Antioxidant Enzymes and Oxidative Stress Markers in the Blood of Patients
with Metal-on-Metal Total Hip Arthroplasty
1,2
Tkaczyk C, 2Petit A, 2Mwale F, 2Antoniou J, 2Zukor DJ, 1Tabrizian M, +2Huk OL
Department of Biomedical Engineering, Faculty of Medicine, McGill University, Montreal, QC, Canada
2
Division of Orthopaedic Surgery, McGill University and Lady Davis Institute for Medical Research, Montréal, QC, Canada.
Senior author [email protected]
1
INTRODUCTION
Metal-on-metal (MM) total hip arthroplasty (THA) represents an
excellent alternative to metal-polyethylene bearings, in which
polyethylene particles have been designed as the main culprit in the
osteolysis. However, several studies have shown the presence of cobalt
(Co) and chromium (Cr) ions in blood, urine, and organs of patients after
THA using Co-Cr alloy-based implants (1). These ions are potentially
toxic for organism by leading to cellular toxicity, metal hypersensitivity
and chromosomal changes. Metal ions also have the potential to induce
oxidative stress in circulating cells. In the present study, we measured
the levels of different antioxidant enzymes protecting the organism by
scavenging reactive oxygen species (ROS) in blood of patients with MM
THA., glutathione peroxidase (GPx), and catalase (CAT) are considered
as classical antioxidant enzymes (2). On the other hand, heme
oxygenase-1 (HO-1) is a “non-conventional” anti-oxidant enzyme also
protecting the organism against oxidative stress (3). Total antioxidant
(TAS) levels as well as damages to lipids (peroxides) and proteins
(nitrotyrosine) were also evaluated.
METHODS
Blood from patients having 28 mm-head MM THAs was collected
up to 10 years post-operatively into Sarstedt Li-Heparin tubes and
divided in 5 groups: preoperative (PreOp;patients 46 patients), < 1 year
(40 patients), 1-2 years (23 patients), 3-4 years (28 patients), > 4 years
(36 patients). Preop patients were used as controls. Plasma was prepared
by centrifugation at 500 x g for 10 min. Plasma was chosen as opposed
to whole blood because it is known that the assays for oxidative stress
are not recommended for blood and can lead to artifacts. The activity of
GPx, and CAT was measured by enzymatic assays. The HO-1
concentration was assessed by a Stressgen ELISA test. Total antioxidant
levels were measured by the Oxford Biomedical total antioxidant power
assay to obtain an overview of the defense capacity of patients against
oxidative stress. Peroxide concentrations were measured by the
Biomedica OxyStat assay to quantify damage to lipids in the systemic
circulation. Nitrototyrosine levels were quantified using the
BIOXYTECH® Nitrotyrosine-EIA assay to measure damage to proteins.
Levels in patients without prostheses were used as control. ANOVA
followed by Fisher’s PLSD comparison test was used to compare the
different study groups.
radical produces depends on its origin and type, the most accurate and
clinically relevant measurement of oxidative damage is to measure
multiple products of this damage (5). In the present study, we measured
the concentrations of four antioxidant enzymes and three oxidative stress
markers in patients with MM bearings. The markers were chosen
because of their simplicity of measurement and because they are
sensitive enough to detect changes in several physio-pathological
conditions. Our results show that there were no changes in the levels of
these markers in patients with MM bearings compared to the control
group, suggesting that metal ions do not induce oxidative stress in blood
of patients with MM THA. Given the possible latency periods related to
metal ion exposure, longer follow-ups are however required to
conclusively determine the effects of elevated circulating ions on
oxidative stress in blood of patients with MM bearings.
A
B
C
RESULTS
Figure 1 shows the level of the different antioxidant enzymes in
patients with 28 mm-head MM THA at different time post-operatively.
Results showed that there was no difference in the level of GPx (Fig.
1A), CAT (Fig. 1B), and HO-1 (Fig. 1C) between the different groups.
Results also showed that there was no difference in the level of the
different oxidative stress markers (TAS, peroxides, and nitrotyrosines)
between the different groups (results not shown).
Finally, results showed that there was no relationship between the
concentrations of Co and Cr and the levels of antioxidant enzymes and
oxidative stress markers (results not shown).
DISCUSSION AND CONCLUSION
The single most significant obstacle preventing a broader
application of MM THA continues to be the concern regarding elevated
metal ion levels in the blood and urine of patients with this bearing
surface (4). Despite the concerns regarding chromosome aberrations and
translocations, changes in the proportions of peripheral blood
lymphocytes, and the risk of cancer which are continuously raised in the
literature, there is no conclusive evidence that elevated levels of Co and
Cr have any detrimental effects in patients (4). Metal ions have the
potential to induce the production of reactive oxygen species (ROS),
making them prime suspects for disturbing the balance of
oxidants/antioxidants in circulating cells. Since the damage that a free
Figure 1: Level of antioxidant enzymes in blood of patients with 28
mm-head MM THA: GPx (A), CAT (B), and HO-1 (C).
REFERENCES
1. Cobb AG et al. Proc Inst Mech Eng [H] 2006; 220:385-98.
2. Maritim AC et al. J Biochem Mol Toxicol 2003;17:24-38.
3. Ferrándiz ML et al. Curr Pharm Des 2008; 14:473-86.
4. MacDonald SJ. J Arthroplasty. 2004; 19(Suppl 3):71-7.
5. Argüelles S et al. Biochim Biophys Acta. 2004; 674:251-9.
This work was supported by the Natural Sciences and Engineering
Research Council of Canada and Fonds de Recherche sur la Nature et les
Technologies (Quebec).
Poster No. 2267 • 55th Annual Meeting of the Orthopaedic Research Society