Activation of a nerve injury transcriptional signature in airway-innervating sensory neurons after lipopolysaccharide induced lung inflammation

Abstract

The lungs, the immune and nervous systems functionally interact to respond to respiratory environmental exposures and infections. The lungs are innervated by vagal sensory neurons of the jugular and nodose ganglia, fused together in smaller mammals as the jugular-nodose complex (JNC). While the JNC shares properties with the other sensory ganglia, the trigeminal (TG) and dorsal root ganglia (DRG), these sensory structures express differential sets of genes that reflect their unique functionalities. Here, we used RNAseq in mice to identify the differential transcriptomes of the three sensory ganglia types. Using a fluorescent retrograde tracer and fluorescence-activated cell sorting we isolated a defined population of airway-innervating JNC neurons and determined their differential transcriptional map after pulmonary exposure to lipopolysaccharide (LPS), a major mediator of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) after infection with Gram-negative bacteria or inhalation of organic dust. JNC neurons activated an injury response program leading to increased expression of gene products such as the G-protein coupled receptors, Cckbr, inducing functional changes in neuronal sensitivity to peptides, and Gpr151, also rapidly induced upon neuropathic nerve injury in pain models. Unique JNC-specific transcripts, present at only minimal levels in TG, DRG and other organs, were identified. These included TMC3, encoding for a putative mechanosensor, and Urotensin 2B, a hypertensive peptide. These findings highlight the unique properties of the JNC and reveal that ALI/ARDS rapidly induce a nerve-injury related state changing vagal excitability.\n\nSIGNIFICANCE STATEMENTThe lungs are innervated by sensory neurons of the jugular-nodose ganglia complex (JNC) that detect toxic exposures and interact with lung-resident cells and the immune system to respond to pathogens and inflammation. Here we report the expression of specific genes that differentiate these neurons from neurons in the other sensory ganglia, the trigeminal (TG) and dorsal root ganglia (DRG). Through nerve tracing we identified and isolated airway innervating JNC neurons and determined their differential transcriptional map after lung inflammation induced by a bacterial product, lipopolysaccharide (LPS). We observed the rapid activation of a nerve injury transcriptional program that increased nerve sensitivity to inflammation. This mechanism may result in more permanent nerve injury associated with chronic cough and other respiratory complications.