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

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.

Evaluation of Tacrolimus' Adverse Effects on Zebrafish in Larval and Adult Stages by Using Multiple Physiological and Behavioral Endpoints

Tacrolimus (FK506) is a common immunosuppressant that is used in organ transplantation. However, despite its importance in medical applications, it is prone to adverse side effects. While some studies have demonstrated its toxicities to humans and various animal models, very few studies have addressed this issue in aquatic organisms, especially zebrafish. Here, we assessed the adverse effects of acute and chronic exposure to tacrolimus in relatively low doses in zebrafish in both larval and adult stages, respectively. Based on the results, although tacrolimus did not cause any cardiotoxicity and respiratory toxicity toward zebrafish larvae, it affected their locomotor activity performance in light-dark locomotion tests. Meanwhile, tacrolimus was also found to slightly affect the behavior performance, shoaling formation, circadian rhythm locomotor activity, and color preference of adult zebrafish in a dose-dependent manner. In addition, alterations in the cognitive performance of the fish were also displayed by the treated fish, indicated by a loss of short-term memory. To help elucidate the toxicity mechanism of tacrolimus, molecular docking was conducted to calculate the strength of the binding interaction between tacrolimus to human FKBP12. The results showed a relatively normal binding affinity, indicating that this interaction might only partly contribute to the observed alterations. Nevertheless, the current research could help clinicians and researchers to further understand the toxicology of tacrolimus, especially to zebrafish, thus highlighting the importance of considering the toxicity of tacrolimus prior to its usage.

Understanding the impact of pediatric kidney transplantation on cognition: A review of the literature

BACKGROUND

Chronic kidney disease (CKD) is a relatively rare childhood disease that is associated with a wide array of medical comorbidities. Roughly half of all pediatric patients acquire CKD due to congenital anomalies of the kidneys and urinary tract, and of those with congenital disease, 50% will progress to end-stage kidney disease (ESKD) necessitating a kidney transplantation. The medical sequelae of advanced CKD/ESKD improve dramatically following successful kidney transplantation; however, the impact of kidney transplantation on neurocognition in children is less clear. It is generally thought that cognition improves following kidney transplantation; however, our knowledge on this topic is limited by the sparsity of high-quality data in the context of the relative rarity of pediatric CKD/ESKD.

METHOD

We conducted a narrative review to gauge the scope of the literature, using the PubMed database and the following keywords: cognition, kidney, brain, pediatric, neurocognition, intelligence, executive function, transplant, immunosuppression, and neuroimaging.

RESULTS

There are few published longitudinal studies, and existing work often includes wide heterogeneity in age at transplant, variable dialysis exposure/duration prior to transplant, and unaccounted cofounders which persist following transplantation, including socio-economic status. Furthermore, the impact of long-term maintenance immunosuppression on the brain and cognitive function of pediatric kidney transplant (KT) recipients remains unknown.

CONCLUSION

In this educational review, we highlight what is known on the topic of neurocognition and neuroimaging in the pediatric KT population.

Neurocognitive deficits may not resolve following pediatric kidney transplantation

BACKGROUND

Pediatric chronic kidney disease (CKD) patients are at risk for cognitive deficits with worsening disease progression. Limited, existing cross-sectional studies suggest that cognitive deficits may improve following kidney transplantation. We sought to assess cognitive performance in relationship to kidney transplantation and kidney-specific medical variables in a sample of pediatric kidney transplant patients who provided cross-sectional and longitudinal observations.

METHODS

A retrospective chart review was conducted in patients who completed pre- and/or post-transplant neurocognitive testing at the University of Iowa from 2015-2021. Cognitive outcomes were investigated with developmentally appropriate, standardized measures. Mixed linear models estimated the impact of transplant status on cognitive function (z-scores). Subsequent post-hoc t-tests on change scores were limited to patients who had provided pre- and post-transplant assessments.

RESULTS

Thirty eight patients underwent cognitive assessments: 10 had both pre- and post-transplant cognitive assessments, 11 had pre-transplant assessments only, and 17 had post-transplant data only. Post-transplant status was associated with significantly lower full-scale IQ and slower processing speed compared to pre-transplant status (estimate = -0.32, 95% confidence interval [CI] = -0.52: -0.12; estimate = -0.86, CI = -1.17: -0.55, respectively). Post-hoc analyses confirmed results from the mixed models (FSIQ change score = -0.34, 95% CI = -0.56: -0.12; processing speed change score = -0.98, CI = -1.28: -0.68). Finally, being ≥80 months old at transplant was associated with substantially lower FSIQ compared to being <80 months (estimate = -1.25, 95% CI = -1.94: -0.56).

CONCLUSIONS

Our results highlight the importance of monitoring cognitive function following pediatric kidney transplant and identify older transplant age as a risk factor for cognitive deficits.

Topiramate potential neurotoxicity and mitigating role of ginger oil in mice brain

Topiramate has multiple pharmacological mechanisms that are efficient in treating epilepsy and migraine. Ginger has been established to have gingerols and shogaols that cause migraine relief. Moreover, Topiramate has many off-label uses. Thus, it was necessary to explore the possible neurotoxicity of Topiramate and the role of ginger oil in attenuating the Topiramate neurotoxicity. Male albino mice were orally gavaged with Topiramate, ginger oil (400 mg/kg), and Topiramate plus ginger oil with the same pattern for 28 days. Oxidative stress markers, acetylcholinesterase (AchE), gamma-aminobutyric acid (GABA), and tumor necrosis factor-alpha (TNF-α) were examined. Histopathological examination, immunohistochemical glial fibrillary acidic protein (GFAP), and Bax expression analysis were detected. The GABAAR subunits, Gabra1, Gabra3, and Gabra5 expression, were assessed by RT-qPCR. The investigation showed that Topiramate raised oxidative stress markers levels, neurotransmitters, TNF-α, and diminished glutathione (GSH). In addition, Topiramate exhibited various neuropathological alterations, strong Bax, and GFAP immune-reactivity in the cerebral cortex. At the same time, the results indicated that ginger oil had no neurotoxicity. The effect of Topiramate plus ginger oil alleviated the changes induced by Topiramate in the tested parameters. Both Topiramate and ginger oil upregulated the mRNA expression of gabra1 and gabra3, while their interaction markedly downregulated them. Therefore, it could be concluded that the Topiramate overdose could cause neurotoxicity, but the interaction with ginger oil may reduce Topiramate-induced neurotoxicity and should be taken in parallel.