Immunology
Neuronal Receptor VR1 Involved in Immune Cell Function
By Proceedings of the National Academy of Sciences
Mar 30, 2005, 06:45

Sreyashi Basu and Pramod Srivastava report that capsaicin, the spicy component of chili peppers, induces maturation in dendritic cells (DCs), key antigen-presenting cells of the immune system. In the nervous system, capsaicin and thermal heat work in a similar manner by activating the vanilloid receptor 1 (VR1) receptor on sensory neurons, explaining why capsaicin elicits a burning sensation.

In a previous study, Basu and Srivastava observed that heat stimulates DCs to mature, and they hypothesized that these immune cells also detect heat via the VR1 receptor pathway. In the current study, the researchers demonstrate that immature DCs in mice express the VR1 receptor.

When the immature DCs were treated with capsaicin to activate VR1, the DCs matured, as measured by up-regulation of antigen-presenting molecules. To test the functionality of VR1, the researchers exposed DCs from VR1+/+ and VR1�/� mice to either capsaicin or heat (41�C). DCs from VR1+/+ mice matured when exposed to heat or capsaicin, whereas DCs from VR1�/� mice matured in response to heat alone. Furthermore, injection of capsaicin into the skin caused DCs to migrate to draining lymph nodes in VR1+/+ mice but not VR1�/� mice. These data indicate that VR1 is not responsible for heat-induced maturation of DCs, but that capsaicin affects DC activity via VR1, demonstrating a common mechanistic pathway between neural and immune functions.

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