Neutrophil exosomes enhance the skin autoinflammation in generalized pustular psoriasis via activating keratinocytes

Pathogenesis and interaction of neutrophils and extracellular vesicles in noncancer liver diseases

Liver disease ranks as the eleventh leading cause of mortality, leading to approximately 2 million deaths annually worldwide. Neutrophils are a type of immune cell that are abundant in peripheral blood and play a vital role in innate immunity by quickly reaching the site of liver injury. They exert their influence on liver diseases through autocrine, paracrine, and immunomodulatory mechanisms. Extracellular vesicles, phospholipid bilayer vesicles, transport a variety of substances, such as proteins, nucleic acids, lipids, and pathogenic factors, for intercellular communication. They regulate cell communication and perform their functions by delivering biological information. Current research has revealed the involvement of the interaction between neutrophils and extracellular vesicles in the pathogenesis of liver disease. Moreover, more research has focused on targeting neutrophils as a therapeutic strategy to attenuate disease progression. Therefore, this article summarizes the roles of neutrophils, extracellular vesicles, and their interactions in noncancerous liver diseases.

Tissue gene expression profiles and communication networks inform candidate blood biomarker identification in psoriasis and atopic dermatitis

Overlapping clinical and pathomechanistic features can complicate the diagnosis and treatment of inflammatory skin diseases, including psoriasis and atopic dermatitis (AD). Spatial transcriptomics allows the identification of disease- and cell-specific molecular signatures that may advance biomarker development and future treatments. This study identified transcriptional signatures in keratinocytes and sub-basal CD4+ and CD8+ T lymphocytes from patients with psoriasis and AD. In silico prediction of ligand:receptor interactions delivered key signalling pathways (interferon, effector T cells, stroma cell and matrix biology, neuronal development, etc.). Targeted validation of selected transcripts, including CCL22, RELB, and JUND, in peripheral blood T cells suggests the chosen approach as a promising tool also in other inflammatory diseases. Psoriasis and AD are characterized by transcriptional dysregulation in T cells and keratinocytes that may be targeted therapeutically. Spatial transcriptomics is a valuable tool in the search for molecular signatures that can be used as biomarkers and/or therapeutic targets.

Extracellular vescicles in psoriasis: from pathogenesis to possible roles in therapy

Psoriasis is a chronic inflammatory disease affecting skin and joints characterized by a chronically altered immune and inflammatory response. Several factors occur from the onset to the development of this disease due to different types of cells spatially and temporally localized in the affected area, such as, keratinocytes, macrophages, neutrophils and T helper lymphocytes. This scenario leads to the chronic release of high levels of inflammatory mediators (i.e., IL-17, IL-23, IL-22, TNF-α, S100 proteins, Defensins) and lastly parakeratosis and thickening of the stratum spinosum. Extracellular vesicles (EVs) are small double membraned biological nanoparticles that are secreted by all cell types and classified, based on dimension and biogenesis, into exosomes, microvesicles and apoptotic bodies. Their role as vessels for long range molecular signals renders them key elements in the pathogenesis of psoriasis, as well as innovative platforms for potential biomarker discovery and delivery of fine-tuned anti-inflammatory therapies. In this review, the role of EVs in the pathogenesis of psoriasis and the modulation of cellular microenvironment has been summarized. The biotechnological implementation of EVs for therapy and research for new biomarkers has been also discussed.

The Immunology of Psoriasis-Current Concepts in Pathogenesis

Psoriasis is one of the most common inflammatory skin diseases with a chronic, relapsing-remitting course. The last decades of intense research uncovered a pathological network of interactions between immune cells and other types of cells in the pathogenesis of psoriasis. Emerging evidence indicates that dendritic cells, TH17 cells, and keratinocytes constitute a pathogenic triad in psoriasis. Dendritic cells produce TNF-α and IL-23 to promote T cell differentiation toward TH17 cells that produce key psoriatic cytokines IL-17, IFN-γ, and IL-22. Their activity results in skin inflammation and activation and hyperproliferation of keratinocytes. In addition, other cells and signaling pathways are implicated in the pathogenesis of psoriasis, including TH9 cells, TH22 cells, CD8+ cytotoxic cells, neutrophils, γδ T cells, and cytokines and chemokines secreted by them. New insights from high-throughput analysis of lesional skin identified novel signaling pathways and cell populations involved in the pathogenesis. These studies not only expanded our knowledge about the mechanisms of immune response and the pathogenesis of psoriasis but also resulted in a revolution in the clinical management of patients with psoriasis. Thus, understanding the mechanisms of immune response in psoriatic inflammation is crucial for further studies, the development of novel therapeutic strategies, and the clinical management of psoriasis patients. The aim of the review was to comprehensively present the dysregulation of immune response in psoriasis with an emphasis on recent findings. Here, we described the role of immune cells, including T cells, B cells, dendritic cells, neutrophils, monocytes, mast cells, and innate lymphoid cells (ILCs), as well as non-immune cells, including keratinocytes, fibroblasts, endothelial cells, and platelets in the initiation, development, and progression of psoriasis.

Unconjugated bilirubin and its derivative ameliorate IMQ-induced psoriasis-like skin inflammation in mice by inhibiting MMP9 and MAPK pathway

Psoriasis is a chronic immune-mediated inflammatory skin disease that involves dysregulated proliferation of keratinocytes. Psoriatic skin lesions are characterized by redness, thickness, and scaling. The interleukin axis of IL-23/IL-17 is critically involved in the development of human psoriasis. Imiquimod (IMQ), an agonist of TLR7 is known to induce psoriatic-like skin inflammation in mice. The topical application of IMQ induces systemic inflammation with increased proinflammatory cytokines in serum and secondary lymphoid organs. Further, matrix metalloproteases (MMPs) have been implicated in the pathophysiology of psoriatic-like skin inflammation. The increased MMP9 activity and gene expression of proinflammatory cytokines in IMQ-induced psoriatic skin is mediated by the activation of the MAPK pathway. Moreover, the increased expression of neutrophil-specific chemokines confirmed the infiltration of neutrophils at the site of psoriatic skin inflammation. In contrast, expression of IL-10, an anti-inflammatory cytokine gene expression is reduced in IMQ-treated mice skin. Topical application of unconjugated bilirubin (UCB) and its derivative dimethyl ester of bilirubin (BD1) on IMQ-induced psoriatic mice skin significantly mitigated the symptoms of psoriasis by inhibiting the activity of MMP9. Further, UCB and BD1 reduced neutrophil infiltration as evidenced by decreased myeloperoxidase (MPO) activity and reduced gene expression of proinflammatory cytokines, and neutrophil-specific chemokines. Apart from these modulations UCB and BD1 reduced MAPK phosphorylation and upregulated anti-inflammatory cytokines. To conclude, UCB and BD1 immunomodulated the psoriatic skin inflammation induced by IMQ in mice by inhibiting neutrophil mediated MMP9, decreased proinflammatory cytokines gene expression and modulating the MAPK pathway.

The implications of exosomes in psoriasis: disease: emerging as new diagnostic markers and therapeutic targets

As the largest human organ, the skin is continuously exposed to various external and internal triggers that affect body homeostasis. Psoriasis is a persistent inflammatory skin condition that has a major bearing on patients' physiological functioning as well as their mental well-being. It is an autoimmune disorder and has been the focus of extensive research efforts in recent years. Cells secrete exosomes into the environment surrounding them, which comprises a lipid bilayer. The movement of cellular components like microRNAs, mRNAs, DNA, lipids, metabolites, and cell-surface proteins is mediated by exosomes. Exosomes are crucial for inducing communication between cells. There has been extensive study of exosomes, both preclinical and clinical, looking at their potential role in autoimmune diseases. Besides the role that they play in the body's basic processes, exosomes are also considered an increasingly essential part as diagnostic and therapeutic agents. In the following article, we conduct a literature review of current studies related to molecular and structural aspects of exosomes. We emphasis on the function of exosomes in pathogenesis, as well as the possibility of their usage in medicinal applications and as biomarkers.

High Expression of miR-6785-5p in the Serum Exosomes of Psoriasis Patients Alleviates Psoriasis-Like Skin Damage by Interfering with the MNK2/p-eIF4E Axis in Keratinocytes

Psoriasis is a chronic inflammatory skin disease characterized by abnormal keratinocyte proliferation and inflammation. MiRNAs and serum exosomes participate in the pathogenesis of many diseases. The objective of this study is to explore the function of miR-6785-5p in psoriatic keratinocytes and its upstream and downstream mechanisms. For our study, we employed qRT-PCR and fluorescence in situ hybridization to evaluate miR-6785-5p in psoriatic keratinocytes and conducted a microRNA microarray for identifying differentially expressed miRNAs in patient serum exosomes. We then cocultured keratinocytes with these exosomes, using immunofluorescence staining and qRT-PCR to assess uptake and miR-6785-5p overexpression. We explored miR-6785-5p's role through transfection with specific mimics and inhibitors and confirmed MNK2 as its target using a luciferase assay. MNK2's function was further examined using siRNA technology. Lastly, we applied an imiquimod-induced psoriasis mouse model, also employing siRNA, to investigate MNK2's role in psoriasis. MiR-6785-5p demonstrates a notable overexpression in the keratinocytes of psoriasis patients as well as in their serum exosomes. These keratinocytes actively uptake the miR-6785-5p-enriched serum exosomes. Functionally, miR-6785-5p appears to alleviate psoriasis-like skin damage, observable both in vitro and in vivo, by downregulating MNK2 expression. Psoriasis keratinocytes uptake serum exosomes highly expressing miR-6785-5p. MiR-6785-5p inhibits the abnormal proliferation and inflammatory state of keratinocytes by reducing MNK2 expression and interfering with the MNK2/p-eIF4E axis.

Crosstalk between keratinocytes and neutrophils shapes skin immunity against S. aureus infection

Introduction

Staphylococcus aureus (S. aureus) infection of the skin leads to a rapid initial innate immune response with keratinocytes in the epidermis as the initial sensors. Polymorphonuclear neutrophils (PMNs) are the first innate immune cells to infiltrate infection sites where they provide an effective first-line of defense. Previous work of our group showed that in inflamed skin a crosstalk between PMNs and keratinocytes results in enhanced S. aureus skin colonization.

Methods

In this work, we used an in vitro co-culture model to studied the crosstalk between primary human keratinocytes (PHKs) and PMNs in a sterile environment and upon S. aureus infection. We investigated the influence of PHKs on PMN activation by analyzing PMN lifespan, expression of degranulation markers and induction of proinflammatory cytokines. Furthermore, we analyzed the influence of PMNs on the inflammatory response of PHKs. Finally, we investigated the influence of the skin microbiome on PMN-mediated skin inflammation.

Results

We show that co-culture of PMNs with PHKs induces activation and degranulation of PMNs and significantly enhances their lifespan compared to PMN cultivation alone by an IL-8 mediated mechanism and, furthermore, primes PMNs for enhanced activity after S. aureus infection. The prolonged incubation with PMNs also induces inflammatory responses in PHKs which are further exacerbated in the presence of S. aureus and induces further PMN recruitment thus fueling skin inflammation. Interestingly, infection of PHKs with the skin commensal S. epidermidis reduces the inflammatory effects of PMNs in the skin and exhibits an anti-inflammatory effect.

Discussion

Our data indicate that skin infiltrating PMNs and PHKs influence each other in such a way to enhance skin inflammation and that commensal bacteria are able to reduce the inflammatory effect.

Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in psoriasis: a systematic review and meta-analysis

Psoriasis is a chronic, inflammatory skin disorder characterized by well-demarcated erythematous lesions with surface scaling. The disease is underpinned by a dysregulated immune response with a shift in the balance of neutrophils, lymphocytes and platelets. We sought to evaluate the novel systemic inflammatory markers, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), as psoriatic indicators. Pubmed, Web of Science and Scopus were systematically searched for relevant studies. Twenty-four studies consisting of a total of 2,275 psoriatic patients (1,301 males and 974 females) and 2,334 healthy controls (1,401 males and 933 females) were identified for inclusion in the quantitative analysis. The NLR and PLR were found to be significantly increased in psoriatic patients [standardized mean difference (SMD) = 0.68, 95% CI 0.56-0.80, p < 0.01, and SMD = 0.37, 95% CI 0.14-0.60, p < 0.01, respectively]. However, no association between the NLR and PLR with psoriasis severity was detected (p = 0.93, and p = 0.83, respectively). In conclusion, the NLR and PLR are simple and cost-effective markers of psoriatic presence, but their value as severity markers requires further study.

Extracellular Vesicles in the Skin Microenvironment: Emerging Roles as Biomarkers and Therapeutic Tools in Dermatologic Health and Disease

The recent discovery of extracellular vesicles (EVs) carrying cargo consisting of various bioactive macromolecules that can modulate the phenotype of recipient target cells has revealed an important new mechanism through which cells can signal their neighbors and regulate their microenvironment. Because EV cargo and composition correlate with the physiologic state of their cell of origin, investigations into the role of EVs in disease pathogenesis and progression have become an area of intense study. The physiologic and pathologic effects of EVs on their microenvironment are incredibly diverse and include the modulation of molecular pathways involved in angiogenesis, inflammation, wound healing, epithelial-mesenchymal transition, proliferation, and immune escape. This review examines recent studies on the role of EVs in diseases of the skin and on how differences in EV composition and cargo can alter cell states and the surrounding microenvironment. We also discuss the potential clinical applications of EVs in skin disease diagnosis and management. We examine their value as an easily isolated source of biomarkers to predict disease prognosis or to monitor patient response to treatment. Given the ability of EVs to modulate disease-specific signaling pathways, we also assess their potential to serve as novel personalized precision therapeutic tools for dermatological diseases.

Emerging Role of the IL-36/IL-36R Axis in Multiple Inflammatory Skin Diseases

IL-36 is a most recent member of the IL-1 cytokine family, primarily expressed at barrier sites of the body such as the skin, lungs, and intestine. It plays a vital role in inflammation and is implicated in the development of various cutaneous; intestinal; and pulmonary disorders, including psoriasis, inflammatory bowel disease, and chronic obstructive pulmonary disease. IL-36 comprises 4 isoforms: the proinflammatory IL-36α, IL-36β, and IL-36γ and the anti-inflammatory IL-36R antagonist. An imbalance between proinflammatory and anti-inflammatory IL-36 isoforms can contribute to the inflammatory fate of cells and tissues. IL-36 cytokines signal through an IL-36R heterodimer mediating their function through canonical signaling cacade, including the NF-B pathway. Prominent for its role in psoriasis, IL-36 has recently been associated with disease mechanisms in atopic dermatitis, hidradenitis suppurativa, neutrophilic dermatoses, autoimmune blistering disease, and Netherton syndrome. The major cutaneous source of IL-36 cytokines is keratinocytes, pointing to its role in the communication between the epidermis, innate (neutrophils, dendritic cells) immune system, and adaptive (T helper [Th]1 cells, Th17) immune system. Thus, cutaneous IL-36 signaling is crucial for the immunopathological outcome of various skin diseases. Consequently, the IL-36/IL-36R axis has recently been recognized as a promising drug target for the treatment of inflammatory disorders beyond psoriasis. This review summarizes the current update on IL-36 cytokines in inflammatory skin diseases.

Exosomes released by environmental pollutant-stimulated Keratinocytes/PBMCs can trigger psoriatic inflammation in recipient cells via the AhR signaling pathway

Introduction: Exosomes, pivotal in intercellular communication during skin disease pathogenesis, have garnered substantial attention. However, the impact of environmental pollutants, such as benzo[a]pyrene (BaP) and 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), on exosome release amid inflammatory skin diseases remains unexplored. This study addresses this gap by examining the influence of BaP and TCDD on exosome function, specifically focusing on immune-related pathway alterations in normal recipient keratinocytes and peripheral blood mononuclear cells (PBMCs). Methods: HaCaT cells were treated with exosomes from BaP- or TCDD-treated keratinocytes. Proinflammatory cytokines and chemokines, including TNF-α, IL-1β, IL-6, IL-8, CXCL1, and CXCL5, were assessed. The involvement of the p65NF-κB/p38MAPK/ERK signaling pathway in recipient keratinocytes was investigated. Aryl hydrocarbon receptor (AhR) silencing was employed to elucidate its role in mediating the proinflammatory response induced by exosomes from BaP- or TCDD-treated keratinocytes. Results and discussion: Treatment with exosomes from BaP- or TCDD-treated keratinocytes induced a significant increase in proinflammatory cytokines and chemokines in HaCaT cells. The upregulation implicated the p65NF-κB/p38MAPK/ERK signaling pathway. AhR silencing attenuated this response, suggesting a role for AhR in mediating this response. In PBMCs from healthy controls, exosomes from BaP-stimulated PBMCs of psoriatic patients led to increased expression of proinflammatory cytokines and modulation of Th1/Th17 cell distribution via AhR activation. These findings unveil a novel dimension in the interplay between environmental xenobiotic agents (BaP and TCDD) and exosomal functions. The study establishes their influence on psoriatic inflammatory responses, shedding light on the underlying mechanisms mediated through the AhR signaling pathway in recipient keratinocytes and PBMCs.

Extracellular vesicles from keratinocytes and other skin-related cells in psoriasis: A review

Psoriasis is a highly prevalent chronic inflammatory skin condition involving abnormal proliferation and differentiation of keratinocytes, together with substantial infiltration of immune cells. Extracellular vesicles (EVs), which are released spontaneously into the extracellular space by virtually all cell types, play a crucial role in cell-to-cell communication by delivering bioactive cargos such as mRNA nucleic acids and proteins to recipient cells. Numerous studies have highlighted the significant contributions of EVs to both the pathogenesis and treatment of psoriasis. This review provides a concise overview of skin-derived EVs and their involvement in the pathogenesis of psoriasis.

Adipose-Derived Stem Cell Exosomes Alleviate Psoriasis Serum Exosomes-Induced Inflammation by Regulating Autophagy and Redox Status in Keratinocytes

Introduction

Exosomes play a key role in cell communication and are involved in both pathological and physiological processes. Autophagy dysfunction and oxidative stress are linked to immune-mediated inflammatory diseases such as psoriasis. Stem cell-derived exosomes exhibit immunomodulatory and antioxidant efficacy.

Methods

We aimed to investigate the impact of psoriasis serum-derived exosomes on inflammation, oxidative stress, and autophagy in keratinocytes. Additionally, we explored the therapeutic potential of adipose-derived stem cell (ADSC) exosomes against inflammation induced by psoriasis serum exosomes. To validate psoriasis patient serum-derived exosomes and ADSC exosomes, we used nanoparticle tracking analysis, Western blotting, flow cytometry, and immunofluorescence. qPCR was used to study changes in the gene expression of proinflammatory cytokines and oxidative stress markers in HaCaT cells treated with psoriasis serum-derived exosomes or ADSC exosomes. The effects of these exosomes on autophagy in HaCaT cells were evaluated by Western blotting and immunofluorescence.

Result

The treatment of HaCaT cells with psoriasis serum-derived exosomes increased proinflammatory cytokine production and oxidative stress-related factor (Nox2 and Nox4) expression and decreased Nrf2 expression via P65/NF-κB and P38/MAPK activation. Compared with healthy control serum-derived exosomes, psoriasis serum-derived exosomes decreased ATG5, P62, Beclin1, and LC3 expression and autophagosome production in HaCaT cells. Conversely, ADSC exosomes suppressed proinflammatory cytokine and oxidative stress production, and restored autophagy in HaCaT cells treated with psoriasis serum-derived exosomes.

Discussion

These findings suggest that ADSC exosomes exhibit a suppressive effect on psoriasis serum exosome-induced inflammation and oxidative stress by regulating autophagy in keratinocytes.

Exosomal microRNA-223 from neutrophil-like cells inhibits osteogenic differentiation of PDLSCs through the cGMP-PKG signaling pathway

BACKGROUND AND OBJECTIVE

Neutrophils-derived exosomes have been shown to cause tissue inflammation in many diseases, but their role in periodontitis, a neutrophil-mediated disease, is unknown. Here, we investigated the effect of neutrophil-like cells derived exosomes on osteogenic dysfunction of periodontal ligament stem cells (PDLSCs) in periodontitis.

METHODS

Neutrophil-like cells were derived from HL-60 cells by dimethylsulfoxide stimulation. Exosomes were isolated by ultracentrifugation and characterized using transmission electron microscopy, nanoflow cytometry and western blot. MicroRNA-223 (miR-223) expression were analyzed by real-time PCR. Western blot, alkaline phosphatase (ALP), and alizarin red staining were conducted to assess whether exosomes could affect the osteogenic differentiation of PDLSCs. The expression of miR-223 was inhibited in PDLSCs by transfecting with miR-223 inhibitor. Cyclic guanosine monophosphate (cGMP) expression was determined by enzyme-linked immunosorbent assay.

RESULTS

We found that miR-223 was significantly increased in neutrophils and neutrophil-like cells derived exosomes. Treatment with exosomes derived from neutrophil-like cells upregulated miR-223 expression and inhibited the osteogenic differentiation of PDLSCs, while transfection with miR-223 inhibitor significantly promoted PDLSCs osteogenic differentiation. In addition, co-treatment with KT5823, a cGMP-PKG pathway inhibitor, markedly abrogated the rescue effects of miR-223 inhibitor on the osteogenic differentiation of PDLSCs.

CONCLUSIONS

Our findings suggest that neutrophil-like cells derived exosomes might inhibit osteogenic differentiation of PDLSCs by transporting miR-223 and regulating the cGMP-PKG signaling pathway.

Exosomal miRNA-mediated intercellular communications and immunomodulatory effects in tumor microenvironments

Extracellular communication, in other words, crosstalk between cells, has a pivotal role in the survival of an organism. This communication occurs by different methods, one of which is extracellular vesicles. Exosomes, which are small lipid extracellular vesicles, have recently been discovered to have a role in signal transduction between cells inside the body. These vesicles contain important bioactive molecules including lipids, proteins, DNA, mRNA, and noncoding RNAs such as microRNAs (miRNAs). Exosomes are secreted by all cells including immune cells (macrophages, lymphocytes, granulocytes, dendritic cells, mast cells) and tumor cells. The tumor microenvironment (TME) represents a complex network that supports the growth of tumor cells. This microenvironment encompasses tumor cells themselves, the extracellular matrix, fibroblasts, endothelial cells, blood vessels, immune cells, and non-cellular components such as exosomes and cytokines. This review aims to provide insights into the latest discoveries concerning how the immune system communicates internally and with other cell types, with a specific focus on research involving exosomal miRNAs in macrophages, dendritic cells, B lymphocytes, and T lymphocytes. Additionally, we will explore the role of exosomal miRNA in the TME and the immunomodulatory effect.

Extracellular vesicles: a comprehensive review of their roles as biomarkers and potential therapeutics in psoriasis and psoriatic arthritis

Psoriasis is a chronic immune-mediated condition that affects the skin and joints, with current treatments still unable to offer a cure and long-term use of treatments posing health risks. Understanding the pathogenesis of the disease has helped identify new targets that have allowed for the expansion of the therapeutic arsenal. Extracellular vesicles (EVs) have recently emerged as pathophysiological mediators of psoriasis, and there have been increasing reports of EVs as potential biomarkers and therapeutics. Given their innate role as natural vehicles for cell-to-cell communication, EVs have vast potential in their ability to determine disease status based on EV-specific cargo as well as act as therapeutics because of their anti-inflammatory properties and potential for enhancement. In this review we summarize the role of EVs in the pathogenesis of psoriasis and discuss EVs as both diagnostic and therapeutic agents.

Livin upregulation in keratinocytes of psoriasis patients to promote adhesion molecule expression

BACKGROUND

Activation of keratinocytes (KCs) is the main pathological feature of psoriasis. KCs recruit neutrophils by releasing various antimicrobial peptides and chemokines, which is also related to the expression of KC adhesion molecules. However, the regulatory mechanism governing their expression is still unclear. Livin, an inhibitor of the apoptosis protein family member involved in proliferation and metastasis of tumor cells, is significantly increased in psoriatic lesions.

OBJECTIVES

The aim of this study was to investigate the role of Livin in regulating adhesion molecule expression in KCs and release of chemokines that promote the activation and adhesion of neutrophils.

METHODS

The expression of Livin in psoriasis patients, imiquimod mouse model, and the combination of IL-17 alpha, IL-22, IL-1 alpha, OSM, and TNF-α (Mix M5)-treated HaCaT cells were detected by immunofluorescence staining, RT-qPCR, and ELISA. Livin-overexpression and knockdown in HaCaT cells transfected with HIV-1-based lentiviral vectors were used to study the function of Livin using RNA-seq. Moreover, differences in the expression of HaCaT cell adhesion molecules after regulation of Livin expression and activation of neutrophils in the co-culture model were verified.

RESULTS

Livin was upregulated in the KCs of psoriasis patients, imiquimod mouse model and Mix M5-treated HaCaT cells compared with the control groups. Livin in HaCaT cells might regulate the expression of adhesion molecules in KCs.

CONCLUSION

Thus, Livin may be a key effector molecule that regulates the expression of adhesion molecules in KCs and promotes the activation and adhesion of neutrophils.

Exosomes as biomarkers and therapeutic delivery for autoimmune diseases: Opportunities and challenges

Exosomes are spherical lipid bilayer vesicles composed of lipids, proteins and nucleic acids that deliver signaling molecules through a vesicular transport system to regulate the function and morphology of target cells, thereby involving in a variety of biological processes, such as cell apoptosis or proliferation, and cytokine production. In the past decades, there are emerging evidence that exosomes play pivotal roles in the pathological mechanisms of several autoimmune diseases (ADs), including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes mellitus (T1DM), Sjogren's syndrome (SS), multiple sclerosis (MS), inflammatory bowel disease (IBD). systemic sclerosis (SSc), etc. Several publications have shown that exosomes are involved in the pathogenesis of ADs mainly through intercellular communication and by influencing the response of immune cells. The level of exosomes and the expression of nucleic acids can reflect the degree of disease progression and are excellent biomarkers for ADs. In addition, exosomes have the potential to be used as drug carriers thanks to their biocompatibility and stability. In this review, we briefly summarized the current researches regarding the biological functions of exosomes in ADs, and provided an insight into the potential of exosomes as biomarkers and therapeutic delivery for these diseases.

The emerging role of exosomes in innate immunity, diagnosis and therapy

Exosomes, which are nano-sized transport bio-vehicles, play a pivotal role in maintaining homeostasis by exchanging genetic or metabolic information between different cells. Exosomes can also play a vital role in transferring virulent factors between the host and parasite, thereby regulating host gene expression and the immune interphase. The association of inflammation with disease development and the potential of exosomes to enhance or mitigate inflammatory pathways support the notion that exosomes have the potential to alter the course of a disease. Clinical trials exploring the role of exosomes in cancer, osteoporosis, and renal, neurological, and pulmonary disorders are currently underway. Notably, the information available on the signatory efficacy of exosomes in immune-related disorders remains elusive and sporadic. In this review, we discuss immune cell-derived exosomes and their application in immunotherapy, including those against autoimmune connective tissue diseases. Further, we have elucidated our views on the major issues in immune-related pathophysiological processes. Therefore, the information presented in this review highlights the role of exosomes as promising strategies and clinical tools for immune regulation.

Plasma Exosomes from Children with Atopic Dermatitis May Promote Apoptosis of Keratinocytes and Secretion of Inflammatory Factors in vitro

Purpose

Exosomes are important regulators of keratinocytes (KCs) that have been implicated in a variety of skin disorders. The effect of circulatory exosomes on KCs in pediatric atopic dermatitis (AD) has not been well studied. This study aims to explore the effect of plasma exosomes on KC activation, apoptosis and inflammation in pediatric AD patients.

Patients and Methods

Exosomes were extracted from plasma collected from 20 pediatric AD patients and 20 age-matched healthy controls. AD-exosomes were added with KCs at concentrations of 0 g/L, 10 g/L, 20 g/L and 30 g/L. Proliferation of KCs in each group was measured using Ki67 staining flow cytometry. Apoptosis was measured using Annexin V-FITC/PI double staining flow cytometry. KCs were divided into three groups according to the source of the exosomes they were cultured with: patients with AD, healthy controls and blank controls. Q-PCR was used to detect the activation (K6) and differentiation (K10) of cells, as well as inflammatory indicators (thymic stromal lymphopoietin (TSLP) and IL-33).

Results

The proliferation rate of KCs treated with 20 g/L exosomes from AD patients was significantly lower than that of other groups, while the apoptosis rate was significantly increased. Additionally, expression levels of K6, K10, TSLP and IL-33 were all up-regulated compared to keratinocytes treated with exosomes from healthy controls.

Conclusion

Exosomes from the peripheral blood of pediatric AD patients can regulate the activation, apoptosis and inflammatory cytokine secretion of KCs in vivo, which may participate in the pathogenesis of AD.

Downregulation of miRNA miR-1305 and upregulation of miRNA miR-6785-5p may be associated with psoriasis

Background: The role of serum extracellular vesicles (EVs) is less known in psoriasis.

Objectives: To explore the transcriptomic profile of serum EVs and the potential biomarkers in psoriasis.

Methods: EVs were isolated by differential ultracentrifugation and identified by transmission electron microscope. The diameters of EVs were detected using nanoparticle tracking analysis. Serum EVs-keratinocyte interaction was observed through confocal fluorescence microscopy. miRNA microarray and mRNA microarray were performed in serum EVs (n = 4) and skin lesions (n = 3), respectively. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and fluorescence in situ hybridization were used to detect the expression of miRNAs in serum EVs and skin lesions (n = 15). Bioinformatics analysis was performed to predict the potential target genes and functions of miR-1305 and miR-6785-5p. Western blot, CCK-8 and enzyme-linked immunosorbent assay (ELISA) were used to detect the EVs’ biomarkers, keratinocytes proliferation and cytokines secretion.

Results: A total of 16 miRNAs and 1,725 mRNAs were significantly dysregulated in serum EVs and skin lesions, respectively. miR-1305 was down-regulated and miR-6785-5p was upregulated in both serum EVs and skin lesions. Serum EVs could be taken up by keratinocytes. miR-1305 was downregulated and miR-6785-5p were upregulated in keratinocytes after co-cultured with psoriasis serum EVs compared with controls. Psoriasis serum EVs promoted keratinocyte proliferation and the secretion of CCL20 and IL-8. Serum EVs miR-1305 and miR-6785-5p were associated with disease severity.

Conclusion: Serum EVs might be involved in the activation of keratinocytes through loaded miRNAs in psoriasis. Serum EVs miR-1305 and miR-6785-5p may be associated with psoriasis.

A Systematic Review of Keratinocyte Secretions: A Regenerative Perspective

Cell regenerative therapy is a modern solution for difficult-to-heal wounds. Keratinocytes, the most common cell type in the skin, are difficult to obtain without the creation of another wound. Stem cell differentiation towards keratinocytes is a challenging process, and it is difficult to reproduce in chemically defined media. Nevertheless, a co-culture of keratinocytes with stem cells usually achieves efficient differentiation. This systematic review aims to identify the secretions of normal human keratinocytes reported in the literature and correlate them with the differentiation process. An online search revealed 338 references, of which 100 met the selection criteria. A total of 80 different keratinocyte secretions were reported, which can be grouped mainly into cytokines, growth factors, and antimicrobial peptides. The growth-factor group mostly affects stem cell differentiation into keratinocytes, especially epidermal growth factor and members of the transforming growth factor family. Nevertheless, the reported secretions reflected the nature of the involved studies, as most of them focused on keratinocyte interaction with inflammation. This review highlights the secretory function of keratinocytes, as well as the need for intense investigation to characterize these secretions and evaluate their regenerative capacities.

Neutrophil Extracellular Traps and Neutrophil-Derived Extracellular Vesicles: Common Players in Neutrophil Effector Functions

Neutrophil granulocytes are a central component of the innate immune system. In recent years, they have gained considerable attention due to newly discovered biological effector functions and their involvement in various pathological conditions. They have been shown to trigger mechanisms that can either promote or inhibit the development of autoimmunity, thrombosis, and cancer. One mechanism for their modulatory effect is the release of extracellular vesicles (EVs), that trigger appropriate signaling pathways in immune cells and other target cells. In addition, activated neutrophils can release bactericidal DNA fibers decorated with proteins from neutrophil granules (neutrophil extracellular traps, NETs). While NETs are very effective in limiting pathogens, they can also cause severe damage if released in excess or cleared inefficiently. Since NETs and EVs share a variety of neutrophil molecules and initially act in the same microenvironment, differential biochemical and functional analysis is particularly challenging. This review focuses on the biochemical and functional parallels and the extent to which the overlapping spectrum of effector molecules has an impact on biological and pathological effects.

Role of exosomes in skin diseases

BACKGROUND

Exosomes, as a family member of extracellular vesicles, are cell-secreted nanoscale structures that play pivotal roles in regulating physiological and pathophysiological processes of the skin. Exosomes induce communication between cells and are responsible for transporting cellular components such as microRNAs, mRNAs, DNA, lipids, metabolites, and cell-surface proteins. Numerous preclinical and clinical trials searched the contribution of exosomes to skin functions and disorders. Thus, exosomes are gaining increasing attention within investigational dermatology. In advance, stem-cell-derived exosomes were integrated into the functional cosmetics industry nominated as cell-free regenerative medicine.

OBJECTIVE

This review aims to demonstrate the roles of exosomes in inflammatory skin disorders, stem cell, and tumor biology through a comprehensive evaluation of the diagnostic, prognostic, and therapeutic perspectives.

METHODS

A comprehensive literature search was performed using electronic online databases "PubMed" and "Google Scholar" using key words ''exosomes'', ''skin'', ''wound healing''.

CONCLUSION

Exosomes are regarded as promising diagnostic and prognostic biomarkers for various skin diseases. Future prospects are repurposing exosomes to treat skin disorders, either as drug carriers or drugs themselves.

The Inhibition of Osteoblast Viability by Monosodium Urate Crystal-Stimulated Neutrophil-Derived Exosomes

Background and Objective

Bone erosion is common in patients with gout. The role of neutrophil-derived exosomes in gouty bone erosion remains elusive. This study aimed to investigate the functions of the neutrophil-derived exosomes in the development of bone erosion in gout.

Methods

Neutrophil-derived exosomes were collected and assessed by transmission electron microscopy and nanoparticle tracking analysis. Cell counting kit-8 assay was applied to evaluate cell viability, and cell apoptosis was assessed by flow cytometry. In addition, quantitative Real-time PCR and Western blotting were used to determine the expression levels of alkaline phosphatase (ALP), osteoprotegerin (OPG), and receptor activator of nuclear factor-κB ligand (RANKL). Neutrophil-derived exosomes were tagged with PKH67. The miRNA expression profiles of exosomes and human fetal osteoblasts (hFOB) were compared using high-throughput sequencing. Functional miRNAs transfected into hFOB after co-incubation with exosomes were selected and validated by preliminary qPCR.

Results

Neutrophil-derived exosomes were stimulated by monosodium urate (MSU). The exosomes could inhibit the viability of the hFOB, and the expression levels of ALP and OPG were down-regulated, while the expression level of RANKL was up-regulated. However, there was no significant difference in the viability of osteoclasts and the expression of nuclear factor of activated T cells 1. Exosomes were observed in the cytoplasm under a confocal microscopy, confirming that exosomes could be taken up by hFOB. In total, 2590 miRNAs were found, of which 47 miRNAs were differentially expressed. Among the delivered miRNAs, miR-1246 exhibited the highest level of differential expression. The viability of hFOB was reduced by miR-1246 mimics and increased by miR-1246 inhibitors. There was no significant difference in hFOB apoptosis rate between the miR-1246 mimic and miR-1246 inhibitor group. MiR-1246 overexpression decreased the expression levels of ALP and OPG, whereas increasing the expression level of RANKL. In contrast, miR-1246 inhibitor increased the expression levels of ALP and OPG, while decreasing the expression level of RANKL. Neutrophil-derived exosomes stimulated by MSU could increase the expression of miR-1246.

Conclusion

Neutrophil-derived exosomes stimulated by MSU could inhibit the viability of osteoblasts.

Extracellular vesicle-mediated bidirectional communication between heart and other organs

In recent years, a wealth of studies has identified various molecular species released by cardiac muscle under physiological and pathological conditions that exert local paracrine and/or remote endocrine effects. Conversely, humoral factors, principally produced by organs such as skeletal muscle, kidney, or adipose tissue, may affect the function and metabolism of normal and diseased hearts. Although this cross communication within cardiac tissue and between the heart and other organs is supported by mounting evidence, research on the role of molecular mediators carried by exosomes, microvesicles, and apoptotic bodies, collectively defined as extracellular vesicles (EVs), is at an early stage of investigation. Once released in the circulation, EVs can potentially reach any organ where they transfer their cargo of proteins, lipids, and nucleic acids that exert potent biological effects on recipient cells. Although there are a few cases where such signaling was clearly demonstrated, the results from many other studies can only be tentatively inferred based on indirect evidence obtained by infusing exogenous EVs in experimental animals or by adding them to cell cultures. This area of research is in rapid expansion and most mechanistic interpretations may change in the near future; hence, the present review on the role played by EV-carried mediators in the two-way communication between heart and skeletal muscle, kidneys, bone marrow, lungs, liver, adipose tissue, and brain is necessarily limited. Nonetheless, the available data are already unveiling new, intriguing, and ample scenarios in cardiac physiology and pathophysiology.

Olfactomedin 4 Is a Biomarker for the Severity of Infectious Diseases

Biomarkers of infectious diseases are essential tools for patient monitoring, diagnostics, and prognostics. Here we review recent advances in our understanding of olfactomedin 4 (OLFM4) in neutrophil biology and of OLFM4 as a new biomarker for certain infectious diseases. OLFM4 is a neutrophil-specific granule protein that is expressed in a subset of human and mouse neutrophils. OLFM4 expression is upregulated in many viral and bacterial infections, as well as in malaria. OLFM4 appears to play an important role in regulating host innate immunity against bacterial infection. Further, higher expression of OLFM4 is associated with severity of disease for dengue virus, respiratory syncytial virus, and malaria infections. In addition, higher expression of OLFM4 or a higher percentage of OLFM4 + neutrophils is associated with poorer outcomes in septic patients. OLFM4 is a promising biomarker and potential therapeutic target in certain infectious diseases.

Enhanced Migratory Ability of Neutrophils Toward Epidermis Contributes to the Development of Psoriasis via Crosstalk With Keratinocytes by Releasing IL-17A

Microabscess of neutrophils in epidermis is one of the histological hallmarks of psoriasis. The axis of neutrophil–keratinocyte has been thought to play a critical role in the pathogenesis of psoriasis. However, the features and mechanism of interaction between the two cell types remain largely unknown. Herein, we found that blood neutrophils were increased in psoriasis patients, positively correlated with disease severity and highly expressed CD66b, but not CD11b and CD62L compared to healthy controls. Keratinocytes expressed high levels of psoriasis-related inflammatory mediators by direct and indirect interaction with neutrophils isolated from psoriasis patients and healthy controls. The capacity of neutrophils in provoking keratinocytes inflammatory response was comparable between the two groups and is dependent on IL-17A produced by itself. Neutrophils isolated from psoriasis patients displayed more transcriptome changes related to integrin and increased migration capacity toward keratinocytes with high CD11b expression on cell surface. Of interest, neutrophils were more susceptible to keratinocyte stimulation than to fibroblasts and human umbilical vein endothelial cells (HUVECs) in terms of CD11b expression and the production of ROS and NETs. In conclusion, neutrophils from psoriasis patients gain a strong capacity of IL-17A production and integrins expression that possibly facilitates their abilities to promote production of psoriasis-related inflammatory mediators and migration, a phenomenon likely induced by their interaction with keratinocytes but not with fibroblasts. These findings provide a proof-of-concept that development of new drugs targeting migration of neutrophils could be a more specific and safe solution to treat psoriasis.

Olfactomedin 4 regulates migration and proliferation of immortalized non-transformed keratinocytes through modulation of the cell cycle machinery and actin cytoskeleton remodelling

Olfactomedin 4 (OLFM4), a multifunctional matricellular protein, is involved in regulation of angiogenesis, innate immunity, inflammation, tumorigenesis and metastasis formation via modulation of important cellular processes like adhesion, proliferation, differentiation as well as apoptosis. In our previous work we demonstrated the upregulation of OLFM4 during liver regeneration and cutaneous wound healing. Here we studied the outcomes of OLFM4 downregulation in human immortalized keratinocytes - the HaCaT cells. The suppression of OLFM4 inhibited migration but enhanced the proliferation of these cells. By using proteomic, and phosphoproteomic analysis, we found that OLFM4 downregulation induced changes in the levels of 184 proteins and 348 phosphosites. An integrated pathway analysis suggested that the increased phosphorylation of CDK7 at Ser164 and Thr170 may serve as the key event in the activation of CDK2 and consequent activation of cell cycle progression. Furthermore, the decrease in GIT1 and WAVE2 protein levels were connected to the disorganization of the actin cytoskeleton, reduction of lamellipodia formation at the leading edge of HaCaT cells, and decrease in their migration capacity.

Exosomes for Regulation of Immune Responses and Immunotherapy

Exosomes are membrane-enveloped nanosized (30–150 nm) extracellular vesicles of endosomal origin produced by almost all cell types and encompass a multitude of functioning biomolecules. Exosomes have been considered crucial players of cell-to-cell communication in physiological and pathological conditions. Accumulating evidence suggests that exosomes can modulate the immune system by delivering a plethora of signals that can either stimulate or suppress immune responses, which have potential applications as immunotherapies for cancer and autoimmune diseases. Here, we discuss the current knowledge about the active biomolecular components of exosomes that contribute to exosomal function in modulating different immune cells and also how these immune cell-derived exosomes play critical roles in immune responses. We further discuss the translational potential of engineered exosomes as immunotherapeutic agents with their advantages over conventional nanocarriers for drug delivery and ongoing clinical trials.

Olfactomedin-4 improves cutaneous wound healing by promoting skin cell proliferation and migration through POU5F1/OCT4 and ESR1 signalling cascades

Olfactomedin-4 (OLFM4) is an olfactomedin-domain-containing glycoprotein, which regulates cell adhesion, proliferation, gastrointestinal inflammation, innate immunity and cancer metastasis. In the present study we investigated its role in skin regeneration. We found that OLFM4 expression is transiently upregulated in the proliferative phase of cutaneous wound healing in humans as well as in mice. Moreover, a significant increase in OLFM4 expression was detected in the skin of lesional psoriasis, a chronic inflammatory disease characterized by keratinocyte hyperproliferation. In vitro experiments demonstrated that OLFM4 selectively stimulated keratinocyte proliferation and increased both keratinocyte and fibroblast migration. Using proteotranscriptomic pathway analysis we revealed that transcription factors POU5F1/OCT4 and ESR1 acted as hubs for OLFM4-induced signalling in keratinocytes. In vivo experiments utilizing mouse splinted full-thickness cutaneous wound healing model showed that application of recombinant OLFM4 protein can significantly improve wound healing efficacy. Taken together, our results suggest that OLFM4 acts as a transiently upregulated inflammatory signal that promotes wound healing by regulating both dermal and epidermal cell compartments of the skin.

Extracellular Vesicles as Central Mediators of COPD Pathophysiology

Chronic obstructive pulmonary disease (COPD) is a complex, heterogeneous, smoking-related disease of significant global impact. The complex biology of COPD is ultimately driven by a few interrelated processes, including proteolytic tissue remodeling, innate immune inflammation, derangements of the host-pathogen response, aberrant cellular phenotype switching, and cellular senescence, among others. Each of these processes are engendered and perpetuated by cells modulating their environment or each other. Extracellular vesicles (EVs) are powerful effectors that allow cells to perform a diverse array of functions on both adjacent and distant tissues, and their pleiotropic nature is only beginning to be appreciated. As such, EVs are candidates to play major roles in these fundamental mechanisms of disease behind COPD. Furthermore, some such roles for EVs are already established, and EVs are implicated in significant aspects of COPD pathogenesis. Here, we discuss known and potential ways that EVs modulate the environment of their originating cells to contribute to the processes that underlie COPD.

Lipocalin 2 Mediates Skin Inflammation in Psoriasis via the SREBP2-NLRC4 Axis

Lipocalins are a family of secreted adipokines that regulate cell lipid metabolism and immune responses. Although we have previously revealed that lipocalin 2 (LCN2) modulates neutrophil activation in psoriasis, the other roles of LCN2 in psoriatic local inflammation have remained elusive. Here, we found that 24p3R, the well-known specific receptor of LCN2, was highly expressed in the lesional epidermis of psoriasis patients. Silencing 24p3R alleviated hyperkeratosis, inflammatory cell infiltration, and overexpression of inflammatory mediators in an imiquimod (IMQ)-induced psoriasis-like mouse model. In vitro, LCN2 enhanced the expression of pro-inflammatory factors in primary keratinocytes, such as interleukin (IL)-1β, IL-23, C-X-C motif chemokine ligand (CXCL)1, and CXCL10, which was paralleled by enforced cholesterol biosynthetic signaling. Importantly, taking in vivo and in vitro approaches, we discovered the sterol response element binding factor 2 (SREBP2), a vital transcriptional factor in cholesterol synthesis pathway, as the critical mediator of LCN2-induced keratinocyte activation, which bond to the promoter region of NLR-family CARD-containing protein 4 (NLRC4). Suppressing SREBP2 in mice attenuated NLRC4 signaling and psoriasis-like dermatitis. Taken together, this study identifies the critical role of LCN2-SREBP2-NLRC4 axis in the pathogenesis of psoriasis, and proposes 24p3R or SREBP2 as potential therapeutic target for psoriasis.

Exosome as a Delivery Vehicle for Cancer Therapy

Exosomes are small extracellular vesicles that are naturally produced and carry biomolecules such as proteins, microRNAs, and metabolites. Because of their small size and low level of biomolecule expression, the biological function of exosomes has only been identified recently. Despite the short history of investigation, exosomes seem to have remarkable potential as a delivery vehicle. With regards to cancer therapy, numerous antitumor agents demonstrate serious side effects (or toxicity), which has led to the unmet need for improving their selectivity and stability. Exosomes, either produced naturally or generated artificially, provide an attractive platform to load many types of molecules such as small molecules, biologics, and other therapeutic agents. Furthermore, the features of exosomes can be designed by selecting their source cells, or they can be engineered to incorporate affinity tags; thus, exosomes show promise as effective delivery vehicles for the complex tumor microenvironment. In this review, we focus on various exosomes produced from different cell types and their potential uses. Moreover, we summarize the current state of artificial exosomes as a drug carrier and provide an overview of the techniques used for their production.

Neutrophils: Driving inflammation during the development of hepatocellular carcinoma

The relationship between immune and inflammatory responses in hepatocellular carcinoma (HCC) has garnered significant interest. In the peripheral blood and tumour microenvironment (TME), neutrophils, which are innate immune cells, crucially respond to various inflammatory factors, leading to tumour progression. To some extent, they affect the clinical treatment strategy and survival among HCC patients. A high circulating neutrophil-to-lymphocyte ratio is a reliable factor that can be used to predict poor outcomes in HCC patients. However, the mechanisms underlying the protumoural effects of circulating neutrophils remain poorly understood. Besides, the distinct role and function of neutrophils at the site of HCC remain relatively unclear, which is partially attributed to their substantial heterogeneity compared with other immune cells. In this review, we firstly discuss the current information available, detailing distinct subsets, functional phenotypes, and the impact of circulating and tumour-infiltrating neutrophils on tumourigenesis in HCC. Furthermore, we describe recent pre-clinical and clinical studies concerning neutrophils for evaluating the feasibility of targeting diverse protumoural aspects to improve therapeutic efficacy, thus paving the way for neutrophil-based treatment, especially in combination with immunotherapy.

The Functional Roles of RNAs Cargoes Released by Neutrophil-Derived Exosomes in Dermatomyositis

Dermatomyositis (DM) is an idiopathic inflammatory myopathy characterized by cutaneous manifestations. We first identified the profiles of noncoding RNAs (lncRNAs and miRNAs) in peripheral neutrophil exosomes (EXOs) of DM patients and explored their potential functional roles. Bioinformatics analyses were performed with R packages. Real-time quantitative PCR was used to validate the altered RNAs in DM neutrophil EXO-stimulated human dermal microvascular endothelial cells (HDMECs) and human skeletal muscle myoblasts (HSkMCs). In DM neutrophil EXOs, 124 upregulated lncRNAs (with 1,392 target genes), 255 downregulated lncRNAs (with 1867 target genes), 17 upregulated miRNAs (with 2,908 target genes), and 15 downregulated miRNAs (with 2,176 target genes) were identified. GO analysis showed that the differentially expressed (DE) lncRNAs and DE miRNAs participated in interleukin-6 and interferon-beta production, skeletal muscle cell proliferation and development, and endothelial cell development and differentiation. KEGG analysis suggested that DE lncRNAs and DE miRNAs were enriched in the PI3K–Akt, MAPK, AMPK and FoxO signalling pathways. Many novel and valuable DE lncRNAs and DE miRNAs interacted and cotargeted in the PI3K–Akt, MAPK, AMPK and FoxO signalling pathways. Our study suggests that neutrophil EXOs participate in DM pathogenesis through lncRNAs and miRNAs in the PI3K–Akt, MAPK, AMPK and FoxO signalling pathways.

Compositional Features of Distinct Microbiota Base on Serum Extracellular Vesicle Metagenomics Analysis in Moderate to Severe Psoriasis Patients

The bacterial microbiota in the skin and intestine of patients with psoriasis were different compared with that of healthy individuals. However, the presence of a distinct blood microbiome in patients with psoriasis is yet to be investigated. In this study, we investigated the differences in bacterial communities in plasma-derived extracellular vesicles (EVs) between patients with moderate to severe psoriasis (PSOs) and healthy controls (HCs). The plasma EVs from the PSO (PASI > 10) (n = 20) and HC (n = 8) groups were obtained via a series of centrifugations, and patterns were examined and confirmed using transmission electron microscopy (TEM) and EV-specific markers. The taxonomic composition of the microbiota was determined by using full-length 16S ribosomal RNA gene sequencing. The PSO group had lower bacterial diversity and richness compared with HC group. Principal coordinate analysis (PCoA)-based clustering was used to assess diversity and validated dysbiosis for both groups. Differences at the level of amplicon sequence variant (ASV) were observed, suggesting alterations in specific ASVs according to health conditions. The HC group had higher levels of the phylum Firmicutes and Fusobacteria than in the PSO group. The order Lactobacillales, family Brucellaceae, genera Streptococcus, and species Kingella oralis and Aquabacterium parvum were highly abundant in the HC group compared with the PSO group. Conversely, the order Bacillales and the genera Staphylococcus and Sphihgomonas, as well as Ralstonia insidiosa, were more abundant in the PSO group. We further predicted the microbiota functional capacities, which revealed significant differences between the PSO and HC groups. In addition to previous studies on microbiome changes in the skin and gut, we demonstrated compositional differences in the microbe-derived EVs in the plasma of PSO patients. Plasma EVs could be an indicator for assessing the composition of the microbiome of PSO patients.

Generalized Pustular Psoriasis: Divergence of Innate and Adaptive Immunity

Generalized pustular psoriasis (GPP) is a severe, relapsing, immune-mediated disease characterized by the presence of multiple sterile pustules all over the body. The exact pathomechanisms behind GPP remain elusive, although increased interest in the genetic basis and immunological disturbances have provided some revealing insights into the underlying signaling pathways and their mutual interaction. The genetic background of GPP has been thoroughly investigated over the past few years. The conducted studies have identified genetic variants that predispose to pustular forms of psoriasis. The loss-of-function mutation of the interleukin 36 receptor antagonist gene, along with rare gain-of-function mutations in the gene that encodes the keratinocyte signaling molecule (CARD14), are examples of the uncovered abnormalities. Interleukin 36 (IL-36), along with neutrophils, is now considered a central cytokine in GPP pathogenesis, with IL-36 signaling providing a link between innate and adaptive immune responses. More recently, a new concept of inflammation, caused by a predominantly genetically determined abnormal activation of innate immune response and leading to inflammatory keratinization, has arisen. GPP is currently considered a representative of this novel group of skin conditions, called autoinflammatory keratinization diseases. As no therapeutic agents have been approved for GPP to date in the United States and Europe, the novel anti-IL-36R antibodies are particularly promising and may revolutionize management of the disease.

MicroRNA-223 inhibits neutrophil extracellular traps formation through regulating calcium influx and small extracellular vesicles transmission

Modulation of miRNAs and neutrophil extracellular traps (NETs) formation are both implicated in inflammatory disorders. Adult-onset Still's disease (AOSD) is a systemic autoinflammatory disease with neutrophilic leukocytosis and unknown etiology. Although the NETs formation is elevated in AOSD patients, the regulatory roles of miRNAs in NETs formation in AOSD remains unclear. We revealed that the circulating levels of IL-18, NETs, and miR-223 were significantly higher in active AOSD patients, compared with inactive AOSD patients or healthy controls (P < 0.005). Moreover, IL-18 increased calcium influx into neutrophils, which led to mitochondrial ROS (mROS) production and NETs formation. Elevated levels of NETs-DNA could induce miR-223 expression in neutrophils through activating Toll-like receptor 9. The upregulated miR-223 expression in neutrophils suppressed mROS production by blocking calcium influx, and subsequently inhibited IL-18-mediated NETs formation. Besides, the increased neutrophil-derived exosomal miR-223 levels were observed in active AOSD patients compared with healthy controls (P < 0.005). Our in vitro assays demonstrated that the neutrophil-derived small extracellular vesicles carried miR-223, which could repress IL-18 production in macrophages. Together, these results suggest a fine-tuned mechanism between inflammatory (IL-18 induced NETs) and anti-inflammatory (miR-223) factors in AOSD. MiR-223, mROS inhibitors, and calcium channel blockers are the potential therapeutics for autoinflammatory diseases such as AOSD.

Neutrophil NETworking in ENL: Potential as a Putative Biomarker: Future Insights

Erythema nodosum leprosum (ENL), also known as type 2 reaction (T2R) is an immune complex mediated (type III hypersensitivity) reactional state encountered in patients with borderline lepromatous and lepromatous leprosy (BL and LL) either before, during, or after the institution of anti-leprosy treatment (ALT). The consequences of ENL may be serious, leading to permanent nerve damage and deformities, constituting a major cause of leprosy-related morbidity. The incidence of ENL is increasing with the increasing number of multibacillary cases. Although the diagnosis of ENL is not difficult to make for physicians involved in the care of leprosy patients, its management continues to be a most challenging aspect of the leprosy eradication program: the chronic and recurrent painful skin lesions, neuritis, and organ involvement necessitates prolonged treatment with prednisolone, thalidomide, and anti-inflammatory and immunosuppressive drugs, which further adds to the existing morbidity. In addition, the use of immunosuppressants like methotrexate, azathioprine, cyclosporine, or biologics carries a risk of reactivation of persisters (Mycobacterium leprae), apart from their own end-organ toxicities. Most ENL therapeutic guidelines are primarily designed for acute episodes and there is scarcity of literature on management of patients with chronic and recurrent ENL. It is difficult to predict which patients will develop chronic or recurrent ENL and plan the treatment accordingly. We need simple point-of-care or ELISA-based tests from blood or skin biopsy samples, which can help us in identifying patients who are likely to require prolonged treatment and also inform us about the prognosis of reactions so that appropriate therapy may be started and continued for better ENL control in such patients. There is a significant unmet need for research for better understanding the immunopathogenesis of, and biomarkers for, ENL to improve clinical stratification and therapeutics. In this review we will discuss the potential of neutrophils (polymorphonuclear granulocytes) as putative diagnostic and prognostic biomarkers by virtue of their universal abundance in human blood, functional versatility, phenotypic heterogeneity, metabolic plasticity, differential hierarchical cytoplasmic granule mobilization, and their ability to form NETs (neutrophil extracellular traps). We will touch upon the various aspects of neutrophil biology relevant to ENL pathophysiology in a step-wise manner. We also hypothesize about an element of metabolic reprogramming of neutrophils by M. leprae that could be investigated and exploited for biomarker discovery. In the end, a potential role for neutrophil derived exosomes as a novel biomarker for ENL will also be explored.

Neutrophils as Drivers of Immune Dysregulation in Autoimmune Diseases with Skin Manifestations

Dysregulation in the phenotype and function of neutrophils may play important roles in the initiation and perpetuation of autoimmune responses, including conditions affecting the skin. Neutrophils can have local and systemic effects on innate and adaptive immune cells as well as on resident cells in the skin, including keratinocytes (KCs). Aberrant formation/clearance of neutrophil extracellular traps (NETs) in systemic autoimmunity and chronic inflammatory diseases have been associated with the externalization of modified autoantigens in peripheral blood and tissues. NETs can impact the function of many cells, including macrophages, lymphocytes, dendritic cells, fibroblasts, and KCs. Emerging evidence has unveiled the pathogenic key roles of neutrophils in systemic lupus erythematosus, idiopathic inflammatory myopathies, psoriasis, hidradenitis suppurativa, and other chronic inflammatory conditions. As such, neutrophil-targeting strategies represent promising therapeutic options for these diseases.

Evaluation of neutrophil extracellular trap deregulated formation in pyoderma gangrenosum

Pyoderma gangrenosum (PG) is a neutrophilic dermatose (ND) characterized by a dense neutrophilic infiltrate in the affected tissue. Neutrophil extracellular traps (NETs) are web-like structures released by neutrophils and composed of cytosolic and granule proteins assembled on a scaffold of decondensed chromatin. Very little is known about the role of NETosis in PG. Here, we assessed the possible implication of NETosis in the pathogenesis of PG by investigating the NETosis in the ulcers of 26 PG patients. We demonstrated that neutrophils in the PG skin lesions undergo an aberrant level of NETosis in 100% of the analysed cases (N = 26). All control and abscess biopsies were instead negative for the NETosis. In addition, neutrophils from peripheral blood of PG patients showed a significantly higher rate of spontaneous, but not induced, NETosis. Overall, this study suggests that the NETosis may contribute to systemic inflammation and tissue destruction in PG, thus representing a possible novel therapeutic target.

Extracellular Vesicles as Potential Theranostic Platforms for Skin Diseases and Aging

Extracellular vesicles (EVs), naturally secreted by cells, act as mediators for communication between cells. They are transported to the recipient cells along with cargoes such as nucleic acids, proteins, and lipids that reflect the changes occurring within the parent cells. Thus, EVs have been recognized as potential theranostic agents for diagnosis, treatment, and prognosis. In particular, the evidence accumulated to date suggests an important role of EVs in the initiation and progression of skin aging and various skin diseases, including psoriasis, systemic lupus erythematosus, vitiligo, and chronic wounds. This review highlights recent research that investigates the role of EVs and their potential as biomarkers and therapeutic agents for skin diseases and aging.

Extracellular vesicles: Critical players during cell migration

Cell migration is essential for the development and maintenance of multicellular organisms, contributing to embryogenesis, wound healing, immune response, and other critical processes. It is also involved in the pathogenesis of many diseases, including immune deficiency disorders and cancer metastasis. Recently, extracellular vesicles (EVs) have been shown to play important roles in cell migration. Here, we review recent studies describing the functions of EVs in multiple aspects of cell motility, including directional sensing, cell adhesion, extracellular matrix (ECM) degradation, and leader-follower behavior. We also discuss the role of EVs in migration during development and disease and the utility of imaging tools for studying the role of EVs in cell migration.

The novel mechanisms and applications of exosomes in dermatology and cutaneous medical aesthetics

Exposure to the external environment may lead to instability and dysfunction of the skin, resulting in refractory wound, skin aging, pigmented dermatosis, hair loss, some immune-mediated dermatoses, and connective tissue diseases. Nowadays, many skin treatments have not achieved a commendable balance between medical recovery and cosmetic needs. Exosomes are cell-derived nanoscale vesicles carrying various biomolecules, including proteins, nucleic acids, and lipids, with the capability to communicate with adjacent or distant cells. Recent studies have demonstrated that endogenic multiple kinds of exosomes are crucial orchestrators in shaping physiological and pathological development of the skin. Besides, exogenous exosomes, such as stem cell exosomes, can serve as novel treatment options to repair, regenerate, and rejuvenate skin tissue. Herein, we review new insights into the role of endogenic and exogenous exosomes in the skin microenvironment and recent advances in applications of exosomes related to dermatology and cutaneous medical aesthetics. The deep understanding of the mechanisms by which exosomes perform biological functions in skin is of great potential to establish attractive therapeutic methods for the skin.

Exosomes: Emerging Diagnostic and Therapeutic Targets in Cutaneous Diseases

Skin is the largest human organ and is continuously exposed to various exogenous and endogenous trigger factors affecting body homeostasis. A number of mechanisms, including genetic, inflammatory and autoimmune ones, have been implicated in the pathogenesis of cutaneous diseases. Recently, there has been considerable interest in the role that extracellular vesicles, particularly exosomes, play in human diseases, through their modulation of multiple signaling pathways. Exosomes are nano-sized vesicles secreted by all cell types. They function as cargo carriers shuttling proteins, nucleic acids, lipids etc., thus impacting the cell-cell communications and transfer of vital information/moieties critical for skin homeostasis and disease pathogenesis. This review summarizes the available knowledge on how exosomes affect pathogenesis of cutaneous diseases, and highlights their potential as future targets for the therapy of various skin diseases.

Exosome-based immunotherapy: a promising approach for cancer treatment

In the era of the rapid development of cancer immunotherapy, there is a high level of interest in the application of cell-released small vesicles that stimulate the immune system. As cell-derived nanovesicles, exosomes show great promise in cancer immunotherapy because of their immunogenicity and molecular transfer function. The cargoes carried on exosomes have been recently identified with improved technological advances and play functional roles in the regulation of immune responses. In particular, exosomes derived from tumor cells and immune cells exhibit unique composition profiles that are directly involved in anticancer immunotherapy. More importantly, exosomes can deliver their cargoes to targeted cells and thus influence the phenotype and immune-regulation functions of targeted cells. Accumulating evidence over the last decade has further revealed that exosomes can participate in multiple cellular processes contributing to cancer development and therapeutic effects, showing the dual characteristics of promoting and suppressing cancer. The potential of exosomes in the field of cancer immunotherapy is huge, and exosomes may become the most effective cancer vaccines, as well as targeted antigen/drug carriers. Understanding how exosomes can be utilized in immune therapy is important for controlling cancer progression; additionally, exosomes have implications for diagnostics and the development of novel therapeutic strategies. This review discusses the role of exosomes in immunotherapy as carriers to stimulate an anti-cancer immune response and as predictive markers for immune activation; furthermore, it summarizes the mechanism and clinical application prospects of exosome-based immunotherapy in human cancer.