Weight loss, the gut and the inflammatory response in AIDS patients

The objective of this study was to test the hypothesis that the integrity of the large bowel wall in AIDS patients is compromised in a manner that favours the chronic translocation of bacteria and/or products of bacterial metabolism into the bloodstream. When such translocation occurs, it induces a characteristic stress/inflammatory response in the body. Urinary butyrate, a unique product of colonic microbial metabolism, was used to assess gut wall permeability. Excretion of the pro-inflammatory cytokine IL-6 in the urine was used as a marker for the stress/inflammatory response. Four groups of subjects were studied, controls (n = 12), HIV+ (n = 35) and AIDS patients with (n = 14) and without (n = 17) weight loss. Results: measurable amounts of interleukin 6 (IL-6) and butyrate were found in the urine of all subjects. There were no significant differences in IL-6 excretion between the controls (0.68 ± 0.64 pg/ml), asymptomatic HIV+ subjects (0.59 ± 0.37 pg/ml) and AIDS patients without weight loss (1.18 ± 0.33 pg/ml) but IL-6 levels were significantly higher in the AIDS group with weight loss (4.02 ± 1.26 pg/ml, P < 0.05). A similar pattern of results was found with interleukin 1 receptor antagonist (IL-1ra). Like IL-6 and (IL-1ra), urinary butyrate levels were increased in the AIDS patients with weight loss (2.83 ± 0.67 μmol/l) relative to the controls (1.31 ± 0.13 μmol/l, P < 0.05), with the HIV+ patients (1.65 ± 0.18 μmol/l) and AIDS patients without weight loss (1.90 ± 0.22 μmol/l) falling in between. The data are consistent with a low, but chronic rate of bacteria and/or bacterial products seeping across a compromised colonic wall causing a chronic low stress response in AIDS patients.