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Meningeal macrophages reflect lymphocytic choriomeningitis virus pathogenic phenotypes
Abstract:
Intracerebral (i.c.) infection of adult mice with lymphocytic choriomeningitis (LCM) virus can result in acute lethal central nervous system (CNS) disease which is the result of the host's thymus-derived lymphocyte (T cell) response against the virus. Whether the specific effector function of the T cell is that of a cytotoxic cell (Tc) or a delayed-type hypersensitivity cell (Td) is still under debate. We assumed that if Td cells were important in pathogenesis then accessory cells in the brain (specifically, glass-adherent macrophages) might vary with the outcome of i.c. infection. We found that accumulation of macrophages in the brain (washed from meninges and skull cap) appeared to be independent of the severity of the infection (controlled by the mouse strain as well as the strain and dose of virus used). However, differentiation of macrophages was clearly linked to whether or not the infection caused rapid death. In mice that were destined to survive, macrophages became large, extensively vacuolated, and phagocytically active. In lethally-infected mice macrophages were small and had poor phagocytic abilities. At present this dichotomy could be viewed as either a cause or a consequence of disease outcome. However, the data are not inconsistent with the hypothesis that Td lymphocytes may be of primary importance in pathogenesis.
Insights
The host's T cell response to lymphocytic choriomeningitis virus (LCMV) causes lethal central nervous system (CNS) disease. Macrophage differentiation in the brain, not accumulation, correlates with survival, suggesting a role for Td lymphocytes in pathogenesis.
Area of Science:
- Neuroimmunology
- Virology
- Immunopathology
Background:
- Intracerebral (i.c.) infection with lymphocytic choriomeningitis virus (LCMV) in adult mice leads to fatal central nervous system (CNS) disease.
- The pathogenesis is attributed to the host's thymus-derived lymphocyte (T cell) response.
- A key debate exists regarding whether cytotoxic T cells (Tc) or delayed-type hypersensitivity T cells (Td) are the primary effectors.
Purpose of the Study:
- To investigate the role of Td lymphocytes in LCMV-induced CNS disease pathogenesis.
- To examine the potential involvement of brain-associated accessory cells, specifically macrophages, in varying infection outcomes.
- To determine if macrophage differentiation correlates with disease severity and survival.
Main Methods:
- Intracerebral inoculation of adult mice with LCMV, utilizing different mouse strains, virus strains, and doses to control infection severity.
- Analysis of macrophage accumulation and differentiation in the brain (meninges and skull cap) of infected mice.
- Correlation of macrophage characteristics with clinical outcomes (survival vs. lethal disease).
Main Results:
- Macrophage accumulation in the brain was independent of infection severity.
- Macrophage differentiation was strongly linked to the outcome of the infection.
- In surviving mice, macrophages were large, vacuolated, and phagocytically active; in lethally infected mice, macrophages were small with poor phagocytic ability.
Conclusions:
- The observed dichotomy in macrophage differentiation suggests a potential role in disease outcome, either as a cause or consequence.
- The findings support the hypothesis that Td lymphocytes may play a primary role in the pathogenesis of LCMV-induced CNS disease.
- Further research is warranted to elucidate the precise mechanisms linking Td cells, macrophages, and CNS disease progression.