Peptidoglycan recognition proteins（PGRPs） are a family of pattern recognition receptors（PRRs） of the immune system,which bind and hydrolyze bacterial peptidoglycan.Here,a long type PGRP（PGRP-L） was first cloned ...Peptidoglycan recognition proteins（PGRPs） are a family of pattern recognition receptors（PRRs） of the immune system,which bind and hydrolyze bacterial peptidoglycan.Here,a long type PGRP（PGRP-L） was first cloned in the lower vertebrate species Xenopus tropicalis（Xt）.The XtPGRP-L possessed a conserved genomic structure with five exons and four introns.The alignment and phylogenetic analysis indicated that XtPGRP-L might be a type of amidase-like PGRP.The 3-D model showed that XtPGRP-L possessed a conserved structure compared with the Drosophila PGRP-Lb.During embryonic development,XtPGRP-L was not expressed until the 72 h tadpole stage.In adult tissues,it was strongly expressed in the liver,lung,intestine,and stomach.Furthermore,after LPS stimulation,the expression of XtPGRP-L was up-regulated significantly in the liver,intestine and spleen,indicating that XtPGRP-L may play an important role in the innate immunity of Xenopus tropicalis.展开更多
INTRODUCTIONBifidobacteria are physiologically beneficial bacteria which are perdominant in human intestine ,and possess the most important functions .They play an important role in maintaining microbial balance of th...INTRODUCTIONBifidobacteria are physiologically beneficial bacteria which are perdominant in human intestine ,and possess the most important functions .They play an important role in maintaining microbial balance of the intestine .Furthermore , their presence is thought to be an important indication of health of the body [1-4].Whole peptidoglycan ( WPG) is the major component in the cell wall of bifidobacterium ,which is also a biological responsemodifier with nontoxic side dffcets.展开更多
AIM： To analyze the distinct immune responses induced by Lactobacillus peptidoglycan （PG）. METHODS： BALB/c mice were intraperitoneally injected with PG once a day for three consecutive days, Peritoneal macrophage ...AIM： To analyze the distinct immune responses induced by Lactobacillus peptidoglycan （PG）. METHODS： BALB/c mice were intraperitoneally injected with PG once a day for three consecutive days, Peritoneal macrophage and splenocyte mRNA was extracted and the gene expression profile was studied using high-density oligonudeotide microarrays. Inhibitory effects of Lactobacillus PG on colon tumor tissue were studied in vitro and in vivo, RESULTS： The gene expression profiles revealed that the TLR-NF-kB and Jak-STAT signaling pathways were highly activated. An inflammatory phenotype was induced when peritoneal macrophages were initially exposed to Lactobacillus PG and switched to a more complex phenotype when BALB/c mice were treated with three doses of Lactobacillus PG. A protective physiological inflammatory response was induced after three consecutive days of PG treatment. It was tending toward Thl dominant immune response. Lactobacillus PG also appeared to induce a significant in vivo anti-colon tumor effect. CONCLUSION： Lactobacillus PG is responsible for certain immune responses induced by Lactobacilli. Anti-tumor effects of Lactobacilliare likely to attribute to the activation of macrophages by PG expressed on the bacterial cell surface.展开更多
Objective: To explore the antitumor mechanisms of whole peptidoglycan of bifidobacterium. Methods: The apoptotic cells and the positive expression of bcl-2 and bax oncoprotein were studied nude mice transplantation tu...Objective: To explore the antitumor mechanisms of whole peptidoglycan of bifidobacterium. Methods: The apoptotic cells and the positive expression of bcl-2 and bax oncoprotein were studied nude mice transplantation tumors of colorectal carcinoma by employing in situ end labeling technique and immunohistochemical staining. Results: The apoptotic cell density, the positive rate and the staining intensity of bax oncoprotein of the transplantation tumor of colorectal carcinoma in the whole peptidoglycan injection group were significantly higher when compared with the tumor control group. The positive rate of bcl-2 oncoportein in the whole peptidoglycan injection group was obviously lower than that in the tumor control group (P<0.01). Conclusion: Whole peptidoglycan of Bifidobacterium bifidum could induce cell apoptosis of nude mice transplantation tumors of colorectal carcinoma by down-regulating the expression of the bcl-2 gene and upregulating the expression of the bax gene.展开更多
Two homogeneous new peptidoglycans were obtained from Lycium barbarum L. Theywere found to be effective ingredients capable of resining lipid peroxidation. The componentsand linkages of the two homogeneous polysacchar...Two homogeneous new peptidoglycans were obtained from Lycium barbarum L. Theywere found to be effective ingredients capable of resining lipid peroxidation. The componentsand linkages of the two homogeneous polysaccharides were studied by means of complete acidhydrolysis, periodate oxidation. Smith degradation enzyme hydrolysis, IR, GC and aminoacid analysis. Homogeneous polysaccharide LBPC2 was found to be a β(1→4)(1→6) peptidoglycanwith MW of 1.2×104, composed of Xyl, Rha. Man in a molar ratio of8.8:2.3;1, LBPC4 was foundto be a a(1→4)(1→6) peptidoglycan with MW of 1.0×104, composed of glucans.展开更多
The effects of different hydrolysis methods on peptidoglycan （PG） were assessed in terms of their impact on the innate immunity and disease resistance of Pacific white shrimp, Litopenaeus vannamei. PG derived from B...The effects of different hydrolysis methods on peptidoglycan （PG） were assessed in terms of their impact on the innate immunity and disease resistance of Pacific white shrimp, Litopenaeus vannamei. PG derived from Bifidobacteriurn thermophilum was prepared in the laboratory and processed with lysozyme and protease under varying conditions to produce several different PG preparations. A standard shrimp feed was mixed with 0.05% PG preparations to produce a number of experimental diets for shrimp. The composition, concentration, and molecular weight ranges of the soluble PG were analyzed. Serum phenoloxidase and acid phosphatase activity in the shrimp were determined on Days 6-31 of the experiment. The protective activity of the PG preparations was evaluated by exposing shrimp to white spot syndrome virus （WSSV）. Data on the composition of the PG preparations indicated that preparations hydrolyzed with lysozyme for 72 h had more low-molecular-weight PG than those treated for 24 h, and hydrolysis by protease enhanced efficiency of hydrolysis compared to lysozyme. SDS-PAGE showed changes in the molecular weight of the soluble PG produced by the different hydrolysis methods. Measurements of serum phenoloxidase and acid phosphatase activity levels in the shrimp indicated that the PG preparations processed with enzymes were superior to the preparation which had not undergone hydrolysis in enhancing the activity of the two serum enzymes. In addition, the preparation containing more low-molecular-weight PG enhanced the resistance of the shrimp to WSSV, whereas no increased resistance was observed for preparations containing less low-molecular-weight PG. These findings suggest that the immunity-enhancing activity of PG is related to its molecular weight and that increasing the quantity of low-molecular-weight PG can fortify the effect of immunity enhancement.展开更多
Objective: To explore the functions of whole peptidoglycan (WPG ) of bifidobacterium in regulating immune reactions. Methods: IL- 1 activity produced by peritoneal macrophages was investigated by murine thymocyte prol...Objective: To explore the functions of whole peptidoglycan (WPG ) of bifidobacterium in regulating immune reactions. Methods: IL- 1 activity produced by peritoneal macrophages was investigated by murine thymocyte proliferating method; The content of IL-6 and IL-12 was detected by ELISA. Results: IL--1 activity and the contents of IL--6 and IL--12 secreted by peritoneal macrophages of nude mice in the WPG injection group were significantly higher than those in the control group (P < 0. 01 ). Conclusion: WPG of bifidobacteria can activate peritoneal macrophages to secret relatively large amount of IL- 1. IL- 6 and IL- 12.展开更多
Nitric oxide (NO) plays a pivotal role in main- taining balance of physiological events in many systems including the autonomic, cardiovas- cular, hematological, and pulmonary systems. Lipopolysaccharide (LPS) and pep...Nitric oxide (NO) plays a pivotal role in main- taining balance of physiological events in many systems including the autonomic, cardiovas- cular, hematological, and pulmonary systems. Lipopolysaccharide (LPS) and peptidoglycan (PGN), components of the outer cell membranes of Gram-negative bacteria and cell walls of Gram-positive bacteria respectively, are in- criminated in NO-induced septic shock. Ne- bivolol is a third generation β1- adrenoceptor blocker with a vasodilatory property attributed to enhanced availability of nitric oxide and re- duction of cellular oxidative stress through an unknown mechanism. The current study ex- plored the hypothesis that if nebivolol enhances the availability of NO, pretreatment with ne- bivolol may enhance production of NO in re- sponse to subsequent treatment with LPS and PGN, an observation that may have relevance in clinical septic shock. Groups of female BALB/c mice each containing 12 mice (6-8 weeks old) were injected intraperitoneally with LPS (30 μg/mouse), PGN (100 μg/mouse), nebivolol (0.25 μg/g, 0.35 μg/g, 0.7 μg/g), LPS and nebivolol (0.25 μg/g), LPS and nebivolol (0.35 μg/g), LPS and nebivolol (0.7 μg/g), PGN and nebivolol (0.25 μg/g), PGN and nebivolol (0.35μg/g). One group of mice was injected with saline and an- other served as control. Three mice from each group were bled 1, 3, 6 and 9 hours post-injec- tion, the blood was pooled and the nitrite serum levels, reflecting NO concentration, were de- termined using Greiss reagent. The following results were obtained: 1) Treatment with saline did not induce NO production;2) LPS induced NO production to a maximal limit of 545% at 9 hours as compared to treatment with saline;3) PGN did not induce NO production;4) nebivolol at most doses and periods (7 out of 10 deter- minations) increased NO production over a range of 18-110% as compared to treatment with saline;5) Nebivolol enhanced LPS-induced production of NO by 58% at a dose of 0.7 μg/gm at 9 hours. It is concluded that nebivolol in- duces NO production. At low doses nebivolol initially appeared to have a suppressive or no effect on NO production induced by LPS. In- crease in the dose of nebivolol resulted in augmentation of LPS-induced production of NO. PGN, in the dose tested, did not have an effect on NO production.展开更多
Peptidoglycan(PG),the essential exoskeleton in most bacteria,is synthesized through the action of bacterial transglycosylases(TGases),positioning these enzymes as elegant and desirable targets for antibiotic discovery...Peptidoglycan(PG),the essential exoskeleton in most bacteria,is synthesized through the action of bacterial transglycosylases(TGases),positioning these enzymes as elegant and desirable targets for antibiotic discovery.This review covers the major TGases involved in PG biogenesis,including TGases from the glycosyltransferase family 51(GT51)and the newly discovered shape,elongation,division,sporulation(SEDS)family.We discuss the distinct roles of these two TGases during PG synthesis and emphasize the structural and catalytic differences,highlighting their coordination in PG assembly.Moreover,we summarize recent advances in TGase-involved antimicrobial strategies,including substrate-mimicking TGase inhibitors,PG terminators,and TGase-related immunological therapy targeting TGase from the GT51 family,and the first non-substrate-like TGase inhibitor against the SEDS protein.These valuable insights pave the way for the further development of novel TGase-related antimicrobial agents.展开更多
Tetrodotoxin(TTX)is a potent neurotoxin found in nature,the possible presence of TTX in pufferfish ovaries,liver,and other processing waste poses a serious environmental and safety hazard.Lactic acid bacteria(LAB)was ...Tetrodotoxin(TTX)is a potent neurotoxin found in nature,the possible presence of TTX in pufferfish ovaries,liver,and other processing waste poses a serious environmental and safety hazard.Lactic acid bacteria(LAB)was found to be able to remove a variety of harmful substances,however,its elimination action and mechanism on Trx is not clear.In this study,the removal effects of different states(activated,inactivated,and fragmented LABs)of three LAB strains on TTX amount and toxicity were tested and compared.It was found that thermal inactivated LABs had the best effect,which could reduce the TTX amount by 49.0%-60.33%and decrease the toxicity of TTX by 57.0%-83.67%.In addition,peptidoglycan(PG)of three strains of LABs was found to be a key component in the removal of TTX,which could decrease the toxicity of TTx by more than 87.0%.By analyzing the changes of functional groups of PGs,zeta-potential and binding effect between PG and TTX before and after the masking of carboxyl or amino groups of PGs,it was found that the removal effect of PG to TTX was significantly decreased(>55.0%)when the carboxyl or amino groups of PGs were masked.At the same time,the zeta-potential of PG combined with TTX was also decreased.These results suggested that the amino and carboxyl groups of PGs were important action sites for the binding interaction between LAB and TTX,and electrostatic interaction might be one of the ways of binding between PG and TTX.Our study could provide a scientific supporting on the removal action mechanism research of PG to TTX.展开更多
Peptidoglycan recognition protein(PGRP)plays a vital role in invertebrate innate immunity system as a specific pattern recognition receptor for peptidoglycan.Bivalves possess various PGRP systems for self-defense;howe...Peptidoglycan recognition protein(PGRP)plays a vital role in invertebrate innate immunity system as a specific pattern recognition receptor for peptidoglycan.Bivalves possess various PGRP systems for self-defense;however,it has not been characterized in razor clam Sinonovacula constricta.In this study,eight PGRP coding sequences were identified and analyzed from S.constricta genome,which are designated as ScPGRP-S1,ScPGRP-S2,ScPGRP-S3,ScPGRP-S4,ScPGRP-S5,ScPGRP-S6,ScPGRP-S7,ScPGRP-S8.The results of molecular evolutionary analyses showed that all eight ScPGRP genes were highly conserved and exhi-bited a typical PGRP/amidase_2 domain as PGRP genes in other mollusks.Moreover,the presence of signal peptides was predicted in ScPGRP-S2,ScPGRP-S3 and ScPRP-S6,while a transmembrane structure only existed in ScPGRP-S6.Notably,a tertiary struc-ture analysis indicated that no disulfide bond was observed in ScPGRP-S5 and ScPGRP-S7.The mRNA transcripts analysis of ScPGRPs revealed that the high expression patterns of ScPGRP-S1 and ScPGRP-S4 were found in mantle,adductor muscle and foot,while those of ScPGRP-S2,ScPGRP-S3 and ScPGRP-S6 were observed in hepatopancreas.Furthermore,the temporal expression profiles of ScPGRPs in the hepatopancreas were analyzed by qPCR<https://www.sciencedirect.com/topics/immunology-and-microbiology/real-time-polymerase-chain-reaction>after Gram-negative Vibrio parahaemolyticus and Gram-positive Staphylococcus aureus challenges.The mRNA expressions of ScPGRP-S2,ScPGRP-S3 and ScPGRP-S6 could be induced by V.pa-rahaemolyticus and S.aureus.Overall,our findings indicated that ScPGRPs were involved in the immune defense against invaders,which constituted a comprehensive understanding of the potential role of PGRP genes in S.constricta.展开更多
The emergence of microbial drug resistance,coupled with the paucity of new antibiotics poses an impending threat to public health.In this work,we drew inspiration from synthetic peptidoglycan oligomers and successfull...The emergence of microbial drug resistance,coupled with the paucity of new antibiotics poses an impending threat to public health.In this work,we drew inspiration from synthetic peptidoglycan oligomers and successfully constructed antibody-recruiting peptidoglycan analogs,2a-d,with excellent safety profiles and high efficiencies in recruiting antibodies across different conditions.Further,we demonstrated that these peptidoglycan analogs could be readily incorporated into bacteria cell walls,whereby both simple monoclonal and pooled human serum antibodies effectively congregated to the surfaceengineered bacteria,leading to the complete extermination of the engineered bacterial cells both in vitro and in vivo.Our peptidoglycan analog agents for recruiting endogenous antibodies to combat pathogenic bacteria enable further development of promising broad-spectrum immunotherapeutics.展开更多
Understanding bacterial strategies for coping with heavy metal stress is essential for elucidating their resilience in contaminated environments.However,whether cell wall exfoliation contributes to bacterial tolerance...Understanding bacterial strategies for coping with heavy metal stress is essential for elucidating their resilience in contaminated environments.However,whether cell wall exfoliation contributes to bacterial tolerance under heavy metal stress,such as cadmium(Cd)exposure,remains unclear and requires further investigation.In this study,we reveal a novel self-protective mechanism in Stenotrophomonas sp.H225 isolated from a Cd-contaminated farmland soil,which underwent controlled cell wall exfoliation and regeneration in response to Cd stress up to 200 mg L^(-1).Transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that the exfoliated cell wall fragments served as extracellular Cd sinks,thereby reducing intracellular Cd accumulation.Fourier-transform infrared spectroscopy and enzyme-linked immunosorbent assay indicated progressive peptidoglycan(PG)degradation,with exfoliated PG concentration in solution increasing from 148 ng mL^(-1) at 0 mg L^(-1) Cd to 240 ng mL^(-1) at 200 mg L^(-1) Cd.This degradation was counteracted by the compensatory upregulation of PG biosynthesis genes,with the enrichment ratio reaching up to 0.83,facilitating cell wall reconstruction.Transcriptomic analysis and gene knockout experiments identified mtgA(encoding a monofunctional transglycosylase)as a key determinant in cell wall repair and Cd resistance.To our knowledge,this is the first mechanistic evidence that bacteria can mitigate heavy metal toxicity through dynamic cell wall remodeling involving exfoliation and regeneration.This finding enhances our understanding of microbial survival strategies under environmental stress and highlights potential targets for engineering metal-tolerant strains for bioremediation applications.展开更多
Peptidoglycan recognition proteins （PGRPs） are a family of innate immune receptors that specifically recognize peptidoglycans （PGNs） on the surface of a number of pathogens. Here, we have identified and characteri...Peptidoglycan recognition proteins （PGRPs） are a family of innate immune receptors that specifically recognize peptidoglycans （PGNs） on the surface of a number of pathogens. Here, we have identified and characterized six PGRPs from endoparasitoid wasp, Microplitis mediator （MmePGRPs）. To understand the roles of PGRPs in parasitoid wasps, we analyzed their evolutionary relationship and orthology, expression profiles during different developmental stages, and transcriptional expression following infection with Gram-positive and -negative bacteria and a fungus. MmePGRP-S1 was significantly induced in response to pathogenic infection. This prompted us to evaluate the effects of RNA interference mediated gene specific knockdown ofMmePGRP-S1. The knockdown of MmePGRP-S1 （iMmePGRP-S1） dramatically affected wasps＇ survival following challenge by Micrococcus luteus, indicating the involvement of this particular PGRP in immune responses against Gram-positive bacteria. This action is likely to be mediated by the Toll pathway, but the mechanism remains to be determined. MmePGRP-S 1 does not play a significant role in anti-fungal immunity as indicated by the survival rate of iMmePGRP-S wasps. This study provides a comprehensive characterization of PGRPs in the economically important hymenopteran species M. mediator.展开更多
基金supported by the Project from the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (10KJB240001)the Foundation for Talent Recruitment of Yancheng Institute of Technology (XKR2011007)the National Natural Science Foundation of China (30830083)
文摘Peptidoglycan recognition proteins（PGRPs） are a family of pattern recognition receptors（PRRs） of the immune system,which bind and hydrolyze bacterial peptidoglycan.Here,a long type PGRP（PGRP-L） was first cloned in the lower vertebrate species Xenopus tropicalis（Xt）.The XtPGRP-L possessed a conserved genomic structure with five exons and four introns.The alignment and phylogenetic analysis indicated that XtPGRP-L might be a type of amidase-like PGRP.The 3-D model showed that XtPGRP-L possessed a conserved structure compared with the Drosophila PGRP-Lb.During embryonic development,XtPGRP-L was not expressed until the 72 h tadpole stage.In adult tissues,it was strongly expressed in the liver,lung,intestine,and stomach.Furthermore,after LPS stimulation,the expression of XtPGRP-L was up-regulated significantly in the liver,intestine and spleen,indicating that XtPGRP-L may play an important role in the innate immunity of Xenopus tropicalis.
基金Supported by the Natural Science Foundation of Guangdong Province,No.994066
文摘INTRODUCTIONBifidobacteria are physiologically beneficial bacteria which are perdominant in human intestine ,and possess the most important functions .They play an important role in maintaining microbial balance of the intestine .Furthermore , their presence is thought to be an important indication of health of the body [1-4].Whole peptidoglycan ( WPG) is the major component in the cell wall of bifidobacterium ,which is also a biological responsemodifier with nontoxic side dffcets.
基金Supported by the PhD Programs Foundation of Ministry of Education of China, No. 20040295005
文摘AIM： To analyze the distinct immune responses induced by Lactobacillus peptidoglycan （PG）. METHODS： BALB/c mice were intraperitoneally injected with PG once a day for three consecutive days, Peritoneal macrophage and splenocyte mRNA was extracted and the gene expression profile was studied using high-density oligonudeotide microarrays. Inhibitory effects of Lactobacillus PG on colon tumor tissue were studied in vitro and in vivo, RESULTS： The gene expression profiles revealed that the TLR-NF-kB and Jak-STAT signaling pathways were highly activated. An inflammatory phenotype was induced when peritoneal macrophages were initially exposed to Lactobacillus PG and switched to a more complex phenotype when BALB/c mice were treated with three doses of Lactobacillus PG. A protective physiological inflammatory response was induced after three consecutive days of PG treatment. It was tending toward Thl dominant immune response. Lactobacillus PG also appeared to induce a significant in vivo anti-colon tumor effect. CONCLUSION： Lactobacillus PG is responsible for certain immune responses induced by Lactobacilli. Anti-tumor effects of Lactobacilliare likely to attribute to the activation of macrophages by PG expressed on the bacterial cell surface.
文摘Objective: To explore the antitumor mechanisms of whole peptidoglycan of bifidobacterium. Methods: The apoptotic cells and the positive expression of bcl-2 and bax oncoprotein were studied nude mice transplantation tumors of colorectal carcinoma by employing in situ end labeling technique and immunohistochemical staining. Results: The apoptotic cell density, the positive rate and the staining intensity of bax oncoprotein of the transplantation tumor of colorectal carcinoma in the whole peptidoglycan injection group were significantly higher when compared with the tumor control group. The positive rate of bcl-2 oncoportein in the whole peptidoglycan injection group was obviously lower than that in the tumor control group (P<0.01). Conclusion: Whole peptidoglycan of Bifidobacterium bifidum could induce cell apoptosis of nude mice transplantation tumors of colorectal carcinoma by down-regulating the expression of the bcl-2 gene and upregulating the expression of the bax gene.
文摘Two homogeneous new peptidoglycans were obtained from Lycium barbarum L. Theywere found to be effective ingredients capable of resining lipid peroxidation. The componentsand linkages of the two homogeneous polysaccharides were studied by means of complete acidhydrolysis, periodate oxidation. Smith degradation enzyme hydrolysis, IR, GC and aminoacid analysis. Homogeneous polysaccharide LBPC2 was found to be a β(1→4)(1→6) peptidoglycanwith MW of 1.2×104, composed of Xyl, Rha. Man in a molar ratio of8.8:2.3;1, LBPC4 was foundto be a a(1→4)(1→6) peptidoglycan with MW of 1.0×104, composed of glucans.
基金Supported by the National Basic Research Program of China (973 Program)(No.2012CB114405)
文摘The effects of different hydrolysis methods on peptidoglycan （PG） were assessed in terms of their impact on the innate immunity and disease resistance of Pacific white shrimp, Litopenaeus vannamei. PG derived from Bifidobacteriurn thermophilum was prepared in the laboratory and processed with lysozyme and protease under varying conditions to produce several different PG preparations. A standard shrimp feed was mixed with 0.05% PG preparations to produce a number of experimental diets for shrimp. The composition, concentration, and molecular weight ranges of the soluble PG were analyzed. Serum phenoloxidase and acid phosphatase activity in the shrimp were determined on Days 6-31 of the experiment. The protective activity of the PG preparations was evaluated by exposing shrimp to white spot syndrome virus （WSSV）. Data on the composition of the PG preparations indicated that preparations hydrolyzed with lysozyme for 72 h had more low-molecular-weight PG than those treated for 24 h, and hydrolysis by protease enhanced efficiency of hydrolysis compared to lysozyme. SDS-PAGE showed changes in the molecular weight of the soluble PG produced by the different hydrolysis methods. Measurements of serum phenoloxidase and acid phosphatase activity levels in the shrimp indicated that the PG preparations processed with enzymes were superior to the preparation which had not undergone hydrolysis in enhancing the activity of the two serum enzymes. In addition, the preparation containing more low-molecular-weight PG enhanced the resistance of the shrimp to WSSV, whereas no increased resistance was observed for preparations containing less low-molecular-weight PG. These findings suggest that the immunity-enhancing activity of PG is related to its molecular weight and that increasing the quantity of low-molecular-weight PG can fortify the effect of immunity enhancement.
文摘Objective: To explore the functions of whole peptidoglycan (WPG ) of bifidobacterium in regulating immune reactions. Methods: IL- 1 activity produced by peritoneal macrophages was investigated by murine thymocyte proliferating method; The content of IL-6 and IL-12 was detected by ELISA. Results: IL--1 activity and the contents of IL--6 and IL--12 secreted by peritoneal macrophages of nude mice in the WPG injection group were significantly higher than those in the control group (P < 0. 01 ). Conclusion: WPG of bifidobacteria can activate peritoneal macrophages to secret relatively large amount of IL- 1. IL- 6 and IL- 12.
文摘Nitric oxide (NO) plays a pivotal role in main- taining balance of physiological events in many systems including the autonomic, cardiovas- cular, hematological, and pulmonary systems. Lipopolysaccharide (LPS) and peptidoglycan (PGN), components of the outer cell membranes of Gram-negative bacteria and cell walls of Gram-positive bacteria respectively, are in- criminated in NO-induced septic shock. Ne- bivolol is a third generation β1- adrenoceptor blocker with a vasodilatory property attributed to enhanced availability of nitric oxide and re- duction of cellular oxidative stress through an unknown mechanism. The current study ex- plored the hypothesis that if nebivolol enhances the availability of NO, pretreatment with ne- bivolol may enhance production of NO in re- sponse to subsequent treatment with LPS and PGN, an observation that may have relevance in clinical septic shock. Groups of female BALB/c mice each containing 12 mice (6-8 weeks old) were injected intraperitoneally with LPS (30 μg/mouse), PGN (100 μg/mouse), nebivolol (0.25 μg/g, 0.35 μg/g, 0.7 μg/g), LPS and nebivolol (0.25 μg/g), LPS and nebivolol (0.35 μg/g), LPS and nebivolol (0.7 μg/g), PGN and nebivolol (0.25 μg/g), PGN and nebivolol (0.35μg/g). One group of mice was injected with saline and an- other served as control. Three mice from each group were bled 1, 3, 6 and 9 hours post-injec- tion, the blood was pooled and the nitrite serum levels, reflecting NO concentration, were de- termined using Greiss reagent. The following results were obtained: 1) Treatment with saline did not induce NO production;2) LPS induced NO production to a maximal limit of 545% at 9 hours as compared to treatment with saline;3) PGN did not induce NO production;4) nebivolol at most doses and periods (7 out of 10 deter- minations) increased NO production over a range of 18-110% as compared to treatment with saline;5) Nebivolol enhanced LPS-induced production of NO by 58% at a dose of 0.7 μg/gm at 9 hours. It is concluded that nebivolol in- duces NO production. At low doses nebivolol initially appeared to have a suppressive or no effect on NO production induced by LPS. In- crease in the dose of nebivolol resulted in augmentation of LPS-induced production of NO. PGN, in the dose tested, did not have an effect on NO production.
基金supported by the Ministry of Education(MOE-T2EP30120-0007)the Nanyang Technological University,Singapore(RG107/23).
文摘Peptidoglycan(PG),the essential exoskeleton in most bacteria,is synthesized through the action of bacterial transglycosylases(TGases),positioning these enzymes as elegant and desirable targets for antibiotic discovery.This review covers the major TGases involved in PG biogenesis,including TGases from the glycosyltransferase family 51(GT51)and the newly discovered shape,elongation,division,sporulation(SEDS)family.We discuss the distinct roles of these two TGases during PG synthesis and emphasize the structural and catalytic differences,highlighting their coordination in PG assembly.Moreover,we summarize recent advances in TGase-involved antimicrobial strategies,including substrate-mimicking TGase inhibitors,PG terminators,and TGase-related immunological therapy targeting TGase from the GT51 family,and the first non-substrate-like TGase inhibitor against the SEDS protein.These valuable insights pave the way for the further development of novel TGase-related antimicrobial agents.
基金supported by a grant from the National Natural Science Foundation of China[NO.32172324].
文摘Tetrodotoxin(TTX)is a potent neurotoxin found in nature,the possible presence of TTX in pufferfish ovaries,liver,and other processing waste poses a serious environmental and safety hazard.Lactic acid bacteria(LAB)was found to be able to remove a variety of harmful substances,however,its elimination action and mechanism on Trx is not clear.In this study,the removal effects of different states(activated,inactivated,and fragmented LABs)of three LAB strains on TTX amount and toxicity were tested and compared.It was found that thermal inactivated LABs had the best effect,which could reduce the TTX amount by 49.0%-60.33%and decrease the toxicity of TTX by 57.0%-83.67%.In addition,peptidoglycan(PG)of three strains of LABs was found to be a key component in the removal of TTX,which could decrease the toxicity of TTx by more than 87.0%.By analyzing the changes of functional groups of PGs,zeta-potential and binding effect between PG and TTX before and after the masking of carboxyl or amino groups of PGs,it was found that the removal effect of PG to TTX was significantly decreased(>55.0%)when the carboxyl or amino groups of PGs were masked.At the same time,the zeta-potential of PG combined with TTX was also decreased.These results suggested that the amino and carboxyl groups of PGs were important action sites for the binding interaction between LAB and TTX,and electrostatic interaction might be one of the ways of binding between PG and TTX.Our study could provide a scientific supporting on the removal action mechanism research of PG to TTX.
基金supported by the National Key Research and Development Program of China(No.2018YFD0901405)the Zhejiang Major Program of Science and Technology(No.2016C02055-9)+1 种基金the Ningbo Major Project of Science and Technology(No.2019B10005)the China Agriculture Research System of MOF and MARA,National Marine Genetic Resource Center Program.
文摘Peptidoglycan recognition protein(PGRP)plays a vital role in invertebrate innate immunity system as a specific pattern recognition receptor for peptidoglycan.Bivalves possess various PGRP systems for self-defense;however,it has not been characterized in razor clam Sinonovacula constricta.In this study,eight PGRP coding sequences were identified and analyzed from S.constricta genome,which are designated as ScPGRP-S1,ScPGRP-S2,ScPGRP-S3,ScPGRP-S4,ScPGRP-S5,ScPGRP-S6,ScPGRP-S7,ScPGRP-S8.The results of molecular evolutionary analyses showed that all eight ScPGRP genes were highly conserved and exhi-bited a typical PGRP/amidase_2 domain as PGRP genes in other mollusks.Moreover,the presence of signal peptides was predicted in ScPGRP-S2,ScPGRP-S3 and ScPRP-S6,while a transmembrane structure only existed in ScPGRP-S6.Notably,a tertiary struc-ture analysis indicated that no disulfide bond was observed in ScPGRP-S5 and ScPGRP-S7.The mRNA transcripts analysis of ScPGRPs revealed that the high expression patterns of ScPGRP-S1 and ScPGRP-S4 were found in mantle,adductor muscle and foot,while those of ScPGRP-S2,ScPGRP-S3 and ScPGRP-S6 were observed in hepatopancreas.Furthermore,the temporal expression profiles of ScPGRPs in the hepatopancreas were analyzed by qPCR<https://www.sciencedirect.com/topics/immunology-and-microbiology/real-time-polymerase-chain-reaction>after Gram-negative Vibrio parahaemolyticus and Gram-positive Staphylococcus aureus challenges.The mRNA expressions of ScPGRP-S2,ScPGRP-S3 and ScPGRP-S6 could be induced by V.pa-rahaemolyticus and S.aureus.Overall,our findings indicated that ScPGRPs were involved in the immune defense against invaders,which constituted a comprehensive understanding of the potential role of PGRP genes in S.constricta.
基金the Ministry of Education(grant nos.MOET2EP30120-0007 and MOE2018-T2-2-128)the National Research Foundation(grant no.NRF-CRP22-2019-0002)+3 种基金Agency for Science,Technology and Research(A*STAR)Singapore(grant no.A20E5c0087)the National Natural Science Foundation of China(grant no.32300033)the Scientific Research Foundation of Hainan University(grant nos.KYQD(ZR)-22173 and KYQD(ZR)-23006).
文摘The emergence of microbial drug resistance,coupled with the paucity of new antibiotics poses an impending threat to public health.In this work,we drew inspiration from synthetic peptidoglycan oligomers and successfully constructed antibody-recruiting peptidoglycan analogs,2a-d,with excellent safety profiles and high efficiencies in recruiting antibodies across different conditions.Further,we demonstrated that these peptidoglycan analogs could be readily incorporated into bacteria cell walls,whereby both simple monoclonal and pooled human serum antibodies effectively congregated to the surfaceengineered bacteria,leading to the complete extermination of the engineered bacterial cells both in vitro and in vivo.Our peptidoglycan analog agents for recruiting endogenous antibodies to combat pathogenic bacteria enable further development of promising broad-spectrum immunotherapeutics.
基金partially supported by the National Natural Science Foundation of China (Nos. 42377004 and 41991334)the Fundamental Research Funds for the Central Universities (No. 226-2025-0004)+1 种基金the China Agriculture Research System (No. CARS-01)the opportunity granted by the China Scholarship Council (No. 202406320448)
文摘Understanding bacterial strategies for coping with heavy metal stress is essential for elucidating their resilience in contaminated environments.However,whether cell wall exfoliation contributes to bacterial tolerance under heavy metal stress,such as cadmium(Cd)exposure,remains unclear and requires further investigation.In this study,we reveal a novel self-protective mechanism in Stenotrophomonas sp.H225 isolated from a Cd-contaminated farmland soil,which underwent controlled cell wall exfoliation and regeneration in response to Cd stress up to 200 mg L^(-1).Transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that the exfoliated cell wall fragments served as extracellular Cd sinks,thereby reducing intracellular Cd accumulation.Fourier-transform infrared spectroscopy and enzyme-linked immunosorbent assay indicated progressive peptidoglycan(PG)degradation,with exfoliated PG concentration in solution increasing from 148 ng mL^(-1) at 0 mg L^(-1) Cd to 240 ng mL^(-1) at 200 mg L^(-1) Cd.This degradation was counteracted by the compensatory upregulation of PG biosynthesis genes,with the enrichment ratio reaching up to 0.83,facilitating cell wall reconstruction.Transcriptomic analysis and gene knockout experiments identified mtgA(encoding a monofunctional transglycosylase)as a key determinant in cell wall repair and Cd resistance.To our knowledge,this is the first mechanistic evidence that bacteria can mitigate heavy metal toxicity through dynamic cell wall remodeling involving exfoliation and regeneration.This finding enhances our understanding of microbial survival strategies under environmental stress and highlights potential targets for engineering metal-tolerant strains for bioremediation applications.
基金Acknowledgments This work was supported by National Basic Research Program of China （No. 2014CB138405）, Strategic Priority Research Program of CAS （No. XDB 11030600）, National Natural Science Foundation of China （No. 31472008, 31401804, 31272497）, Open Research Fund Program of State Key Laboratory of Integrated Pest Management （Chinese IPM1407, 1304）.
文摘Peptidoglycan recognition proteins （PGRPs） are a family of innate immune receptors that specifically recognize peptidoglycans （PGNs） on the surface of a number of pathogens. Here, we have identified and characterized six PGRPs from endoparasitoid wasp, Microplitis mediator （MmePGRPs）. To understand the roles of PGRPs in parasitoid wasps, we analyzed their evolutionary relationship and orthology, expression profiles during different developmental stages, and transcriptional expression following infection with Gram-positive and -negative bacteria and a fungus. MmePGRP-S1 was significantly induced in response to pathogenic infection. This prompted us to evaluate the effects of RNA interference mediated gene specific knockdown ofMmePGRP-S1. The knockdown of MmePGRP-S1 （iMmePGRP-S1） dramatically affected wasps＇ survival following challenge by Micrococcus luteus, indicating the involvement of this particular PGRP in immune responses against Gram-positive bacteria. This action is likely to be mediated by the Toll pathway, but the mechanism remains to be determined. MmePGRP-S 1 does not play a significant role in anti-fungal immunity as indicated by the survival rate of iMmePGRP-S wasps. This study provides a comprehensive characterization of PGRPs in the economically important hymenopteran species M. mediator.
