Th1 and Th17 responses to Helicobacter pylori in Bangladeshi infants, children and adults.

Both Th1 and Th17 cells are important components of the immune response to Helicobacter pylori (Hp) in adults, but less is known about T cell responses to Hp during early childhood, when the infection is often acquired. We investigated Th1 and Th17 type responses to Hp in adults, children and infants in Bangladesh, where Hp is highly endemic. IL-17 and IFN-γ mRNA levels in gastric biopsies from Hp-infected Bangladeshi adults were analyzed and compared to levels in infected and uninfected Swedish controls. Since biopsies could not be collected from infants and children, cytokine responses in Bangladeshi infants (6-12 months), children (3-5 years) and adults (>19 years) were instead compared by stimulating peripheral blood mononuclear cells (PBMCs) with a Hp membrane preparation (MP) and analyzing culture supernatants by ELISA and cytometric bead array. We found significantly higher expression of IL-17 and IFN-γ mRNA in gastric mucosa of Hp-infected Bangladeshi and Swedish adults compared to uninfected Swedish controls. PBMCs from all age groups produced IL-17 and IFN-γ after MP stimulation, but little Th2 cytokines. IL-17 and IFN-γ were primarily produced by CD4+ T cells, since CD4+ T cell depleted PBMCs produced reduced amounts of these cytokines. Infant cells produced significantly more IL-17, but similar levels of IFN-γ, compared to adult cells after MP stimulation. In contrast, polyclonal stimulation induced lower levels IL-17 and IFN-γ in infant compared to adult PBMCs and CD4+ T cells. The strong IL-17 production in infants after MP stimulation was paralleled by significantly higher production of the IL-17 promoting cytokine IL-1β from infant compared to adult PBMCs and monocytes. In conclusion, these results show that T cells can produce high levels of IL-17 and IFN-γ in response to Hp from an early age and indicate a potential role for IL-1β in promoting Th17 responses to Hp during infancy

Demographic characteristics of participants recruited to the study.

a<p>Medians (range).</p>b<p>Hp+; <i>H. pylori</i> infected, Hp-; <i>H. pylori</i> uninfected.</p

IL-17 and IFN-γ responses to <i>H. pylori</i> antigens in PBMCs.

<p>IL-17 (A) and IFN-γ (B) production from PBMCs isolated from Bangladeshi infants (n = 20), children (n = 10) and adults (n = 18) was analyzed after stimulation with <i>H. pylori</i> MP. Filled symbols represent <i>H. pylori</i> infected participants (Hp+) and open symbols <i>H. pylori</i> uninfected participants (Hp-). Responses to medium alone have been subtracted from the values shown. Horizontal lines represent median values (**<i>P</i><0.01).</p

Polyclonal cytokine responses in CD4⁺ T cells after anti-CD3/CD28 stimulation.

<p>Production of IL-17 (A), IFN-γ (B), IL-13 (C), IL-5 (D) and IL-4 (E) by CD4⁺ T cells isolated from <i>H. pylori</i> infected infants (n = 9) and adults (n = 8) was analyzed after stimulation with beads coated with anti-CD3 and anti-CD28 antibodies. Horizontal lines represent median values (*<i>P</i><0.05).</p

Zinc influences innate immune responses in children with enterotoxigenic Escherichia coli-induced diarrhea

Information is limited on the effect of zinc on immune responses in children with diarrhea due to enterotoxigenic Escherichia coli (ETEC), the most common bacterial pathogen in children. We studied the immunological effect of zinc treatment (20 mg/d) and supplementation (10 mg/d) in children with diarrhea due to ETEC. A total of 148 children aged 6-24 mo were followed up for 9 mo after a 10-d zinc treatment (ZT; n = 74) or a 10-d zinc treatment plus 3-mo supplementation (ZT+S; n = 74), as well as 50 children with ETEC-induced diarrhea that were not treated with zinc (UT). Fifty control children (HC) of the same age group from the same location were also studied. Serum zinc concentrations were higher in both the ZT (P < 0.001) and ZT+S groups (P < 0.001) than in the UT group but did not differ from the HC group. We found higher serum complement C3 immediately after zinc administration in both ZT (P < 0.001) and ZT+S (P < 0.001) groups than in the UT group. Phagocytic activity in children in both ZT (P < 0.01) and ZT+S (P < 0.01) groups was greater than in the UT group. However, oxidative burst capacity was lower in zinc-receiving groups (ZT, P < 0.001 and ZT+S, P < 0.001) than in the UT group. The naïve:memory T cell ratio in both ZT (P < 0.05) and ZT+S (P < 0.01) groups was higher than in the UT group from d 2 to 15. Increased responses, including complement C3, phagocytic activity, and changes in T cell phenotypes, suggest that zinc administration enhances innate immunity against ETEC infection in children

IL-1β production from PBMCs and monocytes in response to <i>H. pylori</i> antigens.

<p>IL-1β production from PBMCs (A) and CD14⁺ monocytes (B) isolated from <i>H. pylori</i> infected infants (n = 9) and adults (n = 7) was analysed after stimulation with <i>H. pylori</i> MP. Responses to medium alone have been subtracted from the values shown. Horizontal lines represent median values (*<i>P</i><0.05).</p

Polyclonal IL-17 and IFN-γ responses in PBMCs after PHA stimulation.

<p>IL-17 (A) and IFN-γ (B) production from PBMCs isolated from infants (n = 20), children (n = 10) and adults (n = 15) was analyzed after PHA stimulation. Filled symbols represent <i>H. pylori</i> infected participants (Hp+) and open symbols represent <i>H. pylori</i> uninfected participants (Hp-). Responses to medium alone have been subtracted from the values shown. Horizontal lines represent median values (*<i>P</i><0.05, **<i>P</i><0.01***<i>P</i><0.001).</p

Frequencies of different cell types in PBMCs isolated from infants and adults.

a<p>Frequency (%) of CD3⁺CD4⁺ cells among all cells.</p>b<p>Frequency (%) of CD45RO⁺ cells among CD3⁺CD4⁺ cells</p>c<p>Frequency (%) of CD14⁺ cells among all cells.</p><p>Values are expressed as medians (range). n = 10 for adults and n = 10 for infants.</p><p>^***P <0.001; infants versus adults.</p

Levels of different cytokines in culture supernatants after stimulation of PBMCs with <i>H. pylori</i> MP or PHA.

<p>Cytokines were measured by ELISA (IL-13, adults; n = 8 and infants; n = 9) and CBA (IL-5, IL-4, IL-10, TNF-α, IL-2; adults n = 13 and infants; n = 17). Cytokine levels (pg/ml) are expressed as medians (range) after subtraction of responses to medium alone. Lower numbers of samples could be analyzed for IL-13 than the other cytokines, since the IL-13 ELISA analysis required larger sample volumes than the CBA analysis.</p><p>***P<0.001; infants versus adults.</p

Expression of IL-17 and IFN-γ in gastric mucosa.

<p>Levels of IL-17 (A) and IFN-γ (B) mRNA were analyzed in gastric biopsy material collected from <i>H. pylori</i> infected (Hp+, filled symbols) and uninfected (Hp-, open symbols) Bangladeshi (squared symbols) and Swedish (triangular symbols) adults. The gene expression data is indicated as fold change normalized to an internal reference gene (HPRT) and relative to the calibrator sample. Horizontal lines represent median values (***<i>P</i><0.001).</p