Increased Sensitivities of Peripheral Blood Mononuclear Cells to Immunosuppressive Drugs in Cirrhosis Patients Awaiting Liver Transplantation

Current methods of the analysis of immunosuppressive agents in clinical materials: A review

More than 100000 solid organ transplantations are performed every year worldwide. Calcineurin (cyclosporine A, tacrolimus), serine/threonine kinase (sirolimus, everolimus) and inosine monophosphate dehydrogenase inhibitor (mycophenolate mofetil), are the most common drugs used as immunosuppressive agents after solid organ transplantation. Immunosuppressive therapy, although necessary after transplantation, is associated with many adverse consequences, including the formation of secondary metabolites of drugs and the induction of their side effects. Calcineurin inhibitors are associated with nephrotoxicity, cardiotoxicity and neurotoxicity; moreover, they increase the risk of many diseases after transplantation. The review presents a study of the movement of drugs in the body, including the processes of absorption, distribution, localisation in tissues, biotransformation and excretion, and also their accompanying side effects. Therefore, there is a necessity to monitor immunosuppressants, especially because these drugs are characterised by narrow therapeutic ranges. Their incorrect concentrations in a patient's blood could result in transplant rejection or in the accumulation of toxic effects. Immunosuppressive pharmaceuticals are macrolide lactones, peptides, and high molecular weight molecules that can be metabolised to several metabolites. Therefore the two main analytical methods used for their determination are high performance liquid chromatography with various detection methods and immunoassay methods. Despite the rapid development of new analytical methods of analysing immunosuppressive agents, the application of the latest generation of detectors and increasing sensitivity of such methods, there is still a great demand for the development of highly selective, sensitive, specific, rapid and relatively simple methods of immunosuppressive drugs analysis.

Clinical significance of peripheral blood lymphocyte sensitivity to glucocorticoids for the differentiation of high-risk patients with decreased allograft function after glucocorticoid withdrawal in renal transplantation

PURPOSE

A reliable biomarker to differentiate high-risk recipients who will experience a decrease in allograft function after glucocorticoid withdrawal has not been established in renal transplantation. We examined the clinical significance of peripheral blood lymphocyte sensitivity to glucocorticoids in vitro for the differentiation of the high-risk patients after glucocorticoid reduction/withdrawal in renal transplant recipients.

METHODS

The study included 44 renal transplant recipients with stable allograft function. Peripheral lymphocyte responses to suppressive effects of cortisol, methylprednisolone, cyclosporine, and tacrolimus in mitogen assay procedures in vitro were examined. Clinical outcome after glucocorticoid reduction/withdrawal was retrospectively compared between recipients with lymphocytes normally sensitive to the drugs and those with hyposensitivity. The receiver-operating characteristic (ROC) curve analysis was undertaken for setting the cutoff IC50 values of the drugs against the T cell mitogen-induced lymphocyte proliferation to differentiate the high-risk recipients with decreased allograft function after glucocorticoid withdrawal.

FINDINGS

The median (range) IC50 value for cortisol in the recipients who showed decreased renal function due to glucocorticoid withdrawal was 10,000 (570.9-72,279.3) ng/mL (n = 9), which was significantly higher than the value of 351.6 (2.0-10,000) ng/mL in the recipients who had not experienced glucocorticoid withdrawal symptoms (n = 35) (P < 0.001). Similarly, the median (range) IC50 value for methylprednisolone in the recipients who showed decreased renal function after glucocorticoid withdrawal was 69.1 (21.5-1442.7) ng/mL (n = 9), which was significantly higher than the value of 13.8 (0.7-1000) ng/mL in the recipients who had not experienced glucocorticoid withdrawal symptoms (n = 30) (P < 0.003). In contrast, there was no significant difference in the median IC50 values of cyclosporine and tacrolimus between the 2 recipient subgroups. The ROC curve analyses for the IC50 values of the immunosuppressive drugs estimated the cutoff value of cortisol and methylprednisolone to be 3580.0 and 21.5 ng/mL, respectively. The ROC AUCs for cortisol and methylprednisolone were 0.83 and 0.84, respectively. According to the cutoff IC50 value, the incidence of decreased allograft function in the low cortisol sensitivity (IC50 >3580.0 ng/mL) subgroup was 7 of 13 patients, which was significantly higher than that of the higher sensitivity subgroup of 2 of 31 (P = 0.0012). A similar case was observed using the cutoff IC50 value of methylprednisolone (P = 0.0012), whereas recipient grouping according to the cutoff IC50 values of cyclosporine and tacrolimus failed to differentiate the high-risk recipients with decreased allograft function after glucocorticoid withdrawal.

IMPLICATIONS

Glucocorticoid pharmacodynamics in lymphocytes of individual patient origin is a reliable biomarker for differentiation of renal transplant recipients who will experience a safe reduction/withdrawal of glucocorticoid.

Comparative Study of the Cellular Pharmacodynamics of Tacrolimus in Renal Transplant Recipients Treated with and without Basiliximab

Basiliximab is a recently developed immunosuppressive agent for the prevention of acute allograft rejection in renal transplant recipients. The combination use of basiliximab and a calcineurin inhibitor was suggested to be more effective in comparison to immunosuppressive therapy using calcineurin inhibitor without basiliximab. Cyclosporine has been generally administered with basiliximab for renal transplant recipients. However, in cases of tacrolimus-based immunosuppressive regimen, the clinical efficacy and safety of combined use of tacrolimus and basiliximab remains to be elucidated. This study evaluated the tacrolimus pharmacological efficacy using a lymphocyte immunosuppressant sensitivity test (LIST) with MTT assay procedures in 16 cases of renal transplant recipients treated by tacrolimus without basiliximab and in 13 cases treated by tacrolimus in combination with basiliximab. The rate of acute rejection episodes in the recipients treated with tacrolimus plus basiliximab was 1/13 (7.7%), whereas the rate in the recipients treated with tacrolimus without basiliximab was 6/16 (37.5%). The recipients were divided into two groups according to their peripheral blood mononuclear cell (PBMC) sensitivity to tacrolimus [i.e., including a tacrolimus high sensitivity group (IC50 <1.0 ng/ml) and a low sensitivity group (IC50 >1.0 ng/ml). In the recipients treated with tacrolimus without basiliximab, the rate of acute rejection episodes in the tacrolimus high sensitivity group was 1/10 (10.0%), which was significantly lower than the rate in the low sensitivity group of 5/6 (83.3%; p = 0.008). The incidence of cytomegalovirus infection was not significantly different between the tacrolimus high and the low sensitivity groups of the recipients treated with tacrolimus with and without basiliximab. Therefore, in the case of selected tacrolimus-based immunosuppressive therapy for renal transplant recipients, the tacrolimus pharmacological efficacy should be evaluated using LIST at a time just before the transplant procedure in order to accurately predict allograft rejection. The data also suggested that low tacrolimus sensitivity recipients should be treated with tacrolimus-based immunosuppressive therapy in combination with basiliximab.

Comparative study of the cellular pharmacodynamics of calcineurin inhibitors between patients with chronic renal failure awaiting renal transplantation and cirrhosis patients awaiting liver transplantation

The in vitro response of peripheral blood mononuclear cells (PBMCs) to the suppressive effects of calcineurin inhibitors is known to correlate with the clinical efficacy of drugs used in renal transplantations. The present study was conducted to examine the differences of PBMC responses to calcineurin inhibitors between chronic renal failure (CRF) patients awaiting renal transplantation and cirrhosis patients awaiting liver transplantation. The study included 99 CRF patients awaiting renal transplantation and 27 cirrhosis patients awaiting liver transplantation. Twenty milliliters of venous blood was taken 1-7 days before transplantation. The in vitro drug concentrations giving 50% inhibition of PBMC blastogenesis stimulated with concanavalin A (IC(50)s) were calculated. The suppressive effects of tacrolimus against PBMC blastogenesis were more than 10-100 times stronger than those of cyclosporine. The median IC(50) value for cyclosporine against the CRF PBMCs was not significantly different from the median IC(50) value against the cirrhosis PBMCs. In contrast, tacrolimus sensitivity in cirrhosis PBMCs is approximately seven times higher than that in CRF PBMCs. The median IC(50) value for tacrolimus against cirrhosis PBMCs was significantly lower and therefore the effect was stronger in comparison to the CRF PBMCs (p < 0.001). These data suggest that the PBMCs of cirrhosis patients, in comparison to those of CRF patients, are highly sensitive to the suppressive effect of tacrolimus. However, PBMC sensitivity to cyclosporine was not significantly different between the CRF and cirrhosis patients. These observations raise the possibility that treatment with tacrolimus, rather than cyclosporine, may therefore be a better choice to reduce the risks of allograft rejection in liver transplantation.

Clinical Significance of the Cellular Pharmacodynamics of Tacrolimus in Living-Donor Liver Transplantation

Successful immunosuppressive therapy is critical for liver transplantation; however, a considerable number of patients experience fatal rejection or alternatively exhibit serious infection resulting from excessive immunosuppression. The in vitro tacrolimus response of peripheral blood mononuclear cells (PBMCs) before transplantation was compared to the clinical outcome up to 4 weeks after operation in 28 living-donor liver transplant recipients treated with tacrolimus. The tacrolimus IC50 values against concanavalin A-induced PBMC blastogenesis in vitro were calculated. These recipients were classified into two groups with the mean tacrolimus IC50 (0.18 ng/ml) as the cutoff point, after which the clinical outcome between the patient groups was compared. The allograft rejection incidence in the low-sensitivity group (IC50 < 0.18 ng/ml; n = 16) was 6/12 (50.0%), which was significantly higher than the incidence of 2/16 (12.5%) in the high-sensitivity group (IC50 > 0.18 ng/ml; n = 12) ( p = 0.0297). In contrast, the infection incidence in the high-sensitivity group was 6/16 (37.5%), which was significantly higher than that of the low-sensitivity group (1/12; 8.3%) ( p = 0.0401). These data suggest that patients exhibiting a low PBMC sensitivity to tacrolimus have a risk of rejection, whereas highly sensitive patients have a risk of infection in living-donor liver transplantations under tacrolimus therapy.

Influence of bacterial superantigen TSST-1 against the anti-proliferative efficacy of immunosuppressive drugs and interleukin 2 production in peripheral blood mononuclear cells of hemodialysis patients and healthy subjects

We investigated the influence of bacterial superantigen on the efficacies of immunosuppressive drugs on the blastogenesis of peripheral-blood mononuclear cells of 27 hemodialysis patients awaiting renal transplantation. The IC(50) values for prednisolone, methylprednisolone, cyclosporine, and tacrolimus evaluated in the superantigen-stimulated cells were significantly higher than those evaluated in concanavalin A-stimulated cells (p = 0.0002-0.018). Interleukin-2 amounts produced from superantigen-stimulated cells were significantly larger than those from concanavalin A-stimulated cells (p = 0.0363). These results suggest that superantigen attenuates the suppressive efficacies of glucocorticoids and calcineurin inhibitors by stimulating lymphocytes of hemodialysis patients awaiting transplantation to overproduce interleukin-2.