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CC16-TNF-α negative feedback loop formed between Clara cells and normal airway epithelial cells protects against diesel exhaust particles exposure-induced inflammation

CC16 is almost exclusively expressed in non-ciliated epithelial Clara cells, and widely used as a Clara cell marker. Diesel exhaust particles (DEPs), the fine particulate matters produced by diesel engines, cause or exacerbate airway-related diseases. Our previous study documented that DEP inhibits...

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Detalles Bibliográficos
Autores principales: Hu, Ting, Sun, Fenglan, Yu, Xinjuan, Li, Qinghai, Zhao, Long, Hao, Wanming, Han, Wei
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Impact Journals 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8386526/
https://www.ncbi.nlm.nih.gov/pubmed/34339391
http://dx.doi.org/10.18632/aging.203356
Descripción
Sumario:CC16 is almost exclusively expressed in non-ciliated epithelial Clara cells, and widely used as a Clara cell marker. Diesel exhaust particles (DEPs), the fine particulate matters produced by diesel engines, cause or exacerbate airway-related diseases. Our previous study documented that DEP inhibits the CC16 expression in the immortalized mouse Clara cell line through methylation of C/EBPα promoter. However, the molecular mechanism by which DEP regulates CC16 secretion is unclear. Here, we isolated CC16 containing Clara cells (CC16(+)) from human distal lung, and found that DEP inhibited CC16 secretion from CC16(+) cells via methylation of C/EBPα and inhibition of Munc18b transcription. CC16(+) cell conditioned media containing different concentrations of CC16 was prepared and used for culture of airway epithelial cells BEAS-2B with no expression of CC16. A positive correlation was observed between CC16 level and DEP-induced autophagy activity, and a negative correlation between CC16 level and DEP-induced pro-inflammatory cytokine TNF-α, IL-6, and IL-8 level, suggesting that CC16 might mitigate DEP-induced inflammation via promoting autophagy in BEAS-2B cells. This result was further confirmed by adding recombinant CC16 to BEAS-2B cells exposed to DEP. Moreover, CC16 level was significantly increased when CC16(+) cells were cultured in BEAS-2B cell conditioned medium containing TNF-α or the normal medium supplemented with recombinant TNF-α, suggesting that TNF-α induced CC16 production and secretion from CC16(+) cells. Collectively, these data point that CC16 and TNF-α form a negative feedback loop, and this negative feedback loop between Clara cells and normal airway epithelial cells protects against DEP exposure-induced inflammation.