Demonstration of a novel circulating anti-prostacyclin receptor antibody

Incidence and risk factors of deep vein thrombosis in patients with spinal cord injury: a systematic review with meta-analysis

Background

Spinal cord injury (SCI) is a highly disabling disease with huge public health burden. The complications associated with it, especially deep vein thrombosis (DVT), further aggravate the disability.

Objective

To explore the incidence and risk factors of DVT after SCI, in order to provide guidance for disease prevention in the future.

Methods

A search was performed on PubMed, Web of Science, Embase, and Cochrane database up to November 9, 2022. Literature screening, information extraction and quality evaluation were performed by two researchers. The data was later combined by metaprop and metan commands in STATA 16.0.

Results

A total of 101 articles were included, including 223,221 patients. Meta-analysis showed that the overall incidence of DVT was 9.3% (95% CI: 8.2%-10.6%), and the incidence of DVT in patients with acute and chronic SCI was 10.9% (95% CI: 8.7%-13.2%) and 5.3% (95% CI: 2.2%-9.7%), respectively. The incidence of DVT decreased gradually with the accumulation of publication years and sample size. However, the annual incidence of DVT has increased since 2017. There are 24 kinds of risk factors that may contribute to the formation of DVT, involving multiple aspects of the baseline characteristics of the patient, biochemical indicators, severity of SCI, and comorbidities.

Conclusions

The incidence of DVT after SCI is high and has been gradually increasing in recent years. Moreover, there are numerous risk factors associated with DVT. Comprehensive preventive measures need to be taken as early as possible in the future.

Systematic Review Registration

www.crd.york.ac.uk/prospero, identifier CRD42022377466.

Non-conventional hemostatic risk factors for coronary heart disease in individuals with spinal cord injury

STUDY DESIGN

Review.

OBJECTIVES

In subjects with spinal cord injury (SCI), there is strong evidence for platelet hyperactivity, which may stimulate atherosclerosis and coronary heart disease (CHD). The literature was reviewed.

BACKGROUND

Individuals with SCI develop premature CHD. In addition to the conventional risk factors associated with CHD, there are pathologic hematological factors involved in atherogenesis that are similar to those that have been demonstrated in individuals with diabetes, and these hematological factors might affect individuals with SCI. One such hematological factor, platelet aggregation, is essential for the development of CHD, which results from thrombus formation in the coronary vasculature. Prostacyclin (PGI(2)) is a potent inhibitor of platelet aggregation and is thought to have a beneficial role in inhibiting atherogenesis; therefore, it is possible that individuals with SCI have impaired PGI(2) receptor function.

METHODS

We reviewed the literature by conducting a search using PubMed (1970-2007).

RESULTS

Acute thrombosis is emerging as an important factor in the etiology of CHD and therefore could mediate the risk of CHD in persons with SCI, in addition to previously known risk factors such as hyperlipidemia, hypertension, hyperlipidemia, diabetes mellitus and hyperinsulinemia. Because PGI(2) may retard atherogenesis through its inhibitory effects on platelet function, we discuss the effects of PGI(2) on platelets in persons with SCI in this review.

CONCLUSIONS

Subjects with chronic SCI develop abnormal platelet function, resulting in the production of atherogenic and thrombogenic factors for the following reasons: (1) the PGI(2) and insulin receptors on their platelets are impaired; (2) thrombin generation and platelet-derived growth factor release are elevated; (3) insulin-induced nitric oxide production by platelets is markedly impaired; and (4) a circulating antibody (immunoglobulin G (IgG)) blocks the antithrombotic effect of both insulin and PGI(2) receptors. Thus, this IgG molecule is thought to be one of the pathological mediators of the increased incidence of CHD in individuals with SCI.

Lower-extremity functional electrical stimulation decreases platelet aggregation and blood coagulation in persons with chronic spinal cord injury: a pilot study

BACKGROUND

Individuals with spinal cord injury (SCI) develop premature cardiovascular disease. Regular exercise reduces the incidence and symptoms of cardiovascular disease in able-bodied individuals; these salutary effects of exercise have not been documented in persons with SCI.

OBJECTIVE

To evaluate the effects of functional electrical stimulation leg cycle ergometry (FES-LCE) exercise training on platelet aggregation and blood coagulation in persons with SCI.

PARTICIPANTS

Subjects (n=14) with stable chronic (>1 year) paraplegia (T1-T10) or tetraplegia (C4-C8).

METHODS

Blood samples were collected before and after the first and eighth sessions (2 sessions per week for 4 weeks) of FES exercise.

RESULTS

Platelet aggregation was inhibited by 20% after the first session and by 40% (P < 0.001) after the eighth session. Thrombin activity was unchanged after the first session (10.7 +/- 0.85 s to 10.43 +/- 0.56 s) and decreased after the eighth session (12.5 +/- 1.98 s to 11.1 +/- 1.7 s; P < 0.0003). Antithrombin III activity increased after the first (103.8% +/- 8.9% to 110% +/- 6.9%; P < 0.0008) and eighth sessions (107.8% +/- 12.1% to 120.4% +/- 13.1%; P < 0.0001). Cyclic adenosine monophosphate increased after the first (9.9% + 2.5% to 15.8% +/- 3%; P < 0.001) and eighth sessions (17.8% +/- 4.2% to 36.5% +/- 7.6%; P < 0.0001). After the eighth session, factors V and X increased significantly (88% +/- 27% to 103% +/- 23%, P < 0.0001; 100% +/- 40% to 105% +/- 7%, P < 0.01, respectively); factors VII and VIII and fibrinogen did not change significantly. A significant reduction in platelet activation/aggregation was demonstrated in response to FES-LCE. The decrease in thrombin level was caused by the simultaneous increase in antithrombin activity.

CONCLUSION

These findings provide new insight into the potential protective effects of FES-LCE against the risk of cardiovascular disease.

Effects of oxandrolone, an anabolic steroid, on hemostasis

This study evaluated the short-term effects of oxandrolone, an anabolic androgenic synthetic steroid, on blood coagulation and the hemostatic/fibrinolytic system in healthy individuals. Subjects (n = 14) were administered oxandrolone (10 mg twice daily) for 14 days. Blood was obtained on days 0, 1, 3, 7, 9, 14, and then at day 42 (28 days after discontinuation of the drug). Samples were analyzed for the plasma plasminogen, plasminogen activator inhibitor (PAI-1), fibrinogen, and coagulation factors (II, V, VII, VIII, and X). After 7 days of administration of oxandrolone, the plasma plasminogen level significantly increased [100% +/- 21% to 174% +/- 21% (P < 0.0001)]. PAI-1 was significantly decreased at day 3 [16 +/- 9 to 7 +/- 4 mg/dL (P < 0.01)]. Coagulation factors II and V significantly increased at day 14 [88 +/- 15 to 122 +/- 11 (P < 0.005) and 105 +/- 21 to 179 +/- 36% (P < 0.0001)], respectively. Factor VII level decreased by day 3 [91% +/- 26% to 83% +/- 18%, NS], but after 14 days factor VII level returned to baseline (91% +/- 26% to 93% +/- 19%, NS). The increase of factor VIII level was not significant (111% +/- 64% to 125% +/- 55%, NS). Factor X increased steadily over 14 days of drug treatment [96% +/- 11% to 107% +/- 25%, NS] and after discontinuation, decreased and returned to baseline by day 42 [107% +/- 25% to 89% +/- 25%, NS]. Fibrinogen decreased by 22% +/- 12%, (NS). Administration of oxandrolone, to healthy young men was associated with a significant increase in select blood coagulation factors and plasminogen. These changes create a state of potential hypercoagulability that appears to be counterbalanced by increased fibrinolytic activity to maintain homeostasis.

Circulating heavy chain IgG, a pathological mediator for coronary artery disease, recognizes platelet surface receptors of both prostacyclin and insulin

Although an increased incidence of premature cardiovascular disease has been determined to be the major cause of mortality in subjects with chronic spinal cord injury the identity of the pathophysiological mediators of cardiovascular disease in spinal cord injury remains obscure. Because both insulin and prostacyclin could be important in the prevention of thrombosis, the status of insulin-induced nitric oxide production and the prostacyclin high-affinity receptor interaction in platelets in subjects with spinal cord injury was studied. It was established that the insulin-induced nitric oxide synthesis in platelets from spinal cord-injured subjects was markedly impaired (0.053-0.058, P = 0.37-0.44) compared to (0.062-0.53 microM/10(8) platelets, P < 0.001) due to the presence of a free heavy chain IgG (Mr 47 kDa) in the circulation of subjects with spinal cord injury. This IgG not only blocked insulin receptor binding sites (without affecting dissociation constant of the hormone binding, Kd1 = 2 x 10(-9) M) for the synthesis of nitric oxide but also blocked the prostacyclin receptor interaction in normal platelets. Since the presence of circulating heavy chain of IgG could block the antithrombotic effect of both insulin and prostacyclin, the free heavy chain of the IgG molecule was thought to be one of the pathological mediators for the increased incidence of cardiovascular disease in individual with spinal cord injury. The cross-reactivity of the free heavy chain with two different receptors antigens was thought to be related to the presence of several regions of homology in the amino acid sequence in the insulin and prostacyclin receptor molecules.

Development of platelet inhibition by cAMP during megakaryocytopoiesis

Prostacyclin is a potent inhibitor of agonist-induced Ca2+ increases in platelets, but in the megakaryocytic cell line MEG-01 this inhibition is absent. Using human megakaryocytic cell lines representing different stages in megakaryocyte (Mk) maturation as well as stem cells and immature and mature megakaryocytes, we show that the inhibition by prostacyclin develops at a late maturation stage shortly before platelets are formed. This late appearance is not caused by insufficient cAMP formation or absent protein kinase A (PKA) activity in immature cells. Instead, the appearance of Ca2+ inhibition by prostacyclin is accompanied by a sharp increase in the expression of the catalytic subunit of PKA (PKA-C) but not by changes in the expression of the PKA-regulatory subunits Ialpha/beta, IIalpha, and IIbeta. Overexpression of PKA-C in the megakaryocytic cell line CHRF-288-11 potentiates the Ca2+ inhibition by prostacyclin. Thus, up-regulation of PKA-C appears to be a key step in the development of Ca2+ inhibition by prostacyclin in platelets.

Impaired platelet prostacyclin receptor activity: a monozygotic twin study discordant for spinal cord injury

Coronary artery disease (CAD) has been reported to occur prematurely in individuals with spinal cord injury (SCI). Although persons with SCI have metabolic abnormalities that may predispose them to CAD, other potential aetiologies may also be operative. Increased platelet aggregation, among other factors, initiates thrombus formation at the site of the vessel injury, which may acutely obstruct arterial blood flow. Prostacyclin is known to have a beneficial effect to inhibit platelet aggregation and prevent thrombus formation. Platelets were studied from 12 pairs of monozygotic twins, one co-twin with SCI. Each twin pair had similar patterns of platelet aggregation with adenosine diphosphate (ADP), thrombin or collagen, as well as inhibition of platelet aggregation by prostacyclin (PGE1/I2) and synthesis of cyclic adenosine mono phosphate (AMP) by the prostanoid. However, the twin pairs differed in their response to PGE1/I2 inhibition of platelet-stimulated thrombin generation that was completely inhibited in non-SCI platelets but not in SCI platelets. Scatchard analysis of the binding of 3H-prostaglandin E1, a stable prostacyclin receptor probe, showed the presence of one high-affinity (Kd1=8.1 +/- 2.8 nM; nl=168 +/- 35 sites per platelet) and one low-affinity (Kd2=1.1 +/- 0.22 microM; n2=1772 +/- 220 sites per cell) prostacyclin receptor in normal platelets, whereas in SCI platelets there was a significant loss (P<0.00l) of high-affinity receptor sites (Kd1=6.34 +/- 1.80 nM; n1=42 +/- 11 sites per platelet) with no significant change in the low-affinity receptor sites (Kd2=1.2 +/- 0.23 microM; n2=1860 +/- 412 sites per cell). These discordant platelet findings in identical twin pairs raises the possibility of an environmental aetiology for accelerated CAD in those with SCI. The loss of inhibitory effect of PGI2 on thrombin generation in the twin with SCI appears to be because of loss of platelet high-affinity prostanoid receptors, which may contribute to atherogenesis in individuals with SCI.

Platelet-stimulated thrombin and PDGF are normalized by insulin and Ca2+ channel blockers

Coronary artery disease is accelerated in chronic spinal cord injury (SCI). Because prostacyclin (PGI2) may retard atherogenesis through its inhibitory effects on platelet function, the role of PGI2 on SCI platelets was determined. The SCI platelets were neither hypersensitive to aggregating agonists nor resistant to the inhibitory effect of PGI2, but PGI2 failed to inhibit platelet-stimulated thrombin generation and the release of platelet-derived growth factor (PDGF) in SCI. Because thrombin and PDGF are atherogenic mitogens, the generation of these mitogens was investigated. Both the release of PDGF and thrombin generation in SCI platelets were higher when compared with control (n = 12). Treatment of non-SCI platelets with 100 nM PGE1 (a stable probe of PGI2) inhibited the release of the mitogens by 90% (P < 0.001), with no effect on SCI platelets. Scatchard analysis of prostaglandin E1 (PGE1) binding showed a 70% decrease of PGI2 receptors on the SCI platelet surface. Treatment of SCI platelets with insulin or Ca2+ channel blockers restored the PGI2-receptor number and "normalized" the inhibition of PDGF release and thrombin generation by PGI2.