Effect of sarpogrelate hydrochloride on platelet-derived microparticles and various soluble adhesion molecules in diabetes mellitus

Biomarkers of aging in frailty and age-associated disorders: State of the art and future perspective

According to the Geroscience concept that organismal aging and age-associated diseases share the same basic molecular mechanisms, the identification of biomarkers of age that can efficiently classify people as biologically older (or younger) than their chronological (i.e. calendar) age is becoming of paramount importance. These people will be in fact at higher (or lower) risk for many different age-associated diseases, including cardiovascular diseases, neurodegeneration, cancer, etc. In turn, patients suffering from these diseases are biologically older than healthy age-matched individuals. Many biomarkers that correlate with age have been described so far. The aim of the present review is to discuss the usefulness of some of these biomarkers (especially soluble, circulating ones) in order to identify frail patients, possibly before the appearance of clinical symptoms, as well as patients at risk for age-associated diseases. An overview of selected biomarkers will be discussed in this regard, in particular we will focus on biomarkers related to metabolic stress response, inflammation, and cell death (in particular in neurodegeneration), all phenomena connected to inflammaging (chronic, low-grade, age-associated inflammation). In the second part of the review, next-generation markers such as extracellular vesicles and their cargos, epigenetic markers and gut microbiota composition, will be discussed. Since recent progresses in omics techniques have allowed an exponential increase in the production of laboratory data also in the field of biomarkers of age, making it difficult to extract biological meaning from the huge mass of available data, Artificial Intelligence (AI) approaches will be discussed as an increasingly important strategy for extracting knowledge from raw data and providing practitioners with actionable information to treat patients.

Microvesicle-associated and circulating microRNAs in diabetic dyslipidemia: miR-218, miR-132, miR-143, and miR-21, miR-122, miR-155 have biomarker potential

BACKGROUND

Circulating MicroRNAs (miRNAs) carried by microvesicles (MVs) have various physiological and pathological functions by post-transcriptional regulation of gene expression being considered markers for many diseases including diabetes and dyslipidemia. We aimed to identify new common miRNAs both in MVs and plasma that could be predictive biomarkers for diabetic dyslipidemia evolution.

METHODS

For this purpose, plasma from 63 participants in the study (17 type 2 diabetic patients, 17 patients with type 2 diabetes and dyslipidemia, 14 patients with dyslipidemia alone and 15 clinically healthy persons without diabetes or dyslipidemia) was used for the analysis of circulating cytokines, MVs, miRNAs and MV-associated miRNAs.

RESULTS

The results uncovered three miRNAs, miR-218, miR-132 and miR-143, whose expression was found to be significantly up-regulated in both circulating MVs and plasma from diabetic patients with dyslipidemia. These miRNAs showed significant correlations with important plasma markers, representative of this pathology. Thus, MV/plasma miR-218 was negatively correlated with the levels of erythrocyte MVs, plasma miR-132 was positively connected with MV miR-132 and negatively with uric acid and erythrocyte plasma levels, and plasma miR-143 was negatively related with creatinine levels and diastolic blood pressure. Also, three miRNAs common to MV and plasma, namely miR-21, miR-122, and miR-155, were identified to be down-regulated and up-regulated, respectively, in diabetic dyslipidemia. In addition, MV miR-21 was positively linked with cholesterol plasma levels and plasma miR-21 with TNFα plasma levels, MV miR-122 was negatively correlated with LDL-c levels and plasma miR-122 with creatinine and diastolic blood pressure and positively with MV miR-126 levels, MV miR-155 was positively associated with cholesterol and total MV levels and negatively with HDL-c levels, whereas plasma miR-155 was positively correlated with Il-1β plasma levels and total MV levels and negatively with MV miR-223 levels.

CONCLUSIONS

In conclusion, miR-218, miR-132, miR-143, and miR-21, miR-122, miR-155 show potential as biomarkers for diabetic dyslipidemia, but there is a need for more in-depth studies. These findings bring new information regarding the molecular biomarkers specific to diabetic dyslipidemia and could have important implications for the treatment of patients affected by this pathology.

Extracellular Vesicles-The Next Frontier in Endocrinology

Extracellular vesicles (EVs), including exosomes, are emerging as important carriers of signals in normal and pathological physiology. As EVs are a long-range communication or signaling modality-just like hormones are-the field of endocrinology is uniquely poised to offer insight into their functional biology and regulation. EVs are membrane-bound particles secreted by many different cell types and can have local or systemic effects, being transported in body fluids. They express transmembrane proteins, some of which are shared between EVs and some being specific to the tissue of origin, that can interact with target cells directly (much like hormones can). They also contain cargo within them that includes DNA, RNA, miRNA, and various metabolites. They can fuse with target cells to empty their cargo and alter their target cell physiology in this way also. Similar to the endocrine system, the EV system is likely to be under homeostatic control, making the regulation of their biogenesis and secretion important aspects to study. In this review, we briefly highlight select examples of how EVs are implicated in normal physiology and disease states. We also discuss what is known about their biogenesis and regulation of secretion. We hope that this paper inspires the endocrinology field to use our collective expertise to explore these new multimodal "hormones."

Extracellular vesicles as signaling mediators in type 2 diabetes mellitus

Diabetes mellitus type 2, a chronic metabolic disease, has globally increased in incidence and prevalence throughout the lifespan due to the rise in obesity and sedentary lifestyle. The end-organ cardiovascular and cerebrovascular effects of diabetes mellitus result in significant morbidity and mortality that increases with age. Thus, it is crucial to fully understand how molecular mechanisms are influenced by diabetes mellitus and may influence the development of end-organ complications. Circulating factors are known to play important physiological and pathological roles in diabetes. Recent data have implicated extracellular vesicles (EVs) as being circulating mediators in type 2 diabetes. These small lipid-bound vesicles are released by cells into the circulation and can carry functional cargo, including lipids, proteins, and nucleic acids, to neighboring cells or between tissues. In this review, we will summarize the current evidence for EVs as promising diagnostic and prognostic factors in diabetes, the mechanisms that drive EV alterations with diabetes, and the role EVs play in the pathology associated with diabetes.

Microparticles and cardiovascular diseases

Microparticles are a distinctive group of small vesicles, without nucleus, which are involved as significant modulators in several physiological and pathophysiological mechanisms. Plasma microparticles from various cellular lines have been subject of research. Data suggest that they are key players in development and manifestation of cardiovascular diseases and their presence, in high levels, is associated with chronic inflammation, endothelial damage and thrombosis. The strong correlation of microparticle levels with several outcomes in cardiovascular diseases has led to their utilization as biomarkers. Despite the limited clinical application at present, their significance emerges, mainly because their detection and enumeration methods are improving. This review article summarizes the evidence derived from research, related with the genesis and the function of microparticles in the presence of various cardiovascular risk factors and conditions. The current data provide a substrate for several theories of how microparticles influence various cellular mechanisms by transferring biological information.

Review: Diabetes as a procoagulant condition

Major known effects of the metabolic derangements of diabetes in haemostasis are induction of platelet-vascular activation by hyperglycaemia, the increase in fibrinogen, modification of fibrin substrate by glucose and hypofibrinolysis related to insulin resistance. The platelet effects are specifically expressed during high shear stress and may be relevant in particular for developing of micro-angiopathy. Hypofibrinolysis, increased fibrinogen and modifications of fibrin may aggravate microthrombosis and organ damage and contribute to precipitation of coronary and cerebral infarction. In addition to specific anti-diabetic medication to reduce the haemostatic effects, specific antiplatelet and profibrinolytic treatments may be relevant for reducing further the morbidity and mortality in diabetics for both micro- and macro-angiopathy.

Activated Platelet and Oxidized LDL Induce Endothelial Membrane Vesiculation: Clinical Significance of Endothelial Cell-Derived Microparticles in Patients With Type 2 Diabetes

Endothelial cells, platelets, and oxidized LDL could play very important roles in the development of atherosclerosis in diabetes patients. The levels of plasma endothelial cell-derived microparticles (EDMP), platelet-derived microparticles (PDMP), platelet-P-selectin (plt-PS), soluble CD40 ligand (sCD40L), and anti-oxidized LDL antibody were measured and compared to develop a better understanding of their potential contribution to diabetic vascular complications. The concentrations of EDMP, PDMP, plt-PS, and sCD40L in diabetic patients were significantly higher than those in normal subjects. The number of EDMPs in patients with diabetes complicated by nephropathy was significantly higher than that in those without complications. Levels of anti-oxidized LDL antibody were also higher in type 2 diabetic patients than in control subjects. In addition, anti-oxidized LDL antibody levels correlated with EDMP, PDMP, plt-PS, and sCD40L levels in nephropathy patients. In the nephropathy group treated with sarpogrelate hydrochrolide, a 5-HT2A receptor antagonist, EDMP, PDMP, plt-PS, and sCD40L levels were decreased significantly. Oxidized LDL increased expression of plt-PS, and also promoted shedding of PDMP. Furthermore, oxidized LDL promoted a dose-dependent release of 5-hydroxytriptamine. On the other hand, activated platelets and PDMP promoted endothelial cells and THP-1 (monocytic cell line) interaction, and membrane vesiculation occurred in the presence of oxidized LDL. These findings suggest that activated platelets and oxidized LDL induce EDMP generation, and that elevated EDMPs may be a sign of vascular complications in type 2 diabetic patients, particularly those who suffer from diabetes-associated nephropathy

Innovative biomarkers for predicting type 2 diabetes mellitus: relevance to dietary management of frailty in older adults

Type 2 diabetes mellitus (T2DM) increases in prevalence in the elderly. There is evidence for significant muscle loss and accelerated cognitive impairment in older adults with T2DM; these comorbidities are critical features of frailty. In the early stages of T2DM, insulin sensitivity can be improved by a "healthy" diet. Management of insulin resistance by diet in people over 65 years of age should be carefully re-evaluated because of the risk for falling due to hypoglycaemia. To date, an optimal dietary programme for older adults with insulin resistance and T2DM has not been described. The use of biomarkers to identify those at risk for T2DM will enable clinicians to offer early dietary advice that will delay onset of disease and of frailty. Here we have used an in silico literature search for putative novel biomarkers of T2DM risk and frailty. We suggest that plasma bilirubin, plasma, urinary DPP4-positive microparticles and plasma pigment epithelium-derived factor merit further investigation as predictive biomarkers for T2DM and frailty risk in older adults. Bilirubin is screened routinely in clinical practice. Measurement of specific microparticle frequency in urine is less invasive than a blood sample so is a good choice for biomonitoring. Future studies should investigate whether early dietary changes, such as increased intake of whey protein and micronutrients that improve muscle function and insulin sensitivity, affect biomarkers and can reduce the longer term complication of frailty in people at risk for T2DM.

Minireview: Emerging Roles for Extracellular Vesicles in Diabetes and Related Metabolic Disorders

Extracellular vesicles (EVs), membrane-contained vesicles released by most cell types, have attracted a large amount of research interest over the past decade. Because of their ability to transfer cargo via regulated processes, causing functional impacts on recipient cells, these structures may play important roles in cell-cell communication and have implications in the physiology of numerous organ systems. In addition, EVs have been described in most human biofluids and have wide potential as relatively noninvasive biomarkers of various pathologic conditions. Specifically, EVs produced by the pancreatic β-cell have been demonstrated to regulate physiologic and pathologic responses to β-cell stress, including β-cell proliferation and apoptosis. β-Cell EVs are also capable of interacting with immune cells and may contribute to the activation of autoimmune processes that trigger or propagate β-cell inflammation and destruction during the development of diabetes. EVs from adipose tissue have been shown to contribute to the development of the chronic inflammation and insulin resistance associated with obesity and metabolic syndrome via interactions with other adipose, liver, and muscle cells. Circulating EVs may also serve as biomarkers for metabolic derangements and complications associated with diabetes. This minireview describes the properties of EVs in general, followed by a more focused review of the literature describing EVs affecting the β-cell, β-cell autoimmunity, and the development of insulin resistance, which all have the potential to affect development of type 1 or type 2 diabetes.

Microvesicles and diabetic complications--novel mediators, potential biomarkers and therapeutic targets

Microvesicles (MVs), also known as microparticles, are small membrane vesicles released from different cell types under different conditions. MVs have been detected in the circulation and in organs/tissues in various diseases, including diabetes. Patients with different types of diabetes and complications have different cellular MV patterns. Studies have shown that MVs may mediate vascular thrombosis, vascular inflammation, angiogenesis, and other pathological processes of the disease through their procoagulant, pro-inflammatory, pro-angiogenic, proteolytic, and other properties. Therefore, MVs contribute to the development of diabetic macrovascular and microvascular complications. In addition, clinical studies have indicated that changes in MV number and composition may reflect the pathophysiological conditions of disease, and therefore, may serve as potential biomarkers for diagnostic and prognostic use. Understanding MVs' involvement in the pathophysiological conditions may provide insight into disease mechanisms and would also be helpful for the development of novel therapeutic strategies in the future. Here, we review the latest publications from our group and other groups and focus on the involvement of MVs in diabetic complications.

Evaluation of the effectiveness of sarpogrelate on the surrogate markers for macrovascular complications in patients with type 2 diabetes

Sarpogrelate, a selective 5-HT(2) receptor antagonist, is known to have a significant effect on antiplatelet action. This study was a double-blinded, randomized, paralleled multicenter trial to compare the effects of sarpogrelate and aspirin on preventing macrovascular complications in patients with type 2 diabetes. The subjects were randomly assigned to either the sarpogrelateor the aspirin group. The baseline parameters for macrovascular complications, such as intima media thickness (IMT), ankle-brachial index (ABI), IL-6, serotonin, adiponectin, and hsCRP, were measured before drug administration. Changes were compared at 6 and 12 months after the administration of each drug. A total of 127 subjects (63 in the sarpogrelate group and 64 in the aspirin group) were pooled during the study period. No significant differences were found in baseline IMT or in other predictors of macrovascular complications. The mean IMT increased in both groups after 12 months, but there was no significant difference between the two groups. No significant change was found in the other predictors of macrovascular complications nor in the incidence of drug-related adverse events between the two groups. During the study period, no significant differences were found between the sarpogrelate group and aspirin group in the clinical indices or in the safety of the subjects related to macrovascular complications. This suggests that sarpogrelate may be clinically useful for the primary prevention of macrovascular complications in patients with type 2 diabetes.

Cardiovascular disease in diabetic nephropathy patients: cell adhesion molecules as potential markers?

Cardiovascular disease is a major complication of diabetes mellitus, especially for patients with diabetic nephropathy. The underlying factor or pathogenic mechanism that links diabetic nephropathy with cardiovascular disease is not known. The endothelial cell adhesion molecules, intercellular adhesion molecule-1 or vascular cell adhesion molecule-1, play a crucial role in the initiation of atherosclerosis. Levels of both cell adhesion molecules are raised by the diabetic and kidney disease states. This review focuses on these important cell adhesion molecules and their role in the pathogenesis of cardiovascular disease in diabetes and diabetic nephropathy.

Therapeutic Potentials of Sarpogrelate in Cardiovascular Disease*

In view of the pivotal role of serotonin (5-HT) in a wide variety of cardiovascular disorders, extensive effort has been made to develop different types of 5-HT receptor antagonists for therapeutic use. On the basis of experimental studies, this article is focused on the potentials of sarpogrelate, a specific 5-HT2A receptor antagonist as an antiplatelet, antithrombotic, antiatherosclerotic and antianginal agent. The major effects of sarpogrelate are due to the inhibition of 5-HT-induced platelet aggregation and smooth muscle cell proliferation. This agent was found to attenuate the 5-HT-mediated increase in intracellular Ca2+ and ischemia-reperfusion injury in the heart. Sarpogrelate has been found to have beneficial effects in peripheral vascular disease, restenosis after coronary stenting, pulmonary hypertension, acute and chronic myocardial infarction.

5-HT2A receptor antagonist increases circulating adiponectin in patients with type 2 diabetes

We compared the levels of plasma adiponectin, platelet activation markers (P-selectin, CD63, PAC-1, annexin V, and platelet-derived microparticles), and endothelial injury markers (soluble E-selectin and soluble vascular cell adhesion molecule-1) in 53 patients with type 2 diabetes mellitus to investigate potential contributions to diabetic vascular complications. In addition, we administered serotonin antagonist (sarpogrelate hydrochloride) to type 2 diabetes patients who had increased soluble E-selectin levels. The concentrations of platelet activation markers and endothelial injury markers in diabetic patients were significantly higher than those in normal subjects. However, levels of adiponectin were lower in type 2 diabetes patients than in control subjects. A total of 32 patients had high-soluble E-selectin levels (soluble E-selectin >or= 62 ng/ml); a subset of patients that also had significant elevation of platelet activation and endothelial injury markers compared with patients without high soluble E-selectin. In addition, both platelet-P-selectin and platelet-derived microparticle levels negatively correlated with the adiponectin level. Patients with high soluble E-selectin exhibited significant improvement of all markers after sarpogrelate hydrochloride treatment. These findings suggest that there is a link between vascular change in type 2 diabetes and activated platelets, endothelial dysfunction, and an adiponectin abnormality.

Sarpogrelate: cardiovascular and renal clinical potential

Sarpogrelate is a selective 5-hydroxytryptamine receptor subtype 2A (5-HT2A) antagonist. It is metabolised to racemic M-1 and both enantiomers of M-1 are also antagonists of 5-HT2A receptors. Sarpogrelate inhibits responses to 5-HT mediated by 5-HT2A receptors such as platelet aggregation, vasoconstriction and vascular smooth muscle proliferation. There is no information available on the pharmacokinetics of sarpogrelate. Sarpogrelate is efficacious in animal models of thrombosis, coronary artery spasm, atherosclerosis, restenosis, peripheral vascular disease, pulmonary hypertension, ischaemic heart disease, myocardial infarction, diabetes and kidney disease. Small clinical trials indicate that sarpogrelate may be beneficial in the treatment of coronary artery disease, angina, restenosis, heart valve prostheses surgery, diabetes mellitus, Raynaud's phenomenon, systemic sclerosis and Buerger's disease. Larger, randomised, double-blind, placebo-controlled clinical trials of sarpogrelate in intermittent claudication, coronary artery disease, restenosis and diabetes should be considered.

Activated platelets induce Weibel-Palade-body secretion and leukocyte rolling in vivo: role of P-selectin

The presence of activated platelets and platelet-leukocyte aggregates in the circulation accompanies major surgical procedures and occurs in several chronic diseases. Recent findings that activated platelets contribute to the inflammatory disease atherosclerosis made us address the question whether activated platelets stimulate normal healthy endothelium. Infusion of activated platelets into young mice led to the formation of transient platelet-leukocyte aggregates and resulted in a several-fold systemic increase in leukocyte rolling 2 to 4 hours after infusion. Rolling returned to baseline levels 7 hours after infusion. Infusion of activated P-selectin-/- platelets did not induce leukocyte rolling, indicating that platelet P-selectin was involved in the endothelial activation. The endothelial activation did not require platelet CD40L. Leukocyte rolling was mediated solely by the interaction of endothelial P-selectin and leukocyte P-selectin glycoprotein ligand 1 (PSGL-1). Endothelial P-selectin is stored with von Willebrand factor (VWF) in Weibel-Palade bodies. The release of Weibel-Palade bodies on infusion of activated platelets was indicated by both elevation of plasma VWF levels and by an increase in the in vivo staining of endothelial P-selectin. We conclude that the presence of activated platelets in circulation promotes acute inflammation by stimulating secretion of Weibel-Palade bodies and P-selectin-mediated leukocyte rolling.

Increased levels of platelet-derived microparticles in patients with diabetic retinopathy

Diabetic retinopathy is caused by capillary occlusions. Platelet-derived microparticles (PMPs) stimulate the coagulation cascade and increase leukocyte and endothelial cell adhesions, both of which are key events in the development of diabetic retinopathy. However, the correlation between the levels of PMPs and diabetic retinopathy has not been precisely determined. The PMPs levels and the expression of platelet CD62P and CD63 were measured in 92 diabetic patients. The level of PMPs was significantly correlated with the expression of CD62P (r = 0.76, P < 0.0001) and CD63 (r = 0.71, P < 0.0001). The mean level of PMPs in diabetics (507+/-15/10(4) platelets (plt), mean+/-S.E.) was significantly higher than that in normal. The PMPs levels increased with the progression of the diabetic retinopathy; 480+/-28/10(4) plt in diabetic patients without retinopathy (n = 25), 504+/-40/10(4) plt with mild or moderate non-proliferative diabetic retinopathy (n = 13), 512+/-29/10(4) plt with severe non-proliferative diabetic retinopathy (n = 25), and 528+/-25/10(4) plt with proliferative diabetic retinopathy (n=29). The PMPs level in patients with non-perfused retinal areas (582+/-27/10(4) plt, n = 24) was significantly higher than patients without non-perfused areas (469+/-23/10(4) plt, n = 30; P = 0.0096) and without diabetic retinopathy (P = 0.024). These high correlations indicate that increased levels of PMPs may accelerate diabetic retinopathy.

Effect of ticlopidine on monocyte-derived microparticles and activated platelet markers in diabetes mellitus

Platelet-derived microparticles, activated platelets, and monocyte-derived microparticles were measured in 73 patients with diabetes mellitus. A comparative study of these parameters was performed before and after administration of ticlopidine. The number of platelet-derived microparticles and activated platelets was increased significantly in diabetic patients. Monocyte-derived microparticles were also increased significantly. After administration of ticlopidine, platelet-derived microparticles and activated platelets corrected positively, not only CD62P- and CD63-positive platelets, but also platelet-derived microparticles and monocyte-derived microparticles showed a significant decrease. These data suggest that in patients with diabetes, platelet-derived microparticles and activated platelets stimulate the activation of monocytes and promote the production of monocyte-derived microparticles, and that ticlopidine is useful for hypercoagulabillity in diabetic patients.

Enhancing effect of advanced glycation end products on serotonin-induced platelet aggregation in patients with diabetes mellitus

Advanced glycation end products (AGEs) are thought to be responsible for some complications of diabetes mellitus (DM), including microangiopathy. Plasma serotonin is increased in diabetes mellitus patients, and this increase is related, at least in part, to platelet hyperfunction. In order to clarify the relationship between advanced glycation end products, serotonin, and thrombotic complications in diabetes mellitus patients, we examined the effect of advanced glycation end products on serotonin-induced platelet aggregation. In diabetic patients, although serotonin-induced platelet aggregation was enhanced with an increase in serum-advanced glycation end products, there was no correlation between platelet aggregation and either hemoglobin A1c or fasting blood sugar. To examine the direct effect of advanced glycation end products on platelet aggregation, we prepared advanced glycation end products by in vitro incubation of human albumin with glucose (250 mM) at 37 degrees C for 8 weeks. Serotonin-induced platelet aggregation was dose-dependently increased by advanced glycation end products. Adenosine diphosphate-induced platelet aggregation also was increased by advanced glycation end products, but this increment was diminished by addition of sarpogrelate, a selective serotonin receptor antagonist. These results suggest that advanced glycation end products enhance platelet aggregation through the serotonin receptor, and perhaps influencing the development of thrombotic complications in diabetic patients.

Type 1 and type 2 diabetic patients display different patterns of cellular microparticles

The development of vasculopathies in diabetes involves multifactorial processes including pathological activation of vascular cells. Release of microparticles by activated cells has been reported in diseases associated with thrombotic risk, but few data are available in diabetes. The aim of the present work was to explore the number and the procoagulant activity of cell-derived microparticles in type 1 and 2 diabetic patients. Compared with age-matched control subjects, type 1 diabetic patients presented significantly higher numbers of platelet and endothelial microparticles (PMP and EMP), total annexin V-positive blood cell microparticles (TMP), and increased levels of TMP-associated procoagulant activity. In type 2 diabetic patients, only TMP levels were significantly higher without concomitant increase of their procoagulant activity. Interestingly, in type 1 diabetic patients, TMP procoagulant activity was correlated with HbA(1c), suggesting that procoagulant activity is associated with glucose imbalance. These results showed that a wide vesiculation process, resulting from activation or apoptosis of several cell types, occurs in diabetes. However, diabetic patients differ by the procoagulant activity and the cellular origin of microparticles. In type 1 diabetic patients, TMP-procoagulant activity could be involved in vascular complications. Moreover, its correlation with HbA(1c) reinforces the importance of an optimal glycemic control in type 1 diabetes.

Function and clinical significance of platelet-derived microparticles

Microparticles released from platelets (PMPs) may play a role in the normal hemostatic response to vascular injury because they demonstrate prothrombinase activity. PMPs were first observed as released vesicles from platelets following adhesion to vessel walls, and flow cytometry is now the most widely used method for studying PMPs. PMPs are thought to play a role in clinical disease because they express phospholipids that function as procoagulants. High shear stress can initiate both platelet aggregation and shedding of procoagulant-containing PMP, suggesting that PMP generation by high shear stress occurs in small diseased arteries and arterioles under various clinical conditions. In addition, the possibility that PMPs evoke cellular responses in their immediate microenvironments has recently been suggested. Despite many interesting findings, the significance of PMPs in various clinical conditions remains controversial. For example, it is not known whether PMPs found in peripheral blood vessels cause thrombosis, or if they are the results of thrombosis. There has been some question about whether the PMPs found in thromboses are consumed locally, meaning that PMPs circulating in the peripheral blood are not functionally important. Currently, the number of clinical disorders associated with elevated PMPs is increasing.