After peripheral nerve injury, neurotrophins play a key role in the regeneration of damaged axons that can be augmented by exercise, although the distinct roles played by neurons and Schwann cells ...are unclear. In this study, we evaluated the requirement for the neurotrophin, brain-derived neurotrophic factor (BDNF), in neurons and Schwann cells for the regeneration of peripheral axons after injury. Common fibular or tibial nerves in thy-1-YFP-H mice were cut bilaterally and repaired using a graft of the same nerve from transgenic mice lacking BDNF in Schwann cells (BDNF(-/-)) or wild-type mice (WT). Two weeks postrepair, axonal regeneration into BDNF(-/-) grafts was markedly less than WT grafts, emphasizing the importance of Schwann cell BDNF. Nerve regeneration was enhanced by treadmill training posttransection, regardless of the BDNF content of the nerve graft. We further tested the hypothesis that training-induced increases in BDNF in neurons allow regenerating axons to overcome a lack of BDNF expression in cells in the pathway through which they regenerate. Nerves in mice lacking BDNF in YFP(+) neurons (SLICK) were cut and repaired with BDNF(-/-) and WT nerves. SLICK axons lacking BDNF did not regenerate into grafts lacking Schwann cell BDNF. Treadmill training could not rescue the regeneration into BDNF(-/-) grafts if the neurons also lacked BDNF. Both Schwann cell- and neuron-derived BDNF are thus important for axon regeneration in cut peripheral nerves.
Fusion of intracellular trafficking vesicles is mediated by the assembly of SNARE proteins into membrane-bridging complexes. SNARE-mediated membrane fusion requires Sec1/Munc18-family (SM) proteins, ...SNARE chaperones that can function as templates to catalyze SNARE complex assembly. Paradoxically, the SM protein Munc18-1 traps the Qa-SNARE protein syntaxin-1 in an autoinhibited closed conformation. Here we present the structure of a second SM-Qa-SNARE complex, Vps45-Tlg2. Strikingly, Vps45 holds Tlg2 in an open conformation, with its SNARE motif disengaged from its Habc domain and its linker region unfolded. The domain 3a helical hairpin of Vps45 is unfurled, exposing the presumptive R-SNARE binding site to allow template complex formation. Although Tlg2 has a pronounced tendency to form homo-tetramers, Vps45 can rescue Tlg2 tetramers into stoichiometric Vps45-Tlg2 complexes. Our findings demonstrate that SM proteins can engage Qa-SNAREs using at least two different modes, one in which the SNARE is closed and one in which it is open.
Deficiency of phenylalanine hydroxylase causes phenylketonuria (PKU) with elevated phenylalanine (Phe) levels and associated neuropsychiatric and neurocognitive symptoms. Pegvaliase (PEGylated ...phenylalanine ammonia lyase) is an investigational agent to lower plasma Phe in adults with PKU. This study aimed to characterize the long-term efficacy, safety, and immunogenicity of pegvaliase in adults with PKU.
PAL-003 is an ongoing, open-label, long-term extension study of the pegvaliase dose-finding parent phase 2 studies. Participants continued the dose of pegvaliase from one of three parent studies, with dose adjustments to achieve a plasma Phe concentration between 60 and 600 μmol/L.
Mean (standard deviation SD) plasma Phe at treatment-naïve baseline for 80 participants in the parent studies was 1302.4 (351.5) μmol/L. In the 68 participants who entered the extension study, plasma Phe decreased 58.9 (39)% from baseline, to 541.6 (515.5) μmol/L at Week 48 of treatment. Plasma Phe concentrations ≤120 μmol/L, ≤360 μmol/L, and ≤ 600 μmol/L were achieved by 78.7, 80.0, and 82.5% of participants, respectively. Mean (SD) protein intake at baseline was 69.4 (40.4) g/day (similar to the recommended intake for the unaffected population) and remained stable throughout the study. All participants experienced adverse events (AEs), which were limited to mild or moderate severity in most (88.8%); the most common AEs were injection-site reaction (72.5%), injection-site erythema (67.5%), headache (67.5%), and arthralgia (65.0%). The AE rate decreased from 58.3 events per person-year in the parent studies to 18.6 events per person-year in the extension study.
Pegvaliase treatment in adults with PKU produced meaningful and persistent reductions in mean plasma Phe concentration with a manageable safety profile for most subjects that continued with long-term treatment.
ClinicalTrials.gov , NCT00924703. Registered June 18, 2009, https://clinicaltrials.gov/ct2/show/NCT00924703.
Abstract Purpose Morquio A syndrome (mucopolysaccharidosis IVA MPS IVA) is a lysosomal storage disorder caused by deficiency of the enzyme N -acetylgalactosamine-6-sulfatase, which is required to ...degrade the glycosaminoglycan keratan sulfate. Morquio A is associated with extensive morbidity and early mortality. Elosulfase alfa is an enzyme replacement therapy that provides a treatment option for patients with Morquio A. We examined the immunogenicity profile of elosulfase alfa, assessing any correlations between antidrug antibodies and the efficacy and safety outcomes in 176 patients with Morquio A from a 24-week international Phase III trial. Methods Patients were randomized to placebo (n = 59) or elosulfase alfa 2.0 mg/kg administered weekly (n = 58) or every other week (n = 59) as an ~4-hour infusion. Blood samples were routinely tested to determine drug-specific total antibody titer and neutralizing antibody (NAb) positivity. Drug-specific immunoglobulin E positivity was tested routinely and in response to severe hypersensitivity adverse events (AEs). Antidrug antibody positivity and titer were compared with efficacy and safety metrics to assess possible correlations. Findings The 176 patients in the trial were 54% female, with a mean age of 11.9 years. In all patients treated with elosulfase alfa antidrug antibodies developed, and in the majority, antibodies capable of interfering with cation-independent mannose-6-phosphate receptor binding in vitro (NAb) developed. Less than 10% of patients tested positive for drug-specific IgE during the study. Despite the high incidence of anti–elosulfase alfa antibodies, no correlations were detected between higher total antibody titers or NAb positivity and worsened 6-minute walk test results, urine keratin sulfate levels, or hypersensitivity AEs. Drug-specific IgE pos i tivity had no apparent association with the occurrence of anaphylaxis, other hypersensitivity AEs, and/or treatment withdrawal. Implications Despite the universal development of antidrug antibodies, elosulfase alfa treatment was both safe and well tolerated and immunogenicity was not associated with reduced treatment effect. ClinicalTrials.gov identifier: NCT01275066. ( Clin Ther.
Adeno-associated virus (AAV)-based gene therapies have recently shown promise as a novel treatment for hereditary diseases. Due to the viral origin of the vector capsid, however, cellular immune ...response may be elicited that could eliminate transduced target cells. To monitor cellular immune responses in clinical trials, we optimized and bioanalytically validated a sensitive, robust, and reliable interferon-γ (IFN-γ) enzyme-linked immunospot (ELISpot) assay. For method performance validation, human peripheral blood mononuclear cells (PBMCs) were stimulated with peptides derived from AAV5 capsid proteins and the encoded transgene product, human blood clotting factor VIII (FVIII), in addition to positive controls, such as peptides from the 65-kDa phosphoprotein of cytomegalovirus. We statistically assessed the limit of detection and confirmatory cutpoint, evaluated precision and linearity, and confirmed specificity using HIV peptides. Robustness parameter ranges and sample stability periods were established. The validated IFN-γ ELISpot assay was then implemented in an AAV5-FVIII gene therapy clinical trial. Cellular immune responses against the AAV5 capsid were observed in most participants as soon as 2 weeks following dose administration; only limited responses against the transgene product were detected. These data underscore the value of using validated methods for monitoring cellular immunity in AAV gene therapy trials.
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This article describes experimental and statistical approaches for the bioanalytical validation of an interferon-γ ELISpot assay to measure cellular immune responses against AAV5 gene therapy. The validated method was subsequently used with clinical trial PBMC samples following AAV5-FVIII administration and detected anti-AAV5 capsid responses in the majority of participants tested.
This study was conducted to identify potential biomarkers that could be used to evaluate disease progression and monitor responses to enzyme replacement therapy (ERT) in patients with ...mucopolysaccharidosis (MPS) IVA.
Levels of 88 candidate biomarkers were compared in plasma samples from 50 healthy controls and 78 MPSIVA patients not receiving ERT to test for significant correlations to the presence of MPSIVA. MPSIVA samples were also tested for correlations between candidate biomarkers and age, endurance, or urinary keratin sulfate (KS) levels. Then, levels of the same 88 analytes were followed over 36 weeks in 20 MPSIVA patients receiving ERT to test for significant correlations related to ERT, age, or endurance.
Nineteen candidate biomarkers were significantly different between MPSIVA and unaffected individuals. Of these, five also changed significantly in response to ERT: alpha-1-antitrypsin, eotaxin, lipoprotein(a), matrix metalloprotein (MMP)-2, and serum amyloid P. Three of these were significantly lower in MPSIVA individuals versus unaffected controls and were increased during ERT: alpha-1-antitrypsin, lipoprotein(a), and serum amyloid P.
Candidate biomarkers alpha-1-antitrypsin, lipoprotein(a), and serum amyloid P may be suitable markers, in addition to urinary KS, to follow the response to ERT in MPSIVA patients.
Abstract Background Extensive research has demonstrated the importance of traditional cardiovascular risk factors in predicting acute coronary events. Our main objective was to evaluate the ...relationship between traditional risk factors and the presence of obstructive coronary artery disease (CAD), and to explore potential differences in men vs women. Methods An observational study was conducted in a population-based cohort of stable patients who underwent cardiac catheterization in Ontario, Canada. We examined the relationship of diabetes, hypertension, hyperlipidemia, and smoking with the presence of obstructive CAD in men and women using multivariable logistic regression models. Results Of the 46,490 patients who were included in our study, 61.2% were men and 38.8% were women. We found that 97% of patients with obstructive CAD had at least 1 conventional cardiovascular risk factor. The adjusted odds ratios (ORs) for obstructive CAD in women with diabetes (OR, 1.51), hypertension (OR, 1.38), and smoking (OR, 1.39) were statistically significantly greater than in men (OR, 1.20 for diabetes; OR, 1.08 for hypertension; OR, 1.14 for smoking; P < 0.001). The sex difference was even greater for patients with multiple risk factors. For example, the association with obstructive CAD in women with 4 cardiac risk factors (OR, 4.30; 95% confidence interval, 3.49-5.28) was almost doubled compared with men (OR, 2.26; 95%confidence interval, 1.99-2.57; P < 0.001). Conclusions Almost all patients with stable CAD undergoing cardiac catheterization had at least 1 traditional cardiac risk factor. Importantly, the association between multiple cardiac risk factors and the presence of obstructive CAD is substantially stronger in women than men.
Transcatheter aortic valve implantation (TAVI) has emerged as an important treatment for patients with severe symptomatic aortic stenosis who are at high operative risk, but accurate estimates of ...serious adverse effects in contemporary practice are not available.
To quantify the adverse effects associated with TAVI, and to evaluate whether the type of transcatheter valve and the route of valve implantation are associated with differences in adverse outcomes.
PubMed to 5 May 2012.
All studies that included at least 100 patients who had TAVI and reported at least 1 outcome of interest.
Two reviewers abstracted the data independently. A random-effects model was used to combine data on adverse outcomes and conduct stratified analyses.
A total of 49 studies enrolling 16 063 patients met the inclusion criteria. Overall 30-day and 1-year survival after TAVI were 91.9% (95% CI, 91.1% to 92.8%) and 79.2% (CI, 76.9% to 81.4%), respectively. Heart block requiring permanent pacemaker implantation was the most common adverse outcome (13.1%) and was 5 times more common with the CoreValve (Medtronic, Minneapolis, Minnesota) than the Sapien valve (Edwards Lifesciences, Irving, California) implanted using the transarterial route (25.2% vs. 5.0%, respectively). The overall rate of vascular complications was 10.4% and was highest with transarterial implantation of the Sapien valve (22.3%). Acute renal failure requiring renal replacement therapy was the third most common complication, occurring in 4.9% of patients.
Rates of major vascular complications may be overestimated owing to rapidly evolving TAVI technology.
The most common adverse effects associated with TAVI are heart block, vascular complications, and renal failure. The type of transcatheter valve and the route of implantation are associated with observed variations in the risks for some adverse effects.
Heart and Stroke Foundation of Canada.
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