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 2

Transient microglial loss and morphological remodeling in SWELL1 cKO mice.

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Transient microglial loss and morphological remodeling in SWELL1 cKO mic...
(A) Microglia density in CA3 pyramidal layer of hippocampus at various time points after the last tamoxifen/vehicle administration (4–10 animals/group/time point examined). Scale bar: 50 μm. (B) Microglia density in cortex at various time points after the last tamoxifen/vehicle administration (8–10 animals/group/time point examined). Scale bar: 50 μm. (C) Quantification of microglia density in CA3 pyramidal layer (statistic: unpaired t test or Mann-Whitney U test). (D) Quantification of microglia density in cortex (statistic: unpaired 2-tailed t test). (E) Quantification of Iba1+ area in CA3 pyramidal layer (statistic: unpaired 2-tailed t test). (F) Quantification of microglia territory in CA3 pyramidal layer (dot, individual microglia; 10–40 microglia/mouse, 4–5 mice/group; statistic: nested 2-tailed t test). (G) Sholl analysis and representative thresholded images of microglia from SWELL1 cKO and LM control mice (10–40 microglia/mouse, 4–5 mice/group; statistic: 2-way ANOVA). (H) Microglia (Iba1)–neuron (NeuN) interaction in CA3 pyramidal layer at 2 hours after kainate-induced seizure (6 animals/group examined). Scale bar: 50 μm. (I) Iba1-NeuN double-positive volume as a percentage of CA3 pyramidal layer volume (statistic: unpaired 2-tailed t test). (J) Microglia soma changes at 2 hours after seizure induction (90–160 microglia/mouse, 5–6 mice/group examined). Scale bar: 20 μm. (K) Quantification of microglia soma circularity in CA3 (dot, individual microglia; 90–160 microglia/mouse, 5–6 mice/group; statistic: nested 2-tailed t test). (L) Quantification of microglia soma size in CA3 (dot, individual microglia; 90–160 microglia/mouse, 5–6 mice/group; statistic: nested 2-tailed t test). LM, vehicle-treated littermate control; PL, pyramidal layer; Tam, tamoxifen. *P <0.05, ****P <0.001.