Irene Hinterseher

Genes and abdominal aortic aneurysm.

Abdominal aortic aneurysm (AAA) is a multifactorial disease with a strong genetic component. Since the first candidate gene studies were published 20 years ago, approximately 100 genetic association studies using single nucleotide polymorphisms (SNPs) in biologically relevant genes have been reported on AAA. These studies investigated SNPs in genes of the extracellular matrix, the cardiovascular system, the immune system, and signaling pathways. Very few studies were large enough to draw firm conclusions and very few results could be replicated in another sample set. The more recent unbiased approaches are family-based DNA linkage studies and genome-wide genetic association studies, which have the potential of identifying the genetic basis for AAA, only when appropriately powered and well-characterized large AAA cohorts are used. SNPs associated with AAA have already been identified in these large multicenter studies. One significant association was of a variant in a gene called contactin-3, which is located on chromosome 3p12.3. However, two follow-up studies could not replicate this association. Two other SNPs, which are located on chromosome 9p21 and 9q33, were replicated in other samples. The two genes with the strongest supporting evidence of contribution to the genetic risk for AAA are the CDKN2BAS gene, also known as ANRIL, which encodes an antisense ribonucleic acid that regulates expression of the cyclin-dependent kinase inhibitors CDKN2A and CDKN2B, and DAB2IP, which encodes an inhibitor of cell growth and survival. Functional studies are now needed to establish the mechanisms by which these genes contribute toward AAA pathogenesis.

MicroRNA expression signature in human abdominal aortic aneurysms

BackgroundAbdominal aortic aneurysm (AAA) is a dilatation of the aorta affecting most frequently elderly men. Histologically AAAs are characterized by inflammation, vascular smooth muscle cell apoptosis, and extracellular matrix degradation. The mechanisms of AAA formation, progression, and rupture are currently poorly understood. A previous mRNA expression study revealed a large number of differentially expressed genes between AAA and non-aneurysmal control aortas. MicroRNAs (miRNAs), small non-coding RNAs that are post-transcriptional regulators of gene expression, could provide a mechanism for the differential expression of genes in AAA.MethodsTo determine differences in miRNA levels between AAA (n = 5) and control (n = 5) infrarenal aortic tissues, a microarray study was carried out. Results were adjusted using Benjamini-Hochberg correction (adjusted p < 0.05). Real-time quantitative RT-PCR (qRT-PCR) assays with an independent set of 36 AAA and seven control tissues were used for validation. Potential gene targets were retrieved from miRNA target prediction databases Pictar, TargetScan, and MiRTarget2. Networks from the target gene set were generated and examined using the network analysis programs, CytoScape® and Ingenuity Pathway Core Analysis®.ResultsA microarray study identified eight miRNAs with significantly different expression levels between AAA and controls (adjusted p < 0.05). Real-time qRT-PCR assays validated the findings for five of the eight miRNAs. A total of 222 predicted miRNA target genes known to be differentially expressed in AAA based on a prior mRNA microarray study were identified. Bioinformatic analyses revealed that several target genes are involved in apoptosis and activation of T cells.ConclusionsOur genome-wide approach revealed several differentially expressed miRNAs in human AAA tissue suggesting that miRNAs play a role in AAA pathogenesis.

Prevalence and treatment of bleeding complications in chronic pancreatitis

ObjectivesAs spontaneous major haemorrhage in patients with chronic pancreatitis is rare, limited data have been reported, and no evidence-based guidelines are currently available regarding the optimal treatment modality.Patients and methodsWe report our experience with 36 patients with severe bleeding complications from a series of 541 patients presenting with chronic pancreatitis (representing a prevalence of 6.7% of admitted patients), treated in one surgical department over a period of 9.5 years, with a median follow-up of 4.1 years.ResultsHaemorrhage was indirectly related to chronic pancreatitis in eight patients (22.2%) with ulcer or variceal bleeding. Three patients (8.4%) demonstrated spleen infarction or rupture. The most common causes of major haemorrhage were pseudoaneurysms in 25 patients (69.4%). Nine of them were treated with primary embolization. Sixteen patients with pseudoaneurysms underwent surgery. The only mortalities (8.3%) observed were from bleeding-associated complications of pseudoaneurysms. Two patients died after surgery, and one after primary embolization. We observed a higher re-bleeding rate after surgery (25% vs 11% after embolization). The presence of haemorrhagic shock, and the amount of blood transfused, were significant determinants of hospital mortality. Patient age, pseudoaneurysm location, and treatment modality had no significant influence on mortality.ConclusionsAny haemodynamically stable patient with haemorrhage due to arterial pseudoaneurysms should undergo angiography with embolization when technically possible. If there are no other pancreas-related indications for surgery, embolization remains the definitive treatment. If embolization is not available or has failed, surgery is indicated, although perioperative morbidity will be higher.

Novel pathways in the pathobiology of human abdominal aortic aneurysms

Objectives: Abdominal aortic aneurysm (AAA), a dilatation of the infrarenal aorta, typically affects males >65 years. The pathobiological mechanisms of human AAA are poorly understood. The goal of this study was to identify novel pathways involved in the development of AAAs. Methods: A custom-designed ‘AAA-chip’ was used to assay 43 of the differentially expressed genes identified in a previously published microarray study between AAA (n = 15) and control (n = 15) infrarenal abdominal aorta. Protein analyses were performed on selected genes. Results: Altogether 38 of the 43 genes on the ‘AAA-chip’ showed significantly different expression. Novel validated genes in AAA pathobiology included ADCY7, ARL4C, BLNK, FOSB, GATM, LYZ, MFGE8, PRUNE2, PTPRC, SMTN, TMODI and TPM2. These genes represent a wide range of biological functions, such as calcium signaling, development and differentiation, as well as cell adhesion not previously implicated in AAA pathobiology. Protein analyses for GATM, CD4, CXCR4, BLNK, PLEK, LYZ, FOSB, DUSP6, ITGA5 and PTPRC confirmed the mRNA findings. Conclusion: The results provide new directions for future research into AAA pathogenesis to study the role of novel genes confirmed here. New treatments and diagnostic tools for AAA could potentially be identified by studying these novel pathways.

Role of Complement Cascade in Abdominal Aortic Aneurysms

Objective—The goal of this study was to investigate the role of complement cascade genes in the pathobiology of human abdominal aortic aneurysms (AAAs). Methods and Results—Results of a genome-wide microarray expression profiling revealed 3274 differentially expressed genes between aneurysmal and control aortic tissue. Interestingly, 13 genes in the complement cascade were significantly differentially expressed between AAA and the controls. In silico analysis of the promoters of the 13 complement cascade genes showed enrichment for transcription factor binding sites for signal transducer and activator of transcription (STAT)5A. Chromatin-immunoprecipitation experiments demonstrated binding of transcription factor STAT5A to the promoters of the majority of the complement cascade genes. Immunohistochemical analysis showed strong staining for C2 in AAA tissues. Conclusion—These results provide strong evidence that the complement cascade plays a role in human AAA. Based on our microarray studies, the pathway is activated in AAA, particularly via the lectin and classical pathways. The overrepresented binding sites of transcription factor STAT5A in the complement cascade gene promoters suggest a role for STAT5A in the coordinated regulation of complement cascade gene expression.

Novel Genetic Mechanisms for Aortic Aneurysms

Aortic aneurysms occur in the thoracic and abdominal sections of the aorta and are a deadly late-age-at-onset disease with complex pathobiology. Currently, the number of published genome-wide analyses including microarray-based expression profiling, DNA linkage studies, and genetic association studies is still limited and it is difficult to make generalizations about the disease pathogenesis or genetic risk factors contributing to aortic aneurysms, but it appears that thoracic aortic aneurysms differ in many ways from abdominal aortic aneurysms. Characterization of diseases at the molecular level is likely to lead to more accurate diagnoses and the use of “genomic nosology” of disease. The biggest future challenge will be to translate the genomic information to the clinic and improve our understanding of the disease processes, help us to develop better diagnostic tools, and lead to the design of new ways to manage aortic aneurysms in the era of personalized medicine.

Differential gene expression in the proximal neck of human abdominal aortic aneurysm

OBJECTIVE Abdominal aortic aneurysm (AAA) represents a common cause of morbidity and mortality in elderly populations but the mechanisms involved in AAA formation remain incompletely understood. Previous human studies have focused on biopsies obtained from the center of the AAA however it is likely that pathological changes also occur in relatively normal appearing aorta away from the site of main dilatation. The aim of this study was to assess the gene expression profile of biopsies obtained from the neck of human AAAs. METHODS We performed a microarray study of aortic neck specimens obtained from 14 patients with AAA and 8 control aortic specimens obtained from organ donors. Two-fold differentially expressed genes were identified with correction for multiple testing. Mechanisms represented by differentially expressed genes were identified using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Some of the differentially expressed genes were validated by quantitative real-time PCR (qPCR) and immunohistochemistry. RESULTS We identified 1047 differentially expressed genes in AAA necks. The KEGG analysis revealed marked upregulation of genes related to immunity. These pathways included cytokine-cytokine receptor interaction (P = 8.67*10(-12)), chemokine signaling pathway (P = 5.76*10(-07)), and antigen processing and presentation (P = 4.00*10(-04)). Examples of differentially expressed genes validated by qPCR included the T-cells marker CD44 (2.16-fold upregulated, P = 0.008) and the B-cells marker CD19 (3.14-fold upregulated, P = 0.029). The presence of B-cells in AAA necks was confirmed by immunohistochemistry. CONCLUSIONS The role of immunity in AAA is controversial. This study suggests that immune pathways are also upregulated within the undilated aorta proximal to an AAA.

Presence of Borrelia burgdorferi sensu lato antibodies in the serum of patients with abdominal aortic aneurysms

Infectious agents are likely to play a role in the pathogenesis of chronic inflammatory diseases, including abdominal aortic aneurysms (AAAs). The goal of this study was to determine if Borrelia burgdorferi sensu lato (sl), a microorganism responsible for Lyme disease, is involved in the etiology of AAAs. The presence of serum antibodies against B. burgdorferi sl was measured with enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blotting in 96 AAA and 108 peripheral artery disease (PAD) patients. Polymerase chain reaction (PCR) was used for the detection of Borrelia-specific DNA in the aneurysm wall. Among AAA patients 34% and among PAD patients 16% were seropositive for B. burgdorferi sl antibodies (Fisher’s exact test, p = 0.003; odds ratio [OR] 2.79; 95% confidence interval [CI] 1.37–5.85). In the German general population, 3–17% are seropositive for Borrelia antibodies. No Borrelia DNA was detected in the aneurysm wall. Our findings suggest a relationship between AAAs and B. burgdorferi sl. We hypothesize that the underlying mechanism for B. burgdorferi sl in AAA formation is similar to that by the spirochete Treponema pallidum; alternatively, AAAs could develop due to induced autoimmunity via molecular mimicry due to similarities between some of the B. burgdorferi sl proteins and aortic proteins.

Long-Term Quality of Life of Abdominal Aortic Aneurysm Patients Under Surveillance or After Operative Treatment

BACKGROUND The objective of this study was to determine the long-term quality of life (QOL) in patients with an abdominal aortic aneurysm (AAA) undergoing surveillance or after operative treatment. METHODS 249 patients with AAAs completed the WHO Quality of Life-BREF (WHOQOL-BREF) test and Short Form (36) Health Survey (SF-36) survey: 78 patients with small AAAs under surveillance, 26 after ruptured AAAs (rAAAs), 47 after endovascular aneurysm repair (EVAR), and 98 after elective open repair. The results were compared with WHOQOL-BREF and SF-36 standard values from a matched German population using the Students 2-tailed t-test. RESULTS Long-term results of the WHOQOL-BREF test showed that patients undergoing AAA surveillance had a significantly lower physical QOL (P = 0.04). Patients after EVAR or open repair rated their environmental QOL significantly higher than the age- and sex-matched general population (open repair: P = 0.006; EVAR: P < 0.001). Patients with rAAAs had the same QOL as the matched German population. Long-term results of the QOL SF-36 showed that patients undergoing AAA surveillance rated their QOL significantly lower in the subgroup of role-physical (P = 0.02) and role-emotional (P = 0.003). Patients with rAAAs rated lower scores for role-physical (P = 0.02) and had more bodily pain (P = 0.02). Patients who underwent elective open repair had the same high QOL as the matched German population, whereas patients who underwent EVAR reported significant improvement in vitality (P = 0.002) and mental health (P = 0.03) compared with the matched German population. CONCLUSIONS Based on measurements from 2 independent QOL tests, the well-established operative treatment of AAAs provided patients with a QOL comparable to that of a matched German population. The electively treated AAA groups rated environmental QOL factors significantly higher than the control group. The impaired physical and emotional QOL of the AAA group under surveillance suggests that more intense patient education could be beneficial.

Compression of the left renal artery and celiac trunk by diaphragmatic crura

Symptomatic compression of the celiac trunk by crura of the diaphragm is a rare disorder. Even more infrequent external compression of renal arteries is found. Although the indication for surgical therapy is controversially discussed in the literature for celiac artery compression syndrome, it is unequivocally for renal artery entrapment. We present the case of a young woman who was assigned to our hospital with arterial hypertension and stenosis of the left renal artery. After percutaneous transluminal angioplasty was performed, immediate recoil occurred. Therefore, the suspicion of entrapment by diaphragmatic crura was expressed. Additionally performed diagnostic procedures including computed tomography (CT)-angiography verified our suspicion. Surgical decompression of both vessels was successfully performed.