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Non-alcoholic fatty liver disease ranges from steatosis to non-alcoholic steatohepatitis (NASH), potentially progressing to cirrhosis and hepatocellular carcinoma (HCC). Here, we show that platelet number, platelet activation and platelet aggregation are increased in NASH but not in steatosis or insulin resistance. Antiplatelet therapy (APT; aspirin/clopidogrel, ticagrelor) but not nonsteroidal anti-inflammatory drug (NSAID) treatment with sulindac prevented NASH and subsequent HCC development. Intravital microscopy showed that liver colonization by platelets depended primarily on Kupffer cells at early and late stages of NASH, involving hyaluronan-CD44 binding. APT reduced intrahepatic platelet accumulation and the frequency of platelet-immune cell interaction, thereby limiting hepatic immune cell trafficking. Consequently, intrahepatic cytokine and chemokine release, macrovesicular steatosis and liver damage were attenuated. Platelet cargo, platelet adhesion and platelet activation but not platelet aggregation were identified as pivotal for NASH and subsequent hepatocarcinogenesis. In particular, platelet-derived GPIbα proved critical for development of NASH and subsequent HCC, independent of its reported cognate ligands vWF, P-selectin or Mac-1, offering a potential target against NASH.

Significance JNK signaling has been studied intensively in models of liver physiology and disease, but previous studies had focused on young mice. However, it had not been recognized that JNK plays a fundamental role in maintaining liver homeostasis and preventing the formation of biliary cysts in aging mice. These observations call for caution in all long-term pharmacological inhibition strategies targeting the JNK pathway. Finally, our results provide evidence of a molecular link between JNK and the cell-death mediator RIPK1. The specific overexpression of RIPK1 in cysts of a subset of patients with polycystic liver disease suggests that RIPK1 might be mechanistically involved in the pathogenesis of human biliary cysts., The c-Jun N-terminal kinase (JNK) signaling pathway mediates adaptation to stress signals and has been associated with cell death, cell proliferation, and malignant transformation in the liver. However, up to now, its function was experimentally studied mainly in young mice. By generating mice with combined conditional ablation of Jnk1 and Jnk2 in liver parenchymal cells (LPCs) (JNK1/2LPC-KO mice; KO, knockout), we unraveled a function of the JNK pathway in the regulation of liver homeostasis during aging. Aging JNK1/2LPC-KO mice spontaneously developed large biliary cysts that originated from the biliary cell compartment. Mechanistically, we could show that cyst formation in livers of JNK1/2LPC-KO mice was dependent on receptor-interacting protein kinase 1 (RIPK1), a known regulator of cell survival, apoptosis, and necroptosis. In line with this, we showed that RIPK1 was overexpressed in the human cyst epithelium of a subset of patients with polycystic liver disease. Collectively, these data reveal a functional interaction between JNK signaling and RIPK1 in age-related progressive cyst development. Thus, they provide a functional linkage between stress adaptation and programmed cell death (PCD) in the maintenance of liver homeostasis during aging.

Mucosal barrier immunity is essential for the maintenance of the commensal microflora and combating invasive bacterial infection. Although immune and epithelial cells are thought to be the canonical orchestrators of this complex equilibrium, here, we show that the enteric nervous system (ENS) plays an essential and non-redundant role in governing the antimicrobial protein (AMP) response. Using confocal microscopy and single-molecule fluorescence in situ mRNA hybridization (smFISH) studies, we observed that intestinal neurons produce the pleiotropic cytokine IL-18. Strikingly, deletion of IL-18 from the enteric neurons alone, but not immune or epithelial cells, rendered mice susceptible to invasive Salmonella typhimurium (S.t.) infection. Mechanistically, unbiased RNA sequencing and single-cell sequencing revealed that enteric neuronal IL-18 is specifically required for homeostatic goblet cell AMP production. Together, we show that neuron-derived IL-18 signaling controls tissue-wide intestinal immunity and has profound consequences on the mucosal barrier and invasive bacterial killing. © 2019 Elsevier Inc., Cell, 180 (1), ISSN:0092-8674, ISSN:1097-4172

Recent studies suggest that clear cell renal cell carcinoma (ccRCC) possesses a rare population of cancer stem cells (CSCs) that might contribute to tumor heterogeneity, metastasis and therapeutic resistance. Nevertheless, their relevance for renal cancer is still unclear. In this study, we successfully isolated CSCs from established human ccRCC cell lines. CSCs displayed high expression of the chemokine IL‐8 and its receptor CXCR1. While recombinant IL‐8 significantly increased CSC number and properties in vitro, CXCR1 inhibition using an anti‐CXCR1 antibody or repertaxin significantly reduced these features. After injection into immune‐deficient mice, CSCs formed primary tumors that metastasized to the lung and liver. All xenografted tumors in mice expressed high levels of IL‐8 and CXCR1. Furthermore, IL‐8/CXCR1 expression significantly correlated with decreased overall survival in ccRCC patients. These results suggest that the IL‐8/CXCR1 phenotype is associated with CSC‐like properties in renal cancer. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland., Journal of Pathology, 248 (3), ISSN:0022-3417, ISSN:1096-9896

Background & Aims Intestinal epithelial homeostasis depends on a tightly regulated balance between intestinal epithelial cell (IEC) death and proliferation. While the disruption of several IEC death regulating factors result in intestinal inflammation, the loss of the anti-apoptotic BCL2 family members BCL2 and BCL2L1 has no effect on intestinal homeostasis in mice. We investigated the functions of the antiapoptotic protein MCL1, another member of the BCL2 family, in intestinal homeostasis in mice. Methods We generated mice with IEC-specific disruption of Mcl1 (Mcl1ΔIEC mice) or tamoxifen-inducible IEC-specific disruption of Mcl1 (i-Mcl1ΔIEC mice); these mice and mice with full-length Mcl1 (controls) were raised under normal or germ-free conditions. Mice were analyzed by endoscopy and for intestinal epithelial barrier permeability. Intestinal tissues were analyzed by histology, in situ hybridization, proliferation assays, and immunoblots. Levels of calprotectin, a marker of intestinal inflammation, were measured in intestinal tissues and feces. Results Mcl1ΔIEC mice spontaneously developed apoptotic enterocolopathy, characterized by increased IEC apoptosis, hyperproliferative crypts, epithelial barrier dysfunction, and chronic inflammation. Loss of MCL1 retained intestinal crypts in a hyperproliferated state and prevented the differentiation of intestinal stem cells. Proliferation of intestinal stem cells in MCL1-deficient mice required WNT signaling and was associated with DNA damage accumulation. By 1 year of age, Mcl1ΔIEC mice developed intestinal tumors with morphologic and genetic features of human adenomas and carcinomas. Germ-free housing of Mcl1ΔIEC mice reduced markers of microbiota-induced intestinal inflammation but not tumor development. Conclusion The antiapoptotic protein MCL1, a member of the BCL2 family, is required for maintenance of intestinal homeostasis and prevention of carcinogenesis in mice. Loss of MCL1 results in development of intestinal carcinomas, even under germ-free conditions, and therefore does not involve microbe-induced chronic inflammation. Mcl1ΔIEC mice might be used to study apoptotic enterocolopathy and inflammatory bowel diseases., Graphical abstract

Hepatocellular carcinoma (HCC) represents a classic example of inflammation-linked cancer. To characterize the role of the immune system in hepatic injury and tumor development, we comparatively studied the extent of liver disease and hepatocarcinogenesis in immunocompromised versus immunocompetent Fah-deficient mice. Strikingly, chronic liver injury and tumor development were markedly suppressed in alymphoid Fah(-/-) mice despite an overall increased mortality. Mechanistically, we show that CD8(+) Tcells and lymphotoxin βare central mediators of HCC formation. Antibody-mediated depletion of CD8(+) Tcells as well as pharmacological inhibition of the lymphotoxin-β receptor markedly delays tumor development in mice with chronic liver injury. Thus, our study unveils distinct functions of the immune system, which are required for liver regeneration, survival, and hepatocarcinogenesis.

The immune suppressive and anti-inflammatory capabilities of bone marrow-derived mesenchymal stromal cells (MSCs) represent an innovative new tool in regenerative medicine and immune regulation. The potent immune suppressive ability of MSC over T cells, dendritic cells, and natural killer cells has been extensively characterized, however, the effect of MSC on B cell function has not yet been clarified. In this study, the direct effect of MSC on peripheral blood B cell function is defined and the mechanism utilized by MSC in enhancing B cell survival in vitro identified. Human MSC supported the activation, proliferation, and survival of purified CD19(+) B cells through a cell contact-dependent mechanism. These effects were not mediated through B cell activating factor or notch signaling. However, cell contact between MSC and B cells resulted in increased production of vascular endothelial growth factor (VEGF) by MSC facilitating AKT phosphorylation within the B cell and inhibiting caspase 3-mediated apoptosis. Blocking studies demonstrated that this cell contact-dependent effect was not dependent on signaling through CXCR4-CXCL12 or through the epidermal growth factor receptor (EGFR). These results suggest that direct cell contact between MSC and B cells supports B cell viability and function, suggesting that MSC may not represent a suitable therapy for B cell-mediated disease.

Members of the Burkholderia cepacia complex (Bcc) cause chronic opportunistic lung infections in people with cystic fibrosis (CF), resulting in a gradual lung function decline and, ultimately, patient death. The Bcc is a complex of 20 species and is rarely eradicated once a patient is colonized; therefore, vaccination may represent a better therapeutic option. We developed a new proteomics approach to identify bacterial proteins that are involved in the attachment of Bcc bacteria to lung epithelial cells. Fourteen proteins were reproducibly identified by two-dimensional gel electrophoresis from four Bcc strains representative of two Bcc species: Burkholderia cenocepacia , the most virulent, and B. multivorans , the most frequently acquired. Seven proteins were identified in both species, but only two were common to all four strains, linocin and OmpW. Both proteins were selected based on previously reported data on these proteins in other species. Escherichia coli strains expressing recombinant linocin and OmpW showed enhanced attachment (4.2- and 3.9-fold) to lung cells compared to the control, confirming that both proteins are involved in host cell attachment. Immunoproteomic analysis using serum from Bcc-colonized CF patients confirmed that both proteins elicit potent humoral responses in vivo . Mice immunized with either recombinant linocin or OmpW were protected from B. cenocepacia and B. multivorans challenge. Both antigens induced potent antigen-specific antibody responses and stimulated strong cytokine responses. In conclusion, our approach identified adhesins that induced excellent protection against two Bcc species and are promising vaccine candidates for a multisubunit vaccine. Furthermore, this study highlights the potential of our proteomics approach to identify potent antigens against other difficult pathogens.

International audience; Glucagon and thyroid hormone (T3) exhibit therapeutic potential for metabolic disease but also exhibit undesired effects. We achieved synergistic effects of these two hormones and mitigation of their adverse effects by engineering chemical conjugates enabling delivery of both activities within one precisely targeted molecule. Coordinated glucagon and T3 actions synergize to correct hyperlipidemia, steatohepatitis, atherosclerosis, glucose intolerance, and obesity in metabolically compromised mice. We demonstrate that each hormonal constituent mutually enriches cellular processes in hepatocytes and adipocytes via enhanced hepatic cholesterol metabolism and white fat browning. Synchronized signaling driven by glucagon and T3 reciprocally minimizes the inherent harmful effects of each hormone. Liver-directed T3 action offsets the diabetogenic liability of glucagon, and glucagon-mediated delivery spares the cardiovascular system from adverse T3 action. Our findings support the therapeutic utility of integrating these hormones into a single molecular entity that offers unique potential for treatment of obesity, type 2 diabetes, and cardiovascular disease.

Mutations that result in loss of function of Nod2, an intracellular receptor for bacterial peptidoglycan, are associated with Crohn’s disease. Here we found that the E3 ubiquitin ligase Pellino3 was an important mediator in the Nod2 signaling pathway. Pellino3-deficient mice had less induction of cytokines after engagement of Nod2 and had exacerbated disease in various experimental models of colitis. Furthermore, expression of Pellino3 was lower in the colons of patients with Crohn’s disease. Pellino3 directly bound to the kinase RIP2 and catalyzed its ubiquitination. Loss of Pellino3 led to attenuation of Nod2-induced ubiquitination of RIP2 and less activation of the transcription factor NF-kB and mitogen-activated protein kinases (MAPKs). Our findings identify RIP2 as a substrate for Pellino3 and Pellino3 as an important mediator in the Nod2 pathway and regulator of intestinal inflammation.

Summary Acute graft-versus-host disease (aGVHD) is a life-threatening complication following allogeneic haematopoietic stem cell transplantation (HSCT), occurring in up to 30–50% of patients who receive human leucocyte antigen (HLA)-matched sibling transplants. Current therapies for steroid refractory aGVHD are limited, with the prognosis of patients suboptimal. Mesenchymal stem or stromal cells (MSC), a heterogeneous cell population present in many tissues, display potent immunomodulatory abilities. Autologous and allogeneic ex-vivo expanded human MSC have been utilized to treat aGVHD with promising results, but the mechanisms of therapeutic action remain unclear. Here a robust humanized mouse model of aGVHD based on delivery of human peripheral blood mononuclear cells (PBMC) to non-obese diabetic (NOD)-severe combined immunodeficient (SCID) interleukin (IL)-2rγnull (NSG) mice was developed that allowed the exploration of the role of MSC in cell therapy. MSC therapy resulted in the reduction of liver and gut pathology and significantly increased survival. Protection was dependent upon the timing of MSC therapy, with conventional MSC proving effective only after delayed administration. In contrast, interferon (IFN)-γ-stimulated MSC were effective when delivered with PBMC. The beneficial effect of MSC therapy in this model was not due to the inhibition of donor PBMC chimerism, as CD45+ and T cells engrafted successfully in this model. MSC therapy did not induce donor T cell anergy, FoxP3+ T regulatory cells or cause PBMC apoptosis in this model; however, it was associated with the direct inhibition of donor CD4+ T cell proliferation and reduction of human tumour necrosis factor-α in serum.