Tacrolimus: A Review of Laboratory Detection Methods and Indications for Use

Bright nanoparticle-labeled lateral flow immunoassay for rapid quantitative detection of tacrolimus in human plasma

Tacrolimus (Tac), a macrolide immunosuppressant widely employed in organ transplantation, requires therapeutic drug monitoring owing to the narrow treatment window. In this study, we established an innovative ultrabright nanoparticle-based lateral flow immunoassay (LFIA) for one-step rapid quantitative detection of Tac in human plasma. The aggregation-induced emission (AIE) luminogen, AIE490, was embedded in polystyrene nanoparticles to assemble the ultrabright AIE490NP as a highly sensitive fluorescence marker. Carboxyl-modified Tac was used to couple with carrier proteins to synthesize complete antigens coated on the test line. Under optimized conditions, the limit of detection for Tac is 0.589 ng/mL in human plasma. The linear range was 1-1000 ng/mL, completely covering the safe plasma concentration of Tac, 5-15 ng/mL. The intra- and inter-assay precisions of the established method are below 17.99% and 19.94%, respectively. In addition, for measuring the plasma concentration of Tac in 139 clinical samples, the results of the LFIA are consistent with those of LC-MS/MS (R2 = 0.8520, P < 0.0001). Therefore, the established LFIA demonstrates comparable reliability to the LC-MS/MS and holds great potential as a rapid quantitative detection method of Tac in human plasma.

Marine Natural Products in Inflammation-Related Diseases: Opportunities and Challenges

In recent decades, the potentiality of marine natural products (MNPs) in the medical field has been increasingly recognized. Natural compounds derived from marine microorganisms, algae, and invertebrates have shown significant promise for treating inflammation-related diseases. In this review, we cover the three primary sources of MNPs and their diverse and unique chemical structures and bioactivities. This review aims to summarize the progress of MNPs in combating inflammation-related diseases. Moreover, we cover the functions and mechanisms of MNPs in diseases, highlighting their functions in regulating inflammatory signaling pathways, cellular stress responses, and gut microbiota, among others. Meanwhile, we focus on key technologies and scientific methods to address the current limitations and challenges in MNPs.

Effect of immunosuppression on hESC-derived retina organoids in vitro and in vivo

BACKGROUND

Photoreceptor (PR) enriched retinal organoid (RO) sheets (human embryonic stem cell [hESC]-derived ROs) resulted in restoration of visual acuity in immunocompromised retinal degenerate (RD) animal models after transplantation. Further assessment of their clinical potential requires evaluation in immunocompetent RD disease models with effective immune suppression. We characterized safety and efficacy profiles of both donor tissues and prospective immunosuppressive treatments in vitro; and in vivo in immunocompetent RD rats (strain SD-foxn1 Tg(S334ter)3Lav).

METHODS

Retinal identity of ROs was validated by histology, flow cytometry and gene expression profiling, and their immunogenicity to sensitized human immune cells was measured by mixed lymphocyte reactions (MLR). We measured the effect of RO exposure for 1-4 weeks to therapeutic concentrations of our immunosuppressant drugs of choice on gene expression and metabolic function using quantitative PCR (qPCR) and functional and structural fluorescence lifetime imaging (FLIM), respectively. Immunocompetent RD graft recipients were immunosuppressed by implanted tacrolimus (TAC) pellets and mycophenolate mofetil (MMF) in food. In vivo, LCMS aided assessments of drug pharmacodynamics. Flow cytometry immunophenotyping and assay of post-surgery cytokines were used to assess and monitor drug efficacy. Retinal transplants were imaged in situ using optical coherence tomography (OCT) at defined time points post-surgery. Visual function was assessed by optokinetic tests (OKT) and superior colliculus electrophysiology recording. At study endpoints, immune cell infiltration and donor photoreceptor engraftment into host retinal architecture was evaluated by immunohistochemistry.

RESULTS

Immunosuppressive drugs have no negative effects on RO development and metabolism in vitro; and low alloreactivity of ROs determined by MLR may be predictive to that of human graft recipients. In vivo, minimum effective dosing ranges of TAC and MMF were determined. We characterized the mechanisms and critical immune populations implicated in rejection; and subsequently demonstrated their effective suppression in our xenograft RD model. OKT measured significant visual improvement after RO transplantation. Transplants developed most retinal cell types including photoreceptors; and integrated with the host retina. However, immunosuppression induced higher sensitivity to ketamine anesthesia.

CONCLUSIONS

This study proves the concept that immunosuppression is likely tolerable in retinal transplantation and human stem cell therapy for retinal degeneration patients.

Tacrolimus regulates extracellular vesicle secretion from T cells via autophagy-lysosomal pathway

Extracellular vesicles (EVs) derived from T cells have been proposed to mediate intercellular communication and orchestrate immune responses. The immunosuppressive drug, tacrolimus (TAC), suppresses T cell activity; however, the impact of TAC on T cell-derived EVs remains primarily unexplored. In this study, human primary T cells purified from healthy donors were used to investigate TAC-mediated regulation of EV secretion by T cells. Using size exclusion chromatography (SEC) to isolate EVs released by T cells, we found that the number of released EVs was increased upon anti-CD3/CD28 bead-mediated activation. Furthermore, pre-treatment with TAC before activation had a potentiating effect on EV release, as evidenced by western blot analysis of EV markers and small particle flow cytometry. In addition, we showed that EVs isolated from the plasma of TAC-treated kidney transplant patients were increased compared to those observed with pre-transplant plasma. Upon examining the mechanism underlying the action of TAC, we found that TAC impaired autophagy-lysosome-mediated degradation by inhibiting the nuclear translocation of transcription factor EB, a master regulator of lysosomal biogenesis. Notably, the addition of trehalose, an autophagy inducer, abrogated the TAC-induced EV release, indicating that TAC regulated EV secretion via the autophagy-lysosomal pathway. At the functional level, we demonstrated that EVs from TAC-treated T cells carried a decreased amount of CD40L, a protein critical for the activation of the adaptive immune response. Collectively, these findings demonstrate that an overall increase in EV production and decreased CD40L levels in EVs are characteristic responses of T cells to TAC.

Enhanced eNOS/nitric oxide production by nebivolol interferes with TGF-β1/Smad3 signaling and collagen I deposition in the kidney after prolonged tacrolimus administration

AIMS

Tacrolimus is an effective immunosuppressant commonly used post-transplantation and in certain autoimmune diseases. However, its long-term administration is associated with renal fibrosis through transforming growth factor-beta/suppressor of mother against decapentaplegic (TGF-β/Smad) signaling that could be partly attributed to endothelial dysfunction alongside decreased nitric oxide (NO) release. Our study aimed to investigate the prospective renal anti-fibrotic effect of enhanced NO production by nebivolol against tacrolimus-stimulated TGF-β1/Smad3 signaling.

MATERIALS AND METHODS

To illustrate the proposed mechanism of nebivolol, Nω-nitro-L-arginine methyl ester (L-NAME); nitric oxide synthase inhibitor; was co-administered with nebivolol. Rats were treated for 30 days as control, tacrolimus, tacrolimus/nebivolol, tacrolimus/L-NAME, and tacrolimus/nebivolol/L-NAME groups.

KEY FINDINGS

Our results revealed that renal NO content was reduced in tacrolimus-treated rats, while treatment with tacrolimus/nebivolol enhanced NO content via up-regulated endothelial nitric oxide synthase (eNOS), but down-regulated inducible nitric oxide synthase (iNOS) expression. That participated in the inhibition of TGF-β1/Smad3 signaling induced by tacrolimus, where the addition of L-NAME abolished the defensive effects of nebivolol. Subsequently, the deposition of collagen I and alpha-smooth muscle actin (α-SMA) was retarded by nebivolol, emphasized by reduced Masson's trichrome staining. In accordance, there was a strong negative correlation between eNOS and both TGF-β1 and collagen I protein expression. The protective effects of nebivolol were further confirmed by the improvement in kidney function biomarkers and histological features.

SIGNIFICANCE

It can be suggested that treatment with nebivolol along with tacrolimus could effectively suppress renal TGF-β1/Smad3 fibrotic signaling via the enhancement of endothelial NO production, thus curbing renal fibrosis development.

Severe Left Main Coronary Artery Stenosis and Aortic Regurgitation in a Patient Presenting with Takayasu Arteritis

We herein report the case of a 46-year-old woman with Takayasu arteritis (TA), severe stenosis in the left main coronary artery (LMCA), and severe aortic regurgitation. Prednisolone and tacrolimus were initiated as TA treatments. Two months after initiating medical therapy, the aortic regurgitation severity improved to a moderate grade, although there was no obvious improvement in LMCA stenosis. Thus, after confirming the resolution of inflammation, we performed coronary artery bypass grafting alone without any aortic valve intervention. In TA patients with severe LMCA stenosis, surgical management of the coronary artery should therefore be considered only after successfully administering anti-inflammatory therapy.

Tacrolimus and Cyclosporin Pharmacotherapy, Detection Methods, Cytochrome P450 Enzymes after Heart Transplantation

BACKGROUND

Advances in organ transplantation were made after the discovery of the pure form of cyclosporine by Dr Jean Borel in the 1970s. In fact, in clinical practice achieving a delicate balance in circulating immunosuppressive necessitate focus on the difficult task of posttransplant therapeutic drug monitoring.

OBJECTIVE

The purpose of this study was to determine the pharmacologic properties of cyclosporine- tacrolimus, detection methods, and the effects on the activity of cytochrome P450 enzymes when prescribing the most efficient treatments in forms of polypharmacy for the recipients of heart transplantation.

METHODS

Scientific literature on the interactions of tacrolimus and cyclosporine with human cytochrome P450 enzymes was searched using PUBMED.Gov (https://pubmed.ncbi.nlm.nih.gov/), Web of Science, and Scopus.

RESULTS

Prescription immunosuppressive drugs based on polypharmacy accompanied by induction agents could result in hidden neurotoxicity and nephrotoxicity. A literature search shows that cyclosporine prescription with antihypertensives drugs needs close monitoring. Co-administration of tacrolimus and diltiazem or verapamil needs a decrease in the tacrolimus dose by 20-50%. Vigilant attention to the lowest possible statin dose is needed when coadministered with fluvastatin or pravastatin. Polypharmacy based on ticlopidine, clopidogrel, and cyclosporine or tacrolimus needs monitoring of immunosuppressive drug levels for several months. A prescription with clotrimazole or fluconazole needs close monitoring, and itraconazole or ketoconazole needs to reduce the initial dose by 50%. Combination with nefazodone needs to be avoided, and alternative drugs such as sertraline or citalopram could be prescribed in addition to further monitoring consideration. In prescription with phenytoin, the bound and free phenytoin levels need close monitoring.

CONCLUSION

Polypharmacy based on tacrolimus or cyclosporine needs vigilant therapeutic drug monitoring due to the cytochrome P450 enzymes associated with biochemical variables in metabolic pathways. Further attention to polypharmacy should be given to circulate drugs that could hide pharmacokinetics interactions associated with infections, malignancies, chronic kidney disease, and rejection after organ transplantation.

Use of volumetric absorptive microsampling and parallel reaction monitoring mass spectrometry for tacrolimus blood trough measurements at home in pediatric heart transplant patients

Background

Measurement of trough levels for calcineurin inhibitors by venipuncture sampling is a mainstay of patient management in solid organ transplant recipients but challenging in pediatric patients. Volumetric Absorptive Microsampling (VAMS) is a patient-friendly, minimally invasive sampling technique to accurately collect blood. An assay for measurement of tacrolimus in blood using VAMS, coupled with parallel reaction monitoring (PRM) mass spectrometry, was validated in pediatric heart transplant patients.

Methods

Tacrolimus was measured by a newly developed high-resolution PRM assay and compared with low-resolution tandem mass spectrometry (MRM). Dried blood samples were collected from pediatric heart transplant patients (n = 35) using VAMS devices and a satisfaction survey was completed by patients/guardians. Tacrolimus concentrations were compared across whole liquid blood, dried blood spots, and capillary blood, and shipping stability determined.

Results

The PRM assay was linear over a range 1-50 ng/mL, similar to MRM but had greater specificity due to reduced background noise. No significant differences in tacrolimus concentrations were observed between VAMS and venous blood. Tacrolimus dried on VAM tips was stable for 14 days and concentrations were unaffected by postal shipping. The variability in two simultaneously collected at-home patient samples was minimal - average concentration difference was 0.12 ± 0.94 ng/mL (p = 0.6) between paired samples.

Conclusion

A high resolution PRM mass spectrometry assay was developed for home-based dried blood collections for therapeutic monitoring of tacrolimus. The advantage of PRM was enhanced specificity and the VAMS devices provided a simple and convenient approach to blood sampling at home in pediatric heart transplant patients.

Immunosuppressive Agents-Effects on the Cardiovascular System and Selected Metabolic Aspects: A Review

The widespread use of immunosuppressive drugs makes it possible to reduce inflammation in autoimmune diseases, as well as prevent transplant rejection in organ recipients. Despite their key action in blocking the body's immune response, these drugs have many side effects. These actions primarily affect the cardiovascular system, and the incidence of complications in patients using immunosuppressive drugs is significant, being associated with a higher incidence of cardiovascular incidents such as myocardial infarction and stroke. This paper analyzes the mechanisms of action of commonly used immunosuppressive drugs and their impact on the cardiovascular system. The adverse effect of immunosuppressive drugs is associated with toxicity within the cardiovascular system, which may be a problem in the clinical management of patients after transplantation. Immunosuppressants act on the cardiovascular system in a variety of ways, including fibrosis and myocardial remodeling, endothelium disfunction, hypertension, atherosclerosis, dyslipidemia or hyperglycaemia, metabolic syndrome, and hyperuricemia. The use of multidrug protocols makes it possible to develop regimens that can reduce the incidence of cardiovascular events. A better understanding of their mechanism of action and the range of complications could enable physicians to select the appropriate therapy for a given patient, as well as to reduce complications and prolong life.

In-situ preparation of norepinephrine-functionalized silver nanoparticles and application for colorimetric detection of tacrolimus in plasma samples

Tacrolimus (Tac) is a well-documented immunosuppressive agent for the prevention of graft-vs-host diseases in several types of organ transplants. The narrow therapeutic window and the individual-variable pharmacokinetics of Tac demonstrate the importance of regular therapeutic drug monitoring (TDM) as an imperative concept for its oral medication regimens. A simple, one-step, selective, and sensitive colorimetric platform is fabricated for the determination of Tac by surface modification of the silver nanoparticles (AgNPs) via norepinephrine (NE) molecules. The attachment of NE and Tac induces the aggregation of the AgNPs, which is observed by color distinction (yellow to brown) and a noteworthy shifting of the absorption peak in the visible region. The fabricated nanoprobe can detect Tac concentrations in plasma samples in two linear ranges from 2 ng/mL to 70 ng/mL and 70 ng/mL to 1000 ng/mL with R2 > 0.99. The limit of detection (LOD) was calculated as low as 0.1 ng/mL. The developed method was applied for the determination of Tac in patient's plasma samples under Tac medication therapy.

Immune cells and immune cell-targeted therapy in chronic pancreatitis

In recent years, studies have attempted to understand the immune cells and mechanisms underlying the pathogenesis of chronic pancreatitis (CP) by constructing a model of CP. Based on these studies, the innate immune response is a key factor in disease pathogenesis and inflammation severity. Novel mechanisms of crosstalk between immune and non-immune pancreatic cells, such as pancreatic stellate cells (PSC), have also been explored. Immune cells, immune responses, and signaling pathways in CP are important factors in the development and progression of pancreatitis. Based on these mechanisms, targeted therapy may provide a feasible scheme to stop or reverse the progression of the disease in the future and provide a new direction for the treatment of CP. This review summarizes the recent advances in research on immune mechanisms in CP and the new advances in treatment based on these mechanisms.

Automation of tacrolimus measurement on volumetric absorptive microsampling devices by tandem mass spectrometry

Aims: An automated method for the measurement of blood tacrolimus on volumetric absorptive microsampling (VAMS) devices was developed. Materials & methods: VAMS devices prepared by the automated method were compared with those prepared by the existing manual method (n = 284; mean concentration: 8.0 μg/l; range: 0.6-18.1). Results: The performance of both methods was comparable. Passing-Bablok regression demonstrated an acceptable correlation (y = -0.449 + 1.06x). Bland-Altman analysis demonstrated acceptable agreement (mean bias: -0.007 μg/l; standard deviation: 1.536). Automation reduced operator touch time by 40 min (48-sample batch). Conclusion: Automated preparation of VAMS devices reduced touch time and improved process consistency, facilitating high-throughput testing and transformation of existing laboratory workflows. Automation did not improve precision for VAMS devices but did so for liquid blood samples.

Ultrasensitive Sandwich-Type SERS-Biosensor-Based Dual Plasmonic Superstructure for Detection of Tacrolimus in Patients

Tacrolimus (FK506) is widely used in the prevention of organ transplant rejection and the treatment of autoimmune diseases, but it is difficult to detect within the low and narrow concentration range in practical clinical fields. A magnetic plasmonic superstructure-targets-plasmonic superstructure-based sandwich-type SERS biosensor is presented here to ultrasensitively detect FK506 in the blood of organ transplant patients. The spiky Fe₃O₄@SiO₂@Ag flower magnetic superstructure and hollow Ag@Au superstructure enhanced the SERS signals by providing rich sharp tips, cavities, and abundant hot spot gaps. And the magnetic feature makes it easy to concentrate and separate the biological target. Using the designed sandwich-type SERS biosensor, FK506 could be detected within a range of 0.5-20 ng/mL with a detection limit of 0.33 ng/mL. All results indicated that the sandwich-type SERS biosensor has good stability, sensitivity, and anti-interference properties. It is noteworthy that this allowed us to successfully analyze FK506 in the blood of transplant patients, which is in strong agreement with the clinical results. Consequently, the attractive sandwich-type SERS biosensor can be used for the detection of FK506 in real samples, which is promising for clinical diagnosis.

Validation of a dried blood spot method to measure tacrolimus concentrations in small volumes of mouse blood

Background: The small blood volume of mice complicates tacrolimus pharmacokinetic studies in these animals. Here we explored dried blood spot (DBS) as a novel method to measure tacrolimus blood concentrations in mice. DBS samples were collected from three sampling sites (cheek, tail and heart) and compared with heart whole blood samples measured via LC-MS/MS. Results: Tacrolimus concentrations in the whole blood samples ranged from 2.56 to 27.64 μg/l. DBS of cheek vein blood was the most reliable sampling site, with a mean bias of 0.15 μg/l (95% CI: -4.20 to 4.50). Conclusion: The DBS cheek method can be used for serial monitoring of tacrolimus blood concentrations in mice, offering an animal-friendly method for tacrolimus pharmacokinetic studies in mice.

Immunosuppressive Drugs

Immunosuppressant is a class of medicines that inhibit or decrease the intensity of the immune response in the body. Most of these medications are used to allow the body less likely to resist a transplanted organ. In solid organ transplantation, immunosuppressive agents are needed for the activation of early-stage immunosuppression, the management of late-stage immunosuppression or for the maintenance of organ rejection. The emergence of novel agents and improvements in immunosuppression regimens after transplantation are significant factors leading to this progress. However, these drugs also increase the risk of infection, cancers and specific adverse side effects specific to each agent in patients particularly in pregnant women and fertility issues. Corona virus disease being hot topic of debate is has given positive outcome to immunosuppressive drugs however need more attention in future. Transplant centers across the world utilize multiple immunosuppression protocols; nevertheless, each patient can require an individually formulated immunosuppression regimen to manage the advantages and possible damage of treatment thus eliminating the likelihood of their primary disease recurrence.

A new paper-based biosensor for therapeutic drug monitoring

Tacrolimus is one of the most effective and prevalent drugs used to combat vascularized composite allotransplantation rejection. We have fabricated a rapid and easy-to-use six-layer paper based microfluidic device using the principles of competitive immunoassays and vertical flow microfluidics for colorimetric detection of tacrolimus in a small volume of blood.

The CYP3A5 and ABCB1 Gene Polymorphisms in Kidney Transplant Patients and Establishment of Initial Daily Tacrolimus Dosing Formula

BACKGROUND

Tacrolimus is an immunosuppressive drug used to prevent organ rejections. Many factors could influence blood concentration of tacrolimus.

OBJECTIVE

To detect genotypes of cytochrome P450 3A5 (CYP3A5) and ABCB1 in kidney transplant patients and establish initial daily tacrolimus dosing formula based on genotypes of CYP3A5 and ABCB1 and patients' clinical parameters.

METHODS

Sequence specific primer polymerase chain reaction (PCR) and PCR restriction fragment length polymorphism were used to detect genotypes of CYP3A5 and ABCB1. The blood cell, procalcitonin, C-reactive protein, height, weight, age, gender and other clinical parameters were recorded. Multiple linear regression analysis and Pearson correlation analysis were used to conduct date analysis.

RESULTS

102 cases were enrolled in cohort 1, and there were 10 cases of CYP3A5 *1/*1 (9.8%), 28 cases of CYP3A5 *1/*3 (27.5%), and 64 cases of CYP3A5 *3/*3 (62.7%). The distributions of ABCB1 C3435T genotype were CC 36 (35.3%), CT 52 (51.0%), and TT 14 (13.7%). The distributions of ABCB1 G2677T/A genotype were GG 39 (38.2%), GT 40 (39.2%), and TT 23 (22.5%). The formula was 7.499 + (0.053 × Weight) - (0.029 × Hemoglobin concentration) - (1.045 × CYP3A5 genotype) (CYP3A5 genotype: *1/*1 type inputs 0, *1/*3 type inputs 1, *3/*3 type inputs 2). The predicted doses from the established formula had a significant correlation (r = 0.605) with actual clinical doses (P < 0.05).

CONCLUSION AND RELEVANCE

Hemoglobin concentration, weight, and CYP3A5 genotype should be considered using tacrolimus. The initial daily tacrolimus dosing formula established can make a good prediction.

Quantitation of Tacrolimus in Human Whole Blood Samples Using the MITRA Microsampling Device

BACKGROUND

The calcineurin inhibitor tacrolimus is a narrow therapeutic index medication, which requires therapeutic drug monitoring to optimize dose on the basis of systemic exposure. MITRA microsampling offers a minimally invasive approach for the collection of capillary blood samples from a fingerprick as an alternative to conventional venous blood sampling for quantitation of tacrolimus concentrations.

METHODS

A bioanalytical method for the quantitation of tacrolimus in human whole blood samples collected on MITRA tips was developed, using liquid-liquid extraction followed by liquid chromatography with tandem mass spectrometry detection. Validation experiments were performed according to the current Food and Drug Administration and European Medicines Agency guidelines on validation of bioanalytical methods. Validation criteria included assay specificity and sensitivity, interference, carryover, accuracy, precision, dilution integrity, matrix effect, extraction recovery, effect of hematocrit and hyperlipidemia, and stability.

RESULTS

All assay validation results were within the required acceptance criteria, indicating a precise and accurate tacrolimus quantitation method. The validated assay range was 1.00-50.0 ng/mL. No interference, carryover or matrix effect was observed. Extraction recovery was acceptable across the assay range. Samples were stable for up to 96 days at -20°C and 20°C, and 28 days at 40°C. Hematocrit, hyperlipidemia, and lot-to-lot differences in the nominal absorption volume of the 10-μL MITRA tips were shown not to influence tacrolimus quantitation by this assay method.

CONCLUSIONS

The bioanalytical method validated in this study is appropriate and practical for the quantitation of tacrolimus in human whole blood samples collected using the MITRA microsampling device.

Validation of a Capillary Dry Blood Sample MITRA-Based Assay for the Quantitative Determination of Systemic Tacrolimus Concentrations in Transplant Recipients

BACKGROUND

Tacrolimus is a narrow therapeutic index medication, which requires therapeutic drug monitoring to optimize dosing based on systemic exposure. MITRA microsampling offers a convenient, minimally invasive approach for the collection of capillary blood samples from a finger prick versus conventional venous blood sampling for quantitation of tacrolimus blood concentrations. However, the suitability of MITRA microsampling for the determination of tacrolimus concentrations requires assessment in clinical settings.

METHODS

Paired venous (2 mL) and capillary (10 μL) blood samples were collected pre-tacrolimus dose and 1 and 3 hours postdose during routine outpatient visits from stable adult liver or kidney transplant patients receiving prolonged-release tacrolimus. Tacrolimus concentrations were determined by liquid chromatography-tandem mass spectrometry, and the concentrations obtained by the 2 sampling methods were compared by linear regression and Bland-Altman agreement analyses.

RESULTS

Samples were available for 82 transplant recipients (kidney, n = 41; liver, n = 41). A high correlation was observed between tacrolimus concentrations in capillary and venous blood samples (Pearson correlation coefficient, 0.97; Lin concordance coefficient, 0.87; slope of the fitted line, >1.0). Tacrolimus concentrations in capillary samples were 22.5% higher on average than in the corresponding venous blood samples (95% limits of agreement, 0.5%-44.6%). Similar results were observed in both transplant subgroups.

CONCLUSIONS

MITRA finger prick sampling provides a convenient alternative to venipuncture for therapeutic drug monitoring in transplant recipients maintained on prolonged-release tacrolimus. When using the finger prick MITRA method, the positive bias in tacrolimus concentrations observed with this technique, when compared with venipuncture, needs to be taken into consideration.

Network pharmacology-based analysis of the role of tacrolimus in liver transplantation

Background

Tacrolimus is a powerful immunosuppressant and has been widely used in organ transplantation. In order to further explore the role of tacrolimus in liver transplantation, we conducted network pharmacology analysis.

Methods

GSE100155 was obtained from the GEO database, and the DEGs of liver transplantation were analyzed. The 2D structure of tacrolimus was obtained from the National Library of Medicine, and the pharmacophore model of tacrolimus was predicted using the online tool pharmmapper. Then a network of tacrolimus and target genes was constructed through network pharmacology, and visualization and GO enrichment analysis was performed through Cytoscape. In addition, we also analyzed the correlation between key genes and immune infiltrating cells. The data of GSE84908 was used to verify the changes of key gene expression levels after tacrolimus treatment.

Results

The results of network pharmacological analysis showed that tacrolimus had 43 target genes, and the GO enrichment results showed many potential functions. Further analysis found that there were 5 key target genes in DEGs, and these 5 genes were significantly down-regulated in liver transplant patients. Another important finding was that 5 genes were significantly related to some immune infiltrating cells. The results of the GSE84908 data analysis showed that after tacrolimus treatment, the expression of DAAM1 was significantly increased (p = 0.015).

Conclusion

Tacrolimus may inhibit the human immune response by affecting the expression of DAAM1 in liver transplant patients.

Tacrolimus, a rapamycin target protein inhibitor, exerts anti-cystic echinococcosis effects both in vitro and in vivo

In view of a growing need for new treatment options for human cystic echinococcosis (CE), we aimed to investigate the efficacy of mTOR pathway inhibitors against CE in vitro and in vivo. Among the seven mTOR inhibitors evaluated, tacrolimus (TAC) showed significant dose- and time-dependent killing of cultured protoscoleces and cysts in vitro. Notably, the oral administration of TAC (4 mg/kg/day) to CE mice model highly effectively reduced both the weight and number of parasitic cysts. Transmission electron microscopy revealed that TAC destroys the ultrastructure of cysts, both in vitro and in vivo. Furthermore, TAC had no significant effect on blood glucose, body weight, liver, or kidney functions in mice. We further observed that the ATP levels and glucose content of cysts reduced upon TAC treatment, indicating that inhibiting mTORC1 activity possibly affects glucose metabolism in the cysts of mice. Based on our experimental data, TAC emerged as a promising anti-cyst drug that efficiently inhibits the growth of cysts.

[Adverse reactions of drugs specifically used for treatment of SARS-CoV-2 infection]

Currently, there is no treatment approved for COVID-19. Numerous drugs are being used in an empirical manner according to experience and availability. Studies demonstrating their efficacy and safety are still to be published. Thus, it is of vital importance for healthcare workers to be well informed and updated regarding possible immunological and non-immunological adverse effects regarding such treatments. In this narrative revision, the rationale use of these treatments in the SARS-CoV-2 infection is emphasized as well as their most frequently described adverse drug reactions. Drugs that are being essayed to counteract both clinical phases that are thought to take place in the severe stage of this disease are included; an initial phase where a viral infection prevails and a second phase where an inflammatory response takes over. Adverse reactions registered in the Pharmacovigilance Program of our hospital before the onset of this pandemic have also been included.

Adverse reactions of drugs specifically used for treatment of SARS-CoV-2 infection

Currently, there is no treatment approved for COVID-19. Numerous drugs are being used in an empirical manner according to experience and availability. Studies demonstrating their efficacy and safety are still to be published. Thus, it is of vital importance for healthcare workers to be well informed and updated regarding possible immunological and non-immunological adverse effects regarding such treatments. In this narrative revision, the rationale use of these treatments in the SARS-CoV-2 infection is emphasized as well as their most frequently described adverse drug reactions.

Drugs that are being essayed to counteract both clinical phases that are thought to take place in the severe stage of this disease are included; an initial phase where a viral infection prevails and a second phase where an inflammatory response takes over. Adverse reactions registered in the Pharmacovigilance Program of our hospital before the onset of this pandemic have also been included.

Variation in Tacrolimus Trough Concentrations in Liver Transplant Patients Undergoing Endoscopic Retrograde Cholangiopancreatography: A Retrospective, Observational Study

Objective

High variabilities in tacrolimus (TAC) exposure are still problems that confuse physicians. TAC trough levels (TAC C_min) fluctuated considerably after endoscopic retrograde cholangiopancreatography (ERCP) treatment in several liver transplant (LT) patients. We aimed to investigate the variation regularity of TAC C_min post-ERCP and related factors.

Methods

This study was a retrospective, observational study conducted at the First Affiliated Hospital of Zhejiang University in China. From October 2017 to January 2019, 26 LT patients that received ERCP were included (73 TAC C_min measures). The absolute difference and the variation extent in TAC C_min pre- and post-ERCP were analyzed. Patients were divided into mild and obvious variation groups, and the differences were compared.

Results

The TAC C_min in LT patients significantly increased in the first three days post-ERCP (p<0.05) and increased by more than 20% in 18 out of 26 (69.2%) patients. The mean extent of variation in TAC C_min was 45.1% (95% confidence interval [CI]: 28.3–81.3%) and 31.4% (95% CI: 9.7–53.1%) on days 1 and 3 post-ERCP, respectively. The increasing TAC C_min gradually returned to baseline within a week (p>0.05). The daily TAC dose and total bile acid (TBA) level were significantly higher (p<0.05) in patients with obvious variation in TAC C_min. The differences in other demographics, clinical characteristics, variation in laboratory data, and serum amylase levels between the two groups were not significant.

Conclusion

The TAC C_min significantly increased in LT patients during the first three days after ERCP, and the level returned to baseline within a week. The daily TAC dose and TBA levels may be related to this increase. Frequent drug concentration monitoring should be executed in the early phase post-ERCP, especially in patients with related factors.

Engineering Programmed Death Ligand-1/Cytotoxic T-Lymphocyte-Associated Antigen-4 Dual-Targeting Nanovesicles for Immunosuppressive Therapy in Transplantation

T cell activation by immune allorecognition is a major contributing factor toward the triggering of organ rejection. Immunosuppressive drugs have to be taken after organ transplantation, but long-term use of these drugs increases the risks of infection and other serious disorders. Here, we showed dysregulation of programmed cell death-ligand 1/programmed cell death 1 (PD-L1/PD-1) and cytotoxic T-lymphocyte-associated protein 4/cluster of differentiation 80 (CTLA-4/CD80) in the spleen of two organ transplantation models. Using a bioengineering approach, cellular exosome-like nanovesicles (NVs) displaying PD-L1/CTLA-4 dual-targeting cargos were designed, and their specificity to bind their ligands PD-1 and CD80 on T cell and dendritic cell surfaces was confirmed. These NVs consequently enhanced PD-L1/PD-1 and CTLA-4/CD80 immune inhibitory pathways, two key immune checkpoints to co-inhibit T cell activation and maintain peripheral tolerance. It was also confirmed that PD-L1/CTLA-4 NVs led to the reduction of T cell activation and proliferation in vitro and in vivo. Finally, it was demonstrated that PD-L1/CTLA-4 NVs reduced density of CD8⁺ T cells and cytokine production, enriched regulatory T cells, and prolonged the survival of mouse skin and heart grafts. Taken together, these data supported the idea that PD-L1/CTLA-4 dual-targeting NVs exert immune inhibitory effects and may be used as a prospective immunosuppressant in organ transplantation.

High Intrapatient Variability in Tacrolimus Exposure Is Not Associated With Immune-mediated Graft Injury After Liver Transplantation

BACKGROUND

A high intrapatient variability (IPV) in tacrolimus exposure is associated with impaired long-term clinical outcome after kidney transplantation. It remains to be determined if this is equally detrimental for liver transplant recipients. The objective of this study was to investigate the association between IPV in tacrolimus exposure and immune-mediated graft injury after liver transplantation.

METHODS

For 326 liver transplant recipients, transplanted between 2000 and 2015, tacrolimus IPV was calculated from at least 5 tacrolimus trough samples obtained between months 6 and 18 after liver transplantation and expressed as the coefficient of variation. Primary composite endpoint consisted of immune-mediated graft injury (chronic rejection, biopsy proven, and suspected late acute rejection) after month 6. Secondary outcomes were the association between tacrolimus IPV on (1) loss of renal function per year of follow-up and (2) cytomegalovirus viremia after month 6.

RESULTS

Of the 326 included liver transplant recipients, 70 patients (21.5%) reached the primary endpoint. Median tacrolimus coefficient of variation was 28%. There was no significant difference in reaching the primary composite endpoint between the low- and high-IPV groups (P = 0.068). Model for End-Stage Liver Disease score pretransplantation and the number of acute rejections were identified as independent predictors for immune-mediated graft injury (P = 0.049 and 0.016). A higher IPV in combination with a low kidney function at baseline (estimated glomerular filtration rate < 40 mL/min) was associated with greater loss of renal function per year of follow-up (P = 0.007). Tacrolimus variability was not associated with late cytomegalovirus viremia.

CONCLUSIONS

High IPV in tacrolimus exposure beyond month 6 postliver transplantation was not associated with immune-mediated graft injury.

Tacrolimus therapeutic efficacy in post-liver transplant patients with Cytochrome P450 3A5 (CYP3A5) genetic polymorphisms

Genetic polymorphisms of CYP3A5 have been pointed out as factors that influenciates tacrolimus immunosuppressive efficacy in post liver transplant patients. This study aims to review the literature on the influence of cytochrome P450 3A5 (CYP3A5) genetic polymorphisms of tacrolimus in post-liver transplant patients. This study is a literature review. A combination of the descriptors "tacrolimus", "liver transplant", "cytochrome P-450 CYP3A inhibitors" and "genetic polymorphism" were used in the databases PubMed, Cochrane Library, Scopus and Scielo, being evaluated only studies between 2009 and 2019 in English, Portuguese or Spanish. A total of six studies, each from a different population were summarized. Initially, the pharmacological aspects of tacrolimus were discussed, including details on its pharmacodynamics, pharmacokinetics and toxicity After that, we analyzed the studies that correlates CYP3A5 genetic polymorphisms and tacrolimus efficacy, including the ethnical specifications and the general limittions of the studies. The CYP3A5 polymorphisms have pointed to alterations in the metabolism of tacrolimus according to the ethnic and populational genotype, specially the *1 and *3*3 alleles, reflecting in the need for dose adjustment and also in post liver transplant rejection.

Effects of Different Tacrolimus Doses on Adipose-Derived Stem Cells

OBJECTIVES

Tacrolimus is currently one of the most commonly used immunosuppressant agents to prevent rejection in organ transplant. Although modern immunosuppressive agents have been successful, rejection cannot be completely prevented. Therefore, in organ transplant research, additional treatment methods are being investigated, with the most important one being stem cell therapy. In addition to tacrolimus therapy, stem cell therapy is now clinically applicable, with frequency of concomitant use seeming to expand in the future. In this study, the effects of tacrolimus on stem cells were investigated.

MATERIALS AND METHODS

Adipose-derived stem cells were treated with tacrolimus at different doses and time points. We analyzed the effects of changes in stem cell proliferation using MTT analysis. Sox2, Oct3/4, and Nanog protein levels were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to measure stem cell pluripotency capabilities.

RESULTS

Our observations showed that tacrolimus causes changes in stem cell proliferation and pluripotency, with changes dependent on time and dose.

CONCLUSIONS

The dose of tacrolimus and the time of application of stem cells are important in the planning of stem cell therapy in organ transplant.

Sensitive UHPLC–MS/MS method for the determination of tacrolimus in minipig whole blood

Background: Tacrolimus, a potent immunosuppressant drug widely used systemically to reduce the risk of organ rejection in transplants, has been repositioned for topical treatment of atopic dermatitis. Results & methodology: This work describes the optimization of a new method for the determination of tacrolimus in whole blood after topical administration. Sample treatment consisted of an automated procedure based on protein precipitation followed by solid-phase extraction. The present method showed good performance with quantitation limits of 10 pg ml-1 and intra- and interday precision and accuracy lower than 15 and 10%, respectively. Conclusion: A new highly sensitive UHPLC–MS/MS method has been developed enabling a better characterization of the minipig blood plasma pharmacokinetic behavior of tacrolimus after topical administration.

T Lymphocytes: A Promising Immunotherapeutic Target for Pancreatitis and Pancreatic Cancer?

Pancreatic disorders cause a broad spectrum of clinical diseases, mainly including acute and chronic pancreatitis and pancreatic cancer, and are associated with high global rates of morbidity and mortality. Unfortunately, the pathogenesis of pancreatic disease remains obscure, and there is a lack of specific treatments. T lymphocytes (T cells) play a vital role in the adaptive immune systems of multicellular organisms. During pancreatic disease development, local imbalances in T-cell subsets in inflammatory and tumor environments and the circulation have been observed. Furthermore, agents targeting T cells have been shown to reverse the natural course of pancreatic diseases. In this review, we have discussed the clinical relevance of T-cell alterations as a potential outcome predictor and the underlying mechanisms, as well as the present status of immunotherapy targeting T cells in pancreatitis and neoplasms. The breakthrough findings summarized in this review have important implications for innovative drug development and the prospective use of immunotherapy for pancreatitis and pancreatic cancer.

Inhibition of the cyclophilin A-CD147 interaction attenuates right ventricular injury and dysfunction after acute pulmonary embolism in rats

Acute pulmonary embolism (APE)-induced inflammation contributes to cardiomyocyte injury and dysfunction in the right ventricle (RV) of the heart. The interactions of cyclophilin A with its ligand extracellular matrix metalloproteinase inducer (EMMPRIN or CD147) may be involved in this inflammatory process. To this end, here we induced APE by intravenous injections of microspheres in Sprague-Dawley rats. We found that after the APE, cyclophilin A and CD147 levels increased synchronously in RV tissue following APE and peaked at 24 h. The cyclophilin A inhibitor cyclosporine A attenuated the APE-induced cyclophilin A levels, and a monoclonal antibody of CD147 (anti-CD147) abrogated the elevation of CD147 in the RV but not the increase of cyclophilin A. Importantly, treatment with cyclosporine A, anti-CD147, or both attenuated APE-induced increases in RV systolic pressure, plasma cardiac troponin-I (cTnI) concentrations, the RV/left ventricle diameter ratio, and the Tei index, measured by echocardiography 24 h after APE induction. These beneficial effects were associated with reduced RV neutrophil infiltration and prevention of matrix metalloproteinase 9 (MMP-9) and MMP-2 activation. These findings suggested that inhibiting the cyclophilin A-CD147 interaction attenuates APE-associated RV cardiomyocyte injury and dysfunction by suppressing inflammation. We further proposed that cyclophilin A and CD147 might participate in APE-induced pathological processes by partly activating the ERK1/2 kinase-nuclear factor-κB pathway. We conclude that the cyclophilin A-CD147 interaction may represent a potential therapeutic target for managing APE.