transforming-growth-factor-beta and HIV-Wasting-Syndrome

Wasting, or cachexia, is a significant, debilitating, and potentially life-threatening complication of HIV infection. It is associated with reduced strength and functional ability, reduced ability to withstand opportunistic infections, and increased risk of mortality. Although the incidence of HIV-associated wasting may have declined since the introduction of highly active antiretroviral therapy (HAART), it continues to be a concern in this patient population.. This paper reviews available data on the etiology and clinical impact of HIV-associated wasting, the role of the growth hormone/insulin-like growth factor-I axis in the pathophysiology of this condition, and the rationale for its treatment with recombinant human growth hormone (rhGH).. MEDLINE was searched for articles published in English through August 2007 using the terms HIV, wasting (and related terms), and growth hormone. Preference was given to clinical studies (including randomized clinical studies), meta-analyses, and guidelines. Review articles were evaluated and the bibliographies examined for additional relevant articles. The analysis was restricted to studies conducted in developed countries.. Alterations in the growth hormone/insulin like growth factor-I axis have been observed in patients with HIV-associated wasting, including elevated levels of the former and reduced levels of insulin-like growth factor I. In randomized, placebo-controlled studies, rhGH significantly improved lean body mass by approximately 3 kg compared with placebo (P < 0.001) and total body weight by approximately 3 kg (P < 0.001), and was associated with significant improvements in physical endurance and quality of life (P < 0.001). Common adverse events with rhGH therapy include blood glucose elevations, arthralgia (36.4%), myalgia (30.4%), and peripheral edema (26.1%), but these usually respond to dose reduction or drug discontinuation.. Physicians should be alert to the possibility of wasting in HIV-infected patients receiving HAART and should consider treatment to improve patients' stamina and quality of life. The evidence supports a role for rhGH in the treatment of patients with HIV-associated wasting. Regular blood glucose monitoring is advised when treating wasting with rhGH.

Topics: Adolescent; Adult; Antiretroviral Therapy, Highly Active; Body Composition; Cachexia; Child; Cytokines; Energy Metabolism; Growth Hormone; HIV Infections; HIV Wasting Syndrome; Human Growth Hormone; Humans; Insulin-Like Growth Factor I; Muscular Diseases; Myostatin; Proteins; Recombinant Proteins; Risk Factors; Signal Transduction; Testosterone; Transforming Growth Factor beta

Cachexia causes weight loss and increased mortality. It affects more than 5 million persons in the United States. Other causes of weight loss include anorexia, sarcopenia, and dehydration. The pathophysiology of cachexia is reviewed in this article. The major cause appears to be cytokine excess. Other potential mediators include testosterone and insulin-like growth factor I deficiency, excess myostatin, and excess glucocorticoids. Numerous diseases can result in cachexia, each by a slightly different mechanism. Both nutritional support and orexigenic agents play a role in the management of cachexia.

Topics: Aging; Anorexia; Arthritis, Rheumatoid; Cachexia; Chronic Disease; Cytokines; Glucocorticoids; HIV Wasting Syndrome; Humans; Insulin-Like Growth Factor I; Kidney Failure, Chronic; Myostatin; Neoplasms; Pulmonary Disease, Chronic Obstructive; Testosterone; Transforming Growth Factor beta; Weight Loss

There are no approved therapies for muscle wasting in children infected with human immunodeficiency virus (HIV), which portends poor disease outcomes. To determine whether a soluble ActRIIb receptor Fc fusion protein (ActRIIB.Fc), a ligand trap for TGF-β/activin family members including myostatin, can prevent or restore loss of lean body mass and body weight in simian immunodeficiency virus (SIV)-infected juvenile rhesus macaques (Macaca mulatta). Fourteen pair-housed, juvenile male rhesus macaques were inoculated with SIVmac239 and, 4 wk postinoculation (WPI) treated with intramuscular injections of 10 mg ⋅ kg(-1) ⋅ wk(-1) ActRIIB.Fc or saline placebo. Body weight, lean body mass, SIV titers, and somatometric measurements were assessed monthly for 16 wk. Age-matched SIV-infected rhesus macaques were injected with saline. Intervention groups did not differ at baseline. Gains in lean mass were significantly greater in the ActRIIB.Fc group than in the placebo group (P < 0.001). Administration of ActRIIB.Fc was associated with greater gains in body weight (P = 0.01) and upper arm circumference than placebo. Serum CD4(+) T-lymphocyte counts and SIV copy numbers did not differ between groups. Administration of ActRIIB.Fc was associated with higher muscle expression of myostatin than placebo. ActRIIB.Fc effectively blocked and reversed loss of body weight, lean mass, and fat mass in juvenile SIV-infected rhesus macaques.

Topics: Activin Receptors, Type II; Animals; Disease Models, Animal; Hematocrit; HIV Wasting Syndrome; Humans; Immunoglobulin Fc Fragments; Ligands; Macaca mulatta; Male; Muscle, Skeletal; Myostatin; Recombinant Fusion Proteins; RNA, Messenger; Simian Acquired Immunodeficiency Syndrome; Simian Immunodeficiency Virus; Transforming Growth Factor beta; Up-Regulation; Weight Gain

Myostatin, a member of the transforming growth factor-beta superfamily, is a genetic determinant of skeletal muscle growth. Mice and cattle with inactivating mutations of myostatin have marked muscle hypertrophy. However, it is not known whether myostatin regulates skeletal muscle growth in adult men and whether increased myostatin expression contributes to wasting in chronic illness. We examined the hypothesis that myostatin expression correlates inversely with fat-free mass in humans and that increased expression of the myostatin gene is associated with weight loss in men with AIDS wasting syndrome. We therefore cloned the human myostatin gene and cDNA and examined the gene's expression in the skeletal muscle and serum of healthy and HIV-infected men. The myostatin gene comprises three exons and two introns, maps to chromosomal region 2q33.2, has three putative transcription initiation sites, and is transcribed as a 3.1-kb mRNA species that encodes a 375-aa precursor protein. Myostatin is expressed uniquely in the human skeletal muscle as a 26-kDa mature glycoprotein (myostatin-immunoreactive protein) and secreted into the plasma. Myostatin immunoreactivity is detectable in human skeletal muscle in both type 1 and 2 fibers. The serum and intramuscular concentrations of myostatin-immunoreactive protein are increased in HIV-infected men with weight loss compared with healthy men and correlate inversely with fat-free mass index. These data support the hypothesis that myostatin is an attenuator of skeletal muscle growth in adult men and contributes to muscle wasting in HIV-infected men.

Topics: Adult; Animals; Base Sequence; Cattle; CHO Cells; Chromosome Mapping; Chromosomes, Human, Pair 2; Cloning, Molecular; Cricetinae; Exons; HIV Infections; HIV Wasting Syndrome; HIV-1; Humans; Introns; Male; Mice; Molecular Sequence Data; Muscle, Skeletal; Myostatin; Sequence Analysis, DNA; Transforming Growth Factor beta