Anti-citrullinated protein antibodies with multiple specificities ameliorate collagen antibody-induced arthritis in a time-dependent manner.
Arthritis & rheumatology (Hoboken, N.J.)
Anti-citrullinated protein antibodies (ACPAs) are highly specific for rheumatoid arthritis (RA) and have long been regarded as pathogenic. Despite substantial in vitro evidence supporting this claim, reports investigating the pro-inflammatory effects of ACPAs in animal models of arthritis are rare and include mixed results. Here, we sequenced the plasmablast antibody repertoire of a RA patient and functionally characterized the encoded ACPAs.We expressed ACPAs from the antibody repertoire of a RA patient and characterized their autoantigen specificities on antigen arrays and ELISAs. Binding affinities were estimated by bio-layer interferometry. Select ACPAs (n=9) were tested in the collagen-antibody induced arthritis (CAIA) mouse model, to evaluate their effects on joint inflammation.Recombinant ACPAs bound preferentially, and with high affinity (nM range), to citrullinated (cit) autoantigens (primarily histones and fibrinogen), and to auto-citrullinated peptidylarginine deiminase 4 (PAD4). ACPAs were grouped for in vivo testing based on their predominant cit-antigen specificities. Unexpectedly, injections of recombinant ACPAs significantly reduced paw thickness and arthritis severity in CAIA mice, as compared to isotype-matched control antibodies (p≤0.001). Bone erosion, synovitis, and cartilage damage were also significantly reduced (p≤0.01). This amelioration of CAIA was observed for all the ACPAs tested and was independent of cit-PAD4 and cit-fibrinogen specificities. Further, disease amelioration was more prominent when ACPAs were injected at earlier stages of CAIA than at later phases of the model.Recombinant, patient-derived ACPAs ameliorated CAIA. Their anti-inflammatory effects were more preventative than therapeutic. This study highlights a potential protective role for ACPAs in arthritis.
View details for DOI 10.1002/art.42679
View details for PubMedID 37610274
Oral mucosal breaks trigger anti-citrullinated bacterial and human protein antibody responses in rheumatoid arthritis.
Science translational medicine
2023; 15 (684): eabq8476
Periodontal disease is more common in individuals with rheumatoid arthritis (RA) who have detectable anti-citrullinated protein antibodies (ACPAs), implicating oral mucosal inflammation in RA pathogenesis. Here, we performed paired analysis of human and bacterial transcriptomics in longitudinal blood samples from RA patients. We found that patients with RA and periodontal disease experienced repeated oral bacteremias associated with transcriptional signatures of ISG15+HLADRhi and CD48highS100A2pos monocytes, recently identified in inflamed RA synovia and blood of those with RA flares. The oral bacteria observed transiently in blood were broadly citrullinated in the mouth, and their in situ citrullinated epitopes were targeted by extensively somatically hypermutated ACPAs encoded by RA blood plasmablasts. Together, these results suggest that (i) periodontal disease results in repeated breaches of the oral mucosa that release citrullinated oral bacteria into circulation, which (ii) activate inflammatory monocyte subsets that are observed in inflamed RA synovia and blood of RA patients with flares and (iii) activate ACPA B cells, thereby promoting affinity maturation and epitope spreading to citrullinated human antigens.
View details for DOI 10.1126/scitranslmed.abq8476
View details for PubMedID 36812347
Rheumatoid Arthritis Patient-derived Anti-citrullinated Protein Antibodies (ACPAs) Ameliorate Joint Inflammation in Early Collagen-antibody Induced Arthritis (CAIA)
WILEY. 2022: 69-70
View details for Web of Science ID 000877386500045
Clonally Expanded B Cells in Multiple Sclerosis Bind EBV EBNA1 and GlialCAM.
Multiple sclerosis (MS) is a heterogenous autoimmune disease in which autoreactive lymphocytes attack the myelin sheath of the central nervous system (CNS). B lymphocytes in the cerebrospinal fluid (CSF) of MS patients contribute to inflammation and secrete oligoclonal immunoglobulins1,2. Epstein-Barr virus (EBV) infection has been linked to MS epidemiologically, but its pathological role remains unclear3. Here we demonstrate high-affinity molecular mimicry between the EBV transcription factor EBNA1 and the CNS protein GlialCAM, and provide structural and in-vivo functional evidence for its relevance. A cross-reactive CSF-derived antibody was initially identified by single-cell sequencing of the paired-chain B cell repertoire of MS blood and CSF, followed by protein microarray-based testing of recombinantly expressed CSF-derived antibodies against MS-associated viruses. Sequence analysis, affinity measurements, and the crystal structure of the EBNA1-peptide epitope in complex with the autoreactive Fab fragment allowed for tracking the development of the naïve EBNA1-restricted antibody to a mature EBNA1/GlialCAM cross-reactive antibody. Molecular mimicry is facilitated by a post-translational modification of GlialCAM. EBNA1 immunization exacerbates the mouse model of MS and anti-EBNA1/GlialCAM antibodies are prevalent in MS patients. Our results provide a mechanistic link for the association between MS and EBV, and could guide the development of novel MS therapies.
View details for DOI 10.1038/s41586-022-04432-7
View details for PubMedID 35073561
Characterization of Monoclonal Anti-PAD4 Autoantibodies from Rheumatoid Arthritis Patients: Functional Implications for Citrullination and Disease Progression
View details for Web of Science ID 000447268905113
Silencing of Dok-7 in Adult Rat Muscle Increases Susceptibility to Passive Transfer Myasthenia Gravis
AMERICAN JOURNAL OF PATHOLOGY
2016; 186 (10): 2559-2568
Myasthenia gravis (MG) is an autoimmune disease mediated by autoantibodies that target proteins at the neuromuscular junction, primarily the acetylcholine receptor (AChR) and the muscle-specific kinase. Because downstream of kinase 7 (Dok-7) is essential for the full activation of muscle-specific kinase and consequently for dense clustering of AChRs, we hypothesized that reduced levels of Dok-7 increase the susceptibility to passive transfer MG. To test this hypothesis, Dok-7 expression was reduced by transfecting shRNA-coding plasmids into the tibialis anterior muscle of adult rats by in vivo electroporation. Subclinical MG was subsequently induced with a low dose of anti-AChR monoclonal antibody 35. Neuromuscular transmission was significantly impaired in Dok-7-siRNA-electroporated legs compared with the contralateral control legs, which correlated with a reduction of AChR protein levels at the neuromuscular junction (approximately 25%) in Dok-7-siRNA-electroporated muscles, compared with contralateral control muscles. These results suggest that a reduced expression of Dok-7 may play a role in the susceptibility to passive transfer MG, by rendering AChR clusters less resistant to the autoantibody attack.
View details for DOI 10.1016/j.ajpath.2016.05.025
View details for Web of Science ID 000384389400007
View details for PubMedID 27658713