Dicer cleavage by calpain determines platelet microRNA levels and function in diabetes

Platelet-derived microvesicles isolated from type-2 diabetes mellitus patients harbour an altered miRNA signature and drive MDA-MB-231 triple-negative breast cancer cell invasion

The underlying causes of breast cancer are diverse, however, there is a striking association between type 2 diabetes and poor patient outcomes. Platelet activation is a common feature of both type 2 diabetes and breast cancer and has been implicated in tumourigenesis through a multitude of pathways. Here transcriptomic analysis of type 2 diabetes patient-derived platelet microvesicles revealed an altered miRNA signature compared with normoglycaemic control patients. Interestingly, interrogation of these data identifies a shift towards an oncogenic signature in type 2 diabetes-derived platelet microvesicles, with increased levels of miRNAs implicated in breast cancer progression and poor prognosis. Functional studies demonstrate that platelet microvesicles isolated from type 2 diabetes patient blood are internalised by triple-negative breast cancer cells in vitro, and that co-incubation with type 2 diabetes patient-derived platelet microvesicles led to significantly increased expression of epithelial to mesenchymal transition markers and triple-negative breast cancer cell invasion compared with platelet microvesicles from healthy volunteers. Together, these data suggest that circulating PMVs in type 2 diabetes patients may contribute to the progression of triple-negative breast cancer.

Platelet protein synthesis, regulation, and post-translational modifications: mechanics and function

Dogma had been firmly entrenched in the minds of the scientific community that the anucleate mammalian platelet was incapable of protein biosynthesis since their identification in the late 1880s. These beliefs were not challenged until the 1960s when several reports demonstrated that platelets possessed the capacity to biosynthesize proteins. Even then, many still dismissed the synthesis as trivial and unimportant for at least another two decades. Research in the field expanded after the 1980s and numerous reports have since been published that now clearly demonstrate the potential significance of platelet protein synthesis under normal, pathological, and activating conditions. It is now clear that the platelet proteome is not a static entity but can be altered slowly or rapidly in response to external signals to support physiological requirements to maintain hemostasis and other biological processes. All the necessary biological components to support protein synthesis have been identified in platelets along with post-transcriptional processing of mRNAs, regulators of translation, and post-translational modifications such as glycosylation. The last comprehensive review of the subject appeared in 2009 and much work has been conducted since that time. The current review of the field will briefly incorporate the information covered in earlier reviews and then bring the reader up to date with more recent findings.

Platelets and the Atherosclerotic Process: An Overview of New Markers of Platelet Activation and Reactivity, and Their Implications in Primary and Secondary Prevention

The key role played by platelets in the atherosclerosis physiopathology, especially in the acute setting, is ascertained: they are the main actors during thrombus formation and, thus, one of the major investigated elements related to atherothrombotic process involving coronary arteries. Platelets have been studied from different points of view, according with the technology advances and the improvement in the hemostasis knowledge achieved in the last years. Morphology and reactivity constitute the first aspects investigated related to platelets with a significant body of evidence published linking a number of their values and markers to coronary artery disease and cardiovascular events. Recently, the impact of genetics on platelet activation has been explored with promising findings as additional instrument for patient risk stratification; however, this deserves further confirmations. Moreover, the interplay between immune system and platelets has been partially elucidated in the last years, providing intriguing elements that will be basic components for future research to better understand platelet regulation and improve cardiovascular outcome of patients.

Post-transcriptional control of haemostatic genes: mechanisms and emerging therapeutic concepts in thrombo-inflammatory disorders

The haemostatic system is pivotal to maintaining vascular integrity. Multiple components involved in blood coagulation have central functions in inflammation and immunity. A derailed haemostasis is common in prevalent pathologies such as sepsis, cardiovascular disorders, and lately, COVID-19. Physiological mechanisms limit the deleterious consequences of a hyperactivated haemostatic system through adaptive changes in gene expression. While this is mainly regulated at the level of transcription, co- and posttranscriptional mechanisms are increasingly perceived as central hubs governing multiple facets of the haemostatic system. This layer of regulation modulates the biogenesis of haemostatic components, for example in situations of increased turnover and demand. However, they can also be 'hijacked' in disease processes, thereby perpetuating and even causally entertaining associated pathologies. This review summarizes examples and emerging concepts that illustrate the importance of posttranscriptional mechanisms in haemostatic control and crosstalk with the immune system. It also discusses how such regulatory principles can be used to usher in new therapeutic concepts to combat global medical threats such as sepsis or cardiovascular disorders.

The Link between Diabetes, Pancreatic Tumors, and miRNAs-New Players for Diagnosis and Therapy?

Despite significant progress in medicine, pancreatic cancer is one of the most tardily diagnosed cancer and is consequently associated with a poor prognosis and a low survival rate. The asymptomatic clinical picture and the lack of relevant diagnostic markers for the early stages of pancreatic cancer are believed to be the major constraints behind an accurate diagnosis of this disease. Furthermore, underlying mechanisms of pancreatic cancer development are still poorly recognized. It is well accepted that diabetes increases the risk of pancreatic cancer development, however the precise mechanisms are weakly investigated. Recent studies are focused on microRNAs as a causative factor of pancreatic cancer. This review aims to provide an overview of the current knowledge of pancreatic cancer and diabetes-associated microRNAs, and their potential in diagnosis and therapy. miR-96, miR-124, miR-21, and miR-10a were identified as promising biomarkers for early pancreatic cancer prediction. miR-26a, miR-101, and miR-200b carry therapeutic potential, as they not only regulate significant biological pathways, including the TGF-β and PI3K/AKT, but their re-expression contributes to the improvement of the prognosis by reducing invasiveness or chemoresistance. In diabetes, there are also changes in the expression of microRNAs, such as in miR-145, miR-29c, and miR-143. These microRNAs are involved, among others, in insulin signaling, including IRS-1 and AKT (miR-145), glucose homeostasis (hsa-miR-21), and glucose reuptake and gluconeogenesis (miR-29c). Although, changes in the expression of the same microRNAs are observed in both pancreatic cancer and diabetes, they exert different molecular effects. For example, miR-181a is upregulated in both pancreatic cancer and diabetes mellitus, but in diabetes it contributes to insulin resistance, whereas in pancreatic cancer it promotes tumor cell migration, respectively. To conclude, dysregulated microRNAs in diabetes affect crucial cellular processes that are involved in pancreatic cancer development and progression.

MicroRNAs as Biomarkers for Coronary Artery Disease Related to Type 2 Diabetes Mellitus-From Pathogenesis to Potential Clinical Application

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with still growing incidence among adults and young people worldwide. Patients with T2DM are more susceptible to developing coronary artery disease (CAD) than non-diabetic individuals. The currently used diagnostic methods do not ensure the detection of CAD at an early stage. Thus, extensive research on non-invasive, blood-based biomarkers is necessary to avoid life-threatening events. MicroRNAs (miRNAs) are small, endogenous, non-coding RNAs that are stable in human body fluids and easily detectable. A number of reports have highlighted that the aberrant expression of miRNAs may impair the diversity of signaling pathways underlying the pathophysiology of atherosclerosis, which is a key player linking T2DM with CAD. The preclinical evidence suggests the atheroprotective and atherogenic influence of miRNAs on every step of T2DM-induced atherogenesis, including endothelial dysfunction, endothelial to mesenchymal transition, macrophage activation, vascular smooth muscle cells proliferation/migration, platelet hyperactivity, and calcification. Among the 122 analyzed miRNAs, 14 top miRNAs appear to be the most consistently dysregulated in T2DM and CAD, whereas 10 miRNAs are altered in T2DM, CAD, and T2DM-CAD patients. This up-to-date overview aims to discuss the role of miRNAs in the development of diabetic CAD, emphasizing their potential clinical usefulness as novel, non-invasive biomarkers and therapeutic targets for T2DM individuals with a predisposition to undergo CAD.

Platelet-derived microRNA-223 attenuates TNF-α induced monocytes adhesion to arterial endothelium by targeting ICAM-1 in Kawasaki disease

Background

Kawasaki disease (KD) is an acute vasculitis that may result in permanent coronary artery damage with unknown etiology. Endothelial cell (EC) dysfunction and platelet hyperactivity are the hallmarks of KD. Platelets are involved in the development of endothelial dysfunction. MiR-223 transferred by platelet microparticles (PMPs) has been found to involve in the functional regulation of endothelial cells in sepsis. However, the role of platelet-derived miR-223 in endothelial dysfunction has not yet been investigated in KD.

Objectives

We seek to investigate the role of platelet-derived miR-223 in endothelial dysfunction of KD vasculopathy.

Methods and results

Forty-five acute KD patients and 45 matched controls were randomly recruited in the study. When co-cultured with human coronary artery endothelial cells (HCAECs), KD platelets with higher levels of miR-223 were incorporated into HCAECs, resulting in the horizontal transfer of miR-223. Using KD platelets, PMPs, and platelet-releasate from the same amount of blood co-cultured with HCAECs, we found the increased expression of miR-223 in HCAECs was primarily derived from KD platelets, rather than PMPs or free miRNAs from platelet- releasate. KD platelet-derived miR-223 attenuated TNF-α induced intercellular cell adhesion molecule-1 (ICAM-1) expression in HCAECs. KD platelet-derived miR-223 also suppressed the monocyte adhesion to HCAECs. In vivo, platelet-specific miR-223 knockout (PF4-cre: miR-223^flox/flox) C57BL/6 mice and miR-223^flox/flox C57BL/6 mice were used. Using Lactobacillus casei cell wall extract (LCWE) to establish KD murine model, we showed that in LCWE-injected PF4-cre: miR-223^flox/flox mice, deficiency of platelet-miR-223 exacerbates the medial thickening of the abdominal aorta, increased ICAM-1 expression with concomitant CD45⁺ inflammatory cells infiltration into the endothelium compared to LCWE-injected miR-223^flox/flox mice.

Conclusions

The horizontal transfer of platelet-derived miR-223 suppresses the expression of ICAM-1 in HCAECs, which at least in part attenuates leukocyte adhesion, thereby reducing endothelial damage in KD vasculitis

Insights Into Platelet-Derived MicroRNAs in Cardiovascular and Oncologic Diseases: Potential Predictor and Therapeutic Target

Non-communicable diseases (NCDs), represented by cardiovascular diseases and cancer, have been the leading cause of death globally. Improvements in mortality from cardiovascular (CV) diseases (decrease of 14%/100,000, United States) or cancers (increase 7.5%/100,000, United States) seem unsatisfactory during the past two decades, and so the search for innovative and accurate biomarkers of early diagnosis and prevention, and novel treatment strategies is a valuable clinical and economic endeavor. Both tumors and cardiovascular system are rich in angiological systems that maintain material exchange, signal transduction and distant regulation. This pattern determines that they are strongly influenced by circulating substances, such as glycolipid metabolism, inflammatory homeostasis and cyclic non-coding RNA and so forth. Platelets, a group of small anucleated cells, inherit many mature proteins, mRNAs, and non-coding RNAs from their parent megakaryocytes during gradual formation and manifest important roles in inflammation, angiogenesis, atherosclerosis, stroke, myocardial infarction, diabetes, cancer, and many other diseases apart from its classical function in hemostasis. MicroRNAs (miRNAs) are a class of non-coding RNAs containing ∼22 nucleotides that participate in many key cellular processes by pairing with mRNAs at partially complementary binding sites for post-transcriptional regulation of gene expression. Platelets contain fully functional miRNA processors in their microvesicles and are able to transport their miRNAs to neighboring cells and regulate their gene expression. Therefore, the importance of platelet-derived miRNAs for the human health is of increasing interest. Here, we will elaborate systematically the roles of platelet-derived miRNAs in cardiovascular disease and cancer in the hope of providing clinicians with new ideas for early diagnosis and therapeutic strategies.

Non-Traditional Pathways for Platelet Pathophysiology in Diabetes: Implications for Future Therapeutic Targets

Cardiovascular complications remain the leading cause of morbidity and mortality in individuals with diabetes, driven by interlinked metabolic, inflammatory, and thrombotic changes. Hyperglycaemia, insulin resistance/deficiency, dyslipidaemia, and associated oxidative stress have been linked to abnormal platelet function leading to hyperactivity, and thus increasing vascular thrombotic risk. However, emerging evidence suggests platelets also contribute to low-grade inflammation and additionally possess the ability to interact with circulating immune cells, further driving vascular thrombo-inflammatory pathways. This narrative review highlights the role of platelets in inflammatory and immune processes beyond typical thrombotic effects and the impact these mechanisms have on cardiovascular disease in diabetes. We discuss pathways for platelet-induced inflammation and how platelet reprogramming in diabetes contributes to the high cardiovascular risk that characterises this population. Fully understanding the mechanistic pathways for platelet-induced vascular pathology will allow for the development of more effective management strategies that deal with the causes rather than the consequences of platelet function abnormalities in diabetes.

Circulating microRNAs as biomarkers and mediators of platelet activation

Platelets are essential mediators of physiological hemostasis and pathological thrombosis. Currently available tests and markers of platelet activation did not prove successful in guiding treatment decisions for patients with cardiovascular disease, justifying further research into novel markers of platelet reactivity. Platelets contain a variety of microRNAs (miRNAs) and are a major contributor to the extracellular circulating miRNA pool. Levels of platelet-derived miRNAs in the circulation have been associated with different measures of platelet activation as well as antiplatelet therapy and have therefore been implied as potential new markers of platelet reactivity. In contrast to the ex vivo assessment of platelet reactivity by current platelet function tests, miRNA measurements may enable assessment of platelet reactivity in vivo. It remains to be seen however, whether miRNAs may aid clinical diagnostics. Major limitations in the platelet miRNA research field remain the susceptibility to preanalytical variation, non-standardized sample preparation and data normalization that hampers inter-study comparisons. In this review, we provide an overview of the literature on circulating miRNAs as biomarkers of platelet activation, highlighting the underlying biology, the application in patients with cardiovascular disease and antiplatelet therapy and elaborating on technical limitations regarding their quantification in the circulation.

Eight weeks of combined exercise training do not alter circulating microRNAs-29a, -133a, -133b, and -155 in young, healthy men

PURPOSE

Individuals with a family history of type 2 diabetes (FH +) have an increased risk of developing type 2 diabetes. Circulating microRNAs (miRNAs) have been implicated as biomarkers of type 2 diabetes risk. Here, we investigated if four circulating miRNAs related to glucose metabolism were altered in men with a FH + and we conducted a preliminary analysis to determine if miRNA expressions were responsive to 8 weeks of combined exercise training.

METHODS

Sixteen young healthy men (mean ± SD; age 22.5 ± 2.5; BMI 26.4 ± 4.0) with FH + or without a family history of type 2 diabetes (FH -) underweight 8 weeks of combined endurance and resistance exercise training (n = 8 FH -; n = 8 FH +). The expression of miR-29a, miR-133a, miR-133b, and miR-155 were measured in serum before and after exercise training. QIAGEN's Ingenuity^® Pathway Analysis was used to examine miRNA target genes and their involvement in glucose metabolism signaling pathways.

RESULTS

There were no differences in miRNA expressions between FH - and FH + . Exercise training did not alter miRNA expressions in either FH - or FH + despite improvements in insulin sensitivity, aerobic capacity, and muscular strength. miR-29a and miR-155 were inversely related to fasting glucose, and miR-133a and miR-133b were negatively correlated with glucose tolerance; however, correlations were not observed with insulin sensitivity.

CONCLUSIONS

The circulating miRNAs- miR-29a, miR-133a, miR-133b, and miR-155 are related to measures of glucose metabolism in healthy, normoglycemic men, but do not reflect peripheral insulin sensitivity or improvements in metabolic health following 8 weeks of combined exercise training.

Serum miRNA Profile in Diabetic Patients With Ischemic Heart Disease as a Promising Non-Invasive Biomarker

The increasing morbidity and mortality of type 2 diabetic mellitus (T2DM) patients with ischemic heart disease (IHD) highlight an urgent need to identify early biomarkers, which would help to predict individual risk of development of IHD. Here, we postulate that circulating serum-derived micro RNAs (miRNAs) may serve as potential biomarkers for early IHD diagnosis and support the identification of diabetic individuals with a predisposition to undergo IHD. We obtained serum samples from T2DM patients either with IHD or IHD-free and analysed the expression levels of 798 miRNAs using the NanoString nCounter technology platform. The prediction of the putative miRNAs targets was performed using the Ingenuity Pathway Analysis (IPA) software. Gene Ontology (GO) analysis was used to identify the biological function and signalling pathways associated with miRNA target genes. Hub genes of protein-protein interaction (PPI) network were identified by STRING database and Cytotoscape tool. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic value of identified miRNAs. Real-time quantitative polymerase chain reaction (qRT-PCR) was used for nCounter platform data validation. Our data showed that six miRNAs (miR-615-3p, miR-3147, miR-1224-5p, miR-5196-3p, miR-6732-3p, and miR-548b-3p) were significantly upregulated in T2DM IHD patients compared to T2DM patients without IHD. Further analysis indicated that 489 putative target genes mainly affected the endothelin-1 signalling pathway, glucocorticoid biosynthesis, and apelin cardiomyocyte signalling pathway. All tested miRNAs showed high diagnostic value (AUC = 0.779 - 0.877). Taken together, our research suggests that circulating miRNAs might have a crucial role in the development of IHD in diabetic patients and may be used as a potential biomarker for early diagnosis.

miRNA-223 Suppresses Mouse Gallstone Formation by Targeting Key Transporters in Hepatobiliary Cholesterol Secretion Pathway

miRNA-223 has been previously reported to play an essential role in hepatic cholesterol homeostasis. However, its role in regulation of biliary cholesterol secretion and gallstone formation remains unknown. Hence, mice with conventional knockout (KO), hepatocyte-specific knockout (ΔHepa) / knockdown (KD) or gain expression of miRNA-223 were included in the study and were subjected to lithogenic diet (LD) for various weeks. The gall bladders and liver tissues were harvested for cholesterol crystal imaging, gallstone mass measurement and molecular analysis. Levels of cholesterol, bile salt, phospholipids, and triglyceride were determined in serum, liver tissues, and bile by enzyme color reactive assays. A 3' UTR reporter gene assay was used to verify the direct target genes for miRNA-223. LD-induced gallstone formation was remarkably accelerated in miRNA-223 KO, ΔHepa, and KD mice with concurrent enhancement in total cholesterol levels in liver tissues and bile. Key biliary cholesterol transporters ABCG5 and ABCG8 were identified as direct targets of miRNA-223. Reversely, AAV-mediated hepatocyte-specific miRNA-223 overexpression prevented gallstone progression with reduced targets expression. Therefore, the present study demonstrates a novel role of miRNA-223 in the gallstone formation by targeting ABCG5 and ABCG8 and elevating miRNA-223 would be a potentially novel approach to overcome the sternness of cholesterol gallstone disease.

Primary Thrombophilia XVI: A Look at the Genotype of the Sticky Platelet Syndrome Phenotype

The sticky platelet syndrome (SPS) was described by Mammen in 1983. Since then, scientists in several countries have identified the condition and published cases or series of patients, thus enabling the description of the prevalence of the inherited condition, its salient clinical features, and the treatment of the disease. The diagnosis of the SPS phenotype requires fresh blood samples and special equipment which is not available in all coagulation laboratories. In the era of molecular biology, up to now it has not been possible to define a clear association of the SPS phenotype with a specific molecular marker. Some molecular changes which have been described in platelet proteins in some persons with the phenotype of the SPS are here discussed. Nowadays, the SPS phenotype may be considered as a risk factor for thrombosis and most cases of the SPS developing vaso-occlussive episodes are the result of its coexistence with other thrombosis-prone conditions, some of the inherited and some of them acquired, thus leading to the concept of multifactorial thrombophilia. Ignoring all these evidence-based concepts is inappropriate, same as stating that the SPS is a nonentity simply because not all laboratories are endowed with adequate equipment to support the diagnosis.

Secreted modular calcium-binding protein 1 binds and activates thrombin to account for platelet hyperreactivity in diabetes

Secreted modular calcium-binding protein 1 (SMOC1) is an osteonectin/SPARC-related matricellular protein, whose expression is regulated by microRNA-223 (miR-223). Given that platelets are rich in miR-223, this study investigated the expression of SMOC1 and its contribution to platelet function. Human and murine platelets expressed SMOC1, whereas platelets from SMOC1+/- mice did not present detectable mature SMOC1 protein. Platelets from SMOC1+/- mice demonstrated attenuated responsiveness to thrombin (platelet neutrophil aggregate formation, aggregation, clot formation, Ca2+ increase, and β3 integrin phosphorylation), whereas responses to other platelet agonists were unaffected. SMOC1 has been implicated in transforming growth factor-β signaling, but no link to this pathway was detected in platelets. Rather, the SMOC1 Kazal domain directly bound thrombin to potentiate its activity in vitro, as well as its actions on isolated platelets. The latter effects were prevented by monoclonal antibodies against SMOC1. Platelets from miR-223-deficient mice expressed high levels of SMOC1 and exhibited hyperreactivity to thrombin that was also reversed by preincubation with monoclonal antibodies against SMOC1. Similarly, SMOC1 levels were markedly upregulated in platelets from individuals with type 2 diabetes, and the SMOC1 antibody abrogated platelet hyperresponsiveness to thrombin. Taken together, we have identified SMOC1 as a novel thrombin-activating protein that makes a significant contribution to the pathophysiological changes in platelet function associated with type 2 diabetes. Thus, strategies that target SMOC1 or its interaction with thrombin may be attractive therapeutic approaches to normalize platelet function in diabetes.

Long-term aerobic exercise training in type two diabetic patients alters the expression of miRNA-223 and its corresponding target, the P2RY12 receptor, attenuating platelet function

BACKGROUND

Type two diabetes mellitus (T2DM) patients are prone to develop atherothrombotic events due to platelet hyper-reactivity stemming from platelet miRNA-223 down-regulation and over-expression of its corresponding target, P2RY12.

OBJECTIVE

The study sought to determine the effects of long-term aerobic training on the expression levels of miRNA-223 and P2RY12 mRNA, and platelet function in T2DM patients.

METHODS

Twenty-four patients with T2DM (age, 60.0±2.8 yrs.) were selected and randomly divided into two groups: aerobic exercise training (AET, n = 12) and control (CON, n = 12). The AET protocol was performed with moderate intensity for 12 weeks, while patients in the CON group followed their usual routine. Weight, body mass index (BMI), peak oxygen consumption (VO2peak), lipid profile, fasting blood glucose (FBG), glycated hemoglobin (HbA1c), insulin resistance index (HOMA-IR), platelet miRNA-223 and P2RY12 expression were measured before and after the period.

RESULTS

There was a significant improvement in body weight, BMI, VO2peak, FBG, HbA1c, and HOMA-IR, after 12 weeks of AET (P <  0.01). Platelet aggregation decreased significantly after 12 weeks in the AET group compared with the CON (P <  0.001) group. Platelets' miRNA-223 and P2RY12 were significantly up- and down-regulated after AET in comparison with the CON group (P <  0.05), respectively. Moreover, the relative expression of miRNA-223 and P2RY12 significantly correlated with FBG changes following the intervention.

CONCLUSIONS

It can be concluded that long-term moderate-intensity aerobic training might be effective for reducing the occurrence of atherothrombotic events leading to premature death in T2DM patients through the modulation of miRNA-223, P2RY12 receptor expression, and platelet function.

Functional Role of miR-155 in the Pathogenesis of Diabetes Mellitus and Its Complications

Substantial evidence indicates that microRNA-155 (miR-155) plays a crucial role in the pathogenesis of diabetes mellitus (DM) and its complications. A number of clinical studies reported low serum levels of miR-155 in patients with type 2 diabetes (T2D). Preclinical studies revealed that miR-155 partakes in the phenotypic switch of cells within the islets of Langerhans under metabolic stress. Moreover, miR-155 was shown to regulate insulin sensitivity in liver, adipose tissue, and skeletal muscle. Dysregulation of miR-155 expression was also shown to predict the development of nephropathy, neuropathy, and retinopathy in DM. Here, we systematically describe the reports investigating the role of miR-155 in DM and its complications. We also discuss the recent results from in vivo and in vitro models of type 1 diabetes (T1D) and T2D, discussing the differences between clinical and preclinical studies and shedding light on the molecular pathways mediated by miR-155 in different tissues affected by DM.

The Landscape of Coding and Noncoding RNAs in Platelets

Significance: Levels of platelet noncoding RNAs (ncRNAs) are altered by disease, and ncRNAs may exert functions inside and outside of platelets. Their role in physiologic hemostasis and pathologic thrombosis remains to be explored. Recent Advances: The number of RNA classes identified in platelets has been growing since the past decade. Apart from coding messenger RNAs, the RNA landscape in platelets comprises ncRNAs such as microRNAs, circular RNAs, long ncRNAs, YRNAs, and potentially environmentally derived exogenous ncRNAs. Recent research has focused on the function of platelet RNAs beyond platelets, mediated through protective RNA shuttles or even cellular uptake of entire platelets. Multiple studies have also explored the potential of platelet RNAs as novel biomarkers. Critical Issues: Platelet preparations can contain contaminating leukocytes. Even few leukocytes may contribute a substantial amount of RNA. As biomarkers, platelet RNAs have shown associations with platelet activation, but it remains to be seen whether their measurements could improve diagnostics. It also needs to be clarified whether platelet RNAs influence processes beyond platelets. Future Directions: Technological advances such as single-cell RNA-sequencing might help to identify hyperreactive platelet subpopulations on a single-platelet level, avoid the common problem of leukocyte contamination in platelet preparations, and allow simultaneous profiling of native megakaryocytes and their platelet progeny to clarify to what extent the platelet RNA content reflects their megakaryocyte precursors or changes in the circulation. Antioxid. Redox Signal. 34, 1200-1216.

MicroRNA as Potential Biomarkers of Platelet Function on Antiplatelet Therapy: A Review

MicroRNAs (miRNAs) are small, non-coding RNAs, able to regulate cellular functions by specific gene modifications. Platelets are the major source for circulating miRNAs, with significant regulatory potential on cardiovascular pathophysiology. MiRNAs have been shown to modify the expression of platelet proteins influencing platelet reactivity. Circulating miRNAs can be determined from plasma, serum, or whole blood, and they can be used as diagnostic and prognostic biomarkers of platelet reactivity during antiplatelet therapy as well as novel therapeutic targets in cardiovascular diseases (CVDs). Herein, we review diagnostic and prognostic value of miRNAs levels related to platelet reactivity based on human studies, presenting its interindividual variability as well as the substantial role of genetics. Furthermore, we discuss antiplatelet treatment in the context of miRNAs alterations related to pathways associated with drug response.

Whole Blood miR-210, miR-122, miR-223 Expression Levels and Their Relationship With Iron Status Parameters and Hypercoagulability Indices in Children With Iron Deficiency Anemia

MicroRNAs have the potential to regulate systemic and cellular iron homeostasis at multiple points. In iron deficiency anemia (IDA), hypoxia, platelet reactivity, and potentially microRNAs play a role in the development of hypercoagulability. A total of 57 children diagnosed with IDA between October 2016 and October 2017 and 48 healthy children were included in this cross-sectional study. Blood count parameters, serum iron, transferrin saturation, ferritin level, maximum clot firmness (MCF), and clot formation time index, which are indicators of hypercoagulability in rotational thromboelastometry test, of the IDA and control groups obtained in our previous study were recorded. miR-210, miR-122, and miR-223 levels were analyzed. There was no difference in the miR-210, miR-122, and miR-223 levels between the IDA and control groups. Patients with hemoglobin (Hb) <8 g/dL had higher miR-210 levels than patients with Hb>8 g/dL (P<0.05). There was a negative correlation between miR-210 and Hb and ferritin levels, a positive correlation between miR-122 and ferritin levels, and a negative correlation between miR-223 and MCF index. In IDA, there is a close relationship between the severity of anemia and miR-210, and miR-210 expression is slightly increased in those with severe anemia. miR-210 and miR-122 collectively play a role in maintaining the iron balance. The correlation between miR-223, a platelet function regulator, and the MCF index, suggested that miR-223 has a role in the development of hypercoagulability in IDA.

miR-142-5p regulates the progression of diabetic retinopathy by targeting IGF1

As one of leading causes of blindness, diabetic retinopathy (DR) is a progressive microvascular complication of diabetes mellitus (DM). Despite significant efforts have been devoted to investigate DR over the years, the molecular mechanisms still remained unclear. Emerging evidences demonstrated that microRNAs (miRNAs) were tightly associated with pathophysiological development of DR. Hence, this study was aimed to illustrate the role and molecular mechanisms of miR-412-5p in progression of DR. Streptozotocin (STZ) treatment in rats and human retinal endothelial cell (HREC) models were used to simulate DR conditions in vivo and in vitro. Hematoxylin-eosin (HE) staining was used to demonstrate the morphology of retinal tissues of rats. Qualitative real-time polymerase chain reaction (qRT-PCR) detected miR-142-5p and vascular endothelial growth factor (VEGF) expression levels. Cell counting kit-8 (CCK8) assay and immunofluorescence (IF) measured the cell proliferation rates. Western blot tested the expression status of IGF1/IGF1R-mediated signaling pathway. Dual-luciferase reporter assays demonstrated the molecular mechanism of miR-142-5p. miR-142-5p level was down-regulated in retinal tissues of DR rats and high glucose (HG)-treated HRECs. Insulin-like growth factor 1 (IGF1) was identified as a direct target of miR-142-5p. The reduced miR-142-5p level enhanced HRECs proliferation via activating IGF/IGF1R-mediated signaling pathway including p-PI3K, p-ERK, p-AKT, and VEGF activation, ultimately giving rise to cell proliferation. Either miR-142-5p overexpression or IGF1 knockdown alleviated the pathological effects on retinal tissues in DR rats. Collectively, miR-142-5p participated in DR development by targeting IGF1/p-IGF1R signaling pathway and VEGF generation. This miR-142-5p/IGF1/VEGF axis provided a novel therapeutic target for DR clinical treatment.

Changes in neurodegeneration-related miRNAs in brains from CAPN1-/- mice

Calpain-1 knock-out (KO) mice exhibit enhanced susceptibility to neurodegeneration due to the lack of the neuroprotective function of calpain-1. Dicer has been shown to play a fundamental role in the biogenesis of most miRNAs. Here, we identified 45 differentially expressed miRNAs (DE miRNAs) in the brain of calpain-1 KO mice, as compared to wild-type mice. In particular, among all the DE miRNAs, 7 neurodegeneration-related miRNAs were found to be down-regulated in calpain-1 KO mice. We also found that Dicer is cleaved by calpain-1 in mouse brain, which generates an active fragment of Dicer with RNAse III activity and increases miRNA formation. Levels of active Dicer were reduced in brain homogenates from calpain-1 KO mice and incubation with calpain-1 and calcium restored Dicer activity and miRNA expression. Our results indicate that calpain-1 deletion results in decreased levels of active Dicer and changes in neurodegenerative-related miRNAs. These findings could account for some of the pathological changes found in brain of various mammals, including humans, with calpain-1 mutations or down-regulation.

Factor XIII and Fibrin Clot Properties in Acute Venous Thromboembolism

Coagulation factor XIII (FXIII) is converted by thrombin into its active form, FXIIIa, which crosslinks fibrin fibers, rendering clots more stable and resistant to degradation. FXIII affects fibrin clot structure and function leading to a more prothrombotic phenotype with denser networks, characterizing patients at risk of venous thromboembolism (VTE). Mechanisms regulating FXIII activation and its impact on fibrin structure in patients with acute VTE encompassing pulmonary embolism (PE) or deep vein thrombosis (DVT) are poorly elucidated. Reduced circulating FXIII levels in acute PE were reported over 20 years ago. Similar observations indicating decreased FXIII plasma activity and antigen levels have been made in acute PE and DVT with their subsequent increase after several weeks since the index event. Plasma fibrin clot proteome analysis confirms that clot-bound FXIII amounts associated with plasma FXIII activity are decreased in acute VTE. Reduced FXIII activity has been associated with impaired clot permeability and hypofibrinolysis in acute PE. The current review presents available studies on the role of FXIII in the modulation of fibrin clot properties during acute PE or DVT and following these events. Better understanding of FXIII’s involvement in the pathophysiology of acute VTE might help to improve current therapeutic strategies in patients with acute VTE.

Role, Laboratory Assessment and Clinical Relevance of Fibrin, Factor XIII and Endogenous Fibrinolysis in Arterial and Venous Thrombosis

Diseases such as myocardial infarction, ischaemic stroke, peripheral vascular disease and venous thromboembolism are major contributors to morbidity and mortality. Procoagulant, anticoagulant and fibrinolytic pathways are finely regulated in healthy individuals and dysregulated procoagulant, anticoagulant and fibrinolytic pathways lead to arterial and venous thrombosis. In this review article, we discuss the (patho)physiological role and laboratory assessment of fibrin, factor XIII and endogenous fibrinolysis, which are key players in the terminal phase of the coagulation cascade and fibrinolysis. Finally, we present the most up-to-date evidence for their involvement in various disease states and assessment of cardiovascular risk.

The multifaceted contribution of platelets in the emergence and aftermath of acute cardiovascular events

Atherosclerosis is an underlying cause of a broad array of cardiovascular diseases characterized by plaques, arterial wall thickening initiated by hyperlipidemia, pro-inflammatory signals, endothelial dysfunction and the influx of inflammatory cells. By still incompletely characterized mechanisms, these plaques can destabilize or erode, leading to thrombosis and blood vessel occlusion and becomes clinically manifest as angina pectoris, myocardial infarction (MI) or stroke. Among the several blood cell types that are involved in the development of atherosclerosis, the role of platelets during the thrombotic occlusion of ruptured or eroded plaques is well established and clinically exploited as evident by the extensive use of platelet inhibitors. However, there is increasing evidence that platelets are also involved in the earlier stages of atheroma development by exhibiting pro-inflammatory activities. The scope of this review is to describe the role of platelets in the initiation and propagation stages of atherosclerosis and beyond; in atherothrombotic complications.

Metformin regulates inflammation and fibrosis in diabetic kidney disease through TNC/TLR4/NF-κB/miR-155-5p inflammatory loop

BACKGROUND

Type 2 diabetes mellitus (T2DM) is significantly increasing worldwide, and the incidence of its complications is also on the rise. One of the main complications of T2DM is diabetic kidney disease (DKD). The glomerular filtration rate (GFR) and urinary albumin creatinine ratio (UACR) increase in the early stage. As the disease progresses, UACR continue to rise and GFR begins to decline until end-stage renal disease appears. At the same time, DKD will also increase the incidence and mortality of cardiovascular and cerebrovascular diseases. At present, the pathogenesis of DKD is not very clear. Therefore, exploration of the pathogenesis of DKD to find a treatment approach, so as to delay the development of DKD, is essential to improve the prognosis of DKD.

AIM

To detect the expression of tenascin-C (TNC) in the serum of T2DM patients, observe the content of TNC in the glomerulus of DKD rats, and detect the expression of TNC on inflammatory and fibrotic factors in rat mesangial cells (RMCs) cultured under high glucose condition, in order to explore the specific molecular mechanism of TNC in DKD and bring a new direction for the treatment of DKD.

METHODS

The expression level of TNC in the serum of diabetic patients was detected by enzyme-linked immunosorbent assay (ELISA), the protein expression level of TNC in the glomerular area of DKD rats was detected by immunohistochemistry, and the expression level of TNC in the rat serum was detected by ELISA. Rat glomerular mesangial cells were cultured. Following high glucose stimulation, the expression levels of related proteins and mRNA were detected by Western blot and polymerase chain reaction, respectively.

RESULTS

ELISA results revealed an increase in the serum TNC level in patients with T2DM. Increasing UACR and hypertension significantly increased the expression of TNC (P < 0.05). TNC expression was positively correlated with glycosylated haemoglobin (HbA1c) level, body mass index, systolic blood pressure, and UACR (P < 0.05). Immunohistochemical staining showed that TNC expression in the glomeruli of rats with streptozotocin-induced diabetes was significantly increased compared with normal controls (P < 0.05). Compared with normal rats, serum level of TNC in diabetic rats was significantly increased (P < 0.05), which was positively correlated with urea nitrogen and urinary creatinine (P < 0.05). The levels of TNC, Toll-like receptor-4 (TLR4), phosphorylated nuclear factor-κB p65 protein (Ser536) (p-NF-κB p65), and miR-155-5p were increased in RMCs treated with high glucose (P < 0.05). The level of TNC protein peaked 24 h after high glucose stimulation (P < 0.05). After TNC knockdown, the levels of TLR4, p-NF-κB p65, miR-155-5p, connective tissue growth factor (CTGF), and fibronectin (FN) were decreased, revealing that TNC regulated miR-155-5p expression through the TLR4/NF-κB p65 pathway, thereby regulating inflammation (NF-κB p65) and fibrosis (CTGF and FN) in individuals with DKD. In addition, metformin treatment may relive the processes of inflammation and fibrosis in individuals with DKD by reducing the levels of the TNC, p-NF-κB p65, CTGF, and FN proteins.

CONCLUSION

TNC can promote the occurrence and development of DKD. Interfering with the TNC/TLR4/NF-κB p65/miR-155-5p pathway may become a new target for DKD treatment.

The Role of Epigenetics in the Regulation of Hemostatic Balance

Epigenetics, a term conventionally used to explain the intricate interplay between genes and the environment, is now regarded as the fundament of developmental biology. Several lines of evidence garnered over the past decades suggest that epigenetic alterations, mostly encompassing DNA methylation, histone tail modifications, and generation of microRNAs, play an important, though still incompletely explored, role in both primary and secondary hemostasis. Epigenetic variations may interplay with platelet functions and their responsiveness to antiplatelet drugs, and they may also exert a substantial contribution in modulating the production and release into the bloodstream of proteins involved in blood coagulation and fibrinolysis. This emerging evidence may have substantial biological and clinical implications. An enhanced understanding of posttranscriptional mechanisms would help to clarify some remaining enigmatic issues in primary and secondary hemostasis, which cannot be thoughtfully explained by genetics or biochemistry alone. Increased understanding would also pave the way to developing innovative tests for better assessment of individual risk of bleeding or thrombosis. The accurate recognition of key epigenetic mechanisms in hemostasis would then contribute to identify new putative therapeutic targets, and develop innovative agents that could be helpful for preventing or managing a vast array of hemostasis disturbances.

Platelet-derived calpain cleaves the endothelial protease-activated receptor 1 to induce vascular inflammation in diabetes

Diabetes mellitus is a major risk factor for cardiovascular disease. Platelets from diabetic patients are hyperreactive and release microparticles that carry activated cysteine proteases or calpains. Whether platelet-derived calpains contribute to the development of vascular complications in diabetes is unknown. Here we report that platelet-derived calpain1 (CAPN1) cleaves the protease-activated receptor 1 (PAR-1) on the surface of endothelial cells, which then initiates a signaling cascade that includes the activation of the tumor necrosis factor (TNF)-α converting enzyme (TACE). The latter elicits the shedding of the endothelial protein C receptor and the generation of TNF-α, which in turn, induces intracellular adhesion molecule (ICAM)-1 expression to promote monocyte adhesion. All of the effects of CAPN1 were mimicked by platelet-derived microparticles from diabetic patients or from wild-type mice but not from CAPN1^−/− mice, and were not observed in PAR-1-deficient endothelial cells. Importantly, aortae from diabetic mice expressed less PAR-1 but more ICAM-1 than non-diabetic mice, effects that were prevented by treating diabetic mice with a calpain inhibitor as well as by the platelet specific deletion of CAPN1. Thus, platelet-derived CAPN1 contributes to the initiation of the sterile vascular inflammation associated with diabetes via the cleavage of PAR-1 and the release of TNF-α from the endothelial cell surface.

MicroRNAs in Platelets: Should I Stay or Should I Go?

In this chapter, we discuss different topics always using the microRNA as the guiding thread of the review. MicroRNAs, member of small noncoding RNAs family, are an important element involved in gene expression. We cover different issues such as their importance in the differentiation and maturation of megakaryocytes (megakaryopoiesis), as well as the role in platelets formation (thrombopoiesis) focusing on the described relationship between miRNA and critical myeloid lineage transcription factors such as RUNX1, chemokines receptors as CRCX4, or central hormones in platelet homeostasis like TPO, as well as its receptor (MPL) and the TPO signal transduction pathway, that is JAK/STAT. In addition to platelet biogenesis, we review the microRNA participation in platelets physiology and function. This review also introduces the use of miRNAs as biomarkers of platelet function since the detection of pathogenic situations or response to therapy using these noncoding RNAs is getting increasing interest in disease management. Finally, this chapter describes the participation of platelets in cellular interplay, since extracellular vesicles have been demonstrated to have the ability to deliver microRNAs to others cells, modulating their function through intercellular communication, redefining the extracellular vesicles from the so-called “platelet dust” to become mediators of intercellular communication.

Repurposing anti-inflammasome NRTIs for improving insulin sensitivity and reducing type 2 diabetes development

Innate immune signaling through the NLRP3 inflammasome is activated by multiple diabetes-related stressors, but whether targeting the inflammasome is beneficial for diabetes is still unclear. Nucleoside reverse-transcriptase inhibitors (NRTI), drugs approved to treat HIV-1 and hepatitis B infections, also block inflammasome activation. Here, we show, by analyzing five health insurance databases, that the adjusted risk of incident diabetes is 33% lower in patients with NRTI exposure among 128,861 patients with HIV-1 or hepatitis B (adjusted hazard ratio for NRTI exposure, 0.673; 95% confidence interval, 0.638 to 0.710; P < 0.0001; 95% prediction interval, 0.618 to 0.734). Meanwhile, an NRTI, lamivudine, improves insulin sensitivity and reduces inflammasome activation in diabetic and insulin resistance-induced human cells, as well as in mice fed with high-fat chow; mechanistically, inflammasome-activating short interspersed nuclear element (SINE) transcripts are elevated, whereas SINE-catabolizing DICER1 is reduced, in diabetic cells and mice. These data suggest the possibility of repurposing an approved class of drugs for prevention of diabetes.

Reduced Platelet miR-223 Induction in Kawasaki Disease Leads to Severe Coronary Artery Pathology Through a miR-223/PDGFRβ Vascular Smooth Muscle Cell Axis

RATIONALE

Kawasaki disease (KD) is an acute vasculitis of early childhood that can result in permanent coronary artery structural damage. The cause for this arterial vulnerability in up to 15% of patients with KD is unknown. Vascular smooth muscle cell dedifferentiation play a key role in the pathophysiology of medial damage and aneurysm formation, recognized arterial pathology in KD. Platelet hyperreactivity is also a hallmark of KD. We recently demonstrated that uptake of platelets and platelet-derived miRNAs influences vascular smooth muscle cell phenotype in vivo.

OBJECTIVE

We set out to explore whether platelet/vascular smooth muscle cell (VSMC) interactions contribute to coronary pathology in KD.

METHODS AND RESULTS

We prospectively recruited and studied 242 patients with KD, 75 of whom had documented coronary artery pathology. Genome-wide miRNA sequencing and droplet digital PCR demonstrated that patient with KD platelets have significant induction of miR-223 compared with healthy controls (HCs). Platelet-derived miR-223 has recently been shown to promote vascular smooth muscle quiescence and resolution of wound healing after vessel injury. Paradoxically, patients with KD with the most severe coronary pathology (giant coronary artery aneurysms) exhibited a lack of miR-223 induction. Hyperactive platelets isolated from patients with KD are readily taken up by VSMCs, delivering functional miR-223 into the VSMCs promoting VSMC differentiation via downregulation of PDGFRβ (platelet-derived growth factor receptor β). The lack of miR-223 induction in patients with severe coronary pathology leads to persistent VSMC dedifferentiation. In a mouse model of KD (Lactobacillus casei cell wall extract injection), miR-223 knockout mice exhibited increased medial thickening, loss of contractile VSMCs in the media, and fragmentation of medial elastic fibers compared with WT mice, which demonstrated significant miR-223 induction upon Lactobacillus casei cell wall extract challenge. The excessive arterial damage in the miR-223 knockout could be rescued by adoptive transfer of platelet, administration of miR-223 mimics, or the PDGFRβ inhibitor imatinib mesylate. Interestingly, miR-223 levels progressively increase with age, with the lowest levels found in <5-year-old. This provides a basis for coronary pathology susceptibility in this very young cohort.

CONCLUSIONS

Platelet-derived miR-223 (through PDGFRβ inhibition) promotes VSMC differentiation and resolution of KD induced vascular injury. Lack of miR-223 induction leads to severe coronary pathology characterized by VSMC dedifferentiation and medial damage. Detection of platelet-derived miR-223 in patients with KD (at the time of diagnosis) may identify patients at greatest risk of coronary artery pathology. Moreover, targeting platelet miR-223 or VSMC PDGFRβ represents potential therapeutic strategies to alleviate coronary pathology in KD. Graphic Abstract: A graphic abstract is available for this article.

Revisiting Platelets and Toll-Like Receptors (TLRs): At the Interface of Vascular Immunity and Thrombosis

While platelet function has traditionally been described in the context of maintaining vascular integrity, recent evidence suggests that platelets can modulate inflammation in a much more sophisticated and nuanced manner than previously thought. Some aspects of this expanded repertoire of platelet function are mediated via expression of Toll-like receptors (TLRs). TLRs are a family of pattern recognition receptors that recognize pathogen-associated and damage-associated molecular patterns. Activation of these receptors is crucial for orchestrating and sustaining the inflammatory response to both types of danger signals. The TLR family consists of 10 known receptors, and there is at least some evidence that each of these are expressed on or within human platelets. This review presents the literature on TLR-mediated platelet activation for each of these receptors, and the existing understanding of platelet-TLR immune modulation. This review also highlights unresolved methodological issues that potentially contribute to some of the discrepancies within the literature, and we also suggest several recommendations to overcome these issues. Current understanding of TLR-mediated platelet responses in influenza, sepsis, transfusion-related injury and cardiovascular disease are discussed, and key outstanding research questions are highlighted. In summary, we provide a resource—a “researcher’s toolkit”—for undertaking further research in the field of platelet-TLR biology.

High-efficiency unassisted transfection of platelets with naked double-stranded miRNAs modulates signal-activated translation and platelet function

We sought novel approaches to improve transfection efficiencies of microRNAs (miRNAs) in platelets, and to apply these approaches to investigate the roles of miRNAs in regulating signal-activated protein translation and functional effects. We found that ex vivo human platelets support gymnosis---internalization of ectopic miRNAs following co-incubation in the absence of conventional transfection reagents or schemes---and subsequently incorporate transfected miRNA into ARGONAUTE2 (AGO2)-based RNA-induced silencing complexes (RISC). Thrombin/fibrinogen stimulation activated translation of miR-223-3p target SEPTIN2, which was suppressed by miR-223-3p transfection in an AGO2/RISC-dependent manner. Thrombin/fibrinogen-induced exosome and microvesicle generation was inhibited by miR-223-3p transfection, and this effect was reversed with a RISC inhibitor. Platelet gymnosis of naked miRNAs appeared to be mediated in part by endocytic pathways including clathrin-dependent and fluid-phase endocytosis and caveolae. These results demonstrate the ability of ex vivo platelets to internalize ectopic miRNAs by unassisted transfection, and utilize them to modulate signal-activated translation and platelet function. Our results identify new roles for miR-223-3p in extracellular vesicle generation in stimulated platelets. High-efficiency gymnotic transfection of miRNAs in ex vivo platelets may be a broadly useful tool for exploring molecular genetic regulation of platelet function.

Brain Dicer1 Is Down-Regulated in a Mouse Model of Alzheimer's Disease Via Aβ42-Induced Repression of Nuclear Factor Erythroid 2-Related Factor 2

Dicer1 is a microRNA-processing enzyme which plays critical roles in neuronal survival and neuritogenesis. Dicer1 deletion induces neurodegeneration or degeneration in retinal pigment epithelium, which is associated with oxidative stress. Oxidative stress is thought to be central in the pathogenesis of Alzheimer's disease (AD). Therefore, we hypothesize that Dicer1 may play roles in AD. Using immunoblotting and quantitative real-time PCR, Dicer1 protein and mRNA were reduced in the hippocampi of the AD mouse model APPswe/PSEN1dE9 compared with littermate controls. SiRNA-mediated Dicer1 knockdown induced oxidative stress and apoptosis and reduced mitochondrial membrane potential in cultured neurons. Chronic Aβ42 exposure decreased Dicer1 and nuclear factor erythroid 2-related factor 2 (Nrf2) which were reversed by N-acetyl-cystein. Nrf2 overexpression increased Dicer1 mRNA and protein and reverted the Aβ42-induced Dicer1 reduction. We further cloned Dicer1 promoter variants harboring the Nrf2-binding site, the antioxidant response elements (ARE), into a luciferase reporter and found that simultaneous transfection of Nrf2-expressing plasmid increased luciferase expression from these promoter constructs. ChIP assays indicated that Nrf2 directly interacted with the ARE motifs in the Dicer1 promoter. Furthermore, Dicer1 overexpression in cultured neurons reverted Aβ42-induced neurite deficits. Notably, injection of Dicer1-expressing adenovirus into the hippocampus of the mice significantly improved spatial learning. Altogether, we found novel roles of Dicer1 in AD and a novel regulatory pathway for Dicer1. These results suggest that Dicer1 is a target in AD therapy, especially at the early stage of this disorder. In this study, we found that Dicer1 was reduced in the brain of AD mice which is the first report to examine Dicer1 in AD. We further found (i) that Aβ42 exposure decreased Dicer1 via attenuating Nrf2-ARE signaling and (ii) injection of Dicer1-expressing adenovirus into the hippocampus of the AD mice significantly improved spatial learning. Altogether, we found novel roles of Dicer1 in AD and a novel regulatory pathway for Dicer1. This study may open new avenues for investigating potential pathognomonics and pathogenesis in AD.

Restoring the Platelet miR-223 by Calpain Inhibition Alleviates the Neointimal Hyperplasia in Diabetes

Platelet hyperactivity is the hallmark of diabetes, and platelet activation plays a crucial role in diabetic vascular complications. Recent studies have shown that upon activation, platelet-derived miRNAs are incorporated into vascular smooth muscle cells (VSMCs), regulating the phenotypic switch of VSMC. Under diabetes, miRNA deficiency in platelets fails to regulate the VSMC phenotypic switch. Therefore, manipulation of platelet-derived miRNAs expression may provide therapeutic option for diabetic vascular complications. We seek to investigate the effect of calpeptin (calpain inhibitor) on the expression of miRNAs in diabetic platelets, and elucidate the downstream signaling pathway involved in protecting from neointimal formation in diabetic mice with femoral wire injury model. Using human cell and platelet coculture, we demonstrate that diabetic platelet deficient of miR-223 fails to suppress VSMC proliferation, while overexpression of miR-223 in diabetic platelets suppressed the proliferation of VSMC to protect intimal hyperplasia. Mechanistically, miR-223 directly targets the insulin-like growth factor-1 receptor (IGF-1R), which inhibits the phosphorylation of GSK3β and activates the phosphorylation of AMPK, resulting in reduced VSMC dedifferentiation and proliferation. Using a murine model of vascular injury, we show that calpeptin restores the platelet expression of miR-223 in diabetes, and the horizontal transfer of platelet miR-223 into VSMCs inhibits VSMC proliferation in the injured artery by targeting the expression of IGF-1R. Our data present that the platelet-derived miR-223 suppressed VSMC proliferation via the regulation miR-223/IGF-1R/AMPK signaling pathways, and inhibition of calpain alleviates neointimal formation by restoring the expression of miR-223 in diabetic platelet.

MicroRNA-21/PDCD4 Proapoptotic Signaling From Circulating CD34+ Cells to Vascular Endothelial Cells: A Potential Contributor to Adverse Cardiovascular Outcomes in Patients With Critical Limb Ischemia

OBJECTIVE

In patients with type 2 diabetes (T2D) and critical limb ischemia (CLI), migration of circulating CD34⁺ cells predicted cardiovascular mortality at 18 months after revascularization. This study aimed to provide long-term validation and mechanistic understanding of the biomarker.

RESEARCH DESIGN AND METHODS

The association between CD34⁺ cell migration and cardiovascular mortality was reassessed at 6 years after revascularization. In a new series of T2D-CLI and control subjects, immuno-sorted bone marrow CD34⁺ cells were profiled for miRNA expression and assessed for apoptosis and angiogenesis activity. The differentially regulated miRNA-21 and its proapoptotic target, PDCD4, were titrated to verify their contribution in transferring damaging signals from CD34⁺ cells to endothelial cells.

RESULTS

Multivariable regression analysis confirmed that CD34⁺ cell migration forecasts long-term cardiovascular mortality. CD34⁺ cells from T2D-CLI patients were more apoptotic and less proangiogenic than those from control subjects and featured miRNA-21 downregulation, modulation of several long noncoding RNAs acting as miRNA-21 sponges, and upregulation of the miRNA-21 proapoptotic target PDCD4. Silencing miR-21 in control CD34⁺ cells phenocopied the T2D-CLI cell behavior. In coculture, T2D-CLI CD34⁺ cells imprinted naive endothelial cells, increasing apoptosis, reducing network formation, and modulating the TUG1 sponge/miRNA-21/PDCD4 axis. Silencing PDCD4 or scavenging reactive oxygen species protected endothelial cells from the negative influence of T2D-CLI CD34⁺ cells.

CONCLUSIONS

Migration of CD34⁺ cells predicts long-term cardiovascular mortality in T2D-CLI patients. An altered paracrine signaling conveys antiangiogenic and proapoptotic features from CD34⁺ cells to the endothelium. This damaging interaction may increase the risk for life-threatening complications.

microRNAs as promising biomarkers of platelet activity in antiplatelet therapy monitoring

Given the high morbidity and mortality of cardiovascular diseases (CVDs), novel biomarkers for platelet reactivity are urgently needed. Ischemic events in CVDs are causally linked to platelets, small anucleate cells important for hemostasis. The major side-effect of antiplatelet therapy are life-threatening bleeding events. Current platelet function tests are not sufficient in guiding treatment decisions. Platelets host a broad spectrum of microRNAs (miRNAs) and are a major source of cell-free miRNAs in the blood stream. Platelet-related miRNAs have been suggested as biomarkers of platelet activation and assessment of antiplatelet therapy responsiveness. Platelets release miRNAs upon activation, possibly leading to alterations of plasma miRNA levels in conjunction with CVD or inadequate platelet inhibition. Unlike current platelet function tests, which measure platelet activation ex vivo, signatures of platelet-related miRNAs potentially enable the assessment of in vivo platelet reactivity. Evidence suggests that some miRNAs are responsive to platelet inhibition, making them promising biomarker candidates. In this review, we explain the secretion of miRNAs upon platelet activation and discuss the potential use of platelet-related miRNAs as biomarkers for CVD and antiplatelet therapy monitoring, but also highlight remaining gaps in our knowledge and uncertainties regarding clinical utility. We also elaborate on technical issues and limitations concerning plasma miRNA quantification.

Dicer up-regulation by inhibition of specific proteolysis in differentiating monocytic cells

Dicer is a ribonuclease III enzyme in biosynthesis of miRNAs, regulators of gene expression involved in macrophage differentiation. We found a specific truncation of Dicer in monocytic cells resulting from apparently constitutive cleavage by a serine protease. Inhibition of this proteolytic truncation, which occurred during macrophage differentiation in presence of TLR ligands or prostaglandin E₂, up-regulates full-length Dicer and promotes miR biosynthesis. Regulation of transcription of pri-miRNA is one mode to regulate biosynthesis of mature miRNA. Inhibition of constitutive proteolysis of Dicer, as described here, provides a second layer of regulation, at the level of miRNA processing. Our data provide insights to Dicer and miRNAs in macrophage polarization/differentiation, a key process in the innate immune response.

Dicer is a ribonuclease III enzyme in biosynthesis of micro-RNAs (miRNAs). Here we describe a regulation of Dicer expression in monocytic cells, based on proteolysis. In undifferentiated Mono Mac 6 (MM6) cells, full-length Dicer was undetectable; only an ∼50-kDa fragment appeared in Western blots. However, when MM6 cells were treated with zymosan or LPS during differentiation with TGF-β and 1,25diOHvitD3, full-length Dicer became abundant together with varying amounts of ∼170- and ∼50-kDa Dicer fragments. Mass spectrometry identified the Dicer fragments and showed cleavage about 450 residues upstream from the C terminus. Also, PGE₂ (prostaglandin E2) added to differentiating MM6 cells up-regulated full-length Dicer, through EP2/EP4 and cAMP. The TLR stimuli strongly induced miR-146a-5p, while PGE₂ increased miR-99a-5p and miR-125a-5p, both implicated in down-regulation of TNFα. The Ser protease inhibitor AEBSF (4-[2-aminoethyl] benzene sulfonyl fluoride) up-regulated full-length Dicer, both in MM6 cells and in primary human blood monocytes, indicating a specific proteolytic degradation. However, AEBSF alone did not lead to a general increase in miR expression, indicating that additional mechanisms are required to increase miRNA biosynthesis. Finally, differentiation of monocytes to macrophages with M-CSF or GM-CSF strongly up-regulated full-length Dicer. Our results suggest that differentiation regimens, both in the MM6 cell line and of peripheral blood monocytes, inhibit an apparently constitutive Dicer proteolysis, allowing for increased formation of miRNAs.

Reduced miR-26b Expression in Megakaryocytes and Platelets Contributes to Elevated Level of Platelet Activation Status in Sepsis

In sepsis, platelets may become activated via toll-like receptors (TLRs), causing microvascular thrombosis. Megakaryocytes (MKs) also express these receptors; thus, severe infection may modulate thrombopoiesis. To explore the relevance of altered miRNAs in platelet activation upon sepsis, we first investigated sepsis-induced miRNA expression in platelets of septic patients. The effect of abnormal Dicer level on miRNA expression was also evaluated. miRNAs were profiled in septic vs. normal platelets using TaqMan Open Array. We validated platelet miR-26b with its target SELP (P-selectin) mRNA levels and correlated them with clinical outcomes. The impact of sepsis on MK transcriptome was analyzed in MEG-01 cells after lipopolysaccharide (LPS) treatment by RNA-seq. Sepsis-reduced miR-26b was further studied using Dicer1 siRNA and calpain inhibition in MEG-01 cells. Out of 390 platelet miRNAs detected, there were 121 significantly decreased, and 61 upregulated in sepsis vs. controls. Septic platelets showed attenuated miR-26b, which were associated with disease severity and mortality. SELP mRNA level was elevated in sepsis, especially in platelets with increased mean platelet volume, causing higher P-selectin expression. Downregulation of Dicer1 generated lower miR-26b with higher SELP mRNA, while calpeptin restored miR-26b in MEG-01 cells. In conclusion, decreased miR-26b in MKs and platelets contributes to an increased level of platelet activation status in sepsis.

Function of Dicer with regard to Energy Homeostasis Regulation, Structural Modification, and Cellular Distribution

As a type III ribonuclease (RNase III) specifically cleaving double-stranded RNA substrates into short fragments, Dicer is indispensable in a range of physi/pathologic processes, e.g., nutrient deprivation, hypoxia, or DNA damage. Therefore, much interest has been paid to the research of this protein as well as its products like microRNAs (miRNAs). The close relationship between Dicer levels and fluctuations of nutrient availability suggests that the protein participates in the regulation of systemic energy homeostasis. Through miRNAs, Dicer regulates the hypothalamic melanocortin-4 system and central autophagy promoting energy expenditure. Moreover, by influencing canonical energy sensors like adenosine monophosphate-activated protein kinase (AMPK) or mammalian target of rapamycin (mTOR), Dicer favors catabolism in the periphery. Taken together, Dicer might be targeted in the control of energy dysregulation. However, factors affecting its RNase activity should be noted. Firstly, modulation of structural integrity affects its role as a ribonuclease. Secondly, although previously known as a cytosolic endoribonuclease, evidence suggests Dicer can relocalize into the nucleus where it could also produce small RNAs. In this review, we probe into involvement of Dicer in energy homeostasis as well as its structural integrity or cellular distribution which affects its ability to produce miRNAs, in the hope of providing novel insights into its mechanism of action for future application.

Hypertension Associated With Hyperlipidemia Induced Different MicroRNA Expression Profiles in Plasma, Platelets, and Platelet-Derived Microvesicles; Effects of Endothelial Progenitor Cell Therapy

Aim: The aim of this study was to analyze the expressed profiles of miRNAs in plasma, platelets, and platelet-derived microvesicles (PMVs) obtained from experimental induced atherosclerosis animal model and to investigate the effect of EPC transplantation on these profiles. Methods: Seventeen selected circulating miRNAs (miR-19a,-21,-126,-146a,-223,-26b,-92a,-222,-210,-221,-143,-10a,-145,-155,-34a,-204, and miR-214) were individually analyzed in plasma, platelets, and PMVs isolated from peripheral blood of hypertensive-hyperlipidemic hamsters treated or not with endothelial progenitor cells (EPCs), and of healthy hamsters taken as control group. Results: Comparative with control group, in hypertension associated with hyperlipidemia the investigated miRNA expression profiles were different: (i) in plasma, the levels of all investigated miRNAs were significantly increased, the highest enhances being noticed for miR-21,-146a,-221,-143,-34a, and miR-204; (ii) in platelets, the expressions of almost all miRNAs were significantly elevated, remarkable for miR-126,-146a,-223,-222, and miR-214, while levels of miR-143, miR-10a, and miR-145 were significantly reduced; (iii) in PMVs, numerous miRNAs were found to have significantly increased levels, especially miR-222,-221,-210, and miR-34a, whereas expressions of various miRNAs as miR-223,-214,-146a,-143,-10a, and miR-145 were significantly decreased. The treatment with EPCs had the following reverse effects: (i) in plasma, significantly reduced the expression of miR-26b,-143,-34a,-204, and miR-214; (ii) in platelets, significantly decreased the levels of almost investigated miRNAs, with remarkably diminishing for miR-126 and miR-221; and (iii) in PMVs, significantly lowered the expression of some miRNAs, with considerably reductions for miR-222,-221,-210, and miR-19a, while the level of miR-214 was found elevated. Conclusions: The present study revealed that miRNAs have differential expression profiles in plasma, platelets, and PMVs under hypertension associated with hyperlipidemia conditions. The different miRNA profile in PMVs compared with platelets indicated an active mechanism of selective packing of miRNAs into PMVs from maternal cells; various miRNAs such as miR-19a,-21,-126,-26b,-92a,-155,-204,-210,-221,-222, and-34a delivered by PMVs may contribute to enrichment of circulating plasma miRNA expression. In addition, our study showed that the EPC-based therapy can regulate the expressions of investigated miRNAs into the three sources. These results provide novel information that could help in finding potential targets for the development of new therapeutic strategies in the cardiovascular disease.

Gene polymorphism and plasma levels of miR-155 in diabetic retinopathy

Circulating microRNA-155 (miR-155) is associated with type 2 diabetes mellitus (T2DM) and the rs767649 polymorphism in the pre-MIR155 gene is associated with miR-155 expression. However, their relationship with diabetic retinopathy (DR) is still unknown. Therefore, the aim of this case-control study was to test the hypothesis that the rs767649 polymorphism in the pre-MIR155 gene is associated with DR in South Brazilians with T2DM. We also evaluated the association of plasma levels of miR-155 with DR and the rs767649 polymorphism in a subgroup of subjects. The rs767649 polymorphism was genotyped in 139 blood donors and 546 T2DM patients (244 had no DR, 161 had non-proliferative DR and 141 had proliferative DR). miR-155 expression was quantified in 20 blood donors and 60 T2DM patients (20 from each group). Among T2DM patients, the carriership of the A allele and the A allele were more frequent in subjects with DR than in those without it (P < 0.05), and the A allele was independently associated with an increased risk of DR (adjusted OR = 2.12, 95% CI = 1.12-4.01). The plasma levels of miR-155 were lower in T2DM patients than in blood donors (P < 0.001). However, the miR-155 levels did not differ according to the presence and severity of DR or according to rs767649 genotypes among T2DM patients. These findings support that the rs767649 polymorphism in the pre-MIR155 gene is associated with DR in T2DM and that the miR-155 plasma levels might be associated with T2DM. Additional studies are needed to further investigate their clinical significance in DR and T2DM.

Double-Stranded RNA Is a Novel Molecular Target in Osteomyelitis Pathogenesis: A Translational Avian Model for Human Bacterial Chondronecrosis with Osteomyelitis

Osteomyelitis remains a serious inflammatory bone disease that affects millions of individuals worldwide and for which there is no effective treatment. Despite scientific evidence that Staphylococcus bacteria are the most common causative species for human bacterial chondronecrosis with osteomyelitis (BCO), much remains to be understood about the underlying virulence mechanisms. Herein, we show increased levels of double-stranded RNA (dsRNA) in infected bone in a Staphylococcus-induced chicken BCO model and in human osteomyelitis samples. Administration of synthetic [poly(I:C)] or genetic (Alu) dsRNA induces human osteoblast cell death. Similarly, infection with Staphylococcus isolated from chicken BCO induces dsRNA accumulation and cell death in human osteoblast cell cultures. Both dsRNA administration and Staphylococcus infection activate NACHT, LRR and PYD domains-containing protein (NLRP)3 inflammasome and increase IL18 and IL1B gene expression in human osteoblasts. Pharmacologic inhibition with Ac-YVAD-cmk of caspase 1, a critical component of the NLRP3 inflammasome, prevents DICER1 dysregulation- and dsRNA-induced osteoblast cell death. NLRP3 inflammasome and its components are also activated in bone from BCO chickens and humans with osteomyelitis, compared with their healthy counterparts. These findings provide a rationale for the use of chicken BCO as a human-relevant spontaneous animal model for osteomyelitis and identify dsRNA as a new treatment target for this debilitating bone pathogenesis.

Cold storage conditions modify microRNA expressions for platelet transfusion

MicroRNAs (miRNAs) are small RNA molecules that modulate gene and protein expression in hematopoiesis. Platelets are known to contain a fully functional miRNA machinery. While platelets used for transfusion are normally stored at room temperature, recent evidence suggests more favorable effects under a cold-storage condition, including higher adhesion and aggregation properties. Thus, we sought to determine whether functional differences in platelets are associated with the differential profiling of platelet miRNA expressions. To obtain the miRNA expression profile, next-generation sequencing was performed on human platelets obtained from 10 healthy subjects. The miRNAs were quantified after being stored in three different conditions: 1) baseline (before storage), 2) stored at 22°C with agitation for 72 h, and 3) stored at 4°C for 72 h. Following the identification of miRNAs by sequencing, the results were validated at the level of mature miRNAs from 18 healthy subjects, by using quantitative polymerase chain reaction (qPCR). Differential expression was observed for 125 miRNAs that were stored at 4°C and 9 miRNAs stored at 22°C as compared to the baseline. The validation study by qPCR confirmed that storage at 4°C increased the expression levels (fold change 95% CI) of mir-20a-5p (1.87, p<0.0001), mir-10a-3p (1.88, p<0.0001), mir-16-2-3p (1.54, p<0.01), and mir-223-5p (1.38, p<0.05), compared with those of the samples stored at 22°C. These results show that miRNAs correlate with platelet quality under specific storage conditions. The data indicate that miRNAs could be potentially used as biomarkers of platelet quality.

Redox Regulation of Calpains: Consequences on Vascular Function

SIGNIFICANCE

Calpains (CAPNs) are a family of calcium-activated cysteine proteases. The ubiquitous isoforms CAPN1 and CAPN2 have been involved in the maintenance of vascular integrity, but uncontrolled CAPN activation plays a role in the pathogenesis of vascular diseases. Recent Advances: It is well accepted that chronic and acute overproduction of reactive oxygen species (ROS) is associated with the development of vascular diseases. There is increasing evidence that ROS can also affect the CAPN activity, suggesting CAPN as a potential link between oxidative stress and vascular disease.

CRITICAL ISSUES

The physiopathological relevance of ROS in regulating the CAPN activity is not fully understood but seems to involve direct effects on CAPNs, redox modifications of CAPN substrates, as well as indirect effect on CAPNs via changes in Ca²⁺ levels. Finally, CAPNs can also stimulate ROS production; however, data showing in which context ROS are the causes or the consequences of CAPN activation are missing.

FUTURE DIRECTIONS

Detailed characterization of the molecular mechanisms underlying the regulation of the different members of the CAPN system by specific ROS would help understanding the pathophysiological role of CAPN in the modulation of the vascular function. Moreover, given that CAPNs have been found in different cellular compartments such as mitochondria and nucleus as well as in the extracellular space, identification of new CAPN targets as well as their functional consequences would add new insights in the function of these enigmatic proteases.

Platelet-derived miR-223 promotes a phenotypic switch in arterial injury repair

Upon arterial injury, endothelial denudation leads to platelet activation and delivery of multiple agents (e.g., TXA2, PDGF), promoting VSMC dedifferentiation and proliferation (intimal hyperplasia) during injury repair. The process of resolution of vessel injury repair, and prevention of excessive repair (switching VSMCs back to a differentiated quiescent state), is poorly understood. We now report that internalization of APs by VSMCs promotes resolution of arterial injury by switching on VSMC quiescence. Ex vivo and in vivo studies using lineage tracing reporter mice (PF4-cre × mT/mG) demonstrated uptake of GFP-labeled platelets (mG) by mTomato red-labeled VSMCs (mT) upon arterial wire injury. Genome-wide miRNA sequencing of VSMCs cocultured with APs identified significant increases in platelet-derived miR-223. miR-223 appears to directly target PDGFRβ (in VSMCs), reversing the injury-induced dedifferentiation. Upon arterial injury, platelet miR-223-KO mice exhibited increased intimal hyperplasia, whereas miR-223 mimics reduced intimal hyperplasia. Diabetic mice with reduced expression of miR-223 exhibited enhanced VSMC dedifferentiation and proliferation and increased intimal hyperplasia. Our results suggest that horizontal transfer of platelet-derived miRNAs into VSMCs provides a novel mechanism for regulating VSMC phenotypic switching. Platelets thus play a dual role in vascular injury repair, initiating an immediate repair process and, concurrently, a delayed process to prevent excessive repair.