Is there an effect of intranasal insulin on development and behaviour in Phelan-McDermid syndrome? A randomized, double-blind, placebo-controlled trial

An overview of in vitro and in vivo techniques for characterization of intranasal protein and peptide formulations for brain targeting

The surge in neurological disorders necessitates innovative strategies for delivering active pharmaceutical ingredients to the brain. The non-invasive intranasal route has emerged as a promising approach to optimize drug delivery to the central nervous system by circumventing the blood-brain barrier. While the intranasal approach offers numerous advantages, the lack of a standardized protocol for drug testing poses challenges to both in vitro and in vivo studies, limiting the accurate interpretation of nasal drug delivery and pharmacokinetic data. This review explores the in vitro experimental assays employed by the pharmaceutical industry to test intranasal formulation. The focus lies on understanding the diverse techniques used to characterize the intranasal delivery of drugs targeting the brain. Parameters such as drug release, droplet size measurement, plume geometry, deposition in the nasal cavity, aerodynamic performance and mucoadhesiveness are scrutinized for their role in evaluating the performance of nasal drug products. The review further discusses the methodology for in vivo characterization in detail, which is essential in evaluating and refining drug efficacy through the nose-to-brain pathway. Animal models are indispensable for pre-clinical drug testing, offering valuable insights into absorption efficacy and potential variables affecting formulation safety. The insights presented aim to guide future research in intranasal drug delivery for neurological disorders, ensuring more accurate predictions of therapeutic efficacy in clinical contexts.

Caregiver perspectives on patient-focused drug development for Phelan-McDermid syndrome

BACKGROUND

Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder caused by SHANK3 haploinsufficiency with clinical manifestations that can be devastating and profoundly affect quality of life.

RESULTS

The Externally Led Patient-Focused Drug Development (EL-PFDD) meeting was an opportunity for families affected by PMS to share with the Food and Drug Administration (FDA) how symptoms impact their lives and how treatments could be most meaningful. The Voice of the Patient report serves as a summary of this meeting to influence upcoming drug development and clinical trials. The purpose of this report is to provide a clinical perspective on the results of the EL-PFDD meeting to amplify the voice of these caregivers to the scientific community.

CONCLUSIONS

Caregivers prioritize an improved quality of life for their loved ones characterized by improved cognitive function, improved communication, increased independence, and reduced risk of regression. With these caregiver priorities in mind, this report provides the FDA and the scientific community with a clear understanding of which aspects of PMS should influence the development of future therapeutics.

The role of insulin/IGF1 signalling in neurodevelopmental and neuropsychiatric disorders - Evidence from human neuronal cell models

Insulin and insulin-like growth factor 1 (IGF1) signalling play a central role in the development and maintenance of neurons in the brain, and human neurodevelopmental as well as neuropsychiatric disorders have been linked to impaired insulin and IGF1 signalling. This review focuses on the impairments of the insulin and IGF1 signalling cascade in the context of neurodevelopmental and neuropsychiatric disorders, based on evidence from human neuronal cell models. Clear evidence was obtained for impaired insulin and IGF1 receptor downstream signalling in neurodevelopmental disorders, while the evidence for its role in neuropsychiatric disorders was less substantial. Human neuronal model systems can greatly add to our knowledge about insulin/IGF1 signalling in the brain, its role in restoring dendritic maturity, and complement results from clinical studies and animal models. Moreover, they represent a useful model for the development of new therapeutic strategies. Further research is needed to systematically investigate the exact role of the insulin/IGF1 signalling cascades in neurodevelopmental and neuropsychiatric disorders, and to elucidate the respective therapeutic implications.

Updated consensus guidelines on the management of Phelan-McDermid syndrome

Phelan-McDermid syndrome (PMS) is a genetic condition caused by SHANK3 haploinsufficiency and characterized by a wide range of neurodevelopmental and systemic manifestations. The first practice parameters for assessment and monitoring in individuals with PMS were published in 2014; recently, knowledge about PMS has grown significantly based on data from longitudinal phenotyping studies and large-scale genotype-phenotype investigations. The objective of these updated clinical management guidelines was to: (1) reflect the latest in knowledge in PMS and (2) provide guidance for clinicians, researchers, and the general community. A taskforce was established with clinical experts in PMS and representatives from the parent community. Experts joined subgroups based on their areas of specialty, including genetics, neurology, neurodevelopment, gastroenterology, primary care, physiatry, nephrology, endocrinology, cardiology, gynecology, and dentistry. Taskforce members convened regularly between 2021 and 2022 and produced specialty-specific guidelines based on iterative feedback and discussion. Taskforce leaders then established consensus within their respective specialty group and harmonized the guidelines. The knowledge gained over the past decade allows for improved guidelines to assess and monitor individuals with PMS. Since there is limited evidence specific to PMS, intervention mostly follows general guidelines for treating individuals with developmental disorders. Significant evidence has been amassed to guide the management of comorbid neuropsychiatric conditions in PMS, albeit mainly from caregiver report and the experience of clinical experts. These updated consensus guidelines on the management of PMS represent an advance for the field and will improve care in the community. Several areas for future research are also highlighted and will contribute to subsequent updates with more refined and specific recommendations as new knowledge accumulates.

Outcomes and clinical implications of intranasal insulin on cognition in humans: A systematic review and meta-analysis

BACKGROUND

Aberrant brain insulin signaling has been posited to lie at the crossroads of several metabolic and cognitive disorders. Intranasal insulin (INI) is a non-invasive approach that allows investigation and modulation of insulin signaling in the brain while limiting peripheral side effects.

OBJECTIVES

The objective of this systematic review and meta-analysis is to evaluate the effects of INI on cognition in diverse patient populations and healthy individuals.

METHODS

MEDLINE, EMBASE, PsycINFO, and Cochrane CENTRAL were systematically searched from 2000 to July 2021. Eligible studies were randomized controlled trials that studied the effects of INI on cognition. Two independent reviewers determined study eligibility and extracted relevant descriptive and outcome data.

RESULTS

Twenty-nine studies (pooled N = 1,726) in healthy individuals as well as those with Alzheimer's disease (AD)/mild cognitive impairment (MCI), mental health disorders, metabolic disorders, among others, were included in the quantitative meta-analysis. Patients with AD/MCI treated with INI were more likely to show an improvement in global cognition (SMD = 0.22, 95% CI: 0.05-0.38 p = <0.00001, N = 12 studies). Among studies with healthy individuals and other patient populations, no significant effects of INI were found for global cognition.

CONCLUSIONS

This review demonstrates that INI may be associated with pro-cognitive benefits for global cognition, specifically for individuals with AD/MCI. Further studies are required to better understand the neurobiological mechanisms and differences in etiology to dissect the intrinsic and extrinsic factors contributing to the treatment response of INI.

Stratification of a Phelan-McDermid Syndrome Population Based on Their Response to Human Growth Hormone and Insulin-like Growth Factor

Phelan-McDermid syndrome (PMS), caused by pathogenic variants in the SHANK3 gene or 22q13 deletions, is characterized by intellectual disability, autistic features, developmental delays, and neonatal hypotonia. Insulin-like growth factor 1 (IGF-1) and human growth hormone (hGH) have been shown to reverse neurobehavioral deficits in PMS. We assessed the metabolic profiling of 48 individuals with PMS and 50 controls and determined subpopulations by taking the top and bottom 25% of responders to hGH and IGF-1. A distinct metabolic profile for individuals with PMS showed a reduced ability to metabolize major energy sources and a higher metabolism of alternative energy sources. The analysis of the metabolic response to hGH or IGF-1 highlighted a major overlap between both high and low responders, validating the model and suggesting that the two growth factors share many target pathways. When we investigated the effect of hGH and IGF-1 on the metabolism of glucose, the correlation between the high-responder subgroups showed less similarity, whereas the low-responders were still relatively similar. Classification of individuals with PMS into subgroups based on responses to a compound can allow an investigation into pathogenic mechanisms, the identification of molecular biomarkers, an exploration of in vitro responses to candidate drugs, and eventually the selection of better candidates for clinical trials.

"Your Life Turns Upside Down": A Qualitative Study of the Experiences of Parents with Children Diagnosed with Phelan-McDermid Syndrome

(1) Background: Parents of children with rare diseases experience great uncertainty and employ different strategies to care for their children and cope with the disease. The purpose of the present study was to describe the perspective of parents with children with Phelan McDermid Syndrome (PMS). (2) Methods: A non-probabilistic purposeful sampling was used to perform this qualitative descriptive study. Thirty-two parents with children with PMS were interviewed. In-depth interviews and research field notes were analyzed using an inductive thematic analysis. (3) Results: Four themes emerged from the data. "Understanding and accepting the disease" described how parents experienced their child's diagnosis and the lack of information. The second theme, called "Living day by day", highlighted the daily difficulties faced when caring for a child with PMS. The third theme, "Expectations versus reality", was based on the parents' expectations of parenthood and the reality they face. Expectations for the future are also included. Finally, "Pain and happiness" describes how parents alternate feelings of distress and suffering but also joy with what they learn from these experiences. (4) Conclusions: Health professionals can use these results to support parents.

Intranasal Peptide Therapeutics: A Promising Avenue for Overcoming the Challenges of Traditional CNS Drug Development

The central nervous system (CNS) has, among all organ systems in the human body, the highest failure rate of traditional small-molecule drug development, ranging from 80-100% depending on the area of disease research. This has led to widespread abandonment by the pharmaceutical industry of research and development for CNS disorders, despite increased diagnoses of neurodegenerative disorders and the continued lack of adequate treatment options for brain injuries, stroke, neurodevelopmental disorders, and neuropsychiatric illness. However, new approaches, concurrent with the development of sophisticated bioinformatic and genomic tools, are being used to explore peptide-based therapeutics to manipulate endogenous pathways and targets, including "undruggable" intracellular protein-protein interactions (PPIs). The development of peptide-based therapeutics was previously rejected due to systemic off-target effects and poor bioavailability arising from traditional oral and systemic delivery methods. However, targeted nose-to-brain, or intranasal (IN), approaches have begun to emerge that allow CNS-specific delivery of therapeutics via the trigeminal and olfactory nerve pathways, laying the foundation for improved alternatives to systemic drug delivery. Here we review a dozen promising IN peptide therapeutics in preclinical and clinical development for neurodegenerative (Alzheimer's, Parkinson's), neuropsychiatric (depression, PTSD, schizophrenia), and neurodevelopmental disorders (autism), with insulin, NAP (davunetide), IGF-1, PACAP, NPY, oxytocin, and GLP-1 agonists prominent among them.

Sleep and Phelan-McDermid Syndrome: Lessons from the International Registry and the scientific literature

Background

Sleep is essential to maintaining a healthy life. Sleep disturbances among individuals with neurodevelopmental disorders are not well studied, affecting their early detection and treatment. Sleep disturbances in individuals with Phelan–McDermid Syndrome (PMS) are among the primary concerns reported by parents. However, little research has been aimed at addressing their concern.

Methods

The purpose of this investigation was to identify and quantify specific sleep disturbances in people with PMS by analyzing data collected by the PMS Foundation International Registry.

Results

The registry shows that 284 out of 384 (73.4%) individuals with confirmed chromosome 22q13 deletions or SHANK3 pathogenic variants have a sleep disturbance. The prevalence of sleep disturbances increases with age with 56% reporting a sleep disturbance in the 0–3 year age group and 90% reporting these disturbances in those over age 18 years old. The primary sleep disturbances were circadian rhythm sleep disorders that included difficulty falling asleep, frequent nighttime awakenings, difficulty returning to sleep after a nighttime awakening event, and hypersomnia and parasomnias including enuresis, night terrors, sleepwalking, and sleep apnea. Sleep disturbances were similarly frequent among individuals with SHANK3 pathogenic variants (84.8%) and those with deletions (71.9%), supporting the role of haploinsufficiency of SHANK3 in sleep.

Conclusion

Sleep disturbances are a common feature of PMS and should be considered in clinical evaluation and management because of the effect they have on the quality of life of the patients and their families.

Clinical and Genetic Aspects of Phelan–McDermid Syndrome: An Interdisciplinary Approach to Management

Phelan–McDermid syndrome (PMS) is a rare, heterogeneous, and complex neurodevelopmental disorder. It is generally caused by a heterozygous microdeletion of contiguous genes located in the distal portion of the long arm of chromosome 22, including the SHANK3 gene. Sequence variants of SHANK3, including frameshift, nonsense mutations, small indels and splice site mutations also result in PMS. Furthermore, haploinsufficiency in SHANK3 has been suggested as the main cause of PMS. SHANK3 is also associated with intellectual disability, autism spectrum disorder and schizophrenia. The phenotype of PMS is variable, and lacks a distinctive phenotypic characteristic, so the clinical diagnosis should be confirmed by genetic analysis. PMS is a multi-system disorder, and clinical care must encompass various specialties and therapists. The role of risperidone, intranasal insulin, insulin growth factor 1, and oxytocin as potential therapeutic options in PMS will be discussed in this review. The diagnosis of PMS is important to provide an appropriate clinical evaluation, treatment, and genetic counseling.

Comparison of SHANK3 deficiency in animal models: phenotypes, treatment strategies, and translational implications

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental condition, which is characterized by clinical heterogeneity and high heritability. Core symptoms of ASD include deficits in social communication and interaction, as well as restricted, repetitive patterns of behavior, interests, or activities. Many genes have been identified that are associated with an increased risk for ASD. Proteins encoded by these ASD risk genes are often involved in processes related to fetal brain development, chromatin modification and regulation of gene expression in general, as well as the structural and functional integrity of synapses. Genes of the SH3 and multiple ankyrin repeat domains (SHANK) family encode crucial scaffolding proteins (SHANK1-3) of excitatory synapses and other macromolecular complexes. SHANK gene mutations are highly associated with ASD and more specifically the Phelan-McDermid syndrome (PMDS), which is caused by heterozygous 22q13.3-deletion resulting in SHANK3-haploinsufficiency, or by SHANK3 missense variants. SHANK3 deficiency and potential treatment options have been extensively studied in animal models, especially in mice, but also in rats and non-human primates. However, few of the proposed therapeutic strategies have translated into clinical practice yet.

MAIN TEXT

This review summarizes the literature concerning SHANK3-deficient animal models. In particular, the structural, behavioral, and neurological abnormalities are described and compared, providing a broad and comprehensive overview. Additionally, the underlying pathophysiologies and possible treatments that have been investigated in these models are discussed and evaluated with respect to their effect on ASD- or PMDS-associated phenotypes.

CONCLUSIONS

Animal models of SHANK3 deficiency generated by various genetic strategies, which determine the composition of the residual SHANK3-isoforms and affected cell types, show phenotypes resembling ASD and PMDS. The phenotypic heterogeneity across multiple models and studies resembles the variation of clinical severity in human ASD and PMDS patients. Multiple therapeutic strategies have been proposed and tested in animal models, which might lead to translational implications for human patients with ASD and/or PMDS. Future studies should explore the effects of new therapeutic approaches that target genetic haploinsufficiency, like CRISPR-mediated activation of promotors.

Genetic Findings as the Potential Basis of Personalized Pharmacotherapy in Phelan-McDermid Syndrome

Phelan-McDermid syndrome (PMS) is a genetic disorder often characterized by autism or autistic-like behavior. Most cases are associated with haploinsufficiency of the SHANK3 gene resulting from deletion of the gene at 22q13.3 or from a pathogenic variant in the gene. Treatment of PMS often targets SHANK3, yet deletion size varies from <50 kb to >9 Mb, potentially encompassing dozens of genes and disrupting regulatory elements altering gene expression, inferring the potential for multiple therapeutic targets. Repurposed drugs have been used in clinical trials investigating therapies for PMS: insulin-like growth factor 1 (IGF-1) for its effect on social and aberrant behaviors, intranasal insulin for improvements in cognitive and social ability, and lithium for reversing regression and stabilizing behavior. The pharmacogenomics of PMS is complicated by the CYP2D6 enzyme which metabolizes antidepressants and antipsychotics often used for treatment. The gene coding for CYP2D6 maps to 22q13.2 and is lost in individuals with deletions larger than 8 Mb. Because PMS has diverse neurological and medical symptoms, many concurrent medications may be prescribed, increasing the risk for adverse drug reactions. At present, there is no single best treatment for PMS. Approaches to therapy are necessarily complex and must target variable behavioral and physical symptoms of PMS.

Opportunities for ABA intervention in Phelan-McDermid syndrome

Phelan-McDermid syndrome (PMS), also called 22q13.3 deletion syndrome, is a rare genetic disorder affecting at least 2,000 people worldwide (Phelan-McDermid Syndrome Foundation, 2019, How rare is Phelan-McDermid?). PMS has many distinguishing characteristics and many medical specialties have been recommended to treat the clinical features. While many therapies, including behavioral therapy, have been speculated to be beneficial in treating PMS, there is little known regarding their effectiveness [Costales, J. L. and Kolevzon, A. 2015. Phelan-McDermid syndrome and SHANK3: Implications for treatment. Neurotherapeutics: The Journal of the American Society for Experimental Neurotherapeutics, 12, 620-630.]. Behavior analysis has the capability to help in many areas of treatment for PMS either directly through, for example, behavior treatment to address aggressive behavior, or through collaborating with other specialties treating PMS by combining, for example, behavioral principles in the alleviation of medical issues such as constipation. Currently, there is a role for the behavior analyst to expand our field and identify effective treatments for those with PMS while we wait for a cure. In this paper, we discuss how medical considerations may affect behavior interventions and make recommendations for the behavior analyst working with PMS.

Non-Invasive Strategies for Nose-to-Brain Drug Delivery

Intranasal drug administration is a promising method for delivering drugs directly to the brain. Animal studies have described pathways and potential brain targets, but nose-to-brain delivery and treatment efficacy in humans remains debated. We describe the proposed pathways and barriers for nose-to-brain drug delivery in humans, drug properties that influence central nervous system delivery, clinically tested methods to enhance absorption, and the devices used in clinical trials. This review compiles the available evidence for nose-to-brain drug delivery in humans and summarizes the factors involved in nose-to-brain drug delivery.

Molecular mechanisms for targeted ASD treatments

The possibility to generate construct valid animal models enabled the development and testing of therapeutic strategies targeting the core features of autism spectrum disorders (ASDs). At the same time, these studies highlighted the necessity of identifying sensitive developmental time windows for successful therapeutic interventions. Animal and human studies also uncovered the possibility to stratify the variety of ASDs in molecularly distinct subgroups, potentially facilitating effective treatment design. Here, we focus on the molecular pathways emerging as commonly affected by mutations in diverse ASD-risk genes, on their role during critical windows of brain development and the potential treatments targeting these biological processes.

SULT4A1 Modulates Synaptic Development and Function by Promoting the Formation of PSD-95/NMDAR Complex

Sulfotransferase 4A1 (SULT4A1) is a cytosolic sulfotransferase that is highly conserved across species and extensively expressed in the brain. However, the biological function of SULT4A1 is unclear. SULT4A1 has been implicated in several neuropsychiatric disorders, such as Phelan-McDermid syndrome and schizophrenia. Here, we investigate the role of SULT4A1 within neuron development and function. Our data demonstrate that SULT4A1 modulates neuronal branching complexity and dendritic spines formation. Moreover, we show that SULT4A1, by negatively regulating the catalytic activity of Pin1 toward PSD-95, facilitates NMDAR synaptic expression and function. Finally, we demonstrate that the pharmacological inhibition of Pin1 reverses the pathologic phenotypes of neurons knocked down by SULT4A1 by specifically restoring dendritic spine density and rescuing NMDAR-mediated synaptic transmission. Together, these findings identify SULT4A1 as a novel player in neuron development and function by modulating dendritic morphology and synaptic activity.SIGNIFICANCE STATEMENT Sulfotransferase 4A1 (SULT4A1) is a brain-specific sulfotransferase highly expressed in neurons. Different evidence has suggested that SULT4A1 has an important role in neuronal function and that SULT4A1 altered expression might represent a contributing factor in multiple neurodevelopmental disorders. However, the function of SULT4A1 in the mammalian brain is still unclear. Here, we demonstrate that SULT4A1 is highly expressed at postsynaptic sites where it sequesters Pin1, preventing its negative action on synaptic transmission. This study reveals a novel role of SULT4A1 in the modulation of NMDA receptor activity and strongly contributes to explaining the neuronal dysfunction observed in patients carrying deletions of SULTA41 gene.

A longitudinal perspective on the pharmacotherapy of 24 adult patients with Phelan McDermid syndrome

Over the past years, 24 patients with Phelan-McDermid syndrome were carefully investigated with respect to history, somatic and neurologic antecedents, treatment history, behavioural issues, and psychiatric symptoms including possible catatonic features and regression phenomena. Patients were originally referred for specialized diagnosis and treatment advice because of recurrent challenging behaviours along with instable mood. In all, standardized neuropsychiatric examination was performed including assessment of intellectual and adaptive functioning as well as communication and behaviour concerns. Psychiatric diagnoses were actualized in interdisciplinary consultation meetings according to ICD-10 guidelines. The course of disease was periodically monitored with respect to treatment efficacy and psychopathology over a period varying from one to five years. In 18 patients, a deletion encompassing part of or the entire SHANK3 gene was found. All comprised two or more genes in addition to SHANK3. In six patients, a pathogenic variant in this gene was detected. The psychopathological profile of all patients (nine were published before) was characterized by symptoms from the autism and schizoaffective spectrum while in five, periodic catatonic symptoms were also established. In their third decade, four patients with the deletion subtype developed a regression-like gradual decline of functioning. Based on actual psychiatric classification, in 18 patients, a diagnosis of atypical bipolar disorder was established of which symptoms typically started from late adolescence onward. In most patients, treatment with mood stabilizing agents in combination with individually designed contextual measures, and if indicated with the addition of an atypical antipsychotic, resulted in gradual stabilization of mood and behaviour.

Phelan-McDermid syndrome data network: Integrating patient reported outcomes with clinical notes and curated genetic reports

The heterogeneity of patient phenotype data are an impediment to the research into the origins and progression of neuropsychiatric disorders. This difficulty is compounded in the case of rare disorders such as Phelan-McDermid Syndrome (PMS) by the paucity of patient clinical data. PMS is a rare syndromic genetic cause of autism and intellectual deficiency. In this paper, we describe the Phelan-McDermid Syndrome Data Network (PMS_DN), a platform that facilitates research into phenotype-genotype correlation and progression of PMS by: a) integrating knowledge of patient phenotypes extracted from Patient Reported Outcomes (PRO) data and clinical notes-two heterogeneous, underutilized sources of knowledge about patient phenotypes-with curated genetic information from the same patient cohort and b) making this integrated knowledge, along with a suite of statistical tools, available free of charge to authorized investigators on a Web portal https://pmsdn.hms.harvard.edu. PMS_DN is a Patient Centric Outcomes Research Initiative (PCORI) where patients and their families are involved in all aspects of the management of patient data in driving research into PMS. To foster collaborative research, PMS_DN also makes patient aggregates from this knowledge available to authorized investigators using distributed research networks such as the PCORnet PopMedNet. PMS_DN is hosted on a scalable cloud based environment and complies with all patient data privacy regulations. As of October 31, 2016, PMS_DN integrates high-quality knowledge extracted from the clinical notes of 112 patients and curated genetic reports of 176 patients with preprocessed PRO data from 415 patients.

Insulin receptor in the brain: Mechanisms of activation and the role in the CNS pathology and treatment

While the insulin receptor (IR) was found in the CNS decades ago, the brain was long considered to be an insulin-insensitive organ. This view is currently revisited, given emerging evidence of critical roles of IR-mediated signaling in development, neuroprotection, metabolism, and plasticity in the brain. These diverse cellular and physiological IR activities are distinct from metabolic IR functions in peripheral tissues, thus highlighting region specificity of IR properties. This particularly concerns the fact that two IR isoforms, A and B, are predominantly expressed in either the brain or peripheral tissues, respectively, and neurons express exclusively IR-A. Intriguingly, in comparison with IR-B, IR-A displays high binding affinity and is also activated by low concentrations of insulin-like growth factor-2 (IGF-2), a regulator of neuronal plasticity, whose dysregulation is associated with neuropathologic processes. Deficiencies in IR activation, insulin availability, and downstream IR-related mechanisms may result in aberrant IR-mediated functions and, subsequently, a broad range of brain disorders, including neurodevelopmental syndromes, neoplasms, neurodegenerative conditions, and depression. Here, we discuss findings on the brain-specific features of IR-mediated signaling with focus on mechanisms of primary receptor activation and their roles in the neuropathology. We aimed to uncover the remaining gaps in current knowledge on IR physiology and highlight new therapies targeting IR, such as IR sensitizers.

Safety of intranasal human insulin: A review

AIMS

To conduct a review in order to assess the safety of intranasal human insulin in clinical studies as well as the temporal stability of nasal insulin sprays.

MATERIAL AND METHODS

An electronic search was performed using MEDLINE. We selected original research on intranasal human insulin without further additives in humans. The studies included could be of any design as long as they used human intranasal insulin as their study product. All outcomes and adverse side effects were extracted.

RESULTS

A total of 38 studies in 1092 individuals receiving acute human intranasal insulin treatment and 18 studies in 832 individuals receiving human intranasal insulin treatment lasting between 21 days and 9.7 years were identified. No cases of symptomatic hypoglycaemia or severe adverse events (AEs) were reported. Transient local side effects in the nasal area were frequently experienced after intranasal insulin and placebo spray, while other AEs were less commonly reported. There were no reports of participants being excluded as a result of AEs. No instances of temporal stability of nasal insulin were reported in the literature. Tests on insulin that had been repacked into spray flasks showed that it had a chemical stability of up to 57 days.

CONCLUSIONS

Our retrospective review of published studies on intranasal insulin did not reveal any safety concerns; however, there were insufficient data to ensure the long-term safety of this method of chronic insulin administration. Improved insulin preparations that cause less nasal irritation would be desirable for future treatment.

Pharmacokinetics of Intranasal versus Subcutaneous Insulin in the Mouse

Insulin delivery to the brain has emerged as an important therapeutic target for cognitive disorders associated with abnormal brain energy metabolism. Although insulin is transported across the blood-brain barrier, peripheral routes of administration are problematic due to systemic effects of insulin on blood glucose. Intranasal (IN) administration is being investigated as an alternative route. We conducted a head-to-head comparison of subcutaneous (SC) and IN insulin, assessing plasma and brain pharmacokinetics and blood glucose levels in the mouse. SC insulin (2.4 IU) achieved therapeutically relevant concentrations in the brain (AUCbrain = 2537 h·μIU/mL) but dramatically increased plasma insulin (AUCplasma = 520 351 h·*μIU/mL), resulting in severe hypoglycemia and in some cases death. IN administration of the same dose resulted in similar insulin levels in the brain (AUCbrain = 3442 h·μIU/mL) but substantially lower plasma concentrations (AUCplasma = 354 h·μIU/mL), amounting to a ∼ 2000-fold increase in the AUCbrain:plasma ratio relative to SC. IN dosing also had no significant effect on blood glucose. When administered daily for 9 days, IN insulin increased brain glucose and energy metabolite concentrations (e.g., adenosine triphosphate and phosphocreatine) without causing overt toxicity, suggesting that IN insulin may be a safe therapeutic option for cognitively impaired patients.

Identification of 22q13 genes most likely to contribute to Phelan McDermid syndrome

Chromosome 22q13.3 deletion (Phelan McDermid) syndrome (PMS) is a rare genetic neurodevelopmental disorder resulting from deletions or other genetic variants on distal 22q. Pathological variants of the SHANK3 gene have been identified, but terminal chromosomal deletions including SHANK3 are most common. Terminal deletions disrupt up to 108 protein-coding genes. The impact of these losses is highly variable and includes both significantly impairing neurodevelopmental and somatic manifestations. The current review combines two metrics, prevalence of gene loss and predicted loss pathogenicity, to identify likely contributors to phenotypic expression. These genes are grouped according to function as follows: molecular signaling at glutamate synapses, phenotypes involving neuropsychiatric disorders, involvement in multicellular organization, cerebellar development and functioning, and mitochondrial. The likely most impactful genes are reviewed to provide information for future clinical and translational investigations.