Overview of Immunosuppressive Therapy in Solid Organ Transplantation

Induced regulatory T cells as immunotherapy in allotransplantation and autoimmunity: challenges and opportunities

Regulatory T cells play a crucial role in the homeostasis of the immune response. Regulatory T cells are mainly generated in the thymus and are characterized by the expression of Foxp3, which is considered the regulatory T-cell master transcription factor. In addition, regulatory T cells can be induced from naive CD4+ T cells to express Foxp3 under specific conditions both in vivo (peripheral regulatory T cells) and in vitro (induced regulatory T cells). Both subsets of thymic regulatory T cells and peripheral regulatory T cells are necessary for the establishment of immune tolerance to self and non-self antigens. Although it has been postulated that induced regulatory T cells may be less stable compared to regulatory T cells, mainly due to epigenetic differences, accumulating evidence in animal models shows that induced regulatory T cells are stable in vivo and can be used for the treatment of inflammatory disorders, including autoimmune diseases and allogeneic transplant rejection. In this review, we describe the biological characteristics of induced regulatory T cells, as well as the key factors involved in induced regulatory T-cell transcriptional, metabolic, and epigenetic regulation, and discuss recent advances for de novo generation of stable regulatory T cells and their use as immunotherapeutic tools in different experimental models. Moreover, we discuss the challenges and considerations for the application of induced regulatory T cells in clinical trials and describe the new approaches proposed to achieve in vivo stability, including functional or metabolic reprogramming and epigenetic editing.

Alloreactive memory CD4 T cells promote transplant rejection by engaging DCs to induce innate inflammation and CD8 T cell priming

Alloreactive memory T cells have been implicated as central drivers of transplant rejection. Perplexingly, innate cytokines, such as IL-6, IL-1β, and IL-12, are also associated with rejection of organ transplants. However, the pathways of innate immune activation in allogeneic transplantation are unclear. While the role of microbial and cell death products has been previously described, we identified alloreactive memory CD4 T cells as the primary triggers of innate inflammation. Memory CD4 T cells engaged MHC II-mismatched dendritic cells (DCs), leading to the production of innate inflammatory cytokines. This innate inflammation was independent of several pattern recognition receptors and was primarily driven by TNF superfamily ligands expressed by alloreactive memory CD4 T cells. Blocking of CD40L and TNFα resulted in dampened inflammation, and mice genetically deficient in these molecules exhibited prolonged survival of cardiac allografts. Furthermore, myeloid cell and CD8 T cell infiltration into cardiac transplants was compromised in both CD40L- and TNFα-deficient recipients. Strikingly, we found that priming of naive alloreactive CD8 T cells was dependent on licensing of DCs by memory CD4 T cells. This study unravels the key mechanisms by which alloreactive memory CD4 T cells contribute to destructive pathology and transplant rejection.

Tacrolimus related diabetic ketoacidosis and hyperglycaemic hyperosmolar nonketotic syndrome: an observational, retrospective, pharmacovigilance study

BACKGROUND

Information on the incidence and risk factors for diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar nonketotic syndrome (HHNS) caused by tacrolimus has rarely been reported. This study aims to assess the spectrum of DKA/HHNS associated with tacrolimus.

METHODS

We conducted an observational, retrospective pharmacovigilance study using the Food and Drug Administration adverse event reporting system (FAERS) database. We employed the information component (IC) and reporting odds ratio (ROR) to evaluate the association between tacrolimus and DKA/HHNS.

RESULTS

A total of 232 events were identified as tacrolimus-related DKA/HHNS, 186 cases from DKA and 54 cases from HHNS. The frequency of tacrolimus-associated DKA and HHNS was found to be significantly higher compared to all other drugs. Specifically, HHNS was significantly associated with tacrolimus based on its ROR and IC. There were no significant differences in death and non-death cases in gender, age group, year of reporting and region of reporting.

CONCLUSION

Our study showed that DKA and HHNS were associated with tacrolimus use. Healthcare professionals should be aware of the possibility of DKA/HHNS following tacrolimus administration, as they were associated with an increased risk of mortality in transplant recipients.

CXCR5 + CD8 + T Cell-mediated Suppression of Humoral Alloimmunity and AMR in Mice Is Optimized With mTOR and Impaired With Calcineurin Inhibition

BACKGROUND

Adoptive cellular therapy (ACT) with antibody-suppressor CXCR5 + CD8 + T cells (CD8 + T Ab-supp ) inhibits alloantibody production, antibody-mediated rejection (AMR), and prolongs graft survival in multiple transplant mouse models. However, it is not known how conventional immunosuppressive agents impact the efficacy of CD8 + T Ab-supp ACT.

METHODS

We investigated the efficacy of CD8 + T Ab-supp cell ACT when combined with calcineurin inhibitor (CNi) or mammalian target of rapamycin inhibitor (mTORi) in a murine model of kidney transplant.

RESULTS

ACT-mediated decrease in germinal center B cells, posttransplant alloantibody titer, and amelioration of AMR in high alloantibody-producing CCR5 knockout kidney transplant recipients were impaired when ACT was combined with CNi and enhanced when combined with mTORi. CNi (but not mTORi) reduced ACT-mediated in vivo cytotoxicity of IgG + B cells and was associated with increased quantity of germinal center B cells. Neither CNi nor mTORi treatment impacted the expression of cytotoxic effector molecules (FasL, Lamp1, perforin, granzyme B) by CD8 + T Ab-supp after ACT. Concurrent treatment with CNi (but not mTORi) reduced in vivo proliferation of CD8 + T Ab-supp after ACT. The increase in quantity of splenic CD44 + CXCR5 + CD8 + T cells that occurs after ACT was reduced by concurrent treatment with CNi but not by concurrent treatment with mTORi (dose-dependent).

CONCLUSIONS

Impaired efficacy of ACT by CNi is attributed to reduced persistence and/or expansion of CD8 + T Ab-supp cells after ACT. In contrast, concurrent immunosuppression with mTORi preserves CD8 + T Ab-supp cells quantity, in vivo proliferation, and in vivo cytotoxic effector function after ACT and enhances suppression of humoral alloimmunity and AMR.

HLA gene variations and mycotoxin toxicity: Four case reports

Mycotoxins are produced by certain molds that can cause many health effects. We present four human cases of prolonged consistent mycotoxins exposure linked to genetic variations in human leukocyte antigen (HLA) alleles. The HLA-DR/DQ isotype alleles are linked to mycotoxins susceptibility due to the lack of proper immune response; individuals with these alleles are poor eliminators of mycotoxins from their system. Four subjects with variations in their HLA-DR alleles were exposed to mycotoxins from living in mold-infested houses and experienced persistent mold-related symptoms long after moving out from the mold-infested houses and only exposed to the levels of molds found in the ambient air. From one of the subjects, two urine samples were collected ~ 18 months apart after the cessation of exposure. Urinary elimination rate was extremely slow for two of the mycotoxins (ochratoxin A [OTA] and mycophenolic acid [MPA]) detected in both samples. In 18 months, decline in OTA level was only ~ 3-fold (estimated t½ of ~ 311 days) and decline in MPA level was ~ 11-fold (estimated t½ of ~ 160 days), which was ~ 10- and ~ 213-fold slower than expected in individuals without HLA-DR alleles, respectively. We estimated that ~ 4.3 and ~ 2.2 years will be required for OTA and MPA to reach < LLQ in urine, respectively. Three other subjects with variations in HLA-DR alleles were members of a family who lived in a mold-infested house for 4 years. They kept experiencing mold-related issues >2 years after moving to a non-mold-infested house. Consistent exposure was confirmed by the presence of several mycotoxins in urine >2 years after the secession of higher than background (from outdoor ambient air) exposure. This was consistent with the extremely slow elimination of mycotoxins from their system. Variations in HLA-DR alleles can, consequently, make even short periods of exposure to chronic exposure scenarios with related adverse health effects. It is, therefore, important to determine genetic predisposition as a reason for prolonged/lingering mold-related symptoms long after the cessation of higher than background exposure. Increased human exposure to mycotoxins is expected from increased mold infestation that is anticipated due to rising CO2, temperature, and humidity from the climate change with possibly increased adverse health effects, especially in individuals with genetic susceptibility to mold toxicity.

Population pharmacokinetic models of tacrolimus in paediatric solid organ transplant recipients: A systematic review

AIMS

This study aimed to provide up-to-date information on paediatric population pharmacokinetic models of tacrolimus and to identify factors influencing tacrolimus pharmacokinetic variability.

METHODS

Systematic searches in the Web of Science, PubMed, Scopus, Science Direct, Cochrane, EMBASE databases and reference lists of articles were conducted from inception to March 2023. All population pharmacokinetic studies of tacrolimus using nonlinear mixed-effect modelling in paediatric solid organ transplant patients were included.

RESULTS

Of the 21 studies reviewed, 62% developed from liver transplant recipients and 33% from kidney transplant recipients. Most studies used a 1-compartment model to describe tacrolimus pharmacokinetics. Body weight was a significant predictor for tacrolimus volume of distribution (Vd/F). The estimated Vd/F for 1-compartment models ranged from 20 to 1890 L, whereas the peripheral volume of distribution (Vp/F) for 2-compartment models was between 290 and 1520 L. Body weight, days post-transplant, CYP3A5 genotype or haematocrit were frequently reported as significant predictors of tacrolimus clearance. The estimated apparent clearance values range between 0.12 and 2.18 L/h/kg, with inter-individual variability from 13.5 to 110.0%. Only 29% of the studies assessed the generalizability of the models with external validation.

CONCLUSION

This review highlights the potential factors, modelling approaches and validation methods that impact tacrolimus pharmacokinetics in a paediatric population. The clinician could predict tacrolimus clearance based on body weight, CYP3A5 genotype, days post-transplant or haematocrit. Further research is required to determine the relationship between pharmacogenetics and tacrolimus pharmacodynamics in paediatric patients and confirm the applicability of nonlinear kinetics in this population.

Immunologic barriers in liver transplantation: a single-cell analysis of the role of mesenchymal stem cells

Background

This study aimed to analyze the biomarkers that may reliably indicate rejection or tolerance and the mechanism that underlie the induction and maintenance of liver transplantation (LT) tolerance related to immunosuppressant or mesenchymal stem cells (MSCs).

Methods

LT models of Lewis-Lewis and F344-Lewis rats were established. Lewis-Lewis rats model served as a control (Syn). F344-Lewis rats were treated with immunosuppressant alone (Allo+IS) or in combination with MSCs (Allo+IS+MSCs). Intrahepatic cell composition particularly immune cells was compared between the groups by single-cell sequencing. Analysis of subclusters, KEGG pathway analysis, and pseudotime trajectory analysis were performed to explore the potential immunoregulatory mechanisms of immunosuppressant alone or combined with MSCs.

Results

Immunosuppressants alone or combined with MSCs increases the liver tolerance, to a certain extent. Single-cell sequencing identified intrahepatic cell composition signature, including cell subpopulations of B cells, cholangiocytes, endothelial cells, erythrocytes, hepatic stellate cells, hepatocytes, mononuclear phagocytes, neutrophils, T cells, and plasmacytoid dendritic cells. Immunosuppressant particularly its combination with MSCs altered the landscape of intrahepatic cells in transplanted livers, as well as gene expression patterns in immune cells. MSCs may be included in the differentiation of T cells, classical monocytes, and non-classical monocytes.

Conclusion

These findings provided novel insights for better understanding the heterogeneity and biological functions of intrahepatic immune cells after LT treated by IS alone or in combination with MSCs. The identified markers of immune cells may serve as the immunotherapeutic targets for MSC treatment of liver transplant rejection.

[Anesthesia for organ transplant patients]

Organ transplant patients who must undergo nontransplant surgical interventions can be challenging for the anesthesiologists in charge. On the one hand, it is important to carefully monitor the graft function in the perioperative period with respect to the occurrence of a possible rejection reaction. On the other hand, the ongoing immunosuppression may have to be adapted to the perioperative requirements in terms of the active substance and the route of administration, the resulting increased risk of infection and possible side effects (e.g., myelosuppression, nephrotoxicity and impairment of wound healing) must be included in the perioperative treatment concept. Furthermore, possible persistent comorbidities of the underlying disease and physiological peculiarities as a result of the organ transplantation must be taken into account. Support can be obtained from the expertise of the respective transplantation center.

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.

Gut microbiome modulates tacrolimus pharmacokinetics through the transcriptional regulation of ABCB1

BACKGROUND

Following solid organ transplantation, tacrolimus (TAC) is an essential drug in the immunosuppressive strategy. Its use constitutes a challenge due to its narrow therapeutic index and its high inter- and intra-pharmacokinetic (PK) variability. As the contribution of the gut microbiota to drug metabolism is now emerging, it might be explored as one of the factors explaining TAC PK variability. Herein, we explored the consequences of TAC administration on the gut microbiota composition. Reciprocally, we studied the contribution of the gut microbiota to TAC PK, using a combination of in vivo and in vitro models.

RESULTS

TAC oral administration in mice resulted in compositional alterations of the gut microbiota, namely lower evenness and disturbance in the relative abundance of specific bacterial taxa. Compared to controls, mice with a lower intestinal microbial load due to antibiotics administration exhibit a 33% reduction in TAC whole blood exposure and a lower inter-individual variability. This reduction in TAC levels was strongly correlated with higher expression of the efflux transporter ABCB1 (also known as the p-glycoprotein (P-gp) or the multidrug resistance protein 1 (MDR1)) in the small intestine. Conventionalization of germ-free mice confirmed the ability of the gut microbiota to downregulate ABCB1 expression in a site-specific fashion. The functional inhibition of ABCB1 in vivo by zosuquidar formally established the implication of this efflux transporter in the modulation of TAC PK by the gut microbiota. Furthermore, we showed that polar bacterial metabolites could recapitulate the transcriptional regulation of ABCB1 by the gut microbiota, without affecting its functionality. Finally, whole transcriptome analyses pinpointed, among others, the Constitutive Androstane Receptor (CAR) as a transcription factor likely to mediate the impact of the gut microbiota on ABCB1 transcriptional regulation.

CONCLUSIONS

We highlight for the first time how the modulation of ABCB1 expression by bacterial metabolites results in changes in TAC PK, affecting not only blood levels but also the inter-individual variability. More broadly, considering the high number of drugs with unexplained PK variability transported by ABCB1, our work is of clinical importance and paves the way for incorporating the gut microbiota in prediction algorithms for dosage of such drugs. Video Abstract.

Gut Microbiota-Mediated Pharmacokinetic Drug-Drug Interactions between Mycophenolic Acid and Trimethoprim-Sulfamethoxazole in Humans

Mycophenolic acid (MPA) and trimethoprim-sulfamethoxazole (TMP-SMX) are commonly prescribed together in certain groups of patients, including solid organ transplant recipients. However, little is known about the pharmacokinetic drug-drug interactions (DDIs) between these two medications. Therefore, the present study aimed to determine the effects of TMP-SMX on MPA pharmacokinetics in humans and to find out the relationship between MPA pharmacokinetics and gut microbiota alteration. This study enrolled 16 healthy volunteers to take a single oral dose of 1000 mg mycophenolate mofetil (MMF), a prodrug of MPA, administered without and with concurrent use of TMP-SMX (320/1600 mg/day) for five days. The pharmacokinetic parameters of MPA and its glucuronide (MPAG) were measured using high-performance liquid chromatography. The composition of gut microbiota in stool samples was profiled using a 16S rRNA metagenomic sequencing technique during pre- and post-TMP-SMX treatment. Relative abundance, bacterial co-occurrence networks, and correlations between bacterial abundance and pharmacokinetic parameters were investigated. The results showed a significant decrease in systemic MPA exposure when TMP-SMX was coadministered with MMF. Analysis of the gut microbiome revealed altered relative abundance of two enriched genera, namely the genus Bacteroides and Faecalibacterium, following TMP-SMX treatment. The relative abundance of the genera Bacteroides, [Eubacterium] coprostanoligenes group, [Eubacterium] eligens group, and Ruminococcus appeared to be significantly correlated with systemic MPA exposure. Coadministration of TMP-SMX with MMF resulted in a reduction in systemic MPA exposure. The pharmacokinetic DDIs between these two drugs were attributed to the effect of TMP-SMX, a broad-spectrum antibiotic, on gut microbiota-mediated MPA metabolism.

Advancing cell-based cancer immunotherapy through stem cell engineering

Advances in cell-based therapy, particularly CAR-T cell therapy, have transformed the treatment of hematological malignancies. Although an important step forward for the field, autologous CAR-T therapies are hindered by high costs, manufacturing challenges, and limited efficacy against solid tumors. With ongoing progress in gene editing and culture techniques, engineered stem cells and their application in cell therapy are poised to address some of these challenges. Here, we review stem cell-based immunotherapy approaches, stem cell sources, gene engineering and manufacturing strategies, therapeutic platforms, and clinical trials, as well as challenges and future directions for the field.

Implementation of Blockchain Technology Could Increase Equity and Transparency in Organ Transplantation: A Narrative Review of an Emergent Tool

In the last few years, innovative technology and health care digitalization played a major role in all medical fields and a great effort worldwide to manage this large amount of data, in terms of security and digital privacy has been made by different national health systems. Blockchain technology, a peer-to-peer distributed database without centralized authority, initially applied to Bitcoin protocol, soon gained popularity, thanks to its distributed immutable nature in several non-medical fields. Therefore, the aim of the present review (PROSPERO N° CRD42022316661) is to establish a putative future role of blockchain and distribution ledger technology (DLT) in the organ transplantation field and its role to overcome inequalities. Preoperative assessment of the deceased donor, supranational crossover programs with the international waitlist databases, and reduction of black-market donations and counterfeit drugs are some of the possible applications of DLT, thanks to its distributed, efficient, secure, trackable, and immutable nature to reduce inequalities and discrimination.

Ten decadal advances in fungal biology leading towards human well-being

Fungi are an understudied resource possessing huge potential for developing products that can greatly improve human well-being. In the current paper, we highlight some important discoveries and developments in applied mycology and interdisciplinary Life Science research. These examples concern recently introduced drugs for the treatment of infections and neurological diseases; application of -OMICS techniques and genetic tools in medical mycology and the regulation of mycotoxin production; as well as some highlights of mushroom cultivaton in Asia. Examples for new diagnostic tools in medical mycology and the exploitation of new candidates for therapeutic drugs, are also given. In addition, two entries illustrating the latest developments in the use of fungi for biodegradation and fungal biomaterial production are provided. Some other areas where there have been and/or will be significant developments are also included. It is our hope that this paper will help realise the importance of fungi as a potential industrial resource and see the next two decades bring forward many new fungal and fungus-derived products.

Durability of Antibody Response after Primary Pneumococcal Double-Dose Prime-Boost Vaccination in Adult Kidney Transplant Recipients and Candidates: 18-Month Follow-Up in a Non-Blinded, Randomised Clinical Trial

Background: Pneumococcal prime-boost vaccination is recommended for solid organ transplant recipients and candidates. The long-term durability of the antibody (AB) response is unknown. The same applies to a dose-dependent immune response. Methods: We studied the durability of the vaccine response after 18 months in kidney transplant recipients (KTRs) and patients on the kidney transplant waiting list (WLPs). Both groups received either a normal dose (ND) or a double dose (DD) of the 13-valent pneumococcal conjugate vaccine and the 23-valent pneumococcal polysaccharide vaccine. The average pneumococcal AB geometric mean concentration (GMC) was evaluated. A level ≥ 1 mg/L was considered protective against invasive pneumococcal disease (IPD). Results: Sixty WLPs and 70 KTRs were included. The proportion of participants protected declined from 52% to 33% in WLPs and from 29% to 16% in KTRs, with the previously significant dose-effect in WLPs no longer present (40% DD vs. 27% ND; p = 0.273). Average pneumococcal AB GMCs remained significantly above baseline levels (all groups p ≤ 0.001). Drug-induced immunosuppression diminished the vaccine dose-effect. Conclusions: At follow-up, the pneumococcal prime-boost vaccination still provided significantly elevated average pneumococcal AB GMCs in both populations. Though the proportion of participants protected against IPD in WLP-DD and WLP-ND were statistically comparable, a DD may still be recommended for WLPs (EudraCT: 2016-004123-23).

Immunogenicity and safety of double dosage of pneumococcal vaccines in adult kidney transplant recipients and waiting list patients: A non-blinded, randomized clinical trial

BACKGROUND

Pneumococcal prime-boost vaccination is recommended for solid organ transplant recipients, but is not thoroughly tested in this population. Furthermore, a pneumococcal vaccine dose effect has never been investigated, though observed in healthy adults. To assess whether a double dose of 13-valent pneumococcal conjugate vaccine (PCV13) and of 23-valent pneumococcal polysaccharide vaccine (PPV23) increases the immunogenicity of prime-boost vaccination in kidney transplant recipients (KTRs) and patients on the kidney transplant waiting list (WLPs), a phase 3, randomized, non-blinded trial was conducted.

METHODS

KTRs and WLPs were in parallel groups assigned either normal or double dosage of both vaccines 12 weeks apart. A 'protective response' was an average geometric mean concentration ≥ 1 mg/L based on 12 vaccine shared serotype-specific IgG antibodies. Furthermore, number of antibodies with ≥ 2-fold rises and individual serotype-specific antibody concentrations were evaluated. Follow-up was 48 weeks.

RESULTS

Seventy-four KTRs and 65 WLPs were enrolled. In WLPs, double dosage resulted in a significantly higher proportion of participants with a 'protective response' (66.7%), 5 weeks after PPV23, compared to normal dosage (35.5%), p = 0.015. KTRs exhibited no dose effect. After PPV23, all four groups had increased their number of serotypes with ≥ 2-fold rises (p ≤ 0.05 for both WLPs groups; p ≤ 0.01 for both KTRs groups). Vaccines were safe, well tolerated and still immunogenic at week 48.

CONCLUSIONS

Data suggests that double dosage of pneumococcal vaccines used according to the prime-boost strategy might be recommendable for WLPs. Furthermore, our data supports PPV23́s additive effect to PCV13 in KTRs and WLPs. (EudraCT: 2016-004123-23).

Far-Infrared Therapy Decreases Orthotopic Allograft Transplantation Vasculopathy

Orthotopic allograft transplantation (OAT) is a major strategy for solid heart and kidney failure. However, the recipient’s immunity-induced chronic rejection induces OAT vasculopathy that results in donor organ failure. With the exception of immunosuppressive agents, there are currently no specific means to inhibit the occurrence of OAT vasculopathy. On the other hand, far-infrared (FIR) therapy uses low-power electromagnetic waves given by FIR, with a wavelength of 3–25 μm, to improve human physiological functions. Previous studies have shown that FIR therapy can effectively inhibit inflammation. It has also been widely used in adjuvant therapy for various clinical diseases, especially cardiovascular diseases, in recent years. Thus, we used this study to explore the feasibility of FIR in preventing OAT vasculopathy. In this study, the model of transplantation of an aorta graft from PVG/Seac rat to ACI/NKyo rat, and in vitro model of human endothelial progenitor cells (EPCs) was used. In this report, we presented that FIR therapy decreased the serious of vasculopathy in OAT-recipient ACI/NKyo rats via inhibiting proliferation of smooth muscle cells, accumulation of collagen, and infiltration of fibroblast in the vessel wall; humoral and cell-mediated immune responses were decreased in the spleen. The production of inflammatory proteins/cytokines also decreased in the plasma. Additionally, FIR therapy presented higher mobilization and circulating EPC levels associated with vessel repair in OAT-recipient ACI/NKyo rats. In vitro studies demonstrated that the underlying mechanisms of FIR therapy inhibiting OAT vasculopathy may be associated with the inhibition of the Smad2-Slug axis endothelial mesenchymal transition (EndoMT). Thus, FIR therapy may be the strategy to prevent chronic rejection-induced vasculopathy.

Therapeutic and tectonic keratoplasty with simple cryopreserved remnants of donor corneas: an 11 year retrospective case series

This study sought to describe the use of deep-frozen donor corneal remnants preserved after keratoplasty procedures for therapeutic or tectonic keratoplasty without subsequent optical keratoplasty. This single-center retrospective consecutive case series analyzed the electronic medical records of patients who had undergone therapeutic or tectonic keratoplasty using deep-frozen donor remains preserved in Optisol-GS, for the past 11 years at Keimyung University Dongsan Medical Center. Fifty-five surgical cases in 46 patients were included. Twenty-three surgical cases in 18 patients underwent therapeutic keratoplasty for refractory infectious corneal ulcer. Complete eradication of primary infection was achieved in 14 patients (77.8%). Tectonic keratoplasty were performed 32 cases in 28 patients. Twenty-seven of 28 patients were ultimately able to maintain anatomical integrity (96.4%). Mean uncorrected visual acuity improved from 1.77 ± 0.94 preoperatively to 1.31 ± 0.95 at the last follow-up postoperatively in the tectonic graft group by logarithm of the minimal angle of resolution (P = 0.002). There were no cases of graft rejection. Keratoplasty using cryopreserved donor tissue is a suitable surgical alternative for infectious or non-infectious corneal ulcers in elderly patients or patients with poor general condition. It could be a viable alternative to overcome the shortage of corneal donors.

Enhanced Production of Mycophenolic Acid from Penicillium brevicompactum via Optimized Fermentation Strategy

Mycophenolic acid (MPA) is an occurring antibiotic produced through Penicillium brevicompactum. Its production was achieved by systematic process optimization under submerged fermentation. In shake flask, single-factor test experiments, Box-Behnken design (BBD) experiments, and fermentation strategy were determined, and the MPA yield was reached at 3002 ± 47, 3610 ± 51, and 4748 ± 59 µg/mL, respectively. For fermentation strategy, MPA production was 58.1% higher than that initial fermentation condition without optimization. Then, the optimized medium was further carried out in 5-L stirred fermenter for 180 h; MPA titer was increased from 3712 ± 65 µg/mL to 5786 ± 76 µg/mL, 55.9% higher than that of single-factor optimized medium. The results of this investigation will provide a vital step toward industrial-scale production of MPA.

The Effects of Bariatric Surgery and Gastrectomy on the Absorption of Drugs, Vitamins, and Mineral Elements

Bariatric surgery, which is an effective treatment for obesity, and gastrectomy, which is the primary treatment method for gastric cancer, alter the anatomy and physiology of the digestive system. Weight loss and changes in the gastrointestinal tract may affect the pharmacokinetic parameters of oral medications. Both bariatric and cancer patients use drugs chronically or temporarily. It is important to know how surgery affects their pharmacokinetics to ensure an effective and safe therapy. The Cochrane, PubMed, and Scopus databases were searched independently by two authors. The search strategy included controlled vocabulary and keywords. Studies show that bariatric surgery and gastrectomy most often reduce the time to maximum plasma concentration (t_max) and decrease the maximum plasma concentration (C_max) in comparison with the values of these parameters measured in healthy volunteers. Vitamin and mineral deficiencies are also observed. The effect depends on the type of surgery and the properties of the drug. It is recommended to use the drugs that have been tested on these groups of patients as it is possible to monitor them.

Highly Purified Alloantigen-Specific Tregs From Healthy and Chronic Kidney Disease Patients Can Be Long-Term Expanded, Maintaining a Suppressive Phenotype and Function in the Presence of Inflammatory Cytokines

The adoptive transfer of alloantigen-specific regulatory T cells (^alloTregs) has been proposed as a therapeutic alternative in kidney transplant recipients to the use of lifelong immunosuppressive drugs that cause serious side effects. However, the clinical application of ^alloTregs has been limited due to their low frequency in peripheral blood and the scarce development of efficient protocols to ensure their purity, expansion, and stability. Here, we describe a new experimental protocol that allows the long-term expansion of highly purified allospecific natural Tregs (nTregs) from both healthy controls and chronic kidney disease (CKD) patients, which maintain their phenotype and suppressive function under inflammatory conditions. Firstly, we co-cultured CellTrace Violet (CTV)-labeled Tregs from CKD patients or healthy individuals with allogeneic monocyte-derived dendritic cells in the presence of interleukin 2 (IL-2) and retinoic acid. Then, proliferating CD4⁺CD25^hiCTV⁻ Tregs (allospecific) were sorted by fluorescence-activated cell sorting (FACS) and polyclonally expanded with anti-CD3/CD28-coated beads in the presence of transforming growth factor beta (TGF-β), IL-2, and rapamycin. After 4 weeks, ^alloTregs were expanded up to 2,300 times the initial numbers with a purity of >95% (CD4⁺CD25^hiFOXP3⁺). The resulting allospecific Tregs showed high expressions of CTLA-4, LAG-3, and CD39, indicative of a highly suppressive phenotype. Accordingly, expanded ^alloTregs efficiently suppressed T-cell proliferation in an antigen-specific manner, even in the presence of inflammatory cytokines (IFN-γ, IL-4, IL-6, or TNF-α). Unexpectedly, the long-term expansion resulted in an increased methylation of the specific demethylated region of Foxp3. Interestingly, ^alloTregs from both normal individuals and CKD patients maintained their immunosuppressive phenotype and function after being expanded for two additional weeks under an inflammatory microenvironment. Finally, phenotypic and functional evaluation of cryopreserved ^alloTregs demonstrated the feasibility of long-term storage and supports the potential use of this cellular product for personalized Treg therapy in transplanted patients.

Hepatic Transplantation Raises Concern for Vascular Infrastructure Compromise: A Case Study of Debilitating Arteriovenous Malformation

The post-operative realm for hepatic transplant patients presents many challenges, but of them all, we take a deeper dive into an increased risk of associated cerebrovascular events. Cerebrovascular diseases, such as cerebral arteriovenous malformation (AVM), are a leading cause of death following a liver transplant. We present a unique case of a liver transplant patient who presented with no brainstem reflexes three months into the post-transplant period. Imaging studies revealed a ruptured AVM within the foramen magnum and cervicomedullary junction, as well as substantial cerebral hemorrhage. While establishing the exact cause of the AVM is not as trivial as it may appear, side effects associated with post-transplantation management regimens and possible congenital factors do shed some light on notable considerations. Given the potential damage associated with ruptured AVMs, poor patient outcomes are unfortunately not as rare as one would hope. This case highlights a rare but highly possible occurrence for cerebrovascular complications, specifically AVM rupture linked to liver transplantation and the systemic changes associated with a procedure as invasive as liver transplantation.

Combination of matrine and tacrolimus alleviates acute rejection in murine heart transplantation by inhibiting DCs maturation through ROS/ERK/NF-κB pathway

Matrine, an alkaloid derived from traditional Chinese herbs, has been confirmed to regulate immunity and exert anti-inflammatory effects. Matrine injection has been widely used in clinic therapy for anti-tumor and anti-inflammatory diseases. Heart transplantation(HT) is the only solution for the end-stage heart failure, but it is restricted by the cardiac allograft rejection. One of the important pathophysiological processes of post-transplantation rejection is inflammatory cell infiltration. Matrine has been shown to exert a positive protective effect against oxidative stress injury and inflammation, which likely benefits allograft survival. However, it remains unclear whether matrine inhibits alloimmunity or allograft rejection. In this study, we established the heart transplantation model in mouse and extracted bone marrow-derived dendritic cells (BMDCs) to explore the function and mechanism of matrine in heart transplantation. Moreover, combination treatment with matrine and tacrolimus(FK506) had a synergistic effect in preventing acute rejection of heart transplants. Here we found that matrine can prolong the survival of post-transplant and inhibit inflammatory cell infiltration in transplanted hearts of mice. At the same time, matrine increased Treg ratio and decreased CD4+/CD8 + ratio in mice. More importantly, matrine inhibited DCs maturation in mice and reduced oxidative damage and apoptosis in allograft hearts. Furthermore, matrine also downregulated NF-κB pathway and upregulated ERK1/2 signaling pathway. Overall, our study reveals a novel immunosuppressive agent that has the potential to reduce the side effects of existing immunosuppressive agents when used in combination with them.

The Impact of SARS-CoV-2 Infection, and Application of Immunosuppressive Agents in Kidney Transplant Recipients Suffering from COVID-19

In December 2019, the COVID-19 pandemic began to ravage the world quickly, causing unprecedented losses in human life and the economy. A statistical study revealed that the proportion of solid organ transplant (SOT) recipients with severe symptoms and deaths after being infected by SARS-CoV-2 is considerably higher than that of non-SOT recipients, and the prognosis is relatively poor. In addition, the clinical manifestation of SOT recipients suffering from COVID-19 is different from that of general COVID-19 patients. Acute kidney injury (AKI) is a common complication in COVID-19 patients, and it is likely more common among SOT recipients infected with SARS-CoV-2. Clinical experts consider that SOT recipients have long-term treatment with immunosuppressants, and the comorbidities are driven by a high rate of severe symptoms and mortality. Orthotopic kidney allograft transplantation is an effective treatment for patients suffering from end-stage kidney disease/kidney failure through which they can easily extend their life. Indeed, kidney transplant recipients have suffered significant damage during this pandemic. To effectively reduce the severity of symptoms and mortality of kidney transplant recipients suffering from COVID-19, precise application of various drugs, particularly immunosuppressants, is necessary. Therefore, herein, we will collate the current clinical experience of treating COVID-19 infection in kidney transplant recipients and discuss the adjustment of patients using immunosuppressive agents in the face of COVID-19.

Outcome of pretransplant melanoma after solid organ transplantation: an observational study

The number of patients with a history of melanoma who are awaiting a solid organ transplantation (SOT) is increasing. Few recommendations exist on the timing to transplantation after melanoma diagnosis. The aim of this study was to assess the melanoma recurrence-free survival after pretransplant melanoma (PTM). We conducted a multicenter ambispective observational study. Organ transplant recipients (OTR) with a history of PTM and complete AJCC staging were included. Thirty-seven patients (predominantly men with a renal allograft) were included. Five melanomas were in situ, 21 stage IA, 4 stage IB, 5 stage II, and 2 stage IIIB. The median post-transplantation follow-up time was 4 years. Sixty-two percent of patients were followed up more than 2 years. Recurrence-free survival since melanoma reached 89.9%, but varied significantly according to AJCC staging (P = 0.0129). Three patients presented a recurrence. Despite the rather limited sample size and a wide range of follow-up, our findings concerning the recurrence-free survival appear reassuring for in situ and stage IA PTM; accordingly, we suggest that a waiting time to transplantation is not mandatory in patients with in situ or stage IA PTM, especially whenever SOT is urgently needed. Caution is, however, needed for patients with higher stage.

Transplantation and immunosuppression: a review of novel transplant-related immunosuppressant drugs

Immunosuppressive drugs used in the transplantation period are generally defined as induction and maintenance therapy. The use of immunosuppressants, which are particularly useful and have fewer side effects, decreased both mortality and morbidity. Many drugs such as steroids, calcineurin inhibitors (cyclosporine-A, tacrolimus), antimetabolites (mycophenolate mofetil, azathioprine), and mTOR inhibitors (sirolimus, everolimus) are used as immunosuppressive agents. Although immunosuppressant drugs cause many side effects such as hypertension, infection, and hyperlipidemia, they are the agents that should be used to prevent organ rejection. This shows the importance of individualized drug use. The optimal immunosuppressive therapy post-transplant is not established. Therefore, discovering less toxic but more potent new agents is of great importance, and new experimental and clinical studies are needed in this regard.Our review discussed the mechanism of immunosuppressants, new agents' discovery, and current therapeutic protocols in the transplantation.

Botryllus schlosseri as a Unique Colonial Chordate Model for the Study and Modulation of Innate Immune Activity

Understanding the mechanisms that sustain immunological nonreactivity is essential for maintaining tissue in syngeneic and allogeneic settings, such as transplantation and pregnancy tolerance. While most transplantation rejections occur due to the adaptive immune response, the proinflammatory response of innate immunity is necessary for the activation of adaptive immunity. Botryllus schlosseri, a colonial tunicate, which is the nearest invertebrate group to the vertebrates, is devoid of T- and B-cell-based adaptive immunity. It has unique characteristics that make it a valuable model system for studying innate immunity mechanisms: (i) a natural allogeneic transplantation phenomenon that results in either fusion or rejection; (ii) whole animal regeneration and noninflammatory resorption on a weekly basis; (iii) allogeneic resorption which is comparable to human chronic rejection. Recent studies in B. schlosseri have led to the recognition of a molecular and cellular framework underlying the innate immunity loss of tolerance to allogeneic tissues. Additionally, B. schlosseri was developed as a model for studying hematopoietic stem cell (HSC) transplantation, and it provides further insights into the similarities between the HSC niches of human and B. schlosseri. In this review, we discuss why studying the molecular and cellular pathways that direct successful innate immune tolerance in B. schlosseri can provide novel insights into and potential modulations of these immune processes in humans.

P16-positive secondary tongue squamous cell carcinoma following allogeneic hematopoietic stem cell transplantation: A case report and literature review

As a method to improve the survival rate of patients with hematological malignancies, allogeneic hematopoietic stem cell transplantation (allo-HSCT) has increasingly been used for treatment. However, some potentially serious complications after allo-HSCT, including graft-versus-host disease, graft failure, infection, end-organ toxicity, and secondary malignancies, will determine the success of hematopoietic reconstitution. Here, we describe a case of a patient with p16-positive tongue squamous cell carcinoma (TSCC) following allo-HSCT. A 62-year-old man who had previously received allo-HSCT due to acute lymphocytic leukemia (AML) presented with erosions on the back of the tongue surrounded by multiple white patches, which were compatible with oral chronic graft-versus-host disease (cGVHD). During follow-up, a circular-like erosive lesion appeared on the right dorsal surface of the tongue. Biopsy of this lesion confirmed early invasive TSCC (T2N0M0). Partial glossectomy and tongue reconstruction were performed after cessation of immunosuppressants. Immunohistochemical (IHC) staining was positive for p16 and ki-67, suggesting a probable active human papillomavirus (HPV) infection. Six months after surgery, the patient showed no signs of metastasis or recurrence nor progression of oral GVHD.

Emerging nanomaterials for cancer immunotherapy

Immunotherapy is a unique approach to treat cancer that targets tumours besides triggering the immune cells. It attempts to harness the supremacy and specificity of immune cells for the regression of malignancy. The key strategy of immunotherapy is that it boosts the natural defence and manipulates the immune system at both cellular and molecular levels. Long-lasting anti-tumour response, reduced metastasis, and recurrence can be achieved with immunotherapy than conventional treatments. For example, targeting cytotoxic T-lymphocyte antigen-4 (CTLA4) by monoclonal antibody is reported as an effective strategy against cancer progression in vivo and chimeric antigen receptor (CAR) modified T-cells are known to express a stronger anti-tumour activity. CTLA4 and CAR are, therefore, beneficial in cancer immunotherapy; however, in clinical settings, both are expensive and cause adverse side effects. Nanomaterials have augmented advantages in cancer immunotherapy, besides their utility in effective delivery and diagnostics. In particular, materials based on lipids, polymers, and metals have been sought-after for delivery technologies. Moreover, the surface of nanomaterials can be engineered using ligands, antigens, and antibodies to target immune cells. In this sense, checkpoint inhibitors, cytokines, agonistic antibodies, surface receptors, and engineered T-cells are promising to regulate the immune system against tumours. Therefore, emerging nanomaterials that can be used for the treatment of cancer is the prime focus of this review. The correlation of mode of administration and biodistribution of various nanomaterials is reviewed here. Besides, the acute and chronic side effects and outcome of clinical trials in the context of cancer immunotherapy are discussed.

Safety and immunological proof-of-concept following treatment with tolerance-inducing cell products in patients with autoimmune diseases or receiving organ transplantation: A systematic review and meta-analysis of clinical trials

In the past years, translational approaches have led to early-stage clinical trials assessing safety and efficacy of tolerance-inducing cell-based treatments in patients. This review aims to determine if tolerance-inducing cell-based therapies, including dendritic cells, regulatory T cells and mesenchymal stem cells, are safe in adult patients who underwent organ transplantation or in those with autoimmune diseases, including multiple sclerosis, diabetes mellitus type 1, Crohn's disease and rheumatoid arthritis. Immunological and clinical outcomes were reviewed, to provide evidence for proof-of-concept and efficacy. To summarize the current knowledge, a systematic review and meta-analysis were conducted. A total of 8906 records were reviewed by 2 independent assessors and 48 records were included in the final quantitative analysis. The overall frequency of serious adverse events was low: 0.018 (95% CI: 0.006-0.051). Immunological outcomes could not be assessed quantitatively because of heterogeneity in outcome assessments and description as well as lack of individual data. Most randomized controlled studies were at a medium risk of bias due to open-label treatment without masking of assessors and/or patients to the intervention. In conclusion, tolerance-inducing cell-based therapies are safe. We advocate for harmonization of study protocols of trials investigating cell-based therapies, adverse event reporting and systematic inclusion of immunological outcome measures in clinical trials evaluating tolerance-inducingcell-basedtreatment. Registration: PROSPERO, registration number CRD42020170557.

Production of Mycophenolic Acid by a Newly Isolated Indigenous Penicillium glabrum

Soil-occupant fungi produce a variety of mycotoxins as secondary metabolites, one of which is mycophenolic acid (MPA), an antibiotic and immunosuppressive agent. MPA is mainly produced by several species of Penicillium, especially Penicillium brevicompactum. Here, we present the first report of MPA production by a local strain belonging to Penicillium glabrum species. We screened ascomycete cultures isolated from moldy food and fruits, as well as soils, collected from different parts of Iran. MPA production of one hundred and forty Penicillium isolates was analyzed using HPLC. Three MPA producer isolates were identified, among which the most producer was subjected to further characterization, based on morphological and microscopic analysis, as well as molecular approach (ITS, rDNA and beta-tubulin gene sequences). The results revealed that the best MPA producer belongs to P. glabrum IBRC-M 30518, and can produce 1079 mg/L MPA in Czapek-Dox medium.

The Role of CTLA4 and Its Polymorphisms in Solid Organ and Haematopoietic Stem Cell Transplantation

HLA matching, transplantation technique, or underlying disease greatly influences the probability of long-term transplantation success. It has been hypothesised that genetic variation affecting antigen presentation also contributes to the outcomes of both solid organ transplantation and allogeneic haematopoietic stem cell transplantation (AHSCT). Those genes, along with those responsible for innate and adaptive immunity, have become targets of investigation. In this review, we focus on the role of CTLA4 in the process of acute graft rejection and summarise the progress in our understanding of its role in predicting the outcome. We present the results of the latest studies investigating the link between CTLA4 gene variability and AHSCT, as well as organ transplantation outcomes. While some studies found a link between +49 A/G and −318 C/T and transplantation outcomes, comprehensive meta-analyses have failed to present any association. The most recent field reviews suggest that the −1772 T/C (rs733618) CC genotype is weakly associated with a lower risk of acute graft rejection, while +49 A/G might be clinically meaningful when investigated in the context of combinations with other polymorphisms. Studies verifying associations between 12 CTLA4 gene SNPs and AHSCT outcomes present inexplicit results. Some of the most commonly studied polymorphisms in this context include +49 A/G (rs231775) and CT60 A/G (rs3087243). The results signify that, in order to understand the role of CTLA4 and its gene polymorphisms in transplantology, further studies must be conducted.

PD-L1 cellular nanovesicles carrying rapamycin inhibit alloimmune responses in transplantation

Organ transplantation has been employed upon serious injuries, but a T-cell-mediated potent inflammatory immune response often leads to graft rejection. Immunosuppressive drugs such as rapamycin (RAPA) have to be taken after organ transplantation, but long-term use of these drugs causes severe adverse effects. Immune checkpoint pathways such as the programmed death-receptor 1/programmed death-ligand 1 (PD-1/PD-L1) provides an immunosuppressive environment, preventing excessive tissue destruction due to inflammatory immune responses. In this study, we bioengineered cell membrane-derived PD-L1 nanovesicles (PD-L1 NVs) to carry low doses of RAPA. These NVs inhibited T-cell activation and proliferation in vitro, by enhancing the PD-1/PD-L1 immune co-inhibitory signaling axis and inhibiting the mTOR pathway. Importantly, PD-L1 NVs encapsulated with rapamycin exerted stronger effects on inhibiting T-cell proliferation than PD-L1 NVs or rapamycin alone. This can be recapitulated in a mouse skin transplantation model, leading to the weakened alloimmune response and allograft tolerance. We also found that PD-L1/rapamycin vesicles have additional function to induce regulatory T cells in the recipient spleens. Our study highlighted the power of combining low-dose rapamycin and PD-L1 in the nanovesicles as immunosuppressants to promote allograft acceptance.

Apoptosis: A friend or foe in mesenchymal stem cell-based immunosuppression

Mesenchymal stem cells (MSC) are adult stem cells which reside in almost all postnatal tissue where, in juxtacrine and paracrine manner, regulate phenotype and function of immune cells, maintain tissue homeostasis, attenuate on-going inflammation and promote repair and regeneration of injured tissues. Due to their capacity to suppress detrimental immune response, MSC have been considered as potentially new therapeutic agents in the treatment of autoimmune and inflammatory diseases. It was recently revealed that apoptosis may increase anti-inflammatory properties of MSC by enhancing their capacity to induce generation of immunosuppressive phenotype in macrophages and dendritic cells. Upon phagocytosis, apoptotic MSC induce generation of immunosuppressive phenotype in monocytes/macrophages and promote production of anti-inflammatory cytokines and growth factors that attenuate inflammation and facilitate repair and regeneration of injured tissues. Importantly, immunomodulation mediated by apoptotic MSC was either similar or even better than immunomodulation accomplished by viable MSC. In contrast to viable MSC, which obtain either pro- or anti-inflammatory phenotype upon engraftment in different tissue microenvironments, apoptotic MSC were not subject to changes in their immunomodulatory characteristics upon diverse stimuli, indicating their potential for clinical use. In this chapter, we summarized current knowledge about beneficial effects of apoptotic MSC in the suppression of detrimental local and systemic immune response, and we emphasized their therapeutic potential in the treatment of inflammatory diseases.

Drug Interactions between Antimicrobial and Immunosuppressive Agents in Solid Organ Transplant Recipients

The number of allogeneic solid organ and bone marrow transplants is increasing all over the world. To prevent transplant rejection and treat acute rejection of transplant, immunosuppressant drugs are used. The outcomes of solid organ transplants have dramatically improved over last 30 years, due to availability of multiple immunosuppressive agents, with varied mechanisms of action. The use of intense immunosuppression makes the individual having undergone solid organ transplant at the risk of several serious infections, which may prove fatal. To prevent and treat these infections (when they occur), patients are often given antimicrobial prophylaxis and therapy. The use of antimicrobials can interfere with the metabolism of the immunosuppressants, and may put the patient at risk of developing severe adverse effects due to unwanted increase or decrease in the serum levels of immunosuppressive agents. Knowledge of these interactions is essential for successful management of solid organ transplant patients. We therefore decided to review the literature and present the interactions that commonly occur between these two life-saving groups of drugs.

How to cite this article: Bhagat V, Pandit RA, Ambapurkar S, Sengar M, Kulkarni AP. Drug Interactions between Antimicrobial and Immunosuppressive Agents in Solid Organ Transplant Recipients. Indian J Crit Care Med 2021;25(1):67–76.

Transplantation of encapsulated human Leydig-like cells: A novel option for the treatment of testosterone deficiency

Previous studies have demonstrated that the transplantation of alginate-poly-ʟ-lysine-alginate (APA)-encapsulated rat Leydig cells (LCs) provides a promising approach for treating testosterone deficiency (TD). Nevertheless, LCs have a limited capacity to proliferate, limiting the efficacy of LC transplantation therapy. Here, we established an efficient differentiation system to obtain functional Leydig-like cells (LLCs) from human stem Leydig cells (hSLCs). Then we injected APA-encapsulated LLCs into the abdominal cavities of castrated mice without an immunosuppressor. The APA-encapsulated cells survived and partially restored testosterone production for 90 days in vivo. More importantly, the transplantation of encapsulated LLCs ameliorated the symptoms of TD, such as fat accumulation, muscle atrophy and adipocyte accumulation in bone marrow. Overall, these results suggest that the transplantation of encapsulated LLCs is a promising new method for testosterone supplementation with potential clinical applications in TD.

Human Muscle Precursor Cells Form Human-Derived Myofibers in Skeletal Muscles of Nonhuman Primates: A Potential New Preclinical Setting to Test Myogenic Cells of Human Origin for Cell Therapy of Myopathies

This study aimed to verify if human myogenic cells could participate in muscle regeneration in macaques. This experimental setting would grant researchers a model that could better evaluate the effects of cell therapies in myopathies with a better translation to human patients. Human muscle precursor cells (MPCs) were cultured in vitro and transduced with ß-galactosidase. The cells were subsequently injected into 1-cm3 muscle regions of 6 macaques immunosuppressed with tacrolimus and dexamethasone. Allogeneic ß-galactosidase+ MPCs were injected in other regions as positive controls. Some cell-grafted regions were electroporated to induce extensive muscle regeneration. MPC-grafted regions were sampled 1 month later and analyzed by histology. There were ß-galactosidase+ myofibers in both the regions grafted with human and macaque MPCs. Electroporation increased the engraftment of human MPCs in the same way as in macaque allografts. The histological analysis (hematoxylin and eosin, CD8, and CD4 immunodetection) demonstrated an absence of cellular rejection in most MPC-grafted regions, as well as minimal lymphocytic infiltration in the regions transplanted with human MPCs in the individual with the lowest tacrolimus levels. Circulating de novo anti-donor antibodies were not detected. In conclusion, we report the successful engraftment of human myogenic cells in macaques, which was possible using tacrolimus-based immunosuppression.

Shoulder arthroplasty in solid organ transplant patients: a retrospective, match paired analysis

BACKGROUND

Several studies have evaluated total hip and knee arthroplasty in solid organ transplant (SOT) patients; however, there are limited studies evaluating shoulder arthroplasty in SOT patients. This study compares the complications and functional outcomes of SOT patients undergoing shoulder arthroplasty with a matched control group.

METHODS

The institution's database was retrospectively reviewed for patients with a history of SOT undergoing primary shoulder arthroplasty (with minimum 2-year follow-up) and compared with a control group matched for age, sex, preoperative diagnosis, and surgical procedure. Preoperative and postoperative range of motion and outcome scores, perioperative surgical and medical complications, hospital length of stay, and mortality were compared.

RESULTS

Fifteen patients with previous SOT underwent 19 shoulder arthroplasties. Thirty-four underwent 35 shoulder arthroplasties in the control group. At last follow-up, the SOT group had a significantly worse UCLA score. The SOT group had a significantly worse improvement in UCLA, active elevation, and passive elevation scores in pre- to postoperative scores. There was no difference in length of stay, infection, or surgical complications. Ninety-day readmissions, medically related complications, and required blood transfusion were significantly higher in the SOT group. There was increased mortality in the SOT compared with the control group (death occurred on average 1577 days after arthroplasty).

CONCLUSION

Shoulder arthroplasty in patients with previous SOT appears safe and effective for degenerative shoulder disorders. Patients should be counseled preoperatively that their range of motion and function may not improve as much as their nontransplant cohorts. SOT patients may have increased incidence of postoperative blood transfusions and medically related complications.

Cancer Risks in Solid Organ Transplant Recipients: Results from a Comprehensive Analysis of 72 Cohort Studies

Understanding the cancer risks in different transplant recipients helps early detection, evaluation, and treatment of post-transplant malignancies. Therefore, we performed a meta-analysis to determine the cancer risks at multiple sites for solid organ transplant recipients and their associations with tumor mutation burden (TMB), which reflects the immunogenicity. A comprehensive search of PubMed, Web of Science, EMBASE, Medline, and Cochrane Library was conducted. Random effects models were used to calculate the standardized incidence ratios (SIRs) versus the general population and determine the risks of different cancers. Linear regression (LR) was used to analyze the association between the SIRs and TMBs. Finally, seventy-two articles met our criteria, involving 2,105,122 solid organ transplant recipients. Compared with the general population, solid organ transplant recipients displayed a 2.68-fold cancer risk (SIR 2.68; 2.48-2.89; P <.001), renal transplant recipients displayed a 2.56-fold cancer risk (SIR 2.56; 2.31-2.84; P <.001), liver transplant recipients displayed a 2.45-fold cancer risk (SIR 2.45; 2.22-2.70; P <.001), heart and/or lung transplant recipients displayed a 3.72-fold cancer risk (SIR 3.72; 3.04-4.54; P <.001). The correlation coefficients between SIRs and TMBs were 0.68, 0.64, 0.59, 0.79 in solid organ recipients, renal recipients, liver recipients, heart and/or lung recipients, respectively. In conclusion, our study demonstrated that solid organ transplant recipients displayed a higher risk of some site-specific cancers, providing individualized guidance for clinicians to early detect, evaluate, and treat cancer among solid organ transplantation recipients. In addition, the increased cancer risk of solid organ transplant recipients is associated with TMB, suggesting that iatrogenic immunosuppression may contribute to the increased cancer risk in transplant recipients. (PROSPERO ID CRD42020160409).

Torque teno virus in liver diseases and after liver transplantation

Torque teno virus (TTV) has been proposed as a surrogate biomarker for immune monitoring in different patient cohorts. Historically, TTV has been associated with different liver diseases such as post-transfusion hepatitis, hepatitis B, and hepatitis C, but the virus's pathogenicity is controversial. TTV is a ubiquitous DNA virus, highly prevalent and mostly indolent in the general population. Thus, TTV viral load is more relevant than prevalence to understand TTV infection. In the context of liver transplantation, TTV viral load is modulated by the immune, viral, and inflammatory status. After liver transplantation, the TTV viral load positively correlates with the intensity of immunosuppression (IS), and low TTV viral burden is a predictor of acute rejection episodes, making it an attractive marker for the efficacy of IS. However, the TTV role as a single or a panel biomarker needs to be evaluated in further independent prospective trails.

The Role of Systems Vaccinology in Understanding the Immune Defects to Vaccination in Solid Organ Transplant Recipients

Solid organ transplant recipients (SOTRs) are at increased risk for many infections, whether viral, bacterial, or fungal, due to immunosuppressive therapy to prevent organ rejection. The same immune defects that render transplanted patients susceptible to infection dampen their immune response to vaccination. Therefore, it is vital to identify immune defects to vaccination in transplant recipients and methods to obviate them. These methods can include alternative vaccine composition, dosage, adjuvants, route of administration, timing, and re-vaccination strategies. Systems biology is a relatively new field of study, which utilizes high throughput means to better understand biological systems and predict outcomes. Systems biology approaches have been used to help obtain a global picture of immune responses to infections and vaccination (i.e. systems vaccinology), but little work has been done to use systems biology to improve vaccine efficacy in immunocompromised patients, particularly SOTRs, thus far. Systems vaccinology approaches may hold key insights to vaccination in this vulnerable population.

Use of T Cell Mediated Immune Functional Assays for Adjustment of Immunosuppressive or Anti-infective Agents in Solid Organ Transplant Recipients: A Systematic Review

Background: Defining the optimal dosage of the immunosuppressive or duration of anti-infective agents is a challenge in solid organ transplant (SOT) recipients. We aimed to systematically review the literature regarding the use of T cell mediated immune functional assays (IFAs) for adjustment of the immunosuppressive or anti-infective agents in SOT recipients. Methods: We systematically searched PubMed, Scopus, EMBASE, Web of Science (WOS), Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov to find human interventional studies or study protocols that used either in-house or commercially available IFAs for adjustment of the immunosuppressive or anti-infective agents in SOT recipients. Results: We included six clinical trials and six study protocols. Four out of the six clinical trials used interferon-γ release assays for cytomegalovirus (IGRA-CMV), and five out of the six registered study protocols planned to use IGRA-CMV for adjustment of anti-CMV antiviral (Valganciclovir) prophylaxis or preemptive therapy in SOT recipients. Primary or secondary anti-CMV prophylaxes were discontinued in SOT recipients who had positive IGRA-CMV results without an increase in the rate of CMV infection or reactivation. Among other IFAs, one clinical trial used interferon-γ release assays for tuberculosis (IGRA-TB), and one study used ImmuKnow for adjustment of the duration and dosage of isoniazid and tacrolimus, respectively. Conclusion: Our systematic review supports a promising role for the IGRA-CMVs for adjustment of the duration of anti-CMV antiviral prophylaxis in SOT recipients. There are limited data to support the use of IFAs other than IGRA-CMVs for adjustment of immunosuppressive or anti-infective agents. Further multicenter randomized clinical trials using IFAs other than IGRA-CMVs may help in personalized immunosuppressive or prophylactic anti-infective therapy in SOT recipients.

Cancer risk in heart or lung transplant recipients: A comprehensive analysis of 21 prospective cohorts

We performed a meta-analysis to determine cancer risks at multiple sites and their associations with tumor mutation burden (TMB), an index for immunogenicity, in heart or lung transplant recipients. A comprehensive search of PubMed, Web of Science, EMBASE, and Medline was conducted. Random effects models were used to calculate standardized incidence ratios (SIRs) versus the general population and to determine the risks of different cancers. Weighted linear regression (WLR) was used to analyze the associations between the SIRs and TMBs. (PROSPERO CRD42020159599). Data from 21 studies including 116,438 transplant recipients (51,173 heart transplant recipients and 65,265 lung transplant recipients) with a total follow-up of 601,330.7 person-years were analyzed. Compared with the general population, heart transplant recipients displayed a 3.13-fold higher cancer risk [SIR: 3.13; 95% confidence interval (CI): 2.38-4.13; p < 0.001]; lung transplant recipients displayed a 4.28-fold higher cancer risk [SIR: 4.28; 95% CI: 3.18-5.77; p < 0.001]. The correlation coefficients were 0.54 (p = 0.049) and 0.79 (p < 0.001) in heart and lung transplant recipients, respectively, indicating that 29% and 63% of the differences in the SIRs for cancer types might be explained by the TMBs. Our study demonstrated that both heart and lung transplant recipients displayed a higher risk of certain site-specific cancers. These findings can provide individualized guidance for clinicians for detection of cancer among heart or lung transplantation recipients. In addition, we provided evidence that increased risks of post-transplant cancers can be attributed to immunosuppression.

Predictors of tacrolimus pharmacokinetic variability: current evidences and future perspectives

INTRODUCTION

In kidney transplantation, tacrolimus (TAC) is at the cornerstone of current immunosuppressive strategies. Though because of its narrow therapeutic index, it is critical to ensure that TAC levels are maintained within this sharp window through reactive adjustments. This would allow maximizing efficiency while limiting drug-associated toxicity. However, TAC high intra- and inter-patient pharmacokinetic (PK) variability makes it more laborious to accurately predict the appropriate dosage required for a given patient.

AREAS COVERED

This review summarizes the state-of-the-art knowledge regarding drug interactions, demographic and pharmacogenetics factors as predictors of TAC PK. We provide a scoring index for each association to grade its relevance and we present practical recommendations, when possible for clinical practice.

EXPERT OPINION

The management of TAC concentration in transplanted kidney patients is as critical as it is challenging. Recommendations based on rigorous scientific evidences are lacking as knowledge of potential predictors remains limited outside of DDIs. Awareness of these limitations should pave the way for studies looking at demographic and pharmacogenetic factors as well as gut microbiota composition in order to promote tailored treatment plans. Therapeutic approaches considering patients' clinical singularities may help allowing to maintain appropriate concentration of TAC.

Epidemiological and molecular characterization of a novel adenovirus of squirrel monkeys after fatal infection during immunosuppression

Adenoviruses are a frequent cause of acute upper respiratory tract infections that can also cause disseminated disease in immunosuppressed patients. We identified a novel adenovirus, squirrel monkey adenovirus 1 (SqMAdV-1), as the cause of fatal infection in an immunocompromised squirrel monkey (Saimiri boliviensis) at the Keeling Center for Comparative Medicine and Research (KCCMR). Sequencing of SqMAdV-1 revealed that it is most closely related (80.4 % pairwise nucleotide identity) to the titi monkey (Plecturocebus cupreus) adenovirus (TMAdV). Although identified in the titi monkey, TMAdV is highly lethal in these monkeys, and they are not thought to be the natural host. While SqMAdV-1 is similar to other primate adenoviruses in size and genomic characteristics, a nucleotide polymorphism at the expected stop codon of the DNA polymerase gene results in a 126 amino acid extension at the carboxy terminus, a feature not previously observed among other primate adenoviruses. PCR testing and partial sequencing of 95 archived faecal samples from other squirrel monkeys (Saimiri boliviensis and Saimiri sciureus) housed at the KCCMR revealed the presence of three distinct, and apparently endemic species of adenoviruses. A grouping of ten squirrel monkey adenovirus variants has high similarity to SqMAdV-1. A single adenovirus variant (designated SqMAdV-3), detected in five monkeys, has similarity to tufted capuchin (Sapajus apella) adenoviruses. The largest group of adenovirus variants detected (designated SqMAdV-2.0-2.16) has very high similarity (93-99 %) to the TMAdV, suggesting that squirrel monkeys may be the natural host of the TMAdV.

Molecular mechanisms and therapeutic implications of tetrandrine and cepharanthine in T cell acute lymphoblastic leukemia and autoimmune diseases

Inappropriately activated T cells mediate autoimmune diseases and T cell acute lymphoblastic leukemia (T-ALL). Glucocorticoid and chemotherapeutic agents have largely extended lives of these patients. However, serious side effects and drug resistance often limit the prognosis of considerable number of the patients. The efficient treatment of autoimmune diseases or T-ALL with drug resistance remains an important unmet demand clinically. Bisbenzylisoquinoline alkaloids tetrandrine and cepharanthine have been applied for the treatment of certain types of autoimmune diseases and cancers, while studies on their action mechanisms and their further applications combined with glucocorticoids or chemotherapeutic agents remains to be expanded. This review introduced molecular mechanisms of tetrandrine and cepharanthine in T cells, including their therapeutic implications. Both tetrandrine and cepharnthine influence the growth of activated T cells via several kinds of signaling pathways, such as NF-κB, caspase cascades, cell cycle, MAPK, and PI3K/Akt/mTOR. According to recent preclinical and clinical studies, P-glycoprotein inhibitory effect of tetrandrine and cepharnthine could play a significant role on T cell-involved refractory diseases. Therefore, tetrandrine or cepharanthine combined with glucocorticoid or other anti-leukemia drugs would bring a new hope for patients with glucocorticoid-resistant autoimmune disease or refractory T-ALL accompanied with functional P-glycoprotein. In conclusion, bisbenzylisoquinoline alkaloids tetrandrine and cepharanthine can regulate several signaling pathways in abnormally activated T cells with low toxicity. Bisbenzylisoquinoline alkaloids deserve to be paid more attention as a lead compound to develop new drugs for the treatment of T cell-involved diseases in the future.

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.

Passenger Lymphocyte Syndrome; a Review of the Diagnosis, Treatment, and Proposed Detection Protocol

Passenger lymphocyte syndrome (PLS) is caused by the transfer of B-lymphocytes present in the donor graft into the recipient circulation following solid organ or hematopoietic stem cell transplantation. These cells may produce antibodies against the recipient's red blood cells, thereby triggering antibody dependent cytotoxicity and erythroid clearance, with potential resulting hemolysis and jaundice. Although uncommon, the true incidence is unknown because many cases are subclinical, with only serologic findings or with non significant levels of hemolysis detectable clinically or by laboratory monitoring. Thus, these cases may not be detected in the immediate perioperative period. No standardized consensus exists on screening for PLS in patients. Through a review of the literature from 2009 to 2019, we aim to approximate the incidence of this condition in different solid organ transplant settings, as well as to streamline recognition, detection, and management of PLS early in the disease course to prevent adverse outcomes and minimize invasive therapy. The resultant literature review yielded 22 case reports and 8 case series comprising 71 solid organ transplant patients. Hematopoietic stem cell transplant cases were excluded, as PLS cases related to solid organ transplant were the primary focus of this review. Our institution has traditionally handled PLS on a case-by-case basis, although we hope to improve this process through an introduction of an algorithm based on review of the literature and formalized communication with primary caregivers.