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IQGAP2 regulates blood-brain barrier immune dynamics
Ketaki A Katdare1, Andrew Kjar2, Natasha M O'Brown3
1Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA.
Iscience
|March 12, 2025
Summary
The scaffold protein IQGAP2 normally prevents immune cells from entering the brain. Loss of IQGAP2 in brain endothelial cells (BECs) increases immune cell infiltration into the central nervous system (CNS).
Area of Science:
- Neuroimmunology
- Cell Biology
- Vascular Biology
Background:
- Brain endothelial cells (BECs) form the blood-brain barrier (BBB), controlling central nervous system (CNS) homeostasis.
- BECs typically express low adhesion receptors, limiting leukocyte entry, but underlying molecular mechanisms are unclear.
Purpose of the Study:
- To investigate the role of the scaffold protein IQ motif containing GTPase-activating protein 2 (IQGAP2) in regulating immune cell infiltration across the BBB.
Main Methods:
- Utilized mouse and zebrafish models with and without Iqgap2.
- Employed single-cell RNA sequencing and immunohistology on brain endothelial cells.
- Analyzed human hippocampal tissue from Alzheimer's disease patients.
Main Results:
- Loss of Iqgap2 significantly increased peripheral leukocyte infiltration into the CNS in both homeostatic and inflammatory states.
- Iqgap2-deficient BECs displayed a heightened inflammatory profile, with increased adhesion molecules and antigen-processing machinery.
- Reduced hippocampal IQGAP2 levels were observed in Alzheimer's disease.
Conclusions:
- IQGAP2 is a critical regulator of BBB immune privilege.
- IQGAP2 deficiency promotes immune cell entry into the CNS.
- Dysregulation of IQGAP2 may contribute to CNS inflammatory conditions like Alzheimer's disease.
