Erosive enterocolitis in mycophenolate mofetil-treated renal-transplant recipients with persistent afebrile diarrhea

The Importance of the FUT2 rs602662 Polymorphism in the Risk of Cardiovascular Complications in Patients after Kidney Transplantation

The FUT2 gene encodes an enzyme called α-1,2-fucosyltransferase, which is involved in the formation of blood group antigens AB0(H) and is also involved in the processes of vitamin B12 absorption and its transport between cells. FUT2 gene polymorphisms are associated with vitamin B12 levels in the body. Vitamin B12 deficiency associated with hyperhomocysteinemia is a major risk factor for cardiovascular diseases (CVDs), which are one of the main causes of death in patients after kidney transplantation. The aim of our study was to determine the impact of the rs602662 (G>A) polymorphism of the FUT2 gene on the functionality of transplanted kidneys and the risk of CVD in patients after kidney transplantation. The study included 402 patients treated with immunosuppression (183 patients taking cyclosporine (CsA) and 219 patients taking tacrolimus (TAC)). The analysis of the FUT2 rs602662 (G>A) polymorphism was performed using real-time PCR. Patients with CsA were more likely to be underweight (1.64% vs. 0.91%) and obese (27.87% vs. 15.98%), while those taking TAC were more likely to be of normal weight (39.27%) or overweight (43.84%). No statistically significant differences were observed comparing the mean blood pressure, both systolic and diastolic. The renal profile showed a higher median urea nitrogen concentration in patients with CsA (26.45 mg/dL (20.60-35.40) vs. 22.95 mg/dL (17.60-33.30), p = 0.004). The observed frequency of rs602662 alleles of the FUT2 gene was similar in the analyzed groups. The A allele was present in 43.7% of patients with CsA and 41.1% of those taking TAC (OR = 0.898; 95% CI: 0.678-1.189; p = 0.453). In the group with CsA, the GG genotype was present in 32.2% of patients, the GA in 48.1% and the AA in 19.7%. A similar distribution was obtained in the TAC group: GG-33.8%, GA-50.2%, and AA-16.0%. An association of genotypes containing the G allele with a higher incidence of hypertension was observed. The G allele was present in 65% of people with hypertension and in 56% of patients with normal blood pressure (p = 0.036). Moreover, the evaluation of the renal parameters showed no effect of the FUT2 polymorphism on the risk of organ rejection because the levels of creatinine, eGFR, potassium, and urea nitrogen were prognostic of successful transplantation. Our results suggest that the rs6022662 FUT2 polymorphism may influence the risk of cardiovascular diseases.

An open-label randomised-controlled trial of azathioprine vs. mycophenolate mofetil for the induction of remission in treatment-naive autoimmune hepatitis

BACKGROUND & AIMS

Patients with autoimmune hepatitis (AIH) almost invariably require lifelong immunosuppressive treatment. There is genuine concern about the efficacy and tolerability of the current standard combination therapy of prednisolone and azathioprine. Mycophenolate mofetil (MMF) has emerged as an alternative option. The aim of this study was to compare MMF to azathioprine as induction therapy for AIH.

METHODS

In this 24-week, prospective, randomised, open-label, multicentre superiority trial, 70 patients with treatment-naive AIH received either MMF or azathioprine, both in combination with prednisolone. The primary endpoint was biochemical remission defined as normalisation of serum levels of alanine aminotransferase and IgG after 24 weeks of treatment. Secondary endpoints included safety and tolerability.

RESULTS

Seventy patients (mean 57.9 years [SD 14.0]; 72.9% female) were randomly assigned to the MMF plus prednisolone (n = 39) or azathioprine plus prednisolone (n = 31) group. The primary endpoint was met in 56.4% and 29.0% of patients assigned to the MMF group and the azathioprine group, respectively (difference, 27.4 percentage points; 95% CI 4.0 to 46.7; p = 0.022). The MMF group exhibited higher complete biochemical response rates at 6 months (72.2% vs. 32.3%; p = 0.004). No serious adverse events occurred in patients who received MMF (0%) but serious adverse events were reported in four patients who received azathioprine (12.9%) (p = 0.034). Two patients in the MMF group (5.1%) and eight patients in the azathioprine group (25.8%) discontinued treatment owing to adverse events or serious adverse events (p = 0.018).

CONCLUSIONS

In patients with treatment-naive AIH, MMF with prednisolone led to a significantly higher rate of biochemical remission at 24 weeks compared to azathioprine combined with prednisolone. Azathioprine use was associated with more (serious) adverse events leading to cessation of treatment, suggesting superior tolerability of MMF.

IMPACT AND IMPLICATIONS

This randomised-controlled trial directly compares azathioprine and mycophenolate mofetil, both in combination with prednisolone, for the induction of biochemical remission in treatment-naive patients with autoimmune hepatitis. Achieving complete remission is desirable to prevent disease progression. Patients assigned to the mycophenolate mofetil group reached biochemical remission more often and experienced fewer adverse events. The findings in this trial may contribute to the re-evaluation of international guidelines for the standard of care in treatment-naive patients with autoimmune hepatitis.

TRIAL REGISTRATION NUMBER

#NCT02900443.

Tacrolimus-Associated Terminal Ileitis After Kidney Transplantation, Mimicking Crohn Disease: A Case Report

The onset of gastroduodenal ulcers is a frequent complication after transplantation, whereas cases of intestinal ulcers are sporadic and poorly described in the literature. A patient on immunosuppressive therapy with tacrolimus and mycophenolate mofetil after kidney transplant for immunoglobulin A-related glomerulonephritis developed symptoms compatible with Crohn disease 7 months after the transplant. The patient was hospitalized for abdominal pain, diarrhea, fever, and weight loss. Imaging and a colonoscopy showed signs of idiopathic inflammatory bowel disease (IBD) affecting the terminal ileum. Behcet's disease, post-transplant lymphoma, cytomegalovirus, Epstein-Barr virus, or mycobacteria infection were excluded. Mycophenolate mofetil was suspended, and steroid therapy was increased without clinical improvement. Eleven units of blood were required for severe anemia. A further colonoscopy revealed ulcerations involving the cecal fundus, ileocecal valve, and distal ileum with bowel stenosis and suspected ischemia. The patient, therefore, underwent an emergency laparoscopic ileocolic resection. The histologic examination did not reveal clear signs of IBD, ischemia, or viral infection of the ileum. The findings seemed indicative of iatrogenic damage from immunosuppressive therapy. The postoperative course was regular, and after 12 months, the patient was asymptomatic, on low-dose tacrolimus and prednisone therapy. During immunosuppressive therapy, the onset of isolated ileal ulcers, which can mimic IBD, may be a sporadic complication.

Celiac-Like Duodenopathy Associated With Enteric-Coated Mycophenolate Sodium Immunosuppression in Renal Transplant Recipients: Report of 4 Cases

Celiac-like disease and celiac sprue associated with widespread use of mycophenolic acid are among the most frequent complications of renal transplant. Most cases have been observed in patients receiving mycophenolate mofetil; however, there have been rare instance after administration of enteric-coated mycophenolate sodium. Here, we describe 4 renal transplant recipients with celiac-like duodenopathy that occurred in association with enteric-coated mycophenolate sodium treatment in a time period of 14 to 19 years after living donor kidney transplant. Three of 4 patients had diarrhea, and all 4 patients had marked loss of body weight. Esophago-gastroduodenoscopy was not diagnostically helpful; however, randomly performed duodenal biopsies showed mild villous atrophy and intraepithelial lymphocytosis. Replacement of enteric-coated mycophenolate sodium with azathioprine was successful with stopping diarrhea, allowing regained body weight, and stabilization of renal function. This potential complication in kidney transplant recipients can occur more than a decade after transplant. Diagnosis and treatment initiation are urgent to cure this disease.

Gastrointestinal injury induced by immunomodulators: A review article

An increasing number of immunomodulators, either anti-inflammatory or immunity-enhancing, have brought about a revolutionary effect in the management of a variety of autoimmune disorders and malignancies. However, their ability to cause gastrointestinal (GI) injury and induce GI symptoms has been increasingly and unexpectedly recognized. GI injury associated with immunomodulators may demonstrate various histologic and endoscopic patterns. Optimal diagnosis and treatment require a multidisciplinary approach. This review aims to provide an overview of the literature on its pathogenesis, the clinical, endoscopic, and histologic features, and suggested approaches to manage these newly recognized immunomodulator-induced GI adverse effects (AEs). We also reviewed current biomarkers predictive of GI toxicity and potential risk factors to identify susceptible patients. In addition, these immune-mediated AEs were compared with inflammatory bowel disease, a well-documented form of inflammation-driven GI injury. We hope this review will raise awareness and vigilance among clinicians of these entities to increase early diagnosis and rapid referral to specialist care.

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.

Unusual Ileocecal Ulcers after Liver Transplantation for Hepatitis B Cirrhosis and Hepatocellular Carcinoma

We presented a case demonstrating ileocecal ulcers after liver transplantation for hepatitis B cirrhosis and hepatocellular carcinoma. The patient presented 4 years post-transplant with paroxysmal right lower abdominal pain. Due to a mild increase in the leukocyte and neutrophil count, infectious diseases were initially suspected. However, probiotic treatment did not help improve the symptom. An enhanced CT scan revealed a thickening in the ileocecal region, and endoscopy later showed multiple giant and deep ulcers in the ileocecal region with polypoid hyperplasia. Histopathology of an ulcer biopsy displayed benign ulcers, and chronic inflammation with non-caseous granulomas, without signs of a fungus or parasite infection. Epithelial exfoliation with atypical hyperplasia was observed, and a tacrolimus-induced ileocecal ulcer was considered by a pathologist. Clinical manifestation, lab findings, radiology, and pathology characteristics of ulcers were not consistent with the pathogenesis of ischemia, tuberculosis, CMV, EBV, tumor, or inflammatory bowel diseases. Abdominal pain was gradually relieved and subsided with the discontinuation of tacrolimus and corticosteroid administration.

The role of gut microbial β-glucuronidase in drug disposition and development

Gut microbial β-glucuronidase (gmGUS) is involved in the disposition of many endogenous and exogenous compounds. Preclinical studies have shown that inhibiting gmGUS activity affects drug disposition, resulting in reduced toxicity in the gastrointestinal tract (GIT) and enhanced systemic efficacy. Additionally, manipulating gmGUS activity is expected to be effective in preventing/treating local or systemic diseases. Although results from animal studies are promising, challenges remain in developing drugs by targeting gmGUS. Here, we review the role of gmGUS in host health under physiological and pathological conditions, the impact of gmGUS on the disposition of phenolic compounds, models used to study gmGUS activity, and the perspectives and challenges in developing drugs by targeting gmGUS.

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.

Gut inflammation induced by drugs: Can pathology help to differentiate from inflammatory bowel disease?

Drug‐induced mucosal injury (DIMI) in the gastrointestinal tract is important to recognise, partly because cessation of the culprit agent alone may result in resolution of symptoms. An ever‐growing list of medications, including newer immunotherapeutic agents and targeted therapies, can cause gastrointestinal inflammation of varying severity. However, the diagnosis of DIMI is challenging, as a single drug can induce a variety of histopathological patterns of injury including acute colitis, chronic colitis, microscopic colitis, apoptotic colopathy, and ischaemic‐type colitis. An additional consideration is the potential clinical, endoscopic and histological overlap of DIMI with gastrointestinal mucosal injury secondary to other entities such as inflammatory bowel disease (IBD). We discuss DIMI of the gastrointestinal tract with an emphasis on histological patterns that mimic IBD, histological features which may distinguish the two entities, and the diagnostic role and limitations of the pathologist.

Influence of immunomodulatory drugs on the gut microbiota

Immunomodulatory medications are a mainstay of treatment for autoimmune diseases and malignancies. In addition to their direct effects on immune cells, these medications also impact the gut microbiota. Drug-induced shifts in commensal microbes can lead to indirect but important changes in the immune response. We performed a comprehensive literature search focusing on immunotherapy/microbe interactions. Immunotherapies were categorized into 5 subtypes based on their mechanisms of action: cell trafficking inhibitors, immune checkpoint inhibitors, immunomodulators, antiproliferative drugs, and inflammatory cytokine inhibitors. Although no consistent relationships were observed between types of immunotherapy and microbiota, most immunotherapies were associated with shifts in specific colonizing bacterial taxa. The relationships between colonizing microbes and drug efficacy were not well-studied for autoimmune diseases. In contrast, the efficacy of immune checkpoint inhibitors for cancer was tied to the baseline composition of the gut microbiota. There was a paucity of high-quality data; existing data were generated using heterogeneous sampling and analytic techniques, and most studies involved small numbers of participants. Further work is needed to elucidate the extent and clinical significance of immunotherapy effects on the human microbiome.

Diarrhea in the pediatric solid organ transplantation recipient: A multidisciplinary approach to diagnosis and management

Diarrhea in the pediatric solid organ transplantation (SOT) recipient is a frequent complaint that is associated with significant morbidity and impaired quality of life. There are limited published data regarding the specific epidemiology, diagnostic evaluation, and treatment of diarrhea after SOT in children. Pediatric SOT recipients have an increased risk of developing diarrhea because of a generalized immunosuppressed state, epidemiologic exposures, and polypharmacy. There is a need to standardize the diagnostic evaluation of diarrhea in children after SOT to facilitate an accurate diagnosis and timely treatment. Herein, we review the available published data and propose a systematic, stepwise approach to the evaluation of diarrhea in this high-risk population, focusing on timely diagnosis of both infectious and non-infectious causes, in order to provide focused management. Prospective studies are needed to better assess the true prevalence, risk factors for, etiologies, and complications of diarrhea in pediatric SOT patients that will guide optimal management. Development of effective vaccines and antiviral therapies for enteric viruses may also contribute to improved outcomes.

Rapid resolution of colitis related to immunosuppressive medication after infliximab administration

Immunosuppression is necessary after solid organ transplantation. The non-infectious side effects associated with many of these agents are not well understood. We report a case of colitis, most resembling inflammatory bowel disease, that persisted despite withdrawal of tacrolimus and mycophenolate mofetil and transition to alternative agents. The patient was treated for clostridium difficile without improvement. Endoscopic biopsies demonstrated non-specific inflammation without evidence of active infection. An extensive immunologic and oncologic workup was negative. Ultimately, we trialed the administration of infliximab, a monoclonal antibody that inhibits TNF-alpha receptors that is commonly used in the treatment of inflammatory bowel disease. With infliximab treatment, the patient experienced rapid resolution of his disease and has remained in remission.

Optimal Delivery of Follow-Up Care After Allogeneic Hematopoietic Stem-Cell Transplant: Improving Patient Outcomes with a Multidisciplinary Approach

The increasing indications for allogeneic stem-cell transplant in patients with hematologic malignancies and non-malignant diseases combined with improved clinical outcomes have contributed to increase the number of long-term survivors. However, survivors are at increased risk of developing a unique set of complications and late effects, besides graft-versus-host disease and disease relapse. In this setting, the management capacity of a single health-care provider can easily be overwhelmed. Thus, to provide appropriate survivorship care, a multidisciplinary approach for the long-term follow-up is essential. This review aims at summarizing the most relevant information that a health-care provider should know to establish a follow-up care plan, in the light of individual exposures and risk factors, that includes all organ systems and considers the psychological burden of these patients.

Comparative Evaluation of Median Versus Youden Index Dichotomization Methods: Exposure-Response Analysis of Mycophenolic Acid and Acyl-Glucuronide Metabolite

BACKGROUND AND OBJECTIVES

Dichotomization of pharmacokinetic exposure measures in exposure-response relationship studies provides results that are interpretable in clinical care. Several methods exist in the literature on how to define the cut-off values needed for the dichotomization process. Commonly, the sample median is utilized to define the dichotomizing value; however, statistical methods based on the exposure metric and its association with the outcome are argued to result in a more proper definition of the optimal cut-point. The Youden index is a recommended statistical method to define the cut-off value. The current analysis objective is to compare the dichotomization results based on the Youden index versus median methods.

METHODS

Utilizing mycophenolic acid (MPA) exposure data and its related acute rejection and leukopenia outcome variables, the current study compared the MPA exposure-response relationship outcomes when MPA exposure is dichotomized via the Youden index versus median methods. Univariate logistic models were utilized to quantify the relationships between MPA exposure, including total MPA, unbound MPA, and the acyl-glucuronide metabolite of MPA, and the probabilities of acute rejection and leukopenia.

RESULTS

The overall trend of the results of the logistic models demonstrated a general similarity in the inferred exposure-response associations when considering either the Youden index-based or the median-based dichotomization methods.

CONCLUSION

The results demonstrated in this analysis suggest that both the Youden index and the median methods provide similar conclusions when dichotomization of a continuous variable is considered. However, confirmation of these conclusions comes from future powered studies that include a larger number of subjects.

Vitamin B12 status in kidney transplant recipients: association with dietary intake, body adiposity and immunosuppression

The aim of the present study was to evaluate the prevalence of vitamin B12 (B12) deficiency in kidney transplant recipients (KTR) and its possible association with B12 dietary intake, body adiposity and immunosuppressive drugs. In this cross-sectional study, we included 225 KTR, aged 47·50 (sd 12·11) years, and 125 (56 %) were men. Serum levels of B12 were determined by chemiluminescent microparticle intrinsic factor assay and the cut-off of 200 pg/ml was used to stratify KTR into B12-sufficient or B12-deficient group. B12 dietary intake was evaluated by three 24 h dietary recalls and was considered adequate when ≥2·4 μg/d. Body adiposity was estimated after taking anthropometric measures and using the dual-energy X-ray absorptiometry (DXA) method. B12 deficiency was seen in 14 % of the individuals. B12-deficient group, compared with the B12-sufficient group, exhibited lower intake of B12 (median 2·42 (interquartile range (IQR) 1·41-3·23) v. 3·16 (IQR 1·94-4·55) μg/d, P = 0·04) and higher values of waist circumference (median 96·0 (IQR 88·0-102·5) v. 90·0 (IQR 82·0-100·0) cm, P = 0·04). When the analysis included only women, B12 deficiency was associated with higher total and central body adiposity measurements obtained with anthropometry (BMI, body adiposity index, waist and neck circumferences) and DXA (total and trunk body fat). Among individuals with adequate intake of B12, the deficiency of this vitamin was more frequently seen in those using mycophenolate mofetil (MMF) (17 %) v. azathioprine (2 %), P = 0·01. In conclusion, the prevalence of B12 deficiency in KTR was estimated as 14 % and was associated with reduced intake of B12 as well as higher adiposity, especially in women, and with the use of MMF.

Immunosuppressive drugs and the gastrointestinal tract in renal transplant patients

Gastrointestinal (GI) discomfort is common after renal transplantation and can be caused by the use of various immunosuppressive drugs. GI symptoms affect the quality of life, lead to an impaired graft survival and an increased mortality. Moreover, diseases and disturbances of the GI tract also affect the pharmacokinetics of immunosuppressive drugs. This review addresses the interaction between immunosuppressive agents and GI disorders. The GI tract is involved in the metabolism of several immunosuppressive drugs. Calcineurin inhibitors, mTor inhibitors, and corticosteroids are subjected to metabolism by the intestinal cytochrome P450 (CYP3A) and by the drug efflux pump ABCB1. Mycophenolate is partly metabolized in the stomach and intestine and undergoes enterohepatic recirculation. Gastrointestinal disturbances can lead to a modified exposure to immunosuppressive drugs. In the first and second part of this review, we focus on the role of the GI tract in the pharmacokinetics of the immunosuppressive drugs and how to adjust immunosuppressive therapy in patients with vomiting, need for tube feeding, delayed gastric emptying, intestinal resection, and diarrhea. In the third part, we review the GI adverse effects of the various immunosuppressive drugs, with special attention for diarrhea and dyspepsia. Finally, we discuss the effects of drugs used for relief of GI complaints on the exposure to immunosuppressive agents.

Celiac-like Enteropathy Associated With Mycophenolate Sodium in Renal Transplant Recipients

Background

Although colonic injury is a well-known complication of mycophenolic acid (MPA), the involvement of the upper gastrointestinal tract is less extensively documented. We present the occurrence of celiac-like duodenopathy manifested as a severe diarrhea syndrome in 2 renal transplant recipients on enteric-coated mycophenolate sodium.

Methods

The patients belong to a setting of 16 renal transplant recipients under MPA suffering from chronic diarrhea in the absence of MPA-related colitis.

Results

Both patients had a history of persistent diarrhea with significant weight loss. Colonic mucosa was unremarkable, whereas duodenal biopsies revealed celiac-like changes with increased epithelial cell apoptosis. Clinical symptoms completely resolved, and follow-up biopsies demonstrated normalization of histology after enteric-coated mycophenolate sodium withdrawal and switching to azathioprine.

Conclusions

Celiac-like enteropathy seems to represent a rare side effect of MPA-associated immunosuppressive therapy and should be taken into account in the differential diagnosis of diarrhea in transplant recipients treated with MPA particularly in the absence of MPA-related colitis. As macroscopic lesions are usually missing, blind duodenal biopsies are necessary to establish the diagnosis.

Development of Duodenal Ulcers due to the Discontinuation of Proton Pump Inhibitors After the Induction of Sofosbuvir Plus Ledipasvir Therapy: A Report of Two Cases

Sofosbuvir plus ledipasvir (SOF-LDV) combination therapy is a promising therapy for post-transplant hepatitis C virus (HCV) reinfection. It is known that gastric pH elevation induces lower absorption of ledipasvir; therefore, the use of proton pump inhibitors (PPIs) should be considered regarding dose reduction after SOF-LDV therapy induction. Here, we report two patients who developed duodenal ulcers due to the discontinuation of PPIs after the induction of SOF-LDV therapy for post-transplant HCV reinfection. The first patient was a 71-year-old man who had undergone living donor liver transplantation due to HCV-related liver cirrhosis. Lansoprazole, 30 mg daily, was discontinued upon SOF-LDV therapy induction. Seven days after SOF-LDV therapy induction, gastrointestinal endoscopy revealed the presence of a duodenal ulcer. The second patient was a 54-year-old man who had undergone living donor liver transplantation due to HCV-related end-stage liver disease. Similar to the first patient, rabeprazole sodium was discontinued upon the induction of SOF-LDV therapy. Eighteen days after SOF-LDV therapy induction, gastrointestinal endoscopy revealed the presence of a duodenal ulcer. In both cases, these duodenal ulcers improved after the resumption of the administration of PPIs, and a sustained virologic response at 12 weeks was achieved by SOF-LDV therapy with PPI use. Thus, PPI use should be continued consistently during SOF-LDV therapy for post-transplant HCV reinfection.

Sites of gastrointestinal lesion induced by mycophenolate mofetil: a comparison with enteric-coated mycophenolate sodium in rats

Background

Immunosuppressant drugs for renal transplant mycophenolate mofetil (MMF) and enteric-coated mycophenolate sodium (EC-MPS) cause gastrointestinal (GI) disorders. The specific site of GI tract targeted by MMF and EC-MPS remains unclear.

Methods

In this study, we investigated the effects of MMF and EC-MPS on stomach, duodenum, jejunum, ileum, colon and rectum using a rat model. Rats were randomized into five groups: control, MMF (100 mg/kg·d), mofetil (30 mg/kg·d), EC-MPS (72 mg/Kg·d), mofetil + EC-MPS. Each group was treated with drugs once a day for 7 days through intra-gastric gavage. Diarrhea grade of each rat were measured every day, as well as the body weight. Blood was collected by tail nick and Seven days later, the rats were sacrificed, GI tissues were collected for Histological research.

Results

The results showed that diarrhea grade and weight loss were significantly higher in MMF group than other groups. The pathological score of MMF group was significantly higher than EC-MPS group and EC-MPS + mofetil group in jejunum and ileum tissues, but not other segments of GI tract. Absorption of EC-MPS is delayed, compared to that of MMF. MPAG concentration in duodenum, jejunum and ileum tissues of MMF group is higher than EC-MPS group. Mofetil may increase the magnitude of MPA absorption.

Conclusions

Our data suggested that MMF might target jejunum and ileum and induce GI injury. EC-MPS causes less injury in GI tract than MMF, probably due to its kinetic property.

Intractable ascites associated with mycophenolate in a simultaneous kidney-pancreas transplant patient: a case report

Background

Mycophenolic acid (MPA), either given as an ester pro-drug or as an enteric-coated sodium salt, is the most commonly prescribed anti-proliferative immunosuppressive agent used following organ transplantation and widely applied in immune-mediated diseases. Clinicians are well aware of common adverse reactions related to MPA treatment, in particular diarrhea, leukopenia and infections. Here we report a case of severe, persistent ascites associated with MPA treatment. The otherwise unexplained and intractable ascites, requiring repeated paracenteses for more than 8 months, rapidly ceased with stopping the MPA treatment. To our knowledge this is the first case of severe ascites associated with MPA treatment reported in the scientific literature.

Case Presentation

A 45-year old female with type 1 diabetes mellitus received a simultaneous kidney-pancreas transplant. The surgery was uneventful. However, post-operatively she developed severe transudative ascites requiring in total more than 40 paracenteses treatments draining in the average 2.8 l of ascites fluid. The ascites formation persisted despite exclusion of a surgical complication, fully functioning kidney and pancreas allografts, lack of any significant proteinuria, normalization of circulating albumin levels, intensive use of diuretics and deliberate attempts to increase the intervals between the paracentesis treatments. Various differential diagnoses, including infectious, hepatic, vascular and cardiac causes were ruled out. Nine months after surgery enteric-coated mycophenolate sodium was switched to azathioprine after which ascites completely resolved. When mycophenolate was recommenced abdominal fullness and weight gain reoccurred. The patient had to be switched to long-term azathioprine treatment. More than 1 year post-conversion the patient remains free of ascites.

Conclusion

MPA is the most widely used antimetabolite immunosuppressive agent. We suggest to consider MPA treatment in the differential diagnosis of severe and unexplained ascites in transplant and non-transplant patients.

Deep Ulcers in the Ileum Associated with Mycophenolate Mofetil

A 54-year-old man was treated with mycophenolate mofetil (MMF) after undergoing living donor renal transplantation. Two years later, he experienced repeated episodes of diarrhea, and his C-reactive protein (CRP) level was found to be 12.63 mg/dL. Ileocolonoscopy showed multiple deep, punched-out ulcers that were similar to Behçet's disease (BD) and cytomegalovirus (CMV) in the ileum. CMV infection was suspected. However, anti-cytomegalovirus agents were ineffective. The patient was subsequently diagnosed with gastrointestinal toxicity of MMF and MMF was switched to mizoribine. His symptoms improved immediately, and his CRP level normalized. Six months later, the patient's mucosa was healed.

Giardia lamblia infection after pancreas-kidney transplantation

Infection is a common complication of solid organ transplantation. It is associated with an increased risk of acute cellular rejection and loss of graft function. The most common infections are due to bacteria and viruses, including transmission of cytomegalovirus from donor to recipient. In the past years, an increasing number of parasitic infections have been documented in transplant recipients. We describe the first reported case of intestinal Giardia lamblia transmission following simultaneous pancreas and kidney transplantation.

Unusually late-onset mycophenolate mofetil-related colitis

PURPOSE

Serious gastrointestinal complications arising 13 years after the initiation of posttransplant immunosuppressant therapy with mycophenolate mofetil are reported.

SUMMARY

Over a three-month period, a male heart transplant recipient who had taken oral mycophenolate mofetil (2 g daily) for 13 years as part of an immunosuppressant maintenance regimen developed diarrhea and weight loss leading to renal failure and metabolic acidosis. There was no evidence of opportunistic infection, and immunostaining for cytomegalovirus yielded negative results. Colonoscopy revealed areas of congested, erythematous, and nodular mucosa. Histological examination of mucosal biopsy specimens revealed pathological abnormalities typical of those seen in cases of mycophenolate mofetil-associated colitis. On discontinuation of mycophenolate mofetil use, the patient's diarrhea resolved and his renal function improved. Colitis, diarrhea, and other gastrointestinal complications are commonly reported in patients receiving mycophenolate mofetil, an immunosuppressant widely used to prevent rejection of solid organ or bone marrow transplants; however, the onset of such symptoms after more than a decade of continuous use of the drug has not been previously reported. This case suggests that mycophenolate mofetil toxicity should be considered in the evaluation of late-onset posttransplant diarrhea regardless of the duration of therapy.

CONCLUSION

A 33-year-old man maintained on mycophenolate mofetil for 13 years after heart transplantation developed diarrhea, weight loss, and acute kidney injury over a three-month period. Colonoscopy and biopsy revealed pathological changes consistent with mycophenolate mofetil toxicity, and the patient's symptoms resolved after the drug was discontinued.

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.

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.

Acute colonic pseudo-obstruction caused by mycophenolate mofetil in a kidney transplant recipient

Mycophenolate mofetil is a component of immunosuppressive regimens in solid-organ transplant recipients. Gastrointestinal symptoms such as nausea, abdominal pain, and diarrhea without fever are common in patients treated with mycophenolate mofetil. We treated a patient who had acute colonic pseudo-obstruction after kidney transplant that resolved after discontinuing mycophenolate mofetil. The disorder recurred soon after resuming mycophenolate mofetil, which is evidence for an association between mycophenolate mofetil and acute colonic pseudo-obstruction in this patient.

Mycophenolate mofetil-induced segmental colitis mimicking ischemic colitis

Mycophenolate mofetil (MMF) is a commonly used drug in the prevention of allograft rejection in patients with solid organ transplants. Although diffuse colitis has been described in MMF-related colitis, segmental colitis has not been reported. We report the case of a 64-year-old male on MMF therapy who presented for evaluation of afebrile diarrhea and abdominal pain. Flexible sigmoidoscopy revealed a segmental erythematous mucosa with ulceration in the sigmoid colon, descending colon, splenic flexure and proximal transverse colon. Biopsies of these areas showed dilated damaged crypts, eosinophilic epithelial changes and crypt abscesses with apoptotic bodies consistent with MMF-induced injury. MMF was discontinued, leading to a significant improvement of his symptoms.

Drug-induced injury in the gastrointestinal tract

Abnormalities of the gastrointestinal tract due to drug-induced injuries are common and often have important clinical consequences. Medications may cause damage by direct corrosive effects on mucosae or by alter processes, mucosal immunity, and local environmental conditions. The aim of this review is to guide practicing pathologists in the identification of drug-related injuries in gastrointestinal mucosal biopsies and resection specimens. Common causes of injury and their gross, endoscopic, and microscopic features are presented.

Mycophenolic acid mediated disruption of the intestinal epithelial tight junctions

Gastrointestinal toxicity is a common adverse effect of mycophenolic acid (MPA) treatment in organ transplant patients, through poorly understood mechanisms. Phosphorylation of myosin light chain 2 (MLC2) is associated with epithelial tight junction (TJ) modulation which leads to defective epithelial barrier function, and has been implicated in GI diseases. The aim of this study was to investigate whether MPA could induce epithelial barrier permeability via MLC2 regulation. Caco-2 monolayers were exposed to therapeutic concentrations of MPA, and MLC2 and myosin light chain kinase (MLCK) expression were analyzed using PCR and immunoblotting. Epithelial cell permeability was assessed by measuring transepithelial resistance (TER) and the flux of paracellular permeability marker FITC-dextran across the epithelial monolayers. MPA increased the expression of MLC2 and MLCK at both the transcriptional and translational levels. In addition, the amount of phosphorylated MLC2 was increased after MPA treatment. Confocal immunofluorescence analysis showed redistribution of TJ proteins (ZO-1 and occludin) after MPA treatment. This MPA mediated TJ disruption was not due to apoptosis or cell death. Additionally ML-7, a specific inhibitor of MLCK was able to reverse both the MPA mediated decrease in TER and the increase in FITC-dextran influx, suggesting a modulating role of MPA on epithelial barrier permeability via MLCK activity. These results suggest that MPA induced alterations in MLC2 phosphorylation and may have a role in the patho-physiology of intestinal epithelial barrier disruption and may be responsible for the adverse effects (GI toxicity) of MPA on the intestine.

A case series of de novo inflammatory bowel disease after kidney transplantation

Diarrhea, which is common after transplantation, may be due to infections and immunosuppressive therapy. Inflammatory bowel disease (IBD) de novo or as an exacerbation of pre-existent disease is a rare complication after kidney transplantation with pre-existing disease having a less aggressive clinical course than the de novo disease. Cytomegalovirus mismatch, prescription of tacrolimus instead of cyclosporine or mycophenolate mofetil rather than azathioprine as well as low-dose corticosteroid treatments have been linked to an increased incidence of IBD. This series of renal transplant recipients with de novo IBD showed a higher incidence and more aggressive course than that previously described, possibly related to increased use of tacrolimus with minimization of steroids.

Diarrhea in solid-organ transplant recipients: a review of the evidence

OBJECTIVE

To provide a comprehensive review of the literature as it relates to diarrhea in solid organ transplant (SOT) recipients. In this article, we review the epidemiology, pathogenesis, clinical manifestations, diagnosis and management of diarrhea in SOT recipients and discuss recent advances and challenges.

METHODS

Two investigators conducted independent literature searches using PubMed, Web of Science, and Scopus until January 1st, 2013. All databases were searched using a combination of the terms diarrhea, solid organ transplant, SOT, transplant associated diarrhea, and transplant recipients. Articles that discussed diarrhea in SOT recipients were reviewed and relevant cross-references also read and evaluated for inclusion. Selection bias could be a possible limitation of the approach used in selecting or finding articles for this article.

FINDINGS

Post-transplant diarrhea is a common and distressing occurrence in patients, which can have significant deleterious effects on the clinical course and well-being of the organ recipient. A majority of cases are due to infectious and drug-related etiologies. However, various other etiologies including inflammatory bowel disease must be considered in the differential diagnosis. A step-wise, informed approach to post-transplant diarrhea will help the clinician achieve the best diagnostic yield. The use of diagnostic endoscopy should be preceded by exclusion of an infectious or drug-related cause of diarrhea. Empiric management with antidiarrheal agents, probiotics, and lactose-free diets may have a role in managing patients for whom no cause can be determined even after an extensive investigation.

CONCLUSIONS

Physicians should be familiar with the common etiologies that result in post-transplant diarrhea. A directed approach to diagnosis and treatment will not only help to resolve the diarrhea but also prevent potentially life-threatening consequences including loss of the graft as well. Prospective studies are required to determine the etiology of post-transplant diarrhea in different clinical and geographic settings.

Histological spectrum of mycophenolate mofetil-related colitis: association with apoptosis

AIMS

The main purpose of this study was to define diagnostic histological characteristics of mycophenolate mofetil (MMF)-related colitis in association with crypt epithelial cell turnover.

METHODS AND RESULTS

The examined material included 43 colonic biopsies from renal transplant recipients with MMF administration and persistent diarrhoea. Thirty-three cases showed MMF-related colitis, while 10 showed no significant changes. The histological findings were scored and correlated with the apoptotic index (AI) and with the proliferation rate (PR) of the crypt epithelium examined by TUNEL assay and Ki-67 immunoexpression. Ten cases of Crohn disease and 10 of ulcerative colitis were used as comparative groups. Crypt distortion and loss as well as increased apoptosis constituted the main features, their degree and combination leading either to an inflammatory bowel disease (IBD)-like (82%) or to a graft-versus-host disease-like pattern (18%). A high AI was associated more frequently with moderate and severe crypt distortion, while the values were significantly higher compared with the control groups (P < 0.01). High PR was noted in 18 of 29 (62.1%) of the cases.

CONCLUSIONS

The diagnostic hallmark of MMF-related colitis is an IBD-like histological pattern in association with increased epithelial apoptosis, while apoptotic cell death seems to be a potential pathogenetic factor of mucosa injury.

Drug-induced inflammatory bowel disease and IBD-like conditions

The pathogenesis of inflammatory bowel disease (IBD) is multifactorial and results from an interaction between genetic, immunologic, microbial, and environmental factors. Certain drugs could act as a trigger for the disease and have been implicated in the development of new onset IBD in a number a studies. These relationships are based on case reports and cohort studies, as proving this in the context of randomized controlled trials would be difficult. Drugs that have been linked to causing or worsening IBD include isotretinoin, antibiotics, nonsteroidal antiinflammatory drugs, oral contraceptives, mycophenolate mofetil, etanercept, ipilimumab, and rituximab. Bowel preparation for colonoscopy has also been associated with aphthoid lesions that may be confused with IBD. However, given the source of these reports we have to be cautious in the interpretation of the data before concluding that these drugs trigger IBD and what is being observed is not related to other confounding factors. Different pathogenic mechanisms have been suggested for the different drugs listed above. In order to clarify the confusion a comprehensive literature review was performed with the goal of advancing the knowledge on this subject.

Mycophenolic acid-related diarrhea is not associated with polymorphisms in SLCO1B nor with ABCB1 in renal transplant recipients

OBJECTIVE

We investigated the association between genetic polymorphisms in ABCB1 and SLCO1B and mycophenolic acid (MPA) pharmacokinetics, and MPA-related diarrhea and leukopenia in 338 kidney transplant recipients.

METHODS

A total of 338 patients participating in an international, randomized-controlled clinical trial were genotyped for ABCB1 and SLCO1B. Patients were all treated with mycophenolate mofetil and either cyclosporine or tacrolimus. MPA-area under the curve (AUCs), MPA-glucuronide AUCs and acylglucuronide-AUCs were measured on days 3 and 10, and months 1, 3, 6, and 12 after kidney transplantation.

RESULTS

The risk of developing diarrhea was 1.8-fold higher in patients cotreated with tacrolimus compared with patients cotreated with cyclosporine (95% confidence interval: 1.03-3.13; P=0.038). ABCB1 and SLCO1B SNPs were not associated with dose-adjusted exposure to MPA, MPA-glucuronide, nor acylglucuronide-MPA nor with the incidence of diarrhea or leukopenia.

CONCLUSION

Genotyping for ABCB1 or SLCO1B pretransplantation is unlikely to be of clinical value for individualization of MPA therapy.

Mycophenolate Mofetil-Related Enterocolitis and Weight Loss: A Pediatric Case Series

Mycophenolate mofetil (MMF) is an immunosuppressive medication utilized in the management of both autoimmune and solid organ transplant patients. Diarrhea is a common gastrointestinal side effect of MMF, but more severe forms of GI symptoms are described in renal transplant patients with a distinct pattern of histopathologic change, similar to graft-versus-host disease or Crohn's disease. This rare entity, commonly referred to as “MMF-related enterocolitis,” has been described in adult patients, mostly in renal transplant patients, and in only two pediatric renal transplant patients. In previously reported cases, symptoms and abnormal histopathology improve with dose reduction of MMF. We describe a series of three pediatric patients with varied underlying disease process who presented with severe diarrhea and histopathologic findings characteristic of MMF-related enterocolitis, who share a novel finding of weight loss as a complication of MMF-related enterocolitis in pediatric patients.

ATP-binding cassette transporters as pharmacogenetic biomarkers for kidney transplantation

Immunosuppressive drugs used in organ transplantation are highly effective in preventing acute rejection. However, the clinical use of these drugs is complicated by the fact that they display highly variable pharmacokinetics and pharmacodynamics between individual patients. The influence of genetic variation on the interindividual variability in immunosuppressive drug disposition, efficacy, and toxicity has been explored in recent years. The polymorphically-expressed ATP-binding cassette (ABC) transporter proteins, in particular ABCB1 and ABCC2, have been investigated extensively because they play an important role in the absorption, distribution and elimination of many immunosuppressive drugs in use today. From these studies it can be concluded that polymorphisms in ABCB1 and ABCC2 have no consistent effect on immunosuppressant pharmacokinetics and toxicity although polymorphisms in ABCB1 appear to be related to the risk of developing calcineurin inhibitor-related nephrotoxicity. However, the latter needs to be replicated before an individual's ABCB1 genotype can become a useful marker that is applied in clinical practice. Future studies evaluating the influence of ABC transporter gene polymorphisms should explore the relationship with intracellular rather than systemic drug concentrations further in well-designed clinical studies. Until then, single-nucleotide polymorphisms in ABC transporter genes are not suitable to act as biomarkers for solid organ transplantation.

The influence of pharmacogenetics and cofactors on clinical outcomes in kidney transplantation

INTRODUCTION

Immunosuppressive drugs have a narrow therapeutic range and large inter-individual response variability. This has prompted pharmacogenetic studies, mostly with regard to their dose-concentration relationships, but also about proteins involved in their pharmacodynamics. Some polymorphisms of genes involved in their disposition pathways were shown to affect their dose-concentration relationships. The impact of pharmacogenetics on tissue distribution and the resulting clinical effects have less often been studied. More importantly, a few single nucleotide polymorphisms seem to have a significant impact on the incidence of acute rejection or the adverse effects of immunosuppressants. Environmental factors often interact with such genotype-phenotype relationships.

AREAS COVERED

This article reviews the impact of genetic polymorphisms of the metabolic enzymes, membrane transporters and target proteins of mycophenolic acid, calcineurin inhibitors and mammalian target of rapamycin inhibitors on clinical outcomes in kidney transplantation.

EXPERT OPINION

The current level of evidence is not yet high enough to recommend pharmacogenetic personalization of immunosuppressive regimens in transplant recipients. The prevention of cellular toxicity associated with local metabolism or transport, which cannot be addressed by routine monitoring, is worth investigating further.

Patterns of injury in mycophenolate mofetil-related colitis

Mycophenolate mofetil (MMF) was introduced as a new immune-suppression drug in the mid-1990s. It is widely utilized in solid-organ transplantation immune-suppression regimens. Side effects include gastrointestinal (GI) toxicity in the form of nausea, vomiting, and diarrhea. Physicians tend to reduce the dose of MMF or switch their patients to an enterio-coated formula to overcome the side effects. Because GI side effects are well linked to MMF, colonoscopy is not utilized in most of the cases to investigate the diarrhea. However, Crohn's disease-like changes in the colon, erosive enterocolitis, and graft versus host disease-like colonic changes associated with the use of MMF have been reported. Colonic findings in five patients whose symptoms resolved after substituting another agent for MMF are described in the present report. Repeat colonoscopy 4 months following discontinuation of MMF showed reparative changes in one of our patients. MMF is an important drug in organ transplantation immune-suppression regimens; however, with its widespread usage, additional side effects continue to be recognized.

Pharmacogenetic impact of UDP-glucuronosyltransferase metabolic pathway and multidrug resistance-associated protein 2 transport pathway on mycophenolic acid in thoracic transplant recipients: an exploratory study

STUDY OBJECTIVE

To assess the contribution of polymorphisms in the uridine diphosphate glucuronosyltransferase gene (UGT) and the multidrug resistance-associated protein 2 gene (ABCC2) to mycophenolic acid (MPA) pharmacokinetics and clinical outcomes in thoracic transplant recipients.

DESIGN

Open-label, cross-sectional study.

SETTING

Transplant clinic in Vancouver, British Columbia, Canada.

PATIENTS

Sixty-eight thoracic (36 lung, 32 heart) transplant recipients who were receiving steady-state oral mycophenolate mofetil.

MEASUREMENTS AND MAIN RESULTS

Eleven blood samples were obtained from each patient over a 12-hour dosing period. Plasma concentrations of MPA (active metabolite of mycophenolate mofetil), the MPA metabolites 7-Omycophenolic acid glucuronide (MPAG) and acyl glucuronide (AcMPAG), and free MPA were measured, and dose-normalized conventional pharmacokinetic parameters were determined by noncompartmental methods. Genetic polymorphisms in UGT and ABCC2 were determined by sequencing, and their contributions to pharmacokinetic variability were investigated by using multivariate analysis. For both the lung and heart transplant groups, the UGT2B7 variant 802T (Tyr(268) or UGT2B7*2, rs7439366) and the UGT2B7 variant -138A modified AcMPAG exposure (2.5-3.7-fold and 9.3-12.3-fold higher AcMPAG area under the concentration-time curve [AUC] and AcMPAG:MPA ratio, respectively). In an exploratory analysis, occurrences of rejection, infection, anemia, and leukopenia were associated with an AcMPAG AUC greater than 50 μg·hour/ml and an AcMPAG:MPA ratio greater than 2.

CONCLUSION

UGT2B7 is a promising gene candidate that may influence MPA pharmacokinetics clinically; however, larger clinical pharmacogenetic studies in thoracic transplant subpopulations are warranted to corroborate the role of AcMPAG and UGT2B7 variants in optimizing mycophenolate mofetil therapy.

Duodenal villous atrophy: a cause of chronic diarrhea after solid-organ transplantation

Persistent diarrhea is commonly observed after solid organ transplantation (SOT). A few cases of mycophenolate mofetil (MMF)-induced duodenal villous atrophy (DVA) have been previously reported in kidney-transplant patients with chronic diarrhea. Herein, we report on the incidence and characteristics of DVA in SOT patients with chronic diarrhea. One hundred thirty-two SOT patients with chronic diarrhea underwent an oesophago-gastroduodenoscopy (OGD) and a duodenal biopsy after classical causes of diarrhea have been ruled out. DVA was diagnosed in 21 patients (15.9%). It was attributed to mycophenolic acid (MPA) therapy in 18 patients (85.7%) (MMF [n = 14] and enteric-coated mycophenolate sodium [n = 4]). MPA withdrawal or dose reduction resulted in diarrhea cessation. The incidence of DVA was significantly higher in patients with chronic diarrhea receiving MPA compared to those who did not (24.6% vs. 5.1%, p = 0.003). DVA was attributed to a Giardia lamblia parasitic infection in two patients (9.5%) and the remaining case was attributed to azathioprine. In these three patients, diarrhea ceased after metronidazole therapy or azathioprine dose reduction. In conclusion, DVA is a frequent cause of chronic diarrhea in SOT recipients. MPA therapy is the most frequent cause of DVA. An OGD should be proposed to all transplant recipients who present with persistent diarrhea.

[Intraabdominal infection in inmunodepressed patients]

Diseases of the gastrointestinal system frequently complicate immunosuppressed patients. Endogenous flora is the principal source of infection in humans, especially in patients with dysfunction of the digestive epithelial barrier due to various factors. Bacterial translocation, traumatisms, ischemia and surgery are frequent events in the general population. In addition, important risk factors for abdominal infections in specific patients include tumoral infiltration, mucositis complicating chemotherapy and/or radiotherapy, hypoproteinemia, neutropenia and lymphocyte deficiency. Clinical pictures vary according to patients' baseline condition and the environmental setting, including nosocomial infections. The differential clinical characteristics of abdominal infections observed in distinct types of immunosuppressed patients are reviewed.