U.S. patent application number 10/622134 was filed with the patent office on 2005-08-11 for eotaxin : eosinophil chemotactic cytokine.
This patent application is currently assigned to IMPERIAL COLLEGE OF SCIENCE, TECHNOLOGY & MEDICINE. Invention is credited to Griffiths-Johnson, David A., Hsuan, John J., Jose, Peter J., Williams, Timothy J..
Application Number | 20050176931 10/622134 |
Document ID | / |
Family ID | 26303515 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050176931 |
Kind Code |
A1 |
Williams, Timothy J. ; et
al. |
August 11, 2005 |
Eotaxin : eosinophil chemotactic cytokine
Abstract
A chemoattractant protein called "eotaxin" is capable of
attracting eosinophils and of inducing eosinophil accumulation
and/or activation in vitro and in vivo. Various types of agents
that inhibit or otherwise hinder the production, release or
activity of eotaxin may be used therapeutically in the treatment of
asthma and other inflammatory diseases.
Inventors: |
Williams, Timothy J.;
(London, GB) ; Jose, Peter J.; (London, GB)
; Griffiths-Johnson, David A.; (London, GB) ;
Hsuan, John J.; (London, GB) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
IMPERIAL COLLEGE OF SCIENCE,
TECHNOLOGY & MEDICINE
|
Family ID: |
26303515 |
Appl. No.: |
10/622134 |
Filed: |
July 18, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10622134 |
Jul 18, 2003 |
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09291038 |
Apr 14, 1999 |
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6635251 |
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09291038 |
Apr 14, 1999 |
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08615232 |
Aug 13, 1996 |
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5993814 |
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08615232 |
Aug 13, 1996 |
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PCT/GB94/02006 |
Sep 14, 1994 |
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Current U.S.
Class: |
530/350 ;
435/320.1; 435/325; 435/69.1; 536/23.5 |
Current CPC
Class: |
Y10S 514/885 20130101;
A61P 17/00 20180101; G01N 2800/122 20130101; A61P 27/16 20180101;
A61P 37/08 20180101; C07K 14/523 20130101; A61P 29/00 20180101;
G01N 33/6863 20130101; G01N 2333/715 20130101; G01N 2800/24
20130101; A61P 11/00 20180101 |
Class at
Publication: |
530/350 ;
435/069.1; 435/320.1; 435/325; 536/023.5 |
International
Class: |
C07K 014/47; C07H
021/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 14, 1993 |
GB |
9318984.3 |
Apr 29, 1994 |
GB |
9408602.2 |
Sep 14, 1994 |
WO |
PCT/GB94/02006 |
Claims
1. An isolated chemoattractant protein capable of attracting
eosinophils and of inducing eosinophil accumulation and/or
activation in vitro and in vivo consisting of or comprising an
amino acid sequence having at least 40% homology with the amino
acid sequence set out in SEQ ID NO: 1 or SEQ ID NO: 2.
2. A chemoattractant protein as claimed in claim 1, having at least
40% homology with the amino acid sequence set out in SEQ ID NO:
2.
3. A chemcattractant protein as claimed in claim 1, consisting of
or comprising an amino acid sequence as set out in SEQ ID NO: 1, or
SEQ ID NO: 2.
4. A chemoattractant protein capable of attracting eosinophils and
of inducing eosinophil accumulation and/or activation in vitro and
in vivo, which is a polypeptide or peptide fragment of a
chemoattractant protein as claimed in claim 1.
5. A process for the production of a chemoattractant protein as
claimed in claim 1, which comprises obtaining bronchoalveolar
lavage fluid or an inflamatory exudate from a human or a non-human
animal challenged with a provoking stimulus, and isolating a
fraction that demonstrates eosinophil chemcattractant activity in
vitro and in vivo.
6. A process for the production of a chemoattractant protein as
claimed in claim 1, which comprises culturing in vitro macrophages,
lymphocytes, neutrophils, mast cells, airway epithelial cells,
connective tissue cells, vascular endothelial cells or eosinophils
obtained from a human or a non-human animal, and isolating from the
cells or from the cell culture fluid a fraction that demonstrates
eosinophil chemoattractant activity in vitro and in vivo.
7. A chemoattractant protein as claimed in claim 1 obtained by
chemical synthesis or by recombinant DNA technology.
8. An agent that inhibits or otherwise hinders the production,
release or action of a chemoattractant protein as claimed claim 1
the agent being other than RANTES.
9. An agent as claimed in claim 8, which is a receptor for the
chemoattractant protein as claimed in claim 1, an antagonist for
the chemoattractant protein at a receptor for that protein, or an
agent that inhibits the agonist that binds to or activates a
receptor for the chemoattractant protein.
10. An agent as claimed in claim 9, which is a receptor for the
chemoattractant protein.
11. An agent as claimed in claim 9, wherein the receptor antagonist
or the agonist inhibitor is a polypeptide in which the sequence of
the full-length naturally occurring chemoattractant protein has
been modified by amino acid substitution, or is a polypeptide or
peptide fragment comprising part of the amino acid sequence of the
naturally-occurring chemoattractant protein and retaining the
capability of attracting eosinophils and of inducing eosinophil
accumulation and/or activation in vitro and in vivo, or is a
polypeptide or peptide fragment comprising part of the amino acid
sequence of the naturally-occurring chemoattractant protein, which
sequence has been modified by amino acid substitution.
12. An agent as claimed in claim 9, wherein a receptor antagonist
is a chemotactic cytokine that binds to the same receptor as does
the chemoattractant protein.
13. An agent as claimed in claim 8, which is an antibody against
the chemoattractant protein.
14. An agent as claimed in claim 8, for use as a medicament.
15. A method for making a pharmaceutical preparation for treating
asthma or another inflammatory disease comprising admixing an agent
that inhibits or otherwise hinders the production, release or
action of a chemoattractant protein as claimed in claim 1 with a
pharmaceutically acceptable carrier.
16. A pharmaceutical preparation which comprises, as active
ingredient, an agent as claimed in claim 8, in admixture or
conjunction with a pharmaceutically suitable carrier.
17. A method of treating asthma and other inflammatory diseases,
comprising the administration of an effective amount of an agent
that inhibits or otherwise hinders the production, release or
action of a chemoattractant protein as claimed in claim 1.
18. A method of treating asthma and other inflammatory diseases,
comprising the administration of an effective amount of an agent
that inhibits or otherwise hinders the production, release or
action of a chemoattractant protein as claimed in claim 9.
19. An immunoassay for an antigen or other assay for one member of
a specific binding pair, characterised in that the antigen or
member of the specific binding pair is a chemoattractant protein as
claimed in claim 1.
20. An immunoassay for an antibody, characterised in that the
antibody is an antibody that forms a complex with a chemoattractant
protein as claimed in claim 1.
21. A method of testing a compound for an inhibitory effect on the
activity of a chemoattractant cytokine in vitro, characterised in
that the chemcattractant cytokine is a chemoattractant protein as
claimed in claim 1.
22. A method of determining the ability of a substance to induce
eosinophil accumulation and/or activation in vivo, which comprises
administering the substance to a test animal previously treated
with labelled eosinophils and subsequently determining the number
of labelled eosinophils at a skin site.
23. A method for determining the ability of a substance to inhibit
eosinophil accumulation and/or activation induced in vivo by
chemoattractant protein as claimed in claim 1, wherein to an animal
pretreated with labelled eosinophils is administered and the
chemoattractant protein and the number of labelled eosinophils at a
skin site are subsequently determined.
Description
[0001] The present invention relates to a chemotactic cytokine.
[0002] The accumulation of eosinophil leukocytes is a
characteristic feature of IgE-mediated allergic reactions such as
allergic asthma, rhinitis and eczema. Eosinophil accumulation also
occurs in non-allergic asthma. The immediate broncho-constriction
in response to a provoking stimulus in the asthmatic involves mast
cell activation and the release of constrictor mediators. This is
followed after several hours in some individuals by a late
bronchoconstrictor response associated with a massive influx of
eosinophils (1). Repeated provocation results in chronic
inflammation in the airways and a marked hyper-responsiveness to
constrictor mediators. The magnitude of both the late response and
the chronic hyper-responsiveness correlates with the numbers of
eosinophils present in the lung (2,3).
[0003] The present invention provides a chemoattractant protein
capable of attracting eosinophils and of inducing eosinophil
accumulation and/or activation in vitro and in vivo. The
chemoattractant protein of the present invention is designated
"eotaxin".
[0004] Eotaxins are proteins of the C--C branch of the platelet
factor 4 superfamily of chemotactic cytokines. Within the C--C
branch of the platelet factor 4 superfamily of chemotactic
cytokines, or chemokines, certain members have the property of
attracting eosinophils in vitro and some may induce eosinophil
accumulation in vivo. For example, the chemokines RANTES and
MIP-1.alpha. attract eosinophils in vitro while MCP-1 and
MIP-1.beta. do not. ("RANTES" denotes Regulated upon Activation in
Normal T cells Expressed and Secreted, "MIP" denotes Macrophage
Inflammatory Protein, and "MCP" denotes Monocyte Chemoattractant
Protein.)
[0005] Naturally-occurring cytokines within the platelet factor 4
superfamily of chemotactic cytokines may have marked inter- the
amino acid sequence of the protein, and in the carbohydrate
modifications of the protein, while retaining the same
characteristic functional properties. Similar variations in
structure may occur in cytokines obtained from different
individuals within the same species. Many chemokines within the
C--C branch of the platelet factor 4 superfamily show promiscuity
of receptor binding, and the ability of different chemokines to
bind to the same receptor is not necessarily dependent on a high
degree of homology at the amino acid level. Accordingly, both
interspecies and intraspecies variations in protein length, amino
acid sequence and carbohydrate modifications are generally to be
expected for eotaxins.
[0006] The ability to attract eosinophils and to induce eosinophil
accumulation and/or activation in vitro and in vivo is a
characteristic property of eotaxins. Furthermore, eotaxins
generally show substantially no attractive effect for neutrophils
in vivo. The eosinophil chemoattractant effect may be an
inter-species effect, for example, guinea-pig eotaxin appears to be
potent in inducing chemotaxis of human eosinophils in vitro.
[0007] An eotaxin may be obtained from an appropriate body fluid,
for example, from bronchoalveolar lavage fluid obtained from a
human or non-human subject, particularly an allergic subject after
an allergen challenge, either experimentally induced or naturally
incurred. Other sources of eotaxins are, for example, inflammatory
exudate fluids and in vitro cultures of macrophages, lymphocytes,
neutrophils, mast cells, airway epithelial cells, connective tissue
cells, vascular endothelial cells and eosinophils themselves.
[0008] For example, an eotaxin may be obtained from a sensitised
guinea-pig after allergen challenge. Guinea-pig models are useful
as they share many common features with the asthmatic response in
man. Eotaxin obtainable from bronchoalveolar lavage fluid of a
sensitised guinea-pig by sequential HPLC purification generally has
a molecular weight in the range of from 6-16 kDa. (As indicated
above, intraspecies molecular eight variations of this order of
magnitude are observed in members of the platelet factor 4
superfamily.)
[0009] The amino acid sequence of a guinea-pig eotaxin is set out
in SEQ.ID. NO. 1, SEQ.ID. NO. 2 and in FIGS. 7 and 8 of the
accompanying drawings. Other guinea-pig eotaxins will generally
have at least 50% overall homology with the sequence shown in
SEQ.ID. NO. 1 (FIG. 7) at the amino acid level. The homology may be
at least 60%, for example at least 70%, for example at least 80%
with the sequence set out in SEQ.ID. NO. 1 and in FIG. 7.
[0010] Percentage homology in the present case is calculated on the
basis of amino acids that are identical in corresponding positions
in the two sequences under investigation. Conservative
substitutions are not taken into account. In the calculation of
percentage homology of a putative eotaxin molecule under
investigation with the sequence shown in SEQ.ID. NO. 1 (FIG. 7) or
with SEQ.ID. NO. 2 (FIG. 8) if the molecule under investigation has
a different length from the eotaxin set out in SEQ.ID. NO. 1 or
SEQ.ID. NO. 2 (FIG. 7 or FIG. 8), then the calculation is based on
the amino acids in the portion of the molecule under investigation
that overlaps with the sequence shown in SEQ.ID. NO. 1 (FIG. 7) or
SEQ.ID. NO. 2 (FIG. 8). Software packages for the alignment of
amino acid sequences and the calculation of homology are available
commercially, for example, the "Bestfit" program available from
Genetics Computer Group Sequence Analysis Software, Madison, Wis.,
U.S.A.
[0011] Unless specified otherwise, the specific values of
percentage homology between eotaxin and other chemotactic cytokines
given in the present specification have been calculated on the
basis of the eotaxin set out in SEQ.ID. NO. 1 (FIG. 7).
[0012] As indicated above, eotaxins obtainable from species other
than guinea-pigs, for example humans, will exhibit inter-species
differences of the type demonstrated by other members of the C--C
branch of the platelet factor 4 superfamily of chemokines, for
example, differences in protein length, amino acid sequence and
carbohydrate modifications. There may, for example, be variations
in the C- and/or N-terminal residues. For example, it is expected
that the molecular weight of an eotaxin from a species other than
guinea-pig will generally fall within the range of from 6 kDa to 16
kDa, but in some cases an eotaxin may have a molecular weight less
than 6 kDa or more than 16 kDa.
[0013] Similarly, it is expected that in general an eotaxin from a
species other than guinea-pig will have at least 40% overall
homology with the sequence set out in SEQ.ID. NO. 1 and in FIG. 7.
The homology may be at least 50%, for example at least 60%, for
example at least 70%, for example at least 80% with the sequence
set out in SEQ.ID. NO. 1 and in FIG. 7. There may, however, be
eotaxins from species other than guinea-pigs that have less than
40% homology with SEQ.ID. NO. 1 (FIG. 7).
[0014] Eotaxins may be identified by any one or more of the
characteristics set out above, in particular by their ability to
attract and/or active eosinophils in vitro and cause their
accumulation and/or activation in vivo. A characteristic that
assists the identification of a molecule as an eotaxin is the lack
of attractive effect on neutrophils.
[0015] The present invention provides a method of determining the
ability of a substance to induce eosinophil accumulation and/or
activation in vivo, that is to say, a method for testing putative
eotaxins, which comprises administering the substance, generally
intradermally, to a test animal previously treated with labelled,
for example .sup.111In-labelled, eosinophils and subsequently
determining the number of labelled eosinophils at a skin site.
[0016] One in vitro method that may be used to test a putative
eotaxin for the ability to attract and/or activate eosinophils in
vitro is the ability of the substance to increase eosinophil
intracellular calcium levels. Other general methods for determining
chemotactic activity in vitro may be used to test putative eotaxins
in vitro.
[0017] Confirmation that an eosinophil attractant is an eotaxin may
also be made by consideration of sequence homology of that protein
with the sequence set out in SEQ.ID. NO. 1 (FIG. 7) and/or with the
sequence set in SEQ.ID. NO. 2 (FIG. 8) and/or by consideration of
the structural relationship between the protein and the guinea-pig
eotaxin.
[0018] As mentioned above, RANTES and MIP-1.alpha. are both
eosinophil activators. Eotaxin has functional similarities but low
structural homology with RANTES and MIP-1.alpha. (31% homology with
MIP-1.alpha. at the amino acid level calculated on the basis of
SEQ.ID. No. 1 (FIG. 7); 32% homology when calculated on the basis
of the overlapping sequences and 26% homology with RANTES at the
amino acid level calculated on the basis of SEQ.ID. No. 1 (FIG. 7);
27% homology when calculated on the basis of the overlapping
sequences). An eotaxin can be distinguished from RANTES and
MIP-1.alpha. not only by the degree of homology but also by the
overall differences in sequence and structure.
[0019] In addition to full-length eotaxin molecules, the present
invention also provides molecules that comprise less than a full
length eotaxin sequence. Such molecules (called "fragments" herein)
may be polypeptides or peptides. For use as an eotaxin substitute,
a fragment should retain one or more of the biological activities
of the parent molecule.
[0020] Eosinophils contain an armoury of chemicals necessary for
killing parasites. These chemicals have been implicated in the
damage to airway epithelium that occurs in asthma and may relate to
the observed changes in airway function (26,27). From our studies
we suggest that eotaxins should be considered as important
mediators of eosinophil accumulation in vivo. Macrophages,
lymphocytes, neutrophils, mast cells, airway epithelial cells,
connective tissue cells, vascular endothelial cells and eosinophils
themselves are likely candidates as the source of the eosinophil
chemoattractant activity generated in the lung. Platelets may also
have a role as it has been shown that they can release C--C
chemokines (22). Further, an early platelet deposition may be
involved in the subsequent eosinophil accumulation in vivo (28,29)
and there is evidence that platelet-activating factor induces the
synthesis of an unidentified eosinophil chemoattractant in vivo
(30). In this respect, it is of interest that platelet-derived
growth factor can induce gene expression of C--C chemokines in
fibroblasts (31). Furthermore, the C--C chemokines have been
implicated in wound healing (18). This may be important in the
sub-epithelial basement membrane fibrosis that is a prominent
feature of the asthmatic lung. Thus, eotaxins may be involved in
both eosinophil accumulation and in chronic structural changes in
the lung.
[0021] Eotaxins may have an important role in asthma and in other
diseases having an inflammatory component where eosinophil
accumulation and/or activation is a prominent feature, for example,
rhinitis and eczema, especially allergic eczema. Accordingly,
agents that inhibit or otherwise hinder the production, release or
action of eotaxins have potential as selective therapeutic agents.
Such agents and their therapeutic use are part of the present
invention.
[0022] Such agents include inhibitors that affect the interaction
of an eotaxin with eotaxin receptors, for example, by binding to an
eotaxin or to an eotaxin receptor. An example of such an inhibitor
is receptors themselves which, on administration, can bind an
eotaxin and prevent its interaction with naturally-occurring
receptors. Such inhibitory receptors may be soluble or insoluble.
Receptors which are not involved in cell activation may be bound
to, or induced on, cells. Such receptors may also be used to remove
endogenous eotaxin.
[0023] Further examples of agents that affect the interaction of
eotaxins with eotaxin receptors are receptor antagonists, and
antibodies, both antibodies directed against (capable of binding
with) an eotaxin and antibodies directed against an eotaxin
receptor, especially monoclonal antibodies. Any other agent that
inhibits or otherwise hinders the binding of an eotaxin to an
eotaxin receptor also has therapeutic potential, for example, any
other agent that binds to an eotaxin or to an eotaxin receptor.
Further agents that have therapeutic potential are those that
prevent or reduce activation of eotaxin receptors.
[0024] Further agents that inhibit or otherwise hinder the action
of eotaxins are those that change the structure of an eotaxin such
that it is no longer able to bind to an eotaxin receptor, for
example, an enzyme or other agent that degrades eotaxin
specifically.
[0025] Receptor promiscuity is common among chemokines, so although
it is essential that a receptor is capable of binding an eotaxin,
the receptor need not necessarily be eotaxin-specific. For example,
a receptor may bind MIP-1.alpha., RANTES and/or other eosinophil
attractant chemokines as well as an eotaxin.
[0026] As indicated above, possibilities for therapeutic
intervention include the use of a receptor to which an eotaxin
binds, especially a soluble receptor. It may be advantageous to use
an eotaxin-specific receptor. Further possibilities for therapeutic
intervention include receptor antagonists, for example, based on
3-dimensional structures or the amino acid sequences of eotaxins
and/or of eotaxin receptors, and agents found to inhibit eotaxin or
other agonists binding to or activating eotaxin receptors. For
example, a receptor antagonist or an agonist inhibitor may be a
polypeptide in which the sequence of a full-length
naturally-occurring eotaxin has been modified, for example, by
amino acid substitution, or may be a fragment of an eotaxin (that
is to say, a polypeptide or small peptide comprising part of the
amino acid sequence of a naturally-occurring eotaxin), or a
modified fragment of an eotaxin, for example, modified by amino
acid substitution.
[0027] Furthermore, knowledge of the sequence and/or structure of
eotaxins either alone or in combination with knowledge of the
sequence and/or structure of other chemokines that bind to the same
receptor(s) as eotaxins, provides useful information for the design
of therapeutic agents.
[0028] Agents that prevent or inhibit eotaxin synthesis or release
may also be used therapeutically. Such agents and their use are
also part of the present invention.
[0029] All inhibitors of eotaxin activity, synthesis and release,
including soluble receptors, antibodies, antagonists and inhibitors
of agonist binding, and their use are part of the present
invention.
[0030] The present invention accordingly provides an agent that
inhibits or otherwise hinders the production, release or action of
an eotaxin, especially an agent as described above, for use as a
medicament. The invention also provides the use of an agent that
inhibits or otherwise hinders the production, release or action of
an eotaxin, especially an agent as described above, in the
manufacture of a medicament for the treatment of asthma or another
disease having an inflammatory component, particularly with
accumulation of eosinophils, for example, rhinitis or eczema,
especially allergic eczema.
[0031] The use of the structural and sequence information relating
to eotaxins in the design of therapeutically and diagnostically
useful agents, for example, in computer-aided design based on the
three dimensional structure of eotaxins is part of the present
invention.
[0032] Putative inhibitors of eotaxin activity may be screened
using in vivo and in vitro assays based on inhibition of
chemoattraction and/or accumulation and/or activation of
eosinophils by eotaxins. Some general methods for testing the
activity of a compound for an inhibitory effect on the activity of
a chemoattractant cytokine in vitro are known. Such assays may be
used to determine the inhibitory action of a putative inhibitor on
in vitro effects induced in eosinophils by eotaxins.
[0033] Assays that are suitable for screening putative eotaxin
inhibitors include, for example, inhibition in vitro of elevation
of intracellular calcium levels induced in cells by eotaxin. The
method of the present invention for determining the ability of a
substance to induce eosinophil accumulation and/or activation in
vivo, that is to say, a method for testing putative eotaxins, may
also be used to determine the ability of a substance to inhibit
eosinophil accumulation and/or activation induced in vivo by an
eotaxin: an animal is pretreated with labelled eosinophils, an
eotaxin and a putative inhibitor are administered, and the number
of labelled eosinophils at a skin site are determined subsequently.
The eotaxin is generally administered intra-dermally, and the
putative inhibitor may be administered by the same route or by a
different route, for example systemically.
[0034] Examples of in vitro and in vivo assays both for the
determination of eotaxin activity and for the determination of
eotaxin inhibitory activity are described herein. For example,
Example 1 gives a detailed protocol for the in vivo assay of the
present invention, and Example 4 gives detailed protocols of
various assays. The assays described herein may be used as such, or
may be modified as required. Assays may be used alone or in
combination to establish eotaxin and eotaxin-inhibitory activity. A
putative inhibitors may be any of the types of molecules described
above, including receptors, for example, soluble receptors,
antibodies, and antagonists and inhibitors of agonist binding.
Methods for testing putative inhibitors of eotaxins are also part
of the present invention.
[0035] A further aspect of the present invention is a
pharmaceutical preparation comprising, as active ingredient, an
agent that inhibits or otherwise hinders the production, release or
action of an eotaxin, in admixture or in conjunction with a
pharmaceutically suitable carrier. Such agents are described above
and include, for example, an inhibitor of eotaxin synthesis or
release, a soluble eotaxin receptor, an eotaxin receptor antagonist
or an inhibitor of an eotaxin receptor agonist, an antibody against
eotaxin or an antibody against an eotaxin receptor.
[0036] The invention further provides a method of treating asthma
and other inflammatory diseases, comprising the administration of
an effective amount of an agent that inhibits or otherwise hinders
the production, release or action of an eotaxin. The agent may be
as described above, for example, an inhibitor of eotaxin synthesis
or release, a soluble eotaxin receptor, an eotaxin receptor
antagonist or an inhibitor of an eotaxin receptor agonist, or an
antibody against eotaxin or against an eotaxin receptor.
[0037] The present invention also provides assays for eotaxins and
for anti-eotaxin antibodies, especially immunoassays and in
particular ELISAs (enzyme-linked immunosorbent assays). The
invention provides, for example, an immunoassay for an antigen,
characterised in that the antigen is an eotaxin, and also provides
an immunoassay for an antibody, characterised in that the antibody
is an anti-eotaxin antibody. The invention also provides assays for
eotaxins that are analogous to immunoassays for eotaxins but that
use a specific-binding partner other than an antibody. In such
specific-binding partner assays an eotaxin receptor may be used
instead of an anti-eotaxin antibody.
[0038] In an immunoassay, an anti-eotaxin antibody may, for
example, be coated on a solid surface to enable capture and hence
detection of eotaxin. An anti-eotaxin antibody may be used in an
assay for the detection of antibodies to eotaxin, for example, in a
competitive antibody assay. A labelled eotaxin or a derivative
thereof, for example, a recombinant eotaxin or a synthetic peptide
comprising part of the amino acid sequence of an eotaxin may be
used in a competitive antigen assay for eotaxin or may be used to
coat a solid surface in a capture assay for antibodies to eotaxin.
The many different types of assay format are well described in the
literature of the art, see for example "ELISA and Other Solid Phase
Immunoassays, Theoretical and Practical Aspects" Eds. Kemeny D. M.
& Challacombe S. J., John Wiley, 1988. (36). Assays using an
eotaxin receptor instead of an anti-eotaxin antibody may be carried
out analogously.
[0039] The present invention provides a process for the production
of an eotaxin, which comprises obtaining bronchoalveolar lavage
fluid obtained from a human or non-human animal challenged with a
provoking stimulus, for example, from a human suffering from
allergic or non-allergic asthma, or other lung disease, or a
guinea-pig sensitised with a foreign protein, and isolating a
fraction showing eosinophil chemoattractant activity. One method of
isolating an eotaxin-containing fraction of bronchoalveolar lavage
fluid is sequential cation exchange, size exclusion and reversed
phase HPLC systems. The desired fraction generally contains a
polypeptide having a molecular weight in the range from 6-16 kDa.
Purity may be verified by SDS-PAGE. If desired, the authenticity of
the substance obtained may be determined by comparison of the amino
acid sequence thereof with the amino acid sequence set out in
SEQ.ID. NO. 1 or SEQ.ID. NO. 2 (FIG. 7 or FIG. 8).
[0040] Eotaxins may be obtained according to the above procedure
from other sources, for example, from inflammatory exudate fluids,
or from in vitro cultures of macrophages, lymphocytes, neutrophils,
mast cells, airway epithelial cells, connective tissue cells,
vascular endothelial cells and eosinophils themselves.
[0041] Alternatively, a full-length eotaxin, or a part (fragment)
of an eotaxin, for example, a polypeptide or peptide fragment, may
be produced by chemical synthesis, for example, according to the
Merryfield technique. A further method for producing a full-length
eotaxin or a part thereof is by recombinant DNA technology. All
methods of producing eotaxin are part of the present invention.
[0042] To produce a full-length eotaxin polypeptide or a
polypeptide (or peptide) fragment by recombinant DNA technology, a
nucleic acid sequence encoding the polypeptide is inserted into an
expression vector under the control of appropriate control
sequences. A recombinant polypeptide may then be expressed using a
prokaryotic expression system, for example, in E. coli, or using a
eukaryotic cell system, in which case the resulting polypeptide may
be glycosylated. Such techniques are standard see, for example
Sambrook, J., Fritisch, E. F. and Maniatis T., Molecular Cloning A
Laboratory Manual, Cold Spring Harbor Laboratory Press, 1989
(37).
[0043] A nucleic acid encoding all or part of an eotaxin
polypeptide may be obtained by screening a library prepared from
suitable cells, for example, cells from allergen-challenged
guinea-pig or human lung. Screening may be carried out using a
probe comprising sequences characteristic of an eotaxin, in
articular, sequences that distinguish the eotaxin from other
related cytokines, for example, RANTES and MIP-1.alpha.. It may be
preferable to use a long probe, for example, a probe comprising a
nucleic acid sequence encoding a full-length eotaxin
polypeptide.
[0044] Alternatively, the polypeptide sequence of an eotaxin may be
used to design oligonucleotide primers, for example, degenerate
primers. Primers may, for example, comprise bases less specific in
their interaction than the naturally-occurring bases, for example,
inosine may be used. Examples of primers are the sense sequence
[0045] 5' TGC TGT TTC CGI GTI ACI AAC AAA (SEQ.ID.NO. 3)
[0046] based on the amino acid sequence CCFRVTNK, and the
anti-sense sequence
[0047] 5'CAT CTT GTC IGG CTT IAT TTC (SEQ.ID. NO. 4)
[0048] based on the amino acid sequence EIKPDKM. Such primers may
be used for amplification of reverse transcribed mRNA by the
polymerase chain reaction. This provides cDNA probes for screening
libraries, for example, as described above, to isolate full length
eotaxin clones. Primers may include codons chosen on the basis of
known species preference.
[0049] As indicated above, derivatives of naturally occurring
eotaxins are also part of the present invention. Such derivatives
include polypeptides that have one or more of the following
modifications relative to a naturally-occurring eotaxin:
[0050] (i) elongation or shortening at the C-terminus;
[0051] (ii) elongation or shortening at the N-terminus;
[0052] (iii) deletion and/or insertion of internal sequences;
[0053] (iv) amino acid substitutions, for example at the C- and/or
N-terminus; and
[0054] (v) a different pattern of glycosylation. (There is, for
example, a potential O-glycosylation site at residue 70.)
[0055] Such derivatives may function as agonists for
structure/activity relationship studies or as receptor
antagonists.
[0056] Anti-eotaxin antibodies and anti-eotaxin
receptor-antibodies, both polyclonal and monoclonal, may be
produced according to standard techniques, for example, Kohler
& Milstein (38). A full-length eotaxin may be used as antigen,
or it may be preferred to use a fragment of an eotaxin in order to
produce an antibody to a specific antigenic determinant. A
naturally occurring eotaxin may used as antigen. Alternatively, a
recombinant or synthetic eotaxin or eotaxin polypeptide or peptide
may be used.
[0057] FIGS. 1 to 18 of the accompanying drawings illustrate the
present invention. The following is a brief description of the
Figures. A more detailed description of the Figures is given below
and in the Examples section of this specification.
[0058] FIG. 1: Protocol for the generation and assay of eosinophil
chemoattractant activity in vivo.
[0059] FIG. 2: Time course of generation of eosinophil
chemoattractant activity in lungs of sensitized guinea-pigs after
antigen challenge.
[0060] FIGS. 3, 4 and 5 all relate to the purification of eotaxin
from bronchoalveolar lavage (BAL) fluids:
[0061] FIG. 3: Final reversed phase HPLC profile showing absorbance
at 214 nm and the acetonitrile gradient.
[0062] FIG. 4: Measurement of .sup.111In-eosinophil chemoattractant
activity of the fractions obtained on HPLC chromatography.
[0063] FIG. 5: Measurement of .sup.111In-neutrophil chemoattractant
activity; lack of significant activity observed.
[0064] FIG. 6: SDS-PAGE analysis of C18 reversed phase HPLC
fractions 50-56.
[0065] FIGS. 7 and 8: Amino acid sequences of an isolated
guinea-pig eotaxin.
[0066] FIG. 9: Comparison of the eotaxin sequence of FIG. 7 with
human MCP-1, MCP-2, MCP-3 (21), guinea-pig MCP-1 (24), human
MIP-1.alpha., MIP-1.beta. and RANTES (18) showing conserved
residues (shaded).
[0067] FIG. 10: Comparison of .sup.111In-eosinophil accumulation in
vivo using guinea-pig eotaxin and the recombinant human proteins
RANTES, MIP-1.alpha. and MCP-1.
[0068] FIG. 11 (Inset): Inhibition of the binding of
.sup.125I-RANTES to guinea-pig eosinophils in vitro induced by
eotaxin and RANTES but not by a member of the C--X--C branch of
chemokines, IL-8.
[0069] FIGS. 12, 13 and 14 illustrate the potential of blocking the
response to guinea-pig eotaxin. This makes use of the fact that
human RANTES, whilst competing with eotaxin for binding sites, does
not activate guinea-pig eosinophils.
[0070] FIG. 12: Elevation of intracellular calcium levels in human
eosinophils in vitro induced by eotaxin, RANTES and, at high
concentration only, MCP-1.
[0071] FIG. 13: Elevation of intracellular calcium levels in
guinea-pig eosinophils in vitro induced by eotaxin, but not human
RANTES and MCP-1.
[0072] FIG. 14: Representative traces showing inhibition of
guinea-pig eotaxin-induced elevation of intracellular calcium
levels in guinea-pig eosinophils in vitro by the previous exposure
of the same cells to human RANTES. Inset:
[0073] FIG. 15: Values (mean.+-.SEM) for four separate eosinophil
preparations.
[0074] FIG. 16: Dose response curve showing inhibition of
guinea-pig eotaxin-induced elevation of intracellular calcium
levels in guinea-pig eosinophils in vitro by the previous exposure
of the same cells to human RANTES.
[0075] FIG. 17: Histogram showing comparison of in vivo response of
guinea-pig eosinophils to eotaxin, RANTES and RANTES plus eotaxin
co-injected intradermally.
[0076] FIG. 18: Histogram showing number of eosinophils and
neutrophils in bronchoalveolar lavage fluid (BAL) after
administration of guinea-pig eotaxin as an aerosol to guinea-pig
airways.
[0077] As in allergic asthmatic patients, exposure of sensitised
guinea-pigs to aerosolised antigen results in an immediate phase of
bronchoconstriction with associated mast cell degranulation
followed, in some individuals, by a late phase of
bronchoconstriction and airway hyper-responsiveness (4-7). Although
clearly no one model mimics all the features of the human disease,
the guinea-pig model shares common features with the asthmatic
response in man and has been extensively used to investigate
possible mechanisms (7). In particular, in both guinea-pig and man,
the immediate response to allergen triggers the subsequent
accumulation in the lung of high numbers of eosinophils.
Experiments were designed to detect the appearance in the lung of
chemoattractants that may be responsible for the accumulation of
eosinophils. A strategy was employed that has previously been
applied to the identification of neutrophil chemoattractants in
inflammatory exudates (8-10).
[0078] Guinea-pigs were sensitised with intraperitoneal ovalbumin
on day 1 followed by a short exposure of their lungs to aerosolised
ovalbumin at day 8. On day 15-21 animals were challenged with
aerosolised ovalbumin and killed at different intervals using a
barbiturate overdose. Immediately after death the airways were
lavaged with saline. The broncho-alveolar lavage (BAL) fluid was
centrifuged to remove cells, and supernatants were either stored at
-20.degree. C. for assay or subjected to purification. Eosinophil
chemoattractant activity in BAL fluid samples or HPLC fractions was
tested by injecting them intradermally into assay guinea-pigs
previously given intravenous injections of .sup.111In-eosinophils
(11,12). After a 2 or 4 h interval, assay animals were killed and
the punched out skin sites were counted in a gamma-counter (FIG.
1).
[0079] FIG. 2 shows the time-course of appearance of eosinophil
chemoattractant activity in BAL fluid. Significant activity was
observed 30 min after antigen challenge. Activity increased up to 3
h, remained high at 6 h, but was not significant in 24 h samples.
Control samples (BAL fluid from sham-sensitised/challenged or
sensitised/sham-challenged guinea-pigs) taken at 3 h had no
significant activity.
[0080] Eosinophil chemoattractant activity, which we termed
eotaxin, was purified from 3 h BAL fluid by sequential cation
exchange, size exclusion and reversed phase HPLC using the in vivo
.sup.111In-eosinophil accumulation assay to measure the activity of
fractions throughout. Eotaxin eluted as a single discreet peak of
bioactivity from both the cation exchange and the size exclusion
steps, indicating a strongly cationic protein of 7-14 kDa. Reversed
phase chromatography separated eosinophil chemoattractant activity
into two peaks (fractions 51+52 and fraction 54), which were
associated with discreet peaks of protein absorbance (FIGS. 3 and
4). Selectivity for eosinophils was shown by the lack of
significant neutrophil chemoattractant activity in these fractions
as measured by the accumulation of .sup.111n-neutrophils in the
skin assay (FIG. 5). Histological examination of skin injected with
eotaxin (2 pmol) demonstrated eosinophil accumulation at 4 and 24
h, particularly around small blood vessels (haematoxylin and eosin
stains).
[0081] SDS-PAGE analysis revealed a single protein band in each of
fractions 51, 52 and 54 (FIG. 6). The protein in fractions 51 and
52 was slightly larger than that in fraction 54. This was confirmed
by mass analysis in which the major signals were at approximately
8.81 and 8.38 kDa respectively (see Example 3). N-terminal
sequencing of fractions 51, 52 and 54 revealed identical amino acid
sequences (see FIG. 7). The N-terminal 37 residue sequence of
eotaxin as set out in SEQ.ID. NO. 1 and FIG. 7 shows 57% homology
with human monocyte chemotactic protein (MCP-1 (13), otherwise
known as MCAF (14) and JE (15)). Tryptic peptides of fraction 54
were also sequenced and readily aligned by comparison with human
MCP-1 to give the virtually complete sequence of eotaxin with an
overall homology of 53%, see FIG. 7. It is likely that the
variations in molecular mass reflect differential glycosylation as
the four mass signals obtained (two major and two minor, see
Example 3) are all different from each other by multiples of
approximately 220 mass units. The sequence contains no
N-glycosylation sites, but a potential O-glycosylation site at
position 70 has been identified (see Example 3). Human MCP-1 also
exhibits heterogeneity on SDS-PAGE due to differences in the
O-linked carbohydrate modification (16).
[0082] The platelet factor 4 superfamily of chemotactic cytokines,
or chemokines, is characterised by four conserved cysteines. The
relative position of the two N-terminal cysteines allows the
subdivision of this superfamily into the C--X--C chemokines (eg.
IL-8 (17)) which are predominantly neutrophil chemoattractants and
the C--C chemokines (eg. MCP-1, RANTES, MIP-1.alpha. and
MIP-1.beta. (18)) which are chemotactic for leukocytes other than
neutrophils. Eotaxin is a member of the C--C branch of chemokines.
The greatest homology (53%) is with human MCP-1 which, in the
limited in vitro studies to date, has been reported to be inactive
on human eosinophils (19,20) and with the recently described human
MCP-2 (54%) and MCP-3 (51% homology calculated on the basis of
SEQ.ID. No. 1 (FIG. 7); 54% homology when calculated on the basis
of the overlapping sequences) (21). Homology with other human C--C
chemokines (FIG. 9) is: MIP-1.beta. (37% calculated on the basis of
SEQ.ID. No. 1 (FIG. 7); 39% when calculated on the basis of the
overlapping sequences), MIP-1.alpha. (31% calculated on the basis
of SEQ.ID. No. 1 (FIG. 7); 32% when calculated on the basis of the
overlapping sequences) and RANTES (26% calculated on the basis of
SEQ.ID. No. 1 (FIG. 7); 27% when calculated on the basis of the
overlapping sequences). The latter two proteins have recently been
shown to be potent eosinophil activators in vitro (20,22) whereas
MIP-1.beta. activates lymphocytes in vitro (23) but apparently not
eosinophils (20). Eotaxin shows the greatest structural homology
with human MCP-1, MCP-2 and MCP-3. Eotaxin has functional
similarities, but relatively low homology, when compared with
RANTES and MIP-1.alpha.. Eotaxin is clearly a distinct molecule
from guinea-pig MCP-1; the latter has recently been cloned (24) and
it has only a 43% homology with the eotaxin sequence, see FIG. 9.
Guinea-pig MCP-1 was shown to be chemotactic for monocytes but was
not tested on eosinophils (24). Interestingly, eotaxin has a 41%
homology with a C--C protein whose gene is expressed in mouse mast
cells and upregulated 2 h after the interaction between IgE and
antigen (25). No functional activity has been reported for this
protein but it is distinct (51% homology) from mouse MCP-1/JE
(25).
[0083] Guinea-pig eotaxin was very potent in inducing eosinophil
accumulation in vivo: 1-2 pmol/skin site giving a 730.+-.140%
response (mean.+-.s.e.m., n=18 animals) compared with
saline-injected sites. Further, marked eosinophil accumulation was
seen within 30 minutes of intradermal injection (FIG. 10). This is
supported by experiments in vitro. The effect of eotaxin on
eosinophils in vitro was shown by (i) inhibition of binding of
.sup.125I-RANTES to guinea-pig cells (FIG. 11), (ii) elevation of
cytoplasmic calcium in human and guinea-pig cells (FIGS. 12 and 13)
and (iii) chemotaxis of human eosinophils in a Boyden chamber
system: the chemotactic responses to eotaxin and RANTES were of
similar magnitude over the range 0.1-3.0 nM. In contrast to
eotaxin, human recombinant MCP-1 and RANTES did not induce
guinea-pig eosinophil responses in vivo or in vitro (FIGS. 10 and
13). This may reflect a species difference although RANTES did bind
to guinea-pig eosinophils without inducing activation (FIG. 11,
inset in FIG. 10). Eotaxin has a similar potency to RANTES on human
eosinophils whereas MCP-1 is either inactive (20) or active only at
high doses (FIG. 12). Thus, eotaxin has a potent direct effect on
both human and guinea-pig eosinophils.
[0084] Responses of guinea-pig eosinophils to guinea-pig eotaxin in
vitro and in vivo can be inhibited by human RANTES. FIGS. 14, 15
and 16 show the response of FURA-2-loaded guinea-pig eosinophils to
guinea-pig eotaxin before and after the addition of human RANTES.
The eotaxin-induced increase in intracellular calcium concentration
is reduced to a substantial degree when the cells are first exposed
to human RANTES, which itself fails to induce a response. FIG. 17
shows that human RANTES, when coinjected with the eotaxin, reduces
the accumulation of guinea-pig eosinophils induced by eotaxin in
guinea-pig skin in vivo. The results support our observations that
eotaxin exhibits competitive binding with radiolabelled human
RANTES on guinea-pig eosinophils and that eotaxin is a potent
functional stimulant whereas RANTES is not. Accordingly, RANTES
appears to act as a receptor antagonist for eotaxin on guinea-pig
eosinophils.
[0085] FIG. 18 shows that eosinophils accumulate in guinea-pig
airways in vivo within 24 hours of the administration of
aerosolized guinea-pig eotaxin, whereas substantially no
accumulation of neutrophils is observed.
[0086] The following Examples illustrate the present invention.
EXAMPLE 1
[0087] Production and Testing of Bronchoalveolar Lavage Fluid
[0088] METHODS: Male Dunkin Hartley guinea-pigs (300-400 g) were
sensitised with intraperitoneal ovalbumin (OA, 1 mg) on day 1
followed by exposure to aerosolised antigen (2% OA for 5 min using
an ultrasonic nebuliser) on day 8 (6). On day 15-21, animals were
pretreated with an antihistamine to prevent acute fatality
(pyrilamine, 10 mg kg.sup.-1, i.p.) and challenged by exposure to
aerosolised antigen (1% OA for 20 min). At different times after
antigen challenge animals were treated with atropine (0.06 mg
kg.sup.-1, i.p.) to prevent broncho-constriction and killed with a
barbiturate overdose. Broncho-alveolar lavage was performed with 4
ml saline. Samples were centrifuged to remove cells and the
supernatant stored at -20.degree. C. prior to assay. BAL samples
were assayed by intradermal injection (0.1 ml) into guinea-pigs
previously given intravenous injections of 5.times.10.sup.6
111In-eosinophils (elicited in donor animals by repeated
intraperitoneal injections of horse serum and purified on
discontinuous Percoll gradients, >94% purity) (11,12). After 4
hours, assay animals were killed and the skin sites punched out for
gamma-counting. Data are presented as the mean.+-.s.e.m. and were
tested by one way analysis of variance. A p value of <0.05 was
considered statistically significant.
[0089] RESULTS: FIG. 1 shows, schematically, procedures for the
generation and measurement of eosinophil chemoattractant activity
in vivo. FIG. 2 illustrates the time course of generation of
eosinophil chemoattractant activity in lungs of sensitised
guinea-pigs after antigen challenge (filled squares, n=4-10).
Activity was measured in an in vivo skin assay of
.sup.111In-eosinophil accumulation in unsensitised guinea-pigs (3
test animals per BAL sample). Significant activity was seen in
bronchoalveolar lavage samples taken 0.5, 1.5, 3 and 6 h after
antigen challenge (compared to responses to intradermal saline,
shown as the dotted line). No significant activity was observed in
24 h samples. No activity was seen in lavage samples obtained 3 h
after sham (saline) challenge of sensitised animals (filled
circles, n=5) or antigen challenge of sham (saline) sensitised
animals (filled diamonds, n=5).
EXAMPLE 2
[0090] Purification of Eotaxin from Bronchoalveolar Lavage
Fluids
[0091] METHODS: Bronchoalveolar lavage (BAL) fluid collected from
25 sensitised guinea-pigs (each lavaged with 4 ml, followed by
2.times.10 ml, saline) 3 h after antigen challenge (1% OA, 5 min
exposure) was applied to a cation exchange HPLC column (Ultropac
TSK535CM, 7.5.times.150 mm). Activity was eluted at approx 1.4 M
ammonium acetate, pH5.5, and lyophilised for size exclusion HPLC
(Ultropac TSK columns SWP, 7.5.times.75 mm, G4000SW, 7.5.times.600
mm, and G2000SW, 7.5.times.600 mm, in series, equilibrated in 0.08%
TFA). Activity eluted at approx 7-14 kDa. This was applied to a
wide pore (300 A) Vydac C18 reversed phase HPLC column (4.times.250
mm) in 0.08% TFA, eluted with a linear gradient of acetonitrile
(0-80% ACN in 0.08% TFA, over 80 mins, at 1 ml min.sup.-1) and 0.5
min fractions were collected. Aliquots (4%) of each fraction were
lyophilised in the presence of carrier protein (BSA, <0.1 ng
endotoxin mg.sup.-1) and redissolved in 0.8 ml saline for testing
in the skin bioassays of .sup.111In-eosinophil and
.sup.111n-neutrophil accumulation over 2 hours (n=4). Eosinophils
(99%, 0.5% neutrophils) were elicited with repeated
intra-peritoneal injections of horse serum (11,12) and neutrophils
(99.4%, 0.6% eosinophils) were elicited with a single
intraperitoneal injection of casein (5% w/v, 15 ml) 17 h prior to
purification on discontinuous Percoll gradients and labelling with
.sup.111In.
[0092] RESULTS: The results are presented in FIGS. 3, 4 and 5. FIG.
3 shows the final reversed phase HPLC profile showing absorbance at
214 nm and the acetonitrile gradient. FIG. 4 shows that eosinophil
chemoattractant activity was seen in 2 peaks, corresponding to
fractions 51+52 and fraction 54, which corresponded to discreet
peaks of absorbance. FIG. 5 shows that no significant neutrophil
chemoattractant activity was detected in these fractions. In
contrast, guinea-pig C5a des Arg (30% zymosan-activated plasma
(11), approx 10 pmol/site) induced the accumulation of both
.sup.111In-eosinophils (5211.+-.893) and .sup.111In-neutrophils
(9872.+-.473). Fractions 50, 53, 55 and 56 consistently gave little
or no activity in the guinea-pig skin bioassays of leukocyte
accumulation. No significant protein absorbance was detected in the
remainder of the gradient (up to 80% acetonitrile).
EXAMPLE 3
[0093] Purity, Mass Analysis and Protein Sequence of Eotaxin
[0094] METHODS: 2% aliquots of each fraction were lyophilised,
redissolved in 10 .mu.l SDS buffer, heated (95.degree. C., 5 min)
and 0.3 .mu.l run on 8-25% gradient gels in a Pharmacia Phast
System. Gels were visualised with silver staining. Mass analysis
was performed on fractions 51, 52 and 54 using a Finnigan MAT
Lasermat with .alpha.-cyano-4-hydroxycynnamic acid and sinapinic
acid matrices. Mass measurements were calibrated internally using
protein standards. 5% aliquots of each bioactive fraction (51, 52
and 54) were applied directly to automated N-terminal sequence
analysis using fast cycles on an Applied Biosystems 477A containing
a microcartridge essentially as described (32). The amino-terminal
37, 35 and 29 residues were obtained for fractions 51, 52 and 54
respectively. No differences between corresponding positions were
found. The apparent initial yields of these three analyses were all
approximately 7-8 pmol. Thus fractions 51, 52 and 54 contained
approx 200 pmol each, assuming 70-80% sequencing yields. Gaps were
found at positions 8,9 and 33, consistent with the presence of
cysteine residues at these positions. Approximately 30 pmol of
fraction 54 was reduced and alkylated by sequential treatment with
1 mM dithiothreitol for 5 min at 50.degree. C. and then 10 mM
acrylamide for 30 min at 37.degree. C. before digestion with
alkylated trypsin (Promega) in 20 mM Tris/HCl, pH8.8, containing
0.5% Thesit. Peptides were separated using a Reliasil C18 (300
.ANG., 5 .mu.m) column (1.times.150 mm) developed with a linear
acetonitrile concentration gradient in 0.08% tri-fluoroacetic acid
at 50 .mu.l/min on a Microm HPLC system. Purified peptides were
subjected to N-terminal sequence analysis as above, but all four
cysteine residues were positively identified as the
PTH-cys-S-.beta.-propionamide derivative (33). Position 70 gave no
PTH derivative in peptides T6 and T7 and is a probable position of
O-glycosylation.
[0095] RESULTS: The results are presented in FIGS. 6, 7, 8 and 9.
FIG. 6 is a photograph of the SDS-PAGE gel. For reference, human
IL-8 (72 amino acids, approx 8 kDa) was run in lanes A, B and C
(12, 2.4 and 0.5 ng/0.3 .mu.l/lane respectively). Laser desorption
time of flight mass analysis gave signals at 8.81 kDa (major) and
9.03 kDa (minor) for each of fractions 51 and 52. Fraction 54 gave
signals at 8.38 kDa (major) and 8.15 kDa (minor).
[0096] FIG. 7 and SEQ.ID. NO. 1 show the amino acid sequence of
eotaxin, which was determined by sequencing the intact molecule as
well as peptides derived from digestion with trypsin (T).
N-terminal analyses showed the highest homology with human MCP-1
(57%) and the tryptic peptides were readily aligned by comparison
with the human MCP-1 sequence. FIG. 8 shows the amino acids
sequence as confirmed by nucleic acid sequencing. FIG. 9 is a
comparison of the eotaxin sequence with human MCP-1, MCP-2, MCP-3
(21), guinea-pig MCP-1 (24), human MIP-1.alpha., MIP-1.beta. and
RANTES (18) showing conserved residues (shaded).
EXAMPLE 4
[0097] In Vitro and In Vivo Testing of Eotaxin
[0098] Methods:
[0099] (i) Eotaxin was a pool of both peaks of bioactivity
(fractions 51+52 and fraction 54) from the final reversed phase
HPLC separation described in Example 2 (see FIGS. 3, 4 and 5).
.sup.111In-eosinophil accumulation in guinea-pig skin was measured
over 4 h as described in Example 1 (see FIGS. 1 and 2). In the same
animals (n=4) additional sites were injected with eotaxin 30
minutes before killing.
[0100] (ii) For the binding studies, 4.times.10.sup.5 eosinophils
were incubated with 0.1 nM .sup.125I-RANTES and various
concentrations of cold ligand (50 .mu.l at 0.degree. C. for 2 h).
The Hank's buffered salt solution contained 30 mM HEPES, 10 mM
EDTA, 0.1% sodium azide and 1% BSA at pH7.5. Results are the mean
of two assays each done in triplicate.
[0101] (iii) For measurement of intracellular calcium levels human
and guinea-pig eosinophils (10.sup.7 cells/ml in
Ca.sup.2+/Mg.sup.2+-free PBS+0.1% BSA) were loaded with
fura-2-acetoxymethyl ester (2.5 .mu.M, 30 min at 37.degree. C.).
After two washes cells were resuspended at 10.sup.6 cells/ml in
Ca.sup.2+/Mg.sup.2+-free PBS containing 10 mM HEPES, 0.25% BSA and
10 mM glucose (pH7.4). Aliquots were dispensed into quartz cuvettes
and the external [Ca.sup.2+] adjusted to 1 mM with CaCl.sub.2.
Changes in fluorescence were monitored at 37.degree. C. using a
Perkin Elmer LS50 spectrophotometer at excitation wavelengths 340
nm and 380 nm and emission wavelength 510 nm. [Ca.sup.2+].sub.i
levels were calculated as described previously (34) using the ratio
of the two fluorescence readings and a Kd for Ca.sup.2+ binding at
37.degree. C. of 224 nM. Peripheral human eosinophils were prepared
as described previously (35) by density centrifugation on Percoll
followed by immunomagnetic removal of CD16.sup.+ neutrophils using
the MACS system. Guinea-pig eosinophils were prepared as described
in Example 1 (11,12).
[0102] (iv) To test for suppression of eosinophil accumulation in
vivo using human RANTES, accumulation of .sup.111-labelled
guinea-pig eosinophils in skin sites was measured as described
above. Guinea-pigs were injected with 1.8 pmol eotaxin (n=2), 100
pmol RANTES (n=1) or both 1.8 pmol eotaxin and 100 pmol RANTES
(n=2). Intradermal saline was used as control.
[0103] (v) For testing of receptor antagonist activity, the
fura-2-acetoxymethyl ester-loaded guinea-pig eosinophils were
stimulated with 3 nM eotaxin with or without pretreatment with
human RANTES.
[0104] (vi) To investigate the effect of aerosol exposure of
guinea-pigs to eotaxin, naive guinea-pigs were exposed to an
aerosol of either eotaxin or a control medium (n=8 per group).
Exposure was performed by placing two animals in a single chamber
and nebulising 24 pmol of eotaxin dissolved in 10 ml PBS containing
BSA carrier protein at 80 .mu.g/ml over a period of 35-40 minutes.
Control animals received aerosolised PBS/BSA in the same manner.
The animals were killed 20 hours after exposure to eotaxin or
control medium. BAL fluid (5.times.10 ml HBSS, 10 mM EDTA, pH 7.35)
was recovered and centrifuged (300 g, 20 min, 4.degree. C.). Total
BAL cell count was determined by haemo-cytometer and differential
cell counts performed on stained (DiffQuick) cytospin preparations
(3 per animal, 400 cell counts per slide).
[0105] RESULTS: The results are presented in FIGS. 10, 11, 12, 13,
14, 15, 16, 17 and 18.
[0106] FIG. 10 shows that guinea-pig eotaxin (1.6 pmol) induces
significant .sup.111In-eosinophil accumulation in vivo 30 min (open
squares, p<0.01) and 4 h (filled squares, p<0.01) after
intradermal injection. In contrast, the recombinant human proteins,
RANTES, MIP-1.alpha. and MCP-1, at doses up to 100 pmol, were
without effect over 4 hours. FIG. 11 inset shows that eotaxin and
RANTES, but not the C--X--C chemokine IL-8, inhibit the binding of
.sup.125I-RANTES (B.sub.0=14.4%) to guinea-pig eosinophils in
vitro. FIG. 17 shows (a) that human RANTES does not induce
significant eosinophil accumulation and (b) that human RANTES
inhibits to a substantial degree the eosinophil accumulation
induced by eotaxin, which suggests that RANTES acts as a receptor
antagonist for eotaxin in vivo.
[0107] FIG. 12 shows that eotaxin, RANTES and, at high
concentration only, MCP-1 induce elevation of intracellular calcium
levels in human eosinophils in vitro. Traces are with eosinophils
from one donor. In two other donors 2 nM eotaxin gave a mean
calcium elevation of 61 nM. In the three donors 97.3.+-.1.2%
eosinophils) responses to 10 RANTES were 194.+-.74 nM
[Ca.sup.2+].sub.i and responses to 100 nM MCP-1 were 93.+-.38 nM
[Ca.sup.2+].sub.i. FIG. 13 shows that guinea-pig eotaxin, but not
human RANTES or MCP-1, elevates intracellular calcium levels in
guinea-pig eosinophils in vitro. Traces are with cells from one
donor. In three donors (97.5.+-.0.8% eosinophils) responses were: 2
nM eotaxin, 90.+-.13 nM [Ca.sup.2+].sub.i; 100 nM RANTES,
2.0.+-.1.7 nM [Ca.sup.2+].sub.i; 100 nM MCP-1, 3.3.+-.0.7 nM
[Ca.sup.2+].sub.i.
[0108] FIG. 14 and the inset FIG. 15 show that prior treatment of
guinea-pig eosinophils with RANTES (100 nM) inhibits the increase
in intracellular free calcium levels seen when eosinophils are
treated with eotaxin (3nM) alone. RANTES appears to be acting as a
receptor antagonist in guinea-pig eosinophils. FIG. 16 is a
dose-response curve using 3 nM eotaxin and increasing amounts of
RANTES.
[0109] FIG. 18 shows that guinea-pig eotaxin, administered as an
aerosol, induces eosinophil accumulation in guinea-pig airways in
vivo, whereas substantially no accumulation of neutrophils is
observed.
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Sequence CWU 1
1
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