MCP-1, MCP-2, MCP-3, MCP-4, and MCP-5

16 Pages·0.289 MB·English

by  Rollins B.J.

MCP-1, MCP-2, MCP-3,
MCP-4, and MCP-5
Barrett J. Rollins
Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street,
Boston, MA 02115, USA
*corresponding author tel: [phone], fax: [phone], e-mail: [email protected]
DOI: 10.1006/rwcy.2000.11001.
SUMMARY 1988), and a screen for IFN(cid:13)-inducible genes in
human peripheral blood lymphocytes identified HC-
14,whichencodesMCP-2(Changetal.,1989).When
Monocyte chemoattractant proteins (MCPs) are
murine JE cDNA was used to probe a human
closely related members of the CC chemokine family.
fibroblast cDNA library at relatively high stringency,
All are chemoattractants for monocytes, activated T
the only clone isolated was human MCP-1 (Rollins
cells, and NK cells, and some MCPs also attract
et al., 1989). While the function of JE was unknown
eosinophils. Their expression patterns suggest that
at the time of its cloning, its protein product was
thesechemokinesmayplayimportantrolesinhuman
shown to be secreted and, based on sequence homo-
diseases that are characterized by mononuclear or
logies, it was predicted to be a cytokine.
eosinophilic cell infiltration. In vivo analyses with
Soon after the cloning of JE and FIC, several
neutralizing antibodies and genetically targeted mice
groups purified monocyte-specific chemoattractant
indicate that MCP-1 in particular is a major mono-
proteins based on their in vitro chemotaxis activities.
cyte chemoattractant, and its activity is necessary for
The first to be isolated was a protein secreted from
the full pathophysiological manifestations of diseases
baboon aortic smooth muscle cells which was, in
such as atherosclerosis. Targeting the MCPs or their
retrospect,ahomologofhumanMCP-1(Valenteetal.,
receptors is likely to have significant therapeutic
1988). Human MCP-1 itself was purified indepen-
potential.
dentlybytwogroupsthefollowingyear(Matsushima
et al., 1989; Yoshimura et al., 1989), and they were
the first to provide sequence data identifying MCP-1
BACKGROUND
as the product of human JE (Furutani et al., 1989;
Robinsonet al.,1989).Similarly,MCP-2andMCP-3
Discovery
werepurifiedfromtheconditionedmediumofIL-1(cid:12)-
stimulated human osteosarcoma cells on the basis of
MCPs were discovered in three ways, all of which their ability to attract monocytes in vitro (Van
havebeencharacteristicofchemokinegenediscovery. Damme et al., 1992).
These were differential screening, purification of Large-scale sequencing projects (Uguccioni et al.,
protein-mediated activities, and genomics-based 1996) and homology cloning exploiting the related-
homology searches. Differential screening identified ness of MCPs to eotaxin (Garcia-Zepeda et al., 1996)
murine MCP-1 in 1983 as the product of the JE gene resulted in the cloning of human MCP-4. PCR
in an experiment designed to clone genes whose primers with degenerate sequences based on con-
expression is induced by PDGF in fibroblasts served chemokine motifs were used to isolate novel
(Cochran et al., 1983; Rollins et al., 1988). A similar cDNAs from allergic murine lung tissue and resulted
screen a few years later resulted in the isolation of in the cloning of MCP-5 (Jia et al., 1996). Another
FIC,themurinehomologofMCP-3(Almendraletal., group screened a mouse genomic DNA library with
1146 Barrett J. Rollins
human MCP-4 and independently identified murine CD45RO(cid:135)), and NK cells, and induce histamine
MCP-5 (for which no clear-cut human ortholog has releasefrombasophils.MCP-2,-3,and-4alsobindto
yet emerged) (Sarafi et al., 1997). CCR3, making them potent eosinophil chemoattrac-
tants in vitro. As expected, therefore, these proteins
are expressed in a variety of pathophysiological con-
Alternative names
ditions characterized by mononuclear or eosinophilic
infiltrates.
See Table 1.
Structure GENE AND GENE REGULATION
All MCPs share the secondary and tertiary structural Accession numbers
features characteristic of chemokines. Under condi-
tions required for crystal and NMR structural ana- See Table 2.
lyses, all are dimers. The implications of higher order
structure for receptor activation are discussed below.
Chromosome location
Main activities and
All thehuman MCPsmap to17q11.2and their genes
pathophysiological roles
are found in the following order: (cen) – I-309 –
(MCP-4,MCP-2)–eotaxin–MCP-1–MCP-3–(tel).
SinceallMCPsbindtoCCR2withhighaffinity,they All murine MCPs map to chromosome 11. Only
all attract monocytes, memory T lymphocytes (i.e. MCP-1 has been mapped with precision at 46.50cM.
Table 1 Alternative names
‘MCP’ name Gene name Nomenclature namea Alternative names
MCP-1 SCYA2 CCL2 MCAF, JE, SMC-CF, HC-11
MCP-2 SCYA8 CCL8 HC-14
MCP-3 SCYA7 CCL7 FIC, MARC, NC28
MCP-4 SCYA13 CCL13 CK(cid:12)10, NCC-1
MCP-5 ScyA12 ?CCL12b
aNomenclatureproposedatthe1999KeystoneConferenceonChemokinesandChemokineReceptors.
bMurinenomenclaturehasnotyetbeendetermined,butaputativehumanorthologofMCP-5would
bedesignatedCCL12.
Table 2 Gene accession numbers
MCP Human Mouse Rat Rabbit
MCP-1 M28226 (mRNA) M19681 (gene) AF058786 (mRNA) M57440 (mRNA)
M28223, 4, 5 (gene)
MCP-2 Y10802 (mRNA)
X99886 (gene)
MCP-3 X72308 (mRNA) S71251 (mRNA)
X72309 (gene)
MCP-4 U46767(mRNA)
AJ000979 (gene)
MCP-5 U50712 (mRNA)
MCP-1, MCP-2, MCP-3, MCP-4, and MCP-5 1147
Relevant linkages isnotablefortheabsoluterequirementofa7bpmotif
in the proximal 30 UTR in order for PDGF-inducible
expression to occur (Freter et al., 1992). Additional
The MCPs map to the telomeric end of the CC
regulatory domains are listed in Table 5.
chemokine cluster. Human MCP-4’s nearest mapped
centromeric neighbor is I-309. However, other CC
chemokines that have not yetbeen mapped with high Cells and tissues that express
resolution may intervene. Eotaxin maps within the
the gene
MCP cluster.
Regulatory sites and corresponding See section on Cellular sources and tissue expression.
transcription factors
PROTEIN
Several regulatory sites governing human MCP-1
transcription have been mapped (Ueda et al., 1994,
Accession numbers
1997) as shown in Table 3.
Limited mapping of transcriptional control sites
See Table 6.
has also been reported for MCP-3, See Table 4.
Murine MCP-1 has been investigated both by
mutational analysis of promoter/reporter construct
Sequence
expression in response to PDGF stimulation (Freter
et al., 1992, 1995, 1996) and in vivo genomic
See Figure 1.
footprinting in response to TNF(cid:11) stimulation (Ping
etal.,1996).RegulationofmurineMCP-1expression
Table 4 Transcriptional control of human MCP-3
Table 3 Transcriptional control of human MCP-1
Positiona Transcription factor/
Positiona Transcription factor
Transcriptional effect
(cid:255)2704 to (cid:255)2667 ?
(cid:255)190 to (cid:255)172 ?; Ets-like domain; transcriptional
(cid:255)2635 to (cid:255)2626 NF(cid:20)B ((p65) and c-Rel/p65) repression
2
(cid:255)2604 to (cid:255)2595 NF(cid:20)B ((p65) and c-Rel/p65) (cid:255)172 to (cid:255)100 ?; positive regulatory domain
2
(cid:255)61 to (cid:255)51 SP-1 (cid:255)37 SP-1
aRelativetotranscriptionalinitiationsite(Rollinsetal.,1989). aRelativetotranscriptionalinitiationsite.
Table 5 Transcriptional control of murine MCP-1
Positiona Domain designation Transcription factor
(cid:255)2538 to (cid:255)2298 ‘Enhancer region’
(cid:255)2548 to(cid:255)2522 Element I/kB-x NF(cid:20)B
(cid:255)2504 to (cid:255)2478 Element II 30kDa protein; ? Ser/Thr phosphorylated
(cid:255)2467 to (cid:255)2440 Element III ?
(cid:255)2377 to (cid:255)2356 Element IV/(cid:20)B-1 90kDa Ser/Thr phosphoprotein; NF(cid:20)B ((p65) )
2
(cid:255)2352 to (cid:255)2342 (cid:20)B-2 NF(cid:20)B
(cid:255)145 to (cid:255)154 (cid:20)B-3 ? (not NF(cid:20)B)
(cid:255)56 to (cid:255)43 AP-1/GC box SP-1
? C/EBP-related protein 2 (Bretz)
aRelativetotranscriptionalinitiationsite(Rollinsetal.,1988).
1148 Barrett J. Rollins
Table 6 Protein accession numbers
MCP Human Mouse Rat Rabbit
MCP-1 126842; SwissProt 126844; SwissProt 126846; SwissProt 126845; SwissProt
P13500 P10148 P14844 P28292
MCP-2 2506280 SwissProt
P80075
MCP-3 313708; EMBL: 417192; SwissProt
CAA51055.1 Q03366
MCP-4 2689217; EMBL:
X98306
MCP-5 1477582; GenBank
AAB50053.1
Figure1 ProteinsequencesofhumanandmurineMCPs.Aminoacidssharedbyall
memberswithinaspeciesarehighlightedinred.However,notetheconservedamino
acidchangesatmostnonidenticalpositions.(Fullcolourfigurecanbeviewedonline.)
Table7 MolecularweightsandisoelectricpointsofMCPs
Description of protein
MCP Molecular weight of pI
mature protein (Daltons)
All MCPs have similarly low molecular weights
Human MCP-1 8684 9.3
except for murine MCP-1, which is significantly
Human MCP-2 8913 9.3
larger due to its C-terminal extension (Table 7). All
are also highly basic proteins. Human MCP-3 8955 9.7
Human MCP-4 8598 9.9
Discussion of crystal structure Murine MCP-1 12,847 9.8
Murine MCP-3 8511 9.5
The structure of MCP-1 has been solved by Murine MCP-5 9333 9.1
NMR (Handel and Domaille, 1996) and X-ray
MCP-1, MCP-2, MCP-3, MCP-4, and MCP-5 1149
Figure 2 Left, MCP-1 monomer showing N- and C-terminal ends; disulfide bonds are in yellow. Right,
MCP-1dimershowingthemajorinterfaceoccurringatnew(cid:12)sheetsneartheN-terminiofthemonomers.
Structures created by RasMol using coordinates of Handel and Domaille (Handel and Domaille, 1996).
(Full colour figure can be viewed online.)
crystallography(Lubkowskietal.,1997).TheMCP-1 The structure of MCP-3 has also been solved by
monomerhasthetypicalchemokinefoldinwhichthe NMR (Meunier et al., 1997), and the monomer has
N-terminal cysteines are followed by a long loop that the same typical chemokine fold. It is also dimeric in
leads into three antiparallel (cid:12)-pleated sheets in a solution, but forms only the CXC-like dimer.
Greekkey motif(Figure2).Theproteinterminates in
an (cid:11) helix that overlies the three (cid:12) sheets. In the
Important homologies
NMR analysis, the N-terminus of MCP-1 is highly
disordered, but in the crystal structure, amino acids
2–6 form a well-ordered 3 helix. Considering the high degree of similarity among all
10
Both structural analyses find MCP-1 in dimeric members of the chemokine family, it is not a simple
form. In the solution structure, the dimer interface task to make unique cross-species assignments of
occursalongtheedgeofaninduced(cid:12) sheetinvolving orthologs. In particular, the identification of murine
aminoacids9–11toformthedimericstructuretypical MCP-1 (the product of the JE gene) as the ortholog
ofCCchemokines(Figure2).Whilethisdimerisalso of human MCP-1 appears to present problems
found in the crystals, additional oligomers are because of a 49 amino acid C-terminal extension in
present, including tetramers and an alternative dimer the murine protein that is not found in the human
that is similar to the CXC dimers in which the inter- protein (see above). Furthermore, the existence of
face occurs along the edge of the first long (cid:12) sheet. murine MCP-5 confounds matters because it is also
Monomer affinities for each other appear to be similar to human MCP-1 and lacks the C-terminal
quite low, suggesting that at physiologically effective domain thatdistinguishesmurine MCP-1. Because of
concentrations, MCP-1 should predominantly be in the absence of the C-terminal domain from MCP-5,
its monomer form (Paolini et al., 1994). In addition, overall homology measurements suggest that MCP-5
nondimerizing variants of MCP-1 retain full in vitro may be more closely related to human MCP-1 than
activity (Paavola et al., 1998). Nonetheless, since murine MCP-1.
there are biochemical data indicating that MCP-1 However, several observations argue that MCP-5
may activate its receptor as a dimer (Zhang and is not the ortholog of human MCP-1. First, high
Rollins, 1995), the question of whether MCP-1 stringency Southern analysis of human genomic
monomers or dimers interact with the receptor DNA using murine MCP-1 as a probe identifies
remains unresolved. only human MCP-1 fragments (Rollins et al., 1989);
1150 Barrett J. Rollins
Figure 3 Top, dendrogram indicating relatedness description of MCP-1 purification, the glycosylated
ofaminoacidsencodedbyexons1and2ofhuman form had been designated MCP-1(cid:11) and the non-
MCP-1, murine MCP-1, and MCP-5. Bottom, glycosylated form MCP-1(cid:12) (Yoshimura et al., 1989).
percent similarity and percent divergence among Theglycosylatedformhasbeenreportedtobe2-to3-
the same domains of these proteins. (Comparisons
fold less potent than nonglycosylated MCP-1 in
generated using the Jotun-Hein method with a
monocyte chemotaxis assays in vitro (Proost et al.,
residue weight table using 2.5 accepted mutations
1998). N-Terminally truncated forms of natural
per residue.)
MCP-1 produced by PBMCs have been described
that are missing the first four and first five amino
acids (Proost et al., 1998). As expected from struc-
ture/activity analyses, these variants have no intrinsic
chemoattractant activity but rather act as inhibitors.
Another variant lacking the last seven amino acids
retains full activity.
Murine MCP-1 is extensively glycosylated; nearly
50% of its apparent molecular weight of 30–35kDa
is due to carbohydrate. Its C-terminal extension
(see Figure 1) is rich in serines and threonines, and
enzymatic analysis indicates that the microhetero-
geneity observed on SDS-PAGE analysis of murine
MCP-1 is due to a variable number of terminal sialic
acids added to a constant number of O-linked oligo-
saccharides per peptide chain (Ernst et al., 1994).
MCP-5 hybridizes to a different set of fragments (Jia
Glycosylation has no effect on in vitro monocyte
et al., 1996). Second, murine MCP-1 is a higher
chemoattractant activity.
affinity ligand for CCR2 than MCP-5 (Sarafi et al.,
MCP-2 is not glycosylated, but naturally truncated
1997). Third, expression patterns of murine MCP-1
formsproducedbyPBMCshavebeenisolated(Proost
are closer to those of human MCP-1 (Tesch et al.,
et al., 1998). A variant lacking the first five amino
1999).
acidshasnochemoattractantactivitybutinhibitsthat
Thus despite MCP-5’s apparently higher degree of
ofMCP-1,MCP-2,MCP-3,andRANTES.Avariant
similarity to human MCP-1, murine MCP-1 appears
lacking the last two amino acids has full activity.
tobethebetterfunctionalortholog.Thisparadoxcan
Human MCP-3 is N-glycosylated (Minty et al.,
be resolved by considering chemokine structure/
1993).
activity relationship studies which implicate amino
acids encoded by exons 1 and 2 as the major activity
and specificity domains (Clark-Lewis et al., 1991;
CELLULAR SOURCES AND
Hebert et al., 1991; Zhang and Rollins, 1995). When
these regions are considered, murine MCP-1 is more TISSUE EXPRESSION
closely relatedtohumanMCP-1 thanmurine MCP-5
(Figure 3). In fact, extension of these similarities into Cellular sources that produce
the50 UTRmayalsoexplainsimilaritiesinexpression
patterns. Therefore, while cross-species assignments
The MCPs fall into the category of ‘inflammatory’
ofchemokineorthologsmustbemadewithcaution,it
chemokines, i.e. those whose expression is highly
appears that the protein traditionally known as
inducible. In some circumstances, especially those
murine MCP-1 is still the best model for examining
involvingMCP-2andMCP-4,constitutiveexpression
questions about human MCP-1 in the mouse.
canbeobserved,butinawidevarietyoftissues,MCP
expression is ordinarily silent and is induced by a
Posttranslational modifications
plethora of stimuli. Very recent data indicate that a
subset of cells in the splenic periarteriolar lymphatic
Although a canonical N-glycosylation sequence is sheath and in the medulla of lymph nodes constitu-
present in MCP-1, there is no detectable N-linked tivelyexpressMCP-1andmayinfluenceTlymphocyte
sugar. Rather, a small amount of sialylated O-linked trafficking (Gu et al., 2000). Expression patterns are
carbohydrate(Jiangetal.,1990)isprobablyaddedto listedinTable8.Forprimaryreferences,thereaderis
serines or threonines near the C-terminus of the referred to the reviews of Rollins (1997) and
protein (Zhang et al., 1994). In the original Baggiolini (1998).
MCP-1, MCP-2, MCP-3, MCP-4, and MCP-5 1151
Table 8 MCP expression
MCP Cell type/Organ Inducer
MCP-1
Fibroblasts PDGF/IL-1/TNF(cid:11)/viruses/dsRNA/LPS/cholera toxin
Endothelial cells IL-1/TNF/IFN(cid:13)/IL-4/MM-LDL/stretch
Vascular smooth muscle cells PDGF/MM-LDL/stretch
Monocytes/macrophages (including cell lines, LPS/IFN(cid:13)/PMA
HL60, U937, THP1)
Neutrophils TNF
Keratinocytes IFN(cid:13)
Synovial cells IL-1
Type II pneumocyte cell line IL-1/TNF
Mesangial cells IL-1/TNF/IFN(cid:13)/basic FGF/LIF/IL-6
Retinal pigmented epithelial cells IL-1/TNF/LPS
Malignant cell lines (glioma,
sarcoma, melanoma, hepatoma)
Luteal cells
Secondary lymphoid organs
Lung (epithelium, alveolar macrophages) Asthma and granuloma models
Brain (astrocytes) Experimental allergic encephalomyelitis
models/seizure
Spinal cord Contusion injury
Seminal vesicles
Kidney Inflammation (e.g. glomerulonephritis)/
hypoxia/Transplant rejection
Arterial plaques Atherosclerosis
Plasma Sepsis
Heart transplant rejection
MCP-2
Fibroblasts IL-1/IFN(cid:13)/dsRNA/measles virus
Neutrophils
Osteosarcoma cell line IL-1/IFN(cid:13)
Astrocytes EAE/multiple sclerosis
Organs: small intestine, peripheral blood,
heart, placenta, lung, skeletal muscle,
ovary, colon, spinal cord, pancreas, and thymus
Porcine luteal cells
MCP-3
Fibroblasts PDGF
Monocytes TNF/IL-1/IFN(cid:13)/LPS/lipoarabinomannan
Platelets
Bronchial epithelium Asthma models
Kidney glomerulonephritis
Astrocytes EAE/multiple sclerosis
Skin Atopy
1152 Barrett J. Rollins
Table 8 (Continued)
MCP Cell type/Organ Inducer
MCP-4
Endothelial cells IL-1/TNF
Dermal fibroblasts
Bronchoalveolar lavage cells Asthma
Bronchial epithelial cell lines (A549, BEAS-2B) IL-1/TNF/IFN(cid:13)
PBMC PHA/IL-2
Nasal epithelium Sinusitis
Arterial plaques (endothelial cells/macrophages) Atherosclerosis
Organs: small intestine, thymus, colon, heart, placenta
MCP-5
Macrophage cell line (RAW 264.7) IFN(cid:13)/LPS
Lung (alveolar macrophages/smooth muscle cells) Asthma models
Spinal cord Spinal cord contusion injury
Lymph node stromal cells
Thymic stromal cells
Table 9 MCP receptor specificities
Eliciting and inhibitory stimuli,
including exogenous and
MCP Receptor (K <5nM)
d
endogenous modulators
hMCP-1 hCCR2, mCCR2
hMCP-2 CCR2, CCR3, CCR5
Glucocorticoids(Poonetal.,1991),estrogen(Frazier-
Jessen and Kovacs, 1995), and progesterone (Kelley hMCP-3 CCR1, CCR2, CCR3, D6
et al., 1997) inhibit MCP-1 expression, and gluco- hMCP-4 CCR2, CCR3, D6
corticoidscanalsosuppressexpressionofMCP-3and
mMCP-1 CCR2, mCCR2, mD6
MCP-4 (Smith and Herschman, 1995; Stellato et al.,
mMCP-3 mCCR2
1997). Expression of MCP-1 in monocytes and
macrophagesisinhibitedbyTGF(cid:12) (Kitamura,1997). mMCP-5 mCCR2, hCCR2
MCP-1andMCP-3 expressioncanbedownregulated
in many cell types by the generally suppressive cyto-
kines IL-4, IL-13, and IL-10 (Kucharzik et al., 1998),
MCPs also bind to CCR2 with high affinity, but
although IL-4 induces MCP-1 expression in endothe-
unlike MCP-1, they interact with other chemokine
lial cells (Rollins and Pober, 1991).
receptors as well. Their interactions are summarized
Although heparin and other glycosaminoglycans
in Table 9.
have been shown to modulate the activities of other
chemokines,suchaneffecthasnotyetbeendescribed
IN VITRO ACTIVITIES
for the MCPs.
In vitro findings
RECEPTOR UTILIZATION
In vitro activities of MCP-1 are summarized in
BothhumanandmurineMCP-1arehighlyspecificin Table 10. Target cell specificities for the MCPs are
their receptor usage, binding only to human or predicted by their receptor-binding specificities. For
murine CCR2 with high affinity (K <1nM). Both example,throughtheiractivationofCCR2,allMCPs
d
ligands will also bind to the promiscuous chemokine are chemoattractants for monocytes, activated mem-
receptor D6, but with a K of (cid:25)16nM. All the other ory (CD45RO(cid:135)) T lymphocytes, and NK cells.
d
MCP-1, MCP-2, MCP-3, MCP-4, and MCP-5 1153
Table 10 In vitro activities of MCPs
MCP Target cell Activities
MCP-1
Monocytes Chemotaxis; calcium flux; respiratory burst;
enzyme release; increased expression of
CD11b, CD11c, CD18; transient adhesion
of VLA-4 to VCAM-1 or 40kDa fibronectin;
prolonged adhesion of VLA-5 to 120kDa
fibronectin; increased IL-1 and
IL-6 secretion; in vitro tumor cytostatic
activity; increased in vitro tumor
cytocidal activity (macrophages)
in presence of LPS
T lymphocytes (CD45RO(cid:135)) Chemotaxis; calcium flux; enhanced
proliferative response to CD3 ligation
or B7-1 costimulation; Th2 polarization
NK cells Chemotaxis; calcium flux; enzyme release
Basophils Histamine release; chemotaxis
Dendritic cells (CD34(cid:135)-derived) Chemotaxis
Hematopoietic progenitors Suppression of proliferation
MCP-2
Monocytes Chemotaxis; calcium flux; enzyme release
(<MCP-1)
T lymphocytes (CD45RO(cid:135)) Chemotaxis
T lymphocytes (CD45RA(cid:135)) Chemotaxis
NK cells Chemotaxis; enzyme release
Eosinophils Chemotaxis
Basophils Histamine release
Dendritic cells (CD34(cid:135)-derived) Chemotaxis
Dendritic cells (monocyte-derived) Chemotaxis
MCP-3
Monocytes Chemotaxis; calcium flux; enzyme release
(<MCP-1)
T lymphocytes (CD45RO(cid:135)) Chemotaxis, increased adhesion to ICAM-1
NK cells Chemotaxis; enzyme release
Eosinophils Chemotaxis; calcium flux; respiratory burst;
cytoskeletal rearrangement; transient
adhesion of VLA-4 to VCAM-1 or
40kDa fibronectin, firm CD11b/CD18
adhesion to ICAM-1
Basophils Histamine release; chemotaxis
Dendritic cells (CD34(cid:135)-derived) Chemotaxis
Dendritic cells (monocyte-derived) Chemotaxis
MCP-4
Monocytes Chemotaxis; calcium flux
T lymphocytes (CD45RO(cid:135)) Chemotaxis
Eosinophils Chemotaxis; calcium flux; respiratory burst;
cytoskeletal rearrangement
Basophils Histamine release, chemotaxis
1154 Barrett J. Rollins
Table 10 (Continued)
MCP Target cell Activities
Dendritic cells (CD34(cid:135)-derived) Chemotaxis
Dendritic cells (monocyte-derived) Chemotaxis
MCP-5
Monocytes Chemotaxis; calcium flux
T lymphocytes Chemotaxis
B lymphocytes Chemotaxis
Eosinophils Chemotaxis
Resting T cells express extremely low levels of CCR2 been reported to attract immature monocyte-derived
and are not targets for these chemokines. MCP-2 is dendritic cells in vitro (Sozzani et al., 1995), while all
the only member of this group that can also attract the human MCPs appear to attract CD34(cid:135) cell-
CD45RA(cid:135)Tcells(Rothetal.,1995).Inaddition,the derived dendritic cells (Xu et al., 1996). MCP-1 also
MCPs induce histamine release from basophils; suppresses the proliferation of hematopoietic pro-
MCP-1’s effect is exerted through CCR2, but the genitor cells (Broxmeyer et al., 1993).
others activate CCR3. Additional effects on target Because MCP-2, -3, and -4 activate CCR3, these
cells include a transient increase in intracellular cal- chemokines also have effects on eosinophils and
cium concentration and, in monocytes, the respira- basophils. (The interaction of MCP-3 with CCR1
tory burst. MCP-1 is a more potent inducer of may also be relevant in this regard, but antibody
N-acetyl-(cid:12)-D-glucuronidase release from monocytes blocking studies suggest that MCP-3 exerts its effects
than MCP-2 or MCP-3 (Uguccioni et al., 1995). on eosinophils through CCR3 only (Heath et al.,
MCP-1 enhances the proliferative response of 1997).) For example, all these chemokines attract
naı¨ve T cells to anti-CD3 and to B7-1-induced eosinophils, while MCP-3 and -4 also attract
costimulation (Taub et al., 1996), and has been basophils. In addition, MCP-3 and MCP-4 have
reported to polarize naı¨ve T cells toward TH2 been shown to induce a calcium flux, formation of
responses when challenged by antigen (Karpus et al., reactive oxygen species, and actin polymerization in
1997). Consistent with its proposed role in monocyte eosinophils. MCP-3 induces transient VLA-4-
emigration from the vasculature, MCP-1 upregulates mediated binding of eosinophils to VCAM-1 or
expressionofCD11b,CD11c,andCD18(Jiangetal., fibronectin followed by sustained upregulation of
1992; Vaddi and Newton, 1994). Furthermore, in CD11b/CD18 binding to ICAM.
flow chambers, MCP-1 causes transient activation
of VLA-4-mediated adhesion to VCAM-1 or to the
Regulatory molecules: Inhibitors
40kDa fragment of fibronectin, followed by pro-
longed firm adhesion of VLA-5 to the 120kDa and enhancers
fragment of fibronectin (Weber et al., 1996a). In
contrast, MCP-1 has no such effects on T lympho- Truncation of the N-terminal domain of MCP-1 re-
cytes (Campbell et al., 1998). Similarly, MCP-1 does sultsin theformationof apotent inhibitorofMCP-1
not induce rapid adhesion of T cells to ICAM-1 in activity both in vitro (Zhang and Rollins, 1995) and
flowchambers,butMCP-3does.MCP-3alsoinduces in vivo (Gong et al., 1997). N-Terminally truncated
the transient binding of eosinophils to VCAM-1 or MCP-2 acts as an inhibitor of MCP-1, MCP-3, and
fibronectin via VLA-4, followed by firm (cid:12) integrin RANTES (Proost et al., 1998).
2
adhesion (Weber et al., 1996b).
MCP-1 stimulates expression of IL-1 and IL-6 in
Bioassays used
monocytes and enhances their cytostatic activity
against tumor cell lines in vitro (Matsushima et al.,
1989; Jiang et al., 1992). It stimulates cytocidal acti- Chemoattractant activities are monitored by in vitro
vity of syngeneic elicited macrophages against tumor chemotaxis assays. Other relevant assays include
cells when addedin the presence ofLPS (Singh et al., intracellular calcium concentration measurements,
1993). MCP-2, -3, and -4 (but not MCP-1) have reactive oxygen intermediate formation, histamine