Scanning electron microscopy of fibrin networks in rheumatoid arthritis: a qualitative analysis

A Direct Relationship Between 'Blood Stasis' and Fibrinaloid Microclots in Chronic, Inflammatory, and Vascular Diseases, and Some Traditional Natural Products Approaches to Treatment

'Blood stasis' (syndrome) (BSS) is a fundamental concept in Traditional Chinese Medicine (TCM), where it is known as Xue Yu (). Similar concepts exist in Traditional Korean Medicine ('Eohyul') and in Japanese Kampo medicine (Oketsu). Blood stasis is considered to underpin a large variety of inflammatory diseases, though an exact equivalent in Western systems medicine is yet to be described. Some time ago we discovered that blood can clot into an anomalous amyloid form, creating what we have referred to as fibrinaloid microclots. These microclots occur in a great many chronic, inflammatory diseases are comparatively resistant to fibrinolysis, and thus have the ability to block microcapillaries and hence lower oxygen transfer to tissues, with multiple pathological consequences. We here develop the idea that it is precisely the fibrinaloid microclots that relate to, and are largely mechanistically responsible for, the traditional concept of blood stasis (a term also used by Virchow). First, the diseases known to be associated with microclots are all associated with blood stasis. Secondly, by blocking red blood cell transport, fibrinaloid microclots provide a simple mechanistic explanation for the physical slowing down ('stasis') of blood flow. Thirdly, Chinese herbal medicine formulae proposed to treat these diseases, especially Xue Fu Zhu Yu and its derivatives, are known mechanistically to be anticoagulatory and anti-inflammatory, consistent with the idea that they are actually helping to lower the levels of fibrinaloid microclots, plausibly in part by blocking catalysis of the polymerization of fibrinogen into an amyloid form. We rehearse some of the known actions of the constituent herbs of Xue Fu Zhu Yu and specific bioactive molecules that they contain. Consequently, such herbal formulations (and some of their components), which are comparatively little known to Western science and medicine, would seem to offer the opportunity to provide novel, safe, and useful treatments for chronic inflammatory diseases that display fibrinaloid microclots, including Myalgic Encephalopathy/Chronic Fatigue Syndrome, long COVID, and even ischemic stroke.

Post-translational modifications of fibrinogen: implications for clotting, fibrin structure and degradation

Fibrinogen, a blood plasma protein with a key role in hemostasis and thrombosis, is highly susceptible to post-translational modifications (PTMs), that significantly influence clot formation, structure, and stability. These PTMs, which include acetylation, amidation, carbamylation, citrullination, dichlorination, glycation, glycosylation, guanidinylation, hydroxylation, homocysteinylation, malonylation, methylation, nitration, oxidation, phosphorylation and sulphation, can alter fibrinogen biochemical properties and affect its functional behavior in coagulation and fibrinolysis. Oxidation and nitration are notably associated with oxidative stress, impacting fibrin fiber formation and promoting the development of more compact and resistant fibrin networks. Glycosylation and glycation contribute to altered fibrinogen structural properties, often resulting in changes in fibrin clot density and susceptibility to lysis, particularly in metabolic disorders like diabetes. Acetylation and phosphorylation, influenced by medications such as aspirin, modulate clot architecture by affecting fiber thickness and clot permeability. Citrullination and homocysteinylation, although less studied, are linked to autoimmune conditions and cardiovascular diseases, respectively, affecting fibrin formation and stability. Understanding these modifications provides insights into the pathophysiology of thrombotic disorders and highlights potential therapeutic targets. This review comprehensively examines the current literature on fibrinogen PTMs, their specific sites, biochemical pathways, and their consequences on fibrin clot architecture, clot formation and clot lysis.

Management of a Patient with Cardiovascular Disease Should Include Assessment of Primary and Secondary Immunodeficiencies: Part 2-Secondary Immunodeficiencies

BACKGROUND

Cardiovascular diseases are among the most common chronic diseases, generating high social and economic costs. Secondary immunodeficiencies occur more often than primary ones and may result from the co-occurrence of specific diseases, treatment, nutrient deficiencies and non-nutritive bio-active compounds that result from the industrial nutrient practices.

OBJECTIVES

The aim of this article is to present selected secondary immunodeficiencies and their impact on the cardiovascular system.

RESULTS

The treatment of a patient with cardiovascular disease should include an assess-ment for immunodeficiencies, because the immune and cardiovascular systems are closely linked.

CONCLUSIONS

Immune system dysfunctions can significantly affect the course of cardiovascular diseases and their treatment. For this reason, comprehensive care for a patient with cardiovascular disease requires taking into account potential immunodeficiencies, which can have a significant impact on the patient's health.

Fibrinaloid Microclots and Atrial Fibrillation

Atrial fibrillation (AF) is a comorbidity of a variety of other chronic, inflammatory diseases for which fibrinaloid microclots are a known accompaniment (and in some cases, a cause, with a mechanistic basis). Clots are, of course, a well-known consequence of atrial fibrillation. We here ask the question whether the fibrinaloid microclots seen in plasma or serum may in fact also be a cause of (or contributor to) the development of AF. We consider known 'risk factors' for AF, and in particular, exogenous stimuli such as infection and air pollution by particulates, both of which are known to cause AF. The external accompaniments of both bacterial (lipopolysaccharide and lipoteichoic acids) and viral (SARS-CoV-2 spike protein) infections are known to stimulate fibrinaloid microclots when added in vitro, and fibrinaloid microclots, as with other amyloid proteins, can be cytotoxic, both by inducing hypoxia/reperfusion and by other means. Strokes and thromboembolisms are also common consequences of AF. Consequently, taking a systems approach, we review the considerable evidence in detail, which leads us to suggest that it is likely that microclots may well have an aetiological role in the development of AF. This has significant mechanistic and therapeutic implications.

Are fibrinaloid microclots a cause of autoimmunity in Long Covid and other post-infection diseases?

It is now well established that the blood-clotting protein fibrinogen can polymerise into an anomalous form of fibrin that is amyloid in character; the resultant clots and microclots entrap many other molecules, stain with fluorogenic amyloid stains, are rather resistant to fibrinolysis, can block up microcapillaries, are implicated in a variety of diseases including Long COVID, and have been referred to as fibrinaloids. A necessary corollary of this anomalous polymerisation is the generation of novel epitopes in proteins that would normally be seen as 'self', and otherwise immunologically silent. The precise conformation of the resulting fibrinaloid clots (that, as with prions and classical amyloid proteins, can adopt multiple, stable conformations) must depend on the existing small molecules and metal ions that the fibrinogen may (and is some cases is known to) have bound before polymerisation. Any such novel epitopes, however, are likely to lead to the generation of autoantibodies. A convergent phenomenology, including distinct conformations and seeding of the anomalous form for initiation and propagation, is emerging to link knowledge in prions, prionoids, amyloids and now fibrinaloids. We here summarise the evidence for the above reasoning, which has substantial implications for our understanding of the genesis of autoimmunity (and the possible prevention thereof) based on the primary process of fibrinaloid formation.

Formation of Hydroxyapatite-Based Hybrid Materials in the Presence of Platelet-Poor Plasma Additive

Biomaterials based on hydroxyapatite with controllable composition and properties are promising in the field of regenerative bone replacement. One approach to regulate the phase composition of the materials is the introduction of biopolymer-based additives into the synthesis process. The purpose of present study was to investigate the formation of hydroxyapatite-based hybrid materials in the presence of 6-24% platelet-poor plasma (PPP) additive, at a [Ca2+]/[PO43-] ratio of 1.67, pH 11, and varying maturing time from 4 to 9 days. The mineral component of the materials comprised 53% hydroxyapatite/47% amorphous calcium phosphate after 4 days of maturation and 100% hydroxyapatite after 9 days of maturation. Varying the PPP content between 6% and 24% brought about the formation of materials with rather defined contents of amorphous calcium phosphate and biopolymer component and the desired morphology, ranging from typical apatitic conglomerates to hybrid apatite-biopolymer fibers. The co-precipitated hybrid materials based on hydroxyapatite, amorphous calcium phosphate, and PPP additive exhibited increased solubility in SBF solution, which defines their applicability for repairing rhinoplastic defects.

Fibrin clot properties in cardiovascular disease: from basic mechanisms to clinical practice

Fibrinogen conversion into insoluble fibrin and the formation of a stable clot is the final step of the coagulation cascade. Fibrin clot porosity and its susceptibility to plasmin-mediated lysis are the key fibrin measures, describing the properties of clots prepared ex vivo from citrated plasma. Cardiovascular disease (CVD), referring to coronary heart disease, heart failure, stroke, and hypertension, has been shown to be associated with the formation of dense fibrin networks that are relatively resistant to lysis. Denser fibrin mesh characterized acute patients at the onset of myocardial infarction or ischaemic stroke, while hypofibrinolysis has been identified as a persistent fibrin feature in patients following thrombotic events or in those with stable coronary artery disease. Traditional cardiovascular risk factors, such as smoking, diabetes mellitus, hyperlipidaemia, obesity, and hypertension, have also been linked with unfavourably altered fibrin clot properties, while some lifestyle modifications and pharmacological treatment, in particular statins and anticoagulants, may improve fibrin structure and function. Prospective studies have suggested that prothrombotic fibrin clot phenotype can predict cardiovascular events in short- and long-term follow-ups. Mutations and splice variants of the fibrinogen molecule that have been proved to be associated with thrombophilia or increased cardiovascular risk, along with fibrinogen post-translational modifications, prothrombotic state, inflammation, platelet activation, and neutrophil extracellular traps formation, contribute also to prothrombotic fibrin clot phenotype. Moreover, about 500 clot-bound proteins have been identified within plasma fibrin clots, including fibronectin, α2-antiplasmin, factor XIII, complement component C3, and histidine-rich glycoprotein. This review summarizes the current knowledge on the mechanisms underlying unfavourable fibrin clot properties and their implications in CVD and its thrombo-embolic manifestations.

Inhibitory Effect of Jinwujiangu Prescription on Peripheral Blood Osteoclasts in Patients with Rheumatoid Arthritis and the Relevant Molecular Mechanism

Rheumatoid arthritis (RA) is a chronic progressive autoimmune disease characterized with high recurrence, high disability, poor prognosis, and long treatment cycles. Versus western medicine, traditional Chinese medicine has the traits of definite efficacy, low toxicity, and side effects in the treatment of RA. Moreover, traditional Chinese medicine also has the advantages of multiple targets, multiple links, and multiple approaches. This study was committed to exploring the effect of Jinwujiangu prescription on peripheral blood osteoclasts in those patients with RA and relevant molecular mechanisms. We first identified 159 common targets by online pharmacology, and there were correlations among these targets; besides, the main signaling pathways involved were inclusive TNF signaling pathway, rheumatoid arthritis, IL-17 signaling pathway, NF-kappa B signaling pathway, Toll-like receptor signaling pathway, etc. Through experimental verification, we found that PBMC cells extracted from human peripheral blood could be successfully induced into osteoclasts, and Jinwujiangu prescription inhibited the generation of osteoclasts from PBMCs of RA patients. CCK-8 and flow cytometry showed that osteoclast viability was significantly decreased and osteoclast apoptosis was significantly increased in the HIF-1α interference group; low-, medium-, and high-dose Jinwujiangu prescription groups; sinapine group; and hydroxychloroquine control group. Moreover, Jinwujiangu prescription and sinapine could inhibit the production of cytokines in peripheral blood osteoclasts and inhibit autophagy in RA patients. The expression level of mTOR was significantly increased in both Jinwu middle- and high-dose groups. In conclusion, this study demonstrated that sinapine, the active target in Jinwujiangu prescription, can act as a HIF-1α inhibitor; activate the mTOR pathway; downregulate the level of autophagy rate, ATG5, beclin-1, and LC3 expression; and inhibit the occurrence of autophagy. The trial registration number of the study is KYW2021010.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia-reperfusion (I-R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I-R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

A central role for amyloid fibrin microclots in long COVID/PASC: origins and therapeutic implications

Post-acute sequelae of COVID (PASC), usually referred to as 'Long COVID' (a phenotype of COVID-19), is a relatively frequent consequence of SARS-CoV-2 infection, in which symptoms such as breathlessness, fatigue, 'brain fog', tissue damage, inflammation, and coagulopathies (dysfunctions of the blood coagulation system) persist long after the initial infection. It bears similarities to other post-viral syndromes, and to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Many regulatory health bodies still do not recognize this syndrome as a separate disease entity, and refer to it under the broad terminology of 'COVID', although its demographics are quite different from those of acute COVID-19. A few years ago, we discovered that fibrinogen in blood can clot into an anomalous 'amyloid' form of fibrin that (like other β-rich amyloids and prions) is relatively resistant to proteolysis (fibrinolysis). The result, as is strongly manifested in platelet-poor plasma (PPP) of individuals with Long COVID, is extensive fibrin amyloid microclots that can persist, can entrap other proteins, and that may lead to the production of various autoantibodies. These microclots are more-or-less easily measured in PPP with the stain thioflavin T and a simple fluorescence microscope. Although the symptoms of Long COVID are multifarious, we here argue that the ability of these fibrin amyloid microclots (fibrinaloids) to block up capillaries, and thus to limit the passage of red blood cells and hence O2 exchange, can actually underpin the majority of these symptoms. Consistent with this, in a preliminary report, it has been shown that suitable and closely monitored 'triple' anticoagulant therapy that leads to the removal of the microclots also removes the other symptoms. Fibrin amyloid microclots represent a novel and potentially important target for both the understanding and treatment of Long COVID and related disorders.

Detection of Citrullinated Fibrin in Plasma Clots of Rheumatoid Arthritis Patients and Its Relation to Altered Structural Clot Properties, Disease-Related Inflammation and Prothrombotic Tendency

Aims

The risk of cardiovascular events in patients with Rheumatoid Arthritis (RA) is disproportionately heightened as a result of systemic inflammation. The relative effect of autoimmune-associated citrullination on the structure and thrombotic potential of fibrin(ogen) remains unknown. We therefore compared indices of vascular function, inflammation, coagulation and fibrin clot composition in RA patients with healthy controls and evaluated parameter association with disease presence.

Methods

Blood samples were collected from 30 RA patients and 30 age- and gender-matched healthy volunteers. Levels of serum amyloid A (SAA), c-reactive protein (CRP), soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule 1 (sVCAM-1) was measured using a sandwich immunoassay. Whole blood coagulation was assessed using Thromboelastography (TEG^®). Fibrin clot networks and fiber structure was investigated using Scanning Electron Microscopy. The detection and quantification of citrullination in formed fibrin clots was performed using a fluorescently labeled Citrulline monoclonal antibody with Fluorescence Wide Field Microscopy.

Results

Concentrations of SAA, CRP and ICAM-1 were significantly elevated in RA patients compared to controls. TEG parameters relating to coagulation initiation, rate of fibrin cross-linking, and time to reach maximum thrombus generation were attenuated in RA patients. Microscopic analysis revealed denser networks of thicker fibrin fibers in RA patients compared to controls and multiple citrullinated regions within fibrin clot structures in RA patients were present.

Conclusion

Our findings provide novel evidence for the citrullination of fibrin within vasculature is more prominent in RA plasma compared to control plasma and plasma is more accessible than synovial fluid. Citrullinated fibrinogen could play a role as a determinant of thrombotic risk in RA patients.

Bioprinting of Vascularized Tissue Scaffolds: Influence of Biopolymer, Cells, Growth Factors, and Gene Delivery

Over the past decades, tissue regeneration with scaffolds has achieved significant progress that would eventually be able to solve the worldwide crisis of tissue and organ regeneration. While the recent advancement in additive manufacturing technique has facilitated the biofabrication of scaffolds mimicking the host tissue, thick tissue regeneration remains challenging to date due to the growing complexity of interconnected, stable, and functional vascular network within the scaffold. Since the biological performance of scaffolds affects the blood vessel regeneration process, perfect selection and manipulation of biological factors (i.e., biopolymers, cells, growth factors, and gene delivery) are required to grow capillary and macro blood vessels. Therefore, in this study, a brief review has been presented regarding the recent progress in vasculature formation using single, dual, or multiple biological factors. Besides, a number of ways have been presented to incorporate these factors into scaffolds. The merits and shortcomings associated with the application of each factor have been highlighted, and future research direction has been suggested.

A fibrin biofilm covers blood clots and protects from microbial invasion

Hemostasis requires conversion of fibrinogen to fibrin fibers that generate a characteristic network, interact with blood cells, and initiate tissue repair. The fibrin network is porous and highly permeable, but the spatial arrangement of the external clot face is unknown. Here we show that fibrin transitioned to the blood-air interface through Langmuir film formation, producing a protective film confining clots in human and mouse models. We demonstrated that only fibrin is required for formation of the film, and that it occurred in vitro and in vivo. The fibrin film connected to the underlying clot network through tethering fibers. It was digested by plasmin, and formation of the film was prevented with surfactants. Functionally, the film retained blood cells and protected against penetration by bacterial pathogens in a murine model of dermal infection. Our data show a remarkable aspect of blood clotting in which fibrin forms a protective film covering the external surface of the clot, defending the organism against microbial invasion.

Lipopolysaccharide-binding protein (LBP) can reverse the amyloid state of fibrin seen or induced in Parkinson's disease

The thrombin-induced polymerisation of fibrinogen to form fibrin is well established as a late stage of blood clotting. It is known that Parkinson's Disease (PD) is accompanied by dysregulation in blood clotting, but it is less widely known as a coagulopathy. In recent work, we showed that the presence of tiny amounts of bacterial lipopolysaccharide (LPS) in healthy individuals could cause clots to adopt an amyloid form, and this could be observed via scanning electron microscopy (SEM) or via the fluorescence of thioflavin-T. This could be prevented by the prior addition of lipopolysaccharide-binding protein (LBP). We had also observed by SEM this unusual clotting in the blood of patients with Parkinson's Disease. We hypothesised, and here show, that this too can be prevented by LBP in the context of PD. This adds further evidence implicating inflammatory microbial cell wall products as an accompaniment to the disease, and may be part of its aetiology. This may lead to novel treatment strategies in PD designed to target microbes and their products.

Carbon Monoxide and Its Controlled Release: Therapeutic Application, Detection, and Development of Carbon Monoxide Releasing Molecules (CORMs)

Carbon monoxide (CO) is attracting increasing attention because of its role as a gasotransmitter with cytoprotective and homeostatic properties. Carbon monoxide releasing molecules (CORMs) are spatially and temporally controlled CO releasers that exhibit superior and more effective pharmaceutical traits than gaseous CO because of their chemistry and structure. Experimental and preclinical research in animal models has shown the therapeutic potential of inhaled CO and CORMs, and the biological effects of CO and CORMs have also been observed in preclinical trials via the genetic modulation of heme oxygenase-1 (HO-1). In this review, we describe the pharmaceutical use of CO and CORMs, methods of detecting CO release, and developments in CORM design and synthesis. Many valuable clinical CORMs formulated using macromolecules and nanomaterials are also described.

Impact of fibrinogen carbamylation on fibrin clot formation and stability

Carbamylation is a non-enzymatic post-translational modification induced upon exposure of free amino groups to urea-derived cyanate leading to irreversible changes of protein charge, structure and function. Levels of carbamylated proteins increase significantly in chronic kidney disease and carbamylated albumin is considered as an important biomarker indicating mortality risk. High plasma concentrations and long half-life make fibrinogen a prime target for carbamylation. As aggregation and cross-linking of fibrin monomers rely on lysine residues, it is likely that carbamylation impacts fibrinogen processing. In this study we investigated carbamylation levels of fibrinogen from kidney disease patients as well as the impact of carbamylation on fibrinogen cleavage by thrombin, fibrin polymerisation and cross-linking in vitro. In conjunction, all these factors determine clot structure and stability and thus control biochemical and mechanical properties. LC-MS/MS analyses revealed significantly higher homocitrulline levels in patient fibrinogen than in fibrinogen isolated from control plasma. In our in vitro studies we found that although carbamylation does not affect thrombin cleavage per se, it alters fibrin polymerisation kinetics and impairs cross-linking and clot degradation. In addition, carbamylated fibrin clots had reduced fiber size and porosity associated with decreased mechanical stability. Using mass spectroscopy, we discovered that N-terminally carbamylated fibrinopeptide A was generated in this process and acted as a strong neutrophil chemoattractant potentially mediating recruitment of inflammatory cells to sites of fibrin(ogen) turnover. Taken together, carbamylation of fibrinogen seems to play a role in aberrant fibrin clot formation and might be involved in haemostatic disorders associated with chronic inflammatory diseases.

Viscoelastic and ultrastructural characteristics of whole blood and plasma in Alzheimer-type dementia, and the possible role of bacterial lipopolysaccharides (LPS)

Alzheimer-type dementia (AD) is a neurodegenerative disorder and the most common form of dementia. Patients typically present with neuro- and systemic inflammation and iron dysregulation, associated with oxidative damage that reflects in hypercoagulability. Hypercoagulability is closely associated with increased fibrin(ogen) and in AD patients fibrin(ogen) has been implicated in the development of neuroinflammation and memory deficits. There is still no clear reason precisely why (a) this hypercoagulable state, (b) iron dysregulation and (c) increased fibrin(ogen) could together lead to the loss of neuronal structure and cognitive function. Here we suggest an alternative hypothesis based on previous ultrastructural evidence of the presence of a (dormant) blood microbiome in AD. Furthermore, we argue that bacterial cell wall components, such as the endotoxin lipopolysaccharide (LPS) of Gram-negative strains, might be the cause of the continuing and low-grade inflammation, characteristic of AD. Here, we follow an integrated approach, by studying the viscoelastic and ultrastructural properties of AD plasma and whole blood by using scanning electron microscopy, Thromboelastography (TEG^®) and the Global Thrombosis Test (GTT^®). Ultrastructural analysis confirmed the presence and close proximity of microbes to erythrocytes. TEG^® analysis showed a hypercoagulable state in AD. TEG^® results where LPS was added to naive blood showed the same trends as were found with the AD patients, while the GTT^® results (where only platelet activity is measured), were not affected by the added LPS, suggesting that LPS does not directly impact platelet function. Our findings reinforce the importance of further investigating the role of LPS in AD.

Clinical relevance of fibrin fiber diameter during different phases of pregnancy

INTRODUCTION

Pregnancy-related deep vein thrombosis (DVT) is most common during the late phase of pregnancy and the first 6-weeks postpartum. Pregnancy-related DVT can have long-term complications, specifically post-thrombotic syndrome (PTS). Fibrin network ultrastructure is altered during pregnancy and post-partum. It is therefore essential to evaluate fibrin fiber diameter during and after pregnancy as this may provide insight into pregnancy-related DVT and subsequent PTS.

MATERIALS AND METHODS

The fibrin network ultrastructure of females during different phases of pregnancy was compared to that of non-pregnant females to assess possible changes to the fibrin network morphology and fibrin fiber diameter using scanning electron microscopy micrographs.

RESULTS

The fibrin network arrangement was more densely packed during different phases of pregnancy, corresponding to earlier findings. Fibrin diameter decreased significantly during pregnancy, with the greatest decrease occurring during the late phase of pregnancy. The fractal dimensions of fibrin micrographs increased significantly during pregnancy compared to nonpregnant females. These changes are indicative of a simultaneous hypercoagulable and hypofibrinolytic state and correspond to the increased risk of DVT and subsequent development of PTS.

CONCLUSION

It is critical to identify "vulnerable" females with an inflammatory predisposition to prevent possible DVT and subsequent PTS. Modifiable risk factors like obesity and smoking should be addressed to alleviate the burden on the coagulation system. Morphological and viscoelastic techniques are crucial in assessing the coagulatory health of females during pregnancy.

Viscoelasticity and Ultrastructure in Coagulation and Inflammation: Two Diverse Techniques, One Conclusion

The process of blood clotting has been studied for centuries. A synopsis of current knowledge pertaining to haemostasis and the blood components, including platelets and fibrin networks which are closely involved in coagulation, are discussed. Special emphasis is placed on tissue factor (TF), calcium and thrombin since these components have been implicated in both the coagulation process and inflammation. Analysis of platelets and fibrin morphology indicate that calcium, tissue factor and thrombin at concentrations used during viscoelastic analysis (with thromboelastography or TEG) bring about alterations in platelet and fibrin network ultrastructure, which is similar to that seen in inflammation. Scanning electron microscopy indicated that, when investigating platelet structure in disease, addition of TF, calcium or thrombin will mask disease-induced alterations associated with platelet activation. Therefore, washed platelets without any additives is preferred for morphological analysis. Furthermore, morphological and viscoelastic analysis confirmed that thrombin activation is the preferred method of fibrin activation when investigating fibrin network ultrastructure.

Iron-enhanced coagulation is attenuated by chelation: thrombelastographic and ultrastructural analysis

Increased circulating ferritin and free iron have been found in a variety of disease states associated with thrombophilia. When blood or plasma is exposed to iron addition, characteristic changes in thrombus formation are observed by scanning electron microscopy, which include fusion of fibrin polymers, matting, and even sheeting of fibrin. A primary mechanism posited to explain iron-mediated hypercoagulability is hydroxyl radical formation and modification of fibrinogen; however, iron has also been demonstrated to bind to fibrinogen. We have recently demonstrated that iron enhances coagulation, manifested as a decrease in the time of onset of coagulation. Using clinically encountered concentrations of iron created by addition of FeCl3 to human plasma, we demonstrated that iron-mediated changes in reaction time determined by thrombelastography or changes in thrombus ultrastructure were significantly, but not completely, reversed by iron chelation with deferoxamine. Thus, reversible iron binding to fibrinogen mechanistically explains a significant portion of coagulation kinetic and ultrastructural hypercoagulability. Further investigation is needed to determine whether residual iron binding or other iron-mediated effects is responsible for hypercoagulability observed after chelation.

Iron and carbon monoxide enhance coagulation and attenuate fibrinolysis by different mechanisms

Two parallel lines of investigation elucidating novel mechanisms by which iron (scanning electron microscopy-based) and carbon monoxide (viscoelastic-based) enhance coagulation and diminish fibrinolysis have emerged over the past few years. However, a multimodal approach to ascertain the effects of iron and carbon monoxide remained to be performed. Such investigation could be important, as iron and carbon monoxide are two of the products of heme catabolism via heme oxygenase-1, an enzyme upregulated in a variety of disease states associated with thrombophilia. Human plasma was exposed to ferric chloride, carbon monoxide derived from carbon monoxide-releasing molecule-2, or their combination. Viscoelastic studies demonstrated ferric chloride and carbon monoxide mediated enhancement of velocity of growth, and final clot strength, with the combination of the two molecules noted to have all the prothrombotic kinetic effects of either separately. Parallel ultrastructural studies demonstrated separate types of fibrin polymer cross-linking and matting in plasma exposed to ferric chloride and carbon monoxide, with the combination sharing features of each molecule. In conclusion, we present the first evidence that iron and carbon monoxide interact with key coagulation and fibrinolytic processes, resulting in thrombi that begin to form more quickly, grow faster, become stronger, and are more resistant to lysis.

Diagnostic morphology: biophysical indicators for iron-driven inflammatory diseases

Most non-communicable diseases involve inflammatory changes in one or more vascular systems, and there is considerable evidence that unliganded iron plays major roles in this. Most studies concentrate on biochemical changes, but there are important biophysical correlates. Here we summarize recent microscopy-based observations to the effect that iron can have major effects on erythrocyte morphology, on erythrocyte deformability and on both fibrinogen polymerization and the consequent structure of the fibrin clots formed, each of which contributes significantly and negatively to such diseases. We highlight in particular type 2 diabetes mellitus, ischemic thrombotic stroke, systemic lupus erythematosus, hereditary hemochromatosis and Alzheimer's disease, while recognizing that many other diseases have co-morbidities (and similar causes). Inflammatory biomarkers such as ferritin and fibrinogen are themselves inflammatory, creating a positive feedback that exacerbates disease progression. The biophysical correlates we describe may provide novel, inexpensive and useful biomarkers of the therapeutic benefits of successful treatments.

Eryptosis as a marker of Parkinson's disease

A major trend in recent Parkinson's disease (PD) research is the investigation of biological markers that could help in identifying at-risk individuals or to track disease progression and response to therapies. Central to this is the knowledge that inflammation is a known hallmark of PD and of many other degenerative diseases. In the current work, we focus on inflammatory signalling in PD, using a systems approach that allows us to look at the disease in a more holistic way. We discuss cyclooxygenases, prostaglandins, thromboxanes and also iron in PD. These particular signalling molecules are involved in PD pathophysiology, but are also very important in an aberrant coagulation/hematology system. We present and discuss a hypothesis regarding the possible interaction of these aberrant signalling molecules implicated in PD, and suggest that these molecules may affect the erythrocytes of PD patients. This would be observable as changes in the morphology of the RBCs and of PD patients relative to healthy controls. We then show that the RBCs of PD patients are indeed rather dramatically deranged in their morphology, exhibiting eryptosis (a kind of programmed cell death). This morphological indicator may have useful diagnostic and prognostic significance.

Comparative study by computed radiography, histology, and scanning electron microscopy of the articular cartilage of normal goats and in chronic infection with caprine arthritis-encephalitis virus

In the northeast of Brazil, caprine arthritis-encephalitis (CAE) is one of the key reasons for herd productivity decreasing that result in considerable economic losses. A comparative study was carried out using computed radiography (CR), histological analysis (HA), and scanning electronic microscopy (SEM) of the joints of CAE infected and normal goats. Humerus head surface of positive animals presented reduced joint space, increased bone density, and signs of degenerative joint disease (DJD). The carpal joint presented no morphological alterations in CR in any of the animals studied. Tarsus joint was the most affected, characterized by severe DJD, absence of joint space, increased periarticular soft tissue density, edema, and bone sclerosis. Histological analysis showed chronic tissue lesions, complete loss of the surface zone, absence of proteoglycans in the transition and radial zones and destruction of the cartilage surface in the CAE positive animals. Analysis by SEM showed ulcerated lesions with irregular and folded patterns on the joint surface that distinguished the limits between areas of normal and affected cartilage. The morphological study of the joints of normal and CAE positive goats deepened understanding of the alteration in the tissue bioarchitecture of the most affected joints. The SEM finding sustained previous histological reports, similar to those found for rheumatoid arthritis, suggesting that the goat infected with CAE can be considered as a potential model for research in this area.

Carbon monoxide: Anticoagulant or procoagulant?

Within the past decade there have been several investigations attempting to define the impact of exogenous and endogenous carbon monoxide exposure on hemostasis. Critically, two bodies of literature have emerged, with carbon monoxide mediated platelet inhibition cited as a cause of in vitro human and in vitro/in vivo rodent anticoagulation. In contrast, interaction with heme groups associated with fibrinogen, α₂-antiplasmin and plasmin by carbon monoxide has resulted in enhanced coagulation and decreased fibrinolysis in vitro in human and other species, and in vivo in rabbits. Of interest, the ultrastructure of platelet rich plasma thrombi demonstrates an abnormal increase in fine fiber formation and matting that are obtained from humans exposed to carbon monoxide. Further, thrombi obtained from humans and rabbits have very similar ultrastructures, whereas mice and rats have more fine fibers and matting present. In sum, there may be species specific differences with regard to hemostatic response to carbon monoxide. Carbon monoxide may be a Janus-faced molecule, with potential to attenuate or exacerbate thrombophilic disease.

An ultrastructural analysis of platelets, erythrocytes, white blood cells, and fibrin network in systemic lupus erythematosus

The study suggests that patients with systemic lupus erythematosus (SLE) present with distinct inflammatory ultrastructural changes such as platelets blebbing, generation of platelet-derived microparticles, spontaneous formation of massive fibrin network and fusion of the erythrocytes membranes. Lupoid platelets actively interact with other inflammatory cells, particularly with white blood cells (WBCs), and the massive fibrin network facilitates such an interaction. It is possible that the concerted actions of platelets, erythrocytes and WBC, caught in the inflammatory fibrin network, predispose to pro-thrombotic states in patients with SLE.