A Novel Dimeric Inhibitor Targeting Beta2GPI in Beta2GPI/Antibody Complexes Implicated in Antiphospholipid Syndrome

Background: b2GPI is a major antigen for autoantibodies associated with antiphospholipid syndrome (APS), an autoimmune disease characterized by thrombosis and recurrent pregnancy loss. Only the dimeric form of b2GPI generated by anti-b2GPI antibodies is pathologically important, in contrast to monomeric b2GPI which is abundant in plasma. Principal Findings: We created a dimeric inhibitor, A1-A1, to selectively target b2GPI in b2GPI/antibody complexes. To make this inhibitor, we isolated the first ligand-binding module from ApoER2 (A1) and connected two A1 modules with a flexible linker. A1-A1 interferes with two pathologically important interactions in APS, the binding of b2GPI/antibody complexes with anionic phospholipids and ApoER2. We compared the efficiency of A1-A1 to monomeric A1 for inhibition of the binding of b2GPI/antibody complexes to anionic phospholipids. We tested the inhibition of b2GPI present in human serum, b2GPI purified from human plasma and the individual domain V of b2GPI. We demonstrated that when b2GPI/antibody complexes are formed, A1-A1 is much more effective than A1 in inhibition of the binding of b2GPI to cardiolipin, regardless of the source of b2GPI. Similarly, A1-A1 strongly inhibits the binding of dimerized domain V of b2GPI to cardiolipin compared to the monomeric A1 inhibitor. In the absence of anti-b2GPI antibodies, both A1-A1 and A1 only weakly inhibit the binding of pathologically inactive monomeric b2GPI to cardiolipin. Conclusions: Our results suggest that the approach of using a dimeric inhibitor to block b2GPI in the pathologica

FLAIR* to visualize veins in white matter lesions: A new tool for the diagnosis of multiple sclerosis?

Royal College of Radiologists (pump priming grant to RJPS). MEM is partly funded (20%) by the Barts and the London National Institute for Health Research Cardiovascular Biomedical Research Unit. Additional study support provided by the Intramural Research Program of the National Institute of Neurological Disorders and Stroke, USA

Functional consequences of HLA-DQ8 homozygosity versus heterozygosity for islet autoimmunity in type 1 diabetes

Human leukocyte antigen (HLA) class II haplotypes are established risk factors in type 1 diabetes (T1D). The heterozygous DQ2/8 genotype confers the highest risk, whereas the DQ6/8 genotype is protective. We hypothesized that DQ2/8 trans-molecules composed of α and β chains from DQ2 and DQ8 express unique β-cell epitopes, whereas DQ6 may interfere with peptide binding to DQ8. Here we show that a single insulin epitope (InsB13-21) within the T1D prototype antigenic InsB6-22 peptide can bind to both cis- and trans-dimers, although these molecules display different peptide binding patterns. DQ6 binds a distinct insulin epitope (InsB6-14). The phenotype of DQ8-restricted T cells from a T1D patient changed from proinflammatory to anti-inflammatory in the presence of DQ6. Our data provide new insights into both susceptible and protective mechanism of DQ, where protecting HLA molecules bind autoantigens in a different (competing) binding register leading to 'epitope stealing', thereby inducing a regulatory, rather than a pathogenic immune response.Transplantation and autoimmunit

Effect of calendar age on physical performance: A comparison of standard clinical measures with instrumented measures in middle-aged to older adults

Background: Decline in physical performance is highly prevalent during aging. Identification of sensitive markers of age-related changes in physical performance is important for early detection, development of therapeutic strategies and insight into underlying mechanisms. We studied the association of calendar age and familial longevity with standard clinical and instrumented measures of physical performance in a cohort of healthy middle-aged to older adults. Methods: Cross-sectional analysis within the Leiden Longevity Study consisting of offspring of nonagenarian siblings and their partners (n = 300, mean age (SD) 65.3 (6.7) years). Standard clinical measures were 25-meter walking speed and total duration of the chair stand test (CST). Instrumented measures were determined using a body fixed sensor. Dependence of physical performance on calendar age and familial longevity (offspring versus partner status) was analyzed using linear and logistic regression, respectively, adjusted for gender and height. Results: Higher calendar age was associated with slower walking speed and longer duration of the CST (standardized β (95% CI) -.024 (-.042; -.006) and .035 (.014;.056), respectively). Instrumented measures showed similar effect sizes with strongest associations for gait stability and symmetry in mediolateral direction and for the extension and flexion phase of sit-to-stand and stand-to-sit transfers, respectively. No differences were observed between offspring of nonagenarian siblings and their partners. Conclusions: Standard clinical and instrumented measures of physical performance are associated with similar effect size to age-related changes in physical performance observable from middle age. The potential added value of instrumented measures for understanding underlying mechanisms requires further attention

Autoimmunity against a defective ribosomal insulin gene product in type 1 diabetes

Identification of epitopes that are recognized by diabetogenic T cells and cause selective beta cell destruction in type 1 diabetes (T1D) has focused on peptides originating from native beta cell proteins. Translational errors represent a major potential source of antigenic peptides to which central immune tolerance is lacking. Here, we describe an alternative open reading frame within human insulin mRNA encoding a highly immunogenic polypeptide that is targeted by T cells in T1D patients. We show that cytotoxic T cells directed against the N-terminal peptide of this nonconventional product are present in the circulation of individuals diagnosed with T1D, and we provide direct evidence that such CD8+ T cells are capable of killing human beta cells and thereby may be diabetogenic. This study reveals a new source of nonconventional polypeptides that act as self-epitopes in clinical autoimmune disease

Automated approach for quantifying the repeated sit-to-stand using one body fixed sensor in young and older adults

<p>Much is known about the sit-to-stand (STS) and its biomechanics. Currently, however, there is little opportunity for instrumented quantification of the STS as part of screening or diagnosis in clinical practice. The objectives of the present study were to describe the feasibility of using an automated approach for quantifying the STS using one sensor location and to start testing the discriminative validity of this approach by comparing older and younger adults. 15 older subjects recruited from a residential care home and 16 young adults performed 5 repeated sit-to-stand and stand-to-sit movements. They were instrumented with a small and lightweight measurement system (DynaPort (R)) containing 1 triaxial seismic accelerometer and 3 uniaxial gyroscopes fixed in a belt around the waist. Durations of the (sub-)phases of the STS were analyzed and maximum angular velocities were determined. All successful STS cycles were automatically detected without any errors. The STS duration in the older adults was significantly longer and more variable in all phases (i.e., sit-to-stand, standing, stand-to-sit and sitting) compared to the young adults. Older adults also exhibited lower trunk flexion angular velocity. The results of this first fully automated analysis of instrumented repeated STS movements demonstrate that several STS parameters can be identified that provide a basis for a more precise, quantitative study of STS performance in clinical practice. (C) 2012 Elsevier B.V. All rights reserved.</p>