Figure 4.
Effects of Sirt3 or Pgc1α deletion on Treg function. A) Lack of Sirt3 protein expression in Sirt3−/− Tregs. B) Comparison of Sirt3−/− and WT Treg showed that Sirt3−/− Tregs had reduced ability to suppress the proliferation of WT Tcon cells in vitro; percentage of CFSE-labeled proliferating Tcon cells is shown. C) Pooled data from 3 independent Treg suppression assays, alone or after Treg treatment with an HDAC inhibitor (SAHA). D) Pooled data from 3 independent Treg suppression assays comparing WT and fl-Pgc1α/Foxp3cre Treg suppressive function showed no differences in vitro. E) B6/Rag1−/− cardiac allograft recipients were adoptively transferred with Tcon cells plus WT or fl-Pgc1α/Foxp3cre Tregs at a 2:1 ratio; P value indicates Mantel-Cox. Use of Pgc1α−/− Tregs led to a significant reduction in allograft survival (n = 4 per group). F) Modest impairment of allograft survival with Sirt3−/− Tregs (n = 6 Sirt3−/− and n = 3 control Treg recipients). G) Compared to grafts from mice receiving WT Tregs, hearts still beating at 100 days after transplantation in mice receiving Sirt3−/− Tregs had increased inflammation, fibrosis, and T cell infiltration (scale bar = 100 μm). H and I) Quantification of hematoxylin and eosin (H) and trichrome (I) data show a trend to more severe inflammation, tissue injury, and fibrosis in recipients of Sirt3−/− Tregs. J) qPCR showed a trend to increased INF-γ production in recipients of Sirt3−/− Tregs. H–J) Data were normalized to native Balb/c hearts. *P < 0.05, **P < 0.01.