Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.1.53 (sialidase)
2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

IL-4 is important in controlling the development of immune responses. Following activation with anti-CD3epsilon under serum-free conditions, splenocytes from most normal (neu-1b) mouse strains directly produced IL-4 and other T cell cytokines. However, splenic T cells from SM/J and B10.SM (H-2v, neu-1a) strain mice, deficient in neu-1 sialidase activity, failed to produce IL-4 but produced normal levels of IL-2 following activation. Moreover, sialidase-deficient mice produced markedly less IgE and IgG1 Abs following immunization with protein Ags than did mouse strains with normal neu-1 sialidase activity. Enriched T cells from neu-1a mice failed to be effectively primed with exogenous murine IL-4 to become IL-4-producing cells. Treatment of splenocytes or enriched T cells from neu-1a mice with bacterial sialidase prior to activation or IL-4 priming promoted their subsequent capacity to produce IL-4. In contrast, activation of T cells from neu-1b mice in the presence of a sialidase inhibitor almost completely blocked subsequent IL-4 production. The presence of IL-4 during priming enhanced T cell expression of neu-1-specific sialidase activity and increased the membrane expression of asialo-G(M1) compared with T cells activated without IL-4. These results suggest that T cell-associated neu-1 sialidase is required for early IL-4 production by splenic T cells and is involved in the IL-4 priming process of conventional T cells to become active IL-4 producers.
...
PMID:The control of IL-4 gene expression in activated murine T lymphocytes: a novel role for neu-1 sialidase. 912 Feb 59

CD8+ T lymphocytes play a critical role in immunity to Trypanosoma cruzi. However, the target molecules of this T cell subset have not been elucidated. In this work, we report the identification of an H-2Kb-restricted CTL epitope within two trypomastigote surface Ags encoded by members of the T. cruzi sialidase/trans-sialidase gene superfamily. Octapeptide VDYNFTIV sensitized target cells for lysis by CD8+ CTL generated from spleens of T. cruzi-infected mice. Peptide-specific CD8+ T cell lines were cytotoxic, secreted IFN-gamma and TNF-alpha, but low to undetectable levels of IL-4 and IL-5, and were able, upon adoptive transfer, to confer a high degree of protection against challenge infection. Finally, the protective determinant appears to be conserved among parasites from diverse geographic locations. This constitutes the first identified class I MHC-restricted epitope in T. cruzi and provides the basis for the search of additional targets to be considered in the development of vaccines against Chagas' disease.
...
PMID:Identification of Trypanosoma cruzi trans-sialidase family members as targets of protective CD8+ TC1 responses. 955 Apr 13

A new T(H1)/T(H2) in vitro model for mechanistic studies and drug screening in human T cells was established working with ficoll-separated PBMCs or elutriated lymphocytes cultured in serum-free medium. Human T cells could be kept viable and reactive in this medium for several months. In this model, superantigens (SAs) were used to activate exclusively those T cell clones which were known to express specifically SA-binding Vbeta-chains of the T cell receptor. It was possible to identify the activated SA-specific T cells among the whole T cell population by using monoclonal antibodies against these Vbeta-chains and to follow responses involving receptor regulation and cytokine expression. The flow cytometric analysis revealed, that SA exposure caused an upregulation of the IL-2 receptor selectively in the SA-specific subpopulation. Only the T cells of this subpopulation could be shifted towards T(H1) or T(H2) differentiation, which was determined by the distribution of IFN-gamma and IL-4 positive cells. Regulation of IFN-gamma could be detected by flow cytometry after 18 h and that of IL-4 on the third day of cell culture. The differentiation status could be influenced by various measures: T(H1) shifts were achieved in the presence of IL-12 and anti-IL-4, whereas, T(H2) shifts were induced more slowly with monocyte-reduced elutriated lymphocytes in the presence of IL-4, IL-6, anti-IL-12, 1alpha,25-dihydroxy-vitamin-D3 or combinations thereof. It was found that sialidase stimulated whereas TGF-beta and pentoxifylline suppressed both kinds of T cell response. The T(H1)/T(H2) differentiation persisted for several weeks after primary activation if cells were expanded in IL-2 containing serum-free culture medium. Therefore, this human T(H1)/T(H2) in vitro model should be ideal for studying early and late events of infection, allergy, and autoimmunity as well as for investigating the cellular interactions involved. In addition, the early detection of the response pattern makes this model potentially useful for drug screening.
...
PMID:A new in vitro model for studying human T cell differentiation: T(H1)/T(H2) induction following activation by superantigens. 983 90

We have previously shown that costimulation of endothelial cells with IL-1 + IL-4 markedly inhibits VCAM-1-dependent adhesion under flow conditions. We hypothesized that sialic acids on the costimulated cell surfaces may contribute to the inhibition. Northern blot analyses showed that Gal beta 1-4GlcNAc alpha 2, 6-sialyltransferase (ST6N) mRNA was up-regulated in cultured HUVEC by IL-1 or IL-4 alone, but that the expression was enhanced by costimulation, whereas the level of Gal beta 1-4GlcNAc/Gal beta 1-3GalNAc alpha2,3-sialyltransferase (ST3ON) mRNA was unchanged. Removing both alpha 2,6- and alpha 2,3-linked sialic acids from IL-1 + IL-4-costimulated HUVEC by sialidase significantly increased VCAM-1-dependent adhesion, whereas removing alpha 2,3-linked sialic acid alone had no effect; adenovirus-mediated overexpression of ST6N with costimulation almost abolished the adhesion, which was reversible by sialidase. The same treatments of IL-1-stimulated HUVEC had no effect. Lectin blotting showed that VCAM-1 is decorated with alpha 2,6- but not alpha 2,3-linked sialic acids. However, overexpression of alpha 2,6-sialyltransferase did not increase alpha 2,6-linked sialic acid on VCAM-1 but did increase alpha 2,6-linked sialic acids on other proteins that remain to be identified. These results suggest that alpha 2,6-linked sialic acids on a molecule(s) inducible by costimulation with IL-1 + IL-4 but not IL-1 alone down-regulates VCAM-1-dependent adhesion under flow conditions.
...
PMID:Endothelial alpha 2,6-linked sialic acid inhibits VCAM-1-dependent adhesion under flow conditions. 1045 33

Infective forms of Trypanosoma cruzi, the parasite that causes Chagas' disease, express on their surface an enzyme denominated trans-sialidase (TS). The present study was designed to evaluate the naturally acquired immune responses to a bacterial recombinant protein representing the catalytic domain of TS in chronically infected chagasic individuals. The cellular immune response was measured by in-vitro T-cell proliferation and by interferon (INF)-gamma, interleukin (IL)-4 and IL-10 production in response to a whole-parasite homogenate and the recombinant protein. The peripheral blood mononuclear cells of 78.6% of 28 chagasic patients responded to the recombinant protein as estimated by T-cell proliferation. With respect to cytokine production, 88% of the cells of the chagasic individuals produced IFN-gamma on stimulation with the recombinant protein. In contrast, IL-4 or IL-10 were minimally produced in response to TS. The cellular immune response was specific because most healthy individuals never exposed to T. cruzi failed to react with this recombinant protein. The plasma of 71.4% or 100% of chagasic patients had IgG antibodies as determined by ELISA or by the presence of TS inhibitory antibodies, respectively. We conclude that the catalytic domain of TS is recognized by IFN-gamma producing type 1 cells and antibodies in a large proportion of patients infected with T. cruzi.
...
PMID:Chagasic patients develop a type 1 immune response to Trypanosoma cruzi trans-sialidase. 1060 90

Our previous studies have shown that the enzymatic activities of Neu-1, an endogenous sialidase encoded in the murine MHC, are involved in promoting IL-4 synthesis by naive CD4(+)T cells. Our present studies have characterized responsible sialoconjugate targets of Neu-1 and questioned possible biochemical mechanisms responsible for their regulatory influences on IL-4 gene expression. These studies determined that treatment of T cells with the naturally occurring ganglioside GM3 inhibited the production of IL-4 without affecting the production of IL-2. An analysis of IL-4-primed CD4(+)T cells further demonstrated that GM3 treatment specifically inhibited the restimulated production of IL-4, IL-5 and IL-13, without inhibiting the production of IL-2 and IFN-gamma. The inhibitory effects of GM3 could be overcome by treatment with thapsigargin or ionomycin, suggesting ganglioside regulation occurs upstream of activation-induced calcium mobilization. GM3 treatment attenuated the level of calcium influx following CD3epsilon crosslinking, and CD4(+)T cells from Neu-1-deficient B10.SM strain mice (neu-1(a)and IL-4-deficient) expressed reduced levels of intracellular calcium following activation. Our results indicate that activities by membrane gangliosides can influence the cytokine programs in CD4(+)T cells, possibly through the modulation of calcium responses induced by T cell activation.
...
PMID:Ganglioside control over IL-4 priming and cytokine production in activated T cells. 1088 Feb 42

Among the three isoenzymes of neuraminidase (Neu) or sialidase, Neu-1 has been suggested to be induced by cell activation and to be involved in IL (interleukin)-4 biosynthesis in murine T-cells. In the present study, we found that antigen-induced airway eosinophilia, a typical response dependent on Th2 (T-helper cell type 2) cytokines, as well as mRNA expression of Th2 cytokines, including IL-4, are suppressed in Neu-1-deficient mice, thereby demonstrating the in vivo role of murine Neu-1 in regulation of Th2 cytokines. To elucidate the roles of various sialidases in human T-cell activation, we investigated their tissue distribution, gene induction and function. Neu-1 is the predominant isoenzyme at the mRNA level in most tissues and cells in both mice and humans, including T-cells. T-cells also have significant levels of Neu-3 mRNAs, albeit much lower than those of Neu-1, whereas the levels of Neu-2 mRNAs are minimal. In human T-cells, both Neu-1 and Neu-3 mRNAs are significantly induced by T-cell-receptor stimulation, as is sialidase activity against 4-methylumbelliferyl- N -acetylneuramic acid (a substrate for both Neu-1 and Neu-3) and the ganglioside G(D1a) [NeuAcalpha2-3Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-4Glcbeta1-cer] (a substrate for Neu-3, but not for Neu-1). The expression of the two sialidase genes may be under differential regulation. Western blot analysis and enzymic comparison with recombinant sialidases have revealed that Neu-3 is induced as a major isoform in activated cells. The induction of Neu-1 and Neu-3 in T-cells is unique. In human monocytes and neutrophils stimulated with various agents, the only observation of sialidase induction has been by IL-1 in neutrophils. Functionally, a major difference has been observed in Jurkat T-cell lines over-expressing Neu-1- and Neu-3. Upon T-cell receptor stimulation, IL-2, interferon-gamma, IL-4 and IL-13 are induced in the Neu-1 line, whereas in the Neu-3 line the same cytokines are induced, with the exception of IL-4. Taken together, these results suggest an important immunoregulatory role for both Neu-1 and Neu-3 in humans.
...
PMID:Induction of lysosomal and plasma membrane-bound sialidases in human T-cells via T-cell receptor. 1499 89

Recombinant protein glycosylation profiles have been shown to affect the in-vivo half-life, and therefore the efficacy and economics, for many therapeutics. While much research has been conducted correlating the effects of various stimuli on recombinant protein glycosylation characteristics, relatively little work has examined glycosylation-related gene-expression profiles. In this study, the effects of galactose feeding on the gene-expression profiles for five key glycosylation-related genes were determined for Chinese hamster ovary cells producing a recombinant IL-4/13 cytokine trap fusion. The genes investigated were sialidase, a putative alpha2,3-sialyltransferase, CMP-sialic acid transporter, beta1,4-galactosyltransferase, and UDP-galactosyltransferase. Additionally, the sialic acid content (sialylation) of the recombinant protein was examined. The peak sialic acid content of the IL-4/13 cytokine trap fusion protein was observed to be similar for the control and galactose-fed cultures. The gene-expression profiles for four of the glycosylation genes were observed to be sensitive to the glucose concentration and not significantly different for the control and galactose-fed cultures prior to glucose depletion. However, the sialidase gene-expression profiles were different for the control and galactose-fed cultures. The sialidase gene-expression profile increased significantly for the galactose-fed cultures prior to glucose depletion, whereas for the control cultures, the sialidase gene-expression profiles did not increase until the late stationary phase. The intracellular sialidase enzyme activity decreased exponentially with time for the control cultures; however, for the galactose-fed cultures, the intracellular sialidase enzyme activity decreased initially and then remained relatively high compared to the control cultures. These results indicate that the galactose feeding may increase the potential for desialylation, which offsets any improvements in the sialylation rate due to increased substrate levels. Thus, galactose feeding is an unnecessary expense for the production of the IL-4/13 cytokine trap fusion protein in a batch process.
...
PMID:Gene-expression profiles for five key glycosylation genes for galactose-fed CHO cells expressing recombinant IL-4/13 cytokine trap. 1581 60

Cloning of the T-cell receptor genes is a critical step when generating T-cell receptor transgenic mice. Because T-cell receptor molecules are clonotypical, isolation of their genes requires reverse transcriptase-assisted PCR using primers specific for each different Valpha or Vbeta genes or by the screening of cDNA libraries generated from RNA obtained from each individual T-cell clone. Although feasible, these approaches are laborious and costly. The aim of the present study was to test the application of the non-palindromic adaptor-PCR method as an alternative to isolate the genes encoding the T-cell receptor of an antigen-specific T-cell hybridoma. For this purpose, we established hybridomas specific for trans-sialidase, an immunodominant Trypanosoma cruzi antigen. These T-cell hybridomas were characterized with regard to their ability to secrete interferon-gamma, IL-4, and IL-10 after stimulation with the antigen. A CD3+, CD4+, CD8- interferon-gamma-producing hybridoma was selected for the identification of the variable regions of the T-cell receptor by the non-palindromic adaptor-PCR method. Using this methodology, we were able to rapidly and efficiently determine the variable regions of both T-cell receptor chains. The results obtained by the non-palindromic adaptor-PCR method were confirmed by the isolation and sequencing of the complete cDNA genes and by the recognition with a specific antibody against the T-cell receptor variable beta chain. We conclude that the non-palindromic adaptor-PCR method can be a valuable tool for the identification of the T-cell receptor transcripts of T-cell hybridomas and may facilitate the generation of T-cell receptor transgenic mice.
...
PMID:The non-palindromic adaptor-PCR method for the identification of the T-cell receptor genes of an interferon-gamma-secreting T-cell hybridomaspecific for trans-sialidase, an immunodominant Trypanosoma cruzi antigen. 1650 14

Trypanosoma cruzi trypomastigotes continuously shed into the medium plasma membrane fragments sealed as vesicles enriched in glycoproteins of the gp85 and trans-sialidase (TS) superfamily and alpha-galactosyl-containing glycoconjugates. Injection of a vesicle fraction into BALB/c mice prior to T. cruzi infection led to 40% of deaths on the 16thday post-infection and 100% on day 20th whereas 20% of untreated animals survived for more than 30days. The vesicle-treated animals developed severe heart pathology, with intense inflammatory reaction and higher number of amastigote nests. Analysis of the inflammatory infiltrates 15days after infection showed predominance of TCD4(+) lymphocytes and macrophages, but not of TCD8(+) cells, as well as a decrease of areas labeled with anti-iNOS antibodies as compared to the control. Higher levels of IL-4 and IL-10 mRNAs were found in the hearts and higher IL-10 and lower NO levels in splenocytes of vesicles pretreated animals. Treatment of mice with neutralizing anti-IL-10 or anti-IL-4 antibodies precluded the effects of pre-inoculation of membrane vesicles on infection. These results indicate that T. cruzi shed membrane components increase tissue parasitism and inflammation by stimulation of IL-4 and IL-10 synthesis and thus may play a central role in the pathogenesis of Chagas' disease acute phase.
...
PMID:Trypanosoma cruzi: parasite shed vesicles increase heart parasitism and generate an intense inflammatory response. 1902 94


1

---