Mycophenolate mofetil-induced colonic ulceration in renal transplant recipients

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.

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.

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.

Sirolimus and mycophenolate mofetil as GVHD prophylaxis in myeloablative, matched-related donor hematopoietic cell transplantation

We investigated sirolimus and mycophenolate mofetil (MMF) as graft-versus-host disease (GVHD) prophylaxis in patients with advanced hematologic malignancies receiving myeloablative hematopoietic cell transplantation (HCT) from HLA-identical sibling donors. Based on pre-study stopping rules, the trial was closed to accrual after enrollment of 11 adult patients. Seven of the 11 patients received busulfan-containing preparative regimens. Sirolimus was discontinued in 3 patients due to toxicity-related events of severe sinusoidal obstructive syndrome, portal vein thrombosis, altered mental status and in 1 patient due to risk of poor wound healing. Six of the 11 patients developed grade II-IV acute GVHD (AGVHD) a median of 15.5 days post-HCT. Two of 3 patients with grade IV AGVHD had sirolimus discontinued by 9 days post-HCT. All patients responded to AGVHD therapy without GVHD-related deaths. There were 2 nonrelapse- and 2 relapse-related deaths. At a median follow-up of 38 months (2–47 months), 7 of 11 patients were alive without disease. MMF and sirolimus GVHD prophylaxis did not reduce the risk of acute GVHD, however, there were no GVHD-related deaths. The severe toxicities in the patients receiving the busulfan-containing preparative regimens limited the continued use of sirolimus and MMF for the prevention of AGVHD.

Mycophenolate mofetil-related gastrointestinal mucosal injury in multivisceral transplantation

Mycophenolate mofetil (MMF) has become an important and commonly used drug for maintenance immunosuppression therapy in recipients of all types of organ transplants. The drug is an antimetabolite that blocks the de novo pathway of purine synthesis. Although it selectively inhibits B- and T-lymphocyte proliferation, enterocytes are partially susceptible to MMF. One of the main limitations of this drug is gastrointestinal toxicity, with diarrhea the most frequently reported adverse effect. Most studies of MMF-associated gastrointestinal toxicity have been performed in patients with solid-organ transplants, although no data on changes related to MMF toxicity in bowel allografts have been published in the English literature. We evaluated mucosal intestinal biopsy tissue from patients with multivisceral transplants receiving MMF therapy. Our objective was to find morphologic changes that might be attributed to MMF toxicity, as well as changes that could differentiate MMF toxicity from acute rejection. Examination of the surface epithelium, lamina propria, and crypts in this small group of patients showed no specific changes that could be associated with MMF toxicity. Changes such as graft-vs-host disease or inflammatory bowel disease described in previous studies of solid-organ transplantation were not observed. Larger studies and the use of special stains and new markers might be necessary to characterize possible patterns of MMF toxicity and their differences from acute rejection.

Mycophenolate mofetil-related gastrointestinal mucosal injury: variable injury patterns, including graft-versus-host disease-like changes

Mycophenolate mofetil (MMF) is a commonly used immunosuppressive drug used in the management of transplant recipients. Although gastrointestinal (GI) toxicity is a known complication of MMF, the literature characterizing the pathologic features of MMF in the GI tract is sparse. This study characterizes the pathologic features of MMF toxicity in both the upper and lower GI tract, correlating it with clinical and endoscopic findings. Seventy-five GI biopsies (9 esophageal, 15 gastric, 16 duodenal, 5 ileal, 30 colonic) from 46 transplant recipients from 2002 to 2006 were obtained and assessed for multiple histologic features. Clinical features were recorded for all cases and endoscopic findings. Only MMF patients showed ulcerative esophagitis (5/7 cases) and reactive gastropathy (4/10 cases). Only MMF patients showed graft-versus-host disease (GVHD)-like features in duodenal (4/12 cases) and ileal (1/5 cases) biopsies. GVHD-like changes were seen more frequently among patients on MMF compared with those not on MMF [9 (56%) vs. 2 (14%); P=0.017]. Crypt architectural disarray [12 (75%) vs. 2 (14%); P=0.001], lamina propria edema [9 (56%) vs. 2 (14%); P=0.017], increased lamina propria inflammation [13 (81%) vs. 3 (21%); P=0.001], dilated damaged crypts [7 (44%) vs. 1 (7%); P=0.024], and increased crypt epithelial apoptosis [9 (56%) vs. 2 (14%); P=0.017] were more common with MMF patients compared with non-MMF patients. In conclusion, pathologists should be aware of the potential manifestations of MMF toxicity throughout the GI tract, including ulcerative esophagitis, reactive gastropathy, and GVHD-like features in intestinal biopsies.

Insulin-like growth factor I improves aspects of mycophenolate mofetil-impaired anastomotic healing in an experimental model

Background

Patients taking immunosuppressants after transplantation may require intestinal surgery. Mycophenolate mofetil (MMF) has been found to impair the healing of colonic anastomoses in rats. This study examined whether insulin-like growth factor (IGF) I prevents MMF impairment of anastomotic healing.

Methods

Sixty-three rats were divided into three groups (MMF, MMF/IGF and control). Animals underwent a sigmoid colon anastomosis with a 6/0 suture, and were killed on days 2, 4 and 6 after surgery. Investigations included bursting pressure measurement, morphometric analysis, and assessment of mucosal proliferation by 5-bromo-2′-deoxyuridine and Ki67 immunohistochemistry of the anastomoses.

Results

The leak rate was three of 21, one of 20 and two of 20 in the MMF, MMF/IGF-I and control groups respectively. Anastomotic bursting pressures were significantly lower in the MMF group than in the control group on days 2 and 4, but there was no significant difference by day 6. Values in the MMF/IGF-I and control groups were similar. Colonic crypt depth was significantly reduced in MMF-treated animals on days 2 and 4, but this impairment was attenuated by IGF-I on day 4. Similarly, IGF-I reduced the negative impact of MMF on mucosal proliferation on days 2 and 6.

Conclusion

Exogenous IGF-I improves some aspects of MMF-impaired anastomotic healing.

Application of prodrugs to inflammatory diseases of the gut

Oral delivery is the most common and preferred route of drug administration although the digestive tract exhibits several obstacles to drug delivery including motility and intraluminal pH profiles. The gut milieu represents the largest mucosal surface exposed to microorganisms with 10^10-12 colony forming bacteria/g of colonic content. Approximately, one third of fecal dry matter is made of bacteria/ bacterial components. Indeed, the normal gut microbiota is responsible for healthy digestion of dietary fibers (polysaccharides) and fermentation of short chain fatty acids such as acetate and butyrate that provide carbon sources (fuel) for these bacteria. Inflammatory bowel disease (IBD) results in breakage of the mucosal barrier, an altered microbiota and dysregulated gut immunity. Prodrugs that are chemically constructed to target colonic release or are degraded specifically by colonic bacteria, can be useful in the treatment of IBD. This review describes the progress in digestive tract prodrug design and delivery in light of gut metabolic activities.

Crohn's-like changes in the colon due to mycophenolate?

OBJECTIVE

Mycophenolate mofetil (MMF) is used for prevention of allograft rejection in kidney transplant patients. A subset of patients suffers from chronic diarrhoea of unknown origin. The aim of the study was to investigate the effect of MMF on the colonic mucosa.

MATERIALS AND METHODS

Colonic mucosal biopsies from 24 kidney transplant patients receiving MMF and presenting with chronic diarrhoea were analysed using routine stainings and immunohistochemistry for Ki67 and E-cadherin. Results were compared with a control group of 19 kidney transplant patients not receiving MMF. In all patients routine clinical and laboratory investigations were performed in order to explain the diarrhoea.

RESULTS

In 11 patients, the diarrhoea seemed to be of infectious origin. Furthermore, 19/24 of MMF-patients showed characteristic histological alterations of the mucosa that were Crohn's disease-like: discontinuous crypt architectural distortion, increased epithelial mucin secretion, mildly active inflammation and focal presence of dilated and inflamed crypts. Ki67 staining was abnormal in 6/24 MMF patients but also in 4/19 control patients. E-Cadherin staining was normal in most MMF and control patients.

CONCLUSIONS

Diarrhoea following MMF treatment is frequently infectious in origin and associated with morphological changes with a Crohn's-like pattern in the colonic mucosa in a subset of patients. MMF does not induce major alteration in the proliferative compartment of colonic epithelium. The diarrhoea is not associated with altered E-cadherin expression in the colonic epithelium.

Cyclosporine, tacrolimus, and mycophenolate mofetil in the treatment of inflammatory bowel disease

In the past decade, immunosuppressive drugs have come to play an integral role in the treatment of patients with inflammatory bowel disease. Cyclosporine, microemulsion cyclosporine, tacrolimus, and mycophenolate mofetil can be considered for the treatment of patients with refractory inflammatory Crohn's disease, fistulizing Crohn's disease, and severe ulcerative colitis. This article reviews the use of cyclosporine, tacrolimus, and mycophenolate mofetil in patients with inflammatory bowel disease, with emphasis on pharmacology, results in controlled clinical trials, and safety, and issues related to dosing and toxicity monitoring.

Histological changes after the use of mycophenolate mofetil in autoimmune hepatitis

Corticosteroids and azathioprine are considered standard treatment for autoimmune hepatitis. There are, however, well-known systemic side effects that may preclude continuation with these immunosuppressive therapies, and small trials of the anti-metabolite mycophenolate mofetil have been reported. We report liver biopsy findings in a follow-up biopsy of a patient who had been switched from azathioprine to mycophenolate mofetil for treatment of presumed, steroid-responsive autoimmune hepatitis. Both cytoplasmic features of adaptation and nuclear alterations were noted in hepatocytes. Possible mechanisms for these findings are discussed.

Histologic features of mycophenolate mofetil-related colitis: a graft-versus-host disease-like pattern

Mycophenolate mofetil (MMF) is widely used for maintenance immunosuppression in solid organ transplantation. Gastrointestinal toxicity, usually manifested as diarrhea, is the most common side effect of MMF. We evaluated colonic biopsies from 20 renal transplant patients with MMF-related diarrhea. The latter was defined by the absence of any other demonstrable etiology and improvement or resolution of symptoms by the discontinuation or reduction of the dose of MMF alone. These biopsies were compared with colon biopsies from patients with the following: acute graft-versus-host disease (GVHD, n=10), inflammatory bowel disease (IBD) or infectious colitis (n=10), and colon biopsies from renal transplant patients not receiving MMF (n=8). Normal colonic segments from surgical specimens served as normal controls (n=5). Colonic biopsies from patients with MMF-related diarrhea showed prominent crypt cell apoptosis and reactive/reparative changes including enterocyte cytologic atypia, increased neuroendocrine cells, and glandular architectural distortion. The changes were similar, although of milder degree to the ones seen in patients with acute intestinal GVHD. This pattern of injury was not seen in controls or in biopsies from transplant patients not receiving MMF, and it was markedly different from the one seen in idiopathic inflammatory or infectious colitis. The severity of histologic changes correlated significantly with the endoscopic degree of "colitis." There was no statistically significant correlation between histologic damage and the dose of MMF (corrected for body weight and renal function). MMF-related colitis is a distinct entity that displays histologic features remarkably similar to the ones associated with intestinal GVHD. This form of injury could be related to either direct toxicity or an "innocent by-stander" phenomenon secondary to the alteration of the immunologic microenvironment of the colon caused by the MMF.

Toxicity of mycophenolate mofetil in patients with inflammatory bowel disease

Trials of mycophenolate mofetil (MMF) in inflammatory bowel disease (IBD) suggest that it may be useful in patients intolerant of azathioprine. We examined the safety and efficacy of MMF in IBD patients intolerant of or unresponsive to azathioprine. Twelve patients [seven with Crohn's disease (CD); seven women; mean age 40 years, range 14-76 years] were treated with MMF 500 mg b.i.d. for a mean of 12.5 weeks. Intolerance was defined as the development of side effects that resolved on discontinuing MMF. Improvement was described as symptomatic improvement, decreased steroid use, or disease entering endoscopic remission. Four patients responded with symptomatic improvement and reduced steroids or mesalazine requirement. Three patients developed headache, nausea, or arthralgia. Three patients developed profuse bloody diarrhea, and in two cases with previously quiescent ulcerative colitis (UC), the source was shown to be ulcers in a drug-induced colitis with histologic features similar to those previously reported in four renal transplant patients on MMF. There is no clear evidence of efficacy of MMF in the treatment of IBD, and its use in this condition should be confined to a randomized controlled trial. Moreover, as patients with UC may be unduly prone to colonic injury, MMF may not be a suitable drug for its treatment.

Mycophenolate mofetil impairs healing of left-sided colon anastomoses

INTRODUCTION

Inadequate healing and consequent leakage from bowel anastomoses are a significant cause of postoperative morbidity and mortality. Immunosuppressive drugs are known to disturb healing processes and to impair the mechanical stability of bowel anastomosis. Mycophenolate mofetil (MMF) is an immunosuppressive agent that selectively inhibits the proliferation of T and B lymphocytes and has been shown to be effective in preventing allograft rejection after organ transplantation. Adverse effects are few; however, nothing is known in regard to possible adverse effects of MMF administration on the healing of bowel anastomosis. The aim of the present study was to evaluate the effect of systemic MMF administration on the healing of colon anastomoses in rats.

METHODS

Rats underwent laparotomy, division of the left colon, and sigmoidostomy. MMF (25 mg/kg) or vehicle was administered intraperitoneally in two groups (n=21 per group) 3 days before surgery and then once daily until euthanization (7 animals per group; 2, 4, and 6 days after surgery). Bursting pressure measurements, histologic evaluation, morphometric analysis, mucin and collagen staining, and BrdU immunohistochemistry of the anastomotic site were performed. Furthermore, matrix protein expression at the anastomotic site was determined by collagen I and fibronectin Western blots.

RESULTS

Administration of MMF significantly decreased anastomotic bursting pressure postoperatively. Accordingly, histology, mucin staining, and BrdU immunohistochemistry and measurements of the colonic crypt depth showed more extended inflammation, a significantly lower proliferation rate, and a significantly thinned mucosal layer in the MMF-treated groups when compared to control animals, whereas matrix synthesis at the anastomotic site was not different.

CONCLUSIONS

The administration of the immunosuppressive agent MMF significantly impairs healing and mechanical stability of colon anastomosis in rats during the early postoperative period. MMF act to disturb host reparative processes mainly by impairment of reparative colonic epithelium proliferation and less by a disturbance of matrix synthesis.

Induction of cytokine release by the acyl glucuronide of mycophenolic acid: a link to side effects?

OBJECTIVES

We have identified an acyl glucuronide (M-2) of the immunosuppressant mycophenolic acid (MPA). Acyl glucuronides have toxic potential and may contribute to drug toxicity. Whether acyl glucuronides are able to induce release of proinflammatory cytokines is unknown. Gastrointestinal disturbances have been observed during MPA therapy and may involve an inflammatory reaction. This study investigated whether M-2 can induce IL-6 and TNF-alpha release as well as gene expression of these cytokines in leukocytes.

DESIGN AND METHODS

M-2 was produced by incubation of MPA with human liver microsomes. Human mononuclear leukocytes were incubated in the presence of M-2. Concentrations of IL-6 and TNF-alpha were measured by ELISA. Expression of mRNA was determined by quantitative RT-PCR.

RESULTS

Incubation of 3 x 10(6) cells with M-2 resulted in a time and dose dependent release of cytokines, whereas MPA or its phenolic glucuronide MPAG were without effect. Cytokine liberation depended on mRNA induction. Response to M-2 showed much inter individual variability (30-fold for IL-6, 3-fold for TNF-alpha).

CONCLUSIONS

If M-2 promotes release of cytokines in vivo, these may mediate some of the toxic actions of MPA.

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.