[Hydatid cyst fluid (Echinococcus granulosus) biochemistry. Influence of site on cyst permeability]

Proline modulates the effect of bisphosphonate on calcium levels and adenosine triphosphate production in cell lines derived from bovine Echinococcus granulosus protoscoleces

Bisphosphonates have been proposed as pharmacological agents against parasite and cancer cell growth. The effect of these compounds on helminthic cell viability and acellular compartment morphology, however, has not yet been studied. The effects of different types of bisphosphonates, namely etidronate (EHDP), pamidronate (APD), alendronate (ABP), ibandronate (IB) and olpadronate (OPD), and their interaction with amiloride, 1,25-dihydroxycholecalciferol (D3) and proline were evaluated on a cell line derived from bovine Echinococcus granulousus protoscoleces (EGPE) that forms cystic colonies in agarose. The EGPE cell line allowed testing the effect of bisphosphonates alone and in association with other compounds that could modulate calcium apposition/deposition, and were useful in measuring the impact of these compounds on cell growth, cystic colony formation and calcium storage. Decreased cell growth and cystic colony formation were found with EHDP, IB and OPD, and increased calcium storage with EHDP only. Calcium storage in EGPE cells appeared to be sensitive to the effect of amiloride, D3 and proline. Proline decreased calcium storage and increased colony formation. Changes in calcium storage may be associated with degenerative changes of the cysts, as shown in the in vitro colony model and linked to an adenosine triphosphate (ATP) decrease. In conclusion, bisphosphonates could be suitable tempering drugs to treat cestode infections.

Morphological and biological characterization of cell line developed from bovine Echinococcus granulosus

The taeniid tapeworm Echinococcus granulosus is the causative agent of echinococcal disease, a major zoonosis with worldwide distribution. Several efforts to establish an in vitro model of E. granulosus have been undertaken; however, many of them have been designed for Echinococcus multilocularis. In the present study, we have described and characterized a stable cell line obtained from E. granulosus bovine protoscoleces maintained 3 yr in vitro. Growth characterization, morphology by light, fluorescent and electronic microscopy, and karyotyping were carried out. Cell culture origin was confirmed by immunofluorescent detection of AgB4 antigen and by PCR for the mitochondrial cytochrome c-oxidase subunit 1 (DCO1) gene. Cells seeded in agarose biphasic culture resembled a cystic structure, similar to the one formed in secondary hosts. This cell line could be a useful tool to research equinococcal behavior, allowing additional physiological and pharmacological studies, such as the effect of growth factors, nutrients, and antiparasitic drugs on cell viability and growth and on cyst formation.

Ontogenetic changes in helminth membrane function

During their life-cycle many parasites experience a wide range of environments including free living and those provided by a variety of intermediate and final hosts. The nutritional requirements of parasites are met by physiological processes adapted to exploit the physicochemical characteristics provided by different hosts. In helminth parasites these adaptations are frequently expressed on the tegumentary surface. As an example of adaptations within the Trematoda, the control of monosaccharide transport in Proterometra sp. is described. Environmental sodium, although not directly involved in the uptake process, nevertheless regulates the expression of transport capabilities. In the Cestoda, the uptake of monosaccharides and amino acids is described for Hymenolepis diminuta. The metacestode of this tapeworm inhabits the blood system of an arthropod, and the adult the gut of a mammal. There are quantitative and qualitative differences in the amino acids and monosaccharides in these two environments and these are reflected in the transport mechanisms exhibited by the two forms of the life-cycle. In Echinococcus granulosus the transfer of amino acids, sugars and macromolecules across the membranes of hydatid cysts and protoscoleces is described. The major difference between these two stages in the life-cycle relates to the ability of hydatid cysts to absorb macromolecules, whereas protoscoleces are impermeable to these compounds. The potential for future work is emphasized.

Host serum protein levels in cysts of human hydatidosis

8 proteins (albumin, IgG, IgM, IgA, C3c, C4, orosomucoid and alpha 1 antitrypsin) were determined by laser immunonephelometry in hydatid cyst fluid from cysts and sera from 16 patients. The cystic level of albumin was 34.5 +/- SD 59.1 micrograms/ml (range 3.6-85); of IgG 12.9 +/- 18.7 micrograms/ml (1.9-75); of IgM 10.5 +/- 10.4 micrograms/ml (3-37); and of IgA 7.2 +/- 3.5 micrograms/ml (4-19.7). The 4 other proteins represented a smaller fraction: C3c, 0.9 +/- 0.6 micrograms/ml (0.5-2.5); C4, 1.3 +/- 0.9 micrograms/ml (0.5-3.5); orosomucoid, 2.8 +/- 2.3 micrograms/ml (1.4-9.2); and alpha 1-antitrypsin, 5 +/- 4.5 micrograms/ml (2-19). These 8 host proteins constituted 24.6 +/- 24.5% (2.4-76) of the total hydatid cyst fluid proteins (343.7 +/- 172.1 micrograms/ml, range 180-900). The albumin/IgG ration of 3 +/- 2.8 (0.4-10.8) in hydatid cyst fluid was more variable than that in sera, 2 +/- 0.5 (1.2-2.7).