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American Journal of Physiology.... Sep 2021Neonatal antibiotics administered to human infants initiate gut microbiota dysbiosis that may have long-term effects on body weight and metabolism. We examined...
Neonatal antibiotics administered to human infants initiate gut microbiota dysbiosis that may have long-term effects on body weight and metabolism. We examined antibiotic-induced adaptations in pancreatic islets of the piglet, a well-accepted model of human infant microbiota and pancreas development. Neonatal piglets randomized to amoxicillin [30 mg/kg body wt/day; = 7, antibiotic (ANTI)] or placebo [vehicle control; = 7, control (CON)] from ()- were euthanized at , , and . The metabolic phenotype along with functional, immunohistological, and transcriptional phenotypes of the pancreatic islets were studied. The gut microbiome was characterized by 16S rRNA gene sequencing, and microbial metabolites and microbiome-sensitive host molecules were measured. Compared with CON, ANTI piglets had elevated transcripts of genes involved in glucagon-like peptide 1 ((GLP-1) synthesis or signaling in islets ( < 0.05) coinciding with higher plasma GLP-1 ( = 0.11), along with increased tumor necrosis factor α () ( < 0.05) and protegrin 1 () ( < 0.05). Antibiotic-induced relative increases in , , , , and of the ileal microbiome at normalized after antibiotic withdrawal. In ANTI islets at , the expression of key regulators pancreatic and duodenal homeobox 1 (), insulin-like growth factor-2 (), and transcription factor 7-like 2 () was downregulated, preceding a 40% reduction of β-cell area ( < 0.01) and islet insulin content at ( < 0.05). At , a twofold elevated plasma insulin concentration ( = 0.07) was observed in ANTI compared with CON. We conclude that antibiotic treatment of neonatal piglets elicited gut microbial changes accompanied by phasic alterations in key regulatory genes in pancreatic islets at and . By , reduced β-cell area and islet insulin content were accompanied by elevated nonfasted insulin despite normoglycemia, indicative of islet stress.
Topics: Animals; Anti-Bacterial Agents; Gastrointestinal Microbiome; Glucagon; Glucagon-Like Peptide 1; Insulin; Insulin-Secreting Cells; Islets of Langerhans; Swine
PubMed: 34259034
DOI: 10.1152/ajpregu.00090.2021 -
Genetics and Molecular Research : GMR Oct 2008Some antimicrobial peptides have a broad spectrum of action against many different kinds of microorganisms. Gomesin and protegrin-1 are examples of such antimicrobial...
Some antimicrobial peptides have a broad spectrum of action against many different kinds of microorganisms. Gomesin and protegrin-1 are examples of such antimicrobial peptides, and they were studied by molecular dynamics in this research. Both have a beta-hairpin conformation stabilized by two disulfide bridges and are active against gram-positive and gram-negative bacteria, as well as fungi. In this study, the role of the disulfide bridge in the maintenance of the tertiary peptide structure of protegrin-1 and gomesin is analyzed by the structural characteristics of these peptides and two of their respective variants, gomy4 and proty4, in which the four cysteines are replaced by four tyrosine residues. The absence of disulfide bridges in gomy4 and proty4 is compensated by overall reinforcement of the original hydrogen bonds and extra attractive interactions between the aromatic rings of the tyrosine residues. The net effects on the variants with respect to the corresponding natural peptides are: i) maintenance of the original beta-hairpin conformation, with great structural similarities between the mutant and the corresponding natural peptide; ii) combination of positive Phi and Psi Ramachandran angles within the hairpin head region with a qualitative change to a combination of positive (Phi) and negative (Psi) angles, and iii) significant increase in structural flexibility. Experimental facts about the antimicrobial activity of the gomesin and protegrin-1 variants have also been established here, in the hope that the detailed data provided in the present study may be useful for understanding the mechanism of action of these peptides.
Topics: Anti-Infective Agents; Antimicrobial Cationic Peptides; Databases, Protein; Disulfides; Hydrogen Bonding; Models, Molecular; Molecular Conformation; Protein Structure, Secondary; Structure-Activity Relationship
PubMed: 19048486
DOI: 10.4238/vol7-4gmr507 -
Frontiers in Nutrition 2021The aim of this study was to evaluate the effect of larvae meal (HI) on the growth performance and intestinal barrier function of weaned pigs. To achieve this, 72...
The aim of this study was to evaluate the effect of larvae meal (HI) on the growth performance and intestinal barrier function of weaned pigs. To achieve this, 72 weaned pigs [28-day-old, 8.44 ± 0.04 kg body weight (BW)] were randomly assigned to three dietary treatments: basal diet (negative control, NC), zinc oxide-supplemented diet (positive control, PC), and HI-supplemented diet [100% replacement of fishmeal (FM), HI], for 28 days in the presence of enterotoxigenic (ETEC). The results showed that HI and PC increased ( < 0.05) the average daily gain (ADG) and average daily feed intake (ADFI) of weaned pigs from day 1 to 14, and decreased diarrhea incidence from day 1 to 28. Additionally, HI increased ( < 0.05) claudin-1, occludin, mucin-1 (), and MUC-2 expression, goblet cell number, and secretory immunoglobulin A (sIgA) concentration in the intestine of weaned pigs. Compared with NC, HI downregulated ( < 0.05) interleukin-1β (β) and expression, and upregulated , transforming growth factor-β (β), antimicrobial peptide [porcine β defensin 1 (), , protegrin 1-5 ()] expression in the jejunum or ileum. Moreover, HI decreased ( < 0.05) toll-like receptor 2 (TLR2), phosphorylated nuclear factor-κB (p-NF-κB), and phosphorylated mitogen-activated protein kinase (p-MAPK) expression, and increased sirtuin 1 (SIRT1) expression in the ileum. Additionally, HI increased histone deacetylase 3 (HDAC3) expression and acetylation of histone 3 lysine 27 (acH3k27) in the ileum. Furthermore, HI positively influenced the intestinal microbiota composition and diversity of weaned pigs and increased ( < 0.05) butyrate and valerate concentrations. Overall, dietary HI improved growth performance and intestinal barrier function, as well as regulated histone acetylation and TLR2-NF-κB/MAPK signaling pathways in weaned pigs.
PubMed: 35118109
DOI: 10.3389/fnut.2021.812011 -
Molecules (Basel, Switzerland) Jan 2022Brain cancer treatment, where glioblastoma represents up to 50% of all CNS malignancies, is one of the most challenging calls for neurooncologists. The major driver of...
Brain cancer treatment, where glioblastoma represents up to 50% of all CNS malignancies, is one of the most challenging calls for neurooncologists. The major driver of this study was a search for new approaches for the treatment of glioblastoma. We tested live , cathelicidin family peptides and NGF, assessing the oncolytic activity of these compounds as monotherapy or in combination with chemotherapeutics. For cytotoxicity evaluation, we used the MTT assay, trypan blue assay and the xCELLigence system. To evaluate the safety of the studied therapeutic approaches, we performed experiments on normal human fibroblasts. Streptococci and peptides demonstrated high antitumor efficiency against glioma C6 cells in all assays applied, surpassing the effect of chemotherapeutics (doxorubicin, carboplatin, cisplatin, etoposide). A real-time cytotoxicity analysis showed that the cell viability index dropped to 21% 2-5 h after strain exposure. It was shown that LL-37, PG-1 and NGF also exhibited strong antitumor effects on C6 glioma cells when applied at less than 10 M. Synergistic effects for combinations of PG-1 with carboplatin and LL-37 with etoposide were shown. Combinations of strain #7 with NGF or LL-37 demonstrated a cytotoxic effect (56.7% and 57.3%, accordingly) on C6 glioma cells after 3 h of exposure.
Topics: Antimicrobial Cationic Peptides; Cathelicidins
PubMed: 35056889
DOI: 10.3390/molecules27020569 -
Microorganisms Sep 2023Antimicrobial peptides (AMPs) can directly kill Gram-positive bacteria, Gram-negative bacteria, mycobacteria, fungi, enveloped viruses, and parasites. At sublethal...
Antimicrobial peptides (AMPs) can directly kill Gram-positive bacteria, Gram-negative bacteria, mycobacteria, fungi, enveloped viruses, and parasites. At sublethal concentrations, some AMPs and also conventional antibiotics can stimulate bacterial response increasing their resilience, also called the hormetic response. This includes stimulation of growth, mobility, and biofilm production. Here, we describe the discovery of AMPs that stimulate the growth of certain mycobacteria. Peptide 14 showed a growth stimulating effect on (MTB), , subsp. (MAP), , and The effect was more pronounced at low bacterial inocula. The peptides induce a faster transition from the lag phase to the log phase and keep the bacteria longer in the log phase before entering stationary phase when compared to nontreated controls. In some cases, an increase in the division rate was observed. An initial screen using MAP and a collection of 75 peptides revealed 13 peptides with a hormetic effect. For MTB, a collection of 25 artificial peptides were screened and 13 were found to reduce the time to positivity (TTP) by at least 5%, improving growth. A screen of 43 naturally occurring peptides, 11 fragments of naturally occurring peptides and 5 designed peptides, all taken from the database APD3, identified a further 44 peptides that also lowered TTP by at least 5%. Lasioglossin LL-III (Bee) and Ranacyclin E (Frog) were the most active natural peptides, and the human cathelicidin LL37 fragment GF-17 and a porcine cathelicidin protegrin-1 fragment were the most active fragments of naturally occurring peptides. Peptide 14 showed growth-stimulating activity between 10 ng/mL and 10 µg/mL, whereas the stability-optimised Peptide 14D had a narrow activity range of 0.1-1 µg/mL. Peptides identified in this study are currently in commercial use to improve recovery and culture for the diagnostics of mycobacteria in humans and animals.
PubMed: 37764069
DOI: 10.3390/microorganisms11092225 -
Peptides Jan 2010Antimicrobial peptides (AMPs), important effector molecules of the innate immune system, also provide templates for designing novel antibiotics. Protegrin, an especially...
Antimicrobial peptides (AMPs), important effector molecules of the innate immune system, also provide templates for designing novel antibiotics. Protegrin, an especially potent AMP found in porcine leukocytes, was recently shown to form octameric transmembrane pores. We have employed a combination of experiments and models spanning length scales from the atomistic to the cellular level in order to elucidate the microbicidal mechanism of protegrin. Comparison of the modeling and experimental data suggests that approximately 10-100 protegrin pores are necessary to explain the observed rates of potassium leakage and Escherichia coli death in exponential-phase bacteria. The kinetics of viability loss suggest that bacterial death results largely from uncontrolled ion exchange processes and decay of transmembrane potential. However, ion exchange processes alone cannot account for the experimentally observed cell swelling and osmotic lysis-a redundant "overkill" mechanism most likely to occur in locales with high protegrin concentrations. Although our study is limited to protegrin and E. coli, the timeline of events described herein is likely shared by other AMPs that act primarily by permeabilizing microbial membranes. This work provides many of the missing links in describing antimicrobial action, as well as providing a quantitative connection between several previous experimental and simulation studies of protegrin.
Topics: Anti-Infective Agents; Antimicrobial Cationic Peptides; Escherichia coli; Ions; Membrane Potentials; Models, Theoretical; Molecular Dynamics Simulation; Protein Conformation
PubMed: 19931583
DOI: 10.1016/j.peptides.2009.11.010 -
The Journal of Physical Chemistry. B Dec 2011Molecular dynamics (MD) simulations are used to study the pathway for the insertion of the cationic antimicrobial peptide protegrin-1 (PG1) into mixed anionic lipid...
Molecular dynamics (MD) simulations are used to study the pathway for the insertion of the cationic antimicrobial peptide protegrin-1 (PG1) into mixed anionic lipid bilayers composed of palmitoyl-oleoyl-phosphatidylglycerol (POPG) and palmitoyl-oleoyl-phosphatidylethanolamine (POPE) in a 1:3 ratio (POPG/POPE). We calculate the potential of mean force (PMF) during the transfer of the peptide from the bulk aqueous phase to the transmembrane (TM) configuration using the adaptive biasing force (ABF) method. We find that the PMF has two energy minima separated by an energy barrier. One minimum corresponds to the fully transmembrane inserted state, with a free energy of -20.1 kcal/mol. The second PMF minimum, which corresponds to adsorption to the membrane surface, has a value of -2.5 kcal/mol. The PMF also shows the existence of a free energy barrier of +6.3 kcal/mol for the insertion process. Using the Kramers theory Langevin equation and the Grote-Hynes theory generalized Langevin equation, we calculated the transmission coefficient for PG1 diffusion through the potential barrier. We focus on the use of the PMF and the time correlation function of the fluctuation of the instantaneous force to calculate the rate constants for insertion/deinsertion of PG1 from the mixed POPG/POPE membrane. The influence of the activation free energy barrier on the dynamics of the insertion and permeation of peptides through the membrane are discussed.
Topics: Antimicrobial Cationic Peptides; Lipid Bilayers; Molecular Dynamics Simulation; Permeability; Phosphatidylethanolamines; Phosphatidylglycerols; Thermodynamics
PubMed: 22044268
DOI: 10.1021/jp205153y -
ACS Infectious Diseases Jun 2016Bacteria have acquired extensive resistance mechanisms to protect themselves against antibiotic action. Today the bacterial membrane has become one of the "final...
Bacteria have acquired extensive resistance mechanisms to protect themselves against antibiotic action. Today the bacterial membrane has become one of the "final frontiers" in the search for new compounds acting on novel targets to address the threat of multi-drug resistant (MDR) and XDR bacterial pathogens. β-Hairpin antimicrobial peptides are amphipathic, membrane-binding antibiotics that exhibit a broad range of activities against Gram-positive, Gram-negative, and fungal pathogens. However, most members of the class also possess adverse cytotoxicity and hemolytic activity that preclude their development as candidate antimicrobials. We examined peptide hydrophobicity, amphipathicity, and structure to better dissect and understand the correlation between antimicrobial activity and toxicity, membrane binding, and membrane permeability. The hydrophobicity, p, net charge at physiological pH, and amphipathic moment for the β-hairpin antimicrobial peptides tachyplesin-1, polyphemusin-1, protegrin-1, gomesin, arenicin-3, and thanatin were determined and correlated with key antimicrobial activity and toxicity data. These included antimicrobial activity against five key bacterial pathogens and two fungi, cytotoxicity against human cell lines, and hemolytic activity in human erythrocytes. Observed antimicrobial activity trends correlated with compound amphipathicity and, to a lesser extent, with overall hydrophobicity. Antimicrobial activity increased with amphipathicity, but unfortunately so did toxicity. Of note, tachyplesin-1 was found to be 8-fold more amphipathic than gomesin. These analyses identify tachyplesin-1 as a promising scaffold for rational design and synthetic optimization toward an antibiotic candidate.
PubMed: 27331141
DOI: 10.1021/acsinfecdis.6b00045 -
Acta Naturae 2023Bacterial infections caused by antibiotic-resistant pathogens pose an extremely serious and elusive problem in healthcare. The discovery and targeted creation of new...
Bacterial infections caused by antibiotic-resistant pathogens pose an extremely serious and elusive problem in healthcare. The discovery and targeted creation of new antibiotics are today among the most important public health issues. Antibiotics based on antimicrobial peptides (AMPs) are of particular interest due to their genetically encoded nature. A distinct advantage of most AMPs is their direct mechanism of action that is mediated by their membranolytic properties. The low rate of emergence of antibiotic resistance associated with the killing mechanism of action of AMPs attracts heightened attention to this field. Recombinant technologies enable the creation of genetically programmable AMP producers for large-scale generation of recombinant AMPs (rAMPs) or the creation of rAMP-producing biocontrol agents. The methylotrophic yeast Pichia pastoris was genetically modified for the secreted production of rAMP. Constitutive expression of the sequence encoding the mature AMP protegrin-1 provided the yeast strain that effectively inhibits the growth of target gram-positive and gram-negative bacteria. An antimicrobial effect was also observed in the microculture when a yeast rAMP producer and a reporter bacterium were co-encapsulated in droplets of microfluidic double emulsion. The heterologous production of rAMPs opens up new avenues for creating effective biocontrol agents and screening antimicrobial activity using ultrahigh-throughput technologies.
PubMed: 37153506
DOI: 10.32607/actanaturae.11878 -
Antibiotics (Basel, Switzerland) Dec 2014Protegrins are porcine antimicrobial peptides (AMPs) that belong to the cathelicidin family of host defense peptides. Protegrin-1 (PG-1), the most investigated member of...
Protegrins are porcine antimicrobial peptides (AMPs) that belong to the cathelicidin family of host defense peptides. Protegrin-1 (PG-1), the most investigated member of the protegrin family, is an arginine-rich peptide consisting of 18 amino acid residues, its main chain adopting a β-hairpin structure that is linked by two disulfide bridges. We report on the immune modulatory activity of PG-1 and its analogs in neutralizing bacterial endotoxin and capsular polysaccharides, consequently inhibiting inflammatory mediators' release from macrophages. We demonstrate that the β-hairpin structure motif stabilized with at least one disulfide bridge is a prerequisite for the immune modulatory activity of this type of AMP.
PubMed: 26097747
DOI: 10.3390/antibiotics3040694