Association between calcineurin inhibitor treatment and peripheral nerve dysfunction in renal transplant recipients

Tacrolimus-Induced Neurotoxicity After Transplant: A Literature Review

Tacrolimus, a calcineurin inhibitor, is an immunosuppressant used globally to prevent rejection after organ transplantation. Although it significantly improves outcomes for solid organ transplant patients, it is associated with various side effects such as nephrotoxicity and neurotoxicity. Tacrolimus-induced neurotoxicity is frequently encountered in clinical practice and can present with a variety of symptoms that may occur even at therapeutic levels. Although tacrolimus-induced neurotoxicity is well documented, there is limited literature available on pharmacologic management. Twenty-eight case reports of tacrolimus-induced neurotoxicity were identified and analyzed in addition to other literature including reviews, retrospective studies, and animal model studies. The severity of cases of tacrolimus-induced neurotoxicity reported ranged from mild symptoms that could be managed with symptomatic treatment to conditions such as posterior reversible encephalopathy syndrome and chronic inflammatory demyelinating polyradiculoneuropathy that may require more immediate intervention. This information was utilized in addition to clinical experience to compile potential management options for prevention and treatment of neurotoxic adverse events. This review is limited by the utilization of primarily retrospective studies and case reports. The available literature on the subject is largely narrative and there are no guidelines on treatment of tacrolimus-induced neurotoxicity at the time of this research. This comprehensive review may guide further studies to investigate the pathophysiology of tacrolimus-induced neurotoxicity and to define patient-specific strategies for mitigation or minimization of neurotoxicity. This is especially important given that management of tacrolimus-induced neurotoxicity can include changes to immunosuppression that can result in an increased risk of rejection.

An optogenetic cell therapy to restore control of target muscles in an aggressive mouse model of amyotrophic lateral sclerosis

Breakdown of neuromuscular junctions (NMJs) is an early pathological hallmark of amyotrophic lateral sclerosis (ALS) that blocks neuromuscular transmission, leading to muscle weakness, paralysis and, ultimately, premature death. Currently, no therapies exist that can prevent progressive motor neuron degeneration, muscle denervation, or paralysis in ALS. Here, we report important advances in the development of an optogenetic, neural replacement strategy that can effectively restore innervation of severely affected skeletal muscles in the aggressive SOD1G93A mouse model of ALS, thus providing an interface to selectively control the function of targeted muscles using optical stimulation. We also identify a specific approach to confer complete survival of allogeneic replacement motor neurons. Furthermore, we demonstrate that an optical stimulation training paradigm can prevent atrophy of reinnervated muscle fibers and results in a tenfold increase in optically evoked contractile force. Together, these advances pave the way for an assistive therapy that could benefit all ALS patients.

Exosomal miR-181d-5p Derived from Rapamycin-Conditioned MDSC Alleviated Allograft Rejection by Targeting KLF6

Immune rejection and side effects of long-term administration of immunosuppressants are the two major obstacles to allograft acceptance and tolerance. The immunosuppressive extracellular vesicles (EVs)-based approach has been proven to be effective in treating autoimmune/inflammatory disorders. Herein, the anti-rejection advantage of exosomes (Rapa-Exo) from rapamycin-conditioned myeloid-derived suppressor cells (MDSCs) over exosomes (Exo-Nor) from the untreated MDSCs is shown. The exosomal small RNA sequencing and loss-of-function assays reveal that the anti-rejection effect of Rapa-Exo functionally relies on miR-181d-5p. Through target prediction and double-luciferase reporter assay, Kruppel-like factor (KLF) 6 is identified as a direct target of miR-181d-5p. Finally, KLF6 knockdown markedly resolves inflammation and prolongs the survival of corneal allografts. Taken together, these findings support that Rapa-Exo executes an anti-rejection effect, highlighting the immunosuppressive EVs-based treatment as a promising approach in organ transplantation.

Predictors of static and dynamic balance control in kidney transplant recipients

BACKGROUND

We aimed to evaluate balance control and lower extremity muscle strength in kidney transplant recipients (KTRs) including a comparison to a healthy control group and determine the predictors of static and dynamic balance control after kidney transplantation.

METHODS

In this study 40 KTRs and 40 healthy controls were included. Balance control was assessed using the Biodex balance system. The static postural stability test (SPST) and clinical test of sensory integration and balance (CTSIB) were used to assess static balance control whereas the dynamic postural stability test (DPST) and limits of stability test (LOST) were used for dynamic balance control. Lower extremity muscle strength was measured with a hand-held dynamometer. Renal functions and laboratory findings of KTRs were recorded.

RESULTS

All the stability index scores of SPST and sway index in CTSIB were significantly higher in KTRs compared to healthy controls. The right anteroposterior stability index score in DPST and the reaction time in LOST were significantly higher whereas overall score in LOST and lower extremity muscle strength were significantly lower in KTRs. The linear regression analysis revealed that hemoglobin was the predictor of static balance control accounting for 11% of the variance and body weight was the predictor of dynamic balance control accounting for 34% of the variance.

CONCLUSION

Balance control, both static and dynamic, are impaired in KTRs as well as lower extremity muscle strength. Hemoglobin level is a predictor of static balance control whereas body weight is a predictor of dynamic balance control after kidney transplantation.

Long-term effects of pancreatic islet transplantation on polyneuropathy in patients with brittle diabetes: A single-center experience

INTRODUCTION/AIMS

Pancreatic islet transplantation (ITx) is increasingly used in patients with brittle type 1 diabetes (T1D). If successful, ITx results in insulin-free euglycemia, but its application is limited by a need for lifelong immunosuppression. The aim of this study was to assess the long-term effects of ITx on the occurrence and course of polyneuropathy in a cohort of patients with brittle T1D.

METHODS

In this prospective, single-center study, 13 patients (4 males and 9 females) with brittle T1D had a baseline neurological exam with the calculation of Utah Neuropathy Scale (UNS) and a limited nerve conduction study before ITx, and about yearly after in the patients who achieved insulin independence.

RESULTS

Patients were followed for a period of 17 to 133 months. There was no significant difference between UNS and nerve conduction study parameters at baseline and at the end of follow-up, except for significant decreases in peroneal (50.34 ± 6.12 vs. 52.42 ± 6.47 ms, P = 0.005) and ulnar (27.5 ± 2.15 vs. 29.45 ± 2.10 ms, P = 0.009) F-wave latencies and an increase in ulnar sensory nerve conduction velocity (49.98 ± 6.27 vs. 47.19 ± 5.36 m/s, P = 0.04).

DISCUSSION

If successful, ITx has a good long-term safety profile for peripheral nerve toxicity, and a favorable effect on diabetic neuropathy.

Toxic neuropathies: a practical approach

Toxic neuropathies result from exogenous substances damaging the peripheral nerves. There are numerous causes, including prescribed and recreational drugs, heavy metals, industrial agents and biological toxins. Timely recognition of these neuropathies gives better outcomes, as they usually improve or stabilise once the toxin is removed. Most toxic neuropathies are axonal, length-dependent and sensory predominant, although some have significant motor involvement or can present acutely or subacutely. Here, we outline our clinical approach and discuss the major causes of toxic neuropathy, while emphasising the clinical and neurophysiological features and the neuropathy phenotype. We also include an update on newer medications that can cause neuropathy, including immune checkpoint inhibitors and BRAF/MEK inhibitors.

PASC in Solid Organ Transplant Recipients With Self-reported SARS-CoV-2 Infection

BACKGROUND

Postacute sequelae of SARS-CoV-2 infection (PASC) is an increasingly recognized phenomenon and manifested by long-lasting cognitive, mental, and physical symptoms beyond the acute infection period. We aimed to estimate the frequency of PASC symptoms in solid organ transplant (SOT) recipients and compared their frequency between those with SARS-CoV-2 infection requiring hospitalization and those who did not require hospitalization.

METHODS

A survey consisting of 7 standardized questionnaires was administered to 111 SOT recipients with history of SARS-CoV-2 infection diagnosed >4 wk before survey administration.

RESULTS

Median (interquartile range) time from SARS-CoV-2 diagnosis was 167 d (138-221). Hospitalization for SARS-CoV-2 infection was reported in 33 (30%) participants. Symptoms after the COVID episode were perceived as following: significant trauma (53%), cognitive decline (50%), fatigue (41%), depression (36%), breathing problems (35%), anxiety (23%), dysgeusia (22%), dysosmia (21%), and pain (19%). Hospitalized patients had poorer median scores in cognition (Quick Dementia Rating System survey score: 2.0 versus 0.5, P = 0.02), quality of life (Health-related Quality of Life survey: 2.0 versus 1.0, P = 0.015), physical health (Global physical health scale: 10.0 versus 11.0, P = 0.005), respiratory status (Breathlessness, Cough and Sputum Scale: 1.0 versus 0.0, P = 0.035), and pain (Pain score: 3 versus 0 out of 10, P = 0.003). Among patients with infection >6 mo prior, some symptoms were still present as following: abnormal breathing (42%), cough (40%), dysosmia (29%), and dysgeusia (34%).

CONCLUSIONS

SOT recipients reported a high frequency of PASC symptoms. Multidisciplinary approach is needed to care for these patients beyond the acute phase.

Engineered immunomodulatory accessory cells improve experimental allogeneic islet transplantation without immunosuppression

Islet transplantation has been established as a viable treatment modality for type 1 diabetes. However, the side effects of the systemic immunosuppression required for patients often outweigh its benefits. Here, we engineer programmed death ligand-1 and cytotoxic T lymphocyte antigen 4 immunoglobulin fusion protein-modified mesenchymal stromal cells (MSCs) as accessory cells for islet cotransplantation. The engineered MSCs (eMSCs) improved the outcome of both syngeneic and allogeneic islet transplantation in diabetic mice and resulted in allograft survival for up to 100 days without any systemic immunosuppression. Immunophenotyping revealed reduced infiltration of CD4+ or CD8+ T effector cells and increased infiltration of T regulatory cells within the allografts cotransplanted with eMSCs compared to controls. The results suggest that the eMSCs can induce local immunomodulation and may be applicable in clinical islet transplantation to reduce or minimize the need of systemic immunosuppression and ameliorate its negative impact.

Clinical and neurophysiological characterization of early neuromuscular involvement in children and adolescents with nephropathic cystinosis

BACKGROUND

Nephropathic cystinosis is a rare autosomal recessive lysosomal storage disorder characterized by kidney and extra-renal complications due to the accumulation of cystine crystals in various tissues and organs. Herein, we describe the early neuromuscular complications in a cohort of pediatric nephropathic cystinosis patients.

METHODS

We prospectively evaluated the clinical, biochemical, and neurophysiological data of 15 cystinosis patients. Neurophysiological evaluation was performed to confirm or exclude presence of neuropathy and/or myopathy.

RESULTS

Patients' age ranged between 20 and 216 months at time of examination. Nine patients were males. Three patients had early abnormal neurophysiological features consistent with neuromuscular involvement (clinically asymptomatic proximal myopathy with a patchy distribution in one patient and isolated asymptomatic sensory nerve conduction changes in two patients). A fourth patient had mixed abnormal motor and sensory axonal neuropathic changes associated with overt clinical features (predominantly motor symptoms). Patients with abnormal neuromuscular features were significantly older in age than the unaffected group (P = 0.005) and had a diagnosis of cystinosis with subsequent cysteamine therapy at a significantly older age than the unaffected group (P = 0.027 and 0.001, respectively).

CONCLUSIONS

We expanded the recognized phenotypes of cystinosis neuromuscular complications with early proximal skeletal myopathy and symptomatic motor and sensory axonal neuropathy. Early asymptomatic neuromuscular complications could develop in pediatric patients and would require neurophysiological studies for early detection prior to development of overt clinical manifestations. Prompt diagnosis and timely initiation of cysteamine therapy with recommended dose can delay the development of neuromuscular complications. A higher resolution version of the Graphical abstract is available as Supplementary information.

A Comprehensive Review of Calcineurin Inhibitors Used for Immunosuppression in Cardiac Transplantation

Calcineurin inhibitors (CNIs) have been the foundation of immunosuppression in solid organ transplantation since the 1980s. Cyclosporine A (CSA), the first in class, was identified as the metabolite of the soil fungus Tolypocladium inflatum Gams as part of a larger program of screening for naturally occurring fungal metabolites with biologic activity in the 1970s. Significant immunosuppressive effects were discovered and consequently CSA was trialed as an immunosuppressant in renal transplantation. This initial success led to its widespread study and adoption in solid organ transplantation. This novel agent yielded significant improvements in both 1 year and longer-term allograft and patient survival. Subsequently, a similar and more potent CNI, tacrolimus was developed. Today, it is the principal CNI used for prevention of allograft rejection. Like all other immunosuppressives, the benefits of CNIs are counterbalanced by side effects and complications resulting from drug toxicity. This chapter comprehensively reviews the clinical use of CNIs in cardiac transplantation.

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.

Effects of islet transplantation on microvascular and macrovascular complications in type 1 diabetes

Type 1 diabetes is associated with high morbidity and mortality from microvascular and macrovascular disease with considerable economic cost to society. Islet cell transplantation (ICT) is a treatment option recommended by National Institute for Health and Care Excellence (NICE) for people with debilitating hypoglycaemia due to type 1 diabetes, including those with renal failure where kidney transplantation may also be indicated. The primary aim of ICT is to improve glycaemic control, reduce severe hypoglycaemia, stabilise glycaemic variability and restore awareness of hypoglycaemia where this is compromised. Insulin independence, although not a primary aim, should also be considered a therapeutic goal. The impact ICT has on the progression of microvascular and macrovascular diabetes complications is derived from small studies and has not been examined in large clinical trials. Lifelong immunosuppression, which is necessary to avoid transplant rejection, has adverse effects on lipid metabolism, hypertension and renal function, which must also be considered. In this review, we discuss the role of ICT in type 1 diabetes management and the available evidence with respect to microvascular and macrovascular disease progression post-transplantation. We conclude that, following ICT, microvascular complications including retinopathy and neuropathy are stabilised or improved. Effects on nephropathy can be complicated by coexisting kidney transplantation and the impact of immunosuppression, the latter leading to an early decline in renal function; however, there is evidence to suggest stable renal outcomes in the long term. Short-term studies have demonstrated a positive impact of ICT on surrogate markers of macrovascular disease; however, long-term studies and trials in this area are lacking.

No evidence of improvement in neuropathy after renal transplantation in patients with end stage kidney disease

To assess the impact of renal transplantation on peripheral nerve damage in patients with chronic kidney disease (CKD). Fifteen patients with CKD (eGFR <15 mL/min/1.73 m² ) underwent longitudinal assessment after renal transplantation (age: 56.88 ± 2.53 years, eGFR: 46.82 ± 4.86) and were compared with 15 age-matched controls (age: 58.25 ± 2.18 years, eGFR: 86.0 ± 2.0). The neuropathy symptom profile (NSP), neuropathy disability score (NDS), vibration perception threshold (VPT), cold and warm sensation threshold (CST and WST), cold and heat induced pain (CIP and HIP), deep breathing heart rate variability (DB-HRV), nerve conduction studies and corneal confocal microscopy (CCM) to quantify small nerve fibre pathology, were undertaken within 1-month of renal transplantation (baseline) and at 6, 12 and 24 months of follow up. There was no significant difference in NSP (P = .1), NDS (P = .3), VPT (P = .6), CST (P = .2), CIP (P = .08), HIP (P = .1), DB-HRV (P = .9) and sural (P = .4) and peroneal (P = .1) nerve amplitude between patients with CKD and controls at baseline. However, sural (P = .04), peroneal (P = .002) and tibial (P = .007) nerve conduction velocity and tibial nerve amplitude (P = .03) were significantly lower, WST (P = .02) was significantly higher and corneal nerve fibre density (P = .004) was significantly lower in patients with CKD compared with controls. There was no significant change in NSP, NDS, quantitative sensory testing, DB-HRV, nerve conduction or CCM parameters 24 months after renal transplantation. There is evidence of small and large fibre neuropathy in patients with CKD, but no change up to 24 months after successful renal transplantation.

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.

A Review of Acute and Long-Term Neurological Complications Following Haematopoietic Stem Cell Transplant for Paediatric Acute Lymphoblastic Leukaemia

Despite advances in haematopoietic stem cell transplant (HSCT) techniques, the risk of serious side effects and complications still exists. Neurological complications, both acute and long term, are common following HSCT and contribute to significant morbidity and mortality. The aetiology of neurotoxicity includes infections and a wide variety of non-infectious causes such as drug toxicities, metabolic abnormalities, irradiation, vascular and immunologic events and the leukaemia itself. The majority of the literature on this subject is focussed on adults. The impact of the combination of neurotoxic drugs given before and during HSCT, radiotherapy and neurological complications on the developing and vulnerable paediatric and adolescent brain remains unclear. Moreover, the age-related sensitivity of the nervous system to toxic insults is still being investigated. In this article, we review current evidence regarding neurotoxicity following HSCT for acute lymphoblastic leukaemia in childhood. We focus on acute and long-term impacts. Understanding the aetiology and long-term sequelae of neurological complications in children is particularly important in the current era of immunotherapy for acute lymphoblastic leukaemia (such as chimeric antigen receptor T cells and bi-specific T-cell engager antibodies), which have well-known and common neurological side effects and may represent a future treatment modality for at least a fraction of HSCT-recipients.

Neurologic Toxicities Associated with Tumor Necrosis Factor Inhibitors and Calcineurin Inhibitors

The calcineurin inhibitors cyclosporine and tacrolimus are used for their immunosuppressive effects. Neurotoxic side effects include tremor, paresthesia, and headache. Rarer neurotoxicities include seizure, posterior reversible encephalopathy syndrome, and encephalopathy. Tacrolimus tends to be more neurotoxic than cyclosporine. Management of toxicities associated with calcineurin inhibitors includes dose reduction, switching between calcineurin inhibitors, or switching to a calcineurin-free regimen. Tumor necrosis factor (TNF) inhibitors are used in autoimmune diseases. Management of demyelinating conditions among patients treated with anti-TNF should follow standard of care and withdrawal of the anti-TNF. This drug class should be avoided in patients with a history of demyelinating conditions.

Immunotherapy via PD-L1-presenting biomaterials leads to long-term islet graft survival

Antibody-mediated immune checkpoint blockade is a transformative immunotherapy for cancer. These same mechanisms can be repurposed for the control of destructive alloreactive immune responses in the transplantation setting. Here, we implement a synthetic biomaterial platform for the local delivery of a chimeric streptavidin/programmed cell death-1 (SA-PD-L1) protein to direct "reprogramming" of local immune responses to transplanted pancreatic islets. Controlled presentation of SA-PD-L1 on the surface of poly(ethylene glycol) microgels improves local retention of the immunomodulatory agent over 3 weeks in vivo. Furthermore, local induction of allograft acceptance is achieved in a murine model of diabetes only when receiving the SA-PD-L1-presenting biomaterial in combination with a brief rapamycin treatment. Immune characterization revealed an increase in T regulatory and anergic cells after SA-PD-L1-microgel delivery, which was distinct from naïve and biomaterial alone microenvironments. Engineering the local microenvironment via biomaterial delivery of checkpoint proteins has the potential to advance cell-based therapies, avoiding the need for systemic chronic immunosuppression.

The Effect of Maintenance Treatment with Twice-Daily or Prolonged Once-Daily Tacrolimus Formulation on Visual Evoked Potentials in Stable Kidney Transplant Recipients

In kidney transplant recipients (KTRs), uraemia-induced central nervous system damage partly subsides, while the long-lasting exposure to tacrolimus may cause pathologic visual evoked potentials (VEP) findings, which have not been investigated yet. Thus, the aim of the present study was to assess the effect of tacrolimus maintenance treatment on bioelectrical function of optic nerves in stable KTRs. Sixty-five stable KTRs were enrolled, including 30 patients treated with twice-daily (Prograf) and 35 patients treated with prolonged once-daily (Advagraf) tacrolimus formulation. In all patients, pattern and flash VEP measurements were performed. Tacrolimus dosing and exposure were also analyzed. Overall, 129 eyes were analyzed. In pattern VEP, both (1°) and (15') latencies of P100 waves were significantly longer, whereas (1°) and (15') amplitudes were lower in the Advagraf group as compared with the Prograf group. Multivariate regression analyses revealed that the use of Advagraf (vs. Prograf) was independently associated with longer (1°) and (15') P100 latencies and lower corresponding amplitudes, whereas log tacrolimus daily dose was only related to amplitudes in a whole study group. In flash VEP, log tacrolimus trough level was associated with negative changes in P2 wave amplitude irrespective of tacrolimus formulation, whereas its association with P2 latency was observed only in the Prograf group. Both the type of tacrolimus formulation and drug exposure influenced the VEP parameters in stable KTRs.

Long-term small-fiber neuropathy and pain sensitization in survivors of pediatric acute lymphoblastic leukemia after stem cell transplantation

PURPOSE

We aimed at describing for the first time peripheral small-fiber neurotoxicity and pain sensitization in survivors of pediatric acute lymphoblastic leukemia after stem cell transplantation (SCT).

METHODS

In a cross-sectional, retrospective, single-center study, we assessed 25 relapse-free long-term survivors (median age at SCT: 11 ± 4.9 years; median time between SCT and testing: 8.25 years, 19 males) using a reduced version of the pediatric-modified total neuropathy score for clinical assessment and Quantitative Sensory Testing (QST).

INCLUSION CRITERIA

[Formula: see text] 6 years old at testing, [Formula: see text] 18 years old at time of SCT, [Formula: see text] 1 year between SCT and testing.

RESULTS

Nine patients (36%) had peripheral neuropathy as defined by the clinical red-pmTNS (≥ 4). The QST parameters mechanical pain sensitivity, mechanical detection threshold, thermal sensory limen, vibration detection threshold and pressure pain threshold were significantly abnormal in the survivor cohort (p < 0.0038). Except for one, all survivors showed at least one abnormal QST parameter. When using QST, signs of small and large fiber dysfunction were present in 22 (88%) and 17 (68%) survivors, respectively. More than half of all survivors were found to experience pathologic sensitization to pain.

CONCLUSIONS AND IMPLICATIONS FOR CANCER SURVIVORS

Survivors of pediatric acute lymphoblastic leukemia after SCT are at high risk for long-term peripheral neuropathy with a dominating small-fiber and pain sensitization pattern.

Potassium control in chronic kidney disease: implications for neuromuscular function

In Australia, approximately 1.7 million adults have evidence of chronic kidney disease (CKD). This complex disease can result in a multitude of complications, including hyperkalaemia, which is common and well recognised. The advent of new therapeutics aimed at lowering serum potassium has raised the possibility of optimising potassium control to enable greater use of renin-angiotensin-aldosterone system inhibitors in the management of CKD. Recent studies suggest that hyperkalaemia also has implications for peripheral neuropathy in CKD, a complication that substantially contributes to patient morbidity. This review examines evidence of the relationship between potassium and peripheral neuropathy, with a discussion of clinical implications. We searched PubMed for original and review articles using pre-specified key words, clinical guidelines and population data. The major findings were that contemporary CKD cohorts demonstrate a high prevalence of peripheral neuropathy, even in stage 3-4 CKD, including those without diabetes. The severity of the problem has been emphasised by an ominous rise in foot complications and amputation rates in dialysis patients, highlighting the need for increased awareness of the condition in earlier stages of CKD and targeted treatment strategies. It is likely that the pathophysiology of peripheral neuropathy in CKD is multifaceted, with potential influences from potassium, vascular abnormalities, diabetes, inflammation and unknown middle molecules. Despite these complexities, the relationship between potassium and nerve function in dialysis has been well established, and recent research in stage 3-4 CKD suggests that assertive potassium control may improve neuromuscular outcomes in CKD. These small studies should be confirmed in large, multicentre settings.

Effect of Kidney Transplant on Balance and Fall Risk

OBJECTIVES

Kidney transplant offers an improved quality of life and prolonged survival for patients with end-stage renal disease. This study aimed to compare balance and fall risk between kidney transplant recipients and healthy adults and to determine the relationship between biochemical parameters and fall risk and balance in kidney transplant recipients. As far as we know, this is the first study in the literature that evaluated whether balance changes occur in kidney transplant recipients using the Tetrax Interactive Balance System (Sunlight Medical Ltd., Ramat Gan, Israel).

MATERIALS AND METHODS

Our study included 131 kidney transplant recipients (80 male/53 female; mean age of 39 ± 12 y) and 158 healthy volunteers (86 male/69 female; mean age of 40 ± 15 y). Groups were statistically matched in age, male/female patients, and body mass index. Fall index percentages were calculated using the Tetrax posturography device. Risk of falling was compared between kidney transplant recipients and healthy participants. Kidney transplant recipients were divided into 3 groups based on risk of falling. Demographic and clinical characteristics of kidney transplant recipients were recorded, and statistical analyses were performed to analyze these parameters versus balance measurements.

RESULTS

Risk of falling was not significantly different between groups according to Tetrax measurements (32.4 ± 23.4 vs 31.6 ± 21.7; P = .08). Serum creatinine levels were significantly higher in kidney transplant recipients with a higher risk of falling (1.17 ± 0.37 vs 1.63 ± 1.18 mg/dL; P = .01). The use of oral antidiabetic drugs was shown to increase the risk of falling (P = .02).

CONCLUSIONS

Although patients with end-stage renal disease are thought to have balance impairments, kidney transplant recipients in our study had balance control similar to that shown in the healthy population. Graft function in kidney transplant recipients is important for the balance system.

Postural balance, muscle strength, and history of falls in end-stage renal disease patients living with a kidney transplant: A cross-sectional study

BACKGROUND

End-stage renal disease patients living with a kidney transplant (KT) often present with frailty, functional disability, and mobility impairments that may result in a high risk of falls. Postural balance and muscle strength are implicated in the etiology of falls in the geriatric population, and both may be impaired in KT patients.

RESEARCH QUESTION

We conducted a cross-sectional investigation to estimate the prevalence of falls, as well as to explore the association between postural balance, muscle strength and history of falls in end-stage renal disease patients living with a KT.

METHODS

Fifty-nine prevalent KT patients (age = 53.2 ± 11 years) were enrolled in this cross-sectional study. Participants were classified as fallers/non-fallers and underwent an objectively-measured assessment of postural balance on a stabilometric platform in eyes open (EO), eyes closed (EC), and dual-task (DT) conditions. Center of pressure (CoP) variables were taken for the analysis. In addition, participants underwent isometric (IM) and isokinetic (IK) assessments of lower limb muscle strength on a multi-joint evaluation system.

RESULTS

Thirty-four percent of the study participants reported at least one fall in the previous 12 months. In logistic regression analysis, CoP velocity in EO (OR: 1.23, 95 % CI: 1.06-1.43, p = .007), and IK ankle dorsiflexion strength (OR: 0.87, 95 % CI: 0.77-0.99, p = .034) were independently associated with increased odds of falling.

SIGNIFICANCE

This cross-sectional study indicates that patients living with a KT presented with a prevalence of falls indicative of a high risk of falling. Postural balance and muscle strength are exercise-modifiable factors and further research is warranted to establish to what extent these measures may be implicated in the etiology of falling in this patient group.

Chronic kidney disease and peripheral nerve function in the Health, Aging and Body Composition Study

BACKGROUND

Chronic kidney disease (CKD) is associated with poor mobility. Peripheral nerve function alterations play a significant role in low mobility. We tested the hypothesis that early CKD is associated with altered sensory, motor and autonomic nerve function.

METHODS

Participants in the Health, Aging and Body Composition cohort who had kidney function measures in Year 3 (1999-2000) and nerve function measurements at Year 4 (2000-01) were analyzed (n = 2290). Sensory (vibration threshold, monofilament insensitivity to light and standard touch), motor [compound motor action potentials (CMAPs), nerve conduction velocities (NCVs)] and autonomic (heart rate response and recovery after a 400-m walk test) nerve function as well as participant characteristics were compared across cystatin C- and creatinine-based estimated glomerular filtration rate categorized as ≤60 (CKD) or >60 mL/min/1.73 m2 (non-CKD). The association between CKD and nerve function was examined with logistic regression adjusted for covariates.

RESULTS

Participants with CKD (n = 476) were older (77 ± 3 versus 75 ± 3 years; P < 0.05) and had a higher prevalence of diabetes (20.6% versus 13.1%; P < 0.001). CKD was associated with higher odds for vibration detection threshold {odds ratio [OR] 1.7 [95% confidence interval (CI) 1.1-2.7]} and light touch insensitivity [OR 1.4 (95% CI 1.1-1.7)]. CMAPs and NCVs were not significantly different between CKD and non-CKD patients. In adjusted analyses, participants with CKD had higher odds of an abnormal heart rate response [OR 1.6 (95% CI 1.1-2.2)] and poor heart rate recovery [OR 1.5 (95% CI 1.1-2.0)].

CONCLUSIONS

CKD is associated with changes in sensory and autonomic nerve function, even after adjustment for demographics and comorbidities, including diabetes. Longitudinal studies in CKD are needed to determine the contribution of nerve impairments to clinically important outcomes.

Simultaneous Pancreas Kidney Transplantation Improves Cardiovascular Autonomic Neuropathy with Improved Valsalva Ratio as the Most Precocious Test

BACKGROUND

Simultaneous pancreas-kidney (SPK) transplantation is a proven option of treatment for patients with type 1 diabetes mellitus (T1DM) and related end-stage renal disease. There is discrepancy between the results of different studies about the impact of prolonged normalization of glucose metabolism achieved by SPK on the course of diabetic complications including severe forms of diabetic neuropathy. The objective of the study was to evaluate the prevalence of cardiovascular autonomic neuropathy (CAN) in patients undergoing SPK transplantation and its evolution 10 years after transplantation.

METHODS

Prospective study of 81 patients transplanted in a single center from year 2002 to 2015. Autonomic function was assessed using cardiovascular autonomic reflex tests (CARTs). CARTs were made before SPK transplantation and during the follow-up. Evolution of tests after SPK transplantation was evaluated by contrasting hypotheses (paired tests). Multiple testing was adjusted with the Benjamini-Hochberg procedure with a false discovery rate of 10%.

RESULTS

48 males and 33 females, mean age 37.4 ± 5.7 years, mean BMI 24.0 ± 3.4 kg/m², and mean duration of diabetes 25.5 ± 6.5 years, received SPK transplantation. Ten years after SPK transplantation, 56 patients re tained the pancreatic graft (42 of them with normofunctioning pancreas and 14 with low doses of insulin therapy). These 42 patients were selected for the autonomic study. Before transplant procedure, all CART results were abnormal. After SPK transplantation, paired test analysis showed an improvement of systolic blood pressure (SBP) response to orthostasis at the 5^th year after SPK (p = 0.03), as well as improvement of the Valsalva ratio at the 3^rd (p < 0.001) and 5^th (p = 0.001) year after SPK. After correcting for the false discovery rate, all the variables of autonomic study reached significance at different time points.

CONCLUSIONS

Prevalence of CAN in patients who are candidates for SPK transplantation is high and is generally advanced. SPK transplantation improves CAN with improved Valsalva ratio as the most precocious test.

Measurement of axonal excitability: Consensus guidelines

Measurement of axonal excitability provides an in vivo indication of the properties of the nerve membrane and of the ion channels expressed on these axons. Axonal excitability techniques have been utilised to investigate the pathophysiological mechanisms underlying neurological diseases. This document presents guidelines derived for such studies, based on a consensus of international experts, and highlights the potential difficulties when interpreting abnormalities in diseased axons. The present manuscript provides a state-of-the-art review of the findings of axonal excitability studies and their interpretation, in addition to suggesting guidelines for the optimal performance of excitability studies.

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.

Neurologic complications of kidney transplantation

Renal transplant is the most common organ transplant in the United States, and the frequency of kidney transplants continues to rise as transplant offers improved survival and quality of life compared to dialysis. However, complications are not uncommon and patients frequently encounter issues requiring hospitalization, especially in the first year postoperatively. Complications that arise are typically related to surgical complications, immunosuppressive medications, or infection due to immunosuppression. Neurological complications are fairly common post-operatively, and are associated with increased morbidity and mortality in this population. This review discusses the most common etiologies of neurological complications after kidney transplant, including infection, malignancy, medication related, acute neuropathy, and other neurological pathology.

Randomised controlled trial of the impact of haemodiafiltration on uraemic neuropathy: FINESSE study protocol

INTRODUCTION

The majority of patients undergoing haemodialysis (HD) show evidence of uraemic neuropathy, a condition with no known disease-modifying treatments. The pathogenesis of uraemic neuropathy is poorly understood, but may be related to cumulative exposure to middle molecules or other solutes such as potassium. It is not known whether haemodiafiltration (HDF) reduces the progression of uraemic neuropathy.

METHODS AND ANALYSIS

Filtration In the Neuropathy of End-Stage kidney disease Symptom Evolution (FINESSE) is a multicentre, randomised, open-label, blinded endpoint assessment, controlled trial designed to assess the impact of HDF versus HD on uraemic neuropathy. Maintenance HD patients will be randomised in a 1:1 ratio to receive HDF or HD with high-flux membranes for 4 years. The primary endpoint is the difference in the mean change in Total Neuropathy Score (TNS)-a measure of peripheral neuropathy combining symptoms, signs and nerve conduction velocity-over the study period. Secondary outcomes include change at annual timepoints in the TNS and the Neuropathy Symptom Score; and in morbidity, mortality and safety events.

ETHICS AND DISSEMINATION

The FINESSE trial has been approved by the Ethics Review Committee of the Sydney South West Area Health Service (HREC/09/RPAH/268) and of Adventist HealthCare Limited (2012-027). When published in a peer-reviewed journal, it will be the largest and longest reported randomised trial aimed at reducing the incidence and severity of uraemic neuropathy. It will advance the understanding of the natural history of uraemic neuropathy and the influence of convective therapies on both neurophysiological and clinical outcomes. It will also allow refinement of current hypotheses surrounding the pathogenesis of uraemic neuropathy and, most importantly, may lead to improvements in the lives of the many patients affected by this debilitating condition.

TRIAL REGISTRATION NUMBER

ACTRN12609000615280.

Rationale and design of TransplantLines: a prospective cohort study and biobank of solid organ transplant recipients

INTRODUCTION

In the past decades, short-term results after solid organ transplantation have markedly improved. Disappointingly, this has not been accompanied by parallel improvements in long-term outcomes after transplantation. To improve graft and recipient outcomes, identification of potentially modifiable risk factors and development of biomarkers are required. We provide the rationale and design of a large prospective cohort study of solid organ transplant recipients (TransplantLines).

METHODS AND ANALYSIS

TransplantLines is designed as a single-centre, prospective cohort study and biobank including all different types of solid organ transplant recipients as well as living organ donors. Data will be collected from transplant candidates before transplantation, during transplantation, at 3 months, 6 months, 1 year, 2 years and 5 years, and subsequently every 5 years after transplantation. Data from living organ donors will be collected before donation, during donation, at 3 months, 1 year and 5 years after donation, and subsequently every 5 years. The primary outcomes are mortality and graft failure. The secondary outcomes will be cause-specific mortality, cause-specific graft failure and rejection. The tertiary outcomes will be other health problems, including diabetes, obesity, hypertension, hypercholesterolaemia and cardiovascular disease, and disturbances that relate to quality of life, that is, physical and psychological functioning, including quality of sleep, and neurological problems such as tremor and polyneuropathy.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the relevant local ethics committee. The TransplantLines cohort study is designed to deliver pioneering insights into transplantation and donation outcomes. The study design allows comprehensive data collection on perioperative care, nutrition, social and psychological functioning, and biochemical parameters. This may provide a rationale for future intervention strategies to more individualised, patient-centred transplant care and individualisation of treatment.

TRIAL REGISTRATION NUMBER

NCT03272841.

In Vivo Electrophysiological Measurement of the Rat Ulnar Nerve with Axonal Excitability Testing

Electrophysiology enables the objective assessment of peripheral nerve function in vivo. Traditional nerve conduction measures such as amplitude and latency detect chronic axon loss and demyelination, respectively. Axonal excitability techniques "by threshold tracking" expand upon these measures by providing information regarding the activity of ion channels, pumps and exchangers that relate to acute function and may precede degenerative events. As such, the use of axonal excitability in animal models of neurological disorders may provide a useful in vivo measure to assess novel therapeutic interventions. Here we describe an experimental setup for multiple measures of motor axonal excitability techniques in the rat ulnar nerve. The animals are anesthetized with isoflurane and carefully monitored to ensure constant and adequate depth of anesthesia. Body temperature, respiration rate, heart rate and saturation of oxygen in the blood are continuously monitored. Axonal excitability studies are performed using percutaneous stimulation of the ulnar nerve and recording from the hypothenar muscles of the forelimb paw. With correct electrode placement, a clear compound muscle action potential that increases in amplitude with increasing stimulus intensity is recorded. An automated program is then utilized to deliver a series of electrical pulses which generate 5 specific excitability measures in the following sequence: stimulus response behavior, strength duration time constant, threshold electrotonus, current-threshold relationship and the recovery cycle. Data presented here indicate that these measures are repeatable and show similarity between left and right ulnar nerves when assessed on the same day. A limitation of these techniques in this setting is the effect of dose and time under anesthesia. Careful monitoring and recording of these variables should be undertaken for consideration at the time of analysis.

Long-term diabetes complications after pancreas transplantation

PURPOSE OF REVIEW

The intention of this study is to summarize present knowledge about adverse effects of hyperglycemia in diabetes, and in this context review more recent data concerning the effects of pancreas transplantation on a wide range of diabetic complications.

RECENT FINDINGS

Effective blood glucose control by insulin delays progression of microvascular complications and probably improves survival in type 1 diabetes. A successful pancreas transplantation combined with a kidney graft has recently been found to prevent diabetic kidney lesions, and registry data support improved long-term patient survival. Cardiovascular mortality was reduced in one study, even though coronary heart disease was not significantly altered. Advanced coronary lesions may be too advanced in these patients at baseline. However, with a successful single pancreas transplant, which is generally performed in patients with near-normal kidney function, pancreas transplantation may improve left ventricular function. Development of retinopathy and neuropathy is delayed with functioning pancreas grafts, and both quality of life and certain skin lesions may improve after pancreas transplantation.

SUMMARY

In patients with type 1 diabetes, pancreas transplantation may improve cardiac outcomes and ameliorate diabetic lesions in the kidney transplant. Also quality of life, neuropathy, retinopathy, and healing of certain skin lesions may be improved.

Neurological complications of renal dialysis and transplantation

Neurological complications from renal replacement therapy contribute significantly to morbidity and mortality in patients with renal failure. Such complications can affect either the central or peripheral nervous systems. Most neurological disturbances associated with the uraemic state do not respond fully to renal replacement therapy. There are also complications specifically associated with dialysis and transplantation. A multidisciplinary approach, involving both nephrologists and neurologists, is critical for the diagnosis and effective management of these disorders.

An Elastomeric Polymer Matrix, PEUU-Tac, Delivers Bioactive Tacrolimus Transdurally to the CNS in Rat

Central nervous system (CNS) neurons fail to regrow injured axons, often resulting in permanently lost neurologic function. Tacrolimus is an FDA-approved immunosuppressive drug with known neuroprotective and neuroregenerative properties in the CNS. However, tacrolimus is typically administered systemically and blood levels required to effectively treat CNS injuries can lead to lethal, off-target organ toxicity. Thus, delivering tacrolimus locally to CNS tissues may provide therapeutic control over tacrolimus levels in CNS tissues while minimizing off-target toxicity. Herein we show an electrospun poly(ester urethane) urea and tacrolimus elastomeric matrix (PEUU-Tac) can deliver tacrolimus trans-durally to CNS tissues. In an acute CNS ischemia model in rat, the optic nerve (ON) was clamped for 10s and then PEUU-Tac was used as an ON wrap and sutured around the injury site. Tacrolimus was detected in PEUU-Tac wrapped ONs at 24 h and 14 days, without significant increases in tacrolimus blood levels. Similar to systemically administered tacrolimus, PEUU-Tac locally decreased glial fibrillary acidic protein (GFAP) at the injury site and increased growth associated protein-43 (GAP-43) expression in ischemic ONs from the globe to the chiasm, consistent with decreased astrogliosis and increased retinal ganglion cell (RGC) axon growth signaling pathways. These initial results suggest PEUU-Tac is a biocompatible elastic matrix that delivers bioactive tacrolimus trans-durally to CNS tissues without significantly increasing tacrolimus blood levels and off-target toxicity.

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PEUU-Tac locally delivers tacrolimus to CNS tissues

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PEUU-Tac positively modulates CNS tissue remodeling

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PEUU-Tac minimizes off-target tacrolimus toxicity

Central nervous system (CNS) injury typically results in permanently lost neurological function. Tacrolimus is an FDA-approved drug used during organ transplantation that also has CNS neuroprotective and neuroregenerative properties. However, tacrolimus is typically delivered systemically in the blood and delivering effective concentrations to CNS tissues requires tacrolimus blood levels that can lead to adverse side effects in multiple organs. Herein we show that PEUU-Tac, a tacrolimus-eluting matrix, can locally deliver tacrolimus to injured CNS tissues without increasing blood levels, suggesting PEUU-Tac can be used to treat CNS injuries locally while minimizing adverse side effects.

Transfusion-acquired hepatitis E infection misdiagnosed as severe critical illness polyneuromyopathy in a heart transplant patient

This is the case of a 56-year-old man who underwent heart transplantation. Within the first postoperative days, his respiratory and limb muscles weakened, which was attributed to critical illness polyneuromyopathy (CIPM). At day 70 post transplantation, he had increased liver enzyme levels and acute hepatitis E virus (HEV) infection was diagnosed. HEV RNA was found in the serum, stools, and cerebrospinal fluid. Results of further investigations suggested a possible HEV-related polyradiculoneuropathy. At transplantation, the patient was negative for immunoglobulin (Ig)G, IgM, and HEV RNA. A trace-back procedure identified the source of infection and concluded that HEV infection was contracted from blood transfusion 12 days prior to transplantation from an HEV RNA-positive donor. Tests of the organ donor for HEV were negative. Phylogenetic analysis revealed sequence homology between the HEV-3 strain of the patient and the HEV-3 strain of the blood donor. Despite ribavirin treatment, the patient died on day 153 post transplantation from multiorgan failure. In conclusion, patients with hepatitis or neuropathic illness who have received blood products should be screened for HEV.

Randomized, Controlled Trial of the Effect of Dietary Potassium Restriction on Nerve Function in CKD

BACKGROUND AND OBJECTIVES

Neuromuscular complications are almost universal in CKD by the time that a patient commences dialysis. Recent studies have indicated that chronic hyperkalemia may contribute to the development of neuropathy in CKD. This study was undertaken to determine whether dietary restriction of potassium intake may be a neuroprotective factor in CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A 24-month prospective, single-blind, randomized, controlled trial was undertaken in 47 consecutively recruited patients with stages 3 and 4 CKD. The intervention arm (n=23) was prescribed a diet focusing on potassium restriction to meet a monthly serum potassium level of ≤4.5 mEq/L, with oral sodium polystyrene sulfonate provided if dietary advice failed to achieve the target. The control arm (n=24) received dietary advice regarding general nutrition. The primary outcome was the change in the total neuropathy score evaluated by a blinded observer. Secondary outcomes included electrolyte levels, gait speed, neurophysiologic parameters, and health-related quality of life scores. Five patients withdrew before initiation of treatment, and final analysis consisted of n=21 in each group.

RESULTS

There was a greater increase in total neuropathy score from baseline to final assessment in the control arm compared with the intervention arm (6.1±6.2-8.6±7.9 controls; 7.8±7.4-8.2±7.5 intervention; change 2.8±3.3-0.4±2.2, respectively; P<0.01). The intervention significantly reduced mean serum potassium compared with controls (4.6±0.1-4.8±0.1 mEq/L mean recorded every 6 months over the trial duration; P=0.03). There were no adverse changes in other nutritional parameters. Improved gait speed was also noted in the intervention arm compared with the control arm, with a mean increase of 0.15±0.17 m/s in the intervention group versus 0.02±0.16 m/s in the control group (P=0.01).

CONCLUSIONS

Our results provide important preliminary evidence that dietary potassium restriction confers neuroprotection in CKD and should be confirmed in a larger multicenter trial.

Risk Factors and Outcomes of Thalidomide-induced Peripheral Neuropathy in a Pediatric Inflammatory Bowel Disease Cohort

BACKGROUND

Thalidomide is an effective therapy in children with inflammatory bowel disease refractory to standard treatments, but thalidomide-induced peripheral neuropathy (TiPN) limits its long-term use. We aimed to investigate the risk factors and the outcome of TiPN in children with inflammatory bowel disease.

METHODS

Within a retrospective multicenter cohort study, we evaluated prevalence and evolution of TiPN. Clinical data and candidate genetic profiles of patients with and without TiPN were compared with detect predisposing factors.

RESULTS

One hundred forty-two patients were identified. TiPN was found in 72.5% of patients (38.7% clinical and instrumental alterations, 26.8% exclusive electrophysiological anomalies, and 7.0% exclusive neurological symptoms). Median TiPN-free period of treatment was 16.5 months; percentage of TiPN-free patients was 70.0% and 35.6% at 12 and 24 months of treatment, respectively. The risk of TiPN increased depending on the mean daily dose (50-99 mg/d adjusted hazard ratio 2.62; 95% confidence interval [CI], 1.31-5.21; 100-149 mg/d adjusted hazard ratio 6.16; 95% CI, 20.9-13.06; >150 mg/d adjusted hazard ratio 9.57; 95% CI, 2.6-35.2). Single nucleotide polymorphisms in ICAM1 (rs1799969) and SERPINB2 (rs6103) genes were found to be protective against TiPN (odds ratio 0.15; 95% CI, 0.03-0.82 and 0.36; 95% CI, 0.14-0.88, respectively). TiPN was the cause of drug suspension in 41.8% of patients. Clinical symptoms resolved in 89.2% of cases, whereas instrumental alteration persisted in more than half of the patients during a short follow-up.

CONCLUSIONS

In children with inflammatory bowel disease, TiPN is common but mild and generally reversible. Cumulative dose seems to be the most relevant risk factor, whereas polymorphisms in genes involved in neuronal inflammation may be protective.

Balance impairment in kidney transplant recipients without concurrent peripheral neuropathy

Kidney transplant recipients (KTRs) present with compromised functional capacity, low levels of physical activity, muscle atrophy, and peripheral nerve dysfunction that may result in high postural instability. This study aimed to compare the static balance control of 19 KTRs with 19 healthy adults (HA). All participants completed the Romberg test on a stabilometric platform with eyes open (EO), eyes closed (EC) and during a dual task (DT) condition. Centre of pressure (COP) measures (COP velocity (COPv) and sway area (SA)), as well as position-based outcomes such as anterior-posterior (AP) and medio-lateral (ML) ranges of COP displacements were recorded. Independent ANCOVA revealed an overall lower performance of KTRs compared to HA (p<0.05) with the EC condition exhibiting the worst relative performance for KTRs, suggesting a poorer capacity of relying on proprioceptive information when maintaining the upright posture. The addition of a cognitive task did not further worsen balance performance in KTRs. As impaired postural control is one of the main predictors of falls in elderly subjects, these data might also indicate that this constitutes an equivalent risk factor for falling in middle-aged KTRs.

Two Decades of Tacrolimus in Renal Transplant: Basic Science and Clinical Evidences

Tacrolimus, a calcineurin inhibitor, has been the cornerstone of immunosuppressive regimens in renal transplant over 2 decades. This has significantly improved the outcomes of renal transplant, including reduction of acute rejection episodes, improvement of renal function and graft survival, and reduction of some of the adverse effects associated with cyclosporine. However, use of tacrolimus is associated with a number of undesirable effects, such as nephrotoxicity, posttransplant diabetes mellitus, neurotoxicity, and cosmetic and electrolyte disturbances. To alleviate these effects, several strategies have been adopted to minimize or eliminate tacrolimus from maintenance regimens of immunosuppression, with some success. This review focuses on advancements in the understanding of the basic science related to tacrolimus and the clinical evidences that have examined the efficacy and safety of tacrolimus in renal transplant over the past 2 decades and highlights the future directions.

Severe Epidermal Nerve Fiber Loss in Diabetic Neuropathy Is Not Reversed by Long-Term Normoglycemia After Simultaneous Pancreas and Kidney Transplantation

Whether nerve fiber loss, a prominent feature of advanced diabetic neuropathy, can be reversed by reestablishment of normal glucose control remains questionable. We present 8-year follow-up data on epidermal nerve fiber (ENF) density and neurological function in patients with type 1 diabetes after simultaneous pancreas and kidney transplantation (SPK) with long-term normoglycemia. Distal thigh skin biopsies with ENF counts, vibration perception thresholds (VPTs), autonomic function testing (AFT) and electrophysiological examinations were performed at time of SPK and 2.5 and 8 years after SPK in 12 patients with type 1 diabetes. In comparison to controls, baseline ENF density, VPT and AFT results of patients indicated severe neuropathy. At follow-up, all SPK recipients were insulin independent with excellent glycemic control and kidney graft function; however, the severe ENF depletion present at baseline had not improved, with total ENF absence in 11 patients at 8-year follow-up. Similarly, no amelioration occurred in the VPT and AFT results. Numerical improvement was seen in some electrophysiological parameters; however, statistical significance was achieved only in median motor nerve conduction velocity. ENF loss and functional deficits in advanced diabetic peripheral neuropathy are rarely reversible, even by long-term normoglycemia, which underscores the importance of neuropathy prevention by early optimal glycemic control.

The neurology of solid organ transplantation

Transplantation is the rescue treatment for end-stage organ failure with more than 110,000 solid organs transplantations performed worldwide annually. Recent advances in transplantation procedures and posttransplantation management have improved long-term survival and quality of life of transplant recipients, shifting the focus from acute perioperative critical care needs toward long-term chronic medical problems. Neurologic complications affect up to 30-60 % of solid organ transplant recipients. Common etiologies include opportunistic infections and toxicities of antirejection medications, and wide spectrum of toxic and metabolic disturbances. Most complications are common to all allograft types, but some are relatively specific for individual allograft types (e.g., central pontine myelinolysis in liver transplant recipients). Close collaboration between neurologists and other transplant team members is essential for effective management. Early recognition of complications and accurate diagnosis leading to timely treatment is essential to reduce the morbidity and improve the overall transplant outcome.

Neurological complications in chronic kidney disease

Patients with chronic kidney disease (CKD) are frequently afflicted with neurological complications. These complications can potentially affect both the central and peripheral nervous systems. Common neurological complications in CKD include stroke, cognitive dysfunction, encephalopathy, peripheral and autonomic neuropathies. These conditions have significant impact not only on patient morbidity but also on mortality risk through a variety of mechanisms. Understanding the pathophysiological mechanisms of these conditions can provide insights into effective management strategies for neurological complications. This review describes clinical management of neurological complications in CKD with reference to the contributing physiological and pathological derangements. Stroke, cognitive dysfunction and dementia share several pathological mechanisms that may contribute to vascular impairment and neurodegeneration. Cognitive dysfunction and dementia may be differentiated from encephalopathy which has similar contributing factors but presents in an acute and rapidly progressive manner and may be accompanied by tremor and asterixis. Recent evidence suggests that dietary potassium restriction may be a useful preventative measure for peripheral neuropathy. Management of painful neuropathic symptoms can be achieved by pharmacological means with careful dosing and side effect considerations for reduced renal function. Patients with autonomic neuropathy may respond to sildenafil for impotence. Neurological complications often become clinically apparent at end-stage disease, however early detection and management of these conditions in mild CKD may reduce their impact at later stages.

T-cell alloreactivity and transplantation outcome: a budding role for heterologous immunity?

PURPOSE OF REVIEW

Despite the association between alloreactive T cells and poor graft survival, the mechanisms behind T-cell-mediated rejection are still under investigation. In this review, we will discuss the latest insights into the impact of T-cell alloreactivity on solid organ transplantation and hematopoietic stem cell transplantation (HSCT), with special emphasis on the potential impact of heterologous immunity.

RECENT FINDINGS

A large part of the memory T-cell repertoire is induced upon virus infections, and evidence for a role of T-cell receptor cross-reactivity of virus-induced memory T cells against allogeneic human leukocyte antigen (HLA) is accumulating in experimental and clinical solid organ transplantation studies. In HSCT, strong alloreactive potential of naïve T cells causes concerns for graft-versus-host disease while additional HLA-DP matching is suggested to prevent CD4 alloreactivity. Furthermore, virus-induced memory T cells hamper mixed chimerism induction, pointing once more towards a role for heterologous immunity.

SUMMARY

Both memory and naïve T cells contribute to the alloimmune response after transplantation. Monitoring for T-cell phenotypes could help predict rejection episodes and/or graft-versus-host disease, allowing timely intervention. Tailoring donor lymphocyte infusions and additional HLA matching could prevent strong alloreactivity in HSCT. Furthermore, the potential role of heterologous immunity in T-cell alloreactivity and transplantation is gaining interest.

Preventing Allograft Rejection by Targeting Immune Metabolism

Upon antigen recognition and co-stimulation, T lymphocytes upregulate the metabolic machinery necessary to proliferate and sustain effector function. This metabolic reprogramming in T cells regulates T cell activation and differentiation but is not just a consequence of antigen recognition. Although such metabolic reprogramming promotes the differentiation and function of T effector cells, the differentiation of regulatory T cells employs different metabolic reprogramming. Therefore, we hypothesized that inhibition of glycolysis and glutamine metabolism might prevent graft rejection by inhibiting effector generation and function and promoting regulatory T cell generation. We devised an anti-rejection regimen involving the glycolytic inhibitor 2-deoxyglucose (2-DG), the anti-type II diabetes drug metformin, and the inhibitor of glutamine metabolism 6-diazo-5-oxo-L-norleucine (DON). Using this triple-drug regimen, we were able to prevent or delay graft rejection in fully mismatched skin and heart allograft transplantation models.