No abstract

The aim of this study was to analyze the influence of oral administration of E. coli Nissle 1917 on the systemic humoral and cellular immunity in premature infants. Thirty-four premature infants were colonized with E. coli Nissle 1917 in a randomized, placebo-controlled blinded clinical trial. Stool samples of infants were analyzed repeatedly for the presence of the administered strain. The proliferative response to bacterial antigens of E. coli origin was measured in whole blood of 34 colonized infants and 27 noncolonized controls. E. coli colonization induced a significant increase in the proliferation of blood cells cultivated with bacterial components of E. coli Nissle 1917 and another E. coli strain in colonized infants as compared with noncolonized controls. Significantly higher amounts of specific anti-E. coli Nissle 1917 antibodies (Ab) of immunoglobulin (Ig)A isotype and nonspecific polyclonal IgM were found in the blood of colonized infants compared to noncolonized placebo controls. We concluded that the oral application of E. coli Nissle 1917 after birth significantly stimulates specific humoral and cellular responses and simultaneously induces nonspecific natural immunity.

Background: The development of allergies is a complex in which both composition and influence of the intestinal flora play an important role. We observed in earlier studies that the presence of an orally administered probiotic Escherichia coli strain in the intestine stimulated both a serum and local antibody response, decreased the presence of pathogens, the number of infections and the need for antibiotics. Methods: The preventive effect of oral colonization after birth with a probiotic E. coli strain was assessed by evaluating the results of a questionnaire both 20 years (150 full-term infants) and 10 years (77 preterm infants) after colonization. Results: Differences in occurrence of allergies in colonized and control subjects were statistically significant both after 10 and 20 years (p < 0.01). Specific serum IgE antibodies confirmed the presence of allergies in 100% of 10-year-old and 91% of 20-year-old patients with clinical symptoms of allergy. Ten years after colonization, the occurrence of repeated infections was significantly lower in colonized subjects than it was in controls (p < 0.01); 20 years later, no differences were found in these groups. Conclusions: Intentional colonization of the intestine with E. coli after birth (offering the advantage of the first colonizer) was found to decrease the incidence of allergies and repeated infections in later life.

The interface between the organism and the outside world, which is the site of exchange of nutrients, export of products and waste components, must be selectively permeable and at the same time, it must constitute a barrier equipped with local defense mechanisms against environmental threats (e.g. invading pathogens). The boundaries with the environment (mucosal and skin surfaces) are therefore covered with special epithelial layers which support this barrier function. The immune system, associated with mucosal surfaces covering the largest area of the body (200–300 m²), evolved mechanisms discriminating between harmless antigens and commensal microorganisms and dangerous pathogens. The innate mucosal immune system, represented by epithelial and other mucosal cells and their products, is able to recognize the conserved pathogenic patterns on microbes by pattern recognition receptors such as Toll-like receptors, CD14 and others. As documented in experimental gnotobiotic models, highly protective colonization of mucosal surfaces by commensals has an important stimulatory effect on postnatal development of immune responses, metabolic processes (e.g. nutrition) and other host activities; these local and systemic immune responses are later replaced by inhibition, i.e. by induction of mucosal (oral) tolerance. Characteristic features of mucosal immunity distinguishing it from systemic immunity are: strongly developed mechanisms of innate defense, the existence of characteristic populations of unique types of lymphocytes, colonization of the mucosal and exocrine glands by cells originating from the mucosal organized tissues (‘common mucosal system’) and preferential induction of inhibition of the responses to nondangerous antigens (mucosal tolerance). Many chronic diseases, including allergy, may occur as a result of genetically based or environmentally induced changes in mechanisms regulating mucosal immunity and tolerance; this leads to impaired mucosal barrier function, disturbed exclusion and increased penetration of microbial, food or airborne antigens into the circulation and consequently to exaggerated and generalized immune responses to mucosally occurring antigens, allergens, superantigens and mitogens.

To assess the regulatory changes of immune system in children genetically pre-disposed to allergic diseases and in their mothers, we tested cytokines IL-4, IL-5, IL-6, IL-10, IL-13, IFN-gamma and TGF-beta in 21 healthy and 21 allergic mothers (serum at the time of delivery, colostrum and milk throughout the suckling period) and their children (cord blood, venous blood and stool filtrates) up to 1 yr of age. Samples were taken at the time of delivery, 4 days post-partum and then after 3, 6 and 12 months. Significant differences between the healthy and the allergic group were found in the levels of IL-4, IL-10, IL-13 and IFN-gamma. The levels of IL-4 in the allergic group were generally higher; the levels in the sera of children of allergic mothers during the post-natal life decreased, reaching levels typical for the healthy group at 1 yr of age. Allergic mothers exhibited markedly higher IL-10 levels in the serum at the time of delivery and in milk 3 months after delivery than healthy mothers while after 6 months the IL-10 levels in all samples from the allergic group were very low. Children from allergic group had lower intestinal content of IL-13 in comparison with the healthy counterparts. At 1 yr of age, the levels of IFN-gamma in sera and stool of children from the allergic group sharply increased. TGF-beta levels in the sera of both groups were high, while in the milk they were relatively low and substantially lower that in the children's stool. TGF-beta of mammary secretions is therefore unlikely to exert a decisive regulatory influence on the children's immunity. Long-term clinical monitoring of the children will be performed to evaluate the potential prognostic significance of these changes for the future development of allergies.