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Abstract: Increasing awareness of the relevance of Streptococcus dysgalactiae ssp. equisimilis as a human pathogen motivates the analysis of its pathomechanisms. One of the mechanisms that increases infectivity and dissemination of several streptococcal species is the recruitment and subsequent activation of host plasminogen on the streptococcal surface. This study identified GCS3 as a novel plasminogen-binding M protein of S. dysgalactiae ssp. equisimilis and revealed a difference in the mode of binding as compared to the plasminogen-binding protein PAM of S. pyogenes. In contrast to PAM, GCS3 did not bind to the kringle 1–3 region of plasminogen. Despite this difference, GCS3 exerts the same function of recruiting plasminogen to the streptococcal surface, which can be activated by streptokinase and host plasminogen activators to serve as a spreading factor. Moreover, we demonstrate a role of GCS3 in plasminogen-dependent streptococcal adherence to human pharyngeal cells (cell line Detroit 562) that indicates an additional function of the protein as an adhesin in the oral cavity. [ABSTRACT FROM AUTHOR]

Subversion of the plasminogen activation system is implicated in the virulence of group A streptococci (GAS). GAS displays receptors for the human zymogen plasminogen on the cell surface, one of which is the plasminogen-binding group A streptococcal M-like protein (PAM). The plasminogen binding domain of PAM is highly variable, and this variation has been linked to host selective immune pressure. Site-directed mutagenesis of full-length PAM protein from an invasive GAS isolate was undertaken to assess the contribution of residues in the a1 and a2 repeat domains to plasminogen binding function. Mutagenesis to alanine of key plasminogen binding lysine residues in the a1 and a2 repeats (Lys98 and Lys111) did not abrogate plasminogen binding by PAM nor did additional mutagenesis of Arg101 and His102 and Glu104, which have previously been implicated in plasminogen binding. Plasminogen binding was only abolished with the additional mutagenesis of Arg114 and His115 to alanine. Furthermore, mutagenesis of both arginine (Arg101 and Arg114) and histidine (His102 and His115) residues abolished interaction with plasminogen despite the presence of Lys98 and Lys111 in the binding repeats. This study shows for the first time that residues Arg101, Arg114, His102, and His115 in both the a1 and a2 repeat domains of PAM can mediate high affinity plasminogen binding. These data suggest that highly conserved arginine and histidine residues may compensate for variation elsewhere in the a1 and a2 plasminogen binding repeats, and may explain the maintenance of high affinity plasminogen binding by naturally occurring variants of PAM. [ABSTRACT FROM AUTHOR]

Polymeric particles are a versatile class of local or systemic drug delivery systems, used to improve drugs pharmacokinetics and pharmacodynamics along with patient compliance. Herein, we report a rapid, scalable, and optimized method to encapsulate ciprofloxacin (CPx), a poor water soluble antimicrobial agent, in gelatin microparticles by single step processing via spray-drying of an aqueous solution. The developed particles show mainly a wrinkle morphology with a unimodal distribution, with mean diameters ranging between 2 and 4 μm, depending on the processing conditions. The encapsulation of 1, 2 and 5 wt% CPx narrows the size distribution (1–3 μm). In vitro release experiments showed that up to 80% of encapsulated drug is released during the first 6 h, and the release kinetics was best fitted with the Korsmeyer-Peppas model, explained by the superimposition of drug diffusion and polymer chain relaxation. The minimal inhibitory concentrations against S. aureus and E. coli , obtained from pure and encapsulated ciprofloxacin, demonstrated that the spray-drying process does not inhibit the drug's bioactivity or the process feasibility. Thus, spray-drying of protein-drug particle systems is an advantageous method to produce microparticles with potential to lung delivery systems. [ABSTRACT FROM AUTHOR]

Plasmin(ogen) acquisition is critical for invasive disease initiation by Streptococcus pyogenes (GAS). Host urokinase plasminogen activator (uPA) plays a role in mediating plasminogen activation for GAS dissemination, however the contribution of tissue-type plasminogen activator (tPA) to GAS virulence is unknown. Using novel tPA-deficient ALBPLG1 mice, our study revealed no difference in mouse survival, bacterial dissemination or the pathology of GAS infection in the absence of tPA in AlbPLG1/tPA −/− mice compared to AlbPLG1 mice. This study suggests that tPA has a limited role in this humanized model of GAS infection, further highlighting the importance of its counterpart uPA in GAS disease. [ABSTRACT FROM AUTHOR]