Manisha R. Shah

Human atherosclerotic abdominal aortic aneurysms produce interleukin (IL)-6 and interferon-gamma but not IL-2 and IL-4: The possible role for IL-6 and interferon-gamma in vascular inflammation

Immunological mechanisms play an important role in the pathogenesis of atherosclerosis and atherosclerotic abdominal aortic aneurysms (AAA). Inflammatory leukocytes invade the vessel wall and produce cytokines which perpetuate the immune events underlying these diseases. Interleukin (IL)-1β, IL-8, tumor necrosis factor-α, and monocyte chemoattractant protein-1, among others, may play a role in the generation by AAA. The aim of this study was to investigate the possible pathogenetic role of other proinflammatory cytokines, namely IL-2, IL-4, IL-6, and interferon (IFN)-gamma. Enzyme-linked immunosorbent assay of human explant culture supernatants revealed a significant increase in IFN-gamma production by AAAcompared to occlusive (atherosclerotic) or normal (NL) aortic explants. IL-6 production was also increased in AAA compared to NL aortic explant supernatants. Neither AAA nor NL aortic tissues produced IL-2 or IL-4 in the same culture system. These results suggest that IL-6, a cytokine involved in T and B lymphocyte activation during inflammation, and IFN-gamma, which stimulates T and B lymphocytes, macrophages, endothelial cells and fibroblasts, may play a role in the pathogenesis of various vascular inflammatory diseases such as AAA.

Interleukin-8 and tumor necrosis factor-alpha are involved in human aortic endothelial cell migration: The possible role of these cytokines in human aortic aneurysmal blood vessel growth

Angiogenesis, the growth and proliferation of blood vessels, may be important in the pathogenesis of atherosclerosis and thus in human atherosclerotic abdominal aortic aneurysms (AAAs). Endothelial migration or chemotaxis is a vital component of the angiogenic response. Here, human aortic endothelial cells (hAECs) were used to investigate the effect of AAA tissue supernatants on hAEC chemotaxis. AAA tissue conditioned media were found to be chemotactic for hAECs. We have previously shown that the angiogenic cytokines interleukin (IL)-8, and tumor necrosis factor (TNF)-alpha are present in AAAs and normal aortic explant conditioned media. Currently, we have found that basic fibroblast growth factor (bFGF) and platelet-derived growth factor can also be detected in these supernatants. In order to identify whether some of these soluble mediators contributed to the chemotactic activity of these supernatants, conditioned media were preincubated with either neutralizing anti-IL-8, anti-TNF-alpha, anti-bFGF antibodies or control serum. Anti-IL-8 and anti-TNF-alpha significantly inhibited AAA tissue supernatant-induced hAEC chemotaxis (p < 0.05), while anti-bFGF did not (p not significant). These results indicate that IL-8 and TNF-alpha may be important in chemotactic activity for hAECs in vitro and possibly in AAA neovascularization. The abrogation of angiogenesis using neutralizing antibodies may be a future goal in the therapy of certain disease states such as AAA where angiogenesis plays an important role.

Intercellular adhesion molecule-1 (ICAM-1) expression and soluble ICAM-1 (sICAM-1) production by cytokine-activated human aortic endothelial cells: a possible role for ICAM-1 and sICAM-1 in atherosclerotic aortic aneurysms.

The interactions of inflammatory cells, cytokines, and cell adhesion molecules (CAM) may be important in the pathogenesis of vascular diseases such as abdominal aortic aneurysms (AAA), in which inflammation plays a role. The aim of this study was to investigate the pathogenic role of ICAM‐1, a molecule involved in leucocyte‐endothelial interactions, in vascular inflammation. ELISA of human explant culture supernatants revealed a four‐fold increase in sICAM‐1 production by AAA (n = 9) versus normal (n = 8) aortic explants. Human aortic endothelial cell (hAEC) culture was used for further studies as an in vitro model for aortic inflammatory conditions. Tumour necrosis factor‐alpha (TNF‐α) or IL‐β treatment of hAEC resulted in an up to 1‐8‐fold significant increase in sICAM‐1 production compared with resting cells. In addition, the expression of ICAM‐1 on cytokine‐stimulated versus resting hAEC was measured by radioimmunoassay. TNF‐α significantly induced ICAM‐1 expression on these cells. These results suggest that different forms of ICAM‐1, present on or released by the activated aortic endothelium, may be involved in leucocyte adhesion to and migration into the vessel wall.

Expression of Basic Fibroblast Growth Factor and Angiogenin in Arthritis

Angiogenesis is an integral component of the vasculoproliferative phase of rheumatoid arthritis (RA). We examined the distribution of two angiogenic factors, basic fibroblast growth factor (bFGF) and angiogenin (ANG) in arthritic diseases. We used an enzyme-linked immunosorbent assay and immunohistochemical analysis to determine the levels of bFGF and ANG in synovial fluid (SF) and their distribution in synovial tissue (ST), respectively. Most SF contained little or no detectable bFGF ( < 5 pg/ml). ANG in RA SF was 248.7 +/- 17.4 ng/ml, which did not differ significantly from levels found in osteoarthritis (OA; 305.9 +/- 23.1 ng/ml). Synovial lining cells, macrophages, endothelial cells, and vascular smooth muscle cells were immunopositive for bFGF and ANG; however, their expression was not up-regulated in RA ST compared to ST from OA and normal subjects. Though bFGF and ANG are present in the joints of patients with arthritic diseases, they are not up-regulated in RA. These results suggest that not all angiogenic mediators are up-regulated in RA compared to normal subjects and subjects with other arthritic diseases. It may be that some of these mediators, like ANG, play a role in the physiology of normal synovium.

Increased ICAM-1 expression in aortic disease.

PURPOSE In this investigation we evaluated the expression of vascular adhesion molecules: intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1) in normal and diseased aorta. METHODS Aortic tissue was obtained during operations for abdominal aortic aneurysms (AAA) (inflammatory, n = 3, noninflammatory, n = 6), aortic occlusive disease (AOD) (n = 6), or from fresh cadavers (NL) (n = 5). The tissue was stained with the avidin-biotin complex with the following primary antibodies: anti-ICAM-1-AA6, anti-E-selectin-BB11, and anti-VCAM-1-4B9. The slides were assigned an inflammatory score of 0 to 3, and the percentage of each cell type staining, 0% to 100%. RESULTS A trend towards a higher inflammatory score was found in the vessel wall in AAA (2.4 +/- 1.8) as compared with AOD (1 +/- 0.37) or NL (0.2 +/- 0.2). There was no statistical difference. A significant elevation in ICAM-1 expression (p < or = 0.06), however, was demonstrated in the adventitial endothelial cells of AAA (85.8% +/- 7.8%), and AOD (80.0% +/- 11.1%), as compared with NL (30.8% +/- 12.2%). Both E-selectin and VCAM-1 were expressed in all groups, but no statistical difference was demonstrated. CONCLUSIONS Patients with AAA and AOD display a significant upregulation of the expression of ICAM-1, suggesting a role for this protein in the initiation or maintenance of degenerative aortic diseases.