Association between serum growth hormone levels and nonalcoholic fatty liver disease: a cross-sectional study

Circulating and hepatic levels of growth differentiation factor 15 in patients with metabolic dysfunction-associated steatotic liver disease

AIM

Increased growth differentiation factor 15 (GDF15) may reflect impaired metabolic health and an inflammatory state in metabolic dysfunction-associated steatotic liver disease (MASLD). We investigated the role of GDF15 in histologically verified MASLD in a meal test (discovery) cohort (n = 20) and a prospective (validation) cohort with 2 years of follow-up (n = 276).

METHODS

Participants were evaluated clinically and histologically in both cohorts. Fibrosis severity was classified as no/mild (F0/F1) or significant (F2-4). Plasma GDF15 was measured by enzyme-linked immunosorbent assays and the SOMAScan platform. Hepatic GDF15 mRNA expression was analyzed by RNA in situ hybridization and bulk RNA-sequencing. In addition, we used data from public single-nucleus RNA-sequencing datasets.

RESULTS

In both cohorts, plasma GDF15 was increased in MASLD compared with healthy controls (p < 0.0001) with the highest levels in patients with significant fibrosis (area under the curve 0.83; 95% confidence interval [CI], 0.76-0.91). The GDF15 levels were unaffected by a standardized meal and there was no difference in peripheral or hepatic venous concentrations. After 2 years, the increase in GDF15 levels was reduced in patients treated with glucagon-like peptide receptor agonists (GLP-1-RA) compared to patients receiving lifestyle advice (-28%; 95% CI, -44 to -8; p = 0.01). Plasma GDF15 was associated with circulating insulin-like growth factor 1 and related proteins. Hepatic GDF15 mRNA was mainly expressed in hepatocytes and in cholangiocytes in fibrotic areas and was increased in MASLD (p = 0.02) with the highest expression in the group with steatohepatitis (p = 0.009).

CONCLUSIONS

Increased hepatic and circulating GDF15 are found in MASLD. Treatment with GLP-1-RA may reduce GDF15, possibly reflecting beneficial metabolic and inflammatory effects.

Risk factors and prediction model of metabolic disorders in adult patients with pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome (PSIS) is an infrequently occurring congenital condition, and there exists a dearth of systematic investigative work focusing on the clinical features and long-term outcomes in adult patients. Individuals who have reached adulthood with PSIS are at an increased risk of developing metabolic disorders, including metabolic syndrome (MS) and non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction associated fatty liver disease (MAFLD), which are also one of the main factors for the poor prognosis of these patients. An analysis was conducted on the clinical data of adult PSIS patients who visited the endocrinology department of the First Medical Center of the People's Liberation Army General Hospital from January 2005 to August 2023. Patients were grouped based on their MAFLD and MS status, and the differences in clinical characteristics and risk factors between the groups were analyzed. Machine learning models were used to construct a prediction model for the occurrence of MAFLD in adult PSIS patients and to analyze high-risk predictors. Out of 136 PSIS adult patients, 93.3% were male. The prevalence of MAFLD was 55.5%, and MS was 22.3%. Patients with a history of growth hormone (GH) treatment were less likely to develop MAFLD (P = 0.032). MAFLD patients exhibited higher rates of hypertension, hyperuricemia, obesity, MS, and dyslipidemia. Multiple risk factors may contribute to MS, while no significant link was found between MS and hormone replacement. However, GH non-treatment may serve as the notable predictor of MAFLD in PSIS patients revealed by the Ridge regression model of machine learning model with the highest predictive performance of a mean area under the curve (AUC) of 0.82. The prevalence of MS and MAFLD is high among adult patients with PSIS. Multiple risk factors may contribute to these two diseases, and after constructing a predictive model, we found that MAFLD may be closely linked to the previous lack of GH treatment.

Liver-specific actions of GH and IGF1 that protect against MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD; also known as nonalcoholic fatty liver disease) is a chronic condition associated with metabolic syndrome, a group of conditions that includes obesity, insulin resistance, hyperlipidaemia and cardiovascular disease. Primary growth hormone (GH) deficiency is associated with MASLD, and the decline in circulating levels of GH with weight gain might contribute to the development of MASLD. Raising endogenous GH secretion or administering GH replacement therapy in the context of MASLD enhances insulin-like growth factor 1 (IGF1) production and reduces steatosis and the severity of liver injury. GH and IGF1 indirectly control MASLD progression by regulating systemic metabolic function. Evidence supports the proposal that GH and IGF1 also have a direct role in regulating liver metabolism and health. This Review focuses on how GH acts on the hepatocyte in a sex-dependent manner to limit lipid accumulation, reduce stress, and promote survival and regeneration. In addition, we discuss how GH and IGF1 might regulate non-parenchymal cells of the liver to control inflammation and fibrosis, which have a major effect on hepatocyte survival and regeneration. Development of a better understanding of how GH and IGF1 coordinate the functions of specific, individual liver cell types might provide insight into the aetiology of MASLD initiation and progression and suggest novel approaches for the treatment of MASLD.

Growth hormone/insulin-like growth factor I axis in health and disease states: an update on the role of intra-portal insulin

Growth hormone (GH) is the key regulator of insulin-like growth factor I (IGF-I) generation in healthy states. However, portal insulin delivery is also an essential co-player in the regulation of the GH/IGF-I axis by affecting and regulating hepatic GH receptor synthesis, and subsequently altering hepatic GH sensitivity and IGF-I generation. Disease states of GH excess (e.g., acromegaly) and GH deficiency (e.g., congenital isolated GH deficiency) are characterized by increased and decreased GH, IGF-I and insulin levels, respectively, where the GH/IGF-I relationship is reflected by a "primary association". When intra-portal insulin levels are increased (e.g., obesity, Cushing's syndrome, or due to treatment with glucocorticoids and glucagon-like peptide 1 receptor agonists) or decreased (e.g., malnutrition, anorexia nervosa and type 1 diabetes mellitus), these changes secondarily alter hepatic GH sensitivity resulting in a "secondary association" with discordant GH and IGF-I levels (e.g., high GH/low IGF-I levels or low GH/high IGF-I levels, respectively). Additionally, intra-portal insulin regulates hepatic secretion of IGFBP-1, an inhibitor of IGF-I action. Through its effects on IGFBP-1 and subsequently free IGF-I, intra-portal insulin exerts its effects to influence endogenous GH secretion via the negative feedback loop. Therefore, it is important to understand the effects of changes in intra-portal insulin when interpreting the GH/IGF-I axis in disease states. This review summarizes our current understanding of how changes in intra-portal insulin delivery to the liver in health, disease states and drug therapy use and misuse that leads to alterations in GH/IGF-I secretion that may dictate management decisions in afflicted patients.

Case report: Pediatric hepatopulmonary syndrome despite strict weight control after craniopharyngioma surgery

Childhood-onset craniopharyngiomas, though rare, are intracranial malformations that can cause obesity by disrupting the hypothalamus, a condition that often persists even after tumor resection. This severe obesity increases the risk of diabetes and fatty liver disease in childhood. Concurrently, panhypopituitarism, including growth hormone (GH) deficiency, may develop. Notably, some individuals with GH deficiency may exhibit a normal growth rate, making GH therapy unnecessary for growth purposes. However, in these cases, GH therapy may still be beneficial in preventing the progression of nonalcoholic fatty liver disease or nonalcoholic steatohepatitis. Although weight management is traditionally considered the gold standard for preventing liver cirrhosis, its effectiveness can be limited by hypothalamic dysfunction and the difficulty of achieving successful weight control. Our case study highlights a patient with normal growth despite GH deficiency, who did not receive GH replacement therapy and continued to struggle with hypothalamic obesity. Despite effective body weight control, the patient developed hepatopulmonary syndrome, indicating that relying solely on weight management may not be sufficient to prevent liver complications. This case underscores the importance of addressing GH deficiency even when growth is normal. Our findings suggest that GH replacement therapy could be beneficial for preventing liver cirrhosis in such cases.

Nonlinear relationship between the triglyceride-glucose index and alanine aminotransferase in children with short stature

Metabolic dysfunction associated fatty liver disease (MAFLD) is a common cause of liver disease in children and adolescents. The relationship between insulin resistance (IR) and MAFLD in children with short stature remains largely unknown. The present study was to investigate the relationship between the triglyceride-glucose (TyG) index and alanine aminotransferase (ALT) levels in children with short stature. A total of 1754 children with short stature were enrolled. Anthropometric, biochemical and hormonal indexes were collected through physical measurement examinations and laboratory tests. A nonlinear association was found between the TyG index and ALT. The inflection point of the curve was at a TyG index of 8.24. In multivariate piecewise linear regression, only when the TyG index was greater than 8.24 was there a significant positive association between the TyG index and ALT (β 5.75, 95% CI 3.30, 8.19; P < 0.001). However, when the TyG index was less than 8.24, there was no significant association between the TyG index and ALT (β -0.57, 95% CI -1.84, 0.71; P = 0.382). This study demonstrated a nonlinear relationship between TyG index and ALT in children with short stature. This finding suggests that a high TyG index is associated with elevated ALT in children with short stature.

Effects of Metabolic Dysfunction-Associated Steatotic Liver Disease on Bone Density and Fragility Fractures: Associations and Mechanisms

Metabolic dysfunction-associated steatotic liver disease (MASLD) has profound adverse effects on bone health and homeostasis. MASLD appears to be associated with changes in bone mineral density (BMD) and fracture rate. However, the data are ambiguous and conflicting. Although several studies have shown that children and adolescents with MASLD have decreased BMD, the data on the prevalence of fragility fractures among children are scarce. In adults, increasing evidence suggests that MASLD decreases BMD and increases the risk of fragility fractures, which appears to be due to deterioration of bone architecture in addition to a decrease in BMD. Effects of MASLD on bone health may also be age- and race-specific. MASLD does not seem to increase fracture risk in children and adolescents but increases the risk of fractures in elderly men, especially those of Asian origin. From a mechanistic perspective, bone remodeling is a continuous process between osteoblasts (bone-forming) and osteoclasts (bone-resorbing), with any imbalance resulting in metabolic bone disease. In individuals with MASLD, loss of anabolic insulin receptor signaling (insulin resistance) in osteoblasts and increased receptor activator of nuclear factor κB (RANK)/RANK ligand signaling in osteoclasts (proinflammatory cytokines) swings the pendulum toward accelerated bone loss. These processes are further complicated by the concomitant presence of obesity, type 2 diabetes mellitus, or sarcopenia in individuals with MASLD. This study reviews the current literature associated with the effects of MASLD on BMD and fragility fractures in children/adolescents and adults. This review also discusses the pathomechanisms that link MASLD with changes in BMD and fragility fractures.

Development and basic performance verification of a rapid homogeneous bioassay for agonistic antibodies against the thyroid-stimulating hormone receptor

Graves' disease is a type of autoimmune hyperthyroidism caused by thyroid-stimulating antibodies (TSAb).1 The combination of a porcine thyroid cell bioassay and cyclic adenosine monophosphate (cAMP) immunoassay (TSAb-enzyme immunoassay; EIA) is a clinically approved TSAb measurement method. Due to the requirement of multiple procedures and a long assay time of 6 h in the TSAb-EIA, a simplified and rapid assay is desired. Herein, we developed a rapid homogeneous TSAb bioassay (rapid-TSAb assay) using the human embryonic kidney cell line (HEK293), engineered to express the human thyroid-stimulating hormone receptor (TSHR), along with a cAMP-dependent luminescence biosensor. The measurement consists of three steps: thawing frozen cells, blood sample addition, and luminescence detection. The procedures can be conducted within 1 h. The World Health Organization International Standard TSAb (NIBSC 08/204) stimulated the cells co-expressing TSHR and cAMP biosensor. The intra- and inter-assay coefficients of variance were < 10%. Stimulation activity using wild-type TSHR and chimeric TSHR (Mc4) almost completely correlated with the tested Graves' disease and normal samples. In the rapid-TSAb assay, the evaluation of 39 samples, including TSHR antibody-positive sera, yielded a sensitivity of 100.0% and a specificity of 90.9%, compared to the TSAb-EIA control. The rapid-TSAb assay enables simple and rapid measurement of TSAb and is promising for improving the diagnosis of autoimmune thyroid diseases.

Immune cell balance as potential biomarker of progressing non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a widespread chronic, slowly progressive metabolic multifactorial disease. It is represented by several clinical and morphological forms: steatosis, nonalcoholic steatohepatitis (NASH) (with or without fibrosis), and liver cirrhosis. The search for minimally invasive and cost-effective biomarkers of NAFLD is a key task in the diagnosis, staging of progression, and long-term monitoring of NAFLD. This article discusses the possibility of using immune cell balance as potential minimally invasive peripheral markers of NAFLD progression. In the progression of NASH from steatosis to fibrosis and cirrhosis, inflammation plays an important role because of the activation of Kupffer cells and increased migration of monocytes, dendritic cells, neutrophils, and activated T lymphocytes into the tissues. Macrophages originating from monocytes, with NASH progression, gradually begin to prevail over the pool of resident macrophages. The risk of NASH and fibrosis development in patients with NAFLD increases with the ratio of neutrophils/lymphocytes in the liver. An increase in the Th17 cell count and a decrease in T-regulatory cell count can contribute to increased hepatic steatosis and inflammation development in NAFLD and accelerate the transition from simple steatosis to steatohepatitis and fibrosis. Information on the participation of noncoding RNAs in the regulation of the balance of immune cells in NAFLD is presented, which also allows us to consider them as additional, along with cellular, markers of disease progression.

Nonalcoholic Fatty Liver Disease, Liver Fibrosis, and Utility of Noninvasive Scores in Patients With Acromegaly

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is a metabolical disorder and can lead to liver fibrosis. Because it is commonly seen, several noninvasive scores (NS) have been validated to identify high-risk patients. Patients with NAFLD have been shown to have higher serum angiopoietin-like protein-8 (ANGPTL-8) levels.

OBJECTIVE

The risk of NAFLD is known insufficiently in acromegaly. Moreover, the utility of the NS and the link between NAFLD and ANGPTL-8 in acromegaly is unknown.

METHODS

Thirty-two patients with acromegaly (n = 15, active [AA] and n = 17, controlled acromegaly [CA]) and 19 healthy controls were included. Magnetic resonance imaging (MRI)-proton density fat fraction (PDFF) was used to evaluate hepatic steatosis, and magnetic resonance elastography to evaluate liver stiffness measurement. ANGPTL-8 levels were measured with ELISA.

RESULTS

Median liver MRI-PDFF and NAFLD prevalence in AA were lower than in CA (P = .026 and P < .001, respectively). Median magnetic resonance elastography-liver stiffness measurement were similar across groups. Of the NS, visceral adiposity index, fatty liver index, hepatic steatosis index, and triglyceride-glucose index (TyG) all showed positive correlation with the liver MRI-PDFF in the control group. However, only TyG significantly correlated with liver fat in the AA and CA groups. There was no correlation between traditional NAFLD risk factors (body mass index, waist circumference, C-reactive protein, homeostasis model assessment for insulin resistance, visceral adipose tissue) and liver MRI-PDFF in the AA and CA. Patients with acromegaly with NAFLD had lower GH, IGF-1, and ANGPTL-8 levels than in those without NAFLD (P = .025, P = .011, and P = .036, respectively).

CONCLUSION

Active acromegaly may protect from NAFLD because of high GH. In patients with acromegaly, NAFLD risk cannot be explained with classical risk factors; hence, additional risk factors must be identified. TyG is the best score to evaluate NAFLD risk. Lower ANGPTL-8 in patients with acromegaly and NAFLD implies this hormone may be raised because of insulin resistance rather than being a cause for NAFLD.

Increased GH/IGF-I Axis Activity Relates to Lower Hepatic Lipids and Phosphor Metabolism

CONTEXT

Non-alcoholic fatty liver disease (NAFLD) is a leading causes of liver-related morbidity and mortality. While data on acromegaly, a state of chronic growth hormone (GH)/insulin-like growth factor I (IGF-I) excess, suggest an inverse relationship with intrahepatic lipid (IHL) content, less is known about the impact of the GH/IGF-I axis on IHL, lipid composition, and phosphor metabolites in individuals without disorders of GH secretion.

OBJECTIVE

The aim was to investigate the relation between activity of the GH/IGF-I axis and IHL content and phosphor metabolism.

METHODS

We performed a cross-sectional study in 59 otherwise metabolically healthy individuals (30 females), of which 16 met the criteria of NAFLD with IHL of ≥5.6%. The GH/IGF-I axis was evaluated in a fasting state and during an oral glucose tolerance test (OGTT). Insulin sensitivity was estimated by validated indices. IHL, lipid composition (unsaturation index), and phosphate metabolites were analyzed by using 1H/31P magnetic resonance spectroscopy.

RESULTS

In the overall cohort (40.6 ± 15 years; body mass index: 24.5 ± 3 kg/m2; IGF-I: 68.0 ± 17% upper limit of normal), fasting GH (R = -0.31; P = .02), GH during oral glucose tolerance test (R = -0.51; P < .01), and IGF-I (R = -0.28; P = .03) inversely correlated with IHL. GH levels during OGTT were significantly lower in NAFLD than in controls (47.7 [22; 143] ng/mL/min vs 16.8 [7; 32] ng/mL/min; P = .003). GH/IGF-I axis activity correlated with lipid composition and with phosphor metabolites. In multiple regression analysis, the GH/IGF-I axis activity was a strong predictor for IHL and lipid composition independent from insulin sensitivity.

CONCLUSION

GH/IGF-I axis activity impacts hepatic lipid and phosphate metabolism in individuals without disorders in GH secretion. Lower GH axis activity is associated with higher IHL and an unfavorable lipid composition, probably mediated by changes in hepatic energy metabolism.

Growth Hormone Signaling in Liver Diseases: Therapeutic Potentials and Controversies

Growth hormone (GH) and downstream insulin-like growth factor 1 (IGF1) signaling mediate growth and metabolism. GH deficiency causes short stature or dwarfism, and excess GH causes acromegaly. Although the association of GH/IGF1 signaling with liver diseases has been suggested previously, current studies are controversial and the functional roles of GH/IGF1 signaling are still undefined. GH supplementation therapy showed promising therapeutic effects in some patients, such as non-alcoholic fatty liver disease, but inhibition of GH signaling may be beneficial for other liver diseases, such as hepatocellular carcinoma. The functional roles of GH/IGF1 signaling and the effects of agonists/antagonists targeting this signaling may differ depending on the liver injury or animal models. This review summarizes current controversial studies of GH/IGF1 signaling in liver diseases and discusses therapeutic potentials of GH therapy.

Non-alcoholic fatty liver disease across endocrinopathies: Interaction with sex hormones

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most frequent chronic liver disease globally. NAFLD is strongly associated with metabolic syndrome and it has been recently suggested that to rename NAFLD as metabolic dysfunction-associated fatty liver disease (MAFLD). NAFLD has been studied in different endocrine axes and accumulating body of clinical and experimental studies have suggested that NAFLD is associated with polycystic ovarian syndrome (PCOS), hypopituitarism, growth hormone deficiency (GHD), hypogonadism and other endocrine disorders. In fact, endocrine dysfunction may be considered as the major contributor for the development, progression, and severity of NAFLD. In the present comprehensive review, we discussed the epidemiological and clinical evidence on the epidemiology, pathophysiology, and management of NAFLD in endocrine disorders, with an emphasis on the effects of sex-specific hormones/conditions as well as molecular basis of NAFLD development in these endocrine diseases.

Important Hormones Regulating Lipid Metabolism

There is a wide variety of kinds of lipids, and complex structures which determine the diversity and complexity of their functions. With the basic characteristic of water insolubility, lipid molecules are independent of the genetic information composed by genes to proteins, which determine the particularity of lipids in the human body, with water as the basic environment and genes to proteins as the genetic system. In this review, we have summarized the current landscape on hormone regulation of lipid metabolism. After the well-studied PI3K-AKT pathway, insulin affects fat synthesis by controlling the activity and production of various transcription factors. New mechanisms of thyroid hormone regulation are discussed, receptor α and β may mediate different procedures, the effect of thyroid hormone on mitochondria provides a new insight for hormones regulating lipid metabolism. Physiological concentration of adrenaline induces the expression of extrapituitary prolactin in adipose tissue macrophages, which promotes fat weight loss. Manipulation of hormonal action has the potential to offer a new therapeutic horizon for the global burden of obesity and its associated complications such as morbidity and mortality.

Long-term outcomes in patients with adult-onset craniopharyngioma

PURPOSE

Craniopharyngiomas are nonmalignant sellar and parasellar tumors exhibiting a bimodal age distribution. While the outcomes following treatment in patients with childhood-onset craniopharyngiomas are well characterized, similar information in adult-onset craniopharyngiomas is limited. We aimed to describe the long-term outcomes (weight and metabolic parameters, mortality) in patients with adult-onset craniopharyngioma following treatment.

METHODS

Patients with adult-onset craniopharyngioma with initial treatment (1993-2017) and >6 months of follow-up at our institution were retrospectively identified. Body mass index (BMI) categories included obese (BMI ≥ 30 kg/m2), overweight (BMI 25-29.9 kg/m2), and normal weight (BMI < 25 kg/m2).

RESULTS

For the 91 patients with adult-onset craniopharyngioma (44% women, mean diagnosis age 48.2 ± 18 years) over a mean follow-up of 100.3 ± 69.5 months, weight at last follow-up was significantly higher than before surgery (mean difference 9.5 ± 14.8 kg, P < 0.001) with a higher percentage increase in weight seen in those with lower preoperative BMI (normal weight (20.7 ± 18%) vs. overweight (13.3 ± 18.0%) vs. obese (6.4 ± 15%), P = 0.012). At last follow-up, the prevalence of obesity (62 vs. 40.5%, P = 0.0042) and impaired glucose metabolism (17.4% vs. 34%, P = 0.017) increased significantly. All-cause mortality was 12%, with the average age of death 71.9 ± 19.7 years (average U.S. life expectancy 77.7 years, CDC 2020).

CONCLUSION

Patients with adult-onset craniopharyngioma following treatment may experience weight gain, increased prevalence of obesity, impaired glucose metabolism, and early mortality. Lower preoperative BMI is associated with a greater percentage increase in postoperative weight.

The GH/IGF-1 Axis Is Associated With Intrahepatic Lipid Content and Hepatocellular Damage in Overweight/Obesity

CONTEXT

Obesity is a state of relative growth hormone (GH) deficiency, and GH has been identified as a candidate disease-modifying target in nonalcoholic fatty liver disease (NAFLD) because of its lipolytic and anti-inflammatory properties. However, the GH/IGF-1 axis has not been well characterized in NAFLD.

OBJECTIVE

We aimed to investigate serum GH and IGF-1 levels in relation to intrahepatic lipid content (IHL) and markers of hepatocellular damage and fibrosis in NAFLD.

METHODS

This cross-sectional study included 102 adults (43% women; age 19-67; BMI ≥ 25 kg/m2) without type 2 diabetes. IHL was measured by magnetic resonance spectroscopy; NAFLD was defined by ≥ 5% IHL. Peak-stimulated GH in response to GH releasing hormone and arginine was assessed as was serum IGF-1 (LC/MS).

RESULTS

There was no difference in mean age, BMI, or sex distribution in NAFLD vs controls. Mean (± SD) IHL was higher in NAFLD vs controls (21.8 ± 13.3% vs 2.9 ± 1.1%, P < 0.0001). Mean peak-stimulated GH was lower in NAFLD vs controls (9.0 ± 6.3 vs 15.4 ± 11.2 ng/mL, P = 0.003), including after controlling for age, sex, visceral adipose tissue, and fasting glucose. In a stepwise model, peak-stimulated GH predicted 14.6% of the variability in IHL (P = 0.004). Higher peak-stimulated GH was also associated with lower ALT. Higher serum IGF-1 levels were associated with lower risk of liver fibrosis by Fibrosis-4 scores.

CONCLUSION

Individuals with NAFLD have lower peak-stimulated GH levels but similar IGF-1 levels as compared to controls. Higher peak-stimulated GH levels are associated with lower IHL and less hepatocellular damage. Higher IGF-1 levels are associated with more favorable fibrosis risk scores. These data implicate GH and IGF-1 as potential disease modifiers in the development and progression of NAFLD.

Growth hormone deficiency and NAFLD: An overlooked and underrecognized link

Growth hormone and its mediator insulin‐like growth factor‐1 exert their effect on different organs and control various physiologic metabolic processes. Adult growth hormone deficiency (AGHD) presents with one or more components of metabolic syndrome and can be associated with nonalcoholic fatty liver disease (NAFLD). AGHD is present in spectrum of hypothalamic/pituitary disorders as well as cranial radiation of brain tumors and often remains underdiagnosed or untreated due to its nonspecific symptoms, relatively difficult diagnosis in some clinical scenarios, and various barriers to treatment. NAFLD usually develops soon after diagnosis of AGHD and might progress rapidly to nonalcoholic steatohepatitis (NASH) with advanced fibrosis, eventually requiring liver transplantation. A timely initiation of growth hormone replacement therapy might be important, although studies so far have demonstrated controversial results on NAFLD, primarily due to small sample size and different diagnostic methods of NAFLD. Increased awareness of the association between AGHD and NAFLD would facilitate early diagnosis of NAFLD and NASH if present. Therefore, a multidisciplinary approach involving hepatology and endocrinology should become a standard of care for these patients.

Growth Hormone and Insulin-Like Growth Factor 1 Regulation of Nonalcoholic Fatty Liver Disease

Patients with obesity have a high prevalence of nonalcoholic fatty liver disease (NAFLD), representing a spectrum of simple steatosis to nonalcoholic steatohepatitis (NASH), without and with fibrosis. Understanding the etiology of NAFLD is clinically relevant since NAFLD is an independent risk factor for diabetes and cardiovascular disease. In addition, NASH predisposes patients to the development of cirrhosis and hepatocellular carcinoma, and NASH cirrhosis represents the fastest growing indication for liver transplantation in the United States. It is appreciated that multiple factors are involved in the development and progression of NAFLD. Growth hormone (GH) and insulin-like growth factor 1 (IGF1) regulate metabolic, immune, and hepatic stellate cell function, and alterations in the production and function of GH is associated with obesity and NAFLD/NASH. Therefore, this review will focus on the potential role of GH and IGF1 in the regulation of hepatic steatosis, inflammation, and fibrosis.

Towards Understanding the Direct and Indirect Actions of Growth Hormone in Controlling Hepatocyte Carbohydrate and Lipid Metabolism

Growth hormone (GH) is critical for achieving normal structural growth. In addition, GH plays an important role in regulating metabolic function. GH acts through its GH receptor (GHR) to modulate the production and function of insulin-like growth factor 1 (IGF1) and insulin. GH, IGF1, and insulin act on multiple tissues to coordinate metabolic control in a context-specific manner. This review will specifically focus on our current understanding of the direct and indirect actions of GH to control liver (hepatocyte) carbohydrate and lipid metabolism in the context of normal fasting (sleep) and feeding (wake) cycles and in response to prolonged nutrient deprivation and excess. Caveats and challenges related to the model systems used and areas that require further investigation towards a clearer understanding of the role GH plays in metabolic health and disease are discussed.

High Prevalence of Nonalcoholic Fatty Liver Disease Among Adolescents and Young Adults With Hypopituitarism due to Growth Hormone Deficiency

OBJECTIVE

To investigate the prevalence of nonalcoholic fatty liver disease (NAFLD) in adolescents and young adults with hypopituitarism and to examine the associations of growth hormone (GH) deficiency with the occurrence of NAFLD.

METHODS

A cross-sectional study for the determination of NAFLD prevalence included 76 patients with childhood-onset hypopituitarism and 74 controls matched by age and body mass index (BMI). We investigated the prevalence of NAFLD in adolescent and young adult patients with hypopituitarism as well as the age- and BMI-matched controls. Among patients with hypopituitarism, anthropometric, clinical, and biochemical assessments using transient elastography and magnetic resonance imaging were performed. Logistic regression was used to identify the factors associated with NAFLD.

RESULTS

The adolescents and young adults with hypopituitarism exhibited higher prevalence of NAFLD than the age- and BMI-matched controls. Among patients with hypopituitarism, obesity and obesity-related metabolic derangements were significantly associated with liver steatosis and fibrosis, whereas lower insulin-like growth factor (IGF)-I standard deviation score (SDS) and IGF-I/IGF-binding protein 3 molar ratios were associated with steatosis. In regression analyses adjusted for BMI SDS, steatosis was found to be associated with a lower IGF-I SDS and IGF-I/IGF-binding protein 3 molar ratios, whereas liver fibrosis was found to be associated with a lower IGF-I SDS.

CONCLUSION

Our results suggest that GH deficiency contributes to the occurrence of NAFLD, along with obesity and obesity-related metabolic changes. Because NAFLD occurs early in patients with hypopituitarism, the surveillance, weight control, and timely replacement of deficit hormones, including GH, are essential.

GH directly inhibits steatosis and liver injury in a sex-dependent and IGF1-independent manner

A reduction in hepatocyte growth hormone (GH)-signaling promotes non-alcoholic fatty liver disease (NAFLD). However, debate remains as to the relative contribution of the direct effects of GH on hepatocyte function vs indirect effects, via alterations in insulin-like growth factor 1 (IGF1). To isolate the role of hepatocyte GH receptor (GHR) signaling, independent of changes in IGF1, mice with adult-onset, hepatocyte-specific GHR knockdown (aHepGHRkd) were treated with a vector expressing rat IGF1 targeted specifically to hepatocytes. Compared to GHR-intact mice, aHepGHRkd reduced circulating IGF1 and elevated GH. In male aHepGHRkd, the shift in IGF1/GH did not alter plasma glucose or non-esterified fatty acids (NEFA), but was associated with increased insulin, enhanced systemic lipid oxidation and reduced white adipose tissue (WAT) mass. Livers of male aHepGHRkd exhibited steatosis associated with increased de novo lipogenesis, hepatocyte ballooning and inflammation. In female aHepGHRkd, hepatic GHR protein levels were not detectable, but moderate levels of IGF1 were maintained, with minimal alterations in systemic metabolism and no evidence of steatosis. Reconstitution of hepatocyte IGF1 in male aHepGHRkd lowered GH and normalized insulin, whole body lipid utilization and WAT mass. However, IGF1 reconstitution did not reduce steatosis or eliminate liver injury. RNAseq analysis showed IGF1 reconstitution did not impact aHepGHRkd-induced changes in liver gene expression, despite changes in systemic metabolism. These results demonstrate the impact of aHepGHRkd is sexually dimorphic and the steatosis and liver injury observed in male aHepGHRkd mice is autonomous of IGF1, suggesting GH acts directly on the adult hepatocyte to control NAFLD progression.

Pituitary stalk interruption syndrome and liver changes: From clinical features to mechanisms

Pituitary stalk interruption syndrome (PSIS) is a rare congenital abnormality characterized by thinning or disappearance of the pituitary stalk, hypoplasia of the anterior pituitary and an ectopic posterior pituitary. Although the etiology of PSIS is still unclear, gene changes and perinatal adverse events such as breech delivery may play important roles in the pathogenesis of PSIS. PSIS can cause multiple hormone deficiencies, such as growth hormone, which then cause a series of changes in the human body. On the one hand, hormone changes affect growth and development, and on the other hand, they could affect human metabolism and subsequently the liver resulting in nonalcoholic fatty liver disease (NAFLD). Under the synergistic effect of multiple mechanisms, the progression of NAFLD caused by PSIS is faster than that due to other causes. Therefore, in addition to early identification of PSIS, timely hormone replacement therapy and monitoring of relevant hormone levels, clinicians should routinely assess the liver function while managing PSIS.

Height predict incident non-alcoholic fatty liver disease among general adult population in Tianjin, China, independent of body mass index, waist circumference, waist-to-height ratio, and metabolic syndrome

Background

Early-life hormonal and nutritional factors can greatly influence the risk of non-alcoholic fatty liver disease (NAFLD). Adult height is a simple marker for these factors. This study aimed to investigate the association between adult height and NAFLD.

Methods

We performed a prospective cohort study of 35,994 participants aged 25 years or over with measured height at baseline. NAFLD was diagnosed by abdominal ultrasound and self-reported history of alcohol intake. Multivariable Cox proportional hazards regression models were conducted to assess the gender-specific association between height and the risk of NAFLD.

Results

During a follow-up period of 5.5 years, 6245 of 35,994 subjects developed NAFLD. The adjusted hazard ratios (95% confidence interval) of NAFLD for increasing quintiles of height were 1.00 (reference), 0.82 (0.73, 0.92), 0.84 (0.73, 0.97), 0.72 (0.61, 0.85) and 0.63 (0.50, 0.79) (P for trend < 0.0001) in males, and 1.00 (reference), 1.00 (reference), 0.80 (0.69, 0.91), 0.72 (0.61, 0.85), 0.60 (0.49, 0.74) and 0.45 (0.35, 0.59) (P for trend < 0.0001) in females, respectively.

Conclusions

A higher adult height was associated with lower risk of NAFLD among males and females in Tianjin, China.

Hepatic steatosis in patients with acromegaly

OBJECTIVE

Comorbid NAFLD is increasingly being diagnosed in patients with diabetes and nondiabetic endocrinopathies. The aim of this study was to assess hepatic steatosis noninvasively by transient elastography in patients with acromegaly.

DESIGN

A cross-sectional study including 22 patients with acromegaly.

METHODS

Hepatic steatosis was quantified using controlled attenuation parameter (CAP) during elastography. Anthropometric measurements were obtained, serum liver function tests and lipid and hormone profiles were measured, and prosteatogenic gene variants were genotyped using standard assays.

RESULTS

In total, 41% of patients were women (mean age 60 ± 14.7 years, mean BMI 31.2 ± 4.6 kg/m2). Hepatic steatosis, as defined by CAP > 248 dB/m, was present in 66% of patients. Five (45%) of the patients with hepatic steatosis also had fibrosis, and one presented with cirrhosis. Nine patients were carriers of the PNPLA3 p.I148M prosteatogenic [M] risk allele, eight of whom were heterozygotes. CAP values were significantly (P = .045) higher in these patients and corresponded to advanced steatosis, as compared to patients with the wild-type genotype, who demonstrated CAP values consistent with mild steatosis (311 ± 33 dB/m. vs 254 ± 62 dB/m). CAP values did not differ significantly in carriers of distinct TM6SF2 and MBOAT7 genotypes; however, carriers of the risk alleles displayed higher CAP as compared to wild-type patients.

CONCLUSIONS

This study shows that in patients with acromegaly, carriers of the PNPLA3 susceptibility allele are at risk of developing hepatic steatosis, as assessed by CAP. Comorbid NAFLD might compound prognosis in such patients; thus, further research into the pathomechanisms and treatment of NAFLD in acromegaly is warranted.

Extrahepatic complications of non-alcoholic fatty liver disease: Its impact beyond the liver

Non-alcoholic fatty liver disease (NAFLD) is currently one of the main causes of chronic liver disease in Western countries, with a 25% prevalence reported in the general population worldwide. Visceral adiposity and liver fat promote a state of systemic inflammation, predisposing individuals with NAFLD to the extrahepatic pathologies of cardiovascular disease (the most common cause of death in patients with NAFLD), diabetes mellitus, chronic kidney disease, hypothyroidism, polycystic ovary syndrome, obstructive sleep apnea, and an increased risk for presenting with gastrointestinal and extraintestinal neoplasias. Different mechanisms between NAFLD and its association with extrahepatic diseases have been reported, and lipotoxicity is the main cause of inflammatory pathway activation that results in extrahepatic tissue damage.

Loss of Adipose Growth Hormone Receptor in Mice Enhances Local Fatty Acid Trapping and Impairs Brown Adipose Tissue Thermogenesis

Growth hormone (GH) binds to its receptor (growth hormone receptor [GHR]) to exert its pleiotropic effects on growth and metabolism. Disrupted GH/GHR actions not only fail growth but also are involved in many metabolic disorders, as shown in murine models with global or tissue-specific Ghr deficiency and clinical observations. Here we constructed an adipose-specific Ghr knockout mouse model Ad-GHRKO and studied the metabolic adaptability of the mice when stressed by high-fat diet (HFD) or cold. We found that disruption of adipose Ghr accelerated dietary obesity but protected the liver from ectopic adiposity through free fatty acid trapping. The heat-producing brown adipose tissue burning and white adipose tissue browning induced by cold were slowed in the absence of adipose Ghr but were recovered after prolonged cold acclimation. We conclude that at the expense of excessive subcutaneous fat accumulation and lower emergent cold tolerance, down-tuning adipose GHR signaling emulates a healthy obesity situation which has metabolic advantages against HFD.

NAFLD in Some Common Endocrine Diseases: Prevalence, Pathophysiology, and Principles of Diagnosis and Management

Secondary nonalcoholic fatty liver disease (NAFLD) defines those complex pathophysiological and clinical consequences that ensue when the liver becomes an ectopic site of lipid storage owing to reasons other than its mutual association with the metabolic syndrome. Disorders affecting gonadal hormones, thyroid hormones, or growth hormones (GH) may cause secondary forms of NAFLD, which exhibit specific pathophysiologic features and, in theory, the possibility to receive an effective treatment. Here, we critically discuss epidemiological and pathophysiological features, as well as principles of diagnosis and management of some common endocrine diseases, such as polycystic ovary syndrome (PCOS), hypothyroidism, hypogonadism, and GH deficiency. Collectively, these forms of NAFLD secondary to specific endocrine derangements may be envisaged as a naturally occurring disease model of NAFLD in humans. Improved understanding of such endocrine secondary forms of NAFLD promises to disclose novel clinical associations and innovative therapeutic approaches, which may potentially be applied also to selected cases of primary NAFLD.

CircScd1 Promotes Fatty Liver Disease via the Janus Kinase 2/Signal Transducer and Activator of Transcription 5 Pathway

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in affluent countries. Recent studies have reported that circular RNAs (circRNAs) are important regulators of hepatic steatosis. However, the role and mechanism of circRNA in NAFLD are poorly understood.

AIMS

This study is to reveal the role and mechanism of circRNA in NAFLD.

METHODS

Through NAFLD-related circRNA microarrays, we used real-time quantitative reverse transcription-polymerase chain reaction to screen circScd1 levels in control and test groups of mice fed a high-fat diet. RNA interference and over-expression plasmid vectors were used to manipulate the expression of circScd1, and the biological effects were evaluated by oil red staining, triglyceride detection, and western blot analysis.

RESULTS

CircScd1 expression was significantly lower in NAFLD tissues than in control tissues. Moreover, over-expression of circScd1 significantly inhibited the formation of lipid droplets. Western blot analyses showed that the protein levels of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 5 (STAT5) were significantly increased. However, knockdown of circScd1 significantly promoted the degree of hepatocellular lipidosis and reduced the expression levels of JAK2 and STAT5.

CONCLUSIONS

Aberrant expression of circScd1 affects the extent of hepatocellular lipidosis in NAFLD and promotes fatty liver disease via the JAK2/STAT5 pathway.

Adult-Onset Hepatocyte GH Resistance Promotes NASH in Male Mice, Without Severe Systemic Metabolic Dysfunction

Nonalcoholic fatty liver disease (NAFLD), which includes nonalcoholic steatohepatitis (NASH), is associated with reduced GH input/signaling, and GH therapy is effective in the reduction/resolution of NAFLD/NASH in selected patient populations. Our laboratory has focused on isolating the direct vs indirect effects of GH in preventing NAFLD/NASH. We reported that chow-fed, adult-onset, hepatocyte-specific, GH receptor knockdown (aHepGHRkd) mice rapidly (within 7 days) develop steatosis associated with increased hepatic de novo lipogenesis (DNL), independent of changes in systemic metabolic function. In this study, we report that 6 months after induction of aHepGHRkd early signs of NASH develop, which include hepatocyte ballooning, inflammation, signs of mild fibrosis, and elevated plasma alanine aminotransferase. These changes occur in the presence of enhanced systemic lipid utilization, without evidence of white adipose tissue lipolysis, indicating that the liver injury that develops after aHepGHRkd is due to hepatocyte-specific loss of GH signaling and not due to secondary defects in systemic metabolic function. Specifically, enhanced hepatic DNL is sustained with age in aHepGHRkd mice, associated with increased hepatic markers of lipid uptake/re-esterification. Because hepatic DNL is a hallmark of NAFLD/NASH, these studies suggest that enhancing hepatocyte GH signaling could represent an effective therapeutic target to reduce DNL and treat NASH.

Growth Hormone Deficiency and Nonalcoholic Fatty Liver Disease with Insights from Humans and Animals: Pediatric Implications

In addition to its growth promoting role, growth hormone (GH) has a significant effect on intermediary metabolism in the well state. Despite the latter fact, pediatric practitioners are usually focused on the growth promoting aspects of GH as opposed to those metabolic. In recent years various animal and human studies (in adults mainly) and clinical reports in children have repeatedly shown the association of GH deficiency (GHD) and fatty liver disease. Based on this well-identified association, despite a lack of studies involving children, it behooves the pediatric clinician to ensure that not only patients with GHD are appropriately treated but also that adolescents even beyond the period of linear growth should be appropriately transitioned to adult GH therapy should this be appropriate.

Metabolic effects of reduced growth hormone action in fatty liver disease

Background

Adult growth hormone (GH) deficiency is associated with fatty liver disease and shows several features of the metabolic syndrome. Vice versa obesity is characterized as a state of low GH function. Here, we aimed to define the role of hepatic GH signaling and its metabolic consequences in non-alcoholic fatty liver disease.

Methods

In humans, GHR and IGF-1 levels were determined in liver samples of 29 obese patients with non-alcoholic steatohepatitis (NASH) or simple steatosis. Cellular effects of GH on insulin signaling were investigated in GH receptor (GHR) knockdown HepG2 cells.

Results

Hepatic IGF-1 expression levels reflecting GH action were significantly lower and fasting glucose concentrations higher in patients with NASH than in patients with simple steatosis. GHR knockdown in hepatocytes resulted in a scenario of high glucose output displayed by reduced glycogen content, increased gluconeogenesis and diminished insulin signaling.

Conclusions

Our data suggest that GH signaling in the liver is diminished in patients with NASH and associated with deteriorated hepatic insulin sensitivity and metabolic activity. Reduced hepatic GH action might contribute to insulin resistance in obese patients with NASH.

The Growth Hormone Receptor: Mechanism of Receptor Activation, Cell Signaling, and Physiological Aspects

The growth hormone receptor (GHR), although most well known for regulating growth, has many other important biological functions including regulating metabolism and controlling physiological processes related to the hepatobiliary, cardiovascular, renal, gastrointestinal, and reproductive systems. In addition, growth hormone signaling is an important regulator of aging and plays a significant role in cancer development. Growth hormone activates the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway, and recent studies have provided a new understanding of the mechanism of JAK2 activation by growth hormone binding to its receptor. JAK2 activation is required for growth hormone-mediated activation of STAT1, STAT3, and STAT5, and the negative regulation of JAK-STAT signaling comprises an important step in the control of this signaling pathway. The GHR also activates the Src family kinase signaling pathway independent of JAK2. This review covers the molecular mechanisms of GHR activation and signal transduction as well as the physiological consequences of growth hormone signaling.

Hepatic lipid metabolism and non-alcoholic fatty liver disease in aging

Aging is associated with dysregulation of glucose and lipid metabolism. Various factors that contribute to the dysregulation include both modifiable (e.g. obesity, insulin resistance) and non-modifiable risk factors (age-associated physiologic changes). Although there is no linear relationship between aging and prevalence of non-alcoholic fatty liver disease, current data strongly suggests that advanced age leads to more severe histological changes and poorer clinical outcomes. Hepatic lipid accumulation could lead to significant hepatic and systemic consequences including steatohepatitis, cirrhosis, impairment of systemic glucose metabolism and metabolic syndrome, thereby contributing to age-related diseases. Insulin, leptin and adiponectin are key regulators of the various physiologic processes that regulate hepatic lipid metabolism. Recent advances have expanded our understanding in this field, highlighting the role of novel mediators such as FGF 21, and mitochondria derived peptides. In this review, we will summarize the mediators of hepatic lipid metabolism and how they are altered in aging.

Hepatic lipid accumulation: cause and consequence of dysregulated glucoregulatory hormones

Fatty liver can be diet, endocrine, drug, virus or genetically induced. Independent of cause, hepatic lipid accumulation promotes systemic metabolic dysfunction. By acting as peroxisome proliferator-activated receptor (PPAR) ligands, hepatic non-esterified fatty acids upregulate expression of gluconeogenic, beta-oxidative, lipogenic and ketogenic genes, promoting hyperglycemia, hyperlipidemia and ketosis. The typical hormonal environment in fatty liver disease consists of hyperinsulinemia, hyperglucagonemia, hypercortisolemia, growth hormone deficiency and elevated sympathetic tone. These endocrine and metabolic changes further encourage hepatic steatosis by regulating adipose tissue lipolysis, liver lipid uptake, de novo lipogenesis (DNL), beta-oxidation, ketogenesis and lipid export. Hepatic lipid accumulation may be induced by 4 separate mechanisms: (1) increased hepatic uptake of circulating fatty acids, (2) increased hepatic de novo fatty acid synthesis, (3) decreased hepatic beta-oxidation and (4) decreased hepatic lipid export. This review will discuss the hormonal regulation of each mechanism comparing multiple physiological models of hepatic lipid accumulation. Nonalcoholic fatty liver disease (NAFLD) is typified by increased hepatic lipid uptake, synthesis, oxidation and export. Chronic hepatic lipid signaling through PPARgamma results in gene expression changes that allow concurrent activity of DNL and beta-oxidation. The importance of hepatic steatosis in driving systemic metabolic dysfunction is highlighted by the common endocrine and metabolic disturbances across many conditions that result in fatty liver. Understanding the mechanisms underlying the metabolic dysfunction that develops as a consequence of hepatic lipid accumulation is critical to identifying points of intervention in this increasingly prevalent disease state.

Insulin-like growth factor 1 and metabolic parameters are associated with nonalcoholic fatty liver disease in obese children and adolescents

AIM

Few studies have investigated the relationship between paediatric nonalcoholic fatty liver disease (NAFLD) and insulin-like growth factor 1 (IGF-1). This study, carried out from July 2013 to September 2015, aimed to fill the gap and added metabolic parameters to the analysis.

METHODS

This was a cross-sectional study of 168 obese children and adolescents (84% male), divided into two groups based on the presence (n = 90) or absence (n = 78) of NAFLD. All participants underwent clinical examinations, anthropometric and laboratory examinations and liver ultrasonography.

RESULTS

Nonalcoholic fatty liver disease patients had significantly lower IGF-1 standard deviation score (IGF-1 SDS) and higher body mass index (BMI), homeostasis model assessment of insulin resistance (HOMA-IR) and uric acid levels than the control group. The prevalence rate of NAFLD was negatively correlated with the IGF-1 SDS. IGF-1 SDS was negatively associated with NAFLD, while BMI, HOMA-IR and uric acid were positively associated with NAFLD. The combined analysis of the area under the receiver operating characteristic curve for multiple variables, including IGF-1 SDS, BMI, HOMA-IR and uric acid, was 0.812, with a sensitivity of 78.89% and specificity of 74.36%.

CONCLUSION

IGF-1, BMI, HOMA-IR and uric acid were useful markers of NAFLD in obese children and adolescents.

The Association Between IGF-1 Levels and the Histologic Severity of Nonalcoholic Fatty Liver Disease

Objectives:

The mechanisms responsible for the development of nonalcoholic fatty liver disease (NAFLD) and progression to nonalcoholic steatohepatitis (NASH) are incompletely understood. Growing evidence suggests that growth hormone (GH) and insulin-like growth factor-1 (IGF-1) may have roles in the development and progression of NAFLD. We hypothesized that lower serum IGF-1 levels would be associated with increased liver fat accumulation, inflammation, and fibrosis in a group of meticulously phenotyped obese subjects with liver biopsies.

Methods:

A retrospective, cross-sectional study was performed at Massachusetts General Hospital, Boston, MA, USA and St. Mary's Hospital, Richmond, VA, USA. Liver biopsies were performed in 142 subjects during NAFLD work-up or bariatric surgery and were graded by a single, blinded pathologist. Main outcome measures included liver histology and serum IGF-1.

Results:

Mean age was 52±10 years and body mass index (BMI) was 43±9 kg/m². Mean serum IGF-1 was lower in subjects with lobular inflammation (112±47 vs. 136±57 ng/ml, P=0.01), hepatocyte ballooning (115±48 vs. 135±57 ng/ml, P=0.05), higher fibrosis stage (stage 2–4 vs. 0–1; 96±40 vs. 125±51 ng/ml, P=0.005), and NASH (109±45 vs. 136±57 ng/ml, P=0.002). All results remained significant after controlling for age, BMI, and a diagnosis of diabetes, and all but hepatocyte ballooning (trend, P=0.06) remained significant after excluding individuals with cirrhosis. Steatosis was not significantly associated with mean serum IGF-1 levels.

Conclusions:

Low serum IGF-1 levels are associated with increased histologic severity of NAFLD when rigorously controlled for age, BMI, the presence of diabetes, and after the exclusion of subjects with cirrhosis. Further investigation is warranted to determine the differential effects of GH and IGF-1 on the development and progression of NAFLD, which could further elucidate pathophysiology and identify therapeutic targets.

The Relationship between the Growth Hormone/Insulin-like Growth Factor System and the Histological Features of Nonalcoholic Fatty Liver Disease

Objective Growth hormone (GH) deficiency has recently been reported as a cause of nonalcoholic fatty liver disease (NAFLD), and GH supplementation has been shown to improve the histology of NAFLD. The aim of the present study was to clarify the relationship between the histological severity of NAFLD and production of the GH/insulin-like growth factor 1 (IGF-1) axis. Methods A total of 222 Japanese patients with liver biopsy-confirmed NAFLD and 55 patients with hepatitis C virus (HCV)-related chronic liver disease (CLD) were enrolled in the present study. The serum levels of GH, IGF-1, and IGF-binding protein 3 (IGFBP-3) were measured and their relationships with the histological severity of liver disease were assessed. To exclude age- and sex-related differences, the IGF-1 standard deviation score (IGF-1:SDS) was determined for each patient. Results With respect to the stage of fibrosis in patients with NAFLD, the serum GH levels were higher and the serum IGFBP-3 levels and IGF-1:SDSs were lower in patients with cirrhosis (grade F4 fibrosis) than in patients grade F1-F3 fibrosis; moreover, these differences were statistically significant (all p<0.01). The GH, IGF-1, and IGFBP-3 levels were not correlated with fibrosis in patients with HCV-related CLD. Furthermore, the GH levels were lower and the IGFBP-3 levels were significantly higher in patients with severe steatosis (S3) than in patients with mild to moderate steatosis (S1-S2) (p<0.05). Conclusion Increased GH levels and decreased IGF-1 and IGFBP-3 levels might contribute to the progression of NAFLD. The GH/IGF-1 axis may be important in the development of NAFLD, but not in patients with HCV-related CLD.

Growth Hormone Control of Hepatic Lipid Metabolism

In humans, low levels of growth hormone (GH) and its mediator, IGF-1, associate with hepatic lipid accumulation. In mice, congenital liver-specific ablation of the GH receptor (GHR) results in reductions in circulating IGF-1 and hepatic steatosis, associated with systemic insulin resistance. Due to the intricate relationship between GH and IGF-1, the relative contribution of each hormone to the development of hepatic steatosis is unclear. Our goal was to dissect the mechanisms by which hepatic GH resistance leads to steatosis and overall insulin resistance, independent of IGF-1. We have generated a combined mouse model with liver-specific ablation of GHR in which we restored liver IGF-1 expression via the hepatic IGF-1 transgene. We found that liver GHR ablation leads to increases in lipid uptake, de novo lipogenesis, hyperinsulinemia, and hyperglycemia accompanied with severe insulin resistance and increased body adiposity and serum lipids. Restoration of IGF-1 improved overall insulin sensitivity and lipid profile in serum and reduced body adiposity, but was insufficient to protect against steatosis-induced hepatic inflammation or oxidative stress. We conclude that the impaired metabolism in states of GH resistance results from direct actions of GH on lipid uptake and de novo lipogenesis, whereas its actions on extrahepatic tissues are mediated by IGF-1.

Extrahepatic Complications of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is an important cause of liver disease that is often associated with the metabolic syndrome. There is a growing awareness that extrahepatic complications occur in individuals with NAFLD, especially an increased risk of cardiovascular disease. Development of diabetes mellitus, chronic kidney disease, colorectal cancer, and endocrinopathies has been linked to NAFLD. This article reviews the extrahepatic complications affecting individuals with NAFLD and the pathogenesis underlying their development.

Hepatic PPARγ Is Not Essential for the Rapid Development of Steatosis After Loss of Hepatic GH Signaling, in Adult Male Mice

Our group has previously reported de novo lipogenesis (DNL) and hepatic triglyceride content increases in chow-fed male mice within 7 days of hepatocyte-specific GH receptor knockdown (aLivGHRkd). Here, we report that these changes are associated with an increase in hepatic expression of peroxisome proliferator-activated receptor γ (PPARγ), consistent with previous reports showing steatosis is associated with an increase in PPARγ expression in mice with congenital loss of hepatic GH signaling. PPARγ is thought to be an important driver of steatosis by enhancing DNL, as well as increasing the uptake and esterification of extrahepatic fatty acids (FAs). In order to determine whether hepatic PPARγ is critical for the rapid development of steatosis in the aLivGHRkd mouse model, we have generated aLivGHRkd mice, with or without PPARγ (ie, adult-onset, hepatocyte-specific double knockout of GHR and PPARγ). Hepatic PPARγ was not required for the rapid increase in liver triglyceride content or FA indexes of DNL (16:0/18:2 and 16:1/16:0). However, loss of hepatic PPARγ blunted the rise in fatty acid translocase/CD36 and monoacylglycerol acyltransferase 1 expression induced by aLivGHRkd, and this was associated with a reduction in the hepatic content of 18:2. These results suggest that the major role of PPARγ is to enhance pathways critical in uptake and reesterification of extrahepatic FA. Because FAs have been reported to directly increase PPARγ expression, we speculate that in the aLivGHRkd mouse, the FA produced by DNL enhances the expression of PPARγ, which in turn increases extrahepatic FA uptake, thereby further enhancing PPARγ activity and exacerbating steatosis overtime.

Panhypopituitarism due to Absence of the Pituitary Stalk: A Rare Aetiology of Liver Cirrhosis

Studies have established a relationship between hypothalamic-pituitary dysfunction and the onset of liver damage, which may occasionally progress to cirrhosis. Patients with hypopituitarism can develop a metabolic syndrome-like phenotype. Insulin resistance is the main pathophysiological axis of metabolic syndrome and is the causal factor in the development of nonalcoholic fatty liver disease (NAFLD). We present the case of a young patient with liver cirrhosis of unknown aetiology that was finally attributed to panhypopituitarism.

Fatty Liver Index Associates with Relative Sarcopenia and GH/ IGF- 1 Status in Obese Subjects

Introduction

Recently the association between hepatic steatosis and sarcopenia has been described. GH/IGF-1 axis has been postulated to play a role in linking fatty liver and low muscle mass. The aim of our study was to explore the association between fatty liver index, sarcopenic obesity, insulin sensitivity, and GH/IGF-1 status.

Methods

427 subjects [age: 45.65±13.94 years, BMI: 36.92±6.43 kg/m²] were enrolled. Participants were divided into three groups: fatty liver index (FLI) <20, 20≥FLI<60, and FLI≥60. Body composition was assessed by DXA. The truncal fat mass (TrFM) to appendicular skeletal muscle (ASM) ratio was used as an indicator of sarcopenic obesity. ISI-Matsuda index was used.

Results

BMI, fat mass, and the TrFM/ASM ratio were higher in subjects with FLI≥60. GH, IGF-1 and ISI-Matsuda were lower in the high FLI group (all p<0.05). A significantly positive correlation between FLI and TrFM/ ASM ratio (r = 0.221, p<0.001) was found, whereas FLI levels were negatively correlated with ISI- Matsuda (r = -0.335, p<0.001), GH (r = -0.200, p = 0.006), and IGF- 1 levels (r = -0.157, p = 0.028). Stepwise linear regression analysis showed that GH levels were significantly negatively correlated with FLI, while the TrFM/ ASM ratio was positively associated with FLI, after adjustment for age, BMI, total fat mass, truncal fat mass, fat- free mass, and ISI- Matsuda.

Conclusions

Impairment of GH/IGF-1 axis seems to be associated to the risk of the development of sarcopenic obesity and ectopic fat deposition in the liver. Metabolic and hormonal derangements as determinants of ectopic fat deposition and body composition deserve to be evaluated in obese subjects.

Growth Hormone Inhibits Hepatic De Novo Lipogenesis in Adult Mice

Patients with nonalcoholic fatty liver disease (NAFLD) are reported to have low growth hormone (GH) production and/or hepatic GH resistance. GH replacement can resolve the fatty liver condition in diet-induced obese rodents and in GH-deficient patients. However, it remains to be determined whether this inhibitory action of GH is due to direct regulation of hepatic lipid metabolism. Therefore, an adult-onset, hepatocyte-specific, GH receptor (GHR) knockdown (aLivGHRkd) mouse was developed to model hepatic GH resistance in humans that may occur after sexual maturation. Just 7 days after aLivGHRkd, hepatic de novo lipogenesis (DNL) was increased in male and female chow-fed mice, compared with GHR-intact littermate controls. However, hepatosteatosis developed only in male and ovariectomized female aLivGHRkd mice. The increase in DNL observed in aLivGHRkd mice was not associated with hyperactivation of the pathway by which insulin is classically considered to regulate DNL. However, glucokinase mRNA and protein levels as well as fructose-2,6-bisphosphate levels were increased in aLivGHRkd mice, suggesting that enhanced glycolysis drives DNL in the GH-resistant liver. These results demonstrate that hepatic GH actions normally serve to inhibit DNL, where loss of this inhibitory signal may explain, in part, the inappropriate increase in hepatic DNL observed in NAFLD patients.

Higher estimated net endogenous Acid production may be associated with increased prevalence of nonalcoholic Fatty liver disease in chinese adults in Hong Kong

Nonalcoholic fatty liver disease (NAFLD) has been associated with reduced growth hormone levels and signaling. Such hormonal changes also occur in metabolic acidosis. Since mild metabolic acidosis can be diet induced, diet-induced acid load may constitute a nutritional factor with possible influence on NAFLD development. This study explored whether a higher diet-induced acid load is associated with an increased likelihood of NAFLD. Apparently healthy Chinese adults (330 male, 463 female) aged 19-72 years were recruited through population screening between 2008 and 2010 in a cross-sectional population-based study in Hong Kong. Estimated net endogenous acid production (NEAP) was calculated using Frassetto’s method and potential renal acid load (PRAL) was calculated using Remer’s method based on dietary data from a food frequency questionnaire. NAFLD was defined as intrahepatic triglyceride content at >5% by proton-magnetic resonance spectroscopy. Possible advanced fibrosis was defined as liver stiffness at >7.9 kPa by transient elastography. Multivariate logistic regression models were used to examine the association between each measure of dietary acid load and prevalent NAFLD or possible advanced fibrosis with adjustment for potential anthropometric and lifestyle factors. 220 subjects (27.7%) were diagnosed with NAFLD. Estimated NEAP was positively associated with the likelihood of having NAFLD after adjustment for age, sex, body mass index, current drinker status and the presence of metabolic syndrome [OR (95% CI) = 1.25 (1.02-1.52), p = 0.022]. The association was slightly attenuated but remained significant when the model was further adjusted for other dietary variables. No association between PRAL and NAFLD prevalence was observed. Both estimated NEAP and PRAL were not associated with the presence of possible advance fibrosis. Our findings suggest that there may be a modest association between diet-induced acid load and NAFLD. More studies are needed to ascertain the link between diet-induced acid load and NAFLD and to investigate the underlying mechanisms.

Liver status in congenital, untreated, isolated GH deficiency

Nonalcoholic fatty liver disease (NAFLD) is known to be associated with insulin resistance, atherosclerosis, and low serum IGF1 levels. We have described a large cohort of patients with isolated GH deficiency (IGHD) due to the c.57+1G→A mutation in the GHRH receptor gene. These subjects have increased insulin sensitivity (IS), delayed atherosclerosis, and normal longevity. We hypothesized that, despite visceral obesity, NAFLD would be absent or mild due to the increased IS. To assess the prevalence and severity of NAFLD in adult subjects with lifetime, congenital, untreated IGHD, we studied 22 IGHD adults and 25 controls (COs) matched for age and sex. NAFLD was assessed by a comprehensive liver function panel, and ultrasonographic pattern (hyperechogenic pattern, HP) coded as follows: 0, absent; 1, mild; 2, moderate; and 3, severe. Compared with COs, IGHD individual had lower serum IGF1 (P<0.0001), higher total cholesterol (P=0.027), lower prothrombin time (P=0.017), and similar activated partial thromboplastin time and fibrinogen values. Alanine transaminase (ALT) values were similar in the two groups, but aspartate transaminase was higher in IGHD (P=0.013). However, more IGHD subjects (7/22) than COs (3/23) had ALT above the upper limit of normal (P=0.044). The prevalence of NAFLD was higher in IGHD than COs (61 vs 29%, P=0.032), and the HP score was higher in IGHD than COs (P=0.041), but severe NAFLD was not observed in any IGHD (or CO) individual. Liver HP score is increased in lifetime, untreated, congenital IGHD, but the increase in transaminases is mild, suggesting a lack of advanced forms of NAFLD.

GH administration rescues fatty liver regeneration impairment by restoring GH/EGFR pathway deficiency

GH pathway has been shown to play a major role in liver regeneration through the control of epidermal growth factor receptor (EGFR) activation. This pathway is down-regulated in nonalcoholic fatty liver disease. Because regeneration is known to be impaired in fatty livers, we wondered whether a deregulation of the GH/EGFR pathway could explain this deficiency. Hepatic EGFR expression and triglyceride levels were quantified in liver biopsies of 32 obese patients with different degrees of steatosis. We showed a significant inverse correlation between liver EGFR expression and the level of hepatic steatosis. GH/EGFR down-regulation was also demonstrated in 2 steatosis mouse models, a genetic (ob/ob) and a methionine and choline-deficient diet mouse model, in correlation with liver regeneration defect. ob/ob mice exhibited a more severe liver regeneration defect after partial hepatectomy (PH) than methionine and choline-deficient diet-fed mice, a difference that could be explained by a decrease in signal transducer and activator of transcription 3 phosphorylation 32 hours after PH. Having checked that GH deficiency accounted for the GH signaling pathway down-regulation in the liver of ob/ob mice, we showed that GH administration in these mice led to a partial rescue in hepatocyte proliferation after PH associated with a concomitant restoration of liver EGFR expression and signal transducer and activator of trnascription 3 activation. In conclusion, we propose that the GH/EGFR pathway down-regulation is a general mechanism responsible for liver regeneration deficiency associated with steatosis, which could be partially rescued by GH administration.

Extrahepatic complications of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease, and is strongly associated with the metabolic syndrome. In the last decade, it has become apparent that the clinical burden of NAFLD is not restricted to liver-related morbidity or mortality, and the majority of deaths in NAFLD patients are related to cardiovascular disease (CVD) and cancer. These findings have fuelled concerns that NAFLD may be a new, and added risk factor for extrahepatic diseases such as CVD, chronic kidney disease (CKD), colorectal cancer, endocrinopathies (including type 2 diabetes mellitus [T2DM] and thyroid dysfunction), and osteoporosis. In this review we critically appraise key studies on NAFLD-associated extrahepatic disease. There was marked heterogeneity between studies in study design (cross-sectional versus prospective; sample size; presence/absence of well-defined controls), population (ethnic diversity; community-based versus hospital-based cohorts), and method of NAFLD diagnosis (liver enzymes versus imaging versus biopsy). Taking this into account, the cumulative evidence to date suggests that individuals with NAFLD (specifically, nonalcoholic steatohepatitis) harbor an increased and independent risk of developing CVD, T2DM, CKD, and colorectal neoplasms. We propose future studies are necessary to better understand these risks, and suggest an example of a screening strategy.