AB1424 EXPLORING AUTOIMMUNE ANTIBODIES AND THE HISTOLOGICAL CHARACTERISTIC OF VESSEL WALL INFLAMMATION IN ABDOMINAL AORTIC ANEURYSMS (2024)

Abstract

Background: Aortic aneurysms are the most common dilations in the human body, which occur primarily in the abdominal aorta section. The disease affects approximately 1-5% of the adult population. Its main risk factors include age over 65 years, smoking, and male gender. The exact pathomechanism of the disease is still unknown, but the importance of degenerative, congenital, mechanical, and inflammatory factors is emerging. The pathological role of arteriosclerosis is primarily assumed to be behind the degenerative processes that develop in the vessel wall. In addition, systemic autoimmune processes involved in the etiology of aortic aneurysms and the consequent local inflammatory mechanisms are particularly important. The incidence of aortic aneurysms arising from large-vessel vasculitis in the form of subclinical vessel wall inflammation is unknown.

Objectives: To investigate the pathomechanism of the inflammatory and autoimmune processes involved in the development of aortic aneurysms by determining immunoserological and aortic wall histological parameters in patients who have undergone open aneurysm repair surgery.

Methods: An aneurysm biobank was created for this purpose. Tissue samples from patients are stored in Semmelweis University Heart and Vascular Center, Department of Vascular and Endovascular Surgery Biobank. From the patient’s samples of the aortic wall, thrombus that fill the lumen of the affected vessel, blood, saliva, urine, and anal smear are stored in the biobank. In addition to the general routine blood test, immunoserological parameters were also tested in all patients before open aneurysm surgery. Samples taken from the vessel walls of all patients during open aortic aneurysm surgery underwent detailed histological analysis at the 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, to determine the degree of inflammation. There was no known systemic autoimmune disease in the medical history of the patients.

Results: 56 patients were included, comprising 13 women and 43 men, with a mean age of 68.65 ± 6.71 years. A total of 33 of 56 patients (59%) showed antibody positivity (AB) (female/male ratio:7/26), while 23 patients (41%) (female/male ratio: 7/16) did not exhibit any AB positivity. Analyzing the AB distribution, the most common antibodies are Anti-cardiolipin AB 15,1%, anti-beta-2-glycoprotein AB 9,4%, Lupus Anticoagulant 32,7%, Antinuclear antibody 25%, anti-cytoplasmic AB 12,5% and Rheumatoid Factor Ig M 12,7%. The histopathological examination categorized patients into three groups based on the degree of inflammation observed in the tissue samples. Of 25 patients with abdominal aortic aneurysm open repair, 92% of patients exhibited vessel wall inflammation, with only two exceptions showing no signs of inflammation. 14 patients had well-defined inflammation, while 9 patients had subclinical inflammation. In the well-defined inflammation group, characterized by prominent inflammation in the tissue samples, the mean CRP level was 15.52 mg/l, with an interquartile range (IQR) of 5.12-25.92 mg/l. The subclinical inflammation group had a mean CRP level of 4.81 mg/l, with an IQR of 2.31-7.31 mg/l. Patients without histopathological signs of inflammation had a mean CRP level of 3.7 mg/l, with an IQR of 2.71-4.69 mg/l.

Conclusion: These findings provided that Immunoserological positivity may play a role in the pathogenesis of abdominal aortic aneurysms. Marked vessel wall inflammation, which can be detected in a significant proportion of our study patients, raises the possibility of a higher incidence rate of large vessel vasculitis underlying abdominal aortic aneurysms.

Acknowledgements: NIL.

Disclosure of Interests: None declared.