Exploration of the Gut Microbiome in Thai Patients with Major Depressive Disorder Shows a Specific Bacterial Profile with Depletion of the Ruminococcus Genus as a Putative Biomarker

Abstract

Maes et al. (2008) published the first paper demonstrating that major depressive disorder (MDD) is accompanied by abnormalities in the microbiota–gut–brain axis, as evidenced by elevated serum IgM/IgA to lipopolysaccharides (LPS) of Gram-negative bacteria, such as Morganella morganii and Klebsiella Pneumoniae. The latter aberrations, which point to increased gut permeability (leaky gut), are linked to activated neuro-immune and oxidative pathways in MDD. To delineate the profile and composition of the gut microbiome in Thai patients with MDD, we examined fecal samples of 32 MDD patients and 37 controls using 16S rDNA sequencing, analyzed α- (Chao1 and Shannon indices) and β-diversity (Bray–Curtis dissimilarity), and conducted linear discriminant analysis (LDA) effect size (LEfSe) analysis. Neither α- nor β-diversity differed significantly between MDD and controls. Rhodospirillaceae, Hungatella, Clostridium bolteae, Hungatella hathewayi, and Clostridium propionicum were significantly enriched in MDD, while Gracillibacteraceae family, Lutispora, and Ruminococcus genus, Ruminococcus callidus, Desulfovibrio piger, Coprococcus comes, and Gemmiger were enriched in controls. Contradictory results have been reported for all these taxa, with the exception of Ruminococcus, which is depleted in six different MDD studies (one study showed increased abundance), many medical disorders that show comorbidities with MDD, and animal MDD models. Our results may suggest a specific profile of compositional gut dysbiosis in Thai MDD patients, with increases in some pathobionts and depletion of some beneficial microbiota. The results suggest that depletion of Ruminococcus may be a more universal biomarker of MDD that may contribute to increased enteral LPS load, LPS translocation, and gut–brain axis abnormalities.

Gastrointestinal Microbiota & Symptoms of Depression and Anxiety in Anorexia Nervosa—A Re-Analysis of the MICROBIAN Longitudinal Study

“…They found that models adjusted for BMI and age were highly correlated with unadjusted analysis, indicating that BMI and age have little influence on the relationship between microbiota and common diseases [ 60 ]. Also, Maes et al did not find the effects of BMI, sex, age, and drug state in regression analysis with isometric log-ratio transformed the abundance of gut bacteria in patients with major depression disorder [ 61 ]. However, it needs to be mentioned that the mean BMI in both studies were in the slightly overweight range [ 60 , 61 ], thus these populations are not comparable with a malnourished, underweight population.…”

“…Also, Maes et al did not find the effects of BMI, sex, age, and drug state in regression analysis with isometric log-ratio transformed the abundance of gut bacteria in patients with major depression disorder [ 61 ]. However, it needs to be mentioned that the mean BMI in both studies were in the slightly overweight range [ 60 , 61 ], thus these populations are not comparable with a malnourished, underweight population. Also, Rong et al analyzed the relationship between BMI and gastrointestinal microbiota in patients with major depression disorder with a mean BMI of 21.5 [ 62 ].…”

Premature Infant Gut Microbiome relationships with childhood behavioral scales: preliminary insights

“…A lower abundance of Ruminococcus was related to higher scores in the depression DSM-related scale of the CBCL. Major Depressive Disorder in adults was associated with lower abundance of Ruminococcus ( 41 ). Contradictory results have been reported for other taxa, but not for Ruminococcus ( 41 ), indicating that this microbe may be a potential biomarker for depressive disorder.…”

Role of Inflammatory Mechanisms in Major Depressive Disorder: From Etiology to Potential Pharmacological Targets

“…Imbalances in gut microbiota homeostasis, including alterations in microbiota composition and specific taxa, can lead to gut dysbiosis, resulting not only in peripheral inflammation, but also in neuroinflammation, reduced BBB integrity, neuronal death, microglia dysfunction, and depressive symptoms [ 194 , 204 , 209 ]. Accordingly, recent studies have shown differences in the gut microbiota of MDD-afflicted individuals as compared to healthy controls [ 210 , 211 , 212 , 213 , 214 , 215 , 216 , 217 , 218 ].…”

“…Conversely, FMT from healthy donors or sulfasalazine treatment alleviated the depressive-like behaviors induced by FMT from IBD plus MDD patients, while also reducing pro-inflammatory markers in the serum and colon of these mice [ 227 ]. In addition, administration of Lactobacillus plantarum NK151, Bifidobacterium longum NK173, and Bifidobacterium bifidum NK175 alleviated depression-like behaviors induced by FMT from IBD plus depression patients, while also normalizing hippocampal NF-κB + Iba1 + cell numbers, IL-1β and IL-6 expression, serum levels of LPS, IL-6, and creatinine, as well as colonic NF-κB + CD11c + cell numbers and IL-1β and IL-6 expression in these mice [ 218 ]. Other preclinical studies have also evaluated colitis and the occurrence of depressive-like behaviors in dextran sulfate sodium (DSS)-treated mice [ 226 , 228 ].…”