Immunosuppressed Organ Transplant Research Articles

Safe Procedure for Efficient Hydrodynamic Gene Transfer to Isolated Porcine Liver in Transplantation.

Although calcineurin inhibitors are very effective as immunosuppressants in organ transplantation, complete graft acceptance remains as a challenge. Transfer of genes with immunosuppressant functions could contribute to improving the clinical evolution of transplantation. In this sense, hydrodynamic injection has proven very efficacious for liver gene transfer. In the present work, the hIL-10 gene was hydrofected 'ex vivo' to pig livers during the bench surgery stage, to circumvent the cardiovascular limitations of the procedure, in a model of porcine orthotopic transplantation with a 10-day follow-up. We used IL-10 because human and porcine proteins can be differentially quantified and for its immunomodulatory pleiotropic functions. Safety (biochemical parameters and histology), expression efficacy (RNA transcription and blood protein expression), and acute inflammatory response (cytokines panel) of the procedure were evaluated. The procedure proved safe as no change in biochemical parameters was observed in treated animals, and human IL-10 was efficaciously expressed, with stationary plasma protein levels over 20 pg/mL during the follow-up. Most studied cytokines showed increments (interferon-α, IFN-α; interleukin-1β, IL-1β; tumor necrosis factor α, TNFα; interleukin-6, IL-6; interleukin-8, IL-8; interleukin-4, IL-4; and transforming growth factor-β, TGF-β) in treated animals, without deleterious effects on tissue. Collectively, the results support the potential clinical interest in this gene therapy model that would require further longer-term dose-response studies to be confirmed.

Histopathological diagnoses revealed by indication-based renal allograft biopsies: a retrospective analysis

Objectives: Although there have been several advances in post-solid organ transplantation immunosuppression medications over the last two decades, the long-term survival of renal allografts did not significantly improve. Renal allograft biopsy is a helpful tool for determining the cause of graft dysfunction and adjusting patient management. Methods: Patients who received kidney transplantation and underwent allograft biopsy in Istinye University Hospital between January 2017 and January 2023 constituted the target population of this study. Demographic parameters, clinical data and biopsy indications, and histopathological assessment results of the patients were retrospectively analyzed. Results: Overall, 74 patients were included. The histopathology results included acute T-Cell mediated rejection (TCMR) (n = 15, 20%), tubular atrophy/chronic allograft nephropathy (IFTA) (n = 11, 15%), calcineurin inhibitor (CNI) toxicity (n = 2, 3%), chronic antibody-mediated rejection (ABMR) (n = 2, 3%), borderline pathology (n = 10, 13.5%), normal histology (n = 5, 6.5%), transplant glomerulopathy (TG) (n = 5, 6.5%), acute ABMR (n = 4, 5%), acute tubular necrosis (n = 7, 9%), polyomavirus nephropathy (n = 3, 4%) and non-specific changes (n = 10, 13.5%). The C4d was positive in 12% (n = 9) of the graft biopsies. In 73% (n = 54) of cases, the treatment strategy was changed based on biopsy results. Among all patients, 19 (25.6%) lost their grafts during follow-up. Conclusions: According to the histopathological analysis results, acute TCMR, IFTA, and borderline pathology were the most common causes of renal graft dysfunction. Renal allograft biopsy led to a remarkable change in treatment strategies in a significant number of cases.

Advancing Medicine with Lipid-Based Nanosystems—The Successful Case of Liposomes

Nanomedicine, a promising area of medicine, employs nanosized tools for the diagnosis, prevention, and treatment of disease. Particularly, liposomes, lipid-based nanovesicles, are currently one of the most successful nanosystems, with extensive applications in the clinic and an increasing pipeline of products in preclinical and clinical development. These versatile nanotechnological tools are biocompatible and biodegradable, and can load a variety of molecules and, ultimately, improve the therapeutic performance of drugs while minimizing undesired side effects. In this review, we provide a brief description on liposomes' composition and classification and mainly focus on their clinical use in various areas, including disease management (e.g., cancer, fungal and bacterial infections, ocular pathologies), analgesia, vaccination, diagnostics, and immunosuppression in organ transplantation. Herein are described examples of current liposomal products already in the clinic, as well as the most recent clinical trials involving liposomes as effective and safe nanomedicine tools.

Donor-derived cell-free DNA as a diagnostic tool in transplantation.

There is a need to improve personalized immunosuppression in organ transplantation to reduce premature graft loss. Biomarkers are needed to better detect rejection, asymptomatic graft injury, and under-immunosuppression. Assessment of minimal necessary exposure to guide tapering and prevent immune activation is also important. There is robust clinical evidence from a large number of published studies supporting the role of dd-cfDNA for monitoring graft integrity and detection or exclusion of rejection. Dd-cfDNA indicates graft cell death without being rejection specific. It can be determined in plasma through droplet digital PCR using preselected SNPs or next generation sequencing. Changes in recipient cfDNA (e.g., by infection) can affect the results of dd-cfDNA fractional determination. This limitation can be overcome using absolute dd-cfDNA quantification. The combination of fractional and absolute determination including total cfDNA is recommended for meaningful interpretation of the results. The value proposition for the patient includes earlier transplant injury detection and intervention, less full blown rejection risk, an alternative to invasive biopsies, and personalized immunosuppression with potential for improved long-term outcome. Transplant physicians benefit from better immunosuppressive guidance and having an alternative when biopsies are refused or contraindicated. Further advantages are improved biopsy interpretation, less trial and error changes in immunosuppression, and less time dealing with complications. The laboratory medicine specialist can provide more effective services. Hospital management and insurance companies could benefit from more cost-effective surveillance of transplant recipients. Potential cost savings would result from fewer biopsies as a result of the tests' high negative predictive value, fewer re-transplantations, and less organ failure with return to dialysis. A pathway to implementation and metrics is suggested to measure the effectiveness of dd-cfDNA testing.

Cyclosporin A as a Potential Insecticide to Control the Asian Corn Borer Ostrinia furnacalis Guenée (Lepidoptera: Pyralidae).

Simple SummaryWhile chemical insecticides are conventionally effective for pest control, they also cause severe problems, such as insect resistance and environmental pollution. Alternative insecticides with distinct mechanisms are needed. Cyclosporin A (CsA), a polypeptide produced by fungi, is widely used as an immunosuppressant in organ transplantation. This study used Ostrinia furnacalis, a major pest of maize in Asia, as a model to investigate the insecticidal activity of CsA. CsA had marked insecticide activity against O. furnacalis larvae. Furthermore, sublethal doses of CsA caused negative effects on larval, pupal and adult development. CsA treatments suppressed reproduction, significantly decreasing the mating rate, ovary size, and numbers and hatchability of eggs. CsA showed excellent combined toxicities when mixed with five common insecticides, respectively. Importantly, CsA acts by suppressing calcineurin, which represents a novel insecticidal target. Thus, CsA has potential as a new insecticide for sustainable pest management.The long-term use of chemical insecticides has caused serious problems of insect resistance and environmental pollution; new insecticides are needed to solve this problem. Cyclosporin A (CsA) is a polypeptide produced by many fungi, which is used to prevent or treat immune rejection during organ transplantation. However, little is known about the utility of CsA as an insecticide. Therefore, this study evaluated the insecticidal activity of CsA using Ostrinia furnacalis as a model. The results demonstrated that CsA was toxic to O. furnacalis with LC50 values of 113.02 μg/g and 198.70 μg/g for newly hatched neonates and newly molted third-instar larvae, respectively. Furthermore, CsA treatment had sublethal effects on the development of O. furnacalis, and significantly reduced the fecundity of adults; this suggests that CsA has great potential to suppress O. furnacalis populations. Further analysis revealed that CsA suppressed calcineurin activity in larvae. CsA had independent or synergistic toxic effects on O. furnacalis when combined with β-cypermethrin, indoxacarb, emamectin benzoate, azadirachtin, and the Bacillus thuringiensis toxin Cry1Ac, which suggests that CsA can help prevent or manage resistance. Our study provides detailed information on the potential of CsA as an insecticide for controlling lepidopterans.

Protective effect of resveratrol on the kidney in rats under immunosuppression with tacrolimus

Background/Aim: Tacrolimus is a commonly used agent for immunosuppression in organ transplantation with known nephrotoxic effects. We think that kidney-sparing therapy should be added to current treatment protocols. We aimed to observe the protective effect of resveratrol (RSV) against the adverse effects of tacrolimus (TAC) on rat kidneys. Methods: Twenty-four rats were randomly divided into the following three groups of eight rats each: Control, TAC, and RSV. The control group was not treated in any way. Tacrolimus was administered to the TAC group. In addition to tacrolimus use, resveratrol was administered to the RSV group. At the end of the experiment, one kidney was used for histopathological examination and the other, for biochemical examination. Results were analyzed statistically. Results: IL-1β, IL-6, TNF-Alpha levels in the control group were significantly lower than those in TAC and RSV groups (IL-1; P<0.001, P<0.001, IL-6; P<0.001 P=0.002, TNF-Alpha; P<0.001, P<0.001), and those in the RSV group were significantly lower than those in the TAC group (IL-1: P=0.032, IL-6: P=0.001 TNF-Alpha: P=0.026). TAS levels of the control group were significantly higher than those of the TAC group (P=0.030). TOS and OSI levels of the control group were significantly lower than those of the TAC and RSV groups (TOS: P=0.002, P=0.012, OSI: P=0.001, P=0.004). In histopathological evaluation, the TAC group showed the highest levels of fibrosis. The differences between the control and TAC groups and the TAC and RSV groups were statistically significant (P=0.003, P=0.003). Conclusion: Resveratrol has a protective effect against the adverse effects of tacrolimus on the kidney, which may be because of its anti-inflammatory and antioxidant properties.

Immunosuppression in Kidney Transplantation: State of the Art and Current Protocols.

Currently, kidney transplantation is the best treatment option for kidney failure for a majority of eligible patients. It is associated with a better quality of life and reduced mortality as compared to staying on dialysis. Many of the improvements in kidney transplant outcomes, observed in recent decades, are due to more efficient immunosuppression strategies. Therefore, developing expertise in the management of immunosuppressive drugs is key to the success of kidney transplantation. In this review, the historical aspects of organ transplant immunosuppression are briefly addressed and the basis of the allograft immune response to contextualize the main topic is provided, which is a deeper view of the immunosuppressive agents, including their known mechanisms of action, pharmacokinetics, interactions, toxicities, and clinical use. The most commonly used immunosuppressive protocols employed based on patients' and donors' characteristics are also presented here.

Dehydroxymethylepoxyquinomicin, a novel nuclear factor-\u03baB inhibitor, prevents the development of cyclosporine A nephrotoxicity in a rat model

BackgroundCyclosporine A (CsA) is an essential immunosuppressant in organ transplantation. However, its chronic nephrotoxicity is an obstacle to long allograft survival that has not been overcome. Nuclear factor-κB (NF-κB) is activated in the renal tissue in CsA nephropathy. In this study, we aimed to investigate the effect of the specific NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), in a rat model of CsA nephrotoxicity.MethodsWe administered CsA (15 mg/kg) daily for 28 days to Sprague-Dawley rats that underwent 5/6 nephrectomy under a low-salt diet. We administered DHMEQ (8 mg/kg) simultaneously with CsA to the treatment group, daily for 28 days and evaluated its effect on CsA nephrotoxicity.ResultsDHMEQ significantly inhibited NF-κB activation and nuclear translocation due to CsA treatment. Elevated serum urea nitrogen and creatinine levels due to repeated CsA administration were significantly decreased by DHMEQ treatment (serum urea nitrogen in CsA + DHMEQ vs CsA vs control, 69 ± 6.4 vs 113.5 ± 8.8 vs 43.1 ± 1.1 mg/dL, respectively, p < 0.0001; serum creatinine in CsA + DHMEQ vs CsA vs control, 0.75 ± 0.02 vs 0.91 ± 0.02 vs 0.49 ± 0.02 mg/dL, respectively, p < 0.0001), and creatinine clearance was restored in the treatment group (CsA + DHMEQ vs CsA vs control, 2.57 ± 0.09 vs 1.94 ± 0.12 vs 4.61 ± 0.18 ml/min/kg, respectively, p < 0.0001). However, DHMEQ treatment did not alter the inhibitory effect of CsA on urinary protein secretion. The development of renal fibrosis due to chronic CsA nephrotoxicity was significantly inhibited by DHMEQ treatment (CsA + DHMEQ vs CsA vs control, 13.4 ± 7.1 vs 35.6 ± 18.4 vs 9.4 ± 5.4%, respectively, p < 0.0001), and these results reflected the results of renal functional assessment. DHMEQ treatment also had an inhibitory effect on the increased expression of chemokines, monocyte chemoattractant protein-1, and chemokine (c-c motif) ligand 5 due to repeated CsA administration, which inhibited the infiltration of macrophages and neutrophils into the renal tissue.ConclusionsThese findings suggest that DHMEQ treatment in combination therapy with CsA-based immunosuppression is beneficial to prevent the development of CsA-induced nephrotoxicity.

Abstract PR08: Noninvasive epidermal sampling as a means of genomic UV dosimetry

Abstract It is now well accepted that normal-appearing, but chronically UV-exposed skin, can harbor tremendous mutational loads while maintaining homeostatic function. Even so, clones of keratinocytes harboring tumorigenic mutations can be readily observed using targeted and whole-exome sequencing. Therefore, it may be possible to objectively measure chronic, cumulative UV exposure as a means of predicting skin cancer risk and measuring molecular responses to chemoprevention by identifying UV-driven mutations or damage in epidermal keratinocytes. However, such a methodology requires the ability to noninvasively sample normal, nonlesional skin. We have previously optimized a novel surfactant mixture that, when coupled to ultrasound or mechanical abrasion, can noninvasively sample epidermis without scarring. This process can be tuned to selectively remove epidermis only. Within hours of application, a fibrinous exudate appears over the wound and this area heals completely within 2 weeks without scarring. Using a Hairless UV-driven model of squamous cell carcinoma, we have been able to sample and perform both exome and RNA sequencing with recovery rates of about 2.5-3.5 μg /cm2 of DNA and RNA. Using this model, we demonstrated a dose-dependent increase in mutational load in normal UV-exposed skin that reflects what is seen in humans. Mice were sampled and the DNA exome was sequenced (150X) following exposure to UV. Among the 28 most mutated genes across the exome, mice sampled after 1 month of UV exposure harbored variants in an average of 12 genes. After 3 months of UV exposure, followed by 2 months of no exposure, variants were observed in an average of 22 genes (80%) of the 28, suggesting continuing evolution of clones harboring mutations in exposed epidermis. Interestingly, at this relatively low coverage, none of the genes is strongly associated with skin cancer; instead, many are not expressed, reflecting the expansion of mutational burdens without strong selection on these alterations. We then extended our efforts into humans by sampling immunosuppressed solid organ transplant recipients with markedly elevated risk for skin cancer. Sun-exposed areas had an average of 4.5 times the number of variants than sun-protected areas across targeted exome sequencing of 348 cancer-related genes at a depth of ~5000X. Over 24 genes (including TP53, ATM, NOTCH, and KMT2 family members) were identified with nonsense C-T transitions, suggesting the presence of detectable (and potentially selected) mutational patterns in cancer-related genes that correlate with clinically relevant exposure. Our results collectively suggest that noninvasive sampling and genomic interrogation of normal-appearing epidermis is feasible and potentially useful as a risk prediction and chemoprevention assessment tool. This approach is easily extended to other surface epithelia, and we are currently enhancing the sensitivity of this assay based on identification of hotspots and nontranscribed genes as identified in our model. This abstract is also being presented as Poster A32. Citation Format: Kenneth Y. Tsai, Elnara Muradova, Sandy S. Ojeda, Charles H. Adelmann, Kimberly Nguyen, Samir Mitragotri, Nishit Patel. Noninvasive epidermal sampling as a means of genomic UV dosimetry [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr PR08.

Colonic mucosa-associated lymphoid tissue in a renal transplant recipient: a case report

BackgroundExtra-gastric (particularly colonic) lymphoma of mucosa-associated lymphoid tissue in the immunosuppressed solid organ transplant recipient is rare. We report a case of low-volume mucosa-associated lymphoid tissue lymphoma with colonic and bone marrow involvement in a renal transplant recipient that has been managed conservatively.Case presentationA 62-year-old Caucasian man, 14 years after kidney transplantation, was diagnosed as having extra-nodal marginal zone lymphoma of mucosa-associated lymphoid tissue with bone marrow and colonic involvement, after a colonoscopy identified mucosa-associated lymphoid tissue lymphoma in a sessile sigmoid polyp following surveillance fecal occult blood testing that returned a positive result. A gastric biopsy showed no evidence of Helicobacter pylori, but Helicobacter pylori immunoglobulin G was positive. He received Helicobacter pylori eradication treatment and is being managed expectantly. Immunosuppression was unchanged with prednisolone, mycophenolate mofetil, and cyclosporine A. Renal allograft function has remained stable.ConclusionsThis case highlights the unexpected occurrence of colonic mucosa-associated lymphoid tissue lymphoma in a kidney transplant recipient. The case emphasizes the importance of histopathological diagnosis of colonic lesions in this patient cohort because the unusual diagnosis of low-volume mucosa-associated lymphoid tissue lymphoma can be managed expectantly as it does not appear to be clinically aggressive in the immunosuppressed solid organ transplant.

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.

Inosine 5'-Monophosphate Dehydrogenase Activity for the Longitudinal Monitoring of Mycophenolic Acid Treatment in Kidney Allograft Recipients.

Mycophenolic acid (MPA) is a standard immunosuppressant in organ transplantation. A simple monitoring biomarker for MPA treatment has not been established so far. Here, we describe inosine 5'-monophosphate dehydrogenase (IMPDH) monitoring in erythrocytes and its application to kidney allograft recipients. IMPDH activity measurements were performed using a high-performance liquid chromatography assay. Based on 4203 IMPDH measurements from 1021 patients, we retrospectively explored the dynamics early after treatment start. In addition, we analyzed the influence of clinically relevant variables on IMPDH activity in a multivariate model using data from 711 stable patients. Associations between IMPDH activity and clinical events were evaluated in hospitalized patients. We found that IMPDH activity reflects MPA exposure after 8 weeks of constant dosing. In addition to dosage, body mass index, renal function, and coimmunosuppression affected IMPDH activity. Significantly lower IMPDH activities were found in patients with biopsy-proven acute rejection as compared to patients without rejection (median [interquartile range]: 696 [358-1484] versus 1265 [867-1618] pmol xanthosine-5'-monophosphate/h/mg hemoglobin, P < 0.001). The highest IMPDH activities were observed in hospitalized patients with clinically evident MPA toxicity as compared to patients with hospitalization not related to MPA treatment (1548 [1021-2270] versus 1072 [707-1439] pmol xanthosine-5'-monophosphate/h/mg hemoglobin; P < 0.001). Receiver operating characteristic curve analyses underlined the usefulness of IMPDH to predict rejection episodes (area, 0.662; confidence interval, 0.584-0.740; P < 0.001) and MPA-associated adverse events (area, 0.632; confidence interval, 0.581-0.683; P < 0.001), respectively. IMPDH measurement in erythrocytes is a novel and useful strategy for the longitudinal monitoring of MPA treatment.

Donor-Derived Cell-Free DNA Testing in Solid Organ Transplantation: A Value Proposition.

There is a need to improve personalized immunosuppression in organ transplantation to reduce premature graft loss. More efficient biomarkers are needed to better detect rejection, asymptomatic graft injury, and under-immunosuppression. Assessment of minimal necessary exposure to guide tapering and to prevent immune activation is also important. Donor-derived cell-free DNA (dd-cfDNA) has become available for comprehensive monitoring of allograft integrity. A value proposition concept was applied to assess the potential benefits of dd-cfDNA to stakeholders (patient, transplant physician, laboratory medicine specialist, hospital management, insurance companies) involved in solid organ transplantation care. There is robust clinical evidence from more than 48 published studies supporting the role of dd-cfDNA for monitoring graft integrity and detection or exclusion of rejection. The value proposition framework was used to evaluate published key evidence regarding clinical validity, economic implications, and limitations of this approach. It has been shown that dd-cfDNA testing is essential for guiding earlier transplant injury intervention with potential for improved long-term outcome. Monitoring dd-cfDNA offers a rapid and reproducible method to detect graft injuries at an early actionable stage without protocol biopsies and allows for more effective personalized immunosuppression. The appropriate use of dd-cfDNA testing can provide both clinical and economic benefits to all transplantation stakeholders.

Regulatory cell therapy in kidney transplantation (The ONE Study): a harmonised design and analysis of seven non-randomised, single-arm, phase 1/2A trials

Use of cell-based medicinal products (CBMPs) represents a state-of-the-art approach for reducing general immunosuppression in organ transplantation. We tested multiple regulatory CBMPs in kidney transplant trials to establish the safety of regulatory CBMPs when combined with reduced immunosuppressive treatment. The ONE Study consisted of seven investigator-led, single-arm trials done internationally at eight hospitals in France, Germany, Italy, the UK, and the USA (60 week follow-up). Included patients were living-donor kidney transplant recipients aged 18 years and older. The reference group trial (RGT) was a standard-of-care group given basiliximab, tapered steroids, mycophenolate mofetil, and tacrolimus. Six non-randomised phase 1/2A cell therapy group (CTG) trials were pooled and analysed, in which patients received one of six CBMPs containing regulatory T cells, dendritic cells, or macrophages; patient selection and immunosuppression mirrored the RGT, except basiliximab induction was substituted with CBMPs and mycophenolate mofetil tapering was allowed. None of the trials were randomised and none of the individuals involved were masked. The primary endpoint was biopsy-confirmed acute rejection (BCAR) within 60 weeks after transplantation; adverse event coding was centralised. The RTG and CTG trials are registered with ClinicalTrials.gov, NCT01656135, NCT02252055, NCT02085629, NCT02244801, NCT02371434, NCT02129881, and NCT02091232. The seven trials took place between Dec 11, 2012, and Nov 14, 2018. Of 782 patients assessed for eligibility, 130 (17%) patients were enrolled and 104 were treated and included in the analysis. The 66 patients who were treated in the RGT were 73% male and had a median age of 47 years. The 38 patients who were treated across six CTG trials were 71% male and had a median age of 45 years. Standard-of-care immunosuppression in the recipients in the RGT resulted in a 12% BCAR rate (expected range 3·2-18·0). The overall BCAR rate for the six parallel CTG trials was 16%. 15 (40%) patients given CBMPs were successfully weaned from mycophenolate mofetil and maintained on tacrolimus monotherapy. Combined adverse event data and BCAR episodes from all six CTG trials revealed no safety concerns when compared with the RGT. Fewer episodes of infections were registered in CTG trials versus the RGT. Regulatory cell therapy is achievable and safe in living-donor kidney transplant recipients, and is associated with fewer infectious complications, but similar rejection rates in the first year. Therefore, immune cell therapy is a potentially useful therapeutic approach in recipients of kidney transplant to minimise the burden of general immunosuppression. The 7th EU Framework Programme.

Inhibition of tRNA Gene Transcription by the Immunosuppressant Mycophenolic Acid.

Mycophenolic acid (MPA) is the active metabolite of mycophenolate mofetil, a drug that is widely used for immunosuppression in organ transplantation and autoimmune diseases, as well as anticancer chemotherapy. It inhibits IMP dehydrogenase, a rate-limiting enzyme in de novo synthesis of guanidine nucleotides. MPA treatment interferes with transcription elongation, resulting in a drastic reduction of pre-rRNA and pre-tRNA synthesis, the disruption of the nucleolus, and consequently cell cycle arrest. Here, we investigated the mechanism whereby MPA inhibits RNA polymerase III (Pol III) activity, in both yeast and mammalian cells. We show that MPA rapidly inhibits Pol III by depleting GTP. Although MPA treatment can activate p53, this is not required for Pol III transcriptional inhibition. The Pol III repressor MAF1 is also not responsible for inhibiting Pol III in response to MPA treatment. We show that upon MPA treatment, the levels of selected Pol III subunits decrease, but this is secondary to transcriptional inhibition. Chromatin immunoprecipitation (ChIP) experiments show that Pol III does not fully dissociate from tRNA genes in yeast treated with MPA, even though there is a sharp decrease in the levels of newly transcribed tRNAs. We propose that in yeast, GTP depletion may lead to Pol III stalling.

Proceedings From the Clinical and Scientific Innovations in Oral and Maxillofacial Surgery Conference 2019

Proceedings From the Clinical and Scientific Innovations in Oral and Maxillofacial Surgery Conference 2019

Efficacy and safety of everolimus treatment on liver transplant recipients: A meta-analysis.

Everolimus is an effective immunosuppressant in organ transplantation without impaired renal function. The present study aimed to evaluate the efficacy and safety of everolimus therapy in liver transplant recipients. A systematic literature search was conducted to identify the eligible studies. The quality of the included studies was assessed. The outcomes of interest were biopsy-proven acute rejection (BPAR), graft loss, death, renal function and adverse events. Eight trials involving 1570 participants were included. Compared to the standard exposure to calcineurin inhibitors (CNIs), the incidences of BPAR, graft loss and death were not increased in the everolimus combined with reduced CNIs group. The renal function was significantly improved after everolimus combined with reduced CNI therapy, and the glomerular filtration rate (GFR) was estimated to be elevated by 5.59 (95% CI: 2.17-9.01, P=.001) as compared to the standard exposure to CNIs. The risk of any adverse event was increased by everolimus combined with reduced CNI therapy (RR=1.22, 95% CI: 1.04-1.42, P=.01) as compared to the standard exposure to CNIs. The likelihood of infection was not associated with the regimen. Any publication bias was not identified. Although everolimus combined with reduced CNI therapy significantly improved the renal function in liver transplant recipients, it did not influence the incidence of BPAR, graft loss and death. This regimen might be associated with an increased risk of adverse events, which needs to be elucidated further.

232.5: Rate of opportunistic infection within 3 years after renal transplant using induction with alemtuzumab versus basiliximab.

Background: Induction immunosuppression in organ transplantation has yielded improved early graft function and decreased acute-rejection rates. However, infection risk remains a topic of investigation, particularly between different induction agents. The aim of our study was to compare clinical outcomes during the first 3-years after renal transplantation, with the focus on opportunistic infections, in patients who received either alemtuzumab or basiliximab for induction therapy. Methods: We included all renal transplant recipients from our center who received induction with alemtuzumab between 2011 and 2016. These patients were matched 1:2 (by age and date of transplant) to renal transplant recipients who received basiliximab. Electronic medical records were searched for evidence of the following opportunistic infections within the first 3 years after transplant; BK virus, CMV, VZV, HSV, Cryptococcus, and Histoplasma. Continuous variables were compared using t-tests or Wilcoxon rank-sum tests and categorical variables using Fisher’s tests or chi-square tests. Binary outcomes were compared using Cochran-Mantel-Haenszel tests. Time-to-event outcomes were plotted using the Kaplan-Meier method and compared between groups using log-rank tests. Results: Patients’ demographics and select results are presented in the Table. There were no statistically significant differences in delayed graft function (p = 0.76), graft loss (p = 0.99), or rejection (p = 0.2). Opportunistic infection rates were also not significantly different during the first 3-years post-transplantation (p = 0.87). Time-to-infection (Figure 1) (p = 0.67), time-to-death (p=0.21), and time-to-rejection (p = 0.098) were similar in both groups Conclusions: Despite a difference in immunological risk between the 2 groups, we did not detect any significant differences in outcomes at 3-years post-transplantation between higher immunological risk patients receiving alemtuzumab and lower immunological risk patients receiving basiliximab. Despite previous concerns about CMV reactivation with Alemtuzumab use, infection rates were similar between groups. Surprisingly, no fungal infections were detected at 3-years post-transplant, which may represent a delay in detection of any potential risk differences.

Role of Klotho in Chronic Calcineurin Inhibitor Nephropathy.

Calcineurin inhibitors (CNIs) are the most popular immunosuppressants in organ transplantation, but nephrotoxicity is a major concern. The common mechanism underlying chronic CNI nephropathy is oxidative stress, and the process of chronic CNI nephropathy is similar to that of aging. Current studies provide evidence that antiaging Klotho protein plays an important role in protecting against oxidative stress, and its signaling is a target for preventing oxidative stress-induced aging process. In this review, we focus on the association between Klotho and oxidative stress and the protective mechanism of action of Klotho against oxidative stress in chronic CNI nephropathy. In addition, we discuss the delivery strategy for Klotho in CNI-induced nephropathy.

The PI3Kδ selective inhibitor AS2541019 suppresses donor-specific antibody production in rat cardiac and non-human primate renal allotransplant models

Long-term graft survival after organ transplantation is difficult to achieve because of the development of chronic rejection. One cause of chronic rejection arises from antibody-mediated rejection (AMR), which is dependent on the production of donor-specific antibodies (DSA). Current immunosuppression in organ transplantation is effective in preventing acute T cell-mediated rejection, but the risk of DSA production and graft loss due to AMR remains unchanged. Phosphatidylinositol-3-kinase p110δ (PI3Kδ), a member of the family of PI3K lipid kinases, is a key mediator of B cell activation, proliferation and antibody production. AS2541019 is a novel PI3Kδ selective inhibitor that prevents antibody production by inhibiting B cell immunity. The purpose of this study was to evaluate the inhibitory effect of AS2541019 on DSA production in preclinical rodent and non-human primate allotransplant models. Concomitant administration of AS2541019 with tacrolimus and mycophenolate mofetil (MMF) inhibited de novo DSA production in an ACI-to-Lewis rat cardiac allotransplant model. To predict the efficacy of AS2541019 in clinical practice, we evaluated its effects in cynomolgus monkeys. AS2541019 inhibited B cell proliferation and major histocompatibility complex (MHC) class II expression on B cells in cynomolgus monkeys. Oral administration of AS2541019 inhibited MHC class II expression on peripheral B cells and anti-tetanus toxoid antibody production. In cynomolgus monkey renal allotransplant model, concomitant administration of AS2541019 with tacrolimus and MMF significantly inhibited de novo DSA production. Together, our findings indicate that the PI3Kδ selective inhibitor AS2541019 is a potential candidate for preventing AMR development by inhibiting DSA production.