Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Open Access
RESEARCH ARTICLE
© 2010 Helmark 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.
Research article
Exercise increases interleukin-10 levels both
intraarticularly and peri-synovially in patients with
knee osteoarthritis: a randomized controlled trial
Ida C Helmark*
1
, Ulla R Mikkelsen
1
, Jens Børglum
2
, Anders Rothe
2
, Marie CH Petersen
1
, Ove Andersen
3
,
Henning Langberg
1
and Michael Kjaer
1
Abstract
Introduction: The microdialysis method was applied to the human knee joint with osteoarthritis (OA) in order to
reveal changes in biochemical markers of cartilage and inflammation, intraarticularly and in the synovium, in response
to a single bout of mechanical joint loading.
Methods: Thirty-one female subjects with OA of the knee were randomized to non-exercise (NEx) or exercise (Ex)
groups. Following acute resistance exercise (25 sets of 10 repetitions at 60% of 1 Repetition Maximum) or none (NEx),
peripheral nerve blocks just below the inguinal ligament were applied and two microdialysis catheters were
positioned in two different compartments, intraarticularly and peri-synovially. The microdialysis catheters were
perfused at a slow rate (2 μl/minute) with a solution of Ringer-acetate and radioactively labelled glucose allowing for
determination of relative recovery (RR) and calculation of interstitial concentrations of inflammatory and cartilage
biomarkers over a three-hour period.
Results: A significant increase of Interleukin (IL) -10 was discovered in both positions of the knee in the Ex group over
the three hours post exercise, whereas IL-10 remained stationary over time in the NEx group. IL-6 and IL-8 displayed
significant increases over time regardless of group and position of the catheter. Cartilage oligomeric matrix protein
(COMP) decreased intraarticularly in the post exercise period in the Ex group compared to the NEx group.
Conclusions: Exercise caused an increase in both intraarticular and peri-synovial concentrations of IL-10 in a group of
human females with knee OA. This suggests a positive effect of exercise on a chondroprotective anti-inflammatory
cytokine response in patients with knee OA and might contribute to explaining the beneficial effect that exercise has
on OA.
Trial registration: NCT01090375.
Introduction
Osteoarthritis (OA) is associated with cartilage erosion
and bony changes as well as with intermittent periods of
synovial membrane inflammation and subsequent release
of biomarkers for inflammation [1]. Excessive loading of
the joint in these patients can lead to a worsening of the
pathology with an enhanced inflammatory response,
joint pain and swelling [2]. On the other hand regular
moderate exercise like strength training, cycling or walk-
ing is known to be advantageous in OA patients with no
sign of deterioration of the inflammatory periods [3-5]. It
is unknown how exercise exerts its beneficial role in OA,
and whether it mainly is accomplished via a stabilisation
of the joints through muscle strength and control, or
whether exercise has a direct effect upon the joint carti-
lage and the synovium. Exercise has been proposed to
positively modulate low-grade inflammation in elderly
patients [6] and has been shown to have a positive effect
on the glycosaminoglycan (GAG) content in cartilage of
subjects at increased risk for OA [7]. It is therefore possi-
ble that acute exercise may induce changes in the intraar-
* Correspondence: ida_caroe@dadlnet.dk
1 Institute of Sports Medicine, Department of Orthopaedic Surger y, Bispebjerg
Hospital and Centre for Healthy Aging, Faculty of Health Sciences, University of
Copenhagen, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark
Full list of author information is available at the end of the article
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 2 of 11
ticular and peri-synovial milieu that encourages anti-
inflammatory activity as well as releases potential chon-
droprotective substances, for example, Interleukin (IL)-
10.
We have previously shown that microdialysis can be
used as a method to investigate, continuously over time,
the peri-synovial interstitial tissue and the joints space in
parallel [8]. Several biomarkers for both cartilage (Aggre-
can, COMP and CTX-II) and inflammation (Interleukins)
have been studied in the circulating blood, the urine and
intraarticularly [9-11]. In the present study the microdial-
ysis method enabled us to investigate biochemical
changes within and around the joint simultaneously in
both the resting state and in a joint that had been sub-
jected to exercise. The aim of the present study was, by
applying the microdialysis technique, to monitor markers
of cartilage breakdown and inflammation intraarticularly
and in the synovium in a group of human females with
knee OA over a period of three hours.
Materials and methods
Subjects
Thirty-one Caucasian women with symptomatic knee
OA and fulfilling ACR (American College of Rheumatol-
ogy) criteria participated after informed consent was
obtained, in the study that was approved by the local Eth-
ics Committee (H-KF-306126) and conducted in compli-
ance with the Helsinki Declaration. Subjects were
physically active and had no regular daily intake of pain
medication or any other anti-inflammatory medication.
None of the subjects had been exposed to any kind of sur-
gery or major acknowledged trauma to the knee that was
examined. Radiographs were taken in order to determine
the Kellgren-Lawrence (K-L) grade and only subjects with
K-L ≥ 1 were included. Subjects were randomized to
either non exercise (NEx) (n = 13) or exercise (Ex) (n =
16). Two women were withdrawn from the study on the
test day due to inadequate effect of the peripheral nerve
blocks; hence, data are given for the 29 subjects who
completed the study. Subjects were instructed to follow
normal daily activities, but to refrain from strenuous
exercise 24 hours prior to the test day. On the test day
they were asked to travel by car or with public transporta-
tion to the hospital.
Exercise protocol
A one-legged knee extension protocol was used. After a
five-minute warm-up on a bicycle subjects were posi-
tioned in a leg-press machine (Techno Gym, Gambettola
(FC), Italy) in an upright position with the knee bent in
90° and then performed a five to seven RM (Repetition
Maximum) test. Hereafter, a working load of approxi-
mately 60% of one RM was applied and subjects com-
pleted 25 sets of 10 repetitions starting every one and a
half minutes. During each set of 10 repetitions the work-
ing leg was extended against a vertical plate, while the
resting leg was positioned on a horizontal plate. If the
subjects experienced intolerable discomfort during the
exercise, adjustment of the weight or seating position was
attempted.
Procedure
On the test day subjects met at either 8.30 (Ex) or 9.30
(NEx) a.m. Subjects in the Ex group completed the exer-
cise protocol and then proceeded with the same schedule
as the NEx group (Figure 1). Blood and urine samples
Figure 1 Test day. Subjects met at either 8.30 a.m. (Ex) or 9.30 a.m. (NEx) according to randomization. Following exercise or none, blood and urine
samples were taken (T1) and regional anaesthesia was applied. Two catheters were hereafter positioned in the suprapatellar recess and in the sub
synovial tissue on the medial side of the knee, respectively. Catheters were removed after three hours of microdialysis. The removal was preceded by
blood and urine samples (T2). Samples of dialysate were collected every 30 minutes. Relative recovery was calculated for every sample and samples
were later pooled (t1 = Sample 1 to 3; t2 = Sample 4 to 6).
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 3 of 11
were taken after approximately 20 to 30 minutes of rest
followed by the application of the ultrasound guided
peripheral nerve blocks within one hour after exercise,
that is, at the latest at 10.30 a.m. The ultrasound guided
peripheral nerve blocks consisted of the so-called proxi-
mal triple block; that is, blocks of the femoral, obturator
(anterior branch) and the lateral femoral cutaneous
nerve. The blocks, applied by an anaesthesiologist, pro-
vided consistent effective anaesthesia of the knee for the
time required for insertion of the catheters. The effect of
the triple block gradually disappeared during the
microdialysis period. The microdialysis catheters were
positioned intraarticularly and close to the synovial tissue
but extraarticularly, respectively (Figure 2 for schematic
illustration). The positioning procedure has previously
been tested in a pilot study on patients undergoing
planned arthroscopy of the knee [8]. Both microdialysis
catheters were connected to the microdialysis pump and
perfused at a perfusion rate of 2 μl/minute. Samples were
collected every 30 minutes and weighed before storage at
-80°C.
Principles of microdialysis
The custom-made microdialysis catheter consists of an
inlet and an outlet tube connected by a 30 mm long mem-
brane with a pore size of 3,000 kDa and a diameter of 0.4
mm [12]. The inlet tube is connected to a precision pump
(2 μl/min) and hereby a state of near-equilibrium is
reached around the membrane. The dialysate collected
from the outlet tube contains molecules from the region
of interest in which the catheter was positioned, making
it possible to calculate the interstitial concentration of
different molecules. In the present study we perfused the
catheters with a Ringer solution containing radioactive
labelled glucose (D-(3-3H)glucose) in order to determine
Figure 2 Schematic illustration of the positioning of the catheters in the knee joint with osteoarthritis. The intraarticular catheter is placed in
the suprapatellar recess and the peri-synovial catheter in the medial part of the knee capsule. A precision pump perfuses the catheters at a selected
rate of 2 μl/min.
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 4 of 11
the relative recovery (RR), a measure of the exchange rate
of substances over the membrane. Relative recovery was
calculated from the following equation:
Where Pdpm and Ddpm refers to the activities (disintegra-
tions per minute) of the labelled glucose for the perfusate
and the dialysate respectively. The interstitial concentra-
tions are calculated using the internal reference calibra-
tion method equalling (Cd - Cp)/RR, where Cd is dialysate
concentration and Cp is perfusate concentration [13].
Samples
Blood and urine samples were collected in a standardized
manner at the same time point in the morning (T1) and
just before removal of the microdialysis catheters in the
afternoon (T2). Blood samples were taken from the ante-
cubital vein after a resting period of 20 to 30 minutes.
Samples were centrifuged at 3,880 rpm and 4°C for 10
minutes and immediately after frozen at first -20°C and
then -80°C until analysis. Microdialysis samples were col-
lected every 30 minutes, weighed and 2 × 3 μl were taken
from each sample in order to determine the activity (in
duplicate) of the labelled glucose before samples were
frozen at -80°C.
Analysis
Samples were analyzed for COMP, Aggrecan, CTX-II,
Interleukin (IL) -6, IL-8, IL-10 and Tumor Necrosis Fac-
tor (TNF)-α. Concentrations were determined with com-
mercially available assays (COMP® ELISA, AnaMar
Medical AB, Sweden; Total Aggrecan for Culture® ELISA;
Urine and Serum Preclinical Cartilaps® ELISA, IDS Nor-
dic, Denmark; Milliplex®MAP, Millipore, Billerica, Massa-
chusetts, USA). Samples were run in duplicate for all of
the cartilage markers; inflammatory markers were run in
duplicate when the amount of dialysate allowed it
(approximately one third of the samples). COMP was
determined in microdialysate and serum; Aggrecan in
microdialysate, serum and urine; CTX-II in urine and
inflammatory markers in microdialysate. Urinary creati-
nine was measured by a routine chemistry method and
used for the calculation of creatinine-corrected urinary
CTX-II and Aggrecan concentrations. Due to the small
amount of microdialysate and low concentration of carti-
lage biomarkers it was not possible to perform analysis
for every microdialysis sample, instead Sample 1 to 3
(denominated t1) and Sample 4 to 6 (denominated t2)
were pooled and analyzed together.
Statistics
Data on subjects' characteristics are given as mean ± SD
and Students t-test was used to compare between groups.
A one-way ANOVA was used to determine if there were
differences in RR over the three hours of microdialysis.
Results on biomarkers and cytokines are illustrated in fig-
ures with a before/after value and a connecting line.
Comparison was done using non-parametric statistics
due to the non normal distribution of data. Wilcoxon
matched pair test for comparison within a group, and
Mann Whitney test for comparison between groups.
Level of significance was set at a two-tailed P-value of
0.05.
Results
Subjects
Twenty-nine subjects completed the test day, the Ex
group with an average work load of 61 ± 7% of oneRM
(mean ± SD). No differences were found between the
non-exercise (NEx) and exercise (Ex) groups with regards
to age, BMI, K-L grade or pain (Table 1). The KOOS
questionnaire, which was filled in on the test day, did not
show any differences between the two groups in any of
the measured parameters (Pain, Symptom, Function in
daily living, Function in sport and recreation and knee
related Quality of life). Subjects completed the exercise
protocol without reporting any unusual discomfort (pain
or swelling) of the knee during the exercise or in the
hours/days following the exercise. (A telephone interview
was conducted two days after the test day).
Method
Relative recovery was calculated for each of the samples
recovered from the 29 subjects; however, in five subjects
no peri-synovial catheters were inserted due to technical
difficulties from relative larger volumes of adipose tissue
in some subjects. The average RR from the intraarticular
and peri-synovial catheters was unaffected by exercise,
RR P D P
dpm dpm dpm
=− /
Table 1: Demographics of the subjects
Age (years) BMI (kg/m2)K-L grade Pain
NEx (N = 13) 67 ± 7 25.1 ± 2.6 2.5 ± 0.8 69 ± 16
Ex (N = 16) 66 ± 6 26.4 ± 2.8 2.3 ± 0.9 64 ± 13
Data are presented as mean ± SD, no significant differences were found between groups. Pain was registered using the KOOS questionnaire
with 100 indicating no symptoms and 0 indicating extreme symptoms. (BMI: Body Mass Index, K-L: Kellgren-Lawrence).
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 5 of 11
that is, there was no difference between the NEx and Ex
groups, but in the NEx group alone there was a signifi-
cant difference in RR between the two compartments (P
< 0.05, results not shown). No difference in RR was found
over the course of time, that is, from Sample 1 to Sample
6, overall or in NEx and Ex groups respectively (one-way
ANOVA, P > 0.05).
Inflammatory markers
The IL-10 concentration showed significant increases in
both the peri-synovial and the intraarticular compart-
ments (P < 0.05) (Figure 3). The rise in IL-10 concentra-
tions was found only in the Ex group whereas the NEx
group maintained a stationary level. A highly significant
increase was found over time for IL-6 and IL-8 in both
positions regardless of exercise. Intraarticular TNF-α lev-
els were significantly elevated in both groups, but for the
peri-synovial levels an increase was found only in the Ex
group. Due to levels below the minimum detectable con-
centration are only few results available for IL-8 concen-
trations peri-synovially. No differences were found
between groups at t1 for either of the cytokines.
Cartilage markers
Serum measurements showed a significant decrease in
COMP and Aggrecan concentrations over time in both
groups, but no difference was found between groups at
T1, where the Ex group had already completed the exer-
cise protocol (Figure 4). The intraarticular microdialysate
concentration of COMP decreased in the Ex group from
t1 to t2, whereas the level in the NEx group was station-
ary from t1 to t2 (Figure 5). Aggrecan concentration
decreased in both groups from t1 to t2 intraarticularly.
No difference was found between groups at t1 for neither
COMP nor Aggrecan (Figure 5). Aggrecan did similarly
decrease significantly in both groups over time in the
peri-synovial compartment, whereas COMP did not
change from t1 to t2 in either group (Figure 5). Due to
values below the detection limit only five sets of paired
values were obtained in the Ex group. The urinary con-
centration of Aggrecan was significantly elevated in the
Ex group at T1 compared to T2. After three hours of
microdialysis the level returned to the level of the NEx
group (Figure 6).
Discussion
The microdialysis method was applied to a group of
human females with OA of the knee in order to obtain
information about the effect of a single bout of mechani-
cal loading on cartilage biomarkers and cytokines both
inside the joint as well as in the synovium over a period of
three hours. The present study demonstrates that the
anti-inflammatory cytokine, IL-10, increased signifi-
cantly over time post exercise in the Ex group in both
compartments, but not in the NEx group, indicating that
the increase observed in the Ex group could be ascribed
to exercise (Figure 3). Most previous studies on IL-10 and
OA have been conducted on animals or ex vivo, and only
a few investigators have also measured the concentration
of IL-10 in synovial fluid in humans with OA, revealing
concentrations in accordance with the present findings
[14,15] or in some cases showing non detectable concen-
trations [16,17]. To our knowledge, the intraarticular and
the peri-synovial concentration responses to exercise
have never been investigated in OA previously. It is of
interest that IL-10 responds positively to mechanical joint
loading in this patient group, as IL-10 has been found to
display chondroprotective properties by antagonizing
important steps in the suggested pathogenesis of OA,
such as suppressing the release of inflammatory media-
tors by macrophages and the activation of synoviocytes
and chondrocytes [18,19]. The previously mentioned
study by Fraser et al [14] found that patients with early
psoriatic arthritis and early rheumatoid arthritis have
higher levels of IL-10 compared to patients in later stages
of the disease. It appears that development of the disease
leads to an impaired capacity to suppress the release of
inflammatory mediators and thus a decreased immuno-
response beyond a certain point in the disease course.
Taking into account the present data, this would argue in
favour of stimulating the joints of patients with early OA,
or patients at high risk of developing OA, with exercise,
as this would result in a release of IL-10, a response that
potentially could have beneficial effects upon the control
of the immune response. The general influence of exer-
cise on IL-10 has not been investigated formerly in
human joint aspirates of synovial fluid and previous stud-
ies on serum levels show some inconsistency [20-23].
One study has, in support of our results, demonstrated
that higher levels of regular physical activity are associ-
ated with increased levels of IL-10 in the blood of healthy
older males, whereas studies on young, moderately and
well-trained males in different training sessions have
shown both increases as well as a decrease in serum IL-10
concentrations. Increased production of anti-inflamma-
tory cytokines during exercise can possibly restrict the
production of pro-inflammatory cytokines such as IL-6,
IL-8 and TNF-α. In vitro studies suggest that IL-6 act as a
negative regulator of chondrocyte proliferation and artic-
ular cartilage metabolism [24] and that IL-8 possibly act
as a modulator of both IL-6 and TNF-α as well as a
chemotactic agent for neutrophils [25]. Hence, these
cytokines play an important role in the low-inflammatory
response of OA. In our study we determined highly sig-
nificant increases in IL-6 and IL-8 concentrations from
the first hour and a half of sampling to the second hour
and a half of sampling; regardless of exercise and position
of the catheter (Figure 3). Our levels reached medians of
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 6 of 11
Figure 3 Concentrations of IL-6, IL-8, IL-10 and TNF-α. Intraarticular (left panel) and peri-synovial (right panel) concentrations in the NEx and Ex
gro ups at T1 and T 2. E ach p oin t rep rese nts a mea n (wh en r un in dupl ica te) o f the mea sure d val ues and e ach c onn ecti ng li ne r epre sents a subject with
before/after values. IL-10 increased significantly in the Ex group in both compartments (*P < 0.05), but remained stationary in the NEx group. Signifi-
cant increases regardless of exercise are seen for IL-6 and IL-8 in both positions and also for TNF-α intraarticularly (*P < 0.05), whereas TNF-α increased
peri-synovially in the Ex group but not in the Ex group. (i.a., intraarticular; syn, peri-synovial).
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 7 of 11
approximately 600 pg/ml and 5,000 pg/ml for each of the
sampling periods irrespective of the position of the cathe-
ter, which contrasts with the findings of other investiga-
tors, who discovered levels of IL-6 and IL-8 in synovial
fluid obtained by direct joint puncture of approximately
50 to 200 pg/ml [11,26,27]. A major trauma to the knee
such as a tear of the anterior cruciate ligament has been
found to result in IL-6 levels above 20,000 pg/ml within
the first couple of days [28], and as the concentrations in
the present study increased over time our findings could
indicate that the insertion of the catheters per se induced
a production of these cytokines due to the tissue injury.
TNF-α concentrations show a pattern similar to IL-6 and
IL-8, but for the peri-synovial level an increase was found
only in the Ex group. The overall intraarticular concen-
trations of TNF-α at t1 in our study are somewhat below
what has previously been reported [14,27,29]. We have no
obvious explanation for this finding, but it could be spec-
ulated that the known suppressive effect of IL-10 on
TNF-α [18,30] could have contributed to the present
findings.
Many biomarkers of cartilage measured in blood are
known to present a circadian variation with concentra-
tions being lower during the night and higher during day-
time [9,31], most likely due to an effect of the tissue
resting. In the present study we have confirmed this rest-
ing effect as serum concentrations of COMP and Aggre-
can decrease over the course of the test day (Figure 4).
Other studies have detected a temporary increase in
serum COMP following exercise [32,33], which was not
the case in our study, maybe due to the exercise protocol
not being strenuous enough to induce systemic changes.
We have, however, demonstrated for the first time that
unloading of the joints for three hours results in an
immediately measurable decrease in Aggrecan inside a
single joint as well as in the synovium (Figure 5) despite
previous physical activity. This is in agreement with the
suggestion that Aggrecan is one of the first fragments to
be released during cartilage breakdown. A high metabo-
lism of Aggrecan would lead to an increased excretion
through the urine, and it could then be expected that a
higher urinary concentration would be seen in the Ex
group, reflecting a faster turnover. The difference
between the two groups at that point (T1, where the Ex
group had already performed the exercise protocol as
compared to the NEx group) did, however, not reach sta-
tistical significance. Instead a significant difference was
found within the Ex group, indicating a faster reversion to
baseline level (Figure 6). The concentration of CTX-II, a
degradation product from collagen II, was not affected by
a single bout of exercise in our subjects, and it is likely
that the systemic measurement was too crude and insen-
sitive to be able to detect any contribution from a single
joint. It probably requires long term adaptation to loading
to change the CTX-II level which has been demonstrated
by O'Kane et al. in elite athletes performing different
kinds of sports [34] and in OA patients followed for years
[35]. Interstitial concentration of COMP did not reveal
any changes in the NEx group in either of the compart-
ments, but in the Ex group we found a significant
decrease intraarticularly but not peri-synovially (Figure
5). A plausible reason for the intraarticular decrease
could be the increased blood-flow and hydrostatic pres-
sure following exercise, which could lead to a faster elimi-
nation of the COMP molecules in the Ex group. The
turnover of cartilage is very slow with an estimated half
Figure 4 Serum concentrat ions of COM P and Aggre can in the N Ex and Ex gr oups at T1 an d T2. Each point represents a mean of the measured
values and each connecting line represents a subject with before/after values. A significant decrease over time was found in both groups for both
markers, regardless of exercise (*P < 0.05).
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 8 of 11
life of collagen II of more than 100 years and for Aggrecan
of 3 to 24 years [36,37]. It is therefore not realistic that a
single bout of exercise should have caused a molecular
rearrangement of the cartilage; hence, the measured mol-
ecules must have been present in the joint space or very
close to the cartilage surface during the exercise.
The microdialysis method used in the present study has
been applied to a variety of human tissues including
brain, adipose tissue and peritendinous tissue [38-40] and
is generally considered a minimally invasive procedure
compared to other tissue sampling techniques. It must be
acknowledged, though, that the microdialysis method
still causes tissue injury during the insertion of the cathe-
ters which by itself can generate an inflammatory
response as shown by Langberg et al in peritendinous tis-
sue and by Clough et al. [41] in relation to skin wounding
and allergen-induced inflammation. A sharp rise in IL-6
and IL-8 concentrations was found in the area with
inflammation, although not to the same extent for IL-6 as
in the present study. Importantly, Clough et al [41] also
found an increase at a 1 cm distance from the insertion
site, which indicates that the increased production of
cytokines found in our study may be a result of a larger
involvement of the already inflamed tissue next to the
insertion site. Another important issue regarding the
microdialysis method is the choice of tracer for determi-
nation of relative recovery. We used radioactively labelled
glucose, which is a small molecule of only 0.18 kDa com-
pared to Aggrecan and COMP (exceeding 500 kDa), and
the chosen cytokines with a molecular weight of 11.1 to
25.6 kDa. This probably leads to an underestimation of
the true concentrations (due to an overestimated RR)
with regards to the cartilage markers. In addition, larger
molecules such as markers of cartilage turn-over, do not
move readily, which creates a possible risk of drainage
from the area around the membrane. This must be con-
sidered since the concentrations of Aggrecan and COMP
in our study are far from what joint puncture has shown
in other studies on similar patients [42-44]. However,
even taking these limitations into consideration, it is
Figure 5 Intraarticular (top row) and peri-synovial (bottom row) concentrations of COMP and Aggrecan. Each point represents a mean of the
measured values and each connecting line represents a subject with before/after values. COMP remained stationary in the NEx group in both com-
partments and in the Ex group peri-synovially over time, but decreased in the Ex group intraarticularly, whereas Aggrecan concentrations decreased
significantly from T1 to T2 in both positions regardless of exercise (*P < 0.05).
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 9 of 11
important to note that procedures were identical for Ex
and NEx groups, and this should not influence the detec-
tion of potential differences between groups.
Because of the specific use of anaesthetic method in
this study and due to the risk of infection it was not con-
sidered pertinent to have catheters inserted before and
again after exercise. Even with a block of only sensory
nerves the risk of damage to the catheters during exercise
would be too high, so we were constrained to look at two
different groups and compare these. We believe the two
groups are very homogenous as the KOOS score and
other demographics showed no differences between
groups. The presented results are valid for at selected
group of female subjects, all with a relatively low Body
Mass Index compared to other OA patients (because the
insertion of the peri-synovial catheter would otherwise
be complicated by penetrating too much adipose tissue)
and with no history of other inflammatory diseases or
regular intake of anti-inflammatory drugs.
With the limited conservative treatment options for
OA patients it is of great importance to uncover the bene-
fits of different kinds of exercise in order to provide a
possibility of self-management. It could be speculated if
specific groups of knee OA patients with no contraindi-
cations should be encouraged to perform more loadbear-
ing activities to further improve the effect of exercise.
Conclusions
The present study demonstrates that it is possible to eval-
uate the effect of a single bout of exercise on cartilage and
inflammatory markers in a group of female subjects with
OA of the knee, over time and simultaneously in two dif-
ferent compartments of the knee, using the microdialysis
method. We discovered a significant increase of the
chondroprotective IL-10 only in the group that per-
formed exercise compared to the non-exercising group
intraarticularly as well as peri-synovially. This might con-
tribute to explain the beneficial effect that exercise has on
patients with knee OA.
Abbreviations
ACR: American College of Rheumatology ; COMP: Cartilage Oligomeric Matrix
Protein; CTX-II: Telopeptide; Ex: Exercise group; GAG: glycosaminoglycan; IL:
Interleukin; K-L: Ke llgren-Lawrence; NEx: Non Exercise group; OA: Osteoar thritis;
RM: Repetition Maximum; RR: Relative Recovery; TNF-α: Tumor Necrosis Factor
α.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
ICH designed the study, led and performed the experimental procedure dur-
ing test days, gathered and processed the data, and drafted the manuscript.
URM participated in the study design and coordination and helped to draft the
manuscript. JB and AR provided the anaesthesiological assistance. MCHP per-
formed the immunoassays of the cartilage markers. OA contributed with the
analysis of cytokines. HL and MK participated in the design of the study and
participated in its design and coordination, and helped to draft the manu-
script. All authors have read and approved the final manuscript.
Acknowledgements
We thank Lab Technician Diana Klüver at Hvidovre Hospital, Clinical Research
Centre for technical assistance with the analysis of cytokines.
Funding sources: Danish Rheumatism Association, Danish Ministry of Health,
Internal Affairs, Danish National Research Council, Danish Medical Research
Council.
Author Details
1Institute of Sports Medicine, Department of Orthopaedic Surgery, Bispebjerg
Hospital and Centre for Healthy Aging, Faculty of Health Sciences, University of
Copenhagen, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark,
2Department of Anaesthesiology and Intensive Care Medicine, Bispebjerg
Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark and 3Clinical
Research Centre and Dept. of Infectious Diseases, Hvidovre Hospital, Kettegård
Allé 30, 2650 Hvidovre, Denmark
Figure 6 Creatinine-corrected urinary concentrations of Aggrecan and CTX-II in NEx and Ex groups at T1 and T2. Each point represents a
mean of the measured values and each connecting line represents a subject with before/after values. The Ex group had a significantly higher level of
Aggrecan in the urine immediately after exercise compared to the values after three hours of microdialysis (rest), whereas the NEx group showed no
significant difference between T1 and T2 (*P < 0.05). CTX-II displayed no changes over time.
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 10 of 11
References
1. Benito MJ, Veale DJ, FitzGerald O, van den Berg WB, Bresnihan B: Synovial
tissue inflammation in early and late osteoarthritis. A nn Rheum Dis
2005, 64:1263-1267.
2. Rogind H, Bibow-Nielsen B, Jensen B, Moller HC, Frimodt-Moller H, Bliddal
H: The effects of a physical training program on patients with
osteoarthritis of the knees. Arch Phys Med Rehabil 1998, 79:1421-1427.
3. van Baar ME, Dekker J, Oostendorp RA, Bijl D, Voorn TB, Lemmens JA,
Bijlsma JW: The effectiveness of exercise therapy in patients with
osteoarthritis of the hip or k nee: a randomized clinical trial. J
Rheumatol 1998, 25:2432-2439.
4. Ettinger WH Jr, Burns R, Messier SP, Applegate W, Rejeski WJ, Morgan T,
Shumaker S, Berry MJ, O'Toole M, Monu J, Craven T: A randomized trial
comparing aerobic exercise and resistance exercise with a health
education program in older adults with knee osteoarthritis. The Fit ness
Arthritis and Seniors Trial (FAST). JAMA 1997, 277:25-31.
5. Fransen M, Crosbie J, Edmonds J: Physical therapy is effective for
patients with osteoarthritis of the knee: a randomized controlled
clinical trial. J Rheumatol 2001, 28:156-164.
6. Pedersen BK, Bruunsgaard H: Possible beneficial role of exercise in
modulating low-grade inflammation in the elderly. S cand J Med Sci
Sports 2003, 13:56-62.
7. Roos EM, Dahlberg L: Positive effects of moderate exercise on
glycosaminoglycan content in knee cartilage: a four-month,
randomized, controlled trial in patients at risk of osteoar thritis. Arthritis
Rheum 2005, 52:3507-3514.
8. Helmark IC, Mikkelsen UR, Krogsgaard MR, Belhage B, Petersen MC,
Langberg H, Kjaer M: Early osteoarthritis and microdialysis: A novel in
vivo approach for measurements of biochemical markers in the
perisynovium and intraarticularly. Knee Surg Spor ts Traumatol Arthrosc
2010 in press.
9. Kong SY, Stabler TV, Criscione LG, Elliott AL, Jordan JM, Kraus VB: Diurnal
variation of serum and urine biomarkers in patients with radiographic
knee osteoarthritis. Arthritis Rheum 2006, 54:2496-2504.
10. Dahlberg L, Friden T, Roos H, Lark MW, Lohmander LS: A longitudinal
study of cartilage matrix metabolism in patients with cruciate ligament
rupture--synovial fluid concentrations of aggrecan fragments,
stromelysin-1 and tissue inhibitor of metalloproteinase -1. Br J
Rheumatol 1994, 33:1107-1111.
11. Doss F, Menard J, Hauschild M, Kreutzer HJ, Mittlmei er T, Muller-Steinhardt
M, Müller B: Elevated IL-6 levels in the synovial fluid of osteoarthritis
patients stem from plasma cells. Scand J Rheumatol 2007, 36:136-139.
12. Langberg H, Skovgaard D, Petersen LJ, Bulow J, Kjar M: Type I collagen
synthesis and degradation in peritendinous tissue after exercise
determined by microdialysis in humans. J Physiol 1999, 521:299-306.
13. Scheller D, Kolb J: The internal reference technique in microdialysis: a
practical approach to monitoring dialysis efficiency and to calculating
tissue concentration from dialysate samples. J Neurosci Methods 1991,
40:31-38.
14. Fraser A, Fearon U, Billinghurst RC, Ionescu M, Reece R, Barwick T, Emery P,
Poole AR, Veale DJ: Turnover of type II collagen and aggrecan in
cartilage matrix at the onset of inflammatory arthritis in humans:
relationship to mediators of systemic and local inflammation. Arthritis
Rheum 2003, 48:3085-3095.
15. Loria MP, Dambra P, Moretti B, Patella V, Capuzzimati L, Cavallo E, Nettis E,
Pesce V, Dell'Osso A, Simone C, Tursi A: Role of cytokines in gonarthrosis
and knee prosthesis aseptic loosening. J Orthop Sci 2004, 9:274-279.
16. Partsch G, Wagner E, Leeb BF, Broll H, Dunky A, Smolen JS: T cell derived
cytokines in psoriatic arthritis synovial fluids. Ann Rheum Dis 1998,
57:691-693.
17. Ribbens C, Andre B, Kaye O, Kaiser MJ, Bonnet V, de Groote D,
Franchimont N, Malaise MG: Increased synovial fluid levels of
interleukin-12, sCD25 and sTNF-RII/sTNF-RI ratio delineate a cytokine
pattern characteristic of immune arthropathies. Eur Cytokine Netw
2000, 11:669-676.
18. Hart PH, Ahern MJ, Smith MD, Finlay-Jones JJ: Comparison of the
suppressive effects of interleukin-10 and interleuk in-4 on synovial fluid
macrophages and blood monocytes from patients with inflammatory
arthritis. Immunology 1995, 84:536-542.
19. Schulze-Tanzil G, Zreiqat H, Sabat R, Kohl B, Halder A, Muller RD, John T:
Interleukin-10 and Articular Cartilage: Experimental Therapeutical
Approaches in Cartilage Disorders. Curr Gene Ther 2009 in press.
20. Brenner IK, Natale VM, Vasiliou P, Moldoveanu AI, Shek PN, Shephard RJ:
Impact of three different types of exercise on components of the
inflammatory response. Eur J Appl Physiol O ccup Physiol 1999,
80:452-460.
21. Peake JM, Suzuki K, Hordern M, Wilson G, Nosaka K, Coombes JS: Plasma
cytokine changes in relation to exercise intensity and muscle damage.
Eur J Appl Physiol 2005, 95:514-521.
22. Izquierdo M, Ibanez J, Calbet JA, Navarro-Amezqueta I, Gonzalez-Izal M,
Idoate F, Häkkinen K, Kraemer WJ, Palacios-Sarrasqueta M, Almar M,
Gorostiaga EM: Cytokine and hormone responses to resistance training.
Eur J Appl Physiol 2009, 107:397-409.
23. Jankord R, Jemiolo B: Influence of physical activity on serum IL-6 and IL-
10 levels in healthy older men. Med Sci Sports Exerc 2004, 36:960-964.
24. Jikko A, Wakisaka T, Iwamoto M, H iranuma H, Kato Y, Maeda T, Fujishita M,
Fuchihata H: Effects of interleukin-6 on proliferation and proteoglycan
metabolism in articular chondrocyte cultures. Cell Biol Int 1998,
22:615-621.
25. Yu CL, Sun KH, Shei SC, Tsai CY, Tsai ST, Wang JC, Liao TS, Lin WM, Chen HL,
Yu HS, et al.: Interleukin 8 modulates interleukin-1 beta, interleukin-6
and tumor necrosis factor-alpha release from normal human
mononuclear cells. Immunopharmacology 1994, 27:207-214.
26. Bianchi M, Broggini M, Balzarini P, Baratelli E, Ferrario P, Panerai AE,
Sacerdote P: Effects of tramadol on synovial fluid concentrations of
substance P and interleukin-6 in patients with knee osteoarthritis:
comparison with paracetamol. Int Immunopharmacol 2003,
3:1901-1908.
27. Sezgin M, Demirel AC, Karaca C, Ortancil O, Ulkar GB, Kanik A, Cakçi A:
Does hyaluronan affect inflammatory cytokines in knee osteoar thritis?
Rheumatol Int 2005, 25:264-269.
28. Irie K, Uchiyama E, Iwaso H: Intraarticular inflammatory cytokines in
acute anterior cruciate ligament injured knee. Knee 2003, 10:93-96.
29. Scanzello CR, Umoh E, Pessler F, Diaz-Torne C, Miles T, Dicarlo E, Potter HG,
Mandl L, Marx R, Rodeo S, Goldring SR, Crow MK: Local cytokine profiles
in knee osteoarthritis: elevated synovial fluid interleukin-15
differentiates early from end-stage disease. Osteoarthritis Cartilage
2009, 17:1040-1048.
30. Alaaeddine N, Di Battista JA, Pelletier JP, Kiansa K, Cloutier JM, Martel-
Pelletier J: Inhibition of tumor necrosis factor alpha-induced
prostaglandin E2 production by the antiinflammator y cytokines
interleukin-4, interleukin-10, and interleuk in-13 in osteoarthritic
synovial fibroblasts: distinct targeting in the signaling pathways.
Arthritis Rheum 1999, 42:710-718.
31. Andersson ML, Petersson IF, Karlsson KE, Jonsson EN, Mansson B,
Heinegard D, Saxne T: Diurnal variation in serum levels of cartilage
oligomeric matrix protein in patients with knee osteoar thritis or
rheumatoid arthritis. Ann Rheum Dis 2006, 65:1490-1494.
32. Mundermann A, Dyrby CO, Andriacchi TP, King KB: Serum concentration
of cartilage oligomeric matrix protein (COMP) is sensitive to
physiological cyclic loading in healthy adults. Osteoarthritis Cartilage
2005, 13:34-38.
33. Andersson ML, Thorstensson CA, Roos EM, Petersson IF, Heinegard D,
Saxne T: Serum levels of cartilage oligomeric matrix protein (COMP)
increase temporarily after physical exercise in patients with knee
osteoarthritis. BMC Musculoskelet Disord 2006, 7:98.
34. O'Kane JW, Hutchinson E, Atley LM, Eyre DR: Sport-related differences in
biomarkers of bone resorption and cartilage degradation in endurance
athletes. Osteoarthritis Cartilage 2006, 14:71-76.
35. Reijman M, Hazes JM, Bierma-Zeinstra SM, Koes BW, Christgau S,
Christiansen C, Uitterlinden AG, Pols HA: A new marker for osteoarthritis:
cross-sectional and longitudinal approach. Arthritis Rheum 2004,
50:2471-2478.
36. Verzijl N, Degroot J, Thorpe SR, Bank RA, Shaw JN, Lyons TJ, Bijlsma JW,
Lafeber FP, Baynes JW, TeKoppele JM: Effect of collagen turnover on the
accumulation of advanced glycation end products. J Biol Chem 2000,
275:39027-39031.
37. Maroudas A, Bayliss MT, Uchitel-Kaushansky N, Schneiderman R, Gilav E:
Aggrecan turnover in human articular cartilage: use of aspartic acid
racemization as a marker of molecular age. Arch Biochem Biophys 1998,
350:61-71.
Received: 18 March 2010 Revised: 3 June 2010
Accepted: 1 July 2010 Published: 1 July 2010
This article is available from: http://arthritis-research.com/content/12/4/R126© 2010 Helmark 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.Arthritis Research & Therapy 2010, 12:R126
Helmark et al. Arthritis Research & Therapy 2010, 12:R126
http://arthritis-research.com/content/12/4/R126
Page 11 of 11
38. Ungerstedt U, Hallstrom A: In vivo microdialysis--a new approach to the
analysis of neurotransmitters in the brain. Life Sci 1987, 41:861-864.
39. Arner P, Bolinder J, Eliasson A, Lundin A, Ungerstedt U: Microdialysis of
adipose tissue and blood for in vivo lipolysis studies. Am J Physiol 1988,
255:E737-E742.
40. Langberg H, Olesen JL, Gemmer C, Kjaer M: Substantial elevation of
interleukin-6 concentration in peritendinous tissue, in contrast to
muscle, following prolonged exercise in humans. J Physiol 2002,
542:985-990.
41. Clough GF, Jackson CL, Lee JJ, Jamal SC, Church MK: What can
microdialysis tell us about the temporal and spatial generation of
cytokines in allergen-induced responses in human skin in vivo? J Invest
Dermatol 2007, 127:2799-2806.
42. Momohara S, Okada N, Ikari K, Mizuno S, Okamoto H: Dermatan sulfate in
the synovial fluid of patients with knee osteoarthritis. Mod Rheumatol
2007, 17:301-305.
43. Lohmander LS, Saxne T, Heinegard DK: Release of cartilage oligomeric
matrix protein (COMP) into joint fluid after knee injury and in
osteoarthritis. Ann Rheum Dis 1994, 53:8-13.
44. Herrero-Beaumont G, Guerrero R, Sanchez-Pernaute O, Acebes C, Palacios
I, Mas S, Rodriguez I, Egido J, Vivanco F: Cartilage and bone biological
markers in the synovial fluid of osteoarthritic patients af ter hyaluronan
injections in the knee. Clin Chim Acta 2001, 308:107-115.
doi: 10.1186/ar3064
Cite this article as: Helmark et al., Exercise increases interleukin-10 levels
both intraarticularly and per i-synovially in patients with knee osteoarthritis: a
randomized controlled trial Arthritis Research & Therapy 2010, 12:R126
