Role of endogenous and exogenous female sex hormones in arthritis and osteoporosis development in B10.Q-ncf1*/* mice with collagen-induced chronic arthritis.

Abstract

Collagen-induced arthritis (CIA) is an often-used murine model for human rheumatoid arthritis (RA). Earlier studies have shown potent anti-arthritic effects with the female sex hormone estradiol and the selective estrogen receptor modulator (SERM) raloxifene in CIA in DBA/1-mice. B10.Q-ncf1*/*mice are B10.Q mice with a mutated Ncf1 gene. In B10.Q-ncf1*/*mice, CIA develops as a chronic relapsing disease, which more accurately mimics human RA. We investigated the role of endogenous and exogenous sex steroids and raloxifene in the course of this model of chronic arthritis. We also examined whether treatment would prevent the development of inflammation-triggered generalized osteoporosis.
Female B10.Q-ncf1*/*mice were sham-operated or ovariectomized, and CIA was induced. 22 days later, when 30% of the mice had developed arthritis, treatment with raloxifene, estradiol or vehicle was started, and the clinical disease was evaluated continuously. Treatment was continued until day 56 after immunization. At termination of the experiment (day 73), bone mineral density (BMD) was analyzed, paws were collected for histological examination, and sera were analyzed for markers of cartilage turnover and pro-inflammatory cytokines.
Raloxifene and estradiol treatment, as well as endogenous estrogen, decreased the frequency of arthritis, prevented joint destruction and countered generalized osteoporosis. These effects were associated with lower serum levels of the pro-inflammatory cytokine IL-6.
This is the first study to show that raloxifene and estradiol can ameliorate established erosive arthritis and inflammation-triggered osteoporosis in this chronic arthritis model. We propose that treatment with raloxifene could be a beneficial addition to the treatment of postmenopausal RA.

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RESEARCH ARTICLEOpen Access
Role of endogenous and exogenous female sex
hormones in arthritis and osteoporosis
development in B10.Q-ncf1*/*mice with collagen-
induced chronic arthritis
Caroline Jochems1*, Ulrika Islander1, Malin Erlandsson1, Cecilia Engdahl1, Marie Lagerquist1,2, Inger Gjertsson1,
Claes Ohlsson2, Rikard Holmdahl3,4, Hans Carlsten1
Abstract
Background: Collagen-induced arthritis (CIA) is an often-used murine model for human rheumatoid arthritis (RA).
Earlier studies have shown potent anti-arthritic effects with the female sex hormone estradiol and the selective
estrogen receptor modulator (SERM) raloxifene in CIA in DBA/1-mice. B10.Q-ncf1*/*mice are B10.Q mice with a
mutated Ncf1 gene. In B10.Q-ncf1*/*mice, CIA develops as a chronic relapsing disease, which more accurately
mimics human RA. We investigated the role of endogenous and exogenous sex steroids and raloxifene in the
course of this model of chronic arthritis. We also examined whether treatment would prevent the development of
inflammation-triggered generalized osteoporosis.
Methods: Female B10.Q-ncf1*/*mice were sham-operated or ovariectomized, and CIA was induced. 22 days later,
when 30% of the mice had developed arthritis, treatment with raloxifene, estradiol or vehicle was started, and the
clinical disease was evaluated continuously. Treatment was continued until day 56 after immunization. At
termination of the experiment (day 73), bone mineral density (BMD) was analyzed, paws were collected for
histological examination, and sera were analyzed for markers of cartilage turnover and pro-inflammatory cytokines.
Results: Raloxifene and estradiol treatment, as well as endogenous estrogen, decreased the frequency of arthritis,
prevented joint destruction and countered generalized osteoporosis. These effects were associated with lower
serum levels of the pro-inflammatory cytokine IL-6.
Conclusions: This is the first study to show that raloxifene and estradiol can ameliorate established erosive arthritis
and inflammation-triggered osteoporosis in this chronic arthritis model. We propose that treatment with raloxifene
could be a beneficial addition to the treatment of postmenopausal RA.
Background
Rheumatoid arthritis (RA) is a joint destructing autoim-
mune disease affecting 0.5-1% of the adult population
[1,2]. The distribution between men and women is 1:3,
with a peak incidence during menopause and in the
post-partum period [3]. Several studies, including a
population-based case-control study [4], have investi-
gated whether the use of oral contraceptives could have
an impact on the development of RA. Most of these stu-
dies found that current or ever use of oral contracep-
tives do have a protective effect (reviewed in [5]). The
use of hormone replacement therapy (HRT) has been
associated with some beneficial effects on disease activ-
ity [6-9]. For instance, a prospective two-year trial of 88
postmenopausal women with RA found that estrogen-
containing HRT ameliorated clinical disease, retarded
joint destruction, and increased bone mineral density
(BMD) [6]. Estradiol-treatment of collagen-induced
arthritis (CIA) in mice also suppressed disease progres-
sion [10,11], and blocking of the estrogen receptors
* Correspondence: caroline.jochems@rheuma.gu.se
1Department of Rheumatology and Inflammation Research, The Sahlgrenska
Academy at Göteborg University, Göteborg, Sweden
Full list of author information is available at the end of the article
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© 2010 Jochems et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.

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enhanced the disease [12]. CIA is a model of human
RA, and has been widely used to investigate disease
mechanisms and treatments [13]. We have previously
shown potent anti-arthritic effects of the selective estro-
gen receptor modulator (SERM) raloxifene in CIA in
mice, when raloxifene was given as prophylaxis, therapy
or in severe established disease [14,15]. Raloxifene ham-
pered arthritis development, joint destruction and the
development of generalized osteoporosis to the same
degree as estradiol treatment. The rationale for using
raloxifene instead of HRT is that estrogen treatment has
been shown to increase the risk for cancer of the breast
and uterus, as well as stroke, whereas raloxifene treat-
ment does not have these side effects [16-18].
A polymorphism of the Ncf1 gene regulates the sever-
ity of arthritis in rats and mice, and has been shown to
be caused by NADPH oxidase deficiency [19]. This
results in a lower oxidative burst in macrophages,
leading to spontaneous arthritis during the postpartum
period, and to a more severe chronic relapsing collagen-
induced arthritis disease in B10.Q mice with a mutated
Ncf1 gene (B10.Q-ncf1*/*mice) [20,21]. The importance
of reactive oxygen species in human RA was recently
investigated in a Swedish case-control cohort consisting
of 1842 RA cases and 1038 controls [22]. They found a
genetic association between RA and the NADPH-oxi-
dase complex, thus supporting the previous findings
from animal models.
The role of endogenous and exogenous sex hormones
in this chronic arthritis model has not previously been
studied. We also wanted to investigate whether raloxi-
fene would have a beneficial effect in this model. In
addition we evaluated if treatment would prevent arthri-
tis-induced osteoporosis, which is prominent in CIA
[23] and postmenopausal RA [24,25], but has not pre-
viously been reported in arthritic B10.Q-ncf1*/*mice.
Methods
Animals and experimental procedures
The ethical committee for animal experiments at Göte-
borg University approved this study. Female B10.Q-
ncf1*/*mice were generated as previously described [20].
Mice were electronically tagged and kept, 5 to 10 ani-
mals per cage, under standard environmental conditions,
and fed standard laboratory chow and tap water ad
libitum.
Ovariectomy and sham operations were performed at
7-19 weeks of age. Mice of different ages were mixed in
each cage to avoid differences between the treatment
groups. Ovaries were removed through a midline inci-
sion of the skin, and flank incisions of the peritoneum.
The skin incision was closed with metallic clips. Sham-
operated animals had their ovaries exposed but not
removed. Surgery was performed after ketamine
(PfizerAB, Täby, Sweden) and medetomidin (Orion-
Pharma, Espoo, Finland) anesthesia. Carprofen (Orion-
Pharma) was used post-operatively as a painkiller.
Induction and evaluation of arthritis
2 weeks after ovariectomy CIA was induced by immuni-
zation with 100 μg of chicken type II collagen (CII)
(Sigma, St Louis, MO, USA) dissolved in 0.1 M acetic
acid and emulsified with an equal volume of incomplete
Freund’s adjuvant (Sigma) supplemented with 0.5 mg/ml
Mycobacterium tuberculosis (Sigma). A total volume of
100 μl was injected intradermally at the base of the tail.
Mice had already developed arthritis three weeks after
immunization. Arthritis frequency was evaluated con-
tinuously until termination of the experiment. Scoring
was performed in a blinded way without knowledge of
the treatment groups and previous scores, as described
previously [26], scoring 1 to 3 in each paw (maximum
of 12 points per mouse) as follows: 1, swelling or
erythema in one joint; 2, swelling or erythema in
two joints; 3, severe swelling of the entire paw or anky-
losis. The experiment was terminated 73 days after
immunization.
Treatment
Mice were given subcutaneous injections at different
locations 5 days per week of the raloxifene analogue
LY117018 (generous gift from Eli Lilly, Indianapolis, IN,
USA) (60 μg/mouse/day) or 17b-estradiol-3-benzoate
(E2) (Sigma) (1.0 μg/mouse/day) dissolved in Miglyol812
(OmyaPeralta GmbH, Hamburg, Germany). Miglyol812
is a very pure neutral oil from fractionated plant fatty
acids C8and C10. OVX and sham control mice received
Miglyol812 (100 μl/mouse/day). The dosages of raloxi-
fene and E2 have previously been shown to equally well
prevent osteoporosis in mice [27-29]. Treatment with
raloxifene, estradiol or vehicle five days per week was
started therapeutically, 3 weeks after immunization,
when approximately 30% of the mice had developed
arthritis. Treatment was ended on day 56 after immuni-
zation, and the mice were followed until day 73, when
they were sacrificed (Figure 1A).
LY117018 differs from raloxifene at only one site on
the molecule, with a pyrrolidine ring on the basic side
chain instead of a piperidine ring. This small difference
does not affect its biological properties [30].
Tissue collection and histologic examination
At termination of the experiment, mice were anaesthe-
tized for blood withdrawal, and then killed by cervical
dislocation. Sera were individually collected and stored
at -20°C until used. One femur was placed in formal-
dehyde for 24 hours, and then in 70% ethanol, for ana-
lysis of bone mineral density. Paws were fixated in
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paraformaldehyde, decalcified for 30 hours in Parengy’s
decalcification solution (Histolab Products AB, Gothen-
burg, Sweden), and dehydrated over night in a vacuum
infiltrator processor (Tissue-Tek V.I.P., Sakura Finetechni-
cal Co. Ltd., Tokyo, Japan). After being embedded in par-
affin they were sectioned in 4 μm sections on a Leica
RM2255 (Leica Instruments GmbH, Nussloch, Germany).
The sections were deparaffinated and stained in Mayer’s
hematoxylin followed by eosin. The sections were coded
before examination. In sections from each animal, the
proximal parts of all four paws were graded separately on
a scale of 0-4, and the distal part was graded 0-3. This
Frequency of arthritis
20304050
Day
60 7080
0
20
40
60
80
100
BC
****
**
A
0
Immunization
22 56
73
Termination
Treatment
-14
OVX
Sham
Day:
Time
D
Figure 1 Treatment with raloxifene or estradiol hampered arthritis development and joint destruction. Female B10.Q-ncf1*/*mice were
sham-operated or ovariectomized, and immunized with collagen II and Freund’s incomplete adjuvant supplemented with mycobacteria to
induce CIA. Three weeks later treatment was started with raloxifene (60 μg/day; n = 15) (turned triangles), estradiol (1 μg/day; n = 11) (prisms),
or vehicle control (Miglyol812) for sham-operated mice (n = 11; squares) and OVX controls (n = 15; triangles). Treatment was continued until day
56 after immunization, and the experiment was terminated on day 73. A: Diagram of the experimental timeline. OVX, ovariectomy; sham, sham
operation; immunization with collagen II and Freund’s complete adjuvant on day 0. B: Frequency of arthritis. Treatment with raloxifene in OVX
mice delayed the onset and the frequency of arthritis compared to vehicle-treated OVX controls (P < 0.05 for the entire experiment). The
presence of endogenous hormones (sham-operated mice) or estradiol treatment also delayed the onset of arthritis and decreased the frequency
(P < 0.001 and P < 0.001, respectively). There was a significant difference between estradiol treatment and raloxifene treatment (P < 0.001).
Kruskall-Wallis test with post hoc comparison was used. C: Histopathologic destruction scores of paw sections. Scores were evaluated in a
blinded manner, with the proximal part of each paw graded 0-4, and the distal part graded 0-3, yielding a maximum score of 28 per mouse, as
follows: 1 = synovial hypertrophy; 2 = pannus, erosions of cartilage and bone; 3 = severe erosions of cartilage and bone; 4 = complete ankylosis.
The scatter plot shows the scores of individual mice, and lines show the median in each group. Kruskall-Wallis test with post hoc comparison
was used, **P < 0.01. D: Representative images of paw tissue sections, revealing treatment effects on histologic features in each group.
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yielded a maximum histopathological destruction score of
28 points per mouse, assessed as follows: 1 = synovial
hypertrophy, 2 = pannus, discrete erosions of cartilage and
bone, 3 = severe erosions of cartilage and bone, 4 = com-
plete ankylosis.
Assessment of BMD
One femur was subjected to a peripheral quantitative
computed tomography (pQCT) scan with a Stratec
pQCT XCT Research M, software version 5.4B (Nor-
land, Fort Atkinson, WI) at a resolution of 70 μm, as
described previously [31]. Trabecular BMD was deter-
mined with a metaphyseal scan at a point 3% of the
length of the femur from the growth plate. The inner
45% of the area was defined as the trabecular bone com-
partment. Cortical BMD was determined with a mid-
diaphyseal scan.
Identification of serologic markers of cartilage
remodeling
As a marker of cartilage destruction, serum levels of
COMP (cartilage oligomeric matrix protein) were deter-
mined with an Animal COMP® ELISA kit (AnaMar
Medical AB, Uppsala, Sweden).
Serum IL-6 bioassay
A bioassay using the cell line B13.29, subclone B9
(which is dependent on IL-6 for growth) was used to
measure serum levels of IL-6, as described previously
[32,33].
Statistical analysis
For statistical evaluation, the Kruskall-Wallis test fol-
lowed by a post hoc test were used for comparisons
between all groups in each experiment. A P value ≤ 0.05
was considered significant.
Results
Endogenous and exogenous estrogen as well as
raloxifene treatment hampered arthritis in B10.Q-ncf1*/*
mice and protected joints from destruction
To examine the anti-arthritic properties of sex steroids,
ovariectomized female B10.Q-ncf1*/*mice were treated
therapeutically from day 22 until day 56 post immuniza-
tion, with either raloxifene (60 μg/day), estradiol (1.0
μg/day) or vehicle (Miglyol 812). Sham operated con-
trols received Miglyol 812. Arthritis development was
evaluated continuously. Treatment was ended on day 56
to investigate how this would affect the disease.
The cages of mice were randomly divided into the dif-
ferent treatment groups in a blinded way, without knowl-
edge of the arthritic score. As shown in Figure 1B, the
raloxifene treatment group had a frequency of arthritis of
40% at the start of treatment, whereas the other groups
only displayed 20% of mice with arthritis. In spite of this
difference, our results clearly show that raloxifene treat-
ment resulted in a slower onset of arthritis and a lower
frequency of disease, compared to vehicle treated mice (P
< 0.05 for the entire experiment). We also found a signifi-
cantly slower onset of disease in sham-operated mice and
in mice treated with estradiol compared to vehicle con-
trols (P < 0.001 and P < 0.001, respectively), and between
estradiol treatment and raloxifene treatment (P < 0.001).
Histological examination of sections from the paws
revealed severe destruction of the joints in the vehicle trea-
ted controls. In contrast, examination of joints from raloxi-
fene and estradiol treated mice revealed a lower destruction
score (P < 0.01) (Figure 1C and 1D). Similarly, endogenous
estrogen (sham-operated mice) protected the joints from
destruction compared to OVX controls (P < 0.01).
Endogenous and exogenous estrogen, and raloxifene
treatment counteracted osteoporosis in arthritic mice
All mice in this experiment displayed low bone mineral
density (BMD) compared to historic non-arthritic con-
trols [23], where we have previously found the trabecu-
lar and cortical BMD to be 275 and 1270 mg/cm3,
respectively. Vehicle treated OVX mice developed severe
loss of trabecular and cortical BMD compared to sham-
operated mice (P < 0.05 and P < 0.001), indicating a
protective effect of endogenous sex hormones. In con-
trast, treatment with raloxifene and estradiol resulted in
preserved trabecular and cortical BMD, with estradiol
treated mice displaying the highest BMD (P < 0.05 and
P < 0.001, respectively) (Figure 2).
Endogenous and exogenous estrogen, and raloxifene
treatment lowered the serum levels of IL-6
Increased serum IL-6 in arthritis is a marker of the gen-
eral inflammatory disease. The serum levels of IL-6
were significantly lower (P < 0.001) in mice treated with
raloxifene or estradiol, and in sham operated mice, than
in vehicle controls (Figure 3A).
Endogenous estrogen and raloxifene treatment decreased
cartilage resorption
The serum levels of COMP (cartilage oligomeric matrix
protein) are elevated in arthritis due to increased destruc-
tion of joint cartilage. Treatment with raloxifene signifi-
cantly decreased cartilage destruction, as indicated by
lower serum COMP levels, compared to vehicle treated
mice (Figure 3B). Interestingly, sham-operated mice also
had lower levels of COMP, whereas estradiol-treated
mice displayed similar levels as vehicle-treated controls.
Raloxifene did not affect uterine weight
Treatment of the mice was ended on day 56 post immu-
nization, and the experiment was terminated on day 73.
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AB
Trabecular BMD
***
Sham VehicleEstradiol Raloxifene
0
100
200
300
400
500
Cortical BMD
***
ShamVehicleEstradiol Raloxifene
0
1000
1100
1200
1300
*
**
*
***
*
*
C
Sham VehicleEstradiolRaloxifene
mg/cm3
750
0
Figure 2 Treatment with raloxifene or estradiol protected arthritic mice from osteoporosis. Scatter plots showing the trabecular bone
mineral density (BMD) (A) and the cortical BMD (B), measured with peripheral quantitative computer tomography (pQCT) in mice with CIA
treated with raloxifene (60 μg/day), E2 (1 μg/day) or vehicle Miglyol812 (100 μl/day), n = 11-15 in each group. Lines represent medians. Kruskall-
Wallis test with post hoc comparison was used, *P < 0.05, **P < 0.01, ***P < 0.001. C: Representative pQCT scans of cross-sections of the femur,
showing the bone mineral density (BMD). The pictures show one representative mouse in each treatment group. The bar shows the density of
the bone, from 0 (black) to >750 mg/cm3(white).
B
***
A
***
******
Figure 3 Treatment with raloxifene decreased the serum levels of IL-6 and COMP. Scatter plots showing the serum levels of IL-6 (A) and
cartilage oligomeric matrix protein (COMP) (B) in mice with CIA treated with raloxifene (60 μg/day), E2 (1 μg/day) or vehicle Miglyol812 (100 μl/
day). n = 11-15 in each group. Lines represent medians. Kruskall-Wallis test with post hoc comparison was used, *P < 0.05, **P < 0.01,
***P < 0.001.
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As shown in Figure 4, treatment with estradiol resulted
in partly preserved increased uterine weight compared
with OVX mice, even 2.5 weeks after the last injection,
whereas raloxifene did not. This may be due to the ces-
sation of treatment 2.5 weeks before termination of the
experiment. Previous studies have found differential
effects of raloxifene in uterine tissue. We have pre-
viously found a slight proliferative effect in mice treated
for 2.5-3 weeks [28,34], whereas in another study mice
were treated with a higher dose for 5 days, and they
found no proliferative effect [35]. No increase in uterine
weight was found in rats [36-38]. Most importantly,
raloxifene was found to have antiproliferative and proa-
poptotic effects in women [39].
Discussion
This is the first study to evaluate the impact of endo-
genous ovarian hormones, as well as exogenous estradiol
and raloxifene, in the chronic arthritis model of B10.Q-
ncf1*/*mice. This model may more accurately relay the
pathophysiologic process of RA than the widely used
CIA model in DBA/1 mice, since it develops into a
chronic active disease course [20]. We clearly show that
the presence of ovarian hormones protects from devel-
opment of arthritis and joint destruction. Interestingly,
treatment with a physiological dose of estradiol or the
selective estrogen receptor modulator raloxifene was
equally efficient, although the treatment was given to
already arthritic mice from day 22 to day 56 after col-
lagen II immunization. The serum levels of COMP were
significantly decreased in the raloxifene treated mice
and mice with intact endogenous hormones compared
to vehicle controls. This indicates a lower degree of on-
going cartilage destruction. COMP was not decreased in
the estradiol treated mice, although this group also dis-
played significantly less cartilage destruction. This find-
ing is in accordance with the results in a recent study of
CIA in rats demonstrating that estradiol exerts collagen
type II and cartilage protective properties [40].
Women are more prone to develop RA than men, and
the female peak incidence coincides with menopause,
indicating that endogenous female sex hormones like
estradiol have protective properties. Thus, we early pro-
posed that treatment with estradiol would have disease-
retarding effects in postmenopausal RA. The rationale
for investigating the possible impact of raloxifene in this
model is that previous studies have shown ameliorating
effects of hormone replacement therapy containing
estradiol in women with postmenopausal RA, but long-
term therapy is no longer recommended due to the risk
of side effects. We have previously shown, in the murine
CIA model, that raloxifene treatment prophylactically or
as therapy, or even when initiated in established disease,
had a great ameliorating effect on arthritis, as well as on
joint destruction and arthritis-induced osteoporosis
[14,15].
Raloxifene binds with high affinity to estrogen recep-
tor (ER) a, and acts as an estrogen agonist on bone tis-
sue and blood lipids, but as an antagonist on breast and
reproductive tissues [41]. We have recently shown that
signaling through ERa (using propylpyrazoletriol) dra-
matically decreased the frequency and severity of arthri-
tis, and prevented osteoporosis development, in CIA in
DBA/1 mice, whereas signaling through the other estro-
gen receptors (ERb and GPR30) did not affect arthritic
disease or bone loss [42]. Raloxifene acts mainly via
ERa, and its agonistic effects on this receptor were
clearly seen in the current study, with the same anti-
arthritic and anti-osteoporotic effects as estradiol.
We also recently showed that raloxifene activates the
estrogen response element to the same extent as estra-
diol in bone, uterus and thymus, thus indicating that
indeed the effects are mediated via the nuclear estrogen
receptors [34]. Raloxifene has previously been shown to
have a weak proliferative effect on mouse uterus,
whereas estradiol displays a strong proliferative effect
[28]. In the present study we found a lingering increase
in uterus weight in mice treated with estradiol even
though treatment had been halted 17 days before termi-
nation. No increase compared to vehicle treated mice
was seen in the raloxifene treated group at termination,
which may be due to the absence of treatment for the
last 17 days of the experiment.
The serum levels of IL-6 were reduced in mice with
intact endogenous sex hormones, or treated with estra-
diol or raloxifene. IL-6 targeting therapy is now being
used to treat autoimmune diseases, including RA, and
shows promising results with a significant clinical
A
Uterine weight
******
ShamVehicle Estradiol Raloxifene
0
25
50
75
100
**
Figure 4 Treatment with raloxifene did not increase uterine
weight. Scatter plots showing the uterine weights in mice with CIA
treated with raloxifene (60 μg/day), E2 (1 μg/day) or vehicle
Miglyol812 (100 μl/day) from day 22 to day 56 after immunization,
and terminated on day 73, n = 11-15 in each group. Lines represent
medians. Kruskall-Wallis test with post hoc comparison was used,
**P < 0.01, ***P < 0.001.
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response and amelioration of joint damage (reviewed in
[43]). In addition, it was recently shown that blockade
of the IL-6 receptor both in vivo and in vitro
directly affected osteoclast formation, suggesting a direct
bone-sparing effect that is independent of the anti-
inflammatory effects of anti-IL-6 treatment [44]. Thus,
the lowering of serum IL-6 may be one mechanism by
which raloxifene and estradiol exert their anti-osteo-
porotic and anti-arthritic effects.
Conclusions
Based on the results of this study in the chronic arthritis
model and our previous results in the more acute CIA
model, we suggest using raloxifene treatment at the
dose already approved for the treatment of osteoporosis
(60 mg/day) as an addition to the standard treatment of
postmenopausal RA. This could be a beneficial adjuvant
with benefits on both joint damage and osteoporosis,
and without the side effects of hormone replacement
therapy with estradiol. A clinical trial addressing this
issue is planned.
Abbreviations
BMD: bone mineral density; CIA: collagen-induced arthritis; CII: type II
collagen; COMP: cartilage oligomeric matrix protein; E2: estradiol; ELISA:
enzyme-linked immunosorbent assay; ER: estrogen receptor; HRT: hormone
replacement therapy; IL: interleukin; OVX: ovariectomy; pQCT: peripheral
quantitative computed tomography; RA: rheumatoid arthritis; SERM: selective
estrogen receptor modulator.
Acknowledgements
We thank Margareta Rosenkvist, Berit Eriksson, Anette Hansevi, and Maud
Petersson for excellent technical assistance. This study was supported by
grants from the Medical Faculty of Göteborg University (ALF), Göteborg
Medical Society, King GustavV’s 80 years’ foundation, the Sahlgrenska
Foundation, the NovoNordic Foundation, the Börje Dahlin foundation, the
Association against Rheumatism, Reumaforskningsfond Margareta, the
Swedish Research Council the Strategic Science Foundation (SSF) in Sweden,
and EU (Masterswitch HEALTH-F2-2008-223404).
Author details
1Department of Rheumatology and Inflammation Research, The Sahlgrenska
Academy at Göteborg University, Göteborg, Sweden.2Center for Bone
Research at the Sahlgrenska Academy (CBS), Göteborg, Sweden.3Medical
Inflammation Research, MBB, Karolinska Institute, Stockholm, Sweden.
4Medical Inflammation Research, Turku University, Turku, Finland.
Authors’ contributions
HC, RH, CO and IG participated in study design, interpretation of data and
manuscript preparation. UI aided with analysis of data and statistical analysis.
ME, CE and ML aided with acquisition of data. The study was performed
mainly by CJ. All authors read and approved the final manuscript
Competing interests
The authors declare that they have no competing interests.
Received: 18 August 2010 Accepted: 16 December 2010
Published: 16 December 2010
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doi:10.1186/1471-2474-11-284
Cite this article as: Jochems et al.: Role of endogenous and exogenous
female sex hormones in arthritis and osteoporosis development in B10.
Q-ncf1*/*mice with collagen-induced chronic arthritis. BMC
Musculoskeletal Disorders 2010 11:284.
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