*2.1. P2X7*−/<sup>−</sup> *Mice Show Strongly Enhanced JAM-A Protein Level in the Lung Parenchyma*

We analyzed the mRNA expression and total protein content of JAM-A in lung tissue homogenates of WT and P2X7−/<sup>−</sup> mice (Figure 1).

**Figure 1.** Frozen sections of mouse lung tissue. Immunofluorescence demonstration of JAM-A in WT and P2X7−/<sup>−</sup> mice (**A**–**D**). Note the increase in immunoreactivity of JAM-A in P2X7−/<sup>−</sup> mice (**B**,**D**). (**C**,**D**) Double immunofluorescence with the AECI marker T1α (TexasRed). Arrows show the linear pattern of JAM-A. Arrowheads depict examples of epithelial junctions. Bar = 100 μm. Corresponding mRNA (**E**) (Wildtype (WT) normalized to 1; *n* = 3; *p*-value 0.5737) and protein (**F**) (*n* = 3, *p*-value 0.0357) levels in lung homogenates. \* *p* < 0.05.

A significant increase in JAM-A protein content was found in the P2X7−/<sup>−</sup> mice. The total mRNA level of JAM-A was also found to be increased.

Immunofluorescence staining confirmed the change in JAM-A expression. WT mice showed a predominantly linear staining pattern of localization for JAM-A. This pattern of immunoreactivity did not change in the P2X7−/<sup>−</sup> mice. Only quantitative alterations were observable. There were no signs of disrupted junctions. Double immunofluorescence experiments with AECI specific T1α revealed a prominent JAM-A localization related to the AECI-AECI and AECI-AECII border.
