Browsing by Author "Gasser O"

Now showing 1 - 4 of 4
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    Genetic regulation of antibody responsiveness to immunization in substrains of BALB/c mice.
    (John Wiley and Sons Inc., 2019-01-01) Poyntz HC; Jones A; Jauregui R; Young W; Gestin A; Mooney A; Lamiable O; Altermann E; Schmidt A; Gasser O; Weyrich L; Jolly CJ; Linterman MA; Gros GL; Hawkins ED; Forbes-Blom E
    Antibody-mediated immunity is highly protective against disease. The majority of current vaccines confer protection through humoral immunity, but there is high variability in responsiveness across populations. Identifying immune mechanisms that mediate low antibody responsiveness may provide potential strategies to boost vaccine efficacy. Here, we report diverse antibody responsiveness to unadjuvanted as well as adjuvanted immunization in substrains of BALB/c mice, resulting in high and low antibody response phenotypes. Furthermore, these antibody phenotypes were not affected by changes in environmental factors such as the gut microbiota composition. Antigen-specific B cells following immunization had a marked difference in capability to class switch, resulting in perturbed IgG isotype antibody production. In vitro, a B-cell intrinsic defect in the regulation of class-switch recombination was identified in mice with low IgG antibody production. Whole genome sequencing identified polymorphisms associated with the magnitude of antibody produced, and we propose candidate genes that may regulate isotype class-switching capability. This study highlights that mice sourced from different vendors can have significantly altered humoral immune response profiles, and provides a resource to interrogate genetic regulators of antibody responsiveness. Together these results further our understanding of immune heterogeneity and suggest additional research on the genetic influences of adjuvanted vaccine strategies is warranted for enhancing vaccine efficacy.
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    Impact of Mānuka Honey on Symptoms and Quality of Life in Individuals With Functional Dyspepsia: Protocol for a Feasibility Randomized Controlled Trial
    (JMIR Publications, 2025-05-21) Ombasa L; Miller J; Ware L; Abbotts-Holmes H; Tang J; Gasser O; Fraser K; Bayer S; Kemp R; Costello R; Highton A; Evans J; Merry T; Schultz M; Frampton C; Gearry R; McNabb W; Roy N; Sarvestan J
    Background: Functional dyspepsia is a common gastrointestinal condition that reduces the quality of life and increases health care costs. The lack of well-defined causes limits effective treatments. Consumers report using mānuka honey to treat gastrointestinal symptoms, although clinical evidence supporting such use is limited. Preclinical studies suggest its unique bioactive compounds may reduce gastrointestinal inflammation. Recently, 3,6,7-trimethyllumazine (Lepteridine), a natural pteridine in mānuka honey, was shown to inhibit enzymes involved in gastrointestinal inflammation in in vitro studies. Therefore, Lepteridine-standardized mānuka honey may deliver digestive health benefits. Objective: The aim of this feasibility study is to gather the data required to estimate sample size and support study logistics to design future trials. The primary objective will be preliminary assessments of the impact of Lepteridine-standardized mānuka honey on symptom severity and the quality of life in participants with mild-to-moderate functional dyspepsia. Other feasibility objectives include assessing the biological responses to mānuka honey standardized to medium and high levels of Lepteridine and measuring mānuka honey–derived metabolites in blood and urine. Methods: This is a 3-arm, parallel, controlled, double-blind, randomized feasibility study. A total of 75 healthy adults with symptoms of functional dyspepsia (Rome IV criteria) and mild-to-moderate dyspepsia severity (Short Form Leeds Dyspepsia Questionnaire) were recruited between October 2022 and September 2023. Participants were randomized into one of three groups: (1) mānuka honey standardized to contain 10 mg/kg Lepteridine, (2) mānuka honey standardized to contain 40 mg/kg Lepteridine, or (3) honey maple flavored syrup control. After a 2-week lead-in period, participants consumed 10 g of allocated intervention twice daily for 6 weeks. Throughout the study, participants completed daily bowel movement diaries and validated weekly questionnaires about their gastrointestinal symptoms and quality of life. Stool samples and 3-day diet records were collected at baseline and the end of the intervention. Blood samples were collected at baseline, weeks 2 and 4, and at the end of the intervention. In addition, 6 healthy participants without symptoms of functional dyspepsia were recruited to undergo an acute 5-hour assessment for the appearance of Lepteridine and related metabolites in plasma and urine following consumption of Lepteridine-standardized mānuka honey. The study was approved by the Northern B Health and Disability Ethics Committee. Results: Initial analysis includes 68 participants, with laboratory and data analyses being undertaken as of March 2024. The results of the primary and secondary outcomes will be published in peer-reviewed journals. Conclusions: This study will provide essential information on the potential efficacy and suitability of Lepteridine-standardized mānuka honey for designing future clinical trials investigating its effect in treating symptoms of functional dyspepsia. Trial Registration: Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12622001140741p; https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=384094 International Registered Report Identifier (IRRID): DERR1-10.2196/66417
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    "Nourish to Flourish": complementary feeding for a healthy infant gut microbiome-a non-randomised pilot feasibility study.
    (Springer Nature Limited., 2022-05-18) Lovell AL; Eriksen H; McKeen S; Mullaney J; Young W; Fraser K; Altermann E; Gasser O; Kussmann M; Roy NC; McNabb WC; Wall CR
    BACKGROUND: The introduction of complementary foods and changes in milk feeding result in modifications to gastrointestinal function. The interplay between indigestible carbohydrates, host physiology, and microbiome, and immune system development are areas of intense research relevant to early and later-life health. METHODS: This 6-month prospective non-randomised feasibility study was conducted in Auckland, New Zealand (NZ), in January 2018. Forty parents/caregivers and their infants were enrolled, with 30 infants allocated to receive a prebiotic NZ kūmara (flesh and skin; a type of sweet potato) prepared as a freeze-dried powder, and ten infants allocated to receive a commercially available probiotic control known to show relevant immune benefits (109 CFU Bifidobacterium lactis BB-12®). The primary outcome was the study feasibility measures which are reported here. RESULTS: Recruitment, participant retention, and data collection met feasibility targets. Some limitations to biological sample collection were encountered, with difficulties in obtaining sufficient plasma sample volumes for the proposed immune parameter analyses. Acceptability of the kūmara powder was met with no reported adverse events. CONCLUSION: This study indicates that recruiting infants before introducing complementary foods is feasible, with acceptable adherence to the food-based intervention. These results will inform the protocol of a full-scale randomised controlled trial (RCT) with adjustments to the collection of biological samples to examine the effect of a prebiotic food on the prevalence of respiratory tract infections during infancy. Trial registration Australia New Zealand Clinical Trials Registry ACTRN12618000157279 . Prospectively registered on 02/01/2018.
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    Nourishing the Infant Gut Microbiome to Support Immune Health: Protocol of SUN (Seeding Through Feeding) Randomized Controlled Trial.
    (JMIR Publications, 2024-09-02) Wall CR; Roy NC; Mullaney JA; McNabb WC; Gasser O; Fraser K; Altermann E; Young W; Cooney J; Lawrence R; Jiang Y; Galland BC; Fu X; Tonkie JN; Mahawar N; Lovell AL; Ma S
    Background: The introduction of complementary foods during the first year of life influences the diversity of the gut microbiome. How this diversity affects immune development and health is unclear. Objective: This study evaluates the effect of consuming kūmara or kūmara with added banana powder (resistant starch) compared to a reference control at 4 months post randomization on the prevalence of respiratory tract infections and the development of the gut microbiome. Methods: This study is a double-blind, randomized controlled trial of mothers and their 6-month-old infants (up to n=300) who have not yet started solids. Infants are randomized into one of 3 groups: control arm (C), standard kūmara intervention (K), and a kūmara intervention with added banana powder product (K+) to be consumed daily for 4 months until the infant is approximately 10 months old. Infants are matched for sex using stratified randomization. Data are collected at baseline (prior to commencing solid food) and at 2 and 4 months after commencing solid food (at around 8 and 10 months of age). Data and samples collected at each timepoint include weight and length, intervention adherence (months 2 and 4), illness and medication history, dietary intake (months 2 and 4), sleep (diary and actigraphy), maternal dietary intake, breast milk, feces (baseline and 4 months), and blood samples (baseline and 4 months). Results: The trial was approved by the Health and Disability Ethics Committee of the Ministry of Health, New Zealand (reference 20/NTA/9). Recruitment and data collection did not commence until January 2022 due to the COVID-19 pandemic. Data collection and analyses are expected to conclude in January 2024 and early 2025, respectively. Results are to be published in 2024 and 2025. Conclusions: The results of this study will help us understand how the introduction of a specific prebiotic complementary food affects the microbiota and relative abundances of the microbial species, the modulation of immune development, and infant health. It will contribute to the expanding body of research that aims to deepen our understanding of the connections between nutrition, gut microbiota, and early-life postnatal health. Trial Registration: Australian New Zealand Clinical Trials Registry ACTRN12620000026921; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378654 International Registered Report Identifier (IRRID): DERR1-10.2196/56772 JMIR Res Protoc 2024;13:e56772