Selected commensal bacteria change profiles of Helicobacter pylori-induced T cells via dendritic cell modulation.

BACKGROUND: The mechanisms of downregulation of protective immunity against Helicobacter pylori (Hp) infection strongly depend on dendritic cell (DC)-induced T-lymphocyte differentiation pattern. Lactic acid bacteria (LAB) strains can modulate Hp-induced immunoresponse by changes in DC activation profiles. Here, we want to find out if the LAB-pulsed DCs will change Hp-induced T-cell responsiveness patterns. MATERIALS AND METHODS: The naive peripheral CD4+ T cells were co-cultured with Hp CagA + pulsed monocyte-derived DCs (DC/CD4+ T cell) in the presence/absence of the feces-derived probiotics: antagonistic or non-antagonistic to Hp (Lactobacillus rhamnosus 900, Lr, Lactobacillus paracasei 915, Lp, respectively), as assessed by the agar slab method. The regulatory T-cell (Treg) population was assessed by flow cytometry, and IFN-γ, IL-12p70, IL-10, and IL-17A levels were evaluated by ELISA method. RESULTS: The Hp-pulsed DC/CD4+ T-cell co-cultures were characterized by high IL-10, decreased IL-12p70 and IFN-γ levels, and elevated Treg population. In contrast, Lr-pulsed DC/CD4+ T-cell co-cultures expressed low IL-10, high IL-12p70 and IFN-γ levels and declined Treg population; this responsiveness pattern was not changed by Hp. The responsiveness pattern of the Lp/Hp-pulsed DC/CD4+ T-cell co-cultures did not differ from those pulsed with Hp alone. CONCLUSION: In contrast to Lp, Lr probiotic strain overcomes Hp-mediated immune profile in the DC/T-cell co-cultures toward Th1 pattern and limited generation of Tregs in vitro. Lr may therefore be used as a component of anti-Hp treatment.

Relationship between Helicobacter pylori Infection and Plasmacytoid and Myeloid Dendritic Cells in Peripheral Blood and Gastric Mucosa of Children.

PURPOSE: To investigate the frequency and activation status of peripheral plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) as well as gastric mucosa DC subset distribution in Helicobacter pylori- (H. pylori-) infected and noninfected children. MATERIALS AND METHODS: Thirty-six children were studied; twenty-one had H. pylori. The frequencies of circulating pDCs (lineage-HLA-DR+CD123+) and mDCs (lineage-HLA-DR+CD11c+) and their activation status (CD83, CD86, and HLA-DR expression) were assessed by flow cytometry. Additionally, the densities of CD11c+, CD123+, CD83+, CD86+, and LAMP3+ cells in the gastric mucosa were determined by immunohistochemistry. RESULTS: The frequency of circulating CD83+ mDCs was higher in H. pylori-infected children than in the noninfected controls. The pDCs demonstrated upregulated HLA-DR surface expression, but no change in CD86 expression. Additionally, the densities of gastric lamina propria CD11c+ cells and epithelial pDCs were increased. There was a significant association between frequency of circulating CD83+ mDCs and gastric lamina propria mDC infiltration. CONCLUSION: This study shows that although H. pylori-infected children had an increased population of mature mDCs bearing CD83 in the peripheral blood, they lack mature CD83+ mDCs in the gastric mucosa, which may promote tolerance to local antigens rather than immunity. In addition, this may reduce excessive inflammatory activity as reported for children compared to adults.

[Lactic acid bacteria and health: are probiotics safe for human?]. / Bakterie kwasu mlekowego i zdrowie: czy probiotyki sa bezpieczne dla czlowieka?

The effect of Lactobacillus and Bifidobacterium on human health has been examined for many years. Numerous in vivo and in vitro studies have confirmed the beneficial activity of some exogenous lactic acid bacteria in the treatment and prevention of rotaviral infection, antibiotic-associated diarrhea, inflammatory bowel disease and other gastrointestinal disorders. Probiotics support the action of the intestinal microflora and exhibit a favorable modulatory effect on the host's immune system. However, it should be remembered that relatively harmless lactobacilli can occasionally induce opportunistic infections. Due to reaching almost 20x10(12) probiotic doses per year which contain live cultures of bacteria, it is essential to monitor the safety aspect of their administration. In recent years, infections caused by Lactobacillus and Bifidobacterium made up 0.05% to 0.4% of cases of endocarditis and bacteremia. In most cases, the infections were caused by endogenous microflora of the host or bacterial strains colonizing the host's oral cavity. According to a review of cases of infections caused by bacteria of the genus Lactobacillus from 2005 (collected by J.P. Cannot'a), 1.7% of infections have been linked directly with intensive dairy probiotic consumption by patients. Additionally, due to the lack of a precise description of most individuals' eating habits, the possible effect of probiotics on infection development definitively should not be ruled out. The present paper describes cases of diseases caused by lactic acid bacteria, a potential mechanism for the adverse action of bacteria, and the possible hazard connected with probiotic supplementation for seriously ill and hospitalized patients.

Lactic acid bacteria strains exert immunostimulatory effect on H. pylori-induced dendritic cells.

The aim of this study was to find out if selected lactic acid bacteria (LAB) strains (antagonistic or nonantagonistic against H. pylori in vitro) would differ in their abilities to modulate the DCs maturation profiles reflected by their phenotype and cytokine expression patterns. Methods. Monocyte-derived DCs maturation was elicited by their direct exposure to the LAB strains of L. rhamnosus 900 or L. paracasei 915 (antagonistic and nonantagonistic to H. pylori, resp.), in the presence or absence of H. pylori strain cagA+. The DCs maturation profile was assessed on the basis of surface markers expression and cytokines production. Results. We observed that the LAB strains and the mixtures of LAB with H. pylori are able to induce mature DCs. At the same time, the L. paracasei 915 leads to high IL-10/IL-12p70 cytokine ratio, in contrast to L. rhamnosus 900. Conclusions. This study showed that the analyzed lactobacilli strains are more potent stimulators of DC maturation than H. pylori. Interestingly from the two chosen LAB strains the antagonistic to H. pylori-L. rhamnosus strain 900 has more proinflammatory and probably antibactericidal properties.

Phenotype of NK Cells Determined on the Basis of Selected Immunological Parameters in Children Treated due to Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is the most frequent pediatric malignancy. The chemotherapy for ALL is associated with a profound secondary immune deficiency.We evaluated the number and phenotype of natural killer (NK) cells at diagnosis, after the intensive chemotherapy and following the completion of the entire treatment for patients with ALL. The fraction, absolute number, and percentage of NK cells expressing interferon-γ were determined in full blood samples. The fraction of NK cells expressing CD158a, CD158b, perforin, A, B, and K granzymes was examined in isolated NK cells.We have shown that patients assessed at ALL diagnosis showed significantly lower values of the fraction of NK cells and percentage of NK cells with the granzyme A expression. Additionally, the absolute number of NK cells, the expression of CD158a, CD158b, perforin, and granzyme A were significantly lower in patients who completed intensive chemotherapy. Also, there was a significantly higher fraction of NK cells expressing granzyme K in patients who completed the therapy.Abnormalities of NK cells were found at all stages of the treatment; however, the most pronounced changes were found at the end of intensive chemotherapy.