M. Arquati

Regulation of histamine release from human basophil leucocytes: role of H1, H2 and H3 receptors

A novel class of histamine receptors (H3, controlling histamine synthesis and release, was described in rat and human brain and peripheral nerve endings. The present study was undertaken to evaluate whether H3, receptors contribute to the regulation of histamine release from human basophils. Basophil leucocytes were incubated with a H., antagonist (thioperamide; concentrations ranging from 1 nM to 10 μM) or with a H3 agonist ((R)αmethyl‐histamine; concentrations ranging from I to 100 μM), and subsequently were stimulated with optimal doses of anti‐IgE and formyl‐methionyl‐leueyl‐phenyl‐alanine (f‐met peptide). No significant modifications of histamine release were observed after incubation either with the H3 agonist or with the H3 antagonist. By contrast, a H3 antagonist (cimetidine; concentrations ranging from 1 to 100 μM) exerted a dose‐dependent enhancing effect on anti‐IgE‐ and, to a lesser extent, on f‐met peptide‐induced histamine release. A H, antihistamine (chlorpheniramine; concentrations ranging from 100 nM to 1μM), at the highest concentration employed, displayed an inhibitory activity on IgE‐dependent and IgE‐independent histamine release. Exogenous histamine was shown to exert a dose‐dependent inhibitory effect on two‐staged anti‐IgE‐induced histamine release. Taken as a whole, these results suggest that H3 receptors are not involved in the regulation of histamine release from human basophils; by contrast, H2 receptors participate in controlling histamine release from human basophils, as previously demonstrated by other authors.

High prevalence of splenic marginal zone lymphoma among patients with acquired C1 inhibtor deficiency.

Marginal zone lymphoma represents about 10% of all non‐Hodgkin lymphomas (NHLs). 33% of patients with acquired angioedema (AAE) due to acquired C1‐inhibitor (C1‐INH) deficiency (C1‐INH‐AAE) have or will develop NHLs. C1‐INH‐AAE is a rare condition. We report the follow‐up of 72 C1‐INH‐AAE patients, followed for a median of 15 years (range 1–24). Median age was 71 (range 64–79) years; median age at onset of angioedema symptoms was 57·5 (range 50–66) years and it was 63 [range 45–80) years at diagnosis]. Twenty patients were diagnosed with low‐grade non‐follicular B‐cell lymphomas (75% were splenic MZL), one with follicular and three with high‐grade lymphomas (two diffuse large B‐cell lymphomas and one mantle cell lymphoma). Fifteen NHLs were diagnosed at onset of AAE or thereafter (3 months to 7 years), eight had already been diagnosed at onset of angioedema. Two of 24 patients remain on watchful wait. Thirthen of 24 received chemotherapy, two received rituximab. Three underwent splenectomy. All 18 patients receiving therapy for NHL experienced post‐treatment reduction in AAE symptoms. Our study suggests that clonal B‐cell proliferation is the pathology underlying AAE leading to production of C1‐INH‐neutralizing autoantibodies and to NHLs. The post‐germinal centre origin of NHL suggests that immune stimulation may contribute to lymphomagenesis.

Receptor-Operated, but Not Voltage-Operated, Calcium Channels Are Involved in Basophil Leucocyte Activation and Histamine Release

Transmembrane calcium flux is a critical step in basophil and mast cell activation and subsequent histamine release. This calcium flux is likely to take place through specialized membrane ion channels. Two types of calcium channels have been described so far: the first type is voltage operated and the second type is receptor operated. Depolarization of cell membrane by K+-rich solutions is followed by voltage-operated channel opening in excitable cells, such as smooth muscle cells. We evaluated whether high K+ extracellular concentrations can trigger basophil activation and histamine release. We found that human basophil leucocytes, showing a normal response to activating signals, such as anti-IgE antiserum and formylmethionine peptide, release no histamine when exposed to K+-rich media, alone or in combination with the K+ carrier valinomycin. These results are consistent with there being receptor-operated, but not voltage-operated, calcium channels in the basophil leucocyte plasma membrane.

Differential Effect of Hypertonicity on FMLP-, Anti-IgE- and Ca2+ Ionophore A23187-Induced Histamine Release from Human Basophil Leukocytes

Effects of different extracellular Na+ and K+ concentrations (respectively, 135, 155, 220, 260 mM NaCl, and 2.7, 20, 50, 100 mM KCl) on IgE-dependent and IgE-independent histamine release from human basophils were examined. High extracellular Na+ and K+ concentrations were shown to reduce N-formyl-methionyl-leucyl-phenyl-alanine- (FMLP), but not anti-IgE- or Ca2+ ionophore A23187-induced histamine release. A high extracellular Ca2+ (7.2 mM CaCl2) concentration increased basophil response to anti-IgE and FMLP. The enhancement of FMLP- but not of anti-IgE-induced histamine release was antagonized by high extracellular Na+ and K+ concentrations. When leukocytes were suspended in isotonic choline chloride solutions (choline is a nonpermeant monovalent cation), an enhancement of anti-IgE- and FMLP-induced histamine release was observed. This suggests that monovalent cations, namely Na+ ions, at physiological concentrations, downregulate histamine release from human basophils. At high choline chloride concentrations, FMLP-, but not anti-IgE-induced histamine release was inhibited. Thus, the reduction of FMLP-evoked histamine secretion from human basophils seems to be due to hypertonicity and not to the type of monovalent cation, either permeant or nonpermeant, contained in extracellular milieu. The different effects of a hypertonic solution on anti-IgE and FMLP-induced histamine release are probably related to the different cell activation pathways triggered by the two stimuli.

Ionic regulation of human basophil releasability. I. Inhibitory effect of copper

The effects of copper (CuSO4 and CuCl2) onin vitro histamine release from human basophils stimulated by anti-IgE and Ca2+ ionophore A23187 were evaluated. Both CuSO4 and CuCl2 caused a dose-related inhibition of histamine release, which was more pronounced on anti-IgE-than on Ca2+ ionophore-induced histamine release. The concentration which produced 50% inhibition of anti-IgE-induced histamine release was 1.3 μM for CuSO4 and 1.5 μM for CuCl2; the maximal inhibition of Ca2+ ionophore-induced histamine release was 33% for CuCl2 (4 μM) and 51% for CuSO4 (16 μM). The inhibitory effect on anti-IgE-induced histamine release persisted also when extracellular Cu2+ was removed by cell washing before IgE-induced histamine release persisted also when extracellular Cu2+ was removed by cell washing before stimulation, whereas no inhibition of Ca2+ ionophore-induced histamine release was found when extracellular Cu2+ was removed. The activity of Cu2+ was independent of any effects of deuterium oxide and colchicine, two agents known to interact with microtubules. Increased extracellular Ca2+ concentrations reduced the inhibitory effect of CuCl2 on Ca2+ ionophore-induced histamine release, and Schild plot analysis demonstrated that Cu2+ ions are competitive antagonists of Ca2+ ions.These results indicate that Cu2+ ions in the micromolar range down-regulate anti-IgE- and Ca2+ ionophore-induced histamine release. Since Cu2+ concentration in human plasma is in the micromolar range (30 μM with 10–30% of free Cu2+), it is conceivable that Cu2+ ions contribute to thein vivo regulation of histamine release from human basophils.

Laboratory and clinical risk assessment to treat myelodysplatic syndromes.

Abstract Myelodisplastic syndromes (MDS) are heterogeneous myeloid disorders characterized by peripheral cytopenias and increased risk of transformation into acute myelogenous leukemia (AML). MDS are generally suspected in the presence of cytopenia on routine analysis and the evaluation of bone marrow cells morphology and cellularity leads to correct diagnosis of MDS. The incidence of MDS is approximately five cases per 100,000 people per year in the general population, but it increases up to 50 cases per 100,000 people per year after 60 years of age. Typically MDS affect the elderly, with a median age at diagnosis of 65–70 years. Here the current therapeutic approaches for MDS are evaluated by searching the PubMed database. Establishing the prognosis in MDS patients is a key element of therapy. In fact an accurate estimate of prognosis drives decisions about the choice and timing of the therapeutic options. Therapy is selected based on prognostic risk assessment, cytogenetic pattern, transfusion needs and biological characteristics of the disease, comorbidities and clinical condition of the patients. In lower-risk patients the goals of therapy are different from those in higher-risk patients. In lower-risk patients, the aim of therapy is to reduce transfusion needs and transformation to higher risk disease or AML, improving the quality of life and survival. In higher-risk patients, the main goal of therapy is to prolong survival and to reduce the risk of AML transformation. Current therapies include growth factor support, lenalidomide, immunomodulatory and hypomethylating agents, intensive chemotherapy, and allogenic stem cell transplantation. The challenge when dealing with MDS patients is to select the optimal treatment by balancing efficacy and toxicity.

Ionic regulation of human basophil releasability. III. Effects of Na+ and Ca2+ on histamine release induced by different stimuli

The effects of Na+ and Ca2+ ions on histamine release from human basophils stimulated by anti-IgE, N-formyl-methionyl-leucyl-phenylalanine (FMLP), 4 beta-phorbol 12-myristate 13-acetate (PMA) and Ca2+ ionophore A23187 were evaluated. Isosmotic replacement of Na+ in the extracellular medium with the nonpermeant Na+ analogue choline+ or with glucose led to a significant increase in anti-IgE- (1/5000: 43.7 +/- 7.3% in high Na+ vs 68.9 +/- 7.3% in low Na+, mean +/- SEM, n = 8, P < 0.001), FMLP- (1 microM: 37.9 +/- 2.3% vs 49.5 +/- 4.3%, n = 8, P < 0.01) and PMA-(160 nM: 12.7 +/- 0.9% vs 27.3 +/- 4.3%, n = 8, P < 0.05) induced histamine release, whereas A23187-induced histamine release was reduced (1 microM: 90.4 +/- 2.4% vs 45.4 +/- 3.4%, n = 8, P < 0.0001). The progressive increase in extracellular Na+ concentration was accompanied by a decrease of basophil response to anti-IgE, FMLP and PMA; in contrast, A23187-induced histamine release was up-regulated by Na+. The Na+/H+ exchanger monensin, in the concentration range of 10(-8)-10(-4) M, exerted a dose-dependent inhibitory effect on anti-IgE-, FMLP- and PMA-induced histamine release, but not on A23187-induced histamine release. Extracellular Ca2+ up-regulated the histamine release induced by all the above stimuli. Removal of extracellular Na+ lowered the requirement of extracellular Ca2+ for anti-IgE, FMLP- and PMA-induced histamine release. In contrast with previous observations showing that Na+ supports histamine release from rat peritoneal mast cells and rat basophilic leukaemia cells, these results indicate that Na+ strongly inhibits histamine release from human basophils stimulated by anti-IgE, FMLP and PMA, whereas it enhances Ca2+ ionophore A23187-induced histamine release. The effects of Na+, which are probably related to modulation of membrane potential and/or intracellular pH, vary depending on the cell type and the stimulus employed for cell activation.

Ionic regulation of human basophil releasability. II. Non‐releasing basophils are converted into releasing basophils in a low‐Na+ medium

The effects of different extracellular Na+ and CV2+ concentrations on histamine release from human basophils were investigated. Isosmotic replacement of extracellular Na + either with choline +, a non‐permeant Na + analogue, or glucose significantly increased spontaneous and anti‐IgE‐induced histamine release. Basophils from 12 of 49 normal subjects, which were found not to release histamine upon challenge with an optimal dose of anti‐IgE in a 135 mM NaCl buffer, were converted into releasing basophils when stimulation with anti‐IgE was performed in a low‐Na+ medium. The increase in Na + concentration in the extracellular medium was accompanied by a reduction in the magnitude of basophil response to anti‐IgE, which was significantly more pronounced in non‐releasers than in releasers (per cent inhibition by 70 mM NaCl 75.5 + 3.2 vs 43.5 + 9.0, P < 0.01). At higher Na+ concentrations a progressive and almost complete abrogation of histamine release was observed in non‐releasers, but not in releasers (maximal per cent inhibition at 140 mM NaCl 97.3+1.3 vs 50.4 + 8.6). The Na+/H+ exchanger monensin had a dose‐dependent inhibitory effect on anti‐IgE‐induced histamine release, and the concentration inhibiting 50% of histamine release was l.5 × 10−7M. When basophils were challenged in the presence of different Na+ and C2+ concentrations, it was shown that the two cations have antagonistic effects, which is to say that they down‐regulate and upregulate histamine release, respectively. Moreover, the requirement of extracellular Ca2+ was lowered in a low‐Na+ medium. These results suggest that Na+ and Ca+ ions contribute with opposite effects to the modulation of basophil response to anti‐IgE and that non‐releasing basophils are converted into releasing basophils in a low‐Na + medium.

Target organ damage in a population at intermediate cardiovascular risk, with adjunctive major risk factors: CArdiovascular PREvention Sacco Study (CAPRESS)

The objective of the study is to assess the prevalence of target organ damage (TOD) at carotid, cardiac, renal and peripheral vascular levels in a population at intermediate cardiovascular risk, with adjunctive major risk factors (AMRF). From March 2007 to July 2009 we examined 979 subjects at intermediate cardiovascular risk, as indicated by the Italian algorithm “Progetto Cuore”; the patients were aged 40–69xa0years, sensitized by one or more AMRF such as family history for cardiovascular disease (CVD), being overweight or obese, and smoking habit (more than 10 cigarettes/day). We measured common carotid intima–media thickness (cc-IMT) and plaque at any level, left ventricular mass index (LVMI), urine albumin/creatinine ratio (UACR), and ankle-brachial index (ABI). The prevalence of at least one TOD was 63% (617 subjects), cc-IMT was high in 48.2% (472), UACR abnormal in 14.1% (138), LVMI high in 12.6% (117) and ABI pathological in 9.1% (89). In those with carotid damage 423 had a plaque, amounting to 43.2% of the total population. Of note, carotid damage was present in all subjects with 3 TODs, and in 92% of subjects with 2 TODs. A multivariate logistic regression model including conventional factors and AMRF indicated that age 50–69xa0years, systolic blood pressure, relevant smoking and CV risk score ≥15 were independently and significantly associated with at least one TOD, and at least, with carotid damage. Among the AMRF, peripheral arterial disease was associated with relevant smoking, with an odds ratio (OR) of 3 [confidence interval (CI) 1.80–4.97, pxa0<xa00.0001]; overweight and obesity both had selective associations with cardiac damage with OR 2.75 (CI 1.2–6.3, pxa0<xa00.01) and OR 3.89 (CI 1.61–9.73, pxa0<xa00.01). A substantial proportion of people at intermediate risk, with at least one AMRF have at least one TOD, a major predictor of cardiovascular outcomes.

Does the metabolic syndrome predict subclinical atherosclerotic damage in an asymptomatic population at intermediate cardiovascular risk

BACKGROUND AND AIMSnIt is not clear whether the metabolic syndrome (MetS) is a distinct entity or a combination of risk factors. Several studies showed the association between MetS and cardiovascular disease (CVD). Subclinical target organ damage (TOD) is a recognized marker of atherosclerosis and predictor of cardiovascular events. Increased burden of subclinical atherosclerosis was detected in individuals with MetS. We thus aimed to examine the association between MetS and cumulative or specific TOD and to assess whether MetS predicts TOD better than the risk factors included in current definitions.nnnMETHODS AND RESULTSnWe recorded TOD in 979 patients at intermediate cardiovascular risk with and without MetS according to IDF and NCEP criteria. We measured common carotid intima-media thickness, left ventricular mass index (LVMI), urine albumin to creatinine ratio (UACR), and ankle-brachial index. We found no correlation between having at least one TOD and being positive for MetS. A high UACR was associated with MetS using both IDF and NCEP criteria, while only NCEP identified individuals with increased LVMI. Using a multivariate logistic regression model including MetS, age, sex, waist circumference, triglycerides, HDL cholesterol, blood pressure and blood glucose levels we found no correlations between the presence of MetS and at least one TOD. The associations with high UACR and LVMI disappeared when age, blood pressure and glycemia were counted in.nnnCONCLUSIONnAlthough MetS showed some relation with subclinical renal and cardiac damage, it does not predict TOD any better than the risk factors specified in the definitions.