Colonization and immunomodulation by Lactobacillus reuteri ATCC 55730 in the human gastrointestinal tract.

Lactobacillus reuteri ATCC 55730 is a probiotic (health-promoting) bacterium widely used as a dietary supplement. This study was designed to examine local colonization of the human gastrointestinal mucosa after dietary supplementation with L. reuteri ATCC 55730 and to determine subsequent immune responses at the colonized sites. In this open clinical investigation, 10 healthy volunteers and 9 volunteers with ileostomy underwent gastroscopy or ileoscopy and biopsy samples were taken from the stomach, duodenum, or ileum before and after supplementation with 4 x 10(8) CFU of live L. reuteri ATCC 55730 lactobacilli per day for 28 days. Biopsy specimen colonization was analyzed using fluorescence in situ hybridization with a molecular beacon probe, and immune cell populations were determined by immunostaining. Endogenous L. reuteri was detected in the stomach of 1 subject and the duodenum of 3 subjects (out of 10 subjects). After L. reuteri ATCC 55730 supplementation, the stomachs of 8 and the duodenums of all 10 subjects were colonized. Three ileostomy subjects (of six tested) had endogenous L. reuteri at baseline, while all six displayed colonization after L. reuteri supplementation. Gastric mucosal histiocyte numbers were reduced and duodenal B-lymphocyte numbers were increased by L. reuteri ATCC 55730 administration. Furthermore, L. reuteri administration induced a significantly higher amount of CD4-positive T-lymphocytes in the ileal epithelium. Dietary supplementation with the probiotic L. reuteri ATCC 55730 induces significant colonization of the stomach, duodenum, and ileum of healthy humans, and this is associated with significant alterations of the immune response in the gastrointestinal mucosa. These responses may be key components of a mechanism by which L. reuteri ATCC 55730 exerts its well-documented probiotic effects in humans.

Supplementation of infant formula with the probiotic lactobacillus reuteri and zinc: impact on enteric infection and nutrition in infant rhesus monkeys.

UNLABELLED: Gut colonization by may have beneficial effects on infant health or capacity to resist infectious disease. Zinc supplementation has also been proposed to increase infants' resistance to disease; however, many studies have yielded conflicting results. OBJECTIVES: To study effects of probiotic supplementation of infant formula (with or without supplemental zinc) on nutritional status, gut colonization and the ability to resist gastrointestinal infection in an infant rhesus monkey model. METHODS: Infant monkeys were fed control infant formula (5 mg Zn/L), control formula with or control formula with and supplemental zinc (15 mg Zn/L) from birth to 4 months. Growth, nutritional status, mineral absorption, intestinal colonization and frequency and severity of enteropathogenic -induced gastroenteritis were monitored. RESULTS: Gastrointestinal colonization was achieved and was associated with increased ileal villous surface area and improved hematocrit, with no adverse effects on growth or nutritional indices. Fortification to 15 mg Zn/L reduced plasma copper, erythrocyte Cu/Zn-superoxide dismutase, hemoglobin, and iron absorption. Infants fed -supplemented formula had reduced diarrhea severity throughout the study period and recovered more rapidly from acute diarrhea than the other groups. CONCLUSION: -supplementation of infant formula is safe, improves iron status and decreases diarrhea severity in infant rhesus monkeys and thus may help protect formula-fed human infants from infection and nutritional deficiencies.