Bacterial and fungal microbiome analysis of stool, blood, thrombus and aneurysm wall samples from abdominal aortic aneurysm patients
Nemes-Nikodém Éva
KÁROLY RÁCZ CONSERVATIVE MEDICINE PROGRAM
Dr. Fekete Andrea
SE Szemészeti Klinika, Tanterem
2026-09-23 14:00:00
Dermatology and Venereology
Dr. Sárdy Miklós
Dr. Ostorházi Eszter
Dr. Kardon Tamás
Dr. Csire Márta
Dr. Wikonkál Norbert Miklós
Dr. Albertné Dr. Gecse Kinga
Dr. Tóth Attila
Abdominal aortic aneurysm is a life-threatening vascular condition characterized by pathological dilation and inflammatory degeneration of the vascular wall. Several studies have demonstrated that, besides established risk factors including smoking, hypertension, obesity, and cardiovascular disease, microbial factors also play a significant role in the pathogenesis and progression of AAA. Previous research has confirmed that there is a connection between the composition of the gut, but also the oral microbiome, and the development and progression of AAA. In this PhD thesis, we analysed the bacterial and fungal microbiome composition of stool, blood, thrombus and damaged vessel wall samples collected during surgery from AAA patients using bacterial 16S rRNA and fungal ITS sequencing. As a negative control for the blood vessel wall microbiome comparisons, we used human femoral arteries collected from healthy donors. The primary objective of our study was to investigate potential differences in the microbiome composition of aneurysmal versus healthy vessel walls, focusing on both bacterial and fungal communities. Secondly, to investigate whether the microorganisms detected in thrombus and aneurysm may originate from stool and be transported to these sites via the bloodstream. Thirdly, based on the compositional differences between healthy and aneurysmal microbiomes, it can be hypothesized whether microorganisms exert a direct effect or play an indirect role through their enzymatic activity in protection or pathogenicity. We demonstrated the glaring discrepancy in the bacterial and fungal microbiome composition between healthy and aneurysmal vascular walls. Upon individual analysis of the four sample types, we were unable to confirm or exclude the existence of the gut-vascular wall axis; however, it is hypothesized that the microbiome detected in the vascular wall may originate from anatomical sites other than the gut, such as the oral cavity, skin, or urinary tract. Examination of the enzymatic activities of bacteria within the microbiome revealed that iron chelate-transporting ATPase and polar amino acid-transporting ATPase exert protective effects in the healthy vascular wall. Furthermore, bacterial peptidylprolyl isomerase activity detected in aneurysmal tissue contributes to the exacerbation of aneurysm development. By examining the differences in the fungal genera present in the microbiome in aneurysmal and healthy vessel walls, we also supported the pro-inflammatory effect of Malassezia and the anti-inflammatory effect of Tomentella.
