Mycophenolate mofetil dose reductions and discontinuations after gastrointestinal complications are associated with renal transplant graft failure

Enteric Pathogen Detection Using Multiplex PCR Assay in Kidney Transplant Recipients with Diarrhea-Retrospective Before-After Study

INTRODUCTION

Diarrhea is a frequent complication after kidney transplantation, however the etiology is often not identified. Multiplex PCR assays may increase the detection of diarrheal pathogens among kidney transplant recipients (KTRs), leading to improved management.

METHODS

This was a retrospective before-after study, conducted in a high-volume transplant center. In September 2017, multiplex PCR assay was introduced. We reviewed all hospitalized KTRs with diarrhea during 1/2015-8/2017 (pre-GI PCR, n = 111) and 9/2017-12/2021 (GI PCR, n = 159) and followed them for 3 years. We performed univariate and multivariate analysis for predictors of pathogen identification, introducing the study period as an independent variable.

RESULTS

Among 270 hospitalized KTRs with diarrhea, 64 (24%) had an identified diarrheal pathogen. The proportion of KTRs with an identified pathogen increased from 20% (13/64) in the pre-GI PCR to 80% (51/64) post GI PCR (p < 0.01). Of 51 KTRs with an identified pathogen in the post GI PCR, 44 (86%) were diagnosed using GI PCR. GI PCR was more likely used in younger KTRs with more recent transplantation and higher creatinine level at admission. The most common non-C. difficile diarrheal pathogens in the post-GI PCR cohort were enteropathogenic Escherichia coli (n = 23, 58%), norovirus (n = 11, 28%), and Campylobacter (n = 11, 28%). Implementing GI PCR significantly increased the detection and identification of GI pathogens (odds ratio [OR] = 21, CI 95% 10-44; p < 0.001).

CONCLUSIONS

Infectious etiologies of diarrhea were identified in a higher proportion of KTRs after the implementation of GI PCR. This emphasizes the importance of integrating this diagnostic tool into diarrhea workup in KTRs.

Reduced Dose Methotrexate and Mycophenolate Mofetil in Noninfectious Uveitis: A Sub-Analysis from the First-Line Antimetabolites as Steroid Sparing Therapy (FAST) Trial

PURPOSE

Some patients taking methotrexate (MTX) or mycophenolate mofetil (MMF) experience intolerable side effects at full doses. We evaluated whether dose reduction affected treatment outcomes in uveitis patients.

METHODS

Subanalysis of the First-line Antimetabolites as Steroid-sparing Treatment (FAST) uveitis trial. Patients were randomized to receive MTX (25 mg weekly) or MMF (3 g daily). A pre-specified dose reduction protocol could be employed for intolerable side effects. Primary analysis was performed at 6 months.

RESULTS

43/194 patients (22%) required dose reduction. 88/151 patients (58%) on maximum doses and 32/43 patients (74%) on reduced doses were deemed treatment successes at 6 months. The odds ratio point estimate (1.60, 95% CI 0.72-3.74) favored dose-reduction but this was not significant. Following reduction, adverse events improved at the subsequent study visit (79 events reduced to 63 events).

CONCLUSION

Dose reduction of antimetabolites was not associated with worse outcomes in this subanalysis of a uveitis trial.

Mycophenolate Dose Reduction in Tacrolimus-based Regimens and Long-term Kidney Transplant Outcomes in Australia and New Zealand

Background

Mycophenolate dose reduction (MDR) is associated with acute rejection and transplant failure in kidney transplant recipients (KTRs). The optimal dose to prevent rejection and reduce complications remains poorly defined in tacrolimus-based regimens.

Methods

We assessed adult KTRs from 2005 to 2017 initiated on mycophenolate mofetil 2 g/d, tacrolimus, and prednisolone from the Australia and New Zealand Dialysis and Transplant Registry. KTRs with rejection within the first 30 d posttransplant were excluded. The primary outcome was time to first rejection between 30 d and 2 y posttransplant. Mycophenolate dose was modeled as a time-varying covariate using Cox proportional hazards regression. Secondary outcomes included assessment of early MDR to <1.5 g/d within the first 6 mo posttransplant and subsequent patient and death-censored graft survival.

Results

In the primary analysis, 3590 KTRs were included. Compared with mycophenolate dose of ≥2 g/d, both 1.0-<1.5 and <1 g/d were associated with an increased risk of rejection during the 2 y posttransplant (hazard ratio [HR] 1.67; 95% confidence interval [CI], 1.29-2.16; P < 0.001 and HR 2.06; 95% CI, 1.36-3.13; P = 0.001, respectively) but not 1.5-<2 g/d (HR 1.20; 95% CI, 0.94-1.53; P = 0.14). Early MDR to <1.5 g/d occurred in 45.3% of KTRs and was an independent risk factor for death-censored graft failure (HR 1.32; 95% CI, 1.05-1.66; P = 0.016) but not death (HR 1.18; 95% CI, 0.97-1.44; P = 0.10), during a median follow-up of 5.0 (interquartile range, 2.6-8.5) y.

Conclusions

Early MDR was a risk factor for subsequent rejection and graft failure in KTRs receiving contemporary tacrolimus-based regimens.

Diarrhea after kidney transplantation: A study of risk factors and outcomes

Background

Diarrhea in kidney transplant recipients (KTRs) can be associated with significant morbidity.

Material and Methods

We evaluated 198 KTRs for a history of diarrhea post-kidney transplant at a tertiary care center in western India over 1 year. A protocol-based evaluation of diarrhea was done with respect to clinical features, diagnostic evaluation, associated acute allograft dysfunction, and its impact on long-term allograft function. Primary outcomes of interest were: chronic allograft injury (CAI) and the need for mycophenolate mofetil (MMF) withdrawal. We also assessed the effect of MMF withdrawal on the risk of the development of CAI.

Results

Eighty-five of 198 (42.5%) recipients experienced diarrhea and a total of 140 diarrheal episodes were evaluated. The mean age of these 85 recipients was 38 ± 12 years and 72 (84.7%) were males. 73 of 85 recipients were on MMF at the time of diarrhea and in 35 (48%) of them MMF withdrawal was needed for chronic and persistent symptoms. Diarrhea was attributed to infective etiologies in 90 of 140 (64.2%) cases. Among the microbiologically confirmed infective diarrheal episodes, giardia and cryptosporidium were the common pathogens in 11/28 (39%) and 6/28 (21.4%) episodes respectively. One hundred and twenty-eight episodes out of 140 (91.4%) episodes were complicated by acute allograft dysfunction. Forty-one of 85 recipients (48.2%) developed chronic allograft injury and 12 (14.1%) developed allograft rejection (acute and/or chronic). Probability of chronic allograft injury was higher in those with MMF withdrawal.

Conclusion

Diarrhea post-kidney transplant adversely affects graft function, especially after MMF withdrawal.

Perspectives on Mycophenolate Mofetil in the Management of Autoimmunity

Before becoming a cornerstone in the treatment of numerous immune-mediated diseases, mycophenolate mofetil (MMF) was first introduced as an immunosuppressive agent in transplant immunology and later received the attention of rheumatologists and clinicians involved in the management of autoimmune diseases. MMF is now a widespread immunosuppressive drug for the treatment of several conditions, including lupus nephritis, interstitial lung disease associated with systemic sclerosis, and anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis while being efficacious also as rescue therapy in various orphan diseases, including dermatomyositis and IgA-associated nephropathy. Similarly, case reports or series support a possible use of MMF in other rare autoimmune diseases. Beyond modulating lymphocyte activation, MMF acts on other immune and non-immune cells and these effects may explain the therapeutic profile of this medication. The effects of MMF are broadly characterized by the impact on the immune system and the antiproliferative and antifibrotic changes induced. In this latter case, mechanistic data on fibroblasts may in the future allow to reevaluate the use of MMF in selected patients with inflammatory arthritis or systemic sclerosis. Attention must be paid towards the possible occurrence of adverse events, such as gastrointestinal complaints and teratogenicity, while the risk of infections and cancer related to MMF needs to be further investigated.

Regulation of gut microbiota: a novel pretreatment for complications in patients who have undergone kidney transplantation

Kidney transplantation is an effective method to improve the condition of patients with end-stage renal disease. The gut microbiota significantly affects the immune system and can be used as an influencing factor to change the prognoses of patients who have undergone kidney transplantation. Recipients after kidney transplantation showed a lower abundance of Firmicutes and Faecalibacterium prausnitzii and a higher proportion of Bacteroidetes and Proteobacteria. After using prebiotics, synbiotics, and fecal microbiota transplantation to regulate the microbial community, the prognoses of patients who underwent kidney transplantation evidently improved. We aimed to determine the relationship between gut microbiota and various postoperative complications inpatients who have undergone kidney transplantation in recent years and to explore how gut microecology affects post-transplant complications. An in-depth understanding of the specific functions of gut microbiota and identification of the actual pathogenic flora during complications in patients undergoing kidney transplantation can help physicians develop strategies to restore the normal intestinal microbiome of transplant patients to maximize their survival and improve their quality of life.

The Gut Microbiota in Kidney Transplantation: A Target for Personalized Therapy?

Kidney transplantation improves quality of life, morbidity, and mortality of patients with kidney failure. However, integrated immunosuppressive therapy required to preserve graft function is associated with the development of post-transplant complications, including infections, altered immunosuppressive metabolism, gastrointestinal toxicity, and diarrhea. The gut microbiota has emerged as a potential therapeutic target for personalizing immunosuppressive therapy and managing post-transplant complications. This review reports current evidence on gut microbial dysbiosis in kidney transplant recipients, alterations in their gut microbiota associated with kidney transplantation outcomes, and the application of gut microbiota intervention therapies in treating post-transplant complications.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Mycophenolic Acid Induces the Intestinal Epithelial Barrier Damage through Mitochondrial ROS

Mycophenolic acid (MPA) may cause gastrointestinal adverse effects by damaging the intestinal epithelial barrier, the underlying mechanisms remain elusive. Studies have demonstrated that oxidative stress caused by reactive oxygen species (ROS) is linked to tight junction (TJ) proteins and apoptosis, both of which cause abnormalities in intestinal barrier function. Mitochondria, one of the main sources of ROS and abnormally high levels of ROS are linked to mitochondrial dysfunction. The aim of this study was to investigate whether MPA induces intestinal barrier dysfunction through regulation of the mitochondrial ROS. MPA-induced intestinal injury model in Kunming mice and Caco-2 cells. The effect of MPA on Caco-2 cell viability was measured by MTT; tissue diamine oxidase and endotoxin expression were determined by ELISA; expression of total proteins of ZO-1, occludin, Bax, Bcl-2, and mitochondrial proteins of Cytochrome C and Bax was measured by Western blot; and the localization of Cytochrome C with MitoTraker was observed by immunofluorescence staining. Caco-2 cell apoptosis, ROS levels, and mitochondrial membrane potential were detected by flow cytometry, while intramitochondrial ROS levels were observed by MitoSOX fluorescence staining. The results showed that MPA increased intracellular and mitochondrial ROS production to promote oxidative stress and the antioxidant NAC effectively restored ZO-1 and occludin expressions, reduced apoptosis in intestinal epithelial cells. Furthermore, we found that low concentrations of MPA caused mitochondrial damage, induced hyperpolarization of the mitochondrial membrane potential and the translocation of Cytochrome C and Bax proteins from the cytoplasm to the mitochondria. The mitochondrial protectant SS-31 reduces intracellular and intramitochondrial ROS, upregulates TJ, and reduces apoptosis. Our studies suggest that MPA-induced intestinal barrier dysfunction in vivo and in vitro is mediated, at least in part, by impairing mitochondrial function and promoting oxidative stress.

Immunosuppressive therapy after solid organ transplantation and the gut microbiota: Bidirectional interactions with clinical consequences

Our understanding of the involvement of the gut microbiota (GM) in human health has expanded exponentially over the last few decades, particularly in the fields of metabolism, inflammation, and immunology. Immunosuppressive treatment (IST) prescribed to solid organ transplant (SOT) recipients produces GM changes that affect these different processes. This review aims at describing the current knowledge of how IST changes the GM. Overall, SOT followed by IST results in persistent changes in the GM, with a consistent increase in proteobacteria including opportunistic pathobionts. In mice, Tacrolimus induces dysbiosis and metabolic disorders, and alters the intestinal barrier. The transfer of the GM from Tacrolimus-treated hosts confers immunosuppressive properties, suggesting a contributory role for the GM in this drug's efficacy. Steroids induce dysbiosis and intestinal barrier alterations, and also seem to depend partly on the GM for their immunosuppressive and metabolic effects. Mycophenolate Mofetil, frequently responsible for digestive side effects such as diarrhea and colitis, is associated with pro-inflammatory dysbiosis and increased endotoxemia. Alemtuzumab, m-TOR inhibitors, and belatacept have shown more marginal impact on the GM. Most of these observations are descriptive. Future studies should explore the underlying mechanism of IST-induced dysbiosis in order to better understand their efficacy and safety characteristics.

Schisandrin A alleviates mycophenolic acid-induced intestinal toxicity by regulating cell apoptosis and oxidative damage

The gastrointestinal side effects of mycophenolic acid affect its efficacy in kidney transplant patients, which may be due to its toxicity to the intestinal epithelial mechanical barrier, including intestinal epithelial cell apoptosis and destruction of tight junctions. The toxicity mechanism of mycophenolic acid is related to oxidative stress-mediated the activation of mitogen-activated protein kinases (MAPK). Schisandrin A (Sch A), one of the main active components of the Schisandra chinensis, can protects intestinal epithelial cells from deoxynivalenol-induced cytotoxicity and oxidative damage by antioxidant effects. The aim of this study was to investigate the protective effect and potential mechanism of Sch A on mycophenolic acid-induced damage in intestinal epithelial cell. The results showed that Sch A significantly reversed the mycophenolic acid-induced cell viability reduction, restored the expression of tight junction protein ZO-1, occludin and reduced cell apoptosis. In addition, Sch A inhibited mycophenolic acid-mediated MAPK activation and reactive oxygen species (ROS) increase. Collectively, our study showed that Sch A protected intestinal epithelial cells from mycophenolic acid intestinal toxicity, at least in part, by reducing oxidative stress and inhibiting MAPK signaling pathway.

Epidemiology and outcomes of medically attended and microbiologically confirmed bacterial foodborne infections in solid organ transplant recipients

Food-safety measures are recommended to solid organ transplant (SOT) recipients. However, the burden of foodborne infections in SOT recipients has not been established. We describe the epidemiology and outcomes of bacterial foodborne infections in a nationwide cohort including 4405 SOT recipients in Switzerland between 2008 and 2018. Participants were prospectively followed for a median of 4.2 years with systematic collection of data on infections, and patient and graft-related outcomes. We identified 151 episodes of microbiologically confirmed bacterial foodborne infections occurring in median 1.6 years (IQR 0.58-3.40) after transplantation (131 [88%] Campylobacter spp. and 15 [10%] non-typhoidal Salmonella). The cumulative incidence of bacterial foodborne infections was 4% (95% CI 3.4-4.8). Standardized incidence rates were 7.4 (95% CI 6.2-8.7) and 4.6 (95% CI 2.6-7.5) for Campylobacter and Salmonella infections, respectively. Invasive infection was more common with Salmonella (33.3% [5/15]) compared to Campylobacter (3.2% [4/125]; p = .001). Hospital and ICU admission rates were 47.7% (69/145) and 4.1% (6/145), respectively. A composite endpoint of acute rejection, graft loss, or death occurred within 30 days in 3.3% (5/151) of cases. In conclusion, in our cohort bacterial foodborne infections were late post-transplant infections and were associated with significant morbidity, supporting the need for implementation of food-safety recommendations.

Microbiota, renal disease and renal transplantation

Aim of this frontier review has been to highlight the role of microbiota in healthy subjects and in patients affected by renal diseases with particular reference to renal transplantation. The microbiota has a relevant role in conditioning the healthy status and the diseases. In particular gut microbiota is essential in the metabolism of food and has a relevant role for its relationship with the immune system. The indigenous microbiota in patients with chronic renal failure is completely different than that of the healthy subjects and pathobionts appear. This abnormality in microbiota composition is called dysbiosis and may cause a rapid deterioration of the renal function both for activating the immune system and producing large quantity of uremic toxins. Similarly, after renal trans-plantation the microbiota changes with the appearance of pathobionts, principally in the first period because of the assumption of immunosuppressive drugs and antibiotics. These changes may deeply interfere with the graft outcome causing acute rejection, renal infections, diarrhea, and renal interstitial fibrosis. In addition, change in the microbiota may modify the metabolism of immuno-suppressive drugs causing in some patients the need of modifying the immunosuppressant dosing. The restoration of the indigenous microbiota after transplantation is important, either to avoiding the complications that impair the normal renal graft, and because recent studies have documented the role of an indigenous microbiota in inducing tolerance towards the graft. The use of prebiotics, probiotics, smart bacteria and diet modification may restore the indigenous microbiota, but these studies are just at their beginning and more data are needed to draw definitive conclusions.

Gut microbiota profiles and fecal beta-glucuronidase activity in kidney transplant recipients with and without post-transplant diarrhea

Post-transplant diarrhea is a common complication after solid organ transplantation and is frequently attributed to the widely prescribed immunosuppressant mycophenolate mofetil (MMF). Given recent work identifying the relationship between MMF toxicity and gut bacterial β-glucuronidase activity, we evaluated the relationship between gut microbiota composition, fecal β-glucuronidase activity, and post-transplant diarrhea. We recruited 97 kidney transplant recipients and profiled the gut microbiota in 273 fecal specimens using 16S rRNA gene sequencing. We further characterized fecal β-glucuronidase activity in a subset of this cohort. Kidney transplant recipients with post-transplant diarrhea had decreased gut microbial diversity and decreased relative gut abundances of 12 genera when compared to those without post-transplant diarrhea (adjusted p value < .15, Wilcoxon rank sum test). Among the kidney transplant recipients with post-transplant diarrhea, those with higher fecal β-glucuronidase activity had a more prolonged course of diarrhea (≥7 days) compared to patients with lower fecal β-glucuronidase activity (91% vs 40%, p = .02, Fisher's exact test). Our data reveal post-transplant diarrhea as a complex phenomenon with decreased gut microbial diversity and commensal gut organisms. This study further links commensal bacterial metabolism with an important clinical outcome measure, suggesting fecal β-glucuronidase activity could be a novel biomarker for gastrointestinal-related MMF toxicity.

Inconsistencies in the association of clinical factors with the choice of early steroid withdrawal across kidney transplant centers: A national registry study

BACKGROUND

Approximately 30% of kidney transplant recipients undergo early steroid withdrawal (ESW) for maintenance immunosuppression. However, there is no consensus on which patients are suitable for ESW, and transplant centers may disagree on how various clinical factors characterize individual recipients' suitability for ESW.

METHODS

To examine center-level variation in the association of clinical factors with the choice of ESW, we studied 206 544 kidney transplant recipients from 278 centers in 2002-2017 using SRTR data. We conducted multi-level logistic regressions to characterize the association of clinical factors with the choice of ESW at each transplant center.

RESULTS

The association of clinical factors with the choice of ESW varied substantially across centers. We found particularly greater inconsistency in recipient age, PRA, re-transplantation, living/deceased donor, post-transplant length of stay, and delayed graft function. For example, across the entire population, re-transplantation was associated with lower odds of ESW (population odds ratio = 0.35 0.400.46 ). When estimated at each center, this odds ratio was significantly lower than the population odds ratio at 48 (17.3%) centers and significantly higher at 28 (10.1%) centers.

CONCLUSIONS

We have observed apparent inconsistencies across transplant centers in the practice of tailoring ESW to the recipient's risk profile. Standardized guidelines for ESW tailoring are needed.

Does the Microbiome Affect the Outcome of Renal Transplantation?

The role of the human microbiome in health and disease is becoming increasingly apparent. Emerging evidence suggests that the microbiome is affected by solid organ transplantation. Kidney transplantation is the gold standard treatment for End-Stage Renal Disease (ESRD), the advanced stage of Chronic Kidney Disease (CKD). The question of how ESRD and transplantation affect the microbiome and vice versa includes how the microbiome is affected by increased concentrations of toxins such as urea and creatinine (which are elevated in ESRD), whether restoration of renal function following transplantation alters the composition of the microbiome, and the impact of lifelong administration of immunosuppressive drugs on the microbiome. Changes in microbiome composition and activity have been reported in ESRD and in therapeutic immunosuppression, but the effect on the outcome of transplantation is not well-understood. Here, we consider the current evidence that changes in kidney function and immunosuppression following transplantation influence the oral, gut, and urinary microbiomes in kidney transplant patients. The potential for changes in these microbiomes to lead to disease, systemic inflammation, or rejection of the organ itself is discussed, along with the possibility that restoration of kidney function might re-establish orthobiosis.

Efficacy and Safety of a Quadruple Regimen Compared with Triple Regimens in Patients with Mycophenolic Acid-Related Gastrointestinal Complications After Renal Transplantation: A Short-Term Single-Center Study

Background

At present, there is no ideal conventional triple regimen that can effectively treat gastrointestinal (GI) complications in patients after kidney transplantation. We aimed to investigate the efficacy and safety of a quadruple regimen including standard-dose tacrolimus, low-dose enteric-coated mycophenolate sodium (EC-MPS), low-dose mizoribine (MZR), and corticosteroids, compared with regimens containing standard-dose tacrolimus, corticosteroids, plus either low-dose EC-MPS or standard-dose MZR in patients with mycophenolic acid (MPA)-related GI complications after renal transplantation.

Material/Methods

Between August 2016 and October 2018 in Qilu Hospital of Shandong University, 115 living donor kidney transplant recipients with MPA-related GI complications were enlisted in a single-center, prospective, randomized, control study. Thirty-six recipients were assigned to the low-dose EC-MPS plus low-dose MZR group, 37 recipients were assigned to the low-dose EC-MPS group, and 39 recipients were assigned to the standard-dose MZR group. We analyzed the Gastrointestinal Symptom Rating Scale (GSRS), estimated glomerular filtration rate (eGFR), graft rejection, serum creatinine, human leukocyte antigen (HLA) antibody, and the occurrence of adverse events among the 3 groups.

Results

Compared with baseline, gastrointestinal symptoms improved significantly in all 3 groups. The reduction in mean subscale scores from baseline to month 3 was more significant in the standard-dose MZR group compared with the other 2 groups. The low-dose EC-MPS plus low-dose MZR group had better renal function. The incidence of graft rejection and cytomegalovirus (CMV) and polyomavirus BK (BKV) infection, as well as the incidence of hyperuricemia, in the low-dose EC-MPS plus low-dose MZR group were all significantly reduced.

Conclusions

This quadruple regimen may be equivalent to regimens containing standard-dose tacrolimus, corticosteroids plus either low-dose EC-MPS or standard-dose MZR in improving GI symptoms after kidney transplant, and is also advantageous for kidney function, graft rejection, and the rates of adverse events.

Influence of Calcineurin Inhibitor and Sex on Mycophenolic Acid Pharmacokinetics and Adverse Effects Post-Renal Transplant

Tacrolimus or cyclosporine is prescribed with mycophenolic acid posttransplant and contributes to interpatient variability in mycophenolic acid pharmacokinetics and response. Cyclosporine inhibits enterohepatic circulation of the metabolite mycophenolic acid glucuronide, which is not described with tacrolimus. This study investigated mycophenolic acid pharmacokinetics and adverse effects in stable renal transplant recipients and the association with calcineurin inhibitors, sex, and race. Mycophenolic acid and mycophenolic acid glucuronide area under the concentration-time curve from 0 to 12 hours (AUC0-12h ) and apparent clearance were determined at steady state in 80 patients receiving cyclosporine with mycophenolate mofetil and 67 patients receiving tacrolimus with mycophenolate sodium. Gastrointestinal adverse effects and hematologic parameters were evaluated. Statistical models evaluated mycophenolic acid pharmacokinetics and adverse effects. Mycophenolic acid AUC0-12h was 1.70-fold greater with tacrolimus (68.9 ± 30.9 mg·h/L) relative to cyclosporine (40.8 ± 17.6 mg·h/L); P < .001. Target mycophenolic acid AUC0-12h of 30-60 mg·h/L was achieved in 56.3% on cyclosporine compared with 34.3% receiving tacrolimus (P < .001). Mycophenolic acid clearance was 48% slower with tacrolimus (10.6 ± 4.7 L/h) relative to cyclosporine (20.5 ± 10.0 L/h); P < .001. Enterohepatic circulation occurred less frequently with cyclosporine (45%) compared with tacrolimus (78%); P < 0.001; with a 2.9-fold greater mycophenolic acid glucuronide AUC0-12h to mycophenolic acid AUC0-12h ratio (P < .001). Race did not affect mycophenolic acid pharmacokinetics. Gastrointestinal adverse effect scores were 2.2-fold higher with tacrolimus (P < .001) and more prominent in women (P = .017). Lymphopenia was more prevalent with tacrolimus (52.2%) than cyclosporine (22.5%); P < 0.001. Calcineurin inhibitors and sex contributed to interpatient variability in mycophenolic acid pharmacokinetics and adverse effects post-renal transplant, which could be attributed to differences in enterohepatic circulation.

Gut microbiota dysbiosis and diarrhea in kidney transplant recipients

Posttransplant diarrhea is associated with kidney allograft failure and death, but its etiology remains unknown in the majority of cases. Because altered gut microbial ecology is a potential basis for diarrhea, we investigated whether posttransplant diarrhea is associated with gut dysbiosis. We enrolled 71 kidney allograft recipients for serial fecal specimen collections in the first 3 months of transplantation and profiled the gut microbiota using 16S ribosomal RNA (rRNA) gene V4-V5 deep sequencing. The Shannon diversity index was significantly lower in 28 diarrheal fecal specimens from 25 recipients with posttransplant diarrhea than in 112 fecal specimens from 46 recipients without posttransplant diarrhea. We found a lower relative abundance of 13 commensal genera (Benjamini-Hochberg adjusted P ≤ .15) in the diarrheal fecal specimens including the same 4 genera identified in our prior study. The 28 diarrheal fecal specimens were also evaluated by a multiplexed polymerase chain reaction (PCR) assay for 22 bacterial, viral, and protozoan gastrointestinal pathogens, and 26 specimens were negative for infectious etiologies. Using PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) to predict metagenomic functions, we found that diarrheal fecal specimens had a lower abundance of metabolic genes. Our findings suggest that posttransplant diarrhea is not associated with common infectious diarrheal pathogens but with a gut dysbiosis.

Effect of Systematic Conversion to Generic Mycophenolate Mofetil (MMF) in Kidney Transplantation: A Single-Center Clinical Experience from Japan

INTRODUCTION

Recently, more and more generic drugs have been used for immunosuppressive drugs in the field of organ transplantation. Some reports have indicated that blood concentration of most generic drugs is difficult to maintain stability, and it may cause the difference in graft survival of transplanted organs between original drugs and generic drugs. In this article, we report the cases could not maintain blood concentration of generic drugs of mycophenolate mofetil (MMF).

RESULTS

In 4 cases out of 5 cases that we had to change original MMF to generic MMF, there were cases that blood concentration level was not stabilized. There were possibility that the lowered blood concentration level of MMF caused a rejection, in two cases. Mean MMF trough level was decreased from 3.6 ± 1.9 μg/mL to 0.6 ± 0.4 μg/mL. Due to the early detection, it did not become severe or failure of graft function, however, we cannot deny the possibilities that side effects were increased and rejection rose. In these cases, we discontinued to use the generic drugs thereafter due to unstable plasma concentration of MMF.

DISCUSSION

Some reports have indicated that failure to maintain plasma concentration of MMF leads to rejection. Therefore, maintenance of effective plasma concentration and prevention of rejection are essential to long-term graft survival in kidney transplant.

CONCLUSION

Generic drug formulations may exhibit differences in effects and absorption compared to the brand-name drug. If the generic drug should be used, patients should be closely monitored.

Presence of T-275A and C-2152T Polymorphisms of the Promoter Region of Uridine Diphosphate-Glucuronosyltransferase 1A9 Increases Mortality From Digestive Tumors: Results After 10 Years of Follow-up in a Renal Transplant Population

BACKGROUND

The aim of this study was to determine the distribution of uridine diphosphate-glucuronosyltransferase 1A9 (UGT1A9) promoter region T-275A and C-2152T single-nucleotide polymorphisms (SNPs) in stable transplant patients and to investigate the impact of these SNPs on the evolution of this population after 10 years of follow-up.

METHODS

White renal transplant recipients (n = 873) were studied. The median time of follow-up was 91.8 months (P25-75 46-146). Amplification with specific "primers" to delimit the study area was performed for each polymorphism. Amplification was performed with the use of real-time polymerase chain reaction.

RESULTS

T-275A promoter mutation was detected in 13% of patients and C-2152T in 12% of patients. Survival analysis was performed on 873 renal transplants, carried out between 2004 and 2013. We found a higher frequency of death from cancer among polymorphism carriers (P = .001).

CONCLUSIONS

It appears that carriers of T-275A and C-2152T SNPs of the UGT1A9 gene promoter region show a greater incidence of death from cancer, with a significantly higher cumulative incidence of death from gastrointestinal tumors.

The Immunosuppressant Mycophenolic Acid Alters Nucleotide and Lipid Metabolism in an Intestinal Cell Model

The study objective was to elucidate the molecular mechanisms underlying the negative effects of mycophenolic acid (MPA) on human intestinal cells. Effects of MPA exposure and guanosine supplementation on nucleotide concentrations in LS180 cells were assessed using liquid chromatography-mass spectrometry. Proteomics analysis was carried out using stable isotope labeling by amino acids in cell culture combined with gel-based liquid chromatography-mass spectrometry and lipidome analysis using ¹H nuclear magnetic resonance spectroscopy. Despite supplementation, depletion of guanosine nucleotides (p < 0.001 at 24 and 72 h; 5, 100, and 250 μM MPA) and upregulation of uridine and cytidine nucleotides (p < 0.001 at 24 h; 5 μM MPA) occurred after exposure to MPA. MPA significantly altered 35 proteins mainly related to nucleotide-dependent processes and lipid metabolism. Cross-reference with previous studies of MPA-associated protein changes widely corroborated these results, but showed differences that may be model- and/or method-dependent. MPA exposure increased intracellular concentrations of fatty acids, cholesterol, and phosphatidylcholine (p < 0.01 at 72 h; 100 μM MPA) which corresponded to the changes in lipid-metabolizing proteins. MPA affected intracellular nucleotide levels, nucleotide-dependent processes, expression of structural proteins, fatty acid and lipid metabolism in LS180 cells. These changes may compromise intestinal membrane integrity and contribute to gastrointestinal toxicity.

[Immunosuppression and its use in kidney transplantation]

BACKGROUND

Current immunosuppressive protocols effectively prevent acute rejection of renal allografts. Extensive drug toxicity and the deleterious effects of long-term immunosuppression are associated with significant morbidity and mortality.

OBJECTIVES

The purpose of this article is to provide an overview over modern immunosuppressants and their unwanted side effects and to discuss strategies for improved long-term transplant survival.

METHODS

Review of the current topic-related literature and discussion of our own experience.

RESULTS

The use of antibody induction together with an initial combination therapy of calcineurin inhibitors, mycophenolate and steroids is recommended and results in excellent early outcomes. Detrimental effects include an increased incidence of infections, malignomas, and cardiovascular diseases. Long-term transplant survival is impaired by extensive drug toxicity and the frequent development of donor specific antibodies. Reduction of overall cumulative exposure to immunosuppressants or the reduction of specific toxic drugs such as calcineurin inhibitors and steroids may improve long-term results. Alternative immunosuppressants like mTOR inhibitors and belatacept appear to be effective and safe but their long-term effects on patient and allograft survival needs to be established in clinical trials.

CONCLUSIONS

Current immunosuppressants provide effective protection from renal allograft rejection. However, their use is complicated by serious side effects. In the future, development of novel immunosuppressants and optimization of minimization strategies may help to improve long-term success after kidney transplantation.

Routine prophylaxis with proton pump inhibitors and post-transplant complications in kidney transplant recipients undergoing early corticosteroid withdrawal

Surgical stress, corticosteroids, and mycophenolate may contribute to gastrointestinal ulcers/bleeding after kidney transplantation. Prophylactic acid suppression with H2RAs or PPIs is often utilized after transplantation, although unclear if truly indicated after early corticosteroid withdrawal (CSWD). PPIs have been associated with increased risks of Clostridium difficile infection (CDI), pneumonia, and acute rejection. This retrospective cohort study investigated benefits and risks of prolonged PPI use following kidney transplantation and included 286 kidney recipients undergoing CSWD within five d of transplant who were maintained on tacrolimus and mycophenolate mofetil/sodium. Patients on PPI before transplant, H2RA before/after transplant, and/or those with pre-transplant GI complications were excluded. A total of 171 patients received PPI>30 d, mean duration 287 ± 120 d (PPI group); 115 patients were not maintained on acid suppression (No-PPI group). GI ulceration and bleeding events were rare in PPI group (1.2% and 2.3%, respectively) and not observed in No-PPI group (p = NS). The incidence of infectious or hematological complications was not significantly different between groups. The PPI group experienced more biopsy-proven acute rejection (9.4% vs. 2.6%, p = 0.03). No direct benefit was observed with PPI in reducing the incidence of GI ulcers and bleeding events in kidney transplant recipients undergoing early CSWD. Further studies are needed to investigate the association of PPI and acute rejection.

Improvement in Severe Mycophenolic Acid-associated Gastrointestinal Symptoms after Changing Enteric-coated Mycophenolate Sodium to Mizoribine in Renal Transplant Recipients: Two Case Reports

Clinical results point to a better gastrointestinal tolerability with enteric-coated mycophenolate sodium as compared to mycophenolate mofetil. However, some transplant recipients who are treated with enteric-coated mycophenolate sodium still experience gastrointestinal symptoms. We herein present two cases of renal transplant recipients with severe gastrointestinal symptoms who were switched from enteric-coated mycophenolate sodium to mizoribine, and the symptom reversal effects were evaluated using the Gastrointestinal Symptom Rating Scale. The results of this study showed a significant improvement in severe gastrointestinal symptoms in renal transplant recipients after converting from enteric-coated mycophenolate sodium to mizoribine.

Impact of Mycophenolate Mofetil Dose Reduction on Allograft Outcomes in Kidney Transplant Recipients on Tacrolimus-Based Regimens: A Systematic Review

OBJECTIVE

To systematically evaluate the clinical consequences of mycophenolate dose reduction in renal transplant recipients on tacrolimus-based regimens.

DATA SOURCES

PubMed (1949-July 2010), EMBASE (1980-July 2010), Cochrane Database of Systematic Reviews, International Pharmaceutical Abstracts, and Web of Science were searched using the terms mycophenolate mofetil, tacrolimus, dose reduction, and kidney and/or renal transplant. References from publications identified were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Studies reporting on rejection rate, allograft survival, or renal function were included and ranked according to the US Preventive Services Task Force classification; excluded were studies that were dose-finding or used cyclosporine only, involved patients on enteric-coated mycophenolate sodium or those with multiorgan transplant, or provided no information on concomitant immunosuppressants. Data extracted were study design, sample size, immunosuppression regimen, type of transplant, and allograft outcomes.

DATA SYNTHESIS

Of 13 studies included, 1 was level I evidence, 3 were level II-2, 6 were level II-3, and 3 were level III evidence. Three focused on tacrolimus-based regimens, whereas 7 included either cyclosporine or tacrolimus. The only prospective, randomized, multicenter trial demonstrated that early taper of mycophenolate dosage to 1 g/day can be utilized without increased risk of rejection, compared with late tapering, but the rejection rate was high (30-40%). Overall, we found conflicting evidence regarding the impact of mycophenolate dose reduction on rejection rate and allograft loss and that discontinuing mycophenolate led to an increased risk of graft loss as high as 8 fold. Allograft survival was lowest in patients with gastrointestinal complications and those in whom mycophenolate was discontinued, compared with patients with neither gastrointestinal complications nor mycophenolate discontinuation.

CONCLUSIONS

Weak evidence suggests that mycophenolate dose modifications, either reduction or discontinuation, may increase rejection rate and graft loss; however, this is more apparent in cyclosporine-based regimens. Prospective, well-designed trials are necessary to definitively determine the impact of dose reduction in renal transplant recipients on tacrolimus-based regimens.

Enteric-coated mycophenolate sodium given in combination with tacrolimus has a lower incidence of serious infections in Asian renal-transplant recipients compared with mycophenolate mofetil

AIMS

To compare the characteristics of the enteric-coated formulation of mycophenolate sodium (EC-MPS, myfortic) and mycophenolate mofetil (MMF, CellCept) given in combination with tacrolimus in Asian renal-transplant recipients.

METHODS

In a 24-month, single-centre, randomized, open-label, prospective study, 101 live-donor kidney transplant recipients were randomized to the EC-MPS (n = 50) or MMF (n = 51) group. The incidence of infection, therapeutic effect and adverse events were monitored.

RESULTS

The incidences of infection were 40% and 49% for the EC-MPS and MMF groups, respectively (p = 0.362). However, serious infection was only observed in the MMF group (11.8%; p = 0.027). The incidences of gastro-intestinal adverse events (GI AEs) were 24% and 41.2% for EC-MPS and MMF, respectively (p = 0.066). However, serious diarrhoea only occurred in the MMF group (9.8%; p = 0.056). The trough level of FK 506 at the time of diarrhoea (13.22 ± 3.66 ng/ml) was significantly higher than the level within 1 month before (9.18 ± 1.12 ng/ml; p < 0.05) and 1 month after diarrhoea (9.13 ± 0.85 ng/ml; p < 0.05). The infection rate of patients with diarrhoea was significantly higher than those without diarrhoea (68%, 39%, p = 0.024). The serum creatinine level was 698 ± 60 μmol/l for EC-MPS and 673 ± 68 μmol/l for MMF from baseline (p > 0.05), and it decreased to 66 ± 6 μmol/l for EC-MPS and 69 ± 8 μmol/l for MMF at 24 months (p > 0.05). The incidences of biopsy proven acute rejection (BPAR) were 20% and 25.5% for EC-MPS and MMF, respectively (p = 0.511).

CONCLUSIONS

Enteric-coated formulation of mycophenolate sodium, given in combination with tacrolimus, has a lower incidence of serious infection in Asian renal-transplant recipients compared with MMF, and the therapeutic effect of EC-MPS is similar to MMF. The clinical trial registration number is ChiCTR-IPR-14005509. The registry name is 'Effect of Enteric-coated mycophenolate sodium on posttransplant infection rate after renal transplantation compared with Mycophenolate mofetil'.

Bone marrow suppression and associated consequences in patients after heart transplantation: A 6-year retrospective review

AIMS

To evaluate the incidence of bone marrow suppression and consequences of MMF dose adjustment in patients within the first year after heart transplantation.

METHODS

Group I (n=47) was treated with a regimen currently used in patients after heart transplantation (mycophenolatemofetil - MMF, valganciclovir - VGC and trimethoprim/sulfamethoxazole - TMP-SMX). Group II (n=47) received only MMF of potentially myelotoxic medications. The myelotoxic effect and need for dose modification were assessed. The incidence of rejections and infectious episodes associated with MMF adjustment were analyzed during the first 12 months in Group I.

RESULTS

There was a significantly greater proportion of patients with leukopenia (leukocyte count < 4 x 10^9/L) at 3 months after orthotopic heart transplantation in Group I compared with Group II (19.1% vs 2.1%; P = 0.02). The difference in lymphopenia (lymphocyte count < 0.8 x 10^9/L) at 3 months follow-up was highly significant (38.3 % vs 6.4 %; P = 0.0002). MMF was modified due to bone marrow suppression or severe infection in 63.8% patients in Group I and in only 8.5% of patients in Group II (P < 0.001). Reducing or stopping MMF was not associated with increased rejections. In Group I, at least 1 episode of higher degree cellular or humoral rejection occurred in 35% of patients with the standard MMF dosage compared with only 26% in patients with modified MMF (P = 0.0534).

CONCLUSIONS

Addition of VGC+TMP-SMX to current immunosuppressive medication regimen in patients after heart transplantation is associated with significant lymphocytopenia and leukopenia. Importantly, modification of immunosuppressive prophylaxis (reducing or stopping MMF) leads to normalization of blood count without increased incidence of rejections.

A single-centre, open-label, prospective study of an initially short-term intensified dosing regimen of enteric-coated mycophenolate sodium with reduced cyclosporine A exposure in Chinese live-donor kidney transplant recipients

AIMS

The nephrotoxicity of cyclosporine A (CsA) accounts for dysfunction of kidney allografts in the clinic. Short-term intensified dosing using enteric-coated mycophenolate sodium (EC-MPS) may facilitate CsA sparing after kidney transplantation without compromising safety.

METHODS

In a 12-month, single-centre open-label prospective trial, 180 de novo live-donor kidney transplant recipients at low-immunological risk were randomised to a low-dose cyclosporine group which received a low dose of cyclosporine, short-term intensified EC-MPS dosing (2160 mg/day to week 6, 1440 mg/day thereafter) and corticosteroids or a standard-dose cyclosporine group which received a standard dose of cyclosporine, standard EC-MPS dosing (1440 mg/day) and corticosteroids. The primary end-point [treatment failure including biopsy-proven acute rejection (BPAR), graft loss, death], secondary end-point and adverse events were monitored.

RESULTS

The primary end-point (treatment failure) occurred in 13.3% (12/90) of the low-dose cyclosporine group and 16.7% (15/90) of the standard-dose cyclosporine group (p = 0.53) (difference -3.4%, 95% confidence interval -11.7% to 7.5%, based on a noninferiority margin of 20%). BPAR occurred in 11.1% and 13.3% of patients in the low-dose cyclosporine group and standard-dose cyclosporine group, respectively (p = 0.65). The estimated glomerular filtration rate, as calculated by the Cockcroft-Gault formula, was similar at 12 months after transplantation (low-dose cyclosporine group 63 ± 19 ml/min/1.73 m(2) and standard-dose cyclosporine group 59 ± 15 ml/min/1.73 m(2) ; p = 0.43). The levels of serum creatinine and occurrence of adverse events between the two groups were not statistically different.

CONCLUSIONS

A regimen of early intensified EC-MPS dosing permits low-dose cyclosporine in live-donor kidney transplant patients at low-immunological risk without compromising efficacy at 12 months' follow-up.

Gut microbial community structure and complications after kidney transplantation: a pilot study

BACKGROUND

The gut microbiome plays a role in the regulation of the immune system.

METHODS

We prospectively enrolled 26 kidney transplant recipients and collected serial fecal specimens (N=85) during the first three months of transplantation. We characterized bacterial composition by polymerase chain reaction amplification of the 16S rRNA V4-V5 variable region and deep sequencing using the Illumina MiSeq platform.

RESULTS

An increase in the relative abundance of Proteobacteria was observed in the posttransplantation specimens compared to pretransplantation specimens (P=0.04, Wilcoxon signed-rank test). In patients with posttransplant diarrhea, the mean(±standard deviation [SD]) Shannon diversity index was lower in those with diarrhea (N=6) than those without diarrhea (N=9) (2.5±0.3 vs. 3.4±0.8; P = 0.02, Wilcoxon rank-sum test). Principal coordinate analysis showed clear separation between the two groups, and linear discriminant analysis effect size (LEfSe) method revealed that Bacteroides, Ruminococcus, Coprococcus, and Dorea were significantly lower in the patients with diarrhea. Principal coordinate analysis also showed clear separation between the acute rejection (AR) group (N=3) and the no AR group (N=23) and the LEfSe method revealed significant differences between the two groups. Fecal abundance of Enterococcus was associated with Enterococcus urinary tract infection (UTI). The median Enterococcus fecal abundance was 24% (range, 8%-95%) in the three patients with Enterococcus UTI compared to 0% in the 23 patients without Enterococcus UTI (interquartile range, 0.00%-0.08%) (P=0.005, Wilcoxon rank-sum test).

CONCLUSION

Our pilot study identified significant alterations in the gut microbiota after kidney transplantation. Moreover, distinct microbiota structures were observed in allograft recipients with posttransplant diarrhea, AR, and Enterococcus UTI.

Tacrolimus and mycophenolate mofetil associations

Gastrointestinal risk factors after organ transplantation are prevalent, due to the chronic use of immunosuppressant. The immunosuppressive drugs such as tacrolimus/mycophenolate mofetil (TAC/MMF) association are the most commonly used therapy. TAC and MMF have been implicated in gastrotoxicity, but their direct effects, alone and combined, on intestinal cells are not completely elucidated. This study investigated the effect of TAC and MMF alone and combined on human colon carcinoma cells. Our results demonstrated that TAC and MMF individually inhibit clearly cells proliferation, enhanced free radicals, lipid peroxidation production, induced DNA lesions and reduced mitochondrial membrane potential. In this study, we also showed that the two molecules TAC and MMF combined at high concentrations amplified the cell damage. Furthermore, the TAC (5 µM) prevented cell death induced by MMF (half maximal inhibitory concentration (IC50)). Also, MMF (50 µM) induced cytoprotection in HCT116 cells against TAC (IC50) toxicity. Our findings provide additional evidence that oxidative damage is the major contribution of TAC and MMF combined toxicities. In fact, MMF and TAC exert a gastroprotective effect by modulating reactive oxygen species production. These data underscore the pleiotropic effect of TAC and MMF on HCT116 cells that play a preventive and critical role on intestinal function.

Improvement in gastrointestinal and health-related quality of life outcomes after conversion from mycophenolate mofetil to enteric-coated mycophenolate sodium in liver transplant recipients

OBJECTIVE

To evaluate improvement in gastrointestinal (GI) symptoms and health-related quality of life (HRQoL) in liver transplant recipients switched from mycophenolate mofetil (MMF) to enteric-coated mycophenolate sodium (EC-MPS).

METHODS

A multicenter, open-label, single-arm study was undertaken in maintenance liver transplant recipients who reported GI complications with MMF therapy. The patients were switched to equimolar doses of EC-MPS at baseline. The primary end point was the change in the Gastrointestinal Symptom Rating Scale (GSRS) total score after 6 to 8 weeks of treatment with EC-MPS. Other key assessments for GI symptoms and HRQoL included the GSRS subscores, the Gastrointestinal Quality of Life Index (GIQLI), the Psychological General Well-Being Index, and the Overall Treatment Effect (OTE). Paired t-test was used to assess the difference in the mean score changes over time.

RESULTS

A total of 34 patients were enrolled and switched to equimolar doses of EC-MPS. After 6 to 8 weeks of EC-MPS treatment, mean GSRS total score improved significantly from 2.88 ± 0.66 to 2.10 ± 0.78. Mean improvement in GSRS total score (-0.77 score points; P = .001) exceeded the minimal clinically important difference. Significant improvements were observed in all GSRS subscales (P < .05), GIQLI total scores (P = .001), and GIQLI subscales "GI symptoms" (P < .001) and "physical function" (0.013). Patients who continued EC-MPS reported sustained benefits compared with patients who switched back to MMF after 6 to 8 weeks of treatment with EC-MPS. On the OTE scale, improvement in symptoms was reported in 76.5% and 61.8% of the patients as perceived by the physicians and the patients. Improvement in HRQoL was reported by 41.2% of the patients. No deaths, biopsy proven acute rejections, or graft losses were reported during the study.

CONCLUSION

Conversion from MMF to EC-MPS was associated with a significant improvement in GI symptoms and HRQoL in liver transplant recipients.

Evaluating the impact of gastrointestinal episodes on the health-related quality of life of solid organ transplant recipients: sensitivity to change of the SIGIT-QoL questionnaire: Mypaciente-2 study

A significant proportion of transplant patients undergoing immunosuppressant therapy experience gastrointestinal (GI) symptoms. The SIGIT-QoL is a brief instrument developed to measure adverse gastrointestinal effects on patients' health-related quality of life (HRQoL). The goal of this study was to analyze the psychometric properties of the SIGIT-QoL that are required for its use in clinical research and practice, especially its value for detecting changes in the impact of gastrointestinal symptoms on HRQoL of solid organ transplant (SOT) recipients. To this end, an observational, multicenter, prospective study was conducted. SOT patients aged ≥18 years who had received the graft 3 to 24 months before and were experiencing gastrointestinal symptoms were evaluated at baseline, 1 to 2 weeks later, and 3 months after baseline. Sociodemographic and clinical data recorded included: age, sex, SOT type (lung, kidney, liver, or heart), acute allograft rejection, gastrointestinal etiology, Clinical Global Impressions (CGI) and Patient Global Impression (PGI) Severity of Illness (SI) and Global Improvement (GI) scores, and the SIGIT-QoL (scores range from 0 [maximum impact] to 68 [minimum disruption]). Intraclass correlation coefficients, differences between baseline and last visit (Wilcoxon test), effect size (Cohen's d), the minimal important differences (using CGI and PGI scores as anchors in General Linear Models), and the cutoff score (receiver-operating characteristic analysis) were calculated. In total, 277 SOT patients (61.4% male) were included. Mean ± SD age was 52.69 ± 11.65 years, time since transplantation was 12.31 ± 6.74 months, and 22.4% experienced an acute allograft rejection. At baseline, total SIGIT-QoL mean scores (51.21 ± 11.25) showed an impact on patients' HRQoL that was diminished 3 months later (57.40 ± 8.38; P < .001). SIGIT-QoL test-retest reliability was adequate (intraclass correlation coefficient, 0.740-0.895). A moderate effect size (d = -0.550) was found. Moreover, a minimal important difference of 4.2 points in total scores was found (F4,223 = 16.917 [P < .001] and F4,224 = 25.138 [P < .001]). Finally, a cutoff point (55.00 points) was estimated (area under the concentration-time curve, 0.846 [95% confidence interval, 0.798-0.894], P < .001; sensitivity, 0.793; specificity, 0.713; negative likelihood ratio, 0.290; positive likelihood ratio, 2.762). We concluded that the SIGIT-QoL is a feasible (average completion time, <6.5 minutes), reliable, and valid instrument for assessing the impact of gastrointestinal symptoms on the HRQoL of SOT patients.

Diarrhea after kidney transplantation: a new look at a frequent symptom

Diarrhea is a frequent but overlooked complication of kidney transplantation. Diarrhea is repeatedly neglected, often considered by patients and clinicians an unavoidable side effect of immunosuppressive regimens. It is, however, associated with a significant impairment in life quality. Severe and chronic posttransplant diarrhea may lead to dehydration, malabsorption, rehospitalization, immunosuppression, noncompliance, and a greater risk of graft loss and death. There is thus a need to optimize and standardize the management of posttransplant diarrhea with consistent diagnostic and therapeutic strategies. A recent study has suggested that the increased sensitivity of molecular tools might help in early pathogen identification and guidance of antimicrobial treatment. Most bacterial and protozoan infections are readily curable with appropriate antimicrobial agents; cryptosporidiosis and C. difficile infections may however be complicated by relapsing courses. In addition, identification of enteric viral genomes in stool has further reduced posttransplant diarrhea of unknown origin. Chronic norovirus-related posttransplant diarrhea, arising from the interplay of the virus and immunosuppressive drugs, has emerged as a new challenge in the field. Prospective and controlled studies are necessary to evaluate the efficacy and safety of innovative anti-norovirus therapeutics, as well as optimal immunosuppressive regimens, to enable viral clearance while preventing rejection and donor-specific antibody formation. This review seeks to provide a basis for the design of future clinical prospective studies.

Diagnostic yields in solid organ transplant recipients admitted with diarrhea

BACKGROUND

Although diarrhea is a frequent complaint among solid organ transplant recipients, the contribution of infectious etiologies remains incompletely defined. We sought to define the etiologies of diarrhea and the yields of testing at our institution.

METHODS

We performed a retrospective analysis over an 18-month period of hospitalized solid organ transplant recipients. We stratified diarrhea by community onset vs hospital onset of diarrhea.

RESULTS

We identified 422 admissions (representing 314 unique patients) with community-onset diarrhea, and 112 admissions (representing 102 unique patients) with hospital-onset diarrhea. The majority of community- and hospital-onset diarrheal episodes had no identified etiology (60.9% and 75.9%, respectively; P = .03), yet were also self-limited (91% and 91%, respectively; P = .894). Thereafter, the most frequently encountered infectious etiologies were Clostridium difficile infection (13.3% and 11.8%, respectively), norovirus enteritis (8.2% and 3%), cytomegalovirus disease or colitis (6.3% and 2.7%), and bacterial enterocolitis (0.9% and 0%) (P = .03). In aggregate, these entities represented 93.7% and 90.5% of the identified infectious etiologies, respectively. Protozoan causes were rarely seen. Coinfection, or the simultaneous detection of ≥2 pathogens, occurred in 8 (1.9%) and 2 (1.8%) community- and hospital-onset diarrheal admissions, respectively (P = .99).

CONCLUSIONS

In solid organ transplant recipients who presented at our institution with diarrhea, approximately one-third had infectious etiologies identified, consisting predominantly of C. difficile, norovirus, cytomegalovirus, and bacterial enterocolitis. Other infectious etiologies were rare.

Changes in the small bowel of symptomatic kidney transplant recipients converted from mycophenolate mofetil to enteric-coated mycophenolate sodium

BACKGROUND/AIMS

Gastrointestinal (GI) symptoms in renal transplant recipients may be caused due to mycophenolic acid (MPA) toxicity. Using small bowel capsule endoscopy (SBCE) we examined the impact of conversion from Mycophenolate Mofetil (MMF) to enteric-coated formulation of Mycophenolate Sodium (EC-MPS) given to treat GI mucosal lesions.

METHODS

Adult kidney-only recipients at least 30 days after transplant, presenting with GI symptoms while receiving MMF completed a Gastrointestinal Symptom Rating Scale (GSRS) questionnaire, underwent SBCE, and had MMF substituted by EC-MPS. After 30 days, GSRS and SBCE were repeated and findings were compared to baseline values. Patients who were still on EC-MPS 6-24 months post-conversion were contacted for completing a follow-up GSRS questionnaire and SBCE.

RESULTS

Eighteen out of 23 subjects completed the first part of the study. Subjects' median ages and post-transplant time were 47.5 years old and 4.5 months, respectively. Tacrolimus, MMF and prednisone was the main regimen (94%), with a median MMF dose of 750 mg BID. The average baseline GSRS was 2.99 ± 0.81; it significantly decreased to 2.19 ± 0.8 at 30 days post-conversion. At baseline, 50 had gastric and 89% had small bowel lesions. At 30 days, 29 and 62% of the SBCE were still showing gastric and small bowel lesions, respectively. Of 5 patients in the study extension, 4 had abnormal SBCE findings but have been reporting improvement in their symptoms.

CONCLUSION

Stomach and small bowel mucosal lesions are common in kidney recipients with GI symptoms when treated with MMF. Conversion to EC-MPS for 30 days significantly alleviated the GI symptoms; however, no evident correlation with SBCE findings was found.

Long-term dosing patterns of enteric-coated mycophenolate sodium or mycophenolate mofetil with tacrolimus after renal transplantation

MORE was a four-yr, prospective, observational study at 40 transplant centers in the US. Data were analyzed to evaluate changes in mycophenolic acid (MPA) dosing over time in 904 de novo kidney transplant recipients receiving enteric-coated mycophenolate sodium (EC-MPS, n = 616) or mycophenolate mofetil (MMF, n = 288) with tacrolimus. Induction therapy and steroid treatment were similar in the two subpopulations. The proportion of patients receiving the maximal recommended MPA dose was 80.5%, 43.9%, 39.2%, 34.6%, and 30.1% at baseline and years 1, 2, 3, and 4, respectively. More patients received the maximal recommended MPA dose with EC-MPS vs. MMF at month 1 (79.2% vs. 71.7%, p = 0.016), month 3 (68.5% vs. 56.9%, p = 0.001), and month 6 (52.9% vs. 44.0%, p = 0.028). Multivariate analysis showed the risk of biopsy-proven acute rejection, graft loss or death to be similar for EC-MPS vs. MMF. Estimated glomerular filtration rate (GFR) was similar with EC-MPS vs. MMF at all time points. There were no significant differences in any category of adverse event between the EC-MPS and MMF cohorts during follow-up, including gastrointestinal events. In conclusion, MPA dose was maintained more effectively in the first six months after kidney transplantation using EC-MPS vs. MMF, without an increase in adverse events.

Concomitant proton pump inhibitors with mycophenolate mofetil and the risk of rejection in kidney transplant recipients

BACKGROUND

Recent pharmacokinetic studies have demonstrated that proton pump inhibitors (PPI) reduce exposure of mycophenolic acid. However, the clinical significance of this drug-drug interaction on transplantation outcomes has not been determined.

METHODS

This was a retrospective cohort study in kidney transplant recipients who were prescribed rabbit antithymocyte globulin, calcineurin inhibitor, mycophenolate mofetil, and steroids. We evaluated the impact of PPI use on the 1-year rates of biopsy-proven acute rejection (BPAR).

RESULTS

Two hundred thirteen patients who were prescribed PPI were compared with 384 patients who were on standard acid-suppressive therapy with ranitidine. BPAR occurred in similar rates in both groups (15% vs. 12%; P=0.31). In a multivariable analysis, black race was associated with a higher risk of rejection (risk ratio [RR], 2.38; 95% confidence interval [CI], 1.41-4.03). While controlling for rejection risk factors, PPI exposure was associated with an increased risk of rejection in black patients (RR, 1.93; 95% CI, 1.18-3.16) but not in non-black patients (RR, 0.54; 95% CI, 0.19-1.49). At 1 year, BPAR type, BPAR grade, patient and graft survival, graft function, and time to BPAR were not associated with PPI exposure.

CONCLUSION

In this retrospective study, PPI use in the first transplant year was associated with an increased risk for BPAR in black patients but not in non-black patients. It is possible that a reduction in mycophenolic acid exposure contributed to the increased risk.

Multi-institutional Study of Outcomes After Pediatric Heart Transplantation: Candidate Gene Polymorphism Analysis of ABCC2

OBJECTIVES

Earlier studies have indicated that the pharmacokinetics of mycophenolic acid (MPA) is influenced by polymorphisms of ABCC2, which encodes for the membrane transporter MRP2. The ABCC2 rs717620 A allele has been associated with enterohepatic recirculation of MPA, and our previous work had correlated the discontinuance of MPA with this allele in pediatric heart transplant patients. Therefore, we hypothesized that the ABCC2 rs717620 A allele would be associated with poorer outcomes including rejection with hemodynamic compromise (RHC), graft failure, and death in the pediatric heart transplant (PHTx) population receiving MPA.

METHODS

PHTx recipients from 6 institutions in the Pediatric Heart Transplantation Study (PHTS) from the period of 1993-2009, receiving MPA therapy, were genotyped for ABCC2 rs717620. Genotyping was accomplished by direct sequencing. Demographic and outcome data were limited to the data routinely collected as part of the PHTS and included RHC and mortality.

RESULTS

Two hundred ninety patients were identified who received MPA at some point post transplantation, of which 200 carried the GG genotype, 81 carried the AG genotype, and 9 carried the AA genotype. Follow-up time after transplantation was 6 years. RHC occurred in 76 patients and 18 patients died. In the 281 patients followed up more than 1 year, late RHC (>1 year post transplantation) occurred in 42 patients. While both RHC and late RHC were associated with the ABCC2 rs717620 GG genotype (hazard ratios: 1.80 and 4.57, respectively, p<0.05) in all patients, this association was not significant in PHTx patients receiving only MPA as the antiproliferative agent from the time of transplant (n=142).

CONCLUSIONS

ABCC2 rs717620 polymorphisms varied within racial groups. As a candidate gene assessment, the ABCC2 rs717620 AG and AA genotypes may be associated with improved, rather than poorer, RHC in PHTx patients receiving MPA therapy. ABCC2 rs717620 polymorphisms should be included in any expanded pharmacogenomic analysis of outcomes after pediatric heart transplantation.