HUMAN ORBITAL FIBROBLASTS IN CULTURE EXPRESS GANGLIOSIDE PROFILES DISTINCT FROM THOSE IN DERMAL FIBROBLASTS

Orbital fibroblasts appear phenotypically distinct from those derived from dermis and other extraorbital anatomical sites. In this study, we examined the profile of gangliosides expressed by orbital and dermal fibroblasts. Gangliosides have a wide range of functions including modulation of transmembrane signal transduction. The aim of this study was to examine the hypothesis that a differential expression of gangliosides by orbital and nonorbital fibroblasts could constitute an important determinant of the immunological properties peculiar to the orbit. Moreover, these differences could provide a molecular basis for the site-specific involvement of the orbit in Graves' ophthalmopathy. Total lipids were extracted from confluent cultures of six different orbital and six dermal fibroblast strains, and purified gangliosides were subjected to two-dimensional thin layer chromatographic analysis. Orbital and dermal fibroblasts contained qualitatively similar ganglioside contents, with two major peaks, one migrating in the mono- and the other in the disialoganglioside regions of the chromatogram. In orbital fibroblasts, the densities of these two peaks were nearly equal, whereas in dermal fibroblasts, the monosialoganglioside peak was 5- to 6-fold greater. Minor ganglioside peaks were resolved and were equally abundant in orbital and dermal fibroblasts. Ganglioside profiles were invariant with respect to treatment of fibroblasts with interferon-gamma. These differences in expression of the two major ganglioside species may be relevant to the peculiarities associated with normal and pathological events in orbital connective tissue.