Neural input to the immune system can alter its ability to clear pathogens effectively. Patients suffering mild traumatic brain injury (mTBI) have shown reduced rates of pneumonia and a murine model replicated these findings, with better overall survival of TBI mice compared with sham-injured mice. To further investigate the mechanism of improved host response in TBI mice, this study developed and characterized a mild tail trauma model of similar severity to mild TBI. Both mild tail trauma and TBI induced similar systemic changes that normalized within 48 hours, including release of substance P. Examination of tissues showed that injuries are limited to the target tissue (ie, tail in tail trauma, brain in mTBI). Pneumonia challenge showed that mild TBI mice showed improved immune responses, characterized by the following: i) increased survival, ii) increased pulmonary neutrophil recruitment, iii) increased bacterial clearance, and iv) increased phagocytic cell killing of bacteria compared with tail trauma. Administration of a neurokinin-1ereceptor antagonist to block substance P signaling eliminated the improved survival of mTBI mice. Neurokinin-1ereceptor antagonism did not alter pneumonia mortality in tail trauma mice. These data show that immune benefits of trauma are specific to mTBI and that tail trauma is an appropriate control for future studies aimed at elucidating the mechanisms of improved innate immune responses in mTBI mice. Neural input exerts significant control on the ability of the immune system to clear pathogens effectively. Early studies have shown that stress has a profound detrimental effect on the immune response. 1 Psychologic or physiologic stress can result in dysregulation of these pathways, such as chronic activation, which ultimately leads to immunosuppression. 2 Activation of the vagus nerve also has been shown to induce powerful anti-inflammatory effects through the a7 nicotinic acetylcholine receptor. In severe traumatic brain injury (TBI) patients, it has been proposed that hyperactivity of the vagus depresses immune responses through strong dampening of proinflammatory mediator production. 3 In contrast to these studies showing that the neuroimmune axis decreases immune responses, our previous work documented that head trauma patients showed significantly reduced rates of pneumonia compared with blunt trauma patients. 4 A murine model of mild traumatic brain injury (mTBI) was able to reproduce these findings with enhanced resistance to bacterial pneumonia compared with sham injury mice. 4 mTBI mice showed improved survival, augmented pulmonary neutrophil recruitment, and reduced bacterial burdens compared with sham-injured mice. These findings show that neuroimmune modulation can show beneficial effects by improving immune function. Further investigation into the mechanisms by which mTBI augments the innate immune response could offer valuable insight into fighting infections in today's increasingly