Prostaglandin E2 elicits a morphological change in cultured orbital fibroblasts from patients with Graves ophthalmopathy.

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Abstract
Fibroblasts derived from distinct anatomical regions appear to differ in regard to their behavior in culture. These differences may reflect functions of these cells in vivo that are tissue specific. Moreover, intrinsic differences in fibroblasts may underlie the site-specific connective tissue manifestations associated with systemic disease. We have demonstrated previously that orbital fibroblasts exhibit different cytokine response domains and protein synthetic programs when compared to those emanating from the skin. In the present communication, we demonstrate that prostaglandin E2 (PGE2) elicits in cultured human orbital fibroblasts from patients with Graves ophthalmopathy a rapid and dramatic change in cell morphology in vitro as assessed by phase-contrast and scanning electron microscopy. The central areas of the cells become elevated with respect to the plane of the substratum and are stellate, with long processes that touch neighboring cells. These changes occur within 6 hr of prostanoid addition to culture medium at an apparent concentration threshold of approximately 10 nM. Shape changes are accompanied by marked alterations in monolayer impedance as assessed by electric cell-substrate impedance sensing as described previously. Both morphologic and impedance changes elicited by PGE2 revert over 24 hr toward those found in untreated cells despite the continued presence of the prostanoid in the culture medium. In contrast, dermal fibroblasts fail to respond to PGE2. These observations define a previously unrecognized phenotypic attribute of orbital fibroblasts. Intrinsic differences in these cells may account for the anatomic site-selective vulnerability of the orbit in Graves ophthalmopathy. The culture system described here may be useful for studying the morphogenic actions of prostanoids.