Because gut microbiota has recently attracted much attention as an environmental factor involved in the development of obesity, probiotics may be useful in preventing and/or improving obesity and its related disorders. The present study aimed to investigate the effects of Lactobacillus plantarum strain No. 14 (LP14), a bacterial strain reported to decrease body fat percentage in healthy volunteers, on adipocyte size in mice. Female C57BL/6 mice were fed either normal- or high-fat diet and administered intragastrically with LP14 (1 x 10(8) colony-forming units/mouse) or vehicle daily for 11 weeks. High dietary fat intake increased body weight gain, white adipose tissue weight, mean adipocyte size and serum total cholesterol and leptin concentrations, and decreased serum adiponectin concentration. In mice fed the high-fat diet, LP14 administration significantly reduced the mean adipocyte size and tended to reduce the white adipose tissue weight and serum total cholesterol and leptin concentrations as compared with the vehicle-administered mice. All mice had undetectable serum levels of conjugated linoleic acids that reportedly exert antiobesity action. In a separate experiment, LP14 ingestion had no influence on serum triacylglycerol accumulation following olive oil administration in Triton WR1339-treated mice, suggesting that dietary fat absorption is unaffected by LP14. In conclusion, we propose that LP14 may exert a beneficial effect on the onset of diet-induced obesity by reducing the cell size of white adipose tissues, and it seems unlikely that previously reported mechanisms for other bacterial strains are involved in the action of LP14.

Excess accumulation of white adipose tissue can lead to obesity-related metabolic abnormalities such as insulin resistance. We previously reported that intragastric administration of Lactobacillus plantarum No. 14 reduced adipocyte size in diet-induced obese C57BL/6 mice. The present study tested whether L. plantarum No. 14 affects adiposity and insulin sensitivity in an animal model of type-2 diabetes mellitus. Male KK/Ta mice were fed a normal-fat diet and intragastrically given L. plantarum No. 14 (108 CFU/mouse) or vehicle daily for 10 weeks. Interscapular brown adipose tissue and inguinal, mesenteric, and retroperitoneal white adipose tissue weights, serum leptin and insulin concentrations, and insulin resistance index (HOMA-IR) were significantly lower in L. plantarum No. 14-fed mice than in vehicle-fed mice. The sum of the inguinal, epididymal, mesenteric and retroperitoneal white adipose tissue weights correlated with serum leptin and non-esterified fatty acid concentrations and HOMA-IR. The mesenteric adipose tissue mRNA levels of monocyte chemoattractant protein-1 and tumor necrosis factor-α were significantly lower in L. plantarum No. 14-fed mice than in vehicle-fed mice. Mesenteric adipose tissue weight correlated with interleukin-6, monocyte chemoattractant protein-1, and tumor necrosis factor-α mRNA levels. HOMA-IR correlated with monocyte chemoattractant protein-1 and tumor necrosis factor-α mRNA levels. These data suggest that L. plantarum No. 14 prevents the development of insulin resistance, which is at least partly attributable to the prevention of obesity, in KK/Ta mice.

Summary Strategies to manipulate gut microbiota in infancy have been considered to prevent the development of allergic diseases later in life. We previously demonstrated that maternal dietary supplementation with fructo-oligosaccharide (FOS) during pregnancy and lactation modulated the composition of gut microbiota and diminished the severity of spontaneously developing atopic dermatitis-like skin lesions in the offspring of NC/Nga mice. The present study tested whether dietary FOS affects contact hypersensitivity (CHS), another model for allergic skin disease, in NC/Nga mice. In experiment 1, 5-wk-old female NC/Nga mice were fed diets either with or without FOS supplementation for 3 wk and then received 2,4-dinitrofluorobenzene (DNFB) on the ear auricle 5 times at 7-d intervals. FOS supplementation reduced CHS response as demonstrated by ear swelling. Quantitative RT-PCR analysis showed that mRNA levels for interleukin (IL)-10, IL-12p40, and IL-17 in the lesional ear skin were significantly lower in mice fed FOS. In experiment 2, female NC/Nga mice were fed diets either with or without FOS during pregnancy and lactation. After weaning, offspring were fed the diets supplemented with or without FOS. Three weeks after weaning, offspring received DNFB on the ear auricle 4 times at 7-d intervals. Although FOS supplementation after weaning reduced ear swelling, maternal FOS consumption was ineffective in offspring. The present data suggest that dietary FOS reduces CHS while maternal FOS consumption is ineffective in offspring of DNFB-treated NC/Nga mice. Key Words fructo-oligosaccharide, 2,4-dinitrofluorobenzene, contact hypersensitivity, gut microbiota, NC/Nga mice Because gut microbiota early in life profoundly influences later immune responses ( 1-4 ), strategies to manipulate the microbiota in infancy have been considered in preventing the onset of allergic diseases. In fact, clinical trials showed that maternal administration of Lactobacillus rhamnosus GG (i.e., probiotics) during pregnancy and lactation was beneficial in preventing the development of atopic dermatitis (AD) in at-risk children during the first 4 y of life ( 5 , 6 ). Likewise, animal experiments showed that dietary supplementation with heat-killed L. rhamnosus GG in NC/Nga mice during pregnancy and lactation suppressed the spontaneous development of AD-like skin lesions in offspring ( 7 ). In addition, administration of L. rhamnosus GG in female BALB/c mice during pregnancy and lactation suppressed the ovalbumin-induced allergic airway inflammation in their offspring ( 8 ). Furthermore, administration of Lactobacillus johnsonii NCC533 in NC/Nga mice around the weaning period (i.e., 20 to 22 d of age) prevented the development of allergic skin lesions induced by topical application of mite antigen from 6 wk of age ( 9 , 10 ).Because indigestible oligosaccharides (i.e., prebiotics) modulate the composition of gut microbiota, administration of indigestible oligosaccharides during infancy could be also expected to be effective in preventing the devel...