43 research outputs found
Molecular requirements for T cell recognition by a major histocompatibility complex class II-restricted T cell receptor: The involvement of the fourth hypervariable loop of the Vα domain
No full textThe role of two central residues (K68, E69) of the fourth hypervariable loop of the Vα domain (HV4α) in antigen recognition by an MHC class II- restricted T cell receptor (TCR) has been analyzed. The TCR recognizes the NH2-terminal peptide of myelin basic protein (Ac1-11, acetylated at NH2 terminus) associated with the class II MHC molecule I-A(u). Lysine 68 (K68) and glutamic acid 69 (E69) of HV4α have been mutated both individually and simultaneously to alanine (K68A, E69A). The responsiveness of transfectants bearing wild-type and mutated TCRs to Ac1-11-I-A(u) complexes has been analyzed in the presence and absence of expression of the coreceptor CD4. The data demonstrate that in the absence of CD4 expression, K68 plays a central role in antigen responsiveness. In contrast, the effect of mutating E69 to alanine is less marked. CD4 coexpression can partially compensate for the loss of activity of the K68A mutant transfectants, resulting in responses that, relative to those of the wild-type transfectants, are highly sensitive to anti-CD4 antibody blockade. The observations support models oft cell activation in which both the affinity of the TCR for cognate ligand and the involvement of coreceptors determine the outcome of the T cell-antigen- presenting cell interaction.</p
Characterization of the interaction of a TCR α chain variable domain with MHC II I-A molecules
No full textThe αβ TCR recognizes peptides bound to MHC molecules. In the present study, we analyzed the interaction of a soluble TCR α chain variable domain (V(α)4.2-J(α)40; abbreviated to V(α)4.2) with the MHC class II molecule I-A(u). V(α)4.2 bound specifically to I-A(u) expressed on the surface of a transfected thymoma cell line. Modifications in the amino acid residues located within the three complementarity-determining regions (CDRs) of the V(α) domain did not markedly affect this interaction. However, mutation of glutamic acid to alanine at position 69 of the fourth hypervariable region (HV4α) significantly increased the binding. Antibody inhibition studies suggested that the binding site was partly contributed by a region of the β chain of I-A(u). Furthermore, the binding of V(α)4.2 to the MHC molecule was dependent on the nature of the peptide bound in the groove. Soluble V(α)4.2 specifically inhibited the activation of TCR transfectants by I-A(u)-expressing cells pulsed with an N-terminal peptide of myelin basic protein. V(α)4.2 also bound to MHC class II-expressing spleen cell populations from mice of the H-2(u) and H-2(d) haplotypes. The binding of V(α)4.2 to I-A molecules might explain the immunoregulatory effects reported previously for TCR α chains. This V(α)4.2 interaction may also be relevant to models of antigen presentation involving the binding of intact proteins to MHC class II molecules followed by their processing to generate epitopes suitable for T cell recognition.</p
Induction of a type 1 regulatory CD4 T cell response following V<sub>β</sub>8.2 DNA vaccination results in immune deviation and protection from experimental autoimmune encephalomyelitis
No full textDNA vaccination has been used to generate effective cellular as well as humoral immunity against target antigens. Here we have investigated the induction and involvement of regulatory T cell (Treg) responses in mediating prevention of experimental autoimmune encephalomyelitis (EAE), following vaccination with plasmid DNA encoding the TCR Vβ8.2 chain predominantly displayed on disease-causing lymphocytes. Vaccination with DNA encoding the wild-type TCR results in priming of type 1 CD4 Treg and skewing of the global response to myelin basic protein in a Th2 direction, leading to significant protection from disease. In contrast, vaccination with mutant DNA encoding altered residues critically involved in recognition by the Treg results in priming of a type 2 regulatory response which fails to mediate immune deviation or protection from EAE. Control mice immunized with DNA, encoding TCR with changes at an irrelevant site, were protected from antigen-induced disease. Furthermore, protection can be transferred into naive recipients with CD4 Treg from wild-type DNA-immunized mice but not from animals vaccinated with the mutant DNA. These data suggest that vaccination with plasmid DNA encoding one or multiple Vβ genes can be exploited to enhance natural regulatory responses for intervention in autoimmune conditions.</p
On a reconstruction problem
No full textAbstractThis note supplements an earlier paper of this author, in which the concept of a strong k-hypomorphism between two graphs was defined (Thatte, 1990, Sectin VI). For k=1, this is just a hypomorphism. Here it is proved that strongly k-hypomorphic graphs and strongly k-edge hypomorphic directed graphs are isomorphic if k>1
A role for the region encompassing the c'' strand of a TCR Vα domain in T cell activation events
No full textThe distinct strand topology of TCR Vα domains results in a flatter surface in the region encompassing the c' strand than the corresponding region in Ig V domains. In the current study a possible role for this region in T cell activation has been investigated by inserting a potential glycosylation site at Vα residue 82. This residue is in proximity to the c'' strand and distal to the putative interaction site for cognate peptide:MHC ligand. An additional N-linked carbohydrate at this position would create a protrusion on the Vα domain surface, and this may interfere with TCR aggregation and/or recruitment of signaling molecules. The modified TCR has been expressed in transfected T cells, and the phenotype following stimulation has been compared with that of cells expressing the wild-type TCR. The mutation has significant effects on activation-induced cell death and TCR internalization, but, unexpectedly, does not affect IL-2 secretion. Furthermore, analyses with tetrameric, peptide:MHC class II complexes suggest that the mutation decreases the ability of the TCR to aggregate into a configuration compatible with avid binding by these multivalent ligands.</p
A reconstruction problem related to balance equations II: The general case
No full textAbstractA modified k-deck of a graph G, first introduced in (Krasikov and Roditty, 1987), is obtained by removing k edges of G in all possible ways, and adding k (not necessarily new) edges in all possible ways. Krasikov and Roditty asked if it was possible to construct the usual k-edge deck of a graph from its modified k-deck. In (Thatte, to appear), the author solved this problem for the case when k = 1. In this paper, the problem is completely solved for arbitrary k. The proof makes use of the k-edge version of Lovász's result and the eigenvalues of certain matrix related to the Johnson graph
Abstract 4707: Evaluation of efficacy and immune response to PD1 checkpoint inhibition in human immune-reconstituted mice using patient-derived xenograft models
No full textAbstract
Background: Human Immune-reconstituted Mice, generated by transplanting pre-validated human CD34+ hematopoietic stem cells (HSC) into immune-compromised mice, are extremely useful in basic and applied human disease research. Many cancer therapies, including immune checkpoint inhibitors such as the anti-PD-1 monoclonal antibody, rely on an intact immune system to release immunosuppression and destroy cancer cells.
Material and methods: We evaluated the effects of anti-PD-1 in humanized mice in donor cohorts utilizing the cancer matrix of 5 HSC donor cohorts of humanized animals with PDX models from 7 small cell lung cancer (SCLC). We also tested anti-PD-1 in 1 triple negative breast cancer (TNBC) model and in 1 MDA-MB-231 study.
Results: Here, we show that HSC derived human immune cell engraftment does not have significant effects on patient derived xenograft (PDX) tumor growth. However, humanization is required for anti-tumor response to anti-PD-1. In MDA-MB-231 study, tumors showed complete regression after the first round of treatment. Re-engraftment of same animals with MDA-MB-231 cells showed minor tumor growth before complete regression again. Aged match control naïve animals engrafted with same cells showed normal tumor growth. In SCLC studies anti-PD-1 efficacy varied between the models, which clearly underscores the inherent donor to donor variability in this humanized model system. Tumors from these studies were then analyzed to determine target engagement of anti-PD-1, tumor infiltrating lymphocytes (TILs) characterization and histology comparing anti-PD-1 responders vs non-responders. As expected, in this study, we demonstrate humanization of the animals is necessary to evaluate the efficacy of anti-PD-1 therapy and can elicit an immunotherapy mediated anti-tumor effect.
Conclusion: Here we demonstrate the development of humanized mouse studies with ability to run multi point analysis to determine the outcome of treatment.
Citation Format: Hooman Izadi, Tommy Broudy, Deborah Yan, Jayant Thatte. Evaluation of efficacy and immune response to PD1 checkpoint inhibition in human immune-reconstituted mice using patient-derived xenograft models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4707. doi:10.1158/1538-7445.AM2017-4707</jats:p
Fault Diagnosis of Semiconductor Random Access Memories
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Reason: Restricted to UIUC communityOpen Restriction set for Item 100821 on 2019-11-15T17:33:23Z with date null by [email protected] Services Electronics Program / DAAB-07-72-C-0259OpenCoordinated Science Laboratory was formerly known as Control Systems Laboratory"Author name appears as ""Satish Munkund Thatte"" in front matter
Provenance-based trust for grid computing: Position Paper
No full textCurrent evolutions of Internet technology such as Web Services, ebXML, peer-to-peer and Grid computing all point to the development of large-scale open networks of diverse computing systems interacting with one another to perform tasks. Grid systems (and Web Services) are exemplary in this respect and are perhaps some of the first large-scale open computing systems to see widespread use - making them an important testing ground for problems in trust management which are likely to arise. From this perspective, today's grid architectures suffer from limitations, such as lack of a mechanism to trace results and lack of infrastructure to build up trust networks. These are important concerns in open grids, in which "community resources" are owned and managed by multiple stakeholders, and are dynamically organised in virtual organisations. Provenance enables users to trace how a particular result has been arrived at by identifying the individual services and the aggregation of services that produced such a particular output. Against this background, we present a research agenda to design, conceive and implement an industrial-strength open provenance architecture for grid systems. We motivate its use with three complex grid applications, namely aerospace engineering, organ transplant management and bioinformatics. Industrial-strength provenance support includes a scalable and secure architecture, an open proposal for standardising the protocols and data structures, a set of tools for configuring and using the provenance architecture, an open source reference implementation, and a deployment and validation in industrial context. The provision of such facilities will enrich grid capabilities by including new functionalities required for solving complex problems such as provenance data to provide complete audit trails of process execution and third-party analysis and auditing. As a result, we anticipate that a larger uptake of grid technology is likely to occur, since unprecedented possibilities will be offered to users and will give them a competitive edge
Abstract 4203: Kinase inhibitor demonstrates efficacy in patient derived xenograft model of fibrolamellar hepatocellular carcinoma featuring DNAJB1-PRKACA gene fusion
No full textAbstract
Fibrolamellar hepatocellular carcinoma (FL-HCC) is a rare and distinct primary hepatic malignancy that has conventionally been considered to be a histologic variant of hepatocellular carcinoma. However, it has more recently been recognized as a distinct clinical entity with respect to its epidemiology and prognosis. The etiology of FL-HCC is unclear and there is no clinical or histological evidence for association with chronic liver disease. Recent genetic studies have identified the fusion gene DNAJB1-PRKACA as a recurrent genetic lesion in the disease. Molecular pathogenesis of FL-HCC; however, is not well understood and has been reported to occur in association with focal nodular hyperplasia. Overexpression of genes in PIK3, MAPK and RAS pathways is observed in FL-HCC and in contrast to viral-associated HCC, epigenetic instability is rare in FL-HCC.
Here we describe development of a novel FL-HCC Patient Derived Xenograft (PDX) model LI5132. RNASeq analysis revealed presence of DNAJB1-PRKACA gene fusion on chromosome 19, a molecular signature of FL-HCC. Clinical diagnosis as HCC of fibrolamellar type was confirmed by H&E staining in the PDX tumor. The PDX tumor had a distinctive intratumoral fibrosis with a lamellar pattern. PDX model was established by inoculating patient tumor cells subcutaneously in NOD-SCID mice. Robust tumor growth was observed with a 100% take rate in NOD-SCID mice.
To evaluate the translational relevance of this model toward therapeutic development, the efficacy of a novel multi-target Aurora kinase A and angiokinase inhibitor, ENMD-2076, was evaluated in a therapeutic mode in this model. ENMD-2076 showed significant efficacy in suppressing tumor growth in NOD-SCID mice, at the 200 mg/kg dose evaluated in this study. Weight loss observed during the treatment period could not be attributed to ENMD-2076 as it was similar to weight loss observed with vehicle treatment. ENMD-2076 has now progressed in to phase II trials in the clinic for treatment of FL-HCC. This demonstrates the translational utility of this FL-HCC model in development of anti-cancer therapeutic agents.
Citation Format: Jayant Thatte, Elvira C. Talaoc, Colleen Scott, Ken Ren, Thomas Broudy. Kinase inhibitor demonstrates efficacy in patient derived xenograft model of fibrolamellar hepatocellular carcinoma featuring DNAJB1-PRKACA gene fusion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4203. doi:10.1158/1538-7445.AM2017-4203</jats:p
