An Initial Exploration Of PNECs-CGRP-immune Cell Axis In PM2.5-associated Chronic Obstructive Pulmonary Disease

Background:Chronic obstructive pulmonary disease(COPD)is a heterogeneous disease with multiple etiologies and a complex pathogenesis.The relationship between PM2.5 as a major air pollutant and COPD has received increasing attention as environmental problems become increasingly serious.The neuroendocrine system has an extremely important role in the neuroimmune system of the lung,especially the interaction between neuroendocrine cells(PNECs),the "sensory outposts" of the lung,and CGRP is associated with various lung diseases.However,the specific mechanisms of their roles in the development of COPD have not been elucidated.The aim of this study is to investigate the changes in the number and distribution of PNECs in the lungs of mice exposed to PM2.5,and to clarify the effects of PM2.5 exposure on the secretion of neuropeptides in the lungs and the possible ways in which CGRP regulates the neuroimmune regulation of immune target cells,so as to provide a more effective therapeutic direction for the prevention of PM2.5-related chronic obstructive pulmonary disease.Method:Part ⅠThe effect of long-term PM2.5 exposure on the lung function of mice was investigated by examining the lung function of mice in the PM2.5 long-term exposure group;the effect of long-term PM2.5 exposure on the alveolar structure of mice was also analyzed by HE staining of lung sections of mice exposed to PM2.5 long-term,which demonstrated that long-term PM2.5 exposure could lead to a decrease in lung function and destruction of alveolar structure in mice;then the lung function of mice was decreased by using To further investigate the distribution of pulmonary neuroendocrine cells(PNECs),an important source of CGRP,in the lungs of mice exposed to PM2.5 for a long period of time,the distribution of PNECs in the lungs of mice exposed to PM2.5 was determined by immunofluorescence and silver-loving staining of mouse lung sections.In this study,the distribution of PNECs in mouse lungs was clarified by immunofluorescence and silverophilic staining of mouse lung sections,and finally the relationship between PNECs and CGRP was clarified by immunofluorescence co-localization.Part ⅡThe possible pathways involved in pulmonary inflammation by PM2.5-stimulated lung macrophages were investigated by detecting the secretion of inflammatory factors and other cytokines by macrophages after PM2.5 induction by ELISA.The PM2.5-induced macrophages were then co-cultured with CGRP,thereby exploring the role of the neuropeptide-immune cell axis constituted by CGRP and PM2.5-induced macrophages in chronic airway inflammation.ResultPart Ⅰ:Long-term PM2.5 exposure significantly impaired lung function and promoted chronic airway inflammation and caused disruption of normal alveolar structure in mice,and emphysema-like lesions,including a significant increase in mean alveolar linear intercept and mean alveolar area,were observed in HE staining of lung sections from PM2.5 chronically exposed mice(P<0.05).In addition,long-term PM2.5 exposure resulted in significant elevation of alveolar lavage fluid neuropeptides(CGRP,GABA)and inflammatory factors(IL-1β,TNFα,IL-6)in mice(P<0.05).These results suggest that long-term stimulation of PM2.5 can lead to an increase in the number of PNECs in the lungs and thus to an increase in the CGRP content in the lungs,which also suggests a link between the PNECSneuropeptide axis and the development of slow-onset lung disease.This also suggests that there is an inextricable relationship between the PNECS-neuropeptide axis and the development of slow-onset lung disease.Part Ⅱ:Compared with the blank control group,the anti-inflammatory factor IL10 was significantly lower in both the experimental and experimental control groups(P<0.05),suggesting that PM2.5 may promote airway inflammation by inhibiting IL-10 production,while secretion of IL-1β and IL-6 by macrophages was significantly increased in the experimental group after stimulation by CGRP compared with the experimental control group(P<0.05).In conclusion,the neuropeptide immune cell axis composed of CGRP-macrophages may have a very critical role in the PM2.5-induced neuroinflammatory process.Conclusion1.PM2.5 exposure caused an abnormal increase in the number of PNECs in the small airways of mouse lungs,which induced massive secretion of CGRP leading to chronic neuroinflammation in lung.2.PM2.5 exposure induced a disruption of neuroimmune regulation of the PNECs-CGRP-macrophage axis,which in turn induced chronic obstructive pulmonary disease.