Endothelial and myointimal cell functions related to vascular inflammation and remodeling in Giant-Cell Arteritis: Contribution of interleukin-23p19, interleukin-35 and endothelin-1
[eng] Giant cell arteritis (GCA) is vascular inflammatory disease frequently involving large and medium sized arteries. GCA pathogenesis is not completely characterized, although there is a well accepted general model based on the observation of the histopathology and supported by immunopathology st...
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| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Recursos: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/109224 |
| Acesso em linha: | https://hdl.handle.net/2445/109224 http://hdl.handle.net/10803/401863 |
| Access Level: | acceso abierto |
| Palavra-chave: | Arteritis de cèl·lules gegants Vasculitis Malalties autoimmunitàries Citoquines Giant cell arteritis Rheumatology Autoimmune diseases Cytokines |
| Resumo: | [eng] Giant cell arteritis (GCA) is vascular inflammatory disease frequently involving large and medium sized arteries. GCA pathogenesis is not completely characterized, although there is a well accepted general model based on the observation of the histopathology and supported by immunopathology studies. According to this model, CD4+T cells subsets (mainly Th1 and Th17) and macrophages are essential to orchestrate the amplification of pro-inflammatory cascades leading to chronic inflammation of the vessel wall. The main sites of entry of infiltrating leukocytes are the activated endothelial cells (EC) from the adventitial vasa vasorum. Importantly, the secretion of proteases by macrophages among others, promotes elastic lamina degradation and migration of leukocytes to the inner artery layers. Vascular smooth muscle cells (VSMC) have also an important role in GCA pathogenesis since, in this scenario; they acquire a pro-inflammatory phenotype by overexpressing adhesion molecules and pro-inflammatory cytokines, contributing to the persistence of inflammation. Inflammatory cell products, as well as vascular injury, trigger a vascular remodelling process which leads to the development of intimal hyperplasia and vascular lumen occlusion. VSMC acquisition of proliferative and migratory phenotype may contribute to vascular remodeling. Further investigation of molecules involved in GCA pathogenesis is needed in order to find new strategies to improve the current GCA treatment (glucocorticoids) since 50% of the patients relapse and 40% suffer form early (visual loss or stroke) or late (aortic aneurysm) complications derived from maladaptive vascular remodeling. For this reason, the aim of this doctoral thesis was to contribute knowledge to these GCA challenges by investigating new roles of two important molecules involved in the persistence of inflammation (IL-23p19 and IL-35) as well as a new role of endothelin 1 (ET-1) in GCA vascular remodeling. The IL-12 superfamily of cytokines is composed by four heterodimeric cytokines: IL-12 (p40 + p19), IL-23 (p40 ad p19), IL-27 (p28 and Ebi3) and IL-35 (Ebi3 and p35). Regarding to these cytokines, we have demonstrated a dichotomy in the expression of p19 and p40 subunits suggesting a role for p19 independent from p40 heterodimerization. We observed that p19 but not p40 was induced by a pro- inflammatory context in EC from the adventitial vasa vasorum of GCA specimens. Moreover, p19 was not secreted by stable p19-expressing EC suggesting an intracellular role. Our studies showed that p19 contributed to leukocyte attachment and transmigration by promoting overexpression of adhesion molecules ICAM-1 and VCAM-1. We also demonstrated that these effects were triggered by intracellular p19 binding to gp130 receptor, subsequently promoting phoshporylation and nuclear translocation of STAT3. IL-35 cytokine was also investigated as a consequence of the previous observation that p35 (but not p40) was constitutively expressed by VSMC of GCA specimens. This dichotomy suggested that p35 may have and independent role from that derived from p40 heterodimerization or that p35 may have another partner to form a cytokine different from IL-12. Our results demonstrated that p35 dimerizes with Ebi3 subunit in order to form IL-35 in GCA specimens. Interestingly, we found that IL-35 was mainly produced by leukocytes and VSMC in the adventitial/media junctions of GCA lesions. In order to mimic this context, we used co-cultures of temporal artery-derived primary VSMC together with leukocytes which demonstrated that IL-35 expression in VSMC was increased by pro-inflammatory cytokines IL-1β, TNFα and IFNg. In addition, we have demonstrated a new role for this cytokine in VSMC. IL-35 interacts with gp130 in order to promote pro-inflammatory phenotype of VSMC. This is an important observation since, until present; IL-35 has been described as an anti-inflammatory cytokine involved in regulatory T cell (Treg) differentiation. We previously reported that endothelin-1 (ET-1) and its receptors ETAR and ETBR are over-expressed in GCA lesions and GCA patients with ischemic complications have increased serum concentrations of ET-1. Although it has been observed that ET-1 may contribute to myofibroblast differentiation of fibroblasts, a crucial step in lung and skin fibrogenic diseases, the most investigated function of ET-1 in VSMC has been vascular tone regulation. In this thesis, we have demonstrated that ET-1 may contribute to vascular occlusion, by promoting the migration of VSMC through activation of the focal adhesion kinase (FAK)/Src and PI3K axis. In GCA lesions ET-1 was mainly produced by inflammatory cells and the interaction with PBMC increased ET-1 receptor expression by VSMC. ET-1 stimulated VSMC migration by inducing focal adhesion kinase (FAK) phosphorylation at Y397 permitting association with p85 subunit of PI3Kinase which co-localized with FAK at the cell protrusions of migrating cells. Accordingly, inhibition of both FAK and PI3K abrogated ET-1 induced migration. Consistently, blockade of ETAR and ETBR with BQ123 and BQ788 antagonists inhibited ET-1 induced VSMC migration and VSMC outgrowth from cultured GCA-arteries. |
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