Microglial SWELL1 deficiency drives male-specific seizure vulnerability but paradoxical neuroprotection through impaired phagocytosis
Abhijeet S. Barath, Aastha Dheer, Laura Montier, Mekenzie M Peshoff, Emily Dale, Flavia Goche, Thanh Thanh Le Nguyen, Mastura Akter, FangFang Qi, Dimitrios Kleidonas, Lauren Harris, Sarah A. Jewanee, Anthony D. Umpierre, Dale B. Bosco, Koichiro Haruwaka, Rajan Sah, Long-Jun Wu
Abhijeet S. Barath, Aastha Dheer, Laura Montier, Mekenzie M Peshoff, Emily Dale, Flavia Goche, Thanh Thanh Le Nguyen, Mastura Akter, FangFang Qi, Dimitrios Kleidonas, Lauren Harris, Sarah A. Jewanee, Anthony D. Umpierre, Dale B. Bosco, Koichiro Haruwaka, Rajan Sah, Long-Jun Wu
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Research Article Immunology Neuroscience

Microglial SWELL1 deficiency drives male-specific seizure vulnerability but paradoxical neuroprotection through impaired phagocytosis

Abstract

The discovery of genes encoding the volume-regulated anion channel (VRAC) has enabled detailed exploration of its cell type–specific roles in the brain. LRRC8A (SWELL1) is the essential VRAC subunit. We observed seizure-induced, subunit-specific changes in microglial VRAC expression and investigated its function using conditional KO (cKO) of LRRC8A in microglia. SWELL1 cKO mice exhibited a male-specific increase in kainate-induced seizure severity, yet showed paradoxical neuroprotection against seizure-associated neuronal loss. Mechanistically, SWELL1 deletion led to a cell-autonomous reduction in microglial density and decreased release of VRAC-permeable neuroactive metabolites, including taurine, GABA, and glutamate in culture. Additionally, impaired phagocytic kinetics and reduced lysosomal biogenesis contributed to the observed neuroprotection. These findings reveal potentially novel roles for microglial VRAC in regulating seizure outcomes and microglia-neuron interactions.

Authors

Abhijeet S. Barath, Aastha Dheer, Laura Montier, Mekenzie M Peshoff, Emily Dale, Flavia Goche, Thanh Thanh Le Nguyen, Mastura Akter, FangFang Qi, Dimitrios Kleidonas, Lauren Harris, Sarah A. Jewanee, Anthony D. Umpierre, Dale B. Bosco, Koichiro Haruwaka, Rajan Sah, Long-Jun Wu

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Figure 6

Female SWELL1 cKO mice exhibit neuroprotection without increased seizure severity.

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Female SWELL1 cKO mice exhibit neuroprotection without increased seizure...
(A) Longitudinal Racine seizure scores in SWELL1 cKO versus littermate (LM) controls. (n = 15–24 mice/group; statistic: 2-way ANOVA). (B) Survival rate. (C) Microglia density in cortex at 4–6 weeks after the last tamoxifen/vehicle administration (6–8 animals/group examined). Scale bar: 50 μm. (D) Quantification of microglia density in cortex and CA3 (statistic: unpaired t test and Mann-Whitney U test, respectively). (E) Nissl staining showing neuronal loss in CA3 pyramidal layer at day 3 after seizure (7–8 animals/group examined). Scale bar: 50 μm. (F) Quantification of Nissl-positive cell bodies at day 3 after seizure (statistic: unpaired t test). (G) Immunofluorescence images showing neuronal loss and myeloid and CD68 responses in CA3 at day 3 after seizure (8–9 animals/group examined). Scale bar: 50 μm. (H and I) Quantification of myeloid cell density and Iba1+ area in CA3 pyramidal layer at day 3 after seizure (statistic: unpaired t tests). (J and K) Quantification of CD68+ area and mean granule size in CA3 at day 3 after seizures (statistic: unpaired t tests). (L) Quantification of NeuN-CD68 double-positive voxels in CA3 pyramidal layer (statistic: unpaired t test). (M) Correlation between CD68+ and NeuN+ area in CA3 pyramidal layer at day 3 after seizure (statistic: Pearson’s correlation coefficient). (N) Quantification of Iba1-CD68 double-positive voxels in CA3 pyramidal layer as a percentage of Iba1+ volume (statistic: unpaired 2-tailed t test). (O) Correlation between Iba1+ and CD68+ area in CA3 pyramidal layer at day 3 after seizure (statistic: Pearson’s correlation coefficient; simple linear regression to compare the slopes). *P < 0.05.