Derangement of intestinal epithelial cell monolayer by dietary cholesterol oxidation products

Implication of Oxysterols and Phytosterols in Aging and Human Diseases

Cholesterol is easily oxidized and can be transformed into numerous oxidation products, among which oxysterols. Phytosterols are plant sterols related to cholesterol. Both oxysterols and phytosterols can have an impact on human health and diseases.Cholesterol is a member of the sterol family that plays essential roles in biological processes, including cell membrane stability and myelin formation. Cholesterol can be metabolized into several molecules including bile acids, hormones, and oxysterols. On the other hand, phytosterols are plant-derived compounds structurally related to cholesterol, which can also have an impact on human health. Here, we review the current knowledge about the role of oxysterols and phytosterols on human health and focus on the impact of their pathways on diseases of the central nervous system (CNS), autoimmune diseases, including inflammatory bowel diseases (IBD), vascular diseases, and cancer in both experimental models and human studies. We will first discuss the implications of oxysterols and then of phytosterols in different human diseases.

Adverse effect of oxidized cholesterol exposure on colitis is mediated by modulation of gut microbiota

Both cholesterol and oxidized cholesterol (OXC) are present in human diets. The incidence of inflammatory bowel diseases (IBDs) is increasing in the world. The present study was to investigate the mechanism by which OXC promotes colitis using C57BL/6 mice as a model. Results shown that more severe colitis was developed in OXC-treated mice with the administration of dextran sulfate sodium (DSS) in water. Direct effects of short-term OXC exposure on gut barrier or inflammation were not observed in healthy mice. However, OXC exposure could cause gut microbiota dysbiosis with a decrease in the relative abundance of short-train fatty acids (SCFAs)-producing bacteria (Lachnospiraceae_NK4A136_group and Blautia) and an increase in the abundance of some potential harmful bacteria (Bacteroides). OXC-induced symptoms of colitis were eliminated when mice were administered with antibiotic cocktails, indicating the promoting effect of OXC on DSS-induced colitis was mediated by its effect on gut microbiota. Moreover, bacteria-depleted mice colonized with gut microbiome from OXC-DSS-exposed mice exhibited a severe colitis, further proving the gut dysbiosis caused by OXC exposure was the culprit in exacerbating the colitis. It was concluded that dietary OXC exposure increased the susceptibility of colitis in mice by causing gut microbiota dysbiosis.

In situ measurement of viscoelastic properties of cellular monolayers via graphene strain sensing of elastohydrodynamic phenomena

Recent advances recognize that the viscoelastic properties of epithelial structures play important roles in biology and disease modeling. However, accessing the viscoelastic properties of multicellular structures in mechanistic or drug-screening applications has challenges in repeatability, accuracy, and practical implementation. Here, we present a microfluidic platform that leverages elastohydrodynamic phenomena, sensed by strain sensors made from graphene decorated with palladium nanoislands, to measure the viscoelasticity of cellular monolayers in situ, without using chemical labels or specialized equipment. We demonstrate platform utility with two systems: cell dissociation following trypsinization, where viscoelastic properties change over minutes, and epithelial-to-mesenchymal transition, where changes occur over days. These cellular events could only be resolved with our platform's higher resolution: viscoelastic relaxation time constants of λ = 14.5 ± 0.4 s-1 for intact epithelial monolayers, compared to λ = 13.4 ± 15.0 s-1 in other platforms, which represents a 30-fold improvement. By rapidly assessing combined contributions from cell stiffness and intercellular interactions, we anticipate that the platform will hasten the translation of new mechanical biomarkers.

Probiotic lactobacilli attenuate oxysterols-induced alteration of intestinal epithelial cell monolayer permeability: Focus on tight junction modulation

Oxidative stress and inflammation lead by dietary oxidised lipids, as oxysterols, have been linked to the loss of intestinal barrier integrity, a crucial event in the initiation and progression of intestinal disorders. In the last decade, probiotic lactobacilli have emerged as an interesting tool to improve intestinal health, thanks to their antioxidant and anti-inflammatory properties. The aim of the present study was to evaluate the ability of two commercial probiotic strains of lactobacilli (Lactiplantibacillus plantarum 299v® (DMS 9843) and Lacticaseibacillus casei DG® (CNCMI-1572)), both as live bacteria and intracellular content, to attenuate the oxysterols-induced alteration of intestinal epithelial Caco-2 cell monolayer permeability. Our investigation was focused on the modulation of tight junctions (TJs) proteins, occludin, ZO-1 and JAM-A, in relation to redox-sensitive MAPK p38 activation. Obtained results provided evidence on the ability of the two probiotics to counteract the alteration of monolayer permeability and loss of TJs proteins, at least in part, through the modulation of p38 pathway. The protective action was exerted by live bacteria, whose adhesion to Caco-2 cells was not altered by oxysterols, and bacterial intracellular components equally able to interact with the signaling pathway.

Modulation of gut microbiota and lipid metabolism in rats fed high-fat diets by Ganoderma lucidum triterpenoids

Ganoderma lucidum triterpenoids (GP) have been reported to help prevent and improve hyperlipidemia. Modulation of the gut microbiota was proposed as underlying factor as well as a novel measure to prevent and treat hyperlipidemia. The effects of GP on high-fat diet (HFD)-induced hyperlipidemia and gut microbiota modulation were determined in rats. Ultra-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-QTOF MS-MS) indicated that GP were enriched with ganoderic acids G, B, H, A, and F. After feeding with GP supplementation, serum lipid levels including total triglyceride, total cholesterol, and low-density-lipoprotein cholesterol were significantly decreased in hyperlipidemic rats. Furthermore, administration of GP also has reversed the HFD-induced gut microbiota dysbiosis, including a significant increase in Alloprevotella and reduced proportion of Blautia. The result above suggests that GP would be developed as a functional food to ameliorate lipid metabolic disorders and hyperlipidemia.

Oxysterols as Reliable Markers of Quality and Safety in Cholesterol Containing Food Ingredients and Products

Cholesterol is a lipid of high nutritional value that easily undergoes oxidation through enzymatic and non-enzymatic pathways, leading to a wide variety of cholesterol oxidation products (COPs), more commonly named oxysterols. The major oxysterols found in animal products are 7α-hydroxycholesterol, 7β-hydroxycholesterol, 7-ketocholesterol, 5α,6α-epoxycholesterol, 5β,6β-epoxycholesterol, cholestan-3β,5α,6β-triol, and 25-hydroxycholesterol. They are all produced by cholesterol autoxidation, thus belonging to the non-enzymatic oxysterol subfamily, even if 7α-hydroxycholesterol and 25-hydroxycholesterol are, in part, generated enzymatically as well. A further oxysterol of the full enzymatic origin has recently been detected for the first time in milk of both human and bovine origin, namely 27-hydroxycholesterol. Nowadays, gas or liquid chromatography combined to mass spectrometry allows to measure all these oxysterols accurately in raw and in industrially processed food. While non-enzymatic oxysterols often exhibited in vitro relevant cytotoxicity, above all 7β-hydroxycholesterol and 7-ketocholesterol, 27-hydroxycholesterol, as well as 25-hydroxycholesterol, shows a broad spectrum in vitro antiviral activity, inhibition of SARS-CoV-2 included, and might contribute to innate immunity. Quantification of oxysterols was afforded over the years, almost always focused on a few family's compounds. More comprehensive COPs measurements, also including oxysterols of enzymatic origin, are, nowadays, available, which better display the many advantages of systematically adopting this family of compounds as markers of quality, safety, and nutritional value in the selection of ingredients in processing and storage. Regarding foodstuff shelf life, COPs monitoring already provided useful hints for more suitable packaging. The identification of a subset of non-enzymatic and enzymatic oxysterols to be routinely assessed in food production and storage is proposed.

Dietary cholesterol oxidation products: Perspectives linking food processing and storage with health implications

Dietary cholesterol oxidation products (COPs) are heterogeneous compounds formed during the processing and storage of cholesterol-rich foods, such as seafood, meat, eggs, and dairy products. With the increased intake of COPs-rich foods, the concern about health implications of dietary COPs is rising. Dietary COPs may exert deleterious effects on human health to induce several inflammatory diseases including atherosclerosis, neurodegenerative diseases, and inflammatory bowel diseases. Thus, knowledge regarding the effects of processing and storage conditions leading to formation of COPs is needed to reduce the levels of COPs in foods. Efficient methodologies to determine COPs in foods are also essential. More importantly, the biological roles of dietary COPs in human health and effects of phytochemicals on dietary COPs-induced diseases need to be established. This review summarizes the recent information on dietary COPs including their formation in foods during their processing and storage, analytical methods of determination of COPs, metabolic fate, implications for human health, and beneficial interventions by phytochemicals. The formation of COPs is largely dependent on the heating temperature, storage time, and food matrices. Alteration of food processing and storage conditions is one of the potent strategies to restrict hazardous dietary COPs from forming, including maintaining relatively low temperatures, shorter processing or storage time, and the appropriate addition of antioxidants. Once absorbed into the circulation, dietary COPs can contribute to the progression of several inflammatory diseases, where the absorbed dietary COPs may induce inflammation, apoptosis, and autophagy in cells in the target organs or tissues. Improved intake of phytochemicals may be an effective strategy to reduce the hazardous effects of dietary COPs.

Oxysterols in stored powders as potential health hazards

Cholesterol oxidation products (COPs) have greater biological activity than cholesterol itself. Oxysterols reduce the nutritional value of foods and exhibit a wide range of biological activity, including pro-oxidant, carcinogenic, and cytotoxic properties. The most commonly detected oxysterols in foods are 7α-HC, 7β-HC, a product of their dehydrogenation 7-KC and α-CE, β-CE. The main dietary sources of oxysterols are eggs and egg-derived products, thermally processed milk and milk-based products, fried meat. This study aimed to measure the amount of cholesterol oxidation products in milk powder, egg powder and milk-egg powder during 24 months of storage. The changes in the selected oxysterols (determined by gas chromatography) were recorded. In milk powder, after the production process, the amount of cholesterol was 0.2 g 100 g^-1 fat and in egg powder it was 3.4 g 100 g^-1. After 6 months of storage, the dominant oxysterol in milk and egg powder was 7α-HC and in milk-egg powder it was 7-KC. After the storage period, oxysterols in powdered milk reached 1.81% of total cholesterol.  The most stable cholesterol was in the milk-egg mixture and its oxidation was the slowest. This study showed the presence of COPs in milk powder, egg powder and milk-egg powder and the effect of storage on cholesterol oxidation.

Helianthus Annuus L. Alleviates High-Fat Diet Induced Atherosclerosis by Regulating Intestinal Microbiota, Inhibiting Inflammation and Restraining Oxidative Stress

Helianthus Annuus L. (HAL) is composed of flavonoids and polysaccharides. Flavonoids have demonstrated beneficial effects on atherosclerosis (AS). The objective of this study was to investigate the anti-atherosclerosis effect and the related mechanism of HAL. In this study, the AS model induced by high-fat diet (HFD) mice that lacked apolipoprotein E (Apoe[Formula: see text] received feed containing 5% HAL for 24 weeks. After administration, the analysis of plaque on aorta was conducted, and the possible mechanisms were further explored. With HAL treatment, the size of atherosclerotic lesions in HFD-induced AS model mice was reduced. HAL ameliorated dyslipidemia and decreased the combined ratio. HAL up-regulated concentrations of superoxide dismutase (SOD), nitric oxide (NO) and glutathione peroxidase (GSH-Px) and down-regulated concentrations of malondialdehyde (MDA) in the aorta. In addition, 16S rRNA analysis showed that HAL also reduced diversity of the intestinal microbiota, decreased the Firmicutes-to-Bacteroidetes ratio, and increased the relative abundance of probiotics such as Akkermansia muciniphila and Lactobacillus. In the end, HAL decreased the permeability of intestine by increasing the levels of occludin and tight junction protein 1 (ZO-1) in the colon, consequently decreasing concentration of interleukin (IL)-6, IL-1[Formula: see text] and tumor necrosis factor-alpha (TNF-[Formula: see text] in serum and mRNA expressions in the aorta. Data showed that HAL alleviates AS by restraining oxidative stress, regulating intestinal microbiota, decreasing intestinal permeability and inhibiting inflammation. Our findings provided novel insights into the role and mechanism of anti-atherogenic potential of HAL.

Protective Effect of Cocoa Bean Shell against Intestinal Damage: An Example of Byproduct Valorization

BACKGROUND

Cocoa bean shell (CBS), a main byproduct of cocoa processing, represents a source of components such as polyphenols and methylxanthines, which have been associated with a reduced risk of several diseases. Therefore, CBS has potential application as a food ingredient. Intestinal mucosa is exposed to immune and inflammatory responses triggered by dietary agents, such as oxysterols, which derive from cholesterol oxidation and are pro-oxidant compounds able to affect intestinal function. We aimed at investigating the capability of the Forastero cultivar CBS, added or not added to ice cream, to protect against the intestinal barrier damage induced by a dietary oxysterol mixture.

METHODS

Composition and antioxidant capacity of in vitro digested CBS and CBS-enriched ice cream were analyzed by high-performance liquid chromatography and 1,1-diphenyl-2-picryl-hydrazyl radical-scavenging assay, respectively. CaCo-2 cells differentiated into enterocyte-like monolayer were incubated with 60 µM oxysterol mixture in the presence of CBS formulations.

RESULTS

The oxysterol mixture induced tight junction impairment, interleukin-8 and monocyte chemoattractant protein-1 cell release, and oxidative stress-related nuclear factor erythroid 2 p45-related factor 2 response Nrf2. Both CBSs protected cells from these adverse effects, probably thanks to their high phenolic content. CBS-enriched ice cream showed the highest antioxidant capacity. Theobromine, which is in high concentrations of CBS, was also tested. Although theobromine exerted no effect on Nrf2 expression, its anti-inflammatory cooperating activity in CBS effect cannot be excluded.

CONCLUSIONS

Our findings suggest that CBS-enriched ice cream may be effective in the prevention of gut integrity damage associated with oxidative/inflammatory reactions.

Effect of Ergothioneine on 7-Ketocholesterol-Induced Endothelial Injury

Ergothioneine (ET) is a naturally occurring antioxidant that is synthesized by non-yeast fungi and certain bacteria. ET is not synthesized by animals, including humans, but is avidly taken up from the diet, especially from mushrooms. In the current study, we elucidated the effect of ET on the hCMEC/D3 human brain endothelial cell line. Endothelial cells are exposed to high levels of the cholesterol oxidation product, 7-ketocholesterol (7KC), in patients with cardiovascular disease and diabetes, and this process is thought to mediate pathological inflammation. 7KC induces a dose-dependent loss of cell viability and an increase in apoptosis and necrosis in the endothelial cells. A relocalization of the tight junction proteins, zonula occludens-1 (ZO-1) and claudin-5, towards the nucleus of the cells was also observed. These effects were significantly attenuated by ET. In addition, 7KC induces marked increases in the mRNA expression of pro-inflammatory cytokines, IL-1β IL-6, IL-8, TNF-α and cyclooxygenase-2 (COX2), as well as COX2 enzymatic activity, and these were significantly reduced by ET. Moreover, the cytoprotective and anti-inflammatory effects of ET were significantly reduced by co-incubation with an inhibitor of the ET transporter, OCTN1 (VHCL). This shows that ET needs to enter the endothelial cells to have a protective effect and is unlikely to act via extracellular neutralizing of 7KC. The protective effect on inflammation in brain endothelial cells suggests that ET might be useful as a nutraceutical for the prevention or management of neurovascular diseases, such as stroke and vascular dementia. Moreover, the ability of ET to cross the blood-brain barrier could point to its usefulness in combatting 7KC that is produced in the CNS during neuroinflammation, e.g. after excitotoxicity, in chronic neurodegenerative diseases, and possibly COVID-19-related neurologic complications.

27-Hydroxycholesterol contributes to cognitive deficits in APP/PS1 transgenic mice through microbiota dysbiosis and intestinal barrier dysfunction

Background

Research on the brain-gut-microbiota axis has led to accumulating interest in gut microbiota dysbiosis and intestinal barrier dysfunction in Alzheimer’s disease (AD). Our previous studies have demonstrated neurotoxic effects of 27-hydroxycholesterol (27-OHC) in in vitro and in vivo models. Here, alterations in the gut microbiota and intestinal barrier functions were investigated as the possible causes of cognitive deficits induced by 27-OHC treatment.

Methods

Male APP/PS1 transgenic and C57BL/6J mice were treated for 3 weeks with 27-OHC (5.5 mg/kg/day, subcutaneous injection) and either a 27-OHC synthetase inhibitor (anastrozole, ANS) or saline. The Morris water maze and passive avoidance test were used to assess cognitive impairment. Injuries of the intestine were evaluated by histopathological examination. Intestinal barrier function was assessed by plasma diamine oxidase (DAO) activity and d-lactate. Systemic and intestinal inflammation were evaluated by IL-1β, TNF-α, IL-10, and IL-17 concentrations as determined by ELISA. The fecal microbiome and short-chain fatty acids (SCFAs) were analyzed using 16S rDNA sequencing and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Tight junction proteins were evaluated in the ileum and colon by qRT-PCR and Western blots. Tight junction ultrastructure was examined by transmission electron microscopy.

Results

Treatment with 27-OHC resulted in severe pathologies in the ileum and colon. There was impaired intestinal barrier integrity as indicated by dilated tight junctions and downregulation of tight junction proteins, including occludin, claudin 1, claudin 5, and ZO-1, and signs of inflammation (increased IL-1β, TNF-α, and IL-17). Fecal 16S rDNA sequencing and taxonomic analysis further revealed a decreased abundance of Roseburia and reduced fecal levels of several SCFAs in 27-OHC-treated mice. Meanwhile, co-treatment with ANS reduced intestinal inflammation and partially preserved intestinal barrier integrity in the presence of 27-OHC.

Conclusions

The current study demonstrates for the first time that 27-OHC treatment aggravates AD-associated pathophysiological alterations, specifically gut microbiota dysbiosis and intestinal barrier dysfunction, which suggests that the gut microbiome and intestinal barrier function warrant further investigation as potential targets to mitigate the neurotoxic impact of 27-OHC on cognitive function and the development of AD.

Anti-Inflammatory and Cytoprotective Effect of Plant Sterol and Galactooligosaccharides-Enriched Beverages in Caco-2 Cells

Plant sterol (PS) (1 g/100 mL) enriched milk-based fruit beverages with or without galactooligosaccharides (GOS) (1.8 g/100 mL) were used in differentiated Caco-2 cells. Their potential cytopreventive effect against oxidative stress induced by cholesterol oxidation products (COPs) and their anti-inflammatory properties were evaluated. Preincubation (24 h) with bioaccessible fractions from beverages without and with GOS (MfB and MfB-G) completely prevented the COPs (60 μM/4 h) induced oxidative stress independent to GOS presence with exception to calcium influx and GSH content, where a partial protective effect was observed. Besides, MfB produced a significant (p < 0.05) reduction of IL-8 (40%) and IL-6 (50%) after IL-1β-induction (1 ng/mL/24 h) through the inhibition of NF-κB p65 translocation into the nucleus (16%) compared to control cells, while GOS presence compromised their anti-inflammatory effect. Therefore, PS-enriched milk-based fruit beverage could be an interesting strategy to prevent intestinal injury produced by COPs and to attenuate the pro-inflammatory process in intestinal human diseases. GOS addition had no extra beneficial antioxidant effect and even reduced their anti-inflammatory properties.

(-)-Epicatechin and NADPH oxidase inhibitors prevent bile acid-induced Caco-2 monolayer permeabilization through ERK1/2 modulation

Secondary bile acids promote gastrointestinal (GI) tract permeabilization both in vivo and in vitro. Consumption of high fat diets increases bile acid levels in the GI tract which can contribute to intestinal permeabilization and consequent local and systemic inflammation. This work investigated the mechanisms involved in bile acid (deoxycholic acid (DCA))-induced intestinal epithelial cell monolayer permeabilization and the preventive capacity of (-)-epicatechin (EC). While EC prevented high fat diet-induced intestinal permeabilization in mice, it did not mitigate the associated increase in fecal/cecal total and individual bile acids. In vitro, using differentiated Caco-2 cells as a model of epithelial barrier, EC and other NADPH oxidase inhibitors (VAS-2870 and apocynin) mitigated DCA-induced Caco-2 monolayer permeabilization. While EC inhibited DCA-mediated increase in cell oxidants, it did not prevent DCA-induced mitochondrial oxidant production. Prevention of DCA-induced ERK1/2 activation with EC, VAS-2870, apocynin and the MEK inhibitor U0126, also prevented monolayer permeabilization, stressing the key involvement of ERK1/2 in this process and its redox regulation. Downstream, DCA promoted myosin light chain (MLC) phosphorylation which was related to MLC phosphatase (MLCP) inhibition by ERK1/2. DCA also decreased the levels of the tight junction proteins ZO-1 and occludin, which can be related to MMP-2 activation and consequent ZO-1 and occludin degradation. Both events were prevented by EC, NADPH oxidase and ERK1/2 inhibitors. Thus, DCA-induced Caco-2 monolayer permeabilization occurs mainly secondary to a redox-regulated ERK1/2 activation and downstream disruption of TJ structure and dynamic. EC's capacity to mitigate in vivo the gastrointestinal permeabilization caused by consumption of high-fat diets can be in part related to its capacity to inhibit bile-induced NADPH oxidase and ERK1/2 activation.

A Dietary Mixture of Oxysterols Induces In Vitro Intestinal Inflammation through TLR2/4 Activation: The Protective Effect of Cocoa Bean Shells

BACKGROUND

Exaggerated Toll-like receptor (TLR)-mediated immune and inflammatory responses play a role in inflammatory bowel diseases. This report deals with the ability of a mixture of oxysterols widely present in cholesterol-rich foods to induce in vitro intestinal inflammation through TLR up-regulation. The anti-inflammatory action of four cocoa bean shell (CBS) extracts with different polyphenol content, was tested.

METHODS

Differentiated intestinal CaCo-2 cells were treated with a dietary oxysterol mixture (Oxy-mix) (60 µM). The expression and activation of TLR2 and TLR4, as well as the production of their downstream signaling effectors IL-8, IFNβ and TNFα were analyzed in the presence or absence of TLR antibodies. Honduras CBS extracts were characterized for their polyphenol contents; their anti-inflammatory action was analyzed in CaCo-2 cells treated with Oxy-mix.

RESULTS

Oxysterol-dependent TLR-2 and TLR4 over-expression and activation together with cytokine induction were abolished by blocking TLRs with specific antibodies. Polyphenol-rich CBS extracts consisting of high quantities of (-)-epicatechin and tannins also prevented TLR induction.

CONCLUSIONS

TLR2 and TLR4 mainly contribute to inducing oxysterol-dependent intestinal inflammation. The fractionation method of CBS allowed the recovery of fractions rich in (-)-epicatechin and tannins able to counteract oxysterol-induced inflammation, thus highlighting the beneficial biological potential of specific CBS extracts.

Increased production of 27-hydroxycholesterol in human colorectal cancer advanced stage: Possible contribution to cancer cell survival and infiltration

So far, the investigation in cancer cell lines of the modulation of cancer growth and progression by oxysterols, in particular 27-hydroxycholesterol (27HC), has yielded controversial results. The primary aim of this study was the quantitative evaluation of possible changes in 27HC levels during the different steps of colorectal cancer (CRC) progression in humans. A consistent increase in this oxysterol in CRC mass compared to the tumor-adjacent tissue was indeed observed, but only in advanced stages of progression (TNM stage III), a phase in which cancer has spread to nearby sites. To investigate possible pro-tumor properties of 27HC, its effects were studied in vitro in differentiated CaCo-2 cells. Relatively high concentrations of this oxysterol markedly increased the release of pro-inflammatory interleukins 6 and 8, monocyte chemoattractant protein-1, vascular endothelial growth factor, as well as matrix metalloproteinases 2 and 9. The up-regulation of all these molecules, which are potentially able to favor cancer progression, appeared to be dependent upon a net stimulation of Akt signaling exerted by supra-physiological amounts of 27HC.

4-Hexylresorcinol and silk sericin increase the expression of vascular endothelial growth factor via different pathways

Angiogenesis plays an important role in active inflammation and wound healing. Our results showed that silk sericin and 4-hexylresorcinol (4HR) increased vascular endothelial growth factor (VEGF) expression in a dose-dependent manner in RAW264.7 cells. Unlike 4HR, silk sericin increased the expression of hypoxia inducible factor-1α (HIF-1α) and HIF-2α. Pretreatment with an HIF inhibitor decreased the sericin-induced increase in VEGF expression. However, the HIF inhibitor did not affect the 4HR-induced increase in VEGF expression. An inhibitor of matrix metalloproteinase (MMP) declined the 4HR-induced increase in VEGF expression. Silk sericin increased production of reactive oxygen species (ROS), whereas 4HR decreased ROS. M1 markers were increased by silk sericin treatment, and M2 markers were increased by 4HR treatment. VEGF and angiogenin expression were higher in rats treated with a 4HR-incorporated silk mat than in rats treated with a silk mat alone. In conclusion, silk sericin and 4HR increased VEGF expression in RAW264.7 cells via HIF-mediated and MMP-mediated pathways, respectively. Silk sericin exerted like pro-oxidant effects and 4HR exerted anti-oxidant effects. Rats treated with a 4HR-incorporated silk mat showed higher levels of VEGF and angiogenin than those treated with a silk mat alone.

Olive oil polyphenols reduce oxysterols -induced redox imbalance and pro-inflammatory response in intestinal cells

Dietary habits may strongly influence intestinal homeostasis. Oxysterols, the oxidized products of cholesterol present in cholesterol-containing foodstuffs, have been shown to exert pro-oxidant and pro-inflammatory effects, altering intestinal epithelial layer and thus contributing to the pathogenesis of human inflammatory bowel diseases and colon cancer. Extra virgin olive oil polyphenols possess antioxidant and anti-inflammatory properties, and concentrate in the intestinal lumen, where may help in preventing intestinal diseases. In the present study we evaluated the ability of an extra virgin olive oil phenolic extract to counteract the pro-oxidant and pro-inflammatory action of a representative mixture of dietary oxysterols in the human colon adenocarcinoma cell line (Caco-2) undergoing full differentiation into enterocyte-like cells. Oxysterols treatment significantly altered differentiated Caco-2 cells redox status, leading to oxidant species production and a decrease of GSH levels, after 1 h exposure, followed by an increase of cytokines production, IL-6 and IL-8, after 24 h. Oxysterol cell treatment also induced after 48 h an increase of NO release, due to the induction of iNOS. Pretreatment with the phenolic extract counteracted oxysterols effects, at least in part by modulating one of the main pathways activated in the cellular response to the action of oxysterols, the MAPK-NF-kB pathway. We demonstrated the ability of the phenolic extract to directly modulate p38 and JNK1/2 phosphorylation and activation of NF-kB, following its inhibitor IkB phosphorylation. The phenolic extract also inhibited iNOS induction, keeping NO concentration at the control level. Our results suggest a protective effect at intestinal level of extra virgin olive oil polyphenols, able to prevent or limit redox unbalance and the onset and progression of chronic intestinal inflammation.

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Dietary oxysterols exerted pro-oxidant and pro-inflammatory effects in differentiated Caco-2 cells.

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H₂O₂ production, GSH decrease, IL-6 and IL-8 release were detected.

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NO release due to iNOS induction was higher than controls in oxysterols treated cells.

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Olive oil phenolic extract efficiently counteracted oxysterols effects.

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Phenolic extract directly modulated p38 and JNK MAPK/NF-κB signaling axis.

The Protective Mechanism of CAY10683 on Intestinal Mucosal Barrier in Acute Liver Failure through LPS/TLR4/MyD88 Pathway

The purpose of this study was to investigate the protective mechanism of HDAC2 inhibitor CAY10683 on intestinal mucosal barrier in acute liver failure (ALF). In order to establish ALF-induced intestinal epithelial barrier disruption models, D-galactosamine/LPS and LPS were, respectively, used with rats and NCM460 cell and then administrated with CAY10683. Transepithelial electrical resistance (TEER) was measured to detect the permeability of cells. Real-time PCR and Western blotting were employed to detect the key mRNA and protein levels. The intestinal epithelial tissue pathology was detected. After interfering with CAY10683, the mRNA and protein levels of TLR4, MyD88, TRIF, and TRAF6 were decreased compared with model group (P < 0.05), whereas the levels of ZO-1 and occluding were elevated (P < 0.05). The permeability was elevated in CAY10683-interfered groups, when compared with model group (P < 0.05). And the degree of intestinal epithelial tissue pathological damage in CAY10683 group was significantly reduced. Moreover, CAY10683 significantly decreased the TLR4 staining in animal tissue. The HDAC2 inhibitor CAY10683 could promote the damage of intestinal mucosal barrier in ALF through inhibiting LPS/TLR4/MyD88 pathway.