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Kiadins are in silico designed peptides with a strong similarity to diPGLa-H, a tandem sequence of PGLa-H (KIAKVALKAL) and with single, double or quadruple glycine substitutions. They were found to show high variability in their activity and selectivity against Gram-negative and Gram-positive bacteria, as well as cytotoxicity against host cells, which are influenced by the number and placing of glycine residues along the sequence. The conformational flexibility introduced by these substitutions contributes differently peptide structuring and to their interactions with the model membranes, as observed by molecular dynamics simulations. We relate these results to experimentally determined data on the structure of kiadins and their interactions with liposomes having a phospholipid membrane composition similar to simulation membrane models, as well as to their antibacterial and cytotoxic activities, and also discuss the challenges in interpreting these multiscale experiments and understanding why the presence of glycine residues in the sequence affected the antibacterial potency and toxicity towards host cells in a different manner.

Alginate-based hydrogels with tunable mechanical properties are developed by chemical methylation of the polysaccharide backbone, which was performed either in homogeneous phase (in solution) or in heterogeneous phase (on hydrogels). Nuclear Magnetic Resonance (NMR) and Size Exclusion Chromatography (SEC-MALS) analyses of methylated alginates allow to identify the presence and location of methyl groups on the polysaccharide, and to investigate the influence of methylation on the stiffness of the polymer chains. The methylated polysaccharides are employed for the manufacturing of calcium-reticulated hydrogels for cell growth in 3D. The rheological characterization shows that the shear modulus of hydrogels is dependent on the amount of cross-linker used. Methylated alginates represent a platform to explore the effect of mechanical properties on cell activity. As an example, the effect of compliance is investigated using hydrogels displaying similar shear modulus. An osteosarcoma cell line (MG-63) was encapsulated in the alginate hydrogels and the effect of material compliance on cell proliferation and localization of YAP/TAZ protein complex is investigated by flow cytometry and immunohistochemistry, respectively. The results point out that an increase of material compliance leads to an increase of the proliferative rate of cells and correlates with the translocation of YAP/TAZ inside the cell nucleus.

Breast cancer (BC) is the primary cause of cancer mortality in women and the triple-negative breast cancer (TNBC) is the most aggressive subtype characterized by poor differentiation and high proliferative properties. High mobility group A1 (HMGA1) is an oncogenic factor involved in the onset and progression of the neoplastic transformation in BC. Here, we unraveled that the replication-dependent-histone (RD-HIST) gene expression is enriched in BC tissues and correlates with HMGA1 expression. We explored the role of HMGA1 in modulating the RD-HIST genes expression in TNBC cells and show that MDA-MB-231 cells, depleted of HMGA1, express low levels of core histones. We show that HMGA1 participates in the activation of the HIST1H4H promoter and that it interacts with the nuclear protein of the ataxia-telangiectasia mutated locus (NPAT), the coordinator of the transcription of the RD-HIST genes. Moreover, we demonstrate that HMGA1 silencing increases the percentage of cells in G0/G1 phase both in TNBC and epirubicin resistant TNBC cells. Moreover, HMGA1 silencing causes an increase in epirubicin IC50 both in parental and epirubicin resistant cells thus suggesting that targeting HMGA1 could affect the efficacy of epirubicin treatment.

COVID-19, the severe acute respiratory syndrome, is one of the major emergencies that have affected health care systems. Drugs and oxygen are only partially effective in saving lives in patients with severe COVID-19, and the most important protection from death is vaccination. The widespread use of COVID-19 adenovirus-based vaccines has provided evidence for the occurrence of rare venous thrombotic events including cerebral venous thrombosis and splanchnic venous thrombosis in recipients of Vaxzevria and Jcovden vaccines and the review focus on them. One year ago, thromboses in Vaxzevria recipients have been associated with thrombocytopenia in the presence of antibodies to platelet factor 4 and have been called vaccine-induced immune thrombotic thrombocytopenia (VITT). The incidence of VITT is equal to 9-31 events per one million doses of vaccines as evaluated by health agencies worldwide and is higher in female and young vaccine recipients. More recently, by using the European EudraVigilance database, it has been demonstrated that the incidence of thrombosis in recipients of adenovirus-based vaccines is 5–10 fold higher than that of VITT and 7–12 fold higher than observed in the recipients of Comirnaty, an mRNA-based vaccine, suggesting that adenovirus-based vaccines cause not only VITT but also thrombosis without thrombocytopenia (non-VITT thrombosis). The incidence of the vaccine-dependent non-VITT thrombosis is different in the adenovirus-based vaccines and the VITT/non-VITT incidence ratio depends on the severity of thrombosis and is inversely related to the age of the recipients. The possible causes and clinical implications of non-VITT thrombosis in vaccine recipients are discussed.

Mussels (Mytilus spp.) tolerate infections much better than other species living in the same marine coastal environment thanks to a highly efficient innate immune system, which exploits a remarkable diversification of effector molecules involved in mucosal and humoral responses. Among these, antimicrobial peptides (AMPs) are subjected to massive gene presence/absence variation (PAV), endowing each individual with a potentially unique repertoire of defense molecules. The unavailability of a chromosome-scale assembly has so far prevented a comprehensive evaluation of the genomic arrangement of AMP-encoding loci, preventing an accurate ascertainment of the orthology/paralogy relationships among sequence variants. Here, we characterized the CRP-I gene cluster in the blue mussel Mytilus edulis, which includes about 50 paralogous genes and pseudogenes, mostly packed in a small genomic region within chromosome 5. We further reported the occurrence of widespread PAV within this family in the Mytilus species complex and provided evidence that CRP-I peptides likely adopt a knottin fold. We functionally characterized the synthetic peptide sCRP-I H1, assessing the presence of biological activities consistent with other knottins, revealing that mussel CRP-I peptides are unlikely to act as antimicrobial agents or protease inhibitors, even though they may be used as defense molecules against infections from eukaryotic parasites.

As bioactive small proteins with antimicrobial and immunomodulatory activities that are naturally produced by all living organisms, antimicrobial peptides (AMPs) have a marked potential as next-generation antibiotics. However, their development as antibacterial agents is limited by low stability and cytotoxicity. D-BMAP18, a membrane-permeabilizing antimicrobial peptide composed of D-amino acids, has shown good antibacterial and anti-inflammatory activities but also a non-negligible cytotoxicity against eukaryotic cell lines. In this study, a prodrug has been developed that extends the peptide with a negatively charged, inactivating sequence containing the cleavage site for neutrophil elastase (NE). The ultimate goal was to allow the activation of D-BMAP18 by endogenous elastase only at the site of infection/inflammation, enabling a slow and targeted release of the pharmacologically active peptide. In vitro activation of Pro-D-BMAP18 was confirmed using purified NE. Its antimicrobial and cytotoxic activities were tested in the presence and absence of elastase and compared to those of the parental form. The prodrug had minimal activity in the absence of elastase, while its proteolysis product retained an appreciable antimicrobial activity but lower cytotoxicity. Moreover, Pro-D-BMAP18 was found to be correctly converted to D-BMAP18 in the presence of CF sputum as a model of the lung environment and showed good antimicrobial activity under these conditions.

The ChAdOx1 nCoV-19 (ChA) (AstraZeneca) and Ad26.COV2.S (AD26) (Janssen) vaccines are virus-based coronavirus disease 2019 (COVID-19) vaccines used worldwide. In spring 2021, venous blood clots and thrombocytopenia were described in some vaccine recipients. We evaluated the frequency of severe adverse events (SAEs) documented in the EudraVigilance European database in young adult (18-64 years old) and older (≥65 years old) vaccine recipients up to 23 June 2021 and related them to coagulation disorders and arterial, cardiac, and nervous system events. Comparison between the frequency of SAEs and SAE-related deaths in ChA and AD26 vs. BNT162b2 COVID-19 (BNT) (Pfizer/BioNTech) vaccine recipients demonstrated: 1) ChA and AD26 recipients than BNT recipients had higher frequencies of not only SAEs caused by venous blood clots and hemorrhage, but also thromboembolic disease and arterial events, including myocardial infarction and stroke; 2) a corresponding higher frequency of SAE-related deaths. The frequency was higher in both young adults and older adults. Comparison between the frequency of SAEs and SAE-related deaths in AD26 vs. ChA recipients demonstrated in AD26 recipients: 1) lower frequency of thrombocytopenia; 2) lower frequency of SAEs in young adult recipients; 3) higher frequency of SAEs in older recipients. Interestingly, most of the venous thrombotic SAEs associated with ChA and AD26 vaccines were not associated with thrombocytopenia, suggesting that TTS (thrombosis with thrombocytopenia syndrome) is not the only type of thrombosis observed following virus-based vaccines. In conclusion, both virus-based COVID-19 vaccines show more SAEs than BNT, but the frequency of the SAE type in the different age groups differs, suggesting that the mechanisms responsible of SAEs overlap only partly.

Bivalve mollusks are continuously exposed to potentially pathogenic microorganisms living in the marine environment. Not surprisingly, these filter- feeders developed a robust innate immunity to protect themselves, which includes a broad panel of antimicrobial peptides. Among these, myticalins represent a recently discovered family of linear cationic peptides expressed in the gills of Mytilus galloprovincialis. Even though myticalins and insect and mammalian proline-rich antimicrobial peptides (PrAMPs) share a similar amino acid composition, we here show that none of the tested mussel peptides use a non-lytic mode of action relying on the bacterial transporter SbmA. On the other hand, all the tested myticalins perturbed and permeabilized the membranes of E. coli BW25113, as shown by flow-cytometry and atomic force microscopy. Circular dichroism spectra revealed that most myticalins did not adopt recognizable secondary structures in the presence of amphipathic environments, such as biological membranes. To explore possible uses of myticalins for biotech, we assessed their biocompatibility with a human cell line. Non- negligible cytotoxic effects displayed by myticalins indicate that their optimization would be required before their further use as lead compounds in the development of new antibiotics.

This study reports the identification of four novel proline-rich antimicrobial peptides (PR-AMP) from the transcriptome of the red swamp crayfish Procambarus clarkii. The newly identified putative peptides (PcAst- 1b, -1c, −2 and −3), which are related with the previously identified hemocyte-specific PR-AMP astacidin-1, are encoded by the multi-genic astacidin gene family. The screening of available and proprietary transcriptomes allowed to define the taxonomical range of distribution of this gene family to Astacoidea and Parastacoidea. The antimicrobial properties of three synthetic PcAst peptides (PcAst-1a, -1b/c and −2), were characterized against reference bacteria or multidrug resistant clinical isolates, and their cytotoxicity was evaluated towards human transformed cell lines. The antimicrobial activity ranged from potent and broad- spectrum, in low-salt medium, to poor, whereas it was generally low in full nutrient broth. No significant toxic effects were observed on cultured human cells. RNA-seq data from 12 different tissues indicated a strong specificity for haemocytes under naïve physiological condition, with moderate expression (5-fold lower) in gills. Quantitative real time PCR revealed a rapid (within 2 h) and significant up-regulation of PcAst-1a (Astacidin 1) and PcAst-2 expression in response to LPS injection. Due to the variation in antimicrobial potency and inducibility, the roles of the other astacidins (PcAst-1b, -1c and −3) need to be further investigated to determine their significance to the immune responses of the red swamp crayfish.

The human cathelicidin hCAP18/LL-37 has become a paradigm for the pleiotropic roles of peptides in host defence. It has a remarkably wide functional repertoire that includes direct antimicrobial activities against various types of microorganisms, the role of 'alarmin' that helps to orchestrate the immune response to infection, the capacity to locally modulate inflammation both enhancing it to aid in combating infection and limiting it to prevent damage to infected tissues, the promotion of angiogenesis and wound healing, and possibly also the elimination of abnormal cells. LL-37 manages to carry out all its reported activities with a small and simple, amphipathic, helical structure. In this review we consider how different aspects of its primary and secondary structures, as well as its marked tendency to form oligomers under physiological solution conditions and then bind to molecular surfaces as such, explain some of its cytotoxic and immunomodulatory effects. We consider its modes of interaction with bacterial membranes and capacity to act as a pore-forming toxin directed by our organism against bacterial cells, contrasting this with the mode of action of related peptides from other species. We also consider its different membrane-dependent effects on our own cells, which underlie many of its other activities in host defence. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.

The increasing emergence of multidrug-resistant microorganisms represents one of the greatest challenges in the clinical management of infectious diseases, and requires the development of novel antimicrobial agents. To this aim, we de novo designed a library of Arg-rich ultra-short cationic antimicrobial lipopeptides (USCLs), based on the Arg-X-Trp-Arg-NH 2 peptide moiety conjugated with a fatty acid, and investigated their antibacterial potential. USCLs exhibited an excellent antimicrobial activity against clinically pathogenic microorganisms, in particular Gram-positive bacteria, including multidrug resistant strains, with MIC values ranging between 1.56 and 6.25 μg/mL. The capability of the two most active molecules, Lau-RIWR-NH 2 and Lau-RRIWRR-NH 2 to interact with the bacterial membranes has been predicted by molecular dynamics and verified on liposomes by surface plasmon resonance. Both compounds inhibited the growth of S. aureus even at sub MIC concentrations and induced cell membranes permeabilization by producing visible cell surface alterations leading to a significant decrease in bacterial viability. Interestingly, no cytotoxic effects were evidenced for these lipopeptides up to 50–100 μg/mL in hemolysis assay, in human epidermal model and HaCaT cells, thus highlighting a good cell selectivity. These results, together with the simple composition of USCLs, make them promising lead compounds as new antimicrobials.

Gold nanoparticles (AuNPs) covered with mixtures of immiscible ligands present potentially anisotropic surfaces that can modulate their interactions at complex nano–bio interfaces. Mixed, self-assembled, monolayer (SAM)-protected AuNPs, prepared with incompatible hydrocarbon and fluorocarbon amphiphilic ligands, are used here to probe the molecular basis of surface phase separation and disclose the role of fluorinated ligands on the interaction with lipid model membranes and cells, by integrating in silico and experimental approaches. These results indicate that the presence of fluorinated amphiphilic ligands enhances the membrane binding ability and cellular uptake of gold nanoparticles with respect to those coated only with hydrogenated amphiphilic ligands. For mixed monolayers, computational results suggest that ligand phase separation occurs on the gold surface, and the resulting anisotropy affects the number of contacts and adhesion energies with a membrane bilayer. This reflects in a diverse membrane interaction for NPs with different surface morphologies, as determined by surface plasmon resonance, as well as differential effects on cells, as observed by flow cytometry and confocal microscopy. Overall, limited changes in monolayer features can significantly affect NP surface interfacial properties, which, in turn, affect the interaction of SAM-AuNPs with cellular membranes and subsequent effects on cells.

Antimicrobial peptides (AMPs) are naturally produced, gene encoded molecules with a direct antimicrobial activity against pathogens, often also showing other immune-related properties. Anuran skin secretions are rich in bioactive peptides, including AMPs, and we have reported a novel targeted sequencing approach to identify novel AMPs simultaneously in different frog species, from small quantities of skin tissue. Over a hundred fulllength peptides were identified from specimens belonging to five different Ranidae frog species, out of which 29 were novel sequences. Six of these were selected for synthesis and testing against a panel of Gram-negative and Gram-positive bacteria. One peptide, identified in Rana arvalis, proved to be a potent and broad-spectrum antimicrobial, active against ATCC bacterial strains and a multi-drug resistant clinical isolate. CD spectroscopy suggests it has a helical conformation, while surface plasmon resonance (SPR) that it may self-aggregate/oligomerize at the membrane surface. It was found to disrupt the bacterial membrane at sub-MIC, MIC and above- MIC concentrations, as observed by flow cytometry and/or visualized by atomic force microscopy (AFM). Only a limited toxicity was observed towards peripheral blood mononuclear cells (PBMC) with a more pronounced effect observed against the MEC-1 cell line.

Mutations in NCSTN gene (encoding for nicastrin protein) are associated with hidradenitis suppurativa (HS), a chronic inflammatory disease involving hair follicles. HS is clinically handled with drugs but the most severe cases are treated with surgery. Photobiomodulation (PBM) therapy, already used in the treatment of skin diseases such as acne, herpes virus lesions, ultraviolet damage, vitiligo, hypertrophic scar, keloid, burn, psoriasis and diabetic chronic wounds, could be beneficial as an adjuvant supportive treatment to promote and foster the healing process after skin excision in HS. The effects of PBM therapy in promoting the wound closure are evaluated in a HaCaT cells NCSTN-/-, assessing cell metabolism, migration rate, proliferation and cell cycle progression. In our experimental model, PBM exerts a potent action on metabolism of mutated keratinocytes, incrementing adenosine triphosphate (ATP) production at 2 hours, while after 24 hours an increase of metabolism with a decrement of intracellular ATP levels were recorded. Moreover, PBM speeds up the wound closure, inducing cells' migration without affecting their proliferation.Based on our findings, we suggest the use of PBM in HS patients, who undergo major surgery with large skin excision.

LL‐37 is an innate immune peptide derived from the human cathelicidin, which exerts pleiotropic roles in host defense and healing. These activities in part depend on its capacity to adopt an amphipathic helical structure in physiological solutions and then oligomerizing. Orthologues from other primates, such as rhesus RL‐37, remain monomeric and disordered under the same conditions. Intramolecular salt‐bridges, arising from appropriately spaced anionic and cationic residues in its sequence, may play a relevant role in determining the particular structure adopted by LL‐37. To probe this, we have effected minimal, targeted residue variations such as replacement of a single residue (K15→G), or inversion of one or both sets of two residues (E10 K11→ K10 E11 or E16 K18→ K16 E18). This could alter the pattern of intramolecular salt bridging without affecting other functionally relevant parameters such as overall hydrophobicity, helix amphipathicity or charge. The structural and functional effects were analyzed using CD spectroscopy, surface plasmon resonance, antimicrobial activity assays, and bacterial membrane permeabilization to fluorescent probes of increasing sizes, using flow cytometry. Analogs were functionally different from both LL‐37 and RL‐37, so it was not possible to switch from the function of one to that of the other simply by altering the salt‐bridging pattern in this manner. This indicates that the particular structure/function characteristics of LL‐37 likely depend quite subtly, and in a precise and complex manner, on a complex pattern of intramolecular interactions.

Unlike most antimicrobial peptides (AMPs), the main mode of action of the subclass of proline-rich antimicrobial peptides (PrAMPs) is not based on disruption of the bacterial membrane. Instead, PrAMPs exploit the inner membrane transporters SbmA and YjiL/MdtM to pass through the bacterial membrane and enter the cytosol of specific Gram-negative bacteria, where they exert an inhibitory effect on protein synthesis. Despite sharing a high proline and arginine content with other characterized PrAMPs, the PrAMP Bac5 has a low sequence identity with them. Here we investigated the mode of action of three N-terminal Bac5 fragments, Bac5(1-15), Bac5(1-25), and Bac5(1-31). We show that Bac5(1-25) and Bac5(1-31) retained excellent antimicrobial activity toward Escherichia coli and low toxicity toward eukaryotic cells, whereas Bac5(1-15) was inactive. Bac5(1-25) and Bac5(1-31) inhibited bacterial protein synthesis in vitro and in vivo . Competition assays suggested that the binding site of Bac5 is within the ribosomal tunnel, where it prevents the transition from the initiation to the elongation phase of translation, as reported for other PrAMPs, such as the bovine PrAMP Bac7. Surprisingly, unlike Bac7, Bac5(1-25) exhibited species-specific inhibition, being an excellent inhibitor of protein synthesis on E. coli ribosomes but a poor inhibitor on Thermus thermophilus ribosomes. This indicates that while Bac5 most likely has an overlapping binding site with Bac7, the mode of interaction is distinct, suggesting that Bac5 fragments may be interesting alternative lead compounds for the development of new antimicrobial agents.

Molecular self-assembly is a topic attracting intense scientific interest. Various strategies have been developed for construction of molecular aggregates with rationally designed properties, geometries, and dimensions that promise to provide solutions to both theoretical and practical problems in areas such as drug delivery, medical diagnostics, and biosensors, to name but a few. In this respect, gold nanoparticles covered with self-assembled monolayers presenting nanoscale surface patterns—typically patched, striped or Janus-like domains—represent an emerging field. These systems are particularly intriguing for use in bio-nanotechnology applications, as presence of such monolayers with three-dimensional (3D) morphology provides nanoparticles with surface-dependent properties that, in turn, affect their biological behavior. Comprehensive understanding of the physicochemical interactions occurring at the interface between these versatile nanomaterials and biological systems is therefore crucial to fully exploit their potential. This review aims to explore the current state of development of such patterned, self-assembled monolayer-protected gold nanoparticles, through step-by-step analysis of their conceptual design, synthetic procedures, predicted and determined surface characteristics, interactions with and performance in biological environments, and experimental and computational methods currently employed for their investigation.

The spread of antibiotic resistant-pathogens is driving the search for new antimicrobial compounds. Pulmonary infections experienced by cystic fibrosis (CF) patients are a dramatic example of this health-care emergency. Antimicrobial peptides could answer the need for new antibiotics but translating them from basic research to the clinic is a challenge. We have previously evaluated the potential of the small membranolytic peptide BMAP-18 to treat CF-related infections, discovering that while this molecule had a good activity in vitro it was not active in vivo because of its rapid degradation by pulmonary proteases. In this study, we synthesized and tested the proteases-resistant all-D enantiomer. In spite of a good antimicrobial activity against Pseudomonas aeruginosa and Stenotrophomonas maltophilia clinical isolates and of a tolerable cytotoxicity in vitro, D-BMAP18 was ineffective to treat P. aeruginosa pulmonary infection in mice, in comparison to tobramycin. We observed that different factors other than peptide degradation hampered its efficacy for pulmonary application. These results indicate that D-BMAP18 needs further optimization before being suitable for clinical application and this approach may represent a guide for optimization of other anti-infective peptides eligible for the treatment of pulmonary infections.

Biofilm matrices of two Klebsiella pneumoniae clinical isolates, KpTs101 and KpTs113, were investigated for their polysaccharide composition and protective effects against antimicrobial peptides. Both strains were good biofilm producers, with KpTs113 forming flocs with very low adhesive properties to supports. Matrix exopolysaccharides were isolated and their monosaccharide composition and glycosidic linkage types were defined. KpTs101 polysaccharide is neutral and composed only of galactose, in both pyranose and furanose ring configurations. Conversely, KpTs113 polysaccharide is anionic due to glucuronic acid units, and also contains glucose and mannose residues. The susceptibility of the two strains to two bovine cathelicidin antimicrobial peptides, BMAP-27 and Bac7(1–35), was assessed using both planktonic cultures and biofilms. Biofilm matrices exerted a relevant protection against both antimicrobials, which act with quite different mechanisms. Similar protection was also detected when antimicrobial peptides were tested against planktonic bacteria in the presence of the polysaccharides extracted from KpTs101 and KpTs113 biofilms, suggesting sequestering adduct formation with antimicrobials. Circular dichroism experiments on BMAP-27 in the presence of increasing amounts of either polysaccharide confirmed their ability to interact with the peptide and induce an alpha-helical conformation.

β-Defensins are antimicrobial peptides that exert their host-defence functions at the interface between the host and microbial biota. They display a direct, salt- and medium-sensitive cidal activity, in vitro, against a broad spectrum of bacteria and fungi, and there is increasing evidence that they also play a role in alerting and enhancing cellular components of innate and adaptive immunity. Their interaction with biological membranes plays a central role in both of these types of activities. In the present study, we have investigated the interaction of fluorescently labelled hBD2 (human β-defensin 2) with monocytes, macrophages and iDCs (immature dendritic cells), observing a differential capacity to be rapidly internalized into these cells. Complementary microscopy techniques [TEM (transmission electron microscopy), optical microscopy and IR microspectroscopy] were used to explore the functional and biological implications of these interactions on iDCs. Short-term exposure to the peptide resulted in significant alterations in membrane composition and re-organization of the endomembrane system, with the induction of degranulation. These events may be associated with the antigen-presenting activities or the chemotaxis of iDCs, which appears to occur via both CCR6 (CC chemokine receptor 6)-dependent and -independent mechanisms.

International audience; Amphotericin B (AMB) has long been considered the most effective drug in the treatment of serious invasive fungal infections. There are, however, major limitations to its use, due to several adverse effects, including acute infusional reactions and, most relevant, a dose-dependent nephrotoxicity. At least some of these effects are attributed to the aggregation of AMB as a result of its poor water solubility. To overcome this problem, reformulated versions of the drug have been developed, including a micellar dispersion of AMB with sodium deoxycholate (AMBD), its encapsulation into liposomes, or its incorporation into lipidic complexes. The development of nanobiotechnologies provides novel potential drug delivery systems that make use of nanomaterials such as functionalized carbon nanotubes (f-CNTs), which are emerging as an innovative and efficient tool for the transport and cellular translocation of therapeutic molecules. In this study, we prepared two conjugates between f-CNTs and AMB. The antifungal activity of these conjugates was tested against a collection of reference and clinical fungal strains, in comparison to that of AMB alone or AMBD. Measured minimum inhibition concentration (MIC) values for f-CNT-AMB conjugates were either comparable to or better than those displayed by AMB and AMBD. Furthermore, AMBD-resistant Candida strains were found to be susceptible to f-CNT-AMB 1. Additional studies, aimed at understanding the mechanism of action of the conjugates, suggest a nonlytic mechanism, since the compounds show a major permeabilizing effect on the tested fungal strains only after extended incubation. Interestingly, the f-CNT-AMB 1 does not show any significant toxic effect on Jurkat cells at antifungal concentrations.

A role for mast cells (MC) in the pathogenesis of multiple sclerosis (MS) has been suggested, based on the analysis of human lesions and on an animal model of the disease (EAE). What role MC play in the development of MS is not well understood. We hypothesized that the link connecting MC with demyelinating diseases may be represented by their interaction with myelin. Here we show that myelin can activate mast cells. This process could be a key event in the mast cell function required for inducing EAE in mice and possibly in MS in man.

β-Defensins play an important role in both innate and adaptive immunity, displaying a direct anti-microbial activity against a wide variety of micro-organisms as well as interesting immuno-modulatory effects on host cells. Interaction with biological membranes appears to be a central theme in modulating these activities, leading to different consequences such as membrane lysis, translocation into the cytoplasm or transfer to a receptor. We have investigated the structuring of human β-defensins (hBD2 and hBD3) and rationally designed variants, in relation to their interactions with real and model membranes. Biophysical methods, such as circular dichroism (CD), transmission or reflection IR and dye release were used to probe their structure/activity in the presence of model membranes, while fluorimetric and flow cytometric assays were used to investigate the effects on prokaryotic cells. Our results indicate that structural features, such as the helical N-terminal domains and oligomerisation at the membrane surface, may modulate the efficiency of membrane insertion and selectivity for microbial or host-cell membranes. We propose that both peptides interact with membranes as extended β-sheet platforms that present amphipathic helices for insertion into the lipid bilayer. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.

The ruthenium-based drug imidazolium trans-imidazoledimethylsulphoxidetetrachlorido ruthenate (NAMI-A) is a novel antitumour drug under clinical evaluation. In this study, NAMI-A is tested on aortic rings in vitro and on the systolic blood pressure in vivo with the aim of evaluating its effects on smooth muscle cells and, more in general, on the vascular system. Pre-incubation of aortic rings with 10 µM NAMI-A for 10 min potentiates the contraction induced by phenylephrine (PE). The reduction of the B max value of [(3)H]-prazosin bound to NAMI-A-treated aortic rings and the ability of NAMI-A to displace [(3)H]-prazosin and [(3)H]-IP3 binding by 25 and 42%, respectively, suggest the involvement of α1-adrenoceptor in mediating the effects on smooth muscle cells. NAMI-A also decreases the number of maximal sites of [(3)H]-prazosin bound to kidney membrane preparation from 34 to 24 fmol/mg proteins. A single i.p. dose (105 mg/kg) or a repeated treatment for 6 consecutive days (17 mg/kg/day) in Wistar rats increases the systolic blood pressure, respectively, 1 h and 3 days after treatment, and the responsiveness of rat aortic rings to PE. Atomic absorption spectroscopy confirms the presence of ruthenium in the aortic rings excised from the treated rats. These findings suggest monitoring the cardiovascular parameters when the drug is used in humans for treating cancer patients, particularly if the drug is associated with chemicals that are potentially active at the cardiovascular level.

Cathelicidin genes homologous to the human CAMP gene, coding for the host defense peptide LL-37, have been sequenced and analyzed in 20 primate species, including Great Apes, hylobatidae, cercopithecidae, callithricidae, and cebidae. The region corresponding to the putative mature antimicrobial peptide is subject to a strong selective pressure for variation, with evidence for positive selection throughout the phylogenetic tree relating the peptides, which favors alterations in the charge while little affecting overall hydrophobicity or amphipathicity. Selected peptides were chemically synthesized and characterized, and two distinct types of behavior were observed. Macaque and leaf-eating monkey RL-37 peptides, like other helical antimicrobial peptides found in insect, frog, and mammalian species, were unstructured in bulk solution and had a potent, salt and medium independent antimicrobial activity in vitro, which may be the principal function also in vivo. Human LL-37 and the orangutan, hylobates, and callithrix homologues instead showed a salt-dependent structuring and likely aggregation in bulk solution that affected antimicrobial activity and its medium dependence. The two types of peptides differ also in their interaction with host cells. The evolution of these peptides has thus resulted in distinct mechanisms of action that affect the direct antimicrobial activity and may also modulate accessory antimicrobial functions due to interactions with host cells.

Host defense peptides (HDPs) are endogenous antibiotics that play a multifunctional role in the innate immunity of mammals. Among these, βdefensins contribute to mucosal and epithelial defense, also acting as signal molecules for cellular components of innate and adaptive immunity. Numerous members of this family have been identified in mammalian and avian species, and genomic studies in human and mouse indicate a considerable complexity in their gene organization. Recent reports on the evolution of primate and rodent members of this family indicate quite a complex pattern of variation. In this review we briefly discuss the evolution of mammalian βdefensins in relation to other types of defensins, and then concentrate on the evolution of βdefensins 1 to 4 in primates. In particular, the surprisingly varied patterns of evolution, which range from neutral or weakly purifying, to positive selection to a high level of conservation are analyzed in terms of possible genetics, structural or functional implications, as well as to observed variations on the antimicrobial activity in vitro. The role of polymorphisms in the genes encoding for these host defense peptides in determining susceptibility to human diseases are also briefly considered.

The coordination of the antimetastatic agent NAMI-A, [H(2)im][trans-RuCl(4)(dmso-S)(Him)], (Him=imidazole; dmso=dimethyl sulfoxide), to the DNA model base 9-methyladenine (9-MeAde) was investigated in water. NMR spectroscopy was first applied for the study of the molecular stability and hydrolysis of NAMI-A in aqueous solution over a range of pH (3.0-7.4) and chloride ion concentrations (0-1 M) at 37.0 degrees C. In physiological conditions (phosphate buffer, pH 7.4) NAMI-A disappears from the solution in 15 min due to chloride and dmso hydrolysis, leading to uncharacterised poly-oxo Ru species. Conversely, at lower pH (3.0-6.0) and in water (pH approximately 5.5), only a partial dmso hydrolysis occurs, slowly forming the [trans-RuCl(4)(H(2)O)(Him)](-) complex. This latter species coordinates to 9-MeAde (via the N7 of 9-MeAde), forming the [trans-RuCl(4)(9-MeAde)(Him)](-) complex. NAMI-A and [trans-RuCl(4)(H(2)O)(Him)](-) give comparable intracellular ruthenium concentrations and accumulate in KB cells (human mouth carcinoma) and accumulate these at the G(2)/M phase, while poly-oxo Ru species do not, and their cell uptake is reduced to 50%. On the contrary, G(2)/M arrest and protein content in the murine metastatic cell line metGM, are not influenced by NAMI-A hydrolysis. Hydrolysed NAMI-A species apparently are easier taken up by the metGM cells, showing intracellular ruthenium concentrations one order of magnitude greater than those of intact NAMI-A. Therefore, it is proposed that the selective antimetastatic activity of NAMI-A during in vivo experiments can be attributed to its hydrolysed species.

The human cathelicidin peptide LL-37 is an important effector of our innate immune system and contributes to host defence with direct antimicrobial activity and immunomodulatory properties, and by stimulating wound healing. Its sequence has evolved to confer specific structural characteristics that strongly affect these biological activities, and differentiate it from orthologues of other primate species. In the present paper we report a detailed study of the folding and self-assembly of this peptide in comparison with rhesus monkey peptide RL-37, taking into account the different stages of its trajectory from bulk solution to contact with, and insertion into, biological membranes. Phenylalanine residues in different positions throughout the native sequences of LL-37 and RL-37 were systematically replaced with the non-invasive fluorescent and IR probe p-cyanophenylalanine. Steady-state and time-resolved fluorescence studies showed that LL-37, in contrast to RL-37, forms oligomers with a loose hydrophobic core in physiological solutions, which persist in the presence of biological membranes. Fourier transform IR and surface plasmon resonance studies also indicated different modes of interaction for LL-37 and RL-37 with anionic and neutral membranes. This correlated with a distinctly different mode of bacterial membrane permeabilization, as determined using a flow cytometric method involving impermeant fluorescent dyes linked to polymers of defined sizes.

Two fullerene derivatives (fullerenes1and2), bearing a hydrophilic chain on the pyrrolidinic nitrogen, were developed with the aim to deliver anticancer agents to solid tumors. These two compounds showed a significantly different behaviour on human neoplastic cell linesin vitroin respect to healthy leukocytes. In particular, the pyrrolidinium ring on the fullerene carbon cage brings to a more active compound. In the present work, we describe the effects of these fullerenes on primary cultures of human monocytes and macrophages, two kinds of immune cells representing the first line of defence in the immune response to foreign materials. These compounds are not recognized by circulating monocytes while they get into macrophages. The evaluation of the pronecrotic or proapoptotic effects, analysed by means of analysis of the purinergic receptor P2X7 activation and of ROS scavenging activity, has allowed us to show that fullerene2, but not its analogue fullerene1, displays toxicity, even though at concentrations higher than those shown to be active on neoplastic cells.

The antimicrobial activity of a regular and decaffeinated Arabica coffee extract was evaluated against three different Gram-positive bacteria and two Gram-negatives, including pathogenic Staphylococci strains. The antimicrobial activity was shown to be independent from caffeine content and was more pronounced against the Gram-positive strains. The regular coffee extract exhibited a significant bacteriostatic effect against Staphylococcus aureus and Staphylococcus epidermidis at short exposure times and became bactericidal after prolonged exposure. The potential cytotoxicity of the regular coffee extract was also evaluated towards breast adenocarcinoma MCF7 cells, showing to become significant only after 24 h exposure and at a higher concentration than that producing the antibacterial effect. These results highlight the potential of coffee extracts as a naturally active and non-toxic antibacterial compound suitable for biomedical applications.

Apoptosis is a strictly regulated cell death mechanism that plays a pivotal role in the normal evolution of multicellular organisms. Its misregulation has been associated with many diseases, making its early and reliable detection a key point for modern cellular biology. In this paper, we propose the use of infrared microspectroscopy (IRMS) as a label-free methodology for the detection of apoptotic-related biochemical processes induced on U937 leukemic monocytes by serum starvation and CCCP-exposure. The spectroscopic results are in agreement with parallel Flow Cytometry (FC) experiments, where plasma membrane integrity and mitochondrial activity were assessed. Spectroscopic outcomes complement FC data and allow drawing a more complete picture of the apoptotic pathways. In particular, we established that the two apoptosis-inducing treatments, cell starvation and CCCP exposure, affect the cell cycle in a different way. With the former, cell death is preceded by a cell cycle arrest, whereas the latter causes an increased cell cycle progression. Spectral data demonstrate that for both conditions apoptosis proceeds through the accumulation of lipid droplets within cells. Moreover, we were able to establish a spectral marker for DNA condensation/ fragmentation: the enhancement of the PhI band component centred at similar to 1206 cm(-1), which is more sensitive than the relative intensity of the PhII band to which phospholipids and carbohydrates also contribute significantly. In conclusion, we demonstrate that the intrinsic multi-parametric nature of IRMS and its application on cells under physiological conditions can be well exploited for the investigation of apoptotic pathways.

Bac7(1-35) is an active fragment of the bovine cathelicidin antimicrobial peptide Bac7, which selectively inactivates Gram-negative bacteria both in vitro and in mice infected with Salmonella typhimurium. It has a non-lytic mechanism of action, is rapidly internalized by susceptible bacteria and mammalian cells and likely acts by binding to internal targets. In this study we show that Bac7(1-35) accumulates selectively within primed macrophages with respect to resting monocytes. Confocal microscopy analysis showed that the peptide mainly distributes in the cytoplasm and perinuclear region of macrophages within 3 hours of incubation, without affecting cell viability. Cytotoxicity studies showed that the peptide does not induce necrotic or apoptotic damage up to concentrations 50-100-fold higher than minimal inhibitory concentrations (MIC). Moreover, Bac7(1-35) did not affect the ability of macrophages to engulf S. typhimurium, a species that may proliferate within this cell type. Conversely, when added to macrophages after phagocytosis, Bac7(1-35) caused a significant reduction in the number of recovered bacteria, indicating that it can kill the engulfed microorganisms directly and/or indirectly, via activation of the defense response of the cells.

LL-37 is a multifunctional component of innate immunity, with a membrane-directed antimicrobial activity and receptor-mediated pleiotropic effects on host cells. Sequence variations in its primate orthologues suggest that two types of functional features have evolved; human LL-37-like peptides form amphipathic helical structures and self-assemble under physiological conditions, whereas rhesus RL-37-like peptides only adopt this structure in the presence of bacterial membranes. The first type of peptide has a lower and more medium-sensitive antimicrobial activity than the second type, but an increased capacity to stimulate host cells. Oligomerization strongly affects the mode of interaction with biological membranes and, consequently, both cytotoxicity and receptor-mediated activities. In the present study we explored the effects of LL-37 self-association by using obligate disulfide-linked dimers with either parallel or antiparallel orientations. These had an increased propensity to form stacked helices in bulk solution and when in contact with either anionic or neutral model membranes. The antimicrobial activity against Gram-positive or Gram-negative bacteria, as well as the cytotoxic effects on host cells, strongly depended on the type of dimerization. To investigate the extent of native oligomerization we replaced Phe5 with the photoactive residue Bpa (p-benzoyl-L-phenylalanine), which, upon UV irradiation, enabled covalent cross-linking and allowed us to assess the extent of oligomerization in both physiological solution and in model membranes.

The ruthenium-based compound imidazolium trans-imidazoledimethylsulfoxide-tetrachlororuthenate (NAMI-A) is free of cytotoxicity up to 1. mM concentration after 1. h in vitro exposure of the LLC-PK1 renal tubule cells. In vivo, one cycle of i.p. administrations of 35. mg/kg/day NAMI-A (1. cycle. =. 6 consecutive days), is free of a measurable toxicity on mouse kidneys. After two cycles with a one-week drug-free washout between cycles, mitochondrial membrane potential of the renal cells drops by 37% (p

The interest on functionalized fullerenes in the field of nanomedicine has seen a significant increase in the past decade. However, the different methods employed to increase C60 solubility profoundly influence the physicochemical properties and the toxicological effects of these compounds, thus complicating the evaluation of their toxicity and potential therapeutic use. Here we report a whole-transcriptome RNA-seq analysis assessing the effect of two fullerenes (1 and 2) on gene expression in the human MCF7 cell line. Although these two compounds had previously been characterized by in vitro studies as having a cytotoxic and null effect respectively, to date the mechanisms at the basis of this different behavior and, more in general, at the basis of the effect of most fullerene derivatives in living cells are still completely unknown. Our data evidence that: (a) fullerene 2 caused a significant, time-dependent alteration of gene expression, whereas 1 only had a negligible effect; (b) the biological processes mostly influenced over the 48. h experimental time course were transcription, protein synthesis, cell cycle progression and cell adhesion; (c) the gene expression signature of 2-treated cells was strikingly similar to those induced by selective inhibitors of mTOR signaling, thus suggesting an effect on this pathway for fullerene 2.Our work represents the first approach toward the application of RNA-seq to the study of the molecular mechanisms underlying the interaction of fullerenes with cellular systems and provides an objective view of the feasibility and the safety of these nanomaterials for a medical application.

Fullerenes (C60) represent important carbon nanoparticles, widely investigated for diagnostic and therapeutic uses, mainly because they are characterized by a small size (between 7 and 10 A ˚ ) and a large surface area. The cytotoxicity of two fullerene derivatives, functionalized by 1,3-dipolar cycloaddition of azome- thine ylides to the C60 cage (1 and 2), the mechanism of cellular uptake (studied with a fluorescein-bearing derivative of 1, hereafter called derivative 3), and the intracellular distribution are the subject of this work. Cell cytotoxicity on human mammary carcinoma cell line (MCF7), evaluated with the MTT test and further confirmed by a flow cytometry approach with DiOC6 and PI probes, showed that derivative 1 was free of necrotic or apoptotic effects even after a long lasting cell exposure. Cell uptake and internalization of derivative 3 reach their zenith within 12 h after treatment, with a tendency to persist up to 72 h; this process was evaluated by flow cytometry and confirmed by confocal micros- copy. Thus, it appears that a compound such as derivative 1 may be unspecif ically taken up by MCF7 cells, in which it distributes throughout the cytoplasm, apparently avoiding any co-localization within the nucleus and secretory granules. These results suggest a strong interaction between the tested fullerene and mammalian cells and a significant ability of this compound to enter tumor cells, therefore resulting to be a suitable vector to deliver anticancer agents to tumor cells.

In this paper we report a review of the results obtained in the last few years by our group in the development of ruthenium(III) complexes characterized by the presence of sulfoxide ligands and endowed with antitumor properties. In particular, we will focus on ruthenates of general formula Na[trans-RuCl4(R1R2SO)(L)], where R1R2SO = dimethylsulfoxide (DMSO) or tetramethylenesulfoxide (TMSO) and L = nitrogen donor ligand. The chemical behavior of these complexes has been studied by means of spectroscopic techniques both in slightly acidic distilled water and in phosphate buffered solution at physiological pH. The influence of biological reductants on the chemical behavior is also described. The antitumor properties have been investigated on a number of experimental tumors. Out of the effects observed, notheworthy appears the capability of the tested ruthenates to control the metastatic dissemination of solid metastasizing tumors. The analysis of the antimetastatic action, made in particular on the MCa mammary carcinoma of CBA mouse, has demonstrated a therapeutic value for these complexes which are able to significantly prolong the survival time of the treated animals. The antimetastatic effect is not attributable to a specific cytotoxicity for metastatic tumor cells although in vitro experiments on pBR322 double stranded DNA has shown that the test ruthenates bind to the macromolecule, causing breaks corresponding to almost all bases, except than thymine, and are able to cause interstrand bonds, depending on the nature of the complex being tested, some of which results active as cisplatin itself.

The effects of lysozyme (hen egg-white lysozyme) on lymphocytes harvested from mice bearing MCa mammary carcinoma were tested at the daily dose of 100 mg/kg given orally for 10 consecutive days. With this experimental paradigm that consists of a significant reduction of lung metastasis formation, lysozyme was seen to be capable of stimulating the recovery of the response to ConA of mononuclear cells, reduced by tumor growth; this effect was particularly evident with splenocytes and GALT lymphocytes. The effects of lysozyme depended: (i) on the presence of plastic adherent cells, (ii) at least in in vitro experiments, on the amount of lysozyme used, being higher at the dose of 250 mug/ml of incubation mixture, and (iii) on the time of challenge with lysozyme. These effects were shown either by measuring the [H-3]-thymidine incorporation into DNA or by application of the sulphorhodamine test for protein synthesis. After in vivo treatment, lysozyme significantly modified the histological architecture of the mucosal immunity of the gut, by causing a significant reduction of the number of the lymphatic nodules placed immediately under the layer of epithelial cells of villi. At the same time no significant modification of Peyer's patches was noted. Together these data stress the role of lysozyme in the modulation of host immunity and, in particular, point out the relevance of the mucosal immunity of the gut as first target for lysozyme activity.

A new biological response modifier, L-(adamant-2-yl)glycyl-L-alanyl-D-isoglutamine hydrochloride (AdTP), recently synthesized and characterized for antitumor, antiviral and immunomodulating properties was studied in comparison to the peptidoglycan monomer (PGM) isolated from Brevibacterium divaricatum to test the effects of their use concomitant to that of anticancer cytotoxic drugs such as cyclophosphamide, 5-fluorouracil (5-FU), cisplatin and 4-(3,3-dimethyl-1-triazeno)-5-carboxamide (dacarbazine). The experiments, performed using both Lewis lung carcinoma and MCa mammary carcinoma of CBA mouse, indicated that: a) the cytotoxic drugs, used at the maximum tolerated doses, caused different degrees of reduction of the tumors; b) the same drugs reduced lung metastases with greater efficacy when treatments were applied at the early stages of metastasis formation; c) AdTP, similarly to PGM confirmed its ability to increase some immunological parameters of lymphocytes obtained from the spleens of the treated mice; d) AdTP increased the effects of 5-FU on lung metastases but failed to show any increase of life expectancy with any treatment performed. These data indicate that AdTP, although increasing some functional responses of lymphocytes in vitro, does not improve the therapeutic activity of cyclophosphamide, cisplatin, 5-FU and dacarbazine in the experimental models presently used.

First experiments demonstrating the suitability of novel microfabricated fluidic devices for measuring living cells in physiological environment by synchrotron radiation (SR) Fourier Transform Infrared microspectroscopy (μ-FTIR) are presented. The devices were fabricated on CaF 2 windows, using the photoresist XARP 3100/10 to define the liquid cell lay-out. Therefore, the sample holder is transparent to both visible and infrared light, robust, completely recyclable and with a precise spacing. Using prototype devices of thicknesses 9, 5 and 3 μm, we studied the response of the U937 monocytic cell line to mechanical compression. The temporal evolution of the FTIR spectra, characteristic for the status of living cells, was used to monitor the cellular system stability in time. Protein biosynthesis and lipid metabolism alterations upon deformation have been identified by monitoring specific cell band ratios such as amide I to amide II, amide I to lipids, methylene to methyl and asymmetric to symmetric stretching of phosphates. Taking advantage of the high brilliance of the synchrotron radiation, chemical maps of monocyte cells were collected, demonstrating the versatility of the device.

Here we present the optimization of fabrication steps for realizing an infrared-visible microfluidic chip to study single-living cell behaviour in physiological environment by synchrotron radiation FTIR microspectroscopy. We optimized subtractive and additive lithographic processes on CaF"2 substrate, employing X-ARP 3100/10 photoresist both as etching-mask and for the device fabrication. Using prototype microfabricated liquid cells 9 and [email protected] thick, we measured the response of small groups of THP1 monocytic cells to mechanical compression and chemical stimulation with fMLP using conventional IR globar source, aiming to evaluate biochemical rearrangements of leukocytes during the capillary circulation or recruitment processes. Stimulated monocytes have spectral features recognizable, differentiating them from un-stimulated, especially affecting the spectral region 1280-1000cm^-^1, characteristic of nucleic acids and carbohydrates, and specific band ratios, such as proteins on lipids and methylene on methyl. Spectra variations have been correlated with biochemical events such as transcription, synthesis of new-proteins and variations in membrane fluidity.

A group of 23 patients, affected by malignant diseases (n = 21) or suffering from inflammatory diseases (n = 2) and characterised by a general reduction in total lymphocytes and an altered CD4+: CD8+ ratio (mainly low), were enrolled in a phase II clinical trial studying the effect of oral treatment with lysozyme chloride. The cancer patients were mainly in complete remission (19 of 21) after anticancer treatment, but 2 had drug unmaintained stable minimal disease. Lysozyme treatment, 2 g/day for periods up to longer than 90 days, was started after a washout period of at least 60 days after chemotherapy.

The effects of two new Ru(III) complexes, [mer-RuCl3(DMSO)2Im] degrees and Na[trans-RuCl4(DMSO)Im], were investigated on primary tumor growth and on the survival time using three solid metastasizing tumors of the mouse: Lewis lung carcinoma, B16 melanoma and MCa mammary carcinoma. Na[trans-RuCl4(DMSO)Im] appears to be the most promising compound, in that: (1) it is soluble in water and therefore easy to handle in comparison with the neutral species [mer-RuCl3(DMSO)2Im]degrees or to the already described BBR2382; (2) similarly to cisplatin, though at a lower level, it reduces tumor growth in its primary site in each tumor model employed; (3) unlike cisplatin, it increases the life span of tumor-bearing hosts in all tumors used, independently of the effects on primary tumor growth; and (4) it is also effective in reducing spontaneous metastasis formation when the effects on primary tumor growth are completely absent. Dimethylsulfoxide (DMSO), used for solubilizing poorly water-soluble compounds (i.e. [mer-RuCl3(DMSO)2Im]degrees) or for stabilizing the compound in the solution before injection (i.e. Na[trans-RuCl4(DMSO)Im]), reduces the anti-tumor potency. Conversely, the antitumor effects of Na[trans-RuCl4(DMSO)Im] are more pronounced in mice hydrated with isotonic saline. We conclude that Na[trans-RuCl4(DMSO)Im] is a good candidate for further investigations aimed at ascertaining the mechanism of the anti-metastatic activity and of the positive effects on survival time of mice bearing solid metastasizing tumors.

We have designed and chemically synthesized an artificial β-defensin based on a minimal template derived from the comparative analysis of over 80 naturally occurring sequences. This molecule has the disulfide-bridged β-sheet core structure of natural β-defensins and shows a robust salt-sensitive antimicrobial activity against bacteria and yeast, as well as a chemotactic activity against immature dendritic cells. An SAR (structure–activity relationship) study using two truncated fragments or a Cys→Ser point-mutated analogue, from which one or two of the three disulfide bridges were absent, indicated that altering the structure resulted in a different type of membrane interaction and a switch to different modes of action towards both microbial and host cells, and that covalent dimerization could favour antimicrobial activity. Comparison of the structural, aggregational and biological activities of the artificial defensin with those of three human β-defensins and their primate orthologues provided useful information on how their mode of action may relate to specific structural features.

Aim: To investigate the effect of different growth conditions on Bacillus cereus cell and spore properties. Methods and Results: Bacillus cereus was grown on agar plates with different surface water conditions (wet and dry) or viscosity. Cell populations displayed different types of behaviour, and heterogeneity was manifested in cell motility and dimension. Spore populations were heterogeneous regarding their properties, namely size and thermal resistance. The smallest spores were produced from flagellated cells, which also displayed jet-motility, growing on the wettest agar. Cytometric analysis also revealed within the smallest spores a sub-population labelled by propidium iodide (PI), indicating that spore populations were partly damaged. Nonmotile cells grown on diffusion-limiting media were elongated and produced the least thermal-resistant spores. Conclusions: The micro-structural properties of the media were found to influence cell and spore properties. Abundant surface water enabled flagellar motility and resulted in a heterogeneous cell and spore population, the latter including small and damaged spores. High viscosity gave rise to filamentous cells and more heat-sensitive spores. Significance and Impact of the Study: This study provides useful information on conditions resulting in heterogeneous populations of damaged and heat-sensitive spores.

In this paper, we describe a rapid flow cytometry method to identify antimicrobial peptides that are internalized into bacterial cells and differentiate them from those that are membrane active. The method was applied to fluorescently labeled Bac7 1-35 and polymyxin B, whose mechanisms of action are, respectively, based on cell penetration and on membrane binding and permeabilization. Identification of peptides with the former mechanism is of considerable interest for the intracellular delivery of membrane-impermeant drugs.

The human cathelicidin LL-37 displays both direct antibacterial activities and the capacity to modulate host-cell activities. These depend on structural characteristics that are subject to positive selection for variation, as observed in a previous analysis of the CAMP gene (encoding LL-37) in primates. The altered balance between cationic and anionic residues in different primate orthologues affects intramolecular salt-bridging and influences the stability of the helical conformation and tendency to aggregate in solution of the peptide. In the present study, we have analysed the effects of these structural variations on membrane interactions for human LL-37, rhesus RL-37 and orang-utan LL-37, using several complementary biophysical and biochemical methods. CD and ATR (attenuated total reflection)-FTIR (Fourier-transform IR) spectroscopy on model membranes indicate that RL-37, which is monomeric and unstructured in bulk solution [F-form (free form)], and human LL-37, which is partly structured and probably aggregated [A-form (aggregated form)], bind biological membranes in different manners. RL-37 may insert more deeply into the lipid bilayer than LL-37, which remains aggregated. AFM (atomic force microscopy) performed on the same supported bilayer as used for ATR-FTIR measurements suggests a carpet-like mode of permeabilization for RL37 and formation of more defined worm-holes for LL-37. Comparison of data from the biological activity on bacterial cells with permeabilization of model membranes indicates that the structure/aggregation state also affects the trajectory of the peptides from bulk solution through the outer cell-wall layers to the membrane. The results of the present study suggest that F-form cathelicidin orthologues may have evolved to have primarily a direct antimicrobial defensive capacity, whereas the A-forms have somewhat sacrificed this to gain host-cell modulating functions.

The antitumor and antimetastatic effects of p-(3-methyl-1-triazeno)benzoic acid potassium salt (MM-COOK) as compared with those of the parent 3,3-dimethyl derivative (DM-COOK) were examined using Lewis lung carcinoma, MCa mammary carcinoma of the CBA mouse and TLX5 lymphoma. Similarly to DM-COOK, MM-COOK reduces metastasis formation and significantly prolongs the survival of mice bearing the Lewis lung carcinoma when given at a daily dose corresponding to one-half that of DM-COOK. Unlike DM-COOK, MM-COOK exhibits significant cytotoxicity to metastatic foci and pronounced inhibition of primary tumor development. MM-COOK also causes cytotoxic effects on TLX5 lymphoma cell growing in the peritoneal cavity, even when used at low doses. The antimetastatic effects observed in mice bearing MCa mammary carcinoma are unrelated to the inhibition of primary tumor growth and are more likely due to the selection of clones endowed with lower metastatic ability. It appears that MM-COOK exhibits the same antineoplastic activity as DM-COOK, but the former does so at a lower daily dose and produces interesting cytotoxic effects other than those reflecting its antimetastatic properties. It thus seems to be a valid alternative to DM-COOK, in view of the possible introduction of newer aryltriazenes into clinical use.

Galectin-1 is a 14 kDa beta-galactoside binding protein, capable of forming lattice-like structures with glycans of cellular glycoconjugates and inducing intracellular signaling. The expression of Galectin-1 in porcine cartilage is described in this work for the first time. Immunocytochemical methods revealed distinct distribution patterns for both articular and growth plate cartilage. In articular cartilage, the highest reactivity for Galectin-1 was found in all chondrocytes at the superficial zone and in most of those at the lower layer of the middle zone. In the growth plate, marked reactivity was seen in chondrocytes at the proliferative zone and reached a maximum level for the column-forming cells at the hypertrophic zone. In addition, different Galectin-1 distribution patterns were observed at the subcellular level. With regards to the metabolic effects of Galectin-1, the results in vitro seem to indicate an inhibitory effect of Galectin-1 on articular chondrocyte anabolism (i.e. inhibition of cell proliferation and anabolic gene expression) and a stimulation of catabolic processes (i.e. induction of matrix degradation and hypertrophy marker expression). These data represent a starting point for the understanding the molecular mechanisms underlining ECM-Galectin-1 interaction and the subsequent signaling-cell transduction processes involving cartilage formation and maturation.