Fig. 3.

Keratinocyte proliferation is increased by thyroxine (T4) and cytokeratin 6 (CK6) protein expression was reduced under “pathological” conditions and upregulated when T4 was added to the medium. a Double-immunofluorescent Ki-67/TUNEL/DAPI staining showing right wound edges and epidermal tongues (ETs). Statistical analyses of the amount of proliferative/apoptotic cells comparing standard versus (vs.) standard + T4 conditions and “pathological” vs. “pathological” + T4 conditions. Results of proliferative and apoptotic cells are provided as percentage of all cells (number of DAPI-positive cells was set as 100%) inside the reference area from the ETs. b The amount of proliferative cells tended to be increased under standard + T4 medium conditions but was only significant inside the ETs of “pathological” + T4 medium conditions. Apoptosis was reduced under T4-treated medium conditions most significantly under “pathological” medium conditions. ***p ≤ 0.001, **p ≤ 0.01, *p < 0.05; pooled data from three different patients, six punches, 24–35 skin sections; mean ± SEM; p value was calculated by Mann–Whitney U test for unpaired samples. Scale bar: 50 μm. c Immunofluorescent CK6 staining of skin sections showing right wound edges and ETs. Green fluorescent immunoreactivity (IR) represents the CK6-positive signal and appears brighter in the skin from T4-supplemented medium conditions. The CK6-positive IR was assessed in the ETs (yellow continuous line) by quantitative immunofluorescence morphometry. d Statistical analyses demonstrate the assessment of the CK6 IR comparing standard versus (vs.) standard + T4 conditions and “pathological” vs. “pathological” + T4 conditions. All results were normalised to the standard medium (= 100%). Upregulation of CK6 IR was significant under “pathological” conditions. ***p ≤ 0.001; pooled data from three different patients, six punches, 34–35 skin sections; mean ± SEM; p value was calculated by Mann–Whitney U test for unpaired samples. Scale bar: 50 μm