IMMUNOLOGICAL MEMORY: THE ROLE OF REGULATORY CELLS (TREGS)

Memory T cells are necessary for development of the immune response and represent one of the most numerous population of human T lymphocytes. On the contrary, suppressive regulatory T cells (Tregs) may terminate the immune response and help to maintain tolerance to self-antigens. These important groups of cells are consisting of different subpopulations and retaining throughout life. However, today there is yet no clear understanding of how the relations between these two groups of cells are formed. In this work we consider possible ways of development and maintenance of CD4+ T cell memory and role of Tregs in these processes. Mechanisms of a differentiation of memory T cells, Tregs and recently described memory Tregs are discussed. The functional and genetic characteristics of these cells are compared. Division of cells according to the functional profile allows drawing parallels between memory T cells and Tregs. These two groups are consisted of central circulating populations (Tc), effector which can migrate toward specific tissues (Te) and tissue-resident cells (Tr), which are staying in peripheral tissues. The similar structural organization of Tregs and memory T cells, existence of transitional forms of tissue-resident Treg subpopulations with properties of memory cells assumes existence of close interrelation between these groups of lymphocytes. The conversion of CD4+ memory T cells into FoxP3-expressing Tregs is one of possible mechanisms of communication between these two groups. The memory Treg-cells with T cell and memory Treg-cell properties can represent a transitional stage of differentiation. On the other side, Treg cells can differentiate independently of memory T cells and accumulate during life in the form of memory Treg cells. The supressor function of Tregs is also necessary as well as function of memory T cells to develop the immune response. It is possible, that a subset of Treg cells undergoes selection in thymus and constitutively express TCR-receptors having affinity with peripheral tissues. Further, these committed cells can be settled into tissues and become tissue-resident Treg cells which maintain regional T cell memory. Tregs can represent the “mirror image” of the structural organization of memory T cells, but with the return sign – the sign of suppression. The quantitative ratio of Tregs and memory T cells (CD4+CD45RO+CD25hiFoxP3+/CD4+CD45RO+CD25-FoxP3-), perhaps, is important criterion for functional assessment of immune system. The balance between these functionally opposite cell subsets has to provide stable functioning of immune system

Analysis of complex singularities in high-Reynolds-number Navier-Stokes solutions

Numerical solutions of the laminar Prandtl boundary-layer and Navier-Stokes equations are considered for the case of the two-dimensional uniform flow past an impulsively-started circular cylinder. We show how Prandtl's solution develops a finite time separation singularity. On the other hand Navier-Stokes solution is characterized by the presence of two kinds of viscous-inviscid interactions that can be detected by the analysis of the enstrophy and of the pressure gradient on the wall. Moreover we apply the complex singularity tracking method to Prandtl and Navier-Stokes solutions and analyze the previous interactions from a different perspective

Tumor microenvironment: the formation of the immune profile

Tumor microenvironment (TME) is formed as a result of interaction and cross-linking between the tumor cell and different types of surrounding cells. Recent studies have shown that the tumor reprograms the microenvironment so that TME promotes the development of primary tumors, their metastasis and becomes an important regulator of oncogenesis. Under the influence of the tumor, the immune profile in the TME undergoes significant changes, “editing". An immunosuppressive network is formed, which suppresses the activity of the main effector of cellular immunity — T lymphocytes. T cells in TMA are in a state of anergy and exhaustion. T cells in TME are characterized by increased expression of inhibitory receptors, decreased secretion of cytokines and cytolytic activity. Blocking inhibitory receptors with specific antibodies can lead to the restoration of the functions of exausted T cells. Therefore, the restoration of the functional activity of T lymphocytes is one of the important strategies in cancer immunotherapy. The formation of the immune profile is influenced by genetic aberrations accumulating in the tumor. They play an important role in creating a specific, characteristic only for this tumor immune environment in the TME. Genetic changes in tumor cells lead to phenotypic and functional rearrangements of lymphocytes, which allows the tumor to escape the reaction of immune cells. Since many tumors occur after prolonged inflammation or exhibit characteristics of chronic inflammation as they progress, inflammation is considered an important factor in the formation of immune profile in TME. Immune infiltrates from different human tumors associated with inflammation may contain valuable prognostic and pathophysiological information. Macrophages in the TME now began to be regarded as descriptive marker and as a therapeutic target. One of the main mechanisms by which tumor cells reprogram surrounding cells is the release of exosomes — small vesicles that carry and deliver proteins and nucleic acids to other cells. When exosomal cargo is absorbed, molecular, transcriptional and translational changes occur in the recipient non-tumor cells in the TME. Therefore, tumor exosomes are an effective means by which the functions of immune cells in TME are purposefully changed. Thus, along with individual molecular and genomic testing of the tumor, attention should be paid to a deeper analysis of the immune profile of TME. It is a large resource of biomarkers and targets for immunotherapy

The method of surgical access while treatment of nonclostridial anaerobic infections of soft tissues of tongue and oral cavity floor

The author analyzed the methods of operational interventions in the area of soft tissues of oral cavity floor and tongue while treatment of nonclostridial anaerobic infections. Twenty-nine of the forty-two analyzed patients were operated, using the authors’ method of T-shaped incision. The number of lethal outcomes has decreased almost twice. Treatment results allow us to recommend the proposed method for wider use in clinical practic

A novel method of modifying immune responses by vaccination with lipiodol-siRNA mixtures

The dendritic cell (DC) possesses the ability to stimulate both T helper 1 (Th1) and Th2 responses depending on activation stimuli. Although it is known that chemically or genetically modified DC can be used therapeutically to steer immune responses towards either Th1 or Th2, cellular therapy with ex vivo manipulated DC is clinically difficult. Here we demonstrate a novel method of switching immune responses from Th1 to Th2 through in vivo immune modulation by administration of siRNA. We demonstrate that siRNA targeting of the IL-12p35 gene leads to a Th2 bias in vitro through an IL-10 dependent mechanism. In vivo administration of siRNA admixed with the oil-based contrast agent lipiodol in the presence of antigen and adjuvant induced a deviation in recall response to reduced production of IFN-γ and augmented IL-4 response using either KLH or ovalbumin. This simple method of in vivo modification of immune response possesses therapeutic potential in Th1-mediated diseases such as multiple sclerosis and autoimmune diabetes

Macrophage polarization in sarcoidosis

Sarcoidosis is a systemic inflammatory disease of unknown etiology, characterized by the formation of epithelioid cell granulomas, multisystem lesions with a certain frequency of involvement of various organs, mainly the lungs (up to 90% of cases). Over the past decade, significant progress has been made in understanding the pathogenesis of sarcoidosis, the important role of immunological, genetic and environmental factors in the development of this pathology has been established. It is believed that the leading mechanism in the pathogenesis of sarcoidosis is the aberrant activation of the innate and adaptive immune response to unidentified antigen(s), which leads to the development of granulomatous inflammation and the formation of granulomas. However, despite the huge number of studies that has been carried out, the mechanisms and signaling pathways that control the development of the inflammatory process during the formation of granulomas and the progression of pathology have not been fully determined.This literature review examines the important role of various cytokines and T helper subpopulations in sarcoidosis. Particular attention is paid to the cells of innate immunity – macrophages in the pathogenesis of this disease. These cells play a key role in the formation of sarcoid granulomas and in the pathogenesis of sarcoidosis. The macrophage population is characterized by plasticity and functional heterogeneity. In response to various signals from the microenvironment, macrophages are able to acquire certain phenotypes. The review considers the issues of polarization of macrophages, changes in the phenotype of these cells to subpopulations M1 (M1 phenotype; classically activated; pro-inflammatory) and M2 (M2 phenotype; alternatively activated, anti-inflammatory). These two cell populations are characterized by the expression of different markers on their surface, which allow these cells to differentiate from each other. The analysis of literature data on the levels of key polarizing cytokines for macrophages and cells-producers of these cytokines that patients with sarcoidosis have, in acute and chronic course of the disease, was carried out.Important aspects of the alternative activation of macrophages of the M2 phenotype and their division into subtypes: M2a, M2b, M2c, M2d are noted. The features of various subtypes’ activation of macrophages in this granulomatosis and their importance in the development and progression of pathology are considered. Studying the role of macrophages’ phenotypes, understanding the mechanisms by which the phenotypes of these cells are activated and modulated in various microenvironmental conditions, can contribute to the development and implementation into clinical practice of new therapeutic approaches for the treatment of sarcoidosis and many other forms of pathologies

Permeability hysteresis in gravity counterflow segregation

Hysteresis effects in two-phase flow in porous media are important in applications such as waterflooding or gas storage in sand aquifers. In this paper, we develop a numerical scheme for such a flow where the permeability hysteresis is modeled by a family of reversible scanning curves enclosed by irreversible imbibition and drainage permeability curves. The scheme is based on associated local Riemann solutions and can be viewed as a modification of the classical Godunov method. The Riemann solutions necessary for the scheme are presented, as well as the criteria that guarantee the well-posedness ofthe Riemann problem with respect to perturbations of left and right states. The numerical and analytical results show strong influence of the permeability hysteresis on the flow. In addition, the numerical scheme accurately reproduces the available experimental data once hysteresis is taken into account in the model.Shaerer, C., Sarkis, M., Marchesin, D. and Bedrikovetski, P

A new kind of Lax-Oleinik type operator with parameters for time-periodic positive definite Lagrangian systems

In this paper we introduce a new kind of Lax-Oleinik type operator with parameters associated with positive definite Lagrangian systems for both the time-periodic case and the time-independent case. On one hand, the new family of Lax-Oleinik type operators with an arbitrary $u\in C(M,\mathbb{R}^1)$ as initial condition converges to a backward weak KAM solution in the time-periodic case, while it was shown by Fathi and Mather that there is no such convergence of the Lax-Oleinik semigroup. On the other hand, the new family of Lax-Oleinik type operators with an arbitrary $u\in C(M,\mathbb{R}^1)$ as initial condition converges to a backward weak KAM solution faster than the Lax-Oleinik semigroup in the time-independent case.Comment: We give a new definition of Lax-Oleinik type operator; add some reference

ECFA Detector R&D Panel, Review Report

Two special calorimeters are foreseen for the instrumentation of the very forward region of an ILC or CLIC detector; a luminometer (LumiCal) designed to measure the rate of low angle Bhabha scattering events with a precision better than 10$^{-3}$ at the ILC and 10$^{-2}$ at CLIC, and a low polar-angle calorimeter (BeamCal). The latter will be hit by a large amount of beamstrahlung remnants. The intensity and the spatial shape of these depositions will provide a fast luminosity estimate, as well as determination of beam parameters. The sensors of this calorimeter must be radiation-hard. Both devices will improve the e.m. hermeticity of the detector in the search for new particles. Finely segmented and very compact electromagnetic calorimeters will match these requirements. Due to the high occupancy, fast front-end electronics will be needed. Monte Carlo studies were performed to investigate the impact of beam-beam interactions and physics background processes on the luminosity measurement, and of beamstrahlung on the performance of BeamCal, as well as to optimise the design of both calorimeters. Dedicated sensors, front-end and ADC ASICs have been designed for the ILC and prototypes are available. Prototypes of sensor planes fully assembled with readout electronics have been studied in electron beams.Comment: 61 pages, 51 figure