Figure 3.

Fibroblast innate immune effector functions. Barrier tissue immune acting fibroblasts elicit innate immune functions required for development and homeostasis, immune activation, and immunosuppression. During steady-state conditions, fibroblasts produce cytokines and growth factors necessary for immunological priming and homeostasis (left panel). To potentially eliminate pathogens, fibroblasts release antimicrobial peptides, chemokines, and proinflammatory cytokines (middle panel). Left unchecked, this defense response could contribute to chronic inflammatory conditions. To limit excessive and protracted immune responses and prevent inflammatory disease pathogenesis, fibroblasts upregulate immune checkpoint molecules, suppressive bioactive lipid mediators, and anti-inflammatory cytokines; however, inappropriate fibroblast immunosuppression may increase risk of infection and cancer (right panel). This figure represents an amalgamation of proposed barrier tissue fibroblast innate immune effector functions. It is unclear whether each fibroblast subtype/state across tissues is capable of achieving an activation state that will enable these functions.