Autoimmunity to stromal-derived autoantigens in rheumatoid ectopic germinal centers exacerbates arthritis and affects clinical response
Elisa Corsiero, … , Costantino Pitzalis, Michele Bombardieri
Elisa Corsiero, … , Costantino Pitzalis, Michele Bombardieri
Published June 17, 2024
Citation Information: J Clin Invest. 2024;134(12):e169754. https://doi.org/10.1172/JCI169754.
View: Text | PDF
Research Article Autoimmunity Article has an altmetric score of 1

Autoimmunity to stromal-derived autoantigens in rheumatoid ectopic germinal centers exacerbates arthritis and affects clinical response

Abstract

Ectopic lymphoid structures (ELSs) in the rheumatoid synovial joints sustain autoreactivity against locally expressed autoantigens. We recently identified recombinant monoclonal antibodies (RA-rmAbs) derived from single, locally differentiated rheumatoid arthritis (RA) synovial B cells, which specifically recognize fibroblast-like synoviocytes (FLSs). Here, we aimed to identify the specificity of FLS-derived autoantigens fueling local autoimmunity and the functional role of anti-FLS antibodies in promoting chronic inflammation. A subset of anti-FLS RA-rmAbs reacting with a 60 kDa band from FLS extracts demonstrated specificity for HSP60 and partial cross-reactivity to other stromal autoantigens (i.e., calreticulin/vimentin) but not to citrullinated fibrinogen. Anti-FLS RA-rmAbs, but not anti–neutrophil extracellular traps rmAbs, exhibited pathogenic properties in a mouse model of collagen-induced arthritis. In patients, anti-HSP60 antibodies were preferentially detected in RA versus osteoarthritis (OA) synovial fluid. Synovial HSPD1 and CALR gene expression analyzed using bulk RNA-Seq and GeoMx-DSP closely correlated with the lympho-myeloid RA pathotype, and HSP60 protein expression was predominantly observed around ELS. Moreover, we observed a significant reduction in synovial HSP60 gene expression followed B cell depletion with rituximab that was strongly associated with the treatment response. Overall, we report that synovial stromal-derived autoantigens are targeted by pathogenic autoantibodies and are associated with specific RA pathotypes, with potential value for patient stratification and as predictors of the response to B cell–depleting therapies.

Authors

Elisa Corsiero, Mattia Caliste, Lucas Jagemann, Liliane Fossati-Jimack, Katriona Goldmann, Cankut Cubuk, Giulia M. Ghirardi, Edoardo Prediletto, Felice Rivellese, Cristiano Alessandri, Mark Hopkinson, Behzad Javaheri, Andrew A. Pitsillides, Myles J. Lewis, Costantino Pitzalis, Michele Bombardieri

×

Figure 4

HSP60 expression in synovial tissue and SF of patients with RA.

Options: View larger image (or click on image) Download as PowerPoint
HSP60 expression in synovial tissue and SF of patients with RA. Synovium...
Synovium HSPD1 gene evaluation compared across histological pathotype in patients with early (A) and established (B) RA. Unit y axis: regularized log-normalized read. (C) Representative immunofluorescence and IHC images of synovial tissue from patients with RA showing staining for HSP60 (yellow)/CD90+ (green)/CD55+ (red) synovial fibroblasts and for CD20 (B cells), CD3 (T cells), and CD138 (plasma cells). Nuclei were stained with DAPI (blue). Original magnification, ×2 and ×10 (enlarged insets). (D) Quantification of HSP60 differential expression in RA synovial tissue (RA patients, n = 3) by QuPath analysis. Statistical analysis was done by Friedman’s test. (E) HSPD1 was differentially expressed in the lympho-myeloid (lymphoid) versus diffuse-myeloid (myeloid) pathotypes using GeoMx DSP data. (F) HSPD1 differential expression in the sublining, lining, and aggregated area using GeoMx DSP data. In E and F, statistical analysis was performed using the Mann-Whitney U test. (G) HSPD1 differential expression in the sublining and lining in diffuse-myeloid (myeloid) versus lympho-myeloid (lymphoid) pathotypes. Scatterplot shows individual regions of interest (ROIs)/. Statistical analysis was done using the Kruskal-Wallis test. (H) scRNA-Seq profiling of HSPD1 in synovial fibroblasts in leukocyte-rich/leukocyte-poor RA and OA patients (https://immunogenomics.io/ampra/). (I) Graph shows HSP60 levels (pg/mL) in matched sera and SF from patients with RA (n = 14). Statistical analysis was done with the Wilcoxon test. (J) Box plot displays SF HSP60 levels in RA (n = 20) versus OA (n = 11) patients. Statistical analysis was done using the Mann-Whitney U test. Each data point represents an individual patient. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001.