Loss of Syk activity does not attenuate airway inflammation and remodeling or total lung collagen content in the chronic HDM-challenge model.

<p>Immunostaining for Syk (green) revealed expression in airway epithelia (arrow) and leukocytes (*) under basal Saline conditions and following HDM exposure in all groups of mice (<b>A-E, G</b>) except the Syk-deficient (Syk<sup>del/del</sup>) mice (<b>F, H</b>). Following HDM exposure, increased peribronchial leukocyte recruitment (DAPI staining, blue) was also observed (<b>C,D,G,H</b>), as was an increase in α-smooth muscle actin (stained red); this pattern was observed in the control Veh and Syk<sup>flox/flox</sup> mice (<b>C,G</b>) as well as the GSK-treated and Syk-deficient Syk<sup>del/del</sup> mice (<b>D,H</b>). Images are representative of 4 mice/group. Bar represents 100 μm. <b>I:</b> Quantitative analysis revealed a 2-fold increase in the total lung collagen content in the HDM mice when compared with Saline control in all groups of mice (*p<0.05, HDM vs. Saline, 2 way ANOVA, n = 4/group). No differences were observed between Syk<sup>flox/flox</sup> and Syk<sup>del/del</sup> mice, nor between BALB/c mice treated with Veh or GSK143.</p>