Extracellular histones reduce survival and angiogenic responses of late outgrowth progenitor and mature endothelial cells

Endothelial Colony-Forming Cells (ECFCs) in cerebrovascular aging: Focus on the pathogenesis of Vascular Cognitive Impairment and Dementia (VCID), and treatment prospects

Endothelial colony-forming cells (ECFCs), a unique endothelial progenitor subset, are essential for vascular integrity and repair, providing significant regenerative potential. Recent studies highlight their role in cerebrovascular aging, particularly in the pathogenesis of vascular cognitive impairment and dementia (VCID). Aging disrupts ECFC functionality through mechanisms such as oxidative stress, chronic inflammation, and cellular senescence, leading to compromised vascular repair and reduced neurovascular resilience. ECFCs influence key cerebrovascular processes, including neurovascular coupling (NVC), blood-brain barrier (BBB) integrity, and vascular regeneration, which are critical for cognitive health. Age-related decline in ECFC quantity and functionality contributes to vascular rarefaction, diminished cerebral blood flow (CBF), and BBB permeability-processes that collectively exacerbate cognitive decline. This review delves into the multifaceted role of ECFCs in cerebrovascular aging and underscores their potential as therapeutic targets in addressing age-related vascular dysfunctions, presenting new directions for mitigating the effects of aging on brain health.

M6229 Protects against Extracellular-Histone-Induced Liver Injury, Kidney Dysfunction, and Mortality in a Rat Model of Acute Hyperinflammation

Extracellular histones have been shown to act as DAMPs in a variety of inflammatory diseases. Moreover, they have the ability to induce cell death. In this study, we show that M6229, a low-anticoagulant fraction of unfractionated heparin (UFH), rescues rats that were challenged by continuous infusion of calf thymus histones at a rate of 25 mg histones/kg/h. Histone infusion by itself induced hepatic and homeostatic dysfunction characterized by elevated activity of hepatic enzymes (ASAT and ALAT) and serum lactate levels as well as by a renal dysfunction, which contributed to the significantly increased mortality rate. M6229 was able to restore normal levels of both hepatic and renal parameters at 3 and 9 mg M6229/kg/h and prevented mortality of the animals. We conclude that M6229 is a promising therapeutic agent to treat histone-mediated disease.

Proteomic Analysis on Sequential Samples of Cystic Fluid Obtained from Human Brain Tumors

Cystic formation in human primary brain tumors is a relatively rare event whose incidence varies widely according to the histotype of the tumor. Composition of the cystic fluid has mostly been characterized in samples collected at the time of tumor resection and no indications of the evolution of cystic content are available. We characterized the evolution of the proteome of cystic fluid using a bottom-up proteomic approach on sequential samples obtained from secretory meningioma (SM), cystic schwannoma (CS) and cystic high-grade glioma (CG). We identified 1008 different proteins; 74 of these proteins were found at least once in the cystic fluid of all tumors. The most abundant proteins common to all tumors studied derived from plasma, with the exception of prostaglandin D2 synthase, which is a marker of cerebrospinal fluid origin. Overall, the protein composition of cystic fluid obtained at different times from the same tumor remained stable. After the identification of differentially expressed proteins (DEPs) and the protein-protein interaction network analysis, we identified the presence of tumor-specific pathways that may help to characterize tumor-host interactions. Our results suggest that plasma proteins leaking from local blood-brain barrier disruption are important contributors to cyst fluid formation, but cerebrospinal fluid (CSF) and the tumor itself also contribute to the cystic fluid proteome and, in some cases, as with immunoglobulin G, shows tumor-specific variations that cannot be simply explained by differences in vessel permeability or blood contamination.

Validation of circulating histone detection by mass spectrometry for early diagnosis, prognosis, and management of critically ill septic patients

BACKGROUND

As leading contributors to worldwide morbidity and mortality, sepsis and septic shock are considered a major global health concern. Proactive biomarker identification in patients with sepsis suspicion at any time remains a daunting challenge for hospitals. Despite great progress in the understanding of clinical and molecular aspects of sepsis, its definition, diagnosis, and treatment remain challenging, highlighting a need for new biomarkers with potential to improve critically ill patient management. In this study we validate a quantitative mass spectrometry method to measure circulating histone levels in plasma samples for the diagnosis and prognosis of sepsis and septic shock patients.

METHODS

We used the mass spectrometry technique of multiple reaction monitoring to quantify circulating histones H2B and H3 in plasma from a monocenter cohort of critically ill patients admitted to an Intensive Care Unit (ICU) and evaluated its performance for the diagnosis and prognosis of sepsis and septic shock (SS).

RESULTS

Our results highlight the potential of our test for early diagnosis of sepsis and SS. H2B levels above 121.40 ng/mL (IQR 446.70) were indicative of SS. The value of blood circulating histones to identify a subset of SS patients in a more severe stage with associated organ failure was also tested, revealing circulating levels of histones H2B above 435.61 ng/ml (IQR 2407.10) and H3 above 300.61 ng/ml (IQR 912.77) in septic shock patients with organ failure requiring invasive organ support therapies. Importantly, we found levels of H2B and H3 above 400.44 ng/mL (IQR 1335.54) and 258.25 (IQR 470.44), respectively in those patients who debut with disseminated intravascular coagulation (DIC). Finally, a receiver operating characteristic curve (ROC curve) demonstrated the prognostic value of circulating histone H3 to predict fatal outcomes and found for histone H3 an area under the curve (AUC) of 0.720 (CI 0.546-0.895) p < 0.016 on a positive test cut-off point at 486.84 ng/mL, showing a sensitivity of 66.7% and specificity of 73.9%.

CONCLUSIONS

Circulating histones analyzed by MS can be used to diagnose SS and identify patients at high risk of suffering DIC and fatal outcome.

Extracellular histone release by renal cells after warm and cold ischemic kidney injury: Studies in an ex-vivo porcine kidney perfusion model

Extracellular histones are cytotoxic molecules involved in experimental acute kidney injury. In patients receiving a renal transplant from donors after circulatory death, who suffer from additional warm ischemia, worse graft outcome is associated with higher machine perfusate extracellular histone H3 concentrations. We now investigated temperature-dependent extracellular histone release in an ex vivo porcine renal perfusion model, and subsequently studied histone release in the absence and presence of non-anticoagulant heparin. Seven pairs of ischemically damaged porcine kidneys were machine perfused at 4°C (cold ischemia) or 28°C (warm ischemia). Perfusate histone H3 concentration was higher after warm as compared to cold ischemia (median (IQR) = 0.48 (0.20-0.83) μg/mL vs. 0.02 (0.00-0.06) μg/mL; p = .045, respectively). Employing immune-electron microscopy (EM), histone containing cytoplasmic protrusions of tubular and endothelial cells were found after warm ischemic injury. Furthermore, abundant histone localization was detected in debris surrounding severely damaged glomerular cells, in a "buck shot" pattern. In vitro, histones were cytotoxic to endothelial and kidney epithelial cells in a temperature-dependent manner. In a separate ex vivo experiment, addition of heparin did not change the total histone H3 levels observed in the perfusate but revealed a continuous increase in the level of a lower molecular weight histone H3 variant. Our findings show that ischemically damaged kidneys release more extracellular histones in warm ischemia, which by EM was due to histone release by renal cells. Blocking of histone-mediated damage during transplantation may be beneficial in prevention of renal injury.

The Double-Edged Proteins in Cancer Proteomes and the Generation of Induced Tumor-Suppressing Cells (iTSCs)

Unlike a prevalent expectation that tumor cells secrete tumor-promoting proteins and stimulate the progression of neighboring tumor cells, accumulating evidence indicates that the role of tumor-secreted proteins is double-edged and context-dependent. Some of the oncogenic proteins in the cytoplasm and cell membranes, which are considered to promote the proliferation and migration of tumor cells, may inversely act as tumor-suppressing proteins in the extracellular domain. Furthermore, the action of tumor-secreted proteins by aggressive "super-fit" tumor cells can be different from those derived from "less-fit" tumor cells. Tumor cells that are exposed to chemotherapeutic agents could alter their secretory proteomes. Super-fit tumor cells tend to secrete tumor-suppressing proteins, while less-fit or chemotherapeutic agent-treated tumor cells may secrete tumor-promotive proteomes. Interestingly, proteomes derived from nontumor cells such as mesenchymal stem cells and peripheral blood mononuclear cells mostly share common features with tumor cell-derived proteomes in response to certain signals. This review introduces the double-sided functions of tumor-secreted proteins and describes the proposed underlying mechanism, which would possibly be based on cell competition.

Histone Citrullination Mediates a Protective Role in Endothelium and Modulates Inflammation

NETosis is a key host immune process against a pathogenic infection during innate immune activation, consisting of a neutrophil "explosion" and, consequently, NET formation, containing mainly DNA, histones, and other nuclear proteins. During sepsis, an exacerbated immune host response to an infection occurs, activating the innate immunity and NETosis events, which requires histone H3 citrullination. Our group compared the circulating histone levels with those citrullinated H3 levels in plasma samples of septic patients. In addition, we demonstrated that citrullinated histones were less cytotoxic for endothelial cells than histones without this post-translational modification. Citrullinated histones did not affect cell viability and did not activate oxidative stress. Nevertheless, citrullinated histones induced an inflammatory response, as well as regulatory endothelial mechanisms. Furthermore, septic patients showed elevated levels of circulating citrullinated histone H3, indicating that the histone citrullination is produced during the first stages of sepsis, probably due to the NETosis process.

The Contribution of Neutrophils and NETs to the Development of Type 1 Diabetes

Type 1 diabetes (T1D) is an autoimmune disease resulting from the destruction of insulin-producing beta cells in pancreatic islets. T lymphocytes are the claimed pathogenic effectors but abnormalities of other immune cell types, including neutrophils, also characterize T1D development. During human T1D natural history, neutrophils are reduced in the circulation, while accumulate in the pancreas where release of neutrophil extracellular traps (NETs), or NETosis, is manifest. Recent-onset T1D patients also demonstrate activated circulating neutrophils, associated with a unique neutrophil gene signature. Neutrophils can bind to platelets, leading to the formation of platelet-neutrophil aggregates (PNAs). PNAs increase in the circulation during the development of human T1D and provide a mechanism for neutrophil activation and mobilization/recruitment to the pancreas. In non-obese diabetic or NOD mice, T1D autoimmunity is accompanied by dynamic changes in neutrophil numbers, activation state, PNAs and/or NETosis/NET proteins in the circulation, pancreas and/or islets. Such properties differ between stages of T1D disease and underpin potentially indirect and direct impacts of the innate immune system in T1D pathogenesis. Supporting the potential for a pathogenic role in T1D, NETs and extracellular histones can directly damage isolated islets in vitro, a toxicity that can be prevented by small polyanions. In human T1D, NET-related damage can target the whole pancreas, including both the endocrine and exocrine components, and contribute to beta cell destruction, providing evidence for a neutrophil-associated T1D endotype. Future intervention in T1D could therefore benefit from combined strategies targeting T cells and accessory destructive elements of activated neutrophils.

Histone 2B Facilitates Plasminogen-Enhanced Endothelial Migration through Protease-Activated Receptor 1 (PAR1) and Protease-Activated Receptor 2 (PAR2)

Plasminogen and its multiple receptors have been implicated in the responses of many different cell types. Among these receptors, histone 2B (H2B) has been shown to play a prominent role in macrophage responses. The contribution of H2B to plasminogen-induced endothelial migration, an event relevant to wound healing and angiogenesis, is unknown. Plasminogen enhanced the migration of endothelial cells, which was inhibited by both Protease-Activated Receptor-1 (PAR1) and 2 (PAR2) antagonists. H2B was detected on viable endothelial cells of venous and arterial origin, and an antibody to H2B that blocks plasminogen binding also inhibited the plasminogen-dependent migration by these cells. The antibody blockade was as effective as PAR1 or PAR2 antagonists in inhibiting endothelial cell migration. In pull-down experiments, H2B formed a complex with both PAR1 and PAR2 but not β3 integrin, another receptor implicated in endothelial migration in the presence of plasminogen. H2B was found to be associated with clathrin adapator protein, AP2µ (clathrin AP2µ) and β-arrestin2, which are central to the internationalization/signaling machinery of the PARs. These associations with PAR1-clathrin adaptor AP2µ- and PAR2-β-arrestin2-dependent internalization/signaling pathways provide a mechanism to link plasminogen to responses such as wound healing and angiogenesis.

Circulating platelet-neutrophil aggregates characterize the development of type 1 diabetes in humans and NOD mice

Platelet-neutrophil aggregates (PNAs) facilitate neutrophil activation and migration and could underpin the recruitment of neutrophils to the pancreas during type 1 diabetes (T1D) pathogenesis. PNAs, measured by flow cytometry, were significantly elevated in the circulation of autoantibody-positive (Aab⁺) children and new-onset T1D children, as well as in pre-T1D (at 4 weeks and 10–12 weeks) and T1D-onset NOD mice, compared with relevant controls, and PNAs were characterized by activated P-selectin⁺ platelets. PNAs were similarly increased in pre-T1D and T1D-onset NOD isolated islets/insulitis, and immunofluorescence staining revealed increased islet-associated neutrophil extracellular trap (NET) products (myeloperoxidase [MPO] and citrullinated histones [CitH3]) in NOD pancreata. In vitro, cell-free histones and NETs induced islet cell damage, which was prevented by the small polyanionic drug methyl cellobiose sulfate (mCBS) that binds to histones and neutralizes their pathological effects. Elevated circulating PNAs could, therefore, act as an innate immune and pathogenic biomarker of T1D autoimmunity. Platelet hyperreactivity within PNAs appears to represent a previously unrecognized hematological abnormality that precedes T1D onset. In summary, PNAs could contribute to the pathogenesis of T1D and potentially function as a pre-T1D diagnostic.

Bioglass promotes wound healing by inhibiting endothelial cell pyroptosis through regulation of the connexin 43/reactive oxygen species (ROS) signaling pathway

Bioactive glass (BG) has recently shown great promise in soft tissue repair, especially in wound healing; however, the underlying mechanism remains unclear. Pyroptosis is a novel type of programmed cell death that is involved in various traumatic injury diseases. Here, we hypothesized that BG may promote wound healing through suppression of pyroptosis. To test this scenario, we investigated the possible effect of BG on pyroptosis in wound healing both in vivo and in vitro. This study showed that BG can accelerate wound closure, granulation formation, collagen deposition, and angiogenesis. Moreover, western blot analysis and immunofluorescence staining revealed that BG inhibited the expression of pyroptosis-related proteins in vivo and in vitro. In addition, while BG regulated the expression of connexin43 (Cx43), it inhibited reactive oxygen species (ROS) production. Cx43 activation and inhibition experiments further indicate that BG inhibited pyroptosis in endothelial cells by decreasing Cx43 expression and ROS levels. Taken together, these studies suggest that BG promotes wound healing by inhibiting pyroptosis via Cx43/ROS signaling pathway.

Expression of a Crry/p65 is reduced in acute lung injury induced by extracellular histones

Acute lung injury (ALI) occurs in patients with severe sepsis and has a mortality rate of 40%–60%. Severe sepsis promotes the release of histones from dying cells, which can induce platelet aggregation, activate coagulation and cause endothelial cell (EC) death. We previously reported that the expression of membrane complement receptor type 1‐related gene Y (Crry)/p65, which plays a principal role in defence against abnormal activation of complement in the blood, is reduced in response to peritoneal mesothelial cell injury, and we hence hypothesized that a similar mechanism occurs in pulmonary ECs. In this study, we examined the role of Crry/p65 in histone‐mediated ALI using an experimental animal model. In ALI model mice, exposure to extracellular histones induces lung injury and results in a decrease in Crry/p65 expression. The levels of lactic acid dehydrogenase (LDH), a marker of cell damage, were significantly increased in the serum of ALI model compared with vehicle mice. The significant inverse correlation between the expression of Crry/p65 and LDH levels in plasma revealed an association between Crry/p65 expression and cell damage. The levels of complement component 3a (C3a) were also significantly increased in the serum of the ALI model compared with vehicle mice. Notably, a C3a receptor antagonist ameliorated lung injury induced by histones. We hypothesize that extracellular histones induce complement activation via down‐regulation of Crry/p65 and that C3a might serve as a therapeutic target for the treatment of ALI.

Acute cadmium exposure induces GSDME-mediated pyroptosis in triple-negative breast cancer cells through ROS generation and NLRP3 inflammasome pathway activation

Cadmium (Cd) exposure can exert an impact on carcinogenicity of breast cancer, however, the mechanism is not fully understood in triple-negative breast cancer (TNBC). We performed a TNBC MDA-MB-231 cell model and assessed the toxic effect of Cd exposure (0, 10, 20, 50, 60, 80 μM). Cd reduced cell viability in a time- and dose-dependent manner, followed by cell cycle arrest in S phase with alterations of cyclin 1A1, cyclin 1D1 and CDK2. Lactate dehydrogenase (LDH) release, apoptosis and pyroptosis were increased, which were relieved by z-VAD. Elevated ROS and NLRP3, caspase-1, IL-1β and IL-18 were detected, which was attenuated by N-acetylcysteine. Increased bax and decreased caspase-8, caspase-9 and caspase-3 were found. gasdermin E (GSDME) was activated with cleavage of GSDME-NT, which was retarded by z-VAD. Additionally, p38 MAPK signaling pathway was activated. Our data demonstrate GSDME-activated pyroptosis in Cd toxicity, implying a potential impact on TNBC.

Comparative Analysis of Chromatin-Delivered Biomarkers in the Monitoring of Sepsis and Septic Shock: A Pilot Study

Sepsis management remains one of the most important challenges in modern clinical practice. Rapid progression from sepsis to septic shock is practically unpredictable, hence the critical need for sepsis biomarkers that can help clinicians in the management of patients to reduce the probability of a fatal outcome. Circulating nucleoproteins released during the inflammatory response to infection, including neutrophil extracellular traps, nucleosomes, and histones, and nuclear proteins like HMGB1, have been proposed as markers of disease progression since they are related to inflammation, oxidative stress, endothelial damage, and impairment of the coagulation response, among other pathological features. The aim of this work was to evaluate the actual potential for decision making/outcome prediction of the most commonly proposed chromatin-related biomarkers (i.e., nucleosomes, citrullinated H3, and HMGB1). To do this, we compared different ELISA measuring methods for quantifying plasma nucleoproteins in a cohort of critically ill patients diagnosed with sepsis or septic shock compared to nonseptic patients admitted to the intensive care unit (ICU), as well as to healthy subjects. Our results show that all studied biomarkers can be used to monitor sepsis progression, although they vary in their effectiveness to separate sepsis and septic shock patients. Our data suggest that HMGB1/citrullinated H3 determination in plasma is potentially the most promising clinical tool for the monitoring and stratification of septic patients.

Pyroptosis: A New Regulating Mechanism in Cardiovascular Disease

Pyroptosis is a kind of pro-inflammatory cell death. Compared with autophagy and apoptosis, pyroptosis has unique characteristics in morphology and mechanism. Specifically, pyroptosis is a kind of cell lysis mediated by the Gasdermin family, releases inflammatory cytokines IL-1β and IL-18. There are three different forms of mechanism, which are caspase-1-mediated, caspase-4/5/11-mediated and caspase-3-mediated. A large number of studies have proved that pyroptosis is closely related to cardiovascular disease. This paper reviewed the recent progress in the related research on pyroptosis and myocardial infarction, ischemia-reperfusion, atherosclerosis, diabetic cardiomyopathy, arrhythmia, heart failure hypertension and Kawasaki disease. Therefore, we believe that pyroptosis may be a new therapeutic target in the cardiovascular field.

Reactions Related to CAR-T Cell Therapy

The application of chimeric antigen receptor (CAR) T-cell therapy as a tumor immunotherapy has received great interest in recent years. This therapeutic approach has been used to treat hematological malignancies solid tumors. However, it is associated with adverse reactions such as, cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), off-target effects, anaphylaxis, infections associated with CAR-T-cell infusion (CTI), tumor lysis syndrome (TLS), B-cell dysplasia, hemophagocytic lymphohistiocytosis (HLH)/macrophage activation syndrome (MAS) and coagulation disorders. These adverse reactions can be life-threatening, and thus they should be identified early and treated effectively. In this paper, we review the adverse reactions associated with CAR-T cells, the mechanisms driving such adverse reactions, and strategies to subvert them. This review will provide important reference data to guide clinical application of CAR-T cell therapy.

Platelets and extracellular traps in infections

Platelets have a well-recognized role in hemostasis and thrombosis, and they are important amplifiers of inflammation and innate immune responses. The formation of DNA extracellular traps (ETs) is a complex cellular mechanism, which occurs in response to microbial infections and sterile inflammation, and results in the release of DNA complexed with histones and various granular proteins. ETs were first discovered in neutrophils (NETs); however, it is now accepted that other leukocytes, including eosinophils (EETs) and monocytes/macrophages (MoETs/METs), can also generate them. Moreover, several types of ETs have been described.Increasing evidence has demonstrated that platelets modulate the formation of ETs. This review summarizes recent findings about the physiopathological role of platelets in the formation of ETs during infection and future perspectives in the field.

Inhibition of the Growth of Breast Cancer-Associated Brain Tumors by the Osteocyte-Derived Conditioned Medium

The brain is a common site of metastasis from advanced breast cancer but few effective treatments are available. We examined a therapeutic option with a conditioned medium (CM), focusing on the role of Lrp5 and β-catenin in Wnt signaling, and IL1ra in osteocytes. Osteocytes presented the innate anti-tumor effect and the overexpression of the above genes strengthened their action. In a mouse model, the injection of their CM inhibited mammary tumors and tumor-driven osteolysis. Importantly, Lrp5- and/or IL1ra-overexpressing osteocytes or the local administration of β-catenin-overexpressing CM markedly inhibited brain tumors. In the transport analysis, tumor-suppressing factors in CM were shown to diffuse through the skull. Mechanistically, the CM with overexpression of the above genes downregulated oncogenic genes such as MMP9, Runx2, TGFβ, and Snail in breast cancer cells. Also, the CM with β-catenin overexpression downregulated CXCL1 and CXCL5 and upregulated tumor suppressors such as LIMA1, DSP, p53, and TRAIL in breast cancer cells. Notably, whole-genome proteomics revealed that histone H4 was enriched in CM and acted as an atypical tumor suppressor. Lrp5-overexpressing MSCs were also shown to act as anti-tumor agents. Collectively, this study demonstrated the therapeutic role of engineered CM in brain tumors and the tumor-suppressing action of extracellular histone H4. The result sheds light on the potential CM-based therapy for breast cancer-associated brain metastases in a minimally invasive manner.

NETosis Markers in Pregnancy: Effects Differ According to Histone Subtypes

NETosis is an innate immune response occurring after infection or inflammation: activated neutrophils expel decondensed DNA in complex with histones into the extracellular environment in a controlled manner. It activates coagulation and fuels the risk of thrombosis. Human pregnancy is associated with a mild proinflammatory state characterized by circulatory neutrophil activation which is further increased in complicated pregnancies, placenta-mediated complications being associated with an increased thrombotic risk. This aberrant activation leads to an increased release of nucleosomes in the blood flow. The aim of our study was to initially quantify nucleosome-bound histones in normal pregnancy and in placenta-mediated complication counterpart. We analyzed the role of histones on extravillous trophoblast function. Circulating nucleosome-bound histones H3 (Nu.QH3.1, Nu.QH3PanCit, Nu.QH3K27me3) and H4 (Nu.QH4K16Ac) were increased in complicated pregnancies. In vitro using the extravillous cell line HTR-8/SVNeo, we observed that free recombinant H2B, H3, and H4 inhibited migration in wound healing assay, but only H3 also blocked invasion in Matrigel-coated Transwell experiments. H3 and H4 also induced apoptosis, whereas H2B did not. Finally, the negative effects of H3 on invasion and apoptosis could be restored with enoxaparin, a low-molecular-weight heparin (LMWH), but not with aspirin. Different circulating nucleosome-bound histones are increased in complicated pregnancy and this would affect migration, invasion, and induce apoptosis of extravillous trophoblasts. Histones might be part of the link between the risk of thrombosis and pregnancy complications, with an effect of LMWH on both.

Therapeutic Potential of Endothelial Colony-Forming Cells in Ischemic Disease: Strategies to Improve their Regenerative Efficacy

Cardiovascular disease (CVD) comprises a range of major clinical cardiac and circulatory diseases, which produce immense health and economic burdens worldwide. Currently, vascular regenerative surgery represents the most employed therapeutic option to treat ischemic disorders, even though not all the patients are amenable to surgical revascularization. Therefore, more efficient therapeutic approaches are urgently required to promote neovascularization. Therapeutic angiogenesis represents an emerging strategy that aims at reconstructing the damaged vascular network by stimulating local angiogenesis and/or promoting de novo blood vessel formation according to a process known as vasculogenesis. In turn, circulating endothelial colony-forming cells (ECFCs) represent truly endothelial precursors, which display high clonogenic potential and have the documented ability to originate de novo blood vessels in vivo. Therefore, ECFCs are regarded as the most promising cellular candidate to promote therapeutic angiogenesis in patients suffering from CVD. The current briefly summarizes the available information about the origin and characterization of ECFCs and then widely illustrates the preclinical studies that assessed their regenerative efficacy in a variety of ischemic disorders, including acute myocardial infarction, peripheral artery disease, ischemic brain disease, and retinopathy. Then, we describe the most common pharmacological, genetic, and epigenetic strategies employed to enhance the vasoreparative potential of autologous ECFCs by manipulating crucial pro-angiogenic signaling pathways, e.g., extracellular-signal regulated kinase/Akt, phosphoinositide 3-kinase, and Ca²⁺ signaling. We conclude by discussing the possibility of targeting circulating ECFCs to rescue their dysfunctional phenotype and promote neovascularization in the presence of CVD.

VIP conditions human endometrial receptivity by privileging endoplasmic reticulum stress through ATF6α pathway

Endometrial stromal cells undergo endoplasmic reticulum (ER) stress and unfolded protein response (UPR) during the decidualization linked with the inflammation and angiogenesis processes. Considering VIP (vasoactive intestinal peptide) induces the decidualization program, we studied whether modulates the ER/UPR pathways to condition both processes for embryo implantation. When Human Endometrial Stromal Cell line (HESC) were decidualized by VIP we observed an increased expression of ATF6α, an ER stress-sensor, and UPR markers, associated with an increase in IL-1β production. Moreover, AEBSF (ATF6α -inhibitor pathway) prevented this effect and decreased the expansion index in the in vitro model of implantation. VIP-decidualized cells also favor angiogenesis accompanied by a strong downregulation in thrombospondin-1. Finally, ATF6α, VIP and VPAC2-receptor expression were reduced in endometrial biopsies from women with recurrent implantation failures in comparison with fertile. In conclusion, VIP privileged ATF6α-pathway associated with a sterile inflammatory response and angiogenesis that might condition endometrial receptivity.

Ceramide 1-Phosphate Protects Endothelial Colony–Forming Cells From Apoptosis and Increases Vasculogenesis In Vitro and In Vivo

Objective:

Ceramide 1-phosphate (C1P) is a bioactive sphingolipid highly augmented in damaged tissues. Because of its abilities to stimulate migration of murine bone marrow–derived progenitor cells, it has been suggested that C1P might be involved in tissue regeneration. In the present study, we aimed to investigate whether C1P regulates survival and angiogenic activity of human progenitor cells with great therapeutic potential in regenerative medicine such as endothelial colony–orming cells (ECFCs).

Approach and Results:

C1P protected ECFC from TNFα (tumor necrosis factor-α)-induced and monosodium urate crystal–induced death and acted as a potent chemoattractant factor through the activation of ERK1/2 (extracellular signal-regulated kinases 1 and 2) and AKT pathways. C1P treatment enhanced ECFC adhesion to collagen type I, an effect that was prevented by β1 integrin blockade, and to mature endothelial cells, which was mediated by the E-selectin/CD44 axis. ECFC proliferation and cord-like structure formation were also increased by C1P, as well as vascularization of gel plug implants loaded or not with ECFC. In a murine model of hindlimb ischemia, local administration of C1P alone promoted blood perfusion and reduced necrosis in the ischemic muscle. Additionally, the beneficial effects of ECFC infusion after ischemia were amplified by C1P pretreatment, resulting in a further and significant enhancement of leg reperfusion and muscle repair.

Conclusions:

Our findings suggest that C1P may have therapeutic relevance in ischemic disorders, improving tissue repair by itself, or priming ECFC angiogenic responses such as chemotaxis, adhesion, proliferation, and tubule formation, which result in a better outcome of ECFC-based therapy.

Neutrophil Extracellular Traps Exert Potential Cytotoxic and Proinflammatory Effects in the Dental Pulp

INTRODUCTION

Neutrophil extracellular traps (NETs) are an important innate immune mechanism aimed at limiting the dissemination of bacteria within tissues and localizing antibacterial killing mechanisms. There is significant interest in the role of NETs in a range of infectious and inflammatory diseases; however, their role in diseased pulp has yet to be explored. Our aim was to determine their relevance to infected pulp and how their components affect human dental pulp cell (HDPC) responses.

METHODS

Diseased pulp tissue was stained for the presence of extracellular DNA and elastase to detect the presence of NETs. Bacteria known to infect pulp were also assayed to determine their ability to stimulate NETs. Coculture studies and NET component challenge were used to determine the effect of extracellular NET release on HDPC viability and inflammatory response. NET-stimulated HDPC secretomes were assessed for their chemotactic activity for lymphocytes and macrophages.

RESULTS

Data indicate that NETs are present in infected pulp tissue and whole NETs, and their histone components, particularly H2A, decreased HDPC viability and stimulated chemokine release, resulting in an attraction of lymphocyte populations.

CONCLUSIONS

NETs are likely important in pulpal pathogenesis with injurious and chronic inflammatory effects on HDPCs, which may contribute to disease progression. Macrophages are chemoattracted to NET-induced apoptotic HDPCs, facilitating cellular debris removal. NETs and histones may provide novel prognostic markers and/or therapeutic targets for pulpal diseases.

New strategies for treatment of infectious sepsis

In this mini review, we describe the molecular mechanisms in polymicrobial sepsis that lead to a series of adverse events including activation of inflammatory and prothrombotic pathways, a faulty innate immune system, and multiorgan dysfunction. Complement activation is a well-established feature of sepsis, especially involving generation of C5a and C5b-9, along with engagement of relevant receptors for C5a. Activation of neutrophils by C5a leads to extrusion of DNA, forming neutrophil extracellular traps that contain myeloperoxidase and oxidases, along with extracellular histones. Generation of the distal complement activation product, C5b-9 (known as the membrane attack complex, MAC), also occurs in sepsis. C5b-9 activates the NLRP3 inflammasome, which damages mitochondria, together with appearance in plasma of IL-1β and IL-18. Histones are strongly proinflammatory as well as being prothrombotic, leading to activation of platelets and development of venous thrombosis. Multiorgan dysfunction is also a feature of sepsis. It is well known that septic cardiomyopathy, which if severe, can lead to death. This complication in sepsis is linked to reduced levels in cardiomyocytes of three critical proteins (SERCA2, NCX, Na⁺ /K⁺ -ATPase). The reductions in these three key proteins are complement- and histone-dependent. Dysfunction of these ATPases is linked to the cardiomyopathy of sepsis. These data suggest novel targets in the setting of sepsis in humans.

Exosomes Derived from Human Primary and Metastatic Colorectal Cancer Cells Contribute to Functional Heterogeneity of Activated Fibroblasts by Reprogramming Their Proteome

Cancer-associated fibroblasts (CAFs) are a heterogeneous population of activated fibroblasts that constitute a dominant cellular component of the tumor microenvironment (TME) performing distinct functions. Here, the role of tumor-derived exosomes (Exos) in activating quiescent fibroblasts into distinct functional subtypes is investigated. Proteomic profiling and functional dissection reveal that early- (SW480) and late-stage (SW620) colorectal cancer (CRC) cell-derived Exos both activated normal quiescent fibroblasts (α-SMA^- , CAV⁺ , FAP⁺ , VIM⁺ ) into CAF-like fibroblasts (α-SMA⁺ , CAV^- , FAP⁺ , VIM⁺ ). Fibroblasts activated by early-stage cancer-exosomes (SW480-Exos) are highly pro-proliferative and pro-angiogenic and display elevated expression of pro-angiogenic (IL8, RAB10, NDRG1) and pro-proliferative (SA1008, FFPS) proteins. In contrast, fibroblasts activated by late-stage cancer-exosomes (SW620-Exos) display a striking ability to invade through extracellular matrix through upregulation of pro-invasive regulators of membrane protrusion (PDLIM1, MYO1B) and matrix-remodeling proteins (MMP11, EMMPRIN, ADAM10). Conserved features of Exos-mediated fibroblast activation include enhanced ECM secretion (COL1A1, Tenascin-C/X), oncogenic transformation, and metabolic reprogramming (downregulation of CAV-1, upregulation of glycogen metabolism (GAA), amino acid biosynthesis (SHMT2, IDH2) and membrane transporters of glucose (GLUT1), lactate (MCT4), and amino acids (SLC1A5/3A5)). This study highlights the role of primary and metastatic CRC tumor-derived Exos in generating phenotypically and functionally distinct subsets of CAFs that may facilitate tumor progression.

Extracellular Histones Activate Plasma Membrane Toll-Like Receptor 9 to Trigger Calcium Oscillations in Rat Pancreatic Acinar Tumor Cell AR4-2J

In acute pancreatitis, histones are released by infiltrating neutrophils, but how histones modulate pancreatic acinar cell function has not been investigated. We have examined histone modulation of rat pancreatic acini and pancreatic acinar tumor cell AR4-2J by calcium imaging. Histones were found to have no effect on calcium in pancreatic acini but blocked calcium oscillations induced by cholecystokinin or acetylcholine. Both mixed (Hx) and individual (H1, H2A, H2B, H3, H4) histones induced calcium oscillations in AR4-2J. RT-PCR and Western blot verified the expression of histone-targeted Toll-like receptor (TLR) 2, 4 and 9. Immunocytochemistry identified TLR2/TLR4 on apical plasma membrane and TLR9 in zymogen granule regions in pancreatic acini. TLR2 was found on neighboring and TLR9 on peripheral plasma membranes, but TLR4 was in the nucleus in AR4-2J clusters. Neither TLR2 agonist zymosan-A nor TLR4 agonist lipopolysaccharide had any effect on calcium, but TLR9 agonist ODN1826 induced calcium oscillations; TLR9 antagonist ODN2088 blocked H4-induced calcium oscillations in AR4-2J, which also disappeared after treatment of AR4-2J with glucocorticoid dexamethasone, with concurrent TLR9 migration from plasma membrane to cell interiors. TLR9 down regulation with siRNA suppressed H4-induced calcium oscillations. These data together suggest that extracellular histones activate plasma membrane TLR9 to trigger calcium oscillations in AR4-2J cells.

Extracellular histones indicate the prognosis in patients undergoing extracorporeal membrane oxygenation therapy

Introduction:

Extracellular histones have been recently identified as damage-associated molecular-pattern (DAMP) molecules involved with the pathogenesis of various inflammatory diseases. This study intended to investigate whether extracellular histones can indicate the prognosis in critically ill patients supported by extracorporeal membrane oxygenation (ECMO) therapy.

Methods:

A total of 56 patients undergoing ECMO were analysed retrospectively. Median concentrations of extracellular histones in patients before ECMO were assessed and used to divide the patients into two groups (Group 1 <48 µg/ml and Group 2 ⩾48 µg/ml). Mortality rate, Sequential Organ Failure Assessment (SOFA) scores and systemic inflammation were compared between the groups.

Results:

There were relatively higher concentrations of extracellular histones in Group 2 patients (57.78 µg/ml [48.4, 71.3]) than in Group 1 patients (36.76 µg/ml [28.5, 39.3], p<0.0001). The hospital mortality rate was 55.4% for the entire study subjects, with significantly worsened mortality in Group 2 in contrast to Group 1 (58.8% vs. 50%, p=0.031). Moreover, Group 2 patients had significantly higher SOFA scores and more pronounced systemic inflammation than Group 1 patients prior to ECMO initialization.

Conclusions:

Extracellular histones are known contributors to cell damage and organ injury. Our study showed that extracellular histones have a predictive value in the assessment of outcome of patients undergoing ECMO therapy and may be helpful for risk stratification in clinical settings.

Molecular actions of heparin and their implications in preventing pre-eclampsia

Pre-eclampsia, a hypertensive disorder of pregnancy, continues to be a significant cause of global maternal morbidity. Low-dose aspirin remains the only standard-of-care prophylactic therapy for preventing pre-eclampsia, but is limited in efficacy. Heparin and its derivatives may further enhance the efficacy of aspirin therapy to prevent pre-eclampsia, but the mechanisms mediating this augmentative effect are not known. Although heparin is an anticoagulant agent, it also possesses many anticoagulant-independent properties that may be relevant in the prevention of pre-eclampsia, including effects on placental, vascular and inflammatory function. This review summarizes the non-anticoagulant properties of heparin, and extrapolates how these actions may influence the trajectory of pre-eclampsia pathogenesis as a means of pathway-specific therapy.

Acidic preconditioning of endothelial colony-forming cells (ECFC) promote vasculogenesis under proinflammatory and high glucose conditions in vitro and in vivo

Background

We have previously demonstrated that acidic preconditioning of human endothelial colony-forming cells (ECFC) increased proliferation, migration, and tubulogenesis in vitro, and increased their regenerative potential in a murine model of hind limb ischemia without baseline disease. We now analyze whether this strategy is also effective under adverse conditions for vasculogenesis, such as the presence of ischemia-related toxic molecules or diabetes, one of the main target diseases for cell therapy due to their well-known healing impairments.

Methods

Cord blood-derived CD34⁺ cells were seeded in endothelial growth culture medium (EGM2) and ECFC colonies were obtained after 14–21 days. ECFC were exposed at pH 6.6 (preconditioned) or pH 7.4 (nonpreconditioned) for 6 h, and then pH was restored at 7.4. A model of type 2 diabetes induced by a high-fat and high-sucrose diet was developed in nude mice and hind limb ischemia was induced in these animals by femoral artery ligation. A P value < 0.05 was considered statistically significant (by one-way analysis of variance).

Results

We found that acidic preconditioning increased ECFC adhesion and the release of pro-angiogenic molecules, and protected ECFC from the cytotoxic effects of monosodium urate crystals, histones, and tumor necrosis factor (TNF)α, which induced necrosis, pyroptosis, and apoptosis, respectively. Noncytotoxic concentrations of high glucose, TNFα, or their combination reduced ECFC proliferation, stromal cell-derived factor (SDF)1-driven migration, and tubule formation on a basement membrane matrix, whereas almost no inhibition was observed in preconditioned ECFC. In type 2 diabetic mice, intravenous administration of preconditioned ECFC significantly induced blood flow recovery at the ischemic limb as measured by Doppler, compared with the phosphate-buffered saline (PBS) and nonpreconditioned ECFC groups. Moreover, the histologic analysis of gastrocnemius muscles showed an increased vascular density and reduced signs of inflammation in the animals receiving preconditioned ECFC.

Conclusions

Acidic preconditioning improved ECFC survival and angiogenic activity in the presence of proinflammatory and damage signals present in the ischemic milieu, even under high glucose conditions, and increased their therapeutic potential for postischemia tissue regeneration in a murine model of type 2 diabetes. Collectively, our data suggest that acidic preconditioning of ECFC is a simple and inexpensive strategy to improve the effectiveness of cell transplantation in diabetes, where tissue repair is highly compromised.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0872-7) contains supplementary material, which is available to authorized users.

Yoder M, Majluf-Cruz A, Alvarado-Moreno JA. Reduced proliferation of endothelial colony-forming cells in unprovoked venous thromboembolic disease as a consequence of endothelial dysfunction

BACKGROUND

Venous thromboembolic disease (VTD) is a public health problem. We recently reported that endothelial colony-forming cells (ECFCs) derived from endothelial cells (EC) (ECFC-ECs) from patients with VTD have a dysfunctional state. For this study, we proposed that a dysfunctional status of these cells generates a reduction of its proliferative ability, which is also associated with senescence and reactive oxygen species (ROS).

METHODS AND RESULTS

Human mononuclear cells (MNCs) were obtained from peripheral blood from 40 healthy human volunteers (controls) and 50 patients with VTD matched by age (20-50 years) and sex to obtain ECFCs. We assayed their proliferative ability with plasma of patients and controls and supernatants of cultures from ECFC-ECs, senescence-associated β-galactosidase (SA-β-gal), ROS, and expression of ephrin-B2/Eph-B4 receptor. Compared with cells from controls, cells from VTD patients showed an 8-fold increase of ECFCs that emerged 1 week earlier, reduced proliferation at long term (39%) and, in passages 4 and 10, a highly senescent rate (30±1.05% vs. 91.3±15.07%, respectively) with an increase of ROS and impaired expression of ephrin-B2/Eph-4 genes. Proliferation potential of cells from VTD patients was reduced in endothelial medium [1.4±0.22 doubling population (DP)], control plasma (1.18±0.31 DP), or plasma from VTD patients (1.65±0.27 DP).

CONCLUSIONS

As compared with controls, ECFC-ECs from individuals with VTD have higher oxidative stress, proliferation stress, cellular senescence, and low proliferative potential. These findings suggest that patients with a history of VTD are ECFC-ECs dysfunctional that could be associated to permanent risk for new thrombotic events.

A new mass spectrometry-based method for the quantification of histones in plasma from septic shock patients

The aim of this study was to develop a novel method to detect circulating histones H3 and H2B in plasma based on multiple reaction monitoring targeted mass spectrometry and a multiple reaction monitoring approach (MRM-MS) for its clinical application in critical bacteriaemic septic shock patients. Plasma samples from 17 septic shock patients with confirmed bacteraemia and 10 healthy controls were analysed by an MRM-MS method, which specifically detects presence of histones H3 and H2B. By an internal standard, it was possible to quantify the concentration of circulating histones in plasma, which were significantly higher in patients, and thus confirmed their potential as biomarkers for diagnosing septic shock. After comparing surviving patients and non-survivors, a correlation was found between higher levels of circulating histones and unfavourable outcome. Indeed, histone H3 proved a more efficient and sensitive biomarker for septic shock prognosis. In conclusion, these findings suggest the accuracy of the MRM-MS technique and stable isotope labelled peptides to detect and quantify circulating plasma histones H2B and H3. This method may be used for early septic shock diagnoses and for the prognosis of fatal outcomes.

Presence of Cytotoxic Extracellular Histones in Machine Perfusate of Donation After Circulatory Death Kidneys

BACKGROUND

Extracellular histones are cytotoxic molecules that are related to cell stress and death. They have been shown to play a crucial role in multiple pathophysiologic processes like sepsis, inflammation, vascular dysfunction, and thrombosis. Their role in organ donation and graft function and survival is still unknown. The aim of this study was to assess whether an association exists between the presence of extracellular histones in machine perfusates and deceased donor kidney viability.

METHODS

Machine perfusates of 390 donations after circulatory death kidneys were analyzed for histone concentration, and corresponding graft function and survival were assessed.

RESULTS

Extracellular histone concentrations were significantly higher in perfusates of kidneys with posttransplant graft dysfunction (primary nonfunction and delayed graft function) and were an independent risk factor for delayed graft function (odds ratio, 2.152; 95% confidence interval [95% CI], 1.199-3.863) and 1 year graft failure (hazard ratio, 1.386; 95% CI, 1.037-1.853), but not for primary nonfunction (odds ratio, 1.342; 95% CI, 0.900-2.002). One year graft survival was 12% higher in the group with low histone concentrations (P = 0.008) as compared with the group that contained higher histone concentrations.

CONCLUSIONS

This study warrants future studies to probe for a possible role of cytotoxic extracellular histones in organ viability and suggests that quantitation of extracellular histones might contribute to assessment of posttransplant graft function and survival.

Conservative Mechanisms of Extracellular Trap Formation by Annelida Eisenia andrei: Serine Protease Activity Requirement

Formation of extracellular traps (ETs) capturing and immobilizing pathogens is now a well-established defense mechanism added to the repertoire of vertebrate phagocytes. These ETs are composed of extracellular DNA (extDNA), histones and antimicrobial proteins. Formation of mouse and human ETs depends on enzymes (i) facilitating decondensation of chromatin by citrullination of histones, and (ii) serine proteases degrading histones. In invertebrates, initial reports revealed existence of ETs composed of extDNA and histones, and here we document for the first time that also coelomocytes, immunocompetent cells of an earthworm Eisenia andrei, cast ETs which successfully trap bacteria in a reactive oxygen species (ROS)-dependent and -independent manner. Importantly, the formation of ETs was observed not only when coelomocytes were studied ex vivo, but also in vivo, directly in the earthworm coelom. These ETs were composed of extDNA, heat shock proteins (HSP27) and H3 histones. Furthermore, the formation of E. andrei ETs depended on activity of serine proteases, including elastase-like activity. Moreover, ETs interconnected and hold together aggregating coelomocytes, a processes proceeding encapsulation. In conclusion, the study confirms ET formation by earthworms, and unravels mechanisms leading to ET formation and encapsulation in invertebrates.