Biochemical mechanisms of cyclosporine neurotoxicity

Niclosamide modulates cyclosporin A-induced hepatotoxicity in a mouse model: PPAR-γ and Wnt/β-catenin crosstalk

OBJECTIVES

The aim of this study was to evaluate whether: 1) Wnt/β-catenin signaling is involved in cyclosporin A (CsA)-induced hepatotoxicity, and 2) knockdown of this pathway by niclosamide (NCL) attenuate CsA-induced hepatotoxicity.

METHODS

The experiment was accomplished in 21 days. Adult male mice were randomly distributed into five groups: control group, CsA (25 mg/kg/day) group, CsA + NCL (2.5 mg/kg/day) group, CsA + NCL (5 mg/kg/day) group, and NCL (5 mg/kg/day) group.

RESULTS

NCL showed marked hepatoprotection by significantly decreasing liver enzymes activities and ameliorating the histopathological alterations induced by CsA. Besides, NCL alleviated oxidative stress and inflammation. NCL-treated groups (2.5 and 5 mg/kg) displayed rise in the expression of hepatic peroxisome proliferator-activated receptor-γ (PPAR-γ) by 2.1- and 2.5-fold, respectively. Notably, NCL (2.5 and 5 mg/kg) significantly inhibited Wnt/β-catenin signaling, evidenced by a marked decrease in the hepatic expression of Wnt3a by 54 % and 50 %, frizzled-7 receptor by 50 % and 50 %, β-catenin by 22 % and 49 %, and c-myc by 50 % and 50 %, respectively.

CONCLUSIONS

NCL can be regarded as a potential agent to mitigate CsA-induced hepatotoxicity.

Einfluss von Medikamenten auf das EEG: Eine Übersicht

Eine Vielzahl von Präparaten mit Einfluss auf das zentrale Nervensystem, insbesondere Medikamente, die zur Standard-Therapie auf neurologischen Intensiv- und Überwachungsstationen gehören, haben einen Einfluss auf den elektroenzephalograhischen (EEG) Befund. Diese Effekte reichen von geringen Einflüssen auf Grundrhythmus und EEG-Amplituden bis zur Auslösung von epileptiformer Aktivität und Anfallsmustern. Kenntnisse über die zu erwartenden Veränderungen sind daher relevant, um neben krankheitsassoziierten Auffälligkeiten im Rahmen der Differentialdiagnostik auch medikamentöse Ursachen bedenken zu können und etwaige therapeutische Konsequenzen einzuleiten. In dem vorliegenden Übersichtartikel werden neben Einflüssen von Analgosedierung und antikonvulsiven Medikamenten auch Effekte von Neuroleptika, Antidepressiva, Immunsuppressiva sowie Antibiotika auf das EEG diskutiert.

Drug-Induced Seizures: Considerations for Underlying Molecular Mechanisms

A broad spectrum of chemical entities have been associated with drug-induced seizure (DIS), emphasizing the importance of this potential liability across various drug classes (e.g., antidepressants, antipsychotics, antibiotics, and analgesics among others). Despite its importance within drug safety testing, an understanding of the molecular mechanisms associated with DIS is often lacking. The etiology of DIS is understood to be a result of either a deficit in inhibitory (e.g., gamma aminobutyric acid) or an elevated excitatory (e.g., glutamate) signaling, leading to synchronous neuronal depolarization affecting various brain regions and impairing normal neurological functions. How this altered neuronal signaling occurs and how these changes interact with other non-brain receptor driven DIS-associated changes such as metabolic disturbances, electrolyte imbalances, altered drug metabolism, and withdrawal effects are poorly understood. Herein, we discuss important molecular mechanisms identified in DIS for several drugs and/or drug classes. With a better understanding of the molecular mechanisms associated with DIS, in vivo or in vitro models may be applied to characterize and mitigate DIS risk during drug development. Susceptibility stratification for DIS presents species differences in the following order beagle dogs > rodents and cynomolgus monkeys > Göttingen minipigs with a more than 2-fold difference between canines and minipigs, which is important to consider during non-clinical species selection. While clinical signs such as myoclonus, severe muscle jerks, or convulsions are often associated with abnormal epileptiform EEG activity, tremors are most of the time physiological and rarely observed with concurrent epileptiform EEG activity which need to be considered during DIS risk evaluation.

Circular RNAs in the Regulation of Oxidative Stress

Oxidative stress caused by an imbalance between the production and elimination of reactive metabolites and free radicals can lead to the development of a variety of diseases. Over the past years, with the development of science and technology, circular RNA (circRNA) has been found to be closely associated with oxidative stress, which plays an important role in the process of oxidative stress. Currently, the understanding of circRNAs in the mechanism of oxidative stress is limited. In this review, we described the relationship between oxidative stress and circRNAs, the circRNAs related to oxidative stress, and the role of circRNAs in promoting or inhibiting the occurrence and development of diseases associated with the oxidative stress system.

An Approach to Neurological Disorders in a Kidney Transplant Recipient

Kidney transplantation is the preferred treatment modality in patients with ESKD. However, there are associated complications that arise from immunosuppressive medications, infections, and associated comorbidities. Neurologic disorders frequently develop in patients who have received a kidney transplant, which in turn increases the associated morbidity and mortality. This review discusses the common neurologic disorders after kidney transplantation, including infections, cognitive decline, drug-related conditions, malignancy, seizure, and other neurologic complications.

Brain function and metabolism in patients with long-term tacrolimus therapy after kidney transplantation in comparison to patients after liver transplantation

Background

About 50% of the patients 5–7 years after kidney transplantation show impairment of memory, attention and executive function. Tacrolimus frequently induces neurological complications in the first few weeks after transplantation. Furthermore, tacrolimus treatment is associated with impaired cognitive function in the long-term in patients after liver transplantation. We hypothesize that long-term tacrolimus therapy is associated with cognitive dysfunction and alterations of brain structure and metabolism in patients after kidney transplantation.

Methods

Twenty-one patients 10 years after kidney transplantation underwent cognitive testing, magnetic resonance imaging and whole brain 31-phosphor magnetic resonance spectroscopy for the assessment of brain function, structure and energy metabolism. Using a cross-sectional study design the results were compared to those of patients 1 (n = 11) and 5 years (n = 10) after kidney transplantation, and healthy controls (n = 17). To further analyze the share of transplantation, tacrolimus therapy and kidney dysfunction on the results patients after liver transplantation (n = 9) were selected as a patient control group.

Results

Patients 1 and 10 years after kidney transplantation (p = 0.02) similar to patients 10 years after liver transplantation (p<0.01) showed significantly worse cognitive function than healthy controls. In contrast to patients after liver transplantation patients after kidney transplantation showed significantly reduced adenosine triphosphate levels in the brain compared to healthy controls (p≤0.01). Patients 1 and 5 years after kidney transplantation had significantly increased periventricular hyperintensities compared to healthy controls (p<0.05).

Conclusions

Our data indicate that cognitive impairment in the long-term after liver and kidney transplantation cannot exclusively be explained by CNI neurotoxicity.

Calcineurin signaling as a target for the treatment of alcohol abuse and neuroinflammatory disorders

Converging lines of evidence point to a significant role of neuroinflammation in a host of psychiatric conditions, including alcohol use disorder, TBI, and PTSD. A complex interaction of both peripheral and central signaling underlies processes involved in neuroinflammation. Calcineurin is a molecule that sits at the nexus of these processes and has been clearly linked to a number of psychiatric disorders including alcohol use disorder (AUD). Like its role in regulating peripheral immune cells, calcineurin (CN) plays an integral role in processes regulating neuroimmune function and neuroinflammatory processes. Targeting CN or elements of its signaling pathways at critical points may aid in the functional recovery from neuroinflammatory related disorders. In this review we will highlight the role of neuroinflammation and calcineurin signaling in AUD, TBI and stress-induced disorders and discuss recent findings demonstrating a therapeutic effect of immunosuppressant-induced calcineurin inhibition in a pre-clinical model of binge alcohol drinking.

Hurdles to Cardioprotection in the Critically Ill

Cardiovascular disease is the largest contributor to worldwide mortality, and the deleterious impact of heart failure (HF) is projected to grow exponentially in the future. As heart transplantation (HTx) is the only effective treatment for end-stage HF, development of mechanical circulatory support (MCS) technology has unveiled additional therapeutic options for refractory cardiac disease. Unfortunately, despite both MCS and HTx being quintessential treatments for significant cardiac impairment, associated morbidity and mortality remain high. MCS technology continues to evolve, but is associated with numerous disturbances to cardiac function (e.g., oxidative damage, arrhythmias). Following MCS intervention, HTx is frequently the destination option for survival of critically ill cardiac patients. While effective, donor hearts are scarce, thus limiting HTx to few qualifying patients, and HTx remains correlated with substantial post-HTx complications. While MCS and HTx are vital to survival of critically ill cardiac patients, cardioprotective strategies to improve outcomes from these treatments are highly desirable. Accordingly, this review summarizes the current status of MCS and HTx in the clinic, and the associated cardiac complications inherent to these treatments. Furthermore, we detail current research being undertaken to improve cardiac outcomes following MCS/HTx, and important considerations for reducing the significant morbidity and mortality associated with these necessary treatment strategies.

Recent Topics on The Mechanisms of Immunosuppressive Therapy-Related Neurotoxicities

Although transplantation procedures have been developed for patients with end-stage hepatic insufficiency or other diseases, allograft rejection still threatens patient health and lifespan. Over the last few decades, the emergence of immunosuppressive agents such as calcineurin inhibitors (CNIs) and mammalian target of rapamycin (mTOR) inhibitors have strikingly increased graft survival. Unfortunately, immunosuppressive agent-related neurotoxicity commonly occurs in clinical practice, with the majority of neurotoxicity cases caused by CNIs. The possible mechanisms through which CNIs cause neurotoxicity include increasing the permeability or injury of the blood–brain barrier, alterations of mitochondrial function, and alterations in the electrophysiological state. Other immunosuppressants can also induce neuropsychiatric complications. For example, mTOR inhibitors induce seizures, mycophenolate mofetil induces depression and headaches, methotrexate affects the central nervous system, the mouse monoclonal immunoglobulin G2 antibody (used against the cluster of differentiation 3) also induces headaches, and patients using corticosteroids usually experience cognitive alteration. Therapeutic drug monitoring, individual therapy based on pharmacogenetics, and early recognition of symptoms help reduce neurotoxic events considerably. Once neurotoxicity occurs, a reduction in the drug dosage, switching to other immunosuppressants, combination therapy with drugs used to treat the neuropsychiatric manifestation, or blood purification therapy have proven to be effective against neurotoxicity. In this review, we summarize recent topics on the mechanisms of immunosuppressive drug-related neurotoxicity. In addition, information about the neuroprotective effects of several immunosuppressants is also discussed.

Cyclosporin a Potentiates the Cytotoxic Effects of Methyl Methanesulphonate in HL-60 and K562 Cells

Methyl methanesulphonate (MMS) is a DNA damaging agent, which induces oxidative stress, ATP depletion, and consequently, cell death, in HL-60 and K562 cells. The cell death induced by MMS predominantly exhibited the morphological and biochemical hallmarks of necrosis. A minor population of dying cells exhibited apoptotic hallmarks, especially in K562 cell cultures. Cyclosporin A (CsA) was used to modulate the MMS-induced cell death. Our results indicated that CsA did not prevent cells from dying, but changed the mode of death from necrotic to apoptotic. Surprisingly, CsA enhanced oxidative stress and increased the overall number of dead cells. Based on these results, we conclude that the modulatory effect of CsA on MMS-induced cell death might arise from an interference by CsA with mitochondrial metabolism, rather than from inhibition of the MMS efflux mediated by P-glycoprotein.

Cyclosporin A ameliorates cerebral oxidative metabolism and infarct size in the endothelin-1 rat model of transient cerebral ischaemia

Cerebral microdialysis can be used to detect mitochondrial dysfunction, a potential target of neuroprotective treatment. Cyclosporin A (CsA) is a mitochondrial stabiliser that in a recent clinical stroke trial showed protective potential in patients with successful recanalisation. To investigate specific metabolic effects of CsA during reperfusion, and hypothesising that microdialysis values can be used as a proxy outcome measure, we assessed the temporal patterns of cerebral energy substrates related to oxidative metabolism in a model of transient focal ischaemia. Transient ischaemia was induced by intracerebral microinjection of endothelin-1 (150 pmol/15 µL) through stereotaxically implanted guide cannulas in awake, freely moving rats. This was immediately followed by an intravenous injection of CsA (NeuroSTAT; 15 mg/kg) or placebo solution during continuous microdialysis monitoring. After reperfusion, the lactate/pyruvate ratio (LPR) was significantly lower in the CsA group vs placebo (n = 17, 60.6 ± 24.3%, p = 0.013). Total and striatal infarct volumes (mm³) were reduced in the treatment group (n = 31, 61.8 ± 6.0 vs 80.6 ± 6.7, p = 0.047 and 29.9 ± 3.5 vs 41.5 ± 3.9, p = 0.033). CsA treatment thus ameliorated cerebral reperfusion metabolism and infarct size. Cerebral microdialysis may be useful in evaluating putative neuroprotectants in ischaemic stroke.

Microglial Calcium Release-Activated Calcium Channel Inhibition Improves Outcome from Experimental Traumatic Brain Injury and Microglia-Induced Neuronal Death

Store-operated Ca²⁺ entry (SOCE) mediated by calcium release-activated calcium (CRAC) channels contributes to calcium signaling. The resulting intracellular calcium increases activate calcineurin, which in turn activates immune transcription factor nuclear factor of activated T cells (NFAT). Microglia contain CRAC channels, but little is known whether these channels play a role in acute brain insults. We studied a novel CRAC channel inhibitor to explore the therapeutic potential of this compound in microglia-mediated injury. Cultured microglial BV2 cells were activated by Toll-like receptor agonists or IFNγ. Some cultures were treated with a novel CRAC channel inhibitor (CM-EX-137). Western blots revealed the presence of CRAC channel proteins STIM1 and Orai1 in BV2 cells. CM-EX-137 decreased nitric oxide (NO) release and inducible nitric oxide synthase (iNOS) expression in activated microglia and reduced agonist-induced intracellular calcium accumulation in microglia, while suppressing inflammatory transcription factors nuclear factor kappa B (NF-κB) and nuclear factor of activated T cells (NFAT). Male C57/BL6 mice exposed to experimental brain trauma and treated with CM-EX-137 had decreased lesion size, brain hemorrhage, and improved neurological deficits with decreased microglial activation, iNOS and Orai1 and STIM1 levels. We suggest a novel anti-inflammatory approach for managing acute brain injury. Our observations also shed light on new calcium signaling pathways not described previously in brain injury models.

Liver transplantation during infancy: No increased rate of neurological complications

pLT is a highly standardized therapy for children with end-stage liver disease and liver-based metabolic diseases. However, NCs after transplantation occur and especially younger children are considered as more vulnerable and susceptible to NCs. Up to now, detailed data particularly for the very young age group do not exist. We therefore retrospectively studied NCs in children after pLT under age of 24 months. Forty children aged between 19 days and 22 months were evaluated according to type of NC and potential risk factors. NCs occurred in 8/40 patients (20%). All experienced new-onset seizures and in 1/6 surviving patients, seizures evolved into epilepsy. Other NCs were intracerebral abscess (1/8 patients) and subdural hemorrhage (1/8 patients). The overall 3-year mortality rate was 10% (4/40 patients). Significant risk factors for NCs and therefore seizures were HAT (P = 0.020), total surgery time (P = 0.009), retransplantation (P < 0.001), period of catecholamine therapy (P = 0.024), period of mechanical ventilation (P = 0.014), and period of sedation (P = 0.010). Our study is the first to provide detailed information on NCs after pLT in children under 24 months of age. The incidence of NCs in this particular group of very young patients was not increased compared to previously published data of children of all ages. Main NC was new-onset seizure. In the surviving infants, prognosis of seizure was excellent and the risk of developing epilepsy was low. Even more, the occurrence of NCs did not significantly affect mortality or survival in this particular age group.

Granulomonocytapheresis as a cell-dependent treatment option for patients with inflammatory bowel disease: Concepts and clinical features for better therapeutic outcomes

Ulcerative colitis (UC) and Crohn's disease (CD) are major phenotypes of the chronic inflammatory bowel disease (IBD), which afflicts millions of individuals throughout the world with debilitating symptoms. The chronic nature of IBD means that patients require life-long medications, and this may lead to drug dependency, loss of response together with adverse side effects as additional morbidity factors. The efficacy of antitumour necrosis factor (TNF)-α biologics has validated the role of inflammatory cytokines notably TNF-α in the exacerbation and perpetuation of IBD. However, cytokines are released by myeloid lineage leucocytes like the CD14⁺ CD16⁺ monocyte phenotype. Additionally in IBD, myeloid leucocytes are elevated with activation behavior, while lymphocytes are compromised. Therefore, patients' leucocytes appear logical targets of therapy. Adsorptive granulomonocytapheresis (GMA) with an Adacolumn uses carriers, which interact with the Fcγ receptor expressing leucocytes and deplete the elevated myeloid leucocytes, while the neutrophils, which re-enter the circulation via the Adacolumn outflow (≥40%) are phagocytosed by CD19 B-cells to become interleukin (IL)-10 producing Bregs or CD19^high CD1D^high B-cells. IL-10 is an anti-inflammatory cytokine. GMA has been applied to treat patients with IBD. The efficacy outcomes have been impressive as well as disappointing, the clinical response to GMA defines the patients' disease course and severity at entry. Efficacy outcomes in patients with deep ulcers together with extensive loss of the mucosal tissue are not encouraging, while patients without these features respond well and attain a favorable long-term disease course. Accordingly, for responder patients, GMA fulfills a desire to be treated without drugs.

Applications and limitations of behaviorally conditioned immunopharmacological responses

The importance of placebo responses for the treatment of various medical conditions has increasingly been recognized, whereas knowledge and systematic application in clinical settings are still sparse. One possible application for placebo responses in pharmacotherapy is given by learning paradigms, such as behaviorally conditioned immunosuppression, aiming at drug dose reduction while maintaining therapeutic efficacy of drug treatment. In an established learning paradigm of conditioned taste aversion/avoidance (CTA) in both, rats and humans, respectively, a novel-tasting drinking solution (conditioned stimulus, CS) is paired with an injection of the immunosuppressive drug cyclosporine A (CsA) as unconditioned stimulus (US). The conditioned response, evoked by re-presenting the CS alone at a later time, is reflected by avoidance behavior of consuming the solution (conditioned taste aversion; CTA) and a diminished interleukin (IL)-2 and interferon (IFN)-γ cytokine production as well as mRNA expression of rat splenic T cells or human peripheral T lymphocytes, closely mimicking the immunosuppressive effects of CsA. However, due to unreinforced CS-re-exposure conditioned responses progressively decreases over time (extinction), reflecting a considerable challenge for potential clinical applications of this learned immunosuppression. The present article discusses and critically reviews actual approaches, applications but also limitations of learning paradigms in immune pharmacotherapy.

Posterior reversible encephalopathy in the intensive care unit

Posterior reversible encephalopathy syndrome (PRES) is increasingly diagnosed in the emergency department, and medical and surgical intensive care units. PRES is characterized by acute onset of neurologic symptoms in the setting of blood pressure fluctuations, eclampsia, autoimmune disease, transplantation, renal failure, or exposure to immunosuppressive or cytotoxic drugs, triggers known to admit patients to the intensive care unit (ICU). Although the exact pathophysiology remains unknown, there is growing consensus that PRES results from endothelial dysfunction. Because of the heterogeneous nature of the disorder, it is probable that different mechanisms of endothelial injury are etiologically important in different clinical situations. The presence of bilateral vasogenic edema on brain imaging, particularly in parieto-occipital regions, is of great diagnostic utility but PRES remains a clinical diagnosis. Although largely reversible, PRES can result in irreversible neurologic injury and even death. The range of clinical and radiographic manifestations of the syndrome is probably broader than previously thought, and it is imperative that clinicians become familiar with the full spectrum of the disorder, as prompt recognition and elimination of an inciting factor improve outcome. PRES may be the most frequent toxic-metabolic encephalopathy seen in the ICU.

Oxidative Stress and Liver Morphology in Experimental Cyclosporine A-Induced Hepatotoxicity

Cyclosporine A is an immunosuppressive drug used after organ's transplantation. The adverse effects on such organs as kidney or liver may limit its use. Oxidative stress is proposed as one of the mechanisms of organs injury. The study was designed to elucidate CsA-induced changes in liver function, morphology, oxidative stress parameters, and mitochondria in rat's hepatocytes. Male Wistar rats were used: group A (control) receiving physiological saline, group B cyclosporine A in a dose of 15 mg/kg/day subcutaneously, and group C the CsA-vehicle (olive oil). On the 28th day rats were anesthetized. The following biochemical changes were observed in CsA-treated animals: increased levels of ALT, AST, and bilirubin in the serum, statistically significant changes in oxidative stress parameters, and lipid peroxidation products in the liver supernatants: MDA+4HAE, GSH, GSSG, caspase 3 activity, and ADP/ATP, NAD(+)/NADH, and NADP(+)/NADPH ratios. Microscopy of the liver revealed congestion, sinusoidal dilatation, and focal hepatocytes necrosis with mononuclear cell infiltration. Electron microscope revealed marked mitochondrial damage. Biochemical studies indicated that CsA treatment impairs liver function and triggers oxidative stress and redox imbalance in rats hepatocytes. Changes of oxidative stress markers parallel with mitochondrial damage suggest that these mechanisms play a crucial role in the course of CsA hepatotoxicity.

Posterior Reversible Encephalopathy Syndrome After Transplantation: a Review

Posterior reversible encephalopathy syndrome (PRES) is a rare neurological disease. Recently, an increase in the number of transplantations has led to more cases being associated with PRES than what was previously reported. Calcineurin inhibitors (CNIs) are major risk factors for PRES in posttransplantation patients. The mechanisms of the development of PRES remain to be unclear. The typical clinical symptoms of PRES include seizures, acute encephalopathy syndrome, and visual symptoms. The hyperintense signal on fluid-attenuated inversion recovery image is the characteristic of the imaging appearance in these patients. In addition, other abnormal signals distributed in multiple locations are also reported in some atypical cases. Unfortunately, PRES is often not recognized or diagnosed too late due to complicated differential diagnoses, such as ischemic stroke, progressive multifocal leukoencephalopathy, and neurodegenerative diseases. Thus, this review emphasizes the importance of considering the possibility of PRES when neurological disturbances appear after solid organ transplantation or hematopoietic cell transplantation. Moreover, this review demonstrates the molecular mechanisms of PRES associated with CNIs after transplantation, which aims to help clinicians further understand PRES in the transplantation era.

Age-dependent vulnerability of cyclosporine-associated encephalopathy in children

INTRODUCTION

Cyclosporine (CsA) is an immunosuppressant known for its neurotoxicity, which presents with acute encephalopathy and seizures in the most severe form. However, whether there is age-related neurological susceptibility in pediatric population is poorly defined. The study aims to examine the vulnerability of CsA neurotoxicity among different age groups of pediatric patients in terms of occurrence rate, acute presentations, long-term outcomes, and neuroimaging findings.

METHODS

Pediatric patients (age <18 years) who received CsA in a tertiary referral center between July 1, 1988 and August 31, 2011 were retrospectively reviewed for CsA-related encephalopathy. The clinical presentations, demographic data, and laboratory examinations were analyzed through t-test for numerical and Fisher's exact test for categorical variables. Exact logistic regression was used to examine the effect of each variables.

RESULTS

Twelve (8%) of the enrolled 146 patients developed CsA-induced encephalopathy. Compared to the non-neurotoxicity group, the neurotoxicity group was significantly younger upon starting CsA (p = 0.008) and had higher percentages of hypertension after CsA treatment (p = 0.01). Regression analysis showed that age <6 years (OR 7.6, 95% CI 1.6-51.5; p = 0.007) and hypertension after CsA (OR 6.3, 95% CI 1.4-35.4; p = 0.016) were significantly associated with CsA encephalopathy. Younger children were prone to have more severe seizures in the acute stage and more epilepsy and neuropsychiatric disorders in the future. Follow-up neuroimaging showed parietal cerebral atrophy in all examined children <6 years of age.

CONCLUSIONS

Age-dependent susceptibility of CsA neurotoxicity occurs in children, with severe acute presentations and long-term sequelae in children below 6 years old.

Severe fludarabine neurotoxicity after reduced intensity conditioning regimen to allogeneic hematopoietic stem cell transplantation: a case report

We present a case of severe, irreversible neurotoxicity in a 55-year-old-patient with myelofibrosis undergoing hematopoietic stem cell transplantation following a reduced intensity conditioning including fludarabine. The patient developed progressive sensory-motor, visual and consciousness disturbances, eventually leading to death. MRI imaging pattern was unique and attributable to fludarabine neurotoxicity.

Everolimus and sirolimus in transplantation-related but different

INTRODUCTION

The inhibitors of the mammalian target of rapamycin (mTOR) sirolimus and everolimus are used not only as immunosuppressants after organ transplantation in combination with calcineurin inhibitors (CNIs) but also as proliferation signal inhibitors coated on drug-eluting stents and in cancer therapy. Notwithstanding their related chemical structures, both have distinct pharmacokinetic, pharmacodynamic and toxicodynamic properties.

AREAS COVERED

The additional hydroxyethyl group at the C(40) of the everolimus molecule results in different tissue and subcellular distribution, different affinities to active drug transporters and drug-metabolizing enzymes as well as differences in drug-target protein interactions including a much higher potency in terms of interacting with the mTOR complex 2 than sirolimus. Said mechanistic differences as well as differences found in clinical trials in transplant patients are reviewed.

EXPERT OPINION

In comparison to sirolimus, everolimus has higher bioavailability, a shorter terminal half-life, different blood metabolite patterns, the potential to antagonize the negative effects of CNIs on neuronal and kidney cell metabolism (which sirolimus enhances), the ability to stimulate mitochondrial oxidation (which sirolimus inhibits) and to reduce vascular inflammation to a greater extent. A head-to-head, randomized trial comparing the safety and tolerability of these two mTOR inhibitors in solid organ transplant recipients is merited.

Adacolumn leucocytapheresis for ulcerative colitis: clinical and endoscopic features of responders and unresponders

Cytokines such as TNF-α have a validated role in the immunopathogensis of ulcerative colitis (UC), and intercepting inflammatory cytokines is currently the best option for maximizing treatment efficacy. One of the major sources of inflammatory cytokines are myeloid linage leucocytes (granulocytes, monocytes), which are present in great numbers in the colonic tissue. Their selective depletion by adsorptive granulocyte, monocyte apheresis (GMA), should be therapeutic in patients with UC, although until now efficacy outcomes have been both encouraging and disappointing. The authors' view is that in patients with UC, there is an evolving scope for therapeutic opportunity based on taking away the sources of inflammatory cytokines, also considering the favorable safety profile of GMA.

Treating inflammatory bowel disease by adsorptive leucocytapheresis: A desire to treat without drugs

Ulcerative colitis and Crohn’s disease are the major phenotypes of the idiopathic inflammatory bowel disease (IBD), which afflicts millions of individuals throughout the world with debilitating symptoms, impairing function and quality of life. Current medications are aimed at reducing the symptoms or suppressing exacerbations. However, patients require life-long medications, and this can lead to drug dependency, loss of response together with adverse side effects. Indeed, drug side effects become additional morbidity factor in many patients on long-term medications. Nonetheless, the efficacy of anti-tumour necrosis factors (TNF)-α biologics has validated the role of inflammatory cytokines notably TNF-α in the exacerbation of IBD. However, inflammatory cytokines are released by patients’ own cellular elements including myeloid lineage leucocytes, which in patients with IBD are elevated with activation behaviour and prolonged survival. Accordingly, these leucocytes appear logical targets of therapy and can be depleted by adsorptive granulocyte/monocyte apheresis (GMA) with an Adacolumn. Based on this background, recently GMA has been applied to treat patients with IBD in Japan and in the European Union countries. Efficacy rates have been impressive as well as disappointing. In fact the clinical response to GMA seems to define the patients’ disease course, response to medications, duration of active disease, and severity at entry. The best responders have been first episode cases (up to 100%) followed by steroid naïve and patients with a short duration of active disease prior to GMA. Patients with deep ulcers together with extensive loss of the mucosal tissue and cases with a long duration of IBD refractory to existing medications are not likely to benefit from GMA. It is clinically interesting that patients who respond to GMA have a good long-term disease course by avoiding drugs including corticosteroids in the early stage of their IBD. Additionally, GMA is very much favoured by patients for its good safety profile. GMA in 21^st century reminds us of phlebotomy as a major medical practice at the time of Hippocrates. However, in patients with IBD, there is a scope for removing from the body the sources of pro-inflammatory cytokines and achieve disease remission. The bottom line is that by introducing GMA at an early stage following the onset of IBD or before patients develop extensive mucosal damage and become refractory to medications, many patients should respond to GMA and avoid pharmacologics. This should fulfill the desire to treat without drugs.

Posterior reversible encephalopathy syndrome in children with kidney disease

Posterior reversible encephalopathy syndrome (PRES) is a clinic-radiographic entity of heterogeneous etiologies that are grouped together because of similar findings on neuro-imaging and associated symptom complex of headache, vision loss, altered mentation, and seizures. Although usually considered benign and reversible, characteristics of this syndrome in pediatric patients remain obscure. This case series included 11 patients (8 males, 3 females, age 3-15 years) of PRES during September 2010 to February 2012 out of a total 660 renal pediatric patients (1.66%). We studied their clinical profile, contributory factors, and outcome. Presenting symptoms were headache in 73%, dimness of vision or cortical blindness in 36%, seizures in 91%, and altered mentation in 55%. The associated renal diseases were acute renal failure (55%), chronic renal failure (9%), and 36% had normal renal function. The contributory factors were uncontrolled hypertension (100%), severe hypoproteinemia (9%), persistent hypocalcemia (9%), hemolytic uremic syndrome (36%), cyclosporine toxicity (9%), lupus nephritis (9%), high hematocrit (9%), and pulse methylprednisolone (9%). Brain imaging showed involvement of occipito-parietal area (100%) and other brain areas (63%). All but one patient of hemolytic uremic syndrome had complete clinical neurological recovery in a week, and all had normal neurological imaging after 4-5 weeks. PRES is an underdiagnosed entity in pediatric renal disease patients. Associated hypertension, renal disease, and immunosuppressive treatment are important triggers. Early diagnosis and treatment of comorbid conditions is of prime importance for early reversal of syndrome.

The levels of pro-inflammatory factors are significantly decreased in cerebral palsy patients following an allogeneic umbilical cord blood cell transplant

BACKGROUND AND OBJECTIVES

The transplantation of human umbilical cord blood cells (hUCBCs) has been shown to attenuate the unregulated activation of microglia in a rat model of cerebral palsy (CP). To investigate whether hUCBCs transplantation is also anti-inflammatory in humans, we performed a clinical trial in patients with CP.

METHODS AND RESULTS

Allogeneic or autologous hUCBCs and erythropoietin (EPO) were intravenously injected into human patients with CP (mean age of approximately 38 weeks), and patients were analyzed for their motor function and social behavior. Blood samples were tested for cytokine levels. The most surprising finding in the study was that the cytokine levels were dependent on the donor cell source (allogeneic or autologous). Interestingly, the allogeneic treatment group demonstrated significantly decreased levels of pro-inflammatory factors, such as IL-1α, IL-6, TNF-β, and RANTES, and showed a statistically significant improvement in motor and social behavior compared to the autologous treatment group.

CONCLUSIONS

Given that inflammation plays a pivotal role in CP, our results suggest that allogeneic hUCBCs therapy may be an appropriate strategy for CP treatment. In addition, prior to transplantation, a detailed analysis of the amount of proinflammatory cytokines in cord blood may be needed to avoid exacerbating inflammatory responses.

The influence of immunosuppressive drugs on neural stem/progenitor cell fate in vitro

In allogenic and xenogenic transplantation, adequate immunosuppression plays a major role in graft survival, especially over the long term. The effect of immunosuppressive drugs on neural stem/progenitor cell fate has not been sufficiently explored. The focus of this study is to systematically investigate the effects of the following four different immunotherapeutic strategies on human neural progenitor cell survival/death, proliferation, metabolic activity, differentiation and migration in vitro: (1) cyclosporine A (CsA), a calcineurin inhibitor; (2) everolimus (RAD001), an mTOR-inhibitor; (3) mycophenolic acid (MPA, mycophenolate), an inhibitor of inosine monophosphate dehydrogenase and (4) prednisolone, a steroid. At the minimum effective concentration (MEC), we found a prominent decrease in hNPCs' proliferative capacity (BrdU incorporation), especially for CsA and MPA, and an alteration of the NAD(P)H-dependent metabolic activity. Cell death rate, neurogenesis, gliogenesis and cell migration remained mostly unaffected under these conditions for all four immunosuppressants, except for apoptotic cell death, which was significantly increased by MPA treatment.

Immunosuppressants affect human neural stem cells in vitro but not in an in vivo model of spinal cord injury

Clinical immunosuppression protocols use calcineurin inhibitors, such as cyclosporine A (CsA) or tacrolimus (FK506), or mammalian target of rapamycin (mTOR) inhibitors, such as sirolimus (rapamycin). These compounds alter immunophilin ligand signaling pathways, which are known to interact downstream with mediators for human neural stem cell (hNSC) differentiation and proliferation, suggesting that immunosuppressants may directly alter hNSC properties. We investigated whether immunosuppressants can exert direct effects on the differentiation, proliferation, survival, and migration of human central nervous system-derived stem cells propagated as neurospheres (hCNS-SCns) in vitro and in an in vivo model of spinal cord injury. We identified unique, immunosuppressant-dependent effects on hCNS-SCns differentiation and proliferation in vitro. All immunosuppressants tested increased neuronal differentiation, and CsA and rapamycin inhibited proliferation in vitro. No immunosuppressant-mediated effects on hCNS-SCns survival or migration in vitro were detected. These data suggested that immunosuppressant administration could alter hCNS-SCns properties in vivo. We tested this hypothesis by administering immunosuppressants to constitutively immunodeficient spinal cord injured mice and assessed survival, proliferation, differentiation, and migration of hCNS-SCns after 14 weeks. In parallel, we administered immunosuppressants to immunocompetent spinal cord injury (SCI) mice and also evaluated hCNS-SCns engraftment and fate. We identified no effect of immunosuppressants on the overall hCNS-SCns fate profile in either xenotransplantation model. Despite a lower level of human cell engraftment in immunocompetent SCI mice, functional locomotor recovery was observed in animals receiving hCNS-SCns transplantation with no evidence of allodynia. These data suggest that local cues in the microenvironment could exert a stronger influence on hCNS-SCns than circulating levels of immunosuppressants; however, differences between human and rodent metabolism/pharmokinetics and xenograft versus allograft paradigms could be determining factors.

Review article: the management of autoimmune hepatitis beyond consensus guidelines

BACKGROUND

Consensus guidelines aid in the diagnosis and management of autoimmune hepatitis, but they are frequently based on low-quality clinical evidence, conflicting experiences and divergent opinions. Recommendations may be weak, discrepant or non-existent at critical decision points.

AIMS

To identify the decision points where guidelines are weak or non-existent and review the evidence essential in the decision process.

METHODS

Full-text articles published in English using the keyword 'autoimmune hepatitis' were identified by PubMed from 1972 to 2013. Personal experience and investigations in autoimmune hepatitis also identified important contributions.

RESULTS

Seventy per cent of the guidelines developed by the American Association for the Study of Liver Diseases and 48% of those proposed by the British Society of Gastroenterology are based on low-quality evidence, conflicting experiences or divergent opinions. The key uncertainties in diagnosis relate to the timing of liver biopsy, recognising acute severe (fulminant) disease, interpreting coincidental nonclassical histological changes, accommodating atypical or deficient features in non-White patients, differentiating drug-induced from classical disease and identifying overlap syndromes. The key uncertainties in management relate to pre-treatment testing for thiopurine methyltransferase activity, treating asymptomatic mild disease, determining treatment end points, managing suboptimal responses, incorporating nonstandard medications as front-line and salvage agents, using azathioprine in pregnancy and instituting surveillance for hepatocellular carcinoma.

CONCLUSIONS

Consensus guidelines are fraught with uncertainties in the diagnosis and management of autoimmune hepatitis. Each decision point must counterbalance the current available evidence and tailor the application of this evidence to the individual patient.

Neurobehavioural activation during peripheral immunosuppression

Like other physiological responses, immune functions are the subject of behavioural conditioning. Conditioned immunosuppression can be induced by contingently pairing a novel taste with an injection of the immunosuppressant cyclosporine A (CsA) in an associative learning paradigm. This learned immunosuppression is centrally mediated by the insular cortex and the amygdala. However, the afferent mechanisms by which the brain detects CsA are not understood. In this study we analysed whether CsA is sensed via the chemosensitive vagus nerve or whether CsA directly acts on the brain. Our experiments revealed that a single peripheral administration of CsA increases neuronal activity in the insular cortex and the amygdala as evident from increased electric activity, c-Fos expression and amygdaloid noradrenaline release. However, this increased neuronal activity was not affected by prior vagal deafferentation but rather seems to partially be induced by direct action of CsA on cortico-amygdaloid structures and the chemosensitive brainstem regions area postrema and nucleus of the solitary tract. Together, these data indicate that CsA as an unconditioned stimulus may directly act on the brain by a still unknown transduction mechanism.

The Lived Experience of Peripheral Neuropathy after Solid Organ Transplant

Background

The immunosuppressants required after transplant cause peripheral neuropathy with an incidence of 10% to 60%. Peripheral neuropathy adversely affects health-related quality of life in other populations.

Objective

To describe the lived experience of peripheral neuropathy after solid organ transplant.

Design

A qualitative phenomenological study with semistructured interviews. A purposive sample of 7 solid organ transplant recipients with peripheral neuropathy was recruited from 2 transplant clinics at a large Midwest tertiary care center. Interviews were audio taped and transcribed verbatim. Data were analyzed line-byline and coded by using HyperResearch 2.0.

Results

Although participants' experiences were similar to those reported by others with peripheral neuropathy, there were also unique differences. Unique to this population was unexpected onset, rapid escalation of symptoms, lack of provider monitoring, and poor provider response to reported symptoms. Their experience demonstrated that peripheral neuropathy diminished health-related quality of life. Four themes emerged from the data: (1) nothing is supposed to happen after transplant; (2) neuropathy causes me more problems than my heart; (3) maybe there is something that could help; and (4) I've learned to live with certain limitations.

Conclusion

Development of or worsening of peripheral neuropathy after solid organ transplant may decrease health-related quality of life. Follow-up care should include vigilant monitoring for signs of peripheral neuropathy. Providers need to provide early treatment, education, support, empathy, and understanding.

Drug choices in autoimmune hepatitis: part B--Nonsteroids

Nonsteroidal medications, previously unfamiliar in the management of autoimmune hepatitis, can supplement or replace conventional corticosteroid regimens, especially in problematic patients. Mycophenolate mofetil is a next-generation purine antagonist that has been useful in treating patients with azathioprine intolerance. It has been less effective in salvaging patients with steroid-refractory disease. Azathioprine is the choice as a corticosteroid-sparing agent in treatment-naive patients and in individuals with corticosteroid intolerance, incomplete response and relapse after drug withdrawal. Tacrolimus is preferred over cyclosporine for recalcitrant disease because of its established preference in organ transplantation, but replacement with cyclosporine should be considered if the disease worsens on treatment. Rapamycin has antiproliferative and proapoptotic actions that warrant further study in autoimmune hepatitis. The nonstandard, nonsteroidal medications are mainly salvage therapies with off-label indications that must be used in highly individualized and well-monitored clinical situations.

Pre- and post-treatment with cyclosporine A in a rat model of transient focal cerebral ischaemia with multimodal MRI screening

BACKGROUND

Irreversible damage may occur at reperfusion after sustained cerebral ischaemia.

AIMS

We investigated the value of cyclosporine A for reducing the infarct size in a model of transient middle cerebral artery occlusion.

METHODS

Twenty-seven Sprague-Dawley rats sustained a middle cerebral artery occlusion of one-hour. Acute multimodal Magnetic Resonance Imaging (MRI) was used during occlusion to confirm the success of surgery and measure baseline lesion size. Animals were randomly treated by: (i) intracarotid cyclosporine A (10 mg/kg) 20 mins before middle cerebral artery occlusion (pretreatment group); (ii) intracarotid cyclosporine A (10 mg/kg) immediately after reperfusion (post-treatment group); and (iii) intracarotid saline immediately after reperfusion.

RESULTS

Histopathological measurements on day 1 showed a significant reduction of infarct size in the pretreatment group compared to the post-treatment (percentage values of ipsilateral hemispheres: 16 ± 5% vs. 29 ± 11%, P = 0·004) and saline groups (16 ± 5% vs. 42 ± 12%, P = 0·015). No significant difference was observed between the post-treatment and saline groups (P = 0·065). Behavioural examinations on day 1 showed no significant difference between groups. Immunohistochemistry showed a statistically significant reduction of microglial cell count in the pretreatment group compared to either saline or cyclosporine A post-treatment groups.

CONCLUSIONS

We conclude that intracarotid cyclosporine A is effective in reducing infarct size when given prior to ischaemia, but not when administered at reperfusion.

Cyclosporine-A as a neuroprotective agent against stroke: its translation from laboratory research to clinical application

Stoke remains a leading cause of death and disability with limited treatment options. Extensive research has been aimed at studying cell death events that accompany stroke and how to use these same cell death pathways as potential therapeutic targets for treating the disease. The mitochondrial permeability transition pore (MPTP) has been implicated as a major factor associated with stroke-induced neuronal cell death. MPTP activation and increased permeability has been shown to contribute to the events that lead to cell death. Cyclosporine A (CsA), a widely used immunosuppressant in transplantation and rheumatic medicine, has been recently shown to possess neuroprotective properties through its ability to block the MPTP, which in turn inhibits neuronal damage. This newfound CsA-mediated neuroprotection pathway prompted research on its use to prevent cell death in stroke and other neurological conditions. Preclinical studies are being conducted in hopes of establishing the safety and efficacy guidelines for CsA use in human trials as a potential neuroprotective agent against stroke. In this review, we provide an overview of the current laboratory and clinical status of CsA neuroprotection.

Repeated recall of learned immunosuppression: evidence from rats and men

Akin to other physiological responses, the immune system can be modified, via Pavlovian or behavioral conditioning. It is unknown, however, whether and to what extent learned immune responses can be repeatedly recalled over time. Here we demonstrate in both rats and humans that repeated contingent pairing of a novel taste (conditioned stimulus, CS) together with the immunosuppressive drug cyclosporine A as unconditioned stimulus (US) leads to the acquisition of a learned immunosuppression. Sole presentation of the CS caused a significant inhibition of interleukin (IL)-2 and interferon (IFN)-γ production by rat splenic T cells and human peripheral T lymphocytes, closely mimicking the effect of the drug. More importantly, a comparable suppression of cytokine production was also observed after a second, unreinforced exposure to the CS that was separated from the first evocation by an interval of 6 (rats) or 11 (humans)days, respectively. Together, our findings demonstrate that a learned immunosuppression can be repeatedly recalled in both animals and humans, which is an important prerequisite for the implementation of conditioning paradigms as supportive therapy.

A Review of Laboratory and Clinical Data Supporting the Safety and Efficacy of Cyclosporin A in Traumatic Brain Injury

For decades, cyclosporin A (CsA) has proved to be safe and effective for use in transplantation. In the past 10 years, this agent has shown neuroprotective effects in animal models of traumatic brain injury (TBI). This review article provides a critical overview of the literature on CsA neuroprotective effects in animal studies and current findings of clinical trials in the treatment of TBI with an emphasis on the possible CsA molecular mechanism of action. Animal data provide compelling evidence of the therapeutic benefits of CsA in TBI, but the outcome indices are heterogeneous with respect to the animal model of TBI as well as the route, dose, and timing of CsA administration. Similarly, clinical studies (phase II trials) adapting almost identical patient inclusion criteria have demonstrated the safety of CsA use in TBI, but the clinical trials are also heterogeneous based on study design, especially with regard to the variable timing of CsA administration after TBI. In view of the translational shortcomings of the preclinical studies and the rather pilot nature of the limited clinical trials that recently reached phase III, we offer guidance on the future directions of laboratory investigations on CsA that could improve the safety and efficacy of this agent in subsequent larger clinical trials.

Proton Magnetic Resonance Spectroscopy in adult cancer patients with delirium

Delirium is associated with a host of negative outcomes, including increased risk of mortality, longer hospital stay, and poor long-term cognitive function. The pathophysiology of delirium is not well understood. Cancer patients undergoing a bone marrow transplant (BMT) are at high risk for developing delirium and Proton Magnetic Resonance Spectroscopy ((1)H MRS) could lead to better understanding of the delirium process. Fourteen BMT patients and 10 controls completed (1)H MRS, positioned above the corpus callosum, shortly after delirium onset or at study end if no delirium occurred. In the BMT-delirium group, statistically significantly elevated tCho/tCr was found in contrast to the BMT-no delirium group. The BMT-delirium group also showed statistically significantly lesser NAA/tCho compared with both controls and the BMT-no delirium group. Elevated choline and reduced NAA indicate inflammatory processes and white matter damage as well as neuronal metabolic impairment. Further research is needed to separate the choline peaks, as well as more detailed collection of medication regimens to determine whether a higher choline concentration is a function of the delirium process or cancer treatment effects.