Skin biopsies demonstrate site-specific endothelial activation in mouse models of sepsis.

Skin biopsies allow for direct phenotyping of the endothelium in clinical settings. We hypothesize that in murine sepsis endothelial activation is manifested by changes in protein and mRNA expression in skin biopsies, and that such alterations differ from other organs. In two mouse models of sepsis [endotoxemia and cecal ligation puncture (CLP)], we measured circulating levels of endothelial biomarkers, quantitated mRNA expression of activation markers and assayed for protein expression using immunohistochemistry. Endotoxemic mice demonstrated increased circulating levels of sE-selectin, sICAM-1, sVCAM-1 and sP-selectin at 24 h, while CLP was associated with increased levels of sE-selectin alone. In real-time PCR, mRNA levels for P-selectin, ICAM-1 and PAI-1 were increased in skin from endotoxemic mice. In CLP, mRNA levels for P-selectin, ICAM-1, E-selectin and PAI-1 were elevated, while VCAM-1 expression was reduced in skin. Most, but not all of these changes correlated with alterations in immunohistochemical staining. Expression patterns in skin differed from those in brain, heart, and lung. Skin biopsies demonstrated endothelial cell activation during sepsis. The expression patterns differed by type of sepsis model and between vascular beds of skin, brain, heart, and lung, providing a foundation for identifying skin microvascular-bed-specific molecule signatures.