Fig. 3

Systemic human C-peptide supplementation simultaneously inhibits HGM-induced TGase activation in the retina, lung, and kidney of HGM mice. C57BL/6 diabetic mice were treated for 4 weeks with insulin (HGM), insulin and K8 polypeptide (HGM + K8), or insulin and K9-C-peptide (HGM + K9-C-pep). Normal, non-supplemented diabetic, and HGM mice underwent sham operations as controls. In vivo TGase activity was visualized in the retina, lung, and kidney by confocal microscopy. A Representative fluorescence images of TGase activity. Scale bar, 50 µm. Quantification of TGase activity in the retina (B), lung (C), and kidney (D) sections based on fluorescence intensity (n = 6). Statistical significance was determined by one-way ANOVA with Holm-Sidak’s multiple comparisons test. **P < 0.01, ***P < 0.001. NS, non-significant