Microglial Activation in Tuberous Sclerosis Complex: Altered Calcium Signaling and Function

Overview

This study demonstrates that microglia in tuberous sclerosis complex (TSC) exhibit dysregulated calcium signaling, increased metabolic activity, and enhanced phagocytic function. Using patient-derived induced pluripotent stem cell microglia-like cells and transcriptomic analyses of TSC brain tissue, the findings reveal a hyperresponsive microglial phenotype linked to mTOR pathway hyperactivation.

Background

Tuberous sclerosis complex is a genetic disorder characterized by benign tumors and cortical tubers in the brain, often leading to epilepsy and neuropsychiatric manifestations. Mutations in TSC1 or TSC2 genes cause hyperactivation of the mTORC1 pathway, disrupting cellular growth and metabolism. Microglia, the CNS immune cells, play a critical role in maintaining brain homeostasis and are implicated in epilepsy and cognitive deficits in TSC. Calcium signaling in microglia is essential for their functions, but its dysregulation in TSC microglia has not been fully explored until now.

Data Highlights

Key Findings

• Transcriptomic profiling of TSC brain tissue revealed evidence of calcium signaling dysregulation in microglia.
• Patient-derived iPSC microglia-like cells from TSC patients showed increased calcium signaling abnormalities compared to controls.
• TSC microglia exhibited elevated mitochondrial respiration, indicating increased metabolic activity.
• Phagocytic activity was enhanced in TSC iPSC-derived microglia, suggesting a hyperactive immune state.
• The microglial phenotype in TSC resembled stage 2 disease-associated microglia observed in neurodegenerative diseases.

Clinical Implications

These findings suggest that microglial calcium signaling and metabolic dysregulation contribute to the neuropathology of TSC, potentially influencing epilepsy and neuropsychiatric symptoms. Targeting microglial activation and calcium homeostasis may represent a novel therapeutic avenue to modulate neuroinflammation and improve clinical outcomes in TSC patients.

Conclusion

Microglia in tuberous sclerosis complex display a hyperactive state characterized by calcium signaling abnormalities, increased metabolism, and enhanced phagocytosis. This altered microglial function likely contributes to TSC neuropathology and offers new insights for therapeutic intervention.

References

1. Original Article -- Microglial Activation in Tuberous Sclerosis Complex: Increased Calcium Signaling, Metabolic Activity, and Phagocytic Function