Early complement activation follows eversion carotid endarterectomy and correlates with the time of clamping of the carotid artery

Therapeutic Modulation of the Complement Cascade in Stroke

Stroke is a leading cause of death and disability worldwide and an increasing number of ischemic stroke patients are undergoing pharmacological and mechanical reperfusion. Both human and experimental models of reperfused ischemic stroke have implicated the complement cascade in secondary tissue injury. Most data point to the lectin and alternative pathways as key to activation, and C3a and C5a binding of their receptors as critical effectors of injury. During periods of thrombolysis use to treat stroke, acute experimental complement cascade blockade has been found to rescue tissue and improves functional outcome. Blockade of the complement cascade during the period of tissue reorganization, repair, and recovery is by contrast not helpful and in fact is likely to be deleterious with emerging data suggesting downstream upregulation of the cascade might even facilitate recovery. Successful clinical translation will require the right clinical setting and pharmacologic strategies that are capable of targeting the key effectors early while not inhibiting delayed repair. Early reports in a variety of disease states suggest that such pharmacologic strategies appear to have a favorable risk profile and offer substantial hope for patients.

Peripheral Blood Lymphocyte Subsets (CD4+, CD8+ T Cells, NK Cells) in Patients with Cardiovascular and Neurological Complications after Carotid Endarterectomy

Background: The aim of the study was to evaluate the differences in the circulating immune cells’ subgroups after the atherosclerotic plaque removal in patients presenting with postoperative complications as compared to the patients without complications after carotid endarterectomy (CEA). Methods: Patients with significant carotid atherosclerosis (n = 124, age range: 44 to 87 years) who underwent CEA were enrolled in a prospective study. The immunology study using flow cytometry was performed to determine the percentages of peripheral blood T cells (CD4⁺, CD8⁺, Treg—CD4⁺/CD25⁺) and NK (natural killer) cells before and after the procedure. The data were expressed as the percentage of total lymphocytes ± the standard error of mean. Results: The mean percentage of lymphocytes (61.54% ± 17.50% vs. 71.82% ± 9.68%, p = 0.030) and CD4 T lymphocytes (T helper, 38.13% ± 13.78% vs. 48.39% ± 10.24%, p = 0.027) was significantly lower six hours after CEA in patients with postoperative 30-day cardiovascular and neurological complications as compared to the group without complications. On the other hand the mean NK level in the group with complications was significantly higher (21.61% ± 9.00% vs. 15.80% ± 9.31%, p = 0.048). Conclusions: The results of this study suggest that after carotid endarterectomy the percentages of circulating immune cells subsets differ in patients with and without postoperative complications.

New possibilities in the endovascular treatment of supraaortic vessels

Cerebrovascular disease, including stroke, represents the third-leading cause of death in Hungary and a leading cause of disability among the elderly population. The majority of all strokes are ischemic, mostly secondary to thromboembolic disease of the supraaortic vessels. We investigated new therapeutic methods in the endovascular treatment of these diseases. Surgical revascularization of supraaortic trunk stenosis is associated with high morbidity and mortality rates. Balloon angioplasty has become an increasingly accepted treatment of stenoocclusive supraaortic arterial disease. Natural history data and treatment guidelines do not exist for innominate and proximal common carotid artery lesions. We have confirmed in a large series of innominate artery angioplasties that it is a safe and effective procedure with an excellent initial success rate, with a lower complication rate than the surgical option and with a similar long-term patency rate as for surgery.

In the largest published study on transfemoral angioplasty of ostial and proximal common carotid artery stenosis we have proved that endovascular treatment has high success rate with low stroke/death rate. Carotid stenting (CAS) is an evolving alternative to surgery in the treatment of patients with carotid stenosis. Stent selection is influenced by several factors, including the carotid anatomy and lesion characteristics. We examined the wall adaptability of a new closed-cell carotid stent (NexStent), which was designed for carotid bifurcation treatment. Data obtained from angiographic and computed tomographic images indicate that the stent provides adequate expansion and adaptation to the carotid bifurcation.

There are two types of restenosis after carotid artery interventions: the early restenosis develops mainly within the first 24 months after the revascularization procedure and its pathological background is myointimal hyperplasia; on the other hand late restenosis is rather due to progression of primary atherosclerosis and occurs more than 2 years after carotid endarterectomy (CEA). We compared the early restenosis rate in a consecutive series of CAS versus CEA patients at a single cardiovascular institution. The data suggest that the incidence of restenosis after stenting was less common than after surgery.

Our results may help vascular surgeons and interventional radiologists to consider risk versus benefit when deciding treatment options for supraaortic arterial stenosis.

Autotransfusion system or integrated automatic suction device in minimized extracorporeal circulation: influence on coagulation and inflammatory response

OBJECTIVE

To measure surrogate markers of coagulation activation as well as of the systemic inflammatory response in patients undergoing primary elective coronary artery bypass grafting (CABG) using either the so-called Smart suction device or a continuous autotransfusion system (C.A.T.S.®).

METHODS

Fifty-eight patients being operated with a miniaturized circuit (minimal extracorporeal circuit, MECC) were prospectively randomized to using a so-called Smart suction device or a routine continuous autotransfusion system (C.A.T.S.®) for collection of mediastinal shed blood. The coagulation response was measured by thrombin-antithrombin complex (TAT) and D-dimer. The inflammatory response was measured by Interleukin 6 (IL-6) and complement factor 3a (C3a) at three different time points, before surgery, 2h after surgery, as well as 18 h after surgery.

RESULTS

No serious adverse cardiovascular event was observed. Serum levels of TAT significantly differed between both groups 2h after surgery (Smart suction 16.12 ± 13.51 μg l⁻¹ vs C.A.T.S® 9.83 ± 7.81 μg l⁻¹, p = 0.040) and returned to baseline values after 18 h in both groups. Serum levels of D-dimer showed a corresponding pattern with a peak 2h after surgery (Smart suction 1115 ± 1231 ng ml⁻¹ vs C.A.T.S.® 507 ± 604 ng ml⁻¹, p = 0.025). IL-6 levels also significantly differed between both groups 2h after surgery (Smart suction 186 ± 306 pg ml⁻¹ vs C.A.T.S.® 82 ± 71 pg ml⁻¹, p = 0.072). No significant changes in serum levels of C3a over time could be observed.

CONCLUSIONS

Despite no differences in the clinical course of patients with either Smart suction or C.A.T.S.® being observed, surrogate markers of coagulation and inflammation seem to be less pronounced in patients where cardiotomy blood is not being directly reinfused. As such, C.A.T.S.® should be preferred in routine CABG, as long as no extensive volume substitution is anticipated.

[Restenosis following endovascular interventions: clinical and experimental studies]

Restenosis following endovascular interventions is the main limitation of their long-term success. The incidence of restenosis varies according to the method (stenting, endarterectomy) and the treated vascular region, but the pathomechanism and risk factors are similar. The current article reviews of the author's previous studies in this field. In clinical studies, we compared the restenosis rate after carotid artery stenting and carotid endarterectomy. We also analyzed the complement activation profile after these interventions. In another study, we investigated the role of two polymorphisms of the estrogen receptor alpha in the occurrence of carotid restenosis after either carotid artery stenting or carotid endarterectomy. In an animal model of carotid endarterectomy, we studied the role of the nitrite-oxide-cyclic guanosine monophosphate signaling and the effect of the phosphodiesterase-5 inhibitor therapy in neointimal hyperplasia. Our results suggest that higher incidence of restenosis following carotid endarterectomy can be correlated with the more highly expressed complement activation after this type of carotid intervention. Polymorphisms in the estrogen receptor alpha gene could contribute to the restenosis formation, especially in women. Neointimal hyperplasia can be attenuated by increased cyclic guanosine monophosphate signaling.

Selective phosphodiesterase-5 inhibition reduces neointimal hyperplasia in rat carotid arteries after surgical endarterectomy

OBJECTIVE

Long-term results of surgical vessel reconstruction are compromised by restenosis caused by neointimal hyperplasia. Recent studies suggest that reduced cyclic guanosine monophosphate signaling is associated with neointima formation. In a rat model of endarterectomy, we investigated the effect of pharmacologic inhibition of cyclic guanosine monophosphate degradation on neointima formation by using the selective phosphodiesterase-5 inhibitor vardenafil.

METHODS

Carotid endarterectomy was performed in male Sprague-Dawley rats by means of incision of the right common carotid artery with removal of intima. Four groups were studied: unoperated control rats (n = 4), sham-operated rats (n = 9), control rats with endarterectomy (n = 9), or endarterectomized rats treated with vardenafil (10 mg/kg/day) postoperatively (n = 9). After 3 weeks, vessel compartment areas were measured by means of conventional microscopy with hematoxylin and eosin staining. Immunohistochemical analysis was performed to confirm neointima formation and the local cyclic guanosine monophosphate content. Plasma levels of cyclic guanosine monophosphate were determined by means of enzyme immunoassay. Student's t test was used for statistical evaluation.

RESULTS

Immunohistochemical analysis demonstrated intensive staining for transforming growth factor beta1 and alpha-smooth muscle actin in the control neointima. Vardenafil significantly reduced the stenosis grade (24.64% +/- 7.46% vs 54.12% +/- 10.30% in the control group, P < .05) and expression of transforming growth factor beta1, as well as alpha-smooth muscle actin, in the neointima. The immunohistochemical score for cyclic guanosine monophosphate was higher in the treated neointima (4.80 +/- 0.76 vs 2.84 +/- 0.40 in the control group, P < .05), and increased plasma cyclic guanosine monophosphate levels were found by means of enzyme immunoassay as well (84.65 +/- 12.77 pmol/mL vs 43.50 +/- 3.30 pmol/mL in the control group, P < .05).

CONCLUSIONS

Treatment with vardenafil can be considered a new possibility to prevent neointimal hyperplasia after endarterectomy.

Pentraxins, humoral innate immunity and tissue injury

Tissue damage elicits an inflammatory response, which comprises the rapid synthesis of acute phase molecules. The early local response shapes the resolution of inflammation. Pentraxins are evolutionary conserved soluble pattern recognition receptors, produced in the liver (e.g. C-reactive protein) or at sites of inflammation (the long pentraxin PTX3). Pentraxins behave as flexible adaptors of innate cell functions, complement activation and clearance of cell and matrix debris, regulating tissue hyperplasia and scarring and limiting the risk of autoimmunity associated to unscheduled cell death in vivo.