The signatures of liver metabolomics and gut microbiota in high-fat diet fed mice supplemented with rhododendrol

Phase-dependent hepatotoxicity of Aluminum oxide nanoparticles mediated through the intestinal microbiota

Aluminum oxide (Al2O3) nanoparticles (NPs) are extensively utilized in the food industry for applications such as food packaging, antimicrobial coatings, food processing equipment, and additives. Despite their widespread use, the mechanisms underlying Al2O3 NP-induced hepatotoxicity and the relationship between their physicochemical properties and toxicity remain inadequately understood. In this study, we explored the hepatotoxic effects of α-Al2O3 and γ-Al2O3 NPs in rats subjected to oral exposure for 28 days. Employing an integrated metabolomics and microbiome approach, we aimed to elucidate the potential mechanisms involved. Our findings revealed distinct hepatotoxic profiles for α-Al2O3 and γ-Al2O3 NPs, potentially mediated by differential interactions with the intestinal microbiome. α-Al2O3 NPs exhibited reduced hepatotoxicity, as evidenced by minimal liver oxidative stress, which may be associated with the upregulation of digestion-related intestinal flora such as Peptococcaceae and Romboutsia, potentially influencing Al2O3 accumulation in the liver. Conversely, γ-Al2O3 NPs demonstrated pronounced hepatotoxicity, characterized by liver histopathological changes and elevated levels of alanine aminotransferase, malondialdehyde, and glutathione. This increased toxicity was correlated with alterations in intestinal flora, including Ruminococcaceae and Exiguobacterium, which affected metabolites like L-phenylalanine and arachidonic acid, potentially contributing to hepatotoxicity. The results underscore the importance of the intestinal microbiome in mediating NP-induced toxicity and determining differences in toxicities of different NP phases. This study provides valuable insights into the differential toxicological impacts of Al2O3 NP phases, paving the way for safer nanomaterial design and application in the food industry.

Effects of short-term carbohydrate deprivation on glycolipid metabolism and hepatic lipid accumulation in mice

To investigate the effect of dietary carbohydrate levels on liver glycolipid metabolism, this study used C57BL/6J male mice receiving standard diet (CON), no-carbohydrate high-fat diet (NCD), and high-carbohydrate no-fat diet (HCD). One week after intervention, mice in the NCD group showed lower blood glucose, HbA1c and LDL-C as well as liver weight and liver index compared with the CON group. Further research found that the liver fat synthesis genes of mice in the NCD group were significantly down-regulated at the gene level, and histopathological sections showed that the livers of mice in the NCD group had less lipid accumulation. Furthermore, liver metabolomic analysis showed that primary bile acid levels and acylcarnitine levels in the liver of mice in the NCD group were significantly increased, and conversely, lysophosphatidylcholine and fatty acyl metabolites were significantly decreased. KEGG metabolic pathway analysis showed that metabolic pathways such as biosynthesis of unsaturated fatty acids and starch and sucrose metabolism were significantly inhibited in mice in the NCD group, while metabolic pathways such as primary bile acid biosynthesis, linoleic acid metabolism and glycerophospholipid metabolism were enhanced. Taken together, these results indicate that short-term carbohydrate deprivation improves blood glucose and lipid metabolism levels in mice; the molecular mechanism of action may involve inhibition of de novo lipogenesis and enhancement of bile acid metabolism.

Gut microbiota and metabolites as predictors of biologics response in inflammatory bowel disease: A comprehensive systematic review

Nonresponse to biologic agents in patients with inflammatory bowel disease (IBD) poses a significant public health burden, and the prediction of response to biologics offers valuable insights for IBD management. Given the pivotal role of gut microbiota and their endogenous metabolites in IBD, we conducted a systematic review to investigate the potential of fecal microbiota and mucosal microbiota and endogenous metabolomic markers as predictors for biotherapy response in IBD patients. A total of 38 studies were included in the review. Following anti-TNF-α treatment, the bacterial community characteristics of IBD patients exhibited a tendency to resemble those observed in healthy controls, indicating an improved clinical response. The levels of endogenous metabolites butyrate and deoxycholic acid were significantly associated with clinical remission following anti-TNF-α therapy. IBD patients who responded well to vedolizumab treatment had higher levels of specific bacteria that produce butyrate, along with increased levels of metabolites such as butyrate, branched-chain amino acids and acetamide following vedolizumab treatment. Crohn's disease patients who responded positively to ustekinumab treatment showed higher levels of Faecalibacterium and lower levels of Escherichia/Shigella. In conclusion, fecal microbiota and mucosal microbiota as well as their endogenous metabolites could provide a predictive tool for assessing the response of IBD patients to various biological agents and serve as a valuable reference for precise drug selection in clinical IBD patients.

Effects of short-term florfenicol exposure on the gene expression pattern, midgut microbiota, and metabolome in the lepidopteran model silkworm (Bombyx mori)

Florfenicol (FF), an alternative veterinary antibiotic for chloramphenicol, has been widely utilized in livestock breeding to prevent and treat bacterial diseases. However, the toxicological effects of FF have yet to be fully disclosed. The domesticated silkworm (Bombyx mori), a lepidopteran model, was selected to assess the toxicological effects of FF dietary exposure with multi-omics. The findings showed that high-dose (250 μg/L) FF exposure increased the whole cocoon weight. High-dose FF exposure affected the species richness and community diversity of the microbiota in the silkworm midgut. Biochemical processes and innate immunity were impacted by FF exposure. The KEGG pathways impacted by the midgut microbiota and their metabolites were compared, and several pathways were found to be related to the two ecosystems. In addition, the innate immunity and lipid metabolism pathways were impacted, and some of the differentially expressed genes were enriched in these pathways. These related pathways may involve crosstalk between the midgut microbiota shift, midgut biological functions, and global gene expression. Therefore, our study also advances the application of the silkworm larval model in assessing antibiotic metabolic toxicity and provides novel insights into the potential risks of FF.

Fat from Hermetia illucens Alters the Cecal Gut Microbiome and Lowers Hepatic Triglyceride Concentration in Comparison to Palm Oil in Obese Zucker Rats

BACKGROUND

Palm oil (PO) is the most widely utilized plant oil for food production. Owing to the great ecologic problems associated with PO production, sustainably produced fats, such as insect fat, might be a suitable alternative.

OBJECTIVES

The hypothesis was tested that fat from Hermetia illucens larvae (HF) compared with PO and soybean oil (SO) has no adverse effects on hepatic lipid metabolism, plasma metabolome, and cecal microbiome in obese Zucker rats.

METHODS

Thirty male obese Zucker rats were randomly assigned to 3 groups (SO, PO, HF; n = 10 rats/group) and fed 3 different semisynthetic diets containing either SO, PO, or HF as the main fat source for 4 wk. The effects were evaluated by measurement of liver and plasma lipid concentrations, liver transcriptomics, targeted plasma metabolomics, and cecal microbiomics.

RESULTS

Supplementation of HF reduced hepatic triglyceride concentration and messenger ribonucleic acid concentrations of selected genes involved in fatty acid and triglyceride synthesis in comparison to PO (P < 0.05). Pairwise comparison of the Simpson index and Jaccard index showed a higher cecal microbial α- and β-diversity in rats fed the HF diet than in rats fed the PO diet (P = 0.015 and P = 0.027), but no difference between rats fed the diets with SO or PO. Taxonomic analysis of the cecal microbial community revealed a lower abundance of Clostridium_sensu_stricto_1 and a higher abundance of Blautia, Mucispirillum, Anaerotruncus, Harryflintia, and Peptococcus in rats supplemented with HF than in rats supplemented with PO (P < 0.05).

CONCLUSIONS

HF, compared with PO, has liver lipid-lowering effects in obese Zucker rats, which may be caused by a shift in the gut microbial community. Thus, HF might serve as a sustainably produced fat alternative to PO for food production.

Glutamate and obesity - what is the link?

PURPOSE OF REVIEW

Many studies using metabolomics have tried to unravel the metabolic signature of obesity and understand the pathophysiology of this complex and heterogeneous disease. Circulating levels of the amino acid glutamate have been consistently associated with obesity and more specifically with measurements of abdominal fat accumulation. The purpose of this narrative review is to highlight recent studies documenting this association.

RECENT FINDINGS

Circulating glutamate concentrations have been positively correlated with measurements of central fat accumulation such as waist circumference and visceral adipose tissue area. Moreover, elevated glutamate levels have been linked to a higher prevalence of type 2 diabetes, cardiovascular diseases and nonalcoholic fatty liver disease. The association with adiposity is detected in early life, and genetic predisposition does not appear as a major driver. Glutamate levels reflect in vivo synthesis rather than dietary intake. However, interventions generating metabolic improvements such as incretin receptor agonist treatment or dietary improvements may reduce plasma levels of this amino acid.

SUMMARY

Recent findings confirm the consistent association between circulating glutamate and abdominal obesity and its cardiometabolic complications. The pathophysiological pathways underlying this phenomenon are still unclear. Furthermore, studies are needed to establish the usefulness of this analyte as a biomarker of abdominal obesity.