Oral Administration of 5-Hydroxytryptophan Restores Gut Microbiota Dysbiosis in a Mouse Model of Depression

The Influence of Cecal Microbiota Transplantation on Chicken Injurious Behavior: Perspective in Human Neuropsychiatric Research

Numerous studies have evidenced that neuropsychiatric disorders (mental illness and emotional disturbances) with aggression (or violence) pose a significant challenge to public health and contribute to a substantial economic burden worldwide. Especially, social disorganization (or social inequality) associated with childhood adversity has long-lasting effects on mental health, increasing the risk of developing neuropsychiatric disorders. Intestinal bacteria, functionally as an endocrine organ and a second brain, release various immunomodulators and bioactive compounds directly or indirectly regulating a host's physiological and behavioral homeostasis. Under various social challenges, stress-induced dysbiosis increases gut permeability causes serial reactions: releasing neurotoxic compounds, leading to neuroinflammation and neuronal injury, and eventually neuropsychiatric disorders associated with aggressive, violent, or impulsive behavior in humans and various animals via a complex bidirectional communication of the microbiota-gut-brain (MGB) axis. The dysregulation of the MGB axis has also been recognized as one of the reasons for the prevalence of social stress-induced injurious behaviors (feather pecking, aggression, and cannibalistic pecking) in chickens. However, existing knowledge of preventing and treating these disorders in both humans and chickens is not well understood. In previous studies, we developed a non-mammal model in an abnormal behavioral investigation by rationalizing the effects of gut microbiota on injurious behaviors in chickens. Based on our earlier success, the perspective article outlines the possibility of reducing stress-induced injurious behaviors in chickens through modifying gut microbiota via cecal microbiota transplantation, with the potential for providing a biotherapeutic rationale for preventing injurious behaviors among individuals with mental disorders via restoring gut microbiota diversity and function.

Baseline gut microbiota profiles affect treatment response in patients with depression

The role of the gut microbiota in the pathophysiology of depression has been explored in numerous studies, which have confirmed that the baseline gut microbial profiles of patients with depression differ from those of healthy individuals. The gut microbiome affects metabolic activity in the immune and central nervous systems and regulates intestinal ecology through the neuroendocrine system. Additionally, baseline changes in the gut microbiota differed among patients with depression who demonstrated varying treatment response. Currently, probiotics are an emerging treatment for depression; however, the efficacy of modulating the gut microbiota in the treatment of depression remains uncertain. Additionally, the mechanisms by which changes in the gut microbiota affect treatment response in patients with depression remain unclear. In this review, we aimed to summarize the differences in the baseline gut microbiota between the remission and non-remission groups after antidepressant therapy. Additionally, we summarized the possible mechanisms that may contribute to antidepressant resistance through the effects of the gut microbiome on the immune and nervous systems, various enzymes, bioaccumulation, and blood-brain barrier, and provide a basis for treating depression by targeting the gut microbiota.

Microbiome Metabolomic Analysis of the Anxiolytic Effect of Baihe Dihuang Decoction in a Rat Model of Chronic Restraint Stress

Purpose

The Baihe Dihuang decoction (BDD) is a representative traditional Chinese medicinal formula that has been used to treat anxiety disorders for thousands of years. This study aimed to reveal mechanisms of anxiolytic effects of BDD with multidimensional omics.

Methods

First, 28-day chronic restraint stress (CRS) was used to create a rat model of anxiety, and the open field test and elevated plus maze were used to assess anxiety-like behavior. Enzyme-linked immunosorbent assay (ELISA), hematoxylin-eosin staining, and immunofluorescence staining were used to evaluate inflammatory response. Besides, 16S rRNA gene sequencing assessed fecal microbiota composition and differential microbiota. Non-targeted metabolomics analysis of feces was performed to determine fecal biomarkers, and targeted metabolomics was used to observe the levels of hippocampus neurotransmitters. Finally, Pearson correlation analysis was used to examine relationships among gut microbiota, fecal metabolites, and neurotransmitters.

Results

BDD significantly improved anxiety-like behaviors in CRS-induced rats and effectively ameliorated hippocampal neuronal damage and abnormal activation of hippocampal microglia. It also had a profound effect on the diversity of microbiota, as evidenced by significant changes in the abundance of 10 potential microbial biomarkers at the genus level. Additionally, BDD led to significant alterations in 18 fecal metabolites and 12 hippocampal neurotransmitters, with the majority of the metabolites implicated in amino acid metabolism pathways such as D-glutamine and D-glutamate, alanine, arginine and proline, and tryptophan metabolism. Furthermore, Pearson analysis showed a strong link among gut microbiota, metabolites, and neurotransmitters during anxiety and BDD treatment.

Conclusion

BDD can effectively improve anxiety-like behaviors by regulating the gut-brain axis, including gut microbiota and metabolite modification, suppression of hippocampal neuronal inflammation, and regulation of neurotransmitters.

Effects of Feather Hydrolysates Generated by Probiotic Bacillus licheniformis WHU on Gut Microbiota of Broiler and Common carp

Due to the ever-increasing demand for meat, it has become necessary to identify cheap and sustainable sources of protein for animal feed. Feathers are the major byproduct of poultry industry, which are rich in hard-to-degrade keratin protein. Previously we found that intact feathers can be digested into free amino acids, short peptides, and nano-/micro-keratin particles by the strain Bacillus licheniformis WHU in water, and the resulting feather hydrolysates exhibit prebiotic effects on mice. To explore the potential utilization of feather hydrolysate in the feed industry, we investigated its effects on the gut microbiota of broilers and fish. Our results suggest that feather hydrolysates significantly decrease and increase the diversity of gut microbial communities in broilers and fish, respectively. The composition of the gut microbiota was markedly altered in both of the animals. The abundance of bacteria with potentially pathogenic phenotypes in the gut microbial community of the fish significantly decreased. Staphylococcus spp., Pseudomonas spp., Neisseria spp., Achromobacter spp. were significantly inhibited by the feather hydrolysates. In addition, feather hydrolysates significantly improved proteolytic activity in the guts of broilers and fish. In fish, the expression levels of ZO-1 and TGF-α significantly improved after administration of feather hydrolysates. The results presented here suggest that feather hydrolysates generated by B. licheniformis WHU could be an alternative protein source in aquaculture and could exert beneficial effects on fish.

Bioconversion of feather waste into bioactive nutrients in water by Bacillus licheniformis WHU

Feathers become hazardous pollutants when deposited directly into the environment. The rapid expansion of the poultry industry has significantly increased feather waste, necessitating the development of new ways to degrade and utilize feathers. This study investigated the ability of Bacillus licheniformis WHU to digest intact chicken feathers in water. The results indicated that yields of free amino acids, bioactive peptides, and keratin-derived nano-/micro-particles were improved in bacteria- versus purified keratinase-derived feather hydrolysate. Bacteria-derived feather hydrolysate supplementation induced health benefits in mice, including significantly increased intestinal villus height and zonula occludens-1 protein expression, as well as increased secretory immunoglobulin A levels in the intestinal mucosa and superoxide dismutase activity in serum. Additionally, feather hydrolysate supplementation modulated the mouse gut microbiota, reflected by increased relative abundance of probiotics such as Lactobacillus spp., decreased relative abundance of Proteobacteria at the phylum level and pathogens such as Staphylococcus spp., and increased Bacteroidota/Firmicutes ratio. This study developed a simple, cost-effective method to degrade feathers by B. licheniformis WHU digestion, yielding a hydrolysate that can be directly used as a bioactive nutrient resource. The study findings have applications in the livestock, poultry, and aquaculture industries, which have high demands for cheap protein. KEY POINTS: • Bacillus licheniformis could degrade intact feather in water. • The resulting feather hydrolysate shows prebiotic effects on mouse.

Use of non-canonical amino acids in genetic code expansion-based therapeutics: Effects on mouse gut microbiota

Vaccines and cell therapeutics based on genetic code expansion are emerging. A crucial step in these therapeutic technologies is the oral administration of non-canonical amino acids (ncAAs) to control pathogen growth and therapeutic protein levels in vivo. Investigating the toxicity effects of ncAAs can help identify more suitable candidates for developing genetic code expansion-based vaccines and cell therapeutics. In this study, we determined the effects of three ncAAs, namely, 4-acetyl-phenylalanine (pAcF), 4-iodo-phenylalanine (pIoF), and 4-methoxy-phenylalanine (pMeoF), commonly used in genetic code expansion-based vaccines and cell therapeutics, on the main organs, serum biochemical parameters, and gut microbiota in mice. We observed that pIoF and pMeoF significantly altered serum biochemical parameters to some extent. Moreover, the alterations in the mouse gut microbial composition were considerably greater after the oral administration of pIoF and pMeoF than after that of pAcF, compared with that in the control mice. These findings suggest that pAcF is more suitable than pIoF and pMeoF for application in genetic code expansion-based vaccines and cell therapeutics as it disturbs the physiological and gut microecological balance in mice to a lesser extent.

Interactions Between Antidepressants and Intestinal Microbiota

The microbiota-gut-brain axis has been shown to influence human health and diseases, including depression. The interactions between drugs and intestinal microbiota are complex and highly relevant to treat diseases. Studies have shown an interaction between antidepressants and intestinal microbiota. Antidepressants may alter the abundance and composition of intestinal microbiota, which are closely related to the treatment outcomes of depression. Intestinal microbiota can influence the metabolism of antidepressants to change their availability (e.g., tryptophan can be metabolized to kynurenine by intestinal microbiota) and regulate their absorption by affecting intestinal permeability. In addition, the permeability of the blood-brain barrier can be altered by intestinal microbiota, influencing antidepressants to reach the central nervous system. Bioaccumulation is also a type of drug-microbiota interaction, which means bacteria accumulate drugs without biotransformation. These findings imply that it is important to consider intestinal microbiota when evaluating antidepressant therapy regimens and that intestinal microbiota can be a potential target for depression treatment.

Promoting Effect and Potential Mechanism of Lactobacillus pentosus LPQ1-Produced Active Compounds on the Secretion of 5-Hydroxytryptophan

5-hydroxytryptophan (5-HTP) is an important substance thought to improve depression. It has been shown that Lactobacillus can promote the secretion of 5-HTP in the body and thus ameliorate depression-like behavior in mice. However, the mechanism by which Lactobacillus promotes the secretion of 5-HTP is unclear. In this study, we investigated the promoting effect and mechanism of Lactobacillus, isolated from Chinese fermented foods, on the secretion of 5-HTP. The results showed that Lactobacillus (L.) pentosus LPQ1 exhibited the strongest 5-HTP secretion-promoting effect ((9.44 ± 0.69)-fold), which was dependent on the mixture of compounds secreted by L. pentosus LPQ1 (termed SLPQ1). In addition, the results of the RNA sequencing (RNA-seq) and quantitative real-time polymerase chain reaction (qRT-PCR) analyses indicated that SLPQ1 alters the TNF and oxidative phosphorylation signaling pathways. Moreover, the SLPQ1 ultrafiltration fraction (>10 kDa) showed a similar 5-HTP promoting effect as SLPQ1. Furthermore, reverse-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) identified 29 compounds of >10 kDa in SLPQ1, including DUF488 domain-containing protein, BspA family leucine-rich repeat surface protein, and 30S ribosomal protein S5, which together accounted for up to 62.51%. This study reports new findings on the mechanism by which L. pentosus LPQ1 promotes 5-HTP production in some cell lines in vitro.

Nattokinase enhances the preventive effects of Escherichia coli Nissle 1917 on dextran sulfate sodium-induced colitis in mice

Nattokinase with excellent anti-thrombotic, anti-inflammatory, anti-tumor, and anti-hypertension properties has been used in the development of several healthcare products in many countries. The probiotic Escherichia coli Nissle 1917 (EcN) with anti-inflammatory effect is commonly used to treat inflammatory bowel disease. To determine whether nattokinase could enhance the therapeutic efficacy of EcN in colitis, a recombinant E. coli Nissle 1917 strain (EcNnatto) with nattokinase-expressing ability was successfully constructed, and the protective effect of the engineered strain on mice with experimental chronic colitis was investigated. Although both EcN and EcNnatto strains substantially alleviated the clinical symptoms and pathological abnormalities in colitis mice by regulating gut flora and maintaining intestinal barrier function, the EcNnatto strain was found to perform better than the control strain, based on a further increase in colon length and a downregulation in pro-inflammatory cytokines (IL-6 and TNF-α). Nattokinase expressed in EcN attenuated DSS-induced epithelial damage and restored the mucosal integrity by upregulating the levels of tight junction proteins, including ZO-1 and occludin. The expression level of Lgr5, a marker of intestinal stem cells, was also increased. Moreover, constitutively expressed nattokinase in EcN reversed the gut microbial richness and diversity in colitis mice. Based on our findings, nattokinase could strengthen the capacity of EcN to treat intestinal inflammation.