Cholesterol 24-hydroxylase defect is implicated in memory impairments associated with Alzheimer-like Tau pathology

Alzheimer's disease (AD) is characterized by both amyloid and Tau pathologies. The amyloid component and altered cholesterol metabolism are closely linked, but the relationship between Tau pathology and cholesterol is currently unclear. Brain cholesterol is synthesized in situ and cannot cross the blood-brain barrier: to be exported from the central nervous system into the blood circuit, excess cholesterol must be converted to 24S-hydroxycholesterol by the cholesterol 24-hydroxylase encoded by the CYP46A1 gene. In AD patients, the concentration of 24S-hydroxycholesterol in the plasma and the cerebrospinal fluid are lower than in healthy controls. The THY-Tau22 mouse is a model of AD-like Tau pathology without amyloid pathology. We used this model to investigate the potential association between Tau pathology and CYP46A1 modulation. The amounts of CYP46A1 and 24S-hydroxycholesterol in the hippocampus were lower in THY-Tau22 than control mice. We used an adeno-associated virus (AAV) gene transfer strategy to increase CYP46A1 expression in order to investigate the consequences on THY-Tau22 mouse phenotype. Injection of the AAV-CYP46A1 vector into the hippocampus of THY-Tau22 mice led to CYP46A1 and 24S-hydroxycholesterol content normalization. The cognitive deficits, impaired long-term depression and spine defects that characterize the THY-Tau22 model were completely rescued, whereas Tau hyperphosphorylation and associated gliosis were unaffected. These results argue for a causal link between CYP46A1 protein content and memory impairments that result from Tau pathology. Therefore, CYP46A1 may be a relevant therapeutic target for Tauopathies and especially for AD.

Thyroid hormone receptor beta1 is expressed in the human hair follicle

To understand better the mechanisms by which thyroid hormone can exert its effects on the hair follicle, we looked for the expression of members of the thyroid hormone receptor (TR) family in human hair follicles. Immunoreactive TRs were detected in both dermal and epithelial compartments of the human pilosebaceous unit. Using reverse transcriptase-polymerase chain reaction, we established that TRbeta1 was the predominant form of TR expressed in the human hair follicle. In addition, we investigated the effects of 3,3', 5-triiodo-L-thyronine (T3) on the survival of human hair follicles in vitro, to understand the role of this thyroid hormone on hair follicle homeostasis. A physiological level of free T3 significantly enhanced human hair survival in vitro.

Intracerebral Gene Therapy Using AAVrh.10-hARSA Recombinant Vector to Treat Patients with Early-Onset Forms of Metachromatic Leukodystrophy: Preclinical Feasibility and Safety Assessments in Nonhuman Primates

No treatment is available for early-onset forms of metachromatic leukodystrophy (MLD), a lysosomal storage disease caused by autosomal recessive defect in arylsulfatase A (ARSA) gene causing severe demyelination in central and peripheral nervous systems. We have developed a gene therapy approach, based on intracerebral administration of AAVrh.10-hARSA vector, coding for human ARSA enzyme. We have previously demonstrated potency of this approach in MLD mice lacking ARSA expression. We describe herein the preclinical efficacy, safety, and biodistribution profile of intracerebral administration of AAVrh.10-hARSA to nonhuman primates (NHPs). NHPs received either the dose planned for patients adjusted to the brain volume ratio between child and NHP (1×dose, 1.1×10(11) vg/hemisphere, unilateral or bilateral injection) or 5-fold this dose (5×dose, 5.5×10(11) vg/hemisphere, bilateral injection). NHPs were subjected to clinical, biological, and brain imaging observations and were euthanized 7 or 90 days after injection. There was no toxicity based on clinical and biological parameters, nor treatment-related histological findings in peripheral organs. A neuroinflammatory process correlating with brain MRI T2 hypersignals was observed in the brain 90 days after administration of the 5×dose, but was absent or minimal after administration of the 1×dose. Antibody response to AAVrh.10 and hARSA was detected, without correlation with brain lesions. After injection of the 1×dose, AAVrh.10-hARSA vector was detected in a large part of the injected hemisphere, while ARSA activity exceeded the normal endogenous activity level by 14-31%. Consistently with other reports, vector genome was detected in off-target organs such as liver, spleen, lymph nodes, or blood, but not in gonads. Importantly, AAVrh.10-hARSA vector was no longer detectable in urine at day 7. Our data demonstrate requisite safe and effective profile for intracerebral AAVrh.10-hARSA delivery in NHPs, supporting its clinical use in children affected with MLD.

In vivo real-time dynamics of ATP and ROS production in axonal mitochondria show decoupling in mouse models of peripheral neuropathies

Mitochondria are critical for the function and maintenance of myelinated axons notably through Adenosine triphosphate (ATP) production. A direct by-product of this ATP production is reactive oxygen species (ROS), which are highly deleterious for neurons. While ATP shortage and ROS levels increase are involved in several neurodegenerative diseases, it is still unclear whether the real-time dynamics of both ATP and ROS production in axonal mitochondria are altered by axonal or demyelinating neuropathies. To answer this question, we imaged and quantified mitochondrial ATP and hydrogen peroxide (H2O2) in resting or stimulated peripheral nerve myelinated axons in vivo, using genetically-encoded fluorescent probes, two-photon time-lapse and CARS imaging. We found that ATP and H2O2 productions are intrinsically higher in nodes of Ranvier even in resting conditions. Axonal firing increased both ATP and H2O2 productions but with different dynamics: ROS production peaked shortly and transiently after the stimulation while ATP production increased gradually for a longer period of time. In neuropathic MFN2R94Q mice, mimicking Charcot-Marie-Tooth 2A disease, defective mitochondria failed to upregulate ATP production following axonal activity. However, elevated H2O2 production was largely sustained. Finally, inducing demyelination with lysophosphatidylcholine resulted in a reduced level of ATP while H2O2 level soared. Taken together, our results suggest that ATP and ROS productions are decoupled under neuropathic conditions, which may compromise axonal function and integrity.

Expression of peroxisome proliferator activated receptors (PPARs) in human hair follicles and PPAR alpha involvement in hair growth

Peroxisome proliferator-activated receptors (PPARs), which belong to the nuclear hormone receptor superfamily, have recently been described as potent key regulators of epidermal development. As 1,25-dihydroxyvitamin D3, retinoic acid and triiodothyronine are known to exert effects on skin and hair follicle growth through similar receptors, we decided to investigate both the expression pattern of the PPAR alpha, -delta and -gamma subtypes and their role in human hair follicles. Using reverse transcriptase-polymerase chain reaction and immunohistochemistry, we established that PPAR alpha, -delta and -gamma were expressed in both dermal and epithelial human hair follicle cells. Additionally, we evaluated the dose effect of clofibrate, a PPAR alpha ligand, on the survival of human hair follicles in culture. A beneficial effect was observed within a narrow range of concentrations.

Pro-inflammatory cytokine cascade in human plucked hair

Using reverse transcriptase polymerase chain reaction we showed that freshly plucked human anagen hair expressed both type 1 (80 kD) and type 2 (60 kD) interleukin (IL)-1 receptor mRNAs. The IL-1 receptor type 1 was functional since after in vitro stimulation of plucked hair with IL-1 alpha, we observed the induction of mRNA(s) for the inflammatory cytokines IL-1 beta, tumour necrosis factor alpha and IL-6 as well as for the chemokines monocyte chemotactic and activating factor and IL-8. In addition, the growth of dissected human anagen hairs in culture in vitro was significantly and dose-dependently inhibited by IL-1 alpha as a consequence of hair bulb degradation. These observations, together with those of other authors in IL-1 alpha transgenic mice evidence the inhibitory role of IL-1 on human hair growth. Therefore, in order to identify individuals with high inflammatory potential in their hair follicle environment, we designed a rapid and simple assay to detect variations in the level of IL-1 alpha production in the overnight supernatant of plucked hairs in culture. We observed that 32.7% of the specimens from the volunteers tested (n = 116) could be considered highly inflammatory in terms of IL-1 alpha production. Altogether, these results suggest that in alopecia androgenetica, hair growth might be negatively influenced by IL-1, directly produced by the outer root sheath keratinocytes. Consequently, identifying the "inflammatory alopecic individual' might be of clinical interest to discriminate among individuals for whom anti-IL-1 strategies might be of therapeutic relevance.

On-resin cyclization of peptide ligands of the Vascular Endothelial Growth Factor Receptor 1 by copper(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition

Cyclic peptides were obtained, on-resin, by the copper (I) catalysed 1,3-dipolar cycloaddition of azides and alkynes. The reaction led exclusively to the formation of the expected cyclomonomeric products which acted as ligands of the Vascular Endothelial Growth Factor receptor 1.

Targeting the proangiogenic VEGF-VEGFR protein-protein interface with drug-like compounds by in silico and in vitro screening

Protein-protein interactions play a central role in medicine, and their modulation with small organic compounds remains an enormous challenge. Because it has been noted that the macromolecular complexes modulated to date have a relatively pronounced binding cavity at the interface, we decided to perform screening experiments over the vascular endothelial growth factor receptor (VEGFR), a validated target for antiangiogenic treatments with a very flat interface. We focused the study on the VEGFR-1 D2 domain, and 20 active compounds were identified. These small compounds contained a (3-carboxy-2-ureido)thiophen unit and had IC(50) values in the low micromolar range. The most potent compound inhibited the VEGF-induced VEGFR-1 transduction pathways. Our findings suggest that our best hit may be a promising scaffold to probe this macromolecular complex and for the development of treatments of VEGFR-1-dependent diseases.

Biochemical and structural analysis of the binding determinants of a vascular endothelial growth factor receptor peptidic antagonist

Cyclic peptide antagonist c[YYDEGLEE]-NH(2), which disrupts the interaction between vascular endothelial growth factor (VEGF) and its receptors (VEGFRs), represents a promising tool in the fight against cancer and age-related macular degeneration. Furthermore, coupled to a cyclen derivative, this ligand could be used as a medicinal imaging agent. Nevertheless, before generating such molecular probes, some preliminary studies need to be undertaken in order to define the more suitable positions for introduction of the cyclen macrocycle. Through an Ala-scan study on this peptide, we identified its binding motif, and an NMR study highlights its binding sites on the VEGFR-1D2 Ig-like domain. Guided by the structural relationship results deduced from the effect of the peptides on endothelial cells, new peptides were synthesized and grafted on beads. Used in a pull-down assay, these new peptides trap the VEGFRs, thus confirming that the identified amino acid positions are suitable for further derivatization.

Rational Design, Structure, and Biological Evaluation of Cyclic Peptides Mimicking the Vascular Endothelial Growth Factor

Angiogenesis is the development of a novel vascular network from a pre-existing structure. Blocking angiogenesis is an attractive strategy to inhibit tumor growth and metastasis formation. Based on structural and mutagenesis data, we have developed novel cyclic peptides that mimic, simultaneously, two regions of the VEGF crucial for the interaction with the VEGF receptors. The peptides, displaying the best affinity for VEGF receptor 1 on a competition assay, inhibited endothelial cell transduction pathway, migration, and capillary-like tubes formation. The specificity of these peptides for VEGF receptors was demonstrated by microscopy using a fluorescent peptide derivative. The resolution of the structure of some cyclic peptides by NMR and molecular modeling has allowed the identification of various factors accounting for their inhibitory activity. Taken together, these results validate the selection of these two regions as targets to develop molecules able to disturb the development of cancer and angiogenesis-associated diseases.

Hair keratin pattern in human hair follicles grown in vitro

The keratin family includes epithelial (soft) keratins and hair (hard) keratins, and can be divided into acidic type I and basic to neutral type II subfamilies. Recently, nine type I and six type II hair keratin genes have been characterized through the screening of a human PAC library. The expression of these genes in the hair follicle was determined in vivo and a combined catalog of acidic and basic hair keratins was established. In this study, we investigated the expression and localization of most of the human hair keratin members of both types in human hair grown in vitro. We show that in vitro growth of hair follicles for 10 days in complete William's E culture medium did not alter the expression pattern of hair keratins. Similarly to the in vivo situation, each hair keratin was localized in precise and discrete compartments of the follicle, ranging from the matrix to the upper cortex and/or the hair cuticle. This study shows that the increase in length of in vitro grown follicles was accompanied by the proper hair shaft keratinization process. It also shows that hair follicle integrity was maintained in vitro, both in terms of gross morphology and molecular organization despite the complexity of the keratin expression pattern.

Are semen parameters related to birth weight?

Several experimental models suggest a link between maternal nutrition during gestation and reproductive function in offspring, but the impact of birth weight on male fertility in adulthood in humans is poorly documented. To study whether birth weight is associated with unexplained male subfertility later in life, we evaluated the relationship between birth weight and sperm parameters in adulthood in white subfertile men, partners of couples with primary idiopathic subfertility, and fertile men recruited within the ALIFERT (Diet and Its Relationship with Couple Infertility) study. Total sperm count, progressive motility, and sperm DNA fragmentation were analyzed in sperm, and metabolic assays were performed on blood. Birth weight was associated with sperm DNA fragmentation and inversely correlated with total sperm count, underlining the importance of the in utero environment for male reproductive function.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01093378.

Metabolic syndrome and smoking are independent risk factors of male idiopathic infertility

Background

Overweight and obesity are known to impact male fertility and are commonly associated with abdominal obesity and metabolic disorders. The association between abdominal obesity or metabolic syndrome with male reproduction has not been fully investigated. Moreover, many factors may interfere with the evaluation of the impact of metabolic syndrome on male fertility. Thus, tobacco is known to alter the spermatic parameters and phenomena linking smoking with metabolic syndrome are therefore complex. The main objective of this study has been to investigate the potential association of metabolic syndrome with male idiopathic infertility given smoking status.

Materiel and methods

The data of this study concerned infertile (n = 96) and fertile (n = 100) men under 45 years of age who have been recruited in the ALIFERT case-control study. Body mass index and waist circumference were measured. Serum triglycerides, cholesterol (total, high density lipoprotein, and low density lipoprotein cholesterol) and fasting blood glucose were assayed. Metabolic syndrome has been diagnosed in the presence of at least three of the following criteria: increased waist circumference, high triglycerides, fasting glucose or arterial blood pressure and low high density lipoprotein cholesterol.

Results

The present study reports that infertile men are in poorer health condition compared to fertile men and are more often smokers. The results of this study suggested metabolic syndrome and smoking to be independent risk factor for idiopathic infertility.

Conclusions

Metabolic syndrome and smoking should systematically be checked at the beginning of medical care in infertile males and personal and multifaceted coaching should be proposed to deal jointly with smoking and metabolic disorders.

Trial registration

NCT01093378 ALIFERT. Registered: March 25, 2010.

Targeting VEGFR1 on endothelial progenitors modulates their differentiation potential

OBJECTIVES

We studied whether plasma levels of angiogenic factors VEGF and placental growth factor (PlGF) in coronary artery disease patients or undergoing cardiac surgery are modified, and whether those factors modulate endothelial progenitor's angiogenic potential.

METHODS AND RESULTS

A total of 143 patients' plasmas from two different studies were analyzed (30 coronary artery disease patients, 30 patients with stable angina, coupled with 30 age and sex-matched controls; 53 patients underwent cardiac surgery). Among factors screened, only PlGF was found significantly increased in these pathological populations. PlGF-1 and PlGF-2 were then tested on human endothelial-colony-forming cells (ECFCs). We found that PlGF-1 and PlGF-2 induce VEGFR1 phosphorylation and potentiate ECFCs tubulogenesis in vitro. ECFCs VEGFR1 was further inhibited using a specific small interfering RNA (siRNA) and the chemical compound 4321. We then observed that the VEGFR1-siRNA and the compound 4321 decrease ECFCs tubulogenesis potential in vitro. Finally, we tested the compound 4321 in the preclinical Matrigel(®)-plug model with C57Bl/6J mice as well as in the murine hindlimb ischemia model. We found that 4321 inhibited the plug vascularization, attested by the hemoglobin content and the VE-Cadherin expression level and that 4321 inhibited the post-ischemic revascularization.

CONCLUSION

PlGF plasma levels were found increased in cardiovascular patients. Disrupting PlGF/VEGFR1 pathway could modulate ECFC-induced tubulogenesis, the cell type responsible for newly formed vessels in vivo.

Biophysical Studies of the Induced Dimerization of Human VEGF Receptor 1 Binding Domain by Divalent Metals Competing with VEGF-A

Angiogenesis is tightly regulated through the binding of vascular endothelial growth factors (VEGFs) to their receptors (VEGFRs). In this context, we showed that human VEGFR1 domain 2 crystallizes in the presence of Zn²⁺, Co²⁺ or Cu²⁺ as a dimer that forms via metal-ion interactions and interlocked hydrophobic surfaces. SAXS, NMR and size exclusion chromatography analyses confirm the formation of this dimer in solution in the presence of Co²⁺, Cd²⁺ or Cu²⁺. Since the metal-induced dimerization masks the VEGFs binding surface, we investigated the ability of metal ions to displace the VEGF-A binding to hVEGFR1: using a competition assay, we evidenced that the metals displaced the VEGF-A binding to hVEGFR1 extracellular domain binding at micromolar level.