Expression of insulin-like growth factor 1 and insulin-like growth factor 1 receptor and its intervention by interleukin-10 in experimental hepatic fibrosis

Mechanism of myocardial fibrosis regulation by IGF-1R in atrial fibrillation through the PI3K/Akt/FoxO3a pathway

Atrial structural remodeling takes on a critical significance to the occurrence and maintenance of atrial fibrillation (AF). As revealed by recent data, insulin-like growth factor-1 receptor (IGF-1R) plays a certain role in tissue fibrosis. In this study, the mechanism of IGF-1R in atrial structural remodeling was examined based on in vivo and in vitro experiments. First, cluster analysis of AF hub genes was conducted, and then the molecular mechanism was proposed by which IGF-1R regulates myocardial fibrosis via the PI3K/Akt/FoxO3a pathway. Subsequently, the mentioned mechanism was verified in human cardiac fibroblasts (HCFs) and rats transduced with IGF-1 overexpression type 9 adeno-associated viruses. The results indicated that IGF-1R activation up-regulated collagen Ⅰ protein expression and Akt phosphorylation in HCFs and rat atrium. The administration of LY294002 reversed the above phenomenon, improved the shortening of atrial effective refractory period, and reduced the increased incidence of AF and atrial fibrosis in rats. The transfection of FoxO3a siRNA reduced the anti-fibrotic effect of LY294002 in HCFs. The above data revealed that activation of IGF-1R takes on a vital significance to atrial structural remodeling by facilitating myocardial fibrosis and expediting the occurrence and maintenance of AF through the regulation of the PI3K/Akt/FoxO3a signaling pathway.

Hepatic IGF-1R overexpression combined with the activation of GSK-3β and FOXO3a in the development of liver cirrhosis

AIMS

Liver cirrhosis is the common pathological histology manifest among a number of chronic liver diseases and liver cancer. Circulating levels of insulin growth factor-1 (IGF-1) have been recently linked to liver cirrhosis and the development of liver cancer. Herein, we hypothesized that IGF-1R overexpression combining the activation of GSK-3β and FOXO3a were involved in the development of human and murine chronic liver cirrhosis.

METHODS

Liver samples of patients were screened from the Tissue Bank of the China-Japan Union Hospital of Jilin University. Mice liver fibrosis model was performed using intraperitoneal injection of carbon tetrachloride (CCl4) for 12weeks. Serum IGF-1 levels were detected by enzyme-linked immunosorbent assays (ELISA). Microscopical examination of liver parenchyma was performed using conventional H&E and Masson's staining. Moreover, we investigated the IGF-1 receptor (IGF-1R) signaling pathway at different period after CCl4 administration.

RESULTS

Serum IGF-1 levels were significantly decreased in patients with liver cirrhosis, which is concomitant with the declined circulating levels of IGF-1 in 8 to 12weeks CCl4-treated mice. Furthermore, the expression of IGF-1R was significantly higher at 12w compared with control group. In addition, activation of the GSK-3β and FOXO3a were activated during the process of murine chronic liver injury.

CONCLUSION

The present study demonstrates that decreased circulating IGF-1 levels are involved in human and murine chronic liver disease. Interestingly, overexpression of the IGF-1R, and activation of GSK3β and FOXO3a might be the molecular mechanisms underlying the development of liver cirrhosis.

Differential Expression of Ion Channels and Transporters During Hepatocellular Carcinoma Development

BACKGROUND

Ion channels and transporters are potential markers and therapeutic targets for several cancers. However, their expression during hepatocellular carcinoma (HCC) development remains unclear.

AIM

To investigate the mRNA expression of Na(+), K(+) and Ca(2+) channels and ABC transporters during rat HCC development, as well as Abcc3 protein in human liver biopsies.

METHODS

Wistar rats were treated with diethylnitrosamine (DEN) and developed both cirrhosis (12 weeks of treatment) and either pre-neoplastic lesions (16 weeks of treatment) or multinodular HCC (16 weeks of treatment plus 2 weeks DEN-free). The mRNA expression of 12 ion channels and two ABC transporters was studied using real-time RT-PCR. Tumor-containing or tumor-free liver sections were isolated by laser-capture microdissection. Abcc3 protein expression was studied by immunohistochemistry in healthy, cirrhotic and HCC human biopsies.

RESULTS

We observed expression changes in seven genes. Kcna3, Kcnn4, Kcnrg and Kcnj11 potassium channel mRNA expression reached peak values at the end of DEN treatment, while Scn2a1 sodium channel, Trpc6 calcium channel and Abcc3 transporter mRNA expression reached their highest levels in the presence of HCC (18 weeks). Whereas Kcnn4 and Scn2a1 channel expression was similar in non-tumor and tumor tissue, the Abcc3 transporter and Kcna3 potassium channels were preferentially overexpressed in the tumor sections. We observed differential Abcc3 protein subcellular localization and expression in human samples.

CONCLUSIONS

The ion channel/transporter expression profile observed suggests that these genes are potential early markers or therapeutic targets of HCC. The differential localization of Abcc3 may be useful in the diagnosis of cirrhosis and HCC.

Acute inflammation induces insulin-like growth factor-1 to mediate Bcl-2 and Muc5ac expression in airway epithelial cells

Generally, exposure to LPS in human airways occurs in the form of aerosols and causes an acute inflammatory response or exacerbates existing chronic inflammatory conditions by enhancing airway remodeling and associated pathologies. The present study evaluated which inflammatory mediators may be responsible for the expression of Bcl-2 and mucus cell metaplasia when mice are exposed to aerosolized LPS. At 3 days after exposure, aerosolized LPS (for 20-40 min) with the estimated lung deposited dosage of 0, 0.02, 0.2, 1.4, and 20.2 μg showed a characteristic dose-dependent increase in polymorphonuclear neutrophils. Significant increases of proinflammatory mediators, including IL-1β, TNF-α, IL-6, growth-related oncogene or keratinocyte-derived cytokine, IFN-γ-induced protein-10, monocyte chemotactic protein-1, and macrophage inflammatory protein-1α, were detected at the highest doses. In addition to increased numbers of airway epithelial cells, mucus cell numbers and mucus production were increased in a dose-dependent manner. Hyperplastic epithelial cells expressed insulin-like growth factor (IGF)-1 and, similar to previous studies, increased expression of the prosurvival protein Bcl-2 and induced expression of Muc5ac. Suppression of IGF-1 expression using retroviral shRNA blocked Bcl-2 expression in human and murine airway epithelial cells and Muc5ac in primary murine airway epithelial cells. These findings show that acute inflammation induces IGF-1 to mediate Bcl-2 and Muc5ac expression in airway epithelial cells.

IGF-1R contributes to stress-induced hepatocellular damage in experimental cholestasis

The insulin-like growth factor type 1 receptor (IGF-1R) controls aging and cellular stress, both of which play major roles in liver disease. Stimulation of insulin-like growth factor signaling can generate cell death in vitro. Here, we tested whether IGF-1R contributes to stress insult in the liver. Cholestatic liver injury was induced by bile duct ligation in control and liver-specific IGF-1R knockout (LIGFREKO) mice. LIGFREKO mice displayed less bile duct ligation-induced hepatocyte damage than controls, while no differences in bile acid serum levels or better adaptation to cholestasis by efflux transporters were found. We therefore tested whether stress pathways contributed to this phenomenon; oxidative stress, ascertained by both malondialdehyde content and heme oxygenase-1 expression, was similar in knockout and control animals. However, together with a lower level of eukaryotic initiation factor-2 alpha phosphorylation, the endoplasmic reticulum stress protein CHOP and its downstream pro-apoptotic target Bax were induced to lesser extents in LIGFREKO mice than in controls. Expression levels of cytokeratin 19, transforming growth factor-beta1, alpha-smooth muscle actin, and collagen alpha1(I) in LIGFREKO mice were all lower than in controls, indicating reduced ductular and fibrogenic responses and increased cholestasis tolerance in these mutants. This stress resistance phenotype was also evidenced by longer post-bile duct ligation survival in mutants than controls. These results indicate that IGF-1R contributes to cholestatic liver injury, and suggests the involvement of both CHOP and Bax in this process.

Etiopathogenesis of hepatic osteodystrophy in Wistar rats with cholestatic liver disease

The pathophysiology of hepatic osteodystrophy (HO) remains poorly understood. Our aim was to evaluate bone histomorphometry, biomechanical properties, and the role of the growth hormone (GH)/insulin-like growth factor-I (IGF-I) system in the onset of this disorder. Forty-six male Wistar rats were divided into two groups: sham-operated (SO, n = 23) and bile duct-ligated (BDL, n = 23). Rats were killed on day 30 postoperatively. Immunohistochemical expression of IGF-I and GH receptor was determined in liver tissue and in the proximal growth plate cartilage of the left tibia. Histomorphometric analysis was performed in the right tibia, and the right femur was used for biomechanical analysis. The maximal force at fracture and the stiffness of the mid-shaft femur were, respectively, 53% and 24% lower in BDL compared to SO. Histomorphometric measurements showed low cancellous bone volume and decreased cancellous bone connectivity in BDL, compatible with osteoporosis. This group also showed increased mineralization lag time, indicating disturbance in bone mineralization. Serum levels of IGF-I were lower in BDL (basal 1,816 +/- 336 vs. 30 days 1,062 +/- 191 ng/ml, P < 0.0001). BDL also showed higher IGF-I expression in the liver tissue but lower IGF-I and GH receptor expression in growth plate cartilage than SO. Osteoporosis is the most important feature of HO; BDL rats show striking signs of reduced bone volume and decreased bone strength, as early as after 1 month of cholestasis. The endocrine and autocrine-paracrine IGF-I systems are deeply affected by cholestasis. Further studies will be necessary to establish their role in the pathogenesis of HO.

Transplantation of urokinase-type plasminogen activator gene-modified bone marrow-derived liver stem cells reduces liver fibrosis in rats

BACKGROUND

Bone marrow-derived liver stem cells (BDLSCs) are very robust cells that can differentiate into liver epithelial cells. These stem cells are promising targets for gene therapy treatment of liver diseases. Liver fibrosis results from chronic liver damage characterized by an accumulation of extracellular matrix (ECM) and levels of urokinase-type plasminogen activator (uPA) play an important role in ECM degradation. In the present study, we investigated the therapeutic effects of uPA gene-modified BDLSC transplantation on carbon tetrachloride (CCl4)-induced liver fibrosis in rats.

METHODS

BDLSCs were obtained from the bone marrow of cholestatic rats. These stem cells were selected and proliferated in medium containing 5% cholestatic serum. BDLSCs transfected with adenovirus-mediated human urokinase-plasminogen activator were transplanted into rats with CCl(4)-induced hepatic fibrosis. Liver function and the area of hepatic fibrosis were correlated with the development and prognosis of hepatic fibrosis.

RESULTS

Hepatocyte-like colony-forming units were formed by bone marrow cells after 2 weeks in culture. In the uPA gene-modified BDLSC group, the areas of hepatic fibrosis were smaller and liver function was markedly ameliorated compared to controls. The expression of alpha-smooth muscle actin protein, transforming growth factor-beta1 protein and collagen types I and III mRNA were downregulated. By contrast, the levels of matrix metalloproteinases-2, -3 and -9 mRNA, hepatic growth factor mRNA and proliferating cell nuclear antigen protein increased.

CONCLUSIONS

Transplantation of uPA gene-modified BDLSCs may suppress hepatic fibrosis and ameliorate liver function.

Gene therapy for hepatic fibrosis

Hepatic fibrosis is a common pathological process of chronic liver diseases, characterized by increased synthesis and relatively low degradation of extracellular matrix (ECM) resulting from their dynamic imbalance. Recent progress in molecular biology techniques has made it possible to treat hepatic fibrosis with gene therapy. At present, the commonly used method is to induce the expression of exogenous genes by transducing enough therapeutic genes into injured liver to delay or cure liver fibrosis.

Increased hepatic expression of insulin-like growth factor-I receptor in chronic hepatitis C

AIM: Although increased insulin-like growth factor-I receptor (IGF-IR) gene expression has been reported in hepatocellular carcinoma, studies assessing IGF-IR in chronic hepatitis C (CHC) and cirrhosis are scarce. We therefore aimed to evaluate IGF-IR and IGF-I mRNA expression in liver from patient with CHC.

METHODS: IGF-IR and IGF-I mRNA content were determined by semi-quantitative RT-PCR and IGF-IR protein expression was determined by immunohisto-chemistry in hepatic tissue obtained from patients with CHC before (34 patients) and after (10 patients) therapy with interferon-α and ribavirin.

RESULTS: An increase of IGF-IR mRNA content was observed in hepatic tissue obtained from all CHC patients as well as from 6 cadaveric liver donors following orthopic transplantation (an attempt to evaluate normal livers) in comparison to normal liver, while no relevant modifications were detected in IGF-I mRNA content. The immunohistochemical results showed that the raise in IGF-IR mRNA content was related both to ductular reaction and to increased IGF-IR expression in hepatocytes. A decrease in IGF-IR mRNA content was observed in patients who achieved sustained virological response after therapy, suggesting an improvement in hepatic damage.

CONCLUSION: The up-regulation of IGF-IR expression in hepatocytes of patients with CHC could constitute an attempt to stimulate hepatocyte regeneration. Considering that liver is the organ with the highest levels of IGF-I, our finding of increased IGF-IR expression after both acute and chronic hepatic damage highlights the need for additional studies to elucidate the role of IGF-I in liver regeneration.

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Interleukin-10 and chronic liver disease

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Numerous investigations suggest that IL-10 plays a major role in chronic liver diseases. IL-10 gene polymorphisms are possibly associated with liver disease susceptibility or severity. Recombinant human IL-10 has been produced and is currently tested in clinical trials. These trials may give new insights into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Altered expression of type I insulin-like growth factor receptor in Crohn's disease

The fibrotic and antiapoptotic effects of insulin-like growth factors (IGF) are mediated by type I IGF receptor (IGF-1R). IGFs could play a role in intestinal stricturing and in the maintenance of inflammation in Crohn's disease (CD). We aimed to describe IGF-1R expression in CD intestinal lesions, to compare it to other intestinal inflammatory diseases and to correlate it with fibrosis and apoptosis. IGF-1R expression and apoptosis (active caspase-3) were studied by immunohistochemistry. Surgical intestinal specimens [17 CD, nine controls, six diverticulitis and four ulcerative colitis (UC)] were used. IGF-1R was expressed transmurally mainly by inflammatory cells (IC) and smooth muscle cells, both in diseased intestine and controls. IGF-1R positive IC were increased in the mucosa and the submucosa of CD (P < 0.007), and in involved areas compared to uninvolved areas (P = 0.03). In UC, the number of IGF-1R positive IC was only increased in the mucosa, and was not different from controls in the submucosa. In diverticulitis, the number of IGF-1R positive IC did not differ from controls. In CD submucosa, IGF-1R expression in IC was inversely correlated with apoptosis in uninvolved areas (P = 0.01). Expression of IGF-1R in submucosal fibroblast-like cells, subserosal adipocytes and hypertrophic nervous plexi was specific for CD. We have shown a transmural altered expression of IGF-1R in CD. This may suggest a role for IGF-1R in the maintenance of chronic inflammation and stricture formation in CD.

Systemic infusion of FLK1(+) mesenchymal stem cells ameliorate carbon tetrachloride-induced liver fibrosis in mice

BACKGROUND

Fibrosis is the common end stage of most liver diseases, for which, unfortunately, there is no effective treatment available currently. It has been shown that mesenchymal stem cells (MSCs) from bone marrow (BM) could engraft in the lung after bleomycin exposure and ameliorate its fibrotic effects. This study was designed to evaluate the effect of Flk1 MSCs from murine BM (termed here Flk1 mMSCs) on fibrosis formation induced by carbon tetrachloride (CCl4).

METHODS

A CCl(4)-induced hepatic fibrosis model was used. Flk1 mMSCs were systemically infused immediately or 1 week after mice were challenged with CCl(4). Control mice received only saline infusion. Fibrosis index and donor-cell engraftment were assessed 2 or 5 weeks after CCl(4) challenge.

RESULTS

We found that Flk1 mMSCs transplantation immediately, but not 1 week after exposure to CCl(4), significantly reduced CCl(4)-induced liver damage and collagen deposition. In addition, levels of hepatic hydroxyproline and serum fibrosis markers in mice receiving immediate Flk1 mMSCs transplantation after CCl(4) challenge were significantly lower compared with those of control mice. More importantly, histologic examination suggested that hepatic damage recovery was much better in these immediately Flk1 mMSCs-treated mice. Immunofluorescence, polymerase chain reaction, and fluorescence in situ hybridization analysis revealed that donor cells engrafted into host liver, had epithelium-like morphology, and expressed albumin, although at low frequency.

CONCLUSION

These results suggest that Flk1 mMSCs might initiate endogenous hepatic tissue regeneration, engraft into host liver in response to CCl(4) injury, and ameliorate its fibrogenic effects.

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Effects of different operations on cirrhotic portal hypertensive liver in rats

AIM: To evaluate respectively the effects of portaazygous disconnection (PAD), mesocaval shunt (MCS) and distal splenocaval shunt (DSCS) on the portasytemic shunting (PSS), hepatic function (HF), hepatic mitochondrial respiratory function (HMRF) and its ultrastructure, anti-oxidation ability (HAOA) and lipoperoxide (LPO), so as to provide theoretical basis to select a suitable operation.

METHODS: Using the cirrhotic portal hypertensive model induced by CCl₄/ethanol in Wristar rats, we investigated PSS, HF, HMRF and its HAOA and LPO during three wks after MCS, DSCS and PAD.

RESULTS: After MCS, the PSS were further increased, HF, HMRF and HAOA were significantly decreased, and LPO increased. Hepatic mitochondrial ultrastructure showed severely damaged. Only a little improvement was found on the third wk. After DSCS and PAD, above mentioned indexes were less influenced, and they were restored a little more quickly in DSCS groups than that in PAD groups. During the first postoperative wk, the PAD group showed the highest mortality.

CONCLUSION: DSCS may be a desirable operation among the three kinds of operation.

Gene expression profiles in liver cirrhosis and normal liver tissues

AIM: To describe liver specific gene expression profiles and to identify genes with differential expression between liver cirrhotic tissues and normal liver tissues.

METHODS: The cDNA probes which were labeled with α-³²P dATP were synthesized from total RNAs of liver cirrhosis and normal liver tissues and hybridized to two identical Atlas human cDNA expression arrays membranes containing 588 known genes respectively.

RESULTS: Autoradiographic results were analyzed by specific AtlasImage^TM (version1.01a) software. Among the 588 genes analyzed, 17 genes were found up-regulated in cirrhosis, including integrin beta 7 and collagen type XVIII, and 98 genes were down-regulated in cirrhosis, including TFDP2, BAK and ABL. Expression of the genes was associated with the regulation of cell proliferation, apoptosis, differen-tiation, cell-cell interaction, invasion regulators and cytokines altered.

CONCLUSION: The results obtained from Atlas microarray provide a comprehensive liver cirrhosis specific expression profile. These results may be helpful for identification of target genes for diagnosis and designing rational therapeutic strategies.

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