Characterization of the Pharmacokinetic and Pharmacodynamic Profile of Apraglutide, a Glucagon-Like Peptide-2 Analog, in Healthy Volunteers.

Apraglutide (FE 203799) is a glucagon-like peptide-2 (GLP-2) analog under development for the treatment of intestinal failure associated with short bowel syndrome (SBS-IF) and graft-versus-host disease (GvHD). Compared with native GLP-2, apraglutide has slower absorption, reduced clearance, and higher protein binding, enabling once-weekly dosing. This study evaluated the pharmacokinetic (PK) and pharmacodynamic (PD) profile of apraglutide in healthy adults. Healthy volunteers were randomized to receive 6 weekly subcutaneous administrations of 1, 5, or 10 mg apraglutide or placebo. PK and citrulline (an enterocyte mass PD marker) samples were collected at multiple time points. Kinetic parameters of apraglutide and citrulline were calculated using noncompartmental analysis; repeated PD measures were analyzed with a mixed model of covariance. A population PK/PD model was developed that also included data from a previous phase 1 study in healthy volunteers. Twenty-four subjects were randomized; 23 received all study drug administrations. Mean estimated apraglutide clearance was 16.5-20.7 l/day, and mean volume of distribution was 55.4-105.0 liters. A dose-dependent increase in citrulline plasma concentration was observed, with 5-mg and 10-mg doses inducing higher citrulline levels than 1-mg doses and placebo. PK/PD analysis showed that weekly 5-mg apraglutide induced the maximal citrulline response. Increased plasma citrulline levels were sustained for 10-17 days after the final apraglutide administration. Apraglutide displays predictable dose-dependent PK and PD profiles, with a 5-mg dose showing significant PD effects. Results suggest that apraglutide has early and enduring effects on enterocyte mass and supports the continued development of weekly subcutaneous apraglutide for SBS-IF and GvHD patient populations. SIGNIFICANCE STATEMENT: Once-weekly subcutaneous apraglutide results in dose-dependent elevations of plasma citrulline (an enterocyte mass pharmacodynamic marker) with parameters suggesting that apraglutide has lasting effects on enterocyte mass and the potential to provide therapeutic benefits. This is the first report of a model relating glucagon-like peptide-2 (GLP-2) agonism and its effects in intestinal mucosa, affording not only the ability to predict pharmacologic effects of GLP-2 analogs but also the exploration of optimal dosing regimens for this drug class across populations with different body weights.

Local structural connectivity is associated with social cognition in autism spectrum disorder.

The current theory implying local, short-range overconnectivity in autism spectrum disorder, contrasting with long-range underconnectivity, is based on heterogeneous results, on limited data involving functional connectivity studies, on heterogeneous paediatric populations and non-specific methodologies. In this work, we studied short-distance structural connectivity in a homogeneous population of males with high-functioning autism spectrum disorder and used a novel methodology specifically suited for assessing U-shaped short-distance tracts, including a recently developed tractography-based atlas of the superficial white matter fibres. We acquired diffusion-weighted MRI for 58 males (27 subjects with high-functioning autism spectrum disorder and 31 control subjects) and extracted the mean generalized fractional anisotropy of 63 short-distance tracts. Neuropsychological evaluation included Wechsler Adult Intelligence Scale IV (WAIS-IV), Communication Checklist-Adult, Empathy Quotient, Social Responsiveness Scale and Behaviour Rating Inventory of Executive Function-Adult (BRIEF-A). In contradiction with the models of short-range over-connectivity in autism spectrum disorder, we found that patients with autism spectrum disorder had a significantly decreased anatomical connectivity in a component comprising 13 short tracts compared to controls. Specific short-tract atypicalities in temporal lobe and insula were significantly associated with clinical manifestations of autism spectrum disorder such as social awareness, language structure, pragmatic skills and empathy, emphasizing their importance in social dysfunction. Short-range decreased anatomical connectivity may thus be an important substrate of social deficits in autism spectrum disorder, in contrast with current models.

Increased risk of ADHD in families with ASD.

Attention Deficit and Hyperactive Disorder (ADHD) and Autism Spectrum Disorders (ASD) are frequent comorbid neurodevelopmental conditions and the overlap between both disorders remains to be delineated. A more complete understanding of the shared genetic and environmental factors is needed. Using a family-based method, we evaluated the risk of ADHD in a group of relatives with an ASD proband (ASD-) and a group of relatives with an ASD and ADHD proband (ASD+). We enrolled 1245 individuals in the study: 499 probands, their 746 first-degree relatives and 140 controls. We used a multivariate generalized estimating equation (GEE) model, in which the dependent variable was the ADHD diagnosis in the relatives and the independent variable the ASD+ or ASD- in probands. We adjusted for sociodemographic factors (age, sex, IQ) and for the nature of the familial relationship with the affected proband (parent or sibling). Among the probands, there were 287 ASD- and 212 ASD+ individuals. ADHD was more frequent in relatives (19%) than in the control group (7%) (p = 0.001). The risk of ADHD was higher in the ASD+ relatives group than in the ASD- relatives group (GEE model OR 1.58 [95% CI 1.04-2.38], p = 0.032). This result was found in parents (OR 1.96 [95% CI 1.14-3.36], but not in siblings (OR 1.28 [95% CI 0.84-1.94], p = 0.434). Our study provides a representative estimate of the family distribution of ADHD in relatives of ASD probands but supports the modest effect of shared genetic and environmental factors between both disorders.

Pharmacokinetics and Tolerability of a Single Dose of Apraglutide, a Novel, Long-Acting, Synthetic glucagon-like peptide-2 Analog With a Unique Pharmacologic Profile, in Individuals With Impaired Renal Function.

Renal impairment is a common complication in patients with short bowel syndrome with intestinal failure (SBS-IF). Glucagon-like peptide-2 analogs, such as apraglutide, have been developed as a treatment option for SBS-IF. This study assessed the potential for apraglutide overexposure in individuals with severely impaired renal function versus healthy volunteers with normal renal function. In this phase 1, open-label, multicenter, nonrandomized, parallel-group study, a single dose of apraglutide 5 mg was administered subcutaneously to individuals with severely impaired renal function (<30 mL/min/1.73 m2) and healthy volunteers with normal renal function (≥90 mL/min/1.73 m2). Primary pharmacokinetic endpoints were maximum observed concentration (Cmax) and exposure to apraglutide (area under the curve [AUC] from time 0 to infinity [AUCinf], and AUC from time 0 to the last quantifiable concentration [AUClast]). Each group comprised 8 individuals. Results show that patients with severe renal impairment do not have increased apraglutide exposure. Apraglutide achieved a lower Cmax and AUCinf in individuals with severe renal impairment versus those with normal renal function (Cmax = 36.9 vs 59.5 ng/L; AUCinf = 3100 vs 4470 h · ng/mL, respectively). The respective geometric mean ratios were 0.620 and 0.693 for Cmax and AUCinf, and the upper bound of their 90% confidence intervals were <2, indicating patients with severe renal impairment were not overexposed to apraglutide versus those with normal renal function. Adverse events were mild or moderate in severity. Apraglutide does not require dose reduction for any degree of renal impairment and could be used in a broader patient population of renally impaired patients without dose adjustment.

Efficacy and safety of apraglutide in short bowel syndrome with intestinal failure and colon-in-continuity: A multicenter, open-label, metabolic balance study.

BACKGROUND: Apraglutide is a novel long-acting GLP-2 analog in development for short bowel syndrome with intestinal failure (SBS-IF). This multicenter, open-label, phase 2 study in SBS-IF and colon-in-continuity (CiC) investigates the safety and efficacy of apraglutide. METHODS: This was a 52-week phase 2 metabolic balance study (MBS) in 9 adult patients with SBS-IF-CiC receiving once-weekly subcutaneous apraglutide injections. Safety was the primary endpoint. Secondary endpoints included changes in absorption parameters (MBS at baseline, after 4 weeks with stable parenteral support (PS), and 48 weeks), PS needs (48-week PS adjustment period based on monthly 48-h fluid balances) and intestinal morphology and motility (static and cine MRI at baseline and 4, 24 and 48 weeks). RESULTS: PS volume decreased by -4702 mL/week (-52 %; p < 0.001) at week 52. Seven patients (78 %) achieved ≥1 day off PS at week 52. At 4 weeks, fecal output was reduced by 253 g/day (p = 0.013). At 48 weeks, increases in wet weight absorption by 316 g/day (p = 0.039), energy absorption by 1134 kJ/day (p = 0.041) and carbohydrate absorption by 56.1 g/day (p = 0.024) were observed. Moreover, small bowel length increased from 29.7 to 40.7 cm (p = 0.012), duodenal wall thickness increased by 0.8 mm (p = 0.02) and motility in the proximal colon was reduced (p = 0.031). A total of 127 adverse events was reported, which were mostly mild to moderate. CONCLUSION: Apraglutide had an acceptable safety profile and was associated with significant reductions in PS needs and days off PS, improvements in intestinal absorption, and structural and functional intestinal changes in patients with SBS-IF-CiC. CLINICALTRIALS: gov, Number NCT04964986.

LRRK2 protein levels are determined by kinase function and are crucial for kidney and lung homeostasis in mice.

Mutations in leucine-rich repeat kinase 2 (LRRK2) cause late-onset Parkinson's disease (PD), but the underlying pathophysiological mechanisms and the normal function of this large multidomain protein remain speculative. To address the role of this protein in vivo, we generated three different LRRK2 mutant mouse lines. Mice completely lacking the LRRK2 protein (knock-out, KO) showed an early-onset (age 6 weeks) marked increase in number and size of secondary lysosomes in kidney proximal tubule cells and lamellar bodies in lung type II cells. Mice expressing a LRRK2 kinase-dead (KD) mutant from the endogenous locus displayed similar early-onset pathophysiological changes in kidney but not lung. KD mutants had dramatically reduced full-length LRRK2 protein levels in the kidney and this genetic effect was mimicked pharmacologically in wild-type mice treated with a LRRK2-selective kinase inhibitor. Knock-in (KI) mice expressing the G2019S PD-associated mutation that increases LRRK2 kinase activity showed none of the LRRK2 protein level and histopathological changes observed in KD and KO mice. The autophagy marker LC3 remained unchanged but kidney mTOR and TCS2 protein levels decreased in KD and increased in KO and KI mice. Unexpectedly, KO and KI mice suffered from diastolic hypertension opposed to normal blood pressure in KD mice. Our findings demonstrate a role for LRRK2 in kidney and lung physiology and further show that LRRK2 kinase function affects LRRK2 protein steady-state levels thereby altering putative scaffold/GTPase activity. These novel aspects of peripheral LRRK2 biology critically impact ongoing attempts to develop LRRK2 selective kinase inhibitors as therapeutics for PD.

mRNA stability alterations mediated by HuR are necessary to sustain the fast growth of glioma cells.

Regulation of mRNA decay is an important mechanism controlling gene expression. Steady state levels of mRNAs can be markedly altered by changes in the decay rate. The control of mRNA stability depends on sequences in the transcript itself and on RNA-binding proteins that dynamically bind to these sequences. A well characterized sequence motif, which has been shown to be present in many short-lived mRNAs, is the de-stabilizing adenylate/uridylate-rich element (ARE) located at the 3' untranslated region (3'UTR) of mRNAs. HuR is an RNA-binding protein, which binds to AREs and in doing so, increases the half-life and steady state levels of the corresponding mRNA. Using tissue microarray technology, we found that HuR is over-expressed in human gliomas. We also found that there is a change in HuR localization from being solely in the nucleus to being expressed at high levels in the cytosol. Moreover, a positive correlation was found between total HuR levels, cytosolic localization and tumor grade. We also studied the decay rate of several HuR target mRNAs and found that these mRNAs have a slower rate of decay in glioma cell lines than in astrocytes. Finally, we have been able to decrease both the stability and steady state level of these transcripts in glioma cells using an RNA decoy. More importantly, the decoy transfected cells and cells exposed to a HuR inhibitor have reduced cell growth. In addition, pharmacological inhibition of HuR also resulted in glioma cell growth inhibition. In conclusion, our data suggest that post-transcriptional control abnormalities mediated by HuR are necessary to sustain the rapid growth of this devastating type of cancer.

Novel recognition motifs and biological functions of the RNA-binding protein HuD revealed by genome-wide identification of its targets.

HuD is a neuronal ELAV-like RNA-binding protein (RBP) involved in nervous system development, regeneration, and learning and memory. This protein stabilizes mRNAs by binding to AU-rich instability elements (AREs) in their 3' unstranslated regions (3' UTR). To isolate its in vivo targets, messenger ribonucleoprotein (mRNP) complexes containing HuD were first immunoprecipitated from brain extracts and directly bound mRNAs identified by subsequent GST-HuD pull downs and microarray assays. Using the 3' UTR sequences of the most enriched targets and the known sequence restrictions of the HuD ARE-binding site, we discovered three novel recognition motifs. Motifs 2 and 3 are U-rich whereas motif 1 is C-rich. In vitro binding assays indicated that HuD binds motif 3 with the highest affinity, followed by motifs 2 and 1, with less affinity. These motifs were found to be over-represented in brain mRNAs that are upregulated in HuD overexpressor mice, supporting the biological function of these sequences. Gene ontology analyses revealed that HuD targets are enriched in signaling pathways involved in neuronal differentiation and that many of these mRNAs encode other RBPs, translation factors and actin-binding proteins. These findings provide further insights into the post-transcriptional mechanisms by which HuD promotes neural development and synaptic plasticity.

The Montefiore-Einstein Rigidity Scale-Revised (MERS-R): Development, administration, reliability, and validity in child and adult Autism Spectrum Disorder (ASD).

BACKGROUND: Rigidity contributes to severity and functional impairment in autism spectrum disorder (ASD). There is an unmet need for a valid, reliable, and sensitive outcome measure to assess rigidity in ASD. OBJECTIVE: To develop and validate the Montefiore-Einstein Rigidity Scale-Revised (MERS-R) to assess the Behavioral Rigidity Domain (BRD), Cognitive Rigidity Domain (CRD), and Protest Domain (PD). MATERIALS AND METHODS: The MERS-R was administered to 93 individuals with ASD (children and adults, high and low IQ) at baseline, Week 2, and Week 12. Internal consistency was assessed for domain scores, Total Rigidity Composite (TRC = BRD + CRD), and Total Composite (TC = BRD + CRD + PD) with Cronbach's α. Intraclass correlation coefficients (ICCs) assessed test-retest reliability from baseline to weeks 2 and 12. Pearson's correlations assessed the relationship between the MERS-R and age, sex, and IQ. Convergent validity assessed the correlation of MERS-R scores to the Children's Yale-Brown Obsessive-Compulsive Scale-ASD (CY-BOCS-ASD). RESULTS: Good internal consistency was demonstrated for the BRD, PD, TRC and TC (Cronbach's α = 0.83, 0.88, 0.82, and 0.89, respectively) and adequate internal consistency for the CRD (α = .72). Good or excellent test-test reliability was demonstrated over two weeks (ICC: 0.66─.79), and fair or good reliability over 12 weeks (ICC: 0.56-66). MERS-R scores did not differ by age, sex, or IQ (p: 0.16─.99) with the exception that higher PD scores were associated with younger age (correlation = -0.25, p = 0.01). Significant convergent validity was demonstrated between all MERS-R scores and the CY-BOCS-ASD (p < 0.0001). DISCUSSION: The MERS-R demonstrated internal consistency, test-retest reliability, convergent validity and applicability to autistic children and adults of different sexes and IQ levels. It is a valid, sensitive, and reliable instrument to measure behavioral and cognitive rigidity in ASD.

Apraglutide, a novel glucagon-like peptide-2 analog, improves fluid absorption in patients with short bowel syndrome intestinal failure: Findings from a placebo-controlled, randomized phase 2 trial.

BACKGROUND: Treatment with glucagon-like peptide-2 (GLP-2) analogs improve intestinal adaptation in patients with short bowel syndrome-associated intestinal failure (SBS-IF) and may reduce parenteral support requirements. Apraglutide is a novel, long-acting GLP-2 analog designed for once-weekly dosing. This trial investigated the safety and efficacy of apraglutide in patients with SBS-IF. METHODS: In this placebo-controlled, double-blind, randomized, crossover phase 2 trial, eight adults with SBS-IF were treated with once-weekly 5-mg apraglutide doses and placebo for 4 weeks, followed by once-weekly 10-mg apraglutide doses for 4 weeks, with a washout period of 6-10 weeks between treatments. Safety was the primary end point. Secondary end points included changes from baseline in urine volume output compared with placebo, collected for 48 h before and after each treatment period. RESULTS: Common treatment-related adverse events (AEs) were mild to moderate and included polyuria, decreased stoma output, stoma complications, decreased thirst, and edema. No serious AEs were considered to be related to apraglutide treatment. The safety profile was comparable for the lower and higher doses. Treatment with once-weekly 5- and 10-mg apraglutide doses significantly increased urine volume output by an adjusted mean of 714 ml/day (95% CI, 490-939; P < .05) and 795 ml/day (95% CI, 195-1394; P < .05), respectively, compared with placebo, with no significant differences between doses. CONCLUSIONS: Once-weekly apraglutide was well tolerated at both tested doses and significantly increased urine volume output, providing evidence for increased intestinal fluid absorption. A phase 3 trial is underway in adults with SBS-IF.

Apraglutide, a novel once-weekly glucagon-like peptide-2 analog, improves intestinal fluid and energy absorption in patients with short bowel syndrome: An open-label phase 1 and 2 metabolic balance trial.

BACKGROUND: Apraglutide is a novel long-acting glucagon-like peptide-2 (GLP-2) analog designed for once-weekly subcutaneous dosing, with the potential to increase fluid and nutrient absorption by the remnant intestine of patients who have short bowel syndrome (SBS) with intestinal insufficiency (SBS-II) or intestinal failure (SBS-IF). This trial investigated the safety and effects on intestinal absorption of apraglutide in patients with SBS-II and SBS-IF. METHODS: In this open-label, phase 1 and 2 trial, adult patients with SBS-II (n = 4) or SBS-IF (n = 4) and a fecal output of ≥1500 g/day received once-weekly subcutaneous 5 mg apraglutide for 4 weeks. Safety was the primary end point. Secondary end points included change from baseline in intestinal absorption of wet weight (indicative of fluid absorption), electrolytes, and energy (by bomb calorimetry) measured by inpatient metabolic balance studies. RESULTS: Common treatment-related adverse events were decreased gastrointestinal (GI) stoma output (n = 6), stoma complications (n = 6), GI stoma complications (n = 5), nausea (n = 5), flatulence (n = 4), abnormal GI stoma output (n = 4), polyuria (n = 3), and abdominal pain (n = 3). The only treatment-related serious adverse event (experienced in one patient) was abdominal pain. Apraglutide significantly increased wet weight and energy absorption by an adjusted mean of 741 g/day (95% CI, 194 to 1287; P = 0.015) and 1095 kJ/day (95% CI, 196 to 1994; P = 0.024), respectively. Sodium and potassium absorption significantly increased by an adjusted mean of 38 mmol/day (95% CI, 3 to 74; P = 0.039) and 18 mmol/day (95% CI, 4 to 32; P = 0.020), respectively. CONCLUSION: Once-weekly 5 mg apraglutide was well tolerated in patients with SBS-II and SBS-IF and significantly improved the absorption of fluids, electrolytes, and energy.

Safety and target engagement of an oral small-molecule sequestrant in adolescents with autism spectrum disorder: an open-label phase 1b/2a trial.

Autism spectrum disorder (ASD) is defined by hallmark behaviors involving reduced communication and social interaction as well as repetitive activities and restricted interests. ASD represents a broad spectrum, from minimally affected individuals to those requiring intense support, with additional manifestations often including anxiety, irritability/aggression and altered sensory processing. Gastrointestinal (GI) issues are also common in ASD, and studies have identified changes in the gut microbiome of individuals with ASD compared to control populations, complementing recent findings of differences in gut-derived metabolites in feces and circulation. However, a role for the GI tract or microbiome in ASD remains controversial. Here we report that an oral GI-restricted adsorbent (AB-2004) that has affinity for small aromatic or phenolic molecules relieves anxiety-like behaviors that are driven by a gut microbial metabolite in mice. Accordingly, a pilot human study was designed and completed to evaluate the safety of AB-2004 in an open-label, single-cohort, multiple-ascending-dose clinical trial that enrolled 30 adolescents with ASD and GI symptoms in New Zealand and Australia. AB-2004 was shown to have good safety and tolerability across all dose levels, and no drug-related serious adverse events were identified. Significant reductions in specific urinary and plasma levels of gut bacterial metabolites were observed between baseline and end of AB-2004 treatment, demonstrating likely target engagement. Furthermore, we observed improvements in multiple exploratory behavioral endpoints, most significantly in post hoc analysis of anxiety and irritability, as well as GI health, after 8 weeks of treatment. These results from an open-label study (trial registration no. ACTRN12618001956291) suggest that targeting gut-derived metabolites with an oral adsorbent is a safe and well-tolerated approach to improving symptoms associated with ASD, thereby emboldening larger placebo-controlled trials.

A phase 2 clinical trial of a vasopressin V1a receptor antagonist shows improved adaptive behaviors in men with autism spectrum disorder.

There are no approved pharmacological therapies to address the core symptoms of autism spectrum disorder (ASD), namely, persistent deficits in social communication and social interaction and the presence of restricted, repetitive patterns of behaviors, interests, or activities. The neuropeptide vasopressin has been implicated in the regulation of social behaviors, and its modulation has emerged as a therapeutic target for ASD. The phase 2 VANILLA clinical trial reported here evaluated balovaptan, an orally administered selective vasopressin V1a receptor antagonist, in 223 men with ASD and intelligence quotient ≥70. The drug was administered daily for 12 weeks and was compared with placebo. Participants were randomized to placebo (n = 75) or one of three balovaptan dose arms (1.5 mg, n = 32; 4 mg, n = 77; 10 mg, n = 39). Balovaptan treatment was not associated with a change from baseline compared with placebo at 12 weeks in the primary efficacy endpoint (Social Responsiveness Scale, 2nd Edition). However, dose-dependent and clinically meaningful improvements on the Vineland-II Adaptive Behavior Scales composite score were observed for participants treated with balovaptan 4 or 10 mg compared with placebo. This was driven principally by improvements in the Vineland-II socialization and communication scores. Balovaptan was well tolerated across all doses, and no drug-related safety concerns were identified. These results support further study of balovaptan as a potential treatment for the socialization and communication deficits in ASD.

Decreased Cortical Thickness in the Anterior Cingulate Cortex in Adults with Autism.

Autism spectrum disorder (ASD) is a developmental disorder underdiagnosed in adults. To date, no consistent evidence of alterations in brain structure has been reported in adults with ASD and few studies were conducted at that age. We analyzed structural magnetic resonance imaging data from 167 high functioning adults with ASD and 195 controls. We ran our analyses on a discovery (n = 301) and a replication sample (n = 61). The right caudal anterior cingulate cortical thickness was significantly thinner in adults with ASD compared to controls in both the discovery and the replication sample. Our work underlines the relevance of studying the brain anatomy of an adult ASD population.

Patients with autism spectrum disorders display reproducible functional connectivity alterations.

Despite the high clinical burden, little is known about pathophysiology underlying autism spectrum disorder (ASD). Recent resting-state functional magnetic resonance imaging (rs-fMRI) studies have found atypical synchronization of brain activity in ASD. However, no consensus has been reached on the nature and clinical relevance of these alterations. Here, we addressed these questions in four large ASD cohorts. Using rs-fMRI, we identified functional connectivity alterations associated with ASD. We tested for associations of these imaging phenotypes with clinical and demographic factors such as age, sex, medication status, and clinical symptom severity. Our results showed reproducible patterns of ASD-associated functional hyper- and hypoconnectivity. Hypoconnectivity was primarily restricted to sensory-motor regions, whereas hyperconnectivity hubs were predominately located in prefrontal and parietal cortices. Shifts in cortico-cortical between-network connectivity from outside to within the identified regions were shown to be a key driver of these abnormalities. This reproducible pathophysiological phenotype was partially associated with core ASD symptoms related to communication and daily living skills and was not affected by age, sex, or medication status. Although the large effect sizes in standardized cohorts are encouraging with respect to potential application as a treatment and for patient stratification, the moderate link to clinical symptoms and the large overlap with healthy controls currently limit the usability of identified alterations as diagnostic or efficacy readout.

The RNA-binding protein HuD binds acetylcholinesterase mRNA in neurons and regulates its expression after axotomy.

After axotomy, expression of acetylcholinesterase (AChE) is greatly reduced in the superior cervical ganglion (SCG); however, the molecular events involved in this response remain unknown. Here, we first examined AChE mRNA levels in the brain of transgenic mice that overexpress human HuD. Both in situ hybridization and reverse transcription-PCR demonstrated that AChE transcript levels were increased by more than twofold in the hippocampus of HuD transgenic mice. Additionally, direct interaction between the HuD transgene product and AChE mRNA was observed. Next, we examined the role of HuD in regulating AChE expression in intact and axotomized rat SCG neurons. After axotomy of the adult rat SCG neurons, AChE transcript levels decreased by 50 and 85% by the first and fourth day, respectively. In vitro mRNA decay assays indicated that the decrease in AChE mRNA levels resulted from changes in the stability of presynthesized transcripts. A combination of approaches performed using the region that directly encompasses an adenylate and uridylate (AU)-rich element within the AChE 3'-untranslated region demonstrated a decrease in RNA-protein complexes in response to axotomy of the SCG and, specifically, a decrease in HuD binding. After axotomy, HuD transcript and protein levels also decreased. Using a herpes simplex virus construct containing the human HuD sequence to infect SCG neurons in vivo, we found that AChE and GAP-43 mRNA levels were maintained in the SCG after axotomy. Together, the results of this study demonstrate that AChE expression in neurons of the rat SCG is regulated via post-transcriptional mechanisms that involve the AU-rich element and HuD.

Alterations in mossy fiber physiology and GAP-43 expression and function in transgenic mice overexpressing HuD.

HuD is a neuronal RNA-binding protein associated with the stabilization of mRNAs for GAP-43 and other neuronal proteins that are important for nervous system development and learning and memory mechanisms. To better understand the function of this protein, we generated transgenic mice expressing human HuD (HuD-Tg) in adult forebrain neurons. We have previously shown that expression of HuD in adult dentate granule cells results in an abnormal accumulation of GAP-43 mRNA via posttranscriptional mechanisms. Here we show that this mRNA accumulation leads to the ectopic expression of GAP-43 protein in mossy fibers. Electrophysiological analyses of the mossy fiber to CA3 synapse of HuD-Tg mice revealed increases in paired-pulse facilitation (PPF) at short interpulse intervals and no change in long-term potentiation (LTP). Presynaptic calcium transients at the same synapses exhibited faster time constants of decay, suggesting a decrease in the endogenous Ca(2+) buffer capacity of mossy fiber terminals of HuD-Tg mice. Under resting conditions, GAP-43 binds very tightly to calmodulin sequestering it and then releasing it upon PKC-dependent phosphorylation. Therefore, subsequent studies examined the extent of GAP-43 phosphorylation and its association to calmodulin. We found that despite the increased GAP-43 expression in HuD-Tg mice, the levels of PKC-phosphorylated GAP-43 were decreased in these animals. Furthermore, in agreement with the increased proportion of nonphosphorylated GAP-43, HuD-Tg mice showed increased binding of calmodulin to this protein. These results suggest that a significant amount of calmodulin may be trapped in an inactive state, unable to bind free calcium, and activate downstream signaling pathways. In conclusion, we propose that an unregulated expression of HuD disrupts mossy fiber physiology in adult mice in part by altering the expression and phosphorylation of GAP-43 and the amount of free calmodulin available at the synaptic terminal.

RNA-protein interactions and control of mRNA stability in neurons.

In addition to transcription, posttranscriptional mechanisms play a vital role in the control of gene expression. There are multiple levels of posttranscriptional regulation, including mRNA processing, splicing, editing, transport, stability, and translation. Among these, mRNA stability is estimated to control about 5-10% of all human genes. The rate of mRNA decay is regulated by the interaction of cis-acting elements in the transcripts and sequence-specific RNA-binding proteins. One of the most studied cis-acting elements is the AU-rich element (ARE) present in the 3' untranslated region (3'UTR) of several unstable mRNAs. These sequences are targets of many ARE-binding proteins; some of which induce degradation whereas others promote stabilization of the mRNA. Recently, these mechanisms were uncovered in neurons, where they have been associated with different physiological phenomena, from early development and nerve regeneration to learning and memory processes. In this Mini-Review, we briefly discuss the general mechanisms of control of mRNA turnover and present evidence supporting the importance of these mechanisms in the expression of an increasing number of neuronal genes.

Psychiatric Comorbidities and Psychotropic Medication Use in Autism: A Matched Cohort Study with ADHD and General Population Comparator Groups in the United Kingdom.

Psychiatric comorbidities and use of psychotropic medications are common among patients with autism spectrum disorder (ASD). However, most previous research used data from the United States (US) and few studies have compared medication use in ASD to control groups, making contextualization of results difficult. In the United Kingdom (UK), general practitioners play a key role in the management of ASD. We conducted a retrospective, cross-sectional study over calendar year 2015, using primary care data from the UK. We identified a prevalent cohort of ASD cases (n = 10,856) and matched control groups of (a) general population (n = 21,712) and (b) attention deficit hyperactivity disorder (ADHD; n = 7,058) on age, sex and region. We described psychiatric comorbidities, psychotropic medications, and healthcare utilization in all three cohorts. Within the ASD cohort, we used multivariable logistic regression models to explore associations between patient characteristics and the outcomes of: any psychotropic medication, polypharmacy, and number of primary care visits. We used conditional logistic regression to compare the ASD and control groups. Psychiatric comorbidities were recorded for 41.5% of ASD patients; 32.3% received psychotropic medication and 9.8% received polypharmacy. Increased age and all psychiatric comorbidities (except conduct disorder) were associated with treatment use. Males were less likely to receive a treatment than females [Odds ratio (OR) 0.74 (0.66-0.83)]. ASD patients were more likely to take psychotropic medications than the general population [OR 4.91 (4.46-5.40)], but less likely compared to ADHD patients [OR 0.40 (0.37-0.44)]. Overall, rates of medication use in the UK were lower than those previously reported in the US. Autism Research 2018, 11: 1690-1700. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We used electronic medical records from the UK, to describe the amount of psychiatric comorbidities, psychotropic medication use and healthcare resource use in ASD. Around one in three people with ASD were prescribed a psychotropic medication, which was more than the general population, but less than for those with ADHD. Increased age, psychiatric comorbidities and female gender were all independently associated with psychotropic medication use. Rates of medication use in the UK were lower than those previously reported in the US.

Development of a patient-centered conceptual model of the impact of living with autism spectrum disorder.

The aim of this study was to generate a patient-centered conceptual model of the impact of living with autism spectrum disorder, which can be used to support the selection of outcome measures for clinical trials. Following an initial literature review to identify preliminary concepts and inform an interview guide, in-depth face-to-face interviews were conducted with adolescents and adults with autism spectrum disorder (IQ ⩾ 70) (n = 10), as well as parents of children, adolescents, and adults with autism spectrum disorder (IQ ⩾ 70) (n = 26). Data were analyzed using established qualitative research methods. The resultant conceptual model contains three interrelated domains reflecting core symptoms of autism spectrum disorder (communication deficits, socialization deficits, and restrictive, repetitive patterns of behavior), three domains reflecting associated symptoms of autism spectrum disorder (physical, cognitive, and emotional/behavioral), and three domains representing the impacts of living with autism spectrum disorder (impacts on activities of daily living, school/work, and social life). Interview respondents also cited social communication deficits as priority targets for new treatments. The conceptual model provides a patient-centered perspective of relevant concepts of autism spectrum disorder from the perspectives of people with autism spectrum disorder and their parents and offers a valuable tool for identifying valid patient-centered outcome measures for future clinical trials.