The neuropeptide calcitonin gene related peptide alters lung physiology
Authors: Patlin Brielle , Tobet Stuart 
Published: May 2023

The objective of this study was to determine the role of the neuropeptide calcitonin gene related peptide (CGRP) on the physiology of the lungs. We hypothesized that exposure to the most prevalent neuropeptide in the lung would change cell populations in the lung relevant to disease. The neuroimmune axis is a recognized disease factor (Blake et. al., 2019, PMID:31213389). However, neurons that populate the lung are often overlooked in the study of respiratory diseases. These neurons consist of many different types relative to size, caliber of fibers, and neurotransmitters. Of the neuropeptides that are present in fibers, one of the most prevalent is CGRP. We confirmed the extent of these fibers in our model by visualizing a variety of neural populations using immunohistochemistry. CGRP antagonism has been important recently because of its therapeutic applications for migraine. However, CGRP effects in the lung are poorly understood. We developed an ex-vivo precision cut lung slice model in adult mice that maintains diverse cell types, proliferation, and death compared to those in an in-vivo respiratory system over five days. In this model, it was important to consider the glucose content of the culture media. Many commercial medias have a higher glucose content than would mimic physiological levels. In this model components of media, air liquid interface, and sex were considered as biological variables. After characterizing the baseline health of ex vivo slices over several days, 10μM CGRP was introduced to slices to assess three physiological responses. The area of immunoreactive (ir)-surfactant, a marker for type 2 pneumocytes—was 60% bigger in males than females in control mice and decreased in size in females by 80% but increased in males by 30% with CGRP treatment. Changes to surfactant populations may correlate with changes to breathing prevalent in respiratory disease. CD-19-ir B cell populations dispersed and increased by 120% in females compared to controls. In males B cell populations were consistent over time with CGRP treatment. B cells are integral to infection responses and the difference in innate B cell responses to CGRP may relate to the differential mortality between sexes from respiratory disease. Finally, loss of CGRP-ir fibers may not imply loss of fibers themselves since there was no change in ir-peripherin fibers. Since peripherin is an intermediate filament protein in peripheral neurons regardless of peptide localization it is likely that fiber anatomy did not change. Changes to all three of these traits are present in respiratory disease. This model will be used in the future in conjunction with viral diseases to assess changes relevant to neuropeptide release. Neuropeptide dependent changes may provide insight to how innate immune responses are regulated by neural fibers in the lungs. The sex dependent nature of these changes may also result in an explanation for sex selective outcomes for respiratory diseases. Anschutz Foundation Pandemic Preparedness Grant This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.