Urinary cytokines for assessing inflammation in HIV-associated wasting

The relationship between cytokines and HIV-related weight loss has not been well established. Unlike most cytokines that are secreted in a paracrine manner, IL-6, sTNFR-II, and IL-1ra are readily detected in the systemic circulation and serve as markers of the inflammatory response. Twenty-four-hour urine concentrations of these proteins are believed to provide an integrative assessment of their systemic levels over the preceding hours. We sought to determine whether spot measurements of IL-6, sTNFR-II, and IL-1ra could be related to subsequent 24 h concentrations and prior weight loss. Eighteen subjects with severe wasting (average BMI=18+/-3 kg/m2with 19+/-13 kg of weight loss) and six HIV-negative healthy subjects were tested. Compared to values in controls, 24-h urinary concentrations of the three proteins adjusted for creatinine excreted were elevated in 44%, 89%, and 72% of patients, respectively. Twenty-four-hour concentrations were highly correlated with the spot concentrations (r=0.80, 0.87, 0.84, respectively, P<0.001). IL-1ra concentrations (24 h and spot) were correlated with weight loss in the previous 6 months, lifetime rate of weight loss and the 6 month rate of weight loss (spot: r=0.66, 0.73, 0.68, respectively, P< or =0.001). These data suggest that spot urinary collections can be used to estimate 24 h excretion rates. This strategy may be useful in assessing the inflammatory response in HIV-associated wasting.