Human complement C3 derivates with cobra venom factor-like function

Abstract

A modified human complement C3 protein (C3) is disclosed comprising a substitution of a portion of a human C3 protein, with a corresponding portion of a Cobra Venom Factor protein (CVF) which results in a human C3 protein with CVF functions, but with substantially reduced immunogenicity. Advantageously, the C3 protein can be manipulated to contain at least one of the following CVF functions: increased stability of the C3 convertase and increased resistance to the actions of factors H and / or I. A large number of hybrid C3 proteins containing substitutions in the C-terminal portion of the alpha chain of C3 are presented and tested for the above functions. Methods of treatment of diseases such as reperfusion injury, autoimmune diseases, and other diseases of increased complement activation are presented as well as methods of increasing the effectiveness of gene therapeutics and other therapeutics.

Description

RELATED APPLICATIONS

[0001] This International application claims priority to U.S. Provisional Applications 60 / 567,069, filed Apr. 30, 2004, 60 / 653,247, filed Feb. 14, 2005, and 60 / 667,352, filed Mar. 30, 2005, each of which is incorporated by reference in its entirety.FIELD OF THE INVENTION

[0002] The invention relates generally to chimeric derivatives of Human Complement C3 having a substitution of a portion of a human C3 protein with a corresponding portion of a Cobra Venom Factor (CVF) protein. Preferably, a portion of the alpha chain of C3 is substituted with the corresponding portion of CVF.BACKGROUND OF THE INVENTION

[0003] The third component of complement, C3, plays a pivotal role in both the classical and alternative pathways of complement activation, and many of the physiologic C3 activation products have important functions in the immune response and host defense. In the alternative pathway, the activated form of C3, C3b, is a structural subunit of the C3 convertase. This bimo...

Examples

example 1

Production of Human Complement C3 / CVF Hybrid Proteins

[0076]The replacement of human C3 sequences with CVF sequences representing important structural features for CVF specific functions allows the creation of C3 derivatives with CVF-like functions. Thus, embodiments of the invention are directed to generation of human C3 derivatives that exhibit the CVF-specific function of depleting complement by forming a stable convertase for use as a novel therapeutic agent to deplete complement in clinical situations where complement activation is part of the pathogenesis. Because the structural changes in human C3 caused by CVF-specific sequences are minimal, it is clear that the modified C3 molecules can exhibit significantly reduced or event absent immunogenicity.

[0077]The human C3 molecules in Table 1 are engineered to contain specific CVF sequences so as to create human C3 derivatives with CVF functions. Some embodiments of the invention provide smaller substitutions in these areas, to def...

example 2

Expression of Modified human C3 Proteins

[0087]The proteins were produced in the Drosophila S2 cell system, using the Drosophila Bip signal sequence for secretion of the proteins. Briefly, the plasmids pMB / HC3-1550, pMB / HC3-1504, pMB / HC3-1496, pMB / HC3-1550 / 1617, and pMB / HC3-1348 were transfected into Drosophila S2 cells using the calcium phosphate method of Chen and Okayama (Chen, C., and Okayama, H. (1987) Mol. Cell. Biol. 7(8), 2745-2752, herein incorporated by reference in its entirety). S2 cells were transfected with a mixture of expression plasmid and pCoBlast, using a ratio of 19:1 (w:w). Following transfection, cells containing both plasmids were selected using blasticidin (25 μg / ml). For expression, 1-liter cultures of transfected cells were grown in serum-free medium (Hi-Five plus L-glutamine), in the absence of blasticidin. When the cells reached a density of 5×106 cells / ml., production of the recombinant proteins was induced by the addition of CuSO4 to a final concentratio...

example 3

Results of the Activity Measurements of the Modified Human Complement C3 Proteins

[0090]The purified modified human C3 protein hybrids were subjected to a number of functional analyses as follows.

[0091]Complement Depletion:

[0092]This assay measures the ability of a protein to deplete complement in human (or other) serum. The assay was done in two steps. In the first step, the protein of interest was diluted to the desired concentrations in buffer, usually by serial dilution (typically from less than a nanogram / microliter up to approximately 320 ng / microliter or 3.2 μg in the 10 microliters used in the assay). Then, a 10 μl aliquot of the diluted protein was mixed with undiluted serum. The mixture was incubated at 37° C. for 3 hours, which allows the protein to activate complement by forming a C3 convertase. The convertases formed were then able to activate C3 in the serum. Then, to measure the amount of complement activity left, the serum was diluted and mixed with antibody-sensitize...

RELATED APPLICATIONS

[0001] This International application claims priority to U.S. Provisional Applications 60 / 567,069, filed Apr. 30, 2004, 60 / 653,247, filed Feb. 14, 2005, and 60 / 667,352, filed Mar. 30, 2005, each of which is incorporated by reference in its entirety.FIELD OF THE INVENTION

[0002] The invention relates generally to chimeric derivatives of Human Complement C3 having a substitution of a portion of a human C3 protein with a corresponding portion of a Cobra Venom Factor (CVF) protein. Preferably, a portion of the alpha chain of C3 is substituted with the corresponding portion of CVF.BACKGROUND OF THE INVENTION

[0003] The third component of complement, C3, plays a pivotal role in both the classical and alternative pathways of complement activation, and many of the physiologic C3 activation products have important functions in the immune response and host defense. In the alternative pathway, the activated form of C3, C3b, is a structural subunit of the C3 convertase. This bimo...

Examples

example 1

Production of Human Complement C3 / CVF Hybrid Proteins

[0076]The replacement of human C3 sequences with CVF sequences representing important structural features for CVF specific functions allows the creation of C3 derivatives with CVF-like functions. Thus, embodiments of the invention are directed to generation of human C3 derivatives that exhibit the CVF-specific function of depleting complement by forming a stable convertase for use as a novel therapeutic agent to deplete complement in clinical situations where complement activation is part of the pathogenesis. Because the structural changes in human C3 caused by CVF-specific sequences are minimal, it is clear that the modified C3 molecules can exhibit significantly reduced or event absent immunogenicity.

[0077]The human C3 molecules in Table 1 are engineered to contain specific CVF sequences so as to create human C3 derivatives with CVF functions. Some embodiments of the invention provide smaller substitutions in these areas, to def...

example 2

Expression of Modified human C3 Proteins

[0087]The proteins were produced in the Drosophila S2 cell system, using the Drosophila Bip signal sequence for secretion of the proteins. Briefly, the plasmids pMB / HC3-1550, pMB / HC3-1504, pMB / HC3-1496, pMB / HC3-1550 / 1617, and pMB / HC3-1348 were transfected into Drosophila S2 cells using the calcium phosphate method of Chen and Okayama (Chen, C., and Okayama, H. (1987) Mol. Cell. Biol. 7(8), 2745-2752, herein incorporated by reference in its entirety). S2 cells were transfected with a mixture of expression plasmid and pCoBlast, using a ratio of 19:1 (w:w). Following transfection, cells containing both plasmids were selected using blasticidin (25 μg / ml). For expression, 1-liter cultures of transfected cells were grown in serum-free medium (Hi-Five plus L-glutamine), in the absence of blasticidin. When the cells reached a density of 5×106 cells / ml., production of the recombinant proteins was induced by the addition of CuSO4 to a final concentratio...

example 3

Results of the Activity Measurements of the Modified Human Complement C3 Proteins

[0090]The purified modified human C3 protein hybrids were subjected to a number of functional analyses as follows.

[0091]Complement Depletion:

[0092]This assay measures the ability of a protein to deplete complement in human (or other) serum. The assay was done in two steps. In the first step, the protein of interest was diluted to the desired concentrations in buffer, usually by serial dilution (typically from less than a nanogram / microliter up to approximately 320 ng / microliter or 3.2 μg in the 10 microliters used in the assay). Then, a 10 μl aliquot of the diluted protein was mixed with undiluted serum. The mixture was incubated at 37° C. for 3 hours, which allows the protein to activate complement by forming a C3 convertase. The convertases formed were then able to activate C3 in the serum. Then, to measure the amount of complement activity left, the serum was diluted and mixed with antibody-sensitize...

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