Interaction of the gut microbiota and brain functional connectivity in late-life depression.

BACKGROUND: Increasing evidence suggests an important role of the gut microbiome in the pathogenesis of mental disorders, including depression, along the microbiota-gut-brain axis. We sought to explore the interactions between gut microbe composition and neural circuits in late-life depression (LLD). METHODS: We performed fecal 16S ribosomal RNA (rRNA) sequencing and resting-state functional magnetic resonance imaging in a case-control cohort of older adults with LLD and healthy controls to characterize the association between gut microbiota and brain functional connectivity (FC). We used the Hamilton Depression Rating Scale (HAMD) to assess depressive symptoms. RESULTS: We included 32 adults with LLD and 16 healthy controls. At the genus level, the relative abundance of Enterobacter, Akkermansiaceae, Hemophilus, Burkholderia, and Rothia was significantly higher among patients with LDD than controls. Reduced FC within mood regulation circuits was mainly found in the frontal cortex (e.g., the right superior and inferior frontal gyrus, right lateral occipital cortex, left middle frontal gyrus, and left caudate) among patients with MDD. Group-characterized gut microbes among controls and patients showed opposite correlations with seed-based FC, which may account for the aberrant emotion regulation among patients with LDD. The abundance of Enterobacter (dominant genus among patients with LLD) was positively correlated with both HAMD scores (r = 0.49, p = 0.0004) and group-characterized FC (r = -0.37, p < 0.05), while Odoribacter (dominant genus among controls) was negatively correlated with both HAMD scores (r = -0.30, p = 0.04) and group-characterized FC. LIMITATIONS: The study's cross-sectional design and small sample size limit causal inferences; larger longitudinal studies are required for detailed subgroup analyses. CONCLUSION: We identified significant correlations between LDD-characterized gut microbes and brain FC, as well as depression severity, which may contribute to the pathophysiology of depression development among patients with LLD. Specific microbes were linked to altered brain connectivity, suggesting potential targets for treating LLD.

Differences in gut microbiota correlate with symptoms and regional brain volumes in patients with late-life depression.

Depression is associated with gut dysbiosis that disrupts a gut-brain bidirectional axis. Gray matter volume changes in cortical and subcortical structures, including prefrontal regions and the hippocampus, have also been noted in depressive disorders. However, the link between gut microbiota and brain structures in depressed patients remains elusive. Neuropsychiatric measures, stool samples, and structural brain images were collected from 36 patients with late-life depression (LLD) and 17 healthy controls. 16S ribosomal RNA (rRNA) gene sequencing was used to profile stool microbial communities for quantitation of microbial composition, abundance, and diversity. T1-weighted brain images were assessed with voxel-based morphometry to detect alterations in gray matter volume between groups. Correlation analysis was performed to identify the possible association between depressive symptoms, brain structures and gut microbiota. We found a significant difference in the gut microbial composition between patients with late-life depression (LLD) and healthy controls. The genera Enterobacter and Burkholderia were positively correlated with depressive symptoms and negatively correlated with brain structural signatures in regions associated with memory, somatosensory integration, and emotional processing/cognition/regulation. Our study purports the microbiota-gut-brain axis as a potential mechanism mediating the symptomatology of LLD patients, which may facilitate the development of therapeutic strategies targeting gut microbes in the treatment of elderly depressed patients.

Paradox of trimethylamine-N-oxide, the impact of malnutrition on microbiota-derived metabolites and septic patients.

BACKGROUND: Trimethylamine N-oxide (TMAO) is a microbiota-derived metabolite, which is linked to vascular inflammation and atherosclerosis in cardiovascular (CV) diseases. But its effect in infectious diseases remains unclear. We conducted a single-center prospective study to investigate association of TMAO with in-hospital mortality in septic patients admitted to an intensive care unit (ICU). METHODS: Totally 95 septic, mechanically ventilated patients were enrolled. Blood samples were obtained within 24 h after ICU admission, and plasma TMAO concentrations were determined. Septic patients were grouped into tertiles according to TMAO concentration. The primary outcome was in-hospital death, which further classified as CV and non-CV death. Besides, we also compared the TMAO concentrations of septic patients with 129 non-septic patients who were admitted for elective coronary angiography (CAG). RESULTS: Septic patients had significantly lower plasma TMAO levels than did subjects admitted for CAG (1.0 vs. 3.0 µmol/L, p < 0.001). Septic patients in the lowest TMAO tertile (< 0.4 µmol/L) had poorer nutrition status and were given longer antibiotic courses before ICU admission. Circulating TMAO levels correlated positively with daily energy intake, the albumin and prealbumin concentration. Compared with those in the highest TMAO tertile, septic patients in the lowest TMAO tertile were at greater risk of non-CV death (hazard ratio 2.51, 95% confidence interval 1.21-5.24, p = 0.014). However, TMAO concentration was no longer an independent predictor for non-CV death after adjustment for disease severity and nutritional status. CONCLUSION: Plasma TMAO concentration was inversely associated with non-CV death among extremely ill septic patients, which could be characterized as TMAO paradox. For septic patients, the impact of malnutrition reflected by circulating TMAO levels was greater than its pro-inflammatory nature.

Association between gastrointestinal symptoms and depression among older adults in Taiwan: A cross-sectional study.

BACKGROUND: Older adults with depression more frequently experience somatic and gastrointestinal (GI) problems compared with people without depression and younger adults with depression. However, whether GI symptoms are predictive of elevated rates of depression among older adults is unclear. METHODS: We enrolled 106 older adults (>60 years old); 69 had late-life depression (LLD), and 37 were controls. All participants gave ratings on the Gastrointestinal Symptom Rating Scale (GSRS) and Hamilton Depression Rating Scale. Food consumption was assessed using a food frequency questionnaire, and a Mediterranean diet score was used as a covariate. RESULTS: Compared with the controls, patients with LLD reported higher levels of depressive and GI symptoms and reported more reflux, abdominal pain, and dyspepsia symptoms, and these symptoms were correlated with Hamilton Depression Rating Scale scores (GSRS total: ß = 0.47; reflux: ß = 1.47; abdominal pain: ß = 1.98; dyspepsia: ß = 1.02; all p < 0.01). After demographic variables and Mediterranean diet score were controlled for, a logistic regression analysis indicated that total GSRS score was an independent determinant of LLD (odds ratio: 1.20, 95% CI: 1.04-1.38). Moreover, a stratified analysis by depression severity indicated that higher total GSRS score may contribute to greater depression severity (odds ratio: 1.25, 95% CI: 1.04-1.52). CONCLUSION: We provide evidence that GI symptoms are associated with depressive symptoms among patients with LLD. Older people with more specific GI symptoms, such as reflux, abdominal pain, and dyspepsia, are potentially at greater risk of having LLD.

Lipid paradox in patients with acute myocardial infarction: Potential impact of malnutrition.

BACKGROUND & AIMS: Aggressive lipid reduction is recommended for patients with AMI, but reverse epidemiology, the lipid paradox, has been reported in several clinical studies. The cause of lipid paradox remains uncertain, and nutrition is one possible explanation. In this single-center retrospective study, we investigated the relationships between baseline LDL concentrations and clinical outcomes in patients with AMI, stratified by different nutritional status. METHODS: Totally 409 patients were enrolled for analysis. The Nutritional Risk Index (NRI) was used to estimate the risk of malnutrition. Subjects were grouped into tertiles according to their NRIs. Clinical outcomes were compared among patients with varying NRIs and LDL levels. RESULTS: Patients in the lowest NRI tertile had increased incidences of in-hospital mortality, cardiogenic shock, decompensated heart failure, renal failure, and sepsis. This tertile was also associated with increased long-term mortality during the follow-up period of 832 ± 744 days. Mortality was increased among patients with baseline LDL concentrations ≤70 mg/dL in the lowest NRI tertile (log rank test, p = 0.0257), but not in the high or median tertiles. Moreover, baseline LDL level ≤70 mg/dL was an independent risk factor of all-cause mortality (adjusted hazard ratio = 1.73; 95% confidence interval, 1.01-2.94; p = 0.045) in the lowest NRI tertile. CONCLUSIONS: Lipid paradox was observed in the high-risk of malnutrition population among patients with AMI. Aggressive lipid-lowering therapy is still recommended for patients with AMI and fair nutritional status. However, when treating patients at high risk of malnutrition, the improvement of nutritional status may be more beneficial than strict LDL control.

Hot water extracted Lycium barbarum and Rehmannia glutinosa inhibit liver inflammation and fibrosis in rats.

Polysaccharide-rich Lycium barbarum and Rehmannia glutinosa have been considered to have immune-modulating activity. This study investigated the effects of water extracted Lycium barbarum and Rehmannia glutinosa (HE) on carbon tetrachloride (CCl(4))-induced liver injury in rats. Male Sprague-Dawley rats were randomly divided into: normal diet + peritoneal injection of olive oil (control), normal diet + CCl(4) injection (CCl(4)), 1 × HE (0.05% HE for each) + CCl(4) (1 × HE), and 3 × HE (0.15% HE for each) + CCl(4) (3 × HE) groups. Rats were injected with 40% CCl(4) at a dose of 0.75 ml/kg body weight once a week for seven weeks, one week after herbal extract treatment. After eight week herbal extract treatment, pathohistological examination showed that both 1× and 3 × HE treatments diminished necrotic hepatocytes, chemoattraction of inflammatory cells, and liver fibrosis. Both 1× and 3 × HE treatments decreased plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, and reduced hepatic levels of pro-inflammatory cytokines - tumor necrosis factor-α and interleukin-1ß - compared to CCl(4) treatment alone. The 1 × HE treatment increased hepatic anti-inflammatory cytokine IL-10 levels. Both the 1× and 3 × HE treatments suppressed liver fibrosis biomarkers - transforming growth factor-ß1 and hydroxyproline. Therefore, treatment with water extracted Lycium barbarum and Rehmannia glutinosa (0.05% and 0.15% for each) for eight weeks protects against necrotic damage, indicated by decreases in plasma ALT and AST activities, and suppresses liver fibrosis by down-regulation of liver inflammation in rats with CCl(4)-induced liver injury.