Abstract
The ‘hygiene hypothesis’, which postulates that decreased opportunities for exposure to immunostimulating pathogens in early childhood has been proposed for the explanation of the rapidly increased prevalence of allergic diseases over the past decades. It has been suggested that association of allergy development with intestinal microflora, and probiotic bacteria have been demonstrated to be effective in the treatment of allergic disorders. Bifidobacterium longum BB536, a probiotic strain originated from a healthy infant, has been shown to be efficient in the treatment of Japanese cedar pollinosis (JCPsis)in several clinical trials. It has been reported that bifidobacteria would exhibit anti-allergic effects by modulating Th1/ Th2 balance and inducing regulatory T cells. Furthermore, in the clinical trials on JCPsis, BB536 suppressed the fluctuation along with pollen dispersion of Bacteroides fragilis group in fecal microbiota of JCPsis subjects, suggesting an indirect mechanism of BB536 by the maintenance of normal microbiota. In this review, we would introduce some data concerning the anti-allergic effects and the mechanisms of bifidobacteria with focus on the results of the efficacy of BB536 in the treatment of JCPsis.
