Background & AimsThe lack of a preclinical model of progressive non-alcoholic steatohepatitis (NASH) that recapitulates human disease is a barrier to therapeutic development.MethodsA stable isogenic cross between C57BL/6J (B6) and 129S1/SvImJ (S129) mice were fed a high fat diet with ad libitum consumption of glucose and fructose in physiologically relevant concentrations and compared to mice fed a chow diet and also to both parent strains.ResultsFollowing initiation of the obesogenic diet, B6/129 mice developed obesity, insulin resistance, hypertriglyceridemia and increased LDL-cholesterol. They sequentially also developed steatosis (4–8 weeks), steatohepatitis (16–24 weeks), progressive fibrosis (16 weeks onwards) and spontaneous hepatocellular cancer (HCC). There was a strong concordance between the pattern of pathway activation at a transcriptomic level between humans and mice with similar histological phenotypes (FDR 0.02 for early and 0.08 for late time points). Lipogenic, inflammatory and apoptotic signaling pathways activated in human NASH were also activated in these mice. The HCC gene signature resembled the S1 and S2 human subclasses of HCC (FDR 0.01 for both). Only the B6/129 mouse but not the parent strains recapitulated all of these aspects of human NAFLD.ConclusionsWe here describe a diet-induced animal model of non-alcoholic fatty liver disease (DIAMOND) that recapitulates the key physiological, metabolic, histologic, transcriptomic and cell-signaling changes seen in humans with progressive NASH.Lay summaryWe have developed a diet-induced mouse model of non-alcoholic steatohepatitis (NASH) and hepatic cancers in a cross between two mouse strains (129S1/SvImJ and C57Bl/6J). This model mimics all the physiological, metabolic, histological, transcriptomic gene signature and clinical endpoints of human NASH and can facilitate preclinical development of therapeutic targets for NASH.

iPSCs, and iPSC-EVs were injected intramyocardially at 48 hours after a reperfused myocardial infarction in mice. Compared with vehicle-injected mice, both iPSC-and iPSC-EV-treated mice exhibited improved left ventricular function at 35 d after myocardial infarction, albeit iPSC-EVs rendered greater improvement. iPSC-EV injection also resulted in reduction in left ventricular mass and superior perfusion in the infarct zone.Both iPSCs and iPSC-EVs preserved viable myocardium in the infarct zone, whereas reduction in apoptosis was significant with iPSC-EVs. iPSC injection resulted in teratoma formation, whereas iPSC-EV injection was safe. Conclusions: iPSC-derived

Recent observational studies in humans suggest that circulating FGF23 is independently associated with cardiac hypertrophy and increased mortality, but it is unknown whether FGF23 can directly alter cardiac function. We found that FGF23 significantly increased cardiomyocyte cell size in vitro, the expression of gene markers of cardiac hypertrophy, and total protein content of cardiac muscle. In addition, FGFR1 and FGFR3 mRNA were the most abundantly expressed FGF receptors in cardiomyocytes, and the coreceptor ␣-klotho was expressed at very low levels. We tested an animal model of chronic kidney disease (Col4a3 Ϫ/Ϫ mice) that has elevated serum FGF23. We found elevations in common hypertrophy gene markers in Col4a3 Ϫ/Ϫ hearts compared with wild type but did not observe changes in wall thickness or cell size by week 10. However, the Col4a3 Ϫ/Ϫ hearts did show reduced fractional shortening (Ϫ17%) and ejection fraction (Ϫ11%). Acute exposure of primary cardiomyocytes to FGF23 resulted in elevated intracellular Ca 2ϩ ([Ca 2ϩ ]i; F/Fo ϩ 86%) which was blocked by verapamil pretreatment. FGF23 also increased ventricular muscle strip contractility (67%), which was inhibited by FGF receptor antagonism. We hypothesize that although FGF23 can acutely increase [Ca 2ϩ ]i, chronically this may lead to decreases in contractile function or stimulate cardiac hypertrophy, as observed with other stress hormones. In conclusion, FGF23 is a novel bone/heart endocrine factor and may be an important mediator of cardiac Ca 2ϩ regulation and contractile function during chronic kidney disease. fibroblast growth factor 23; pathological cardiac hypertrophy; chronic kidney disease; Col4a3; cardiac function; ␣-klotho FIBROBLAST GROWTH FACTOR 23 (FGF23) is a hormone released primarily by osteocytes (2, 4, 14, 38) that functions to regulate phosphate and vitamin D homeostasis through direct actions on the kidney and parathyroid (2). Although an endocrine axis has been established between bone and kidney, a new paradigm is emerging in which FGF23 could be important in establishing an endocrine axis between bone and heart. Circulating levels of FGF23 are markedly elevated 100-to 1,000-fold in patients with chronic kidney disease (CKD) (24, 31) and are independently associated with cardiovascular morbidity and mortality (8,22,26,34,35,48,52). Specifically, an association between left ventricular (LV) hypertrophy and serum FGF23 levels has been established in CKD patients (20,36,52).Nevertheless, despite strong associations between FGF23 and adverse outcomes, it remains relatively unknown whether FGF23 is simply a marker of cardiac disease risk or a direct mediator of cardiac pathology and cardiac performance. Only one study to date has analyzed the direct effects of FGF23 on the heart both in vitro and in vivo (13). This important work by Faul et al. (13) shows that FGF23 can directly induce hypertrophy in isolated neonatal cardiomyocytes as well as with intramyocardial FGF23 injections. These authors also demonstrated that a FGF receptor (FGF...

Rationale The role of interleukin (IL)-6 in the pathogenesis of cardiac myocyte hypertrophy remains controversial. Objective To conclusively determine whether IL-6 signaling is essential for the development of pressure overload-induced left ventricular (LV) hypertrophy, and to elucidate the underlying molecular pathways. Methods and Results Wild-type (WT) and IL-6 knockout (IL-6−/−) mice underwent sham surgery or transverse aortic constriction (TAC) to induce pressure overload. Serial echocardiograms and terminal hemodynamic studies revealed attenuated LV hypertrophy and superior preservation of LV function in IL-6−/− mice after TAC. The extents of LV remodeling, fibrosis, and apoptosis were reduced in IL-6−/− hearts after TAC. Transcriptional and protein assays of myocardial tissue identified CaMKII and STAT3 activation as important underlying mechanisms during cardiac hypertrophy induced by TAC. The involvement of these pathways in myocyte hypertrophy was verified in isolated cardiac myocytes from WT and IL-6−/− mice exposed to pro-hypertrophy agents. Furthermore, overexpression of CaMKII in H9c2 cells increased STAT3 phosphorylation, and exposure of H9c2 cells to IL-6 resulted in STAT3 activation that was attenuated by CaMKII inhibition. Together these results identify the importance of CaMKII-dependent activation of STAT3 during cardiac myocyte hypertrophy via IL-6 signaling. Conclusions Genetic deletion of IL-6 attenuates TAC-induced LV hypertrophy and dysfunction, indicating a critical role played by IL-6 in the pathogenesis of LV hypertrophy in response to pressure overload. CaMKII plays an important role in IL-6-induced STAT3 activation and consequent cardiac myocyte hypertrophy. These findings may have significant therapeutic implications for LV hypertrophy and failure in patients with hypertension.

The heterogeneity of biological processes driving the severity of nonalcoholic fatty liver disease (NAFLD) as reflected in the transcriptome and the relationship between the pathways involved are not well established. Well-defined associations between gene expression profiles and disease progression would benefit efforts to develop novel therapies and to understand disease heterogeneity. We analyzed hepatic gene expression in controls and a cohort with the full histological spectrum of NAFLD. Protein-protein interaction and gene set variation analysis revealed distinct sets of coordinately regulated genes and pathways whose expression progressively change over the course of the disease. The progressive nature of these changes enabled us to develop a framework for calculating a disease progression score for individual genes. We show that, in aggregate, these scores correlate strongly with histological measures of disease progression and can thus themselves serve as a proxy for severity. Furthermore, we demonstrate that the expression levels of a small number of genes (~20) can be used to infer disease severity. Finally, we show that patient subgroups can be distinguished by the relative distribution of gene-level scores in specific gene sets. While future work is required to identify the specific disease characteristics that correspond to patient clusters identified on this basis, this work provides a general framework for the use of high-content molecular profiling to identify NAFLD patient subgroups.

ABSTRACT

Fibrosis, resulted from the imbalance of fibrogenesis and fibrolysis, is a key readout of disease progression in nonalcoholic steatohepatitis (NASH) and reflects mortality risk. Non-invasive biomarkers capable of diagnosing fibrosis stages and monitoring fibrosis changes in NASH patients are urgently needed. This study is to evaluate collagen formation and degradation biomarkers, reflective of fibrogenesis or fibrolysis, in patients with biopsy proven NASH. Collagen formation biomarker PRO-C3 and PRO-C6 levels were significantly higher in patients with advanced fibrosis stage 3–4 than those with fibrosis stage 0–2. Elevated PRO-C3 levels were also associated with severe lobular inflammation and ballooning, but not with steatosis. Multivariate logistic regression analysis identified PRO-C3 and PRO-C6 to be independently related to fibrosis stage. PRO-C3 showed similar performance to identify patients with advanced fibrosis in discovery and validation cohorts. Furthermore, in a longitudinal study cohort with paired biopsies, mean PRO-C3 increased with worsening of fibrosis and decreased with fibrosis improvement. The results suggest that PRO-C3 may be a potentially useful biomarker in identifying patients with advanced fibrosis and active fibrogenesis, as well as in assessing changes in fibrosis over time. It is worthy of further evaluation to confirm its diagnostic value and clinical utility.

Adult bone marrow-derived very small embryonic-like stem cells (VSEL-SCs) exhibit a Sca-1+/Lin–/CD45– phenotype and can differentiate into various cell types, including cardiomyocytes and endothelial cells. We have previously reported that transplantation of a small number (1 × 106) of freshly isolated, non-expanded VSEL-SCs into infarcted mouse hearts resulted in improved left ventricular (LV) function and anatomy. Clinical translation, however, will require large numbers of cells. Because the frequency of VSEL-SCs in the marrow is very low, we examined whether VSEL-SCs can be expanded in culture without loss of therapeutic efficacy. Mice underwent a 30 min. coronary occlusion followed by reperfusion and, 48 hrs later, received an intramyocardial injection of vehicle (group I, n= 11), 1 × 105 enhanced green fluorescent protein (EGFP)-labelled expanded untreated VSEL-SCs (group II, n= 7), or 1 × 105 EGFP-labelled expanded VSEL-SCs pre-incubated in a cardiogenic medium (group III, n= 8). At 35 days after myocardial infarction (MI), mice treated with pre-incubated VSEL-SCs exhibited better global and regional LV systolic function and less LV hypertrophy compared with vehicle-treated controls. In contrast, transplantation of expanded but untreated VSEL-SCs did not produce appreciable reparative benefits. Scattered EGFP+ cells expressing α-sarcomeric actin, platelet endothelial cell adhesion molecule (PECAM)-1, or von Willebrand factor were present in VSEL-SC-treated mice, but their numbers were very small. No tumour formation was observed. We conclude that VSEL-SCs expanded in culture retain the ability to alleviate LV dysfunction and remodelling after a reperfused MI provided that they are exposed to a combination of cardiomyogenic growth factors and cytokines prior to transplantation. Counter intuitively, the mechanism whereby such pre-incubation confers therapeutic efficacy does not involve differentiation into new cardiac cells. These results support the potential therapeutic utility of VSEL-SCs for cardiac repair.