High-fat Diet Accelerates Intestinal Tumorigenesis Through Disrupting Intestinal Cell Membrane Integrity

The Effects of Food Nutrients and Bioactive Compounds on the Gut Microbiota: A Comprehensive Review

It is now widely recognized that gut microbiota plays a critical role not only in the development and progression of diseases, but also in its susceptibility to dietary patterns, food composition, and nutritional intake. In this comprehensive review, we have compiled the latest findings on the effects of food nutrients and bioactive compounds on the gut microbiota. The research indicates that certain components, such as unsaturated fatty acids, dietary fiber, and protein have a significant impact on the composition of bile salts and short-chain fatty acids through catabolic processes, thereby influencing the gut microbiota. Additionally, these compounds also have an effect on the ratio of Firmicutes to Bacteroides, as well as the abundance of specific species like Akkermansia muciniphila. The gut microbiota has been found to play a role in altering the absorption and metabolism of nutrients, bioactive compounds, and drugs, adding another layer of complexity to the interaction between food and gut microbiota, which often requires long-term adaptation to yield substantial outcomes. In conclusion, understanding the relationship between food compounds and gut microbiota can offer valuable insights into the potential therapeutic applications of food and dietary interventions in various diseases and health conditions.

Altered lipid metabolism in APC-driven colorectal cancer: the potential for therapeutic intervention

Altered lipid metabolism is a well-recognized feature of solid cancers, including colorectal cancer. In colorectal cancer, upregulation of lipid metabolism contributes to initiation, progression, and metastasis; thus, aberrant lipid metabolism contributes to a poor patient outcome. The inactivating mutation of APC, a vital tumor suppressor in the Wnt signaling pathway, is a key event that occurs early in the majority of colorectal cancer cases. The potential crosstalk between lipid metabolism and APC-driven colorectal cancer is poorly understood. This review collectively highlights and summarizes the limited understanding between mutations in APC and the upregulation of Wnt/beta-catenin signaling and lipid metabolism. The interconnection between APC inactivation and aberrant lipid metabolism activates Wnt/beta-catenin signaling which causes transcriptome, epigenetic, and microbiome changes to promote colorectal cancer initiation and progression. Furthermore, the downstream effects of this collaborative effort between aberrant Wnt/beta-catenin signaling and lipid metabolism are enhanced stemness, cellular proliferation, prooncogenic signaling, and survival. Understanding the mechanistic link between APC inactivation and alterations in lipid metabolism may foster identification of new therapeutic targets to enable development of more efficacious strategies for prevention and/or treatment of colorectal cancer.

N-Trimethylated chitosan coating white adipose tissue vascular-targeting oral nano-system for the enhanced anti-obesity effects of celastrol

Oral nanoparticles (NPs) are more suitable for obesity control compared to NPs administered intravenously, as their convenience increases patient compliance. Herein, we developed an oral nano-system to improve the anti-obesity efficacy of celastrol (Cel). The observed enhanced efficacy was mediated by zein core NPs decorated with adipose-homing peptides that were coated with N-trimethylated chitosan. The optimized Cel/AHP-NPs@TMC exhibited spherical morphology by TEM, as well as narrow size distribution (221.76 ± 6.73 nm) and adequate stability in a gastrointestinal environment. Based on the combined delivery advantages of AHP-NPs@TMC - i.e., improved cellular internalization within Caco-2 cells and enhanced white adipose tissue (WAT) vascular targeting - Cel/AHP-NPs@TMC significantly reduced the body weight, blood lipid levels, adipose inflammation, and WAT distribution in diet-induced obese mice without side-effects. In short, this study provides clear evidence that TMC-based oral NPs can effectively improve celastrol for obesity treatment.

Potential roles of gut microbial tryptophan metabolites in the complex pathogenesis of acne vulgaris

Acne vulgaris is a chronic inflammatory skin disease in which the influence of gut microbiota has been implicated but without clarification of mechanisms. Gut microbiota may exert such an influence via metabolites, particularly those of tryptophan. End metabolites of tryptophan activate receptors, including aryl hydrocarbon, G protein-coupled, and pregnane X receptors to stabilize the immune microenvironment and intestinal mucosal homeostasis. Any impact on the pathogenesis of acne vulgaris remains unclear. The current review collates recent advances concerning potential roles of tryptophan metabolism in mediating skin inflammation, follicular sebaceous gland function and intestinal permeability, all of which influence the pathogenesis of acne vulgaris. The aim was to improve understanding of the pathogenesis of acne vulgaris and to expose therapeutic opportunities.

Pathogenetic and clinical significance of the gut-liver microbiota axis

Today, nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) account for more than 50% of chronic liver diseases and cirrhosis in developed countries. The clinical significance of these pathologies lies in the formation of liver fibrosis and, therefore, in the increased risk of liver cirrhosis and hepatocellular carcinoma, which are life-threatening conditions. NAFLD is based on obesity and insulin resistance, whereas alcohol consumption is central to the etiopathogenesis of ALD. Recently, the role of the gut-liver microbiota axis in the genesis of NAFLD and ALD has also received increasing attention. Changes in qualitative and quantitative composition of intestinal microbiota and alterations of barrier function of intestinal mucosa can lead to entry of intraluminal antigens through portal vein system into the liver, inducing damage to hepatocytes and activation of proinflammatory processes. It is shown that in patients with CLD (NAFLD and ALD) there is an increase in  the permeability of the intestinal mucosa and dysbiotic changes of the intestinal microbiome. The role of the gut-liver microbiota axis is well described in the genesis of NAFLD and ALD. Chronic alcohol consumption leads to increased colonies of Gram-negative bacteria in the intestinal mucosa and, therefore, to the accumulation of endotoxins (lipopolysaccharide components of bacterial cell membranes). Acetaldehyde produced by ADH of the intestinal epithelium stimulates tyrosine phosphorylation of tight cell contacts, increasing intestinal mucosal permeability, which leads to translocation of endotoxins into the portal bloodstream. Obesity is a major risk factor for NAFLD, which is also associated with dysbiotic changes in the intestinal microbiome. Obese individuals have increased Firmicutes, decreased Bacteroidetes, mediated reduction of short-chain fatty acid synthesis and increased intestinal wall permeability due to disruption of intercellular dense contacts, which leads  to increased translocation of bacteria and endotoxins into the systemic bloodstream.

Functional gastrointestinal diseases: mechanisms of development and principles of multitarget therapy

Currently, functional dyspepsia (FD) and irritable bowel syndrome (IBS) are among the most common nosological  units in the structure of functional gastrointestinal  diseases in adults. An important problem of treatment of these diseases at the current stage of medicine is low efficiency of monotarget drugs, which is determined by multicomponent pathogenesis. Indeed, the currently available  methods of drug treatment of FD and IBS have suboptimal  efficacy, as illustrated  by recent meta-analyses demonstrating high rates of NNT (the average number of patients who need to be treated to achieve a certain favorable outcome). In addition, the frequent “overlap” of these diseases forces clinicians to prescribe several drugs with different pharmacological actions to the patient, which inevitably leads to a decrease in compliance. The optimal strategy for managing patients with FD and IBS is the tactics of multitarget drugs that act on several links in the pathogenesis of these pathologies and have a significant evidence base in the effectiveness and safety of use. STW 5 (Iberogast®), included  in the clinical  guidelines  of the Russian Gastroenterological Association on the diagnosis and treatment of patients with FD, published in 2017, has the above-mentioned characteristics, as well as the clinical guidelines of the Russian Gastroenterological Association in collaboration with the Russian Association of Coloproctologists on the diagnosis and treatment of IBS, published in 2021. The clinical effectiveness of Iberogast in the treatment of FD and IBS has been demonstrated in a number of randomized trials, the results of which showed high efficacy of the drug and its good tolerability.

A 3D-printable device allowing fast and reproducible longitudinal preparation of mouse intestines

Accurate and reproducible analysis of murine small and large intestinal tissue is key for preclinical models involving intestinal pathology. Currently, there is no easily accessible, standardized method that allows researchers of different skill levels to consistently dissect intestines in a time-efficient manner. Here, we describe the design and use of the 3D-printed "Mouse Intestinal Slicing Tool" (MIST), which can be used to longitudinally dissect murine intestines for further analysis. We benchmarked the MIST against a commonly used procedure involving scissors to make a longitudinal cut along the intestines. Use of the MIST halved the time per mouse to prepare the intestines and outperformed alternative methods in smoothness of the cutting edge and overall reproducibility. By sharing the plans for printing the MIST, we hope to contribute a uniformly applicable method for saving time and increasing consistency in studies of the mouse gastrointestinal tract.

Perturbation on gut microbiota impedes the onset of obesity in high fat diet-induced mice

High-calorie intake has become one of the most common causes of dietary obesity, which eventually develops into type 2 diabetes mellitus (T2DM). Microbiota, along with the length of the gastrointestinal tract, is related to metabolic disorders, but its shifts and following impact on metabolic disorders due to external perturbation are still unclear. To evaluate shifts of microbiota from the proximal to the distal intestine and their impact on metabolic disorders, we profiled jejunal and colonic microbiota with the perturbation using high salt (HS) and antibiotic-induced microbiota depletion (AIMD) in diet-induced obesity (DIO) mice and analyzed the association with parameters of both obesity and blood glucose. After ten weeks of feeding DIO mice with HS intake and AIMD, they failed to develop obesity. The DIO mice with HS intake had T2DM symptoms, whereas the AIMD DIO mice showed no significant difference in blood glucose parameters. We observed that the jejunal and colonic microbiota had shifted due to settled perturbation, and jejunal microbiota within a group were more dispersed than colonic microbiota. After further analyzing jejunal microbiota using quantified amplicon sequencing, we found that the absolute abundance of Colidextribacter (R = 0.695, p = 0.001) and Faecalibaculum (R = 0.631, p = 0.005) in the jejunum was positively correlated with the changes in BW and FBG levels. The predicted pathway of glucose and metabolism of other substances significantly changed between groups (p <0.05). We demonstrated that the onset of obesity and T2DM in DIO mice is impeded when the gut microbiota is perturbed; thus, this pathogenesis depends on the gut microbiota.

High-Fat, Western-Style Diet, Systemic Inflammation, and Gut Microbiota: A Narrative Review

The gut microbiota is responsible for recovering energy from food, providing hosts with vitamins, and providing a barrier function against exogenous pathogens. In addition, it is involved in maintaining the integrity of the intestinal epithelial barrier, crucial for the functional maturation of the gut immune system. The Western diet (WD)—an unhealthy diet with high consumption of fats—can be broadly characterized by overeating, frequent snacking, and a prolonged postprandial state. The term WD is commonly known and intuitively understood. However, the strict digital expression of nutrient ratios is not precisely defined. Based on the US data for 1908–1989, the calory intake available from fats increased from 32% to 45%. Besides the metabolic aspects (hyperinsulinemia, insulin resistance, dyslipidemia, sympathetic nervous system and renin-angiotensin system overstimulation, and oxidative stress), the consequences of excessive fat consumption (high-fat diet—HFD) comprise dysbiosis, gut barrier dysfunction, increased intestinal permeability, and leakage of toxic bacterial metabolites into the circulation. These can strongly contribute to the development of low-grade systemic inflammation. This narrative review highlights the most important recent advances linking HFD-driven dysbiosis and HFD-related inflammation, presents the pathomechanisms for these phenomena, and examines the possible causative relationship between pro-inflammatory status and gut microbiota changes.

High-fat diet-activated fatty acid oxidation mediates intestinal stemness and tumorigenicity

Obesity is an established risk factor for cancer in many tissues. In the mammalian intestine, a pro-obesity high-fat diet (HFD) promotes regeneration and tumorigenesis by enhancing intestinal stem cell (ISC) numbers, proliferation, and function. Although PPAR (peroxisome proliferator-activated receptor) nuclear receptor activity has been proposed to facilitate these effects, their exact role is unclear. Here we find that, in loss-of-function in vivo models, PPARα and PPARδ contribute to the HFD response in ISCs. Mechanistically, both PPARs do so by robustly inducing a downstream fatty acid oxidation (FAO) metabolic program. Pharmacologic and genetic disruption of CPT1A (the rate-controlling enzyme of mitochondrial FAO) blunts the HFD phenotype in ISCs. Furthermore, inhibition of CPT1A dampens the pro-tumorigenic consequences of a HFD on early tumor incidence and progression. These findings demonstrate that inhibition of a HFD-activated FAO program creates a therapeutic opportunity to counter the effects of a HFD on ISCs and intestinal tumorigenesis.

Differential protection by anthocyanin-rich bilberry extract and resveratrol against lipid micelle-induced oxidative stress and monolayer permeability in Caco-2 intestinal epithelial cells

Excess dietary fat, and associated bile acids, can impair intestinal barrier integrity, produce intestinal or systemic inflammation and promote tumorigenesis.

The inflammatory environment mediated by a high-fat diet inhibited the development of mammary glands and destroyed the tight junction in pregnant mice

Long-term intake of a high-fat diet seriously affects the health of pregnant women and leads to increased levels of inflammation in the mammary gland. Therefore, to further explore the effect of a high-fat diet on mammary gland development and the tight junction (TJ) during pregnancy, we placed mice into two groups: a high-fat diet group and a control group. We detected the expression of proteins related to fat synthesis in the mammary gland by western blotting. The results showed that a high-fat diet could lead to an increase in fat synthesis in the mammary gland. Then, the inflammatory levels and acinar cell morphology in the mammary gland were detected by ELISA and H&E staining. We also measured the levels of MAPK and NF-κB signal pathway-related proteins by western blotting. The results showed that a high-fat diet activated the MAPK and NF-κB signaling pathways and promoted the expression of inflammatory factors. Finally, the development of the mammary gland and the integrity of the TJ were determined by immunohistochemistry, immunofluorescence and western blotting. The results showed that a high-fat diet inhibited the development of the mammary gland and the expression of tight junction proteins (TJs). Our study showed that a high-fat diet could promote the expression of inflammatory factors by activating the MAPK and NF-κB signaling pathways and could reshape the microenvironment through extramammary inflammation. Finally, a high-fat diet inhibited the development of the mammary gland during pregnancy and destroyed the integrity of the TJ.

Probiotic strain Lactobacillus plantarum YYC-3 prevents colon cancer in mice by regulating the tumour microenvironment

The gut microbiota plays important roles in chronic inflammation and colon cancer. Lactobacillus is a gut-resident probiotic with benefits to host health. We recently identified Lactobacillus plantarum strain YYC-3 with strong inhibition against two colon cancer cell lines (HT-29 and Caco2). However, the inhibitory effect of YYC-3 against colon cancer in vivo has not been verified. Thus, in the present study, we explored the probiotic function of strain YYC-3 and its cell-free supernatant (YYCS) respectively in the APC^Min/+ mouse model of colon cancer during tumour development and growth, and the underlying anti-cancer mechanism. Treatment of both strain YYC-3 and the YYCS prevented the occurrence of colon tumours and mucosal damage in APC^Min/+ mice fed a high-fat diet, although YYC-3 had a stronger anti-cancer effect. The mechanism involved modulation of the immune system and downregulated expression of the inflammatory cytokines interleukin (IL)-6, IL-17 F, and IL-22, along with reduced infiltration of inflammatory cells. Moreover, YYC-3 suppressed activation of the NF-κB and Wnt signalling pathways, and restored the altered gut microbiota composition to closely match that of wild-type mice. These results lay a theoretical foundation for application of YYC-3 in colon cancer prevention.

Negative Effects of a High-Fat Diet on Intestinal Permeability: A Review

The intestinal tract is the largest barrier between a person and the environment. In this role, the intestinal tract is responsible not only for absorbing essential dietary nutrients, but also for protecting the host from a variety of ingested toxins and microbes. The intestinal barrier system is composed of a mucus layer, intestinal epithelial cells (IECs), tight junctions (TJs), immune cells, and a gut microbiota, which are all susceptible to external factors such as dietary fats. When components of this barrier system are disrupted, intestinal permeability to luminal contents increases, which is implicated in intestinal pathologies such as inflammatory bowel disease, necrotizing enterocolitis, and celiac disease. Currently, there is mounting evidence that consumption of excess dietary fats can enhance intestinal permeability differentially. For example, dietary fat modulates the expression and distribution of TJs, stimulates a shift to barrier-disrupting hydrophobic bile acids, and even induces IEC oxidative stress and apoptosis. In addition, a high-fat diet (HFD) enhances intestinal permeability directly by stimulating proinflammatory signaling cascades and indirectly via increasing barrier-disrupting cytokines [TNFα, interleukin (IL) 1B, IL6, and interferon γ (IFNγ)] and decreasing barrier-forming cytokines (IL10, IL17, and IL22). Finally, an HFD negatively modulates the intestinal mucus composition and enriches the gut microflora with barrier-disrupting species. Although further research is necessary to understand the precise role HFDs play in intestinal permeability, current data suggest a stronger link between diet and intestinal disease than was first thought to exist. Therefore, this review seeks to highlight the various ways an HFD disrupts the gut barrier system and its many implications in human health.

PPARδ Mediates the Effect of Dietary Fat in Promoting Colorectal Cancer Metastasis

The nuclear hormone receptor peroxisome proliferator-activated receptor delta (PPARδ) is a ligand-dependent transcription factor involved in fatty acid metabolism, obesity, wound healing, inflammation, and cancer. Although PPARδ has been shown to promote intestinal adenoma formation and growth, the molecular mechanisms underlying the contribution of PPARδ to colorectal cancer remain unclear. Here, we demonstrate that activation of PPARδ induces expansion of colonic cancer stem cells (CSC) and promotes colorectal cancer liver metastasis by binding to the Nanog promoter and enhancing Nanog expression. Moreover, PPARδ mediated the effect of a high-fat diet in promoting liver metastasis and induction of colonic CSC expansion. Our findings uncover a novel role of dietary fats in colorectal cancer metastasis and reveal novel mechanisms underlying PPARδ-mediated induction of CSCs and those responsible for the contribution of dietary fats to colorectal cancer progression. These findings may provide a rationale for developing PPARδ antagonists to therapeutically target CSCs in colorectal cancer. SIGNIFICANCE: These findings show that PPARδ contributes to colorectal cancer metastasis by expanding the CSC population, indicating that antagonists that target PPARδ may be beneficial in treating colorectal cancer.

Chia flour (Salvia hispanica L.) did not improve the deleterious aspects of hyperlipidic diet ingestion on glucose metabolism, but worsened glycaemia in mice

Obesity is mainly caused by intake of a high-fat diet and sedentarism, and is considered a public health issue worldwide. Increased intestinal permeability may favour endotoxaemia generated by lipopolysaccharides, a substance present in the cell membrane of Gram-negative bacteria, and, consequently, an increase in systemic inflammation and metabolic diseases. In contrast (On the other hand), consumption of a healthy diet can help in the prevention and treatment of metabolic syndrome. In this way, chia seeds (Salvia hispanica L.), rich in polyunsaturated fatty acids, may present an anti-inflammatory role. In addition, chia is rich in antioxidants like caffeic and gallic acid and fiber. However, few studies have investigated the relationship between chia seeds, inflammatory mechanisms and intestinal permeability. Therefore, the aim of this study was to analyse the effects of chia administration on metabolism in obese mice. Swiss mice were fed a hyperlipidic diet either supplemented with or without 3% chia flour for 16 weeks. The results showed that supplementation could not reduce the deleterious effects of the lipid-rich diet in terms of body composition, glucose intolerance and activity of antioxidants enzymes in the liver. In addition, supplementation with chia in the control diet decreased the amount of occludin in the intestinal colon. In conclusion, although chia did not improve metabolic parameters it seemed to restore the intestinal barriers integrity. The beneficial effects of chia seem to be dependent of the quantity used, since our data conflict with those in the literature; however, it is important to note that other studies, unlike our protocol, used chia in the form of seeds or oil, and not flour.

Can prebiotics assist in the management of cognition and weight gain in schizophrenia?

Schizophrenia is among the top half of the 25 leading causes of disabilities worldwide with a 10-20 year decrease in life expectancy. Ineffective pharmacotherapy in the management of cognitive deficits and weight gain are known to be significant contributors; therefore interventions that may mitigate one, or both, of these parameters would be highly beneficial. Manipulation of the gut microbiome using dietary supplements such as prebiotics may be one such intervention. Preclinical studies have shown that a 2-4 week dietary supplementation with a prebiotic has beneficial effects on learning and memory, and prevents pro-inflammatory signals that are detrimental to cognitive processes. Furthermore, prebiotics influence metabolism, and in obesity they increase the expression of anorexigenic gut hormones such as peptide tyrosine tyrosine, glucagon-like peptide 1 and leptin, as well as decrease levels of orexigenic hormones such as ghrelin. Despite compelling evidence for the pro-cognitive and neuroprotective effects of prebiotics in rodents, their ability to alleviate cognitive deficits or enhance cognition needs to be evaluated in humans. Here we suggest that important symptoms associated with schizophrenia, such as cognitive impairment and weight gain, may benefit from concurrent prebiotic therapy.

Abnormal Barrier Function in Gastrointestinal Disorders

There is increasing concern in identifying the mechanisms underlying the intimate control of the intestinal barrier, as deregulation of its function is strongly associated with digestive (organic and functional) and a number of non-digestive (schizophrenia, diabetes, sepsis, among others) disorders. The intestinal barrier is a complex and effective defensive functional system that operates to limit luminal antigen access to the internal milieu while maintaining nutrient and electrolyte absorption. Intestinal permeability to substances is mainly determined by the physicochemical properties of the barrier, with the epithelium, mucosal immunity, and neural activity playing a major role. In functional gastrointestinal disorders (FGIDs), the absence of structural or biochemical abnormalities that explain chronic symptoms is probably close to its end, as recent research is providing evidence of structural gut alterations, at least in certain subsets, mainly in functional dyspepsia (FD) and irritable bowel syndrome (IBS). These alterations are associated with increased permeability, which seems to reflect mucosal inflammation and neural activation. The participation of each anatomical and functional component of barrier function in homeostasis and intestinal dysfunction is described, with a special focus on FGIDs.