Figure 3.

Role of fibroblast functions in acute and chronic injury. a) In acute injury, tissue damage activates pathogen– and damage–related molecular patterns on macrophages and granulocytes. Cytokines subsequently released by these cells, such as TNF or OSM, and IL–1β induce a pro–inflammatory phenotype fibroblast formation. b) The local cytokine environment initiates LTo–like stromal cells in a chronic inflammatory environment. It induces the expression of chemokines such as CCL19, CCL21, CXCL12, and CXCL13. LTo–like stromal cells recruit immature CD4+ T cells, LAMP3+ DCs, and follicular B cells and eventually form a tertiary lymphoid structure. TNF, tumor necrosis factor, OSM, oncostatin M, IL, interleukin, LTo, lymphoid tissue organizer, CCL, CC–chemokine ligand, CXCL, CXC–chemokine ligand, DC, dendritic cell, FAP, fibroblast activation protein, LIF, leukemia inhibitory factor, LTβR, lymphotoxin–β receptor.