Spatial Proteomic-based Phenotyping of Fibroblast Populations and their Microenvironment in Systemic Sclerosis Primary Heart Involvement

Ayla Nadja Stuetz¹, Giacomo de Luca², Alexandru-Emil Matei³, Yi-Nan Li⁴, Veronica Batani², Tim Filla⁵, Aleix Rius Rigau⁶, Bilgesu Safak Tümerdem¹, Cosimo Bruni⁷, Maike Büttner-Herold⁸, Stefania Rizzo⁹, Monica De Gaspari⁹, Markus Eckstein¹⁰, Georg Schett¹¹, Cristina Basso⁹, Jörg Distler¹², Marco Matucci-Cerinic¹³ and Andrea-Hermina Györfi¹⁴, ¹Department of Rheumatology, University Hospital Düsseldorf, Medical Faculty of Heinrich-Heine University. Hiller Research Center, University Hospital Düsseldorf, Medical Faculty of Heinrich-Heine University, Düsseldorf, Nordrhein-Westfalen, Germany, ²Vita-Salute San Raffaele University. Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS San Raffaele Hospital, Milan, Italy, ³Department of Rheumatology, University Hospital Düsseldorf, Medical Faculty of Heinrich-Heine University. Hiller Research Center, University Hospital Düsseldorf, Medical Faculty of Heinrich-Heine University. Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, and Fraunhofer Cluster of Excellence for Immune Mediated Diseases CIMD, Frankfurt am Main, Germany, Düsseldorf, Germany, ⁴University Hospital of Düsseldorf, Düsseldorf, Germany, ⁵Department of Rheumatology, University Hospital Düsseldorf, Medical Faculty of Heinrich-Heine University. Hiller Research Center, University Hospital Düsseldorf, Medical Faculty of Heinrich-Heine University., Düsseldorf, Germany, ⁶Department of Internal Medicine ³, Rheumatology and Clinical Immunology, Friedrich-Alexander-University (FAU) Erlangen-Nürnberg and Universitätsklinikum Erlangen. Deutsches Zentrum Immuntherapie (DZI), Friedrich-Alexander University (FAU) Erlangen-Nürnberg and Universitätsklinikum Erlangen, Erlangen, Germany, ⁷Department of Rheumatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland, ⁸Department of Nephropathology, University Hospital Erlangen, Erlangen, Germany, ⁹Cardiovascular Pathology Unit, Department of Cardiac, Thoracic and Vascular Sciences, University and Hospital of Padua, Padua, Italy, ¹⁰Institute of Pathology and Comprehensive Cancer Center EMN, Friedrich-Alexander- Universität (FAU) Erlangen-Nürnberg and Uniklinikum Erlangen, Erlangen, Germany, ¹¹Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany, Erlangen, Germany, ¹²University Hospital Duesseldorf and HHU, Duesseldorf, Germany, ¹³University San Raffaele Milano, Milano, Milan, Italy, ¹⁴Department of Rheumatology, University Hospital Düsseldorf, Medical Faculty of Heinrich Heine University., Düsseldorf, Germany

Meeting: ACR Convergence 2025

Keywords: Fibroblasts, Other, Heart disease, Myocarditis, proteomics, Systemic sclerosis

Session Information

Date: Tuesday, October 28, 2025

Title: (1855–1876) Systemic Sclerosis & Related Disorders – Basic Science Poster II

Session Type: Poster Session C

Session Time: 10:30AM-12:30PM

Background/Purpose: Primary heart involvement (pHI) is one of the leading causes of death in systemic sclerosis (SSc). However, the cellular and molecular pathomechanisms of SSc-pHI are largely unknown (1, 2). Compared with other forms of autoimmune or non-immune-related myocarditis associated with fibrotic remodeling, SSc-myocarditis presents a higher degree of myocardial fibrosis, which is associated with increased mortality (3). Imaging mass cytometry (IMC) is a spatial proteomic technique with cellular resolution. We aimed to characterize the fibroblast populations and their microenvironment in SSc-pHI and compare it to other forms of virus-negative, autoimmune-related myocarditis (aVNM) and isolated VNM (iVNM)) using IMC.

Methods: Endomyocardial biopsies (EMB) were obtained from the right ventricle of ten SSc-pHI-, nine iVNM, and seven aVNM patients. We designed and validated a panel of 40 metal-labeled antibodies for the identification of fibroblast populations and other types of stromal cells, as well as immune cell subsets. Data analysis was performed as described previously (4-7).

Results: We detected a total of 17985 fibroblasts and 6444 immune cells. We identified seven distinct fibroblast populations: PI16-/POSTNhigh, PI16high/POSTNhigh, FAPhigh/POSTN+, TCF21+, CD90+/ADAM12+/FSP1+, and SOX9+ fibroblasts, and myofibroblasts. We observed a significant upregulation of SOX9+ and CD90+/ADAM12+/FSP1+ fibroblasts in SSc-pHI compared with the other forms of myocarditis. PI16-/POSTNhigh and PI16high/POSTNhigh fibroblasts were associated with both SSc-pHI and aVNM. The expression of FAPhigh/POSTN+ fibroblasts was increased in aVNM and iVNM, compared with SSc-pHI. CD163high/HLA-DR+ macrophages and HLA-DRhigh monocytes were significantly upregulated in SSc-pHI compared with aVNM and iVNM. Activated helper and cytotoxic T cells and CD20+ B cells were less frequent in SSc-pHI than in aVNM. The microenvironment of PI16-/POSTNhigh fibroblasts was enriched in helper T cells and FAPhigh/POSTN+ fibroblasts, while the PI16high/POSTNhigh fibroblast niche was enriched in TCF21+ fibroblasts, CD163+/HLA-DR- macrophages, HLA-DRhigh monocytes, and CD20+ B cells. The microenvironment of SOX9+ fibroblasts was enriched in several subsets of immune cells and FAPhigh/POSTN+ fibroblasts. The SOX9+ fibroblast, CD34+ stromal cell, and pericyte niches were upregulated in SSc-pHI compared to aVNM and iVNM. We detected two myofibroblast niches, which were enriched in CD163high/HLA-DR+ macrophages, or CD90+/ADAM12+/FSP1+ fibroblasts and CD68+ mast cells, respectively. These cellular changes were associated with profound differences in the cellular interaction network of the fibroblast subsets in SSc-pHI compared to aVNM and iVNM.

Conclusion: We identify seven distinct fibroblast populations in SSc-pHI, as well as profound changes in their frequencies, their microenvironment and cellular interactions compared with other forms of myocarditis. Our findings provide new insights into the pathophysiology of SSc-pHI and may offer a rationale for specific targeting of individual fibroblast populations in cardiac fibrosis.

Disclosures: A. Stuetz: None; G. de Luca: None; A. Matei: None; Y. Li: None; V. Batani: None; T. Filla: None; A. Rius Rigau: None; B. Tümerdem: None; C. Bruni: Boehringer Ingelheim, 2, EMDO Foundation, 5, Iten-Kohaut Foundation, 5, Scleroderma Clinical Trials Consortium (SCTC), 5, Scleroderma Research Foundation (SRF), 2; M. Büttner-Herold: None; S. Rizzo: None; M. De Gaspari: None; M. Eckstein: None; G. Schett: Cabaletta, 6, Eli Lilly, 6, Janssen, 6, Kyverna, 6, Novartis, 6, UCB, 6; C. Basso: None; J. Distler: 4D Science, 8, 11, Actelion, 2, 6, Active Biotech, 2, 6, Anamar, 2, 6, Array Biopharma, 2, 6, ARXX Therapeutics, 2, 6, aTyr Pharma, 2, 6, Bayer Pharma, 2, 6, BMS (Bristol-Myers Squibb), 2, 6, Boehringer Ingelheim, 2, 6, Celgene, 2, 6, FibroCure, 4, Galapagos, 2, 6, GSK, 2, 6, Inventiva, 2, 6, JB Therapeutics, 2, 6, Medac, 2, 6, Novartis, 2, 6, Pfizer, 2, 6, Redx Pharma, 2, 6, RuiYi, 2, 6, Sanofi-Aventis, 2, 6, UCB, 2, 6; M. Matucci-Cerinic: None; A. Györfi: AbbVie, 6, Boehringer-Ingelheim, 6.

To cite this abstract in AMA style:

Stuetz A, de Luca G, Matei A, Li Y, Batani V, Filla T, Rius Rigau A, Tümerdem B, Bruni C, Büttner-Herold M, Rizzo S, De Gaspari M, Eckstein M, Schett G, Basso C, Distler J, Matucci-Cerinic M, Györfi A. Spatial Proteomic-based Phenotyping of Fibroblast Populations and their Microenvironment in Systemic Sclerosis Primary Heart Involvement [abstract]. Arthritis Rheumatol. 2025; 77 (suppl 9). https://acrabstracts.org/abstract/spatial-proteomic-based-phenotyping-of-fibroblast-populations-and-their-microenvironment-in-systemic-sclerosis-primary-heart-involvement/. Accessed .

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