Ex vivo expansion of regulatory T cells from abdominal aortic aneurysm patients inhibits aneurysm in humanized murine model

Abstract

Objective: Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease. Studies of human aneurysm tissue demonstrate dense inflammatory cell infiltrates with CD4 þ T cells predominating. Regulatory T cells (Tregs) play an important role in inhibiting pro-inflammatory T cell proliferation, therefore, limiting collateral tissue destruction. The aim of this study was to investigate whether ex vivo augmentation of human Tregs attenuates aneurysm formation in humanized murine model of AAA. Methods: Circulating Treg population in AAA patients and age-and gender-matched controls were determined by real-time polymerase chain reaction and flow cytometry. To create humanized murine model of AAA, irradiated Rag1deficient (Rag1 -/-) mice, without mature T lymphocytes, at 7 weeks of age were given 5 Â 10 6 of human CD4 þ T cells intraperitoneally. Then the mice underwent CaCl 2 aneurysm induction. Aortic diameters were measured before and at 6 weeks after aneurysm induction. Aortic tissue was collected for histology and protein extraction. Verhoeff-Van Gieson stain was used for staining elastic fiber. CD4 þ T cells in the aortic tissue were detected by immunohistochemical staining.Results: In human peripheral blood mononuclear cells, the proportion of Tregs are decreased in AAA patients compared with matched control patients with significant vascular disease. We first validated the role of Tregs in the CaCl 2 model of AAA. To determine the role of human T cells in AAA formation, Rag1 -/mice, resistant to CaCl 2 -aneurysm induction, were transplanted with human CD4 þ T cells. Human CD4 þ T cells were able to drive aneurysm formation in Rag1 -/mice. We show that ex vivo augmentation of human Tregs by interleukin-2 resulted in decreased aneurysm progression.Conclusions: These data suggest that the ex vivo expansion of human Tregs may be a potential therapeutic strategy for inhibiting progression of AAA.

Abdominal Aortic Aneurysm: Roles of Inflammatory Cells

“…Another study showed that the proportion of Treg cells in peripheral mononuclear cells were markedly decreased in AAA patients than controls (88). The average aortic diameters of Foxp3 -/mice were larger than WTs after CaCl 2 induction, while infusion of normal Treg cells to Foxp3 -/mice can render their similar aortic size with WTs after CaCl 2 induction (88). Administration of IL-2 to expanse FOXP3 + Treg cells also reduced the incidence and mortality of AAA in Apoe -/mice with angiotensin II infusion (89).…”

“…Studies have shown that EX-527, an inhibitor of SIRT1, can recover the acetylation levels of FOXP3, increase the number of active Treg cells and bring (87). Another study showed that the proportion of Treg cells in peripheral mononuclear cells were markedly decreased in AAA patients than controls (88). The average aortic diameters of Foxp3 -/mice were larger than WTs after CaCl 2 induction, while infusion of normal Treg cells to Foxp3 -/mice can render their similar aortic size with WTs after CaCl 2 induction (88).…”

Mouse models for abdominal aortic aneurysm

“…An array of different inflammation modifying regimens have recently been reported to inhibit or promote the incidence and/or rupture of AAAs formed in the different mouse models (Figure 2 and Table S1) (Amin et al, 2019;Hiromi et al, 2020;Krishna et al, 2019;Li, Nie, et al, 2019;Li, Xia, et al, 2019;Liu, Fitzgerald, et al, 2019;Liu, Kong, et al, 2019;Nie et al, 2019;Paige et al, 2019;Peshkova et al, 2019;Ren et al, 2020;Sharma, Dev, Belenchia, et al, 2019;Suehiro et al, 2019;Suh et al, 2020). The nucleotide-binding domain leucine-rich repeat (NLR) and pyrin domain-containing receptor 3 (NLRP3)-inflammasome plays an important role in innate immunity through controlling the secretion of pro-inflammatory cytokines.…”

“…A large body of published research suggests that Foxp3 + regulatory T cells inhibit AAA development within both the angiotensin II and CaCl 2 models (Golledge, 2019;Liu, Kong, et al, 2019;Suh et al, 2020;Yodoi et al, 2015). Of potential clinical application, it was recently reported that ex vivo expansion and administration of Foxp3 + regulatory enriched T cells reduced the size of CaCl 2 -induced AAAs (Suh et al, 2020). One mechanism underlying the beneficial effects of regulatory cells is through inhibiting PG production by decreasing COX-2 expression (Suh et al, 2020).…”

Pathophysiology of Aortic Aneurysms: Insights from Animal Studies

“…Treatment with IL-33 increased Tregs within the aorta and suppressed vascular smooth muscle cell (VSMC) chemokine expression. Suh et al also explored the role of Tregs in aneurysm development by using a humanized murine model of AAA by irradiating Rag1 −/− mice at 7 weeks of age and supplementing them with human CD4 + T-cells [ 50 ]. Rag1 −/− mice are resistant to aneurysm formation in the CaCl 2 model; however, when supplemented with human CD4 + cells, they became susceptible to AAA formation.…”