Joachim Kamenz

Interleukin-1β stimulates acute phase response and C-reactive protein synthesis by inducing an NFκB- and C/EBPβ-dependent autocrine interleukin-6 loop

Cytokines interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) are involved in acute phase response (APR). C-reactive protein (CRP), the prototype acute phase protein, may represent an important component in the pathogenesis of arteriosclerosis and may also be a target for drug development. Inhibition of CRP synthesis is one potential strategy. Understanding CRP synthesis, however, is a prerequirement for the development of CRP-inhibitors. From studies in hepatoma cell lines, IL-1beta and IL-6 were considered as equal inductors of APR and CRP. We investigated IL-1beta- and IL-6-effects on primary human hepatocytes (PHH) and Hep3B-cells. Kupffer cell contamination in PHH preparations was <3%. In PHH, several APP like CRP, haptoglobin (HP), lipopolysaccharide-binding protein (LBP) or hepcidin (HAMP) were regulated similarly by IL-1beta and IL-6, though signal transduction pathways of these cytokines are different. In Hep3B-cells, APP were regulated exclusively by IL-6. IL-1beta induced IL-6-synthesis in PHH but not in Hep3B-cells. C/EBPbeta-overexpression in Hep3B-cells reconstituted IL-1beta-mediated IL-6/CRP inducibility. In PHH and in C/EBPbeta-overexpressing Hep3B-cells, neutralizing anti-IL-6-antibodies blocked IL-1beta-mediated APR. Inhibition of protein synthesis and NFkappaB-signalling blocked IL-1beta- but not IL-6-mediated CRP-expression in PHH, whereas Janus-Kinase-1-inhibition blocked IL-1beta- and IL-6-mediated APR. IL-1beta induces APR in PHH via an NFkappaB- and C/EBPbeta-dependent autocrine IL-6-loop. These findings partly reconcile the understanding of APR and may help to design a transcriptional suppressor of CRP for the treatment of cardiovascular disease.

Intracoronary β-irradiation with a rhenium-188-filled balloon catheter: a randomized trial in patients with de novo and restenotic lesions ☆

Background Restenosis requiring reintervention is the main limitation of coronary angioplasty. Intracoronary irradiation reduces neointimal proliferation. We studied the efficacy of a self‐centering liquid rhenium‐188‐filled balloon catheter for coronary &bgr;‐brachytherapy. Methods and Results After successful coronary angioplasty with or without stenting, 225 patients (71% de novo lesions) were randomly assigned to receive 22.5 Gy intravascular &bgr;‐irradiation in 0.5‐mm tissue depth (n=113) or to receive no additional intervention (n=112). Clinical and procedural data did not differ between the groups except a higher rate of stenting in the control group (63%) compared with the rhenium‐188 group (45%, P<0.02). After 6 months of follow‐up, late loss was significantly lower in the irradiated group compared with the control group, both of the target lesion (0.11±0.54 versus 0.69±0.81 mm, P<0.0001) and of the total segment (0.22±0.67 versus 0.70±0.82 mm, P<0.0001). This was also evident in the subgroup of patients with de novo lesions and independent from stenting. Binary restenosis rates were significantly lower at the target lesion (6.3% versus 27.5%, P<0.0001) and of the total segment (12.6% versus 28.6%, P<0.007) after rhenium‐188 brachytherapy compared with the control group. Target vessel revascularization rate was significantly lower in the rhenium‐188 (6.3%) compared with the control group (19.8%, P=0.006). Conclusions Intracoronary &bgr;‐brachytherapy with a rhenium‐188 liquid‐filled balloon is safe and efficiently reduces restenosis and revascularization rates after coronary angioplasty. (Circulation. 2003;107:3022‐3027.)

Incidence of intimal proliferation and apoptosis following balloon angioplasty in an atherosclerotic rabbit model

OBJECTIVE The aim of this study was to determine the occurrence of apoptosis in relation to the proliferative response in the intimal layer after experimental balloon angioplasty of a pre-existing plaque. METHODS After induction of an intimal plaque in the right carotid artery by electrical stimulation, 26 rabbits underwent balloon angioplasty. Twelve animals served as a control group without performance of angioplasty after plaque induction. To study the time course of intimal apoptosis and cell proliferation the vessels were excised on day 7, 14 and 28 after balloon angioplasty. For in situ detection of apoptosis, the TUNEL-technique (TdT-mediated d-UTP fluorescein nick end labeling) was used. In addition, bromodeoxyuridine labeling in all animals allowed the determination of the percentage of cells undergoing DNA synthesis in the neointimal area. Additionally, smooth muscle cells were detected by immunostaining of alpha-actin and macrophages by a specific antibody (RAM 11). RESULTS Within 28 days of balloon angioplasty, the number of cells undergoing apoptosis remained at a very low level and was not significantly different to the control group without interventional treatment (controls: 0.1 +/- 0.15%; 7 days: 0.44 +/- 0.68%; 14 days: 0.13 +/- 0.11%; 28 days: 0.1 +/- 0.1%). In contrast, the number of cells undergoing DNA synthesis was significantly increased at day 7 after angioplasty (3.72 +/- 2.0% vs. 0.51 +/- 0.29% in controls), resulting in an increase of the total intimal area from 0.088 +/- 0.037 mm2 in the control animals up to 0.256 +/- 0.172 mm2 at day 28 following balloon dilatation. CONCLUSIONS Our data showed that significant changes in the occurrence of apoptosis are not involved in the regulation of cellular turnover during the examined time period after vessel wall injury. The lacking up-regulation of apoptosis in comparison to the increased cell proliferation in order to maintain the tissue balance is perhaps an important regulatory mechanism leading to intimal hyperplasia after vascular injury in this animal model. Overall, we suggest that there may be a delicate balance between cell proliferation and apoptosis in smooth muscle cells of the vessel wall, and only small shifts in this balance could account for both cellular accumulation in restenotic lesions as well as cell death in mature atheroma.

Local excitation black blood imaging at 3T: application to the carotid artery wall.

A novel approach for imaging large sections of the carotid artery wall at isotropic spatial resolution is presented. Local excitation by means of 2D excitation pulses was combined with a diffusion‐prepared segmented steady‐state black‐blood gradient echo technique enabling the assessment of the carotid arterial wall over a range of up to 15 cm. The carotid arteries of five healthy volunteers were imaged with the proposed technique. Signal‐to‐noise ratio (SNR), wall‐lumen contrast‐to‐noise ratio (CNR), and vessel dimensions were assessed and compared to conventional excitation techniques. In all experiments black‐blood contrast could be realized over the covered carotid arteries with similar SNR and CNR as the conventional technique covering the region of the bulbus only. The proposed technique enables the time‐efficient coverage of the carotid arteries without compromising wall‐lumen CNR and geometrical accuracy. Furthermore, the proposed technique appears to be less sensitive to motion and swallowing artifacts due to the local character of the excitation. Magn Reson Med, 2008.

Endovascular irradiation with the liquid β-emitter Rhenium-188 to reduce restenosis after experimental wall injury

OBJECTIVE Postinterventional irradiation is a new therapeutic concept in the prevention of restenosis. The liquid beta-emitter Rhenium-188 allows endovascular brachytherapy using a conventional balloon catheter without the problem of centering the radiation source. In an animal model of restenosis the feasibility and the dose dependent effect of intravascular brachytherapy with a Rhenium-188 filled balloon catheter was investigated. METHODS In 68 male New Zealand White rabbits after endothelial denudation of the right common carotid artery with a Fogarty catheter, endovascular irradiation was performed with a Rhenium-188 filled 3.0-mm balloon catheter using different dosages (0, 7.5, 15, 30, 45 and 60 Gy at the surface of the vessel). Then 4 weeks after the intervention the vessels were excised and histologically analyzed. RESULTS Whereas at 7.5 Gy the intimal area (median [first quartile; third quartile]) did not differ significantly from the control (0.46 mm(2) [0.33 mm(2), 0.75 mm(2)] vs. 0.49 mm(2) [0.34 mm(2), 0.66 mm(2)]), neointimal hyperplasia was decreased significantly at 15 Gy (0.15 mm(2) [0.04 mm(2), 0.17 mm(2)]) and 30 Gy (0.07 mm(2) [0.04 mm(2), 0. 10 mm(2)]), and completely inhibited at the highest dosages (45 Gy: 0 mm(2) [0 mm(2), 0.04 mm(2)]; 60 Gy: 0 mm(2) [0 mm(2), 0.01 mm(2)]). CONCLUSIONS Catheter transmitted endovascular irradiation with the liquid beta-emitter Rhenium-188 after vascular injury is feasible and effectively reduced neointimal hyperplasia in hypercholesterolemic rabbits. A significant reduction of the neointimal formation could be found already at a radiation absorbed dose of 15 Gy at the vessel surface. Following a surface dosage of 45 Gy the proliferative response to the vessel injury is almost completely abolished.

Septic shock caused by Streptococcus pneumoniae in a post-splenectomy patient successfully treated with recombinant human activated protein C.

We present a case of severe sepsis due to Streptococcus pneumoniae, serotype 22F treated with recombinant human activated protein C (drotrecogin alpha activated) (DrotAA). APACHE II score at admission was 34 with a predicted mortality of 81%. A wide range of cytokines, chemokines and receptors was measured before and after DrotAA treatment. Soon after infusion of 24 µg DrotAA per kg bodyweight and h (µg/kg/h) over a period of 96 h, cytokine levels fell markedly. The patient survived and was discharged after 6 weeks of hospitalization. In conclusion, administration of DrotAA in a case of Streptococcus pneumoniae-induced septic shock was followed by dramatic changes in serum levels of immuno-regulatory cytokines.

Local intra-arterial drug delivery for prevention of restenosis: comparison of the efficiency of delivery of different radiopharmaceuticals through a porous catheter.

Tepe G, Duda SH, Kalinowski M, et al. Local intra-arterial drug delivery for prevention of restenosis: Comparison of the efficiency of delivery of different radiopharmaceuticals through a porous catheter. Invest Radiol 2001;36:245–249. rationale and objectives. Several radiopharmaceuticals were administered through a porous balloon catheter to compare the absolute amount deposited and the retention in the vessel wall. The reported efficiency of local drug delivery ranges from 0.001% to 0.1%, with poor retention after 24 hours. methods.An endothelin derivative (n = 6), pertechnetate (n = 6), hexamethylpropylene amineoxime (HMPAO) (n = 5), ethyl cysteinate dimer (ECD) (n = 5), and tin colloid (n = 5) were labeled with 185 MBq/mL 99m-technetium. After balloon denudation of the infrarenal aorta in 27 New Zealand White rabbits, 100 &mgr;L of each agent was administered through a porous balloon at a pressure of 4 bar. Dynamic and static whole-body scintigrams were obtained for 24 hours. The infrarenal aorta was excised and the activity calculated in a gamma counter. results.Apart from their retention in the region of local administration, the radiopharmaceuticals showed different distribution patterns. The highest regional tracer retention was observed with HMPAO. After administration of HMPAO, a significant difference between regional (vessel wall plus surrounding tissue: 14.5% of injected dose [ID]/24 hours) and local (vessel wall: 1.8% ID/24 hours) delivery was found. In contrast, ECD was eliminated quickly (local retention after 24 hours = 0% ID). The retention efficiencies were HMPAO > endothelin derivative > tin colloid > pertechnetate > ECD. conclusions.The different physicochemical and pharmacokinetic properties of radiopharmaceuticals resulted in different delivery efficiencies after local application.

Sirolimus inhibits key events of restenosis in vitro/ex vivo: evaluation of the clinical relevance of the data by SI/MPL- and SI/DES-ratio's

BackgroundSirolimus (SRL, Rapamycin) has been used successfully to inhibit restenosis both in drug eluting stents (DES) and after systemic application. The current study reports on the effects of SRL in various human in vitro/ex vivo models and evaluates the theoretical clinical relevance of the data by SI/MPL- and SI/DES-ratios.MethodsDefinition of the SI/MPL-ratio: relation between significant inhibitory effects in vitro/ex vivo and the maximal plasma level after systemic administration in vivo (6.4 ng/ml for SRL). Definition of the SI/DES-ratio: relation between significant inhibitory effects in vitro/ex vivo and the drug concentration in DES (7.5 mg/ml in the ISAR drug-eluting stent platform). Part I of the study investigated in cytoflow studies the effect of SRL (0.01–1000 ng/ml) on TNF-α induced expression of intercellular adhesion molecule 1 (ICAM-1) in human coronary endothelial cells (HCAEC) and human coronary smooth muscle cells (HCMSMC). Part II of the study analysed the effect of SRL (0.01–1000 ng/ml) on cell migration of HCMSMC. In part III, IV, and V of the study ex vivo angioplasty (9 bar) was carried out in a human organ culture model (HOC-model). SRL (50 ng/ml) was added for a period of 21 days, after 21 and 56 days cell proliferation, apoptosis, and neointimal hyperplasia was studied.ResultsExpression of ICAM-1 was significantly inhibited both in HCAEC (SRL ≥ 0.01 ng/ml) and HCMSMC (SRL ≥ 10 ng/ml). SRL in concentrations ≥ 0.1 ng/ml significantly inhibited migration of HCMSMC. Cell proliferation and neointimal hyperplasia was inhibited at day 21 and day 56, significance (p < 0.01) was achieved for the inhibitory effect on cell proliferation in the media at day 21. The number of apoptotic cells was always below 1%.ConclusionSI/MPL-ratios ≤ 1 (ICAM-1 expression, cell migration) characterize inhibitory effects of SRL that can be theoretically expected both after systemic and local high dose administration, a SI/MPL-ratio of 7.81 (cell proliferation) represents an effect that was achieved with drug concentrations 7.81-times the MPL. SI/DES-ratios between 10-6 and 10-8 indicate that the described inhibitory effects of SRL have been detected with micro to nano parts of the SRL concentration in the ISAR drug-eluting stent platform. Drug concentrations in DES will be a central issue in the future.

EFFECT OF THE ANTIOXIDANT NICANARTINE ON THE PROLIFERATIVE AND INFLAMMATORY RESPONSE AFTER EXPERIMENTAL BALLOON ANGIOPLASTY

BackgroundAntioxidant treatment seems to reduce the development of restenosis after percutaneous transluminal angioplasty. In this study, the effect of Nicanartine, a new antioxidant drug with both antiproliferative and lipid-lowering properties, on the proliferative and inflammatory response after balloon angioplasty was investigated in a rabbit model of restenosis. MethodsTo induce pre-interventional plaques in the common carotid artery of 48 New Zealand White rabbits, electrostimulation was carried out for 28 days. After a break of 7 days, balloon angioplasty was performed in 36 animals, of which 18 received Nicanartine at a dose of 120 mg/kg body weight; the other 18 served as a control group. The vessels were excised by day 7 and 28 after balloon angioplasty and examined for intimal plaque size, macrophage content and proliferative activity. Bromodeoxyuridine labeling was used to determine proliferating cells in the dilated segment; macrophages were detected using the RAM-11 antibody. ResultsIn the Nicanartine-treated group, immunohistological quantification 7 days after intervention showed a statistically significant (P < 0.05) reduction of both cells undergoing DNA synthesis (1.6 ± 1.4% versus 3.7 ± 2.2%) and intimal macrophages (0.7 ± 1.2% versus 1.3 ± 0.6%). Twenty-eight days after balloon angioplasty, proliferative activity in both groups was decreased to a level comparable to the non-dilated control groups. A clear trend towards smaller plaques could be seen in the Nicanartine group (0.146 ± 0.077 mm2 versus 0.255 ± 0.174 mm2). Total cholesterol levels did not differ significantly between the groups. ConclusionUnder treatment with Nicanartine a clear reduction in the proliferative and inflammatory response after balloon angioplasty was observed. Antioxidant treatment, especially with compounds having antiproliferative and lipid-lowering properties, appears to be an effective secondary preventive strategy after interventional treatment in patients with coronary artery disease.