Culture medium from TNF-α-stimulated mesenchymal stem cells attenuates allergic conjunctivitis through multiple antiallergic mechanisms

Background The immunomodulatory and anti-inflammatory functions of mesenchymal stem cells (MSCs) have been demonstrated in several autoimmune/inflammatory diseases, but their contribution to allergic conjunctivitis and underlying antiallergic mechanisms remain elusive. Objective We sought to explore the clinical application of MSCs to experimental allergic conjunctivitis (EAC) and its underlying antiallergic mechanisms. Methods Culture medium from TNF-α-stimulated, bone marrow-derived MSCs (MSC-CMT) was administered topically to mice with EAC, and the related allergic symptoms and biological changes were evaluated. Murine spleen-derived B cells, bone marrow-derived mast cells (MCs), and lung vascular endothelial cells were cultured in vitro to investigate the antiallergic MSC-CMT mechanisms. Results Topical instillation of MSC-CMT significantly attenuated the clinical symptoms of short ragweed pollen-induced EAC, with a significant decrease in inflammatory cell frequency, nuclear factor κB p65 expression, and TNF-α and IL-4 production. In vitro MSC-CMT significantly inhibited the activation of MCs and B-cell IgE release and reduced histamine-induced vascular hyperpermeability. During EAC, MSC-CMT treatment also decreased IgE production, histamine release, enrichment and activation of MCs, and conjunctival vascular hyperpermeability. The MSC-CMT-mediated inhibition of B cells, MCs, and histamine and its antiallergic effects during EAC were abrogated when MSCs were pretreated with COX2 small interfering RNA. Conclusions Our findings provide compelling evidence that MSC-CMT inhibits EAC through COX2-dependent multiple antiallergic mechanisms and support the use of MSC-CMT as a novel strategy for treating allergic conjunctivitis.