Figure 6

Blockage of IL-13Rα ₂ prevents TGF-β ₁ production and fibrosis in allogeneically transplanted grafts. (A) Flow cytometric analysis of graft-infiltrating cells of allogeneically (FVB into DBA/1) transplanted hearts (day 100) detected a strongly diminished percentage of CD11b^highGr1^intermediateTGF-β₁ ⁺ cells (0.3%) in the siRNA-treated group compared to the control animals (4.2%). (B) Quantification of collagen by Sircol assay showed significantly less collagen levels in mice injected with specific IL-13Rα₂ siRNA (P = 0.0018) than mice treated with control siRNA. Levels were not significantly different to FVB control hearts (P = 0.1309). (C) Representative Masson’s trichrome stainings showed reduced levels of collagen in allogeneically (FVB into DBA/1) transplanted hearts treated with siRNA compared to mice treated with control peptide (day 100 after transplantation; 20x magnification). (D) In flow cytometric analysis the frequency of CD4⁺Foxp3⁺ Tregs isolated from allogeneically transplanted grafts (day 100) was similar in siRNA- and control siRNA-injected animals (15.6 versus 15.2%). (E) Representative immunohistochemical stainings (day 100) showed numbers of CD4⁺, CD8⁺, and CD11b⁺ cells in FVB allografts transplanted into DBA/1 mice and treated with siRNA that were lower than mice treated with control siRNA and comparable to syngeneic control grafts (Figure  1 A,B,C). At least five mice per group were analyzed. *P <0.05. Treg, regulatory T cell.