C. Beers - Academia.edu (original) (raw)

Papers by C. Beers

Research paper thumbnail of Thymocyte expression of cathepsin L is essential for NKT cell development

Nature Immunology, 2002

CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell re... more CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell receptor V α 14J α 18 requires CD1d trafficking through endosomal compartments; however, the endosomal events remain undefined.We show that mice lacking the endosomal protease cathepsin L (catL) have greatly reduced numbers of V α 14 + NK1.1 + T cells. In addition, catL expression in thymocytes is critical not only for selection of these cells in vivo but also for stimulation of V α 14 + NK1.1 + T cells in vitro. CD1d cell-surface expression and intracellular localization appear normal in catL-deficient thymocytes, as does the lysosomal morphology; this implies a specific role for catL in regulating presentation of natural CD1d ligands mediating V α 14 + NK1.1 + T cell selection.These data implicate lysosomal proteases as key regulators of not only classical major histocompatibility complex class II antigen presentation but also nonclassical CD1d presentation.

Research paper thumbnail of Cloning of a T Cell Growth Factor that Interacts with the β Chain of the Interleukin-2 Receptor

Science, 1994

A cytokine was identified that stimulated the proliferation of T lymphocytes, and a complementary... more A cytokine was identified that stimulated the proliferation of T lymphocytes, and a complementary DNA clone encoding this new T cell growth factor was isolated. The cytokine, designated interleukin-15 (IL-15), is produced by a wide variety of cells and tissues and shares many biological properties with IL-2. Monoclonal antibodies to the beta chain of the IL-2 receptor inhibited the biological activity of IL-15, and IL-15 competed for binding with IL-2, indicating that IL-15 uses components of the IL-2 receptor.

Research paper thumbnail of Positive selection of self-MHC-reactive T cells by individual peptide–MHC class II complexes

Proceedings of the National Academy of Sciences, 2002

If T cells require specific interactions with MHC-bound peptides during positive selection, then ... more If T cells require specific interactions with MHC-bound peptides during positive selection, then the specificities of T cells selected by one peptide should be distinct from those selected by another. We have examined positive selection of CD4 T cells in four strains of mice, each overexpressing a different peptide–1-A b (A b ) complex. We show that a subset of CD4 T cells is selected by the overexpressed peptide and that the specificities of the CD4 T cells, as measured by reactivity to wild-type antigen-presenting cells, vary greatly depending on which peptide is overexpressed. These differences in specificity are mediated through positive selection not negative selection. Each of the four peptide–A b complexes appears to adopt a different conformation, and these differences correlate with the differences in reactivity. Our results suggest that individual peptide–MHC complexes positively select different subsets of self-MHC-reactive T cells and that the conformation of the peptide...

Research paper thumbnail of Fas Ligand Costimulates the In Vivo Proliferation of CD8+ T Cells

The Journal of Immunology, 2000

Fas ligand (FasL/CD95L/APO-1L) is one of a growing number of TNF family members whose triggering ... more Fas ligand (FasL/CD95L/APO-1L) is one of a growing number of TNF family members whose triggering costimulates maximal proliferation of activated T cells. In this study we show that maximal Ag-dependent accumulation of transferred TCR-transgenic CD8+ T cells requires Fas (CD95/APO-1) expression by the adoptive hosts. Additionally, adoptively transferred FasL+ CD8+ T cells demonstrate a 2-fold advantage in Ag-driven expansion over their FasL−counterparts. This study illustrates the in vivo role of TCR-dependent FasL costimulation in the Ag-specific proliferation of both heterogeneous and homogeneous populations of primary CD8+ T cells and long-term CTL lines. Thus, cross-linking FasL on naive and Ag-experienced CD8+ T cells whose Ag-specific TCRs are engaged is required to drive maximal cellular proliferation in vivo.

Research paper thumbnail of Down-Regulation of the Orphan Nuclear Receptor RORγt Is Essential for T Lymphocyte Maturation

The Journal of Immunology, 2000

Thymocyte development is a tightly regulated process. CD4+CD8+ double-positive (DP) immature thym... more Thymocyte development is a tightly regulated process. CD4+CD8+ double-positive (DP) immature thymocytes exhibit distinct phenotypic features from mature T cells; they express only 10% of surface TCR that are found on mature T cells and do not proliferate and produce IL-2 in response to stimulation. In this report we show that transgenic expression of the orphan nuclear receptor RORγt in mature T cells down-regulates their surface TCR expression. The RORγt transgene inhibits IL-2 production by mature T cells, and this inhibition may be partially due to the inhibitory effect of RORγt on c-Rel transcription. Furthermore, ectopic expression of RORγt inhibits the proliferation of mature and immature T cells. These results, together with its predominant expression in DP thymocytes, suggest that RORγt controls these distinct phenotypic features of DP thymocytes. Our data suggest that down-regulation of RORγt expression in thymocytes is essential for their maturation.

Research paper thumbnail of A Role for Cathepsin L and Cathepsin S in Peptide Generation for MHC Class II Presentation

The Journal of Immunology, 2002

The enzymes that degrade proteins to peptides for presentation on MHC class II molecules are poor... more The enzymes that degrade proteins to peptides for presentation on MHC class II molecules are poorly understood. The cysteinal lysosomal proteases, cathepsin L (CL) and cathepsin S (CS), have been shown to process invariant chain, thereby facilitating MHC class II maturation. However, their role in Ag processing is not established. To examine this issue, we generated embryonic fibroblast lines that express CL, CS, or neither. Expression of CL or CS mediates efficient degradation of invariant chain as expected. Ag presentation was evaluated using T cell hybridoma assays as well as mass spectroscopic analysis of peptides eluted from MHC class II molecules. Interestingly, we found that the majority of peptides are presented regardless of CL or CS expression, although these proteases often alter the relative levels of the peptides. However, for a subset of Ags, epitope generation is critically regulated by CL or CS. This result suggests that these cysteinal proteases participate in Ag pr...

Research paper thumbnail of Differential Regulation of Cathepsin S and Cathepsin L in Interferon γ–treated Macrophages

Journal of Experimental Medicine, 2003

Cathepsin S (catS) and cathepsin L (catL) mediate late stages of invariant chain (Ii) degradation... more Cathepsin S (catS) and cathepsin L (catL) mediate late stages of invariant chain (Ii) degradation in discrete antigen-presenting cell types. Macrophages (Mϕs) are unique in that they express both proteases and here we sought to determine the relative contribution of each enzyme. We observe that catL plays no significant role in Ii cleavage in interferon (IFN)-γ–stimulated Mϕs. In addition, our studies show that the level of catL activity is significantly decreased in Mϕs cultured in the presence of IFN-γ whereas catS activity increases. The decrease in catL activity upon cytokine treatment occurs despite the persistence of high levels of mature catL protein, suggesting that a specific inhibitor of the enzyme is up-regulated in IFN-γ–stimulated peritoneal Mϕs. Similar inhibition of activity is observed in dendritic cells engineered to overexpress catL. Such enzymatic inhibition in Mϕs exhibits only partial dependence upon Ii and therefore, other mechanisms of catL inhibition are regu...

Research paper thumbnail of Structure-Function Studies of Interleukin 15 using Site-specific Mutagenesis, Polyethylene Glycol Conjugation, and Homology Modeling

Journal of Biological Chemistry, 1997

Interleukin (IL)-15 is a multifunctional cytokine that shares many biological activities with IL-... more Interleukin (IL)-15 is a multifunctional cytokine that shares many biological activities with IL-2. This functional overlap, as well as receptor binding subunits shared by IL-15 and IL-2, suggests tertiary structural similarities between these two cytokines. In this study, recombinant human IL-15 was PEGylated via lysine-specific conjugation chemistry in order to extend the circulation half-life of this cytokine. Although PEGylation did extend the ␤-elimination circulation half-life of IL-15 by greater than 50-fold, the biological activity of polyethylene glycol (PEG)-IL-15 was significantly altered. Specifically, PEG-IL-15 lost its ability to stimulate the proliferation of CTLL but took on the properties of a specific IL-15 antagonist in vitro. In comparing sequence alignments and molecular models for IL-2 and IL-15, it was noted that lysine residues resided in regions of IL-15 that may have selectively disrupted receptor subunit binding. We hypothesized that PEGylation of IL-15 interferes with ␤ but not ␣ receptor subunit binding, resulting in the IL-15 antagonist activity observed in vitro. The validity of this hypothesis was tested by engineering site-specific mutants of human IL-15 as suggested by the IL-15 model (IL-15D8S and IL-15Q108S block ␤ and ␥ receptor subunit binding, respectively). As with PEG-IL-15, these mutants were unable to stimulate CTLL proliferation but were able to specifically inhibit the proliferation of CTLL in response to unmodified IL-15. These results supported our model of IL-15 and confirmed that interference of ␤ receptor subunit binding by adjacent PEGylation could be responsible for the altered biological activity observed for PEG-IL-15.

Research paper thumbnail of Cathepsin S Regulates the Expression of Cathepsin L and the Turnover of γ-Interferon-inducible Lysosomal Thiol Reductase in B Lymphocytes

Journal of Biological Chemistry, 2001

Research paper thumbnail of Dose escalation results from a first-in-human, phase 1 study of glucocorticoid-induced TNF receptor-related protein agonist AMG 228 in patients with advanced solid tumors

Journal for immunotherapy of cancer, Jan 25, 2018

This open-label, first-in-human, phase 1 study evaluated the safety, pharmacokinetics, pharmacody... more This open-label, first-in-human, phase 1 study evaluated the safety, pharmacokinetics, pharmacodynamics, and maximum tolerated dose (MTD) of AMG 228, an agonistic human IgG1 monoclonal antibody targeting glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR), in patients with refractory advanced solid tumors. AMG 228 was administered intravenously every 3 weeks (Q3W). Dose escalation was in two stages: single-patient cohorts (3, 9, 30, and 90 mg), followed by "rolling six" design (n = 2-6; 180, 360, 600, 900, and 1200 mg). Primary endpoints included incidence of dose-limiting toxicities (DLTs), AEs, and pharmacokinetics. Additional endpoints were objective response and pharmacodynamic response. Thirty patients received AMG 228, which was well tolerated up to the maximum planned dose (1200 mg). No DLTs occurred; the MTD was not reached. The most common treatment-related AEs were fatigue (13%), infusion-related reaction (7%), pyrexia (7%), decreased app...

Research paper thumbnail of Thymocyte expression of cathepsin L is essential for NKT cell development

Nature Immunology, 2002

CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell re... more CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell receptor V α 14J α 18 requires CD1d trafficking through endosomal compartments; however, the endosomal events remain undefined.We show that mice lacking the endosomal protease cathepsin L (catL) have greatly reduced numbers of V α 14 + NK1.1 + T cells. In addition, catL expression in thymocytes is critical not only for selection of these cells in vivo but also for stimulation of V α 14 + NK1.1 + T cells in vitro. CD1d cell-surface expression and intracellular localization appear normal in catL-deficient thymocytes, as does the lysosomal morphology; this implies a specific role for catL in regulating presentation of natural CD1d ligands mediating V α 14 + NK1.1 + T cell selection.These data implicate lysosomal proteases as key regulators of not only classical major histocompatibility complex class II antigen presentation but also nonclassical CD1d presentation.

Research paper thumbnail of Thymocyte expression of cathepsin L is essential for NKT cell development

Nature Immunology, 2002

CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell re... more CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell receptor V α 14J α 18 requires CD1d trafficking through endosomal compartments; however, the endosomal events remain undefined.We show that mice lacking the endosomal protease cathepsin L (catL) have greatly reduced numbers of V α 14 + NK1.1 + T cells. In addition, catL expression in thymocytes is critical not only for selection of these cells in vivo but also for stimulation of V α 14 + NK1.1 + T cells in vitro. CD1d cell-surface expression and intracellular localization appear normal in catL-deficient thymocytes, as does the lysosomal morphology; this implies a specific role for catL in regulating presentation of natural CD1d ligands mediating V α 14 + NK1.1 + T cell selection.These data implicate lysosomal proteases as key regulators of not only classical major histocompatibility complex class II antigen presentation but also nonclassical CD1d presentation.

Research paper thumbnail of Cloning of a T Cell Growth Factor that Interacts with the β Chain of the Interleukin-2 Receptor

Science, 1994

A cytokine was identified that stimulated the proliferation of T lymphocytes, and a complementary... more A cytokine was identified that stimulated the proliferation of T lymphocytes, and a complementary DNA clone encoding this new T cell growth factor was isolated. The cytokine, designated interleukin-15 (IL-15), is produced by a wide variety of cells and tissues and shares many biological properties with IL-2. Monoclonal antibodies to the beta chain of the IL-2 receptor inhibited the biological activity of IL-15, and IL-15 competed for binding with IL-2, indicating that IL-15 uses components of the IL-2 receptor.

Research paper thumbnail of Positive selection of self-MHC-reactive T cells by individual peptide–MHC class II complexes

Proceedings of the National Academy of Sciences, 2002

If T cells require specific interactions with MHC-bound peptides during positive selection, then ... more If T cells require specific interactions with MHC-bound peptides during positive selection, then the specificities of T cells selected by one peptide should be distinct from those selected by another. We have examined positive selection of CD4 T cells in four strains of mice, each overexpressing a different peptide–1-A b (A b ) complex. We show that a subset of CD4 T cells is selected by the overexpressed peptide and that the specificities of the CD4 T cells, as measured by reactivity to wild-type antigen-presenting cells, vary greatly depending on which peptide is overexpressed. These differences in specificity are mediated through positive selection not negative selection. Each of the four peptide–A b complexes appears to adopt a different conformation, and these differences correlate with the differences in reactivity. Our results suggest that individual peptide–MHC complexes positively select different subsets of self-MHC-reactive T cells and that the conformation of the peptide...

Research paper thumbnail of Fas Ligand Costimulates the In Vivo Proliferation of CD8+ T Cells

The Journal of Immunology, 2000

Fas ligand (FasL/CD95L/APO-1L) is one of a growing number of TNF family members whose triggering ... more Fas ligand (FasL/CD95L/APO-1L) is one of a growing number of TNF family members whose triggering costimulates maximal proliferation of activated T cells. In this study we show that maximal Ag-dependent accumulation of transferred TCR-transgenic CD8+ T cells requires Fas (CD95/APO-1) expression by the adoptive hosts. Additionally, adoptively transferred FasL+ CD8+ T cells demonstrate a 2-fold advantage in Ag-driven expansion over their FasL−counterparts. This study illustrates the in vivo role of TCR-dependent FasL costimulation in the Ag-specific proliferation of both heterogeneous and homogeneous populations of primary CD8+ T cells and long-term CTL lines. Thus, cross-linking FasL on naive and Ag-experienced CD8+ T cells whose Ag-specific TCRs are engaged is required to drive maximal cellular proliferation in vivo.

Research paper thumbnail of Down-Regulation of the Orphan Nuclear Receptor RORγt Is Essential for T Lymphocyte Maturation

The Journal of Immunology, 2000

Thymocyte development is a tightly regulated process. CD4+CD8+ double-positive (DP) immature thym... more Thymocyte development is a tightly regulated process. CD4+CD8+ double-positive (DP) immature thymocytes exhibit distinct phenotypic features from mature T cells; they express only 10% of surface TCR that are found on mature T cells and do not proliferate and produce IL-2 in response to stimulation. In this report we show that transgenic expression of the orphan nuclear receptor RORγt in mature T cells down-regulates their surface TCR expression. The RORγt transgene inhibits IL-2 production by mature T cells, and this inhibition may be partially due to the inhibitory effect of RORγt on c-Rel transcription. Furthermore, ectopic expression of RORγt inhibits the proliferation of mature and immature T cells. These results, together with its predominant expression in DP thymocytes, suggest that RORγt controls these distinct phenotypic features of DP thymocytes. Our data suggest that down-regulation of RORγt expression in thymocytes is essential for their maturation.

Research paper thumbnail of A Role for Cathepsin L and Cathepsin S in Peptide Generation for MHC Class II Presentation

The Journal of Immunology, 2002

The enzymes that degrade proteins to peptides for presentation on MHC class II molecules are poor... more The enzymes that degrade proteins to peptides for presentation on MHC class II molecules are poorly understood. The cysteinal lysosomal proteases, cathepsin L (CL) and cathepsin S (CS), have been shown to process invariant chain, thereby facilitating MHC class II maturation. However, their role in Ag processing is not established. To examine this issue, we generated embryonic fibroblast lines that express CL, CS, or neither. Expression of CL or CS mediates efficient degradation of invariant chain as expected. Ag presentation was evaluated using T cell hybridoma assays as well as mass spectroscopic analysis of peptides eluted from MHC class II molecules. Interestingly, we found that the majority of peptides are presented regardless of CL or CS expression, although these proteases often alter the relative levels of the peptides. However, for a subset of Ags, epitope generation is critically regulated by CL or CS. This result suggests that these cysteinal proteases participate in Ag pr...

Research paper thumbnail of Differential Regulation of Cathepsin S and Cathepsin L in Interferon γ–treated Macrophages

Journal of Experimental Medicine, 2003

Cathepsin S (catS) and cathepsin L (catL) mediate late stages of invariant chain (Ii) degradation... more Cathepsin S (catS) and cathepsin L (catL) mediate late stages of invariant chain (Ii) degradation in discrete antigen-presenting cell types. Macrophages (Mϕs) are unique in that they express both proteases and here we sought to determine the relative contribution of each enzyme. We observe that catL plays no significant role in Ii cleavage in interferon (IFN)-γ–stimulated Mϕs. In addition, our studies show that the level of catL activity is significantly decreased in Mϕs cultured in the presence of IFN-γ whereas catS activity increases. The decrease in catL activity upon cytokine treatment occurs despite the persistence of high levels of mature catL protein, suggesting that a specific inhibitor of the enzyme is up-regulated in IFN-γ–stimulated peritoneal Mϕs. Similar inhibition of activity is observed in dendritic cells engineered to overexpress catL. Such enzymatic inhibition in Mϕs exhibits only partial dependence upon Ii and therefore, other mechanisms of catL inhibition are regu...

Research paper thumbnail of Structure-Function Studies of Interleukin 15 using Site-specific Mutagenesis, Polyethylene Glycol Conjugation, and Homology Modeling

Journal of Biological Chemistry, 1997

Interleukin (IL)-15 is a multifunctional cytokine that shares many biological activities with IL-... more Interleukin (IL)-15 is a multifunctional cytokine that shares many biological activities with IL-2. This functional overlap, as well as receptor binding subunits shared by IL-15 and IL-2, suggests tertiary structural similarities between these two cytokines. In this study, recombinant human IL-15 was PEGylated via lysine-specific conjugation chemistry in order to extend the circulation half-life of this cytokine. Although PEGylation did extend the ␤-elimination circulation half-life of IL-15 by greater than 50-fold, the biological activity of polyethylene glycol (PEG)-IL-15 was significantly altered. Specifically, PEG-IL-15 lost its ability to stimulate the proliferation of CTLL but took on the properties of a specific IL-15 antagonist in vitro. In comparing sequence alignments and molecular models for IL-2 and IL-15, it was noted that lysine residues resided in regions of IL-15 that may have selectively disrupted receptor subunit binding. We hypothesized that PEGylation of IL-15 interferes with ␤ but not ␣ receptor subunit binding, resulting in the IL-15 antagonist activity observed in vitro. The validity of this hypothesis was tested by engineering site-specific mutants of human IL-15 as suggested by the IL-15 model (IL-15D8S and IL-15Q108S block ␤ and ␥ receptor subunit binding, respectively). As with PEG-IL-15, these mutants were unable to stimulate CTLL proliferation but were able to specifically inhibit the proliferation of CTLL in response to unmodified IL-15. These results supported our model of IL-15 and confirmed that interference of ␤ receptor subunit binding by adjacent PEGylation could be responsible for the altered biological activity observed for PEG-IL-15.

Research paper thumbnail of Cathepsin S Regulates the Expression of Cathepsin L and the Turnover of γ-Interferon-inducible Lysosomal Thiol Reductase in B Lymphocytes

Journal of Biological Chemistry, 2001

Research paper thumbnail of Dose escalation results from a first-in-human, phase 1 study of glucocorticoid-induced TNF receptor-related protein agonist AMG 228 in patients with advanced solid tumors

Journal for immunotherapy of cancer, Jan 25, 2018

This open-label, first-in-human, phase 1 study evaluated the safety, pharmacokinetics, pharmacody... more This open-label, first-in-human, phase 1 study evaluated the safety, pharmacokinetics, pharmacodynamics, and maximum tolerated dose (MTD) of AMG 228, an agonistic human IgG1 monoclonal antibody targeting glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR), in patients with refractory advanced solid tumors. AMG 228 was administered intravenously every 3 weeks (Q3W). Dose escalation was in two stages: single-patient cohorts (3, 9, 30, and 90 mg), followed by "rolling six" design (n = 2-6; 180, 360, 600, 900, and 1200 mg). Primary endpoints included incidence of dose-limiting toxicities (DLTs), AEs, and pharmacokinetics. Additional endpoints were objective response and pharmacodynamic response. Thirty patients received AMG 228, which was well tolerated up to the maximum planned dose (1200 mg). No DLTs occurred; the MTD was not reached. The most common treatment-related AEs were fatigue (13%), infusion-related reaction (7%), pyrexia (7%), decreased app...

Research paper thumbnail of Thymocyte expression of cathepsin L is essential for NKT cell development

Nature Immunology, 2002

CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell re... more CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell receptor V α 14J α 18 requires CD1d trafficking through endosomal compartments; however, the endosomal events remain undefined.We show that mice lacking the endosomal protease cathepsin L (catL) have greatly reduced numbers of V α 14 + NK1.1 + T cells. In addition, catL expression in thymocytes is critical not only for selection of these cells in vivo but also for stimulation of V α 14 + NK1.1 + T cells in vitro. CD1d cell-surface expression and intracellular localization appear normal in catL-deficient thymocytes, as does the lysosomal morphology; this implies a specific role for catL in regulating presentation of natural CD1d ligands mediating V α 14 + NK1.1 + T cell selection.These data implicate lysosomal proteases as key regulators of not only classical major histocompatibility complex class II antigen presentation but also nonclassical CD1d presentation.