Indirectly stimulation of DCs by Ganoderma atrum polysaccharide in intestinal-like Caco-2/DCs co-culture model based on RNA-seq

Bound polyphenols in insoluble dietary fiber of navel orange peel modulate LPS-induced intestinal-like co-culture inflammation through CSF2-mediated NF-κB/JAK-STAT pathway

Our laboratory previously extracted bound polyphenols (BPP) in insoluble dietary fiber from navel orange peel (NOP-IDF), and the aim of this study was to investigate the anti-inflammatory activity and potential molecular mechanisms of BPP by establishing an LPS-induced intestinal-like Caco-2/RAW264.7 co-culture inflammation model. The results demonstrated that BPP reduced the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), as well as the production of pro-inflammatory cytokines, nitric oxide (NO), and reactive oxidative species (ROS) during the inflammatory damage process. Furthermore, BPP alleviated the lipopolysaccharides (LPS)-induced intestinal barrier damage by attenuating the decrease in trans-epithelial electrical resistance (TEER), diamine oxidase (DAO) activity, and intestinal alkaline phosphatase (IAP) activity, as well as the downregulation of ZO-1, Occludin, and Claudin-1 protein expression levels. RNA-seq results on RAW264.7 cells in the co-culture model showed that the NF-κB and JAK-STAT pathways belonged to the most significantly affected signaling pathways in the KEGG analysis, and western blot confirmed that they are essential for the role of BPP in intestinal inflammation. Additionally, overexpression of the granulocyte-macrophage colony-stimulating factor (CSF2) gene triggered abnormal activation of the NF-κB and JAK-STAT pathways and high-level expression of inflammatory factors, while BPP effectively improved this phenomenon. The above results suggested that BPP could inhibit intestinal inflammatory injury and protect intestinal barrier integrity through CSF2-mediated NF-κB and JAK-STAT pathways.

Disruption of intestinal epithelial permeability in the Co-culture system of Caco-2/HT29-MTX cells exposed individually or simultaneously to acrylamide and ochratoxin A

Mycotoxins and thermal processing hazards are common contaminants in various foods and cause severe problems in terms of food safety and health. Combined use of acrylamide (AA) and ochratoxin A (OTA) would result in more significant intestinal toxicity than either toxin alone, but the underlying mechanisms behind this poor outcome remain unclear. Herein, we established the co-culture system of Caco-2/HT29-MTX cells for simulating a real intestinal environment that is more sensitive to AA and OTA, and showed that the combination of AA and OTA could up-regulate permeability of the intestine via increasing LY permeabilization, and decreasing TEER, then induce oxidative stress imbalance (GSH, SOD, MDA, and ROS) and inflammatory system disorder (TNF-α, IL-1β, IL-10, and IL-6), thereby leading a rapid decline in cell viability. Western blot, PAS- and AB-staining revealed that AA and OTA showed a synergistic effect on the intestine mainly through the disruption of tight junctions (TJs) and a mucus layer. Furthermore, based on correlation analysis, oxidative stress was more relevant to the mucus layer and TJs. Therefore, our findings provide a better evaluation model and a potential mechanism for further determining or preventing the combined toxicity caused by AA and OTA.

RNA-Seq analysis of long non-coding RNA in human intestinal epithelial cells infected by Shiga toxin-producing Escherichia coli

BACKGROUND

The Shiga toxin-producing Escherichia coli (STEC) infects animals and induces acute intestinal inflammation. Long non-coding RNAs (lncRNAs) are known to play crucial roles in modulating inflammation response. However, it is not clear whether lncRNAs are involved in STEC-induced inflammation.

METHODS AND RESULTS

To understand the association of lncRNAs with STEC infection, we used RNA-seq technology to analyze the profiles of lncRNAs in Mock-infected and STEC-infected human intestinal epithelial cells (HIECs). We detected a total of 702 lncRNAs differentially expressed by STEC infection. 583 differentially expressed lncRNAs acted as competitive microRNAs (miRNAs) binding elements in regulating the gene expression involved in TNF signaling pathway, IL-17 signaling pathway, PI3K-Akt signaling pathway, and apoptosis pathways. We analyzed 3 targeted genes, TRADD, TRAF1 and TGFB2, which were differentially regulated by mRNA-miRNA-lncRNA interaction network, potentially involved in the inflammatory and apoptotic response to STEC infection. Functional analysis of up/downstream genes associated with differentially expressed lncRNAs revealed their role in adheres junction and endocytosis. We also used the qRT-PCR technique to validate 8 randomly selected differentially expressed lncRNAs and mRNAs in STEC-infected HIECs.

CONCLUSION

Our results, for the first time, revealed differentially expressed lncRNAs induced by STEC infection of HIECs. The results will help investigate the molecular mechanisms for the inflammatory responses induced by STEC.

Exploitation of In Vivo-Emulated In Vitro System in Advanced Food Science

Reasonable model construction contributes to the accuracy of experimental results. Multiple in vivo models offer reliable choices for effective evaluation, whereas their applications are hampered due to adverse features including high time-consumption, high cost and ethical contradictions. In vivo-emulated in vitro systems (IVE systems) have experienced rapid development and have been brought into food science for about two decades. IVE systems' flexibly gathers the strengths of in vitro and in vivo models into one, reflecting the results in an efficient, systematic and interacted manner. In this review, we comprehensively reviewed the current research progress of IVE systems based on the literature published in the recent two decades. By categorizing the IVE systems into 2D coculture models, spheroids and organoids, their applications were systematically summarized and typically exemplified. The pros and cons of IVE systems were also thoroughly discussed, drawing attention to present challenges and inspiring potential orientation and future perspectives. The wide applicability and multiple possibilities suggest IVE systems as an effective and persuasive platform in the future of advanced food science.

BPA and its alternatives BPF and BPAF exaggerate hepatic lipid metabolism disorders in male mice fed a high fat diet

Alternatives to Bisphenol A (BPA), such as BPF and BPAF, have found increasing industrial applications. However, toxicological research on these BPA analogues remains limited. This study aimed to investigate the effects of BPA, BPF, and BPAF exposure on hepatotoxicity in mice fed with high-fat diets (HFD). Male mice were exposed to the bisphenols at a dose of 0.05 mg per kg body weight per day (mg/kg bw/day) for eight consecutive weeks, or 5 mg/kg bw/day for the first week followed by 0.05 mg/kg bw/day for seven weeks under HFD. The low dose (0.05 mg/kg bw/day) was corresponding to the tolerable daily intake (TDI) of BPA and the high dose (5 mg/kg bw/day) was corresponding to its no observed adverse effect level (NOAEL). Biochemical analysis revealed that exposure to these bisphenols resulted in liver damage. Metabolomics analysis showed disturbances of fatty acid and lipid metabolism in bisphenol-exposed mouse livers. BPF and BPAF exposure reduced lipid accumulation in HFD mouse liver by lowering glyceride and cholesterol levels. Transcriptomics analysis demonstrated that expression levels of genes related to fatty acid synthesis and metabolism were changed, which might be related to the activation of the PPAR signaling pathway. Besides, a feedback regulation mechanism might exist to maintain hepatic metabolic homeostasis. For the first time, this study demonstrated the effects of BPF and BPAF exposure in HFD-mouse liver. Considering the reality of the high prevalence of obesity nowadays and the ubiquitous environmental distribution of bisphenols, this study provides insight and highlights the adverse effects of BPA alternatives, further contributing to the consideration of the safe use of such compounds.

Molecular Mechanisms Associated with Protecting IEC-6 Cells from Acrylamide-Induced Tight Junction Damage by Ganoderma atrum Polysaccharide

SCOPE

The previous in vivo studies show Ganoderma atrum polysaccharide (PSG-F₂ ) has a protective effect against the acrylamide (AA)-induced intestinal oxidative damage in rats. Now, this study aims to explore the protective mechanism with IEC-6 cell model.

METHODS AND RESULTS

Based on RNA Sequencing (RNA-Seq), the study screens MAPK signaling pathway as one of the most crucial pathways for pretreatment with PSG-F₂   against AA-induced damage in IEC-6 cells. In total, six key MAPK signaling pathway-related proteins (p-P38/P38, p-ERK/ERK, and p-JNK/JNK), and three tight junction key proteins (Zonula Occludens protein-1, Claudin-1, and Occludin) are detected by Western blot and immunofluorescence, which verify the RNA-Seq data. Moreover, PD98059 interference inhibits critical proteins in the MAPK signaling pathway, thus uncovering the precise molecular mechanisms of MAPK/ERK signaling pathway involve in the protective effects of PSG-F₂ against AA-induced intestinal barrier damage.

CONCLUSION

These findings confirm that PSG-F₂ can be used as a daily dietary supplement to protect the intestinal cells from damage caused by thermal processing hazards AA.

Polysaccharides as antioxidants and prooxidants in managing the double-edged sword of reactive oxygen species

Polysaccharides, a class of naturally occurring carbohydrates, were widely presented in animals, plants, and microorganisms. Recently, health benefits of polysaccharides have attracted much attention due to their unique characteristics in reactive oxygen species (ROS) management. ROS, by-products of aerobic metabolism linked to food consumption, exhibited a dual role in protecting cells and fostering pathogenesis collectively termed double-edged sword. Some interesting studies reported that polysaccharides could behave as prooxidants under certain conditions, besides antioxidant capacities. Potentiation of the bright side of ROS could contribute to the host defense that was vitally important for the polysaccharides acting as biological response modifiers. Correspondingly, disease prevention of polysaccharides linked to the management of ROS production was systematically described and discussed in this review. Furthermore, major challenges and future prospects were presented, aiming to provide new insight into applying polysaccharides as functional food ingredients and medicine.

The Molecular Mechanism of Yam Polysaccharide Protected H2O2-Induced Oxidative Damage in IEC-6 Cells

Oxidative stress is involved in maintaining homeostasis of the body, and an in-depth study of its mechanism of action is beneficial for the prevention of chronic illnesses. This study aimed to investigate the protective mechanism of yam polysaccharide (CYP) against H₂O₂-induced oxidative damage by an RNA-seq technique. The expression of genes and the function of the genome in the process of oxidative damage by H₂O₂ in IEC-6 cells were explored through transcriptomic analysis. The results illustrated that H₂O₂ damaged cells by promoting cell differentiation and affecting tight junction proteins, and CYP could achieve cell protection via restraining the activation of the MAPK signaling pathway. RNA-seq analysis revealed that H₂O₂ may damage cells by promoting the IL-17 signaling pathway and the MAPK signaling pathway and so forth. The Western blot showed that the pretreatment of CYP could restrain the activation of the MAPK signaling pathway. In summary, this study demonstrates that the efficacy of CYP in modulating the MAPK signaling pathway against excessive oxidative stress, with a corresponding preventive role against injury to the intestinal barrier. It provides a new perspective for the understanding of the preventive role of CYP on intestinal damage. These findings suggest that CYP could be used as oxidation protectant and may have potential application prospects in the food and pharmaceutical industries.

Peucedanum praeruptorum Dunn polysaccharides regulate macrophage inflammatory response through TLR2/TLR4-mediated MAPK and NF-κB pathways

The present study was to investigate the molecular mechanisms underlying macrophage inflammatory response to polysaccharides from Peucedanum praeruptorum Dunn (PPDs) and elucidate the receptors and signaling pathways associated with PPDs-mediated macrophage activation. MTT and Griess method were performed to investigate the effects of PPDs on cell viability and NO production. Neutral red and FITC-dextran were used to determine the pinocytic and phagocytic activity. RT-qPCR and ELISA were employed to analyze the mRNA expression of inflammatory factors and production of cytokines and chemokines. RNA-seq and bioinformatics analysis were conducted to determine the underlying molecules, regulators and pathways, which were further validated by pathway inhibition and neutralization assays. The results indicated that PPDs significantly enhanced pinocytic and phagocytic activity, promoted the expression and secretion of inflammatory factors and chemokines, and boosted the expression of accessory and costimulatory molecules. RNA-Seq analysis identified 1343 DEGs, 405 GO terms and 91 KEGG pathways. IL6 and TNF were identified as hubs of connectivity in PPDs-mediated macrophage activation. "Cytokine-cytokine receptor interaction", "TNF signaling pathway", "NF-kappa B signaling pathway", "JAK-STAT signaling pathway" and "MAPK signaling pathway" were the most significant pathways. The pathway inhibition assay revealed that MAPK and NF-κB pathways were essential to macrophage activation by PPDs. TLR2 and TLR4 were uncovered to be the functional receptors and involved in recognition of PPDs. These results indicated that PPDs modulated macrophage inflammatory response mainly through TLR2/TLR4-dependent MAPK and NF-κB pathways.

Protective Effect of Ganoderma atrum Polysaccharide on Acrolein-Induced Apoptosis and Autophagic Flux in IEC-6 Cells

This study was designed to explore the beneficial effect and mechanism of Ganoderma atrum (G. atrum) polysaccharide (PSG-1) on acrolein-induced IEC-6 cells. Our results indicated that PSG-1 significantly reduced the impairment of acrolein on cell viability, decreased oxidative stress, and enabled normal expression of tight junction (TJ) proteins that were inhibited by acrolein in IEC-6 cells. Furthermore, PSG-1 attenuated the elevation of microtubule-associated proteins light chain 3 (LC3) and Beclin 1-like protein 1 (Beclin 1) and increased the protein levels of phospho-mTOR (p-mTOR) and phospho-akt (p-akt), indicating that PSG-1 activated the mammalian target of rapamycin (mTOR) signaling pathway and alleviated acrolein-induced autophagy in IEC-6 cells. Moreover, PSG-1 markedly attenuated the acrolein-induced apoptosis, as evidenced by the increase in mitochondrial membrane potential (MMP) and B-cell lymphoma 2 (Bcl-2) expression, and the decrease in cysteine aspartate lyase (caspase)-3 and caspase-9. In addition, autophagy the inhibitor inhibited acrolein-induced TJ and apoptosis of IEC-6 cells, while the apoptosis inhibitor also inhibited acrolein-induced TJ and autophagy, suggesting that autophagy and apoptosis were mutually regulated. Taken together, the present study proved that PSG-1 could protect IEC-6 cells from acrolein-induced oxidative stress and could repair TJ by inhibiting apoptosis and autophagic flux, where autophagy and apoptosis were mutually regulated.

Transcriptome Analysis Reveals the Anti-cancerous Mechanism of Licochalcone A on Human Hepatoma Cell HepG2

Hepatocellular carcinoma is a malignancy with a low survival rate globally, and there is imperative to unearth novel natural phytochemicals as effective therapeutic strategies. Licochalcone A is a chalcone from Glycyrrhiza that displayed various pharmacological efficacy. A globally transcriptome analysis was carried out to reveal the gene expression profiling to explore Licochalcone A's function as an anti-cancer phytochemical on HepG2 cells and investigate its potential mechanisms. Altogether, 6,061 dysregulated genes were detected (3,414 up-regulated and 2,647 down-regulated). SP1 was expected as the transcription factor that regulates the functions of most screened genes. GO and KEGG analysis was conducted, and the MAPK signaling pathway and the FoxO signaling pathway were two critical signal pathways. Protein-protein interaction (PPI) network analysis based on STRING platform to discover the hub genes (MAPK1, ATF4, BDNF, CASP3, etc.) in the MAPK signaling pathway and (AKT3, GADD45A, IL6, CDK2, CDKN1A, etc.) the FoxO signaling pathway. The protein level of essential genes that participated in significant pathways was consistent with the transcriptome data. This study will provide an inclusive understanding of the potential anti-cancer mechanism of Licochalcone A on hepatocellular, signifying Licochalcone A as a promising candidate for cancer therapy.

Effects of Two Polysaccharides from Lepidium meyenii (Maca) on Intestinal Immunity and Inflammation in vitro

In our previous studies, two polysaccharides (MC-1 and MC-2) were identified in the roots of maca (Lepidium meyenii). In this study, the effects of these two polysaccharides on intestinal immunity...

Revealing the Specific Regulations of Brassinolide on Tomato Fruit Chilling Injury by Integrated Multi-Omics

Tomato fruit is susceptible to chilling injury (CI) when stored at low temperatures, limiting its storage potential, and resulting in economic loss if inappropriate temperatures are used. Brassinolide (BR) is a plant growth regulator that is known to decrease the susceptibility of fruit to CI. In this study, transcriptome, metabolome, and proteome analysis revealed the regulation mechanism of BR treatment in alleviating tomato fruit CI. The results showed that the differentially expressed metabolites mainly included amino acids, organic acids, carbohydrates, and lipids. Differentially expressed genes (DEGs) were involved in plant cold stress response (HSFA3, SHSP, and TPR), fruit redox process (POD, PAL, and LOX), related to the fruit texture (CESA, β-Gal, and PAE), plant hormone signal transduction (ACS3, ARF, and ERF,), transcription factors (TCP, bHLH, GATA). Moreover, differentially expressed proteins were associated with fruit texture (CESA, PE, PL, and CHI), plant oxidation processes (LOX, GPX, CAT, and POD), plant cold stress response (HSF, HSP20, HSP70, and HSP90B), plant hormone signal transduction (BSK1 and JAR1) and transcription factors (WRKY and MYB). Our study showed that BR alleviates CI symptoms of tomato fruit by regulating LOX in the α-linolenic acid metabolism pathway, enhancing jasmonic acid-CoA (JA-CoA) synthesis, inhibiting cell wall and membrane lipid damage. The results provided a theoretical basis for further study on the CI mechanism of tomato fruit.

Immunomodulatory effects of polysaccharides enzymatic hydrolysis from Hericium erinaceus on the MODE-K/DCs co-culture model

The aim of this study was to explore the indirect immunomodulatory activities and its mechanism of enzymatic hydrolysis of Hericium erinaceus polysaccharides (EHEP) in the MODE-K/DCs co-culture model. According to the TEER value, transmission of phenol red and AKP activity of MODE-K cells, single model was established in order to evaluate the eligibility of MODE-K cells monolayer. Then the MODE-K/DCs co-culture model was set up and HEP and EHEP were added into the apical chamber, DCs were obtained for the expression of key surface markers, the ability of phagocytosis, the morphology, the secretion of cytokines and the production of target proteins. We found that after 21 d of culture, the MODE-K cells monolayer became intact and dense, which can be used for the MODE-K/DCs co-culture model. Under the treatment of HEP and EHEP, immature DCs become into mature DCs with the high expression of CD86 and MHCII, the low antigens up-taking, the typical morphology, the more content of IL-12 and TNF-α and the high level of TLR4, MyD88 and NF-κB proteins. However, compared with HEP, EHEP showed the better immunomodulatory activities. These findings indicated that EHEP could indirectly affect the immune function of DCs in the MODE-K/DCs co-culture model.

Hybridization With an Invasive Plant of Xanthium strumarium Improves the Tolerance of Its Native Congener X. sibiricum to Cadmium

Hybridization is one of the important factors influencing the adaptive evolution of invasive plants. According to previous studies, hybridization with an invasive plant reduces the adaptability of its native congener to environment. However, in this study, the hybridization with an invasive plant of Xanthium strumarium (LT) improves the tolerance and accumulation of its native congener Xanthium sibiricum (CR) to cadmium (Cd). Under Cd stress, X. sibiricum♀ × X. strumarium♂ (ZCR) showed higher biomass and Cd accumulation. Compared with CR, ZCR has longer vegetative and reproductive growth time. Moreover, ZCR adopted more reasonable biomass allocation strategy. ZCR increased the proportion of reproductive allocation and ensured its own survival with the increase of Cd stress. Furthermore, ZCR increased the translocation of Cd to aboveground parts and changed the distribution of Cd. A large amount of Cd is stored in senescent leaves and eliminated from the plant when the leaves fall off, which not only reduces the Cd content in the plant, but also reduces the toxicity of Cd in the normal leaves. Transcriptome analysis shows a total of 2055 (1060 up and 995 down) differentially expressed genes (DEGs) were detected in the leaves of Cd-stressed ZCR compared with CR, while only 792 (521 up and 271 down) were detected in X. strumarium♀ × X. sibiricum♂ (ZLT) compared with LT. A large number of DGEs in ZCR and ZLT are involved in abscisic acid (ABA) synthesis and signal transduction. The genes induced by ABA in ZCR, including CNGC5/20, CPK1/28, CML, PTI1-like tyrosine-protein kinase 3, respiratory burst oxidase homolog protein C, and WRKY transcription factor 33 were found differentially expressed compared CR. carotenoid cleavage dioxygenase 4, NCED1/2, phytoene synthase 2, and CYP707A involved in ABA synthesis and decomposition in ZLT were found differentially expressed compared LT. We speculated that ABA played an important role in Cd transportation of hybrids and Cd distribution in senescent and normal leaves. The results demonstrate that hybridization with an invasive plant improves the adaptability of the hybrid to Cd stress and may enhance the extinction risk of native congener in pollution environment.

"Dialogue" between Caco-2 and DCs regulated by Ganoderma atrum polysaccharide in intestinal-like Caco-2/DCs co-culture model

The previous research has indicated that Ganoderma atrum polysaccharide (PSG-1) indirectly affects the immune function of dendritic cells (DCs) in intestinal-like Caco-2/DCs co-culture model, in which NF-κB and MAPK pathway play an essential role. To explore the interaction of Caco-2 in the interaction between the intestinal epithelium and its internal immune cells, the intestinal-like Caco-2/DCs co-culture model was developed. All transcripts of Caco-2 treated with or without PSG-1 were globally screened by RNA-seq. The expression of 452 genes regulated by PSG-1 was statistically significant, the counts of up-regulated and down-regulated genes were 198 and 256, respectively. According to KEGG analysis, tumor necrosis factor (TNF)-α and NF-κB signaling pathways of Caco-2 were selected to elucidate the mechanism of interaction between Caco-2/DCs induced by PSG-1. After the addition of TNF-α inhibitor Apremilast and NF-κB inhibitor BAY11-70821 in Caco-2, expression of cytokines (TNF-α, IL-6, IL-1β, IL-10), chemokines (RANTES, MIP-1α, MCP-1), and the key proteins of MAPK and NF-κB pathways of DCs were all reduced. In summary, "dialogue" between Caco-2 and DCs was regulated by PSG-1 through TNF-α and NF-κB signaling pathways of Caco-2 in the model.

A Ganoderma atrum polysaccharide alleviated DSS-induced ulcerative colitis by protecting the apoptosis/autophagy-regulated physical barrier and the DC-related immune barrier

Polysaccharides are one of the main active substances in Ganoderma atrum (G. atrum). The purpose of this study was to explore the protective effect of a G. atrum polysaccharide (PSG-1) on DSS-induced colitis and the underlying mechanism. The results showed that PSG-1 could maintain the integrity of the intestinal structure by promoting the expression of goblet cells and levels of tight junction proteins in the colon of DSS-induced colitis mice. Furthermore, PSG-1 relieved the inhibition of Bcl-2 and the overexpression of caspase-3 and caspase-9 caused by DSS. Simultaneously, PSG-1 restored the expression of Atg5, Atg7 and beclin-1 and inhibited the p-akt and p-mTOR levels, suggesting that PSG-1 promoted autophagy via the Akt/mTOR pathway. Moreover, PSG-1 inhibited the content of DCs in the colon and modulated the expression of IL-10 in DCs. In conclusion, PSG-1 alleviated DSS-induced ulcerative colitis by protecting the apoptosis/autophagy-regulated physical barrier and the DC-related immune barrier.