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|Year : 2016 | Volume
| Issue : 2 | Page : 233-236
Elevated interictal serum galectin-3 levels in intractable epilepsy
Pei-Chao Tian1, Huai-Li Wang1, Guo-Hong Chen2, Jian-Hua Li1, Chen Zheng1, Yue Wang1
1 Department of Pediatrics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
2 Department of Neurology, Zhengzhou Children's Hospital, Zhengzhou, China
|Date of Web Publication||3-Mar-2016|
Department of Pediatrics, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou - 450053
Source of Support: None, Conflict of Interest: None
Background: Intractable epilepsy is defined as the occurrence of seizures that cannot be controlled with medical treatment. The discovery of epilepsy biomarkers is increasingly attracting more attention from both clinical physicians as well as neuroscientists. Increased levels of soluble and/or cellular galectin-3 (Gal-3) have been associated with various diseases. However, the effects of Gal-3 in epilepsy are still unknown. In this study, we evaluated the association of higher interictal serum Gal-3 protein levels in patients diagnosed with intractable epilepsy.
Patients and Methods: A group of 38 patients with intractable epilepsy and 26 healthy age-matched control subjects were included in this study. A commercially available electrochemiluminescence immunoassay (ECLIA) kit was used to determine serum Gal-3 protein levels.
Results: Our results indicated that serum Gal-3 protein level in the patient group was 6.67 ± 0.34 ng/ml, and in the age-matched control group was 5.40 ± 0.34 ng/ml. The difference between the two groups was found to be statistically significant (P = 0.003).
Conclusion: This study found a detectable elevation in serum Gal-3 concentration in patients with focal epilepsy. Given its secretory nature and detectable levels in the serum, Gal-3 could be a potential biomarker for intractable epilepsy.
Keywords: Biomarker; childhood; focal intractable epilepsy; galectin-3 (Gal-3)
|How to cite this article:|
Tian PC, Wang HL, Chen GH, Li JH, Zheng C, Wang Y. Elevated interictal serum galectin-3 levels in intractable epilepsy. Neurol India 2016;64:233-6
| » Introduction|| |
Epilepsy is a chronic brain disorder that is responsible for the patients experiencing recurrent unprovoked seizures over an extended period of time. This serious neurological condition is the most common neurological disorder found in children and is an important cause of mortality and disability in developing countries. In the immature brain of children, who do not have intracranial infections, metabolic disturbances, or a history of afebrile seizures, seizures are considered to be an age-dependent response to fever. Seizure control frequently requires administration of antiepileptic drugs. However, in patients with refractory or intractable epilepsy, it is difficult to achieve complete seizure control with increasing doses of anti-epieptic agents. Intractable epilepsy is a seizure disorder in which a patient's seizures cannot be controlled with treatment. Neuronal death is a significant feature of temporal epilepsy in humans. It has been found that prolonged and frequent occurrence of seizures increases the likelihood of neuronal damage in these patients.
The discovery of epilepsy biomarkers is increasingly attracting more attention from both clinical physicians and neuroscientists. Neurobiochemical and immunologic biomarkers correlating with brain damage are defined as biological indicators of the disease presence, activity, and/or progression. Among these, some proteins are believed to be peripheral biomarkers for neuronal damage. The galectin (Gal) family is characterized by a conserved sequence within the carbohydrate recognition domain (CRD) that has an affinity for β-galactoside residues, and galectin-3 (Gal-3) is an important member of the Gal family. Studies have shown that Gal-3 is expressed in the nucleus, cytoplasm, mitochondria, extracellular space, and on the cell surface. Multiple lines of evidence have shown the broad biological functionality of Gal-3, as it plays a pivotal role in the biological processes of cell adhesion, cell activation and chemo-attraction, cell growth and differentiation, the cell cycle, and apoptosis. Notably, increased levels of soluble and/or cellular Gal-3 have been associated with various diseases, including autoimmune diseases, cancers, and neurodegenerative diseases. However, the effects of Gal-3 in epilepsy remain unknown. In this study, we aimed to investigate the changes in serum Gal-3 protein levels in patients with intractable epilepsy.
| » Patients and Methods|| |
Patients and samples
This study was conducted from March 2012 to December 2013. Patients and healthy control subjects were recruited from the First Affiliated Hospital of Zhengzhou University Department of Pediatrics and the Zhengzhou Children's Hospital Department of Neurology. The study was conducted in accordance with the ethical principles approved by the First Affiliated Hospital of Zhengzhou University and the Zhengzhou Children's Hospital. Written informed consent was obtained from the parents or guardians of each participant. The control group consisted of 26 healthy subjects and the patient group consisted of 38 patients. Members of the patient group were admitted to the hospital after being diagnosed with intractable epilepsy. Patients with epileptic seizures and their families received a diagnosis based on the clinical semiology of epileptic seizures, electroencephalogram recordings, and findings from high-resolution brain magnetic resonance imaging (MRI). Patients who experienced persistent seizures despite the use of two or more antiepileptic drugs were diagnosed as having intractable epilepsy. Cases with symptomatic epilepsy resulting from post-traumatic reactions, metabolic or neurodegenerative diseases, cortical dysplasia, or nonepileptic paroxysmal events were excluded from the study.
The demographic data of the patients is shown in [Table 1]. Blood samples from the patients and healthy control subjects were centrifuged at 3500 rpm for 10 minutes. The supernatant serum samples were placed in Eppendorf tubes and frozen at −80°C until processing.
Determination of serum Gal-3 level
Serum Gal-3 protein concentration was measured using a commercially available electrochemiluminescence immunoassay (ECLIA) kit (R and D Systems, USA) according to the manufacturer's instructions. Briefly, 100 µl of serum was added to appropriate wells of ELISA plates coated with anti-Gal-3 antibodies. The plates were covered with an adhesive plastic and incubated at 37°C for 2 hours. Then, the plate was washed three times with 200 µl of washing buffer, followed by incubation at room temperature (RT) for 2 hours with horseradish peroxidase-conjugated secondary antibody. Next, 100 µl of tetramethylbenzidine (TMB) reagent was added to each well using a multichannel pipette. After sufficient color development, 100 µl of stop buffer was added to the wells. The absorbance of each well was read at 450 nm.
All statistical analyses were performed using the SPSS 19 statistical analysis software package (SPSS, Munich, Germany). Conformity to normal distribution of quantitative data was analyzed using the Kolmogorov–Smirnov test. The data were presented as means ± standard deviations. The Chi-square test was used to compare categorical variables between the two groups. An independent-sample t-test was used for the comparison of continuous variables between the patient and the control groups. One-way analysis of variance with a post hoc Bonferroni test was used for the normally distributed continuous data. P < 0.05 was considered to be statistically significant.
| » Results|| |
Serum Gal-3 protein levels were determined by enzyme-linked immunosorbent assay (ELISA) in both the patient and the control groups. The results are presented in [Table 2] and [Figure 1]. ELISA results indicated that the mean serum Gal-3 protein level in the patient group was 6.67 ± 0.34 ng/ml, and in the control group was 5.40 ± 0.34 ng/ml. A statistically significant difference in serum Gal-3 protein levels was determined between the patient and the control groups (P = 0.04).
|Table 2: Mean serum Gal-3 protein levels in the patient and the control groups|
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|Figure 1: Serum galectin-3 (Gal-3) protein levels in the patient and the control groups|
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The patient group included 21 cases of generalized epilepsy and 17 cases of partial epilepsy. The clinical generalized epilepsy cases comprised idiopathic generalized tonic–clonic epilepsy, juvenile absence epilepsy, and juvenile myoclonic epilepsy. The partial epilepsy cases comprised extratemporal lobe epilepsy and temporal lobe epilepsy [Table 2].
We then compared the mean serum Gal-3 levels between the generalized epilepsy patient group and the partial epilepsy patient group. The results indicated that the mean Gal-3 concentration in the generalized epilepsy patient group was 5.23 ± 0.45 ng/ml, and in the partial epilepsy patient group was 7.83 ± 0.68 ng/ml. Importantly, a statistically significant difference was seen in serum Gal-3 protein levels between the generalized epilepsy group and the partial epilepsy group (P = 0.003) [Table 3]. However, there was no statistically significant difference in serum Gal-3 levels between patients using various combinations of antiepileptic medications or between male and female patients (P > 0.05).
|Table 3: Comparison of serum Gal-3 protein levels between the generalized and the partial epilepsy groups and the control group|
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| » Discussion|| |
Epilepsy is a neurological disorder in which nerve cell activity in the brain is disturbed, causing a seizure. In most cases, seizures can be controlled using medications. However, 20%–30% of these patients are diagnosed as having treatment-resistant epilepsy. Multiple lines of evidence have shown that the frequent recurrence of epileptic seizures increases the likelihood of neuronal damage. Therefore, treatment must be directed towards the support of vital functions and in controlling seizures in the shortest possible time for these patients.
Gal-3 is a multifunctional lectin involved in a number of critical biological processes including apoptosis, immune activation, and cell cycle, all of which are implicated in the development of epilepsy. The major finding of this study is that the presence of Gal-3 is significantly increased in the serum of patients with epilepsy. Previous studies have reported the potential roles of Gal-3 in neurodegenerative diseases. Jin et al., revealed that Gal-3 expression was upregulated at both the protein and the mRNA levels in scrapie-affected brains during the process of neurodegeneration in prion diseases. In addition, a recent study demonstrated that an increased Gal-3 level is a potential biomarker for amyotrophic lateral sclerosis (ALS). Interestingly, patients with Alzheimer's disease (AD) were found to have an increased serum Gal-3 level as compared with control participants. The degree of cognitive impairment, as measured by the Mini–Mental Status Examination, was found to have a significant correlation with serum Gal-3 levels in both patients and healthy control subjects. Based on these findings, it was suggested that serum Gal-3 could be a potential biomarker for the diagnosis of AD. Gal-3 induction has also been seen in ischemic brain lesions. With regard to epilepsy, a recent study reported that Gal-1 plays an essential role in the neurodegeneration process triggered in the forebrain of rodent epilepsy models assayed using systemic pilocarpine administration. Notably, it was also found that Gal-3 is strongly upregulated as early as 24 hours after the occurrence of pilocarpine-induced seizures and has an expression pattern closely matching that of neuronal degeneration revealed by Fluoro-Jade B (FJB) staining in the hippocampus and cortex.
| » Conclusion|| |
In conclusion, this study found a detectable elevation in serum Gal-3 concentrations in patients with epilepsy. Given its secretory nature and detectable levels in the serum, Gal-3 could be a potential biomarker for the diagnosis of intractable epilepsy. However, this study also presents several drawbacks. Increased levels of Gal-3 may either suggest that Gal-3 plays a potential role in the pathological process of seizure or that it is a compensatory survival response. Therefore, it is still unknown whether interfering with the activity of Gal-3 in epilepsy could represent a new possibility for reducing neuron loss in humans. In addition, it is also unknown if an increase in Gal-3 levels would be detectable early in patients who will later develop drug-resistant epilepsy; or, if this increase is somehow a byproduct of the disease after it has already been established. Further research is needed to provide a more complete picture of the underlying mechanisms behind this finding.
Financial support and sponsorship
Conflicts of interest
The authors declare that they have no conflicts of interest.
| » References|| |
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[Table 1], [Table 2], [Table 3]