Design, Synthesis and Evaluation of Branched RRWQWR-Based Peptides as Antibacterial Agents Against Clinically Relevant Gram-Positive and Gram-Negative Pathogens.

Multidrug resistance of pathogenic bacteria has become a public health crisis that requires the urgent design of new antibacterial drugs such as antimicrobial peptides (AMPs). Seeking to obtain new, lactoferricin B (LfcinB)-based synthetic peptides as viable early-stage candidates for future development as AMPs against clinically relevant bacteria, we designed, synthesized and screened three new cationic peptides derived from bovine LfcinB. These peptides contain at least one RRWQWR motif and differ by the copy number (monomeric, dimeric or tetrameric) and structure (linear or branched) of this motif. They comprise a linear palindromic peptide (RWQWRWQWR), a dimeric peptide (RRWQWR)2KAhx and a tetrameric peptide (RRWQWR)4K2Ahx2C2. They were screened for antibacterial activity against Enterococcus faecalis (ATCC 29212 and ATCC 51575 strains), Pseudomonas aeruginosa (ATCC 10145 and ATCC 27853 strains) and clinical isolates of two Gram-positive bacteria (Enterococcus faecium and Staphylococcus aureus) and two Gram-negative bacteria (Klebsiella pneumoniae and Pseudomonas aeruginosa). All three peptides exhibited greater activity than did the reference peptide, LfcinB (17-31), which contains a single linear RRWQWR motif. Against the ATCC reference strains, the three new peptides exhibited minimum inhibitory concentration (MIC50) values of 3.1-198.0 µM and minimum bactericidal concentration (MBC) values of 25-200 µM, and against the clinical isolates, MIC50 values of 1.6-75.0 µM and MBC values of 12.5-100 µM. However, the tetrameric peptide was also found to be strongly hemolytic (49.1% at 100 µM). Scanning Electron Microscopy (SEM) demonstrated that in the dimeric and tetrameric peptides, the RRWQWR motif is exposed to the pathogen surface. Our results may inform the design of new, RRWQWR-based AMPs.

A Tetrameric Peptide Derived from Bovine Lactoferricin Exhibits Specific Cytotoxic Effects against Oral Squamous-Cell Carcinoma Cell Lines.

Several short linear peptides derived from cyclic bovine lactoferricin were synthesized and tested for their cytotoxic effect against the oral cavity squamous-cell carcinoma (OSCC) cell lines CAL27 and SCC15. As a control, an immortalized and nontumorigenic cell line, Het-1A, was used. Linear peptides based on the RRWQWR core sequence showed a moderate cytotoxic effect and specificity towards tumorigenic cells. A tetrameric peptide, LfcinB(20-25)4, containing the RRWQWR motif, exhibited greater cytotoxic activity (>90%) in both OSCC cell lines compared to the linear lactoferricin peptide or the lactoferrin protein. Additionally, this tetrameric peptide showed the highest specificity towards tumorigenic cells among the tested peptides. Interestingly, this effect was very fast, with cell shrinkage, severe damage to cell membrane permeability, and lysis within one hour of treatment. Our results are consistent with a necrotic effect rather than an apoptotic one and suggest that this tetrameric peptide could be considered as a new candidate for the therapeutic treatment of OSCC.

Microesferas de PLGA: un sistema para la liberación controlada de moléculas con actividad inmunogénica / PLGA Microspheres: A controlled release system of molecules with immunogenic activity

En el campo de la tecnología farmacéutica se presenta actualmente considerable interés en el desarrollo de micropartículas biodegradables como un sistema para la liberación controlada de moléculas con actividad biológica. Son una buena alternativa, teniendo en cuenta que una de las principales desventajas de los productos disponibles es la necesidad de realizar varias administraciones para cumplir totalmente con el tratamiento. Esta contribución examina el papel actual de la microencapsulación de moléculas con actividad antigénica en microesferas elaboradas con polímeros biodegradables derivados de los ácidos láctico y glicólico (PLGA). Aquí se describen las propiedades fisicoquímicas de los biopolímeros empleados, los métodos de obtención de las micropartículas y de algunos de las variables que influyen en las propiedades del producto final. Además, se realiza una breve descripción del modo de acción propuesto para este sistema microparticular.

At the present time, there is a great interest in pharmaceutical technology focused on the development of biodegradable microparticles as a controlled release system of molecules with biological activity. This strategy arises as a good alternative; mainly if it is keep in mind that one of the principal disadvantages of the available products currently is that those products require several administrations to fulfilled the treatment. Here in is examined the role of microencapsulated antigens into microespheres performed with biodegradable copolymers derived from lactic and glycolic acid (PLGA). Physicochemical properties of biopolymers used, microspheres formulation as well as the parameters that affected the properties of the final product are also described. Additionally, there is a brief review of the action mechanism raised for this microparticular system.

Identification of three gp350/220 regions involved in Epstein-Barr virus invasion of host cells.

Epstein-Barr virus (EBV) invasion of B-lymphocytes involves EBV gp350/220 binding to B-lymphocyte CR2. The anti-gp350 monoclonal antibody (mAb)-72A1 Fab inhibits this binding and therefore blocks EBV invasion of target cells. However, gp350/220 regions interacting with mAb 72A1 and involved in EBV invasion of target cells have not yet been identified. This work reports three gp350/220 regions, defined by peptide 11382, 11389, and 11416 sequences, that are involved in EBV binding to B-lymphocytes. Peptides 11382, 11389, and 11416 bound to CR2(+) but not to CR2(-) cells, inhibited EBV invasion of cord blood lymphocytes (CBLs), were recognized by mAb 72A1, and inhibited mAb 72A1 binding to EBV. Peptides 11382 and 11416 binding to peripheral blood lymphocytes (PBLs) induced interleukin-6 protein synthesis in these cells, this phenomenon being inhibited by mAb 72A1. The same behavior has been reported for gp350/220 binding to PBLs. Anti-peptide 11382, 11389, and 11416 antibodies inhibited EBV binding and EBV invasion of PBLs and CBLs. Peptide 11382, 11389, and 11416 sequences presented homology with the C3dg regions coming into contact with CR2 (C3dg and gp350 bound to similar CR2 regions). These peptides could be used in designing strategies against EBV infection.