Altered liver expression of genes involved in lipid and glucose metabolism in mice with partial IGF-1 deficiency: an experimental approach to metabolic syndrome

When IGF-1 Meets Metabolic Inflammation and Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder associated with insulin resistance (IR) and hyperandrogenaemia (HA). Metabolic inflammation (MI), characterized by a chronic low-grade inflammatory state, is intimately linked with chronic metabolic diseases such as IR and diabetes and is also considered an essential factor in the development of PCOS. Insulin-like growth factor 1 (IGF-1) plays an essential role in PCOS pathogenesis through its multiple functions in regulating cell proliferation metabolic processes and reducing inflammatory responses. This review summarizes the molecular mechanisms by which IGF-1, via MI, participates in the onset and progression of PCOS, aiming to provide insights for studies and clinical treatment of PCOS.

Gualou-Xiebai-Banxia-Tang regulates liver-gut axis to ameliorate Metabolic Syndrome in HFD-fed mice

BACKGROUND

Metabolic syndrome (MetS), characterized by obesity, hyperglycemia, and abnormal blood lipid levels, is the pathological basis of many cardiovascular diseases. Gualou-Xiebai-Banxia-Tang decoction (GT) was first described in the Synopsis of the Golden Chamber, the earliest traditional Chinese medicine (TCM) monograph on diagnosis and treatment of miscellaneous diseases in China. According to TCM precepts, based on its ability to activate yang to release stagnation, activate qi to reduce depression, remove phlegm, and broaden the chest, GT has been used for more than 2,000 years to treat cardiovascular ailments. However, the molecular bases of its therapeutic mechanisms remain unclear.

PURPOSE

The aim of this study was to identify lipid- and glucose-related hepatic genes differentially regulated by GT, and to assess GT impact on gut microbiota composition, in mice with high-fat diet (HFD)-induced MetS.

STUDY DESIGN AND METHODS

ApoE-/- mice were fed with an HFD for 24 weeks, with or without concurrent GT supplementation, to induce MetS. At the study's end, body weight, visceral fat weight, blood lipid levels, and insulin sensitivity were measured, and histopathological staining was used to evaluate hepatosteatosis and intestinal barrier integrity. Liver transcriptomics was used for analysis of differentially expressed genes in liver and prediction of relevant regulatory pathways. Hepatic lipid/glucose metabolism-related genes and proteins were detected by RT-qPCR and western blotting. Gut microbial composition was determined by 16S rRNA gene sequencing.

RESULTS

GT administration reduced MetS-related liver steatosis and weight gain, promoted insulin sensitivity and lipid metabolism, and beneficially modulated gut microbiota composition by decreasing the relative abundance of g_Lachnospiraceae_NK4A136_group and increasing the relative abundance of g_Alistipes. Liver transcriptomics revealed that GT regulated the expression of genes related to lipid and glucose metabolism (Pparγ, Igf1, Gpnmb, and Trem2) and of genes encoding chemokines/chemokine receptors (e.g. Cxcl9 and Cx3cr1). Significant, positive correlations were found for Ccr2, Ccl4, Ccr1, and Cx3cr1 and the g_Lachnospiraceae_NK4A136_group, and between Cxcl9, Ccr2, Ccl4, and Cx3cr1 and g_Desulfovibrio. GT treatment downregulated the protein expressions of SCD1 and CX3CR1 and upregulated the expression of PCK1 protein.

CONCLUSION

GT supplementation alleviates HFD-induced MetS in mice by improving hepatic lipid and glucose metabolism. The anti-metabolic syndrome effects of GT may be related to the regulation of the gut-liver axis.

Glucocorticoids and intrauterine programming of nonalcoholic fatty liver disease

Accumulating epidemiological and experimental evidence indicates that nonalcoholic fatty liver disease (NAFLD) has an intrauterine origin. Fetuses exposed to adverse prenatal environments (e.g., maternal malnutrition and xenobiotic exposure) are more susceptible to developing NAFLD after birth. Glucocorticoids are crucial triggers of the developmental programming of fetal-origin diseases. Adverse intrauterine environments often lead to fetal overexposure to maternally derived glucocorticoids, which can program fetal hepatic lipid metabolism through epigenetic modifications. Adverse intrauterine environments program the offspring's glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis, which contributes to postnatal catch-up growth and disturbs glucose and lipid metabolism. These glucocorticoid-driven programming alterations increase susceptibility to NAFLD in the offspring. Notably, after delivery, offspring often face an environment distinct from their in utero life. The mismatch between the intrauterine and postnatal environments can serve as a postnatal hit that further disturbs the programmed endocrine axes, accelerating the onset of NAFLD. In this review, we summarize the current epidemiological and experimental evidence demonstrating that NAFLD has an intrauterine origin and discuss the underlying intrauterine programming mechanisms, focusing on the role of overexposure to maternally derived glucocorticoids. We also briefly discuss potential early life interventions that may be beneficial against fetal-originated NAFLD.

Molecular phenotypes of bovine blastocyst derived from in vitro-matured oocyte supplemented with PAPP-A

Insulin-like growth factor-1 (IGF-1) regulates cellular lipid content, whereas pregnancy-associated plasma protein-A (PAPP-A) increases IGF-1 bioavailability. Using in vitro-matured cumulus-oocyte complexes, we aimed to evaluate the impact of PAPP-A on the blastocyst lipid content, embryo cryotolerance and embryonic transcriptional profile. We determined that PAPP-A did not affect the lipid content of oocytes, blastocysts, or blastocyst yield (P > 0.05). However, PAPP-A modulated the embryo transcriptional profiles by downregulating PPARGC1A and AKR1B1, which are related to lipid metabolism; CASP9, a pro-apoptotic gene; and IFN-τ, a marker of embryo quality (P < 0.05). Furthermore, the use of PAPP-A improved blastocyst re-expansion in the first 3 h of culture after vitrification (P < 0.05). Although PAPP-A did not affect the blastocyst lipid content or embryo production, we suggest that embryonic transcriptional modulation could contribute to maintain the balance in embryo lipid metabolism. Furthermore, PAPP-A's approach seems to control key intracellular pathways that improve post-cryopreservation development of blastocysts.

IGF-1 and IGFBP3 as indirect markers of hepatic insulin resistance and their relation to metabolic syndrome parameters in liver steatosis patients

Objective. The aim of the present study was to assess insulin-like growth factor 1 (IGF-1) and IGF-binding protein 3 (IGFBP3) as markers of insulin resistance in patients with prediabetes and type 2 diabetes mellitus (TDM2). Patients and Methods. This observational clinical study included 76 obese/overweight patients at the age of 45-75 years with T2DM on oral diabetic medication and ultrasonographically or by a computerized tomography (CT) diagnosed liver steatosis. Correlation analysis was performed between plasma levels of insulin, C-peptide, IGF-1, IGFBP3 and HOMA indexes on the one hand and between plasma levels of ALT, AST, triglyceride, cholesterol, and HDL cholesterol and body mass index (BMI) of patients on the other hand. In case of significant partial correlation coefficients, a multiple linear regression model with IGF-1 and IGFBP3 used as outcome variables adjusted for age and sex groups was calculated. According to these regression models, ROC curves were prepared with HOMA index=3 used as a classificator of insulin resistance. Results. Significant correlation was found between C-peptide and IGF-1 (r=0.24, p≤0.05), C-peptide and IGFBP3 (r=0.24, p≤0.05), IGFBP3 and cholesterol (r=0.22, p≤0.05) IGFBP3 and ALT (r=0.19, p≤0.05), HOMA index and triglycerides (r=0.22, p≤0.05), and HOMA index and ALT (r=0.23, p≤0.05). Significant correlation adjusted for age and gender was found between C-peptide and IGF-1 plasma levels (R2=0.20, p<0.05) with AUROC 0.685 (p≤0.01) and C-peptide and IGFBP3 plasma levels (R2=0.28, p<0.05) with AUROC 0.684 (p≤0.01). Significant correlation adjusted for age and gender was found between triglyceride and IGFBP3 plasma levels (R2=0.28, p<0.05) with AUROC 0.616 (p≤0.01). After the distribution of patients according to their IGFBP3 levels, we found a difference between the 1st and the 4th quartiles in terms of triglyceride levels. Conclusion. Our results demonstrate a fundamental role of IGF-1 and IGFBP3 in the patho-physiology of hepatic insulin resistance and suggest them as indirect indicators of the hepatic insulin resistance.

PSRC1 May Affect Coronary Artery Disease Risk by Altering CELSR2, PSRC1, and SORT1 Gene Expression and Circulating Granulin and Apolipoprotein B Protein Levels

Objective

The aim of the study was to identify additional factors that contributed to coronary artery disease (CAD).

Methods

We conducted integrative analysis on publicly available data from genome-wide association studies and quantitative trait locus studies by employing Mendelian randomization methods to examine the associations of gene expression in liver cells and circulating protein levels with LDL-C and CAD.

Results

We found that the mRNA expression levels of CELSR2, PSRC1, SORT1, SYPL2, RHD, RHCE, ANGPTL3, ATXN7L2, DNAH11, FADS3, ST3GAL4, NYNRIN, CETP, EFCAB13, and SPTLC3 were significantly associated with LDL-C. The expression levels of SORT1, PSRC1, and CELSR2 in liver cells were significantly associated with CAD. Higher expression levels of SORT1, PSRC1, and CELSR2 in the liver were significantly associated with lower circulating LDL-C levels and CAD risk. PSRC1 variants were strongly associated with SORT1, PSRC1, and CELSR2 gene expression in liver cells. Higher circulating granulin and apolipoprotein B levels, which were strongly affected by PSRC1 variants, were significantly associated with higher LDL-C levels and CAD risk, with odds ratios of 1.15 (1.10–1.19) and 1.45 (1.21–1.74), respectively.

Conclusion

This study showed that regulatory SNPs in PSRC1 may affect CAD risk by altering CELSR2, PSRC1, and SORT1 gene expression in liver cells and circulating granulins and apolipoprotein B proteins.

Impact of oral nutritional supplements (ONS) on growth outcomes and IGF-1 level in underweight older children and young adolescents (5-14 years) with short stature and no systemic disease: High versus normal calories density formula

Objectives:

This controlled trial investigated the effects of energy-dense pediatric oral nutritional supplements ONS versus standard ONS in pediatric patients requiring oral nutritional support for low body mass index (BMI) or weight gain per day (WGD) below the average for age and sex.

Patients and Methods:

34 children and adolescents (mean age 10.2 years) with faltering growth requiring ONS were randomized to cONS (n =22) or sONS (n = 12) for a year. We recorded their weight (WT), height (HT) and calculated height growth velocity (GV), Ht-SDS, BMI, WGD, every 3 months for a year.

Results:

The WGD, height growth velocity (GV: cm/year), and Ht-SDS increased significantly, in both groups, during the year of ONS. The use of the cONS resulted in significantly greater mean total WGD and BMI-SDS after 6 months and 1 year, compared to the sONS group. The increase in IGF1-SDS was significantly higher in the cONS groups versus the sONS group. Moreover, the WGD was correlated significantly with the height GV during the year of ONS intake.

Conclusions:

ONS improved the growth of underweight old children and adolescents who had no systemic illness. There was a significantly higher WGD and BMI-SDS in the group on cONS compared to those on sONS. In both groups, long-term use of ONS significantly improved Ht-SDS. (www.actabiomedica.it)

Insulin-Like Growth Factor 1 (IGF-1) Signaling in Glucose Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common aggressive carcinoma types worldwide, characterized by unfavorable curative effect and poor prognosis. Epidemiological data re-vealed that CRC risk is increased in patients with metabolic syndrome (MetS) and its serum components (e.g., hyperglycemia). High glycemic index diets, which chronically raise post-prandial blood glucose, may at least in part increase colon cancer risk via the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. Hyperactivated glucose uptake and aerobic glycolysis (the Warburg effect) are considered as a one of six hallmarks of cancer, including CRC. However, the role of insulin/IGF-1 signaling during the acquisition of the Warburg metabolic phenotypes by CRC cells is still poorly understood. It most likely results from the interaction of multiple processes, directly or indirectly regulated by IGF-1, such as activation of PI3K/Akt/mTORC, and Raf/MAPK signaling pathways, activation of glucose transporters (e.g., GLUT1), activation of key glycolytic enzymes (e.g., LDHA, LDH5, HK II, and PFKFB3), aberrant expression of the oncogenes (e.g., MYC, and KRAS) and/or overexpression of signaling proteins (e.g., HIF-1, TGF-β1, PI3K, ERK, Akt, and mTOR). This review describes the role of IGF-1 in glucose metabolism in physiology and colorectal carcinogenesis, including the role of the insulin/IGF system in the Warburg effect. Furthermore, current therapeutic strategies aimed at repairing impaired glucose metabolism in CRC are indicated.

Insulin-like growth factor-1 short-period therapy stimulates bone marrow cells in obese swiss mice

Bone marrow cells (BMCs) from obese Swiss mice fed with Western diet show mitochondrial dysfunction. Obesity interferes with BMCs disrupting energetic metabolism, stimulating apoptosis, and reducing cell proliferation since adipose tissue releases inflammatory adipokines into the medullar microenvironment. These changes lead to reduction of BMC differentiation capacity and hematopoiesis impairment, a process responsible for blood cell continuous production through hematopoietic stem cells (HSCs). This work aimed to analyze the effects of IGF-1 therapy on BMC viability in Western diet-induced obesity, in vivo. We observed that after only 1 week of treatment, obese Swiss mice presented reduced body weight and visceral fat and increased mitochondrial oxidative capacity and coupling, indicating mitochondrial function improvement. In addition, IGF-1 was able to reduce apoptosis of total BMCs, stem cell subpopulations (hematopoietic and mesenchymal), and leukocytes, restoring all progenitor hematopoietic lineages. The treatment also contributed to increase proliferative capacity of hematopoietic stem cells and leukocytes, keeping the hematopoietic and immune systems balanced. Therefore, we conclude that IGF-1 short period therapy improved BMC survival, proliferation, and differentiation capacity in obese Swiss mice.

Oxidative Stress and Low-Grade Inflammation in Polycystic Ovary Syndrome: Controversies and New Insights

The pathophysiology of Polycystic Ovary Syndrome (PCOS) is quite complex and different mechanisms could contribute to hyperandrogenism and anovulation, which are the main features of the syndrome. Obesity and insulin-resistance are claimed as the principal factors contributing to the clinical presentation; in normal weight PCOS either, increased visceral adipose tissue has been described. However, their role is still debated, as debated are the biochemical markers linked to obesity per se. Oxidative stress (OS) and low-grade inflammation (LGI) have recently been a matter of researcher attention; they can influence each other in a reciprocal vicious cycle. In this review, we summarize the main mechanism of radical generation and the link with LGI. Furthermore, we discuss papers in favor or against the role of obesity as the first pathogenetic factor, and show how OS itself, on the contrary, can induce obesity and insulin resistance; in particular, the role of GH-IGF-1 axis is highlighted. Finally, the possible consequences on vitamin D synthesis and activation on the immune system are briefly discussed. This review intends to underline the key role of oxidative stress and low-grade inflammation in the physiopathology of PCOS, they can cause or worsen obesity, insulin-resistance, vitamin D deficiency, and immune dyscrasia, suggesting an inverse interaction to what is usually considered.

IGF-1 induces cellular senescence in rat articular chondrocytes via Akt pathway activation

Cellular senescence decreases cell proliferation over time and is characterized by typical markers, including larger cell volume, a flattened morphology, irreversible cell cycle arrest, augmentation of senescence-associated β-galactosidase (SA-β-gal) activity and senescence-associated secretory phenotype. A variety of factors are implicated in the process of cellular aging, which mediates an organisms' lifespan. Insulin-like growth factor-1 (IGF-1) serves an essential role in regulating cell growth, division, proliferation and senescence. In the present study, the role of IGF-1 and the downstream Akt signaling pathway in rat articular chondrocyte senescence was assessed. The results of the current study demonstrated that IGF-1 promoted cellular senescence in rat articular chondrocytes via activation of SA-β-gal and the upregulation of p53 and p21 mRNA and protein levels. IGF-1 enhanced Akt phosphorylation and treatment with Akt inhibitor, MK-2206, significantly suppressed the induction of these markers. Overall, the results indicated the involvement of IGF-1 and Akt in senescence exhibited by rat articular chondrocytes.

Associations between IGF1, IGFBP2 and TGFß3 Genes Polymorphisms and Growth Performance of Broiler Chicken Lines

Marker-assisted selection based on fast and accurate molecular analysis of individual genes is considered an acceptable tool in the speed-up of the genetic improvement of production performance in chickens. The objective of this study was to detect the single nucleotide polymorphisms (SNPs) in the IGF1, IGFBP2 and TGFß3 genes, and to investigate their associations with growth performance (body weight (BW) and average daily gain (ADG) at 14, 21, 28, 35 and 42 days of age) and carcass traits in broilers. Performance (carcass) data (weight before slaughter; weights of the trunk, giblets, abdominal fat, breast muscle and thigh muscle; slaughter value and slaughter percentage), as well as blood samples for DNA extraction and SNP analysis, were obtained from 97 chickens belonging to two different lines (Hubbard F15 and Cobb E) equally divided between the two sexes. The genotypes were detected using polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) methods with specific primers and restrictase for each gene. The statistical analysis discovered significant associations (p < 0.05) between the TGFβ3 SNP and the following parameters: BW at 21, 28 and 35 days, trunk weight and slaughter value. Association analysis of BWs (at 21, 28 and 35 days) and SNPs was always significant for codominant, dominant and overdominant genetic models, showing a possible path for genomic selection in these chicken lines. Slaughter value was significant for codominant, recessive and overdominant patterns, whereas other carcass traits were not influenced by SNPs. Based on the results of this study, we suggested that the TGFβ3 gene could be used as a candidate gene marker for chicken growth traits in the Hubbard F15 and Cobb E population selection programs, whereas for carcass traits further investigation is needed.

Disparate Central and Peripheral Effects of Circulating IGF-1 Deficiency on Tissue Mitochondrial Function

Age-related decline in circulating levels of insulin-like growth factor (IGF)-1 is associated with reduced cognitive function, neuronal aging, and neurodegeneration. Decreased mitochondrial function along with increased reactive oxygen species (ROS) and accumulation of damaged macromolecules are hallmarks of cellular aging. Based on numerous studies indicating pleiotropic effects of IGF-1 during aging, we compared the central and peripheral effects of circulating IGF-1 deficiency on tissue mitochondrial function using an inducible liver IGF-1 knockout (LID). Circulating levels of IGF-1 (~ 75%) were depleted in adult male Igf1^f/f mice via AAV-mediated knockdown of hepatic IGF-1 at 5 months of age. Cognitive function was evaluated at 18 months using the radial arm water maze and glucose and insulin tolerance assessed. Mitochondrial function was analyzed in hippocampus, muscle, and visceral fat tissues using high-resolution respirometry O2K as well as redox status and oxidative stress in the cortex. Peripherally, IGF-1 deficiency did not significantly impact muscle mass or mitochondrial function. Aged LID mice were insulin resistant and exhibited ~ 60% less adipose tissue but increased fat mitochondrial respiration (20%). The effects on fat metabolism were attributed to increases in growth hormone. Centrally, IGF-1 deficiency impaired hippocampal-dependent spatial acquisition as well as reversal learning in male mice. Hippocampal mitochondrial OXPHOS coupling efficiency and cortex ATP levels (~ 50%) were decreased and hippocampal oxidative stress (protein carbonylation and F₂-isoprostanes) was increased. These data suggest that IGF-1 is critical for regulating mitochondrial function, redox status, and spatial learning in the central nervous system but has limited impact on peripheral (liver and muscle) metabolism with age. Therefore, IGF-1 deficiency with age may increase sensitivity to damage in the brain and propensity for cognitive deficits. Targeting mitochondrial function in the brain may be an avenue for therapy of age-related impairment of cognitive function. Regulation of mitochondrial function and redox status by IGF-1 is essential to maintain brain function and coordinate hippocampal-dependent spatial learning. While a decline in IGF-1 in the periphery may be beneficial to avert cancer progression, diminished central IGF-1 signaling may mediate, in part, age-related cognitive dysfunction and cognitive pathologies potentially by decreasing mitochondrial function.

Low-density lipoprotein cholesterol levels are associated with insulin-like growth factor-1 in short-stature children and adolescents: a cross-sectional study

BACKGROUND

Elevated low-density lipoprotein cholesterol (LDL-C) levels in childhood have recently been found to be the strongest predictive risk factor for coronary artery disease in adulthood. There is an increased level of LDL-C in children and adolescents with short stature. However, the underlying factors associated with increased LDL-C levels in children and adolescents with short stature are unknown. In addition, the insulin-like growth factor 1 (IGF-1) level in the short-stature population is usually below the normal reference range. The aim of this study was to investigate the relationship between IGF-1 standard deviation score (IGF-1 SDS) and LDL-C level in children and adolescents with short stature.

METHODS

A cross-sectional study was conducted in a single centre of China, 557 short-stature children and adolescents whose height SDS was lower than - 2 SD after adjustment for age and gender were included. The related clinical and laboratory examinations, including anthropometric parameters, lipid profiles, IGF-1 levels and the levels of other cofactors, were assessed in all participants.

RESULTS

The univariate analysis results showed a significant negative correlation between IGF-1 SDS and LDL-C levels (P = 0.006). Furthermore, a nonlinear relationship was observed between IGF-1 SDS and LDL-C by smooth curve fitting after adjusting for possible confounders. A multivariate piecewise linear regression model revealed a significant negative correlation between IGF-1 SDS and LDL-C when the IGF-1 level was greater than - 2 SDS (β - 0.07, 95% CI -0.12, - 0.02; P = 0.006). However, we did not observe a significant relationship between IGF-1 SDS and LDL-C when the IGF-1 level was lower than - 2 SDS (β 0.08, 95% CI -0.02, 0.17; P = 0.119).

CONCLUSION

This study demonstrated a nonlinear relationship between IGF-1 and LDL-C independent of other potential confounding factors, suggesting that circulating IGF-1 may contribute to the regulation of LDL-C levels, thus meriting further investigation.

Insulin-Like Growth Factor 1 in the Cardiovascular System

Non-communicable diseases, such as cardiovascular diseases, are the leading cause of mortality worldwide. For this reason, a tremendous effort is being made worldwide to effectively circumvent these afflictions, where insulin-like growth factor 1 (IGF1) is being proposed both as a marker and as a central cornerstone in these diseases, making it an interesting molecule to focus on. Firstly, at the initiation of metabolic deregulation by overfeeding, IGF1 is decreased/inhibited. Secondly, such deficiency seems to be intimately related to the onset of MetS and establishment of vascular derangements leading to atherosclerosis and finally playing a definitive part in cerebrovascular and myocardial accidents, where IGF1 deficiency seems to render these organs vulnerable to oxidative and apoptotic/necrotic damage. Several human cohort correlations together with basic/translational experimental data seem to confirm deep IGF1 implication, albeit with controversy, which might, in part, be given by experimental design leading to blurred result interpretation.

Enhanced early-life nutrition upregulates cholesterol biosynthetic gene expression and Sertoli cell maturation in testes of pre-pubertal Holstein bulls

Well-fed prepuberal Holstein bulls had larger testes, earlier puberty, higher LH, testosterone and IGF-1, earlier and more proliferating and differentiating Sertoli cells, and greater sperm production potential. The objective was to determine effects of pre-pubertal nutrition on mRNA expression of testicular genes. Holstein bull calves were fed high or low diets (20 or 12% crude protein, respectively and 71.6 or 64.4% Total Digestible Nutrients) from 2 wk, castrated at 8, 16, 24 and 32 wk and testicular mRNA extracted and sequenced. Differential expression of genes mainly occurred at 16 and 24 wk. At 16 wk, functional analysis (DAVID) of DE mRNA revealed common biological processes including "cholesterol" and "fatty acid biosynthesis," with most genes (including HMGCR, HMGCS1, HSD17) upregulated in high-diet bulls (P < 0.05). Major pathways enriched at 16 wk were "cholesterol biosynthesis", "steroid metabolism" and "activation of gene expression by Sterol regulatory element binding protein (SREBP)" (P < 0.05). In high-diet bulls, mature Sertoli cell marker Connexin 43, was upregulated at 16 wk and immature Sertoli cell marker (AMH) downregulated at 24 wk. There was an indirect interaction between insulin family receptor and most upregulated cholesterol biosynthesis genes. Pre-pubertal nutrition enhanced testicular cholesterol/steroid biosynthesis and Sertoli cell maturation.

Metabolic and immunological assessment of small-for-gestational-age children during one-year treatment with growth hormone: the clinical impact of apolipoproteins

Children born small for gestational age (SGA) are at a higher risk for metabolic disorders later in life. In this study, we aimed to characterize young SGA children without catch-up growth and evaluate the effects of GH treatment on endocrinological, metabolic, and immunological parameters. Study design is a one-year single hospital-based study included prospective observation of SGA patients during 12 months of GH treatment. Clinical and laboratory profiles of SGA children at baseline were compared with controls born appropriate size for age. Twenty-six SGA children (median age, 3.4 years) and 26 control children (median age, 3.8 years) were enrolled. Anthropometric, hematologic, biochemical, immunological, and endocrinological parameters were assessed at baseline and 1, 3, 6, 9, and 12 months after the start of GH treatment. As a result, median height SD score (SDS) of SGA children increased by +0.42 with 12-month GH treatment. Body mass index SDS was lower in SGA children than in controls. Serum apolipoprotein A1 increased, whereas apolipoprotein B decreased during GH treatment. Serum leptin and resistin levels, which were lower in SGA children than in controls at baseline, did not change remarkably with GH treatment. Monocyte counts, which were lower in SGA patients at baseline, increased after GH treatment. Neutrophil counts significantly increased after GH treatment. Natural killer cell ratios, which were higher in SGA patients, decreased after GH treatment. In conclusion, there was no evidence suggesting metabolic abnormalities in SGA children. Serum apolipoprotein changes might predict the beneficial role of GH treatment in lowering cardiometabolic risk.

Arginine reverses growth hormone resistance through the inhibition of toll-like receptor 4-mediated inflammatory pathway

OBJECTIVE

Growth hormone stimulates growth by increasing insulin-like growth factor 1 expression and secretion. In the presence of insufficient nutrients, GH increases, whereas IGF-1 expression becomes severely suppressed, leading to GH resistance. This study aimed to explore the effect of arginine (Arg) on GH resistance during malnutrition and to describe its underlying mechanism.

METHODS

C57BL/6J mice were injected intraperitoneally with Arg for 1h or subjected to caloric restriction with Arg supplement in drinking water for 18days. HepG2 cells were exposed to different Arg concentrations for 24h. Signaling pathway agonists/inhibitors, siRNA, and overexpression plasmids were used to investigate the underlying molecular mechanism. Liver-specific toll-like receptor (TLR4) knockout mice were utilized to clarify the role of TLR4 in Arg-induced IGF-I expression and secretion.

RESULTS

Arg inhibited the TLR4 downstream pathway by binding to TLR4 and consequently activated Janus kinase 2/signal transducer and activator of transcription 5 signaling pathway. As a result, IGF-1 transcription and secretion increased. Arg activity was absent in liver-specific TLR4 knockout mice and was greatly suppressed in liver with overexpressed TLR4, suggesting that hepatic TLR4 was required and sufficient to induce GH resistance. By contrast, the mammalian target of rapamycin pathway was unnecessary for Arg activity. Arg not only significantly increased IGF-1 expression and secretion under acute fasting and chronic CR conditions but also attenuated body weight loss.

CONCLUSIONS

Our results demonstrate a previously unappreciated pathway involving Arg that reverses GH resistance and alleviates malnutrition-induced growth restriction through the inhibition of TLR4-mediated inflammatory pathway.

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.

Partial IGF-1 deficiency is sufficient to reduce heart contractibility, angiotensin II sensibility, and alter gene expression of structural and functional cardiac proteins

Circulating levels of IGF-1 may decrease under several circumstances like ageing, metabolic syndrome, and advanced cirrhosis. This reduction is associated with insulin resistance, dyslipidemia, progression to type 2 diabetes, and increased risk for cardiovascular diseases. However, underlying mechanisms between IGF-1 deficiency and cardiovascular disease remain elusive.

The specific aim of the present work was to study whether the partial IGF-1 deficiency influences heart and/or coronary circulation, comparing vasoactive factors before and after of ischemia-reperfusion (I/R). In addition, histology of the heart was performed together with cardiac gene expression for proteins involved in structure and function (extracellular matrix, contractile proteins, active peptides); carried out using microarrays, followed by RT-qPCR confirmation of the three experimental groups. IGF-1 partial deficiency is associated to a reduction in contractility and angiotensin II sensitivity, interstitial fibrosis as well as altered expression pattern of genes involved in extracellular matrix proteins, calcium dynamics, and cardiac structure and function.

Although this work is descriptive, it provides a clear insight of the impact that partial IGF-1 deficiency on the heart and establishes this experimental model as suitable for studying cardiac disease mechanisms and exploring therapeutic options for patients under IGF-1 deficiency conditions.

The single IGF-1 partial deficiency is responsible for mitochondrial dysfunction and is restored by IGF-1 replacement therapy

BACKGROUND & AIMS

We previously described in cirrhosis and aging, both conditions of IGF-1 deficiency, a clear hepatic mitochondrial dysfunction with increased oxidative damage. In both conditions, the hepatic mitochondrial function was improved with low doses of IGF-1. The aim of this work was to explore if the only mere IGF-1 partial deficiency, without any exogenous insult, is responsible for hepatic mitochondrial dysfunction.

METHODS

Heterozygous (igf1^+/-) mice were divided into two groups: untreated and treated mice with low doses of IGF-1. WT group was used as controls. Parameters of hepatic mitochondrial function were determined by flow cytometry, antioxidant enzyme activities were determined by spectrophotometry, and electron chain transport enzyme levels were determined by immunohistochemistry and immunofluorescence analyses. Liver expression of genes coding for proteins involved in mitochondrial protection and apoptosis was studied by microarray analysis and RT-qPCR.

RESULTS

Hz mice showed a significant reduction in hepatic mitochondrial membrane potential (MMP) and ATPase activity, and an increase in intramitochondrial free radical production and proton leak rates, compared to controls. These parameters were normalized by IGF-1 replacement therapy. No significant differences were found between groups in oxygen consumption and antioxidant enzyme activities, except for catalase, whose activity was increased in both Hz groups. Relevant genes coding for proteins involved in mitochondrial protection and survival were altered in Hz group and were reverted to normal in Hz+IGF-1 group.

CONCLUSIONS

The mere IGF-1 partial deficiency is per se associated with hepatic mitochondrial dysfunction sensitive to IGF-1 replacement therapy. Results in this work prove that IGF-1 is involved in hepatic mitochondrial protection, because it is able to reduce free radical production, oxidative damage and apoptosis. All these IGF-1 actions are mediated by the modulation of the expression of genes encoding citoprotective and antiapoptotic proteins.

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.

Associations of lipid profiles with insulin resistance and β cell function in adults with normal glucose tolerance and different categories of impaired glucose regulation

Aims

To investigate the associations of dyslipidemia with insulin resistance and β cell function in individuals with normal glucose tolerance (NGT) and different categories of impaired glucose regulation (IGR).

Methods

544 subjects (365 with dyslipidemia and/or IGR and 179 with normal lipid and glucose tolerance) were enrolled in the study. All subjects underwent oral glucose tolerance test (OGTT). HOMA-IR was used to evaluate insulin sensitivity. Disposition index (DI) was used to evaluate β cell function. Multiple linear regression analysis was performed to assess correlations among lipid profiles, insulin resistance and β cell function.

Results

Among subjects with NGT, those with dyslipidemia had higher level of HOMA-IR but lower level of DI. While among subjects with different categories of IGR, those with dyslipidemia and CGI had significantly decreased DI. No obvious differences of insulin resistance or β cell function were found in IFG or IGT subjects with or without dyslipidemia. TG and HDL-C were correlated with HOMA-IR (β = 0.79, p <0.001; β = -0.38, p = 0.027, respectively, compared with subjects in the low level groups). Moreover, TG and TC were negatively correlated with DI (β = -2.17, p = 0.013; β = -2.01, p = 0.034 respectively, compared with subjects in the low level groups) after adjusting for confounding parameters.

Conclusions

Dyslipidemia induces insulin resistance and impaired β cell response to insulin resistance in individuals with NGT. Furthermore, dyslipidemia diminishes β cell function in subjects with CGI. TG and HDL-C were correlated with insulin resistance, and TG, TC were negatively correlated with β cell response to insulin resistance in non-diabetic individuals.

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.

Genetic risk variants for metabolic traits in Arab populations

Despite a high prevalence of metabolic trait related diseases in Arabian Peninsula, there is a lack of convincingly identified genetic determinants for metabolic traits in this population. Arab populations are underrepresented in global genome-wide association studies. We genotyped 1965 unrelated Arab individuals from Kuwait using Cardio-MetaboChip, and tested SNP associations with 13 metabolic traits. Models based on recessive mode of inheritance identified Chr15:40531386-rs12440118/ZNF106/W->R as a risk variant associated with glycated-hemoglobin at close to ‘genome-wide significant’ p-value and five other risk variants ‘nominally’ associated (p-value ≤ 5.45E-07) with fasting plasma glucose (rs7144734/[OTX2-AS1,RPL3P3]) and triglyceride (rs17501809/PLGRKT; rs11143005/LOC105376072; rs900543/[THSD4,NR2E3]; and Chr12:101494770/IGF1). Furthermore, we identified 33 associations (30 SNPs with 12 traits) with ‘suggestive’ evidence of association (p-value < 1.0E-05); 20 of these operate under recessive mode of inheritance. Two of these ‘suggestive’ associations (rs1800775-CETP/HDL; and rs9326246-BUD13/TGL) showed evidence at genome-wide significance in previous studies on Euro-centric populations. Involvement of many of the identified loci in mediating metabolic traits was supported by literature evidences. The identified loci participate in critical metabolic pathways (such as Ceramide signaling, and Mitogen-Activated Protein Kinase/Extracellular Signal Regulated Kinase signaling). Data from Genotype-Tissue Expression database affirmed that 7 of the identified variants differentially regulate the up/downstream genes that mediate metabolic traits.

Pathophysiologic Determination of Frostbite Under High Altitude Environment Simulation in Sprague-Dawley Rats

OBJECTIVES

Pathophysiologic changes of frostbite have been postulated but rarely understood, especially the changes caused by chilly high altitude environment. Therefore, we investigated the pathophysiologic changes of high altitude frostbite (HAF) caused by cold and hypoxia.

METHODS

Forty Sprague-Dawley rats were randomly divided into 5 equal groups, namely, control, superficial HAF (S-HAF), partial-thickness HAF (PT-HAF), full-thickness HAF (FT-HAF), and partial-thickness normal frostbite (PT-NF) groups. The S-HAF, PT-HAF, and FT-HAF groups were fed under hypobaric hypoxic conditions simulating an altitude of 5000 m. Then, the PT-NF, S-HAF, PT-HAF, and FT-HAF models were constructed by controlling the duration of the direct freezing by liquid nitrogen. Animal vital signs were measured after the operation, and histopathologic changes were observed after routine hematoxylin and eosin staining. In addition, the microcirculation of frostbite tissues was monitored and compared by contrast ultrasonography during wound healing.

RESULTS

The S-HAF, PT-HAF, and FT-HAF groups showed significant differences in the microcirculatory and histopathologic changes in the various tissue layers (P < .05). In addition, combined cold and hypoxia caused more damage to frostbite tissue than pure cold. The circulation recovery of HAF models was significantly slower relative to NF models (P < .05).

CONCLUSIONS

A safe and reproducible HAF model was proposed. More important, pathophysiologic determination of HAF provided the foundation and potential for developing novel and effective frostbite therapies.

Insulin-like growth factor 1 (IGF-1) therapy: Mitochondrial dysfunction and diseases

This review resumes the association between mitochondrial function and diseases, especially neurodegenerative diseases. Additionally, it summarizes the major role of IGF-1 as a mitochondrial protector, as studied in several experimental models (cirrhosis, aging …). The contribution of mitochondrial dysfunction to impairments in insulin metabolic signaling is also suggested by gene array analysis showing that reductions in gene expression, that regulates mitochondrial ATP production, are associated with insulin resistance and type 2 diabetes mellitus. Moreover, reductions in oxidative capacity of mitochondrial electron transport chain are manifested in obese, insulin-resistant and diabetic patients. Genetic and environmental factors, oxidative stress, and alterations in mitochondrial biogenesis can adversely affect mitochondrial function, leading to insulin resistance and several pathological conditions, such as type 2 diabetes. Finally, it remains essential to know the exact mechanisms involved in mitochondrial generation and metabolism, mitophagy, apoptosis, and oxidative stress to establish new targets in order to develop potentially effective therapies. One of the newest targets to recover mitochondrial dysfunction could be the administration of IGF-1 at low doses. In the last years, it has been observed that IGF-1 therapy has several beneficial effects: restores physiological IGF-1 levels; improves insulin resistance and lipid metabolism; exerts mitochondrial protection; and has hepatoprotective, neuroprotective, antioxidant and antifibrogenic effects. In consequence, treatment of mitochondrial dysfunctions with low doses of IGF-1 could be a powerful and useful effective therapy to restore normal mitochondrial functions.

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.