Igor Splichal

Cross-talk of human gut with bifidobacteria.

The gut constitutes a prominent part of the immune system. Its commensal microflora plays an important role in defense and in tolerance to diet allergens. Disturbances in immune regulations may lead to food allergy. Among commensal bacteria, bifidobacteria are able to induce mechanisms of immune tolerance. Comprehension of their mutual cross-talk with the host is necessary for understanding their role in the diet and in food supplements.

Probiotics manipulate host cytokine response and induce antimicrobial peptides

Probiotics modulate production of both cytokine and antimicrobial peptides. This effect can be regarded as a part of complex interplay between them and the host.

Modulation of natural immunity in the gut by Escherichia coli strain Nissle 1917

The beneficial effect of probiotic Escherichia coli strain Nissle 1917 (EcN) suggests the gut epithelium plays a basic role in immune interactions with bacteria. Contrary to other commensal strains of Escherichia coli, EcN profoundly modulates the gut barrier to elevate its resistance to microbial pathogens. The present review documents the properties of EcN that have led to the protection of gnotobiotic pigs against lethal enteric infections. This effect could be important in light of the growing number of acquired deficiencies that paralyze gut immunity in humans.

Interference of Bifidobacterium choerinum or Escherichia coli Nissle 1917 with Salmonella Typhimurium in gnotobiotic piglets correlates with cytokine patterns in blood and intestine

The colonization, translocation and protective effect of two intestinal bacteria – PR4 (pig commensal strain of Bifidobacterium choerinum) or EcN (probiotic Escherichia coli strain Nissle 1917) – against subsequent infection with a virulent LT2 strain of Salmonella enterica serovar Typhimurium were studied in gnotobiotic pigs after oral association. The clinical state of experimental animals correlated with bacterial translocation and levels of inflammatory cytokines [a chemokine, interleukin (IL)‐8, a proinflammatory cytokine, tumour necrosis factor (TNF)‐α and an anti‐inflammatory cytokine, IL‐10] in plasma and intestinal lavages. Gnotobiotic pigs orally mono‐associated with either PR4 or EcN thrived, and bacteria were not found in their blood. No significant inflammatory cytokine response was observed. Mono‐association with Salmonella caused devastating septicaemia characterized by high levels of IL‐10 and TNF‐α in plasma and TNF‐α in the intestine. Di‐associated gnotobiotic pigs were given PR4 or EcN for 24 h. Subsequently, they were infected orally with Salmonella and euthanized 24 h later. Pigs associated with bifidobacteria before Salmonella infection suffered from severe systemic infection and mounted similar cytokine responses as pigs infected with Salmonella alone. In contrast, EcN interfered with translocation of Salmonella into mesenteric lymph nodes and systemic circulation. Pigs pre‐associated with EcN thrived and their clinical condition correlated with the absence of IL‐10 in their plasma and a decrease of TNF‐α in plasma and ileum.

Cytokines and other important inflammatory mediators in gestation and bacterial intraamniotic infections

Intraamniotic infections caused by viruses, bacteria or mycoplasmas are frequently followed by damage of fetus or increased perinatal morbidity and mortality. Cytokines are key substances regulating a number of biological processes including reproductive and inflammatory processes. An association between intraamniotic infections, rising concentrations of inflammatory cytokines in amniotic fluid and preterm labor is suggested. A great effort is made to find reliable markers typical for intraamniotic infections with high predictive value that make possible prompt identification of patients with intraamniotic infection. This review concerns inflammatory mediators. especially IL-1, IL-6, IL-8, TNF-α, and other important biologically active substances as prostaglandins and NO metabolites and their roles in intraamniotic infections. Finally, we discuss their relevance for diagnosis of intraamniotic df.

Growth of bifidobacteria and clostridia on human and cow milk saccharides.

For healthy infants, which were born normally and fully breastfed, the dominant component of the intestinal microflora are bifidobacteria. However, infants born by caesarean section possess clostridia as a dominant intestinal bacterial group. The aim of the present study was to determine whether bifidobacteria and clostridia are able to grow on human milk oligosaccharides (HMOs) and other carbon sources - lactose, cow milk (CM) and human milk (HM). Both bifidobacteria and clostridia grew on lactose and in CM. Bifidobacteria grew in HM and on HMOs. In contrast, 3 out of 5 strains of clostridia were not able to grow in HM. No clostridial strain was able to utilise HMOs. While both bifidobacterial strains were resistant to lysozyme, 4 out of 5 strains of clostridia were lysozyme-susceptible. It seems that HMOs together with lysozyme may act as prebiotic-bifidogenic compounds inhibiting intestinal clostridia.

Early ontogeny of immune cells and their functions in the fetal pig

The origin of immune cells and their products have been studied in the prenatal period in miniature pigs. Macrophages were first detected on day 25, and myelocytes and lymphoid cells by day 28. Membrane antigens SLA-DR and CD45 were found by day 22, membrane molecules MG-7, 8/1, CD1, CD2 and 74-22 by day 28, Gamma/delta T cells were found initially in extrathymic sites (in the liver). The first gamma/delta T cells were detected as early as 40 days of gestation. The expression of fibronectin, Thy-1 and its message, Ig isotypes and the first induction of IFN alpha were described.

Nitric Oxide Metabolites in Gnotobiotic Piglets Orally Infected with Salmonella enterica serovar Typhimurium

Reactive NO metabolites play a distinct role in the control ofSalmonella enterica serovar Typhimurium (ST; a facultative intracellular pathogen) in susceptible host. A significant increase of nitrite and/or nitrate plasma levels, 3-nitrotyrosine expression and pathological changes in mesenteric lymph nodes have been observed in gnotobiotic piglets orally infected for 1 d with a virulent strain of ST but not in piglets infected with a rough mutant of ST.

Systemic and Local Cytokine Response of Young Piglets to Oral Infection with Salmonella enterica Serotype Typhimurium

One-week-old breast-fed miniature piglets were orally infected either with virulent LT2 strain or with a non-virulent SF1591 rough mutant ofSalmonella Typhimurium for 1 d. Both micro-organisms were cultivated from mesenteric lymph nodes but not from the blood of infected piglets. Interleukins (IL) 1β, 8, 18, tumor necrosis factor α (TNF-α) and interferon γ (IFN-γ) were quantified by ELISA in plasma and washes of a terminal part of the small bowel. In plasma, cytokines were mostly missing in noninfected piglets and either missing or low in infected piglets. In the gut of non-infected piglets, IL-1β, IL-8 and IL-18 were detected whereas TNF-α and IFN-γ were mostly missing. IFN-γ levels highly increased (p < 0.05) after infection with nonvirulent salmonellae. The variability of cytokine levels in the gut of suckling piglets is discussed.

In vivo study of interferon-alpha-secreting cells in pig foetal lymphohaematopoietic organs following in utero TGEV coronavirus injection

Summary Non-infectious UV-inactivated transmissible gastroenteritis virus (TGEV) was previously shown to induce interferon alpha (IFIMα) secretion following in vitro incubation with blood mononuclear cells. In this study, pig foetuses at different stages of gestation were injected in utero with (a) partially UV-inactivated wild TGEV or (b) fully UV-inactivated wild or dm49-4 mutant TGEV Coronavirus. Nucleated cells from foetal liver, bone marrow, spleen and blood were isolated 10 or 20 h after injection and assayed ex vivo for IFNα secretion by ELISPOT and ELISA techniques. The administration of TGEV induced IFNα-secreting cells in foetal lymphohaematopoietic organs at mid-gestation. In contrast, IFNα was not detected in control sham-operated foetuses. A specific point mutation in the amino acid sequence of the viral membrane glycoprotein M of TGEV mutant dm49-4 was associated with lower or absent IFNα in utero inducibility by mutant virus as compared with wild virus. Row cytometry analysis did not show differences in leukocyte surface marker expression between control and TGEV- or between dm49-4 and wild virus-treated foetus cells, with the exception of a reduction in percentages of polymorphonuclear cells in TGEV-treated lymphohaematopoietic tissues, which is probably due to IFNα secretion. The present data provided in vivo evidence of IFNα secretion at the cell level in foetal lymphohaematopoietic organs. Such IFNα-secreting cells in lymphohaematopoietic tissues may be the source of IFNα detected during foetal infections.