| 1. |
- Andersson, Ida E, 1982-, et al.
(författare)
-
Design of glycopeptides used to investigate class II MHC binding and T-Cell responses associated with autoimmune arthritis
- 2011
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 6:3, s. e17881-
-
Tidskriftsartikel (refereegranskat)abstract
- The glycopeptide fragment CII259–273 from type II collagen (CII) binds to the murine Aq and human DR4 class II Major Histocompatibility Complex (MHC II) proteins, which are associated with development of murine collagen-induced arthritis (CIA) and rheumatoid arthritis (RA), respectively. It has been shown that CII259–273 can be used in therapeutic vaccination of CIA. This glycopeptide also elicits responses from T-cells obtained from RA patients, which indicates that it has an important role in RA as well. We now present a methodology for studies of (glyco)peptide-receptor interactions based on a combination of structure-based virtual screening, ligand-based statistical molecular design and biological evaluations. This methodology included the design of a CII259–273 glycopeptide library in which two anchor positions crucial for binding in pockets of Aq and DR4 were varied. Synthesis and biological evaluation of the designed glycopeptides provided novel structure-activity relationship (SAR) understanding of binding to Aq and DR4. Glycopeptides that retained high affinities for these MHC II proteins and induced strong responses in panels of T-cell hybridomas were also identified. An analysis of all the responses revealed groups of glycopeptides with different response patterns that are of high interest for vaccination studies in CIA. Moreover, the SAR understanding obtained in this study provides a platform for the design of second-generation glycopeptides with tuned MHC affinities and T-cell responses.
|
|
| 2. |
- Andersson, Ida E., 1982-, et al.
(författare)
-
(E)-Alkene and Ethylene Isosteres Substantially Alter the Hydrogen-Bonding Network in Class II MHC Aq/Glycopeptide Complexes and Affect T-Cell Recognition
- 2011
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 133:36, s. 14368-14378
-
Tidskriftsartikel (refereegranskat)abstract
- The structural basis for antigen presentation by class II major histocompatibility complex (MHC) proteins to CD4(+) T-cells is important for understanding and possibly treating autoimmune diseases. In the work described in this paper, (E)-alkene and ethylene amide-bond isosteres were used to investigate the effect of removing hydrogen-bonding possibilities from the CII259-270 glycopeptide, which is bound by the arthritis-associated murine A(q) class II MHC protein. The isostere-modified glycopeptides showed varying and unexpectedly large losses of A(q) binding that could be linked to the dynamics of the system. Molecular dynamics (MD) simulations revealed that the backbone of CII259-270 and the A(q) protein are able to form up to 11 hydrogen bonds, but fewer than this number are present at any one time. Most of the strong hydrogen-bond interactions were formed by the N-terminal part of the glycopeptide, i.e., in the region where the isosteric replacements were made. The structural dynamics also revealed that hydrogen bonds were strongly coupled to each other; the loss of one hydrogen-bond interaction had a profound effect on the entire hydrogen-bonding network. The A(q) binding data revealed that an ethylene isostere glycopeptide unexpectedly bound more strongly to A(q) than the corresponding (E)-alkene, which is in contrast to the trend observed for the other isosteres. Analysis of the MD trajectories revealed that the complex conformation of this ethylene isostere was structurally different and had an altered molecular interaction pattern compared to the other A(q)/glycopeptide complexes. The introduced amide-bond isosteres also affected the interactions of the glycopeptide/A(q) complexes with T-cell receptors. The dynamic variation of the patterns and strengths of the hydrogen-bond interactions in the class II MHC system is of critical importance for the class II MHC/peptide/TCR signaling system.
|
|
| 3. |
- Andersson, Ida E., 1982-, et al.
(författare)
-
Oxazole-modified glycopeptides that target arthritis-associated class II MHC Aq and DR4 proteins
- 2010
-
Ingår i: Organic and biomolecular chemistry. - : RSC Publishing. - 1477-0520 .- 1477-0539. ; 8:13, s. 2931-2940
-
Tidskriftsartikel (refereegranskat)abstract
- The glycopeptide CII259-273, a fragment from type II collagen (CII), can induce tolerance in mice susceptible to collagen-induced arthritis (CIA), which is a validated disease model for rheumatoid arthritis (RA). Here, we describe the design and synthesis of a small series of modified CII259-273 glycopeptides with oxazole heterocycles replacing three potentially labile peptide bonds. These glycopeptidomimetics were evaluated for binding to murine CIA-associated A(q) and human RA-associated DR4 class II major histocompatibility complex (MHC) proteins. The oxazole modifications drastically reduced or completely abolished binding to A(q). Two of the glycopeptidomimetics were, however, well tolerated in binding to DR4 and they also induced strong responses by one or two DR4-restricted T-cell hybridomas. This work contributes to the development of an altered glycopeptide for inducing immunological tolerance in CIA, with the long-term goal of developing a therapeutic vaccine for treatment of RA.
|
|
| 4. |
- Andersson, Ida E., 1982-, et al.
(författare)
-
Probing Molecular Interactions within Class II MHC A(q)/Glycopeptide/T-Cell Receptor Complexes Associated with Collagen-Induced Arthritis.
- 2007
-
Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 1520-4804 .- 0022-2623. ; 50:23, s. 5627-5643
-
Tidskriftsartikel (refereegranskat)abstract
- T cells obtained in a mouse model for rheumatoid arthritis are activated by a glycopeptide fragment from rat type II collagen (CII) bound to the class II major histocompatibility complex A(q) molecule. We report a comparative model of A(q) in complex with the glycopeptide CII260-267. This model was used in a structure-based design approach where the amide bond between Ala(261) and Gly(262) in the glycopeptide was selected for replacement with psi[COCH2], psi[CH2NH2+], and psi[(E)-CH=CH] isosteres. Ala-Gly isostere building blocks were then synthesized and introduced in CII260-267 and CII259-273 glycopeptides. The modified glycopeptides were evaluated for binding to the A(q) molecule, and the results were interpreted in view of the A(q)/glycopeptide model. Moreover, recognition by a panel of T-cell hybridomas revealed high sensitivity for the backbone modifications. These studies contribute to the understanding of the interactions in the ternary A(q)/glycopeptide/T-cell receptor complexes that activate T cells in autoimmune arthritis and suggest possibilities for new vaccination approaches.
|
|
| 5. |
- Dzhambazov, Balik, et al.
(författare)
-
In vitro screening for antitumour activity of Clinopodium vulgare L. (Lamiaceae) extracts.
- 2002
-
Ingår i: Biological and Pharmaceutical Bulletin. - : Pharmaceutical Society of Japan. - 0918-6158 .- 1347-5215. ; 25:4, s. 499-504
-
Tidskriftsartikel (refereegranskat)abstract
- Aqueous extract of Clinopodium vulgare L. showed strong antitumour activity when tested in vitro on A2058 (human metastatic melanoma), HEp-2 (epidermoid carcinoma, larynx, human) and L5178Y (mouse lymphoma) cell lines-6 h after treatment disintegration of the nuclei and cell lysis started. Applied at a concentration of 80 microg/ml it reduced the cell survival to 1.0, 5.6 and 6.6%, respectively. The concentrations of aqueous extract inhibiting the growth of A2058, HEp-2 and L5178Y cells by 50% (IC50 values) were calculated to be 20, 10 and 17.8 microg/ml respectively. Two groups of active substances were detected: the first one, probably combining glycosides, influenced adhesion, while the second one caused massive cell vacuolisation. The chloroform extract, which contained ursolic acid and gentriacontan had also cytotoxic, however a little bit weaker effect. All changes observed were irreversible.
|
|
| 6. |
- Dzhambazov, Balik, et al.
(författare)
-
Karyotypic analysis of two algae species Scenedesmus incrassatulus Bohl and Scenedesmus antennatus Bréb (Chlorophyta, Chlorococcales).
- 2003
-
Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 1601-5223 .- 0018-0661. ; 139:1, s. 35-40
-
Tidskriftsartikel (refereegranskat)abstract
- The karyotypes (number, morphology and size of the chromosomes) of two algae species of Scenedesmus genus, S. incrassatulus and S. antennatus, were studied. The karyotype of S. incrassatulus (n=4) was asymmetric, characterized by two large metacentric, one large submetacentric and one small metacentric chromosomes. The karyotype assembly of S. antennatus (n=6) reveals two metacentrics and four submetacentrics. This karyotype was symmetric. The general chromosomal formulae of both species, as well as the total average metaphase length of their haploid set are presented. The results of chromosomal studies of other related species are compared and discussed. Data from the karyotypic analysis showed that S. incrassatulus, S. antennatus and S. obliquus are separate biological species from taxonomical point of view.
|
|
| 7. |
- Dzhambazov, Balik, et al.
(författare)
-
Karyotypic differences and evolutionary tendencies of some species from the subgenus Obliquodesmus Mlad. of genus Scenedesmus Meyen (Chlorophyta, Chlorococcales)
- 2006
-
Ingår i: Journal of Genetics. - 0022-1333. ; 85:1, s. 39-44
-
Tidskriftsartikel (refereegranskat)abstract
- Karyotype structures of Scenedesmus acuminatus (Lagerch.) Chod. and Scenedesmus pectinatus Meyen are compared. The karyotype of S. acuminatus (n = 5) is described for the first time. It reveals four large metacentric and one large submeta centric chromosomes (4M + 1SM). The established karyotype differences have been helpful in clarifying the taxonomic position of these two species. The cytological analyses of other related clonal cultures suggest an evolutionary transition from S. pectinatus towards S. regularis through S. pectinatus f. regularis, which correlates with the morphological data about their variability. These results are discussed from the cytogenetic, morphological and evolutionary point of view. On the basis of the karyotypic analysis, it was confirmed that from a taxonomic point of view S. pectinalus, S. acuminatus and S. regularis are separate biological species.
|
|
| 8. |
- Dzhambazov, Balik, et al.
(författare)
-
Morphological, genetic and functional variability of a T-cell hybridoma line.
- 2003
-
Ingår i: Folia Biologica. - 0015-5500. ; 49:2, s. 87-94
-
Tidskriftsartikel (refereegranskat)abstract
- The variability in the morphology, modal number of chromosomes, TCR expression and functional reactivity of a CII-specific T-cell hybridoma at continuous subcultivation have been investigated. As the number of passages increased, besides the oval semiadherent cells (normal phenotype), fibroblast-like cells (transformed phenotype) were also observed. The two cell subpopulations differed in their karyotype characteristic, as well as in their functional reactivity. The cell population with a normal phenotype was characterized by a tetramodal number of chromosomes (30, 40, 48 and 70) and trisomies of chromosomes 6 and 14, while the cell population with a transformed phenotype was characterized by a trimodal number of chromosomes (11, 68 and 74) and trisomy of chromosome 12. A nullisomy of sex chromosomes was established in both types of cells. In the initial passages of subcultivation, 73.04% of the cells with a normal morphological phenotype expressed TCR-CD3 complexes on their surface and possessed high functional reactivity. After a two-week subcultivation, the values of these indices went down considerably: 46.11% of the cells expressed functional TCR-CD3 complexes, as a result of which their functional reactivity decreased. Only 2.71% of the cells with a transformed morphological phenotype expressed functional TCR-CD3 complexes on their surface. In these cells, a total loss of reactivity towards the specific antigens was established. The achieved results show that at continuous subcultivation the T-cell hybridomas are unstable, and with the increase in the number of passages there appear chromosome rearrangements, leading to loss of their functional reactivity.
|
|
| 9. |
- Dzhambazov, Balik, et al.
(författare)
-
The major T cell epitope on type II collagen is glycosylated in normal cartilage but modified by arthritis in both rats and humans
- 2005
-
Ingår i: European Journal of Immunology. - : Wiley. - 1521-4141 .- 0014-2980. ; 35:2, s. 357-366
-
Tidskriftsartikel (refereegranskat)abstract
- Type II collagen (CII) is a target for autoreactive T cells in both rheumatoid arthritis and the murine model collagen-induced arthritis. The determinant core of CII has been identified as CII260-270, and the alteration of this T cell epitope by posttranslational modifications is known to be critical for development of arthritis in mice. Using CII-specific T cell hybridomas we have now shown that the immunodominant T cell epitope in the normal (healthy) human and rat joint cartilage is O-glycosylated at the critical T cell receptor recognition position 264 with a mono- or di-saccharide attached to a hydroxylysine. In contrast, in the arthritic human and rat joint cartilage there are both glycosylated and non-glycosylated CII forms. Glycosylated CII from normal cartilage could not be recognized by T cells reactive to peptides having only lysine or hydroxylysine at position 264, showing that antigen-presenting cells could not degrade the O-linked carbohydrate. Thus, the variable forms of the glycosylated epitope are determined by the structures present in cartilage, and these vary during the disease course. We conclude that the chondrocyte determines the structures presented to the immune system and that these structures are different in normal versus arthritic states.
|
|
| 10. |
- Dzhambazov, Balik, et al.
(författare)
-
The major T cell epitope on type II collagen is glycosylated in normal cartilage but modified by arthritis in both rats and humans
- 2005
-
Ingår i: EUROPEAN JOURNAL OF IMMUNOLOGY. - : Wiley. - 0014-2980 .- 1521-4141. ; 35:2, s. 357-66
-
Tidskriftsartikel (refereegranskat)abstract
- Type II collagen (CII) is a target for autoreactive T cells in both rheumatoid arthritis and the murine model collagen-induced arthritis. The determinant core of CII has been identified as CII260-270, and the alteration of this T cell epitope by posttranslational modifications is known to be critical for development of arthritis in mice. Using CII-specific T cell hybridomas we have now shown that the immunodominant T cell epitope in the normal (healthy) human and rat joint cartilage is O-glycosylated at the critical T cell receptor recognition position 264 with a mono- or di-saccharide attached to a hydroxylysine. In contrast, in the arthritic human and rat joint cartilage there are both glycosylated and non-glycosylated CII forms. Glycosylated CII from normal cartilage could not be recognized by T cells reactive to peptides having only lysine or hydroxylysine at position 264, showing that antigen-presenting cells could not degrade the O-linked carbohydrate. Thus, the variable forms of the glycosylated epitope are determined by the structures present in cartilage, and these vary during the disease course. We conclude that the chondrocyte determines the structures presented to the immune system and that these structures are different in normal versus arthritic states.
|
|
