Huntington disease (HD) is a genetic neurodegenerative disorder for which there is currently no cure and no way to stop or even slow the brain changes it causes. In the present study, we aimed to investigate whether FTY720, the first approved oral therapy for multiple sclerosis, may be effective in HD models and eventually constitute an alternative therapeutic approach for the treatment of the disease. Here, we utilized preclinical target validation paradigms and examined the in vivo efficacy of chronic administration of FTY720 in R6/2 HD mouse model. Our findings indicate that FTY720 improved motor function, prolonged survival and reduced brain atrophy in R6/2 mice. The beneficial effect of FTY720 administration was associated with a significant strengthening of neuronal activity and connectivity and, with reduction of mutant huntingtin aggregates, and it was also paralleled by increased phosphorylation of mutant huntingtin at serine 13/16 residues that are predicted to attenuate protein toxicity.

Rationale:: Long living individuals show delay of aging, which is characterized by the progressive loss of cardiovascular homeostasis, along with reduced endothelial nitric oxide synthase activity, endothelial dysfunction, and impairment of tissue repair after ischemic injury. Objective:: Exploit genetic analysis of long living individuals to reveal master molecular regulators of physiological aging and new targets for treatment of cardiovascular disease. Methods and Results:: We show that the polymorphic variant rs2070325 (Ile229Val) in bactericidal/permeability-increasing fold-containing-family-B-member-4 (BPIFB4) associates with exceptional longevity, under a recessive genetic model, in 3 independent populations. Moreover, the expression of BPIFB4 is instrumental to maintenance of cellular and vascular homeostasis through regulation of protein synthesis. BPIFB4 phosphorylation/activation by protein-kinase-R–like endoplasmic reticulum kinase induces its complexing with 14-3-3 and heat shock protein 90, which is facilitated by the longevity-associated variant. In isolated vessels, BPIFB4 is upregulated by mechanical stress, and its knock-down inhibits endothelium-dependent vasorelaxation. In hypertensive rats and old mice, gene transfer of longevity-associated variant-BPIFB4 restores endothelial nitric oxide synthase signaling, rescues endothelial dysfunction, and reduces blood pressure levels. Furthermore, BPIFB4 is implicated in vascular repair. BPIFB4 is abundantly expressed in circulating CD34 ⁺ cells of long living individuals, and its knock-down in endothelial progenitor cells precludes their capacity to migrate toward the chemoattractant SDF-1. In a murine model of peripheral ischemia, systemic gene therapy with longevity-associated variant-BPIFB4 promotes the recruitment of hematopoietic stem cells, reparative vascularization, and reperfusion of the ischemic muscle. Conclusions:: Longevity-associated variant-BPIFB4 may represent a novel therapeutic tool to fight endothelial dysfunction and promote vascular reparative processes.

Summary: Purpose: The chemokine fractalkine/CX3CL1 and its receptor CX3CR1 are widely expressed in the central nervous system (CNS). Recent evidence showed that CX3CL1 participates in inflammatory responses that are common features of CNS disorders, such as epilepsy. Mesial temporal lobe epilepsy (MTLE) is the prevalent form of focal epilepsy in adults, and hippocampal sclerosis (HS) represents the most common underlying pathologic abnormality, as demonstrated at autopsy and postresection studies. Relevant features of MTLE are a characteristic pattern of neuronal loss, as are astrogliosis and microglia activation. Several factors affect epileptogenesis in patients with MTLE, including a lack of γ‐aminobutyric acid (GABA)ergic inhibitory efficacy. Therefore, experiments were designed to investigate whether, in MTLE brain tissues, CX3CL1 may influence GABA_A receptor (GABA_AR) mediatedtransmission, with a particular focus on the action of CX3CL1 on the use‐dependent decrease (rundown) of the GABA‐evoked currents (I_GABA), a feature underlying the reduction of GABAergic function in epileptic tissue.Methods: Patch‐clamp recordings were obtained from cortical pyramidal neurons in slices from six MTLE patients after surgery. Alternatively, the cell membranes from epileptic brain tissues of 17 MTLE patients or from surgical samples and autopsies of nonepileptic patients were microtransplanted into Xenopus oocytes, and I_GABA were recorded using the standard two‐microelectrode voltage‐clamp technique. Immunohistochemical staining and double‐labeling studies were carried out on the same brain tissues to analyze CX3CR1 expression.Key Findings: In native pyramidal neurons from cortical slices of patients with MTLE, CX3CL1 reduced I_GABA rundown and affected the recovery of I_GABA amplitude from rundown. These same effects were confirmed in oocytes injected with cortical and hippocampal MTLE membranes, whereas CX3CL1 did not influence I_GABA in oocytes injected with nonepileptic tissues. Consistent with a specific effect of CX3CL1 on tissues from patients with MTLE, CX3CR1 immunoreactivity was higher in MTLE sclerotic hippocampi than in control tissues, with a prominent expression in activated microglial cells.Significance: These findings indicate a role for CX3CL1 in MTLE, supporting recent evidence on the relevance of brain inflammation in human epilepsies. Our data demonstrate that in MTLE tissues the reduced GABAergic function can be modulated by CX3CL1. The increased CX3CR1 expression in microglia and the modulation by CX3CL1 of GABAergic currents in human epileptic brain suggests new therapeutic approaches for drug‐resistant epilepsies based on the evidence that the propagation of seizures can be influenced by inflammatory processes.

Slow‐channel congenital myasthenic syndrome, caused by mutations in subunits of the endplate ACh receptor (AChR), results in prolonged synaptic currents and excitotoxic injury of the postsynaptic region by Ca²⁺ overloading. The Ca²⁺ overloading could be due entirely to the prolonged openings of the AChR channel or could be abetted by enhanced Ca²⁺ permeability of the mutant channels. We therefore measured the fractional Ca²⁺ current, defined as the percentage of the total ACh‐evoked current carried by Ca²⁺ ions (P_f), for AChRs harbouring the αG153S or the αV249F slow‐channel mutation, and for wild‐type human AChRs in which P_f has not yet been determined. Experiments were performed in transiently transfected GH4C1 cells and human myotubes with simultaneous recording of ACh‐evoked whole‐cell currents and fura‐2 fluorescence signals. We found that the P_f of the wild‐type human endplate AChR was unexpectedly high (P_f∼7%), but neither the αV249F nor the αG153S mutation altered P_f. Fetal human AChRs containing either the wild‐type or the mutated α subunit had a much lower P_f (2–3%). We conclude that the Ca²⁺ permeability of human endplate AChRs is higher than that reported for any other human nicotinic AChR, with the exception of α7‐containing AChRs (P_f > 10%); and that neither the αG153S nor the αV249F mutations affect the P_f of fetal or adult endplate AChRs. However, the intrinsically high Ca²⁺ permeability of human AChRs probably predisposes to development of the endplate myopathy when opening events of the AChR channel are prolonged by altered AChR‐channel kinetics.