Hadar Isseroff

Proline in fascioliasis: I. Comparative activities of ornithine-delta-transaminase and proline oxidase in Fasciola and in mammalian livers.

The source was sought for the high levels of proline observed in the bile of animals infected with Fasciola hepatica. Toward this end the activities of 2 key enzymes in the metabolism of proline were measured. Ornithine-4-transaminase was compared in homogenates of Fasciola, rabbit liver, and rat liver. The specific activity of the Fasciola enzyme is more than 10 times greater than that of rabbit liver and more than 7 times greater than that of rat liver. Furthermore, proline oxidase which breaks down proline in mammalian liver was absent or very low in homogenates of Fasciola. These observations strongly suggest that the worm is the source of the excessive free proline. Recent studies by Kurelec and Rijavec (1966) and Isseroff et al. (1972) have shown that free proline makes up 25 to 30% of the total free amino acid nitrogen in the trematode, Fasciola hepatica. In the latter study an increase in the total free amino acid concentration was observed in the bile of infected animals. While most free amino acids increased by approximately 40 times normal concentration, proline exhibited the greatest change in concentration with increases up to 10,000-fold. Because an increase of this magnitude in a single amino acid was likely to be of significance in the host-parasite relationship, it was of interest to determine the origin of the excessive proline. From data in the study cited above (Isseroff et al., ibid.) it was known that the concentration of proline in the worm itself was always greater than in the bile, while analysis of host tissues revealed proline in concentrations as low as those in uninfected controls. Yet it was not likely that the worms were concentrating proline from the bile. Studies by Isseroff and Read (1969) had shown that proline uptake by the worm in 2min incubations is a linear function of increasing concentration, indicating uptake by simple diffusion. Furthermore, Moss (1970) observed that proline was one of the major free amino acids excreted by Fasciola in in-vitro

Effects of Schistosoma mansoni on androgen regulated gene expression in the mouse.

Two-dimensional gel electrophoresis of liver mRNA translation products and dot-blot hybridization revealed that the levels of mRNA encoding major urinary proteins were greatly reduced in mice infected with Schistosoma mansoni. Major urinary protein mRNA levels are known to be androgen regulated. Dot-blot hybridization analysis of RNAs from various mouse tissues with a variety of cDNA probes indicated that all androgen-regulated mRNAs tested were reduced in infected mice. Administration of testosterone to infected animals restored urinary major urinary protein levels. Direct measurement of serum testosterone levels and seminal vesicle weights confirmed that chronic schistosome infection reduces testosterone to castration levels in male mice.

Schistosomiasis: Role of endogenous opioids in suppression of gonadal steroid secretion

1. Radioimmunoassay of the opiate, beta-endorphin, in mouse sera, indirect measurement of estrogen by examination of vaginal smears and indirect measurement of androgens by electrophoresis of major urinary proteins (MUP) revealed that beta-endorphin increases while estrogen and androgen levels decrease in mice with chronic Schistosoma mansoni infection. 2. Injections of the opiate antagonist, naltrexone, reversed the effects of schistosomiasis on estrogen and androgen levels. 3. Because opiates are known to inhibit the secretion of releasing hormones by the hypothalamus, the data suggest that the inhibition of hypothalamic-pituitary-gonadal function that occurs in chronically infected male and female mice results from excessive beta-endorphin. 4. It is also suggested that the excessive beta-endorphin may be secreted by T-lymphocytes and possibly macrophages involved in the cell-mediated immune response (CMIR) to the ova.

Monosaccharide absorption by Schistosomamansoni—I. Kinetic characteristics☆

Abstract 1. 1. Absorption kinetics of fructose, galactose, glucosamine, glucose, ribose, β-methylglucoside, and 3-0-methylglucose were measured. 2. 2. All the above sugars except β-methylglucoside are absorbed by a facilitated diffusion process. 3. 3. Only glucose and glucosamine appeared to be accumulated by the worms. However, most of the glucose was metabolized during uptake. 4. 4. The effects of various physical and chemical factors on absorption indicate that the process is similar to that in the liver fluke, Fasciola hepatica.

Fascioliasis: bile duct collagen induced by proline from the worm.

We investigated whether collagen increases occur in the bile duct during fascioliasis, and their relationship to the release of proline by the worm. Experiments showed increased levels of collagen in the bile ducts of rats following 2 wk of infusion with proline or i.p. implantation with Fasciola. The increase in bile duct collagen in proline-infused animals and in worm-implanted animals could be completely inhibited to the amount in controls by 3,4-dehydroproline. These effects suggest that the hyperplasia of the bile duct that is induced by liver flukes involves stimulation of collagen deposition through their release of proline.

Proline in fascioliasis—IV induction of bile duct hyperplasia

Abstract 1. 1. Rats were implanted with cannulae in the abdominal cavity and infused with one of the following solutions: saline; 20.0 mM proline in saline, or saline containing alanine, valine, methionine, leucine, tyrosine, phenylalanine and histidine each at 2.0 mM. 2. 2. Comparison of the lumenal perimeters in the bile ducts of the infused animals revealed that a significant hyperplasia was induced by proline; none of the other amino acids tested was effective. 3. 3. Histologically, the proline-induced hyperplasia resembles that observed in bile ducts from rats infected with Fasciola hepatica.

Bile duct hyperplasia in mice infected with Schistosoma mansoni

Schistosoma mansoni releases large amounts of proline into the hepatoenteric circulation. Because proline release has been linked to bile duct hyperplasia in fascioliasis, the current investigation tested the possibility that such hyperplasia might occur in schistosomiasis. The lumenal perimeter and wall thickness in bile ducts was compared between infected and uninfected mice. In those harboring 5 week old S. mansoni infections there was a 180% increase in the lumenal perimeter of the duct (P<0.001) and a 580% increase in the thickness of the duct wall (P<0.001). These results tend to support data linking proline to bile duct and liver fibroblast proliferation.

Fascioliasis: similarities of the anemia in rats to that produced by infused proline.

Fasciola hepatica releases large amounts of proline into the bile of its host. Significant increases in the levels of other amino acids in the bile also occur. The present investigation examines whether proline and these other amino acids may play a role in inducing the anemia that frequently accompanies fascioliasis. In experiments, rats were infused intra-abdominally for 2 weeks with 1 of 3 solutions: 20.0 mM proline in saline, a mixture of 8 amino acids (excluding proline) each at 2.0 mM in saline, or saline only. At the end of the experiments 2 cc of blood was removed from each rat, via cardiac puncture. The heparinized blood was used to count erythrocytes and reticulocytes, and to measure hematocrit and mean corpuscular volume (MCV). Analysis of variance disclosed highly significant differences in erythrocyte counts, MCV, and reticulocyte counts among the 5 groups. A Student-Newman-Keuls test indicated that the Proline and Infected groups were not different from each other (except for MCV, where prolines effect was more severe) and that both groups differed significantly from the Amino Acid group, the Saline group, and the Control group. Hence, it appears that infused proline can cause an anemia similar to that induced by Fasciola.

Fasciola hepatica: Bile duct enlargement induced in rats after intraperitoneal transplantation

Abstract Adult Fasciola hepatica were placed in fine mesh sacks and implanted into the abdominal cavity of rats. After 3 weeks the main bile ducts from these animals were removed and transverse sections were prepared using standard procedures for light microscopy. The perimeter of the bile duct lumen was then measured and statistically compared to the lumenal perimeter of bile ducts from rats which were implanted with sacks lacking worms. The results indicated that the bile duct perimeter in rats with five or more implanted worms surviving after 3 weeks was nearly twice that of the sham transplants. Futhermore, the histology of the ducts from rats with transplanted worms resembled that observed in rats at 20–40 days after oral infection. Because the sacks prevented physical contact between the worms and the bile duct or liver, these results suggest that the hyperplasia of the biliary tract in fascioliasis is induced by a chemical factor.

Levels of type I and type III collagen in the bile duct of rats infected with Fasciola hepatica

Collagen types and their levels were compared between bile ducts from Fasciola infected rats and bile ducts from uninfected animals. Both collagen types I and III were shown to be increased in infected animals but, levels of type I increased less than type III. These results indicate that fascioliasis produces changes in the collagen composition of the bile duct that are similar to those produced in cirrhosis of the liver and other pathologic conditions including wound healing. Such observations suggest that a study of the chronology of collagen deposition in fascioliasis might provide information on the sequence of molecular events which result in bile duct hyperplasia.