PURPOSE: To characterize the mechanism of corneal ulceration associated with viral keratitis, the authors investigated the effects of polyinosinic-polycytidylic acid [poly(I:C)], a synthetic analog of viral double-stranded RNA, on the expression of matrix metalloproteinases (MMPs) in human corneal fibroblasts. METHODS: The expression of MMPs in human corneal fibroblasts cultured in the absence or presence of poly(I:C) was examined by immunoblot analysis, gelatin zymography, and quantitative reverse transcription-polymerase chain reaction analysis. The phosphorylation of the NF-κB inhibitor protein IκB-α was assessed by immunoblot analysis, and the concentration of interleukin (IL)-1β in culture supernatants was measured by enzyme-linked immunosorbent assay. RESULTS: Poly(I:C) increased the expression of MMP-1 and MMP-3 in corneal fibroblasts at the mRNA and protein levels. It also induced the phosphorylation of IκB-α and the secretion of IL-1β in these cells. The poly(I:C)-induced expression of MMP-1 and MMP-3 was attenuated by a synthetic inhibitor of NF-κB signaling and by IL-1 receptor antagonist; the latter also inhibited poly(I:C)-induced phosphorylation of IκB-α. CONCLUSIONS: Poly(I:C) induces the expression of MMP-1 and MMP-3 in human corneal fibroblasts in a manner dependent on activation of the transcription factor NF-κB and on IL-1β secretion. These effects may play an important role in corneal ulceration associated with viral keratitis.
PURPOSE: To characterize the mechanism of corneal ulceration associated with viral keratitis, the authors investigated the effects of polyinosinic-polycytidylic acid [poly(I:C)], a synthetic analog of viral double-stranded RNA, on the expression of matrix metalloproteinases (MMPs) in human corneal fibroblasts. METHODS: The expression of MMPs in human corneal fibroblasts cultured in the absence or presence of poly(I:C) was examined by immunoblot analysis, gelatin zymography, and quantitative reverse transcription-polymerase chain reaction analysis. The phosphorylation of the NF-κB inhibitor protein IκB-α was assessed by immunoblot analysis, and the concentration of interleukin (IL)-1β in culture supernatants was measured by enzyme-linked immunosorbent assay. RESULTS:Poly(I:C) increased the expression of MMP-1 and MMP-3 in corneal fibroblasts at the mRNA and protein levels. It also induced the phosphorylation of IκB-α and the secretion of IL-1β in these cells. The poly(I:C)-induced expression of MMP-1 and MMP-3 was attenuated by a synthetic inhibitor of NF-κB signaling and by IL-1 receptor antagonist; the latter also inhibited poly(I:C)-induced phosphorylation of IκB-α. CONCLUSIONS:Poly(I:C) induces the expression of MMP-1 and MMP-3 in human corneal fibroblasts in a manner dependent on activation of the transcription factor NF-κB and on IL-1β secretion. These effects may play an important role in corneal ulceration associated with viral keratitis.