Mechanismy interakce specifické imunity s nádorovými buňkami

Interakce imunitního systému s nádory jsou jedním z nejdůležitějších témat současného imunologického výzkumu. Velké množství nových znalostí recentně prokázalo platnost dávno předpokládaného konceptu imunitního dohledu. Imunitní systém prohledává organismus a deteguje buňky nesoucí nádorové antigeny nebo signály buněčného stresu a ničí je. V tomto procesu hrají dominantí roli T-buňky, NK-buňky a dendritické buňky, cytokinová signalizace a přímá buněčná cytotoxicita. Část vznikajících nádorových buněk ale může těmto mechanismům unikat pomocí klonální selekce. Nakonec tyto nádorové buňky vyvinou i aktivní mechanismy lokálního potlačení imunitní odpovědi. Dochází k infiltraci buněčnými populacemi podporujícími růst nádoru (regulační T-lymfocyty, makrofágy, myeloidní supresivní buňky) a ke vzniku imunosupresivního nádorového mikroprostředí. Nádorové buňky zneužívají k inhibici protinádorové imunity jak rozpustné signální molekuly, tak hlavně povrchové receptory sloužící jako "kontrolní body". V posledních letech bylo schváleno pro klinické použití několik vysoce efektivních terapeutických monoklonálních protilátek blokujících tyto "kontrolní body" a mnoho dalších je testováno v probíhajících klinických studiích. Několik dalších velmi slibných imunoterapeutických přístupů (protinádorové vakcinace,...Interactions between the immune system and tumors have been among the highlights of present immunological research. An extensive body of new knowledge recently substantiated the long-presumed concept of cancer immunosurveillance. Immune system searches the organism for cells expressing tumor antigens or cellular stress signals and destroys them. T-cells, NK-cells and dendritic cells, as well as cytokine signaling and direct cell cytotoxicity play dominant role in this process. However, a fraction of nascent tumors can evade these mechanisms and create a dynamic equilibrium, gradually sculpting its phenotype by clonal selection. Eventually, tumor cells escape immune control by concealing themselves from recognition or by actively subjugating local immune response. This immunosubversion results in formation of immunosuppressive tumor microenvironment by recruiting protumorigenic cell populations, such as Treg cells, macrophages and myeloid derived suppressor cells. Soluble signaling molecules, as well as surface- expressed immune checkpoint molecules are exploited by tumor cells for inhibition of anti-tumor immunity. Highly effective therapeutic antibodies blocking these checkpoints have been developed for clinical use, with many more in current trials. Several other promising immunotherapeutic...Department of Cell BiologyKatedra buněčné biologiePřírodovědecká fakultaFaculty of Scienc

Regulace genové exprese jadernými receptory ve specifickém metabolickém kontextu - evoluční perspektiva

Mezi nejdůležitější regulátory genové exprese u zvířat patří jaderné receptory (NRs) a jejich koregulátory, zejména Mediátorový komplex. Zvláštní zájem vzbuzují NRs zúčastňující se na metabolické a vývojové regulaci a na karcinogenesi: receptory hormonů štítné žlázy (TRs) a retinoidové X receptory (RXRs). Ve své práci se podjímám úkolu objasnit některé aspekty regulace genové exprese těmito NRs: míru evoluční konzervace jejich signalizačních drah; mechanismy negativní regulace jadernými receptory; a možné aplikace těchto objevů v klinické medicíně. Použil jsem bioinformatické a mikroskopické metody, včetně metod genové editace, a to na třech úrovních evoluce zvířat ke studiu vtahu NRs a Mediátoru. Reversní genomická analýza u lidských pacientů trpících syndromem rezistence k thyroidním hormonům je využita k posouzení struktury a funkce subdomén TRβ. Porovnání sekvencí, vázné studie a in vivo experimenty u Trichoplax adhaerens vedly k identifikaci blízkého ortologu lidského RXR na počátku evoluce zvířat. Použitím analýzy databází, editace genomu a mikroskopie jsme identifikovali skutečný ortolog mediátorové podjednotky 28 u Caenorhabditis elegans, což poukazuje na zásadní homologii Mediátorového komplexu mezi nematody a člověkem. Analýza vztahu mezi druhy posiluje koncept konzervace regulační osy...In animals, some of the most critical regulators of gene expression are nuclear hormone receptors (NRs) and their coregulators, specifically the Mediator complex. Of particular interest are the NRs implicated in metabolic and developmental regulation and in carcinogenesis: thyroid hormone receptors (TRs) and retinoid X receptors (RXRs). In this work, I venture to elucidate some aspects of gene expression regulation by these NRs: the degree of evolutionary conservation of signalling based on NRs and their coregulators; the mechanisms of negative regulation by NRs; and possible implications of these findings for clinical medicine. State-of-the-art bioinformatical, genome editing and microscopic techniques are applied at three levels of animal evolution to study NRs and Mediator. Reverse genomics in human patients suffering from the syndrome of resistance to thyroid hormones β are used to infer the structure and function of TRβ subdomains. Alignments, binding studies and in vivo experiments in Trichoplax adhaerens allow identification of a close orthologue of human RXR at the basis of metazoan evolution. Employing database queries, genome editing and microscopy, we describe a correct orthologue of the Mediator subunit 28 in Caenorhabditis elegans, indicating a complete homology of the Mediator complex...BIOCEV, First Faculty of Medicine, Charles UniversityBIOCEV, 1. LF UK1. lékařská fakultaFirst Faculty of Medicin

Gene expression regulation by nuclear receptors in a specific metabolic context - evolutionary perspective

In animals, some of the most critical regulators of gene expression are nuclear hormone receptors (NRs) and their coregulators, specifically the Mediator complex. Of particular interest are the NRs implicated in metabolic and developmental regulation and in carcinogenesis: thyroid hormone receptors (TRs) and retinoid X receptors (RXRs). In this work, I venture to elucidate some aspects of gene expression regulation by these NRs: the degree of evolutionary conservation of signalling based on NRs and their coregulators; the mechanisms of negative regulation by NRs; and possible implications of these findings for clinical medicine. State-of-the-art bioinformatical, genome editing and microscopic techniques are applied at three levels of animal evolution to study NRs and Mediator. Reverse genomics in human patients suffering from the syndrome of resistance to thyroid hormones β are used to infer the structure and function of TRβ subdomains. Alignments, binding studies and in vivo experiments in Trichoplax adhaerens allow identification of a close orthologue of human RXR at the basis of metazoan evolution. Employing database queries, genome editing and microscopy, we describe a correct orthologue of the Mediator subunit 28 in Caenorhabditis elegans, indicating a complete homology of the Mediator complex..

Mechanisms of specific immune response interactions with tumor cells.

Interactions between the immune system and tumors have been among the highlights of present immunological research. An extensive body of new knowledge recently substantiated the long-presumed concept of cancer immunosurveillance. Immune system searches the organism for cells expressing tumor antigens or cellular stress signals and destroys them. T-cells, NK-cells and dendritic cells, as well as cytokine signaling and direct cell cytotoxicity play dominant role in this process. However, a fraction of nascent tumors can evade these mechanisms and create a dynamic equilibrium, gradually sculpting its phenotype by clonal selection. Eventually, tumor cells escape immune control by concealing themselves from recognition or by actively subjugating local immune response. This immunosubversion results in formation of immunosuppressive tumor microenvironment by recruiting protumorigenic cell populations, such as Treg cells, macrophages and myeloid derived suppressor cells. Soluble signaling molecules, as well as surface- expressed immune checkpoint molecules are exploited by tumor cells for inhibition of anti-tumor immunity. Highly effective therapeutic antibodies blocking these checkpoints have been developed for clinical use, with many more in current trials. Several other promising immunotherapeutic..

Trichoplax adhaerens reveals a network of nuclear receptors sensitive to 9-cis-retinoic acid at the base of metazoan evolution

Trichoplax adhaerens, the only known species of Placozoa is likely to be closely related to an early metazoan that preceded branching of Cnidaria and Bilateria. This animal species is surprisingly well adapted to free life in the World Ocean inhabiting tidal costal zones of oceans and seas with warm to moderate temperatures and shallow waters. The genome of T. adhaerens (sp. Grell) includes four nuclear receptors, namely orthologue of RXR (NR2B), HNF4 (NR2A), COUP-TF (NR2F) and ERR (NR3B) that show a high degree of similarity with human orthologues. In the case of RXR, the sequence identity to human RXR alpha reaches 81% in the DNA binding domain and 70% in the ligand binding domain. We show that T. adhaerens RXR (TaRXR) binds 9-cis retinoic acid (9-cis-RA) with high affinity, as well as high specificity and that exposure of T. adhaerens to 9-cis-RA regulates the expression of the putative T. adhaerens orthologue of vertebrate L-malate-NADP+ oxidoreductase (EC 1.1.1.40) which in vertebrates is regulated by a heterodimer of RXR and thyroid hormone receptor. Treatment by 9-cis-RA alters the relative expression profile of T. adhaerens nuclear receptors, suggesting the existence of natural ligands. Keeping with this, algal food composition has a profound effect on T. adhaerens growth and appearance. We show that nanomolar concentrations of 9-cis-RA interfere with T. adhaerens growth response to specific algal food and causes growth arrest. Our results uncover an endocrine-like network of nuclear receptors sensitive to 9-cis-RA in T. adhaerens and support the existence of a ligand-sensitive network of nuclear receptors at the base of metazoan evolution