Increase of CD4+CD25highFoxP3+ cells impairs in vitro human microbicidal activity against Mycobacterium tuberculosis during latent and acute pulmonary tuberculosis

Background Regulatory T cells (Tregs) play a critical role during Mycobacterium tuberculosis (Mtb) infection, modulating host responses while neutralizing excessive inflammation. However, their impact on regulating host protective immunity is not completely understood. Here, we demonstrate that Treg cells abrogate the in vitro microbicidal activity against Mtb. Methods We evaluated the in vitro microbicidal activity of peripheral blood mononuclear cells (PBMCs) from patients with active tuberculosis (TB), individuals with latent tuberculosis infection (LTBI, TST+/IGRA+) and healthy control (HC, TST-/IGRA-) volunteers. PBMCs, depleted or not of CD4+CD25+ T-cells, were analyzed to determine frequency and influence on microbicidal activity during in vitro Mtb infection with four clinical isolates (S1, S5, R3, and R6) and one reference strain (H37Rv). Results The frequency of CD4+CD25highFoxP3+ cells were significantly higher in Mtb infected whole blood cultures from both TB patients and LTBI individuals when compared to HC. Data from CD4+CD25+ T-cells depletion demonstrate that increase of CD4+CD25highFoxP3+ is associated with an impairment of Th-1 responses and a diminished in vitro microbicidal activity of LTBI and TB groups. Conclusions Tregs restrict host anti-mycobacterial immunity during active disease and latent infection and thereby may contribute to both disease progression and pathogen persistence.

Effects of Cytokines IFN-γ and TGF-β on the Functional Activity of Blood Mononuclear Cells against Giardia lamblia

Background: This study aimed to analyze cultures of mononuclear (MN) cells with Giardia lamblia to determine the levels of the cytokines IFN-γ and TGF-β and the functional activity of MN cells after incubation with cytokines. Methods: This study was conducted in 2018 in Barra do Garças, Mato Grosso State, Brazil. Blood samples were collected from 60 healthy volunteer donors to obtain leukocytes. The levels of IFN-γ and TGF-β were quantified in trophozoite cell culture supernatants. Superoxide release, phagocytosis, microbicidal activity, apoptosis and intracellular calcium release were analyzed. Results: The cytokines evaluated were detected in the culture supernatant of MN cells and G. lamblia. Regardless of the type of cytokine, MN cells increased superoxide release in the presence of G. lamblia. Phagocytosis, microbicidal activity and apoptosis were higher when MN phagocytes were treated with cytokines. The highest microbicidal activity and apoptosis rates were observed in MN cells cultured with TGF-β. IFN-γ increased the release of intracellular calcium by MN phagocytes. Conclusion: Cytokines play a beneficial role in the host by activating MN cells against G. lamblia. In addition, phagocytosis causes G. lamblia death and that the modulation of the functional activity of blood MN phagocytes by cytokines is an alternative mechanism for eliminating G. lamblia.

DIFFERENTIATED TRANSFORMATION OF THE PHENOTYPE OF SUBPOPULATIONS OF NEUTROPHILIC GRANULOCYTES IN VIRAL-VIRAL AND PURULENT BACTERIAL INFECTIONS IN IMMUNOCOMPROMETED CHILDREN

Children with clinical signs of immunocompromise have impaired functioning of the immune system. At the same time, the state of subpopulations of multifunctional neutrophil granulocytes (NG), which provide antiviral and antibacterial protection, in such patients has been poorly studied. Objective of the study: to assess the features of the transformation of the phenotype of the three most significant subpopulations of NG, their association with impaired phagocytic and microbicidal activity in immunocompromised children with atypical viral-viral co-infections and bacterial infections, and to clarify their differential diagnostic significance. Materials and methods of research: the phenotypes of NG subpopulations expressing CD64, CD32, CD16, CD11b receptors, phagocytic and microbicidal activity of NG were studied in the peripheral blood of 43 immunocompromised children of both sexes aged of 5–9 years old suffering from recurrent ARVI, atypical chronic mono – or mixed herpes virus infections (HVI) and purulent bacterial infection. 3 study groups were formed: 1st – repeated ARVI/HVI mono, 2nd – repeated ARVI/HVI mixed, 3rd – minor purulent infection (MPI) and a comparison group (20 apparently healthy children). Results: different differentiated transformation of the phenotype of functionally significant subpopulations of NG associated with impaired functional activity of NG as well as with the incidence of viral co-infections (repeated ARVI and recurrent HVI mixed) and the severity of clinical manifestations of MPI has been identified in the studied groups. Conclusion. Еvaluation of the features of transformation of phenotype of NG subpopulations, their effector functions in immunocompromised children with atypical viral-viral co-infections and purulent bacterial infections, will allow in the future to optimize the methods of target immunotherapy aimed at remodulating the negatively transformed phenotype of NG subpopulations, correcting their dysfunctions and, thereby, significantly increase the clinical effectiveness of therapeutic and preventive measures.

Regulatory cytokine effects in vitro on the phenotype of subpopulations CD62L+CD63-, CD62L+CD63+ and microbicidal activity of neutrophilic granulocytes in patients with colorectal cancer

Relevance. Neutrophilic granulocytes (NG) are the first cells of the immune system to migrate to the tumor and are actively involved in the implementation of a full-fledged antitumor response through the mechanisms of direct killing of tumor cells, extracellular lysis (NET), and through the activation of antibody-dependent cellular cytotoxicity (ADCC), inhibition of angiogenesis, initiation of other cells with antitumor activity. The aim of the study was to study the effect of cytokines IFN, IFN, G-CSF on the CD62L+CD63- and CD62L+CD63+ subsets and the microbicidal activity of NGs in patients with colorectal cancer (CRC) in vitro. Materials and methods. We studied samples of peripheral blood (PB) of 10 patients of both sexes 38-70 years old with newly diagnosed untreated CRC stage II-III (study group) and 10 healthy volunteers (comparison group). The subsets CD62L+CD63+ NG, CD62L+CD63- NG were assessed by flow cytometry (CYTOMICS FC500, Beckman Coulter, USA), the microbicidal functions of NG were tested by cytochemical methods: activity of NADPH - oxidases, myeloperoxidase (MP), level of cationic protein (CP) in spontaneous tests and under additional stress of S. aureus . The effect of IFN, IFN, G-CSF cytokines on subsets and the microbicidal activity of NG in vitro was studied in both study groups. Microsoft Exel 2016 and StatPlus 2010 were used for statistical processing of the obtained data using nonparametric tests: Me (Q1; Q3), Mann-Whitney U-test and Wilcoxon test . Results . The features of transformation of CD62L+ CD63-NG and CD62L+ CD63+ NG subsets of PB in CRC have been established, that allows to get an idea of the NG ability to roll and readiness to activate the microbicidal arsenal, various defects of spontaneous and induced microbicidal activity of oxygendependent and oxygen-independent mechanisms of NG. The effects of cytokine influence on NG in CRC in vitro have been shown, which indicates the possibility of regulating the receptor and microbicidal functions of NG, and, on the other hand, suggests defects in NG perception of regulatory stimuli, that is confirmed by the progression of tumor growth.