Abstract
Purpose::
TGFß is a pleiotropic molecule that regulates proliferation and differentiation of a broad spectrum of cell types. TGF-ß release by human bronchial epithelial cells has been described to be enhanced by Th-2 derived cytokines. TGF-ß expression is increased in several inflammatory, proliferative, and degenerative ocular pathologies. Specifically, this factor has been described to be increased in the conjunctival epithelium of vernal keratoconjunctivitis patients, although its origin has not been established. It has also been described that this factor can stimulate human corneal epithelial cells to secrete metalloproteinases involved in ocular surface diseases. The aim of this work was to determine if human conjunctival epithelial cells, in basal and inflammatory conditions: 1) express TGF-ß receptors and 2) secrete TGF-ß.
Methods::
IOBA-NHC (normal human conjunctival) epithelial cell line was used. Cells were exposed to Th1- (TNF-α and IFN-γ) or Th2- (IL-4 and IL-13) derived cytokines for 48h. Unstimulated cells were kept as control. TGF-ß receptors (TGF-ß RI and RII) expression was studied by Western blot (in cell lysates) or by immunofluorescence (in fixed cells). Additionally, TGF-ß1 and -ß2 secretion was measured in cell culture supernatants by ELISA.
Results::
TGF-ß RI and RII expression was detected in unstimulated IOBA-NHC cells. TGF-ß RI expression under TNF-α, IFN-γ, IL-4, and IL-13 treatment was not significantly different from basal expression . TGF-ß RII was immunodetected in cell membrane and in cell cytosol. TGF-ß1, but not TGF-ß2, was basally secreted by IOBA-NHC cells. This secretion was not significantly modified by cytokine treatment.
Conclusions::
Conjunctival epithelial cells express TGF-ß receptors and secrete TGF-ß1, suggesting a potential role in the pathogenesis of certain ocular pathologies.
Keywords: conjunctiva • inflammation • growth factors/growth factor receptors