Effect of brown spider venom on basement membrane structures

Citation
Ss. Veiga et al., Effect of brown spider venom on basement membrane structures, HISTOCHEM J, 32(7), 2000, pp. 397-408
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Medical Research Diagnosis & Treatment
Journal title
HISTOCHEMICAL JOURNAL
ISSN journal
0018-2214 → ACNP
Volume
32
Issue
7
Year of publication
2000
Pages
397 - 408
Database
ISI
SICI code
0018-2214(200007)32:7<397:EOBSVO>2.0.ZU;2-X
Abstract
Loxoscelism or necrotic arachnidism are terms used to describe lesions and reactions induced by bites (envenomation) from spiders of the genus Loxosce les. Envenomation has been reported to provoke dermonecrosis and haemorrhag e at the bite site and haemolysis, disseminated intravascular coagulation a nd renal failure. The purpose of this work was to study the effect of the v enom of the brown spider Loxosceles intermedia on basement membrane structu res and on its major constituent molecules. Light microscopy observations s howed that L. intermedia venom obtained through electric shock, which repro duces two major signals of Loxoscelism in the laboratory, exhibits activity toward basement membrane structures in mouse Engelbreth-Holm-Swarm (EHS) s arcoma. Basement degradation was seen by a reduced periodic acid-Schiff (PA S) and alcian blue staining as well as by a reduced immunostaining for lami nin when compared to control experiments. Electron microscopy studies confi rmed the above results, showing the action of the venom on EHS-basement mem branes and demonstrating that these tissue structures are susceptible to th e venom. Using purified components of the basement membrane, we determined through SDS-PAGE and agarose gel that the venom is not active toward lamini n or type IV collagen, but is capable of cleaving entactin and endothelial heparan sulphate proteoglycan. In addition, when EHS tissue was incubated w ith venom we detected a release of laminin into the supernatant, corroborat ing the occurrence of some basement membrane disruption. The venom-degradin g effect on entactin was blocked by 1,10-phenanthroline, but not by other p rotease inhibitors such as PMSF, NEM or pepstatin-A. By using light microsc opy associated with PAS staining we were able to identify that 1,10-phenant hroline also inhibits EHS-basement membrane disruption evoked by venom, cor roborating that a metalloprotease of venom is involved in these effects. De gradation of these extracellular matrix molecules and the observed suscepti bility of the basement membrane could lead to loss of vessel and glomerular integrity, resulting in haemorrhage and renal problems after envenomation.