Plasma-derived DNA containing-extracellular vesicles induce STING-mediated proinflammatory responses in dermatomyositis

Suppressed activation of the IRF7 and TLR9 by JAK2V617F gold nanoparticles

Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPNs) are characterized by the overproduction of myeloid cells and a lack of response to cytokine signaling, along with genomic instability and the accumulation of nucleic acids in the cytoplasm. In this study, we investigated the effects of oligonucleotide-gold nanoparticle conjugates (ON-GNPs) targeting JAK2 or JAK2V617F mRNAs on nucleic acid-sensing pathways in HEL, SET2, and K562 cell lines. We evaluated changes in gene expression related to TLR9 and cGAS/STING pathways, RAGE/TLR9 receptor dynamics, and inflammatory cytokine release over short-term (0.5-2 h) and long-term (24-72 h) exposures. Our results demonstrated that ON-GNPs transiently suppressed TLR9, IRF7, and NFKB1 expression during the short term, followed by significant upregulation after 24 h, persisting up to 72 h. Notably, JAK2V617F-targeting ON-GNPs induced heightened IRF7 activation in HEL and SET2 cells after 24 h without affecting TLR9/RAGE expression. Additionally, IL-8 secretion increased in HEL and SET2 culture media after 72 h, correlating with interferon pathway activation. This study reveals that complementary ON-GNPs can modulate nucleic acid-sensing pathways, suppressing IL-8 and inflammatory signaling in the short term while inducing delayed activation of TLR9 and IRF7 in the presence of JAK2V617F. These findings provide a promising foundation for developing ON-GNP-based therapeutic strategies to manage inflammation and disease progression in Ph-MPNs.

"Extracellular Vesicle DNA: Advances and Applications as a Non-Invasive Biomarker in Disease Diagnosis and Treatment"

Extracellular vesicles (EVs) are nanoscale, membrane-enclosed structures released by cells into the extracellular milieu. These vesicles encapsulate a diverse array of molecular constituents, including nucleic acids, proteins, and lipids, which provide insights into the physiological or pathological conditions of their parent cells. Despite their potential, the study of EV-derived DNA (EV-DNA) has gathered relatively limited attention. This review aims to present a thorough examination of the emerging knowledge surrounding the utility of EV-DNA as a non-invasive biomarker across a spectrum of diseases. The review delves into various mechanisms underlying DNA packaging within EVs and the prevalent methodologies employed for extraction of EV-DNA. The relevance of EV-DNA is assessed across numerous health conditions, notably cancer, cardiovascular diseases, neurodegenerative disorders, infectious diseases, and pregnancy-related complications. The use of EV-DNA for cancer mutation detection has demonstrated remarkable sensitivity and specificity, thereby enhancing both diagnostic accuracy and therapeutic monitoring. In the context of cardiovascular diseases, EV-DNA serves as a predictive marker for events such as myocardial infarctions and shows a correlation with the severity of the disease. With respect to neurodegenerative conditions, including Parkinson's and Alzheimer's, EV-DNA contributes to the understanding of disease mechanisms and progression. Additionally, it plays an essential role in modulating immune tolerance and facilitating communication between maternal and fetal systems. Although there is a pressing need for standardized protocols for EV isolation and DNA analysis to facilitate clinical implementation, the prospect of EV-DNA as a non-invasive biomarker for diagnostic and prognostic purposes across diverse pathological conditions is considerable.

Extracellular vesicle autoantibodies

Autoantibodies are immunoglobulin proteins produced by autoreactive B cells responding to self-antigens. Extracellular vesicles (EVs) are membranous structures released by almost all types of cells and extensively distributed in various biological fluids. Studies have indicated that EVs loaded with self-antigens not only play important roles in antigen presentation and autoantibody production but can also form functional immune complexes with autoantibodies (termed EV autoantibodies). While numerous papers have summarized the production and function of pathogenic autoantibodies in diseases, especially autoimmune diseases, reviews on EV autoantibodies are rare. In this review, we outline the existing knowledge about EVs, autoantibodies, and EV antigens, highlighting the formation of EV autoantibodies and their functions in autoimmune diseases and cancers. In conclusion, EV autoantibodies may be involved in the occurrence of disease(s) and also serve as potential non-invasive markers that could help in the diagnosis and/or prognosis of disease. Additional studies designed to define in more detail the molecular characteristics of EV autoantibodies and their contribution to disease are recommended.

Keratinocyte derived extracellular vesicles mediated crosstalk between epidermis and dermis in UVB-induced skin inflammation

BACKGROUND AND RATIONALE

Ultraviolet-B (UVB) light induces dermal inflammation, although it is mostly absorbed in the epidermis. Recent reports suggest extracellular vesicles (EVs) act as a mediator of photodamage signaling. Melatonin is reported to be a protective factor against UV-induced damage. We hypothesized that EVs derived from UVB-irradiated keratinocytes might trigger proinflammatory responses in dermal cells and tested whether melatonin can ameliorate UVB-induced inflammation.

METHODS

We used UVB-irradiated HaCaT cells, primary keratinocytes and STING knock-out mice to model production of EVs under photodamaging conditions and performed immunoblotting and ELISA to measure their effect on dermal macrophages.

RESULTS

UVB-irradiated keratinocytes produce an increased number of EVs that contain higher concentrations of DNA and protein compared with controls. KC-derived EVs (KEVs) induced a STING- and inflammasome-mediated proinflammatory response in macrophages in vitro, and a pronounced inflammatory infiltrate in mouse dermis in vivo. Melatonin ameliorated KEVs inflammatory effect both in vitro and in vivo.

CONCLUSIONS

This data suggests EVs are mediators in a crosstalk that takes place between keratinocytes and their neighboring cells as a result of photodamage. Further studies exploring EVs induced by damaging doses of UVB, and their impact on other cells will provide insight into photodamage and may help develop targeted therapeutic approaches.

The negative effects of extracellular vesicles in the immune system

Immunity is a critical self-defense mechanism of the human body, wherein immune cells and immune molecules play a crucial role. Extracellular vesicles (EVs), derived from immune cells or other cells, play a significant role in tumors, autoimmune diseases and other immune-related disorders by serving as carriers and facilitating intercellular communication through the transfer of cargoes. Numerous studies have revealed that EVs can exacerbate disease development by modulating immune responses. Therefore, this paper focuses on the effects of EVs on the number, activity and function of different types of immune cells and the release of immune molecules (such as cytokines, antigens, antibodies, etc) in various diseases, as well as the roles of EVs associated with different types of immune cells in various diseases. We aim to provide a comprehensive review of the negative effects that EVs play in the immune system to provide more ideas and strategies for the management of clinical immune diseases.

Extracellular vesicle-associated DNA: ten years since its discovery in human blood

Extracellular vesicles (EVs) have emerged as key players in intercellular communication, facilitating the transfer of crucial cargo between cells. Liquid biopsy, particularly through the isolation of EVs, has unveiled a rich source of potential biomarkers for health and disease, encompassing proteins and nucleic acids. A milestone in this exploration occurred a decade ago with the identification of extracellular vesicle-associated DNA (EV-DNA) in the bloodstream of a patient diagnosed with pancreatic cancer. Subsequent years have witnessed substantial advancements, deepening our insights into the molecular intricacies of EV-DNA emission, detection, and analysis. Understanding the complexities surrounding the release of EV-DNA and addressing the challenges inherent in EV-DNA research are pivotal steps toward enhancing liquid biopsy-based strategies. These strategies, crucial for the detection and monitoring of various pathological conditions, particularly cancer, rely on a comprehensive understanding of why and how EV-DNA is released. In our review, we aim to provide a thorough summary of a decade's worth of research on EV-DNA. We will delve into diverse mechanisms of EV-DNA emission, its potential as a biomarker, its functional capabilities, discordant findings in the field, and the hurdles hindering its clinical application. Looking ahead to the next decade, we envision that advancements in EV isolation and detection techniques, coupled with improved standardization and data sharing, will catalyze the development of novel strategies exploiting EV-DNA as both a source of biomarkers and therapeutic targets.

Immune-mediated necrotizing myopathy: A comprehensive review of the pathogenesis, clinical features, and treatments

Immune-mediated necrotizing myopathy (IMNM) is a rare and newly recognized autoimmune disease within the spectrum of idiopathic inflammatory myopathies. It is characterized by myositis-specific autoantibodies, elevated serum creatine kinase levels, inflammatory infiltrate, and weakness. IMNM can be classified into three subtypes based on the presence or absence of specific autoantibodies: anti-signal recognition particle myositis, anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase myositis, and seronegative IMNM. In recent years, IMNM has gained increasing attention and emerged as a research hotspot. Recent studies have suggested that the pathogenesis of IMNM is linked to aberrant activation of immune system, including immune responses mediated by antibodies, complement, and immune cells, particularly macrophages, as well as abnormal release of inflammatory factors. Non-immune mechanisms such as autophagy and endoplasmic reticulum stress also participate in this process. Additionally, genetic variations associated with IMNM have been identified, providing new insights into the genetic mechanisms of the disease. Progress has also been made in IMNM treatment research, including the use of immunosuppressants and the development of biologics. Despite the challenges in understanding the etiology and treatment of IMNM, the latest research findings offer important guidance and insights for delving deeper into the disease's pathogenic mechanisms and identifying new therapeutic strategies.

Immunogenicity of Extracellular Vesicles

Extracellular vesicles (EVs) are promising next-generation therapeutics and drug delivery systems due to demonstrated safety and efficacy in preclinical models and early-stage clinical trials. There is an urgent need to address the immunogenicity of EVs (beyond the apparent lack of immunotoxicity) to advance clinical development. To date, few studies have assessed unintended immunological recognition of EVs. An in-depth understanding of EV-induced immunogenicity and clearance is necessary to develop effective therapeutic strategies, including approaches to mitigate immunological recognition when undesired. This article summarizes various factors involved in the potential immunogenicity of EVs and strategies to reduce immunological recognition for improved therapeutic benefit.

Extracellular Vesicles in the Pathogenesis, Clinical Characterization, and Management of Dermatomyositis: A Narrative Review

Extracellular vesicles (EVs) are lipid-bilayer particles secreted from cells that primarily assist in cell-to-cell communication through the content of their cargo, such as proteins and RNA. EVs have been implicated in the pathogenesis of various autoimmune diseases, including dermatomyositis (DM), an inflammatory autoimmune disease characterized by distinct cutaneous manifestations, myopathy, and lung disease. We sought to review the role of EVs in DM and understand how they contribute to the pathogenesis and clinical characterization of the disease. We summarized the research progress on EVs in dermatomyositis based on recent publications. EV cargoes, such as double-stranded DNA, microRNA, and proteins, contribute to DM pathogenesis and mediate the proinflammatory response and cytokine release through signaling pathways such as the stimulator of interferon genes (STING) pathway. These nucleic acids and proteins have been proposed as disease-specific, stable biomarkers to monitor disease activity and responses to therapy. They also correlate with clinical parameters, inflammatory markers, and disease severity scores. Furthermore, some markers show an association with morbidities of DM, such as muscle weakness and interstitial lung disease. The continued study of EVs will help us to further elucidate our understanding of dermatomyositis.

Herbal supplement Spirulina stimulates inflammatory cytokine production in patients with dermatomyositis in vitro

Spirulina, an herbal supplement and popular ingredient in health foods, is a potent stimulant of the immune system. Spirulina use is temporally associated with the onset or exacerbation of Dermatomyositis (DM), an autoimmune connective tissue disease that frequently affects the skin and muscle. In this study, we investigated the effect of Spirulina on peripheral blood mononuclear cells (PBMCs) in DM and Healthy Controls (HCs), showing that Spirulina stimulates Interferon β (IFNβ), Tumor necrosis factor α (TNFα), and Interferon γ (IFNγ) production of DM PBMCs primarily via Toll-Like Receptor 4 (TLR4) activation using ELISA (enzyme linked immunosorbent assay) and flow cytometry. We show that classical monocytes and monocyte-derived dendritic cells are stimulated by Spirulina and are activated via TLR4. Skin from patients with Spirulina-associated DM exhibits an inflammatory milieu similar to that of idiopathic DM but with a stronger correlation of TLR4 and IFNγ.

Clinicopathological and circulating cell-free DNA profile in myositis associated with anti-mitochondrial antibody

OBJECTIVE

Anti-mitochondrial antibodies (AMAs) are associated with idiopathic inflammatory myopathies (IIMs). We aimed to summarize the clinicopathological characteristics, assess circulating cell-free mitochondrial DNA (ccf-mtDNA), and circulating cell-free nuclear DNA (ccf-nDNA) in AMA-associated IIMs.

METHODS

Medical records of 37 IIMs patients with AMAs were reviewed. Circulating cell-free mtDNA and ccf-nDNA levels in sera from IIMs patients with AMAs (n = 21), disease controls (n = 66) and healthy controls (HCs) (n = 23) were measured and compared. Twenty-eight immune-mediated necrotizing myopathy (IMNM) patients, 23 dermatomyositis (DM) patients, and 15 anti-synthetase syndrome (ASS) patients were enrolled as disease controls. Correlations between variables were analyzed.

RESULTS

Limb weakness was observed in 75.7% and neck weakness in 56.8% of patients. Cardiac involvement occurred in 51.4% of patients. Muscle pathology revealed 81.1% of IMNM, 5.4% polymyositis, and 13.5% nonspecific myositis. Microinfarction was observed in 8.1% of patients. Serum ccf-mtDNA levels in AMA-associated IIMs were significantly higher than those in HCs (p < 0.001), but no significant differences between AMA-associated IIMs and IMNM, DM, or ASS. Serum ccf-nDNA levels in AMA-associated IIMs were significantly higher than those in HCs (p = 0.02), and significantly lower than those in DM (p = 0.02). Serum ccf-nDNA levels correlated negatively with MMT8 total scores (rs = -0.458, p = 0.037) and positively with mRS scores (rs = 0.486, p = 0.025). Serum ccf-nDNA levels were significantly higher in the non-remission group (p < 0.01).

INTERPRETATION

AMA-associated IIMs exhibit distinct clinicopathological features. Serum ccf-nDNA may serve as a potential marker for disease severity and prognosis in AMA-associated IIMs.

Inhibition of Galectin-9 sensitizes tumors to anthracycline treatment via inducing antitumor immunity

Anthracyclines are a class of conventionally and routinely used first-line chemotherapy drugs for cancer treatment. In addition to the direct cytotoxic effects, increasing evidence indicates that the efficacy of the drugs also depends on immunomodulatory effects with unknown mechanisms. Galectin-9 (Gal-9), a member of the β-galactoside-binding protein family, has been demonstrated to induce T-cell death and promote immunosuppression in the tumor microenvironment. Here, we asked whether anthracycline-mediated immunomodulatory activity might be related to Gal-9. We found that combining doxorubicin with anti-Gal-9 therapy significantly inhibited tumor growth and prolonged overall survival in immune-competent syngeneic mouse models. Moreover, Gal-9 expression was increased in response to doxorubicin in various human and murine cancer cell lines. Mechanistically, doxorubicin induced tumoral Gal-9 by activating the STING/interferon β pathway. Clinically, Gal-9 and p-STING levels were elevated in the tumor tissues of breast cancer patients treated with anthracyclines. Our study demonstrates Gal-9 upregulation in response to anthracyclines as a novel mechanism mediating immune escape and suggests targeting Gal-9 in combination with anthracyclines as a promising therapeutic strategy for cancer treatment.

Endothelial Senescence and Its Impact on Angiogenesis in Alzheimer's Disease

Endothelial cells are constantly exposed to environmental stress factors that, above a certain threshold, trigger cellular senescence and apoptosis. The altered vascular function affects new vessel formation and endothelial fitness, contributing to the progression of age-related diseases. This narrative review highlights the complex interplay between senescence, oxidative stress, extracellular vesicles, and the extracellular matrix and emphasizes the crucial role of angiogenesis in aging and Alzheimer's disease. The interaction between the vascular and nervous systems is essential for the development of a healthy brain, especially since neurons are exceptionally dependent on nutrients carried by the blood. Therefore, anomalies in the delicate balance between pro- and antiangiogenic factors and the consequences of disrupted angiogenesis, such as misalignment, vascular leakage and disturbed blood flow, are responsible for neurodegeneration. The implications of altered non-productive angiogenesis in Alzheimer's disease due to dysregulated Delta-Notch and VEGF signaling are further explored. Additionally, potential therapeutic strategies such as exercise and caloric restriction to modulate angiogenesis and vascular aging and to mitigate the associated debilitating symptoms are discussed. Moreover, both the roles of extracellular vesicles in stress-induced senescence and as an early detection marker for Alzheimer's disease are considered. The intricate relationship between endothelial senescence and angiogenesis provides valuable insights into the mechanisms underlying angiogenesis-related disorders and opens avenues for future research and therapeutic interventions.

PCSK9 inhibition interrupts the cross-talk between keratinocytes and macrophages and prevents UVB-induced skin damage

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is an enzyme that promotes the degradation of low-density lipoprotein receptors. It is involved in hyperlipidemia as well as other diseases, such as cancer and skin inflammation. However, the detailed mechanism for PCSK9 on ultraviolet B (UVB)-induced skin lesions was not clear. Thus, the role and possible action mechanism of PCSK9 in UVB-induced skin damage in mice were studied here using siRNA and a small molecule inhibitor (SBC110736) against PCSK9. Immunohistochemical staining revealed a significant increase in PCSK9 expression after UVB exposure, indicating the possible role of PCSK9 in UVB damage. Skin damage, increase in epidermal thickness, and keratinocyte hyperproliferation were significantly alleviated after treatment with SBC110736 or siRNA duplexes, compared with that in the UVB model group. Notably, UVB exposure triggered DNA damage in keratinocytes, whereas substantial interferon regulatory factor 3 (IRF3) activation was observed in macrophages. Pharmacologic inhibition of STING or cGAS knockout significantly reduced UVB-induced damage. In the co-culture system, supernatant from UVB-treated keratinocyte induced IRF3 activation in macrophages. This activation was inhibited with SBC110736 and by PCSK9 knockdown. Collectively, our findings reveal that PCSK9 plays a critical role in the crosstalk between damaged keratinocytes and STING activation in macrophages. The interruption of this crosstalk by PCSK9 inhibition may be a potential therapeutic strategy for UVB-induced skin damage.

Topical Photodynamic Therapy Generates Bioactive Microvesicle Particles: Evidence for a Pathway Involved in Immunosuppressive Effects

Although effective in treating actinic damage, topical photodynamic therapy (PDT) has been shown to be immunosuppressive through unknown mechanisms, which could potentially limit its effectiveness. Multiple types of environmental stressors, including PDT, can produce the immunosuppressive lipid mediator platelet-activating factor (PAF). Because PAF can produce subcellular microvesicle particles (MVPs), these studies tested whether PDT can generate PAF and MVP release and whether these are involved in PDT-induced immunosuppression. Previously, topical PDT using blue light and 5-aminolevulinic acid was found to be a potent stimulus for PAF production in mice and human skin explants and human patients, and we show that experimental PDT also generates high levels of MVP. PDT-generated MVPs were independent of the PAF receptor but were dependent on the MVP-generating enzyme acid sphingomyelinase. Patients undergoing topical PDT treatment to at least 10% of body surface area showed local and systemic immunosuppression as measured by inhibition of delayed-type hypersensitivity reactions. Finally, using a murine model of contact hypersensitivity, PDT immunosuppression was blocked by genetic and pharmacologic inhibition of acid sphingomyelinase and genetic inhibition of PAF receptor signaling. These studies describe a mechanism involving MVP through which PDT exerts immunomodulatory effects, providing a potential target to improve its effectiveness.

Plasma proteomic profiling reveals KRT19 could be a potential biomarker in patients with anti-MDA5+ dermatomyositis

OBJECTIVE

To investigate the immune response-related protein profiling in plasma of patients with idiopathic inflammatory myopathies (IIMs), especially in anti-MDA5+ dermatomyositis (DM).

METHODS

A total of 166 IIM patients and 107 healthy controls (HCs) were enrolled in our study. Ninety-two plasma immune response-related proteins were detected by Olink proteomics in 36 IIM patients and 25 HCs. The expression of plasma KRT19 was validated in another 130 IIM patients, 82 HCs, and 55 other rheumatic diseases.

RESULTS

A total of 46 differentially expressed proteins were detected, including 12 upregulated proteins and 34 downregulated proteins in IIM patients compared with HCs. Pathway analysis revealed lactoferrin danger signal response pathway, TLR4 signaling and tolerance, infection, and IL-10 signaling pathway were activated. The immune response-related protein profiling significantly altered in anti-MDA5+ DM patients, with LAMP3, HSD11B1, and KRT19 significantly increased, while SH2D1A, ITGA11, TRIM21, CD28, ITGB6, and HEXIM1 tremendously decreased. In addition, KRT19 was significantly increased in IIM patients, especially in anti-MDA5+ DM patients with the diagnostic value of a significant area under the ROC curve of 0.881.

CONCLUSION

Immune response-related proteins are significantly altered in patients with anti-MDA5+ DM patients. KRT19 could be a potential biomarker for anti-MDA5+ DM patients. Key Points • What is already known on this topic? Anti-MDA5+ DM is a distinctive subtype of IIM. Plasma immune response-related proteins panel needs to be investigated. • What this study adds? Plasma protein profiling of immune response-related proteins significantly altered in patients with idiopathic inflammatory myopathies (IIM), especially in anti-MDA5+ DM patients. • How this study might affect research, practice, or policy? KRT19 could be a potential biomarker in patients with anti-MDA5+ dermatomyositis.

STAM transports STING oligomers into extracellular vesicles, down-regulating the innate immune response

Stimulator of interferon genes (STING) mediates the innate immune response against damaged endogenous double-strand DNA and exogenous virus infection. The location of STING is critical to the accurate control of defence signalling pathways. Recently, the effects of extracellular vesicles (EVs) in the regulation of innate immune signalling have been reported. Nevertheless, the particular roles played by STING in EVs and the related mechanisms have remained largely unknown. Herein, we report that when STING was activated in cells, EVs derived from these cells carried STING oligomers. Signal transducing adapter molecule 1 (STAM) was found to be a STING transporter that directly interacted with STING and facilitated STING transport into EVs. Importantly, the translocation of STING into EVs was a mechanism by which STING was degraded, suppressing the innate immune response. In summary, we elucidated the mechanism and function of the translocation of STING into EVs, adding to the understanding of STING activity regulation.

Vesicular traffic-mediated cell-to-cell signaling at the immune synapse in Ankylosing Spondylitis

The chronic inflammatory disease ankylosing spondylitis (AS) is marked by back discomfort, spinal ankylosis, and extra-articular symptoms. In AS, inflammation is responsible for both pain and spinal ankylosis. However, the processes that sustain chronic inflammation remain unknown. Despite the years of research conducted to decipher the intricacy of AS, little progress has been made in identifying the signaling events that lead to the development of this disease. T cells, an immune cell type that initiates and regulates the body's response to infection, have been established to substantially impact the development of AS. T lymphocytes are regarded as a crucial part of adaptive immunity for the control of the immune system. A highly coordinated interaction involving antigen-presenting cells (APCs) and T cells that regulate T cell activation constitutes an immunological synapse (IS). This first phase leads to the controlled trafficking of receptors and signaling mediators involved in folding endosomes to the cellular interface, which allows the transfer of information from T cells to APCs through IS formation. Discrimination of self and nonself antigen is somatically learned in adaptive immunity. In an autoimmune condition such as AS, there is a disturbance of self/nonself antigen discrimination; available findings imply that the IS plays a preeminent role in the adaptive immune response. In this paper, we provide insights into the genesis of AS by evaluating recent developments in the function of vesicular trafficking in IS formation and the targeted release of exosomes enriched microRNAs (miRNA) at the synaptic region in T cells.

The cGAS-STING pathway: Post-translational modifications and functional implications in diseases

Recent studies have illustrated the functional significance of DNA recognition in the activation of innate immune responses among a variety of diseases. The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway has been found to be modulated by post-translational modifications and can regulate the immune response via type I IFNs. Accumulating evidence indicates a pivotal role of cGAS-STING signaling, being protective or pathogenic, in the development of diseases. Thus, a comprehensive understanding of the post-translational modifications of cGAS-STING pathway and their role in disease development will provide insights in predicting individual disease outcomes and developing appropriate therapies. In this review, we will discuss the regulation of the cGAS-STING pathway and its implications in disease pathologies, as well as pharmacologic strategies to target the cGAS-STING pathway for therapeutic intervention.

DNA Containing Cyclobutane Pyrimidine Dimers Is Released from UVB-Irradiated Keratinocytes in a Caspase-Dependent Manner

Solar radiation induces the formation of cyclobutane pyrimidine dimers (CPDs) and other UV photoproducts in the genomic DNA of epidermal keratinocytes. Although CPDs have been detected in urine from UV- and sun-exposed individuals, the pathway by which they arrive there and the mechanisms by which UV-induced DNA damage in the skin has systemic effects throughout the body are not clear. Consistent with previous reports that DNA associates with small extracellular vesicles that are released from a variety of cell types, we observed that a small fraction of CPDs formed in genomic DNA after UVB exposure can later be detected in the culture medium. These extracellular CPDs are found within large fragments of histone-associated DNA and are released in a time- and UVB dose‒dependent manner. Moreover, studies with both cultured cells and human skin explants revealed that CPD release into the extracellular environment is blocked by caspase inhibition, which indicates a role for apoptotic signaling in CPD release from UVB-irradiated keratinocytes. Finally, we show that this released CPD-containing DNA can be taken up by other keratinocytes. These results therefore provide possible mechanisms for the export of damaged DNA from UVB-irradiated cells and for systemic effects of UVB exposure throughout the body.

New Perspectives on the Importance of Cell-Free DNA Biology

Body fluids are constantly replenished with a population of genetically diverse cell-free DNA (cfDNA) fragments, representing a vast reservoir of information reflecting real-time changes in the host and metagenome. As many body fluids can be collected non-invasively in a one-off and serial fashion, this reservoir can be tapped to develop assays for the diagnosis, prognosis, and monitoring of wide-ranging pathologies, such as solid tumors, fetal genetic abnormalities, rejected organ transplants, infections, and potentially many others. The translation of cfDNA research into useful clinical tests is gaining momentum, with recent progress being driven by rapidly evolving preanalytical and analytical procedures, integrated bioinformatics, and machine learning algorithms. Yet, despite these spectacular advances, cfDNA remains a very challenging analyte due to its immense heterogeneity and fluctuation in vivo. It is increasingly recognized that high-fidelity reconstruction of the information stored in cfDNA, and in turn the development of tests that are fit for clinical roll-out, requires a much deeper understanding of both the physico-chemical features of cfDNA and the biological, physiological, lifestyle, and environmental factors that modulate it. This is a daunting task, but with significant upsides. In this review we showed how expanded knowledge on cfDNA biology and faithful reverse-engineering of cfDNA samples promises to (i) augment the sensitivity and specificity of existing cfDNA assays; (ii) expand the repertoire of disease-specific cfDNA markers, thereby leading to the development of increasingly powerful assays; (iii) reshape personal molecular medicine; and (iv) have an unprecedented impact on genetics research.

The roles of extracellular vesicles in the immune system

The twenty-first century has witnessed major developments in the field of extracellular vesicle (EV) research, including significant steps towards defining standard criteria for the separation and detection of EVs. The recent recognition that EVs have the potential to function as biomarkers or as therapeutic tools has attracted even greater attention to their study. With this progress in mind, an updated comprehensive overview of the roles of EVs in the immune system is timely. This Review summarizes the roles of EVs in basic processes of innate and adaptive immunity, including inflammation, antigen presentation, and the development and activation of B cells and T cells. It also highlights key progress related to deciphering the roles of EVs in antimicrobial defence and in allergic, autoimmune and antitumour immune responses. It ends with a focus on the relevance of EVs to immunotherapy and vaccination, drawing attention to ongoing or recently completed clinical trials that aim to harness the therapeutic potential of EVs.

Dysregulation of the cGAS-STING Pathway in Monogenic Autoinflammation and Lupus

One of the oldest mechanisms of immune defense against pathogens is through detection of foreign DNA. Since human DNA is compartmentalized into the nucleus, its presence in the cytosol heralds a potential threat. The cGAS-STING pathway is one of the most important cytosolic DNA sensing pathways and leads to interferon signaling, inflammasome activation, autophagy, and cell death. While STING signaling is protective at physiologic levels, chronic activation of this pathway can instead drive autoinflammation and autoimmunity. Here we discuss several monogenic disorders of the STING pathway that highlight its impact on both innate and adaptive immunity in the progressive loss of tolerance. The potential relevance of STING signaling in systemic lupus erythematosus is then discussed with a focus on future avenues for monitoring and targeting this pathway.

Lung Inflammation in STING-Associated Vasculopathy with Onset in Infancy (SAVI)

STING-associated vasculopathy with onset in infancy (SAVI) is a type I interferonopathy caused by gain-of-function mutations in STING1 encoding stimulator of interferon genes (STING) protein. SAVI is characterized by severe inflammatory lung disease, a feature not observed in previously described type I interferonopathies i.e., Mendelian autoinflammatory disorders defined by constitutive activation of the type I interferon (IFN) pathway. Molecular defects in nucleic acid metabolism or sensing are central to the pathophysiology of these diseases, with such defects occurring at any step of the tightly regulated pathway of type I IFN production and signaling (e.g., exonuclease loss of function, RNA-DNA hybrid accumulation, constitutive activation of adaptor proteins such as STING). Among over 30 genotypes, SAVI and COPA syndrome, whose pathophysiology was recently linked to a constitutive activation of STING signaling, are the only type I interferonopathies presenting with predominant lung involvement. Lung disease is the leading cause of morbidity and mortality in these two disorders which do not respond to conventional immunosuppressive therapies and only partially to JAK1/2 inhibitors. In human silicosis, STING-dependent sensing of self-DNA following cell death triggered by silica exposure has been found to drive lung inflammation in mice and human models. These recent findings support a key role for STING and nucleic acid sensing in the homeostasis of intrinsic pulmonary inflammation. However, mechanisms by which monogenic defects in the STING pathway lead to pulmonary damages are not yet fully elucidated, and an improved understanding of such mechanisms is fundamental to improved future patient management. Here, we review the recent insights into the pathophysiology of SAVI and outline our current understanding of self-nucleic acid-mediated lung inflammation in humans.

STING Signaling and Skin Cancers

Recent developments in immunotherapy against malignancies overcome the disadvantages of traditional systemic treatments; however, this immune checkpoint treatment is not perfect and cannot obtain a satisfactory clinical outcome in all cases. Therefore, an additional therapeutic option for malignancy is needed in oncology. Stimulator of interferon genes (STING) has recently been highlighted as a strong type I interferon driver and shows anti-tumor immunity against various malignancies. STING-targeted anti-tumor immunotherapy is expected to enhance the anti-tumor effects and clinical outcomes of immunotherapy against malignancies. In this review, we focus on recent advancements in the knowledge gained from research on STING signaling in skin cancers. In addition to the limitations of STING-targeted immunotherapy, we also discuss the clinical application of STING agonists in the treatment of skin cancer.

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.