Neuropeptide stimulation of physiological and immunological responses in precision-cut lung slices

Organotypic lung slices, sometimes known as precision-cut lung slices (PCLS), provide an environment in which numerous cell types and interactions can be maintained outside the body (ex vivo). PCLS were maintained ex vivo for up to a week and demonstrated health via the presence of neurons, maintenance of tissue morphology, synthesis of mucopolysaccharides, and minimal cell death. Multiple phenotypes of neuronal fibers were present in lung slices with varied size, caliber, and neurotransmitter immunoreactivity. Of the neuropeptides present in fibers, calcitonin gene-related peptide (CGRP) was the most prevalent. Exposing PCLS to recombinant CGRP resulted in the proliferation and dispersion of CD19⁺ B cells in slices taken selectively from females. The number of granules containing immunoreactive (ir) surfactant protein C (SPC), which are representative of alveolar type 2 cells, increased in slices from females within 24 h of exposure to CGRP. Additionally, ir-SPC granule size increased in slices from males and females across 48 h of exposure to CGRP. Exposure of PCLS to exogenous CGRP did not alter the number of solitary pulmonary neuroendocrine cells (PNEC) but did result in neuroendocrine bodies that had significantly more cells. Neuronal fiber numbers were unchanged based on ir-peripherin; however, ir-CGRP became non-detectable in fibers while unchanged in PNECs. The effects of exogenous CGRP provide insight into innate immune and neuroendocrine responses in the lungs that may be partially regulated by neural fibers. The sex-dependent nature of these changes may point to the basis for sex-selective outcomes among respiratory diseases.