Bifidobacterium longum subsp. infantis (B. longum subsp. infantis) and Bifidobacterium adolescentis (B. adolescentis) play important roles in the guts of infants and adolescents, respectively. In this study, using a neonatal rat model, we compared the protective effects of these two bifidobacterial species against Salmonella infection. The results demonstrated that B. longum subsp. infantis was more effective than B. adolescentis in alleviating the severity of infection in newborn rats exposed to Salmonella enterica serovar Typhimurium strain SL1344. B. longum subsp. infantis attenuated intestinal inflammation and mucosal damage induced by Salmonella infection, as well as protecting intestinal nerves and intestinal barrier function through TLR4/MyD88 signalling. B. longum subsp. infantis also displayed the potential to modulate gut metabolites by promoting the biosynthesis of unsaturated fatty acids (arachidonic acid, eicosapentaenoic acid and α-linolenic acid) and purine metabolism (guanine, adenine, inosine and adenosine), thereby regulating metabolic disturbances. Additionally, the benefits of B. longum subsp. infantis were also observed in the liver, spleen and brain, improving nerve reflexes and suppressing hepatosplenomegaly. Overall, these findings provide novel insights into the prevention and treatment of gut-related diseases in newborns, highlighting the potentially significant role of B. longum subsp. infantis in clinical applications.

The decline in ovarian estrogen production is known to have detrimental health consequences and negatively affect the quality of life in menopausal women. Increasing estradiol levels is key to preventing disease in menopausal women. In this study, Lactobacillus gasseri CCFM1255 isolated from healthy infants was found to have a positive effect on estradiol production in ovariectomized rats. CYP19, the key enzyme catalysing the conversion of androgens into estrogens, was upregulated in adipose tissue upon CCFM1255 treatment. Untargeted metabolome analysis and targeted metabolite detection were used to identify the key metabolites altered by CCFM1255 treatment. CCFM1255 treatment significantly improved the serum concentration of glutamine (Gln). A significantly positive correlation was observed between serum Gln and estradiol concentrations. CCFM1255 treatment reshaped the structure of the gut microbiome, which was correlated with certain changes in serum metabolite concentrations. These results indicate that the provision of CCFM1255 as a dietary supplement may be an effective strategy to alleviate menopausal symptoms by increasing circulating estradiol.

Lactobacillus rhamnosus (Rh) and L. reuteri (Re) are well-known probiotic species in inflammatory bowel disease (IBD) research. The variations between these species’ efficacy against colitis, and their model of action in this regard, are intriguing and enable treatment to be individually tailored to patients. In this study, four strains each of Rh and Re were isolated from faecal samples and their draft genomes were sequenced. The anti-colitis activities of both strains involved various aspects of intestinal immune, physical, chemical, and biological barrier function. Strikingly, the tested strains exhibited considerable interspecies and intraspecies specificity in colitis amelioration. Rh strains significantly outperformed Re strains in terms of short-chain fatty acid synthesis. Nevertheless, Re strains were more effective than Rh strains in inhibiting production of inflammatory factors; promoting production of intestinal mucus, antimicrobial peptides, and tight junction proteins; and supporting the stem cell compartment. This accounts for the anti-colitis outcomes of Re strains being superior to those of Rh strains. In addition, the effective Rh and Re strains were found to express high concentrations of specific carbohydrate metabolism- and prophage-related genes, respectively. Taken together, the results of this study could assist researchers in developing effective therapies for IBD.

Gut microbiome is indispensable for maintaining normal brain function. Specifically, gut microbiota plays a causal role in sleep deprivation (SD)-induced cognitive impairment. In this study, neurobehavioral effects of the Bifidobacterium breve strain CCFM1025 were assessed in sleep-deprived mice. CCFM1025 improved the body weight and food and water intake of the mice. It also alleviated SD-induced cognitive behavioural abnormalities (in the novel object recognition test), but did not show beneficial effects on mood- and spatial memory-related behaviours. CCFM1025 significantly altered the gut microbial composition and genome function. Key microbial metabolites that may regulate sleep function were also identified, such as isovaleric acid and γ-aminobutyric acid in the gut and purine metabolites in the serum. Those metabolites may participate in gut–brain communication by acting on the striatal melatonin system, for example to increase melatonin levels, and by regulating the expression of circadian clock genes such as those encoding the adenosine A_2A receptor and period circadian regulator 1. Collectively, administration of probiotics alleviated cognitive impairment and circadian rhythm disturbance induced by SD via modulation of gut microbiome and its metabolites. These findings may help guide the treatment of insomnia or other sleep disorders via dietary strategies.

Lipid metabolism disorders commonly occur during menopause. Estrogen deficiency has been shown to lead to excessive energy intake and abnormal lipid metabolism in ovariectomized rats, resulting in obesity. Probiotics exhibit anti-obesity properties, and their underlying mechanism has been widely reported. In this study, we demonstrated the metabolic benefits of Lactobacillus plantarum CCFM1180 in suppressing appetite, controlling body weight, correcting obesity-induced abnormalities, enhancing liver lipid metabolism, and protecting liver function in estrogen-deficient rats. The mechanisms associated with the anti-obesity and antidyslipidemia effects of CCFM1180 on estrogen-deficient rats were clarified. The results showed that CCFM1180 dramatically reduced food intake by activating the expression of estrogen receptor alpha (ERα) and increasing the level of leptin in abdominal adipose tissue. These changes, combined with the increased butyrate concentration and recovered bile acid structure, helped enhance lipid metabolism. Additionally, CCFM1180 treatment was found to be safer than exogenous estrogen supplementation. Thus, L. plantarum CCFM1180 could be considered a new therapeutic strategy for preventing and alleviating menopausal lipid abnormalities.

The gut microbiota-brain axis has emerged as a novel target for Alzheimer's disease (AD), a neurodegenerative disease characterised by behavioural and cognitive impairment. However, most previous microbiome-based intervention studies have focused on single factors and yielded only modest cognitive improvements. Here, we proposed a multidomain intervention strategy that combined Bifidobacterium breve treatment with environmental enrichment (EE) training. In this study, we found that compared with EE or B. breve treatment alone, B. breve intervention combined with EE amplified its neuroprotective effects on AD mice, as reflected by improved cognition, inhibited neuroinflammation and enhanced synaptic function. Moreover, using microbiome and metabolome profiling, we found that the combination of B. breve and EE treatment restored AD-related gut microbiota dysbiosis and reversed microbial metabolite changes. Finally, by integrating behavioural and neurological data with metabolomic profiles, we revealed that the underlying mechanism may involve the modulation of microbiota-derived glutamine metabolism via gut-brain interactions. Collectively, combined B. breve intervention with EE treatment can alleviate AD-related cognitive impairment and improve brain function by regulating glutamine metabolism of the gut microbiome. Our findings provide a promising multidomain intervention strategy, with a combination of dietary microbiome-based and lifestyle-targeted interventions, to promote brain function and delay the progression of AD.