Apple polyphenols suppress antigen presentation of ovalbumin by THP-1-derived dendritic cells

Immunomodulatory effects of trastuzumab deruxtecan through the cGAS-STING pathway in gastric cancer cells

Although the efficacy of trastuzumab deruxtecan (T-DXd) against HER2-positive gastric cancers (GCs) has driven its clinical application, the precise mechanisms governing its immunomodulatory role remain unclear. In this study, we examined the immune-related mechanisms of action of T-DXd in GC cells. T-DXd exhibited potent antitumor effects in GC cells across diverse HER2 expression levels by inducing DNA damage and apoptosis. Activation of the DNA damage response by T-DXd led to increased PD-L1 expression. RNA-Seq analysis revealed that T-DXd modulated immune-related pathways, resulting in the upregulation of genes associated with inflammation and IFN signaling. Importantly, T-DXd activated the cGAS-STING pathway, inducing an IFN-I response in HER2-positive GC cells. Furthermore, T-DXd activated dendritic cells via the cancer cell-intrinsic cGAS-STING-IFN axis and enhanced PBMC-mediated tumor cell killing by activating CD8+ T cells. These findings provide valuable insights into the role of the cytosolic DNA sensing pathway in the action of T-DXd and offer a compelling rationale for combining T-DXd with immune checkpoint blockade therapies in GC treatment.

Intestinal Epithelial Co-Culture Sensitivity to Pro-Inflammatory Stimuli and Polyphenols Is Medium-Independent

The complexification of in vitro models requires the compatibility of cells with the same medium. Since immune cells are the most sensitive to growth conditions, growing intestinal epithelial cells in their usual medium seems to be necessary. This work was aimed at comparing the sensitivity of these epithelial cells to pro-inflammatory stimuli but also to dietary polyphenols in both DMEM and RPMI-1640 media. Co-cultures of Caco-2 and HT29-MTX cells were grown for 21 days in the two media before their stimulation with a cocktail of TNF-α (20 ng/mL), IL-1β (1 ng/mL), and IFN-γ (10 ng/mL) or with LPS (10 ng/mL) from E. coli (O111:B4). The role of catechins (15 µM), a dietary polyphenol, was evaluated after its incubation with the cells before their stimulation for 6 h. The RPMI-1640 medium did not alter the intensity of the inflammatory response observed with the cytokines. By contrast, LPS failed to stimulate the co-culture in inserts regardless of the medium used. Lastly, catechins were unable to prevent the pro-inflammatory response observed with the cytokines in the two media. The preservation of the response of this model of intestinal epithelium in RPMI-1640 medium is promising when considering its complexification to evaluate the complex cellular crosstalk leading to intestinal homeostasis.

Deubiquitinase OTUD6A Regulates Innate Immune Response via Targeting UBC13

OTUD6A is a deubiquitinase that plays crucial roles in various human diseases. However, the precise regulatory mechanism of OTUD6A remains unclear. In this study, we found that OTUD6A significantly inhibited the production of type I interferon. Consistently, peritoneal macrophages and bone marrow-derived macrophages from Otud6a-/- mice produced more type I interferon after virus infection compared to cells from WT mice. Otud6a-/-- mice also exhibited increased resistance to lethal HSV-1 and VSV infections, as well as LPS attacks due to decreased inflammatory responses. Mechanistically, mass spectrometry results revealed that UBC13 was an OTUD6A-interacting protein, and the interaction was significantly enhanced after HSV-1 stimulation. Taken together, our findings suggest that OTUD6A plays a crucial role in the innate immune response and may serve as a potential therapeutic target for infectious disease.

Cell-penetrating albumin enhances the sublingual delivery of antigens through macropinocytosis

Innovations in oral immunotherapy have greatly advanced the therapeutic control of allergies. However, these therapeutic effects suffer from the fact that the amount of antigen delivered to antigen-presenting cells is limited given the formulations that are currently available. We recently designed a cell-penetrating albumin and found that this modified albumin enters cells via the induction of macropinocytosis. Herein, we report on a novel system for delivering antigens based on cell-penetrating albumin-inducible macropinocytosis that allows larger amounts of antigens to be delivered to antigen-presenting cells. A treatment with cell-penetrating albumin significantly increased the permeability of ovalbumin (45 kDa) or dextran (2000 kDa) on monolayers derived from human oral squamous carcinoma cells. Flow cytometric analyses showed that the cell-penetrating albumin treatment resulted in a significant elevation in the amount of dextran that was delivered to two types of antigen-presenting cells. Finally, mice that had been sensitized by Japanese cedar pollen extract (JCPE) and cell-penetrating albumin showed a decline in the frequency of nose-rubbing against a subsequent intranasal administration of JCPE. These findings suggest that the sublingual administration of cell-penetrating albumin efficiently delivers antigens to antigen-presenting cells via the induction of macropinocytosis, resulting in an enhancement in the therapeutic effect of sublingual immunotherapy.

A review on polyphenols and their potential application to reduce food allergenicity

This review summarized recent studies about the effects of polyphenols on the allergenicity of allergenic proteins, involving epigallocatechin gallate (EGCG), caffeic acid, chlorogenic acid, proanthocyanidins, quercetin, ferulic acid and rosmarinic acid, etc. Besides, the mechanism of polyphenols for reducing allergenicity was discussed and concluded. It was found that polyphenols could noncovalently (mainly hydrophobic interactions and hydrogen bonding) and covalently (mainly alkaline, free-radical grafting, and enzymatic method) react with allergens to induce the structural changes, resulting in the masking or/and destruction of epitopes and the reduction of allergenicity. Oral administration in murine models showed that the allergic reaction might be suppressed by regulating immune cell function, changing the levels of cytokines, suppressing of MAPK, NF-κb and allergens-presentation pathway and improving intestine function, etc. The outcome of reduced allergenicity and suppressed allergic reaction was affected by many factors such as polyphenol types, polyphenol concentration, allergen types, pH, oral timing and dosage. Moreover, the physicochemical and functional properties of allergenic proteins were improved after treatment with polyphenols. Therefore, polyphenols have the potential to produce hypoallergenic food. Further studies should focus on active concentrations and bioavailability of polyphenols, confirming optimal intake and hypoallergenic of polyphenols based on clinical trials.

Deubiquitylating enzymes: potential target in autoimmune diseases

The ubiquitin-proteasome pathway is responsible for the turnover of different cellular proteins, such as transport proteins, presentation of antigens to the immune system, control of the cell cycle, and activities that promote cancer. The enzymes which remove ubiquitin, deubiquitylating enzymes (DUBs), play a critical role in central and peripheral immune tolerance to prevent the development of autoimmune diseases and thus present a potential therapeutic target for the treatment of autoimmune diseases. DUBs function by removing ubiquitin(s) from target protein and block ubiquitin chain elongation. The addition and removal of ubiquitin molecules have a significant impact on immune responses. DUBs and E3 ligases both specifically cleave target protein and modulate protein activity and expression. The balance between ubiquitylation and deubiquitylation modulates protein levels and also protein interactions. Dysregulation of the ubiquitin-proteasome pathway results in the development of various autoimmune diseases such as inflammatory bowel diseases (IBD), psoriasis, multiple sclerosis (MS), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). This review summarizes the current understanding of ubiquitination in autoimmune diseases and focuses on various DUBs responsible for the progression of autoimmune diseases.

Enhanced Inhibition of Adipogenesis by Chrysin via Modification in Redox Balance, Lipogenesis, and Transcription Factors in 3T3-L1 Adipocytes in Comparison with Hesperidin

OBJECTIVE

The present study was conducted to elucidate the in-vitro anti-oxidant and anti-adipogenic effect of the flavone, chrysin in comparison with the citrus bioflavonoid, hesperidin during adipogenic differentiation in 3T3-L1 mouse preadipocytes.

METHODS

The effect of chrysin and hesperidin on adipogenic differentiation was evaluated using Oil red-O staining, triglyceride estimation, free glycerol release, and ROS accumulation. The expression of adipogenesis-related genes was evaluated in real time-polymerase chain reaction.

RESULTS

50 µmol chrysin or hesperidin did not affect the cell viability of 3T3-L1 preadipocytes and adipocytes, but significantly reduced preadipocyte clonal population, accumulation of intracellular lipid and ROS and consequently increased lipolysis and antioxidant enzyme defence. It also decreased the expression of major adipogenic transcription factors, CCAAT/enhancer-binding protein-β, peroxisome proliferator activated receptor-γ, sterol regulatory element binding protein 1c, fatty acid synthase and hormone sensitive lipase.

CONCLUSION(S)

Herein we have indicated, for the first time, the effective anti-adipogenic mechanism of chrysin by down-regulating adipogenesis, lipogenesis and ROS and up-regulating lipolysis and antioxidant enzyme in differentiated 3T3-L1 adipocytes. As a nutritional bioflavonoid, chrysin with its more effective inhibition on adipogenesis than hesperidin has the potential to be developed as an anti-adipogenic nutraceutical agent.

A Futile Metabolic Cycle of Fatty Acyl-CoA Hydrolysis and Resynthesis in Corynebacterium glutamicum and Its Disruption Leading to Fatty Acid Production

Fatty acyl-CoA thioesterase (Tes) and acyl-CoA synthetase (FadD) catalyze opposing reactions between acyl-CoAs and free fatty acids. Within the genome of Corynebacterium glutamicum, several candidate genes for each enzyme are present, although their functions remain unknown. Modified expressions of the candidate genes in the fatty acid producer WTΔfasR led to identification of one tes gene (tesA) and two fadD genes (fadD5 and fadD15), which functioned positively and negatively in fatty acid production, respectively. Genetic analysis showed that fadD5 and fadD15 are responsible for utilization of exogenous fatty acids and that tesA plays a role in supplying fatty acids for synthesis of the outer layer components mycolic acids. Enzyme assays and expression analysis revealed that tesA, fadD5, and fadD15 were co-expressed to create a cyclic route between acyl-CoAs and fatty acids. When fadD5 or fadD15 was disrupted in wild-type C. glutamicum, both disruptants excreted fatty acids during growth. Double disruptions of them resulted in a synergistic increase in production. Additional disruption of tesA revealed a canceling effect on production. These results indicate that the FadDs normally shunt the surplus of TesA-generated fatty acids back to acyl-CoAs for lipid biosynthesis and that interception of this shunt provokes cells to overproduce fatty acids. When this strategy was applied to a fatty acid high-producer, the resulting fadDs-disrupted and tesA-amplified strain exhibited a 72% yield increase relative to its parent and produced fatty acids, which consisted mainly of oleic acid, palmitic acid, and stearic acid, on the gram scale per liter from 1% glucose.IMPORTANCE The industrial amino acid producer Corynebacterium glutamicum has currently evolved into a potential workhorse for fatty acid production. In this organism, we obtained evidence showing the presence of a unique mechanism of lipid homeostasis, namely, a formation of a futile cycle of acyl-CoA hydrolysis and resynthesis mediated by acyl-CoA thioesterase (Tes) and acyl-CoA synthetase (FadD), respectively. The biological role of the coupling of Tes and FadD would be to supply free fatty acids for synthesis of the outer layer components mycolic acids and to recycle their surplusage to acyl-CoAs for membrane lipid synthesis. We further demonstrated that engineering of the cycle in a fatty acid high-producer led to dramatically improved production, which provides a useful engineering strategy for fatty acid production in this industrially important microorganism.

Targeting the ubiquitination/deubiquitination process to regulate immune checkpoint pathways

The immune system initiates robust immune responses to defend against invading pathogens or tumor cells and protect the body from damage, thus acting as a fortress of the body. However, excessive responses cause detrimental effects, such as inflammation and autoimmune diseases. To balance the immune responses and maintain immune homeostasis, there are immune checkpoints to terminate overwhelmed immune responses. Pathogens and tumor cells can also exploit immune checkpoint pathways to suppress immune responses, thus escaping immune surveillance. As a consequence, therapeutic antibodies that target immune checkpoints have made great breakthroughs, in particular for cancer treatment. While the overall efficacy of immune checkpoint blockade (ICB) is unsatisfactory since only a small group of patients benefited from ICB treatment. Hence, there is a strong need to search for other targets that improve the efficacy of ICB. Ubiquitination is a highly conserved process which participates in numerous biological activities, including innate and adaptive immunity. A growing body of evidence emphasizes the importance of ubiquitination and its reverse process, deubiquitination, on the regulation of immune responses, providing the rational of simultaneous targeting of immune checkpoints and ubiquitination/deubiquitination pathways to enhance the therapeutic efficacy. Our review will summarize the latest findings of ubiquitination/deubiquitination pathways for anti-tumor immunity, and discuss therapeutic significance of targeting ubiquitination/deubiquitination pathways in the future of immunotherapy.

A THP-1 Cell Line-Based Exploration of Immune Responses Toward Heat-Treated BLG

Allergen recognition and processing by antigen presenting cells is essential for the sensitization step of food allergy. Macrophages and dendritic cells are both phagocytic antigen presenting cells and play important roles in innate immune responses and signaling between the innate and adaptive immune system. To obtain a model system with a homogeneous genetic background, we derived macrophages and dendritic cells from THP-1 monocytes. The difference between macrophages and dendritic cells was clearly shown by differences in their transcription response (microarray) and protein expression levels. Their resemblance to primary cells was analyzed by comparison to properties as described in literature. The uptake of β-lactoglobulin after wet-heating (60°C in solution) by THP-1 derived macrophages was earlier reported to be significantly increased. To analyse the subsequent immune response, we incubated THP-1 derived macrophages and dendritic cells with native and differently processed β-lactoglobulin and determined the transcription and cytokine expression levels of the cells. A stronger transcriptional response was found in macrophages than in dendritic cells, while severely structurally modified β-lactoglobulin induced a more limited transcriptional response, especially when compared to native and limitedly modified β-lactoglobulin. These results show that processing is relevant for the transcriptional response toward β-lactoglobulin of innate immune cells.

Gliadin Sequestration as a Novel Therapy for Celiac Disease: A Prospective Application for Polyphenols

Celiac disease is an autoimmune disorder characterized by a heightened immune response to gluten proteins in the diet, leading to gastrointestinal symptoms and mucosal damage localized to the small intestine. Despite its prevalence, the only treatment currently available for celiac disease is complete avoidance of gluten proteins in the diet. Ongoing clinical trials have focused on targeting the immune response or gluten proteins through methods such as immunosuppression, enhanced protein degradation and protein sequestration. Recent studies suggest that polyphenols may elicit protective effects within the celiac disease milieu by disrupting the enzymatic hydrolysis of gluten proteins, sequestering gluten proteins from recognition by critical receptors in pathogenesis and exerting anti-inflammatory effects on the system as a whole. This review highlights mechanisms by which polyphenols can protect against celiac disease, takes a critical look at recent works and outlines future applications for this potential treatment method.

Hydrophobicity drives receptor-mediated uptake of heat-processed proteins by THP-1 macrophages and dendritic cells, but not cytokine responses

Although an impact of processing on immunogenicity of food proteins has clearly been demonstrated, the underlying mechanisms are still unclear. We applied 3 different processing methods: wet heating (60 °C) and low- or high-temperature (50 °C or 130 °C, respectively) dry-heating in absence or presence of reducing sugars, to β-lactoglobulin (BLG), lysozyme and thyroglobulin, which represent dietary proteins with different pI or molecular weight. Uptake of the soluble fraction of the samples was tested in two types of, genetically homogeneous, antigen-presenting cells (macrophages and dendritic cells derived from THP-1 monocytes). This revealed a strong correlation between the uptake of the different protein samples by macrophages and dendritic cells, and confirmed the key role of hydrophobicity, over aggregation, in determining the uptake. Several uptake routes were shown to contribute to the uptake of BLG by macrophages. However, cytokine responses following exposure of macrophages to BLG samples were not related to the levels of uptake. Together, our results demonstrate that heat-treatment-induced increased hydrophobicity is the prime driving factor in uptake, but not in cytokine production, by THP-1 macrophages.

Extracts of Tectona grandis and Vernonia amygdalina have anti-Toxoplasma and pro-inflammatory properties in vitro

Tectona grandis (teak) and Vernonia amygdalina (bitter leaf) are plants used in traditional medicine in West Africa. In this study, we tested ethanolic and hydro-ethanolic extracts of bark and leaves of T. grandis and ethanolic extract of leaves of V. amygdalina for their inhibitory effect on Toxoplasma gondii, a protozoan parasite responsible for toxoplasmosis. Ethanolic extract of V. amygdalina leaves had proportional contents of phenols, tannins, flavonoids, and polysaccharides. This extract presented the highest efficacy against T. gondii, the lowest cytotoxicity to mammalian cells, but moderate anti-oxidant activity compared to other plant extracts. Ethanolic extract of T. grandis bark also had elevated anti-T. gondii activity, low cytotoxicity on mammalian cells, and one of the highest anti-oxidant activities. However, the phytochemical content of this extract was not very different from the hydro-ethanolic extract, which had no anti-T. gondii activity. In addition, ethanolic extract of V. amygdalina leaves, but not of T. grandis bark, significantly increased the production of TNF-α and NO by antigen-presenting cells. Both extracts had the tendency to decrease expression of major histocompatibility complex molecules at the surface of antigen-presenting cells, while they did not modulate the percentage of apoptotic cells. A study of signalling pathways would help to determine the mechanisms of action of these plant extracts.

Rutinosylated Ferulic Acid Attenuates Food Allergic Response and Colitis by Upregulating Regulatory T Cells in Mouse Models

The purpose of this study was to screen phytochemicals capable of inducing immune tolerance via enhanced transforming growth factor-β1 (TGF-β1) secretion and investigate their effects in a mouse model of food allergy and colitis. In a screening test using THP-1-derived dendritic cells, a significant increase in TGF-β1 levels was observed upon treatment with ferulic acid and its glycosides, among which ferulic acid rutinoside (FAR) induced the highest level of TGF-β1 secretion. Oral administration of FAR suppressed serum levels of immunoglobulin E and histamine in ovalbumin-sensitized mice and triggered the differentiation of regulatory T (Treg) cells. In comparison to the control, FAR treatment also induced stronger TGF-β1 secretion from splenic dendritic cells. FAR treatment attenuated dextran-sulfate-sodium-induced colitis in the model mice and induced Treg differentiation. These results suggest that FAR exerts potent immunomodulatory effects against allergic and intestinal inflammatory responses by inducing Treg differentiation.

Extractable and non-extractable polyphenols from blueberries modulate LPS-induced expression of iNOS and COX-2 in RAW264.7 macrophages via the NF-κB signalling pathway

BACKGROUND

Plant polyphenols are rich in blueberries that have a wide range of properties beneficial to human health. There are two types, according to the solubility of polyphenols, which were defined as extractable polyphenols (EPP) and non-extractable polyphenols (NEPP), respectively. At present, in most of reports, 'total polyphenol' refers only to EPP excluding NEPP. In this paper, the effects of EPP and NEPP on lipopolysaccharides (LPS) induced production of nitric oxide (NO) and gene expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in RAW264.7 cells via nuclear factor-κB (NF-κB) signalling pathway were compared.

RESULTS

The results showed that EPP and NEPP from blueberries significantly inhibited the LPS-induced production of NO and gene expression of iNOS and COX-2 in cells. The constitutive level of p65 sub-unit of NF-κB was obviously detected after the treatments with EPP or NEPP. By contrast, the level of phosphorylated p65 (P-p65) was strongly inhibited by EPP or NEPP. EPP had a stronger inhibition on the gene expression of iNOS and COX-2 than that of NEPP.

CONCLUSION

These findings of inhibition of iNOS and COX-2 mRNA expression through the suppression of NF-κB suggest that EPP and ENPP from blueberries have significant anti-inflammatory effect and may be a potential medicine. © 2015 Society of Chemical Industry.

Modulation of dendritic cell immune functions by plant components

Dendritic cells (DCs) are the key linkage between innate and adoptive immune response. DCs are classified as specialized antigen-presenting cells that initiate T-cell immune responses during infection and hypersensitivity, and maintain immune tolerance to self-antigens. Initiating T-cell immune responses may be beneficial in infectious diseases or cancer management, while, immunosuppressant or tolerogenic responses could be useful in controlling autoimmunity, allergy or inflammatory diseases. Several types of plant-derived components show promising properties in influencing DC functions. Various types of these components have been proven useful in clinical application and immune-based therapy. Therefore, focusing on the benefits of plant-based medicine regulating DC functions may be useful, low-cost, and accessible strategies for human health. This review illustrates recent studies, investigating the role of plant components in manipulating DC phenotype and function towards immunostimulating or immunosuppressing effects either in vitro or in vivo.

Increasing succinic acid production using the PTS-independent glucose transport system in a Corynebacterium glutamicum PTS-defective mutant

Succinic acid synthesized from glucose shows potential as a bio-based platform chemical. However, the need for a high glucose concentration, and the accompanying low yields, limit its industrial applications. Despite efficient glucose uptake by the phosphotransferase system (PTS), 1 mol of phosphoenolpyruvate is required for each mole of internalized glucose. Therefore, a PTS-defective Corynebacterium glutamicum mutant was constructed to increase phosphoenolpyruvate availability for succinic acid synthesis, resulting in a lower glucose utilization rate and slower growth. The transcriptional regulator iolR was also deleted to enable the PTS-defective mutant to utilize glucose via iolT-mediated glucose transport. Deletion of iolR and overexpression of iolT1 and ppgk (polyphosphate glucokinase) in the PTS-deficient C. glutamicum strain completely restored glucose utilization, increasing production by 11.6 % and yield by 32.4 % compared with the control. This study revealed for the first time that iolR represses the expression of the two glucokinase genes (glk and ppgk).

Oral administration of apple condensed tannins delays rheumatoid arthritis development in mice via downregulation of T helper 17 (Th17) cell responses

Apples are known to contain high concentrations of phenolic compounds such as condensed tannins. Consumption of condensed tannins has been reported to reduce the risk of many types of chronic diseases including allergies. However, their therapeutic effectiveness and potential in treating autoimmune disease remain controversial. Here, the effect of oral administration of apple condensed tannins (ACT) prepared from apples (Malus pumila cv. Fuji) on bovine type II collagen (CII)-induced arthritis in DBA1/J mice, a well-established murine model of human rheumatoid arthritis (RA), was evaluated. As compared to the control (without ACT administration) group, RA development was delayed and a significant reduction in the RA clinical score was observed in the ACT-administered group. Using cultured splenocytes isolated from CII-immunized mice, ACT-administration was shown to decrease the CII-induced increases in IL-17 expression and production in vitro. We propose that downregulation of T helper (Th) 17 cells is responsible for the ACT-induced RA suppression.

Microbial biotransformation of bioactive flavonoids

The bioactive flavonoids are considered as the most important phytochemicals in food, which exert a wide range of biological benefits for human being. Microbial biotransformation strategies for production of flavonoids have attracted considerable interest because they allow yielding novel flavonoids, which do not exist in nature. In this review, we summarize the existing knowledge on the production and biotransformation of flavonoids by various microbes. The main reactions during microbial biotransformation are hydroxylation, dehydroxylation, O-methylation, O-demethylation, glycosylation, deglycosylation, dehydrogenation, hydrogenation, C ring cleavage of the benzo-γ-pyrone system, cyclization, and carbonyl reduction. Cunninghamella, Penicillium, and Aspergillus strains are very popular to biotransform flavonoids and they can perform almost all the reactions with excellent yields. Aspergillus niger is one of the most applied microorganisms in the flavonoids' biotransformation; for example, A. niger can transfer flavanone to flavan-4-ol, 2'-hydroxydihydrochalcone, flavone, 3-hydroxyflavone, 6-hydroxyflavanone, and 4'-hydroxyflavanone. The hydroxylation of flavones by microbes usually happens on the ortho position of hydroxyl group on the A ring and C-4' position of the B ring and microbes commonly hydroxylate flavonols at the C-8 position. The microorganisms tend to hydroxylate flavanones at the C-5, 6, and 4' positions; however, for prenylated flavanones, dihydroxylation often takes place on the C4α=C5α double bond on the prenyl group (the side chain of A ring). Isoflavones are usually hydroxylated at the C-3' position of the B ring by microorganisms. The microbes convert flavonoids to their 7-O-glycosides and 3-O-glycosides (when flavonoids have a hydroxyl moiety at the C-3 position). The demethylation of multimethoxyl flavonoids by microbes tends to happen at the C-3' and C-4' positions of the B ring. Multimethoxyl flavanones and isoflavone are demethylated at the C-7 and C-4' positions. The O-methylation of flavonols happens at the C-3' and C-4' and microorganisms O-methylate flavones at the C-6 position and the O-methylation of flavanones, usually took place on the hydroxyl groups of the A ring. The prenyl flavanones were cyclized at the prenyl side chain to form a new five-member ring attached to the A ring. Chalcones were regioselectively cyclized to flavanones. Hydrogenation of flavonoids was only reported on transformation of chalcones to dihydrochalcones. The dehydrogenation of flavanoids to flavonoids was not comprehensively studied.

A third glucose uptake bypass in Corynebacterium glutamicum ATCC 31833

In Corynebacterium glutamicum, the phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) has long been the only known glucose uptake system, but we recently found suppressor mutants emerging from a PTS-negative strain of C. glutamicum ATCC 31833 on glucose agar plates, and identified two alternative potential glucose uptake systems, the myo-inositol transporters encoded by iolT1 and iolT2. The expression of either gene renders the PTS-negative strain WTΔptsH capable of growing on glucose. In the present study, we found a suppressor strain that still grew on glucose even after the iolT1 and iolT2 genes were both disrupted under the PTS-negative background. Whole-genome sequencing of the suppressor strain SPH1 identified a G-to-T exchange at 134 bp upstream of the bglF gene encoding an EII component of the β-glucoside-PTS, which is found in limited wild-type strains of C. glutamicum. Introduction of the mutation into strain WTΔptsH allowed the PTS-negative strain to grow on glucose. Reverse transcription-quantitative PCR analysis revealed that the mutation upregulates the bglF gene by approximately 11-fold. Overexpression of bglF under the gapA promoter in strain WTΔptsH rendered the strain capable of growing on glucose, and deletion of bglF in strain SPH1 abolished the growth again, proving that bglF is responsible for glucose uptake in the suppressor strain. Simultaneous disruption of three glucokinase genes, glk (Cgl2185, NCgl2105), ppgK (Cgl1910, NCgl1835), and Cgl2647 (NCgl2558), in strain SPH1 resulted in no growth on glucose. Plasmid-mediated expression of any of the three genes in the triple-knockout mutant restored the growth on glucose. These results indicate that C. glutamicum ATCC 31833 has an additional non-PTS glucose uptake route consisting of the bglF-specified EII permease and native glucokinases.

Polyphenols from blueberries modulate inflammation cytokines in LPS-induced RAW264.7 macrophages

Polyphenols including 3-glucoside/arabinoside/galactoside-based polymers of delphinidins, petunidins, peonidins, malvidins and cyanidins are one type of biological macromolecules, which are extraordinarily rich in blueberries. Anti-inflammatory activity of blueberry polyphenols (BPPs) was investigated by using lipopolysaccharide (LPS) induced RAW264.7 macrophages. The results showed that BPPs suppressed the gene expression of IL-1β (interleukin-1β), IL-6 and IL-12p35. The inhibition effect on IL-1β and IL-6 mRNA was most obvious at the concentration of 10-200μg/mL BPPs. But the inhibition effect on IL-12p35 mRNA was increased with the increasing concentration of BPPs. When fixed at 100μg/mL BPPs, the most significant inhibition on IL-1β, IL-6 and IL-12p35 mRNA expression was detected at 12-48h. In conclusion, BPPs exhibit anti-inflammation activity by mediating and modulating the balances in pro-inflammatory cytokines of IL-1β, IL-6, and IL-12.

Development of fatty acid-producing Corynebacterium glutamicum strains

To date, no information has been made available on the genetic traits that lead to increased carbon flow into the fatty acid biosynthetic pathway of Corynebacterium glutamicum. To develop basic technologies for engineering, we employed an approach that begins by isolating a fatty acid-secreting mutant without depending on mutagenic treatment. This was followed by genome analysis to characterize its genetic background. The selection of spontaneous mutants resistant to the palmitic acid ester surfactant Tween 40 resulted in the isolation of a desired mutant that produced oleic acid, suggesting that a single mutation would cause increased carbon flow down the pathway and subsequent excretion of the oversupplied fatty acid into the medium. Two additional rounds of selection of spontaneous cerulenin-resistant mutants led to increased production of the fatty acid in a stepwise manner. Whole-genome sequencing of the resulting best strain identified three specific mutations (fasR20, fasA63(up), and fasA2623). Allele-specific PCR analysis showed that the mutations arose in that order. Reconstitution experiments with these mutations revealed that only fasR20 gave rise to oleic acid production in the wild-type strain. The other two mutations contributed to an increase in oleic acid production. Deletion of fasR from the wild-type strain led to oleic acid production as well. Reverse transcription-quantitative PCR analysis revealed that the fasR20 mutation brought about upregulation of the fasA and fasB genes encoding fatty acid synthases IA and IB, respectively, by 1.31-fold ± 0.11-fold and 1.29-fold ± 0.12-fold, respectively, and of the accD1 gene encoding the β-subunit of acetyl-CoA carboxylase by 3.56-fold ± 0.97-fold. On the other hand, the fasA63(up) mutation upregulated the fasA gene by 2.67-fold ± 0.16-fold. In flask cultivation with 1% glucose, the fasR20 fasA63(up) fasA2623 triple mutant produced approximately 280 mg of fatty acids/liter, which consisted mainly of oleic acid (208 mg/liter) and palmitic acid (47 mg/liter).