Human T-cell lymphotropic virus type 1 can infect primary rat retinal glial cells and induce gene expression of inflammatory cytokines.
OBJECTIVE
To examine whether or not retinal glial cells can be infected by human T-cell lymphotropic virus type 1 (HTLV-1) and test the possibility that HTLV-1-infected retinal glial cells are involved in the pathogenesis of HTLV-1 uveitis (HU).


METHODS
We tested infection of HTLV-1 by a standard coculturing method using WKAH rat retinal glial cells and irradiated MT-2, a human T cell line that produces HTLV-1. Infection was confirmed by detecting the integrated HTLV-1 provirus, using polymerase chain reaction (PCR), viral gene expression, using reverse transcriptase-PCR (RT-PCR) and HTLV-1 p19 ELISA, and by identifying the HTLV-1-infected glial cells by immunofluorescence cytochemistry and in situ hybridization. Changes in cytokine gene expression were studied by RT-PCR.


RESULTS
Using a semiquantitative PCR of HTLV-1 provirus sequence, we found that 2.6% of the retinal glial cells were infected at 3 days after infection, followed by a gradual decrease in the percentage with an extended period of culture up to 4 weeks. This time course of infection was also verified by RT-PCR and ELISA studies that detect viral mRNA expression and protein production, respectively. Expression of HTLV-1 gag protein and tax mRNA was detected in a part of glial cells by indirect immunofluorescence cytochemistry and in situ hybridization, respectively. RT-PCR analysis of cytokine gene expression revealed that gene expression of IL-6, CINC-1 (Gro, KC), and TNF-alpha were induced in these cells, with a peak at 3 weeks after infection.


CONCLUSIONS
These results provided supportive evidence for the theory that the infection of retinal glial cells by HTLV-1 and subsequent production of inflammatory cytokines could be one contributing factor for the development of the unique clinical features of HU. A better understanding of the specific roles of the inflammatory cytokines in the pathogenesis of HU would be beneficial in the treatment and control of this disease.
Sato
Y
Y
Department of Pathology, Faculty of Medicine, University of Tokyo, Japan.
Ito
K
K
Moritoyo
T
T
Fujino
Y
Y
Masuda
K
K
Yamaguchi
K
K
Mochizuki
M
M
Izumo
S
S
Osame
M
M
Watanabe
T
T
D000818:Animals; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D017931:DNA Primers / Q000737:chemistry; D004279:DNA, Viral / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D015967:Gene Expression Regulation, Viral; D015683:Gene Products, gag / Q000096:biosynthesis / Q000235:genetics; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D017403:In Situ Hybridization; D009457:Neuroglia / Q000378:metabolism / Q000821:virology*; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000166:cytology / Q000378:metabolism / Q000821:virology*; D015682:Retroviridae Proteins, Oncogenic / Q000096:biosynthesis / Q000235:genetics; D013601:T-Lymphocytes / Q000821:virology; D054301:gag Gene Products, Human Immunodeficiency Virus
D016207:Cytokines; D017931:DNA Primers; D004279:DNA, Viral; D015683:Gene Products, gag; D012367:RNA, Viral; D015682:Retroviridae Proteins, Oncogenic; D054301:gag Gene Products, Human Immunodeficiency Virus; C060955:p19 protein, Human T-lymphotropic virus 1