Topical treatment with antisense oligonucleotides targeting tumor necrosis factor-alpha in herpetic stromal keratitis

Tumor necrosis factor (TNF)-alpha is a pleiotropic factor that is critical for the development of inflammation. The authors investigated whether topical application of TNF-alpha-antagonizing molecules, antisense oligonucleotides (ASON), might be an effective way of modifying the course of immune-mediated herpetic stromal keratitis (HSK).

ASON targeting TNF-alpha mRNA were examined for their efficiency in interfering with the production of this cytokine in vitro. In vivo uptake was determined by FITC-labeled ASON. HSV-1 corneally infected mice were injected three times with ASON. Mice from the control groups received unrelated control oligonucleotides (CON) or buffer. The clinical course of HSK, the delayed-type hypersensitivity (DTH) reaction, the uptake of [(3)H]thymidine from cells derived from the spleen, virus-neutralizing antibody titers in the serum, and viral replication in the infected eyes were determined. The eyes were examined histologically. The corneal TNF-alpha content was measured by ELISA.

The TNF-alpha ASON reduced the lymphocytic cytokine expression in vitro. In vivo, the FITC-labeled molecules were detected in the cornea even after 10 days. In the TNF-alpha ASON mice the incidence of HSK decreased, and the severity of the disease was diminished. The corneal content of TNF-alpha was reduced, and the number of inflammatory cells was decreased. The other investigated parameters were not significantly altered by TNF-alpha ASON treatment.

The data suggest that TNF-alpha ASON diminishes the release of TNF-alpha from cultured lymphocytes and from lymphocytes in the HSV-1-infected cornea. This topical treatment mitigates the course of HSK, whereas the systemic antiviral effector functions were not impaired.