Molecular mimics can induce a nonautoaggressive repertoire that preempts induction of autoimmunity.

To determine the role that competition plays in a molecular mimic's capacity to induce autoimmunity, we studied the ability of naïve encephalitogenic T cells to expand in response to agonist altered peptide ligands (APLs), some capable of stimulating both self-directed and exclusively APL-specific T cells. Our results show that although the APLs capable of stimulating exclusively APL-specific T cells are able to expand encephalitogenic T cells in vitro, the encephalitogenic repertoire is effectively outcompeted in vivo when the APL is used as the priming immunogen. Competition as a mechanism was supported by: (i) the demonstration of a population of exclusively APL-specific T cells, (ii) an experiment in which an encephalitogenic T cell population was successfully outcompeted by adoptively transferred naïve T cells, and (iii) demonstrating that the elimination of competing T cells bestowed an APL with the ability to expand naïve encephalitogenic T cells in vivo. In total, these experiments support the existence of a reasonably broad T cell repertoire responsive to a molecular mimic (e.g., a microbial agent), of which the exclusively mimic-specific component tends to focus the immune response on the invading pathogen, whereas the rare cross-reactive, potentially autoreactive T cells are often preempted from becoming involved.

Tarsal shape, size, and articulating surface morphology in adolescent surgically treated clubfoot and their contralateral normal foot.

Despite the inability of radiographic measurements to quantify the 3-dimensional (3D) shape and size of the hindfoot bones affected by the clubfoot pathology, radiographs continue to be used to evaluate treatment efficacy. Advancements in imaging and image analysis allow new quantitative insights to be obtained into bone shape and size. Therefore, this study sought to quantify and compare the 3D size, shape, and articulating surface morphology of the tibia, talus, calcaneus, navicular, and cuboid bones in the adolescent surgically treated unilateral clubfoot and the contralateral normal foot. Anatomic measurements were obtained by geometrically modeling 3D reconstructed magnetic resonance images of the hindfoot tarsals in the feet of 7 adolescents (mean age, 13.0+/-2.8 years). The results showed that the tarsal bones in the surgically treated clubfoot were smaller in volume (20%-36%) and smaller in surface area (16%-28%) than those in the contralateral normal foot. Correspondingly, the size and shape of the articulating surfaces of these bones in the surgically treated clubfoot were also smaller and flatter than those in the contralateral normal foot. Specifically, the mean talar articular surface area was 25% to 40% smaller, the mean talar-tibiotalar articular surface length was 26% smaller, the mean tibiotalar articular surface length difference was 78% smaller, and the mean navicular "flattening index" was 86% larger in the surgically treated clubfoot. These data offer an objective standard that will advance the knowledge of the clubfoot pathology and aid treatment efficacy evaluation.

Three-dimensional in vivo motion of adult hind foot bones.

Knowledge of hind foot bone motion is important for understanding gait as well as various foot pathologies, but the three-dimensional (3D) motion of these bones remains incompletely understood. The purpose of this study was to quantify the motion of the talus, calcaneus, navicular, and cuboid in normal adult feet during open chain quasi-static uniplanar plantar flexion motion. Magnetic resonance images of the right feet of six normal young adult males were taken from which 3D virtual models were made of each hind foot bone. The 3D motion of these models was analyzed. Each hind foot bone rotated in the same plane about half as much as the foot (mean 0.54 degrees of bone rotation per degree of foot motion, range 0.40-0.73 degrees per degree of foot motion as measured relative to the fixed tibia). Talar motion was primarily uniaxial, but the calcaneus, navicular, and cuboid bones exhibited biplanar (sometimes triplanar) translation in addition to biaxial rotation. Net translational motions of these bones averaged 0.39 mm of bone translation per degree of foot motion (range 0.06-0.62 mm per degree of foot motion). These data reflect the functional anatomy of the foot, extend the findings of prior studies, provide a standard for comparison to patients with congenital or acquired foot deformities, and establish an objective reference for quantitatively assessing the efficacy of various hind foot therapies.

Three-dimensional hindfoot motion in adolescents with surgically treated unilateral clubfoot.

Advances in imaging and computerized analyses have enabled three-dimensional bone motion in the treated clubfoot to be measured precisely. Three-dimensional translations and rotations of the talus, calcaneus, navicular, and cuboid of surgically treated clubfeet were less in magnitude and sometimes different in direction (or without motion in a specific plane) compared with the contralateral normal feet. Surgical techniques used for clubfoot treatment do not restore normal hindfoot bone motion when examined with high-resolution magnetic resonance imaging, computer reconstruction, and image analysis techniques. These data advance the knowledge of hindfoot bone motion and establish a new and quantitative objective.

Nasal instillation of gpMBP can exacerbate murine EAE: effect of mucosal priming is an age-dependent phenomenon.

Nasal installation or oral feeding of antigens can alter the subsequent immune response in animals and humans. Most mucosal treatments with antigens tend to down-regulate disease, inducing full tolerance or immune deviation; however, priming has also been reported. We evaluated the course of experimental autoimmune encephalomyelitis (EAE) in (SJL x B10.PL)F1 mice after nasal instillation of myelin basic protein. There was a tendency towards exacerbation of subsequent disease in animals if they were nasally exposed to gpMBP during the neonatal period (first week of life), compared to exposure during adulthood. Later, at 11 months of age, this tendency to exacerbate disappeared. Our results suggest that mucosal exposure during early life may regularly modulate the anti-self immune response upwards in individuals genetically predisposed to autoimmune diseases.

Protein microarrays guide tolerizing DNA vaccine treatment of autoimmune encephalomyelitis.

The diversity of autoimmune responses poses a formidable challenge to the development of antigen-specific tolerizing therapy. We developed 'myelin proteome' microarrays to profile the evolution of autoantibody responses in experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis (MS). Increased diversity of autoantibody responses in acute EAE predicted a more severe clinical course. Chronic EAE was associated with previously undescribed extensive intra- and intermolecular epitope spreading of autoreactive B-cell responses. Array analysis of autoantigens targeted in acute EAE was used to guide the choice of autoantigen cDNAs to be incorporated into expression plasmids so as to generate tolerizing vaccines. Tolerizing DNA vaccines encoding a greater number of array-determined myelin targets proved superior in treating established EAE and reduced epitope spreading of autoreactive B-cell responses. Proteomic monitoring of autoantibody responses provides a useful approach to monitor autoimmune disease and to develop and tailor disease- and patient-specific tolerizing DNA vaccines.

Autoreactive T cells can be protected from tolerance induction through competition by flanking determinants for access to class II MHC.

It is not clear why the N-terminal autoantigenic determinant of myelin basic protein (MBP), Ac1-9, is dominant in the B1O.PL (H-2(u)) mouse, given its weak I-A(u)-MHC binding affinity. Similarly, how do high-affinity T cells specific for this determinant avoid negative selection? Because the MBP:1-9 sequence is embryonically expressed uniquely in the context of Golli-MBP, determinants were sought within the contiguous N-terminal "Golli" region that could out-compete MBP:1-9 for MHC binding, and thereby prevent negative selection of the public response to Ac1-9, shown here to be comprised of a V beta 8.2J beta 2.7 and a V beta 8.2J beta 2.4 expansion. Specifically, we demonstrate that Ac1-9 itself can be an effective inducer of central tolerance induction; however, in the context of Golli-MBP, Ac1-9 is flanked by determinants which prevent its display to autoreactive T cells. Our data support competitive capture as a means of protecting high-affinity, autoreactive T cells from central tolerance induction.

The Wistar Kyoto (RT1(l)) rat is resistant to myelin basic protein-induced experimental autoimmune encephalomyelitis: comparison with the susceptible Lewis (RT1(l)) strain with regard to the MBP-directed CD4+ T cell repertoire and its regulation.

Here, we demonstrate that the Wistar Kyoto (WKY/NHsd) rat, which bears the same RT1(l) haplotype as the experimental autoimmune encephalomyelitis (EAE)-susceptible Lewis rat strain, is highly resistant to myelin basic protein (MBP)-induced EAE. No differences between Lewis and WKY strains were found in T cell proliferative specificity or the use of Vbeta8.2 T cell receptors in response to MBP. A Th2 cytokine bias correlated with WKY's EAE resistance. MBP challenge of WKY-into-Lewis adoptive transfer recipients produced a novel biepisodic EAE. The WKY strain should be useful in studies of many tissue-specific autoimmune diseases to which the Lewis rat is susceptible.