Erica Novo

Università degli Studi di Torino, Torino, Piedmont, Italy

Are you Erica Novo?

Claim your profile

Publications (61)186.21 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Background & Aimsn-3 polyunsaturated fatty acids (PUFA) ameliorate fatty liver in experimental models, but their effects on inflammation and fibrosis during steatohepatitis are either controversial or lacking. We compared the effects of supplementation with olive oil (OO) alone or OO and n-3 PUFA on the development and progression of experimental steatohepatitis.Methods Balb/C mice (≥5 mice/group) were fed a methionine- and choline-deficient (MCD) diet or a control diet for 4 or 8 weeks. At the same time, mice were supplemented with n-3 PUFA (eicosapentaenoic and docosahexahenoic acid, 25 mg together with 75 mg OO), or OO alone (100 mg), two times a week by intragastric gavage.ResultsAfter 8 weeks, mice on MCD/n-3 had higher ALT levels compared to MCD/OO and more severe scores of inflammation, including a significant increase in the number of lipogranulomas (26.4 ± 8.4 vs. 5.1 ± 5 per field, P < 0.001). Intrahepatic expression of TNF-α and CCL2 was higher in MCD/n-3 mice at both time points. In addition, increased expression of the profibrogenic genes TIMP-1 and TGF-β, and more severe histological scores of fibrosis were evident in MCD/n-3 mice. After 8 week of MCD diet, portal pressure was higher in mice receiving n-3 than in those on OO alone (5.1 ± 1.4 vs. 7.0 ± 0.9 mmHg, P < 0.05). Analysis of hepatic fatty acid profile showed that supplementation resulted in effective incorporation of n-3 PUFA.Conclusions In a murine model of steatohepatitis, supplementation with n-3 PUFA and OO is associated with more severe necro-inflammation and fibrosis than in mice treated with OO only.
    Liver international: official journal of the International Association for the Study of the Liver 03/2014; · 3.87 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Liver fibrogenesis is a dynamic and highly integrated molecular, tissue and cellular process, potentially reversible, that drives the progression of chronic liver diseases (CLD) towards liver cirrhosis and hepatic failure. Hepatic myofibroblasts (MFs), the pro-fibrogenic effector cells, originate mainly from activation of hepatic stellate cells and portal fibroblasts being characterized by a proliferative and survival attitude. MFs also contract in response to vasoactive agents, sustain angiogenesis and recruit and modulate activity of cells of innate or adaptive immunity. Chronic activation of wound healing and oxidative stress as well as derangement of epithelial–mesenchymal interactions are “major” pro-fibrogenic mechanisms, whatever the etiology. However, literature has outlined a complex network of pro-fibrogenic factors and mediators proposed to modulate CLD progression, with some of them being at present highly debated in the field, including the role of epithelial to mesenchymal transition and Hedgehog signaling pathways. Hypoxia and angiogenesis as well as inflammasomes are recently emerged as ubiquitous pro-inflammatory and pro-fibrogenic determinants whereas adipokines are mostly involved in CLD related to metabolic disturbances (metabolic syndrome and/or obesity and type 2 diabetes). Finally, autophagy as well as natural killer and natural killer-T cells have been recently proposed to significantly affect fibrogenic CLD progression.
    Archives of Biochemistry and Biophysics 01/2014; · 3.37 Impact Factor
  • Digestive and Liver Disease. 01/2014; 46:e1.
  • [show abstract] [hide abstract]
    ABSTRACT: Fibrogenic progression of chronic liver diseases (CLDs) towards the end-point of cirrhosis is currently regarded, whatever the aetiology, as a dynamic and highly integrated cellular response to chronic liver injury. Liver fibrogenesis (i.e., the process) is sustained by hepatic populations of highly proliferative, pro-fibrogenic and contractile myofibroblast-like cells (MFs) that mainly originate from hepatic stellate cells (HSC) or, to a less extent, from portal fibroblasts or bone marrow-derived cells. As is well known, liver fibrosis (i.e., the result) is accompanied by perpetuation of liver injury, chronic hepatitis and persisting activation of tissue repair mechanisms, leading eventually to excess deposition of extracellular matrix (ECM) components. In this scenario, hypoxic areas represent a very common and major feature of fibrotic and cirrhotic liver during the progression of CLDs. Cells exposed to hypoxia respond by means of heterodimeric hypoxia-inducible factors (HIFs) that translocate into the nucleus and binds to a specific core sequence defined hypoxia-responsive element (HRE), present in the promoter on several genes which are considered as hypoxia-regulated target genes. HIFs transcription factors can activate a complex genetic program designed to sustain several changes necessary to efficiently counteract the decrease in oxygen tension. Accordingly, hypoxia, through up-regulation of angiogenesis, is currently believed to significantly contribute to fibrogenic progression of CLDs, mostly by affecting the pro-fibrogenic and pro-angiogenic behaviour of hepatic MFs. In addition, experimental and clinical evidence generated in the last decade also indicates that angiogenesis and fibrogenesis in CLDs may also be sustained by HIF-dependent but hypoxia-independent mediators.
    Histology and histopathology 09/2013; · 2.28 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Expression of CCL2 (CC chemokine ligand 2) (or monocyte chemoattractant protein-1) regulates inflammatory cell infiltration in the liver and adipose tissue, favouring steatosis. However, its role in the pathogenesis of steatohepatitis is still uncertain. In the present study, we investigated the development of non-alcoholic steatohepatitis induced by an MCD diet (methionine/choline-deficient diet) in mice lacking the CCL2 gene on two different genetic backgrounds, namely Balb/C and C57/Bl6J. WT (wild-type) and CCL2-KO (knockout) mice were fed on a lipid-enriched MCD diet or a control diet for 8 weeks. In Balb/C mice fed on the MCD diet, a lack of CCL2 was associated with lower ALT (alanine transaminase) levels and reduced infiltration of inflammatory cells, together with a lower generation of oxidative-stress-related products. Sirius Red staining demonstrated pericellular fibrosis in zone 3, and image analysis showed a significantly lower matrix accumulation in CCL2-KO mice. This was associated with reduced hepatic expression of TGF-β (transforming growth factor-β), type I procollagen, TIMP-1 (tissue inhibitor of metalloproteinases-1) and α-smooth muscle actin. In contrast, in mice on a C57Bl/6 background, neither ALT levels nor inflammation or fibrosis were significantly different comparing WT and CCL2-KO animals fed on an MCD diet. In agreement, genes related to fibrogenesis were expressed to comparable levels in the two groups of animals. Comparison of the expression of several genes involved in inflammation and repair demonstrated that IL (interleukin)-4 and the M2 marker MGL-1 (macrophage galactose-type C-type lectin 1) were differentially expressed in Balb/C and C57Bl/6 mice. No significant differences in the degree of steatosis were observed in all groups of mice fed on the MCD diet. We conclude that, in experimental murine steatohepatitis, the effects of CCL2 deficiency are markedly dependent on the genetic background.
    Clinical Science 04/2012; 123(7):459-71. · 4.86 Impact Factor
  • Source
    01/2012; , ISBN: 978-953-307-985-1
  • [show abstract] [hide abstract]
    ABSTRACT: Liver fibrogenesis is sustained by pro-fibrogenic myofibroblast-like cells (MFs), mainly originating from activated hepatic stellate cells (HSC/MFs) or portal (myo)fibroblasts, and is favoured by hypoxia-dependent angiogenesis. Human HSC/MFs were reported to express vascular-endothelial growth factor (VEGF) and VEGF-receptor type 2 and to migrate under hypoxic conditions. This study was designed to investigate early and delayed signalling mechanisms involved in hypoxia-induced migration of human HSC/MFs. Signal transduction pathways and intracellular generation of reactive oxygen species (ROS) were evaluated by integrating morphological, cell, and molecular biology techniques. Non-oriented and oriented migration were evaluated by using wound healing assay and the modified Boyden's chamber assay, respectively. The data indicate that hypoxia-induced migration of HSC/MFs is a biphasic process characterized by the following sequence of events: (a) an early (15 min) and mitochondria-related increased generation of intracellular ROS which (b) was sufficient to switch on activation of ERK1/2 and JNK1/2 that were responsible for the early phase of oriented migration; (c) a delayed and HIF-1α-dependent increase in VEGF expression (facilitated by ROS) and its progressive, time-dependent release in the extracellular medium that (d) was mainly responsible for sustained migration of HSC/MFs. Finally, immunohistochemistry performed on HCV-related fibrotic/cirrhotic livers revealed HIF-2α and haem-oxygenase-1 positivity in hepatocytes and α-SMA-positive MFs, indicating that MFs were likely to be exposed in vivo to both hypoxia and oxidative stress. In conclusion, hypoxia-induced migration of HSC/MFs involves an early, mitochondrial-dependent ROS-mediated activation of ERK and JNK, followed by a delayed- and HIF-1α-dependent up-regulation and release of VEGF.
    The Journal of Pathology 09/2011; 226(4):588-97. · 7.59 Impact Factor
  • Source
    C Busletta, E Novo, M Parola
    Hepatology International 07/2011; · 2.64 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Hypoxic conditions have been reported to facilitate preservation of undifferentiated mesenchymal stem cell (MSC) phenotype and positively affect their colony-forming potential, proliferation, and migration/mobilization. In this study, designed to dissect mechanisms underlying hypoxia-dependent migration of bone marrow-derived human MSC (hMSC), signal transduction, and molecular mechanisms were evaluated by integrating morphological, molecular, and cell biology techniques, including the wound healing assay (WHA) and modified Boyden's chamber assay (BCA) to monitor migration. Exposure of hMSCs to moderate hypoxia resulted in a significant increase of migration of hMSCs in both WHA (from 6 to 20 hours) and BCA (within 6 hours). Mechanistic experiments outlined the following sequence of hypoxia-dependent events: (a) very early (15 minutes) increased generation of intracellular reactive oxygen species (ROS), which (b) was sufficient to switch on activation of extracellular regulated kinase 1/2 and c-Jun N-terminal protein kinase 1/2, found to be relevant for the early phase of hMSC migration; (c) hypoxia inducible factor-1 (HIF-1)-dependent increased expression of vascular endothelial growth factor (VEGF) (facilitated by ROS) and its progressive release that was responsible for (d) a delayed and sustained migration of hMSCs. These results suggest that hypoxia-dependent migration relies on a previously unrecognized biphasic scenario involving an early phase, requiring generation of ROS, and a delayed phase sustained by HIF-1-dependent expression and release of VEGF.
    Stem Cells 06/2011; 29(6):952-63. · 7.70 Impact Factor
  • Journal of Hepatology - J HEPATOL. 01/2011; 54.
  • Journal of Hepatology - J HEPATOL. 01/2011; 54.
  • [show abstract] [hide abstract]
    ABSTRACT: Leptin modulates the angiogenic properties of hepatic stellate cells (HSC), but the molecular mechanisms involved are poorly understood. We investigated the pathways regulating hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) in leptin-stimulated myofibroblastic HSC. Exposure to leptin enhanced the phosphorylation of TSC2 on T1462 residues and of p70 S6 kinase and the translational inhibitor 4E-binding protein-1, indicating the ability of leptin to activate the mammalian target of rapamycin (mTOR) pathway. Similar findings were observed when HSC were exposed to PDGF. Both leptin and PDGF increased the expression of HIF-1α and VEGF in HSC. In the presence of rapamycin, a specific mTOR inhibitor, leptin and PDGF were no longer able to activate mTOR, and expression of VEGF was reduced, whereas HIF-1α abundance was not affected. Moreover, knockdown of Raptor, a component of the mTORC1 complex, reduced the ability of leptin to increase VEGF. mTOR was also necessary for leptin- and PDGF-dependent increase in HSC migration. Leptin increased the generation of reactive oxygen species in HSC, which was reduced by NADP(H) oxidase inhibitors. Both N-acetyl cysteine and diphenylene iodonium, a NADP(H) inhibitor, inhibited the expression of HIF-1α and VEGF stimulated by leptin or PDGF. Finally, conditioned media from HSC treated with leptin or PDGF induced tube formation in cultured human umbilical vein endothelial cells. In conclusion, in HSC exposed to leptin or PDGF, increased expression of VEGF requires both activation of mTOR and generation of reactive oxygen species via NADPH-oxidase. Induction of HIF-1α requires NADP(H) oxidase but not mTOR activation.
    AJP Gastrointestinal and Liver Physiology 01/2011; 301(2):G210-9. · 3.65 Impact Factor
  • Journal of Hepatology - J HEPATOL. 01/2011; 54.
  • Digestive and Liver Disease - DIG LIVER DIS. 01/2011; 43.
  • Digestive and Liver Disease - DIG LIVER DIS. 01/2011; 43.
  • [show abstract] [hide abstract]
    ABSTRACT: Liver fibrogenesis is sustained by myofibroblast-like cells originating from hepatic stellate cells (HSC/MFs), portal fibroblasts or bone marrow-derived cells, including mesenchymal stem cells (MSCs). Herein, we investigated the mechanistic role of intracellular generation of reactive oxygen species (ROS) and redox-sensitive signal transduction pathways in mediating chemotaxis, a critical profibrogenic response for human HSC/MFs and for MSC potentially engrafting chronically injured liver. Intracellular generation of ROS and signal transduction pathways were evaluated by integrating morphological and molecular biology techniques. Chemokinesis and chemotaxis were evaluated by wound healing assay and modified Boyden's chamber assay, respectively. Additional in vivo evidence was obtained in human specimens from HCV-related cirrhosis. Human MSCs and HSC/MFs migrate in response to a panel of polypeptide chemoattractants and extracellularly generated superoxide anion. All polypeptides induced a NADPH-oxidase-dependent intracellular rise in ROS, resulting in activation of ERK1/2 and JNK1/2. Moreover, menadione or 2,3-dimethoxy-1,4-naphthoquinone, which generate intracellular superoxide anion or hydrogen peroxide, respectively, induced ERK1/2 and JNK1/2 activation and migration. JNK1 activation was predominant for migration as shown by specific silencing. Finally, activation of ERK1/2 and JNK1/2 was found in extracts obtained from HSC/MFs during the course of an oxidative stress-mediated model of liver injury and phosphorylated JNK1/2 isoforms were detected in α-smooth muscle actin-positive myofibroblasts lining fibrotic septa in human cirrhotic livers. Intracellular generation of ROS, through activation of specific signaling pathways, is a critical event for directional migration of HSC/MFs and MSCs.
    Journal of Hepatology 10/2010; 54(5):964-74. · 9.86 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: We have investigated the presence and the possible clinical implications of oxidative stress in children with non-alcoholic fatty liver disease (NAFLD). The present study was an observational study of oxidative stress parameters in the progression of paediatric NAFLD. We observed the role of oxidative stress in children diagnosed with NAFLD by evaluating: serum protein carbonyls, hepatic expression of 8-hydroxy-2-deoxyguanosine (8-OHG), and circulating antibody against malondialdehyde adducted human serum albumin (MDA-HSA). Forty consecutive children with biopsy-proven NAFLD (27 male; 13 female) referred to Bambino Gesù Children's Hospital, Rome, Italy, from January 2007 to April 2008 were included in the study. Serum variations of protein carbonyls, 8-OHG, and circulating antibody against MDA-HSA were evaluated. Elevated protein carbonyls were evident in 33 subjects (83%) irrespective of obesity and insulin resistance. Moreover, liver biopsies of NAFLD patients positive for circulating protein carbonyls also showed a significant increase in the nuclear staining for 8-OHG (p=0.006; 95% CI 3.1-17.7). Anti-MDA-HSA IgG above control threshold was detected in 25 (63%) children. Although protein carbonyl levels were unrelated with disease severity, patients with elevated anti-MDA-HSA IgG had scores for lobular inflammation significantly higher (p=0.019) than subjects with antibodies within the control range, while steatosis, hepatocyte ballooning and fibrosis were similar. High anti-MDA-HSA reactivity was also associated with a 13-fold increased risk (OR=12.9; 95= CI 1.5-113.8; p=0.013) of a NAFLD activity score (NAS) >or=5. These results demonstrate that oxidative stress has an high prevalence in children with NAFLD and is associated with an increased severity of steatohepatitis.
    International Journal of Molecular Medicine 10/2010; 26(4):471-6. · 1.96 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: In any chronic liver disease (CLDs), whatever the aetiology, reiteration of liver injury results in persisting inflammation and progressive fibrogenesis, with chronic activation of the wound healing response in CLDs, representing a major driving force for progressive accumulation of ECM components, eventually leading to liver cirrhosis. Cirrhosis is characterized by fibrous septa dividing the hepatic parenchyma into regenerative pseudo-lobules, as well as by extensive changes in vascular architecture, the development of portal hypertension and related complications. Liver fibrogenesis (i.e., the dynamic process leading to increased deposition of ECM and much more) can lead to different patterns of fibrosis and is sustained by myofibroblast-like cells (MFs) of different origin, with activated hepatic stellate cells (HSC/MFs) being the major cell type involved. Major pro-fibrogenic mechanisms also include oxidative stress, as well as derangement of epithelial-mesenchymal interactions and, as recently suggested, the process of epithelial to mesenchymal transition (EMT). Liver fibrosis has been considered traditionally as an irreversible process but experimental and clinical literature data published in the last decade have suggested that both the removal of the aetiological agent or condition, as well as an effective therapy, can result in significant regression of liver fibrosis. This is usually associated, particularly in animal models, with induction of apoptosis in MFs but, unfortunately, human HSC/MFs are much more resistant to apoptosis than murine MFs. However, clinical studies provided no unequivocal evidence for a complete reversal of cirrhosis or a significant reversal of vascular changes in conditions of established cirrhosis.
    Histology and histopathology 08/2010; 25(8):1075-91. · 2.28 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Angiogenesis is a dynamic, hypoxia-stimulated and growth factor-dependent process, and is currently referred to as the formation of new vessels from pre-existing blood vessels. Experimental and clinical studies have unequivocally reported that hepatic angiogenesis, irrespective of aetiology, occurs in conditions of chronic liver diseases (CLDs) characterized by perpetuation of cell injury and death, inflammatory response and progressive fibrogenesis. Angiogenesis and related changes in liver vascular architecture, that in turn concur to increase vascular resistance and portal hypertension and to decrease parenchymal perfusion, have been proposed to favour fibrogenic progression of the disease towards the end-point of cirrhosis. Moreover, hepatic angiogenesis has also been proposed to modulate the genesis of portal-systemic shunts and increase splanchnic blood flow, thus potentially affecting complications of cirrhosis. Hepatic angiogenesis is also crucial for the growth and progression of hepatocellular carcinoma. Recent literature has identified a number of cellular and molecular mechanisms governing the cross-talk between angiogenesis and fibrogenesis, with a specific emphasis on the crucial role of hypoxic conditions and hepatic stellate cells, particularly when activated to the myofibroblast-like pro-fibrogenic phenotype. Experimental anti-angiogenic therapy has been proven to be effective in limiting the progression of CLDs in animal models. From a clinical point of view, anti-angiogenic therapy is currently emerging as a new pharmacologic intervention in patients with advanced fibrosis and cirrhosis.
    World Journal of Gastroenterology 01/2010; 16(3):281-8. · 2.55 Impact Factor
  • Journal of Hepatology - J HEPATOL. 01/2010; 52.