Cytokine gene expression and protein production in West Nile virus‐infected retinal pigment epithelium

Abstract

PurposeTo identify key genes differentially expressed in the human retinal pigment epithelium (hRPE) following low-level West Nile virus (WNV) infection.MethodsPrimary hRPE and retinal pigment epithelium cell line (ARPE-19) cells were infected with WNV (multiplicity of infection 1). RNA extracted from mock-infected and WNV-infected cells was assessed for differential expression of genes using Affymetrix microarray. Quantitative real-time PCR analysis of 23 genes was used to validate the microarray results.ResultsFunctional annotation clustering of the microarray data showed that gene clusters involved in immune and antiviral responses ranked highly, involving genes such as chemokine (C-C motif) ligand 2 (CCL2), chemokine (C-C motif) ligand 5 (CCL5), chemokine (C-X-C motif) ligand 10 (CXCL10), and toll like receptor 3 (TLR3). In conjunction with the quantitative real-time PCR analysis, other novel genes regulated by WNV infection included indoleamine 2,3-dioxygenase (IDO1), genes involved in the transforming growth factor–β pathway (bone morphogenetic protein and activin membrane-bound inhibitor homolog [BAMBI] and activating transcription factor 3 [ATF3]), and genes involved in apoptosis (tumor necrosis factor receptor superfamily, member 10d [TNFRSF10D]). WNV-infected RPE did not produce any interferon-γ, suggesting that IDO1 is induced by other soluble factors, by the virus alone, or both.ConclusionsLow-level WNV infection of hRPE cells induced expression of genes that are typically associated with the host cell response to virus infection. We also identified other genes, including IDO1 and BAMBI, that may influence the RPE and therefore outer blood-retinal barrier integrity during ocular infection and inflammation, or are associated with degeneration, as seen for example in aging.

IRF-3, IRF-5, and IRF-7 Coordinately Regulate the Type I IFN Response in Myeloid Dendritic Cells Downstream of MAVS Signaling

“…Some of the genes we identified in mDCs also were detected in microarray analyses of WNV-infected MEFs [46], human kidney epithelial cells [48], or human retinal pigmented epithelium [47]. Induction of these genes (e.g., Rsad2 , Ifit2 , Isg15 , Isg20 , and Stat1 ) thus does not depend on cell type-specific transcription factors.…”

Role of indoleamine 2,3-dioxygenase in health and disease

“…An increasing number of studies report that infection of cells in vitro with virus alone induces IDO1 expression and activity. For example, IDO1 induction has been reported in human monocyte-derived macrophages infected with HIV [522], the flaviviruses West Nile virus and Japanese encephalitis virus [108,523] and Epstein-Barr virus [94], in human pigment retinal epithelial cells infected with West Nile virus [523], and influenza virus-infected primary human airway epithelial cells [81,524] and a mouse lung epithelial cell line [81].…”

Death Receptor-Mediated Apoptotic Signaling Is Activated in the Brain following Infection with West Nile Virus in the Absence of a Peripheral Immune Response

“…Prior gene expression studies have also identified DR-associated genes that are differentially regulated following WNV infection. For example, (i) Daxx is upregulated in the spleens of mice infected with neuroinvasive strains of WNV compared to noninvasive strains (23); (ii) the death receptor-associated genes encoding cIAP2, TRAIL, TNF, and TRAF1 are upregulated in WNV-infected human retinal pigment epithelium (24), and (iii) multiple pathways involved in apoptosis, including induction of apoptosis by HIV-1, were identified in the brains of horses with exposure to WNV (25). In addition, we previously performed microarray analysis on RNA extracted from the brains of reovirus-infected mice (26).…”