Human ocular-derived virus-specific CD4+ T cells control varicella zoster virus replication in human retinal pigment epithelial cells

PURPOSE

Varicella zoster virus (VZV)-induced retinitis is characterized by the presence of virus-infected cells in the retinal layer and the ocular infiltration of VZV-specific T cells. Herein, the susceptibility of human retinal pigment epithelial (RPE) cells to VZV infection and the ability of virus-specific CD4(+) T cells to control VZV infection in RPE cells in vitro is addressed.

METHODS

Human primary RPE cell cultures (n=2) were infected with a VZV strain expressing green fluorescent protein. The infection and viability of infected RPE cells was monitored by flow cytometry or by a fluorescent imager on RPE monolayers. RPE cells, pretreated with or without interferon-gamma (IFN-gamma), were infected with VZV and subsequently cultured with VZV-specific CD4(+) T-cell clones (TCCs; n=3) recognizing disparate VZV proteins presented by different HLA class II alleles. IFN-gamma production and cytotoxicity of the TCCs in response to VZV-infected RPE cells was determined by flow cytometry.

RESULTS

Human RPE cells are permissive to a productive VZV infection. VZV-infected RPE cells presented the cognate antigen to the CD4(+) TCCs only if the RPE cells were pretreated with IFN-gamma and expressed the appropriate HLA class II allele. VZV-specific TCCs inhibited productive VZV infection in RPE cells, which was in part attributed to TCC-mediated killing of the VZV-infected RPE cells.

CONCLUSIONS

The results presented suggest that RPE cells may play a role as retina-resident antigen-presenting cells in the intraocular, VZV-specific, T cell-mediated inflammatory response of VZV-induced uveitis.

Identification of viral antigens recognized by ocular infiltrating T cells from patients with varicella zoster virus-induced uveitis

PURPOSE

Varicella zoster virus (VZV) is a common cause of infectious uveitis associated with an intraocular inflammatory response involving virus-specific T cells. In the current study, the functional characteristics and the antigen specificity of VZV-reactive T cells recovered from intraocular fluid (IOF) samples of five patients with VZV were determined.

METHODS

B-cell lines were infected with a comprehensive panel of recombinant vaccinia viruses expressing 11 individual VZV open reading frames (ORFs), or alternatively pulsed with the corresponding peptides to generate antigen-presenting cells (APCs). T-cell responsiveness of the IOF-derived VZV-specific T cells toward APCs was monitored by interferon (IFN)-gamma enzyme-linked immunosorbent spot-forming assays on bulk T-cell cultures and subsequently T-cell clones (TCCs). The cytokine-secretion profile and cytotoxicity of the VZV-specific TCCs was determined by ELISA and flow cytometry, respectively.

RESULTS

T-cell reactivity to VZV proteins encoded by ORF4, -10, -14, -18, -29, -31, -61, -62, -63, -67, and -68 was demonstrated, but specificity varied individually. T-cell epitopes on ORF62 and -68 were delineated. The TCCs secreted IFNgamma, but relatively low levels of interleukin-4 and -5, in response to VZV antigen-expressing APCs. The TCCs induced antigen-specific cytotoxic T-cell activity.

CONCLUSIONS

The results suggest that the intraocular VZV-specific T-cell response in the patients with VZV analyzed is directed to a broad spectrum of VZV antigens, including the latency-associated VZV proteins from ORFs 4, 29, 63, and particularly ORF62. This local T-cell response was in part mediated by cytotoxic CD4(+) T cells with a Th1/0-like effector memory phenotype.

Characterization of the varicella zoster virus (VZV)-specific intra-ocular T-cell response in patients with VZV-induced uveitis

Varicella zoster virus (VZV) is a well-known cause of infectious uveitis. The aim of this study was to characterize the VZV-specific T-cell response in eyes of patients with VZV-induced uveitis. T-cell lines (TCL) were generated by mitogenic stimulation of intra-ocular fluid (IOF) samples obtained from eight patients with VZV-induced uveitis. Two patients with herpes simplex virus (HSV)-induced uveitis were included as disease controls. Characterization of individual T-cells in the TCL was performed by stimulating the TCL with mock, HSV-1 and VZV antigen pulsed autologous B cells and subsequent flow cytometric analyses. Virus specificity and phenotype of the T-cells were identified by simultaneous detection of intracellular gamma interferon and cell surface markers CD4, CD8, CD3 or T-cell receptor (TCR) beta chain variable region (TCRBV) usage. The TCL obtained from patients with HSV-1-induced uveitis contained higher numbers of T-cells reactive to HSV-1 compared to VZV. VZV-specific T-cells were detected in all TCL of the patients diagnosed with VZV-induced uveitis. Four out of six TCL obtained from patients with VZV-induced uveitis that were assayed for both viruses, contained higher numbers of T-cells reactive to VZV compared to HSV-1. Detailed analyses of the TCL of two patients demonstrated that the VZV reactivity within the assayed TCL was dominated by T-cells expressing one specific TCRBV gene. The data implicate that VZV-reactive T-cells infiltrate and participate in the local inflammatory response in eyes of patients with VZV-induced uveitis.