Alcohol-associated diseases and disorders (AAD) account for over 5% of global health problems. AAD is more common among veterans, and more than 30% of young men in the military are heavy drinkers, twice as much as their civilian counterparts. Alcohol misuse is high in veterans exposed to combat-related traumatic stress or experiencing post-traumatic stress disorder (PTSD). AAD and PTSD symptoms feedback into one another and impede the recovery from both disorders. Therefore, treating AAD patients comorbid with PTSD is complicated and requires a deeper understanding of the cross-talk between alcohol and stress. Behavioral intervention is not efficacious in moderate to heavy alcohol drinkers, and its benefit in PTSD is inconsistent. The common conditions associated with AAD and PTSD are endotoxemia and systemic inflammation. Clinical and experimental evidence indicates that intestinal dysbiosis (depleted beneficial species, increased pathobionts, and decreased diversity) is necessary for developing endotoxemia and systemic inflammation. Therefore, dysbiosis is a crucial therapeutic target for treating AAD and PTSD. The critical barrier in this field is that the mechanisms involved in alcohol and stress-induced dysbiosis are poorly defined. There is no treatment with clear evidence of efficacy available for treating AAD or AAD comorbid with PTSD. Our long-term goal is to describe the pathophysiology of AAD-stress comorbidity and develop novel therapeutic strategies by targeting the gut microbiota. Our preliminary studies have identified that: 1) chronic restraint stress (CRS) and corticosterone exacerbate ethanol (EtOH)-induced gut barrier dysfunction, endotoxemia, systemic inflammation, liver damage, and neuroinflammation in mice. 2) Corticosterone reinforces EtOH-induced dysbiosis and depletion of Paneth cell a-defensin mRNA. 3) Deleting intestinal glucocorticoid receptor (GR) prevents corticosterone and EtOH-induced gut permeability and systemic response. 4) Knockout of intestinal NR3C1 (encoding GR) prevents corticosterone and EtOH-induced defensin mRNA depletion and dysbiosis. 5) Corticosterone and EtOH reduce intestinal mRNA for T-cell receptor 4 (TCF4), the transcription factor required for a-defensin production. These findings form the scientific premise and support the central hypothesis that the Paneth cell GR drives stress and alcohol-associated dysbiosis, gut permeability, and systemic responses by suppressing a-defensin production. Our overall objective is to define the role of Paneth cell GR and the downstream mechanism in stress and alcohol-associated organ damage and identify the therapeutic potential of a-defensins in treating AAD comorbid with chronic stress. This objective will be achieved by determining that 1) Paneth cell GR is required for stress and alcohol-induced TCF4 down- regulation, a-defensin depletion, and microbiota dysbiosis. 2) TCF4 down-regulation mediates GR's role in stress and alcohol-induced a-defensin depletion...