Alteration of Immunoregulatory Patterns and Survival Advantage of Key Cell Types in Food Allergic Children.

All allergic responses to food indicate the failure of immunological tolerance, but it is unclear why cow's milk and egg (CME) allergies resolve more readily than reactivity to peanuts (PN). We sought to identify differences between PN and CME allergies through constitutive immune status and responses to cognate and non-cognate food antigens. Children with confirmed allergy to CME (n = 6) and PN (n = 18) and non-allergic (NA) (n = 8) controls were studied. Constitutive secretion of cytokines was tested in plasma and unstimulated mononuclear cell (PBMNC) cultures. Blood dendritic cell (DC) subsets were analyzed alongside changes in phenotypes and soluble molecules in allergen-stimulated MNC cultures with or without cytokine neutralization. We observed that in allergic children, constitutively high plasma levels IL-1ß, IL-2, IL-4, IL-5 and IL-10 but less IL-12p70 than in non-allergic children was accompanied by the spontaneous secretion of sCD23, IL-1ß, IL-2, IL-4, IL-5, IL-10, IL-12p70, IFN-γ and TNF-α in MNC cultures. Furthermore, blood DC subset counts differed in food allergy. Antigen-presenting cell phenotypic abnormalities were accompanied by higher B and T cell percentages with more Bcl-2 within CD69+ subsets. Cells were generally refractory to antigenic stimulation in vitro, but IL-4 neutralization led to CD152 downregulation by CD4+ T cells from PN allergic children responding to PN allergens. Canonical discriminant analyses segregated non-allergic and allergic children by their cytokine secretion patterns, revealing differences and areas of overlap between PN and CME allergies. Despite an absence of recent allergen exposure, indication of in vivo activation, in vitro responses independent of challenging antigen and the presence of unusual costimulatory molecules suggest dysregulated immunity in food allergy. Most importantly, higher Bcl-2 content within key effector cells implies survival advantage with the potential to mount abnormal responses that may give rise to the manifestations of allergy. Here, we put forward the hypothesis that the lack of apoptosis of key immune cell types might be central to the development of food allergic reactions.

Salmonella induces flagellin- and MyD88-dependent migration of bacteria-capturing dendritic cells into the gut lumen.

BACKGROUND & AIMS: Intestinal dendritic cells (DCs) sample bacteria, such as Salmonella, by extending cellular processes into the lumen to capture bacteria and shuttle them across the epithelium; however, direct evidence of bacteria-loaded DCs travelling back into the tissue is lacking. We hypothesized that sampling is paralleled by migration of DCs into the lumen prior to or following the internalization of Salmonella. METHODS: The small intestine and the colon of BALB/c and C57BL/6 mice were challenged with noninvasive Salmonella enterica serovar Typhimurium SL1344-DeltaSalmonella pathogenicity island (SPI) 1 or Escherichia coli DH5alpha by using isolated loops or oral administration by gavage. Transepithelial migration of DCs was documented by immunohistochemistry, microscopy, and flow cytometry. The role of flagellin was determined by using flagellin (DeltafliC DeltafljB)- and SPI1-SPI2 (DeltaSPI1 DeltassrA)-deficient Salmonella, flagellated E coli K12, and MyD88 mice. RESULTS: Salmonella DeltaSPI1 induced migration of CD11c(+)CX(3)CR1(+)MHCII(+)CD11b(-)CD8alpha(-) DCs into the small intestine, whereas flagellin- and SPI1-SPI2-deficient Salmonella, soluble flagellin, and E coli DH5alpha or flagellated K12, failed to do so. DC migration did not occur in the colon; it was not observed in MyD88 mice, and intraluminal DCs internalized Salmonella but did not cross the epithelium to return into tissues. Finally, DC migration was not linked to Salmonella-induced damage of the epithelium. CONCLUSIONS: DC-mediated sampling of Salmonella is accompanied by flagellin- and MyD88-dependent migration of Salmonella-capturing DCs into the intestinal lumen. We suggest that the rapid intraluminal migration of Salmonella-capturing DCs may play a role in the protection of the intestinal mucosa against bacterial infection.

UK food standards agency workshop report: diet and immune function.

The UK Food Standards Agency convened a workshop on 13 May 2009 to discuss recently completed research on diet and immune function. The objective of the workshop was to review this research and to establish priorities for future research. Several of the trials presented at the workshop showed some effect of nutritional interventions (e.g. vitamin D, Zn, Se) on immune parameters. One trial found that increased fruit and vegetable intake may improve the antibody response to pneumococcal vaccination in older people. The workshop highlighted the need to further clarify the potential public health relevance of observed nutrition-related changes in immune function, e.g. susceptibility to infections and infectious morbidity.

One-Year Consumption of a Mediterranean-Like Dietary Pattern With Vitamin D3 Supplements Induced Small Scale but Extensive Changes of Immune Cell Phenotype, Co-receptor Expression and Innate Immune Responses in Healthy Elderly Subjects: Results From the United Kingdom Arm of the NU-AGE Trial.

Amongst the major features of aging are chronic low grade inflammation and a decline in immune function. The Mediterranean diet (MedDiet) is considered to be a valuable tool to improve health status, and although beneficial effects have been reported, to date, immunological outcomes have not been extensively studied. We aimed to test the hypothesis that 1 year of a tailored intervention based on the MedDiet with vitamin D (10 µg/day) would improve innate immune responses in healthy elderly subjects (65-79 years) from the English cohort (272 subjects recruited) of the NU-AGE randomized, controlled study (clinicaltrials.gov, NCT01754012). Of the 272 subjects forming the United Kingdom cohort a subgroup of 122 subjects (61 in the intervention group and 61 in the control group) was used to evaluate ex vivo innate immune response, phenotype of circulating immune cells, and levels of pro- and anti-inflammatory markers. Odds Ratio (OR) was calculated for all the parameters analyzed. After adjustment by gender, MedDiet-females with a BMI < 31 kg/m2 had a significant upregulation of circulating CD40+CD86+ cells (OR 3.44, 95% CI 1.01-11.75, P = 0.0437). Furthermore, in all MedDiet subjects, regardless of gender, we observed a MedDiet-dependent changes, although not statistically significant of immune-critical parameters including T cell degranulation, cytokine production and co-receptor expression. Overall, our study showed that adherence to an individually tailored Mediterranean-like dietary pattern with a daily low dose of vitamin D3 supplements for 1 year modified a large variety of parameters of immune function in healthy, elderly subjects. We interpreted these data as showing that the MedDiet in later life could improve aspects of innate immunity and thus it could aid the design of strategies to counteract age-associated disturbances. Clinical Trial Registration: clinicaltrials.gov, NCT01754012.

Morphological and Functional Characterization of IL-12Rß2 Chain on Intestinal Epithelial Cells: Implications for Local and Systemic Immunoregulation.

Interaction between intestinal epithelial cells (IECs) and the underlying immune systems is critical for maintaining intestinal immune homeostasis and mounting appropriate immune responses. We have previously showed that the T helper type 1 (TH1) cytokine IL-12 plays a key role in the delicate immunological balance in the gut and the lack of appropriate levels of IL-12 had important consequences for health and disease, particularly with regard to food allergy. Here, we sought to understand the role of IL-12 in the regulation of lymphoepithelial cross talk and how this interaction affects immune responses locally and systemically. Using a combination of microscopy and flow cytometry techniques we observed that freshly isolated IECs expressed an incomplete, yet functional IL-12 receptor (IL-12R) formed solely by the IL-12Rß2 chain that albeit the lack of the complementary IL-12ß1 chain responded to ex vivo challenge with IL-12. Furthermore, the expression of IL-12Rß2 on IECs is strategically located at the interface between epithelial and immune cells of the lamina propria and using in vitro coculture models and primary intestinal organoids we showed that immune-derived signals were required for the expression of IL-12Rß2 on IECs. The biological relevance of the IEC-associated IL-12Rß2 was assessed in vivo in a mouse model of food allergy characterized by allergy-associated diminished intestinal levels of IL-12 and in chimeric mice that lack the IL-12Rß2 chain on IECs. These experimental models enabled us to show that the antiallergic properties of orally delivered recombinant Lactococcus lactis secreting bioactive IL-12 (rLc-IL12) were reduced in mice lacking the IL-12ß2 chain on IECs. Finally, we observed that the oral delivery of IL-12 was accompanied by the downregulation of the production of the IEC-derived proallergic cytokine thymic stromal lymphopoietin (TSLP). However, further analysis of intestinal levels of TSLP in IL-12Rß2-/- mice suggested that this event was not directly linked to the IEC-associated IL-12Rß2 chain. We interpreted these data as showing that IEC-associated IL12Rß2 is a component of the cytokine network operating at the interface between the intestinal epithelium and immune system that plays a role in immune regulation.

Age-Associated Decline in Dendritic Cell Function and the Impact of Mediterranean Diet Intervention in Elderly Subjects.

INTRODUCTION: Aging is accompanied by increased susceptibility to infection and age-associated chronic diseases. It is also associated with reduced vaccine responses, which is often attributed to immunosenescence and the functional decline of the immune system. Immunosenescence is characterized by a chronic, low-grade, inflammatory state termed inflammaging. Habitants of Mediterranean (MED) regions maintain good health into old age; often attributed to MED diets. HYPOTHESIS: Adoption of a MED-diet by elderly subjects, in Norfolk (UK), may improve immune responses of these individuals and in particular, dendritic cell (DC) function. EXPERIMENTAL APPROACH: A total of 120 elderly subjects (65-79 years old) recruited onto the Nu-AGE study, a multicenter European dietary study specifically addressing the needs of the elderly, across five countries, and were randomized to the control or MED-diet groups, for one year. Blood samples were taken pre- and post-intervention for DC analysis and were compared with each other, and to samples obtained from 45 young (18-40 years old) subjects. MED-diet compliance was assessed using high performance liquid chromatography-with tandem mass spectrometry analysis of urine samples. Immune cell and DC subset numbers and concentrations of secreted proteins were determined by flow cytometric analysis. RESULTS: As expected, reduced myeloid DC numbers were observed in blood samples from elderly subjects compared with young. The elevated secretion of the adipokine, resistin, after ex vivo stimulation of peripheral blood mononuclear cells from elderly subjects, was significantly reduced after MED-diet intervention. CONCLUSION: This study provides further evidence of numerical and functional effects of aging on DCs. The MED-diet showed potential to impact on the aging immune cells investigated and could provide an economical approach to address problems associated with our aging population.

Selenium supplementation has beneficial and detrimental effects on immunity to influenza vaccine in older adults.

BACKGROUND & AIMS: Mortality resulting from influenza (flu) virus infections occurs primarily in the elderly through declining immunity. Studies in mice have suggested beneficial effects of selenium (Se) supplementation on immunity to flu but similar evidence is lacking in humans. A dietary intervention study was therefore designed to test the effects of Se-supplementation on a variety of parameters of anti-flu immunity in healthy subjects aged 50-64 years. METHODS: A 12-week randomized, double-blinded, placebo-controlled clinical trial (ClinicalTrials.govNCT00279812) was undertaken in six groups of individuals with plasma Se levels <110 ng/mL. Four groups were given daily capsules of yeast enriched with 0 µg Se/day (SeY-0/d; n = 20), 50 µg Se/d (SeY-50/d; n = 18), 100 µg Se/d (SeY-100/d; n = 21) or 200 µg Se/d (SeY-200/d; n = 23). Two groups were given onion-containing meals with either <1 µg Se/d (SeO-0/d; n = 17) or 50 µg Se/d (SeO-50/d; n = 18). Flu vaccine was administrated at week 10 and immune parameters were assessed until week 12. RESULTS: Primary study endpoints were changes in cellular and humoral immune responses. Supplementation with SeY and SeO affected different aspects of cellular immunity. SeY increased Tctx-ADCC cell counts in blood (214%, SeY-100/d) before flu vaccination and a dose-dependent increase in T cell proliferation (500%, SeY-50/100/200/d), IL-8 (169%, SeY-100/d) and IL-10 (317%, SeY-200/d) secretion after in vivo flu challenge. Positive effects were contrasted by lower granzyme B content of CD8 cells (55%, SeY-200/d). SeO (Se 50 µg/d) also enhanced T cell proliferation after vaccination (650%), IFN-γ (289%), and IL-8 secretion (139%), granzyme (209%) and perforin (190%) content of CD8 cells but inhibited TNF-α synthesis (42%). Onion on its own reduced the number of NKT cells in blood (38%). These effects were determined by comparison to group-specific baseline yeast or onion control groups. Mucosal flu-specific antibody responses were unaffected by Se-supplementation. CONCLUSION: Se-supplementation in healthy human adults with marginal Se status resulted in both beneficial and detrimental effects on cellular immunity to flu that was affected by the form of Se, supplemental dose and delivery matrix. These observations call for a thorough evaluation of the risks and benefits associated with Se-supplementation.

Increased expression of a scavenger receptor (CD36) in monocytes from subjects with Type 2 diabetes.

Uptake of modified low density lipoprotein (LDL) by monocyte-macrophages is mediated by the scavenger receptor CD36, which is upregulated in vitro by high glucose concentrations and oxidatively modified LDL. We hypothesised that monocyte CD36 expression would be higher in Type 2 diabetes, and would increase during acute hyperglycaemia. Sixteen subjects with Type 2 diabetes and 11 controls underwent a 75 g oral glucose load. Monocyte CD36 expression (by laser flow cytometry), plasma LDL diene conjugates, plasma LDL hydroxyoctadecadienoic acid-13 (a peroxisome proliferator activator receptor gamma agonist) were measured at 0, 2 and 4 h. Mean monocyte CD36 expression at baseline was 34% higher in the diabetes group (P=0.01), did not change during acute hyperglycaemia and plasma LDL conjugated diene concentration was the only variable directly related to CD36 expression (F=4.53; P=0.05; r=0.51). Higher baseline CD36 expression in Type 2 diabetes could reflect increased post-transcriptional efficiency of CD36 mRNA in response to chronic hyperglycaemia and could be a proatherogenic mechanism in Type 2 diabetes.

Significant presence of terminally differentiated T cells and altered NF-kappaB and I-kappaBalpha interactions in healthy ageing.

The risk of infection and cancer increases dramatically beyond middle age, when T-cell function is noticeably altered. Nevertheless, many elderly people remain in apparently good health. To identify immunological adaptations favouring longevity, a pilot study was undertaken to compare peripheral blood T cells from healthy volunteers aged 18-25 years with those >65 years. Instead of preserved immune function in the elderly, there was an emergence of haematopoietic space particularly affecting T- and B-cell numbers, together with early signs of immunoglobulin dysregulation. Age-associated proliferative defects were present irrespective of the stimuli used. A higher constitutive expression of NF-kappaB and I-kappaBalpha in the nuclei of peripheral lymphocytes from the elderly remained unaltered by activation stimuli, despite the presence of exogenous cytokines. Nevertheless, activation resulted in their higher CD95 upregulation and more intracellular bcl-2 (suggesting a survival advantage), but lower CD27, CD28 and CD45Rb expression. The presence of CD45RO(+) CD45Rb(-) populations was unique to the elderly and their lower replicative potential was not due to the presence of CD25(+) regulatory T cells. These data collectively suggest altered gene regulation and the accumulation of terminally differentiated T cells during healthy ageing.

Nutrition, diet and immunosenescence.

Ageing is characterized by immunosenescence and the progressive decline in immunity in association with an increased frequency of infections and chronic disease. This complex process affects both the innate and adaptive immune systems with a progressive decline in most immune cell populations and defects in activation resulting in loss of function. Although host genetics and environmental factors, such as stress, exercise and diet can impact on the onset or course of immunosenescence, the mechanisms involved are largely unknown. This review focusses on identifying the most significant aspects of immunosenescence and on the evidence that nutritional intervention might delay this process, and consequently improve the quality of life of the elderly.

Oral delivery of a probiotic induced changes at the nasal mucosa of seasonal allergic rhinitis subjects after local allergen challenge: a randomised clinical trial.

OBJECTIVE: To determine effects of probiotic consumption on clinical and immunological parameters of seasonal allergic rhinitis (SAR) in an out-of-season single nasal allergen challenge. METHODS: In a study registered at ClinicalTrials.Gov (NCT01123252), a 16-week dietary intervention was undertaken in 60 patients with allergic rhinitis (>16 years old). Using a double-blinded, placebo-controlled anonymised design, the patients were divided equally into two groups. One group was given a dairy drink containing Lactobacillus casei Shirota to ingest daily while the other consumed a similar drink without bacteria. Participants attended the clinic on two consecutive days before the intervention and then again at the end of the study period. On the first day of each 2-day visit, following clinical examination, assessments were made of total nasal symptoms scores and peak nasal inspiratory flow. Nasal scrapings, nasal lavage and blood were collected for laboratory analyses of cellular phenotypes, soluble mediator release and in vitro responses to pollen allergen. These procedures were repeated 24 hours following nasal allergen challenge. RESULTS: Prior to and following intervention there were no detectable differences between study groups in measured clinical outcome. After intervention, there were differences between groups in their percentages of CD86+ epithelial cells (p = 0.0148), CD86+CD252+ non-epithelial cells (p = 0.0347), sIL-1RII release (p = 0.0289) and IL-1ß (p = 0.0224) levels at the nasal mucosa. Delivery of probiotic also suppressed production of sCD23 (p = 0.0081), TGF-ß (p = 0.0283) and induced increased production of IFN-γ (p = 0.0351) in supernatants of cultured peripheral blood. CONCLUSIONS & CLINICAL RELEVANCE: This study did not show significant probiotic-associated changes with respect to the primary clinical endpoint. An absence of overt clinical benefit may be due to an inability of single nasal challenges to accurately represent natural allergen exposure. Nevertheless, oral delivery of probiotics produced changes of the immunological microenvironment at the nasal mucosa in individuals affected by SAR. TRIAL REGISTRATION: ClinicalTrials.Gov NCT01123252.

Procyanidin effects on oesophageal adenocarcinoma cells strongly depend on flavan-3-ol degree of polymerization.

Epidemiological studies have shown that the risk of developing oesophageal adenocarcinoma (OA) is inversely correlated to consumption of fruits and vegetables. Flavan-3-ols are the most abundant subclass of flavonoids in these types of foods. Three apple-derived procyanidin fractions with different average degrees of polymerization (aDP) were characterized and the effects of these fractions and of pure flavan-3-ol monomers ((-)-epicatechin and (+)-catechin) and dimers (B1, B2) on two OA cell lines were investigated. Flavan-3-ol monomers and dimers had no effect on the two cell lines, while apple-derived flavan-3-ol oligomers and polymers induced a time-dependent reduction of cell viability. The reduction in the cell viability was due to the induction of caspase-mediated apoptosis and an arrest of the cell cycle in G0/G1. The magnitude of the reduction in cell viability and induction of apoptosis after exposure to flavan-3-ol oligomeric/polymeric fractions positively correlated with their aDP. These results indicate that only flavan-3-ol oligomers and polymers, but not monomers and dimers, have an effect on the proliferation of OA cells in vitro. As tested flavan-3-ol concentrations are achievable through diet, this study suggests that apple-derived PA may possess chemotherapeutic effects against OA.