Recombinant Fc-IL-18BPc isoform inhibits IL-18-induced cytokine production.
ABSTRACT IL-18 is a pro-inflammatory cytokine that is produced from T cells and NK cells. IL-18 has been implicated in the pathogenesis of various inflammatory and cardiovascular diseases. IL-18 binding protein (IL-18BP) is a natural inhibitor of IL-18 that possesses higher affinity to IL-18 than that of the IL-18 receptor alpha chain on the cell surface. Human isoform a and c among four isoforms of IL-18BPs have an inhibitory effect on IL-18-induced cytokines whereas mouse IL-18BP isoforms exist only in two isoforms: c and d. Fc-fusion protein is a molecule in which the immunoglobulin Fc is fused genetically to a protein of interest, such as an extracellular domain of a receptor, ligand, or enzyme. In this study, we expressed and purified human Fc-IL-18BPa and c isoforms from CHO-DG44 cells and their biological activities were compared to each other. This is the first time that expressed recombinant human Fc-IL-18BPc has been examined for its biological activity on IL-18-induced IFNγ in human PBMC and IL-6 in A549/IL-18Rβ.
- SourceAvailable from: Daniela Novick[Show abstract] [Hide abstract]
ABSTRACT: The IL-18 binding protein (IL-18BP) is a circulating inhibitor of the proinflammatory cytokine IL-18. It is constitutively expressed in mononuclear cells, and elevated expression is induced by IFN-gamma. In this study, we characterized the IL-18BP promoter. We first showed that induction is at the transcriptional level and requires de novo protein synthesis. The IL-18BP promoter resides within 1.6 kb DNA upstream of the first exon and includes at least six regulatory elements. We identified in the basal promoter a gamma-activated sequence (GAS) proximal to the transcription start site (base 1), followed by an IFN regulatory factor 1 response element (IRF-E) and two CCAATenhancer binding protein beta (CEBPbeta) sites, all of which are essential for basal promoter activity. Furthermore, GAS and IRF-E were essential for IFN-gamma-induced transcription. Indeed, sera of IRF-1-deficient mice lacked basal and IFN-gamma-induced IL-18BP. We found that after induction of IRF-1 by IFN-gamma, it formed a complex with CEBPbeta, which bound to the IRF-E and GAS-containing proximal DNA. In contrast, the IFN-gamma-induced signal transducer and activator of transcription 1 dimer did not associate with this GAS. In addition, we identified a silencer element and a distal enhancer at bases -1081 to -1272, which was also physically associated with IRF-1. The IRF-1-CEBPbeta complex described here probably plays a fundamental role in regulating additional IFN-gamma-responsive genes.Proceedings of the National Academy of Sciences 01/2003; 99(26):16957-62. · 9.81 Impact Factor
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ABSTRACT: Experimental autoimmune encephalomyelitis (EAE) is a model of autoimmune central nervous system (CNS) disease that is mediated by autoreactive Th1 cells secreting the proinflammatory cytokine interferon (IFN)-gamma. Interleukin (IL)-12 in its heterodimeric p35/p40 isoform and the recently described cytokine IL-18 potently induce T cell production of IFN-gamma. Interleukin-1beta converting enzyme (ICE) is required to convert IL-18 precursor protein into its biologically active mature form. In this study, we used semiquantitative reverse transciptase-polymerase chain reaction to determine steady state levels of IL-12, IL-18, and ICE mRNA in the spinal cord of Lewis rats at different stages of EAE. In control rats, we found significant IL-18, ICE, and IL-12p35, but not IL-12p40 mRNA expression. IL-18 mRNA increased during the acute stage of EAE together with a marked induction of ICE mRNA. IL-12p35 mRNA levels did not change significantly throughout the course of EAE. Surprisingly, the peak expression of IL-12p40 mRNA was delayed by several days relative to the peak of T cell infiltration and IFN-gamma mRNA synthesis. Our data implicate the IL-18/ICE pathway in the amplification of Th1-mediated immune responses in the CNS but suggest a different, so far undefined role of endogenous IL-12 in the late effector phase of EAE.Journal of Neuroimmunology 12/1998; 91(1-2):93-9. · 3.03 Impact Factor
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ABSTRACT: New treatment options for chronic hepatitis C (CHC) that offer improved efficacy, tolerability, and convenience compared with weekly interferon alfa (IFNalpha)-based regimens are needed. Longer-acting IFNalpha formulations with reduced dosing requirements and improved tolerability have been a focus of drug development efforts. The objective of this report is to review the characteristics, pharmacokinetics, pharmacodynamics, and clinical and virologic outcomes reported in studies of albinterferon alfa-2b (alb-IFN), a novel fusion protein of human albumin and human IFNalpha-2b. This review was based on all published data regarding alb-IFN to date. An unlimited PubMed database search was conducted using the keywords 'albuferon,' 'albinterferon,' and 'albumin AND interferon.' Albinterferon alfa-2b has been developed for the treatment of CHC. This agent exhibits a prolonged half-life and duration of antiviral activity that indicate potential suitability for dosing intervals of 2-4 weeks. Phase 2 trials in prior IFN nonresponders and IFN-naïve patients with genotype 1 or 2/3 CHC have shown antiviral activity and acceptable safety/tolerability of alb-IFN 900-1500 microg every 2 weeks and 1200-1500 microg every 4 weeks. Based on the phase 2 data, alb-IFN 900 microg and 1200 microg every 2 weeks were selected for two ongoing phase 3 trials in IFN-naïve patients with genotype 1 and 2/3 CHC. Albinterferon alfa-2b exhibits high antiviral activity, and appears to offer safety/tolerability comparable to the current standard of care, and health-related quality-of-life benefits in patients with CHC. Its ability to maintain drug concentrations above the 90% effective concentration over prolonged dosing intervals suggests that it may be an ideal partner for combination therapy with direct antiviral agents in CHC. The results of the phase 3 trials are eagerly anticipated as they should greatly clarify the future role of alb-IFN in the treatment of CHC.Current Medical Research and Opinion 05/2009; 25(4):991-1002. · 2.37 Impact Factor
Recombinant Fc-IL-18BPc Isoform Inhibits IL-18-Induced
Kwangwon Hong,1* Kwangjun Oh,1,2* Siyoung Lee,1Jaewoo Hong,1Jida Choi,1Areum Kwak,1
Dongjun Kang,1Eunsom Kim,1Seunghyun Jo,1Hyunjhung Jhun,1and Soohyun Kim1
IL-18 is a pro-inflammatory cytokine that is produced from T cells and NK cells. IL-18 has been implicated in the
pathogenesis of various inflammatory and cardiovascular diseases. IL-18 binding protein (IL-18BP) is a natural
inhibitor of IL-18 that possesses higher affinity to IL-18 than that of the IL-18 receptor alpha chain on the cell
surface. Human isoform a and c among four isoforms of IL-18BPs have an inhibitory effect on IL-18-induced
cytokines whereas mouse IL-18BP isoforms exist only in two isoforms: c and d. Fc-fusion protein is a molecule in
which the immunoglobulin Fc is fused genetically to a protein of interest, such as an extracellular domain of a
receptor, ligand, or enzyme. In this study, we expressed and purified human Fc-IL-18BPa and c isoforms from
CHO-DG44 cells and their biological activities were compared to each other. This is the first time that expressed
recombinant human Fc-IL-18BPc has been examined for its biological activity on IL-18-induced IFNg in human
PBMC and IL-6 in A549/IL-18Rb.
logically inactive pro-form (pro-IL-18) without a classical
signal peptide. The pro-IL-18 is activated by the IL-1b con-
verting enzyme, caspase-1.(2–4)In the presence of IL-12, IL-18
prominently induces the expression of interferon gamma
(IFNg) from T cells and NK cells, thereby promoting Th1-type
IL-18 has been implicated in the pathogenesis of various in-
flammatory disorders and processes, including diabetes melli-
tus, atherosclerosis, sepsis, chronic liver disease, and several
autoimmune diseases, including rheumatoid arthritis, multiple
sclerosis, and Crohn’s disease.(6–13)Cells expressing IL-18 have
been reported within neuroinflammatory lesions in human
multiplesclerosis,(6)and bothIL-18 andcaspase-1mRNA levels
were considerably elevated in Lewis rats with experimental
autoimmune encephalomyelitis, which is a mouse model for
multiple sclerosis.(9)In animal models of rheumatoid arthritis,
a combination of IL-18 with a neutralizing anti-IL-18 antibody
significantly reduced joint swelling.(14)
It has been shown that IL-18 can be a predictive biomarker
for human death due to cardiovascular disease.(15,16)The
plasma IL-18 level is correlated with a number of risk factors
for cardiovascular disease independent of C-reactive protein
and IL-6, including LDL cholesterol and triglyceride levels.(8)
riginally named IFNg-inducing factor,(1)IL-18 is a
pro-inflammatory cytokine that is produced as a bio-
IL-18 has also been implicated in the pathogenesis of athero-
sclerosis. As circulating levels of IL-18 are higher in subjects
with increased carotid- intima-media thickness,(17)increased
IL-18 expression has been related with unstable plaque.(18,19)
IL-18 binding protein (IL-18BP) is a natural antagonist for
IL-18.(13)In fact, the balance between circulating IL-18 and IL-
18BP affects the severity of some inflammatory diseases.(20)
Transgenic mice overexpressing human IL-18BPa (IL-18BPa
Tg) produce high levels of bioactive IL-18BPa in the circula-
tion, providing protection against inflammatory stimuli.(21)
Although IL-18BP slightly resembles the IL-1 and IL-18
membrane receptors, it is not a variant of the extracellular
ligand-binding portion of these receptors. IL-18BP is a distinct
gene composed of a single immunoglobulin domain.(13,22)
Interestingly, several poxviruses encode IL-18BP ortholo-
gues as virulence factors that contribute to immune escape by
suppressing antiviral immune responses of the host.(23–26)
a pivotal role in viral infection as a mediator of cytotoxic
immune responses. Although IL-18BP is produced constitu-
tively, its expression is noticeably increased by IFNg through
two transcription factors, IFN regulatory factor 1 (IRF1) and
CCAAT/enhancer binding protein beta (C/EBPb). In addi-
tion, these provide negative feedback.(27–29)
There are several reports that IL-18BP can prevent or at-
tenuate the development of disease in animal models(30,31);
however the secreted amount of IL-18BP induced by IFNg
seems insufficient to defeat the quantity of IL-18 in circulation
1Laboratory of Cytokine Immunology, Department of Biomedical Sciences and Technology;2Department of Orthopaedic Surgery, Konkuk
University Medical Center, School of Medicine, Konkuk University, Seoul, Korea.
*These authors contributed equally to this work.
Volume 31, Number 2, 2012
ª Mary Ann Liebert, Inc.
under certain pathological circumstances.(32)Four human
isoforms of IL-18BP have been characterized (isoforms a, b, c,
and d) but only isoforms IL-18BPa and IL-18BPc have affinity
to IL-18 and down-regulate its function in vitro.(33)Similar to
human IL-18BP, murine IL-18BPc and murine IL-18BPd
neutralize the IL-18 activity at equal-molar concentrations.(33)
Fc fusion proteins are molecules in which the immuno-
globulin Fc is fused genetically to a protein of interest. Fc
fusion proteins have some antibody-like properties such as
long serum half-life and easy expression and purification,
making them an attractive platform for therapeutic drugs.(34–
36)An Fc fusion-based drug, such as Enbrel,?is currently on
the market, and many more are in different stages of clinical
trials, demonstrating that Fc fusion proteins have become an
alternative to monoclonal antibody therapeutics. In this
study, we used pCAG.neo-hIgG1-Fc vector with a strong
chicken beta-actin promoter and expressed recombinant Fc-
IL-18BPa and c purified for experimental use.
Materials and Methods
PCR and molecular cloning
Human IL-18BPa and IL-18BPc cDNA was amplified from
vectors previously constructed(13)with the common forward
primer containing XbaI recognition site and Kozak consensus
GGAC-3’) and MluI site containing reverse primer for IL-
18BPa (5’ATTTACGCGTACCCTGCT GCTGTGGACT-3’) or
PCR reaction was performed as described above. Inserts were
digested with XbaI and MluI and ligated to pCAG.neo-hIgG1-
cloned vectors was also analyzed and the vectors were named
Fc-IL-18BPa and Fc-IL-18BPc.
The dihydrofolate reductase (DHFR)-deficient Chinese
hamster ovary (CHO) cell line, DG44, was used for stable
expression of recombinant Fc-IL-18BP chimeric proteins. The
CHO-DG44 cells were grown at 5% CO2, 37?C in DMEM/F12
(Invitrogen, Carlsbad, CA) supplemented with hypoxanthine
(10mg/L), thymidine (10mg/L), glycine (50mg/L), gluta-
mine (587mg/L), glucose (4.5mg/L), 10% FBS, and antibi-
Production of chimeric recombinant protein
hFc-IL-18BPplasmids wereco-transfected withpSV-DHFR
vector (ATCC, Manassas, VA) into DHFR-deficient CHO cell
line (DG44), and stably transformed cell lines were selected in
a medium containing G418 (500mg/mL) and subsequently
subjected to methotrexate (MTX) selection for gene amplifi-
cation, as described previously.(37)The CHO cells secreting
Fc-IL-18BP weregrown in serum-freemedium (CHO-SSFMII,
Invitrogen), and the culture supernatant was subjected to af-
finity chromatography on protein A-sepharose 4B column
(GE Healthcare, Piscataway, NJ), as described previously.(37)
Recombinant human IL-18 (100ng, YbdYbiotech, Seoul,
Korea) was incubated with freshly purified recombinant Fc-
IL-18BPa or Fc-IL-18BPc (500ng) in 50mL volume of PBS for
protein A-agarose beads for 4h at 4?C. The precipitate was
subjected to SDS-PAGE for Western blot analysis with rabbit
anti-human IL-18 antibody (YbdYbiotech).
Bioassay and ELISA
Human PBMC was isolated as previously described.(38)
1.0·106PBMCs were seeded in a 96-well plate containing 10%
IL-18BPa or Fc-IL-18BPc (2mg/mL) for 30min at room temper-
manufacturer’s manual (R&D Systems, Minneapolis, MN).
A549-IL-18Rb cells were cultured as previously de-
scribed.(38)2.5·104cells were seeded in a 96-well plate
containing 10% FBS. IL-18 (50ng/mL) was mixed with Fc-IL-
18BPa or Fc-IL-18BPc (2mg/mL) for 30min at room temper-
ature and added to A549-IL-18Rb cells overnight. The culture
supernatant was harvested for measurement ofIL-6 byELISA
Data are expressed as means–SEM. Statistical significance
of differences was analyzed by the unpaired, two-tailed Stu-
dent’s t test. Values of p<0.05 were considered statistically
Expression and purification of recombinant
The schematic structures of Fc-IL-18BPa and Fc-IL-18BPc
are shown in Figure 1. The recombinant human Fc-IL-18BPa
and c were purified through protein A-agarose columns.
Eluted fractions of recombinant Fc-IL-18BPa and c were
subjected to SDS-PAGE and silver-staining in non-reduced or
reduced conditions. The molecular size of the non-reduced
was 55kDa (Fig. 2A). Western blotting against IL-18BP and
human IgG-Fc confirmed that those bands are Fc-IL-18BPa
(Fig. 2B). In reduced conditions, the affinity-purified IL-18BPa
and c appeared as a single band with silver staining and
Western blot analysis.
Fc-IL-18BP binds to IL-18BP
We performed immunoprecipitation of recombinant IL-18
with purified Fc-IL-18BPa or Fc-IL-18BPc to confirm whether
purified proteins bind to IL-18 properly. Both Fc-IL-18BPa and
Fc-IL-18BPc were precipitated with recombinant IL-18. Re-
combinant Fc-IL-18BPa and Fc-IL-18BPc protein was bound to
mature IL-18 (20kDa) and precursor IL-18 (30kDa) that was
not fully cleaved with Tobacco Etch virus (TEV) enzyme (Fig.
3A). We therefore repeated the experiment with precursor IL-
18, and the result showed that precursor IL-18 was also pre-
cipitated with Fc-IL-18BPa or Fc-IL-18BPc (Fig. 3B).
Fc-IL-18BP decreases the activity of IL-18
IL-18 induces IFNg from human PBMCs in combination
with IL-12. Therefore, we stimulated human PBMCs with
100HONG ET AL.
IL-12 and IL-18 in the presence or absence of recombinant Fc-
IL-18BPa and c. IFNg was not induced when IL-12 was solely
treated; however it was highly induced when IL-12 was
treated in combination with IL-18. Fc-IL-18BPa and c suffi-
ciently suppressed IFNg production in human PBMCs. The
inhibitory effect of Fc-IL-18BPa was more significant than Fc-
IL-18BPc (Fig. 4A). The combination of Fc-IL-18BPa and IL-
18BPc also decreased IL-12 and IL-18 induced secretion of
IFNg (data not shown). We further confirmed the activity of
Fc-IL-18BPs with A549-IL-18Rb cells. IL-18 was treated on
protein A-agarose column and eluted fractions were visualized by silver-staining in reduced or non-reduced conditions. The
molecular size of the non-reduced protein was approximately 130kDa (dimmer) while reduced protein was 55kDa
(monomer). (B) Western blotting with rabbit anti-IL-18BP was also performed to specify the recombinant Fc-IL-18BPa and c
proteins. The data represent one of two independent experiments.
Purification of recombinant human Fc-IL-18BPs. (A) Recombinant human Fc-IL-18BPa and c were purified with
coupled by disulfide bonds. Both Fc-IL-18BPa (A) and Fc-IL-18BPc (B) are continuously linked in a row with N-terminal IL-
18BP, hinge, CH1, and CH2 domains.
Structures of Fc-IL-18BPa and Fc-IL-18BPc. Fc-IL-18BP proteins are expected to be expressed in homodimeric form
BIOLOGICAL ACTIVITY OF HUMAN RECOMBINANT Fc-IL-18BPc101
18Rb cells treated with IL-18 induced a high level of IL-6;
the presence of Fc-IL-18BPa or Fc-IL-18BPc (Fig. 4B).
is a significant domain for IL-18 receptor alpha chain binding
to its ligand.(13,22)However, IL-18BP is a distinct protein from
the IL-1 and IL-18 receptor families and locates in chromo-
some 11q13 at the inverted position of the nuclear mitotic
apparatus protein-1.(13)The human IL-18BP genomic DNA
encodes at least four different isoforms derived from alter-
native splicing isolated from several human cDNA libraries.
Two murine IL-18BP isoforms were found and murine IL-
18BPc and d are similar to human IL-18BPc and a, respec-
IL-18BP is a unique soluble protein, lacking a transmem-
brane domain, and it specifically binds to IL-18 with an ex-
traordinarily high affinity (100 picomolar range).(33)IL-18BP
neutralizes the bioactivity of IL-18 with an equimolar ratio
and shares high homology with several poxviral proteins,
which indicates the importance of this molecule in resistance
to viral infections.(13,23–26)IL-18 has been reported to be
related to various diseases, including diabetes mellitus, ath-
erosclerosis, sepsis, chronic liver disease, rheumatoid arthri-
tis, multiple sclerosis, and Crohn’s disease.(6–13)IL-18 is also
related to cardiovascular diseases.(15,16)Fc-IL-18BP can be
used in studies related to those diseases; furthermore this can
be a substitutive or additive drug.
In this study, we expressed Fc-IL-18BPa and c isoforms and
examined their biological activities on the inhibition of IL-18-
combinant Fc-IL-18BPa or Fc-IL-18BPc. Both Fc-IL-18BPa and Fc-IL-18BPc precipitated precursor and mature IL-18 (indicated
by arrows) compared to negative control in the first lane. (A) Recombinant Fc-IL-18BPa and Fc-IL-18BPc protein were bound
to mature IL-18 (20kDa) and proIL-18 (30kDa) that was not fully cleaved with TEV enzyme. (B) Precursor IL-18 was also
immunoprecipitated with Fc-IL-18BPa and Fc-IL-18BPc. The data represent one of three independent experiments.
IL-18 was specifically immunoprecipitated by Fc-IL-18BP. Immunoprecipitation of IL-18 was performed with re-
IFNg in human PBMC. (B) The stimulation of A549-IL-18Rb cells with IL-18 induces IL-6. The level of IL-6 was also
significantly suppressed by Fc-IL-18BPs. ***p<0.001 (n=3 per group). The data represent one of two independent experi-
Fc-IL-18BP decreases the biological activity of IL-18. (A) Both Fc-IL-18BPs decreased the IL-18 plus IL-12 induced
102 HONG ET AL.
induced cytokines. As described above, recombinant Fc-IL-
18BP proteins obtain some antibody-like properties such as
long serum half-life and easy expression and purification,
making them attractive for use in different experimental dis-
This work was supported by Konkuk University.
Author Disclosure Statement
The authors have no financial interests to disclose.
1. Nakamura K, Okamura H, Nagata K, Komatsu T, and
Tamura T: Purification of a factor which provides a costi-
mulatory signal for gamma interferon production. Infect
2. Dinarello CA, and Fantuzzi G: Interleukin-18 and host de-
fense against infection. J Infect Dis 2003;187 Suppl 2:S370–
3. Ghayur T, Banerjee S, Hugunin M, Butler D, Herzog L,
Carter A, Quintal L, Sekut L, Talanian R, Paskind M, Wong
W, Kamen R, Tracey D, and Allen H: Caspase-1 processes
IFN-gamma-inducing factor and regulates LPS-induced
IFN-gamma production. Nature 1997;386:619–623.
4. Gu Y, Kuida K, Tsutsui H, Ku G, Hsiao K, Fleming MA,
Hayashi N, Higashino K, Okamura H, Nakanishi K, Kur-
imoto M, Tanimoto T, Flavell RA, Sato V, Harding MW,
Livingston DJ, and Su MS: Activation of interferon-gamma
inducing factor mediated by interleukin-1beta converting
enzyme. Science 1997;275:206–209.
5. Okamura H, Tsutsi H, Komatsu T, Yutsudo M, Hakura A,
Tanimoto T, Torigoe K, Okura T, Nukada Y, Hattori K, et al:
Cloning of a new cytokine that induces IFN-gamma pro-
duction by T cells. Nature 1995;378:88–91.
6. Balashov KE, Rottman JB, Weiner HL, and Hancock WW:
CCR5(+) and CXCR3(+) T cells are increased in multiple
sclerosis and their ligands MIP-1alpha and IP-10 are ex-
pressed in demyelinating brain lesions. Proc Natl Acad Sci
7. Corbaz A, ten Hove T, Herren S, Graber P, Schwartsburd B,
Belzer I, Harrison J, Plitz T, Kosco-Vilbois MH, Kim SH,
Dinarello CA, Novick D, van Deventer S, and Chvatchko Y:
IL-18-binding protein expression by endothelial cells and
macrophages is up-regulated during active Crohn’s disease.
J Immunol 2002;168:3608–3616.
8. Hulthe J, McPheat W, Samnegard A, Tornvall P, Hamsten A,
and Eriksson P: Plasma interleukin (IL)-18 concentrations is
elevated in patients with previous myocardial infarction and
related to severity of coronary atherosclerosis independently
of C-reactive protein and IL-6. Atherosclerosis 2006;188:
9. Jander S, and Stoll G: Differential induction of interleukin-
12, interleukin-18, and interleukin-1beta converting enzyme
mRNA in experimental autoimmune encephalomyelitis of
the Lewis rat. J Neuroimmunol 1998;91:93–99.
10. Ludwiczek O, Kaser A, Novick D, Dinarello CA, Rubinstein
M, Vogel W, and Tilg H: Plasma levels of interleukin-18 and
interleukin-18 binding protein are elevated in patients with
chronic liver disease. J Clin Immunol 2002;22:331–337.
11. Mallat Z, Corbaz A, Scoazec A, Graber P, Alouani S, Espo-
sito B, Humbert Y, Chvatchko Y, and Tedgui A: Interleukin-
18/interleukin-18 binding protein signaling modulates ath-
erosclerotic lesion development and stability. Circ Res 2001;
12. Moller B, Nguyen TT, Kessler U, Kaltwasser JP, Hoelzer D,
and Ottmann OG: Interleukin-10 expression: is there a ne-
glected contribution of CD8+ T cells in rheumatoid arthritis
joints? Clin Exp Rheumatol 2002;20:813–822.
13. Novick D, Kim SH, Fantuzzi G, Reznikov LL, Dinarello CA,
and Rubinstein M: Interleukin-18 binding protein: a novel
modulator of the Th1 cytokine response. Immunity 1999;10:
14. Joosten LA, van De Loo FA, Lubberts E, Helsen MM, Netea
MG, van Der Meer JW, Dinarello CA, and van Den Berg WB:
An IFN-gamma-independent proinflammatory role of IL-18
in murine streptococcal cell wall arthritis. J Immunol 2000;
15. Blankenberg S, Tiret L, Bickel C, Peetz D, Cambien F, Meyer
J, and Rupprecht HJ: Interleukin-18 is a strong predictor of
cardiovascular death in stable and unstable angina. Circu-
16. Thompson SR, Novick D, Stock CJ, Sanders J, Brull D,
Cooper J, Woo P, Miller G, Rubinstein M, and Humphries
SE: Free interleukin (IL)-18 levels, and the impact of IL18
and IL18BP genetic variation, in CHD patients and healthy
men. Arterioscler Thromb Vasc Biol 2007;27:2743–2749.
17. Yamagami H, Kitagawa K, Hoshi T, Furukado S, Hougaku
H, Nagai Y, and Hori M: Associations of serum IL-18 levels
with carotid intima-media thickness. Arterioscler Thromb
Vasc Biol 2005;25:1458–1462.
18. Gerdes N, Sukhova GK, Libby P, Reynolds RS, Young JL,
and Schonbeck U: Expression of interleukin (IL)-18 and
functional IL-18 receptor on human vascular endothelial
cells, smooth muscle cells, and macrophages: implications
for atherogenesis. J Exp Med 2002;195:245–257.
19. Mallat Z, Corbaz A, Scoazec A, Besnard S, Leseche G,
Chvatchko Y, and Tedgui A: Expression of interleukin-18 in
human atherosclerotic plaques and relation to plaque in-
stability. Circulation 2001;104:1598–1603.
20. Mazodier K, Marin V, Novick D, Farnarier C, Robitail S,
Schleinitz N, Veit V, Paul P, Rubinstein M, Dinarello CA,
Harle JR, and Kaplanski G: Severe imbalance of IL-18/IL-
18BP in patients with secondary hemophagocytic syndrome.
21. Fantuzzi G, Banda NK, Guthridge C, Vondracek A, Kim SH,
Siegmund B, Azam T, Sennello JA, Dinarello CA, and Arend
WP: Generation and characterization of mice transgenic for
human IL-18-binding protein isoform a. J Leukoc Biol 2003;
22. Azam T, Novick D, Bufler P, Yoon DY, Rubinstein M, Di-
narello CA, and Kim SH: Identification of a critical Ig-like
domain in IL-18 receptor alpha and characterization of a
functional IL-18 receptor complex. J Immunol 2003;171:
23. Born TL, Morrison LA, Esteban DJ, VandenBos T, Thebeau
LG, Chen N, Spriggs MK, Sims JE, and Buller RM: A pox-
virus protein that binds to and inactivates IL-18, and inhibits
NK cell response. J Immunol 2000;164:3246–3254.
24. Nazarian SH, Rahman MM, Werden SJ, Villeneuve D, Meng
X, Brunetti C, Valeriano C, Wong C, Singh R, Barrett JW,
Xiang Y, and McFadden G: Yaba monkey tumor virus en-
codes a functional inhibitor of interleukin-18. J Virol 2008;82:
BIOLOGICAL ACTIVITY OF HUMAN RECOMBINANT Fc-IL-18BPc103
25. Smith VP, Bryant NA, and Alcami A: Ectromelia, vaccinia
and cowpox viruses encode secreted interleukin-18-binding
proteins. J Gen Virol 2000;81:1223–1230.
26. Xiang Y, and Moss B: IL-18 binding and inhibition of in-
terferon gamma induction by human poxvirus-encoded
proteins. Proc Natl Acad Sci USA 1999;96:11537–11542.
27. Hurgin V, Novick D, and Rubinstein M: The promoter of IL-
18 binding protein: activation by an IFN-gamma -induced
complex of IFN regulatory factor 1 and CCAAT/enhancer
binding protein beta. Proc Natl Acad Sci USA 2002;99:
28. Muhl H, Kampfer H, Bosmann M, Frank S, Radeke H, and
Pfeilschifter J: Interferon-gamma mediates gene expression
of IL-18 binding protein in nonleukocytic cells. Biochem
Biophys Res Commun 2000;267:960–963.
29. Paulukat J, Bosmann M, Nold M, Garkisch S, Kampfer H,
Frank S, Raedle J, Zeuzem S, Pfeilschifter J, and Muhl H:
Expression and release of IL-18 binding protein in response
to IFN-gamma. J Immunol 2001;167:7038–7043.
30. Banda NK, Vondracek A, Kraus D, Dinarello CA, Kim SH,
Bendele A, Senaldi G, and Arend WP: Mechanisms of inhi-
bition of collagen-induced arthritis by murine IL-18 binding
protein. J Immunol 2003;170:2100–2105.
31. Faggioni R, Cattley RC, Guo J, Flores S, Brown H, Qi M, Yin
S, Hill D, Scully S, Chen C, Brankow D, Lewis J, Baikalov C,
Yamane H, Meng T, Martin F, Hu S, Boone T, and Senaldi G:
IL-18-binding protein protects against lipopolysaccharide-
induced lethality and prevents the development of Fas/Fas
ligand-mediated models of liver disease in mice. J Immunol
32. Novick D, Elbirt D, Dinarello CA, Rubinstein M, and
Sthoeger ZM: Interleukin-18 binding protein in the sera of
patients with Wegener’s granulomatosis. J Clin Immunol
33. Kim SH, Eisenstein M, Reznikov L, Fantuzzi G, Novick D,
Rubinstein M, and Dinarello CA: Structural requirements
of six naturally occurring isoforms of the IL-18 binding
protein to inhibit IL-18. Proc Natl Acad Sci USA 2000;
34. Osborn BL, Olsen HS, Nardelli B, Murray JH, Zhou JX,
Garcia A, Moody G, Zaritskaya LS, and Sung C: Pharma-
cokinetic and pharmacodynamic studies of a human serum
albumin-interferon-alpha fusion protein in cynomolgus
monkeys. J Pharmacol Exp Ther 2002;303:540–548.
35. Rustgi VK: Albinterferon alfa-2b, a novel fusion protein of
human albumin and human interferon alfa-2b, for chronic
hepatitis C. Curr Med Res Opin 2009;25:991–1002.
36. Zeuzem S, Yoshida EM, Benhamou Y, Pianko S, Bain VG,
Shouval D, Flisiak R, Rehak V, Grigorescu M, Kaita K,
McHutchison JG: Albinterferon alfa-2b dosed every two or
four weeks in interferon-naive patients with genotype 1
chronic hepatitis C. Hepatology 2008;48:407–417.
37. Ryu CJ, Padlan EA, Jin BR, Yoo OJ, and Hong HJ: A hu-
manized antibody with specificity for hepatitis B surface
antigen. Hum Antibodies Hybridomas 1996;7:113–122.
38. Kim SH, Han SY, Azam T, Yoon DY, and Dinarello CA:
Interleukin-32: a cytokine and inducer of TNFalpha. Im-
39. Kim SH, Azam T, Yoon DY, Reznikov LL, Novick D, Ru-
binstein M, and Dinarello CA: Site-specific mutations in the
mature form of human IL-18 with enhanced biological ac-
tivity and decreased neutralization by IL-18 binding protein.
Proc Natl Acad Sci USA 2001;98:3304–3309.
Address correspondence to:
Dr. Soohyun Kim
Laboratory of Cytokine Immunology
Department of Biomedical Sciences and Technology
1 Hwayang-dong, Gwangjin-gu
Received: September 8, 2011
Accepted: November 22, 2011
104 HONG ET AL.