The Ca2+-gated channel TMEM16A amplifies capillary pericyte contraction and reduces cerebral blood flow after ischemia
Nils Korte, … , David Attwell, Paolo Tammaro
Nils Korte, … , David Attwell, Paolo Tammaro
Published March 22, 2022
Citation Information: J Clin Invest. 2022;132(9):e154118. https://doi.org/10.1172/JCI154118.
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Research Article Cell biology Vascular biology

The Ca2+-gated channel TMEM16A amplifies capillary pericyte contraction and reduces cerebral blood flow after ischemia

Abstract

Pericyte-mediated capillary constriction decreases cerebral blood flow in stroke after an occluded artery is unblocked. The determinants of pericyte tone are poorly understood. We show that a small rise in cytoplasmic Ca2+ concentration ([Ca2+]i) in pericytes activated chloride efflux through the Ca2+-gated anion channel TMEM16A, thus depolarizing the cell and opening voltage-gated calcium channels. This mechanism strongly amplified the pericyte [Ca2+]i rise and capillary constriction evoked by contractile agonists and ischemia. In a rodent stroke model, TMEM16A inhibition slowed the ischemia-evoked pericyte [Ca2+]i rise, capillary constriction, and pericyte death; reduced neutrophil stalling; and improved cerebrovascular reperfusion. Genetic analysis implicated altered TMEM16A expression in poor patient recovery from ischemic stroke. Thus, pericyte TMEM16A is a crucial regulator of cerebral capillary function and a potential therapeutic target for stroke and possibly other disorders of impaired microvascular flow, such as Alzheimer’s disease and vascular dementia.

Authors

Nils Korte, Zeki Ilkan, Claire L. Pearson, Thomas Pfeiffer, Prabhav Singhal, Jason R. Rock, Huma Sethi, Dipender Gill, David Attwell, Paolo Tammaro

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Figure 8

Blocking TMEM16A partially restores capillary perfusion after CCAO.

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Blocking TMEM16A partially restores capillary perfusion after CCAO. (A) ...
(A) Isolectin B4–labeled cortical capillaries in fixed slices (purple); FITC-albumin in gelatin (recolored red) shows perfused vessels 1.5 hours after sham operation or CCAO without or with Ani9 (10 μM). Yellow arrows indicate pericyte somata less than 5 μm from capillary blocks. Right images show 3D tracing of FITC-albumin in perfused (white) or unperfused (magenta) capillaries. Scale bar: 20 μm. (B) Cumulative probability distribution of distance of 110 pericyte somata to capillary occlusions (black). The red line denotes the predicted distribution assuming pericytes are uniformly spaced along the capillary (see Supplemental Figure 5E) and blocks occur randomly (2-sample Kolmogorov-Smirnov test). (C) Extent of perfusion of 3D-traced capillaries. Points indicate individual confocal stacks from P30–P72 CCAO (aCSF) (n = 25), P31–P83 CCAO Ani9 (n = 16), and P39–P62 sham aCSF (n = 9) mice (Kruskal-Wallis test with Dunn’s post hoc test). (D) Ly6G-labeled neutrophil in a third order capillary in a fixed cortical slice at 1.5 hours after CCAO. The neutrophil obstructs blood flow (revealed by FITC-gelatin staining). Zoomed-in image of the right end of the block and left end of neutrophil (“Block start”) shows a possible red blood cell (RBC) to the left of the neutrophil. Scale bar: 10 μm. (E) Distribution of 109 neutrophils versus distance from the nearest pericyte soma. (F) Neutrophils in cerebral capillaries per confocal stack at 1.5 hours after CCAO in the absence (n = 18) or presence (n = 33) of Ani9 (10 μM) (Mann-Whitney test). (G) CD41-labeled platelets (or aggregates thereof) in third and fourth order capillary branches in a fixed cortical slice at 1.5 hours after CCAO. (H) Platelets (or platelet aggregates) in cerebral capillaries per confocal stack at 1.5 hours after CCAO in the absence (n = 71) or presence (n = 60) of Ani9 (10 μM) (Mann-Whitney test). The numbers of animals are specified in Supplemental Table 2.