Outcome of Femoral Angioplasty/Stenting Procedures in Different Ethnic Groups in England: A Retrospective Analysis of Hospital Episode Statistics and Review of Literature.

PURPOSE: Various studies, mainly from North America, report worse outcomes in ethnic minority populations submitted to revascularization for peripheral arterial disease (PAD). Limited nationwide data in relation to ethnicity are available from Europe. OBJECTIVE: The objective of the study is to compare the outcomes of femoral angioplasty/stenting procedures among different ethnic groups in England during the 10-year period from 2006 to 2015. MATERIALS AND METHODS: The "Hospital Episode Statistics" database has been searched using International Classification of Diseases, Tenth Revision (ICD-10) codes to identify all cases of femoral angioplasty or stenting from English NHS Hospitals between January 1, 2006, and December 31, 2015. Subsequent mortality, second open or endovascular infrainguinal procedures, and major amputations on the same side within 2 years after the first procedure have been recorded. Patients were broadly categorized according to ethnicity as whites, Asians, and blacks. Chi-square test was used to demonstrate significant differences among ethnic groups and odds ratios (ORs) were calculated using white ethnic group as reference. RESULTS: A total number of 70 887 femoral endovascular procedures were recorded in patients from the 3 ethnic groups. Two-year mortality in whites, Asians, and blacks was 18.3%, 22.1%, and 19.5% (p<0.001); rates of second endovascular procedure were 12.1%, 13.1%, and 13.5% (p=0.24); rates of open infrainguinal procedure were 5.6%, 4.5%, and 8.0% (p<0.001); and rates of major amputation were 4.8%, 4.1%, and 7.0% (p<0.001), respectively. Mortality was higher in Asians (OR=1.26, 95% confidence interval [CI]=1.10-1.45, p<0.01) compared with whites. On the contrary, blacks underwent more open arterial operations (OR=1.48, 95% CI=1.19-1.83, p<0.01) and more amputations (OR=1.49, 95% CI=1.18-1.87, p<0.01). There were no significant differences in the rates of second endovascular procedures. CONCLUSION: Two-year mortality after femoral angioplasty/stenting is higher in Asians, whereas risk of limb loss is higher in blacks compared with whites. Reasons of these ethnic differences in outcomes following femoral endovascular procedures for PAD merit further study.

The Impact of Atrial Fibrillation on Outcomes of Peripheral Arterial Disease: Analysis of Routinely Collected Primary Care Data.

BACKGROUND: The combination of peripheral arterial disease and atrial fibrillation is linked with high risk of mortality and stroke. This study aims to investigate the impact of atrial fibrillation on patients with diagnosed peripheral arterial disease. METHODS: This is a retrospective study using The Health Improvement Network database, which contains prospectively collected data from participating primary care practices. Patients with a new diagnosis of peripheral arterial disease between January 8, 1995 and January 5, 2017 were identified in the database alongside relevant demographic information, clinical history, and medications. Every patient in the dataset with peripheral arterial disease and baseline atrial fibrillation (case) was matched to a patient without atrial fibrillation (control) with similar characteristics using propensity score matching. Cox-regression analysis was performed and hazard ratios (HR) calculated for the outcomes of death, stroke, ischemic heart disease, heart failure, and major amputation. RESULTS: Prevalence of atrial fibrillation in this cohort was 10.2%. All patients with peripheral arterial disease and atrial fibrillation (n = 5685) were matched with 5685 patients without atrial fibrillation but otherwise similar characteristics. After multivariate analysis, atrial fibrillation was independently associated with mortality (HR 1.18; 95% confidence interval [CI], 1.12-1.26; P < .01), cerebrovascular events (HR 1.35; 95% CI, 1.17-1.57; P < .01), and heart failure (HR 1.87; 95% CI, 1.62-2.15; P < .01), but not with ischemic heart disease or limb loss. CONCLUSION: In peripheral arterial disease patients, atrial fibrillation is a risk factor for mortality, stroke, and heart failure. This emphasizes the need for proactive surveillance and holistic management of these patients.

Outcome of Femoral-popliteal Bypass Procedures in Different Ethnic Groups in England: A Retrospective Analysis of Hospital Episode Statistics.

BACKGROUND: Previous studies, mainly from the United States, have reported worse outcomes from lower limb bypass procedures in ethnic minority populations. Limited nationwide data are available from ethnic minority populations from Europe. The aim of this study is to investigate outcomes from lower limb bypass procedures in ethnic minorities from England. METHODS: We enquired the "Hospital Episode Statistics" database, using ICD-10 codes to identify all cases of femoral-popliteal bypass operations from English NHS Hospitals from 01/01/2006 to 31/12/2015. Every case was followed up for 2 years for subsequent events. The primary outcomes were mortality and major leg amputation. Patients were broadly categorised according to Black, Asian and White ethnicity. Chi-square test was used to the ethnic groups and odds ratios (OR) were calculated using White ethnic group with the largest numbers of participants as a reference category. RESULTS: In the examined 10-year period, 20825 femoral-popliteal bypass procedures (250 of Black, 167 of Asian, and 20.408 of White ethnicity) were recorded. Thirty-day and 2-year mortality were 2.8% and 16.8% with no significant ethnic differences. Patients of Black ethnicity had higher risk of limb loss compared to Whites (23.2% vs. 15.6%, OR = 1.63, 95% confidence interval (CI) 1.21-2.19, P < 0.01). There was no significant difference in amputation rates between Asians and Whites (16.2% vs.. 15.6%, P = 0.94). CONCLUSIONS: Patients of Black ethnicity are at higher risk of limb loss after a femoropopliteal bypass procedure. Further research is needed to identify the causes of this discrepancy.

Peripheral Arterial Disease in Patients with Atrial Fibrillation: The AFFIRM Study.

BACKGROUND: Peripheral arterial disease has been linked with worse outcomes in patients with atrial fibrillation. The aim of this study is to assess the impact of peripheral arterial disease on mortality and stroke in a cohort of patients with atrial fibrillation. METHODS: This was an ancillary analysis of the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial. A comparison of baseline characteristics was made between patients with atrial fibrillation with and without diagnosed peripheral arterial disease. Multivariate cox regression analysis was performed to compare the risk of stroke, death, and cardiovascular death among the two groups. RESULTS: The prevalence of peripheral arterial disease in the whole cohort of 4060 patients with atrial fibrillation was 6.7%. Patients with peripheral arterial disease tended to be older; had higher prevalence of diabetes mellitus, hypertension, and smoking; and were more likely to have a history of coronary artery disease, heart failure, cardiac surgery or cardiac intervention, and stroke or transient ischemic attack (all P < .05). After multivariate adjustment, peripheral arterial disease was significantly associated with overall higher mortality (hazard ratio 1.34, 95% confidence interval 1.06-1.70, P = .016) in patients with atrial fibrillation, but the rates of ischemic stroke were similar in the two groups (3.9% vs 3.5%, P = 0.874). Subgroup analysis confined to the patients with non-anticoagulated atrial fibrillation showed that peripheral arterial disease was an independent predictor of ischemic stroke (hazard ratio 3.37, 95% confidence interval 1.25-9.09, P < .016). CONCLUSION: Peripheral arterial disease predicts higher mortality in atrial fibrillation, and was an independent predictor of ischemic stroke in patients with non-anticoagulated atrial fibrillation. Proactive surveillance and optimization of medical management in this group of patients is warranted, given the high risks associated with peripheral arterial disease where atrial fibrillation is also present.

The Relationship Between Serum Interleukin-1α and Asymptomatic Infrarenal Abdominal Aortic Aneurysm Size, Morphology, and Growth Rates.

OBJECTIVE/BACKGROUND: In a pilot study, a relationship between abdominal aortic aneurysm (AAA) diameter and serum interleukin (IL)-1α levels was reported, and that endothelial cell (EC) activation in vitro in response to serum from patients with AAA was blocked by anti-IL-1α antibodies. The aim of the present study was to further investigate the relationship between serum IL-1α and asymptomatic infrarenal AAA size, morphology, and growth rates. METHODS: Serum IL-1α was measured using enzyme linked immunosorbent assay in 101 patients with asymptomatic, infrarenal AAA and related to aneurysm size, morphology, and growth rates. RESULTS: IL-1α was measured in 101 patients. There was no statistically significant difference in mean age between men and women. IL-1α was detectable in 62.4% of patients; median IL-1α titre was 3.26 pg/mL. There was no statistically significant relationship between IL-1α and maximum AAA antero-posterior diameter as measured by ultrasound (p = .649), AAA morphology (aortic length [p = .394], sac [p = .369], and thrombus volume [p = .629]) as measured on computed tomography, absolute increase in AAA diameter (p = .214), or AAA growth rate (p = .230). CONCLUSION: IL-1α is detectable in the majority of patients with infrarenal AAA, but the cause and clinical significance of this novel observation remains unknown.

Comparison of 2 Sample Processing Methods and 9 Commercial Immunoassays for the Detection of Interleukin-1α in the Serum of Patients with Abdominal Aortic Aneurysm.

BACKGROUND: For a cytokine to have a role as a clinically useful biomarker, it must be measureable in a practical, reliable, and reproducible manner. Furthermore, assays from different manufacturers should produce comparable results. The aim of this paper was to examine the effect of 2 sample processing methodologies and compare 9 commercially available immunoassays for their measurement of serum interleukin (IL)-1α in patients with abdominal aortic aneurysm. METHODS: Two sample processing methodologies and 9 manufacturers' immunoassays were compared. Each immunoassay was also tested for detection of both IL-1α isoforms. RESULTS: A positive signal for IL-1α was found in all serum samples, in all immunoassays, using both processing methods. In the majority, titer concentrations were unquantifiable with values below manufacturers' detectable range. Variability in titer concentrations was seen across all immunoassays. With the exception of 1 immunoassay, all were able to detect both IL-1α isoforms. CONCLUSIONS: Researchers wishing to measure serum cytokines levels should be aware that differences in sample processing methods and manufacturers' immunoassays can affect the results. This may result in misleading conclusions being drawn about biological processes underpinning a wide range of inflammatory diseases.

Ethnic differences in the prevalence of peripheral arterial disease: a systematic review and meta-analysis.

BACKGROUND: Previous studies have demonstrated higher rates of peripheral arterial disease (PAD) in blacks and lower in Asians compared to whites. The aim of this study is to undertake a comprehensive review of literature on ethnic differences in the epidemiology of PAD. METHODS: A systemic review and meta-analysis included studies reporting PAD prevalence in general or diabetic populations, and comparing PAD prevalence in ethnic groups. RESULTS: Mean prevalence of PAD in general population for whites, blacks and Asians was 3.5%, 6.7% and 3.7% respectively. Meta-analysis demonstrated higher prevalence of PAD in blacks (p < 0.001) and lower amongst Asians (p < 0.001), compared to whites. In diabetic population, the mean prevalence of PAD for whites, blacks, east Asians and south Asians was 17%, 25.3%, 13.5% and 7.6% respectively. In diabetic population, south Asians had a lower PAD prevalence (p < 0.001) compared to whites; there was no significant difference between blacks and whites. Overall females have higher PAD rates, in general (3.8% vs 3.2%; p < 0.001) and in diabetic population (13.7% vs 10%; p < 0.001). CONCLUSION: Blacks are vulnerable to PAD, in contrast to Asians who have lower prevalence of PAD when compared to whites. Further research is needed in order to identify the factors that generate this difference.

Assessment of renal function by means of cystatin C following standard and fenestrated endovascular aneurysm repair.

BACKGROUND: Cystatin C (Cyst C) is more sensitive marker for early renal injury. However, serum creatinine (sCr) and estimated glomerular filtration rate (eGFR) are still used as the standard renal markers after endovascular aortic aneurysm repair (EVAR). The goal of this study was to compare the efficacy of Cyst C, sCr, and eGFR as markers of renal function after EVAR. PATIENTS AND METHODS: This study examined 29 patients (27 men) with a mean age of 76.9 years (range, 55-89 years) undergoing standard (n = 19) and fenestrated (n = 10) EVAR for abdominal aortic aneurysm (AAA) of mean diameter 6.9 cm (range, 5.5-10 cm). Cyst C and sCr were measured and eGFR calculated before and 1 day and 1, 6, and 12 months after EVAR. RESULTS: At 24 hours after procedure, a significant increase in Cyst C (P < 0.005) and sCr (P = 0.028) and significant decrease in eGFR (P = 0.04) were seen. Cyst C continued to increase and was significantly higher at 1 (P < 0.002), 6 (P < 0.005), and 12 (P < 0.005) months compared with baseline. By contrast, sCr and eGFR did not show any significant change at 1, 6, and 12 months from the baseline level. Cyst C increased significantly postoperatively regardless of the baseline renal function. None of the patients required renal replacement therapy. CONCLUSIONS: EVAR is associated with a significant increase in Cyst C starting 24 hours after the procedure and is maintained for 12 months. sCr and eGFR only show significant change at 24 hours and therefore may underestimate long-term renal damage after EVAR.

Effect of endovascular and open abdominal aortic aneurysm repair on thrombin generation and fibrinolysis.

BACKGROUND: Abdominal aortic aneurysm (AAA) is associated with a prothrombotic diathesis that may increase the risk of cardiovascular events. This diathesis is exacerbated in the short term by open aneurysm repair (OAR) and endovascular aneurysm repair (EVAR). However, the effect of EVAR and OAR on coagulation and fibrinolysis in the medium and long term is poorly understood. The purpose of this study was to investigate the medium-term effects of EVAR and OAR on thrombin generation, neutralization, and fibrinolysis. METHODS: Prothrombin fragment (PF)1+2, thrombin antithrombin (TAT) complex, plasminogen activator inhibitor (PAI) activity, and tissue-plasminogen activator (t-PA) antigen were measured in eight age-matched controls (AMCs), 29 patients with AAA immediately before (preoperatively) and 12 months after EVAR (post-EVAR), and in 11 patients at a mean of 16 months after OAR (post-OAR). RESULTS: Preoperatively, PF1+2 levels were significantly higher in patients with AAAs than in AMC. PF1+2 levels post-EVAR and post-OAR were significantly lower than preoperative values and similar to AMC. There was no significant difference in TAT, PAI, or t-PA between AMC, AAA preoperatively, and post-EVAR. Post-OAR, PAI activity was significantly higher than in preoperative patients. CONCLUSIONS: AAA is associated with increased thrombin generation without upregulation of fibrinolysis. The prothrombotic, hypofibrinolytic diathesis observed in patients with AAA returns toward normal in the medium term after EVAR and OAR, although there is a trend toward decreased fibrinolysis post-OAR.

The relationship between aortic aneurysm sac thrombus volume on coagulation, fibrinolysis and platelet activity.

AIM: Abdominal aortic aneurysm (AAA) is associated with chronic mural inflammation and a pro-thrombotic diathesis. It has been suggested that both may be related to biologically active intra-sac thrombus. The aim of this study was to examine the relationship between thrombin generation, fibrinolysis, platelet activity and AAA sac thrombus volume. METHODS: 30 patients (29 men) of median (IQR) age 75 (71-82) years with an infra-renal AAA >5.5 cm in antero-posterior diameter were prospectively studied. AAA, lumen and thrombus volumes were calculated using a CT workstation (Vitrea). Plasma thrombin-antithrombin (TAT), plasminogen activator inhibitor (PAI)-1, and soluble (s) P-selectin were measured as biomarkers of coagulation, fibrinolysis and platelet activity, respectively RESULTS: Median (IQR) AAA total, lumen and thrombus volumes were 188 (147-247) cm(3), 80 (54.3-107) cm(3) and 97.6 (63-127) cm(3) respectively. TAT levels were significantly higher (median, QR, 7.15 [4.7-31.3] µg/L, p=<0.001) and sP-selectin levels significantly lower (median, IQR, 80.5 [68-128] ng/ml, p=<0.0001) than the normal range. PAI-1 levels (median, IQR, 20.9 [8.4-50.7] ng/ml) were normal. There was no correlation between AAA thrombus volume and PAI-1 (r=-0.25, p=0.47), sP-Selectin (r=0.26, p=0.43) or TAT plasma levels (r=-0.21, p=0.54). CONCLUSION: The present study confirms that patients with AAA demonstrate haemostatic derangement, but the extent of the haemostatic derangement does not correlate with AAA sac thrombus volume.

Changes in thrombin generation, fibrinolysis, platelet and endothelial cell activity, and inflammation following endovascular abdominal aortic aneurysm repair.

BACKGROUND: Abdominal aortic aneurysm (AAA) is a chronic inflammatory condition associated with a prothrombotic, hypofibrinolytic diathesis that may increase the risk of cardiovascular events. The effect of endovascular aneurysm repair (EVAR) on this prothrombotic diathesis is not fully understood, especially over the medium and long term. A better understanding of these postintervention changes may improve the risk of cardiovascular complications in the long term. The purpose of this study was to examine thrombin generation, fibrinolysis, platelet and endothelial activation, and the inflammatory response during the 12 months following EVAR. METHODS: Twenty-nine patients (mean age, 76.9 years) undergoing EVAR for AAA (mean diameter 6.9 cm) had prothrombin fragment (PF) 1 + 2, thrombin-antithrombin complex (TAT), plasminogen activator inhibitor (PAI) activity, tissue plasminogen activator (t-PA) activity and antigen, soluble P- and E-selectin, and highly sensitive C-reactive protein (hsCRP) measured before and at 24 hours, and 1, 6, and 12 months after surgery. RESULTS: PF1 + 2 were markedly elevated prior to EVAR and remained so at 24 hours and 1 month, but had decreased significantly at 6 and 12 months. TAT was also elevated prior to EVAR and increased still further by 24 hours, but fell to below baseline levels thereafter. PAI activity and t-PA antigen were normal prior to EVAR, increased significantly at 24 hours, and then fell to baseline levels. t-PA activity was only detectable at 1 and 6 months; there was a significant rise in soluble P- and E-selectin after EVAR, which was sustained for 12 months. hsCRP increased transiently in response to EVAR but returned to preoperative levels by 1 month. CONCLUSIONS: The prothrombotic, hypofibrinolytic diathesis associated with AAA is normalized 12 months after EVAR. This beneficial systemic effect of EVAR for AAA disease may help protect patients against future thromboembolic cardiovascular events.

Coagulation, fibrinolysis, and platelet activation in patients undergoing open and endovascular repair of abdominal aortic aneurysm.

BACKGROUND: Endovascular aneurysm repair (EVAR) is associated with an improved perioperative mortality compared to open surgical repair. This benefit may reflect reduced incidence of microvascular and macrovascular thrombotic complications after EVAR. PURPOSE: The purpose of this study was to review and compare the effects of abdominal aortic aneurysm (AAA), open surgical repair, and EVAR on coagulation, fibrinolysis, and platelet activation. METHODS: A MEDLINE (1966-2010) and Cochrane library search for articles relating to the effects of AAA, open surgical repair, and EVAR on hemostasis was performed utilizing and cross-linking terms such as clotting, fibrinolysis, AAA, EVAR, and open surgical repair. Studies with a small cohort of patients (less than 7) or in which values of assessed biomarkers were not included were rejected. RESULTS: AAA is associated with increased thrombin generation, activity, and fibrin turnover as evidenced by increased plasma levels of thrombin-antithrombin III-complex (TAT), activated protein C-protein C inhibitor (APC-PCI), fibrin-monomer-fibrinogen (FM-F), F1+2, fibrinogen, and D-dimer. The extent of hemostatic derangement correlates with the volume of intraluminal thrombus. This procoagulant state is exaggerated in the immediate perioperative period after both open surgical repair and EVAR, but is attenuated at medium-term follow-up although not normalized. CONCLUSION: The resultant prothrombotic diathesis after open surgical repair and EVAR may account for the high level of perioperative thrombotic complications.

Perioperative myocardial injury and hemostasis in patients undergoing endovascular aneurysm repair for asymptomatic infrarenal abdominal aortic aneurysm.

OBJECTIVE: (1) To report the incidence of myocardial injury in patients undergoing endovascular aortic aneurysm repair (EVAR) through the routine measurement of perioperative cardiac troponin-T (cTnT) and (2) to investigate and correlate changes in perioperative cTnT levels with any concomitant hemostatic derangement. METHODS: Prospective study of 30 patients undergoing elective EVAR for infrarenal abdominal aortic aneurysm. Cardiac TnT was assayed at 24 hours postoperatively. Plasma thrombin antithrombin III complex (TAT), plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (t-PA) activity, and soluble P-selectin (sP-selectin) were assayed preoperatively and at 24 hours postoperatively. RESULTS: Five (17%) patients demonstrated elevated cTnT levels at 24 hours; 3 patients had no clinical evidence of myocardial injury. There was a positive correlation between cTnT and TAT levels at 24 hours post-EVAR (r = .38, P = .039, Kendall-tau B = 0.26). CONCLUSIONS: Endovascular aortic aneurysm repair is associated with a significant risk of perioperative myocardial injury that is underdetected clinically and associated with a procoagulopathic state.

Carotid artery pseudoaneurysm after carotid endarterectomy: case series and a review of the literature.

BACKGROUND: Pseudoaneurysm (PA) after carotid endarterectomy (CEA) is a rare complication with incidence less than 1%. There is a potential for rupture, embolization, thrombosis or compression of cranial nerves. OBJECTIVE: We reviewed our experience and compare it to the literature to raise awareness of this rare though serious condition. It is crucial to treat these patients early to avoid the hazardous consequences. METHODS: A review of the case records of patients who had CEA at University Hospital Birmingham (UHB) NHS Foundation Trust from 1990-2007, was undertaken. Information of patients including their aetiology, presenting features, treatment and results was collected. The English-language literature was searched using PubMed database for post CEA pseudoaneurysm. RESULTS: Five patients developed post CEA PA. This represents 0.4% of the 1200 CEA performed at our hospital in the last 18 years. The timing of their presentation varied from three days to eight months after the original operation. All had patch reconstruction after CEA. Patches were intact at exploration of the PAs. There was one death and one stroke. The literature revealed 154 carotid PAs after CEA and two cases following carotid stenting 52 of these cases had infected PA. Patients with synthetic patches have the least incidence of infection. More than 80% had open surgery and 9% had endovascular repair. CONCLUSION: Post CEA surveillance is necessary to detect patients with PA early. Factors that favour infection must be avoided. Endovascular repair of carotid PA should be encouraged in specialised centres.

Surgical versus endovascular reconstruction for chronic mesenteric ischemia: a contemporary UK series.

OBJECTIVE: To assess the outcome of surgical (SR) and endovascular (ER) reconstruction for chronic mesenteric ischemia (CMI). METHODS: Retrospective review of consecutive patients who underwent SR or ER for CMI in 3 UK vascular surgery units between 1996 and 2006. Early (<30 days; technical success, morbidity, mortality, length of hospital stay) and late (>30 days) outcomes (symptom recurrence, vessel/graft patency, reintervention, mortality) were assessed. RESULTS: A total of 27 patients underwent 32 reconstructions (SR = 17, ER = 15). A total of 44 of 56 (79%) diseased arteries underwent SR (n = 26; bypass = 24, reimplantation = 2; occlusion = 16, stenosis = 10) or ER (n = 18; stenosis = 16, occlusion = 2). Perioperative mortality for SR and ER was 6% and 0%, respectively (P > or = .99). Hospital stay was shorter following ER (mean, 4.3 vs. 14.2 days, P = .0003). Mean (range) follow-up for SR and ER was 34 (1-94) and 34 (0-135) months, respectively. At 2 years, SR demonstrated superior secondary patency (100% vs. 65%) and clinical patency (100% vs. 73%). CONCLUSIONS: Surgical mesenteric reconstruction is associated with significantly longer hospital stay, but superior long-term outcome compared to endovascular reconstruction.

Failure of endovascular stenting for popliteal cystic disease.

We describe an attempted endovascular stenting for popliteal artery stenosis secondary to adventitial cystic disease in a 56-year-old man with lifestyle-limiting claudication. Despite technical success, it remained patent only for 1 week, requiring interposition venous graft reconstruction eventually.

Inflammatory responses of endothelial cells experiencing reduction in flow after conditioning by shear stress.

Exposure of endothelial cells (EC) to shear stress reduces their response to tumour necrosis factor-alpha (TNF). We tested how shear-conditioned EC responded to reduction in flow, either by spontaneously binding leukocytes, or by increasing sensitivity to TNF. Human umbilical vein EC were exposed to shear stress of 2.0 Pa (20 dyn/cm(2)) for 24 h. Shear was then reduced to stasis (30 sec perfusion each hour to exchange medium) or 0.003 Pa (creeping flow). At chosen times, neutrophils were perfused over the EC at 0.1 Pa (effective reperfusion). EC developed an ability to capture flowing neutrophils that lasted from 1 to 3 h after flow reduction, which was reduced by antibody against P-selectin or pre-treatment of EC with an inhibitor of NADPH-oxidase. Adhesion of neutrophils to TNF-treated EC was greatly suppressed by shear-conditioning, remained suppressed immediately after cessation of flow and then took 48 h to approach the level in static cultures. Interestingly, the response to TNF remained suppressed in cultures switched to creeping flow. Gene array analysis confirmed that differently recovered cells had separate phenotypes. Thus, an acute response of EC to reduction in shear may contribute to leukocyte recruitment, along with hypoxia, in ischaemia and reperfusion. Prolonged cessation of flow may increase the sensitivity of EC to inflammatory stimuli, but this effect may be suppressed by residual flow.

Mechanisms of the anti-inflammatory effects of hydroxyethyl starch demonstrated in a flow-based model of neutrophil recruitment by endothelial cells.

OBJECTIVE: To determine whether plasma volume expander hydroxyethyl starch (HES) may protect against reperfusion injury through an ability to reduce neutrophil recruitment. DESIGN: An in vitro study using paired comparisons of adhesion of flowing neutrophils. SETTING: A collaboration between clinical and basic science departments in a university hospital. SUBJECTS: Neutrophils and cultured human umbilical vein endothelial cells (HUVEC). INTERVENTIONS: Treatment with HES (average molecular weight of 200 kd and substitution of 0.62) at clinically relevant concentrations or with gelatin solution (average molecular weight of 30 kDa) of comparable viscosity. MEASUREMENTS AND MAIN RESULTS: Glass capillaries were coated internally with either purified adhesion molecules or HUVEC, which were treated with tumor necrosis factor-alpha in the presence or absence of HES. Neutrophils were perfused over these surfaces (with or without HES) and their recruitment quantified by video microscopy. Expression of adhesion molecules and of the chemokine interleukin-8 by HUVEC were analyzed by enzyme-linked immunosorbent assay and quantitation of messenger RNA. HES over a wide range of concentrations had no effect on selectin- or integrin-mediated adhesion of neutrophils. However, when HUVEC were cultured with 1.5% wt/vol HES, neutrophil capture induced by low-dose (1 unit/mL) tumor necrosis factor-alpha and transendothelial migration induced by high-dose (100 units/mL) tumor necrosis factor-alpha were significantly inhibited (p < .05, in each case). The effects were linked with reductions in expression of E-selectin and interleukin-8 by HUVEC at these respective tumor necrosis factor-alpha concentrations (p < .05, in each case). Gelatin (2% wt/vol) had no significant effect in assays with HUVEC. CONCLUSIONS: Application of HES to HUVEC exerts an inhibitory effect on different stages of neutrophil recruitment, depending on the level of the inflammatory stimulus. These effects are associated with reduced adhesion molecule expression and chemokine production. In vivo, comparable effects might protect against complications associated with reperfusion injury.

Identification of a phenotypically and functionally distinct population of long-lived neutrophils in a model of reverse endothelial migration.

Recent studies have demonstrated that neutrophils are not a homogenous population of cells. Here, we have identified a subset of human neutrophils with a distinct profile of cell-surface receptors [CD54(high), CXC chemokine receptor 1(low) (CXCR1(low))], which represent cells that have migrated through an endothelial monolayer and then re-emerged by reverse transmigration (RT). RT neutrophils, when in contact with endothelium, were rescued from apoptosis, demonstrate functional priming, and were rheologically distinct from neutrophils that had not undergone transendothelial migration. In vivo, 1-2% of peripheral blood neutrophils in patients with systemic inflammation exhibit a RT phenotype. A smaller population existed in healthy donors ( approximately 0.25%). RT neutrophils were distinct from naïve circulatory neutrophils (CD54(low), CXCR1(high)) and naïve cells after activation with formyl-Met-Leu-Phe (CD54(low), CXCR1(low)). It is important that the RT phenotype (CD54(high), CXCR1(low)) is also distinct from tissue-resident neutrophils (CD54(low), CXCR1(low)). Our results demonstrate that neutrophils can migrate in a retrograde direction across endothelial cells and suggest that a population of tissue-experienced neutrophils with a distinct phenotype and function are present in the peripheral circulation in humans in vivo.