KR20040006404A - Protein for diagnosing diabetic retinopathy - Google Patents

Abstract

PURPOSE: A protein for diagnosing diabetic retinopathy is provided, thereby easily and accurately detecting apolipoprotein J protein of which amount is decreased in a patient suffering from diabetic retinopathy. CONSTITUTION: An apolipoprotein J protein having the amino acid sequence of SEQ ID NO: 1 useful for diagnosis of diabetic retinopathy or peptide fragments thereof are provided, wherein the peptide fragments comprise a peptide having the amino acid sequence of SEQ ID NO: 2. An antibody binding to the protein of SEQ ID NO: 1 or the peptide fragment thereof is provided. A kit for the diagnosis of diabetic retinopathy comprises the antibody against the protein of SEQ ID NO: 1, wherein the kit further comprises an antigen which is labeled with apolipoprotein J protein by using peroxidase, alkalinephosphatase or biotin.

Description

Protein for Diagnosing Diabetic Retinopathy {Protein for Diagnosing Diabetic Retinopathy}

The present invention relates to a protein for diagnosing diabetic retinopathy, and more specifically, apolipoprotein J is reduced in the diabetic retinopathy from the fact that compared to the normal vitreous, confirming that the change in this protein in the blood and using the same The present invention relates to a diagnostic protein for diabetic retinopathy completed by an immunological method, a diagnostic kit thereof, and a diagnostic method thereof.

Diabetes is a complex metabolic disease that causes lesions in the microvascular system, causing a wide range of disorders in systemic tissues including the eye, and is the most important systemic disease affecting the eye (Lee Tae-hee, Choi Young-gil, Diabetic vascular complications , Seoul: Korea Medical University). (1993)). Among them, diabetic retinopathy is one of the most serious complications, and it has become an important problem as the life expectancy and length of disease of diabetic patients are prolonged due to improvement of living standard and treatment level (Klein R. et al , Arch Ophthalmol. 102: 520-532 (1984)). Diabetic retinopathy is divided into non-proliferative diabetic retinopathy, in which retinal lesions due to vascular disorders are localized in the retina, and proliferative diabetic retinopathy, in which neovascular tissue grows from the retina to the vitreous cavity (Green, In: Spencer WH, ed.Ophthalmic Pathology: an atlas and textbook.4th ed.Philadelphia: WB Saunder; 1124-1129 (1996)). Diagnosis of diabetic retinopathy is made by observing characteristic structural changes in the fundus. Visual damage due to diabetic retinopathy is due to vitreous hemorrhage in proliferative diabetic retinopathy and macular degeneration along with tractional retinal detachment of the macular. This is well known for the effectiveness of laser treatment along with surgical treatment (Diabetic Retinopathy Study Report Number 14: photocoagulation treatment of diabetic retinopathy.Int Ophthalmol Clin. 27: 239-253 (1987)). This treatment can be done at an appropriate stage to prevent vision loss with minimal side effects. Therefore, diabetic retinopathy and diagnostic efforts should be made through frequent tests to determine whether or not the stage of surgical treatment has already been reached. However, until now, only the examination by fundus photography performed in ophthalmology as a diagnostic method is possible. Therefore, due to the difficulty of early diagnosis, often miss the timing of prevention and surgery. Therefore, the present invention has devised a method that can be easily diagnosed in the blood. At present, there is no diagnostic method for diabetic retinopathy through blood, and the present inventors used proteomics to find proteins with changes in blood and apply them to diagnosis. The protein has been shown to be quantitatively changed in patients with diabetes alone and diabetic complications, and thus the invention has been completed using accurate quantification by immunological methods.

The present invention solves the above problems, and the object of the present invention is to provide a protein that can easily quantify the group of proteins associated with diabetic retinopathy in the blood.

Another object of the present invention is to provide a kit using an immunological method using the protein.

Figure 1 is a schematic of the ocular vitreous pretreatment for application to proteomics.

Figure 2 shows the gel photograph of the CBB staining the ocular vitreous protein after two-dimensional electrophoresis. The arrowed area shows excess protein in normal vitreous but reduced protein in diabetic retinopathy vitreous.

FIG. 3 is a peptide mass spectrum diagram of the protein of the arrow region of FIG. 2 digested with trypsin and analyzed by MALDI-TOF mass spectrometer. FIG.

4 is an amino acid analysis of one trypsinized peptide of the protein of the arrow region of Figure 2 using a Q-TOF analyzer.

5 is a photograph showing the results of Western blotting using anti-apolipoprotein J antibody. The confirmed serum was negatively treated with Blue-sepharose and protein A column before Western blotting. The numbers on this photo are as follows:

1: Serum protein from patients with only 2ug of diabetes

2: Serum Proteins from 2ug Proliferative Diabetic Retinopathy

3: Serum Protein from 2ug of Non-proliferative Diabetic Retinopathy

4: 2 ug of normal serum protein

In order to achieve the above object, the present invention provides a peptide fragment of the apolipoprotein protein comprising the apolipoprotein J protein of SEQ ID NO: 1 and SEQ ID NO: 2 effective for diagnosing diabetic retinopathy.

In addition, the present invention provides an antibody that binds to the above protein, wherein the antibody is preferably polyclonal or monoclonal, but more preferably monoclonal antibody.

The present invention also provides a kit for diagnosing diabetic retinopathy comprising the above antibody.

The kit of the present invention further comprises an antigen labeled Apolipoprotein J protein with enzyme peroxidase, alkaline phosphate or biotin.

In another aspect, the present invention comprises the steps of treating the antibody with apolipoprotein J label protein labeled with a vitreous or blood sample and peroxidase, alkaline phosphate or biotin; And by measuring the absorbance of the complex provides a method for diagnosing diabetic retinopathy when showing a higher absorbance (lower ELISA value) than normal.

In other words, the present invention is based on the competition between the apolipoprotein J protein of the sample to be tested against the antibody against the apolipoprotein J protein and the apolipoprotein J-labeled protein labeled with peroxidase, alkaline phosphate or biotin. If the amount of apolipoprotein J protein in the sample is low, the high absorbance (low ELISA value) is used to diagnose diabetic retinopathy.

The present invention also provides an apolipoprotein J gene comprising SEQ ID NO: 3 and a fragment thereof SEQ ID NO: 4 encoding the apolipoprotein J protein.

The present invention will be described in detail.

The present invention first analyzed the protein group having a special change in diabetic retinopathy by proteomics method. By analyzing protein types and quantitative changes of vitreous changes in normal and diabetic retinopathy patients, the following novel phenomena were identified, and the appropriate protein changes were identified in the blood and applied as an appropriate immunological method for diagnosis of diabetic retinopathy. Diagnosis kits were prepared: First, the intraocular vitreous was collected from diabetic patients and diabetic retinopathy patients with normal persons as a control group to obtain a protein group showing qualitative and quantitative differences through two-dimensional gel separation and image analysis. MALDI mass spectrometer and Q-TOF analyzer were used to identify group identity. The protein whose change was observed and confirmed was apolipoprotein J. In the vitreous of diabetic retinopathy, an excess of apolipoprotein J observed in the normal vitreous was observed. There are no reports of apolipoprotein J reduction in diabetic retinopathy. ; Second, this quantitative change showed a quantitative change in the blood. Apolipoprotein J decreased in the blood of diabetic retinopathy when diabetic blood was used as a control. This result has not been reported yet; Third, the abundance level of the protein was adopted by making a kit through an immunological method, which was easy to use, sensitive and high in accuracy.

Hereinafter, the present invention will be described in more detail with reference to non-limiting examples.

Example 1 Ocular Vitreous Samples for Proteomic Analysis

Diabetic retinopathy is one of the complications of long-term diabetes. This disease causes a lot of neovascularization with an incomplete vascular structure, causing bleeding in the intraocular vitreous, causing abnormalities in the retina, depending on the degree of vision and loss of vision. In the present invention, through the protein analysis of the normal control group and diabetic retinopathy patients, the disease-causing factor was searched and the information about the protein representing the disease state was achieved by the diagnosis. Protein analysis uses the latest proteomics method. First, the ocular vitreous was easily processed for application to proteomic methods . The vitreous contains an excess of hyaluronic acid, a high molecular sugar. However, the sugar was found to have a significant adverse effect on protein isolation. Therefore, a method for effectively removing it was devised (see FIG. 1). In this method, 4 ml of vitreous is diluted with 16 ml of distilled water and placed in a tube with 1,000,000 cut off membrane. Centrifugation is carried out for 2 hours at 8,000 rpm at 4 ° for 2 hours, and the process is repeated three times. Filtered using the difference. Unbound protein was concentrated in a tube with 10,000 cut-off membrane by centrifugation at 4,000 rpm at 4 ?? and then used for analysis. The method of removing the high molecular sugars solved the problem of poor separation at low pH, thus enabling a very effective analysis.

Example 2 Investigation of Intraocular Changed Protein Group in Normal and Diabetic Retinopathy

In each vitreous, only protein was concentrated and 1 mg of protein was used for analysis. The procedure was first separated two-dimensionally by a separation method using two different properties. One was protein transfer properties (IEF) (pH 3-10) according to pH, and the other (polyacrylamide 8-18%) protein transfer was performed according to molecular weight. Protein transfer according to pH was carried out for 12 hours at a current of 50mA per gel and then electrophoresed at 50mA per gel for 6 hours in polyacrylamide. This transferred protein was stained with a Coomassie Brillant Blue (CBB) staining agent to confirm its presence, and then, using a computer image analysis software Phoretix (Nonlinear dynamics, UK), the difference between the protein in normal people and the vitreous protein in diabetic retinopathy patients The analysis was carried out. As a result of analyzing the proteins of the two groups, there was a protein group showing a difference (see FIG. 2).

Example 3 Identification of Different Existing Proteins in Normal Persons and Diabetic Retinopathy

The protein was identified by the MALDI-TOF mass spectrometer (see FIG. 3) and the Q-TOF analyzer in order to find a protein having a quantitative or qualitative difference (see FIG. 4). This led to a decrease in the amount of apolipoprotein J in diabetic retinopathy.

Example 4 Western Blotting for Apolipoprotein J in Blood

Electrophoresis was performed on polyacrylamide gels for each serum to determine changes in the presence and amount of apolipoprotein J in the blood of patients with diabetes alone and patients with diabetic retinopathy. Proteins were transferred to the membrane and western blotting was performed using anti-apolipoprotein J protein single antibody (Santa Cruz Biotechnology, USA). At this time, the membrane was sufficiently reacted with PBS solution containing 5% of skim milk for 30 minutes for adhesion only to proteins having specificity, and then reacted with the primary antibody mentioned above at room temperature for at least 1 hour. Membranes were washed three times for 10 min each with PBST solution (PBS + 0.5% Tween20) to remove unattached antibodies. The washed membrane was shaken for 1 hour with a mixture of PBS solution containing an appropriately diluted and peroxidase enzyme-attached antimouse antibody (Axell Accurate, USA) and 5% skim milk. After washing the membrane with PBST solution three times for 10 minutes, the protein bands were identified at the expected location using the ECL coloration method, and compared to normal patients and diabetic retinopathy (NPDR) patients with diabetes only. Apolipoprotein J protein bands were found to be weak in patients (proliferative diabetic retinopathy: PDR) (see FIG. 5).

Example 5 : Diagnostic Study Coating Antibody Against Human Apolipoprotein J on a 96-Pole Plate and Comprising Enzyme-labeled Apolipoprotein J

This study was performed to determine whether the serum of diabetic retinopathy among diabetic patients could be identified by ELISA using apolipoprotein J labeled with peroxidase enzyme. Serum from 10 patients with diabetic retinopathy and 10 controls from diabetic patients without diabetic retinopathy were used. First, 100 μl of anti-apolipoprotein J (1 ug of antibody protein per well) dissolved in a coating buffer (50 mM NaHCO ₃ , pH9.0) at a concentration of 10 ug / ml was prepared in an EIA 96-hole plate at room temperature for 1 hour. The reaction was coated and washed twice with 400ul of PBST for 10 minutes each, followed by post-coating with PBS containing 1% BSA. 50ul of patient's serum diluted with PBST buffer and 50ul of apolipoprotein J-labeled protein with peroxidase were reacted at room temperature for 1 hour. Wash this again three times with PBST buffer and add 100ul of 0.1M citrate-phosphate buffer (pH4.9) containing 1mg / ml OPD (o-phenylenediamine polyhydrochloride) and 0.03% H ₂ O ₂ at room temperature. After 20-30 minutes, 100ul of 3M sulfuric acid was added to stop the reaction, and the absorbance was measured at 490 nm using an ELISA reader. The absorbance was converted into a standard titration curve and the dilution factor was used to determine the amount of apolipoprotein J per unit volume of blood (ml). The results are shown in Table 1. Serum apolipoprotein J in patients with diabetes alone was 0.72-1.5 mg / ml, 0.4 mg / ml or less (60%), 0.4-0.7 mg / ml (20%) 0.7 mg / ml for diabetic retinopathy. Above (20%). When the ELISA value is less than 0.7 mg / ml, it can be said that the accuracy of about 80% is accurate if it is positive for diabetic retinopathy.

TABLE 1 Reactivity Study with Apolipoprotein J in Patient Serum by ELISA

number serum ELISA value mg / ml One Diabetic 1.23 2 Diabetic 1.34 3 Diabetic 1.03 4 Diabetic 1.43 5 Diabetic 0.87 6 Diabetic 1.23 7 Diabetic 0.98 8 Diabetic 0.71 9 Diabetic 1.16 10 Diabetic 1.50 11 Diabetic retinopathy 0.25 12 Diabetic retinopathy 0.45 13 Diabetic retinopathy 0.15 14 Diabetic retinopathy 0.35 15 Diabetic retinopathy 0.23 16 Diabetic retinopathy 0.78 17 Diabetic retinopathy 0.48 18 Diabetic retinopathy 0.81 19 Diabetic retinopathy 0.28 20 Diabetic retinopathy 0.32

The present invention is a technology that can easily diagnose diabetic retinopathy, a complication of diabetes. To date, there are no commercially available effective diagnostic agents for diabetic retinopathy. Diagnosis of diabetic retinopathy was entirely visited by a hospital and examined by an ophthalmologist. Therefore, early diagnosis is not possible if diabetics do not feel abnormal vision due to subjective symptoms and do not undergo regular eye examination. Since the development of this diagnostic agent is characterized by a simple blood test, it is very useful in that the complications can be checked before the ophthalmologic examination. In particular, the present invention adopts an ELISA method using 96 holes, which can be examined in large quantities, and thus, it is inexpensive and easy to handle for a large number of diabetic patients who visit a medical examination or a medical department. As the immunological method is used, the accuracy and precision are excellent. In conclusion, the present invention is useful for early diagnosis and screening in diabetic retinopathy, and will improve the effect of diabetic retinopathy by helping to determine the time of administration of the therapeutic agent in patients with potential diabetic retinopathy.

Claims (7)

The apolipoprotein J protein or a peptide fragment thereof according to SEQ ID NO: 1 effective for diagnosing diabetic retinopathy. The method of claim 1, Wherein said fragment comprises a peptide of SEQ ID NO: 2. An antibody that binds to the protein of claim 1 or a fragment thereof. A diagnostic kit for diabetic retinopathy comprising the antibody of claim 3. The method of claim 4, wherein The kit is a diagnostic kit for diabetic retinopathy, characterized in that it further comprises an antigen labeled with apolipoprotein J protein with enzyme peroxidase, alkaline phosphate or biotin. a) treating the antibody of claim 3 with an apolipoprotein J labeled protein attached to the vitreous or blood sample with peroxidase, alkaline phosphate or biotin; And b) A method for diagnosing diabetic retinopathy when the ELISA value of the complex is lower than normal. The nucleotide of SEQ ID NO: 4 encoding the apolipoprotein J gene of SEQ ID NO: 3 encoding the protein of claim 1 or the peptide of SEQ ID NO: 2 of claim 2.