ABSTRACT
Recent evidence suggests that mulberry leaves have good antioxidant activity. However, what the antioxidant ingredient is and how the ingredient works are still not well understood. In this study, we enzymatically hydrolyze mulberry leaf proteins (MLPs) using neutral protease and find that the mulberry leaf protein hydrolysates (MLPHs) have stronger antioxidant activity compared to MLPs. We separate the core antioxidant components in MLPHs by ion-exchange columns and molecular sieves and identify 798 antioxidant peptides by LC-MS/MS. Through bioinformatics analysis and biochemical assays, we screen two previously unreported peptides, P6 and P7, with excellent antioxidant activities. P6 and P7 not only significantly reduce ROS in cells but also improve the activities of the antioxidant enzymes SOD and CAT. In addition, both peptides are found to exert protective effects against H2O2-induced chromatin damage and cell apoptosis. Collectively, these results provide support for the application of mulberry leaf peptides as antioxidants in the medical, food and livestock industries.
ABSTRACT
Mulberry is a rapidly growing plant that thrives in diverse climatic, topographical, and soil types, spanning temperature and temperate countries. Mulberry plants are valued as functional foods for their abundant chemical composition, serving as a significant reservoir of bioactive compounds like proteins, polysaccharides, phenolics, and flavonoids. Moreover, these compounds displayed potent antioxidant activity by scavenging free radicals, inhibiting reactive oxygen species generation, and restoring elevated nitric oxide production induced by LPS stimulation through the downregulation of inducible NO synthase expression. Active components like oxyresveratrol found in Morus demonstrated anti-inflammatory effects by inhibiting leukocyte migration through the MEK/ERK signaling pathway. Gallic and chlorogenic acids in mulberry leaves (ML) powder-modulated TNF, IL-6, and IRS1 proteins, improving various inflammatory conditions by immune system modulation. As we delve deeper into understanding its anti-inflammatory potential and how it works therapeutically, it is crucial to refine the extraction process to enhance the effectiveness of its bioactive elements. Recent advancements in extraction techniques, such as solid-liquid extraction, pressurized liquid extraction, superficial fluid extraction, microwave-assisted extraction, and ultrasonic-assisted extraction, are being explored. Among the extraction methods tested, including Soxhlet extraction, maceration, and ultrasound-assisted extraction (UAE), UAE demonstrated superior efficiency in extracting bioactive compounds from mulberry leaves. Overall, this comprehensive review sheds light on the potential of mulberry as a natural immunomodulatory agent and provides insights into its mechanisms of action for future research and therapeutic applications.
Subject(s)
Morus , Plant Extracts , Morus/chemistry , Plant Extracts/pharmacology , Plant Extracts/chemistry , Humans , Animals , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/chemistry , Immunomodulating Agents/pharmacology , Immunomodulating Agents/chemistry , Immunologic Factors/pharmacology , Immunologic Factors/chemistry , Plant Leaves/chemistryABSTRACT
Uracil-thymine dehydrogenase (UTDH), which catalyzes the irreversible oxidation of uracil to barbituric acid in oxidative pyrimidine metabolism, was purified from Rhodococcus erythropolis JCM 3132. The finding of unusual stabilizing conditions (pH 11, in the presence of NADP+ or NADPH) enabled the enzyme purification. The purified enzyme was a heteromer consisting of three different subunits. The enzyme catalyzed oxidation of uracil to barbituric acid with artificial electron acceptors such as methylene blue, phenazine methosulfate, benzoquinone, and α-naphthoquinone; however, NAD+, NADP+, flavin adenine dinucleotide, and flavin mononucleotide did not serve as electron acceptors. The enzyme acted not only on uracil and thymine but also on 5-halogen-substituted uracil and hydroxypyrimidine (pyrimidone), while dihydropyrimidine, which is an intermediate in reductive pyrimidine metabolism, and purine did not serve as substrates. The activity of UTDH was enhanced by cerium ions, and this activation was observed with all combinations of substrates and electron acceptors.
Subject(s)
Oxidation-Reduction , Pyrimidines , Rhodococcus , Uracil , Uracil/metabolism , Uracil/chemistry , Pyrimidines/metabolism , Rhodococcus/enzymology , NADP/metabolism , Methylene Blue/metabolism , Methylene Blue/chemistry , Barbiturates/metabolism , Barbiturates/chemistry , Benzoquinones/metabolism , Benzoquinones/chemistry , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/chemistry , Hydrogen-Ion Concentration , Thymine/metabolism , Thymine/chemistry , Substrate Specificity , Methylphenazonium Methosulfate/metabolism , Methylphenazonium Methosulfate/chemistryABSTRACT
Background: Postbiotics are an emerging research interest in recent years and are fairly advanced compared to prebiotics and probiotics. The composition and function of postbiotics are closely related to fermentation conditions. Methods: In this study, we developed a solid-state fermentation preparation method for postbiotics with antimicrobial, antioxidant, and anti-inflammatory activities. The antibacterial activity was improved 3.62 times compared to initial fermentation conditions by using optimization techniques such as single factor experiments, Plackett-Burman design (PBD), steepest ascent method (SAM), and central composite design (CCD) methods. The optimized conditions were carried out with an initial water content of 50% for 8 days at 37°C and fermentation strains of Bacillus amyloliquefaciens J and Lactiplantibacillus plantarum SN4 at a ratio of 1:1 with a total inoculum size of 8%. The optimized SSF medium content ratios of peptide powder, wheat bran, corn flour, and soybean meal were 4, 37.4, 30, and 28.6%, respectively. Results: Under these optimized conditions, postbiotics with a concentration of 25 mg/mL showed significant broad-spectrum antibacterial capabilities against Escherichia coli, Salmonella, and Staphylococcus aureus and strong antioxidant activity against ABTS, DPPH, and OH radicals. Moreover, the optimized postbiotics exhibited good anti-inflammatory ability for reducing nitric oxide (NO) secretion in RAW 264.7 macrophage cells in response to LPS-induced inflammation. Furthermore, the postbiotics significantly improved intestinal epithelial wound healing capabilities after mechanical injury, such as cell scratches in IPEC-J2 cells (p < 0.05). Conclusion: In brief, we developed postbiotics through optimized solid-state fermentation with potential benefits for gut health. Therefore, our findings suggested that the novel postbiotics could be used as potential functional food products for improving body health.
ABSTRACT
In this study, the yield of exopolysaccharide (EPS) from Lactobacillus plantarum R301 was optimized using a single-factor experiment and response surface methodology (RSM). After optimization, the EPS yield was increased with a fold-change of 0.85. The significant factors affecting EPS production, as determined through a Plackett-Burman design and Central Composite Design (CCD), were MgSO4 concentration, initial pH, and inoculation size. The maximum yield was 97.85 mg/mL under the condition of 0.01% MgSO4, an initial pH 7.4, and 6.4% of the inoculation size. In addition, the EPS exhibited strong antioxidant activity, as demonstrated by its ability to scavenge DPPH, ABTS, and hydroxyl radicals. The scavenging rate was up to 100% at concentrations of 4 mg/mL, 1 mg/mL, and 2 mg/mL, respectively. Moreover, the EPS also exhibited reducing power, which was about 30% that of ascorbic acid when both tended to be stable with the increased concentration. These results suggest that L. plantarum R301 EPS possesses different antioxidant mechanisms and warrants further investigation. In addition to its antioxidant activity, the EPS also demonstrated good anti-inflammatory activity by inhibiting the inflammation induced by lipopolysaccharide (LPS) in RAW 264.7 cells, which could decrease nitric oxide (NO) production and expression of the proinflammatory cytokine Il-6. These findings suggest that L. plantarum R301 EPS could be used as a potential multifunctional food additive in the food industry.
ABSTRACT
[Background] Bacillus LFB112 is a strain of Bacillus amyloliquefaciens screened in our laboratory. Previous studies found that it has a strong ability for fatty acid metabolism and can improve the lipid metabolism of broilers when used as feed additives. [Methods] This study aimed to confirm the fatty acid metabolism of Bacillus LFB112. Sterilized soybean oil (SSO) was added to the Beef Peptone Yeast (BPY) medium, and its effect on fatty acid content in the supernatant and bacteria, as well as expression levels of genes related to fatty acid metabolism, were studied. The control group was the original culture medium without oil. [Results] Acetic acid produced by the SSO group of Bacillus LFB112 decreased, but the content of unsaturated fatty acids increased. The 1.6% SSO group significantly increased the contents of pyruvate and acetyl-CoA in the pellets. Furthermore, the mRNA levels of enzymes involved in the type II fatty acid synthesis pathway of FabD, FabH, FabG, FabZ, FabI, and FabF were up-regulated. [Conclusions] Soybean oil increased the content of acetyl-CoA in Bacillus LFB112, activated its type II fatty acid synthesis pathway, and improved the fatty acid metabolism level of Bacillus LFB112. These intriguing results pave the way for further investigations into the intricate interplay between Bacillus LFB112 and fatty acid metabolism, with potential applications in animal nutrition and feed additive development.
ABSTRACT
BACKGROUND: Limosilactobacillusmucosae (LM) exerts anti-inflammatory and health-promoting effects. However, its role in the modulation of gut serotonin or 5-hydroxytryptamine (5-HT) metabolism and 5-HT receptors (HTRs) in inflammation requires further investigation. OBJECTIVES: We compared LM with Lactobacillus amylovorus (LA) for the regulation of 5-HT, HTRs, inflammatory mediators, and their correlations in the colon of mice with experimental colitis. METHODS: Male C57BL/6 mice were randomly assigned to 6 groups: control (Con), LM, LA, dextran sodium sulfate (DSS), and DSS with pre-administration of LM (+LM) or LA (+LA). After 7 d of DSS treatment, mice were killed to analyze the expression of inflammatory mediators, HTRs, and concentrations of 5-HT and microbial metabolites in the colon. RESULTS: LM was more effective than LA in alleviating DSS-induced colonic inflammation. Compared with mice in the DSS group, mice receiving DSS + LM or DSS + LA treatment had lower (P < 0.05) colonic mRNA expression of proinflammatory cytokines. DSS + LM treatment had lower mRNA expression of Il1b, Tnfa, and Ccl3, an abundance of p-STAT3, and greater expression of Tgfb2 and Htr4 in the colon (P < 0.05). The expression of inflammatory mediators (including Tgfb-1) was positively correlated (P < 0.05) with 5-HT and Htr2a and negatively correlated (P < 0.05) with Htr4. However, the expression of Tgfb-2 showed reversed correlations with the 5-HT and HTRs described above. Patterns for these correlations were different for LM and LA. Mice receiving the DSS + LM treatment had greater (P < 0.05) concentrations of acetate and valerate and lower (P < 0.05) concentrations of indole-3-acetic acid in the cecal and colonic contents. CONCLUSIONS: LM showed greater efficacy than LA in alleviating DSS-induced colonic inflammation. The coordinated regulation of transforming growth factor-ß subtypes and serotonin receptors in the colon may be one of the most important mechanisms underlying the probiotic effects of lactobacilli in gut inflammation.
Subject(s)
Colitis , Serotonin , Male , Animals , Mice , Serotonin/metabolism , Lactobacillus acidophilus/metabolism , Up-Regulation , Mice, Inbred C57BL , Colitis/chemically induced , Colitis/prevention & control , Colitis/metabolism , Colon/metabolism , Inflammation/metabolism , RNA, Messenger/metabolism , Transforming Growth Factors/adverse effects , Transforming Growth Factors/metabolism , Dextran Sulfate/toxicity , Disease Models, AnimalABSTRACT
Life requires ribonucleotide reduction for de novo synthesis of deoxyribonucleotides. As ribonucleotide reduction has on occasion been lost in parasites and endosymbionts, which are instead dependent on their host for deoxyribonucleotide synthesis, it should in principle be possible to knock this process out if growth media are supplemented with deoxyribonucleosides. We report the creation of a strain of Escherichia coli where all three ribonucleotide reductase operons have been deleted following introduction of a broad spectrum deoxyribonucleoside kinase from Mycoplasma mycoides. Our strain shows slowed but substantial growth in the presence of deoxyribonucleosides. Under limiting deoxyribonucleoside levels, we observe a distinctive filamentous cell morphology, where cells grow but do not appear to divide regularly. Finally, we examined whether our lines can adapt to limited supplies of deoxyribonucleosides, as might occur in the switch from de novo synthesis to dependence on host production during the evolution of parasitism or endosymbiosis. Over the course of an evolution experiment, we observe a 25-fold reduction in the minimum concentration of exogenous deoxyribonucleosides necessary for growth. Genome analysis reveals that several replicate lines carry mutations in deoB and cdd. deoB codes for phosphopentomutase, a key part of the deoxyriboaldolase pathway, which has been hypothesised as an alternative to ribonucleotide reduction for deoxyribonucleotide synthesis. Rather than complementing the loss of ribonucleotide reduction, our experiments reveal that mutations appear that reduce or eliminate the capacity for this pathway to catabolise deoxyribonucleotides, thus preventing their loss via central metabolism. Mutational inactivation of both deoB and cdd is also observed in a number of obligate intracellular bacteria that have lost ribonucleotide reduction. We conclude that our experiments recapitulate key evolutionary steps in the adaptation to life without ribonucleotide reduction.
Subject(s)
Ribonucleotide Reductases , Ribonucleotides , Ribonucleotides/metabolism , Escherichia coli/genetics , Escherichia coli/metabolism , Symbiosis , Ribonucleotide Reductases/genetics , Ribonucleotide Reductases/metabolism , Deoxyribonucleotides/metabolism , Deoxyribonucleosides/metabolismABSTRACT
The current study aimed to investigate the effects of Clostridium butyiricum on growth performance, intestinal morphology, serum biochemical response, and immunity in broiler chickens. A total of 330 commercial one-day-old, mixed-sex Ross 308 broilers were randomly divided into five treatment groups with six replicates per group. The broilers were fed the basal diet (CON), the basal diet with 150 mg/kg of aureomycin (AM), the basal diet with C. butyricum at 2 × 108 CFU/kg (CBL), the basal diet with C. butyricum at 4 × 108 CFU/kg (CBM), and the basal diet with C. butyricum at 8 × 108 CFU/kg (CBH). Results showed that the final body weight (BW) (p < 0.01; p < 0.05), ADG from day 22 to 39 (p < 0.05), and ADG from day 1 to 39 (p < 0.01; p < 0.05) were improved in a linear and quadratic response with the inclusion of C. butyricum. There were no differences in feed conversion rate (FCR) among all groups (p > 0.05). Supplementation with C. butyricum quadratically reduced the crypt depth at day 21 (p < 0.01), linearly improved the villus height in the jejunum at day 39 (p < 0.001), and linearly and quadratically increased the villus height to crypt depth (V/C) ratio in the jejunum at day 21 (p < 0.01) and day 39 (p < 0.01; p < 0.001). Dietary C. butyricum affected the thymus index at day 21 and day 39 (linear, p < 0.01), and the bursa of Fabricius index at day 39 (quadratic, p < 0.05). Compared to the AM group, the serum urea contents were decreased (p < 0.05) but the IgG contents were increased in the CBL and CBH groups at day 21 (p < 0.01); in addition, serum albumin (ALB) concentrations in all the C. butyricum-supplemented groups (p < 0.01) and IgG concentrations in the CBM group were augmented at day 39 (p < 0.05). In conclusion, dietary C. butyricum could enhance growth performance by improving jejunal morphology and stimulating immunity organ development in broilers, and could be an alternative to antibiotics in poultry feeds.
ABSTRACT
The aim of this study was to apply a strategy to express a recombinant CLP peptide and explore its application as a product derived from natural compounds. The amphiphilic CLP peptide was hybridized from three parent peptides (CM4, LL37, and TP5) and was considered to have potent endotoxin-neutralizing activity with minimal cytotoxic and hemolytic activity. To achieve high secretion expression, an expression vector of pPICZαA-HSA-CLP was constructed by the golden gate cloning strategy before being transformed into Pichia pastoris and integrated into the genome. The recombinant CLP was purified through the Ni-NTA affinity chromatography and analyzed by SDS-PAGE and mass spectrometry. The Limulus amebocyte lysate (LAL) test exhibited that the hybrid peptide CLP inhibited lipopolysaccharides (LPS) in a dose-dependent manner and was significantly (p < 0.05) more efficient compared to the parent peptides. In addition, it essentially diminished (p < 0.05) the levels of nitric oxide and pro-inflammatory cytokines (including TNF-α, IL6, and IL-1ß) in LPS-induced mouse RAW264.7 macrophages. As an attendant to the control and the parental peptide LL37, the number of LPS-induced apoptotic cells was diminished compared to the control parental peptide LL37 (p < 0.05) with the treatment of CLP. Consequently, we concluded that the hybrid peptide CLP might be used as a therapeutic agent.
Subject(s)
Incontinentia Pigmenti , Humans , Child , Incontinentia Pigmenti/diagnosis , Cytokines , Aqueous Humor , Diagnosis, DifferentialABSTRACT
Recently, the drawbacks arising from the overuse of antibiotics have drawn growing public attention. Among them, drug-resistance (DR) and even multidrug-resistance (MDR) pose significant challenges in clinical practice. As a representative of a DR or MDR pathogen, Staphylococcus aureus can cause diversity of infections related to different organs, and can survive or adapt to the diverse hostile environments by switching into other phenotypes, including biofilm and small colony variants (SCVs), with altered physiologic or metabolic characteristics. In this review, we briefly describe the development of the DR/MDR as well as the classical mechanisms (accumulation of the resistant genes). Moreover, we use multidimensional scaling analysis to evaluate the MDR relevant hotspots in the recent published reports. Furthermore, we mainly focus on the possible non-classical resistance mechanisms triggered by the two important alternative phenotypes of the S. aureus, biofilm and SCVs, which are fundamentally caused by the different global regulation of the S. aureus population, such as the main quorum-sensing (QS) and agr system and its coordinated regulated factors, such as the SarA family proteins and the alternative sigma factor σB (SigB). Both the biofilm and the SCVs are able to escape from the host immune response, and resist the therapeutic effects of antibiotics through the physical or the biological barriers, and become less sensitive to some antibiotics by the dormant state with the limited metabolisms.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/metabolism , Biofilms/growth & development , Drug Resistance, Bacterial/genetics , Staphylococcal Infections/microbiology , Staphylococcus aureus/genetics , Animals , Bacterial Proteins/genetics , Biofilms/drug effects , Gene Expression Regulation, Bacterial , Humans , Staphylococcus aureus/drug effects , Staphylococcus aureus/pathogenicityABSTRACT
CLP is a novel hybrid peptide derived from CM4, LL37 and TP5, with significantly reduced hemolytic activity and increased antibacterial activity than parental antimicrobial peptides. To avoid host toxicity and obtain high-level bio-production of CLP, we established a His-tagged SUMO fusion expression system in Escherichia coli. The fusion protein can be purified using a Nickel column, cleaved by TEV protease, and further purified in flow-through of the Nickel column. As a result, the recombinant CLP with a yield of 27.56 mg/L and a purity of 93.6% was obtained. The purified CLP exhibits potent antimicrobial activity against gram+ and gram- bacteria. Furthermore, the result of propidium iodide staining and scanning electron microscopy (SEM) showed that CLP can induce the membrane permeabilization and cell death of Enterotoxigenic Escherichia coli (ETEC) K88. The analysis of thermal stability results showed that the antibacterial activity of CLP decreases slightly below 70 °C for 30 min. However, when the temperature was above 70 °C, the antibacterial activity was significantly decreased. In addition, the antibacterial activity of CLP was stable in the pH range from 4.0 to 9.0; however, when pH was below 4.0 and over 9.0, the activity of CLP decreased significantly. In the presence of various proteases, such as pepsin, papain, trypsin and proteinase K, the antibacterial activity of CLP remained above 46.2%. In summary, this study not only provides an effective strategy for high-level production of antimicrobial peptides and evaluates the interference factors that affect the biological activity of hybrid peptide CLP, but also paves the way for further exploration of the treatment of multidrug-resistant bacterial infections.
Subject(s)
Anti-Bacterial Agents/chemistry , Antimicrobial Peptides/chemistry , Peptides/chemistry , Recombinant Fusion Proteins/genetics , Anti-Bacterial Agents/biosynthesis , Anti-Bacterial Agents/pharmacology , Antimicrobial Cationic Peptides/chemistry , Antimicrobial Cationic Peptides/genetics , Antimicrobial Peptides/biosynthesis , Antimicrobial Peptides/genetics , Antimicrobial Peptides/pharmacology , Bacteria/drug effects , Bacteria/pathogenicity , Cathelicidins/chemistry , Cathelicidins/genetics , Escherichia coli/genetics , Hemolysis/drug effects , Humans , Peptides/genetics , Peptides/pharmacology , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/pharmacologyABSTRACT
The development of a quick, single-step cloning system for generation of multiexon gene expression constructs is presented. The system allows efficient and cost-effective assembly of multiple exons of interest genes into different expression plasmids in both Escherichia coli and Pichia pastoris. The high cloning efficiency and low cost of the system make it ideal for a novel workflow for the assembly of intron-bearing genes for expression in two different expression hosts.
Subject(s)
Escherichia coli , Pichia , Transcriptome , Cloning, Molecular , DNA , Escherichia coli/genetics , Exons , Genetic Vectors , Genomics , Pichia/genetics , Plasmids/genetics , Recombinant Proteins/genetics , SaccharomycetalesABSTRACT
The innate and adaptive immune systems act in concert to protect us from infectious agents and other harmful substances. As a state of temporary or permanent immune dysfunction, immunosuppression can make an organism more susceptible to infection, organ injury, and cancer due to damage to the immune system. It takes a long time to develop new immunomodulatory agents to prevent and treat immunosuppressive diseases, with slow progress. Toll-like receptor 2 (TLR2) agonists have been reported as potential immunomodulatory candidates due to their effective activation of immune responses. It has been demonstrated that thymopentin (TP5) could modulate immunity by binding to the TLR2 receptor. However, the fairly short half-life of TP5 greatly reduces its pharmacological potential for immunosuppression therapy. Although peptide cathelicidin 2 (CATH2) has a long half-life, it shows poor immunomodulatory activity and severe cytotoxicity, which seriously hampers its clinical development. Peptide hybridization is an effective approach for the design and engineering of novel functional peptides because hybrid peptides combine the advantages and benefits of various native peptides. In this study, to overcome all these challenges faced by the parental peptides, six hybrid peptides (CaTP, CbTP, CcTP, TPCa, TPCb, and TPCc) were designed by combining the full-length TP5 with different active fragments of CATH2. CbTP, the most potent TLR2 agonist among the six hybrid peptides, was effectively screened through in silico analysis and in vitro experiments. The CbTP peptide exhibited lower cytotoxicity than either CATH2 or TP5. Furthermore, the immunomodulatory effects of CbTP were confirmed in a CTX-immunosuppressed mouse model, which showed that CbTP has increased immunopotentiating activity and physiological stability compared to the parental peptides. CbTP successfully inhibited immunosuppression and weight loss, increased immune organ indices, and improved CD4+/CD8+ T lymphocyte subsets. In addition, CbTP significantly increased the production of the cytokine TNF-α and IL-6, and the immunoglobulins IgA, IgM, and IgG. The immunoenhancing effects of CbTP were attributed to its TLR2-binding activity, promoting the formation of the TLR2 cluster, the activation of the TLR2 receptor, and thus activation of the downstream MyD88-NF-кB signaling pathway.
Subject(s)
Peptides/metabolism , T-Lymphocytes/immunology , Thymopentin/metabolism , Toll-Like Receptor 2/agonists , Animals , Cells, Cultured , Cyclophosphamide , Cytokines , Female , Humans , Immunity , Immunity, Humoral , Immunocompromised Host , Immunomodulation , Mice , Mice, Inbred BALB C , Models, Animal , Peptides/immunology , RAW 264.7 Cells , Thymopentin/immunologyABSTRACT
Immunity is a versatile defensive response that is involved in protecting against disease by identifying and destroying self and non-self harmful substances. As a state of temporary or permanent immune dysfunction, immunosuppression can make an organism more susceptible to infection, organ injury, and cancer due to damage to the immune system. It has taken a long time to develop new immunomodulatory agents to prevent and treat immunosuppressive diseases. In recent years, Toll-like receptor 2 (TLR2) agonists have been reported to have profound effects on the immune system, and they are regarded as potent immunomodulatory candidates. TP5 and LL-37, the potent immunomodulatory agents, have been reported to produce a robust innate immune response by binding to TLR2. However, their development has been weakened by several concerns, such as potential cytotoxicity, weak physiological stability and poor immunomodulatory activity. To overcome these challenges, hybridization has been proposed. Therefore, six hybrid peptides (LTPa, LTPb, LTPc, TPLa, TPLb, and TPLc) were designed by combining the full-length TP5 with a characteristic fragment of LL-37 that included LL-37 (13-36), LL-37 (17-29), and LL-37 (13-31). LTPa, the most potent TLR2 agonist, was simply and effectively screened by molecular docking and in vitro experiments. Furthermore, the immunomodulatory effects of LTPa were confirmed by a CTX-immunosuppressed murine model, which demonstrated that LTPa successfully inhibit immunosuppression, increased immune organ indices, enhanced DC maturation, regulated T lymphocyte subsets, and increased cytokine and Ig contents. Our study also revealed that the immunomodulatory effects of LTPa are associated with binding to TLR2, forming TLR2 clusters, and activating the NF-κB signaling pathway.
ABSTRACT
EF-1 is a novel peptide derived from two bacteriocins, plantaricin E and plantaricin F. It has a strong antibacterial activity against Escherichia coli and with negligible hemolytic effect on red blood cells. However, the chemical synthesis of EF-1 is limited by its high cost. In this study, we established a heterologous expression of EF-1 in Pichia pastoris. The transgenic strain successfully expressed hybrid EF-1 peptide, which had a molecular weight of ~5 kDa as expected. The recombinant EF-1 was purified by Ni2+ affinity chromatography and reversed-phase high performance liquid chromatography (RP-HPLC), which achieved a yield of 32.65 mg/L with a purity of 94.9%. The purified EF-1 exhibited strong antimicrobial and bactericidal activities against both Gram-positive and -negative bacteria. Furthermore, propidium iodide staining and scanning electron microscopy revealed that EF-1 can directly induce cell membrane permeabilization of E. coli. Therefore, the hybrid EF-1 not only preserves the individual properties of the parent peptides, but also acquires the ability to disrupt Gram-negative bacterial membrane. Meanwhile, such an expression system can reduce both the time and cost for large-scale peptide production, which ensures its potential application at the industrial level.
Subject(s)
Anti-Infective Agents/pharmacology , Bacteria/drug effects , Gene Expression , Peptide Elongation Factor 1/genetics , Peptide Elongation Factor 1/pharmacology , Peptides/genetics , Peptides/pharmacology , Pichia/genetics , Recombinant Proteins , Anti-Infective Agents/isolation & purification , Bacteria/metabolism , Bacteria/ultrastructure , Cell Membrane Permeability/drug effects , Dose-Response Relationship, Drug , Microbial Sensitivity Tests , Peptide Elongation Factor 1/chemistry , Peptide Elongation Factor 1/isolation & purification , Peptides/isolation & purificationABSTRACT
Intestinal inflammatory disorders, such as inflammatory bowel disease, are major contributors to mortality and morbidity in humans and animals worldwide. While some native peptides have great potential as therapeutic agents against intestinal inflammation, potential cytotoxicity, anti-inciting action, and suppression of anti-inflammatory activity may limit their development as anti-inflammatory agents. Peptide hybridization is an effective approach for the design and engineering of novel functional peptides because hybrid peptides combine the advantages and benefits of various native peptides. In the present study, a novel hybrid anti-inflammatory peptide that combines the active center of Cecropin A (C) and the core functional region of LL-37 (L) was designed [C-L peptide; C (1-8)-L (17-30)] through in silico analysis to reduce cytotoxicity and improve the anti-inflammatory activity of the parental peptides. The resulting C-L peptide exhibited lower cytotoxicity than either C or L peptides alone. C-L also exerted a protective effect against lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 macrophages and in the intestines of a mouse model. The hybrid peptide exhibited increased anti-inflammatory activity compared to the parental peptides. C-L plays a role in protecting intestinal tissue from damage, LPS-induced weight loss, and leukocyte infiltration. In addition, C-L reduces the expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), IL-1ß, and interferon-gamma (IFN-γ), as well as reduces cell apoptosis. It also reduced mucosal barrier damage caused by LPS. The anti-inflammatory effects of the hybrid peptide were mainly attributed to its LPS-neutralizing activity and antagonizing the activation of LPS-induced Toll-like receptor 4-myeloid differentiation factor 2 (TLR4/MD2). The peptide also affected the TLR4-(nuclear factor κB) signaling pathway, modulating the inflammatory response upon LPS stimulation. Collectively, these findings suggest that the newly designed peptide, C-L, could be developed into a novel anti-inflammatory agent for animals or humans.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Inflammation/drug therapy , Intestinal Mucosa/drug effects , Peptides/pharmacology , Animals , Antimicrobial Cationic Peptides/pharmacology , Cell Line , Inflammation/chemically induced , Inflammation/metabolism , Interleukin-6/metabolism , Intestinal Mucosa/metabolism , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred C57BL , Mucous Membrane/drug effects , Mucous Membrane/metabolism , NF-kappa B/metabolism , RAW 264.7 Cells , Signal Transduction/drug effects , Toll-Like Receptor 4/metabolism , Tumor Necrosis Factor-alpha/metabolismABSTRACT
The aim was to enhance production of functional hydrolysate from wheat bran (WB). WB was hydrolyzed with 3000 U/mL É-amylase and 1200 U/mL alkaline protease to prepare WB insoluble dietary fibre (WBIDF). Functional hydrolysate production from the extract containing crude xylan of WBIDF by xylanase was optimized by Taguchi method. The optimal condition for xylan degradation and functional substances production was 78.50 U/mL xylanase, pH 10.0, 50 °C, and reaction time 6 h. The maximum yield of reducing sugars was 614.0 µg/mL, xylobiose increased from 12.9 µg/mL to 213.3 µg/mL, xylotriose increased from 34.9 µg/mL to 174.0 µg/mL, ferulic acid 13.1 µg/mL made up 57.5 % of the total identifiable phenolic pool in the hydrolysate. The total antioxidant activity of hydrolysate was 141.8 mg ascorbic acid equivalents g-1 crude xylan, and the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity reached 92.7 %. The hydrolysate exhibited great potential in agricultural and food industry application.
ABSTRACT
Intestinal inflammation can cause impaired epithelial barrier function and disrupt immune homeostasis, which increases the risks of developing many highly fatal diseases. Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes intestinal infections worldwide and is a major pathogen that induces intestinal inflammation. Various antibacterial peptides have been described as having the potential to suppress and treat pathogen-induced intestinal inflammation. Cecropin A (1-8)-LL37 (17-30) (C-L), a novel hybrid peptide designed in our laboratory that combines the active center of C with the core functional region of L, shows superior antibacterial properties and minimized cytotoxicity compared to its parental peptides. Herein, to examine whether C-L could inhibit pathogen-induced intestinal inflammation, we investigated the anti-inflammatory effects of C-L in EHEC O157:H7-infected mice. C-L treatment improved the microbiota composition and microbial community balance in mouse intestines. The hybrid peptide exhibited improved anti-inflammatory effects than did the antibiotic, enrofloxacin. Hybrid peptide treated infected mice demonstrated reduced clinical signs of inflammation, reduced weight loss, reduced expression of pro-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interferon-gamma (IFN-γ)], reduced apoptosis, and reduced markers of jejunal epithelial barrier function. The peptide also affected the MyD88-nuclear factor κB signaling pathway, thereby modulating inflammatory responses upon EHEC stimulation. Collectively, these findings suggest that the novel hybrid peptide C-L could be developed into a new anti-inflammatory agent for use in animals or humans.