Thrombin receptor PAR-1 activation on endothelial progenitor cells enhances chemotaxis-associated genes expression and leukocyte recruitment by a COX-2-dependent mechanism

A Review Into the Insights of the Role of Endothelial Progenitor Cells on Bone Biology

In addition to its important transport functions, the skeletal system is involved in complex biological activities for the regulation of blood vessels. Endothelial progenitor cells (EPCs), as stem cells of endothelial cells (ECs), possess an effective proliferative capacity and a powerful angiogenic capacity prior to their differentiation. They demonstrate synergistic effects to promote bone regeneration and vascularization more effectively by co-culturing with multiple cells. EPCs demonstrate a significant therapeutic potential for the treatment of various bone diseases by secreting a combination of growth factors, regulating cellular functions, and promoting bone regeneration. In this review, we retrospect the definition and properties of EPCs, their interaction with mesenchymal stem cells, ECs, smooth muscle cells, and immune cells in bone regeneration, vascularization, and immunity, summarizing their mechanism of action and contribution to bone biology. Additionally, we generalized their role and potential mechanisms in the treatment of various bone diseases, possibly indicating their clinical application.

Thromboprophylaxis with argatroban in critically ill patients with sepsis: a review

During sepsis, an initial prothrombotic shift takes place, in which coagulatory acute-phase proteins are increased, while anticoagulatory factors and platelet count decrease. Further on, the fibrinolytic system becomes impaired, which contributes to disease severity. At a later stage in sepsis, coagulation factors may become depleted, and sepsis patients may shift into a hypo-coagulable state with an increased bleeding risk. During the pro-coagulatory shift, critically ill patients have an increased thrombosis risk that ranges from developing micro-thromboses that impair organ function to life-threatening thromboembolic events. Here, thrombin plays a key role in coagulation as well as in inflammation. For thromboprophylaxis, low molecular weight heparins (LMWH) and unfractionated heparins (UFHs) are recommended. Nevertheless, there are conditions such as heparin resistance or heparin-induced thrombocytopenia (HIT), wherein heparin becomes ineffective or even puts the patient at an increased prothrombotic risk. In these cases, argatroban, a direct thrombin inhibitor (DTI), might be a potential alternative anticoagulatory strategy. Yet, caution is advised with regard to dosing of argatroban especially in sepsis. Therefore, the starting dose of argatroban is recommended to be low and should be titrated to the targeted anticoagulation level and be closely monitored in the further course of treatment. The authors of this review recommend using DTIs such as argatroban as an alternative anticoagulant in critically ill patients suffering from sepsis or COVID-19 with suspected or confirmed HIT, HIT-like conditions, impaired fibrinolysis, in patients on extracorporeal circuits and patients with heparin resistance, when closely monitored.

Cyclosporine A and Tacrolimus Induce Functional Impairment and Inflammatory Reactions in Endothelial Progenitor Cells

Immunosuppressants are a mandatory therapy for transplant patients to avoid rejection of the transplanted organ by the immune system. However, there are several known side effects, including alterations of the vasculature, which involve a higher occurrence of cardiovascular events. While the effects of the commonly applied immunosuppressive drugs cyclosporine A (CsA) and tacrolimus (Tac) on mature endothelial cells have been addressed in several studies, we focused our research on the unexplored effects of CsA and Tac on endothelial colony-forming cells (ECFCs), a subgroup of endothelial progenitor cells, which play an important role in vascular repair and angiogenesis. We hypothesized that CsA and Tac induce functional defects and activate an inflammatory cascade via NF-κB signaling in ECFCs. ECFCs were incubated with different doses (0.01 µM–10 µM) of CsA or Tac. ECFC function was determined using in vitro models. The expression of inflammatory cytokines and adhesion molecules was explored by quantitative real-time PCR and flow cytometry. NF-κB subunit modification was assessed by immunoblot and immunofluorescence. CsA and Tac significantly impaired ECFC function, including proliferation, migration, and tube formation. TNF-α, IL-6, VCAM, and ICAM mRNA expression, as well as PECAM and VCAM surface expression, were enhanced. Furthermore, CsA and Tac led to NF-κB p65 subunit phosphorylation and nuclear translocation. Pharmacological inhibition of NF-κB by parthenolide diminished CsA- and Tac-mediated proinflammatory effects. The data of functional impairment and activation of inflammatory signals provide new insight into mechanisms associated with CsA and Tac and cardiovascular risk in transplant patients.

Valproic Acid Decreases Endothelial Colony Forming Cells Differentiation and Induces Endothelial-to-Mesenchymal Transition-like Process

Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor is a widely used anticonvulsant drug. VPA is also under clinical evaluation to be employed in anticancer therapy, as an antithrombotic agent or a molecule to be used in the stem cells expansion protocols. Since endothelial colony forming cells (ECFC) has been identified as the human postnatal vasculogenic cells involved in thrombotic disorders and serve as a promising source of immature cell for vascular repair, objectives of the present study were to determine how VPA contributes to ECFC commitment and their angiogenic properties. We examined the effect of VPA on ECFC obtained from cord blood by evaluating colony number, proliferation, migration and their sprouting ability in vitro, as well as their in vivo vasculogenic properties. VPA inhibited endothelial differentiation potential from of cord blood derived stem cells associated with decreased proliferation and sprouting activity of cultured ECFC. VPA treatment significantly decreased the vessel-forming ability of ECFC transplanted together with mesenchymal stem cells (MSC) in Matrigel implants in nude mice model. Surprisingly, a microscopic evaluation revealed that VPA induces marked morphological changes from a cobblestone-like EC morphology to enlarged spindle shaped morphology of ECFC. RT-qPCR and a CD31/CD90 flow cytometry analysis confirmed a phenotypic switch of VPA-treated ECFC to mesenchymal-like phenotype. In conclusion, the pan-HDAC inhibitor VPA described for expansion of hematopoietic stem cells and very small embryonic like stem cells cannot be successfully employed for differentiation of endothelial lineage committed ECFC into functional endothelial cells. Our data also suggest that VPA based therapeutics may induce endothelial dysfunction associated with fibrosis that might induce thrombosis recurrence or venous insufficiency.

Insights into the Effects of Dietary Omega-6/Omega-3 Polyunsaturated Fatty Acid (PUFA) Ratio on Oxidative Metabolic Pathways of Oncological Bone Disease and Global Health

Various nutrients have been designated as antioxidants, with a possible effect on diseases like cancer. This is partly due to their effect on prostaglandins, thereby affecting local pathological metabolic acidosis. This paper aims to summarize the culprit pathophysiological mechanisms involved, with a focus on the bone microenvironment. The omega- 6/omega-3 PUFA ratio is particularly investigated for its antioxidative effects, countering these pathways to fight the disease. This feature is looked at concerning its impact on health in general, with a particular focus on malignant bone metastasis.

Interleukin-8 Receptors CXCR1 and CXCR2 Are Not Expressed by Endothelial Colony-forming Cells

Endothelial colony-forming cells (ECFCs) are human vasculogenic cells described as potential cell therapy product and good candidates for being a vascular liquid biopsy. Since interleukin-8 (IL-8) is a main actor in senescence, its ability to interact with ECFCs has been explored. However, expression of CXCR1 and CXCR2, the two cellular receptors for IL-8, by ECFCs remain controversial as several teams published contradictory reports. Using complementary technical approaches, we have investigated the presence of these receptors on ECFCs isolated from cord blood. First, CXCR1 and CXCR2 were not detected on several clones of cord blood- endothelial colony-forming cell using different antibodies available, in contrast to well-known positive cells. We then compared the RT-PCR primers used in different papers to search for the presence of CXCR1 and CXCR2 mRNA and found that several primer pairs used could lead to non-specific DNA amplification. Last, we confirmed those results by RNA sequencing. CXCR1 and CXCR2 were not detected in ECFCs in contrary to human-induced pluripotent stem cell-derived endothelial cells (h-iECs). In conclusion, using three different approaches, we confirmed that CXCR1 and CXCR2 were not expressed at mRNA or protein level by ECFCs. Thus, IL-8 secretion by ECFCs, its effects in angiogenesis and their involvement in senescent process need to be reanalyzed according to this absence of CXCR-1 and - 2 in ECFCs.Graphical Abstract.

The multifaceted role of plasminogen in inflammation

A fine-tuned activation and deactivation of proteases and their inhibitors are involved in the execution of the inflammatory response. The zymogen/proenzyme plasminogen is converted to the serine protease plasmin, a key fibrinolytic factor by plasminogen activators including tissue-type plasminogen activator (tPA). Plasmin is part of an intricate protease network controlling proteins of initial hemostasis/coagulation, fibrinolytic and complement system. Activation of these protease cascades is required to mount a proper inflammatory response. Although best known for its ability to dissolve clots and cleave fibrin, recent studies point to the importance of fibrin-independent functions of plasmin during acute inflammation and inflammation resolution. In this review, we provide an up-to-date overview of the current knowledge of the enzymatic and cytokine-like effects of tPA and describe the role of tPA and plasminogen receptors in the regulation of the inflammatory response with emphasis on the cytokine storm syndrome such as observed during coronavirus disease 2019 or macrophage activation syndrome. We discuss tPA as a modulator of Toll like receptor signaling, plasmin as an activator of NFkB signaling, and summarize recent studies on the role of plasminogen receptors as controllers of the macrophage conversion into the M2 type and as mediators of efferocytosis during inflammation resolution.

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.

MicroRNAs As Master Regulators of Atherosclerosis: From Pathogenesis to Novel Therapeutic Options

Significance: Cardiovascular disease (CVD) remains the major cause of morbidity and mortality worldwide. Accumulating evidence indicates that atherosclerosis and its sequelae, coronary artery disease, contribute to the majority of cardiovascular deaths. Atherosclerosis is a chronic inflammatory disease of the arteries in which atherosclerotic plaques form within the vessel wall. Epidemiological studies have identified various risk factors for atherosclerosis, such as diabetes, hyperlipidemia, smoking, genetic predisposition, and sedentary lifestyle. Recent Advances: Through the advancement of genetic manipulation techniques and their use in cardiovascular biology, it was shown that small RNAs, especially microRNAs (miRNAs), are dynamic regulators of disease pathogenesis. They are considered to be central during the regulation of gene expression through numerous mechanisms and provide a means to develop biomarkers and therapeutic tools for the diagnosis and therapy of atherosclerosis. Circulating miRNAs encapsulated within membrane-surrounded vesicles, which originate from diverse subcellular compartments, are now emerging as novel regulators of intercellular communication. The miRNAs, in both freely circulating and vesicle-bound forms, represent a valuable tool for diagnosing and monitoring CVD, recently termed as "liquid biopsy." Critical Issues: However, despite the recent advancements in miRNA-based diagnostics and therapeutics, understanding how miRNAs can regulate atherosclerosis is still crucial to achieving an effective intervention and reducing the disease burden. Future Directions: We provide a landscape of the current developmental progression of RNA therapeutics as a holistic approach for treating CVD in different animal models and clinical trials. Future interrogations are warranted for the development of miRNA-based therapeutics to overcome challenges for the treatment of the disease.

Pivotal micro factors associated with endothelial cells

Objective:

Recent studies have shown the important influence of various micro factors on the general biological activity and function of endothelial cells (ECs). Vascular endothelial growth factor (VEGF) and angiogenin (ANG) are classic micro factors that promote proliferation, differentiation, and migration of ECs. The underlying pathophysiological mechanisms and related pathways of these micro factors remain the focus of current research.

Data sources:

An extensive search was undertaken in the PubMed database by using keywords including “micro factors” and “endothelial cell.” This search covered relevant research articles published between January 1, 2007 and December 31, 2018.

Study selection:

Original articles, reviews, and other articles were searched and reviewed for content on micro factors of ECs.

Results:

VEGF and ANG have critical functions in the occurrence, development, and status of the physiological pathology of ECs. Other EC-associated micro factors include interleukin 10, tumor protein P53, nuclear factor kappa B subunit, interleukin 6, and tumor necrosis factor. The results of Gene Ontology analysis revealed that variations were mainly enriched in positive regulation of transcription by the RNA polymerase II promoter, cellular response to lipopolysaccharides, negative regulation of apoptotic processes, external side of the plasma membrane, cytoplasm, extracellular regions, cytokine activity, growth factor activity, and identical protein binding. The results of the Kyoto Encyclopedia of Genes and Genomes analysis revealed that micro factors were predominantly enriched in inflammatory diseases.

Conclusions:

In summary, the main mediators, factors, or genes associated with ECs include VEGF and ANG. The effect of micro factors on ECs is complex and multifaceted. This review summarizes the correlation between ECs and several micro factors.

The multifaceted role of fibrinogen in tissue injury and inflammation

The canonical role of the hemostatic and fibrinolytic systems is to maintain vascular integrity. Perturbations in either system can prompt primary pathological end points of hemorrhage or thrombosis with vessel occlusion. However, fibrin(ogen) and proteases controlling its deposition and clearance, including (pro)thrombin and plasmin(ogen), have powerful roles in driving acute and reparative inflammatory pathways that affect the spectrum of tissue injury, remodeling, and repair. Indeed, fibrin(ogen) deposits are a near-universal feature of tissue injury, regardless of the nature of the inciting event, including injuries driven by mechanical insult, infection, or immunological derangements. Fibrin can modify multiple aspects of inflammatory cell function by engaging leukocytes through a variety of cellular receptors and mechanisms. Studies on the role of coagulation system activation and fibrin(ogen) deposition in models of inflammatory disease and tissue injury have revealed points of commonality, as well as context-dependent contributions of coagulation and fibrinolytic factors. However, there remains a critical need to define the precise temporal and spatial mechanisms by which fibrinogen-directed inflammatory events may dictate the severity of tissue injury and coordinate the remodeling and repair events essential to restore normal organ function. Current research trends suggest that future studies will give way to the identification of novel hemostatic factor-targeted therapies for a range of tissue injuries and disease.

Inhibiting trophoblast PAR-1 overexpression suppresses sFlt-1-induced anti-angiogenesis and abnormal vascular remodeling: a possible therapeutic approach for preeclampsia

STUDY QUESTION

Is it possible to improve vascular remodeling by inhibiting the excessive expression of protease-activated receptor 1 (PAR-1) in trophoblast of abnormal placenta?

SUMMARY ANSWER

Inhibition of trophoblast PAR-1 overexpression may promote placental angiogenesis and vascular remodeling, offering an alternative therapeutic approach for preeclampsia.

WHAT IS KNOWN ALREADY

PAR-1 is high-affinity receptor of thrombin. Thrombin increases sFlt-1 secretion in trophoblast via the activation of PAR-1. It is reported that the expression of both thrombin and PAR-1 expression are increased in placentas of preeclampsia patients compared with normal placentas.

STUDY DESIGN, SIZE, DURATION

Trophoblast cells were transfected with PAR-1 short hairpin RNA (shRNA) or PAR-1 overexpression plasmids in vitro. Tube formation assays and a villus-decidua co-culture system were used to study the effect of PAR-1 inhibition on placental angiogenesis and vascular remodeling, respectively. Placentas from rats with preeclampsia were transfected with PAR-1 shRNA to confirm the effect of inhibiting PAR-1 overexpression in placenta.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The trophoblast cell line HTR-8/SVneo was transfected with PAR-1 shRNA or PAR-1 overexpression plasmids. After 48 h, supernatant was collected and the level of sFlt-1 secretion was measured by ELISA. Human umbilical cord epithelial cells and a villus-decidua co-culture system were treated with conditioned media to study the effect of PAR-1 inhibition on tube formation and villi vascular remodeling. A preeclampsia rat model was established by intraperitoneal injection of L-NAME. Plasmids were injected into the placenta of the preeclampsia rats and systolic blood pressure was measured on Days 15 and 19. The effect of different treatments was evaluated by proteinuria, placental weights, fetal weights and fetal numbers in study and control groups. The level of serum sFlt-1 in rats with preeclampsia was also measured. Changes in the placenta microvessels were studied by histopathological staining.

MAIN RESULTS AND THE ROLE OF CHANCE

PAR-1 shRNA inhibited PAR-1 expression and significantly suppressed sFlt-1 expression in trophoblasts. Soluble Flt-1 level in the supernatant was suppressed by PAR-1 inhibition plasmid transfection and increased by PAR-1 overexpression plasmids (46.93 ± 5.22 vs. 25.21 ± 4.18 vs. 67.84 ± 3.58 ng/ml, P < 0.01). Tube formation assays showed that conditioned media from shPAR-1 transfected cells resulted in an increase in the total number of branching points compared with that of blank controls (P < 0.05). The villus-decidua co-culture system confirmed down-regulation of PAR-1 was conducive to angiogenesis and vascular remodeling. Transfecting placenta with PAR-1 shRNA plasmids improved placental vascular development and ameliorated the symptoms of preeclampsia in rats. After treatment with shRNA, blood pressure was controlled (140.83 ± 1.08 vs. 123.6 ± 1.47 mmHg, P < 0.001) and proteinuria levels were decreased (4.48 ± 0.36 vs. 2.64 ± 0.25 μg/μl, P < 0.01). sFlt-1 protein levels were significantly higher in preeclampsia group than in the control group (1.44 ± 0.33 vs. 2.92 ± 0.85 ng/ml, P < 0.001), but was reduced (0.92 ± 0.06 ng/ml, vs. PE, P < 0.001) in the treatment group. The histopathological changes of the placental microvessels showed that in the preeclampsia group, the number of blood vessels was reduced, while in treatment group, the placental microvasculature was improved (P < 0.001).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Despite our promising results, the evaluation of kidney damage was studied only by proteinuria measurement. Histochemistry of kidney damage will be supplemented in a further study.

WIDER IMPLICATIONS OF THE FINDINGS

The data showed that inhibition of trophoblast PAR-1 overexpression may promote placental angiogenesis and vascular remodeling, potentially offering an alternative therapeutic approach for preeclampsia.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from the National Natural Science Foundation of China (Grant Nos. 81100442 and 81771605 for Y.Z. and 81179584 for L.Z.) and the Hubei Province Health and Family Planning Scientific Research Project (Grant No. WJ2017 M093 for Y.Z.). The authors declare that there is no conflict of interest.

Vasculogenic Stem and Progenitor Cells in Human: Future Cell Therapy Product or Liquid Biopsy for Vascular Disease

New blood vessel formation in adults was considered to result exclusively from sprouting of preexisting endothelial cells, a process referred to angiogenesis. Vasculogenesis, the formation of new blood vessels from endothelial progenitor cells, was thought to occur only during embryonic life. Discovery of adult endothelial progenitor cells (EPCs) in 1997 opened the door for cell therapy in vascular disease. Endothelial progenitor cells contribute to vascular repair and are now well established as postnatal vasculogenic cells in humans. It is now admitted that endothelial colony-forming cells (ECFCs) are the vasculogenic subtype. ECFCs could be used as a cell therapy product and also as a liquid biopsy in several vascular diseases or as vector for gene therapy. However, despite a huge interest in these cells, their tissue and molecular origin is still unclear. We recently proposed that endothelial progenitor could come from very small embryonic-like stem cells (VSELs) isolated in human from CD133 positive cells. VSELs are small dormant stem cells related to migratory primordial germ cells. They have been described in bone marrow and other organs. This chapter discusses the reported findings from in vitro data and also preclinical studies that aimed to explore stem cells at the origin of vasculogenesis in human and then explore the potential use of ECFCs to promote newly formed vessels or serve as liquid biopsy to understand vascular pathophysiology and in particular pulmonary disease and haemostasis disorders.

Endogenous peptides profiles of human infantile hemangioma tissue and their clinical significance for treatment

Endogenous peptides play crucial roles in various biological processes. Their effects on the pathogenesis of human infantile hemangioma remains poorly understood. In this study, we construct a comparative peptidomic profiling between human infantile hemangioma tissue and matched normal skin using liquid chromatography-tandem mass spectrometry. A total of 192 peptides were significantly differentially expressed in human infantile hemangioma tissue, with 182 upregulated, and 10 downregulated peptides between infantile hemangioma tissue and matched normal skin. Performing bioinformatics analysis (Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis), we found that precursor proteins of these differentially expressed peptides correlate with metabolic process, biological regulation, binding, catalytic activity, and pathways in cancer occurring during pathological changes of infantile hemangioma. Furthermore, 89 differentially expressed peptides shared homology with antimicrobial peptides and 13 matched known immunomodulatory peptides based on prediction database. In conclusion, our results reveal significantly altered expression profiles of peptides in human infantile hemangioma tissue. These peptides may participate in the etiology of infantile hemangioma and provide beneficial scheme for clinical treatments.

Protein profiling identified key chemokines that regulate the maintenance of human pluripotent stem cells

Microenvironment (or niche)-providing chemokines regulate many important biological functions of tissue-specific stem cells. However, to what extent chemokines influence human pluripotent stem cells (hPSCs) is not yet completely understood. In this study, we applied protein array to screen chemokines found within the cytokine pool in the culture supernatant of hPSCs. Our results showed that chemokines were the predominant supernatant components, and came from three sources: hPSCs, feeder cells, and culture media. Chemotaxis analysis of IL-8, SDF-1α, and IP-10 suggested that chemokines function as uniform chemoattractants to mediate in vitro migration of the hPSCs. Chemokines mediate both differentiated and undifferentiated states of hPSCs. However, balanced chemokine signaling tends to enhance their stemness in vitro. These results indicate that chemokines secreted from both stem cells and feeder cells are essential to mobilize hPSCs and maintain their stemness.

RNA-Seq analysis of chikungunya virus infection and identification of granzyme A as a major promoter of arthritic inflammation

Chikungunya virus (CHIKV) is an arthritogenic alphavirus causing epidemics of acute and chronic arthritic disease. Herein we describe a comprehensive RNA-Seq analysis of feet and lymph nodes at peak viraemia (day 2 post infection), acute arthritis (day 7) and chronic disease (day 30) in the CHIKV adult wild-type mouse model. Genes previously shown to be up-regulated in CHIKV patients were also up-regulated in the mouse model. CHIKV sequence information was also obtained with up to ≈8% of the reads mapping to the viral genome; however, no adaptive viral genome changes were apparent. Although day 2, 7 and 30 represent distinct stages of infection and disease, there was a pronounced overlap in up-regulated host genes and pathways. Type I interferon response genes (IRGs) represented up to ≈50% of up-regulated genes, even after loss of type I interferon induction on days 7 and 30. Bioinformatic analyses suggested a number of interferon response factors were primarily responsible for maintaining type I IRG induction. A group of genes prominent in the RNA-Seq analysis and hitherto unexplored in viral arthropathies were granzymes A, B and K. Granzyme A^-/- and to a lesser extent granzyme K^-/-, but not granzyme B^-/-, mice showed a pronounced reduction in foot swelling and arthritis, with analysis of granzyme A^-/- mice showing no reductions in viral loads but reduced NK and T cell infiltrates post CHIKV infection. Treatment with Serpinb6b, a granzyme A inhibitor, also reduced arthritic inflammation in wild-type mice. In non-human primates circulating granzyme A levels were elevated after CHIKV infection, with the increase correlating with viral load. Elevated granzyme A levels were also seen in a small cohort of human CHIKV patients. Taken together these results suggest granzyme A is an important driver of arthritic inflammation and a potential target for therapy.

Trial Registration: ClinicalTrials.gov NCT00281294

The largest chikungunya virus (CHIKV) epidemic ever recorded began in 2004 in Africa and spread across Asia reaching Europe and recently the Americas, with millions of cases reported. We undertook a detailed analysis of the mRNA expression profile during acute and chronic arthritis in an adult wild-type mouse model of CHIKV infection and disease. Gene induction profiles showed a high concordance with published human data, providing some validation of the mouse model. The host response was overwhelmingly dominated by type I interferon response genes, even after type I interferon induction was lost. The analysis also provided information on CHIKV RNA, with no adaptive viral genome changes identified. An important goal of the analysis was to identify new players in arthritic inflammation. Granzyme A was prominent in the RNA-Seq data and granzyme A deficient mice showed reduced arthritis, with no effects on viral loads. Arthritic disease could also be ameliorated in wild-type mice with a granzyme A inhibitor. Elevated circulating granzyme A levels were seen in non-human primates infected with CHIKV and in human CHIKV patients. Granzyme A thus emerges to be a major driver of CHIKV-mediated arthritic inflammation and a potential target for anti-inflammatory interventions.

MicroRNAs in the Pathobiology and Therapy of Atherosclerosis

MicroRNAs are short noncoding RNAs, expressed in humans and involved in sequence-specific post-transcriptional regulation of gene expression. They have emerged as key players in a wide array of biological processes, and changes in their expression and/or function have been associated with plethora of human diseases. Atherosclerosis and its related clinical complications, such as myocardial infarction or stroke, represent the leading cause of death in the Western world. Accumulating experimental evidence has revealed a key role for microRNAs in regulating cellular and molecular processes related to atherosclerosis development, ranging from risk factors, to plaque initiation and progression, up to atherosclerotic plaque rupture. In this review, we focus on how microRNAs can influence atherosclerosis biology, as well as the potential clinical applications of microRNAs, which are being developed as targets as well as therapeutic agents for a growing industry hoping to harness the power of RNA-guided gene regulation to fight disease and infection.

Effect of thrombin preconditioning on migration of subventricular zone-derived cells after intracerebral hemorrhage in rats

OBJECTIVE

To investigate the effect of thrombin preconditioning (TPC) on the intracerebral hemorrhage (ICH)-induced proliferation, migration, and function of subventriclular zone (SVZ) cells and to find new strategies that enhance endogenous neurogenesis after ICH.

METHODS

Male Sprague-Dawley rats were randomly divided into 3 groups (ICH, TPC, and control group). Rats of each group were randomly divided into 5 subgroups (3-d, 7-d, 14-d, 21-d, and 28-d subgroup). ICH was caused by intrastrial stereotactic administration of collagenase type IV. Brdu was used to label newborn SVZ cells. Organotypic brain slices were cultured to dynamically observe the migration of SVZ cells at living brain tissue. Migration of Dil-labeled SVZ cells in living brain slices was traced by time-lapse microscopy. To assess whether SVZ cells migrating to injured striatum had the ability to form synapses with other cells, brain slices from each group were double immunolabeled with Brdu and synapsin I.

RESULTS

The number of Brdu-positive cells markedly increased in the ipsilateral SVZ and striatum 3 days after TPC, peaked at 14 days (P < 0.01), continued to 21 days, and then gradually decreased at 28 days with significant difference compared to the ICH group at each time point (P < 0.01). Migration of Dil-labeled SVZ cells in brain slices in each group was observed and imaged during a 12-h period. Dil-labeled SVZ cells in the TPC group were observed to migrate laterally toward striatum with time with a faster velocity compared to the ICH group (P < 0.01). Our study also demonstrated that TPC induced strong colocalization of Brdu and synapsin I in the ipsilateral striatum between 3 and 28 days after injury.TPC made colocalization of Brdu and synapsin I appear earlier and continue for a longer time compared to the ICH group.

CONCLUSIONS

Our results demonstrated that TPC could promote proliferation, migration, and function of SVZ cells after ICH, which may provide a new idea for enhancing endogenous neurogenesis and developing new therapeutic strategies against ICH-induced brain injury.

Small but smart: MicroRNAs orchestrate atherosclerosis development and progression

MicroRNAs (miRNAs) are short non-coding RNA able to bind specific sequences on target messenger RNAs (mRNAs) and thereby to post-transcriptionally modulate gene expression. Being expressed in all vertebrate cell types, miRNAs have emerged as key players in a wide array of biological processes, including cell proliferation, differentiation and apoptosis. Over the past decade, knowledge concerning the contribution of miRNAs to human pathology has grown with an astonishing pace. In particular, a major involvement of miRNAs in atherosclerosis as a leading cause of global mortality has been supported by ample evidence from in vitro, in vivo and clinical studies. This review aims to summarize and highlight current concepts of miRNA function in the continuum of atherogenesis ranging from risk factors (i.e. dyslipidemia, diabetes, hypertension), to endothelial dysfunction up to the events leading to plaque rupture. Areas in need for further research and potential perspectives for translational applications will be scrutinized. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.