Decoding the neurocircuitry of gut feelings: Region-specific microbiome-mediated brain alterations

Short-Term Ingestion of Essential Amino Acid Based Nutritional Supplements or Whey Protein Improves the Physical Function of Older Adults Independently of Gut Microbiome

SCOPE

Dietary proteins and essential amino acids (EAAs) are the major nutritional supplements that support the growth and activity of gut microbes contributing to the wellbeing of their host. This study hypothesizes that daily supplementation of the diet with either EAAs or whey protein for 12 weeks would improve the gut microbiome of older adults.

METHODS AND RESULTS

The stool samples are processed and subjected to Illumina-based 16S ribosomal ribonucleic acid (rRNA) gene amplicon sequencing. In both groups, the most abundant families are found in order of relative abundance included: Bacteroidaceae, Lachnospiraceae, Ruminococcaceae, Prevotellaceae, Rikenellaceae, Enterobacteriaceae, Oscillospiraceae, Tannerellaceae, and Akkermansiaceae, which indicate that these subjects are able to maintain a same healthy microbial diversity in their guts. A significant finding is a reduction of proinflammatory cytokine, interleukin-18 (IL-18) in the EAAs group. It also uses the standard 6-min walking test (6MWT) as a measure of cardiopulmonary fitness. At the end of the study, the subjects in the EAAs group perform significantly better in the 6MWT as compared to the whey group.

CONCLUSION

It seems plausible that the improved physical performance and reduced proinflammatory cytokine, IL-18 seen in the EAAs group, are independent of changes in gut microbiota.

The gut virome is associated with stress-induced changes in behaviour and immune responses in mice

The microbiota-gut-brain axis has been shown to play an important role in the stress response, but previous work has focused primarily on the role of the bacteriome. The gut virome constitutes a major portion of the microbiome, with bacteriophages having the potential to remodel bacteriome structure and activity. Here we use a mouse model of chronic social stress, and employ 16S rRNA and whole metagenomic sequencing on faecal pellets to determine how the virome is modulated by and contributes to the effects of stress. We found that chronic stress led to behavioural, immune and bacteriome alterations in mice that were associated with changes in the bacteriophage class Caudoviricetes and unassigned viral taxa. To determine whether these changes were causally related to stress-associated behavioural or physiological outcomes, we conducted a faecal virome transplant from mice before stress and autochthonously transferred it to mice undergoing chronic social stress. The transfer of the faecal virome protected against stress-associated behaviour sequelae and restored stress-induced changes in select circulating immune cell populations, cytokine release, bacteriome alterations and gene expression in the amygdala. These data provide evidence that the virome plays a role in the modulation of the microbiota-gut-brain axis during stress, indicating that these viral populations should be considered when designing future microbiome-directed therapies.

Adolescence and the Microbiome: Implications for Healthy Growth and Maturation

The gut microbiota was initially thought to develop into a stable, adult-like profile during early postnatal life. The formation of the gut microbiota during early life has been shown to contribute to healthy growth and has lifelong implications for host health. Adolescence, the developmental period between childhood and adulthood, is a critical window for healthy growth and maturation. The composition of the gut microbiota in adolescents is distinct from that of children and adults, which supports the premise that the gut microbiota continues to develop during adolescence toward an adult-like profile. Research has begun to shift its focus from understanding the gut microbiome at the extremes of the life span to evaluating the importance of the gut microbiome during adolescence and its role in healthy development. This article provides an overview of adolescent development, host-microbiota interactions, and experimental models used to discern effects of gut microbiota on health and disease. Herein, the role of the gut microbiota is reviewed as it relates to adolescent: i) brain development, cognition, and behavior; ii) metabolism and adiposity; and iii) skeletal growth and bone mass accrual. Future directions are addressed, including omics investigations defining mechanisms through which the gut microbiota influences adolescent development. Furthermore, we discuss advancing noninvasive interventions targeting the adolescent gut microbiota that could be employed to support healthy growth and maturation.

Physiological and cognitive changes after treatments of cyclophosphamide, methotrexate, and fluorouracil: implications of the gut microbiome and depressive-like behavior

Introduction

Chemotherapy-induced cognitive impairment colloquially referred to as chemobrain is a poorly understood phenomenon affecting a highly variable proportion of patients with breast cancer. Here we investigate the association between anxiety and despair-like behaviors in mice treated with cyclophosphamide, methotrexate, and fluorouracil (CMF) along with host histological, proteomic, gene expression, and gut microbial responses.

Methods

Forced swim and sociability tests were used to evaluate depression and despair-like behaviors. The tandem mass tag (TMT) proteomics approach was used to assess changes in the neural protein network of the amygdala and hippocampus. The composition of gut microbiota was assessed through 16S rRNA gene sequencing. Finally, quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to evaluate changes in intestinal gap junction markers.

Results and discussion

We observed that CMF induced social and despair-like behavior in mice 96 hours following treatment. Proteomic analysis identified changes in various proteins related to progressive neurological disease, working memory deficit, primary anxiety disorder, and gene expression revealing increases in NMDA and AMPA receptors in both the hippocampus and the amygdala because of CMF treatment. These changes finally, we observed immediate changes in the microbial population after chemotherapy treatment, with a notable abundance of Muribaculaceae and Romboutsia which may contribute to changes seen in the gut.

The interconnection between obesity and executive function in adolescence: The role of the gut microbiome

In the United States, adolescent obesity is a growing epidemic associated with maladaptive executive functioning. Likewise, data link the microbiome to obesity. Emerging microbiome research has demonstrated an interconnection between the gut microbiome and the brain, indicating a bidirectional communication system within the gut-microbiome-brain axis in the pathophysiology of obesity. This narrative review identifies and summarizes relevant research connecting adolescent obesity as it relates to three core domains of executive functioning and the contribution of the gut microbiome in the relationship between obesity and executive functions in adolescence. The review suggests that (1) the interconnection between obesity, executive function, and the gut microbiome is a bidirectional connection, and (2) the gut microbiome may mediate the neurobiological pathways between obesity and executive function deficits. The findings of this review provide valuable insights into obesity-associated executive function deficits and elucidate the possible mediation role of the gut microbiome.

Lactobacillus maintains IFNγ homeostasis to promote behavioral stress resilience

The gut microbiome consists of the trillions of bacteria, fungi, and viruses that inhabit the digestive tract. These communities are sensitive to disruption from environmental exposures ranging from diet changes to illness. Disruption of the community of lactic acid producing bacteria, Lactobaccillacea , has been well documented in mood disorders and stress exposure. In fact, oral supplement with many Lactobacillus species can ameliorate these effects, preventing depression- and anxiety-like behavior. Here, for the first time, we utilize a gnotobiotic mouse colonized with the Altered Schaedler Flora to remove the two native species of Lactobaccillacea . Using this novel microbial community, we found that the Lactobacillus species themselves, and not the disrupted microbial communities are protective from environmental stressors. Further, we determine that Lactobaccillacea are maintaining homeostatic IFNγ levels which are mediating these behavioral and circuit level responses. By utilizing the Altered Schaedler Flora, we have gained new insight into how probiotics influence behavior and give novel methods to study potential therapies developed to treat mood disorders.