The effect of Lactobacillus casei on an experimental model of atopy

Abstract

The immunomodulation of IgE synthesis in the allergic process mediated by the Th1/Th2 cytokine balance is now better understood. Lactic acid bacteria (LAB) are used as microorganisms to improve health. Also well demonstrated is the effect of these bacteria as an adjuvant on the mucosal and systemic immune response. These previous reports lead us to study if some LAB, such as Lactobacillus casei strain CRL 431 which has been determined its immunopotentiator capacity, is able to modulate IgE synthesis in a mouse experimental model of allergy induced with ovalbumin. Animals were sensitized with ovalbumin by injection and aerolization. A challenge with the antigen after four weeks of IgE induction was done. L.casei was administered for 2 days at a concentration of 109 cells day-1 before sensitization, before challenge, before sensitization, and before and after challenge. In the control animal, an increase in the IgE levels, with diminution in the IFN-γ production and high level of IL-4 release was observed. In the animal treated with L.casei a down regulation of IgE synthesis by increasing of IFN-γ and diminution of IL-4 cytokines was determined. This effect was only observed when L. casei was administered before sensitization, but not before challenge. These results would indicate that the L. casei would induce Th1 activation able to increase IFN-γ cytokine with diminution of IL-4 released by Th2 lymphocytes avoiding the switch toward IgE synthesis. However, L. casei does not have an effect when Th2 are triggered and IL-4 levels are increased. The strain L. casei CRL 431 would be able to modulate Th1/Th2 cytokine balance.