Rapid intestinal and systemic metabolic reprogramming in an immunosuppressed environment

The microbiome's influence on obesity: mechanisms and therapeutic potential

In 2023, the World Obesity Atlas Federation concluded that more than 50% of the world's population would be overweight or obese within the next 12 years. At the heart of this epidemic lies the gut microbiota, a complex ecosystem that profoundly influences obesity-related metabolic health. Its multifaced role encompasses energy harvesting, inflammation, satiety signaling, gut barrier function, gut-brain communication, and adipose tissue homeostasis. Recognizing the complexities of the cross-talk between host physiology and gut microbiota is crucial for developing cutting-edge, microbiome-targeted therapies to address the global obesity crisis and its alarming health and economic repercussions. This narrative review analyzed the current state of knowledge, illuminating emerging research areas and their implications for leveraging gut microbial manipulations as therapeutic strategies to prevent and treat obesity and related disorders in humans. By elucidating the complex relationship between gut microflora and obesity, we aim to contribute to the growing body of knowledge underpinning this critical field, potentially paving the way for novel interventions to combat the worldwide obesity epidemic.

Behavioral alterations in antibiotic-treated mice associated with gut microbiota dysbiosis: insights from 16S rRNA and metabolomics

The gut and brain interact through various metabolic and signaling pathways, each of which influences mental health. Gut dysbiosis caused by antibiotics is a well-known phenomenon that has serious implications for gut microbiota-brain interactions. Although antibiotics disrupt the gut microbiota's fundamental structure, the mechanisms that modulate the response and their impact on brain function are still unclear. It is imperative to comprehend and investigate crucial regulators and factors that play important roles. We aimed to study the effect of long-term antibiotic-induced disruption of gut microbiota, host metabolomes, and brain function and, particularly, to determine the basic interactions between them by treating the C57BL/6 mice with two different, most commonly used antibiotics, ciprofloxacin and amoxicillin. Anxiety-like behavior was confirmed by the elevated plus-maze test and open field test. Gut microbes and their metabolite profiles in fecal, serum, and brain samples were determined by 16S rRNA sequencing and untargeted metabolomics. In our study, long-term antibiotic treatment exerted anxiety-like effects. The fecal microbiota and metabolite status revealed that the top five genera found were Lactobacillus, Bacteroides, Akkermansia, Ruminococcus_gnavus_group, and unclassified norank_f_Muribaculaceae. The concentration of serotonin, L-Tyrosine, 5-Hydroxy-L-tryptophan, L-Glutamic acid, L-Glutamate, 5-Hydroxyindole acetic acid, and dopaminergic synapsis was comparatively low, while adenosine was high in antibiotic-treated mice. The KEGG enrichment analysis of serum and brain samples showed that amino acid metabolism pathways, such as tryptophan metabolism, threonine metabolism, serotonergic synapsis, methionine metabolism, and neuroactive ligand-receptor interaction, were significantly decreased in antibiotic-treated mice. Our study demonstrates that long-term antibiotic use induces gut dysbiosis and alters metabolic responses, leading to the dysregulation of brain signaling molecules and anxiety-like behavior. These findings highlight the complex interactions between gut microbiota and metabolic functions, providing new insights into the influence of microbial communities on gut-brain communication.

Microbiota and metabolomic profiling coupled with machine learning to identify biomarkers and drug targets in nasopharyngeal carcinoma

Background

Nasopharyngeal carcinoma (NPC) is a prevalent malignancy in certain regions, with radiotherapy as the standard treatment. However, resistance to radiotherapy remains a critical challenge, necessitating the identification of novel biomarkers and therapeutic targets. The tumor-associated microbiota and metabolites have emerged as potential modulators of radiotherapy outcomes.

Methods

This study included 22 NPC patients stratified into radiotherapy-responsive (R, n = 12) and radiotherapy-non-responsive (NR, n = 10) groups. Tumor tissue and fecal samples were subjected to 16S rRNA sequencing to profile microbiota composition and targeted metabolomics to quantify short-chain fatty acids (SCFAs). The XGBoost algorithm was applied to identify microbial taxa associated with radiotherapy response, and quantitative PCR (qPCR) was used to validate key findings. Statistical analyses were conducted to assess differences in microbial diversity, relative abundance, and metabolite levels between the groups.

Results

Significant differences in alpha diversity at the species level were observed between the R and NR groups. Bacteroides acidifaciens was enriched in the NR group, while Propionibacterium acnes and Clostridium magna were more abundant in the R group. Machine learning identified Acidosoma, Propionibacterium acnes, and Clostridium magna as key predictors of radiotherapy response. Metabolomic profiling revealed elevated acetate levels in the NR group, implicating its role in tumor growth and immune evasion. Validation via qPCR confirmed the differential abundance of these microbial taxa in both tumor tissue and fecal samples.

Discussion

Our findings highlight the interplay between microbiota and metabolite profiles in influencing radiotherapy outcomes in NPC. These results suggest that targeting the microbiota-metabolite axis may enhance radiotherapy efficacy in NPC.

The Long-Term Effect of Kidney Transplantation on the Serum Fatty Acid Profile

Background: Epidemiologic evidence has demonstrated the prevalence of metabolic disorders and increased cardiovascular risk related to lipid metabolism disorders in kidney transplant recipients. Therefore, it is of great importance to understand lipid alterations and to look for ways to reduce cardiovascular risk in this patient group. Methods: Our study included 25 patients with chronic kidney disease undergoing kidney transplantation (KTx). Three blood samples were taken from each patient: before KTx, 3 months after KTx and 6-12 months after KTx. A series of biochemical blood tests and a detailed analysis of the serum fatty acid profile were performed. Results: In our previous study, the effects of kidney transplantation on serum fatty acid (FA) profile 3 months after the procedure were investigated. The current study shows the longer-term (6-12 months) effects of the procedure on the serum FA profile. We found that although n-3 polyunsaturated FA levels started to decrease 3 months after surgery, they normalized over a longer period of time (6-12 months). Furthermore, we observed a strong decrease in ultra-long-chain FAs and an increase in odd-chain FAs over a longer time after kidney transplantation. All of the above FAs may have an important impact on human health, including inflammation, cardiovascular risk or cancer risk. Conclusions: The changes in serum FA profiles after kidney transplantation are a dynamic process and that more detailed studies could provide an accurate indication for supplementation with some FAs or diet modification.

Early Immunomodulatory Program Triggered by Protolerogenic Bifidobacterium pseudolongum Drives Cardiac Transplant Outcomes

BACKGROUND

Despite ongoing improvements to regimens preventing allograft rejection, most cardiac and other organ grafts eventually succumb to chronic vasculopathy, interstitial fibrosis, or endothelial changes, and eventually graft failure. The events leading to chronic rejection are still poorly understood and the gut microbiota is a known driving force in immune dysfunction. We previously showed that gut microbiota dysbiosis profoundly influences the outcome of vascularized cardiac allografts and subsequently identified biomarker species associated with these differential graft outcomes.

METHODS

In this study, we further detailed the multifaceted immunomodulatory properties of protolerogenic and proinflammatory bacterial species over time, using our clinically relevant model of allogenic heart transplantation.

RESULTS

In addition to tracing longitudinal changes in the recipient gut microbiome over time, we observed that Bifidobacterium pseudolongum induced an early anti-inflammatory phenotype within 7 d, whereas Desulfovibrio desulfuricans resulted in a proinflammatory phenotype, defined by alterations in leukocyte distribution and lymph node (LN) structure. Indeed, in vitro results showed that B pseudolongum and D desulfuricans acted directly on primary innate immune cells. However, by 40 d after treatment, these 2 bacterial strains were associated with mixed effects in their impact on LN architecture and immune cell composition and loss of colonization within gut microbiota, despite protection of allografts from inflammation with B pseudolongum treatment.

CONCLUSIONS

These dynamic effects suggest a critical role for early microbiota-triggered immunologic events such as innate immune cell engagement, T-cell differentiation, and LN architectural changes in the subsequent modulation of protolerant versus proinflammatory immune responses in organ transplant recipients.