Application of ceacam21 in diagnosis of membranous nephropathy

Abstract

The application relates to the technical field of disease diagnosis, and particularly relates to application of CEACAM21 as a serum marker in diagnosis of membranous nephropathy. Based on the marker, risk stratification and treatment decision of the membranous nephropathy can be carried out, and the application has significant clinical significance.

Description

Technical Field

[0001] This invention relates to the field of molecular diagnostics, specifically to the application of CEACAM21 as a serum biomarker in the diagnosis of membranous nephropathy and the preparation of corresponding diagnostic products. Background Technology

[0002] Membranous nephropathy (MN), a kidney-specific autoimmune disease, has long been one of the most common pathological types of nephrotic syndrome in adults. Its core pathological mechanism involves the generation of autoantibodies against podocyte antigens (such as PLA2R and THSD7A), leading to the in situ formation and deposition of immune complexes on the epithelial side of the glomerular basement membrane. This, in turn, activates the complement system, causing podocyte cytoskeleton disruption, foot process fusion, and slit diaphragm damage. Epidemiological data show that the proportion of MN in primary glomerular diseases has increased significantly in recent years and is showing a trend towards affecting younger individuals, placing a heavy burden on the public health system.

[0003] Currently, clinical treatment of membranous nephropathy (MN) faces challenges in treatment decisions and is hampered by outdated and limited diagnostic indicators. In terms of clinical treatment decisions, the natural course of MN exhibits extreme heterogeneity. Approximately 30%-40% of patients present with a "benign course," meaning they have only mild proteinuria or can achieve spontaneous remission with conservative treatment (RAS blockers). However, another 30%-40% of patients are in a "progressive" stage, which, without timely intervention, leads to persistent massive proteinuria, uncorrectable hypoalbuminemia, and thromboembolic complications, ultimately progressing to end-stage renal disease (ESRD) within 5-15 years. Currently, the 2021 guidelines of the Kidney Disease for Improvement Globally (KDIGO) recommend a "tiered management" strategy, which involves differentiated treatment for patients at different risk levels. For high-risk patients, immunosuppressive regimens, including alkylating agents (such as cyclophosphamide), glucocorticoids, calcineurin inhibitors (CNIs), or anti-CD20 monoclonal antibodies (rituximab), are recommended. However, these drugs are all double-edged swords: alkylating agents carry the risks of cumulative myelosuppression, reproductive toxicity, and carcinogenesis; long-term use of hormones can lead to metabolic disorders and infections; and while rituximab is well-tolerated, it is expensive and has secondary failure issues in some patients. Therefore, "when to initiate immunotherapy" and "how to accurately select the beneficiaries" have become the biggest challenges for clinicians.

[0004] In clinical diagnosis, doctors currently rely primarily on traditional nonspecific indicators to assess the condition, including 24-hour urine protein quantification, serum albumin levels, and estimated glomerular filtration rate (eGFR). However, these indicators have significant limitations: 1) Significant lag effect of proteinuria: Proteinuria is a downstream consequence of damage to the glomerular filtration barrier, rather than a real-time reflection of immune inflammatory activity. Proteinuria may not peak for weeks or even months after an immune response has occurred or even caused tissue damage; conversely, even if the immune response ceases, the repair process of the damaged basement membrane is lengthy, and a time lag between "immune remission" and "clinical remission" may persist. 2) Insufficient specific antibodies: Although the discovery of anti-PLA2R antibodies was a milestone in MN diagnosis, approximately 20%-30% of MN patients are PLA2R negative. Furthermore, antibody titers do not perfectly parallel clinical phenotypes (severity of proteinuria) in some patients, especially during the early "immune active phase" of the disease, when antibodies may have already deposited in the kidneys but serum levels are low, leading to an underestimation of the condition. 3) Risks of the “observation period”: Due to the insensitivity of the above indicators, guidelines usually recommend a 3-6 month “observation period” for patients to determine whether there is a tendency for spontaneous remission. However, for high-risk patients in the occult progression stage, this 6-month wait may mean missing the best “time window” to reverse podocyte damage, leading to irreversible nephron sclerosis.

[0005] Therefore, finding a novel serum biomarker that can directly reflect the body's immune inflammatory activation state before the formation of large amounts of proteinuria is of great significance for breaking the deadlock of "blindly waiting" and achieving early and precise intervention in proteinuria (MN). In view of this, this invention is proposed. Invention Overview To address current clinical challenges, this invention, through dedicated research, has discovered that carcinoembryonic antigen-associated cell adhesion molecule 21 (CEACAM21) exhibits specific high expression in the serum of high-risk membranous nephropathy (MN) patients. Validation has demonstrated that it can serve as a molecular marker for stratified diagnosis of membranous nephropathy. CEACAM21 belongs to the CEA cell adhesion molecule family, whose members (such as CEACAM1, CEACAM5 / 6) are known to play crucial roles in intercellular interactions, leukocyte transendothelial migration, and immune synapse formation. While previous studies have largely focused on the role of CEACAM21 in tumor invasion such as prostate cancer, or the signaling pathways (e.g., pAKT / SOX9 axis) of its family members in environmental toxin-induced renal tubular damage, the role of CEACAM21 in autoimmune glomerular diseases has remained undiscovered. This invention reveals that CEACAM21 can act as an early mediator of endothelial or immune cell stress responses induced by immune complex deposition, with its serum level rising earlier than the onset of severe proteinuria. Compared to traditional indicators, CEACAM21 can more sensitively detect the microscopic inflammatory state in the kidneys, thus effectively distinguishing between "low-risk individuals capable of self-healing" and "high-risk individuals requiring immunosuppression / hormonal intervention." This discovery provides a solid material basis for establishing a novel risk assessment system for MN based on molecular pathological mechanisms, and is expected to significantly optimize current clinical treatment pathways.

[0006] Based on the research results of this invention, the following specific technical solution is proposed: This invention first provides the application of CEACAM21 as a biomarker in the diagnosis of kidney disease, or the application of a detection agent for obtaining the level of CEACAM21 in a sample in the preparation of products for membranous nephropathy.

[0007] Furthermore, the kidney disease specifically refers to membranous nephropathy. Even further, the diagnosis includes differentiating MN patients from healthy individuals, or differentiating high-risk MN patients from low-risk MN patients (thereby for stratification of disease severity).

[0008] In some aspects, the product includes, but is not limited to, kit form. In some aspects, CEACAM21 is an independent indication for the diagnosis of membranous nephropathy. In some aspects, the level includes nucleic acid levels or protein levels. In some aspects, the nucleic acid level specifically refers to transcriptomic nucleic acid levels. In some aspects, the nucleic acid level or protein level includes, but is not limited to, the abundance or concentration of nucleic acids or proteins; in some aspects, it may also include, for example, the abundance or concentration of mutations in nucleic acids or proteins.

[0009] Furthermore, the nucleic acid level is obtained through sequencing technology, nucleic acid amplification technology, nucleic acid hybridization technology, electrophoresis technology, biomass spectrometry technology, or chromatography technology. Furthermore, the methods for obtaining the nucleic acid level include, but are not limited to, any of the following: gene sequencing, polymerase chain reaction, isothermal amplification reaction, gene chip method, probe hybridization, gel electrophoresis, RNA blotting, nucleic acid mass spectrometry, or liquid chromatography.

[0010] Furthermore, the protein level is obtained through sequencing, immunoassay, electrophoresis, mass spectrometry, or chromatography. Further, the methods for obtaining the protein level include, but are not limited to, any of the following: amino acid sequencing, enzyme-linked immunosorbent assay (ELISA), chemiluminescence immunoassay, immunochromatography, radioimmunoassay, immunohistochemistry, Western blotting, flow cytometry, gel electrophoresis, proteometry, or liquid chromatography.

[0011] In some aspects, the product also includes a detection reagent for obtaining levels of other biomarkers of membranous nephropathy known in the art, thereby enabling combined detection. In some aspects, the product also includes sample processing reagents, including at least one of sample lysis reagents, sample purification reagents, and sample extraction reagents. In some aspects, the product also includes at least one of standards, calibrators, controls, and buffer solutions. In some aspects, the sample includes tissue, cells, body fluids, serum, plasma, whole blood (peripheral blood), urine, semen, saliva, pleural fluid, ascites, cerebrospinal fluid, feces, or synovial fluid; preferably serum, plasma, or whole blood. In some aspects, the diagnosis includes, but is not limited to, screening, early diagnosis, auxiliary diagnosis, diagnosis, prediction / assessment of disease severity, assessment of disease activity, and monitoring of treatment for membranous nephropathy; preferably, early diagnosis and prediction / assessment of disease severity for membranous nephropathy.

[0012] The present invention also provides a product for diagnosing membranous nephropathy, comprising a detection reagent for obtaining CEACAM21 levels in a sample. Further, the product particularly includes a kit form.

[0013] Similarly, in some respects, CEACAM21 can be used independently as an indication for the diagnosis of membranous nephropathy; and the level may include nucleic acid level or protein level.

[0014] In some aspects, the product also includes a detection reagent for obtaining levels of other biomarkers of membranous nephropathy known in the art, thereby enabling combined detection. In some aspects, the product also includes sample processing reagents, including at least one of sample lysis reagents, sample purification reagents, and sample extraction reagents. In some aspects, the product also includes at least one of standards, calibrators, and controls. In some aspects, the sample includes tissue, cells, body fluids, serum, plasma, whole blood (peripheral blood), urine, semen, saliva, pleural fluid, ascites, cerebrospinal fluid, feces, or synovial fluid; preferably serum, plasma, or whole blood. In some aspects, the diagnosis includes, but is not limited to, screening, early diagnosis, auxiliary diagnosis, diagnosis, prediction / assessment of disease severity, assessment of disease activity, and monitoring of treatment for membranous nephropathy; preferably, early diagnosis and prediction / assessment of disease severity for membranous nephropathy.

[0015] The present invention also provides a method for diagnosing membranous nephropathy in vivo or in vitro, including the step of obtaining CEACAM21 levels in a subject sample.

[0016] In some aspects, the method includes the following steps: (i) Obtain the CEACAM21 level in the subject samples; (ii) Comparison of CEACAM21 levels with control samples; wherein a significant difference in CEACAM21 levels between the subject sample and the control sample is an indication that the subject has membranous nephropathy; or, (ii) Compare with a set absolute threshold; wherein, the subject sample level being higher than the absolute threshold is an indication that the subject has membranous nephropathy.

[0017] In some aspects, CEACAM21 can be used independently as an indication for the diagnosis of membranous nephropathy. In some aspects, the levels include nucleic acid levels or protein levels. In some aspects, the samples include tissues, cells, body fluids, serum, plasma, whole blood (peripheral blood), urine, semen, saliva, pleural effusion, ascites, cerebrospinal fluid, feces, or synovial fluid; preferably serum, plasma, or whole blood. In some aspects, the diagnosis includes, but is not limited to, screening for membranous nephropathy, early diagnosis, auxiliary diagnosis, confirmation, assessment of disease severity, assessment of disease activity, and monitoring of treatment; preferably, the diagnosis is particularly for the early diagnosis and assessment of disease severity in membranous nephropathy. In some aspects, the subjects are preferably human.

[0018] The present invention also provides a method for detecting biomarkers in subjects with or suspected of having membranous nephropathy, either in vivo or in vitro, the method comprising determining or detecting CEACAM21 levels from a sample of the subject. In some aspects, the method may be for disease diagnostic purposes or for non-disease diagnostic purposes.

[0019] The present invention may also provide a method for evaluating or screening diagnostic biomarkers for membranous nephropathy, the method comprising the step of performing a correlation or consistency analysis between a potential biomarker and CEACAM21, and verifying the diagnostic value of the potential biomarker through the conclusion of the correlation or consistency.

[0020] The present invention also provides a method for screening therapeutic agents for membranous nephropathy in vivo or in vitro, the method comprising the step of evaluating the CEACAM21 level of samples treated with the therapeutic agent.

[0021] The present invention also provides a serum biomarker for diagnosing membranous nephropathy, wherein the serum biomarker is CEACAM21.

[0022] The present invention also provides a treatment method for membranous nephropathy, the treatment method comprising the steps of assessing the CEACAM21 level of the subject, stratifying membranous nephropathy based on the CEACAM21 level, and then administering appropriate therapeutic agents according to the stratification results.

[0023] Beneficial technical effects of the present invention: 1. Diagnostic Efficacy and Precise Risk Stratification Capabilities of this Invention. This invention establishes for the first time the clinical value of serum carcinoembryonic antigen-associated cell adhesion molecule 21 (CEACAM21) as a novel biomarker for membranous nephropathy (MN). Receiver operating characteristic (ROC) curve analysis based on a prospective cohort showed that CEACAM21 exhibited extremely high accuracy in distinguishing between "MN patients and healthy controls" (AUC reaching 0.8410), confirming its high sensitivity as an auxiliary diagnostic indicator for MN. More importantly, as a single molecular marker, CEACAM21 can effectively differentiate between "high-risk progressive" and "low-risk non-progressive" MN patients at baseline levels (AUC reaching 0.8274). Compared to traditional clinical indicators, as a cell adhesion molecule, elevated serum levels of CEACAM21 may directly reflect the early stress-induced shedding or inflammatory adhesion state of glomerular podocytes or endothelial cells under immune complex attack. This molecular diagnostic tool based on pathophysiological mechanisms is significantly superior to traditional non-specific indicators in both sensitivity and specificity, providing a highly precise risk assessment method for clinical practice.

[0024] 2. This invention overcomes the bottleneck of the "observation period," enabling early intervention decisions based on molecular pathology. While the current KDIGO 2021 guidelines emphasize stratified treatment of MN (molecular inflammatory response), the lagging nature of indicators such as proteinuria and eGFR often forces clinicians to adopt a "wait-and-see" strategy lasting 3-6 months. This window of opportunity causes some high-risk patients in the latent progression phase to miss the optimal time to reverse podocyte damage. The core advantage of this invention lies in using "pre-treatment baseline serum" to overcome this timing dilemma. CEACAM21, as an upstream molecule reflecting the activity of the immune inflammatory microenvironment, can reveal immunological abnormalities in the body before the peak of proteinuria. By detecting baseline CEACAM21 levels, clinicians can shift treatment decisions from "passively waiting for clinical phenotype deterioration" to "active, proactive intervention based on molecular evidence." For low-risk patients: low CEACAM21 levels support conservative treatment (RAS blockers) and follow-up, effectively avoiding iatrogenic damage such as bone marrow suppression, infection, and metabolic disorders caused by alkylating agents or hormones. For high-risk patients: High levels of CEACAM21 indicate the initiation of an immune cytokine storm, supporting the early initiation of immunosuppressant or rituximab therapy before irreversible nephron sclerosis occurs, thereby maximizing the salvage of kidney function.

[0025] 3. This invention is highly correlated with disease burden, possessing both qualitative stratification and quantitative assessment value. This invention not only confirms the role of CEACAM21 in disease risk stratification but also reveals its potential as a quantitative indicator of disease activity. Statistical analysis shows a highly consistent correlation between serum CEACAM21 concentration and key clinical parameters reflecting the severity of kidney damage: significantly positively correlated with serum creatinine (r = 0.4023, P < 0.01) and 24-hour urinary protein quantification (r = 0.5180, P < 0.001), and significantly negatively correlated with eGFR (r = -0.2833, P < 0.05) and serum albumin (r = -0.3990, P < 0.01). This correlation suggests that CEACAM21 is not merely a switch-on diagnostic marker; its expression abundance can dynamically reflect the local immune complex deposition load and the degree of filtration barrier damage in the kidney. In clinical practice, this indicator is expected to serve as a "serological surrogate endpoint" to help doctors comprehensively assess the severity of the disease and make up for the shortcomings of a single proteinuria indicator that is easily affected by hemodynamics.

[0026] 4. Closed-Loop Evidence Chain of this Invention: Originating from Omics and Confirmed Clinically. The scientific validity of this invention is built upon a multi-dimensional closed-loop evidence chain, exhibiting extremely high reliability. First, through renal transcriptome mining of the GEO public database, it was discovered that the specific high expression of CEACAM21 is limited to renal tissue in membranous nephropathy, while no significant increase was observed in other glomerulonephritis such as IgA nephropathy and minimal change disease. Second, the study started with high-throughput Olink proteomics screening and successfully transitioned to the widely used clinical enzyme-linked immunosorbent assay (ELISA) for validation. In the independent validation cohort, CEACAM21 not only reproduced the ability to distinguish between MN and control, and between high-risk and low-risk individuals, but also demonstrated good cross-population stability. This complete logical chain from "discovery" to "validation" eliminates random errors and ensures the reproducibility of the results.

[0027] 5. This invention presents a highly promising "liquid biopsy" protocol for clinical translation. Compared to invasive kidney biopsy (which carries a risk of bleeding), this serum-based detection protocol offers the inherent advantages of being non-invasive, convenient, and reproducible. Convenient sampling: Only a small amount of peripheral blood is required, allowing testing at any time point, including initial outpatient visits, inpatient assessments, and long-term follow-ups, significantly improving patient compliance. Versatile technology: This invention has successfully established a standard ELISA-based detection method. This means that there is no need to rely on expensive mass spectrometers or specialized gene sequencing platforms; primary care hospital laboratories can conduct the test using existing ELISA readers. This low-cost, high-throughput technology has broad prospects for widespread application and significant socio-economic benefits. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 Differential protein volcano plots between each pair of the Healthy Control (HC) group, the Low-risk MN group, and the High-risk MN group; Figure 2 , three Venn diagram and protein trend plot of differentially expressed proteins between groups; Figure 3 Clustering heatmap results of 41 key differentially expressed proteins; Figure 4 Protein-protein interaction network (PPI) diagrams of key proteins and results of GO and KEGG enrichment analyses; Figure 5 ROC curves for differentiating between membranous nephropathy (MN) and healthy controls (HC); Figure 6 1. Differentiate between the hazard stratification ROC curves of the low-risk MN group and the high-risk MN group; Figure 7 Lasso regularization screening for key proteins associated with MN hazard stratification; Figure 8 ROC curves for the diagnosis and risk stratification of CEACAM21 in membranous nephropathy; Figure 9 Correlation analysis between CEACAM21 and clinical indicators (24-hour urinary protein quantification, eGFR, albumin, serum creatinine); Figure 10 The expression of CEACAM21 in the renal transcriptome of different types of glomerular diseases in the GEO database; Figure 11 The diagnosis and risk stratification of membranous nephropathy using CEACAM21 in an independent validation cohort. Invention Details This invention discloses the application of CEACAM21 in the diagnosis of membranous nephropathy. Those skilled in the art can refer to this document to implement its application. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can obviously make modifications or appropriate alterations and combinations to the preparation methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] Reference will now be made to detailed embodiments of the invention, one or more of which are described below. Each example is provided for explanation and not for limitation. It will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments. Therefore, the invention is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the invention are disclosed in or will be apparent from the following detailed description. It should be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the invention.

[0031] Diagnostic uses Based on Olink proteomics technology and renal transcriptomics analysis, this invention is the first to discover that carcinoembryonic antigen-associated cell adhesion molecule 21 can distinguish between high-risk and low-risk patients with membranous nephropathy earlier and more specifically. This breakthrough overcomes the limitations of the current KDIGO guidelines, which rely on lagging indicators such as proteinuria and renal function, and provides molecular evidence that precedes clinical progress for the precise initiation of hormone and immunosuppressive therapy.

[0032] Therefore, in various aspects of this disclosure, the use of CEACAM21 as a biomarker for the diagnosis of membranous nephropathy (MN) is provided, as well as the use of a detection agent for obtaining the level of CEACAM21 in a sample in the diagnosis of membranous nephropathy or in the preparation of products for the diagnosis of membranous nephropathy.

[0033] The term "membranous nephropathy" used in this article is abbreviated as MN, also known as membranous glomerulonephritis. It is one of the more common glomerular diseases in the adult population, characterized by the deposition of immune complexes under the extraepithelial cells of the glomerular basement membrane and diffuse thickening of the capillary walls. The terms "carcinoembryonic antigen-associated cell adhesion molecule 21" or "CEACAM21" used in this article are interchangeable, as they belong to the CEA cell adhesion molecule family.

[0034] As used herein, "diagnosis" refers to the process of identifying a medical condition or disease (such as MN) through the results of its diagnostic procedures, including detecting CEACAM21 levels in biological samples (such as serum) obtained from an individual. Furthermore, the term "diagnosis" as used herein can include screening for MN, early diagnosis, auxiliary diagnosis, definitive diagnosis (determining the presence of a disease), assessment of disease severity (disease stratification), assessment of disease activity, and monitoring of treatment. Without limitation, in some specific embodiments of the present invention, it has been sufficiently demonstrated that CEACAM21 levels can be used to determine the presence or absence of MN in a subject, as well as for severity stratification, and thus for screening, early diagnosis, auxiliary diagnosis, definitive diagnosis, or disease stratification of MN.

[0035] As used herein, the terms “sample,” “sample,” “test sample,” “subject sample,” and “subject sample,” etc., encompass a wide range of sample types obtained from patients, individuals, or subjects and that can be used for diagnostic or monitoring assays. Patient samples can be obtained from healthy subjects, patients with illnesses (including high-risk and low-risk types), or patients with MN-related symptoms. Furthermore, samples obtained from patients can be aliquoted, and only a portion may be used for diagnosis. Additionally, samples or portions thereof may be stored under conditions that allow for subsequent analysis. This definition specifically includes a variety of liquid samples of biological origin (including, but not limited to, serum, plasma, whole blood, tissues, cells, body fluids, urine, semen, saliva, pleural effusion, ascites, cerebrospinal fluid, feces, and synovial fluid). In one specific embodiment, the sample includes a blood sample. In another embodiment, a serum sample is used. This definition also includes samples that have been manipulated in any way after acquisition, such as by centrifugation, filtration, precipitation, dialysis, chromatography, reagent treatment, washing, or enrichment of certain cell populations. These terms also include clinical samples and include cells in cultures, cell supernatants, tissue samples, organs, etc. Samples may also include fresh frozen and / or formalin-fixed, paraffin-embedded tissue blocks, such as blocks prepared from clinical or pathological biopsies, for pathological analysis or research by immunohistochemistry.

[0036] The terms “individual,” “object,” “subject,” and “patient” are used interchangeably in this document and refer to any mammalian object requiring diagnosis, treatment, or therapy, particularly humans.

[0037] As used herein, the term "ROC" or "ROC curve" can refer to a receptor operating characteristic curve. An ROC curve can be a graphical representation of the performance of a binary classifier system. For any given method, an ROC curve can be generated by plotting sensitivity against specificity at various threshold settings. Furthermore, provided at least one of three parameters (e.g., sensitivity, specificity, and threshold setting) is provided, an ROC curve can determine the value or expected value of any unknown parameter. Unknown parameters can be determined using a curve fitted to an ROC curve.

[0038] As used herein, the term “AUC” or “ROC-AUC” generally refers to the area under the receptor operating characteristic curve. This metric takes into account the sensitivity and specificity of a method and provides a measure of its diagnostic utility. Typically, ROC-AUC ranges from 0.5 to 1.0, where values ​​closer to 0.5 indicate limited diagnostic utility (e.g., low sensitivity and / or specificity), and values ​​closer to 1.0 indicate greater diagnostic utility (e.g., high sensitivity and / or specificity). See, for example, Pepe et al., “Limitations of the Odds Ratio in Gauging the Performance of a Diagnostic, Prognostic, or Screening Marker”, Am. J. Epidemiol 2004, 159(9):882-890, which is incorporated herein by reference in its entirety. Other methods for characterizing diagnostic utility using likelihood functions, odds ratios, information theory, predicted values, calibration (including goodness of fit), and reclassification measures are outlined in Cook, “Use and Misuse of the Receiver Operating Characteristic Curve in Risk Prediction”, Circulation 2007, 115:928-935, which is incorporated herein by reference in its entirety.

[0039] Detection reagents for obtaining CEACAM21 levels in samples can be understood to include various types of detection reagents that directly or indirectly obtain CEACAM21 levels in samples.

[0040] According to some embodiments of the present invention, biomarker level indicators can be obtained at the nucleic acid level, protein level, or any other method. The detection method is not limited, but any method that can be used to directly or indirectly evaluate the CEACAM21 nucleic acid (especially transcriptomic nucleic acid) or protein level is suitable for the present invention. It is understood that there are various methods for nucleic acid level detection, including but not limited to sequencing technology, nucleic acid amplification technology, nucleic acid hybridization technology, electrophoresis technology, biomolecular mass spectrometry, or chromatography technology; all of these technologies can be used in the present invention. In some specific embodiments of the present invention, including but not limited to any of the following specific methods: gene sequencing, polymerase chain reaction, isothermal amplification reaction, gene chip method, probe hybridization method, gel electrophoresis, RNA blotting, nucleic acid mass spectrometry, or liquid chromatography.

[0041] It is understood that there are various protein detection methods in the art, including but not limited to sequencing technology, immunoassay technology, electrophoresis technology, biomolecular mass spectrometry technology, or chromatography technology, all of which can be used in this invention; in some specific embodiments of this invention, including but not limited to any of the following specific methods: amino acid sequencing, enzyme-linked immunosorbent assay (ELISA), chemiluminescence immunoassay, immunochromatography, radioimmunoassay, immunohistochemistry, immunoblotting, flow cytometry, gel electrophoresis, proteometry, or liquid chromatography.

[0042] For example, in one specific embodiment of the present invention, the method for quantitatively detecting CEACAM21 at the protein level includes ELISA detection based on specific antibodies. Here, specific antibodies refer to antibodies capable of specifically recognizing the CEACAM21-encoded protein, specifically including but not limited to monoclonal antibodies (e.g., full-length or intact monoclonal antibodies), polyclonal antibodies, multivalent antibodies, multispecific antibodies (e.g., bispecific antibodies with the intended biological activity), nanobodies, or at least one of certain antibody fragments. It is understood that the antibody can be human, humanized, and / or affinity-matured antibodies.

[0043] According to the experimental data of the present invention, CEACAM21 can be used as an independent indicator for the diagnosis of membranous nephropathy, and effective diagnosis of membranous nephropathy can be achieved solely based on CEACAM21.

[0044] It is understandable that, to further enhance the diagnostic efficacy for membranous nephropathy, the biomarkers detected by the reagent can also be other biological materials known to those skilled in the art, such as nucleic acid fragments, proteins, and metabolites, that can be used as biomarkers. This allows for the combined use of multiple biomarkers, working synergistically to achieve better diagnostic results for patients with membranous nephropathy, thus achieving a more effective diagnostic assessment. Therefore, CEACAM21, in addition to serving as an independent indicator for the diagnosis of membranous nephropathy, can also be used in conjunction with other existing known diagnostic markers to improve diagnostic efficacy.

[0045] In some embodiments of the present invention, the test sample may be selected from tissues, cells, body fluids, serum, plasma, whole blood (peripheral blood), urine, semen, saliva, pleural fluid, ascites, cerebrospinal fluid, feces, and synovial fluid; in a preferred embodiment, the test sample is selected from any one of serum, plasma, or whole blood.

[0046] Diagnostic methods Based on the above diagnostic applications, the core of the diagnostic method of the present invention includes the step of detecting or determining CEACAM21 in a subject sample; In some specific embodiments, the method includes the following steps: To detect or determine the level of CEACAM21 in the test sample; The levels of CEACAM21 were compared with those of the control sample; wherein a significant difference in the levels of CEACAM21 between the test sample and the control sample was an indication that the subject had membranous nephropathy. or, The sample level is compared with a predetermined absolute threshold; wherein, a level above the absolute threshold is an indication that the subject has membranous nephropathy.

[0047] In some embodiments, “CEACAM21 level” or “CEACAM21 level” in the text includes, but is not limited to, the abundance or concentration of CEACAM21 nucleic acid or protein. For example, in some specific embodiments, it refers to the expression abundance or concentration of the corresponding protein.

[0048] It is understood that the control sample can be selected according to actual needs. For example, in the diagnosis of the presence or absence of a disease, the control sample can be a sample from a normal or healthy population; while in the stratification of disease severity, the control sample can be a low-risk MN control sample. The specific control sample of this invention is not limited; based on the core of this invention, those skilled in the art can make reasonable selections according to actual application scenarios.

[0049] In some specific implementations, a setpoint for the CEACAM21 level can be provided. This setpoint can be determined based on the expression level of CEACAM21 in normal samples from healthy individuals and / or patients with non-membranous nephropathy. For example, the average expression level of CEACAM21 in a suitable number of normal samples can be selected, or a reasonable multiple of this average can be set, such as 0.9, 0.7, or 0.6 times. When the CEACAM21 expression level of a subject is higher than this setpoint, it is judged as membranous nephropathy. It is understood that the setpoint determined based on the average or a multiple of the average needs to have good classification significance. Common statistical tests can be used to test known samples based on the classification of this setpoint. When the results are statistically significant, it indicates that the setpoint can be used as a judgment criterion. The CEACAM21 level refers to the value of this biomarker for the subject, obtained through direct measurement or further indirect derivation from direct measurement. It is usually at least partially derived from the abundance or concentration of the biomarker in the subject's sample. The indirect derivation includes obtaining the value by applying a function to the measured value of this biomarker. Direct measurement values ​​include, but are not limited to, values ​​of biomarkers determined by at least one of the following methods: sequencing, hybridization, mass spectrometry, immunoassay, immunofluorescence, flow cytometry, etc.

[0050] Therapeutic uses After a subject is diagnosed with membranous nephropathy based on CEACAM21, whether it is determined whether the subject is diagnosed with membranous nephropathy or the severity of the membranous nephropathy is differentiated, those skilled in the art can provide precise drug administration based on this information. In some implementations, given that CEACAM21 can reveal immunological abnormalities in the body before the peak of proteinuria, by detecting CEACAM21 levels, physicians can shift treatment decisions from "passively waiting for clinical phenotype to worsen" to "active, proactive intervention based on molecular evidence": For low-risk patients, low levels of CEACAM21 support conservative treatment (such as RAS blockers), thus effectively avoiding iatrogenic damage such as bone marrow suppression, infection, and metabolic disorders caused by alkylating agents or hormones; For high-risk patients: high levels of CEACAM21 indicate that an immune cytokine storm has been initiated, supporting the early initiation of immunosuppressants or rituximab treatment before irreversible nephron sclerosis occurs, thereby maximizing the salvage of renal function.

[0051] Diagnostic products As can be seen from the core diagnostic application of this invention, the procedure for detecting CEACAM21 levels can be configured into a corresponding product form for the diagnosis or prediction of membranous nephropathy. This product includes reagents or kits for detecting the CEACAM21 biomarker.

[0052] In some embodiments of the invention, diagnostic kits for detecting or analyzing CEACAM21 levels to predict MN disease are also disclosed herein. Such kits include at least a set of reagents for detecting CEACAM21 levels and may also include instructions for predicting MN disease based on the detected levels.

[0053] The kit may include a set of reagents for generating a dataset through at least one assay. This set of reagents is capable of detecting and quantifying CEACAM21 levels. Of course, for combined assays, this set of reagents may also further detect the levels of one or more other biomarkers. In some respects, the reagents are for detection at the nucleic acid or protein level.

[0054] When the detection reagent is used for nucleic acid detection, it is understood that there are various nucleic acid detection methods in the art, including but not limited to sequencing technology, nucleic acid amplification technology, nucleic acid hybridization technology, electrophoresis technology, biomolecular mass spectrometry technology, or chromatography technology, all of which can be used in this invention. In some specific embodiments of this invention, including but not limited to any of the following specific methods: gene sequencing, polymerase chain reaction, isothermal amplification reaction, gene chip method, probe hybridization method, gel electrophoresis, RNA blotting, nucleic acid mass spectrometry, or liquid chromatography.

[0055] When the detection reagent is used for protein detection, it is understood that there are various protein detection methods in the art, including but not limited to sequencing technology, immunoassay technology, electrophoresis technology, biomolecular mass spectrometry technology, or chromatography technology, all of which can be used in this invention. In some specific embodiments of this invention, it includes, but is not limited to, any of the following specific methods: amino acid sequencing, enzyme-linked immunosorbent assay (ELISA), radioimmunoassay, immunohistochemistry, Western blotting, flow cytometry, gel electrophoresis, proteometry, or liquid chromatography. In some specific embodiments, the reagent is a specific antibody reagent, wherein a specific antibody refers to an antibody capable of specifically recognizing the CEACAM21-encoded protein, specifically including but not limited to monoclonal antibodies (e.g., full-length or complete monoclonal antibodies), polyclonal antibodies, multivalent antibodies, multispecific antibodies (e.g., bispecific antibodies with the expected biological activity), or at least one of certain antibody fragments. It is understood that the antibody can be human, humanized, and / or affinity-matured antibodies. Based on the antibody reagent, ELISA kits, WB kits, etc., can be prepared.

[0056] In some embodiments, such a kit may include a carrier, packaging, or container, said packaging or container being compartmentalized to receive one or more containers, such as vials, tubes, etc., each containing one of the independent elements to be used in the method. The kit of the present invention may include the containers described above, as well as one or more other containers containing substances required from a commercial end-user perspective, said substances including buffers, diluents, filters, and packaging instructions with usage instructions.

[0057] In some embodiments, the kit further includes sample processing reagents, which may include at least one of sample lysis reagents, sample purification reagents, and sample extraction reagents.

[0058] In some embodiments, the product further includes at least one of standards, calibrators, control standards, and buffer solutions. The control standard serves as a control to verify the validity of the experiment and as a reference for interpreting the results. The buffer solution can be any solution known in the art capable of providing appropriate buffering conditions during the detection process.

[0059] The kit may include instructions for use of a set of reagents. For example, the kit may include instructions for performing at least one assay, such as immunoassay, protein binding assay, antibody-based assay, antigen-binding protein-based assay, protein array, enzyme-linked immunosorbent assay (ELISA), flow cytometry, protein array, Western blotting, protein blotting, turbidimetry, chromatography, mass spectrometry, enzyme activity assay, and immunoassay, wherein the immunoassay is selected from RIA, immunofluorescence, immunochemiluminescence, immunoelectrochemiluminescence, immunoelectrophoresis, competitive immunoassay, and immunoprecipitation.

[0060] In addition to the components described above, the kit may further include instructions for implementing the subject method. These instructions may exist in various forms within the subject kit, including one or more forms. One possible form of these instructions is as printed information on a suitable medium or substrate, such as one or more sheets of paper with the information printed thereon, which are included in the kit packaging as inserts, etc.

[0061] Other aspects It is understandable that, given the certainty that CEACAM21 can serve as a diagnostic biomarker for membranous nephropathy, those skilled in the art can use this biomarker as a reference standard to evaluate or screen other potential diagnostic biomarkers for membranous nephropathy. In practice, potential biomarkers are usually evaluated for correlation with CEACAM21. A positive correlation conclusion helps to illustrate the diagnostic value of potential biomarkers.

[0062] The present invention may also relate to a method for detecting biomarkers in subjects with or suspected of having membranous nephropathy in vivo or in vitro, the method comprising determining or detecting the level of CEACAM21 in a biological sample from the subject, the method may include non-disease diagnostic uses.

[0063] Additionally, the present invention may also relate to a method for screening therapeutic agents for membranous nephropathy in vivo or in vitro, the method comprising the step of evaluating CEACAM21 levels in samples treated with the therapeutic agent, and evaluating the therapeutic efficacy of the therapeutic agent based on the CEACAM21 levels. For example, a decrease in CEACAM21 levels helps to indicate the therapeutic efficacy of the therapeutic agent.

[0064] The embodiments of the present invention will be described in detail below with reference to examples.

[0065] Example 1. Study cohort construction and clinical risk stratification based on KDIGO guidelines This invention employs a single-center retrospective study design, constructing a discovery cohort (Cohort 1) for biomarker screening. Participants were recruited from Shanxi Provincial People's Hospital between January 2022 and June 2024. Cohort 1 included 80 participants, divided into a healthy control group and a membranous nephropathy (MN) group, with the following composition: Healthy control group (HC): 30 healthy individuals selected from the same period's physical examination center; fasting serum samples were collected as a physiological baseline control. Membranous nephropathy group (MN): 50 patients selected from the nephrology ward. All patients were pathologically diagnosed by renal biopsy, and serum sample collection was completed before any immunological intervention.

[0066] The inclusion and exclusion criteria for the MN group strictly followed the following principles: Inclusion criteria: (1) Pathologically confirmed membranous nephropathy as defined by the KDIGO guidelines; (2) Primary membranous nephropathy (pMN); (3) Complete clinical medical records and laboratory test data (including complete blood count, liver and kidney function, electrolyte profile and anti-PLA2R antibody titer, etc.); (4) No history of immunosuppressant therapy (treatment-naïve patients); (5) Age between 18 and 65 years.

[0067] Exclusion criteria: (1) Secondary MN or associated autoimmune diseases (such as systemic lupus erythematosus, hepatitis B virus-associated nephritis, etc.); (2) Patients with malignant tumors.

[0068] Clinical Risk Stratification Strategy: To accurately assess the value of biomarkers in guiding treatment decisions, this invention stratified 50 patients with myasthenia gravis (MN) according to the KDIGO clinical practice guidelines. Based on whether they met the clinical indications for using glucocorticoids, immunosuppressants, or rituximab, patients were divided into two categories: High-risk MN (n=36): Patients whose condition met the criteria for immediate initiation of immunosuppressive therapy according to the KDIGO guidelines. Low-risk MN (n=14): Patients whose condition did not yet meet the criteria for initiating immunotherapy, and whose clinical treatment primarily consisted of symptomatic supportive care and close follow-up. This invention has been approved by the Ethics Committee of the Affiliated People's Hospital of Shanxi Medical University, and all participants have signed informed consent forms.

[0069] 2. Olink-based serum proteomics detection This invention utilizes the Olink® Explore 384-plex Inflammation Panel (OlinkProteomics AB, Uppsala, Sweden) to perform high-throughput targeted proteomics analysis on baseline serum samples from subjects. This panel is specifically designed to detect low-abundance biomarkers and covers 384 proteins highly associated with inflammatory cascades, immune regulation, and cytokine signaling pathways.

[0070] The experimental procedure specifically includes the following steps: 1) Sample Pretreatment and Immuno-reaction: Thaw the baseline serum sample collected from the subject before treatment on ice and centrifuge to remove the precipitate. Mix a small amount of serum (usually 1 µL) with an incubation mix containing 384 pairs of oligonucleotide-labeled antibodies in a 96-well plate. After sealing, incubate overnight (16-24 hours) at 4°C to allow the antibody probes to fully bind to the target protein. 2) Extension and Pre-amplification: After incubation, add extension mix (containing DNA polymerase) to the reaction system. Perform a PEA reaction in a thermal cycler: heating causes adjacent oligonucleotide probes to hybridize and extend, generating a double-stranded DNA template suitable for PCR amplification. Immediately afterwards, perform PCR pre-amplification to exponentially amplify specific DNA barcode signals, ensuring that low-abundance protein signals can be detected. 3) Indexing & Library Preparation: A second round of PCR is used to add a specific sample index sequence and adapter sequences compatible with the Illumina sequencing platform to each sample. This step allows samples from different patients to be multiplexed in the same sequencing lane. 4) Library Purification & Quality Control: PCR products from all samples are pooled, and the mixed library is purified using magnetic beads to remove unreacted primers, free nucleotides, and nonspecific short fragments. The fragment size distribution and concentration of the final library are accurately determined using an Agilent 2100 Bioanalyzer or TapeStation to ensure the library quality meets the requirements for sequencing. 5) High-Throughput Sequencing (NGS Sequencing): The quality-controlled library is loaded onto the Illumina NovaSeq 6000 sequencing platform for paired-end sequencing. The sequencing depth is set to meet the requirement of the average number of reads per protein per sample to ensure the statistical power of the data. 6) Data generation and standardization: After adapter removal and alignment, the raw sequencing data is used to count the number of reads for each specific barcode.The data were quality controlled and normalized using Olink's proprietary algorithm (Olink NPX Manager) combined with internal controls, ultimately outputting NPX (Normalized Protein eXpression) values. NPX is a relative quantitative unit based on the log2 scale; each increase of 1 in the NPX value represents a doubling of protein concentration.

[0071] 3. Differential protein screening and bioinformatics analysis Based on the obtained NPX data matrix, this invention mines differentially expressed proteins (DEPs) according to the following logic (see attached diagram). Figure 1-4 ): (1) Analysis of differences between groups: HC group vs. MN group were plotted separately (see appendix). Figure 1 A) HC group vs. MN low-risk group (see appendix) Figure 1 B), and MN low-risk group vs MN high-risk group (see appendix) Figure 1 C) Volcano map visually illustrates the differential distribution.

[0072] (2) Intersection to identify key proteins: The Venn diagram was used to perform an intersection analysis on the DEPs generated from the above three sets of comparisons (see Appendix). Figure 2 The results showed that 46 proteins exhibited significant differences among the three groups (P < 0.05).

[0073] (3) Trend Analysis and Functional Annotation: Further analysis revealed that the expression levels of 41 proteins gradually increased with disease progression (health → low risk → high risk), suggesting a close relationship with the occurrence, development, and severity of MN. This invention defines these 41 proteins as "key candidate proteins" and generates a clustering heatmap (see Appendix). Figure 3 Subsequent GO functional annotation and KEGG pathway enrichment analysis (see Appendix) Figure 4 AB) and PPI protein interaction network analysis (see appendix) Figure 4 (C), revealing the central role of these proteins in the immune inflammatory cascade.

[0074] 4. Multidimensional cascade screening of core biomarkers To extract core biomarkers with both diagnostic efficacy and stratification guidance value from 41 candidate proteins, this invention designs a four-step cascaded screening strategy to establish the optimal combination of biomarkers. The screening criteria are set as follows: (1) Initial screening for diagnostic efficacy: The area under the ROC curve (AUC) for distinguishing between healthy individuals (HC) and membranous nephropathy (MN) needs to be >0.8 (see Appendix 1 and Figure 5 ).

[0075] (2) Risk stratification capability: The AUC of the ROC curve that distinguishes between high-risk MN and low-risk MN needs to be > 0.8 (see Appendix 1 and ...). Figure 6 ).

[0076] Table 1. Diagnosis and Risk Stratification of Membranous Nephropathy (MN) - ROC Curve AUC Values (3) Clinical correlation verification: The protein expression level should show a significant correlation with traditional clinical indicators such as 24-hour urinary protein (24h-UTP), estimated glomerular filtration rate (eGFR), serum albumin (Alb) and serum creatinine (Scr) (see Appendix Table 2).

[0077] Table 2. Correlation analysis of 41 key differentially expressed proteins with clinical indicators. (4) Model dimensionality reduction and optimization: The Lasso regression regularization algorithm is introduced to remove redundant features and lock in the most representative variables (see Appendix). Figure 7 ).

[0078] Based on the above criteria, this invention ultimately identified six core proteins from a pool of 41 candidates: IL15RA, CSF1, VEGFD, CEACAM21, IFNGR1, and LTBR. In cohort 1 data, these histones not only accurately diagnosed MN but also effectively differentiated disease risk levels, demonstrating the potential to guide immunosuppressive therapy.

[0079] Example 2: Screening for the biomarker CEACAM21 as a risk stratification biomarker for membranous nephropathy In the initial screening of inflammatory proteomics based on the Olink 384-plex platform of this invention, CEACAM21 was identified as the target molecule due to its dual value in the two core dimensions of "basic disease diagnosis" and "treatment decision support". Specifically, this biomarker exhibits the following technical effects: First, significant efficacy in basic diagnosis. At baseline levels before treatment, CEACAM21 can effectively distinguish between patients with primary membranous nephropathy (MN) and healthy individuals, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.8410 (see Appendix). Figure 8 This confirms its specific identification ability as a diagnostic marker for MN. Secondly, it possesses early risk stratification value. Addressing the decision-making difficulty regarding "whether to initiate immunosuppressive therapy" in the clinical treatment of MN, the CEACAM21 single indicator can distinguish between high-risk (requiring immunotherapy) and low-risk (requiring only supportive care) patients at baseline, with an AUC value of 0.8274 (see appendix). Figure 8This feature allows clinicians to predict the course of a disease in advance without relying on the traditional 3-6 month observation period, effectively solving the technical problem of delayed early treatment decisions.

[0080] Further Spearman correlation analysis (see appendix) Figure 9 The results showed a clear linear relationship between serum CEACAM21 abundance and disease activity indicators: it was significantly positively correlated with serum creatinine (Scr) and 24-hour urinary protein quantification, but significantly negatively correlated with estimated glomerular filtration rate (eGFR). These data indicate that CEACAM21 is not only a qualitative classification marker, but also a quantitative indicator that dynamically reflects the degree of renal function impairment and proteinuria load. Given the lack of precedent in the current technology for using serum CEACAM21 to determine the necessity of early immunotherapy for membranous nephropathy, this invention identified it as the core validation target and designed a dual validation scheme of "histological transcriptomics" and "independent serological cohort".

[0081] Example 3: Further validation of CEACAM21 as a biomarker for risk stratification in membranous nephropathy This example further validates the diagnostic performance of the CEACAM21 biomarker through two aspects.

[0082] 1. Validation of kidney tissue transcriptomics based on multicenter datasets To verify the expression specificity of CEACAM21 at the tissue level, this embodiment integrates four independent tissue sample transcriptome datasets (GSE175759, GSE197307, GSE200828 and GSE261305) from the GEO database for systematic comparative analysis.

[0083] The results of the differential expression analysis showed (see appendix) Figure 10 Compared to other types of glomerular diseases such as IgA nephropathy, focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), and lupus nephritis (LN), the CEACAM21 gene exhibits a significantly high expression pattern only in the kidney tissue of primary membranous nephropathy. This result rules out the possibility of CEACAM21 as a non-specific pan-nephritis inflammatory marker and confirms at the molecular pathological level that its upregulation is closely related to the specific pathogenesis of membranous nephropathy (MN), demonstrating disease type specificity.

[0084] 2. Reproducibility and validation of the diagnostic and stratification efficacy of CEACAM21 in a new independent clinical cohort. To evaluate the robustness of CEACAM21 across different detection platforms and populations, this invention constructed a new independent validation cohort (cohort 2) and used enzyme-linked immunosorbent assay (ELISA) for serological testing.

[0085] 1) Clinical Data and Grouping: The study subjects were 456 participants who visited the Department of Nephrology at Shanxi Provincial People's Hospital between January 2022 and December 2025. These included: (1) 271 patients with primary MN diagnosed by renal biopsy; (2) 147 non-MN chronic glomerulonephritis control group (including IgA nephropathy, FSGS, MCD, etc.); and (3) 38 healthy controls. Based on the KDIGO guidelines, MN patients were further divided into a high-risk group (n=228, requiring immunosuppressive therapy to block progression) and a low-risk group (n=43, requiring only symptomatic supportive treatment).

[0086] 2. Detection Methods and Statistical Analysis: Serum samples were collected from all subjects. The concentration of CEACAM21 protein was quantitatively determined using an enzyme-linked immunosorbent assay (ELISA) kit (Jiangsu Enzyme Immunosorbent Assay Co., Ltd., catalog number: MM-65707H1 96T). Combined with clinical and biochemical indicators, ROC curves were constructed using Graphpad Prism software to calculate AUC values, sensitivity, and specificity, and to determine the optimal cut-off value to evaluate its clinical efficacy.

[0087] 3. The analysis results are attached. Figure 11 As shown, specifically: Intergroup differences: Serum CEACAM21 levels in the MN group were significantly higher than those in the healthy control group (P < 0.05); within the MN group, the levels in high-risk patients were significantly higher than those in low-risk patients (P < 0.001), and both were significantly higher than those in the non-MN nephropathy control group (P < 0.001). (2) Diagnostic efficacy: The AUC was 0.8639 (P < 0.001) when distinguishing between MN patients and healthy controls. When the diagnostic cutoff value was set at 103.1 pg / mL, the sensitivity was 80.15% and the specificity was 81.58%.

[0088] (3) Risk stratification efficacy: The AUC was 0.8367 (P < 0.001) when differentiating between high-risk and low-risk MN patients. When the stratification cutoff value was set at 98.57 pg / mL, the sensitivity was 77.29% and the specificity was 81.40%. These data indicate that the high specificity at this threshold makes it suitable for the auxiliary screening and confirmation of high-risk patients in clinical practice.

[0089] In conclusion, independent cohort validation has confirmed the reliability of serum CEACAM21 as a novel biomarker, and it has clear prospects for clinical translational application in the auxiliary diagnosis of MN and the guidance of immunotherapy decision-making.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The application of a detection reagent for obtaining CEACAM21 levels in a sample in the preparation of a product for diagnosing kidney disease, or the application of CEACAM21 as a biomarker in the preparation of a product for diagnosing kidney disease; preferably, the kidney disease is membranous nephropathy.

2. A product for diagnosing kidney disease, characterized in that, It includes a detection agent for obtaining the level of CEACAM21 in a sample; preferably, the kidney disease is membranous nephropathy.

3. The application according to claim 1 or the product according to claim 2, characterized in that, The diagnosis of nephropathy includes distinguishing between MN patients and healthy individuals, or between high-risk MN patients and low-risk MN patients.

4. The application according to claim 3 or the product according to claim 2, characterized in that, The levels mentioned include nucleic acid levels or protein levels.

5. According to claim 4, the characteristic is that, The nucleic acid level is obtained through sequencing technology, nucleic acid amplification technology, nucleic acid hybridization technology, electrophoresis technology, biomolecular mass spectrometry technology, or chromatography technology.

6. According to claim 4, the characteristic is that, The protein levels were obtained using sequencing, immunoassay, electrophoresis, mass spectrometry, or chromatography.

7. The method according to any of the preceding claims, characterized in that, The sample includes one or more of the following: tissue, cells, body fluid, serum, plasma, whole blood, urine, semen, saliva, pleural effusion, ascites, feces, or synovial fluid; preferably, the sample is serum, plasma, or whole blood.

8. A method for diagnosing membranous nephropathy in vivo or in vitro, characterized in that, This includes the step of obtaining CEACAM21 levels in subject samples; Preferably, the method includes the following steps: (i) Obtain the CEACAM21 level in the subject samples; (ii) Comparison of CEACAM21 levels with control samples; wherein a significant difference in CEACAM21 levels between the subject sample and the control sample is an indication that the subject has membranous nephropathy; or, (ii) Compare with a set absolute threshold; wherein, the subject sample level being higher than the absolute threshold is an indication that the subject has membranous nephropathy.

9. A method for detecting biomarkers in subjects with or suspected of having membranous nephropathy, either in vivo or in vitro, characterized in that, The method includes determining or detecting CEACAM21 levels in samples from subjects.

10. A treatment method for membranous nephropathy, characterized in that, The treatment method includes: assessing the CEACAM21 level of the subject and administering appropriate therapeutic agents based on the assessment results.

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