RNA sequencing is one of the most powerful and novel techniques for transcriptomic studies. However, one of the biggest drawbacks is the high cost associated with such type of high-throughput analysis making this technology unavailable to several laboratories worldwide.
Besides the price, since RNAseq is a relatively new technique, some technical issues have been found and improvements should be done in order to obtain more informative data (such as strand specificity).
Hence, this group of investigators have decided to develop a low-cost library construction protocol that is compatible with the current dominate RNA-seq platform provider, illumina Inc, reducing the expenses in 90% as also the bench time required.
Immunoprophylaxis and immunotherapy are the most desired and promising strategies to avoid biofilm formation on the surface of biotic and abiotic surfaces, and the serious complications related with biofilm detachment, such as pneumonia, endocarditis and sepsis.
Several vaccination studies have been performed using bacterial cell wall proteins as targets, due to their exposure to host immune system components. In this study, 5 S. epidermidis surface protein were selected based on the presence of conserved LPXTG motifs (SesC, SesK, SesB) or ABC transporter lipoproteins (SesL ans SesM), since these motifs and transporters are important for S. epidermidis pathogenesis.
In order to evaluate the immunogenicity of the 5 proteins selected, rabbits were immunized with each of the 5 proteins (recombinant) and with whole bacteria killed by ethanol. The antisera was then collected and tested.
In this paper, the changes in the expression of some of the genes involved in S. epidermidis initial adhesion and biofilm formation on the surface of different biomaterials were analysed.
In order to study the genetic changes over the time, planktonic cells were incubated up to 48h with different biomaterials along with human serum proteins in order to mimic the in vivo environment.
The gene expression profile obtained was very similar in all the biomaterials used. A 10x up-regulation of atlE, gene that encodes the protein AtlE, that is known to be involved in initial adhesion, cell wall metabolism activity and pathogenesis, was detected 48h after contact with the biomaterials surface and human serum proteins.
As I wrote previously, biofilm detachment mechanism is believed to be the origin of severe acute infections such as bacteremia and pneumonia. Therefore, the study of these released cells (either by a passive or an active mechanism), will have an important impact in the seeking for effective prophylactic and/or therapeutic strategies against biofilm-related infections.
In this paper the susceptibility of the S. aureus biofilm-detached cells to oxacillin, a penicillinase-resistant β-lactam antibiotic often used for the treatment of S. aureus infections, was tested.
The way how immune effector cells behave in the presence of a biofilm have been explored in the few years, however, the consequences of these interactions in the immune cells remains largely unknown.
In this work the authors studied the influence of S. epidermidis biofilms in the human mononuclear cells (PMNs) and monocyte-derived macrophages cytokine production profile. Additionaly, the ability of biofilm cells to adhere to human monocyte-derived macrophages and its intracellular survival were also assessed.
It was observed that S. epidermidis biofilm cells (formalin-fixed or alive) induced lower level of pro-inflammatory cytokines production (TNF-alpha, IL12p40, IL-12p70 and IFN-gamma) by the PMNs when compared to the stimulation produced by planktonic cells.
In order to develop an effective vaccine that will help to prevent biofilm formation on the surface of indwelling medical devices, bacterial cell-wall proteins involved in both initial adhesion and accumulation have been extensively studied.
S. epidermidis surface protein C (SesC) seems to be overexpressed in biofilm cells and it was detected in 116 S. epidermidis clinical isolates indicating that it may be essential in the in vivo environment. The role of this protein is still unknown, however, the closest SesC homologue found is the clumping factor A, a fibrinogen-binding protein that recognizes adhesive matrix molecules.
Hence, in this paper the importance of S. epidermidis surface protein C (SesC) in biofilm formation and persistence was evaluated.
Biofilms are known to be less susceptible to antibiotic therapy and also to the host immune system attack. Therefore, in the last few years, the scientific community has focused their studies on the mechanism of biofilm formation and maturation. The interactions and alterations undergone by S. epidermidis when in contact with the host immune system are of utmost importance in the design of new and more effective strategies against biofil-related infections. However, very little is known so far.
In this paper, the authors tried to identify the bacterial surface proteins that undergone expression changes after contact with serum components (in vitro assays), indicating which bacterial cell wall proteins may be involved in the S. epidermidis pathogenesis.
S. epidermidis was then grown in both TSB or TSB supplemented with 70% of rabbit serum in order to mimic the mammalian bloodstream environment. After growing in both conditions, the cell-wall proteins were analysed by 2-dimensional electrophoresis, western blot and mass spectrometry.