Leukocyte subsets and abdominal aortic aneurysms detected by screening in men

Abstract

Objective In the present case–control study, we describe the associations between leukocyte subsets in blood and early, screening‐detected AAA in men. An abdominal aortic aneurysm (AAA) may result in a life‐threatening rupture of the aortic wall. The trigger for AAA formation remains unknown, but the vascular adventitia of advanced AAAs is infiltrated by various leukocytes, indicating that the pathogenesis may involve inflammation. Methods In Sweden, all 65‐year‐old men are invited to an ultrasound examination for detection of AAA. At the Gothenburg screening site, 16 256 men were examined in 2013–2017, 1.2% of whom had an AAA (diameter of the infrarenal aorta ≥30 mm). All men with AAA at screening as well as a randomized selection of AAA‐free screened men were invited to participate in a case–control study. Results The median diameter of AAAs was 33 mm. Men with an AAA (n = 151) had a higher frequency of smoking, hypertension and statin use than controls (n = 224). Blood levels of neutrophils, lymphocytes, monocytes and basophils were higher in individuals with an AAA, but eosinophil count did not differ from controls. Odds ratios (95% confidence interval) for AAA were 8.6 (4.2–17.4), 3.5 (1.9–6.6) and 3.3 (1.8–6.3) for the highest versus lowest quartile of neutrophils, lymphocytes and monocytes, respectively. For neutrophils and lymphocytes, the association with AAA remained significant after adjustment for smoking and other known risk factors/markers. Conclusion Several, but not all, subsets of circulating leukocytes are associated with screening‐detected AAA in men, which is insufficiently explained by associations with smoking and other confounders.

Low Progesterone and Low Estradiol Levels Associate With Abdominal Aortic Aneurysms in Men

“…Importantly, AAA men are more affected by atherosclerosis-based cardiovascular disease ( 34 ) and there is ample evidence that low levels of other sex hormones, such as testosterone and DHEA, associate with cardiovascular diseases in men ( 35 , 36 ). Further, any systemic disease or treatments such as corticosteroids may affect the risk of AAA as well as the production of sex hormones and adrenal precursors ( 37 ), which may be a particularly important feature of diseases with an inflammatory component such as AAA ( 38 ). Although we adjusted for prevalent diseases, there may be residual confounding in our analyses, and the underlying biology of the associations found here will require further investigation.…”

Neutrophil Elastase-Derived Fibrin Degradation Products Indicate Presence of Abdominal Aortic Aneurysms and Correlate with Intraluminal Thrombus Volume

“…The AAA adventitia and outer media are highly infiltrated by T-and B-lymphocytes, plasma cells, monocytes/macrophages, natural killer cells, and mast cells (98,116,149,150) which form activated lymphoid tissue within the aneurysm wall. Several of these leukocyte subsets are also concurrently increased in peripheral blood (151). Several indications of autoimmunity in the common, degenerative, AAA have been published.…”

Neutrophils as Regulators and Biomarkers of Cardiovascular Inflammation in the Context of Abdominal Aortic Aneurysms

“…A study showed that after neutrophil depletion in mice, experimental AAA development is significantly inhibited with a decrease of both, tissue neutrophils and macrophages compared to the control group [ 76 ]. A Swedish case-control study reported on significantly higher blood counts of neutrophils, lymphocytes, monocytes, and basophils in AAA patients compared to healthy controls [ 77 ]. Neutrophils are recruited early, before monocytes, into the tissue then promoting monocyte extravasation by cytokine release, NET formation and granule protein secretion [ 78 , 79 ].…”