B lymphocytes and B-cell activating factor promote collagen and profibrotic markers expression by dermal fibroblasts in systemic sclerosis
- Equal contributors
1 Immunorhumatologie Moléculaire, INSERM UMR_S 1109, Centre de Recherche en Immunologie et Hématologie, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, Strasbourg, France
2 Service de Rhumatologie, Centre National de Référence pour les Maladies Systémiques Autoimmunes Rares, Hôpitaux Universitaires de Strasbourg, Avenue Moliere, 67098 Strasbourg Cedex, France
Arthritis Research & Therapy 2013, 15:R168 doi:10.1186/ar4352Published: 28 October 2013
B lymphocytes might play a pathogenic role in dermal fibrosis in systemic sclerosis (SSc). B-cell activating factor (BAFF), a key cytokine for B-cell activation, is increased in the serum and the skin of patients with SSc. However, the ability of B cells directly to stimulate dermal fibroblasts and the role of BAFF are not fully understood. We therefore investigated the involvement of B cells and BAFF in the expression of collagen and profibrotic markers by dermal fibroblasts.
Cocultures of blood B cells from healthy blood donors and normal or SSc dermal fibroblasts stimulated with anti-IgM and BAFF were performed. Alpha-SMA, TIMP1, MMP9, COL1A1, COL1A2, and COL3A1 mRNA expression were determined by quantitative RT-PCR. Soluble collagen, BAFF, IL-6, IL-1β, TGF-β1, and CCL2 protein secretion were assessed.
Coculture of blood B cells and dermal fibroblasts isolated from SSc patients induced IL-6, TGF-β1, CCL2, and collagen secretion, as well as Alpha-SMA, TIMP1, and MMP9 expression in dermal fibroblasts. Transwell assays demonstrated that this induction was dependent on cell-cell contact. Addition of anti-IgM and BAFF to the coculture increased IL-6, CCL2, TGF-β1, and collagen secretion. B cell- and BAFF-induced collagen secretion was highly reduced by anti-TGF-β1 antibodies.
Our results showed for the first time a direct role of B cells on the production of collagen by dermal fibroblasts, which is further enhanced by BAFF. Thus, these results demonstrate a new pathogenic role of B cells and BAFF in fibrosis and systemic sclerosis.