Project description:Acute aortic dissection (AAD) is one of the major aortic diseases that occurs without a preceding symptom and often results in sudden death. Despite the recent advances in cardiovascular medicine, AAD remains a serious problem because its molecular pathogenesis is largely unknown. In this paper, we report our serendipitous discovery that stress-induced expression of tenascin C (TNC), a member of matricellular proteins, is the protection mechanism of aorta to prevent AAD. The aortic wall stress imposed by the aortic stiffening and the angiotensin II infusion caused the strong induction of TNC in wild type mouse aorta without gross morphological changes. While TNC knockout mice at the baseline showed no morphological, histological or biomechanical abnormalities of aorta, deletion of TNC gene rendered the aorta susceptible to AAD upon the aortic stress. The stressed TNC-null aorta showed the loss of the tensile strength due to the insufficient expression of extracellular matrix proteins and the exaggerated proinflammatory response before the onset of AAD. Therefore, TNC works as a stress-activated molecular damper both by reinforcing the tensile strength and by limiting the excessive proinflammatory response in aorta. Thus far, the molecular event that leads to the AAD development has been unclear because of the unpredictable nature of the AAD onset. This study sheds light on the previously unrecognized tissue protection mechanism that converts the potentially harmful stress response into the active reinforcement of the aorta, of which failure leads to the development of AAD. Although TNC is expressed in various tissues upon the mechanical and proinflammatory stimuli, its role has long been a mystery. Our data uncovered the adaptive role of TNC in aorta that must be resilient to the continuous hemodynamic and humoral stress for lifetime. We used periaortic application of 0.5 M CaCl2 to the infrarenal aorta or either wild type (WT) or tenascin C knockout (TNC-KO) mice to create the mouse model for stiffened aorta and infused the mice with AngII (1 µg/min/kg) for 1 week to apply the pathological stress on aorta (Ca+AngII). Mice were then killed with an overdose of pentobarbital to obtain the tissue samples. The suprarenal aortic samples, from the level of right renal artery to 10 mm above the right renal artery, and infrarenal aortic samples, from the level of left renal artery to 10 mm below the left renal artery, were collected and kept in RNAlater (Qiagen) until the extraction of total RNA using RNeasy (Qiagen). We obtained the RNA samples from 8 mice with Ca+AngII treatment and 5 mice without Ca+AngII treatment for each genotype. We pooled the RNA samples with the identical experimental condition to perform the transcriptome analysis using Mouse Genome 430 2.0 (Affymetrix). We obtained suprarenal aortic smooth muscle cells (ASMCs) from TNC-KO mice by enzymatic dispersion and cultured them in Dulbecco's modified Eagle medium (DMEM) supplemented with 10% fetal bovine serum. We cultured TNC-KO ASMCs in the presence or absence of exogenous TNC (10 µg/mL) and stimulated the cells with 10 ng/mL TNF-alpha for 24 h before obtaining total RNA using RNeasy. We used 3 independent ASMC cultures without the exogenous TNC and 4 independent cultures with the exogenous TNC. We hybridized each of the RNA samples individually to Mouse Genome 430 2.0 Array (Affymetrix).

Project description:Stanford type A aortic dissection (STAAD) is an aortic degenerative remodeling disease carrying an exceedingly high mortality worldwide. The irreversible weakening, dilatation and dissection of the ascending aorta contributes to circulatory failure and premature death. Dissections manifest distinct patterns in both clinical presentations and histophathological features during disease temporal transition. Therefore, we delineate a full repertoire of cellular landscape and dynamic interplay in distinct temporal patterns of STAAD using single-cell transcriptomics for comprehensively understanding of disease features and temporal evolution. We performed single-cell RNA sequencing with ascending aortic tissues from 14 participants, including 9 patients with STAAD (4 acute, 3 subacute, and 2 chronic) and 5 control subjects. Unsupervised clustering was performed based on transcriptional profiles of highly variable genes. Single T cell analysis by RNA sequencing and TCR tracking (STARTRACT) was performed to quantitatively delineate the developmental trajectory of aortic T lymphocytes. On the basis of molecular signatures and distinct disease patterns, we draw a spatiotemporal map of disease subtype-specific alterations and complex interplay among cell types. The transcriptional profiles of 93,397 individual cells enable us to identify 12 major cell types and 37 subtypes in human ascending aorta. Comparisons of transcriptomes of disease subtypes reveal striking stage-specific cellular diversity and transcriptional dynamics in phenotypic switch, vascular inflammation, cell death and survival, extracellular matrix remodeling, and cell-cell interactions during disease temporal transition. Modeling of developmental trajectory revealed that the defects in mitochondrial OXPHOS drives phenotypic switch of contractile smooth muscle cells to synthetic myofibroblasts through AP-1 transcriptional complex. STARTRACT analysis revealed that CD8+ HSP are preferentially enriched and potentially clonally expanded in acute AD. Intersection of disease risk genes with our dataset reveals distinct gene panel in discriminating temporal-specifc AD. This compendium of transcriptome data provides valuable insights and a rich resource for understanding the cellular diversity and heterogeneity in human aorta. The distinct alterations of cell type- and disease subtype-specific spatiotemporal features will ultimately facilitate the design of more precisely tailored anti-AD therapies.

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Single Cell RNA Sequence Reveals a Distinct Immune Landscape in Acute Aortic Dissection.

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