Correction of a knock-in mouse model of acrodysostosis with gene therapy using a rAAV9-CAG-human PRKAR1A vector.

Acrodysostosis is a rare skeletal dysplasia caused by loss-of-function mutations in the regulatory subunit of protein kinase A (PRKAR1A). In a knock-in mouse model (PRKAR1Awt/mut) expressing one copy of the recurrent R368X mutation, we tested the effects of a rAAV9-CAG-human PRKR1A (hPRKAR1A) vector intravenously administered at 4 weeks of age. Caudal vertebrae and tibial diaphyses contained 0.52 ± 0.7 and 0.13 ± 0.3 vector genome per cell (VGC), respectively, at 10 weeks of age and 0.22 ± 0.04 and 0.020 ± 0.04 at 16 weeks while renal cortex contained 0.57 ± 0.14 and 0.26 ± 0.05 VGC. Vector-mediated hPRKAR1A expression was found in growth plate chondrocytes, osteoclasts, osteoblasts, and kidney tubular cells. Chondrocyte architecture was restored in the growth plates. Body length, tail length, and body weight were improved in vector treated PRKAR1Awt/mut mice, not the bone length of their limbs. These results provide one of the few proofs for gene therapy efficacy in a mouse model of chondrodysplasia. In addition, the increased urinary cAMP of PRKAR1Awt/mut mice was corrected almost to normal. In conclusion, gene therapy with hPRKAR1A improved skeletal growth and kidney dysfunction, the hallmarks of acrodysostosis in R368X mutated mice and humans.

Low-dose IL-2 in children with recently diagnosed type 1 diabetes: a Phase I/II randomised, double-blind, placebo-controlled, dose-finding study.

AIMS/HYPOTHESIS: Low-dose IL-2 (ld-IL2) selectively activates and expands regulatory T cells (Tregs) and thus has the potential to skew the regulatory/effector T (Treg/Teff) cell balance towards improved regulation. We investigated which low doses of IL-2 would more effectively and safely activate Tregs during a 1 year treatment in children with recently diagnosed type 1 diabetes. METHODS: Dose Finding Study of IL-2 at Ultra-low Dose in Children With Recently Diagnosed Type 1 Diabetes (DF-IL2-Child) was a multicentre, double-blinded, placebo-controlled, dose-finding Phase I/II clinical trial conducted in four centres at university hospitals in France: 24 children (7-14 years old) with type 1 diabetes diagnosed within the previous 3 months were randomly assigned 1:1:1:1 to treatment by a centralised randomisation system, leading to a 7/5/6/6 patient distribution of placebo or IL-2 at doses of 0.125, 0.250 or 0.500 million international units (MIU)/m2, given daily for a 5 day course and then fortnightly for 1 year. A study number was attributed to patients by an investigator unaware of the randomisation list and all participants as well as investigators and staff involved in the study conduct and analyses were blinded to treatments. The primary outcome was change in Tregs, expressed as a percentage of CD4+ T cells at day 5. It pre-specified that a ≥60% increase in Tregs from baseline would identify Treg high responders. RESULTS: There were no serious adverse events. Non-serious adverse events (NSAEs) were transient and mild to moderate. In treated patients vs placebo, the commonest NSAE was injection site reaction (37.9% vs 3.4%), whereas other NSAEs were at the same level (23.3% vs 19.2%). ld-IL2 induced a dose-dependent increase in the mean proportion of Tregs, from 23.9% (95% CI -11.8, 59.6) at the lowest to 77.2% (44.7, 109.8) at the highest dose, which was significantly different from placebo for all dose groups. However, the individual Treg responses to IL-2 were variable and fluctuated over time. Seven patients, all among those treated with the 0.250 and 0.500 MIU m-2 day-1 doses, were Treg high responders. At baseline, they had lower Treg proportions in CD4+ cells than Treg low responders, and serum soluble IL-2 receptor α (sIL-2RA) and vascular endothelial growth factor receptor 2 (VEGFR2) levels predicted the Treg response after the 5 day course. There was no significant change in glycaemic control in any of the dose groups compared with placebo. However, there was an improved maintenance of induced C-peptide production at 1 year in the seven Treg high responders as compared with low responders. CONCLUSIONS/INTERPRETATION: The safety profile at all doses, the dose-dependent effects on Tregs and the observed variability of the Treg response to ld-IL2 in children with newly diagnosed type 1 diabetes call for use of the highest dose in future developments. The better preservation of insulin production in Treg high responders supports the potential of Tregs in regulating autoimmunity in type 1 diabetes, and warrants pursuing the investigation of ld-IL2 for its treatment and prevention. TRIAL REGISTRATION: ClinicalTrials.gov NCT01862120. FUNDING: Assistance Publique-Hôpitaux de Paris, Investissements d'Avenir programme (ANR-11-IDEX-0004-02, LabEx Transimmunom and ANR-16-RHUS-0001, RHU iMAP) and European Research Council Advanced Grant (FP7-IDEAS-ERC-322856, TRiPoD).

XPG and XPF endonucleases trigger chromatin looping and DNA demethylation for accurate expression of activated genes.

Nucleotide excision repair factors, initially characterized as part of DNA repair, have been shown to participate in the transcriptional process in the absence of genotoxic attack. However, their molecular function when recruited at the promoters of activated genes together with the transcription machinery remained obscure. Here we show that the NER factors XPG and XPF are essential for establishing CTCF-dependent chromatin looping between the promoter and terminator of the activated RARß2 gene. Silencing XPG and/or XPF endonucleases, or mutations in their catalytic sites, prevents CTCF recruitment, chromatin loop formation, and optimal transcription of RARß2. We demonstrated that XPG endonuclease promotes DNA breaks and DNA demethylation at promoters allowing the recruitment of CTCF and gene looping, which is further stabilized by XPF. Our results highlight a timely orchestrated activity of the NER factors XPG and XPF in the formation of the active chromatin hub that controls gene expression.

Prenatal loss of father during World War One is predictive of a reduced lifespan in adulthood.

Although early-life stress is known to alter health, its long-term consequences on mortality remain largely unknown. Thanks to unique French legislation established in 1917 for war orphans and children of disabled soldiers, we were able to study the adult mortality of individuals born in 1914-1916 whose fathers were killed during World War 1. Vital information and socio-demographic characteristics were extracted manually from historical civil registers for 5,671 children born between 1 August 1914 and 31 December 1916 who were granted the status of "pupille de la Nation" (orphan of the Nation). We used a database comprising 1.4 million deceased soldiers to identify war orphans and collect information on their fathers and then paired each orphan with a nonorphan from the same birth register matched for date of birth, sex, and mother's age at the infant's birth. Mortality between ages 31 and 99 y was analyzed for 2,365 orphan/nonorphan pairs. The mean loss of adult lifespan of orphans who had lost their father before birth was 2.4 y (95% CI: 0.7, 3.9 y) and was the result of increased mortality before age 65 y. Adult lifespan was not reduced when the father's death occurred after the infant's birth. These results support the notion that intrauterine exposure to a major psychological maternal stress can affect human longevity.

Role of DNA methylation at the placental RTL1 gene locus in type 1 diabetes.

Genome-wide association studies (GWAS) have identified more than 40 T1D loci associated with type 1 diabetes (T1D). How these polymorphisms interact with environmental factors to trigger T1D is unknown, but recent evidence suggests that epigenetic mechanisms could play a role. To begin to explore the contribution of epigenetics to T1D, we have examined DNA methylation in a pilot study of whole blood cells DNA from 10 young T1D patients and 10 young controls. Through the study of >900 000 CG loci across a diverse set of functionally relevant genomic regions using a custom DNA methylation array, we identified 250 T1D-differentially methylated region (DMR) at p < 0.05 and 1 DMR using next a permutation-based multiple testing correction method. This DMR is located in an imprinted region previously associated with T1D on the chromosome 14 that encompasses RTL1 gene and 2 miRNAs (miR136 and miR432). Using pyrosequencing-based bisulfite PCR, we replicated this association in a different and larger set of T1D patients and controls. DNA methylation at this DMR was inversely correlated with RTL1 gene expression and positively correlated with miR136 expression in human placentas. The DMR identified in this study presents suggestive evidence for altered methylation site in T1D and provide a promising new candidate gene. RTL1 is essential for placental permeability function in the mid-to-late fetal stages. We suggest that hypo-methylation could increase the fetal exposure to environmental factors in T1D susceptibility.

Higher methylation of the IGF1 P2 promoter is associated with idiopathic short stature.

BACKGROUND: Idiopathic short stature (ISS) has a strong familial component, but genetics explains only part of it. Indeed, environmental factors act on human growth either directly or through epigenetic factors that remain to be determined. Given the importance of the GH/IGF1 axis for child growth, we suspected that such epigenetic factors could involve the CG methylation at the IGF1 gene P2 promoter, which was recently shown to be a transcriptional regulator for IGF1 gene and a major contributor to GH sensitivity. OBJECTIVE: Explore whether the methylation of the two IGF1 low-CG-rich promoters (P1 and P2) is associated with ISS. SUBJECTS AND METHODS: A total of 94 children with ISS were compared with 119 age-matched children of normal height for the methylation of CGs located within the IGF1 promoters measured with bisulphite PCR pyrosequencing. RESULTS: The methylation of 5 CGs of the P2 promoter was higher in ISS children, notably CG-137 (49 ± 4% in ISS vs 46 ± 4 % in control children, P = 9 × 10-5 ). This was also true for CG-611 of the P1 promoter (93 ± 3% vs 91 ± 3% P = 10-4 ). The CG methylation of the IGF1 promoters thus takes place among the multifactorial factors that are associated with ISS.

Variation in FTO contributes to childhood obesity and severe adult obesity.

We identified a set of SNPs in the first intron of the FTO (fat mass and obesity associated) gene on chromosome 16q12.2 that is consistently strongly associated with early-onset and severe obesity in both adults and children of European ancestry with an experiment-wise P value of 1.67 x 10(-26) in 2,900 affected individuals and 5,100 controls. The at-risk haplotype yields a proportion of attributable risk of 22% for common obesity. We conclude that FTO contributes to human obesity and hence may be a target for subsequent functional analyses.

Global epidemiology of type 1 diabetes in young adults and adults: a systematic review.

BACKGROUND: Although type 1 diabetes (T1D) can affect patients of all ages, most epidemiological studies of T1D focus on disease forms with clinical diagnosis during childhood and adolescence. Clinically, adult T1D is difficult to discriminate from certain forms of Type 2 Diabetes (T2D) and from Latent Autoimmune Diabetes in Adults (LADA). METHODS: A systematic review of the literature was performed to retrieve original papers in English, French and Spanish published up to November 6, 2014, reporting the incidence of T1D among individuals aged over 15 years. The study was carried out according to the PRISMA recommendations. RESULTS: We retrieved information reporting incidence of T1D among individuals aged more than 15 years in 35 countries, and published in 70 articles between 1982 and 2014. Specific anti-beta-cell proteins or C-peptide detection were performed in 14 of 70 articles (20%). The most frequent diagnostic criteria used were clinical symptoms and immediate insulin therapy. Country-to-country variations of incidence in those aged >15 years paralleled those of children in all age groups. T1D incidence was larger in males than in females in 44 of the 54 (81%) studies reporting incidence by sex in people >15 years of age. The overall mean male-to-female ratio in the review was 1.47 (95% CI = 1.33-1.60, SD = 0.49, n = 54, p = <0.0001). Overall, T1D incidence decreased in adulthood, after the age of 14 years. CONCLUSIONS: Few studies on epidemiology of T1D in adults are available worldwide, as compared to those reporting on children with T1D. The geographical variations of T1D incidence in adults parallel those reported in children. As opposed to what is known in children, the incidence is generally larger in males than in females. There is an unmet need to evaluate the incidence of autoimmune T1D in adults, using specific autoantibody detection, and to better analyze epidemiological specificities - if any - of adult T1D. PROSPERO REGISTRATION NUMBER: CRD42012002369.

Mutations in GLIS3 are responsible for a rare syndrome with neonatal diabetes mellitus and congenital hypothyroidism.

We recently described a new neonatal diabetes syndrome associated with congenital hypothyroidism, congenital glaucoma, hepatic fibrosis and polycystic kidneys. Here, we show that this syndrome results from mutations in GLIS3, encoding GLI similar 3, a recently identified transcription factor. In the original family, we identified a frameshift mutation predicted to result in a truncated protein. In two other families with an incomplete syndrome, we found that affected individuals harbor deletions affecting the 11 or 12 5'-most exons of the gene. The absence of a major transcript in the pancreas and thyroid (deletions from both families) and an eye-specific transcript (deletion from one family), together with residual expression of some GLIS3 transcripts, seems to explain the incomplete clinical manifestations in these individuals. GLIS3 is expressed in the pancreas from early developmental stages, with greater expression in beta cells than in other pancreatic tissues. These results demonstrate a major role for GLIS3 in the development of pancreatic beta cells and the thyroid, eye, liver and kidney.

Recurrent PRKAR1A mutation in acrodysostosis with hormone resistance.

The skeletal dysplasia characteristic of acrodysostosis resembles the Albright's hereditary osteodystrophy seen in patients with pseudohypoparathyroidism type 1a, but defects in the α-stimulatory subunit of the G-protein (GNAS), the cause of pseudohypoparathyroidism type 1a, are not present in patients with acrodysostosis. We report a germ-line mutation in the gene encoding PRKAR1A, the cyclic AMP (cAMP)-dependent regulatory subunit of protein kinase A, in three unrelated patients with acrodysostosis and resistance to multiple hormones. The mutated subunit impairs the protein kinase A response to stimulation by cAMP; this explains our patients' hormone resistance and the similarities of their skeletal abnormalities with those observed in patients with pseudohypoparathyroidism type 1a.

ß cells keep bad epigenetic memories of palmitate.

Palmitic acid, or hexadecanoic acid, a 16-carbon saturated fatty acid (FA), accounts for approximately 38% of the total circulating FA in lean or obese humans. In an article published in BMC Medicine, Hall et al. report that cultured islets from healthy donors, when exposed to palmitate, undergo changes in CpG methylation that are associated with modifications of expression in 290 genes. Their results provide a first look at the mechanisms used by the endocrine pancreas of humans to keep a durable genomic imprint from their exposure to FA that can influence gene expression and possibly cell phenotype in the long term. It is likely that such studies will help understand the epigenetic response of ß cells to a disturbed metabolic environment, especially one created by obesity.

Comparison of a French pediatric type 1 diabetes cohort's responders and non-responders to an environmental questionnaire.

BACKGROUND: Type 1 diabetes (T1D) incidence has doubled since the 1980's for children aged <5 years old, potentially relevant environmental factors having thus to be sought early in the patient's life. The identification of environmental factors that can explain the changing epidemiology of T1D requires comprehensive environmental inquiries. However, a limitation is the willingness of patients and families to complete these environmental questionnaires. Our objective was to identify patients' personal and social characteristics predictive of the return, time to the return and completeness of a comprehensive environmental questionnaire. METHODS: The parents of 2832 T1D patients aged <15 years old enrolled in the French Isis cohort were sent a 1379-item environmental questionnaire. A geographic information system was used to collect information on patients' socioeconomic environment. Multivariate statistical analyses were conducted to identify predictors of questionnaire return, time to its return and its completeness. RESULTS: Within 6 months, 867 (30.6%) questionnaires were returned. Socioeconomic environment was strongly associated with the probability of response, with fewer responses from cities with high Townsend deprivation index (p =2 × 10-7), high unemployment (p =0.005), blue-collar workers' rate (p =0.0002) and household overcrowding (p =0.02). Response rates were similar for male and female patients, but were higher for less severely affected patients (p =0.006) and younger patients (p =5 × 10-5). When returned, completeness was high with a mean of 96%. CONCLUSION: Identification of personal or socioeconomic characteristics differing between questionnaire responders and non-responders may help target future environmental investigations on those patients who will more likely return the information, and reduce bias using these variables to stratify the analyses.

Increased CpG methylation at the CDH1 locus in inflamed ileal mucosa of patients with Crohn disease.

BACKGROUND: E-cadherin, a major actor of cell adhesion in the intestinal barrier, is encoded by the CDH1 gene associated with susceptibility to Crohn Disease (CD) and colorectal cancer. Since epigenetic mechanisms are suspected to contribute to the multifactorial pathogenesis of CD, we studied CpG methylation at the CDH1 locus. The methylation of the CpG island (CGI) and of the 1st enhancer, two critical regulatory positions, was quantified in surgical specimens of inflamed ileal mucosa and in peripheral blood mononuclear cells (PBMC) of 21 CD patients. Sixteen patients operated on for a non-inflammatory bowel disease, although not normal controls, provided a macroscopically normal ileal mucosa and PBMC for comparison. RESULTS: In ileal mucosa, 19/21 (90%) CD patients vs 8/16 control patients (50%) (p < 0.01) had a methylated CDH1 promoter CGI. In PBMC, CD patients with methylated CGI were 11/21 (52%) vs 7/16 controls (44%), respectively. Methylation in the 1st enhancer of CDH1 was also higher in the CD group for each of the studied CpGs and for their average value (45 ± 17% in CD patients vs 36 ± 17% in controls; p < 0.001). Again, methylation was comparable in PBMC. Methylation of CGI and 1st enhancer were not correlated in mucosa or PBMC. CONCLUSIONS: Methylation of several CpGs at the CDH1 locus was increased in the inflamed ileal mucosa, not in the PBMC, of CD patients, suggesting the association of CDH1 methylation with ileal inflammation. Longitudinal studies will explore if this increased methylation is a risk marker for colorectal cancer.

A common polymorphism of the growth hormone receptor is associated with increased responsiveness to growth hormone.

Growth hormone is used to increase height in short children who are not deficient in growth hormone, but its efficacy varies largely across individuals. The genetic factors responsible for this variation are entirely unknown. In two cohorts of short children treated with growth hormone, we found that an isoform of the growth hormone receptor gene that lacks exon 3 (d3-GHR) was associated with 1.7 to 2 times more growth acceleration induced by growth hormone than the full-length isoform (P < 0.0001). In transfection experiments, the transduction of growth hormone signaling through d3-GHR homo- or heterodimers was approximately 30% higher than through full-length GHR homodimers (P < 0.0001). One-half of Europeans are hetero- or homozygous with respect to the allele encoding the d3-GHR isoform, which is dominant over the full-length isoform. These observations suggest that the polymorphism in exon 3 of GHR is important in growth hormone pharmacogenetics.

Growth hormone receptor polymorphism and growth hormone therapy response in children: a Bayesian meta-analysis.

Recombinant human growth hormone (rhGH) therapy is used in the long-term treatment of children with growth disorders, but there is considerable treatment response variability. The exon 3-deleted growth hormone receptor polymorphism (GHR(d3)) may account for some of this variability. The authors performed a systematic review (to April 2011), including investigator-only data, to quantify the effects of the GHR(fl-d3) and GHR(d3-d3) genotypes on rhGH therapy response and used a recently established Bayesian inheritance model-free approach to meta-analyze the data. The primary outcome was the 1-year change-in-height standard-deviation score for the 2 genotypes. Eighteen data sets from 12 studies (1,527 children) were included. After several prior assumptions were tested, the most appropriate inheritance model was codominant (posterior probability = 0.93). Compared with noncarriers, carriers had median differences in 1-year change-in-height standard-deviation score of 0.09 (95% credible interval (CrI): 0.01, 0.17) for GHR(fl-d3) and of 0.14 (95% CrI: 0.02, 0.26) for GHR(d3-d3). However, the between-study standard deviation of 0.18 (95% CrI: 0.10, 0.33) was considerable. The authors tested by meta-regression for potential modifiers and found no substantial influence. They conclude that 1) the GHR(d3) polymorphism inheritance is codominant, contrasting with previous reports; 2) GHR(d3) genotypes account for modest increases in rhGH effects in children; and 3) considerable unexplained variability in responsiveness remains.

A pilot study of discontinuous, insulin-like growth factor 1-dosing growth hormone treatment in young children with FGFR3 N540K-mutated hypochondroplasia.

OBJECTIVE: To assess the growth promoting effect of a recombinant growth hormone (rGH) treatment protocol adjusted on insulin-like growth factor 1 (IGF-1) dosing in children affected by the most severe forms of FGFR3 N540K-mutated hypochondroplasia. STUDY DESIGN: Midterm results of an open-label, single-center, nonrandomized, 2003-2020 pilot trial to final stature, including 6 children (mean age, 2.6 ± 0.7 years; mean height SDS, -3.0 ± 0.5) with the N540K mutation of FGFR3 gene who received an rGH dosage titrated to an IGF-1 level close to 1.5 SDS of the normal range. rGH therapy was interrupted 1 day per week, 1 month per year, and 6 months every 2 years. RESULTS: The mean height SDS increased by 1.9 during the 6.1 ± 0.9-year study period, reaching -0.8 to -1.3 at age 8.7 ± 1 years. The mean±SDS baseline IGF-1 value was -1.6 ± 0.5 before rGH treatment and 1.4±0.3 during the last year of observation. The average cumulative rGH dose was 0.075 ± 0.018 mg/kg/day (range, 0.059-0.100 mg/kg/day). Trunk/leg disproportion was improved. CONCLUSION: IGF-1-dosing rGH treatment durably improves growth and reduces body disproportion in children with severe forms of hypochondroplasia.

Differentially methylated CpGs in response to growth hormone administration in children with idiopathic short stature.

BACKGROUND: Recombinant human growth hormone (rhGH) has shown a great growth-promoting potential in children with idiopathic short stature (ISS). However, the response to rhGH differs across individuals, largely due to genetic and epigenetic heterogeneity. Since epigenetic marks on the methylome can be dynamically influenced by GH, we performed a comprehensive pharmacoepigenomics analysis of DNA methylation changes associated with long-term rhGH administration in children with ISS. RESULTS: We measured DNA methylation profiles before and after GH treatment (with a duration of ~ 18 months in average) on 47 healthy children using customized methylC-seq capture sequencing. Their changes were compared and associated with changes in plasma IGF1 by adjusting sex, age, treatment duration and estimated blood proportions. We observed a considerable inter-individual heterogeneity of DNA methylation changes responding to GH treatment. We identified 267 response-associated differentially methylated cytosines (DMCs) that were enriched in promoter regions, CpG islands and blood cell-type-specific regulatory elements. Furthermore, the genes associated with these DMCs were enriched in the biology process of "cell development," "neuron differentiation" and "developmental growth," and in the TGF-beta signaling pathway, PPAR Alpha pathway, endoderm differentiation pathway, adipocytokine signaling pathway as well as PI3K-Akt signaling pathway, and cAMP signaling pathway. CONCLUSION: Our study provides a first insight in DNA methylation changes associated with rhGH administration, which may help understand mechanisms of epigenetic regulation on GH-responsive genes.

Long-Term Disease Prevention with a Gene Therapy Targeting Oligodendrocytes in a Mouse Model of Adrenomyeloneuropathy.

Adrenomyeloneuropathy (AMN) is a late-onset axonopathy of spinal cord tracts caused by mutations of the ABCD1 gene that encodes adrenoleukodystrophy protein (ALDP), a peroxisomal transporter of very long-chain fatty acids (VLCFA). Disturbed metabolic interaction between oligodendrocytes (OL) and axons is suspected to play a major role in AMN axonopathy. To develop a vector targeting OL, the human ABCD1 gene driven by a short 0.3 kb part of the human myelin-associated glycoprotein (MAG) promoter was packaged into an adeno-associated viral serotype 9 (rAAV9). An intravenous injection of this vector on postnatal day 10 in Abcd1-/- mice, a model of AMN, allowed a near normal motor performance to persist for 24 months, while age-matched untreated mice developed major defects of balance and motricity. Three weeks postvector, 50-54% of spinal cord white matter OL was expressing human ALDP (hALDP) at the cervical level, and only 6-7% after 24 months. In addition, 29-32% of cervical spinal cord astrocytes at 3 weeks and 16-19% at 24 months also expressed ALDP. C26:0-lysoPC, a sensitive VLCFA marker of AMN, was lower by 41% and 50%, respectively, in the spinal cord and brain of vector-treated compared with untreated mice. In a nonhuman primate, the intrathecal injection of the rAAV9-MAG vector induced abundant ALDP expression at 3 weeks in spinal cord OL (43%, 29%, and 26% at cervical, thoracic, and lumbar levels) and cerebellum OL (35%). In addition, 33-41% of spinal cord astrocytes expressed hALDP, and 27% of cerebellar astrocytes. To our knowledge, OL targeting had not been obtained before in primates with other vectors or promoters. The current results thus provide a robust proof-of-concept not only for the gene therapy of AMN but also for other central nervous system diseases, where the targeting of OL with the rAAV9-MAG vector may be of interest.

Adeno-associated virus gene therapy with cholesterol 24-hydroxylase reduces the amyloid pathology before or after the onset of amyloid plaques in mouse models of Alzheimer's disease.

The development of Alzheimer's disease (AD) is closely connected with cholesterol metabolism. Cholesterol increases the production and deposition of amyloid-beta (Abeta) peptides that result in the formation of amyloid plaques, a hallmark of the pathology. In the brain, cholesterol is synthesized in situ but cannot be degraded nor cross the blood-brain barrier. The major exportable form of brain cholesterol is 24S-hydroxycholesterol, an oxysterol generated by the neuronal cholesterol 24-hydroxylase encoded by the CYP46A1 gene. We report that the injection of adeno-associated vector (AAV) encoding CYP46A1 in the cortex and hippocampus of APP23 mice before the onset of amyloid deposits markedly reduces Abeta peptides, amyloid deposits and trimeric oligomers at 12 months of age. The Morris water maze (MWM) procedure also demonstrated improvement of spatial memory at 6 months, before the onset of amyloid deposits. AAV5-wtCYP46A1 vector injection in the cortex and hippocampus of amyloid precursor protein/presenilin 1 (APP/PS) mice after the onset of amyloid deposits also reduced markedly the number of amyloid plaques in the hippocampus, and to a less extent in the cortex, 3 months after the injection. Our data demonstrate that neuronal overexpression of CYP46A1 before or after the onset of amyloid plaques significantly reduces Abeta pathology in mouse models of AD.

Long-Term Follow-Up of Hematopoietic Stem-Cell Gene Therapy for Cerebral Adrenoleukodystrophy.

In 2009, cerebral adrenoleukodystrophy (c-ALD) became the first brain disease to be treated with lentiviral (LV)-based hematopoietic stem cell gene therapy with the ABCD1 gene in four boys (P1-P4) who had demyelinating lesions expected to be lethal in the short term and no bone marrow donor. We report the clinical and magnetic resonance imaging (MRI) follow-up over a mean of 8.8 years posttransplant. In parallel, vector genome copies, expression of transgenic ALD protein (ALDP), and viral integration sites were determined in peripheral blood cells. Prior to transplant, the four patients had a normal or near normal neurocognitive status but gadolinium-enhanced demyelination in various brain regions. Gadolinium diffusion disappeared during the first year posttransplant. P3 kept a near normal status until 8.3 years of follow-up, but P1, P2, and P4 showed major cognitive degradation around 9, 28, and 60 months posttransplant. Neurological status and demyelination stabilized until last evaluation in P2, but deteriorated in both P1 at 10 years and P4 at 3 years posttransplant. The proportion of myeloid and lymphoid cells expressing transgenic ALDP decreased by half within 5 years then stabilized around 5% to 10%. Integration site analysis revealed a durable polyclonal distribution of genetically corrected hematopoietic cells. No adverse effects were observed. The long-term arrest of demyelination at MRI and persistence of transduced hematopoietic progenitors support that LV gene therapy may be a safe and durable treatment of c-ALD. However, the neurological degradation observed in three out of four patients mitigates the benefit of this therapy, calling for an earlier intervention, more potent vectors, and additional therapeutic strategies.