Pglyrp3/4 Promote Treg and Inhibit Th17 Responses Figure 1. Pglyrp32/2 and Pglyrp42/2 mice have enhanced response in the oxazolone model of atopic dermatitis and Pglyrp12/2 and other Pglyrp2/2 mice have reduced response in the oxazolone model of contact dermatitis. (A) Atopic dermatitis model: sensitization followed by 10 applications of oxazolone to the ears every other day induces mild inflammation (left) and mild ear swelling (right) in WT mice (black triangles) and severe inflammation with increased redness, scaling, and extensive ear swelling in Pglyrp32/2 and Pglyrp42/2 mice (color triangles). (B) Contact dermatitis model: sensitization followed by a single application of oxazolone to the ears induces strong ear swelling in WT mice (black triangles) and reduced ear swelling in Pglyrp12/2, Pglyrp22/2, and Pglyrp42/2 mice (color triangles). Means 6 SEM (SEM were often smaller than the symbols in this and other figures); N = 9–17 mice/group; significance of differences between Pglyrp2/2 and WT mice: *, P,0.02; **, P,0.0001. doi:10.1371/journal.pone.0024961.g001 WT mice Pglyrp1 (and also to some extent Pglyrp2 and Pglyrp4) has an enhancing proinflammatory role in this model of contact dermatitis. Thus, altogether our results indicate that individual PGRPs have selective and distinct effects on skin inflammation. In WT mice Pglyrp3 and Pglyrp4 offer protection in the oxazolone atopic dermatitis model, Pglyrp1 has a pro-inflammatory effect both atopic and contact dermatitis models, and Pglyrp2 has little effect on the atopic dermatitis and has a pro-inflammatory effect in the contact dermatitis model of skin inflammation. Expression of PGRPs in inflamed ears To gain further insight how individual PGRPs influence sensitivity to both models of skin inflammation, we compared expression of all PGRPs in the ears in untreated and oxazolone- treated mice. In both atopic and contact dermatitis models PLoS ONE | www.plosone.org 3 September 2011 | Volume 6 | Issue 9 | e24961