The lung communication network

Abstract

The different types of cells in the lung, from the conducting airway epithelium to the alveolar epithelium and the pulmonary vasculature, are interconnected by gap junctions. The specific profile of gap junction proteins, the connexins, expressed in these different cell types forms compartments of intercellular communication that can be further shaped by the release of extracellular nucleotides via pannexin1 channels. In this review, we focus on the physiology of connexins and pannexins and describe how this lung communication network modulates lung function and host defenses in conductive and respiratory airways.

Fig. 1

Expression profile of Panx1 and principal connexins in the adult conducting airways. Hematoxylin and eosin-stained section of human tracheal mucosa illustrating the surface airway epithelium and the tracheal glands. The localization of connexins and pannexin1 is depicted by a color code and schematically represented below the photograph (Panx1, blue line; Cx26, red dots; Cx30, yellow dots; Cx31; purple dots; Cx32, green dots; Cx43, brown dots)

Fig. 2

Expression profile of Panx1 and principal connexins in the adult respiratory airways. Semithin section of human lungs illustrating the respiratory airway epithelium and its relation with the capillary bed. The localization of connexins and pannexin1 is depicted by a color code and schematically represented below the photograph (Panx1, blue line; Cx26, red dots; Cx32, green dots; Cx43, brown dots; Cx40, light blue dots; Cx46, pink dots)

Fig. 3

Principal functions of Panx1 and connexins in the adult conducting airways. The functions mediated by Cxs or Panx1 for given stimulus are indicated by a color code (ASL airway surface liquid, LXA4 lipoxin A4, ATP adenosine triphosphate)

Fig. 4

Principal functions of Panx1 and connexins in the adult respiratory airways. The functions mediated by Cxs or Panx1 for given stimulus are indicated by a color code. The basal lamina separating the air-blood compartments is indicated by a blue dashed line (ADO adenosine, ATP adenosine triphosphate, CD73 ecto-5′-nucleotidase)