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Updated: Jun 16, 2026
Induction of Experimental Autoimmune Encephalomyelitis in Mice and Evaluation of the Disease-dependent Distribution of Immune Cells in Various Tissues
Published on: May 8, 2016
Minocycline differentially modulates macrophage mediated peripheral immune response following Japanese encephalitis
Kallol Dutta1, Manoj Kumar Mishra, Arshed Nazmi
1National Brain Research Centre, Manesar, Haryana-122050, India.
Abstract:
Japanese encephalitis virus (JEV) is a neurotropic flavivirus that is the causative agent of a major mosquito-borne encephalitis in the world. Evasion of peripheral immune system facilitates the entry of the virus into the central nervous system (CNS) where it causes extensive neuronal inflammatory damage that leads to death or severe neuropschychiatric sequel in survivors. It has been proposed that after entry into the body, the virus is carried into the CNS by peripheral immune cells that act as Trojan horses. In this study we investigate whether macrophages can be considered as such a Trojan horse. We also investigate the role of minocycline, a synthetic tetracycline, in such processes. Minocycline has been found to be broadly protective in neurological disease models featuring inflammation and cell death but there has been no report of it having any modulatory role in peripheral macrophage-mediated immune response against viral infection. Persistence of internalized virus within macrophages was visualized by immunofluorescent staining. Cytotoxicity assay revealed that there was no significant cell death after 24 h and 72 h infection with JEV. Proinflammatory cytokine levels were elevated in cells that were infected with JEV but it was abrogated following minocycline treatment. Reactive oxygen species level was also increased after JEV infection. Nitric oxide level was found to increase after 72 h post infection but remained unchanged after 24h. The cellular levels of signaling molecules such as PI3 kinase, phophoAkt and phospho p38MAP kinase were found to be altered after JEV infection and minocycline treatment. JEV infection also affected the VEGF-MMP pathway. Increased activity of MMP-9 was detected from JEV-infected macrophage culture supernatants after 72 h; minocycline treatment resulted in reduced activity. Thus it seems that minocycline dampens peripheral immune reactions by decreasing proinflammatory cytokine release from infected macrophages and the virus survives within macrophages long enough to be carried into the CNS, even though minocycline inhibits cell survival.
Insights
Minocycline treatment reduces inflammatory responses in macrophages infected with Japanese encephalitis virus (JEV). This suggests JEV may still reach the central nervous system (CNS) despite minocycline
Area of Science:
- Neurovirology
- Immunology
- Pharmacology
Background:
- Japanese encephalitis virus (JEV) causes severe neuroinflammation and neurological damage.
- Peripheral immune cells, like macrophages, may transport JEV into the central nervous system (CNS).
- Minocycline is known for neuroprotection but its role in macrophage-mediated viral transport is unclear.
Purpose of the Study:
- To investigate if macrophages act as 'Trojan horses' for JEV.
- To determine minocycline's effect on JEV-infected macrophages and their immune response.
- To explore minocycline's impact on JEV's potential CNS entry.
Main Methods:
- Macrophage infection with JEV.
- Immunofluorescent staining to visualize viral persistence.
- Cytotoxicity assays to assess cell death.
- Measurement of proinflammatory cytokines, reactive oxygen species, and nitric oxide.
- Analysis of signaling pathways (PI3K, Akt, p38 MAPK) and VEGF-MMP pathway.
- Assay of MMP-9 activity.
Main Results:
- JEV infection did not cause significant macrophage cytotoxicity within 72 hours.
- JEV infection elevated proinflammatory cytokines, reactive oxygen species, and nitric oxide (at 72h).
- Minocycline treatment abrogated elevated cytokine levels and reduced MMP-9 activity.
- JEV infection altered PI3K, Akt, and p38 MAPK signaling pathways, which were modulated by minocycline.
Conclusions:
- Macrophages can harbor JEV, potentially acting as carriers to the CNS.
- Minocycline reduces peripheral inflammatory responses from infected macrophages.
- Despite inhibiting some inflammatory pathways, minocycline may not prevent JEV's CNS entry via macrophages.
