Objective We have previously demonstrated that human abdominal aortic aneurysm (AAA) rupture occurs in zones of low wall shear stress where flow recirculation and intraluminal thrombus (ILT) deposition are increased. Matrix metalloproteinase-9 (MMP-9) is involved in the pathogenesis of AAA via its lytic effect on collagen and elastin. We hypothesize that flow-mediated ILT deposition promotes increased local inflammatory and MMP-9 activity that leads to AAA wall degeneration. The purpose of this study was to examine the correlation between predicted pulsatile flow dynamics and regional differences in MMP-9, elastin, collagen, and ILT deposition in human AAA. Methods Full-thickness aortic tissue samples were collected from 24 patients undergoing open AAA repair. Control infrarenal aortic tissue was obtained from 6 patients undergoing aortobifemoral bypass. Full-thickness aortic tissue and ILT were assessed for MMP-9 levels using a cytokine array assay. Histologic and immunohistochemical assessment of inflammation, collagen and elastin content, and MMP-9 levels were also measured. Three-dimensional AAA geometry was generated from computed tomography angiogram (CTA) images using Mimics software and computational fluid dynamics was used to predict pulsatile aortic blood flow. Results The majority of AAA showed eccentric ILT deposition which was correlated with predicted recirculation blood flow (R 2 = –0.17; P < .05). The regions of high ILT were associated with significant increases in inflammation and loss of elastin and collagen compared with regions of low ILT, or with control tissue. MMP-9 was significantly higher in areas of high ILT deposition compared with areas devoid of ILT. Tissue MMP-9 was correlated with the thickness of ILT deposition (R 2 = 0.46; P < .05), and was also present in high levels in thick compared with thin ILT. Conclusions We have shown a correlation between flow-mediated ILT deposition with increased tissue levels of MMP-9 activity, increased inflammatory infiltrate, and decreased elastin and collagen content in stereotactically sampled human AAA, suggesting that ILT deposition is associated with local increases in proteolytic activity that may preferentially weaken and promote rupture at selected regions.
Fisher exact test, analysis of variance, or Wilcoxon ranksum tests, as appropriate. Logistic regression was used to compare the effect of single Proglide use on VARC-2 and BARC. Results: A total of 131 cases were included, of which 116 had bilateral single Proglide for access closure. Patient demographic and operative data are presented in Tables I and II, respectively. Groups were similar for all characteristics except smoking status, with an increased proportion of former smokers in the nonsingle Proglide group. There were 119 patients (90.8%) who had single Proglide use on the right femoral artery and 121 (92.4%) on the left. Sixteen patients had Proglide deployment issues (12.2%). VARC2 occurred in 8 of 131 patients (6.11%)d6 of 116 (5.17%) with bilateral single Proglides and 2 of 15 (13.3%) with at least two Proglides on one access site. BARC occurred in 6 of 131 patients (4.58%)d5 of 116 (4.31%) with bilateral single Proglides and 1 of 15 (6.67%) with at least two Proglides on one access site. Single Proglide use was not associated with a difference in VARC-2 (odds ratio, 0.35; 95% confidence interval, 0.64-1.94) or BARC (odds ratio, 0.63; 95% confidence interval, 0.07-6.79). No patients developed pseudoaneurysms or required repeat intervention for bleeding. The median length of stay was 1 day. Conclusions: Single Proglide use per vascular access site in patients undergoing EVAR is a safe and effective method for access closure.
Intergraft variability in nonhematopoietic immunoregulatory cell number and expression of immune checkpoint inhibitor receptors and ligands in both allo- and autografts: potential target for intervention Qingdong Guan,1-3 Scott Gilpin,3 James Doerksen,3 Lauren Bath,3 Tracey Lam,3 Kristjan Paulson,4 Pascal Lambert,4 Yun Li,1,3 Donna A.Wall1-4 1, Department of Pediatrics and Child Health, 2, Immunology, University of Manitoba; 3, Manitoba Center for Advanced Cell and Tissue Therapy; 4, CancerCare Manitoba The number of CD34+ hematopoietic stem/progenitor cells (HSC) in HSC products is the main and often sole characterization of the graft used in HSCT. However CD34+ cells make up only 0.3-5% of the graft with the rest of the cells being lymphocytes and immature myeloid and granulocytic cells, including myeloid-derived suppressor cells (MDSC). We examined a cohort of HSC products collected from 2010-2014. Filgrastim and chemotherapy was used to mobilize 60 multiple myeloma and 34 lymphoma patients. Filgrastim-mobilized healthy donor products used in allografts (N=68) was a comparator. Aliquots stored in liquid nitrogen were analyzed for cell phenotype with a focus on immunoregulatory populations. We found CD33+CD15-CD14+HLA-DR-/low monocytic (M-MDSC) ranged from 0-59% in the infused graft. Similarly CD3+T lymphocyte ranged from 2-80% in the graft. There were 10-50 fold more M-MDSC than CD34+ cells with the infused M-MDSC cell dose ranging from 0-600×106/kg (Fig 1). Similarly CD3+T cell dose ranged from 4-670×106/kg (Fig1). M-MDSC were functional as they could suppress T cell proliferation and IFN-γ secretion, but promote regulatory T cell development in vitro. We examined receptor-ligand relations between M-MDSC and T cells and markers of T exhaustion. M-MDSC expressed variable PD-L1 (19.3±13.9% for MM, 10.4±4.4% for lymphoma and 7.0±4.8% for allografts), and CD86 (48.3±17.1% for MM, 59.9±15.4% for lymphoma and 57.8±17.0% for allografts), the ligands for PD-1 and CTLA-4, respectively. Blocking PD-L1-PD-1 signaling pathway using anti-PD-L1 or anti-PD1 partially reversed the suppressive functions of M-MDSC. Compared to allografts, CD4+T and CD8+T cells in the autografts showed poor proliferation, decreased the secretion of IFN-γ and/or granzyme B, and increased inhibitory receptors PD-1 and CTLA-4 on their surface - markers of T cell exhaustion. Levels of PD-L1 and CD86 on M-MDSC were correlated with expression of inhibitory receptors PD-1 and CTLA-4 on T cells, respectively. Taken together, our pilot data showed variable numbers of M-MDSC are infused with HSC grafts. These cells have strong immune regulatory function in vitro. T cells in autografts have high levels of T cell exhaustion markers and are less functional. It indicated immune function may be enhanced by interfering with PD1/PDL1 or CTLA-4. The numbers of M-MDSC and T cells are in the range of a cellular therapy product and may be targeted for enhance/inactivation pre- or peri-transplant immune function. Figure 1. The infusion cell dose of CD34+ stem cells, M-MDSC and CD3+T. Disclosures No relevant conflicts of interest to declare.
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