Two cases of severe de novo colitis in kidney transplant recipients after conversion to prolonged-release tacrolimus

Drug-induced digestive tract injury: decoding some invisible offenders

There is an ever-growing list of pharmacological agents, several of which are attributed to cause clinically significant gastrointestinal (GI) injury. Many patients present with significant but nonspecific symptoms, that in conjunction with the absence of relevant drug history on the requisition slip can make the histopathologic diagnosis challenging. To complicate this, although some drugs have relatively characteristic histopathologic features (such as doxycycline), there exist many other drugs that exhibit wide and varying spectra of histopathologic findings (such as immune checkpoint inhibitors or olmesartan) and have histomorphologic overlap with many other commonly encountered disease entities. This review discusses the histopathologic features of some relatively recently described drugs causing GI tract injury, namely doxycycline, tacrolimus, mycophenolate, immune checkpoint inhibitors, and olmesartan. We also discuss the common mimics in histopathologic differential and some pearls that can help distinguish GI tract injury induced by the aforementioned drugs from its mimics. Awareness of the wide spectra of histopathologic changes associated with these drugs is crucial for practicing pathologists, to avoid misdiagnosis and guiding the clinician for an optimal patient management, which usually involves modifying or discontinuing the offending drug. Needless to say, once a diagnosis of drug-induced injury is suspected, clinicopathologic correlation including corroboration with the drug history is of utmost importance as is the exclusion of dual pathology in these patients.

Therapeutic agents affecting the immune system and drug-induced inflammatory bowel disease (IBD): A review on etiological and pathogenetic aspects

In recent years, therapeutic agents affecting the immune system have been largely implemented in the treatment of various hematological, rheumatological and dermatological disorders. Their clinical use has offered important benefits for affected patients and has also ameliorated clinical outcome and prognosis in many cases. Nonetheless, as any treatment, the use of these drugs may be associated with side effects. One of the target organs in such cases is the gastrointestinal tract. In particular, the exacerbation or the onset of inflammatory bowel disease (IBD) in treated patients is not infrequent, although the mechanism of action of these agents may be different. In this review we will focus on the use of therapeutic agents affecting the immune system and the development or exacerbation of IBD, with a mention on the possible underlying pathogenetic mechanisms.

Drug-Induced Colitis

Drug-induced colitis encompasses a wide spectrum of colon disorders that can manifest microscopically or macroscopically. Patients present with new-onset colitis or exacerbations of inflammatory bowel diseases; in some cases, colitis resolves with discontinuation of medication. Mucosal injury can be focal or extensive, involving the entire colonic mucosa, and sometimes involves other parts of the gastrointestinal tract. It has been a challenge to determine the proportion of new-onset colitis caused by medication and there are few data on the overall prevalence. We review the drugs that have been linked with development of drug-induced colitis and strategies for physicians who believe their patients have this disorder-usually discontinuation of the drug believed to cause colitis and treatment with steroids or immune-modulating therapies. Physicians must be aware of medications that can cause colitis.

Histologic Features of Tacrolimus-induced Colonic Injury

Tacrolimus is a common immunosuppressant used in solid organ transplant recipients. Although most patients develop diarrheal symptoms, data regarding patterns of injury in patients taking tacrolimus are limited. We performed this study to characterize tacrolimus-related features of colonic injury. We retrospectively identified colonic samples from 20 patients receiving tacrolimus monotherapy. Records were reviewed for symptoms, endoscopic findings, other medications, and infections. None of the patients had gastrointestinal infections or used other drugs known to cause colonic injury; none had received mycophenolate within 6 months of presentation. Cases were evaluated for the nature and distribution of inflammation and crypt abnormalities, including distortion, destruction, and apoptosis. Eighteen (90%) patients were solid organ transplant recipients. Seventeen (85%) had gastrointestinal symptoms, particularly diarrhea (75%). More than 50% had endoscopic colitis and 15% had ulcers and/or erosions. Most (90%) cases showed regenerative epithelial changes; apoptotic crypt cells were present in 55% and numerous in 10% of cases. Neutrophilic cryptitis was present in 60% of cases; 35% showed crypt destruction. Plasma cell-rich lamina propria inflammation and crypt distortion were observed in 40% and 25% of cases, respectively. There was no correlation between therapy duration and features of chronic injury. We conclude that tacrolimus can cause symptomatic colitis. Histologic abnormalities are often mild, featuring regenerative crypts and scattered apoptotic debris. However, 40% of symptomatic patients have chronic colitis, most likely reflecting drug-induced immune dysregulation. Pathologists should be aware of these associations because colitis often resolves with decreasing drug dosage rather than treatment directed toward inflammatory bowel disease.

De novo ulcerative colitis after kidney transplantation treated with infliximab

Diarrhea is a common complication in kidney transplant recipients. Common causes of diarrhea include infection, side effect from medication, rejection, and malignancy. A less common but important cause of diarrhea is de novo inflammatory bowel disease (IBD). This is unexpected, as these patients are already immunosuppressed. Herein, we present the case of a 45-year-old man with end-stage kidney disease because of focal segmental glomerulosclerosis who underwent preemptive kidney transplantation, with his mother as donor. His immunosuppressive regimen included methylprednisolone, mycophenolate mofetil, and tacrolimus. He had no episodes of graft dysfunction, rejection, or infectious events. Two and a half years post-transplantation, he developed bloody diarrhea. After excluding infections, colonoscopy was performed and revealed edematous mucosa and erythema with pigmentation, which are typical findings in ulcerative colitis. Despite therapy with 5-aminosalicylate and granulocyte monocyte apheresis, he presented with massive bloody diarrhea. We initiated infliximab, an anti-tumor necrosis factor-α (TNF-α) agent. He responded very well and achieved remission within 6 months after initiation of infliximab, while administration of the other immunosuppressants was maintained. His course was uneventful and no complications developed. Management of immunosuppressants for de novo IBD after organ transplantation is complicated, because treatment of IBD, graft function protection, and prevention of infection must be considered. Therefore, cooperation between transplantation physicians and gastroenterologists is essential during therapy.

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.

Bioresponsive nanostructured systems for sustained naltrexone release and treatment of alcohol use disorder: Development and biological evaluation

In this study, microemulsions capable of transforming into nanostructured hexagonal phase gels in vivo upon uptake of biological fluids for naltrexone prolonged release were investigated as a strategy for management of alcohol use disorder (AUD). Microemulsions were prepared using monoolein, tricaprylin, water and propylene glycol; after preliminary characterization, one formulation was selected, which contained 55% of monoolein-tricaprylin (M-55). This microemulsion displayed size below 200 nm and Newtonian rheological behavior. Liquid crystalline gels formed in vitro upon 8 h of contact with water following a second order kinetics. After 120 h, <50% of naltrexone was released in vitro independently on drug loading (5 or 10%). In vivo, gels formed within 24 h of M-55 subcutaneous administration, and persisted locally for over 30 days providing slow release of the fluorescent marker Alexa fluor compared to a solution. Using the conditioned place preference paradigm, a test used to measure drug's rewarding effects, a single dose of M-55 containing 5% naltrexone reduced the time spent in the ethanol-paired compartment by 1.8-fold compared to saline; this effect was similar to that obtained with daily naltrexone injections, demonstrating the formulation efficacy and its ability to reduce dosing frequency. A more robust effect was observed following administration of M-55 containing 10% of naltrexone, which was compatible with aversion. These results support M-55 as a platform for sustained release of drugs that can be further explored for management of AUD to reduce dosing frequency and aid treatment adherence.

Secondary causes of inflammatory bowel diseases

Inflammatory bowel diseases (IBD), conventionally consist of Crohn’s disease (CD) and ulcerative colitis. They occur in individuals with high risk genotype for the disease in the setting of appropriate environmental factors. The pathogenesis of IBD involves a dysregulated autoimmune response to gut dysbiosis, which in turn is triggered due to exposure to various inciting environmental factors. But there is no clearly defined etiology of IBD and this type of disease is termed as “idiopathic IBD”, “classic IBD”, or “primary IBD”. We reviewed the current medical literature and found that certain etiological factors may be responsible for the development of IBD or IBD-like conditions, and we consider this form of de novo IBD as “secondary IBD”. Currently known factors that are potentially responsible for giving rise to secondary IBD are medications; bowel altering surgeries and transplantation of organs, stem cells or fecal microbiome. Medications associated with the development of secondary IBD include; immunomodulators, anti-tumor necrosis factor alpha agents, anti-interleukin agents, interferons, immune stimulating agents and checkpoint inhibitors. Colectomy can in some cases give rise to de novo CD, pouchitis of the ileal pouch, or postcolectomy enteritis syndrome. After solid organ transplantation or hematopoietic stem cell transplantation, the recipient may develop de novo IBD or IBD flare. Fecal microbiota transplantation has been widely used to treat patients suffering from recurrent Clostridium difficile infection but can also causes IBD flares.

Conversion From Cyclosporine to Once-Daily Tacrolimus on 50:1 mg Basis: A Short-Term Pilot Study

OBJECTIVES

In addition to graft dysfunction, renal transplant recipients on cyclosporine may be switched to tacrolimus to reduce its drug-related secondary clinical effects and undesirable cosmetic side effects. However, the dose level of once-daily tacrolimus for these patients has yet to be established. The objective of this prospective study was to confirm the safety of converting stable renal transplant recipients on cyclosporine to once-daily tacrolimus at a 50:1 mg ratio.

MATERIALS AND METHODS

Our study enrolled 17 patients receiving cyclosporine who were observed for 3 months. Graft biopsies did not reveal any acute rejection, and the conversion ratio to once-daily tacrolimus was 50:1 mg. Dose adjustments were made to achieve a target tacrolimus trough concentration of 3 to 5 ng/mL at 2 weeks, and graft biopsies were taken after the 3-month observation period.

RESULTS

Dose adjustment was required in 7 recipients (41.2%) within 3 months of conversion. None of the recipients had acute cellular rejection or C4d deposition, and the mean estimated glomerular filtration rate of 38.7 ± 11.0 mL/min/1.73 m2 at baseline was significantly improved to 42.0 ± 10.0 mL/min/1.73 m2 at month 3.

CONCLUSIONS

Although recipients of renal transplant can be forced to discontinue cyclosporine administration due to undesirable adverse effects, our study showed that a once-daily dose of tacrolimus may be safe when administered at a conversion ratio of 50:1.

Differentiating Posttransplant Inflammatory Bowel Disease and Other Colitides in Renal Transplant Patients

Renal transplant recipients who present with gastrointestinal complaints may have symptoms related to their underlying renal disease or secondary to their immunosuppressive regimen. Immunosuppression increases patients' risk for infection and medication-induced injury, and a subset of transplant patients develop a form of inflammatory bowel disease (IBD) despite being immunosuppressed. In this study, we present the spectrum of changes in colonic biopsy histology that occur in the postrenal transplant population, with emphasis on the clinical and histologic features that may allow distinction between several common disorders. Over a 15-year period, 51 postrenal transplant patients underwent colonoscopy with biopsy. Eleven (22%) patients had infectious colitis, and 10 of these had biopsy proven acute colitis. Another 17 (33%) patients were determined to have a medication-related injury based on resolution of symptoms following drug cessation. The majority (53%) of these colonic biopsies demonstrated crypt epithelial cell apoptosis and/or architectural distortion, although 41% were histologically normal. Four (8%) patients were ultimately diagnosed with a form of IBD after exclusion of other etiologies; biopsies from these patients demonstrated chronic active colitis or enteritis with plasma cell-rich expansion of the lamina propria and basal lymphoplasmacytosis. The increased prevalence of IBD in this patient cohort (4/700) compared with that reported in the overall North American population (1 to 2/700) is in line with prior studies and is likely related to the therapeutic regimen and associated immune dysregulation that occurs in solid-organ transplant recipients. We demonstrate that a combination of clinical, endoscopic, and histologic features are useful to distinguish among causes of gastrointestinal symptoms in this high risk population.

Efficacy and safety of conversion from twice-daily to once-daily tacrolimus in a large cohort of stable kidney transplant recipients

Prolonged-release tacrolimus was developed to provide a more convenient once-daily dosing that could improve patient adherence. We conducted a multicenter, prospective, observational, 12-month study to describe the efficacy, safety and patient preference of conversion from tacrolimus twice-daily to once-daily formulation in stable kidney transplant recipients in routine clinical practice. Conversion was made on a 1 mg: 1 mg basis (1 mg: 1.1 mg in patients with trough levels <6 ng/mL). The study included 1832 patients (mean age (± SD): 50.0 ± 13.4 years; 62.7% male). After conversion, a modest reduction in tacrolimus trough levels, necessitating an increase in daily dose, was observed (mean changes at 12 months of -9.1% and +1.24%, respectively; p < 0.0001). Mean glomerular filtration rate did not change significantly (56.5 ± 19.7 mL/min at conversion vs. 55.7 ± 20.6 mL/min at 12 months). Proteinuria, blood pressure, lipid, hepatic and glucose parameters remained stable. Eight patients (0.4%) had acute rejection and 34 patients (1.85%) discontinued treatment. Almost all patients (99.4%) preferred the once-daily formulation, because of less frequent dosing (66%) and improved adherence (34%). In conclusion, at similar doses to twice-daily tacrolimus, once-daily formulation provided stable renal function, a low acute rejection rate, and good tolerability in stable kidney transplant recipients in the routine clinical practice setting.