Expression and characterization of glutathione peroxidase activity in the human blood fluke Schistosoma mansoni.

Antioxidants may play an important role in immune evasion by schistosome parasites. Previous studies have focused on the roles of superoxide dismutase and glutathione S-transferase. In the present study, glutathione peroxidase (GPX) activity was measured in different fractions of worm extracts from several developmental stages of Schistosoma mansoni. The enzyme activity was shown to be developmentally regulated, with higher specific activities being found in the tegument-enriched Nonidet P-40 extract of adult worms (the stage least susceptible to immune killing) than in the larval stages (which are most susceptible to immune elimination). In all extracts tested, the activity against cumene hydroperoxide, even when glutathione S-transferase activity was removed, was higher than that for hydrogen peroxide. The expression of GPX cDNA in pGEX-2T by bacteria produced a 50-kDa fusion protein and a 32-kDa truncated protein. The latter was due to termination at the internal UGA codon that codes for selenocysteine. GPX activity was detected in the recombinantly produced GPX but not with Sj26-glutathione S-transferase from the vector. Mutating the TGA codon to TGT produced a full-length product, GPXm (19 kDa), that was used to produce 19 monoclonal antibodies. Anti-GPXm monoclonal antibodies recognized a 19-kDa molecule in adult-worm extract which, upon removal by immunoprecipitation, resulted in the loss of over 90% of the GPX activity, suggesting that a single form of GPX exists in the schistosome.     

Comparison of the cloned genes of the 26- and 28-kilodalton glutathione S-transferases of Schistosoma japonicum and Schistosoma mansoni.

Both Schistosoma japonicum and S. mansoni contain 28- and 26-kDa glutathione S-transferases (GSTs). Despite their immunological cross-reactivity using rabbit antisera, the S. japonicum 28-kDa GST (Sj28) is weakly immunogenic relative to the S. mansoni protein (Sm28) in mouse immunization experiments using GSTs purified from adult worms. The difference in immunogenicity is also observed during schistosome infection in mice. Using surface-labeled living S. japonicum worms, evidence was obtained for a surface location of Sj28 comparable to that reported for the S. mansoni molecule. The nucleotide and deduced amino acid sequences of cDNA clones corresponding to Sj28 and Sm28 were compared. Despite obvious homology (77% identity), differences were found in regions known to contain T epitopes in the S. mansoni protein which may be an explanation for the striking differences in immunogenicity in regard to antibody production in mice. The 26-kDa GSTs of these two parasites (Sj26 and Sm26) are also closely related on the basis of nucleotide and deduced amino acid sequences, there being 82% identity in the putative coding regions. When the amino acid sequences of Sj28 and Sm28 were compared with those of Sj26 and Sm26, the overall sequence identity was approximately 20%. However, a relatively conserved region was identified in otherwise structurally different molecules which may participate in common properties of these enzymes.     

Molecular cloning and tissue distribution of a 26-kilodalton Schistosoma mansoni glutathione S-transferase

A Schistosoma mansoni cDNA library was constructed from the mRNA of adult worms in the expression vector lambda gt11 and screened with a rabbit antiserum raised against the 26-kDa S. mansoni glutathione S-transferase isoforms (Sm GST 26). Two clones were selected and the nucleotide sequences deduced. The predicted amino acid sequence, specified by these cDNAs, shows strong homology with a Schistosoma japonicum 26 kDa glutathione S-transferase and a lower level of homology with mammalian glutathione S-transferase class mu isoenzymes (EC 2.5.1.18). No significant homology score was found with a 28-kDa S. mansoni glutathione S-transferase (Sm GST 28). A study of the tissue distribution of the cloned Sm GST 26 by immunoelectron microscopy shows similarities to Sm GST 28 in that they are present in the tegument and in subtegumentary parenchymal cells. However, a major difference exists in the protonephridial region in which Sm GST 26 is present in the cytoplasmic digitations localized in the apical chamber delineated by the flame cell body, suggesting that Sm GST 26 may be actively excreted by adult worms.     

Expression and purification of glutathione S-transferase-tagged HIV-1 gp120: no evidence of an interaction with CD26

We describe the use of a new baculovirus expression vector to enable the secretion of the major surface glycoprotein of HIV-1 (gp120) fused to the carboxy-terminus of the widely used affinity tag glutathione S-transferase. The secreted protein can be purified in a single step with the minimum of denaturation on immobilised glutathione and is as active as the parental molecule in binding CD4. We use this molecule in a variety of assay formats to examine the gp120 interaction with CD26, a reported auxiliary molecule in the HIV entry process. We find no evidence of a CD26-gp120 interaction in the absence or presence of CD4.     

Inter-species variation of schistosome 28-kDa glutathione S-transferases.

The 28-kDa glutathione S-transferase from Schistosoma mansoni (Sm28GST) is a candidate vaccine antigen. To evaluate the antigenic and phylogenetic variations between the 28-kDa GSTs from 4 species of schistosome, we have cloned and sequenced the 28-kDa GSTs from Schistosoma haematobium (Sh28GST) and Schistosoma bovis (Sb28GST). Sb28GST and Sh28GST are more similar to each other (97%) than to Sm28GST (90%) and particularly to the 28-kDa GST from Schistosoma japonicum (Sj28GST, 77%). Antisera directed against the major Sm28GST epitopes revealed differences in the recognition of the 28-kDa GSTs from the other schistosome species suggesting that these regions have been subjected to evolutionary pressure. The consequences of such species-specific epitopes on the development of a multi-species anti-schistosome vaccine are discussed.     

Different tissue responses of mixed function oxidases and detoxifying enzymes to aflatoxin B1 administration in the rat.

The carcinogenic effects of aflatoxin B1 have been related to the formation of an active intermediate metabolite, an epoxide produced via the cytochrome P-450-mediated mixed function oxidase. The toxicity of this intermediate is dependent on metabolic transformations by enzymes such as aryl hydrocarbon hydroxylase, glutathione S-transferase and glutathione peroxidase. Like the mixed function oxygenase, these enzymes are inducible, and dependent on the action of specific drugs and inducers. The present study describes the effect of a single sublethal i.p. dose (6 mg/kg body wt) of aflatoxin B1 on the specific activities of microsomal demethylases, aryl hydrocarbon hydroxylase (AHH), glutathione S-transferase and glutathione peroxidase in rat liver, kidney, lung, brain and adrenals. The enzymes were assayed 24 h after the toxin treatment. Among the different tissues, only liver AHH showed an induction on toxin treatment whereas those of kidney and brain declined. Microsomal demethylase was also high in liver and low in kidney. However, no significant alteration was induced by aflatoxin B1 on glutathione S-transferase and glutathione peroxidase activities in the various tissues examined except the adrenals, which showed a significant increase. The present study revealed that the reaction sequence for metabolic transformation of aflatoxin B1 is more complex than foreseen from the activities of these inducible metabolite-transforming enzymes.     

Glutathione-S-transferase induces murine dermatitis that resembles human atopic dermatitis

Background The molecular and functional basis of allergen-induced inflammation seen in atopic dermatitis (AD) remains undefined. Objective The objective of this study is to establish a murine model to dissect the pathological mechanisms of inflammatory reactions leading to the development of AD. Methods An inbred strain of mice. BALB/c, when injected peritoneally with 30 μg of recombinant Sj26 protein (rSj26). a glutathione S-transferase of Schistosoma japonicum worm, developed systematic dermatitis 21 days after immunization. The pathology of the dermatitis was examined by histological evaluation and immunostaining. The immediate skin hypersensitivity was demonstrated by scrum transfer and skin test. Epicutaneous patch test was used to demonstrate the antigen-specific late phase response. Results Significant responses of rSj26-specific IgE were detected 2 weeks after immunization., and such changes paralleled formation of skin lesions. The diseased skin pathology showed inflammatory changes such as infiltration of mononuclear cells and eosinophils in the dermis and mild spongiosis in the epidermis. Numerous IgE bearing cells were also detected in the dermis. Peripheral blood showed eosinophilia at the same time. In addition, rSj26-specific positive skin test and epicutaneous patch test could be demonstrated in rSj26-sensitized mice. Conclusions These results suggest that rSj26 is capable of eliciting atopic dermatitis-like lesions in BALB/c mice. This can be a useful animal model for elucidating allergen-induced immune responses and the development of various therapeutic interventions of atopic dermatitis in humans.     

Further characterisation of the Schistosoma japonicum protein Sj23, a target antigen of an immunodiagnostic monoclonal antibody.

Sj23, the 23-kDa target antigen in Schistosoma japonicum adult worms of the hybridoma monoclonal antibody (mAb) I-134, has been identified and cloned from cDNA libraries, mAb I-134 has been successfully used in immunodiagnostic assays to detect S. japonicum infection in Philippine patients. Sequence analysis has shown that Sj23 is the homologue, with 84% amino acid identity, of Sm23, a 23-kDa molecule from S. mansoni worms previously described from our laboratory. The domain structures of Sj23 and Sm23 are strikingly similar to the human membrane proteins ME491, CD37, CD53 and TAPA-1, which may suggest a functional role for the schistosome molecules in cellular proliferation.     

Identification of a multispecific lipoprotein receptor in adult Schistosoma japonicum by ligand blotting analyses

A 43-kDa putative lipoprotein receptor (Sj43) of adult Schistosoma japonicum worms has been identified using ligand blotting techniques. Single and two dimensional electrophoretic analyses showed that Sj43 consisted of a single acidic polypeptide with multiple lipoprotein specificity. The molecule bound 125I-labelled low-density (apo-B), very low-density or high-density (apo-A and/or apo-C) lipoproteins from different mammalian hosts that are permissive to S. japonicum infection, but did not bind mouse apo-A containing lipoprotein. The binding of 125I-labelled lipoprotein to Sj43 could be inhibited by unlabelled human LDL, EDTA or Suramin, or by chemical modification of lipoprotein lysine or arginine residues. Sj43 was localised at the parasite's tegument and gut lining.     

Construction,purification, and evaluation of multivalent DNA vaccine against <Emphasis Type="Italic">Schistosoma japonicum</Emphasis>

DNA vaccine encoding a multivalent antigen is a novel approach of protective immunization. Four Schistosoma japonicum candidate antigen genes, glyceraldehyde-3-phosphate dehydrogenase (SjGAPDH), 23 kDa transmembrane protein (Sj23), 14 kDa fatty-acid binding protein (SjFABP) and 26 kDa glutathione-S-transferase (Sj26), are recombined into two pieces of fusion genes SjFABP.Sj23 and Sj26.SjGAPDH, respectively. Tetravalent DNA vaccine pVIVO2-SjFABP.Sj23/Sj26.SjGAPDH is constructed by co-expressing these two fusion genes. The super-coiled DNA vaccines for large-scale clinic application were purified by sequential chromatographies including group separation chromatography and affinitive chromatographies. The purified DNA vaccines were evaluated for in vivo and in vitro transfection assay. The immunoprotective properties of the different kinds of constructed DNA vaccines were appraised by pharmacological trials. The pharmacological trials results showed that tetravalent DNA vaccine has higher protective efficiency than other tested DNA vaccines.     

Polymorphisms in biotransformation enzymes and the risk for recurrent early pregnancy loss

An imbalance between phase I drug metabolizing enzymes and phase II detoxification enzymes may contribute to the development of pre-eclampsia. Polymorphic variants in the phase I enzyme, cytochrome P450 genes may lead to increased toxification, whereas polymorphisms in the phase II enzyme, glutathione S-transferase genes may result in impaired detoxification. Most abundant in placenta and decidua is glutathione S-transferase P1-1, which may therefore be of particular importance in reproduction. We studied the frequencies of polymorphic variants in those enzymes in 187 women with recurrent early pregnancy loss and in 109 women with an uncomplicated obstetric history. DNA was extracted and subsequently polymerase chain reaction based genotyping assays were used. chi(2)-Analysis and Fisher's exact test were used for statistical evaluation. The glutathione S-transferase P1b-1b genotype was found significantly more often in women with recurrent early pregnancy loss than in controls (12% versus 5%, P = 0.03), in particular in those who consumed coffee (P = 0.02) or smoked cigarettes (P = 0.04). Polymorphisms in other glutathione S-transferase and cytochrome P450 genes occurred equally frequently in cases and controls. In conclusion, the occurrence of the glutathione S-transferase P1b-1b genotype, leading to lower glutathione S-transferase Pi enzyme activity and consequently to impaired placental detoxification, may represent a risk factor for recurrent early pregnancy loss.     

Toxoplasmacidal activity of macrophages activated by recombinant major surface antigen (P30) of Toxoplasma gondii.

Recombinant major surface antigen (P30), which was produced as a glutathione S-transferase (EC 2.5.1.18) fusion protein of Toxoplasma gondii, was found to be able to activate macrophages to kill T. gondii in vitro. The macrophage activation was due to P30 in the fusion protein, not to glutathione S-transferase.     

GSTM1 tissue genotype as a recurrence predictor in non-muscle invasive bladder cancer

Tissue genotyping is more useful approach than using blood genomic DNA, which can reflect the effects of the somatic mutations in cancer. Although polymorphisms in glutathione S-transferase (GST) have been associated with the risk of bladder cancer (BC) development, few reports provide information about the prognosis of BC. We investigated glutathione S-transferase mu (GSTM1) and glutathione S-transferase theta (GSTT1) genotypes using genomic DNA from primary 165 BC tissue samples to assess the association with disease prognosis. DNA samples from tumor were analyzed by multiplex polymerase chain reaction (PCR). The results were compared with clinicopathological parameters. The prognostic significance of the GSTs was evaluated by Kaplan-Meier and multivariate Cox regression model. Kaplan-Meier estimates revealed significant differences in time to tumor recurrence according to the GSTM1 tissue genotype (P = 0.038) in non-muscle invasive bladder cancer (NMIBC). Multivariate Cox regression analysis also revealed that the tissue GSTM1 genotype (hazards ratio [HR]: 0.377, P = 0.031) was an independent predictor of bladder tumor recurrence in NMIBC. This identification of GSTM1 tissue genotype as a prognosticator for determining recurrence in NMIBC should prove highly useful in a clinical setting.     

Differential inhibition of rat hepatic glutathione S-transferase isoenzymes in the course of fascioliasis

The effects of a subclinical fascioliasis at various stages of its development (at week 3, 6 and 9 after infection by oral administration of 20 metacercariae of Fasciola hepatica) in rats were determined on the activity of enzymes involved in liver metabolism of glutathione and on the subunit pattern of cytosolic glutathione S-transferase. The parasitic pathology was ascertained by clinical observation of the rats and at autopsy. Hepatic microsomal cytochrome P-450 content was significantly decreased in infected rats by week 3 and 6 post-infection. Not correlatively, the catalytic activities of glutathione S-transferase towards 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene were significantly lowered in last stages of the experimental fascioliasis (by week 6 and 9 post-infection). These decreases were correlated to that of subunit 1 as determined by means of high-performance liquid chromatography of cytosolic proteins whereas subunit 6 could also be decreased. Fascioliasis did not alter cytosolic glutathione, glutathione reductase and glutathione peroxidase activities or plasma glutathione S-transferase activity accepting 1-chloro-2,4-dinitrobenzene as the substrate.     

谷胱甘肽S—转移酶异质性研究

本文以不同状态的大鼠肝细胞为对象,采用生化和病理学方法研究了谷胱甘肽S-转移酶(GST)的异质性。根据GST同工酶酶谱分忻、GST活性改变状况和GST同工酶表达活性的改变等结果,表明GST无论在正常状态或病理状态下均具有显著的异质性。     

Glutathione S-transferase pi gene methylation: the search for a molecular marker of prostatic adenocarcinoma

Glutathione S-transferase pi gene methylation has recently been described in prostatic adenocarcinoma. Aggregate data on 115 samples studied to date have found an 87% sensitivity and 92% specificity for prostate cancer diagnosis. The current literature about this new marker is herein summarized, and possible molecular mechanisms by which glutathione S-transferase pi may participate in prostatic carcinogenesis are reviewed. The possible clinical implications of this molecular alteration in the diagnosis of prostatic adenocarcinoma are also studied.     

Variations due to hyperoxia and ageing in the activities of glutathione S-transferase and NADPH-cytochrome c reductase

We have studied the influence of hyperoxia and ageing on the activities of NADPH-cytochrome c reductase and glutathione S-transferase in different rat organs. Lung glutathione S-transferase activity increases markedly in 5-day-old pups exposed to hyperoxia, as observed for the O2- scavenging enzyme, superoxide dismutase. The levels of NADPH-cytochrome c reductase increase as well but after a 3-day lag period. In the liver, there is a pronounced decrease of both activities in 24-month-old rats, but at 12 months the activity of glutathione S-transferase increases whereas that of NADPH cytochrome c reductase activity decreases with respect to 3 months. The pattern of variations with age of NADPH cytochrome c reductase is similar in liver and brain. However the behaviour of brain glutathione S-transferase parallels that of the liver enzyme only up to 12 months. Thereafter the brain activity is maintained at a high level. These observations open the possibility that the high glutathione S-transferase levels in the old rat brain might be involved in protection towards oxidative alterations during ageing.     

日本血吸虫重组质粒pET32α-Sj26GST—Sj32的构建及其在大肠埃希菌BL21（DE3）中的表达

目的构建日本血吸虫重组质粒pET32α-Sj26GST—Sj32,分析该质粒在大肠埃希菌BL21（DE3）中的表达情况。方法超声粉碎日本血吸虫成虫提取总RNA,通过RT—PCR扩增获得Sj26GST和Sj32抗原编码基因,然后采用基因拼接法（geneSOEing）剪接Sj26GST和Sj32,得到Sj26GST—Sj32融合基因,克隆至原核表达载体pET32α（＋）,构建重组质粒pET32α一Sj26GST—Sj32,转化人大肠埃希菌BL21（DE3）,经异丙基硫代-β—D．半乳糖苷（IPTG）诱导表达后用SDS—PAGE和Westem—blot对表达产物进行分析和鉴定。结果基因拼接法扩增出约1991bp的Sj26GST—Sj32融合基因;双酶切和PCR鉴定证实Sj26GST—Sj32融合基因成功插入pET32α（＋）中,SDS—PAGE分析显示表达产物为分子质量约82000Mr的重组蛋白．与预期结果一致,表达的蛋白约占菌体总蛋白的22％：Western—blot鉴定重组蛋白能被日本血吸虫感染的兔血清识别。结论成功构建了日本血吸虫重组质粒pET32α一Sj26GST—Sj32,该质粒在大肠埃希菌BL21中获得了高效融合表达,表达的融合蛋白具有特异的抗原一件     

Cloning and sequence of the gene for heat shock protein 60 from Chlamydia trachomatis and immunological reactivity of the protein.

We isolated and sequenced the gene for the chlamydial heat shock protein 60 (HSP-60) from a Chlamydia trachomatis genomic library by molecular genetic methods. The DNA sequence derived revealed an operon-like gene structure with two open reading frames encoding an 11,122- and a 57,956-Da protein. The translated amino acid sequence of the larger open reading frame showed a high degree of homology with known sequences for HSP-60 from several bacterial species as well as with plant and human sequences. By using the determined nucleotide sequence, fragments of the gene were cloned into the plasmid vector pGEX for expression as fusion proteins consisting of glutathione S-transferase and peptide portions of the chlamydial HSP-60. HSP-60 antigenic identity was confirmed by an immunoblot with anti-HSP-60 rabbit serum. Sera from patients that exhibited both high antichlamydial titers and reactivity to chlamydial HSP-60 showed reactivity on immunoblots to two fusion proteins that represented portions of the carboxyl-terminal half of the molecule, whereas fusion proteins defining the amino-terminal half were nonreactive. No reactivity with the fusion proteins was seen with sera from patients that had been previously screened as nonreactive to native chlamydial HSP-60 but which had high antichlamydial titers. Sera from noninfected control subjects also exhibited no reactivity. Definition of recognized HSP-60 epitopes may provide a predictive screen for those patients with C. trachomatis infections who may develop damaging sequelae, as well as providing tools for the study of immunopathogenic mechanisms of Chlamydia-induced disease.     

Genetic and functional analysis of Haemophilus somnus high molecular weight-immunoglobulin binding proteins

Haemophilus somnus immunoglobulin binding proteins (IgBPs) are virulence associated but only one (p76) has been genetically defined. We determined the nucleotide sequence of the 5'-flanking region of the p76 gene. This region had been identified as the coding region for a series of high molecular weight (HMW)-IgBPs. Analysis of the nucleotide sequence indicated the gene (immunoglobulin binding protein A, ibpA) encoding the HMW and p76 IgBPs comprised a single open reading frame of 12,285 base pairs (bp). The ibpA gene is flanked by an upstream ORF of 1758bp, designated ibpB. The predicted amino acid sequences of these two genes demonstrate similarity to virulence exoproteins and their transporter proteins that comprise a two-partner secretion pathway in various Gram-negative bacteria. Motifs associated with binding to mammalian cells were also identified within the sequence. Competitive inhibition studies implicated a putative heparin-binding domain in adherence to bovine endothelial cells. Expression plasmids for glutathione S-transferase (GST)-fused recombinant fragments covered amino acid residues 972-3201. IgG2 Fc binding studies identified fragment 972-1515 (GST-IbpA3) as an Fc binding peptide. This peptide and GST-IbpA5 (aa 2071-2730) reacted strongly with convalescent phase serum. In a small preliminary study, calves immunized with the purified GST-IbpA3 peptide were protected against an intrabronchial H. somnus challenge.