Intravitreal treatment with antisense oligonucleotides targeting tumor necrosis factor-α in murine herpes simplex virus type 1 retinitis

Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine known to participate in intraocular inflammatory disease. This study investigated whether treatment with intravitreal antisense-oligonucleotides (ASON) targeting TNF-alpha mRNA affects the progression of herpes simplex virus 1 (HSV-1) retinitis in mice. The in vivo uptake of the oligonucleotid after intravitreal injection was determined with FITC-labeled TNF-alpha ASON. HSV-retinitis was induced on day 0 by the injection of HSV-1 (KOS strain) into the anterior chamber (AC) of the right eyes of BALB/c mice (von Szily model). The left contralateral eyes were injected intravitreally on day 7 with TNF-alpha ASON, sequence-unspecific control ASON (CON), or buffer. The clinical course of retinitis, ocular inflammatory cell-infiltration, TNF-alpha expression in the eye by ELISA, delayed-type hypersensitivity (DTH) reaction, virus-neutralizing antibody titers in the serum, uptake of [3H]thymidine from regional lymph node (rln) cells, and viral content in the eyes were determined. In vivo, strong fluorescence of FITC- TNF-alpha ASON was detected in the choroid and retina up to 3 days after intravitreal injection, but none in the rln. After treatment of eyes with ASON, decreased expression of TNF-alpha in the eye, and reduced incidence and severity of retinitis on day 10 after infection (P < 0.05) could be found. The other parameters were not significantly influenced after TNF-alpha ASON treatment. TNF-alpha participates in the pathology of HSV-1 retinitis. Local inhibition of TNF-alpha mRNA by intraocular TNF-alpha ASON injection did not influence the systemic HSV-specific immune response or the antiviral response in the eye, but reduced ocular inflammatory bystander damage.