Insulin-like growth factor-1 deficiency and metabolic syndrome

Consistent evidence associates IGF-1 deficiency and metabolic syndrome. In this review, we will focus on the metabolic effects of IGF-1, the concept of metabolic syndrome and its clinical manifestations (impaired lipid profile, insulin resistance, increased glucose levels, obesity, and cardiovascular disease), discussing whether IGF-1 replacement therapy could be a beneficial strategy for these patients. The search plan was made in Medline for Pubmed with the following mesh terms: IGF-1 and "metabolism, carbohydrate, lipids, proteins, amino acids, metabolic syndrome, cardiovascular disease, diabetes" between the years 1963-2015. The search includes animal and human protocols. In this review we discuss the relevant actions of IGF-1 on metabolism and the implication of IGF-1 deficiency in the establishment of metabolic syndrome. Multiple studies (in vitro and in vivo) demonstrate the association between IGF-1 deficit and deregulated lipid metabolism, cardiovascular disease, diabetes, and an altered metabolic profile of diabetic patients. Based on the available data we propose IGF-1 as a key hormone in the pathophysiology of metabolic syndrome; due to its implications in the metabolism of carbohydrates and lipids. Previous data demonstrates how IGF-1 can be an effective option in the treatment of this worldwide increasing condition. It has to distinguished that the replacement therapy should be only undertaken to restore the physiological levels, never to exceed physiological ranges.

Hepatoprotective effects of insulin-like growth factor I in rats with carbon tetrachloride-induced cirrhosis

BACKGROUND & AIMS

Bioavailability of insulin-like growth factor (IGF-I) is reduced in liver cirrhosis. The aim of this study was to analyze the effect of IGF-I on liver histopathology and function in experimental cirrhosis.

METHODS

Rats received CCl4 inhalations for 11 or 30 weeks (protocols 1 and 2, respectively) and were treated with 2 microg x 100 g body wt(-1) x day(-1) IGF-I (group CI + IGF) or saline (group CI) on weeks 13 and 14 (protocol 1) or on weeks 28-30 (protocol 2). Normal rats were studied in parallel.

RESULTS

Serum albumin and total protein levels were reduced in CI but not in CI + IGF rats compared with normal rats. Clotting factors II, VII, and X were significantly greater in CI + IGF than in CI rats. Liver lipid peroxidation products were significantly increased in CI but not in CI + IGF rats, and liver fibrosis was less pronounced in CI + IGF than in CI animals. The activities of antioxidant enzymes and mitochondrial transmembrane potential were reduced compared with normal animals in CI but not in CI + IGF rats.

CONCLUSIONS

IGF-I improves liver function and reduces oxidative liver damage and fibrosis in rats with compensated or advanced liver cirrhosis. Improved mitochondrial function could play a role in the hepatoprotective effect of this hormone.

Insulin-like growth factor I (IGF-I) replacement therapy increases albumin concentration in liver cirrhosis: results of a pilot randomized controlled clinical trial

BACKGROUND/AIMS

Insulin-like growth factor I (IGF-I) is an anabolic hormone synthesized in the liver whose levels decrease sharply in liver cirrhosis.

METHODS

We conducted a randomized double-blind placebo-controlled clinical trial to evaluate the effect of subcutaneous administration of IGF-I (20 microg/kg/day with dose escalation to 50-100 microg/kg/day) for 4 months in patients with alcoholic or primary biliary cirrhosis (PBC) and subnormal IGF-I levels. Eight alcoholics and one PBC entered the placebo group and seven alcoholics and two PBC the treatment group. Biochemistry, body composition, muscle mass and strength, and resting energy expenditure (REE) were evaluated.

RESULTS

Total serum IGF-I and IGF-I/IGFBP-3 ratio (a surrogate marker of IGF-I biovailability) increased in the treatment group but IGF-I values still remained below normal limits in the treated patients. No differences were observed in body composition, muscle strength or muscle mass between groups. However, IGF-I therapy increased significantly serum albumin (P = 0.038) and this improvement correlated positively with variation of IGF-I/IGFBP-3 ratio. IGF-I treatment also tended to increase REE (P = 0.085); this difference was significant (P = 0.049) in the subgroup of alcoholic patients.

CONCLUSIONS

A short course of IGF-I increased albumin levels and tended to improve energy metabolism in liver cirrhosis. These findings warrant larger clinical trials to assess the clinical benefit of IGF-I in cirrhotic patients.

Insulin-like growth factor-I reverts testicular atrophy in rats with advanced cirrhosis

The pathogenesis of hypogonadism in cirrhosis is not completely understood. The levels of insulin-like growth factor-I (IGF-I), an anabolic factor with trophic actions on testes, are reduced in cirrhosis. This study was undertaken to evaluate whether rats with advanced cirrhosis develop hypogonadism and whether the administration of IGF-I exerts beneficial effects on testicular structure and function. Wistar rats with ascitic cirrhosis induced with CCl(4) were allocated into 2 groups (n = 10, each) to receive recombinant IGF-I (20 microg x kg(-1) x d(-1), subcutaneously) or vehicle for 3 weeks. Healthy rats receiving vehicle were used as the control group (n = 10). At baseline, both cirrhotic groups showed similar deterioration of liver function tests. Compared with controls, nontreated cirrhotic rats showed decreased serum levels of IGF-I (P <.05), reduced testicular size and weight (P <.001), and intense histopathological testicular abnormalities, including reduced tubular diameters (P <.001), loss of the germinal line (P <. 001), and diminutions in cellular proliferation, spermatogenesis (P <.001), and testicular transferrin expression (P <.001). In addition, low serum testosterone (P <.01) and high serum LH (P <.01) were present in untreated cirrhotic animals. Cirrhotic rats that received IGF-I showed full recovery of testicular size and weight and of all histopathological abnormalities (P <.001 to <.01 vs. nontreated cirrhotic rats; P = ns vs. controls). Serum levels of sex hormones tended to normalize. In conclusion, IGF-I deficiency may play a pathogenetic role in hypogonadism of cirrhosis. Low doses of IGF-I for a short period of time revert testicular atrophy and appear to improve hypogonadism in advanced experimental cirrhosis.

Impaired intestinal sugar transport in cirrhotic rats: correction by low doses of insulin-like growth factor I

BACKGROUND & AIMS

Malnutrition is a complication of liver cirrhosis accompanied by reduced insulin-like growth factor I (IGF-I) availability. The aim of this study was to analyze the effect of IGF-I on intestinal D-galactose absorption in cirrhotic rats.

METHODS

IGF-I (2 micrograms.100 g body wt-1.day-1) or saline were given for 14 days to rats in whom cirrhosis was induced with CCl4. Galactose transport and sodium-glucose/galactose-ligand transporter 1 (SGLT-1) expression were assessed in jejunal rings and in brush border membrane vesicles (BBMVs).

RESULTS

Compared with that in controls, galactose transport in everted jejunal rings was significantly reduced in cirrhotic rats but showed normal values after IGF-I treatment. The kinetic study of D-galactose uptake by BBMVs showed decreased maximal velocity (Vmax) and diminished transporter affinity in cirrhotic rats. These kinetic parameters reverted to normal after IGF-I treatment. Microvilli were significantly elongated in cirrhotic rats but of normal size in the IGF-I-treated group. The expression of SGLT-1 on BBMVs (Western blot) and on the luminal membrane of enterocytes (immunohistochemistry) was not reduced in cirrhotic animals compared with controls or IGF-treated cirrhotic rats.

CONCLUSIONS

Intestinal sugar transport is disturbed in experimental cirrhosis, and this alteration is corrected by IGF-I.

Insulin-Like Growth Factor-1 Deficiency and Cirrhosis Establishment

Cirrhosis represents the final stage of chronic liver damage, which can be due to different factors such as alcohol, metabolic syndrome with liver steatosis, autoimmune diseases, drugs, toxins, and viral infection, among others. Nowadays, cirrhosis is an important health problem and it is an increasing cause of morbidity and mortality, being the 14th most common cause of death worldwide. The physiopathological pathways that lead to fibrosis and finally cirrhosis partly depend on the etiology. Nevertheless, some common features are shared in this complex mechanism. Recently, it has been demonstrated that cirrhosis is a dynamic process that can be altered in order to delay or revert fibrosis. In addition, when cirrhosis has been established, insulin-like growth factor-1 (IGF-1) deficiency or reduced availability is a common condition, independently of the etiology of chronic liver damage that leads to cirrhosis. IGF-1 deprivation seriously contributes to the progressive malnutrition of cirrhotic patient, increasing the vulnerability of the liver to establish an inflammatory and oxidative microenvironment with mitochondrial dysfunction. In this context, IGF-1 deficiency in cirrhotic patients can justify some of the common characteristics of these individuals. Several studies in animals and humans have been done in order to test the replacement of IGF-1 as a possible therapeutic option, with promising results.

Altered liver gene expression in CCl4-cirrhotic rats is partially normalized by insulin-like growth factor-I

We have previously shown that the administration of low doses of insulin-like growth factor-I (IGF-I) to CCl4-cirrhotic rats improves liver function and reduces fibrosis. To better understand the mechanisms behind the hepatoprotective effects of IGF-I, and to identify those genes whose expression is affected in cirrhosis and after IGF-1 treatment, we have performed differential display of mRNA analysis by means of polymerase chain reaction (PCR) in livers from control and CCl4-cirrhotic rats treated or not with IGF-I. We have identified 16 genes that were up- or down-regulated in the cirrhotic liver. IGF-I treatment partially normalized the expression of eight of these genes, including serine proteinase inhibitors such as serpin-2 and alpha-1-antichymotripsin, alpha-1-acid glycoprotein, and alpha-2u-globulin. Additionally, we show that IGF-I enhanced the regenerative activity in the cirrhotic liver, as determined by the increased expression of the proliferating cell nuclear antigen (PCNA). Finally, IGF-I treatment partially restored the expression of growth hormone receptor (GHR) and the levels of global genomic DNA methylation, which are reduced in human and experimental cirrhosis. Taken together, our observations confirm the hepatoprotective effects of IGF-I, and suggest that this action can be exerted in part through the normalization of liver gene expression, growth hormone (GH) responsiveness and global genomic DNA methylation.

IGF-1 modulates gene expression of proteins involved in inflammation, cytoskeleton, and liver architecture

Even though the liver synthesizes most of circulating IGF-1, it lacks its receptor under physiological conditions. However, according to previous studies, a damaged liver expresses the receptor. For this reason, herein, we examine hepatic histology and expression of genes encoding proteins of the cytoskeleton, extracellular matrix, and cell-cell molecules and inflammation-related proteins. A partial IGF-1 deficiency murine model was used to investigate IGF-1's effects on liver by comparing wild-type controls, heterozygous igf1^+/-, and heterozygous mice treated with IGF-1 for 10 days. Histology, microarray for mRNA gene expression, RT-qPCR, and lipid peroxidation were assessed. Microarray analyses revealed significant underexpression of igf1 in heterozygous mice compared to control mice, restoring normal liver expression after treatment, which then normalized its circulating levels. IGF-1 receptor mRNA was overexpressed in Hz mice liver, while treated mice displayed a similar expression to that of the controls. Heterozygous mice showed overexpression of several genes encoding proteins related to inflammatory and acute-phase proteins and underexpression or overexpression of genes which coded for extracellular matrix, cytoskeleton, and cell junction components. Histology revealed an altered hepatic architecture. In addition, liver oxidative damage was found increased in the heterozygous group. The mere IGF-1 partial deficiency is associated with relevant alterations of the hepatic architecture and expression of genes involved in cytoskeleton, hepatocyte polarity, cell junctions, and extracellular matrix proteins. Moreover, it induces hepatic expression of the IGF-1 receptor and elevated acute-phase and inflammation mediators, which all resulted in liver oxidative damage.

Changes in intramitochondrial cardiolipin distribution in apoptosis-resistant HCW-2 cells, derived from the human promyelocytic leukemia HL-60

Using a cytofluorimetric approach, we studied intramitochondrial cardiolipin (CL) distribution in HCW-2 cells, an apoptosis-resistant clone of human HL-60 cells. In HL-60, about 50% of total CL is distributed in the outer leaflet of mitochondrial inner membrane, while in HCW-2 a significantly higher amount of CL (about 65%) is in that site. In basal conditions, HSW-2 cells also show a reduced mitochondrial membrane potential even if they are able to proliferate as the parental line. Taking into account the complex functions that CL plays in the regulation of mitochondrial activity, it is likely that HCW-2 could produce ATP utilizing more glycolytic pathways rather than mitochondrial respiratory chain.

Altered intestinal transport of amino acids in cirrhotic rats: the effect of insulin-like growth factor-I

The intestine is an important target organ for insulin-like growth factor-I (IGF-I), an anabolic hormone synthesized in the liver upon growth hormone (GH) stimulation. Levels of IGF-I are reduced in cirrhosis, and altered GH/IGF-I axis may contribute to malnutrition in cirrhotic patients. Our aim was to study Na(+)-dependent jejunal transport of amino acids (L-leucine, L-proline, L-glutamic acid, and L-cysteine) in cirrhotic rats and to analyze the effect of IGF-I on this function. IGF-I or saline was administered for 2 wk to rats with CCl(4)-induced cirrhosis and saline was administered to healthy control rats. Transport of amino acids was assessed in brush-border membrane vesicles (BBMV) using (14)C- or (35)S-labeled amino acids, and the kinetic constants V(max) and K(t) were determined. Na(+)-independent uptake of L-leucine, L-proline, L-glutamic acid, and L-cysteine by BBMV was similar in all groups. Na(+)-dependent uptake of all four amino acids was significantly diminished in cirrhotic rats compared with both controls and IGF-I-treated cirrhotic rats. The latter two groups exhibited similar V(max) and K(t), whereas untreated cirrhotic rats had reduced V(max) and increased K(t) compared with normal controls and IGF-I-treated cirrhotic animals. In conclusion, the transport of all four tested amino acids by BBMV is impaired in cirrhotic rats, and low doses of IGF-I can correct this defect.

Liver mitochondrial dysfunction is reverted by insulin-like growth factor II (IGF-II) in aging rats

BACKGROUND

Serum IGF-I and IGF-II levels decline with age. IGF-I replacement therapy reduces the impact of age in rats. We have recently reported that IGF-II is able to act, in part, as an analogous of IGF-I in aging rats reducing oxidative damage in brain and liver associated with a normalization of antioxidant enzyme activities. Since mitochondria seem to be the most important cellular target of IGF-I, the aim of this work was to investigate whether the cytoprotective actions of IGF-II therapy are mediated by mitochondrial protection.

METHODS

Three groups of rats were included in the experimental protocol young controls (17 weeks old); untreated old rats (103 weeks old); and aging rats (103 weeks old) treated with IGF-II (2 μg/100 g body weight and day) for 30 days.

RESULTS

Compared with young controls, untreated old rats showed an increase of oxidative damage in isolated mitochondria with a dysfunction characterized by: reduction of mitochondrial membrane potential (MMP) and ATP synthesis and increase of intramitochondrial free radicals production and proton leak rates. In addition, in untreated old rats mitochondrial respiration was not blocked by atractyloside. In accordance, old rats showed an overexpression of the active fragment of caspases 3 and 9 in liver homogenates. IGF-II therapy corrected all of these parameters of mitochondrial dysfunction and reduced activation of caspases.

CONCLUSIONS

The cytoprotective effects of IGF-II are related to mitochondrial protection leading to increased ATP production reducing free radical generation, oxidative damage and apoptosis.

Hematotesticular barrier is altered from early stages of liver cirrhosis: Effect of insulin-like growth factor 1

AIM: The pathogenesis of hypogonadism in liver cirrhosis is not well understood. Previous results from our laboratory showed that IGF-1 deficiency might play a pathogenetic role in hypogonadism of cirrhosis. The administration of IGF-1 for a short period of time reverted the testicular atrophy associated with advanced experimental cirrhosis. The aim of this study was to establish the historical progression of the described alterations in the testes, explore testicular morphology, histopathology, cellular proliferation, integrity of testicular barrier and hypophyso-gonadal axis in rats with no ascitic cirrhosis.

METHODS: Male Wistar rats with histologically-proven cirrhosis induced with carbon tetrachloride (CCl₄) for 11 wk, were allocated into two groups (n = 12, each) to receive recombinant IGF-1 (2 μg/100 g.d, sc) for two weeks or vehicle. Healthy rats receiving vehicle were used as control group (n = 12).

RESULTS: Compared to controls, rats with compensated cirrhosis showed a normal testicular size and weight and very few histopathological testicular abnormalities. However, these animals showed a significant diminution of cellular proliferation and a reduction of testicular transferrin expression. In addition, pituitary-gonadal axis was altered, with significant higher levels of FSH (P < 0.001 vs controls) and increased levels of LH in untreated cirrhotic animals. Interestingly, IGF-1 treatment normalized testicular transferrin expression and cellular proliferation and reduced serum levels of LH (P = ns vs controls, and P < 0.01 vs untreated cirrhotic group).

CONCLUSION: The testicular barrier is altered from an early stage of cirrhosis, shown by a reduction of transferrin expression in Sertoli cells, a diminished cellular proliferation and an altered gonadal axis. The treatment with IGF-1 could be also useful in this initial stage of testicular disorder associated with compensated cirrhosis.

Experimental approach to IGF-1 therapy in CCl4-induced acute liver damage in healthy controls and mice with partial IGF-1 deficiency

Background

Cell necrosis, oxidative damage, and fibrogenesis are involved in cirrhosis development, a condition in which insulin-like growth factor 1 (IGF-1) levels are diminished. This study evaluates whether the exogenous administration of low doses of IGF-1 can induce hepatoprotection in acute carbon tetrachloride (CCl₄)-induced liver damage compared to healthy controls (Wt Igf^+/+). Additionally, the impact of IGF-1 deficiency on a damaged liver was investigated in mice with a partial deficit of this hormone (Hz Igf1^+/−).

Methods

Three groups of 25 ± 5-week-old healthy male mice (Wt Igf^+/+) were included in the protocol: untreated controls (Wt). Controls that received CCl₄ (Wt + CCl₄) and Wt + CCl₄ were treated subcutaneously with IGF-1 (2 µg/100 g body weight/day) for 10 days (Wt + CCl₄ + IGF1). In parallel, three IGF-1-deficient mice (Hz Igf1^+/−) groups were studied: untreated Hz, Hz + CCl₄, and Hz + CCl₄ + IGF-1. Microarray and real-time quantitative polymerase chain reaction (RT-qPCR) analyses, serum aminotransferases levels, liver histology, and malondialdehyde (MDA) levels were assessed at the end of the treatment in all groups. All data represent mean ± SEM.

Results

An altered gene coding expression pattern for proteins of the extracellular matrix, fibrosis, and cellular protection were found, as compared to healthy controls, in which IGF-1 therapy normalized in the series including healthy mice. Liver histology showed that Wt + CCl₄ + IGF1 mice had less oxidative damage, fibrosis, lymphocytic infiltrate, and cellular changes when compared to the Wt + CCl₄. Moreover, there was a correlation between MDA levels and the histological damage score (Pearson’s r = 0.858). In the IGF-1-deficient mice series, similar findings were identified, denoting a much more vulnerable hepatic parenchyma.

Conclusions

IGF1 treatment improved the biochemistry, histology, and genetic expression of pro-regenerative and cytoprotective factors in both series (healthy and IGF-1-deficient mice) with acute liver damage, suggesting that low doses of IGF-1, in acute liver damage, could be a feasible therapeutic option.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1198-4) contains supplementary material, which is available to authorized users.

Fanconi Anemia and Laron Syndrome

BACKGROUND

Fanconi anemia (FA) is a condition characterized by genetic instability and short stature, which is due to growth hormone (GH) deficiency in most cases. However, no apparent relationships have been identified between FA complementation group genes and GH. In this study, we thereby considered an association between FA and Laron syndrome (LS) (insulin-like growth factor 1 [IGF-1] deficiency).

METHODS

A 21-year-old female Mexican patient with a genetic diagnosis of FA was referred to our research department for an evaluation of her short stature. Upon admission to our facility, her phenotype led to a suspicion of LS; accordingly, serum levels of IGF-1 and IGF binding protein 3 were analyzed and a GH stimulation test was performed. In addition, we used a next-generation sequencing approach for a molecular evaluation of FA disease-causing mutations and genes involved in the GH-IGF signaling pathway.

RESULTS

Tests revealed low levels of IGF-1 and IGF binding protein 3 that remained within normal ranges, as well as a lack of response to GH stimulation. Sequencing confirmed a defect in the GH receptor signaling pathway.

CONCLUSIONS

To the best of our knowledge, this study is the first to suggest an association between FA and LS. We propose that IGF-1 administration might improve some FA complications and functions based upon IGF-1 beneficial actions observed in animal, cell and indirect clinical models: erythropoiesis modulation, immune function improvement and metabolic regulation.

Mexican case report of a never-treated Laron syndrome patient evolving to metabolic syndrome, type 2 diabetes, and stroke

Glucose and lipid profile together with blood pressure should always be considered for low sera‐IGF‐1 patients. Even when adulthood is reached, IGF‐1 therapy in these patients should be pursued as metabolic and protective cellular effects could be triggered. Real incidence of growth hormone insensitivity is still to be uncovered.

Growth hormone insensitivity: Mexican case report

Herein, we present a 14-year-old patient with short stature (134 cm) referred from Paediatrics to our department for complementary evaluation since growth hormone (GH) treatment failed to show any improvement. He was born premature and small for gestational age. Genital examination classified the patient as Tanner I-II with small penis and testicular size for his age. Biochemical analyses revealed normal GH levels with low serum insulin-like growth factor-1 (IGF-1). Molecular diagnosis confirmed several mutations in IGF1R and IGFALS, and so he was diagnosed with Laron Syndrome or GH insensibility and treated with IGF-1 substitutive therapy.

Learning points

Evaluation of the GH/IGF-1 axis when short stature does not respond to conservative treatment must be included in the ordinary practice.Laron Syndrome real incidence should be calculated once undiagnosed cases arise, as treatment, due to lack of market, is unaffordable.Even when adulthood is reached, and no longitudinal growth can be achieved, still IGF-1 treatment in Laron Syndrome patients should be pursued as metabolic and protective derangements could arise.

Primary growth hormone insensitivity and psychomotor delay

We report a case of short stature irresponsive to growth hormone (GH) replacement therapy. Low GH response to provocative tests and undetectable IGF-1 levels had suggested GH deficiency, while response to therapy indicated GH insensitivity. Molecular evaluation of the GH/IGF-1 axis should be performed in these cases to improve diagnosis and therapy.

A 42-Year-Old Woman with Untreated Growth Hormone Insensitivity, Diabetic Retinopathy, and Gene Sequencing Identifies a Variant of Laron Syndrome

Patient: Female, 42

Final Diagnosis: Never-treated growth hormone insensitivity due to IGF-1 deprivation

Symptoms: Cataracts • mammary underdevelopment • severe hearing loss

Medication: —

Clinical Procedure: Early detection of IGF-1 deprivation and urgent consensus for current diagnosi

Specialty: Endocrinology and Metabolic