Antibody dissociation rates are predictive of neutralizing antibody (NAb) course: a comparison of interferon beta-1b-treated Multiple Sclerosis (MS) patients with transient versus sustained NAbs.

A proportion of multiple sclerosis (MS) patients treated with interferon-ß (IFNß) develop neutralizing antibodies (NAbs), which can reduce therapeutic efficacy. In the Betaseron/Betaferon in Newly Emerging MS for Initial Treatment (BENEFIT) study, 88/277 patients developed NAbs, 48 having transient positivity and 29 having sustained positivity. This study aimed to investigate the antibody binding characteristics of serial sera in a subset of these two patient groups. Using Biacore™, a surface plasmon resonance-based technology that monitors biomolecular interactions in real time, we immobilized pure IFNß-1b and analyzed antibody binding responses and dissociation rates of these sera. NAb titers correlated directly with binding responses and inversely with dissociation rates, and sera from sustained NAb patients demonstrated significantly higher binding responses and slower dissociation rates than sera from transient NAb patients. Thus, transient and sustained NAbs are quantitatively and qualitatively different, and interestingly, binding responses and dissociation rates at month 12 could predict the NAb course.

Intermolecular transmission of superoxide dismutase 1 misfolding in living cells.

Human wild-type superoxide dismutase-1 (wtSOD1) is known to coaggregate with mutant SOD1 in familial amyotrophic lateral sclerosis (FALS), in double transgenic models of FALS, and in cell culture systems, but the structural determinants of this process are unclear. Here we molecularly dissect the effects of intracellular and cell-free obligately misfolded SOD1 mutant proteins on natively structured wild-type SOD1. Expression of the enzymatically inactive, natural familial ALS SOD1 mutations G127X and G85R in human mesenchymal and neural cell lines induces misfolding of wild-type natively structured SOD1, as indicated by: acquisition of immunoreactivity with SOD1 misfolding-specific monoclonal antibodies; markedly enhanced protease sensitivity suggestive of structural loosening; and nonnative disulfide-linked oligomer and multimer formation. Expression of G127X and G85R in mouse cell lines did not induce misfolding of murine wtSOD1, and a species restriction element for human wtSOD1 conversion was mapped to a region of sequence divergence in loop II and ß-strand 3 of the SOD1 ß-barrel (residues 24-36), then further refined surprisingly to a single tryptophan residue at codon 32 (W32) in human SOD1. Time course experiments enabled by W32 restriction revealed that G127X and misfolded wtSOD1 can induce misfolding of cell-endogenous wtSOD1. Finally, aggregated recombinant G127X is capable of inducing misfolding and protease sensitivity of recombinant human wtSOD1 in a cell-free system containing reducing and chelating agents; cell-free wtSOD1 conversion was also restricted by W32. These observations demonstrate that misfolded SOD1 can induce misfolding of natively structured wtSOD1 in a physiological intracellular milieu, consistent with a direct protein-protein interaction.

De Novo Design of a ß-Helix Tau Protein Scaffold: An Oligomer-Selective Vaccine Immunogen Candidate for Alzheimer's Disease.

Tau pathology is associated with many neurodegenerative disorders, including Alzheimer's disease (AD), where the spatio-temporal pattern of tau neurofibrillary tangles strongly correlates with disease progression, which motivates therapeutics selective for misfolded tau. Here, we introduce a new avidity-enhanced, multi-epitope approach for protein-misfolding immunogen design, which is predicted to mimic the conformational state of an exposed epitope in toxic tau oligomers. A predicted oligomer-selective tau epitope 343KLDFK347 was scaffolded by designing a ß-helix structure that incorporated multiple instances of the 16-residue tau fragment 339VKSEKLDFKDRVQSKI354. Large-scale conformational ensemble analyses involving Jensen-Shannon Divergence and the embedding depth D showed that the multi-epitope scaffolding approach, employed in designing the ß-helix scaffold, was predicted to better discriminate toxic tau oligomers than other "monovalent" strategies utilizing a single instance of an epitope for vaccine immunogen design. Using Rosetta, 10,000 sequences were designed and screened for the linker portions of the ß-helix scaffold, along with a C-terminal stabilizing α-helix that interacts with the linkers, to optimize the folded structure and stability of the scaffold. Structures were ranked by energy, and the lowest 1% (82 unique sequences) were verified using AlphaFold. Several selection criteria involving AlphaFold are implemented to obtain a lead-designed sequence. The structure was further predicted to have free energetic stability by using Hamiltonian replica exchange molecular dynamics (MD) simulations. The synthesized ß-helix scaffold showed direct binding in surface plasmon resonance (SPR) experiments to several antibodies that were raised to the structured epitope using a designed cyclic peptide. Moreover, the strength of binding of these antibodies to in vitro tau oligomers correlated with the strength of binding to the ß-helix construct, suggesting that the construct presents an oligomer-like conformation and may thus constitute an effective oligomer-selective immunogen.

A novel multiplex electrochemiluminescent immunoassay for detection and quantification of anti-SARS-CoV-2 IgG and anti-seasonal endemic human coronavirus IgG.

BACKGROUND: Multiplex immunoassays capture a comprehensive profile of the humoral response against SARS-CoV-2 and human endemic coronaviruses. We validated a multiplex panel (V-PLEX Panel 2) from Meso Scale Diagnostics targeting antibodies against nine coronavirus antigens. Performance was compared against alternative single- and multi-antigen immunoassays. METHODS: Sera collected for clinical or public health testing from 2018 to 2020 (n = 135) were used to compare all tested platforms, and inter-test agreement was assessed by Cohen's kappa coefficient. Sample category (positive/negative) was assigned based on collection date relative to the index case in Canada, and SARS-CoV-2 PCR and serology results. 117 out of the 135 samples (31 positive, 86 negative) were assigned a category and were used to calculate sensitivity and specificity, with MSD's test results based upon manufacturer-set cut-offs. RESULTS: We observed SARS-CoV-2 target sensitivities of 100% and specificities >94% for all antigens (RBD, Nucleocapsid, Spike) in V-PLEX Panel 2. When targets were combined, we found a SARS-CoV-2 sensitivity of 100% and specificity of 98.8% with no difference in performance compared to clinical assays, and Cohen's kappa ranging from 0.798 to 0.945 compared to surface plasmon resonance imaging (SPRi). Quantitative measurements of antibodies against the Spike protein of endemic human coronaviruses were concordant with SPRi. CONCLUSION: Meso Scale Diagnostics' V-PLEX Coronavirus Panel 2 allows for highly sensitive and specific detection of anti-coronavirus IgG, and is concordant with other serological assays for detection of antibodies against SARS-CoV-2 and the endemic human coronaviruses, making it a good tool for humoral response characterization after both infection and vaccination.

Rational Generation of Monoclonal Antibodies Selective for Pathogenic Forms of Alpha-Synuclein.

Misfolded toxic forms of alpha-synuclein (α-Syn) have been implicated in the pathogenesis of synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). The α-Syn oligomers and soluble fibrils have been shown to mediate neurotoxicity and cell-to-cell propagation of pathology. To generate antibodies capable of selectively targeting pathogenic forms of α-Syn, computational modeling was used to predict conformational epitopes likely to become exposed on oligomers and small soluble fibrils, but not on monomers or fully formed insoluble fibrils. Cyclic peptide scaffolds reproducing these conformational epitopes exhibited neurotoxicity and seeding activity, indicating their biological relevance. Immunization with the conformational epitopes gave rise to monoclonal antibodies (mAbs) with the desired binding profile showing selectivity for toxic α-Syn oligomers and soluble fibrils, with little or no reactivity with monomers, physiologic tetramers, or Lewy bodies. Recognition of naturally occurring soluble α-Syn aggregates in brain extracts from DLB and MSA patients was confirmed by surface plasmon resonance (SPR). In addition, the mAbs inhibited the seeding activity of sonicated pre-formed fibrils (PFFs) in a thioflavin-T fluorescence-based aggregation assay. In neuronal cultures, the mAbs protected primary rat neurons from toxic α-Syn oligomers, reduced the uptake of PFFs, and inhibited the induction of pathogenic phosphorylated aggregates of endogenous α-Syn. Protective antibodies selective for pathogenic species of α-Syn, as opposed to pan α-Syn reactivity, are expected to provide enhanced safety and therapeutic potency by preserving normal α-Syn function and minimizing the diversion of active antibody from the target by the more abundant non-toxic forms of α-Syn in the circulation and central nervous system.

A method for systematically ranking therapeutic drug candidates using multiple uncertain screening criteria.

Multiple different screening tests for candidate leads in drug development may often yield conflicting or ambiguous results, sometimes making the selection of leads a nontrivial maximum-likelihood ranking problem. Here, we employ methods from the field of multiple criteria decision making (MCDM) to the problem of screening candidate antibody therapeutics. We employ the SMAA-TOPSIS method to rank a large cohort of antibodies using up to eight weighted screening criteria, in order to find lead candidate therapeutics for Alzheimer's disease, and determine their robustness to both uncertainty in screening measurements, as well as uncertainty in the user-defined weights of importance attributed to each screening criterion. To choose lead candidates and measure the confidence in their ranking, we propose two new quantities, the Retention Probability and the Topness, as robust measures for ranking. This method may enable more systematic screening of candidate therapeutics when it becomes difficult intuitively to process multi-variate screening data that distinguishes candidates, so that additional candidates may be exposed as potential leads, increasing the likelihood of success in downstream clinical trials. The method properly identifies true positives and true negatives from synthetic data, its predictions correlate well with known clinically approved antibodies vs. those still in trials, and it allows for ranking analyses using antibody developability profiles in the literature. We provide a webserver where users can apply the method to their own data: http://bjork.phas.ubc.ca.

MuSK not MNGIE: Atypical MuSK-antibody myasthenia presenting as a genetic disorder.

Myasthenia gravis is a treatable autoimmune disease caused by autoantibodies directed against membrane proteins at the neuromuscular junction. While acetylcholine receptor antibodies are most common, a minority of patients have antibodies directed against muscle-specific kinase (MuSK-antibody). Differentiating features often include subacute onset and rapid progression of bulbar, respiratory and neck extensor muscles, with sparing of distal appendicular muscles, most commonly in middle-aged females. Here we present an atypical presentation of MuSK-antibody myasthenic syndrome in a young male consisting of a gradual-onset, insidiously-progressive, non-fatigable and non-fluctuating ocular, bulbar and oesophageal weakness, with a normal frontalis single fibre EMG. This case clinically resembled a mitochondrial myopathy (Mitochondrial Neurogastrointestinal Encephalopathy-MNGIE) with a poor prognosis. Because of the atypical presentation, MuSK antibodies were identified very late in the disease course, at which point the patient responded very well to immunotherapy. We report an unusual presentation of an uncommon but treatable condition, illustrating significant phenotypic heterogeneity possible in MuSK-antibody myasthenic syndrome.

Development of an α-synuclein knockdown peptide and evaluation of its efficacy in Parkinson's disease models.

Convincing evidence supports the premise that reducing α-synuclein levels may be an effective therapy for Parkinson's disease (PD); however, there has been lack of a clinically applicable α-synuclein reducing therapeutic strategy. This study was undertaken to develop a blood-brain barrier and plasma membrane-permeable α-synuclein knockdown peptide, Tat-ßsyn-degron, that may have therapeutic potential. The peptide effectively reduced the level of α-synuclein via proteasomal degradation both in cell cultures and in animals. Tat-ßsyn-degron decreased α-synuclein aggregates and microglial activation in an α-synuclein pre-formed fibril model of spreading synucleinopathy in transgenic mice overexpressing human A53T α-synuclein. Moreover, Tat-ßsyn-degron reduced α-synuclein levels and significantly decreased the parkinsonian toxin-induced neuronal damage and motor impairment in a mouse toxicity model of PD. These results show the promising efficacy of Tat-ßsyn-degron in two different animal models of PD and suggest its potential use as an effective PD therapeutic that directly targets the disease-causing process.

Molecular interactions between monoclonal oligomer-specific antibody 5E3 and its amyloid beta cognates.

Oligomeric amyloid ß (Aß) is currently considered the most neurotoxic form of the Aß peptide implicated in Alzheimer's disease (AD). The molecular structures of the oligomers have remained mostly unknown due to their transient nature. As a result, the molecular mechanisms of interactions between conformation-specific antibodies and their Aß oligomer (AßO) cognates are not well understood. A monoclonal conformation-specific antibody, m5E3, was raised against a structural epitope of Aß oligomers. m5E3 binds to AßOs with high affinity, but not to Aß monomers or fibrils. In this study, a computational model of the variable fragment (Fv) of the m5E3 antibody (Fv5E3) is introduced. We further employ docking and molecular dynamics simulations to determine the molecular details of the antibody-oligomer interactions, and to classify the AßOs as Fv5E3-positives and negatives, and to provide a rationale for the low affinity of Fv5E3 for fibrils. This information will help us to perform site-directed mutagenesis on the m5E3 antibody to improve its specificity and affinity toward oligomeric Aß species. We also provide evidence for the possible capability of the m5E3 antibody to disaggregate AßOs and to fragment protofilaments.

Therapeutic vaccines for amyotrophic lateral sclerosis directed against disease specific epitopes of superoxide dismutase 1.

Emerging evidence suggests seeding and prion-like propagation of mutant Superoxide Dismutase 1 (SOD1) misfolding to be a potential mechanism for ALS pathogenesis and progression. Immuno-targeting of misfolded SOD1 has shown positive clinical outcomes in mutant SOD1 transgenic mice. However, a major challenge in developing active immunotherapies for proteinopathies such as ALS is the design of immunogens enabling exclusive recognition of pathogenic species of a self-protein. Ideally, one would achieve a robust antibody response against the disease-misfolded protein while sparing the natively folded conformer to avoid inducing deleterious autoimmune complications, or inhibiting its normal function. Using a motor neuron disease mouse model expressing human SOD1-G37R, we herein report the immunogenicity and therapeutic efficacy of two ALS vaccines, tgG-DSE2lim and tgG-DSE5b, based on the notion that native SOD1 would undergo early unfolding in disease to present "disease specific epitopes" (DSE). Both vaccines elicited rapid, robust, and well-sustained epitope-specific antibody responses with a desirable Th2-biased immune response. Both vaccines significantly extended the life expectancy of hSOD1G37R mice, with tgG-DSE2lim displaying greater protection than tgG-DSE5b at earlier pre-symptomatic stage. tgG-DSE5b, but not tgG-DSE2lim, significantly delayed disease onset and appreciably slowed disease progression. This implies that conformationally distinct species of misfolded SOD1 may derive from the same mutation, thereby modifying disease phenotypes in a different fashion. Our results validate the rationale for conformation-based immuno-targeting of misfolded SOD1 as a promising therapeutic strategy to slow or even halt disease progression in familial ALS associated with SOD1 mutations, as well as a prophylactic intervention for carriers of SOD1 mutations. Our study not only provides important proof-of-principle data for the development of a safe and effective human therapeutic/prophylactic ALS vaccine against misfolded SOD1, but also predicts a great potential to extend our DSE-based vaccination approach to other types of ALS, such as those associated with TDP-43 proteinopathies.

A Rationally Designed Humanized Antibody Selective for Amyloid Beta Oligomers in Alzheimer's Disease.

Advances in the understanding of Alzheimer's disease (AD) suggest that pathogenesis is not directly related to plaque burden, but rather to soluble toxic amyloid-beta oligomers (AßO). Therapeutic antibodies targeting Aß monomers and/or plaque have shown limited efficacy and dose-limiting adverse events in clinical trials. These findings suggest that antibodies capable of selectively neutralizing toxic AßO may achieve improved efficacy and safety. To this end, we generated monoclonal antibodies against a conformational Aß epitope predicted by computational modeling to be presented on toxic AßO but not monomers or fibrils. The resulting lead antibody, PMN310, showed the desired AßO-selective binding profile. In vitro, PMN310 inhibited AßO propagation and toxicity. In vivo, PMN310 prevented AßO-induced loss of memory formation and reduced synaptic loss and inflammation. A humanized version (huPMN310) compared favorably to other Aß-directed antibodies showing a lack of adverse event-associated binding to Aß deposits in AD brains, and greater selective binding to AßO-enriched AD brain fractions that contain synaptotoxic Aß species. Systemic administration of huPMN310 in mice resulted in brain exposure and kinetics comparable to those of other therapeutic human monoclonal antibodies. Greater selectivity for AßO and the potential to safely administer high doses of huPMN310 are expected to result in enhanced safety and therapeutic potency.

CHIMERA repetitive mild traumatic brain injury induces chronic behavioural and neuropathological phenotypes in wild-type and APP/PS1 mice.

BACKGROUND: The annual incidence of traumatic brain injury (TBI) in the United States is over 2.5 million, with approximately 3-5 million people living with chronic sequelae. Compared with moderate-severe TBI, the long-term effects of mild TBI (mTBI) are less understood but important to address, particularly for contact sport athletes and military personnel who have high mTBI exposure. The purpose of this study was to determine the behavioural and neuropathological phenotypes induced by the Closed-Head Impact Model of Engineered Rotational Acceleration (CHIMERA) model of mTBI in both wild-type (WT) and APP/PS1 mice up to 8 months post-injury. METHODS: Male WT and APP/PS1 littermates were randomized to sham or repetitive mild TBI (rmTBI; 2 × 0.5 J impacts 24 h apart) groups at 5.7 months of age. Animals were assessed up to 8 months post-injury for acute neurological deficits using the loss of righting reflex (LRR) and Neurological Severity Score (NSS) tasks, and chronic behavioural changes using the passive avoidance (PA), Barnes maze (BM), elevated plus maze (EPM) and rotarod (RR) tasks. Neuropathological assessments included white matter damage; grey matter inflammation; and measures of Aß levels, deposition, and aducanumab binding activity. RESULTS: The very mild CHIMERA rmTBI conditions used here produced no significant acute neurological or motor deficits in WT and APP/PS1 mice, but they profoundly inhibited extinction of fear memory specifically in APP/PS1 mice over the 8-month assessment period. Spatial learning and memory were affected by both injury and genotype. Anxiety and risk-taking behaviour were affected by injury but not genotype. CHIMERA rmTBI induced chronic white matter microgliosis, axonal injury and astrogliosis independent of genotype in the optic tract but not the corpus callosum, and it altered microgliosis in APP/PS1 amygdala and hippocampus. Finally, rmTBI did not alter long-term tau, Aß or amyloid levels, but it increased aducanumab binding activity. CONCLUSIONS: CHIMERA is a useful model to investigate the chronic consequences of rmTBI, including behavioural abnormalities consistent with features of post-traumatic stress disorder and inflammation of both white and grey matter. The presence of human Aß greatly modified extinction of fear memory after rmTBI.

Validating parameters of a luciferase reporter gene assay to measure neutralizing antibodies to IFNbeta in multiple sclerosis patients.

Neutralizing antibodies (NAbs) can occur in some multiple sclerosis (MS) patients receiving interferon beta (IFNbeta) therapy. NAbs reduce drug bioavailabity and high NAb titers reduce drug efficacy. We describe the validation of the R. Farrell and G. Giovannoni luciferase reporter gene assay to measure NAbs to INFbeta. We assayed 163 sera from IFNbeta treated MS patients with an optimized luciferase method and compared the results to those obtained with the reference cytopathic effect (CPE) method using A549 cells and an encephalomyocarditis virus (EMCV). Binding antibodies (BAbs) were measured using a capture ELISA as a screening test for NAbs in the CPE assay. NAb status measured by the luciferase and the ELISA/CPE method did not yield a significant difference. Log10 NAb titers obtained from the luciferase assay and the A549/EMCV CPE methods correlated very well. The inter-assay coefficient of variation for titers was between 17.8-29.3%, and the intra-assay coefficient of variation was between 6.3-15.2%. The luciferase assay is reliable, appropriately sensitive and requires less time than the currently available NAb methods.

A Rational Structured Epitope Defines a Distinct Subclass of Toxic Amyloid-beta Oligomers.

Oligomers of amyloid-ß (AßO) are deemed key in synaptotoxicity and amyloid seeding of Alzheimer's disease (AD). However, the heterogeneous and dynamic nature of AßO and inadequate markers for AßO subtypes have stymied effective AßO identification and therapeutic targeting in vivo. We identified an AßO-subclass epitope defined by differential solvent orientation of the lysine 28 side chain in a constrained loop of serine-asparagine-lysine (cSNK), rarely displayed in molecular dynamics simulations of monomer and fibril ensembles. A mouse monoclonal antibody targeting AßOcSNK recognizes ∼50-60 kDa SDS-resistant soluble Aß assemblages in AD brain and prolongs the lag phase of Aß aggregation in vitro. Acute peripheral infusion of a murine IgG1 anti-AßOcSNK in two AD mouse models reduced soluble brain Aß aggregates by 20-30%. Chronic cSNK peptide immunization of APP/PS1 mice engendered an anti-AßOcSNK IgG1 response without epitope spreading to Aß monomers or fibrils and was accompanied by preservation of global PSD95 expression and improved cued fear memory. Our data indicate that the oligomer subtype AßOcSNK participates in synaptotoxicity and propagation of Aß aggregation in vitro and in vivo.

The IgG subclass-specificities of anti-IFNbeta antibodies change with time and differ between the IFNbeta products in relapsing remitting multiple sclerosis patients.

Anti-Interferon beta (IFNbeta) antibodies are frequently produced during treatment with IFNbeta in Multiple Sclerosis (MS) patients. In recent years, it has become clear that these antibodies cause a decrease in IFNbeta-induced biomarkers and in IFNbeta clinical efficacy. Anti-IFNbeta antibodies are mainly of the IgG isotype, which consists of 4 subclasses. In this study, we tested whether changes occurred in IgG subclasses over time. A series of sera from 21 IFNbeta-treated patients (11 IFNbeta-1a, 10 IFNbeta-1b) were analysed longitudinally using a capture ELISA. IFNbeta-1a treated patients had a restricted subclass distribution, whilst IFNbeta-1b-treated patients demonstrated a wider distribution. When compared to IFNbeta-1b-treated patients, IFNbeta-1a-treated patients had lower levels of total and subclass-specific IgGs against IFNbeta. In particular, antibody levels were markedly lower in the neutralizing antibody (NAb) negative (-) category of IFNbeta-1a-treated patients in comparison to the NAb-IFNbeta-1b-treated patients. The most striking observation of this study were the very low levels or complete absence of IgG3 subclass-specific antibodies to IFNbeta in IFNbeta-1a-treated patients. This difference in the levels of IgG3 may help to clarify the differences in the overall pattern of development of anti-IFNbeta antibodies in IFNbeta-1a-and IFNbeta-1b-treated patients.

Antigen-specificity of antiretinal antibodies in patients with noninfectious uveitis.

OBJECTIVE: Antiretinal antibodies (ARAs) have previously been described in noninfectious uveitis. However, the antigen specificity of these ARAs has not been investigated. The purpose of this study was to identify antigen-specific ARAs in noninfectious uveitis. METHODS: A total of 18 patients with noninfectious uveitis were enrolled. Surface plasmon resonance was used to measure binding responses of patient and control sera against several uveitogenic proteins: recoverin, S-antigen, interphotoreceptor retinoid binding (IRBP), retinal-pigment-epithelium-specific 65-kDa protein (RPE65), tyrosinase-related protein 1 (TRYP1), and tyrosinase-related protein 2 (TRYP2). RESULTS: The frequency of ARA positivity against S-antigen, IRBP, RPE65, TYRP1, and TYRP2 in patients with uveitis did not differ significantly from that of normal controls. However, ARA positivity for recoverin was more frequently observed in patients with uveitis (p = 0.002). A total of 10 patients in the uveitis cohort had birdshot chorioretinopathy, and all 10 were positive for anti-recoverin ARAs. CONCLUSIONS: Patients with noninfectious uveitis have increased frequency of ARA positivity against recoverin. This ARA deserves further investigations as a potential biomarker and pathogenic agent in noninfectious uveitis, especially in birdshot chorioretinopathy.

High-density lipoproteins suppress Aß-induced PBMC adhesion to human endothelial cells in bioengineered vessels and in monoculture.

BACKGROUND: Alzheimer's Disease (AD), characterized by accumulation of beta-amyloid (Aß) plaques in the brain, can be caused by age-related failures to clear Aß from the brain through pathways that involve the cerebrovasculature. Vascular risk factors are known to increase AD risk, but less is known about potential protective factors. We hypothesize that high-density lipoproteins (HDL) may protect against AD, as HDL have vasoprotective properties that are well described for peripheral vessels. Epidemiological studies suggest that HDL is associated with reduced AD risk, and animal model studies support a beneficial role for HDL in selectively reducing cerebrovascular amyloid deposition and neuroinflammation. However, the mechanism by which HDL may protect the cerebrovascular endothelium in the context of AD is not understood. METHODS: We used peripheral blood mononuclear cell adhesion assays in both a highly novel three dimensional (3D) biomimetic model of the human vasculature composed of primary human endothelial cells (EC) and smooth muscle cells cultured under flow conditions, as well as in monolayer cultures of ECs, to study how HDL protects ECs from the detrimental effects of Aß. RESULTS: Following Aß addition to the abluminal (brain) side of the vessel, we demonstrate that HDL circulated within the lumen attenuates monocyte adhesion to ECs in this biofidelic vascular model. The mechanism by which HDL suppresses Aß-mediated monocyte adhesion to ECs was investigated using monotypic EC cultures. We show that HDL reduces Aß-induced PBMC adhesion to ECs independent of nitric oxide (NO) production, miR-233 and changes in adhesion molecule expression. Rather, HDL acts through scavenger receptor (SR)-BI to block Aß uptake into ECs and, in cell-free assays, can maintain Aß in a soluble state. We confirm the role of SR-BI in our bioengineered human vessel. CONCLUSION: Our results define a novel activity of HDL that suppresses Aß-mediated monocyte adhesion to the cerebrovascular endothelium.

During 3 years treatment of primary progressive multiple sclerosis with glatiramer acetate, specific antibodies switch from IgG1 to IgG4.

In this study we analyzed the humoral immune response to glatiramer acetate in 16 GA-treated primary progressive MS patients and 9 placebo patients from the PROMiSe study. We have demonstrated that all multiple sclerosis patients (n=16) continuously treated with GA for 3 years developed anti-GA antibodies that peaked at month 3 and remained elevated during the whole study. We have also demonstrated that initially GA-reactive antibodies of the IgG1 subclass predominate, peaking at month 9 of therapy, but after 9 months IgG1 decreases while anti-GA antibodies of the IgG4 subclass increase and remain high for the 3 years of follow-up. These results support a shift from Th1 to Th2 in the antibody response to glatiramer acetate treatment.

The prion protein binds thiamine.

Although highly conserved throughout evolution, the exact biological function of the prion protein is still unclear. In an effort to identify the potential biological functions of the prion protein we conducted a small-molecule screening assay using the Syrian hamster prion protein [shPrP(90-232)]. The screen was performed using a library of 149 water-soluble metabolites that are known to pass through the blood-brain barrier. Using a combination of 1D NMR, fluorescence quenching and surface plasmon resonance we identified thiamine (vitamin B1) as a specific prion ligand with a binding constant of ~60 µM. Subsequent studies showed that this interaction is evolutionarily conserved, with similar binding constants being seen for mouse, hamster and human prions. Various protein construct lengths, both with and without the unstructured N-terminal region in the presence and absence of copper, were examined. This indicates that the N-terminus has no influence on the protein's ability to interact with thiamine. In addition to thiamine, the more biologically abundant forms of vitamin B1 (thiamine monophosphate and thiamine diphosphate) were also found to bind the prion protein with similar affinity. Heteronuclear NMR experiments were used to determine thiamine's interaction site, which is located between helix 1 and the preceding loop. These data, in conjunction with computer-aided docking and molecular dynamics, were used to model the thiamine-binding pharmacophore and a comparison with other thiamine binding proteins was performed to reveal the common features of interaction.

A biosensor-based characterization of the affinity maturation of the immune response against interferon-beta and correlations with neutralizing antibodies in treated multiple sclerosis patients.

The study of antibodies against Interferon-beta (IFN-beta) in treated multiple sclerosis (MS) patients has focused primarily on detection and quantification, with no single method of detection providing a comprehensive characterization. We assessed serial samples of 18 MS patients, treated with IFN-beta for between 66 and 198 months, to characterize the affinity maturation of these antibodies using a biosensor-based approach (Biacore). Biacore utilizes the principles of surface plasmon resonance (SPR) with data from the dissociation phase of the antigen-antibody reaction being inversely proportional to relative antibody affinity. In patients with neutralizing antibodies (NAbs+), mean antibody dissociation rates decreased from 0.00118 +/- 0.00030 s(-1) at month 6 to 0.00021 +/- 0.00008 s(-1) at month 36, followed by a slight increase to 0.00027 +/- 0.00003 s(-1) at month 60. In NAb- patients, mean antibody dissociation rates decreased only very slightly from 0.00130 +/- 0.00025 s(-1) to 0.00105 +/- 0.00020 s(-1) at month 18, followed by a gradual increase to 0.00243 +/- 0.00099 s(-1) at month 60. Our study shows little improvement in antibody affinity in NAb- patients, in contrast to a marked increase in antibody affinity over time in NAb+ patients with a significant correlation between NAb titers and relative antibody dissociation rates (Spearman's correlation, R(2) = -0.374, p < 0.001). The evaluation of relative antibody affinities will contribute to a thorough understanding of the anti-IFN-beta antibody response.