The increase in resistant bacterial strains necessitates the identification of new antimicrobial molecules. Antimicrobial peptides (AMPs) are an attractive option because of evidence that bacteria cannot easily develop resistance to AMPs. The peptaibols, a class of naturally occurring AMPs, have shown particular promise as antimicrobial drugs, but their development has been hindered by their mechanism of action not being clearly understood. To explore how peptaibols might interact with membranes, circular dichroism, vibrational circular dichroism, linear dichroism, Raman spectroscopy, Raman optical activity, neutron reflectivity and molecular dynamics simulations have been used to study a small library of peptaibol mimics, the Aib-rich peptides. All the peptides studied quickly partitioned and oriented in membranes, and we found evidence of chiral interactions between the phospholipids and membrane-embedded peptides. The protocols presented in this paper open new ground by showing how chiro-optical spectroscopies can throw light on the mechanism of action of AMPs.

• MeSH
• cirkulární dichroismus MeSH
• fosfatidylcholiny chemie   MeSH
• kationické antimikrobiální peptidy chemie   metabolismus   MeSH
• lipidové dvojvrstvy chemie   metabolismus   MeSH
• peptaiboly chemie   metabolismus   MeSH
• simulace molekulární dynamiky * MeSH
• stereoizomerie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Respiratory infections are a real threat for humans, and therefore the pig model is of interest for studies. As one of a case for studies, Actinobacillus pleuropneumoniae (APP) caused infections and still worries many pig breeders around the world. To better understand the influence of pathogenic effect of APP on a respiratory system-lungs and tracheobronchial lymph nodes (TBLN), we aimed to employ matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-TOF MSI). In this study, six pigs were intranasally infected by APP and two were used as non-infected control, and 48 cryosections have been obtained. MALDI-TOF MSI and immunohistochemistry (IHC) were used to study spatial distribution of infectious markers, especially interleukins, in cryosections of porcine tissues of lungs (necrotic area, marginal zone) and tracheobronchial lymph nodes (TBLN) from pigs infected by APP. CD163, interleukin 1β (IL‑1β) and a protegrin-4 precursor were successfully detected based on their tryptic fragments. CD163 and IL‑1β were confirmed also by IHC. The protegrin-4 precursor was identified by MALDI-TOF/TOF directly on the tissue cryosections. CD163, IL‑1β and protegrin‑4 precursor were all significantly (p < 0.001) more expressed in necrotic areas of lungs infected by APP than in marginal zone, TBLN and in control lungs.

• MeSH
• Actinobacillus pleuropneumoniae patogenita   MeSH
• antigeny diferenciační myelomonocytární metabolismus   MeSH
• biologické markery metabolismus   MeSH
• bronchy metabolismus   MeSH
• CD antigeny metabolismus   MeSH
• infekce bakteriemi rodu Actinobacillus metabolismus   mikrobiologie   MeSH
• infekce dýchací soustavy metabolismus   mikrobiologie   MeSH
• interleukin-1beta metabolismus   MeSH
• kationické antimikrobiální peptidy metabolismus   MeSH
• lymfatické uzliny metabolismus   MeSH
• plíce metabolismus   MeSH
• prasata MeSH
• receptory buněčného povrchu metabolismus   MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice metody   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Every cell is protected by a semipermeable membrane. Peptides with the right properties, for example Antimicrobial peptides (AMPs), can disrupt this protective barrier by formation of leaky pores. Unfortunately, matching peptide properties with their ability to selectively form pores in bacterial membranes remains elusive. In particular, the proline/glycine kink in helical peptides was reported to both increase and decrease antimicrobial activity. We used computer simulations and fluorescence experiments to show that a kink in helices affects the formation of membrane pores by stabilizing toroidal pores but disrupting barrel-stave pores. The position of the proline/glycine kink in the sequence further controls the specific structure of toroidal pore. Moreover, we demonstrate that two helical peptides can form a kink-like connection with similar behavior as one long helical peptide with a kink. The provided molecular-level insight can be utilized for design and modification of pore-forming antibacterial peptides or toxins.

• MeSH
• biologické modely MeSH
• buněčná membrána chemie   metabolismus   MeSH
• hydrofobní a hydrofilní interakce MeSH
• kationické antimikrobiální peptidy chemie   metabolismus   MeSH
• konformace proteinů * MeSH
• metoda Monte Carlo MeSH
• molekulární modely MeSH
• poriny chemie   metabolismus   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Eggshell colour, quality, and biosafety of table eggs are of significant commercial interest. To date, there have been few studies investigating the relationship between eggshell pigmentation and internal egg quality in commercially bred birds. Moreover, the genetic basis and mechanisms behind the effects of extrinsic factors on deposition of antimicrobial compounds in egg white and eggshell pigments are not fully understood. In the present study, we evaluate the effect of chicken breed identity, eggshell pigmentation and the role of extrinsic factors (year and breeder identity) on variability in the concentrations of 2 major egg white antimicrobial proteins (AMPs), lysozyme (LSM), and ovotransferrin (OVOTR), across 23 traditional chicken breeds. We found that chicken breed identity and eggshell pigmentation explained most variability in the concentration of egg white LSM and OVOTR. Year and breeder identity were also significant predictors of egg white LSM and OVOTR variability, and showed selective effects on the deposition of both AMPs in egg white. We also documented a positive correlation between concentration of egg white LSM and eggshell cuticle protoporphyrin in tinted and dark brown eggs, but not in brown, white, and blue eggs. We assume that a combination of both intrinsic genetic and hormonally regulated extrinsic factors is responsible for this relationship and for the variability in egg white AMPs. In this study, we demonstrate the existence of a relationship between eggshell pigmentation and egg white AMPs content in the eggs of traditional chicken breeds that may advertise the egg's antimicrobial potential and biosafety. These findings provide novel insights into the relationship between eggshell pigmentation and egg internal quality and may stimulate the recovery and exploitation of traditional chicken breeds for egg production, where the demands for egg quality and biosafety, in conjunction with animal welfare, are a priority.

• MeSH
• imunomodulace genetika   MeSH
• kationické antimikrobiální peptidy genetika   metabolismus   MeSH
• kur domácí genetika   imunologie   metabolismus   MeSH
• pigmentace MeSH
• ptačí proteiny genetika   metabolismus   MeSH
• vaječná skořápka chemie   MeSH
• vaječné proteiny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

We addressed the onset of synergistic activity of the two well-studied antimicrobial peptides magainin 2 (MG2a) and PGLa using lipid-only mimics of Gram-negative cytoplasmic membranes. Specifically, we coupled a joint analysis of small-angle x-ray and neutron scattering experiments on fully hydrated lipid vesicles in the presence of MG2a and L18W-PGLa to all-atom and coarse-grained molecular dynamics simulations. In agreement with previous studies, both peptides, as well as their equimolar mixture, were found to remain upon adsorption in a surface-aligned topology and to induce significant membrane perturbation, as evidenced by membrane thinning and hydrocarbon order parameter changes in the vicinity of the inserted peptide. These effects were particularly pronounced for the so-called synergistic mixture of 1:1 (mol/mol) L18W-PGLa/MG2a and cannot be accounted for by a linear combination of the membrane perturbations of two peptides individually. Our data are consistent with the formation of parallel heterodimers at concentrations below a synergistic increase of dye leakage from vesicles. Our simulations further show that the heterodimers interact via salt bridges and hydrophobic forces, which apparently makes them more stable than putatively formed antiparallel L18W-PGLa and MG2a homodimers. Moreover, dimerization of L18W-PGLa and MG2a leads to a relocation of the peptides within the lipid headgroup region as compared to the individual peptides. The early onset of dimerization of L18W-PGLa and MG2a at low peptide concentrations consequently appears to be key to their synergistic dye-releasing activity from lipid vesicles at high concentrations.

• MeSH
• buněčná membrána metabolismus   MeSH
• dimerizace MeSH
• fosfatidylethanolaminy MeSH
• fosfatidylglyceroly MeSH
• kationické antimikrobiální peptidy metabolismus   MeSH
• lipidové dvojvrstvy chemie   MeSH
• lipidy chemie   MeSH
• magaininy metabolismus   MeSH
• simulace molekulární dynamiky MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We have investigated structural changes of peptides related to antimicrobial peptide Halictine-1 (HAL-1) induced by interaction with various membrane-mimicking models with the aim to identify a mechanism of the peptide mode of action and to find a correlation between changes of primary/secondary structure and biological activity. Modifications in the HAL-1 amino acid sequence at particular positions, causing an increase of amphipathicity (Arg/Lys exchange), restricted mobility (insertion of Pro) and consequent changes in antimicrobial and hemolytic activity, led to different behavior towards model membranes. Secondary structure changes induced by peptide-membrane interaction were studied by circular dichroism, infrared spectroscopy, and fluorescence spectroscopy. The experimental results were complemented by molecular dynamics calculations. An α-helical structure has been found to be necessary but not completely sufficient for the HAL-1 peptides antimicrobial action. The role of alternative conformations (such as β-sheet, PPII or 310-helix) also seems to be important. A mechanism of the peptide mode of action probably involves formation of peptide assemblies (possibly membrane pores), which disrupt bacterial membrane and, consequently, allow membrane penetration.

• MeSH
• antibakteriální látky chemie   metabolismus   MeSH
• fosfatidylcholiny chemie   MeSH
• fosfatidylglyceroly chemie   MeSH
• hydrofobní a hydrofilní interakce MeSH
• kationické antimikrobiální peptidy chemie   metabolismus   MeSH
• kinetika MeSH
• konformace proteinů, alfa-helix MeSH
• konformace proteinů, beta-řetězec MeSH
• lipidové dvojvrstvy chemie   MeSH
• permeabilita MeSH
• sekvence aminokyselin MeSH
• simulace molekulární dynamiky MeSH
• Publikační typ
• časopisecké články MeSH

The biochemical and molecular mechanisms underlying insect cold acclimation prior to cold stress are relatively well explored, but the mechanisms linked to recovery and repair after cold stress have received much less attention. Here we focus on recovery from cold stress in the larvae of the vinegar fly (Drosophila melanogaster) that were exposed to two physiologically distinct cold stress situations: supercooling (S, survival > 95%) and freezing (F, survival < 10%), both at -5 °C. We analysed the metabolic and transcriptomic responses to cold stress via GC-MS/LC-MS and whole-genome microarrays, respectively. Both stresses (S and F) caused metabolic perturbations which were transient in supercooled larvae but deeper and irreversible in frozen larvae. Differential gene expression analysis revealed a clear disparity in responses to supercooling and freezing (less than 10% of DE genes overlapped between S and F larvae). Using GO term enrichment analysis and KEGG pathway mapping, we identified the stimulation of immune response pathways as a strong candidate mechanism for coping with supercooling. Supercooling caused complex transcriptional activation of innate immunity potential: from Lysozyme-mediated degradation of bacterial cell walls, recognition of pathogen signals, through phagocytosis and lysosomal degradation, Toll and Imd signaling, to upregulation of genes coding for different antimicrobial peptides. The transcriptomic response to freezing was instead dominated by degradation of macromolecules and death-related processes such as autophagy and apoptosis. Of the 45 upregulated DE genes overlapping in responses to supercooling and freezing, 26 were broadly ascribable to defense and repair functions.

• MeSH
• Drosophila melanogaster imunologie   metabolismus   MeSH
• fyziologický stres imunologie   MeSH
• kationické antimikrobiální peptidy metabolismus   MeSH
• larva imunologie   metabolismus   MeSH
• nízká teplota MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We investigated the effect of Kluyveromyces lactis ERG6 gene deletion on plasma membrane function and showed increased susceptibility of mutant cells to salt stress, cationic drugs and weak organic acids. Contrary to Saccharomyces cerevisiae, Klerg6 mutant cells exhibited increased tolerance to tunicamycin. The content of cell wall polysacharides did not significantly vary between wild-type and mutant cells. Although the expression of the NAD+-dependent glycerol 3-phosphate dehydrogenase (KlGPD1) in the Klerg6 mutant cells was only half of that in the parental strain, it was induced in the presence of calcofluor white. Also, cells exposed to this drug accumulated glycerol. The absence of KlErg6p led to plasma membrane hyperpolarization but had no statistically significant influence on the plasma membrane fluidity. We propose that the phenotype of Klerg6 mutant cells to a large extent was a result of the reduced activity of specific plasma membrane proteins that require proper lipid composition for full activity.

• MeSH
• delece genu MeSH
• fungální proteiny genetika   metabolismus   MeSH
• fyziologická adaptace * MeSH
• kationické antimikrobiální peptidy metabolismus   MeSH
• Kluyveromyces účinky léků   enzymologie   genetika   fyziologie   MeSH
• kyseliny karboxylové toxicita   MeSH
• methyltransferasy genetika   metabolismus   MeSH
• osmotický tlak MeSH
• regulace genové exprese u hub * MeSH
• tolerance léku MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The microbial etiology and source of sepsis influence the inflammatory response. Therefore, the plasma levels of cytokines (IL-6, IL-8, and IL-10), chemokines (CCL2/MCP-1, MIP-1β), heparin-binding protein (HBP), soluble CD14 (sCD14), and cortisol were analyzed in blood from septic patients obtained during the first 96 hours of intensive care unit hospitalization. The etiology was established in 56 out of a total of 62 patients enrolled in the study. Plasma concentrations of MCP-1, sCD14, IL-6, and IL-10 were significantly higher in patients with community-acquired pneumonia (CAP; n = 10) and infective endocarditis (IE; n = 11) compared to those with bacterial meningitis (BM; n = 18). Next, cortisol levels were higher in IE patients than in those with BM and CAP, and at one time point, cortisol was also higher in patients with gram-negative sepsis when compared to those with gram-positive infections. Furthermore, cortisol and MCP-1 levels correlated positively with the daily measured SOFA score. In addition, HBP levels were significantly higher in patients with IE than in those with BM. Our findings suggest that MCP-1, sCD14, IL-6, IL-10, cortisol, and HBP are modulated by the source of sepsis and that elevated MCP-1 and cortisol plasma levels are associated with sepsis-induced organ dysfunction.

• MeSH
• antigeny CD14 metabolismus   MeSH
• biologické markery metabolismus   MeSH
• chemokin CCL2 metabolismus   MeSH
• chemokin CCL4 metabolismus   MeSH
• hydrokortison metabolismus   MeSH
• interleukin-10 metabolismus   MeSH
• interleukin-6 metabolismus   MeSH
• interleukin-8 metabolismus   MeSH
• kationické antimikrobiální peptidy metabolismus   MeSH
• krevní proteiny metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• péče o pacienty v kritickém stavu MeSH
• senioři MeSH
• sepse metabolismus   MeSH
• transportní proteiny metabolismus   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

LL-37, the only human cathelicidin that is released during inflammation, is a potent regulator of immune responses by facilitating delivery of oligonucleotides to intracellular TLR-9, thereby enhancing the response of human plasmacytoid dendritic cells (pDCs) to extracellular DNA. Although important for pathogen recognition, this mechanism may facilitate development of autoimmune diseases. In this article, we show that citrullination of LL-37 by peptidyl-arginine deiminases (PADs) hindered peptide-dependent DNA uptake and sensing by pDCs. In contrast, carbamylation of the peptide (homocitrullination of Lys residues) had no effect. The efficiency of LL-37 binding to oligonucleotides and activation of pDCs was found to be inversely proportional to the number of citrullinated residues in the peptide. Similarly, preincubation of carbamylated LL-37 with PAD2 abrogated the peptide's ability to bind DNA. Conversely, LL-37 with Arg residues substituted by homoarginine, which cannot be deiminated, elicited full activity of native LL-37 regardless of PAD2 treatment. Taken together, the data showed that citrullination abolished LL-37 ability to bind DNA and altered the immunomodulatory function of the peptide. Both activities were dependent on the proper distribution of guanidinium side chains in the native peptide sequence. Moreover, our data suggest that cathelicidin/LL-37 is citrullinated by PADs during NET formation, thus affecting the inflammatory potential of NETs. Together this may represent a novel mechanism for preventing the breakdown of immunotolerance, which is dependent on the response of APCs to self-molecules (including cell-free DNA); overactivation may facilitate development of autoimmunity.

• MeSH
• autoimunita imunologie   MeSH
• biologický transport MeSH
• buněčné linie MeSH
• citrulin metabolismus   MeSH
• citrulinace fyziologie   MeSH
• dendritické buňky imunologie   MeSH
• DNA imunologie   metabolismus   MeSH
• imunologická tolerance imunologie   MeSH
• kationické antimikrobiální peptidy metabolismus   MeSH
• lidé MeSH
• myši MeSH
• peptidylarginindeiminasy metabolismus   MeSH
• RAW 264.7 buňky MeSH
• volné cirkulující nukleové kyseliny imunologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH