To cite this article: Kavanagh H, Mahon BP. Allogeneic mesenchymal stem cells prevent allergic airway inflammation by inducing murine regulatory T cells. Allergy 2011; 66: 523–531.
Background: Adult bone marrow-derived mesenchymal stem cells (MSC) possess potent immune modulatory effects which support their possible use as a therapy for immune-mediated disease. MSC induce regulatory T cells (Treg) in vitro although the in vivo relevance of this is not clear.
Objective: This study addressed the hypothesis that adult bone marrow derived-MSC would prevent the pathology associated with allergen-driven airway inflammation, and sought to define the effector mechanism.
Methods: The influence of allogeneic MSC was examined in a model system where Treg induction is essential to prevent pathology. This was tested using a combination of a model of ovalbumin-driven inflammation with allogeneic MSC cell therapy.
Results: Systemic administration of allogeneic MSC protected the airways from allergen-induced pathology, reducing airway inflammation and allergen-specific IgE. MSC were not globally suppressive but induced CD4+FoxP3+ T cells and modulated cell-mediated responses at a local and systemic level, decreasing IL-4 but increasing IL-10 in bronchial fluid and from allergen re-stimulated splenocytes. Moderate dose cyclophosphamide protocols were used to differentially ablate Treg responses; under these conditions the major beneficial effect of MSC therapy was lost, suggesting induction of Treg as the key mechanism of action by MSC in this model. In spite of the elimination of Treg, a significant reduction in airway eosinophilia persisted in those treated with MSC.
Conclusion: These data demonstrate that MSC induce Tregin vivo and reduce allergen-driven pathology. Multiple Treg dependent and independent mechanisms of therapeutic action are employed by MSC.