Peptidoglycan in combination with muramyldipeptide synergistically induces an interleukin-10-dependent T helper 2-dominant immune response

Biomarkers for differentiation of coronavirus disease 2019 or extracorporeal membrane oxygenation related inflammation and bacterial/fungal infections in critically ill patients: A prospective observational study

Secondary infections in coronavirus disease 2019 (COVID-19) patients are difficult to distinguish from inflammation associated with COVID-19 and/or extracorporeal membrane oxygenation (ECMO). Therefore, highly specific and sensitive biomarkers are needed to identify patients in whom antimicrobial therapy can be safely withheld. In this prospective monocentric study, 66 COVID-19 patients admitted to the intensive care unit (ICU) for ECMO evaluation were included. A total of 46 (70%) patients with secondary infections were identified by using broad microbiological and virological panels and standardized diagnostic criteria. Various laboratory parameters including C-reactive protein (CRP), interleukin (IL)-6, procalcitonin (PCT), and IL-10 were determined at time of study inclusion. The best test performance for differentiating bacterial/fungal secondary infections and COVID-19 and/or ECMO associated inflammation was achieved by IL-10 (ROC-AUC 0.84) and a multivariant step-wise regression model including CRP, IL-6, PCT, and IL-10 (ROC-AUC 0.93). Data obtained in the present study highlights the use of IL-10 to differentiate secondary bacterial/fungal infections from COVID-19 and/or ECMO associated inflammation in severely ill COVID-19 patients.

Peptidoglycan-based immunomodulation

Peptidoglycan (PGN) is a unique component in the cytoderm of prokaryotes which can be recognized by different pathogen-associated molecular patterns (PAMPs) in eukaryotes, followed by a cascade of immune responses via different pathways. This review outlined the basic structure of PGN, its immunologic functions. The immunomodulation pathways mediated by PGN were elaborated. PGN induces specific immunity through stimulating different cytokine release and Th1/Th2-dominated immune responses during humoral/cellular immune response. The nonspecific immunity activation by PGN involves immunomodulation by different pattern recognition receptors (PRRs) including PGN recognition proteins (PGRPs), nucleotide oligomerization domain (NOD)-like receptors (NLRs), Toll-like receptors (TLRs), and C-type lectin receptors (CLRs). The sources and classification of PGRPs were summarized. In view of the stimulating activities of PGN and its monomers, the potential application of PGN as vaccine or adjuvant was prospected. This review provides systematic information on PGN functionalities from the point of immunoregulation, which might be useful in the deep exploitation of PGN.Key points. The immunological functions of PGN were illustrated. Cellular and humoral immunomodulation by PGN were outlined. The use of PGN as vaccine or adjuvant was prospected.

Effects of Josamycin on Scratching Behavior in NC/Nga Mice with Atopic Dermatitis-Like Skin Lesions

Our previous study showed that chronic skin colonization by Staphylococcus aureus exacerbated atopic dermatitis (AD) and that control of such skin colonization using antibiotic ointment might relieve AD-related skin inflammation. However, the role of S. aureus colonization in the pruritus accompanying AD was not elucidated. The aim of the present study was to evaluate the effect of topically applied josamycin, a macrolide antibiotic, on the scratching behavior of NC/Nga mice with AD-like skin lesions. Josamycin (0.1%) was topically administered to NC/Nga mice with AD-like skin lesions induced by a mite antigen, Dermatophagoides farinae extract, and the therapeutic effects of josamycin were assessed by measurement of the skin severity score, S. aureus colonization, scratching count, and interleukin (IL)-31 mRNA expression in the skin lesions. Topical treatment with josamycin ointment significantly suppressed the increase of the skin severity score in NC/Nga mice. This suppressive effect was associated with decreases in the S. aureus count on the lesioned skin, scratching behavior of mice and IL-31 mRNA expression in the lesions. The present results show that the severity of AD-like skin inflammation in NC/Nga mice is correlated with the level of S. aureus colonization and subsequent IL-31 production in the skin. Therefore, topical application of josamycin to AD lesions colonized by S. aureus would be beneficial for control of AD by eliminating superficially located S. aureus and by suppressing the IL-31-induced scratching behavior.

OBTAINING AND CHARACTERISTIC OF MUROPEPTIDES OF PROBIOTIC CULTURES CELL WALLS

Розглянуто можливість отримання муропептидів пептидогліканів клітинних стінок Lactobacillus delbrueckii subsp. Bulgaricus B-3964 шляхом комбінації застосування автолітичних процесів та ферментативної обробки біомаси за участю лізоциму та папаїну. Встановлено, що найбільш значні автолітичні зміни біомаси мають місце при застосуванні високотемпературної обробки (90°С протягом 30 хв) на завершальній стадії логарифмічної фази росту бактерій. Так, на восьмій годині інкубації при 37°С вміст амінокислот у культуральному середовищі складає 1,8 мг/см3, а при 90°С – 5,7 мг/см3. Із метою подальшої деструкції автолізату біомаси та отримання низькомолекулярних фрагментів пептидоглікану, досліджували процес його ферментолізу лізоцимом та папаїном окремо та при їхній комбінації. Найвищий вміст НМП у реакційному середовищі мав місце при ферментолізі біомаси Lactobacillus delbrueckii subsp. Bulgaricus B-3964 композицією ферментів при співвідношенні лізоцим:папаїн 1:2. При концентрації ферментів 10 мг/см3 вміст НМП складав 7,2 мг/см3 на 8-му годину інкубації реакційної суміші. Результати досліджень показали, що ефективність ферментолізу автолізату значно вища. Так, кількість НМП у ферментолізаті, який отримали при обробці автолізату композицією лізоцим:папаїн 1:2 при концентрації ферментів 10мг/см3 та тривалості процесу протягом 8 годин на 36% більша, ніж за аналогічних параметрів без застосування процесу автолізу. Методом гель-хроматографії доведено, що у складі ферментолізату присутні фракції білкових сполук з молекулярною масою в межах 70–90 кДа, 30–40 кДа та 294–650 Дa. Молекулярна маса останньої фракції відповідає масі мурамилдипептиду.

Organic components of airborne dust influence the magnitude and kinetics of dendritic cell activation

Bioaerosol exposure in highly contaminated occupational settings is associated with an increased risk of disease. Yet, few determinants allow for accurate prediction of the immunopathogenic potential of complex bioaerosols. Since dendritic cells are instrumental to the initiation of immunopathological reactions, we studied how dendritic cell activation was modified in response to individual agents, combined microbial agents, or air sample eluates from highly contaminated environmental settings. We found that combinations of agents accelerated and enhanced the activation of in vitro-generated murine bone marrow-derived dendritic cell cultures, when compared to individual agents. We also determined that endotoxins are not sufficient to predict the potential of air samples to induce bone marrow-derived dendritic cell activation, especially when endotoxin levels are low. Importantly, bone marrow-derived dendritic cell activation stratified samples from three environmental settings (swine barns, dairy barns, and wastewater treatment plants) according to their air quality status. As a whole, these results support the notion that the interplay between bioaerosol components impacts on their ability to activate dendritic cells and that bone marrow-derived dendritic cell cultures are promising tools to study the immunomodulatory impact of air samples and their components.

OBTAINING AND CHARACTERISTIC OF MUROPEPTIDES OF PROBIOTIC CULTURES CELL WALLS

The possibility of muropeptides obtaining of peptidoglycans of Lactobacillus delbrueckii subsp. Bulgaricus B-3964 cell walls by the combination of the use of autolytic processes and enzyme treatment of biomass with the participation of lysozyme and papain has been considered. It has been established that the most significant autolytic changes in biomass occur in the application of high-temperature processing (90°C for 30 minutes) in the final stage of the logarithmic phase of bacterial growth. Thus, after eighth hour of biomass incubation at 37°C, the amino acid content in the culture medium was 1.8 mg/cm3, and at 90°C it was 5.7 mg/cm3. In order to further destruction of biomass autolysate and obtaining of low molecular weight peptidoglycan fragments, the process of its enzymatic hydrolysis was studied with lysozyme and papain separately and at their combination. The highest content of low molecular weight peptides in the reaction medium occurred at enzymatic hydrolysis of biomass Lactobacillus delbrueckii subsp. Bulgaricus B-3964 by the composition of enzymes at a ratio of lysozyme : papain 1:2. At a concentration of enzymes 10 mg/cm3, the content of low molecular weight peptides was 7.2 mg/cm3 after eighth hour of incubation of the reaction mixture. The results of studies have been shown that the efficiency of enzymatic hydrolysis of autolysates is much higher. Thus, the amount of low molecular weight peptides in the hydrolysate obtained by processing the autolysate with the composition of lysozyme : papain 1:2 at an enzymes concentration 10 mg/cm3 and the duration of the process for 8 hours by 36% higher than for similar hydrolysis parameters without the use of the process of autolysis.The method of gel chromatography was proved that in the hydrolysate there are fractions of protein compounds with a molecular weight in the range of 70–90 kDa, 30–40 kDa and 294–650 Da. The molecular weight of the latter fraction corresponds to the mass of the muramyl dipeptide. The presence of muropeptides was proved by reaction with the Anthron reagent.

Increased Endovascular Staphylococcus aureus Inoculum Is the Link Between Elevated Serum Interleukin 10 Concentrations and Mortality in Patients With Bacteremia

Background

Cell wall peptidoglycan stimulates interleukin 10 (IL-10) production in Staphylococcus aureus bacteremia (SaB) animal models, but clinical data are not available. This study evaluates the impact of intravascular bacterial cell numbers (ie, the level of bacteremia), in patients at the time of clinical presentation on IL-10 production and its association with S. aureus bacteremia (SaB) mortality.

Methods

Blood and isolates were collected in 133 consecutive SaB patients. Serum IL-10 was quantified by an electrochemoluminescence assay. Bacterial inoculum was measured in patient sera with elevated (n = 8) or low (n = 8) IL-10 using a magnetic bacterial capture assay. Staphylococcus aureus from these 2 groups were introduced into whole blood ex vivo to determine IL-10 production with variable inocula.

Results

IL-10 serum concentration was higher in SaB patient mortality (n = 27) vs survival (n = 106) (median, 36.0 pg/mL vs 10.4 pg/mL, respectively, P < .001). Patients with elevated IL-10 more often had endovascular SaB sources. The inoculum level of SaB was higher in patients with elevated serum IL-10 vs patients with low IL-10 (35.5 vs 0.5 median CFU/mL; P = .044). Ex vivo studies showed that 108 CFU/mL yielded greater IL-10 than did 103 CFU/mL (4.4 ± 1.8 vs 1.0 ± 0.6 pg/mL; P < .01).

Conclusions

Elevated IL-10 serum concentrations at clinical presentation of SaB were highly associated with mortality. High intravascular peptidoglycan concentration, driven by a higher level of bacteremia, is a key mediator of IL-10 anti-inflammatory response that portends poor clinical outcome. Using IL-10 as an initial biomarker, clinicians may consider more aggressive antimicrobials for rapid bacterial load reduction in high-risk SaB patients.

Chelate forms of biometalls. Theoretical aspects of obtaining and characteristics

The problem of microelements bioavailability is highlighted and the correct ways of its solution are substantiated as a result of generalization of theoretical aspects of obtaining of the biometals chelate forms. The characteristics of the main biogenic elements, their physiological significance, electrochemical properties are presented. The main examples of the participation of biometals in various biological processes are given. The properties and the structure peculiarities of biometals coordination complexes are considered in detail. It is shown that in obtaining of biometals chelate forms, there is the mutual selectivity and the affinity of biometals and ligands. The main factors of obtaining a hard metal complex are given. Potential bioligands for obtaining bioavailable forms of microelements are detailed. Among them there are amino acids, peptides, proteins, nucleic acids, carbohydrates. The possible character of complexation depending on the nature of the bioligand is indicated. Practical examples of preparation of biometals mixed ligand complexes are given. The expediency of using metabolic products and processing of lactic acid bacteria as promising components of mixed ligand chelate complexes is substantiated. These substances contain in their composition a mass of potential donor atoms that are capable to form covalent and coordination bonds with biomethalles, and also possess high biological and immunotropic activities. The use of this system in the biocoordination compounds of the "metals of life" can provide a synergistic effect of the components, significantly to expand the range of their physiological activity and to increase the degree of assimilation by the body.

Immunological properties of the bacterial origin compounds

It is shown that microorganisms are an integral element of the mаcroorganism immune system.Peptidoglycan, muramyldypeptyd, teichoic acids are structural components of cell walls of microorganisms. These componentsare an object for recognition of the innate immunity system. The necessity of the bacteria cell walls destruction with a view toobtain the immunotropic products for enteral consumption, able to overcome the intestinal barrier, was substantiated.The use of lactic acid bacteria (ICD) for such purposes is perspective and safe, since the considerable experience oftheir cultivation was accumulated, in addition, ICD have got «GRAS» (Generally Recognized As Safe) status. Waste productsof ICD are organic acids, hydrogen peroxide, bacteriocins and others. These substances have got antagonist activity, implicitlyaffect on the immune system, reducing the antigenic load caused by pathogenic microorganisms.A number of physical, chemical and biochemical methods of bacteria cell walls destruction were considered. Thepriority methods is the soft influence, namely the use of specific enzymes or hydrolases, own autolyzins with a combination ofphysical destruction methods.