Clonal exhaustion as a mechanism to protect against severe immunopathology and death from an overwhelming CD8 T cell response

The balance between protective immunity and immunopathology often determines the fate of the virus-infected host. How rapidly virus is cleared is a function of initial viral load, viral replication rate, and efficiency of the immune response. Here, we demonstrate, with three different inocula of lymphocytic choriomeningitis virus (LCMV), how the race between virus replication and T cell responses can result in different disease outcomes. A low dose of LCMV generated efficient CD8 T effector cells, which cleared the virus with minimal lung and liver pathology. A high dose of LCMV resulted in clonal exhaustion of T cell responses, viral persistence, and little immunopathology. An intermediate dose only partially exhausted the T cell responses and resulted in significant mortality, and the surviving mice developed viral persistence and massive immunopathology, including necrosis of the lungs and liver. This suggests that for non-cytopathic viruses like LCMV, hepatitis C virus, and hepatitis B virus, clonal exhaustion may be a protective mechanism preventing severe immunopathology and death

Liver carcinogenesis by FOS-dependent inflammation and cholesterol dysregulation

233294Human hepatocellular carcinomas (HCCs), which arise on a background of chronic liver damage and inflammation, express c-Fos, a component of the AP-1 transcription factor. Using mouse models, we show that hepatocyte-specific deletion of c-Fos protects against diethylnitrosamine (DEN)-induced HCCs, whereas liver-specific c-Fos expression leads to reversible premalignant hepatocyte transformation and enhanced DEN-carcinogenesis. c-Fos-expressing livers display necrotic foci, immune cell infiltration, and altered hepatocyte morphology. Furthermore, increased proliferation, dedifferentiation, activation of the DNA damage response, and gene signatures of aggressive HCCs are observed. Mechanistically, c-Fos decreases expression and activity of the nuclear receptor LXRα, leading to increased hepatic cholesterol and accumulation of toxic oxysterols and bile acids. The phenotypic consequences of c-Fos expression are partially ameliorated by the anti-inflammatory drug sulindac and largely prevented by statin treatment. An inverse correlation between c-FOS and the LXRα pathway was also observed in human HCC cell lines and datasets. These findings provide a novel link between chronic inflammation and metabolic pathways important in liver cancer.We thank Drs. N. Djouder, M. Petruzzelli, R. Ricci, F.X Real, K.D. Bissig, and members of the Wagner laboratory for critical reading of the manuscript and valuable sugges- tions; Dr. H. Schönthaler for help with the bioinformatics analysis; V. Bermeo for technical help; and G. Luque, S. Leceta, and G. Medrano for assisting with mouse experiments. The E.F. Wagner laboratory is supported by grants from the Spanish Ministry of Economy, Industry, and Competitiveness (BFU2012-40230 and SAF2015-70857, co- funded by the European Regional Development Fund), a European Research Council– advanced grant (ERC-FCK/2008/37), and Worldwide Cancer Research (13-0216). R. Hamacher was supported by the Deutsche Forschungsgemeinschaft (HA 6068/1-1), M.K. Thomsen by AUFF Nova, and S.C. Hasenfuss by a Boehringer Ingelheim Fonds PhD fellowship. The authors declare no competing financial interests. Author contributions: L. Bakiri and R. Hamacher designed and performed exper- iments, analyzed data, prepared figures, and wrote the manuscript. O. Graña analyzed RNA-seq and public microarray data, A. Guío-Carrión provided expert technical assis- tance, R. Campos-Olivas acquired and analyzed NMR data, L. Martinez analyzed flow cytometry data, M.K. Thomsen performed experiments with human cell lines, S.C. Hasenfuss performed experiments with primary hepatocytes and data mining, and H.P. Dienes performed pathological analysis on tissue sections. E.F. Wagner directed the study, approved the data, and wrote and edited the paper. All authors read and commented on the manuscript.S

Consensus Recommendations for Histological Criteria of Autoimmune Hepatitis from the International AIH Pathology Group

Background & Aims Diagnostic histological criteria for autoimmune hepatitis (AIH) have not been clearly established. Previously published criteria focused mainly on chronic AIH, in which inflammatory changes mainly occur in portal/periportal regions and may not be applicable to acute presentation of AIH, in which inflammatory changes are typically predominantly lobular in location. International consensus criteria for the diagnosis and assessment of disease severity in both acute and chronic AIH are thus urgently needed. Methods Seventeen expert liver pathologists convened at an international workshop and subsequently used a modified Delphi panel approach to establish consensus criteria for the histopathological diagnosis of AIH. Results The consensus view is that liver biopsy should remain standard for diagnosing AIH. AIH is considered likely, if there is a predominantly portal lymphoplasmacytic hepatitis with more than mild interface activity and/or more than mild lobular hepatitis in the absence of histological features suggestive of another liver disease. AIH is also considered likely if there is predominantly lobular hepatitis with or without centrilobular necroinflammation and at least one of the following features: portal lymphoplasmacytic hepatitis, interface hepatitis or portal-based fibrosis, in the absence of histological features suggestive of another liver disease. Emperipolesis and hepatocellular rosettes are not regarded as being specific for AIH. Conclusions The criteria proposed in this consensus statement provide a uniform approach to the histological diagnosis of AIH, which is relevant for patients with an acute as well as a chronic presentation and to more accurately reflect the current understanding of liver pathology in AIH

Hepatocyte Growth Factor (HGF) Inhibits Collagen I and IV Synthesis in Hepatic Stellate Cells by miRNA-29 Induction

BACKGROUND: In chronic liver disease, hepatic stellate cells (HSC) transdifferentiate into myofibroblasts, promoting extracellular matrix (ECM) synthesis and deposition. Stimulation of HSC by transforming growth factor-β (TGF-β) is a crucial event in liver fibrogenesis due to its impact on myofibroblastic transition and ECM induction. In contrast, hepatocyte growth factor (HGF), exerts antifibrotic activities. Recently, miR-29 has been reported to be involved in ECM synthesis. We therefore studied the influence of HGF and TGF-β on the miR-29 collagen axis in HSC. METHODOLOGY: HSC, isolated from rats, were characterized for HGF and Met receptor expression by Real-Time PCR and Western blotting during culture induced myofibroblastic transition. Then, the levels of TGF-β, HGF, collagen-I and -IV mRNA, in addition to miR-29a and miR-29b were determined after HGF and TGF-β stimulation of HSC or after experimental fibrosis induced by bile-duct obstruction in rats. The interaction of miR-29 with 3'-untranslated mRNA regions (UTR) was analyzed by reporter assays. The repressive effect of miR-29 on collagen synthesis was studied in HSC treated with miR-29-mimicks by Real-Time PCR and immunoblotting. PRINCIPAL FINDINGS: The 3'-UTR of the collagen-1 and -4 subtypes were identified to bind miR-29. Hence, miR-29a/b overexpression in HSC resulted in a marked reduction of collagen-I and -IV synthesis. Conversely, a decrease in miR-29 levels is observed during collagen accumulation upon experimental fibrosis, in vivo, and after TGF-β stimulation of HSC, in vitro. Finally, we show that during myofibroblastic transition and TGF-β exposure the HGF-receptor, Met, is upregulated in HSC. Thus, whereas TGF-β stimulation leads to a reduction in miR-29 expression and de-repression of collagen synthesis, stimulation with HGF was definitely associated with highly elevated miR-29 levels and markedly repressed collagen-I and -IV synthesis. CONCLUSIONS: Upregulation of miRNA-29 by HGF and downregulation by TGF-β take part in the anti- or profibrogenic response of HSC, respectively

Studies for Estimating the Biologic Behavior and Prognosis of Paragangliomas in the Head and Neck

Despite a large number of histopathologic and immunohistochemical studies, the biologic behavior and prognosis of paragangliomas (glomus tumors) of the head and neck still remain uncertain. In the present study 36 specimens from 32 patients who underwent surgery for a paraganglioma were examined. The examinations included routine histology, quantitative DNA analysis based on image cytometry, immunohistochemical detection of the proliferating cell nuclear antigen (PCNA) along with visualization of nucleolar organizer regions (AgNOR). According to LeCompte, the paragangliomas were histologically divided into three subcategories: 16 patients had a paragangliomatous tumor. 14 patients had an adenomatous tumor, and 6 patients had an angiomatous tumor. Quantitative DNA analysis revealed three categories of tumors with characteristical DNA pattern; DNA type I tumors were pure diploid, DNA type II tumors had stemlines at 2c and 4c and were therefore recognized as diploid-tetraploid. Aneuploid cells were not apparent in these two groups. DNA type III tumors had stemline ploidies exceeding 2c and 4c. Aneuploid cells were present in all of these tumors. The biologic behavior of these lesions therefore must be recognized as suspicious. DNA type III tumors and adenomatous tumors showed the highest values for the PCNA scores, indicating a higher proliferation rate and a more rapid growth pattern in these lesions. Twenty patients could be followed over a period of up to 110 months. Five of these patients developed a recurrent tumor. All of them had DNA type III tumors. The DNA indices showed significantly higher values in the recurrent tumor group. The 2c deviation index (DI) and the entropy value had the highest prognostic significance. No correlation to clinical follow-up was found for the AgNOR score. Based on these results, prognostic indices for paragangliomas were developed: patients with a tumor having a 2c DI exceeding 2.0, entropy value of more than 4.0. 5c exceeding rate more than 8.0, and a PCNA score more than 20.0% can be recognized as being at high-risk for developing recurrent disease

Nuclear translocation of beta-catenin and decreased expression of epithelial cadherin in human papillomavirus-positive tonsillar cancer: an early event in human papillomavirus-related tumour progression?

International audienceAims: High-risk human papillomaviruses (HPV) seem to be an important risk factor for tonsillar cancer. However, only few data exist concerning molecular changes during metastasis. Methods and Results: We examined 48 primary tonsillar carcinoma samples (25 HPV-16 DNA positive, 23 HPV-16 DNA negative) and their respective lymph node metastases for their HPV status and for the expression of p16, E-cadherin, β-catenin and vimentin. A positive HPV-specific PCR correlated significantly with p16 overexpression in both the primary tumor and metastasis (p<0.0001 both). In HPV-unrelated patients the expression of E-cadherin was significantly less abundant in metastases than in primary tumors (p<0.001). The expression of nuclear β-catenin was contrariwise significantly higher in metastases than in primary tumors (p=0.016). Compared to HPV-unrelated patients, in HPV-related ones the nuclear localisation of β-catenin expression was already apparent in primary tumors (p=0.030). The expression of vimentin significantly correlated with the grading of the primary tumor (p=0.021). Conclusions: Our data newly indicate that the downregulation of E-cadherin together with an upregulation of nuclear β-catenin might be crucial steps during tumor progression of tonsillar cancer being already present in primary tumors in HPV driven cancers but become apparent in HPV-unrelated tumors later during the process of metastasizing