Circulation research最新文献

Background: Short-term blood pressure (BP) variability is increasingly recognized as an independent predictor of cardiovascular and cerebrovascular risks, yet the central neural mechanisms that govern this variability, particularly across behavioral states, remain poorly defined.

Methods: We investigated the role of rostral ventrolateral medulla C1 (RVLM^C1) neurons in short-term BP regulation during sleep-wake transitions and physical activity in freely behaving rats. Genetically targeted fiber photometry was used to record RVLM^C1 neuronal activity across behavioral states. The contribution of feedback from the arterial baroreflex to the activity of RVLM^C1 neurons was assessed using sinoaortic denervation. Selective genetic ablation of RVLM^C1 neurons was performed to determine their role in BP regulation.

Results: RVLM^C1 neurons exhibited state-dependent activity, with rapid activation during arousal from nonrapid eye movement sleep, sustained activity during rapid eye movement sleep, and further recruitment during physical activity. Baroreflex input contributed to the modulation of RVLM^C1 neuron activity by pharmacological manipulations of BP and transitions from nonrapid eye movement sleep to rapid eye movement sleep. Selective ablation of RVLM^C1 neurons did not alter mean BP but resulted in marked BP instability during arousal and movement.

Conclusions: RVLM^C1 neurons stabilize BP during changes in the behavioral state by integrating arousal-related central drive with baroreceptor feedback. Disruption of these neurons leads to increased short-term BP variability despite preserved mean BP, providing a potential neural mechanism underlying pathological BP instability.

Background: Atherosclerosis commences with endothelial dysfunction and the retention of cholesterol within the vessel wall, followed by a chronic inflammatory response. Lowering LDL-C (low-density lipoprotein-cholesterol; such as statins and PCSK9 [proprotein convertase subtilisin/kexin type 9] inhibitors) is the mainstay of current treatment for patients with atherosclerotic cardiovascular diseases, but residual inflammatory risk remains high.

Methods: To address this pressing challenge, we used connectivity map screening of Food and Drug Administration-approved drugs, using perturbational data sets obtained from TNF-α (tumor necrosis factor-α) and IL (interleukin)-1β-stimulated human endothelial cells. Male and female Ldlr^-/- mouse models were used to evaluate the in vivo antiatherosclerotic effect of the hit compound identified.

Results: This screening endeavor allows us to identify neratinib, a clinical drug against breast cancer, as the hit compound with broad anti-inflammatory actions in endothelial cells. Further studies reveal that neratinib inhibited endothelial cell inflammation elicited by 3 different proinflammatory stimuli (TNF-α, IL-1β, and lipopolysaccharide). Intriguingly, the anti-inflammatory effect of neratinib was independent of its classical target HER2 (human epidermal growth factor receptor 2). Further mechanistic investigation revealed that neratinib directly binds to ASK1 (apoptosis signal-regulating kinase 1) and suppresses ASK1 activation. Importantly, in both male and female Ldlr^-/- mice, treatment with neratinib decreased the plaque burden, reduced the necrotic core size, and mitigated lesional macrophage infiltration. Of translational impact, we observed that neratinib, in conjunction with the use of rosuvastatin (a standard lipid-lowering drug), produced superior antiatherosclerotic effects compared with statin monotherapy. Olink proteomics study pinpointed that combination treatment alleviated inflammation-related cytokines/chemokines in the serum from Ldlr^-/- mice.

Conclusions: Taken together, these findings support the concept that neratinib could be tested as a repurposed drug for vascular inflammation and atherosclerosis, thereby streamlining efforts to translate preclinical discoveries to clinical testing in humans.

Background: Pulmonary interstitial macrophages can be divided into 2 distinct subsets with different origins: resident macrophages (resMФs) and recruited macrophages (recMФs). However, their specific roles in pulmonary arterial hypertension remain unclear.

Methods: Bone marrow transplantation, the DT (diphtheria toxin) receptor system, and genetically modified murine models were utilized to explore how key TFs (transcription factors) regulate phenotype alterations in pulmonary resMФs and recMФs in an SU5416/hypoxia murine model of pulmonary hypertension (PH). Therapeutic approaches included DNA aptamer-based proteolysis-targeting chimera and small interfering RNA-loaded lipid nanoparticle for treating SU5416/hypoxia-exposed rats.

Results: Depletion of either resMФs or recMФs using DT treatment significantly reduced SU5416/hypoxia-induced PH in mice. Pulmonary recMФs exhibited a proinflammatory phenotype during PH, driven by the TF Hic1 (hypermethylated in cancer 1). Bone marrow transplantation with Hic1^-/- recMФs ameliorated PH in mice. Hic1 enhanced proinflammatory gene transcription by inhibiting Sirt1 (sirtuin 1)-mediated H3K9ac (histone H3 lysine 9 acetylation) deacetylation in the promoter regions. In contrast, pulmonary resMФs demonstrated a profibrotic transcriptome characterized by upregulation of MMP genes that are, in turn, regulated by Prrx2 (paired-related homeobox 2). Prrx2 deletion in resMФs protected against PH in mice by reducing perivascular fibrosis. Simultaneously targeting Prrx2 and Hic1 in macrophages significantly alleviated SU5416/hypoxia-induced PH in rats.

Conclusions: The differential roles of pulmonary resMФs and recMФs in pulmonary vascular remodeling highlight novel therapeutic targets for pulmonary arterial hypertension treatment, specifically through inhibition of Hic1 and Prrx2 in macrophages.

Background: Abdominal aortic aneurysms (AAAs) are characterized by ECM (extracellular matrix) degradation and chronic vascular inflammation, with macrophages playing a key role. The mechanisms regulating macrophage activation in AAA remain incompletely understood. Vascular macrophages express Olfr2 (olfactory receptor 2), a GPCR (G-protein-coupled receptor) implicated in inflammation, but its role in AAA development is unknown.

Methods: We investigated the role of Olfr2 in AAA using PPE (porcine pancreatic elastase) infusion in Olfr2-deficient (Olfr2^-/-), Ang II (angiotensin II) infusion in Apoe^-/- Olfr2^-/-mice, bone marrow transplantation, and pharmacological modulation experiments. Echocardiography and histology were complemented by spectral flow cytometry, transcriptional profiling, and functional in vivo and ex vivo assays.

Results: Microarray analysis revealed increased expression of the human Olfr2 orthologue OR6A2 (olfactory receptor family 6 subfamily A member 2) in AAA tissue. Flow cytometry showed OR6A2 upregulation in monocytes from patients with large versus small AAAs. In both human and murine tissues, up to 30% of vascular macrophages expressed OR6A2/Olfr2, which peaked in MHCII^high CCR2^low monocytes/macrophages on day 7 of experimental AAA. Both whole-body and hematopoietic Olfr2 deficiency protected mice from AAA formation, with reduced ECM degradation, decreased macrophage infiltration, and preserved smooth muscle cell content. Treatment with the Olfr2 agonist octanal exacerbated, while the antagonist citral reduced AAA and inflammation. In Olfr2^-/- mice, inflammatory gene expression and aortic leukocyte accumulation were diminished. Despite a similar total leukocyte count, Ly6C^high monocytes displayed reduced CX3CR1 (CX3C motif chemokine receptor 1) expression and impaired migration toward CX3CL1 in vitro. Competitive transfer confirmed reduced migratory capacity of Olfr2^-/- monocytes, while pharmacological CX3CR1 inhibition mitigated the proinflammatory effects of octanal in AAA.

Conclusions: Olfr2 regulates monocyte recruitment and macrophage-driven inflammation during AAA. Its genetic deletion or pharmacological inhibition protects against AAA, whereas receptor activation worsens the disease. Olfr2 represents a critical modulator of vascular inflammation and a potential therapeutic target in AAA.

Background: Truncating variants in the TTN gene (TTNtv), encoding the giant sarcomeric protein titin, cause a range of human cardiac and skeletal muscle disorders of varying penetrance and severity. The effects of variant location on clinical manifestations are incompletely understood.

Methods: We generated 6 zebrafish lines carrying truncating ttn.2 variants in the Z-disk, I-band, A-band, and M-band titin regions. Expression of titin transcripts and protein levels was evaluated using quantitative polymerase chain reaction and proteomics. Phenotype analysis was performed during embryonic development and in adult hearts.

Results: Homozygous embryos from all lines except the C-terminal line, e232, showed a significant reduction of Z-disk and I-band ttn.2 transcripts, but A-band and M-band transcript levels were reduced only in lines with truncations distal to the cronos promoter. These homozygous embryos uniformly died by 7 to 10 days postfertilization with marked impairment of cardiac morphology and function. Skeletal muscle motility and sarcomere organization were more disrupted in mutants with truncations distal to the cronos promoter compared with those proximal. In contrast, homozygous e232 embryos, which lacked only the titin kinase and M-band regions, had relatively preserved cardiac function with incorporation of truncated Ttn.2/Cronos protein and normal sarcomere assembly, but selective degradation of fast skeletal muscle sarcomeres. All heterozygous embryos were phenotypically indistinguishable from wild type. High-frequency echocardiography in adult heterozygous fish showed reduced ventricular contraction under resting conditions in A-band mutants. Heterozygous Z-disk and I-band mutants had no significant baseline impairment but were unable to augment ventricular contraction in response to acute adrenaline exposure, indicating a lack of cardiac reserve.

Conclusions: Our data suggest that cardiac and skeletal muscle dysfunction associated with truncating ttn.2 variants is influenced by age, variant location, and the amount of functional titin protein. The distinctive phenotype associated with distal C-terminal truncations may reflect different requirements for C-terminal titin for maintenance of fast, slow, and cardiac muscle sarcomeres.