Microbiome-mediated Weight, Anxiety, and Stress Dysregulation in Anorexia Nervosa

Anorexia nervosa (AN), a psychiatric disorder characterized by extreme weight dysregulation
commonly presents with comorbid anxiety. Therapeutic renourishment in AN is based primarily
on clinical opinion and guidelines, with a weak evidence base. Compelling data implicate the
intestinal microbiota in the regulation of adiposity and behavior, providing a strong
rationale for exploring the role of this complex microbial community in the emergence and
maintenance of, and recovery from AN. The overarching goal is to understand the precise
mechanism(s) by which intestinal bacteria contribute to dysregulation of adiposity, BMI,
anxiety, and stress in patients with AN. The investigators hypothesize that intestinal
microbiotas that arise from prolonged starvation contribute to increases in adiposity upon
refeeding and to persistently elevated anxiety and stress in individuals with AN. To test the
hypothesis the investigators propose 3 specific aims. In aim 1, the investigators will
identify the enteric bacterial groups associated with adiposity, BMI, anxiety, and stress in
AN patients. The investigators will characterize the intestinal microbiota in acutely low
weight AN patients (T1), in the same patients following weight restoration (T2), and in
healthy controls (HC) via high throughput sequencing of the 16S rRNA gene.

The investigators will compare the abundances of specific enteric taxa with adiposity, BMI
and behavior (anxiety and stress) in this study population. In aim 2, The investigators will
characterize the functional impact of the intestinal microbiota of AN patients on adiposity
and BMI when transplanted into germ free (GF) mice. The investigators will transplant
uncultured microbiotas from AN patients (at T1 and T2) and HC into GF mice and assess the
impact of enteric microbes on adiposity. In aim 3, the investigators will characterize the
functional impact of the intestinal microbiota of AN patients on anxiety and stress, and
molecular biomarkers of these behaviors, when transplanted into GF mice. The investigators
will transplant uncultured microbiotas from T1 AN patients and HC into GF mice and assess the
impact of enteric microbes on anxiety and stress. GF mice gavaged with sterile phosphate
buffer saline will be used as controls in aims 2 and 3. The proposed science is significant
in pioneering the combination of large scale 16S rRNA gene sequencing-based studies of
intestinal microbiotas in AN with exploration of their functional influence on adiposity and
behavioral traits associated with AN. The results will provide direction on how best to test
adjunct interventions for AN with pre-, pro-, anti-, or syn-biotics to enhance current
approaches to therapeutic weight restoration and improve treatment outcome. The science is
highly innovative as it will investigate an entirely novel factor in AN, the intestinal
microbiota, and use a novel approach to identify enteric microbes that impact adiposity and
behavior in this devastating illness. Additionally, the investigators will hope to study an
entirely novel factor (namely, the intestinal microbiota) as a contributor to the underlying
pathophysiology of AN.

Inclusion Criteria:

- Anorexia nervosa patient receiving treatment

Exclusion Criteria:

- history of gastrointestinal tract surgery

- history of inflammatory bowel diseases (IBD)

- history of irritable bowel syndrome (IBS)

- history of celiac disease

- history of any other diagnosis that could explain chronic or recurring bowel symptoms

- treatment in the last two months with antibiotics, non-steroid anti-inflammatory
agents, or steroids.

- eating disorders or other major psychiatric or medical issue (for healthy controls).