Cytokine profiles and inflammatory cells during HSV-1-induced acute retinal necrosis.

Purpose: To investigate infiltrating cells, cytokines, and kinetics of cytokine expression during acute retinal necrosis (ARN) in the uninoculated eye after inoculation of herpes simplex virus (HSV)-1 into the anterior chamber of one eye of BALB/c mice.

Methods: At different time points after inoculation of 2 x 10(4) plaque-forming units (PFU) HSV-1 (KOS strain) or an equivalent volume of Vero cell extract in cell culture medium, the uninoculated eyes were enucleated. RT-PCRs for TNFalpha, IFNgamma, and IL-4 and immunohistochemical staining were performed to identify infiltrating cells and cytokines. Cytometric bead array was used to measure the levels of TNFalpha, IFNgamma, and IL-4 protein.

Results: CD4(+) T cells, F4/80(+) macrophages, Gr-1(+) polymorphonuclear cells (PMNs), and CD19(+) B cells were detected in the uninoculated eye of virus-infected mice. Furthermore, RPE65(+) retinal pigment epithelial (RPE) cells and activated Muller cells were also detected in the ARN lesion. TNFalpha, IFNgamma, and IL-4 mRNA and protein were upregulated during the evolution of ARN in HSV-1-infected contralateral eyes compared with levels in control subjects. Immunohistochemistry revealed that cytokines were produced by infiltrating cells as well as by resident retinal cells.

Conclusions: The results of these studies support the idea that T cells and cytokines are actively involved in HSV-1 retinitis. They also suggest that PMNs, B cells, and/or macrophages, as well as resident retinal cells, such as RPE and activated Muller cells, also play a role in the pathogenesis of HSV-1 retinitis.