Joana R. Batuca

Vascular Abnormalities, Paraoxonase Activity, and Dysfunctional HDL in Primary Antiphospholipid Syndrome

CONTEXT Accelerated atherosclerosis has been described in antiphospholipid syndrome, but the vascular abnormalities and the underlying mechanisms remain unclear. OBJECTIVES To compare vascular structure and function in patients with positive antiphospholipid antibodies (aPL) with controls and to assess their relationship with paraoxonase activity. DESIGN, SETTING, AND PARTICIPANTS A cross-sectional study of 77 women with positive antiphospholipid antibodies from a lupus outpatient clinic in London, England (90% of the eligible population) and 77 controls matched on frequency basis for age and cardiovascular risk factors between June 2006 and April 2009. Carotid intima media thickness (CIMT), flow-mediated dilatation, pulse wave velocity, and paraoxonase activity were measured in all patients. Anti-inflammatory and antioxidant properties of high-density lipoprotein (HDL) were examined. MAIN OUTCOME MEASURES CIMT, pulse wave velocity, flow-mediated dilatation, and paraoxonase. RESULTS Women with aPL had greater CIMT and pulse wave velocity compared with controls (mean [SD], 0.75 [0.16] vs 0.64 [0.09] mm; 95% confidence interval [CI], -0.14 to -0.06; P < .001; and 9.2 [1.6] vs 8.5 [1.8] m/s; 95% CI, -1.14 to -0.06; P = .04) and lower flow-mediated dilatation (6.2% [4.1%] vs 9.6% [4.2%]; 95% CI, 2.02%-4.69%; P < .001). Paraoxonase activity was lower in women with aPL vs controls (median [interquartile range], 91.2 [64.3-105.1] vs 103.0 [80.5-111.5] micromol p-nitrophenol/L/serum/min; 95% CI, 0.004-0.007; P = .005) and was inversely associated with CIMT and pulse wave velocity in women with aPL (standardized beta coefficient = -0.4 and -0.3, respectively; P < .05 for both), but not in the control group. High-density lipoprotein from women with aPL inhibited endothelial nitric oxide production in human aortic endothelial cells, in contrast with controls. The beneficial effects of HDL from women with aPL on vascular cell adhesion molecule 1 expression, superoxide production, and monocyte adhesion following activation of human aortic endothelial cells were largely blunted. CONCLUSIONS Compared with controls, women with aPL had greater functional and structural arterial abnormalities, which were associated with lower activity of paraoxonase. In patients with aPL, HDL reduced nitric oxide bioavailability and had impaired anti-inflammatory and antioxidant properties.

Subclinical atherosclerosis in primary antiphospholipid syndrome

Abstract:  To test the atherosclerosis hypothesis in primary antiphospholipid syndrome (PAPS) we measured intima media thickness (IMT) of carotid arteries and other cardiovascular risk factors in 44 patients with PAPS (mean age 35 ± 12 years), in 25 patients with inherited thrombophilia (mean age 40 ± 10 years), and in 34 normal controls (mean age 38 ± 11 years). The frequency of smoking, hypertension, and dyslipidemia was similar across groups. IMT was almost similar across groups at age groups below 40 years but IMT was greater in PAPS than controls at the common carotid (P= 0.01), at the bifurcation (P= 0.003), and at the internal carotid (P= 0.005) in the age group over 40 years. Atherosclerosis is a possibility in PAPS patients in their fourth decade of life or older.

Primary antiphospholipid syndrome: a low-grade auto-inflammatory disease?

OBJECTIVE To test the inflammation and immune activation hypothesis in primary thrombotic APS (PAPS) and to identify clinical and laboratory factors related to inflammation and immune activation. METHODS PAPS (n = 41) patients were compared with patients with inherited thrombophilia (IT, n = 44) and controls (CTR, n = 39). IgG aCL, IgG anti-beta2-glycoprotein I (beta(2)GPI), high-sensitivity CRP (hs-CRP), serum amyloid A (SAA), CRP bound to oxidized low-density lipoprotein-beta(2)GPI complex (CRP-oxLDL-beta(2)GPI) (as inflammatory markers) neopterin (NPT), soluble CD14 (sCD14) (as immune activation markers) were measured by ELISA. RESULTS After correction for confounders, PAPS showed higher plasma levels of hs-CRP (P = 0.0004), SAA (P < 0.01), CRP-oxLDL-beta(2)GPI (P = 0.0004), NPT (P < 0.0001) and sCD14 (P = 0.007) than IT and CTR. Two regression models were applied to the PAPS group: in the first, IgG aCL and IgG beta(2)GPI were included amongst the independent variables and in the second they were excluded. In the first model, SAA (as the dependent variable) independently related to thrombosis number (P = 0.003); NPT (as the dependent variable) independently related to thrombosis type (arterial, P = 0.03) and number (P = 0.04); sCD14 (as the dependent variable) independently related to IgG beta(2)GPI (P = 0.0001), age (0.001) and arterial thrombosis (P = 0.01); CRP-oxLDL-beta(2)GPI (as the dependent variable) independently related to IgG beta(2)GPI (P = 0.0001). In the second model, sCD14 and NPT independently related to each other (P = 0.002) (this was noted also in the IT group, P < 0.0001) and CRP-oxLDL-beta(2)GPI independently predicted SAA (P = 0.002). CONCLUSION Low-grade inflammation and immune activation occur in thrombotic PAPS and relate to clinical features and aPL levels.

An antagonistic interaction between A2B adenosine and D2 dopamine receptors modulates the function of rat carotid body chemoreceptor cells

We have previously demonstrated that adenosine controls the release of catecholamines (CA) from carotid body (CB) acting on A2B receptors. Here, we have tested the hypothesis that the control is exerted via an interaction between adenosine A2B and dopamine D2 receptors present in chemoreceptor cells. Experiments were performed in vitro in CB from 3 months rats. The effect of A2B adenosine and D2 dopamine agonists and antagonists applied alone or in combination were studied on basal (20%O2) and hypoxia (10%O2)‐evoked release of CA and cAMP content of CB. We have found that adenosine A2 agonists and D2 antagonists dose‐dependently increased basal and evoked release CA from the CB while A2 antagonists and D2 agonists had an inhibitory action. The existence of A2B‐D2 receptor interaction was established because the inhibitory action of A2 antagonists was abolished by D2 antagonists, and the stimulatory action of A2 agonists was abolished by D2 agonists. Further, A2 agonists increased and D2 agonist decreased cAMP content in the CB; their co‐application eliminated the response. The present results provide direct pharmacological evidence that an antagonistic interaction between A2B adenosine and D2 dopamine receptors exist in rat CB and would explain the dopamine‐adenosine interactions on ventilation previously observed.

Clinical relevance of nitric oxide metabolites and nitrative stress in thrombotic primary antiphospholipid syndrome.

Objective. To assess the role of nitrite (NO2−), nitrate (NO3−), and nitrative stress in thrombotic primary antiphospholipid syndrome (PAPS). Methods. We investigated 46 patients with PAPS: 21 asymptomatic but persistent carriers of antiphospholipid antibodies (PCaPL), 38 patients with inherited thrombophilia (IT), 33 patients with systemic lupus erythematosus (SLE), and 29 healthy controls (CTR). IgG anticardiolipin (aCL), IgG anti-beta2-glycoprotein I (anti-ß2-GPI), IgG anti-high density lipoprotein (aHDL), IgG anti-apolipoprotein A-I (aApoA-I), crude nitrotyrosine (NT) (an indicator of nitrative stress), and high sensitivity C-reactive protein (CRP) were measured by immunoassays. Plasma nitrite (NO2−), nitrate (NO3−), and total antioxidant capacity (TAC) were measured by colorimetric spectroscopic assays. Results. Average plasma NO2− was lower in PAPS, PCaPL, and IT (p < 0.0001); average NO3− was highest in SLE (p < 0.0001), whereas average NT was higher in PAPS and SLE (p = 0.01). In thrombotic PAPS, IgG aCL titer and number of vascular occlusions negatively predicted NO2− (p = 0.03 and p = 0.001, respectively), whereas arterial occlusions and smoking positively predicted NO3− (p = 0.05 and p = 0.005), and CRP positively predicted NT (p = 0.004). In the PCaPL group IgG aCL negatively predicted NO3− (p = 0.03). In the SLE group IgG aCL negatively predicted NO2− (p = 0.03) and NO3− (p = 0.02). Conclusion. PAPS is characterized by decreased NO2− in relation to type and number of vascular occlusions and to aPL titers. Nitrative stress and low grade inflammation are linked phenomena in PAPS and may have implications for thrombosis and atherosclerosis.

Carotid body function in aged rats: responses to hypoxia, ischemia, dopamine, and adenosine

The carotid body (CB) is the main arterial chemoreceptor with a low threshold to hypoxia. CB activity is augmented by A2-adenosine receptors stimulation and attenuated by D2-dopamine receptors. The effect of aging on ventilatory responses mediated by the CB to hypoxia, ischemia, and to adenosine and dopamine administration is almost unknown. This study aims to investigate the ventilatory response to ischemia and to adenosine, dopamine, and their antagonists in old rats, as well as the effect of hypoxia on adenosine 3′,5′-cyclic monophosphate (cAMP) accumulation in the aged CB. In vivo experiments were performed on young and aged rats anesthetized with pentobarbitone and breathing spontaneously. CB ischemia was induced by bilateral common carotid occlusions. cAMP content was measured in CB incubated with different oxygen concentrations. Hyperoxia caused a decrease in cAMP in the CB at all ages, but no differences were found between normoxia and hypoxia or between young and old animals. The endogenous dopaminergic inhibitory tonus is slightly reduced. However, both the ventilation decrease caused by exogenous dopamine and the increase mediated by A2A-adenosine receptors are not impaired in aged animals. The bradycardia induced by adenosine is attenuated in old rats. The CB’s peripheral control of ventilation is preserved during aging. Concerns have also arisen regarding the clinical usage of adenosine to revert supraventricular tachycardia and the use of dopamine in critical care situations involving elderly people.

Acute hypoxia modifies cAMP levels induced by inhibitors of phosphodiesterase-4 in rat carotid bodies, carotid arteries and superior cervical ganglia

Background and purpose:  Phosphodiesterase (PDE) inhibitors are useful to treat hypoxia‐related diseases and are used in experiments studying the effects of oxygen on 3′‐5′‐cyclic adenosine monophosphate (cAMP) production. We studied the effects of acute hypoxia on cAMP accumulation induced by PDE inhibitors in oxygen‐specific chemosensors, the carotid bodies (CBs) and in non‐chemosensitive CB‐related structures: carotid arteries (CAs) and superior cervical ganglia (SCG).

Contribution of Dopamine D2 Receptors for the cAMP Levels at the Carotid Body

There is a general consensus that the effects of dopamine at the carotid body (CB) are mediated by activation of both D1and D2 receptor subtypes (Gonzalez et ai. 1994). D1- and D2-like receptors have been defined traditionally by their opposing effects on the enzyme adenylate cyclase (AC), with D1-like (D1 and D5) receptors positively coupled to this enzyme, whereas D2-like (D2 D3 and D4) are either negatively coupled or uncoupled to this effector (Missale et al. 1998). Excitatory effects of exogenous dopamine (1 and 10 μM) on cyclic adenosine 3’,5’-monophosphate (cAMP) production have been described at the rabbit CB equilibrated with hyperoxia and attributed to the activation of D1 receptors (Perez-Garcia et al. 1990; Almaraz et al. 1991). The present work was undertaken to investigate the contribution of D2 receptors to cAMP production at the rat CB in hyperoxia, normoxia and hypoxia.

Humoral Mechanisms of Atherogenesis

The concept that atherosclerosis is an autoimmune disease is no longer controversial. Attention has been paid to cellular immune response, but current research is now focused on the humoral component of this complex disease. Heat shock proteins, oxidized low‐density lipoproteins, β2‐glycoprotein 1, cardiolipins, and, more recently, high‐density lipoproteins have been considered to be autoantigens that play a part in atherogenesis. The characterization and understanding of the mechanisms associated with the presence of these antigens and their respective autoantibodies might contribute to elucidating the atherosclerotic process. In the near future, immune modulation might constitute a very effective therapy of atherosclerosis.

Effects of Atorvastatin on Atherosclerosis and Atherogenesis in Systemic Lupus Erythematosus: A Pilot Study

Objective. The effect of statins on atherogenesis in systemic lupus erythematosus (SLE) is poorly known. To inform a wider trial we performed a pilot study evaluating the intima-media thickness of the common carotid artery (CIMT) and some oxidative [beta-2-glycoprotein-1 complexed with oxidised low density lipoprotein (2GPIoxLDL)], metabolic [paraoxonase (PON), nitrate (), nitrite () and nitrotyrosine (NT)], inflammatory [C-reactive protein (CRP) and serum amyloid A (SAA)], and lipid markers before and after 1 year of treatment with 40 mg of oral atorvastatin (AT). Methods. Randomised, double blind, placebo controlled pilot study on consecutive SLE patients: 17 SLE patients were randomised into the AT arm and 20 into the placebo arm. CIMT was measured by high-resolution sonography, PONa by a spectrophotometric method, and by a colorimetric assay and oxLDL-2GPI, NT, CRP, and SAA by Elisa. Results. After correction for age and disease duration oxLDL-2GPI decreased by 27% () and PON/HDL ratio increased by 12% () but CIMT did not change. Conclusion. This pilot study revealed a decrease of oxLDL-2GPI (oxidant marker) and an increase of PON/HDL ratio (antioxidant activity) after AT indicating a favourable effect of the drug on atherogenic pathways that should be explored on larger trials.