TRPM8 channel augments T-cell activation and proliferation

The transient receptor potential melastatin 8 (TRPM8) is an ion channel that has been widely studied as a cold-sensitive nociceptor. However, its importance in nonneuronal cells is mostly unexplored. Here, we describe the presence and functional significance of endogenous TRPM8, a nonselective Ca²⁺ -channel in T cell functions. The major pool of TRPM8 resides at the T cell surface and its surface accumulation significantly increases in activated T cells. TRPM8 activation synergizes with T-cell receptor (TCR) stimulation to increase CD25, CD69 levels and enhances secretion of proinflammatory cytokine tumor necrosis factor. However, TRPM8 inhibition does not restrict TCR stimulation mediated activation of T cells, indicating that unlike the heat-sensitive TRPV1 and TRPV4 channels, the cold-sensitive TRPM8 channel may be dispensable during T-cell activation, at least in mice. In this study, we demonstrate that TRPM8 promotes TCR-induced intracellular calcium increase. TRPM8 activation is beneficial for T-cell activation and differentiation into effector cells. TRPM8 inhibition during the T-cell activation process may lead to altered phenotype and reduced proliferation, without affecting cell viability. These results collectively establish TRPM8 as a functional calcium channel whose activation may be utilized for mounting an effective immune response. The findings of this study will be relevant to the regulation and response of T cells during cell-mediated immunity. These results will likely further our understanding on the role of ion channels in T-cell activation.