Background and aims

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been reported in irritable bowel syndrome (IBS). Enhanced HPA axis response has been associated with reduced glucocorticoid receptor (GR) mediated negative feedback inhibition. We aimed to study the effects of IBS status, sex, or presence of early adverse life events (EAL) on the cortisol response to corticotropin-releasing factor (CRF) and adrenocorticotropic hormone (ACTH), and on GR mRNA expression in peripheral blood mononuclear cells (PBMCs).

Methods

Rome III+ IBS patients and healthy controls underwent CRF (1μg/kg ovine) and ACTH (250μg) stimulation tests with serial plasma ACTH and cortisol levels measured (n=116). GR mRNA levels were measured using quantitative PCR (n=143). Area under the curve (AUC) and linear mixed effects models were used to compare ACTH and cortisol response measured across time between groups.

Results

There were divergent effects of IBS on the cortisol response to ACTH by sex. In men, IBS was associated with an increased AUC (p=0.009), but in women AUC was blunted in IBS (p=0.006). Men also had reduced GR mRNA expression (p=0.007). Cumulative exposure to EALs was associated with an increased HPA response. Lower GR mRNA was associated with increased pituitary HPA response and increased severity of overall symptoms and abdominal pain in IBS.

Conclusion

This study highlights the importance of considering sex in studies of IBS and the stress response in general. Our findings also provide support for PBMC GR mRNA expression as a peripheral marker of central HPA response.

Background

Cardiometabolic disease (CMD) disproportionately affects African American/Black (AA) and Latino communities. CMD disparities are exacerbated by their underrepresentation in clinical trials for CMD treatments including nutritional interventions. The study aimed to (1) form a precision nutrition community consultant panel (PNCCP) representative of Latino and AA communities in Los Angeles to identify barriers and facilitators to recruitment and retention of diverse communities into nutrition clinical trials and (2) develop culturally informed strategies to improve trial diversity.

Methods

A deliberative community engagement approach was used to form a PNCCP for the Nutrition for Precision Health (NPH) trial, part of the of the All of Us research initiative. The PNCCP included individuals that provide services for Latino and AA communities who met during 11 virtual sessions over 1 year. Discussion topics included enhancing recruitment and cultural acceptance of the NPH trial. We summarized CCP recommendations by theme using an inductive qualitative approach.

Results

The PNCCP included 17 adults (35% AA, 47% Latino). Four thematic recommendations emerged: reducing structural barriers to recruitment, the need for recruitment materials to be culturally tailored and participant-centered, community-engaged trial recruitment, and making nutrition trial procedures inclusive and acceptable. We outlined the study response to feedback, including the constraints that limited implementation of suggestions.

Conclusion

This study centers community voices regarding the recruitment and retention of AA and Latino communities into a nutrition clinical trial. It highlights the importance of community engagement early on in protocol development and maintaining flexibility to enhance inclusion of diverse communities in nutrition clinical trials.