Exosomes from high glucose-treated macrophages activate macrophages andinduce inflammatory responses via NF-κB signaling pathway in vitro and in vivo

Macrophage exosomes mediate palmitic acid-induced metainflammation by transferring miR-3064-5p to target IκBα and activate NF-κB signaling

INTRODUCTION

High palmitic acid (PA) levels trigger metainflammation, facilitating the onset and progression of chronic metabolic diseases. Recently, exosomes were identified as new inflammation mediators. However, the mechanism by which macrophage exosomes mediate PA-induced inflammation remains unclear.

OBJECTIVES

To explore how PA induces metainflammation through macrophage exosomes.

METHODS

Exosomes secreted by RAW264.7 mouse macrophages stimulated with PA (ExosPA) or not (Exos) were prepared by ultracentrifugation. The differential miRNAs between ExosPA and Exos were identified by high-throughput sequencing, and their targeted mRNAs and proteins were bioinformatically analyzed and verified by qPCR and western blot. Mouse macrophages and metabolic cells (AML-12 hepatocytes, C2C12 myocytes or 3T3-L1 adipocytes) were treated with ExosPA or Exos. The verified miRNAs and its targeted molecules related to inflammation were analyzed in recipient cells. Furthers, exosomes were prepared from primary peritoneal macrophages isolated from AIN93G diet-fed (Control PM-Exos) or HPD-fed (PA PM-Exos) mice. Control or PA PM-Exos were then tail vein injected (30 μg) into mice (n = 10), once a week for 2 weeks. The verified miRNA and its targets in blood, blood exosomes, and metabolic tissues were detected. Finally, measured the levels of miRNA, inflammatory factors, and fatty acids in the blood of 20 obese/overweight individuals and 20 healthy individuals.

RESULTS

ExoPA activate NF-κB signaling and enhance inflammatory enzyme/cytokine production in macrophages and metabolic cells. ExoPA enrich miR-3064-5p and target to inhibit IκBα as verified by exosome inhibitors and miR-3064-5p mimics and inhibitors. HPD elevates exosomal miR-3064-5p, macrophage exosomal miR-3064-5p, and inflammatory cytokine levels in mice circulation. PA PM-Exos from HPD-fed mice triggered inflammation in the circulation and metabolic tissues/organs of chow diet-fed mice. Overweight/obese individuals exhibit increased levels of circulating palmitoleic acid, exosomal miR-3064-5p, and high-sensitivity C-reactive proteins.

CONCLUSIONS

Macrophage exosomes transferring miR-3064-5p to target IκBα and activate NF-κB signaling in metabolic cells is a mechanism of PA-induced metainflammation.

The role and therapeutic potential of macrophages in the pathogenesis of diabetic cardiomyopathy

This review provides a comprehensive analysis of the critical role played by macrophages and their underlying mechanisms in the progression of diabetic cardiomyopathy (DCM). It begins by discussing the origins and diverse subtypes of macrophages, elucidating their spatial distribution and modes of intercellular communication, thereby emphasizing their significance in the pathogenesis of DCM. The review then delves into the intricate relationship between macrophages and the onset of DCM, particularly focusing on the epigenetic regulatory mechanisms employed by macrophages in the context of DCM condition. Additionally, the review discusses various therapeutic strategies aimed at targeting macrophages to manage DCM. It specifically highlights the potential of natural food components in alleviating diabetic microvascular complications and examines the modulatory effects of existing hypoglycemic drugs on macrophage activity. These findings, summarized in this review, not only provide fresh insights into the role of macrophages in diabetic microvascular complications but also offer valuable guidance for future therapeutic research and interventions in this field.

Renal Tissue-Derived Exosomal miRNA-34a in Diabetic Nephropathy Induces Renal Tubular Cell Fibrosis by Promoting the Polarization of M1 Macrophages

Background

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease, and the activation and infiltration of phagocytes are critical steps of DN. This study aimed to explore the mechanism of exosomes in macrophages and diabetes nephropathy and the role of miRNA-34a, which might provide a new path for treating DN.

Materials and Methods

The DN model was established, and the success of the model establishment was confirmed by detecting general indicators, HE staining, and immunohistochemistry. Electron microscopy and NanoSight Tracking Analysis (NTA) were used to see the morphology and size of exosomes. MiRNA-34a inhibitor, miRNA-34a mimics, pc-PPARGC1A, and controls were transfected in macrophages with or without kidney exosomal. A dual-luciferase reporter gene experiment verifies the targeting relationship between miRNA-34a and PPARGC1A. After exosomal culture, macrophages are co-cultured with normal renal tubular cells to detect renal tubular cell fibrosis. Q-PCR and western blot were undertaken to detect related RNA and proteins.

Results

An animal model of diabetic nephropathy was successfully constructed. Macrophages could phagocytose exosomes. After ingesting model exosomes, M1 macrophages were activated, while M2 macrophages were weakened, indicating the model mice's kidney exosomes caused the polarization. MiRNA-34a inhibitor increased PPARGC1A expression. MiRNA-34a expressed higher in diabetic nephropathy Model-Exo. MiRNA-34a negatively regulated PPARGC1A. PPARGC1A rescued macrophage polarization and renal tubular cell fibrosis.

Conclusion

Exosomal miRNA-34a of tubular epithelial cells promoted M1 macrophage activation in diabetic nephropathy via negatively regulating PPARGC1A expression, which may provide a new direction for further exploration of DN treatment.

Integrating network pharmacology, molecular docking and simulation approaches with machine learning reveals the multi-target pharmacological mechanism of Berberis integerrima against diabetic nephropathy

Diabetic nephropathy (DN) is one of the most feared complications of diabetes and key cause of end-stage renal disease (ESRD). Berberis integerrima has been widely used to treat diabetic complications, but exact molecular mechanism is yet to be discovered. Data on active ingredients of B. integerrima and target genes of both diabetic nephropathy and B.integerrima were obtained from public databases. Common results between B. integerrima and DN targets were used to create protein-protein interaction (PPI) network using STRING database and exported to Cytoscape software for the selection of hub genes based on degree of connectivity. Future, PPI network between constituents and overlapping targets was created using Cytoscape to investigate the network pharmacological effects of B. integerrima on DN. KEGG pathway analysis of core genes exposed their involvement in excess glucose-activated signaling pathway. Then, expression of core genes was validated through machine learning classifiers. Finally, PyRx and AMBER18 software was used for molecular docking and simulation. We found that Armepavine, Berberine, Glaucine, Magnoflorine, Reticuline, Quercetin inhibits the growth of diabetic nephropathy by affecting ICAM1, PRKCB, IKBKB, KDR, ALOX5, VCAM1, SYK, TBXA2R, LCK, and F3 genes. Machine learning revealed SYK and PRKCB as potential genes that could use as diagnostic biomarkers against DN. Furthermore, docking and simulation analysis showed the binding affinity and stability of the active compound with target genes. Our study revealed that B. integerrima has preventive effect on DN by acting on glucose-activated signaling pathways. However, experimental studies are needed to reveal biosafety profiles of B. integerrima in DN.Communicated by Ramaswamy H. Sarma.

Macrophage-Derived Exosomes as Advanced Therapeutics for Inflammation: Current Progress and Future Perspectives

The development of numerous diseases is significantly influenced by inflammation. Macrophage-derived exosomes (M-Exos) play a role in controlling inflammatory reactions in various conditions, including chronic inflammatory pain, hypertension, and diabetes. However, the specific targets and roles of M-Exos in regulating inflammation in diseases remain largely unknown. This review summarizes current knowledge on M-Exos biogenesis and provides updated information on M-Exos' biological function in inflammation modulation. Furthermore, this review highlights the functionalization and engineering strategies of M-Exos, while providing an overview of cutting-edge approaches to engineering M-Exos and advancements in their application as therapeutics for inflammation modulation. Finally, multiple engineering strategies and mechanisms are presented in this review along with their perspectives and challenges, and the potential contribution that M-Exos may have in diseases through the modulation of inflammation is discussed.

Exploring the role of urinary extracellular vesicles in kidney physiology, aging, and disease progression

Extracellular vesicles (EVs), membranous vesicles present in all body fluids, are considered important messengers, carrying their information over long distance and modulating the gene expression profile of recipient cells. EVs collected in urine (uEVs) are mainly originated from the apical part of urogenital tract, following the urine flow. Moreover, bacterial-derived EVs are present within urine and may reflect the composition of microbiota. Consolidated evidence has established the involvement of uEVs in renal physiology, being responsible for glomerular and tubular cross talk and among different tubular segments. uEVs may also be involved in other physiological functions such as modulation of innate immunity, coagulation, or metabolic activities. Furthermore, it has been recently remonstrated that age, sex, endurance excise, and lifestyle may influence uEV composition and release, modifying their cargo. On the other hand, uEVs appear modulators of different urogenital pathological conditions, triggering disease progression. uEVs sustain fibrosis and inflammation processes, both involved in acute and chronic kidney diseases, aging, and stone formation. The molecular signature of uEVs collected from diseased patients can be of interest for understanding kidney physiopathology and for identifying diagnostic and prognostic biomarkers.

Macrophage-derived exosomes promote activation of NLRP3 inflammasome and autophagy deficiency of mesangial cells in diabetic nephropathy

Dysfunction of mesangial cells plays a significant role in the glomerular lesions and is implicated in the pathophysiology of diabetic nephropathy (DN). Macrophages infiltration is the main pathological feature of DN, which can ultimately lead to renal inflammation. Recent studies suggest that the crosstalk between kidney resident cells and inflammatory cells influences the development of DN, and that controlling this crosstalk may help treat DN. Here, we found that DN mice appeared renal pathological damage, including dilation of mesangial matrix and significant infiltration of macrophages, accompanied by increased inflammatory response, NLRP3 inflammasome activation and autophagy deficiency. Additionally, mesangial cells internalized exosomes from high glucose (HG) treated macrophage, resulting the activation of inflammatory cytokines and NLRP3 inflammasome and deficiency of autophagy in vitro and in vivo. Moreover, C57BL/6 mice injected HG-stimulated macrophages-derived exosomes exhibited renal dysfunction and mesangial matrix expansion. Taken together, the present study demonstrated that mesangial cells responded to HG treated macrophage-derived exosomes by promoting the activation of NLRP3 inflammasome and autophagy deficiency, thereby participating in the development of DN.

Cardiovascular complications of diabetes: role of non-coding RNAs in the crosstalk between immune and cardiovascular systems

Diabetes mellitus, a group of metabolic disorders characterized by high levels of blood glucose caused by insulin defect or impairment, is a major risk factor for cardiovascular diseases and related mortality. Patients with diabetes experience a state of chronic or intermittent hyperglycemia resulting in damage to the vasculature, leading to micro- and macro-vascular diseases. These conditions are associated with low-grade chronic inflammation and accelerated atherosclerosis. Several classes of leukocytes have been implicated in diabetic cardiovascular impairment. Although the molecular pathways through which diabetes elicits an inflammatory response have attracted significant attention, how they contribute to altering cardiovascular homeostasis is still incompletely understood. In this respect, non-coding RNAs (ncRNAs) are a still largely under-investigated class of transcripts that may play a fundamental role. This review article gathers the current knowledge on the function of ncRNAs in the crosstalk between immune and cardiovascular cells in the context of diabetic complications, highlighting the influence of biological sex in such mechanisms and exploring the potential role of ncRNAs as biomarkers and targets for treatments. The discussion closes by offering an overview of the ncRNAs involved in the increased cardiovascular risk suffered by patients with diabetes facing Sars-CoV-2 infection.

Knowledge mapping of exosomes in metabolic diseases: a bibliometric analysis (2007-2022)

Background

Research on exosomes in metabolic diseases has been gaining attention, but a comprehensive and objective report on the current state of research is lacking. This study aimed to conduct a bibliometric analysis of publications on "exosomes in metabolic diseases" to analyze the current status and trends of research using visualization methods.

Methods

The web of science core collection was searched for publications on exosomes in metabolic diseases from 2007 to 2022. Three software packages, VOSviewer, CiteSpace, and R package "bibliometrix" were used for the bibliometric analysis.

Results

A total of 532 papers were analyzed, authored by 29,705 researchers from 46 countries/regions and 923 institutions, published in 310 academic journals. The number of publications related to exosomes in metabolic diseases is gradually increasing. China and the United States were the most productive countries, while Ciber Centro de Investigacion Biomedica en Red was the most active institution. The International Journal of Molecular Sciences published the most relevant studies, and Plos One received the most citations. Khalyfa, Abdelnaby published the most papers and Thery, C was the most cited. The ten most co-cited references were considered as the knowledge base. After analysis, the most common keywords were microRNAs, biomarkers, insulin resistance, expression, and obesity. Applying basic research related on exosomes in metabolic diseases to clinical diagnosis and treatment is a research hotspot and trend.

Conclusion

This study provides a comprehensive summary of research trends and developments in exosomes in metabolic diseases through bibliometrics. The information points out the research frontiers and hot directions in recent years and will provide a reference for researchers in this field.

Dapagliflozin Treatment Augments Bioactive Phosphatidylethanolamine Concentrations in Kidney Cortex Membrane Fractions of Hypertensive Diabetic db/db Mice and Alters the Density of Lipid Rafts in Mouse Proximal Tubule Cells

In addition to inhibiting renal glucose reabsorption and allowing for glucose excretion, the sodium/glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin may be efficacious in treating various comorbidities associated with type 2 diabetes mellitus (T2DM). The molecular mechanisms by which dapagliflozin exerts its beneficial effects are largely unknown. We hypothesized dapagliflozin treatment in the diabetic kidney alters plasma membrane lipid composition, suppresses extracellular vesicle (EV) release from kidney cells, and disrupts lipid rafts in proximal tubule cells. In order to test this hypothesis, we treated diabetic db/db mice with dapagliflozin (N = 8) or vehicle (N = 8) and performed mass spectrometry-based lipidomics to investigate changes in the concentrations of membrane lipids in the kidney cortex. In addition, we isolated urinary EVs (uEVs) from urine samples collected during the active phase and the inactive phase of the mice and then probed for changes in membrane proteins enriched in the EVs. Multiple triacylglycerols (TAGs) were enriched in the kidney cortex membrane fractions of vehicle-treated diabetic db/db mice, while the levels of multiple phosphatidylethanolamines were significantly higher in similar mice treated with dapagliflozin. EV concentration and size were lesser in the urine samples collected during the inactive phase of dapagliflozin-treated diabetic mice. In cultured mouse proximal tubule cells treated with dapagliflozin, the lipid raft protein caveolin-1 shifted from less dense fractions to more dense sucrose density gradient fractions. Taken together, these results suggest dapagliflozin may regulate lipid-mediated signal transduction in the diabetic kidney.

Roles and crosstalks of macrophages in diabetic nephropathy

Diabetic nephropathy (DN) is the most common chronic kidney disease. Accumulation of glucose and metabolites activates resident macrophages in kidneys. Resident macrophages play diverse roles on diabetic kidney injuries by releasing cytokines/chemokines, recruiting peripheral monocytes/macrophages, enhancing renal cell injuries (podocytes, mesangial cells, endothelial cells and tubular epithelial cells), and macrophage-myofibroblast transition. The differentiation and cross-talks of macrophages ultimately result renal inflammation and fibrosis in DN. Emerging evidence shows that targeting macrophages by suppressing macrophage activation/transition, and macrophages-cell interactions may be a promising approach to attenuate DN. In the review, we summarized the diverse roles of macrophages and the cross-talks to other cells in DN, and highlighted the therapeutic potentials by targeting macrophages.

Exosomal miR-7002-5p derived from highglucose-induced macrophages suppresses autophagy in tubular epithelial cells by targeting Atg9b

Macrophage infiltration plays an important role in the progression of diabetic nephropathy (DN). Previously, we demonstrated that highglucose-stimulated macrophage-derived exosomes (HG-exo) induces proliferation and extracellular matrix accumulation in glomerular mesangial cells, but its effect on tubular cells is unclear. This study aimed to explore the role of HG-exo on renal tubular injury in DN. The results show that HG-exo could induce dysfunction, autophagy inhibition, and inflammation in mouse tubular epithelial cell (mTEC) and C57 mouse kidney. Moreover, miR-7002-5p was differentially expressed in HG-exo based on miRNAs sequencing and bioinformatics analysis. A dual-luciferase reporter assay confirmed that Atg9b was the direct target gene of miR-7002-5p. Further experimentation showed that miR-7002-5p inhibition in vivo and vitro reserves HG-exo effects. These results demonstrated that HG-exo carries excessive miR-7002-5p and inhibits autophagy through targeting Atg9b; this process then induces renal tubular dysfunction and inflammation. In conclusion, our study clarifies the important role of macrophage-derived exosomes in DN and is expected to provide new insight on DN prevention and treatment.

GABA alleviates high glucose-induced podocyte injury through dynamically altering the expression of macrophage M1/M2-derived exosomal miR-21a-5p/miR-25-3p

Podocyte injury is the main clinical pathological feature of diabetic kidney disease (DKD). The studies showed that DKD is associated with the polarization of macrophages to different types (M1 or M2) and the inflammatory processes which they mediate. It is a hot research topic in the treatment of DKD that find and intervene genes which related to M1/M2 phenotype. The potential anti-inflammatory effects on γ-aminobutyric acid (GABA) have been shown to be related to the regulation of the polarization direction of macrophages. However, it remains unknown that whether GABA can alleviate DKD. The purpose of current study was to explore the role of GABA involved in high glucose (HG)-induced podocyte injury by regulating the M1/M2 phenotype. In the beginning, our results revealed that exogenous GABA treatment altered the direction of HG-induced macrophage polarization and suppressed the inflammatory response. Subsequently, macrophage-derived exosomes under HG treatment were found to be involved in aggravating HG-induced podocyte injury (decreased the proliferation capacity and increased apoptosis rate of cells). Furthermore, GABA treatment blocked the promotion of macrophage-mediated exosomes on podocyte injury under HG. Then, we found that GABA alleviated the promoting effect of macrophages on podocyte injury by regulating the expression of exosomal miR-21a-5p/miR-25-3p which mediated by macrophages. Finally, it was elucidated that Tnpo1/ATXN3 were the targets of miR-21a-5p/miR-25-3p, respectively, and mediated the promotion of podocyte injury by macrophage-derived exosomes under HG. This research suggested that GABA alleviated podocyte injury by reversing the M1/M2 polarization direction of macrophages under HG and regulating the miR-21a-5p-Tnpo1/miR-25-3p-ATXN3 signal axis of macrophage-derived exosomes.

The Immuno-Modulation Effect of Macrophage-Derived Extracellular Vesicles in Chronic Inflammatory Diseases

As natural nanocarriers and intercellular messengers, extracellular vesicles (EVs) control communication among cells. Under physiological and pathological conditions, EVs deliver generic information including proteins and nucleic acids to recipient cells and exert regulatory effects. Macrophages help mediate immune responses, and macrophage-derived EVs may play immunomodulatory roles in the progression of chronic inflammatory diseases. Furthermore, EVs derived from various macrophage phenotypes have different biological functions. In this review, we describe the pathophysiological significance of macrophage-derived extracellular vesicles in the development of chronic inflammatory diseases, including diabetes, cancer, cardiovascular disease, pulmonary disease, and gastrointestinal disease, and the potential applications of these EVs.

Astragalus mongholicus Bunge and Panax notoginseng formula (A&P) improves renal mesangial cell damage in diabetic nephropathy by inhibiting the inflammatory response of infiltrated macrophages

BACKGROUND

Diabetic nephropathy (DN) is one of the main causes of end-stage renal disease with scantly effective treatment. Numerous evidences indicated that macrophages play an important role in the occurrence and pathogenesis of DN by secreting inflammatory cytokines. Mincle is mainly expressed in macrophages and promotes kidney inflammation and damage of acute kidney injury. However, the role of Mincle in DN is unclear. In this study, we aim to investigate the effect of Mincle-related macrophage inflammation on DN, and whether it can be identified as the therapeutic target for Astragalus mongholicus Bunge and Panax notoginseng Formula (A&P), a widely used Chinese herbal decoction for DN treatment.

METHODS

In vivo experiments high-fat and high-sugar diet and streptozotocin was used to establish a diabetic nephropathy model, while in vitro experiments inflammation model was induced by high-glucose in mouse Bone Marrow-Derived Macrophages (BMDM) cells and mouse mesangial (MES) cells. Kidney pathological staining is used to detect kidney tissue damage and inflammation, Western blotting, Real-time PCR and ELISA are performed to detect Mincle signaling pathway related proteins and inflammatory cytokines.

RESULTS

Mincle was mainly expressed in infiltrated macrophage of DN kidney, and was significant decreased after A&P administration. The in vitro experiments also proved that A&P effectively down-regulated the expression of Mincle in macrophage stimulated by high glucose. Meanwhile, the data demonstrated that A&P can reduce the activation of NFκB, and the expression and secretion of inflammatory cytokines in DN kidney or BMDM cells. Notably, we set up a co-culture system to conform that BMDM cells can aggravate the inflammatory response of mesangial (MES) cells under high glucose stimulation. Furthermore, we found that the anti-injury role of A&P in MES cells was dependent on inhibition of the Mincle in macrophage.

CONCLUSION

In summary, our study found that A&P is effective in reducing renal pathological damage and improving renal function and inflammation in diabetic nephropathy by a mechanism mainly related to the inhibition of the Mincle/Card9/NFκB signaling pathway.

Anti-inflammatory activity of peptides derived from millet bran in vitro and in vivo

Various food-derived bioactive peptides have been found with potential anti-inflammatory effects. Millet bran peptide is a food-derived bioactive peptide extracted from millet bran, a by-product of millet processing. In this...

Exosomes: Advances, development and potential therapeutic strategies in diabetic nephropathy

Exosomes, a major type of extracellular vesicles (EVs), are nanoscale vesicles excreted by almost all cell types via invagination of the endosomal membrane pathway. Exosomes play a crucial role in the mediation of intercellular communication both in health and disease, which can be ascribed to their capacity to be transported to neighboring or distant cells, thus regulating the biological function of recipient cells through cargos such as DNA, mRNA, proteins and microRNA. Diabetic nephropathy (DN) is a serious microvascular complication associated with diabetes mellitus as well as a significant cause of end-stage renal disease worldwide, which has resulted in a substantial economic burden on individuals and society. However, despite extensive efforts, therapeutic approaches that prevent the progression of DN do not exist, which implies new approaches are required. An increasing number of studies suggest that exosomes are involved in the pathophysiological processes associated with DN, which may potentially provide novel biomarkers and therapeutic targets for DN. Hence, this review summarizes recent advances involving exosome mechanisms in DN and their potential as biomarkers and therapeutic targets.

Increased airway epithelial cell-derived exosomes activate macrophage-mediated allergic inflammation via CD100 shedding

Airway epithelial cells (AECs) participate in allergic airway inflammation by producing mediators in response to allergen stimulation. Whether ovalbumin (OVA) challenge promotes exosome release from AECs (OVA‐challenged AEC‐derived exosomes (OAEs)), thereby affecting airway inflammation, as well as the underlying mechanisms, is unknown. Our study showed that AECs released an increased number of exosomes after OVA challenge, and the expression of Plexin B2 (PLXNB2; a natural CD100 ligand) was increased by a massive 85.7‐fold in OAEs than in PBS‐treated AEC‐derived exosomes (PAEs). CD100⁺F4/80⁺ macrophages engulfed OAEs to trigger the transcription of pro‐inflammatory chemokines and cytokines. Plxnb2 transcripts increased in asthmatic lungs, and similarly, PLXNB2 protein was highly enriched in exosomes purified from asthmatic bronchoalveolar lavage (BAL) fluid. Furthermore, aspiration of PLXNB2 or OAEs increased the recruitment of lung neutrophils, monocytes, eosinophils and dendritic cells in OVA‐challenged mice. Mechanistically, OAE aspiration enhanced the cleavage of CD100 by MMP14, which manifested as an increase in the soluble CD100 (sCD100) level in BAL fluid and lung homogenates. Knockdown of Mmp14 in macrophages prevented the cleavage of CD100 and reduced Ccl2, Ccl5 and Cxcl2 transcription. These data indicate that PLXNB2‐containing OAEs aggravate airway asthmatic inflammation via cleavage of CD100 by MMP14, suggesting potential therapeutic targets of OAE‐mediated asthma exacerbations.

Exosomes from mesenchymal stem cells expressing microribonucleic acid-125b inhibit the progression of diabetic nephropathy via the tumour necrosis factor receptor-associated factor 6/Akt axis

Diabetic nephropathy (DN) seriously threatens the health of patients with diabetes. Moreover, it has been reported that mesenchymal stem cell (MSC)-derived exosomal miRNAs can modulate the progression of multiple diseases, including DN. It has been suggested that miR-125b is involved in DN. However, the biological functions of exosomal miRNAs, especially miR-125b, in DN are still unclear. To establish a DN model in vitro, we used a model of human embryonic kidney epithelial cells (HKCs) injury induced by high glucose (HG). Then, miR-125b was delivered to the model cells in vitro via MSC-derived exosomes (MSC-Exos), and the effect of exosomal miR-125b on HKCs apoptosis was evaluated by flow cytometry. qRT-PCR or western blotting was performed to measure miR-125b or tumour necrosis factor receptor-associated factor 6 (TRAF6) expression in HKC. The effect of MSC-Exos on HKCs apoptosis after miR-125b knockdown was determined by flow cytometry. Moreover, dual-luciferase reporter assays were used to determine the targeting relationship between miR-125b and TRAF6 in HKCs. Our data revealed that MSC-Exos increased HG-induced autophagy in HKCs and reversed HKCs apoptosis. Moreover, our study found that miR-125b was enriched in MSC-Exos and directly targeted TRAF6 in HKCs. In addition, exosomally transferred miR-125b inhibited the apoptosis of HG-treated HKCs by mediating Akt signalling. In summary, MSC-derived exosomal miR-125b induced autophagy and inhibited apoptosis in HG-treated HKCs via the downregulation of TRAF6. Therefore, our study provided a new idea for DN treatment.

FOXO1-Mediated Downregulation of RAB27B Leads to Decreased Exosome Secretion in Diabetic Kidneys

Exosomes have been implicated in diabetic kidney disease (DKD), but the regulation of exosomes in DKD is largely unknown. Here, we have verified the decrease of exosome secretion in DKD and unveiled the underlying mechanism. In Boston University mouse proximal tubule (BUMPT) cells, high-glucose (HG) treatment led to a significant decrease in exosome secretion, which was associated with specific downregulation of RAB27B, a key guanosine-5'-triphosphatase in exosome secretion. Overexpression of RAB27B restored exosome secretion in HG-treated cells, suggesting a role of RAB27B downregulation in the decrease of exosome secretion in DKD. To understand the mechanism of RAB27B downregulation, we conducted bioinformatics analysis that identified FOXO1 binding sites in the Rab27b gene promoter. Consistently, HG induced phosphorylation of FOXO1 in BUMPT cells, preventing FOXO1 accumulation and activation in the nucleus. Overexpression of nonphosphorylatable, constitutively active FOXO1 led to the upregulation of RAB27B and an increase in exosome secretion in HG-treated cells. In vivo, compared with normal mice, diabetic mice showed increased FOXO1 phosphorylation, decreased RAB27B expression, and reduced exosome secretion. Collectively, these results unveil the mechanism of exosome dysfunction in DKD where FOXO1 is phosphorylated and inactivated in DKD, resulting in RAB27B downregulation and the decrease of exosome secretion.

Extracellular Vesicles in Organ Fibrosis: Mechanisms, Therapies, and Diagnostics

Fibrosis is the unrelenting deposition of excessively large amounts of insoluble interstitial collagen due to profound matrigenic activities of wound-associated myofibroblasts during chronic injury in diverse tissues and organs. It is a highly debilitating pathology that affects millions of people globally and leads to decreased function of vital organs and increased risk of cancer and end-stage organ disease. Extracellular vesicles (EVs) produced within the chronic wound environment have emerged as important vehicles for conveying pro-fibrotic signals between many of the cell types involved in driving the fibrotic response. On the other hand, EVs from sources such as stem cells, uninjured parenchymal cells, and circulation have in vitro and in vivo anti-fibrotic activities that have provided novel and much-needed therapeutic options. Finally, EVs in body fluids of fibrotic individuals contain cargo components that may have utility as fibrosis biomarkers, which could circumvent current obstacles to fibrosis measurement in the clinic, allowing fibrosis stage, progression, or regression to be determined in a manner that is accurate, safe, minimally-invasive, and conducive to repetitive testing. This review highlights the rapid and recent progress in our understanding of EV-mediated fibrotic pathogenesis, anti-fibrotic therapy, and fibrosis staging in the lung, kidney, heart, liver, pancreas, and skin.

Extracellular vesicle activities regulating macrophage- and tissue-mediated injury and repair responses

Macrophages are typically identified as classically activated (M1) macrophages and alternatively activated (M2) macrophages, which respectively exhibit pro- and anti-inflammatory phenotypes, and the balance between these two subtypes plays a critical role in the regulation of tissue inflammation, injury, and repair processes. Recent studies indicate that tissue cells and macrophages interact via the release of small extracellular vesicles (EVs) in processes where EVs released by stressed tissue cells can promote the activation and polarization of adjacent macrophages which can in turn release EVs and factors that can promote cell stress and tissue inflammation and injury, and vice versa. This review discusses the roles of such EVs in regulating such interactions to influence tissue inflammation and injury in a number of acute and chronic inflammatory disease conditions, and the potential applications, advantage and concerns for using EV-based therapeutic approaches to treat such conditions, including their potential role of drug carriers for the treatment of infectious diseases.

Urinary Extracellular Vesicles for Diabetic Kidney Disease Diagnosis

Diabetic kidney disease (DKD) is the leading cause of end stage renal disease (ESRD) in developed countries, affecting more than 40% of diabetes mellitus (DM) patients. DKD pathogenesis is multifactorial leading to a clinical presentation characterized by proteinuria, hypertension, and a gradual reduction in kidney function, accompanied by a high incidence of cardiovascular (CV) events and mortality. Unlike other diabetes-related complications, DKD prevalence has failed to decline over the past 30 years, becoming a growing socioeconomic burden. Treatments controlling glucose levels, albuminuria and blood pressure may slow down DKD evolution and reduce CV events, but are not able to completely halt its progression. Moreover, one in five patients with diabetes develop DKD in the absence of albuminuria, and in others nephropathy goes unrecognized at the time of diagnosis, urging to find novel noninvasive and more precise early diagnosis and prognosis biomarkers and therapeutic targets for these patient subgroups. Extracellular vesicles (EVs), especially urinary (u)EVs, have emerged as an alternative for this purpose, as changes in their numbers and composition have been reported in clinical conditions involving DM and renal diseases. In this review, we will summarize the current knowledge on the role of (u)EVs in DKD.