title: [Tumor necrosis factor-α, insulin resistance, the lipoprotein metabolism and obesity in humans].
abstract: In the obese adipose tissue produces proinflammatory molecules as tumor necrosis factor-α, which has local effects on adipocyte physiology and systemic effects in other organs. Many studies linking TNF-α, obesity, insulin resistance and lipid metabolism have been conducted in rats, rabbits and dogs, but the results observed in several of these studies have been conflicting and many of them have not been able to reproduce in humans, which on human makes difficult the interpretation of the effect of TNF-α on human metabolism.
  
  
  OBJECTIVE
  To conduct a systematic review of human studies which relates, TNF-α insulin resistance and lipoprotein metabolism.
  
  
  METHODS
  We searched the PubMed database for studies in humans, human tissue and human cell lines linking TNF-α, obesity, insulin resistance and lipoprotein.
  
  
  RESULTS
  There is a increased production of TNF-α on adipose tissue of obese. TNF-α decreases the cellular response to insulin in adipocytes, hepatocytes and human muscle cells. There is an increase of TNF-α in patients with dyslipidemia, and inactivation of TNF-α affects lipid metabolism. In human hepatocytes, TNF-α inhibits expression of APO AI, which may decrease the secretion of high density lipoproteins. TNF-α affects the excretion of cholesterol by inhibiting the enzyme cholesterol-7α-hydroxylase in hepatocytes.
  
  
  CONCLUSIONS
  TNF-α decreases the cellular response to insulin, and has effects on the metabolism of cholesterol and lipoproteins in humans. A better understanding of the mechanisms of the inflammatory response induced obesity in humans, can lead to identifying new therapeutic targets that can prevent the complications associated with obesity.
authors.affiliation: Departamento de Bioquímica, Escuela de Ciencias Biomédicas y Tecnológicas, Facultad de Ciencias de la Salud, Universidad de Carabobo, Valencia, Estado Carabobo, Venezuela. mmramirez@uc.edu.ve
authors.forename: Ma M
authors.initials: MM
authors.lastname: Ramírez Alvarado
authors.forename: C
authors.initials: C
authors.lastname: Sánchez Roitz
mesh_terms: D017667:Adipocytes / Q000378:metabolism; D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D004285:Dogs; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008074:Lipoproteins / Q000378:metabolism* / Q000502:physiology*; D032342:Muscle Cells / Q000378:metabolism; D009765:Obesity / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000502:physiology*
chemical_list: D008074:Lipoproteins; D014409:Tumor Necrosis Factor-alpha