The induction of pulmonary inflammation by leptospiral glycolipoprotein (GLP) and by ouabain as a model for the study of leptospirosis related acute respiratory distress syndrome (ARDS)
Gonçalves, C.F.1,2 ; Conceição, M.C.B.1; Gomes-Garcia, D3; Rocha, E.K.1;Bozza, P.T. 2; Burth, P. 3; Castro Faria Neto, H.C.C. 2 ; Castro Faria, M.V. 1
1 Dep. de Biologia Celular e Genética, IBRAG, UERJ, Rio de Janeiro, RJ.
2 Dep. de Fisiologia e Farmacodinâmica, IOC, FIORUZ, Rio de Janeiro, RJ.
3 Dep. de Biologia Celular e Molecular, Inst. de Biologia, UFF, Niterói, RJ.
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GLP is the bacterial fraction displaying endotoxic properties in Leptospira, differing from other Gram(-) bacteria, in which the lipopolysaccharide (LPS) is the endotoxin. We have already shown that GLP is a potent and specific Na+,K+-ATPase inhibitor, and that some lipid GLP components (i.e., palmitoleic, palmitovaccenic, and oleic acids) are the active Na+,K+-ATPase inhibitors. Liver and kidney are the main organs colonized by Leptospira. We proposed that bacterial lysis consequent to the host immune response would release GLP, leading to Na+,K+-ATPase inhibition and provoking the quite peculiar metabolic alterations of these organs. We also showed augmented levels of circulating unsaturated fatty acids, such as oleic acid (OA), together with low albumin serum levels, which could be involved in the lung failure observed in patients with severe leptospirosis (Infection and Immunity, 65 (4): 2557-2560, 1997). We yet showed the ability of OA to induce pulmonary inflammation in mice. In this work we studied the pulmonary inflammation induced by GLP and by ouabain in mice. Male Swiss mice (about 30g) were injected with GLP and ouabaín (0.025ml, 0,3mM) intratracheally (i.t.). Bronco alveolar lavage (BAL) was performed after killing the animals with CO2. The BAL fluid was used to access total and differential cell numbers, to perform lipid body enumeration (Proc Natl Acad Sci. USA, 98:11091-96, 1996) and to quantitate protein, using the BCA method (Pierce). The injection of GLP or ouabain induced an increase in the total leukocyte number in the BAL fluid after 24h. The differential analysis showed a predominance of neutrophils in both stimulus. Staining with Osmium revealed an increase in lipid body numbers in the cells from stimulated animals. Furthermore, the enhanced total protein in the BAL fluid of the stimulated group, indicated edema formation. In conclusion, the GLP or ouabain injection induced an inflammatory response in the lung characterized by cell migration, cell activation with lipid body and edema formation. This model strengthen the importance of the Na, K pump inhibition in pulmonary edema formation and may be useful in the study of leptospirosis related ARDS. APOIO CNPq
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