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Vol. 52, No. 3, March 2005, pp 984–986
© 2005, American College of Rheumatology
complex–associated glomerulonephritis and proteinuria, as well
as inflammation of the salivary gland, liver, and lung—all comparable with, if not worse than, the findings in their WT counterparts (Figure 1B and results not shown). Expression of IFN␥ in
the spleens and kidneys was comparable between WT and KO
animals, as was their overall mortality (survival at 24 weeks 6 of 12
WT animals and 7 of 14 KO animals).
Thus, IL-18R␣ is not required for the development of
murine lupus, as judged by autoantibody production and endorgan inflammation and dysfunction, at least in this severe
autoimmunity model. These results indicate that, although it may
in some contexts play a pathogenic role (8), IL-18 is not an
essential mediator of either autoantibody generation or endorgan inflammation in lupus, and suggest that previous findings
with a partially backcrossed IL-18R␣ allele against the MRL/lpr
background (9) were confounded by the incomplete genetics of
the backcross, which likely allowed protective 129 genes, perhaps
associated with chromosome 1, to segregate with IL-18R␣ deficiency. Alternatively, our findings may reflect differences in
housing conditions, where different diets, bacterial or other
microorganismal flora, etc. may alter ongoing Th1/Th2 cytokine
or other inflammatory responses, as has been suggested to explain
the differences in penetrance of the 16/6 antiidiotype murine
lupus model in different environments (17) as well as in models of
other autoimmune diseases, such as diabetes in NOD mice (18).
As such, the potential influence of bacterial flora and other
environmental factors in the production, activity, and effects of
endogenous IL-18 in murine lupus may be of interest.
Similarly, it is interesting to note that the 129 genome,
including chromosome 1, has generally been considered to harbor
enhancers of autoimmunity, particularly when studied against the
C57BL/6 genome (19), while the present results suggest that some
129 genes may be protective, at least on the MRL/lpr background.
These observations suggest differential interactions between such
disease-modifying 129 loci and the different background strains,
e.g., C57BL/6 versus MRL. Since such differences may offer
insight into the context-specific roles of such autoimmunity genes,
further studies addressing the potential impact of 129 loci upon
autoimmunity in other inbred mouse strains, including MRL, will
likely be of continued interest.
Finally, another study has demonstrated that intramuscular vaccination of young MRL/lpr mice with a complementary
DNA (cDNA) encoding murine IL-18 elicited significant reductions in lymphoproliferation, renal disease, and mortality (20).
Since these effects were associated with the development of
anti–IL-18 autoantibodies, the authors concluded that neutralization of IL-18 activity was responsible for the protective effect.
However, autoantibodies to cytokines are common in MRL/lpr, as
well as other autoimmune-prone, mice (21), and separate studies
have indicated that IL-18 may have an immunosuppressive role in
lupus, acting in synergy with IL-12 in the inhibition of autoantibody production (22). Thus, perhaps IL-18 cDNA vaccination
resulted in disease protection due not to anti–IL-18 autoantibody
generation, but to a direct inhibitory effect of the ectopically
generated IL-18 upon antinuclear autoantibody production. In
contrast, results of a previous study with intraperitoneal administration of Escherichia coli–derived recombinant IL-18, which
appeared to exacerbate disease (8), may perhaps have reflected
contaminating elements in the preparation of recombinant cytokine (e.g., bacterial lipopolysaccharides, etc.), which could initiate
and/or promote autoimmune responses (23), and/or differences
DOI 10.1002/art.20961
Interleukin-18 receptor signaling is not required for
autoantibody production and end-organ disease in
murine lupus
In both human and murine lupus, interleukin-18 (IL18) has emerged as a prominent pathogenic and therapeutic
target: its serum levels correlate with disease activity (1–6), and it
is known to act in synergy with IL-12 for the induction, in T cells,
of interferon-␥ (IFN␥), a pathogenic cytokine in this disease (7).
Intraperitoneal administration of recombinant IL-18 or of IL-18
plus IL-12 has been demonstrated to exacerbate renal disease and
production of inflammatory cytokines in the MRL/lpr murine
lupus model (8), and Kinoshita et al have recently demonstrated
the reduced development of autoantibodies, renal disease, and
mortality in lupus-prone animals that are homozygous for a
targeted IL-18 receptor ␣ (IL-18R␣) allele (9). However, it is
notable that those authors generated IL-18R␣–deficient lupusprone animals via intercross-backcross between the original IL18R␣–deficient strain on the 129 background and the target
MRL/lpr strain, and only for 3 generations. Use of this strategy
theoretically might generate animals with ⬎94% MRL/lpr genes;
however, it could have easily generated animals with significantly
fewer. Indeed, the IL-18R␣ gene is located on chromosome 1,
which harbors strong disease-modfying loci in both human and
murine lupus (10), and it is unclear from the findings of Kinoshita
et al whether the reduction in disease parameters truly reflects
IL-18R␣ deficiency as opposed to the presence of diseaseprotective 129 loci, some potentially on chromosome 1.
To address this issue, we have generated congenic
MRL/lpr animals deficient for IL-18R␣ by backcrossing mice
with the same IL-18R␣–deficient allele (11) against mice of
the MRL/lpr background (both from The Jackson Laboratory,
Bar Harbor, ME) over 8 generations, using a speed-congenic
strategy which ensures MRL homozygosity at all 24 proposed
MRL disease susceptibility loci, as well as IgH, H-2, CD95, and
importantly, chromosome 1 (12–16). IL-18R␣⫹/⫺ MRL/lpr animals generated in this manner were homozygotic for MRL
chromosome 1 at markers D1Mit169 (15.0 cM) and D1Mit380
(36.9 cM), indicating the development of animals with an approximately ⱕ22-cM 129 congenic interval containing IL-18R␣ (at
⬃20.6 cM). These mice were intercrossed to generate IL18R␣⫹/⫹ (wild type [WT]) and IL-18R␣⫺/⫺ (knockout [KO])
MRL/lpr animals. As expected, RNA transcript for IL-18R␣ was
detectable by reverse transcriptase–polymerase chain reaction in
the spleens of WT, but not KO, animals (results not shown).
Animals were observed and assessed over time, by established
protocols (16), for the development of lupus.
Surprisingly, KO animals developed full-blown lupus,
essentially indistinguishable from that in their WT counterparts:
as assessed at 12 weeks and 18 weeks of age, they had developed
comparable, and sometimes increased, levels of anti–doublestranded DNA and rheumatoid factor (Figure 1A) as well as
hypergammaglobulinemia of all isotypes, and comparable or
increased degrees of lymphadenopathy due to the accumulation
of CD3⫹,CD4⫺,CD8⫺,B220⫹ T cells (mean ⫾ SD weight of
spleens and lymph nodes of WT versus KO animals 231 ⫾ 74
versus 259 ⫾ 82 mg and 593 ⫾ 116 versus 688 ⫾ 415 mg,
respectively, at 12 weeks of age). Furthermore, KO animals
developed full-blown end-organ disease, including immune
Figure 1. Serologic and histopathologic development of lupus in interleukin-18 receptor ␣ (IL-18␣)–deficient MRL/lpr mice. A, Sera from
12-week-old IL-18R␣–wild-type (WT; n ⫽ 8) or -deficient (knockout [KO]; n ⫽ 12) animals were assessed by enzyme-linked immunosorbent assay
for anti–double-stranded DNA (anti-dsDNA) and ␬ chain–specific rheumatoid factor autoantibody specificities at 1:100 dilution, as well as for total
serum IgG isotypes as previously described (16). Dashed lines indicate thresholds for positivity (3 SD above the mean optical density [OD] in sera
from non-autoimmune BALB/c mice). All sera were also positive for anti-dsDNA by Crithidia luciliae immunofluorescence. B, Representative
end-organ inflammation in the salivary glands and kidneys of 18-week-old WT versus KO mice. Note the development, in both WT and KO animals,
of significant mononuclear infiltrates in the periacinar regions of the salivary glands, occupying the majority of the micrographs except for the
vascular and ductal regions, as well as intact acinar complexes along the upper right edge. Note also moderate-to-severe hypercellularity and
mesangial thickening of the renal glomeruli. Perivasculitis is prominent in both organs. Renal IgG deposits were assessed by direct immunofluorescence; note the presence of IgG deposition in both the renal glomeruli and the tubules of both WT and KO animals. Non-autoimmune C57BL/6
mice did not develop such inflammation of any organ, or renal IgG deposition (results not shown). Each panel reflects a different animal,
representative of 10–12 animals examined per genotype (original magnification ⫻ 200).
in the specific level of systemic IL-18 achieved, which may
account for a pro- versus antiinflammatory effect (22). As such,
the role of IL-18 may be varied and context-dependent in lupus,
but given our present results, it nonetheless appears largely
dispensable for disease pathogenesis in the MRL/lpr model.
Therefore, as is the case for type I IFN, caution should be
exercised in the interpretation of the results of studies that equate
cytokine overexpression with pathogenicity and that utilize nonideal genetic intercrosses to assess the role of specific mutant loci
in polygenic diseases (16).
Supported by the Siteman Cancer, Rheumatic Diseases, Diabetes
Research and Training, the Digestive Research Core Centers of the
Washington University School of Medicine (grant DK52574), the NIH
(grants AI-01803 and AI-057471), and the Lupus Research Institute. Dr.
Peng’s work was supported by an Arthritis Investigator award from the
Arthritis Foundation.
Ling Lin, MS
Stanford L. Peng, MD, PhD
Washington University School of Medicine
St. Louis, MO
1. Wong CK, Li EK, Ho CY, Lam CW. Elevation of plasma
interleukin-18 concentration is correlated with disease activity in
systemic lupus erythematosus. Rheumatology (Oxford) 2000;39:
2. Neumann D, del Giudice E, Ciaramella A, Boraschi D, Bossu P.
Lymphocytes from autoimmune MRL lpr/lpr mice are hyperresponsive to IL-18 and overexpress the IL-18 receptor accessory
chain. J Immunol 2001;166:3757–62.
3. Amerio P, Frezzolini A, Abeni D, Teofoli P, Girardelli CR, de Pita
O, et al. Increased IL-18 in patients with systemic lupus erythematosus: relations with Th-1, Th-2, pro-inflammatory cytokines and
disease activity: IL-18 is a marker of disease activity but does not
correlate with pro-inflammatory cytokines. Clin Exp Rheumatol
4. Robak E, Robak T, Wozniacka A, Zak-Prelich M, Sysa-Jedrzejowska A, Stepien H. Proinflammatory interferon-␥–inducing
monokines (interleukin-12, interleukin-18, interleukin-15): serum
profile in patients with systemic lupus erythematosus. Eur Cytokine Net 2002;13:364–8.
5. Faust J, Menke J, Kriegsmann J, Kelley VR, Mayet WJ, Galle PR,
et al. Correlation of renal tubular epithelial cell–derived interleukin-18 up-regulation with disease activity in MRL-Faslpr mice with
autoimmune lupus nephritis. Arthritis Rheum 2002;46:3083–95.
6. Wong CK, Ho CY, Li EK, Tam LS, Lam CW. Elevated production
of interleukin-18 is associated with renal disease in patients with
systemic lupus erythematosus. Clin Exp Immunol 2002;130:345–
7. Shlomchik MJ, Craft JE, Mamula MJ. From T to B and back
again: positive feedback in systemic autoimmune disease. Nat Rev
Immunol 2001;1:147–53.
8. Esfandiari E, McInnes IB, Lindop G, Huang FP, Field M,
Komai-Koma M, et al. A proinflammatory role of IL-18 in the
development of spontaneous autoimmune disease. J Immunol
Kinoshita K, Yamagata T, Nozaki Y, Sugiyama M, Ikoma S,
Funauchi M, et al. Blockade of IL-18 receptor signaling delays the
onset of autoimmune disease in MRL-Faslpr mice. J Immunol
Kelly JA, Moser KL, Harley JB. The genetics of systemic lupus
erythematosus: putting the pieces together. Genes Immun 2002;3
Suppl 1:S71–85.
Hoshino K, Tsutsui H, Kawai T, Takeda K, Nakanishi K, Takeda
Y, et al. Cutting edge: generation of IL-18 receptor-deficient mice:
evidence for IL-1 receptor-related protein as an essential IL-18
binding receptor. J Immunol 1999;162:5041–4.
Gu L, Weinreb A, Wang XP, Zack DJ, Qiao JH, Weisbart R, et al.
Genetic determinants of autoimmune disease and coronary vasculitis in the MRL-lpr/lpr mouse model of systemic lupus erythematosus. J Immunol 1998;161:6999–7006.
Nishihara M, Terada M, Kamogawa J, Ohashi Y, Mori S, Nakatsuru S, et al. Genetic basis of autoimmune sialadenitis in MRL/lpr
lupus-prone mice: additive and hierarchical properties of polygenic inheritance. Arthritis Rheum 1999;42:2616–23.
Vidal S, Kono DH, Theofilopoulos AN. Loci predisposing to
autoimmunity in MRL-Faslpr and C57BL/6-Faslpr mice. J Clin
Invest 1998;101:696–702.
Watson ML, Rao JK, Gilkeson GS, Ruiz P, Eicher EM, Pisetsky
DS, et al. Genetic analysis of MRL-lpr mice: relationship of the
Fas apoptosis gene to disease manifestations and renal diseasemodifying loci. J Exp Med 1992;176:1645–56.
Hron JD, Peng SL. Type I interferon protects against murine
lupus. J Immunol 2004;173:2134–42.
Isenberg DA, Katz D, le Page S, Knight B, Tucker L, Maddison P,
et al. Independent analysis of the 16/6 idiotype lupus model: a role
for an environmental factor? J Immunol 1991;147:4172–7.
Leiter EH, Serreze DV, Prochazka M. The genetics and epidemiology of diabetes in NOD mice. Immunol Today 1990;11:147–9.
Bygrave AE, Rose KL, Cortes-Hernandez J, Warren J, Rigby RJ,
Cook HT, et al. Spontaneous autoimmunity in 129 and C57BL/6
mice: implications for autoimmunity described in gene-targeted
mice. PLoS Biol 2004;2:E243.
Bossu P, Neumann D, del Giudice E, Ciaramella A, Gloaguen I,
Fantuzzi G, et al. IL-18 cDNA vaccination protects mice from
spontaneous lupus-like autoimmune disease. Proc Natl Acad Sci U
S A 2003;100:14181–6.
Peng SL. Experimental use of murine lupus models. Methods Mol
Med 2004;102:227–72.
Lauwerys BR, Renauld JC, Houssiau FA. Inhibition of in vitro
immunoglobulin production by IL-12 in murine chronic disease: synergism with IL-18. Eur J Immunol 1998;28:
Izui S, Lambert PH, Fournie GJ, Turler H, Miescher PA. Features
of systemic lupus erythematosus in mice injected with bacterial
lipopolysaccharides: identification of circulating DNA and renal
localization of DNA-anti-DNA complexes. J Exp Med 1977;145:
DOI 10.1002/art.20969
In the article by Hirohata et al published in the December 2004 issue of Arthritis & Rheumatism (pp 3888–3896),
there was an error in the legend to Figure 2B. The first 2 sentences of the Figure 2B legend should read,
“Single-color analysis of the expression of vWF (right histogram). Left histogram shows control staining.”
We regret the error.
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