AMYOTROPHIC LATERAL SCLEROSIS DIAGNOSTIC COMPOSITION USING ACID SPHINGOMYELINASE, AND METHOD FOR DETECTING DIAGNOSTIC MARKERS

Abstract

The present invention relates to a amyotrophic lateral sclerosis (ALS) diagnostic composition using acid sphingomyelinase (ASM), and a method for detecting diagnostic markers and, more specifically, to a method and a composition for detecting markers for ALS, the method comprising the steps of: (a) providing a sample of a subject; (b) measuring the ASM expression level or the enzyme activation level in the sample; (c) determining that a subject, of which the ASM expression level or the enzyme activation level is increased compared to that of a normal person, has ALS. According to the investigation of the present inventors, the activity of ASM, among lipids and enzymes related to the sphingolipid metabolism, is specifically increased in a sample of an ALS patient compared to that of a normal person. ASM can be used as a marker for diagnosing ALS, thereby enabling the development of a novel and effective diagnostic reagent.

Claims

1. A method for detecting a marker of amyotrophic lateral sclerosis (ALS) to provide information necessary for diagnosis of ALS, the method comprising the steps of: (a) providing a sample of a subject; (b) measuring the expression level or enzymatic activity level of acid sphingomyelinase (ASM) in the sample; and (c) determining the subject as having ALS if the expression level or enzymatic activity level of ASM in the subject is increased compared with that of a normal control.

2. The method of claim 1, wherein the subject is a patient having a mutation of at least one gene selected from the group consisting of FUS, SOD1, TBK1, C9orf72, TARDBP, OPTN, and NEK1, or a sporadic ALS patient.

3. The method of claim 1, wherein the subject is a Korean.

4. The method of claim 1, wherein the sample is selected from the group consisting of skin tissue, nerve tissue, whole blood, plasma, serum, cerebrospinal fluid, urine, saliva, nasal discharge, sputum, bone marrow, amniotic fluid, ascitic fluid, and cervical or vaginal discharge.

5. The method of claim 1, wherein the measuring of the expression level of ASM is performed by measuring the expression level of ASM protein or ASM mRNA.

6. A composition for diagnosis of amyotrophic lateral sclerosis, the composition comprising an agent for measuring the enzymatic activity of ASM.

7. A composition for diagnosis of amyotrophic lateral sclerosis, the composition comprising an agent for measuring the expression level of ASM protein or ASM mRNA.

8. Use of acid sphingomyelinase (ASM) for preparing an agent for diagnosis of amyotrophic lateral sclerosis (ALS).

9. The use of claim 8, wherein the agent for diagnosis of amyotrophic lateral sclerosis (ALS) measures the enzymatic activity of ASM.

10. The use of claim 8, wherein the agent for diagnosis of amyotrophic lateral sclerosis (ALS) measures the expression level of ASM protein or mRNA.

11. The use of claim 8, wherein a patient having a mutation of at least one gene selected from the group consisting of FUS, SOD1, TBK1, C9orf72, TARDBP, OPTN, and NEK1, or a sporadic ALS patient is used as a subject for diagnosis of amyotrophic lateral sclerosis (ALS).

12. The use of claim 10, wherein the subject is a Korean.

13. The use of claim 10, wherein any one selected from the group consisting of skin tissue, nerve tissue, whole blood, plasma, serum, cerebrospinal fluid, urine, saliva, nasal discharge, sputum, bone marrow, amniotic fluid, ascitic fluid, and cervical or vaginal discharge is used as a sample.

14. A method for diagnosis of amyotrophic lateral sclerosis (ALS), the method comprising the steps of: (a) providing a sample of a subject; (b) measuring the expression level or enzymatic activity level of acid sphingomyelinase (ASM) in the sample; and (c) determining the subject as having ALS if the expression level or enzymatic activity level of ASM in the subject is increased compared with that of a normal control.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0089] FIG. 1 is a schematic diagram showing enzymes involved in a sphingolipid metabolism.

[0090] FIG. 2 shows the levels of sphingomyelin, ceramide, and sphingosine, measured in the plasma of normal controls and ALS patients (FUS, SOD1, TBK1).

[0091] FIG. 3 shows the activity levels of acid sphingomyelinase and acid ceramidase measured in the plasma of normal controls and ALS patients (FUS, SOD1, TBK1). The marks * and ** indicate a statistically significant difference, respectively.

[0092] FIG. 4 shows the enzymatic activity level of acid sphingomyelinase measured in induced neurons from normal controls and ALS patients (FUS, SOD1, TBK1), respectively. The mark indicates a statistically significant difference.

MODE FOR CARRYING OUT THE INVENTION

[0093] Hereinafter, the present invention will be described in detail.

[0094] However, the following examples are merely for illustrating the present invention and are not intended to limit the scope of the present invention.

[0095] <Methods>

[0096] 1. ALS Patient Recruitment and Clinical Trial Protocol Approval

[0097] Stem cells were induced using patient skin tissues in sporadic ALS patients and patients with genetic mutations, which meet the diagnosis criteria of ALS based on El Escorial Criteria (revised) among amyotrophic lateral sclerosis patients. Such a method was approved based on the IRB research application No. HYUH 2011-08-010-007 of Hanyang University Hospital.

[0098] 2. Measurement of Blood Sphingolipids

[0099] As for extraction and quantification of the sphingomyelin, ceramide, and sphingosine, the lipids were extracted from a serum sample, and the dried lipid extract was resuspended in 25 l of 0.2% Igepal CA-630 (Sigma-Aldrich), and respective lipid levels were quantified using the UPLC system.

[0100] 3. Measurement of ASM and Acid Ceramide (AC) Activity

[0101] Several microliters of serum samples and 3 l of induced neuron samples from ALS patients (FUS, SOD1, TBK1) were mixed with an ASM or AC activity buffer, and stored at 37 C. The samples were prepared by stopping a hydrolysis reaction through the addition of 114 l of ethanol, followed by centrifugation. After 30 l of the prepared samples were transferred into glass vials, 5 l was applied to the UPLC system.

[0102] 4. Neuron Differentiation

[0103] To overcome restrictions of a cell modeling (patient fibroblast) system commonly used in ALS studies, the present study was conducted using patient induced neuron models suitable for neurodegenerative system disorders. The patient induced neurons were obtained by direct conversion by which fibroblasts are converted into functional neurons through the suppression of the polypyrimidine-tract-binding (PTB) protein. The normal controls and patient induced neurons were infected with PTBP1 lentivirus to suppress PTB protein, and after 15 days, enzymatic activity levels were measured.

Example 1

[0104] Measurement of Sphingolipid Levels in Blood

[0105] In order to investigate the effect of amyotrophic lateral sclerosis (ALS) on the sphingolipid metabolism, sphingolipid levels in blood of healthy controls and patients diagnosed with ALS were measured and compared. The patients diagnosed with ALS were confirmed to have mutations of any one gene of FUS (p.Q519E, p.G504Wfs*12, p.R495*), SOD1 (p.I105T, p.G11V), and TBK1 (p.I472Sfs*8, I475T, R384W).

[0106] As can be seen from FIG. 2, no consistent differences were observed between normal controls and ALS patients in view of the levels of analysis target sphingolipids, including sphingomyelin, ceramide, and sphingosine, measured in plasma. There were no significant differences in the levels of sphingomyelin and sphingosine in blood between normal controls and ALS patients. In the case of ceramide, ALS patients with FUS gene mutations showed relatively high levels compared with normal controls, while there was no significant difference among all the ALS patients. No significant changes were shown in the levels of sphingolipids in blood between healthy controls and ALS patients.

Example 2

[0107] Measurement of Acid Sphingomyelinase and Acid Ceramidase Activity in Blood

[0108] In order to investigate the effect of amyotrophic lateral sclerosis (ALS) on the sphingolipid metabolism, the activity levels of sphingolipid-related enzymes in blood of healthy controls and patients diagnosed with ALS were measured and compared.

[0109] The activity of sphingolipid-related enzymes, i.e., acid sphingomyelinase (ASM) that breaks down sphingomyelin into ceramide and phosphorylcholine and acid ceramidase (AC) that breaks down ceramide into sphingosine and fatty acid, was measured. The sphingolipid metabolism and main enzymes involved therein are shown in FIG. 1.

[0110] As can be seen from FIG. 3, it was found that the ASM activity measured in plasma was increased in all the ALS patient groups compared with normal controls. The ASM activity in the ALS patient groups showed consistent and statistically significant differences compared with normal controls, regardless of the type of ALS-related gene. In contrast, the AC activity measured in plasma showed no significant difference between normal controls and ALS patient groups. There was no difference in sphingolipids and the activity level of AC between normal controls and ALS patients, but the activity level of ASM was specifically significantly increased in ALS patients, indicating that the activity level of ASM can be used as a marker for diagnosing ALS.

Example 3

[0111] Measurement of Acid Sphingomyelinase Activity in Induced Neurons

[0112] It was investigated whether an increase in ASM activity confirmed in blood of ALS patients was also observed in induced neurons. Fibroblasts collected from healthy controls and ALS patients were allowed to differentiate into neurons, and the activity of ASM was investigated in the differentiated (induced) neurons.

[0113] As shown in FIG. 4, the activity of ASM was measured to be higher in the induced neurons from the ALS patients than in those from the normal controls, and thus showed similar changes to those observed in plasma. These results suggest that the activity level of ASM can be used as a marker for diagnosing ALS through the measurement of a change in the activity level of ASM.

INDUSTRIAL APPLICABILITY

[0114] The compositions and methods according to the present invention can facilitate the development of novel and effective diagnostic reagents capable of easily diagnosing amyotrophic lateral sclerosis.