Intestinal thrombotic microangiopathy induced by FK506 in rats

Temporary decrease in tacrolimus clearance in cytochrome P450 3A5 non-expressors early after living donor kidney transplantation: Effect of interleukin 6-induced suppression of the cytochrome P450 3A gene

Tacrolimus is important for immunosuppression in kidney transplantation. In this historical cohort and in vitro study, we evaluated the changes in tacrolimus pharmacokinetics early after living donor kidney transplantation and the effects of interleukin (IL)-6 on cytochrome P450 3A4 (CYP3A4) and cytochrome P450 3A5 (CYP3A5) expression. In the historical cohort study, 22 patients who met the inclusion criteria were classified into CYP3A5 expressors and non-expressors (n = 16 and 6, respectively). The blood tacrolimus concentration per dose ratio (C/D) temporarily increased post-kidney transplantation on days 3-4 only in CYP3A5 non-expressors. The effects of IL-6 on CYP3A4 and CYP3A5 expression were also investigated in vitro using HepG2 and Caco-2 cells. IL-6 induced a significant concentration- and time-dependent decrease in CYP3A4 and CYP3A5 expression in both cells. The mean CYP3A4 expression level at 12 hours after IL-6 exposure (% of 0 hour) was 44.0 and 62.6 in HepG2 and Caco-2 cells, respectively, whereas the CYP3A5 expression level was 30.7 and 52.4, respectively. We hypothesize that CYP3A5 non-expressors might exhibit a temporary decrease in the oral clearance of tacrolimus via an increase in serum IL-6 concentrations early after kidney transplantation. These results may help develop strategies to improve kidney transplant outcome.

Higher Peak Tacrolimus Concentrations after Allogeneic Hematopoietic Stem Cell Transplantation Increase the Risk of Endothelial Cell Damage Complications

Noninfectious transplantation-related complications (TRCs) such as graft-versus-host disease (GVHD) and endothelial cell damage (TRC-EC) are critical after allogeneic hematopoietic stem cell transplantation. Tacrolimus (TAC) is used to control GVHD. Hypertension and renal failure are common adverse events after TAC treatment. Higher blood concentrations of TAC would be expected to reduce the risk of GVHD but may increase TRC-EC. TRC-EC often develops in patients with GVHD; thus, it is difficult to clinically determine the proper intensity of immunosuppression. We therefore evaluated the impact of weekly mean/peak TAC blood concentrations (PTCs) on TRC-EC occurrence and prognosis. Patients (N = 295) who received TAC as a GVHD prophylaxis at our institute from 2009 to 2016 were eligible for this retrospective study. Forty-three patients were diagnosed with TRC-EC: 8 with sinusoidal obstructive syndrome, 28 with transplant-associated microangiopathy, and 7 with idiopathic pneumonia syndrome. The cumulative incidence of TRC-EC at 12 months was 13.8% (95% confidence interval [CI] 10.1% to 18.1%). After multivariate analysis high PTCs during days 22 to 28 (hazard ratio [HR] 2.47; 95% CI, 1.37 to 4.45; P < .01) and grades II to IV acute GVHD (HR, 5.61; 95% CI, 2.99 to 10.53; P < .01) were associated with TRC-EC occurrence. The probability of overall survival (OS) at 12 months was 67.7% (95% CI, 61.7% to 73.0%). After multivariate analysis TRC-EC diagnosis (HR, 2.47, 95% CI, 1.59 to 3.83; P < .01) and high-risk disease (HR, 1.75; 95% CI, 1.17 to 2.61; P < .01) were significantly associated with poor OS. In conclusion, higher PTC during days 22 to 28 increased the risk of TRC-EC. TRC-EC development was associated with poor OS.

Bone marrow transplant-associated thrombotic microangiopathy without peripheral blood schistocytes: a case report and review of the literature

Background

Bone marrow transplant-associated thrombotic microangiopathy (TA-TMA) is a relatively frequent but under-recognized and under-treated hematopoietic stem cell transplant (HSCT) complication that leads to significant post-transplant morbidity and mortality. Classic TMA-defining laboratory abnormalities appear at different times in the course of TA-TMA development, with schistocytes often appearing later in the disease course. In some severe TMA cases, schistocytes may be absent due to increased endothelial permeability. Unfortunately, many clinicians continue to perceive the presence of schistocytes as an absolute requirement for TA-TMA diagnosis, which leads to delayed recognition and treatment of this potentially fatal transplant complication.

Methods

Patient chart review and PubMed literature search using the term, "transplant-associated thrombotic microangiopathy".

Case presentation

A 54-year-old male IgG kappa multiple myeloma underwent a reduced intensity allogeneic HSCT from a 9/10 HLA-matched unrelated donor after conditioning with fludarabine and melphalan. On day + 27, the patient developed acute kidney injury followed by repeated episodes of diarrhea and gastrointestinal bleeding attributed to graft versus host disease (GVHD) and cytomegalovirus (CMV) colitis. Repeated colonic biopsies suggested CMV infection and GVHD. Despite appropriate treatment with antiviral therapy and immunosuppressants, the patient's condition continued to deteriorate. He experienced concomitant anemia and thrombocytopenia as well as elevated lactate dehydrogenase and low haptoglobin levels, but a TA-TMA diagnosis was not made due to an absence of schistocytes on peripheral smear. The patient expired secondary to uncontrolled gastrointestinal bleeding. A post-mortem analysis of the resection specimen revealed extensive TMA involving numerous arteries and arterioles in the ileal and colonic submucosa as well as in the muscularis propria and deep lamina propria of the mucosa.

Conclusions

TA-TMA can occur in the absence of peripheral blood schistocytes. Our experience underscores the importance of considering the diagnosis of intestinal TA-TMA in patients with refractory post-transplant diarrhea and GI bleeding, even if all classic features are not present.

Successful Treatment of a Case of Late-onset Colitis after Umbilical Cord Transplantation with Metronidazole: A Case Report and Literature Review

Diarrhea after hematopoietic stem cell transplantation (HSCT) can be life-threatening, and its etiology includes conditioning regimens, graft-versus-host disease (GVHD), infections, and transplantation-associated microangiopathy (iTAM). Cord colitis syndrome (CCS) has been described as a syndrome of culture-negative and antibiotic-responsive persistent watery and non-bloody diarrhea of uncertain pathogenesis and occurs in umbilical cord blood transplantation (UCBT) recipients. We encountered a case similar to CCS that developed severe watery diarrhea after UCBT without any signs of GVHD or infection and responded well to metronidazole (MNZ) treatment. Since CCS is very rare, we herein describe a case of MNZ-effective diarrhea after UCBT.

A Complete Histologic Approach to Gastrointestinal Biopsy From Hematopoietic Stem Cell Transplant Patients With Evidence of Transplant-Associated Gastrointestinal Thrombotic Microangiopathy

CONTEXT

- Transplant-associated thrombotic microangiopathy is a serious complication of hematopoietic stem cell transplant that may progress to multi-organ dysfunction. Transplant-associated thrombotic microangiopathy may involve the intestinal vasculature (intestinal transplant-associated thrombotic microangiopathy [iTMA]), causing patients to experience debilitating symptoms of ischemic colitis, including disproportionately severe abdominal pain and gastrointestinal bleeding, requiring heavy narcotic use and frequent transfusion support. Pathophysiology remains poorly investigated but may include endothelial damage mediated by inflammatory markers and the complement system. Endoscopy of hematopoietic stem cell transplant patients often produces biopsy samples, in which mucosal lamina propria capillaries are sufficient for an evaluation of iTMA features.

OBJECTIVE

- To provide a detailed review of histologic features of iTMA.

DATA SOURCES

- We conducted a systematic review of studies assessing histologic features of iTMA. Studies were identified by PubMed search and included a cohort study performed by our group.

CONCLUSIONS

- The histologic hallmark of iTMA is endothelial cell injury that leads to hemorrhage and thrombosis of the capillaries. Histologic features include endothelial cell swelling, endothelial cell separation, perivascular mucosal hemorrhage, intraluminal schistocytes, intraluminal fibrin, intraluminal microthrombi, loss of glands, and total denudation of mucosa. Identification of features consistent with iTMA has immediate implications for clinical management that could potentially improve outcome and survival.

Histologic Features of Intestinal Thrombotic Microangiopathy in Pediatric and Young Adult Patients after Hematopoietic Stem Cell Transplantation

High-risk transplantation-associated thrombotic microangiopathy (TMA) can present with multisystem involvement and is associated with a poor outcome after hematopoietic stem cell transplantation (HSCT), with < 20% 1-year survival. TMA may involve the intestinal vasculature and can present with bleeding and ischemic colitis. There are no established pathologic criteria for the diagnosis of intestinal TMA (iTMA). The goal of our study was to identify histologic features of iTMA and describe associated clinical features. We evaluated endoscopic samples from 50 consecutive HSCT patients for 8 histopathologic signs of iTMA and compared findings in 3 clinical groups based on the presence or absence of systemic high-risk TMA (hrTMA) and the presence or absence of clinically staged intestinal graft-versus-host disease (iGVHD): TMA/iGVHD, no TMA/iGVHD, and no TMA/no iGVHD. Thirty percent of the study subjects had a clinical diagnosis of systemic hrTMA. On histology, loss of glands, intraluminal schistocytes, intraluminal fibrin, intraluminal microthrombi, endothelial cell separation, and total denudation of mucosa were significantly more common in the hrTMA group (P < .05). Intravascular thrombi were seen exclusively in patients with hrTMA. Mucosal hemorrhages and endothelial cell swelling were more common in hrTMA patients but this difference did not reach statistical significance. Patients with hrTMA were more likely to experience significant abdominal pain and gastrointestinal bleeding requiring multiple blood transfusions (P < .05). Our study shows that HSCT patients with systemic hrTMA can have significant bowel vascular injury that can be identified using defined histologic criteria. Recognition of these histologic signs in post-transplantation patients with significant gastrointestinal symptoms may guide clinical decisions.

The Far Side of Vascular Injury

Substances historically thought to cause direct vascular injury in laboratory animals are a heterogeneous group of toxic agents with varied mechanisms of action. Morphologically, the reviewed agents can be broadly categorized into those targeting endothelial cell (ECs) and those targeting smooth muscle cells (SMCs). Anticancer drugs, immunosuppressants, and heavy metals are targeting primarily ECs while allylamine, β-aminopropionitrile, and mitogen-activated protein kinase kinase inhibitors affect mainly SMCs. It is now recognized that the pathogenicity of some of these agents is often mediated through intermediary events, particularly vasoconstriction. There are clear similarities in the clinical and microscopic findings associated with many of these agents in animals and man, allowing the use of animal models to investigate mechanisms and pathogenesis. The molecular pathogenic mechanisms and comparative morphology in animals and humans will be reviewed.

A new paradigm: Diagnosis and management of HSCT-associated thrombotic microangiopathy as multi-system endothelial injury

Hematopoietic stem cell transplantation (HSCT)-associated thrombotic microangiopathy (TA-TMA) is now a well-recognized and potentially severe complication of HSCT that carries a high risk of death. In those who survive, TA-TMA may be associated with long-term morbidity and chronic organ injury. Recently, there have been new insights into the incidence, pathophysiology, and management of TA-TMA. Specifically, TA-TMA can manifest as a multi-system disease occurring after various triggers of small vessel endothelial injury, leading to subsequent tissue damage in different organs. While the kidney is most commonly affected, TA-TMA involving organs such as the lung, bowel, heart, and brain is now known to have specific clinical presentations. We now review the most up-to-date research on TA-TMA, focusing on the pathogenesis of endothelial injury, the diagnosis of TA-TMA affecting the kidney and other organs, and new clinical approaches to the management of this complication after HSCT.

Fragmented Red Cell as a Possible Favorable Prognostic Marker of Hematopoietic Stem Cell Transplantation Associated Thrombotic Microangiopathy

BACKGROUND

Fragmented red cell (FRC) by automated hematologic analyzer is known to detect schistocyte. In this study, it is noted that FRC might be a favorable prognostic marker of hematopoietic stem cell transplantation associated thrombotic microangiopathy (TA-TMA).

METHODS

The peripheral blood samples and clinical data of 89 patients were collected. The diagnosis of TA-TMA was defined by the Blood and Marrow Transplant Clinical Trials Network's criteria and schistocyte or both schistocyte- and FRC-positive cases and other parameters fulfilled are regarded as TA-TMA.

RESULTS

Schistocyte and FRC displayed a correlation coefficient of 0.461 (P < 0.001) by Spearman's method. The diagnostic concordance of TA-TMA using schistocyte and FRC was 92.1% with kappa index of 0.531 (P < 0.001). The number of diagnosed patients and mean survival month were as follows: TA-TMA by schistocyte, 8 (8.9%), 13.5 month; TA-TMA by schistocyte and FRC, 7 (7.8%), 40.4 month; No TMA, 74 (83.1%), 38.3 month, respectively. Kaplan-Meier survival analysis by log-rank method of the patient with TA-TMA by schistocyte and rest of the group showed statistical significance (P < 0.01).

CONCLUSION

As evidenced by the data, FRC might be a favorable prognostic marker for TA-TMA, but additional studies with larger patients groups are required for validation of clinical applications.

Nonclinical Safety Biomarkers of Drug-induced Vascular Injury

Better biomarkers are needed to identify, characterize, and/or monitor drug-induced vascular injury (DIVI) in nonclinical species and patients. The Predictive Safety Testing Consortium (PSTC), a precompetitive collaboration of pharmaceutical companies and the U.S. Food and Drug Administration (FDA), formed the Vascular Injury Working Group (VIWG) to develop and qualify translatable biomarkers of DIVI. The VIWG focused its research on acute DIVI because early detection for clinical and nonclinical safety monitoring is desirable. The VIWG developed a strategy based on the premise that biomarkers of DIVI in rat would be translatable to humans due to the morphologic similarity of vascular injury between species regardless of mechanism. The histomorphologic lexicon for DIVI in rat defines degenerative and adaptive findings of the vascular endothelium and smooth muscles, and characterizes inflammatory components. We describe the mechanisms of these changes and their associations with candidate biomarkers for which advanced analytical method validation was completed. Further development is recommended for circulating microRNAs, endothelial microparticles, and imaging techniques. Recommendations for sample collection and processing, analytical methods, and confirmation of target localization using immunohistochemistry and in situ hybridization are described. The methods described are anticipated to aid in the identification and qualification of translational biomarkers for DIVI.

Translation Strategy for the Qualification of Drug-induced Vascular Injury Biomarkers

Drug-induced vascular injury (DIVI) is a common preclinical toxicity usually characterized by hemorrhage, vascular endothelial and smooth muscle damage, and inflammation. DIVI findings can cause delays or termination of drug candidates due to low safety margins. The situation is complicated by the absence of sensitive, noninvasive biomarkers for monitoring vascular injury and the uncertain relevance to humans. The Safer And Faster Evidence-based Translation (SAFE-T) consortium is a public–private partnership funded within the European Commission’s Innovative Medicines Initiative (IMI) aiming to accelerate drug development by qualifying biomarkers for drug-induced organ injuries, including DIVI. The group is using patients with vascular diseases that have key histomorphologic features (endothelial damage, smooth muscle damage, and inflammation) in common with those observed in DIVI, and has selected candidate biomarkers associated with these features. Studied populations include healthy volunteers, patients with spontaneous vasculitides and other vascular disorders. Initial results from studies with healthy volunteers and patients with vasculitides show that a panel of biomarkers can successfully discriminate the population groups. The SAFE-T group plans to seek endorsement from health authorities (European Medicines Agency and Food and Drug Administration) to qualify the biomarkers for use in regulatory decision-making processes.

Extra-renal manifestations of complement-mediated thrombotic microangiopathies

Thrombotic microangiopathies (TMA) are rare but severe disorders, characterized by endothelial cell activation and thrombus formation leading to hemolytic anemia, thrombocytopenia, and organ failure. Complement over activation in combination with defects in its regulation is described in an increasing number of TMA and if primary for the disease denominated as atypical hemolytic-uremic syndrome. Although TMA predominantly affects the renal microvasculature, extra-renal manifestations are observed in 20% of patients including involvement of the central nerve system, cardiovascular system, lungs, skin, skeletal muscle, and gastrointestinal tract. Prompt diagnosis and treatment initiation are therefore crucial for the prognosis of disease acute phase and the long-term outcome. This review summarizes the available evidence on extra-renal TMA manifestations and discusses the role of acute and chronic complement activation by highlighting its complex interaction with inflammation, coagulation, and endothelial homeostasis.

Diagnosis of intestinal graft-versus-host disease and thrombotic microangiopathy after allogeneic stem cell transplantation

Severe diarrhea is a serious complication after allogeneic hematopoietic stem cell transplantation (HSCT). Acute graft-versus-host disease (GVHD) has been one of the major causes of diarrhea after HSCT, which is triggered by donor-derived cytotoxic T-lymphocytes. On the other hand, intestinal thrombotic microangiopathy (TMA) sometimes coexists with acute GVHD, and intensified immunosuppression to treat acute GVHD could exacerbate intestinal TMA, presumably through the vascular endothelial cell damage. The differential diagnosis between intestinal TMA and acute GVHD of the gut has mainly relied on the pathological findings, as clinical diagnosis of intestinal TMA has not been established. Therefore, we aimed to assess the feasibility of our clinical diagnosis for the patients with diarrhea after HSCT. We made tentative clinical criteria for intestinal TMA and acute GVHD of the gut, based on the clinical manifestations, laboratory data and colonoscopic findings, and started treatment before pathological diagnosis were made. Subsequently, a pathologist retrospectively assessed the accuracy of clinical diagnosis in a blind manner. In this study, we enrolled 19 patients complicating watery diarrhea after HSCT, and diagnosed as having acute GVHD (n = 10), intestinal TMA (n = 3), or both (n = 6) according to our criteria. We demonstrated that our clinical diagnosis for intestinal TMA and acute GVHD of the gut was overall correct, in terms of the response to the therapy and the pathological diagnosis. The present study may provide a clue on making clinical diagnosis of patients with watery diarrhea after HSCT, which enables us to start a prompt therapy.

Systemic lupus erythematosus complicated with acute myocardial infarction and ischemic colitis

Acute myocardial infarction (AMI) is one of the most severe manifestations in patients with systemic lupus erythematosus (SLE). Ischemic colitis, mainly caused by intestinal vasculitis, is also one of the most serious, but uncommon, complications in SLE patients. "SLE vasculitis" simultaneously involving cardiac and gastrointestinal vessels has yet to be reported. This is the first report of SLE accompanying AMI, ischemic colitis and perforation of the digestive tract possibly due to SLE vasculitis, which was dramatically improved by treatment with high-dose glucocorticoid.

Clinicopathological manifestations and treatment of intestinal transplant-associated microangiopathy

Intestinal transplant-associated microangiopathy (i-TAM) is an important complication after allogeneic hematopoietic SCT. From 1997 to 2006, 87 of 886 patients with diarrhea after transplantation received colonoscopic biopsy. i-TAM, GVHD and CMV colitis were diagnosed histopathologically. The median duration from transplantation to the onset of diarrhea was 32 days (range: 9-130 days) and that from the onset of diarrhea to biopsy was 12 days (range: 0-74 days). The median maximal amount of diarrhea was 2 l/day (range: 130-5600 ml/day). Histopathological diagnosis included i-TAM (n=80), GVHD (n=26), CMV colitis (n=17) and nonspecific findings (n=2) with overlapping. Among 80 patients with i-TAM, abdominal pain was a major symptom, and only 11 patients fulfilled the proposed criteria for systemic TAM. Non-relapse mortality (NRM) among patients without resolution of diarrhea was 72% and i-TAM comprised 57% of NRM. NRM was 25% among patients without intensified immunosuppression, but was 52, 79 and 100% among those with intensified immunosuppression before diarrhea, after diarrhea, and before and after diarrhea, respectively. In conclusion, i-TAM is a major complication presenting massive refractory diarrhea and abdominal pain, which causes NRM. Avoiding intensified immunosuppression that damages vascular endothelium until the resolution of i-TAM may improve transplant outcome.