Impaired Fas-induced apoptosis of T lymphocytes in patients with abdominal aortic aneurysms

Admission D-dimer to lymphocyte counts ratio as a novel biomarker for predicting the in-hospital mortality in patients with acute aortic dissection

BACKGROUND

Inflammatory factors are well-established indicators for vascular disease, but the D-dimer to lymphocyte count ratio (DLR) is not measured in routine clinical care. Screening of DLR in individuals may identify individuals at in-hopital mortality of acute aortic dissection (AD).

METHODS

A retrospective analysis of clinical data from 2013 to 2020 was conducted to identify which factors were related to in-hospital mortality risk of AD. Baseline clinical features, cardiovascular risk factors, and laboratory parameters were obtained from the hospital database. The end point was in-hospital mortality. Forward conditional logistic regression was performed to identify independent risk factors for AA in-hospital death. The cutoff value of the DLR should be ideally calculated by receiver operating characteristic (ROC) analysis.

RESULTS

The in-hospital mortality rate was 15% (48 of 320 patients). Patients with in-hospital mortality had a higher admission mean DLR level than the alive group (1740 vs. 1010, P < .05). The cutoff point of DLR was 907. The in-hospital mortality rate in the high-level DLR group was significantly higher than that in the low-level DLR group (P < .05). Univariate analysis showed that 8 of 38 factors were associated with in-hospital mortality (P < .05), including admission WBC, neutrophils, lymphocytes, neutrophils/lymphocytes (NLR), prothrombin time (PT), heart rate (HR), D-dimer, and DLR. In multivariate analysis, DLR (odds ratio [OR] 2.127, 95% CI 1.034-4.373, P = 0.040), HR (odds ratio [OR] 1.016, 95% CI 1.002-1.030, P = 0.029) and PT (odds ratio [OR] 1.231, 95% CI 1.018-1.189, P = 0.032) were determined to be independent predictors of in-hospital mortality (P < .05).

CONCLUSION

Compared with the common clinical parameters PT and HR, serum DLR level on admission is an uncommon but independent parameter that can be used to assess in-hospital mortality in patients with acute AD.

Human abdominal aortic aneurysm (AAA): Evidence for an autoimmune antigen-driven disease

Abdominal aortic aneurism (AAA) is a complex immunological disease with a strong genetic component, and one of the ten leading causes of death of individuals 55-74 years old worldwide. Strong evidence has been accumulated suggesting that AAA is an autoimmune specific antigen-driven disease. Mononuclear cells infiltrating AAA lesions comprised of T and B lymphocytes and other cells expressing early-, intermediate- and late-activation antigens, and the presence of antigen-presenting cells have been documented, demonstrating an ongoing immune response. The three components of the trimolecular complex, T-cell receptor (TCR)/peptide (antigen)/HLA have been identified in AAA, and specifically: (i) clonal expansions of T-cell clones in AAA lesions; (ii) the association of AAA with particular HLA Class I and Class II; and (iii) self or nonself putative AAA-associated antigens. IgG autoantibodies recognizing proteins present in normal aortic tissue have been reported in patients with AAA. Molecular mimicry, defined as the sharing of antigenic epitopes between microorganisms (bacteria, viruses) and self antigens, maybe is responsible for T-cell responses and antibody production in AAA. Also, the frequency and the suppressor activity of CD4 + CD25 + FOXP3+ Tregs and the expression of FOXP3 transcripts and protein have been reported to be significantly impaired in AAA patients vs normal donors.

Programmed cell death in aortic aneurysm and dissection: A potential therapeutic target

Rupture of aortic aneurysm and dissection (AAD) remains a leading cause of death. Progressive smooth muscle cell (SMC) loss is a crucial feature of AAD that contributes to aortic dysfunction and degeneration, leading to aortic aneurysm, dissection, and, ultimately, rupture. Understanding the molecular mechanisms of SMC loss and identifying pathways that promote SMC death in AAD are critical for developing an effective pharmacologic therapy to prevent aortic destruction and disease progression. Cell death is controlled by programmed cell death pathways, including apoptosis, necroptosis, pyroptosis, and ferroptosis. Although these pathways share common stimuli and triggers, each type of programmed cell death has unique features and activation pathways. A growing body of evidence supports a critical role for programmed cell death in the pathogenesis of AAD, and inhibitors of various types of programmed cell death represent a promising therapeutic strategy. This review discusses the different types of programmed cell death pathways and their features, induction, contributions to AAD development, and therapeutic potential. We also highlight the clinical significance of programmed cell death for further studies.

Overview of IgG4-related aortitis and periaortitis. A decade since their first description

Aortic involvement is relatively common in the context of IgG4-related disease (IgG4-RD). It includes IgG4-aortitis, and IgG4-(chronic) periaortitis (IgG4-CP). The latter overlaps with IgG4-retroperitoneal fibrosis (IgG4-RPF). Aortic wall thickening which characterizes these entities along with the presence of periaortic tissue in IgG4-CP, are often accompanied by aortic aneurysms, which belong to the group of the so-called inflammatory aneurysms. Both the thoracic and abdominal aorta can be affected. Aortitis appears to involve more often the former, while the opposite is the case for IgG4-CP. There is a lack of definitions and different classification criteria have been used to describe these entities. This report provides an overview on the current evidence of aortic involvement in IgG4-RD. It discusses the clinical, epidemiologic, serologic and histopathologic characteristics, as well as the imaging techniques used for their diagnosis and the therapeutic options and treatment outcomes. The differential diagnosis and underlying pathogenetic mechanisms are also discussed.

AEBP1 Promotes the Occurrence and Development of Abdominal Aortic Aneurysm by Modulating Inflammation via the NF-κB Pathway

AIM

Inflammation plays a significant role in the pathogenesis of human abdominal aortic aneurysm (AAA). AEBP1 can promote activation of the NF-κB pathway, subsequently affecting the expression of NF-κB target genes, including inflammatory cytokines and matrix metalloproteinases (MMPs). Our objective was to examine the role of AEBP1 in the development of AAA and characterize the underlying mechanism.

METHODS

ITRAQ, RT-PCR, western blot, immunohistochemistry, and ELISA were used to compare different experimental groups with the controls and to determine the differentially expressed genes. We generated an AAA model using porcine pancreatic elastase in Sprague-Dawley rats and silenced their AEBP1 in vivo by adenoviruses injected intra-adventitially. We also silenced or overexpressed AEBP1 in human vascular smooth muscle cells in vitro in the presence and in the absence of NF-κB inhibitor BAY 11-7082.

RESULTS

Proteome iTRAQ revealed a high expression of AEBP1 in AAA patients, which was verified by qRT-PCR, western blot, immunohistochemistry, and ELISA. The mean expression level of AEBP1 in AAA patients was higher than that in controls. Along with AEBP1 upregulation, we also verified mis-activation of NF-κB in human AAA samples. The in vivo studies indicated that AEBP1 knockdown suppressed AAA progression. Finally, the in vitro studies illustrated that AEBP1 promotes activation of the NF-κB pathway, subsequently upregulating pro-inflammatory factors and MMPs.

CONCLUSIONS

Our results indicate a role of AEBP1 in the pathogenesis of AAA and provide a novel insight into how AEBP1 causes the development of AAA by activating the NF-κB pathway.

Ulinastatin Inhibits the Formation and Progression of Experimental Abdominal Aortic Aneurysms

AIMS

Aortic mural inflammatory damage takes a vital part in abdominal aortic aneurysm (AAA). Recently, ulinastatin (UTI) has attracted attention for its anti-inflammatory function. Our study aimed to evaluate potential influences of UTI on experimental AAA.

METHODS

A mouse model of AAA was induced by infusion of porcine pancreatic elastase (PPE) into the abdominal aorta. Mice were treated with UTI (50,000 U/kg/day i.p.) beginning either immediately or on the 4th day after PPE infusion, with treatment being continued until the 14th day. UTI effects were assessed by aortic diameter measurements and aortic histopathological analysis.

RESULTS

Significant and time-dependent aortic diameter enlargement persisted in the control mice from day 0. In the UTI group, aortic diameter increased, and depletion of aortic mural smooth muscle cells and elastin was significantly -attenuated. Simultaneously, mural CD68+ macrophages, CD8+ T-cell and B220+ B-cell density, as well as neoangiogenesis were suppressed by UTI. In addition, delayed UTI treatment could still effectively limit aneurysm expansion.

CONCLUSIONS

UTI treatment limits the formation and growth of experimental AAA, and UTI may be a potential treatment for early AAA disease.

Epigenetic regulation of regulatory T cells in patients with abdominal aortic aneurysm

Abdominal arterial aneurysm (AAA) shares many features with autoimmune diseases and appears to be a T-cell-mediated process. In addition, certain epigenetic changes, including DNA methylation, are associated with AAA. In this study, we investigated epigenetic modifications in regulatory T cells (Tregs) from AAA patients. We used flow cytometry to sort FOXP3⁺ CD4⁺ CD25⁺ Tregs from the peripheral blood of AAA patients and from healthy controls (HC), and then detected DNA methylation and histone modifications by ELISA. The DNA methylation rate of Tregs was significantly higher in AAA patients than in the HC group (0.159 ± 0.08% vs 0.098 ± 0.03%, P < 0.05), while the acetylation rates of H3 and H3K9 histones were lower in the AAA than in the HC group. We also examined the expression of mRNA encoding enzymes that catalyze making and removing epigenetic modifications by real-time PCR: we found that mRNA levels of DNA methyltransferase (DNMT) 1 and DNMT3A were higher in the AAA than in the HC group, mRNA levels of methyl-CpG-binding domain protein (MBD) 2 and MBD4 were higher in the AAA than in the HC group (MBD2: 6.21 ± 2.57 vs 3.04 ± 1.45; MBD4: 7.76 ± 3.48 vs 4.97 ± 3.10; both P < 0.05), and mRNA levels of histone deacetylase (HDAC) 1 and HDAC5 were significantly up-regulated in the AAA compared with the HC group (HDAC1: 2.17 ± 1.18 vs 1.51 ± 0.99; HDAC5: 1.35 ± 0.49 vs 0.94 ± 0.76; both P < 0.05). Together, our results reveal that rates of DNA methylation and histone modifications of Tregs are significantly altered in AAA patients.

Systemic inflammatory markers and outcome in patients with locally advanced adenocarcinoma of the oesophagus and gastro-oesophageal junction

Background

Raised levels of systemic inflammatory markers are associated with poor survival in patients with cancer. The aim of this study was to assess the prognostic value of markers of systemic inflammation in patients with adenocarcinoma of the oesophagus or gastro-oesophageal junction.

Methods

Data from a consecutive series of patients undergoing transthoracic oesophagectomy following neoadjuvant therapy at a single centre were analysed. Fibrinogen, albumin, C-reactive protein, leucocyte differential and platelet counts were measured before surgery. The upper quartile (75th percentile) was used as a cut-off for dichotomization. Multivariable regression analysis was performed to identify independent prognostic factors.

Results

A series of 199 patients underwent transthoracic oesophagectomy following neoadjuvant therapy. Univariable analysis indicated that reduced median survival was associated with a raised platelet : lymphocyte ratio (158 or above; 25.6 versus 44·4 months for patients with a normal ratio, P = 0·038) and increased fibrinogen levels (4·9 g/l or above; 22·8 versus 59·9 months for those with a normal level, P = 0·005). On multivariable analysis a combination of one or more markers of systemic inflammation was associated with poorer overall survival (hazard ratio 2·12, 95 per cent c.i. 1·20 to 3·74; P = 0·010).

Conclusion

Preoperative markers of systemic inflammation predict poor outcome in patients undergoing curative treatment for locally advanced oesophageal and gastro-oesophageal adenocarcinoma.

Abnormal Epigenetic Modifications in Peripheral T Cells from Patients with Abdominal Aortic Aneurysm Are Correlated with Disease Development

BACKGROUND

Increasing evidence suggests that abdominal aortic aneurysm (AAA) is a T-cell-mediated autoimmune condition. This study investigates the epigenetic modifications that occur in the T cells of AAA patients and evaluates the correlation of these modifications with disease development.

METHODS AND RESULTS

Peripheral T cells were collected from 101 AAA patients and 102 healthy controls (HCs). DNA methylation and histone acetylation levels were measured by ELISA. Methyl-CpG-binding domain, DNA methyltransferase (DNMT) and histone deacetylase (HDAC) mRNA levels were determined by real-time PCR. DNA from the T cells of the AAA patients exhibited significant hypomethylation compared with the HCs (1.6-fold, p < 0.0001). Expression of DNMT1 at the mRNA level in the T cells of the AAA patients was 1.52-fold lower than that of the HCs (p < 0.0001). The extent of DNA methylation in the AAA patients was negatively correlated with the corresponding aortic diameter (r = -0.498, p < 0.0001). H3 (1.59-fold, p < 0.0001) and H3K14 (2.15-fold, p < 0.0001) acetylation levels in the T cells of the AAA patients were higher than those of the HCs, but the HDAC1 mRNA level was 2.33-fold lower than that of the HCs (p < 0.0001).

CONCLUSIONS

DNA methylation and the histone modification status are significantly altered in the T cells of AAA patients. These changes could play a pivotal role in the activation of pathological immune responses and may influence AAA development.

Histone acetylation and histone acetyltransferases show significant alterations in human abdominal aortic aneurysm

Background

Epigenetic modifications may play a relevant role in the pathogenesis of human abdominal aortic aneurysm (AAA). The aim of the study was therefore to investigate histone acetylation and expression of corresponding lysine [K] histone acetyltransferases (KATs) in AAA.

Results

A comparative study of AAA tissue samples (n = 37, open surgical intervention) and healthy aortae (n = 12, trauma surgery) was performed using quantitative PCR, immunohistochemistry (IHC), and Western blot. Expression of the KAT families GNAT (KAT2A, KAT2B), p300/CBP (KAT3A, KAT3B), and MYST (KAT5, KAT6A, KAT6B, KAT7, KAT8) was significantly higher in AAA than in controls (P ≤ 0.019). Highest expression was observed for KAT2B, KAT3A, KAT3B, and KAT6B (P ≤ 0.007). Expression of KAT2B significantly correlated with KAT3A, KAT3B, and KAT6B (r = 0.705, 0.564, and 0.528, respectively, P < 0.001), and KAT6B with KAT3A, KAT3B, and KAT6A (r = 0.407, 0.500, and 0.531, respectively, P < 0.05). Localization of highly expressed KAT2B, KAT3B, and KAT6B was further characterized by immunostaining. Significant correlations were observed between KAT2B with endothelial cells (ECs) (r = 0.486, P < 0.01), KAT3B with T cells and macrophages, (r = 0.421 and r = 0.351, respectively, P < 0.05), KAT6A with intramural ECs (r = 0.541, P < 0.001) and with a contractile phenotype of smooth muscle cells (SMCs) (r = 0.425, P < 0.01), and KAT6B with T cells (r = 0.553, P < 0.001). Furthermore, KAT2B was associated with AAA diameter (r = 0.382, P < 0.05), and KAT3B, KAT6A, and KAT6B correlated negatively with blood urea nitrogen (r = −0.403, −0.408, −0.478, P < 0.05). In addtion, acetylation of the histone substrates H3K9, H3K18 and H3K14 was increased in AAA compared to control aortae.

Conclusions

Our results demonstrate that aberrant epigenetic modifications such as changes in the expression of KATs and acetylation of corresponding histones are present in AAA. These findings may provide new insight in the pathomechanism of AAA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-016-0169-6) contains supplementary material, which is available to authorized users.

Exploring autoimmunity in the pathogenesis of abdominal aortic aneurysms

The abdominal aortic aneurysm (AAA) is a disease process that carries significant morbidity and mortality in the absence of early identification and treatment. While current management includes surveillance and surgical treatment of low- and high-risk aneurysms, respectively, our narrow understanding of the pathophysiology of AAAs limits our ability to more effectively manage and perhaps even prevent the occurrence of this highly morbid disease. Over the past couple of decades, there has been considerable interest in exploring the role of autoimmunity as an etiological component of AAA. This review covers the current literature pertaining to this immunological process, focusing on research that highlights the local and systemic immune components found in both human patients and murine models. A better understanding of the autoimmune mechanisms in the pathogenesis of AAAs can pave the way to novel and improved treatment strategies in this patient population.

B lymphocytes in abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a progressive inflammatory disease of the artery walls. Immune cells, including B lymphocytes, are implicated in the pathogenesis of AAA through interconnected mechanisms. Many studies have shown that compared with normal abdominal aortic tissue, the amount of B lymphocytes that infiltrate the adventitia of AAAs was significantly higher. Activated B lymphocytes promote AAA by producing immunoglobulins, cytokines, and matrix metalloproteinases (MMPs), resulting in the activation of macrophages, mast cells (MCs) and complement pathways. Finally, all of these factors lead to the degradation of collagen and matrix proteins and to aortic wall remodeling, which are hallmarks of AAA. However, few studies focus on the relative function of B cells, and their precise mechanisms in AAA remain unclear. Thus, we summarize the current knowledge on the role of B cells in AAA and offer recommendations for further investigation of preventing the progression of AAA.

Cathepsin K deficiency reduces elastase perfusion-induced abdominal aortic aneurysms in mice

OBJECTIVE

Cathepsin K (CatK) is one of the most potent mammalian elastases. We have previously shown increased expression of CatK in human abdominal aortic aneurysm (AAA) lesions. Whether this protease participates directly in AAA formation, however, remains unknown.

METHODS AND RESULTS

Mouse experimental AAA was induced with aortic perfusion of a porcine pancreatic elastase. Using this experimental model, we demonstrated that absence of CatK prevented AAA formation in mice 14 days postperfusion. CatK deficiency significantly reduced lesion CD4(+) T-cell content, total lesion and medial cell proliferation and apoptosis, medial smooth muscle cell (SMC) loss, elastinolytic CatL and CatS expression, and elastin fragmentation, but it did not affect AAA lesion Mac-3(+) macrophage accumulation or CD31(+) microvessel numbers. In vitro studies revealed that CatK contributed importantly to CD4(+) T-cell proliferation, SMC apoptosis, and other cysteinyl cathepsin and matrix metalloproteinase expression and activities in SMCs and endothelial cells but played negligible roles in microvessel growth and monocyte migration. AAA lesions from CatK-deficient mice showed reduced elastinolytic cathepsin activities compared with those from wild-type control mice.

CONCLUSIONS

This study demonstrates that CatK plays an essential role in AAA formation by promoting T-cell proliferation, vascular SMC apoptosis, and elastin degradation and by affecting vascular cell protease expression and activities.

Deficient CD4 + CD25 + T Regulatory Cell Function in Patients With Abdominal Aortic Aneurysms

Objective— Increasing evidence shows that autoimmune response contributes importantly to pathogenesis of abdominal aortic aneurysm (AAA). This work was aimed to assess the possibly altered function of peripheral CD4 + CD25 + T regulatory cells (Tregs) that might breakdown immunologic self-tolerance in AAA patients.

Methods and Results— Peripheral blood from 22 AAA patients, 11 patients with abdominal aortic atherosclerotic occlusive disease (AOD), and 32 healthy controls (HCs) was analyzed to determine the percentage of CD4 + CD25 + Tregs in the total CD4 + T-cell population and FOXP3 expression by means of flow cytometry. The frequencies of the CD4 + CD25 + Treg population were not significantly different between groups (AAA, 5.69±0.99%; AOD, 5.52±1.13%; HC, 5.88±1.55%; P >0.05). However, the frequency of CD4 + CD25 + FOXP3 + T cells in AAA patients (2.45±0.57%) was significantly lower than that in AOD group (3.41±0.72%; P <0.01) or in HCs (3.69±0.82%; P <0.01). A comparison of FOXP3 mRNA and protein expression revealed significantly lower levels in CD4 + CD25 + Tregs from AAA group than either of other 2 groups ( P <0.01). Suppressive function assay showed that freshly isolated CD4 + CD25 + Tregs from patients with AAA exhibited significantly less suppressive activity than those from AOD patients or HCs ( P <0.01). Mixing cultures with CD4 + CD25 + T cells and CD4 + CD25 − T cells from AAA patients and HCs demonstrated that the primary regulatory defect is due to a dysfunction of CD4 + CD25 + Tregs, and not a resistance of CD4 + CD25 − responder T cells to suppression in AAA patients.

Conclusion— Our data demonstrate a reduced level of FOXP3 expression in peripheral CD4 + CD25 + Tregs and decreased frequency of CD4 + CD25 + FOXP3 + T cells in a cohort of AAA patients enrolled in the study, which leads to a functional deficiency of CD4 + CD25 + Tregs as a whole. This indicates an impaired immunoregulation by Tregs that may contribute to AAA pathogenesis.