Cyclosporine induces neuronal apoptosis and selective oligodendrocyte death in cortical cultures

Case report: Cyclosporine A-induced extrapyramidal syndrome following hematopoietic stem cell transplantation

Introduction

Cyclosporine A-associated neurotoxicity has been reported in up to 40% of patients and its wide range of neurological adverse effects have been reported, ranging from mild tremors to fatal leukoencephalopathy. Extrapyramidal (EP) neurotoxicity is a rare manifestation of cyclosporine. Cyclosporine-induced extrapyramidal syndrome remains a rare adverse reaction.

Design/methods

A database search was performed for studies in patients from all age groups. We found a total of 10 articles reporting EP as an adverse effect of cyclosporine A. A total of 16 patients were found, and a thorough review of these patients was performed. A comparison of patients was performed to highlight common clinical presentations, investigations during the symptomatic phase, and prognosis. In addition, we describe an 8-year-old boy who developed cyclosporine-related extrapyramidal signs on day 60 post-hematopoietic stem cell transplantation for beta-thalassemia.

Conclusion

Cyclosporine A can induce neurotoxicity resulting in diverse symptoms. Signs of EP are rare manifestations of cyclosporine neurotoxicity and should be considered when evaluating post-transplant recipients of cyclosporine when they are present with any EP symptoms. Discontinuation of cyclosporine results in good recovery in most patients.

Acute Graft-Versus-Host Disease, Infections, Vascular Events and Drug Toxicities Affecting the Central Nervous System

Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative therapy for patients with hematological malignancies. Acute Graft versus host diseases (GVHD) is a major immune mediated side effect of allo-HCT that can affect the central nervous system (CNS) in addition to post-allo-HCT vascular events, drug toxicity or infections. Here we summarize and discuss recent preclinical data on the CNS as a target of acute GVHD and the known mechanisms contributing to neurotoxicity with a focus on microglia and T cells. We also discuss open questions in the field and place the findings made in mouse models in a clinical context. While in mice the neurological deficits can be assessed in a controlled fashion, in patients the etiology of the CNS damage is difficult to attribute to acute GVHD versus infections, vascular events, and drug-induced toxicity. Ultimately, we discuss novel therapies for GVHD of the CNS. Our understanding of the biological mechanisms that lead to neurotoxicity after allo-HCT increased over the last decade. This review provides insights into CNS manifestations of GVHD versus other etiologies of CNS damage in mice and patients.

Tacrolimus Decreases Cognitive Function by Impairing Hippocampal Synaptic Balance: a Possible Role of Klotho

The influence of long-term tacrolimus treatment on cognitive function remains to be elucidated. Using a murine model of chronic tacrolimus neurotoxicity, we evaluated the effects of tacrolimus on cognitive function, synaptic balance, its regulating protein (Klotho), and oxidative stress in the hippocampus. Compared to vehicle-treated mice, tacrolimus-treated mice showed significantly decreased hippocampal-dependent spatial learning and memory function. Furthermore, tacrolimus caused synaptic imbalance, as demonstrated by decreased excitatory synapses and increased inhibitory synapses, and downregulated Klotho in a dose-dependent manner; the downregulation of Klotho was localized to excitatory hippocampal synapses. Moreover, tacrolimus increased oxidative stress and was associated with activation of the PI3K/AKT pathway in the hippocampus. These results indicate that tacrolimus impairs cognitive function via synaptic imbalance, and that these processes are associated with Klotho downregulation at synapses through tacrolimus-induced oxidative stress in the hippocampus.

Tacrolimus induced optic neuropathy in post-lung transplant patients: A series of 3 patients

Purpose

Tacrolimus is a commonly used immunosuppressant medication after lung transplantation. In rare cases, tacrolimus causes a medication-induced optic neuropathy (TON) that can lead to significant vision loss.

Observations

In this series, we describe three cases of TON, 1-10 years after medication use. Two patients were young (22yr and 33yr) females with cystic fibrosis. The last case was a 65yr male with idiopathic pulmonary fibrosis. In 2/3 cases tacrolimus serum levels were normal. Visual acuity ranged from 20/20 to 20/300, and vision loss occurred acutely to sub-acutely, over a span of 2-3 months.

Conclusions and importance

As presented here, TON can be highly variable. MRI findings are often non-specific, from normal brain findings to extensive white matter changes. There remains an unclear association with graft-versus-host disease and reduced kidney function. Visual findings are often subtle, including color vision aberration and peripheral visual field deficits, both of which usually require an ophthalmologic evaluation. When diagnosed in a timely fashion, TON is at least partially reversible in up to half of all cases. While rare, the cases described here support post-lung transplant ophthalmologic evaluation in those taking high-risk medications.

Risk Factor and Long-Term Outcome Analyses for Acute Limbic Encephalitis and Calcineurin Inhibitor-Induced Encephalopathy in Adults following Allogeneic Hematopoietic Cell Transplantation

Post-transplantation acute limbic encephalitis (PALE) is a rare, severe inflammatory disorder in the bilateral limbic system, including the hippocampus. To date, only a few studies have reported details, including risk factors for PALE; however, further clinical evidence of PALE, especially in cerebrospinal fluid human herpesvirus 6-negative cases, is warranted. In addition, data are sparse regarding the risk factors for calcineurin inhibitor (CNI)-induced encephalopathy (CNIE) following allogeneic hematopoietic cell transplantation (allo-HCT) in adults. Therefore, we examined the risk factors for and clinical details of PALE and CNIE. We retrospectively analyzed consecutive patients who underwent allo-HCT between January 2005 and November 2017. A total of 485 patients age 46 years (median) were eligible. In total, 14 PALE cases and 11 CNIE cases were identified. Multivariable analyses identified older age, use of an HLA-mismatched unrelated donor (URD), graft-versus-host disease (GVHD) prophylaxis with CNI and mycophenolate mofetil, and grade II-IV acute GVHD as significantly associated with an increased risk of PALE. In 13 patients who received high-dose methylprednisolone (mPSL) therapy, 6 (46%) responded to mPSL therapy, and 3 (23%) achieved complete remission at day 90 after mPSL administration. Furthermore, myelodysplastic syndrome (MDS), HLA-mismatched URD, and grade II-IV acute GVHD were significantly associated with an increased risk of CNIE. The 5-year nonrelapse mortality rate was 50% in PALE and 63% in CNIE, suggesting a very poor prognosis. In conclusion, this study provides evidence that HLA-mismatched URD and acute GVHD may independently contribute to the development of PALE, possibly in part through HLA-mismatch-derived alloimmune responses. Other than acute GVHD, we have identified MDS and HLA-mismatched URD as novel predictors of CNIE after allo-HCT.

Immunosuppression-related neurological disorders in kidney transplantation

A large number of neurological disorders can affect renal transplant recipients, potentially leading to disabling or life-threatening complications. Prevention, early diagnosis and appropriate management of these conditions are critical to avoid irreversible lesions. A pivotal role in the pathogenesis of common post-transplant neurological disorders is played by immunosuppressive therapy. The most frequently administered regimen consists of triple immunosuppression, which comprises a calcineurin inhibitor (CNI), a purine synthesis inhibitor and glucocorticoids. Some of these immunosuppressive drugs may lead to neurological signs and symptoms through direct neurotoxic effects, and all of them may be responsible for the development of tumors or opportunistic infections. In this review, after a brief summary of neurotoxic pathogenetic mechanisms encompassing recent advances in the field, we focus on the clinical presentation of more common and severe immunosuppression-related neurological complications, classifying them by characteristics of urgency and anatomic site. Our goal is to provide a general framework that addresses such clinical issues with a multidisciplinary approach, as these conditions require.

Tacrolimus Optic Neuropathy

BACKGROUND

Tacrolimus (FK506, Prograf) is a potent immunosuppressant, which inhibits cytokine synthesis and blocks T-cell development. Optic neuropathy from tacrolimus toxicity is very uncommon but, when present, can result in severe vision loss.

METHODS

Case series and review of the literature.

RESULTS

We present 3 patients with tacrolimus optic neuropathy after bone marrow transplantation complicated by graft-vs-host disease and demonstrate the differing clinical and radiologic presentation of this presumed toxic optic neuropathy.

CONCLUSIONS

Tacrolimus optic neuropathy can manifest in a multitude of clinical presentations and can have devastating visual consequences.

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.

Tacrolimus-Induced Pain Syndrome After Bone Marrow Transplantation: A Case Report and Literature Review

BACKGROUND

Calcineurin-inhibitor-induced pain syndrome (CIPS), a rare complication seen in patients with bone marrow transplants, is associated with the use of cyclosporine A (CsA) or tacrolimus (FK506). This case demonstrates the successful pain control of FK506-related CIPS in a 23-year-old male patient with previously reported characteristic clinical features of CIPS in addition to neuropathic symptoms and uncharacteristic imaging findings. On day 15 after the transplantation, the patient complained of severe pain in the lower limbs. Afterwards, the patient started to complain of pain on his hands and back too. During this period, FK506 levels ranged from 9.5 to 16.1 ng/mL. All laboratory exams were normal, except for an increased level of alkaline phosphatase (141 U/L). The pain was not ameliorated by various analgesic drugs. Although MRI done for our patient showed no typical radiological signs such as bone marrow edema, CIPS was suggested based on characteristic clinical features of CIPS. Of note, our patient's pain had neuropathic pain-like characteristics, unlike the pain in previously reported patients with CIPS.

CONCLUSION

The patient was treated successfully by switching FK506 to CsA and administrating gabapentin and nifedipine. Heightened awareness of this complication after bone marrow transplants may be needed for hematologists, otherwise CIPS can result in catastrophic consequences.

Comparative Analysis of Zearalenone Effects on Thyroid Receptor Alpha (TRα) and Beta (TRβ) Expression in Rat Primary Cerebellar Cell Cultures

Thyroid receptors play an important role in postnatal brain development. Zearalenone (ZEN), a major mycotoxin of Fusarium fungi, is well known to cause serious health problems in animals and humans through various mechanisms, including the physiological pathways of thyroid hormone (TH). In the present study, we aimed to investigate the expression of thyroid receptors α (TRα) and β (TRβ) in primary cerebellar neurons in the presence or absence of glia and following ZEN treatment, using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot. Primary cerebellar granule cells were treated with low doses of ZEN (0.1 nM) in combination with physiologically relevant concentrations of l-thyroxine (T4), 3,3′,5-triiodo-l-thyronine (T3) and 17β-estradiol (E2). Expression levels of TRα and TRβ at mRNA and protein levels were slightly modified by ZEN administered alone; however, along with thyroid and steroid hormones, modelling the physiological conditions, expression levels of TRs varied highly depending on the given treatment. Gene expression levels were also highly modulated by the presence or absence of glial cells, with mostly contrasting effects. Our results demonstrate divergent transcriptional and translational mechanisms involved in the expression of TRs implied by ZEN and hormonal milieu, as well as culturing conditions.

A 10-year monitoring of the eyesight in patients after kidney transplantation

A pilot study of a 10-year analysis of the eyesight characteristics in patients after renal transplantation with a view to a later wider study of the same population.The study encompassed 50 eyes in 25 patients who underwent renal transplantation in the years 2007 and 2008. All patients underwent: visual acuity measurement, tonometry, slit lamp examination, and spectroscopic optical coherence tomography.Changes in the eyes observed during the 10-year observation period included mostly: cataract (48%), hypertensive angiopathy (28%), diabetic macular edema (16%), and glaucoma (16%). Ten years after the renal transplant visual acuity declined in 15 patients (60%). In 67% of those with eyesight deterioration the cause was cataract, while in patients with no changes in the eyesight (n = 10) cataract was diagnosed only in one. Patients with cataracts had been more often treated with cyclosporine, and that difference was statistically significant (73% vs 21%; P < .05). Comparing patients with hypertensive angiopathy with controls has shown that in the first group creatinine levels were statistically significantly higher (1.6 vs 1.16 mg/dL; P < .05). Patients with angiopathy had been also longer on renal replacement therapy before transplant (57 vs 26 months, P > .05), and this group included also statistically more persons after retransplantation (43% vs 5%, P < .05).Most frequent ophthalmological diagnoses in patients after a kidney transplant include cataract, diabetic retinopathy, and hypertensive angiopathy. Visual acuity deterioration was seen in 60% of patients and was mainly the effect of cataract progress. The effect of cyclosporine on cataract progress was significant. The diagnosis of hypertensive angiopathy corresponded with poorer function of the transplanted kidney.

Early and late neurological complications of liver transplantation in pediatric patients

NCs occur commonly after solid organ transplantation and affect 15%-30% of liver transplant recipients. The aim of this retrospective study was to evaluate the type and incidence of neurologic events in pediatric patients following LT. Between May 2006 and June 2015, 242 patients (118 females, 124 males) requiring LT for different etiologies at the İnönü University Liver Transplantation Institute were included. The incidence, types, and risk factors of NCs that occurred following LT were evaluated retrospectively. Neurologic events occurred in 57 (23.5%) of the patients. Early NCs were encephalopathy (12.4%), seizures (11.5%), and PRES (7%). Of 57 patients, five (8.7%) experienced NCs at least 1 month after LT; these late NCs included tremor, headaches, encephalopathy, ataxia, and neuropathy. The psychiatric symptoms after LT were noted in 42 patients (17.4%). The mortality rate after LT in those with or without neurological events was not significantly different (P=.73). There was a high incidence of serious neurologic events after LT. The major neurologic manifestation in our patients was encephalopathy followed by seizures.

Neurologic Complications after Allogeneic Hematopoietic Stem Cell Transplantation

Neurologic complications after hematopoietic stem cell transplantation are frequently life-threatening, and their clinical management can be highly challenging. A wide spectrum of causative factors-including drug-related toxicities; infections sustained by virus, bacteria, or invasive molds; metabolic encephalopathy; cerebrovascular disorders; immune-mediated disorders; and disease recurrence-may lead to potentially lethal complications. Moreover, given that some neurologic complications are not uncommonly diagnosed post mortem, their overall incidence is likely to be underestimated. Their prompt recognition and timely treatment are of paramount importance to reduce the risk for transplantation-related death.

Review ■ : Insulin-like Growth Factor-I and Apoptosis in Glial Cell Biology

Insulin-like growth factor-I (IGF-I) is a potent trophic factor capable of promoting both survival and differentiation of neurons and glia. This review examines the role of IGF-I and apoptosis in oligodendrocyte and Schwann cell biology in vitro and in vivo. Apoptosis is an essential element of development, homeostasis, and disease. IGF-I protects oligodendrocytes and Schwann cells from apoptosis during development and after apoptotic stimuli. Transgenic mouse models, which ablate or increase expression of IGF-I, have abnormal oligodendrocytes and myelin formation. A more thorough understanding of the protective mechanism of IGF-I in oligodendrocytes and Schwann cells will aid in its precise application in treating a variety of neurologic disorders. NEUROSCIENTIST 6:39-47, 2000

Prevention of recurrent episodes of rhabdomyolysis with tacrolimus in a transplant recipient with myopathy

Genetic muscular disorders are known risk factors for rhabdomyolysis, which may result in acute kidney injury. Recurrent episodes of acute kidney injury can lead to chronic kidney disease and eventually end-stage renal failure. We describe a patient with chronic kidney disease that developed in the setting of recurrent rhabdomyolysis, resulting in the requirement for renal transplantation. After transplantation, the maintenance of tacrolimus trough concentrations above what is typically prescribed for standard renal transplant recipients appeared to confer protection from further episodes of rhabdomyolysis. This is consistent with previous case series that demonstrated a therapeutic benefit of the calcineurin inhibitor cyclosporine in collagen VI myopathies in the nontransplant population. This case report suggests the potential application of higher tacrolimus targets in patients who have undergone renal transplantation in the setting of recurrent rhabdomyolysis leading to end-stage renal failure.

Bilateral Inflammatory Optic Neuropathy Related to Graft versus Host Disease Following Allogeneic Bone Marrow Transplantation for Hodgkin Disease

Graft versus host disease (GvHD) is a common and often troublesome complication of allogeneic bone marrow transplantation. Neurological complications usually involve the peripheral nervous system and muscle, but the central nervous system may be affected. When an optic neuropathy develops, it is often difficult to determine the cause quickly; infective complications and drug toxicity may have arisen, but an inflammatory disorder due to GvHD should also be considered, particularly since treatment with steroids and immune suppression may improve the outcome significantly. This brief case report shows how this may be the case and reviews our current understanding of the pathophysiology and treatment of the disorder within the nervous system.

Risk factors for neurological complications and their correlation with survival following pediatric liver transplantation

Despite the improved outcomes of LT, post-operative NCs remain a significant cause of morbidity and mortality. The aim of the study was to identify the incidence of and risk factors for NCs in children who underwent LT. The medical records of pediatric patients who underwent LT at Asan Medical Center Children's Hospital between January 1994 and December 2010 were retrospectively analyzed. The onset and types of NC and pretransplant variables associated with NC were evaluated. We identified 190 children (85 boys [44.7%], 105 girls [55.3%]) of mean age 4.1 ± 4.7 yr, who underwent LT. Forty-six NCs occurred in 41 (21.6%) patients after LT, the most common being seizures (n = 13, 28.3%) and encephalopathy (n = 10, 21.7%). Of the 46 NCs, 24 (52.2%) occurred within three months after LT. Multivariate analysis showed that primary liver disease, preoperative neurological problems, preoperatively higher serum creatinine concentration, and graft failure were significant risk factors for NCs. The survival rate was significantly lower for patients with NCs than for those without (p < 0.001). NCs after pediatric LTs were common and associated with a higher mortality rate in our study. Close monitoring and appropriate risk management may improve the long-term outcomes of pediatric patients who undergo LT.

Neurotoxicity of commonly used hepatic drugs

Neurologic complications are common side-effects of immunosuppressive medications used in the prevention of graft rejection after organ transplantation. The medications most commonly encountered include the calcineurin inhibitors and mycophenolate mofetil. Depression is the most commonly encountered neurotoxicity; however, severe but rare adverse neurological effects related to these therapies have been reported. Interferons, ribavirin, and protease inhibitors are therapeutic options commonly encountered in the treatment of hepatitis. Nucleoside analogs such as adefovir dipivoxil and entecavir carry significant risks for the development of lactic acidosis and hepatic dysfunction; however, most common adverse effects to these therapies in general are mild. While the mechanisms of action are poorly elucidated, they are discussed along with treatment strategies.

Central pontine myelinolysis: a case report and clinical-pathological review

An 11-yr-old child presented with acute mental status changes and spastic quadriplegia after orthotopic liver transplantation. Magnetic resonance (MR) imaging findings were consistent with central pontine and EPM. Initial immunosuppression included tacrolimus, mycophenolate mofetil, and corticosteroids. Given that neurotoxicity is a well-established side effect of CNI, the patient was converted to rapamycin and subsequently experienced significant neurologic recovery. The temporal resolution of the patient's symptoms suggests that prompt recognition of central pontine and EPM and conversion from tacrolimus to rapamycin during the early post-operative course may have therapeutic benefits for patients undergoing pediatric transplant with CNI-related neurotoxicity.

Calcineurin serves in the circadian output pathway to regulate the daily rhythm of L-type voltage-gated calcium channels in the retina

The L-type voltage-gated calcium channels (L-VGCCs) in avian retinal cone photoreceptors are under circadian control, in which the protein expression of the α1 subunits and the current density are greater at night than during the day. Both Ras-mitogen-activated protein kinase (MAPK) and Ras-phosphatidylionositol 3 kinase-protein kinase B (PI3K-AKT) signaling pathways are part of the circadian output that regulate the L-VGCC rhythm, while cAMP-dependent signaling is further upstream of Ras to regulate the circadian outputs in photoreceptors. However, there are missing links between cAMP-dependent signaling and Ras in the circadian output regulation of L-VGCCs. In this study, we report that calcineurin, a Ca2+/calmodulin-dependent serine (ser)/threonine (thr) phosphatase, participates in the circadian output pathway to regulate L-VGCCs through modulating both Ras-MAPK and Ras-PI3K-AKT signaling. The activity of calcineurin, but not its protein expression, was under circadian regulation. Application of a calcineurin inhibitor, FK-506 or cyclosporine A, reduced the L-VGCC current density at night with a corresponding decrease in L-VGCCα1D protein expression, but the circadian rhythm of L-VGCCα1D mRNA levels were not affected. Inhibition of calcineurin further reduced the phosphorylation of ERK and AKT (at thr 308) and inhibited the activation of Ras, but inhibitors of MAPK or PI3K signaling did not affect the circadian rhythm of calcineurin activity. However, inhibition of adenylate cyclase significantly dampened the circadian rhythm of calcineurin activity. These results suggest that calcineurin is upstream of MAPK and PI3K-AKT but downstream of cAMP in the circadian regulation of L-VGCCs.

Cyclosporine immunomodulation retards regeneration of surgically transected corneal nerves

PURPOSE

To determine whether immunomodulation with cyclosporine (CsA) affects reinnervation after surgical transection of stromal nerves.

METHODS

Thy1-YFP+ neurofluorescent mice underwent lamellar corneal surgery and 3 days later, received artificial tears or CsA eye drops for 6 weeks. Serial in vivo wide-field stereofluorescent microscopy was performed to determine changes in nerve fiber density (NFD). Real-time quantitative PCR was performed to determine the expression of neurotrophins and cytokines (IL6 and TNF-α). Compartmental culture of trigeminal ganglion neurons was performed in Campenot devices to determine whether CsA directly affects neurite outgrowth.

RESULTS

Yellow fluorescent protein (YFP)-positive cells significantly increased at 3 and 7 days after surgery. The number of YFP-positive cells in the cornea was significantly lower in the CsA group than that in the control group. The percentage increase in NFD between 2 to 6 weeks was greater in the control group (80% ± 10%, P = 0.05) than that in the CsA group (39% ± 21%). The CsA group also exhibited lower expression of IL6 and TNF-α (P = 0.01). In compartmental culture experiments, neurite outgrowth toward side compartments containing CsA was significantly less (2.29 ± 0.4 mm, P = 0.01) than that toward side compartments containing vehicle (3.97 ± 0.71 mm).

CONCLUSIONS

Immunomodulation with CsA reduces the expression of cytokines (IL6) in the cornea and retards regenerative sprouting from transected corneal stromal nerve trunks. In addition, CsA has a direct growth inhibitory action on neurites as well.

Limiting spinal cord injury by pharmacological intervention

The direct primary mechanical trauma to neurons, glia and blood vessels that occurs with spinal cord injury (SCI) is followed by a complex cascade of biochemical and cellular changes which serve to increase the size of the injury site and the extent of cellular and axonal loss. The aim of neuroprotective strategies in SCI is to limit the extent of this secondary cell loss by inhibiting key components of the evolving injury cascade. In this review we will briefly outline the pathophysiological events that occur in SCI, and then review the wide range of neuroprotective agents that have been evaluated in preclinical SCI models. Agents will be considered under the following categories: antioxidants, erythropoietin and derivatives, lipids, riluzole, opioid antagonists, hormones, anti-inflammatory agents, statins, calpain inhibitors, hypothermia, and emerging strategies. Several clinical trials of neuroprotective agents have already taken place and have generally had disappointing results. In attempting to identify promising new treatments, we will therefore highlight agents with (1) low known risks or established clinical use, (2) behavioral data gained in clinically relevant animal models, (3) efficacy when administered after the injury, and (4) robust effects seen in more than one laboratory and/or more than one model of SCI.

Unilateral tacrolimus-associated optic neuropathy after liver transplantation

BACKGROUND

Tacrolimus has been associated with several ocular adverse effects, such as optic neuropathy.

METHODOLOGY/PRINCIPAL FINDINGS

A 56-year-old woman noted sudden, severe, painless visual loss in her left eye. She had undergone liver transplantation for alcoholic related cirrhosis 6 months before. Her chronic immunosuppressive regimen consisted of prednisone and tacrolimus at dosage of 1.5 mg orally once daily. Consequently, the patient developed a left optic neuropathy.

CONCLUSION/SIGNIFICANCE

We report the first case of unilateral optic neuropathy associated with oral tacrolimus medication. Surgeons and ophthalmologists must evaluate ocular symptoms in the post-transplantation period, and suspicion should be maintained even if unilaterality or asymmetry of symptoms against a toxic etiology.

Analytic Review: Neurological Complications of Transplantation

Recipients of solid organ or hematopoietic cell transplants are at risk of life-threatening neurological disorders including encephalopathy, seizures, infections and tumors of the central nervous system, stroke, central pontine myelinolysis, and neuromuscular disorders—often requiring admission to, or occurring in, the intensive care unit (ICU). Many of these complications are linked directly or indirectly to immunosuppressive therapy. However, neurological disorders may also result from graft versus host disease, or be an expression of the underlying disease which prompted transplantation, as well as injury induced during radiation, chemotherapy, surgery, and ICU stay. In rare cases, neuroinfectious pathogens may be transmitted with the transplanted tissue or organ. Diagnosis may be a challenge because clinical symptoms and findings on neuroimaging lack specificity, and a biological specimen or tissue diagnosis is often needed for definitive diagnosis. Management is centered on preventing further neurological injury, etiology-targeted therapy, and balancing the benefits and toxicities of specific immunosuppressive agents.

OLIGODENDROCYTE VULNERABILITY FOLLOWING TRAUMATIC BRAIN INJURY IN RATS: EFFECT OF MODERATE HYPOTHERMIA

The purpose of this study was to document patterns of oligodendrocyte vulnerability to TBI and determine whether posttraumatic hypothermia prevents oligodendrocyte cell loss. Sprague Dawley rats underwent moderate fluid percussion brain injury. Thirty minutes after TBI, brain temperature was reduced to 33°C for 4 hrs or maintained at normothermic levels (37°C). Animals were perfusion-fixed for quantitative immunohistochemical analysis at 3 (n=9) or 7 (n=9) days post-TBI. Within the cerebral cortex, external capsule and corpus callosum, numbers of APC-CC1 immunoreactive oligodendrocytes at 3 and 7 days following TBI were significantly decreased compared to sham operated rats (p<0.02). Double-labeling studies showed that vulnerable oligodendrocytes expressed increased Caspase 3 activation compared to sham. Posttraumatic hypothermia significantly reduced the number of CC1 positive oligodendrocytes lost after normothermia TBI in white matter tracts (p<0.01). This model of TBI leads to quantifiable regional patterns of oligodendrocyte vulnerability. Posttraumatic hypothermia protects oligodendrocytes by interfering with Caspase 3-mediated cell death mechanisms. Therapeutic hypothermia may improve functional outcome by attenuating trauma-induced oligodendrocyte cell death, subsequent demyelination and circuit dysfunction.

Cyclosporin A increases recovery after spinal cord injury but does not improve myelination by oligodendrocyte progenitor cell transplantation

BACKGROUND

Transplantation of oligodendrocyte precursor cells (OPCs) is an attractive therapy for demyelinating diseases. Cyclosporin A (CsA) is one of the foremost immunosuppressive agents and has widespread use in tissue and cell transplantation. However, whether CsA affects survival and differentiation of engrafted OPCs in vivo is unknown. In this study, the effect of CsA on morphological, functional and immunological aspects, as well as survival and differentiation of engrafted OPCs in injured spinal cord was explored.

RESULTS

We transplanted green fluorescent protein (GFP) expressed OPCs (GFP-OPCs) into injured spinal cords of rats treated with or without CsA (10 mg/kg). Two weeks after cell transplantation, more GFP-positive cells were found in CsA-treated rats than that in vehicle-treated ones. However, the engrafted cells mostly differentiated into astrocytes, but not oligodendrocytes in both groups. In the CsA-treated group, a significant decrease in spinal cord lesion volume along with increase in spared myelin and neurons were found compared to the control group. Such histological improvement correlated well with an increase in behavioral recovery. Further study suggested that CsA treatment could inhibit infiltration of T cells and activation of resident microglia and/or macrophages derived from infiltrating monocytes in injured spinal cords, which contributes to the survival of engrafted OPCs and repair of spinal cord injury (SCI).

CONCLUSIONS

These results collectively indicate that CsA can promote the survival of engrafted OPCs in injured spinal cords, but has no effect on their differentiation. The engrafted cells mostly differentiated into astrocytes, but not oligodendrocytes. The beneficial effect of CsA on SCI and the survival of engrafted cells may be attributed to its neuroprotective effect.

[Ciclosporin-associated cerebral tumor-like location of Behçet's disease]

INTRODUCTION

Cerebral tumor-like location is uncommon in the course of Behçet's disease. We report herein a patient with tumor-like lesions associated with ciclosporin therapy.

CASE REPORT

A 45-year-old male treated for 17 years with colchicine and ciclosporin for Behçet's disease with cutaneomucosal, ocular and joint involvement was admitted for sudden onset of meningo-encephalitis with lymphocytic meningitis. CT-scan showed a nodular lesion of the brainstem enhanced by iodine. Ciclosporin was discontinued; prednisone and IV cyclophosphamide were started. After three months of favorable outcome, a relapse occurred when ciclosporin was started again. MRI showed two additional capsulothalamic lesions. Prednisone and cyclophosphamide were started again with a favorable response and minimal sequelae.

CONCLUSION

The main challenge in cerebral tumor-like location of Behçet's disease is to rule out other inflammatory or tumor processes. Neuronal toxicity of ciclosporin limits indications for this therapy in Behçet's disease.

DNA damage-inducing agents elicit gamma-secretase activation mediated by oxidative stress

According to the amyloid cascade hypothesis, Alzheimer's disease is the consequence of neuronal cell death induced by beta-amyloid (Abeta), which accumulates by abnormal clearance or production. On the other hand, recent studies have shown cell death-induced alteration in amyloid precursor protein (APP) processing, suggesting potential mutual interactions between APP processing and cell death. We have shown previously that the cell death caused by DNA damage-inducing agents (DDIAs) facilitated gamma-secretase activity and Abeta generation in a Bax/Bcl-2-dependent, but caspase-independent manner. Here, we attempted to elucidate the downstream mechanism that modulates gamma-secretase activity in DDIA-treated cells. N-acetyl cysteine, a potent antioxidant, attenuated DDIA-induced enhancement of gamma-secretase activity but failed to rescue cell death. Overexpression of heat shock protein 70, which blocks cytochrome c release from mitochondria, also reduced gamma-secretase activity. Moreover, glutathione depletion significantly facilitated gamma-secretase activity and Abeta generation by enhancing the formation of higher molecular weight gamma-secretase complex before signs of cell death developed. Finally, Abeta treatment, a known inducer of oxidative stress, also increased gamma-secretase activity. Taken together, these results indicate that DDIA-induced gamma-secretase activation is dependent on augmented oxidative stress, and that Abeta and gamma-secretase may activate each other. On the basis of these results, we propose a feed-back loop between oxidative stress and Abeta generation mediated by gamma-secretase activation.

Calcineurin-inhibitor-induced pain syndrome after bone marrow transplantation

Calcineurin-inhibitor-induced pain syndrome (CIPS), a rare complication seen in patients with organ transplants, is associated with the use of calcineurin inhibitors (CIs) such as cyclosporine (CSP) and tacrolimus (FK). Patients with this syndrome usually present with severe leg pain. This case report demonstrates the successful pain control of this pain syndrome in a 42-year-old female patient who had been given CIs (FK and CSP) as an immunosuppressive agent after a bone marrow transplant. Twenty-one days after the transplantation, she complained of severe pain in her bilateral lower extremities; this lasted several weeks, and was resistant to ordinary analgesics such as intramuscular pentazocine, intravenous morphine, and even oral nifedipine, which is generally accepted as an effective analgesic agent for the pain in this syndrome. Due to the presence of allodynia, our patient's pain had neuropathic pain-like characteristics, unlike the pain in previously reported patients with other organ transplants. Her pain was successfully relieved by the administration of oral amytriptyline, clonazepam, oxycodone, and intravenous lidocaine, all of which ordinarily have an analgesic effect on neuropathic pain. CIPS in patients with hematopoietic stem cell transplants treated with FK may have a mechanism by which neuropathic pain may develop that is different from that in patients with other organ transplants.

Neurological complications after orthotopic liver transplantation

BACKGROUND

The number of orthotopic liver transplantation performed each year is increasing due to increased safety and logistic facilities. Therefore, the importance of reducing adverse events is progressively growing.

AIM

To review present knowledge on the neurological complications of orthotopic liver transplantation.

METHODS

The epidemiology, the clinical features and the pathophysiology of the neurological complications of orthotopic liver transplants, resulting from a systematic review of the literature in the last 25 years, are summarized.

RESULTS AND CONCLUSIONS

The review highlights that a relevant variety of neurological adverse events can occur in patients undergoing orthotopic liver transplantation. The knowledge of neurological complications of orthotopic liver transplantation is important for transplantation teams to reduce their prevalence and improve their management. In addition, the likelihood of neurological adverse effects provides evidence for the need of a careful cognitive and neurological work up of patients in the orthotopic liver transplantation waiting list, in order to recognize and interpret neurological dysfunction occurring after orthotopic liver transplantation.

High cyclophilin D content of synaptic mitochondria results in increased vulnerability to permeability transition

Mitochondria isolated from synaptosomes are more sensitive to Ca2+ overload and the resultant opening of the mitochondrial permeability transition pore (mPTP) than nonsynaptic mitochondria. To identify the mechanisms underlying these differences in Ca2+ dynamics, we examined relative levels of mPTP components in synaptic versus nonsynaptic mitochondria. Synaptic mitochondria had higher levels of cyclophilin D when compared with nonsynaptic mitochondria, whereas levels of the voltage-dependent anion channel and the adenine nucleotide translocase were similar in the two mitochondrial fractions. These differences in Ca2+ handling between synaptic and nonsynaptic mitochondria were greatly reduced in cyclophilin D null [Ppif-/- (peptidylprolyl isomerase F)] mice. Higher concentrations of cyclosporine A, which interacts with cyclophilin D to delay mPTP opening, were necessary to increase the Ca2+ uptake capacity of synaptic versus nonsynaptic mitochondria. To determine whether the differences in Ca2+ handling might reflect the relative abundance of neuronal and glial mitochondria in the two mitochondrial fractions, we compared cyclophilin D levels in primary cortical neurons and astrocytes. Primary rat cortical neurons possess higher cyclophilin D levels than do primary astrocytes. In the adult rat brain, cyclophilin D immunoreactivity was abundant in neurons but sparse in astrocytes. Together, these results demonstrate that the Ca2+ handling differences observed in synaptic versus nonsynaptic mitochondria are primarily the result of the high levels of cyclophilin D in synaptic mitochondria, reflecting the greater proportion of neuronal mitochondria in this fraction. The high levels of cyclophilin D in neuronal mitochondria result in their greater vulnerability to mPT and in higher levels of cyclosporine A being required to inhibit mPTP opening.

Caspase-dependent apoptosis induced by calcineurin inhibitors was prevented by glycogen synthase kinase-3 inhibitors in cultured rat cortical cells

Calcineurin is selectively enriched within neurons of the central nervous system. The mechanism of calcineurin inhibitor-induced neurotoxicity remains poorly understood. The purpose of this study is to examine whether glycogen synthase-3 (GSK-3) is involved in calcineurin inhibitor-induced apoptosis. Calcineurin inhibitors such as cyclosporine A (CsA) and FK506 increased apoptotic cell death with morphological changes characterized by cell shrinkage, nuclear condensation of fragmentation, and internucleosomal DNA fragmentation. Alsteropaullone and 1-azakenpaullone, GSK-3 inhibitors, prevented calcineurin inhibitor-induced apoptosis. In addition, insulin growth factor-I (IGF-I) and cycloheximide completely blocked cell death. Moreover, caspase-3 activation was accompanied by calcineurin inhibitor-induced cell death. These results suggest that calcineurin inhibitors induce caspase-dependent apoptosis and activation of GSK-3 is involved in cell death in rat cortical neurons.

Cell death in rat cerebellar granule neurons induced by hydrogen peroxide in vitro: mechanisms and protection by adenosine receptor ligands

Oxidative stress, resulting from excessive production of reactive oxygen species (ROS), is a pathological state that causes profound cellular damage and eventual death resulting from the overactivation of glutamate receptors, and the generation of nitric oxide, superoxide and hydrogen peroxide (H(2)O(2)). As such, H(2)O(2) represents an important model for studying the neuropathology of oxidative stress in a variety of CNS disorders. The effects of H(2)O(2) on the viability of post-natal cerebellar granule neurons (CGNs), the nature of the cell death involved and the potential protection by adenosine receptors against the damage were examined in the current study. Hydrogen peroxide (10-400 microM) reduced CGN viability in a concentration- and time-dependent manner. The addition of catalase (100 U/ml) prevented this effect, and the non-specific COX inhibitor aspirin (1 mM) also alleviated the damage. A combination of H(2)O(2) (5 microM) and Cu(2+) (0.5 mM) resulted in a significant damage that was not prevented by the hydroxyl radical scavenger mannitol (50 mM). The permeability transition pore blocker cyclosporin A, the caspase-3 inhibitor Z-DEVD-fmk (40 microM) and the PARP-1 inhibitor DPQ (10 microM) each significantly protected against peroxide damage. While the A(1) adenosine receptor agonist CPA and the A(2A) receptor antagonist ZM241385 (each at 100 nM) elicited protection, the A(1) adenosine receptor blocker DPCPX and the A(2A) receptor agonist CGS21680 (each at 100 nM) showed no effect. The data demonstrate that H(2)O(2) induced oxidative stress in CGNs, involving both apoptotic and necrotic death, and this can be ameliorated by A(1) receptor activation or A(2A) receptor blockade.

Evidence that intracellular cyclophilin A and cyclophilin A/CD147 receptor-mediated ERK1/2 signalling can protect neurons against in vitro oxidative and ischemic injury

We previously reported that cyclophilin A protein is up-regulated in cortical neuronal cultures following several preconditioning treatments. In the present study, we have demonstrated that adenoviral-mediated over-expression of cyclophilin A in rat cortical neuronal cultures can protect neurons from oxidative stress (induced by cumene hydroperoxide) and in vitro ischemia (induced by oxygen glucose deprivation). We subsequently demonstrated that cultured neurons, but not astrocytes, express the recently identified putative cyclophilin A receptor, CD147 (also called neurothelin, basigin and EMMPRIN), and that administration of purified cyclophilin A protein to neuronal cultures induces a rapid but transient phosphorylation of the extracellular signal-regulated kinase (ERK) 1/2. Furthermore, administration of purified cyclophilin A protein to neuronal cultures protects neurons from oxidative stress and in vitro ischemia. Interestingly, we detected up-regulation of cyclophilin A mRNA, but not protein in the hippocampus following a 3-min period of sublethal global cerebral ischemia in the rat. Despite our in vivo findings, our in vitro data show that cyclophilin A has both intracellular- and extracellular-mediated neuroprotective mechanisms. To this end, we propose cyclophilin A's extracellular-mediated neuroprotection occurs via CD147 receptor signalling, possibly by activation of ERK1/2 pro-survival pathways. Further characterization of cyclophilin A's neuroprotective mechanisms may aid the development of a neuroprotective therapy.

Critical roles of Src family tyrosine kinases in excitatory neuronal differentiation of cultured embryonic stem cells

Embryonic stem (ES) cells have been tested for potential cell transplantation therapy for CNS disorders. Understanding their differentiation mechanism and identifying factors involved in driving excitatory and inhibitory neuron lineages should enhance the efficacy and efficiency of the cell transplantation therapy. We tested the hypothesis that selective expression of Src family tyrosine kinases is required for phenotype-specific differentiation and functional maturation of ES cell derived neurons. Cultured mouse pluripotent ES cells were treated with retinoic acid (RA) to induce neural differentiation. After RA induction, neurons derived from ES cells showed significant neurite growth, increased expression of Src, Fyn and Lck and an extension of Src kinase expression from cell body to neurite processes. ES cell derived neuron-like cells expressed neurofilament, synaptophysin, glutamate receptors, NMDA and kainate currents, became vulnerable to excitotoxicity and formed functional excitatory synapses. These developmental events were blocked or attenuated when cells were grown in the presence of Src family kinase inhibitor PP2. However, there was no change in the expression of GABAergic-specific protein GAD67 during PP2 treatment. Our data suggest that Src tyrosine kinases are involved in the terminal differentiation of excitatory neuronal phenotype during ES cell neural differentiation after RA induction.

Calcineurin Inhibitor-Induced Irreversible Neuropathic Pain after Allogeneic Hematopoietic Stem Cell Transplantation

The calcineurin inhibitors (CIs) cyclosporine A and tacrolimus are essential for graft-versus-host disease prophylaxis but are associated with adverse effects, including neurotoxicity. We report a case of irreversible CI-induced neuropathic pain following allogeneic hematopoietic stem cell transplantation. The patient developed dysesthesia, electric shock-like pain, and severe itching followed by intractable analgesic-resistant pain in the lower extremities. There were no abnormal radiographic findings, and there was no improvement with a reduction of CI dosage or with administration of a calcium channel blocker. These clinical findings are similar to but inconsistent with CI-induced musculoskeletal pain syndromes previously reported in organ transplantation.

Does Chronic Low-Dose Treatment With Cyclosporine Influence the Brain? A Histopatological Study in Pigs

Twenty percent of the patients immunosuppressed with cyclosporine A (CsA) develop neurological side effects such as tremor, paresthesias, headache, seizures, visual disorders, paresis, and coma-CsA encephalopathy. The encephalopathy resolves on CsA discharge; autopsies of recovered patients are normal. Characteristic lesions are seen on magnetic resonance imaging (MRI) during the period of encephalopathy. MRI of asymptomatic patients receiving CsA as well as most recovered patients are normal. Several theories of pathogenesis have been proposed, but none has been firmly established. The current placebo-controlled study, blinded to the investigator, was accordingly initiated to elucidate histopathological changes in the brain. Twelve adult Göttingen minipigs were randomized into two groups treated with either low-dose CsA (10 mg/kg/d) or no treatment for 6 months. Behavior, blood pressure, and blood parameters were measured throughout the study. All animals had a cerebral MRI before sacrifice. Three control pigs and one CsA-treated pig died during observation and were excluded from the study. None of the remaining eight pigs displayed behavioral signs or MRI-visible lesions characteristic of CsA encephalopathy. The brains appeared all normal on the gross pathological examination, but microscopy revealed perivascular, meningeal, and neuronal tissue infiltration with granulocytes and mononuclear cells in one CsA-treated pig, while the remaining pigs were without histopathological lesions. Pathological changes were noticed in one out of five CsA-treated animals, corresponding to the percentage of patients treated with CsA who develop CsA encephalopathy. To pursue this finding, two studies, one using CsA 20 mg/kg/d for 6 months and one using CsA 10 mg/kg/d for 12 months, have been initiated.

Pluripotent fates and tissue regenerative potential of adult olfactory bulb neural stem and progenitor cells

Neural stem cells and progenitor cells reside in the adult olfactory bulb (OB) core of mouse, rat, and human. Adult rodent OB core cells have the capacities for self-renewal and multipotency and form neurospheres. The differentiation fates of these neurosphere-forming cells were studied in vitro and in vivo. Adult OB neurospheres were comprised of stem cells and neuronal and glial progenitor cells. OB neurospheres in co-culture with primary embryonic striatal neurons and cortical neurons generated cells with morphological and neurochemical phenotypes of striatal and cortical neurons, respectively. Transplanted OB cells, delivered as dissociated cells or as intact neurospheres, dispersed, survived for long-term, extended neurites, migrated, expressed neuronal or glial markers, and formed synapses with host neurons when placed into the environment of the nonlesioned and lesioned central nervous system (CNS). Grafted cells in the CNS also showed angiogenic capacity by forming blood vessels. In a model of spinal motor neuron degeneration, adult OB neurosphere cells transplanted into lesioned spinal cord adopted phenotypes of motor neurons and had a robust potential to become oligodendrocytes. OB core cells in co-culture with skeletal myoblasts generated skeletal muscle cells. Chimeric skeletal muscle was formed when mouse OB neurospheres were transplanted into rat skeletal muscle. Within skeletal muscle, adult OB neurosphere cells became myogenic progenitor cells to form myotubes de novo. We conclude that the adult mammalian OB is a source of pluripotent neural stem cells and progenitor cells that have the potential to become, in a context-dependent manner, specific types of cells for regeneration of tissues in brain, spinal cord, and muscle.

Neuroprotective and neurotoxic effects of cyclosporine A on transient focal ischemia in mdr1a knockout mice

The proper dose of cyclosporine A as a neuroprotective agent was investigated using the middle cerebral artery occlusion model of mdr1a knockout mice. After a 30-min occlusion period, reperfusion was performed and the vehicle or cyclosporine A (1 mg/kg or 10 mg/kg x 2) was intraperitoneally administered to each animal model group. Forty eight hours after reperfusion, infarction volume in the 1 mg/kg cyclosporine A group was significantly less than that seen in the vehicle group, although, in the high dose cyclosporine A group, infarction volumes were significantly higher than those seen in the vehicle group. These results demonstrate that cyclosporine A shows not only anti-ischemic effects, but also neurotoxic effects depending on the dosage penetrating into the brain.

Cyclosporine A and adverse effects on organs: histochemical studies

The discovery that cyclosporine A (CsA) was a powerful immunosuppressant had a significant impact on transplant medicine. Its molecular mechanism of action has been well defined in T cells and involved inhibition of critical signalling pathways that regulated T-cell activation. In fact, CsA inhibited calcineurin phosphatase activity and thereby activation of the transcription factor nuclear factor of activated T cells. Over 10 years, its use is limited by side effects, determining nephro- and hepatotoxicity, gingival hypertrophy, tremor and increased blood pressure. These negative effects have been identified through morphological alterations and/or clinical parameters, i.e. variation in glomerular filtration rate for nephrotoxicity. Nevertheless, CsA remains a therapeutic valuable agent and it is normally utilized into clinical practice even if different dose adjustments or discontinuations in a significant percentage of patients must be used. This review focuses on the following topics: mechanisms of action and drug metabolism, interactions with other drugs, clinical and morphological evaluation of toxic effects on target organs. In particular, the morphological evaluation of negative effects has been considered reporting light and ultrastructural studies on target organs both in normal and immunosuppressive conditions. Moreover, the histochemical and immunohistochemical variations in cellular metabolism and antigenic properties of cells present in the parenchyma of these organs are discussed.

AMPA receptors are the major mediators of excitotoxic death in mature oligodendrocytes

Myelination of axons is important for central nervous system function, but oligodendrocytes, which constitute CNS myelin, are vulnerable to excitotoxic injury and death. Although mature oligodendrocytes express functional alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA) and kainate-type glutamate receptors, the relative roles of these subtypes in excitotoxicity are not well understood. Using recently developed selective antagonists for subtypes of ionotropic non-NMDA receptors, we addressed this issue. By examining the pharmacological, biochemical, and morphologic features of kainite-induced excitotoxic death, we also determined whether it occurs by apoptosis, necrosis, or both. We conclude that when mature oligodendrocytes die after exposure to kainate: (1) AMPA receptors are the most important mediators, (2) kainate receptors play a smaller role, and (3) death occurs predominantly by necrosis, not apoptosis.