Two Decades of Tacrolimus in Renal Transplant: Basic Science and Clinical Evidences

Local delivery of tacrolimus using electrospun poly-ϵ-caprolactone nanofibres suppresses the T-cell response to peripheral nerve allografts

Objective.Repair of nerve gap injuries can be achieved through nerve autografting, but this approach is restricted by limited tissue supply and donor site morbidity. The use of living nerve allografts would provide an abundant tissue source, improving outcomes following peripheral nerve injury. Currently this approach is not used due to the requirement for systemic immunosuppression, to prevent donor-derived cells within the transplanted nerve causing an immune response, which is associated with severe adverse effects. The aim of this study was to develop a method for delivering immunosuppression locally, then to test its effectiveness in reducing the immune response to transplanted tissue in a rat model of nerve allograft repair.Approach.A coaxial electrospinning approach was used to produce poly-ϵ-caprolactone fibre sheets loaded with the immunosuppressant tacrolimus. The material was characterised in terms of structure and tacrolimus release, then testedin vivothrough implantation in a rat sciatic nerve allograft model with immunologically mismatched host and donor tissue.Main results.Following successful drug encapsulation, the fibre sheets showed nanofibrous structure and controlled release of tacrolimus over several weeks. Materials containing tacrolimus (and blank material controls) were implanted around the nerve graft at the time of allograft or autograft repair. The fibre sheets were well tolerated by the animals and tacrolimus release resulted in a significant reduction in lymphocyte infiltration at 3 weeks post-transplantation.Significance.These findings demonstrate proof of concept for a novel nanofibrous biomaterial-based targeted drug delivery strategy for immunosuppression in peripheral nerve allografting.

Adverse Effects of Tacrolimus and Its Associated Risk Factors in Renal Transplant Recipients

OBJECTIVES

Tacrolimus, an important constituent of the immunosuppressant regimen for renal transplant recipients, can result in posttransplant diabetes mellitus. The adverse effect profile of tacrolimus is yet to be completely understood. The relationship between the blood level of tacrolimus and development of posttransplant diabetes mellitus has not been clearly elucidated in Indian populations. We conducted this study to investigate the frequency of posttransplant diabetes mellitus and other adverse effects of tacrolimus, to enumerate the risk factors associated with posttransplant diabetes mellitus development, and to correlate the blood levels of tacrolimus with its occurrence.

MATERIALS AND METHODS

This prospective observational study included 77 renal transplant patients receiving tacrolimus. The blood sugar levels (fasting and postprandial) were monitored, and patients were asked regularly about the adverse effects of tacrolimus experienced by them for 6 months posttransplant. Trough levels of tacrolimus in blood were correlated with occurrence of posttransplant diabetes mellitus.

RESULTS

Posttransplant diabetes mellitus developed in 62.3% (48/77) of renal transplant recipients on a tacrolimus-based regimen. Other adverse effects observed included tremors, diarrhea, alopecia, cyto- megalovirus infection, headache, biopsy-proven calci- neurin inhibitor nephrotoxicity, peripheral neuropathy, and BK virus infection. Higher tacrolimus trough level at month 1 posttransplant was significantly associated with the development of posttransplant diabetes mellitus (adjusted odds ratio = 1.379; 95% CI, 1.02-1.86). The best cutoff of tacrolimus trough level at month 1 posttransplant to reduce the risk of posttransplant diabetes mellitus was 8.1 ng/mL. There was a 5 times increased risk of developing posttransplant diabetes mellitus when tacrolimus trough level at month 1 posttransplant was >8.1 ng/mL (adjusted odds ratio = 5.4; 95% CI, 1.4-19.9).

CONCLUSIONS

Posttransplant diabetes mellitus is a common adverse effect of tacrolimus among renal transplant recipients. A trough level >8.1 ng/mL at month 1 posttransplant was an important predictor for posttransplant diabetes mellitus.

The effect of tacrolimus-induced toxicity on metabolic profiling in target tissues of mice

Tacrolimus (Tac) is a common immunosuppressant that used in organ transplantation. However, its therapeutic index is narrow, and it is prone to adverse side effects, along with an increased risk of toxicity, namely, cardio-, nephro-, hepato-, and neurotoxicity. Prior metabolomic investigations involving Tac-driven toxicity primarily focused on changes in individual organs. However, extensive research on multiple matrices is uncommon. Hence, in this research, the authors systemically evaluated Tac-mediated toxicity in major organs, namely, serum, brain, heart, liver, lung, kidney, and intestines, using gas chromatography-mass spectrometry (GC-MS). The authors also employed multivariate analyses, including orthogonal projections to the latent structure (OPLS) and t-test, to screen 8 serum metabolites, namely, D-proline, glycerol, D-fructose, D-glucitol, sulfurous acid, 1-monopalmitin (MG (16:0/0:0/0:0)), glycerol monostearate (MG (0:0/18:0/0:0)), and cholesterol. Metabolic changes within the brain involved alterations in the levels of butanamide, tartronic acid, aminomalonic acid, scyllo-inositol, dihydromorphine, myo-inositol, and 11-octadecenoic acid. Within the heart, the acetone and D-fructose metabolites were altered. In the liver, D-glucitol, L-sorbose, palmitic acid, myo-inositol, and uridine were altered. In the lung, L-lactic acid, L-5-oxoproline, L-threonine, phosphoric acid, phosphorylethanolamine, D-allose, and cholesterol were altered. Lastly, in the kidney, L-valine and D-glucose were altered. Our findings will provide a systematic evaluation of the metabolic alterations in target organs within a Tac-driven toxicity mouse model.

Lactobacillus acidophilus Supplementation Exerts a Synergistic Effect on Tacrolimus Efficacy by Modulating Th17/Treg Balance in Lupus-Prone Mice via the SIGNR3 Pathway

Objective

Tacrolimus (Tac) is an immunosuppressant used in the treatment of systemic lupus erythematosus (SLE); however, it induces T cell subset imbalances by reducing regulatory T (Treg) cells. Lactobacillus acidophilus (LA) is reported to have therapeutic efficacy in immune-mediated diseases via T cell regulation.

Methods

This study investigated whether a combination therapy of LA and Tac improves the therapeutic efficacy of Tac by modulating T cell subset populations in an animal model of SLE. Eight-week-old MRL/lpr mice were orally administered with 5 mg/kg of Tac and/or 50 mg/kg of LA daily for 8 weeks. Cecal microbiota compositions, serum autoantibodies levels, the degree of proteinuria, histological changes in the kidney, and populations of various T cell subsets in the spleen were analyzed.

Results

Mice presented with significant gut dysbiosis, which were subsequently recovered by the combination treatment of Tac and LA. Double negative T cells in the peripheral blood and spleens of MRL/lpr mice were significantly decreased by the combination therapy. The combination treatment reduced serum levels of anti-dsDNA antibodies and Immunoglobulin G2a, and renal pathology scores were also markedly alleviated. The combination therapy induced Treg cells and decreased T helper 17 (Th17) cells both in vitro and in vivo. In vitro treatment with LA induced the production of indoleamine-2,3-dioxygenase, programmed death-ligand 1, and interleukin-10 via the specific intracellular adhesion molecule-3 grabbing non-integrin homolog-related 3 receptor signals.

Conclusion

The present findings indicate that LA augments the therapeutic effect of Tac and modulates Th17/Treg balance in a murine model of SLE.

Protective effects of selenium in tacrolimus-induced lung toxicity: potential role of heme oxygenase 1

The present study aimed to evaluate the protective effects of selenium (Sel) administration against tacrolimus (Tac) - induced lung toxicity and to assess the relation between heme oxygenase 1 (HO-1) and these effects. The study was conducted on 36 Wistar male albino rats equally divided into four groups: (i) normal control; (ii) Sel (0.1 mg/kg per day p.o. for four weeks); (iii) TAC 3 mg/mL as single oral dose on 27th day; and (iv) Tac + Sel. Lung tissues, lung homogenate, and bronchoalveolar lavage of the sacrificed animals were investigated biochemically and histopathologically, by immunohistochemistry or by PCR. The Tac group showed significantly lower expression of HO-1. Administration of Sel was associated with increased HO-1 expression. Oxidative (malondialdehyde, reduced glutathione, superoxide dismutase, myeloperoxidase, and glutathione peroxidase activity) and nitrosative stress (nitric oxide) markers and markers of inflammation (interleukin 1β (IL-1β), IL-6, and IL-10) showed changes corresponding to HO-1 levels in rat groups. Tac group showed the highest expression of caspase-3. Sel exerted a protective role against Tac-induced lung toxicity.

Utilization of Mycophenolic Acid, Azathioprine, Tacrolimus, Cyclosporin, Sirolimus, and Everolimus: Multinational Study

Background: Organ transplantations are difficult, complicated and very expensive interventions. In order to preserve the transplanted organs, it is necessary to provide medical care to the patients in terms of immunosuppression. According to the guidelines, the first-line therapy choices for achieving immunosuppression after transplantation are tacrolimus, cyclosporine, mycophenolic acid, azathioprine, sirolimus, everolimus„ and corticosteroids. The aim of our study was to examine the utilization of this drugs in Montenegro and to compare the results with the ones from Finland, Croatia, and Serbia.

Methods: In our investigation we used Anatomical Therapeutic Chemical/Defined Daily Dose (ATC/DDD) methodology. Prices per DDD of drugs are presented in euros (€).

Results: In all observed countries, there is a positive trend in the consumption of all 6 drugs during the analyzed period. The prices per DDD of these drugs generally show a negative trend. Tacrolimus and mycophenolic acid in Montenegro recorded the largest reduction in the price per DDD. Price per one DDD of tacrolimus decreased from €13.28 in 2009 to €5.11 in 2019, thus by about 260%, and as regards mycophenolic acid, the price per one DDD decreased from €9.59 in 2009 to € 3.36 in 2019, thus by almost 300%.

Conclusion: Despite the reduction in the price per DDD, drugs that are used as immunosuppressants are showing increasing costs from year to year. Since these drugs are expensive, they participate in a significant percentage in the budget for medicines in each country.

Potential Application of T-Follicular Regulatory Cell Therapy in Transplantation

Regulatory T cells (Tregs) constitute a small proportion of circulating CD4⁺ T cells that function to maintain homeostasis and prevent autoimmunity. In light of their powerful immunosuppressive and tolerance-promoting properties, Tregs have become an interesting potential candidate for therapeutic use in conditions such as solid organ transplant or to treat autoimmune and inflammatory conditions. Clinical studies have demonstrated the safety of polyclonally expanded Tregs in graft-versus-host disease, type 1 diabetes, and more recently in renal and liver transplantation. However, Tregs are heterogenous. Recent insights indicate that only a small proportion of Tregs, called T follicular regulatory cells (Tfr) regulate interactions between B cells and T follicular helper (Tfh) cells within the germinal center. Tfr have been mainly described in mouse models due to the challenges of sampling secondary lymphoid organs in humans. However, emerging human studies, characterize Tfr as being CD4⁺CD25⁺FOXP3⁺CXCR5⁺ cells with different levels of PD-1 and ICOS expression depending on their localization, in the blood or the germinal center. The exact role they play in transplantation remains to be elucidated. However, given the potential ability of these cells to modulate antibody responses to allo-antigens, there is great interest in exploring translational applications in situations where B cell responses need to be regulated. Here, we review the current knowledge of Tfr and the role they play focusing on human diseases and transplantation. We also discuss the potential future applications of Tfr therapy in transplantation and examine the evidence for a role of Tfr in antibody production, acute and chronic rejection and tertiary lymphoid organs. Furthermore, the potential impact of immunosuppression on Tfr will be explored. Based on preclinical research, we will analyse the rationale of Tfr therapy in solid organ transplantation and summarize the different challenges to be overcome before Tfr therapy can be implemented into clinical practice.

Calcineurin phosphatase activity regulates Varicella-Zoster Virus induced cell-cell fusion

Cell-cell fusion (abbreviated as cell fusion) is a characteristic pathology of medically important viruses, including varicella-zoster virus (VZV), the causative agent of chickenpox and shingles. Cell fusion is mediated by a complex of VZV glycoproteins, gB and gH-gL, and must be tightly regulated to enable skin pathogenesis based on studies with gB and gH hyperfusogenic VZV mutants. Although the function of gB and gH-gL in the regulation of cell fusion has been explored, whether host factors are directly involved in this regulation process is unknown. Here, we discovered host factors that modulated VZV gB/gH-gL mediated cell fusion via high-throughput screening of bioactive compounds with known cellular targets. Two structurally related non-antibiotic macrolides, tacrolimus and pimecrolimus, both significantly increased VZV gB/gH-gL mediated cell fusion. These compounds form a drug-protein complex with FKBP1A, which binds to calcineurin and specifically inhibits calcineurin phosphatase activity. Inhibition of calcineurin phosphatase activity also enhanced both herpes simplex virus-1 fusion complex and syncytin-1 mediated cell fusion, indicating a broad role of calcineurin in modulating this process. To characterize the role of calcineurin phosphatase activity in VZV gB/gH-gL mediated fusion, a series of biochemical, biological and infectivity assays was performed. Pimecrolimus-induced, enhanced cell fusion was significantly reduced by shRNA knockdown of FKBP1A, further supporting the role of calcineurin phosphatase activity in fusion regulation. Importantly, inhibition of calcineurin phosphatase activity during VZV infection caused exaggerated syncytia formation and suppressed virus propagation, which was consistent with the previously reported phenotypes of gB and gH hyperfusogenic VZV mutants. Seven host cell proteins that remained uniquely phosphorylated when calcineurin phosphatase activity was inhibited were identified as potential downstream factors involved in fusion regulation. These findings demonstrate that calcineurin is a critical host cell factor pivotal in the regulation of VZV induced cell fusion, which is essential for VZV pathogenesis.

Administration of FK506 from Late Stage of Disease Prolongs Survival of Human Prion-Inoculated Mice

Human prion diseases are etiologically categorized into three forms: sporadic, genetic, and infectious. Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common type of human prion disease that manifests as subacute progressive dementia. No effective therapy for sCJD is currently available. Potential therapeutic compounds are frequently tested in rodents infected with mouse-adapted prions that differ from human prions. However, therapeutic effect varies depending on the prion strain, which is one of the reasons why candidate compounds have shown little effect in sCJD patients. We previously reported that intraperitoneal administration of FK506 was able to prolong the survival of mice infected with a mouse-adapted prion by suppressing the accumulation of abnormal prion protein (PrP) and inhibiting the activation of microglia. In this study, we tested oral administration of FK506 in knock-in mice expressing chimeric human prion protein (KiChM) that were infected with sCJD to determine if this compound is also effective against a clinically relevant human prion, i.e., one that has not been adapted to mice. Treatment with FK506, started either just before or just after disease onset, suppressed typical sCJD pathology (gliosis) and slightly but significantly prolonged the survival of sCJD-inoculated mice. It would be worthwhile to conduct a clinical trial using FK506, which has been safety-approved and is widely used as a mild immunosuppressant.

The Effect of Maintenance Treatment with Twice-Daily or Prolonged Once-Daily Tacrolimus Formulation on Visual Evoked Potentials in Stable Kidney Transplant Recipients

In kidney transplant recipients (KTRs), uraemia-induced central nervous system damage partly subsides, while the long-lasting exposure to tacrolimus may cause pathologic visual evoked potentials (VEP) findings, which have not been investigated yet. Thus, the aim of the present study was to assess the effect of tacrolimus maintenance treatment on bioelectrical function of optic nerves in stable KTRs. Sixty-five stable KTRs were enrolled, including 30 patients treated with twice-daily (Prograf) and 35 patients treated with prolonged once-daily (Advagraf) tacrolimus formulation. In all patients, pattern and flash VEP measurements were performed. Tacrolimus dosing and exposure were also analyzed. Overall, 129 eyes were analyzed. In pattern VEP, both (1°) and (15') latencies of P100 waves were significantly longer, whereas (1°) and (15') amplitudes were lower in the Advagraf group as compared with the Prograf group. Multivariate regression analyses revealed that the use of Advagraf (vs. Prograf) was independently associated with longer (1°) and (15') P100 latencies and lower corresponding amplitudes, whereas log tacrolimus daily dose was only related to amplitudes in a whole study group. In flash VEP, log tacrolimus trough level was associated with negative changes in P2 wave amplitude irrespective of tacrolimus formulation, whereas its association with P2 latency was observed only in the Prograf group. Both the type of tacrolimus formulation and drug exposure influenced the VEP parameters in stable KTRs.

Tacrolimus in non-Asian patients with SLE: a real-life experience from three European centres

Objectives

To analyse the real-life practice on the use of Tacrolimus (TAC) in patients with systemic lupus erythematosus (SLE) from three European SLE referral centres.

Methods

Adult patients with SLE regularly followed at three European referral centres were included. Demographics, cumulative organ involvement, treatment history, Systemic Lupus Disease Activity Index (SLEDAI), laboratory features and physician's judgement were collected at baseline and at 3-6-12 months after starting TAC.

Results

29 patients were included (89% female, mean age 38±9 years). Ethnicity was predominantly Caucasian (82%), Black African (11%), Hispanic (3.5%) and Caribbean (3.5%). The main indications for TAC prescription were renal involvement (82.7%), arthritis (10.3%), cutaneous manifestations (6.8%), haematological manifestations (6.8%), serositis (3.4%). At 3 months, there was a clinical improvement in 21 patients (72.4%) and 9 of these experienced a complete resolution of symptoms (31%). This corresponds to: (1) a significant decrease in the mean SLEDAI; (2) a significant decrease in the mean 24  hours proteinuria; a significant increase in C3 and stable creatinine values. At 6 months (n=25), the physician declared an improvement in 19 patients (76%) and a complete resolution of symptoms in 9 (36%). The same trend was observed at 12 months of follow-up. TAC was discontinued in nine pts (31%); reasons for discontinuation were inefficacy (13.8%), drug intolerance (10%) and disease remission (6.9%).

Conclusions

Despite the limitation due to the small number of patients and the uncontrolled nature of the study, these data show that TAC can be considered a valid therapeutic option in patients with SLE, especially for renal involvement.

Nutritional Requirements of Lung Transplant Recipients: Challenges and Considerations

An optimal nutritional status is associated with better post-transplant outcomes and survival. Post-lung transplant nutrition management is however particularly challenging as lung recipients represent a very heterogeneous group of patients in terms of age, underlying diseases, weight status and presence of comorbidities. Furthermore, the post-transplant period encompasses several stages characterized by physiological and pathophysiological changes that affect nutritional status of patients and necessitate tailored nutrition management. We provide an overview of the current state of knowledge regarding nutritional requirements in the post-lung transplant period from the immediate post-operative phase to long-term follow-up. In the immediate post-transplantation phase, the high doses of immunosuppressants and corticosteroids, the goal of maintaining hemodynamic stability, the presence of a catabolic state, and the wound healing process increase nutritional demands and lead to metabolic perturbations that necessitate nutritional interventions. As time from transplantation increases, complications such as obesity, osteoporosis, cancer, diabetes, and kidney disease, may develop and require adjustments to nutrition management. Until specific nutritional guidelines for lung recipients are elaborated, recommendations regarding nutrient requirements are formulated to provide guidance for clinicians caring for these patients. Finally, the management of recipients with special considerations is also briefly addressed.