Characterization of Circulating and Skin-infiltrating B Cells in Systemic Sclerosis

**CHARACTERIZATION OF CIRCULATING AND SKIN-INFILTRATING B CELLS IN SYSTEMIC SCLEROSIS**: - Réf **ABG-129122** - Sujet de Thèse - 04/03/2025 - Contrat doctoral - "université de lille" - Lieu de travail- Lille - Les Hauts de France - France - Intitulé du sujet- CHARACTERIZATION OF CIRCULATING AND SKIN-INFILTRATING B CELLS IN SYSTEMIC SCLEROSIS - Champs scientifiques- Santé, médecine humaine, vétérinaire - Biologie - Mots clés- B lymphocytes, fibrosis, systemic sclerosis **Description du sujet**: Systemic sclerosis (SSc) is an autoimmune disease characterized by inflammatory fibrosis of the skin and organs such as the lungs and heart. It is the most severe autoimmune disease, currently without a curative treatment. From a pathophysiological perspective, it is characterized by a triad of vasculopathy-immune dysregulation-fibrosis, making it a paradigmatic model for fibrotic complications observed in inflammatory diseases. As an autoimmune disease, it is now well established that B lymphocytes (BLs) play a crucial role in the pathophysiological triad of SSc. In our laboratory, we have successively demonstrated and published that: 1. BLs from patients with SSc, as well as those from experimental models of SSc, exhibit altered homeostasis and function, notably with significant activation and a decrease in regulatory BLs producing IL-10. 2. BLs from SSc patients have an increased ability to infiltrate a 3D model of healthy skin, especially when they are pre-activated (PMID: 39185406). The consequences of this infiltration include modifications in their homeostasis and function, as well as the induction of a pro - inflammatory phenotype in fibroblasts, which are key cells in fibrogenesis. The PhD project aims to: 1. Characterize circulating BLs from SSc patients and study their interactions in a co-culture model with reconstructed pathological skin, including fibroblastic cells derived from patients. 2. Modulate these interactions by blocking the involved pathways. 3. Validate one or more therapeutic targets in experimental models. Experimental Plan and Expected Results 1. Spectral cytometry analysis of circulating BLs from SSc patients: 2. Cell Culture and Bioprinting/Organ-on-Chip Models (CPER Tecsanté): - Develop a 3D skin model reflecting SSc pathology using bioprinting or Organ-on-Chip technology. - Integrate fibroblastic cells from SSc patients to simulate the disease environment. 3. Co-culture Experiments: - Cultivate BLs from SSc patients and healthy individuals with the 3D pathological skin model or Organ-on-Chip. - Assess fibroblast and BL activation using FACS, bulk RNA sequencing, and scRNA sequencing on the most relevant co-culture conditions. 4. Blocking of Signaling Pathways: - Use monoclonal antibodies or inhibitors targeting BL activation pathways identified in the co-culture model. - Identify a common pathway between BLs and fibroblasts for targeted intervention. 5. Validation in Experimental Models - Use well-established animal models within the research unit to validate identified therapeutic targets. - Utilize the tissue bank (skin samples) collected within the FHU PRECISE framework to confirm the expression of validated therapeutic targets. Publications and Collaborations Publications: - A methodological article on the pathological skin model (M18). - A thesis-related article (M33). Planned Collaborations: 1. CPER REsist-Omics (FACS and confocal microscopy). 2. CPER TecSanté (pathological skin model). 3. FHU PRECISE (PBMC and tissue biobank from SSc patients). Conclusion Ultimately, we aim to identify modifications in BLs and fibroblast homeostasis after co-culture in a pathological skin model. We seek to discover common therapeutic targets between BLs and fibroblasts and test them in experimental models of SSc. **Prise de fonction**: - 01/09/2025 **Nature du financement**: - Contrat doctoral **Précisions sur le financement**: - conditioné à la réussite au concours de l'école doctorale de juin 2025 **Présentation établissement et labo d'accueil**: - "université de lille" **Intitulé du doctorat**: - Doctorat Sciences de la vie et de la santé **Pays d'obtention du doctorat**: - France **Etablissement délivrant le doctorat**: - Université de Lille **Ecole doctorale**: - Biologie - Santé FACS Biologie moléculaire Culture cellulaire FACS, molecular biology cell culture- 30/04/2025