Effects of Lipopolysaccharide on T helper 2 Cytokine Expression in Adult Atopic Patients

Abstract

While lipopolysaccharide (LPS) is known to have a preventive effect on allergic inflammation, little is known about its effect on T helper (Th) 2 cytokine expression in human. We investigated the effect of LPS on the expression of Th2 cytokine as well as toll-like receptor (TLR) 4 in peripheral blood mononuclear cells (PBMCs) of adult atopic patients. PBMCs isolated from adult atopic patients and non-atopic controls were incubated with allergen or LPS or both. The mRNA expression of IL-4, IL-5, IL-9, IL-10, IL-13 and TLR4 were measured by quantitative realtime PCR. Allergen stimulation induced the expression of Th2 cytokines in PBMCs of adult atopic patients, but not in non-atopic controls. LPS stimulation induced the expression of IL-5 and IL- 10 in atopic adults, IL-5 and TLR4 in non-atopic controls. The expression of TLR4 to LPS was significantly lower in atopic adults than non-atopic controls. When PBMCs were stimulated with both allergen and LPS simultaneously, LPS didn't show the preventive effect on Th2 cytokine expression triggered by allergen in adult atopic patients. The low responsiveness to LPS compared to non-atopic controls may contribute to atopic mechanism in adult atopic patients, further evaluations are needed.