José Manuel Lozano

T cell recognition and therapeutic effect of a phosphorylated synthetic peptide of the 70K snRNP protein administered in MRL/lpr mice

Modifications of self antigens that occur during apoptosis might be involved in the generation of neo‐antigens, which can break tolerance and induce autoimmunity. We have previously identifiedan epitope at residues 131–151 of the U1‐70K snRNP protein, recognized by IgG antibodies and CD4+ T cells from at least two strains of lupus mice. With the aim of investigating the possible role of phosphorylation on the antigenicity of peptide 131–151 and to gain a better understanding of how this peptide can drive autoimmune response, we synthesized two peptides phosphorylated on Ser137 and 140, respectively. We show here that peptide P140 phosphorylated on Ser140 is recognized by both CD4+ T cells and antibodies from MRL/lpr mice. Furthermore, intravenous administration to lupus‐prone MRL/lpr mice of P140 in saline (but not of the non‐phosphorylated peptide) decreased proteinuria and anti‐DNA antibody production, and significantly prolonged survival of treated mice. We further demonstrated that P140 is recognized by antibodies from lupus patients and binds to various HLA DR molecules, offering new hope for manipulating T cell response in humans.

Leishmanicidal activity of synthetic antimicrobial peptides in an infection model with human dendritic cells.

Different species of Leishmania are responsible for cutaneous, mucocutaneous or visceral leishmaniasis infections in millions of people around the world [14]. The adverse reactions caused by antileishmanial drugs, emergence of resistance and lack of a vaccine have motivated the search for new therapeutic options to control this disease. Different sources of antimicrobial molecules are under study as antileishmanial agents, including peptides with antimicrobial and/or immunomodulatory activity, which have been considered to be potentially active against diverse species of Leishmania[7,39]. This study evaluated the cytotoxicity on dendritic cells, hemolytic activity, leishmanicidal properties on Leishmania panamensis and Leishmania major promastigotes and effectiveness on parasite intracellular forms (dendritic cells infected with L. panamensis and L. major promastigotes), when each parasite in culture was exposed to different concentrations of a group of synthetic peptides with previously reported antimicrobial properties, which were synthesized based on their naturally occurring reported sequences. Dermaseptin, Pr-2 and Pr-3 showed inhibitory activity on the growth of L. panamensis promastigotes, while Andropin and Cecropin A (with a selectivity index of 4 and 40, respectively) showed specific activity against intracellular forms of this species. The activities of Andropin and Cecropin A were exclusively against the intracellular forms of the parasite, therefore indicating the relevance of these two peptides as potential antileishmanial agents. In the case of L. major promastigotes, Melittin and Dermaseptin showed inhibitory activity, the latter also showed a selectivity index of 8 against intracellular forms. These findings suggest Andropin, Cecropin A and Dermaseptin as potential therapeutic tools to treat New and Old World cutaneous leishmaniasis.

Effect of temperature on partial molar volumes and viscosities of dilute aqueous solutions of 1-butanol, 1,2-butanediol, 1,4-butanediol, 1,2,4-butanetriol, and butanetetrol

Experimental densities and viscosities of dilute aqueous binary mixtures of 1-butanol, 1,2-butanediol, 1,4-butanediol, 1,2,4-butanetriol, and 1,2,3,4-butanetetrol (erythritol) were measured in the temperature range from 283.15 to 323.15 K. Apparent molar volumes were determined as a function of composition from density measurements. The limiting partial molar volumes of alcohols in aqueous solution were evaluated through extrapolation. The relative viscosity values were adjusted by least-squares to a second order equation to obtain the viscosity B coefficient which has been related to the size and shape of the solute molecule. The temperature dependence of the partial molar volume at infinite dilution and the viscosity B coefficient are discussed in terms of the relationship among polar and non polar groups on water structure and the effect of the position of hydroxyl groups in the molecule.

MSP-1 malaria pseudopeptide analogs: Biological and immunological significance and three-dimensional structure

Abstract Merozoite Surface Protein-1 (MSP-1) has been considered as a malaria vaccine candidate. It is processed during the Plasmodium falciparum invasion process of red blood cells (RBCs). A conserved MSP-1 C-terminal peptide was identified as a high-activity erythrocyte binding peptide (HAEBP) termed 1585. Since conserved HAEBPs are neither antigenic nor immunogenic we decided to assess the significance of a single peptide bond replacement in 1585. Thus, two pseudopeptides were obtained by introducing a ψ[CH2-NH] reduced amide isoster into the 1585 critical binding motif. The pseudopeptides bound to different HLA-DR alleles, suggesting that backbone modifications affect MHC-II binding patterns. Pseudopeptide antibodies inhibit in vitro parasite RBC invasion by recognizing MSP-1. Each pseudopeptide-induced antibody shows distinct recognition patterns. 1H-NMR studies demonstrated that isoster bonds modulate the pseudopeptides structure and thus their immunological properties, therefore representing a possible subunit malaria vaccine component.

Biological activity of secondary metabolites from Peltostigma guatemalense

Leaves and wood of Peltostigma guatemalense, a novel species of the family Rutaceae, yielded a total of 14 secondary metabolites, i.e. methyl p-hydroxy benzoate, phenylacetic acid, β-sitosterol, lupeol, syringaresinol, scopoletin, gardenin B (1), and seven alkaloids: γ-fagarine (2), skimmianine (3), kokusaginine (4), 7-O-isopentenyl-γ-fagarine (5), anhydro-evoxine (6), evoxine (7) and 4-methoxy-1-methyl-quinolin-2-one (8). The compounds have been identified by spectroscopic methods. Antibacterial and antimalarial in vitro activity of the isolated compounds were also determined. Methyl p-hydroxy benzoate and quinolone (8) were the most effective on Plasmodium falciparium strains.

Development of Designed Site-Directed Pseudopeptide-Peptido-Mimetic Immunogens as Novel Minimal Subunit-Vaccine Candidates for Malaria

Synthetic vaccines constitute the most promising tools for controlling and preventing infectious diseases. When synthetic immunogens are designed from the pathogen native sequences, these are normally poorly immunogenic and do not induce protection, as demonstrated in our research. After attempting many synthetic strategies for improving the immunogenicity properties of these sequences, the approach consisting of identifying high binding motifs present in those, and then performing specific changes on amino-acids belonging to such motifs, has proven to be a workable strategy. In addition, other strategies consisting of chemically introducing non-natural constraints to the backbone topology of the molecule and modifying the α-carbon asymmetry are becoming valuable tools to be considered in this pursuit. Non-natural structural constraints to the peptide backbone can be achieved by introducing peptide bond isosters such as reduced amides, partially retro or retro-inverso modifications or even including urea motifs. The second can be obtained by strategically replacing L-amino-acids with their enantiomeric forms for obtaining both structurally site-directed designed immunogens as potential vaccine candidates and their Ig structural molecular images, both having immuno-therapeutic effects for preventing and controlling malaria.

A chimeric protein-based malaria vaccine candidate induces robust T cell responses against Plasmodium vivax MSP119

The most widespread Plasmodium species, Plasmodium vivax, poses a significant public health threat. An effective vaccine is needed to reduce global malaria burden. Of the erythrocytic stage vaccine candidates, the 19 kDa fragment of the P. vivax Merozoite Surface Protein 1 (PvMSP119) is one of the most promising. Our group has previously defined several promiscuous T helper epitopes within the PvMSP1 protein, with features that allow them to bind multiple MHC class II alleles. We describe here a P. vivax recombinant modular chimera based on MSP1 (PvRMC-MSP1) that includes defined T cell epitopes genetically fused to PvMSP119. This vaccine candidate preserved structural elements of the native PvMSP119 and elicited cytophilic antibody responses, and CD4+ and CD8+ T cells capable of recognizing PvMSP119. Although CD8+ T cells that recognize blood stage antigens have been reported to control blood infection, CD8+ T cell responses induced by P. falciparum or P. vivax vaccine candidates based on MSP119 have not been reported. To our knowledge, this is the first time a protein based subunit vaccine has been able to induce CD8+ T cell against PvMSP119. The PvRMC-MSP1 protein was also recognized by naturally acquired antibodies from individuals living in malaria endemic areas with an antibody profile associated with protection from infection. These features make PvRMC-MSP1 a promising vaccine candidate.

A New Approach to Obtaining N α-t-Boc-Amino Acid Aldehydes from Asparagine and Glutamine for Reduced Amide Pseudopeptide Solid-Phase Synthesis

Reduced amide pseudopeptides have been proposed as structural probes that could be useful as potential malarial vaccine components. However, designing determined pseudopeptide sequences containing isoster peptide bonds, either on an asparagine (Asn) or on a glutamine (Gln) residues, can become difficult because these precursor amino acid aldehydes are obtained in yields lower than 0.5%. This work presents a new strategy for obtaining both Asn and Gln aldehydes based on a controlled side‐chain protection approach as well as a suitable solvent partition procedure. FT‐IR, 1H‐NMR and 13C‐NMR were used for molecule characterization and identification. Amino acid aldehydes were successfully incorporated into a 20‐mer peptide from a malarial‐relevant sequence, and their impact on the molecule’s conformational properties was assessed.

Estudio fitoquímico de hojas de Uncaria guianensis y evaluación de actividad antibacteriana

A chlorin compound, pheophorbide a ethyl ester and a mixture of sterols known as β-sitosterol and stigmasterol, were isolated from the petroleum ether extract of Uncaria guianensis (Rubiaceae) leaves. Their structures were elucidated by detailed analysis of NMR spectra, including bidimensional techniques and by comparison with literature data. The antibacterial activity for the pheophorbide a ethyl ester was evaluated against two Gram (+) strains: S. aureus ATCC 6538 y E. faecalis ATCC 29212 and three Gram (-) strains: E. coli ATCC 25922, S. typhimurium ATCC 14028s y S. typhimurium MS7953S. aureus ATCC 6538 and E. fecalis ATCC 29212, finding significant activity against S. aureus 6538, E. faecalis 29212, S. tiphymurium MS7953 and E. coli 25922.

GGRGDSPCA Peptide: A New Antiscarring Agent on Glaucoma Filtration Surgery

BACKGROUND AND OBJECTIVE GGRGDSPCA synthetic peptide competes for integrin receptor in scar formation after glaucoma filtering surgery in a rabbit model. The purpose of this study was to evaluate the use of this peptide and compare it with mitomycin on glaucoma filtering surgery. MATERIALS AND METHODS Posterior sclerectomy was performed in both eyes of 17 rabbits. The right eye received GGRGDSPCA (p605) at 0, 4, 8, 12, and 16 days after. Nine left eyes received saline as a control; the remaining 8 eyes received mitomycin C at 0.5 mg/mL intraoperative. Intraocular pressures and biomicroscopy were evaluated as well as bleb function. RESULTS Intraocular pressure decreased significantly in both the peptide and mitomycin treated eyes in comparison with the saline group (P = 0.0003). Pressure was similar in both groups. The blebs showed filtrating function in a functional analysis at day 21 and 41 in the mitomycin cases as well as in the peptide group. Histologic analysis performed in both peptide and mitomycin groups showed inhibitory effect in fibrocellular and collagen organization with bleb formation. CONCLUSIONS The p605 peptide showed to be similar to mitomycin C in controlling and improving glaucoma filtering surgery in rabbits. This alternative may potentially be useful for similar purposes in humans for the control of glaucoma and improvement of filtering surgery.