Anti-Ro/SSA antibodies and cardiac arrhythmias in the adult: facts and hypotheses.

It is well established that the passive trans-placental passage of anti-Ro/SSA antibodies from mother to foetus is associated with the risk to develop an uncommon syndrome named neonatal lupus (NLE), where the congenital heart block represents the most severe clinical feature. Recent evidence demonstrated that also adult heart, classically considered invulnerable to the anti-Ro/SSA antibodies, may represent a target of the arrhythmogenicity of these autoantibodies. In particular, the prolongation of the QTc interval appears the most frequent abnormality observed in adults with circulating anti-Ro/SSA antibodies, with some data suggesting an association with an increased risk of ventricular arrhythmias, also life threatening. Moreover, even though the association between anti-Ro/SSA antibodies and conduction disturbances is undoubtedly less evident in adults than in infants, from the accurate dissection of the literature data the possibility arises that sometimes also the adult cardiac conduction tissue may be affected by such antibodies. The exact arrhythmogenic mechanisms involved in foetus/newborns and adults, respectively, have not been completely clarified as yet. However, increasing evidence suggests that anti-Ro/SSA antibodies may trigger rhythm disturbances through an inhibiting cross-reaction with several cardiac ionic channels, particularly the calcium channels (L-type and T-type), but also the potassium channel hERG, whose different expression and involvement in the cardiac electrophysiology during lifespan might account for the occurrence of age-related differences.

Inhibitory effect of synthetic cannabinoids on cytokine production in rheumatoid fibroblast-like synoviocytes.

OBJECTIVE: To verify whether synthetic cannabinoids (CP55,940 and WIN55,212-2) are able to exert an anti-inflammatory effect on rheumatoid fibroblast-like synoviocytes (FLS) by down-regulating cytokine production, and determine whether this effect could be mediated by CB1/CB2 cannabinoid receptors. METHODS: Interleukin-6 (IL-6) and interleukin-8 (IL-8) were assayed in the supernatant from cultured FLS by ELISA method before and after 3 hours of incubation with CP55,940 (10 microM) and WIN55,212-2 (10 microM). Co-stimulation of cells with the cannabinoid receptor antagonists was performed to evaluate receptor involvement in cytokine modulation. All the experiments were conducted in basal conditions and after 1 hour pre-incubation with 0.1 ng/ml IL-1beta. FLS expression of CB1 and CB2 receptor was studied by Western Blot analyses. RESULTS: Both CP55,940 and WIN55,212-2 induced a potent and significant reduction in IL-6 and IL-8 secretion from IL-1beta. stimulated FLS. Although FLS express CB1 and CB2 receptor, cannabinoid receptor antagonists did not significantly modify the inhibition of cytokines secretion induced by CP55,940 and WIN55,212-2. CONCLUSIONS: In vitro, CP55,940 and WIN55,212-2 exert a potent anti-inflammatory effect on rheumatoid FLS via a non-CB1/CB2 receptor mediated mechanism.

Simvastatin inhibits cytokine production and nuclear factor-kB activation in interleukin 1beta-stimulated synoviocytes from rheumatoid arthritis patients.

OBJECTIVES: Recent studies demonstrated in vivo the effectiveness of statins in reducing the inflammatory response in rheumatic diseases, and still more recently, simvastatin has been reported to inhibit in vitro IL-6 and IL-8 production by unstimulated fibroblast-like-synoviocytes (FLS) from rheumatoid arthritis (RA) patients. However, no data are available on the effect of statins on the production of these cytokines induced by IL-1, which plays a crucial role in joint inflammation in the course of active RA in vivo. METHODS: In 12 RA patients, synovial tissue specimens were taken to obtain cultures of FLS. Cultures were incubated with IL-1 +/- simvastatin (5-50 micromol/l), and IL-6 and IL-8 production was evaluated (ELISA), also following the addition of mevalonate and its isoprenoid derivatives. Moreover, nuclear factor-kB (NF-kB) activation (immunocytochemistry and Western Blot analysis) were also evaluated. RESULTS: Culture incubation with IL-1 produced a dramatic increase (up to 40-fold) in cytokine production with respect to unstimulated cells. Simvastatin significantly inhibited (about 20%) IL-6 and IL-8 production from IL-1-stimulated FLS. This effect was completely reverted by the concomitant incubation with mevalonate or geranylgeraniol (but not farnesol or squalene). Moreover, simvastatin produced a clear-cut inhibition of IL-1-induced NF-kB activation. CONCLUSION: Simvastatin significantly inhibits the production of IL-6 and IL-8 also in IL-1-stimulated FLS, even though to a lesser extent than in unstimulated cells, via a HMG-CoA-reductase block with an interference in prenylation process and NF-kB activation. Our results further support the rationale for the use of statins in the treatment of rheumatoid synovitis.

Hyperhomocysteinemia: a cardiovascular risk factor in autoimmune diseases?

Epidemiological studies conducted over the past 25 years have provided ample support for the association of mild hyperhomocysteinemia (HHcy) with an elevated risk of atherothrombosis. Since autoimmune disorders (AD) are frequently associated with relevant and early signs of atherothrombotic damage not adequately explained by the traditional risk factors involved in the onset of cardiovascular disease (CVD), a large interest has been shown to the putative role of mild HHcy in this setting. On the basis of such considerations, we focused the attention on the relationship between homocysteine (Hcy) and CVD in patients affected with autoimmune diseases, reviewing the most recent literature data and also providing our original experience. Although the large amount of available studies clearly shows that HHcy represents a common finding in patients affected with several autoimmune diseases, the actual role of Hcy in the development of CVD in the course of AD is not clear yet, perhaps, with the only exception of the systemic lupus erythematosus. In the other conditions, the role of Hcy in the pathogenesis of vascular complications is still a matter of debate, as the result of conflicting reports and/or lack of an adequate body of investigation.

Homocysteine enhances cytokine production in cultured synoviocytes from rheumatoid arthritis patients.

OBJECTIVE: Hyperhomocysteinemia is commonly observed in Rheumatoid Arthritis (RA) patients, thus putatively accounting in part for the high rate of cardiovascular events in these subjects. Homocysteine (Hcy) is known to exert a pro-inflammatory effect putatively contributing to the progression of atherosclerotic lesions by cytokine production from several vascular cell-types. In order to evaluate the possibility that Hcy may play a direct pro-inflammatory activity also in the joints of RA patients, we investigated: (i) the joint concentration of Hcy, and (ii) the effect of Hcy on cytokine production by unstimulated and IL-1beta-stimulated human RA cultured synoviocytes. METHODS: In 5 RA and 5 controls subjects, Hcy was measured in the blood and knee synovial fluid, and specimens of synovial tissue were taken to obtain cell cultures. Cultures were incubated with Hcy (10-100 micromol/l) +/- IL-1beta, and IL-6 and IL-8 concentrations were evaluated in the supernatants (ELISA) together with the activation of nuclear factor-kB (NF-kB) (immunocytochemistry). RESULTS: Hcy was present in synovial fluids, with a mean concentration significantly higher in RA patients than in controls (9.0 +/- 1.1 vs 5.9 +/- 1.2 micromol/l). Hcy enhanced IL-6 and IL-8 production in RA synoviocytes only (up to 35%). Moreover, Hcy produced a clear-cut activation of NF-kB in rheumatoid cells only. CONCLUSION: Hcy enhances IL-1-dependent cytokine production by rheumatoid synoviocytes at a concentration measurable in RA joints in vivo. Thus, in RA patients, Hcy may not only represent an important risk factor for the progression of cardiovascular diseases, but it may also contribute to the joint damage.

Simvastatin reduces MMP-3 level in interleukin 1beta stimulated human chondrocyte culture.

OBJECTIVES: Matrix metalloproteinases (MMPs) produced by chondrocytes play a role in the development of cartilage degradation in joint diseases. Moreover, inhibition of MMP secretion by macrophages accumulating in arteriosclerotic plaques would account for the plaque stabilising activity of statins in cardiovascular patients. Recently, simvastatin has been shown to inhibit both developing and established collagen induced arthritis in a murine model. We thus decided to investigate the effect of simvastatin on the production of MMP-3 from cultured interleukin (IL)1 stimulated human chondrocytes. METHODS: Cells from human cartilage, obtained from eight subjects with osteoarthritis undergoing surgery for total hip prostheses, were cultured in the presence of different concentrations of simvastatin (5, 10, and 50 micromol/l) with and without IL1beta (5 ng/ml). MMP-3 level was measured in the culture medium after 48 h of incubation. RESULTS: IL1beta stimulation of chondrocytes increased MMP-3 concentration in the cultures (from 0.69 (0.09) to 1.94 (0.12) ng/microg protein). Incubation with simvastatin was associated with a dose dependent reduction in MMP-3 increase, both in the presence (-15%, -17%, and -26% with 5, 10, and 50 micromol/l, respectively) and in the absence (-32% with 50 micromol/l) of IL1beta. The inhibiting effect of simvastatin was completely reversed by the addition of mevalonate (100 micromol/l) or farnesol (10 micromol/l). CONCLUSIONS: Our data show that simvastatin, by blocking HMGCoA-reductase and interfering in the prenylation processes, is able to inhibit MMP-3 production from cultured human chondrocytes that have been either unstimulated or stimulated with IL1beta, thus suggesting a possible additional mechanism for statins in counteracting chronic joint disease related cartilage damage.

Blunted increase in plasma adenosine levels following dipyridamole stress in dilated cardiomyopathy patients.

BACKGROUND: Heart failure is characterized by chronically increased adenosine levels, which are thought to express a protective anti-heart failure activation of the adenosinergic system. The aim of the study was to assess whether the activation of adenosinergic system in idiopathic dilated cardiomyopathy (IDC) can be mirrored by a blunted increase in plasma adenosine concentration following dipyridamole stress, which accumulates endogenous adenosine. METHODS: Two groups were studied: IDC patients (n = 19, seven women, mean age 60 +/- 12 years) with angiographically confirmed normal coronary arteries and left ventricular ejection fraction <35%; and normal controls (n = 15, six women, mean age 68 +/- 5 years). Plasma adenosine was assessed by high-performance liquid chromatography methods in blood samples from peripheral vein at baseline and 12 min after dipyridamole infusion (0.84 mg kg-1 in 10 min). RESULTS: At baseline, IDC patients showed higher plasma adenosine levels than controls (276 +/- 27 nM L-1 vs. 208 +/- 48 nM L-1, P < 0.001). Following dipyridamole, IDC patients showed lower plasma adenosine levels than controls (322 +/- 56 nM L-1 vs. 732 +/- 250 nM L-1, P < 0.001). The dipyridamole-induced percentage increase in plasma adenosine over baseline was 17% in IDC and 251% in controls (P < 0.001). By individual patient analysis, 18 IDC patients exceeded (over the upper limit) the 95% confidence limits for normal plasma adenosine levels at baseline, and all 19 exceeded (below the lower limit) the 95% confidence limits for postdipyridamole plasma adenosine levels found in normal subjects. CONCLUSION: Patients with IDC have abnormally high baseline adenosine levels and--even more strikingly--blunted plasma adenosine increase following dipyridamole infusion. This is consistent with a chronic activation of the adenosinergic system present in IDC, which can be measured noninvasively in the clinical theatre.

Acute effects of glibenclamide on reactive hyperaemia in the lower limbs in humans.

Three episodes of 1 min ischemia in the lower limbs in humans reduced the metabolic debt repayment (expressed as AUC of reactive hyperaemia) following more prolonged ischemia (666.6+/-86.6 vs 500.0+/-33.5 ml/100 ml). The administration of the ATP-dependent K(+) channel blocker glibenclamide was associated with a significant reduction in the AUC of reactive hyperaemia (666.6+/-86.6 vs 563.1+/-76.6 ml/100 ml), and with the removal of the protective effect produced by 3 episodes of 1 min ischemia (563.1+/-76.6 vs 551.8+/-71.3 ml/100 ml). Plasma level of glibenclamide reached the peak value of 1.295+/-0.15 micromol/l 2 h after drug administration, ranging around the 1 micromol/l concentration in the following 3 hours. Our findings produce indirect evidence that, similarly to the ischemic preconditioning of the heart, the protective effects towards ischemia of brief repeated episodes of sub-maximal occlusion in the peripheral circulation of the lower limbs in humans are mediated by ATP-dependent K(+) channels.

Effects of alprostadil on blood rheology and nucleoside metabolism in patients affected with lower limb chronic ischaemia.

The acute (0.57 microg/kg i.v. in 2 hours) and long-term (0.57 microg/kg i.v. in 2 hours for 5 days over 4 weeks) effects of the PGE1 analogue alprostadil were studied in patients affected with intermittent claudication. Whole Blood Viscosity (WBV), Whole Blood Filterability (WBF), haematocrit (Htc) and fibrinogen plasma concentration, were studied together with P50, 2,3-diphosphoglycerate, and adenosine plasma levels. Moreover, in the long-term study, pain-free (PFWD) and maximal walking distance (MWD) were measured. Single alprostadil infusion induced an improvement in WBV, WBF, and oxygen transport, and an increase in adenosine plasma levels. Long-term alprostadil administration produced a decrease in WBV only, without significant changes in WBF, Htc, fibrinogen, P50, 2,3-diphosphoglycerate, also inducing a significant prolongation of PFWD and MWD. The possibility is suggested that pulse rises in adenosine plasma levels play a role in the effects of chronic alprostadil administration, maybe in a way similar to that observed in the phenomenon of ischaemic preconditioning,

Effects of dipyridamole and adenosine on vasoactive peptides calcitonin gene-related peptide and atrial natriuretic peptide in humans: role of sympathetic activation.

1. It has been observed that dipyridamole (DIP) administration produces equivalent cardiovascular effects at lower systemic adenosine (ADO) plasma concentrations than those obtained with exogenous ADO infusion. This observation led to the identification of DIP for additional 'ischaemia-inducing' mechanisms, possibly based on sympathetic activation. 2. In turn, exogenous ADO administration has proven to elicit a complex neurohumoral response, including an increase in the plasma concentration of catecholamines, associated with augmented levels of the vasoactive peptides calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP). More particularly, increases in CGRP seem to be dependent on sympathetic activation, while changes in ANP do not. 3. In order to clarify some aspects of the activity of DIP on neurohumoral systems, the effects of administration of DIP and ADO on plasma levels of noradrenaline (NA), CGRP and ANP were studied in healthy volunteers. Haemodynamic parameters were also monitored. 4. Infusion of exogenous ADO produced plasma levels of ADO as high as 1893+/-386 nmol/L, together with a significant increase in plasma levels of CGRP, ANP and NA. Similarly, the infusion of DIP produced augmented plasma concentrations of the examined parameters, with a peak plasma ADO concentration of 470+/-49 nmol/L. 5. At a given ADO plasma concentration of 450+/-10 nmol/L, the increase in CGRP and NA levels with DIP infusion was significantly higher than that observed following the infusion of ADO, whereas the increase in the plasma concentration of ANP following DIP infusion was very similar to that seen following ADO infusion. 6. The physiological background of these findings is based on evidence that DIP displays a greater sympathoexcitatory activity than does exogenous ADO and only the increase in plasma CGRP seems to be mediated, although indirectly, by beta-adrenoceptor stimulation. The exact mechanism of DIP-dependent sympathetic activation remains to be elucidated.