human saliva microbiome Genome sequencing

Suicide is the second leading cause of death in individuals between the ages of 10-34 in the United States. While the connection to the gut microbiota, immunity, and intestinal permeability has garnered increasing attention, our understanding of the role of oral flora in the systemic pathophysiology of depression is limited and, to our knowledge, links with suicidal ideation (SI) have not yet been explored in human populations. Emerging literature suggests that the oral microbiome may be leveraged for treatment and diagnosis of oral as well as systemic disease. Salivary microbiota and major histocompatibility complex (MHC) human leukocyte antigen (HLA) alleles were compared between 47 (12.6%) young adults with recent SI and 325 (87.4%) controls without recent SI. Several bacterial taxa were correlated with SI after controlling for sleep issues, diet, and genetics. To our knowledge, this is the first study to demonstrate a role for HLA genetics in SI and the potential for genetic and salivary bacterial interactions in the etiology of suicide.