Immunosuppression trends in solid organ transplantation: The future of individualization, monitoring, and management

Steroid-tacrolimus drug-drug interaction and the effect of CYP3A genotypes

AIMS

Tacrolimus, metabolized by CYP3A4 and CYP3A5 enzymes, is susceptible to drug-drug interactions (DDI). Steroids induce CYP3A genes to increase tacrolimus clearance, but the effect is variable. We hypothesized that the extent of the steroid-tacrolimus DDI differs by CYP3A4/5 genotypes.

METHODS

Kidney transplant recipients (n = 2462) were classified by the number of loss of function alleles (LOF) (CYP3A5*3, *6 and *7 and CYP3A4*22) and steroid use at each tacrolimus trough in the first 6 months post-transplant. A population pharmacokinetic analysis was performed by nonlinear mixed-effect modelling (NONMEM) and stepwise covariate modelling to define significant covariates affecting tacrolimus clearance. A stochastic simulation was performed and translated into a Shiny application with the mrgsolve and Shiny packages in R.

RESULTS

Steroids were associated with modestly higher (3%-11.8%) tacrolimus clearance. Patients with 0-LOF alleles receiving steroids showed the greatest increase (11.8%) in clearance compared to no steroids, whereas those with 2-LOFs had a negligible increase (2.6%) in the presence of steroids. Steroid use increased tacrolimus clearance by 5% and 10.3% in patients with 1-LOF and 3/4-LOFs, respectively.

CONCLUSIONS

Steroids increase the clearance of tacrolimus but vary slightly by CYP3A genotype. This is important in individuals of African ancestry who are more likely to carry no LOF alleles, may more commonly receive steroid treatment, and will need higher tacrolimus doses.

Pharmacodynamic Effect of mTOR Inhibition-based Immunosuppressive Therapy on T- and B-cell Subsets After Renal Transplantation

Background

The mammalian target of rapamycin inhibitor (mTORi) therapy after kidney transplantation is solely monitored pharmacokinetically, not necessarily reflecting PI3K-Akt-mTOR pathway blockade efficacy leading to potential under-or overimmunosuppression.

Methods

In this cross-sectional study, phosphoflow cytometry was used to determine the efficacy of mTOR inhibition in peripheral T- and B-lymphocyte subsets by assessing p70S6 kinase (p70S6K) phosphorylation in renal transplant recipients upon treatment with a combination of either mTORi and calcineurin inhibitors (n = 18), or mTORi with mycophenolic acid (n = 9). Nine dialysis patients with end-stage renal disease and 17 healthy age-matched volunteers served as controls.

Results

mTORi treatment reduced p70S6K phosphorylation in CD4+, CD8+ T, and CD19+ B cells compared with healthy controls (HCs). Subpopulation analysis of CD4+ T cells and CD19+ B cells revealed a significant reduction of p70S6K phosphorylation in CD4+CD45RA-CD25- Th cells (P < 0.05), CD24hiCD38hi transitional B cells (P < 0.001), CD24+CD38- memory B cells (P < 0.001), and CD24intCD38int-naive B cells (P < 0.05) upon mTORi treatment, whereas CD4+CD45RA-CD25++CD127- regulatory T cells and CD24-CD38hi plasmablasts were not affected. Compared with mTORi + mycophenolic acid therapy, mTORi + calcineurin inhibitor treatment exhibited an even stronger inhibition of p70S6K phosphorylation in CD4+CD45RA-CD25- Th cells and CD8+ T cells. However, trough levels of mTORi did not correlate with p70S6K phosphorylation.

Conclusions

mTORi selectively inhibited p70S6K phosphorylation in select lymphocyte subtypes. Assessing p70S6K phosphorylation by phosphoflow cytometry may serve as an approach to understand cell subset specific effects of mTORi providing detailed pharmacodynamic information for individualizing immunosuppression.

Cancer risk in people living with HIV and solid organ transplant recipients: a systematic review and meta-analysis

BACKGROUND

Systematic evaluations of cancer risk in people living with HIV or AIDS (PLHIV) and solid organ transplant recipients provide unique insights into the role of the immune system in cancer development. In this systematic review and meta-analysis, we expand previous analyses of cancer risk for these two immunocompromised populations.

METHODS

We considered studies published in English and listed on PubMed or Embase up to July 1, 2022. Studies were eligible for inclusion if they used population-based registries and compared cancer incidence in PLHIV or solid organ transplant recipients with the general population in the same geographical area. We extracted the number of observed site-specific cancers and expected cases and calculated meta-standardised incidence ratios for cancer within PLHIV and solid organ transplant recipients. In solid organ transplant recipients meta-standardised incidence ratios were compared by organ type. This project is registered on PROSPERO, CRD42022366679.

FINDINGS

46 studies in PLHIV and 67 in solid organ transplant recipients were included in the analysis. Meta-standardised incidence ratios for cancers associated with human papillomavirus were increased in both populations; the highest meta-standardised incidence ratio in PLHIV was anal cancer (37·28 [95% CI 23·65-58·75], I2=97·4%), and in solid organ transplant recipients was cutaneous squamous cell carcinoma (45·87 [31·70-66·38], I2=99·0%). Meta-standardised incidence ratios were significantly increased for most non-HPV viral-infection-related cancers in both populations; the highest standard incidence ratios were for Kaposi sarcoma (PLHIV: 801·52 [95% CI 200·25-3208·13], I2=100·0%; solid organ transplant recipients: 47·31 [23·09-96·95], I2=87·7%) and non-Hodgkin lymphoma (32·53 [19·64-53·87], I2=99·8%; 10·24 [8·48-12·35], I2=94·9%). Eight types of cancer with no known viral cause showed an increased risk in solid organ transplant recipients only; no cancer type showed increased risk in PLHIV only.

INTERPRETATION

Cancer risk was increased for a range of infection-related cancers in both PLHIV and solid organ transplant recipients, but divergent results in these and other cancers have emerged. The cancer risk patterns probably reflect variances in the degree of impaired immunity, exposure to carcinogenic viruses, and perhaps exposure to carcinogenic immunosuppressive agents.

FUNDING

US National Cancer Institute, National Institutes of Health.

Evolving trends in immunosuppression use and cytomegalovirus infection risk over the past decade in kidney transplantation

BACKGROUND

The goal was to determine trends in immunosuppression use and its impact on cytomegalovirus (CMV) outcomes over the past 10 years.

METHODS

This was a single-center longitudinal cohort study of adult kidney recipients transplanted between Jan 2012 and June 2021. Baseline and follow-up data were gathered via chart abstraction and analyzed using univariate and multivariate analyses.

RESULTS

Of 2392 kidney transplants conducted, 131 patients did not meet inclusion criteria. The mean age was 52 years, 41% were female, 57% were black, and 19% were CMV high-risk. The use of rabbit anti-thymocyte globulin (RATG) induction (odds ratio [OR] 1.6, 1.3-2.1), tacrolimus (FK) level >8 ng/mL (OR 1.1, 1.09-1.11), CMV D+/R- rates (OR 1.06, 1.02-1.10), white blood cell count <3000 (OR 1.22, 1.18-1.26) and valganciclovir prophylaxis (OR 1.7, 1.6-1.9) have significantly increased over the past 10 years.  Rejection rates (OR 0.86, 0.82-0.91) and BK viremia >2000 (OR 0.91, 0.91-0.98) have decreased. RATG induction (adjusted hazard ratio [aHR] 1.35, 1.2-1.5), FK >8 ng/mL (aHR 3.5, 3.2-3.9), Belatacept conversion (aHR 2.5, 2.1-3.1), and rejection (aHR 1.8, 1.6-2.0) were significant risk factors for developing CMV infection, while mycophenolate mofetil <1500 mg (aHR 0.52, 0.47-0.59), mammalian target of rapamycin inhibitor (mTORi) conversion (0.77, 0.56-0.89), cyclosporine-A conversion (aHR 0.68, 0.56-0.84) were associated with lower risk of CMV infection.

CONCLUSION

Increasing use of potent immunosuppression coupled with higher CMV D+/R- F rates may be driving higher rates of CMV infection. Cyclosporine and mTORi conversion appears to be protective against CMV.  A more individualized immunosuppression regimen based on infection risk merits consideration.

Outcomes in solid organ transplant recipients with a pretransplant diagnosis of melanoma

Melanoma causes significant morbidity in solid organ transplant recipients (SOTRs). Melanomas diagnosed before transplantation can recur with intensive immunosuppression, but outcomes have not been well studied. We evaluated 901 non-Hispanic White SOTRs with a pretransplant melanoma identified using linked transplant and cancer registry data in the United States. Most pretransplant melanomas were invasive (60.7%), and the median time from diagnosis to transplantation was 5.1 years. After transplantation, 41 SOTRs developed a new invasive melanoma, corresponding to 9-fold increased risk compared with the general population (standardized incidence ratio, 9.2; 95% confidence interval [CI], 6.6-12). Twenty-two SOTRs died from melanoma after transplantation, corresponding to 52-fold increased risk (standardized mortality ratio, 52; 95% CI, 33-79). Risk factors for posttransplant melanoma included age at transplantation (adjusted hazard ratio [HR], 2.86; 95% CI, 1.24-6.60; for age 55+ vs <55 years) and maintenance immunosuppression with cyclosporine/azathioprine (adjusted HR, 2.53; 95% CI, 1.08-5.90). Melanoma mortality was strongly elevated after a posttransplant melanoma diagnosis (HR, 35.6; 95% CI, 14.0-90.4; adjusted for cyclosporine/azathioprine maintenance therapy and calendar year of transplantation). In conclusion, SOTRs with a pretransplant melanoma are at risk of adverse melanoma-related outcomes after transplantation. These findings support thorough dermatologic evaluation prior to transplantation and frequent posttransplant surveillance.

New insights in immunomodulation for intestinal transplantation

Tolerance is the Holy Grail of solid organ transplantation (SOT) and remains its primary challenge since its inception. In this topic, the seminal contributions of Thomas Starzl at Pittsburgh University outlined foundational principles of graft acceptance and tolerance, with chimerism emerging as a pivotal factor. Immunologically, intestinal transplantation (ITx) poses a unique hurdle due to the inherent characteristics and functions of the small bowel, resulting in increased immunogenicity. This necessitates heavy immunosuppression (IS) while IS drugs side effects cause significant morbidity. In addition, current IS therapies fall short of inducing clinical tolerance and their discontinuation has been proven unattainable in most cases. This underscores the unfulfilled need for immunological modulation to safely reduce IS-related burdens. To address this challenge, the Leuven Immunomodulatory Protocol (LIP), introduced in 2000, incorporates various pro-tolerogenic interventions in both the donor to the recipient, with the aim of facilitating graft acceptance and improving outcome. This review seeks to provide an overview of the current understanding of tolerance in ITx and outline recent advances in this domain.

Long-term outcomes of two-dose alemtuzumab induction in pediatric kidney transplantation

BACKGROUND

Alemtuzumab is a lymphocyte depleting agent used for induction in kidney transplant, but long-term information on its use in pediatric recipients remains sparse.

METHODS

We performed a single-center retrospective cohort study of 57 pediatric kidney transplant recipients receiving alemtuzumab 20 mg/m2/dose ×2 doses for induction immunosuppression. All patients underwent surveillance biopsies, and 91.3% underwent steroid withdrawal by day 4 post-transplant. Outcomes of interest included graft survival, development of donor specific antibodies (DSA), incidence of viremia and PTLD, and duration of lymphopenia.

RESULTS

Median follow-up time was 7.9 years (IQR 5-13.6 years). Median graft survival was 16.5 years (95% CI 11.6-unknown). DSA developed in 36.5% at a median of 944 days (IQR 252-2113 days). Incidences of BK polyomavirus DNAemia (BKPyV-DNAemia), CMV DNAemia, and EBV DNAemia were 38.6%, 22.8%, and 14%, respectively; one patient developed PTLD at 13.3 years post-transplant. Median duration of lymphopenia was 365 days (IQR 168-713 days); 19.3% of patients remained lymphopenic at 3 years post-transplant. There was no association between duration of lymphopenia and graft survival, rejection, DSA detection, or viremia.

CONCLUSIONS

A two-dose alemtuzumab induction protocol can have excellent outcomes with a steroid-free maintenance immunosuppression regimen. More comprehensive, multicenter, comparative studies of pediatric kidney transplant are needed to improve long-term outcomes.

Effect of Short Peptides of Pregnancy-Specific β1-Glycoprotein on Differentiation of Human Regulatory T Cells In Vitro and on Their Cytokine Profile

Pregnancy-specific β1-glycoprotein (PSG), one of the most important proteins of pregnancy, has a pronounced immunosuppressive effect. Short peptides of PSG, the so-called SLiMs (short linear motifs), are promising molecules for mild immunosuppression. We studied in vitro effect of short PSG peptides (YACS, YQCE, YVCS, and YECE) on differentiation and cytokine profile of human T-regulatory lymphocytes (Treg). T helpers isolated from the peripheral blood and polarized into the Treg phenotype with a T-cell activator (anti-CD2/3/28) and the cytokines IL-2 and transforming grown factor β (TGFβ) were used. PSG peptides were shown to have no direct modulatory effect on Treg differentiation in a culture of CD4+ cells polarized to the Treg phenotype. At the same time, PSG peptides had no effect on the viability and number of CD4+ cells in the in vitro culture. PSG peptides also had no effect on the levels of TNFα, IL-8, IL-2, macrophage inflammatory protein 1β, IL-17, IL-10, IL-6, granulocyte-macrophage CSF, monocyte chemoattractant protein 1, IL-13, IL-5, IL-7, IL-12(p70), IL-1β, granulocyte CSF, IL-4, but decreased IFNγ levels. The observed ability of the YQCE peptide to reduce the production of this proinflammatory Th1 cytokine by T helper cells can be interpreted as a positive effect. Our findings can be used for further development of safe peptide drugs based on SLiMs sequences.

Incisional hernias post renal transplant: a systematic review and meta-analysis

PURPOSE

Incisional hernia (IH) post renal transplant (RT) is relatively uncommon and can be challenging to manage clinically due to the presence of the kidney graft and patient immunosuppression. This systematic review and meta-analysis synthesises the current literature in relation to IH rates, risk factors and outcomes post RT.

METHODS

PubMed, EMBASE, and Cochrane Central Registry of Controlled Trials (CENTRAL) were searched up to July 2023. The most up to date Preferred Reporting Items for Systematic Reviews and Meta Analyses guidelines were followed. Pertinent clinical information was synthesised. A meta-analysis of the pooled proportions of IH rates, the rates of patients requiring surgical repair and the rates of recurrence post RT are reported.

RESULTS

Twenty studies comprising 16,018 patients were included in this analysis. The pooled rate of IH occurrence post RT was 4% (CI 3-5%). The pooled rate of IH repair post RT was 61% (CI 14-100%). The pooled rate of IH recurrence after repair was 16% (CI 9-23%). Risk factors identified for IH development post RT are BMI, immunosuppression, age, smoking, incision type, reoperation, concurrent abdominal wall hernia, lymphocele formation and pulmonary disease.

CONCLUSIONS

IH post RT is uncommon and the majority of IH post RT are repaired surgically on an elective basis.

Deceased-Donor Kidney Transplant Outcome Prediction Using Artificial Intelligence to Aid Decision-Making in Kidney Allocation

In kidney transplantation, pairing recipients with the highest longevity with low-risk allografts to optimize graft-donor survival is a complex challenge. Current risk prediction models exhibit limited discriminative and calibration capabilities and have not been compared to modern decision-assisting tools. We aimed to develop a highly accurate risk-stratification index using artificial intelligence (AI) techniques. Using data from the UNOS database (156,749 deceased kidney transplants, 2007-2021), we randomly divided transplants into training (80%) and validation (20%) sets. The primary measure was death-censored graft survival. Four machine learning models were assessed for calibration (integrated Brier score [IBS]) and discrimination (time-dependent concordance [CTD] index), compared with existing models. We conducted decision curve analysis and external validation using UK Transplant data. The Deep Cox mixture model showed the best discriminative performance (area under the curve [AUC] = 0.66, 0.67, and 0.68 at 6, 9, and 12 years post-transplant), with CTD at 0.66. Calibration was adequate (IBS = 0.12), while the kidney donor profile index (KDPI) model had lower CTD (0.59) and AUC (0.60). AI-based D-TOP outperformed the KDPI in evaluating transplant pairs based on graft survival, potentially enhancing deceased donor selection. Advanced computing is poised to influence kidney allocation schemes.

Immunoprotection of cellular transplants for autoimmune type 1 diabetes through local drug delivery

Type 1 diabetes mellitus (T1DM) is an autoimmune condition that results in the destruction of insulin-secreting β cells of the islets of Langerhans. Allogeneic islet transplantation could be a successful treatment for T1DM; however, it is limited by the need for effective, permanent immunosuppression to prevent graft rejection. Upon transplantation, islets are rejected through non-specific, alloantigen specific, and recurring autoimmune pathways. Immunosuppressive agents used for islet transplantation are generally successful in inhibiting alloantigen rejection, but they are suboptimal in hindering non-specific and autoimmune pathways. In this review, we summarize the challenges with cellular immunological rejection and therapeutics used for islet transplantation. We highlight agents that target these three immune rejection pathways and how to package them for controlled, local delivery via biomaterials. Exploring macro-, micro-, and nano-scale immunomodulatory biomaterial platforms, we summarize their advantages, challenges, and future directions. We hypothesize that understanding their key features will help identify effective platforms to prevent islet graft rejection. Outcomes can further be translated to other cellular therapies beyond T1DM.

Prospective observational study to validate a next-generation sequencing blood RNA signature to predict early kidney transplant rejection

The objective of this study was to validate the performance of Tutivia, a peripheral blood gene expression signature, in predicting early acute rejection (AR) post-kidney transplant. Recipients of living or deceased donor kidney transplants were enrolled in a nonrandomized, prospective, global, and observational study (NCT04727788). The main outcome was validation of the area under the curve (AUC) of Tutivia vs serum creatinine at biopsy alone, or Tutivia + serum creatinine at biopsy. Of the 151 kidney transplant recipients, the mean cohort age was 53 years old, and 64% were male. There were 71% (107/151) surveillance/protocol biopsies and 29% (44/151) for-cause biopsies, with a 31% (47/151) overall rejection rate. Tutivia (AUC 0.69 [95% CI: 0.59-0.77]) and AUC of Tutivia + creatinine at biopsy (0.68 [95% CI: 0.59-0.77]) were greater than the AUC of creatinine at biopsy alone (0.51.4 [95% CI: 0.43-0.60]). Applying a model cut-off of 50 (scale 0-100) generated a high- and low-risk category for AR with a negative predictive value of 0.79 (95% CI: 0.71-0.86), a positive predictive value of 0.60 (95% CI: 0.45-0.74), and an odds ratio of 5.74 (95% CI: 2.63-12.54). Tutivia represents a validated noninvasive approach for clinicians to accurately predict early AR, beyond the current standard of care.

Immunosuppression in solid organ-transplant recipients and impact on nutrition support

A key component to nutrition support is to consider immunosuppressive agents, the interaction with nutrients, and how the side effects of the medications influence nutrition support. The immunosuppression of the solid organ-transplant recipient involves the individualized titration of multiple therapeutic agents to prevent allorecognition and, thus, rejection of the transplanted organ. Induction immunosuppression includes the agents used at the time of transplant to prevent early rejection. Maintenance immunosuppression typically consists of oral medications taken for life. Regular therapeutic monitoring of immunosuppression is necessary to balance the risk of rejection with that of infections and malignancy. In the acute-care setting, multidisciplinary collaboration, including pharmacy and nutrition, is needed to optimize the route of administration, titration, and side effects of immunosuppression. Long-term nutrition management after transplant is also vital to prevent exacerbating adverse effects of immunosuppressive therapies, including diabetes mellitus, hypertension, dyslipidemia, obesity, and bone loss. This review summarizes common immunosuppressive agents currently utilized in solid organ-transplant recipients and factors that may influence decisions on nutrition support.

Slaying the "Troll of Transplantation"-new frontiers in cytomegalovirus management: A report from the CMV International Symposium 2023

The 2023 International CMV Symposium took place in Barcelona in May 2023. During the 2-day meeting, delegates and faculty discussed the ongoing challenge of managing the risk of cytomegalovirus infection (the Troll of Transplantation) after solid organ or hematopoietic cell transplantation. Opportunities to improve outcomes of transplant recipients by applying advances in antiviral prophylaxis or pre-emptive therapy, immunotherapy, and monitoring of cell-mediated immunity to routine clinical practice were debated and relevant educational clinical cases presented. This review summarizes the presentations, cases, and discussions from the meeting and describes how further advances are needed before the Troll of Transplantation is slain.

Prevalence of Steroid-Induced Hyperglycemia in King Abdulaziz Specialist Hospital, Taif City, Saudi Arabia

Background Hyperglycemia is a common side effect of high-dose steroid therapy in hospitalized patients. Objectives To assess the prevalence of hyperglycemia among hospitalized patients receiving steroid therapy. Methods A retrospective study was conducted among 245 patients. The inclusion criteria were patients undergoing steroid therapy and admitted to a single tertiary care hospital due to medical complications or exacerbation of the diseases they were suffering from. Data encompassing patient demographics, admission, discharge dates, comorbidities, medication histories, laboratory results (including blood glucose levels), and documented corticosteroid administrations were meticulously gathered from electronic health records (EHRs). A logistic regression model analysis was done to predict the risk factors of poor glycemic control among hospitalized patients. Results The prevalence of hyperglycemia among the patients who were on steroid therapy was 34.2%. About 70.7% of the patients who required insulin at the time of admission required >17 units, and the insulin requirement was significantly higher among patients who received dexamethasone compared to other steroids (p<0.05). Older age (>65 years) was found to be independently associated with poor glycemic control (p<0.05). Conclusion The study revealed that almost one-third of patients on steroid therapy had hyperglycemia. Monitoring of patients for hyperglycemia after beginning high-dose steroid therapy should be done.

Alteration of γδ T cell subsets in non-human primates transplanted with GGTA1 gene-deficient porcine blood vessels

BACKGROUND

αGal-deficient xenografts are protected from hyperacute rejection during xenotransplantation but are still rejected more rapidly than allografts. Despite studies showing the roles of non-Gal antibodies and αβ T cells in xenograft rejection, the involvement of γδ T cells in xenograft rejection has been limitedly investigated.

METHODS

Six male cynomolgus monkeys were transplanted with porcine vessel xenografts from wild-type (n = 3) or GGTA1 knockout (n = 3) pigs. We measured the proportions and T cell receptor (TCR) repertoires of blood γδ T cells before and after xenotransplant. Grafted porcine vessel-infiltrating immune cells were visualized at the end of experiments.

RESULTS

Blood γδ T cells expanded and infiltrated into the graft vessel adventitia following xenotransplantation of α-Gal-deficient pig blood vessels. Pre- and post-transplant analysis of γδ TCR repertoire revealed a transition in δ chain usage post-transplantation, with the expansion of several clonotypes of δ1, δ3, or δ7 chains. Furthermore, the distinctions between pre- and post-transplant δ chain usages were more prominent than those observed for γ chain usages.

CONCLUSION

γδ TCR repertoire was significantly altered by xenotransplantation, suggesting the role of γδ T cells in sustained xenoreactive immune responses.

Ocular Symptoms in Kidney, Liver, and Heart Transplant Patients

OBJECTIVES

The purpose of this study was to report the ocular manifestations in kidney, liver, and heart transplant recipients.

MATERIALS AND METHODS

We reviewed the medical records of kidney, liver, and heart transplant recipients who were examined at the ophthalmology clinic of a tertiary hospital between October 2021 and October 2022. We evaluated the ocular complaints of the patients, ophthalmological examination findings, the etiology of the underlying disease, comorbidities, posttransplant duration, and the medications used. Ocular pathologies were classified as corneal, conjunctival, lens, vitreoretinal, and optic disc pathologies for the analysis.

RESULTS

Our study included 233 patients (191 kidney, 40 liver, 2 heart transplant patients). Mean age of patients was 42.94 ± 17.45 years. Among the patient group, 80.3% had at least 1 pathological ocular finding. In subgroup analysis, 12.4% of the patients had corneal pathologies, 19.3% had conjunctival pathologies, 33.0% had lens pathologies, 33.5% had vitreoretinal pathologies, and 18.9% had optic disc-related pathologies. The most common finding was dry eye, followed by cataract and vitreoretinal pathologies. The most common vitreoretinal pathology was diabetic retinopathy, followed by hypertensive retinopathy. The ocular pathology incidence in kidney and liver transplant patients was similar (P = .05). The 2 heart transplant patients did not have any ocular pathologies except refractive errors. In addition, no significant correlation was observed between posttransplant duration and ocular pathologies (P = .28).

CONCLUSIONS

Ocular findings were seen in most of the kidney and liver transplant recipients. Therefore, it is required that these patients undergo routine ocular screenings in order to facilitate early diagnosis and prompt treatment when needed.

Tacrolimus Pharmacokinetics is Associated with Gut Microbiota Diversity in Kidney Transplant Patients: Results from a Pilot Cross-Sectional Study

Clinical use of tacrolimus (TAC), an essential immunosuppressant following transplantation, is complexified by its high pharmacokinetic (PK) variability. The gut microbiota gains growing interest but limited investigations have evaluated its contribution to TAC PKs. Here, we explore the associations between the gut microbiota composition and TAC PKs. In this pilot cross-sectional study (Clinicaltrial.gov NCT04360031), we recruited 93 CYP3A5 non-expressers stabilized kidney transplant recipients. Gut microbiota composition was characterized by 16S rRNA gene sequencing, TAC PK parameters were computed, and additional demographic and medical covariates were collected. Associations between PK parameters or diabetic status and the gut microbiota composition, as reflected by α- and β-diversity metrics, were evaluated. Patients with higher TAC area under the curve AUC/(dose/kg) had higher bacterial richness, and TAC PK parameters were associated with specific bacterial taxa (e.g., Bilophila) and amplicon sequence variant (ASV; e.g., ASV 1508 and ASV 1982 (Veillonella/unclassified Sporomusaceae); ASV 664 (unclassified Oscillospiraceae)). Building a multiple linear regression model showed that ASV 1508 (co-abundant with ASV 1982) and ASV 664 explained, respectively, 16.0% and 4.6% of the interindividual variability in TAC AUC/(dose/kg) in CYP3A5 non-expresser patients, when adjusting for hematocrit and age. Anaerostipes relative abundance was decreased in patients with diabetes. Altogether, this pilot study revealed unprecedented links between the gut microbiota composition and diversity and TAC PKs in stable kidney transplant recipients. It supports the relevance of studying the gut microbiota as an important contributor to TAC PK variability. Elucidating the causal relationship will offer new perspectives to predict TAC inter- and intra-PK variability.

Liver-Targeting Nanoplatforms for the Induction of Immune Tolerance

Liver-targeting nanoparticles have emerged as a promising platform for the induction of immune tolerance by taking advantage of the liver's unique tolerogenic properties and nanoparticles' physicochemical flexibility. Such an approach provides a versatile solution to the treatment of a diversity of immunologic diseases. In this review, we begin by assessing the design parameters integral to cell-specific targeting and the tolerogenic induction of nanoplatforms engineered to target the four critical immunogenic hepatic cells, including liver sinusoidal epithelial cells (LSECs), Kupffer cells (KCs), hepatic stellate cells (HSCs), and hepatocytes. We also include an overview of multiple therapeutic strategies in which nanoparticles are being studied to treat many allergies and autoimmune disorders. Finally, we explore the challenges of using nanoparticles in this field while highlighting future avenues to expand the therapeutic utility of liver-targeting nanoparticles in autoimmune processes.

B and T Cell Responses to SARS-CoV-2 Vaccination in Kidney and Liver Transplant Recipients with and without Previous COVID-19

(1) Background: Vulnerable populations including transplant recipients are jeopardised by COVID-19. Herein, we report on B and T cell responses among liver and kidney organ recipients at our centre. (2) Methods: 23 liver and 45 kidney (14 thereof combined kidney/pancreas) transplanted patients were vaccinated with two doses of BNT162b2 followed by a booster dose of mRNA-1273 in 28 non-responders 4 months thereafter. Anti-SARS-CoV-2-Ig was measured by specific ELISA and virus neutralisation assay; T cell responses were measured by a spike protein-specific IFN-γ release assay. (3) Results: Compared to controls, B and T cell responses were weak in transplant recipients, particularly in those without prior exposure to SARS-CoV-2. Within this group, only 15% after the first and 58.3% after the second vaccination achieved seroconversion. A total of 14 out of 28 vaccination non-responders achieved a seroconversion after a third dose. Vaccination side effects were more frequent in healthy controls. The use of mycophenolate was associated with reduced anti-SARS-CoV-2-Ig production. (4) Conclusions: Our data confirm that vaccination responses are insufficient after standard vaccination in liver and kidney transplant recipients and are affected to a variable degree by specific immunosuppressants, particularly mycophenolate. Monitoring vaccination success and re-vaccinating those who are unresponsive seems prudent to achieve sufficient titres. Overall, prospective large-scale, multinational, multicentre studies or high-quality meta-analyses will be needed to generate personalised vaccination strategies in order to achieve protective immunity in high-risk, hard-to-immunize populations.

Boosting regulatory T cell-dependent immune tolerance by activation of p53

Regulatory T cells (Tregs) have critical roles in maintaining immune hemostasis and have important anti-inflammatory functions in diseases. Recently, we identified that CX-5461 (a selective RNA polymerase I inhibitor and p53 activator) acted as a potent immunosuppressive agent, which prevented allogeneic acute rejection in animal models via a molecular mechanism distinct from all those of conventional immunosuppressive drugs. Unexpectedly, we discovered that CX-5461 could promote Treg differentiation. In this review, we have summarized the evidence for a potential role of p53 in mediating Treg differentiation and its possible mechanisms, including regulation of FoxP3 transcription, regulation of the expression of PTEN (phosphatase and tensin homolog), as well as protein-protein interaction with the transcription factor STAT5 (signal transducer and activator of transcription 5). Evidence also suggests that pharmacological p53 activators may potentially be used to boost Treg-mediated immune tolerance. Based on these data, we argue that novel p53 activators such as CX-5461 may represent a distinct class of immunosuppressants that repress conventional T cell-mediated alloimmunity with concomitant boosting of Treg-dependent immune tolerance.

Results of a multicenter cluster-randomized controlled clinical trial testing the effectiveness of a bioinformatics-enabled pharmacist intervention in transplant recipients

An ambulatory medication safety dashboard was developed to identify missing labs, concerning labs, drug interactions, nonadherence, and transitions in care. This system was tested in a 2-year, prospective, cluster-randomized, controlled multicenter study. Pharmacists at 5 intervention sites used the dashboard to address medication safety issues, compared with usual care provided at 5 control sites. A total of 2196 transplant events were included (1300 intervention vs 896 control). During the 2-year study, the intervention arm had a 11.3% (95% confidence interval, 7.1%-15.5%) absolute risk reduction of having ≥1 emergency department (ED) visit (44.2% vs 55.5%, respectively; P < .001, respectively) and a 12.3% (95% confidence interval, 8.2%-16.4%) absolute risk reduction of having ≥1 hospitalization (30.1% vs 42.4%, respectively; P < .001). In those with ≥1 event, the median ED visit rate (2 [interquartile range (IQR) 1, 5] vs 2 [IQR 1, 4]; P = .510) and hospitalization rate (2 [IQR 1, 3] vs 2 [IQR 1, 3]; P = .380) were similar. Treatment effect varied by comorbidity burden, previous ED visits or hospitalizations, and heart or lung recipients. A bioinformatics dashboard-enabled, pharmacist-led intervention reduced the risk of having at least one ED visit or hospitalization, predominantly demonstrated in lower risk patients.

Tremor Induced by Cyclosporine, Tacrolimus, Sirolimus, or Everolimus: A Review of the Literature

Calcineurin inhibitors such as cyclosporine and tacrolimus are immunosuppressant drugs that are known to induce tremors. Non-calcineurin inhibitors such as sirolimus and everolimus have also reportedly been accompanied by tremors, albeit less likely. However, the prevalence rates reported in the literature are notably wide, and the risk profiles for these drug-induced tremors are less understood. We searched PubMed to extract data on the risk of tremors with these drugs when prescribed for various transplant and non-transplant indications. We ascertained whether the risk of drug-induced tremor is influenced by the underlying diagnosis, dosing formulations, drug concentrations, and blood monitoring. We extracted data on treatment strategies and outcomes for tremors. Articles were primarily screened based on English language publications, abstracts, and studies with n ≥ 5, which included case series, retrospective studies, case-controlled studies, and prospective studies. We found 81 eligible studies comprising 33 cyclosporine, 43 tacrolimus, 6 sirolimus, and 1 everolimus that discussed tremor as an adverse event. In the pooled analysis of studies with n > 100, the incidence of tremor was 17% with cyclosporine, 21.5% with tacrolimus, and 7.8% with sirolimus and everolimus together. Regarding the underlying diagnosis, tremor was more frequently reported in kidney transplant (cyclosporine 28%, tacrolimus 30.1%) and bone marrow transplant (cyclosporine 40%, tacrolimus 41.9%) patients compared with liver transplant (cyclosporine 9%, tacrolimus 11.5%) and nontransplant indications (cyclosporine 21.5%, tacrolimus 11.3%). Most studies did not report whether the risk of tremors correlated with drug concentrations in the blood. The prevalence of tremors when using the twice-daily formulation of tacrolimus was nearly the same as the once-daily formulation (17% vs 18%). Data on individual-level risk factors for tremors were lacking. Except for three studies that found some benefit to maintaining magnesium levels, there were minimal data on treatments and outcomes. A large body of data supports a substantive and wide prevalence of tremor resulting from tacrolimus use followed by cyclosporine, especially in patients receiving a kidney transplant. However, there is little reporting on the patient-related risk factors for tremor, risk relationship with drug concentrations, treatment strategies, and outcomes.

Clinical features, treatment, and outcomes of mpox in solid organ transplant recipients: A multicenter case series and literature review

In 2022, the largest global outbreak of mpox to date emerged. In the immunocompetent host, mpox generally presents as a self-limiting illness. However, immunosuppression, such as that seen with advanced HIV, has been associated with significant morbidity and mortality related to mpox infection. To evaluate the impact of immunosuppression related to solid organ transplantation on clinical features and outcomes of mpox we established a multicenter case registry. Eleven cases from 7 participating centers in the USA were submitted. All cases occurred in males. The majority were kidney transplant recipients (91%, n = 10). Median duration of symptoms at presentation was 6 days (range, 3-14 days). Rates of hospitalization were high (73%, n = 8) with a median length of stay of 4.5 days (range, 1-10 days). Mpox in solid organ transplant recipients was associated with a high burden of skin lesions and systemic symptoms. Fever, fatigue, pharyngitis, and proctitis were commonly reported. Other clinical features included headache, myalgia, epididymo-orchitis, urinary retention, hematemesis, pneumonitis, and circulatory shock. All patients received treatment with tecovirimat. There was 1 mpox-related death in the cohort. Infection was reported to have resolved at 30-day follow-up in all other cases.

Application possibilities of artificial intelligence in facial vascularized composite allotransplantation-a narrative review

Facial vascularized composite allotransplantation (FVCA) is an emerging field of reconstructive surgery that represents a dogmatic shift in the surgical treatment of patients with severe facial disfigurements. While conventional reconstructive strategies were previously considered the goldstandard for patients with devastating facial trauma, FVCA has demonstrated promising short- and long-term outcomes. Yet, there remain several obstacles that complicate the integration of FVCA procedures into the standard workflow for facial trauma patients. Artificial intelligence (AI) has been shown to provide targeted and resource-effective solutions for persisting clinical challenges in various specialties. However, there is a paucity of studies elucidating the combination of FVCA and AI to overcome such hurdles. Here, we delineate the application possibilities of AI in the field of FVCA and discuss the use of AI technology for FVCA outcome simulation, diagnosis and prediction of rejection episodes, and malignancy screening. This line of research may serve as a fundament for future studies linking these two revolutionary biotechnologies.

Microphysiological model reveals the promise of memory-like natural killer cell immunotherapy for HIV± cancer

Numerous studies are exploring the use of cell adoptive therapies to treat hematological malignancies as well as solid tumors. However, there are numerous factors that dampen the immune response, including viruses like human immunodeficiency virus. In this study, we leverage human-derived microphysiological models to reverse-engineer the HIV-immune system interaction and evaluate the potential of memory-like natural killer cells for HIV+ head and neck cancer, one of the most common tumors in patients living with human immunodeficiency virus. Here, we evaluate multiple aspects of the memory-like natural killer cell response in human-derived bioengineered environments, including immune cell extravasation, tumor penetration, tumor killing, T cell dependence, virus suppression, and compatibility with retroviral medication. Overall, these results suggest that memory-like natural killer cells are capable of operating without T cell assistance and could simultaneously destroy head and neck cancer cells as well as reduce viral latency.

Pharmacokinetics of immunosuppressive agents during hemoperfusion in a sheep model

Introduction

Hemoadsorption shows promising signals in organ preservation and post lung transplantation. However, its potential impact on the pharmacokinetics of immunosuppressant drugs (ID) is still unknown.

Methods

In this interventional study, CytoSorb® hemoperfusion was tested in healthy sheep (n = 5) against a sham extracorporeal circuit (n = 3). Seven different ID (tacrolimus (TAC), cyclosporin A (CYA), mycophenolate mofetil (MMF), everolimus (EVER), basiliximab (BAS), methylprednisolone (MP) and prednisolone (PRED)) were administered in clinically relevant doses and combinations. Their levels were measured repeatedly in blood samples from the extracorporeal circulation over 6 h following administration. Population pharmacokinetic modeling analysis (NONMEM® 7.5) was performed.

Results

Negligible clearance was observed for PRED and BAS. For all other substances, a saturable adsorption sub-model with linear decrease of the adsorption effect over the adsorbed amount best described the measured concentrations. The maximum absolute adsorbed amounts (95% CI) for TAC, CYA, MMF, EVER, and MP were 0.040 (0.028-0.053), 1.15 (0.39-1.91), 4.17 (2.00-6.35), 0.0163 (0.007-0.026), and 53.4 mg (20.9-85.9), respectively, indicating an adsorption of less than 5% of the daily administered dosages for all investigated substances.

Discussion

In this large animal model, CytoSorb® hemoperfusion appears to have a limited effect on the clearance of tested ID.

Survival Benefit of Solid-Organ Transplantation: 10-Year Update

IMPORTANCE

Transplantation has transformed into a burgeoning field that is rapidly evolving to optimize organ distribution and survival outcomes. The years since 2012 (the last comprehensive study) have seen changes in transplantation, such as advances in immunotherapy and novel indices, that necessitate an updated analysis of survival benefit.

DESIGN

Our goal was to determine the survival benefit for solid-organ transplants in the United Network for Organ Sharing (UNOS) database for a three decade period and provide updates on advancements since 2012. Our retrospective analysis examined data containing U.S. patient records from September 1, 1987, to September 1, 2021.

RESULTS

We found that 3,430,272 life-years were saved over our transplant period (4.33 life-years saved per patient); kidney-1,998,492 life-years; liver -767,414; heart-435,312; lung-116,625; pancreas-kidney-123,463; pancreas-30,575; intestine-7901. After matching, 3,296,851 life-years were saved. Life-years saved and median survival increased for all organs between 2012 and 2021. Compared to 2012, median survival increased in kidney (from 12.4 to 14.76 years), liver (from 11.6 to 14.59), heart (9.5 to 11.73), lung (5.2 to 5.63), pancreas-kidney (from 14.5 to 16.88), pancreas (from 13.3 to 16.10). When compared to 2012, the percent transplanted increased in kidney, liver, heart, lung, and intestine, while pancreas-kidney and pancreas show decreased percent transplanted.

CONCLUSION

Our study underscores the tremendous survival benefits of solid organ transplantation (over 3.4 million life-years saved) and shows improvements since 2012. Our study also highlights areas of transplantation, notably pancreas transplants, that may necessitate reinvigorated attention.

Emerging strategies to bypass transplant rejection via biomaterial-assisted immunoengineering: Insights from islets and beyond

Novel transplantation techniques are currently under development to preserve the function of impaired tissues or organs. While current technologies can enhance the survival of recipients, they have remained elusive to date due to graft rejection by undesired in vivo immune responses despite systemic prescription of immunosuppressants. The need for life-long immunomodulation and serious adverse effects of current medicines, the development of novel biomaterial-based immunoengineering strategies has attracted much attention lately. Immunomodulatory 3D platforms can alter immune responses locally and/or prevent transplant rejection through the protection of the graft from the attack of immune system. These new approaches aim to overcome the complexity of the long-term administration of systemic immunosuppressants, including the risks of infection, cancer incidence, and systemic toxicity. In addition, they can decrease the effective dose of the delivered drugs via direct delivery at the transplantation site. In this review, we comprehensively address the immune rejection mechanisms, followed by recent developments in biomaterial-based immunoengineering strategies to prolong transplant survival. We also compare the efficacy and safety of these new platforms with conventional agents. Finally, challenges and barriers for the clinical translation of the biomaterial-based immunoengineering transplants and prospects are discussed.

Pharmaceutical care model in precision medicine in China

Pharmacy service is to provide individualized pharmaceutical care for patients, which should follow the current evidence-based pharmacy, and constantly verify the evidence and then produce new evidence. In pharmaceutical care, differences are often found in the efficacy and adverse reactions of drugs among individuals, even within individuals, which are closely related to patients' genetics, liver and kidney functions, disease states, and drug interactions. Back in the 1980s, therapeutic drug monitoring (TDM) has been applied to routinely monitor the blood drug concentration of patients taking antiepileptic drugs or immunosuppressants after transplantation to provide individualized dosage recommendations and accumulate a large amount of pharmacokinetic (PK)/pharmacodynamic (PD) data. As individualized pharmaceutical care proceeds, the concept of precision medicine was introduced into pharmacy services in combination with evidence-based pharmacy, PK/PD theories, and big data to further promote the TDM technology and drugs, and carry out pharmacogenomics analysis. The TDM and pharmacogenomics have been applied gradually to the fields of antimicrobial, antitumor, and antipsychotic drugs and immunosuppressants. Based on the concept of precision pharmacy, we adopted approaches including PK/PD, quantitative pharmacology, population pharmacokinetics, and big data machine learning to provide more personalized pharmacy services, which is mainly for special patients, such as critical patients, patients with interaction risk of multiple drugs, patients with liver and renal insufficiency, pregnant women, children, and elderly patients. As the service pattern of precision pharmacy has been constructed and constantly improved, better evidence in clinical practice will be produced to provide patients with better precision pharmacy service.

Pharmaceutical care model in precision medicine in China

Pharmacy service is to provide individualized pharmaceutical care for patients, which should follow the current evidence-based pharmacy, and constantly verify the evidence and then produce new evidence. In pharmaceutical care, differences are often found in the efficacy and adverse reactions of drugs among individuals, even within individuals, which are closely related to patient's genetics, liver and kidney functions, disease states, and drug interactions. Back in the 1980s, therapeutic drug monitoring (TDM) has been applied to routinely monitor the blood drug concentration of patients taking antiepileptic drugs or immunosuppressants after transplantation to provide individualized dosage recommendations and accumulate a large amount of pharmacokinetic (PK)/pharmacodynamic (PD) data. As individualized pharmaceutical care proceeds, the concept of precision medicine was introduced into pharmacy services in combination with evidence-based pharmacy, PK/PD theories and big data to further promote the TDM technology and drugs, and carry out pharmacogenomics analysis. The TDM and pharmacogenomics have been applied gradually to the fields of antimicrobial, antitumor and antipsychotic drugs and immunosuppressants. Based on the concept of precision pharmacy, we adpoted approaches including PK/PD, quantitative pharmacology, population pharmacokinetics, and big data machine learning to provide more personalized pharmacy services, which is mainly for special patients, such as critical patients, patients with interaction risk of multiple drugs, patients with liver and renal insufficiency, pregnant women, children and elderly patients. As the service pattern of precision pharmacy has been constructed and constantly improved, better evidence in clinical practice will be produced to provide patients with better precision pharmacy service.

Association between Hospital-Acquired Pneumonia and In-Hospital Mortality in Solid Organ Transplant Admissions: An Observational Analysis in Spain, 2004-2021

(1) Background: To analyze the association between hospital-acquired pneumonia (HAP) and in-hospital mortality (IHM) during hospital admission for solid organ transplant in Spain during 2004-2021. (2) Methods: We used national hospital discharge data to select all hospital admissions for kidney, liver, heart, and lung transplants. We stratified the data according to HAP status. To examine time trends, we grouped data into three consecutive 6-year periods (2004-2009; 2010-2015; and 2016-2021). We assessed in-hospital mortality (IHM) in logistic regression analyses and obtained odds ratios (ORs) with their 95% confidence intervals (CIs). (3) Results: We identified a total of 71,827 transplants (45,262, kidney; 18,127, liver; 4734, heart; and 4598, lung). Two thirds of the patients were men. Overall, the rate of HAP during admission was 2.6% and decreased from 3.0% during 2004-2009 to 2.4% during 2016-2021. The highest rate of HAP corresponded to lung transplant (9.4%), whereas we found the lowest rate for kidney transplant (1.1%). Rates of HAP for liver and heart transplants were 3.8% and 6.3%, respectively. IHM was significantly lower during 2016-2021 compared to 2004-2009 for all types of transplants (ORs (CIs) = 0.65 (0.53-0.79) for kidney; 0.73 (0.63-0.84) for liver; 0.72 (0.59-0.87) for heart; and 0.39 (0.31-0.47) for lung). HAP was associated with IHM for all types of transplants (ORs (CIs) = 4.47 (2.85-9.08) for kidney; 2.96 (2.34-3.75) for liver; 1.86 (1.34-2.57) for heart; and 2.97 (2.24-3.94) for lung). (4) Conclusions: Rates of HAP during admission for solid organ transplant differ depending on the type of transplant. Although IHM during admission for solid organ transplant has decreased over time in our country, HAP persists and is associated with a higher IHM after accounting for potential confounding variables.

A Comprehensive Landscape of De Novo Malignancy After Double Lung Transplantation

Although the association between post-transplant malignancy (PTM) and immunosuppressive therapy after organ transplantation has been studied, an integrated review of PTM after lung transplantation is lacking. We investigated the incidence and types of de novo PTM and its impact on survival following double lung transplantation (DLT). The incidence and type of PTM as well as the annual and cumulative risks of each malignancy after DLT were analyzed. The overall survival (OS) of recipients with or without PTM was compared by the Kaplan-Meier survival method and landmark analysis. There were 5,629 cases (23.52%) with 27 types of PTMs and incidences and OS varied according to the types of PTMs. The recipients with PTM showed a significantly longer OS than those without PTM (p < 0.001). However, while the recipients with PTM showed significantly better OS at 3, and 5 years (p < 0.001, p = 0.007), it was worse at the 10-year landmark time (p = 0.013). And the single PTM group showed a worse OS rate than the multiple PTM group (p < 0.001). This comprehensive report on PTM following DLT can help understand the risks and timing of PTM to improve the implementation of screening and treatment.

The Value of Pharmacogenomics for White and Indigenous Americans after Kidney Transplantation

BACKGROUND

There is a paucity of evidence to inform the value of pharmacogenomic (PGx) results in patients after kidney transplant and how these results differ between Indigenous Americans and Whites. This study aims to identify the frequency of recommended medication changes based on PGx results and compare the pharmacogenomic (PGx) results and patients' perceptions of the findings between a cohort of Indigenous American and White kidney transplant recipients.

METHODS

Thirty-one Indigenous Americans and fifty White kidney transplant recipients were studied prospectively. Genetic variants were identified using the OneOme RightMed PGx test of 27 genes. PGx pharmacist generated a report of the genetic variation and recommended changes. Pre- and post-qualitative patient surveys were obtained.

RESULTS

White and Indigenous American subjects had a similar mean number of medications at the time of PGx testing (mean 13 (SD 4.5)). In the entire cohort, 53% received beta blockers, 30% received antidepressants, 16% anticoagulation, 47% pain medication, and 25% statin therapy. Drug-gene interactions that warranted a clinical action were present in 21.5% of patients. In 12.7%, monitoring was recommended. Compared to the Whites, the Indigenous American patients had more normal CYP2C19 (p = 0.012) and CYP2D6 (p = 0.012) activities. The Indigenous American patients had more normal CYP4F2 (p = 0.004) and lower VKORC (p = 0.041) activities, phenotypes for warfarin drug dosing, and efficacy compared to the Whites. SLC6A4, which affects antidepressant metabolism, showed statistical differences between the two cohorts (p = 0.017); specifically, SLC6A4 had reduced expression in 45% of the Indigenous American patients compared to 20% of the White patients. There was no significant difference in patient perception before and after PGx.

CONCLUSIONS

Kidney transplant recipients had several drug-gene interactions that were clinically actionable; over one-third of patients were likely to benefit from changes in medications or drug doses based on the PGx results. The Indigenous American patients differed in the expression of drug-metabolizing enzymes and drug transporters from the White patients.

The Italian data on SARS-CoV-2 infection in transplanted patients support an organ specific immune response in liver recipients

Introduction

The study of immune response to SARSCoV-2 infection in different solid organ transplant settings represents an opportunity for clarifying the interplay between SARS-CoV-2 and the immune system. In our nationwide registry study from Italy, we specifically evaluated, during the first wave pandemic, i.e., in non-vaccinated patients, COVID-19 prevalence of infection, mortality, and lethality in liver transplant recipients (LTRs), using non-liver solid transplant recipients (NL-SOTRs) and the Italian general population (GP) as comparators.

Methods

Case collection started from February 21 to June 22, 2020, using the data from the National Institute of Health and National Transplant Center, whereas the data analysis was performed on September 30, 2020.To compare the sex- and age-adjusted distribution of infection, mortality, and lethality in LTRs, NL-SOTRs, and Italian GP we applied an indirect standardization method to determine the standardized rate.

Results

Among the 43,983 Italian SOTRs with a functioning graft, LTRs accounted for 14,168 patients, of whom 89 were SARS-CoV-2 infected. In the 29,815 NL-SOTRs, 361 cases of SARS-CoV-2 infection were observed. The geographical distribution of the disease was highly variable across the different Italian regions. The standardized rate of infection, mortality, and lethality rates in LTRs resulted lower compared to NL-SOTRs [1.02 (95%CI 0.81-1.23) vs. 2.01 (95%CI 1.8-2.2); 1.0 (95%CI 0.5-1.5) vs. 4.5 (95%CI 3.6-5.3); 1.6 (95%CI 0.7-2.4) vs. 2.8 (95%CI 2.2-3.3), respectively] and comparable to the Italian GP.

Discussion

According to the most recent studies on SOTRs and SARS-CoV-2 infection, our data strongly suggest that, in contrast to what was observed in NL-SOTRs receiving a similar immunosuppressive therapy, LTRs have the same risk of SARS-CoV-2 infection, mortality, and lethality observed in the general population. These results suggest an immune response to SARS-CoV-2 infection in LTRS that is different from NL-SOTRs, probably related to the ability of the grafted liver to induce immunotolerance.

Pathophysiology of Rejection in Kidney Transplantation

Kidney transplantation has been the optimal treatment for end-stage kidney disease for almost 70 years, with increasing frequency over this period. Despite the prevalence of the procedure, allograft rejection continues to impact transplant recipients, with consequences ranging from hospitalization to allograft failure. Rates of rejection have declined over time, which has been largely attributed to developments in immunosuppressive therapy, understanding of the immune system, and monitoring. Developments in these therapies, as well as an improved understanding of rejection risk and the epidemiology of rejection, are dependent on a foundational understanding of the pathophysiology of rejection. This review explains the interconnected mechanisms behind antibody-mediated and T-cell-mediated rejection and highlights how these processes contribute to outcomes and can inform future progress.

Infections after organ transplantation and immune response

Organ transplantation has provided another chance of survival for end-stage organ failure patients. Yet, transplant rejection is still a main challenging factor. Immunosuppressive drugs have been used to avoid rejection and suppress the immune response against allografts. Thus, immunosuppressants increase the risk of infection in immunocompromised organ transplant recipients. The infection risk reflects the relationship between the nature and severity of immunosuppression and infectious diseases. Furthermore, immunosuppressants show an immunological impact on the genetics of innate and adaptive immune responses. This effect usually reactivates the post-transplant infection in the donor and recipient tissues since T-cell activation has a substantial role in allograft rejection. Meanwhile, different infections have been found to activate the T-cells into CD₄⁺ helper T-cell subset and CD₈⁺ cytotoxic T-lymphocyte that affect the infection and the allograft. Therefore, the best management and preventive strategies of immunosuppression, antimicrobial prophylaxis, and intensive medical care are required for successful organ transplantation. This review addresses the activation of immune responses against different infections in immunocompromised individuals after organ transplantation.

Immunocompromised Host Pneumonia: Definitions and Diagnostic Criteria: An Official American Thoracic Society Workshop Report

Pneumonia imposes a significant clinical burden on people with immunocompromising conditions. Millions of individuals live with compromised immunity because of cytotoxic cancer treatments, biological therapies, organ transplants, inherited and acquired immunodeficiencies, and other immune disorders. Despite broad awareness among clinicians that these patients are at increased risk for developing infectious pneumonia, immunocompromised people are often excluded from pneumonia clinical guidelines and treatment trials. The absence of a widely accepted definition for immunocompromised host pneumonia is a significant knowledge gap that hampers consistent clinical care and research for infectious pneumonia in these vulnerable populations. To address this gap, the American Thoracic Society convened a workshop whose participants had expertise in pulmonary disease, infectious diseases, immunology, genetics, and laboratory medicine, with the goal of defining the entity of immunocompromised host pneumonia and its diagnostic criteria.

Evaluation of the interchangeability between the new fully-automated affinity chrome-mediated immunoassay (ACMIA) and the Quantitative Microsphere System (QMS) with a CE-IVD-certified LC-MS/MS assay for therapeutic drug monitoring of everolimus after solid organ transplantation

OBJECTIVES

This study aims to evaluate the interchangeability between the Siemens Healthineers' "EVRO" new affinity chrome-mediated immunoassay (ACMIA/EVRO) and Thermo Fisher Scientific's "EVER" Quantitative Microsphere System (QMS/EVER) with Chromsystems' CE-IVD-certified "MassTox" liquid-chromatography/tandem-mass spectrometry (LC-MS/MS) assay for the therapeutic drug monitoring of everolimus.

METHODS

A single lot of reagent, calibrators and controls were used for each assay. A total of 67 whole blood samples (n=67) from patients receiving solid organ transplant were analyzed (n=31 with kidney transplant and n=36 with liver transplant); Passing-Bablok regression and Bland-Altman difference plot were used to evaluate bias and individual agreement; LC-MS/MS analysis was used to measure the actual concentrations of calibrators and controls compared to the assigned value.

RESULTS

ACMIA/EVRO did not show any systematic bias compared to LC-MS/MS (intercept=0.244 ng/mL, 95% CI: -0.254 to 0.651 ng/mL). Nevertheless, significant proportional bias (slope=1.511, 95% CI: 1.420 to 1.619) associated to a combined bias of 44.8% (95% CI: 41.2-48.3%) was observed. Conversely, QMS/EVER did not show any bias at both systematic (intercept=-0.151 ng/mL, 95% CI: -0.671 to 0.256 ng/mL) and proportional level (slope=0.971, 95% CI: 0.895 to 1.074) with a non-statistically significant combined bias of -3.6% (95% CI: -8.4-1.1%). Based on a concentration of calibrators and controls above the assigned value for both the analytical methods, in the ACMIA/EVRO a correction which was approximately one-third of the correction for the QMS/EVER was observed.

CONCLUSIONS

ACMIA/EVRO but not QMS/EVER shows a lack of interchangeability with the CE-IVD-certified LC-MS/MS assay. We hypothesize that, as the ACMIA/EVRO uses an anti-sirolimus antibody, the under-corrected assigned value in the assay calibrators was not sufficient to reproduce the everolimus metabolites cross-reactivity occurring in real samples.

Antithymocyte Globulin Inhibits CD8+ T Cell Effector Functions via the Paracrine Induction of PDL-1 on Monocytes

BACKGROUND

Antithymocyte globulins (ATG) are T cell-depleting antibodies used in solid organ transplantation for induction therapy in sensitized patients with a high risk of graft rejection. Previously described effects besides the depletion of T cells have suggested additional modes of action and identified further cellular targets.

METHODS

We examined the transcriptional changes arising in immune cells from human blood after ex vivo stimulation with ATG at the single-cell level to uncover additional mechanisms by which ATG regulates T cell activity and effector functions.

FINDINGS

Analysis of the paracrine factors present in the plasma of ATG-treated whole blood revealed high levels of chemokines and cytokines, including interferon-γ (IFN-γ). Furthermore, we identified an increase in the surface expression of the programmed death ligand 1 (PDL-1) on monocytes mediated by the released paracrine factors. In addition, we showed that this induction is dependent on the activation of JAK/STAT signaling via the binding of IFN-γ to interferon-γ receptor 1 (IFN-γR1). Lastly, we demonstrated that the modulation of the immune regulatory axis of programmed cell death protein 1 (PD1) on activated CD8⁺ T cells with PDL-1 found on monocytes mediated by ATG potently inhibits effector functions including the proliferation and granzyme B release of activated T cells.

INTERPRETATION

Together, our findings represent a novel mode of action by which ATG exerts its immunosuppressive effects.

Temporal and spatial variability of immunosuppressive therapies in transplant patients: An observational study in Italy

Background

In immunosuppression after transplantation, several multi-drug approaches are used, involving calcineurin inhibitors (CNI: tacrolimus-TAC or cyclosporine-CsA), antimetabolites (antiMs), mammalian target of rapamycin inhibitors (mTORis), and corticosteroids. However, data on immunosuppressive therapy by organ and its space-time variability are lacking.

Methods

An Italian multicentre observational cohort study was conducted using health information systems. Patients with incident transplant during 2009-2019 and resident in four regions (Veneto, Lombardy, Lazio, and Sardinia) were enrolled. The post-transplant immunosuppressive regimen was evaluated by organ, region, and year.

Results

The most dispensed regimen was triple-drug therapy for the kidneys [tacrolimus (TAC) + antiM + corticosteroids = 41.5%] and heart [cyclosporin  + antiM + corticosteroids = 36.6%] and double-drug therapy for liver recipients (TAC + corticosteroids = 35.4%). Several differences between regions and years emerged with regard to agents and the number of drugs used.

Conclusion

A high heterogeneity in immunosuppressive therapy post-transplant was found. Further studies are needed in order to investigate the reasons for this variability and to evaluate the risk-benefit profile of treatment schemes adopted in clinical practice.

Human Regulatory T Cells: Understanding the Role of Tregs in Select Autoimmune Skin Diseases and Post-Transplant Nonmelanoma Skin Cancers

Regulatory T cells (Tregs) play an important role in maintaining immune tolerance and homeostasis by modulating how the immune system is activated. Several studies have documented the critical role of Tregs in suppressing the functions of effector T cells and antigen-presenting cells. Under certain conditions, Tregs can lose their suppressive capability, leading to a compromised immune system. For example, mutations in the Treg transcription factor, Forkhead box P3 (FOXP3), can drive the development of autoimmune diseases in multiple organs within the body. Furthermore, mutations leading to a reduction in the numbers of Tregs or a change in their function facilitate autoimmunity, whereas an overabundance can inhibit anti-tumor and anti-pathogen immunity. This review discusses the characteristics of Tregs and their mechanism of action in select autoimmune skin diseases, transplantation, and skin cancer. We also examine the potential of Tregs-based cellular therapies in autoimmunity.

Volumetric Absorptive Microsampling to Enhance the Therapeutic Drug Monitoring of Tacrolimus and Mycophenolic Acid: A Systematic Review and Critical Assessment

BACKGROUND

Volumetric absorptive microsampling (VAMS) is an emerging technique that may support multisample collection to enhance therapeutic drug monitoring in solid organ transplantation. This review aimed to assess whether tacrolimus and mycophenolic acid can be reliably assayed using VAMS and to identify knowledge gaps by providing granularity to existing analytical methods and clinical applications.

METHODS

A systematic literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The PubMed, Embase, and Scopus databases were accessed for records from January 2014 to April 2022 to identify scientific reports on the clinical validation of VAMS for monitoring tacrolimus and mycophenolic acid concentrations. Data on the study population, sample sources, analytical methods, and comparison results were compiled.

RESULTS

Data from 12 studies were collected, including 9 studies pertaining to tacrolimus and 3 studies on the concurrent analysis of tacrolimus and mycophenolic acid. An additional 14 studies that provided information relevant to the secondary objectives (analytical validation and clinical application) were also included. The results of the clinical validation studies generally met the method agreement requirements described by regulatory agencies, but in many cases, it was essential to apply correction factors.

CONCLUSIONSS

Current evidence suggests that the existing analytical methods that use VAMS require additional optimization steps for the analysis of tacrolimus and mycophenolic acid. The recommendations put forth in this review can help guide future studies in achieving the goal of improving the care of transplant recipients by simplifying multisample collection for the dose optimization of these drugs.

Impact of induction therapy on cytomegalovirus infection and post-transplant outcomes in pediatric heart transplant recipients receiving routine antiviral prophylaxis

OBJECTIVES

Induction therapy has been increasingly used in pediatric heart transplantation. This study evaluated the impact of anti-thymocyte globulin (ATG) versus basiliximab as induction therapy on post-transplant cytomegalovirus (CMV) infection, rejection at 1 year, coronary allograft vasculopathy (CAV), and mortality in pediatric heart transplant recipients receiving antiviral prophylaxis.

RESULTS

Of the 96 patients (age < 18 years) analyzed, 46 (47.9%) patients received basiliximab, and 50 (52.1%) received ATG. Median follow-up was 3.0 (IQR, 1.7-4.9) years with 32.3% reporting CMV infection. The ATG group, as compared with the basiliximab group, had similar incidences of CMV infection (36% vs. 28.3%, p = .418), CMV viremia (22% vs. 19.6%, p = .769), and CMV-positive tissue biopsy (30% vs. 22%, p = .486). The ATG group had lower incidences of rejection at 1 year (16% vs. 36.9%, p = .022) and CAV (4% vs. 23.9%, p = .006) with no difference in mortality (8% vs. 15.2%, p = .343), compared with the basiliximab group. Multivariate analysis showed that induction with ATG was associated with a lower risk of rejection at 1 year (OR, .31; 95% CI, .09-.94; p = .039) with no impact on the incidences of CMV infection (HR, 2.06; 95% CI, .54-7.89; p = .292), CAV (HR, .30; 95% CI, .04-2.58; p = .275), and mortality (HR, .39; 95% CI, .09-1.82; p = .233) compared to basiliximab induction.

DISCUSSION AND CONCLUSIONS

In conclusion, induction with ATG was associated with reduction in risk of rejection at 1 year with no effects on CMV infection, CAV, and mortality in pediatric heart transplant recipients with universal antiviral prophylaxis compared with basiliximab induction therapy.

Consensus on the Key Characteristics of Immunotoxic Agents as a Basis for Hazard Identification

BACKGROUND

Key characteristics (KCs), properties of agents or exposures that confer potential hazard, have been developed for carcinogens and other toxicant classes. KCs have been used in the systematic assessment of hazards and to identify assay and data gaps that limit screening and risk assessment. Many of the mechanisms through which pharmaceuticals and occupational or environmental agents modulate immune function are well recognized. Thus KCs could be identified for immunoactive substances and applied to improve hazard assessment of immunodulatory agents.

OBJECTIVES

The goal was to generate a consensus-based synthesis of scientific evidence describing the KCs of agents known to cause immunotoxicity and potential applications, such as assays to measure the KCs.

METHODS

A committee of 18 experts with diverse specialties identified 10 KCs of immunotoxic agents, namely, 1) covalently binds to proteins to form novel antigens, 2) affects antigen processing and presentation, 3) alters immune cell signaling, 4) alters immune cell proliferation, 5) modifies cellular differentiation, 6) alters immune cell-cell communication, 7) alters effector function of specific cell types, 8) alters immune cell trafficking, 9) alters cell death processes, and 10) breaks down immune tolerance. The group considered how these KCs could influence immune processes and contribute to hypersensitivity, inappropriate enhancement, immunosuppression, or autoimmunity.

DISCUSSION

KCs can be used to improve efforts to identify agents that cause immunotoxicity via one or more mechanisms, to develop better testing and biomarker approaches to evaluate immunotoxicity, and to enable a more comprehensive and mechanistic understanding of adverse effects of exposures on the immune system. https://doi.org/10.1289/EHP10800.

Immunosuppressive regimens in porcine transplantation models

Pigs, or Sus scrofa domestica, are commonly used animal models in translational transplantation research due to their anatomical, physiological, and immunological similarities to humans. In solid organ transplantation studies, immunosuppressive medications may be administered to pigs to prevent rejection. We provide an overview of the immunosuppressive regimens used in allogeneic solid organ transplantation in pigs, including heart, lung, kidney, bowel and cotransplanted organs and focus on the use of tacrolimus, mycophenolate mofetil, and corticosteroids.

A Systematic Review and Meta-Analysis of Serologic Response following Coronavirus Disease 2019 (COVID-19) Vaccination in Solid Organ Transplant Recipients

Solid organ transplant (SOT) recipients are at greater risk of coronavirus disease 2019 (COVID-19) and have attenuated response to vaccinations. In the present meta-analysis, we aimed to evaluate the serologic response to the COVID-19 vaccine in SOT recipients. A search of electronic databases was conducted to identify SOT studies that reported the serologic response to COVID-19 vaccination. We analyzed 44 observational studies including 6158 SOT recipients. Most studies were on mRNA vaccination (mRNA-1273 or BNT162b2). After a single and two doses of vaccine, serologic response rates were 8.6% (95% CI 6.8–11.0) and 34.2% (95% CI 30.1–38.7), respectively. Compared to controls, response rates were lower after a single and two doses of vaccine (OR 0.0049 [95% CI 0.0021–0.012] and 0.0057 [95% CI 0.0030–0.011], respectively). A third dose improved the rate to 65.6% (95% CI 60.4–70.2), but in a subset of patients who had not achieved a response after two doses, it remained low at 35.7% (95% CI 21.2–53.3). In summary, only a small proportion of SOT recipients achieved serologic response to the COVID-19 mRNA vaccine, and that even the third dose had an insufficient response. Alternative strategies for prophylaxis in SOT patients need to be developed. Key Contribution: In this meta-analysis that included 6158 solid organ transplant recipients, the serologic response to the COVID-19 vaccine was extremely low after one (8.6%) and two doses (34.2%). The third dose of the vaccine improved the rate only to 66%, and in the subset of patients who had not achieved a response after two doses, it remained low at 36%. The results of our study suggest that a significant proportion of solid organ transplant recipients are unable to achieve a sufficient serologic response after completing not only the two series of vaccination but also the third booster dose. There is an urgent need to develop strategies for prophylaxis including modified vaccine schedules or the use of monoclonal antibodies in this vulnerable patient population.

Artificial Intelligence: Present and Future Potential for Solid Organ Transplantation

Artificial intelligence (AI) refers to computer algorithms used to complete tasks that usually require human intelligence. Typical examples include complex decision-making and- image or speech analysis. AI application in healthcare is rapidly evolving and it undoubtedly holds an enormous potential for the field of solid organ transplantation. In this review, we provide an overview of AI-based approaches in solid organ transplantation. Particularly, we identified four key areas of transplantation which could be facilitated by AI: organ allocation and donor-recipient pairing, transplant oncology, real-time immunosuppression regimes, and precision transplant pathology. The potential implementations are vast—from improved allocation algorithms, smart donor-recipient matching and dynamic adaptation of immunosuppression to automated analysis of transplant pathology. We are convinced that we are at the beginning of a new digital era in transplantation, and that AI has the potential to improve graft and patient survival. This manuscript provides a glimpse into how AI innovations could shape an exciting future for the transplantation community.