Protective effect and mechanism of nanoantimicrobial peptide ND-C14 against Streptococcus pneumoniae infection / 世界急诊医学杂志（英文）

@#BACKGROUND: Streptococcus pneumoniae (S. pneumoniae) is a common pathogen that causes bacterial pneumonia. However, with increasing bacterial resistance, there is an urgent need to develop new drugs to treat S. pneumoniae infections. Nanodefensin with a 14-carbon saturated fatty acid (ND-C14) is a novel nanoantimicrobial peptide designed by modifying myristic acid at the C-terminus of human α-defensin 5 (HD5) via an amide bond. However, it is unclear whether ND-C14 is effective against lung infections caused by S. pneumoniae. METHODS: In vitro, three groups were established, including the control group, and the HD5 and ND-C14 treatment groups. A virtual colony-count assay was used to evaluate the antibacterial activity of HD5 and ND-C14 against S. pneumoniae. The morphological changes of S. pneumoniae treated with HD5 or ND-C14 were observed by scanning electron microscopy. In vivo, mice were divided into sham, vehicle, and ND-C14 treatment groups. Mice in the sham group were treated with 25 µL of phosphate-buffered saline (PBS). Mice in the vehicle and ND-C14 treatment groups were treated with intratracheal instillation of 25 µL of bacterial suspension with 2×108 CFU/mL (total bacterial count: 5×106 CFU), and then the mice were given 25 μL PBS or intratracheally injected with 25 μL of ND-C14 (including 20 µg or 50 µg), respectively. Survival rates were evaluated in the vehicle and ND-C14 treatment groups. Bacterial burden in the blood and bronchoalveolar lavage fluid were counted. The lung histology of the mice was assessed. A propidium iodide uptake assay was used to clarify the destructive effect of ND-C14 against S. pneumoniae. RESULTS: Compared with HD5, ND-C14 had a better bactericidal effect against S. pneumoniae because of its stronger ability to destroy the membrane structure of S. pneumoniae in vitro. In vivo, ND-C14 significantly delayed the death time and improved the survival rate of mice infected with S. pneumoniae. ND-C14 reduced bacterial burden and lung tissue injury. Moreover, ND-C14 had a membrane permeation effect on S. pneumoniae, and its destructive ability increased with increasing ND-C14 concentration.

Application and prospect of artificial intelligence in antimicrobial peptides screening / 中国药科大学学报

@#Antimicrobial peptides (AMPs) are a class of small molecule peptides with broad-spectrum antimicrobial activity.Their unique antimicrobial mechanism can effectively treat infectious diseases, with rare drug resistance.However, though AMPs with antimicrobial activity can be screened by traditional methods, the whole process is complicated.The artificial intelligence (AI) screening method is faster and more convenient, with great potential in exploring new natural antimicrobial peptides.In this paper, strategies related to AMPs screening by AI were summarized and compared, including data sources applied to model training, artificial intelligence machine model and omics data applied to model screening of novel antimicrobial peptides.The application prospects and advantages were reviewed, in hope of providing new ideas for identification, research and development of antimicrobial peptides.

Antimicrobial peptide for bacterial infection imaging: first case reported in Brazil

ABSTRACT Molecular imaging markers can be used to differentiate between infection and aseptic inflammation, determine the severity of infection, and monitor treatment responses. One of these markers is ubiquicidin(29-41) (UBI), a cationic peptide fragment that binds to the bacterial membrane wall and is labeled with gallium-68 (68Ga), a positron emitter radioisotope. The use of UBI in positron emission tomography (PET)/computed tomography (CT) for improved detection of lesions has been receiving considerable attention recently. Herein, we report the first case of 68Ga-UBI PET/CT performed in Brazil. The patient was a 39-year-old woman referred for a scan to confirm a clinical suspicion of chronic osteomyelitis of her fractured left tibia. PET images revealed radiotracer uptake near the posterior contour of the tibial fracture focus and the fixation plate, in the soft tissue around the distal half of the tibia, and in the non-consolidated fracture of the left distal fibula. Surgery for local cleaning was performed, and culture of a specimen collected from the surgical site confirmed the presence of Staphylococcus aureus. In the present case, 68Ga-UBI PET/CT, a non-invasive imaging modality, identified the infection foci in vivo, indicating its potential for clinical use.

Research progress on antibacterial peptides Epinecidin-1 / 药学实践杂志

The antimicrobial peptide Epinecidin-1 is a kind of small molecule active peptides extracted from Epinephelus coioides，which serves as the first line of defense for innate immune defense system of Epinephelus coioides against various pathogens. In vitro and in vivo studies have confirmed that the antimicrobial peptide Epinecidin-1 not only exhibits broad-spectrum anti-pathogen activities (including bacteria, fungi, viruses, and parasites, etc.), but also has pharmacological activities such as immune regulation, anti-cancer and wound healing. In this paper, the relevant research on the antimicrobial peptide Epinecidin-1 in recent years were summarized, including its mechanism of action, pharmacological activities, potential limitations and application prospects , so as to provide information for further research.

Establishment of mouse pancreatic ductal organoids and exploration of its physiological functions / 中华胰腺病杂志

Objective:To establish culture system for mouse pancreatic ductal organoids and investigate the morphology and physiological functions of the organoids.Methods:Pancreatic tissues were taken from C57BL/6 mice (6-8 weeks) and digested by collagenase Ⅳ. The pancreatic ducts were separated and collected and then the pancreatic organoids were cultured in the complete medium after Matrix gel embedding. Morphological evaluation of the organoids was performed after hematoxylin-eosin staining. The expression and localization of markers for organoids were identified by Western Blot and immunofluorescence staining; and the expression and localization of ion channels and antimicrobial peptides of the organoids were detected by agarose gel electrophoresis and immunofluorescence staining.Results:Mouse pancreatic organoids were successfully established, which could be stably passaged for 10 generations. The organoids grew spherically and formed a duct-like structure. The internal cavity corresponded to the lumen of pancreatic duct tissue. The pancreatic organoids stably expressed stem progenitor cell marker gene SOX9 and ductal epithelial cell-specific gene KRT19, which were both localized in the epithelium. The organoids did not express amylase. The organoids maintained stable expression of epithelial ion channels Clcn1, Kcnma1, CFTR, Slc12a5, Slc26a3, Slc26a6 and Scnn1a, low expression of Ano1 and no expression of Clcn3, Kcna1, Kcna2, Kcnd3, Kcnh1, Atp12a, Slc4a4, Slc9a1, Slc12a2 and Slc26a11; and CFTR highly expressed in epithelial cells. The organoids maintained high expression of antimicrobial peptides Reg3a, CRAMP and glycoprotein 2, low expression of Defb1, Defb2, and Defb3 and no expression of Defa1 and Defa4; and both CRAMP and Reg3a were expressed in the epithelial cells and secreted into the lumen of the organoids.Conclusions:Mouse pancreatic organoids are successfully established, which can be stably passaged. The organoids maintain the characteristics of ductal epithelial cells and can be used as an in vitro model to study the physiology of pancreatic ducts.

Mecanismos inmunológicos en Cnidaria: un sistema inmune basal de gran complejidad e interés bioprospectivo / Immunological mechanisms in Cnidaria: A highly complex basal immune system with bioprospective interest

Introducción: La protección ante agentes biológicos propios y externos de los cnidarios dependen de la inmunidad innata, la cual consta de tres procesos inmunológicos principales: 1) reconocimiento inmunológico, 2) señalización intracelular, y 3) respuesta efectora. Objetivo: Revisar críticamente el conocimiento actual del repertorio molecular involucrado en la respuesta inmune en cnidarios, así como, su papel en el establecimiento de la simbiosis, y las posibles aplicaciones biotecnológicas de las moléculas involucradas en el proceso de inmunidad. Métodos: Se realizó una revisión de artículos científicos encontrados a través de las bases de datos del NCBI, Google Scholar y Scielo, con palabras claves como inmunidad y/o reconocimiento inmunológico en cnidarios, en una ventana de tiempo de la última década, sin descartar literatura clásica más antigua. Resultados: El reconocimiento inmunológico consiste en receptores inmunológicos que reconocen patrones moleculares e inducen respuestas efectoras como la movilización de moléculas al sitio de la infección, la ingestión microbiana y la formación de moléculas que activan cascadas de señalización. La fase de señalización involucra mediadores de la traducción de señales que activan genes de trascripción, y cascadas de señalización intracelular que inician respuestas de defensa adecuadas. Las respuestas efectoras incluyen la capa superficial del mucus, péptidos antimicrobianos, especies reactivas de oxígeno y la respuesta celular mediada por fagocitosis. Por último, se presenta un esquema y una tabla integral de las vías de respuesta inmune en los cnidario. Conclusiones: La inmunidad en Cnidaria está mediada por mecanismos de defensa complejos integrados por receptores de reconocimiento de patógenos, vías de señalización intracelular, células y moléculas efectoras encargadas de la eliminación del patógeno, y reconocimiento-aceptación de simbiontes. El estudio de compuestos activos del sistema inmune en Cnidaria ha sido poco explorado, sin embargo, el trabajo realizado con otros compuestos presentes en las toxinas de este filo, los sitúa como una fuente importante de moléculas antimicrobianas dignas de un análisis de bioprospección.

Introduction: Cnidarians depend on innate immunity for protection against both their own and external biological agents. It consists of three main immunological processes: 1) immune recognition, 2) intracellular signaling, and 3) effector response. Objective: To critically review current knowledge of the molecular repertoire involved in the immune response in cnidarians, its role in symbiosis, and possible biotechnological applications. Methods: We used keywords such as immunity, and immunological recognition in cnidarians, in the NCBI, Scielo and Google Scholar databases, for the last decade. Results: Cnidarian immune recognition consists of molecular pattern receptors and responses such as the mobilization of molecules to the site of infection, microbial ingestion, and the formation of molecules that activate signaling cascades. The signaling phase involves translation mediators that activate transcriptional genes and intracellular signaling cascades that initiate defenses. Effector responses include surface layer mucus, antimicrobial peptides, reactive oxygen species, and the cellular response mediated by phagocytosis. Conclusions: Immunity in Cnidaria is mediated by complex defense mechanisms composed of pathogen recognition receptors, intracellular signaling pathways, effector cells and molecules responsible for pathogen elimination, and recognition of symbionts. There is a potential for toxin compounds useful as antimicrobial molecules.

Molecular design and biological activity analysis of antimicrobial peptide RIKL / 生物工程学报

Natural antimicrobial peptides have strong bactericidal activities. An obstacle of the development of antimicrobial peptides resides in the difficulty of developing peptides with high biocompatibility. In this study, molecular dynamics analysis was employed to assess the structural characteristics and biological activities of peptides. A (RXKY)2(YRY)2 structure was used as a template to design an antimicrobial peptide RIKL of high-efficiency and low-toxicity, where X represents Ile and Y represents Leu. The secondary structure of the antimicrobial peptide was detected by circular dichroism (CD), and the structures of RIKL in water and in POPC/POPG membrane environment were measured using molecular dynamics. The biological activity of RIKL was further studied by assessing its antimicrobial activity, hemolytic activity, eukaryotic cytotoxicity, and salt ion stability. CD results showed that RIKL presented an α-helical structure in a simulated bacterial membrane environment. Molecular dynamics simulation predicted that the secondary structure of RIKL could be partly retained in water and POPG environment, while this secondary structure was weakened in the POPC environment. Antimicrobial test suggested that RIKL had high antimicrobial activities, and the geometric mean of the Minimum Inhibitory Concentration (MIC) was 3.1 μmol/L. The hemolysis indicated that RIKL had no hemolytic activity within the detection range, and cytotoxicity test suggested the cytotoxicity of RIKL was low. Stability test showed that RIKL maintained antimicrobial activities under different pH, serum concentrations and salt environments. Based on the above results, RIKL has high cell selectivity and has the potential as a highly effective antibacterial drug.

Effect of catheterin-related antimicrobial peptides on the high glucose induced cardiac microvascular endothelial cell injury / 中华老年医学杂志

Objective:To investigate the effect of catheterin-related antimicrobial peptides(CRAMP)on the damage of cardiac microvascular endothelial cells induced by high glucose.Methods:Adult mouse heart microvascular endothelial cells were isolated and cultured.A model of microvascular endothelial cell injury was established by high glucose culture.The endothelial cells were randomly divided into 4 groups as the following.In the control group, 27.5 mmol/L mannitol was given as isoosmotic control as compared with the high glucose group.In the high glucose group(HG group), cells were cultured with 33.3 mmol/L high glucose for 48 h, and then treated without CRAMP.In 0.15 mg/L CRAMP treatment group, cells were cultured with 33.3 mmol/L high glucose for 48 h, followed by 0.15 mg/L CRAMP treatmen for 24 h. In the 0.5 mg/L CRAMP treatment group, cells were cultured with 33.3 mmol/L high glucose treatment for 48 h, and then treated with 0.5 mg/L CRAMP for 24 h. Cell proliferation was examined by staining with CKK-8 cell counting kit.The secretion of inflammatory factors in microvascular endothelial cells was detected by ELISA kit.Reactive oxygen species assay kit detects the level of reactive oxygen species in cells.Cell apoptosis was detected by apoptosis kit.Tubule formation and tubule number were measured by cells cultured on the matrix glue membrane, then detected by microscopic observation.The nitric oxide(NO)test kit measures levels of NO.The expression of nitric oxide synthase(eNOS)was detected by western blotting.Results:The cell proliferation activity was significant lower in the HG group than in control group[(52.2±5.4)% vs.(100.0±7.3)%]. The cell proliferation activity was higher in the 0.15 and 0.5 mg/L CRAMP groups than in the HG group[(72.0±3.4)% vs.(52.2±5.4)%; and(84.2±5.8)% vs.(52.2±5.4)%( F=75.300, P<0.001)]. The expression of tumor necrosis factor-α was significantly higher in the HG group than in the control group and in 0.5 mg/L CRAMP group[HG group of(239.1±32.1)μg/L, the control of(22.1±3.7)μg/L, 0.5 mg/L CRAMP of(84.6±9.4)μg/L]( F=197.300, P<0.001). The level of reactive oxygen species was significantly higher in the HG group than in control group and in 0.5 mg/L CRAMP group[(20.8±2.4)in HG group, (4.8±1.7)in control group, (10.2±1.5)in CRAMP group]( F=105.700, P<0.001). The number of apoptotic cells was significantly higher in the HG group than in control group and in 0.5 mg/L CRAMP group[(21.2±3.1)% in HG group, (2.2±0.6)% in control group(9.5±1.2)% in CRAMP group]( F=141.900, P<0.001). The length and number of tubules were lower in the HG group than in control group and in CRAMP group[for the length: (87.8±9.1)μm in HG group, (337.0±37.2)μm in control group(206.5±16.3)μm in CRAMP group( F=160.800, P<0.001); for the number: (9.1±1.9)in HG group, (22.0±3.4)in control group, (16.8±2.2)]in CRAMP group( F=36.200, P<0.001)]. The level of NO was lower in the HG group than in control group and in CRAMP group[(0.25±0.05)in HG group, (1.05±0.16)in control group, (0.75±0.06)in CRAMP group( F=83.200, P<0.001)]. The protein expression and mRNA levels of endothelial nitric oxide synthase(eNOS)were lower in the HG group than in the control group and in CRAMP group[for eNOS protein: (0.07±0.03)in HG group, (0.81±0.05)in control group, (0.54±0.07)in CRAMP group, F=275.700, P<0.001; and for eNOS mRNA: (0.11±0.07)in HG group, (1.00±0.22)in control group, (0.57±0.12)in CRAMP group, F=50.600, P<0.001]. Conclusions:CRAMP protein can inhibit the damage of cardiac microvascular endothelial cells by increasing eNOS-mediated NO signal pathway.

Defensin c-thionin from Capsicum chinense improves butyrate cytotoxicity on human colon adenocarcinoma cell line Caco-2

BACKGROUND: Butyrate is a histone deacetylase inhibitor that induces apoptosis and inhibits cell proliferation of colorectal cancer cells. To improve its anticancer activity, butyrate has been evaluated mixed with drugs and different molecules. Plant antimicrobial peptides are attractive anticancer alternative molecules because they show selective cytotoxic activity against different cancer cell lines. In this work, we explore if the plant defensin c-thionin (Capsicum chinense) can improve butyrate activity on Caco-2 cell line and we also determined the mechanism of death activated. RESULTS: The combined treatment of c-thionin (3.5 mM) and butyrate (50 mM) showed higher cytotoxicity on Caco-2 cells with respect to single treatments. Also, the combined treatment reduced cell proliferation and exhibited a higher rate of apoptosis than single treatments. Combined treatment induced caspases 8 and 9 activation to an extent comparable with that of butyrate while c-thionin did not activate caspases. Additionally, reactive oxygen species generation preceded the onset of apoptosis, and superoxide anion production was higher in cells treated with the combined treatment. CONCLUSIONS: The c-thionin from Habanero chili pepper improved the butyrate cytotoxicity on Caco-2 cells. This effect occurred through apoptosis induction associated with reactive oxygen species production. Therefore, the combination of butyrate with cytotoxic antimicrobial peptides could be an attractive strategy for cancer therapy.

Association of salivary physicochemical characteristics and peptide levels with dental caries in children

Aim: The purpose of this investigation was to evaluate the association of physicochemical properties and antimicrobial peptide levels of saliva with caries activity in children. Materials and Methods: The required volume of unstimulated saliva was collected from 41 children aged 3–12 years with no systemic diseases. Caries activity was calculated using DMFS and dmfs records for each participating child. Collected saliva samples were then examined for their flow rate, pH, and buffering capacity. The concentration of three peptides was assessed including LL-37, human neutrophil peptide (HNP) 1–3, and human beta-defensin (HBD)-3 through an enzyme-linked immunosorbent assay. The correlation between caries activity score (CAS) and salivary variables was looked using the linear regression and Spearman's correlation method. The comparison of CAS means between high- and low-value groups of salivary items was performed using independent sample t-test while the association of CAS and salivary parameters in categorical scale was tested by Chi-square test. Results: No statistically significant differences were found between the CAS means at low and high categories of each salivary physicochemical parameter and those of antimicrobial peptides. There was a negative correlation between HNP1–3 and CAS and also between HBD-3 and CAS, but these results were not statistically meaningful. High HNP1–3 concentration was noted in 67% of the low caries rate group and 29% of the high caries rate group, with a statistically significant difference between the low and high caries rate groups (P = 0.019). Conclusion: Salivary inherent factors are not dominant determinants in caries activity. The current results may suggest that ?-defensins (HNP1–3) have a protective role against dental caries.

Cambios en el perfil protéico de E. coli O157:H7 frente al tratamiento con Ib-M1 e IONP@Ib-M1 / Changes in the protein profile of E. coli O157: H7 against treatment with Ib-M1 and IONP@Ib-M1 / Identificação de alterações no perfil protetor de E. coli O157: H7 contra o tratamento com Ib-M1 e IONP@Ib-M1

Resumen Escherichia coli 0157:H7 es una bacteria patógena reconocida por su capacidad de resistencia a diversos antibióticos; razón por la cual, se generan complicaciones en el tratamiento de infecciones producidas por esta bacteria. El péptido Ib-M1 y el bioconjugado I0NP@Ib-M1 han surgido como una nueva alternativa antimicrobiana contra E. coli 0157:H7. El mecanismo de acción de Ib-Mi e I0NP@Ib-M1 contra esta bacteria aún es desconocido; por lo tanto, el objetivo de esta investigación fue identificar el cambio en el perfil de proteínas de E. coli 0157:H7 luego del tratamiento con Ib-M1 e I0NP@ Ib-M1 como primer paso para determinar su mecanismo de acción. Para esto, se llevó a cabo la obtención de proteínas, posteriormente se realizó una electroforesis bidimensional para finalmente realizar la determinación de la variabilidad de los perfiles proteicos. Una vez obtenidos estos perfiles, se llevó a cabo un análisis de varianza (AN0VA). Se identificaron 72 proteínas expresadas diferencialmente, las cuales pueden relacionarse con el efecto sobre el crecimiento de la bacteria en presencia de Ib-M1 e I0NP@Ib-M. Estas proteínas se encuentran involucradas en procesos de transferencia de grupos acilo (proteína Yhbs), translocación de lipoproteínas (proteína LolA) y transporte de aminoácidos (proteína GpmA), entre otros.

Abstract Escherichia coli 0157: H7 is a pathogenic bacterium which is recognized for the ability to resist multiple antibiotics; accordingly, complications occur in the treatment of infections caused by this bacterium. The Ib-M1 peptide and the I0NP @ Ib-M1 bioconjugate have emerged as a new antimicrobial alternatives against E. coli 0157: H7. The mechanism of action of Ib-M1 and I0NP @ Ib-M1 against this bacterium is still unknown; therefore, the goal of this research was to identify the change in the proteins profile of E. coli 0157: H7 after treatment with Ib-M1 and I0NP @ Ib-M1 as a first step to determine its mechanism of action. For this, the proteins were obtained first, and then a two-dimensional electrophoresis was performed to finally determine the variability of the protein profiles. 0nce the protein profiles were obtained, an analysis of variance (AN0VA) was carried out. 72 differentially expressed proteins were identified, which can be connected to the effect on the bacterium's growth in the presence of Ib-M1 and I0NP @ Ib-M. These proteins are involved in acyl groups transfer processes (Yhbs protein), lipoprotein translocation (LolA protein) and amino acid transport (GpmA protein), among others.

Resumo Escherichia coli O157: H7 é uma bactéria patogênica reconhecida por sua capacidade de resistir a vários antibióticos; razão pela qual, complicações são geradas no tratamento de infecções produzidas por essa bactéria. O peptídeo Ib-M1 livre e imobilizado em nanopartículas magnéticas de óxido de ferro (IONP @ Ib-M1) surgiu como uma nova alternativa antimicrobiana contra E. coli O157: H7 e isolados clínicos desta bactéria. O mecanismo de ação de Ib-M1 e IONP @ Ib-M1 contra E. coli O157: H7 ainda é desconhecido; Portanto, o objetivo desta pesquisa foi identificar a alteração no perfil proteico de E. coli O157: H7 após o tratamento com Ib-M1 e IONP @ Ib-M1 como um primeiro passo para determinar seu mecanismo de ação. Para isso, foi realizada a obtenção das proteínas, posteriormente foi realizada uma eletroforese bidimensional para finalmente determinar a variabilidade dos perfis protéicos. Uma vez obtidos os perfis de proteínas, foi realizada uma análise de variância (ANOVA). Os resultados mostram a identificação de proteínas expressas diferencialmente e que estão envolvidas em processos de transferência de grupos acila (proteína Yhbs), translocação de lipoproteínas (proteína LolA) e transporte de aminoácidos (proteína GpmA), entre outros.

Partial purification and characterization of antimicrobial peptide(s) from Mimosa pudica (Mimosaceae)

@#Plants have been a major source of natural products for sustaining human health. The use of the different parts of the plant as infusions, decoctions, extracts, and powders are being employed in the treatment of different diseases in humans, plants, and animals. One property of great significance in terms of therapeutic treatments, especially with the emergence of multi-drug resistant microbes, is the antimicrobial activity. A new promising source of antimicrobials that demonstrate novel mechanisms of therapeutic strategies is low molecular weight peptides. In this study, the antimicrobial activities of Mimosa pudica crude and partially purified peptide extracts against Gram-negative Enterobacter cloacae ATCC 23355 and Enterobacter aerogenes ATCC 13048, and Gram-positive Staphylococcus epidermidis ATCC 12228 using resazurin colorimetric assay and tricine SDS-PAGE bioautography were reported. M. pudica crude and partially purified extracts exhibited antimicrobial activity against all the bacteria tested. Specifically, the peptide that was partially purified from M. pudica with a molecular weight of 5.14 kDa inhibited the growth of Enterobacter cloacae.

Identification and recombinant expression of an antimicrobial peptide (cecropin B-like) from soybean pest Anticarsia gemmatalis

Insects can be found in numerous diverse environments, being exposed to pathogenic organisms like fungi and bacteria. Once these pathogens cross insect physical barriers, the innate immune system operates through cellular and humoral responses. Antimicrobial peptides are small molecules produced by immune signaling cascades that develop an important and generalist role in insect defenses against a variety of microorganisms. In the present work, a cecropin B-like peptide (AgCecropB) sequence was identified in the velvetbean caterpillar Anticarsia gemmatalis and cloned in a bacterial plasmid vector for further heterologous expression and antimicrobial tests. Methods AgCecropB sequence (without the signal peptide) was cloned in the plasmid vector pET-M30-MBP and expressed in the Escherichia coli BL21(DE3) expression host. Expression was induced with IPTG and a recombinant peptide was purified using two affinity chromatography steps with Histrap column. The purified peptide was submitted to high-resolution mass spectrometry (HRMS) and structural analyses. Antimicrobial tests were performed using gram-positive (Bacillus thuringiensis) and gram-negative (Burkholderia kururiensis and E. coli) bacteria. Results AgCecropB was expressed in E. coli BL21 (DE3) at 28°C with IPTG 0.5 mM. The recombinant peptide was purified and enriched after purification steps. HRMS confirmed AgCrecropB molecular mass (4.6 kDa) and circular dichroism assay showed α-helix structure in the presence of SDS. AgCrecropB inhibited almost 50% of gram-positive B. thuringiensis bacteria growth. Conclusions The first cecropin B-like peptide was described in A. gemmatalis and a recombinant peptide was expressed using a bacterial platform. Data confirmed tertiary structure as predicted for the cecropin peptide family. AgCecropB was capable to inhibit B. thuringiensis growth in vitro.(AU)

PEGuilação do peptídeo Lunatina-1 visando novo candidato à fármaco antimicrobiano / PEGylation of the peptide Lunatin-1 aiming at novel candidate for antimicrobial drug

As infecções relacionadas à assistência à saúde (IRAS) podem ser causadas por bactérias, vírus e fungos, sendo de extrema importância para o sistema de tratamento e pacientes. Com o alarmante avanço no surgimento de bactérias resistentes, tem havido uma preocupação crescente com as IRAS de origem bacteriana. Nesse sentido, várias pesquisas buscam alternativas para os fármacos antimicrobianos convencionais, sendo que os peptídeos antimicrobianos (AMPs), como a lunatina-1, aparecem como moléculas promissoras. No entanto, os AMPs geralmente apresentam rápida degradação proteolítica no trato gastrointestinal e meia-vida curta na corrente sanguínea, principais fatores limitantes para sua aplicação no tratamento de IRAS. Entre as estratégias empregadas para superar esses inconvenientes, a PEGuilação apresenta-se como alternativa eficaz que aumenta o tempo de circulação in vivo dos AMPs, resultando na melhora farmacocinética e, em alguns casos, também farmacodinâmica. A PEGuilação consiste na ligação covalente de cadeias de polietileno glicol (PEG) ao peptídeo, que pode ser efetuada por meio de uma reação aleatória ou sítio-específica. Neste trabalho, desenvolveu-se uma PEGuilação sítio-específica no N-terminal da lunatina-1 empregando-se mPEG-NHS de 2 kDa em tampão fosfato 100 mM, visando o aumento da solibilidade deste peptídeo, bem como para avaliar sua ação antimicrobiana. Com relação à reação de PEGuilação, avaliou-se a influência da razão molar PEG:peptídeo (10:1 ou 15:1) a pH 8,5. Foi obtido um rendimento de PEGuilação de 92%, através da análise por RP-HPLC quantitativo. Quanto à purificação da lunatina-1 PEGuilada, foi empregada a técnica semi-preparativa de RP-HPLC utilizando a coluna C18. A caracterização da lunatina-1 PEGuilada, incluindo determinação do grau de PEGuilação, foi realizada por MALDI-TOF Autoflex Speed (Bruker), mostrando que a molécula foi monoPEGuilada na região N-terminal. A atividade antimicrobiana de lunatina-1 livre e bioconjugada frente a diferentes cepas bacterianas, sendo duas Gram-negativas (ATCC 25922 de Escherichia coli e ATCC 9027 de Pseudomonas aeruginosa) e uma Gram-positiva (CECT 239 de Staphylococcus aureus), foi estudada por determinação da concentração inibitória mínima (CIM) em microplaca, sendo que foram obtidos valores de CIM de 86 e 140 µM para o peptídeo liver e PEGuilado, respetivamente. O potencial hemolítico também foi estudado, sendo que a forma PEGuilada mostrou significativa redução da atividade hemolítica em comparação à forma livre. Em suma, a PEGuilação da lunatina-1, aumenta a sua solubilidade e reduz a atividade hemolítica. Porém, para viabilizar esta estratégia a PEGuilação deve ser reversível, pois a conjugação ao polímero reduz atividade antimicrobiana

Health care-related infections (HAIs) caused by bacteria, viruses and fungi are extremely important for patients and health systems. With the alarming advance in the emergence of resistant bacteria, a growing concern with HAIs of bacterial origin is observed. In this sense, several studies investigate alternatives to conventional antimicrobial drugs and antimicrobial peptides (AMPs), such as lunatin-1, appear as promising molecules. However, AMPs generally show rapid proteolytic degradation in the gastrointestinal tract and short half-life in the bloodstream, the main limiting factors for their therapeutic application to treat HAIs. Among the strategies used to overcome these drawbacks, PEGylation presents itself as an effective alternative that increases the in vivo circulation time of AMPs, resulting in improved pharmacokinetics and, in some cases, also pharmacodynamics. PEGylation consists on the covalent attachment of polyethylene glycol (PEG) chains to the peptide, which can be carried out by means of a random or site-specific reaction. In this work, a site-specific PEGylation was developed at the N-terminus of lunatin-1 using 2 kDa mPEG-NHS to increase the solubility of this peptide, as well as to evaluate its antimicrobial activity. Regarding the PEGylation reaction, the influence of the molar ratio PEG: peptide (10: 1 or 15: 1) at pH 8.5 was evaluated and a PEGylation yield of 92% was obtained, based on quantitative RP-HPLC analysis. As for the purification of PEGylated lunatin-1, semi-preparative RP-HPLC was used. The characterization of PEGylated lunatin-1, including determination of the degree of PEGylation, was performed by MALDI-TOF Autoflex Speed (Bruker), showing that the peptide was monoPEGylated in the N-terminal region. The antimicrobial activity of free and bioconjugated lunatin-1 against different bacterial strains, two Gram-negative (ATCC 25922 from Escherichia coli and ATCC 9027 from Pseudomonas aeruginosa), and one Gram positive (CECT 239 from Staphylococcus aureus), was studied by determining the minimum inhibitory concentration (MIC) in a microplate, resulting in MIC values of 86 and 140 µM for the free and PEGylated peptide, respectively. The hemolytic potential was also studied and the PEGylated form showed a significant reduction in hemolytic activity compared to the free form. In short, the PEGylation of lunatin-1 increases its solubility and reduces hemolytic activity. However, to make this strategy feasible, PEGylation must be reversible, since the conjugation to the polymer reduces antimicrobial activity

Efficacy of a cooling gel containing calcium-based antimicrobial peptide compounds combined with desonide cream in the treatment of atopic dermatitis in children: a randomized, double-blind controlled clinical study / 中华皮肤科杂志

Objective:To evaluate short-term clinical efficacy and safety of a cooling gel containing calcium-based antimicrobial peptide compounds (CAPCS cooling gel) combined with desonide cream in the treatment of atopic dermatitis (AD) in children.Methods:From November 2019 to September 2020, a randomized, double-blind controlled clinical trial was conducted in 60 children with AD enrolled from Department of Dermatology and Venereology, West China Hospital, Sichuan University. The 60 patients were randomly and equally divided into 2 groups: test group treated with topical desonide cream in the morning and evening as well as topical CAPCS cooling gel at noon during the first 3 days of treatment, followed by topical CAPCS cooling gel in the morning, at midday and in the evening for 11 days; control group treated with topical desonide cream in the morning and evening as well as topical CAPCS-free placebo gel at noon during the first 3 days of treatment, followed by topical CAPCS-free placebo gel in the morning, at midday and in the evening for 11 days. The treatment lasted 2 weeks. Finally, 56 AD patients completed the follow-up, and 28 in each group were included into the following analysis. Clinical indices, such as eczema area and severity index (EASI) , visual analogue scale (VAS) , investigator′s global assessment (IGA) and dermatology life quality index (DLQI) , were recorded before, 7 ± 3 days and 14 ± 3 days after the treatment, so were adverse reactions.Results:After 1-week treatment, 1 patient in the test group and 1 in the control group showed response to the treatment, with the response rate being 3.57% in both groups; after 2-week treatment, 12 patients in the test group and 2 in the control group showed response to the treatment, with response rates being 42.86% and 7.14% respectively; there were significant differences in the treatment outcomes between the two groups after 1- and 2-week treatment ( Z = -4.318, -5.474, respectively, both P < 0.05) . There was no significant difference in the EASI, VAS, IGA or DLQI score between the two groups before treatment (all P > 0.05) ; nonparametric Friedman test showed a significant difference in the changing trend of the EASI score over time between the two groups ( χ2 = 45.720, P < 0.05) . Two-way repeated measurement analysis of variance showed a significant difference in the VAS score ( F = 10.738, P = 0.002) , but no significant difference in IGA or DLQI score between the test group and control group after 1-week treatment ( F = 0.066, 0.804, P = 0.135, 0.374, respectively) ; after 2-week treatment, there were significant differences in the VAS, IGA and DLQI score between the 2 groups ( F = 67.313, 38.949, 51.503, respectively, all P < 0.001) . During the clinical study period, 1 adverse event occurred in the test group and control group each, which manifested as tingling or irritating sensation at the topically treated sites, and there was no significant difference in the incidence rate of adverse events between the two groups ( P > 0.05) . Conclusion:Short-term topical application of CAPCS cooling gel combined with desonide cream is effective for the treatment of AD in children, and does not increase the incidence of adverse reactions compared with the placebo.

Partial characterization of bacteriocin-like compound (BLIS) produced by Burkholderia stagnalis strain K23/3 against Burkholderia pseudomallei

Aims@#Burkholderia pseudomallei, the human pathogen that causes melioidosis, is intrinsically resistant towards a wide range of antibiotics and there have been reports of acquired resistance towards antibiotics used for melioidosis treatments. Antimicrobial peptides (AMP) such as bacteriocins are gaining the interests of researchers as alternative for treating infections caused by multidrug resistant bacteria. In this study, we aimed to identify Burkholderia spp. isolated from soil in Sarawak that possess the potential in inhibiting the growth of B. pseudomallei and to further characterize the antagonistic compound produced.@*Methodology and results@#A total of 50 Burkholderia spp. isolates of environmental origin and two isolates of Ralstonia solanacearum were screened against five clinical isolates of B. pseudomallei using spot-on-lawn assay and flip streak method. Burkholderia stagnalis isolate K23/3 showed clear zones of inhibition (ZOI) in both preliminary tests. Cell-free supernatant (CFS) was obtained from B. stagnalis K23/3 broth culture and was tested via agar well diffusion assay (AWDA). The antagonistic compound secreted at the early log phase of the bacterial growth was shown to be stable in a wide range of temperatures and pH. Treatment with different enzymes revealed that it was sensitive towards proteinase K, suggesting that it is proteinaceous. The bacteriocin-like-substance (BLIS) was subjected to ammonium sulfate precipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The SDS-PAGE gel was overlaid with indicator B. pseudomallei isolates where the active protein was shown to be less than 7.1 kDa.@*Conclusion, significance and impact of study@#Burkholderia stagnalis isolate K23/3 was able to secrete bacteriocin-like-substance (BLIS) that has the potential in biocontrol of B. pseudomallei in the environment or as potential treatment for melioidosis.

Production of antimicrobial peptide (Oxysterlin 1) in Escherichia coli with ELP self-cleavage tag / 生物工程学报

Antimicrobial peptides are the most promising alternatives to antibiotics. However, the strategy of producing antimicrobial peptides by recombinant technology is complicated and expensive, which is not conducive to the large-scale production. Oxysterlin 1 is a novel type of cecropin antimicrobial peptide mainly targeting on Gram-negative bacteria and is of low cytotoxicity. In this study, a simple and cost-effective method was developed to produce Oxysterlin 1 in Escherichia coli. The Oxysterlin 1 gene was cloned into a plasmid containing elastin-like polypeptide (ELP) and protein splicing elements (intein) to construct the recombinant expression plasmid (pET-ELP-I-Oxysterlin 1). The recombinant protein was mainly expressed in soluble form in E. coli, and then the target peptide can be purified with a simple salting out method followed by pH changing. The final yield of Oxysterlin 1 was about 1.2 mg/L, and the subsequent antimicrobial experiment showed the expected antimicrobial activity. This study holds promise for large-scale production of antimicrobial peptides and the in-depth study of its antimicrobial mechanism.

Application of supramolecular peptide self-assembly in biomedicine / 生物工程学报

In recent years, peptide self-assembly has received much attention because of its ability to form regular and ordered structures with diverse functions. Self-assembled peptides can form aggregates with defined structures under specific conditions. They show different characteristics and advantages (e.g., good biocompatibility and high stability) compared with monomeric peptides, which form the basis for potential application in the fields of drug delivery, tissue engineering, and antiseptics. In this paper, the molecular mechanisms, types and influencing factors of forming self-assembled peptides were reviewed, followed by introducing the latest advances on fibrous peptide hydrogels and self-assembled antimicrobial peptides. Furthermore, the challenges and perspectives for peptide self-assembly technology were discussed.

The effects of hinge structure on the biological activity of antimicrobial peptides and its application in molecular design: a review / 生物工程学报

The hinge structure, also known as hinge region or bend, is a special structure found in some antimicrobial peptides. Most studies on antimicrobial peptides focused on the standard secondary structure of α-helix and β-sheet, while the hinge structure and its functions were rarely studied. The hinge structure confers the antimicrobial peptides an improved structural flexibility, which may promote their disruptive effect on bacterial membrane or their binding efficiency to the intracellular targets, thus resulting in a higher antibacterial activity. Meanwhile, the hinge structure may reduce the structural rigidity, which may eliminate the cytotoxicity of antimicrobial peptides to eukaryotic cells. This article reviews the structural characteristics of the hinge structure, its effects on the biological activity of antimicrobial peptides and application in the molecular design, with the aim to provide a reference for the design and development of new antimicrobial peptides.

The level of antimicrobial peptides in gingival crevicular fluid and its correlation with periodontal clinical indexes in elderly patients with type 2 diabetic periodontitis / 口腔疾病防治

Objective@#To investigate the changes and significance of human beta-defensin-2 (HBD-2) and LL-37 in the gingival crevicular fluid of patients with periodontitis and type 2 diabetes mellitus (T2DM).@*Methods@#This study was conducted among 45- to 85-year-old patients in the Department of Stomatology and Internal Medicine of Shenzhen Center for Chronic Disease Control, including a healthy control group of 22 people, a systemically healthy control group of 19 people with periodontitis, a T2DM periodontal health group of 15 people, and a T2DM group of 21 people with periodontitis. The Florida periodontal probe was used for periodontal examination, and the clinical indexes, including probing depth (PD), clinical attachment level (CAL) and probing on bleeding (BOP), were recorded. The concentrations of HBD-2 and Ll-37 in gingival crevicular fluid were determined by ELISA. The differences in HBD-2, LL-37 and periodontal clinical indexes between the groups were compared, and correlation analysis was conducted.@*Results@#The PD values in T2DM with the periodontitis group were higher than those of the systemically healthy controls with periodontitis group (P < 0.05); the levels of HBD-2 and LL-37 in gingival crevicular fluid in systemically healthy controls with periodontitis group were significantly higher than those in the healthy control group (P < 0.05), the level of HBD-2 in gingival crevicular fluid in systemically healthy controls with periodontitis group was significantly higher than that in T2DM with periodontitis group (P < 0.05); and the antimicrobial peptides HBD-2 and LL-37 in gingival crevicular fluid were significantly positively correlated with the PD and CAL in systemically healthy controls with periodontitis group (P < 0.05), and there was no significant correlation between the antimicrobial peptides HBD-2, LL-37 in gingival crevicular fluid and PD, CAL in T2DM with periodontitis group (P > 0.05).@*Conclusion@#The levels of antimicrobial peptides HBD-2 and LL-37 in gingival crevicular fluid of middle-aged and elderly patients with T2DM periodontitis were lower, and there was no significant correlation with PD and CAL in periodontal clinical indicators.