Protein catabolism in advanced renal disease: role of cytokines.
BACKGROUND
Protein energy wasting is a maladaptive metabolic state often associated with inflammation, which is common in patients with chronic kidney disease (CKD).


METHODS
A literature search was performed using MEDLINE and the reference lists of relevant review articles. The following key words were used in the MEDLINE search: "cytokines", "inflammation", "protein metabolism", "acute-phase protein", "cachexia", "chronic kidney disease", "end-stage renal disease" and "hemodialysis". The search was limited to English-language articles.


RESULTS
While experimental models have shown that uremic animals are more prone for proteolysis, the results from the human studies are controversial. Intradialytic loss of amino acids and activation of proinflammatory cytokines lead to protein catabolism during hemodialysis (HD). At the whole-body level, intradialytic parenteral nutrition (IDPN) increases protein synthesis and decreases proteolysis. Amino acid infusion during HD increases muscle protein synthesis, but does not decrease protein catabolism. Activation of interleukin-6 during HD induces protein catabolism, impairs amino acid utilization for protein synthesis and increases acute-phase protein synthesis.


CONCLUSIONS
The changes in albumin, fibrinogen and muscle protein kinetics during HD could be due to competing and complementary effects of availability of amino acids and activation of proinflammatory cytokines.
Fleet
M
M
Department of Medicine/Nephrology, University of New Mexico, Health Sciences Center, Albuquerque, NM, USA.
Osman
F
F
Komaragiri
R
R
Fritz
A
A
D
D000418:Albumins / Q000096:biosynthesis; D000596:Amino Acids / Q000378:metabolism; D002100:Cachexia / Q000378:metabolism; D016207:Cytokines / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D005340:Fibrinogen / Q000096:biosynthesis; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy; D044342:Malnutrition / Q000378:metabolism; D009124:Muscle Proteins / Q000096:biosynthesis*; D006435:Renal Dialysis
D000418:Albumins; D000596:Amino Acids; D016207:Cytokines; D009124:Muscle Proteins; D005340:Fibrinogen