The normal functioning immune system is programmed to attack foreign pathogens and other foreign proteins while maintaining tolerance to self-proteins. The mechanisms by which tolerance is broken in the initiation of autoimmunity are not completely understood. In the present study, mice immunized with the murine cytochrome c peptide 90 -104 showed no response by the B or T cell compartments. However, immunization with the isoaspartyl form of this peptide, where the linkage of Asp 93 to Leu 94 occurs through the ␤-carboxyl group, resulted in strong B and T cell autoimmune responses. Antibodies elicited by immunization with the isoaspartyl form of self-peptide were cross-reactive in binding to both isoforms of cytochrome c peptide and to native cytochrome c self-protein. In a similar manner, immunization of mice with the isoaspartyl form of a peptide autoantigen of human systemic lupus erythematosus (SLE) resulted in strong B and T cell responses while mice maintained tolerance to the normal aspartyl form of self-antigen. Isoaspartyl linkages within proteins are enhanced in aging and stressed cells and arise under physiological conditions. These posttranslationally modified peptides may serve as an early immunologic stimulus in autoimmune disease.The immune system has evolved to be tolerant of self-proteins by the deletion of autoreactive cells in the thymus or bone marrow and by the establishment of B and T lymphocyte anergy in the peripheral circulation (1-6). These mechanisms are based on the presentation of a vast array of self-peptides to the lymphoid repertoire. Despite the efforts to instruct the immune system to ignore self-tissues, the appearance of various autoimmune diseases demonstrates that tolerance to self-antigens is not perfect. Flaws in the development of immune tolerance can be revealed by the immunization of animal models with a variety of self-peptides leading to B and T cell autoimmunity as well as autoimmune-mediated pathology (7-12).How tolerance is broken in the initiation of autoimmunity is not completely understood. The immunization of mice with a single self-peptide, the amino-terminal 11 amino acids of myelin basic protein (MBP) 1 in complete Freund's adjuvant can elicit pathology resembling that of human multiple sclerosis (7). The induction of disease requires a post-translationally acetylated form of MBP peptide 1-11. While this disease can be elicited with a single self-peptide or even with T cells of a single specificity, the autoimmune response diversifies to many sites on the MBP over the course of the disease. T cell responses originate with the dominant single self-peptide but rapidly evolve to include other cryptic peptide epitopes within MBP. Similar observations of determinant spreading have been made in murine models of diabetes and systemic lupus erythematosus (SLE), two diseases arising spontaneously in susceptible strains of mice (8,11,13).Antinuclear autoantibodies specific for double-stranded DNA and the U1/Sm ribonucleoprotein particle (snRNP) are diagnostic markers ...

Crystal structures of the Fabs from an autoantibody (BV04-01) with specificity for single-stranded DNA have been determined in the presence and absence of a trinucleotide of deoxythymidylic acid, d(pT)3. Formation of the ligand-protein complex was accompanied by small adjustments in the orientations of the variable (VL and VH) domains. In addition, there were local conformational changes in the first hypervariable loop of the light chain and the third hypervariable loop of the heavy chain, which together with the domain shifts led to an improvement in the complementarity of nucleotide and Fab. The sugar-phosphate chain adopted an extended and "open" conformation, with the base, sugar, and phosphate components available for interactions with the protein. Nucleotide 1 (5'-end) was associated exclusively with the heavy chain, nucleotide 2 was shared by both heavy and light chains, and nucleotide 3 was bound by the light chain. The orientation of phosphate 1 was stabilized by hydrogen bonds with serine H52a and asparagine H53. Phosphate 2 formed an ion pair with arginine H52, but no other charge-charge interactions were observed. Insertion of the side chain of histidine L27d between nucleotides 2 and 3 resulted in a bend in the sugar-phosphate chain. The most dominant contacts with the protein involved the central thymine base, which was immobilized by cooperative stacking and hydrogen bonding interactions. This base was intercalated between a tryptophan ring (no. H100a) from the heavy chain and a tyrosine ring (no. L32) from the light chain. The resulting orientation of thymine was favorable for the simultaneous formation of two hydrogen bonds with the backbone carbonyl oxygen and the side chain hydroxyl group of serine L91 (the thymine atoms were the hydrogen on nitrogen 3 and keto oxygen 4).

Objectives Systemic Juvenile Idiopathic Arthritis (sJIA) is characterized by fevers, rash and arthritis, for which IL1 and IL6 inhibitors appear effective. Pulmonary artery hypertension (PAH), interstitial lung disease (ILD) and alveolar proteinosis (AP) have been recently reported in sJIA patients with increased frequency. Our aim was to characterize and compare these cases to a larger cohort of sJIA patients. Methods sJIA patients who developed PAH, ILD and/or AP were identified through an electronic listserv, and their demographic, sJIA and pulmonary disease characteristics, and medication exposure information were collected. These features were compared to a cohort of sJIA patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry. Results Patients (N=25) were significantly (p<0.05) more likely than the CARRA registry cohort (N=389) to be female, have more systemic features, and to have been exposed to an IL-1 inhibitor, tocilizumab, infliximab, corticosteroids, intravenous immunoglobulin, cyclosporine and cyclophosphamide. Eighty% were diagnosed after 2004. Twenty (80%) patients had MAS during their disease course and 15 (60%) had MAS at pulmonary diagnosis. Sixteen patients had PAH, 5 AP and 7 ILD. Seventeen (68%) patients were taking or recently (≤1 month) discontinued a biologic agent at pulmonary symptom onset; 12 (48%) were taking anti-IL1 therapy (primarily anakinra). Seventeen (68%) patients died at a mean of 8.8 months from pulmonary diagnosis. Conclusions PAH, AP and ILD are under-recognized complications of sJIA which are frequently fatal. These may be the result of severe uncontrolled systemic disease activity, and may be influenced by medication exposure.

Objective To formulate consensus treatment plans (CTPs) for induction therapy of newly-diagnosed proliferative lupus nephritis (LN) in juvenile systemic lupus erythematosus (jSLE). Methods A structured consensus formation process was employed by the members of the Childhood Arthritis and Rheumatology Research Alliance (CARRA) after considering the existing medical evidence and current treatment approaches. Results After an initial Delphi survey (response rate 70%), a 2-day consensus conference, and two follow-up Delphi surveys (response rates 63–79%), consensus was achieved for a limited set of CTPs addressing the induction therapy of proliferative LN. These CTPs were developed for prototypic patients defined by eligibility characteristics, and included immunosuppressive therapy with either mycophenolic acid orally twice per day, or intravenous cyclophosphamide once per month at standardized doses for six months. Additionally, the CTPs describe three options for standardized use of glucocorticoids; including a primarily oral, a mixed oral/intravenous, and a primarily intravenous regimen. There was consensus on measures of effectiveness and safety of the CTPs. The CTPs were well accepted by the pediatric rheumatology providers treating children with LN, and up to 300 children per year in North America are expected to be candidates for the treatment with the CTPs. Conclusion CTPs for induction therapy of proliferative LN in jSLE based on the available scientific evidence and pediatric rheumatology group experience have been developed. Consistent use of the CTPs may improve the prognosis of proliferative LN, and support the conduct of comparative effectiveness studies aimed at optimizing therapeutic strategies for proliferative LN in jSLE.