Abstract
Introduction
Neutrophils, crucial regulators of antimicrobial defense, also play a role in atherosclerosis. Signal transducer and activator of transcription 4 (STAT4)controls key neutrophil functions, including ROS generation, NETosis, and migration. Myeloid STAT4 deficiency reduces atherogenesis but impairs antimicrobial defense. Sleep fragmentation (SF), a widespread health concern, increases cardiovascular risk. SF accelerates atherosclerosis in a neutrophil-dependent manner by enhancing neutrophil functions.
Methods
Myeloid-specific STAT4-deficient low-density lipoprotein receptor-deficient (Stat4ΔLysMLdlr-/-) and control (Stat4fl/flLdlr-/-) mice were fed a high Fat, high cholesterol Diet (DDC) and randomly assigned to a SF or home cage control (HC) groups for 16 weeks. Survival was evaluated using kaplan-meier analysis. Atherosclerotic lesion formation was evaluated using Oil-red-O staining. Immune profiling was conducted on the aorta, blood, bone marrow, intestine, and peritoneal cavity using spectral flow Cytometry.
Results
Kaplan–Meier analysis revealed reduced survival in Stat4ΔLysMLdlr-/-mice compared to controls following SF but not in the HC controls. Oil red o staining of en face aortas showed reduced atherosclerosis Furthermore, Oil-Red-O staining of en face aortas and spectral flow cytometry analysis on circulating blood and peritoneal lavage fluid revealed that myeloid-specific STAT4 deficiency reduced neutrophil production, activation, and atherosclerosis, but also caused peritonitis and increased mortality after SF and DDC feeding in Stat4ΔLysMLdlr-/-mice vs Stat4fl/flLdlr-/-mice. Premature death was linked to peritonitis, possibly due to intestinal inflammation and barrier dysfunction, seen by increased ROS production in the small intestines and elevated plasma LPS levels.
Conclusion
Thus, we show that STAT4 critically balances immune responses during SF by driving inflammatory neutrophil activation that promotes atherosclerosis while simultaneously preserving essential host defense mechanisms, underscoring its dual role in modulating inflammation and survival under physiological stress.