CN113009130B

CN113009130B - Biomarker for diagnosing primary sicca syndrome and application thereof

Info

Publication number: CN113009130B
Application number: CN202110185240.3A
Authority: CN
Inventors: 胡朝军; 曾小莉; 李晞; 唐诗逸; 李斯亭; 李梦涛; 曾小峰
Original assignee: Peking Union Medical College Hospital Chinese Academy of Medical Sciences
Current assignee: Peking Union Medical College Hospital Chinese Academy of Medical Sciences
Priority date: 2021-02-10
Filing date: 2021-02-10
Publication date: 2022-08-23
Anticipated expiration: 2041-02-10
Also published as: CN113009130A

Abstract

The invention adopts a lectin microarray containing 56 lectins to detect the glycan profile of the specific binding of serum IgG and the lectin of a patient with Primary Sicca Syndrome (PSS). The results show that the levels of LCA lectin-bound glycans were elevated in PSS patients compared to Primary Biliary Cholangitis (PBC) and healthy controls. Since LCA lectin is specifically binding fucose, this suggests that expression of fucose levels is elevated in PSS patients. Lectin immunoblot validation results showed that LCA lectin-bound glycan content was still elevated in PSS patients. It can be seen that LCA lectin-binding glycan levels in serum IgG can be used as a marker for Primary Sjogren Syndrome (PSS).

Description

Biomarker for diagnosing primary sicca syndrome and application thereof

Technical Field

The invention belongs to the field of biological detection, and particularly relates to a biomarker for diagnosing primary sicca syndrome and application thereof.

Background

Primary Sjogren's Syndrome (PSS) is a complex heterogeneous autoimmune disease characterized by a wide range of clinical manifestations, including Sjogren's Syndrome caused by chronic inflammation of the exocrine glands (mainly lymphocytic infiltration of the lacrimal and salivary glands and resulting in dryness of the eye or/and mouth) to systemic multi-organ involvement, possibly progressing to non-hodgkin's lymphoma mucosa-associated lymphoid disease. Scientists have proposed a variety of biomarkers for PSS diagnosis over the years. However, there is still an urgent need for new specific biomarkers that can improve the diagnosis of disease and the management of PSS patients. Indeed, delays in diagnosis from the onset of symptoms and PSS remain common, and diagnosis still relies on invasive surgery, such as a biopsy of the minor salivary gland. Thus, if one could recognize early stage PSS from serum markers of patients with PSS, one would enable clinicians to treat them more aggressively, thereby preventing adverse consequences and compromising emergency.

IgG is the most abundant antibody in the human body. It participates in a variety of humoral immune processes: antigen neutralization, complement activation and Complement Dependent Cytotoxicity (CDC), antibody dependent cell mediated cytotoxicity (ADCC), and hypersensitivity reactions. Polysaccharides are complex oligosaccharides composed of up to 15 monosaccharide residues, accounting for about 15% by weight of IgG, and are an integral part of IgG, and changes in their composition can affect the structural stability, conformation and half-life of IgG, as well as its effector functions. In fact, complete removal of the polysaccharide results in loss of both the pro-inflammatory and anti-inflammatory activities of IgG. Since the discovery of aberrant changes in IgG glycosylation in rheumatoid arthritis patients, there has been increasing evidence that IgG glycosylation plays a significant role in autoimmune diseases. The research aims to detect the serum IgG glycan profile of the patient with the anti-PSS through a high-flux glycosylation analysis technology, namely a lectin microarray technology, and provides preparation for exploring a new PSS diagnosis biomarker.

Disclosure of Invention

In order to solve the above problems, the present invention provides a biomarker for diagnosing primary sjogren's syndrome and uses thereof.

First, the present invention provides a biomarker for diagnosing primary sjogren's syndrome, which is a complex formed by binding of LCA lectin to IgG.

Wherein said IgG comprises fucose.

Secondly, the invention also provides the use of the biomarker for preparing a reagent for diagnosing primary sjogren syndrome.

Specifically, the diagnosis includes: determining the level of a complex formed by binding of LCA lectin to IgG in a biological sample obtained from a patient exhibiting an IgG-related disease; optionally, the step of (a) is carried out,

comparing the level of the complex formed by binding of LCA lectin to IgG in the biological sample to control data, wherein a detectably increased level of the complex formed by binding of LCA lectin to IgG in the sample relative to the control data is indicative of a likelihood of developing primary sjogren syndrome.

Wherein the biological sample is a serum sample.

The invention also provides the use of LCA lectin in the manufacture of a medicament for the diagnosis of primary sjogren syndrome.

Wherein the diagnosing comprises: contacting LCA lectin with a biological sample obtained from a patient presenting primary sjogren's syndrome and determining the level of complex formed by LCA lectin binding to IgG; optionally, the step of (a) is carried out,

comparing the level of the complex formed by the binding of LCA lectin to IgG in the biological sample to control data, wherein a detectably increased level of the complex formed by LCA lectin to IgG binding in the sample relative to the control data indicates a likelihood of primary sjogren syndrome.

Wherein the biological sample is a serum sample.

In a specific embodiment of the invention, the level of the complex formed by the binding of LCA lectin to IgG is measured by the steps comprising:

a. contacting a biological sample from a patient with LCA lectin;

b. forming a lectin-glycan complex between IgG and LCA lectin present in the biological sample;

c. washing to remove any unbound IgG;

d. adding a detection antibody that is labeled and reactive with an antibody from the biological sample;

e. washing to remove any unbound labeled detection antibody; and

f. converting the label of the detection antibody into a detectable signal.

Wherein said LCA lectin is deposited or immobilized on a solid surface support.

The solid phase surface carrier is preferably in the form of latex beads, porous plates or membrane strips, nano-tubes, flakes with two-dimensional codes and the like.

Wherein the detection antibody is labeled by covalent attachment to an enzyme, a label with a fluorescent compound or a metal, or a label with a chemiluminescent compound.

The invention detects the glycan profile of specific combination of serum IgG of a PSS patient and agglutinin by adopting a agglutinin microarray containing 56 agglutinin. The results show that the levels of LCA lectin-bound glycans were elevated in PSS patients compared to Primary Biliary Cholangitis (PBC) and healthy controls. Since LCA lectin is specifically binding fucose, this suggests that expression of fucose levels is elevated in PSS patients. To confirm the reliability of this result, the present invention also uses lectin immunoblot validation results. The results show that LCA lectin-bound glycan content remains elevated in PSS patients, consistent with the results of the lectin microarray. The results show that: LCA lectin-binding glycan levels in serum IgG served as markers of Primary Sjogren Syndrome (PSS).

Drawings

FIG. 1A: the whole lectin chip; 1B: chip microarray of 56 kinds of agglutinin; 1C: fluorescence intensity of Cy 5-labeled IgG antibody reacted with lectin.

FIG. 2 shows specific binding signal-to-noise ratios of serum IgG and lectin LCA in lectin chip detection PSS, PBC and NC. P < 0.05.

FIG. 3 shows a lectin LCA immunoblot.

FIG. 4 shows lectin blot detection PSS, PBC and NC serum IgG specific binding strength to lectin LCA. P < 0.01.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Example 1 lectin microarray analysis of serum IgG glycosylation

Experimental specimen: the study included three groups of people: PSS group (40 PSS patients), PBC group (50 PBC disease controls), NC group (38 physical examination subjects), as detailed in table 1. Wherein the diagnosis of the PSS group and the diagnosis of the PBC group both meet the diagnosis standard of the corresponding diseases. All the people who entered the group collected fresh blood, and immediately separated serum, and frozen at-80 ℃ for later use.

TABLE 1 PSS chip Experimental study basic conditions

Grouping	Number of examples	Male/female	Age range	Mean age
					PSS
	40	1/9	31-68	48.52±9.73
					PBC	50	2/23	34-75	52.30±10.13
Healthy control group	38	3/35	35-70	45.60±7.64

A lectin microarray containing 56 lectins was used to detect the glycosylation state in the test specimen. Lectin can be specifically combined with glycan molecules at the tail end of glycoprotein to form a complex, and the type and content of glycan on the surface of target protein can be researched through the specific combination of different lectins and the glycan. Lectin microarrays are now being used more and more extensively in glycosylation studies due to their high efficiency. The study used 14 lectin microarrays per lectin chip, and the lectin microarray contained 56 lectins, each immobilized in triplicate in the array. Then, the diluted serum samples were added to the lectin microarray, reacted therewith, and then added with Cy 5-labeled IgG antibody, and a signal value of each lectin with IgG-specific binding glycan, which correlates with binding affinity and binding strength, was obtained, as shown in fig. 1.

After equilibrating the frozen samples at room temperature, each sample serum was diluted 1:200 and added to the microarray and incubated overnight at 4 ℃. Then, the Cy 5-labeled IgG antibody was hybridized with the lectin in the microarray for 1 hour in a light-shielded environment. The fluorescence intensity of all lectins was analyzed independently. And converts the chip image to a digital format for analysis. The signal-to-noise ratio (S/N) for each lectin spot was calculated using the signal-to-noise ratio (difference between foreground and background values for the spot) for each lectin spot. To prevent bias of lectin microarrays between arrays, we normalized the S/N data using normalization between arrays. Significant differences in lectin binding capacity were determined by the distribution of data among groups according to the following rules (1) comparison between groups ≧ 1.3 or < 0.767; (2) and (4) comparing the test types among the groups, if the test types accord with normality, selecting T test, and if the test types do not accord with normality, selecting nonparametric test, wherein the P value is less than 0.05.

The results are shown in tables 2 and 3. The S/N data show significant differential changes in the PSS group versus IgG glycosylation from the PBC and NC groups: (1) PSS patient serum IgG bound less to lectin SSA compared to PBC group, in contrast to increased binding to lectins LCA, MNA-M and ACL (P all < 0.05); (2) (iii) reduced binding of serum IgG of PSS patients to the lectins PHA-E and PHA-L compared to the NC group; in contrast, binding to lectins LCA and MNA-M was increased (P < 0.05); (3) PSS patients have increased binding of serum IgG to lectins LCA and MNA-M (both P <0.05) compared to PBC and NC groups together. FIG. 2 shows the comparison of LCA lectin signal values of the PSS, PBC and NC groups.

TABLE 2 PSS chip results

*P<0.05,**P<0.01

TABLE 3 PSS lectin and corresponding glycan binding specificity

The results indicate that serum IgG and LCA lectin binding glycan levels are specific biomarkers for Primary Sjogren Syndrome (PSS) relative to PBC patients and normal healthy populations.

Example 2 serolectin imprinting validation experiment

Experimental specimens and methods: in order to further clarify the reliability of the above lectin microarray detection findings, lectin blot analyses were performed on PSS specimens, PBC and NC specimens of the same lot (12 specimens, respectively) and samples of a new lot (16 specimens, respectively) grouped in the same way using the lectin microarray, and the basic data of the subjects to be verified are shown in table 4.

TABLE 4 basic data of verification object

Serum specimen 1: 100, adding a sample buffer solution, mixing, boiling at 100 ℃ for 5 minutes, performing SDS-PAGE electrophoresis in 10% preformed gel, and electrically transferring proteins in the preformed gel to a PVDF membrane. And (3) sealing the PVDF film which is successfully transferred, hybridizing the PVDF film with the lectin marked by cy3, and finally detecting a fluorescence signal by a fluorescence imager. The intensity of the fluorescence signal is proportional to the binding force of the lectin-bound glycoprotein glycosyl groups.

As a result: results were compared by LCA lectin blotting of the same lot and a new lot of patient specimens (28 total) on the lectin chip. Immunoblot of serum IgG and LCA lectin (figure 3), PSS patient serum IgG binding to lectin LCA was significantly elevated (both P <0.05) compared to DC and NC by ImagJ software banding grayscale analysis (figure 4). This indicates that LCA lectin-bound glycan, fucose levels, are abnormal in PSS patient serum IgG.

And (4) conclusion: the lectin blot validation results were consistent with the lectin chip detection results, with serum IgG LCA lectin binding glycan levels as a biomarker for Primary Sjogren Syndrome (PSS) relative to PBC patients and normal healthy populations.

Claims

Use of LCA lectin in the manufacture of a reagent for the diagnosis of primary sjogren syndrome by contacting LCA lectin with fucosylated IgG in a biological sample obtained from a patient presenting primary sjogren syndrome and determining the level of complex formed by binding of LCA lectin to IgG.
2. The use of claim 1, wherein said diagnosing comprises:

comparing the level of complexes formed by binding of LCA lectin to IgG in the biological sample to control data, wherein the level of complexes formed by binding of LCA lectin to fucosylated IgG is increased in a sample of a patient with primary sjogren syndrome relative to the control data.
3. Use according to claim 1 or 2, wherein the biological sample is a serum sample.
4. The use according to claim 1 or 2, wherein the level of complexes formed by the binding of LCA lectin to fucosylated IgG is measured by the steps comprising:

a. contacting a biological sample from a patient with LCA lectin;

b. forming lectin-glycan complexes between fucosylated IgG present in the biological sample and LCA lectins;

c. washing to remove any unbound fucosylated IgG;

d. adding a labeled detection antibody that binds to fucosylated IgG;

e. washing to remove any unbound labeled detection antibody; and

f. converting the label of the detection antibody to a detectable signal.
5. The use according to claim 4, wherein the LCA lectin is deposited or immobilized on a solid surface support.
6. The use of claim 5, wherein the solid surface support is in the form of latex beads, porous plates or membrane strips, nanotubes, flakes with two-dimensional codes.
7. The use of claim 4, wherein the detection antibody is labeled by covalent attachment to an enzyme, a label with a fluorescent compound or metal, or a label with a chemiluminescent compound.