Activated adaptive immune system in dissected bicuspid aortic valve aortas: trigger for dissection?

Background/Introduction

Bicuspid aortic valve (BAV) is associated with ascending aorta aneurysms and dissections. Presently, genetic factors and pathological flow patterns are considered responsible for aneurysm formation in BAV. Despite, indication for preventive surgery is presently only defined by vessel diameter which is poor marker for dissection, as it does not take other processes responsible for the vulnerability of the aorta into account.

Purpose

Inflammation is not considered a player in BAV aortopathy. We introduce a quantitative immunohistochemistry (IHC) approach to sensitively look at the potential role of both the innate and adaptive immune system in BAV aortopathy.

Methods

Dilated (n=8), non-dilated (n=14) and dissected (n=4) BAV ascending aortas were collected during surgery or from post-mortem donors. Median time from symptoms to surgery for dissections was just over 4 hours. Tissue was stained with a novel 8-colour IHC technique allowing for simultaneous visualization of 6 markers per slide, completed with DAPI nuclear counter-stain and elastin fiber autofluorescence. One panel focused on the adaptive immune system (identifying B cells and classic dendritic cells type 2 (cDC2s) and phenotyping T cells), and the other on the innate immune system (assessing macrophage polarization and neutrophil extravasation). All cells were identified and comprehensively phenotyped using automated quantitative analysis.

Results

Aneurysm formation was associated with an organized and consistent increase of lymphocytes in the adventitia. B cell follicles and helper T cell expansion were identified, suggestive of a targeted adaptive immune response (Fig. 1a). Only dissected aortas showed a statistically significant increase of helper T (p=0.3) and cDC2s (p=0.3) in the media, when compared to non-dilated and dilated samples (Fig. 1b). The short time between dissection symptoms and surgery suggests these cells were present before the dissection occurred. Furthermore, aneurysms and dissections are associated with a shift in macrophage phenotype to the more aggressive M1-like subset. In summary, we found that a progression of aggressive immune cells in the adventitia and media was correlated to a progression in disease state; from normal to dilated to dissected.

Conclusions

Aorta dilatation in patients with BAV is associated with an expansion of B and helper T cells in the adventitial compartment without changes in the media. This result might indicate an antigen-driven adaptive immune response. Only dissections show an increase in helper T cells and cDC2s in the media, together with polarization of macrophages to a more M1-like phenotype. We hypothesize that antigen-specific helper T cells expand in the adventitia, migrate to the media, and then potentiate macrophages which can eventually lead to tissue degeneration. These associations could shine light on the final step in the deterioration of the aorta towards a dissection.

Figure 1. Microscopy results

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): TTW-NWO open technology grant (STW-14716), ERC-2014-StG-336454-CoNQUeST

Angiosarcoma of the Descending Aorta, Diagnostic Difficulties

Introduction

Primary angiosarcomas of the aorta are rare and because of their non-specific presentation, the initial diagnosis is often very difficult.

Report

A 66 year old woman, initially suffering from night sweats and general malaise, is presented. A computerized tomography (CT) scan was performed which showed a filling defect of the descending aorta. This defect later caused embolic occlusion of the celiac vessels. The patient underwent surgical resection of the filling defect of the descending aorta and an embolectomy of the celiac vessels. The defect was histopathologically diagnosed as an angiosarcoma. The clinical presentation, diagnostic pitfalls, histopathological diagnosis, and the therapeutic management are discussed.

Discussion

In this case report, the importance of carefully diagnosing an angiosarcoma is highlighted as the consequences could be rapid metastasization or embolization.

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An angiosarcoma of the descending aorta was diagnosed, which is a rare malignancy.

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This malignancy is very hard to diagnose therefore long-term survival is uncertain.

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This malignancy is very aggressive for both local and distant recurrence.

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This case report reflects the difficulty in diagnosing this malignancy.

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It also shows the rapid progression of this disease.

Aortic root replacement with human tissue valves in aortic valve endocarditis

OBJECTIVE

Aortic allograft and pulmonary autograft aortic root replacement in native and prosthetic aortic valve endocarditis are evaluated and risk factors for hospital death are assessed by univariate risk factor analysis.

METHODS

From April 1989 to May 1996, 59 patients with aortic valve endocarditis (27 native; 32 prosthetic) underwent aortic root replacement with a human tissue valve. Mean age was 53.4 +/- 12.3 years; 46 patients (78%) were male. The mean preoperative NYHA functional class was 3.4. The predominant infective organisms were streptococci (30%) in the native valve group and staphylococci (30%) in the prosthetic valve group. In native valve endocarditis, valve destruction (32%) was the predominant finding. Abscesses, either annular (29%) or subannular (36%) and valve dehiscence (36%) were the most common findings in patients with prosthetic valve endocarditis. Partial or total ventriculo-aortic discontinuity (20%) and aortico-mitral discontinuity (27%) were other important operative observations. A cryopreserved allograft was used in 53 patients (89.5%), the pulmonary autograft (Ross procedure) in 5 patients (8.5%), and a fresh antibiotic sterilized allograft root in one patient (2%). Mean aortic cross-clamp time was 131 +/- 32 min. In active native and prosthetic valve endocarditis, intravenous antibiotics were continued for at least 6 weeks, monitored by serial CRP measurements.

RESULTS

Hospital mortality was 8.5% (n = 5; 70% CL: 4.9-12.1%). Univariate risk factors for hospital mortality were age (P = 0.001), preoperative New York Heart Association functional class (P = 0.001), pre- (P = 0.001) and postoperative (P = 0.001) renal insufficiency. Major complications were allograft failure (n = 1; 2%), technical failure (n = 1; 2%) and false aneurysm formation at the proximal suture line (n = 1; 2%). Follow-up was complete, mean 33.1 +/- 20.1 months. Two late deaths occurred. Actuarial five year survival was 88.8% (70% CL: 80.0-97.5%); actuarial five year freedom from recurrent endocarditis was 98.1% (70% CL: 94.5-100%).

CONCLUSION

Allograft aortic root replacement is a valuable technique in the life threatening situations both of native and prosthetic aortic valve endocarditis with involvement of the annular and peri-annular region.

Pulmonary function before surgery for pectus excavatum and at long-term follow-up

Pulmonary function tests were performed before surgery on 152 patients who were operated on for pectus excavatum between 1970 and 1987 and at long-term follow-up to assess the degree of impairment and to investigate any changes caused by surgical correction. The mean age at surgery was 15.3 +/- 5.5 years. Pulmonary function was found to be restricted preoperatively. Multivariate analysis showed that preoperative pulmonary function was not related to age, the severity of the deformity at physical examination, or to pulmonary complaints. Only the patients with obstructive disease showed significantly more pulmonary complaints (p = 0.042). The total lung capacity (TLC) and inspiratory vital capacity (IVC) were significantly related to the age-corrected (delta) anteroposterior diameter of the chest (lower vertebral index [LVI]) (p = 0.0001). At follow-up (mean, 8.1 +/- 3.6 years), the restriction of pulmonary function was increased despite improvement in the symptoms of most patients and despite a significant increase in the anteroposterior diameter of the chest (p = 0.0001): the TLC was decreased from 83.7 percent predicted (pred) preoperatively to 73.8 percent pred (p = 0.0001) and the IVC from 78.3 percent pred to 70.7 percent pred (p = 0.0001). The surgical results were satisfactory in 83.6 percent. No relation was found between the changes in pulmonary function measured at follow-up and the surgical results. Only the age at surgery and the changes in the TLC and IVC at follow-up were significantly related (p = 0.0036, 0.0043, respectively), although the correlation coefficients were low (r = 27 percent and 28 percent, respectively). The reduction in lung function at follow-up was most pronounced in the patients who had the least functional impairment (TLC > 75 percent pred) preoperatively. No correlation was found between the changes in the pulmonary function test results at follow-up and follow-up interval, preoperative delta LVI, and the change in delta LVI at follow-up.