Puengel T, De Vos S, Hundertmark J, Kohlhepp M, Guldiken N, Pujuguet P, Auberval M, Marsais F, Shoji KF, Saniere L, Trautwein C, Luedde T, Strnad P, Brys R, Cl�ment-Lacroix P, Tacke F
PMID: 32316235 | DOI: 10.3390/jcm9041140
Medium-chain fatty acids (MCFAs) have been associated with anti-steatotic effects in hepatocytes. Expression of the MCFA receptor GPR84 (G protein-coupled receptor 84) is induced in immune cells under inflammatory conditions and can promote fibrogenesis. We aimed at deciphering the role of GPR84 in the pathogenesis of non-alcoholic steatohepatitis (NASH), exploring its potential as a therapeutic target. GPR84 expression is upregulated in liver from patients with non-alcoholic fatty liver disease (NAFLD), correlating with the histological degree of inflammation and fibrosis. In mouse and human, activated monocytes and neutrophils upregulate GPR84 expression. Chemotaxis of these myeloid cells by GPR84 stimulation is inhibited by two novel, small molecule GPR84 antagonists. Upon acute liver injury in mice, treatment with GPR84 antagonists significantly reduced the hepatic recruitment of neutrophils, monocytes, and monocyte-derived macrophages (MoMF). We, therefore, evaluated the therapeutic inhibition of GPR84 by these two novel antagonists in comparison to selonsertib, an apoptosis signal-regulating kinase 1 (ASK1) inhibitor, in three NASH mouse models. Pharmacological inhibition of GPR84 significantly reduced macrophage accumulation and ameliorated inflammation and fibrosis, to an extent similar to selonsertib. In conclusion, our findings support that GPR84 mediates myeloid cell infiltration in liver injury and is a promising therapeutic target in steatohepatitis and fibrosis.
Zerbato, JM;Avihingsanon, A;Singh, KP;Zhao, W;Deleage, C;Rosen, E;Cottrell, ML;Rhodes, A;Dantanarayana, A;Tumpach, C;Tennakoon, S;Crane, M;Price, DJ;Braat, S;Mason, H;Roche, M;Kashuba, ADM;Revill, PA;Audsley, J;Lewin, SR;
PMID: 36502576 | DOI: 10.1016/j.ebiom.2022.104391
HIV can infect multiple cells in the liver including hepatocytes, Kupffer cells and infiltrating T cells, but whether HIV can persist in the liver in people with HIV (PWH) on suppressive antiretroviral therapy (ART) remains unknown.In a prospective longitudinal cohort of PWH and hepatitis B virus (HBV) co-infection living in Bangkok, Thailand, we collected blood and liver biopsies from 18 participants prior to and following ART and quantified HIV and HBV persistence using quantitative (q)PCR and RNA/DNAscope. Antiretroviral (ARV) drug levels were quantified using mass spectroscopy.In liver biopsies taken prior to ART, HIV DNA and HIV RNA were detected by qPCR in 53% (9/17) and 47% (8/17) of participants respectively. Following a median ART duration of 3.4 years, HIV DNA was detected in liver in 61% (11/18) of participants by either qPCR, DNAscope or both, but only at very low and non-quantifiable levels. Using immunohistochemistry, HIV DNA was observed in both hepatocytes and liver infiltrating CD4+ T cells on ART. HIV RNA was not detected in liver biopsies collected on ART, by either qPCR or RNAscope. All ARVs were clearly detected in liver tissue.Persistence of HIV DNA in liver in PWH on ART represents an additional reservoir that warrants further investigation.National Health and Medical Research Council of Australia (Project Grant APP1101836, 1149990, and 1135851); This project has been funded in part with federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. 75N91019D00024.
The American journal of pathology
Gayden, J;Hu, S;Joseph, PN;Delgado, E;Liu, S;Bell, A;Puig, S;Monga, SP;Freyberg, Z;
PMID: 36773785 | DOI: 10.1016/j.ajpath.2023.01.011
Hepatic zonation is critical for most metabolic functions in liver. Wnt signaling plays an important role in establishing and maintaining liver zonation. Yet, the anatomic expression of Wnt signaling components, especially all 10 Frizzled (Fzd) receptors, has not been characterized in adult liver. To address this, we quantitatively mapped the spatial expression of Fzd receptors in adult mouse liver via multiplex fluorescent in situ hybridization. Although all 10 Fzd receptors are expressed within a metabolic unit, Fzd receptors 1, 4, and 6 are the highest expressed. Although most Wnt signaling occurs in zone 3, expression of most Fzd receptors is not zonated. In contrast, Fzd receptor 6 is preferentially expressed in zone 1. We also verified that Wnt2 and Wnt9b expression is highly zonated and primarily found in zone 3. Therefore, our results suggest that zonated Wnt/β-catenin signaling at baseline is mostly due to Wnt2 and Wnt9b rather than zonation of Fzd mRNA expression. Finally, we showed that Fzd receptors and Wnts are not uniformly expressed by all hepatic cell types. Instead, there is broad distribution among both hepatocytes and nonparenchymal cells, including endothelial cells. Overall, our establishment of a definitive mRNA expression atlas, especially of Fzd receptors, opens the door to future functional characterization in healthy and diseased liver states.
Carbonaro, M;Wang, K;Huang, H;Frleta, D;Patel, A;Pennington, A;Desclaux, M;Moller-Tank, S;Grindley, J;Altarejos, J;Zhong, J;Polites, G;Poueymirou, W;Jaspers, S;Kyratsous, C;Zambrowicz, B;Murphy, A;Lin, JC;Macdonald, LE;Daly, C;Sleeman, M;Thurston, G;Li, Z;
PMID: 37058568 | DOI: 10.1126/sciadv.adf4490
Liver steatosis is an increasing health issue with few therapeutic options, partly because of a paucity of experimental models. In humanized liver rodent models, abnormal lipid accumulation in transplanted human hepatocytes occurs spontaneously. Here, we demonstrate that this abnormality is associated with compromised interleukin-6 (IL-6)-glycoprotein 130 (GP130) signaling in human hepatocytes because of incompatibility between host rodent IL-6 and human IL-6 receptor (IL-6R) on donor hepatocytes. Restoration of hepatic IL-6-GP130 signaling, through ectopic expression of rodent IL-6R, constitutive activation of GP130 in human hepatocytes, or humanization of an Il6 allele in recipient mice, substantially reduced hepatosteatosis. Notably, providing human Kupffer cells via hematopoietic stem cell engraftment in humanized liver mice also corrected the abnormality. Our observations suggest an important role of IL-6-GP130 pathway in regulating lipid accumulation in hepatocytes and not only provide a method to improve humanized liver models but also suggest therapeutic potential for manipulating GP130 signaling in human liver steatosis.
Hepatology (Baltimore, Md.)
Liu, T;Wang, Q;Zhou, L;Zhang, P;Mi, L;Qiu, X;Chen, Z;Kuang, H;Li, S;Lin, JD;
PMID: 35950514 | DOI: 10.1002/hep.32719
The mammalian liver harbors heterogeneous cell types that communicate via local paracrine signaling. Recent studies have delineated the transcriptomic landscape of the liver in NASH that provides insights into liver cell heterogeneity, intercellular crosstalk, and disease-associated reprogramming. However, the nature of intrahepatic signaling and its role in NASH progression remain obscure.Here, we performed transcriptomic analyses and identified cardiotrophin-like cytokine factor 1 (CLCF1), a member of the IL-6 family cytokines, as a cholangiocyte-derived paracrine factor that was elevated in the liver from diet-induced NASH mice and patients with NASH. Adenovirus-associated virus-mediated overexpression of CLCF1 in the liver ameliorated NASH pathologies in two diet-induced NASH models in mice, illustrating that CLCF1 induction may serve an adaptive and protective role during NASH pathogenesis. Unexpectedly, messenger RNA and protein levels of leukemia inhibitory factor receptor (LIFR), a subunit of the receptor complex for CLCF1, were markedly downregulated in NASH liver. Hepatocyte-specific inactivation of LIFR accelerated NASH progression in mice, supporting an important role of intrahepatic cytokine signaling in maintaining tissue homeostasis under metabolic stress conditions.Together, this study sheds light on the molecular nature of intrahepatic paracrine signaling during NASH pathogenesis and uncovers potential targets for therapeutic intervention.
Hepatology (Baltimore, Md.)
Balog, S;Fujiwara, R;Pan, SQ;El-Baradie, KB;Choi, HY;Sinha, S;Yang, Q;Asahina, K;Chen, Y;Li, M;Salomon, M;Ng, SW;Tsukamoto, H;
PMID: 36181700 | DOI: 10.1002/hep.32793
Relative roles of HSCs and portal fibroblasts in alcoholic hepatitis (AH) are unknown. We aimed to identify subpopulations of collagen type 1 alpha 1 (Col1a1)-expressing cells in a mouse AH model by single-cell RNA sequencing (scRNA-seq) and filtering the cells with the HSC (lecithin retinol acyltransferase [Lrat]) and portal fibroblast (Thy-1 cell surface antigen [Thy1] and fibulin 2 [Fbln2]) markers and vitamin A (VitA) storage.Col1a1-green fluorescent protein (GFP) mice underwent AH, CCl4 , and bile duct ligation (BDL) procedures to have comparable F1-F2 liver fibrosis. Col1a1-expressing cells were sorted via FACS by VitA autofluorescence and GFP for single-cell RNA sequencing. In AH, approximately 80% of Lrat+Thy1-Fbln2- activated HSCs were VitA-depleted (vs. ~13% in BDL and CCl4 ). Supervised clustering identified a subset co-expressing Lrat and Fbln2 (Lrat+Fbln2+), which expanded 44-fold, 17-fold, and 1.3-fold in AH, BDL, and CCl4 . Lrat+Fbln2+ cells had 3-15-times inductions of profibrotic, myofibroblastic, and immunoregulatory genes versus Lrat+Fbln2- cells, but 2-4-times repressed HSC-selective genes. AH activated HSCs had up-regulated inflammatory (chemokine [C-X-C motif] ligand 2 [Cxcl2], chemokine [C-C motif] ligand 2), antimicrobial (Il-33, Zc3h12a), and antigen presentation (H2-Q6, H2-T23) genes versus BDL and CCl4 . Computational deconvolution of AH versus normal human bulk-liver RNA-sequencing data supported an expansion of LRAT+FBLN2+ cells in AH; AH patient liver immunohistochemistry showed FBLN2 staining along fibrotic septa enriched with LRAT+ cells; and in situ hybridization confirmed co-expression of FBLN2 with CXCL2 and/or human leukocyte antigen E in patient AH. Finally, HSC tracing in Lrat-Cre;Rosa26mTmG mice detected GFP+FBLN2+ cells in AH.A highly profibrotic, inflammatory, and immunoregulatory Lrat+Fbln2+ subpopulation emerges from HSCs in AH and may contribute to the inflammatory and immunoreactive nature of AH.
Tulessin, M;Sarker, RSJ;Griger, J;Leibing, T;Geraud, C;Weichert, W;Steiger, K;Mogler, C;
PMID: 35883572 | DOI: 10.3390/cells11142129
The investigation of hepatocarcinogenesis is a major field of interest in oncology research and rodent models are commonly used to unravel the pathophysiology of onset and progression of hepatocellular carcinoma. HCC is a highly vascularized tumor and vascular remodeling is one of the hallmarks of tumor progression. To date, only a few detailed data exist about the vasculature and vascular remodeling in rodent models used for hepatocarcinogenesis. In this study, the vasculature of HCC and the preneoplastic foci of alteration (FCA) of different mouse models with varying genetic backgrounds were comprehensively characterized by using immunohistochemistry (CD31, Collagen IV, αSMA, Desmin and LYVE1) and RNA in situ hybridization (VEGF-A). Computational image analysis was performed to evaluate selected parameters including microvessel density, pericyte coverage, vessel size, intratumoral vessel distribution and architecture using the Aperio ImageScope and Definiens software programs. HCC presented with a significantly lower number of vessels, but larger vessel size and increased coverage, leading to a higher degree of maturation, whereas FCA lesions presented with a higher microvessel density and a higher amount of smaller but more immature vessels. Our results clearly demonstrate that vascular remodeling is present and crucial in early stages of experimental hepatocarcinogenesis. In addition, our detailed characterization provides a strong basis for further angiogenesis studies in these experimental models.
Namineni S, O'Connor T, Faure-Dupuy S, Johansen P, Riedl T, Liu K, Xu H, Singh I, Shinde P, Li F, Pandyra A, Sharma P, Ringelhan M, Muschaweckh A, Borst K, Blank P, Lampl S, Durantel D, Farhat R, Weber A, Lenggenhager D, K�ndig TM, Staeheli P, Protzer U, Wohlleber D, Holzmann B, Binder M, Breuhahn K, Assmus LM, Nattermann J, Abdullah Z, Rolland M, Dejardin E, Lang PA, Lang KS, Karin M, Lucifora J, Kalinke U, Knolle PA, Heikenwalder M
PMID: 31954207 | DOI: 10.1016/j.jhep.2019.12.019
Hepatic innate immune control of viral infections has largely been attributed to Kupffer cells, the liver macrophages. However, also hepatocytes, the parenchymal cells of the liver, possess potent immunological functions in addition to their known metabolic functions. Owing to their abundance in the liver and known immunological functions, we aimed to investigate the direct anti-viral mechanisms employed by hepatocytes.
METHODS:
Using lymphocytic choriomeningitis virus (LCMV) as a model of liver infection, we first assessed the role of myeloid cells by depletion prior to infection. We investigated the role of hepatocyte-intrinsic innate immune signaling by infecting mice lacking canonical NF-?B signaling (IKK??Hep) specifically in hepatocytes. In addition, mice lacking hepatocyte-specific interferon-?/? signaling-(IFNAR?Hep), or interferon-?/? signaling in myeloid cells-(IFNAR?Myel) were infected.
RESULTS:
Here, we demonstrate that LCMV activates NF-?B signaling in hepatocytes. LCMV-triggered NF-?B activation in hepatocytes did not depend on Kupffer cells or TNFR1- but rather on TLR-signaling. LCMV-infected IKK??Hep livers displayed strongly elevated viral titers due to LCMV accumulation within hepatocytes, reduced interferon-stimulated gene (ISG) expression, delayed intrahepatic immune cell influx and delayed intrahepatic LCMV-specific CD8+ T-cell responses. Notably, viral clearance and ISG expression were also reduced in LCMV-infected primary hepatocytes lacking IKK?, demonstrating a hepatocyte-intrinsic effect. Similar to livers of IKK??Hep mice, enhanced hepatocytic LCMV accumulation was observed in livers of IFNAR?Hep, whereas IFNAR?Myel mice were able to control LCMV-infection. Hepatocytic NF-?B signaling was also required for efficient ISG induction in HDV-infected dHepaRG cells and interferon-?/?-mediated inhibition of HBV replication in vitro.
CONCLUSIONS:
Together, these data show that hepatocyte-intrinsic NF-?B is a vital amplifier of interferon-?/? signaling pivotal for early, strong ISG responses, influx of immune cells and hepatic viral clearance.
Journal of immunology (Baltimore, Md. : 1950)
McCarthy, WC;Sherlock, LG;Grayck, MR;Zheng, L;Lacayo, OA;Solar, M;Orlicky, DJ;Dobrinskikh, E;Wright, CJ;
PMID: 36946778 | DOI: 10.4049/jimmunol.2200900
Hepatic innate immune function plays an important role in the pathogenesis of many diseases. Importantly, a growing body of literature has firmly established the spatial heterogeneity of hepatocyte metabolic function; however, whether innate immune function is zonated remains unknown. To test this question, we exposed adult C57BL/6 mice to endotoxemia, and hepatic tissue was assessed for the acute phase response (APR). The zone-specific APR was evaluated in periportal and pericentral/centrilobular hepatocytes isolated using digitonin perfusion and on hepatic tissue using RNAscope and immunohistochemistry. Western blot, EMSA, chromatin immunoprecipitation, and immunohistochemistry were used to determine the role of the transcription factor NF-κB in mediating hepatic C-reactive protein (CRP) expression. Finally, the ability of mice lacking the NF-κB subunit p50 (p50-/-) to raise a hepatic APR was evaluated. We found that endotoxemia induces a hepatocyte transcriptional APR in both male and female mice, with Crp, Apcs, Fga, Hp, and Lbp expression being enriched in pericentral/centrilobular hepatocytes. Focusing our work on CRP expression, we determined that NF-κB transcription factor subunit p50 binds to consensus sequence elements present in the murine CRP promoter. Furthermore, pericentral/centrilobular hepatocyte p50 nuclear translocation is temporally associated with zone-specific APR during endotoxemia. Lastly, the APR and CRP expression is blunted in endotoxemic p50-/- mice. These results demonstrate that the murine hepatocyte innate immune response to endotoxemia includes zone-specific activation of transcription factors and target gene expression. These results support further study of zone-specific hepatocyte innate immunity and its role in the development of various disease states.
Bresciani, N;Demagny, H;Lemos, V;Pontanari, F;Li, X;Sun, Y;Li, H;Perino, A;Auwerx, J;Schoonjans, K;
PMID: 35714811 | DOI: 10.1016/j.jhep.2022.05.040
Transporters of the SLC25 mitochondrial carrier superfamily bridge cytoplasmic and mitochondrial metabolism by channeling metabolites across mitochondrial membranes and are pivotal for metabolic homeostasis. Despite their physiological relevance as gatekeepers of cellular metabolism, most of the SLC25 family members remain uncharacterized. We undertook a comprehensive tissue distribution analysis of all Slc25 family members across metabolic organs and identified SLC25A47 as a liver-specific mitochondrial carrier.We used a murine loss-of-function model to unravel the role of this transporter in mitochondrial and hepatic homeostasis. We performed extensive metabolic phenotyping and molecular characterization of newly generated Slc25a47hep-/- and Slc25a47-Fgf21hep-/- mice.Slc25a47hep-/- mice displayed a wide variety of metabolic abnormalities, as a result of sustained energy deficiency in the liver originating from impaired mitochondrial respiration in this organ. This mitochondrial phenotype was associated with an activation of the mitochondrial stress response (MSR) in the liver, and the development of fibrosis, which was exacerbated upon feeding a high-fat high-sucrose diet. The MSR induced the secretion of several mitokines, amongst which FGF21 played a preponderant role on systemic physiology. To dissect the FGF21-dependent and -independent physiological changes induced in Slc25a47hep-/- mice, we generated a double Slc25a47-Fgf21hep-/- mouse model and demonstrated that several aspects of the hypermetabolic state were driven by hepatic secretion of FGF21. On the other hand, the metabolic fuel inflexibility observed in Slc25a47hep-/- mice could not be rescued with the genetic removal of Fgf21.Collectively, our data place SLC25A47 at the center of mitochondrial homeostasis, which upon dysfunction triggers robust liver-specific and systemic adaptive stress responses. The prominent role of SLC25A47 in hepatic fibrosis identifies this carrier, or its transported metabolite, as a potential target for therapeutic intervention.SLC25A47 is a liver-specific mitochondrial carrier. Slc25a47hep-/- mice are unable to maintain mitochondrial homeostasis in hepatocytes and show impaired mitochondrial respiration resulting in chronic energy deficiency, mitochondrial stress, and fibrosis in hepatocytes. Hepatic mitochondrial stress is characterized by the secretion of the mitokine FGF21 which drives a strong and systemic hypermetabolic state impacting whole-body physiology.
March-Riera, S;Wilson, AA;Bhatia, SN;Muhlberger, E;
| DOI: 10.1016/j.stemcr.2022.08.003
Liver damage and an exacerbated inflammatory response are hallmarks of Ebola virus (EBOV) infection. Little is known about the intrinsic response to infection in human hepatocytes and their contribution to inflammation. Here, we present an induced pluripotent stem cell (iPSC)-derived hepatocyte-like cell (HLC) platform to define the hepato-intrinsic response to EBOV infection. We used this platform to show robust EBOV infection, with characteristic ultrastructural changes and evidence for viral replication. Transcriptomics analysis revealed a delayed response with minimal early transcriptomic changes, followed by a general downregulation of hepatic function and upregulation of interferon signaling, providing a potential mechanism by which hepatocytes participate in disease severity and liver damage. Using RNA-fluorescence in situ hybridization (FISH), we showed that IFNB1 and CXCL10 were mainly expressed in non-infected bystander cells. We did not observe an inflammatory signature during infection. In conclusion, iPSC-HLCs are an immune competent platform to study responses to EBOV infection.
Chen, Z;He, Q;Lu, T;Wu, J;Shi, G;He, L;Zong, H;Liu, B;Zhu, P;
PMID: 36849569 | DOI: 10.1038/s41467-023-36651-5
Liver tumour-initiating cells (TICs) contribute to tumour initiation, metastasis, progression and drug resistance. Metabolic reprogramming is a cancer hallmark and plays vital roles in liver tumorigenesis. However, the role of metabolic reprogramming in TICs remains poorly explored. Here, we identify a mitochondria-encoded circular RNA, termed mcPGK1 (mitochondrial circRNA for translocating phosphoglycerate kinase 1), which is highly expressed in liver TICs. mcPGK1 knockdown impairs liver TIC self-renewal, whereas its overexpression drives liver TIC self-renewal. Mechanistically, mcPGK1 regulates metabolic reprogramming by inhibiting mitochondrial oxidative phosphorylation (OXPHOS) and promoting glycolysis. This alters the intracellular levels of α-ketoglutarate and lactate, which are modulators in Wnt/β-catenin activation and liver TIC self-renewal. In addition, mcPGK1 promotes PGK1 mitochondrial import via TOM40 interactions, reprogramming metabolism from oxidative phosphorylation to glycolysis through PGK1-PDK1-PDH axis. Our work suggests that mitochondria-encoded circRNAs represent an additional regulatory layer controlling mitochondrial function, metabolic reprogramming and liver TIC self-renewal.