BACKGROUND: Abdominal aortic aneurysm (AAA) is a catastrophic disease with little effective therapy, likely due to the limited understanding of the mechanisms underlying AAA development and progression. ATF3 (activating transcription factor 3) has been increasingly recognized as a key regulator of cardiovascular diseases. However, the role of ATF3 in AAA development and progression remains elusive. METHODS: Genome-wide RNA sequencing analysis was performed on the aorta isolated from saline or Ang II (angiotensin II)–induced AAA mice, and ATF3 was identified as the potential key gene for AAA development. To examine the role of ATF3 in AAA development, vascular smooth muscle cell–specific ATF3 knockdown or overexpressed mice by recombinant adeno-associated virus serotype 9 vectors carrying ATF3, or shRNA-ATF3 with SM22α (smooth muscle protein 22-α) promoter were used in Ang II–induced AAA mice. In human and murine vascular smooth muscle cells, gain or loss of function experiments were performed to investigate the role of ATF3 in vascular smooth muscle cell proliferation and apoptosis. RESULTS: In both Ang II–induced AAA mice and patients with AAA, the expression of ATF3 was reduced in aneurysm tissues but increased in aortic lesion tissues. The deficiency of ATF3 in vascular smooth muscle cell promoted AAA formation in Ang II–induced AAA mice. PDGFRB (platelet-derived growth factor receptor β) was identified as the target of ATF3, which mediated vascular smooth muscle cell proliferation in response to TNF-alpha (tumor necrosis factor-α) at the early stage of AAA. ATF3 suppressed the mitochondria-dependent apoptosis at the advanced stage by upregulating its direct target BCL2. Our chromatin immunoprecipitation results also demonstrated that the recruitment of NFκB1 and P300/BAF/H3K27ac complex to the ATF3 promoter induces ATF3 transcription via enhancer activation. NFKB1 inhibitor (andrographolide) inhibits the expression of ATF3 by blocking the recruiters NFKB1 and ATF3-enhancer to the ATF3-promoter region, ultimately leading to AAA development. CONCLUSIONS: Our results demonstrate a previously unrecognized role of ATF3 in AAA development and progression, and ATF3 may serve as a novel therapeutic and prognostic marker for AAA.

Atherosclerosis is a chronic inflammatory disease and a major pathological basis of numerous cardiovascular conditions, with a high global mortality rate. Macrophages play a pivotal role in its pathogenesis through phenotypic switching and foam cell formation. Prostaglandin E2 receptor subtype 4 (EP4) highly expressed on the macrophage surface, is involved in various pathophysiological processes, such as inflammation and lipid metabolism. However, the role of macrophage EP4 in the progression of atherosclerosis remains unclear. To determine whether macrophage EP4 affects the progression of atherosclerosis by regulating foam cell formation and macrophage polarization. Myeloid-specific EP4 knockout mice with an ApoE-deficient background were fed a Western diet for 16 weeks. Our results showed that EP4 expression was significantly downregulated during atherosclerosis. EP4 deficiency was found to exacerbate atherosclerotic plaque formation and destabilizes plaques. In vitro studies further demonstrated that loss of EP4 in myeloid cells promoted foam cell formation and M1 macrophage polarization. Both transcriptomic and proteomic analysis showed that EP4 may regulate these processes by regulating CD36 expression in macrophage, which was further confirmed by Western blot and qPCR. In summary, deficiency of EP4 receptor in macrophages enhance foam cell formation and M1 polarization by upregulating CD36 expression, thereby accelerating the progression of atherosclerosis.

Biliary atresia (BA) is a progressive neonatal cholangiopathy characterized by unresolved inflammation and neutrophil extracellular traps (NET) formation. Although neutrophils contribute to bile duct injury, the upstream mechanisms driving their activation remain poorly defined. This study investigated whether platelet (PLT) hyperactivation promotes NET-mediated inflammation in BA and evaluated the therapeutic potential of targeting S100A8/A9. The role of PLT hyperactivation in neutrophil-mediated inflammation in BA was evaluated through retrospective clinical review, single-cell RNA sequencing, and cell coculture experiments. The therapeutic potential of paquinimod, a small-molecule inhibitor that blocks S100A8/A9 binding to Toll-like receptor 4 on PLT and thereby suppresses PLT activation, was evaluated in a murine model of BA. Elevated PLT counts were observed in 54.2% (236/435) of patients with BA, and PLT hyperactivation (CD62p⁺) was increased in both patients and RRV-injected mice (p <0.0001). Single-cell analysis identified an expanded hyperactivated PLT subset enriched in proinflammatory pathways. Mechanistically, PLTs from patients with BA exhibited mitochondrial dysfunction and released oxidized mitochondrial DNA (ox-mtDNA), thereby promoting NET formation. An expanded population of S100⁺ neutrophils (47.0% vs. 14.3%, p <0.0001) expressing S100A8/A9 established a self-perpetuating inflammatory circuit that amplified PLTs activation and enhanced proinflammatory cytokine production (IL-1β, IL-6, tumor necrosis factor-alpha, p <0.001). In the murine model, treatment with paquinimod suppressed platelet activation, reduced hepatic NET formation, and significantly improved survival (83.3% vs. 0.0%, p <0.0001). PLT hyperactivation drives ox-mtDNA-dependent NET formation and amplifies inflammatory signaling in BA. Pharmacological inhibition of S100A8/A9 with paquinimod attenuates disease progression in mice. Biliary atresia is a serious neonatal liver disease featuring bile duct inflammation and obstruction. Here, hyperactivated PLTs in biliary atresia patients released ox-mtDNA, triggering NET formation and exacerbating liver injury. Blocking the key inflammatory mediator S100A8/A9 with paquinimod reduced PLT activation and liver inflammation and improved survival in mice. These findings reveal a vicious immune cycle between PLTs and neutrophils and highlight novel treatment options for attenuating disease progression.

Abdominal aortic aneurysm (AAA) is a serious disease with no effective pharmacological therapy. Although inflammation is recognized as a key regulator of AAA, targeting inflammatory pathways once the disease is established does not improve outcomes. Understanding the earliest molecular indicators could clarify precise biological targets and prognostic markers for AAA. Using ApoE-deficient mice, we performed RNA-Seq on suprarenal abdominal aortas (SRAs) from Ang II- and saline-treated mice 24 h after infusion. We further developed a unique model of hyperlipidemic mice in which the expression of the inhibitor of nuclear factor kappa B kinase subunit beta (IKKβ) can be conditionally suppressed in vascular smooth muscle cells (VSMCs). RNA-Seq data revealed early IKKβ-dependent cellular anabolic processes in SRAs, including activation of the mammalian target of rapamycin complex 1 (mTORC1) pathway. Furthermore, deletion of the Ikbkb gene in VSMCs significantly reduced the rate of aneurysm rupture in mice exposed to Ang II. In situ analysis further confirmed that the absence of IKKβ in VSMCs is associated with a reduced inflammatory response and the preservation of their contractile phenotypes. Our results reinforce the crucial role of VSMCs in rapid adaptation, leading to deleterious inflammation-dependent remodeling of the vascular wall, and define a previously unrecognized anabolic role of IKKβ in AAA pathogenesis.