| 1. |
- Sayitoglu, Ece Canan, et al.
(författare)
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Boosting Natural Killer Cell-Mediated Targeting of Sarcoma Through DNAM-1 and NKG2D
- 2020
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Ingår i: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Sarcomas are malignancies of mesenchymal origin that occur in bone and soft tissues. Many are chemo- and radiotherapy resistant, thus conventional treatments fail to increase overall survival. Natural Killer (NK) cells exert anti-tumor activity upon detection of a complex array of tumor ligands, but this has not been thoroughly explored in the context of sarcoma immunotherapy. In this study, we investigated the NK cell receptor/ligand immune profile of primary human sarcoma explants. Analysis of tumors from 32 sarcoma patients identified the proliferative marker PCNA and DNAM-1 ligands CD112 and/or CD155 as commonly expressed antigens that could be efficiently targeted by genetically modified (GM) NK cells. Despite the strong expression of CD112 and CD155 on sarcoma cells, characterization of freshly dissociated sarcomas revealed a general decrease in tumor-infiltrating NK cells compared to the periphery, suggesting a defect in the endogenous NK cell response. We also applied a functional screening approach to identify relevant NK cell receptor/ligand interactions that induce efficient anti-tumor responses using a panel NK-92 cell lines GM to over-express 12 different activating receptors. Using GM NK-92 cells against primary sarcoma explants (n = 12) revealed that DNAM-1 over-expression on NK-92 cells led to efficient degranulation against all tested explants (n = 12). Additionally, NKG2D over-expression showed enhanced responses against 10 out of 12 explants. These results show that DNAM-1(+) or NKG2D(+) GM NK-92 cells may be an efficient approach in targeting sarcomas. The degranulation capacity of GM NK-92 cell lines was also tested against various established tumor cell lines, including neuroblastoma, Schwannoma, melanoma, myeloma, leukemia, prostate, pancreatic, colon, and lung cancer. Enhanced degranulation of DNAM-1(+) or NKG2D(+) GM NK-92 cells was observed against the majority of tumor cell lines tested. In conclusion, DNAM-1 or NKG2D over-expression elicited a dynamic increase in NK cell degranulation against all sarcoma explants and cancer cell lines tested, including those that failed to induce a notable response in WT NK-92 cells. These results support the broad therapeutic potential of DNAM-1(+) or NKG2D(+) GM NK-92 cells and GM human NK cells for the treatment of sarcomas and other malignancies.
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| 2. |
- Brodin, Petter, et al.
(författare)
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Natural Killer Cell Tolerance Persists Despite Significant Reduction of Self MHC Class I on Normal Target Cells in Mice
- 2010
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:10, s. e13174-
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Tidskriftsartikel (refereegranskat)abstract
- Background: A major group of murine inhibitory receptors on Natural Killer (NK) cells belong to the Ly49 receptor family and recognize MHC class I molecules. Infected or transformed target cells frequently downmodulate MHC class I molecules and can thus avoid CD8(+) T cell attack, but may at the same time develop NK cell sensitivity, due to failure to express inhibitory ligands for Ly49 receptors. The extent of MHC class I downregulation needed on normal cells to trigger NK cell effector functions is not known. Methodology/Principal Findings: In this study, we show that cells expressing MHC class I to levels well below half of the host level are tolerated in an in vivo assay in mice. Hemizygous expression (expression from only one allele) of MHC class I was sufficient to induce Ly49 receptor downmodulation on NK cells to a similar degree as homozygous expression, despite a strongly reduced cell surface level of MHC class I. Co-expression of weaker MHC class I ligands in the host did not have any further effect on the degree of Ly49 downmodulation. Furthermore, a single MHC class I allele could downmodulate up to three Ly49 receptors on individual NK cells. Only when NK cells simultaneously expressed several Ly49 receptors and hemizygous MHC class I levels, a putative threshold for Ly49 downmodulation was reached. Conclusion: Collectively, our findings suggest that in interactions between NK cells and normal untransformed cells, MHC class I molecules are in most cases expressed in excess compared to what is functionally needed to ensure self tolerance and to induce maximal Ly49 downmodulation. We speculate that the reason for this is to maintain a safety margin for otherwise normal, autologous cells over a range of MHC class I expression levels, in order to ensure robustness in NK cell tolerance.
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| 3. |
- Duru, Adil Doganay
(författare)
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MHC-class I restricted peptide-based immunomodulation of CD8+ T and NK cells
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main aims of the immune system are to protect the host from potential threats by distinguishing self from non-self and altered-self. T cells and NK cells play a key role in the identification and elimination of threats by scanning a repertoire of peptide epitopes presented by major histocompatibility complex (MHC) molecules. Thus, MHC molecules play a pivotal role in the initiation and/or modulation of both T and NK cell effector functions, acting as ‘windows’ of the cells presenting their inner condition. This thesis focuses on the molecular interactions between T cell receptors (TCRs), NK cell receptors (NKR) and MHC class I molecules (MHC-I). The presented results demonstrate that it is possible to efficiently manipulate T and NK cell responses through MHC-restricted epitopes and altered peptide ligands (APL). Primarily, our investigations of the potential impact of post-translationally modified (PTM) peptides on immunosurveillance revealed the first structural and biochemical evidence for how nitrotyrosinated neoantigens may enable viral escape from immune recognition, as well as break immune tolerance by either impairing MHC/peptide complex (pMHC) stability and/or altering interactions with the TCR surface. Moreover, structural alterations can change the biochemistry of TCR-pMHC interactions, which may affect the immunogenicity of altered peptide ligands (APLs). We demonstrated that a TCR specific for an immunodominant epitope makes use of a different thermodynamic strategy to cross-react with a weak agonist APL in order to adapt to structural modifications in the pMHC. Thus, understanding the molecular constraints of TCR interactions with MHC-restricted epitopes and APLs is essential to develop novel approaches to modulate T cell responses and to achieve “T cell cross-reactivity”, which is the main objective of designing APLs targeting viral- and tumor associated antigens. Additionally, we have demonstrated that it is possible to modulate T cell responses through the use of an unconventional peptide modification strategy that systematically targets evolutionarily conserved residues of the MHC in order to improve pMHC stability and thus immunogenicity. Importantly, introduced modifications efficiently improved the immunogenicity of a viral escape epitope and immunization with the modified epitope generated distinct and focused cross-reactive T cell populations against the original peptide. Thus, targeting evolutionarily conserved residues of MHC provides a novel approach to optimize MHC-I restricted epitopes for future anti-viral or -tumor vaccines. Finally, our findings suggest that, in interactions between NK cells and normal cells, MHC-I is in most cases expressed in excess ensuring self-tolerance and preventing autoimmunity. More interestingly, we demonstrated that NK cell activation can be modulated through the use of MHC-I restricted peptides. This may have future implications in attempts to sensitize the immune system against previously inert targets, which stands out as an important outcome in the frame of this thesis.
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| 4. |
- Duru, Adil Doganay, et al.
(författare)
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Tuning antiviral CD8 T-cell response via proline-altered peptide ligand vaccination
- 2020
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Ingår i: PLoS Pathogens. - : PUBLIC LIBRARY SCIENCE. - 1553-7366 .- 1553-7374. ; 16:5
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Tidskriftsartikel (refereegranskat)abstract
- Viral escape from CD8(+) cytotoxic T lymphocyte responses correlates with disease progression and represents a significant challenge for vaccination. Here, we demonstrate that CD8(+) T cell recognition of the naturally occurring MHC-I-restricted LCMV-associated immune escape variant Y4F is restored following vaccination with a proline-altered peptide ligand (APL). The APL increases MHC/peptide (pMHC) complex stability, rigidifies the peptide and facilitates T cell receptor (TCR) recognition through reduced entropy costs. Structural analyses of pMHC complexes before and after TCR binding, combined with biophysical analyses, revealed that although the TCR binds similarly to all complexes, the p3P modification alters the conformations of a very limited amount of specific MHC and peptide residues, facilitating efficient TCR recognition. This approach can be easily introduced in peptides restricted to other MHC alleles, and can be combined with currently available and future vaccination protocols in order to prevent viral immune escape. Author summary Viral escape mutagenesis correlates often with disease progression and represents a major hurdle for vaccination-based therapies. Here, we have designed and developed a novel generation of altered epitopes that re-establish and enhance significantly CD8(+) T cell recognition of a naturally occurring viral immune escape variant. Biophysical and structural analyses provide a clear understanding of the molecular mechanisms underlying this reestablished recognition. We believe that this approach can be implemented to currently available or novel vaccination approaches to efficiently restore T cell recognition of virus escape variants to control disease progression.
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| 5. |
- Hafstrand, Ida, et al.
(författare)
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Successive crystal structure snapshots suggest the basis for MHC class I peptide loading and editing by tapasin
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 116:11, s. 5055-5060
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Tidskriftsartikel (refereegranskat)abstract
- MHC-I epitope presentation to CD8(+) T cells is directly dependent on peptide loading and selection during antigen processing. However, the exact molecular bases underlying peptide selection and binding by MHC-I remain largely unknown. Within the peptide-loading complex, the peptide editor tapasin is key to the selection of MHC-I-bound peptides. Here, we have determined an ensemble of crystal structures of MHC-I in complex with the peptide exchange-associated dipeptide GL, as well as the tapasin-associated scoop loop, alone or in combination with candidate epitopes. These results combined with mutation analyses allow us to propose a molecular model underlying MHC-I peptide selection by tapasin. The N termini of bound peptides most probably bind first in the N-terminal and middle region of the MHC-I peptide binding cleft, upon which the peptide C termini are tested for their capacity to dislodge the tapasin scoop loop from the F pocket of the MHC-I cleft. Our results also indicate important differences in peptide selection between different MHC-I alleles.
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| 6. |
- Lund, Johan, et al.
(författare)
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Lenalidomide versus lenalidomide plus dexamethasone prolonged treatment after second-line lenalidomide plus dexamethasone induction in multiple myeloma
- 2018
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Ingår i: Cancer Medicine. - : WILEY. - 2045-7634. ; 7:6, s. 2256-2268
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Tidskriftsartikel (refereegranskat)abstract
- Lenalidomide (Len) plus dexamethasone (Dex) is approved for the treatment of relapsed or refractory multiple myeloma (RRMM). It is possible that single-agent Len may be effective as prolonged treatment regimen in RRMM once patients demonstrate an initial response to Len+Dex induction. Patients with RRMM who responded to first-line Len+Dex in an observational study (NCT01430546) received up to 24 cycles of either Len (25mg/day) or Len+Dex (25mg/day and 40mg/week) as prolonged treatment in a subsequent phase 2 clinical trial (NCT01450215). In the observational study (N = 133), median time to response was 1.7 (range 0.6-9.6) months. A complete response to all treatments received in both studies was observed in 11% of patients; very good partial response and partial response rates were 31% and 38%, respectively. Corresponding response rates in the subgroup of patients who did not enter the phase 2 trial (n = 71) were 3%, 18%, and 39%, respectively. Rates of disease progression at 2years in the phase 2 trial were 47% versus 31% for Len versus Len+Dex (P = 0.14). After 36months median follow-up in surviving patients, median time to progression was not reached with Len+Dex and was 24.9months (95% confidence interval 12.5-not calculable, P amp;lt; 0.001) with Len. Three-year OS among the total observational study population was 61% (95% CI, 52-69%). The corresponding rate among patients who entered the phase 2 clinical trial was 73% (95% CI, 60-83%) and was significantly lower among those patients who achieved PR but did not proceed into the phase 2 trial (55%; P = 0.01). In the phase 2 trial, OS was 73% in both treatment arms (P = 0.70). Neutropenia and thrombocytopenia were more common with prolonged (phase 2 trial) versus short-term (observational study) Len administration but remained manageable. Prolonged treatment with Len with or without Dex provides sustained, clinically relevant responses and demonstrates an acceptable safety profile.
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