High-content screening identifies a small molecule that restores AP-4-dependent protein trafficking in neuronal models of AP-4-associated hereditary spastic paraplegia

Unbiased phenotypic screens in patient-relevant disease models offer the potential to detect therapeutic targets for rare diseases. In this study, we developed a high-throughput screening assay to identify molecules that correct aberrant protein trafficking in adapter protein complex 4 (AP-4) deficiency, a rare but prototypical form of childhood-onset hereditary spastic paraplegia characterized by mislocalization of the autophagy protein ATG9A. Using high-content microscopy and an automated image analysis pipeline, we screened a diversity library of 28,864 small molecules and identified a lead compound, BCH-HSP-C01, that restored ATG9A pathology in multiple disease models, including patient-derived fibroblasts and induced pluripotent stem cell-derived neurons. We used multiparametric orthogonal strategies and integrated transcriptomic and proteomic approaches to delineate potential mechanisms of action of BCH-HSP-C01. Our results define molecular regulators of intracellular ATG9A trafficking and characterize a lead compound for the treatment of AP-4 deficiency, providing important proof-of-concept data for future studies.

Characteristics of Changes in Intrathecal Baclofen Dosage over Time due to Causative Disease

Intrathecal baclofen (ITB) therapy effectively treats spasticity caused by brain or spinal cord lesions. However, only a few studies compare the course of treatment for different diseases. We investigated the change in daily dose of baclofen per year and its associated adverse events in patients presenting with the three most common etiologies at our institute: hereditary spastic paraplegia, cerebral palsy, and spinal cord injury. The ITB pumps were implanted from July 2007 to August 2019, with a mean follow-up period of 70 months. In patients with hereditary spastic paraplegia, baclofen dosage was reduced after eight years following ITB introduction, and the treatment was terminated in one patient owing to disease progression. In patients with cerebral palsy, the dosage increased gradually, and became constant in the 11th year. Patients with spinal cord injury gradually increased their baclofen dosage throughout the entire observation period. Severity and adverse event rates were higher in patients with cerebral palsy than in others. The degree and progression of spasticity varied depending on the causative disease. Understanding the characteristics and natural history of each disease is important when continuing ITB treatment.

Dalfampridine as a promising agent in the management of hereditary spastic paraplegia: A triple-blinded, randomized, placebo-controlled pilot trial

Limited but encouraging results support the use of dalfampridine in patients with hereditary spastic paraplegia (HSP). Our aim was to investigate the effects of dalfampridine on walking speed, muscle length, spasticity, functional strength, and functional mobility in patients with HSP. In this triple-blinded, randomized, placebo-controlled pilot trial, four patients with HSP received dalfampridine (10 mg twice daily) in addition to physiotherapy (twice a week), and four patients received placebo in addition to physiotherapy for eight weeks. The group allocation was masked from the assessor, treating physiotherapists, and patients. The primary outcome was the Timed 25-foot Walk Test (T25FWT) at the end of the eight-week treatment. The secondary outcome measures were functional mobility, functional muscle strength, muscle length, and spasticity. The improvement in the T25FWT values was significantly higher in the experimental group than in the control group (p < 0.05). All patients in the experimental group exceeded the proposed minimally important clinical difference for T25FWT. The degrees of improvement in most muscle length and spasticity assessments and functional muscle strength were also higher in the experimental group (p < 0.05). No significant difference was observed between the groups regarding functional mobility (p > 0.05). No adverse events or side effects were noted. This pilot trial yields encouraging evidence that the combination of dalfampridine and physiotherapy may enhance muscle parameters and improve walking speed in patients with HSP. However, further research involving larger sample sizes and more comprehensive assessments is needed to validate these results and establish the clinical benefits of this treatment approach. Trial registration ID: NCT05613114 (https://clinicaltrials.gov/), retrospectively registered on November 14, 2022.

AMFR dysfunction causes autosomal recessive spastic paraplegia in human that is amenable to statin treatment in a preclinical model

Hereditary spastic paraplegias (HSP) are rare, inherited neurodegenerative or neurodevelopmental disorders that mainly present with lower limb spasticity and muscle weakness due to motor neuron dysfunction. Whole genome sequencing identified bi-allelic truncating variants in AMFR, encoding a RING-H2 finger E3 ubiquitin ligase anchored at the membrane of the endoplasmic reticulum (ER), in two previously genetically unexplained HSP-affected siblings. Subsequently, international collaboration recognized additional HSP-affected individuals with similar bi-allelic truncating AMFR variants, resulting in a cohort of 20 individuals from 8 unrelated, consanguineous families. Variants segregated with a phenotype of mainly pure but also complex HSP consisting of global developmental delay, mild intellectual disability, motor dysfunction, and progressive spasticity. Patient-derived fibroblasts, neural stem cells (NSCs), and in vivo zebrafish modeling were used to investigate pathomechanisms, including initial preclinical therapy assessment. The absence of AMFR disturbs lipid homeostasis, causing lipid droplet accumulation in NSCs and patient-derived fibroblasts which is rescued upon AMFR re-expression. Electron microscopy indicates ER morphology alterations in the absence of AMFR. Similar findings are seen in amfra-/- zebrafish larvae, in addition to altered touch-evoked escape response and defects in motor neuron branching, phenocopying the HSP observed in patients. Interestingly, administration of FDA-approved statins improves touch-evoked escape response and motor neuron branching defects in amfra-/- zebrafish larvae, suggesting potential therapeutic implications. Our genetic and functional studies identify bi-allelic truncating variants in AMFR as a cause of a novel autosomal recessive HSP by altering lipid metabolism, which may potentially be therapeutically modulated using precision medicine with statins.

A novel KIAA0196 mutation in a Chinese patient with spastic paraplegia 8: A case report

RATIONALE

We report a case of Spastic paraplegia 8 (SPG8) with a novel mutation of KIAA0196 gene.

PATIENTS CONCERNS

A 12-year-old boy presented as ankle sprained, lower limb stiffness, abnormal gait since he was 5 years old.

DIAGNOSES

The next generation sequence showed a novel c.1128delG (p.L376fs) mutation in KIAA0196 gene, the electromyography showed the pyramidal tract conduction dysfunction and deep sensory conduction abnormalities of lower limbs without motor neuron damage. The diagnose was SPG8.

INTERVENTIONS

Patient was gaven Baclofen treatment (30 mg/day, orally).

OUTCOMES

At one year follow up, his symptoms didn't improved.

LESSONS

We describe a novel KIAA0196 c.1128del.G (p.L376fs) mutation in a Chinese patient with SPG8. To our knowledge, it's the first frame delete mutation causing shift mutation of KIAA0196 gene, resulting in the earliest onset of SPG8 in the world. Gene sequencing is a powerful diagnostic tool to identify a causal mutation in genetically heterogeneous HSP.

Hereditary spastic paraplegia type 5: natural history, biomarkers and a randomized controlled trial

Spastic paraplegia type 5 (SPG5) is a rare subtype of hereditary spastic paraplegia, a highly heterogeneous group of neurodegenerative disorders defined by progressive neurodegeneration of the corticospinal tract motor neurons. SPG5 is caused by recessive mutations in the gene CYP7B1 encoding oxysterol-7α-hydroxylase. This enzyme is involved in the degradation of cholesterol into primary bile acids. CYP7B1 deficiency has been shown to lead to accumulation of neurotoxic oxysterols. In this multicentre study, we have performed detailed clinical and biochemical analysis in 34 genetically confirmed SPG5 cases from 28 families, studied dose-dependent neurotoxicity of oxysterols in human cortical neurons and performed a randomized placebo-controlled double blind interventional trial targeting oxysterol accumulation in serum of SPG5 patients. Clinically, SPG5 manifested in childhood or adolescence (median 13 years). Gait ataxia was a common feature. SPG5 patients lost the ability to walk independently after a median disease duration of 23 years and became wheelchair dependent after a median 33 years. The overall cross-sectional progression rate of 0.56 points on the Spastic Paraplegia Rating Scale per year was slightly lower than the longitudinal progression rate of 0.80 points per year. Biochemically, marked accumulation of CYP7B1 substrates including 27-hydroxycholesterol was confirmed in serum (n = 19) and cerebrospinal fluid (n = 17) of SPG5 patients. Moreover, 27-hydroxycholesterol levels in serum correlated with disease severity and disease duration. Oxysterols were found to impair metabolic activity and viability of human cortical neurons at concentrations found in SPG5 patients, indicating that elevated levels of oxysterols might be key pathogenic factors in SPG5. We thus performed a randomized placebo-controlled trial (EudraCT 2015-000978-35) with atorvastatin 40 mg/day for 9 weeks in 14 SPG5 patients with 27-hydroxycholesterol levels in serum as the primary outcome measure. Atorvastatin, but not placebo, reduced serum 27-hydroxycholesterol from 853 ng/ml [interquartile range (IQR) 683-1113] to 641 (IQR 507-694) (-31.5%, P = 0.001, Mann-Whitney U-test). Similarly, 25-hydroxycholesterol levels in serum were reduced. In cerebrospinal fluid 27-hydroxycholesterol was reduced by 8.4% but this did not significantly differ from placebo. As expected, no effects were seen on clinical outcome parameters in this short-term trial. In this study, we define the mutational and phenotypic spectrum of SPG5, examine the correlation of disease severity and progression with oxysterol concentrations, and demonstrate in a randomized controlled trial that atorvastatin treatment can effectively lower 27-hydroxycholesterol levels in serum of SPG5 patients. We thus demonstrate the first causal treatment strategy in hereditary spastic paraplegia.

Use of sugammadex in Strumpell-Lorrain disease: a report of two cases

CONTENT

Strumpell-Lorrain disease - or familial spastic paraplegia (FSP) - is a rare hereditary neurological disorder, mainly characterized by variable degrees of stiffness and weakening of the muscles, with cognitive impairment, deafness, and ataxia in the more severe cases. We describe two female siblings with FSP programmed for cholecystectomy and subtotal colectomy, respectively, and also how we dealt with the anesthetic management in both cases and review the literature on this disease in relation to anesthesia.

Neurotransmitter abnormalities and response to supplementation in SPG11

OBJECTIVE

To report the detection of secondary neurotransmitter abnormalities in a group of SPG11 patients and describe treatment with l-dopa/carbidopa and sapropterin.

DESIGN

Case reports.

SETTING

National Institutes of Health in the Undiagnosed Disease Program; Children's National Medical Center in the Myelin Disorders Bioregistry Program.

PATIENTS

Four SPG11 patients with a clinical picture of progressive spastic paraparesis complicated by extrapyramidal symptoms and maculopathy.

INTERVENTIONS

L-Dopa/carbidopa and sapropterin.

RESULTS

3/4 patients presented secondary neurotransmitter abnormalities; 4/4 partially responded to L-dopa as well as sapropterin.

CONCLUSIONS

In the SPG11 patient with extrapyramidal symptoms, a trial of L-dopa/carbidopa and sapropterin and/or evaluation of cerebrospinal fluid neurotransmitters should be considered.

Hereditary spastic paraplegia, bipolar affective disorder and intellectual disability: a case report

This is a case report of a gentleman with an intellectual impairment who presented with both hereditary spastic paraplegia (HSD) and bipolar affective disorder (BPAD), a combination that has not yet been described in the professional literature. A limited number of articles have suggested an association between HSP and an organic personality disorder. We describe the case of a gentleman who was diagnosed with BPAD in his early adult life and displayed neurological symptoms of HSP at around the same time. Diagnosis of both HSP and BPAD can be difficult and is further compounded by an intellectual impairment. Treatment options may be limited by the propensity of many psychotropic medications to cause movement disorders and thus worsening neurological symptoms.

The genetics of hereditary spastic paraplegia and implications for drug therapy

Hereditary spastic paraplegia (HSP) comprises a group of clinically and genetically heterogeneous diseases that affect the upper motor neurons and their axonal projections. A total of 30 chromosomal loci have been identified for autosomal dominant, recessive and X-linked HSP. The underlying genes for 15 of these loci have been described. The molecular dissection of the cellular functions of the related gene products has already greatly advanced our understanding of the most critical pathways involved in HSP. It is hoped that in the foreseeable future this knowledge will begin to translate into novel pharmacological approaches for this devastating disease.

Double-blind crossover trial of gabapentin in SPG4-linked hereditary spastic paraplegia

Patients with hereditary spastic paraplegia (HSP) are often treated with antispastic drugs to relieve symptoms but documentation is lacking. In this study, gabapentin was tested in a double-blind crossover trial on a group of patients with HSP and linkage to the SPG4 locus. There was no difference between periods with gabapentin and placebo treatment in clinical assessment, self-reported parameters or paired transcranial magnetic stimulation evaluation of motor cortical excitability.

Hereditary spastic paraplegia: clinical genomics and pharmacogenetic perspectives

Hereditary spastic paraplegias (HSPs) are a group of single-gene disorders characterised by degeneration of the corticospinal tract axons, leading to bilateral, symmetrical, slowly-progressive spastic paraparesis, predominantly of the lower extremities. So far, ~ 30 different chromosomal HSP loci have been identified by genetic linkage analysis. Defects in intracellular trafficking and transport in myelination and abnormalities of mitochondrial proteins have been involved in HSP pathogenesis. At present, treatment of the HSPs is primarily directed symptomatically toward reducing muscle spasticity. Yet, recent progresses in the identification of HSP mutations are providing formidable tools to pharmacogenetic approaches of drug discovery, validation and prediction of individual response.

Hereditary spastic paraplegia associated with dopa-responsive parkinsonism

A 47-year-old patient with hereditary spastic paraplegia and parkinsonian features is reported. Treatment with levodopa led to marked improvement in his neurological status and quality of life. However, several years later he developed motor fluctuations and dyskinesias. The latter promptly remitted with amantadine treatment.

Disease-related phenotypes in a Drosophila model of hereditary spastic paraplegia are ameliorated by treatment with vinblastine

Hereditary spastic paraplegias (HSPs) are a group of neurodegenerative diseases characterized by progressive weakness and spasticity of the lower limbs. Dominant mutations in the human SPG4 gene, encoding spastin, are responsible for the most frequent form of HSP. Spastin is an ATPase that binds microtubules and localizes to the spindle pole and distal axon in mammalian cell lines. Furthermore, its Drosophila homolog, Drosophila spastin (Dspastin), has been recently shown to regulate microtubule stability and synaptic function at the Drosophila larval neuromuscular junction. Here we report the generation of a spastin-linked HSP animal model and show that in Drosophila, neural knockdown of Dspastin and, conversely, neural overexpression of Dspastin containing a conserved pathogenic mutation both recapitulate some phenotypic aspects of the human disease, including adult onset, locomotor impairment, and neurodegeneration. At the subcellular level, neuronal expression of both Dspastin RNA interference and mutant Dspastin cause an excessive stabilization of microtubules in the neuromuscular junction synapse. In addition, we provide evidence that administration of the microtubule targeting drug vinblastine significantly attenuates these phenotypes in vivo. Our findings demonstrate that loss of spastin function elicits HSP-like phenotypes in Drosophila, provide novel insights into the molecular mechanism of spastin mutations, and raise the possibility that therapy with Vinca alkaloids may be efficacious in spastin-associated HSP and other disorders related to microtubule dysfunction.

Methylphenidate fails to improve gait and muscle tone in patients with sporadic and hereditary spastic paraplegia

Based on its action on multiple neurotransmitters, including dopamine, methylphenidate (MPH) is of growing interest as a possible treatment option for several movement disorders. Of special interest are diseases that share gait disturbance and cognitive decline. Based on a single case observation in a patient with hereditary spastic spinal paraplegia (HSP) in which gait was improved with MPH, we performed an open-label study with a longitudinal follow-up in 22 patients with HSP and its sporadic form (SSP). The patients were treated for 6 months with 60 mg of MPH per day. Computerized gait analysis and different scores were performed at baseline, after 6 weeks, and after 6 months of treatment. Although at 6 weeks, the gait velocity was somewhat improved, the drug failed to show any effect on other gait parameters and had no beneficial effect at all after 6 months. Although MPH is of interest for several movement disorders, our study did not show a beneficial effect.

Intrathecal baclofen normalizes motor strategy for squatting in familial spastic paraplegia: a case study

We aimed to assess whether intrathecal baclofen could alter the motor strategy for squatting of a patient with pure familial spastic paraplegia. Before baclofen injection and two, four and six hours after it, the patient was evaluated as follows: self-report of walking stiffness and movement initiation; muscle tone with the Ashworth scale; and kinematic and electromyographic analysis of the squatting movement using the opto-electronic ELITE system. The patient's subjective improvement and decrease in muscle tone were dramatic after baclofen injection. Kinematic analysis of squatting showed gradual improvement. Before the injection, the movement was performed with loss of trunk verticality, backward shift of the hip, multiphasic ascending phase of the knee angular velocity and dynamic ankle stiffening. After baclofen injection, the movement was made with vertical translation of body segments and monophasic ascending phase of the knee angular velocity. The effect was maximal six hours after the injection. Electromyographic activities showed a non-specific co-contraction pattern before the injection, and a reciprocal pattern two hours after it. Moreover, a physiological anticipatory deactivation of the hamstring muscles appeared two hours after the injection. In this study of a single patient with familial spastic paraplegia, intrathecal baclofen has facilitated the emergence of normal, supraspinally determined movement patterns.

[Objective measures of muscle stiffness in the ankle. Evaluation of the effect of intrathecal injection of baclofen in spastic patients]

This paper presents the objective and quantitative measurement of muscle stiffness described by Rack and Lehmann. This method allows analysis of the pathophysiological mechanism of spasticity and assessment of anti-spastic treatment. This is illustrated by a case report, showing the objective effect of intrathecally administered baclofen in a spastic patient.

A neurophysiological method for the evaluation of motor performance in spastic walking patients

Intrathecal baclofen is at present the best treatment for severe spasticity of various etiologies. In walking patients affected by severe spasticity a careful evaluation of the motor performance is needed for a correct indication for this treatment. The examination should focus on the delicate balance between spasticity and voluntary muscle activation which is crucial for an improvement of motor performance during gait. Seven patients have been neurophysiologically evaluated by the use of a Cibex apparatus measuring torque and movement velocity of the lower limbs simultaneously with static and dynamic recordings of the EMG.

The treatment of spasticity by intrathecal administration of baclofen: a preliminary personal experience

The administration of baclofen, a GABAb agonist, by direct infusion into the CSF by means of a programmable device, may avoid the undesired side effects of the oral administration of both the same and other antispastic drugs while giving a marked reduction of spasticity. The preliminary results on 12 patients show the total efficacy of this procedure in reducing spasticity markedly.

Continuous intrathecal baclofen infusion for spasticity of cerebral origin

OBJECTIVE

To determine if continuous intrathecal baclofen infusion (CIBI) would provide continuous relief of spasticity in patients with spasticity of cerebral origin, especially children with cerebral palsy.

DESIGN

Prospective, unblinded trial, before and after CIBI.

SETTING

Children's Hospital of Pittsburgh (Pa).

PATIENTS

Thirty-seven patients, 5 to 27 years of age, with spasticity of cerebral origin.

INTERVENTION

Continuous intrathecal baclofen infusion for 3 to 48 months.

MAIN OUTCOME MEASURES

Muscle tone, range of motion, upper extremity timed tasks, activities of daily living (ADLs).

RESULTS

Six and 12 months after CIBI, muscle tone was significantly decreased in the upper (P = .04) and lower (P = .001) extremities. There was a significant relationship between baclofen dosage and muscle tone in the upper (P = .02) and lower (P = .001) extremities. Hamstring motion, upper extremity function, and ADLs were significantly improved in 25 patients who were capable of self-care.

CONCLUSION

Spasticity of cerebral origin can be effectively treated with CIBI. Because baclofen dosages can be titrated for the desired clinical response, CIBI is particularly useful for patients who need some spasticity to stand and ambulate.

Voiding dysfunction in patients with spastic paraplegia: urodynamic evaluation and response to continuous intrathecal baclofen

Patients with hereditary spastic paraplegia (HSP), a degenerative central nervous system disorder characterized by progressive lower extremity spasticity, frequently experience symptoms of voiding dysfunction. Urodynamic evaluation of patients with HSP has not been reported, and the etiology of voiding dysfunction remains unexplained. We present our evaluation of three men (ages 42-62 years) with this rare syndrome. Urgency of urination was a uniform and dominant complaint, and two patients regularly experienced urge incontinence. Other symptoms included frequency (n = 3), nocturia (n = 3), and diminished force of stream (n = 1). Postvoid residual volumes were less than 25 ml in all patients. On urodynamic evaluation the two patients with urge incontinence displayed cystometric evidence of involuntary detrusor contractions. Pelvic floor EMG recordings suggested detrusor-sphincter dyssynergia (DSD). In addition, one patient exhibited markedly diminished bladder compliance (1.0 ml/cm H2O) and capacity (50 ml). All patients reported marked symptomatic improvement when treated with continuous intrathecal baclofen. Evaluation during baclofen treatment revealed increases in bladder compliance and capacity, with apparent resolution of DSD in one patient. Voiding symptoms in these patients most likely arise from a neurogenic etiology; however, a contributory role for chronic outlet obstruction from striated muscle spasticity may also exist.

Intrathecal baclofen in hereditary spastic paraparesis

Intrathecal baclofen has not been previously evaluated for the treatment of the disabling hypertonia associated with hereditary spastic paraparesis. Muscle tone and deep-tendon reflexes were evaluated in three patients with hereditary spastic paraparesis after a double-blind, cross-over bolus injection of intrathecal baclofen. Patients underwent placement of a subcutaneous pump for continuous infusion of intrathecal baclofen. Three months after implantation the muscle tone decreased 2.04 points (p less than .0001) and the reflex score decreased 2.25 points (p less than .001). Patients initially reported subjective weakness, but muscle testing revealed either an increase or no change in voluntary motor function. Baclofen doses of 60 to 264 micrograms per day were required for effective control of muscle tone and spasticity. Much of the disability in familial spastic paraparesis may be related to the loss of suprasegmental inhibition of spinal reflexes overwhelming the residual voluntary motor function.

L-threonine in the treatment of spasticity

Preclinical data indicate that the administration of the amino acid L-threonine increases glycine levels in rat spinal cord. In order to investigate glycinergic mechanisms in spasticity, and other signs of the upper motor syndrome, we gave 4.5 and 6.0 g/day of L-threonine to 18 patients with familial spastic paraparesis (FSP) according to a double-blind, crossover protocol. The response to treatment at the end of each 2-week period was based upon three measures: the physician's global impressions; the patients' global impressions; and semiquantitative ratings of strength, muscle tone, DTRs, walking, hopping, and running. Blood and CSF were collected during each treatment period for amino acid analyses. Based upon the severity rating scales, there was a statistically significant (p less than 0.02) decrease in motor impairment and spasticity during L-threonine administration compared to placebo treatment; significant treatment effects were not found on the physician's and patients' global impressions. Plasma and CSF levels of threonine increased significantly during L-threonine treatment but glycine levels did not change. These data indicate that L-threonine significantly suppressed the signs of spasticity even though the benefits were not clinically valuable.