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Table of Contents
ORIGINAL ARTICLES
Year : 2019  |  Volume : 2  |  Issue : 3  |  Page : 109-114

Role of DJ-1 and Apo A1 as biomarkers in Parkinson’s disease: an observational case-control study


1 Department of Neurology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
2 Department of Pharmacology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
3 Department of Nuclear Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
4 Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India

Date of Submission12-Sep-2019
Date of Decision05-Nov-2019
Date of Acceptance14-Nov-2019
Date of Web Publication04-Dec-2019

Correspondence Address:
Dr. Sahil Mehta
Level 1, Room Number: 13, Department of Neurology, Nehru Hospital, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/AOMD.AOMD_23_19

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  Abstract 

AIM: Premotor phase in Parkinson’s disease (PD) begins many years before the onset of motor symptoms. Despite advancement in the understanding of this common neurodegenerative disease, clinical diagnosis is still the gold standard. Various fluid- and tissue-based biomarkers have been postulated to play a role in the pathogenesis of PD. We aimed to study the role of serum DJ-1 and apolipoprotein A1 (Apo A1) in PD. SETTINGS AND DESIGN: A cross-sectional observational study was conducted in the Department of Neurology, in collaboration with the Department of Pharmacology. Cases of PD and healthy controls were recruited over 1 year with written informed consent from all the participants. The study was approved by the institutional ethics committee. SUBJECTS AND METHODS: All cases underwent detailed neurological examination, Hoehn and Yahr staging, and MDS-UPDRS (MDS-UPDRS (Movement Disorders Society–Unified Parkinson Disease Rating Scale) scoring. Serum of all the cases and controls were collected for the estimation of DJ-1 and Apo A1 by enzyme-linked immunosorbent assay. STATISTICAL ANALYSIS: Serum DJ-1 and Apo A1 levels were compared between cases and controls using Mann–Whitney test. Correlation of characteristics was carried out using Spearman correlation coefficient. RESULTS: The study cohort included 77 cases of PD and 69 healthy controls. Serum DJ-1 and Apo A1 levels were found to be significantly lower in cases compared to controls (P < 0.001). However, no correlation was found with age of onset, duration of disease, and severity of illness. A negative correlation was observed between DJ-1 levels and cognitive impairment and bladder dysfunction. CONCLUSION: Low levels of DJ-1 and Apo A1 are found in patients with PD of Indian origin. However, correlation of these biomarkers with progression and severity is needed to be explored in future randomized controlled trials with a large sample size.

Keywords: Apolipoprotein A1, biomarkers, DJ-1, idiopathic Parkinson’s disease


How to cite this article:
Shree R, Mulagala M, Mehta S, Sood A, Modi M, Goyal MK, Goyal G, Medhi B, Mittal BR, Lal V. Role of DJ-1 and Apo A1 as biomarkers in Parkinson’s disease: an observational case-control study. Ann Mov Disord 2019;2:109-14

How to cite this URL:
Shree R, Mulagala M, Mehta S, Sood A, Modi M, Goyal MK, Goyal G, Medhi B, Mittal BR, Lal V. Role of DJ-1 and Apo A1 as biomarkers in Parkinson’s disease: an observational case-control study. Ann Mov Disord [serial online] 2019 [cited 2020 Jan 18];2:109-14. Available from: http://www.aomd.in/text.asp?2019/2/3/109/272286




  Key messages: Top


  • Low DJ-1 and Apo A1 levels were found to be associated with Parkinson’s disease in Indian population.


  • In contrast with the previous literature, their role with the onset, severity, and progression of symptoms cannot be determined clearly in this study.



  •   Introduction Top


    Parkinson’s disease (PD) is a neurodegenerative disorder, and its pathogenesis involves oxidative damage and neuroinflammation.[1] Comprehensive clinical, imaging, and body fluid biomarkers are being explored to find out a set of specific biomarkers, which can diagnose preclinical and prodromal PD accurately and predict the progression of the disease over time.[2] Various blood-based and cerebrospinal fluid (CSF) biomarkers have been studied but their role in the pathogenesis of PD require more clarification.

    DJ-1 is an antioxidant protein normally expressed in both cerebral and extra-cerebral tissues. Nagakubo et al.[3] first isolated and characterized deoxyribonucleic acid (DNA)-encoding DJ-1 protein in 1997 and showed its role in Ras-related signal transduction pathway. It acts as a cellular sensor of oxidative stress and protects them from free radical damage. Mutations in DJ-1 are associated with early-onset autosomal-recessive PD.[4] Previous studies, which have assessed the role of DJ-1 in either serum or CSF, have generated conflicting results. Waragai et al.[5] in their preliminary work of 40 patients with PD proposed it as a biomarker in CSF on the basis of higher levels in comparison to non-PD controls. They suggested that there is upregulation of DJ-1 in PD as a compensatory protective mechanism, especially in the early stages of PD. Waragai et al.[6] further evaluated DJ-1 levels in the plasma of 104 patients with PD, 30 with dementia with Lewy bodies (DLB), and 80 controls. The authors found that plasma DJ-1 levels were significantly higher in both PD and DLB as compared to controls and also correlated with the severity of the disease. Their work primarily involved participants from Japan. On the contrary, Maita et al.[7] neither found any significant difference of serum DJ-1 levels between patients with PD and controls nor their correlation with the severity of disease. Similarly, An et al.[8] also did not find any difference of DJ-1 levels between patients and controls in their study from China. All these studies suggest that the role of DJ-1 in PD has to be evaluated further before it can be considered as a potential biomarker in the diagnosis and pathogenesis of PD.

    Apolipoprotein A1 (Apo A1) is a major component of high-density lipoprotein; its protective role in cardiovascular diseases is known since decades.[9] Recently, studies in the literature have reported that lower levels of Apo A1 are associated with not only higher risk of developing PD but also with the development of more severe disease and early age of onset of PD.[10],[11],[12] Qiang et al.[10] in their study found a significant correlation between low Apo A1 levels and earlier age of onset and clinically more severe PD. Moreover, they also studied asymptomatic patients with PD from Parkinson Associated Risk Syndrome (PARS) cohort and found lower levels in the patients with <80% DAT (dopamine transporter) uptake compared with normal DAT uptake.[10] Epidemiological studies have shown lower risk of PD among statin users, which indirectly suggests association between Apo A1 and PD.[13],[14]

    To the best of our knowledge, these biomarkers have not been studied in Indian population. With this background in mind, we investigated the role of DJ-1 and Apo A1 as blood-based biomarkers in Indian patients with PD.


      Subjects and Methods Top


    Study characteristics: A cross-sectional observational study was conducted at Postgraduate Institute of Medical Education and Research, Chandigarh, a tertiary care center in North India in the Department of Neurology, in collaboration with the Department of Pharmacology. Cases and healthy controls were recruited from December 2015 to December 2016 over a period of 1 year. Written informed consent was obtained from all the participants included in the study. The study was approved by the institutional ethics committee (INT/IEC/2015/821).

    Inclusion criteria: Cases fulfilling UK Parkinson’s Disease Society Brain Bank clinical diagnostic criteria for clinical diagnosis of idiopathic PD comprised the inclusion criteria.[13]

    Exclusion criteria: Secondary  Parkinsonism More Details including vascular parkinsonism, atypical parkinsonian syndromes (progressive supranuclear palsy, multiple system atrophy, corticobasal ganglionic degeneration, and DLB), past history of major head injury, past history of encephalitis, neuroleptic treatment at the onset of symptoms, history of psychiatric disease, presence of structural lesion or hydrocephalus on brain imaging, and other reversible causes of parkinsonism were included in exclusion criteria.

    All patients underwent detailed clinical and neurological examination. Hoehn and Yahr (H and Y) staging and MDS–UPDRS (Movement Disorders Society–Unified Parkinson Disease Rating Scale) scoring were carried out for all the cases. Three authors (RS, MM, and SM) performed the detailed clinical evaluation and UPDRS scoring, and all three of them were certified by the International Parkinson and Movement Disorders Society. The blood samples were collected from patients and controls in clot-activated vacutainers and then immediately centrifuged to obtain serum. Serum was stored at -20°C until the measurement of serum DJ-1 and Apo A1 levels.

    Estimation of DJ-1 by enzyme-linked immunosorbent assay (ELISA): Serum DJ-1 was measured by Human DJ-1/ PARK7 ELISA kit (Catalog No. QY-E05415, Qayee-Bio, Shanghai, China). It is an in vitro ELISA for the quantitative measurement of Human DJ-1 in serum, plasma, and cell culture supernatants. The sensitivity of the assay was 1.85ng/mL with the coefficient of variation of less than 15%.

    Estimation of Apo A1 by ELISA: Serum Apo A1 was measured in a similar way by Human Apo A1 ELISA kit (Catalog No. EA5201-1, ASSAYPRO, St. Charles, Missouri). It is an in vitro ELISA for the quantitative measurement of human Apo A1 in serum, plasma, and cell culture supernatants. The intra-assay precision of the kit was 4.4%.

    Statistical analysis: The data were statistically analyzed using commercially available software package the Statistical Package for the Social Sciences (version 22.0, IBM, Armonk, New York). To find the pattern of distribution of data, Shapiro–Wilk test was conducted. Comparisons of biomarkers (ApoA1 and DJ-1) between two groups were carried out by Mann–Whitney test. The values were expressed as median and interquartile range (IQR) as well as mean ± standard deviation (SD). Spearman correlation coefficient was used to compare the correlation of characteristics such as duration of illness, UPDRS motor score, levodopa equivalent dose (LED), rapid eye movement sleep behavior disorder (RBD), H and Y stage, age at presentation, age at onset, Mini Mental Status Examination (MMSE), and non-motor symptoms with serum Apo A1 and DJ-1 levels. The significance of the difference was defined as P < 0.05.


      Results Top


    Demographic and clinical characteristics: Among 100 subjects who were screened for the study, 23 were excluded as they were diagnosed with one of the atypical parkinsonian disorders. Finally, 77 patients with IPD and 69 healthy controls were studied. Baseline characteristics of the participants are summarized in [Table 1]. The mean age of the patients at the onset of IPD was 53.21 years, 23.4% had onset before the age of 50 years (young-onset Parkinson’s disease, YOPD). The mean duration of illness was 4.3 years. A total of 24.7% patients were drug naïve and 26% had a history of RBD.
    Table 1: Demographic and clinical characteristics of idiopathic Parkinson disease and controls

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    Comparison between cases and controls: Statistical analysis using Mann–Whitney test revealed significant difference between the values of both biomarkers [Table 2]. Serum Apo A1 levels were significantly reduced in patients with IPD compared to controls, 112.93mg/dL (IQR: 111.22–119.24mg/dL) and 119.49mg/dL (IQR: 113.98–120.44mg/dL), respectively, with P < 0.001. Similarly, serum DJ-1 levels were also significantly reduced in IPD cases, 85.9ng/mL (IQR: 58.58–107.96ng/dL) and 106.43ng/mL (IQR: 87.16–137.68ng/mL) in cases and controls, respectively, with P < 0.001.
    Table 2: Comparison of serum DJ-1 and serum Apo A1 values between total cases and controls

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    Comparison of biomarkers with patient characteristics: When serum Apo A1 levels were correlated with various characteristics [Table 3], significant correlation was found with RBD (P = 0.002, correlation coefficient = 0.35). Patients of IPD with a history of RBD had higher Apo A1 levels compared to those without a history of RBD. However, no correlation was observed between serum Apo A1 levels and duration of illness, UPDRS motor score, LED, H and Y stage, age at onset, and MMSE. No correlation was found between serum DJ-1 and RBD, duration of illness, UPDRS motor score, LED, H and Y stage, age at onset, and MMSE [Table 4].
    Table 3: Correlation between serum Apo A1 levels and patient characteristics

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    ,
    Table 4: Correlation between serum DJ-1 levels and patient characteristics

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    Comparison of biomarkers with non-motor symptoms: Serum DJ-1 levels were found to be negatively correlated with cognition (P = 0.004, R = -0.23), and a trend toward significance was found when correlated with anxiety (P = 0.054, R = 0.22) and bladder symptoms (P = 0.07, R = -0.20) [Table 5]. No correlation was observed between serum Apo A1 levels and any of the non-motor symptoms [Table 6].
    Table 5: Correlation between serum DJ-1 levels and non-motor symptoms

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    ,
    Table 6: Correlation between serum Apo A1 levels and non-motor symptoms

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      Discussion Top


    In our study, we found that serum DJ-1 levels were significantly decreased in patients with PD as compared to normal healthy controls. There are variable and even contradictory reports on this subject in the existing literature. Waragai et al.[6] found that plasma DJ-1 levels were significantly increased in patients with PD as compared to controls and also correlated with the progression of the disease (significantly higher levels in advanced as compared to early PD). They hypothesized that DJ-1 levels are increased in response to oxidative stress in the body. On the contrary, Maita et al.[7] did not find any significant differences in DJ-1 levels between patients with PD and controls. Moreover, they did not find any correlation between DJ-1 levels and the stage of disease, which is also reflected in our study. Similarly, Shi et al.[15] could not find any significant correlation between CSF DJ-1 levels of patients with PD and controls. Lin et al.[16] measured DJ-1 levels in blood instead of serum; however in this study too, they could not find any significant increase in DJ-1 levels as compared to normal controls. It is well known that DJ-1 exerts its neuroprotective function by regulating mitochondrial dynamics. Loss of DJ-1 leads to altered mitochondrial homeostasis with increased oxidative stress–induced damage and increased free radical production.[17],[18],[19]

    We did not find any correlation between serum DJ-1 levels with disease severity as measured by H and Y staging (P = 0.08) [Table 4] as seen in the studies by Maita et al.[7] and An et al.[8] who also did not find any significant difference between the levels in early-stage and late-stage PD. On the contrary, Waragai et al.[6] showed a correlation of plasma DJ-1 levels with the disease severity; they found that plasma DJ-1 levels were significantly higher in advanced stages of IPD (Yahr III–V) than early stages of disease (Yahr I–II) (P = 0.028).

    A plausible reason for different results in different studies could lie in the methodological variability, technical differences, or some other confounding variables. There are various methods to assess the levels of these biomarkers namely Luminex assay, Western blot, high-performance liquid chromatography, and ELISA. Luminex assay is a quantitative bead-based flow cytometric assay with high sensitivity and efficiency.[20]

    Another reason for the lack of correlation between DJ-1 and motor severity and stage of the disease could lie in the reason that we have not performed longitudinal biochemical and clinical assessments on follow-up.

    A negative correlation was observed between DJ-1 levels and cognitive impairment [Table 5]. Patients of PD with a more severe cognitive impairment had a significantly lower levels compared to those with a less severe cognitive impairment. DJ-1 mutation–associated PD is characterized by early onset of disease with prominent focal dystonia and good response to levodopa.[21] However, there are pathologically proven cases of DJ-1 mutation–associated PD with prominent dementia in whom Lewy body pathology was found in locus coeruleus, nucleus basalis of Meynert, and neocortex.[22] Furthermore, it has been seen in animal models that DJ-1-deficient mice show less tyrosine hydroxylase–positive neurons in ventral tegmental area and show both motor dysfunction and non-motor cognitive and behavioral impairments.[23] DJ-1 is not only involved in dopaminergic neurotransmission but is also shown to be essential for long-term depression at CA1 synapse in hippocampal neurons involved in memory.[24] Similarly, a negative correlation was observed between bladder dysfunction and DJ-1 levels (trend toward significance) [Table 5]. These findings have to be replicated in studies with a large sample size to confirm their association.

    In agreement with previous studies, our study also showed that serum Apo A1 levels were lower in patients with PD when compared with normal healthy controls, and the results were statistically significant (P < 0.001) [Table 2]. There are only a few reported studies in literature comparing serum Apo A1 between PD and normal subjects. Wang et al.[12] focused on the role of Apo A1 as a biomarker in PD in their proteomic analysis and found that one isoform was increased in CSF, whereas another one was decreased in CSF. Our results are comparable with Qiang et al.[10] who also found lower Apo A1 levels in patients with PD and found lower Apo A1 levels to correlate with earlier age of onset. However, we did not find any correlation with the age of onset of PD. Further, we did not observe any significant correlation between levels of serum Apo A1 and disease severity as measured by UPDRS score [Table 3] similar to a study by Swanson et al.[11]

    A positive correlation was seen between the presence of RBD and Apo A1 levels. Patients of PD with a history of RBD had higher Apo A1 levels compared to those without a history of RBD. This finding is contrary to the fact that RBD is a prodromal marker for PD, hence the values of serum Apo A-1 should have been lower in patients with RBD in comparison to patients without a history of RBD. Treatment with levodopa might have confounded the results. Moreover, we have not carried out polysomnographic studies to confirm the RBD, and patients having other parasomnias may have been included.

    Limitations of our study were the nonrandomized design and the small sample size compared to the prevalence of PD. Second, we did not study these biomarkers in CSF because of ethical concerns. Third, ELISA technique was used to analyze the levels of the biomarkers, although the most sensitive technique was Luminex assay, which could have resulted in contradictory results in comparison to previous studies.

    On the basis of these findings, we conclude that plasma DJ-1 and Apo A1 levels are considered as potential biomarkers in PD. No correlation is observed between the level of these biomarkers and the age of onset and severity of the disease. The results in our population are different from studies from different parts of the world. Different genetic and environmental factors may have contributed to such findings. Further prospective randomized controlled trials with larger sample size and longitudinal follow-up are needed to confirm the findings of our study. More sensitive techniques such as quantitative Western blotting and Luminex assays can be used for the biochemical estimation of these biomarkers.

    Financial support and sponsorship

    Nil.

    Conflicts of interest

    There are no conflicts of interest.



     
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        Tables

      [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



     

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