Neurogenic inflammation is believed to originate with the antidromic release of substance P, and of other neurokinins encoded by the preprotachykinin A (PPT-A) gene, from unmyelinated nerve fibers (C-fibers) following noxious stimuli. Consistent with this concept, we show here that selective sensory-fiber denervation with capsaicin and targeted deletion of the PPT-A gene protect murine lungs against both immune complex–mediated and stretch-mediated injuries. Reconstitution of PPT-A gene–deleted mice with WT bone marrow does not abrogate this protection, demonstrating a critical role for PPT-A gene expression by sensory neurons in pulmonary inflammation. Surprisingly, reconstitution of WT mice with PPT-A gene–deficient bone marrow also confers protection against pulmonary injury, revealing that PPT-A gene expression in hemopoietic cells has a previously unanticipated essential role in tissue injury. Taken together, these findings demonstrate a critical synergy between capsaicin-sensitive sensory fibers and hemopoietic cells in neurokinin-mediated inflammation and suggest that such synergy may be the basis for a stereotypical mechanism of response to injury in the respiratory tract.
Mara Chavolla-Calderón, Meggan K. Bayer, J. Julio Pérez Fontán