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Therapeutic Potential of Sodium Channel Blockers as a Targeted Therapy Approach in KCNA1-Associated Episodic Ataxia and a Comprehensive Review of the Literature.

ABSTRACT: Introduction: Among genetic paroxysmal movement disorders, variants in ion channel coding genes constitute a major subgroup. Loss-of-function (LOF) variants in KCNA1, the gene coding for K_V1.1 channels, are associated with episodic ataxia type 1 (EA1), characterized by seconds to minutes-lasting attacks including gait incoordination, limb ataxia, truncal instability, dysarthria, nystagmus, tremor, and occasionally seizures, but also persistent neuromuscular symptoms like myokymia or neuromyotonia. Standard treatment has not yet been developed, and different treatment efforts need to be systematically evaluated. Objective and Methods: Personalized therapeutic regimens tailored to disease-causing pathophysiological mechanisms may offer the specificity required to overcome limitations in therapy. Toward this aim, we (i) reviewed all available clinical reports on treatment response and functional consequences of KCNA1 variants causing EA1, (ii) examined the potential effects on neuronal excitability of all variants using a single compartment conductance-based model and set out to assess the potential of two sodium channel blockers (SCBs: carbamazepine and riluzole) to restore the identified underlying pathophysiological effects of K_V1.1 channels, and (iii) provide a comprehensive review of the literature considering all types of episodic ataxia. Results: Reviewing the treatment efforts of EA1 patients revealed moderate response to acetazolamide and exhibited the strength of SCBs, especially carbamazepine, in the treatment of EA1 patients. Biophysical dysfunction of K_V1.1 channels is typically based on depolarizing shifts of steady-state activation, leading to an LOF of KCNA1 variant channels. Our model predicts a lowered rheobase and an increase of the firing rate on a neuronal level. The estimated concentration dependent effects of carbamazepine and riluzole could partially restore the altered gating properties of dysfunctional variant channels. Conclusion: These data strengthen the potential of SCBs to contribute to functional compensation of dysfunctional K_V1.1 channels. We propose riluzole as a new drug repurposing candidate and highlight the role of personalized approaches to develop standard care for EA1 patients. These results could have implications for clinical practice in future and highlight the need for the development of individualized and targeted therapies for episodic ataxia and genetic paroxysmal disorders in general.

SUBMITTER: Lauxmann S

PROVIDER: S-EPMC8459024 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundPeople with cystic fibrosis (CF) have increased transport of the salt, sodium across their airway lining. Over-absorption of sodium results in the dehydration of the liquid that lines the airway surface and (along with defective chloride secretion) is a primary defect in people with CF.ObjectivesTo determine whether the topical administration of drugs that block sodium transport improves the respiratory condition of people with CF.Search methodsWe searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We contacted principal investigators known to work in the field, previous authors and pharmaceutical companies who manufacture ion transport agents for unpublished or follow-up data.Most recent search of the Group's register: 19 December 2013.Selection criteriaPublished or unpublished randomised controlled trials (RCTs) or quasi-randomised controlled trials of sodium channel blockers compared to placebo or another sodium channel blocker or the same sodium channel blocker at a different dosing regimen.Data collection and analysisTwo authors independently extracted data. Meta-analysis was limited due to differing study designs.Main resultsFive RCTs, with a total of 226 participants, examining the topical administration of the short-acting sodium channel blocker, amiloride, compared to placebo were identified as eligible for inclusion in the review. In three studies over six months, there was a significant difference found in the difference in relative change in FVC in favour of placebo (weighted mean difference 1.51% (95% confidence interval -2.77 to -0.25), although heterogeneity was evident. A two-week study demonstrated that hypertonic saline with amiloride pre-treatment did not result in a significant improvement in respiratory function or mucus clearance, in contrast to pre-treatment with placebo. There were no significant differences identified in other clinically relevant outcomes.Authors' conclusionsWe found no evidence that the topical administration of a short-acting sodium channel blocker improves respiratory condition in people with cystic fibrosis and some limited evidence of deterioration in lung function.

Project description:BackgroundMultiple sclerosis (MS) is an autoimmune, inflammatory, demyelinating disease of the central nervous system (CNS), which can occur in many parts of the CNS and result in a wide range of symptoms including sensory impairment, fatigue, walking or balance problems, visual impairment, vertigo and cognitive disabilities. At present, the most commonly used MS treatments are immunomodulating agents, but they have little effect on the disability. Experimental studies show that sodium (Na(+)) accumulation leads to intracellular calcium (Ca(2+)) release, and the increased calcium levels can activate nitric oxide synthase and harmful proteases and lipases. These factors contribute to axonal injury in people with MS. If partial blockade of voltage-gated sodium channels could result in neuroprotection, this would be of benefit for preventing disability progression in these people. Neuroprotection is emerging as a potentially important strategy for preventing disability progression in people with MS.ObjectivesTo assess the efficacy and safety of sodium channel blockers for neuroprotection in people with MS to prevent the occurrence of disability and alleviate the burden of the disease.Search methodsWe searched the Cochrane Multiple Sclerosis and Rare Diseases of the Central Nervous System Group Specialised Register (27 August 2015) which, among other sources, contains references from the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library 2015, Issue (8), MEDLINE (1966 to August 2015), EMBASE (1974 to August 2015), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1981 to August 2015), Latin American and Caribbean Health Science Information Database (LILACS) (1982 to August 2015), ClinicalTrials.gov (http://clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Portal (ICTRP) search portal (http://apps.who.int/trialsearch). In addition, we searched four Chinese databases, ongoing trials registers and relevant reference lists.Selection criteriaRandomised controlled trials (RCTs) that examined sodium channel blockers used alone or as an add-on to any approved treatments for MS.Data collection and analysisTwo review authors independently selected trials, assessed trial quality and extracted the data.Main resultsOnly one study evaluating lamotrigine in secondary progressive MS was eligible. One hundred and twenty people were included, 61 randomly assigned to lamotrigine treatment and 59 to placebo treatment. The average age of participants in the two groups was 51.9 years and 50.1 years, respectively. The proportion of male participants was 27.5%. The period of follow-up was 2 years. No data were found on disability progression and people who experienced relapses. No significant differences were found for serious adverse events between the two groups. Treatment with lamotrigine was associated with more rashes (20% vs 5%, P value 0.03) and transient, dose-related deterioration of mobility (66% vs 34%, P value 0.001) than placebo. Furthermore, no significant difference between the two groups was found in the magnetic resonance imaging (MRI) measurements of cerebral atrophy, Expanded Disability Status Score changes, Multiple Sclerosis Functional Composite score changes. This study was judged to be at high risk of bias. This review will be updated when the three ongoing studies we identified are completed.Authors' conclusionsThe quality of evidence was judged to be very low due to the low number of available studies and included participants. There is a lack of evidence to address the review question on the efficacy of sodium channel blockers for people with MS. Assessment of the three ongoing trials might change this conclusion. Further high-quality large scale studies are needed.

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Therapeutic Potential of Sodium Channel Blockers as a Targeted Therapy Approach in KCNA1-Associated Episodic Ataxia and a Comprehensive Review of the Literature.

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