Increased arterial stiffness in cyclosporine-treated lung transplant recipients early after transplantation

Impact of immunosuppressive therapy on arterial stiffness in kidney transplantation: are all treatments the same?

Arterial stiffness is a biologic process related to ageing and its relationship with cardiovascular risk is well established. Several methods are currently available for non-invasive measurement of arterial stiffness that provide valuable information to further assess patients’ vascular status in real time. In kidney transplantation recipients, several factors could accelerate the stiffness process, such as the use of calcineurin inhibitors (CNIs), the presence of chronic kidney disease and other classical cardiovascular factors, which would explain, at least in part, the high cardiovascular mortality and morbidity. Despite the importance of arterial stiffness as a biomarker of cardiovascular risk, and unlike other cardiovascular risk factors (e.g. left ventricular hypertrophy), only a few clinical trials or retrospective studies of kidney recipients have evaluated its impact. In this review we describe the clinical impact of arterial stiffness as a prognostic marker of cardiovascular disease and the effects of different immunosuppressive regimens on its progression, focusing on the potential benefits of CNI-sparing protocols and supporting the rationale for individualization of immunosuppression in patients with lower arterial elasticity. Among the immunosuppressive drugs, a belatacept-based regimen seems to offer better vascular protection compared with CNIs, although further studies are needed to confirm the preliminary positive results.

Vascular resistance and endothelial function in cyclosporine-treated lung transplant recipients

The majority of patients undergoing solid organ transplantation develop hypertension, to which vasoconstriction and impaired endothelial function have been suggested to contribute. We compared basal vascular resistance and nitric oxide-mediated endothelial-dependent and independent vasoreactivity between cyclosporine-treated lung transplant recipients and healthy subjects. Forearm blood flow was measured by venous occlusion plethysmography at rest and during acetylcholine, glyceryltrinitrate and N(G)-monomethyl-L-arginine acetate (L-NMMA) infusion in 11 lung transplant recipients 3-5 years after transplantation and in eight healthy subjects. Forearm vascular resistance (FVR) was calculated. Plasma levels of endothelin-1 (ET-1) and von Willebrand factor (vWf) were analysed. Basal vascular resistance was 40% lower in transplant recipients than in healthy subjects (P = 0.021). Endothelial-dependent and independent vasodilation did not differ. Plasma levels of ET-1 and vWf were higher in transplant recipients (P = 0.009 and P < 0.001 respectively). There was a significant correlation between ET-1 levels and FVR in healthy subjects (r = 0.83, P = 0.042), but not in transplant recipients (r = -0.14, P = 0.70). The findings oppose the theory of generalized vasoconstriction and impaired endothelial function in the pathogenesis of hypertension after transplantation. Increased plasma levels of ET-1 do not cause increased FVR in lung transplant recipients.

New-Onset Cardiovascular Risk Factors in Lung Transplant Recipients

BACKGROUND

Cardiovascular disease (CVD) is a common cause of morbidity and mortality after solid-organ transplantation. Both pre-existing cardiovascular risk factors in recipients and immunosuppressive drug toxicity may contribute to CVD. We sought to describe the prevalence of new-onset hypertension, hypercholesterolemia and diabetes mellitus in lung transplant recipients and to identify predisposing factors.

METHODS

One hundred twenty-six patients without pre-transplant hypertension, hypercholesterolemia or diabetes were included in a retrospective descriptive study. All patients were initially on cyclosporine-based triple immunosuppression. Cumulative prevalence of new-onset hypertension, hypercholesterolemia and diabetes were calculated. A multivariate Cox regression model was used to identify independent pre-operative predictors.

RESULTS

By 3 years after transplantation, 90% of patients had developed at least 1 cardiovascular risk factor and 40% developed > or = 2 risk factors. The cumulative prevalence of new-onset hypertension at 1, 3, 5 and 7 years was 45%, 65%, 67% and 72%, respectively. The corresponding prevalence for hypercholesterolemia was 16%, 33%, 48% and 58%, and for diabetes 6%, 7%, 7% and 10%, respectively. The independent pre-transplant predictors were: for hypertension, diastolic blood pressure (odds ratio: 2.1 per 10 mm Hg [95% confidence interval: 1.3 to 3.5], p = 0.005); for hypercholesterolemia, serum cholesterol level (OR: 1.8 per mmol/liter [95% CI: 1.3 to 2.5], p < 0.001); and, for diabetes, cystic fibrosis diagnosis (OR: 7.4 [95% CI: 1.6 to 35.6], p = 0.01) and blood glucose level (OR 2.2 per mmol/liter [95% CI 1.1 to 4.5], p = 0.02).

CONCLUSIONS

The majority of cyclosporine-treated lung transplant recipients develop new-onset hypertension or hypercholesterolemia early after transplantation. Pre-transplant blood pressure, serum cholesterol levels and blood glucose levels are independent predictors of post-transplant hypertension, hypercholesterolemia and diabetes, respectively.

Blunted Vascular Response to Endothelin-A Receptor Blockade in Cyclosporine-Treated Lung Transplant Recipients

BACKGROUND

The majority of cyclosporine-treated transplant recipients develop hypertension. Endothelin-1 (ET-1) has been suggested to mediate cyclosporine-induced vasoconstriction when binding to ET-A receptors. We hypothesized that cyclosporine-treated lung transplant recipients have an increased basal vascular resistance and an augmented response to ET-A receptor blockade.

METHODS

The selective ET-A receptor blocker BQ-123 (10 and 50 nmol/min) was infused into the brachial artery, alone or in combination with the nitric oxide synthase inhibitor NG-monomethyl-L-arginine acetate (L-NMMA) (2 and 4 micromol/min) in 10 lung transplant recipients without pharmacologically treated hypertension and 8 healthy controls. Forearm blood flow (FBF) was measured by venous occlusion plethysmography and plasma levels of ET-1 were analyzed.

RESULTS

Baseline forearm vascular resistance did not differ between recipients and controls (32 +/- 4 vs 42 +/- 7 mmHg/ml/min, p = 0.32). BQ-123 increased FBF in controls but not in recipients (26% +/- 9% vs 5% +/- 11% at 10 nmol/min, p = 0.043 between groups). Coinfusion of BQ-123 and L-NMMA caused a comparable decrease in FBF in recipients and controls (-26% +/- 11%, vs -34% +/- 7%). Baseline ET-1 was higher in recipients (17.2 +/- 1.1 vs 14.7 +/- 0.8 pg/ml, p = 0.038). BQ-123 infusion increased plasma ET-1 in controls but not in recipients (+24% +/- 11% vs -0.4% +/- 6.2%, p = 0.029 between groups).

CONCLUSIONS

The results demonstrate that cyclosporine-treated lung transplant recipients have increased plasma levels of ET-1 and a blunted response to ET-A receptor blockade compared with healthy subjects. In contrast, we found no evidence for an increased basal vascular resistance in transplant recipients. These alterations in endothelin handling may contribute to the development of transplant-associated hypertension.