Cationic antimicrobial peptides （AMPs） are considered as important candidate therapeutic agents, which exert potent microbicidal properties against bacteria, fungi and some viruses. Based on our previous findings ki...Cationic antimicrobial peptides （AMPs） are considered as important candidate therapeutic agents, which exert potent microbicidal properties against bacteria, fungi and some viruses. Based on our previous findings king cobra cathelicidin （OH-CATH） is a 34-amino acid peptide that exerts strong antibacterial and weak hemolytic activity. The aim of this research is to evaluate the efficacy of both OH-CATH30 and its analog D-OH-CATH30 against clinical isolates comparing with routinely utilized antibiotics in vitro. In this study, 584 clinical isolates were tested （spanning 2013-2016） and the efficacy of the candidate peptides and antibiotics were determined by a broth microdilution method according to the CLSI guidelines. Among the 584 clinical isolates, 85% were susceptible to OH-CATH30 and its analogs. Both L- and D-OH-CATH30 showed higher efficacy against （toward） Gram-positive bacteria and stronger antibacterial activity against nearly all Gram-negative bacteria tested compare with antibiotics. The highest bactericidal activity was detected against Acinetobacter spp., including multi-drug-resistant Acinetobacter baumannfi （MRAB） and methicillin-resistant Staphylococcus aureus （MRSA）. The overall efficacy of OH-CATH30 and its analogs was higher than that of the 9 routinely used antibiotics. OH-CATH30 is a promising candidate drug for the treatment of a wide variety of bacterial infections which are resistant to many routinely used antimicrobial agents.展开更多
Vitamin A and its biologically active derivative,retinoic acid(RA),are important for many immune processes.RA,in particular,is essential for the development of immune cells,including neutrophils,which serve as a front...Vitamin A and its biologically active derivative,retinoic acid(RA),are important for many immune processes.RA,in particular,is essential for the development of immune cells,including neutrophils,which serve as a front-line defense against infection.Although vitamin A deficiency has been linked to higher susceptibility to infections,the precise role of vitamin A/RA in host-pathogen interactions remains poorly understood.Here,we provided evidence that RA boosts neutrophil killing of methicillin-resistant Staphylococcus aureus(MRSA).RA treatment stimulated primary human neutrophils to produce reactive oxygen species,neutrophil extracellular traps and the antimicrobial peptide cathelicidin(LL-37).Because RA treatment was insufficient to reduce MRSA burden in an in vivo murine model of skin infection,we expanded our analysis to other infectious agents.RA did not affect the growth of a number of common bacterial pathogens,including MRSA,Escherichia coli K1 and Pseudomonas aeruginosa;however,RA directly inhibited the growth of group A Streptococcus(GAS).This antimicrobial effect,likely in combination with RA-mediated neutrophil boosting,resulted in substantial GAS killing in neutrophil killing assays conducted in the presence of RA.Furthermore,in a murine model of GAS skin infection,topical RA treatment showed therapeutic potential by reducing both skin lesion size and bacterial burden.These findings suggest that RA may hold promise as a therapeutic agent against GAS and perhaps other clinically significant human pathogens.展开更多
Background:LL-37 peptide is a member of the human cathelicidin family,and has been shown to promote the healing of pressure ulcers.However,the low stability of this peptide within the wound environment limits its clin...Background:LL-37 peptide is a member of the human cathelicidin family,and has been shown to promote the healing of pressure ulcers.However,the low stability of this peptide within the wound environment limits its clinical use.Chitosan(CS)hydrogel is commonly used as a base material for wound dressing material.Methods:CS hydrogel(2.5%w/v)was encapsulated with LL-37.Cytotoxicity of the product was examined in cultured NIH3 T3 fibroblasts.Effects on immune response was examined by measuring tumor necrosis factor-α(TNF-α)release from RAW 264.7 macrophages upon exposure to lipopolysaccharides.Antibacterial activity was assessed using Staphylococcus aureus.Potential effect on pressure ulcers was examined using a mouse model.Briefly,adult male C57 BL/6 mice were subjected to skin pressure using magnets under a 12/12 h schedule for 21 days.Mice were randomized to receive naked LL-37(20μg),chitosan gel containing 20μg LL-37(LL-37/CS hydrogel)or hydrogel alone under the ulcer bed(n=6).A group of mice receiving no intervention was also included as a control.Results:LL-37/CS hydrogel did not affect NIH3 T3 cell viability.At a concentration of 1–5μg/ml,LL-37/CS inhibited TNF-αrelease from macrophage.At 5μg/ml,LL-37/CS inhibited the growth of Staphylococcus aureus.The area of the pressure ulcers was significantly lower in mice receiving LL-37/CS hydrogel in comparison to all other 3 groups on days 11(84.24%±0.25%),13(56.22%±3.91%)and 15(48.12%±0.28%).Histological examination on days 15 and 21 showed increased epithelial thickness and density of newly-formed capillary with naked LL-37 and more so with LL-37/CS.The expression of key macromolecules in the process of angiogenesis(i.e.,hypoxia inducible factor-1α(HIF-1α)and vascular endothelial growth factor-A(VEGF-A))in wound tissue was increased at both the mRNA and protein levels.Conclusion:Chitosan hydrogel encapsulated with LL-37 is biocompatible and could promote the healing of pressure ulcers.展开更多
Antimicrobial peptides（AMPs）,a class of gene-encoded peptides,are the first line of immune system to defense microbial invasions in multicellular organisms.Cathelicidins are an important family of AMPs that have bee...Antimicrobial peptides（AMPs）,a class of gene-encoded peptides,are the first line of immune system to defense microbial invasions in multicellular organisms.Cathelicidins are an important family of AMPs that have been identified exclusively in vertebrates.However,up to now,cathelicidins from amphibians are poorly understood.In the present study,we reported the identification and characterization of two novel cathelicidins（FM-CATH1 and FMCATH2） from the frog Fejervarya multistriata.The c DNA sequences encoding FM-CATHs were successfully cloned from the constructed lung c DNA library of F.multistriata.Both of the c DNA sequences encoding FM-CATHs are 447 bp in length,and the deduced mature peptides of FM-CATHs are composed of 34 residues.Structural analysis indicated that FM-CATH1 and FM-CATH2 mainly assume amphipathic alpha-helical conformations.Antimicrobial and bacterial killing kinetic analysis indicated that both FM-CATH1 and FM-CATH2 possess potent,broad-spectrum and rapid antimicrobial potency.And cytoplasmic membrane permeabilization analysis indicated that FM-CATH1 and FMCATH2 kill bacteria by inducing the permeabilization of bacterial membrane.Besides direct antimicrobial activities,FM-CATHs also exhibited significant inhibitory effect on the formation of bacterial biofilms at low concentrations below 1×MIC.Furthermore,FM-CATH1 and FM-CATH2 exhibited potent anti-inflammatory activities by inhibiting LPS-induced transcription and production of pro-inflammatory cytokines TNF-α,IL-1β,and IL-6 in mouse peritoneal macrophages.Meanwhile,FM-CATHs showed relatively low cytotoxic activity against mammalian normal and tumor cell lines,and low hemolytic activity against human erythrocytes.In summary,the identification of FM-CATHs provides novel clues for our understanding of the roles of cathelicidins in amphibian immune systems.The potent antimicrobial,biofilm inhibitory,anti-inflammatory activities,and low cytotoxicity of FM-CATHs imply their great potential in novel antibiotics development.展开更多
基金supported by grants from the National Natural Sciences Foundation of China(31572268,31560596)the Key Research Program of the Chinese Academy of Sciences(KJZD-EW-L03)+3 种基金"Yunnan Scholar"Programthe Yunnan Applied Basic Research Projects(2016FD076)the National Training Program of Innovation and Entrepreneurship for Undergraduates(201510685001201610685001)Puer University(RCXM003&CXTD011)
文摘Cationic antimicrobial peptides （AMPs） are considered as important candidate therapeutic agents, which exert potent microbicidal properties against bacteria, fungi and some viruses. Based on our previous findings king cobra cathelicidin （OH-CATH） is a 34-amino acid peptide that exerts strong antibacterial and weak hemolytic activity. The aim of this research is to evaluate the efficacy of both OH-CATH30 and its analog D-OH-CATH30 against clinical isolates comparing with routinely utilized antibiotics in vitro. In this study, 584 clinical isolates were tested （spanning 2013-2016） and the efficacy of the candidate peptides and antibiotics were determined by a broth microdilution method according to the CLSI guidelines. Among the 584 clinical isolates, 85% were susceptible to OH-CATH30 and its analogs. Both L- and D-OH-CATH30 showed higher efficacy against （toward） Gram-positive bacteria and stronger antibacterial activity against nearly all Gram-negative bacteria tested compare with antibiotics. The highest bactericidal activity was detected against Acinetobacter spp., including multi-drug-resistant Acinetobacter baumannfi （MRAB） and methicillin-resistant Staphylococcus aureus （MRSA）. The overall efficacy of OH-CATH30 and its analogs was higher than that of the 9 routinely used antibiotics. OH-CATH30 is a promising candidate drug for the treatment of a wide variety of bacterial infections which are resistant to many routinely used antimicrobial agents.
基金US National Institutes of Health grants(R01-AI145325 to VN and R37-AI052453 to VN and RLG)a BioLegend Graduate Fellowship in Immunology.
文摘Vitamin A and its biologically active derivative,retinoic acid(RA),are important for many immune processes.RA,in particular,is essential for the development of immune cells,including neutrophils,which serve as a front-line defense against infection.Although vitamin A deficiency has been linked to higher susceptibility to infections,the precise role of vitamin A/RA in host-pathogen interactions remains poorly understood.Here,we provided evidence that RA boosts neutrophil killing of methicillin-resistant Staphylococcus aureus(MRSA).RA treatment stimulated primary human neutrophils to produce reactive oxygen species,neutrophil extracellular traps and the antimicrobial peptide cathelicidin(LL-37).Because RA treatment was insufficient to reduce MRSA burden in an in vivo murine model of skin infection,we expanded our analysis to other infectious agents.RA did not affect the growth of a number of common bacterial pathogens,including MRSA,Escherichia coli K1 and Pseudomonas aeruginosa;however,RA directly inhibited the growth of group A Streptococcus(GAS).This antimicrobial effect,likely in combination with RA-mediated neutrophil boosting,resulted in substantial GAS killing in neutrophil killing assays conducted in the presence of RA.Furthermore,in a murine model of GAS skin infection,topical RA treatment showed therapeutic potential by reducing both skin lesion size and bacterial burden.These findings suggest that RA may hold promise as a therapeutic agent against GAS and perhaps other clinically significant human pathogens.
基金supported by the National Natural Science Foundation of China(No.81701838)the China Postdoctoral Science Foundation(2018M632628)
文摘Background:LL-37 peptide is a member of the human cathelicidin family,and has been shown to promote the healing of pressure ulcers.However,the low stability of this peptide within the wound environment limits its clinical use.Chitosan(CS)hydrogel is commonly used as a base material for wound dressing material.Methods:CS hydrogel(2.5%w/v)was encapsulated with LL-37.Cytotoxicity of the product was examined in cultured NIH3 T3 fibroblasts.Effects on immune response was examined by measuring tumor necrosis factor-α(TNF-α)release from RAW 264.7 macrophages upon exposure to lipopolysaccharides.Antibacterial activity was assessed using Staphylococcus aureus.Potential effect on pressure ulcers was examined using a mouse model.Briefly,adult male C57 BL/6 mice were subjected to skin pressure using magnets under a 12/12 h schedule for 21 days.Mice were randomized to receive naked LL-37(20μg),chitosan gel containing 20μg LL-37(LL-37/CS hydrogel)or hydrogel alone under the ulcer bed(n=6).A group of mice receiving no intervention was also included as a control.Results:LL-37/CS hydrogel did not affect NIH3 T3 cell viability.At a concentration of 1–5μg/ml,LL-37/CS inhibited TNF-αrelease from macrophage.At 5μg/ml,LL-37/CS inhibited the growth of Staphylococcus aureus.The area of the pressure ulcers was significantly lower in mice receiving LL-37/CS hydrogel in comparison to all other 3 groups on days 11(84.24%±0.25%),13(56.22%±3.91%)and 15(48.12%±0.28%).Histological examination on days 15 and 21 showed increased epithelial thickness and density of newly-formed capillary with naked LL-37 and more so with LL-37/CS.The expression of key macromolecules in the process of angiogenesis(i.e.,hypoxia inducible factor-1α(HIF-1α)and vascular endothelial growth factor-A(VEGF-A))in wound tissue was increased at both the mRNA and protein levels.Conclusion:Chitosan hydrogel encapsulated with LL-37 is biocompatible and could promote the healing of pressure ulcers.
基金supported by the grants BK20160336 from the Natural Science Foundation of Jiangsu Province to Yan CHEN16KJB350004 from the Natural Science Foundation of College in Jiangsu Province to Yipeng WANG+1 种基金SYN201407 and SYN201504 from the Suzhou Science and Technology Development Project to Yipeng WANG2015NY06 from the Haimen Science and Technology Development Project to Yipeng WANG
文摘Antimicrobial peptides（AMPs）,a class of gene-encoded peptides,are the first line of immune system to defense microbial invasions in multicellular organisms.Cathelicidins are an important family of AMPs that have been identified exclusively in vertebrates.However,up to now,cathelicidins from amphibians are poorly understood.In the present study,we reported the identification and characterization of two novel cathelicidins（FM-CATH1 and FMCATH2） from the frog Fejervarya multistriata.The c DNA sequences encoding FM-CATHs were successfully cloned from the constructed lung c DNA library of F.multistriata.Both of the c DNA sequences encoding FM-CATHs are 447 bp in length,and the deduced mature peptides of FM-CATHs are composed of 34 residues.Structural analysis indicated that FM-CATH1 and FM-CATH2 mainly assume amphipathic alpha-helical conformations.Antimicrobial and bacterial killing kinetic analysis indicated that both FM-CATH1 and FM-CATH2 possess potent,broad-spectrum and rapid antimicrobial potency.And cytoplasmic membrane permeabilization analysis indicated that FM-CATH1 and FMCATH2 kill bacteria by inducing the permeabilization of bacterial membrane.Besides direct antimicrobial activities,FM-CATHs also exhibited significant inhibitory effect on the formation of bacterial biofilms at low concentrations below 1×MIC.Furthermore,FM-CATH1 and FM-CATH2 exhibited potent anti-inflammatory activities by inhibiting LPS-induced transcription and production of pro-inflammatory cytokines TNF-α,IL-1β,and IL-6 in mouse peritoneal macrophages.Meanwhile,FM-CATHs showed relatively low cytotoxic activity against mammalian normal and tumor cell lines,and low hemolytic activity against human erythrocytes.In summary,the identification of FM-CATHs provides novel clues for our understanding of the roles of cathelicidins in amphibian immune systems.The potent antimicrobial,biofilm inhibitory,anti-inflammatory activities,and low cytotoxicity of FM-CATHs imply their great potential in novel antibiotics development.
