A brain-lung circuit drives LPS-induced lung injury via sympathetic neutrophil axis

Acute respiratory distress syndrome (ARDS) is a fatal complication of sepsis. However, the neural mechanisms underlying the exacerbation of pulmonary inflammation during systemic infection remain largely undefined. We employed an intraperitoneal lipopolysaccharide (LPS)-induced systemic inflammatory lung injury model and found that systemic inflammation strongly activates corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus (PVN), whereas bilateral subdiaphragmatic vagotomy abolished this response. Chemogenetic inhibition of CRH^PVN neurons alleviated lung injury and the formation of neutrophil extracellular traps (NETs), whereas chemogenetic activation of CRH^PVN neurons exacerbated pathological damage through sympathetic efferent signaling. Additionally, in patients with septic ARDS, β2-adrenergic receptor (ADRB2) expression was upregulated on neutrophils, and ADRB2 signaling delayed neutrophil apoptosis through the PI3K/Akt pathway, whereas ADRB2 blockade promoted neutrophil apoptosis and attenuated lung injury. In summary, we delineate a dysregulated neuroimmune axis in LPS-induced lung injury: systemic inflammatory signals activate the vagal afferent-PVN-sympathetic circuit, which in turn drives a neutrophil-mediated ADRB2-PI3K/Akt signaling pathway that amplifies lung injury. Our study reveals a mechanistic basis for neuroregulatory intervention and indicates that targeting this Brain-lung pathway may offer new therapeutic strategies for ARDS.