НЕЙРОХИМИЯ, 2011, том 28, № 2, с. 158-163
КЛИНИЧЕСКАЯ НЕЙРОХИМИЯ
YM 577
EXPRESSION OF GLOBAL OXIDATIVE STRESS AND MATRIX METALLOPROTEINASES IS ASSOCIATED WITH RETT SYNDROME
© 2011 E. Carmeli", *, A. Bachar*, R. Beiker"
aSackler Faculty of Medicine, Stanley Steyer School of Health Professions, Tel Aviv University, Israel bNeve Ram, Residential Care Center, Rechasim, Israel
Abstract—Rett syndrome (RTT) is characterized by microcephaly, cognitive impairment, abnormal muscle tone, epilepsy, and ataxia, yet misdiagnoses are not uncommon. Oxidative stress (OS) and matrix metallopro-teinases (MMPs) has been implicated in a variety of neurological diseases and inflammatory conditions. The aims of the study were to investigate the serum values of global oxidative stress (OS) and levels of MMP-2 (gelatinase), MMP-9 and 13 (collagenase) in RTT girls, since we hypothesized that OS and MMPs play a role in the on-going pathological processes of RS leading to the progression and deterioration of their neurological functions. Total level of MMP-2, 9 and 13 were measured in serum of six RTT girls (average age of 14.2 ± 1.6) by ELISA, and global OS was measured by CR 3000 instrument, FORM system. The RTT girls had significant (p = 0.001) increased serum levels of MMP-2 (mean values) and MMP-9 (mean values), yet MMP-13 mean values were comparable to age-and-gender matched non RTT girls. OS values were significantly higher in RTT girls comparing control groups. The increased OS values and MMP-2 and 9 levels in RTT girls suggest their involvement in the chronic pathogenesis resulting in continuing neurological damage. Our findings can provide another aspect indicating certain MMPs and OS as possible biochemical markers and their potential application in future therapeutic strategies.
Keywords: Rett syndrome, matrix metalloproteinase, oxidative stress.
INTRODUCTION
Rett syndrome (RTT) is a progressive neuro-devel-opmental disorder that predominantly affects girls and is the most common genetic cause of intellectual disability in females. Most cases are due to sporadic mutations of methyl-CpG-bindingprotein-2 (MeCP2) locating near the end of the long arm of the X chromosome. MeCP2 binds methylated DNA and acts as a transcriptional repressor and its mutation can lead to disruption of methylation imprinting of the UBE3A gene [1]. MeCP2 regulates over one thousand genes, both as a repressor and activator [2, 3]. The transcriptional changes suggest that the duplication phenotype is due to MeCP2 gain of function (hypermorph), rather than loss of function, and that at the molecular level, RTT is due mostly to loss of transcriptional activation, rather than derepression. In terms of clinical relevance, results suggest that patients with RTT will have to be treated differently than patients with MeCP2 duplications. The finding that MeCP2 regulates a large number of genes, at least in the hypothalamus, suggests a need for therapeutic strategies that focus on restoring neuronal function rather than restoring the activity of individual gene products affected by MeCP2 dysfunction.
* Corresponding author; address: Department of Physical Therapy, Sackler Faculty of Medicine, Stanley Steyer School of Health Professions, Tel Aviv University, Ramat Aviv 69978, Israel; e-mail: elie@post.tau.ac.il.
Typically, RTT is characterized by a period of 1— 2 years of nearly normal development followed by regression of psychomotor function, cognitive abilities and communication skills, combined with the occurrence of specific features, including hand stereotype movements, epilepsy, and abnormal muscle tone, with increased deep tendon reflex, pes equinovarus or pes valgus, and scoliosis. As the syndrome is progressing more orthopedic deformities and neurologic deficits might be presented.
Matrix metalloproteinases (MMPs) belong to a family of zinc-binding proteolytic enzymes and are among others responsible for the digestion of almost all components of the extracellular matrix [4]. MMPs are tightly regulated endopeptidases that degrade extracellular matrix components.
MMP-2 (gelatinase-A, 72 kDa) is mainly digests collagen types 1, 2, 3, fibrillin, fibronectin, tenascin, osteonectin, and elastin. Both MMP-2 and MMP-9 show structural similarity with fibronectin. MMP-2 is commonly found and synthesized by many cells, especially by fibroblasts, keratinocytes, chondrocytes, endothelial cells, monocytes, and osteoblasts. Unlike MMP-2, which is constitutively active, MMP-9 (gelatinase-B, 92 kDa) is inducible and normally present at low levels and is markedly upregulated in inflammation. MMP-9 plays a critical role in the degradation and remodeling of
Table 1. Clinical characteristic of Rett syndrome individuals
Individuals 1 2 3 4 5 6 7 8
Intellectual disability V V V V V V V V
Orthopedic deformity (i.e., scoliosis, foot deformity) V V V - V V V -
Stereotype movements V V - V V V - V
Speech disorders V V V - V V V V
walking disability - V V - - V - -
abnormal muscle tone V V V V V V V V
epilepsy - V - V - - V -
bruxism - V V V - V - V
the extracellular matrix components that form a scaffold of the blood-brain barrier. MMP-13 (collagenase-3, 60 kDa) is mainly produced during malignancy processes by influencing tumor growth via release of matrix-bound growth factors. MMP-13 cleaves collagens type 1, 2, and 3, and can also digest other ECM molecules and soluble proteins [5]. MMP-13 is mainly produced during tumorogenesis and in some physiologic processes associated with an accelerated change of the ECM [6]. Consequently, these three MMPs play an important role not only in physiological conditions according to tissue remodeling during development and homeostasis, but also in neuro-pathological processes like cerebrovascular ischemia [7], breakdown of the blood-brain barrier (BBB), vascular edema, hemorrhage [8], vascular dementia [9], focal ischemia [10], CNS and PNS trauma [11—12], and other neurodegenerative disorders such as multiple sclerosis, Alzheimer disease, Parkinson, in motor neuron disease such as Amyotrophic lateral sclerosis (ALS), and in neuro-pathological disease such as prion disease [13].
Oxidative stress (OS) is thought to play a central role in neuropathological diseases, and can be the result of exposure to toxins (e.g., drugs) or pathogens; a low antioxidant defense system; inappropriate life style (lack of physical activity, poor diet) and by-products of normal metabolism [14]. Previous studies demonstrated
that OS levels were higher in the Down syndrome group compared with the control group [15].
Therefore, the major aim of this study was to investigate the global OS values as well as the systemic level of MMPs in RTT girls, since we hypothesized that OS and MMPs play a role in the on-going pathological processes of RTT leading to the progression and deterioration of their neurological functions.
METHODS
Sera from 6 out of 8 girls (average age of 14.2 ± 1.6) with RTT were provided by a nurse practitioner. RTT was clinically diagnosed by two neuro-pediatric physicians. All RTT girls had lived at least five years in the residential care center, and required moderate assistance for most of the daily activities. Their clinical characteristics of the RTT participants are demonstrated in Table 1. RTT girls who met at least 5 out of 8 criteria of the clinical characteristics participated in the study. After being referred to the study by the institutional physician, the study was approved by the Institutional Ethic Committee of Residential Care Center under the administrative control of the Israeli Ministry of Welfare, and written consent was obtained from their guardians. Unspecified mentally retarded (MR) girls (n = 7) [average age of 15.3 ± 1.8] and healthy girls (n = 8) [average age of15.1 ± 2.3] with age- matched served as two con-
160
CARMELI et al.
trol groups. To eliminate the factors which might trigger any inflammatory process in the blood we excluded from the study all individuals with one of the following conditions: diabetes mellitus, obesity, taking dopamine, lithium or glucocorticoids, chronic or acute heart failure, hyperlipidaemia and liver, adrenal or kidney diseases.
A total of seven ml of venous blood samples were collected into anti-coagulant tube after overnight fasting and the sera were obtained by centrifugation within 24 hours after blood removal (15 min at 1215 g), and were kept frozen at —20°C until analysis. Serum MMP total levels were measured by using a quantitative sandwich enzyme-linked immunosorbent assay (ELISA) test (i.e., the sample with an unknown amount of antigen was immobilized on a solid support (a polystyrene microtiter plate) specifically (via capture by another antibody specific to the same antigen) (R&D Systems Europe, Abingdon, UK) according to the manufacturer's guidelines [16]. All samples were measured as duplicates. The mean was calculated for data analysis. The optical density was measured at 450 nm.
Global Oxidative Stress Analysis
The analyses were carried out using CR 3000 instrument (FORM system, Catellani Group, Callegari S.p.A, Parma, Italy). All measurements were performed within 0.30—1.00 hour post blood taking.
The CR 3000 instrument includes software and photometers (505 nm) with one or three reading cells for the determination of primary tests on whole capillary blood. The CR 3000 kits include ready filled cuvettes (4.8 pH buffered chromogen) that are bar coded (so that the reader automatically recognizes the test about to be performed and the ^-factor), and capillaries for blood collection. The prepared reagents are able to promote the iron-catalyzed Haber-Weiss reaction. After an overnight fast (8-10-h), and between 08:00-09:00 a.m., a total of one drop of capillary blood samples, approximately 10 pi, were drawn from the subject's finger, and inserted into the prepared cuvette. The cuvette was then gently rocked several times until the sample was completel
Для дальнейшего прочтения статьи необходимо приобрести полный текст. Статьи высылаются в формате PDF на указанную при оплате почту. Время доставки составляет менее 10 минут. Стоимость одной статьи — 150 рублей.