Autophagy Induced by Toll-like Receptor Ligands Regulates Antigen Extraction and Presentation by B Cells.

The engagement of B cells with surface-tethered antigens triggers the formation of an immune synapse (IS), where the local secretion of lysosomes can facilitate antigen uptake. Lysosomes intersect with other intracellular processes, such as Toll-like Receptor (TLR) signaling and autophagy coordinating immune responses. However, the crosstalk between these processes and antigen presentation remains unclear. Here, we show that TLR stimulation induces autophagy in B cells and decreases their capacity to extract and present immobilized antigens. We reveal that TLR stimulation restricts lysosome repositioning to the IS by triggering autophagy-dependent degradation of GEF-H1, a Rho GTP exchange factor required for stable lysosome recruitment at the synaptic membrane. GEF-H1 degradation is not observed in B cells that lack αV integrins and are deficient in TLR-induced autophagy. Accordingly, these cells show efficient antigen extraction in the presence of TLR stimulation, confirming the role of TLR-induced autophagy in limiting antigen extraction. Overall, our results suggest that resources associated with autophagy regulate TLR and BCR-dependent functions, which can finetune antigen uptake by B cells. This work helps to understand the mechanisms by which B cells are activated by surface-tethered antigens in contexts of subjacent inflammation before antigen recognition, such as sepsis.

Detection of Sepsis in Platelets Using MicroRNAs and Membrane Antigens.

The present study proposes to legitimize in sepsis a characteristic found in platelets that suffer storage lesions in blood banks, which is the increased expression of miRNA miR-320a in relation to miR-127. Under physiologically normal conditions, an inverse relationship is observed. The aim of this study was to verify whether the analysis of miR-320a and miR-127 expression in platelets could detect a decrease in their viability and function due to the presence of pathogens in the blood of patients hospitalized in the Intensive Care Unit. We also investigated the expression of membrane antigens sensitive to platelet activation. Of the 200 patients analyzed, only those who developed sepsis (140) were found to have a higher relative quantity of miR-320a than that of miR-127. This characteristic and the increased expression of membrane antigens P2Y12, CD62P, CD41, and CD61 showed a significant association (p < 0.01) with all types of sepsis evaluated in this study. Additionally, 40% of patients hospitalized for sepsis had negative results for the first cultures. We conclude that analysis of miR-127 and miR-320a expression combined with membrane antigens evaluation, in association with the available clinical and diagnostic parameters, are important tools to detect the onset of sepsis.

MERTK on mononuclear phagocytes regulates T cell antigen recognition at autoimmune and tumor sites.

Understanding mechanisms of immune regulation is key to developing immunotherapies for autoimmunity and cancer. We examined the role of mononuclear phagocytes during peripheral T cell regulation in type 1 diabetes and melanoma. MERTK expression and activity in mononuclear phagocytes in the pancreatic islets promoted islet T cell regulation, resulting in reduced sensitivity of T cell scanning for cognate antigen in prediabetic islets. MERTK-dependent regulation led to reduced T cell activation and effector function at the disease site in islets and prevented rapid progression of type 1 diabetes. In human islets, MERTK-expressing cells were increased in remaining insulin-containing islets of type 1 diabetic patients, suggesting that MERTK protects islets from autoimmune destruction. MERTK also regulated T cell arrest in melanoma tumors. These data indicate that MERTK signaling in mononuclear phagocytes drives T cell regulation at inflammatory disease sites in peripheral tissues through a mechanism that reduces the sensitivity of scanning for antigen leading to reduced responsiveness to antigen.

Expansion of T regulatory lymphocytes by murine bone marrow dendritic cells previously stimulated with Anisakis simplex larval antigens.

BACKGROUND: Anisakis simplex antigens present immunomodulatory properties by the induction of tolerogenic dendritic cells (DCs) in mice. OBJECTIVES: To study the capacity of DCs stimulated with A. simplex excretory-secretory (ES) or crude extract (CE) to generate Tregs. To investigate in vitro effects of antigens on the metabolic activity of splenocytes induced by LPS or CpG. METHODS: Phenotypic and functional characterization of T cells co-cultured with A. simplex-pulsed DCs was performed by flow cytometry. Lymphocyte mitochondrial respiratory activity was estimated by the Alamar Blue® Assay. FINDINGS: In C57BL/6J, CD4+CD25-Foxp3+ and CD8+CD25-Foxp3+ populations increased by CE-stimulated-DCs. In BALB/c, CE-stimulated-DCs caused the expansion of CD4+CD25+Foxp3+IL-10+ and CD8+CD25+Foxp3+IL-10+. IFN-γ expression raised in BALB/c CD4+CD25+ and CD4+CD25- for CE and ES, respectively. ES-stimulated-DCs increased CD4+CD25+ Foxp3+ and CD8+CD25- Foxp3+ expression in T cells. The association of ES or CE with LPS produced the increase in splenocyte activity in C57BL/6J. The association of CE with CpG decreased the proliferation caused by CpG in C57BL/6J. MAIN CONCLUSIONS: A. simplex increase the frequency of Tregs, which in turn produce IL-10 and IFN-γ. The host genetic base is essential in the development of anti-Anisakis immune responses (Th2, Th1, Treg).

The IL-33/ST2 pathway is not essential to Th2 stimulation but is key for modulation and survival during chronic infection with Schistosoma mansoni in mice.

Morbidity during chronic schistosomiasis has been associated with the induction and modulation of type-2 granulomatous inflammatory response induced by antigens secreted by the eggs, which become trapped in capillary venules of the host tissues, especially in the liver and intestines. IL-33, an alarmin released after cell damage, binds to its ST2 (suppressor of tumorigenicity 2) receptor, expressed in an variety of immune cells, including ILC2 and macrophages, and stimulates the early production of IL-5 and IL-13, which leads to eosinophil infiltration and activation of a Th2 response. However, the role of IL-33/ST2 activation on Schistosoma-induced granuloma formation and modulation is mostly unknown. In the current work, we comparatively evaluated the immune response and granuloma formation in wild-type BALB/c (WT) and BALB/c mice genetically deficient in the IL-33 receptor (ST2-/-) experimentally infected with Schistosoma mansoni. Mice were infected with 25 or 50 S. mansoni cercariae and followed for up to 14 weeks to assess mortality. Mice from each experimental group were comparatively evaluated for parasite burden, liver immune response, and granuloma appearance during acute and chronic schistosomiasis. Our data showed that the number of circulating worms and eggs retained in the liver and eliminated in the feces was similar in WT and ST2-/- infected mice, but infected ST2-/- mice presented an enhanced rate of mortality. Interestingly, the production of type-2 cytokines by soluble egg antigens (SEA)-stimulated spleen cells, the serum concentrations of IL-5 and Immunoglobulin (Ig)-E, and the level of parasite-reactive IgG1 were similar in infected mice of both experimental groups. The concentrations of IL-4, IL-5, IL-13, and IFN-γ in liver homogenate of infected mice also did not differ between the strains at acute schistosomiasis, but there was a significant increase in IL-17 levels in ST2-/- infected mice at this phase. On the other hand, IL-4, IL-13, IL-10, IL-17, and IFN-γ concentrations were reduced and the ratios of IL-4/IFN-γ and IL-17/IFN-γ were higher in liver homogenate of chronically infected ST2-/- mice, suggesting unbalanced Th2 and Th17 responses. Moreover, liver granulomas of ST2-/- mice were larger and disorganized, showing an intense cellular infiltrate, rich in eosinophils and neutrophils. Our results suggest that the absence of the IL-33/ST2 pathway is not essential for the Schistosoma-induced Th2 response, but is necessary to prevent host mortality by modulating granuloma-mediated pathology.

B Cells Adapt Their Nuclear Morphology to Organize the Immune Synapse and Facilitate Antigen Extraction.

Upon interaction with immobilized antigens, B cells form an immune synapse where actin remodeling and re-positioning of the microtubule-organizing center (MTOC) together with lysosomes can facilitate antigen extraction. B cells have restricted cytoplasmic space, mainly occupied by a large nucleus, yet the role of nuclear morphology in the formation of the immune synapse has not been addressed. Here we show that upon activation, B cells re-orientate and adapt the size of their nuclear groove facing the immune synapse, where the MTOC sits, and lysosomes accumulate. Silencing the nuclear envelope proteins Nesprin-1 and Sun-1 impairs nuclear reorientation towards the synapse and leads to defects in actin organization. Consequently, B cells are unable to internalize the BCR after antigen activation. Nesprin-1 and Sun-1-silenced B cells also fail to accumulate the tethering factor Exo70 at the center of the synaptic membrane and display defective lysosome positioning, impairing efficient antigen extraction at the immune synapse. Thus, changes in nuclear morphology and positioning emerge as critical regulatory steps to coordinate B cell activation.

Expansion of T regulatory lymphocytes by murine bone marrow dendritic cells previously stimulated with Anisakis simplex larval antigens

BACKGROUND Anisakis simplex antigens present immunomodulatory properties by the induction of tolerogenic dendritic cells (DCs) in mice. OBJECTIVES To study the capacity of DCs stimulated with A. simplex excretory-secretory (ES) or crude extract (CE) to generate Tregs. To investigate in vitro effects of antigens on the metabolic activity of splenocytes induced by LPS or CpG. METHODS Phenotypic and functional characterization of T cells co-cultured with A. simplex-pulsed DCs was performed by flow cytometry. Lymphocyte mitochondrial respiratory activity was estimated by the Alamar Blue® Assay. FINDINGS In C57BL/6J, CD4+CD25-Foxp3+ and CD8+CD25-Foxp3+ populations increased by CE-stimulated-DCs. In BALB/c, CE-stimulated-DCs caused the expansion of CD4+CD25+Foxp3+IL-10+ and CD8+CD25+Foxp3+IL-10+. IFN-γ expression raised in BALB/c CD4+CD25+ and CD4+CD25- for CE and ES, respectively. ES-stimulated-DCs increased CD4+CD25+ Foxp3+ and CD8+CD25- Foxp3+ expression in T cells. The association of ES or CE with LPS produced the increase in splenocyte activity in C57BL/6J. The association of CE with CpG decreased the proliferation caused by CpG in C57BL/6J. MAIN CONCLUSIONS A. simplex increase the frequency of Tregs, which in turn produce IL-10 and IFN-γ. The host genetic base is essential in the development of anti-Anisakis immune responses (Th2, Th1, Treg).

Tissue expression of antigens of ABH blood groups in species of New World Monkeys (Aotus infulatus, Callithrix jacchus, Sapajus apella and Saimiri sciureus).

ABH antigens are histo-antigens, but were first described on the surface of human erythrocytes. They are found in those cells only in great apes and humans, while in more primitive animals they are found in tissues and body fluids. ABH antigens are mainly distributed in tissues that are in contact with the external environment and may serve as ligands for pathogens in tissues or block their connection. Description of the distribution of these molecules in non-human primate tissues is restricted to a few tissues and species. This paper describes the expression of human A, B and H type antigens in different organs from four species of New World Primates, obtained from the Centro Nacional de Primatas, as well as comparing that expression with what has been described for humans. In this study, although the tissue description of the antigens is similar to the genetic model for humans, some differences in expression between some organs from those species and those of humans were found. The differences occurred mainly in endodermal organs that have secretory functions and are probably under the control of the human-type FUT-2 enzyme. In the mesodermal-origin organs there was a reduction or absence of A and B antigen marking, particularly in the H precursor substance, indicating that those organs are under the control of the human-type FUT-1 enzyme. These findings have demonstrated that there is similar ABH antigen reactivity in tissue distribution between the species, although there are some species-specific cases.

Neuroprotective effect of ACTH on collagenase-induced peri-intraventricular hemorrhage in newborn male rats.

Peri-intraventricular hemorrhage (PIVH) is a common and serious prematurity-related complication in neonates. Adrenocorticotropic hormone (ACTH) has neuroprotective actions and is a candidate to ameliorate brain damage following PIVH. Here, we tested the efficacy of ACTH1-24 on a collagenase-induced lesion of the germinal matrix (GM) in newborn male rats. Animals received microinjection of the vehicle (PBS, 2 µl) or collagenase type VII (0.3 IU) into the GM/periventricular tissue on postnatal day (PN) 2. Twelve hours later pups received microinjection of either the agonist ACTH1-24 (0.048 mg/kg), or the antagonist SHU9119 (antagonist of MCR3/MCR4 receptors, 0.01 mg/kg), or their combination. Morphological outcomes included striatal injury extension, neuronal and glial cells counting, and immunohistochemical expression of brain lesion biomarkers ipsilateral and contralateral to the hemorrhagic site. Data were evaluated on PN 8. Collagenase induced PIVH and severe ipsilateral striatal lesion. ACTH1-24 dampened the deleterious effects of collagenase-induced hemorrhage in significantly reducing the extension of the damaged area, the striatal neuronal and glial losses, and the immunoreactive expression of the GFAP, S100ß, and NG2-glia biomarkers in the affected periventricular area. SHU9119 blocked the glial density rescuing effect of ACTH1-24. ACTH1-24 could be further evaluated to determine its suitability for preclinical models of PVH in premature infants.

Latexin expression correlated with mineralization of articular cartilage during progression of post-traumatic osteoarthritis in a rat model.

As latexin has been linked with chondrocyte hypertrophic differentiation it is possible that this protein may also be involved in the mineralization of cartilage in OA. Therefore, we correlated latexin expression with the mineralization marker, alkaline phosphatase and determined the mineral deposition in the articular cartilage by analyzing the Ca/P ratio and the collagen fibrils pattern, during the progression of post-traumatic OA in a rat model. OA was induced by medial meniscectomy and post-surgery exercise for 5, 10, 20 and 45 days. Protein expression in articular cartilage was evaluated by immunofluorescence, histochemistry and Western blot. Minerals and structure of collagen fibrils in the superficial zone of cartilage were analyzed by energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) respectively. Protein expression analysis showed time-dependent up-regulation of latexin during OA progression. In the cartilage, latexin expression correlated with the expression and activity of alkaline phosphatase. EDX of the superficial zone of cartilage showed a Ca/P ratio closer to theoretical values for basic calcium phosphate minerals. The presence of minerals was also analyzed indirectly with AFM, as the collagen fibril pattern was less evident in the mineralized tissue. Latexin is expressed in articular cartilage from the early stages of post-traumatic OA; however, minerals were detected after latexin expression was up-regulated, indicating that its activity precedes and remains during the pathological mineralization of cartilage. Thus, our results contribute to the identification of molecules involved in the mineralization of articular chondrocytes.

The E3 ubiquitin ligase Itch restricts antigen-driven B cell responses.

The E3 ubiquitin ligase Itch regulates antibody levels and prevents autoimmune disease in humans and mice, yet how Itch regulates B cell fate or function is unknown. We now show that Itch directly limits B cell activity. While Itch-deficient mice displayed normal numbers of preimmune B cell populations, they showed elevated numbers of antigen-experienced B cells. Mixed bone marrow chimeras revealed that Itch acts within B cells to limit naive and, to a greater extent, germinal center (GC) B cell numbers. B cells lacking Itch exhibited increased proliferation, glycolytic capacity, and mTORC1 activation. Moreover, stimulation of these cells in vivo by WT T cells resulted in elevated numbers of GC B cells, PCs, and serum IgG. These results support a novel role for Itch in limiting B cell metabolism and proliferation to suppress antigen-driven B cell responses.

Studying MHC Class II Presentation of Immobilized Antigen by B Lymphocytes.

The ability of B lymphocytes to capture external antigens (Ag) and present them as peptide fragments, loaded on major histocompatibility complex (MHC) class II molecules, to CD4+ T cells is a crucial part of the adaptive immune response. This allows for T-B cooperation, a cellular communication that is required for B cells to develop into germinal centers (GC) and form mature high affinity antibody producing cells and to further develop B cell memory. MHC class II antigen presentation by B lymphocytes is a multistep process involving (1) Recognition and capture of external Ag by B lymphocytes through their B cell receptor (BCR), (2) Ag processing, which comprises the degradation of Ag in internal compartments within the B cell and loading of the corresponding peptide fragments on MHC class II molecules, and (3) Presentation of MHCII-peptide complexes to CD4+ T cells. Here, we describe how to study the biochemical and morphological changes that occur in B lymphocytes at these three major levels.

Proteasome Dependent Actin Remodeling Facilitates Antigen Extraction at the Immune Synapse of B Cells.

Engagement of the B cell receptor (BCR) with surface-tethered antigens leads to the formation of an immune synapse (IS), where cell signaling and antigen uptake are tightly coordinated. Centrosome re-orientation to the immune synapse has emerged as a critical regulatory step to guide the local recruitment and secretion of lysosomes, which can facilitate the extraction of immobilized antigens. This process is coupled to actin remodeling at the centrosome and at the immune synapse, which is crucial to promote cell polarity. How B cells balance both pools of actin cytoskeleton to achieve a polarized phenotype during the formation of an immune synapse is not fully understood. Here, we reveal that B cells rely on proteasome activity to achieve this task. The proteasome is a multi-catalytic protease that degrades cytosolic and nuclear proteins and its dysfunction is associated with diseases, such as cancer and autoimmunity. Our results show that resting B cells contain an active proteasome pool at the centrosome, which is required for efficient actin clearance at this level. As a result of proteasome inhibition, activated B cells do not deplete actin at the centrosome and are unable to separate the centrosome from the nucleus and thus display impaired polarity. Consequently, lysosome recruitment to the immune synapse, antigen extraction and presentation are severely compromised in B cells with diminished proteasome activity. Additionally, we found that proteasome inhibition leads to impaired actin remodeling at the immune synapse, where B cells display defective spreading responses and distribution of key signaling molecules at the synaptic membrane. Overall, our results reveal a new role for the proteasome in regulating the immune synapse of B cells, where the intracellular compartmentalization of proteasome activity controls cytoskeleton remodeling between the centrosome and synapse, with functional repercussions in antigen extraction and presentation.

Leucemia linfoide crónica de células B: revisión de sus aspectos etiopatogénicos, moleculares y pronósticos / B-cell chronic lymphoid leukemia: a review of its etiopathogenic, molecular and prognostic aspects

La leucemia linfoide crónica (LLC) es una neoplasia maligna que afecta principalmente a pacientes de mediana edad y ancianos. Se caracteriza por la proliferación de linfocitos morfológicamente maduros pero inmunoincompetentes que se acumulan en sangre periférica, médula ósea y tejido linfático. Presenta gran heterogeneidad clínica. Se describen diversos fenotipos, aunque predomina la expansión clonal de células B CD5+CD23+. Los factores pronósticos en la LLC incluyen el subgrupo citogenético, estado mutacional de inmunoglobulina, la expresión de ZAP-70, CD38 y CD49d. El tratamiento se basa en usar modernos algoritmos terapéuticos aprobados, que produzcan mayores respuestas y menores eventos secundarios, en lograr la remisión clínica completa y mejorar la calidad de vida de estos pacientes(AU)

Chronic lymphocytic leukemia (CLL) is a malignancy that mainly affects middle-aged and elderly patients. It is characterized by the proliferation of morphologically mature but immunoincompetent lymphocytes that accumulate in blood, bone marrow and lymphatic tissue. It presents great clinical heterogeneity. Several phenotypes are described, although the clonal expansion of CD5 + CD23 + B cells predominates. Prognostic factors include the cytogenetic subgroup, immunoglobulin mutational status, expression of ZAP-70, CD38, and CD49d. The treatment is based on using modern approved therapeutic algorithms that produce greater responses and minor secondary events, to achieve complete clinical remission and to improve the quality of life of these patients(AU)

Differential expression analysis for subolesin in Rhipicephalus microplus infected with Anaplasma marginale.

Rhipicephalus microplus (formerly Boophilus microplus) ticks are potential vectors of several pathogens of livestock especially in tropical and subtropical regions where may have substantial effects on economic development. Among tick-borne pathogens, Anaplasma marginale is considered one of the most important in domestic and wild ruminants worldwide. Different molecular mechanisms have been employed by both ticks and these intracellular pathogens, in order to be able to adapt and survive. Subolesin, originally called 4D8, is an evolutionarily well-preserved protein among ixodid tick species. This new antigen was found to be protective against tick infestations when used as a vaccine, as it has an essential role in tick blood digestion, development and infection of host cells by A. marginale. Recent studies have demonstrated that infection of both tick and vertebrate host cells with this microorganism changed gene expression. Therefore, the main objective of this study was to investigate subolesin expression in uninfected and A. marginale-infected R. microplus salivary glands by real-time reverse transcriptase (RT)-PCR. To analyze the differential expression of the recombinant protein subolesin, the gene was previously expressed from ticks infected with A. marginale. Results from this study revealed that, the expression of subolesin was significantly higher in salivary glands of infected R. microplus in comparison to uninfected ones.

Tuning B cell responses to antigens by cell polarity and membrane trafficking.

The capacity of B lymphocytes to produce specific antibodies, particularly broadly neutralizing antibodies that provide immunity to viral pathogens has positioned them as valuable therapeutic targets for immunomodulation. To become competent as antibody secreting cells, B cells undergo a series of activation steps, which are triggered by the recognition of antigens frequently displayed on the surface of other presenting cells. Such antigens elicit the formation of an immune synapse (IS), where local cytoskeleton rearrangements coupled to mechanical forces and membrane trafficking orchestrate the extraction and processing of antigens in B cells. In this review, we discuss the molecular mechanisms that regulate polarized membrane trafficking and mechanical properties of the immune synapse, as well as the potential extracellular cues from the environment, which may impact the ability of B cells to sense and acquire antigens at the immune synapse. An integrated view of the diverse cellular mechanisms that shape the immune synapse will provide a better understanding on how B cells are efficiently activated.

Nucleoside-modified mRNA vaccines induce potent T follicular helper and germinal center B cell responses.

T follicular helper (Tfh) cells are required to develop germinal center (GC) responses and drive immunoglobulin class switch, affinity maturation, and long-term B cell memory. In this study, we characterize a recently developed vaccine platform, nucleoside-modified, purified mRNA encapsulated in lipid nanoparticles (mRNA-LNPs), that induces high levels of Tfh and GC B cells. Intradermal vaccination with nucleoside-modified mRNA-LNPs encoding various viral surface antigens elicited polyfunctional, antigen-specific, CD4+ T cell responses and potent neutralizing antibody responses in mice and nonhuman primates. Importantly, the strong antigen-specific Tfh cell response and high numbers of GC B cells and plasma cells were associated with long-lived and high-affinity neutralizing antibodies and durable protection. Comparative studies demonstrated that nucleoside-modified mRNA-LNP vaccines outperformed adjuvanted protein and inactivated virus vaccines and pathogen infection. The incorporation of noninflammatory, modified nucleosides in the mRNA is required for the production of large amounts of antigen and for robust immune responses.

A Gene Constellation in Avian Influenza A (H7N9) Viruses May Have Facilitated the Fifth Wave Outbreak in China.

The 2016-2017 epidemic of influenza A (H7N9) virus in China prompted concern that a genetic change may underlie increased virulence. Based on an evolutionary analysis of H7N9 viruses from all five outbreak waves, we find that additional subclades of the H7 and N9 genes have emerged. Our analysis indicates that H7N9 viruses inherited NP genes from co-circulating H7N9 instead of H9N2 viruses. Genotypic diversity among H7N9 viruses increased following wave I, peaked during wave III, and rapidly deceased thereafter with minimal diversity in wave V, suggesting that the viruses entered a relatively stable evolutionary stage. The ZJ11 genotype caused the majority of human infections in wave V. We suggest that the largest outbreak of wave V may be due to a constellation of genes rather than a single mutation. Therefore, continuous surveillance is necessary to minimize the threat of H7N9 viruses.

Production of Recombinant Factor VIII in Human Cell Lines.

Human cell lines can produce recombinant proteins much more similar to their natural counterpart, compared to other mammalian cell lines, reducing potential immunogenic reactions. Recombinant proteins produced in nonhuman cells can have in its structure glycan epitopes, such as Galα1,3-Gal (alpha-Gal) and N-glycolylneuraminic acid (Neu5Gc) residues, that are antigenic to humans and can potentially affect the efficacy of the recombinant product. Therefore, the production of recombinant factor VIII (rFVIII) in human cell lines is a new approach to avoid nonhuman glycosylation. Here, we describe a protocol to produce rFVIII in the human cell line SK-HEP, using a lentiviral vector to produce high quantities of the recombinant protein.

Update on Aire and thymic negative selection.

Twenty years ago, the autoimmune regulator (Aire) gene was associated with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy, and was cloned and sequenced. Its importance goes beyond its abstract link with human autoimmune disease. Aire identification opened new perspectives to better understand the molecular basis of central tolerance and self-non-self distinction, the main properties of the immune system. Since 1997, a growing number of immunologists and molecular geneticists have made important discoveries about the function of Aire, which is essentially a pleiotropic gene. Aire is one of the functional markers in medullary thymic epithelial cells (mTECs), controlling their differentiation and expression of peripheral tissue antigens (PTAs), mTEC-thymocyte adhesion and the expression of microRNAs, among other functions. With Aire, the immunological tolerance became even more apparent from the molecular genetics point of view. Currently, mTECs represent the most unusual cells because they express almost the entire functional genome but still maintain their identity. Due to the enormous diversity of PTAs, this uncommon gene expression pattern was termed promiscuous gene expression, the interpretation of which is essentially immunological - i.e. it is related to self-representation in the thymus. Therefore, this knowledge is strongly linked to the negative selection of autoreactive thymocytes. In this update, we focus on the most relevant results of Aire as a transcriptional and post-transcriptional controller of PTAs in mTECs, its mechanism of action, and its influence on the negative selection of autoreactive thymocytes as the bases of the induction of central tolerance and prevention of autoimmune diseases.