Figure 1

Attenuated adiponectin signaling in SSc skin biopsies. (a) Left, immunofluorescence using antibodies to phospho-AMP-activated protein kinase (Thr172) (p-AMPK; green) and α-smooth muscle actin (αSMA, red); nuclei stained with DAPI (blue). Skin biopsies from SSc patients (n = 20) and age-matched healthy controls (n = 4) were examined. Dotted lines indicate the border between the epidermis and dermis. Representative photomicrographs; scale bar = 50 µm. Inset illustrating interstitial myofibroblasts within lesional dermis that are p-AMPK negative, scale bar = 10 µm. Right, quantification of p-AMPK-positive cells within the dermis. Results are shown as pAMPK⁺ cells/total nuclei, and p-AMPK/α-SMA double-positive cells/αSMA⁺ cells. Values are means ± SD from three high-power fields in each biopsy. (b) Unsupervised cluster analysis. Heatmap demonstrating altered expression of genes (432) significantly correlated with adiponectin mRNA levels (r > 0.4, p < 0.005) measured in 70 SSc (left) and 20 control (right) skin biopsies. Red (green) color indicates higher (lower) levels of gene expression. Note that 37/70 subjects map to a subset with distinctly differentially regulated expression pattern. (c) Adiponectin signaling scores (described in Methods) were measured in skin biopsy transcriptome dataset (GSE49332). In addition to the significant difference between SSc and controls (red bars, mean ± SD, p = 0.04), note bimodal distribution in SSc, with 41 patients (blue) demonstrating normal adiponectin pathway scores and 29 (green) showing markedly decreased pathway scores. (d) Adiponectin pathway activation scores are significantly correlated with p-AMPK expression.