LAUSR

Previous studies have reported on the relationship between gut microbiota and major depressive disorder (MDD). However, there remain gaps in literature concerning the role of the intestinal barrier and microflora in the pathogenesis of depression. This study analyzes the potential causative relationship between gut microbiota and inflammatory and gut integrity markers and clinical symptoms in inpatients with depressive episodes. Sixteen inpatients (50% females) being treated with escitalopram (5-20 mg daily) in standardized conditions were included in the study. The composition of fecal microbiota was evaluated at baseline and endpoint using 16S rRNA sequencing. A significant correlation between depression severity was found, as measured with HDRS24 (Hamilton Depression Rating Scale-24 item), and the following abundance in bacteria: positive correlation with Paraprevotella (r = 0.80, q = 0.012), strong, negative correlations with Clostridiales (r = -0.70, q = 0.016), Clostridia (r = -0.71, q = 0.026), Firmicutes (r = -0.67. q = 0.032), and the RF32 order (r = -0.70, p = 0.016) in the Alphaproteobacteria (r = -0.66, q = 0.031). After six weeks of treatment, clinical outcomes were found to have a negative correlation with levels of plasma intestinal fatty acid-binding protein (IFABP) at the beginning of the study. Still they had a positive correlation with changes in fecal calprotectin during hospitalization. In conclusion, gut microbiota was associated with the severity of depressive symptoms. However, these findings do not serve as predictors of symptomatic improvement during antidepressant treatment in inpatient treatment for MDD. In turn, intestinal integrity and inflammation markers were associated with the response to treatment of patients with MDD and symptom severity. Additional studies are needed to confirm and extend these findings. CLINICAL TRIALS REGISTRATION: ISRCTN: 37389799.