data show that HIF-1 is a pivotal pro-tumorigenic factor for intestinal tumor formation, controlling key oncogenic programs in both the epithelial tumor compartment and the tumor microenvironment.
... Many toxic substances cause different types of liver damage, both acute injury and chronic injury. Researchers typically use the chemical substances concanavalin A (ConA), Carbon tetrachloride (CCl4), lipopolysaccharide (LPS)/D-galactosamine(GaIN) to induce liver injury in mice and thereby simulate different types of human liver injuries [34][35][36]. IL-22 has been shown to activate a variety of signal transduction pathways, including the activator of transcription factor (STAT) pathway, the Janus kinase-signal transducer pathway and the mitogen-activated protein kinase pathway in hepatic cells. IL-22 plays a protective role in T cell-mediated hepatitis by activating STAT3; Overexpression of IL-22 can significantly increase the activity of STAT3 and the induction of anti-apoptotic proteins such as Bcl-xL, Bcl-2 and Mcl-1 [37] (Figure 2). ...
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Interleukin 22(IL-22), a member of the IL-10 cytokine family and is an emerging CD4+Th cytokine that plays an important role in anti-microbial defense, homeostasis and tissue repair. We are interested in IL-22 as it has the double function of suppressing or encouraging inflammation in various disease models including hepatic inflammation. As a survival factor for hepatocytes, IL-22 plays a protective role in many kinds of liver diseases, such as hepatitis, liver fibrosis, or hepatocellular carcinoma (HCC) by binding to the receptors IL-22R1 and IL-10R2. Overexpression of IL-22 reduces liver fibrosis by attenuating the activation of hepatic stellate cell (the main cell types involved in hepatic fibrosis), and down-regulating the levels of inflammatory cytokines. Administration of exogenous IL-22 increases the replication of hepatocytes by inhibiting cell apoptosis and promoting mitosis, ultimately plays a contributing role in liver regeneration. Furthermore, treatment with IL-22 activates hepatic signal transducer and activator of transcription 3 (STAT3), ameliorates hepatic oxidative stress and alcoholic fatty liver, effectively alleviate the liver damage caused by alcohol and toxicant. In conclusion, the hepatoprotective functions and liver regeneration promoting effect of IL-22 suggests the therapeutic potential of IL-22 in the treatment of human hepatic diseases.
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Calcium calmodulin kinase IV (CaMK4) regulates multiple processes that significantly contribute to the lupus-related pathology by controlling the production of IL-2 and IL-17 by T cells, the proliferation of mesangial cells, and the function and structure of podocytes. CaMK4 is also upregulated in podocytes from patients with focal segmental glomerulosclerosis (FSGS). In both immune and non-immune podocytopathies, CaMK4 disrupts the structure and function of podocytes. In lupus-prone mice, targeted delivery of a CaMK4 inhibitor to CD4+ T cells suppresses both autoimmunity and the development of nephritis. Targeted delivery though to podocytes averts the deposition of immune complexes without affecting autoimmunity in lupus-prone mice and averts pathology induced by adriamycin in normal mice. Therefore, targeted delivery of a CaMK4 inhibitor to podocytes holds high therapeutic promise for both immune (lupus nephritis) and non-immune (FSGS) podocytopathies.
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The Publisher regrets that this article is an accidental duplication of an article that has already been published in Gene Reports, 6 (2017) 116-120, http://dx.doi.org10.1016/j.genrep.2016.11.007. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease caused by the destruction of insulin-producing pancreatic β-cells by autoreactive T cells. Studies in animal models, such as the non-obese diabetic (NOD) mouse reveal that this disease is under the control of several genes that encode molecules implicated in regulation of transcription factors and in T cell activation. In order to underline the role of the genes involved in this regulation pathways, we investigated, using the Sequenom MassARRAY platform, 13 single-nucleotide polymorphisms (SNPs) belonging to CREM, IRF5, STAT4, and STAT5a/b genes in 59 T1D Tunisian families. In the current study, we identified an association with rs17583959 (allele G; Z score = 2.27; p = 0.02; Genotype GG: score = 1.96; p = 0.04) of CREM gene. In LD analysis a strong LD between the 3 CREM variants (Block 1) was detected; rs2384352 was in complete LD with rs1148247. When haplotypes were constructed between CREM polymorphisms (rs1148247, rs17583959, rs2384352), AGA haplotype (H2) was significantly over-transmitted from parents to affected offspring (Z score = 2.988; P = 0.002) and may confer a risk for T1D disease. Whereas, AAG haplotype (H5) (Z score = −2.000; p = 0.045) was less transmitted than expected to affected children suggesting its protective effect against T1D pathology. No significant association in IRF5, STAT4, and STAT5a/b genes were observed. In conclusion, this study shows an eventually involvement of CREM gene in the development of T1D pathology in Tunisian families. These facts are consistent with a major role for transcription factor genes involved in the immune pathways in the control of autoimmunity. Further researches of association and functional analysis across populations are needed to confirm these findings.
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Autoimmune hepatitis (AIH) is a chronic progressive autoimmune disease characterized by hepatic inflammation. This study aimed to investigate the effect of antagomir-155 on Concanavalin A (ConA)-induced AIH, and its possible mechanisms. According to the results, the expression of miR-155 was raised in liver tissues after 48 h exposure to ConA. Treatment with antagomir-155 attenuated ConA-induced liver injury in mice by reducing serum alanine transaminase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) levels. In addition, antagomir-155 significantly alleviated the differentiation of Treg/Th17 cells in the livers of AIH mice, and suppressed Th17 cells-mediated production of pro-inflammatory cytokines IL-17A, IL-23, but not Treg cells-mediated production of anti-inflammatory cytokein IL-10. Finally, the beneficial effect of antagomir-155 on ConA-induced AIH was abolished by administration of recombinant IL-17A. Our data demonstrated that antagomir-155 treatment could prevent AIH via regulating the differentiation of Treg and Th17 cells, suggesting that microRNA-155 may be an intriguing therapeutic target of AIH.
We have found that calcium calmodulin kinase IV is increased in T cells, podocytes, and mesangial cells from patients with systemic lupus erythematosus, as well as in lupus-prone mice, podocytes of patients with focal segmental glomerulosclerosis, and in mice injected with doxorubicin. We showed that this accounts for aberrant T cell function and glomerular damage. Using nanoparticles (nlg) loaded with a small drug inhibitor of calcium calmodulin kinase IV and tagged with antibodies directed to CD4 we have been able to show inhibition of autoimmunity and lupus nephritis. Also, using nlg tagged with antibodies to nephrin, we showed suppression of nephritis in lupus-prone mice and of glomerular damage in mice exposed to doxorubicin. We propose the development of approaches to deliver drugs to cells in a targeted and precise manner.
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Background and aims: Increasing evidence in recent years has suggested that microRNA-7 (miR-7) is an important gene implicated in the development of various diseases including HCC. However, the role of miR-7 in autoimmune hepatitis (AIH) is unknown. Approach and results: Herein, we showed that miR-7 deficiency led to exacerbated pathology in Concanavalin-A-induced murine acute autoimmune liver injury (ALI) model, accompanied by hyperactivation state of CD4+ T cells. Depletion of CD4+ T cells reduced the effect of miR-7 deficiency on the pathology of ALI. Interestingly, miR-7 deficiency elevated CD4+ T-cell activation, proliferation, and cytokine production in vitro. Adoptive cell transfer experiments showed that miR-7def CD4+ T cells could exacerbate the pathology of ALI. Further analysis showed that miR-7 expression was up-regulated in activated CD4+ T cells. Importantly, the transcription of pre-miR-7b, a major resource of mature miR-7 in CD4+ T cells, was dominantly dependent on transcription factor CCAAT enhancer binding protein alpha (C/EBPα), which binds to the core promoter region of the miR-7b gene. Global gene analysis showed that mitogen-activated protein kinase 4 (MAPK4) is a target of miR-7 in CD4+ T cells. Finally, the loss of MAPK4 could ameliorate the activation state of CD4+ T cells with or without miR-7 deficiency. Our studies document the important role of miR-7 in the setting of AIH induced by Concanavalin-A. Specifically, we provide evidence that the C/EBPα/miR-7 axis negatively controls CD4+ T-cell activation and function through MAPK4, thereby orchestrating experimental AIH in mice. Conclusions: This study expands on the important role of miR-7 in liver-related diseases and reveals the value of the C/EBPα/miR-7 axis in CD4+ T-cell biological function for the pathogenesis of immune-mediated liver diseases.
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The intravenous injection of the plant lectin concanavalin A (ConA) is a widely used model for acute immune-mediated hepatitis in mice. In contrast to several other models for acute hepatic damage, ConA-induced injury is primarily driven by the activation and recruitment of T cells to the liver. Hence, the ConA model has unique features with respect to its pathogenesis and important similarities to immune-mediated hepatitis in humans, such as autoimmune hepatitis, acute viral hepatitis or distinct entities of drug toxicity leading to immune activation. However, the ConA model has considerable variability, depending on the preparation of the compound, genetic background of the mice, sex, age and microbial environment of the animal facility barrier. This standard operating procedure (SOP) comprises a detailed protocol for the ConA application, including preparation of ConA working solution, handling of the animals, choice of the appropriate conditions and endpoints, as well as efficient dose-finding. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
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Liver fibrosis is defined as excessive extracellular matrix deposition and is based on complex interactions between matrix-producing hepatic stellate cells and an abundance of liver-resident and infiltrating cells. Investigation of these processes requires in vitro and in vivo experimental work in animals. However, the use of animals in translational research will be increasingly challenged, at least in countries of the European Union, because of the adoption of new animal welfare rules in 2013. These rules will create an urgent need for optimized standard operating procedures regarding animal experimentation and improved international communication in the liver fibrosis community. This review gives an update on current animal models, techniques and underlying pathomechanisms with the aim of fostering a critical discussion of the limitations and potential of up-to-date animal experimentation. We discuss potential complications in experimental liver fibrosis and provide examples of how the findings of studies in which these models are used can be translated to human disease and therapy. In this review, we want to motivate the international community to design more standardized animal models which might help to address the legally requested replacement, refinement and reduction of animals in fibrosis research.
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Many autoimmune diseases are driven by self-reactive T helper (Th) cells. A new population of effector CD4(+) T cells characterized by the secretion of interleukin (IL)-17, referred to as Th17 cells, has been demonstrated to be phenotypically, functionally, and developmentally distinct from Th1 and Th2 cells. Because the liver is known to be an important source of transforming growth factor- β and IL-6, which are cytokines that are crucial for Th17 differentiation, it is very likely that Th17 cells contribute to liver inflammation and autoimmunity. In contrast, another distinct subset of T cells, regulatory T cells (Treg), downregulate immune responses and play an important role in maintaining self-tolerance. In addition, there is a reciprocal relationship between Th17 cells and Tregs, in development and effector functions, and the balance between Th17 and Treg cells can affect the outcome of immune responses, particularly in autoimmune diseases. In this review, we will focus on the latest investigative findings related to Th17 cells in autoimmune liver disease.
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Primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH) represent the three major autoimmune liver diseases (AILD). PBC, PSC, and AIH are all complex disorders in that they result from the effects of multiple genes in combination with as yet unidentified environmental factors. Recent genome-wide association studies have identified numerous risk loci for PBC and PSC that host genes involved in innate or acquired immune responses. These loci may provide a clue as to the immune-based pathogenesis of AILD. Moreover, many significant risk loci for PBC and PSC are also risk loci for other autoimmune disorders, such type I diabetes, multiple sclerosis and rheumatoid arthritis, suggesting a shared genetic basis and possibly similar molecular pathways for diverse autoimmune conditions. There is no curative treatment for all three disorders, and a significant number of patients eventually progress to end-stage liver disease requiring liver transplantation (LT). LT in this context has a favourable overall outcome with current patient and graft survival exceeding 80% at 5 years. Indications are as for other chronic liver disease although recent data suggest that while lethargy improves after transplantation, the effect is modest and variable so lethargy alone is not an indication. In contrast, pruritus rapidly responds. Cholangiocarcinoma, except under rigorous selection criteria, excludes LT because of the high risk of recurrence. All three conditions may recur after transplantation and are associated with a greater risk of both acute cellular and chronic ductopenic rejection. It is possible that a crosstalk between alloimmune and autoimmune response perpetuate each other. An immunological response toward self- or allo-antigens is well recognised after LT in patients transplanted for non-autoimmune indications and sometimes termed “de novo autoimmune hepatitis”. Whether this is part of the spectrum of rejection or an autoimmune process is not clear. In this manuscript, we review novel findings about disease processes and mechanisms that lead to autoimmunity in the liver and their possible involvement in the immune response vs. the graft after LT.
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Tumour-induced granulocytic hyperplasia is associated with tumour vasculogenesis and escape from immunity via T cell suppression. Initially, these myeloid cells were identified as granulocytes or monocytes; however, recent studies have revealed that this hyperplasia is associated with populations of multipotent progenitor cells that have been identified as myeloid-derived suppressor cells (MDSCs). The study of MDSCs has provided a wealth of information regarding tumour pathobiology, has extended our understanding of neoplastic progression and has modified our approaches to immune adjuvant therapy. In this Timeline article, we discuss the history of MDSCs, their influence on tumour progression and metastasis, and the crosstalk between tumour cells, MDSCs and the host macroenvironment.
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The study of the liver as a lymphoid organ is a growing field fueled by our better knowledge of the different component of the immune system and how they orchestrate an immune-related response. The liver have highly specialized mechanisms of immune tolerance, mainly because is continuously exposed to microbial and environmental antigens, and dietary components from the gut. Accordingly, the liver contains specialized lymphoid subpopulations acting as antigen-presenting cells. Growing evidences show that the liver is also associated with obesity-associated diseases because of its immune-related capacity to sense metabolic stress induced by nutritional surplus. Finally, the liver produces a pletora of neo-antigens being the primary metabolic organ of the body. Common immune mechanisms play a key pathogenetic role in most of acute and chronic liver diseases and in the rejection of liver allografts. Any perturbations of liver-related immune functions have important clinical implications. This issue of the Journal of Autoimmunity is focused on the more recent advances in our knowledge related to the loss of liver tolerance, a paradox for a tolerogenic organ, that leads to overactivation of the innate and adaptive immune response and the development of autoimmune liver diseases, such as autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis. The invited expert review articles capture the underlying immunomolecular mechanisms of the development and progression of autoimmune liver diseases, the novel field of the immune-related "liver-gut" axis influences to the development of liver autoimmunity, the predominant role of genetic factors, and the increasingly effective immuno-therapeutic possibilities.
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T-helper 17 (Th17) cells are characterized by producing interleukin-17 (IL-17, also called IL-17A), IL-17F, IL-21, and IL-22 and potentially TNF- α and IL-6 upon certain stimulation. IL-23, which promotes Th17 cell development, as well as IL-17 and IL-22 produced by the Th17 cells plays essential roles in various inflammatory diseases, such as experimental autoimmune encephalomyelitis, rheumatoid arthritis, colitis, and Concanavalin A-induced hepatitis. In this review, we summarize the characteristics of the functional role of Th17 cells, with particular focus on the Th17 cell-related cytokines such as IL-17, IL-22, and IL-23, in mouse models and human inflammatory diseases.
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Transcription factor cAMP response element modulator (CREM)α contributes to various cellular and molecular abnormalities in T cells, including increased IL-17 and decreased IL-2 expression. For development of acute lung injury (ALI), the invasion and regulation of immune cells are highly important, but the role of T cells remains unclear. In this study, we show that CREMα is upregulated in LPS-induced ALI. During the early phase of ALI (day 1), T cell-specific CREMα overexpression enhances the numbers of T cells and expression of TNF-α in bronchoalveolar lavage fluid and deteriorates lung functions. On day 3 of ALI, CREMα transgenic mice present a stronger inflammatory response with higher levels of TNF-α, IL-6, and IL-17 correlating with increased numbers of T cells and neutrophils in bronchoalveolar lavage fluid, whereas expression of Foxp3 and IL-2 and numbers of regulatory T cells are decreased. These changes result in restricted lung function in CREMα transgenic mice. Finally, an adoptive transfer of CREM(-/-) CD4(+) T cells, but not of wild-type T cells into RAG-1(-/-) mice results in ameliorated disease levels. Thus, levels of CREM in T cells determine the outcome of ALI, and CREMα transgenic animals represent a model in which proinflammatory T cells aggravate ALI in different phases of the disease. Given the fact that patients with autoimmune diseases like systemic lupus erythematosus show higher levels of CREMα and an increased susceptibility toward infectious complications, our finding is of potential clinical significance and may enable new therapeutic strategies.
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Interleukin (IL)-17 signaling has been implicated in lung and skin fibrosis. We examined the role of IL-17 signaling in the pathogenesis of liver fibrosis in mice. Using cholestatic and hepatotoxic models of liver injury, we compared the development of liver fibrosis in wild-type mice with that of IL-17RA(-/-) mice and of bone marrow chimeric mice devoid of IL-17 signaling in immune and Kupffer cells (IL-17RA(-/-) to wild-type and IL-17A(-/-) to wild-type mice) or liver resident cells (wild-type to IL-17RA(-/-) mice). In response to liver injury, levels of Il-17A and its receptor increased. IL-17A increased appeared to promote fibrosis by activating inflammatory and liver resident cells. IL-17 signaling facilitated production of IL-6, IL-1, and tumor necrosis factor-α by inflammatory cells and increased the expression of transforming growth factor-1, a fibrogenic cytokine. IL-17 directly induced production of collagen type I in hepatic stellate cells by activating the signal transducer and activator of transcription 3 (Stat3) signaling pathway. Mice devoid of Stat3 signaling in hepatic stellate cells (GFAPStat3(-/-) mice) were less susceptible to fibrosis. Furthermore, deletion of IL-23 from immune cells attenuated liver fibrosis, whereas deletion of IL-22 exacerbated fibrosis. Administration of IL-22 and IL-17E (IL-25, a negative regulator of IL-23) protected mice from bile duct ligation-induced liver fibrosis. IL-17 induces liver fibrosis through multiple mechanisms in mice. Reagents that block these pathways might be developed as therapeutics for patients with cirrhosis.
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IL-17A is a proinflammatory cytokine that is produced by specialized T helper cells and contributes to the development of several autoimmune diseases such as systemic lupus erythematosus (SLE). Transcription factor cAMP-responsive element modulator (CREM)α displays increased expression levels in T cells from SLE patients and has been described to account for aberrant T cell function in SLE pathogenesis. In this report, we provide evidence that CREMα physically binds to a cAMP-responsive element, CRE (-111/-104), within the proximal human IL17A promoter and increases its activity. Chromatin immunoprecipitation assays reveal that activated naïve CD4(+) T cells as well as T cells from SLE patients display increased CREMα binding to this site compared with T cells from healthy controls. The histone H3 modification pattern at the CRE site (-111/-104) and neighboring conserved noncoding sequences within the human IL17A gene locus suggests an accessible chromatin structure (H3K27 hypomethylation/H3K18 hyperacetylation) in activated naïve CD4(+) T cells and SLE T cells. H3K27 hypomethylation is accompanied by decreased cytosine phosphate guanosine (CpG)-DNA methylation in these regions in SLE T cells. Decreased recruitment of histone deacetylase (HDAC)1 and DNA methyltransferase (DNMT)3a to the CRE site (-111/-104) probably accounts for the observed epigenetic alterations. Reporter studies confirmed that DNA methylation of the IL17A promoter indeed abrogates its inducibility. Our findings demonstrate an extended role for CREMα in the immunopathogenesis of SLE because it contributes to increased expression of IL-17A.
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Concanavalin A (Con A)-induced hepatitis is thought to be a T-cell-mediated disease with active destruction of liver cells. Interleukin (IL)-17 is a cytokine produced principally by CD4(+) T cells. However, whether IL-17/IL-17 receptor (IL-17/IL-17R)-mediated responses are involved in T-cell-mediated Con A-induced liver injury remains unclear. In this study, we found that IL-17 expression was highly elevated in liver tissues during Con A-induced hepatitis. The increased levels of IL-17 were paralleled with the severity of liver injury reflected by Alanine aminotransaminase and histological assay as well as the secretion of tumor necrosis factor (TNF)-α and IL-6. Blockage of IL-17 significantly ameliorated Con A-induced hepatitis, while overexpression of IL-17 systemically resulted in massive hepatocyte necrosis in mice. Furthermore, overexpression of an IL-17R immunoglobulin G1 fusion protein significantly attenuated liver inflammation after acute Con A treatment. High expression of IL-17R on Kupffer cells was also observed along with the production of cytokines including TNF-α and IL-6. Inhibition of Kupffer cells by gadolinium chloride completely prevented Con A-induced liver injury and cytokine release. Finally, IL-17-expressing CD4(+) T and natural killer T cells were greatly increased in Con A-injected mice compared with that in controls. Overall, our results indicate that IL-17R signaling is critically involved in the pathogenesis in Con A-induced hepatitis, and blockade of IL-17/IL-17R signaling pathway may represent a novel therapeutic intervention in human autoimmune-related hepatitis.
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Myeloid-derived suppressor cells (MDSCs) are getting increased attention as one of the main regulatory cells of the immune system. They are induced at sites of inflammation and can potently suppress T cell functions. In the current study, we demonstrate how activation of TRPV1 vanilloid receptors can trigger MDSCs, which in turn, can inhibit inflammation and hepatitis. Polyclonal activation of T cells, following injection of concanavalin A (ConA), in C57BL/6 mice caused acute hepatitis, characterized by significant increase in aspartate transaminase (AST), induction of inflammatory cytokines, and infiltration of mononuclear cells in the liver, leading to severe liver injury. Administration of cannabidiol (CBD), a natural non-psychoactive cannabinoid, after ConA challenge, inhibited hepatitis in a dose-dependent manner, along with all of the associated inflammation markers. Phenotypic analysis of liver infiltrating cells showed that CBD-mediated suppression of hepatitis was associated with increased induction of arginase-expressing CD11b(+)Gr-1(+) MDSCs. Purified CBD-induced MDSCs could effectively suppress T cell proliferation in vitro in arginase-dependent manner. Furthermore, adoptive transfer of purified MDSCs into naïve mice conferred significant protection from ConA-induced hepatitis. CBD failed to induce MDSCs and suppress hepatitis in the livers of vanilloid receptor-deficient mice (TRPV1(-/-)) thereby suggesting that CBD primarily acted via this receptor to induce MDSCs and suppress hepatitis. While MDSCs induced by CBD in liver consisted of granulocytic and monocytic subsets at a ratio of ∼2∶1, the monocytic MDSCs were more immunosuppressive compared to granulocytic MDSCs. The ability of CBD to induce MDSCs and suppress hepatitis was also demonstrable in Staphylococcal enterotoxin B-induced liver injury. This study demonstrates for the first time that MDSCs play a critical role in attenuating acute inflammation in the liver, and that agents such as CBD, which trigger MDSCs through activation of TRPV1 vanilloid receptors may constitute a novel therapeutic modality to treat inflammatory diseases.
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Unbalanced Th1/Th2 T-cell responses in the liver are a characteristic of hepatic inflammation and subsequent liver fibrosis. The recently discovered Th17 cells, a subtype of CD4(+) T-helper cells mainly producing IL-17 and IL-22, have initially been linked to host defense against infections and to autoimmunity. Their preferred differentiation upon TGFβ and IL-6, two cytokines abundantly present in injured liver, makes a contribution of Th17 cells to hepatic inflammation very likely. Indeed, initial studies in humans revealed activated Th17 cells and Th17-related cytokines in various liver diseases. However, functional experiments in mouse models are not fully conclusive at present, and the pathogenic contribution of Th17 cells to liver inflammation might vary upon the disease etiology, for example, between infectious and autoimmune disorders. Understanding the chemokines and chemokine receptors promoting hepatic Th17 cell recruitment (possibly CCR6 or CCR4) might reveal new therapeutic targets interfering with Th17 migration or differentiation in liver disease.
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The portal tract mononuclear cell infiltrate has been characterised in 28 liver biopsy samples showing features of chronic aggressive hepatitis from 12 patients with autoimmune chronic active hepatitis, 12 with primary sclerosing cholangitis, and four with other chronic liver diseases (two with alpha 1-antitrypsin deficiency, one with Wilson's disease, and one with chronic hepatitis B infection). In all patients liver disease had started in childhood. The mononuclear cell infiltrate was investigated by a two step immunoperoxidase technique using monoclonal antibodies to: total, alpha/beta T cell receptor positive, helper/inducer, suppressor/cytotoxic T lymphocytes; B lymphocytes; killer/natural killer cells; monocyte/macrophages; and to the activation markers HLA-DR antigens, interleukin 2 receptor (IL-2R), transferrin receptor, and 4F2Ag. In all samples the infiltrate consisted of mainly alpha/beta T cell receptor T lymphocytes. Although T helper/inducer cells predominated in patients with autoimmune chronic active hepatitis, T suppressor/cytotoxic lymphocytes were preponderant in patients with primary sclerosing cholangitis and the other chronic liver diseases. Killer/natural killer cells accounted for up to 25% of the mononuclear cell infiltrate in patients with autoimmune chronic active hepatitis, being rare or absent in the other diseases. Monocytes/macrophages were always found, but they were more numerous in primary sclerosing cholangitis than in the other chronic liver diseases. B lymphocytes were rare or absent in all subjects. Activated mononuclear cells were present in all subjects, but although in patients with autoimmune chronic active hepatitis and primary sclerosing cholangitis most cells of the infiltrate expressed HLA-DR antigens and up to 75% IL-2R, in other forms of chronic liver diseases HLA-DR positive cells were less common and IL-2R positive cells ere rare or absent. These results show that the cells responsible for the histological characteristics of chronic aggressive hepatitis vary in their functional phenotype and state of activation according to the type of underlying liver disorder, confirming the involvement of different pathogenetic mechanisms.
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Male NMRI or BALB/c mice developed severe liver injury as assessed by transaminase release within 8 h when an intravenous dose greater than 1.5 mg/kg concanavalin A (Con A) was given. Histopathologically, only the liver was affected. Electron micrographs revealed leukocyte sticking to endothelial cells and bleb formation of hepatocytes. The hepatotoxicity of the lectin correlated neither with its agglutination activity nor with its sugar specificity. Administration of 0.5 mg/kg dexamethasone or 50 mg/kg cyclosporine A or 50 mg/kg FK 506 (Fujimycin) resulted in protection of the animals whereas indomethacin pretreatment failed to protect. Con A hepatitis was accompanied by the release of IL-2 into the serum of the animals. Mice with severe combined immunodeficiency syndrome lacking B as well as T lymphocytes were resistant against Con A. Athymic nude mice with immature T lymphocytes were also resistant. Pretreatment of mice with an antibody against T lymphocytes fully protected against Con A as did monoclonal anti-mouse CD4. Monoclonal anti-mouse CD8 failed to protect. Pretreatment of mice with silica particles, i.e., deletion of macrophages, prevented the induction of hepatitis. These findings provide evidence that Con A-induced liver injury depends on the activation of T lymphocytes by macrophages in the presence of Con A. The model might allow the study of the pathophysiology of immunologically mediated hepatic disorders such as autoimmune chronic active hepatitis.
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Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease characterized by diverse cellular and biochemical aberrations, including decreased production of IL-2. Here we show that nuclear extracts from unstimulated SLE T cells, unlike extracts from normal T cells, express increased amounts of phosphorylated cAMP-responsive element modulator (p-CREM) that binds the -180 site of the IL-2 promoter. Nuclear extracts from stimulated normal T cells display increased binding of phosphorylated cAMP-responsive element binding protein (p-CREB) to the -180 site of the IL-2 promoter, whereas nuclear extracts from stimulated SLE T cells display primarily p-CREM and decreased p-CREB binding. In SLE T cells, p-CREM bound to the transcriptional coactivators, CREB binding protein and p300. Increased expression of p-CREM correlated with decreased production of IL-2. The transcription of a reporter gene driven by the -180 site was enhanced in normal T cells, but was suppressed in SLE T cells. These experiments demonstrate that transcriptional repression is responsible for the decreased production of IL-2 by SLE T cells.
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The cAMP response element modulator (CREM) has been shown to bind specifically to the -180 site of the IL-2 promoter in vitro. CREM protein is increased in T cells of patients with systemic lupus erythematosus (SLE), and it has been considered responsible for the decreased production of IL-2. In this work we show that transcriptional up-regulation is responsible for the increased CREM protein levels and that CREM binds to the IL-2 promoter in live SLE T cells. Suppression of the expression of CREM mRNA and protein by an antisense CREM plasmid, which was force expressed in SLE T cells by electroporation, resulted in decreased CREM protein binding to the IL-2 promoter and increased expression of IL-2 mRNA and protein. Our data demonstrate that antisense constructs can be used to effectively eliminate the expression of a transcriptional repressor. This approach can be used therapeutically in conditions where increased production of IL-2 is desired.
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Systemic lupus erythematosus (SLE) T cells express high levels of cAMP response element modulator (CREM) that binds to the IL-2 promoter and represses the transcription of the IL-2 gene. This study was designed to identify pathways that lead to increased binding of CREM to the IL-2 promoter in SLE T cells. Ca(2+)/calmodulin-dependent kinase IV (CaMKIV) was found to be increased in the nucleus of SLE T cells and to be involved in the overexpression of CREM and its binding to the IL-2 promoter. Treatment of normal T cells with SLE serum resulted in increased expression of CREM protein, increased binding of CREM to the IL-2 promoter, and decreased IL-2 promoter activity and IL-2 production. This process was abolished when a dominant inactive form of CaMKIV was expressed in normal T cells. The effect of SLE serum resided within the IgG fraction and was specifically attributed to anti-TCR/CD3 autoantibodies. This study identifies CaMKIV as being responsible for the increased expression of CREM and the decreased production of IL-2 in SLE T cells and demonstrates that anti-TCR/CD3 antibodies present in SLE sera can account for the increased expression of CREM and the suppression of IL-2 production.
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Tumor affects myelopoiesis by inhibiting the process of differentiation/maturation of antigen-presenting cells from their myeloid precursors and by stimulating an accumulation of immature myeloid cells in cancer patients and tumor-bearing mice. These immature myeloid cells can contribute greatly to tumor progression and promote tumor evasion from immune attack: i) by inhibiting development of adaptive immune responses against tumor in lymphoid organs; ii) by migrating into tumor site and differentiating there into highly immune suppressive tumor-associated macrophages. Immature myeloid cells and tumor-associated macrophages utilize different JAK/STAT signaling pathways and different mechanisms to control T cell responses, which include increased production of TGF-beta, reactive oxygen species, peroxynitrites, as well as enhanced L-arginine metabolism. Understanding of precise mechanisms, which tumors use to affect differentiation of APC from myeloid cell precursors and inhibit T cell responses, could help to develop new approaches for cancer therapy and substantially improve efficiency of existing cancer vaccination strategies.
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Systemic lupus erythematosus T cells display decreased amounts of TCR zeta mRNA that results in part from limited binding of the transcriptional enhancer Elf-1 to the TCR zeta promoter. We have identified a new cis-binding site for the cAMP response element (CRE) modulator (CREM) on the TCR zeta promoter, centered on the -390 nucleotide. Transfection of T cells with an antisense CREM alpha plasmid reduced the binding of CREM to the TCR zeta promoter, as shown by chromatin and reporter chromatin immunoprecipitation assays, and enhanced the production of TCR zeta mRNA and protein. Mutagenesis of the -390 CRE site prevented the binding of CREM to the TCR zeta promoter. The mechanism of CREM-mediated repression appears to be chromatin dependent, because antisense CREM promotes the acetylation of histones on the TCR zeta promoter. Finally, we established an enhanced binding of CREM to the TCR zeta-chain promoter in systemic lupus erythematosus cells compared with control T cells. Our studies demonstrate that CREM alpha binds to the TCR zeta promoter and repress its activity.
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The induction of CD11b(+)Gr-1(+) myeloid-derived suppressor cells (MDSCs) is an important immune-evading mechanism used by tumors. However, the exact nature and function of MDSCs remain elusive, especially because they constitute a heterogeneous population that has not yet been clearly defined. Here, we identified 2 distinct MDSC subfractions with clear morphologic, molecular, and functional differences. These fractions consisted of either mononuclear cells (MO-MDSCs), resembling inflammatory monocytes, or low-density polymorphonuclear cells (PMN-MDSCs), akin to immature neutrophils. Interestingly, both MO-MDSCs and PMN-MDSCs suppressed antigen-specific T-cell responses, albeit using distinct effector molecules and signaling pathways. Blocking IFN-gamma or disrupting STAT1 partially impaired suppression by MO-MDSCs, for which nitric oxide (NO) was one of the mediators. In contrast, while IFN-gamma was strictly required for the suppressor function of PMN-MDSCs, this did not rely on STAT1 signaling or NO production. Finally, MO-MDSCs were shown to be potential precursors of highly antiproliferative NO-producing mature macrophages. However, distinct tumors differentially regulated this inherent MO-MDSC differentiation program, indicating that this phenomenon was tumor driven. Overall, our data refine tumor-induced MDSC functions by uncovering mechanistically distinct MDSC subpopulations, potentially relevant for MDSC-targeted therapies.
Article
Autoimmune hepatitis (AIH) is a disease of unknown aetiology characterised by interface hepatitis, hypergammaglobulinaemia, circulating autoantibodies and a favourable response to immunosuppression. To review recent advancements in understanding aetiopathogenesis, clinical, serological and histological features, diagnostic criteria and treatment strategies of AIH. Published studies on AIH extracted mainly from PubMed during the last 15 years. Autoimmune hepatitis has a global distribution affecting any age, both sexes and all ethnic groups. Clinical manifestations are variable ranging from no symptoms to severe acute hepatitis and only seldom to fulminant hepatic failure. Autoimmune attack is perpetuated, possibly via molecular mimicry mechanisms, and favoured by the impaired control of regulatory T-cells. A typical laboratory finding is hypergammaglobulinaemia with selective elevation of IgG, although in 15-25% of patients - particularly children, elderly and acute cases - IgG levels are normal. Liver histology and autoantibodies, although not pathognomonic, still remain the hallmark for diagnosis. Immunosuppressive treatment is mandatory and life-saving; however, to meet strict response criteria, the conventional therapy with prednisolone with or without azathioprine is far from ideal. Autoimmune hepatitis remains a major diagnostic and therapeutic challenge. The clinician, the hepato-pathologist and the laboratory personnel need to become more familiar with different expressions of the disease, interpretation of liver histology and autoimmune serology. According to the strict definition of treatment response issued by the 2010 AASLD guidelines, many patients are nonresponders to conventional treatment. Newer immunosuppressive agents targeting pathogenetic mechanisms can improve patient management, which needs to be tailored on a case-by-case basis.
Article
Unlabelled: Chronic liver injury promotes hepatic inflammation, representing a prerequisite for organ fibrosis. We hypothesized a contribution of chemokine receptor CCR6 and its ligand, CCL20, which may regulate migration of T-helper (Th)17, regulatory, and gamma-delta (γδ) T cells. CCR6 and CCL20 expression was intrahepatically up-regulated in patients with chronic liver diseases (n = 50), compared to control liver (n = 5). Immunohistochemistry revealed the periportal accumulation of CCR6(+) mononuclear cells and CCL20 induction by hepatic parenchymal cells in liver disease patients. Similarly, in murine livers, CCR6 was expressed by macrophages, CD4 and γδ T-cells, and up-regulated in fibrosis, whereas primary hepatocytes induced CCL20 upon experimental injury. In two murine models of chronic liver injury (CCl4 and methionine-choline-deficient diet), Ccr6(-/-) mice developed more severe fibrosis with strongly enhanced hepatic immune cell infiltration, compared to wild-type (WT) mice. Although CCR6 did not affect hepatic Th-cell subtype composition, CCR6 was explicitly required by the subset of interleukin (IL)-17- and IL-22-expressing γδ T cells for accumulation in injured liver. The adoptive transfer of WT γδ, but not CD4 T cells, into Ccr6(-/-) mice reduced hepatic inflammation and fibrosis in chronic injury to WT level. The anti-inflammatory function of hepatic γδ T cells was independent of IL-17, as evidenced by transfer of Il-17(-/-) cells. Instead, hepatic γδ T cells colocalized with hepatic stellate cells (HSCs) in vivo and promoted apoptosis of primary murine HSCs in a cell-cell contact-dependent manner, involving Fas-ligand (CD95L). Consistent with γδ T-cell-induced HSC apoptosis, activated myofibroblasts were more frequent in fibrotic livers of Ccr6(-/-) than in WT mice. Conclusion: γδ T cells are recruited to the liver by CCR6 upon chronic injury and protect the liver from excessive inflammation and fibrosis by inhibiting HSCs.
Article
Autoimmune hepatitis is a disease of the hepatic parenchyma that can present in acute or chronic forms. In common with many autoimmune diseases, autoimmune hepatitis is associated with non-organ-specific antibodies in the context of hepatic autoimmunity. This dichotomy has made definition of a unifying hypothesis in the pathophysiology of the disease difficult, although data from the past 8 years have drawn attention to the role of regulatory T cells. Several triggers have been identified, and the disease arises in genetically susceptible individuals. Clinical and biochemical remission is achievable in up to 85% of cases. For the remaining patients, alternative immunosuppression strategies are an option. Liver transplantation provides an excellent outcome for patients with acute liver failure or complications of end-stage liver disease, including hepatocellular carcinoma. Variant or overlapping syndromes are worthy of consideration when unexpected disease features arise.
Article
Unlabelled: Fulminant hepatitis (FH) is a disease characterized by massive destruction of hepatocytes with severe impairment of liver function. The pathogenesis of FH is not fully understood, but hyperactivity of T cells and macrophages with excessive production of cytokines are important hallmarks of the condition. In this study, we investigated the role of interleukin (IL)-25 in FH. IL-25 expression was evaluated in patients with FH and in livers of mice with FH induced by D-galactosamine (D-Gal) and lipopolysaccharide (LPS). Mice were treated with IL-25 before D-Gal/LPS-induced FH and before or after concanavalin A (ConA)-induced FH. Mononuclear cells were isolated from livers of mice treated with or without IL-25 and analyzed for GR1(+) CD11b(+) cells. CFSE-labeled T cells were cocultured with GR1(+) CD11b(+) cells and their proliferation was evaluated by flow cytometry. Mice were also treated with a depleting anti-GR1 antibody before IL-25 and D-Gal/LPS administration. IL-25 was constitutively expressed in mouse and human liver and down-regulated during FH. IL-25 prevented D-Gal/LPS-induced FH and this effect was associated with increased infiltration of the liver with cells coexpressing GR1 and CD11b. In vitro studies showed that GR1(+) CD11b(+) cells isolated from mice given IL-25 inhibited T-cell proliferation. Consistently, in vivo depletion of GR1(+) cells abrogated the protective effect of IL-25 in experimental D-Gal/LPS-induced FH. IL-25 was both preventive and therapeutic in ConA-induced FH. Conclusions: IL-25 expression is markedly reduced during human and experimental FH. IL-25 promotes liver accumulation of GR1(+) CD11b(+) cells with immunoregulatory properties.
Article
SPERMATOGENESIS is a complex developmental process that occurs in several phases. A large number of genes have been identified that are expressed during spermatogenesis1,2, but the biological significance of many of these is not yet known. We have used gene targeting to selectively eliminate the transcription factor CREM (cyclic AMP-responsive element modulator), which is thought to e important for mammalian spermatogenesis3–5. Male mice deficient for all CREM proteins are sterile, as their developing spermatids fail to differentiate into sperm, and postmeiotic gene expression in the testis declines dramatically. The cessation of sperm development is not accompanied by decreases in the levels of follicle-stimulating hormone or testosterone. Our findings indicate that the CREM gene is essential for spermatogenesis, and mice deficient for this transcription factor could serve as a model system for the study of idiopathic infertility in men.
Article
Autoimmune hepatitis (AIH) is a chronic autoimmune inflammation of the liver usually requiring lifelong immunosuppression. Steroids and azathioprine are the standard therapy, but the therapy is accompanied by strong side effects. Due to the fact that AIH is often recognized during the late course of disease, it is difficult to obtain knowledge about the immunological mechanisms responsible for initiation of the disease. Current AIH models have been helpful for understanding and modulating liver immune responses, but are not suited to study mechanisms in chronic AIH or to develop new therapies. While most common hepatitis models are more models of injury, transgenic AIH models deal with short-term hepatitis leading to tolerance, and models with natural antigens are either self-limited or have unknown target antigens. Therefore, new models with defined onset of AIH and a standardized course of disease are essential for a better understanding of the disease and to develop new therapies.
Article
Background Hepatocellular carcinoma (HCC) is a typical inflammation-associated cancer, but may also provoke antitumour immune responses whose significance and underlying mechanisms are incompletely understood. Objective To characterise immune responses in the diethylnitrosamine (DEN)-liver cancer mouse model. Design Tumour development and immune cell functions upon DEN treatment were compared between C57BL/6 wild-type (WT), chemokine scavenging receptor D6-deficient, B cell- (Igh6), CD4 T cell- (MHC-II) and T-/B cell-deficient (Rag1) mice. Relevance for human HCC was tested by comparing gene array results from 139 HCC tissues. Results The induction of premalignant lesions after 24 weeks and of HCC-like tumours after 42 weeks by DEN in mice was accompanied by significant leucocyte infiltration in the liver and upregulation of distinct intrahepatic chemokines (CCL2, CCL5, CXCL9). Macrophages and CD8 (cytotoxic) T cells were most prominently enriched in tumour-bearing livers, similar to samples from human HCC. Myeloid-derived suppressor cells (MDSC) increased in extrahepatic compartments of DEN-treated mice (bone marrow, spleen). The contribution of immune cell subsets for DEN-induced hepatocarcinogenesis was functionally dissected. In D6−/− mice, which lack the chemokine scavenging receptor D6, hepatic macrophage infiltration was significantly increased, but tumour formation and progression did not differ from that of WT mice. In contrast, progression of hepatic tumours (numbers, diameters, tumour load) was strikingly enhanced in T-/B cell-deficient Rag1−/− mice upon DEN treatment. When mice deficient for B cells (Igh6−/−, μMT) or major histocompatibility complex II were used, the data indicated that T cells prevent initial tumour formation, while B cells critically limit growth of established tumours. Accordingly, in tumour-bearing mice antibody production against liver-related model antigen was enhanced, indicating tumour-associated B cell activation. In agreement, T and B cell pathways were differentially regulated in gene array analyses from 139 human HCC tissues and significantly associated with patients' survival. Conclusions Distinct axes of the adaptive immune system, which are also prognostic in human HCC, actively suppress DEN-induced hepatocarcinogenesis by controlling tumour formation and progression.
Article
Unlabelled: Chemokines critically control the infiltration of immune cells upon liver injury, thereby promoting hepatic inflammation and fibrosis. The chemokine receptor CCR8 can affect trafficking of monocytes/macrophages, monocyte-derived dendritic cells (DCs) and T-helper cell (Th) subsets, but its role in liver diseases is currently unknown. To investigate the functional role of CCR8 in liver diseases, ccr8(-/-) and wild-type (WT) mice were subjected to chronic experimental injury models of carbon tetrachloride (CCl(4) ) administration and surgical bile duct ligation (BDL). CCR8 was strongly up-regulated in the injured liver. Ccr8(-/-) mice displayed attenuated liver damage (e.g., ALT, histology, and TUNEL) compared to WT mice and were also protected from liver fibrosis in two independent injury models. Flow cytometry revealed reduced infiltrates of liver macrophages, neutrophils and natural killer cells, whereas hepatic CD4(+) T cells increased. The main CCR8-expressing cells in the liver were hepatic macrophages, and CCR8 was functionally necessary for CCL1-directed migration of inflammatory but not for nonclassical monocytes into the liver. Moreover, the phenotype of liver macrophages from injured ccr8(-/-) animals was altered with increased expression of DC markers and enhanced expression of T-cell-attracting chemokine macrophage inflammatory protein 1-alpha (MIP-1α/CCL3). Correspondingly, hepatic CD4(+) T cells showed increased Th1 polarization and reduced Th2 cells in CCR8-deficient animals. Liver fibrosis progression, but also subsequent T-cell alterations, could be restored by adoptively transferring CCR8-expressing monocytes/macrophages into ccr8(-/-) mice during experimental injury. Conclusions: CCR8 critically mediates hepatic macrophage recruitment upon injury, which subsequently shapes the inflammatory response in the injured liver, affecting macrophage/DC and Th differentiation. CCR8 deficiency protects the liver against injury, ameliorating initial inflammatory responses and hepatic fibrogenesis. Inhibition of CCR8 or its ligand, CCL1, might represent a successful therapeutic target to limit liver inflammation and fibrosis progression.
Article
Recent evidence suggests that IL-17A regulates neutrophil-dependent organ injury. Accordingly, the purpose of this study was to determine the role of IL-17A in neutrophil recruitment after ischemia-reperfusion (I/R) and in subsequent liver injury. Two mouse models including wild-type and IL-17A knockout mice were evaluated for I/R injury. The medial largest lobe of the liver was clamped for 90 min. In another set of experiments, recombinant mouse (rm)IL-17A homodimer or rmIL-17A/F heterodimer were administered to knockout mice before I/R, and liver injury was investigated. Isolated Kupffer cells were incubated with rmIL-17A or rmIL-17F, and production of TNF-α was measured. Studies evaluating the extent of liver injury as measured by serum transaminase levels demonstrated similar levels in the acute phase (6 h) in these two models. In contrast, in the subacute phase (20 h) after I/R, both serum transaminase levels and percent of hepatic necrosis were significantly reduced in the knockout mice compared with the wild-type mice. This reduction in liver injury seen in the knockout mice was associated with suppression of chemokine and adhesion molecule expression and reduction in infiltration of neutrophils into the liver. Administration of rmIL-17A homodimer, but not IL-17A/F heterodimer, increased liver injury in the subacute phase of I/R in KO mice. TNF-α production by isolated Kupffer cells increased significantly in the cells incubated with rmIL-17A compared with rmIL-17F. These results indicate that IL-17A is a key regulator in initiating neutrophil-induced inflammatory responses and hepatic injury in the subacute phase after reperfusion.
Article
Unlabelled: Chemokines modulate inflammatory responses that are prerequisites for organ fibrosis upon liver injury. Monocyte-derived hepatic macrophages are critical for the development, maintenance, and resolution of hepatic fibrosis. The specific role of monocyte-associated chemokine (C-X3-C motif) receptor 1 (CX₃CR1) and its cognate ligand fractalkine [chemokine (C-X3-C motif) ligand 1)] in liver inflammation and fibrosis is currently unknown. We examined 169 patients with chronic liver diseases and 84 healthy controls; we found that CX₃CL1 is significantly up-regulated in the circulation upon disease progression, whereas CX₃CR1 is down-regulated intrahepatically in patients with advanced liver fibrosis or cirrhosis. To analyze the functional relevance of this pathway, two models of experimental liver fibrosis were applied to wild-type (WT) and CX₃CR1-deficient mice. Fractalkine expression was induced upon liver injury in mice, primarily in hepatocytes and hepatic stellate cells. CX₃CR1(-/-) animals developed greater hepatic fibrosis than WT animals with carbon tetrachloride-induced and bile duct ligation-induced fibrosis. CX₃CR1(-/-) mice displayed significantly increased numbers of monocyte-derived macrophages within the injured liver. Chimeric animals that underwent bone marrow transplantation revealed that CX₃CR1 restricts hepatic fibrosis progression and monocyte accumulation through mechanisms exerted by infiltrating immune cells. In the absence of CX₃CR1, intrahepatic monocytes develop preferentially into proinflammatory tumor necrosis factor-producing and inducible nitric oxide synthase-producing macrophages. CX₃CR1 represents an essential survival signal for hepatic monocyte-derived macrophages by activating antiapoptotic bcl2 expression. Monocytes/macrophages lacking CX₃CR1 undergo increased cell death after liver injury, which then perpetuates inflammation, promotes prolonged inflammatory monocyte infiltration into the liver, and results in enhanced liver fibrosis. Conclusion: CX₃CR1 limits liver fibrosis in vivo by controlling the differentiation and survival of intrahepatic monocytes. The opposing regulation of CX₃CR1 and fractalkine in patients suggests that pharmacological augmentation of this pathway may represent a possible therapeutic antifibrotic strategy.
Article
Unlabelled: In addition to liver-resident Kupffer cells, infiltrating immune cells have recently been linked to the development of liver fibrosis. Blood monocytes are circulating precursors of tissue macrophages and can be divided into two functionally distinct subpopulations in mice: Gr1(hi) (Ly6C(hi)) and Gr1(lo) (Ly6C(lo)) monocytes. The role of these monocyte subsets in hepatic fibrosis and the mechanisms of their differential recruitment into the injured liver are unknown. We therefore characterized subpopulations of infiltrating monocytes in acute and chronic carbon tetrachloride (CCl(4))-induced liver injury in mice using flow cytometry and immunohistochemistry. Inflammatory Gr1(hi) but not Gr1(lo) monocytes are massively recruited into the liver upon toxic injury constituting an up to 10-fold increase in CD11b(+)F4/80(+) intrahepatic macrophages. Comparing wild-type with C-C chemokine receptor (CCR2)-deficient and CCR2/CCR6-deficient mice revealed that CCR2 critically controls intrahepatic Gr1(hi) monocyte accumulation by mediating their egress from bone marrow. During chronic liver damage, intrahepatic CD11b(+)F4/80(+)Gr1(+) monocyte-derived cells differentiate preferentially into inducible nitric oxide synthase-producing macrophages exerting proinflammatory and profibrogenic actions, such as promoting hepatic stellate cell (HSC) activation, T helper 1-T cell differentiation and transforming growth factor beta (TGF-beta) release. Impaired monocyte subset recruitment in Ccr2(-/-) and Ccr2(-/-)Ccr6(-/-) mice results in reduced HSC activation and diminished liver fibrosis. Moreover, adoptively transferred Gr1(hi) monocytes traffic into the injured liver and promote fibrosis progression in wild-type and Ccr2(-/-)Ccr6(-/-) mice, which are otherwise protected from hepatic fibrosis. Intrahepatic CD11b(+)F4/80(+)Gr1(+) monocyte-derived macrophages purified from CCl(4)-treated animals, but not naïve bone marrow monocytes or control lymphocytes, directly activate HSCs in a TGF-beta-dependent manner in vitro. Conclusion: Inflammatory Gr1(+) monocytes, recruited into the injured liver via CCR2-dependent bone marrow egress, promote the progression of liver fibrosis. Thus, they may represent an interesting novel target for antifibrotic strategies.
Article
The transmembrane isoform of mucin 1 (MUC1/TM) is a well-recognized tumor antigen, contributing to tumorigenesis and immune evasion. Although MUC1/TM has been correlated with malignancy, we have previously reported on antitumor properties and prevention of tumor development by a secreted splice variant of MUC1 (MUC1/sec). Because myeloid-derived suppressor cells (MDSCs) play a critical role in tumor-induced immunosuppression, we investigated their recruitment by tumor cells expressing either MUC1/TM or MUC1/sec. DA-3 tumor cells expressing MUC1/sec recruit dramatically lower levels of MDSCs, relative to MUC1/TM-expressing DA-3 cells. Because MUC1/sec was previously shown to down-regulate tumor expression of urokinase plasminogen activator (uPA), a protease linked to tumor aggressiveness and metastasis, the potential role of uPA in MDSC recruitment was investigated. Tumor-derived uPA is capable of recruiting MDSCs, and correlates with tumor development. In addition to diminishing recruitment of MDSCs, the effect of MUC1/sec on MDSC-suppressive mechanisms was investigated. MUC1/sec, or its unique immunoenhancing peptide, is capable of blocking expression of arginase 1 and production of reactive oxygen species in MDSCs, implicated in the suppression of T cells. These findings demonstrate a new mechanism of MDSC recruitment, and provide evidence that MUC1/sec has antitumor properties affecting MDSCs.
Article
Using an immunogenic nonmetastatic murine mammary adenocarcinoma (D1-DMBA-3) induced in BALB/c mice by dimethylbenzanthracene, we have previously shown that splenocytes from tumor bearers have depressed lymphocyte responses to mitogens and antigens, including tumor-associated antigens. In addition, they display decreased natural killer and T-cell cytotoxic activities. Macrophages from tumor-bearing mice appear to be responsible for the suppression of T- and B-cell responses to concanavalin A, lipopolysaccharide, and tumor-associated antigens observed in tumor bearers. The appearance of these macrophages in the spleen tightly parallels the progressive growth of the tumor and the concomitant immunosuppression. Simultaneously high levels of macrophage progenitors were observed in blood, bone marrow, lung, and liver. A significant increase of colony-stimulating activity of the granulocyte-macrophage lineage was detected in the sera from tumor-bearing mice. Higher levels of this colony-stimulating activity (CSA) were detected in tumor cystic fluid as compared with the levels in serum. A tumor cell line established in vitro from the D1-DMBA-3 in vivo tumor produces high levels of a factor with CSA in culture supernatant fluids. Partial purification of the CSA from the tumor cell line supernatants was achieved using CentriCell ultrafiltration and SephacrylS-300 chromatography. These studies revealed that the molecular weight of the colony-stimulating-like factor is 32,000 to 35,000. The morphology of the colonies obtained in cultures using this factor is similar to that of the colonies that develop in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) but not with macrophage colony-stimulating factor (M-CSF). CSA from tumor cell supernatants was neutralized by antiserum to GM-CSF but not with anti-M-CSF or anti-granulocyte colony-stimulating factor (G-CSF). Macrophages from bone marrow or peritoneal exudates from normal mice cultured with tumor supernatant for 2 to 3 days strongly inhibit normal splenocyte responses to concanavalin A and lipopolysaccharide. The data suggest that the tumor releases a GM-CSF that alters the hemopoietic system and induces or expands macrophages, which exert a suppressive function on the immune system of tumor-bearing mice.
Article
Monoclonal antibodies specific for the murine CD2 antigen were identified by an efficient screening method utilizing murine CD2 cDNA transfectants. An unexpected expression of CD2 on murine B cells was revealed by immunofluorescence and immunoprecipitation studies with these monoclonal antibodies and by RNA blot analysis for the murine CD2 transcript.
Article
A human CD2 minigene cassette has been used in the past to express several reporter genes in the T cell lineage of transgenic mice. However, in order to achieve appreciable levels of expression it has been necessary to integrate many copies of the transgene. In this report we describe an improved version of this cassette. The new cassette directs the expression of a reporter mouse CD8 alpha cDNA on all T cells of transgenic mice with an efficiency ten times higher than the previous cassette. The new cassette includes 5 kb 5' and 5.5 kb 3' flanking sequences containing, respectively, the promoter and locus control region (LCR) of the human CD2 gene. The LCR confers position independent, transgene copy number dependent expression of the genes linked to it in transgenic mice. The cassette also provides a transcription initiation site, the first intron of human CD2 gene and the two polyadenylation signals found in the 3' untranslated region of hCD2 gene.
Article
CREB and its close relatives are now widely accepted as prototypical stimulus-inducible transcription factors. In many cell types, these factors function as effector molecules that bring about cellular changes in response to discrete sets of instructions. In neurons, a wide range of extracellular stimuli are capable of activating CREB family members, and CREB-dependent gene expression has been implicated in complex and diverse processes ranging from development to plasticity to disease. In this review, we focus on the current level of understanding of where, when, and how CREB family members function in the nervous system.
cAMP-responsive element alterations at the interleukin-17A gene locus in patients with systemic lupus erythematosus
  • Rauen T Hedrich Cm
  • Juang Yt
  • K Tenbrock
  • Gc
Rauen T, Hedrich CM, Juang YT, Tenbrock K, Tsokos GC. cAMP-responsive element alterations at the interleukin-17A gene locus in patients with systemic lupus erythematosus. J Biol Chem 2011;286:43437-43446.
References for Supplemental Material & Methods 1
  • Kr Karlmark
  • R Weiskirchen
  • Hw Zimmermann
  • N Gassler
  • F Ginhoux
  • C Weber
References for Supplemental Material & Methods 1. Karlmark KR, Weiskirchen R, Zimmermann HW, Gassler N, Ginhoux F, Weber C,
Critical role of interleukin-17/interleukin-17 receptor axis in mediating Con A-induced hepatitis Role of IL- 17A in neutrophil recruitment and hepatic injury after warm ischemia-reperfusion mice
  • S Yan
  • L Wang
  • N Liu
  • Y Wang
  • Chu Y Kono
  • H Fujii
  • H Ogiku
  • M Hosomura
  • N Amemiya
  • H Tsuchiya
  • M Hara
Yan S, Wang L, Liu N, Wang Y, Chu Y. Critical role of interleukin-17/interleukin-17 receptor axis in mediating Con A-induced hepatitis. Immunol Cell Biol 2012;90:421-428. 14. Kono H, Fujii H, Ogiku M, Hosomura N, Amemiya H, Tsuchiya M, Hara M. Role of IL- 17A in neutrophil recruitment and hepatic injury after warm ischemia-reperfusion mice. J Immunol 2011;187:4818-4825.
Role of myeloid-derived suppressor cells in amelioration of experimental autoimmune hepatitis following activation of TRPV1 receptors by cannabidiol IL-25 prevents and cures fulminant hepatitis in mice through a myeloid-derived suppressor cell-dependent mechanism
  • Vl Hegde
  • Ps Nagarkatti
  • M Nagarkatti
  • Ml Cupi
  • R Bernardini
  • G Ronchetti
  • I Monteleone
  • M Ranalli
  • E Franze
Hegde VL, Nagarkatti PS, Nagarkatti M. Role of myeloid-derived suppressor cells in amelioration of experimental autoimmune hepatitis following activation of TRPV1 receptors by cannabidiol. PLoS One 2011;6:e18281. 18. Sarra M, Cupi ML, Bernardini R, Ronchetti G, Monteleone I, Ranalli M, Franze E, et al. IL-25 prevents and cures fulminant hepatitis in mice through a myeloid-derived suppressor cell-dependent mechanism. Hepatology 2013;58:1436-1450.
Adaptive immunity suppresses formation and progression of diethylnitrosamineinduced liver cancer Severe impairment of spermatogenesis in mice lacking the CREM gene Chemokine receptor CCR6-dependent accumulation of gammadelta T cells in injured liver restricts hepatic inflammation and fibrosis
  • C Schneider
  • A Teufel
  • T Yevsa
  • F Staib
  • A Hohmeyer
  • G Walenda
  • Hw Zimmermann
Schneider C, Teufel A, Yevsa T, Staib F, Hohmeyer A, Walenda G, Zimmermann HW, et al. Adaptive immunity suppresses formation and progression of diethylnitrosamineinduced liver cancer. Gut 2012;61:1733-1743. 22. Blendy JA, Kaestner KH, Weinbauer GF, Nieschlag E, Schutz G. Severe impairment of spermatogenesis in mice lacking the CREM gene. Nature 1996;380:162-165. 23. Hammerich L, Bangen JM, Govaere O, Zimmermann HW, Gassler N, Huss S, Liedtke C, et al. Chemokine receptor CCR6-dependent accumulation of gammadelta T cells in injured liver restricts hepatic inflammation and fibrosis. Hepatology 2014;59:630-642. 24. Karlmark KR, Zimmermann HW, Roderburg C, Gassler N, Wasmuth HE, Luedde T,
Animal models for autoimmune liver disease--what is relevant for immune-mediated liver disease Function and regulation of CREB family transcription factors in the nervous system
  • M Hardtke-Wolenski
  • R Taubert
  • E Jaeckel
  • Dd Ginty
Hardtke-Wolenski M, Taubert R, Jaeckel E. Animal models for autoimmune liver disease--what is relevant for immune-mediated liver disease. Dig Dis 2012;30 Suppl 1:2-10. 6. Lonze BE, Ginty DD. Function and regulation of CREB family transcription factors in the nervous system. Neuron 2002;35:605-623.