Recipient Organization
INDIANA UNIVERSITY
JORDAN HALL 142
BLOOMINGTON,IN 47401
Performing Department
(N/A)
Non Technical Summary
Worldwide, 18.3% of the population 50 yrs of age and older have osteoporosis, and women are four times more likely to be affected than men. The primary culprit, postmenopausal bone loss, is now recognized as an inflammatory driven process that interferes with normal bone cell activity. The decline in estrogen that occurs with menopause brings about physiological changes in the immune system which if left unchecked results in significant bone loss. Despite the development of drugs targeting the bone to treat osteoporosis, adherence to these pharmacological regimens remains poor. Studies using laboratory animals point to specialized immune cells (i.e., T cells) as the primary cell that is responsible for these negative effects on bone. A large proportion of a person's T cells can be found at any one time within the lining of the intestine. These cells can leave the intestine and travel to other parts of the body such as bone. T cells in the intestine are affected by the foods that we eat and by the microorganisms that reside within the intestine (i.e., gut microbiota). Our preliminary data show that dried plums act as prebiotics which have potent effects on the gut microbiota and alter T cell function in laboratory models of postmenopausal osteoporosis. Clinical with postmenopausal women have clearly demonstrated that supplementing the diet with dried plums prevents postmenopausal bone loss. Yet, to date no comprehensive study of the effects of dried plums on immune function in humans has been undertaken. The goal of this project is to determine the extent to which these gut-mediated, T cell responses observed in animal models translate to improving immune function in postmenopausal women. Because of this population's risk for suboptimal vitamin D status and vitamin D's effects on T cells, we will also explore how vitamin D status affects the response to dried plum. To accomplish this, we will recruit postmenopausal women to participate in a 10-week crossover study (i.e., 4 wks with and 4 wks without dried plum with 2 weeks in between). We will determine the influence of dried plums on 1) immune (T cell) function and 2) the gut microbiota and gut-derived metabolites; and (3) investigate how vitamin D status affects these responses. We anticipate that this project will provide advance our understanding of how supplementing the diet with foods that have prebiotic activity could be used to improve immune function in women. Because of the role of the immune system in many diseases that disproportionately affect women, this work could have implications that extend beyond improving bone health to other diseases (e.g., autoimmune diseases, cardiovascular disease, and certain cancers.) Furthermore, positive findings related to this study could impact growers as well as the dried plum industry more broadly.
Animal Health Component
60%
Research Effort Categories
Basic
40%
Applied
60%
Developmental
(N/A)
Goals / Objectives
Dried plums have been shown in both pre-clinical and clinical studies to have prebiotic activity.Scientific Goals: From a scientific standpoint, the goals of this project are to investigate how supplementing the diet of postmenopausal women with dried plums affects T cells and their function. Furthermore, we will explore whether vitamin D status of the host alters this response.These scientific goals will be achieved by accomplishing the following objectives:Objective 1) Determine how dried plum supplementation alters circulating T effector cell populations (i.e., T helper cells expressing IL-17 [Th17 cells] & T regulatory [T-reg] cells) and their response to an immune challenge compared to a control diet period; Objective 2) Assess the prebiotic activity of dried plums by examining changes in the gut microbiota and gut-derived metabolites in response to dried plum supplementation compared to the control diet period; Objective 3) Determine whether serum vitamin D influences the immune, metabolite and microbiota responses to dried plum; andObjective 4) Investigate the relationship of the immune, metabolite and microbiota outcomes to the bone resorption marker, c-terminal telopeptide 1 (CTX-1).By carrying out these objectives, we expect to discern whether supplementing the diet with dried plums improves immune function in postmenopausal women and the influence that vitamin D status has on this response.Training Goal: In addition to the scientific goals, this project will provide a unique training opportunity for a post-doctoral fellow who has interests in a career in translational research. Objective 1) Gain experience in conducting a clinical study. The post-doctoral fellow will be involved in all aspects of the study;Objective 2) Develop advanced laboratory skills that incorporate working with cell culture systems and fluorescence-activated cell sorting, among other technical assays; andObjective 3) Learn advanced bioinformatics techniques by working with co-PDs on "omics" data.
Project Methods
A clinical study with postmenopausal women, age 55-70 yrs (n=30) will be conducted using a randomized crossover control design. Eligible volunteers who are willing to consume 50 grams of dried plum per day (5-6 dried plums/d), participate in a 14-wk study, and meet all other inclusion/exclusion criteria, will be invited to participate. Study participants will be required to complete five visits as a part of the study. These visits consist of an initial visit to enter the study as well as pre- and post- visits for each arm (i.e., with or without dried plum supplementation) of the crossover study. Participant anthropometrics, dietary intake, physical activity will be assessed at baseline and monitored throughout the study. The primary outcomes will include change in circulating Th17 cells assessed using fluorescence-assisted cell sorting (FACS), their function evaluated utilizing ex vivo experiments with peripheral blood mononuclear cells, and serum IL-6 using a standard ELISA assay. Secondary outcomes will include alterations in Treg cells assessed using FACS as well as serum and fecal metabolites utilizing untargeted NMR-based metabolomics techniques and targeted analyses of short chain fatty acids employing LC/MS/MS techniques. Additionally, fecal microbiota taxa will be characterized using metabarcoded sequencing of the full-length of the 16S rRNA gene, and serum 25(OH)D, cytokines (TNF-α & IL-10), and the bone resorption marker, CTX-1 will be assessed. All primary and secondary outcomes will be assessed pre- and post- treatment for each arm of the study. For our primary outcomes, we will use linear mixed effects models to determine if the level of serum IL-6 and Th17 cells at the end of each treatment period is significantly different for dried plum compared to the control. Baseline measures, treatment and period indicators, vitamin D (i.e., serum 25-OH D), and important demographic characteristics (e.g., age, BMI, years post menopause) will be included as fixed effects. Random participant effects will be included to accommodate the correlations among repeated measures. We will also perform a per protocol analysis on the primary outcomes, which includes only those who completed the intervention and who were compliant (>85%) with the study protocol. Hypothesis tests for the treatment effect will be carried out following standard procedures for mixed-effects models. For secondary outcome measures (i.e., gut microbiota, metabolites, and bone resorption markers), we will use separate mixed effects models, adjusting for baseline, period, and demographic covariates. Categorical variables will be assessed using the generalized linear mixed-effects models. Importantly, to gain a better understanding of the gut-bone axis response, we will also integrate the immunologic outcomes (i.e., T cell), metabolomics, microbial taxa and bone biomarker data. These analyses will include regression analyses to correlate key outcomes. In addition, we will explore if dried plum consumption modulates the immune response via alterations in metabolite and microbiota profiles by conducting exploratory mediation analysis. All analyses will be performed with and without vitamin D considered as a covariate and the alpha will be set at 0.05. Efforts to disseminate our findings will include peer-review publications, presentations at professional meetings, the incorporation of our findings into formal classroom instruction, presentations to the relevant commodity boards and community speaking engagements to women's health groups. By increasing the awareness of our work we can increase the knowledge of our target audiences so that they can implement the information into their educational efforts and practice. The impact of our outcomes on the target audiences will beassessed based on outputs that include at least two peer-reviewed publications by members of our research team and presentations at 2-3 professional meetings demonstrating the collaborative work of this interdisciplinary team and the develop of new collaborations with investigators in this field. As an indicator of successful completion of the project, we will also generate a database that includes metabolomics and microbiota data that can be readily shared with members of the scientific community and others upon request.