Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation: a randomized clinical trial

Fatty liver is associated with an increased risk of diabetes and cardiovascular disease - Evidence from three different disease models: NAFLD, HCV and HIV

Fatty liver, which frequently coexists with necro-inflammatory and fibrotic changes, may occur in the setting of nonalcoholic fatty liver disease (NAFLD) and chronic infections due to either hepatitis C virus (HCV) or human immunodeficiency virus (HIV). These three pathologic conditions are associated with an increased prevalence and incidence of cardiovascular disease (CVD) and type 2 diabetes (T2D). In this multidisciplinary clinical review, we aim to discuss the ever-expanding wealth of clinical and epidemiological evidence supporting a key role of fatty liver in the development of T2D and CVD in patients with NAFLD and in those with HCV or HIV infections. For each of these three common diseases, the epidemiological features, pathophysiologic mechanisms and clinical implications of the presence of fatty liver in predicting the risk of incident T2D and CVD are examined in depth. Collectively, the data discussed in this updated review, which follows an innovative comparative approach, further reinforce the conclusion that the presence of fatty/inflamed/fibrotic liver might be a shared important determinant for the development of T2D and CVD in patients with NAFLD, HCV or HIV. This review may also open new avenues in the clinical and research arenas and paves the way for the planning of future, well-designed prospective and intervention studies.

Metabolic Complications and Glucose Metabolism in HIV Infection: A Review of the Evidence

HIV infection and antiretroviral therapy (ART) use are associated with perturbations in glucose and lipid metabolism. Increasing incidence of diabetes, cardiovascular disease, and obesity highlights the need for early identification and treatment of metabolic dysfunction. Newer ART regimens are less toxic for cellular function and metabolism but have failed to completely eliminate metabolic dysfunction with HIV infection. Additional factors, including viral-host interactions, diet, physical activity, non-ART medications, and aging may further contribute to metabolic disease risk in the HIV setting. We summarize the recent literature regarding the impact on metabolic function of HIV infection, ART, and pharmaceutical or lifestyle prescriptions.

Obesity in patients with HIV infection: epidemiology, consequences and treatment options

Even though wasting used to characterize patients with HIV infection prior to the antiretroviral therapy (ART) era, obesity is becoming increasingly prevalent in this population. Areas covered: In the present review, we discuss the epidemiology, consequences and treatment options for obesity in patients with HIV infection. Expert commentary: Obesity exerts a multitude of detrimental cardiometabolic effects and appears to contribute to the increasing cardiovascular mortality of this population. However, there are very limited data on the optimal management of obesity in patients with HIV infection. Given the potential for interactions between antiobesity agents and ART that might compromise viral control, lifestyle changes should represent the cornerstone for the prevention and management of obesity in HIV infection.

Pathophysiology and management of cardiovascular disease in patients with HIV

Results from several studies have suggested that people with HIV have an increased risk of cardiovascular disease, especially coronary heart disease, compared with people not infected with HIV. People living with HIV have an increased prevalence of traditional cardiovascular disease risk factors, and HIV-specific mechanisms such as immune activation. Although older, more metabolically harmful antiretroviral regimens probably contributed to the risk of cardiovascular disease, new data suggest that early and continuous use of modern regimens, which might have fewer metabolic effects, minimises the risk of myocardial infarction by maintaining viral suppression and decreasing immune activation. Even with antiretroviral therapy, however, immune activation persists in people with HIV and could contribute to accelerated atherosclerosis, especially of coronary lesions that are susceptible to rupture. Therefore, treatments that safely reduce inflammation in people with HIV could provide additional cardiovascular protection alongside treatment of both traditional and non-traditional risk factors.

Novel Approaches to Targeting Visceral and Hepatic Adiposities in HIV-Associated Lipodystrophy

Visceral and hepatic adiposities have been associated with both cardiovascular and liver disease and are of concern in HIV-infected persons in the modern era of combination antiretroviral therapy (ART). The development of therapeutic targets to reduce visceral and hepatic adiposities in HIV-infected persons has been slow, because of early reports that attributed the excess adiposity to specific antiretroviral drugs. Visceral adiposity was initially thought to occur as part of a protease inhibitor-induced "HIV-associated lipodystrophy syndrome." Subsequent studies show that visceral adiposity is likely a result of effective ART, recovery of health, and the normal aging process. Visceral adiposity is an established risk factor for hepatic adiposity. Identifying drug targets for non-alcoholic fatty liver disease is under active investigation. The present review summarizes the recent literature on the pathogenesis of visceral and hepatic adiposities in HIV-infected persons, current therapeutic strategies, and novel interventions in HIV-infected and uninfected persons.

Ghrelin Actions on Somatotropic and Gonadotropic Function in Humans

Ghrelin, a 28 amino-acid octanoylated peptide predominantly produced by the stomach, was discovered to be the natural ligand of the type 1a GH secretagogue receptor (GHS-R1a). It was thus considered as a natural GHS additional to GHRH, although later on ghrelin has mostly been considered a major orexigenic factor. The GH-releasing action of ghrelin takes place both directly on pituitary cells and through modulation of GHRH from the hypothalamus; some functional antisomatostatin action has also been shown. However, ghrelin is much more than a natural GH secretagogue. In fact, it also modulates lactotroph and corticotroph secretion in humans as well as in animals and plays a relevant role in the modulation of the hypothalamic-pituitary-gonadal function. Several studies have indicated that ghrelin plays an inhibitory effect on gonadotropin pulsatility, is involved in the regulation of puberty onset in animals, and may regulate spermatogenesis, follicular development and ovarian cell functions in humans. In this chapter ghrelin actions on the GH/IGF-I and the gonadal axes will be revised. The potential therapeutic role of ghrelin as a treatment of catabolic conditions will also be discussed.

The past 10 years-new hormones, new functions, new endocrine organs

Since the publication of the first issue of this journal in November 2005, our understanding of the endocrine system has evolved, with the identification of novel hormones and novel endocrine roles for previously identified molecules. Here, we have asked six of our Advisory Board Members to comment on how these insights have led to the recognition that many organs and tissues that were not widely considered part of the classic endocrine system in the past have important endocrine functions.

Predictors of Treatment Response to Tesamorelin, a Growth Hormone-Releasing Factor Analog, in HIV-Infected Patients with Excess Abdominal Fat

BACKGROUND

Tesamorelin, a synthetic analog of human growth hormone-releasing factor, decreases visceral adipose tissue (VAT) in human immunodeficiency virus (HIV)-infected patients with lipodystrophy.

OBJECTIVES

1) To evaluate the utility of patient characteristics and validated disease-risk scores, namely indicator variables for the metabolic syndrome defined by the International Diabetes Federation (MetS-IDF) or the National Cholesterol Education Program (MetS-NCEP) and the Framingham Risk Score (FRS), as predictors of VAT reduction during tesamorelin therapy at 3 and 6 months, and 2) To explore the characteristics of patients who reached a threshold of VAT <140 cm2, a level associated with lower risk of adverse health outcomes, after 6 months of treatment with tesamorelin.

METHODS

Data were analyzed from two Phase 3 studies in which HIV-infected patients with excess abdominal fat were randomized in a 2:1 ratio to receive tesamorelin 2 mg (n = 543) or placebo (n = 263) subcutaneously daily for 6 months, using ANOVA and ANCOVA models.

RESULTS

Metabolic syndrome (MetS-IDF or MetS-NCEP) and FRS were significantly associated with VAT at baseline. Presence of metabolic syndrome ([MetS-NCEP), triglyceride levels >1.7 mmol/L, and white race had a significant impact on likelihood of response to tesamorelin after 6 months of therapy (interaction p-values 0.054, 0.063, and 0.025, respectively). No predictive factors were identified at 3 months. The odds of a VAT reduction to <140 cm2 for subjects treated with tesamorelin was 3.9 times greater than that of subjects randomized to placebo after controlling for study, gender, baseline body mass index (BMI) and baseline VAT (95% confidence interval [CI] 2.03; 7.44).

CONCLUSIONS

Individuals with baseline MetS-NCEP, elevated triglyceride levels, or white race were most likely to experience reductions in VAT after 6 months of tesamorelin treatment. The odds of response of VAT <140 cm2 was 3.9 times greater for tesamorelin-treated patients than that of patients receiving placebo.

Effects of growth hormone-releasing hormone on visceral fat, metabolic, and cardiovascular indices in human studies

Increased visceral adipose tissue (VAT) is associated with reductions in endogenous GH secretion, possibly as a result of hyperinsulinemia, increased circulating free fatty acid, increased somatostatin tone, and reduced ghrelin. Reduced GH may, in turn, further exacerbate visceral fat accumulation because of decreased hormone-sensitive lipolysis in this depot. Data from multiple populations demonstrate that both reduced GH and increased VAT appear to contribute independently to dyslipidemia, increased systemic inflammation, and increased cardiovascular risk. The reductions in GH in states of visceral adiposity are characterized by reduced basal and pulsatile GH secretion with intact pulse frequency. Treatment with GH-releasing hormone (GHRH) provides a means to reverse these abnormalities, increasing endogenous basal and pulsatile GH secretion without altering pulse frequency. This review describes data from HIV-infected individuals and individuals with general obesity showing that treatment with GHRH significantly reduces visceral fat, ameliorates dyslipidemia, and reduces markers of cardiovascular risk. Further research is needed regarding the long-term efficacy and safety of this treatment modality.

The effect of recombinant human growth hormone with or without rosiglitazone on hepatic fat content in HIV-1-infected individuals: a randomized clinical trial

BACKGROUND

Hepatic fat is related to insulin resistance (IR) and visceral adipose tissue (VAT) in HIV+ and uninfected individuals. Growth hormone (GH) reduces VAT but increases IR. We evaluated the effects of recombinant human GH (rhGH) and rosiglitazone (Rosi) on hepatic fat in a substudy of a randomized controlled trial.

METHODS

HIV+ subjects with abdominal obesity and IR (QUICKI≤0.33) were randomized to rhGH 3 mg daily, Rosi 4 mg twice daily, the combination or double placebo. Hepatic fat was measured by magnetic resonance spectroscopy, visceral fat by MRI and IR by frequently sampled intravenous glucose tolerance tests at baseline and week 12.

RESULTS

31 subjects were studied at both time points. Significant correlations between hepatic fat and VAT (r=0.41; P=0.02) and QUICKI (r=0.39; P<0.05) were seen at baseline. IR rose with rhGH but not Rosi. When rhGH treatment groups were combined, hepatic fat expressed as percentage change decreased significantly (P<0.05) but did not change in Rosi (P=0.71). There were no correlations between changes in hepatic fat and VAT (P=0.4) or QUICKI (P=0.6). In a substudy of 21 subjects, a trend was noticed between changes in hepatic fat and serum insulin-like growth factor-1 (IGF-1; P=0.09).

CONCLUSIONS

Hepatic fat correlates significantly with both VAT and IR, but changes in hepatic fat do not correlate with changes in VAT and glucose metabolism. Hepatic fat content is reduced by rhGH but Rosi has no effect. These results suggest an independent effect of GH or IGF-1 on hepatic fat. The study was registered at Clinicaltrials.gov (NCT00130286).

Risk of coronary heart disease in patients with HIV infection

The lives of individuals infected with HIV who have access to combination antiretroviral therapy (cART) are substantially prolonged, which increases the risk of developing non-AIDS comorbidities, including coronary heart disease (CHD). In Europe and the USA, individuals with HIV infection have a ∼1.5-fold increased risk of myocardial infarction relative to uninfected individuals. In Africa, the relative risk of myocardial infarction is unknown, but broadened access to life-extending cART suggests that rates of CHD will rise in this and other resource-constrained regions. Atherogenesis in HIV is affected by complex interactions between traditional and immune risk factors. cART has varied, regimen-specific effects on metabolic risk factors. Overall, cART seems to lessen proatherogenic immune activation, but does not eliminate it even in patients in whom viraemia is suppressed. Current strategies to decrease the risk of CHD in individuals infected with HIV include early initiation of cART regimens with the fewest metabolic adverse effects, and careful management of traditional CHD risk factors throughout treatment. Future strategies to prevent CHD in patients with HIV infection might involve the use of HIV-tailored CHD risk-prediction paradigms and the administration of therapies alongside cART that will further decrease proatherogenic HIV-specific immune activation.