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

OBJECTIVE: Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease. Studies of human aneurysm tissue demonstrate dense inflammatory cell infiltrates with CD4+ 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 Rag1-deficient (Rag1-/-) mice, without mature T lymphocytes, at 7 weeks of age were given 5 × 106 of human CD4+ T cells intraperitoneally. Then the mice underwent CaCl2 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+ 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 CaCl2 model of AAA. To determine the role of human T cells in AAA formation, Rag1-/- mice, resistant to CaCl2-aneurysm induction, were transplanted with human CD4+ T cells. Human CD4+ 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.

CD95-ligand contributes to abdominal aortic aneurysm progression by modulating inflammation.

AIMS: Abdominal aortic aneurysm (AAA) is one of the number of diseases associated with a prominent inflammatory cell infiltration, matrix protein degradation, and smooth muscle cell apoptosis. CD95 is an inflammatory mediator and an apoptosis inducer. Previous studies have shown elevated expression of CD95 or CD95L in the aortic tissue of AAA patients. However, how the CD95L/CD95 contributes to aneurysm degeneration and whether blocking its signalling would be beneficial to disease progression remains largely unknown. In the present study, we sought to determine the role of CD95L and its downstream target, caspase 8, in AAA progression. METHODS AND RESULTS: By using the CaCl2 murine model of AAA, abdominal aortic aneurysms were induced in C57BL/6 mice. We found that both mRNA and protein levels of CD95L were increased in aneurysm tissue compared with NaCl-treated normal aortic tissue. To determine whether CD95L contributes directly to aneurysm formation, we used CD95L null (CD95L-/-) mice to examine their response to CaCl2 aneurysm induction. Six weeks after periaortic application of CaCl2, aortic diameters of CD95L-/- mice were significantly smaller compared to CaCl2-treated wild-type controls. Connective tissue staining of aortic sections from CaCl2-treated CD95L-/- mice showed minimal damage of medial elastic lamellae which was indistinguishable from the NaCl-treated sham control. Furthermore, CD95L deficiency attenuates macrophage and T cell infiltration into the aortic tissue. To study the role of CD95L in the myelogeous cells in AAA formation, we created chimaeric mice by infusing CD95L-/- bone marrow into sub-leathally irradiated wild-type mice (WT/CD95L-/-BM). As controls, wild-type bone marrow were infused into sub-leathally irradiated CD95L-/- mice (CD95L-/-/WTBM). WT/CD95L-/-BM mice were resistant to aneurysm formation compared to their controls. Inflammatory cell infiltration was blocked by the deletion of CD95L on myeloid cells. Western blot analysis showed the levels of caspase 8 in the aortas of CaCl2-treated wild-type mice were increased compared to NaCl-treated controls. CD95L deletion inhibited caspase 8 expression. Furthermore, a caspase 8-specific inhibitor was able to partially block aneurysm development in CaCl2-treated aneurysm models. CONCLUSION: These studies demonstrated that inflammatory cell infiltration during AAA formation is dependent on CD95L from myelogeous cells. Aneurysm inhibition by deletion of CD95L is mediated in part by down-regulation of caspase 8.

Correction: Premature aortic smooth muscle cell differentiation contributes to matrix dysregulation in Marfan Syndrome.

[This corrects the article DOI: 10.1371/journal.pone.0186603.].

Model for prioritization of Graduate Medical Education funding at a university setting - Engagement of GME committee with the Clinical Enterprise.

BACKGROUND: Funding for graduate medical education (GME) is becoming scarce and is likely to worsen. There is a higher degree of accountability and return on investment demanded from public funds dedicated to GME. Academic centers (AC) partnered with clinical enterprises (CE) are finding it increasingly difficult to retain sustainable funding streams for GME activities. METHODS: To develop and implement a novel algorithmic funding model at one AC in symbiotic partnership with the CE for all 50 GME programs with nearly 500 residents. RESULTS: A new GME Finance and Workforce Committee was convened which was tasked with developing the novel algorithmic financial model to prioritize GME funding. Early outcomes measures that were monitored consisted of: satisfaction of all stakeholders and financial savings. CONCLUSIONS: The model was presented to all the stakeholders and was well received and approved. Early signs, demonstrated AC and CE satisfaction with the model, financial savings and increased efficiency. This GME funding model may serve as a template for other academic centers with tailored modifications to suit their local needs, demands and constraints.

IL-1ß (Interleukin-1ß) and TNF-α (Tumor Necrosis Factor-α) Impact Abdominal Aortic Aneurysm Formation by Differential Effects on Macrophage Polarization.

OBJECTIVE: Abdominal aortic aneurysms are inflammatory in nature and are associated with some risk factors that also lead to atherosclerotic occlusive disease, most notably smoking. The purpose of our study was to identify differential cytokine expression in patients with abdominal aortic aneurysm and those with atherosclerotic occlusive disease. Based on this analysis, we further explored and compared the mechanism of action of IL (interleukin)-1ß versus TNF-α (tumor necrosis factor-α) in abdominal aortic aneurysm formation. APPROACH AND RESULTS: IL-1ß was differentially expressed in human plasma with lower levels detected in patients with abdominal aortic aneurysm compared with matched atherosclerotic controls. We further explored its mechanism of action using a murine model and cell culture. Genetic deletion of IL-1ß and IL-1R did not inhibit aneurysm formation or decrease MMP (matrix metalloproteinase) expression. The effects of IL-1ß deletion on M1 macrophage polarization were compared with another proinflammatory cytokine, TNF-α. Bone marrow-derived macrophages from IL-1ß-/- and TNF-α-/- mice were polarized to an M1 phenotype. TNF-α deletion, but not IL-1ß deletion, inhibited M1 macrophage polarization. Infusion of M1 polarized TNF-α-/- macrophages inhibited aortic diameter growth; no inhibitory effect was seen in mice infused with M1 polarized IL-1ß-/- macrophages. CONCLUSIONS: Although IL-1ß is a proinflammatory cytokine, its effects on aneurysm formation and macrophage polarization differ from TNF-α. The differential effects of IL-1ß and TNF-α inhibition are related to M1/M2 macrophage polarization and this may account for the differences in clinical efficacy of IL-1ß and TNF-α antibody therapies in management of inflammatory diseases.

Transesophageal Echocardiogram-Guided Stent Placement in Superior Vena Cava Syndrome Secondary to Granulomatous Lung Disease: A Case Series and Literature Review.

Obstruction of the superior vena cava (SVC) is an uncommon, but potentially life-threatening condition due to likely development of edema in the head and neck and potential respiratory compromise. Less than half of those affected by SVC syndrome survive more than a year. Obstruction can be from neoplasms or secondary to benign disease. Treatment for most cases of symptomatic SVC syndrome involves placement of a stent to relieve the stenosis. Serious complications such as stent migration, pulmonary embolism, and cardiac tamponade can occur in 5% to 10% of cases, and inadequate imaging of the SVC-atrial junction by fluoroscopy contributes to these problems. The overlapping contrast in the atrium makes it difficult to precisely place the distal end of the stent, potentially allowing for embolization of the stent to occur. We present a case series of 3 patients wherein transesophageal echocardiography was used for guidance of stent placement in the SVC and significantly aided in placement.

Premature aortic smooth muscle cell differentiation contributes to matrix dysregulation in Marfan Syndrome.

Thoracic aortic aneurysm and dissection are life-threatening complications of Marfan syndrome (MFS). Studies of human and mouse aortic samples from late stage MFS demonstrate increased TGF-ß activation/signaling and diffuse matrix changes. However, the role of the aortic smooth muscle cell (SMC) phenotype in early aneurysm formation in MFS has yet to be fully elucidated. As our objective, we investigated whether an altered aortic SMC phenotype plays a role in aneurysm formation in MFS. We describe previously unrecognized concordant findings in the aortas of a murine model of MFS, mgR, during a critical and dynamic phase of early development. Using Western blot, gelatin zymography, and histological analysis, we demonstrated that at postnatal day (PD) 7, before aortic TGF-ß levels are increased, there is elastic fiber fragmentation/disorganization and increased levels of MMP-2 and MMP-9. Compared to wild type (WT) littermates, aortic SMCs in mgR mice express higher levels of contractile proteins suggesting a switch to a more mature contractile phenotype. In addition, tropoelastin levels are decreased in mgR mice, a finding consistent with a premature switch to a contractile phenotype. Proliferation assays indicate a decrease in the proliferation rate of mgR cultured SMCs compared to WT SMCs. KLF4, a regulator of smooth muscle cell phenotype, was decreased in aortic tissue of mgR mice. Finally, overexpression of KLF4 partially reversed this phenotypic change in the Marfan SMCs. This study indicates that an early phenotypic switch appears to be associated with initiation of important metabolic changes in SMCs that contribute to subsequent pathology in MFS.

Current status of international experiences in general surgery residency programs in the United States.

BACKGROUND: The aim of this study is to identify, quantify, and characterize the international experiences available for general surgery residents in the general surgery residency programs in the United States (US). METHODS: The Fellowship and Residency Electronic Interactive Database (FREIDA) database was used to identify all the general surgery residency programs in the US. Each institution was contacted by both e-mail and telephone. Respondents were asked if an international experience was available for residents within their program and, if available, details of the experience were obtained. RESULTS: A total of 253 general surgery residency programs were identified using the FREIDA database. Eighty-six (34 %) programs were noted to offer an international experience for their residents. A majority are incorporated into the PGY 3 and PGY 4 level of training with a duration of 1-4 weeks. Common locations are evenly distributed among the Americas and Africa and are usually funded through a combination of resident and department funding. CONCLUSIONS: US resident interest in global health is growing along with an increasing demand for surgical care worldwide. This is one of the first studies to identify, quantify, and characterize in detail the international experiences currently available to general surgery residents within the general surgery training programs in the US. These results can help general surgery residency applicants with an interest in global health and also pave the path for residency programs to develop future international experiences.

Elastin-Derived Peptides Promote Abdominal Aortic Aneurysm Formation by Modulating M1/M2 Macrophage Polarization.

Abdominal aortic aneurysm is a dynamic vascular disease characterized by inflammatory cell invasion and extracellular matrix degradation. Damage to elastin in the extracellular matrix results in release of elastin-derived peptides (EDPs), which are chemotactic for inflammatory cells such as monocytes. Their effect on macrophage polarization is less well known. Proinflammatory M1 macrophages initially are recruited to sites of injury, but, if their effects are prolonged, they can lead to chronic inflammation that prevents normal tissue repair. Conversely, anti-inflammatory M2 macrophages reduce inflammation and aid in wound healing. Thus, a proper M1/M2 ratio is vital for tissue homeostasis. Abdominal aortic aneurysm tissue reveals a high M1/M2 ratio in which proinflammatory cells and their associated markers dominate. In the current study, in vitro treatment of bone marrow-derived macrophages with EDPs induced M1 macrophage polarization. By using C57BL/6 mice, Ab-mediated neutralization of EDPs reduced aortic dilation, matrix metalloproteinase activity, and proinflammatory cytokine expression at early and late time points after aneurysm induction. Furthermore, direct manipulation of the M1/M2 balance altered aortic dilation. Injection of M2-polarized macrophages reduced aortic dilation after aneurysm induction. EDPs promoted a proinflammatory environment in aortic tissue by inducing M1 polarization, and neutralization of EDPs attenuated aortic dilation. The M1/M2 imbalance is vital to aneurysm formation.

Recurrent Admissions for Respiratory Distress Caused by Large Renal AVF.

Renal arteriovenous fistulas (AVFs) are an uncommon complication of nephrectomy. In this report, we present the case of a 66-year-old female presenting with progressive dyspnea on exertion and exercise intolerance. She was diagnosed and treated for adult onset reactive airway disease. The patient underwent nephrectomy at age 18 secondary to recurrent pyelonephritis from vesicoureteral reflux. She underwent a surveillance computed tomography (CT) scan to evaluate a small ascending aneurysm that was initially detected on cardiac echocardiogram. A large left renal AVF was detected incidentally on the CT scan. The fistula was successfully treated by ligation of the renal artery with resolution of pulmonary symptoms.

Background differences in baseline and stimulated MMP levels influence abdominal aortic aneurysm susceptibility.

OBJECTIVE: Evidence has demonstrated profound influence of genetic background on cardiovascular phenotypes. Murine models in Marfan syndrome (MFS) have shown that genetic background-related variations affect thoracic aortic aneurysm formation, rupture, and lifespan of mice. MFS mice with C57Bl/6 genetic background are less susceptible to aneurysm formation compared to the 129/SvEv genetic background. In this study, we hypothesize that susceptibility to abdominal aortic aneurysm (AAA) will be increased in 129/SvEv mice versus C57Bl/6 mice. We tested this hypothesis by assessing differences in aneurysm size, tissue properties, immune response, and MMP expression. METHODS: Mice of C57Bl/6 or 129/SvEv background underwent AAA induction by periaortic application of CaCl2. Baseline aortic diameters, tissue properties and MMP levels were measured. After aneurysm induction, diameters, MMP expression, and immune response (macrophage infiltration and bone marrow transplantation) were measured. RESULTS: Aneurysms were larger in 129/SvEv mice than C57Bl/6 mice (83.0% ± 13.6 increase compared to 57.8% ± 6.4). The aorta was stiffer in the 129/SvEv mice compared to C57Bl/6 mice (952.5 kPa ± 93.6 versus 621.4 kPa ± 84.2). Baseline MMP-2 and post-aneurysm MMP-2 and -9 levels were higher in 129/SvEv aortas compared to C57Bl/6 aortas. Elastic lamella disruption/fragmentation and macrophage infiltration were increased in 129/SvEv mice. Myelogenous cell reversal by bone marrow transplantation did not affect aneurysm size. CONCLUSIONS: These data demonstrate that 129/SvEv mice are more susceptible to AAA compared to C57Bl/6 mice. Intrinsic properties of the aorta between the two strains of mice, including baseline expression of MMP-2, influence susceptibility to AAA.