MCP-1 and CCR2 contribute to non-lymphocyte-mediated brain disease induced by Fr98 polytropic retrovirus infection in mice: role for astrocytes in retroviral neuropathogenesis.
Virus infection of the central nervous system (CNS) often results in chemokine upregulation. Although often associated with lymphocyte recruitment, increased chemokine expression is also associated with non-lymphocyte-mediated CNS disease. In these instances, the effect of chemokine upregulation on neurological disease is unclear. In vitro, several chemokines including monocyte chemotactic protein 1 (MCP-1) protect neurons from apoptosis. Therefore, in vivo, chemokine upregulation may be a protective host response to CNS damage. Alternatively, chemokines may contribute to pathogenesis by stimulating intrinsic brain cells or recruiting macrophages to the brain. To investigate these possibilities, we studied a neurovirulent retrovirus, Fr98, that induces severe non-lymphocyte-mediated neurological disease and causes the upregulation of several chemokines that bind to chemokine receptors CCR2 and CCR5. Knockout mice deficient in CCR2 had reduced susceptibility to Fr98 pathogenesis, with significantly fewer mice developing clinical disease than did wild-type controls. In contrast, no reduction in Fr98-induced disease was observed in CCR5 knockout mice. Thus, signaling through CCR2, but not CCR5, plays an important role in Fr98-mediated pathogenesis. Three ligands for CCR2 (MCP-1, MCP-3, and MCP-5) were upregulated during Fr98 infection of the brain. Antibody-blocking experiments demonstrated that MCP-1 was important for retrovirus-induced neurological disease. In situ hybridization analysis revealed that MCP-1 was expressed by glial fibrillary acidic protein-positive astrocytes. Thus, astrocytes, previously not thought to play an effector role in the disease process were found to contribute to pathogenesis through the production of MCP-1. This study also demonstrates that chemokines can mediate pathogenesis in the CNS in the absence of lymphocytic infiltrate and gives credence to the hypothesis that chemokine upregulation is a mechanism by which retroviruses such as human immunodeficiency virus induce neurological damage.
Peterson
Karin E
KE
Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease/NIH, 903 S. 4th Street, Hamilton, MT 59840, USA.
Errett
John S
JS
Wei
Tao
T
Dimcheff
Derek E
DE
Ransohoff
Richard
R
Kuziel
William A
WA
Evans
Leonard
L
Chesebro
Bruce
B
D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000821:virology; D001927:Brain Diseases / Q000503:physiopathology* / Q000821:virology; D018932:Chemokine CCL2 / Q000378:metabolism*; D054410:Chemokine CCL7; D016207:Cytokines; D017353:Gene Deletion; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008214:Lymphocytes / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018945:Monocyte Chemoattractant Proteins / Q000378:metabolism; D054390:Receptors, CCR2; D019707:Receptors, Chemokine / Q000235:genetics / Q000378:metabolism*; D012190:Retroviridae / Q000472:pathogenicity*; D012192:Retroviridae Infections / Q000503:physiopathology* / Q000821:virology; D015854:Up-Regulation; D014774:Virulence; D014779:Virus Replication
C515450:CCL7 protein, human; C515334:CCR2 protein, human; C491224:Ccl12 protein, mouse; C515451:Ccl7 protein, mouse; C515335:Ccr2 protein, mouse; D018932:Chemokine CCL2; D054410:Chemokine CCL7; D016207:Cytokines; D005904:Glial Fibrillary Acidic Protein; D018945:Monocyte Chemoattractant Proteins; D054390:Receptors, CCR2; D019707:Receptors, Chemokine