Biofilm Matrix Exoproteins Induce a Protective Immune Response against Staphylococcus aureus Biofilm Infection

The Staphylococcus aureus biofilm mode of growth is associated with several chronic infections that are very difficult to treat due to the recalcitrant nature of biofilms to clearance by antimicrobials. Accordingly, there is an increasing interest in preventing the formation of S. aureus biofilms and developing efficient antibiofilm vaccines. Given the fact that during a biofilm-associated infection, the first primary interface between the host and the bacteria is the self-produced extracellular matrix, in this study we analyzed the potential of extracellular proteins found in the biofilm matrix to induce a protective immune response against S. aureus infections. By using proteomic approaches, we characterized the exoproteomes of exopolysaccharide-based and protein-based biofilm matrices produced by two clinical S. aureus strains. Remarkably, results showed that independently of the nature of the biofilm matrix, a common core of secreted proteins is contained in both types of exoproteomes. Intradermal administration of an exoproteome extract of an exopolysaccharide-dependent biofilm induced a humoral immune response and elicited the production of interleukin 10 (IL-10) and IL-17 in mice. Antibodies against such an extract promoted opsonophagocytosis and killing of S. aureus. Immunization with the biofilm matrix exoproteome significantly reduced the number of bacterial cells inside a biofilm and on the surrounding tissue, using an in vivo model of mesh-associated biofilm infection. Furthermore, immunized mice also showed limited organ colonization by bacteria released from the matrix at the dispersive stage of the biofilm cycle. Altogether, these data illustrate the potential of biofilm matrix exoproteins as a promising candidate multivalent vaccine against S. aureus biofilm-associated infections.     

Management of unstable angina

One-hundred and seven patients with unstable angina were treated between 1981 and 1987. Platelet dysfunction and elevation of fibrinogen was observed. The efficacy of aspirin, dipyridamole and heparin on coagulation profile is compared. Left main disease was seen in 11.4 per cent. Left anterior descending was occluded in 90.7 per cent. Aortocoronary bypass graft using saphenous vein graft was carried out on all patients. On an average, each patients received 3.5 grafts. Emergency surgery was done in nineteen. Associated ventricular aneurysm was resected in nine. Thirteen patients died. Operative mortality decreased to nil in 1986–1987. Perioperative infarction was seen in five patients. Clinical improvement was seen in 80.3 per cent and 48.9 per cent were asymptomatic. Actuarial survival was 92 per cent after six years. Postoperative coronary angiography in 28 patients showed patency of grafts in 18, partial patency in six and occlusion in four. Aspirin was found useful after surgery to relieve angina. Spiroergometry and Thallium²⁰¹ scintigraphy was useful to assess medical and surgical treatment.     

一氧化氮肝脏保护作用与氧自由基的关系

目的探讨内源性一氧化氮(NO)对大鼠肝缺血再灌注损伤的作用及其与脂质过氧化的关系;方法以缺血再灌注制成大鼠模型,以工具药L-精氨酸(L-arg)为外源性NO的激动剂,观察内源性NO对肝脏损伤程度和脂质过氧化终产物丙二醛(MDA)含量的影响;结果缺血再灌注可造成肝组织损伤,MDA含量增加,内源性NO水平降低,与对照组比较(P＜0.01).以L-arg激动内源性NO,可明显减轻肝组织损伤程度,同时MDA含量降低,NO水平升高,与IR组比较(P＜O.05);结论内源性NO具有肝脏保护作用,其保护机制可能与抗氧自由基有关.     

Biotechnological war against biofilms. Could phages mean the end of device-related infections?

Microorganisms universally attach to surfaces, resulting in biofilm formation. These biofilms entail a serious problem in daily clinical practice because of the great prevalence of implantable device-related infections. Differences in antibiotic activity against planktonic and sessile bacteria may relate to clinical failures in the treatment of biofilm-related infections (BRI). Bacteriophages have several characteristics that make them potentially attractive therapeutic agents in some selected clinical settings, like for example BRI. They are highly specific and very effective in lysing targeted bacteria, moreover, they appear to be safe for humans. Many studies have shown the potential of phages for the treatment of infectious diseases in plants and animals, including infections with highly drug-resistant bacteria. The therapeutic use of bacteriophages, possibly in combination with antibiotics, may be a valuable approach in BRI. However, many important questions still remain that must be addressed before phages can be endorsed for therapeutic use in humans.     

FcRgamma chain does not replace CD3zeta chain in CD3zeta-deficient T lymphocytes of patients with gastric adenocarcinoma

Defective CD3zeta chain expression has been reported in T lymphocytes of patients with inflammatory diseases, such as systemic lupus erythematosus or osteoarthritis, and with cancer. In lupus, the absent CD3zeta chain is replaced by the FcRgamma chain, rendering the T cells hyper responsive. However, there are no data on T lymphocytes from patients with cancer. In this study, the presence of the FcRgamma chain and its associated kinase, Syk, was analysed in patients with gastric adenocarcinoma and healthy subjects. Western blot and immunoprecipitation experiments were carried out with total cell or lipid raft extracts from fresh peripheral blood mononuclear cells or T lymphocytes, and Herpesvirus saimiri-derived T-cell lines (of blood or tissue origin). Our results revealed that the absent CD3zeta chain in cancer T lymphocytes was not replaced by FcRgamma either in fresh T cells or T-cell lines, in contrast to lupus T cells. This altered expression of signalling molecules in T lymphocytes of cancer patients, would explain their low proliferative capacity. Our T-cell lines represent tools to unveil the signalling abnormalities of cancer T lymphocytes.     

Cloning, nucleotide sequencing, and analysis of the AcrAB-TolC efflux pump of Enterobacter cloacae and determination of its involvement in antibiotic resistance in a clinical isolate

Enterobacter cloacae is an emerging clinical pathogen that may be responsible for nosocomial infections. Management of these infections is often difficult, owing to the high frequency of strains that are resistant to disinfectants and antimicrobial agents in the clinical setting. Multidrug efflux pumps, especially those belonging to the resistance-nodulation-division family, play a major role as a mechanism of antimicrobial resistance in gram-negative pathogens. In the present study, we cloned and sequenced the genes encoding an AcrAcB-TolC-like efflux pump from an E. cloacae clinical isolate (isolate EcDC64) showing a broad antibiotic resistance profile. Sequence analysis showed that the acrR, acrA, acrB, and tolC genes encode proteins that display 79.8%, 84%, 88%, and 82% amino acid identities with the respective homologues of Enterobacter aerogenes and are arranged in a similar pattern. Deletion of the acrA gene to yield an AcrA-deficient EcDC64 mutant (EcDeltaacrA) showed the involvement of AcrAB-TolC in multidrug resistance in E. cloacae. However, experiments with an efflux pump inhibitor suggested that additional efflux systems also play a role in antibiotic resistance. Investigation of several unrelated isolates of E. cloacae by PCR analysis revealed that the AcrAB system is apparently ubiquitous in this species.