Persistent activation of TNFR1 on spinal cord interneurons contributes to immune dysfunction after spinal cord injury in rodents

Abstract

Abstract Spinal cord injury (SCI) is a devastating condition with 250,000 to 500,000 new cases globally each year. Respiratory infections, e.g., pneumonia and influenza, are the leading cause of death after SCI. For instance, an individual with SCI is 37 times more likely to become infected and hospitalized from the flu. Yet, the field has a poor understanding of how immune dysfunction arises after trauma to the central nervous system (CNS) and how altered neuro-immune communication impacts an individual’s outcome to infection. In humans and rodents, SCI leads to maladaptive changes in the spinal-sympathetic reflex (SSR) circuit which is crucial to sympathetic function. Soluble Tumor Necrosis Factor (sTNF) is a pro-inflammatory cytokine that is elevated in the CNS after SCI and remains elevated for several months after injury. We recently demonstrated that blocking TNFR1 activation in the CNS, using XPro1595, decreased the maladaptive excitability of SpINs in the SSR circuit leading to improved immune response to infection after SCI. We hypothesize that hyper-excitability of glutamatergic SpINs after SCI due to persistent TNFR1 activation contributes to immune dysfunction. To test this, we utilized viral mediated targeted knock-down of TNFR1 on excitatory SpINs, and demonstrated that inhibiting TNFR1 on excitatory interneurons contributes to improved immune function, including an increase in virus-specific T cells and decrease in viral load remaining in the lung after infection. Supported by grants from NIH (R01 NS111761) Supported by grants from NIH (R01 NS111761)