Adenovirus keratitis: A role for interleukin-8

Purpose. Adenovirus type 19 (Ad19) infection of the human cornea results in a chronic, multifocal, subepithelial keratitis. Existing evidence suggests that early subepithelial corneal infiltrates are composed of polymorphonuc lear neutrophils. In this study, the capacity of Ad13-infected human cornea l stromal fibroblasts (HCFs) to produce neutrophil chemotactants (chemokine s) was tested. Methods. HCFs grown from human donor corneas and passaged thrice were infec ted with a corneal isolate of Ad19 or mock-infected with virus-free media. Bioactivity of the cell supernatants was tested by a neutrophil chemotaxis assay. Supernatants were assayed by enzyme-linked immunosorbent assay for t he neutrophil chemotactants interleukin-8 (IL-8) and GRO-alpha. Corneal fac similes were generated with HCFs and collagen type I, infected with Ad19, a nd assayed by immunohistochemistry. Results. Ad19 infection of HCFs increased neutrophil chemotaxis from a base line of 0.4 +/-. 0.7 cells/high-powered field (hpf; mock-infected) to 21.8 +/- 2.3 cells/hpf (Ad13-infected). Chemotaxis was reduced by the addition o f neutralizing antibodies against IL-8 and GRO-alpha. Infection of HCFs ind uced quantities of IL-8 protein 300- and 1000-fold over mock-infected contr ols at 4 and 24 hours, respectively (33 versus 11,813 pg/mL at 4 hours, and 57 versus 76,376 pg/mL at 24 hours, P less than or equal to 0.001 for both ). In contrast, GRO-alpha protein levels were only sevenfold higher at 24 h ours postinfection (118 pg/mL in mock-infected controls versus 880 pg/mL in Ad19-infected cell supernatants). Neither chemokine was induced by infecti on of an immortalized human corneal epithelial cell line. Immunohistochemis try of infected corneal facsimiles demonstrated IL-8 in the extracellular m atrix within 3 days after infection. Conclusions. Production of chemokines in infected tissues facilitates an ea rly innate immune response to infection, and in the infected corneal stroma represents an elementary defense mechanism. Interleukin-8 may play a role in the development of subepithelial infiltrates in adenovirus keratitis.