Immunological Aspects of Eating Disorders

Risk factors for the development of eating disorders include infectious diseases such as streptococcal infection and autoimmune disorders like type 1 diabetes, rheumatoid arthritis, psoriasis, and inflammatory bowel disease. Acute, chronic, and social stress are potent influencers of the immune system. Infections, autoimmune diseases, and stress-related alterations in the immune system influence brain circuits and neurotransmitters involved in appetite and mood regulation by altering hormone and cytokine signalling which may predispose to or precipitate an eating disorder. Immunosuppressive treatment with glucocorticoids might lead to appetite and weight changes similar to those in eating disorders, and it can exacerbate the physical health consequences of an eating disorder, e.g., osteoporosis and sleep. The symptomatic behaviors of the various forms of eating disorders may result in over- or undernutrition leading to an extremely low or high body mass index (BMI). Chronic severe starvation and morbid obesity have been shown to have an impact on the balance of T-helper (Th) cells and other immune responses that are sensitive to nutritional status. This resulting imbalance may make patients with severe anorexia nervosa more susceptible to bacterial infections such as pneumonia or endocarditis, whereas people with obesity are more prone to suffer from viral infections such as influenza or COVID-19. Cross-sectional research on immunological biomarkers and research on immunological comorbidities have yielded contradictory results, potentially because confounding factors such as duration, severity, and the form of illness were not taken systematically into account. Genetic, epigenetic, and longitudinal clinical studies might unravel the linkages between immunological factors and eating disorders.