From Mysterious Supernatant Entity to miRNA-150 in Antigen-Specific Exosomes: a History of Hapten-Specific T Suppressor Factor

Extracellular Vesicles—Oral Therapeutics of the Future

Considered an artifact just after discovery, the possibility of oral delivery of extracellular vesicles (EVs) and their functional cargos has recently gained much research attention. EVs from various sources, including edible plants, milk, bacteria and mammalian cells, have emerged as a platform for miRNA and drug delivery that seem to induce the expected immune effects locally and in distant tissues after oral administration. Such a possibility greatly expands the clinical applicability of EVs. The present review summarizes research findings that either support or deny the biological/therapeutical activity of orally administered EVs and their role in cross-species and cross-kingdom signaling.

Role and Function of T Cell-Derived Exosomes and Their Therapeutic Value

Exosomes are membrane-bound extracellular vesicles that are produced in the endosomal compartment of most eukaryotic cells. Containing proteins, RNA, and DNA, exosomes mediate intercellular communication between different cell types by transferring their contents and thus are involved in numerous physiological and pathological processes. T cells are an indispensable part of adaptive immunity, and the functions of T cell-derived exosomes have been widely studied. In the more than three decades since the discovery of exosomes, several studies have revealed that T cell-derived exosomes play a novel role in cell-to-cell signaling, especially in inflammatory responses, autoimmunity, and infectious diseases. In this review, we will summarize the function of T cell-derived exosomes and their therapeutic potential.

Antibodies Enhance the Suppressive Activity of Extracellular Vesicles in Mouse Delayed-Type Hypersensitivity

Previously, we showed that mouse delayed-type hypersensitivity (DTH) can be antigen-specifically downregulated by suppressor T cell-derived miRNA-150 carried by extracellular vesicles (EVs) that target antigen-presenting macrophages. However, the exact mechanism of the suppressive action of miRNA-150-targeted macrophages on effector T cells remained unclear, and our current studies aimed to investigate it. By employing the DTH mouse model, we showed that effector T cells were inhibited by macrophage-released EVs in a miRNA-150-dependent manner. This effect was enhanced by the pre-incubation of EVs with antigen-specific antibodies. Their specific binding to MHC class II-expressing EVs was proved in flow cytometry and ELISA-based experiments. Furthermore, by the use of nanoparticle tracking analysis and transmission electron microscopy, we found that the incubation of macrophage-released EVs with antigen-specific antibodies resulted in EVs’ aggregation, which significantly enhanced their suppressive activity in vivo. Nowadays, it is increasingly evident that EVs play an exceptional role in intercellular communication and selective cargo transfer, and thus are considered promising candidates for therapeutic usage. However, EVs appear to be less effective than their parental cells. In this context, our current studies provide evidence that antigen-specific antibodies can be easily used for increasing EVs’ biological activity, which has great therapeutic potential.

The complex functions of microRNA-150 in allergy, autoimmunity and immune tolerance

<abstract> <p>At present, special efforts are being made to develop the strategies allowing for activation of long-lasting antigen-specific immune tolerance in therapy of allergic and autoimmune diseases. Some of these therapeutic approaches are aimed at modulating cell functions at genetic level by using miRNA-based and miRNA-targeting treatments. Simultaneously, the crucial role of extracellular vesicles as natural miRNA conveyors is highlighted for induction of antigen-specific immune tolerance, especially that they appear to be easily manipulatable for therapeutic applications. Among other immune-related miRNAs, miR-150 is getting special attention as it is differently expressed by immune cells at various stages of their maturation and differentiation. In addition, miR-150 is involved in different signaling cascades orchestrating humoral and cell-mediated mechanisms of both innate and adaptive immune responses. Therefore, miR-150 is considered a master regulator of immunity in mammals. Currently, physiological miR-150-dependent regulatory circuits and causes of their malfunctioning that underlie the pathogenesis of allergic and autoimmune disorders are being unraveled. Thus, present review summarizes the current knowledge of the role of miR-150 in the pathogenesis and complications of these diseases. Furthermore, the involvement of miR-150 in regulation of immune responses to allergens and self-antigens and in induction of antigen-specific immune tolerance is discussed with the special emphasis on the therapeutic potential of this miRNA.</p> </abstract>

Perspectives in Manipulating EVs for Therapeutic Applications: Focus on Cancer Treatment

Extracellular vesicles (EVs) receive special attention from oncologists due to their assumed usefulness as prognostic markers, vaccines to induce anti-cancer immune response, and physiological delivery tools. The latter application, which supports the reduction of side effects of treatment, is still fraught with many challenges, including established methods for loading EVs with selected cargo and directing them towards target cells. EVs could be loaded with selected cargo either in vitro using several physicochemical techniques, or in vivo by modification of parental cell, which may have an advantage over in vitro procedures, since some of them significantly influence EVs’ properties. Otherwise, our research findings suggest that EVs could be passively supplemented with micro RNAs (miRNAs) or miRNA antagonists to induce expected biological effect. Furthermore, our observations imply that antigen-specific antibody light chains could coat the surface of EVs to increase the specificity of cell targeting. Finally, the route of EVs’ administration also determines their bioavailability and eventually induced therapeutic effect. Besides, EV membrane lipids may possibly possess immune adjuvant activity. The review summarizes the current knowledge on the possibilities to manipulate EVs to use them as a delivery tool, with the special emphasis on anti-cancer therapy.

Approaches to inducing antigen-specific immune tolerance in allergy and autoimmunity: Focus on antigen-presenting cells and extracellular vesicles

Increasing prevalence of allergic and autoimmune diseases urges clinicians and researchers to search for new and efficient treatments. Strategies that activate antigen-specific immune tolerance and simultaneously maintain immune reactivity to all other antigens deserve special attention. Accordingly, antigen-presenting cells (APCs) seem to be the best suited for orchestrating these mechanisms by directing T cell immune responses towards a tolerant subtype. Recent advances in understanding cell-to-cell communication via extracellular vesicles (EVs) make the latter promising candidates for reprogramming APCs towards a tolerant phenotype, and for mediating tolerogenic APC function. Thus, comprehensive studies have been undertaken to describe the interactions of APCs and EVs naturally occurring during immune tolerance induction, as well as to develop EV-based manoeuvres enabling the induction of immune tolerance in an antigen-specific manner. In this review, we summarize the findings of relevant studies, with a special emphasis on future perspectives on their translation to clinical practice.

Syngeneic red blood cell-induced extracellular vesicles suppress delayed-type hypersensitivity to self-antigens in mice

BACKGROUND

At present, the role of autologous cells as antigen carriers inducing immune tolerance is appreciated. Accordingly, intravenous administration of haptenated syngeneic mouse red blood cells (sMRBC) leads to hapten-specific suppression of contact hypersensitivity (CHS) in mice, mediated by light chain-coated extracellular vesicles (EVs). Subsequent studies suggested that mice intravenously administered with sMRBC alone may also generate regulatory EVs, revealing the possible self-tolerogenic potential of autologous erythrocytes.

OBJECTIVES

The current study investigated the immune effects induced by mere intravenous administration of a high dose of sMRBC in mice.

METHODS

The self-tolerogenic potential of EVs was determined in a newly developed mouse model of delayed-type hypersensitivity (DTH) to sMRBC. The effects of EV's action on DTH effector cells were evaluated cytometrically. The suppressive activity of EVs, after coating with anti-hapten antibody light chains, was assessed in hapten-induced CHS in wild-type or miRNA-150^-/- mice.

RESULTS

Intravenous administration of sMRBC led to the generation of CD9 + CD81+ EVs that suppressed sMRBC-induced DTH in a miRNA-150-dependent manner. Furthermore, the treatment of DTH effector cells with sMRBC-induced EVs decreased the activation of T cells but enhanced their apoptosis. Finally, EVs coated with antibody light chains inhibited hapten-induced CHS.

CONCLUSIONS AND CLINICAL RELEVANCE

The current study describes a newly discovered mechanism of self-tolerance induced by the intravenous delivery of a high dose of sMRBC that is mediated by EVs in a miRNA-150-dependent manner. This mechanism implies the concept of naturally occurring immune tolerance, presumably activated by overloading of the organism with altered self-antigens.

Delayed-Type Hypersensitivity Underlying Casein Allergy Is Suppressed by Extracellular Vesicles Carrying miRNA-150

In patients with non-IgE-mediated milk allergy, a cellular mechanism of delayed-type hypersensitivity (DTH) is considered. Recent findings prove that cell-mediated reactions can be antigen-specifically inhibited by extracellular vesicles (EVs) carrying miRNA-150. We sought to establish a new mouse model of DTH to casein and test the possibility of antigen-specific suppression of the inflammatory reaction. To produce soluble antigenic peptides, casein was subjected to alkaline hydrolysis. DTH reaction to casein was induced in CBA, C57BL/6, and BALB/c mice by intradermal (id) injection of the antigen. Cells collected from spleens and lymph nodes were positively or negatively selected and transferred to naive recipients intravenously (iv). CBA mice were tolerized by iv injection of mouse erythrocytes conjugated with casein antigen and following id immunization with the same antigen. Suppressive EVs were harvested from cell cultures and serum of tolerized donors by means of ultrafiltration and ultracentrifugation for further therapeutic utilization. The newly established mouse model of DTH to casein was mediated by CD4+ Th1 cells and macrophages, while EVs produced by casein-tolerized animals effectively suppressed effector cell response, in an miRNA-150-dependent manner. Altogether, our observations contribute to the current understanding of non-IgE-mediated allergy to casein and of the possibilities to downregulate this reaction.

Regulatory B cell phenotype and mechanism of action: the impact of stimulating conditions

A diverse population of regulatory B (Breg) cells reportedly exhibits significant immunomodulatory effects in various models of inflammatory responses and infectious diseases caused by bacteria, viruses or parasites. Breg cells contribute to maintenance of homeostasis via IL-10 production and multiple IL-10-independent mechanisms. The current review describes various phenotypic and functional subsets of Breg cells in autoimmune and infectious diseases and discusses the impacts of experimental conditions that have been found to drive Breg cell differentiation.

Antibody Light Chains Dictate the Specificity of Contact Hypersensitivity Effector Cell Suppression Mediated by Exosomes

Antibody light chains (LCs), formerly considered a waste product of immunoglobulin synthesis, are currently recognized as important players in the activation of the immune response. However, very little is known about the possible immune regulatory functions of LCs. Recently, we reported that hapten-specific LCs coat miRNA-150-carrying exosomes produced by CD8+ suppressor T cells downregulating the contact hypersensitivity (CHS) reaction in an antigen-specific manner, in mice tolerized by intravenous administration of a high dose of hapten-coupled syngeneic erythrocytes. Thus, the current studies aimed at investigating the role of hapten-specific LCs in antigen-specific, exosome-mediated suppression of CHS effector cells. Suppressor T cell-derived exosomes from tolerized B-cell-deficient µMT^-/-, NKT-cell-deficient Jα18^-/-, and immunoglobulin-deficient JH^-/- mice were nonsuppressive, unless supplemented with LCs of specificity strictly respective to the hapten used for sensitization and CHS elicitation in mice. Thus, these observations demonstrate that B1-cell-derived LCs, coating exosomes in vivo and in vitro, actually ensure the specificity of CHS suppression. Our research findings substantially expand current understanding of the newly discovered, suppressor T cell-dependent tolerance mechanism by uncovering the function of antigen-specific LCs in exosome-mediated, cell⁻cell communication. This express great translational potential in designing nanocarriers for specific targeting of desired cells.

Chemical-induced contact allergy: from mechanistic understanding to risk prevention

Chemical allergens are small molecules able to form a sensitizing complex once they bound to proteins. One of the most frequent manifestations of chemical allergy is contact hypersensitivity, which can have serious impact on quality of life. Allergic contact dermatitis is a predominantly CD8 + T cell-mediated immune disease, resulting in erythema and eczema. Chemical allergy is of considerable importance to the toxicologist, who has the responsibility of identifying and characterizing the allergenic potential of chemicals, and estimating the risk they pose to human health. This review aimed at exploring the phenomena of chemical-induced contact allergy starting from a mechanistic understanding, immunoregulatory mechanisms, passing through the potency of contract allergen until the hazard identification, pointing out the in vitro models for assessing contact allergen-induced cell activation and the risk prevention.

The Relationship between RUNX3 Expression, Nursing Strategies and Nutritional Status in Elderly Patients with Advanced Gastric Cancer

BACKGROUND

The aim of this study was to explore the relationship between nutritional status and expression of RUNX3 in gastric cancer cells and to investigate the effects of nursing strategies on the nutritional status of elderly patients with advanced gastric cancer.

METHODS

Forty-eight elderly patients admitted at Affiliated Hospital of Qingdao University with advanced gastric cancer and 30 healthy controls were selected as subjects from 2014-15. The correlation between RNX3 gene expression and nutritional status of the gastric cancer patients was investigated. The patients with advanced gastric cancer who had low expression of RUNX3 gene were treated with holistic nursing while routine nursing was taken for those patients who had normal or high expression of RUNX3 gene. The nutritional statuses of these patients were evaluated after 3 months of nursing. After a follow-up of 1 year, the influence of different nursing methods on the survival time was evaluated.

RESULTS

Compared with normal gastric tissue, the expression of RUNX3 gene and protein in tissues of advanced gastric cancer were significantly decreased (P<0.01). Compared with patients with normal or high expressions of RUNX3, the nutritional statuses of advanced gastric cancer patients with low expressions of RUNX3 were lower (P<0.01). The nutritional statuses of patients with low expressions of RUNX3 were notably improved after holistic nursing, becoming equivalent to those with normal or high expression of RUNX3 who received routine nursing (P>0.05). The survival time of patients with low expression of RUNX3 who received holistic nursing were similar to patients with normal or high expression of RUNX3 who received routine nursing (P>0.05).

CONCLUSION

RUNX3 is correlated with the occurrence and development of advanced gastric cancer. The low nutritional status of elderly advanced gastric cancer patients with low expressions of RUNX3 can be significantly enhanced by holistic nursing, thereby prolonging survival time.

Melatonin treatment enhances therapeutic effects of exosomes against acute liver ischemia-reperfusion injury

This study tests the hypothesis that combined melatonin and exogenic adipose mesenchymal stem cell (ADMSC)-derived exosome treatment offers superior protection against liver ischemia-reperfusion (LIR) injury compared to either alone. In vitro studies utilized a macrophage cell line (RAW) pretreated with lipopolysaccharide and hepatocytes pretreated with melatonin or exosomes before hypoxia treatment, while in vitro experiments involved analyses of liver specimens from male adult Sprague-Dawley rats (n = 50) equally categorized into sham controls (SC), LIR only, LIR-exosome (100 µg, 30 minute post-LIR), LIR-melatonin (20 mg/kg, 30 minute post-LIR and 50 mg/kg at 6 and 18 hours post-LIR), and LIR-exosome-melatonin groups. In vitro studies showed suppression of inflammation (MIF, MMP-9, IL-1β, TNF-α, COX-2) and oxidative stress (NOX-1, NOX-2, oxidized protein)/apoptosis (cleaved caspase 3 and PARP) by exosome and exosome/melatonin treatment, respectively (all P<0.001). In vivo data demonstrated lowest liver injury score and plasma AST concentrations in LIR-exosome-melatonin group compared with other groups (P<0.001). Besides, expressions of inflammatory markers at protein (ICAM-1, IL-1β, MMP-9, TNF-α, NF-κB, RANTES) and cellular (CD3+, CD4+, CD8+, CD161+, CD11+, CD14+, F4/80) levels, and protein expressions of apoptosis (cleaved caspase-3, PARP), oxidative stress (NOX-1, NOX-2), DNA damage (γ-H2AX) and mitochondrial damage (cytosolic cytochrome-C) markers displayed a pattern similar to that of liver injury score, whereas protein expression of anti-oxidants (HO-1, NQO-1) showed progressive increase from SC to the combined treatment group (all P<0.001). In conclusion, combined exosome-melatonin regimen was superior to either alone in protecting the liver against ischemia-reperfusion injury.

Functions of Cancer-Derived Extracellular Vesicles in Immunosuppression

Extracellular vesicles, including exosomes, constitute an important element of intercellular communication by carrying a variety of molecules from producer to target cells. The transport of mRNA and miRNA can directly modulate gene expression in the target cells. The miRNA content in exosomes is characteristic for the cell from which the vesicles were derived enabling the usage of exosomes as biomarkers for the diagnosis various diseases, including cancer. Cancer-derived exosomes support the survival and progression of tumors in many ways and also contribute to the neutralization of the anti-cancer immune response. Exosomes participate in all known mechanisms by which cancer evades the immune system. They influence the differentiation and activation of immune suppressor cells, they modulate antigen presentation, and are able to induce T-cell apoptosis. Although cancer-derived exosomes mainly suppress the immune system and facilitate tumor progression, they are also important sources of tumor antigens with potential clinical application in stimulating immune responses. This review summarizes how exosomes assist cancer to escape immune recognition and to acquire control over the immune system.

Functions of Exosomes and Microbial Extracellular Vesicles in Allergy and Contact and Delayed-Type Hypersensitivity

Extracellular vesicles, such as exosomes, are newly recognized intercellular conveyors of functional molecular mechanisms. Notably, they transfer RNAs and proteins between different cells that can then participate in the complex pathogenesis of allergic and related hypersensitivity responses and disease mechanisms, as described herein. This review highlights this important new appreciation of the in vivo participation of such extracellular vesicles in the interactions between allergy-mediating cells. We take into account paracrine epigenetic exchanges mediated by surrounding stromal cells and the endocrine receipt of exosomes from distant cells via the circulation. Exosomes are natural ancient nanoparticles of life. They are made by all cells and in some form by all species down to fungi and bacteria, and are present in all fluids. Besides a new focus on their role in the transmission of genetic regulation, exosome transfer of allergens was recently shown to induce allergic inflammation. Importantly, regulatory and tolerogenic exosomes can potently inhibit allergy and hypersensitivity responses, usually acting nonspecifically, but can also proceed in an antigen-specific manner due to the coating of the exosome surface with antibodies. Deep analysis of processes mediated by exosomes should result in the development of early diagnostic biomarkers, as well as allergen-specific, preventive and therapeutic strategies. These will likely significantly diminish the risks of current allergen-specific parenteral desensitization procedures, and of the use of systemic immunosuppressive drugs. Since extracellular vesicles are physiological, they can be fashioned for the specific delivery of therapeutic molecular instructions through easily tolerated, noninvasive routes, such as oral ingestion, nasal administration, and perhaps even inhalation.

Free Extracellular miRNA Functionally Targets Cells by Transfecting Exosomes from Their Companion Cells

Lymph node and spleen cells of mice doubly immunized by epicutaneous and intravenous hapten application produce a suppressive component that inhibits the action of the effector T cells that mediate contact sensitivity reactions. We recently re-investigated this phenomenon in an immunological system. CD8+ T lymphocyte-derived exosomes transferred suppressive miR-150 to the effector T cells antigen-specifically due to exosome surface coat of antibody light chains made by B1a lymphocytes. Extracellular RNA (exRNA) is protected from plasma RNases by carriage in exosomes or by chaperones. Exosome transfer of functional RNA to target cells is well described, whereas the mechanism of transfer of exRNA free of exosomes remains unclear. In the current study we describe extracellular miR-150, extracted from exosomes, yet still able to mediate antigen-specific suppression. We have determined that this was due to miR-150 association with antibody-coated exosomes produced by B1a cell companions of the effector T cells, which resulted in antigen-specific suppression of their function. Thus functional cell targeting by free exRNA can proceed by transfecting companion cell exosomes that then transfer RNA cargo to the acceptor cells. This contrasts with the classical view on release of RNA-containing exosomes from the multivesicular bodies for subsequent intercellular targeting. This new alternate pathway for transfer of exRNA between cells has distinct biological and immunological significance, and since most human blood exRNA is not in exosomes may be relevant to evaluation and treatment of diseases.