The chemokine receptor CXCR3 limits injury after acute toxic liver damage

Abstract

Although acute liver failure is a rare disease, its presence is associated with high morbidity and mortality in affected patients. While a contribution of the immune system to the outcome of toxic liver failure is anticipated, functionally relevant immune cell receptors for liver cell damage need to be better defined. We here investigate the relevance of the chemokine receptor CXCR3, which is important for hepatic immune cell infiltration, in a model of experimental acute liver failure. Liver injury was induced by a single intraperitoneal injection of carbon tetrachloride (CCl 4 ) in CXCR3 À/À , CCR1 À/À , CCR5 À/À and wild-type mice. In this model, CXCR3 À/À mice displayed augmented liver damage compared with all other mouse strains as assessed by liver histology and serum transaminases 24 and 72 h after injury. Phenotypically, CXCR3 À/À mice had significantly reduced intrahepatic NK and NKT cells after injury at all investigated time points (all Po0.05), but strongly elevated expression levels of IL1-b, TNF-a and IFN-g. In line with a functional role of innate immune cells, wildtype mice depleted for NK cells with an anti-ASIALO GM1 antibody before liver injury also displayed increased liver injury after CCl 4 challenge. CXCR3 À/À and NK cell-depleted mice show reduced apoptotic liver cells (TUNEL assay), but more necrotic hepatocytes. Functionally, the augmented liver cell necrosis in CXCR3 À/À and NK cell-depleted mice was associated with increased expression of high mobility group 1 (HMGB1) protein and a consecutive enhanced infiltration of neutrophils into the liver. In conclusion, the results demonstrate a primarily unexpected beneficial role of CXCR3 in acute toxic liver injury. These findings should be taken into account when planning trials with CXCR3 antagonists. Although liver failure is a quite rare clinical condition, its appearance is associated with high mortality and morbidity in affected individuals. The main identifiable causes of acute liver failure are drugs, toxins and viral infections. 1 From a pathophysiological point of view, acute toxic liver failure results from a massive necrosis of hepatocytes that provokes a strong inflammatory immune response within the liver. 2 Upon activation, liver resident and infiltrating immune cells (including T cells, NK cells and NKT cells) secrete diverse proinflammatory chemokines and cytokines, including interferon (IFN)-g 3,4 which perpetuate liver cell damage. IFN-g in turn strongly activates the transcription of the chemokines CXCL9, CXCL10 and CXCL11. 5 The canonical receptor for all three chemokines is CXCR3, 6 which is expressed on various cell sub-populations within the liver, including liver endothelial cells, stellate cells, T cells, NK cells 7 and NKT cells. 8 The interaction between these three chemokines and their receptor mediates the attachment of these immune cells to endothelial cells 9 and thus appears to be crucial for the recruitment of T, NK and NKT cells into the liver. 10,11 Activated hepatic NKT cells by themselves also secrete la...

HMGB1 in health and disease

“…HMGB1-mediated NK-DC crosstalk is important in the regulation of HIV infection and viral replication partly by inhibition of apoptosis (Gougeon and Bras, 2011; Gougeon et al, 2012; Melki et al, 2010; Saidi et al, 2008). In addition to secretion, NK cells can passively release HMGB1 after acute toxic liver damage, which is CXCR3-dependent (Zaldivar et al, 2012). In addition, HMGB1 binding to TLR4 increases expression of natural killer group 2D (NKG2D) ligands by renal tubular epithelial cells (Chen et al, 2011a).…”

“…CXCR3 −/− , but not CCR1 −/− , CCR5 −/− mice and NK cell-depleted mice display severe liver damage after CCl4 injection partly through increased HMGB1 expression in the liver (Zaldivar et al, 2012); HO1 −/− mice show increased mortality in sepsis partly through increased HMGB1 expression in response to LPS or IL-1β (Garcia-Arnandis et al, 2010a; Takamiya et al, 2009); PI3Kγ −/− mice ameliorated the LPS-induced decrease in myocardial contractility and HMGB1 mycocardial expression (Xu et al, 2010); Single-Ig-interleukin-1 related receptor (SIGIRR) −/− mice show cognitive deficiencies and hippocampal dysfunction with enhanced expression of HMGB1 (Costello et al, 2011); Metalloproteinase Zmpste24 −/− mice exhibit lipodystrophy with upregulated HMGB1 expression (Peinado et al, 2011). …”

Anti-Asialo GM1 NK Cell Depleting Antibody Does Not Alter the Development of Bleomycin Induced Pulmonary Fibrosis

“…Not surprisingly, treatment with anti-asialo GM1 does not result in a 100% depletion of NK cells; therefore we cannot exclude the possibility that the few remaining NK cells may be sufficient to exert their biological functions without detecting a difference in fibrosis or other fibrosis markers (cytokines, weight loss…). However, in other disease models such as liver fibrosis, influenza infection, and pulmonary metastasis that used an anti-asialo GM1 treatment paradigm similar to one we employed, NK cell depletion resulted in dramatic phenotypes [17], [37], [38]. Indeed, while anti-asialo GM1 treatment resulted in similar significant yet incomplete levels of NK cell depletion as achieved in our studies, in other in vivo models this resulted in increased influenza related mortality, liver fibrosis, and pulmonary metastases [17], [37], [38].…”

“…In fibrotic lungs, NK cells are reported to be active participants in an early stage IFN-γ burst, which is a characteristic of the inflammatory phase (days 1–10) post-bleomycin injection 10, 19, 20 . Similar to their functional capabilities in liver fibrosis, NK cells may also dampen fibrosis during the fibrotic phase (days 10–21), by killing activated fibroblasts [6], [10], [17], [26], [27]. Thus, the anti-fibrotic effects associated with NK cells have the capacity to impact the different pathophysiological phases of BIPF.…”

“…Nevertheless, anti-asialo GM1 only effectively eliminates NK cells and basophils in vivo [12], [16]. Other less discriminating NK cell-depleting antibodies exist such as anti-NK1.1, but it also depletes NKT cells, which are significant producers of IFN-γ during BIPF [17]. There are also genetically modified mice with NK cell deficiencies, such as Beige and Stat5 (f/f) Ncr1-iCreTg mice.…”