Fibrinogen effects on erythrocyte nitric oxide mobilization in presence of acetylcholine

Red Blood Cell-Related Parameters in Rheumatoid Arthritis: Clinical Value and Immunological Significance

Rheumatoid arthritis (RA) is characterized by chronic inflammation and autoimmunity. Moreover, the disease activity, co-morbidities, and prognosis of RA are closely associated with changes in red blood cell (RBC)-related parameters. The role of these parameters in RA has therefore been extensively studied. Accordingly, this article summarizes and analyzes the close relationship of RBC-related parameters such as RBC count, hemoglobin, and RBC distribution width with disease activity, co-morbidities, and prognosis in RA by reviewing the available literature. In addition, given the immunomodulatory functions of RBCs, their surface proteins, contents, and microparticles are involved in the immunomodulatory process during RA. Overall, this review aims to assess the important clinical value and immunological significance of RBCs and their related parameters in the monitoring and management of RA, thus providing a reference for the clinical diagnosis and treatment of RA and the direction for the research on RBC-related immunity.

Attenuation of Thrombin-Mediated Fibrin Formation via Changes in Fibrinogen Conformation Induced by Reaction with S-nitroso-N-acetylpenicillamine, but not S-nitrosoglutathione

Previous work in a 4 h rabbit thrombogenicity model has shown that a nitric oxide- (NO) generating polymer extracorporeal circuits (ECC) with infusion of S-nitroso-N-acetyl-penicillamine (SNAP) preserved platelets eventhough platelets were activated as shown by an increase in the glycoprotein, p-selectin. The platelet preservation mechanism was shown to be due to a changing fibrinogen structure leading to attenuation of platelet aggregation. Understanding the effects that SNAP, another RSNO, S-nitroso-glutathione (GSNO) as well as the non-RSNO, sodium nitroprusside (SNP), may have on human fibrinogen polymerization, this in vitro study evaluated the released NO effects on the thrombin-mediated fibrin formation and fibrinogen structure. Thrombin-induced fibrin formation at 300 μM SNAP (50 + 11% of baseline) was significantly reduced compared to SNAP's parent, N-acetyl-penicillamine (NAP) (95 + 13%) after 1 h of RSNO exposure. GSNO, its parent, glutathione (GSH) and 1000 ppm NO gas did not attenuate the thrombin-mediated fibrin formation. SNAP, NAP and SNP exposure for 1 h, however, did not decrease thrombin activity by directly inhibiting thrombin itself. Changes in fibrinogen conformation as measured by intrinsic tryptophan fluorescence significantly decreased in the 300 μM SNAP (38057 + 1196 mean fluorescence intensity (MFI) and SNP (368617 + 541 MFI) groups versus the NAP control (47937 + 1196 MFI). However, infused 1000 ppm NO gas had no direct effect on the ITF after 1 h incubation at 37°C. High performance liquid chromatography (HPLC) showed that fibrinogen degradation by 0.03 U/ml thrombin was concentration-dependently reduced after 1 h with SNAP but not with NAP or SNP. Western blotting showed RSNOs, SNAP, NAP and the non-RSNO, SNP-incubated fibrinogen solutions showed that the percent level of the Aγ dimer to total Aγ dimer + γ monomer was significantly reduced in the case of the SNAP group when compared to SNP group. These results suggest that NO donors such as SNAP and SNP induce fibrinogen conformational changes by potentially nitrosating fibrinogen tyrosine residues. These NO-mediated fibrinogen changes induced via NO donors may provide another mechanism of NO for improving thromboresistance in ECC.

Nitric oxide in red blood cell adaptation to hypoxia

Nitric oxide (NO) appears to be involved in virtually every aspect of cardiovascular biology. Most attention has been focused on the role of endothelial-derived NO in basal blood flow regulation by relaxing vascular smooth muscle; however, it is now known that NO derived from red blood cells (RBCs) plays a fundamental role in vascular homeostasis by enhancing oxygen (O2) release at the cellular and physiological level. Hypoxia is an often seen problem in diverse conditions; systemic adaptations to hypoxia permit people to adjust to the hypoxic environment at high altitudes and to disease processes. In addition to the cardiopulmonary and hematologic adaptations that support systemic O2 delivery in hypoxia, RBCs assist through newly described NO-based mechanisms, in line with their vital role in O2 transport and delivery. Furthermore, to increase the local blood flow in proportion to metabolic demand, NO regulates membrane mechanical properties thereby modulating RBC deformability and O2 carrying-releasing function. In this review article, we focus on the effect of NO bioactivity on RBC-based mechanisms that regulate blood flow and RBC deformability. RBC adaptations to hypoxia are summarized, with particular attention to NO-dependent S-nitrosylation of membrane proteins and hemoglobin (S-nitrosohemoglobin). The NO/S-nitrosylation/RBC vasoregulatory cascade contributes fundamentally to the molecular understanding of the role of NO in human adaptation to hypoxia and may inform novel therapeutic strategies.

Human Erythrocyte Acetylcholinesterase in Health and Disease

The biochemical properties of erythrocyte or human red blood cell (RBC) membrane acetylcholinesterase (AChE) and its applications on laboratory class and on research are reviewed. Evidence of the biochemical and the pathophysiological properties like the association between the RBC AChE enzyme activity and the clinical and biophysical parameters implicated in several diseases are overviewed, and the achievement of RBC AChE as a biomarker and as a prognostic factor are presented. Beyond its function as an enzyme, a special focus is highlighted in this review for a new function of the RBC AChE, namely a component of the signal transduction pathway of nitric oxide.

Identification of erythrocyte biomarkers in amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease of the motor system. It has been hypothesised that red blood cells (RBCs) may be involved in the disease process by the release of damaging molecules.

OBJECTIVE

The aim of this ex vivo study is to compare RBCs biochemical and hemorheological parameters between ALS patients and healthy donors to identify novel biomarkers of the ALS disease.

METHODS

We included 82 ALS patients and 40 gender age-matched healthy donors. We performed quantification of erythrocyte aggregation and deformability, nitric oxide (NO) efflux from RBCs, acetylcholinesterase (AChE) enzyme activity and intraerythrocytic concentration of nitrite, nitrate and S-nitrosogluthatione (GSNO).

RESULTS

Erythrocyte deformability and AChE activity were increased in patients with ALS in comparison to healthy donors. NO efflux from RBCs and concentration of intraerythrocytic nitrite were lower in ALS patients. In patients, we found that for higher NO range of values the respiratory function is worse and that for higher AChE range of values the RBCs nitrite content increase.

CONCLUSION

The results of the present study indicate that NO efflux from RBCs and RBCs AChE should be further explored as potential biomarkers for ALS.

Cholinesterase of rats experimentally infected by Cryptococcus neoformans: Relationship between inflammatory response and pathological findings

The aim of this study was to assess the role of the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) as biomarkers of inflammation and tissue injury on rats experimentally infected by Cryptococcus neoformans. For this purpose, 20 male rats were divided into two groups: 10 animals representing the uninfected control group (Group A) and 10 C. neoformans var. grubii infected animals (Group B). Blood and brain samples were collected on days 10 (A10 and B10), and 30 (A30 and B30) post-infection (PI) for hematological analyses; AChE (in lymphocytes and brain) and seric BChE activity; interleukins (IL-1, IL-6, and IL-10); nitrite/nitrate (NOx) levels; and markers of protein oxidation (AOPP) and lipid peroxidation (TBARS). As a result, when animals of Group A were compared to animals of Group B, it was observed leukocytosis (P<0.05) on day 10 PI; AChE activity increase (P<0.05) in lymphocytes (day 30 PI) and in brain (days 10 and 30 PI); BChE activity decrease (P<0.05) on day 10 PI; IL-1 and IL-6 increase (P<0.01) in both periods, while IL-10 had reduced levels (P<0.01) in the same periods; NOx levels increased (P<0.05) significantly on days 10 and 30 PI, while AOPP and TBARS levels increased significantly on day 30 PI; as well as pneumonia on infected rats. Therefore, based on the results obtained, it was possible to conclude that AChE and BChE behavior lead to a proinflammatory reaction evidenced by the enhancement of IL-1, IL-6, and NOx throughout the experiment associated with reduction on IL-10 levels, and cellular damage.

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.

Application of a nitric oxide sensor in biomedicine

In the present study, we describe the biochemical properties and effects of nitric oxide (NO) in intact and dysfunctional arterial and venous endothelium. Application of the NO electrochemical sensor in vivo and in vitro in erythrocytes of healthy subjects and patients with vascular disease are reviewed. The electrochemical NO sensor device applied to human umbilical venous endothelial cells (HUVECs) and the description of others NO types of sensors are also mentioned.