Glutamine as a modulator of the immune system of critical care patients: Effect on Toll-like receptor expression. A preliminary study

Objective We evaluated the expression of Toll-like receptors 2 and 4 (TLR-2 and TLR-4) in circulating monocytes from peripheral blood of critical care patients treated with and without glutamine. Because no research has been published to date on the effect of glutamine on TLR receptors in critical patients, it was determined in an initial sample of 30 patients. Methods This was a prospective, randomized, single-blind study with 15 patients assigned to receive parenteral nutrition with a daily glutamine supplement of 0.35 g/kg. The control group received isocaloric-isonitrogenous parenteral nutrition. Blood samples were extracted before beginning the treatment and at 5 and 14 d. Expressions of CD14, TLR-2, and TLR-4 were determined by flow cytometry. Levels of TLRs were expressed as mean fluorescence intensity (mfi). Results Basal characteristics were similar in both groups. The expressions of TLR-2 in the treatment group with glutamine were 4.67 ± 3.82 mfi before treatment, 3.91 ± 2.04 mfi at 5 d, and 4.28 ± 2.47 mfi at 14 d. The expressions of TLR-2 in the control group were 5.49 ± 3.20 mfi before treatment, 4.48 ± 2.15 mfi at 5 d, and 4.36 ± 2.36 mfi at 14 d. The expressions of TLR-4 in the treatment group were 1.65 ± 1.89 mfi before treatment, 1.23 ± 1.10 mfi at 5 d, and 1.77 ± 1.97 at 14 d. The expressions of TLR-4 in the control group were 1.51 ± 1.76 mfi before treatment, 1.36 ± 0.99 mfi at 5 d, and 1.26 ± 0.59 mfi at 14 d. Infections were detected in 11 patients who received glutamine and 13 control patients (P = 0.51). Conclusion In critical care patients, parenteral nutrition supplemented with glutamine does not increase the expression of TLR-2 or TLR-4 in peripheral blood monocytes.