Regulation of growth hormone (GH), insulin-like growth factor (IGF)I, IGF binding proteins -1, -2, -3 and GH binding protein during progression of liver cirrhosis

Low Growth Hormone Levels Predict Poor Outcome of Hepatitis B Virus-Related Acute-on-Chronic Liver Failure

Background and Aims: Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) remains a serious entity with high mortality. Growth hormone (GH) is related to the liver metabolism and regeneration. The present study aimed to explore the changes and prognostic efficacy of GH on the outcome of HBV-ACLF.

Methods: A prospective cohort of 124 patients and a cross-sectional cohort of 142 subjects were enrolled. GH and insulin-like growth factor-1(IGF-1) were detected by ELISA. Thirty-day survival was collected and the association between GH and the 30-day mortality of HBV-ACLF was analyzed.

Results: The mean age of the whole prospective cohort was 46.61 ± 12.71 years, and 19 (15.3%) patients were female. The median (IQR) of GH levels in non-survivors were 1106.55 (674.25, 1922.4) pg/ml, which were significantly lower than in survivors (p < 0.001). In the cross-sectional cohort, GH level was significantly higher in liver cirrhosis - acute decompensation (LC-AD) group than liver cirrhosis (LC) group (p < 0.001) while IGF-1 decreased significantly in LC, LC-AD, ACLF groups than health control (HC) and chronic Hepatitis B (CHB) groups (p < 0.001). The area under the receiver operating characteristic curve (AUROC) of GH for predicting 30-day mortality was 0.793. We built a new prognostic model, namely MELD-GH, which showed better predictive efficacy than Child-Pugh, MELD, CLIF-SOFA, and CLIF-C ACLF scores.

Conclusions: Low GH predicted the poor outcome of HBV-ACLF patients. GH and IGF-1 levels were differently distributed among HC, CHB, LC, LC-AD, and ACLF patients. MELD-GH had better predictive accuracy when compared to Child-Pugh, MELD, CLIF-SOFA, and CLIF-C ACLF scores.

Differential production of insulin-like growth factor-binding proteins in liver fibrosis progression

Noninvasive methods for liver disease diagnoses offer great advantages over biopsy, but they cannot be utilized in all cases. Therefore, specific indicators for chronic liver disease management are necessary. The aim was to assess the production of insulin-like growth factor-binding proteins (IGFBPs) 1-7 and their correlation with the different stages of fibrosis in chronic hepatitis C (CHC). A prospective, cross-sectional, multicenter study was conducted. CHC patients were categorized by FibroTest® and/or FibroScan®. Serum concentrations of IGFBPs 1-7 were determined through multiple suspension arrangement array technology. Significant differences were validated by the Kruskal-Wallis and Mann-Whitney U tests. Logistic regression models were performed to assess the association between the IGFBPs and fibrosis stages. The association was determined utilizing odds ratios (ORs), and receiver operating characteristic (ROC) curves were constructed to distinguish the IGFBPs in relation to the diagnosis of fibrosis. IGFBP-1 and IGFBP-7 concentrations were higher in CHC than in the healthy individuals, whereas IGFBP-3, IGFBP-5, and IGFBP-6 were downregulated in the patients. An apparent increase of all the IGFBPs was found at fibrosis stage F4, but with different regulations. IGFBP-2, -4, -6, and -7 had the best OR, showing the relation to fibrosis progression. The ROC curves showed that IGFBP-7 was the only protein that distinguished F1 from F3 and F2 from F3. IGFBPs participate in liver fibrosis progression and could be employed as circulating novel protein panels for diagnosis and as possible therapeutic targets in liver fibrosis progression.

Regenerative potential of platelets in patients with chronic kidney disease

INTRODUCTION

Chronic kidney disease (CKD) is a systemic disease affecting many organs. Progression of renal failure aggravates ongoing inflammation and increases oxidative stress. In the final stage of CKD, it is necessary to use renal replacement therapy. A side effect of dialysis therapy is the synthesis of proinflammatory factors and increased oxidative stress, which activates platelets and immune cells.

AIM OF THE STUDY

To determine the regenerative potential of platelets in patients with CKD based on the analysis of the relationships between substances with potential regenerative action, as well as analysis of the influence of the type of renal replacement therapy used on regeneration of platelets.

MATERIALS AND METHODS

The study group consisted of 117 patients. Based on the type of therapy used, patients were divided into four groups: hemodialysis, peritoneal dialysis, kidney transplant patients, and conservative treatment (30, 30, 27, and 30 patients). The control group consisted of 30 healthy volunteers. The concentrations of IGF-1, TGF-β, and PDGF-B in the blood serum were measured by ELISA methods.

RESULTS

It was shown that renal replacement therapy significantly influences the concentration of platelet growth factors (IGF-1: p = 0.025 and PDGF-B: p = 0.012). There was a relationship between the type of renal replacement therapy and the duration of dialysis, and the concentration of IGF-1, PDGF-B (p < 0.00001, p < 0.001).

CONCLUSIONS

The type of renal replacement therapy has a different effect on the concentration of platelet-derived growth factors IGF-1 and PDGF-B. PD patients had the highest concentrations of all growth factors, and this may be due to the presence of inflammation induced by dialysis-related advanced end-products of glycosylation (AGE).

IGFBP-1 and IGF-I as markers for advanced fibrosis in NAFLD - a pilot study

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease globally. Advanced fibrosis (stage 3-4) is the most robust marker for future mortality, but diagnosis requires liver biopsy. Current non-invasive scoring systems aimed to identify advanced fibrosis are imperfect. Insulin-like growth factor I (IGF-I) and its binding protein IGFBP-1 are liver derived proteins, that are involved in various liver disorders. The aim of this study was to examine the possible association between advanced fibrosis and IGF-I and IGFBP-1 in NAFLD.

METHODS

Fasting blood samples were obtained from 52 patients diagnosed with NAFLD by liver biopsy. Total IGF-I and IGFBP-1 concentrations were determined in serum by in-house radio-immuno-assays. IGF-I levels were age-standardized (IGF-SD). A logistic regression model was used to investigate the association of IGF-SD and IGFBP-1 with advanced fibrosis (stage 3-4).

RESULTS

Patients with advanced fibrosis (stage 3-4 vs. 0-2) had lower IGF-SD (-1.17 vs. 0.11, p = .01) and higher mean levels of IGFBP-1 (29.9 vs. 18.8 µg/l, p = .02). IGFBP-1 was associated with presence of advanced fibrosis (OR 1.04 per unit increase, 95%CI 1.0-1.07, p = .05), while IGF-1 was negatively associated with advanced fibrosis (OR 0.63 per standard deviation, 95%CI 0.44-0.92, p = .02).

CONCLUSIONS

This pilot study suggests an association between serum IGFBP-1 and IGF-I levels with advanced fibrosis in NAFLD patients. IGFBP1 and IGF-1 could be of interest as future biomarkers. Similar studies in larger cohorts are needed.

The insulin-like growth factor-1 and expression of its binding protein‑3 in chronic hepatitis C and hepatocellular carcinoma

The role of growth factors produced by the liver, including insulin-like growth factor-1 (IGF-1) and its main binding protein, IGF binding protein-3 (IGFBP-3), in hepatitis C virus (HCV)-associated carcinogenesis has only partially been recognized and there is not much data available on the local expression of IGF-1 and IGFBP-3 in chronic hepatitis C (CH‑C). Therefore, the aim of the present study was to evaluate the IGF‑1 and IGFBP‑3 serum levels and tissue expression in liver biopsies of CH‑C patients (n=37) and hepatocellular carcinoma (HCC) samples (n=61) as related to age- and gender-matched control serum samples (n=15) and healthy liver samples (n=10). Serum concentrations of IGF-1 (S-IGF-1) and IGFBP‑3 (S-IGFBP‑3) were measured by the ELISA method. Tissue expression of proteins was detected using ABC immunocytochemistry and evaluated applying a spatial visualization technique. Concentrations of S-IGF-1 and hepatic expression of IGF-1 (H-IGF-1) proved to be lower in CH-C compared to the controls. No significant differences were detected in the concentration of S-IGFBP-3 between the studied groups but the S-IGF-1/IGFBP-3 ratio in the CH-C group was significantly lower compared to the control. H-IGFBP-3 was higher in CH-C compared to those in the control and HCC. In HCC, lower expression of H-IGF-1 was detected compared to the control and a higher H-IGF-1/IGFBP-3 ratio compared to CH-C. A negative correlation was detected between S-IGF-1 and S-IGF-1/IGFBP-3 ratio, on the one hand, and age, grading and concentration of α-fetoprotein (AFP) on the other, while H-IGFBP-3 was negatively correlated with BMI in the CH‑C group. In patients with CH‑C, the H‑IGF‑1/IGFBP‑3 ratio was higher compared to that of the S‑IGF‑1/IGFBP‑3 ratio. The studies documented a disturbed H‑IGF‑1 and H‑IGFBP‑3 in CH‑C, which may be of significance in carcinogenesis. Examination of serum concentration and tissue expression of the two proteins and, first of all, estimation of the IGF‑1/IGFBP‑3 ratio may provide additional (to the estimation of IGF‑1 and AFP) non-invasive markers in HCV‑related liver injury.

The insulin-like growth factor (IGF) signaling axis and hepatitis C virus-associated carcinogenesis (review)

Insulin-like growth factor (IGF) signaling plays an important autocrine, paracrine and endocrine role in growth promotion involving various tissues and organs. Synthesis of both IGFs (IGF-1 and IGF-2) in normal conditions takes place mainly in the liver even if the proteins can be produced in every cell of the human body. The alterations in the IGF signaling axis in human hepatocarcinogenesis are described, but mechanisms of the interactions between expression of oncogenic hepatitis C virus (HCV) proteins and components of the IGF system in progression of chronic hepatitis C to primary hepatocellular carcinoma (HCC) have been poorly recognised. In advanced stages of liver diseases, lowered serum levels of IGF-1 and IGF-2 have been documented. This was supposed to reflect significant damage to liver parenchyma, a decreased number of growth hormone receptors and a decreased genomic expression of IGF binding proteins (IGF BPs). In HCC, a decreased tissue expression of IGF-1, and an increased expression of IGF-1 receptor (IGF-1R) were noted, compared to the control. Potential mechanisms of augmented IGF-2 expression in HCC were also described and dysregulation of IGF signaling in HCC was concluded to occur predominantly at the level of IGF-2 bioavailability. The review aimed at presentation of involvement of IGF-1, IGF-1R and IGF BPs (mostly IGF BP-3 and IGF BP-6) in HCV-related hepatocarcinogenesis. Manifestation of various mRNA transcripts and IGF-1 proteins and their potential involvement in carcinogenesis are also discussed.

Serum prolidase and IGF-1 as non-invasive markers of hepatic fibrosis during four different periods after bile-duct ligation in rats

AIM

Our aim was to study the correlation of serum prolidase and insulin like growth factor-1 to liver collagen and assess their utility as markers of fibrosis during four different periods of hepatic injury and fibrosis after bile-duct ligation in rats.

METHODS

Forty-eight Wistar albino rats were included in the study and divided into six groups. Seven rats served as the control group (Control), while seven rats had a sham operation (Sham group). Thirty-four rats underwent bile-duct ligation. Bile-duct ligated (BDL) animals were sacrificed at the end of the first week (Group 1; n = 8), second week (Group 2; n = 8), third week (Group 3; n = 9), or fourth week (Group 4; n = 9) after BDL. Liver collagen, liver prolidase, and serum prolidase and IGF-I, were determined.

RESULTS

There was a positive correlation between liver collagen and serum prolidase (r(s): 0.843, P < 0.001) levels and a negative correlation among liver collagen and serum IGF-1 levels (r(s): -0.667, P < 0.001). The peak levels of liver collagen and serum prolidase were reached in the third week while the lowest levels of IGF-1 were found at the end of the third week.

CONCLUSION

Serum prolidase and IGF-1 either independently or in combination correlate with liver collagen content in hepatic fibrosis.

Hepatitis-C patients have reduced growth hormone (GH) secretion which improves during long-term therapy with pegylated interferon-alpha

OBJECTIVES

In vitro and in vivo data indicate multiple, but contradictory effects of interferon on pituitary hormone secretion. We therefore investigated prospectively basal and stimulated pituitary hormone secretion in 21 patients with chronic hepatitis C virus (HCV) infection before and during antiviral therapy.

METHODS

Twenty-one patients received pegylated interferon-alpha plus either ribavirin or levovirin. Baseline and stimulated growth hormone (GH), cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), and thyroid-stimulating hormone (TSH) responses were measured using standard pituitary function tests, before therapy in all and during therapy in 17 out of the 21 patients.

RESULTS

Before therapy 17 patients (81%) had severe GH insufficiency and 9 of these had low insulin-like growth factor-1 (IGF-1) concentrations. Basal and stimulated GH concentrations increased significantly during therapy, reducing the number of patients with severe GH insufficiency to four, but IGF-1 remained low. Basal PRL and TSH concentrations were normal before and during therapy, while thyroid-releasing hormone (TRH)-stimulated concentrations increased significantly during therapy. The adrenocorticotropic hormone (ACTH)/cortisol axis, basal and stimulated gonadotropin, and testosterone concentrations were normal throughout. Neither the HCV RNA level nor transaminases correlated with hormone concentrations before or during therapy.

CONCLUSIONS

GH insufficiency is common in patients with chronic HCV infection. While GH secretion improves during antiviral therapy, IGF-1 remains low, indicating persistent GH resistance of hepatocytes. Whether improvement in GH secretion during treatment is due to a direct drug effect or related to the suppression of viral load could not be differentiated, as most patients demonstrated a positive virologic response.

Central laboratory reassessment of IGF-I, IGF-binding protein-3, and GH serum concentrations measured at local treatment centers in growth-impaired children: implications for the agreement between outpatient screening and the results of somatotropic axis functional testing

BACKGROUND

Childhood GH deficiency, suspected in the presence of decreased height velocity and short stature, is usually characterized by low IGF-I and IGF-binding protein-3 (IGFBP-3) serum concentrations and is conventionally confirmed by diminished GH peak responses to pharmacological stimuli.

OBJECTIVE

We evaluated the agreement between different IGF-I (IGFBP-3) assays in predicting GH deficiency and tested whether variability between growth factor screening and pharmacological testing could be diminished by reassessment of growth factor and GH peak concentrations in a single laboratory.

DESIGN

Using the Tuebingen IGF-I (IGFBP-3) RIA, 317 (321) sera from children evaluated for growth disorders in 19 centers were reanalyzed. In 103 children with insulin hypoglycemia and arginine tests, we evaluated how the association between the outcome of growth factor screening and functional testing would change if different assays were employed.

RESULTS

Locally measured IGF-I correlated better than IGFBP-3 with the results of the central laboratory (Tuebingen) assay (slope of the regression curve 1.05; 95% confidence interval (95% CI) 1.01-1.1 versus 1.18; 95% CI 1.09-1.3). Agreement between local and central laboratory assays in predicting GH deficiency was better for IGF-I than for IGFBP-3 assays (kappa =0.59 versus kappa =0.47). The poor agreement between growth factor screening and GH pharmacological testing was not improved when hormone concentrations were remeasured in the central laboratory (kappa local=-0.0031, central=0.12).

CONCLUSIONS

In children with impaired growth, growth factor screening reflects different aspects of GH insufficiency than does functional testing. Agreement between these approaches is poor and could not be improved by reduction of assay-related variability.

The insulin-like growth factor (IGF) system and its relation to infliximab treatment in adult patients with Crohn's disease

OBJECTIVE

Metabolic bone disease (MBD) and muscle wasting (MW) are serious complications in adult patients suffering from inflammatory bowel disease. These complications may be caused by alterations in the insulin-like growth factor (IGF) system. The aim of the present study was to assess changes in the IGF system in patients with active Crohn's disease (CD) before and during infliximab treatment.

MATERIAL AND METHODS

We studied 13 patients with therapy refractory CD, treated with infliximab (5 mg/kg body-weight) at baseline and after 2 weeks. The IGF system and markers of inflammation were examined at baseline, on days 2-5 and after 1, 4, and 8 weeks. Ten healthy age- and gender-matched persons served as controls.

RESULTS

Total IGF-I and IGF binding protein (IGFBP)-3 levels were reduced by 36% (p<0.05) and 27% (p<0.001), respectively, compared with those of controls, and normalized during the study period. Free IGF-I levels were reduced by 46% (p<0.05) compared with those of controls and remained suppressed. IGFBP-2 levels were increased at baseline by a factor 2.3 compared to controls (p<0.01) with partial normalization at the end of the study period. The Crohn's disease Activity Index, the Harvey Bradshaw Index, C-reactive protein, orosomucoid and albumin reached normal levels during infliximab treatment.

CONCLUSIONS

Treatment with infliximab normalized circulating levels of total IGF-I and IGFBP-3, and partially normalized IGFBP-2, whereas free IGF-I remained suppressed. We suggest that the changes in the IGF system may be part of the catabolic state in active CD and may have an association with MBD and MW.

The insulin-like growth factor (IGF)-system in active ulcerative colitis and Crohn's disease: relations to disease activity and corticosteroid treatment

BACKGROUND

Metabolic bone disease (MBD) and muscle wasting (MW) are serious complications in adults suffering from inflammatory bowel disease (IBD). The inflammatory process and corticosteroid treatment may lead to changes in the IGF-system associated with MBD and MW.

AIM

To assess changes in the IGF-system and clinical and biochemical markers in ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

We studied 37 IBD patients with severe clinical exacerbation (20 with UC, 17 with CD) before and during high dose corticosteroid treatment and tapering (8-12 weeks).

RESULTS

Total IGF-I was reduced in CD (36% p<0.01) and UC (41% p<0.001) before treatment and normalized completely. Free IGF-I baseline levels were unchanged compared to controls. In UC, free IGF-I levels increased significantly at week 1 and week 4 (p<0.01, respectively). In CD, no changes in free IGF-I levels were observed. IGFBP-2 baseline levels were increased by a factor 2.3 in UC and CD compared to controls (p<0.01 respectively) and normalized during treatment. IGFBP-3 was reduced by 38% (p<0.01) in CD and 32% (p<0.01) in UC with only partial normalization. Harvey-Bradshaw index, C - reactive protein and albumin normalized during treatment.

CONCLUSIONS

Significant changes in total and free IGF-I and IGFBP-2 and IGFBP-3 were demonstrated in CD and UC patients in exacerbation with only partial normalization during high dose corticosteroid treatment and tapering without differences between UC and CD. These changes may be part of MBD and MW in active IBD.

IGF-I measurements in the diagnosis of adult growth hormone deficiency

Although serum insulin-like growth factor I (IGF-I) concentrations have utility as a screening test for growth hormone (GH) deficiency in children and young adults, they are less accurate for screening in adults over 40 years of age. There are two main limitations in the clinical use of IGF-I levels as a marker of GH secretion. First, IGF-I synthesis is not only regulated by GH but also by nutrient supply and by other hormones; second, low IGF-I levels in the presence of normal or increased GH secretion may reflect a peripheral resistance to GH action. Although serum IGF-I cannot be used as a stand-alone test for the diagnosis of adult GH deficiency, very low IGF-I levels in the context of documented hypothalamic or pituitary disease may be helpful in identifying patients with a high probability of GH deficiency. In the presence of two or more additional pituitary hormone deficiencies, an IGF-I level <84 microg/l (assayed by Esoterix Endocrinology, Inc. Calabasas Hills, CA, USA) indicates a 99% probability of GH deficiency. As this cut-off value has not been validated for other IGF-I assays, an IGF-I standard deviation score (SDS) of <-3 may be considered in adults over age 28; an even lower IGF-I SDS is needed for diagnosis in younger adults. In clinical practice, other causes of low serum IGF-I such as malnutrition, diabetes, hypothyroidism, liver disease, etc., should be excluded before applying these diagnostic criteria.

Clinical utility of measurements of insulin-like growth factor 1

Plasma insulin-like growth factor 1 (IGF-I) concentrations are regulated by genetic factors, nutrient intake, growth hormone (GH) and other hormones such as T4, cortisol and sex steroids. The accuracy of IGF-I measurement in diagnosing GH deficiency or excess depends, in part, on the relative contributions of each of these variables. Since their respective influence may vary widely between individuals, the establishment of well-defined normal ranges is necessary, which requires adequate numbers of normal individuals, in order for IGF-I measurements to have maximum utility. In states of GH deficiency, the influence of these non-GH-related factors predominates. Although IGF-I levels have utility as a screening test in children and young adults, they cannot be used as a stand-alone test for the diagnosis of GH deficiency. By contrast, in acromegaly, GH is the predominant determinant of IGF-I levels and, therefore, measurement of IGF-I is a very useful diagnostic test. In acromegaly, IGF-I levels are useful for assessing the relative degree of GH excess, because changes in IGF-I correlate with changes in symptoms and soft-tissue growth. IGF-I is also very useful in monitoring the symptomatic response to therapy.

Physiology and pathophysiology of growth hormone-binding protein: methodological and clinical aspects

Circulating GH is partly bound to a high-affinity binding protein (GHBP), which in humans is derived from cleavage of the extracellular domain of the GH receptor. The precise biological function GHBP is unknown, although a regulation of GH bioactivity appears plausible. GHBP levels are determined by GH secretory status, body composition, age, and sex hormones, but the cause-effect relationships remain unclarified. In addition to the possible in vivo significance of GHBP, the interaction between GH and GHBP has methodological implications for both GH and GHBP assays. The present review concentrates on methodological aspects of GHBP measurements, GHBP levels in certain clinical conditions with a special emphasis on disturbances in the GH-IGF axis, and discusses the possible relationship between plasma GHBP and GH receptor status in peripheral tissues.

Expression of insulin-like growth factor-I and insulin-like growth factor binding proteins during thioacetamide-induced liver cirrhosis in rats

OBJECTIVE

The liver plays a central role in insulin-like growth factor (IGF) homeostasis providing the majority of circulating IGF-I and some of its binding proteins (IGFBPs). In liver cirrhosis the IGF axis is severely disturbed, and these alterations are associated with reduced IGF-I, IGFBP-3 but elevated IGFBP-1 serum levels.

METHODS

By Northern blotting and in situ hybridization (ISH), hepatic expression of IGF-I and of IGFBP was studied in a rat model of liver cirrhosis induced by thioacetamide.

RESULTS

ISH revealed a homogeneous distribution of IGFBP-1, IGFBP-4 and IGF-I mRNA over hepatic parenchyma in normal and cirrhotic liver. Fibrous septa of cirrhotic liver were IGFBP-1 mRNA negative, whereas IGFBP-4 and IGF-I transcripts were detected in single cells. In normal liver, IGFBP-3 mRNA was distributed within nonparenchymal cells of the hepatic lobule and in the wall of the portal vein. In cirrhotic liver, IGFBP-3 transcripts were abundant in mesenchymal cells of fibrous tissue. IGFBP-3 mRNA expression was also prominent in cells at the septal-nodular interface most likely representing monocyte infiltration. IGFBP-3 mRNA expression was reduced in nonparenchymal liver cells located more distantly from the septal-nodular interface in the cirrhotic nodule that correlated with reduced IGFBP-3 mRNA expression observed in Kupffer cells (KC) and sinusoidal endothelial cells (SEC) isolated from macronodular cirrhotic livers.

CONCLUSION

Cirrhosis is accompanied by an altered spatial expression of IGFBP-3 in liver tissue, which is characterized by decreased levels of IGFBP-3 mRNA in KC and SEC, but elevated IGFBP-3 expression in myofibroblast-like cells and inflammatory infiltrate.

Alterations in growth hormone receptor abundance regulate growth hormone signaling in murine obstructive cholestasis

Children with cholestatic liver diseases, in particular biliary atresia, may develop an acquired growth hormone (GH) resistance. This is characterized by normal GH secretion, reduced liver GH receptor (GHR) abundance, and reduced circulating insulin-like growth factor I (IGF-I). Consequences include linear growth failure, reduced muscle mass, and increased perioperative morbidity and mortality. However, the molecular basis for altered GH signaling in liver and skeletal muscle in cholestatic liver disease is not known. We hypothesized that reduced IGF-I expression in obstructive cholestasis would be associated with downregulation of the GHR and impaired phosphorylation of signal transducers and activators of transcription (STAT5). Body composition was determined in C57BL/6J male mice after bile duct ligation (BDL) relative to pair-fed (PF) and ad libitum-fed controls. GHR, STAT5, Sp3, and IGF-I expression and/or DNA binding were assessed using immunoblots, electrophoretic mobility shift assays, and/or real time RT-PCR. Fat-free mass was reduced in PF mice relative to ad libitum-fed controls. BDL led to a further reduction in fat mass and fat-free mass relative to PF controls. TNF-alpha was increased in liver and skeletal muscle of BDL mice. This was associated with reduced GH-dependent STAT5 activation and IGF-I RNA expression. GHR expression was reduced in BDL mice; in liver, this was associated with reduced Sp3 binding to a GHR gene promoter cis element. Wasting in murine obstructive cholestasis is due to combined effects of reduced caloric intake and biliary obstruction. GH resistance due to downregulation of GHR expression may be attributed primarily to the obstructive cholestasis; therapies that specifically increase GHR expression may restore GH signaling in this setting.

Insulin-like growth factors in patients with liver cysts

Insulin-like growth factors (IGFs) play an important role in cell growth and differentiation, and the liver is the main source of IGFs and IGF-binding proteins (IGFBPs) that appear in the circulation. The effect of liver cysts on the circulating IGF system was studied in this work. Serum concentrations of IGF-I and -II were measured by radioimmunoassay, IGFBP patterns were characterised by ligand-affinity and immunoblotting, and a lectin-binding assay was used to investigate the glyco component of IGFBP-3 complexes. IGF-I and -II concentrations in patients with cysts were significantly lower compared to those in healthy individuals (P<0.0001 and P<0.01, respectively), and the decrease was related to age but not sex. The overall mean concentrations of IGF-I and -II were not significantly different whether the cysts were caused by Echinococcus granulosus, cross-reactive pathologies, or some other factor. IGFBP profiles correlated with the amount of IGF present: patients with lower IGF-I concentrations expressed decreased IGFBP-3 and elevated IGFBP-2 levels. Increased IGFBP-3 proteolytic activity in the patients' blood was not detected by immunoblotting. In the lectin-binding assay, IGFBP-3 complexes in the circulation of patients demonstrated reactivity similar to that in healthy persons, suggesting that the overall structure of the saccharide moieties of the IGFBP-3 complexes was not significantly altered due to liver cyst formation.

Elevated insulin, proinsulin and insulin-like growth factor-binding protein-1 in liver disease

Insulin-like growth factor-binding protein-1 (IGFBP-1) is one of six soluble binding proteins that regulate the actions of the insulin-like growth factors (IGFs). Liver is the major source of IGFBP-1 in non-pregnant humans. In normal physiology, IGFBP-1 transcription is potently inhibited by insulin and serum levels are limited by a rapid clearance rate. Elevated levels of IGFBP-1 in liver disease have been attributed to insulin resistance; however, the relationships between these analytes have not been defined. We studied insulin, proinsulin and IGFBP-1 in normal subjects (NL, N=47, 43+/-12 yr), cirrhosis (CIR, N=29, 54+/-14 yr), hepatocellular carcinoma (HCC, N=42, 61+/-11 yr), and other liver tumors (TUM, N=8, 60+/-17 yr). All three analytes were significantly increased in liver disease (mean+/-SEM; p-values relative to normals): IGFBP-1 (NL 24+/-4 ng/ml; CIR 235+/-53, p<0.0001; HCC 505+/-105, p<0.0001; TUM 118+/-36, p<0.0001), insulin (NL 72+/-4 pM; CIR 261+/-62, p<0.0002; HCC 180+/-25, p<0.0001; TUM 189+/-58, p<0.0001), proinsulin (NL 6.5+/-0.7 pM; CIR 36.8+/-7.7, p<0.0001; HCC 26.2+/-3.8, p<0.0001; TUM 32.1+/-9.7, p<0.0001). The ratio of proinsulin to insulin was also significantly elevated in liver disease. A typical curvilinear inverse relationship of insulin and IGFBP-1 was observed, but was shifted several fold higher for the liver disease groups. Our results demonstrate that insulin and proinsulin are elevated in liver disease. However, these elevations are paradoxically accompanied by elevated IGFBP-1 levels, indicating disruption of normal regulatory mechanisms. IGFBP-1 is postulated to play a dynamic role in metabolic substrate utilization via regulation of free IGF. Therefore, inappropriate elevation of IGFBP-1 could play an important role in the metabolic disturbances associated with liver disease.

Insulin-like growth factors and their binding proteins in the circulation of patients with echinococcosis, trichinellosis and toxoplasmosis

BACKGROUND

Insulin-like growth factors (IGFs) are polypeptide hormones that play anabolic roles in cellular growth and metabolism. Their activity is regulated by binding proteins (IGFBPs) and degradation mechanisms. The liver is regarded as the main source of circulating forms and the levels change in various disease states. The aim of the study was to explore the effects of parasitic infections on the circulating IGFs and IGFBPs.

METHODS

Peptide concentrations in sera of patients with echinococcosis, trichinellosis and toxoplasmosis were measured by radioimmunoassay, while IGFBP patterns were characterised by ligand-affinity blotting and gel chromatography.

RESULTS

IGF-I levels were reduced in trichinellosis (p=0.016), with the increased relative amounts of IGFBP-1, -2 and -4. The significantly reduced levels of IGF-I (p<0.001), IGF-II (p=0.017) and IGFBP-3 and the increased presence of IGFBP-2 were found in patients with echinococcosis.

CONCLUSIONS

In subjects with trichinellosis probably the combined effects of inadequate nutrition and the immunological response occurred. A possible explanation for the changes found in patients with echinococcosis is that the liver is a frequent target organ for Echinococcus granulosus. Since liver cysts were present in these patients, it can be expected that hepatic injury may affect liver metabolism leading to altered IGF/IGFBP profiles.

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

AIM

To study the expression of IGF-1 and IGF-1R and its intervention by interleukin-10 in the course of experimental hepatic fibrosis.

METHODS

Hepatic fibrosis was induced in rats by carbon tetrachloride intoxication and liver specimens were taken from the rats administered CCl4 with or without IL-10 treatment and the animals of the control group. Immunoreactivities for insulin-like growth factor-1 (IGF-1) and IGF-1 receptor(IGF-1R) were demonstrated by immunohistochemistry, and their intensities were evaluated in different animal groups.

RESULTS

The positive levels for IGF-1 and IGF-1R were increased with the development of hepatic fibrosis, with the positive signals localized in cytoplasm and/or at the plasmic membrane of hepatocytes. The positive signals of IGF-1 and IGF-1R were observed more frequently (P<0.01) in the CCl4-treated group (92.0 % and 90.0 %) compared to those in the control group. The positive signals decreased significantly (P<0.05) in IL-10-treated group. The responses in IGF-1 and IGF-1R expression correlated with the time of IL-10 treatment.

CONCLUSION

The expression of IGF-1 and IGF-1R immunoreactivities in liver tissue seems to be up-regulated during development of hepatic fibrosis induced by CCl(4), and exogenic IL-10 inhibits the responses.

Dysfunction of the hypothalamic-pituitary-glandular axes and relation to Child-Pugh classification in male patients with alcoholic and virus-related cirrhosis

OBJECTIVE

To investigate anterior pituitary function (adrenal, somatotropic, thyroid and gonadal axes, and prolactin) in relation to the Child-Pugh score in male patients with alcoholic and virus-related liver cirrhosis.

METHOD

Anterior pituitary function was evaluated in 52 male cirrhotics (26 Child-Pugh class A (CPA), 16 Child-Pugh class B (CPB) and 10 Child-Pugh class C (CPC)) by a combined pituitary stimulation test, and was compared with 50 age-matched controls.

RESULTS

A normal cortisol response to corticotropin-releasing hormone (CRH) stimulation was demonstrated in 57.6% of CPA patients, 31.1% of CPB patients and 20% of CPC patients, while basal levels of adrenocorticotropic hormone (ACTH) and cortisol in cirrhotics were comparable to those in controls. Levels of basal growth hormone (P < 0.001) and stimulated growth hormone (P < 0.01) were significantly higher in cirrhotics compared with controls, while levels of insulin-like growth factor 1 (IGF-1) were significantly lower (P < 0.001). Basal prolactin levels were elevated significantly in CPC patients (P < 0.01), while stimulated prolactin as well as basal and stimulated thyroid-stimulating hormone (TSH) levels were comparable. Basal luteinizing hormone levels were significantly higher in CPA (P < 0.001) and CPB (P < 0.001) patients, and stimulated luteinizing hormone levels were significantly lower in CPC patients than in controls (P < 0.005). Basal and stimulated follicle-stimulating hormone (FSH) levels were comparable in all groups. Child-Pugh score was correlated positively to prolactin and was correlated negatively to IGF-1, stimulated luteinizing hormone and free testosterone.

CONCLUSIONS

In cirrhotics, the hypothalamic-pituitary-adrenal and -gonadal axes and prolactin secretion are impaired. Growth hormone response to growth hormone-releasing hormone (GHRH) is accelerated in cirrhotics. Thus, elevated basal and stimulated levels of growth hormone probably reflect compensation for low levels of IGF-1, which are associated with deteriorating liver function. The aetiology of cirrhosis was found to have no influence on the degree of alteration of the hypothalamic-pituitary-glandular axes.

Dysfunction of the hypothalamic-pituitary-glandular axes and relation to Child-Pugh classification in male patients with alcoholic and virus-related cirrhosis

OBJECTIVE

To investigate anterior pituitary function (adrenal, somatotropic, thyroid and gonadal axes, and prolactin) in relation to the Child-Pugh score in male patients with alcoholic and virus-related liver cirrhosis.

METHOD

Anterior pituitary function was evaluated in 52 male cirrhotics (26 Child-Pugh class A (CPA), 16 Child-Pugh class B (CPB) and 10 Child-Pugh class C (CPC)) by a combined pituitary stimulation test, and was compared with 50 age-matched controls.

RESULTS

A normal cortisol response to corticotropin-releasing hormone (CRH) stimulation was demonstrated in 57.6% of CPA patients, 31.1% of CPB patients and 20% of CPC patients, while basal levels of adrenocorticotropic hormone (ACTH) and cortisol in cirrhotics were comparable to those in controls. Levels of basal growth hormone (P < 0.001) and stimulated growth hormone (P < 0.01) were significantly higher in cirrhotics compared with controls, while levels of insulin-like growth factor 1 (IGF-1) were significantly lower (P < 0.001). Basal prolactin levels were elevated significantly in CPC patients (P < 0.01), while stimulated prolactin as well as basal and stimulated thyroid-stimulating hormone (TSH) levels were comparable. Basal luteinizing hormone levels were significantly higher in CPA (P < 0.001) and CPB (P < 0.001) patients, and stimulated luteinizing hormone levels were significantly lower in CPC patients than in controls (P < 0.005). Basal and stimulated follicle-stimulating hormone (FSH) levels were comparable in all groups. Child-Pugh score was correlated positively to prolactin and was correlated negatively to IGF-1, stimulated luteinizing hormone and free testosterone.

CONCLUSIONS

In cirrhotics, the hypothalamic-pituitary-adrenal and -gonadal axes and prolactin secretion are impaired. Growth hormone response to growth hormone-releasing hormone (GHRH) is accelerated in cirrhotics. Thus, elevated basal and stimulated levels of growth hormone probably reflect compensation for low levels of IGF-1, which are associated with deteriorating liver function. The aetiology of cirrhosis was found to have no influence on the degree of alteration of the hypothalamic-pituitary-glandular axes.

Hepatocellular kinetics and the expression of growth hormone (GH) in the livers and liver tumours of GH-transgenic mice

Although it is well known that transgenic mice that overexpress growth hormone (GH) frequently develop liver tumours, the precise nature of the relationship between the overexpression of GH and hepatocarcinogenesis is not clear. The current study was designed to investigate the relationship between the expression of the GH transgene and changes in hepatocyte morphology and kinetics, prior to and during hepatocarcinogenesis in GH-transgenic mice. In young mice (1-month-old) prior to tumour development, GH protein, as detected by immunohistochemistry, was observed in the cytoplasm of essentially all hepatocytes. In liver tissues of older animals, apoptotic cells and hypertrophic hepatocytes did not express immunoreactive GH, even though GH was expressed strongly in the smaller hepatocytes. A relatively high proportion of large dysplastic hepatocytes (>50 microm) were apoptotic (TUNEL positive), whereas smaller hepatocytes featured more prominently in the proliferative phase, as measured by BrdU incorporation. GH expression in tumour tissue, as detected by immunohistochemistry, was often variable and generally decreased with tumour development. Northern blot analysis showed that equivalent levels of GH mRNA were present in tumour tissue and adjacent liver. However, there was no clear trend when the levels of GH mRNA extracted from adenoma, and hepatocellular carcinoma, were compared. These observations help clarify some of the mechanisms by which GH promotes hepatocarcinogenesis in GH-transgenic mice.

The insulin-like growth factor binding protein 3 ternary complex is reduced in cirrhosis

BACKGROUND/AIMS

In healthy adults, serum insulin-like growth factor I (IGF-I), IGF binding protein 3 (IGFBP-3) and acid labile subunit (ALS) form a 150-kDa ternary complex under the control of growth hormone (GH). Approximately 80-90% of circulating IGF-I is bound to the ternary complex. In cirrhosis the GH/IGF axis is severely disturbed and the individual components of the ternary complex are reduced. However, the degree of ternary complex formation in cirrhosis has not previously been described.

METHODS

Serum IGF-I, IGFBP-3, ALS, the 150-kDa ternary complex and IGFBP-3 proteolysis were all measured in six compensated and six decompensated cirrhotic patients and compared to six healthy controls.

RESULTS

Patients with compensated cirrhosis had decreased levels of IGF-I (55%), IGFBP-3 (64%) and ALS (53%), and in the decompensated patients these levels were decreased even further: IGF-I (32%), IGFBP-3 (37%) and ALS (27%) compared to healthy controls. The levels of the ternary complex followed this pattern, with low levels seen in the compensated patients (66%) and a further reduction in the decompensated patients (27%). Ternary complex levels correlated negatively with the Child-Pugh score. No increase in IGFBP-3 proteolysis was found in cirrhotic patients compared to healthy controls.

CONCLUSION

Cirrhosis is associated with reduced levels of the 150-kDa ternary IGFBP-3 complex correlating with the degree of liver disease.

Overexpressed growth hormone (GH) synergistically promotes carcinogen-initiated liver tumour growth by promoting cellular proliferation in emerging hepatocellular neoplasms in female and male GH-transgenic mice

BACKGROUND/AIMS

Growth hormone (GH), when overexpressed in male and female GH-transgenic mice, is known to induce liver tumours within 1 year. This study aimed to gain a clearer understanding of the interaction between GH and tumour cells in vivo.

METHODS/RESULTS

The carcinogen diethylnitrosomine (DEN) was administered to neo-natal transgenic and non-transgenic mice maintained in a "hepatocarcinogenesis resistant" genetic background (C57BL/6J). Macroscopic, microscopic and liver weight/body weight ratio analyses revealed that carcinogen-induced hepatocarcinogenesis was dramatically accelerated in young GH-transgenic mice compared to non-transgenic counterparts. Image analysis of microscopic hepatocellular neoplasms showed rapidly increasing tumour burdens, and neoplastic foci size over time in young adult GH-transgenic mice. The magnitude of enhanced tumour growth was equivalent in both male and female transgenic mice, whereas much lower and sexually dimorphic tumour growth rates (males>females) were observed in non-transgenic mice treated with DEN. BrdU labelling experiments demonstrated that rapid tumour growth in carcinogen-treated GH-transgenic mice was due to the promotion of cell proliferation in emerging lesions. Tumour cell proliferation in young GH-transgenic mice was 2.6- and 4-fold higher, respectively, than that observed in similar age male and female non-transgenic mice. Interestingly, both GH-transgenic and non-transgenic mice displayed progressively slower tumour growth rates in older animals.

CONCLUSION

Overall, GH synergistically promotes carcinogen-induced hepatocarcinogenesis in both sexes of GH-transgenic mice by stimulating tumour cell proliferation.

Circulating levels of insulin-like growth factors and their binding proteins in patients with chronic liver disease: lack of correlation with bone mineral density

BACKGROUND/AIMS

Insulin-like growth factor-I (IGF-I) levels are low in patients with chronic liver disease (CLD) and have been found to correlate with measurements of bone mineral density (BMD) in men with viral cirrhosis. The aim of this study was to investigate the relationship between circulating IGF-I levels and BMD in patients with CLD of other causes.

METHODS

Fifty-eight patients with CLD were included. Age- and sex-matched normal individuals served as controls. Serum levels of IGF-I and IGF-II and their binding proteins (IGFBP-1-3) were measured by radioimmunoassay. BMD was measured by dual energy X-ray absorptiometry.

RESULTS

IGF-I levels were 57+/-33 and 136+/-48 ng/ml; p<0.0001 in patients and controls, respectively. IGF-II and IGFBP-3 levels were lower (p<0.0001) and IGFBP-1 and IGFBP-2 levels were higher in patients compared with controls (p<0.0005 and p<0.0001, respectively). All growth factors, except for IGFBP-2, correlated with parameters of liver function. In a multiple regression analysis, adjusting for age, no correlation was found between IGF-I, IGF-II, IGFBP-1-3 and BMD in either patients or controls.

CONCLUSION

Patients with CLD have low levels of IGF-I, IGF-II and IGFBP-3 that correlate with liver function. No relationship was found between low levels of growth factors and BMD.

Growth hormone binding protein 2001

The present state of knowledge about growth hormone binding proteins (GHBP) is reviewed, with particular emphasis on the high affinity GHBP, which represents the circulating ectodomain of the growth hormone receptor (GHR). GHBP is conserved through vertebrate evolution, is produced in many tissues (especially liver) by either alternative GHR mRNA splicing (rodents) or by proteolytic cleavage from the GHR (humans, rabbits and several other species). The metalloprotease TACE (tumor necrosis factor-alpha converting enzyme) is the likely enzyme responsible for cleavage, but the structural requirements for TACE recognition or catalysis, and hence the precise cleavage point in the GHR, are unknown. GHBP is widely distributed in biological fluids, with marked concentration differences amongst them. GHBP binds about half of the circulating GH under basal conditions but is easily saturated at high GH levels; it subserves complex functions, including a circulating buffer/reservoir function for GH, prolongation of plasma GH half-life, competition with GHRs for GH, and probably unproductive heterodimer formation with the GHR. The net effect of these partly enhancing and partly inhibitory functions on GH action in vivo is complex and difficult to ascertain. Serum GHBP levels roughly parallel GHR expression (particularly in liver) through the life span, with very low levels in fetal life, upregulation to adult levels during childhood, and decline in senescence. Rodent pregnancy is associated with a massive increase in GHBP expression. Although the regulation of GHBP expression/production is not necessarily tightly linked to GHR expression, in general, low GHBP levels occur in conditions associated with GH resistance (e.g., malnutrition, uncontrolled diabetes, catabolic states, renal failure, hypothyroidism). Conversely, obesity, a condition with enhanced GH responsivity, is associated with elevated GHBP levels. This suggests that in many (but not all) instances of abnormal GH action, the GHBP level reflects GHR status. Laron syndrome (genetic GHR deficiency/dysfunction due to mutations in the GHR gene) is associated with low or undetectable GHBP in 75-80% of patients; GHBP measurement can therefore be used diagnostically. Depending on the design of assays for serum GH, endogenous GHBP may interfere to varying degrees, and GH assays should be individually validated and optimized in this regard. The ultimate biological role and physiological significance of the GHBP remain to be established.

Alterations of IGF-binding proteins in patients with alcoholic liver cirrhosis

The protein synthetic activity of the liver is diminished in cirrhosis. The aim of this study was to investigate possible changes in the serum IGF-IGFBP system among patients with alcoholic liver cirrhosis (ALC). The results obtained demonstrated that serum IGF-I and IGF-II concentrations were significantly lower in patients with ALC than in healthy persons (P=0.0008 for IGF-I and 0.0002 for IGF-II). The IGFBP profile was markedly altered and the 34 kDa IGFBP from patients had higher affinity towards 125I-IGF-II compared to the 34 kDa IGFBP of control individuals. Moreover, the 40-45 kDa IGFBP (in isolated complex with 125I-IGF-II) exhibited diminished interaction with concanavalin A, wheat germ, and breadfruit lectins. Modification of the glyco-component of the 40-45 kDa IGFBP seems to be an early event in ALC since change in reactivity towards lectins was noticed in patients with ALC classified as Child score A, whose serum IGF-I and IGF-II levels were within reference limits (the existence of carbohydrate microheterogeneity of this IGFBP was also assessed by lectin-affinity electrophoresis). It is possible that these biochemical alterations may affect the functional activity of the IGFs by changing the dynamics and distribution of these growth factors in the organism.

The severity of chronic heart failure due to coronary artery disease predicts the endocrine effects of short-term growth hormone administration

Treatment with human recombinant GH has yielded conflicting results in patients with heart failure. As GH sensitivity may be important for treatment effects, the present study evaluated GH secretion and sensitivity in noncachectic patients with ischemic heart failure. Twenty clinically stable, male patients with moderate heart failure (mean New York Heart Association class, 2.0 +/- 0.8; mean ejection fraction, 30.0 +/- 8.4%) due to coronary artery disease were randomly assigned single blind to a low dose (group A; n = 10) and a high dose (group B; n = 10) group, receiving either 5 microg/kg x day recombinant human GH for 4 days followed by 10 microg/kg x day GH for another 4 days or 10 and 20 microg/kg x day GH, respectively. Cardiac function was assessed by echocardiography. Serum insulin-like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3), and 24-h urinary GH excretion as a measure of pituitary GH secretion were determined at baseline and on days 5 and 9. Baseline IGF-I and IGFBP-3 levels and GH excretion were significantly diminished compared to those in age-matched controls. There was a dose-dependent increase in IGF-I and IGFBP-3 during GH treatment. The increase in IGF-I induced by 10 microg/kg x day GH correlated positively to left ventricular ejection fraction (r = 0.59; P = 0.006) and inversely to left ventricular end-diastolic and end-systolic dimensions (r < -0.6 and P < 0.01 for both). In conclusion, GH secretion and serum levels of IGF-I and IGFBP-3 are diminished in patients with moderate ischemic heart failure. Left ventricular function determines the sensitivity of the GH/IGF-I system, measured as the IGF-I response to GH application. This finding suggests that individual dose adjustments may be an indispensable prerequisite for successful GH therapy in heart failure.

Serum insulin-like growth factor (IGF)-II is more closely associated with liver dysfunction than is IGF-I in patients with cirrhosis

The aim of this investigation was to determine the total concentrations of the insulin-like growth factors (IGF-I and IGF-II) in the blood serum of patients with liver cirrhosis and to evaluate their association with the condition. Cirrhosis was alcohol induced (n=27), of viral origin (n=17) or due to combined or other causes (n=21) and was moderate or severe in similar numbers of cases (Child A: n=21; Child B: n=21; Child C: n=23). While serum levels of both peptides were lower in patients than in age-matched healthy subjects (n=81), there was considerable overlap into the lower normal range for IGF-I. Moreover, no correlation between disease severity (Child score) and serum IGF-I was observed. Since a total of 78% of the results for IGF-II were outside the normal range (95% confidence interval) and serum concentrations were correlated with Child score (P=0.007), it is suggested that serum IGF-II concentrations may reflect compromised hepatic function more closely than IGF-I.

Growth hormone/insulin-like growth factor 1 axis alterations contribute to disturbed protein metabolism in cirrhosis patients after hepatectomy

BACKGROUND/AIM

Liver cirrhosis is accompanied by a fall in whole-body protein turnover and alterations of the growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis. However, the influence of liver cirrhosis on the GH/IGF-1 axis in the perioperative period, and the contribution of the GH/IGF-1 axis alteration in cirrhosis to postoperative nitrogen metabolism are not known.

METHODS

Plasma GH, IGF-1 and IGF binding protein 3 (IGF-BP3) levels were measured sequentially in patients undergoing hepatectomy with or without cirrhosis. Postoperative nitrogen excretion and whole-body protein turnover rate were also determined.

RESULTS

Preoperative plasma IGF-1 level showed a negative correlation with indocyanine green retention rate. Cirrhosis patients undergoing hepatectomy had low IGF-1 and IGF-BP3 levels, despite extremely high GH levels in the perioperative period. Perioperative IGF-1 levels were lower in patients with postoperative complications than in those without complications. Postoperative nitrogen excretion was higher and whole-body protein turnover rate was lower in patients with cirrhosis than in those without cirrhosis. The post-operative IGF-1 level showed a positive correlation with whole-body protein turnover rate.

CONCLUSIONS

Postoperative hepatic IGF-1 production may be severely disturbed in patients with cirrhosis, and the impaired IGF-1 production contributes to the suppressed postoperative protein metabolism in cirrhosis. It may be appropriate to increase plasma IGF-1 level in patients with cirrhosis to enhance postoperative protein metabolism and improve the postoperative outcome.

Spontaneous pulsatility and pharmacokinetics of growth hormone in liver cirrhotic patients

BACKGROUND/AIMS

Liver cirrhosis is characterized by high serum growth hormone levels and low serum insulin-like growth factor I and growth hormone-binding protein levels. The present study was designed to characterize the serum profile of growth hormone and growth hormone pharmacokinetics in postnecrotic liver cirrhosis, correlating it with liver function and nutritional states.

METHODS

Fifteen patients were grouped by the Child-Pugh score (group 1, score of 5 to 8; group 2, score of 9 to 12). Five healthy subjects served as controls. Nutritional status was assessed by the creatinine-height index. Baseline growth hormone, insulin-like growth factor, and growth hormone binding protein were measured, and growth hormone pharmacokinetics was followed for 48 h after administration of subcutaneous recombinant human growth hormone (0.06 mg/kg).

RESULTS

Trough serum growth hormone (microg/l) was higher in both patient groups (5.3+/-3.6) than in controls (1.0+/-0.3; p<0.01). More pulses were recorded in cirrhotic patients, and mean pulse amplitude (microg/l) was higher in cirrhotic patients than in controls (p<0.01). After subcutaneous recombinant human growth hormone injection, maximal growth hormone was higher in cirrhotic patients and the area under the curve over 24 h was greater (626+/-120) than in controls (330+/-54; p<0.01). Single regression analysis showed a weak correlation of both the Child-Pugh score and the creatinine-height index with the pharmacokinetic parameters.

CONCLUSIONS

Due to decreased growth hormone clearance, patients with liver cirrhosis have increased trough and peak serum growth hormone levels, as well as lower serum growth hormone binding protein and insulin-like growth factor. Recombinant human growth hormone pharmacokinetics are typical of a high hepatic extraction substance administered to patients with liver disease and portal hypertension, and this may be relevant to the further use of growth hormone therapy.

Biliary cirrhosis induces type IIx/b fiber atrophy in rat diaphragm and skeletal muscle, and decreases IGF-I mRNA in the liver but not in muscle

BACKGROUND/AIMS

Patients with cirrhosis complain of fatigue, which in part may be due to the progressive muscle atrophy, noted especially when signs of decompensation appear. In addition, weaning from mechanical ventilation may be difficult in some patients following liver transplantation. Since little is known about the peripheral muscles and the diaphragm in cirrhosis, we investigated diaphragm and gastrocnemius histochemical properties, and diaphragm contractile properties in male rats with biliary cirrhosis. In addition, the extent to which insulin-like growth factor I (IGF-I) was involved in the regulation of muscle function was also examined, since IGF-I is known to induce growth and regeneration as well as to exert a protein anabolic action.

METHODS

Ten rats underwent a sham operation, while another ten underwent bile duct ligation and excision. After 5 weeks, biliary cirrhosis was confirmed histologically in random liver biopsies.

RESULTS

Compared to sham animals, diaphragm mass in cirrhotic rats was decreased by 10% (p<0.05), while masses of other respiratory (e.g. scalenus medius -21%, p<0.001) or peripheral muscles (e.g. gastrocnemius -24%, p<0.0001) decreased more. No changes in diaphragm force nor in its endurance were observed between the two groups. However, a clear decrease in the cross-sectional area of type IIx/b muscle fiber was present in both diaphragm (1360+/-147 vs 1112+/-167 microm2, p<0.02) and gastrocnemius (1954+/-265 vs 2328+/-245 microm2, p<0.02). Finally, hybridization of Northern blot with a rat cDNA IGF-I probe (gift from Dr D. Leroith, Bethesda, USA) labeled with alpha-32P revealed that in cirrhotic rats, the relative expression of IGF-I was markedly reduced by 45% in the liver (p<0.05) but was unchanged in the two muscles studied.

CONCLUSIONS

In this model of biliary cirrhosis: (i) muscle wasting was less pronounced in the diaphragm than in other muscles; (ii) type IIx/b fiber atrophy in respiratory (diaphragm) and peripheral muscles (gastrocnemius) developed while diaphragm contractile properties remained unchanged; and (iii) the relative expression of IGF-I was reduced in the liver only, while it remained unchanged in the muscle. The functional significance of these changes, their pathogenesis and presence in other models and in human cirrhosis remain to be elucidated.

Hepatoma with severe non-islet cell tumor hypoglycemia

We report a 22-yr-old male patient with chronic hepatitis B and a large, well differentiated hepatoma who developed episodes of symptomatic fasting hypoglycemia, which were caused by paraneoplastic secretion of unprocessed "big" insulin-like growth factor-II. Initially, the patient presented with normal liver function, which deteriorated during the clinical course. Therapeutic attempts to reduce tumor mass failed and the patient subsequently died because of metastases of the hepatoma. The pathophysiology of non-islet cell tumor hypoglycemia, differential diagnosis, and therapeutic options are discussed.

Molecular regulation of insulin-like growth factor-I and its principal binding protein, IGFBP-3

The insulin-like growth factors (IGFs) have diverse anabolic cellular functions, and structure similar to that of proinsulin. The distribution of IGFs and their receptors in a wide variety of organs and tissues enables the IGFs to exert endocrine, paracrine, and autocrine effects on cell proliferation and differentiation, caloric storage, and skeletal elongation. IGF-I exhibits particular metabolic responsiveness, and circulating IGF-I originates predominantly in the liver. Hepatic IGF-I production is controlled at the level of gene transcription, and transcripts are initiated largely in exon 1. Hepatic IGF-I gene transcription is reduced in conditions of protein malnutrition and diabetes mellitus, and our laboratory has used in vitro transcription to study mechanisms related to diabetes. We find that the presence of sequences downstream from the major transcription initiation sites in exon 1 is necessary for the diabetes-induced decrease in IGF-I transcription. Six nuclear factor binding sites have been identified within the exon 1 downstream region, and footprint sites III and V appear to be necessary for metabolic regulation; region V probes exhibit a decrease in nuclear factor binding with hepatic nuclear extracts from diabetic animals. IGFs in biological fluids are associated with IGF binding proteins, and IGFs circulate as a 150-kDa complex that consists of an IGF, an IGFBP-3, and an acid-labile subunit. Circulating IGFBP-3 originates mainly in hepatic nonparenchymal cells, where IGF-I increases IGFBP-3 mRNA stability, but insulin increases IGFBP-3 gene transcription. Regulation of IGFBP-3 gene transcription by insulin appears to be mediated by an insulin-responsive element, which recognizes insulin-responsive nuclear factors in both gel mobility shift assays and southwestern blots. Studies of mechanisms underlying the modulation of IGF-I and IGFBP-3 gene transcription, and identification of critical nuclear proteins involved, should lead to new understanding of the role and regulation of these important growth factors in diabetes mellitus and other metabolic disorders.