Neutrophil extracellular traps: mechanisms of formation and role in health and disease.

Recent insights into the specific type of cell death characteristic of neutrophils, called NETosis, are summarized. NETosis is a process of generation of Neutrophil Extracellular Traps (NETs), whose main components are DNA, granular antimicrobial peptides, and nuclear and cytoplasmic proteins. The structure of NETs determines their bactericidal, fungicidal, antiprotozoal, and antiviral properties. Therefore, NETs production by neutrophils is an essential immune response to infection. In addition to the antimicrobial function, NETosis is involved in many inflammatory and autoimmune disorders and participates in the regulation of noninfectious processes. The molecular mechanisms of NET formation, bactericidal effect, and involvement in some noninfectious, autoimmune, and inflammatory processes are discussed in detail in this review.

[Induction and protective properties of antibodies against muramyl peptides of gram-negative bacteria].

AIM: Characterize the role of humoral immune response in mechanisms of action of muramyl dipeptide immune stimulators. MATERIALS AND METHODS: Mice were immunized by a complex of muramyl peptides (CMP) obtained from Salmonella typhi peptidoglycan and consisting of 3 components: 1) N-acetyl-D-glucoasminyl-(beta1- > 4)-N-acetyl-D-muramoyl-L-alanyl-D-isoglutaminyl-meso-diaminopimelic acid (GMtri); 2) N-acetyl-D-glucosaminyl-(beta1- > 4)-N-acetyl-D-muramoyl-L-alanyl-D-isoglutaminyl-meso-diaminopimeloyl-D-alanine (GMtetra) and 3) GMtetra dimer (diGMtetra), in which monomeric residues of GMtetra are linked by an amid bond between carboxyl group of terminal D-alanine of one of GMtetra residues and omega-amino group of meso-diaminopimelic acid of the other GMtetra residue. RESULTS: Immunization resulted in a multifold increase of IgM, IgG1 and IgG2a titers against CMP. Antibodies were directed against the whole molecule of diGMtetra and did not recognize its fragments. Sera of mice immunized with CMP protected the mice from lethal infection with Gram-negative (S. typhimurium) but not Gram-positive (Staphylococcus aureus) microorganisms. CONCLUSION: Induction of protective antibodies may present a novel mechanism of action of muramyl dipeptide immune stimulators.

[Prediction of remote results after surgical management of patients presenting with atherosclerosis obliterans of the lower-limb arteries].

Forecasting the development of implants' narrowing appears to be one of the most important problems encountered in vascular surgery today. The present study was therefore undertaken to work out a comprehensive diagnostic methodology making it possible to reliably predict the development of stenosis of vascular anastomoses during the postoperative period in patients presenting with atherosclerosis obliterans. The work was based upon the findings obtained by examining a total of seventy-nine patients diagnosed with atherosclerosis obliterans of the lower-limbs arteries, also including assessment of a large number of haemodynamic and immunological parameters both before and after reconstructive vascular interventions. The study showed substantial dynamics of a series of immunological and haemodynamic indices on the background of the operation and during the postoperative period. Based on the mathematical processing of the obtained data, the authors managed to reveal the factors playing a leading role in the development of stenosis, having also worked out a prognostic algorithm making it possible with high reliability to predict the development of stenosis of arterial anastomoses.

[Changes in functional activity of macrophages caused by bacterial muramylpeptides].

Muramylpeptides from bacteria cell wall are strong stimulators of immune system and phagocytic cells are main effectors. Dimer containing glucoseaminylmuramylpentapeptide (di-GMPP) was obtained from cell wall of Salmonella typhi bacteria. Di-GMPP decrease the phagocytic activity of macrophages obtained from peripheral blood of healthy donors and increase intracellular killing. Also di-GMPP resulted in decrease of expression of macrophages' receptors which play role in phagocytosis (CD16, CD64, CD11b) and detection of bacterial molecular patterns (TLR2, TLR4, CD206), as well as in increase of expression of antigen-presenting (HLA-DR) and costimulatory molecules (CD86, CD40) which involved in formation of immunological synapse and presentation of antigens to T- and B-lymphocytes.

[Assessment of bactericidal and growth-inhibiting activity of blood serum using flow cytometry and photometry].

Method of measurement of biological fluids bactericidal activity against Staphylococcus aureus using laser flow cytometry has been developed and proposed for clinical use. Overall bactericidal activity of sera of healthy donors has been assessed by this method. Strong positive correlation between bactericidal activity measured by flow cytometry and ability of the sera of healthy donors to inhibit bacterial growth assessed by photometric method was determined. High degree of positive correlation between results of cytometry and classical microbiological method of measurement of mentioned parameters has been shown.

Immunomodulatory properties of Cumaside.

The medical lead, so-called Cumaside, was created on the basis of triterpene oligoglycosides from the Far-Eastern edible sea cucumber (holothurian) Cucumaria japonica and its immunomodulatory properties were studied. The haemolytic activity of Cumaside was significantly reduced in comparison with original glycosides due to the glycoside-cholesterol complex formation. The influence of Cumaside on mouse macrophages in low doses was accompanied by more then two-fold stimulation of lysosomal activity. This preparation was found to increase significantly the animal resistance against bacterial infections elicited by various pathogens. It stimulated phagocytosis, ROS formation, IL6 and TNF-alpha production in lymphocytes, increased the number of antibody producing cells and amplified the expression of several cell surface molecules (CD3, CD4, CD8) preliminary cultured with hydrocortisone. At the same time the preparation did not affect the delayed-type hypersensitivity, proliferative activity of lymphocytes, cytotoxic activity of NK-cells and cytokine IFNgamma and IL12p70 release. The mechanism of Cumaside action is discussed.

[Evaluation of serum bactericidal activity by laser flow cytofluorometry].

A method for evaluation of serum bactericidal activity against S. aureus by laser flow cytofluorometry has been developed and proposed for clinical application. This method was used to study the overall bactericidal activity of donors' sera and to estimate the contribution of complement to the process of bacteriolysis.

[Multiple cerebral abscess caused by Nocardia brasilientis].

Streptococcus aureus, streptococci, and enterobacteria were major causative agents of abscesses of the brain. At present, associated infection is responsible for 60% of cerebral abscesses. When systemic and specific immunities are diminished, a risk for cerebral abscesses caused by fungi increases. Among them, there are the most common fungi Candida species or Aspergillus species. The paper gives an example of successful complex treatment of multiple cerebral abscesses caused by an association of Nocardia brasiliensis and Staphylococcus epidermidis. The specific feature of the observation was the correct diagnosis before intraoperative verification of cerebral abscesses. The disease developed in the presence of diminished systemic immunity and in the absence of specific immunity to Nocardia. Immunodeficiency could be caused by prior herpetic infection, Epstein-Barr disease, a wasp bite. The pathogen that was able to cause microstrokes played an indubitable role in the pathogenesis of the disease, which predisposed to the development of cerebral abscesses in patients with immunodeficiency. Impaired blood circulation in the occipital region could be also induced by wasp venom.

Peripheral blood leukocytes from multiple sclerosis patients are coated with factors inhibiting their chemotaxis in the presence of myelin basic protein.

In this study myelin basic protein (MBP) was tested for its effect on chemotaxis of human peripheral blood leukocytes (PBL) and neutrophils from multiple sclerosis (MS) patients. MBP appeared to inhibit specifically the formyl-methionyl-leucyl-phenylalanine (FMLP)-induced chemotaxis of both the total leukocyte population and neutrophils. In comparison, no inhibition of chemotaxis was observed in healthy donors and patients with other neurological diseases. From MS patients we collected neutrophil supernatants obtained by incubation of the cells in a serum-free medium at 37 degrees C for 60 min and evaluated their effect on chemotaxis of neutrophils from healthy donors. Chemotaxis of healthy donor neutrophils was inhibited specifically in the presence of MBP after treatment with these supernatants, presumably relating to the presence of immune complexes on the surface of neutrophils from MS patients. Those complexes can be eluted into the incubation medium and coat healthy donor neutrophils, thus arming them specifically.

Peripheral blood neutrophils from HIV-1-infected individuals are armed with factors that cause inhibition of their migration in response to specific antigens.

In this study, synthetic peptides that copy conserved regions of the HIV-1 envelope proteins gp120 and gp41 were tested for their impact on the chemotaxis of leukocytes and neutrophils from HIV-1-infected individuals, while neutrophils from HIV-1-infected patients were tested for their effect on the chemotaxis of neutrophils from healthy donors. The synthetic peptides (corresponding to the 251-272-amino acid sequence of gp120 and the 584-618-amino acid sequence of gp41) were capable of specifically inhibiting the formyl peptide-induced chemotaxis of cells from HIV-1-infected patients, and such inhibition was observed both with a total leukocyte population and with pure neutrophils. The migration of neutrophils from healthy donors was specifically inhibited in the presence of either of the synthetic peptides of HIV-1 envelope proteins after their incubation with neutrophil supernatants obtained from HIV-1-infected individuals. As shown by ELISA tests, the neutrophil supernatants from HIV-1-infected individuals contain antibodies to a recombinant env-1 protein that might be one of the reasons for the specific arming of neutrophils from HIV-1-infected persons.