Identification of a cytokine profile in serum and cerebrospinal fluid of pediatric and adult spinal muscular atrophy patients and its modulation upon nusinersen treatment

Background and objectives

Multisystem involvement in spinal muscular atrophy (SMA) is gaining prominence since different therapeutic options are emerging, making the way for new SMA phenotypes and consequent challenges in clinical care. Defective immune organs have been found in preclinical models of SMA, suggesting an involvement of the immune system in the disease. However, the immune state in SMA patients has not been investigated so far. Here, we aimed to evaluate the innate and adaptive immunity pattern in SMA type 1 to type 3 patients, before and after nusinersen treatment.

Methods

Twenty one pediatric SMA type 1, 2, and 3 patients and 12 adult SMA type 2 and 3 patients were included in this single-center retrospective study. A Bio-Plex Pro-Human Cytokine 13-plex Immunoassay was used to measure cytokines in serum and cerebrospinal fluid (CSF) of the study cohort before and after 6 months of therapy with nusinersen.

Results

We detected a significant increase in IL-1β, IL-4, IL-6, IL-10, IFN-γ, IL-17A, IL-22, IL-23, IL-31, and IL-33, in serum of pediatric and adult SMA patients at baseline, compared to pediatric reference ranges and to adult healthy controls. Pediatric patients showed also a significant increase in TNF-α and IL-17F levels at baseline. IL-4, IFN-γ, Il-22, IL-23, and IL-33 decreased in serum of pediatric SMA patients after 6 months of therapy when compared to baseline. A significant decrease in IL-4, IL-6, INF-γ, and IL-17A was detected in serum of adult SMA patients after treatment. CSF of both pediatric and adult SMA patients displayed detectable levels of all cytokines with no significant differences after 6 months of treatment with nusinersen. Notably, a higher baseline expression of IL-23 in serum correlated with a worse motor function outcome after treatment in pediatric patients. Moreover, after 6 months of treatment, patients presenting a higher IL-10 concentration in serum showed a better Hammersmith Functional Motor Scale Expanded (HFMSE) score.

Discussion

Pediatric and adult SMA patients show an inflammatory signature in serum that is reduced upon SMN2 modulating treatment, and the presence of inflammatory mediators in CSF. Our findings enhance SMA knowledge with potential clinical and therapeutic implications.

Evaluation of body composition as a potential biomarker in spinal muscular atrophy

INTRODUCTION

We aimed to investigate the correlation between body composition (BC) and spinal muscular atrophy (SMA)-specific motor function assessments.

METHODS

Patients with SMA types I or II, aged 1 to 10 years, were recruited in this cross-sectional study. The protocol included anthropometric measurements, and dual-energy X-ray absoprtiometry to assess fat mass (FM), lean mass (LM), fat-free mass (FFM), FM and FFM indexes (FMI, FFMI), and motor function assessments (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scale for SMAI, and Hammersmith Functional Motor Scale-Expanded for SMAII).

RESULTS

Eighty-eight children were included. All had a higher FM percentage than reference values. Motor function was moderately correlated with body mass index (BMI), FFMI, and LMI in SMAI, and weakly correlated with FFMI, LMI, and LM:FM ratio in SMAII.

DISCUSSION

BC shows promise as a potential biomarker for SMA, but further studies are needed.

Circulating MyomiRs as Potential Biomarkers to Monitor Response to Nusinersen in Pediatric SMA Patients

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by mutations in survival motor neuron (SMN) 1 gene, resulting in a truncated SMN protein responsible for degeneration of brain stem and spinal motor neurons. The paralogous SMN2 gene partially compensates full-length SMN protein production, mitigating the phenotype. Antisense oligonucleotide nusinersen (Spinraza^®) enhances SMN2 gene expression. SMN is involved in RNA metabolism and biogenesis of microRNA (miRNA), key gene expression modulators, whose dysregulation contributes to neuromuscular diseases. They are stable in body fluids and may reflect distinct pathophysiological states, thus acting as promising biomarkers. Muscle-specific miRNAs (myomiRs) as biomarkers for clinical use in SMA have not been investigated yet. Here, we analyzed the expression of miR-133a, -133b, -206 and -1, in serum of 21 infantile SMA patients at baseline and after 6 months of nusinersen treatment, and correlated molecular data with response to therapy evaluated by the Hammersmith Functional Motor Scale Expanded (HFMSE). Our results demonstrate that myomiR serological levels decrease over disease course upon nusinersen treatment. Notably, miR-133a reduction predicted patients’ response to therapy. Our findings identify myomiRs as potential biomarkers to monitor disease progression and therapeutic response in SMA patients.

Outcome measures for children with movement disorders

The huge contribution of advances in the pediatric neurosciences, improvements in clinical practice, and new therapeutic options, has led to the development of new models of treatment and rehabilitation for dystonia in the last decade. It is now generally agreed that a multidimensional therapeutic approach is needed for children with motor disorders, whose motor function-conceived as a complex perceptive, motor and cognitive process - is impaired at a crucial time in their development, with a fall out on how their various adaptive functions evolve. Neurophysiological studies, modern neuroimaging techniques, and advances in cognitive psychology have all contributed to improving our understanding of the potential effects of treatments in early age - not only on the symptoms, but also on plasticity processes and neuronal reorganization. The International Classification of Functioning, Disability and Health (ICF) promoted by the WHO, and the diffusion of family-centered models of healthcare have underscored the importance of the ecological perspective with a view to providing effective therapies and a satisfactory quality of life for dystonic children and their families. The advances made in this area have made it necessary to study and develope more appropriate treatment outcome measures. In the light of these aspects, there is still not enough literature on the generally-accepted, exhaustive dystonia assessment tools. Given these limits, it might be useful to discuss the strengths and weaknesses of the main tools currently used in this setting.

Two single cases treated by a new pseudoelastic upper-limb orthosis for secondary dystonia of the young

The study proposes a new treatment for dystonia based on a dynamic wearable orthosis equipped with metallic materials of non-linear mechanical characteristics. Two boys with upper-limb dystonia were enrolled, as well as six healthy children. Fully-customised devices were made for the patients. They used the orthosis for one month and their performances were evaluated before and after the treatment. The assessment was done with clinical scales (Modified Ashworth Score, Melbourne Upper Limb Assessment, PedsQL), interviews and optoelectronic kinematic analysis. Normal kinematics was obtained from the healthy group for comparison. Kinematic analysis showed modifications in motor patterns for both patients, with increases in the ranges of motion of initially stiff segments, improvements in posture, emergence of multi-joint strategies. Clinical scales did not always show similar trends in the two cases. The changes in control strategies could be linked to the force field dynamically applied by the device and appear to be learnable. This interpretation will be further tested with larger groups and longer treatments.

Revised North Star Ambulatory Assessment for Young Boys with Duchenne Muscular Dystrophy

The advent of therapeutic approaches for Duchenne muscular dystrophy (DMD) has highlighted the need to identify reliable outcome measures for young boys with DMD. The aim of this study was to develop a revised version of the North Star Ambulatory Assessment (NSAA) suitable for boys between the age of 3 and 5 years by identifying age appropriate items and revising the scoring system accordingly. Using the scale in 171 controls between the age of 2.9 and 4.8 years, we identified items that were appropriate at different age points. An item was defined as age appropriate if it was completed, achieving a full score, by at least 85% of the typically developing boys at that age. At 3 years (±3months) there were only 8 items that were age appropriate, at 3 years and 6 months there were 13 items while by the age of 4 years all 17 items were appropriate. A revised version of the scale was developed with items ordered according to the age when they could be reliably performed. The application of the revised version of the scale to data collected in young DMD boys showed that very few of the DMD boys were able to complete with a full score all the age appropriate items. In conclusion, our study suggests that a revised version of the NSAA can be used in boys from the age of 3 years to obtain information on how young DMD boys acquire new abilities and how this correlates with their peers.

Hand function assessment in the first years of life in unilateral cerebral palsy: Correlation with neuroimaging and cortico-spinal reorganization

AIM

The purpose of the present study was to correlate early hand function assessment during the first years of life with neuroimaging findings and the different patterns of cortico-motor reorganization in children with unilateral cerebral palsy (UCP).

METHODS

We conducted a long prospective observational study, in which 17 children with UCP (8 left-sided hemiplegia; Manual Ability Classification System level 1-3) were first assessed at a mean age of 24 months (range 18-28), and followed up by means of the Besta Scale, a new standardized protocol assessing both unimanual and bimanual hand function. They also underwent Melbourne Assessment of Unilateral Upper Limb Function (MUUL) and single-pulse Transcranial Magnetic Stimulation (TMS) at a mean age of 10 years 5 months (range 9 y 1 m-12 y 8 m). Brain MRIs of all the 17 children were independently assessed and scored by two blinded observers, according to a defined protocol. Possible correlations between hand function at first assessment, neuroimaging and TMS data were analyzed.

RESULTS

Early hand function impairment significantly correlated with the extension of brain damage (ρ = -0.531, p = 0.028), number of involved areas (ρ = -0.608, p = 0.010), presence of radiological signs of cortico-spinal degeneration (ρ = -0.628, p = 0.007), and basal ganglia involvement (ρ = -0.485, p = 0.049). Additionally, higher hand function scores (i.e. better hand function) at first assessment significantly correlated with contralateral cortico-spinal projections, while lower scores significantly correlated with either mixed or ipsilateral cortico-spinal projections to the affected hand (χ(2)(2) = 11.418, p = 0.003; post-hoc tests: contralateral TMS group versus ipsilateral: Z = -2.943, p = 0.002 and contralateral TMS group versus mixed: Z = -2.775, p = 0.006).

CONCLUSIONS

To our knowledge, this is the first study correlating hand function assessment in the first years of life, and its evolution over time, with neuroimaging and cortico-spinal projection patterns in children with UCP. These findings could contribute to an improved prediction of prognosis and a better delineation of therapeutic interventions in young children with UCP.

Bone and Spinal Muscular Atrophy

Spinal Muscular Atrophy (SMA) is an autosomal recessive neuromuscular disease, leading to progressive denervation atrophy in the involved skeletal muscles. Bone status has been poorly studied. We assessed bone metabolism, bone mineral density (BMD) and fractures in 30 children (age range 15-171 months) affected by SMA types 2 and 3. Eighteen children (60%) had higher than normal levels of CTx (bone resorption marker); 25-OH vitamin D was in the lower range of normal (below 20 ng/ml in 9 children and below 12 ng/ml in 2). Lumbar spine BMAD (bone mineral apparent density) Z-score was below -1.5 in 50% of children. According to clinical records, four children had sustained four peripheral fractures; on spine X-rays, we observed 9 previously undiagnosed vertebral fractures in 7 children. There was a significant inverse regression between PTH and 25-OH D levels, and a significant regression between BMC and BMAD values and the scores of motor-functional tests. Even if this study could not establish the pathogenesis of bone derangements in SMA, its main findings - reduced bone density, low 25OH vitamin D levels, increased bone resorption markers and asymptomatic vertebral fractures also in very young patients - strongly suggest that even young subjects affected by SMA should be considered at risk of osteopenia and even osteoporosis and fractures.

Long term natural history data in ambulant boys with Duchenne muscular dystrophy: 36-month changes

The 6 minute walk test has been recently chosen as the primary outcome measure in international multicenter clinical trials in Duchenne muscular dystrophy ambulant patients. The aim of the study was to assess the spectrum of changes at 3 years in the individual measures, their correlation with steroid treatment, age and 6 minute walk test values at baseline. Ninety-six patients from 11 centers were assessed at baseline and 12, 24 and 36 months after baseline using the 6 minute walk test and the North Star Ambulatory Assessment. Three boys (3%) lost the ability to perform the 6 minute walk test within 12 months, another 13 between 12 and 24 months (14%) and 11 between 24 and 36 months (12%). The 6 minute walk test showed an average overall decline of -15.8 (SD 77.3) m at 12 months, of -58.9 (SD 125.7) m at 24 months and -104.22 (SD 146.2) m at 36 months. The changes were significantly different in the two baseline age groups and according to the baseline 6 minute walk test values (below and above 350 m) (p<0.001). The changes were also significantly different according to steroid treatment (p = 0.01). Similar findings were found for the North Star Ambulatory Assessment. These are the first 36 month longitudinal data using the 6 minute walk test and North Star Ambulatory Assessment in Duchenne muscular dystrophy. Our findings will help not only to have a better idea of the progression of the disorder but also provide reference data that can be used to compare with the results of the long term extension studies that are becoming available.

A novel homozygous ISPD gene mutation causing phenotype variability in a consanguineous family

Within the group of muscular dystrophies, dystroglycanopathies represent an important subgroup of recessively inherited disorders. Their severity varies from the relatively mild forms of adult-onset limb-girdle muscular dystrophy (LGMD), to the severe congenital muscular dystrophies (CMD) with cerebral and ocular involvement. We describe 2 consanguineous children of Pakistani origin, carrying a new homozygous missense mutation c.367G>A (p.Gly123Arg) in the ISPD gene. Mutations in this gene have been recently reported as a common cause of congenital and limb-girdle muscular dystrophy. Patient 1 is an 8-year-old female with an intermediate phenotype between CMD and early LGMD; patient 2 is a 20-month-old male and second cousin of patient 1, showing a CMD phenotype. Cognitive development, brain MRI, eye examination, electrocardiogram and echocardiogram were normal in both patients. To our knowledge, this is the first report on the co-occurrence of both a CMD/early LGMD intermediate phenotype and a CMD within the same family carrying a homozygous ISPD mutation.

6 Minute walk test in Duchenne MD patients with different mutations: 12 month changes

OBJECTIVE

In the last few years some of the therapeutical approaches for Duchenne muscular dystrophy (DMD) are specifically targeting distinct groups of mutations, such as deletions eligible for skipping of individual exons. The aim of this observational study was to establish whether patients with distinct groups of mutations have different profiles of changes on the 6 minute walk test (6MWT) over a 12 month period.

METHODS

The 6MWT was performed in 191 ambulant DMD boys at baseline and 12 months later. The results were analysed using a test for heterogeneity in order to establish possible differences among different types of mutations (deletions, duplications, point mutations) and among subgroups of deletions eligible to skip individual exons.

RESULTS

At baseline the 6MWD ranged between 180 and 560,80 metres (mean 378,06, SD 74,13). The 12 month changes ranged between -325 and 175 (mean -10.8 meters, SD 69.2). Although boys with duplications had better results than those with the other types of mutations, the difference was not significant. Similarly, boys eligible for skipping of the exon 44 had better baseline results and less drastic changes than those eligible for skipping exon 45 or 53, but the difference was not significant.

CONCLUSIONS

even if there are some differences among subgroups, the mean 12 month changes in each subgroup were all within a narrow Range: from the mean of the whole DMD cohort. This information will be of help at the time of designing clinical trials with small numbers of eligible patients.