Mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2-dependent pathways are essential for CD8+...

Ligation of the leukotriene B(4) (LTB(4)) receptor 1 on effector memory CD8(+) T cells by LTB(4) is important for the recruitment of CD8(+) T cells into the airways, which appears central to the induction of airway hyperresponsiveness (AHR) and allergic inflammation. Phosphorylation of extracellular signal-regulated kinase (ERK) is important in activation and cytokine production from many cell types.

The roles of ERKs in effector CD8(+) T-cell function and on CD8(+) T cell-mediated AHR were determined.

Effector CD8(+) T cells were generated from OVA(257-264) (SIINFEKL) peptide-primed mononuclear cells from OT-1 mice. The effects of U0126, an ERK inhibitor, on effector CD8(+) T-cell function and on CD8(+) T cell-mediated AHR and allergic inflammation were examined.

Pretreatment of effector CD8(+) T cells with U0126 suppressed anti-CD3/anti-CD28-induced ERK1/2 phosphorylation and cytokine production, but did not affect LTB(4)-induced Ca(2+) mobilization or chemotaxis. Adoptive transfer of U0126-treated CD8(+) T cells into sensitized mice before secondary allergen challenge resulted in significant decreases in AHR, eosinophilic inflammation, goblet cell metaplasia, and IL-5 and IL-13 levels in bronchoalveolar lavage fluid of recipient mice. The number of transferred CD8(+) T cells accumulating in bronchoalveolar lavage fluid or lungs was unaffected by treatment.

ERK1/2-dependent pathways are essential for the effector functions of CD8(+) T cells, including T(H)2 cytokine production, allergic inflammation, and development of AHR. Inhibition of ERK1/2 signaling has potential therapeutic benefit in preventing CD8(+) T cell-mediated AHR.