Luisa Lenti

Immunomodulation during sublingual therapy in allergic children.

The clinical efficacy of sublingual immunotherapy (SLIT) has been demonstrated, but its mechanism of action is still controversial. The most recent experimental observations suggest that a critical role in the modulation of immune response is sustained by Th2 cytokines, such as interleukin‐4 (IL‐4), IL‐5 and IL‐13, by co‐stimulatory molecules, such as CD40 on B cells, and by hormones and neuropeptides. To better understand whether SLIT affects immune responses we used a double‐blind placebo‐controlled design. Eighty‐six children with mild asthma due to allergy to Dermatophagoides pteronyssinus (33 of whom also had rhinoconjunctivitis) were randomly assigned SLIT (n = 47) or placebo (n = 39). We assessed symptom scores using diary cards of each patient and determined the expression of CD40 on B cells and the serum concentration of ECP, IL‐13, prolactin (PRL) and ACTH at enrolment and after 6 months of therapy. We observed a significant reduction in asthma and rhinitis scores in the immunotherapy group compared with the placebo group, no variation in CD40 and ACTH, but a significant decrease in ECP, IL‐13 and PRL after 6 months of therapy (p <0.01). Our results confirm the efficacy and safety of SLIT, and lead us to believe that it could modulate the synthesis of Th2 cytokines, as revealed from the decrease of IL‐13. In addition, the reduction of PRL might be a signal of reduced activation of T lymphocytes.

Short-term treatment with atorvastatin reduces platelet CD40 ligand and thrombin generation in hypercholesterolemic patients

BACKGROUND Soluble CD40L (sCD40L), a substance that maximally reflects in vivo platelet activation, is increased in patients with hypercholesterolemia. We investigated the relation between sCD40L and platelet CD4OL in hypercholesterolemic patients before and after a short-term treatment with atorvastatin. METHODS AND RESULTS Collagen-induced platelet CD40L and plasma levels of sCD40L and prothrombin fragment F1+2, a marker of thrombin generation, were investigated in 30 hypercholesterolemic patients and 20 healthy subjects. Hypercholesterolemic patients were then randomized to either diet (n=15; group A) or atorvastatin 10 mg/d (group B); the aforementioned variables were measured at baseline and after 3 days of treatment. Compared with referents, hypercholesterolemic patients showed higher values of platelet CD40L (P<0.005), sCD40L (P<0.005), and F1+2 (P<0.003). Platelet CD40L was significantly correlated with sCD40L (P<0.001), and the latter was significantly correlated with F1+2 (P<0.001). The intervention trial showed no changes in group A but a significant decrease in platelet CD40L (P<0.01), sCD40L (P<0.002), and F1+2 (P<0.03) in group B. In vitro studies demonstrated that cholesterol enhanced platelet CD40L and CD40L-mediated clotting activation by human monocytes; also, atorvastatin dose-dependently inhibited platelet CD40L expression and clotting activation by CD40L-stimulated monocytes. CONCLUSIONS This study shows that, in hypercholesterolemia, platelet overexpression of CD40L may account for enhanced plasma levels of sCD40L and F1+2. Atorvastatin exerts a direct antithrombotic effect via inhibition of platelet CD40L and CD40L-mediated thrombin generation, independently of its cholesterol-lowering effect.

gp91phox-Dependent Expression of Platelet CD40 Ligand

Background—CD40 ligand (CD40L) expression on platelets is mediated by agonists, but the underlying mechanism is still unclear. Methods and Results—CD40L expression was measured in platelets from healthy subjects both with and without the addition of antioxidants or a phospholipase A2 (PLA2) inhibitor and in platelets from 2 patients with an inherited deficiency of gp91phox. Immunoprecipitation analysis was also performed to determine whether normal platelets showed gp91phox expression. Unlike catalase and mannitol, superoxide dismutase inhibited agonist-induced platelet CD40L expression in healthy subjects. Immunoprecipitation analysis also showed that platelets from healthy subjects expressed gp91phox. In 2 male patients with inherited gp91phox deficiency, collagen-, thrombin-, and arachidonic acid-stimulated platelets showed an almost complete absence of superoxide anion (O2−) and CD40L expression. Incubation of platelets from healthy subjects with a PLA2 inhibitor almost completely prevented agonist-induced O2− and CD40L expression. Conclusions—These data provide the first evidence that platelet CD40L expression occurs via arachidonic acid–mediated gp91phox activation.

Fatty acid synthase (FAS) predictive strength in poorly differentiated early breast carcinomas.

Aims and background Many normal and human cancer tissues express fatty acid synthase (FAS), the major enzyme required for endogenous fatty acid biosynthesis. Strong expression of FAS seems to be associated with a poor prognosis. This study examines the strength of FAS and other common markers of relapse in poorly differentiated breast carcinoma. Materials and methods Fifty-one patients with poorly differentiated ductal infiltrating breast carcinomas were followed up for more than 10 years. Immunohistochemical detection of FAS was associated with morphological features of the tumors, with immunohistochemical expression of c-erbB-2, cathepsin D, estrogen and progesterone receptor status and with DNA ploidy in order to detect a statistical correlation. Results The chi-square test revealed a correlation between FAS and peritumoral lymphatic vessel invasion (PLVI) (P = 0.001). Univariate analysis showed that FAS was correlated with disease-free survival (DFS) (P = 0.0001). Other prognosticators associated with DFS were PLVI (P = 0.002), estrogen (P = 0.008) and progesterone receptor status (P = 0.007). Bivariate analysis showed that FAS was a further prognostic discriminant of DFS within the ER, PgR and PLVI subsets. Discussion FAS is a reliable prognosticator of recurrence in poorly differentiated early breast carcinomas. Association of FAS with PLVI may be useful to plan a correct follow-up in patients with breast neoplasms.

Inherited Human gp91phox Deficiency Is Associated With Impaired Isoprostane Formation and Platelet Dysfunction

Object—Platelet isoprostane 8-ISO-prostaglandin F2&agr; (8-iso-PGF2&agr;), a proaggregating molecule, is believed to derive from nonenzymatic oxidation of arachidonic acid. We hypothesized that NADPH is implicated in isoprostane formation and platelet activation. Methods and Results—We studied 8-iso-PGF2&agr; in platelets from 8 male patients with hereditary deficiency of gp91phox, the catalytic subunit of NADPH oxidase, and 8 male controls. On stimulation, platelets from controls produced 8-iso-PGF2&agr;, which was inhibited −8% by aspirin and −58% by a specific inhibitor of gp91phox. Platelets from patients with gp91phox hereditary deficiency had normal thromboxane A2 formation but marked 8-iso-PGF2&agr; reduction compared with controls. In normal platelets incubated with a gp91phox inhibitor or with SQ29548, a thromboxane A2/isoprostane receptor inhibitor, platelet recruitment, an in vitro model of thrombus growth, was reduced by 44% and 64%, respectively; a lower effect (−17%) was seen with aspirin. Moreover, thrombus formation under shear stress (blood perfusion at the wall shear rate of 1500 s−1) was reduced in samples in which isoprostane formation was inhibited by NADPH oxidase inhibitors. In gp91phox-deficient patients, agonist-induced platelet aggregation was within the normal range, whereas platelet recruitment was reduced compared with controls. Incubation of platelets from gp91phox-deficient patients with 8-iso-PGF2&agr; dose-dependently (1 to 100 pmol/L) increased platelet recruitment by mobilizing platelet Ca2+ and activating gpIIb/IIIa; a further increase in platelet recruitment was detected by platelet coincubation with l-NAME, an inhibitor of NO synthase. Conclusion—This study provides the first evidence that platelet 8-iso-PGF2&agr; maximally derives from gp91phox activation and contributes to platelet recruitment via activation of gpIIb/IIIa.

Protein S and HIV infection the role of anticardiolipin and anti-protein S antibodies

It has recently been reported that a large proportion of patients with HIV infection have low free protein S levels. In this study we show that protein S (PS) activity levels, as well as PS antigen (Ag), were significantly lower in 35 HIV-1 infected patients than in the control population (p < 0.001). When we divided HIV infected patients into three groups according to their CD4+ counts, we found that PS levels were significantly lower in patients with < 100 CD4+ cells/ul. In order to investigate the possible role of (auto)immune response in the pathogenesis of PS deficiency, the presence of anticardiolipin antibodies (aCL) and/or of the specific antibodies to protein S was evaluated. A high prevalence (77.1%) of aCL in both symptomatic and asymptomatic subjects was observed. The screening for specific anti-PS antibodies, performed by immunoblotting, showed an overall positivity of 28.6% in anti-HIV+ patients, with a higher prevalence in symptomatic than in asymptomatic patients. Interestingly, the prevalence of the positivity for anti-PS antibodies was found to be higher in anti-HIV+ patients with PS levels < 50%. Taken collectively, our findings suggest that at least one of the mechanisms through which PS levels are decreased in HIV infection, is due to the presence of specific autoantibodies.

Vitamin E inhibits collagen-induced platelet activation by blunting hydrogen peroxide.

In this study, we investigated whether vitamin E at concentrations achievable in blood after supplementation inhibits platelet function in humans. Gel-filtered platelets were incubated 30 minutes with scalar concentrations (50 to 250 mmol/L) of vitamin E and then stimulated with collagen. Compared with controls, vitamin E inhibited collagen-induced platelet aggregation and thromboxane A2 formation in a dose-dependent manner. Furthermore, vitamin E inhibited, in a dose-dependent manner, Ca(2+) mobilization and formation of inositol 1,4,5-triphosphate. Because it was previously shown that hydrogen peroxide formation mediates arachidonic acid metabolism and phospholipase C activation in collagen-induced platelet activation, we investigated whether vitamin E was able to blunt hydrogen peroxide. In experiments performed in unstimulated platelets supplemented with hydrogen peroxide and in collagen-stimulated platelets, vitamin E was able to blunt hydrogen peroxide. In 6 healthy subjects given vitamin E for 2 weeks (600 mg/d), we found a significant decrease of collagen-induced H(2)O(2) formation, platelet aggregation, and calcium mobilization. This study demonstrated in vitro and ex vivo that vitamin E inhibits collagen-induced platelet activation by blunting hydrogen peroxide formation.

LDL are oxidatively modified by platelets via GP91phox and accumulate in human monocytes

Oxidative stress‐mediated LDL modification has a key role in initiation of the atherosclerotic process. Platelets produce reactive oxidant species (ROS) upon stimulation with agonist, but it is uncertain whether they are able to oxidatively modify LDL. Human platelets taken from healthy subjects were incubated with LDL, then stimulated with collagen. Compared with unstimulated platelets, collagen‐stimulated platelets induced LDL modification as shown by enhanced conjugated dienes and lysophosphatidylcho‐line formation, electrophoretic mobility, Apo B‐100 degradation, and monocyte LDL uptake. Activated platelets also induced a marked reduction of vitamin Ε contained in LDL. A significant inhibition of LDL oxidation was observed in platelets treated with arachi‐donyl trifluomethyl ketone (AACOCF3), an inhibitor of phospolipase A2. The experiments reported above were also conducted in patients with hereditary deficiency of gp91phox, the central core of NADPH oxidase, and in patients with hypercholesterolemia. Platelets from gp91 phox‐deficient patients produced a small amount of ROS and weakly modified LDL. Conversely, platelets from hypercholesterolemic patients showed enhanced ROS formation and oxidized LDL more than platelets from healthy subjects. This study provides evidence that platelets modify LDL via NADPH oxidase‐mediated oxidative stress, a phenomenon that could be dependent on arachidonic acid activation. This finding suggests a role for platelets in favoring LDL accumulation within atherosclerotic plaque.—Carnevale, R., Pignatelli, P., Lenti, L., Buchetti B., Sanguigni, V., Di Santo, S., Violi, F. LDL are oxidatively modified by platelets via GP91phox and accumulate in human monocytes. FASEB J. 21, 927–934 (2007)

Ganglioside Expression in Human Pancreatic Islets

Recent biochemical studies have shown that the cytoplasmic islet cell–antibody autoantigen has properties of a monosialoganglioside (GM). To characterize islet glycolipids and ascertain whether islets express unique gangliosides, we determined the pattern of ganglioside expression in whole human pancreas and isolated human islets using high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC). The major gangliosides detected in glycolipid extracts of whole human pancreas were GM3, GD3 (disialoganglioside), and in a lesser amount, a GD1a-comigrating ganglioside. In contrast to whole human pancreas, isolated human islets were found to predominantly express GM3, an acidic glycolipid comigrating with GM2, and a ganglioside with mobility between GM2 and GM1 by both HPLC and HPTLC. Quantitation of the major ganglioside UV peaks seen on HPLC gave the following results. In whole pancreas, GM3 represented 66.7% of total gangliosides detected; an asialoglycolipid comigrating with GM2, 2.0%; a ganglioside migrating between GM2 and GM1, 2.6%; GD3, 22.6%; and a GD1a-comigrating ganglioside, 6.1%. In isolated islets, these components were found at the following levels: GM3, 14.9%; GM2-comigrating glycolipid, 74.2%; a ganglioside migrating between GM2 and GM1, 9.8%; GD3, 1.1%; and the GD1a-comigrating ganglioside, not detectable.

Oxidative stress‐mediated platelet CD40 ligand upregulation in patients with hypercholesterolemia: effect of atorvastatin

Summary.  Objectives: We speculated that in patients with hypercholesterolemia CD40L overexpression could depend on low‐density lipoprotein (LDL)‐induced enhanced intraplatelet formation of O2·− and statin could reduce platelet CD40L via interference with platelet O2·− production. Background: CD40L is a protein with inflammatory and thrombotic properties. CD40L is upregulated in platelets from hypercholesterolemic (HC) patients but the underlying mechanism is unclear. Methods: Collagen‐induced platelet CD40L and platelet O2·− expression were investigated in 40 HC patients and 40 healthy subjects. HC patients were then randomized to either a diet (n = 20) (group A) or atorvastatin 10 mg day (n = 20) (group B); the above variables were measured at baseline and after 3 and 30 days of treatment. O2·− and CD40L were also measured in vitro in LDL‐treated platelets with or without nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor or atorvastatin added. Results: Compared with controls, HC patients showed higher values of platelet CD40L (P < 0.001) and O2·− (P < 0.001). Platelet CD40L was significantly correlated with O2·− (P < 0.001). The interventional trial showed no changes in group A and a significant and parallel decrease in platelet CD40L (P < 0.001) and O2·− (P < 0.001) in group B. In vitro studies demonstrated that LDL‐induced platelet CD40L and GP IIb/IIIa (PAC1 binding) activation via the NADPH oxidase pathway. CD40L upregulation was counteracted by atorvastatin in a dose‐dependent fashion. Conclusions: This study suggests that in patients with hypercholesterolemia platelet CD40L is upregulated via NADPH oxidase‐dependent O2·− generation. Atorvastatin downregulated CD40L with an oxidative stress‐mediated mechanism likely involving platelet NADPH oxidase, an effect that seemed to be independent of its cholesterol‐lowering action.