Genetic modification is critically enabling for studies addressing specification and maintenance of cell fate, however methods for engineering modifications are inefficient. We demonstrate a rapid and efficient recombination system in which an inducible, floxed cre allele replaces itself with an incoming transgene. We target this inducible cassette exchange (ICE) allele to the HPRT locus, and demonstrate recombination in murine embryonic stem (ES) cells and primary cells from derivative ICE mice. Using lentivectors, we demonstrate recombination at a randomly integrated ICE locus in human ES cells. To illustrate the utility of this system, we insert the myogenic regulator, Myf5, into the ICE locus in each platform. This enables efficient directed differentiation of mouse and human ES cells into skeletal muscle, and conditional myogenic transdetermination of primary cells cultured in vitro. This versatile tool is thus well suited to gain-of-function studies probing gene function in the specification and reprogramming of cell fate.

Background & Aims Interleukin-15 (IL-15) and its high affinity receptor interleukin-15 receptor alpha (IL-15Rα) are widely expressed in immune cells and hepatic resident cells. IL-15 signaling has important functions in homeostasis of natural killer (NK), natural killer T (NKT) and cytotoxic T (CD8+T) cells, and in liver regeneration. We hypothesized that IL-15 has a protective role in liver fibrosis progression by maintaining NK cell homeostasis. Methods Fibrosis was induced using two mechanistically distinct models. Congenic bone marrow transplantation was used to evaluate the contribution of IL-15 signaling from various compartments to NK, CD8+T and NKT cell homeostasis and fibrogenesis. The gene expression profile of hepatic stellate cell (HSC) from IL-15Rα knockout (IL-15RαKO) mice and wild type mice were captured using microarray analysis and validated in isolated HSC. Quantitative real-time PCR was used to assess repressors of collagen transcription. Results IL-15RαKO mice exhibited more fibrosis in both models. IL-15 signaling from specific types of hepatic cells had divergent roles in maintaining liver NK, CD8+T and NKT cells, with a direct and protective role on radio-resistant non-parenchymal cells beyond the control of NK homeostasis. HSCs isolated from IL-15RαKO mice demonstrated up-regulation of collagen production. Finally, IL-15RαKO HSC with or without transforming growth factor beta (TGF-β) stimulation exhibited increased expression of fibrosis markers and decreased collagen transcription repressors expression. Conclusions IL-15Rα signaling has a direct anti-fibrotic effect independent of preserving NK homeostasis. These findings establish a rationale to further explore the anti-fibrotic potential of enhancing IL-15 signaling in HSCs.

Murine models of chronic alcohol consumption are frequently used to investigate alcoholic liver injury and define new therapeutic targets. Lieber-DeCarli diet (LD) and Meadows-Cook diet (MC) are the most accepted models of chronic alcohol consumption. It is unclear how similar these models are at the cellular, immunologic, and transcriptome levels. We investigated the common and specific pathways of LD and MC models. Livers from LD and MC mice were subjected to histologic changes, hepatic leukocyte population, hepatic transcripts level related to leukocyte recruitment, and hepatic RNA-seq analysis. Cross-species comparison was performed using the alcoholic liver disease (ALD) transcriptomic public dataset. Despite LD mice have increased liver injury and steatosis by alcohol exposure, the number of CD45 + cells were reduced. Opposite, MC mice have an increased number of monocytes/liver by alcohol. The pattern of chemokine gradient, adhesion molecules, and cytokine transcripts is highly specific for each model, not shared with advanced human alcoholic liver disease. Moreover, hepatic RNA-seq revealed a limited and restricted number of shared genes differentially changed by alcohol exposure in these 2 models. Thus, mechanisms involved in alcohol tissue injury are model-dependent at multiple levels and raise the consideration of significant pathophysiological diversity of human alcoholic liver injury. Murine models are frequently used to investigate new pathophysiological pathways of human diseases and many new treatment trials for alcoholic liver disease (ALD) are based on preclinical testing provided by murine models. ALD in humans is the result of a complex interaction between the alcoholic effects on gut microbiota, intestinal cells, immune system, and the hepatic microenvironment 1,2. Based on an extensive body of literature, alcohol increases the intestinal permeability and subsequent systemic translocation of bacterial products, e.g. LPS 1,3,4. Stimulation of Toll-like receptors (TLR) by bacterial products results in immune cell activation related to hepatic alcohol metabolic process that has a deleterious effect on the liver, resulting in histological features of ALD: steatosis, innate immune infiltrate with predominance of neutrophils and monocytes, and histological signs of hepatocyte dysfunction (Mallory hyaline formation, ballooning hepatocyte) 3,5-7. ALD includes a spectrum of histological and clinical entities: steatosis, steatohepatitis, and alcoholic hepatitis 8,9. In time, chronic liver injury with a dysregulated innate immune response results in alcohol-induced progressive hepatic fibrogenesis, liver cirrhosis and end-stage liver disease 10. Based on this classical paradigm, few trials have been attempted to control an exacerbated innate immune response or to improve hepatocyte function. Besides steroids that may be beneficial for only subsets of patients with alcoholic hepatitis 11 , no other treatments have proven consistent survival benefit 12. Moreover, treatment of anti-TNFα in alcoholic hepati...

SELDI-TOF-MS technology combined with protein pattern analysis seems a valuable approach for the identification of liver cirrhosis and hepatocellular carcinoma in patients with chronic hepatitis C. Most probably a combination of different serum markers will help to identify liver cirrhosis and early-stage hepatocellular carcinomas in the future.

It is now about 40 years ago that the mechanism of renal 1-α-hydroxylation of vitamin D was discovered and characterized. After this seminal observation, the key role of the active vitamin D derivative 1, 25-(OH)2-vitamin D (calcitriol) in calcium homeostasis and bone mineralization, and its specific role in the course of chronic kidney disease (CKD) and renal osteopathy, was unraveled step by step, while the precursor 25-OH-vitamin D (calcidiol) was gradually ignored. Calcitriol and its synthetic analogue alfa-calcidol became the first-line standard drug to tackle secondary hyperparathyroidism (sHPT) in CKD. Potential side-effects, including hypercalcemia, hyperphosphatemia, and vascular calcification, were partly abrogated by developing less calcemic substances such as paricalcitol or maxacalcitol. Thus, TIME Magazine surprised when nominating vitamin D, with regard to its newly discovered pleiotropic actions, as one of the "top medical breakthroughs" in the December issue of 2007. This vote was driven by novel and spectacular insights into the pivotal regulatory role of vitamin D with regard to autoimmune diseases, immune defense, cancer development and progression, and cardiovascular function and disease. More than 30 cell types express the vitamin D receptor (VDR), and more than ten organs in addition to the kidney are capable of paracrine 1-α-hydroxylation. More than 200 genes are under the control of calcitriol. A MEDLINE search performed in December 2009 focusing on the keywords "vitamin D-and-kidney-and-2009" yielded 523 hits. This review intends to give a subjective and CKD-related update on novel biological and clinical insights with relevance to the steroid hormone vitamin D.

The aim of this study was to investigate the role of osteopontin (OPN) in hematopoietic stem cell (HPSC) mobilization to the liver and its contribution to alcoholic liver disease (ALD). We analyzed young (14‐16 weeks) and old (>1.5 years) wild‐type (WT) littermates and global Opn knockout (Opn−/−) mice for HPSC mobilization to the liver. In addition, WT and Opn−/− mice were chronically fed the Lieber–DeCarli diet for 7 weeks. Bone marrow (BM), blood, spleen, and liver were analyzed by flow cytometry for HPSC progenitors and polymorphonuclear neutrophils (PMNs). Chemokines, growth factors, and cytokines were measured in serum and liver. Prussian blue staining for iron deposits and naphthol AS‐D chloroacetate esterase staining for PMNs were performed on liver sections. Hematopoietic progenitors were lower in liver and BM of young compared to old Opn−/− mice. Granulocyte colony‐stimulating factor and macrophage colony‐stimulating factor were increased in Opn−/− mice, suggesting potential migration of HPSCs from the BM to the liver. Furthermore, ethanol‐fed Opn−/− mice showed significant hepatic PMN infiltration and hemosiderin compared to WT mice. As a result, ethanol feeding caused greater liver injury in Opn−/− compared to WT mice. Conclusion: Opn deletion promotes HPSC mobilization, PMN infiltration, and iron deposits in the liver and thereby enhances the severity of ALD. The age‐associated contribution of OPN to HPSC mobilization to the liver, the prevalence of PMNs, and accumulation of hepatic iron, which potentiates oxidant stress, reveal novel signaling mechanisms that could be targeted for therapeutic benefit in patients with ALD. (Hepatology Communications 2018;2:84–98)

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Monocytes develop in the bone marrow from the hematopoietic stem cells and represent heterogeneous phagocyte cells in the circulation. In homeostatic and inflammatory conditions, after recruitment into tissues, monocytes differentiate into macrophages and dendritic cells. Alcohol use causes about 3.3 million worldwide deaths per year, which is about 5.9% of all deaths. In the United States and Europe, alcohol use disorders represent the fifth leading cause of death. Females are more susceptible to alcoholic liver injury in both humans and mice. Strikingly, we still do not know how much of this difference in tissue injury is due to the differential effect of alcohol and its toxic metabolites on a) parenchymal or resident cells and/or b) immune response to alcohol. Therefore, we used a model of chronic alcohol exposure in mice to investigate the dynamics of monocytes, an innate immune cell type showed to be critical in alcoholic liver injury, by using immunophenotypic characterization. Our data reveal a sex-dimorphism of alcohol response of hepatic monocytes in female mice that is interferon receptor alpha dependent. This dimorphism could shed light on potential cellular mechanism(s) to explain the susceptibility of females to alcoholic immunopathogenesis and suggests an additional targetable pathway for alcoholic liver injury in females.