Association of a change in immunosuppressive regimen with hemodynamic and inflammatory markers of cardiovascular disease after kidney transplantation

Tacrolimus monitoring in hair samples of kidney transplant recipients

Background

Calcineurin inhibitors, including tacrolimus, remain a cornerstone of immunosuppressive therapy after kidney transplantation. However, the therapeutic window is narrow, and nephrotoxic side effects occur with overdose, while the risk of alloimmunization and graft rejection increases with underdose. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) allows quantification of tacrolimus in biological samples from patients. This study investigates the feasibility of quantifying tacrolimus in scalp hair from kidney transplant (KT) recipients and correlates hair tacrolimus concentrations with tacrolimus dosage and blood trough levels. The aim was to provide proof-of-principle for hair tacrolimus drug monitoring in KT recipients.

Method

Single-center prospective study between September 9, 2021 and December 4, 2021, including KT recipients under tacrolimus. Minors, patients with active skin or hair diseases, and patients with scalp hair shorter than 4 cm were excluded from participation. Scalp hair was collected from the posterior vertex of patients, cut into segments, and analyzed for tacrolimus by LC-MS/MS. Patients filled out a questionnaire on hair treatments and washing habits. In parallel, tacrolimus trough levels were measured in whole blood and correlated with hair tacrolimus concentrations.

Results

In total, 39 consenting KT recipients were included, and hair samples were collected at 53 visits. Tacrolimus was detected in 98% of hair samples from patients exposed to the drug. Tacrolimus hair levels and whole blood trough levels were correlated with a beta coefficient of 0.42 (95% CI: -0.22-1.1, p = n.s.). Age and dark hair affected hair tacrolimus measurements, while different tacrolimus formulations (immediate release vs. extended release), hair washes, and permanent coloring did not. Longitudinal measurements in a subgroup of patients indicate that long-term measurement of hair tacrolimus levels is feasible.

Conclusion

Measuring tacrolimus in hair is a potentially reliable method to monitor drug exposure in KT patients. Rapid wash-in effects and consistent concentrations over time indicate that tacrolimus is incorporated into the hair matrix, allowing temporal resolution in the analysis of recent exposure and exposure history. This method provides a simple and low-risk alternative to regular blood sampling, sparing patients from frequent hospital visits through the self-collection of hair samples.

Cardiovascular protection associated with cilostazol, colchicine and target of rapamycin inhibitors

ABSTRACT

An alteration in extracellular matrix production by vascular smooth muscle cells is a crucial event in the pathogenesis of vascular diseases such as aging-related, atherosclerosis and allograft vasculopathy. The human target of rapamycin (TOR) is involved in the synthesis of extracellular matrix by vascular smooth muscle cells. TOR inhibitors reduce arterial stiffness, blood pressure, and left ventricle hypertrophy and decrease cardiovascular risk in kidney graft recipients and patients with coronary artery disease and heart allograft vasculopathy. Other drugs that modulate extracellular matrix production such as cilostazol and colchicine have also demonstrated a beneficial cardiovascular effect. Clinical studies have consistently shown that cilostazol confers cardiovascular protection in peripheral vascular disease, coronary artery disease, and cerebrovascular disease. In patients with type 2 diabetes, cilostazol prevents the progression of subclinical coronary atherosclerosis. Colchicine reduces arterial stiffness in patients with Familial Mediterranean Fever and patients with coronary artery disease. Pathophysiological mechanisms underlying the cardioprotective effect of these drugs may be related to interactions between the cytoskeleton, TOR signaling and cyclic AMP synthesis that remain to be fully elucidated. Adult vascular smooth muscle cells exhibit a contractile phenotype and produce little extracellular matrix. Conditions that upregulate extracellular matrix synthesis induce a phenotypic switch toward a synthetic phenotype. TOR inhibition with rapamycin reduces extracellular matrix production by promoting the change to the contractile phenotype. Cilostazol increases the cytosolic level of cyclic AMP, which in turn leads to a reduction in extracellular matrix synthesis. Colchicine is a microtubule-destabilizing agent that may enhance the synthesis of cyclic AMP.

Early Switch From Tacrolimus to Everolimus After Liver Transplantation: Outcomes at 2 Years

The observational CERTITUDE study follows liver transplant patients who completed the SIMCER trial. SIMCER randomized patients at month 1 after transplant to everolimus (EVR) with stepwise tacrolimus (TAC) withdrawal or to standard TAC, both with basiliximab induction and mycophenolic acid ± steroids. After completing SIMCER at 6 months after transplant, 65 EVR-treated patients and 78 TAC-treated patients entered CERTITUDE. At month 24 after transplant, 34/65 (52.3%) EVR-treated patients remained calcineurin inhibitor (CNI) free. Mean estimated glomerular filtration rate (eGFR) was significantly higher with EVR versus TAC during months 3-12. At month 24, eGFR values were 83.6 versus 75.3 mL/minute/1.73 m² , respectively (P = 0.90) and adjusted mean change in eGFR from randomization was -8.0 versus -13.5 mL/minute/1.73 m² (P = 0.15). At month 24, 45.9%, 31.1%, and 23.0% of EVR-treated patients had chronic kidney disease stages 1, 2, and 3, respectively, versus 25.7%, 45.7%, and 28.6% of TAC-treated patients (P = 0.05). Treated biopsy-proven acute rejection affected 4 EVR-treated patients and 2 TAC patients during months 6-24. Adverse events led to study discontinuation in 15.4% and 7.7% of EVR-treated and TAC-treated patients, respectively. Grade 3 or 4 hematological events were rare in both groups. A CNI-free EVR-based maintenance regimen appears feasible in approximately half of liver transplant patients. It preserves renal function effectively with good efficacy without compromising safety or hematological tolerance.

Effect of Immunosuppressive Treatment on Carotid Atherosclerosis in Renal Transplant Recipients

BACKGROUND

The aim of this study was to compare the effect of immunosuppressive regimens using either mammalian target of rapamycin inhibitors (mTORi) or calcineurin inhibitors (CNI) on the risk of atherosclerosis in renal transplant patients.

MATERIALS AND METHODS

The study involved a group of 24 recipients treated with mTORi (mTORi group) and a group of 20 recipients treated with immunosuppressive regimen based on CNI (CNI group). Laboratory and clinical markers of cardiovascular risk in both groups were investigated. Carotid atherosclerosis was evaluated by measurement of the intima media thickness (IMT) of the common and internal carotid artery walls and detection of carotid plaques by a high-resolution ultrasonography. The study was performed 3-24 years after transplantation.

RESULTS

The mTORi group showed higher level of total cholesterol (242 vs 201 mg/dL; P < .004), low-density lipoprotein cholesterol (140 vs 116 mg/dL; P < .05), and triglycerides (226 vs 168 mg/dL; P < .01). Posttransplant diabetes developed in 34% of mTORi group compared with 25% in the CNI group. The mean of IMT (left and right) of common and internal carotid arteries was similar in both groups. Carotid plaques were detected in 46% of patients from the mTORi group and 25% from CNI group (P < .02). The presence of carotid plaques combined with an IMT of >0.9 mm were associated with male gender, mTORi treatment (P = .03), and cardiovascular events. The incidence of coronary heart disease was higher in mTORi group than in CNI group (53% vs 20%; P = .03).

CONCLUSIONS

There was not beneficial effect of immunosuppressive treatment with mTORi on carotid atherosclerosis in renal transplant patients.

Metabolic consequences of modern immunosuppressive agents in solid organ transplantation

Among other factors, sophistication of immunosuppressive (IS) regimen accounts for the remarkable success attained in the short- and medium-term solid organ transplant (SOT) survival. The use of steroids, mycophenolate mofetil and calcineurin inhibitors (CNI) have led to annual renal graft survival rates exceeding 90% in the last six decades. On the other hand, attrition rates of the allograft beyond the first year have remained unchanged. In addition, there is a persistent high cardiovascular (CV) mortality rate among transplant recipients with functioning grafts. These shortcomings are in part due to the metabolic effects of steroids, CNI and sirolimus (SRL), all of which are implicated in hypertension, new onset diabetes after transplant (NODAT), and dyslipidemia. In a bid to reduce the required amount of harmful maintenance agents, T-cell-depleting antibodies are increasingly used for induction therapy. The downsides to their use are greater incidence of opportunistic viral infections and malignancy. On the other hand, inadequate immunosuppression causes recurrent rejection episodes and therefore early-onset chronic allograft dysfunction. In addition to the adverse metabolic effects of the steroid rescue needed in these settings, the generated proinflammatory milieu may promote accelerated atherosclerotic disorders, thus setting up a vicious cycle. The recent availability of newer agent, belatacept holds a promise in reducing the incidence of metabolic disorders and hopefully its long-term CV consequences. Although therapeutic drug monitoring as applied to CNI may be helpful, pharmacodynamic tools are needed to promote a customized selection of IS agents that offer the most benefit to an individual without jeopardizing the allograft survival.

Hyperleptinemia Is a Risk Factor for the Development of Central Arterial Stiffness in Kidney Transplant Patients

BACKGROUND

Arterial stiffness could cause adverse outcomes in kidney transplant (KT) patients. Leptin has a role in influencing vascular smooth muscle that may contribute to atherosclerosis. The aim of this study was to evaluate the relationship between fasting serum leptin concentration and carotid-femoral pulse wave velocity (cfPWV) in KT patients.

MATERIALS AND METHODS

Fasting blood samples were obtained from 55 KT patients and 65 subjects from the outpatient department were enrolled as the control group. The cfPWV values of >10 m/s were used to define as the high arterial stiffness group and <10 m/s as the low arterial stiffness group. The predictive ability of leptin for arterial stiffness of KT was assessed using receiver operating characteristic (ROC) curve and multivariate logistic regression analyses.

RESULTS

Kidney transplant patients had lower hemoglobin, but higher blood urea nitrogen, creatinine, total cholesterol, diastolic blood pressure, intact parathyroid hormone levels, and leptin levels than controls. Although cfPWV levels were higher in KT patients, there is no difference of cfPWV levels between KT patients and control (P = .595). Fifteen KT patients (27.3%) were defined in the high arterial stiffness group, and serum leptin level was higher in the high arterial stiffness group compared with the low arterial stiffness group in KT patients (P < .001). Multivariate logistic regression analysis showed that leptin (odds ratio: 1.044, 95% confidence interval [CI]: 1.016-1.072, P = .002) was an independent predictor of arterial stiffness in KT patients. The sensitivity, specificity, positive predictive value, negative predictive value, and area under the ROC curve predicting arterial stiffness in KT patients were 73.33%, 87.5%, 68.7%, 89.7%, and 0.828 (95% CI: 0.703-0.917, P < .001), and the leptin cut-off value was 74.14 ng/mL.

CONCLUSION

Serum fasting leptin level could predict the development of central arterial stiffness of KT patients.

Serum leptin levels positively correlate with peripheral arterial stiffness in kidney transplantation patients

BACKGROUND

Leptin is a protein predominantly produced by adipocytes that plays a pathophysiologic role in the pathogenesis of hypertension and cardiovascular diseases. The aim of this study was to evaluate the relationship between fasting serum leptin levels and peripheral arterial stiffness among kidney transplant (KT) patients.

METHODS

Fasting blood samples were obtained from 74 KT patients. Brachial-ankle pulse wave velocity (baPWV) was measured in the right or left brachial artery to the ankle segments using an automatic pulse wave analyzer (VaSera VS-1000). Plasma leptin levels were measured using a commercial enzyme-linked immunosorbent assay kit. In this study, left or right baPWV values of less than 14.0 m/s were used to define the high arterial stiffness group.

RESULTS

Forty KT patients (54.1%) were defined in high arterial stiffness group. Hypertension (P < .010), diabetes (P < .010), age (P = .010), KT duration (P = .013), triglyceride levels (P = .016), systolic blood pressure (P < .001), waist circumference (P = .031), and leptin level (P < .001) were higher, whereas serum high-density lipoprotein cholesterol level (P = .030) was lower in the high arterial stiffness group compared with the low arterial stiffness group. Multivariate logistic regression analysis showed that leptin (odds ratio, 1.033; 95% CI, 1.004-1.062; P = .023), KT duration (odds ratio, 1.023; 95% CI, 1.004-1.044; P = .020), and high-density lipoprotein cholesterol level (odds ratio, 0.925; 95% CI, 0.872-0.982; P = .010) were the independent predictors of peripheral arterial stiffness in KT patients.

CONCLUSIONS

Serum fasting leptin level was positively associated with peripheral arterial stiffness among KT patients.

Influence of conversion from calcineurin inhibitors to everolimus on fibrosis, inflammation, tubular damage and vascular function in renal transplant patients

BACKGROUND

Conversion from calcineurin inhibitor (CNI) to mTOR inhibitors may reduce and even halt the progression of chronic allograft dysfunction (CAD) which is the most important cause of renal allograft loss. We aimed to investigate the effects of conversion from CNI to everolimus on parameters of fibrosis, inflammation, glomerulotubular damage and vascular functions in renal transplant recipients.

METHODS

Fifteen stable renal transplant recipients who were under CNI treatment (male/female 13/2, mean age 41 ± 10 years) were enrolled and switched to everolimus. Serum and urinary transforming growth factor-β (TGF-β), urinary neutrophil gelatinase-associated lipocalin (NGAL) and monocyte chemoattractant protein-1 (MCP-1) were measured as markers of fibrosis, tubular damage and inflammation. As parameters of vascular functions, pulse wave velocity (PWV), augmentation index (AIx), serum asymmetric dimethyl-arginine and fibroblast growth factor-23 (FGF-23) were measured. All these measurements were repeated at the 3rd month of conversion.

RESULTS

Estimated GFR (52 ± 7-57 ± 11 ml/min/l.73 m(2), p = 0.02) (was increased after conversion to everolimus. However, serum uric acid levels were significantly decreased (6.21 ± 1.21-5.50 ± 1.39 mg/dL, p = 0.01). Serum TGF-β levels (8727 ± 2897-1943 ± 365 pg/mL, p = 0.03) and urinary NGAL levels (26 ± 10-12 ± 2 ng/mg creatinine, p = 0.05) were significantly decreased. However, urinary MCP-1, FGF-23, PWV and AIx did not change. Urinary TGF-β was associated with urinary NGAL (r = 0.62, p = 0.01), urinary MCP-1 (r = 0.68, p = 0.005) and proteinuria (r = 0.50, p = 0.05).

CONCLUSION

Conversion from CNI to everolimus resulted in significant decreases of serum TGF-β and urinary NGAL which may represent less fibrosis and tubular damage. Association of urinary TGF-β with NGAL and MCP-1 suggests that tubular damage, fibrosis and inflammation may act together for progression of CAD.