The probiotic LG2055 showed lowering effects on abdominal adiposity, body weight and other measures, suggesting its beneficial influence on metabolic disorders.

Consumption of fermented milk (FM) containing a probiotic, Lactobacillus gasseri SBT2055 (LG2055), previously showed a reduction in abdominal adiposity in a randomised controlled trial (RCT) using FM with 10 8 colony-forming units (cfu) of LG2055/g. However, whether the effectiveness is observed at lower concentrations, the recommended minimum or intermediate levels of probiotics (10 6 or 10 7 cfu/g, respectively), remains to be examined. A multi-centre, double-blind, parallel-group RCT was conducted using 210 healthy Japanese adults with large visceral fat areas (80·2 -187·8 cm 2 ). They were balanced for their baseline characteristics and randomly assigned to three groups receiving FM containing 10 7 , 10 6 or 0 (control) cfu LG2055/g of FM, and were asked to consume 200 g FM/d for 12 weeks. Abdominal visceral fat areas, which were determined by computed tomography, at week 12, changed from baseline by an average of 28·5 % (95 % CI 211·9, 2 5·1; P,0·01) in the 10 7 dose group, and by 2 8·2 % (95 % CI 210·8, 2 5·7; P, 0·01) in the 10 6 dose group. Other measures including BMI, waist and hip circumferences, and body fat mass were also significantly decreased from baseline at week 12 in both groups; interestingly, the cessation of taking FM for 4 weeks attenuated these effects. In the control group, none of these parameters significantly decreased from baseline. These findings demonstrate that consumption of LG2055 at doses as low as the order of 10 8 cfu/d exhibited a significant lowering effect on abdominal adiposity, and suggest that constant consumption might be needed to maintain the effect.

LG2055 significantly prevented body weight gain, fat accumulation and pro-inflammatory gene expression in the adipose tissue. Relatively lower triglyceride levels and reduced expression of lipogenic genes were also observed in the liver. It is suggested that improvement in the inflammatory state of the adipose tissue might be a possible mechanism underlying the anti-obesity effect of LG2055.

We have demonstrated previously that a diet containing skimmed milk (SM) fermented by Lactobacillus gasseri SBT2055 (LGSP) reduces adipocyte size in Sprague -Dawley rats. Two experiments were conducted to extend these observations in order to elucidate the mechanism involved. In experiment 1, lean and obese Zucker rats were fed a diet containing SM or LGSP for 4 weeks. The LGSP diet, compared with the SM diet, resulted in lowering of the mesenteric adipose tissue weight (23 %; P,0·05), adipocyte sizes (28 %; P,0·001) and serum leptin concentration (36 %; P,0·05) in lean rats. Obese Zucker rats did not display such dietary effects. Only the number of smaller adipocytes was increased (P, 0·05) by the LGSP diet in the subcutaneous adipose tissue of obese rats. The LGSP diet significantly reduced the serum and hepatic cholesterol in rats. In addition, the LGSP diet led to an increased excretion of faecal fatty acids and total neutral faecal sterols in both rat strains. In experiment 2, Sprague -Dawley rats with permanent cannulation of the thoracic duct were fed either the SM or LGSP diets and their lymph was collected. The LGSP diet lowered the maximum transport rate of TAG and phospholipids. These results indicate that fermented milk regulates adipose tissue growth through inhibition at the stage of dietary fat absorption in lean Zucker rats.

Probiotic bacteria provide benefits in enhancing host immune responses and protecting against infection. Induction of IgA production by oral administration of probiotic bacteria in the intestine has been considered to be one reason for this beneficial effect, but the mechanisms of the effect are poorly understood. Lactobacillus gasseri SBT2055 (LG2055) is a probiotic bacterium with properties such as bile tolerance, ability to improve the intestinal environment, and it has preventive effects related to abdominal adiposity. In this study, we have found that oral administration of LG2055 induced IgA production and increased the rate of IgA+ cell population in Peyer's patch and in the lamina propria of the mouse small intestine. The LG2055 markedly increased the amount of IgA in a co-culture of B cells and bone marrow derived dendritic cells (BMDC), and TLR2 signal is critical for it. In addition, it is demonstrated that LG2055 stimulates BMDC to promote the production of TGF-β, BAFF, IL-6, and IL-10, all critical for IgA production from B cells. Combined stimulation of B cells with BAFF and LG2055 enhanced the induction of IgA production. Further, TGF-β signal was shown to be critical for LG2055-induced IgA production in the B cell and BMDC co-culture system, but TGF-β did not induce IgA production in a culture of only B cells stimulated with LG2055. Furthermore, TGF-β was critical for the production of BAFF, IL-6, IL-10, and TGF-β itself from LG2055-stimulated BMDC. These results demonstrate that TGF-β was produced by BMDC stimulated with LG2055 and it has an autocrine/paracrine function essential for BMDC to induce the production of BAFF, IL-6, and IL-10.