Degradation of Fibronectin by Serine-proteinases from Lonomia achelous  Hemolymph

Lucena, S., Guerrero, B., Salazar, A., Gil, A., Carvajal, Z., Arocha-Piñango, C.

Instituto Venezolano de Investigaciones Científicas (IVIC). Centro de Medicina Experimental. Laboratorio de Fisiopatología. Caracas, Venezuela.

The Lonomiaachelous caterpillar, distributed in the southern Venezuela and northern of Brazil, produces an acute hemorrhagic syndrome in persons who have been in contact with their spines. In some patients fresh healed wounds are re-opened and start to bleed. In order to try to give an explanation to this symptomatology, we have evaluated the effect of the Lonomin V (LV), and Lonomin V2 (LV2) on the matrix protein fibronectin (FN), involved in the wound healing process. The LV and LV2 are proteins isolated from the hemolymph of this caterpillar which present the following activities: amidolytic activity similar to plasmin and to urokinase, and fibrinolytic activity in fibrin plates. Materials and Methods: We studied the effect of LV and LV2 on FN, incubated at a relation of 1 mg LV/100mg FN for 6 hours at 37 ºC evaluating: a) the integrity of FN's molecular structure by immunoblotting using an anti-FN antibody and also by HPLC; b) the crosslinking of the FN previously treated with LV and LV2 to fibrin; and c) the adhesion of platelets to FN treated in the same way, by measuring the activity of phosphatase acid. Results: a) the FN is degraded by LV and LV2, producing a pattern of degradation that were similar in both fractions generating 3 principal fragments of 300, 62 and 27 kD determined by Gel Filtration Chromatography by HPLC (Protein-Pak-300). These effect were diminished in presence of benzamidine, aprotinine and iodoacetic acid. b) the incorporation of FN previously treated with LV into the crosslinked fibrin by FXIIIa was markedly reduced. c) the adhesion of platelets to FN treated with LV was diminished significantly (p <0,01) in a dose-dependent manner with regard to the ratio of LV: FN: 1:100 = 32,6 %; 5:100 = 25,8%; 25:100 = 13,9%; 50:100 = 8,1%. Conclusions: the hemolymph from Lonomiaachelous caterpillar contains a serine-proteinase: the Lonomin V, which can be the same as Lonomin V2 or an isoform which degrade fibronectin, interfering his crosslinking to fibrin, and also with the capacity to promote the adhesion of platelets. This effect on fibronectin can partly explain the haemorrhagic syndrome accompanied by wound re-opening, seen in persons who have been in contact with the mentioned caterpillar.

This project was financed by the National Fundation of Science, Technology and Innovation (FONACIT) and by the Venezuelan Institute of Scientific Investigations (IVIC).

Correspondence to: bguerrer@medicina.ivic.ve