Therapeutic MK2 inhibition blocks pathological vascular smooth muscle cell phenotype switch

LncRNA MFRL regulates the phenotypic switch of vascular smooth muscle cells to attenuate arterial remodeling by encoding a novel micropeptide MFRLP

BACKGROUND

Arterial remodeling is a common pathophysiological change in the pathogenesis of cardiovascular diseases in which the phenotypic switch of vascular smooth muscle cells (VSMC) plays an important role. Recently, an increasing number of long non-coding RNAs(lncRNAs) have been shown to encode micropeptides that play biological roles and have great clinical transformation potential. However, the role of micropeptides encoded by lncRNAs in arterial remodeling has not been well studied and requires further exploration.

METHODS AND RESULTS

Through bioinformatic analysis and experimental verification, we found that a new lncRNA, the mitochondrial function-related lncRNA (MFRL), encodes a 64-amino acid micropeptide, MFRLP. MFRL and MFRLP play important roles in the phenotypic switch of VSMC. Further experiments showed that MFRLP interacts with mitochondrial cytochrome b to reduce accumulation of reactive oxygen species, suppress mitophagy and inhibit the VSMC switch from contractile to synthetic phenotype.

CONCLUSIONS

LncRNA MFRL encodes the micropeptide MFRLP, which interacts with mitochondrial cytochrome b to inhibit the VSMC switch from contractile to synthetic phenotype and improve arterial remodeling.

Analysis of Vascular Smooth Muscle Cells from Thoracic Aortic Aneurysms Reveals DNA Damage and Cell Cycle Arrest as Hallmarks in Bicuspid Aortic Valve Patients

Thoracic aortic aneurysm (TAA) is mainly sporadic and with higher incidence in the presence of a bicuspid aortic valve (BAV) for unknown reasons. The lack of drug therapy to delay TAA progression lies in the limited knowledge of pathophysiology. We aimed to identify the molecular hallmarks that differentiate the aortic dilatation associated with BAV and tricuspid aortic valve (TAV). Aortic vascular smooth muscle cells (VSMCs) isolated from sporadic TAA patients with BAV or TAV were analyzed by mass spectrometry. DNA oxidative damage assay and cell cycle profiling were performed in three independent cohorts supporting proteomics data. The alteration of secreted proteins was confirmed in plasma. Stress phenotype, oxidative stress, and enhanced DNA damage response (increased S-phase arrest and apoptosis) were found in BAV-TAA patients. The increased levels of plasma C1QTNF5, LAMA2, THSB3, and FAP confirm the enhanced stress in BAV-TAA. Plasma FAP and BGN point to an increased inflammatory condition in TAV. The arterial wall of BAV patients shows a limited capacity to counteract drivers of sporadic TAA. The molecular pathways identified support the need of differential molecular diagnosis and therapeutic approaches for BAV and TAV patients, showing specific markers in plasma which may serve to monitor therapy efficacy.

Aortic Cellular Heterogeneity in Health and Disease: Novel Insights Into Aortic Diseases From Single-Cell RNA Transcriptomic Data Sets

Aortic diseases such as atherosclerosis, aortic aneurysms, and aortic stiffening are significant complications that can have significant impact on end-stage cardiovascular disease. With limited pharmacological therapeutic strategies that target the structural changes in the aorta, surgical intervention remains the only option for some patients with these diseases. Although there have been significant contributions to our understanding of the cellular architecture of the diseased aorta, particularly in the context of atherosclerosis, furthering our insight into the cellular drivers of disease is required. The major cell types of the aorta are well defined; however, the advent of single-cell RNA sequencing provides unrivaled insights into the cellular heterogeneity of each aortic cell type and the inferred biological processes associated with each cell in health and disease. This review discusses previous concepts that have now been enhanced with recent advances made by single-cell RNA sequencing with a focus on aortic cellular heterogeneity.

Th2 cytokine signaling through IL-4Rα increases eotaxin-3 secretion and tension in human esophageal smooth muscle

In esophageal epithelial cells in eosinophilic esophagitis (EoE), Th2 cytokines (IL-4, IL-13) signal through IL-4Rα, activating JAK to increase eotaxin-3 secretion, which draws eosinophils into the mucosa. We explored whether Th2 cytokines also might stimulate eotaxin-3 secretion and increase tension in esophageal smooth muscle (ESM), which might impair esophageal distensibility, and whether those events could be blocked by proton pump inhibitors (PPIs) or agents that disrupt IL-4Rα signaling. We established human ESM cell cultures from organ donors, characterizing Th2 cytokine receptor and P-type ATPase expression by qPCR. We measured Th2 cytokine-stimulated eotaxin-3 secretion by enzyme-linked immunosorbent assay (ELISA) and ESM cell tension by gel contraction assay, before and after treatment with omeprazole, ruxolitinib (JAK inhibitor), or IL-4Rα blocking antibody. CPI-17 (inhibitor of a muscle-relaxing enzyme) effects were studied with CPI-17 knockdown by siRNA or CPI-17 phospho(T38A)-mutant overexpression. ESM cells expressed IL-4Rα and IL-13Rα1 but only minimal H+-K+-ATPase mRNA. Th2 cytokines increased ESM eotaxin-3 secretion and tension, effects blocked by ruxolitinib and IL-4Rα blocking antibody but not consistently blocked by omeprazole. IL-13 increased ESM tension by increasing CPI-17 expression and phosphorylation, effects blocked by CPI-17 knockdown. Blocking IL-4Rα decreased IL-13-stimulated eotaxin-3 secretion, CPI-17 expression, and tension in ESM. Th2 cytokines increase ESM eotaxin-3 secretion and tension via IL-4Rα signaling that activates CPI-17. Omeprazole does not reliably inhibit this process, but IL-4Rα blocking antibody does. This suggests that ESM eosinophilia and impaired esophageal distensibility might persist despite elimination of mucosal eosinophils by PPIs, and IL-4Rα blocking agents might be especially useful in this circumstance.NEW & NOTEWORTHY We have found that Th2 cytokines increase eotaxin-3 secretion and tension in esophageal smooth muscle (ESM) cells via IL-4Rα signaling. Unlike esophageal epithelial cells, ESM cells do not express H+-K+-ATPase, and omeprazole does not inhibit their cytokine-stimulated eotaxin-3 secretion or tension. An IL-4Rα blocking antibody reduces both eotaxin-3 secretion and tension induced by Th2 cytokines in ESM cells, suggesting that an agent such as dupilumab might be preferred for patients with EoE with esophageal muscle involvement.

[Transcriptome sequencing for identification of the genes associated with restenosis of venous grafts in rabbits]

OBJECTIVE

To identify the genes associated with venous graft restenosis in rabbits using transcriptome sequencing.

METHODS

Forty New Zealand rabbits were randomly divided into experimental group and control group, and in the experimental group, the left external jugular veins of the rabbits were engrafted to the left common carotid artery with continuous running suture; the rabbits in the control group received no operation. At 2 and 4 weeks after the operation, 10 rabbits from each group were euthanized and the venous grafts (in experimental group) or left external jugular vein (in control group) were harvested for measurement of the intima-media thickness using HE staining. RNA high-throughput sequencing (RNA-seq) was performed to identify the differentially expressed genes (DEGs) between the venous grafts and the control veins, and the biological functions of the DEGs were analyzed using GO and KEEG databases.

RESULTS

In the experimental group, intima-media thickening with increased extracellular matrix and vascular smooth muscle cell proliferation occurred in the venous grafts at 2 weeks and aggravated at 4 weeks after the operation. RNA high-throughput sequencing identified 1583 up-regulated genes and 608 down-regulated genes in the venous grafts in the experimental group, and GO and KEGG analysis of the DEGs pinpointed 10 hub genes, namely CD4, ZAP70, SYK, CD28, PIK3CD, CXCR4, CCR5, ITK, CCL5 and BTK.

CONCLUSION

CD4, ZAP70, SYK, CD28, PIK3CD, CXCR4, CCR5, ITK, CCL5 and BTK are probably the key genes associated with vein graft restenosis in rabbits.

MKL1 fuels ROS-induced proliferation of vascular smooth muscle cells by modulating FOXM1 transcription

Reactive oxygen species (ROS) promotes vascular injury and neointima formation in part by stimulating proliferation of vascular smooth muscle cells (VSMC). The underlying transcriptional mechanism, however, is not completely understood. Here we report that VSMC-specific deletion of MKL1 in mice suppressed neointima formation in a classic model of vascular injury. Likewise, pharmaceutical inhibition of MKL1 activity by CCG-1423 similarly mollified neointima formation in mice. Over-expression of a constitutively active MKL1 in vascular smooth muscle cells enhanced proliferation in a ROS-dependent manner. On the contrary, MKL1 depletion or inhibition attenuated VSMC proliferation. PCR array based screening identified forkhead box protein M1 (FOXM1) as a direct target for MKL1. MKL1 interacted with E2F1 to activate FOXM1 expression. Concordantly, FOXM1 depletion ameliorated MKL1-dependent VSMC proliferation. Of interest, ROS-induced MKL1 phosphorylation through MK2 was essential for its interaction with E2F1 and consequently FOXM1 trans-activation. Importantly, a positive correlation between FOXM1 expression and VSMC proliferation was identified in arterial specimens from patients with restenosis. Taken together, our data suggest that a redox-sensitive phosphorylation-switch of MKL1 activates FOXM1 transcription and mediates ROS fueled vascular smooth muscle proliferation. Targeting the MK-2/MKL1/FOXM1 axis may be considered as a reasonable approach for treatment of restenosis.

Vascular Smooth Muscle Cells Phenotypic Switching in Cardiovascular Diseases

Vascular smooth muscle cells (VSMCs), the major cell type in the arterial vessel wall, have a contractile phenotype that maintains the normal vessel structure and function under physiological conditions. In response to stress or vascular injury, contractile VSMCs can switch to a less differentiated state (synthetic phenotype) to acquire the proliferative, migratory, and synthetic capabilities for tissue reparation. Imbalances in VSMCs phenotypic switching can result in a variety of cardiovascular diseases, including atherosclerosis, in-stent restenosis, aortic aneurysms, and vascular calcification. It is very important to identify the molecular mechanisms regulating VSMCs phenotypic switching to prevent and treat cardiovascular diseases with high morbidity and mortality. However, the key molecular mechanisms and signaling pathways participating in VSMCs phenotypic switching have still not been fully elucidated despite long-term efforts by cardiovascular researchers. In this review, we provide an updated summary of the recent studies and systematic knowledge of VSMCs phenotypic switching in atherosclerosis, in-stent restenosis, aortic aneurysms, and vascular calcification, which may help guide future research and provide novel insights into the prevention and treatment of related diseases.

How vascular smooth muscle cell phenotype switching contributes to vascular disease

Vascular smooth muscle cells (VSMCs) are the most abundant cell in vessels. Earlier experiments have found that VSMCs possess high plasticity. Vascular injury stimulates VSMCs to switch into a dedifferentiated type, also known as synthetic VSMCs, with a high migration and proliferation capacity for repairing vascular injury. In recent years, largely owing to rapid technological advances in single-cell sequencing and cell-lineage tracing techniques, multiple VSMCs phenotypes have been uncovered in vascular aging, atherosclerosis (AS), aortic aneurysm (AA), etc. These VSMCs all down-regulate contractile proteins such as α-SMA and calponin1, and obtain specific markers and similar cellular functions of osteoblast, fibroblast, macrophage, and mesenchymal cells. This highly plastic phenotype transformation is regulated by a complex network consisting of circulating plasma substances, transcription factors, growth factors, inflammatory factors, non-coding RNAs, integrin family, and Notch pathway. This review focuses on phenotypic characteristics, molecular profile and the functional role of VSMCs phenotype landscape; the molecular mechanism regulating VSMCs phenotype switching; and the contribution of VSMCs phenotype switching to vascular aging, AS, and AA. Video Abstract.