Biomedical subjects

J Koglin

Publications and source records attributed to J Koglin.

12 recordsLinked to original sources

PubMed1999

Alloimmune-mediated apoptosis: comparison in mouse models of acute and chronic cardiac rejection.

BACKGROUND: The purpose of the present study was (1) to compare apoptotic activity in models of acute and chronic rejection and (2) to study the cellular distribution of parenchymal versus inflammatory cell apoptosis. METHODS: Heterotopic cardiac mouse transplantation (CBA into C57BL/6) was used to produce allografts undergoing acute (day 7, untreated recipients, n=6) or chronic (day 55, anti-CD4/8 for 28 days, n=6) rejection. As references, we used 55-day isograft controls (n=5) and native hearts (n=6). To assess apoptotic activity, we quantified DNA laddering (32P incorporation), DNA fragmentation (antinucleosome ELISA), and caspase-1 transcript levels (32P-reverse transcriptase-polymerase chain reaction). To localize apoptosis, we performed terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. RESULTS: DNA laddering and nucleosome levels were increased in allografts undergoing acute or chronic rejection when compared with both controls. Both parameters were twofold higher in acutely compared with chronically rejecting hearts. Caspase-1 transcript levels were increased in acutely (P<0.0001) and chronically rejecting hearts (P=0.004). Acutely rejecting grafts had more terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive nuclei (53+/-3 nuclei/high-powered field) than chronically rejecting grafts (9+/-1 nuclei/high-powered field, P<0.0001), but the distribution between graft-infiltrating inflammatory cells and myocytes was similar. Vascular cells undergoing apoptosis were infrequent in both forms. CONCLUSION: Using four separate indices, apoptotic activity is more pronounced in cardiac allografts undergoing acute compared with chronic rejection. This reflects, in part, the degree of alloimmune response. However, we speculate that the contributions of apoptosis to various forms of rejection are multifactorial. The long-term outcome to the graft may depend upon the magnitude, timing, and target of programmed cell death.

Acute Disease↗

PubMed1999

Attenuated acute cardiac rejection in NOS2 -/- recipients correlates with reduced apoptosis.

BACKGROUND: The mechanisms through which NOS2-mediated pathways regulate graft failure in acute cardiac rejection are ill defined. To determine whether apoptosis promoted by NOS2 may contribute, we used a heterotopic transplant model to study mouse cardiac allografts placed in recipients with targeted gene deletion of NOS2. METHODS AND RESULTS: Using 5 different indexes of apoptosis, we showed that mouse cardiac allografts placed in NOS2 -/- recipients (n=7) had reduced apoptotic activity compared with those in NOS2 +/+ controls (n=8). There were significantly fewer TUNEL-positive nuclei per high-powered field (P<0.01), less DNA fragmentation (antinucleosome ELISA; P<0.05), lower corrected transcript levels for caspase-1 and -3 (32P reverse transcriptase-polymerase chain reaction; P<0.01), and reduced caspase-3 activity (cleavage of DEVD-pNA [P<0.001] and poly [ADP-ribose] polymerase) in grafts from NOS2 -/- recipients. This concordant reduction in apoptotic indexes paralleled the improved histological outcome of grafts transplanted into NOS2 -/- recipients (assessed as rejection scores; P=0.012). To identify pathways controlled by NOS2, we compared intragraft transcript levels of potential triggers and regulators. Whereas Fas ligand/Fas and tumor necrosis factor (TNF)-alpha/TNF receptor-1 levels were not altered by NOS2 deficiency, transcript levels for p53 were significantly lower in grafts from NOS2 -/- recipients, coinciding with a significant increase in the antiapoptotic Bcl-2/Bax balance and decrease in Bcl-Xl levels. CONCLUSIONS: Using NOS2 knockout mice, we demonstrated that NOS2-mediated pathways can promote acute rejection, at least in part, by inducing apoptotic cell death. When NOS2 is present, p53 might control NOS2-mediated apoptosis by stimulating Bax and repressing Bcl-2 and Bcl-Xl expression, which may activate the cell death program in the rejecting heart.

Animals↗

PubMed1998

Immune sources of transforming growth factor-beta1 reduce transplant arteriosclerosis: insight derived from a knockout mouse model.

Activated CD4-positive T cells are essential in the early stages of arteriosclerotic lesion development after cardiac transplantation. Besides its parenchymal effects, transforming growth factor-beta1 (TGF-beta1) mediates immunosuppressive effects on proliferation and activation of CD4 cells. This study was designed to assess immune contributions of TGF-beta1 to arteriosclerosis by comparing the effect of TGF-beta1-deficient and -competent infiltrating inflammatory cells on the development of intimal thickening in a heterotopic mouse transplant model (CBA to C57B6). Transplant arteriosclerosis was evaluated in cardiac grafts placed into knockout recipients heterozygous for TGF-beta1 (n=7) and was compared with those placed into wild-type recipients (n=11). At 55 days, allografts in TGF-beta1-deficient recipients had increased concentric intimal thickening. Computer-assisted analysis of all elastin-positive vessels (n=173) showed significantly increased luminal occlusion (67.8+/-5.6%) in grafts from TGF-beta1-deficient recipients compared with wild-type recipients (47.4+/-4.1%, P=0.003). To determine whether TGF-beta1 deficiency altered CD4 activation patterns, we studied intragraft cytokine expression. Using 32P-reverse-transcriptase polymerase chain reaction assays, we show that TGF-beta1-deficient recipients had an increased expression of the transcription factor STAT 4, interferon gamma, and interleukin-2 (Th1-type response) and unaltered or reduced expression of the transcription factor STAT 6, interleukin-4, and interleukin-10 (Th2-type response). Hence, when present, immune sources of TGF-beta1 attenuate transplant arteriosclerosis. This effect is associated with attenuation of Th1 forces.

Animals↗

PubMed1998

Exacerbated transplant arteriosclerosis in inducible nitric oxide-deficient mice.

BACKGROUND: Inducible NO synthase (NOS2, or iNOS) is upregulated in grafts with transplant arteriosclerosis. However, the functional role of NOS2 in the pathogenesis of transplant arteriosclerosis remains unclear. NOS2 may regulate lesion development by modulating the early alloimmune response and/or late myointimal thickening. METHODS AND RESULTS: To determine whether NOS2-mediated pathways protect against or promote transplant arteriosclerosis, we used NOS2-deficient mice as recipients in our vascularized chronic cardiac rejection model. The severity of vascular thickening in 55-day grafts placed into NOS2 -/- recipients (n=13) was compared with that in wild-type recipients (n=15). Computer-assisted analysis of all elastin-stained vessels (n=283) showed significantly increased luminal occlusion (77.11+/-9.4% versus 40.8+/-13.6%, P<.0001) and intima/media ratios in allografts from NOS2 -/- recipients (1.9+/-1.3 versus 0.4+/-0.3, P=.0002). To elucidate potential mechanisms, we studied NOS2 effects on T-cell differentiation (Th1/Th2) and neointimal smooth muscle cell accumulation. Normalized mRNA levels for Th1- (signal transducer and activator of transcription [STAT] 4, interleukin [IL]-2, interferon-gamma) and Th2- (STAT 6, IL-4, and IL-5) associated factors were comparable in both groups. In contrast, quantitative analysis of the alpha-actin-positive area showed a significant increase in the contribution of smooth muscle cells within the neointima in allografts from NOS2 -/- recipients (28.2+/-2.0%) compared with wild-type controls (13.2+/-2.3%; P<.0001). CONCLUSIONS: NOS2 plays a protective role in the development of transplant arteriosclerosis, suppressing neointimal smooth muscle cell accumulation.

Animals↗

PubMed1998

NOS2 mediates opposing effects in models of acute and chronic cardiac rejection: insights from NOS2-knockout mice.

To compare regulatory effects of NOS2 in acute and chronic cardiac allograft rejection, we used NOS2 knockout mice as recipients in a cardiac transplant model. To study acute and chronic rejection separately but within the same genetic strain combination, we compared allografts placed into recipients without or with immunosuppression (anti-CD4/8 for 28 days). NOS2 mRNA and protein expression were compared using 32P-RT-PCR and immunohistochemistry. In our acute rejection model, NOS2 was predominately localized to graft-infiltrating immune cells. At day 7, grafts in NOS2-deficient recipients (n = 7) showed reduced inflammatory infiltrates and myocyte damage resulting in significantly lower rejection scores (1.6 +/- 0.4) compared to wild-type controls (n = 18; 2.8 +/- 0.2, P = 0.002). In contrast, in our chronic rejection model, additional NOS2 expression was localized to graft-parenchymal cells. At day 55, grafts in NOS2-deficient recipients (n = 12) showed more parenchymal infiltration and parenchymal destruction (rejection score 3.8 +/- 0.1) than wild-type controls (n = 15; 1.6 +/- 0.2, P < 0.0001). This was associated with a significant decrease in ventricular contractility (palpation score 0.3 +/- 0.1 compared to 2.3 +/- 0.3 in wild-type, P < 0.0001). Hence, NOS2 promotes acute but prevents chronic rejection. These opposing effects during acute and chronic cardiac allograft rejection are dependent on the temporal and spatial expression pattern of NOS2 during both forms of rejection.

Acute Disease↗

PubMed1998

Reduced transplant arteriosclerosis in murine cardiac allografts placed in interferon-gamma knockout recipients.

To investigate the functional role of interferon (IFN)-gamma in transplant arteriosclerosis, BALB/c hearts were transplanted in immunosuppressed C57BL/6J recipients with (n = 10) or without (n = 10) targeted IFN-gamma gene deletion. In 55-day heart allografts, IFN-gamma deficiency resulted in a significant decrease in vascular thickening. The severity of intimal thickening measured as the percentage of luminal occlusion (mean +/- SEM) in all elastin stained vessels (n = 410) decreased from 37+/-5% in wild-type recipients to 18+/-5% in IFN-gamma -/- recipients (P < 0.005). In the few diseased vessels in grafts from IFN-gamma -/- recipients, the neointima was more cellular with a 90% increase in the nuclear density. This finding correlated with a 50% reduction in fibrosis estimated by alpha-smooth muscle actin cell accumulation in the neointima. The reduction in severity and altered composition of vascular thickening in grafts from IFN-gamma -/- recipients shows that IFN-gamma contributes to arteriosclerotic development following transplantation.

Animals↗

PubMed1997

[Heart transplantation--state of the art today].

In spite of pharmacological progress, end stage congestive heart failure is still associated with a decrease in quality and expectation of life. Heart transplantation remains the last therapeutic option for these patients. While the one year survival rate has increased over the last few years up to 84%, a major problem remains the significant lack of donors. Therefore, the criteria for the selection of candidates for cardiac transplantation have to be kept quite tight: Evidence of poor outcome without transplantation is associated with ejection fractions below 20 to 25%, cardiac indices less than 2.01/min/m2, left ventricular filling pressure above 20 mm Hg and a enddiastolic diameter of > 80 mm. There are, however, also quite important functional parameters indicating the need for heart transplantation, e.g. the maximal oxygene uptake being less than 10 ml/kg/min or below 50% of the age-appropriate value. Elevated pulmonary vascular resistance above 4 to 5 Wood units without a significant decrease during application of prostaglandin derivatives or inhalation of NO represents a contraindication for orthotopic heart transplantation; alternatively, a heterotopic transplantation can be considered. Since there is a significant shortage of suitable donor organs, the donor criteria have been broadened, e. g. the accepted donor age was increased to 60 years. Based on these extended criteria, a careful donor evaluation including cardiac history, cardiac examination, ECG and echocardiogram has to be performed. Coronary angiography in older donors is suggested, but in many cases not possible due to circumstances. Further precondition for a good graft function is a sophisticated donor management until the time of explantation. Hypovolemia and hypocalemia, hypothermia, hypoxia and rapid lost of circulating triiodothyronine (T3) have to be detected and balanced. The cardioplegic solution used might not only have an impact on the immediate postoperative performance of the graft, but also on the long term outcome, particularly with regard to graft vessel disease. There are generally two types of solutions: Those with intracellular and those with extracellular electrolyte concentrations. In addition, the potassium concentration might be of some importance. Potassium seems to damage endothelial cells and trigger subsequent immunological reactions. Therefore, high potassium concentrations in the cardioplegic solution might correlate with the incidence of graft vessel disease during the long term follow-up. The surgical technique for orthotopic heart transplantation developed at the beginning of the sixties by Lower and Shumway has been used unchanged for the last 30 years. The only alteration recently introduced is the separate direct anastomosis of the pulmonary and systemic veins in order to improve the atrial function. Until recently the commonly employed immunosuppressive strategy after heart transplantation consisted of the standard drugs cyclosporin, azathioprin and prednisolon. Some transplant-units use additionally induction therapy with antibody preparations. Many centers, however, abolished this regimen due to significant short and long term side effects. Promising new, more specific antibodies (which are chimerized or humanised) could revive the induction concept. The most thoroughly tested novel immunosuppressive agent is tacrolimus (FK506). It has been demonstrated to be 10 to 100 times more potent than cyclosporin A in in vitro and in vivo models. It binds to a different binding protein (FK-binding-protein) than cyclosporin (cyclophilin), but has a similar mechanism of action inhibiting the expression of T-cell-activator genes for certain cytokines. First non-randomised studies after heart transplantation performed at the University of Pittsburgh revealed that significantly more tacrolimus than cyclosporin patients were free of rejection. In order to confirm these observations, we performed a prospective randomised controlled clin

Clinical Trials as Topic↗

PubMed1997

Isolated defect of adenosine-mediated coronary vasodilation: functional evidence for a new microangiopathic entity.

OBJECTIVES: The present study describes an isolated defect of the coronary vasodilation in response to adenosine in five patients examined for clinically suspected coronary microangiopathy. BACKGROUND: Coronary microangiopathies can be defined functionally as dysregulation of the microcirculatory vasomotion. METHODS: The five patients were compared with 24 control subjects. Coronary flow velocity was measured with an intracoronary Doppler guide wire (0.018 in. [0.046 cm], 12 MHz) at rest and during intracoronary administration of adenosine (80 micrograms/min and 160 micrograms/min over 3 min each), papaverine (10-mg bolus) and acetylcholine (30 micrograms/min over 5 min). Diameters of the epicardial coronary arteries were measured by quantitative coronary angiography. RESULTS: All subjects (patients and control) exhibited angiographically normal epicardial coronary arteries and normal and comparable endothelium-independent and -dependent vasomotion, as assessed with papaverine (mean [+/-SD]-relative coronary flow reserve 2.62 +/- 0.66 vs. 2.97 +/- 0.88, p = 0.32) and acetylcholine (volumetric coronary flow reserve 2.61 +/- 0.27 vs. 2.91 +/- 0.67, p = 0.58), respectively. Affected patients were identified by an isolated complete defect of the adenosine-mediated vasodilation compared with control subjects (relative coronary flow reserve in response to 80 micrograms/min of adenosine 1.08 +/- 0.17 vs. 2.45 +/- 0.74 [p < 0.001] and 160 micrograms/min of adenosine 1.03 +/- 0.15 vs. 2.89 +/- 0.65 [p < 0.001]). CONCLUSIONS: These findings are consistent with functional evidence for a new entity of a coronary microangiopathy affecting a subtype of the endothelium-independent vasomotion.

Acetylcholine↗

PubMed1997

Time-dependent decrease of presynaptic inotropic supersensitivity: physiological evidence of sympathetic reinnervation after heart transplantation.

BACKGROUND: Sympathetic cardiac denervation of the transplanted human heart causes a loss of the presynaptic neuronal uptake1-mechanism with consecutive supersensitivity to uptake1-dependent catecholamines. A return of neuronal function (reinnervation) should result in a decrease of supersensitivity to catecholamines subjected to this uptake system and thus may alter the inotropic regulation. METHODS: Inotropic dose-response curves were compared in 12 patients who were studied 3 to 15 months after transplantation (early) and 17 patients who were studied 23 to 156 months after transplantation (late) with isoproterenol (uptake1-independent) and epinephrine (uptake1-dependent). The inotropic response to increasing doses of isoproterenol (5 to 20 ng/kg per min) and epinephrine (10 to 40 ng/kg per min) was assessed with echocardiography as increase of the systolic pressure/dimension ratio (delta P/D) and of the rate-corrected velocity of circumferential fiber shortening (delta Vcfc). RESULTS: Inotropic dose/response curves to isoproterenol were identical in the early and late recipients (during 20 ng/kg per min. isoproterenol: delta P/D 2.07 +/- 1.36 vs 2.18 +/- 1.42 mm Hg/mm; delta Vcfc 1.55 +/- 0.33 vs 1.40 +/- 0.38 square root of min-1 x %/ms), indicating an unchanged inotropic effect mediated by the postsynaptic beta-receptor/effector system. However, the inotropic response to epinephrine in early recipients was significantly attenuated in the late recipients (during 40 ng/kg per min. epinephrine: delta P/D 3.35 +/- 2.06 vs 1.51 +/- 0.68 mm Hg/mm, p < 0.01; delta Vcfc 1.80 +/- 0.42 vs 1.05 +/- 0.35 square root of min-1 x %/ms, p < 0.001). CONCLUSIONS: These findings provide evidence for an at least partial restoration of the neuronal catecholamine uptake and are consistent with a time-dependent sympathetic reinnervation after heart transplantation. Restoration of neuronal uptake seems to be of functional importance, because it profoundly alters the inotropic effect of circulating endogenous catecholamines in long-term survivors after heart transplantation.

Adrenergic alpha-Agonists↗

PubMed1996

Supersensitivity mismatch of adenosine in the transplanted human heart: chrono- and dromotropy versus inotropy.

Supersensitive negative chronotropic and dromotropic effects have been described for adenosine after human heart transplantation. The present study investigated a potential antiadrenergic negative inotropic effect of adenosine in heart transplant recipients compared to normal subjects. Sinus cycle length, PR interval, blood pressure, and inotropic response in vivo were compared in seven orthotopic heart transplant recipients and seven healthy volunteers (controls). Fractional shortening, velocity of circumferential fiber shortening, and systolic pressure/dimension ratio were calculated using M-mode echocardiography. Baseline ventricular contractility was normal in both groups. Although adenosine induced a significant exaggeration of the negative chronotropic and dromotropic effect in the transplant group, the positive inotropic effect of 20 ng/kg x min isoproterenol (FS 53.2 +/- 8.8 vs 51.0 +/- 4.6%, P/D 5.8 +/- 1.9 vs 6.0 +/- 0.8 mm Hg/mm, Vcf 0.21 +/- 0.04 vs 0.20 +/- 0.02%/ms for heart recipients vs controls) was not reduced by the additional administration of 150 micrograms/kg adenosine (FS 52.2 +/- 8.6 vs 51.7 +/- 5.6%, P/D 5.5 +/- 1.5 vs 5.4 +/- 0.8 mm Hg/mm, Vcf 0.24 +/- 0.07 vs 0.21 +/- 0.02%/ms for transplant recipients vs controls). In contrast to a chronotropic and dromotropic supersensitivity, adenosine does not attenuate the catecholamine-induced increase in contractility in the human ventricle in vivo after heart transplantation.

Adenosine↗

PubMed1996

Parasympathetic denervation supersensitivity of the transplanted human ventricle in vivo.

Sympathetic inotropic supersensitivity after transplantation-associated denervation of the cardiac autonomic nervous system has been described in humans previously. Potential changes of the parasympathetic regulation of the human ventricular contractility have not been investigated yet. We studied the antiadrenergic, negative inotropic effect of carbachol (3.6 micrograms/kg) during continuous beta-adrenergic stimulation (with isoproterenol, 20 ng.kg-1.min-1) in seven heart transplant recipients and seven healthy controls. Changes in ventricular contractility were calculated as increase of the systolic pressure-to-dimension ratio (delta P/D) and the rate-corrected velocity of circumferential fiber shortening (delta Vcfc), using M-mode echocardiography. In the control group, the isoproterenol-induced increase in contractility was attenuated only insignificantly by carbachol [delta P/D from 1.53 +/- 0.53 to 0.81 +/- 0.55 mmHg/mm, delta Vcfc from 0.77 +/- 0.20 to 0.63 +/- 0.22% x square root of beats/min (bpm)/ms]. In contrast, the transplant group exhibited a significant reduction of the isoproterenol-induced increase in contractility [delta P/D from 1.27 +/- 0.71 to -0.81 +/- 0.51 mmHg/mm (P < 0.01), delta Vcfc from 1.04 +/- 0.84 to 0.04 +/- 0.43% x square root of bpm/ms (P < 0.01)]. These data are consistent with parasympathetic indirect negative inotropic supersensitivity of the transplanted human heart in vivo.

Adrenergic beta-Agonists↗

PubMed1994

Antiadrenergic effect of carbachol but not of adenosine on contractility in the intact human ventricle in vivo.

OBJECTIVES: The purpose of this study was to investigate the antiadrenergic effects of adenosine and carbachol on beta-adrenoceptor-stimulated human ventricular contractility in vivo. In addition, the antiadrenergic effects of adenosine and carbachol were compared in vitro. BACKGROUND: Adenosine is reported to exhibit an antiadrenergic negative inotropic response in the beta-adrenergic-stimulated ventricular myocardium in vitro. The effect of adenosine is similar to the antiadrenergic effect of m-cholinoceptor stimulation in vitro. METHODS: The inotropic response in vivo was assessed in seven healthy volunteers by M-mode echocardiography and simultaneous blood pressure monitoring. It was calculated as the increase in the rate-corrected velocity of circumferential fiber shortening and in the systolic pressure/dimension ratio. All volunteers received pretreatment with 450 mg of dipyridamole/day for 48 h. In addition, the effects of adenosine and carbachol in the presence of 0.03 mumol/liter of isoproterenol on cumulative concentration-response curves of isolated, electrically driven human ventricular muscle strips were compared in vitro (n = 13). RESULTS: The positive inotropic response to continuous infusion of 20 ng/kg per min of isoproterenol (increase of rate-corrected velocity of circumferential fiber shortening [10.2 +/- 2.1% x square root of beats/min per ms] and increase of systolic pressure/dimension ratio 1.09 +/- 0.3 mm Hg/mm) was significantly (p < 0.01) reduced by 3.6 micrograms/kg body weight of intravenous carbachol (4.2 +/- 1.2% x square root of beats/min per ms, 0.21 +/- 0.18 mm Hg/mm) but not by 50 micrograms/kg of intravenous adenosine (8.2 +/- 3.1% x square root of beats/min per ms, 1.35 +/- 0.42 mm Hg/mm), although adenosine induced a significant negative dromotropic effect. In vitro comparison of force of contraction with cumulative concentration-response curves in the presence of 0.03 mumol/liter of isoproterenol demonstrated an EC50 value (concentration producing half-maximal effect) for adenosine 466 times higher than that for carbachol (65.3 vs. 0.14 mumol/liter, p < 0.001). CONCLUSIONS: In contrast to carbachol, adenosine does not attenuate the catecholamine-induced increase in contractility in the human ventricle in vivo. These differences between the A1-adenosine receptor- and m-cholinoceptor-mediated effects could be due to fewer A1-adenosine receptors or a less efficient receptor-effector coupling, or both.

Adenosine↗