Carlos Cossio (1903-1987)

Fil: Vilanova, José Manuel. Universidad de Buenos Aires. Facultad de Derecho. Cátedra Teoría General y Filosofía del Derecho. Buenos Aires, Argentin

High variability of gene expression in S. epidermidis biofilm population

In the past two decades S. epidermidis has emerged from a commensal microorganism into a predominant opportunistic pathogen associated with nosocomial infections due to the ability to adhere to abiotic surfaces and form biofilms. The increasing use of indwelling medical devices has influenced the rise of S. epidermidis to a major medical research topic. S. epidermidis biofilms are well known to be resistant to both the host immune response and antimicrobial therapy, making these infections hard to treat and often resulting in recurrent infections. To better understand why biofilms have evolved in this manner, many comparative studies have been performed using biofilms and planktonic cultures. However, since biofilm cultures are fundamentally different from planktonic cultures, some concerns have been raised in the past for such studies. While it seems reasonable to compare biofilm cultures with stationary planktonic cultures, recently it has been suggested that biofilms cultures could be compared directly to the bacteria in suspension, grown in the vicinity of the biofilms. Nevertheless and however interesting, this suggestion fails to accommodate the fact that mature biofilms will release bacteria from within the biofilm to the suspension. This phenomenon was suggested to be responsible for colonization of further niches. Therefore, such population can both contain biofilm outbound bacteria as well as plantkonic free floating bacteria. In an attempt to better understand the possible differences between cell populations, we selected 5 distinct bacterial isolates previously characterized for biofilm formation and compared the expression of some genes of interest, namely atlE (involved in initial adhesion) and icaA (involved immune evasion and biofilm maturation). Three populations were characterized: (1) late exponential planktonic cultures grown on Erlenmeyer flasks, (2) biofilm populations attached to polystyrene 24-well culture plates and (3) the bacteria grown in suspension on the same well of culture plates as the biofilms (non-adherent cells), all grown in TSB supplemented with 0,4% glucose. Differences in the gene expression profile were observed between S. epidermidis strains. The icaA expression values were generally higher in biofilms as compared with planktonic cultures. However, when comparing with the non-adherent cells grown in the vicinity of the biofilms, some strain to strain variation was observed, as in some cases the non-adherent cells has lower icaA expression but in other instances the opposite occurred. A similar effect occurred with atlE expression. A possible explanation for the higher variation on the non-adherent cells has to do with the washing step required before resuspending the biofilm: while more tenacious biofilm forming strains will withstand better the washing step, some weaker biofilm forming strains will be washed away. In the latter cases the bacterial population described as non-adherent cells will be very heterogeneous. Thus, with the variation found in the non-adherent bacteria, it seems that in order to study the physiological differences that occur when bacteria are living in a biofilm, planktonic cultures grown independently of biofilms should be used to better understand the pathophysiology of the biofilm-related infections

Polymeric nanogels as vaccine delivery systems

Polymeric nanogels find a relevant field of application in the formulation of a new generation of therapeutic and preventive vaccines, aiming at the fine-tuned modulation of the immune response. Intrinsic properties of polymeric nanogels, such as material chemistry, size and shape, surface charge, and hydrophobicity or hydrophilicity, may be determining factors in shaping the induced immune response. These materials can thus work as synthetic adjuvants, which can also be conjugated with immunostimulants. Polymeric nanogels protect vaccine antigens from degradation in vivo and, surface-conjugated with antibodies or specific ligands, could increase active targeting specificity. This review covers the recent published data concerning the modulation of innate and adaptive immune responses by engineered polymeric nanogels and their potential application as delivery systems in vaccination.S.A. Ferreira is the recipient of a fellowship from International Iberian Nanotechnology Laboratory (INL)

The generalist inside the specialist: gut bacterial communities of two insect species feeding on toxic plants are dominated by enterococcus sp.

Some specialist insects feed on plants rich in secondary compounds, which pose a major selective pressure on both the phytophagous and the gut microbiota. However, microbial communities of toxic plant feeders are still poorly characterized. Here, we show the bacterial communities of the gut of two specialized Lepidoptera, Hyles euphorbiae and Brithys crini, which exclusively feed on latex-rich Euphorbia sp. and alkaloid-rich Pancratium maritimum, respectively. A metagenomic analysis based on high-throughput sequencing of the 16S rRNA gene revealed that the gut microbiota of both insects is dominated by the phylum Firmicutes, and especially by the common gut inhabitant Enterococcus sp. Staphylococcus sp. are also found in H. euphorbiae though to a lesser extent. By scanning electron microscopy, we found a dense ring-shaped bacterial biofilm in the hindgut of H. euphorbiae, and identified the most prominent bacterium in the biofilm as Enterococcus casseliflavus through molecular techniques. Interestingly, this species has previously been reported to contribute to the immobilization of latex-like molecules in the larvae of Spodoptera litura, a highly polyphagous lepidopteran. The E. casseliflavus strain was isolated from the gut and its ability to tolerate natural latex was tested under laboratory conditions. This fact, along with the identification of less frequent bacterial species able to degrade alkaloids and/or latex, suggest a putative role of bacterial communities in the tolerance of specialized insects to their toxic diet.Financial support was provided by grant BFU2012-39816-C02-01 (Ministerio de Ciencia e Innovación, Spain) co-financed by FEDER funds to Amparo Latorre and CGL2008-00605 (Ministerio de Ciencia e Innovación) to Joaquín Baixeras. Cristina Vilanova is a recipient of a FPU fellowship from the Ministerio de Educación (Spain).Peer reviewe

Supramolecular assembled nanogel made of mannan

Introduction: The supramolecular assembled nanogel made of mannan was synthesed and characterized with the purpose to obtain a potential pharmaceutical delivery system able to work both as a therapeutic and prophylactic vaccine adjuvant and antigen carrier. These systems are expected to perform as carriers for proteins and peptides, acting like antigens, optimizing delivery to antigen-presenting cells, by targeting their mannose receptors. Immunity might be improved conjugating this system with other immune response modifiers.info:eu-repo/semantics/publishedVersio

Inflammatory cell recruitment in Candida glabrata biofilm cell-infected mice receiving antifungal chemotherapy

(1) Background: Due to a high rate of antifungal resistance, Candida glabrata is one of the most prevalent Candida spp. linked to systemic candidiasis, which is particularly critical in catheterized patients. The goal of this work was to simulate a systemic infection exclusively derived from C. glabrata biofilm cells and to evaluate the effectiveness of the treatment of two echinocandinscaspofungin (Csf) and micafungin (Mcf). (2) Methods: CD1 mice were infected with 48 h-biofilm cells of C. glabrata and then treated with Csf or Mcf. After 72 h, the efficacy of each drug was evaluated to assess the organ fungal burden through colony forming units (CFU) counting. The immune cell recruitment into target organs was evaluated by flow cytometry or histopathology analysis. (3) Results: Fungal burden was found to be higher in the liver than in the kidneys. However, none of the drugs was effective in completely eradicating C. glabrata biofilm cells. At the evaluated time point, flow cytometry analysis showed a predominant mononuclear response in the spleen, which was also evident in the liver and kidneys of the infected mice, as observed by histopathology analysis. (4) Conclusions: Echinocandins do not have a significant impact on liver and kidney fungal burden, or recruited inflammatory infiltrate, when mice are intravenously (i.v.) infected with C. glabrata biofilm-grown cells.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of the Norte 2020 - Programa Operacional Regional do Norte, financially supported by project UID/EQU/00511/2019 — Laboratory for Process Engineering, Environment, Biotechnology and Energy (LEPABE) funded by national funds through FCT/MCTES (PIDDAC), Célia F. Rodrigues’ (SFRH/BD/93078/20130) PhD grant and M. Elisa Rodrigues (SFRH/BPD/95401/2013) post-doc grant.info:eu-repo/semantics/publishedVersio

Mice infection with Candida glabrata biofilm cells: inflammatory cell recruitment and antifungal treatment efficacy

Background: Candida glabrata is one of the most widespread Candida spp. associated to systemic candidiasis. This species is particularly critical in hospitalized, catheterized and immunosuppressed patients, due to a high drug resistance, specially to the azoles, but also to the ability to rapidly develop echinocandin resistance. Objectives: The goal of this work was to simulate a systemic infection exclusively derived from C. glabrata biofilm cells and to evaluate the effectiveness of two echinocandins caspofungin (Csf) and micafungin (Mcf) - in its treatment. The host-pathogen response was also studied, by analyzing the inflammatory cell recruitment. Methods: CD1 mice were infected exclusively with 48 h-biofilm cells of C. glabrata and then treated with Csf or Mcf. After 72h, the efficacy of each drug was evaluated assessing organ fungal burden through CFU counting. Moreover, the immune cell recruitment into target organs was evaluated by flow cytometry and histopathology analysis. Results: Fungal burden was higher in the liver than in the kidneys. Nevertheless, none of the drugs was effective in eradicating completely the infection. At the evaluated time point, flow cytometry analysis, showed a predominant mononuclear response in the spleen, which was also evident in liver and kidneys of the infected mice, as observed by the histopathology analysis. Together, these observations confirmed C. glabrata as a low inflammatory species and indicated that two-dose treatment with Csf and Mcf do not have a significant impact on liver and kidney fungal burden, or recruited inflammatory infiltrate, when mice are i.v. infected with C. glabrata biofilm-grown cells.info:eu-repo/semantics/publishedVersio

Towards Staphylococcus epidermidis biofilm dormancy characterization

Book of Abstracts of CEB Annual Meeting 2017info:eu-repo/semantics/publishedVersio