Anti-inflammatory effects of cocoa supplementation in a mice model of inflammatory bowel disease

Open Access
- Author:
- Coleman, Kiana
- Graduate Program:
- Food Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- January 12, 2022
- Committee Members:
- Robert Roberts, Program Head/Chair
Joshua D Lambert, Thesis Advisor/Co-Advisor
Ramaswamy C Anantheswaran, Committee Member
Greg Ziegler, Committee Member - Keywords:
- Inflammatory Bowel Disease
Ulcerative colitis
Inflammation
Dose-response
Cocoa
In vivo - Abstract:
- Inflammatory bowel disease (IBD) afflicts nearly 2.2 million people worldwide. IBD is composed of two main conditions, ulcerative colitis (UC) and Crohn’s disease. UC has an incidence of 9–20 cases per 100,000 people per year and a prevalence of 156–291 cases per 100,000 people per year. In addition to the decrease in health-related quality of life and increases in hospitalizations, IBD also presents a significant financial burden. In 2014, the estimated direct medical costs were $11-28 billion and the continued increase in prevalence has led to further increases. UC patients suffer from moderate to severe gastrointestinal issues hindering their way of life as it becomes more difficult to absorb and metabolize essential nutrients from their already restricted diet. Patients exhibit increased inflammatory gene expression, cytokine production, oxidative stress, and decreased gut barrier function. Inflammation in UC is a result of antigen-presenting cells in the colonic mucous membrane over-producing pro-inflammatory cytokines. Cocoa has been reported to have antioxidant and anti-inflammation activity. The effects have been linked to cocoa polyphenols, which represent 12–18% of dry weight of cocoa powder. The overall goal of this project was to investigate the dose-dependent beneficial effects of dietary cocoa supplementation on dextran sulfate sodium (DSS)-induced UC in C57BL/6J mice. The DSS-induced mouse model is widely used because it mimics the pathogenesis of UC in humans. The specific objectives of the current study were a) to evaluate the effect of a diet supplemented with cocoa on gross markers of UC and b) to evaluate the effect of this cocoa supplementation on molecular markers of systemic and colonic inflammation. Male C57BL/6J mice were pre-treated with cocoa supplemented diets (0, 2, 4, and 8% w/w) for two weeks prior to receiving DSS (2% w/v) in drinking water for 7 days to induce ulcerative colitis. Cocoa treatment continued throughout the induction period. Body weight was determined during the DSS induction period. At the end of the study, body weights were reduced in the 8% cocoa treated mice compared to the control (11.2% lower final body weight, p < 0.05). After euthanasia, spleen and liver weight, and colon length were determined. It was found that cocoa-treated mice at all doses had reduced spleen weight compared to DSS-treated control mice (35 – 40% lower). Mice treated with 8% cocoa had 20% lower liver weights. No significant difference in colon length was observed between cocoa-treated mice and DSS-induced controls. Plasma protein levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, chemokine ligand 1 (CXCL1), and interferon (IFN)-γ were determined by multiplex ELISA. Colonic mRNA levels of the inflammatory markers, IL-1β, IL-6, IL-10, and TNF-α were determined by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Up-regulation of serum markers of inflammation TNF-α, IL-1β, CXCL1, and IFN-γ were seen in the mice that received cocoa intervention compared to DSS-treated mice, as measured by Multiplex ELISA assay. Colonic gene expression of IL-1β, IL-6, IL-10, and TNF-α were not significantly different from DSS-treated control mice. Principal component analysis showed that the mice in the 8% treatment group were significantly different from the other treatment groups, and that this difference was driven mainly by higher levels of plasma TNF-α and IL-1β. Collectively, the results of this study demonstrate that dietary treatment with cocoa was not able to reduce inflammation and may enhance inflammation in the DSS-induced mouse model of UC. Future studies should examine the mechanisms of action underlying the effects observed here.