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

Lower Weight-Based Mycophenolate Mofetil Dosing is Associated with Superior Outcomes after Haploidentical Hematopoietic Cell Transplant with Post-transplant Cyclophosphamide

Mycophenolate mofetil (MMF) is commonly included in post-transplant cyclophosphamide (PTCy) based graft-versus-host disease (GVHD) prophylaxis after haploidentical (haplo) hematopoietic cell transplant (HCT). In the non-PTCy setting, higher MMF dose/kg has been shown to reduce rates of acute graft-versus-host disease (GVHD). When used in conjunction with PTCy, MMF is dosed at 15 mg/kg three times daily up to a maximum dose of 3 g/day. Thus, patients who weigh ≥67 kg receive 3 g/day and a variable dose/kg of MMF. We investigated the impact of MMF dose/kg on clinical outcomes following haploidentical PBSCT with PTCy-based GVHD prophylaxis. All consecutive adult patients with hematologic malignancies receiving haploidentical T cell replete peripheral blood stem cell transplant (PBSCT) with PTCy/MMF and either tacrolimus or sirolimus at the Moffitt Cancer Center or City of Hope between April 2014-August 2020 were included. For analyses, MMF dose relative to patient actual body weight (mg/kg/day), was stratified into categories of low (<29 mg/kg/day), low intermediate (29-34 mg/kg/day), high intermediate (35-41 mg/kg/day), and high (>41 mg/kg/day). Three hundred eighty-six patients were included. Of these, 54 patients received low dose, 73 low intermediate, 137 high intermediate and 122 high dose MMF by relative weight exposure. In multivariate analysis, low MMF dose exposure was associated with reduced rates of relapse in comparison to the high dose group (HR = 0.45, 95% CI: 0.21 to 0.94, P = .03). This led to superior PFS among patients with low compared to high MMF dose exposure (HR = 0.58, 95% CI: 0.34 to 0.99, P = .045). MMF relative dose exposure was not associated with engraftment, GVHD, nonrelapse mortality, or OS. In this study of patients receiving haploidentical PBSCT with PTCy based GVHD prophylaxis, low MMF dose/kg was associated with improved rates of relapse and PFS. Future prospective studies should investigate optimal dosing strategies of MMF when given with the PTCy regimen.

Microbial bile acid metabolite ameliorates mycophenolate mofetil-induced gastrointestinal toxicity through vitamin D3 receptor

Mycophenolate mofetil (MMF) is one of the most used immunosuppressive drugs in organ transplantation, but frequent gastrointestinal (GI) side effects through unknown mechanisms limit its clinical use. Gut microbiota and its metabolites were recently reported to play a vital role in MMF-induced GI toxicity, but the specific mechanism of how they interact with the human body is still unclear. Here, we found that secondary bile acids (BAs), as bacterial metabolites, were significantly reduced by MMF administration in the gut of mice. Microbiome data and fecal microbiota transfer model supported a microbiota-dependent effect on the reduction of secondary BAs. Supplementation of the secondary BA lithocholic acid alleviated MMF-induced weight loss, colonic inflammation, and oxidative phosphorylation damage. Genetic deletion of the vitamin D3 receptor (VDR), which serves as a primary colonic BA receptor, in colonic epithelial cells (VDRΔIEC) abolished the therapeutic effect of lithocholic acid on MMF-induced GI toxicity. Impressively, we discovered that paricalcitol, a Food and Drug Administration-approved VDR agonist that has been used in clinics for years, could effectively alleviate MMF-induced GI toxicity. Our study reveals a previously unrecognized mechanism of gut microbiota, BAs, and VDR signaling in MMF-induced GI side effects, offering potential therapeutic strategies for clinics.

Exploring Acute Pancreatitis in Kidney Transplant Recipients: A Multicentre Retrospective Cohort Analysis of Incidence, Causes, and Clinical Outcomes

Background: The aim of this multicentre retrospective study is to determine the incidence, etiology, clinical characteristics, and outcomes of kidney transplant recipients diagnosed and treated for acute pancreatitis. Methods: We analyzed data from kidney transplant recipients who received kidney allografts between October 1973 and December 2023 and were diagnosed and treated for acute pancreatitis. Results: Of 2482 patients who received kidney allografts, 10 (0.4%) (5 male) were diagnosed with acute pancreatitis, with a mean age of 48.6 years. Patients were diagnosed with acute pancreatitis between 3 weeks and 24 years after the transplantation. Possible etiologies included cholecystolithiasis, COVID-19, hypercalcemia, postprocedural, use of cannabis, trimetoprim-sulphometoxasole, statins, sirolimus, tacrolimus and obesity. There was no suspected etiology in two patients. Patients were treated with aggressive hydration, pain alleviation and antibiotics if indicated. Four patients developed complications. Local complications included peripancreatic collections, pseudocyst, and abscesses formation, while systemic complications occurred in the form of Cytomegalovirus (CMV) reactivation and urinary tract infection. All patients survived with preserved kidney allograft function. Conclusions: Acute pancreatitis in kidney transplant recipients is rare. However, it may be linked to significant morbidity and mortality. While symptoms may be nonspecific and brought on by a variety of viral and non-infectious illnesses, as well as adverse effects from immunosuppressive medications, a high degree of awareness is required.

Probiotics treatment ameliorated mycophenolic acid-induced colitis by enhancing intestinal barrier function and improving intestinal microbiota dysbiosis in mice

Background

Mycophenolic acid (MPA)-induced colitis was still a severe side effect and challenge faced by solid transplant recipients. We aimed to explore the function and mechanism of probiotics in the treatment of MPA-induced colitis.

Methods

In this study, 15 mice (C57BL/6) were randomly assigned into three groups: control (CNTL) group (n = 5), MPA group (n = 5) and the MPA + Probiotic group (n = 5). Bifid Triple Viable capsules, which were drugs for clinical use and consisted of Bifidobacterium longum, Lactobacillus acidophilus, and Enterococcus faecalis, were used in Probiotic group. Body weight change, stool scores, colon histopathology and morphology were used to evaluate the disease severity. The intestinal mucosal barrier function was assessed by measuring the expression level of secretory immunoglobulin A (sIgA), Zonula occludens-1 (ZO-1) and Occludin. Finally, 16S rDNA sequencing and bioinformatics analysis were performed on mice feces to compare the different intestinal microbial composition and diversity among three groups.

Results

Compared with the CNTL group, the mice in MPA group showed a significantly decreased body weight, increased stool scores, shortened colon length and severe colon inflammation. However, probiotics treated MPA mice reversed the disease severity, indicating that probiotics ameliorated MPA-induced colitis in mice. Mechanistically, probiotics improved the intestinal barrier function by up-regulating the expression of sIgA, ZO-1 and Occludin. Moreover, MPA-induced colitis led to intestinal microbiota dysbiosis, including the change of Firmicutes/Bacteroidetes ratio, α- and β-diversity. But probiotic treated group showed mild change in these microbial features. Additionally, we found that Clostridiales was the most significantly different microbiota flora in MPA group.

Conclusion

Probiotics treatment ameliorated MPA-induced colitis by enhancing intestinal barrier function and improving intestinal microbiota dysbiosis. Clostridiales might be the dominant functional intestinal microflora and serve as the potential therapy target in MPA-induced colitis.

Altered Bioavailability and Pharmacokinetics in Crohn's Disease: Capturing Systems Parameters for PBPK to Assist with Predicting the Fate of Orally Administered Drugs

Backgrond and Objective

Crohn’s disease (CD) is a chronic inflammatory bowel disease that affects a wide age range. Hence, CD patients receive a variety of drugs over their life beyond those used for CD itself. The changes to the integrity of the intestine and its drug metabolising enzymes and transporters (DMETs) can alter the oral bioavailability of drugs. However, there are other changes in systems parameters determining the fate of drugs in CD, and understanding these is essential for dose adjustment in patients with CD.

Methods

The current analysis gathered all the available clinical data on the kinetics of drugs in CD (by March 2021), focusing on orally administered small molecule drugs. A meta-analysis of the systems parameters affecting oral drug pharmacokinetics was conducted. The systems information gathered on intestine, liver and blood proteins and other physiological parameters was incorporated into a physiologically based pharmacokinetic (PBPK) platform to create a virtual population of CD patients, with a view for guiding dose adjustment in the absence of clinical data in CD.

Results

There were no uniform trends in the reported changes in reported oral bioavailability. The nature of the drug as well as the formulation affected the direction and magnitude of variation in kinetics in CD patients relative to healthy volunteers. Even for the same drug, the reported changes in exposure varied, possibly due to a lack of distinction between the activity states of CD. The highest alteration was seen with S-verapamil and midazolam, 8.7- and 5.3-fold greater exposure, respectively, in active CD patients relative to healthy volunteers. Only one report was available on liver DMETs in CD, and indicated reduced CYP3A4 activity. In a number of reports, mRNA expression of DMETs in the ileum and colon of CD patients was measured, focussing on P-glycoprotein (p-gp) transporter and CYP3A4 enzyme, and showed contradictory results. No data were available on protein expression in duodenum and jejunum despite their dominant role in oral drug absorption.

Conclusion

There are currently inadequate dedicated clinical or quantitative proteomic studies in CD to enable predictive PBPK models with high confidence and adequate verification. The PBPK models for CD with the available systems parameters were able to capture the major physiological influencers and the gaps to be filled by future research. Quantification of DMETs in the intestine and the liver in CD is warranted, alongside well-defined clinical drug disposition studies with a number of index drugs as biomarkers of changes in DMETs in these patients, to avoid large-scale dedicated studies for every drug to determine the effects of disease on the drug’s metabolism and disposition and the consequential safety and therapeutic concerns.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-022-01169-4.

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.

Review article: drug-induced small bowel injury

BACKGROUND

Drug-induced gastrointestinal injury has been increasingly reported, but its exact incidence is not known. The small and large intestines represent the most affected sites of injury, accounting for 20%-40% of all gastrointestinal side effects.

AIM

To provide an updated literature review detailing medications linked to the development of small bowel injury.

METHODS

We conducted a literature search on PubMed from its inception to May 1, 2021. We included English-language original studies, meta-analyses, systematic reviews, review articles and case reports.

RESULTS

Drug-induced enteropathy can range from asymptomatic histological changes resulting in a subtle, self-limited disease to a chronic inflammatory condition mimicking inflammatory bowel disease, or bowel perforation. Endoscopy can demonstrate erythema, mucosal friability, oedema, erosions, ulcers or strictures in severe cases. Histology may include mucosal erosions and ulcerations, focal active enteritis, villous atrophy, epithelial apoptosis or necrotising enteritis. A well-established association has been found with the use of nonsteroidal anti-inflammatory drugs, immunosuppressants, chemotherapeutic agents, antibiotics, immunotherapies, etanercept and olmesartan. Possible associations have been reported with other biologic agents, medications used for glycemic control, antihypertensives, cholinesterase inhibitors, potassium and iron supplements, with conflicting data regarding contraceptives/hormonal therapy and isotretinoin.

CONCLUSION

Physicians should be aware of the manifestations of drug-induced enteropathy as early recognition can lead to prompt discontinuation of the offending therapy and, therefore, a reduced risk of future complications.

Alteration of the gut microbiome in mycophenolate-induced enteropathy: impacts on the profile of short-chain fatty acids in a mouse model

BACKGROUND

Mycophenolic acid (MPA) is the most widely used immunosuppressive drug in transplantation and for autoimmune diseases. Unfortunately, more than 30% of patients experience a typical gastrointestinal adverse effect also referred to as mycophenolate-induced enteropathy. Due to its antibacterial, antifungal, and antiviral properties, MPA exposure is associated with intestinal dysbiosis characterized by a decrease in density and diversity of the microbiome regarding the main bacterial phyla (Firmicutes and Bacteroidetes). These bacterial phyla are known for their metabolic role in maintaining the homeostasis of the digestive tract, particularly through the production of short-chain fatty acids (SCFA) that could contribute to the pathophysiology of mycophenolate-induced enteropathy. Our study aimed at deciphering short-chain fatty acids (SCFA) profile alterations associated with gastrointestinal toxicity of MPA at the digestive and systemic levels in a mouse model.

METHODS

Ten-week old C57BL/6 (SOPF) mice were randomly assigned in 2 groups of 9 subjects: control, and mycophenolate mofetil (MMF, 900 mg/kg/day). All mice were daily treated by oral gavage for 7 days. Individual faecal pellets were collected at days 0, 4 and 8 as well as plasma at day 8 for SCFA profiling. Additionally, after the sacrifice on day 8, the caecum was weighted, and colon length was measured. The proximal colon was cut for histological analysis.

RESULTS

MMF treatment induced around 10% weight loss at the end of the protocol associated with a significant decrease in caecum weight and a slight reduction in colon length. Histological analysis showed significant architectural changes in colon epithelium. Moreover, we observed an overall decrease in SCFA concentrations in faecal samples, especially regarding acetate (at day 8, control 1040.6 ± 278.161 μM versus MMF 384.7 ± 80.5 μM, p < 0.01) and propionate (at day 8, control 185.94 ± 51.96 μM versus MMF 44.07 ± 14.66 μM, p < 0.001), and in plasma samples for butyrate (at day 8, control 0.91 ± 0.1 μM versus MMF 0.46 ± 0.1 μM, p < 0.01).

CONCLUSIONS

These results are consistent with functional impairment of the gut microbiome linked with digestive or systemic defects during MMF treatment.

Post-transplant colitis after kidney transplantation: clinical, endoscopic and histological features

Chronic immunosuppression may increase the risk of post-transplant infection and medication-related injury and may also be responsible for the increased risk of gastrointestinal complications in kidney transplant recipients. Differentiating the various forms of post-transplant colitis is challenging, since most have similar clinical and histological features. This study evaluated the incidence of post-transplant gastrointestinal complications during screening colonoscopy. Kidney transplant recipients undergoing a colonoscopy for any reasons in the period 2014-2018 were included. Among the 134 patients completing the colonoscopy, 74 patients (56%) had an abnormal finding: an adenoma was found in 25 patients (18.6%), while 19 patients (14.1%) had colitis. Mycophenolic acid/related colitis was the most common colitis (6%), while 7 patients (5.2%) developed a de novo inflammatory bowel disease. Patients with post-transplant colitis were younger and with shorter time from transplant compared to patients without colitis. In conclusions, immunosuppression may predispose kidney transplant recipients to an increased risk of post-transplant colitis. Diagnostic colonoscopy should be encouraged in all transplant patients with refractory diarrhea and gastrointestinal symptoms to allow a prompt diagnosis and a timely treatment, finally improving the quality of life and long-term outcomes of affected patients.

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.

Gastrointestinal complications after kidney transplantation

Gastrointestinal complications are common after renal transplantation, and they have a wide clinical spectrum, varying from diarrhoea to post-transplant inflammatory bowel disease (IBD). Chronic immunosuppression may increase the risk of post-transplant infection and medication-related injury and may also be responsible for IBD in kidney transplant re-cipients despite immunosuppression. Differentiating the various forms of post-transplant colitis is challenging, since most have similar clinical and histological features. Drug-related colitis are the most frequently encountered colitis after kidney transplantation, particularly those related to the chronic use of mycophenolate mofetil, while de novo IBDs are quite rare. This review will explore colitis after kidney transplantation, with a particular focus on different clinical and histological features, attempting to clearly identify the right treatment, thereby improving the final outcome of patients.

Drug-Induced Small Bowel Injury: a Challenging and Often Forgotten Clinical Condition

PURPOSE OF REVIEW

Most drugs are given by the oral route. Oral intake allows direct contact between the drug and the entire GI tract mucosa, exposing it to potential topical damage until absorption. Medication-induced GI symptoms and lesions are therefore commonly encountered in clinical practice. This review will examine the most common drugs or classes of drugs affecting small bowel function and/or structure.

RECENT FINDINGS

Since non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used medicines, NSAID enteropathy is highly prevalent and brings about considerable morbidity. Antimicrobials and proton-pump inhibitors profoundly modify intestinal microbiota, affecting gut sensory and motor functions, while other drugs (like iron and gold derivatives) impair intestinal permeability. Olmesartan (and likely ACE inhibitors) induce villous atrophy and consequent malabsorption. Mycophenolate mofetil, cancer chemotherapeutic agents, and immune checkpoint inhibitors cause intestinal inflammation, abdominal pain, and diarrhea. Potassium chloride supplements may induce small bowel ulceration, stenosis, and perforation while the cotraceptive pill and anticoagulants are associated with intestinal ischemia and spontaneous intramural hematoma, respectively. In clinical practice, a deep knowledge of clinical pharmacology and toxicology and a high degree of suspicion of drug-related adverse events are mandatory. Only then, the practicing physician will be able to diagnose medication-induced small bowel lesions correctly and will implement the best strategies to treat them.

Adverse effects of mycophenolic acid in renal transplant recipients: gender differences

Background Mycophenolic acid is widely used immunosuppressive drug, associated with adverse effects which increase patient morbidity and decrease medication adherence. Objective To evaluate the adverse effects in renal transplant recipients under mycophenolate treatment with respect to gender. Setting University Clinical Centre of Nis, Clinic of Nephrology, Serbia. Method This research included 96 renal transplant recipients, who received immunosuppressive regimen, based on tacrolimus or cyclosporin A, prednisone and mycophenolic acid. The high-performance liquid chromatography method combined with protein precipitation was used for the analysis of mycophelate concentration in human plasma. Drug concentration and dose-adjusted concentration were determined with respect to the patients' gender. An adverse effect scoring system developed by nephrologists within the University of Buffalo Nephrology/Transplant Program was used to monitor adverse effects of therapy. Main outcome measure Individual and scores of adverse effects in relation to the dosing regimen and gender. Results Results showed statistically lower dose and concentrations in men compared to the women in our investigation group. Also, female patients demonstrated higher mean scores (cumulative and subscores) within the same dosing regimens of mycophenolic acid. The gastrointestinal score was significantly higher in women who received a dose greater than 720 mg compared to men (0.20 ± 0.12 vs 0.12 ± 0.12). Women demonstrated higher individual adverse effects such as diarrhea and skin changes (41.7 vs 17.0; p = 0.038 and 62.5 vs 30.2; p = 0.037, respectively). Conclusions The results of our research showed that recipients' gender may play an important role in pharmacokinetic profile of mycophenolic acid, suggesting that women had higher concentration of mycophenolic acid and more serious side effects.

Kidney transplantation in patients with inflammatory bowel diseases (IBD): analysis of transplantation outcome and IBD activity

Inflammatory bowel diseases (IBD) is a systemic disorder with possible renal involvement, yet data regarding the outcome of kidney transplantation (KT) in those patients, and IBD course post KT, are scarce. In this retrospective analysis, we studied the outcome of 12 IBD kidney recipients (seven Crohn's disease, five ulcerative colitis; primary kidney disease was IgA nephropathy in five, polycystic disease in four), compared to two control groups: matched controls and a cohort of recipients with similar kidney disease. During a follow-up period of 60.1 (11.0-76.6) months (median, interquartile range), estimated 5-year survival was 80.8 vs. 96.8%, with and without IBD, respectively (P = 0.001). Risk of death with a functioning graft was higher with IBD (HR = 1.441, P = 0.048), and with increased age (HR = 1.109, P = 0.05). Late rehospitalization rate was higher in IBD [incidence rate ratio = 1.168, P = 0.030], as well as rate of hospitalization related to infection [1.42, P = 0.037]. All patients that were in remission before KT, remission was maintained. Patients that were transplanted with mild or moderate disease remained stable or improved with Infliximab or Adalimumab treatment. In conclusion, IBD is associated with an increased risk of mortality, hospitalization because of infection and late rehospitalization after KT. Clinical course of IBD is stable after KT.

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.

Use of the National Institutes of Health Consensus Guidelines Improves the Diagnostic Sensitivity of Gastrointestinal Graft-Versus-Host Disease

CONTEXT

- Graft-versus-host disease of the gastrointestinal tract is a common complication of hematopoietic stem cell transplant associated with significant morbidity and mortality. Accurate diagnosis can be difficult and is a truly clinicopathologic endeavor.

OBJECTIVES

- To assess the diagnostic sensitivity of gastrointestinal graft-versus-host disease using the 2015 National Institutes of Health (NIH) histology consensus guidelines and to analyze histologic findings that support the guidelines.

DESIGN

- Patients with allogeneic hematopoietic stem cell transplants were identified via a retrospective search of our electronic medical records from January 1, 2005, to January 1, 2011. Endoscopies with available histology were reviewed by 2 pathologists using the 2015 NIH guidelines. The clinical diagnosis was used as the gold standard. A nontransplant set of endoscopic biopsies was used as a control.

RESULTS

- Of the 250 total endoscopies, 217 (87%) had a clinical diagnosis of gastrointestinal graft-versus-host disease. Use of the NIH consensus guidelines showed a sensitivity of 86% and a specificity of 65%. Thirty-seven of 58 (64%) cases with an initial false-negative histopathologic diagnosis were diagnosed as graft-versus-host disease on our review.

CONCLUSIONS

- Use of the NIH histology consensus guidelines results in a high sensitivity and specificity, thereby decreasing false-negatives. Additionally, use of the NIH guidelines aids in creating uniformity and diagnostic clarity. Correlation with clinical and laboratory findings is critical in evaluating the differential diagnosis and to avoid false-positives. As expected, increased apoptosis with decreased inflammation was associated with a pathologic diagnosis of graft-versus-host disease and supports the NIH guidelines.

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.

Graft-versus-Host Disease of the Gut: A Histologic Activity Grading System and Validation

The pathologic interpretation of gut biopsies in hematopoietic cell transplant recipients to assess graft-versus-host disease (GVHD) is well accepted and supplements clinical and endoscopic findings. However, the histologic activity grading of GVHD is controversial, with attempts to predict prognosis or response to treatment largely unsuccessful. GVHD is being diagnosed earlier in its course, raising the possibility that the pathologic grading system can be profitably modified. We developed a histologic activity grading system designed to replace the commonly used modified Lerner grading systems. Our system stratifies the low-level Lerner grade I category into 4 activity grade categories, based on the average frequency of apoptotic cells. The results are expressed as ordinal categories: GVHD of minimal, mild, moderate, severe histologic activity, or severe histologic activity with destruction (activity grades 1 to 5). In a retrospective study, we studied 87 consecutive cases with 201 post-transplantation specimens (median, 48 days; range, 18 to 1479 days) of stomach, duodenum, and colorectum, which had been activity graded at the time of the original diagnosis. Most of the biopsies diagnosed as GVHD were low grade-minimal (11%) or mild (71%) histologic activity. We hypothesized that the higher activity grades would be associated with more therapeutic intervention. The odds of increased therapy in the combined all-site specimens were increased as activity grade increased (odds ratio, 2.9 [95% confidence interval {CI}, 1.9 to 4.5]; P = < .0001). Thus, our grading system was validated. To investigate whether the activity grade was associated with therapy within the formerly undivided Lerner grade I category, the analysis was restricted to these 174 all-site specimens. The validation result was similar (odds ratio, 3.1 [95% CI, 1.3 to 7.2]; P = .009). This result interestingly suggests that there is useful information hidden in the Lerner grade I category, which could potentially guide immediately actionable treatment decisions. This histologic activity grade system has been in use at our institution for over 2 years with good acceptance.

Mycophenolate mofetil toxicity mimicking acute cellular rejection in a small intestinal transplant

Mycophenolate mofetil (MMF) is an important medication used for maintenance immunosuppression in solid organ transplants. A common gastrointestinal (GI) side effect of MMF is enterocolitis, which has been associated with multiple histological features. There is little data in the literature describing the histological effects of MMF in small intestinal transplant (SIT) recipients. We present a case of MMF toxicity in a SIT recipient, with histological changes in the donor ileum mimicking persistent acute cellular rejection (ACR). Concurrent biopsies of the patient’s native colon showed similar changes to those from the donor small bowel, suggesting a non-graft specific process, raising suspicion for MMF toxicity. The MMF was discontinued and complete resolution of these changes occurred over three weeks. MMF toxicity should therefore be considered as a differential diagnosis for ACR and graft-versus-host disease in SITs.

Significance of Colonoscopic Findings in Patients After Kidney Graft

OBJECTIVES

We aimed to investigate the colonoscopy findings in patients after kidney transplant.

MATERIALS AND METHODS

We retrospectively analyzed kidney transplant patients who had colonoscopy examinations for various indications between 2011 and 2015.

RESULTS

Eighty-one patients (25 women and 56 men) with a mean age of 39 years (range, 18-64 y) were identified. Mean follow-up after transplant was 9 years (range, 1-29 y). The most common indications for colonoscopy were diarrhea (41%), anemia (29%), gastrointestinal bleeding (12%), abdominal pain (12%), and unexplained weight loss (6%). Either colitis or ileitis or both were diagnosed in 20 patients (25%), whereas polyps were found in 9 patients (11%). One patient presented with hematochezia, which was diagnosed as cytomegalovirus colitis. The remaining cases of colitis or ileitis were diagnosed as nonspecific inflammation. Indications for colonoscopy were not correlated with age, duration after transplant, or use of immunosuppressive drugs. A subgroup analysis for mycophenolate-induced colitis found that 88% of patients used mycophenolate, but presence of colitis or ileitis had no statistical correlation with its use. In patients with poor gastrointestinal symptoms, the only significant predictor of presence of colitis or ileitis was a high C-reactive protein value (> 5 mg/dL; P = .02).

CONCLUSIONS

Incidence of colitis and/or ileitis is a relatively common finding in patients after kidney transplant. Opportunistic infections, mycophenolate use, and mild degree of indeterminate colitis or ileitis disease may be the underlying condition. Cytomegalovirus infection should be screened in all recipients because it may cause serious complications or death in chronically immunocompromised patients.

A Unique Case of Mycophenolate Induced Colitis after 10 Years of Use

A 31-year-old female with a history of lupus nephritis on Hydroxychloroquine, Prednisone, and Mycophenolate Mofetil (MMF) for 10 years presented to the hospital for ankle swelling. On day four, she started to have severe, nonbloody, watery diarrhea with abdominal distension and tenderness. Stool PCR was negative for C. difficile. CT abdomen/pelvis showed gaseous distension of the colon without any obstruction. Flexible sigmoidoscopy revealed a normal looking mucosa. Histopathology showed crypt atrophy and increased crypt apoptosis, consistent with MMF colitis. The diarrhea resolved three days after stopping MMF. Although generally well tolerated, diarrhea is a common side effect of MMF. Most cases occur in the first six months of starting MMF. This case is unique because it describes MMF colitis in lupus after more than 10 years. Thus, MMF colitis should be considered as a differential in patients taking it, regardless of the duration of use.

Changes in the Expression and Distribution of Claudins, Increased Epithelial Apoptosis, and a Mannan-Binding Lectin-Associated Immune Response Lead to Barrier Dysfunction in Dextran Sodium Sulfate-Induced Rat Colitis

Background/Aims

This animal study aimed to define the underlying cellular mechanisms of intestinal barrier dysfunction.

Methods

Rats were fed 4% with dextran sodium sulfate (DSS) to induce experimental colitis. We analyzed the sugars in 24-hour urine output by high pressure liquid chromatography. The expression of claudins, mannan-binding lectin (MBL), and MBL-associated serine proteases 2 (MASP-2) were detected in the colonic mucosa by immunohistochemistry; and apoptotic cells in the colonic epithelium were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method assay.

Results

The lactulose and sucralose excretion levels in the urine of rats with DSS-induced colitis were significantly higher than those in the control rats. Mannitol excretion was lower and lactulose/mannitol ratios and sucralose/mannitol ratios were significantly increased compared with those in the control group (p<0.05). Compared with the controls, the expression of sealing claudins (claudin 3, claudin 5, and claudin 8) was significantly decreased, but that of claudin 1 was increased. The expression of pore-forming claudin 2 was upregulated and claudin 7 was downregulated in DSS-induced colitis. The epithelial apoptotic ratio was 2.8%±1.2% in controls and was significantly increased to 7.2%±1.2% in DSS-induced colitis. The expression of MBL and MASP-2 in the intestinal mucosa showed intense staining in controls, whereas there was weak staining in the rats with colitis.

Conclusions

There was increased intestinal permeability in DSS-induced colitis. Changes in the expression and distribution of claudins, increased epithelial apoptosis, and the MASP-2-induced immune response impaired the intestinal epithelium and contributed to high intestinal permeability.

Histological evaluation in ulcerative colitis

This review summarizes diagnostic problems, challenges and advances in ulcerative colitis (UC). It emphasizes that, although histopathological examination plays a major role in the diagnosis and management of UC, it should always be interpreted in the context of clinical, endoscopic, and radiological findings. Accurate diagnosis requires knowledge of the classic morphological features of UC, as well as a number of atypical pathological presentations that may cause mis-classification of the disease process, either in resection or biopsy specimens. These atypical pathological presentations include rectal sparing and patchiness of disease at initial presentation of UC in pediatric patients or in the setting of medically treated UC, cecal or ascending colon inflammation in left-sided UC, and backwash ileitis in patients with severe ulcerative pancolitis. Loosely formed microgranulomas, with pale foamy histiocytes adjacent to a damaged crypt or eroded surface, should not be interpreted as evidence of Crohn's disease. Indeterminate colitis should only be used in colectomy specimens as a provisional pathological diagnosis. Patients with UC are at risk for the development of dysplasia and carcinoma; optimal outcomes in UC surveillance programs require familiarity with the diagnostic criteria and challenges relating to UC-associated dysplasia and malignancy. Colon biopsy from UC patients should always be evaluated for dysplasia based on cytological and architectural abnormalities. Accurate interpretation and classification of dysplasia in colon biopsy from UC patients as sporadic adenoma or UC-related dysplasia [flat, adenoma-like, or dysplasia-associated lesion or mass (DALM)] requires clinical and endoscopic correlation. Isolated polypoid dysplastic lesions are considered to be sporadic adenoma if occurring outside areas of histologically proven colitis, or adenoma-like dysplasia if occurring in the diseased segment. Recent data suggest that such lesions may be treated adequately by polypectomy in the absence of flat dysplasia in the patient. UC patients with DALM or flat high-grade dysplasia should be treated by colectomy because of the high probability of adenocarcinoma. The natural history of low-grade dysplasia (LGD) is more controversial: while multifocal LGD, particularly if detected at the time of initial endoscopic examination, is treated with colectomy, unifocal flat LGD detected during surveillance may be managed by close follow-up with increased surveillance. The surveillance interval and treatment options for UC patients with dysplasia are reviewed in detail.

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.

Endoscopic and histological features of mycophenolate mofetil colitis in patients after solid organ transplantation

BACKGROUND

Mycophenolate mofetil (MMF) is an immunosuppressive agent commonly used after organ transplantation. Gastrointestinal side effects occur in approximately 45% of patients. The spectrum of histologic features associated with MMF colitis has been well described, but data on the endoscopic features is lacking. The aim of the study was to describe the endoscopic features of MMF colitis in solid organ transplant recipients (SOTRs) as well as the frequency of histologic features and identify associated risk factors.

METHODS

A retrospective review of all SOTRs taking MMF and who underwent colonoscopy between 2000 and 2010 was performed. 36 cases of MMF colitis were identified and 361 patients served as controls. Descriptive statistics and data analysis looking for associated risk factors were performed.

RESULTS

Among SOTRs taking MMF who underwent colonoscopy, MMF colitis was diagnosed in 9%. Endoscopic findings ranged from erythema (33%) to erosions/ulcers (19%). 47% of patients had a normal colonoscopy and everyone had rectal sparing. Histological findings included acute colitis-like findings (50%), inflammatory bowel disease-like characteristics (36%), ischemia-like findings (5.6%), and graft-versus-host disease-like features (8.3%). Diarrhea occurred in 83%. Kidney transplantation was associated with a higher risk of MMF colitis (OR 5.8 [2.86-11.86], P<0.0001) whereas liver transplantation was associated with a lower risk (OR 0.06 [0.03-0.16], P<0.0001).

CONCLUSION

MMF colitis is fairly prevalent in SOTRs taking MMF who undergo colonoscopy. Diarrhea is the most common reason for colonoscopy referral (83%) and up to 47% of patients have normal colonoscopy, suggesting the need for routine biopsies to help confirm the diagnosis.