Immunization with soluble BDC 2.5 T cell receptor-immunoglobulin chimeric protein:antibody specificity and protection of nonobese diabetic mice against adoptive transfer of diabetes by maternal immunization

Particle-Based therapies for antigen specific treatment of type 1 diabetes

Type 1 diabetes mellitus (T1D) is the leading metabolic disorder in children worldwide. Over time, incidence rates have continued to rise with 20 million individuals affected globally by the autoimmune disease. The current standard of care is costly and time-consuming requiring daily injections of exogenous insulin. T1D is mediated by autoimmune effector responses targeting autoantigens expressed on pancreatic islet β-cells. One approach to treat T1D is to skew the immune system away from an effector response by taking an antigen-specific approach to heighten a regulatory response through a therapeutic vaccine. An antigen-specific approach has been shown with soluble agents, but the effects have been limited. Micro or nanoparticles have been used to deliver a variety of therapeutic agents including peptides and immunomodulatory therapies to immune cells. Particle-based systems can be used to deliver cargo into the cell and microparticles can passively target phagocytic cells. Further, surface modification and controlled release of encapsulated cargo can enhance delivery over soluble agents. The induction of antigen-specific immune tolerance is imperative for the treatment of autoimmune diseases such as T1D. This review highlights studies that utilize particle-based platforms for the treatment of T1D.

Current translational and clinical practices in hematopoietic cell and gene therapy

Clinical trials over the last 15 years have demonstrated that cell and gene therapies for cancer, monogenic and infectious disease are feasible and can lead to long-term benefit for patients. However, these trials have been limited to proof-of-principle and were conducted on modest numbers of patients or over long periods of time. In order for these studies to move towards standard practice and commercialization, scalable technologies for the isolation, ex vivo manipulation and delivery of these cells to patients must be developed. Additionally, regulatory strategies and clinical protocols for the collection, creation and delivery of cell products must be generated. In this article we review recent progress in hematopoietic cell and gene therapy, describe some of the current issues facing the field and discuss clinical, technical and regulatory approaches used to navigate the road to product development.

Maternal immunity to insulin does not affect diabetes risk in progeny of non obese diabetic mice

It has been suggested that maternal environment, in particular maternal autoantibodies, modify the risk of developing autoimmune diabetes in offspring. The aim of this study was to determine whether modification of maternal environment and maternal diabetes risk through immunization affects autoimmune diabetes risk in the progeny. The risk of developing insulin antibodies and of developing diabetes was determined in 113 female progeny of non obese diabetic (NOD) dams that were immunized with insulin, control antigen or vehicle before or during pregnancy. Although NOD dams immunized with insulin were rendered diabetes resistant (40% diabetes by age 36 weeks versus 100% in control dams), diabetes development in their female offspring (72%, 26/36) was similar to that in female offspring of dams immunized with glucagon (82%, 22/27) or vehicle (76%, 19/25). Furthermore, no significant differences in diabetes development or insulin autoantibody titres were observed between female progeny of insulin autoantibody positive NOD dams (82% diabetes by age 36 weeks, 18/22), insulin autoantibody negative NOD dams (75%, 41/55), and NOD dams that had antibodies against exogneous insulin (71%, 22/31). The findings suggest that modification of the maternal risk for autoimmune diabetes via antigen-specific immunization is not transferred to progeny and that fetal exposure to insulin autoantibodies does not increase the risk for diabetes development.

Conformational integrity and ligand binding properties of a single chain T-cell receptor expressed in Escherichia coli

We recently showed that a soluble, heterodimeric murine D10 T-cell receptor (TCR) (Valpha2Calpha, Vbeta8.2Cbeta) expressed in insect cells binds both Vbeta8.2-specific bacterial superantigen staphylococcal enterotoxin C2 (SEC2) and a soluble, heterodimeric major histocompatibility complex class II I-Ak.conalbumin peptide complex with a low micromolar affinity. To define further the structural requirements for the TCR/ligand interactions, we have produced in Escherichia coli a soluble, functional D10 single chain (sc) TCR molecule in which the Valpha and Vbeta domains are connected by a flexible peptide linker. Purified and refolded D10 scTCR bound to SEC2 and murine major histocompatibility complex class II I-Ak.conalbumin peptide complex with thermodynamic and kinetic binding constants similar to those measured for the baculovirus-derived heterodimeric D10 TCR suggesting that neither the TCR constant domains nor potential N- or O-linked carbohydrate moieties are necessary for ligand recognition and for expression and proper folding of the D10 scTCR. Purified D10 scTCR remained soluble at concentrations up to 1 mM. Circular dichroism and NMR spectroscopy indicated that D10 scTCR is stabilized predominantly by beta-sheet secondary structure, consistent with its native-like conformation. Because of its limited size, high solubility, and structural integrity, purified D10 scTCR appears to be suitable for structural studies by multidimensional NMR spectroscopy.

Affinity and kinetics of the interactions between an alphabeta T-cell receptor and its superantigen and class II-MHC/peptide ligands

Immune activation is mediated by a specific interaction between the T-cell receptor (TCR) and an antigenic peptide bound to the major histocompatibility complex (MHC). T-cell activation can also be stimulated by superantigens which bind to germline-encoded variable domain sequences of certain TCR beta-chains. We have used a surface plasmon resonance biosensor to characterize the molecular interactions between a class II-restricted alphabeta TCR and its superantigen and MHC/peptide ligands. The extracellular domains of the murine D10 TCR (Valpha2, Vbeta8.2) were expressed in insect cells and secreted as a disulfide-linked heterodimer. In the absence of MHC class II, purified soluble D10 TCR bound to Staphylococcus aureus enterotoxin C2 with an association rate of 1.69+/-0.12 x 10(4)M(-1) sec(-1) and a dissociation rate of 1.9+/-0.47 x 10(-2) sec(-1), giving a dissociation constant of 1.1 microM. Binding of the TCR to S. aureus enterotoxin B was barely detectable and could not be measured accurately due to the rapid dissociation rate. Soluble D10 TCR also bound to a soluble murine MHC class II I-A(k) molecule containing a fused antigenic conalbumin peptide and complementary leucine zipper sequences to facilitate efficient chain pairing. The purified I A(k) chimera specifically stimulated proliferation of the D10 T-cell clone, and bound to immobilized soluble D10 TCR with an association rate of 1.07+/-0.19 x 10(4)M(-1)sec(-1) and a dissociation rate of 2.2+/-0.65 x 10(-2) sec(-1), giving a dissociation constant of 2.1 microM.