The Gut-Liver Axis in the Control of Energy Metabolism and Food Intake in Animals

Effects of dietary metabolizable energy level on hepatic lipid metabolism and cecal microbiota in aged laying hens

Lipid metabolic capacity, feed utilization, and the diversity of gut microbiota are reduced in the late laying stage for laying hens. This experiment aimed to investigate the effects of different levels of dietary metabolizable energy (ME) on hepatic lipid metabolism and cecal microbiota in late laying hens. The 216 Peking Pink laying hens (57-wk-old) were randomly assigned to experimental diets of 11.56 (HM = high ME), 11.14 (MM = medium ME), or 10.72 (LM = low ME) MJ of ME/kg, with each dietary treatment containing 6 replicates per group and 12 chickens per replicate. The HM group showed higher triglyceride (TG), total cholesterol (T-CHO), and low-density lipoprotein cholesterol (LDL-C) concentrations in the liver compared with the LM group; second, the HM group showed higher TG concentration and the LM group showed lower T-CHO concentration compared with MM group; finally, the HM group showed a lower hepatic lipase (HL) activity compared with the MM and LM groups (P < 0.05). There was a significant difference in the microbial community structure of the cecum between the HM and MM groups (P < 0.05). The decrease of dietary ME level resulted in a gradual decrease relative abundance of Proteobacteria. At the genus level, beneficial bacteria were significantly enriched in the LM group compared to the MM group, including Faecalibacterium, Lactobacillus, and Bifidobacterium, (linear discriminant analysis [LDA] >2, P <0.05). In addition, at the species level, Lactobacillus crispatus, Parabacteroides gordonii, Blautia caecimuris, and Lactobacillus johnsonii were significantly enriched in the LM group (LDA>2, P < 0.05). The HM group had a higher abundance of Sutterella spp. compared to the LM group (LDA>2, P <0.05). In conclusion, this research suggests that the reduction in dietary energy level did not adversely affect glycolipid metabolism or low dietary ME (10.72 MJ/kg). The findings can be helpful for maintaining intestinal homeostasis and increasing benefit for gut microbiota in late laying hens.

Effects of a biotechnologically produced Pleurotus sapidus mycelium on gut microbiome, liver transcriptome and plasma metabolome of broilers

Submerged cultivation using low-value agro-industrial side streams allows large-scale and efficient production of fungal mycelia, which has a high nutritional value. As the dietary properties of fungal mycelia in poultry are largely unknown, the present study aimed to investigate the effect of feeding a Pleurotus sapidus (PSA) mycelium as a feed supplement on growth performance, composition of the cecal microbiota and several physiological traits including gut integrity, nutrient digestibility, liver lipids, liver transcriptome and plasma metabolome in broilers. 72 males, 1-day-old Cobb 500 broilers were randomly assigned to 3 different groups and fed 3 different adequate diets containing either 0% (PSA-0), 2.5% (PSA-2.5) and 5% (PSA-5.0) P. sapidus mycelium in a 3-phase feeding system for 35 d. Each group consisted of 6 cages (replicates) with 4 broilers/cage. Body weight gain, feed intake and feed:gain ratio and apparent ileal digestibility of crude protein, ether extract and amino acids were not different between groups. Metagenomic analysis of the cecal microbiota revealed no differences between groups, except that one α-diversity metric (Shannon index) and the abundance of 2 low-abundance bacterial taxa (Clostridia UCG 014, Eubacteriales) differed between groups (P < 0.05). Concentrations of total and individual short-chain fatty acids in the cecal digesta and concentrations of plasma lipopolysaccharide and mRNA levels of proinflammatory genes, tight-junction proteins, and mucins in the cecum mucosa did not differ between groups. None of the plasma metabolites analyzed using targeted-metabolomics differed across the groups. Hepatic transcript profiling revealed a total of 144 transcripts to be differentially expressed between group PSA-5.0 and group PSA-0 but none of these genes was regulated greater 2-fold. Considering either the lack of effects or the very weak effects of feeding the P. sapidus mycelium in the broilers it can be concluded that inclusion of a sustainably produced fungal mycelium in broiler diets at the expense of other feed components has no negative consequences on broilers´ performance and metabolism.

Isobutyramide and Slow-Release Urea as Substitutes for Soybean Meal in the Finishing Diet of Beef Cattle

Two experiments were conducted to investigate the effects of isobutyramide (IBA) and slow-release urea (SRU) as substitutes for soybean meal (SBM) in the finishing diet of beef cattle. The completely randomized design in vitro experiment with five treatments, i.e., control, 0.9% SRU group, 0.6% SRU + 0.3% IBA group (SRU-I), 0.3% SRU + 0.6% IBA group (IBA-S), 0.9% IBA group was conducted. The results showed that the IBA-S and IBA increased (p ≤ 0.05) substrate disappearance of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), total gas, and total volatile fatty acids (TVFA). The SRU group had the highest (p < 0.01) crude protein disappearance and ammonia nitrogen concentration, but the IBA contrarily decreased (p < 0.01) them compared with the control. Inclusion of IBA increased isobutyrate concentrations (p = 0.01) with the highest value for the IBA group. Then, an 84-day replicate 4 × 4 Latin square design with 8 Angus steers and four treatments, i.e., control, SRU, SRU-I, IBA-S was performed. The results showed that the treatments did not affect DM intake (p > 0.05) but tended (p = 0.09) to increase average daily gain. The inclusion of IBA increased (p < 0.05) the apparent digestibility of DM, organic matter, NDF, ADF, TVFA, and microbial crude protein with the highest values for the IBA-S group. The IBA-contained groups also increased (p ≤ 0.01) isobutyrate concentration, activities of carboxymethyl cellulase and xylanase, and the relative abundance of Butyrivibrio fibrisolvens with the highest values for the IBA-S group. The SRU had no effect on animal growth and nutrient apparent digestibility. In conclusion, IBA was developed as a new substitute for SBM in the finishing diet of beef cattle, and the optimal strategy was the isonitrogenous substitution of SBM with 0.3% SRU and 0.6% IBA of the diet.

Investigation of the hypoglycemic mechanism of the ShenQi compound formula through metabonomics and 16S rRNA sequencing

Introduction: Herbal formulations are renowned for their complex biological activities, acting on multiple targets and pathways, as evidenced by in vitro studies. However, the hypoglycemic effect and underlying mechanisms of Shenqi Compound (SQ), a traditional Chinese herbal formula, remain elusive. This study aimed to elucidate the hypoglycemic effects of SQ and explore its mechanisms of action, focusing on intestinal flora and metabolomics. Methods: A Type 2 diabetes mellitus (T2DM) rat model was established through a high-fat diet, followed by variable glucose and insulin injections to mimic the fluctuating glycemic conditions seen in diabetes. Results: An eight-week regimen of SQ significantly mitigated hyperglycemia, inflammation, and insulin resistance in these rats. Notably, SQ beneficially modulated the gut microbiota by increasing populations of beneficial bacteria, such as Lachnospiraceae_NK4A136_group and Akkermansia, while reducing and inhibiting harmful strains such as Ruminococcus and Phascolarctobacterium. Metabolomics analyses revealed that SQ intervention corrected disturbances in Testosterone enanthate and Glycerophospholipid metabolism. Discussion: Our findings highlight the hypoglycemic potential of SQ and its mechanisms via modulation of the gut microbiota and metabolic pathways, offering a theoretical foundation for the use of herbal medicine in diabetes management.

Echinacea purpurea polysaccharide intervene in hepatocellular carcinoma via modulation of gut microbiota to inhibit TLR4/NF-κB pathway

Echinacea purpurea polysaccharide (EPP) exhibit various pharmacological activities, including immunomodulatory, anti-inflammatory, and anti-tumor effects. In this study, we investigated the potential mechanism of EPP intervention in hepatocellular carcinoma (HCC). The results demonstrated that EPP effectively mitigated liver injury caused by HCC, inhibited the proliferation of HCC, and induced apoptosis. Following EPP intervention, there was a significant increase in propionic acid and butyric acid-producing gut microbiota such as Coprococcus, Clostridium and Roseburia, leading to enhanced expression of intestinal tight junction proteins and the repair of the intestinal barrier. This controls lipopolysaccharide (LPS) leakage, which in turn inhibits the TLR4/NF-κB pathway and reduces the expression of inflammatory factors such as IL-6, as well as migration factors like MMP-2. Metabolomics revealed the downregulation of pyrimidine metabolism and nucleotide metabolism, along with the upregulation of butyrate metabolism in tumor cells. This study demonstrated that EPP effectively regulated LPS leakage by modulating gut microbes, and this modulation influenced the TLR4/NF-κB pathway, ultimately disrupting tumor cell survival induced by HCC in mice.

N-nitrosamines induced gender-dimorphic effects on infant rats at environmental levels

The safety of drinking water has always been a concern for people all over the world. N-nitrosamines (NAs), a kind of nitrogenous disinfection by-products (N-DBPs), are generally detected as a mixture in drinking water at home and abroad. Studies have shown that individual NAs posed strong carcinogenicity at high concentrations. However, health risks of NAs at environmental levels (concentrations in drinking water) are still unclear. Therefore, the potential health risks of environmentally relevant NAs exposure in drinking water needs to be conducted. In this study, blood biochemical analysis and metabolomics based on nuclear magnetic resonance (NMR) were performed to comprehensively investigate NAs induced metabolic disturbance in infant rats at environmental levels. Results of blood biochemical indices analysis indicated that AST in the serum of male rats in NAs-treated group exhibited a significant gender-specific difference. Multivariate statistics showed that two and eight significantly disturbed metabolic pathways were identified in the serum samples of NAs-treated male and female rats, respectively. In the urine samples of NAs-treated female rats, glycine, serine, and threonine metabolism pathway was significantly disturbed; while three significantly disturbed metabolic pathways were found in the urine of NAs-treated male rats. Finally, results of spearman correlation coefficients suggested that the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota (data derived from our published paper). Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management. ENVIRONMENTAL IMPLICATION: N-nitrosamines (NAs) are a kind of nitrogenous disinfection by-products (N-DBPs) generated during drinking water disinfection processes. Herein, health risks of NAs at environmental levels (concentrations in drinking water) are investigated using blood biochemical analysis and nuclear magnetic resonance (NMR)-based metabolomics. Results confirmed NAs induced gender-specific on the metabolism in rat and the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota. Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management.

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.

Traditional Chinese Medicine formula Dai-Zong-Fang alleviating hepatic steatosis in db/db mice via gut microbiota modulation

Introduction: Hepatic steatosis is a hepatic pathological change closely associated with metabolic disorders, commonly observed in various metabolic diseases such as metabolic syndrome (MetS), with a high global prevalence. Dai-Zong-Fang (DZF), a traditional Chinese herbal formula, is widely used in clinical treatment for MetS, exhibiting multifaceted effects in reducing obesity and regulating blood glucose and lipids. This study aims to explore the mechanism by which DZF modulates the gut microbiota and reduces hepatic steatosis based on the gut-liver axis. Methods: This study utilized db/db mice as a disease model for drug intervention. Body weight and fasting blood glucose were monitored. Serum lipid and transaminase levels were measured. Insulin tolerance test was conducted to assess insulin sensitivity. Hematoxylin and eosin (HE) staining was employed to observe morphological changes in the liver and intestine. The degree of hepatic steatosis was evaluated through Oil Red O staining and hepatic lipid determination. Changes in gut microbiota were assessed using 16S rRNA gene sequencing. Serum lipopolysaccharide (LPS) levels were measured by ELISA. The expression levels of intestinal tight junction proteins, intestinal lipid absorption-related proteins, and key proteins in hepatic lipid metabolism were examined through Western blot and RT-qPCR. Results: After DZF intervention, there was a decrease in body weight, alleviation of glucose and lipid metabolism disorders, reduction in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, and mitigation of insulin resistance in mice. DZF significantly modulated the diversity of the gut microbiota, with a notable increase in the abundance of the Bacteroidetes phylum. PICRUSt indicated that DZF influenced various functions in gut microbiota, including carbohydrate and amino acid metabolism. Following DZF intervention, serum LPS levels decreased, intestinal pathological damage was reduced, and the expression of intestinal tight junction protein occludin was increased, while the expression of intestinal lipid absorption-related proteins cluster of differentiation 36 (CD36) and apolipoprotein B48 (ApoB48) were decreased. In the liver, DZF intervention resulted in a reduction in hepatic steatosis and lipid droplets, accompanied by a decrease fatty acid synthase (FASN) and stearoyl-CoA desaturase 1 (SCD1) and fatty acid transport protein 2 (FATP2). Conversely, there was an increase in the expression of the fatty acid oxidation-related enzyme carnitine palmitoyltransferase-1𝛂 (CPT-1𝛂). Conclusion: DZF can regulate the structure and function of the intestinal microbiota in db/db mice. This ameliorates intestinal barrier damage and the detrimental effects of endotoxemia on hepatic metabolism. DZF not only inhibits intestinal lipid absorption but also improves hepatic lipid metabolism from various aspects, including de novo lipogenesis, fatty acid uptake, and fatty acid oxidation. This suggests that DZF may act on the liver and intestine as target organs, exerting its effects by improving the intestinal microbiota and related barrier and lipid absorption functions, ultimately ameliorating hepatic steatosis and enhancing overall glucose and lipid metabolism.

Emerging nanotherapeutic strategies targeting gut-X axis against diseases

Gut microbiota can coordinate with different tissues and organs to maintain human health, which derives the concept of the gut-X axis. Conversely, the dysbiosis of gut microbiota leads to the occurrence and development of various diseases, such as neurological diseases, liver diseases, and even cancers. Therefore, the modulation of gut microbiota offers new opportunities in the field of medicines. Antibiotics, probiotics or other treatments might restore unbalanced gut microbiota, which effects do not match what people have expected. Recently, nanomedicines with the high targeting ability and reduced toxicity make them an appreciative choice for relieving disease through targeting gut-X axis. Considering this paradigm-setting trend, the current review summarizes the advancements in gut microbiota and its related nanomedicines. Specifically, this article introduces the immunological effects of gut microbiota, summarizes the gut-X axis-associated diseases, and highlights the nanotherapeutics-mediated treatment via remolding the gut-X axis. Moreover, this review also discusses the challenges in studies related to nanomedicines targeting the gut microbiota and offers the future perspective, thereby aiming at charting a course toward clinic.

Non-12α-Hydroxylated Bile Acids Improve Piglet Growth Performance by Improving Intestinal Flora, Promoting Intestinal Development and Bile Acid Synthesis

As an emulsifier and bioactive substance, bile acids (BAs) participate in the absorption of nutrients and in various physiological processes. The objective of this experiment was to investigate the effects of non-12α-hydroxylated BAs (including hyocholic acid, hyodeoxycholic acid and chenodeoxycholic acid, from now on referred to as NBAs) on growth performance, BAs metabolism and the intestinal flora of piglets. The experiment included four groups, with eight piglets per group. The four groups of pigs were fed 0, 60, 120 and 180 mg/kg of NBAs, respectively. The results show that adding NBAs significantly increased the final weight (FW), average daily feed intake (ADFI), average daily gain (ADG), and digestibility of crude fat (EE) and organic matter (OM) in piglets (p < 0.05). Adding NBAs significantly increased the villus height (VH) of the jejunum and ileum (p < 0.05). In addition, NBAs supplementation increased the content of urea nitrogen (BUN) and creatinine (CREA) as well as the ratio of urea nitrogen to creatinine (BUN/CREA) in serum (p < 0.05). Adding NBAs can affect the genes related to BAs enterohepatic circulation. Specifically, adding NBAs significantly decreased the relative mRNA abundance of FXR in the liver (p < 0.05), significantly increased the relative mRNA abundance of CYP27A1 (p < 0.05), and significantly increased the relative mRNA abundance of NTCP (p < 0.05). Adding NBAs also significantly decreased the relative mRNA abundance of FXR in the ileum (p < 0.05). In the full-length 16S rDNA sequencing analysis, ten biomarkers were found from the gate to the species level. NBAs mainly enriched Lactobacillus_Johnsonii and decreased the abundance of Streptococcus_alactolyticus. Short-chain fatty acids (SCFAs) content in the colon was significantly increased (p < 0.05). These results indicate that NBAs supplementation can improve the growth performance of piglets, promote the development of the bile acid replacement pathway and improve intestinal flora.

Effect of Hermetia illucens Fat, Compared with That of Soybean Oil and Palm Oil, on Hepatic Lipid Metabolism and Plasma Metabolome in Healthy Rats

Palm oil (PO) is currently the most widely used fat source for food production, but insect fat from Hermetia illucens larvae (HF) might be a suitable alternative fat source, because its production is less harmful to the environment. The present study investigated the effect of HF, as compared to PO and soybean oil (SO), on the hepatic lipid metabolism and the plasma metabolome of healthy rats, which were randomly assigned to three groups (n = 10 rats/group), and fed three different semi-synthetic diets containing either SO, PO, or HF as the main fat source for 4 weeks. Feed intake, body weight gain, liver and plasma lipid concentrations, and the hepatic mRNA levels of genes involved in lipid metabolism and inflammation did not differ between groups. Targeted plasma metabolomics revealed 294 out of 630 metabolites analyzed to be different between groups. Principal component analysis showed a clear separation of the plasma metabolomes of the SO group and the other two groups, but no separation of those of the PO and the HF groups. The present study shows that HF exerts no adverse metabolic effects in healthy rats, compared to PO or SO, indicating that HF is a safe alternative fat source to PO for food production.

Early Infiltration of Innate Immune Cells to the Liver Depletes HNF4α and Promotes Extrahepatic Carcinogenesis

Multiple studies have identified metabolic changes within the tumor and its microenvironment during carcinogenesis. Yet, the mechanisms by which tumors affect the host metabolism are unclear. We find that systemic inflammation induced by cancer leads to liver infiltration of myeloid cells at early extrahepatic carcinogenesis. The infiltrating immune cells via IL6-pSTAT3 immune-hepatocyte cross-talk cause the depletion of a master metabolic regulator, HNF4α, consequently leading to systemic metabolic changes that promote breast and pancreatic cancer proliferation and a worse outcome. Preserving HNF4α levels maintains liver metabolism and restricts carcinogenesis. Standard liver biochemical tests can identify early metabolic changes and predict patients' outcomes and weight loss. Thus, the tumor induces early metabolic changes in its macroenvironment with diagnostic and potentially therapeutic implications for the host.

SIGNIFICANCE

Cancer growth requires a permanent nutrient supply starting from early disease stages. We find that the tumor extends its effect to the host's liver to obtain nutrients and rewires the systemic and tissue-specific metabolism early during carcinogenesis. Preserving liver metabolism restricts tumor growth and improves cancer outcomes. This article is highlighted in the In This Issue feature, p. 1501.

β-Glucan alleviates mice with ulcerative colitis through interactions between gut microbes and amino acids metabolism

BACKGROUND

Food polysaccharide 1,3-β-d-glucan (OBG) has been shown to alleviate ulcerative colitis (UC) in a mouse model, but the underlying mechanisms remain unclear. Here, we aimed to investigate potential mechanisms involving interactions among gut microbiota, microbial metabolites and host metabolic function.

RESULTS

OBG alleviated colonic inflammation, barrier dysfunction and intestinal concentrations of short-chain fatty acids in mice with UC. In addition, the relative abundance of Muribaculaceae, Alistipes, Erysipelatoclostridium and Blautia increased, whereas the abundance of Proteus, Lachnospiraceae and Ruminococcus decreased within the gut microbiota upon OBG treatment. Kyoto Encyclopedia of Genes and Genomes analyses showed that intestinal enzymes altered upon OBG treatment were mainly enriched in sub-pathways of amino acid biosynthesis. Metabolomics analyses showed that l-tryptophan, l-tyrosine, l-phenylalanine and l-alanine increased, which is consistent with the predictive metabolism of gut microbiota. Correlation analysis and interaction networks highlighted gut microbiota (especially Lactobacillus, Parabacteroides, Proteus and Blautia), metabolites (especially l-phenylalanine, l-tryptophan, l-tyrosine and acetic acid) and metabolism (phenylalanine, tyrosine and tryptophan biosynthesis) that may be key targets of OBG.

CONCLUSION

OBG is beneficial to the gut microecological balance in mice with colitis, mainly becaue of its impact on the interactions between gut microbes and amino acids metabolism (especially tyrosine and tryptophan metabolism). © 2022 Society of Chemical Industry.

A new strategy to alleviate the obesity induced by endocrine disruptors-A unique lysine metabolic pathway of nanoselenium Siraitia grosvenorii to repair gut microbiota and resist obesity

Obesity caused by endocrine disruptors (EDCs) has become a hot topic threatening human health. Recently, Nanoselenium Siraitia grosvenorii (NSG) has been shown to have potential health-modulating uses. Based on the results of 16S rRNA sequencing and metabolomics analysis, NSG has the unique function of improving gut microbiota and inhibiting obesity. Specifically, NSG can enhance gut microbiota diversity and change their composition. A significant positive correlation exists between the liver change in lysine and the high-importance dominant species ([Ruminococcus]_gnavus, Alistipes_finegoldii, etc.). NSG metabolites analysis showed that the lysine level increased by 44.45% and showed a significantly negatively correlated with (TG, TC, Leptin, etc.). Significantly, NSG reduces the degradation of lysine metabolism in the liver and inhibits fatty acid β-oxidation. In addition, NSG decreased Acetyl-CoA levels by 24% and regulated the downregulation of TCA genes (CS, Ogdh, Fh1, and Mdh2) and the upregulation of ketone body production genes (BDH1). NSG may have a positive effect on obesity by reducing the participation of Acetyl-CoA in the TCA cycle pathway and enhancing the ketogenic conversion of Acetyl-CoA. In conclusion, the results of this study may provide a new dietary intervention strategy for preventing endocrine disruptor-induced obesity.

Effect of replacement of soybean oil by Hermetia illucens fat on performance, digestibility, cecal microbiome, liver transcriptome and liver and plasma lipidomes of broilers

BACKGROUND

In contrast to protein-rich insect meal, the feed potential of insect fat is generally less explored and knowledge about the suitability of insect fat as a fat source specifically in broiler diets is still limited. In view of this, the present study aimed to comprehensively investigate the effect of partial (50%) and complete replacement of soybean oil with insect fat from Hermetia illucens (HI) larvae in broiler diets on performance, fat digestibility, cecal microbiome, liver transcriptome and liver and plasma lipidomes. Thus, 100 male, 1-day-old Cobb 500 broilers were randomly assigned to three groups and fed three different diets with either 0 (group HI-0, n = 30), 2.5% (group HI-2.5, n = 35) or 5.0% (HI-5.0, n = 35) Hermetia illucens (HI) larvae fat for 35 d.

RESULTS

Body weight gain, final body weight, feed intake, and feed:gain ratio during the whole period and apparent ileal digestibility coefficient for ether extract were not different between groups. Cecal microbial diversity did not differ between groups and taxonomic analysis revealed differences in the abundance of only four low-abundance bacterial taxa among groups; the abundances of phylum Actinobacteriota, class Coriobacteriia, order Coriobacteriales and family Eggerthellaceae were lower in group HI-5.0 compared to group HI-2.5 (P < 0.05). Concentrations of total and individual short-chain fatty acids in the cecal digesta were not different between the three groups. Liver transcriptomics revealed a total of 55 and 25 transcripts to be differentially expressed between groups HI-5.0 vs. HI-0 and groups HI-2.5 vs. HI-0, respectively (P < 0.05). The concentrations of most lipid classes, with the exception of phosphatidylethanolamine, phosphatidylglycerol and lysophosphatidylcholine in the liver and cholesterylester and ceramide in plasma (P < 0.05), and of the sum of all lipid classes were not different between groups.

CONCLUSIONS

Partial and complete replacement of soybean oil with HI larvae fat in broiler diets had no effect on growth performance and only modest, but no adverse effects on the cecal microbiome and the metabolic health of broilers. This suggests that HI larvae fat can be used as an alternative fat source in broiler diets, thereby, making broiler production more sustainable.

Effects of in vitro digestion and fecal fermentation on physico-chemical properties and metabolic behavior of polysaccharides from Clitocybe squamulosa

The aim of this study was to establish a human digestion model in vitro to explore the degradation characteristics of a novel high-purity polysaccharide from Clitocybe squamulosa (CSFP2). The results showed that the content of reducing sugars (C_R ) of CSFP2 increased from 0.13 to 0.23 mg/mL, the molecular weight (Mw) of CSFP2 decreased significantly during the saliva-gastrointestinal digestion. The constituent monosaccharides of CSFP2, including galactose, glucose, and mannose, were stable during in vitro digestion, but their molar ratios were changed from 0.023: 0.737: 0.234 to 0.496: 0.478: 0.027. The surface of CSFP2 changes from a rough flaky structure to a scattered flocculent or rod-shaped structure after the gastrointestinal digestion. However, the apparent viscosity of CSFP2 was overall stable during in vitro digestion. Moreover, CSFP2 still maintains its strong antioxidant capacity after saliva-gastrointestinal digestion. The results showed that CSFP2 can be partially decomposed during digestion. Meanwhile, some physico-chemical properties of the fermentation broth containing CSFP2 changed significantly after gut microbiota fermentation. For example, the pH value (from 8.46 to 4.72) decreased significantly (p < 0.05) after 48 h of fermentation. the OD ₆₀₀ value increased first and then decreased (from 2.00 to 2.68 to 1.32) during 48-h fermentation. In addition, CSFP2 could also increase the amounts of short-chain fatty acids (SCFAs) (from 5.5 to 37.15 mmol/L) during fermentation (in particular, acetic acid, propionic acid, and butyric acid). Furthermore, the relative abundances of Bacteriodes, Bifidobacterium, Catenibacterium, Lachnospiraceae_NK4A136_group, Megasphaera, Prevotella, Megamonas, and Lactobacillus at genus level were markedly increased with the intervention of CSFP2. These results provided a theoretical basis for the further development of functional foods related to CSFP2.

Gas-Mediated Intestinal Microbiome Regulation Prompts the Methanol Extract of Schizonepetae Spica to Relieve Colitis

Intestinal dysbiosis plays an important role in the pathogenesis of colitis (UC). Schizonepetae Herba can achieve anti-inflammatory effects as a medicine and food homologous vegetable. Luteolin, eriodictyol, fisetin, and kaempferol are the main anti-inflammatory active compounds obtained through mass spectrometry from the methanol extract of Schizonepetae Spica (JJSM). JJSM intervention resulted in attenuated weight loss, high disease-activity-index score, colon length shortening and colonic pathological damage in DSS-induced colitis mice. Interestingly, hydrogen sulfide (H₂S) was inhibited remarkably, which is helpful to elucidate the relationship between active substance and intestinal flora. Furthermore, JJSM administration improved intestinal flora with down-regulating the abundance of harmful bacteria such as Clostridiales and Desulfovibrio and up-regulating the abundance of beneficial bacteria such as Muribaculaceae and Ligolactobacillus and enhanced the production of SCFAs. It is worth noticing that Desulfovibrio is related to the production of intestinal gas H₂S. The elevated levels of Desulfovibrio and H₂S will hasten the onset of colitis, which is a crucial risk factor for colitis. The results displayed that JJSM could considerably ameliorate colitis by rebuilding H₂S-related intestinal flora, which provides a new therapeutic strategy for Schizonepetae Spica to be utilized as a functional food and considered as an emerging candidate for intestinal inflammation.

Multi-omics reveals diet-induced metabolic disorders and liver inflammation via microbiota-gut-liver axis

The gut microbiota medicated gut-liver axis is vital for liver function and health. We aimed to explore the underlying molecular mechanism of diet-induced metabolic liver disorders via microbiota-gut-liver axis using multi-omics. Metataxonomics, metaproteomics, transcriptomics, and metabolomics were conducted on liver tissue and biofluids (gastrointestinal contents and blood) to elucidate the microbial mechanism related to metabolic disorders and liver injury. The hepatic inflammation occurred based on histomorphology after feeding a long-term grain-based high-energy diet, and the serum biochemical parameters and proinflammatory cytokines were significantly activated. Metaproteomics analysis indicated that the high-energy diet reduced anti-infection, immunity, anti-oxidant functions, and increased cell death and damage of rumen microbiome. Ruminal Ruminococcus_2, Solobacterium, and Syntrophococcu and jejunal Pirellula were potential microbial markers of liver disorders. The high-energy diet promoted hepatic inflammatory response and cytokine/chemokine-mediated signaling pathways located in the core of the functional genomic network. The high-energy diet increased indoxyl sulfate and p-cresol sulfate and decreased triterpenoids in the liver that were the potential biomarkers associated with metabolic liver disorders. Integrated multi-omics analyses showed interactions among the rumen and jejunum microbiota, circulating metabolites, and liver gene expression, suggesting a systemic immune response and liver disorder that signals through the microbiota-gut-liver axis.

Coprophagy Prevention Affects the Reproductive Performance in New Zealand White Rabbits Is Mediated through Nox4-ROS-NFκB Pathway

Coprophagy is of great significance to the growth, development, and reproductive performance of rabbits. This study is aimed at exploring the effect of coprophagy on the reproductive performance of New Zealand white rabbits by coprophagy prevention (CP). The results showed that CP treatment significantly decreased the growth and development performance of female rabbits and the live birth rate of embryos. The results of blood biochemical indexes showed that CP treatment significantly increased the contents of serum ALB, ALP, and MDA, while serum SOD activity was significantly decreased. Transcriptome analysis showed that GO terms were mainly enriched in transport function and reproductive function after CP treatment. In addition, KEGG results showed that inflammation related signal pathways were activated and the expression level of genes related to tight junction proteins was downregulated by CP treatment. Concurrently, western blot further confirmed the results of KEGG. In short, fecal feeding is an important survival strategy for some small rodents, coprophagy prevention will affect the inflammatory level of the body, change the oxidative stress level of the body, and then activate NOX4-ROS-NF-κB pathway, increase the expression level of adhesion protein ICAM-1 and VCAM-1, lead to the damage of uterine epithelial barrier, and then affect the reproductive performance of rabbits.

Dietary sea buckthorn polysaccharide reduced lipid accumulation, alleviated inflammation and oxidative stress, and normalized imbalance of intestinal microbiota that was induced by high-fat diet in zebrafish Danio rerio

The purpose of this study was to explore the beneficial effects of sea buckthorn polysaccharide (SP) on lipid metabolism, liver, and intestinal health in zebrafish fed with high-fat diet (HFD). The zebrafish were fed with regular diet (RD), HFD, and HFD supplemented with 2 g/kg (HFD_2SP) and 4 g/kg (HFD_4SP) of SP, respectively. Growth, serum biochemistry, histopathology, expression of genes involved in lipid metabolism, inflammation, oxidative stress and tight junction, and changes in intestinal microbiota were detected. Results showed that adding 2 and 4 g/kg of SP in the HFD significantly improved the survival rate of zebrafish; reduced the levels of serum triglyceride (TG), total cholesterol (TC), aspartate aminotransferase (AST), and alanine transaminase (ALT); and alleviated the lipid accumulation in the liver of zebrafish. Furthermore, SP significantly enhanced the antioxidant capacity of liver and intestine by up-regulating the expression of Nrf2 and Cu/Zn-SOD and alleviated liver and intestinal inflammation induced by HFD through up-regulating the expression of TGF-β1 and suppressing the expression of P38MAPK, IL-8, and IL-1β. Especially, dietary SP normalized intestinal microbiota imbalance caused by HFD and inhibited the proliferation of harmful bacteria, i.e., Mycobacterium, but promoted the proliferation of intestinal beneficial bacteria, i.e., Cetobacterium. In summary, 2 and 4 g/kg of dietary SP significantly reduced lipid accumulation, alleviated inflammation and oxidative stress, and normalized the imbalance of intestinal microbiota induced by HFD and consequently improved the survival rate of zebrafish.

Heat stress in pigs and broilers: role of gut dysbiosis in the impairment of the gut-liver axis and restoration of these effects by probiotics, prebiotics and synbiotics

Heat stress is one of the most challenging stressors for animal production due to high economic losses resulting from impaired animal’s productivity, health and welfare. Despite the fact that all farm animal species are susceptible to heat stress, birds and pigs are particularly sensitive to heat stress due to either lacking or non-functional sweat glands. Convincing evidence in the literature exists that gut dysbiosis, a term used to describe a perturbation of commensal gut microbiota, develops in broilers and pigs under heat stress. Owing to the protective role of commensal bacteria for the gut barrier, gut dysbiosis causes a disruption of the gut barrier leading to endotoxemia, which contributes to the typical characteristics of heat stressed broilers and growing and growing-finishing pigs, such as reduced feed intake, decreased growth and reduced lean carcass weight. A substantial number of studies have shown that feeding of probiotics, prebiotics and synbiotics is an efficacious strategy to protect broilers from heat stress-induced gut barrier disruption through altering the gut microbiota and promoting all decisive structural, biochemical, and immunological elements of the intestinal barrier. In most of the available studies in heat stressed broilers, the alterations of gut microbiota and improvements of gut barrier function induced by feeding of either probiotics, prebiotics or synbiotics were accompanied by an improved productivity, health and/or welfare when compared to non-supplemented broilers exposed to heat stress. These findings indicate that the restoration of gut homeostasis and function is a key target for dietary interventions aiming to provide at least partial protection of broilers from the detrimental impact of heat stress conditions. Despite the fact that the number of studies dealing with the same feeding strategy in heat stressed pigs is limited, the available few studies suggest that feeding of probiotics might also be a suitable approach to enhance productivity, health and welfare in pigs kept under heat stress conditions. 

Gut microbial response to host metabolic phenotypes

A large number of studies have proved that biological metabolic phenotypes exist objectively and are gradually recognized by humans. Gut microbes affect the host's metabolic phenotype. They directly or indirectly participate in host metabolism, physiology and immunity through changes in population structure, metabolite differences, signal transduction and gene expression. Obtaining comprehensive information and specific identification factors associated with gut microbiota and host metabolic phenotypes has become the focus of research in the field of gut microbes, and it has become possible to find new and effective ways to prevent or treat host metabolic diseases. In the future, precise treatment of gut microbes will become one of the new therapeutic strategies. This article reviews the content of gut microbes and carbohydrate, amino acid, lipid and nucleic acid metabolic phenotypes, including metabolic intermediates, mechanisms of action, latest research findings and treatment strategies, which will help to understand the relationship between gut microbes and host metabolic phenotypes and the current research status.

GLP-1 and GLP-2 Orchestrate Intestine Integrity, Gut Microbiota, and Immune System Crosstalk

The intestine represents the body’s largest interface between internal organs and external environments except for its nutrient and fluid absorption functions. It has the ability to sense numerous endogenous and exogenous signals from both apical and basolateral surfaces and respond through endocrine and neuronal signaling to maintain metabolic homeostasis and energy expenditure. The intestine also harbours the largest population of microbes that interact with the host to maintain human health and diseases. Furthermore, the gut is known as the largest endocrine gland, secreting over 100 peptides and other molecules that act as signaling molecules to regulate human nutrition and physiology. Among these gut-derived hormones, glucagon-like peptide 1 (GLP-1) and -2 have received the most attention due to their critical role in intestinal function and food absorption as well as their application as key drug targets. In this review, we highlight the current state of the literature that has brought into light the importance of GLP-1 and GLP-2 in orchestrating intestine–microbiota–immune system crosstalk to maintain intestinal barrier integrity, inflammation, and metabolic homeostasis.

Isinglass Polysaccharides Regulate Intestinal-Barrier Function and Alleviate Obesity in High-Fat Diet Mice through the HO-1/Nrf2 Pathway and Intestinal Microbiome Environment

Plant polysaccharide intervention has shown significant potential to combat obesity. However, studies on animal polysaccharides are indeed rare. The aim of this study was to investigate the potential functions of CIP (IL) on obesity, intestinal microflora dysbiosis, and the possible protection of intestinal barrier in mice fed with high-fat diet (HFD). Our results revealed that after 13 weeks, the HFD+L (high-fat diet + 25 mg/kg CIP) group showed significantly more weight loss and fat accumulation relative to the HFD+H (high-fat diet + 50 mg/kg CIP) group. Furthermore, CIP intervention modulated lipid metabolism and mRNA levels of inflammatory mediators in liver. Overall, CIP clearly improved the intestinal barrier in HFD-fed mice. Additionally, we observed that CIP intervention improved intestinal microbiota community richness and diversity in HFD-fed mice. The CIP intervention mice group showed a relatively low Firmicutes to Bacteroidetes ratio compared to the HFD group. This study concluded that CIP could be used as a functional food to prevent adipocyte accumulation, reduce systemic inflammation, and protect the intestinal barrier.

Integrated analysis of multi-tissues lipidome and gut microbiome reveals microbiota-induced shifts on lipid metabolism in pigs

Lipid metabolism is very important for meat quality in pigs. Accumulating evidence shows that gut microbiota can contribute to this physiological process. However, the gut microbiota that function in lipid metabolism and adipogenesis remains unclear. Here, we compared the characteristics of fat deposition and gut microbial community between Laiwu pigs and Duroc × (Landrace × Yorkshire) (DLY) pigs. Fecal microbiota transplantation (FMT) was performed to determine the possible impact of gut microbiota on lipid metabolism in pigs. An integrated analysis of the gut microbiome and lipidome of the small intestine, plasma, and liver was conducted to investigate the effects of FMT on host lipid metabolism. The comparative analysis of the gut microbiome showed higher abundance of Bacteroidetes (P = 0.0018) while lower abundance of Firmicutes (P = 0.012) in Laiwu pigs, and the microbial composition can be transferred from Laiwu pigs into DLY pigs. Transmission electron microscope and Oil red-O staining were performed to analyze the effects of FMT on lipid deposition in liver, the main target organ for lipid metabolism. The results showed that FMT significantly increased the number of lipid droplets (P = 0.0035) and lipid accumulation (P = 0.0026) in liver. Furthermore, integrated multi-tissues lipidome analysis demonstrated that the fatty acyls and glycerophospholipids were significantly increased (P < 0.01) in intestine and liver, while glycerolipids and fatty acyls were reduced (P < 0.01) in plasma. In the small intestine, FMT increased (P < 0.01) the relative abundance of polyketides and prenol lipids but reduced (P < 0.01) the saccharolipids. Correlation analysis revealed the potential interactions between microbiota and lipid metabolites. Together, our results indicated that the gut microbiota may regulate the lipid metabolism and enhance the accumulation of lipid droplets in the liver of pigs.

Matcha green tea targets the gut-liver axis to alleviate obesity and metabolic disorders induced by a high-fat diet

Obesity induced by a high-fat diet (HFD) is an increasing global health problem, leading to many metabolic syndromes. As the emerging food additive rich in tea polyphenols, theanine, caffeine, and so on, matcha green tea has gained more and more popularity for its outstanding potential in ameliorating metabolic disorders. This study investigated the composition and antioxidant activity of matcha green tea and further explored its effects on gut-liver axis homeostasis in an HFD-induced obese mouse model. Male (7-8 weeks old) C57BL/6J mice were divided into four groups with the following dietary supplementation for 8 weeks: a normal chow diet (NCD), a normal chow diet+1.0% matcha (NCM), a high-fat diet (HFD), and a high-fat diet+1.0% matcha (HFM). The results demonstrated that matcha green tea ameliorated the development of obesity, lipid accumulation, and hepatic steatosis induced by HFD. Subsequently, dietary matcha supplementation restored the alterations in fecal bile acid profile and gut microbial composition. Meanwhile, the levels of mRNA expression in hepatocytes demonstrated that matcha intervention made significant regulatory on the multiple metabolic pathways of hosts involved in glucose, lipid, and bile acid metabolism. These findings present new evidence for matcha green tea as an effective nutritional strategy to mitigate obesity and relevant metabolic disorders through the gut-liver axis.

Niclosamide Exposure at Environmentally Relevant Concentrations Efficaciously Inhibited the Growth and Disturbed the Liver-Gut Axis of Adult Male Zebrafish

In the current study, adult male zebrafish fed a normal diet (ND) or high-fat diet (HFD) were exposed to niclosamide (NIC) at environmentally relevant concentrations to reveal the accumulation and distribution in different tissues and evaluate the effects on liver-gut axis. Chemical analysis indicated that the liver bore a greater burden of NIC compared with the brain and gonads in adult zebrafish, and the HFD-fed fish bore greater burden in their liver and brain than those ND-fed fish. The indications from body weight, growth rate, body mass index, micro-CT images, biochemical and pathological changes confirmed that NIC can efficaciously curb weight gain and improve overloads of in plasma insulin and glucose in HFD-fed zebrafish. However, the potential effects on liver-gut axis in ND-fed zebrafish were also elucidated: NIC disturbed mitochondrial energy production, inhibited the glycemic and triacylglycerol biosynthesis but promoted triacylglycerol and free fatty acid catabolism, therefore reduced lipid accumulation in hepatocytes; NIC also impaired the physical barrier, evoked inflammatory and oxidative stress and led to microbiota dysbiosis in the intestine. There findings highlighted the necessity for evaluating its potential impacts on the health of wild animals as well as human beings upon long-term exposure.

Influence of the Gut Microbiome on Feed Intake of Farm Animals

With the advancement of microbiome research, the requirement to consider the intestinal microbiome as the “last organ” of an animal emerged. Through the production of metabolites and/or the stimulation of the host’s hormone and neurotransmitter synthesis, the gut microbiota can potentially affect the host’s eating behavior both long and short-term. Based on current evidence, the major mediators appear to be short-chain fatty acids (SCFA), peptide hormones such as peptide YY (PYY) and glucagon-like peptide-1 (GLP-1), as well as the amino acid tryptophan with the associated neurotransmitter serotonin, dopamine and γ-Aminobutyrate (GABA). The influence appears to extend into central neuronal networks and the expression of taste receptors. An interconnection of metabolic processes with mechanisms of taste sensation suggests that the gut microbiota may even influence the sensations of their host. This review provides a summary of the current status of microbiome research in farm animals with respect to general appetite regulation and microbiota-related observations made on the influence on feed intake. This is briefly contrasted with the existing findings from research with rodent models in order to identify future research needs. Increasing our understanding of appetite regulation could improve the management of feed intake, feed frustration and anorexia related to unhealthy conditions in farm animals.

Fucoidan Is Not Completely Dependent on Degradation to Fucose to Relieve Ulcerative Colitis

Recently, fucoidan has been proposed for use as a potential anti-inflammatory drug. The purpose of this study was to investigate the mechanism of fucoidan in the treatment of ulcerative colitis. We compared the anti-inflammatory effects of fucoidan and fucose induced by dextran sulfate sodium, and the effects of fucoidan and fucose on the gut microbiota of mice. Our results showed that low-dose fucoidan significantly improved weight loss, disease activity index scores, colonic shortening, colonic histopathological damage, intestinal fatty acid binding protein 2 levels, and the expression of Occludin, Claudin-4, and Claudin-1. However, both high-dose fucoidan and fucose did not perform as well as low-dose fucoidan as described above. In addition, 16S rDNA high-throughput sequencing showed that low-dose fucoidan significantly increased the abundance of Alloprevotella, and fucose significantly increased Ruminococcaceae, but neither significantly reversed the imbalance in the gut microbiota. Therefore, we inferred that the regulation of fucoidan on colitis has a unique and complex mechanism, and it is not completely dependent on degradation to fucose to relieve ulcerative colitis, nor is it achieved only by regulating the gut microbiota. The mechanism by which fucoidan treats colitis may also include reducing inflammatory cell infiltration and increasing intestinal barrier function.

Effects of Corn and Broken Rice Extrusion on the Feed Intake, Nutrient Digestibility, and Gut Microbiota of Weaned Piglets

Simple Summary

Extruded cereals are largely used in newly weaned piglet diets to increase nutrient digestibility and palatability. Our findings showed that corn and broken rice extrusion diets generated negative effects on average daily feed intake (−63.5 g/day, p = 0.054) and average daily gain (−60.6 g/d, p = 0.015) in weaned piglets. Decreased feed intake was associated with increased plasma levels of the gut-derived hormones, glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), which may have been attributed to increased microbiota pathogen abundance, including Sarcina, Clostridium_sensu_strictio_1, and Terrisporobacter, and decreased short-chain fatty acid-producing microbiota, such as Lactobaillaceae and Bifidobateriaceae. Our results showed that extruded cereals should be used cautiously when formulating diets for newly weaned piglets.

Abstract

In this study, we investigated the effects of corn and rice extrusion diets on feed intake, nutrient digestibility, and gut microbiota in weaned piglets. Animals were divided into four dietary groups and fed a controlled diet containing (1) 62.17% corn (CORN), 15% soybean, 10% extruded full-fat soybean, and 6% fishmeal (2) half the corn replaced by extruded corn (ECORN), (3) broken rice (RICE), and (4) extruded broken rice (ERICE) for 28 days. Rice supplementation increased dry matter total tract digestibility and gross energy. Extruded cereals generated a lower average daily feed intake (ADFI) at 15–28 and 1–28 days, decreased average daily growth (ADG) at 15–28 and 1–28 days, and a lowered body weight (BW) on day 28, regardless of cereal type. Dietary extruded cereals increased the appetite-regulating hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). Piglets fed extruded cereals displayed low short-chain fatty acid (SCFA) levels in plasma and low Lactobaillaceae and Bifidobateriaceae levels in feces, whereas a higher abundance of the potential pathogens Sarcina, Clostridium_sensu_strictio_1 and Terrisporobacter was observed. Piglets fed extruded cereals displayed significantly lower gas and SCFA levels during in vitro fermentation. Combined, 50% corn substituted with extruded corn or broken rice decreased piglet growth performance, possibly by altering their microbiota.

Feeding of cuticles from Tenebrio molitor larvae modulates the gut microbiota and attenuates hepatic steatosis in obese Zucker rats

Insect biomass obtained from large-scale mass-rearing of insect larvae has gained considerable attention in recent years as an alternative and sustainable source of food and feed. A byproduct from mass-rearing of insect larvae is the shed cuticles - the most external components of insects which are a relevant source of the polysaccharide chitin. While it has been shown that chitin modulates the gut microbiota and ameliorates lipid metabolic disorders in obese rodent models, feeding studies dealing with isolated insects' cuticles are completely lacking. Thus, the present study tested the hypothesis that dietary insects' cuticles modulate the gut microbiome and improve hepatic lipid metabolism in obese Zucker rats. To test this hypothesis, three groups of obese Zucker rats were fed a nutrient-adequate, semisynthetic basal diet which was supplemented with either 0% (group O), 1.5% (group O1.5) or 3.0% (group O3.0) Tenebrio molitor cuticles at the expense of cellulose. Oil red O-stained liver sections showed a marked lipid accumulation, but lipid accumulation was clearly less in group O3.0 than in groups O and O1.5. In line with this, hepatic lipid concentrations were 30% lower in group O3.0 than in group O (p < 0.05). No differences were observed across the obese groups regarding liver concentrations of methionine, S-adenosylmethionine and homocysteine. Analysis of cecal microbial community at the family level revealed that the relative abundances of Bifidobacteriaceae, Coriobacteriaceae Erysipelotrichaceae, Lactobacillaceae, Prevotellaceae, Sutterellaceae, unknown Deltaproteobacteria and unknown Firmicutes were higher and those of Anaeroplasmataceae, Desulfovibrionaceae, Eubacteriaceae, Ruminococcaceae, Saccharibacteria and unknown Clostridiales were lower in group O3.0 compared to group O (p < 0.05). Cecal digesta concentrations of total short-chain fatty acids, acetate and butyrate were higher in group O3.0 than in group O (p < 0.05). Targeted plasma metabolomics revealed 53 metabolites differing between groups, amongst which two indole metabolites, indole-3-propionic acid and 3-indoxylsulfate, were markedly elevated in group O3.0 compared to groups O1.5 and O. Regarding that increased abundances of bacteria of the Actinobacteria phylum and Lactobacillaceae family in the gut have been reported to be associated with antisteatotic, hepatoprotective and antiinflammatory effects, the pronounced increases of Bifidobacteriaceae and Coriobacteriaceae (both Actinobacteria), and of Lactobacillaceae in group O3.0 might have contributed to the amelioration of fatty liver.

Effect of polysaccharides from Tibetan turnip (Brassica rapa L.) on the gut microbiome in vitro fermentation and in vivo metabolism

Tibetan turnip ( Brassica rapa L. ) polysaccharide (TTP) is an active ingredient and has been studied for many years due to its biological effect. There are few studies on...

Combination of microbiome and metabolome to analyze the cross-cooperation mechanism of Echinacea purpurea polysaccharide with gut microbiota in vitro and in vivo

Echinacea purpurea polysaccharide (EPP) is a functional compound in Echinacea purpurea. At the present, it is generally recognized that plant polysaccharides can regulate the intestinal microecology, but there are few...

Agouti-related protein as the glucose signaling sensor in the central melanocortin circuits in regulating fish food intake

Agouti-related protein (AgRP) is a neuropeptide synthesized by AgRP/NPY neurons and transcribed as 132 amino acids in humans and 142 amino acids (AgRP1) in Japanese seabass (Lateolabrax maculatus) fish. AgRP neurons are activated by hormonal signals of energy deficits and inhibited by signals of energy surpluses and have been demonstrated to have the ability to sense the dynamics of blood glucose concentrations as the "glucose sensor" in mammals. It is widely recognized that AgRP is an endogenous antagonist of the melanocortin-3 and -4 receptors (MC3R and MC4R) in the hypothalamus, exhibiting potent orexigenic activity and control of energy homeostasis. Most fish, especially carnivorous fish, cannot make efficient use of carbohydrates. When carbohydrates like corn or wheat bran are added as energy sources, they often cause feeding inhibition and metabolic diseases. When fishmeal is replaced by plant protein, this does not completely eliminate carbs, limiting the utilization of carbohydrates and plant proteins in aquaculture. Our previous study showed that AgRP, and not neuropeptide Y (NPY) is the principal protein molecule that correlates well with feeding behavior in Japanese seabass from anorexia to adaptation. The Ghrelin/Leptin-mTOR-S6K1-NPY/AgRP/POMC feed intake regulatory pathway responds to the plant-oriented protein which contains glucose. However, its regulatory function and mechanism are still not clear. This review offers an integrative overview of how glucose signals converge on a molecular level in AgRP neurons of the arcuate nucleus of the hypothalamus. This is in order to control fish food intake and energy homeostasis.

Chronic in vitro fermentation and in vivo metabolism: Extracellular polysaccharides from Sporidiobolus pararoseus regulate the intestinal microbiome of humans and mice

The fungus Sporidiobolus pararoseus not only produces carotenoids, but also produces bioactive extracellular polysaccharides (SPP). However, the relationship between SPP and the metabolism of gut microbiome is unclear. The aim of this study was to investigate the mechanism of SPP regulating intestinal health in vivo and in vitro. Results showed that SPP are nondigestible polysaccharides after the digestion with simulated stomach and small intestinal juice in vitro. After SPP was cultured in an in vitro intestinal simulation system for seven days, the concentration of short-chain fatty acids (SCFAs) increased; the microbial diversity changed; the relative abundance of Bifidobacterium and Streptococcus increased; and that of Escherichia Shigella and Lachnospiraceae NK4A136 decreased. In addition, metabolism of SPP by the mice colonic microbiome showed SPP decreased the relative abundance of Firmicutes and Bacteroidota, while the relative abundance of Verrucomicrobiota, Desulfobacterota, and Actinobacteriota increased. Finally, predicted Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolism results also showed that SPP can enhance the metabolism of cofactors, vitamins, amino acids, starch, and sucrose. In conclusion, SPP can multiply the intestinal beneficial bacteria of humans and mice, promote the production of SCFAs and metabolism of amino acids, and promote intestinal health.

Comprehensive functional core microbiome comparison in genetically obese and lean hosts under the same environment

Our study provides an exhaustive comparison of the microbiome core functionalities (captured by 3,936 microbial gene abundances) between hosts with divergent genotypes for intramuscular lipid deposition. After 10 generations of divergent selection for intramuscular fat in rabbits and 4.14 phenotypic standard deviations (SD) of selection response, we applied a combination of compositional and multivariate statistical techniques to identify 122 cecum microbial genes with differential abundances between the lines (ranging from -0.75 to +0.73 SD). This work elucidates that microbial biosynthesis lipopolysaccharides, peptidoglycans, lipoproteins, mucin components, and NADH reductases, amongst others, are influenced by the host genetic determination for lipid accretion in muscle. We also differentiated between host-genetically influenced microbial mechanisms regulating lipid deposition in body or intramuscular reservoirs, with only 28 out of 122 MGs commonly contributing to both. Importantly, the results of this study are of relevant interest for the efficient development of strategies fighting obesity.

In-depth analysis of the mechanisms of aloe polysaccharides on mitigating subacute colitis in mice via microbiota informatics

Aloe polysaccharides (APs) are indigestible bioactive polysaccharides, while can be fermented by colonic microbiota. Although plant polysaccharides can alleviate subacute ulcerative colitis (SUC), the mechanisms APs regulated SUC via colonic microbiota have not been fully explored. Hence, to elucidate the complex interactions between the novel APs, colonic microbiota, SCFAs, and inflammation, the SUC mouse model and in-depth analysis were performed, including multiple bioinformatics analysis and structural equation modeling (SEM). After APs intervention, SCFAs and SCFAs-producing genus, including Akkermansia and Blautia, were increased in colon, and the colonic inflammation and barrier dysfunction were alleviated significantly in SUC mice. Spearman analysis found positive correlations between microbiota and SCFAs. PICRUSt2 and KEGG analysis revealed 6-pyruvoyltetra hydropterin synthase in folate biosynthesis metabolism pathway was activated, while phosphotransferase system was inhibited. SEM results further proved APs was beneficial to gut micro-ecological balance in mice via SCFAs metabolism and anti-inflammatory functions. Together, APs could be exploited to alleviate SUC as dietary therapeutics.

Effect of Tenebrio molitor larvae meal on the antioxidant status and stress response pathways in tissues of growing pigs

Insect meal (IM) produced from edible insects, such as Tenebrio molitor, has been recognised as a potentially suitable protein component in feeding rations for monogastric livestock. While several studies with broilers have shown that animal´s health is not negatively affected by IM, less is known with regard to the influence of IM on metabolism of pigs. The present study investigates whether IM from Tenebrio molitor larvae causes oxidative stress and activates oxidative stress-sensitive signalling pathways in key metabolic tissues of pigs. To address this question, male 5-week-old crossbred pigs were randomly assigned to three groups of 10 pigs each and fed nutrient-adequate, isonitrogenous diets either without (CON) or with 5% IM or 10% IM from Tenebrio molitor larvae for 4 weeks. Concentrations of thiobarbituric acid reactive substances, tocopherols and glutathione in liver, gastrocnemius muscle and/or plasma did not differ between groups. Activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD) in the liver and of GPX and SOD in gastrocnemius muscle were not different between groups, whereas the activity of CAT in skeletal muscle was increased in the two IM-fed groups compared to group CON (p < 0.05). The mRNA levels of most of the target genes of oxidative stress-sensitive signalling pathways, such as nuclear factor-κB, nuclear factor erythroid 2-related factor 2 and endoplasmic reticulum stress-induced unfolded protein response, in liver and gastrocnemius muscle did not differ between the three groups. The present study shows that feeding a diet containing adequate levels of antioxidants, such as vitamin E and selenium, and Tenebrio molitor larvae meal as a protein component neither causes oxidative stress nor activates oxidative stress-sensitive signalling pathways in key metabolic tissues of growing pigs. Based on these observations, IM from Tenebrio molitor larvae can be regarded as a safe source of protein in growing pigs.

Aloe polysaccharides ameliorate acute colitis in mice via Nrf2/HO-1 signaling pathway and short-chain fatty acids metabolism

Aloe polysaccharides (APs) are acetyl polysaccharides. It has been reported APs could protect mice from ulcerative colitis (UC), but the complex interactions between APs and the intestinal barrier were unclear. Here, we investigated the relationship between APs and UC, and determined the synergistic effects of Nrf2/HO-1 signaling pathway and short-chain fatty acids (SCFAs) metabolism on protecting intestinal barrier in acute UC mice. Results showed APs could scavenge free radicals in vitro. In vivo, APs had the antioxidant and anti-inflammatory effect both in serum and colon. Besides, the pathological results showed APs could alleviate colonic lesions. Furthermore, our study indicated treatment with APs effectively increased SCFAs production. The inhibition of acute UC in mice was correlated with the APs-mediated effects on improving the expression of ZO-1, occludin, Nrf2, HO-I, and NQO1. Thus, APs effectively promoted the intestinal barrier via Nrf2/HO-1 signaling pathway and SCFAs metabolism, effectively ameliorating acute colitis in mice.

Combination Treatment of Arazyme and Soy Leaf Extract Attenuates Hyperglycemia and Hepatic Steatosis in High-Fat Diet-Fed C57BL/6J Mice

Arazyme and extracts of soy leaves (ESLs) are used as ingredients for functional foods; however, their combined administration has not been studied. This study assessed the combined effect of Arazyme and ESLs in high-fat-diet (HFD)-induced obese C57BL/6J mice fed 2 mg/kg Arazyme, 50 mg/kg ESLs, or a combination of 2 mg/kg Arazyme and 50 mg/kg ESLs by oral gavage for 13 weeks. Individually, Arazyme and ESLs had no effect on the HFD-induced phenotypes. The combination of Arazyme and ESLs significantly suppressed body weight gain, improved glucose and insulin tolerance, and suppressed hepatic steatosis by reducing lipid synthesis and enhancing lipid utilization gene expression. Furthermore, the combination significantly reduced HFD-induced plasma bile acid reabsorption by suppressing bile acid transporter expression, including the ATP biding cassette subfamily B member 11 (Abcb11), solute carrier family 10 member 1 (Slc10a1), Slc10a2, Slc51a, and Slc51b in the liver and gut. Moreover, the combination of Arazyme and ESLs significantly prevented HFD-induced islet compensation in the pancreas. These results suggest that the incorporation of Arazyme combined with ESLs reduces HFD-induced body weight, hyperglycemia, and hepatic steatosis by regulating liver–gut bile acid circulation in HFD-fed mice. This combination can markedly reduce treatment doses and enhance their therapeutic effects, thereby reducing therapeutic healthcare costs.

The Microbiota and the Gut-Brain Axis in Controlling Food Intake and Energy Homeostasis

Obesity currently represents a major societal and health challenge worldwide. Its prevalence has reached epidemic proportions and trends continue to rise, reflecting the need for more effective preventive measures. Hypothalamic circuits that control energy homeostasis in response to food intake are interesting targets for body-weight management, for example, through interventions that reinforce the gut-to-brain nutrient signalling, whose malfunction contributes to obesity. Gut microbiota-diet interactions might interfere in nutrient sensing and signalling from the gut to the brain, where the information is processed to control energy homeostasis. This gut microbiota-brain crosstalk is mediated by metabolites, mainly short chain fatty acids, secondary bile acids or amino acids-derived metabolites and subcellular bacterial components. These activate gut-endocrine and/or neural-mediated pathways or pass to systemic circulation and then reach the brain. Feeding time and dietary composition are the main drivers of the gut microbiota structure and function. Therefore, aberrant feeding patterns or unhealthy diets might alter gut microbiota-diet interactions and modify nutrient availability and/or microbial ligands transmitting information from the gut to the brain in response to food intake, thus impairing energy homeostasis. Herein, we update the scientific evidence supporting that gut microbiota is a source of novel dietary and non-dietary biological products that may beneficially regulate gut-to-brain communication and, thus, improve metabolic health. Additionally, we evaluate how the feeding time and dietary composition modulate the gut microbiota and, thereby, the intraluminal availability of these biological products with potential effects on energy homeostasis. The review also identifies knowledge gaps and the advances required to clinically apply microbiome-based strategies to improve the gut-brain axis function and, thus, combat obesity.

Tandem mass tag-based proteomics for studying the effects of a biotechnologically produced oyster mushroom against hepatic steatosis in obese Zucker rats

Hepatic steatosis is a very common response to liver injury and often attributed to metabolic disorders. Prior studies have demonstrated the efficacy of a biotechnologically produced oyster mushroom (Pleurotus sajor-caju, PSC) in alleviating hepatic steatosis in obese Zucker rats. This study aims to elucidate molecular events underlying the anti-steatotic effects of PSC. Tandem mass tag (TMT) peptide labeling coupled with LC-MS/MS/MS was used to quantify and compare proteins in the livers of lean Zucker rats fed a control diet (LC), obese Zucker rats fed the same control diet (OC) and obese Zucker rats fed the control diet supplemented with 5% PSC (OPSC) for 4 weeks. Using this technique 3128 proteins could be quantified, out of which 108 were differentially abundant between the OPSC and OC group. Functional enrichment analysis of the up-regulated proteins showed that these proteins were mainly involved in metabolic processes, while the down-regulated proteins were involved in inflammatory processes. Results from proteomic analysis were successfully validated for two up-regulated (carbonic anhydrase 3, regucalcin) and two down-regulated (cadherin-17, ceruloplasmin) proteins by means of immunoblotting. SIGNIFICANCE: Valorization of low-grade agricultural waste by edible fungi, such as the mushroom Pleurotus sajor-caju (PSC), represents a promising strategy for the production of protein rich biomass since they boast of a unique enzyme system that has the ability to recover nutrients and energy from biodegradable waste. Herein, we describe the metabolic effects of PSC feeding using a combined quantitative proteomics and bioinformatics approach. In total, 108 proteins were identified to be regulated by PSC feeding in the liver of the obese rats. Complementary usage of a bioinformatics approach allowed us to decipher the mechanisms underlying the recently observed lipid-lowering and anti-inflammatory activity of PSC feeding in obese Zucker rats, namely a reduction of fatty acid synthesis, an improvement of hepatoprotective mechanisms and an enhancement of anti-inflammatory effects.

Olive Fruit Extracts Supplement Improve Antioxidant Capacity via Altering Colonic Microbiota Composition in Mice

Oxidative stress, one of the most common biological dysfunctions, is usually associated with pathological conditions and multiple diseases in humans and animals. Chinese olive fruit (Canarium album L.) extracts (OE) are natural plant extracts rich in polyphenols (such as hydroxytyrosol, HT) and with antioxidant, anti-hyperlipidemia, and anti-inflammatory potentials. This study was conducted to investigate the antioxidant capacity of OE supplementation and its related molecular mechanism in mice. Mice (25.46 ± 1.65 g) were treated with 100 mg/kg body weight (BW) OE or saline solution for 4 weeks, and then the antioxidant and anti-inflammatory capacities of mice were examined. The results showed that OE supplement significantly increased the serum antioxidative enzyme activities of total antioxidant activity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase and decreased the serum malondialdehyde (MDA) level, indicating that OE treatment enhanced the antioxidant capacity in mice. qPCR results showed that the transcriptional expression of antioxidant SOD1, CAT, Gpx1, and Gpx2 were significantly down-regulated in the small intestine (jejunum and ileum) after OE administration. Meanwhile, OE treatment significantly decreased the T-AOC and increased the MDA level in the small intestine. Furthermore, OE administration dramatically reduced the mRNA expression of pro-inflammatory cytokines (TNF-α and IL-1β), which confirmed its antioxidant and anti-inflammatory capacities with OE administration. Using amplicon sequencing technology, 16S rRNA sequencing results showed that OE supplement significantly increased the colonic Firmicutes/Bacteroidetes ratio, which also had a negative correlation with the serum MDA level and positively correlated with serum GSH-Px activity through Pearson correlation analysis. Besides that, Alloprevotella was negatively correlated with serum T-AOC. Colidextribacter was positively correlated with serum MDA and negatively correlated with serum T-AOC, SOD, and GSH-Px levels. In summary, this study showed that treatment with 100 mg/kg BW polyphenol-rich OE could alter colonic microbiota community, which was strongly associated with improved antioxidant capacity in mice.

Dietary Polyphenols to Combat Nonalcoholic Fatty Liver Disease via the Gut-Brain-Liver Axis: A Review of Possible Mechanisms

Polyphenols are a group of micronutrients widely existing in plant foods including fruits, vegetables, and teas that can improve nonalcoholic fatty liver disease (NAFLD). In this review, the existing knowledge of dietary polyphenols for the development of NAFLD regulated by intestinal microecology is discussed. Polyphenols can influence the vagal afferent pathway in the central and enteric nervous system to control NAFLD via gut-brain-liver cross-talk. The possible mechanisms involve in the alteration of microbial community structure, effects of gut metabolites (short-chain fatty acids (SCFAs), bile acids (BAs), endogenous ethanol (EnEth)), and stimulation of gut-derived hormones (ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and leptin) based on the targets excavated from the gut-brain-liver axis. Consequently, the communication among the intestine, brain, and liver paves the way for new approaches to understand the underlying roles and mechanisms of dietary polyphenols in NAFLD pathology.

Dietary Influences on the Microbiota-Gut-Brain Axis

Over unimaginable expanses of evolutionary time, our gut microbiota have co-evolved with us, creating a symbiotic relationship in which each is utterly dependent upon the other. Far from confined to the recesses of the alimentary tract, our gut microbiota engage in complex and bi-directional communication with their host, which have far-reaching implications for overall health, wellbeing and normal physiological functioning. Amongst such communication streams, the microbiota–gut–brain axis predominates. Numerous complex mechanisms involve direct effects of the microbiota, or indirect effects through the release and absorption of the metabolic by-products of the gut microbiota. Proposed mechanisms implicate mitochondrial function, the hypothalamus–pituitary–adrenal axis, and autonomic, neuro-humeral, entero-endocrine and immunomodulatory pathways. Furthermore, dietary composition influences the relative abundance of gut microbiota species. Recent human-based data reveal that dietary effects on the gut microbiota can occur rapidly, and that our gut microbiota reflect our diet at any given time, although much inter-individual variation pertains. Although most studies on the effects of dietary macronutrients on the gut microbiota report on associations with relative changes in the abundance of particular species of bacteria, in broad terms, our modern-day animal-based Westernized diets are relatively high in fats and proteins and impoverished in fibres. This creates a perfect storm within the gut in which dysbiosis promotes localized inflammation, enhanced gut wall permeability, increased production of lipopolysaccharides, chronic endotoxemia and a resultant low-grade systemic inflammatory milieu, a harbinger of metabolic dysfunction and many modern-day chronic illnesses. Research should further focus on the colony effects of the gut microbiota on health and wellbeing, and dysbiotic effects on pathogenic pathways. Finally, we should revise our view of the gut microbiota from that of a seething mass of microbes to one of organ-status, on which our health and wellbeing utterly depends. Future guidelines on lifestyle strategies for wellbeing should integrate advice on the optimal establishment and maintenance of a healthy gut microbiota through dietary and other means. Although we are what we eat, perhaps more importantly, we are what our gut microbiota thrive on and they thrive on what we eat.

Dietary broccoli improves markers associated with glucose and lipid metabolism through modulation of gut microbiota in mice

OBJECTIVE

Broccoli is a "functional food" that contains bioactive compounds and phytochemicals that have beneficial health-promoting effects. This study aimed at investigating the effects of broccoli consumption on lipid and glucose metabolism and gut microbiota.

METHODS

Male C57BL/6J mice (7-8 wk old) were fed ad libitum with a normal diet supplemented with or without 10% (w/w) broccoli florets or broccoli stalks. Oral glucose tolerance tests were performed at week 15. After 17 wk, blood and tissues were collected. Serum parameters, histology, gene and protein expression, and intestinal microbiota composition were evaluated.

RESULTS

Stalk supplementation led to reductions in fasting glucose levels, serum insulin, and the homeostasis model assessment-insulin resistance (HOMA-IR) index. Liver enzymes improved in both experimental groups, and broccoli florets decreased total triacylglycerols. The stalks group had elevated fatty acid oxidation-related genes and proteins (AMPK, PPARα, and CPT1). Diverse microbiota populations were observed in both broccoli groups. Broccoli stalks were found to be richer in Akkermansia muciniphila, while broccoli florets reduced Mucispirillum schaedleri abundance and increased bacterial richness.

CONCLUSIONS

Long-term whole broccoli supplementation decreased inflammation, improved lipid parameters and insulin sensitivity, and altered the gut microbiome in mice. Our data provide new information regarding the potential benefits of broccoli stalks in metabolic parameters.