Lonomia obliqua (Lepidoptera, Saturniidae) caterpillar bristle extract induces direct lysis by cleaving erythrocyte membrane glycoproteins

Lonomia obliqua caterpillar bristle extract induces hemolysis in vitro on washed human and rat erythrocytes, in either the absence or presence of exogenous lecithin. In the former condition, phospholipases A(2) are key enzymes involved in hemolysis. However, the mechanism whereby this extract causes direct hemolysis is not known. Thus, the aim of this study was to investigate the hemolytic mechanism of the crude extract of the caterpillar L obliqua on human erythrocytes in the absence of lecithin. The extract significantly increased the erythrocyte osmotic fragility and promoted the removal of glycophorins A and C, and band 3 from the erythrocyte membrane. The use of Ca(2+) and Mg(2+) ions significantly potentiated glycoprotein removal, remarkably of erythrocyte band 3. The composition of fatty acids was analyzed by HPLC in both L obliqua caterpillar bristle extract and human erythrocyte membranes incubated with the extract. The levels of unsaturated fatty acids were remarkably augmented in erythrocytes incubated with the extract than in control erythrocytes, modifying thereby the saturated/unsaturated fatty acid ratio. Altogether, evidence is provided here that the interplay of at least three mechanisms of action accounts for the direct activity of the bristle extract on erythrocyte membrane, leading to hemolysis: the removal of glycoproteins and band 3; the insertion of fatty acids; and the action of phospholipases. Such mechanisms might affect erythrocyte flexibility and deformability, which may induce hemolysis by increasing erythrocyte fragility. However, whether the direct hemolytic activity of L obliqua caterpillar is the major cause of intravascular hemolysis during envenomation still needs further investigation. (C) 2010 Elsevier Ltd. All rights reserved.FAPESP[00/11432-9]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP[01/07643-7]FAPESP[08/02996-8]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq[303711/2007-8]Fundacao Butantan and Secretaria de Ciencia e Tecnologia do Estado do Tocantins (SECT-TO)Fundação ButantanSecretaria de Ciencia e Tecnologia do Estado do Tocantins (SECT-TO

Plasma cytokine expression after lower-limb compression in rats

OBJECTIVES: Muscle injury due to crushing (muscle compression injury) is associated with systemic manifestations known as crush syndrome. A systemic inflammatory reaction may also be triggered by isolated muscle injury. The aim of this study was to investigate the plasma levels of interleukins (IL) 1, 6 and 10 and tumor necrosis factor alpha (TNF-&#945;), which are markers for possible systemic inflammatory reactions, after isolated muscle injury resulting from lower-limb compression in rats.METHODS: Male Wistar rats were subjected to 1 h of compression of their lower limbs by means of a rubber band. The plasma levels of IL 1, 6 and 10 and TNF-&#945; were measured 1, 2 and 4 h after the rats were released from compression.RESULTS: The plasma levels of IL 10 decreased in relation to those of the other groups, with a statistically significant difference (p < 0.05). The method used did not detect the presence of IL 1, IL 6 or TNF-&#945;.CONCLUSION: Our results demonstrated that the changes in plasma levels of IL 10 that were found may have been a sign of the presence of circulating interleukins in this model of lower-limb compression in rats