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Pseudomonas aeruginosa is a ubiquitous environmental organism and an opportunistic pathogen that causes chronic lung infections in the airways of cystic fibrosis (CF) patients as well as other immune-compromised individuals. During infection, P. aeruginosa enters the terminal bronchioles and alveoli and comes into contact with alveolar lining fluid (ALF), which contains homeostatic and antimicrobial hydrolytic activities, termed hydrolases. These hydrolases the potential to modify lipids, carbohydrates and proteins on the surface of invading microbes. Here we show that hydrolase levels between human ALF from healthy and CF patients differ. CF-ALF influences the P.
aeruginosa cell wall by reducing the content of one of its major polysaccharides, Psl. This CF-ALF induced Psl reduction does not alter initial bacterial attachment to surfaces drives the activation of neutrophils and triggers their oxidative response; thus, defining human CF-ALF as a new innate defense mechanism to control P. aeruginosa infection, but at the same time potentially adding to the chronic inflammatory state of the lung in CF patients. Conflict of interest statement: The authors declare that they have no competing Peptidylarginine Deiminase of Porphyromonas gingivalis Modulates the Interactions between Candida albicans Biofilm and Human Plasminogen and Microorganisms that create mixed-species biofilms in the human oral cavity include, among others, the opportunistic fungus Candida albicans and the key bacterial pathogen in periodontitis, Porphyromonas gingivalis. Both species use arsenals of virulence factors to invade the host organism and evade its immune system including peptidylarginine deiminase that citrullinates microbial and host proteins, altering their function. We assessed the effects of this modification on the interactions between the C. albicans cell surface and human plasminogen and kininogen, key components of plasma proteolytic cascades related to the maintenance of hemostasis and innate immunity.
Mass spectrometry was used to identify protein citrullination, and microplate tests to quantify the binding of modified plasminogen and kininogen to C. albicans cells. Competitive radioreceptor assays tested the affinity of citrullinated kinins to their specific cellular receptors. The citrullination of surface-exposed fungal proteins reduced the level of unmodified plasminogen binding but did not affect unmodified kininogen binding. However, the modification of human proteins did not disrupt their adsorption to the unmodified fungal cells. In contrast, the citrullination of kinins exerted a significant impact on their interactions with cellular receptors reducing their affinity and thus affecting the role of kinin peptides in the development of inflammation. Buy now of interest statement: The authors declare no conflicts of interest in Bacterial infection of biomaterials.
Experimental protocol for in vitro adhesion Some of the more common reactor systems and novel diagnostic tools employed in the study of bacterial cell adhesion and biofilm formation have been described. Sampling and experimental requirements are shown to greatly influence the design and construction of a biofilm reactor. As analytical techniques evolve, the capability to non-invasively follow the development of biofilms and to assess the attached cell reactivity has increased. Both non-invasive and invasive diagnostic methods affect the type and design of biofilm flow reactor with both types of analyses providing complementary information on biofilm processes. To correctly interpret the contribution of a specific rate process to the net accumulation of cells at a substratum, one requires a reactor system devoid of any mass transfer limitations and a process analysis approach to allow for the correct collection and analysis of data. Quorum sensing and biofilms in the pathogen, Streptococcus pneumoniae. Bacteria are able to colonize and thrive in a variety of different environments as a biofilm, but only within the last half century new insights have been gained in this complex biosystem.
Bacterial biofilms play a major role in human health by forming a defensive barrier against antibacterial chemical therapeutics and other potential pathogens, and in infectious disease when the bacteria invade normally sterile compartments. Quorum sensing is the signaling network for cell-to-cell communication and utilized by bacteria to regulate biofilms and other cellular processes. This review will describe recent advances in quorum sensing and biofilms. Initially, it will focus on Streptococcus pneumoniae biofilm regulation and the involvement of the ComABCDE pathway.
