PI3Kγ promotes neutrophil extracellular trap formation by noncanonical pyroptosis in abdominal aortic aneurysm
Yacheng Xiong, Shuai Liu, Yu Liu, Jiani Zhao, Jinjian Sun, Yongqing Li, Baihong Pan, Wei Wang
Yacheng Xiong, Shuai Liu, Yu Liu, Jiani Zhao, Jinjian Sun, Yongqing Li, Baihong Pan, Wei Wang
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Research Article Vascular biology

PI3Kγ promotes neutrophil extracellular trap formation by noncanonical pyroptosis in abdominal aortic aneurysm

Abstract

Abdominal aortic aneurysm (AAA) is one of the most life-threatening cardiovascular diseases; however, effective drug treatments are still lacking. The formation of neutrophil extracellular traps (NETs) has been shown to be a crucial trigger of AAA, and identifying upstream regulatory targets is thus key to discovering therapeutic agents for AAA. We revealed that phosphoinositide-3-kinase γ (PI3Kγ) acted as an upstream regulatory molecule and that PI3Kγ inhibition reduced NET formation and aortic wall inflammation, thereby markedly ameliorating AAA. However, the mechanism of NET formation regulated by PI3Kγ remains unclear. In this study, we showed that PI3Kγ deficiency inactivated the noncanonical pyroptosis pathway, which suppressed downstream NET formation. In addition, PI3Kγ regulation of noncanonical pyroptosis was dependent on cyclic AMP/protein kinase A signaling. These results clarify the molecular mechanism and crosstalk between PI3Kγ and NETosis in the development of AAA, potentially facilitating the discovery of therapeutic options for AAA.

Authors

Yacheng Xiong, Shuai Liu, Yu Liu, Jiani Zhao, Jinjian Sun, Yongqing Li, Baihong Pan, Wei Wang

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Figure 5

PI3Kγ expression in neutrophils is required for NETs’ formation and AAA progression in mice.

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PI3Kγ expression in neutrophils is required for NETs’ formation and AAA ...
(A) Schematic diagram of the experimental process of neutrophil adoptive transfer in PPE-induced AAA PI3Kγ–/– mice. (B) Representative ultrasound images and quantitative comparison of maximal lumen diameter in PI3Kγ–/– mice after PPE surgery. n = 8. Scale bar: 1 mm. (C) Representative macroscopic images and quantitative comparison of maximal aortic diameter in PI3Kγ–/– mice after PPE surgery. n = 8. (D) Representative VVG staining images and quantitative comparison of VVG staining score in PI3Kγ–/– mice after PPE surgery. n = 6. Scale bars, 50 μm. (E) Representative immunofluorescence staining images and quantitative comparison of NETs in PI3Kγ–/– mouse abdominal aorta after PPE-induced AAA. NETs’ expression was calculated by NET area/total area (%) according to the fluorescence colocalization of DNA (DAPI, blue), citrullinated histone 3 (Cit H3, green), and myeloperoxidase (MPO, red). n = 6. Scale bars, 50 μm. (F) Representative Western blot image and quantitative analysis of Cit H3 protein expression in the abdominal aorta of PI3Kγ–/– mice. n = 3. (G) qPCR analysis of contractile, synthetic, inflammation, and matrix metalloproteinase genes expression normalized to the mean expression of housekeeping gene (Actb) in abdominal aorta of PI3Kγ–/– mice from control and WT neutrophil adoptive transfer after PPE-induced AAA. n = 6. (B–F) Two-tailed unpaired Student’s t test. (G) Two-way ANOVA followed by Bonferroni’s test. *P < 0.05, **P < 0.01, and ***P < 0.001. iv, intravenous injection; VVG, Verhoeff Van Gieson.