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

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 (A-E, G) except the Syk-deficient (Syk^del/del) mice (F, H). Following HDM exposure, increased peribronchial leukocyte recruitment (DAPI staining, blue) was also observed (C,D,G,H), as was an increase in α-smooth muscle actin (stained red); this pattern was observed in the control Veh and Syk^flox/flox mice (C,G) as well as the GSK-treated and Syk-deficient Syk^del/del mice (D,H). Images are representative of 4 mice/group. Bar represents 100 μm. I: 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^flox/flox and Syk^del/del mice, nor between BALB/c mice treated with Veh or GSK143.