The pro-inflammatory and chemotactic cytokine microenvironment of the abdominal aortic aneurysm wall: a protein array study

OBJECTIVE: Cytokines are inflammatory mediators implicated in abdominal aortic aneurysm (AAA) pathogenesis. The cytokine expression profile of the AAA is poorly defined and has focused on the expression of pro-inflammatory cytokines, at the expense of chemokines and growth factors. This study aims to investigate the cytokine expression profile of the established AAA wall. METHODS: Cytokine protein expression was measured in homogenized human aortic tissue (10 AAAs and 9 nonaneurysmal controls) using a 42-cytokine antibody-based protein array. Data were quantified using densitometric analysis and statistically analyzed using a Mann-Whitney U test. RESULTS: A significant difference in cytokine expression between AAA and control samples was found in 15 of 42 cytokines. Several pro-inflammatory cytokines were upregulated within the AAA compared with the control: interleukin (IL)-6 (P = .001), IL-1alpha (P = .001), IL-1beta (P < .001), tumor necrosis factor (TNF)-alpha (P = .002), TNF-beta (P = .002), and oncostatin M (P = .007). The anti-inflammatory cytokine IL-10 was also upregulated (P = .002). Members of the chemokine family were also highly expressed within AAA samples: IL-8 (P = .001), epithelial neutrophil-activating peptide-78 (ENA-78; P = .006), growth related oncogene (GRO; P < .001), monocyte chemoattractant protein (MCP)-1 (P = .003), MCP-2 (P < .001), and regulated upon activation, normal T-cell expressed and secreted (RANTES; P = .001). Of the growth factors examined, granulocyte colony-stimulating factor (GCSF; P = .003) and macrophage colony-stimulating factor (MCSF; P = .004) were significantly higher in the AAA. CONCLUSIONS: The established AAA is characterized by a distinct cytokine profile consisting of pro-inflammatory cytokines, chemokines, and specific growth factors. This suggests that these cytokines may contribute to pathologic changes within the established, preruptured aneurysm.     

Cytokines and chemokine gene expression in human kidney transplantation

Despite advances in immunosuppression in past decades, allograft rejection remains the main reason for kidney graft failure. Recently, despite great improvements in understanding of molecular basis of allograft rejections, renal histology remains the primary method to monitor the onset of graft rejection. The aim of the present study was to ascertain whether cytokine and chemokine expression profiles in kidney allografts contributed to the diagnosis of graft dysfunction. We analyzed mRNA expression in 174 kidney graft biopsies for the following cytokines: TGF-beta1, TNF-alpha, IL-10, and chemokine RANTES. Based on the expression levels obtained by real-time RT-PCR, we correlated data with the results of morphologic examinations. All tested cytokines and chemokines were upregulated (P < .001) during acute rejection compared to nonrejecting controls. Upregulation was also found in chronic allograft nephropathy (CAN) group for TGF-beta1, IL-10 (P < .001), TNF-alpha, and RANTES (P < .01). Upregulated expression of IL-10 (P < .001), TGF-beta1, (P < .01) and RANTES (P < .05) showed borderline changes. Higher expression levels (P < .001) of TGF-beta1 and IL-10 were also found during ATN. IL-10 was upregulated (P < .01) in specimens with recurrent glomerulonephritis. Weakly increased (P < .05) expressions of TGF-beta1 were found during CsA toxicity. Distinctive expression levels between acute rejection and CAN were only found for IL-10 (P < .01). TNF-alpha showed a different expression profile in acute rejection versus ATN (P < .001). These findings suggest that distinct cytokine and chemokine expression profiles in grafts may contribute to the diagnosis for and elucidation of the immunopathologic process during graft dysfunction.     

Intestinal graft versus native liver cytokine expression in a rat model of intestinal transplantation with and without donor-specific cell augmentation

BACKGROUND: Immunomodulatory strategies such as donor-specific bone marrow or blood transfusions have been used to promote engraftment after intestinal transplants. We previously showed that delivery of donor antigen via the portal vein can effectively reduce the rate of intestinal graft rejection. The purpose of our current study was to investigate the impact of donor-specific cell augmentation (blood versus bone marrow) via the portal vein on cytokine expression in intestinal grafts versus native livers. MATERIAL AND METHODS: We performed heterotopic small intestinal transplants between male Brown-Norway (donor) and female Lewis (recipient) rats. We studied 10 groups according to the type of donor-specific cell augmentation and the use and dose of immunosuppressive therapy. For cell augmentation, donor-specific blood or bone marrow was transfused via the donor portal vein immediately before graft implantation. For immunosuppression, tacrolimus was used post-transplant at a high or low dose. Control rats received neither immunosuppression nor cell augmentation. Tissue samples for histological assessment were obtained at designated time points. RNA was extracted from intestinal graft and native liver biopsies for cytokine measurements (IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IFN-gamma, TNF-alpha, and TNF-beta). Chimerism levels were determined using Q-PCR analysis. RESULTS: Without concurrent immunosuppression, neither portal donor-specific blood nor bone marrow transfusion reduced the rate of rejection. With immunosuppression, outcome was significantly better after portal donor-specific blood (versus bone marrow) transfusion. Irrespective of the type of donor-specific cell augmentation, severe rejection caused strong cytokine expression in the grafts of IL-1 alpha, IL-1 beta, IFN-gamma, and TNF-alpha; in the native livers, mainly of TNF-alpha (with IFN-gamma showing hardly any increase). In general, rejection caused stronger cytokine expression in the grafts than in the native livers. Mild rejection correlated well with strong intragraft expression of IL-6, TNF-alpha, and TNF-beta (early rejection markers); severe rejection with IL-1 alpha, IL-1 beta, IFN-gamma, and TNF-alpha (late rejection markers).In addition to cell augmentation per se, the type of cell augmentation also had an impact on cytokine expression in both grafts and native livers. Cell-augmented (versus tacrolimus-treated) rats showed hardly any differences in intragraft cytokine expression, but the expression of almost all cytokines was significantly stronger in the native livers. With immunosuppression, bone marrow infusion increased intragraft cytokine expression of IL-1 alpha, IL-1 beta, IFN-gamma, and TNF alpha, as well as liver cytokine expression of IL-1 beta, compared to blood transfusion. This finding reflected the more advanced rejection stages in the bone marrow infused group; different types of donor-specific cell augmentation had similar effects on liver cytokine expression. In the absence of myoablative therapy, chimerism levels were low, in both cell-augmented and non-cell-augmented groups. CONCLUSIONS: Rejection and donor-specific cell augmentation independently causes differences in intragraft versus native liver cytokine expression after intestinal transplants. Portal donor-specific blood transfusion, as compared with donor-specific bone marrow infusion, lowered the incidence of rejection and diminished intragraft cytokine up-regulation.     

Prophylactic gamma radiation of unaffected vein grafts failed to prevent vein graft disease in a chronic hypercholesterolemic porcine model.

OBJECTIVE: The value of prophylactic brachytherapy on vein graft disease is unknown. METHODS AND RESULTS: Vein bypass grafts in 23 hypercholesterolemic pigs after ex vivo gamma irradiation of the vein grafts (10, 20, and 40Gy) and 16 control veins were analyzed regarding: (1) expression of platelet-derived growth factor (PDGF-AA and -BB, ELISA); (2) smooth muscle cell (SMC) proliferation/cell death (double-immunohistochemistry Mib-1/TUNEL/SMC alpha-actin); and (3) vessel wall dimensions. Planimetric data on vessel wall dimensions revealed no positive effect of gamma radiation on neointima formation and inner lumen diameter. On the contrary, vein grafts subjected to 40Gy were significantly more likely to be occluded and to have reduced inner lumen and increased neointima formation. Radiation therapy had no effect on PDGF expression and SMC proliferation/cell death. The mean inner lumen diameter decreased as PDGF-AA expression increased. CONCLUSIONS: Prophylactic gamma radiation of unaffected vein grafts failed to prevent vein graft disease in a hypercholesterolemic porcine model. High-dose radiation (40Gy) resulted in more frequent graft occlusion and vein sclerosis.     

Immunolocalization and temporal distribution of cytokine expression during the development of vein graft intimal hyperplasia in an experimental model

Purpose: Vein graft stenosis caused by intimal hyperplasia (IH) accounts for 30% to 50% of late bypass graft failures; however, the biochemical mediators of vein graft IH have been poorly defined. We attempted to evaluate the spatial and temporal distribution of five principal cytokines (interleukin-1 beta [IL-1β], platelet-derived growth factor AA [PDGF-AA], basic fibroblast growth factor [bFGF], interferon gamma [INFγ], and tumor necrosis factor alpha [TNF-α]) during the development of IH in a rat vein graft model.Methods: Rat epigastric vein interposition grafts in the femoral artery were harvested at 6 hours, 2 days, 1 week, 2 weeks, and 4 weeks after the grafting procedure and studied with immunohistochemical and standard histologic techniques. The cytokine expression in the endothelium and media/neointima was quantified as the percentage of immunopositive cells per high-power field.Results: Maximal hyperplasia occurred 2 weeks after the grafting procedure. Peak expression of IL-1β and bFGF occurred by 2 days. PDGF-AA expression paralleled the development of IH, peaking at 2 weeks and then declining. TNF-α expression increased at 1 week and remained elevated. INFγ was seen only in control grafts.Conclusions: The coordinated early release of IL-1β and bFGF and the down-regulation of INFγ seem to trigger an inflammatory response, thereby initiating IH. The process then is propagated by the release of PDGF-AA and TNF-α, with concomitant smooth muscle cell proliferation and production of extracellular matrix. It is likely that this complex milieu of local paracrine signaling is required to generate the hyperplastic response seen in failing vein grafts. (J Vasc Surg 1996;24:463-71.)     

Shear force regulates matrix metalloproteinase activity in human saphenous vein organ culture

BACKGROUND: Development of vein graft intimal hyperplasia has been related both to shear force and to the activity of matrix metalloproteinases (MMPs). Little data are available regarding the effects of shear on MMP expression and activity. The aim of this study was to examine the relationship among shear force, metalloproteinase activity, and intimal thickening in human saphenous vein segments maintained in organ culture. MATERIALS AND METHODS: Segments of human saphenous vein were cultured under static conditions, or perfused under low-flow and high-flow conditions in a perfusion apparatus for 7 days. Metalloproteinase levels and activities were measured using ELISA and substrate gel zymography, respectively. Intimal thickening was determined by morphometric analysis. Results were compared with control vein tissue, which was not subjected to organ culture, using a one-way ANOVA. RESULTS: A 13% increase in proteolytic activity was noted on substrate gel zymography at 68-72 kDa in high-flow vein tissue. The protein content of MMP-2, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and TIMP-2 was increased in high-flow vein tissue by 21%, 126%, more than 100-fold, and 86%, respectively. In culture media bathing the outside of the vein, TIMP-2 was increased in high-flow specimens, while TIMP-1 was inversely related to flow rate. Intimal thickening was directly related to flow rates, and was progressively increased in the low-flow and high-flow groups by 3-fold and 4-fold, respectively. CONCLUSIONS: Metalloproteinase levels in human saphenous vein cultures are related to shear force. MMP levels and activity correlate with the degree of intimal thickening. This model may provide a valuable tool for the analysis of physical forces and their influence on intimal thickening in human saphenous vein.     

The effect of a venous anastomosis Tyrell vein collar on the primary patency of arteriovenous grafts in patients undergoing hemodialysis

PURPOSE: Vein collars and patches are used at the distal anastomoses of infrainguinal prosthetic grafts to improve graft patency. We initiated a randomized, prospective study to determine whether a Tyrell vein collar at the venous anastomosis of forearm loop arteriovenous grafts (AVGs) would improve patency. METHODS: Patients who required new forearm AVGs were randomized to (1) a standard end-to-side graft-vein anastomosis (control group) or (2) a Tyrell vein collar between the graft and the vein (study group). End points were (1) graft thrombosis, (2) graft removal and ligation, or (3) inadequate graft function. Randomization of 75 subjects was planned. The study was terminated early for ethical reasons. RESULTS: Seventeen patients (eight men, nine women) with a mean age of 52.8 years (range, 31-79 years) had 17 grafts placed (control group, n = 10; study group, n = 7). Comorbidities were not different between the groups (P>.05). Six (86%) of seven study grafts failed by 9 months (mean, 4.6 months). Four (66%) failed study grafts had venous outflow tract stenosis from intimal hyperplasia. This was confirmed at surgery in three and by angiography in one. The 9-month primary patency was 80% for the control group versus 17% for the study group (P =.015). Smaller outflow vein diameter in the study group (P =. 048) did not account for this inferior graft patency. CONCLUSION: A Tyrell vein collar at the venous anastomosis of a forearm AVG resulted in premature graft failure. The use of a Tyrell vein collar may accelerate venous anastomosis intimal hyperplasia.     

Early adaptation of human lower extremity vein grafts: wall stiffness changes accompany geometric remodeling

OBJECTIVE: To quantitatively describe the temporal changes in elastic properties and wall dimensions in lower-extremity vein grafts after implantation. DESIGN OF STUDY: This is a prospective study of patients (N = 38) undergoing lower extremity bypass grafts (N = 41) with autologous veins. Pulse wave velocity (PWV), luminal diameter, and wall thickness measurements were obtained by duplex ultrasound scan intraoperatively and at 1, 3, and 6 months postoperatively for assessment of graft dimensions and wall stiffness. RESULTS: Lower extremity vein grafts showed an increase in PWV (from 16 +/- 1 to 21 +/- 3 cm/s; mean +/- SEM; P =.08), reflecting an increase in wall stiffness (from 1.2 +/- 0.2 to 2.5 +/- 0.7 x 10(6) dynes/cm; P =.02) and wall thickness (from 0.47 +/- 0.03 to 0.61 +/- 0.004 mm; P =.04) over the first 6 months after implantation. Changes in lumen diameter were positively correlated with changes in external graft diameter (P <.01) and negatively correlated with initial lumen diameter (P <.01) but not with changes in the wall thickness. CONCLUSIONS: These results suggest complex remodeling of vein grafts during the first several months after implantation, with increased wall thickness occurring independent of variable changes in lumen diameter. Simultaneously, a marked increase in wall stiffness over this interval suggests a likely role for collagen deposition.     

Real-time polymerase chain reaction analysis reveals an evolution of cytokine mRNA production in allograft acceptor mice

BACKGROUND: The relative contribution of pro-inflammatory and anti-inflammatory cytokines in promoting the rejection or acceptance of experimental cardiac allografts remains controversial. We hypothesized that the posttransplantation induction of a new immune response to graft alloantigens at a distant delayed-type hypersensitivity (DTH) site would force the immune system to reveal its current disposition toward graft alloantigen as it initiates the new immune response. Thus, we should be able to monitor the evolution of the immunologic relationship between allograft recipients and their grafts at any time posttransplantation by challenging the recipient for DTH responses to donor alloantigen and evaluating the cytokine profiles displayed at the DTH site. METHODS: We have used the sensitive and quantitative technique of real-time polymerase chain reaction to evaluate the patterns of donor alloantigen-induced cytokine mRNA production for interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-10, and transforming growth factor (TGF)-beta. We evaluated cytokine mRNA expression in cardiac allografts and in donor alloantigen-challenged DTH sites in mice that have either accepted or rejected cardiac allografts. RESULTS: We observed the following. (1) Normal hearts and pinnae exhibited detectable baseline production of cytokine mRNAs: TGF-beta>IFN-gamma=IL-10>IL2->IL-4. (2) Both the accepted and rejecting cardiac allografts produced increased amounts of all cytokine mRNAs tested and displayed few quantitative differences in cytokine mRNA production. Notably, accepted allografts displayed enhanced IL-10 mRNA production on day 7 posttransplantation, but not on day 60 posttransplantation and reduced IFN-gamma mRNA production on day 60, but not day 7. (3) There was a high degree of variability in production levels among the various cytokine mRNAs, both for background levels and for allograft-stimulated levels. (4) Donor-reactive DTH sites of allograft rejector mice displayed a broad array of cytokine mRNAs, whereas the DTH sites of allograft acceptor mice displayed only IL-4 mRNA production. (5) Provision of exogenous TGF-beta or IL-10 at a DTH challenge site of allograft rejector mice caused a shift in the cytokine mRNA profile that minimized IFN-gamma and IL-2 mRNA production but spared IL-4, IL-10, and TGF-beta mRNA production. CONCLUSIONS: A broad array of cytokine mRNAs may be stockpiled for future use in cardiac allografts, regardless of whether the grafts will be accepted or rejected. This stockpile is continuously replenished for as long as the graft survives, thereby obscuring any changes in immune disposition of the graft recipient toward graft alloantigens. However, such changes can be revealed by challenge with donor alloantigens at a distant site (DTH challenge). In allograft acceptor mice, this disposition evolves from pro-inflammatory to anti-inflammatory.     

Early remodeling of lower extremity vein grafts: inflammation influences biomechanical adaptation

BACKGROUND: The remodeling of vein bypass grafts after arterialization is incompletely understood. We have previously shown that significant outward lumen remodeling occurs during the first month of implantation, but the magnitude of this response is highly variable. We sought to examine the hypothesis that systemic inflammation influences this early remodeling response. METHODS: A prospective observational study was done of 75 patients undergoing lower extremity bypass using autogenous vein. Graft remodeling was assessed using a combination of ultrasound imaging and two-dimensional high-resolution magnetic resonance imaging. RESULTS: The vein graft lumen diameter change from 0 to 1 month (22.7% median increase) was positively correlated with initial shear stress (P = .016), but this shear-dependent response was disrupted in subjects with an elevated baseline high-sensitivity C-reactive protein (hsCRP) level of >5 mg/L. Despite similar vein diameter and shear stress at implantation, grafts in the elevated hsCRP group demonstrated less positive remodeling from 0 to 1 month (13.5% vs 40.9%, P = .0072). By regression analysis, the natural logarithm of hsCRP was inversely correlated with 0- to 1-month lumen diameter change (P = .018). Statin therapy (beta = 23.1, P = .037), hsCRP (beta = -29.7, P = .006), and initial shear stress (beta = .85, P = .003) were independently correlated with early vein graft remodeling. In contrast, wall thickness at 1 month was not different between hsCRP risk groups. Grafts in the high hsCRP group tended to be stiffer at 1 month, as reflected by a higher calculated elastic modulus (E = 50.4 vs 25.1 Mdynes/cm2, P = .07). CONCLUSIONS: Early positive remodeling of vein grafts is a shear-dependent response that is modulated by systemic inflammation. These data suggest that baseline inflammation influences vein graft healing, and therefore, inflammation may be a relevant therapeutic target to improve early vein graft adaptation.     

Intestinal graft versus native liver cytokine expression in a rat model of intestinal transplantation: effect of donor-specific cell augmentation

INTRODUCTION: Immunomodulation by portal vein delivery of donor antigen reduces intestinal graft rejection. We investigated the impact of portal venous donor-specific cell augmentation (blood versus bone marrow) on cytokine expression in intestinal grafts versus native livers. METHODS: Ten groups of intestinal transplants (brown Norway male to Lewis female rats) varied by (1). the type of donor-specific cell augmentation and (2). the use and dose of tacrolimus-based immunosuppression. Tissue samples for histologic analysis and cytokine mRNA analysis were obtained at designated time points. RESULTS: Without immunosuppression, no type of cell augmentation reduced the rate of rejection. With immunosuppression, outcome was significantly better after portal donor-specific blood transfusion (versus bone marrow infusion). Irrespective of the type of cell augmentation, severe rejection caused strong intragraft expression of IL-1alpha, IL-1beta, IFN-gamma, and TNF-alpha; liver expression mainly involved TNF-alpha. Of note, nonimmunosuppressed, cell-augmented rats showed hardly any differences in cytokine expression in their grafts versus significant increases in their native livers. With immunosuppression, bone marrow infusion (versus blood transfusion) increased intragraft cytokine expression of IL-1alpha, IL-1beta, IFN-gamma, as well as TNF-alpha, and liver expression of IL-1beta. CONCLUSIONS: (1). Rejection and donor-specific cell augmentation independently caused differences in intragraft versus native liver cytokine expression after intestinal transplants. (2). Portal donor-specific blood transfusion (versus bone marrow infusion) lowered the incidence of rejection and diminished intragraft cytokine up-regulation. (3). In our study, TNF-alpha appeared to be the cytokine most strongly associated with rejection.     

Adenovirus-mediated gene transfer of human inducible nitric oxide synthase in porcine vein grafts inhibits intimal hyperplasia.

OBJECTIVE: The aim of this study is to determine whether adenoviral inducible nitric oxide synthase (iNOS) gene transfer could inhibit intimal hyperplasia (IH) in porcine internal jugular veins interposed into the carotid artery circulation. METHODS: Porcine internal jugular veins were transduced passively with 1 x 10(11) particles of an adenoviral vector carrying either the human iNOS (AdiNOS) or beta-galactosidase (AdlacZ) cDNA for 30 minutes and then interposed into the carotid artery circulation. Segments of each vein graft were maintained in an ex vivo organ culture to measure nitrite accumulation, a marker of nitric oxide synthesis. The grafts were analyzed immunohistochemically for the presence of neutrophils, macrophages, and leukocytes by staining for myeloperoxidase, ED1, and CD45, respectively, at 3 (n = 4) and 7 (n = 4) days. Morphometric analyses and cellular proliferation (Ki67 staining) were assessed at 3 (n = 4), 7 (n = 4), and 21 days (n = 8). RESULTS: AdlacZ-treated vein grafts demonstrated high levels of beta-galactosidase expression at 3 days with a gradual decline thereafter. Nitrite production from AdiNOS-treated vein grafts was approximately fivefold greater than AdlacZ-treated grafts (P =.00001). AdiNOS or AdlacZ treatment was associated with minimal graft inflammation. Cellular proliferation rates were significantly reduced in AdiNOS-treated grafts as compared with controls at both 3 (41%, P =.000004) and 7 days (32%, P =.0001) after bypass. This early antiproliferative effect was most pronounced at the distal anastomosis (65%, P =.0005). The iNOS gene transfer reduced the intimal/medial area ratio in vein grafts at 7 (36%, P =.009) and 21 days (30%, P =.007) versus controls. This inhibition of IH was again more prominent in the distal segments of the grafts (P =.01). CONCLUSION: Adenovirus-mediated iNOS gene transfer to porcine internal jugular vein grafts effectively reduced cellular proliferation and IH. Although iNOS gene transfer reduced IH throughout the entire vein graft, the most pronounced effect was measured at the distal anastomosis. These results suggest potential for iNOS-based genetic modification of vein grafts to prolong graft patency.     

Microsurgical anatomy of cerebral revascularization. Part I: anterior circulation

OBJECT: Revascularization is an important component of treatment for complex aneurysms that require parent vessel occlusion, skull base tumors that involve major vessels, and certain ischemic diseases. In this study, the authors examined the microsurgical anatomy of cerebral revascularization in the anterior circulation by demonstrating various procedures for bypass surgery. METHODS: Twenty-five adult cadaveric specimens were studied, using 3 to 40 magnification, after the arteries and veins had been perfused with colored silicone. The microsurgical anatomy of cerebral revascularization in the anterior circulation was examined with the focus on the donor, recipient, and graft vessels. The techniques discussed in this paper include the superficial temporal artery (STA)-middle cerebral artery (MCA), middle meningeal artery (MMA)-MCA, and side-to-side anastomoses; short arterial and venous interposition grafting; and external carotid artery/internal carotid artery (ICA)-M2 and ICA-ICA bypasses. Bypass procedures for cerebral revascularization are divided into two categories depending on their flow volume: low-flow and high-flow bypasses. A low-flow bypass, such as the STA-MCA anastomosis, is used to cover a relatively small area, whereas a high-flow bypass, such as the ICA-ICA anastomosis, is used for larger areas. Cerebral revascularization techniques are also divided into two types depending on the graft materials: pedicled arterial grafts, such as STA and occipital artery grafts, and free venous or arterial grafts, which are usually saphenous vein and radial artery grafts. Pedicled arterial grafts are mainly used for low-flow bypasses, whereas venous or arterial grafts are used for high-flow bypasses. CONCLUSIONS: It is important to understand the methods of bypass procedures and to consider indications in which cerebral revascularization is needed.     

Purine and cytokine concentrations in the renal vein of the allograft during reperfusion

The impairment of organ function derived from ischemia-reperfusion injury is still an important problem in solid organ transplantation. Cell alterations induced by ischemia prime the tissue for subsequent damage during the reperfusion phase. The aim of present study was to examine the association between changes in cytokine and purine metabolite concentrations in graft renal vein during reperfusion. The study included 17 recipients of cadaveric renal grafts: 10 men and seven women of overall mean age of 49 +/- 7 years and cold ischemia time 25 +/- 3 hour. The levels of interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-10, interferon (INF)-gamma, tumor necrosis factor (TNF)-beta, and TNF-alpha in renal graft vein plasma during 5 first minutes of reperfusion were quantified by flow cytometry. Increased concentrations of IL-6, TNF-alpha, and IL-1beta were observed during reperfusion. The IFN-gamma concentrations correlated negatively with xanthine (Xan) concentrations in renal vein blood during reperfusion, whereas there was a positive correlation between IL-2 and Xan concentrations. Moreover, the concentrations of IL-6 and IL-10 correlated negatively with hypoxanthine concentrations, and the concentrations of IL-4 also correlated negatively with Xan concentrations. The results of this study indicated the enhanced release of some cytokines during kidney graft reperfusion. It occurred in association with release of purine metabolites-the markers of energy status of renal tissue. Therefore, the enhanced cytokine production during reperfusion might influence ischemia-reperfusion injury and the early graft function.     

Correlation of long-term results of femoropopliteal autogenous vein grafts with shear stress variation. In situ or reversed graft?

To investigate the correlation between blood flow rate and shear stress variation (tau-variation), the integral of time differential of wall shear stress in one cardiac cycle and the outcome of the vein graft, 42 consecutive patients with femoropopliteal autovein grafts (24 in situ and 18 reversed grafts) were followed for 3 months to 5 years after surgical repair. No correlation was noted between the intraoperative blood flow rate and the outcome of the vein grafts with either procedure. In contrast, the tau-variation value of the vein grafts was closely related to their outcome with both procedures. The higher the tau-variation, the better the long-term results. Vein grafts with a tau-variation of over 60 dyn/cm2 showed good long-term results. The in situ grafts tended to have a higher tau-variation than the reversed grafts (67% in the in situ grafts vs 39% in the reversed grafts). Late failures were noted in vein grafts with low tau-variation value within 3 years after surgery. We recommend the in situ graft technique for patients undergoing femoropopliteal reconstruction, with careful follow-up in cases of vein grafts with a low tau-variation value.     

Monocyte adhesion to human vein grafts: a marker for occult intraoperative injury?

OBJECTIVE: Monocyte adhesion to the vessel wall is believed to be an important initiating event in atherosclerosis and intimal hyperplasia. We hypothesized that occult intraoperative vein injury induces an immediate increase in monocyte adhesion that may be critical to the development of vein graft disease. METHODS: Vein segments were obtained from patients (n = 23) undergoing lower extremity bypass. The initial segment (V1, n = 17) was excised immediately at the time of conduit harvest. A second segment (V2, n = 23) was obtained from the distal conduit just before performing the distal anastomosis. Segments were incubated with radiolabeled THP-1 cells (monocytoid cell line) for 1 hour at 37 degrees C, then rinsed and solubilized for determination of bound radioactivity. In a subset of grafts (n = 4), THP-1 cells were preincubated with monoclonal antibody (mAB) 7E3 (which binds to the monocyte integrin Mac-1 at its fibrinogen [Fg]-binding site) or control (mAB 14E11). Fg deposition and endothelial coverage were evaluated by immunohistochemistry (n = 10). Statistical analysis was performed using the paired t test and analysis of variance. Follow-up graft patency data were obtained and correlated with adhesion values using an exact test (StatXact, Cytel Software, Cambridge, Mass). RESULTS: Monocyte adhesion was significantly increased after surgical manipulation (V1, 2400 +/- 770 versus V2, 7343 +/- 1555 cells/cm(2); P <.02). Fg deposition was abundant in V2 sections and not seen in V1. Monocyte adhesion to V2 segments was significantly reduced (58% of control, P <.01) by 7E3 treatment. Graft follow-up was complete with a mean interval of 11 months. Higher V2 adhesion values were associated with occluded grafts (P =.07). The median value for the six occluded grafts was 6234 cells/cm(2) versus 3892 cells/cm(2) for the 17 patent grafts. CONCLUSIONS: Monocyte adhesion to the vein wall is immediately increased after surgical manipulation and is inhibited by mAB 7E3. Early monocyte adhesion to vein grafts is likely to involve interactions between Mac-1 and Fg. Heightened levels of monocyte adhesion at implantation may be a marker for subsequent vein graft failure.     

The consequences of a failed femoropopliteal bypass grafting: comparison of saphenous vein and PTFE grafts

OBJECTIVES: Although there are numerous reports comparing saphenous vein (SV) and polytetrafluoroethylene (PTFE) with respect to the patency rates for femoropopliteal bypass grafts, the clinical consequences of failed grafts are not as well described. This study compares the outcomes of failed SV and PTFE grafts with a specific emphasis on the degree of acute limb ischemia caused by graft occlusion. METHODS: Over a 6-year period, 718 infrainguinal revascularization procedures were performed, of which 189 were femoropopliteal bypass grafts (SV, 108; PTFE, 81). Society for Vascular Surgery/International Society for Cardiovascular Surgery (SVS/ISCVS) standardized runoff scores were calculated from preoperative arteriograms. Clinical categories of acute limb ischemia resulting from graft occlusion were graded according to SVS/ISCVS standards (I, viable; II, threatened; III, irreversible). Primary graft patency and limb salvage rates at 48 months were calculated according to the Kaplan-Meier method. RESULTS: Patients were well matched for age, sex, and comorbidities. Chronic critical ischemia was the operative indication in most cases (SV, 82%; PTFE, 80%; P =.85). Runoff scores and preoperative ankle-brachial index measurements were similar for the two groups (SV, 6.0 +/- 2.5 [SD] and 0.51 +/- 0.29; PTFE, 5.3 +/- 2.8 and 0.45 +/- 0.20; P =.06 and P =.12). The distal anastomosis was made below the knee in 60% of SV grafts and 16% of PTFE grafts (P <.001). Grade II ischemia was more likely to occur after occlusion of PTFE grafts (78%) than after occlusion of SV grafts (21%; P =.001). Emergency revascularization after graft occlusion was required for 28% of PTFE failures but only 3% of SV graft failures (P <.001). Primary graft patency at 48 months was 58% for SV grafts and 32% for PTFE grafts (P =.008). Limb salvage was achieved in 81% of SV grafts but only 56% of PTFE grafts (P =.019). CONCLUSIONS: Patients undergoing femoropopliteal bypass grafting with PTFE are at greater risk of ischemic complications from graft occlusion and more frequently require emergency limb revascularization as a result of graft occlusion than patients receiving SV grafts. Graft patency and limb salvage are superior with SV in comparison with PTFE in patients undergoing femoropopliteal bypass grafting.