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Published on: October 6, 2023
Central nervous system resilience to cyclophosphamide: preserved behavior, astrocytes and LGALS3 expression in
Rogério Aires1, Alex de Camargo Coque1, Lucas Maruchi Delapena Silva1
1Epigenetic Study Center and Gene Regulation - CEEpiRG, Program in Environmental and Experimental Pathology, Paulista University, São Paulo, São Paulo, 04026-002, Brazil.
Insights
Repeated low-dose cyclophosphamide effectively suppresses the immune system in mice without causing significant central nervous system (CNS) damage or behavioral changes. However, it does increase Lgals3 gene expression in the brain, suggesting an adaptive neuroimmune response.
Area of Science:
- Neuroscience
- Immunology
- Pharmacology
Background:
- Cyclophosphamide is a common immunosuppressant in research.
- Its effects on the central nervous system (CNS) can complicate neuroimmune studies.
- Understanding these CNS effects is crucial for accurate interpretation of experimental results.
Purpose of the Study:
- To investigate the longitudinal effects of repeated cyclophosphamide administration on mouse behavior.
- To analyze molecular and histological changes in the CNS following immunosuppression.
- To determine the impact of cyclophosphamide on neuroimmune interactions in experimental models.
Main Methods:
- Adult male C57BL/6 mice received weekly intraperitoneal injections of cyclophosphamide (100 mg/kg) for 3-4 weeks.
- Immunosuppression was confirmed by monitoring body weight and leukocyte counts.
- Behavioral tests included SHIRPA, open-field, and tail suspension tests.
- CNS integrity was assessed via histopathology, GFAP immunohistochemistry, and Lgals3 gene expression analysis.
Main Results:
- Cyclophosphamide induced sustained immunosuppression and altered leukocyte profiles.
- No significant histopathological changes or astrocytic activation (GFAP) were observed in the brain.
- Mild, transient behavioral changes related to muscle strength and sickness behavior were noted.
- Lgals3 gene expression was significantly upregulated in the brain post-cyclophosphamide treatment.
Conclusions:
- Repeated low-dose cyclophosphamide effectively suppresses peripheral immunity without inducing overt neuroinflammation or major CNS impairment.
- The observed upregulation of Lgals3 suggests a compensatory neuroimmune response, indicating CNS resilience.
- This protocol is suitable for neuroimmune studies, minimizing confounding neurotoxic effects.
Background:
Cyclophosphamide is widely used as an immunosuppressive agent in experimental models. However, its potential effect on central nervous system (CNS) function and behavior may confound studies investigating neuroimmune interactions, interpretation of results, and translational relevance.
Objectives:
To characterize longitudinal behavioral outcomes and CNS-related molecular and histological changes following repeated cyclophosphamide-induced immunosuppression in mice.
Methods:
Adult male C57BL/6 mice received an intraperitoneal injection of cyclophosphamide (100 mg/kg) for three or four consecutive weeks. Peripheral immunosuppression was assessed by body weight monitoring and leukocyte differential counts. Behavioral performance was evaluated longitudinally using the SHIRPA protocol, open-field test, and tail suspension test (TST). CNS integrity was analyzed through histopathology, GFAP immunohistochemistry, and quantitative PCR analysis of Lgals3 in brain tissue.
Results:
Cyclophosphamide administration induced a sustained reduction in body weight gain and significant alterations in leukocyte profile, confirming immunosuppression. Behavioral assessment did not demonstrate significant changes, only mild and transient ones, mainly related to muscle strength and subtle sickness-like behavior. No histopathological alterations or astrocytic activation were detected in brain tissue, as GFAP immunoreactivity remained unchanged across experimental groups. Lgals3 gene expression was significantly upregulated in the brains of immunosuppressed animals following both three and four cycles.
Conclusion:
Repeated low-dose cyclophosphamide administration induces effective peripheral immunosuppression without causing overt neuroinflammation or major impairment, indicating CNS resilience under these experimental conditions. The upregulated Lgals3 expression suggests an adaptive neuroimmune response that may contribute to maintaining CNS homeostasis during systemic immune dysregulation. These findings support the use of this immunosuppressive protocol in experimental models targeting CNS infections or neuroimmune mechanisms while minimizing confounding neurotoxic effects.
