André Luiz Franco Sampaio

Pharmacological study of anti-allergic activity of Syzygium cumini (L.) Skeels

Myrtaceae is a plant family widely used in folk medicine and Syzygium and Eugenia are among the most important genera. We investigated the anti-allergic properties of an aqueous leaf extract of Syzygium cumini (L.) Skeels (SC). HPLC analysis revealed that hydrolyzable tannins and flavonoids are the major components of the extract. Oral administration of SC (25-100 mg/kg) in Swiss mice (20-25 g; N = 7/group) inhibited paw edema induced by compound 48/80 (50% inhibition, 100 mg/kg; P <or= 0.05) and, to a lesser extent, the allergic paw edema (23% inhibition, 100 mg/kg; P <or= 0.05). SC treatment also inhibited the edema induced by histamine (58% inhibition; P <or= 0.05) and 5-HT (52% inhibition; P <or= 0.05) but had no effect on platelet-aggregating factor-induced paw edema. SC prevented mast cell degranulation and the consequent histamine release in Wistar rat (180-200 g; N = 7/group) peritoneal mast cells (50% inhibition, 1 microg/mL; P <or= 0.05) induced by compound 48/80. Pre-treatment of BALB/c mice (18-20 g; N = 7/group) with 100 mg/kg of the extract significantly inhibited eosinophil accumulation in allergic pleurisy (from 7.662 +/- 1.524 to 1.89 +/- 0.336 x 10(6)/cavity; P <= 0.001). This effect was related to the inhibition of IL-5 (from 70.9 +/- 25.2 to 12.05 +/- 7.165 pg/mL) and CCL11/eotaxin levels (from 60.4 +/- 8.54 to 32.8 +/- 8.4 ng/mL) in pleural lavage fluid, using ELISA. These findings demonstrate an anti-allergic effect of SC, and indicate that its anti-edematogenic effect is due to the inhibition of mast cell degranulation and of histamine and serotonin effects, whereas the inhibition of eosinophil accumulation in the allergic pleurisy model is probably due to an impairment of CCL11/eotaxin and IL-5 production.

Role of endothelins on lymphocyte accumulation in allergic pleurisy.

Endothelins participate in different aspects of inflammatory reactions, including edema formation and eosinophil accumulation in allergic reaction. In this study, we demonstrated a role for endogenous endothelins in eosinophil and T lymphocyte recruitment and cytokine secretion in a murine model of allergic inflammation. Intrathoracic stimulation with endothelin‐1 triggered a neutrophil accumulation at 4 h, concomitant with an increase of CD4+ and CD8+ T lymphocyte populations. Antigen challenge in sensitized animals leads to an increase in eosinophil and mononuclear cell numbers at 24 h. Treatment with ETA receptor antagonist (BQ123) inhibited antigen‐induced eosinophil and mononuclear cell migration, whereas the selective ETB receptor antagonist BQ‐788 was ineffective. The latter effect of BQ‐123 was due to inhibition of CD4+ and CD8+ T lymphocytes. Treatment with BQ‐123 also inhibited interleukin‐5 levels in the exudate and plasma as well as intracellular staining of interleukin‐4, interleu‐kin‐5, and interferon‐γ in CD4+ lymphocytes. These findings suggest that endogenous endothelins contribute to allergic inflammation by modulating lymphocyte recruitment and cytokine production. J. Leukoc. Biol. 67: 189–195; 2000.

Immunomodulating and antiviral activities of Uncaria tomentosa on human monocytes infected with Dengue Virus-2

Uncaria tomentosa (Willd.) DC., a large woody vine native to the Amazon and Central American rainforests has been used medicinally by indigenous peoples since ancient times and has scientifically proven immunomodulating, anti-inflammatory, cytotoxic and antioxidant activities. Several inflammatory mediators that are implicated in vascular permeability and shock are produced after Dengue Virus (DENV) infection by monocytes, the primary targets for virus replication. Here we assessed the immunoregulatory and antiviral activities from U. tomentosa-derived samples, which were tested in an in vitro DENV infection model. DENV-2 infected human monocytes were incubated with U. tomentosa hydro-alcoholic extract or either its pentacyclic oxindole alkaloid-enriched or non-alkaloid fractions. The antiviral activity was determined by viral antigen (DENV-Ag) detection in monocytes by flow cytometry. Our results demonstrated an in vitro inhibitory activity by both extract and alkaloidal fraction, reducing DENV-Ag+ cell rates in treated monocytes. A multiple microbead immunoassay was applied for cytokine determination (TNF-alpha, IFN-alpha, IL-6 and IL-10) in infected monocyte culture supernatants. The alkaloidal fraction induced a strong immunomodulation: TNF-alpha and IFN-alpha levels were significantly decreased and there was a tendency towards IL-10 modulation. We conclude that the alkaloidal fraction was the most effective in reducing monocyte infection rates and cytokine levels. The antiviral and immunomodulating in vitro effects from U. tomentosa pentacyclic oxindole alkaloids displayed novel properties regarding therapeutic procedures in Dengue Fever and might be further investigated as a promising candidate for clinical application.

Participation of endogenous endothelins in delayed eosinophil and neutrophil recruitment in mouse pleurisy.

Abstract.Objective: Investigate the role of endothelins in leukocyte recruitment in allergic and non allergic inflammation.¶Methods: Pleurisy was induced in mice by intrathoracic injection of ovalbumin (OVA; in sensitized animals), E. coli LPS, carrageenan, Mycobacterium bovis (BCG) or zymosan. Animals were treated with BQ-123 or BQ-788 (1.5-150 pmol/cavity), or intravenously with bosentan (30 mg/kg).¶Results: None of the ET receptor antagonists modified early neutrophil recruitment (at 4h) induced by OVA, LPS, carrageenan, BCG or zymosan or plasma leakage caused by carrageenan or zymosan. Mononuclear and eosinophil accumulation triggered by OVA were reduced by BQ-123 (150 pmol/cavity) or bosentan (68 and 43% inhibition of eosinophilia), but unaffected by BQ-788. BQ-123 and bosentan also inhibited LPS increases in neutrophil (by 67 and 40%) and eosinophil (by 63 and 74%) at 24 h.¶Conclusions: Endothelins, acting via ETA receptors, play a role in late eosinophil and neutrophil accumulation (24h), but not in the acute (4h) neutrophilic response.

Effects of endothelin ETA receptor antagonism on granulocyte and lymphocyte accumulation in LPS‐induced inflammation

Endothelin peptides play active roles in different aspects of inflammation. This study investigates the contribution of endogenous endothelins to lipopolysaccharide (LPS) pulmonary inflammation by assessing the influence of ETA receptor antagonism on leukocyte accumulation, granulocyte adhesion molecule expression, and chemokine/cytokine modulation. Local pretreatment with BQ‐123 or A‐127722 (150 pmol), two selective and chemically unrelated endothelin ETA receptor antagonists, inhibits neutrophil and eosinophil accumulation in LPS‐induced pleurisy at 24 h but not neutrophil migration at 4 h. The effect of endothelin antagonism on neutrophil accumulation at 24 h was concomitant with inhibition of eosinophil and CD4 and CD8 T lymphocyte influx. It is surprising that the ETA receptor blockade did not inhibit the accumulation of γδ T lymphocytes, cells that are important for granulocyte recruitment in this model. Blockade of ETA receptors did not influence the expression of adhesion molecules (CD11b, CD49d) on granulocytes but abrogated the increase in tumor necrosis factor α levels 4 h after LPS stimulation and also markedly inhibited increases in levels of interleukin‐6 and keratinocyte‐derived chemokine/CXC chemokine ligand 1 but not eotaxin/chemokine ligand 11. Thus, acting via ETA receptors, endogenous endothelins play an important role in early cytokine/chemokine production and on granulocyte and lymphocyte mobilization in LPS‐induced pleurisy.

Lymphocyte activation and cytokine production by Pisum sativum agglutinin (PSA) in vivo and in vitro.

Mice spleen cells were incubated in vitro for 24 h with Pisum sativum agglutinin (PSA). The addition of these supernatants (SN) to macrophage cultures induced the production of nitric oxide (NO) by these cells in a dose-dependent manner. NO release was blocked in the presence of IFN gamma antibodies and partially inhibited by TNF alpha antibodies. The ability of PSA in inducing the production of IFN gamma and TNF alpha by spleen lymphocytes was confirmed assaying these cytokine levels in the SN. Spleen cells stimulated in vitro with PSA were highly activated showing an increased expression of the earlier activation marker, CD69, and a great proliferative response. On the other hand, spleen cells obtained from mice treated with PSA 24 h earlier, did not produce significant levels of IFN gamma or TNF alpha when incubated in vitro and showed a significantly lower proliferation rate when pulsed in vitro with PSA or Concanavalin A (ConA). The lower responsiveness to mitogens was also evident after 48 and 72 h after the treatment in vivo with the lectin. Nevertheless, the flow cytometric analysis of spleen lymphocytes obtained from PSA-treated animals showed a high degree of activation in cells CD3+. There was a decrease in the expression of L-selectin and VLA-4, when compared to controls, in parallel with a significant increase in the expression of CD69 and CD122 (IL-2R) in lymphocytes recovered from PSA-injected animals. The data point to evidence that PSA induces immunomodulatory effects, activating spleen lymphocytes in vivo, which become unresponsive to a second stimulation in vitro.

An in vitro model for dengue virus infection that exhibits human monocyte infection, multiple cytokine production and dexamethasone immunomodulation

An important cytokine role in dengue fever pathogenesis has been described. These molecules can be associated with haemorrhagic manifestations, coagulation disorders, hypotension and shock, all symptoms implicated in vascular permeability and disease worsening conditions. Several immunological diseases have been treated by cytokine modulation and dexamethasone is utilized clinically to treat pathologies with inflammatory and autoimmune etiologies. We established an in vitro model with human monocytes infected by dengue virus-2 for evaluating immunomodulatory and antiviral activities of potential pharmaceutical products. Flow cytometry analysis demonstrated significant dengue antigen detection in target cells two days after infection. TNF-alpha, IFN-alpha, IL-6 and IL-10 are produced by in vitro infected monocytes and are significantly detected in cell culture supernatants by multiplex microbead immunoassay. Dexamethasone action was tested for the first time for its modulation in dengue infection, presenting optimistic results in both decreasing cell infection rates and inhibiting TNF-alpha, IFN-alpha and IL-10 production. This model is proposed for novel drug trials yet to be applied for dengue fever.

POLYPHENOL AND TRITERPENOID CONSTITUENTS OF Eugenia florida DC. (MYRTACEAE) LEAVES AND THEIR ANTIOXIDANT AND CYTOTOXIC POTENTIAL

Priscila F. P. Santosa,b, Luiz N. L. F. Gomesb, José L. Mazzeic, Ana Paula A. Fontãoc, André L. F. Sampaioc, Antonio C. Sianic,# and Ligia M. M. Valenteb,* Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Campus Angra dos Reis, 23953-030 Angra dos Reis – RJ, Brasil Instituto de Química, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro – RJ, Brasil Fundação Oswaldo Cruz, Instituto de Tecnologia em Fármacos, Rua Sizenando Nabuco 100, Manguinhos, 21041-250 Rio de Janeiro – RJ, Brasil