Immunomodulation by endothelial cells - partnering up with the immune system?

Functional analysis of antigen presentation by enteric glial cells during intestinal inflammation

The Enteric Nervous System is composed of a vastly interconnected network of neurons and glial cells that coordinate to regulate homeostatic gut function including intestinal motility, nutrient sensing, and mucosal barrier immunity. Enteric Glial Cells (EGCs) are a heterogeneous cell population located throughout the gastrointestinal tract and have well described roles in regulating intestinal immune responses. Enteric Glial Cells have been suggested to act as nonconventional antigen presenting cells via the Major Histocompatibility Complex II (MHC II), though this has not been confirmed functionally. Here, we investigate the capability of EGCs to present antigen on MHC I and MHC II using in vitro antigen presentation assays performed with primary murine EGC cultures. We found that EGCs are capable of functional antigen presentation on MHC I, including antigen cross-presentation, but are not capable of functional antigen presentation on MHC II. We also determined EGC cell surface MHC I and MHC II expression levels by flow cytometry during intestinal inflammation during Dextran Sodium Sulfate-induced colitis or acute Toxoplasma gondii infection. We found that EGCs upregulate MHC I during acute T. gondii infection and induce low-level MHC II expression. These findings suggest that EGCs may be important in the regulation of CD8+ T cell responses via MHC I mediated antigen (cross) presentation but may not be relevant for MHC II-mediated antigen presentation.

Tertiary Lymphoid Structures in Central Nervous System Disorders

The central nervous system (CNS) constitutes a tightly regulated milieu, where immune responses are strictly controlled to prevent neurological damage. This poses considerable challenges to the therapeutic management of CNS pathologies, such as autoimmune disorders and cancer. Tertiary lymphoid structures (TLS) are ectopic, lymph node-like structures containing B- and T-cells, often associated with chronic inflammation or cancer, which have been shown to be detrimental in autoimmunity but beneficial in cancer. In-depth studies of TLS induction in CNS disorders, as well as their precise role in regulating adaptive immune responses in this context, will be paramount to the development of novel TLS-targeting therapies. In the present chapter, we review the anatomical and physiological peculiarities shaping TLS formation in the CNS, their relevance in autoimmunity and cancer, as well as their implications for the development of novel therapeutic modalities for these patients.

Convergent inducers and effectors of T cell paralysis in the tumour microenvironment

Tumorigenesis embodies the formation of a heterotypic tumour microenvironment (TME) that, among its many functions, enables the evasion of T cell-mediated immune responses. Remarkably, most TME cell types, including cancer cells, fibroblasts, myeloid cells, vascular endothelial cells and pericytes, can be stimulated to deploy immunoregulatory programmes. These programmes involve regulatory inducers (signals-in) and functional effectors (signals-out) that impair CD8+ and CD4+ T cell activity through cytokines, growth factors, immune checkpoints and metabolites. Some signals target specific cell types, whereas others, such as transforming growth factor-β (TGFβ) and prostaglandin E2 (PGE2), exert broad, pleiotropic effects; as signals-in, they trigger immunosuppressive programmes in most TME cell types, and as signals-out, they directly inhibit T cells and also modulate other cells to reinforce immunosuppression. This functional diversity and redundancy pose a challenge for therapeutic targeting of the immune-evasive TME. Fundamentally, the commonality of regulatory programmes aimed at abrogating T cell activity, along with paracrine signalling between cells of the TME, suggests that many normal cell types are hard-wired with latent functions that can be triggered to prevent inappropriate immune attack. This intrinsic capability is evidently co-opted throughout the TME, enabling tumours to evade immune destruction.

Induction of protective immune responses at respiratory mucosal sites

Many pathogens enter the host through mucosal sites. Thus, interfering with pathogen entry through local neutralization at mucosal sites therefore is an effective strategy for preventing disease. Mucosally administered vaccines have the potential to induce protective immune responses at mucosal sites. This manuscript delves into some of the latest developments in mucosal vaccination, particularly focusing on advancements in adjuvant technologies and the role of these adjuvants in enhancing vaccine efficacy against respiratory pathogens. It highlights the anatomical and immunological complexities of the respiratory mucosal immune system, emphasizing the significance of mucosal secretory IgA and tissue-resident memory T cells in local immune responses. We further discuss the differences between immune responses induced through traditional parenteral vaccination approaches vs. mucosal administration strategies, and explore the protective advantages offered by immunization through mucosal routes.

Encompassing view of spatial and single-cell RNA sequencing renews the role of the microvasculature in human atherosclerosis

Atherosclerosis is a pervasive contributor to ischemic heart disease and stroke. Despite the advance of lipid-lowering therapies and anti-hypertensive agents, the residual risk of an atherosclerotic event remains high, and developing therapeutic strategies has proven challenging. This is due to the complexity of atherosclerosis with a spatial interplay of multiple cell types within the vascular wall. In this study, we generated an integrative high-resolution map of human atherosclerotic plaques combining single-cell RNA sequencing from multiple studies and spatial transcriptomics data from 12 human specimens with different stages of atherosclerosis. Here we show cell-type-specific and atherosclerosis-specific expression changes and spatially constrained alterations in cell-cell communication. We highlight the possible recruitment of lymphocytes via ACKR1 endothelial cells of the vasa vasorum, the migration of vascular smooth muscle cells toward the lumen by transforming into fibromyocytes and cell-cell communication in the plaque region, indicating an intricate cellular interplay within the adventitia and the subendothelial space in human atherosclerosis.

Recent advancement in the spatial immuno-oncology

Recent advancements in spatial transcriptomics and spatial proteomics enabled the high-throughput profiling of single or multi-cell types and cell states with spatial information. They transformed our understanding of the higher-order architectures and paired cell-cell interactions within a tumor microenvironment (TME). Within less than a decade, this rapidly emerging field has discovered much crucial fundamental knowledge and significantly improved clinical diagnosis in the field of immuno-oncology. This review summarizes the conceptual frameworks to understand spatial omics data and highlights the updated knowledge of spatial immuno-oncology.

Toxicity of size separated chrysotile fibres: The relevance of the macrophage-endothelial axis crosstalk

Asbestos minerals have been widely exploited due to their physical-chemical properties, and chrysotile asbestos has accounted for about 95% of all asbestos commercially employed worldwide. The exposure to chrysotile, classified like other five amphibole asbestos species as carcinogenic to humans, represents a serious occupational and environmental hazard. Nevertheless, this mineral is still largely employed in about 65% of the countries worldwide, which still allow its "safe use". The complex mechanisms through which the mineral fibres induce toxicity are not yet completely understood. In this regard, the morphometric parameters of asbestos fibres (e.g., length, width, aspect ratio) are known for their fundamental role in determining the degree of pathogenicity. In this context, the potential toxicity of short chrysotile fibres remains widely debated due to the contradictory results from countless studies. Thus, the present study investigated the different toxicity mechanisms of two representative batches of short (length ≤5 µm) and long (length >5 µm) chrysotile fibres obtained by cryogenic milling. The fibre doses were based upon equal mass and size, since due to chrysotile ability to form bundles, it was not possible to calculate the number of fibers applied per cell. The cytotoxic, genotoxic, and pro-inflammatory potential of the two size-separated chrysotile fractions was investigated on human THP-1-derived macrophages and HECV endothelial cells, both separately and in a co-culture setup, mimicking the alveolar pro-inflammatory microenvironment, in time course experiments up to 1 week. Both chrysotile fractions displayed cytotoxic, genotoxic, and pro-inflammatory effects, with results comparable to the well-known damaging effects of crocidolite asbestos, or higher, as in the case of the longer chrysotile fraction. Furthermore, in presence of HECV, fibre-treated macrophages showed prolonged inflammation, indicating an interesting crosstalk between these cells able to sustain a low-grade chronic inflammation in the lung. In conclusion, these results help to shed light on some important open questions on the mechanisms of toxicity of chrysotile asbestos fibres.

Packaged release and targeted delivery of cytokines by migrasomes in circulation

In dynamic systems like the circulatory system, establishing localized cytokine gradients is challenging. Upon lipopolysaccharide (LPS) stimulation, we observed that monocytes release numerous migrasomes enriched with inflammatory cytokines, such as TNF-α and IL-6. These cytokines are transported into migrasomes via secretory carriers, leading to their immediate exocytosis or eventual release from detached migrasomes. We successfully isolated TNF-α and IL-6-enriched, monocyte-derived migrasomes from the blood of LPS-treated mice. Total secretion analysis revealed a substantial amount of TNF-α and IL-6 released in a migrasome-packaged form. Thus, detached, monocyte-derived migrasomes represent a type of extracellular vesicle highly enriched with cytokines. Physiologically, these cytokine-laden migrasomes rapidly accumulate at local sites of inflammation, effectively creating a concentrated source of cytokines. Our research uncovers novel mechanisms for cytokine release and delivery, providing new insights into immune response modulation.

Human iPSC-Derived Endothelial Cells Exhibit Reduced Immunogenicity in Comparison With Human Primary Endothelial Cells

Human induced pluripotent stem cell (iPSC)-derived endothelial cells (ECs) have emerged as a promising source of autologous cells with great potential to produce novel cell therapy for ischemic vascular diseases. However, their clinical application still faces numerous challenges including safety concerns such as the potential aberrant immunogenicity derived from the reprogramming process. This study investigated immunological phenotypes of iPSC-ECs by a side-by-side comparison with primary human umbilical vein ECs (HUVECs). Three types of human iPSC-ECs, NIBSC8-EC generated in house and two commercial iPSC-ECs, alongside HUVECs, were examined for surface expression of proteins of immune relevance under resting conditions and after cytokine activation. All iPSC-EC populations failed to express major histocompatibility complex (MHC) Class II on their surface following interferon-gamma (IFN-γ) treatment but showed similar basal and IFN-γ-stimulated expression levels of MHC Class I of HUVECs. Multiple iPSC-ECs also retained constitutive and tumor necrosis factor-alpha (TNF-α)-stimulated expression levels of intercellular adhesion molecule-1 (ICAM-1) like HUVECs. However, TNF-α induced a differential expression of E-selectin and vascular cell adhesion molecule-1 (VCAM-1) on iPSC-ECs. Furthermore, real-time monitoring of proliferation of human peripheral blood mononuclear cells (PBMCs) cocultured on an endothelial monolayer over 5 days showed that iPSC-ECs provoked distinct dynamics of PBMC proliferation, which was generally decreased in alloreactivity and IFN-γ-stimulated proliferation of PBMCs compared with HUVECs. Consistently, in the conventional mixed lymphocyte reaction (MLR), the proliferation of total CD3+ and CD4+ T cells after 5-day cocultures with multiple iPSC-EC populations was largely reduced compared to HUVECs. Last, multiple iPSC-EC cocultures secreted lower levels of proinflammatory cytokines than HUVEC cocultures. Collectively, iPSC-ECs manifested many similarities, but also some disparities with a generally weaker inflammatory immune response than primary ECs, indicating that iPSC-ECs may possibly exhibit hypoimmunogenicity corresponding with less risk of immune rejection in a transplant setting, which is important for safe and effective cell therapies.

Molecular signature-based labeling techniques for vascular endothelial cells

Vascular endothelial cells (VECs) play a crucial role in the development and maintenance of vascular biology specific to the tissue types. Molecular signature-based labeling and imaging of VECs help researchers understand potential mechanisms linking VECs to disease pathology, serving as valuable biomarkers in clinical settings and trials. Labeling techniques involve selectively tagging or marking VECs for visualization. Immunolabeled employs antibodies that specifically bind to VECs markers, while fluorescent tracers or dyes can directly label VECs for imaging. Some techniques use specific carbohydrate residues on cell surface, while others employ endothelial-specific promoters to express fluorescent proteins. Additionally, VEC can be labeled with contrast agents, radiolabeled tracers, and nanoparticles. The choice of labeling technique depends on study context, including whether it involves animal models, in vitro cell cultures, or clinical applications. Herein, we discussed the various labeling methods utilized to label VECs and the techniques to visualize them.

Effect of endothelial responses on sepsis-associated organ dysfunction

ABSTRACT

Sepsis-related organ dysfunction is associated with increased morbidity and mortality. Previous studies have found that the endothelium plays crucial roles in maintaining the vascular permeability during sepsis, as well as in regulating inflammation and thrombosis. During sepsis, endothelial cells may release cytokines, chemokines, and pro-coagulant factors, as well as express adhesion molecules. In general, endothelial responses during sepsis typically inhibit bacterial transmission and coordinate leukocyte recruitment to promote bacterial clearance. However, excessive or prolonged endothelial activation can lead to impaired microcirculation, tissue hypoperfusion, and organ dysfunction. Given the structural and functional heterogeneity of endothelial cells in different organs, there are potential differences in endothelial responses by organ type, and the risk of organ damage may vary accordingly. This article reviews the endothelial response observed in sepsis and its effects on organ function, summarizes current progress in the development of therapeutic interventions targeting the endothelial response, and discusses future research directions to serve as a reference for researchers in the field.

Host defense peptides at the crossroad of endothelial cell physiology: Insight into mechanistic and pharmacological implications

Antimicrobial peptides (AMPs), particularly host defense peptides (HDPs), have gained recognition for their role in host defense mechanisms, but they have also shown potential as a promising anticancer, antiviral, antiparasitic, antifungal and immunomodulatory agent. Research studies in recent years have shown HDPs play a crucial role in endothelial cell function and biology. The function of endothelial cells is impacted by HDPs' complex interplay between cytoprotective and cytotoxic actions as they are known to modulate barrier integrity, inflammatory response and angiogenesis. This biphasic response varies and depends on the peptide structure, its concentration, and the microenvironment. These effects are mediated through key signaling pathways, including MAPK, NF-κB, and PI3K/Akt, which controls responses such as cell proliferation, apoptosis, and migration. In the present review, we have discussed the significance of the intriguing relationship between HDPs and endothelial cell physiology which suggests it potential as a therapeutic agents for the treating wounds, cardiovascular diseases, and inflammation-related endothelial damage.

Lymphocytes and innate immune cells in acute kidney injury and repair

Acute kidney injury (AKI) is a common and serious disease entity that affects native kidneys and allografts but for which no specific treatments exist. Complex intrarenal inflammatory processes driven by lymphocytes and innate immune cells have key roles in the development and progression of AKI. Many studies have focused on prevention of early injury in AKI. However, most patients with AKI present after injury is already established. Increasing research is therefore focusing on mechanisms of renal repair following AKI and prevention of progression from AKI to chronic kidney disease. CD4+ and CD8+ T cells, B cells and neutrophils are probably involved in the development and progression of AKI, whereas regulatory T cells, double-negative T cells and type 2 innate lymphoid cells have protective roles. Several immune cells, such as macrophages and natural killer T cells, can have both deleterious and protective effects, depending on their subtype and/or the stage of AKI. The immune system not only participates in injury and repair processes during AKI but also has a role in mediating AKI-induced distant organ dysfunction. Targeted manipulation of immune cells is a promising therapeutic strategy to improve AKI outcomes.

The transcriptional repressor B cell lymphoma 6 regulates CXCR3 chemokine and human leukocyte antigen II expression in endothelial cells

Interferon gamma (IFN-γ) induces an endothelial proimmunogenic phenotype through the JAK/STAT1 pathway, which can shape the activation of alloreactive leukocytes in transplant rejection. In immune cells, the DNA-binding protein B cell lymphoma 6 (BCL6) controls the transcription of inflammatory genes. This study tested if BCL6 modulates IFN-γ-induced gene expression in endothelial cells. In vitro, BCL6 was IFN-γ-inducible in primary human endothelium, along with CXCR3 chemokines and human leukocyte antigen (HLA). BCL6, HLA II, and CXCL9 were also increased in human cardiac transplants during acute rejection. Knockdown of BCL6 augmented, whereas overexpression and BTB domain inhibitors (BCL6-BTBi) suppressed, HLA II and CXCR3 chemokine expression but not HLA I. Further, BCL6 had a greater effect on HLA-DR and DP but was less involved in regulating HLA-DQ expression. The effect correlated with BCL6 binding motifs in or near affected genes. The BCL6 DNA recognition sequence was highly similar to that of STAT1, and BTBi reduced STAT1's transcriptional activity in vitro. Our results show for the first time that BCL6 selectively controls IFN-γ-induced endothelial gene expression, advancing our understanding of the endogenous mechanisms regulating donor immunogenicity.

Epidermal stem cells: Interplay with the skin microenvironment during wound healing

Skin undergoes everyday turnover while often challenged by injuries. The wound healing process in the skin is a dynamic sequence of events that involves various cell types and signaling pathways. Epidermal stem cells (EpdSCs), the tissue-resident stem cells in the skin tissue, are at the center of this complicated process due to their special ability to self-renew and differentiate. During this process, EpdSCs interact actively with the tissue microenvironment, which is essential for proper re-epithelialization and skin barrier restoration. This review describes the intricate interplays between EpdSCs and various components of their surroundings, including extracellular matrix/fibroblasts, vasculature/endothelial cells, and immune cells, as well as their roles in tissue repair.

Bone marrow mesenchymal stem cells-derived exosomal miR-381 alleviates lung ischemia-reperfusion injury by activating Treg differentiation through inhibiting YTHDF1 expression

AIM

Our study aimed to investigate whether BMSCs-derived exosomal miR-381 promotes Treg cell differentiation in lung ischemia-reperfusion injury (LIRI), and the underlying mechanism.

METHODS

The in vitro and in vivo models of LIRI were established by hypoxia/reoxygenation (H/R) treatment and lung ischemia/reperfusion (I/R) surgery, respectively. BMSCs-derived exosomes were isolated and identified by western blot, nanoparticle tracking analysis, and transmission electron microscopy. Cell viability, proliferation, and apoptosis were assessed by CCK-8, EdU, and flow cytometry assay, respectively. IL-18 secretion level in lung microvascular endothelial cells (LMECs) and lung tissue homogenate was examined by ELISA. Treg cell differentiation was determined using flow cytometry. The relationships between miR-381, YTHDF1, and IL-18 were investigated using dual-luciferase reporter gene, RIP, and/or RNA pull-down assays. MeRIP assay was employed to determine m6A modification of IL-18 mRNA in LMECs. The ubiquitination level of Foxp3 protein in CD4+ T cells was analyzed by Co-IP assay.

RESULTS

BMSCs-derived exosomes reduced LMECs injury and increased Treg cell differentiation in LIRI, whereas miR-381 inhibition in BMSCs weakened these impacts. Mechanistically, miR-381 inhibited IL-18 translation in LMECs by inhibiting YTHDF1 expression via binding to its 3'-UTR. As expected, YTHDF1 overexpression in LMECs abolished the effects of miR-381-overexpressed exosomes on LMECs injury and Treg cell differentiation. Moreover, LMECs-secreted IL-18 inhibited Treg cell differentiation by promoting the ubiquitination degradation of Foxp3 protein.

CONCLUSION

BMSCs-derived exosomal miR-381 suppressed IL-18 translation in LMECs through binding to YTHDF1 3'-UTR, thus suppressing the ubiquitination degradation of Foxp3 in CD4+ T cells, which promoted Treg cell differentiation and mitigated LIRI development.

Light-based 3D bioprinting techniques for illuminating the advances of vascular tissue engineering

Vascular tissue engineering faces significant challenges in creating in vitro vascular disease models, implantable vascular grafts, and vascularized tissue/organ constructs due to limitations in manufacturing precision, structural complexity, replicating the composited architecture, and mimicking the mechanical properties of natural vessels. Light-based 3D bioprinting, leveraging the unique advantages of light including high resolution, rapid curing, multi-material adaptability, and tunable photochemistry, offers transformative solutions to these obstacles. With the emergence of diverse light-based 3D bioprinting techniques and innovative strategies, the advances in vascular tissue engineering have been significantly accelerated. This review provides an overview of the human vascular system and its physiological functions, followed by an in-depth discussion of advancements in light-based 3D bioprinting, including light-dominated and light-assisted techniques. We explore the application of these technologies in vascular tissue engineering for creating in vitro vascular disease models recapitulating key pathological features, implantable blood vessel grafts, and tissue analogs with the integration of capillary-like vasculatures. Finally, we provide readers with insights into the future perspectives of light-based 3D bioprinting to revolutionize vascular tissue engineering.

The roles of extracellular vesicles in gliomas: Challenge or opportunity?

Gliomas are increasingly becoming a major disease affecting human health, and current treatments are not as effective as expected. Deeper insights into glioma heterogeneity and the search for new diagnostic and therapeutic strategies appear to be urgent. Gliomas adapt to their surroundings and form a supportive tumor microenvironment (TME). Glioma cells will communicate with the surrounding cells through extracellular vesicles (EVs) carrying bioactive substances such as nucleic acids, proteins and lipids which is related to the modification to various metabolic pathways and regulation of biological behaviors, and this regulation can be bidirectional, widely existing between cells in the TME, constituting a complex network of interactions. This complex regulation can affect glioma therapy, leading to different types of resistance. Because of the feasibility of EVs isolation in various body fluids, they have a promising usage in the diagnosis and monitoring of gliomas. At the same time, the nature of EVs to cross the blood-brain barrier (BBB) confers potential for their use as drug delivery systems. In this review, we will focus on the roles and functions of EVs derived from different cellular origins in the glioma microenvironment and the intercellular regulatory networks, and explore possible clinical applications in glioma diagnosis and precision therapy.

Sele-targeted siRNA liposome nanoparticles inhibit pathological scars formation via blocking the cross-talk between monocyte and endothelial cells: a preclinical study based on a novel mice scar model

BACKGROUND

Pathological scars (PS) are one of the most common complications in patients with trauma and burns, leading to functional impairments and aesthetic concerns. Mechanical tension at injury sites is a crucial factor in PS formation. However, the precise mechanisms remain unclear due to the lack of reliable animal models.

RESULTS

We developed a novel mouse model, the Retroflex Scar Model (RSM), which induces PS by applying controlled tension to wounds in vivo. RNA sequencing identified significant transcriptome changes in RSM-induced scars. Elevated expression of E-Selectin (Sele) was observed in endothelial cells from both the RSM model and human PS (Keloid) samples. In vitro studies demonstrated that cyclic mechanical stretching (CMS) increased Sele expression, promoting monocyte adhesion and the release of pro-inflammatory factors. Single-cell sequencing analysis from the GEO database, complemented by Western blotting, immunofluorescence, and co-immunoprecipitation, confirmed the role of Sele-mediated monocyte adhesion in PS formation. Additionally, we developed Sele-targeted siRNA liposome nanoparticles (LNPs) to inhibit monocyte adhesion. Intradermal administration of these LNPs effectively reduced PS formation in both in vivo and in vitro studies.

CONCLUSIONS

This study successfully established a reliable mouse model for PS, highlighting the significant roles of mechanical tension and chronic inflammation in PS formation. We identified Sele as a key therapeutic target and developed Sele-targeted siRNA LNPs, which demonstrated potential as a preventive strategy for PS. These findings provide valuable insights into PS pathogenesis and open new avenues for developing effective treatments for pathological scars.

Endothelial RIPK3 minimizes organotypic inflammation and vascular permeability in ischemia-reperfusion injury

Recent studies have revealed a link between endothelial receptor-interacting protein kinase 3 (RIPK3) and vascular integrity. During mouse embryonic development, hypoxia can trigger elevated endothelial RIPK3 that contributes to lethal vascular rupture. However, it is unknown whether RIPK3 regulate endothelial barrier function in adult vasculature under hypoxic injury conditions such as ischemia-reperfusion (I/R) injury. Here we performed inducible genetic deletion of endothelial Ripk3 ( Ripk iECKO ) in mice, which led to elevated vascular permeability in the small intestine and multiple distal organs after intestinal I/R injury. Mechanistically, this vascular permeability correlated with increased endothelial secretion of IL-6 and organ-specific expression of VCAM-1 and ICAM-1 adhesion molecules. Circulating monocyte depletion with clodronate liposomes reduced permeability in organs with elevated adhesion molecules, highlighting the contribution of monocyte adhesion and extravasation to Ripk iECKO barrier dysfunction. These results elucidate mechanisms by which RIPK3 regulates endothelial inflammation to minimize vascular permeability in I/R injury.

GRAPHICAL ABSTRACT

The adaptive immune system in the retina of diabetics

As the prevalence of diabetes mellitus increases each year, its most common microvascular complication, diabetic retinopathy (DR), is also on the rise. DR is now regarded as an inflammatory disease in which innate immunity plays a crucial role, and a large number of innate immune cells with associated cytokines are involved in the pathologic process of DR. The role of adaptive immunity in DR is seldom mentioned, probably due to the general perception of the immune privileged environment of the retina; however, in recent years there has been a gradual increase in research on the role of adaptive immunity in DR, and with the discovery of the retinal lymphatic system, it seems that the role of adaptive immunity can no longer be ignored. Here, we discuss the immunosuppressive environment of the retina, the phenomenon and potential mechanisms of lymphocyte infiltration in DR, and the role of the adaptive immune system in the diabetic retina, which may point the way for future research.

The Role of Microglia and Astrocytes in the Pathomechanism of Neuroinflammation in Parkinson's Disease-Focus on Alpha-Synuclein

Glial cells, including astrocytes and microglia, are pivotal in maintaining central nervous system (CNS) homeostasis and responding to pathological insults. This review elucidates the complex immunomodulatory functions of glial cells, with a particular focus on their involvement in inflammation cascades initiated by the accumulation of alpha-synuclein (α-syn), a hallmark of Parkinson's disease (PD). Deriving insights from studies on both sporadic and familial forms of PD, as well as animal models of PD, we explore how glial cells contribute to the progression of inflammation triggered by α-syn aggregation. Additionally, we analyze the interplay between glial cells and the blood-brain barrier (BBB), highlighting the role of these cells in maintaining BBB integrity and permeability in the context of PD pathology. Furthermore, we delve into the potential activation of repair and neuroprotective mechanisms mediated by glial cells amidst α-syn-induced neuroinflammation. By integrating information on sporadic and familial PD, as well as BBB dynamics, this review aims to deepen our understanding of the multifaceted interactions between glial cells, α-syn pathology, and CNS inflammation, thereby offering valuable insights into therapeutic strategies for PD and related neurodegenerative disorders.

The roles of cancer stem cells and therapeutic implications in melanoma

Melanoma is a highly malignant skin tumor characterized by high metastasis and poor prognosis. Recent studies have highlighted the pivotal role of melanoma stem cells (MSCs)-a subpopulation of cancer stem cells (CSCs)-in driving tumor growth, metastasis, therapeutic resistance, and recurrence. Similar to CSCs in other cancers, MSCs possess unique characteristics, including specific surface markers, dysregulated signaling pathways, and the ability to thrive within complex tumor microenvironment (TME). This review explored the current landscape of MSC research, discussing the identification of MSC-specific surface markers, the role of key signaling pathways such as Wnt/β-catenin, Notch, and Hedgehog (Hh), and how interactions within the TME, including hypoxia and immune cells, contribute to MSC-mediated drug resistance and metastatic behavior. Furthermore, we also investigated the latest therapeutic strategies targeting MSCs, such as small-molecule inhibitors, immune-based approaches, and novel vaccine developments, with an emphasis on their potential to overcome melanoma progression and improve clinical outcomes. This review aims to provide valuable insights into the complex roles of MSCs in melanoma biology and offers perspectives for future research and therapeutic advances against this challenging disease.

A systematic review and meta-analysis of the endothelial-immune candidate biomarker endoglin in rheumatic diseases

Existing challenges in accurately diagnosing various rheumatic diseases (RDs) have stimulated the search for novel biomarkers to aid clinical evaluation and monitoring. We conducted a systematic review and meta-analysis of studies investigating the candidate biomarker endoglin (CD105), a transmembrane glycoprotein expressed in endothelial, myeloid, and lymphoid cells, in RD patients and healthy controls. We searched PubMed, Scopus, and Web of Science from inception to 10 August 2024 to identify relevant studies. We evaluated the risk of bias using the JBI Critical Appraisal Checklist and the certainty of evidence using GRADE (PROSPERO registration number: CRD42023581008). Overall, circulating endoglin concentrations were significantly higher in RD patients compared to controls (13 studies; standard mean difference, SMD = 0.64, 95% CI 0.13 to 1.14, p = 0.014; low certainty of evidence). The effect size of the between-group differences in endoglin concentrations was not significantly associated with age, male-to-female ratio, year of publication, number of participants, or mean RD duration. By contrast, the effect size was statistically significant in studies conducted in the European region (p = 0.033), involving patients with systemic sclerosis (p = 0.032), and measuring serum (p = 0.019). The results of this systematic review and meta-analysis suggest the potential pathophysiological role of endoglin in RDs. This, however, requires further investigation in prospective studies, particularly in patients with systemic sclerosis.

Endothelial metabolic control of insulin sensitivity through resident macrophages

Endothelial cells (ECs) not only form passive blood conduits but actively contribute to nutrient transport and organ homeostasis. The role of ECs in glucose homeostasis is, however, poorly understood. Here, we show that, in skeletal muscle, endothelial glucose transporter 1 (Glut1/Slc2a1) controls glucose uptake via vascular metabolic control of muscle-resident macrophages without affecting transendothelial glucose transport. Lowering endothelial Glut1 via genetic depletion (Glut1ΔEC) or upon a short-term high-fat diet increased angiocrine osteopontin (OPN/Spp1) secretion. This promoted resident muscle macrophage activation and proliferation, which impaired muscle insulin sensitivity. Consequently, co-deleting Spp1 from ECs prevented macrophage accumulation and improved insulin sensitivity in Glut1ΔEC mice. Mechanistically, Glut1-dependent endothelial glucose metabolic rewiring increased OPN in a serine metabolism-dependent fashion. Our data illustrate how the glycolytic endothelium creates a microenvironment that controls resident muscle macrophage phenotype and function and directly links resident muscle macrophages to the maintenance of muscle glucose homeostasis.

Tailored endothelialization enabled by engineered endothelial cell vesicles accelerates remodeling of small-diameter vascular grafts

Current gold standard for the replacement of small-diameter blood vessel (ID < 4 mm) is still to utilize the autologous vessels of patients due to the limitations of small-diameter vascular grafts (SDVG) on weak endothelialization, intimal hyperplasia and low patency. Herein, we create the SDVG with the tailored endothelialization by applying the engineered endothelial cell vesicles to camouflaging vascular grafts for the enhancement of vascular remodeling. The engineered endothelial cell vesicles were modified with azide groups (ECVs-N3) through metabolic glycoengineering to precisely link the vascular graft made of PCL-DBCO via click chemistry, and thus fabricating ECVG (ECVs-N3 modified SDVG), which assists inhibition of platelet adhesion and activation, promotion of ECs adhesion and enhancement of anti-inflammation. Furthermore, In vivo single-cell transcriptome analysis revealed that the proportion of ECs in the cell composition of ECVG surpassed that of PCL, and the tailored endothelialization enabled to convert endothelial cells (ECs) into some specific ECs clusters. One of the specific cluster, Endo_C5 cluster, was only detected in ECVG. Consequently, our study integrates the engineered membrane vesicles of ECVs-N3 from native ECs for tailored endothelialization on SDVG by circumventing the limitations of living cells, and paves a new way to construct the alternative endothelialization in vessel remodeling following injury.

Systemic determinants of brain health in ageing

Preservation of brain health is a worldwide priority. The traditional view is that the major threats to the ageing brain lie within the brain itself. Consequently, therapeutic approaches have focused on protecting the brain from these presumably intrinsic pathogenic processes. However, an increasing body of evidence has unveiled a previously under-recognized contribution of peripheral organs to brain dysfunction and damage. Thus, in addition to the well-known impact of diseases of the heart and endocrine glands on the brain, accumulating data suggest that dysfunction of other organs, such as gut, liver, kidney and lung, substantially affects the development and clinical manifestation of age-related brain pathologies. In this Review, a framework is provided to indicate how organ dysfunction can alter brain homeostasis and promote neurodegeneration, with a focus on dementia. We delineate the associations of subclinical dysfunction in specific organs with dementia risk and provide suggestions for public health promotion and clinical management.

A chitosan-based hydrogel with ultrasound-driven immuno-sonodynamic therapeutic effect for accelerated bacterial infected wound healing

Sonodynamic therapy has attracted much attention as a noninvasive treatment for deep infections. However, it is challenging to achieve high antibacterial activity for hydrogels under ultrasonic irradiation due to the relatively weak sono-catalysis capability of sonosensitizers. Herein, an ultrasound-responsive antibacterial hydrogel (Fe3O4/HA/Ber-LA) composed of Fe3O4-grafted-Berberine, chitosan molecules modified with L-arginine and poly (vinyl alcohol) is prepared for enhanced sonodynamic therapy and immunoregulation. The formation of heterojunction between berberine and Fe3O4 with different work function promotes the charge separation and electron flow and disrupts the conjugated structure of berberine, causing a significant decrease in the band gap, eventually enhancing the sonocatalytic activity. The combination of berberine with Fe3O4 also significantly improves the oxygen adsorption energy, enabling more O2 molecules to react with the electron-rich regions on the surface of Fe3O4 to generate more reactive oxygen species (ROS). L-arginine grafted in the hydrogel is catalyzed by the ROS to release nitric oxide, which not only possesses antibacterial activity, but also positively affects macrophage M1 polarization to display potent phagocytosis to Staphylococcus aureus, thus achieving immuno-sonodynamic therapy. Hence, Fe3O4/HA/Ber-LA hydrogel under ultrasound irradiation shows excellent antibacterial activity. Furthermore, the antioxidative activity and anti-inflammatory effect of berberine released from the hybrid hydrogel induces macrophages to polarize towards the anti-inflammatory M2 status as infection comes under control, thus accelerating the wound healing. The hybrid hydrogel based on the immuno-sonodynamic therapy may be an extraordinary candidate for the treatment of deep infections.

Immunomodulation by endothelial cells: prospects for cancer therapy

Growing evidence highlights the importance of tumor endothelial cells (TECs) in the tumor microenvironment (TME) for promoting tumor growth and evading immune responses. Immunomodulatory endothelial cells (IMECs) represent a distinct plastic phenotype of ECs that exerts the ability to modulate immunity in health and disease. This review discusses our current understanding of IMECs in cancer biology, scrutinizing insights from single-cell reports to compare their characteristics and function dynamics across diverse tumor types, conditions, and species. We investigate possible implications of exploiting IMECs in the context of cancer treatment, particularly examining their influence on the efficacy of existing therapies and the potential to leverage them as targets in optimizing immunotherapeutic strategies.

Single-cell RNA-seq in diabetic foot ulcer wound healing

Diabetic foot ulcer (DFU) is a chronic and serious complication of diabetes mellitus. It is mainly caused by hyperglycaemia, diabetic peripheral vasculopathy and diabetic peripheral neuropathy. These conditions result in ulceration of foot tissues and chronic wounds. If left untreated, DFU can lead to amputation or even endanger the patient's life. Single-cell RNA sequencing (scRNA-seq) is a technique used to identify and characterise transcriptional subpopulations at the single-cell level. It provides insight into cellular function and the molecular drivers of disease. The objective of this paper is to examine the subpopulations, genes and molecules of cells associated with chronic wounds of diabetic foot by using scRNA-seq. The paper aims to explore the wound-healing mechanism of DFU from three aspects: inflammation, angiogenesis and extracellular matrix remodelling. The goal is to gain a better understanding of the mechanism of DFU wound healing and identify possible DFU therapeutic targets, providing new insights for the application of DFU personalised therapy.

CXCL12+ Tumor-associated Endothelial Cells Promote Immune Resistance in Hepatocellular Carcinoma

BACKGROUND

The tumor microenvironment (TME) plays a crucial role in the limited efficacy of existing treatments for hepatocellular carcinoma (HCC), with tumor-associated endothelial cells (TECs) serving as fundamental TME components that substantially influence tumor progression and treatment efficacy. However, the precise roles and mechanisms of TECs in HCC remain inadequately understood.

METHODS

We employed a multi-omics profiling strategy to investigate the single-cell and spatiotemporal evolution of TECs within the microenvironment of HCC tumors showcasing varied responses to immunotherapy. Through an analysis of a clinical cohort of HCC patients, we explored the correlation between TEC subpopulations and immunotherapy outcomes. The influence of TEC subsets on the immune microenvironment was confirmed through comprehensive in vitro and in vivo studies. To further explore the mechanisms of distinct TEC subpopulations in microenvironmental modulation and their impact on immunotherapy, we utilized TEC subset-specific knockout mouse models as well as humanized mouse models.

RESULTS

In this research, we identified a new subset of CXCL12+ TECs that exert a crucial role in immune suppression within the HCC TME. Functionally, CXCL12+ TECs impede the differentiation of CD8+ naïve T cells into CD8+ cytotoxic T cells by secreting CXCL12. Furthermore, they attract myeloid-derived suppressor cells (MDSCs). A bispecific antibody was developed to target both CXCL12 and PD1 specifically, showing significant promise in bolstering anti-tumor immune responses and advancing HCC therapy.

CONCLUSIONS

CXCL12+ TECs are pivotal in mediating immunosuppression within HCC microenvironment and targeting CXCL12+ TECs presents a promising approach to augment the efficacy of immunotherapies in HCC patients.

IMPACT AND IMPLICATION

This investigation reveals a pivotal mechanism in the HCC TME, where CXCL12+ TECs emerge as crucial modulators of immune suppression. The discovery of CXCL12+ TECs as inhibitors of CD8+ naïve T cell activation and recruiters of MDSCs significantly advances our grasp of the dynamic between HCC and immune regulation. Moreover, the development and application of a bispecific antibody precisely targeting CXCL12 and PD1 has proven to enhance immune responses in a humanized mouse HCC model. This finding underscores a promising therapeutic direction for HCC, offering the potential to amplify the impact of current immunotherapies.

Non-Invasive On-Off Fluorescent Biosensor for Endothelial Cell Detection

For rapid and convenient detection of living endothelial cells (ECs) specifically without immunostaining, we developed a biosensor based on turn-on fluorescent protein, named LV-EcpG. It includes a high-affinity peptide E12P obtained through phage display technology for specifically recognizing ECs and a turn-on EGFP fused with two linker peptides. The "on-off" switching mechanism of this genetically encoded fluorescent protein-based biosensor (FPB) ensured that fluorescence signals were activated only when binding with ECs, thus enabling these FPB characters for direct, visual, and non-invasive detection of ECs. Its specificity and multicolor imaging capability established LV-EcpG as a powerful tool for live EC research, with significant potential for diagnosing and treating cardiovascular diseases and tumor angiogenesis.

Targeting the tumour vasculature: from vessel destruction to promotion

As angiogenesis was recognized as a core hallmark of cancer growth and survival, several strategies have been implemented to target the tumour vasculature. Yet to date, attempts have rarely been so diverse, ranging from vessel growth inhibition and destruction to vessel normalization, reprogramming and vessel growth promotion. Some of these strategies, combined with standard of care, have translated into improved cancer therapies, but their successes are constrained to certain cancer types. This Review provides an overview of these vascular targeting approaches and puts them into context based on our subsequent improved understanding of the tumour vasculature as an integral part of the tumour microenvironment with which it is functionally interlinked. This new knowledge has already led to dual targeting of the vascular and immune cell compartments and sets the scene for future investigations of possible alternative approaches that consider the vascular link with other tumour microenvironment components for improved cancer therapy.

Multiscale structure and function of the aortic valve apparatus

Whereas studying the aortic valve in isolation has facilitated the development of life-saving procedures and technologies, the dynamic interplay of the aortic valve and its surrounding structures is vital to preserving their function across the wide range of conditions encountered in an active lifestyle. Our view is that these structures should be viewed as an integrated functional unit, here referred to as the aortic valve apparatus (AVA). The coupling of the aortic valve and root, left ventricular outflow tract, and blood circulation is crucial for AVA's functions: unidirectional flow out of the left ventricle, coronary perfusion, reservoir function, and support of left ventricular function. In this review, we explore the multiscale biological and physical phenomena that underlie the simultaneous fulfillment of these functions. A brief overview of the tools used to investigate the AVA, such as medical imaging modalities, experimental methods, and computational modeling, specifically fluid-structure interaction (FSI) simulations, is included. Some pathologies affecting the AVA are explored, and insights are provided on treatments and interventions that aim to maintain quality of life. The concepts explained in this article support the idea of AVA being an integrated functional unit and help identify unanswered research questions. Incorporating phenomena through the molecular, micro, meso, and whole tissue scales is crucial for understanding the sophisticated normal functions and diseases of the AVA.

Angiogenesis unveiled: Insights into its role and mechanisms in cartilage injury

Osteoarthritis (OA) commonly results in compromised mobility and disability, thereby imposing a significant burden on healthcare systems. Cartilage injury is a prevalent pathological manifestation in OA and constitutes a central focus for the development of treatment strategies. Despite the considerable number of studies aimed at delaying this degenerative process, their outcomes remain unvalidated in preclinical settings. Recently, therapeutic strategies focused on angiogenesis have attracted the growing interest from researchers. Thus, we conducted a comprehensive literature review to elucidate the current progress in research and pinpoint research gaps in this domain. Additionally, it provides theoretical guidance for future research endeavors and the development of treatment strategies.

Endothelial Cell-Derived Extracellular Vesicles Promote Aberrant Neutrophil Trafficking and Subsequent Remote Lung Injury

The development of acute respiratory distress syndrome (ARDS) in sepsis is associated with substantial morbidity and mortality. However, the molecular pathogenesis underlying sepsis-induced ARDS remains elusive. Neutrophil heterogeneity and dysfunction contribute to uncontrolled inflammation in patients with ARDS. A specific subset of neutrophils undergoing reverse transendothelial migration (rTEM), which is characterized by an activated phenotype, is implicated in the systemic dissemination of inflammation. Using single-cell RNA sequencing (scRNA-seq), it identified functionally activated neutrophils exhibiting the rTEM phenotype in the lung of a sepsis mouse model using cecal ligation and puncture. The prevalence of neutrophils with the rTEM phenotype is elevated in the blood of patients with sepsis-associated ARDS and is positively correlated with disease severity. Mechanically, scRNA-seq and proteomic analys revealed that inflamed endothelial cell (EC) released extracellular vesicles (EVs) enriched in karyopherin subunit beta-1 (KPNB1), promoting abluminal-to-luminal neutrophil rTEM. Additionally, EC-derived EVs are elevated and positively correlated with the proportion of rTEM neutrophils in clinical sepsis. Collectively, EC-derived EV is identified as a critical regulator of neutrophil rTEM, providing insights into the contribution of rTEM neutrophils to sepsis-associated lung injury.

The crossroad between tumor and endothelial cells

Endothelial cells are critical in tumor development, and the specific targeting of endothelial cells offers a potent means to effectively impede angiogenesis and suppress the growth of tumors. Tumor endothelial cells are responsible for the loss of anticancer immunity, the so-called endothelial anergy, i.e., the unresponsiveness of tumor endothelial cells to pro-inflammatory stimulation, not allowing adhesion of immune cells to the endothelium. Endothelial cells downregulate antigen presentation and recruitment of immune cells, contributing to immunosuppression. Targeting endothelial cells may assist in improving the immune effect of immune cells in tumor microenvironment.

WISP1 and Macrophage Migration Inhibitory Factor in Respiratory Inflammation: Novel Insights and Therapeutic Potentials for Asthma and COPD

Recent advancements highlight the intricate interplay between the extracellular matrix (ECM) and immune responses, notably in respiratory diseases such as asthma and Chronic Obstructive Pulmonary Disease (COPD). The ECM, a dynamic structural framework within tissues, orches-trates a plethora of cellular processes, including immune cell behavior and tissue repair mecha-nisms. WNT1-inducible-signaling pathway protein 1 (WISP1), a key ECM regulator, controls immune cell behavior, cytokine production, and tissue repair by modulating integrins, PI3K, Akt, β-catenin, and mTOR signaling pathways. WISP1 also induces macrophage migration inhibitory factor (MIF) expression via Src kinases and epidermal growth factor receptor (EGFR) activation. MIF, through its wide range of activities, enhances inflammation and tissue restructuring. Rec-ognized for its versatile roles in regulating the immune system, MIF interacts with multiple immune components, such as the NLRP3 inflammasome, thereby sustaining inflammatory pro-cesses. The WISP1-MIF axis potentially unveils complex molecular mechanisms governing im-mune responses and inflammation. Understanding the intricate roles of WISP1 and MIF in the pathogenesis of chronic respiratory diseases such as asthma and COPD could lead to the identi-fication of novel targets for therapeutic intervention to alleviate disease severity and enhance patient outcomes.

Macrophage-to-osteocyte communication: Impact in a 3D in vitro implant-associated infection model

Macrophages and osteocytes are important regulators of inflammation, osteogenesis and osteoclastogenesis. However, their interactions under adverse conditions, such as biomaterial-associated infection (BAI) are not fully understood. We aimed to elucidate how factors released from macrophages modulate osteocyte responses in an in vitro indirect 3D co-culture model. Human monocyte-derived macrophages were cultured on etched titanium disks and activated with either IL-4 cytokine (anti-inflammatory M2 phenotype) or Staphylococcus aureus secreted virulence factors to simulate BAI (pro-inflammatory M1 phenotype). Primary osteocytes in collagen gels were then stimulated with conditioned media (CM) from these macrophages. The osteocyte response was analyzed by gene expression, protein secretion, and immunostaining. M1 phenotype macrophages were confirmed by IL-1β and TNF-α secretion, and M2 macrophages by ARG-1 and MRC-1.Osteocytes receiving M1 CM revealed bone inhibitory effects, denoted by reduced secretion of bone formation osteocalcin (BGLAP) and increased secretion of the bone inhibitory sclerostin (SOST). These osteocytes also downregulated the pro-mineralization gene PHEX and upregulated the anti-mineralization gene MEPE. Additionally, exhibited pro-osteoclastic potential by upregulating pro-osteoclastic gene RANKL expression. Nonetheless, M1-stimulated osteocytes expressed a higher level of the potent pro-osteogenic factor BMP-2 in parallel with the downregulation of the bone inhibitor genes DKK1 and SOST, suggesting a compensatory feedback mechanisms. Conversely, M2-stimulated osteocytes mainly upregulated anti-osteoclastic gene OPG expression, suggesting an anti-catabolic effect. Altogether, our findings demonstrate a strong communication between M1 macrophages and osteocytes under M1 (BAI)-simulated conditions, suggesting that the BAI adverse effects on osteoblastic and osteoclastic processes in vitro are partly mediated via this communication. STATEMENT OF SIGNIFICANCE: Biomaterial-associated infections are major challenges and the underlying mechanisms in the cellular interactions are missing, especially among the major cells from the inflammatory side (macrophages as the key cell in bacterial clearance) and the regenerative side (osteocyte as main regulator of bone). We evaluated the effect of macrophage polarization driven by the stimulation with bacterial virulence factors on the osteocyte function using an indirect co-culture model, hence mimicking the scenario of a biomaterial-associated infection. The results suggest that at least part of the adverse effects of biomaterial associated infection on osteoblastic and osteoclastic processes in vitro are mediated via macrophage-to-osteocyte communication.

Impact of Methylated Cyclodextrin KLEPTOSE® CRYSMEB on Inflammatory Responses in Human In Vitro Models

KLEPTOSE® CRYSMEB methylated cyclodextrin derivative displays less methylated group substitution than randomly methylated cyclodextrin. It has demonstrated an impact on atherosclerosis and neurological diseases, linked in part to cholesterol complexation and immune response, however, its impact on inflammatory cascade pathways is not clear. Thus, the impact of KLEPTOSE® CRYSMEB on various pharmacological targets was assessed using human umbilical vein endothelial cells under physiological and inflammatory conditions, followed by screening against twelve human primary cell-based systems designed to model complex human tissue and disease biology of the vasculature, skin, lung, and inflammatory tissues using the BioMAP® Diversity PLUS® panel. Finally, its anti-inflammatory mechanism was investigated on peripheral blood mononuclear cells to evaluate anti-inflammatory or pro-resolving properties. The results showed that KLEPTOSE® CRYSMEB can modulate the immune system in vitro and potentially manage vascular issues by stimulating the expression of molecules involved in the crosstalk between immune cells and other cell types. It showed anti-inflammatory effects that were driven by the inhibition of pro-inflammatory cytokine secretion and could have different impacts on different tissue types. Moreover, this cyclodextrin showed no clear impact on pro-resolving lipid mediators. Additionally, it appeared that the mechanism of action of KLEPTOSE® CRYSMEB seems to not be shared by other well-known anti-inflammatory molecules. Finally, KLEPTOSE® CRYSMEB may have an anti-inflammatory impact, which could be due to its effect on receptors such as TLR or direct complexation with LPS or PGE2, and conversely, this methylated cyclodextrin could stimulate a pro-inflammatory response involving lipid mediators and on proteins involved in communication with immune cells, probably via interaction with membrane cholesterol.

Vascularized platforms for investigating cell communication via extracellular vesicles

The vascular network plays an essential role in the maintenance of all organs in the body via the regulated delivery of oxygen and nutrients, as well as tissue communication via the transfer of various biological signaling molecules. It also serves as a route for drug administration and affects pharmacokinetics. Due to this importance, engineers have sought to create physiologically relevant and reproducible vascular systems in tissue, considering cell-cell and extracellular matrix interaction with structural and physical conditions in the microenvironment. Extracellular vesicles (EVs) have recently emerged as important carriers for transferring proteins and genetic material between cells and organs, as well as for drug delivery. Vascularized platforms can be an ideal system for studying interactions between blood vessels and EVs, which are crucial for understanding EV-mediated substance transfer in various biological situations. This review summarizes recent advances in vascularized platforms, standard and microfluidic-based techniques for EV isolation and characterization, and studies of EVs in vascularized platforms. It provides insights into EV-related (patho)physiological regulations and facilitates the development of EV-based therapeutics.

Pan-cancer integrative analyses dissect the remodeling of endothelial cells in human cancers

Therapeutics targeting tumor endothelial cells (TECs) have been explored for decades, with only suboptimal efficacy achieved, partly due to an insufficient understanding of the TEC heterogeneity across cancer patients. We integrated single-cell RNA-seq data of 575 cancer patients from 19 solid tumor types, comprehensively charting the TEC phenotypic diversities. Our analyses uncovered underappreciated compositional and functional heterogeneity in TECs from a pan-cancer perspective. Two subsets, CXCR4 + tip cells and SELE + veins, represented the prominent angiogenic and proinflammatory phenotypes of TECs, respectively. They exhibited distinct spatial organization patterns, and compared to adjacent non-tumor tissues, tumor tissue showed an increased prevalence of CXCR4 + tip cells, yet with SELE + veins depleted. Such functional and spatial characteristics underlie their differential associations with the response of anti-angiogenic therapies and immunotherapies. Our integrative resources and findings open new avenues to understand and clinically intervene in the tumor vasculature.

Lung Fibrosis Is Linked to Increased Endothelial Cell Activation and Dysfunctional Vascular Barrier Integrity

Pulmonary fibrosis (PF) can be a fatal disease characterized by progressive lung scarring. It is still poorly understood how the pulmonary endothelium is involved in the disease pathogenesis. Differences of the pulmonary vasculature between patients and donors were analyzed using transmission electron microscopy, immunohistochemistry, and single-cell RNA sequencing. Vascular barrier resistance, endothelial-immune cell adhesion, and sensitivity to an inflammatory milieu were studied in vitro. Integrity and activation markers were measured by ELISA in human plasma. Transmission electron microscopy demonstrated abnormally swollen endothelial cells (ECs) in fibrotic lungs compared with donors. A more intense CD31 and von Willebrand Factor (vWF) and patchy vascular endothelial (VE)-Cadherin staining in fibrotic lungs supported the presence of a dysregulated endothelium. Integrity markers CD31, VE-Cadherin, Thrombomodulin, and VEGFR-2 (vascular endothelial growth factor receptor-2) and activation marker vWF gene expression was increased in different endothelial subpopulations (e.g., arterial, venous, general capillary, aerocytes) in PF. This was associated with a heightened sensitivity of fibrotic ECs to TNF-α or IFN-γ and elevated immune cell adhesion. The barrier strength was overall reduced in ECs from fibrotic lungs. vWF and IL-8 were increased in the plasma of patients, whereas VE-Cadherin, Thrombomodulin, and VEGFR-2 were decreased. VE-Cadherin staining was also patchy in biopsy tissue and was decreased in plasma samples of patients with PF 6 months after the initial diagnosis. Our data demonstrate highly abnormal ECs in PF. The vascular compartment is characterized by hyperactivation and increased immune cell adhesion, as well as dysfunctional endothelial barrier function. Reestablishing EC homeostasis and function might represent a new therapeutic option for fibrotic lung diseases.

Endothelial cell heterogeneity in colorectal cancer: tip cells drive angiogenesis

This study aims to uncover the heterogeneity of endothelial cells (ECs) in colorectal cancer (CRC) and their crucial role in angiogenesis, with a special focus on tip cells. Using single-cell RNA sequencing to profile ECs, our data suggests that CRC ECs predominantly exhibit enhanced angiogenesis and decreased antigen presentation, a shift in phenotype largely steered by tip cells. We also observed that an increase in the density and proportion of tip cells correlates with CRC occurrence, progression, and poorer patient prognosis. Furthermore, we identified endothelial cell-specific molecule 1 (ESM1), specifically expressed in tip cells, sustains a VEGFA-KDR-ESM1 positive feedback loop, promoting angiogenesis and CRC proliferation and migration. We also found the enrichment of KDR in tip cells and spotlight a unique long-tail effect in VEGFA expression: while VEGFA is primarily expressed by epithelial cells, the highest level of VEGFA expression is found in individual myeloid cells. Moreover, we observed that effective PD-1 blockade immunotherapy significantly reduced tip cells, disrupting the VEGFA-KDR-ESM1 positive feedback loop in the process. Our investigation into the heterogeneity of ECs in CRC at a single-cell level offers important insights that may contribute to the development of more effective immunotherapies targeting tip cells in CRC.

Mononuclear Phagocytes, Cellular Immunity, and Nobel Prizes: A Historic Perspective

The mononuclear phagocyte system includes monocytes, macrophages, some dendritic cells, and multinuclear giant cells. These cell populations display marked heterogeneity depending on their differentiation from embryonic and bone marrow hematopoietic progenitors, tissue location, and activation. They contribute to tissue homeostasis by interacting with local and systemic immune and non-immune cells through trophic, clearance, and cytocidal functions. During evolution, they contributed to the innate host defense before effector mechanisms of specific adaptive immunity emerged. Mouse macrophages appear at mid-gestation and are distributed throughout the embryo to facilitate organogenesis and clear cells undergoing programmed cell death. Yolk sac, AGM, and fetal liver-derived tissue-resident macrophages persist throughout postnatal and adult life, supplemented by bone marrow-derived blood monocytes, as required after injury and infection. Nobel awards to Elie Metchnikoff and Paul Ehrlich in 1908 drew attention to cellular phagocytic and humoral immunity, respectively. In 2011, prizes were awarded to Jules Hoffmann and Bruce Beutler for contributions to innate immunity and to Ralph Steinman for the discovery of dendritic cells and their role in antigen presentation to T lymphocytes. We trace milestones in the history of mononuclear phagocyte research from the perspective of Nobel awards bearing directly and indirectly on their role in cellular immunity.

Analysis of intracellular communication reveals consistent gene changes associated with early-stage acne skin

A comprehensive understanding of the intricate cellular and molecular changes governing the complex interactions between cells within acne lesions is currently lacking. Herein, we analyzed early papules from six subjects with active acne vulgaris, utilizing single-cell and high-resolution spatial RNA sequencing. We observed significant changes in signaling pathways across seven different cell types when comparing lesional skin samples (LSS) to healthy skin samples (HSS). Using CellChat, we constructed an atlas of signaling pathways for the HSS, identifying key signal distributions and cell-specific genes within individual clusters. Further, our comparative analysis revealed changes in 49 signaling pathways across all cell clusters in the LSS- 4 exhibited decreased activity, whereas 45 were upregulated, suggesting that acne significantly alters cellular dynamics. We identified ten molecules, including GRN, IL-13RA1 and SDC1 that were consistently altered in all donors. Subsequently, we focused on the function of GRN and IL-13RA1 in TREM2 macrophages and keratinocytes as these cells participate in inflammation and hyperkeratinization in the early stages of acne development. We evaluated their function in TREM2 macrophages and the HaCaT cell line. We found that GRN increased the expression of proinflammatory cytokines and chemokines, including IL-18, CCL5, and CXCL2 in TREM2 macrophages. Additionally, the activation of IL-13RA1 by IL-13 in HaCaT cells promoted the dysregulation of genes associated with hyperkeratinization, including KRT17, KRT16, and FLG. These findings suggest that modulating the GRN-SORT1 and IL-13-IL-13RA1 signaling pathways could be a promising approach for developing new acne treatments.

Maternal n-3 enriched diet reprograms the offspring neurovascular transcriptome and blunts inflammation induced by endotoxin in the neonate

Infection during the perinatal period can adversely affect brain development, predispose infants to ischemic stroke and have lifelong consequences. We previously demonstrated that diet enriched in n-3 polyunsaturated fatty acids (n-3 PUFA) transforms brain lipid composition in the offspring and protects the neonatal brain from stroke, in part by blunting injurious immune responses. Critical to the interface between the brain and systemic circulation is the vasculature, endothelial cells in particular, that support brain homeostasis and provide a barrier to systemic infection. Here, we examined whether maternal PUFA-enriched diets exert reprograming of endothelial cell signalling in postnatal day 9 mice after modeling aspects of infection using LPS. Transcriptome analysis was performed on microvessels isolated from brains of pups from dams maintained on 3 different maternal diets from gestation day 1: standard, n-3 enriched or n-6 enriched diets. Depending on the diet, in endothelial cells LPS produced distinct regulation of pathways related to immune response, cell cycle, extracellular matrix, and angiogenesis. N-3 PUFA diet enabled higher immune reactivity in brain vasculature, while preventing imbalance of cell cycle regulation and extracellular matrix cascades that accompanied inflammatory response in standard diet. Cytokine analysis revealed a blunted LPS response in blood and brain of offspring from dams on n-3 enriched diet. Analysis of cerebral vasculature in offspring in vivo revealed no differences in vessel density. However, vessel complexity was decreased in response to LPS at 72 h in standard and n-6 diets. Thus, LPS modulates specific transcriptomic changes in brain vessels of offspring rather than major structural vessel characteristics during early life. N-3 PUFA-enriched maternal diet in part prevents an imbalance in homeostatic processes, alters inflammation and ultimately mitigates changes to the complexity of surface vessel networks that result from infection. Importantly, maternal diet may presage offspring neurovascular outcomes later in life.

Magnesium lithospermate B enhances the potential of human-induced pluripotent stem cell-derived cardiomyocytes for myocardial repair

BACKGROUND

We previously reported that activation of the cell cycle in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) enhances their remuscularization capacity after human cardiac muscle patch transplantation in infarcted mouse hearts. Herein, we sought to identify the effect of magnesium lithospermate B (MLB) on hiPSC-CMs during myocardial repair using a myocardial infarction (MI) mouse model.

METHODS

In C57BL/6 mice, MI was surgically induced by ligating the left anterior descending coronary artery. The mice were randomly divided into five groups ( n = 10 per group); a MI group (treated with phosphate-buffered saline only), a hiPSC-CMs group, a MLB group, a hiPSC-CMs + MLB group, and a Sham operation group. Cardiac function and MLB therapeutic efficacy were evaluated by echocardiography and histochemical staining 4 weeks after surgery. To identify the associated mechanism, nuclear factor (NF)-κB p65 and intercellular cell adhesion molecule-1 (ICAM1) signals, cell adhesion ability, generation of reactive oxygen species, and rates of apoptosis were detected in human umbilical vein endothelial cells (HUVECs) and hiPSC-CMs.

RESULTS

After 4 weeks of transplantation, the number of cells that engrafted in the hiPSC-CMs + MLB group was about five times higher than those in the hiPSC-CMs group. Additionally, MLB treatment significantly reduced tohoku hospital pediatrics-1 (THP-1) cell adhesion, ICAM1 expression, NF-κB nuclear translocation, reactive oxygen species production, NF-κB p65 phosphorylation, and cell apoptosis in HUVECs cultured under hypoxia. Similarly, treatment with MLB significantly inhibited the apoptosis of hiPSC-CMs via enhancing signal transducer and activator of transcription 3 (STAT3) phosphorylation and B-cell lymphoma-2 (BCL2) expression, promoting STAT3 nuclear translocation, and downregulating BCL2-Associated X, dual specificity phosphatase 2 (DUSP2), and cleaved-caspase-3 expression under hypoxia. Furthermore, MLB significantly suppressed the production of malondialdehyde and lactate dehydrogenase and the reduction in glutathione content induced by hypoxia in both HUVECs and hiPSC-CMs in vitro .

CONCLUSIONS

MLB significantly enhanced the potential of hiPSC-CMs in repairing injured myocardium by improving endothelial cell function via the NF-κB/ICAM1 pathway and inhibiting hiPSC-CMs apoptosis via the DUSP2/STAT3 pathway.

Inflammatory breast cancer microenvironment repertoire based on DNA methylation data deconvolution reveals actionable targets to enhance the treatment efficacy

BACKGROUND

Although the clinical signs of inflammatory breast cancer (IBC) resemble acute inflammation, the role played by infiltrating immune and stromal cells in this aggressive disease is uncharted. The tumor microenvironment (TME) presents molecular alterations, such as epimutations, prior to morphological abnormalities. These changes affect the distribution and the intricate communication between the TME components related to cancer prognosis and therapy response. Herein, we explored the global DNA methylation profile of IBC and surrounding tissues to estimate the microenvironment cellular composition and identify epigenetically dysregulated markers.

METHODS

We used the HiTIMED algorithm to deconvolve the bulk DNA methylation data of 24 IBC and six surrounding non-tumoral tissues (SNT) (GSE238092) and determine their cellular composition. The prognostic relevance of cell types infiltrating IBC and their relationship with clinicopathological variables were investigated. CD34 (endothelial cell marker) and CD68 (macrophage marker) immunofluorescence staining was evaluated in an independent set of 17 IBC and 16 non-IBC samples.

RESULTS

We found lower infiltration of endothelial, stromal, memory B, dendritic, and natural killer cells in IBC than in SNT samples. Higher endothelial cell (EC) and stromal cell content were related to better overall survival. EC proportions positively correlated with memory B and memory CD8+ T infiltration in IBC. Immune and EC markers exhibited distinct DNA methylation profiles between IBC and SNT samples, revealing hypermethylated regions mapped to six genes (CD40, CD34, EMCN, HLA-G, PDPN, and TEK). We identified significantly higher CD34 and CD68 protein expression in IBC compared to non-IBC.

CONCLUSIONS

Our findings underscored cell subsets that distinguished patients with better survival and dysregulated markers potentially actionable through combinations of immunotherapy and epigenetic drugs.