The β2-Adrenergic Agonist Salbutamol Potentiates Oral Induction of Tolerance, Suppressing Adjuvant Arthritis and Antigen-Specific Immunity

Therapeutic protocols for treating autoimmune diseases by feeding autoantigens during the disease process have not been very successful to date. In vitro it has been shown that beta-adrenergic agonists inhibit pro-inflammatory cytokine production and up-regulate anti-inflammatory cytokine production. We hypothesized that the protective effect of oral administration of Ag would be enhanced by oral coadministration of the beta(2)-adrenergic agonist salbutamol. Here we demonstrate that oral administration of salbutamol in combination with the Ag mycobacterial 65-kDa heat shock protein increased the efficacy of disease-suppressive tolerance induction in rat adjuvant arthritis. To study the mechanism of salbutamol in more detail, we also tested oral administration of salbutamol in an OVA tolerance model in BALB/c mice. Oral coadministration of OVA/salbutamol after immunization with OVA efficiently suppressed both cellular and humoral responses to OVA. Coadministration of salbutamol was associated with an immediate increase in IL-10, TGF-beta, and IL-1R antagonist in the intestine. The tolerizing effect of salbutamol/OVA was maintained for at least 12 wk. At this time point IFN-gamma production in Ag-stimulated splenocytes was increased in the OVA/salbutamol-treated animals. In conclusion, salbutamol can be of great clinical benefit for the treatment of autoimmune diseases by promoting oral tolerance induction.