Honors Theses and Capstones

Date of Award

Spring 2023

Project Type

Senior Honors Thesis

College or School



Biomedical Sciences

Program or Major

Biomedical Sciences: Medical & Veterinary Sciences

Degree Name

Bachelor of Science

First Advisor

Dr. Maria Carlota Dao


The New Hampshire Bhutanese refugee population is disproportionately affected by obesity and metabolic disorders such as type 2 diabetes. The gut microbiome is important for overall human health, with high microbial richness and diversity being associated with reduced chronic inflammation and type 2 diabetes risk. Microbial richness and diversity have been shown to decrease in United States (U.S.) immigrant populations, but have not been measured in refugee populations. One of the anti-inflammatory functions of the gut microbiome is related to the production of short-chain fatty acids (SCFAs), which regulate pro-inflammatory cytokine production. Alpha-defensin 1 is an antimicrobial peptide that is a major player in the innate immune response to inflammation. This peptide is expressed at an increased rate when inflammation is present in the body, but is known to have decreased expression in individuals with obesity and type 2 diabetes (T2D) compared to individuals without metabolic disorder. The purpose of this thesis was to analyze the potential relationship between alpha-defensin 1 and gut microbiome species richness and diversity measures (Shannon-Wiener species diversity index, Inverse Simpson’s diversity index, and Fisher’s alpha diversity index) to see if T2D status affected the relationship between these variables. Additionally, the correlation between interleukin 6 (IL-6) and gut microbiome species richness and diversity was analyzed due to a previous finding that IL-6 and alpha-defensin 1 had a significant positive correlation. The fecal and plasma samples used to obtain the data in this project were collected from a volunteer population of 50 Bhutanese refugee adults who were residing in New Hampshire at the time of sample collection.