Gp130-dependent release of acute phase proteins is linked to the activation of innate immune signaling pathways
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ABSTRACT: Gp130 dependent gene expression was analyzed in a previously established hepatocyte-specific gp130-knockout mouse model. Whole transcriptome analysis for isolated hepatocytes was performed to measure tissue specific responses after proinflammatory stimulus with IL-6 across different time points. We observed differences in the hepatocyte-specific transcriptional gp130 dependent response for genes associated with different aspects of the innate immune system. Our findings suggest a complex network of tightly-linked genes involved in the early activation of different parts of the innate immune response including acute phase proteins, complement and coagulation cascade. Total RNA obtained from a total number of 61 samples of isolated hepatocytes of hepatocyte-specific gp130-knockout and gp130flox mice, which were subjected to Il-6 treatment for 0, 1, 3, 6 or 12 hours, respectively.
Project description:Gp130 dependent gene expression was analyzed in a previously established hepatocyte-specific gp130-knockout mouse model. Whole transcriptome analysis for isolated hepatocytes was performed to measure tissue specific responses after proinflammatory stimulus with IL-6 across different time points. We observed differences in the hepatocyte-specific transcriptional gp130 dependent response for genes associated with different aspects of the innate immune system. Our findings suggest a complex network of tightly-linked genes involved in the early activation of different parts of the innate immune response including acute phase proteins, complement and coagulation cascade.
Project description:The liver is a pivotal organ possessing remarkable regenerative capacity. By employing murine liver injury models and lineage tracing strategy, recent studies have demonstrated that differentiated hepatocytes undergo reprogramming to SOX9+HNF4α+ liver progenitor-like cells (LPLCs), and serve as a totally new cell source for mammalian liver regeneration. However, it is largely unknown how hepatocyte reprogramming is regulated. In this study, we focus on analyzing the microenvironment cues in triggering hepatocyte reprogramming in liver injuries. By performing single-cell RNA sequencing (scRNA-seq) of hepatocyte reprogramming in liver injury, we find immune response is significantly activated. Notably, by lineage depletion, macrophages, especially kupffer cells, but not T cells, B cells, natural killer cells or neutrophils, are found essential for hepatocyte reprogramming and liver regeneration. IL-6, derived specifically from activated kupffer cells, triggers hepatocyte reprogramming via gp130/STAT3 signaling. Furthermore, STAT3 triggers gene expression by binding to Arid1a-dependent pre-opened regeneration-responsive enhancers (RREs) of reprogramming genes. Collectively, this study provides key insights into kupffer cells/IL-6/STAT3-mediated hepatocyte reprogramming and liver regeneration, which may serve as the base for new therapeutic strategies in facilitating endogenous repair mechanisms.
Project description:The liver is a pivotal organ possessing remarkable regenerative capacity. By employing murine liver injury models and lineage tracing strategy, recent studies have demonstrated that differentiated hepatocytes undergo reprogramming to SOX9+HNF4α+ liver progenitor-like cells (LPLCs), and serve as a totally new cell source for mammalian liver regeneration. However, it is largely unknown how hepatocyte reprogramming is regulated. In this study, we focus on analyzing the microenvironment cues in triggering hepatocyte reprogramming in liver injuries. By performing single-cell RNA sequencing (scRNA-seq) of hepatocyte reprogramming in liver injury, we find immune response is significantly activated. Notably, by lineage depletion, macrophages, especially kupffer cells, but not T cells, B cells, natural killer cells or neutrophils, are found essential for hepatocyte reprogramming and liver regeneration. IL-6, derived specifically from activated kupffer cells, triggers hepatocyte reprogramming via gp130/STAT3 signaling. Furthermore, STAT3 triggers gene expression by binding to Arid1a-dependent pre-opened regeneration-responsive enhancers (RREs) of reprogramming genes. Collectively, this study provides key insights into kupffer cells/IL-6/STAT3-mediated hepatocyte reprogramming and liver regeneration, which may serve as the base for new therapeutic strategies in facilitating endogenous repair mechanisms.
Project description:Germline cell-derived pluripotent stem cells (GPSCs) are similar to embryonic stem (ES) cells in that they can proliferate intensively and differentiate into a variety of cell types, including cardiomyocytes and neurons. In this report, mouse GPSCs were induced to differentiate into hepatocytes with very high efficiency, and demonstrated, for the first time, to be functional. These hepatocytes were characterised at cellular and molecular levels. The GPSC-derived hepatocytes not only expressed hepatic markers, but were also metabolically active as shown by albumin and haptoglobin secretion, urea synthesis, glycogen storage and indocyanine green uptake. Previous studies have revealed some inherent differences in gene expression between undifferentiated mouse ES cells and GPSCs. We wanted to investigate whether this difference may impact on the hepatocyte differentiation capacity of the GPSCs. Large-scale gene expression profiling revealed a strong similarity between GPSC and ES cells at different stages of induced hepatic differentiation. Moreover, Pearson correlation analysis of the microarray datasets revealed that, at late hepatic differentiation stages, the in vitro-derived cells were closer to fetal mouse primary hepatocytes. Thus, adult GPSCs offer great potential for cell ment therapy for a wide variety of liver diseases. Mouse ES cells and GPSCs at various times of hepatocyte differentiation, compared to embryonal (E16) and postnatal (PN1) mouse primary hepatocytes. The supplementary file 'GSE19044_non-normalized.txt' contains non-normalized data for Samples GSM471318-GSM471359.
Project description:Members of the IL-6 cytokine family contribute to inflammatory and regenerative processes. Engagement of the signalling receptor subunit gp130 is common to almost all members of the family. In the liver, all major cell types respond to IL-6, making it difficult to delineate cell type-specific effects of IL-6 type cytokines. We therefore generated mouse models for liver cell type-specific analysis of IL-6 signalling.
Project description:Pulmonary arterial hypertension (PAH) is characterized by stenosis and occlusions of small pulmonary arteries, leading to elevated pulmonary arterial pressure and right heart failure. Although accumulating evidence shows the importance of interleukin (IL)-6 in the pathogenesis of PAH, the target cells of IL-6 are poorly understood. Using mice harboring the floxed allele of gp130, a subunit of IL-6 receptor, we found substantial Cre recombination in all hematopoietic cell lineages from the primitive hematopoietic stem cell level in SM22α-Cre mice. We also revealed that a CD4+ cell-specific gp130 deletion ameliorated the phenotype of hypoxia-induced pulmonary hypertension in mice. Disruption of IL-6 signaling via deletion of gp130 in CD4+ T cells inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and suppressed the hypoxia-induced increase in T helper 17 cells. To further examine the role of IL-6/gp130 signaling in more severe PH models, we developed Il6 knockout (KO) rats using the CRISPR/Cas9 system and showed that IL-6 deficiency could improve the pathophysiology in hypoxia-, monocrotaline-, and Sugen5416/hypoxia (SuHx)-induced rat PH models. Phosphorylation of STAT3 in CD4+ cells was also observed around the vascular lesions in the lungs of SuHx rat model, but not in Il6 KO rats. Blockade of IL-6 signaling had an additive effect on conventional PAH therapeutics, such as endothelin receptor antagonist (macitentan) and soluble guanylyl cyclase stimulator (BAY41-2272). These findings suggest that IL-6/gp130 signaling in CD4+ cells plays a critical role in the pathogenesis of PAH.
Project description:Acute phase proteins (APPs) are an evolutionarily conserved family of proteins produced mainly in the liver in response to infection and inflammation. Despite vast pro- and anti-inflammatory properties ascribed to individual APPs, their collective function during infections remains poorly defined. Using a murine model for polymicrobial sepsis we show here that abrogation of APP production by hepatocyte-specific gp130 deletion, the signaling receptor shared by IL-6-family cytokines, dramatically increased mortality despite normal bacterial clearance. Hepatic gp130 signaling through signal transducer and activator of transcription (Stat)3 was required to control systemic inflammation. Notably, hepatic gp130/Stat3 activation was also a prerequisite to facilitate mobilization and tissue accumulation of myeloid-derived suppressor cells (MDSCs), a cell population mainly known for anti-inflammatory properties in cancer. We show that MDSCs were critical to regulate innate inflammation and their adoptive transfer efficiently protected gp130-deficient mice from sepsis-associated mortality. We identified serum amyloid A and Cxcl-1/KC as hepatic acute phase genes that cooperatively promoted MDSC mobilization, accumulation and survival. Administration of these proteins efficiently elevated MDSC numbers and reversed dysregulated inflammation and restored survival of gp130-deficient mice. Thus, gp130-dependent communication between the liver and MDSCs through acute phase proteins critically controls inflammatory responses during infection. Control [gp130f/f] and liver-specific Gp130 knockout [gp130delta(hepa)] mice were subjected to polymicrobial sepsis. Twelve hours after induction of sepsis mice were sacrificed and livers were removed. For control treatment mice were sacrified without any prior treatment. Total RNA was isolated and subjected to gene expression profiling.
Project description:All except one cytokine of the Interleukin (IL-)6 family share glycoprotein (gp) 130 as the common b receptor chain. Whereas Interleukin (IL-)11 signal via the non-signaling IL-11 receptor (IL-11R) and gp130 homodimers, leukemia inhibitory factor (LIF) recruits gp130:LIF receptor (LIFR) heterodimers. Using IL-11 as a framework, we exchange the gp130 binding site III of IL-11 with the LIFR binding site III of LIF. The resulting synthetic cytokimera GIL-11 efficiently recruits the non-natural receptor signaling complex consisting of gp130, IL-11R and LIFR resulting in signal transduction and proliferation of factor-depending Ba/F3 cells. Besides LIF and IL-11, GIL-11 does not activate receptor complexes consisting of gp130:LIFR or gp130:IL-11R, respectively. Human GIL-11 shows cross-reactivity to mouse and rescued IL-6R deficient mice following partial hepatectomy, demonstrating gp130:IL-11R:LIFR signaling efficiently induced liver regeneration. With the development of the cytokimera GIL-11, we devise the functional assembly of the non-natural cytokine receptor complex of gp130:IL-11R:LIFR.
Project description:Inflammatory hepatocellular adenomas (IHCA) are benign liver tumours defined by the presence of inflammatory infiltrates and by the elevated expression of inflammatory proteins in tumour hepatocytes1,2. Here we show a striking activation of the IL6 signalling pathway in this tumour type, and sequencing candidate genes pinpointed this response to somatic gain-of-function mutations in the IL6ST gene that encodes the signalling co-receptor gp130. Indeed, ~70% of IHCA harbour small in-frame deletions that target the binding site of gp130 for IL6, and expression of the most frequent gp130 mutant, Delta-STVY190, in hepatocellular cells activates STAT3 in absence of ligand. Further, analysis of hepatocellular carcinomas revealed rare gp130 alterations always accompanied by ß-catenin-activating mutations, suggesting a cooperative effect of these signalling pathways in the malignant conversion of hepatocytes. The recurrent gain-of-function gp130 mutations in these human hepatocellular adenomas explains their inflammatory phenotype, and suggest that similar alterations may occur in other inflammatory epithelial tumours with STAT3 activation.