Pulmonary neuroepithelial body-Agtr1a+ vagal sensory nerve axis and breathing control abnormalities in a novel BPD-mouse model

Neural control of breathing (nCOB) problems commonly complicate the postnatal development of preterm infants with bronchopulmonary dysplasia (BPD), but the underlying factors remain incompletely understood. A subpopulation of pulmonary vagal sensory (PSN) neurons expressing an angiotensin II receptor (Agtr1a + ) innervates CO2 and O2 sensitive clusters of lung neuroendocrine cells (neuroepithelial bodies (NEBs)) located along conducting airways. NEBs stimulate Agtr1a PSNs, providing direct sensory input to the brainstem, and NEBs are hyperplastic in infants succumbing to BPD. However, the role of the NEB-Agtr1a PSN axis on the nCOB in health and BPD remains unknown. Herein, we sought to test the hypothesis that the NEB-Agtr1a lung-brainstem axis is altered in association with poor nCOB in BPD. WT mice (n=14-16/group) were exposed to chronic neonatal 70% (P0-14 days of life), 90% O2 (P0-5), or normoxia (NX). Consistent with human BPD, 90% O2 caused worse alveolar simplification and hypoventilation, reflecting severe BPD infants. 70% O2 caused a milder yet still significant alveolar loss associated with compensatory hyperpnea, reflecting mild BPD infants. These observations occurred between P17-22, after correcting (generalized linear model) for body composition and heat production or O2 consumption, measured by whole-body plethysmography, NMR, and respirometry. Subsequent lung immunofluorescence indicated NEBs were significantly (ANOVA with Tukey; p<0.05) hyperplastic among 90HX, hypoventilating mice (70 NEBs) with 26.5 +/- 5.9 cells/NEB vs 9.8 +/- 0.8 cells/NEB in 70HX mice (149 NEBs) or 8.4 +/- 0.6 cells/NEB in NX mice (156 NEBs). A subsequent cohort of Agtr1a-Cre+ and Cre- mice were intratracheally treated with a retrograde(r)AAV to drive Agtr1a-specific expression of an excitatory synthetic receptor (Gq-DREADD) tagged with eGFP and subsequently activatable by a synthetic ligand (DCZ) by IP injection. Though DCZ caused minimal effects on breathing metrics during room air, hypoxic breathing frequency increased (25%) with a decrease (~25%) in the inner breath interval among Agtr1aCre+ (n=2) but not Cre- (n=2) NX mice. A subset of NX and 90 HX mice (3-4/group) were intratracheally treated with rAAV-tdTomato. Subsequent Western Blot of homogenized lung tissue revealed a significant reduction (~50%; p<0.05, t-test) in tdTomato among 90HX mice, indicating loss of Agtr1a innervation. This study establishes a novel application of chronic neonatal hyperoxia to model either mild or severe BPD with compensatory or decompensatory respiratory control in mice, respectively. Further, severe BPD is associated with NEB hyperplasia, loss of Agtr1a innervation, and poor nCOB, supporting our hypothesis. The NEB-Agtr1a axis may be a novel therapeutic target for improving nCOB in severe BPD. Neuroscience Research Center, Imagine More Award (3311232), Advancing Healthier Wisconsin REAC Award (5520640) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.