CROSS REFERENCE TO RELATED APPLICATION
FIELD OF THE INVENTION
This application claims priority to U.S. Provisional Application Ser. No. 60/613,247, filed 27 Sep. 2004, the entire contents of which is incorporated herein by reference.
- BACKGROUND OF THE INVENTION
The present invention relates to mammalian sRAGE mimetibodies and their use as therapeutics.
The Receptor for Advanced Glycated Endproducts (RAGE) is a member of the immunoglobulin superfamily of cell-surface molecules.
It was originally identified and characterized as a cellular receptor for glucose (aldose sugar)-modified proteins or Advanced Glycated Endproducts (AGE) (Schmidt et al., J. Biol. Chem. 267: 14987-14997, (1992); Neeper et al., J. Biol. Chem. 267: 14998-15004, (1992)). AGE have been implicated in a variety of disorders associated with diabetes and aging (reviewed in Schmidt et al., Nature Med. 1: 1002-1004, (1995)). Binding of AGE to RAGE induces inflammatory responses in blood vessel walls, which can trigger or aggravate the pathogenesis of macro- or micro-angiopathy.
RAGE has also been reported to interact with other ligands, including amphoterin, a matrix-associated polypeptide that promotes outgrowth of cultured cortical neurons derived from developing brain (Hori et al., J. Biol. Chem. 270: 25752-25761, (1995)). Amphoterin, also known in the literature as high mobility group B1 (HMGB1), has been shown to contribute to a variety of disease states including cancer, inflammatory conditions and sepsis. See Lotze and DeMarco, Curr. Opin. Investig. Drugs 4: 1405-1409 (2003); Scaffidi et al., Nature 418: 191-195 (2002); and Wang et al., Science 285: 248-251 (1999). The expression of RAGE is markedly enhanced and co-localizes with that of amphoterin at the leading edge of advancing neurites, which indicates a potential contribution to cellular migration and in pathologies such as tumor invasion. It has been reported that either anti-RAGE F(ab′)2 or soluble RAGE inhibited neurite outgrowth on amphoterin-coated matrices (Taguchi et al., Nature 405: 354-360, (2000)). Soluble RAGE (sRAGE) is the extracellular domain of the receptor. In addition, blockade of RAGE-amphoterin binding decreased growth and metastases of both implanted tumors and tumors developing spontaneously in susceptible mice, Id.
RAGE has also been identified as a receptor on neurons and microglia for β-amyloid, a polypeptide linked to the pathogenesis of neuronal toxicity and death in Alzheimer's disease (Yan et al., Nature 382: 685-691 (1996)). Expression of RAGE is particularly increased in neurons close to deposits of β-amyloid peptide and to neurofibrillary tangles. In mice, RAGE mediates the transport of human β-amyloid-40 and -42 across the blood-brain barrier (Deane et al., Nature Med. 9: 907-913 (2003)). Inhibition of the RAGE-ligand interaction, either by anti-RAGE IgG or soluble RAGE, neither of which is transported across the blood-brain barrier, suppressed the accumulation of β-amyloid in brain parenchyma in a mouse model of Alzheimer's disease, Id.
RAGE is also a central cell surface receptor for S100A2 and related members of the S100/calgranulins superfamily (Hofmann et al., Cell 97: 889-901 (1999)). Interaction of S100A2 and cellular RAGE on endothelium, mononuclear phagocytes and lymphocytes triggers cellular activation and generation of key proinflammatory mediators. In murine models, blockade of S100A2/RAGE quenched delayed-type hypersensitivity and inflammatory colitis by arresting activation of central signaling pathways and expression of inflammatory gene mediators, Id.
Studies have also shown that binding of RAGE by a ligand triggers activation of key cell signaling pathways, such as p21(ras), MAP kinases, NF-κb, and cdc42/rac thereby reprogramming cellular properties. For example, upon ligand binding, RAGE initiates a signaling cascade that results in the translocation of NF-κb to the nucleus and increased expression of adhesion molecules, procoagulant molecules and inflammatory proteins (Kislinger et al., J. Biol. Chem. 274: 31740-31749 (1999)).
Studies have indicated that RAGE interacts with various molecules implicated in homeostasis, development, inflammation, and certain diseases such as Type 2 diabetes and Alzheimer's disease. Accordingly, it would generally be desirable to block or otherwise inhibit these interactions, when associated with a disease state, to treat or prevent the associated pathologies.
sRAGE has been shown to be efficacious in animal disease models for atherosclerosis, tumor growth and metastasis, colitis, delayed-type hypersensitivity, experimental allergic encephalomyelitis, and Alzheimers disease (Park et al., Nature Med. 4: 1025-1031 (1998); Taguchi et al., supra; Hofmann et al., supra; Yan et al., supra) and can be purified or expressed recombinantly. sRAGE lacks the transmembrane and extracellular domains of full-length RAGE and has three immunoglobulin-like regions: an N-terminal region most similar to an immunoglobulin variable domain (V domain) followed by two regions resembling immunoglobulin constant regions (C domains).
BRIEF DESCRIPTION OF THE DRAWINGS
SRAGE has been used extensively in vitro and in vivo to study RAGE-ligand interactions. However, the half-life of sRAGE in rats is 24 hours and therefore sRAGE itself is impractical as a therapeutic for disease. Further, an anti-RAGE IgG would have to bind and inhibit large amounts of RAGE normally expressed in tissues such as lung and may induce death of normal cells. Thus, a need exists for a modified sRAGE that will overcome the short half-life while retaining the AGE binding function of RAGE.
FIGS. 1A to 1E show sRAGE mimetibody binding to AGEs. The mimetibodies tested include 1A: V in IgG1 with C220A and L234A/L235A mutations (V-G1)(SEQ ID NO: 5); 1B: V—C—C in IgG1 with C220A and L234A/L235A mutations (VCC-G1)(SEQ ID NO: 3); 1C: V in IgG4 with S228P and P234A, L235A mutations (V-G4)(SEQ ID NO: 13); 1D: V—C in IgG4 with S228P and P234A/L235A mutations (VC-G4)(SEQ ID NO: 11); and 1E: V—C—C in IgG4 with S228P and P234A/L235A mutations (VCC-G4)(SEQ ID NO: 9).
FIG. 2 shows the reduction of AGE binding to U937 cells by sRAGE mimetibodies.
- SUMMARY OF THE INVENTION
FIGS. 3A to 3E show sRAGE mimetibody inhibition of AGE-induced mRNA expression for tissue factor (FIG. 3A); VEGF (FIG. 3B); E-selectin (FIG. 3C); RAGE (FIG. 3D); and IL-6 (FIG. 3E).
One aspect of the invention is a polypeptide having the generic formula (II):
(Rg-Lk-V2—Hg—CH2—CH3) (t) (II)
where Rg is a mammalian sRAGE sequence, Lk is a polypeptide or chemical linkage, V2 is a portion of a C-terminus of an immunoglobulin variable region, Hg is at least a portion of an immunoglobulin variable hinge region, CH2 is an immunoglobulin heavy chain CH2 constant region and CH3 is an immunoglobulin heavy chain CH3 constant region and t is independently an integer from 1 to 10.
Another aspect of the invention is a polypeptide comprising a polypeptide having the sequence shown in SEQ ID NO: 3, 5, 7, 9, 11 or 13.
Another aspect of the invention is a polynucleotide comprising a polynucleotide having the sequence shown in SEQ ID NO: 4, 6, 8, 10, 12 or 14 or a complementary sequence.
Another aspect of the invention is a polynucleotide comprising a polynucleotide encoding the amino acid sequence shown in SEQ ID NO: 3, 5, 7, 9, 11 or 13.
Another aspect of the invention is a method of modifying the biological activity of RAGE in a mammal comprising administering an sRAGE mimetibody composition to the mammal.
- DETAILED DESCRIPTION OF THE INVENTION
Another aspect of the invention is a method of reducing the symptoms of, or treating at least one RAGE-related condition or disorder, comprising administering an sRAGE mimetibody composition to a patient in need thereof.
All publications, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference as though fully set forth. Single letter amino acid codes are used herein as understood by those skilled in the art. Numbering of amino acid residues in immunoglobulin constant regions is based on residue one being the N-terminal amino acid in a wild type IgG1 or IgG4 Fc domain.
The present invention provides polypeptides having the properties and activities of mammalian sRAGE wherein the polypeptides also mimic different types of immunoglobulin molecules such as IgA, IgD, IgE, IgG, or IgM, and any subclass thereof, such as IgA1, IgA2, IgG1, IgG2, IgG3 or IgG4, or combinations thereof, hereinafter referred to as “sRAGE mimetibodies.” The invention also provides nucleic acids encoding sRAGE mimetibodies, vectors containing these nucleic acids, host cells, compositions and methods of making and using sRAGE mimetibodies.
Mimetibody Polypeptides and Compositions
The present invention generally relates to mimetibody polypeptides having the generic formula (I):
(Pep-Lk-V2-Hg—CH2—CH3) (t) (I)
where Pep is a polypeptide having a desired biological property, Lk is a polypeptide or chemical linkage, V2 is a portion of a C-terminus of an immunoglobulin variable region, Hg is at least a portion of an immunoglobulin hinge region, CH2 is an immunoglobulin heavy chain CH2 constant region and CH3 is an immunoglobulin heavy chain CH3 constant region and t is independently an integer of 1 to 10.
More particularly, the present invention relates to sRAGE mimetibody polypeptides that are capable of blocking or reducing interactions between RAGE and its respective ligands such as AGE, amphoterin, S100/calgranulin and β-amyloid. The polypeptides have the generic formula (II):
(Rg-Lk-V2—Hg—CH2—CH3) (t) (II)
where Rg is a mammalian sRAGE sequence, Lk is a polypeptide or chemical linkage, V2 is a portion of a C-terminus of an immunoglobulin variable region, Hg is at least a portion of an immunoglobulin hinge region, CH2 is an immunoglobulin heavy chain CH2 constant region and CH3 is an immunoglobulin heavy chain CH3 constant region and t is independently an integer of 1 to 10.
As used herein, “soluble RAGE” or “sRAGE” encompasses RAGE-derived polypeptides that lack the transmembrane and intracellular regions associated with full-length RAGE. An exemplary mammalian sRAGE polypeptide is the extracellular domain of human sRAGE having the amino acid sequence shown in SEQ ID NO: 1. It is readily understood by those skilled in the art that sRAGE polypeptides can also include biologically active fragments of SEQ ID NO: 1, amino acid sequences that are substantially homologous to SEQ ID NO: 1 as well as polypeptides that can mimic the binding activity of sRAGE. It will also be understood by those skilled in the art that the mammalian sRAGE polypeptides useful in the present invention can include a native N-terminal leader sequence (amino acids 1-30 of SEQ ID NO: 1) or other leader sequence to facilitate excretion of the polypeptides of the invention from their production cell line.
The term “biologically active fragment” as used herein, refers to portions of sRAGE polypeptides that can specifically bind to an sRAGE ligand. Examples of biologically active fragments of sRAGE include, but are not limited to, one or more of the Ig-like domains, such as the single V domain (amino acids 31-106 of SEQ ID NO: 1), the V domain and a C domain (amino acids 31-215 of SEQ ID NO: 1), or the V domain and both C domains (amino acids 31-308 of SEQ ID NO: 1).
The term “substantially homologous” in the context of polypeptides, refers to two amino acid sequences which, when optimally aligned, are at least about 80% homologous or at least about 85% homoglous or at least about 90% homoglous or at least about 95% homologous. Alignment for purposes of determining percent amino acid homology can be achieved in various ways that are within the skill in the art, for example, by using the default settings for the AlignX component of Vector NTI Suite 8.0 (Informax, Frederick, Md.) or publicly available computer software such as BLAST (Altschul et al., J. Mol. Biol. 215: 403-410 (1990)). A polypeptide sequence substantially homologous to SEQ ID NO: 1 has at least one amino acid substitution, deletion or insertion.
In the polypeptides of the invention, the linker portion (Lk) provides structural flexibility by allowing the mimetibody to have alternative orientations and binding properties. Exemplary linkers include non-peptide chemical linkages or one to 20 amino acids linked by peptide bonds, wherein the amino acids are selected from the 20 naturally occurring amino acids. The linker portion can include a majority of amino acids that are sterically unhindered, such as glycine, alanine and serine and include GS, poly GS, GGGS (SEQ ID NO: 32), polymers of GGGS and GSGGGS (SEQ ID NO: 33) or any combination thereof. Other exemplary linkers within the scope of the invention may be longer than 20 residues and may include residues other than glycine, alanine and serine.
In the polypeptides of the invention, V2 is a portion of a C-terminal domain of an immunoglobulin variable region such as a heavy chain variable region. An exemplary V2 amino acid sequence is GTLVTVSS (SEQ ID NO: 16).
In the polypeptides of the invention, Hg is a portion of the hinge domain of an immunoglobulin variable region such as a heavy chain variable region. Exemplary H amino acid sequences include EPKSCDKTHTCPPCP (SEQ ID NO: 17), EPKSADKTHTCPPCP (SEQ ID NO: 18), ESKYGPPCPSCP (SEQ ID NO: 19), ESKYGPPCPPCP (SEQ ID NO: 20) and CPPCP (SEQ ID NO: 21).
In the polypeptides of the invention, CH
2 is an immunoglobulin heavy chain CH
2 constant region. Exemplary CH
2 amino acid sequences include:
|(SEQ ID NO: 22) || |
|APELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVD || |
|(SEQ ID NO: 23) || |
|APEAAGGPSVFLFPPKPKDTLNISRTPEVTCVVVDVSHEDPEVKFNWYVD || |
|(SEQ ID NO: 25) || |
|APEFLGGPSVFLFPPKPKDTLNISRTPEVTCVVVDVSQEDPEVQFNWYVD || |
|(SEQ ID NO: 26) || |
|APEAAGGPSVFLFPPKPKDTLNISRTPEVTCVVVDVSQEDPEVQFNWYVD || |
In the polypeptides of the invention, CH
3 is an immunoglobulin heavy chain CH
3 constant region. Exemplary CH
3 amino acid sequences include:
|(SEQ ID NO: 24) || |
|GQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENN || |
|(SEQ ID NO: 27) || |
|GQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENN || |
It will be recognized by those skilled in the art that the CH
3 region of the polypeptides of the invention may have its C-terminal amino acid cleaved off when expressed in certain recombinant systems.
In the polypeptides of the invention, the FcRn scavenger receptor binding site of the immunoglobulin molecules is preserved at the junction of the CH2 and CH3 region. Since FcRn binding enables the return of pinocytosed immunoglobulin back to the extracellular space, it is expected that the half-life of sRAGE mimetibodies will be significantly extended relative to sRAGE.
The polypeptides of the invention can optionally comprise, at their N-terminal, a portion of an N-terminus of an immunoglobulin variable region, designated V1 as shown in Formula III. Exemplary V1 amino acid sequences include QIQ or QVQ.
(V1-Rg-Lk-V2—Hg—CH2—CH3) (t) (III)
In one embodiment of the polypeptides of the invention, the monomeric structure (Rg-Lk-V2—Hg—CH2—CH3) can be linked to other monomers non-covalently or by covalent linkage, such as, but not limited to, a Cys-Cys disulfide bond. It is thought that this structure will allow stable dimerization of sRAGE and increase its affinity to RAGE ligands.
Another embodiment of the present invention is a polypeptide comprising a polypeptide according to formula (II) where Rg is a single copy of the RAGE full-length extracellular domain (SEQ ID NO: 1), V2 is a J region of a naturally occurring IgG (SEQ ID NO: 16), Hg is a complete IgG1 hinge region with a Cys220Ala (C220A) substitution (SEQ ID NO: 18) and CH2 and CH3 are of the IgG1 isotype subclass with Leu234Ala and Leu235Ala substitutions (L234A/L235A) (SEQ ID NO: 28). The complete polypeptide sequence of this embodiment is shown in SEQ ID NO: 3.
Another embodiment of the present invention is a polypeptide comprising a polypeptide according to formula (II) where Rg is a single copy of the V domain of the RAGE full-length extracellular domain (residues 31 to 106 of SEQ ID NO: 1), V2 is a J region of a naturally occurring IgG (SEQ ID NO: 16), Hg is a complete IgG1 hinge region with a C220A substitution (SEQ ID NO: 18) and CH2 and CH3 are of the IgG1 isotype subclass with L234A/L235A substitutions (SEQ ID NO: 28). The complete polypeptide sequence of this embodiment is shown in SEQ ID NO: 5.
Another embodiment of the present invention is a polypeptide comprising a polypeptide according to formula (II) where Rg is a single copy of the RAGE full-length extracellular domain (SEQ ID NO: 1), V2 is a J region of a naturally occurring IgG (SEQ ID NO: 16), Hg is the complete IgG4 hinge region (SEQ ID NO: 19) and CH2 and CH3 are of the IgG4 isotype subclass (SEQ ID NO: 29). The complete polypeptide sequence of this embodiment is shown in SEQ ID NO: 7.
IgG1 and IgG4 subclasses differ in the number of cysteines in the hinge region. Like the IgG1 subclass, there are two cysteines in the IgG4 hinge that participate in the disulfide bonding between heavy chains. However, the cysteine in IgG1 hinge that is normally involved in disulfide bonding to the light chain is absent in the IgG4 hinge. Therefore, the IgG4 hinge is less flexible than the IgG1 hinge.
In addition, the two isotypes differ in their ability to mediate complement dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). CDC is the lysing of a target in the presence of complement. The complement activation pathway is initiated by the binding of the first component of the complement system (C1q) to a molecule complexed with a cognate antigen. IgG1 is a strong inducer of the complement cascade and subsequent CDC activity, while IgG4 has little complement-inducing activity.
ADCC is a cell-mediated reaction in which nonspecific cytotoxic cells that express Fc receptors (FcRs) (e.g., Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cell. The IgG1 subclass binds with high affinity to the Fc receptor and contributes to ADCC while IgG4 binds only weakly. The relative inability of IgG4 to activate effector functions is desirable since delivery of the mimetibody to cells without cell killing is possible.
Furthermore, the binding site for the FcRn scavenger receptor is present in IgG4 and IgG1 isotypes and both have similar binding characteristics. Therefore, the pharmacokinetics of the IgG1 and IgG4 mimetibodies of the invention are expected to be similar.
The hinge-CH2—CH3 portion of the immunoglobulin region (Hg—CH2—CH3) may also be extensively modified to form variants in accordance with the invention. For example, one or more native sites that provide structural features or functional activity not required by the mimetibody molecules could be removed. These sites may be removed by, for example, substituting or deleting residues, inserting residues into the site, or truncating portions containing the site. Exemplary Hg—CH2—CH3 variants are discussed below.
1. Sites involved in disulfide bond formation can be removed by deletion or substitution with other amino acids in the mimetibodies of the invention. Typically, the cysteine residues present in these motifs are removed or substituted. Removal of these sites may avoid disulfide bonding with other cysteine-containing proteins present in the mimetibody-producing host cell or intra-heavy chain disulfide bonding in IgG4-based constructs while still allowing for a dimeric CH3—CH2-hinge domain that is held together non-covalently.
Most IgG type antibodies, such as IgG1, are homodimeric molecules made up of two identical heavy (H) chains and two identical light (L) chains, typically abbreviated H2L2. Thus, these molecules are generally bivalent with respect to antigen binding, i.e., both antigen binding (Fab) arms of the IgG molecule have identical binding specificity.
IgG4 isotype heavy chains contain a CPSC (SEQ ID NO: 15) motif in their hinge regions capable of forming either inter- or intra-heavy chain disulfide bonds, i.e., the two Cys residues in the CPSC motif may disulfide bond with the corresponding Cys residues in the other H chain (inter) or the two Cys residues within a given CPSC motif may disulfide bond with each other (intra). It is believed that in vivo isomerase enzymes are capable of converting inter-heavy chain bonds of IgG4 molecules to intra-heavy chain bonds and vice versa (Aalberse and Schuurman, Immunology 105, 9-19 (2002)).
Accordingly, since the HL pairs in those IgG4 molecules with intra-heavy chain bonds in the hinge region are not covalently associated with each other, they may dissociate into HL monomers that then reassociate with HL monomers derived from other IgG4 molecules forming bispecific, heterodimeric IgG4 molecules. In a bispecific IgG antibody the two Fabs of the antibody molecule differ in the epitopes that they bind. Substituting Ser228 in the hinge region of IgG4 with Pro results in “IgG1-like behavior,” i.e., the molecules form stable disulfide bonds between heavy chains and therefore, are not susceptible to HL exchange with other IgG4 molecules.
2. The H—CH2—CH3 can be modified to make the mimetibodies of the invention more compatible with a selected host cell. For example, when a mimetibody of the invention is expressed recombinantly in a bacterial cell such as E. coli, the Pro-Ala sequence in the hinge may be removed to prevent digestion by the E coli enzyme proline iminopeptidase.
3. A portion of the hinge region can be deleted or substituted with other amino acids in the mimetibodies of the invention to prevent heterogeneity in the products expressed in a selected host cell.
4. One or more glycosylation sites can be removed in the mimetibodies of the invention. Residues that are typically glycosylated (e.g., Asn) may confer an Fc-dependent, cell-mediated cytolytic activity to the mimetibody. Such residues may be deleted or substituted with residues that are not glycosylated such as Ala.
5. Sites involved in interaction with complement, such as the C1q binding site, are removed in the mimetibodies of the invention.
6. Sites can be removed that affect binding to Fc receptors other than a FcRn salvage receptor in the mimetibodies of the invention. For example, the Fc receptors involved in ADCC activity can be removed in the mimetibodies of the invention. For example, mutation of Leu234/Leu235 in the hinge region of IgG1 to L234A/L235A or Phe234/Leu235 in the hinge region of IgG4 to P234A/L235A minimizes FcR binding and reduces the ability of the immunoglobulin to mediate complement dependent cytotoxicity and ADCC.
One embodiment of the present invention is an sRAGE mimetibody according to formula (II) where the Hg—CH2—CH3 is from the IgG4 subclass (SEQ ID NO: 30) and contains a Ser228Pro (S228P) substitution and P234A/L235A mutations (SEQ ID NO: 31). The complete polypeptide sequences of exemplary sRAGE mimetibody polypeptides having these mutations and the (V—C—C), (V—C) and (V) domains of sRAGE, are shown respectively in SEQ ID NOs: 9, 11 and 13. These mimetibody constructs are expected be a homogeneous and stable population that does not trigger FcR-mediated effector functions. The substitution and mutations shown here are exemplary; Hg—CH2—CH3 domains within the scope of this invention may include other substitutions, mutations and/or deletions.
As mentioned above, the amino acid sequences of specific examples of mimetibodies of the invention are shown in SEQ ID NOs: 3, 5, 7, 9, 11 and 13. The characterstics of these constructs are shown in Table 1 (n.a.=not applicable).
|TABLE 1 |
|Exemplary mimetibody constructs |
|SEQ ||SRAGE ||Ig || || ||L234A/ ||P234A/ |
|ID NO: ||domains ||isotype ||C220A ||S228P ||L235A ||L235A |
|3 ||V-C-C ||IgG1 ||Yes ||n.a. ||Yes ||n.a. |
|5 ||V ||IgG1 ||Yes ||n.a. ||Yes ||n.a. |
|7 ||V-C-C ||IgG4 ||n.a. ||No ||n.a. ||No |
|9 ||V-C-C ||IgG4 ||n.a. ||Yes ||n.a. ||Yes |
|11 ||V-C ||IgG4 ||n.a. ||Yes ||n.a. ||Yes |
|13 ||V ||IgG4 ||n.a. ||Yes ||n.a. ||Yes |
The present invention includes sRAGE mimetibodies that are capable of blocking or reducing interactions between RAGE and at least one of its ligands. Embodiments of the invention include sRAGE mimetibodies that specifically bind to AGEs, amphoterin, S100/calgranulin or β-amyloid or any combination thereof. The mimetibodies of the present invention can bind RAGE ligands with a wide range of affinities. Exemplary sRAGE mimetibodies bind at least one RAGE ligand with high affinity. For example, an sRAGE mimetibody can bind at least one of AGEs, amphoterin, S100/calgranulin, β-amyloid or any combination thereof with a Kd equal to or less than about 10−7M, 10−8, 10−9, 10−10, 10−11 or 10−12M.
The affinity of an sRAGE mimetibody for a specific RAGE ligand can be determined experimentally using any suitable method, for example, methods using Biacore or KinExA instrumentation, ELISA and competitive binding assays. sRAGE mimetibodies having specific ligand binding capabilities can be selected from libraries of sRAGE variants or sRAGE fragments by techniques known to those skilled in the art.
The sRAGE mimetibodies of the present invention are useful in treating disorders or symptoms resulting from abnormal receptor activation of RAGE triggered by at least one ligand's binding. As described previously, the association of RAGE and its ligands has been implicated in a number of pathological conditions, such as but not limited to, Types 1 and 2 diabetes and Alzheimer's disease. Accordingly, another aspect of the present invention is pharmaceutical compositions comprising at least one sRAGE mimetibody and a pharmaceutically acceptable carrier or diluent known in the art. The carrier or diluent can be a solution, suspension, emulsion, colloid or powder.
An sRAGE mimetibody of the invention is formulated as a pharmaceutical composition in a therapeutically or prophylactically effective amount. The term “effective amount” generally refers to the quantities of mimetibody necessary for effective therapy, i.e., the partial or complete alleviation of the symptom or disorder for which treatment was sought. Included within the definition of effective therapy are prophylactic treatments intended to reduce the likelihood of onset of the above-described symptoms or disorders.
The composition can optionally comprise at least one further compound, protein or composition useful for treating the disease states discussed below. For example, combination with insulin, metformin, sulfonylureas or PPAR-γ agonists are contemplated in the treatment of Type 2 diabetes. Further, combination with anti-inflammatory agents to treat inflammatory disorders and combination with chemotherapy agents to treat cancer are also contemplated.
Nucleic Acids, Vectors and Cell Lines
Another aspect of the present invention is isolated nucleic acid molecules comprising, complementary to or having significant identity with a polynucleotide encoding at least one sRAGE mimetibody. Other aspects of the present invention include recombinant vectors comprising at least one isolated sRAGE mimetibody encoding nucleic acid molecule and cell lines and organisms that are capable of expressing the nucleic acid molecules.
The nucleic acids, expression vectors and cell lines may generally be used to produce the mimetibody of the invention.
In one embodiment, the nucleic acid compositions of the invention encode polypeptides having amino acid sequences identical to or substantially homologous to any one of SEQ ID NOs: 3, 5, 7, 9, 11 or 13. Exemplary nucleic acid sequences that encode the polypeptide sequences shown in SEQ ID NOs: 3, 5, 7, 9, 11 and 13 are shown in SEQ ID NOs: 4, 6, 8, 10, 12 and 14, respectively. Also provided are substantially similar nucleic acid sequences and allelic variations of the above-described nucleic acids.
The term “substantially similar” in the nucleic acid context, means that the segments, or their complementary strands, when properly aligned, with the appropriate nucleotide insertions or deletions, are identical in at least 60% or at least about 70% or at least about 80% or at least about 90% or at least about 95-98% of the nucleotides. Values for % identity can be obtained from nucleotide sequence alignments generated using the default settings for the AlignX component of Vector NTI Suite 8.0 (Informax, Frederick Md.).
Typically, the nucleic acids of the present invention are used in expression vectors for the preparation of the sRAGE mimetibody polypeptides of the invention. Vectors within the scope of the invention provide necessary elements for eukaryotic expression, including viral promoter driven vectors, such as CMV promoter driven vectors, e.g., pcDNA3.1, pCEP4 and their derivatives, Baculovirus expression vectors, Drosophila expression vectors and expression vectors that are driven by mammalian gene promoters, such as human Ig gene promoters. Other examples include prokaryotic expression vectors, such as T7 promoter driven vectors, e.g., pET41, lactose promoter driven vectors and arabinose gene promoter driven vectors.
The present invention also relates to cell lines expressing sRAGE mimetibodies. The host cells can be prokaryotic or eukaryotic cells. Exemplary eukaryotic cells are mammalian cells, such as but not limited to, COS-1, COS-7, HEK293, BHK21, CHO, BSC-1, HepG2, 653, SP2/0, NS0, 293, HeLa, myeloma, lymphoma cells, or any derivative thereof. Most preferably, the host cells are HEK293, NS0, SP2/0 or CHO cells. The cell lines of the present invention may stably express at least one sRAGE mimetibody. The cell lines may be generated by stable or transient transfection procedures that are well known in the art.
The present invention further provides methods for expressing at least one sRAGE mimetibody comprising culturing the cell lines under conditions wherein the sRAGE mimetibody is expressed in detectable or recoverable amounts. The present invention also provides methods for generating at least one sRAGE mimetibody comprising translating the sRAGE mimetibody encoding nucleic acids under conditions in vitro or in situ, such that the sRAGE mimetibody is expressed in detectable or recoverable amounts. The present invention also encompasses sRAGE mimetibodies produced by the above methods.
An sRAGE mimetibody can be recovered and purified by well-known methods including, but not limited to, protein A purification, ammonium sulfate or ethanol precipitation, acid extraction, anion or cation exchange chromatography, phosphocellulose chromatography, hydrophobic interaction chromatography, affinity chromatography, hydroxylatpatite chromatography and lectin chromatography. High performance liquid chroatography (HPLC) can also be employed for purification.
Methods of Use
The sRAGE mimetibodies are useful as, inter alia, research reagents and therapeutic agents. In one aspect, the present invention relates to a method of modifying the biological activities of RAGE comprising providing at least one sRAGE mimetibody to a mammal in need thereof. The sRAGE mimetibody may decrease or inhibit RAGE-activated cell signaling cascades, such as but not limited to the NF-Kb pathway. The sRAGE mimetibody of the invention can thus diminish the increased expression of adhesion molecules, procoagulant molecules and inflammatory proteins due to RAGE-initiated NF-Kb translocation into the nucleus. In particular, the sRAGE mimetibody may function as an antagonist of RAGE. The term “antagonist” is used in the broadest sense and includes a molecule that is capable of, directly or indirectly, partially or fully counteracting, reducing or inhibiting one or more biological activities of RAGE. Examples of such biological activites of RAGE include its binding to AGEs, amphoterin, Sl00/calgranulin or □-amyloid, activation of NF-□b, p21(ras), MAP kinases or cdc42/rac as well as other activities known to those skilled in the art.
The present invention further provides methods for reducing the symptoms of, or treating at least one RAGE-related condition or disease comprising administering a therapeutically effective amount of at least one sRAGE mimetibody pharmaceutical composition to a patient in need thereof. As described above, such composition comprises an effective amount of at least one sRAGE mimetibody and a pharmaceutically acceptable carrier or diluent. The effective amount for a given therapy, whether curative or preventative, will generally depend upon may different factors, including means of administration, target site and other medicants administered. Thus, treatment doses will need to be titrated to optimize safety and efficacy.
The conditions and diseases suitable for treatment using the methods of the present invention include but are not limited to, immune disorders, cardiovascular disorders, metabolic diseases, malignant disorders, and neurologic disorders. Non-limiting examples of these conditions or disorders are Types 1 and 2 diabetes, Alzheimer's disease, atherosclerosis, tumor growth and metastasis, inflammation, colitis, delayed type hypersensititvity, multiple sclerosis and aging related disorders such as oxidant stress. These methods can optionally further comprise co-administration or combination therapies with any standard therapy used to treat the diseases listed above.
The mode of administration can be any suitable route to deliver the pharmaceutically effective amount of sRAGE mimetibody of the present invention to a host. For example, the sRAGE mimetibody can be delivered via parenteral administration, such as subcutaneous, intramuscular, intradermal, intravenous or intranasal administration, or any other means known in the art.
Cloning, Expression and Purification of an sRAGE mimetibody in Mammalian Cells
The present invention is further described with reference to the following examples. These examples are merely to illustrate aspects of the present invention and are not intended as limitations of this invention.
Human sRAGE encoding cDNA was PCR amplified from human fetal lung 5′-STRETCH Plus cDNA Library (Clontech, Palo Alto, Calif.). The first round amplification was performed using forward primer 5′-GTCCCTGGAAGGAAGCAGG-3′ (SEQ ID NO: 34) and reverse primer 5′-TTTGGTACCCCTCAAGGCCCTCCAG-3′ (SEQ ID NO: 35).
A second round nested amplification was necessary to yield sufficient quantities of sRAGE cDNAs. The nested forward primers included an NcoI restriction enzyme recognition site and the nested reverse primers included a KpnI site. Specifically, the V region was amplified using forward primer 5′-TTTCCATGGCAGCCGGAACAGCAG-3′ (SEQ ID NO: 36) and reverse primer 5′-TTTGGTACCTCCATTCCTGTTCATTGCCTGG-3′ (SEQ ID NO: 37); and the V—C—C region was amplified using forward primer 5′-TTTCCATGGCAGCCGGAACAGCAG-3′ (SEQ ID NO: 36) and reverse primer 5′-TTTGGTACCGTGGCTGGAATGGGTGGCC-3′ (SEQ ID NO: 38).
The amplified PCR products (V region or V—C—C region of sRAGE) were cloned into the NcoI/KpnI site of an intermediate vector using standard cloning procedures. The EcoRI fragment of the assembled intermediate plasmids, containing promoter elements, enhancers and sRAGE encoding sequences were cloned into a mouse Ig gene promoter driven, human IgG1 ΔCH1 Ala/Ala expression vector. Plasmids expressing a V region containing sRAGE mimetibody and a V—C—C containing sRAGE mimetibody were generated.
The sRAGE IgG1 mimetibodies were stably expressed in mouse myeloma cells SP2/0 and purified from the conditioned media using protein A affinity chromatography according to standard procedures.
The sRAGE mimetibodies were also cloned into an IgG4 Ser to Pro, Ala/Ala scaffold. To amplify fragments encoding the V—C and the V—C—C sRAGE mimetibodies, the V—C—C containing plasmid was used as the template. The forward primers included an NheI site, and the reverse primers included a BamHI site. Specifically, the V—C region was amplified using forward primer 5′-TTTGCTAGCGCCACCATGGCAGCCGGAACAGCAGTT-3′ (SEQ ID NO: 39) and reverse primer 5′-TTTGGATCCGGGAAGGCCTGGGCTGAAGCTACA-3′ (SEQ ID NO: 40); and the the V—C—C region was amplified using forward primer 5′-TTTGCTAGCGCCACCATGGCAGCCGGAACAGCAGTT-3′ (SEQ ID NO: 39) and reverse primer 5′-TTTGGATCCGTGGCTGGAATGGGTGGCCACACA-3′ (SEQ ID NO: 41). The PCR products were digested using Nhe1 and BamH1. Because of an internal BamHI site in the V-like domain of RAGE, the PCR products were cleaved into two fragments using NheI/BamHI: one with nucleotides 1-275 of SEQ ID NO: 2, the other with nucleotides 276-645 (V—C product) or 276-924 (V—C—C product). Cloning of sRAGE mimetibody into the IgG4 expression vectors involved two steps. First, the 1-275 fragment was cloned into the NheI/BamHI site of human IgG4 ΔCH1, Ser to Pro, Ala/Ala expression vector to generate an intermediate plasmid. The 276-645 or the 276-924 fragment was subsequently cloned into the BamHI site of the intermediate plasmid to generate plasmid expressing V—C or V—C—C sRAGE mimetibody, respectively.
To clone the V-only region into the IgG4 Ser to Pro, Ala/Ala scaffold, PCR was performed using forward primer 5′-TTTGCTAGCGCCACCATGGCAGCCGGAACAGCAGTT-3′ (SEQ ID NO: 39) and reverse primer 5′-TTTGGATCCTCCATTCCTGTTCATTGCCTGGCACCGGAAAATCCCCTCATCCTGAATCCCGACAGCCG GAAGGAA-3′ (SEQ ID NO: 42). The NheI/BamHI digested PCR product was cloned into the NheI/BamHI site of human IgG4 ΔCH1, Ser to Pro, Ala/Ala expression vector in a single step.
- EXAMPLE 2
Binding of AGEs to sRAGE Mimetibody
The IgG4 mimetibodies were transiently expressed in HEK293E cells and purified from the conditioned media using protein A affinity chromatography according to standard procedures.
To prepare AGE, bovine serum albumin (BSA, Fraction V) (Sigma, St. Louis, Mo.) was incubated under non-reducing conditions with 50 mM glycoaldehyde in phosphate buffered saline (PBS) (pH 7.4) without calcium chloride or magnesium chloride for 3 days at 37° C. To terminate the reaction, the AGE were dialyzed with 10 volumes of PBS (pH 7.4). The final protein concentration was determined using the Bicinchoninic Acid based protein assay (Pierce, Rockford, Ill.). Samples were determined to contain less than 1 endotoxin unit (EU) per microgram of protein using Limulus amebocyte lysate (LAL) testing.
- EXAMPLE 3
SRAGE Mimetibody Reduces the Binding of AGE to RAGE
Solid phase ELISA was used to assess mimetibody binding to AGE. Briefly, 96-well plates were coated overnight with 30 ug/ml AGE in 0.1 M Carbonate buffer, pH9.5 at 37° C. After washing in 0.15 M saline buffer containing 0.02% (w/v) Tween-20, the wells were blocked with 1% (w/v) BSA, 0.05% Tween-20 in PBS for 2 hours at 37° C. After washing, plates were incubated with varying concentrations of sRAGE mimetibody diluted in PBS for 45 minutes at 37° C. Plates were washed and probed with HRP-labeled goat anti-human Fc (Jackson ImmunoResearch, West Groove, Pa.) diluted 1:1000 in 1% BSA/PBS for 20 minutes at 37° C. Following another washing step, plates were incubated for 15 minutes at room temperature with 100 μL/well of Sigma 104 Phosphate Substrate (Sigma). Substrate development was stopped by addition of 25 μL/well sulfuric acid (4N) and the absorbance was measured at 490 nm via an automated plate spectrophotometer. As shown in FIG. 1
, the mimetibodies tested all demonstrated binding to AGE. The binding affinities (KD) are shown in Table 2.
|TABLE 2 |
|Binding affinities (KD) of exemplary mimetibody constructs |
| ||SRAGE || ||KD |
|SEQ ID NO: ||domains ||Ig isotype ||(μg/ml) |
|3 ||V-C-C ||IgG1, C220A, L234A/L235A ||0.62 |
|5 ||V ||IgG1, C220A, L234A/L235A ||17.7 |
|9 ||V-C-C ||IgG4, S228P, P234A/L235A ||0.18 |
|11 ||V-C ||IgG4, S228P, P234A/L235A ||0.70 |
|13 ||V ||IgG4, Ser −> Pro, Ala/Ala ||0.89 |
To measure the binding of the AGE to RAGE, a 125-I binding assay was performed. Cells that express RAGE (U937 cells) were cultured in DMEM media with 10% FBS and 1% L-Glutamine, Na Pyruvate and non-essential amino acids at 37° C., 5% CO2, until 1.5×106 confluence was reached. Cells were plated in 96-well filter plates at 150,000 cells/well and incubated with 30 ug/ml Fc control (IgG4 mimetibody backbone without sRAGE encoding sequence) for 30 minutes at 37° C. to block Fc receptors. AGE were labeled with 125-I and the 125-I-AGEs were added to cells in two fold dilutions from 200 ug/ml to 0.1 ug/ml. After incubating at room temperature for 2 hours to allow maximal binding, the plates were filtered and washed with PBS to retain cells on the nitrocellulose membrane while allow unbound protein to pass through. The radioactivity on the membrane was measured using a Gamma counter. Non-specific binding was measured by co-incubation with 100+-fold excess of unlabeled AGE. The counts obtained fom the non-specific binding were subtracted from the total binding data to determine specific bidning. The affinity (KD) of AGE binding to U937 cells was calculated to be 11 ug/ml.
The ability of the sRAGE MMBs to reduce AGE binding to U937 cells was determined by a competition assay. Briefly, 125-I-AGE (11 ug/ml) were incubated with sRAGE mimetibodies for 2 hours. The mimetibodies used were diluted two fold from 200 ug/ml to 0.1 ug/ml.
- EXAMPLE 4
SRAGE Mimetibody Reduces AGE-Induced Gene Expression
The mixture of 125-I-AGE and sRAGE mimetibodies was added to U937 and the binding of AGEs to U937 was measured using the binding assay described above. As shown in FIG. 2, sRAGE mimetibodies tested demonstrated reduction of AGE binding to the U937 cells. IC50 of the tested mimetibodies were calculated at approximately 90 nM.
To show AGE stimulation of expression of certain genes, human umbilical endothelial cells (HUVEC) were incubated with 30 ug/ml AGE, 600 ug/ml AGE, for 1, 4, 8 or 12 hours. As a positive control, cells were incubated with 13 ug/ml Lipopolysaccharide (LPS), an inflammatory stimulant. As a negative control, cells were incubated with 600 ug/ml BSA. Cells were harvested and total RNA was isolated using RNeasy (Qiagen, Valencia, Calif.). The RNA was quantitated with the Agilent Bioanalyzer. Quantitative PCR was performed using Assay-on-Demand primers (Applied Biosystems, Foster City, Calif.) for E-Selectin (HS00174057), RAGE (HS00153957), VEGF (HS00173626), IL-6 (HS00174131), GAPDH (HS99999905) and Tissue Factor (HS00175225). The RT-PCR products were quantitated relative to 18s RNA. As shown in FIG. 3, AGE, but not control BSA, increased the mRNA level of each of the genes tested.
To demonstrate the ability of SRAGE mimetibodies to inhibit AGE-stimulated mRNA levels, HUVEC cells were incubated with 3.3 ug/ml sRAGE mimetibody in addition to 600 ug/ml AGE or 13.2 ug/ml sRAGE mimetibody in addition to 600 ug/ml AGE. RNA purification and quantitative PCR were performed as described above. As shown in FIG. 3, sRAGE mimetibodies inhibited the AGE-induction of the transcripts encoding (3A) Tissue Factor, (3B) VEGF, (3C) E-Selectin, (3D) RAGE, and (3E) IL-6.
The present invention now being fully described, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the appended claims.