Is there an immunogenomic difference between thoracic and abdominal aortic aneurysms?

Innovation in pathogenesis and management of aortic aneurysm

Aortic aneurysm (AA) refers to the persistent dilatation of the aorta, exceeding three centimeters. Investigating the pathophysiology of this condition is important for its prevention and management, given its responsibility for more than 25000 deaths in the United States. AAs are classified based on their location or morphology. various pathophysiologic pathways including inflammation, the immune system and atherosclerosis have been implicated in its development. Inflammatory markers such as transforming growth factor β, interleukin-1β, tumor necrosis factor-α, matrix metalloproteinase-2 and many more may contribute to this phenomenon. Several genetic disorders such as Marfan syndrome, Ehler-Danlos syndrome and Loeys-Dietz syndrome have also been associated with this disease. Recent years has seen the investigation of novel management of AA, exploring the implication of different immune suppressors, the role of radiation in shrinkage and prevention, as well as minimally invasive and newly hypothesized surgical methods. In this narrative review, we aim to present the new contributing factors involved in pathophysiology of AA. We also highlighted the novel management methods that have demonstrated promising benefits in clinical outcomes of the AA.

Single-cell RNA sequencing and ATAC sequencing identify novel biomarkers for bicuspid aortic valve-associated thoracic aortic aneurysm

Introduction

Bicuspid aortic valve (BAV) is the most prevalent congenital cardiovascular defect and known to cause thoracic aortic aneurysms (TAAs). To improve our understanding of BAV pathogenesis, we characterized the cellular composition of BAV tissues and identified molecular changes in each cell population.

Methods

Tissue samples from two patients with BAV and two heart transplant donors were analyzed using single-cell RNA sequencing, assay for transposase-accessible chromatin using sequencing, and weighted gene coexpression network analysis for differential gene analysis. TAA-related changes were evaluated by comparing the proportion of each cell type and gene expression profiles between TAA and control tissues. Further, by combining our single-cell RNA sequencing data with publicly available data from genome-wide association studies, we determined critical genes for BAV.

Results

We found 20 cell subpopulations in TAA tissues, including multiple subtypes of smooth muscle cells, fibroblasts, macrophages, and T lymphocytes. This result suggested that these cells play multiple functional roles in BAV development. Several differentially expressed genes, including CD9, FHL1y, HSP90AA1, GAS6, PALLD, and ACTA2, were identified.

Discussion

We believe that this comprehensive assessment of the cellular composition of TAA tissues and the insights into altered gene expression patterns can facilitate identification of novel diagnostic biomarkers and therapeutic targets for BAV-associated TAA.

Cellular, Molecular and Clinical Aspects of Aortic Aneurysm-Vascular Physiology and Pathophysiology

A disturbance of the structure of the aortic wall results in the formation of aortic aneurysm, which is characterized by a significant bulge on the vessel surface that may have consequences, such as distention and finally rupture. Abdominal aortic aneurysm (AAA) is a major pathological condition because it affects approximately 8% of elderly men and 1.5% of elderly women. The pathogenesis of AAA involves multiple interlocking mechanisms, including inflammation, immune cell activation, protein degradation and cellular malalignments. The expression of inflammatory factors, such as cytokines and chemokines, induce the infiltration of inflammatory cells into the wall of the aorta, including macrophages, natural killer cells (NK cells) and T and B lymphocytes. Protein degradation occurs with a high expression not only of matrix metalloproteinases (MMPs) but also of neutrophil gelatinase-associated lipocalin (NGAL), interferon gamma (IFN-γ) and chymases. The loss of extracellular matrix (ECM) due to cell apoptosis and phenotype switching reduces tissue density and may contribute to AAA. It is important to consider the key mechanisms of initiating and promoting AAA to achieve better preventative and therapeutic outcomes.

Study on the correlation between gene polymorphisms of adiponectin and resistin levels and abdominal aortic aneurysm

OBJECTIVES

Abdominal Aortic Aneurysm (AAA) is a complex disease with both genetic and environmental risk factors. This study aimed to examine the potential association of the +276G/T and -420C>G polymorphisms in the resistin gene with AAA susceptibility and progression.

METHOD

We performed a retrospective study involving AAA patients and healthy controls, assessing the distribution of the +276G/T and -420C>G genotypes in both groups. Hardy-Weinberg equilibrium was assessed for both polymorphisms. Logistic regression was used to explore the influence of these genotypes on AAA occurrence and progression, adjusting for relevant confounders.

RESULTS

The distribution of +276G/T polymorphism did not significantly differ between AAA patients and controls. Conversely, a significant difference was observed in the genotype distribution of -420C>G polymorphism between the two groups. The CC genotype and CC/CG genotypes of -420C>G polymorphism were found to be associated with an increased risk and progression of AAA.

CONCLUSIONS

The -420C>G polymorphism, particularly the CC genotype and CC/CG genotypes, might play a substantial role in AAA susceptibility and progression. The present findings underscore the need for further investigations to confirm these associations and fully elucidate the role of the resistin gene in AAA.