Publications

We studied the clinical correlations and epitopes of autoantibodies directed to a novel autoantigen, Bicaudal D (BICD2), in systemic sclerosis (SSc) and reviewed its relationship to centromere protein A (CENP-A). 451 SSc sera were tested for anti-BICD2 using a paramagnetic bead immunoassay and then univariate and multivariate logistic regression was used to study the association between anti-BICD2 and demographic and clinical parameters as well as other SSc-related autoantibodies. Epitope mapping was performed on solid phase matrices. 25.7% (116/451) SSc sera were anti-BICD2 positive, of which 19.0% had single specificity anti-BICD2 and 81.0% had other autoantibodies, notably anti-CENP (83/94; 88.3%). Compared to anti-BICD2 negative subjects (335/451), single specificity anti-BICD2 subjects were more likely to have an inflammatory myopathy (IM; 31.8% vs. 9.6%, p = .004) and interstitial lung disease (ILD; 52.4% vs. 29.0%, p = .024). Epitope mapping revealed a serine- and proline-rich nonapeptide SPSPGSSLP comprising amino acids 606–614 of BICD2, shared with CENP-A but not CENP-B. We observed that autoantibodies to BICD2 represent a new biomarker as they were detected in patients without other SSc-specific autoantibodies and were the second most common autoantibody identified in this SSc cohort. Our data indicate that the major cross-reactive epitope is associated with anti-CENP-A but, unlike anti-CENP, single specificity anti-BICD2 antibodies associate with ILD and IM.

Several groups have described the presence of fetal brain-reactive maternal autoantibodies in the plasma of some mothers whose children have autism spectrum disorder (ASD). We previously identified seven autoantigens targeted by these maternal autoantibodies, each of which is expressed at significant levels in the developing brain and has demonstrated roles in typical neurodevelopment. To further understand the binding repertoire of the maternal autoantibodies, as well as the presence of any meaningful differences with respect to the recognition and binding of these ASD-specific autoantibodies to each of these neuronal autoantigens, we utilized overlapping peptide microarrays incubated with maternal plasma samples obtained from the Childhood Autism Risk from Genetics and Environment (CHARGE) Study. In an effort to identify the most commonly recognized (immunodominant) epitope sequences targeted by maternal autoantibodies for each of the seven ASD-specific autoantigens, arrays were screened with plasma from mothers with children across diagnostic groups (ASD and typically developing (TD)) that were positive for at least one antigen by western blot (N = 67) or negative control mothers unreactive to any of the autoantigens (N = 18). Of the 63 peptides identified with the discovery microarrays, at least one immunodominant peptide was successfully identified for each of the seven antigenic proteins using subsequent selective screening microarrays. Furthermore, while limited by our relatively small sample size, there were peptides that were distinctly recognized by autoantibodies relative to diagnosis For example, reactivity was observed exclusively in mothers of children of ASD towards several peptides, including the LDH-B peptides DCIIIVVSNPVDILT (9.1% ASD vs. 0% TD; odds ratio (95% CI) = 6.644 (0.355–124.384)) and PVAEEEATVPNNKIT (5.5% ASD vs. 0% TD; odds ratio (95% CI) = 4.067 (0.203–81.403)).These results suggest that there are differences in the binding repertoire between the antigen positive ASD and TD maternal samples. Further, the autoantibodies in plasma from mothers of children with ASD bound to a more diverse set of peptides, and there were specific peptide binding combinations observed only in this group. Future studies are underway to determine the critical amino acids necessary for autoantibody binding, which will be essential in developing a potential therapeutic strategy for maternal autoantibody related (MAR) ASD.

Objective: To assess in an observational study whether serum peptide antibody reactivities may distinguish aquaporin-4 (AQP4) antibody (Ab)–positive and -negative neuromyelitis optica spectrum disorders (NMOSD) and relapsing-remitting multiple sclerosis (RRMS). Methods: We screened 8,700 peptides that included human and viral antigens of potential relevance for inflammatory demyelinating diseases and random peptides with pooled sera from different patient groups and healthy controls to set up a customized microarray with 700 peptides. With this microarray, we tested sera from 66 patients with AQP4-Ab-positive (n = 16) and AQP4-Ab-negative (n = 19) NMOSD, RRMS (n = 11), and healthy controls (n = 20). Results: Differential peptide reactivities distinguished NMOSD subgroups from RRMS in 80% of patients. However, the 2 NMOSD subgroups were not well-discriminated, although those patients are clearly separated by their antibody reactivities against AQP4 in cell-based assays. Elevated reactivities to myelin and Epstein-Barr virus peptides were present in RRMS and to AQP4 and AQP1 peptides in AQP4-Ab-positive NMOSD. Conclusions: While AQP4-Ab-positive and -negative NMOSD subgroups are not well-discriminated by peptide antibody reactivities, our findings suggest that peptide antibody reactivities may have the potential to distinguish between both NMOSD subgroups and MS. Future studies should thus concentrate on evaluating peptide antibody reactivities for the differentiation of AQP4-Ab-negative NMOSD and MS.