Characterization of a Schistosoma mansoni gene encoding a homologue of the Y-box binding protein

Hematopoietic stem cells (HSCs) support blood cells throughout life by utilizing their self-renewing and multilineage differentiating capabilities. Hematopoietic growth factors mediate their effects on stem cells by the tyrosine phosphorylation of proteins. Regulation of tyrosine phosphorylation is partially mediated by protein tyrosine phosphatases (PTPases). A possible mechanism by which hematopoietic stem cells maintain their self-renewing capacity and undifferentiated state is by controlling the balanced and opposing actions of protein tyrosine kinases (PTKs), receptors for growth factors, and PTPases. We have characterized the expression of PTPases in 5-fluorouracil (5-FU)-treated murine bone marrow cells, which represent a very primitive population of progenitors enriched for reconstituting stem cells, by using a consensus polymerase chain reaction (PCR) method. Several PTPases were expressed abundantly in the 5-FU-treated bone marrow stem cells. A novel PTP, termed protein tyrosine phosphatase receptor omicron (PTPRO), which is related to the homotypically adhering kappa, mu and PCP-2 receptor-type tyrosine phosphatases, was identified and characterized. We have cloned the murine and full-length human PTPRO cDNAs which share 89% homology, indicating that PTPRO is highly conserved between these species. The human PTPRO cDNA clone encodes a polypeptide of 1439 amino acids (aa) and has a calculated molecular mass of approximately 162 kDa. PTPRO consists of an extracellular segment containing a MAM domain, an immunoglobulin (Ig) domain, four fibronectin-type III (FN-III) repeats, a transmembrane segment, and two tandem intracellular PTP domains. The human PTPRO gene was assigned to human chromosome 1p35-pter using Southern blot analyses of genomic DNAs from rodent/human somatic hybrid cell lines containing human chromosome 1 or the p35-pter region of the chromosome. The mouse Ptpro gene was mapped to chromosome 4, closely linked to D4Mit16 and Elp1 (elliptocytosis-1), by using genomic DNAs from a (C57BL/6J x Mus spretus)F1 x Mus spretus backcross. In fetal tissues, PTPRO expression was observed in the brain and lung, whereas lower levels were observed in the kidney. In adult tissues, PTPRO was less restricted and was observed in the lung, heart, skeletal muscle, prostate, testis, and in various areas of the brain, indicating that PTPRO expression is developmentally regulated. Expression of PTPRO was also observed in human CD34+ bone marrow cells and 5-FU-treated murine primitive stem cells. These results suggest a potential role for PTPRO in stem cell adhesion and in mediating homophilic cell-cell interactions in other cell types.     

Studies on experimental mixed infection of Schistosoma haematobium and Schistosoma mansoni

Swiss Albino mice have been infected with S. haematobium and challenged 4 weeks later with S. mansoni. Parasitological, pathological and ultrastructural studies were done. The results revealed cross mating between the two species. A reduction in S. mansoni worm load, egg count, hepatic granuloma number and size was noticed. The presence of heterologous immunity was suggested.     

Evidence for ryanodine receptors in Schistosoma mansoni

The present study investigated the presence of ryanodine receptors in the trematode Schistosoma mansoni. [3H]Ryanodine specific binding sites were found in the four subcellular fractions of S. mansoni; however, more binding sites were recovered in the heterogeneous fraction P1 and the microsomal fraction P4, as was thapsigargin-sensitive (Ca2+-Mg2+)ATPase activity, marking the sarco/endoplasmic reticulum calcium ATPase (SERCA) pumps. This binding had an equilibrium dissociation constant (Kd) in the nanomolar range, an apparent maximal number of receptors (Bmax) of about 80 fmol/mg of protein, and was modulated by ions (Ca2+, Mg2+) and some pharmacological tools such as caffeine. Ryanodine was able to accelerate the rate of 45Ca2+ release from actively loaded vesicles, and also to induce a transient contraction of the whole worm. We conclude that ryanodine-sensitive Ca2+ release channels are present in S. mansoni, with properties very similar to the ones present in higher animals.     

Characterization of a Schistosoma mansoni cDNA encoding a B-like cyclophilin and its expression in Escherichia coli

A cDNA encoding a Schistosoma mansoni cyclophilin (SmCyP) has been cloned by polymerase chain reaction amplification using degenerate oligonucleotides based on known conserved cyclophilin (CyP) sequences and by screening an expression cDNA library. The cDNA sequence encodes a 21.5-kDa protein, which shares 59% sequence identity with human CyP B. The SmCyP protein was expressed in Escherichia coli with a hexahistidine affinity tag at its amino terminus and antibodies to the purified (His6)-SmCyP fusion protein were raised in a rabbit. Fractionation of parasite material followed by immunoblot analysis revealed that schistosome CyP is a soluble protein. The N-terminus of the predicted protein contains a hydrophobic region, suggestive of a signal sequence. Accordingly, a recombinant SmCyP protein, lacking the first 23 amino acids was found to share the same gel electrophoretic mobility as the parasite-derived CyP protein, suggesting cleavage of a leader sequence. Hybridization of genomic DNA to a full-length cDNA probe indicates that the SmCyP gene is present as a single copy. Immunohistological experiments in conjunction with confocal scanning laser microscopy and immune electron microscopy show that SmCyP is present in abundance in the adult worm as well as in the schistosomula. The function of CyP in the schistosome is presently unclear, but since its ligand, cyclosporin A, has antischistosomal activity, its function is expected to be a vital one.     

Recombinant human interleukin-1-mediated killing of Schistosoma mansoni primary sporocysts in Biomphalaria glabrata

Previous work has indicated that injection of recombinant-human interleukin (rhIL)-1beta in Schistosoma mansoni-infected M-line Biomphalaria glabrata resulted in a significant reduction in the number of cercariae shed. The purpose of the present work was to determine if primary sporocysts were killed following rhIL-1beta injection in susceptible snails and, if so, to determine if killing was the direct result of hemocyte activity. Counting of primary sporocysts indicated a 50% reduction in the number surviving at 3 days PE in snails from 2 susceptible strains following injection. Histological analysis indicated that killing occurred with little-to-no observable hemocyte/parasite contact, whereas short-term culture of primary sporocysts with cell-free plasma (hemolymph) from injected snails rapidly initiated killing in vitro. Because levels of a snail IL-1-like molecule (SnaIL-1) drop significantly following schistosome exposure in M-line snails, because resistant snails maintain higher SnaIL-1 levels following infection, and because rhIL-1beta upregulates hemocyte cytotoxic mechanisms, these data support the contention that SnaIL-1 plays a role in determining resistance in B. glabrata. These data also indicate that schistosome death may be separated from parasite encapsulation by hemocytes and that an as yet unidentified humoral killing mechanism/factor may exist in B. glabrata. Lastly, these data further support the hypothesis that cytokine-like molecules are important, functionally conserved immunodefense mediators in both vertebrates and invertebrates.     

Features of Schistosoma mansoni infection in SCID mice

Features of Schistosoma mansoni infection in SCID mice, which lack functional T- and B-lymphocytes, were investigated. The retarded development of parasites as well as reduction of liver egg recovery in SCID mice was significantly lower than those in congenic counterpart C.B-17 mice. Furthermore, the rate of parasite recovery from SCID mice with primary infection was always lower than that from C.B-17 mice by 20%, showing the innate resistance to S. mansoni infection. SCID mice vaccinated with UV-attenuated S. mansoni cercariae did not show protective immunity against a homologous challenge infection. The present innate resistance exhibited in SCID mice is discussed in relation to cell mediated immunity of macrophage activation by IFN-gamma which would not involve T-lymphocytes but is initiated by IL-12 and TNF-alpha cytokines. SCID mice may provide novel information on the host-parasite relationship in schistosome infections.     

Tegument changes of Schistosoma japonicum and Schistosoma mansoni in mice treated with artemether

AIM: To study the effect of artemether (Art) on the tegument of schistosomes. METHODS: Mice infected with S japonicum cercariae for 7 and 35 d, or with S mansoni cercariae for 49 d were treated intragastrically with Art 200-300 mg.kg-1.d-1 for 2 d. Schistosomes were collected in groups of 2 mice at various intervals after medication for scanning electron microscopic observation. RESULTS: The tegumental changes induced by Art appeared to be similar in S japonicum and S mansoni: swelling and fusion of tegumental surfaces, vesicle formation and collapse of discoid-like sensory structures. In S japonicum the emergence of tegumental alterations was earlier in 7-d-old schistosomulae than that in 35-d-old adult worms. CONCLUSION: Art injured the teguments of S japonicum and S mansoni.     

HPLC fractionated soluble egg antigen from Schistosoma mansoni elicits a heterogeneous human immune response

Antihypertensive effects of beni-koji were studied using 29 outpatients with mild hypertension in a placebo-controlled double-blind comparative fashion. After a 4-week vehicle (apple juice) run-in period, 13 patients were assigned to receive beni-koji aqueous extracts containing juice once daily (27 g of beni-koji eq. per day) for 8 weeks and 16 were assigned to vehicle. Two patients assigned to the vehicle group did not complete the study. In addition to casual blood pressure, 24-hr non-invasive ambulatory blood pressure (ABP) was monitored in 6 patients given the beni-koji drink and 5 patients given the vehicle. 1) In the beni-koji group, both casual systolic and diastolic pressure decreased significantly during the treatment period (from 150 +/- 10/96 +/- 6 mmHg to 140 +/- 10/89 +/- 10 mmHg, p < 0.01). The averages of the 24-hr blood pressure recorded in ABP (24-BP) also significantly decreased (from 141 +/- 17/95 +/- 13 mmHg to 132 +/- 21/86 +/- 10 mmHg, p < 0.05) when compared with those of the control period. Casual pressure normalized (less than 140/90 mmHg) in 4 patients who received beni-koji. Circadian variation of the blood pressure by ABP showed a significant decrease during the daytime. 2) In the vehicle group, casual systolic pressure did not change significantly (from 155 +/- 8 mmHg to 151 +/- 12 mmHg), but diastolic pressure decreased significantly (98 +/- 7 mmHg to 93 +/- 6 mmHg). Casual blood pressure did not normalize in any of the patients and 24-BP did not change significantly. 3) Summative evaluation of safety showed that no problems appeared in the beni-koji group. In conclusion, beni-koji appears to be an effective and safe food material for mild essential hypertension. The mechanism of the antihypertensive effect of beni-koji still remains to be investigated.     

Cercaria chaetotaxy of 2 Venezuelan strains of Schistosoma mansoni

By means of the silver impregnation of two lots of Schistosoma mansoni cercariae belonging to the strains: JR (32 cercariae) and C5 (45 cercariae), the number and pattern of disposition of the argentophillic papillae were determined with the following results: Average number of total dorsal papillae: 12.1 (JR strain) and 12.0 (C5 strain); the variation coefficients in this surface were less than 4% (JR strain) and bigger in JR than C5 strain. Average number of total ventral papillae: 12.15 (JR), 11.97 (C5); maximum value of the variation coefficient: 6.4% (JR), higher in JR than C5 strain. When the ventral surface was classified in four quadrants, the average number of papillae by quadrant was: quadrant A: 1.15 (JR) and 1.06 (C5): B: 1.06 (JR) and 1 (C5); C: 4.97 (JR) and 4.96 (C5); D: 5.03 (JR) and 4.98 (C5). The variation coefficients were higher in the A and B ventral quadrants, reaching maximum values of 31.9%, and 61.0% for the posterior quadrants C and D. When the ventral surface was divided in three equal parts for determining the position of the most variable papillae of this area, the greatest value of the variation coefficients obtained were for the 2nd thirds of the cercariae: 89.8% and 76.8% for C5 strain and 43.5% and 56.8% for JR strain. In relation to the total lateral papillae, the average numbers were: 17.0 (JR) and 16.6 (C5), with a maximum value of variation coefficient of (8.1% (C5). The average total number of papillae of the tail were: 25.6 (JR) and 26.1 (C5) for the ventral surface and 20.72 (JR) and 21.33 (C5) for the dorsal papillae. The comparison between the percents of the cercariae of two S. mansoni strains with more than 1 papillae on the anterior ventral quadrants A or B (94% JR and 34% C5), resulted with significant differences (P < 0.05).     

Pairing of Schistosoma mansoni males in infected Syrian hamsters

Pairing of male schistosomes in the liver of infected hamsters was recorded with Egyptians S. mansoni strain. The homospecific male pairs never carried each other in the gynaecophoric duct, but they being closed in either central or hepatic veins. Other perfused males and females en copula showed normal mating behaviour. The paired males were more or less in the same size. The random sexed miracidia used resulted in obtaining 1:2.1 female/male ratio. It is concluded that the random increase of male schistosomes may create the male pairing behaviour. Also, the migration of female against the blood stream to the mesenteric plexus of the host and the failure of male to catch them may lead to this homosexual pairing. The black haemozoin-like substance seen in mature females was also observed in the pairing males and this probably reflects the effect of scarcity or migration of females to the mesenteric plexus.     

Tissue reactions induced by Schistosoma mansoni in Biomphalaria glabrata

In Biomphalaria glabrata with a strong natural resistance, Schistosoma mansoni sporocysts are rapidly encapsulated by granulocytes and killed, mainly by the strong phagocytic activity of the cells. Irradiated Echinostoma paraensei sporocysts seem able to suppress the function of the granulocytes. Tissue reactions in snails with self-cure demonstrate: involvement of two types of cells, granulocytes and hyalinocyte-like cells; formation of amoeba-fibrous capsules; limited tendency of granulocytes to become attracted to the parasites; a slow process of parasite destruction; and a possible involvement of humoral factors. It seems that there is partial suppression of the granulocyte function in smails with self-cure.     

Biology and pathology of Schistosoma mansoni and Schistosoma japonicum infections in several strains of nude mice

Schistosoma mansoni and S. japonicum infections in nude mice (nu/nu) were compared with infections in nu/+ heterozygotes or intact mice. Seven to 12 weeks after exposure to S. mansoni, the responses of Swiss NCR, C3H, BALB/c and C57B1/6 nude mice did not differ substantially. Nude mice of all these strains showed minute granulomas around eggs in the liver and minimal hepatic fibrosis. Microvesicular and necrotizing changes in hepatocytes were similar in all mouse strains, and S. mansoni infections were frequently lethal to nude, but not to intact mice between the seventh and ninth weeks of infection. Nude mice that survived the ninth week of infection generally lived until the 12th week. The number of eggs per mature worm pair in the tissues of S. mansoni-infected nude mice was similar to the number in intact mice, but nude mice passed fewer eggs in the feces. Nude mice that received serum from infected intact mice excreted eggs in the stool in numbers equivalent to intact mice, but continued to form minute granulomas around S. mansoni eggs. Reconstitution with fetal thymus or with splenocytes from normal or S. mansoni-infected mice partially or completely restored hepatic granuloma size, granuloma eosinophils, hepatic fibrosis, and excretion of eggs in the feces. In contrast to S. mansoni infection, S. japonicum infections in nude mice did not cause necrosis of hepatocytes or excessive mortality, and S. japonicum eggs were passed in the feces in numbers equivalent to those passed by infected intact mice.     

Cloning and characterization of a Schistosoma mansoni cDNA clone with a specific antigenic expression during development in a vertebrate host

Approximately 2.0 x 10 cDNA clones of an Schistosoma mansoni lambda gt11 cDNA library were screened in duplicate with serum from infected mice corresponding to distinct phases of infection. A cDNA clone (7/1) was isolated and recognized only by seven week serum. The clone was subcloned in pGEX-2T and Western-blot studies showed a specific antigenic expression confirming that only serum from the chronic phase is capable of recognizing this antigen. Dot-hybridization with RNA from different developmental phases of the parasite showed that the corresponding 7/1 RNA is expressed in all phases of parasite development in vertebrate hosts.     

Dermal endothelial cells and keratinocytes produce IL-7 in vivo after human Schistosoma mansoni percutaneous infection

The parasite Schistosoma mansoni infects its definitive mammalian host through an obligatory cutaneous penetration. In this work, we studied early immune response following migration of larvae through human skin, the first immunocompetent organ encountered by the parasite. For this purpose we used an experimental model of severe combined immunodeficient mice engrafted with human skin and injected with autologous PBL. Six days after percutaneous infection, we observed an infiltration of lymphocytes within the human skin, predominantly composed of CD4+ T cells. Moreover, among the cytokines potentially present in the infected skin, immunohistochemistry analysis revealed an in vivo expression of IL-7 in the epidermal layers and strikingly at the level of vascular endothelium. Using an in vitro coculture system, we showed that the S. mansoni larvae directly trigger IL-7 production by human dermal microvascular endothelial cells but not by keratinocytes. Finally, measurements of IL-7 concentrations in plasma of 187 S. mansoni-infected individuals showed that the youngest, which are also the most infected, displayed the highest IL-7 levels. Together, these findings describe dermal endothelial cells as a novel source of IL-7, a cytokine particularly important in schistosomiasis.     

Hatching of Schistosoma mansoni eggs and observations on motility of miracidia

Eggs of Schistosoma mansoni were obtained from livers of mice and hatching was observed under varying conditions of light and ionic composition of the medium. Hatching occurred equally well in light and in darkness. Eggs also hatched readily in 1- to 50-m OsM solutions of urea, sucrose, sodium chloride, and glycerol, but hatching was inhibited at higher concentrations unless the eggs were left in solutions for long periods of time. Hatching readily occurred in deionized water, but the emerged miracidia did not swim longer than 5 to 10 min unless Na+ was added. Histochemistry of the egg showed DNA-positive egg granules and a polysaccharide-positive vacuole matrix. Acid mucopolysaccharides were stained in the vacuolar matrix and in the anterior sac of the miracidium. Longitudinal alignment of constituents of the egg shell is suggested by the predominance of longitudinal rents in the shell at hatching. A mechanism of hatching involving an osmotic stimulus is proposed.     

A study of the relationship between temperature and the infectivity of Schistosoma mansoni and Schistosoma haematobium cercariae

An unusual form of left ventricular aneurysm affecting young Negroes has recently been described at the aortic or mitral valve ring; constitutional factors have been postulated. A 4-year-old Negro boy was observed with a left ventricular submitral aneurysm, probably one of the largest and one of the most calcified to be reported. Tuberculous lymphadenitis involving some of the mediastinal lymph nodes was found on postmortem examination; tuberculosis was believed to be a secondary contributing factor. A review of the literature disclosed only 5 other children with calcified left ventricular aneurysms, of which 2 were of the subvalvular type.     

Immunizing potential of ultraviolet-attenuated cercariae of Schistosoma mansoni in rodent hosts

This article studies how two diagnostic tests (cytological puncture and 201thallium scanning) can be combined to obtain a more efficient approach of cold thyroid nodules. Diagnostic and therapeutic approaches are compared on the basis of four criteria: financial cost (immediate and delayed), number of labelled cancers, pre- and postoperative death rates and number of complications.     

Effect of praziquantel on the free living stages of Schistosoma mansoni

The effect of the new schistosomicide praziquantel (2-cyclohexyl-carbonyl-1,2,3,6,7,11 b-hexahydro-2H-pyrazino[2,1a]isoquinolin-4-one) on the miracidia and cercariae of Schistosoma mansoni was investigated. In vivo praziquantel inhibits hatching of miracidia for 24 h after administration of 500 mg/kg to infected mice. In vitro a concentration of 10 microgram/ml inhibits subsequent hatching in drug-free water. Free swimming miracidia are rapidly killed by 1 microgram/ml. Even 0.01 microgram/ml is still partially effective. In a solution of 0.03 microgram/ml cercariae lose their ability to swim within 10 min. This effect is reversible in drug-free water. Morphological damage to cercariae incubated in 0.1 microgram/ml is clearly evident. However, cercariae are fully infective when given subcutaneously to mice after a 3-h incubation period. Incubation in 1 microgram/ml reduces the infection rate by 80%. A 2-h incubation in 0.1 microgram/ml almost completely inhibits the percutaneous infection through the abdominal skin. The number of cercariae that develop to schistosomules is reduced by more than 90%. After a 2-h incubation in a concentration of 0.01 microgram/ml the swimming ability of cercariae is impaired in such a way that the number of cercariae penetrating in the tail immersion test and developing to schistosomules is reduced by half. Praziquantel is a more potent protective agent than the molluscicides copper sulphate, sodium pentachlorophenate and Bayluscide or cadmium and zinc ions.