Bibhuti N. Singh

Trichomonas vaginalis Lipophosphoglycan Triggers a Selective Upregulation of Cytokines by Human Female Reproductive Tract Epithelial Cells

ABSTRACT Trichomonas vaginalis is one of the most common nonviral sexually transmitted human infections and, worldwide, has been linked to increased incidence of human immunodeficiency virus type 1 transmission, preterm delivery, low birth weight, cervical cancer, and vaginitis. The molecular pathways that are important in initiating host inflammatory and immune responses to T. vaginalis are poorly understood. Here we report interactions of human cervicovaginal epithelial cells with the most abundant cell surface glycoconjugate of the parasite, the T. vaginalis lipophosphoglycan (LPG). Purified LPG mediated the adhesion of parasites to human vaginal epithelial cells in a dose-dependent manner. Furthermore, T. vaginalis LPG (but not LPG from Tritrichomonas foetus, the causative agent of bovine trichomoniasis) induced a selective upregulation of chemotactic cytokines by human endocervical, ectocervical, and vaginal epithelial cells, which do not express Toll-like receptor 4/MD2. The T. vaginalis LPG triggered interleukin 8 (IL-8), which promotes the adhesion and transmigration of neutrophils across the endothelium, and macrophage inflammatory protein 3α, which is a chemoattractant for immune cells and is essential for dendritic cell maturation. These effects were dose dependent and sustained in the absence of cytotoxicity and IL-1β release and utilized, at least in part, a signaling pathway independent from the Toll-like/IL-1 receptor adaptor protein MyD88.

Endobiont viruses sensed by the human host - beyond conventional antiparasitic therapy.

Wide-spread protozoan parasites carry endosymbiotic dsRNA viruses with uncharted implications to the human host. Among them, Trichomonas vaginalis, a parasite adapted to the human genitourinary tract, infects globally ∼250 million each year rendering them more susceptible to devastating pregnancy complications (especially preterm birth), HIV infection and HPV-related cancer. While first-line antibiotic treatment (metronidazole) commonly kills the protozoan pathogen, it fails to improve reproductive outcome. We show that endosymbiotic Trichomonasvirus, highly prevalent in T. vaginalis clinical isolates, is sensed by the human epithelial cells via Toll-like receptor 3, triggering Interferon Regulating Factor -3, interferon type I and proinflammatory cascades previously implicated in preterm birth and HIV-1 susceptibility. Metronidazole treatment amplified these proinflammatory responses. Thus, a new paradigm targeting the protozoan viruses along with the protozoan host may prevent trichomoniasis-attributable inflammatory sequelae.

KINETOPLASTID MEMBRANE PROTEIN-11 (KMP-11) IS DIFFERENTIALLY EXPRESSED DURING THE LIFE CYCLE OF AFRICAN TRYPANOSOMES AND IS FOUND IN A WIDE VARIETY OF KINETOPLASTID PARASITES

An abundant 11-kDa membrane protein was purified from African trypanosomes by organic solvent extraction and octyl-Sepharose chromatography. This protein cross-reacts with monoclonal antibodies originally generated against the lipophosphoglycan-associated protein of Leishmania donovani. Immunoblot analysis showed that the 11-kDa molecule was present in a variety of species of kinetoplastids. It was found in several species and subspecies of African trypanosomes and was present in low amounts in bloodstream forms and in larger amounts in procyclic, epimastigote and metacyclic life cycle stages. Expression of the 11-kDa molecule rapidly increased during transformation from bloodstream forms to procyclic forms, paralleling expression of the major surface glycoprotein of Trypanosoma congolense, the glutamic acid/alanine-rich protein, an analogue of T. brucei procyclin. The molecule was present in procyclic trypanosome membranes at approximately 2 x 10(5)-1 x 10(6) molecules per cell, suggesting it may have an important role in parasite membrane organization and function. Amino-acid analysis of the trypanosome 11-kDa protein showed it had a different composition than that of its leishmania counterpart. Its wide distribution in kinetoplastids and its membrane disposition suggest a name for this class of molecules: kinetoplastid membrane protein-11 (KMP-11).

The Villain Team-Up or how Trichomonas vaginalis and bacterial vaginosis alter innate immunity in concert

Objectives Complex interactions of vaginal microorganisms with the genital tract epithelium shape mucosal innate immunity, which holds the key to sexual and reproductive health. Bacterial vaginosis (BV), a microbiome-disturbance syndrome prevalent in reproductive-age women, occurs commonly in concert with trichomoniasis, and both are associated with increased risk of adverse reproductive outcomes and viral infections, largely attributable to inflammation. To investigate the causative relationships among inflammation, BV and trichomoniasis, we established a model of human cervicovaginal epithelial cells colonised by vaginal Lactobacillus isolates, dominant in healthy women, and common BV species (Atopobium vaginae, Gardnerella vaginalis and Prevotella bivia). Methods Colonised epithelia were infected with Trichomonas vaginalis (TV) or exposed to purified TV virulence factors (membrane lipophosphoglycan (LPG), its ceramide-phosphoinositol-glycan core (CPI-GC) or the endosymbiont Trichomonas vaginalis virus (TVV)), followed by assessment of bacterial colony-forming units, the mucosal anti-inflammatory microbicide secretory leucocyte protease inhibitor (SLPI), and chemokines that drive pro-inflammatory, antigen-presenting and T cells. Results TV reduced colonisation by Lactobacillus but not by BV species, which were found inside epithelial cells. TV increased interleukin (IL)-8 and suppressed SLPI, likely via LPG/CPI-GC, and upregulated IL-8 and RANTES, likely via TVV as suggested by use of purified pathogenic determinants. BV species A vaginae and G vaginalis induced IL-8 and RANTES, and also amplified the pro-inflammatory responses to both LPG/CPI-GC and TVV, whereas P bivia suppressed the TV/TVV-induced chemokines. Conclusions These molecular host–parasite–endosymbiont–bacteria interactions explain epidemiological associations and suggest a revised paradigm for restoring vaginal immunity and preventing BV/TV-attributable inflammatory sequelae in women.

Clinical Isolates of Trichomonas vaginalis Concurrently Infected by Strains of Up to Four Trichomonasvirus Species (Family Totiviridae)

ABSTRACT Trichomonas vaginalis, which causes the most common nonviral sexually transmitted disease worldwide, is itself commonly infected by nonsegmented double-stranded RNA (dsRNA) viruses from the genus Trichomonasvirus, family Totiviridae. To date, cDNA sequences of one or more strains of each of three trichomonasvirus species have been reported, and gel electrophoresis showing several different dsRNA molecules obtained from a few T. vaginalis isolates has suggested that more than one virus strain might concurrently infect the same parasite cell. Here, we report the complete cDNA sequences of 3 trichomonasvirus strains, one from each of the 3 known species, infecting a single, agar-cloned clinical isolate of T. vaginalis, confirming the natural capacity for concurrent (in this case, triple) infections in this system. We furthermore report the complete cDNA sequences of 11 additional trichomonasvirus strains, from 4 other clinical isolates of T. vaginalis. These additional strains represent the three known trichomonasvirus species, as well as a newly identified fourth species. Moreover, 2 of these other T. vaginalis isolates are concurrently infected by strains of all 4 trichomonasvirus species (i.e., quadruple infections). In sum, the full-length cDNA sequences of these 14 new trichomonasviruses greatly expand the existing data set for members of this genus and substantiate our understanding of their genome organizations, protein-coding and replication signals, diversity, and phylogenetics. The complexity of this virus-host system is greater than has been previously well recognized and suggests a number of important questions relating to the pathogenesis and disease outcomes of T. vaginalis infections of the human genital mucosa.

Liphosphoglycan-like glycoconjugate of Tritrichomonas foetus and Trichomonas vaginalis

Lipophosphoglycan-like glycoconjugates were isolated, purified and partially characterized from Tritrichomonas foetus and Trichomonas vaginalis. Cell surface radiolabeling of both trichomonads by the galactose oxidase/NaB[3H]4 technique indicated that the glycoconjugate was located on the cell surface of the parasites. The glycoconjugates were extracted from the delipidated residue fraction with the solvent, water/ethanol/diethylether/pyridine/NH4OH (15:15:5:1:0.017) and were purified to homogeneity by Sepharose CL-4B followed by octyl-Sepharose chromatography and methanol precipitation. The glycoconjugates migrated as broad bands upon SDS-PAGE. The T. foetus glycoconjugate contained large amounts of fucose along with some mannose, galactose, glucosamine and glucose and trace amounts of galactosamine and inositol. The T. vaginalis glycoconjugate appeared to contain large amounts of glucosamine and galactose along with some glucose, mannose and traces of galactosamine and inositol. The surface-labeled glycoconjugates from both parasites was found to be deaminated with nitrous acid and susceptible to phosphatidylinositol-specific phospholipase C, indicating the presence of a phospholipid anchor. Furthermore, these glycoconjugate were found to contain phosphate and were labile to hydrolysis by mild acid, strongly suggesting that the intact molecule is related to Leishmania lipophosphoglycans (LPG). The most striking and the unique features of these glycoconjugate molecules are the presence of large amounts of fucose in T. foetus and glucosamine in T. vaginalis along with the presence of galactosamine in both parasites. These results indicate that these glycoconjugates are new types of LPG-like molecules expressed on the trichomonad cell surface and are structurally distinct from Leishmania LPG.

Di-O-alkylglycerol, mono-O-alkylglycerol and ceramide inositol phosphates of Leishmania Mexicana Mexicana promastigotes

Three acidic unsaponifiable lipid fractions were isolated by chromatographic methods from sandfly vector stages (promastigotes) of a protozoan parasite of man, Leishmania mexicana mexicana, cultured in vitro. Fast atom bombardment mass spectrometry, fast atom bombardment collision induced tandem mass spectrometry and metabolic labeling were used to characterize these lipids as di-O-alkylphosphatidyl-inositols, lyso-1-O-alkylphosphatidylinositols and inositol phosphosphingolipids. Molecular species of the dialkyl forms, new to natural product biochemistry, had a 20:0 substituent and either 17:1 or 18:1. The monoalkyl forms had either 17:0 or 18:0. The predominant ceramide had the 16:1 base and the lesser component the 16:0 base. In both, the N-acyl group was 18:0.

Fatty acid and sterol metabolism of cultured Trichomonas vaginalis and Tritrichomonas foetus

Trichomonas vaginalis and Tritrichomonas foetus grown in a fetal calf serum-based culture medium, contained as major lipids (i.e., greater than 10% of total) cholesterol, phosphatidylethanolamine and phosphatidylcholine. T. vaginalis also contained sphingomyelin and T. foetus glycophosphosphingolipids. The culture medium contained (greater than 10%) cholesterol, phosphatidylethanolamine, phosphatidylcholine, sphingomyelin and lysophosphatidylcholine. The fatty acyl groups of these major lipids of the trichomonads and the culture medium were similar. Those present in amounts greater than 5% of the total fatty acyl groups for a given lipid were myristic, palmitic, hexadecaenoic, stearic, oleic, linoleic, arachidonic and docosahexaenoic. When the trichomonads were exposed to radiolabeled lipids and lipid precursors, [14C]-labeled acetate and potential acetate precursors (glucose, threonine) were poorly incorporated and failed to label the fatty acyl groups of the trichomonad lipids. [14C]-labeled, C12-C22 saturated and unsaturated fatty acids were incorporated, unaltered, into phosphoglycerides and sphingolipids (sphingomyelin and glycophosphosphingolipids), but not into cholesteryl esters or triacylglycerols. Phosphoglycerides were preferentially labeled with unsaturated fatty acids and sphingolipids with saturated ones. This information inferred that the trichomonads: 1) were unable to biosynthesize fatty acids de novo, 2) took up unesterified fatty acids from the culture medium and used them in phosphoglyceride and sphingolipid biosynthesis and/or turnover, 4) did not use unesterified fatty acids in the biosynthesis or turnover of cholesteryl esters or triacylglycerols. Phosphatidylcholine and phosphatidylethanolamine, with [14C]labeled fatty acyl groups, and sphingomyelin, with 14C-labeled choline, were incorporated by the trichomonads. The phospholipids strongly labeled phosphoglycerides and sphingolipids, but not triacylglycerols, while the radioactivity of sphingomyelin [14C]choline remained associated solely with trichomonad sphingomyelin. Triacylglycerol, with 14C-labeled fatty acyl groups, was also incorporated, and labeled phosphoglycerides and sphingolipids. The results of those experiments suggested that trichomonads: (1) could take up culture medium phospholipids and triacylglycerols; (2) actively deacylated and reacylated phospholipids, but not triacylglycerols; (3) hydrolyzed exogenous triacylglycerols and used their fatty acyl groups for phospholipid acylations. Radiolabeled acetate, mevalonate and squalene were not incorporated into trichomonad cholesterol or cholesteryl esters. [14C]Cholesterol was incorporated unaltered, but was not esterified.(ABSTRACT TRUNCATED AT 400 WORDS)

Structures of glycophosphosphingolipids of Tritrichomonas foetus: a novel glycophosphosphingolipid.

The glycophosphosphingolipids of Tritrichomonas foetus, an aerotolerant parasite of the urogenital tract of cattle, have been characterized by a combination of metabolic labeling, chromatography, and tandem mass spectrometry. The acidic glycolipid fraction of T. foetus obtained by DEAE Sephadex A-25 column chromatography was subfractionated by high performance thin layer chromatography and the component lipids were purified by high performance liquid chromatography. Two nonsaponifiable lipid fractions, designated TF1 and TF2, could be metabolically labeled with [3H]myoinositol and [32P]orthophosphate. [3H]Fucose and [14C]ethanolamine were preferentially incorporated into the TF1 fraction. TF1 was partially hydrolyzed by alpha-fucosidase. Both TF1 and TF2 contain ceramides, the most abundant having either sphinganine or sphingosine and a 16:0 N-acyl group. TF2 contains inositolphosphoceramides. TF1, on the other hand, contains three closely related components, in each of which fucose is linked to inositol diphosphate with one of the phosphates linked to the ceramide moiety and the other phosphate either free or linked to ethanolamine or N-acetylethanolamine. TF1 appears to be a novel class of glycophosphosphingolipid which shows some structural similarities to the glycosylphosphatidylinositol anchors of eukaryotic membrane proteins.

Tegument galactosylceramides of the cestode Spirometra mansonoides.

The brush border-like surface of the tegument of the adult and the plerocercoid larva of a pseudophyllidean cestode, Spirometra mansonoides, has been shown to contain hydroxylated galactosylceramides. D-Galactosyl-N-(2-D-hydroxyoctadecanoyl)-D-phytosphingosine, D-galactosyl-N-(2-D-hydroxyoctadecanoyl)-D-dihydrosphingosine and D-galactosyl-N-(octadecanoyl)-D-phytosphingosine were identified as major glycosphingolipids in a tegumental plasma membrane fraction with associated microtriches, by combinations of chromatography (column, high performance thin-layer, gas-liquid), mass spectrometry (electron impact, field desorption, fast atom bombardment, collisionally induced decomposition) and proton nuclear magnetic resonance spectrometry. Galactosylceramides with hydroxylated long chain bases and fatty acids are known to occur in some eukaryotic microbes and in cells of vertebrate tissues exposed to plasma membrane destabilizing environments. This has led to a proposal that the capacity of hydroxylated ceramide moieties for intermolecular hydrogen bonding among themselves and with phosphoglycerides acts to stabilize the plasma membrane. Saturated fatty acyl groups in the ceramides would enhance stabilization by their orderly packing in the lipid bilayer. Consequently, the presence of such hydroxylated galactosylceramides in the tegument surface of S. mansonoides may contribute to the maintenance of its normal barrier properties in the face of the varied environmental insults encountered by the cestode in its life-cycle.