Abstract 1682: Mechanisms of Vascular Inflammation in a Bioengineered Human Artery Model
Background: Vascular inflammation plays a central role in vasculitis and atherosclerosis with the contribution of monocytes/macrophages, lymphocytes and vascular resident cells, including vascular smooth muscle cells (VSMC). We have demonstrated that dendritic cells (DC) are an indigenous arterial wall population and may regulate inflammatory responses. To examine mechanisms in vascular inflammation, we developed a novel model of 3-dimensional (3D) bioengineered human vessels that allowed for examining the contributions of different cellular players and mediators.
Methods: 3D vessels were constructed with human aortic VSMC and collagen type I matrix. Various numbers of monocyte and myeloid DC (from 1.5x103 to 1x105) were seeded to the outer media of 3D vessels. Constructs were co-cultured with 1x106 autologous CD4 T cells in the presence or absence of toll-like receptor stimulation by lipopolysaccharide (LPS). Cell attachment, invasion and activation were assessed by immunohistochemistry, computer-assisted microscopy and real-time PCR.
Results: DC attached proportionately to the number added (max: 115 cells/slice, p<0.0001). Monocytes, however, failed to attach to 3D constructs even after LPS activation (max: 2 cells/slice). Also, DC-free tubular constructs attracted few T cells. In DC-reconstituted vessels, LPS stimulation significantly increased the number of attaching (mean: 33.6 vs. 58.8 cells/slice, p<0.05) and invading T cells (1.6 vs. 5.3 cells/slice, p<0.001). In T cell–DC-reconstituted constructs, LPS stimulation upregulated DC-activation markers CD83 and CD86, the T cell-attracting chemokine CCL19, and its receptor CCR7 (p<0.05). Vascular DC stimulation was sufficient to induce autologous T-cell activation in the absence of antigen and CD40 ligand, interferon-γ, and interleukin-2 upregulation (p<0.05). Moreover, reconstituted constructs now succeeded to attract monocytes (mean: 12 cells/slice).
Conclusions: Bioengineered artery model studies document that DC activation is necessary to recruit T cells and monocytes into VSMC layers. Interestingly, LPS-triggered embedded DC are sufficient to break T-cell tolerance, suggesting that microbial infections can increase the risk for vascular inflammation.