Application of BDNF in predicting the risk of postpartum depression

Abstract

The application relates to application of BDNF as a biomarker in prenatal prediction of postpartum depression morbidity risk. The mBDNF and proBDNF levels in cerebrospinal fluid and plasma can be used as independent markers for prediction of postpartum depression morbidity risk, and the plasma mBDNF or cerebrospinal fluid proBDNF level can be used for prediction of postpartum depression morbidity risk through prenatal detection, which is helpful for prediction, early identification and timely intervention of postpartum depression and reduction of harm.

Description

Technical Field

[0001] This invention belongs to the field of molecular diagnostic technology, specifically relating to the application of BDNF as a biomarker in prenatal prediction of the risk of postpartum depression. Background Technology

[0002] Postpartum depression (PD) often goes untreated due to its insidious onset and lack of awareness, thus harming the mother's physical and mental health, disrupting the mother-infant attachment, and having a detrimental effect on the offspring's cognition, emotions, and behavioral trajectories. In recent years, abnormal neuroplasticity has been considered a key central mechanism in the development of depression, and brain-derived neurotrophic factor (BDNF), as a key factor regulating neuroplasticity, plays an important role in the pathogenesis of PPD (Qin M, Chen Y, Wang X, et al. Dexmedetomidine induces IL-10 secretion by B lymphocytes in the peripheral blood of patients with hepatocellular carcinoma [J]. Immunobiology, 2024, 229(5): 152842;Park H, Poo MM. Neurotrophin regulation of neural circuit development and function [J]. Nature Reviews Neuroscience, 2012, 14(1): 7-23). In addition to promoting the growth, differentiation and migration of neurons, BDNF is crucial for the formation and stability of synapses, thus playing an important role in nervous system function, learning and memory, and emotion regulation (Arancio O, Chao MV. Neurotrophins, synaptic plasticity and dementia [J]. Current Opinion in Neurobiology, 2007, 17(3): 325-30; Lu B, Pang G, Hew NH, et al. New insights into the role of brain-derived neurotrophic factor in synaptic plasticity [J]. Molecular and Cellular Neuroscience, 2009, 42(2): 81-89).

[0003] Under physiological conditions, BDNF primarily participates in the regulation of depression through two molecules with different activities: proBDNF and mature BDNF. ProBDNF preferentially binds to the p75 neurotrophin receptor (p75NTR), promoting apoptosis and synaptic pruning; while mBDNF activates tropomyosin receptor kinase B (TrkB) and downstream cAMP response element-binding protein (CREB) signaling, promoting the growth and development of nerve cells. The dynamic balance between proBDNF and mBDNF controls the homeostasis of the signaling regulatory network. Disruption of this balance may be a pathogenesis of PPD (Castrén E, Rantamäki T. The role of BDNF and its receptors in depression and antidepressant drug action: Reactivation of developmental plasticity [J]. Developmental Neurobiology, 2010, 70(5): 289-297; Zhang J, Yao W, Hashimoto K. Brain-derived Neurotrophic Factor (BDNF)-TrkB Signaling in Inflammation-related Depression and Potential Therapeutic Targets [J]. Current Neuropharmacology, 2016, 14(7): 721-731; Singh S, Fereshetyan K, Shorter S, et al. Brain-derived neurotrophic factor (BDNF) inperinatal depression: Side show or pivotal factor [J]. Drug Discovery Today, 2023, 28(2): 1-7).

[0004] Most current clinical studies use conventional methods to detect BDNF in blood, which often cannot accurately distinguish between proBDNF and mBDNF, possibly contributing to discrepancies in research results. No studies have simultaneously compared the differences in predictive sensitivity of cerebrospinal fluid (CSF) and peripheral blood BDNF (including its proBDNF and mBDNF subtypes) for prenatal papillary dysplasia (PPD). Therefore, there is an urgent need for prenatal diagnostic biomarkers with strong predictive power and cost-effectiveness to facilitate early detection and timely intervention for PPD. Summary of the Invention

[0005] This study recruited women scheduled for elective cesarean section and quantified BDNF subtypes (proBDNF and mBDNF) in CSF and plasma, systematically evaluating the predictive value of these biomarkers for PPD incidence. This invention constructs a PPD risk stratification model based on multimodal biomarkers, ultimately enabling precise perinatal intervention.

[0006] A first aspect of this invention provides a biomarker, BDNF, that can be used prenatally to predict the risk of postpartum depression. Preferably, BDNF is mBDNF or proBDNF. Through the pioneering genotyping assays of this invention, mBDNF and proBDNF have been found to serve as independent predictors of the risk of postpartum depression.

[0007] In a preferred embodiment, the biomarker is mBDNF. The risk of postpartum depression can be predicted by detecting the level of mBDNF in the plasma of pregnant women before delivery, and a lower plasma mBDNF level indicates a higher risk of postpartum depression.

[0008] In another preferred embodiment, the biomarker is proBDNF. The risk of postpartum depression can be predicted by detecting the level of proBDNF in the cerebrospinal fluid of pregnant women before delivery. Lower cerebrospinal fluid proBDNF levels predict a higher risk of postpartum depression.

[0009] A second aspect of the invention provides a reagent for detecting the levels of the aforementioned biomarkers in a sample, the reagent being capable of predicting the risk of postpartum depression by detecting the levels of the biomarkers prenatally.

[0010] The sample is the subject's plasma or cerebrospinal fluid.

[0011] In a preferred embodiment, the sample is plasma, and the biomarker to be detected is mBDNF.

[0012] In another preferred embodiment, the sample is cerebrospinal fluid, and the biomarker to be detected is proBDNF.

[0013] The reagent can be used to determine the concentration of the biomarker by various conventional detection methods; preferably, the determination is performed at the protein level; more preferably, by enzyme-linked immunosorbent assay (ELISA); most preferably, by DuoSet ELISA.

[0014] A third aspect of the invention provides a kit for predicting the risk of postpartum depression, comprising reagents for testing the levels of the aforementioned biomarkers in prenatal samples.

[0015] The sample is the subject's plasma or cerebrospinal fluid.

[0016] In a preferred embodiment, the sample is plasma, and the reagent is used to detect mBDNF levels.

[0017] In another preferred embodiment, the sample is cerebrospinal fluid, and the reagent is used to detect proBDNF levels.

[0018] The kit can be a detection kit for determining the concentration of biomarkers in a sample using various conventional detection methods, and accordingly includes other necessary reagents required for the detection methods. Preferably, the kit is an enzyme-linked immunosorbent assay (ELISA) kit, and includes other necessary reagents for ELISA. Most preferably, the kit is a DuoSet ELISA kit.

[0019] The positive effects of this invention are as follows: For the first time, this invention simultaneously compared the expression levels of two BDNF subtypes (mBDNF and proBDNF) in cerebrospinal fluid and plasma with the occurrence of postpartum diarrhea (PPD), demonstrating that there is no correlation between BDNF levels in cerebrospinal fluid and plasma, and that both should be considered independent biomarkers. Through more refined research than previous studies, it was found that lower prenatal cerebrospinal fluid and plasma proBDNF levels, as well as plasma mBDNF levels, can serve as independent predictors of PPD. In particular, due to the significant advantage of plasma in terms of sampling convenience compared to cerebrospinal fluid, prenatal testing of plasma mBDNF levels is a very promising method for predicting the risk of PPD, which can help predict, identify early, and intervene in PPD in a timely manner, and is of great significance for specifically reducing the harm of PPD to mothers. Attached Figure Description

[0020] Figure 1A and Figure 1BThis indicates a comparison of BDNF (mBDNF, proBDNF) concentrations among groups. (nPPD vs PPD: CSF mBDNF: 83.05 vs 89.95 ng / mL, P = 0.01, MD[95% CI]: -6.90 [-12.02, -1.78]; Plasma mBDNF: 52.04 vs 62.98 ng / mL, P<0.001, MD[95% CI]: -10.09 [-16.52, -5.28]; CSF proBDNF: 1320.41 vs 1215.16 pg / mL, P=0.01, MD[95% CI]: -105.26 [-185.62, -24.89]; Plasma proBDNF: 1013.28 vs 980.39) pg / mL, P=0.45, MD[95% CI]: -32.89[-119.01, 53.23]).

[0021] Figure 2 ROC curve analysis of BDNF (mBDNF, proBDNF) levels in cerebrospinal fluid and plasma to predict PPD.

[0022] Figure 3A and Figure 3B The correlation between mBDNF and proBDNF concentrations in plasma and cerebrospinal fluid is shown: Figure 3A Correlation between plasma and CSF mBDNF levels (ng / mL); Figure 3B Correlation between proBDNF levels (pg / mL) in plasma and CSF. mBDNF: r=0.16, P=0.09, 95% CI: -0.02~0.32. proBDNF: r=0.16, P=0.08, 95% CI: -0.02~0.33. Neither correlation reached statistical significance. Detailed Implementation

[0023] The present invention will be further illustrated by the following examples, but the invention is not limited thereto. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0024] I. Research Methods

[0025] This protocol was approved by the Ethics Committee of the Affiliated Lianyungang Hospital of Xuzhou Medical University (Approval No.: KY-20240701001-02; Approval Date: July 30, 2024) and registered in the Protocol Registration and Outcomes System (PRS; NCT06947278; Registration Date: April 20, 2025). This study was conducted at the Affiliated Lianyungang Hospital of Xuzhou Medical University.

[0026] 1. Research participants

[0027] A prospective nested case-control study included 200 pregnant women who underwent elective cesarean section under combined spinal-epidural anesthesia at the Affiliated Lianyungang Hospital of Xuzhou Medical University (a tertiary-level Class A hospital) from May 1, 2025 to September 1, 2025.

[0028] Inclusion criteria: indications for cesarean section and no contraindications to spinal anesthesia; age between 20 and 35 years; gestational age between 37 and 42 weeks; American Society of Anesthesiologists (ASA) classification II-III; single pregnancy; voluntary participation in this study and signing of informed consent.

[0029] Exclusion criteria: Inability to correctly understand the questionnaire; clear history of mental illness, depression, cognitive impairment or other similar conditions; long-term use of sedatives, analgesics or psychiatric medications; recent use of glucocorticoids or immunosuppressants; allergy or contraindication to any of the medications used in this study; severe pregnancy complications such as preeclampsia and placental spectrum disorders; participation in other clinical studies within the past 3 months.

[0030] 2. Data Collection

[0031] The day before delivery, the anesthesiologist who conducted the preoperative visit explained the purpose of the study and the risks and benefits of collecting cerebrospinal fluid; subsequently, 200 women signed written informed consent. Baseline information was collected at that time: age, BMI, gestational age, education level, non-invasive mean arterial pressure, heart rate, blood oxygen saturation, Pittsburgh Sleep Quality Index (PSQI), State-Trait Anxiety Scale (STAI), Numerical Rating Scale (NRS), and Social Support Rating Scale (SSRS) scores. EPDS (Wang et al., 2009) and HAMD-21 (Hamilton, 1960) scores were obtained 7 days postpartum via a WeChat questionnaire link and telephone, and 42 days postpartum at the postpartum follow-up visit. If no response was received, reminders were sent via WeChat and telephone at 1 week and 2 weeks postpartum; continued lack of response was recorded as a follow-up loss. Women with EPDS or HAMD-21 scores ≥9 who denied suicidal ideation received psychological support until their scores normalized. Once the women and their families consented, any indication of suicidal ideation was transferred to inpatient treatment. The research data will be kept for 5 years after the research is completed.

[0032] 3. Sample collection and BDNF measurement

[0033] On the day of surgery, upon arrival at the operating room, the patient underwent standard monitoring of heart rate, non-invasive blood pressure, and pulse oximetry. After establishing peripheral intravenous access, the patient was placed in the left lateral decubitus position for combined spinal-epidural anesthesia. 0.5 mL of CSF was collected immediately before intrathecal administration of bupivacaine. Simultaneously, 3 mL of peripheral venous blood was collected in an EDTA tube and centrifuged at 3000 rpm for 10 min at room temperature (stored at 22°C for no more than 1 h, or at 4°C for no more than 2 h).

[0034] CSF and plasma samples were frozen at -80°C and analyzed within 6 months. Human proBDNF and mBDNF in CSF and plasma were quantified using a commercial DuoSet ELISA kit (R&D Systems, Minneapolis, MN, USA) according to the manufacturer's instructions. Samples were prepared in duplicate, and calibration curves were fitted using a four-parameter logistic model. Intra- and inter-assay coefficients of variation were maintained below 15%.

[0035] Quality checks were performed on the collection equipment and consumables; all personnel involved in sampling and processing received systematic training in aseptic techniques and sample handling. Each step was monitored in real time to ensure consistency. Throughout storage, sample integrity was verified by designated personnel; each sample was barcode-tagged and electronically tracked. All human specimens were destroyed under supervision after analysis.

[0036] 4. PPD diagnosis (EPDS and HAMD-21)

[0037] Each EPDS item has four options, corresponding to scores of 0, 1, 2, and 3. A total EPDS score below 9 generally indicates no risk of postpartum depression, but the mother's mood changes should still be monitored; a total score > 9 may indicate postpartum depression, and close observation or professional help is recommended (Wang et al., 2009). Although EPDS is widely used for postpartum depression screening, it cannot be used to diagnose PPD; it can only be used as a positive screening tool (Zhou et al., 2024). Therefore, in this study, we not only collected the mothers' EPDS scores but also arranged for specialists to conduct HAMD-21 assessments on the patients.

[0038] The HAMD-21 is a heterologous rating scale, a clinical interview questionnaire used to assess the physiological and psychological symptoms of depression in patients. It comprehensively covers depressive symptoms and quantifies the severity of depression. Previous studies have shown that in China, the scale has optimal specificity and sensitivity when a cutoff score of 9 is used (Hamilton, 1960). However, the HAMD-21 includes many somatic symptoms that may overlap with normal postpartum physiological changes. Therefore, this study combines the Edinburgh Postpartum Depression Scale (EPDS) with the HAMD-21 to achieve a multi-dimensional assessment encompassing "subjective + objective," "psychological + physiological," and "screening + diagnostic elements," thereby improving the accuracy of postpartum depression identification. Patients were assigned to the PPD group if their Edinburgh Postpartum Depression Scale (EPDS) score was ≥9 at 7 or 42 days postpartum and / or their total HAMD-21 score was ≥9; otherwise, they were assigned to the nPPD group.

[0039] 5. Data Analysis

[0040] Normality of quantitative data was assessed visually using histograms and P-plots, as well as the Shapiro-Wilker test. For skewed distributions, variable transformations were performed based on the distribution characteristics before final analysis. Binary logistic regression was used to assess the relationship between mBDNF, proBDNF, TrkB, p-CREB levels and PPD in cerebrospinal fluid and blood. The accuracy of BDNF in predicting PPD in cerebrospinal fluid and blood was assessed using receiver operating characteristic (ROC) curves, and the area under the curve (AUC) was calculated as a measure of test accuracy. Normally distributed quantitative data were described as mean ± standard deviation, and intergroup comparisons were performed using independent samples t-tests and Pearson correlation analysis; skewed data were described as median (interquartile range), and intergroup comparisons were performed using the Mann-Whitney U test and Spearman correlation analysis. BonfeRRoni correction or the Benjamini-Hochberg method was used for multiple comparisons to reduce false positives. Count data were expressed as frequency and percentage, and intergroup differences were compared using chi-square tests or Fisher's exact test. Statistical significance was defined as P < 0.05. Statistical analysis was performed using SPSS 25.0 software (IBM SPSS, Chicago, IL).

[0041] II. Research Results

[0042] Cerebrospinal fluid and plasma samples were successfully collected from 156 parturients; 44 participants were excluded for the following reasons: 6 did not meet the inclusion criteria, 5 were switched to general anesthesia, 16 sampling was unsuccessful, 2 had serious pregnancy complications, and 15 withdrew / lost follow-up during the perioperative period. Of the 156 participants, 35 (22.4%) met the established criteria for PPD within the first 42 days: 29 (18.6%) on day 7 and 20 (12.8%) on day 42. No participant reported suicidal ideation at any assessment point. Table 1 summarizes the baseline characteristics of the participants.

[0043] Table 1. Demographic and obstetric characteristics of the participants (n=156)

[0044]

[0045] Data are expressed as mean ± SD, median (interquartile range), or percentage (%). Abbreviations: BMI, Body Mass Index; MAP, Mean Arterial Pressure; HR, Heart Rate; NRS, Numerical Rating Scale; PSQI, Pittsburgh Sleep Quality Index; STAI-1, State Anxiety Scale; STAI-2, Trait Anxiety Scale; SSRS, Social Support Rating Scale.

[0046] 1. Main Results

[0047] In the complete cross-sectional sample (n=156), the CSF mBDNF concentration in mothers with PPD was significantly lower than that in the nPPD control group (83.05 ng / mL vs 89.95 ng / mL, P = 0.01, MD[95% CI]: -6.90[-12.02, -1.78]); the reduction in plasma was even more pronounced (52.04 vs 62.98 ng / mL, P<0.001, MD[95% CI]: -10.09[-16.52, -5.28]). Meanwhile, compared with the nPPD group, the CSF proBDNF level was significantly lower in the PPD group (1320.41 vs 1215.16 pg / mL, P = 0.01, MD [95% CI]: -105.26 [-185.62, -24.89]), while there was no significant difference in plasma proBDNF between the two groups (1013.28 vs 980.39 pg / mL, P = 0.45, MD [95% CI]: -32.89 [-119.01, 53.23]). Figure 1A and Figure 1B ).

[0048] Further time-point analysis was conducted (Table 2).

[0049] Table 2 Comparison of BDNF concentrations and adverse events between the two groups

[0050]

[0051] Data are expressed as mean ± SD or as a percentage (%). Abbreviations: BDNF, brain-derived neurotrophic factor; mBDNF, mature BDNF; proBDNF, pre-brain-derived neurotrophic factor. aFisher exact test.

[0052] Based on PPD symptoms on day 7 postpartum: CSF mBDNF (89.21 ng / mL vs 82.70 ng / mL, P=0.02, MD[95% CI]: -6.52 [-12.11, -0.93]), plasma mBDNF (62.50 ng / mL vs 53.01 ng / mL, P=0.003, MD[95% CI]: -9.50 [-15.80, -3.20]), and CSF proBDNF (1325.84 pg / mL vs 1201.84 pg / mL, P=0.01, MD[95% CI]: -124.01 [-210.89, -37.12]) levels differed significantly between the PPD and nPPD groups, while plasma proBDNF levels (1020.74 pg / mL vs 82.70 ng / mL vs 82.70 ng / mL, P=0.02, MD[95% CI]: -6.52 [-12.11, -0.93]) showed significantly different levels between the PPD and nPPD groups. There was no significant difference between the two groups (957.40 pg / mL, P=0.19, MD[95% CI]: -63.34 [-158.83, 32.15]).

[0053] Based on PPD symptoms on day 42 postpartum, there was no significant difference in mBDNF concentration between the two groups in CSF (89.09 ng / mL vs 83.08 ng / mL, P=0.09, MD[95% CI]: -6.01[-12.89, -0.87]) and plasma (60.40 ng / mL vs 54.16 ng / mL, P=0.10, MD[95% CI]: -6.24[-13.60, 1.12]). There was also no significant difference in proBDNF concentration in plasma (992.29 pg / mL vs 1011.42 pg / mL, P=0.74, MD[95% CI]: 19.13[-96.33, 134.60]), and the concentration of proBDNF in CSF (1304.40 pg / mL vs 1187.58 pg / mL) was significantly different. P=0.03, MD[95% CI]:-116.82[-222.99,-10.64]) was significantly reduced in the PPD group.

[0054] In summary, the reduction of CSF proBDN was strongly correlated with PPD symptoms at both postpartum day 7 and day 42, while plasma mBDNF levels were more strongly correlated with PPD symptoms at postpartum day 7.

[0055] 2. Sensitivity Analysis

[0056] ROC analysis ( Figure 2 The results showed that plasma mBDNF had the highest accuracy in differentiating PPD, with an area under the curve (AUC) of 0.73 (P=0.001, 95% CI 0.64-0.83). CSF proBDNF showed similar results (AUC: 0.70, P=0.003, 95% CI 0.60-0.81), while CSF mBDNF showed a moderate difference (AUC: 0.67, P=0.02, 95% CI 0.55-0.78). Therefore, plasma mBDNF has the best diagnostic value for PPD.

[0057] 3. Correlation analysis

[0058] A total of 156 paired plasma and CSF samples were analyzed. The mean concentration (mean ± SD) was:

[0059] mBDNF: 60.7±13.2 ng / mL in plasma and 87.7±12.9 ng / mL in CSF;

[0060] proBDNF: 1006.2±197.3 pg / mL in plasma and 1295.9±204.4 pg / mL in CSF.

[0061] Pearson correlation analysis showed a weak positive correlation between plasma and CSF levels of mBDNF (r = 0.16, P = 0.09, 95% CI: -0.02–0.32) and proBDNF (r = 0.16, P = 0.08, 95% CI: -0.02–0.33). Figure 3A and Figure 3B Based on 1000 bootstrap repetitions, the bias-corrected 95% confidence intervals for both analytes were zero, indicating that the changes in mBDNF and proBDNF concentrations in cerebrospinal fluid and plasma were largely independent. This supports their separate evaluation in postpartum depression biomarker studies, rather than substitution or mixed detection.

[0062] 4. Security Assessment

[0063] Among adverse events, only chest tightness (2.8% vs 13.6%, P=0.02, RR [95% CI]: 4.32 [1.25, 14.90]) and blurred vision / tinnitus (5.5% vs 18.4%, P=0.02, RR [95% CI]: -6.24 [3.02 (1.18, 7.74)]) occurred significantly more frequently in the PPD group; the incidence of dizziness, nausea / vomiting, or other rare events did not differ significantly. One case of postpartum fever occurred in the nPPD group, and one case of pneumonia occurred in the PPD group (Table 2).

[0064] The above detailed embodiments are merely for illustrating the present invention and should not be construed as limiting the scope of protection of the present invention. Technical solutions described in the embodiments but not claimed in the claims should not be construed as a waiver of patent rights.

Claims

1. The use of mBDNF in the preparation of a reagent for predicting the risk of postpartum depression in the prenatal period, the reagent being used to measure the level of mBDNF in the plasma of a subject.

2. The application of the reagent in the preparation of a kit for predicting the risk of postpartum depression in prenatal prenatal care, wherein, The reagent is used to determine the level of mBDNF in the plasma of the subject.

3. A kit for predicting the risk of postpartum depression in the prenatal period, wherein, The kit contains reagents for determining the level of mBDNF in the plasma of the subject.

4. The application according to claim 2 or the kit according to claim 3, wherein, The kit measures the level of mBDNF in the plasma of the subjects using ELISA.

5. The application according to claim 2 or the kit according to claim 3, wherein, The kit measures the level of mBDNF in the plasma of the subjects using the DuoSet ELISA.

6. The use of proBDNF in the preparation of a reagent for predicting the risk of postpartum depression in the prenatal period, said reagent being used to measure proBDNF levels in the cerebrospinal fluid of a subject.

7. The use of reagents in the preparation of kits for predicting the risk of postpartum depression in prenatal prenatal care, wherein, The reagent is used to determine the level of proBDNF in the cerebrospinal fluid of the subjects.

8. A kit for predicting the risk of postpartum depression in the prenatal period, wherein, The kit contains reagents for determining the level of proBDNF in the cerebrospinal fluid of a subject.

9. The application according to claim 7 or the kit according to claim 8, wherein, The kit measures the level of proBDNF in the cerebrospinal fluid of the subjects using ELISA.

10. The application according to claim 7 or the kit according to claim 8, wherein, The kit measures the proBDNF level in the cerebrospinal fluid of the subjects using the DuoSet ELISA.

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