Platelets: emerging facilitators of cellular crosstalk in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease in which a variety of circulating pro-inflammatory cells and dysregulated molecules are involved in disease aetiology and progression. Platelets are an important cellular element in the circulation that can bind several dysregulated molecules (such as collagen, thrombin and fibrinogen) that are present both in the synovium and the circulation of patients with RA. Platelets not only respond to dysregulated molecules in their environment but also transport and express their own inflammatory mediators, and serve as regulators at the boundary between haemostasis and immunity. Activated platelets also produce microparticles, which further convey signalling molecules and receptors to the synovium and circulation, thereby positioning these platelet-derived particles as strategic regulators of inflammation. These diverse functions come together to make platelets facilitators of cellular crosstalk in RA. Thus, the receptor functions, ligand binding potential and dysregulated signalling pathways in platelets are becoming increasingly important for treatment in RA. This Review aims to highlight the role of platelets in RA and the need to closely examine platelets as health indicators when designing effective pharmaceutical targets in this disease.

Characterizing pathology in erythrocytes using morphological and biophysical membrane properties: Relation to impaired hemorheology and cardiovascular function in rheumatoid arthritis.

The inflammatory burden of the complex rheumatoid arthritis (RA) disease affects several organ-systems, including rheological properties of blood and its formed elements. Red blood cells (RBCs) are constantly exposed to circulating dysregulated inflammatory molecules that are co-transported within the vasculature; and their membranes may be particularly vulnerable to the accompanying oxidative stress. In the current study, we investigate biophysical and ultrastructural characteristics of RBCs obtained from a cohort of patients using atomic force microscopy (AFM), scanning electron microscopy (SEM) and confocal microscopy (CM). Statistical analyses of AFM data showed that RA RBCs possessed significantly reduced membrane elasticity relative to that of RBCs from healthy individuals (P-value <0.0001). SEM imaging of RA RBCs revealed increased anisocytes and poikilocytes. Poikilocytes included knizocytes, stomatocytes, dacryocytes, irregularly contracted cells, and knot cells. CM imaging of several RA RBCs, spectrin, and band 3 protein networks portrayed the similar morphological profiles. Analyses of CM images confirmed changes to distribution of band-3 skeletal protein, a protein critical for gaseous exchange functions of the RBC and preventing membrane surface loss. Decreased membrane deformability impairs the RBC's capacity to adequately adapt its shape to navigate blood vessels, especially microvasculature, and this decrease is also reflected in the cell's morphology. Changes to morphology and deformability may also indicate loss of functional domains and/or pathological protein and lipid associations. These findings suggest that RA disease and/or its concomitant factors impact on the RBC and its membrane integrity with potential for exacerbating pathological cellular function, hemorheology, and cardiovascular function.

Major involvement of bacterial components in rheumatoid arthritis and its accompanying oxidative stress, systemic inflammation and hypercoagulability.

We review the evidence that infectious agents, including those that become dormant within the host, have a major role to play in much of the etiology of rheumatoid arthritis and the inflammation that is its hallmark. This occurs in particular because they can produce cross-reactive (auto-)antigens, as well as potent inflammagens such as lipopolysaccharide that can themselves catalyze further inflammagenesis, including via ß-amyloid formation. A series of observables coexist in many chronic, inflammatory diseases as well as rheumatoid arthritis. They include iron dysregulation, hypercoagulability, anomalous morphologies of host erythrocytes, and microparticle formation. Iron dysregulation may be responsible for the periodic regrowth and resuscitation of the dormant bacteria, with concomitant inflammagen production. The present systems biology analysis benefits from the philosophical idea of "coherence," that reflects the principle that if a series of ostensibly unrelated findings are brought together into a self-consistent narrative, that narrative is thereby strengthened. As such, we provide a coherent and testable narrative for the major involvement of (often dormant) bacteria in rheumatoid arthritis.

Erythrocytes and their role as health indicator: Using structure in a patient-orientated precision medicine approach.

The relevance of erythrocyte light microscopy analysis (a well-known haematological method) is under the spotlight, however there is a place for innovative electron microscopy, (together with biochemical markers) in a pathology laboratory. Inflammation is a key indicator of the health status and erythrocytes are extremely sensitive to oxidative stress or cytokine upregulation, which typically accompany systemic inflammation in most diseases. They are probably the most adaptable cells, and due to their short lifespan, may form a vital indicator of health, and could play a central part in tracking disease and treatment. As the NIH is proposing a precision medicine approach and because individualised medicine should form an essential part in diagnosis and treatment, biophysical combined with biochemical analysis of erythrocytes may be a novel method to track the inflammatory status before and after treatment. This will allow a fully individualised patient orientated precision medicine approach, where one-medication-regime-fits-all is no longer appropriate.

Rheumatoid Arthritis: Notable Biomarkers Linking to Chronic Systemic Conditions and Cancer.

Adult rheumatoid arthritis (RA) is an autoimmune disorder affecting joints and frequently characterised by initial local and later systemic inflammation. Researchers have, for many years, traced its cause to diverse genetic, environmental and especially immunological responses that work against the body's own cells and tissues. Investigation into several of these biomarkers reveals interconnections that exist between multiple factors, which ultimately lead to specific pathologies. The goal of this paper is to highlight connections present between the major biological players long identified by researchers including more recently uncovered biomarkers in the RA repertoire and some of the pathophysiologies typically affiliated with the disease. Biomarkers reviewed, and becoming more clearly defined for RA include genetic, cytokines like tumor-necrosis factor-α (TNF-α), lymphocytes, nuclear antigens, antibodies to citrullinated peptides (anti-CPs), acute-phase proteins (APPs), microRNA, S100 proteins, platelets and erythrocytes. Some of the disease manifestations that have been connected are bone erosion, diabetes, metabolic syndrome, anemia, synovitis, felty's syndrome, extra-articular manifestations (EAMs) such as atherosclerosis, rheumatoid nodules and cardiovascular (CV) events. Several RA markers associated with malignancy have been identified in literature although there is insufficient evidence of cancer in patients. Due to the complex nature of the disease, the appearance of symptoms and markers vary amongst individuals and the connections may manifest only in part. This manuscript addresses defining factors relevant to rapid identification of pathological influences these biomolecules could exert and to the management of the disease. Each of these biological players may have its place in connecting to symptomatic pathologies and help to highlight potential targets for therapy.

Platelet and red blood cell interactions and their role in rheumatoid arthritis.

Cytokines, lymphocytes, platelets and several biomolecules have long been implicated in the pathology of rheumatoid arthritis (RA), and the influences of antibody production and tagging, and cytokine, chemokine and enzyme production at specific rheumatoid joints were thought to be exclusive to the advancement of disease parameters. Another role player in RA is red blood cells (RBCs) which, of late, have been found to be involved in RA pathobiology, as there is a positive correlation between RBC counts and joint pathology, as well as with inflammatory biomarkers in the disease. There is also an association between RBC distribution width and the incidence of myocardial infarction amongst RA patients, and there is a change in the lipid distribution within RBC membranes. Of late, certain RBC-associated factors with previously obscure roles and cell-derived particles thought to be inconsequential to the other constituents of plasma were found to be active biomolecular players. Several of these have been discovered to be present in or originating from RBCs. Their influences have been shown to involve in membrane dynamics that cause structural and functional changes in both platelets and RBCs. RBC-derived microparticles are emerging entities found to play direct roles in immunomodulation via interactions with other plasma cells. These correlations highlight the direct influences of RBCs on exacerbating RA pathology. This review will attempt to shed more light on how RBCs, in the true inflammatory milieu of RA, are playing an even greater role than previously assumed.