Natural antibody repertoires: development and functional role in inhibiting allergic airway disease.

In this review we discuss the effects of microbial exposure on the B cell repertoire. Neonatal exposure to conserved bacterial carbohydrates and phospholipids permanently reprograms the natural antibody repertoire directed toward these antigens by clonal expansion, alterations in clonal dominance, and increased serum antibody levels. These epitopes are present not only in bacterial cell walls, but also in common environmental allergens. Neonatal immunization with bacterial polysaccharide vaccines results in attenuated allergic airway responses to fungi-, house dust mite-, and cockroach-associated allergens in mouse models. The similarities between mouse and human natural antibody repertoires suggest that reduced microbial exposure in children may have the opposite effect, providing a potential mechanistic explanation for the hygiene hypothesis. We propose that understanding the effects of childhood infections on the natural antibody repertoire and the mechanisms of antibody-mediated immunoregulation observed in allergy models will lead to the development of prevention/interventional strategies for treatment of allergic asthma.

Transitional B cells commit to marginal zone B cell fate by Taok3-mediated surface expression of ADAM10.

Notch2 and B cell antigen receptor (BCR) signaling determine whether transitional B cells become marginal zone B (MZB) or follicular B (FoB) cells in the spleen, but it is unknown how these pathways are related. We generated Taok3-/- mice, lacking the serine/threonine kinase Taok3, and found cell-intrinsic defects in the development of MZB but not FoB cells. Type 1 transitional (T1) B cells required Taok3 to rapidly respond to ligation by the Notch ligand Delta-like 1. BCR ligation by endogenous or exogenous ligands induced the surface expression of the metalloproteinase ADAM10 on T1 B cells in a Taok3-dependent manner. T1 B cells expressing surface ADAM10 were committed to becoming MZB cells in vivo, whereas T1 B cells lacking expression of ADAM10 were not. Thus, during positive selection in the spleen, BCR signaling causes immature T1 B cells to become receptive to Notch ligands via Taok3-mediated surface expression of ADAM10.

Neonatal Exposure to Commensal-Bacteria-Derived Antigens Directs Polysaccharide-Specific B-1 B Cell Repertoire Development.

B-1 B cells derive from a developmental program distinct from that of conventional B cells, through B cell receptor (BCR)-dependent positive selection of fetally derived precursors. Here, we used direct labeling of B cells reactive with the N-acetyl-D-glucosamine (GlcNAc)-containing Lancefield group A carbohydrate of Streptococcus pyogenes to study the effects of bacterial antigens on the emergent B-1 B cell clonal repertoire. The number, phenotype, and BCR clonotypes of GlcNAc-reactive B-1 B cells were modulated by neonatal exposure to heat-killed S. pyogenes bacteria. GlcNAc-reactive B-1 clonotypes and serum antibodies were reduced in germ-free mice compared with conventionally raised mice. Colonization of germ-free mice with a conventional microbiota promoted GlcNAc-reactive B-1 B cell development and concomitantly elicited clonally related IgA+ plasma cells in the small intestine. Thus, exposure to microbial antigens in early life determines the clonality of the mature B-1 B cell repertoire and ensuing antibody responses, with implications for vaccination approaches and schedules.

Glycan-Reactive Innate-like B Cells and Developmental Checkpoints.

Using an Ig H chain conferring specificity for N-acetyl-d-glucosamine (GlcNAc), we developed transgenic (VHHGAC39 TG) mice to study the role of self-antigens in GlcNAc-reactive B-1 B cell development. In VHHGAC39 TG mice, GlcNAc-reactive B-1 B cell development during ontogeny and in adult bone marrow was normal. However, adult TG mice exhibited a block at transitional-2 immature B cell stages, resulting in impaired allelic exclusion and accumulation of a B cell subset coexpressing endogenous Ig gene rearrangements. Similarly, VHHGAC39 B cell fitness was impeded compared with non-self-reactive VHJ558 B TG cells in competitive mixed bone marrow chimeras. Nonetheless, adult VHHGAC39 mice immunized with Streptococcus pyogenes produce anti-GlcNAc Abs. Peritoneal cavity B cells transferred from VHHGAC39 TG mice into RAG-/- mice also exhibited robust expansion and anti-GlcNAc Ab production. However, chronic treatment of young VHHGAC39 mice with GlcNAc-specific mAbs leads to lower GlcNAc-binding B cell frequencies while increasing the proportion of GlcNAc-binding B1-a cells, suggesting that Ag masking or clearance of GlcNAc Ags impedes maturation of newly formed GlcNAc-reactive B cells. Finally, BCR H chain editing promotes expression of endogenous nontransgenic BCR alleles, allowing potentially self-reactive TG B cells to escape anergy or deletion at the transitional stage of precursor B cell development. Collectively, these observations indicate that GlcNAc-reactive B cell development is sensitive to the access of autologous Ags.

B-1 B Cell-Derived Natural Antibodies against N-Acetyl-d-Glucosamine Suppress Autoimmune Diabetes Pathogenesis.

Environmental factors and host microbiota strongly influence type 1 diabetes (T1D) progression. We report that neonatal immunization with group A Streptococcus suppresses T1D development in NOD mice by promoting clonal expansion of N-acetyl-d-glucosamine (GlcNAc)-specific B-1 B cells that recognize pancreatic ß cell-derived Ags bearing GlcNAc-containing posttranslational modifications. Early exposure to Lancefield group A cell-wall carbohydrate Ags increased production of GlcNAc-reactive serum Abs and enhanced localization of innate-like GlcNAc-specific B cells to pancreatic tissue during T1D pathogenesis. We show that B-1 B cell-derived GlcNAc-specific IgM engages apoptosis-associated ß cell Ags, thereby suppressing diabetogenic T cell activation. Likewise, adoptively transferring GlcNAc-reactive B-1 B cells significantly delayed T1D development in naive recipients. Collectively, these data underscore potentially protective involvement of innate-like B cells and natural Abs in T1D progression. These findings suggest that previously reported associations of reduced T1D risk after GAS infection are B cell dependent and demonstrate the potential for targeting the natural Ab repertoire in considering therapeutic strategies for T1D.

PI3 kinase signals BCR-dependent mature B cell survival.

Previous work has shown that mature B cells depend upon survival signals delivered to the cells by their antigen receptor (BCR). To identify the molecular nature of this survival signal, we have developed a genetic approach in which ablation of the BCR is combined with the activation of specific, BCR dependent signaling cascades in mature B cells in vivo. Using this system, we provide evidence that the survival of BCR deficient mature B cells can be rescued by a single signaling pathway downstream of the BCR, namely PI3K signaling, with the FOXO1 transcription factor playing a central role.

A food-exchange model for achieving the recommended dietary intakes for saturated fat in Irish children: analysis from the cross-sectional National Children's Food Survey II.

OBJECTIVE: To identify the main foods determining saturated fatty acid (SFA) intakes and model the impact of food exchanges to improve compliance with dietary fat recommendations in Irish children. DESIGN: Estimated food and nutrient intakes were obtained from a cross-sectional study, the National Children's Food Survey II. Participants were categorised into low, medium, and high SFA consumers, and the contribution of food categories to SFA intakes were compared. A food-exchange model was developed, whereby a selected range of high SFA foods were exchanged with lower SFA or unsaturated fat alternatives. SETTING: Participants were randomly selected from primary schools throughout the Republic of Ireland. PARTICIPANTS: A representative sample of 600 Irish children (5-12 years). RESULTS: The main determinants of low and high SFA consumers were milk, cheese, and butter. These foods, including snack foods, and meat and meat products, were considered exchangeable foods within the model. Compared with baseline data, modelled intakes for total fat, SFA, monounsaturated fatty acids (MUFA) and trans-fat presented decreases of 3.2, 2.7, 1.6 and <0.1% of total energy (% TE), respectively. Polyunsaturated fatty acid (PUFA), omega 6, omega 3 and alpha-linolenic acid showed increases of 1.0, 0.8, 0.2 and 0.1% TE, respectively. Compliance with total fat, MUFA and trans-fat recommendations remained adequate (100%). Adherence to SFA and PUFA recommendations improved from 18 to 63%, and 80 to 100%, respectively. CONCLUSION: The food-exchange model decreased SFA intakes and increased PUFA intakes, suggesting modest dietary changes to children's diets can effectively improve their overall dietary fat profile.

The underlying role of food guilt in adolescent food choice: A potential conceptual model for adolescent food choice negotiations under circumstances of conscious internal conflict.

Food choice decisions are challenging to conceptualise, and literature is lacking specific to adolescent food choice decisions. Understanding adolescent nutrition and food choice is becoming increasingly important. This research aims to understand what influences the food choices of Irish adolescents, and the mental negotiations occurring in food-based decisions. Additionally, it aims to develop a holistic conceptual model of food choice, specific to adolescents. A qualitative study was conducted in N = 47 Irish adolescents, via focus group discussions using vignettes to introduce discussion topics around food and eating habits. Data were analysed using reflexive thematic analysis, involving both semantic and latent analysis. Thirteen distinct factors related to adolescent food choices were discussed, forming one main theme and three inter-linking subthemes. The main theme relates to food choice being multi-factorial in nature, needing a balance of priorities through internal negotiations for food choice with the aim of reducing food guilt. This can change depending on the social setting. Social concerns and food guilt appear to play a strong role in adolescent food choice, with adolescents feeling guilty for eating unhealthy food, wasting food, or spending/wasting money on food. A conceptual model for food choice in adolescents was developed, named a "Food Choice Funnel", incorporating a specific "Food Guilt Matrix". While we should encourage healthy eating and a healthy lifestyle, it is important to understand the value placed on the social component to eating among adolescents, since they have increasing social interactions and occasions where choosing health-promoting foods may be more challenging. Healthy eating messages should be designed in a balanced manner to support healthy growth and development, while limiting the potential to induce feelings of guilt among adolescents.

Food and nutrient intakes and compliance with recommendations in school-aged children in Ireland: findings from the National Children's Food Survey II (2017-2018) and changes since 2003-2004.

The childhood years represent a period of increased nutrient requirements during which a balanced diet is important to ensure optimal growth and development. The aim of this study was to examine food and nutrient intakes and compliance with recommendations in school-aged children in Ireland and to examine changes over time. Analyses were based on two National Children's Food Surveys; NCFS (2003-2004) (n 594) and NCFS II (2017-2018) (n 600) which estimated food and nutrient intakes in nationally representative samples of children (5-12 years) using weighed food records (NCFS: 7-d; NCFS II: 4-d). This study found that nutrient intakes among school-aged children in Ireland are generally in compliance with recommendations; however, this population group have higher intakes of saturated fat, free sugars and salt, and lower intakes of dietary fibre than recommended. Furthermore, significant proportions have inadequate intakes of vitamin D, Ca, Fe and folate. Some of the key dietary changes that have occurred since the NCFS (2003-2004) include decreased intakes of sugar-sweetened beverages, fruit juice, milk and potatoes, and increased intakes of wholemeal/brown bread, high-fibre ready-to-eat breakfast cereals, porridge, pasta and whole fruit. Future strategies to address the nutrient gaps identified among this population group could include the continued promotion of healthy food choices (including education around 'healthy' lifestyles and food marketing restrictions), improvements of the food supply through reformulation (fat, sugar, salt, dietary fibre), food fortification for micronutrients of concern (voluntary or mandatory) and/or nutritional supplement recommendations (for nutrients unlikely to be sufficient from food intake alone).

Stable and metastable structures of tin (IV) oxide at high pressure.

We have analysed [Formula: see text] with a combination of synchrotron X-ray diffraction and X-ray absorption spectroscopy across a pressure range of [Formula: see text] GPa with thermal annealing by a [Formula: see text] laser allowing access to all of the known high-density polymorphs of [Formula: see text], and here report their crystallographic information. The metastability of the post-rutile [Formula: see text]-[Formula: see text] and [Formula: see text] structures in [Formula: see text] are investigated by experiment and PW-DFT simulations, revealing a complex energetic landscape and suggesting a significant dependence of the observed phases on the pressure-temperature pathway taken in experiment. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

Determining the food choice motivations of Irish teens and their association with dietary intakes, using the Food Choice Questionnaire.

During adolescence, teens start making their own food choices. While health and nutrition are important, practical and social concerns are also influential. This study aims to determine factors that motivate the food choices of Irish teens (using Food Choice Questionnaire), using data from the National Teens' Food Survey II (N = 428, 50% male, 13-18 years), and to identify how these motivations relate to dietary intakes (4-day semi-weighed food diaries). Data analysis used PCA to determine the food choice motivation subscales, and correlation and comparative statistical tests (t-test, ANOVA). Eight motivating factors were identified for Irish teens: Sensory Appeal, Price & Availability, Health & Natural Content, Familiarity, Ease of Preparation, Mood, Weight Control, and Ethical Concerns. Health and practical aspects to food choice (Price, Availability, Ease of Preparation) are important for teens, but taste (Sensory Appeal) remains a key influence. Food choice motivations vary by sex and by age, BMI status and weight perception, where girls were more motivated by health, weight control, mood and ethical concerns, and older teens were more influenced by mood and ease of preparation. Both those classified as overweight and those who perceived they were overweight were motivated more by weight control and mood for their food choices, whereas those who perceived their weight to be correct placed more importance on health and natural content. Those motivated by weight control had lower energy and higher protein intakes, and those motivated by health and natural content had more health promoting behaviours, with higher physical activity, lower screen time, and higher protein intakes. Understanding the motivations of teens' food choice can help understand why they struggle to meet dietary recommendations, and help to develop more effective health promotion messages by capitalising on the key motivations in the population.

Adequacy of calcium and vitamin D nutritional status in a nationally representative sample of Irish teenagers aged 13-18 years.

CONTEXT AND PURPOSE: In light of the key roles of vitamin D and calcium in adolescent bone health, there is a critical need for representative data on nutritional status for both micronutrients in teenagers. The present work used data from the recent representative National Teens' Food Survey II (2019-2020) to assess calcium and vitamin D intakes of teenagers in Ireland, including adequacy of such intakes, as well as, for the first time, to characterise serum 25-hydroxyvitamin D (25(OH)D) concentrations and their determinants. METHODS: Usual calcium and vitamin D intake estimates were generated using food intake data (via 4-day weighed food records) from a nationally representative sample of teenagers aged 13-18 years in Ireland (n 428). Serum 25(OH)D was measured (via LC-MS/MS) in the 57.5% (n 246) who provided a blood sample. RESULTS: Sixty-seven and 94% of Irish teenagers had intakes of calcium and vitamin D below the respective Estimated Average Requirements values, reflecting a high degree of inadequacy of intake for both micronutrients (and higher in girls than boys; P < 0.001). In addition, 21.7% and 33.1% of teenagers had serum 25(OH)D < 30 nmol/L (risk of vitamin D deficiency) and 30-49.9 nmol/L (inadequacy), respectively. Extended winter sampling, being aged 16-18 years, low total vitamin D intake, being overweight/obese or being of non-white skin type were significant (P < 0.05) predictors of serum 25(OH)D < 30 nmol/L. CONCLUSIONS: There was a high prevalence of inadequacy of intake of calcium and vitamin D in Irish teenagers, and a fifth were at increased risk of vitamin D deficiency.

Food neophobia across the life course: Pooling data from five national cross-sectional surveys in Ireland.

Food neophobia describes a reluctance to eat novel foods. Levels of food neophobia vary throughout life and are thought to peak in childhood. However, the trajectory of food neophobia across the life course is not fully clear. Using data from five national cross-sectional surveys in Ireland we explored levels of food neophobia in males and females aged 1-87 years. In addition, we assessed the influence of sociodemographic factors, breastfeeding and parental food neophobia on food neophobia. Food neophobia was measured using the Food Neophobia Scale in adults and adolescents and with the Children's Eating Behaviour Questionnaire in preschool and school aged children. A total of 3246 participants (female, 49.9%) were included. Food neophobia increased with age from 1 to ∼6 years, then decreased until early adulthood where it remained stable until increasing with age in older adults (>54 years). In adults, lower education level, social class and rural residency were associated with higher food neophobia. When preschool and school aged children surveys were pooled (ages 1-12), higher food neophobia was seen in males, children with lower parental education and those who were not breastfed. Sociodemographic factors were not significantly associated with food neophobia in adolescents. Breastfeeding duration was negatively associated with food neophobia in children and adolescents and parental food neophobia was positively associated with child's food neophobia in preschool and school aged children. The influence of socioeconomic factors was more pronounced in adults than in children or adolescents. However, sociodemographic factors only explained a small proportion of the variation in food neophobia across all ages. Longitudinal studies are needed to understand how changes in age or socioeconomic circumstance influence food neophobia at an individual level.

Food neophobia and its relationship with dietary variety and quality in Irish adults: Findings from a national cross-sectional study.

Food neophobia is characterised by a reluctance to eat novel or unfamiliar foods and has been linked to reduced dietary variety and quality. However, this link has been primarily studied in children. Therefore, we aimed to explore the relationship between food neophobia and dietary variety and quality in adults using a sub-sample of the National Adults Nutrition Survey collected between 2008 and 2010 (n = 1088). Food and nutrient intakes were assessed using a 4-day semi-weighed food diary. Food neophobia was measured using the Food Neophobia Scale (FNS). Dietary variety was assessed in three ways; Total Dietary Variety (TDV), Food-Group Variety (FGV) and Fruit and Vegetable Variety (FVV). Diet quality was assessed using the Mean Adequacy Ratio (MAR) and Nutrient-Rich Food Index (NRF9.3). A multivariate general linear model was used to assess the linear relationships between FNS score and all dietary measures, controlling for age, sex, education level, social class, location and BMI. Food neophobia was found to be inversely associated with TDV, FGV and FVV. In addition, food neophobia was negatively associated with vitamin C, magnesium and fruit and vegetable intakes and positively associated with percentage energy from free sugars. However, food neophobia was not significantly associated with all other nutrients, MAR and NRF9.3. While these results suggest food neophobia may not be a particularly important risk factor for poor nutrient status, adherence to certain dietary recommendations remains low within the Irish population and food neophobia may further inhibit the adaption of healthy and sustainable diets. Future research should seek to understand the implications of food neophobia on dietary behaviour change.

Maternal feeding practices and toddlers' fruit and vegetable consumption: results from the DIT-Coombe Hospital birth cohort in Ireland.

BACKGROUND: Health benefits of fruit and vegetable have been well recognized. However, insufficient consumption of fruit and vegetable is prevalent among toddlers, and has become a global public health issue. Maternal feeding practices are potential factors influencing toddlers' dietary intake, including fruit and vegetable intake. This study was conducted to explore the influence of maternal feeding practices on toddlers' fruit and vegetable consumption in Ireland. METHODS: A follow-up to the DIT-Coombe Hospital birth cohort was conducted. Mothers in the original cohort were invited to participate in the present follow-up study by phone. A questionnaire assessing maternal feeding behavior and the child's 3-day food diary was sent to mothers who agreed to take part in the present study by post, together with a self-addressed stamped envelope. RESULTS: There were 193 mother-children pairs included in the analysis, and the mean age of children was 2.4 (SD 0.7) years old. Toddlers' mean daily intakes of vegetable and fruit were 67.57 (SD 45.95) g and 213.35 (SD 170.78) g, respectively. Logistic regression analyses showed that maternal practice of breastfeeding for more than 4 weeks was positively associated with fruit (OR = 2.93, 95% CI: 1.29-6.64) and vegetable (OR = 1.95, 95% CI: 1.00-3.81) intake or the contribution of fruit (OR = 2.62, 95% CI: 1.19-5.80) and vegetable (OR = 2.02, 95% CI: 1.02-3.99) to the total diet. Letting the child eat with other family members was associated with high vegetable intake (OR = 5.45, 95%CI: 1.69-17.61) and high contribution of vegetable to total diet (OR = 3.78, 95% CI: 1.04-13.82). Not being too worried about the child's refusal to eat was positively associated with toddlers' vegetable intake (OR = 2.10, 95%CI: 1.09-4.05). CONCLUSIONS: To increase children's fruit and vegetable intake, and develop good eating habits, parents should eat with their toddlers, be patient and not put much pressure on their children in the context of meal feeding.

Eating behaviour styles in Irish teens: a cross-sectional study.

OBJECTIVES: To describe the eating behaviour styles of Irish teens and to explore the relationships between demographic factors, BMI and dietary intake and these eating behaviour styles. DESIGN: Cross-sectional data from the Irish National Teens' Food Survey (2005-2006). The Dutch Eating Behaviour Questionnaire assessed three eating behaviour styles in teens: restrained, emotional and external eating. Data were stratified by sex and age groups. SETTING: The Republic of Ireland. PARTICIPANTS: Nationally representative sample of teens aged 13-17 years (n 441). RESULTS: The highest scoring eating behaviour style was external eating (2·83 external v. 1·79 restraint and 1·84 emotional). Girls scored higher than boys on all three scales (Restraint: 2·04 v. 1·56, P < 0·001, Emotional: 2·15 v. 1·55, P < 0·001 and External: 2·91 v. 2·76, P = 0·03), and older teens scored higher than younger teens on the Emotional (1·97 v. 1·67, P < 0·001) and External scales (2·91 v. 2·72, P = 0·01). Teens classified as overweight/obese scored higher than those classified as normal weight on the Restraint scale (2·15 v. 1·71, P < 0·001) and lower on the External scale (2·67 v. 2·87, P < 0·03). Daily energy intake was negatively correlated with the Restraint (r -0·343, P < 0·001) and Emotional scales (r -0·137, P = 0·004) and positively correlated with the External scale (r 0·110, P = 0·02). CONCLUSIONS: External eating is the predominant eating behaviour style among Irish teens, but sex, age, BMI and dietary differences exist for each eating behaviour style. Including measures of eating behaviour styles into future dietary research could help understand both how and why as well as what people eat.

Dietary fat intakes in Irish children: changes between 2005 and 2019.

OBJECTIVE: To examine current dietary fat intakes and compliance in Irish children and to examine changes in intakes from 2005 to 2019. DESIGN: Analyses were based on data from the Irish National Children's Food Survey (NCFS) and the NSFS II, two cross-sectional studies that collected detailed food and beverage intake data through 7-day and 4-day weighed food diaries, respectively. SETTING: NCFS and NCFS II, Republic of Ireland. PARTICIPANTS: A nationally representative sample of 594 (NCFS) and 600 (NCFS II) children aged 5-12 years. Current intakes from the NCFS II were compared with those previously reported in the NCFS (www.iuna.net). RESULTS: Current intakes of total fat, SFA, MUFA, PUFA and trans fat as a percentage of total energy are 33·3, 14·0, 13·6, 5·6 and 0·5 %, respectively. Total fat, SFA and trans fat intakes since 2005 remained largely stable over time with all displaying minor decreases of <1 %. Adherence to SFA recommendations remains inadequate, with only 7 % of the population complying. Insufficient compliance with PUFA (71 %) and EPA and DHA (DHA; 16 %) recommendations was also noted. CONCLUSION: Children in Ireland continue to meet the total fat and trans fat target goals. Adherence to MUFA and PUFA recommendations has also significantly improved. However, deviations for some fats remain, in particular SFA. These findings are useful for the development of dietary strategies to improve compliance with current recommendations.

Concordance rate between copy number variants detected using either high- or medium-density single nucleotide polymorphism genotype panels and the potential of imputing copy number variants from flanking high density single nucleotide polymorphism haplotypes in cattle.

BACKGROUND: The trading of individual animal genotype information often involves only the exchange of the called genotypes and not necessarily the additional information required to effectively call structural variants. The main aim here was to determine if it is possible to impute copy number variants (CNVs) using the flanking single nucleotide polymorphism (SNP) haplotype structure in cattle. While this objective was achieved using high-density genotype panels (i.e., 713,162 SNPs), a secondary objective investigated the concordance of CNVs called with this high-density genotype panel compared to CNVs called from a medium-density panel (i.e., 45,677 SNPs in the present study). This is the first study to compare CNVs called from high-density and medium-density SNP genotypes from the same animals. High (and medium-density) genotypes were available on 991 Holstein-Friesian, 1015 Charolais, and 1394 Limousin bulls. The concordance between CNVs called from the medium-density and high-density genotypes were calculated separately for each animal. A subset of CNVs which were called from the high-density genotypes was selected for imputation. Imputation was carried out separately for each breed using a set of high-density SNPs flanking the midpoint of each CNV. A CNV was deemed to be imputed correctly when the called copy number matched the imputed copy number. RESULTS: For 97.0% of CNVs called from the high-density genotypes, the corresponding genomic position on the medium-density of the animal did not contain a called CNV. The average accuracy of imputation for CNV deletions was 0.281, with a standard deviation of 0.286. The average accuracy of imputation of the CNV normal state, i.e. the absence of a CNV, was 0.982 with a standard deviation of 0.022. Two CNV duplications were imputed in the Charolais, a single CNV duplication in the Limousins, and a single CNV duplication in the Holstein-Friesians; in all cases the CNV duplications were incorrectly imputed. CONCLUSION: The vast majority of CNVs called from the high-density genotypes were not detected using the medium-density genotypes. Furthermore, CNVs cannot be accurately predicted from flanking SNP haplotypes, at least based on the imputation algorithms routinely used in cattle, and using the SNPs currently available on the high-density genotype panel.

IL-7 Enables Antibody Responses to Bacterial Polysaccharides by Promoting B Cell Receptor Diversity.

Polysaccharide vaccines such as the Vi polysaccharide (ViPS) of Salmonella enterica serovar Typhi induce efficient Ab responses in adults but not in young children. The reasons for this difference are not understood. IL-7 dependency in B cell development increases progressively with age. IL-7Rα-mediated signals are required for the expression of many VH gene segments that are distal to DH-JH in the IgH locus and for the complete diversification of the BCR repertoire. Therefore, we hypothesized that B cells generated in the absence of IL-7 do not recognize a wide range of Ags because of a restricted BCR repertoire. Compared with adult wildtype mice, young wildtype mice and IL-7-deficient adult mice generated a significantly reduced Ab response to ViPS. Additionally, ViPS-binding B cells in adult wildtype mice predominantly used distal VH gene segments. Transgenic expression of either IL-7 or a BCR encoded by a distal VH gene segment permitted young mice to respond efficiently to bacterial polysaccharides. These results indicate that restricted VH gene usage early in life results in a paucity of Ag-specific B cell precursors, thus limiting antipolysaccharide responses.

Myeloid-Derived Suppressor Cells Impair B Cell Responses in Lung Cancer through IL-7 and STAT5.

Myeloid-derived suppressor cells (MDSCs) are known suppressors of antitumor immunity, affecting amino acid metabolism and T cell function in the tumor microenvironment. However, it is unknown whether MDSCs regulate B cell responses during tumor progression. Using a syngeneic mouse model of lung cancer, we show reduction in percentages and absolute numbers of B cell subsets including pro-, pre-, and mature B cells in the bone marrow (BM) of tumor-bearing mice. The kinetics of this impaired B cell response correlated with the progressive infiltration of MDSCs. We identified that IL-7 and downstream STAT5 signaling that play a critical role in B cell development and differentiation were also impaired during tumor progression. Global impairment of B cell function was indicated by reduced serum IgG levels. Importantly, we show that anti-Gr-1 Ab-mediated depletion of MDSCs not only rescued serum IgG and IL-7 levels but also reduced TGF-ß1, a known regulator of stromal IL-7, suggesting MDSC-mediated regulation of B cell responses. Furthermore, blockade of IL-7 resulted in reduced phosphorylation of downstream STAT5 and B cell differentiation in tumor-bearing mice and administration of TGF-ß-blocking Ab rescued these IL-7-dependent B cell responses. Adoptive transfer of BM-derived MDSCs from tumor-bearing mice into congenic recipients resulted in significant reductions of B cell subsets in the BM and in circulation. MDSCs also suppressed B cell proliferation in vitro in an arginase-dependent manner that required cell-to-cell contact. Our results indicate that tumor-infiltrating MDSCs may suppress humoral immune responses and promote tumor escape from immune surveillance.