Genetic risk factors in inflammatory abdominal aortic aneurysms: polymorphic residue 70 in the HLA-DR B1 gene as a key genetic element

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.

Abdominal aortic diameter and cardiovascular status in patients with idiopathic retroperitoneal fibrosis

Although much debated, an exaggerated inflammatory response to advanced atherosclerosis has been implicated in the pathogenesis of idiopathic retroperitoneal fibrosis (RPF). Clinical presentation, infrarenal abdominal aortic diameter and RPF mass thickness were retrospectively analyzed in 166 patients with idiopathic RPF seen at our referral center between April 1998 and December 2019. Patients were stratified to their infrarenal abdominal aortic diameter at presentation (i.e., non-ectatic [< 25 mm]; ectatic [25-29 mm]; and aneurysmal [≥ 30 mm]) to compare characteristics across groups with an undilated or dilated aorta. Ectatic or aneurysmal aortic dilatation was present in 34% of patients. Most clinical characteristics did not differ across abdominal aortic diameter stratified groups, but RPF mass thickness was greater in patients presenting with aortic aneurysmal dilatation compared to that in patients with an undilated aorta (49.0 mm [IQR 34.0-62.0] vs 32.5 mm [IQR 25.3-47.8]; P < 0.001). A positive linear association was found between aortic diameter on a continuous scale and RPF mass thickness (β 0.32 [95% CI 0.34-0.96]; P < 0.001). This association remained significant after adjusting for age, sex and acute-phase reactant levels (β 0.28 [95% CI 0.15-0.95]; P < 0.01). Treatment success across aortic diameter stratified groups did not differ (P = 0.98). Treatment induced RPF mass regression was not associated with an increase in aortic expansion rate (P = 0.44). Aortic dilatation was prevalent among patients. Infrarenal abdominal aortic diameter was independently associated with RPF mass thickness. Findings support the concept that at least in a subset of patients, RPF may be secondary to advanced atherosclerosis.

Clonally expanded alpha-chain T-cell receptor (TCR) transcripts are present in aneurysmal lesions of patients with Abdominal Aortic Aneurysm (AAA)

Abdominal aortic aneurysm (AAA) is a life-threatening immunological disease responsible for 1 to 2% of all deaths in 65 year old or older individuals. Although mononuclear cell infiltrates have been demonstrated in AAA lesions and autoimmunity may be responsible for the initiation and account for the propagation of the disease, the information available about the pathogenesis of AAA is limited. To examine whether AAA lesions from patients with AAA contain clonally expanded α-chain TCR transcripts, we amplified by the non-palindromic adaptor-PCR (NPA-PCR)/Vα-specific PCR and/or the Vα-specific PCR these α-chain TCR transcripts. The amplified transcripts were cloned and sequenced. Substantial proportions of identical α-chain TCR transcripts were identified in AAA lesions of 4 of 5 patients, demonstrating that clonally expanded T cells are present in these AAA lesions. These results were statistically significant by the bimodal distribution. Three of 5 of these patients were typed by DNA-based HLA-typing and all three expressed DRB1 alleles containing the DRβGln70 amino acid residue that has been demonstrated to be associated with AAA. All three patients exhibited clonally expanded T cells in AAA lesions. Four of the 5 patients with AAA who exhibited clonal expansions of α-chain TCR transcripts, also exhibited clonal expansions of β-chain TCR transcripts in AAA lesions, as we have demonstrated previously (J Immunol 192:4897, 2014). αβ TCR-expressing T cells infiltrating AAA lesions contain T-cell clones which have undergone proliferation and clonal expansion in vivo in response to as yet unidentified specific antigens that may be self or nonself. These results provide additional evidence supporting the hypothesis that AAA is a specific antigen-driven T-cell autoimmune disease.

Investigation of an Immunogenetic Profile in Patients with Abdominal Aortic Aneurysms and Possible Applications in Screening and Surveillance

BACKGROUND

The pathogenesis of atherosclerotic abdominal aortic aneurysms (AAAs) remains not fully understood. Histological analyses confirm chronic adventitial and medial inflammatory cell infiltration, and its pathophysiology involves the upregulation of proteolytic pathways; added to this, genetic factors have been suggested to favor the susceptibility for AAA. The aim of the present study was to analyze the association between genetic polymorphism of the class II human leukocyte antigens (HLAs, HLA-DRB1) with the susceptibility to develop AAA in Mexican patients and to initiate a pilot study of single-nucleotide polymorphisms (SNPs) rs1024611 in the monocyte chemoattractant protein-1 (MCP-1/CCL2) gene to investigate a possible role in the AAA pathogenesis.

METHODS

In a cohort of patients with AAA, HLA molecular typing was completed for DRB1 loci with LABType SSO-One Lambda kit in 39 patients (69% men with a mean age of 72 years) and compared with 99 without the disease (60% men, mean age 65 years) (control group). Genotyping of rs1024611 in the MCP-1 gene was performed using TaqMan predesigned SNP genotyping assays in 27 patients with AAA (63% men, mean age of 71). Gene frequencies (gfs) and genotype frequencies (Gfs) were determined; categorical data were analyzed by nonparametric statistic test at significance level (P < 0.05), and odds ratios (ORs) were calculated using the STATA v14 software and StatCalc software Epi Info™ 7.2.2.2.

RESULTS

Seventy-eight HLA-DRB1 alleles of patients with AAA and 198 from the control group were studied. We observed that the gf of HLA-DRB1*01 was 0.128 in the AAA group compared with 0.05 in the control group (P = 0.03, OR: 2.6, 95% confidence interval [CI]: 1.04-6.5); the gf of HLA-DRB1*16 was 0.115 in the AAA and 0.025 in control group (P = 0.002, OR: 5, 95% CI: 1.6-16.9). The Gf for SNP rs1024611 were 0.51 in the GA genotype, 0.30 in AA, and 0.19 of GG. Four patients with the proinflammatory homozygous genotype GG (80%) were women and younger than patients with other genotypes, and only one had a history of dyslipidemia.

CONCLUSIONS

The dissection and interpretation of an immunogenetic profile in patients with AAA is an active and complex field of research that might assist in a more precise identification of those patients at genetic risk. Our study demonstrated increased frequencies of HLA-DRB1*01 and HLA-DRB1*16 alleles in Mexican patients with AAA compared with an ethnically matched control group.

Genetic polymorphism of HLA-DRB1 alleles in Mexican mestizo patients with abdominal aortic aneurysms

BACKGROUND

Multiple factors are implicated in the etiology and pathogenesis of Abdominal Aortic Aneurysms (AAA). Available literature of genetic studies has previously suggested the possible roles of autoimmunity, genetic predisposition and ethnic susceptibility. Due to the association with autoimmune diseases and proven application in population genetics, we aimed to investigate alleles of the Class II Human Leukocyte Antigens (HLA-DRB1) in the Mexican Mestizo population with aortic aneurysms and determine possible associations with susceptibility.

METHODS

We performed a case Control Study; the HLA molecular typing was completed for DRB1 loci by LabType Sequence-Specific Oligonucleotide (SSO) SSO-OneLambda kit (Applied Biosystems; Thermo Fisher Scientific. Inc.) in the studied individuals. Allele frequencies (af) were determined, associations were assessed by chi square or fisher exact tests at significance level (< 0.05), and Odds Ratios (OR) were calculated using the STATA software version 14.

RESULTS

The genetic polymorphism of HLA-DRB1 of fifty one patients (70% males with a mean age of 71 years) with atherosclerotic or also known as degenerative AAA were compared with 99 unrelated patients (60% males, mean age 65 years) without the disease [Control group (CG)] from the same ethnic group. We examined a total of 102 Class II HLA-DRB1 alleles of AAA patients and 198 from CG. When comparing af, we observed the HLA-DRB1*01 af of 0.139 in the AAA compared to 0.05 in the CG [p = 0.015, OR 3, 95% confidence interval (CI) 1.29-7.08], the HLA-DRB1*16 af were 0.109 in the AAA and 0.025 in CG (p = 0.006, OR 4.7, 95% CI 1.59-13.98).

CONCLUSIONS

Our study confirmed increased frequencies of the alleles HLA-DRB1*01 and HLA-DRB1*16 and their association to the development of AAA in Mexican Mestizo patients. The utility of genetic testing may assist in identifying individuals at genetic risk for the development of this disease in different ethnic groups, who might benefit from earlier ultrasound screening and closer imaging surveillance.

Aneurysmal lesions of patients with abdominal aortic aneurysm contain clonally expanded T cells

Abdominal aortic aneurysm (AAA) is a common disease with often life-threatening consequences. This vascular disorder is responsible for 1-2% of all deaths in men aged 65 years or older. Autoimmunity may be responsible for the pathogenesis of AAA. Although it is well documented that infiltrating T cells are essentially always present in AAA lesions, little is known about their role in the initiation and/or progression of the disease. To determine whether T cells infiltrating AAA lesions contain clonally expanded populations of T cells, we amplified β-chain TCR transcripts by the nonpalindromic adaptor-PCR/Vβ-specific PCR and/or Vβ-specific PCR, followed by cloning and sequencing. We report in this article that aortic abdominal aneurysmal lesions from 8 of 10 patients with AAA contained oligoclonal populations of T cells. Multiple identical copies of β-chain TCR transcripts were identified in these patients. These clonal expansions are statistically significant. These results demonstrate that αβ TCR(+) T lymphocytes infiltrating aneurysmal lesions of patients with AAA have undergone proliferation and clonal expansion in vivo at the site of the aneurysmal lesion, in response to unidentified self- or nonself Ags. This evidence supports the hypothesis that AAA is a specific Ag-driven T cell disease.

Inflammation aggravates disease severity in Marfan syndrome patients

Background

Marfan syndrome (MFS) is a pleiotropic genetic disorder with major features in cardiovascular, ocular and skeletal systems, associated with large clinical variability. Numerous studies reveal an involvement of TGF-β signaling. However, the contribution of tissue inflammation is not addressed so far.

Methodology/Principal Findings

Here we showed that both TGF-β and inflammation are up-regulated in patients with MFS. We analyzed transcriptome-wide gene expression in 55 MFS patients using Affymetrix Human Exon 1.0 ST Array and levels of TGF-β and various cytokines in their plasma. Within our MFS population, increased plasma levels of TGF-β were found especially in MFS patients with aortic root dilatation (124 pg/ml), when compared to MFS patients with normal aorta (10 pg/ml; p = 8×10⁻⁶, 95% CI: 70–159 pg/ml). Interestingly, our microarray data show that increased expression of inflammatory genes was associated with major clinical features within the MFS patients group; namely severity of the aortic root dilatation (HLA-DRB1 and HLA-DRB5 genes; r = 0.56 for both; False Discovery Rate(FDR) = 0%), ocular lens dislocation (RAET1L, CCL19 and HLA-DQB2; Fold Change (FC) = 1.8; 1.4; 1.5, FDR = 0%) and specific skeletal features (HLA-DRB1, HLA-DRB5, GZMK; FC = 8.8, 7.1, 1.3; FDR = 0%). Patients with progressive aortic disease had higher levels of Macrophage Colony Stimulating Factor (M-CSF) in blood. When comparing MFS aortic root vessel wall with non-MFS aortic root, increased numbers of CD4+ T-cells were found in the media (p = 0.02) and increased number of CD8+ T-cells (p = 0.003) in the adventitia of the MFS patients.

Conclusion/Significance

In conclusion, our results imply a modifying role of inflammation in MFS. Inflammation might be a novel therapeutic target in these patients.

New insights into the functional role of the rheumatoid arthritis shared epitope

The shared epitope (SE) - an HLA-DRB1-encoded 5-amino acid sequence motif carried by the vast majority of rheumatoid arthritis (RA) patients - is a risk factor for severe disease. The mechanistic basis of RA-SE association is unknown. This group has previously demonstrated that the SE acts as a signal transduction ligand that activates nitric oxide and reactive oxygen species production. SE-activated signaling depends on cell surface calreticulin, a known innate immunity receptor previously implicated in immune regulation, autoimmunity and angiogenesis. Recent evidence that the SE enhances the polarization of Th17 cells, which is a key mechanism in autoimmunity, is discussed highlighting one of several potential functional effects of the SE in RA.

Coding polymorphisms in the genes of the alternative complement pathway and abdominal aortic aneurysm

Variants in the genes of the alternative complement pathway are associated with risk of numerous inflammatory diseases. Abdominal aortic aneurysm is associated with inflammation and is a common cause of illness and death among European populations. This study tested 49 single nucleotide polymorphisms, including common putatively functional polymorphisms, in the genes of the alternative complement cascade (CFH, CFB, CFD, CFI, properdin, CR1, CR1L, CR2, CD46, vitronectin, C3, C5, C6, C7, C8A, C8B, C8G and C9). The study group were 434 cases with infra-renal aortic diameter ≥30 mm and 378 disease-free controls from two UK centres, all with self-reported European ancestry. There was no evidence for significant association with presence or size of aneurysm following correction for multiple testing. This study suggests that variation in the genes of the alternative pathway is not an important cause of abdominal aortic aneurysm development.

Aortitis and periaortitis in ankylosing spondylitis

Aortic involvement is a potential life-threatening complication of ankylosing spondylitis, usually occurring late in the course of this frequent disease. Inflammatory lesions evolving to fibrosis are primarily localized in the aortic root causing regurgitation, but this process can extend into the left atrium (subaortic bump) involving the mitral valve and the heart conduction system. First, second and third degree atrioventricular blocks are the most common conduction alterations described and they can be temporary. Chronic periaortitis has been described in ankylosing spondylitis patients. This disease is characterized by inflammation evolving to fibrosis and it is localized in the periaortic and peri-iliac retroperitoneum. It causes compressive effects on ureters and venous, arterial and lymphatic vessels. Its treatment employs endoscopic and/or surgical procedures and administration of corticosteroids, even in association with immunosuppressive agents. Both aortitis (with conduction system alterations) and periaortitis should be kept in mind by the physicians because they can significantly influence the prognosis of ankylosing spondylitis patients and they can need a rapid treatment.

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.

Abdominal aortic aneurysm: a review of the genetic basis

BACKGROUND

Abdominal aortic aneurysm (AAA) is a complex disease with a largely unknown pathophysiological background and a strong genetic component. Various studies have tried to link specific genetic variants with AAA.

METHODS

Systematic review of the literature (1947-2009).

RESULTS

A total of 249 studies were identified, 89 of which were eventually deemed relevant to this review. Genetic variants (polymorphisms) in a wide variety of genes, most of which encode proteolytic enzymes and inflammatory molecules, have been associated with AAA development and progression.

CONCLUSION

The genetic basis of AAA remains unknown, and most results from ''candidate-gene'' association studies are contradictory. Further analyses in appropriately powered studies in large, phenotypically well-characterized populations, including genome-wide association studies, are necessary to elucidate the exact genetic contribution to the pathophysiology of AAA.

Symptomatic 7-cm abdominal aortic aneurysm in an otherwise healthy 31-year-old woman

Abdominal aortic aneurysms are rare in young women. We report the case of a 31-year-old woman who underwent open surgical repair of a symptomatic 7-cm abdominal aortic aneurysm (AAA). The patient had no identifiable AAA risk factors. Laboratory and pathological analyses demonstrated a nonspecific inflammatory component.

A new clinicopathological entity of IgG4-related inflammatory abdominal aortic aneurysm

OBJECTIVE

Recently, the relationship between immunoglobulin (Ig)G4 and idiopathic sclerosing lesions has attracted much attention. IgG4-related disease was first described with regard to the pancreas (autoimmune pancreatitis), and has been expanded to various organ systems. We previously reported that inflammatory abdominal aortic aneurysm (IAAA) could be one of the manifestations of IgG4-related disease. In this study, we tried to elucidate the clinical characteristics of IgG4-related IAAA.

METHODS

This study consisted of 23 cases of IAAA and 40 cases of atherosclerotic abdominal aortic aneurysm (AAA). Clinical presentation, laboratory findings, and pathological features were examined. Aneurysms of 13 cases histologically corresponded to IgG4-related IAAA.

RESULTS

Those cases accounted for 5% of all surgical AAAs, and 57% of IAAAs. Compared to non-IgG4-related IAAA, IgG4-related cases were characterized by less frequent association with abdominal or back pain. Serum IgG4 concentrations were significantly elevated in IgG4-related cases. Interestingly, patients with IgG4-related IAAA frequently showed an allergic constitution, such as drug allergy, autoimmune diseases, high serum IgE concentrations, and a high titer of antinuclear antibody. Pathologically, IgG4-related cases were characterized by more significant thickening of the adventitia and more numerous IgG4-positive plasma cell infiltrations. Three non-IgG4-related cases showed aneurysmal rupture at the time of first presentation, whereas no IgG4-related cases showed rupture.

CONCLUSION

Recognizing a new disease entity of IgG4-related IAAA seems important because this was clinically and pathologically different from conventional aAAA and non-IgG4-related IAAA.

Positive association of HLA-DRB1*15 with Dupuytren's disease in Caucasians

Dupuytren's disease (DD) is a permanent nodular condition affecting the palms and digits of the hands, leading to progressive shortening and contractures of the digits often resulting in diminished function and severe deformity. DD is thought to be one of the most common hereditary connective tissue disorders in Caucasians. To elucidate further the aetiology of DD, we compared the HLA-DRB1 phenotype frequencies of DD patients (n=67) against the HLA-DRB1 phenotype frequencies observed in a control population (n=537). HLA-DRB1*15 phenotype frequency was higher in DD positive Caucasoids (37.3%) when compared with control data (20.9%) (corrected P=0.029): we conclude that in Caucasoids of European origin, HLA-DRB1*15 is associated with risk of developing DD.

IgG4-positive plasma cells in inflammatory abdominal aortic aneurysm: the possibility of an aortic manifestation of IgG4-related sclerosing disease

Inflammatory abdominal aortic aneurysm (IAA) is associated with autoimmune disease. However, the precise mechanism of IAA remains unclear. There is increasing evidence that IgG4 is involved in the autoimmune mechanism of various idiopathic sclerosing lesions, including sclerosing pancreatitis and retroperitoneal fibrosis. The present study investigated the hypothesis that the IgG4-related autoimmune reaction is involved in the formation of IAA. The study group consisted of 11 cases of IAA (69.2 +/- 8.59y) and 12 age-matched cases of atherosclerotic abdominal aortic aneurysm (AAA, 69.6 +/- 5.94y), which were used in the previous report. A clinicopathologic examination of these lesions was performed, including histology and immunohistochemistry, in relation to the involvement of IgG4-positive plasma cells in the formation of IAA. No difference in the incidence of risk factors for atherosclerosis was observed between the patients with IAA and AAA. Autoimmune diseases were diagnosed in 2 patients with IAA, including rheumatoid arthritis and polyarteritis nodosa. A patient with IAA had pulmonary fibrosis. In contrast, autoimmune diseases were absent in patients with AAA. However, there was no significant difference in the incidence of autoimmune diseases between the patients with IAA and AAA. Lymphocyte and plasma cell infiltration and fibrosis were significantly more intense and extensive in IAA than in AAA. In addition, lymph follicle formation and vasculitis of small veins and arteries were frequently found in the affected lesions of IAA. Immunohistochemically, IAA showed a significant increase in the number of infiltrating IgG4-positive plasma cells and the incidence of a disrupted follicular dendritic cell network in lymph follicles, in comparison with AAA. These findings suggest that IAA may be an aortic lesion reflecting the presence of IgG4-related sclerosing disease, and not a simple inflammatory aneurysm of the aorta.

The role of human leukocyte antigen genes in the formation of abdominal aortic aneurysms

BACKGROUND

Increasing evidence suggests an autoimmune component to abdominal aortic aneurysm (AAA) formation. This study was conducted to determine if a difference exists in human leukocyte antigen (HLA) allele distribution between patients with AAA and population controls, and between patients with small and large AAA.

METHODS

Patients with known AAA attending the vascular unit were consented for recruitment. HLA-A, HLA-B and HLA-DR was determined by polymerase chain reaction and sequence-specific oligonucleotide probes. The distribution of these alleles in the Northern Ireland general population was obtained from the histocompatibility and immunogenetics database. The chi(2) test was used for statistical analysis with Bonferroni correction.

RESULTS

A total of 241 AAA patients were recruited, with a wide range of aneurysm size. In class I, the most frequent allele families were HLA-A*02 and *01 and HLA-B*07, *08, and *44. In class II, HLA-DRB1*03, *04, *07, and *15 were the most frequent. HLA-A*11 was lower in AAA cases (10.4% vs 15.0%; P = .08), whereas HLA-B*08 was lower in the controls (29.8% vs 36.5%; P = .05) and HLA-DRB1*11 was lower in cases (4.2% vs 8.1%; P = .05). After Bonferroni correction, however, the proportion of allele families was not significantly different in AAA patients compared with the proportion seen in controls. HLA-DRB1*11 and *14 had a lower prevalence in large AAAs (0.9% vs 6.7% [P = .05]; 0.0% vs 5.9% [P = .03]). HLA-A*68 was also lower in large AAA (1.9% vs 11.9%; P = .0075). After Bonferroni correction, however, no difference was demonstrated between small and large aneurysms.

CONCLUSION

This study provides more definitive results on this important subject and has failed to demonstrate the risk association between AAA and these alleles as reported by others. Therefore, the role of these particular genes and the autoimmune component in AAA etiology does not appear to be as crucial as previously proposed.

Abdominal aortic aneurysm is a specific antigen-driven T cell disease

To determine whether monoclonal/oligoclonal T cells are present in abdominal aortic aneurysm (AAA) lesions, we amplified beta-chain T cell receptor (TCR) transcripts from these lesions by the nonpalindromic adaptor (NPA)-polymerase chain reaction (PCR)/V-beta-specific PCR followed by cloning and sequencing. Sequence analysis revealed the presence of substantial proportions of identical beta-chain TCR transcripts in AAA lesions in 9 of 10 patients examined, strongly suggesting the presence of oligoclonal populations of alphabeta TCR+ T cells. We have also shown the presence of oligoclonal populations of gammadelta TCR+ T cells in AAA lesions. Sequence analysis after appropriate PCR amplification and cloning revealed the presence of substantial proportions of identical VgammaI and VgammaII TCR transcripts in 15 of 15 patients examined, and of Vdelta1 and Vdelta2 TCR transcripts in 12 of 12 patients. These clonal expansions were very strong. All these clonal expansions were statistically significant by the binomial distribution. In other studies, we determined that mononuclear cells infiltrating AAA lesions express early- (CD69), intermediate- (CD25, CD38), and late- (CD45RO, HLA class II) activation antigens. These findings suggest that active ongoing inflammation is present in the aortic wall of patients with AAA. These results demonstrate that oligoclonal alphabeta TCR+ and gammadelta TCR+T cells are present in AAA lesions. These oligoclonal T cells have been clonally expanded in vivo in response to yet unidentified antigens. Although the antigenic specificity of these T cells remains to be determined, these T cells may play a significant role in the initiation and/or the propagation of the AAA. It appears that AAA is a specific antigen-driven T cell disease.

Association of fatal aneurysmal subarachnoid hemorrhage with human leukocyte antigens in the Finnish population

Human leukocyte antigens (HLA) have been reported to associate with the risk of aneurysmal subarachnoid hemorrhage (SAH) and poor outcome after SAH. Our aim was to identify HLA antigens that associate with the risk of fatal SAH in the Finnish population. Medical records of 600 cadaveric organ donors were reviewed to find organ donors that succumbed to SAH (n = 232) or brain trauma (n = 151). HLA antigen frequencies in these groups were compared with HLA frequencies in a reference population of 10,000 bone marrow donors. Chi-Square test with Bonferroni correction and multiplicative logistic regression models were used and false positive result probabilities (FPRP) were calculated. Alpha-level was 0.01. HLA-A3 associated with fatal SAH (p = 0.0014, OR 1.3 and 95%CI 1.1-1.6) and HLA-DR7 inversely associated with fatal SAH (p = 0.0040, OR 0.3 and 95%CI 0.2-0.6). HLA-A3 but not HLA-DR7 showed also a positive trend in donors with brain trauma. FPRP was below 0.5 for HLA-A3, but clearly above 0.5 for HLA-DR7. HLA-A3 seems to associate with fatal SAH in the Finnish population. Further studies are needed to reveal the pathobiologic mechanisms for how HLA-A3 associates with the risk of fatal SAH in Finns.

Rethinking the Triggering Inflammatory Processes of Chronic Periaortitis

Chronic periaortitis (CP) is an uncommon inflammatory disease which primarily involves the infrarenal portion of the abdominal aorta. However, CP should be regarded as a generalized disease with three different pathophysiological entities, namely idiopathic retroperitoneal fibrosis (RPF), inflammatory abdominal aortic aneurysm and perianeurysmal RPF. These entities share similar histopathological characteristics and finally will lead to fibrosis of the retroperitoneal space. Beside fibrosis, an infiltrate with variable chronic inflammatory cell is present. The majority of these cells are lymphocytes and macrophages as well as vascular endothelial cells, most of which are HLA-DR-positive. B and T cells are present with a majority of T cells of the T-helper phenotype. Cytokine gene expression analysis shows the presence of interleukin (IL)-1alpha, IL-2, IL-4, interferon-gamma and IL-2 receptors. Adhesion molecules such as E-selectin, intercellular adhesion molecule-1 and the vascular cell adhesion molecule-1 were also found in aortic tissue, and may play a significant role in CP pathophysiology. Although CP pathogenesis remains unknown, an exaggerated inflammatory response to advanced atherosclerosis (ATS) has been postulated to be the main process. Autoimmunity has also been proposed as a contributing factor based on immunohistochemical studies. The suspected allergen may be a component of ceroid, which is elaborated within the atheroma. We review the pathogenesis and the pathophysiology of CP, and its potential links with ATS. Clinically relevant issues are summarized in each section with regard to the current working hypothesis of this complex inflammatory disease.

Abdominal Aortic Aneurysm as a Complex Multifactorial Disease: Interactions of Polymorphisms of Inflammatory Genes, Features of Autoimmunity, and Current Status of MMPs

The role of matrix metalloproteinases (MMPs) in the pathogenesis of abdominal aortic aneurysm (AAA) has focused on the degradation of the extracellular matrix (ECM). The new frontier of MMP biology involves the role of MMPs in releasing cryptic fragments and neoepitopes from the ECM and the impact of MMPs on the regulation of the inflammatory response. The ECM is a complex structure, much more important than an inert scaffold. Both MMP-2 and MMP-9 expose a cryptic epitope that controls angiogenesis. MMPs inhibit angiogenesis through the release of endostatin, endorepellin, arresten, canstatin, and tumstatin. Other breakdown products of the ECM include fragments of fragmin and elastin degradation products (EDPs). In addition, the ECM contains embedded vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-beta). Inflammation is a complex, highly regulated system that involves the identification of injury or infection, response to the injury or infection, repair and healing, and return to normal homeostasis. In some instances, the inflammatory process leads to a pathologic process that is damaging to the host. MMPs play an important role in the control of the inflammatory response through the modification of proinflammatory cytokines, chemokines, and shedding of membrane receptors. Genetic association studies have been performed to help determine the genetic risk associated with certain single nucleotide polymorphisms (SNPs) However, because of the variability in the patient populations and the size of the population, it is difficult to draw any conclusions from these studies. While the etiology of AAA remains unknown, understanding of the inflammatory process and its regulatory points will develop new strategies for the treatment of AAA. Perhaps one difficulty with understanding the pathogenesis of AAA is the lack of precise definition of the phenotype.

Autoimmune aspects of chronic periaortitis

Chronic periaortitis (CP) includes idiopathic retroperitoneal fibrosis, inflammatory abdominal aortic aneurysms and perianeurysmal retroperitoneal fibrosis. These entities are characterised by a fibro-inflammatory tissue which develops around the abdominal aorta and the iliac arteries, and spreads into the surrounding retroperitoneum to entrap adjacent structures such as the ureters. CP often affects patients with advanced atherosclerosis, and several lines of evidence support the view that it could result from a local inflammatory reaction to antigens in the atherosclerotic plaques of the abdominal aorta such as oxidised-low density lipoproteins and ceroid. However, because most CP patients also suffer from constitutional symptoms and show elevated acute-phase reactant levels, positive autoantibodies and, in some cases, autoimmune diseases affecting other organs, CP may also be considered a manifestation of a systemic autoimmune disease. CP is usually diagnosed using computed tomography or magnetic resonance imaging, but retroperitoneal biopsy may also be necessary; positron emission tomography is useful in assessing the full extent of the disease and the metabolic activity of the retroperitoneal tissue. Ureterolysis and aneurysm repair are frequently performed, but the inflammatory and chronic-relapsing nature of the disease often compels the use of medical therapy, which is based on steroids and immunosuppressants.

Evidence for association between the HLA-DQA locus and abdominal aortic aneurysms in the Belgian population: a case control study

BACKGROUND

Chronic inflammation and autoimmunity likely contribute to the pathogenesis of abdominal aortic aneurysms (AAAs). The aim of this study was to investigate the role of autoimmunity in the etiology of AAAs using a genetic association study approach with HLA polymorphisms.

METHODS

HLA-DQA1, -DQB1, -DRB1 and -DRB3-5 alleles were determined in 387 AAA cases (180 Belgian and 207 Canadian) and 426 controls (269 Belgian and 157 Canadian) by a PCR and single-strand oligonucleotide probe hybridization assay.

RESULTS

We observed a potential association with the HLA-DQA1 locus among Belgian males (empirical p = 0.027, asymptotic p = 0.071). Specifically, there was a significant difference in the HLA-DQA1*0102 allele frequencies between AAA cases (67/322 alleles, 20.8%) and controls (44/356 alleles, 12.4%) in Belgian males (empirical p = 0.019, asymptotic p = 0.003). In haplotype analyses, marginally significant association was found between AAA and haplotype HLA-DQA1-DRB1 (p = 0.049 with global score statistics and p = 0.002 with haplotype-specific score statistics).

CONCLUSION

This study showed potential evidence that the HLA-DQA1 locus harbors a genetic risk factor for AAAs suggesting that autoimmunity plays a role in the pathogenesis of AAAs.

Chronic periaortitis and HLA-DRB1*03: another clue to an autoimmune origin

OBJECTIVE

Patients with chronic periaortitis (CP) often show clinical and laboratory findings of a systemic autoimmune disorder. The aim of the present study was to investigate the role of the HLA system in CP.

METHODS

Low-resolution genotyping for HLA-A, HLA-B, and HLA-DRB1 loci and genotyping of TNFA(-238)A/G and TNFA(-308)A/G single nucleotide polymorphisms were performed in 35 consecutive patients with CP and 350 healthy controls.

RESULTS

The HLA-DRB1*03 allele frequency was strikingly higher in patients with CP than in controls (24.28% versus 9.14%; chi(2) = 15.50, P = 0.000084, corrected P [P(corr)] = 0.0012, odds ratio [OR] 3.187, 95% confidence interval [95% CI] 1.74-5.83); the HLA-B*08 allele frequency was also higher in patients than in controls (17.14% versus 6.28%; chi(2)=11.12, P = 0.0008, P(corr) = 0.0269, OR 3.085, 95% CI 1.54-6.16). The A*01 allele frequency was significantly different (P = 0.0463), but the statistical significance was lost after correction for multiple testing (P(corr) = 0.5088). TNFA(-238)A allele and TNFA(-308)A allele frequencies were not significantly different (P = 0.512 and P = 0.445, respectively). Comparison of the main clinical and laboratory findings suggestive of a systemic autoimmune disease (e.g., acute-phase reactants, constitutional symptoms, other autoimmune diseases associated with CP) between the HLA-DRB1*03-positive and the HLA-DRB1*03-negative patients showed that the former group had significantly higher levels of C-reactive protein (P = 0.045) at disease onset, although this difference was not statistically significant after correction for multiple tests (P(corr) = 0.369).

CONCLUSION

The HLA system plays a role in susceptibility to CP. The strong association between CP and HLA-DRB1*03, an allele linked to a wide range of autoimmune conditions, further supports the view that CP may represent a clinical manifestation of an autoimmune disease.

Solitary common iliac artery inflammatory aneurysm in a healthy woman: case report and review of the literature

Inflammatory aneurysms represent only 3-10% of all aortoiliac aneurysms and tend to be more common in men. We report a case of a solitary inflammatory aneurysm of the right common iliac artery in a healthy young woman. The patient presented with persistent abdominal and right flank pain. She had no risk factors for vascular disease, except mild hypertension and a strong family history of aneurysm disease. Her work-up demonstrated a 3.0 cm right common iliac artery aneurysm with intramural thrombus, focal calcification, and perianeurysmal inflammation without evidence of systemic atherosclerosis. There was right hydroureteronephrosis secondary to ureteral compression by the inflammatory aneurysm. She underwent open right common iliac artery aneurysmorraphy with polytetrafluoroethylene interposition graft and concomitant ureterolysis without complication. She remains asymptomatic more than 1 year postoperatively with no evidence of additional aneurysm disease, resolution of her hydroureteronephrosis, and normal kidney function. We report a rare case of a solitary inflammatory aneurysm of the right common iliac artery in a healthy young woman, with a review of the current literature on inflammatory aneurysms.

Results of Endovascular Repair of Inflammatory Abdominal Aortic Aneurysms. A Report from the EUROSTAR Database

OBJECTIVES

To investigate the results following endovascular treatment of patients with inflammatory abdominal aortic aneurysms (IAAA).

DESIGN

Retrospective study based on the EUROSTAR registry.

MATERIAL AND METHODS

Patients included in the EUROSTAR registry with IAAA (n=52, 1.4%) were compared to those having aneurysms without aortic fibrosis (n=3613, 98.6%). The mean follow-up period in patients with IAAA was 23 months (range 1-60). In 11 of the patients detailed information on the effect of endovascular repair and perianeurysmal fibrosis and ureteral entrapment was obtained by a dedicated questionnaire.

RESULTS

Twelve patients (23%) with IAAA had preoperative impairment of renal function and five had known hydronephrosis. Variables that were significantly associated with IAAA included younger age (p<.0001, mean difference 5.9, CI 3.7-7.9) and lower pulmonary risks score (OR 0.38, CI 0.19-0.74). At completion of the endovascular procedure, device stenosis was more frequently observed in patients with IAAA (OR 18.1, CI 3.52-93.0). There were no differences with regard to the rates of mortality, rupture or conversion in patients with IAAA and controls. In the majority, the aneurysm size regressed irrespective of nature of aneurysm. Of the 11 patients with a detailed assessment three had deterioration of renal function and three still had ureteral entrapment during follow-up.

CONCLUSION

Despite persistence of perianeurysmal inflammation in a proportion of patients operative and midterm results of endovascular repair were comparable in the patients with inflammatory and standard AAA.

Chronic periaortitis: a spectrum of diseases

PURPOSE OF REVIEW

Chronic periaortitis includes idiopathic retroperitoneal fibrosis, perianeurysmal retroperitoneal fibrosis, and inflammatory abdominal aortic aneurysms. This review analyses the different aspects of the disease and highlights evolving concepts concerning its pathogenesis, diagnosis, and management.

RECENT FINDINGS

It has recently been reported that asbestos exposure is a major risk factor for idiopathic retroperitoneal fibrosis. An increasing number of studies showing an association with autoimmune diseases clearly support the hypothesis of a close link between autoimmunity and chronic periaortitis. Furthermore, various findings (eg, constitutional symptoms, the involvement of other organs, high acute-phase reactant levels) support the hypothesis that chronic periaortitis may be a manifestation of a systemic disease and challenge the well-known theory of a local immune response to antigens in atherosclerotic plaque. In addition to CT and MRI, which are the diagnostic modalities of choice, positron emission tomography may be useful in monitoring disease activity and response to therapy. Although there is a lack of prospective randomized trials, recent studies have highlighted the role of steroids, immunosuppressive agents, and tamoxifen in the medical treatment of chronic periaortitis.

SUMMARY

Chronic periaortitis is a rare disease with protean manifestations but, if correctly diagnosed, can be successfully managed. It should be approached in the setting of a systemic process, and clinicians must be aware that other organs may be affected. Its clinical course is chronic-relapsing, so a careful follow-up is essential. Further studies are needed to investigate the pathogenetic mechanisms and the most appropriate therapeutic options.

The epidemiology of posttraumatic adult respiratory distress syndrome

BACKGROUND

Although adult respiratory distress syndrome is an important early complication of blunt trauma, the epidemiology and risk factors for its development remain poorly defined. The aims of this study were to determine the prevalence and demographics of this complication in a prospective cohort series of patients admitted to the hospital following injury. We also assessed the contribution of the severity and pattern of the injury to the risk of this complication developing. By identifying factors associated with the highest risk of the development of adult respiratory distress syndrome, we aimed to produce guidelines to facilitate earlier detection.

METHODS

We prospectively studied 7192 patients admitted to a single university hospital, over an eight-year period, for treatment of a traumatic injury. With the exception of patients who had sustained a hip fracture or who had been discharged within seventy-two hours after admission, all patients who required hospital admission following trauma, were older than thirteen years of age, and were a resident within the catchment area were included in the analysis. The prevalence and demographics of posttraumatic adult respiratory distress syndrome were identified for patients who had sustained musculoskeletal, thoracic, abdominal, and head injuries, either in isolation or in combination. The relative risks of this condition developing were calculated according to the injury pattern. Multiple logistic regression analysis was performed to identify the most highly significant predictors of the development of adult respiratory distress syndrome.

RESULTS

Adult respiratory distress syndrome developed in thirty-six (0.5%) of the patients. The prevalence was significantly higher among younger patients (p = 0.002), and 83% of the cases followed high-energy trauma. The prevalence of adult respiratory distress syndrome after isolated thoracic, head, abdominal, or extremity injury was <1%. Patients with injuries to two anatomical regions had a higher prevalence (up to 2.9%), and those with injuries to three anatomical regions had an even higher prevalence (up to 10.2%). Multiple logistic regression analysis showed the Injury Severity Score, the presence of a femoral fracture, the combination of abdominal and extremity injuries, and observations of compromised physiological function on admission each to be an independent predictor of the later development of adult respiratory distress syndrome.

CONCLUSIONS

The prevalence of adult respiratory distress syndrome increases with injury severity and combinations of injuries to more than one anatomical region. We have been able to quantify the importance and relative risks associated with these injuries. The implications of our findings with regard to facilitating early detection of this complication are discussed.

Inflammatory aortic aneurysm is associated with increased incidence of autoimmune disease

OBJECTIVE

It has been suggested that certain genetic risk factors indicative of an autoimmune mechanism can be identified in patients with inflammatory aortic aneurysm (IAA). We therefore investigated whether there was a higher incidence of autoimmune diseases in patients with IAA. Further, we explored risk factors, need for in-hospital resources, and early results of treatment, in a case-control study in a university hospital setting. Material and methods From 1983 to 1994, 520 patients were operated because of abdominal aortic aneurysm (AAA). Thirty-one patients had IAA. Control subjects were matched for aneurysm rupture, emergency or elective hospital admission, and date of operation. Two noninflammatory AAA were included for every IAA.

RESULTS

Of the 31 patients with IAA, 6 patients (19%) had autoimmune disease, compared with none of the control subjects (P =.0017). Two patients had rheumatoid arthritis, 2 patients had systemic lupus erythematosus, 1 had giant cell arteritis, and 1 patient had an undifferentiated seronegative polyarthritis diagnosed as rheumatoid arthritis. Nineteen patients (61%) with IAA had involvement of the duodenum, and 8 patients (26%) had hydronephrosis with ureteral involvement. Operating time was longer in the IAA group, which also had a higher need for blood transfusion. Hospital stay, intensive care unit stay, and 30-day mortality were similar in the two groups.

CONCLUSION

Except for longer operating time and more need for blood transfusions in the IAA group, use of hospital resources was similar after operations to treat IAA or noninflammatory AAA. The study findings indicate an association between IAA and autoimmune disease. This is in accordance with other reports that showed a genetic risk determinant mapped to the human leukocyte antigen (HLA) molecule in these patients. Further research is necessary to explore whether IAA might be a separate entity with a role of antigen binding in the origin of the disease.

Role of HLA-DR in the pathogenesis of abdominal aortic aneurysm

OBJECTIVE

to establish a possible role for autoimmunity in the aetiology of abdominal aortic aneurysm (AAA) by examining human leukocyte antigen class II (HLA-II) immune response genes.

MATERIALS AND METHODS

HLA-II typing was performed in a series of 72 AAA patients and a control group of 380 healthy subjects.

RESULTS

a higher incidence of the allele subtype HLA-DR B1*0401 was detected in the AAA group with respect to the control group (12.5 vs 5.2%; p = 0.02, OR 2.59). In contrast, the HLA-DR B1*01 allele tended to behave as a protective factor for AAA (12.5% AAA vs 21.3% controls; p = 0.09, OR 0.5).

CONCLUSIONS

the association observed here between HLA-DR B1*0401 and HLA-DR B1*01 and unspecific AAA is similar to that reported in several autoimmune diseases. This similarity suggests an essential role for autoimmune factors in the formation of the AAA.

Human leukocyte antigen class II immune response genes, female gender, and cigarette smoking as risk and modulating factors in abdominal aortic aneurysms

OBJECTIVE

Aortic inflammation and the genes that regulate the immune response play an important role in abdominal aortic aneurysm pathogenesis. However, the modulating effects of such genetic and other environmental factors on the severity on aneurysm inflammation is not known. The objective of this study was to determine the influence of the human leukocyte antigen (HLA) class II genes, gender, and environmental factors on degree of abdominal aortic aneurysm tissue inflammation.

METHODS

Aneurysm specimens were obtained at the time of operation from 96 consecutive patients who underwent abdominal aortic aneurysm repair and were graded for degree of histologic inflammation. Multivariate analysis was used to determine the association of genetic and environmental factors with degree of inflammation and to determine the HLA-associated disease risk for aneurysm.

RESULTS

Active cigarette smoking and female gender were independently associated with high-grade tissue inflammation identified histologically (odds ratio [OR], confidence interval [CI]: 5.6, 1.6 to 19.3; and 6.0, 1.4 to 26.2, respectively), and a specific HLA allele (DR B1(*)01) was inversely associated with inflammation (OR, CI: 0.2, 0.04 to 0.7). Overall, the HLA-DR B1(*)02 and B1(*)04 alleles were significantly associated with disease risk, more than doubling risk for abdominal aortic aneurysm (OR, CI: 2.5, 1.4 to 4.3; and 2.1, 1.2 to 3.7, respectively).

CONCLUSION

Active cigarette smoking and female gender are significant disease-modulating factors associated with increased abdominal aortic aneurysm inflammation. In addition, the HLA class II immune response genes possess both disease modulating and disease risk properties, which may be useful in early aneurysm detection and surveillance.

Genetic similarity in inflammatory and degenerative abdominal aortic aneurysms: a study of human leukocyte antigen class II disease risk genes

PURPOSE

Clinically, abdominal aortic aneurysms (AAAs) display a spectrum of inflammation that extends from apparently noninflamed (degenerative) AAAs to the classic inflammatory variant. Genes encoded in the human leukocyte antigen (HLA) region are important in the development of both variants of AAA; however, their role in progression to the inflammatory variant is unknown. The purpose of this study was to compare HLA class II genes in patients with degenerative versus classic inflammatory AAAs and to quantify their impact as disease risk factors.

METHODS

Genotypes of the 12 major alleles of the HLA-DR B1 locus were determined in patients with degenerative (102) and inflammatory (40) AAAs who were compared with controls (118). Univariate and multivariate logistic regression analyses were used to determine allele distributions and to quantify disease risk.

RESULTS

Distribution of the HLA-DR B1 alleles was nonrandom and similar in both degenerative and inflammatory AAA groups compared with controls. The B1*02 and B1*04 alleles were enhanced in both degenerative (39.2% vs. 25.4%, P =.03; and 35.3% vs. 24.6%, P =.08 respectively) and inflammatory (47.5% vs. 25.4%, P =.01; and 32.5% vs. 24.6%, P =.09, respectively) AAAs compared with controls. The B1*02 and B1*04 alleles were associated with risk for both degenerative (odds ratio [OR] 2.2; 95% CI, 1.2-4.0; and OR 2.0; 95% CI, 1.1-3.7, respectively) and inflammatory AAAs (OR 3.7; 95% CI, 1.8-8.6; and OR 2.5; 95% CI, 1.1-6.1).

CONCLUSION

This study demonstrates that identical HLA alleles function as genetic risk factors for both inflammatory and degenerative AAAs. These results support the concept of a common, immune-mediated pathogenesis for AAAs that may be modulated by HLA-independent factors.

Aortic aneurysm and dissection are not associated with an increased risk for giant cell arteritis/ polymyalgia rheumatica

It has recently been claimed that giant cell arteritis (GCA) is associated with a markedly increased risk of aortic aneurysm formation or rupture. In the present study, the opposite approach was taken, by looking for the incidence of GCA and polymyalgia rheumatica (PMR) in patients with aortic aneurysm, aortic dissection, or both (AA/D). The records of 315 consecutive patients admitted with the diagnosis of AA/D were reviewed. In addition, follow up information was obtained in 82 patients by examination in the outpatient clinic. After careful examination and assessment of clinical and laboratory data, it was found that none of the 82 patients who survived hospitalisation and were available for examination had GCA or PMR. Moreover, review of the retrospective data available from hospital records of the total consecutive 315 patients with AA/D failed to find any patient with a diagnosis of GCA/PMR. In conclusion, the present study did not find an increased prevalence of GCA/PMR among a cohort of Israeli patients with AA/D. Therefore, it is suggested that a thorough investigation aiming to diagnose GCA/PMR is not cost effective in most of the elderly patients presenting with AA/D.

Inflammatory abdominal aortic aneurysm: A postoperative course of retroperitoneal fibrosis

PURPOSE

The long-term outcome and the development of retroperitoneal fibrosis after surgery on an inflammatory aortic aneurysm was studied.

METHODS

Between 1989 and 1997, 1035 patients underwent surgery for an abdominal aneurysm, 42 of whom (4.1%) had typical signs of inflammation. All patients underwent computed tomography (CT) scans before operation, and 26 patients were followed up with a CT scan after a median of 36 months (range, 10 to 91 months).

RESULTS

The inflammatory layer resolved completely in only 23% of the patients. One patient had marked progression, 35% of patients showed improvement, and the remaining patients had no change, compared with the preoperative findings. Although clinical symptoms subsided in 90% of patients, in five cases an involvement of the ureter or intestine that did not exist at the time of operation developed. Although ureteral involvement to the inflammation tends to subside after surgery, persisting fibrosis was associated with ureteral entrapment in 30% of these cases and resulted in renal compromise in 49%. Hydronephrosis that was not present at the time of operation was found in 19% of patients, despite improving or stable inflammatory lesions.

CONCLUSION

This case-control study supports the findings that retroperitoneal fibrosis persists longer than previously thought, and progression might even occur. Formerly uninvolved organs might become included in the process despite regression of the layer, leading to considerable problems if the condition is not treated in institutions familiar with this complex disease. We advocate a moderated follow-up scheme, as in the case of ordinary abdominal aortic aneurysm, and the need for long-term surveillance of inflammatory aneurysms.