Infants who require cardiopulmonary bypass for surgical repair of CHD are at high risk for secondary infections, which cause significant death and disability. The risk of secondary infection is increased by immune dysfunction. The intestinal microbiome calibrates immune function. Infants with CHD have substantial changes in their intestinal microbiome. We performed this scoping review to describe the current understanding of the relationship between the intestinal microbiome and immune function after pediatric cardiac surgery with cardiopulmonary bypass.

We searched the PubMed, Cumulative Index to Nursing and Allied Health Literature, Cochrane, and Scopus databases with the assistance of a medical librarian. We included trials that analysed intestinal microbiome composition and immune function after cardiac surgery with cardiopulmonary bypass in infants.

We found two observational cohorts and two interventional trials describing composition of intestinal microbiome and some measures of immune function after heart surgery with cardiopulmonary bypass in infants. A total of 114 children were analysed. Three trials were exclusively in infants, and one was in older children and infants. All trials found a differential composition of the intestinal microbiome in infants with CHD compared to those without CHD, and one described a robust correlation between composition of the intestinal microbiome with cytokine profile and adverse outcomes.

Despite robust preclinical data and data from other disease states, there is minimal data about the correlation between immune function and intestinal microbiome composition in infants with CHD after cardiopulmonary bypass.

The pathogenesis of schizophrenia is multidimensional and intensively studied. The gut–brain axis disturbances might play a significant role in the development of schizophrenia.

We compared the gut microbiota of 53 individuals with schizophrenia and 58 healthy controls, using the 16S rRNA sequencing method. Individuals with schizophrenia were assessed using the following scales: the Positive and Negative Syndrome Scale, the Calgary Depression Scale for Schizophrenia, the Social and Occupational Functioning Assessment Scale and the Repeatable Battery for the Assessment of Neuropsychological Status.

No significant between-group differences in α-diversity measures were observed. Increased abundance of Lactobacillales (order level), Bacilli (class level) and Actinobacteriota (phylum level) were found in individuals with schizophrenia regardless of potential confounding factors, and using two independent analytical approaches (the distance-based redundancy analysis and the generalised linear model analysis). Additionally, significant correlations between various bacterial taxa (the Bacteroidia class, the Actinobacteriota phylum, the Bacteroidota phylum, the Coriobacteriales order and the Coriobacteria class) and clinical manifestation (the severity of negative symptoms, performance of language abilities, social and occupational functioning) were observed.

The present study indicates that gut microbiota alterations are present in European patients with schizophrenia. The abundance of certain bacterial taxa might be associated with the severity of negative symptoms, cognitive performance and general functioning. Nonetheless, additional studies are needed before the translation of our results into clinical practice.

The microbiota–gut–brain axis, especially the microbial tryptophan (Trp) biosynthesis and metabolism pathway (MiTBamp), may play a critical role in the pathogenesis of major depressive disorder (MDD). However, studies on the MiTBamp in MDD are lacking. The aim of the present study was to analyze the gut microbiota composition and the MiTBamp in MDD patients.

We performed shotgun metagenomic sequencing of stool samples from 26 MDD patients and 29 healthy controls (HCs). In addition to the microbiota community and the MiTBamp analyses, we also built a classification based on the Random Forests (RF) and Boruta algorithm to identify the gut microbiota as biomarkers for MDD.

The Bacteroidetes abundance was strongly reduced whereas that of Actinobacteria was significantly increased in the MDD patients compared with the abundance in the HCs. Most noteworthy, the MDD patients had increased levels of Bifidobacterium, which is commonly used as a probiotic. Four Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologies (KOs) (K01817, K11358, K01626, K01667) abundances in the MiTBamp were significantly lower in the MDD group. Furthermore, we found a negative correlation between the K01626 abundance and the HAMD scores in the MDD group. Finally, RF classification at the genus level can achieve an area under the receiver operating characteristic curve of 0.890.

The present findings enabled a better understanding of the changes in gut microbiota and the related Trp pathway in MDD. Alterations of the gut microbiota may have the potential as biomarkers for distinguishing MDD patients form HCs.