Neuropilin-1 is present on Foxp3+ T regulatory cell-derived small extracellular vesicles and mediates immunity against skin transplantation

Immune activation and regulation mediated by immune cell-derived EVs (iEVs)

Extracellular vesicles (EVs), secreted by all cellular organisms, are pivotal mediators of intercellular communication. By transporting biologically active cargos such as proteins, lipids, and nucleic acids, EVs facilitate transfer of molecular signals, effectively reflecting the characteristics of their parent cells. Immune cellderived EVs (iEVs) play a crucial role in the activation and regulation of both adaptive and innate immune responses. In the context of immune activation, iEVs drive immune cell development and activation, as well as enhance antigen presentation through both direct and cross-dressing mechanisms. Furthermore, iEVs act as signaling entities within immunological synapses, significantly amplifying immune response efficiency. In immune regulation, iEVs modulate the expression of immune checkpoint (IC) molecules and sustain immune homeostasis by transporting immunosuppressive cytokines and microRNAs, thereby mitigating excessive immune reactions. Nevertheless, the mechanistic underpinnings of iEV-mediated immune cell activation, antigen presentation, and immunoregulation remain inadequately explored. This review provides a comprehensive overview of the functions of iEVs from diverse immune cell origins and underlying mechanisms. It also examines cutting-edge engineering strategies targeting iEVs and their parent cells, while discussing their promising applications in oncology and immune-related diseases. These insights lay the foundation for the rational development of next-generation immunotherapies. While promising, the clinical translation of iEVs is hindered by low yield, high batch-to-batch variability, and insufficient targeting efficiency. The final section discusses key challenges and potential solutions.

Drug-loaded microneedle patches containing regulatory T cell-derived exosomes for psoriasis treatment

Psoriasis is a chronic inflammatory skin disease characterized by epidermal hyperplasia, skin inflammation, and immune dysregulation. These factors contribute to the persistent progression of the disease. While addressing excessive keratinocyte proliferation or inhibiting inflammation may provide temporary therapeutic relief, unresolved immune dysregulation often exacerbates the condition. Therefore, comprehensive treatments that alleviate skin symptoms and regulate immune tolerance are urgently required. An ideal treatment would target multiple factors, including keratinocyte proliferation, inflammation, and immune tolerance, while minimizing systemic side effects. In this study, we developed a dissolvable hyaluronic acid microneedle patch containing regulatory T cell (Treg) exosomes loaded with dimethyl fumarate (DMF) (rExo@DMF MNs). DMF acts as an inhibitor of keratinocyte proliferation and an anti-inflammatory agent through NF-κB suppression and Nrf2 activation, inhibiting the production of pro-inflammatory cytokines and the activation of inflammatory cells. Delivering DMF via Treg exosomes enhances its retention at the lesion site. This system inhibits keratinocyte proliferation and migration, reduces pro-inflammatory cytokine release, and alleviates epidermal hyperplasia and inflammation in an imiquimod-induced psoriasis mouse model. Additionally, Treg exosomes modulate immune responses to promote tolerance. rExo@DMF MNs demonstrate immunomodulatory effects by inhibiting T helper 17 (Th17) cells and inducing regulatory immune cells such as Tregs and tolerogenic dendritic cells (tDCs) differentiation. rExo@DMF MNs alleviate skin symptoms and regulate immune cells in the skin, spleen, and lymph nodes, demonstrating both local and systemic immunoregulation with promising therapeutic potential for psoriasis. STATEMENT OF SIGNIFICANCE: Novel therapies are urgently needed to alleviate skin symptoms and regulate immunity, as current psoriasis treatments focus on symptom relief while neglecting the underlying immune dysfunction, resulting in limited efficacy. Moreover, systemic immunosuppression often leads to severe side effects. This study introduces a hybrid microneedle system (rExo@DMF MNs) that alleviates psoriasis symptoms and modulates immune responses locally and systemically. In addition, rExo@DMF MNs penetrate hyperkeratotic skin, ensuring targeted rExo@DMF release while minimizing systemic exposure and side effects. All components of the system, including hyaluronic acid (a key component of the skin matrix), regulatory T cell-derived exosomes, and DMF (a clinically validated drug), exhibit biocompatibility. This comprehensive approach addresses multiple pathogenic factors, promising an effective and safe psoriasis treatment.

The potential mechanisms of extracellular vesicles in transfusion-related adverse reactions: Recent advances

Blood transfusion is an irreplaceable clinical treatment. Blood components are differentiated and stored according to specific guidelines. Storage temperatures and times vary depending on the blood component, but they all release extracellular vesicles (EVs) during storage. Although blood transfusions can be life-saving, they can also cause many adverse transfusion reactions, among which the effects of EVs are of increasing interest to researchers. EVs are submicron particles that vary in size, composition, and surface biomarkers, are encapsulated by a lipid bilayer, and are not capable of self-replication. EVs released by blood cells are important contributors to pathophysiologic states through proinflammatory, coagulant, and immunosuppressive effects, which in turn promote or inhibit the associated disease phenotype. Therefore, this review explores the potential mechanisms of hematopoietic-derived EVs in transfusion-associated adverse reactions and discusses the potential of the latest proteomics tools to be applied to the analysis of EVs in the field of transfusion medicine with a view to reducing the risk of blood transfusion.

Reprogramming of Treg cell-derived small extracellular vesicles effectively prevents intestinal inflammation from PANoptosis by blocking mitochondrial oxidative stress

Inflammatory bowel disease (IBD) is a chronic relapsing immune-mediated inflammatory disorder of the alimentary tract without exact etiology. Mitochondrial reactive oxygen species (mtROS) derived from mitochondrial dysfunction impair intestinal barrier function, increase gut permeability, and facilitate immune cell invasion, and, therefore, are considered to have a pivotal role in the pathogenesis of IBD. Here, we reprogrammed regulatory T cell (Treg)-derived exosomes loaded with the antioxidant trace element selenium (Se) and decorated them with the synthetic mitochondria-targeting SS-31 tetrapeptide via a peptide linker. This linker can be cleaved by matrix metalloproteinases (MMPs) in inflammatory lesions. This actively targetable exosome-derived delivery system is protected from intestinal inflammation by scavenging excessive mtROS and preventing immunologically programmed cell death pyroptosis, necroptosis, and apoptosis, known as PANoptosis. Our results suggest that this engineered exosome delivery platform represents a promising targeted therapeutic strategy for the treatment of IBDs.

Neuropilin1-dependent paracrine signaling of cancer cells mediated by miRNA exosomal cargo

BACKGROUND

Neuropilin-1 (NRP1) is a transmembrane protein involved in surface receptor complexes for a variety of extracellular signals. NRP1 expression in human cancers is associated with prominent angiogenesis and advanced progression stage. However, the molecular mechanisms underlying NRP1 activity in the tumor microenvironment remain unclear. Notably, diffusible forms of NRP1 in the extracellular space have been reported, but their functional role is poorly understood.

METHODS

Extracellular vesicles (EV) were isolated from conditioned media of diverse cancer cells. The quality of exosome-enriched preparations was validated by the presence of specific markers in western blotting, as well as by light scattering and nanoparticle tracking analysis. Wound healing, transwell, and digital real-time migration assays were carried out to assess the activity of cancer cell-derived exosomes in the regulation of endothelial cells. RNA interference was applied to obtain NRP1 knock-down, and cDNA transfer to achieve its overexpression, in exosome-releasing cells. The micro-RNA profile carried by exosomes was investigated by Next Generation Sequencing. miRNA-Scope in situ hybridization was used to assess the transfer of miRNA exosome cargo to target cells, and immunofluorescence analysis revealed expression regulation of targeted proteins. miRNA activity was blocked by the use of specific antago-miRs.

RESULTS

In this study, we show that diverse human cancer cells release NRP1 embedded in exosome-like small extracellular vesicles, which mediate a previously unknown NRP1-dependent paracrine signaling mechanism regulating endothelial cell migration. By transcriptomic analysis of the cargo of NRP1-loaded exosomes, we found a significant enrichment of miR-210-3p, known to promote tumor angiogenesis. Gene knock-down and overexpression experiments demonstrated that the loading of miR-210-3p into exosomes is dependent on NRP1. Data furthermore indicate that the exosomes released through this NRP1-driven mechanism effectively transfer miR-210-3p to human endothelial cells, causing paracrine downregulation of the regulatory cue ephrin-A3 and promotion of cell migration. The mechanistic involvement of miR-210-3p in this pathway was confirmed by applying a specific antago-miR.

CONCLUSIONS

In sum, we unveiled a previously unknown NRP1-dependent paracrine signaling mechanism, mediated by the loading of pro-angiogenic miR-210-3p in exosomes released by cancer cells, which underscores the relevance of NRP1 in controlling the tumor microenvironment.

Regulatory Immune Cell-derived Exosomes: Modes of Action and Therapeutic Potential in Transplantation

Reduced dependence on antirejection agents, improved long-term allograft survival, and induction of operational tolerance remain major unmet needs in organ transplantation due to the limitations of current immunosuppressive therapies. To address this challenge, investigators are exploring the therapeutic potential of adoptively transferred host- or donor-derived regulatory immune cells. Extracellular vesicles of endosomal origin (exosomes) secreted by these cells seem to be important contributors to their immunoregulatory properties. Twenty years ago, it was first reported that donor-derived exosomes could extend the survival of transplanted organs in rodents. Recent studies have revealed that regulatory immune cells, such as regulatory myeloid cells (dendritic cells, macrophages, or myeloid-derived suppressor cells), regulatory T cells, or mesenchymal stem/stromal cells can suppress graft rejection via exosomes that express a cargo of immunosuppressive molecules. These include cell surface molecules that interact with adaptive immune cell receptors, immunoregulatory enzymes, and micro- and long noncoding RNAs that can regulate inflammatory gene expression via posttranscriptional changes and promote tolerance through promotion of regulatory T cells. This overview analyzes the diverse molecules and mechanisms that enable regulatory immune cell-derived exosomes to modulate alloimmunity and promote experimental transplant tolerance. We also discuss the potential benefits and limitations of their application as therapeutic entities in organ transplantation.

Harnessing extracellular vesicle heterogeneity for diagnostic and therapeutic applications

Extracellular vesicles (EVs) are diverse nanoparticles with large heterogeneity in size and molecular composition. Although this heterogeneity provides high diagnostic value for liquid biopsy and confers many exploitable functions for therapeutic applications in cancer detection, wound healing and neurodegenerative and cardiovascular diseases, it has also impeded their clinical translation-hence heterogeneity acts as a double-edged sword. Here we review the impact of subpopulation heterogeneity on EV function and identify key cornerstones for addressing heterogeneity in the context of modern analytical platforms with single-particle resolution. We outline concrete steps towards the identification of key active biomolecules that determine EV mechanisms of action across different EV subtypes. We describe how such knowledge could accelerate EV-based therapies and engineering approaches for mimetic artificial nanovesicle formulations. This approach blunts one edge of the sword, leaving only a single razor-sharp edge on which EV heterogeneity can be exploited for therapeutic applications across many diseases.

Extracellular vesicles for delivering therapeutic agents in ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is marked by the restriction and subsequent restoration of blood supply to an organ. This process can exacerbate the initial tissue damage, leading to further disorders, disability, and even death. Extracellular vesicles (EVs) are crucial in cell communication by releasing cargo that regulates the physiological state of recipient cells. The development of EVs presents a novel avenue for delivering therapeutic agents in I/R therapy. The therapeutic potential of EVs derived from stem cells, endothelial cells, and plasma in I/R injury has been actively investigated. Therefore, this review aims to provide an overview of the pathological process of I/R injury and the biophysical properties of EVs. We noted that EVs serve as nontoxic, flexible, and multifunctional carriers for delivering therapeutic agents capable of intervening in I/R injury progression. The therapeutic efficacy of EVs can be enhanced through various engineering strategies. Improving the tropism of EVs via surface modification and modulating their contents via preconditioning are widely investigated in preclinical studies. Finally, we summarize the challenges in the production and delivery of EV-based therapy in I/R injury and discuss how it can advance. This review will encourage further exploration in developing efficient EV-based delivery systems for I/R treatment.

Enhanced enrichment of extracellular vesicles for laboratory and clinical research from drop-sized blood samples

In the realm of biomedical advancement, extracellular vesicles (EVs) are revolutionizing our capacity to diagnose, monitor, and predict disease progression. However, the comprehensive exploration and clinical application of EVs face significant limitations due to the current isolation techniques. The size exclusion chromatography, commercial precipitation reagents, and ultracentrifugation are frequently employed, necessitating skilled operators and entailing challenges related to consistency, reproducibility, quality, and yields. Notably, the formidable challenge of extracellular vesicle isolation persists when dealing with clinical samples of limited availability. This study addresses these challenges by aiming to devise a rapid, user-friendly, and high-recovery EVs isolation technique tailored for blood samples. The NTI-EXO precipitation method demonstrated a 5-fold increase in the recovery of serum EVs compared to current methodologies. Importantly, we illustrate that a mere two drops of blood (∼100 µL) suffice for the recovery of enriched EVs. The integrity and quality of these isolated EVs were rigorously assessed for the size, purity, and contaminants. This method was validated through the successful isolation of EVs from organ transplant recipients to detect disease-specific exosomal markers, including LKB1, SARS-CoV-2 spike protein, and PD-L1. In conclusion, NTI-EXO method can be used for small clinical samples, thereby advancing discoveries in the EV-centric domain and propelling the frontiers of biomedical research and clinical applications.

Exosomes derived from cord blood Treg cells promote diabetic wound healing by targeting monocytes

Chronic nonhealing diabetic wounds are a critical clinical challenge. Regulatory T cells (Tregs) are immunosuppressive modulators affecting wound healing progression by controlling the inflammatory response. The current study attempted to investigate whether the exosomes derived from cord blood (CB) Tregs can accelerate the healing process. Exosomes were isolated from CB-Treg cultures using ultracentrifugation and validated with different specific markers of exosomes. The purified CB-Treg-derived exosomes were co-cultured with peripheral blood mononuclear cells (PBMCs) and CD14+ monocytes. The migration-promoting effect of CB-Treg-derived exosomes on fibroblasts and endothelial cells was investigated. We used thermosensitive Pluronic F-127 hydrogel (PF-127) loaded with CB-Treg-derived exosomes in a diabetic wound healing mouse model. CB-Treg-derived exosomes with 30-120 nm diameters revealed exosome-specific markers, such as TSG101, Alix, and CD63. CB-Treg-derived exosomes were mainly bound to the monocytes when co-cultured with PBMCs, and promoted monocyte polarization to the anti-inflammatory phenotype (M2) in vitro. CB-Treg-derived exosomes enhanced the migration of endothelial cells and fibroblasts. Furthermore, CB-Treg-derived exosomes treatment accelerated wound healing by downregulating inflammatory factor levels and upregulating the M2 macrophage ratio in vivo. Our findings indicated that CB-Treg-derived exosomes could be a promising cell-free therapeutic strategy for diabetic wound healing, partly by targeting monocytes.

Treg-Derived Extracellular Vesicles: Roles in Diseases and Theranostics

Regulatory T cells (Tregs), a subset of CD4+ T cells, are indispensable in maintaining immune self-tolerance and have been utilized in various diseases. Treg-derived extracellular vesicles (Treg-EVs) have been discovered to play an important role in the mechanism of Treg functions. As cell-derived membranous particles, EVs carry multiple bioactive substances that possess tremendous potential for theranostics. Treg-EVs are involved in numerous physiological and pathological processes, carrying proteins and miRNAs inherited from the parental cells. To comprehensively understand the function of Treg-EVs, here we reviewed the classification of Treg-EVs, the active molecules in Treg-EVs, their various applications in diseases, and the existing challenges for Treg-EVs based theranostics. This Review aims to clarify the feasibility and potential of Treg-EVs in diseases and theranostics, facilitating further research and application of Treg-EVs.

Extracellular vesicles: Messengers of allergic immune responses and novel therapeutic strategy

Extracellular vesicles (EVs) are nanosized particles released by nearly every cell type across all kingdoms of life. As a result, EVs are ubiquitously present in various human body fluids. Composed of a lipid bilayer, EVs encapsulate proteins, nucleic acids, and metabolites, thus playing a crucial role in immunity, for example, by enabling intercellular communication. More recently, there has been increasing evidence that EVs can also act as key regulators of allergic immune responses. Their ability to facilitate cell-to-cell contact and to transport a variety of different biomolecules enables active modulation of both innate and adaptive immune processes associated with allergic reactions. A comprehensive understanding of the intricate mechanisms underlying the interactions among allergens, immune cells, and EVs is imperative to develop innovative strategies for controlling allergic responses. This review highlights the recent roles of host cell- and bacteria-derived EVs in allergic diseases, presenting experimental and clinical evidence that underscores their significance. Additionally, the therapeutic potential of EVs in allergy management is outlined, along with the challenges associated with targeted delivery and cargo stability for clinical use. Optimization of EV composition and targeting strategies holds promise for advancing translational applications and establishing EVs as biomarkers or safe therapeutics for assessing allergic reactions. For these reasons, EVs represent a promising avenue for advancing both our understanding and management of allergic immune processes.

Sumoylation in astrocytes induces changes in the proteome of the derived small extracellular vesicles which change protein synthesis and dendrite morphology in target neurons

Emerging evidence highlights the relevance of the protein post-translational modification by SUMO (Small Ubiquitin-like Modifier) in the central nervous system for modulating cognition and plasticity in health and disease. In these processes, astrocyte-to-neuron crosstalk mediated by extracellular vesicles (EVs) plays a yet poorly understood role. Small EVs (sEVs), including microvesicles and exosomes, contain a molecular cargo of lipids, proteins, and nucleic acids that define their biological effect on target cells. Here, we investigated whether SUMOylation globally impacts the sEV protein cargo. For this, sEVs were isolated from primary cultures of astrocytes by ultracentrifugation or using a commercial sEV isolation kit. SUMO levels were regulated: 1) via plasmids that over-express SUMO, or 2) via experimental conditions that increase SUMOylation, i.e., by using the stress hormone corticosterone, or 3) via the SUMOylation inhibitor 2-D08 (2',3',4'-trihydroxy-flavone, 2-(2,3,4-Trihydroxyphenyl)-4H-1-Benzopyran-4-one). Corticosterone and 2-D08 had opposing effects on the number of sEVs and on their protein cargo. Proteomic analysis showed that increased SUMOylation in corticosterone-treated or plasmid-transfected astrocytes increased the presence of proteins related to cell division, transcription, and protein translation in the derived sEVs. When sEVs derived from corticosterone-treated astrocytes were transferred to neurons to assess their impact on protein synthesis using the fluorescence non-canonical amino acid tagging assay (FUNCAT), we detected an increase in protein synthesis, while sEVs from 2-D08-treated astrocytes had no effect. Our results show that SUMO conjugation plays an important role in the modulation of the proteome of astrocyte-derived sEVs with a potential functional impact on neurons.

Exosomal miR-181d-5p Derived from Rapamycin-Conditioned MDSC Alleviated Allograft Rejection by Targeting KLF6

Immune rejection and side effects of long-term administration of immunosuppressants are the two major obstacles to allograft acceptance and tolerance. The immunosuppressive extracellular vesicles (EVs)-based approach has been proven to be effective in treating autoimmune/inflammatory disorders. Herein, the anti-rejection advantage of exosomes (Rapa-Exo) from rapamycin-conditioned myeloid-derived suppressor cells (MDSCs) over exosomes (Exo-Nor) from the untreated MDSCs is shown. The exosomal small RNA sequencing and loss-of-function assays reveal that the anti-rejection effect of Rapa-Exo functionally relies on miR-181d-5p. Through target prediction and double-luciferase reporter assay, Kruppel-like factor (KLF) 6 is identified as a direct target of miR-181d-5p. Finally, KLF6 knockdown markedly resolves inflammation and prolongs the survival of corneal allografts. Taken together, these findings support that Rapa-Exo executes an anti-rejection effect, highlighting the immunosuppressive EVs-based treatment as a promising approach in organ transplantation.

Extracellular Vesicles from Immune Cells: A Biomedical Perspective

Research on the role of extracellular vesicles (sEV) in physiology has demonstrated their undoubted importance in processes such as the transportation of molecules with significance for cell metabolism, cell communication, and the regulation of mechanisms such as cell differentiation, inflammation, and immunity. Although the role of EVs in the immune response is actively investigated, there is little literature revising, in a comprehensive manner, the role of small EVs produced by immune cells. Here, we present a review of studies reporting the release of sEV by different types of leukocytes and the implications of such observations on cellular homeostasis. We also discuss the function of immune cell-derived sEV and their relationship with pathological states, highlighting their potential application in the biomedical field.

3D Printing of Microenvironment-Specific Bioinspired and Exosome-Reinforced Hydrogel Scaffolds for Efficient Cartilage and Subchondral Bone Regeneration

In clinical practice, repairing osteochondral defects presents a challenge due to the varying biological properties of articular cartilages and subchondral bones. Thus, elucidating how spatial microenvironment-specific biomimetic scaffolds can be used to simultaneously regenerate osteochondral tissue is an important research topic. Herein, a novel bioinspired double-network hydrogel scaffold produced via 3D printing with tissue-specific decellularized extracellular matrix (dECM) and human adipose mesenchymal stem cell (MSC)-derived exosomes is described. The bionic hydrogel scaffolds promote rat bone marrow MSC attachment, spread, migration, proliferation, and chondrogenic and osteogenic differentiation in vitro, as determined based on the sustained release of bioactive exosomes. Furthermore, the 3D-printed microenvironment-specific heterogeneous bilayer scaffolds efficiently accelerate the simultaneous regeneration of cartilage and subchondral bone tissues in a rat preclinical model. In conclusion, 3D dECM-based microenvironment-specific biomimetics encapsulated with bioactive exosomes can serve as a novel cell-free recipe for stem cell therapy when treating injured or degenerative joints. This strategy provides a promising platform for complex zonal tissue regeneration whilst holding attractive clinical translation potential.

Tregs in transplantation tolerance: role and therapeutic potential

CD4+ Foxp3+ regulatory T cells (Tregs) are indispensable for preventing autoimmunity, and they play a role in cancer and transplantation settings by restraining immune responses. In this review, we describe evidence for the importance of Tregs in the induction versus maintenance of transplantation tolerance, discussing insights into mechanisms of Treg control of the alloimmune response. Further, we address the therapeutic potential of Tregs as a clinical intervention after transplantation, highlighting engineered CAR-Tregs as well as expansion of donor and host Tregs.

A Review of Extracellular Vesicles in COVID-19 Diagnosis, Treatment, and Prevention

The 2019 novel coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is ongoing, and has necessitated scientific efforts in disease diagnosis, treatment, and prevention. Interestingly, extracellular vesicles (EVs) have been crucial in these developments. EVs are a collection of various nanovesicles which are delimited by a lipid bilayer. They are enriched in proteins, nucleic acids, lipids, and metabolites, and naturally released from different cells. Their natural material transport properties, inherent long-term recycling ability, excellent biocompatibility, editable targeting, and inheritance of parental cell properties make EVs one of the most promising next-generation drug delivery nanocarriers and active biologics. During the COVID-19 pandemic, many efforts have been made to exploit the payload of natural EVs for the treatment of COVID-19. Furthermore, strategies that use engineered EVs to manufacture vaccines and neutralization traps have produced excellent efficacy in animal experiments and clinical trials. Here, the recent literature on the application of EVs in COVID-19 diagnosis, treatment, damage repair, and prevention is reviewed. And the therapeutic value, application strategies, safety, and biotoxicity in the production and clinical applications of EV agents for COVID-19 treatment, as well as inspiration for using EVs to block and eliminate novel viruses are discussed.

Dynamics of inflammatory cytokine expression in bovine endometrial cells exposed to cow blood plasma small extracellular vesicles (sEV) may reflect high fertility

Aberrant inflammation in the endometrium impairs reproduction and leads to poor fertility. Small extracellular vesicles (sEV) are nanoparticles 30-200 nm in-size and contain transferable bioactive molecules that reflect the parent cell. Holstein-Friesian dairy cows with divergent genetic merit, high- (n = 10) and low-fertile (n = 10), were identified based on fertility breeding value (FBV), cow ovulation synchronization and postpartum anovulatory intervals (PPAI). In this study, we evaluated the effects of sEVs enriched from plasma of high-fertile (HF-EXO) and low-fertile (LF-EXO) dairy cows on inflammatory mediator expression by bovine endometrial epithelial (bEEL) and stromal (bCSC) cells. Exposure to HF-EXO in bCSC and bEEL cells yielded lower expression of PTGS1 and PTGS2 compared to the control. In bCSC cells exposed to HF-EXO, pro-inflammatory cytokine IL1-α was downregulated compared to the untreated control, IL-12α and IL-8 were downregulated compared to the LF-EXO treatment. Our findings demonstrate that sEVs interact with both endometrial epithelial and stromal cells to initiate differential gene expression, specifically genes relate to inflammation. Therefore, even subtle changes on the inflammatory gene cascade in the endometrium via sEV may affect reproductive performance and/or outcomes. Further, sEV from high-fertile animals acts in a unique direction to deactivate prostaglandin synthases in both bCSC and bEEL cells and deactivate pro-inflammatory cytokines in the endometrial stroma. The results suggest that circulating sEV may serve as a potential biomarker of fertility.

Roles of Regulatory T Cell-Derived Extracellular Vesicles in Human Diseases

Regulatory T (Treg) cells play crucial roles in maintaining immune self-tolerance and immune homeostasis, and closely associated with many human diseases. Recently, Treg cells-derived extracellular vesicles (Treg-EVs) have been demonstrated as a novel cell-contact independent inhibitory mechanism of Treg cells. Treg-EVs contain many specific biological molecules, which are delivered to target cells and modulate immune responses by inhibiting T cell proliferation, inducing T cell apoptosis, and changing the cytokine expression profiles of target cells. The abnormal quantity or function of Treg-EVs is associated with several types of human diseases or conditions, such as transplant rejection, inflammatory diseases, autoimmune diseases, and cancers. Treg-EVs are promising novel potential targets for disease diagnosis, therapy, and drug transport. Moreover, Treg-EVs possess distinct advantages over Treg cell-based immunotherapies. However, the therapeutic potential of Treg-EVs is limited by some factors, such as the standardized protocol for isolation and purification, large scale production, and drug loading efficiency. In this review, we systematically describe the structure, components, functions, and basic mechanisms of action of Treg-EVs and discuss the emerging roles in pathogenesis and the potential application of Treg-EVs in human diseases.

Preventing type 1 diabetes in late-stage pre-diabetic NOD mice with insulin: A central role for alum as adjuvant

BACKGROUND

Restoration of immune tolerance to disease-relevant antigens is an appealing approach to prevent or arrest an organ-specific autoimmune disease like type 1 diabetes (T1D). Numerous studies have identified insulin as a key antigen of interest to use in such strategies, but to date, the success of these interventions in humans has been inconsistent. The efficacy of antigen-specific immunotherapy may be enhanced by optimising the dose, timing, and route of administration, and perhaps by the inclusion of adjuvants like alum. The aim of our study was to evaluate the effect of an insulin peptide vaccine formulated with alum to prevent T1D development in female non-obese diabetic (NOD) mice when administered during late-stage pre-diabetes.

METHODS

Starting at 10 weeks of age, female NOD mice received four weekly subcutaneous injections of an insulin B:8-24 (InsB:8-24) peptide with (Ins+alum) or without Imject^® alum (Ins) as adjuvant. Diabetes incidence was assessed for up to 30 weeks of age. Insulin autoantibodies and C-peptide concentrations were measured in plasma and flow cytometric analysis was performed on pancreatic-draining lymph nodes (PLN) and pancreas using an InsB:12-20-reactive tetramer.

RESULTS

InsB:8-24 peptide formulated in alum reduced diabetes incidence (39%), compared to mice receiving the InsB:8-24 peptide without alum (71%, P < 0.05), mice receiving alum alone (76%, P < 0.01), or mice left untreated (70%, P < 0.01). This was accompanied by reduced insulitis severity, and preservation of C-peptide. Ins+alum was associated with reduced frequencies of pathogenic effector memory CD4⁺ and CD8⁺ T cells in the pancreas and increased frequencies of insulin-reactive FoxP3⁺ Tregs in the PLN. Of interest, insulin-reactive Tregs were enriched amongst populations of Tregs expressing markers indicative of stable FoxP3 expression and enhanced suppressive function.

CONCLUSION

An InsB:8-24 peptide vaccine prevented the onset of T1D in late-stage pre-diabetic NOD mice, but only when formulated in alum. These findings support the use of alum as adjuvant to optimise the efficacy of antigen-specific immunotherapy in future trials.