Major depressive disorder (MDD) is a serious mental disorder with unclear pathogenesis. ProBDNF is a precursor protein of brain derived neurotrophic factor (BDNF) expressed in the central nervous system and peripheral tissues. Previous studies showed that blood proBDNF levels in MDD were increased. However, the relationship between proBDNF/p75NTR and inflammatory cytokines in peripheral blood of MDD is unknown. The current study examined the expression of proBDNF and inflammatory markers in patients with major depression. Peripheral blood mononuclear cells (PBMCs) and serum were obtained from depressive patients (n = 32) and normal donors (n = 20). We examined the mRNA and protein expression of proBDNF/p75NTR/sortilin signaling pathway, as well as tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10) in human PBMCs. The Enzyme-Linked Immunosorbent Assay (ELISA) levels of these factors in the sera were also examined. Furthermore, the correlations between each factor and severity of major depression were tested. Of biomarkers studies, we found that proBDNF, p75NTR and sortilin production were significantly increased in PBMCs from MDD patients compared with that from the normal donors. The upregulation of p75NTR in PBMCs was most obvious as determined by qPRC and Western blots. Interestingly, the expression of proBDNF/p75NTR/sortilin signaling pathway in PBMC could be reversed after therapeutic management. Inflammatory cytokines in PBMC from MDD patients were also increased. Consistently, ELISA showed that the levels of p75NTR, sortilin, IL-1β and IL-10 in the serum of major depression were also increased compared with normal donors, and positively correlated with the major depression scores. The levels of IL-1β and IL-10 were also positively correlated with the major depression scores. Intriguingly, the levels of sortilin was positively correlated with IL-1β. Further flow cytometry studies showed that the number of proBDNF and p75NTR positive CD4+, CD8+ T cells and CD19+ B cells from MDD patients was increased and subsequently reversed after therapeutic management. The findings suggest that the upregulation of proBDNF/p75NTR/sortilin signaling pathway may relate to inflammatory markers in patients with major depression. Our data also suggest that proBDNF/p75NTR/sortilin signaling pathway may serve as biomarkers for MDD.
Research Article
Correlations between proBDNF/p75NTR and inflammatory markers in patients with major depression
https://doi.org/10.21203/rs.3.rs-2113445/v1
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major depression disorder
proBDNF
p75NTR
sortilin
inflammatory markers
Major depression disorder (MDD) is a common and complex disease, affecting approximately 3.5 billion population all over the world (Malhi and Mann 2018). The World Health Organization suggests that the disease ranks as the second cause of burden due to loss of work capacity and mortality, and will rank first by 2030 (Global, regional, and national burden of 12 mental disorders in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019 2022). The suicide rate of depression patients is 36 folds that of the general population, causing serious harm to patients, families and society (Janackovski, Deane, and Hains 2021). Thus, major depression is still one of the major diseases that need to be focused on prevention and further research. Our previous study found neurotrophins have been implicated in the pathophysiology of depression (Bai et al. 2016). Furthermore, inflammatory cytokines were increased in the many depressed patients (Beurel, Toups, and Nemeroff 2020). Therefore, whether the neurotrophin signaling correlates to inflammatory cytokine response in major depression remains unclear.
Neurotrophins (nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and the neurotrophins NT-3 and NT-4) play essential roles in neuron survival, plasticity, neurogenesis, and synaptogenesis as well as various non-neuronal functions (Quesseveur et al. 2013; Luo et al. 2020). Neurotrophins bind to their specific high-affinity or low-affinity receptors tyrosine kinase A (Trk A), Trk B, Trk C and p75 pan-neurotrophin receptor (p75NTR) that binds to all ligands. Among the neurotrophins, BDNF is the most widely expressed and closely correlated with major depression (Casarotto et al. 2021; Yang, Zhang, et al. 2020). The down-regulation of BDNF is involved in the pathophysiology of major depression and antidepressant drugs can restore the BDNF level (Casarotto et al. 2021). In recent years, not only has mature BDNF been a research hotspot for neuroimmunological scientists, but its precursor protein (proBDNF) has also attracted much attention in the pathogenesis of major depression (Luo et al. 2019; Zhou et al. 2013). ProBDNF is synthesized by the BDNF gene and secreted from different monocytes (Shen et al. 2020). For a long time, proBDNF has been regarded as a single protein precursor molecule without biological activity. In particular, many studies show that proBDNF is increased in major depression and elicits opposing effects to that of BDNF via binding p75NTR and co-receptor sortilin to mediate neuronal apoptosis, neurite collapse, inhibition of neurogenesis and activated inflammatory response (Sun et al. 2012; Li et al. 2017; Ho et al. 2019; Hu et al. 2021). The “neurotrophin hypothesis” of depression holds that the balance between BDNF and proBDNF plays a pivotal role in the pathogenesis of depression. Although the proBDNF/p75NTR/sortilin hypothesis of depression has been postulated in the central nervous system, the role of proBDNF in the peripheral immune system in depression is unknown.
Inflammatory processes have been implicated in the pathophysiology of depression. In the past 20 years, accumlating evidence shows that inflammatory activation and pro-inflammatory states play a pathological role in depression, as reflected by increased inflammatory markers, increased number of immune cells, and abnormal antibody titers (Beurel, Toups, and Nemeroff 2020; Klawonn et al. 2021). Under the action of stress, different pro-inflammatory markers (TNF-α, IL-1β, IL-6, IL-17) and anti-inflammatory markers (IL-10, IL-4, IL-35) are expressed in cerebrospinal fluid and peripheral blood (Kohler et al. 2018). Syed et al. found that 18 pro-inflammatory and anti-inflammatory cytokine levels were increased, and 6 decreased in depressed patients compared with healthy by ELISA, which demonstrated an activated inflammatory response (Syed et al. 2018). They also found antidepressant drugs could remodel the inflammatory response in the depressed patients. Compared with the control group, the expression of mRNA and protein levels of TNF-α, IL-1β and IL-6 in the prefrontal cortex of the depressed individuals who died by suicide was increased in an autopsy study (Pandey et al. 2018). Epidemiological studies showed that many inflammation-related diseases were prone to suffer from major depression, such as postpartum, diabetes, stroke, and autoimmune diseases (Vallerand et al. 2018).The possible mechanism of inflammatory cytokines that result in depression is that they may break the blood-brain barrier, enter into the central nervous system and activate microglia and astrocytes, affecting the synthesis and the secretion of monoamine neurotransmitters, and the release of neurotrophins (Kohler et al. 2018; Pandey et al. 2018). The relationship of depression and inflammation is bidirectional interaction and form a positive feedback loop. Therefore, blocking the release of peripheral inflammatory is a key to achieve alleviation of depression.
We have previously shown that the balance between the proBDNF/p75NTR/sortilin and mBDNF/TrkB signaling pathways appears dysregulated in major depression (Zhou et al. 2013). The proBDNF/p75NTR/sortilin signaling pathway regulates neurosynaptic plasticity and promotes that the occurrence of depression in central nervous system (Bai et al. 2016). We further found that injection of anti-proBDNF in anterior cingulate cortex (ACC) or injection of proBDNF scavenger p75ECD-Fc molecules reversed chronic stress induced adverse mood behaviors in mice (Yang et al. 2017; Lin, Zhou, and Bobrovskaya 2021). Subsequently, it was proposed that antidepressant drugs correct the imbalance between proBDNF/p75NTR/sortilin and mBDNF/TrkB in the brain of chronically stressed mice (Yang, Zhang, et al. 2020). Our previous research mainly focused on proBDNF/p75NTR/sortilin and mBDNF/TrkB signaling pathway in the central nervous system in regulating synaptic plasticity. However, the exact mechanism of proBDNF/p75NTR/sortilin signaling pathway in peripheral immune regulation in major depression is unclear.
In the present study we aimed to clarify relationships between proBDNF/p75NTR/sortilin signaling pathway and inflammatory cytokines in patients with major depression. Using PBMCs and serum from depressive patients and controls, we showed that there are significant correlations between proBDNF/p75NTR/sortilin expression levels and the disease severity or between expression levels of proBDNF/p75NTR/sortlin and cytokines.
Human Subjects
Thirty-two patients, 18–60 years old, both male and female, were recruited from Tianjin Mental Health Center in this study (n=32). Major depression was diagnosed according to the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) criteria. The inpatients of Tianjin Mental Health Center met the 21-item Hamilton Rating Scale for depression (HRSD-21) score≥25 points. Psychotherapy, drug treatment (antipsychotics or antidepressants or the combination), transcranial magnetic stimulation (TMS) or modified electro-convulsive therapy (MECT) are all effective. The control population consisted of twenty healthy age- and gender-matched volunteers at the Second Hospital of Tianjin Medical University (n=20) (Table 1). We declared that our study was carried out in accordance with the latest version of the Declaration of Helsinki. The Ethics Committee of Tianjin Mental Hospital approved all procedures (KY2018K015). Patients were enrolled to participate in the study after they had signed the informed consents for participation. The patients were all drug-naive. We have excluded the participants who had history of autoimmune diseases, chronic inflammatory diseases, or other immune-associated disorders in this study.
Clinical blood sampling
Likewise, clinical assessments and blood collection were all performed. After having obtained the permission, peripheral blood samples were collected from healthy volunteers and patients. The coagulant vacuum blood collection tubes and anticoagulation blood collection vacuum tubes with Complete Proteinase Inhibitor Cocktail, plasminogen activator inhibitor 1 (PAI-1) and the furin inhibitor I were used to get 3 ml peripheral blood individually. Blood was obtained from the antecubital vein fasting in anti-coagulant tubes (light green tubes) and kept at 4 °C. The human lymphocytes separation medium (cat.KGA830, Tianjin, China) was used to separate the PBMCs using standard protocol from the blood and kept in −80 °C before total RNA and protein extraction. Human blood obtained from the antecubital vein was collected in coagulant tubes (light yellow tubes) and kept on ice for 4 h, and then centrifuged at 12000 rpm, 4 °C for 5 min. The serum (top layer with light yellow color) was carefully collected and stored at −80 °C before further experiment.
Quantitative real-time PCR
Total RNA was extracted from the synovial tissue of rodents, and peripheral blood mononuclear cells (PBMCs) from participant donors, which were extracted by TRIzol® reagent (Sigma), following the manufacturer’s recommendation. The RNA samples were dissolved in 30 μl of DEPC-H2O and subsequently stored at − 80 °C. The cDNA was obtained using the reverse transcription kit (Thermo- Fisher Scientific, CA, USA). Quantitative real-time PCR was performed with SYBR Green (Takara, Japan) on CFX96 TouchTM Deep Well Real-Time PCR Detection system (Bio-Rad Laboratories, Inc., Hercules, CA, USA). Q-PCR was performed as follows: 95 °C for 3 min, and 39 cycles of 95°C for 10s and 60°C for 30s. The experiment was repeated in triplicate. Gene expression level of p75NTR and sortilin were detected by running quantitative real-time PCR. The gene expression of β-actin/GAPDH was detected as internal control for total RNA used. Data were processed using the 2-ΔΔCTmethod. The primer sequences used and more details were illustrated as described previously (Yang et al. 2022).
Western blotting analysis
Protein was extracted from PBMCs from participant donors harvested using radio immunoprecipitation assay (RIPA) lysis buffer supplemented with proteinase inhibitors. Protein concentrations were measured using the BCA Protein Assay Kit (Thermo Scientific, Waltham, MA). Equal amounts of protein were separated by 10% SDS/PAG, followed by immunoblotting with the primary antibodies (sheep anti-human proBDNF 1:200, from professor Xin-Fu Zhou’s laboratory; mouse CD271 antibody 1:1000, cat. 14-9400-82, Invitrogen, USA; mouse sortilin 1:1000, cat.#AF3154-SP, CoWin Biosciences, China; mouse TNF-α 1:500, cat. SRP13543, China; mouse IL-1β 1:500, cat. SRP05257, China; mouse IL-6 1:500, cat. SRP05348, China; anti-human IL-10 antibody 1:1000, cat. 506801, Biolegend; rabbit anti-GAPDH antibody, 1:5000, cat.#ab 9485, abcam, China). Membranes were then incubated with peroxidase-conjugated secondary antibody. Western blotting band were analyzed by the mean grey value with NIH Image J 7.0 and standardized to GAPDH control protein.
Enzyme-Linked Immunosorbent Assay (Isolation of Serum)
Serum was assayed for p75NTR, sortilin, TNF-α, IL-1β, IL-6 and IL-10 in duplicate, using ELISA assay kit (p75NTR, ab155436; sortilin, MM-1983H1; TNF-α, MM-0122H1; IL-1β, MM-0181H1; IL-6, EK0410; IL10, MM-0066H1), according to the protocol provided by the manufacturer. Briefly, ELISA plates were coated with protein G-purified mouse monoclonal antibody (2 μg/ml in coating buffer), blocked with PBS-BSA, loaded with serum at 1:5 dilution, detected with detection antibodies, and incubated with TMB, and OD values were obtained at 450 nm.
Flow cytometry
To measure the proBDNF and p75NTR expression in PBMCs from healthy volunteers and major patients, human PBMCs were isolated from peripheral blood samples of normal donors and major depressive patients by lymphoprep separation liquid (Stemcell Technology, Norway). Freshly isolated PBMCs were then counted manually with a hemocytometer, and cell viability was measured by trypan blue (> 96%). PBMCs were stained with fluorescently conjugated monoclonal antibodies (mAbs) at 4 °C for 30 min as follows, respectively: ECD anti-human CD4 (cat.#ab6604727, BC), APC-CY7 anti-human CD8 (cat.#ab641400, BD), FITC anti-human CD20 (cat.#ab347673, BD), PC7 anti-human CD19 (cat.#abIM3628, BC), APC anti-human CD271 (p75NTR/NGFR, cat.#ab400119, Biolegend), and APC mouse IgG1(cat.#ab400119, Biolegend). After rinse, cells were read on the flow cytometer (Cystek, Fremont, CA, USA), and data were analyzed with FlowJo vX0.7 software. Single-stained cells or OneComp eBeads (eBioscience, San Diego, CA) were used for compensation calculations. Unstained cells, cells with 7-AAD, and fluorescence minus one (FMO) controls were used for cytometry and gating set up.
Statistical analysis
Data were analysed using mean ± S.D. Statistical Package for the Social Science v.13 and graphically presented using Prism 8 softwares. Paired or unpaired two-tailed Student’s t test, one-way ANOVA followed by Dunnett’s/Tukey’s Multiple Comparison post test or two-way ANOVA with Bonferroni’s Multiple Comparison post hoc test were used for mean comparisons, respectively. The Spearman’s correlation test was used for analyzing the correlations of HRSD scores with p75NTR, sortilin, TNF-α, IL-1β and IL-10 levels in the depressed serum. P < 0.05 was taken to indicate statistical significance.
Twenty normal donors, thirty-two patients with major depression, and thirty-two treated patients, ages 18-60 years, were recruited. Demographic and clinical characteristics are presented in Table 1. No significant differences were found among groups with regard to sex, age, and white blood cells. After treatment, the HRSD-21 scores were dramatically reduced in treated group compared with prior treatment by paired two-tailed Student’s t test (p<0.01).
ProBDNF/p75NTR/sortilin Signaling was Activated in Patients with Major Depression
ProBDNF preferentially binds to its co-receptors (p75NTR and sortilin) not only to perform the cascade roles in neuronal apoptosis, but also to regulate various inflammatory diseases by activating the functions of monocytes, macrophages or microglia. The lymphocyte mRNA levels of p75NTR (p=0.0001, t=10.28, Fig.1A) and sortilin (p=0.0007, t=7.886, Fig.1B) were statistically different from those in the depressed group (n=32) compared to the normal group (n=20). Moreover, the lymphocyte protein levels of proBDNF (p=0.0037, t=5.724, Fig.1D), p75NTR (p=0.0031, t=5.908, Fig.1E), and sortilin (p=0.0056, t=5.27, Fig.1F) were significantly higher in the depressed group than in the normal group. After treatment, the levels of proBDNF (protein: p=0.0024, t=6.204, Fig.1D), p75NTR (mRNA: p=0.0006, t=8.135, Fig.1A; protein: p=0.0038, t=5.686, Fig.1E), and sortilin (mRNA: p=0.006, t=5.202, Fig.1B; protein: p=0.043, t=3.41, Fig.1F) were reduced not only in the mRNA but also in the protein in the treated group than prior treatment. As shown in Fig. 3, through ELISA methods, we further analyzed changes of serum p75NTR (p<0.0001, Fig. 3A) and sortilin (p=0.0123, Fig. 3B) levels, which were consistent to changes of mRNA and protein in PBMC of the depressed patients. Antidepressant treatment could decrease the serum p75NTR (p<0.0001, Fig. 3A) and sortilin (p=0.0464, Fig. 3B) levels compared to prior treatment. The above results suggest that proBDNF, p75NTR and sortilin were activated in depressed patients, and antidepressant treatment can reverse the activation of proBDNF/p75NTR/sortilin signaling in MDD patients.
Inflammatory Cytokines were Activated in Patients with Major Depression
More and more evidence show that brain cell inflammation is related to depressive behavior. The protein levels of TNF-α (p=0.0033, Fig. 2B), IL-1β (p=0.0053, Fig. 2C), IL-6 (p=0.0124, Fig. 2D) and IL-10 (p<0.0001, Fig. 2E) from lymphocytes were significantly increased in depressed group when compared with normal donors. Through the ELISA methods, we also found upregulated IL-1β and IL-10 level in depressed group. The serum levels of TNF-α (p=0.0614, Fig. 3C), IL-1β (p=0.0019, Fig. 3D), IL-6 (p=0.2107, Fig. 3E) and IL-10 (p=0.0004, Fig. 3F) were significantly increased in depressed group when compared with normal donors. After treatment, the protein levels of TNF-α (p=0.0153, Fig. 2B), IL-1β (p=0.0557, Fig. 2C), IL-6 (p=0.0368, Fig. 2D) and IL-10 (p<0.0001, Fig. 2E) from lymphocytes were dramatically reduced in treated group compared with prior treatment. Moreover, the serum levels of TNF-α (p=0.0203, Fig. 3C), IL-1β (p=0.0036, Fig. 3D), IL-6 (p=0.2107, Fig. 3E) and IL-10 (p<0.0001, Fig. 3F) were also decreased after the treatment. These results suggested that inflammatory cytokines were activated in patients with major depression.
The Levels of proBDNF/p75NTR/sortilin in Lymphocytes and Serum were Positively Correlated with HRSD-21 Scores
We analyzed the relationship between the protein levels of proBDNF/p75NTR/sortilin in lymphocytes and HRSD-21 scores. The data showed that the levels of proBDNF, p75NTR and sortilin in lymphocytes were positively correlated with HRSD-21 scores in the depressed group (n=32; proBDNF: r=0.4387, p=0.012, Fig. 1G; p75NTR: r=0.5734, p=0.0006, Fig. 1H; sortilin: r=0.4065, p=0.021, Fig. 1I; Spearman’s correlation test). The Spearman’s correlation test also showed that the serum level of p75NTR (r=0.4725, p=0.0063, Fig. 4A) and sortilin (r=0.359, p=0.0436, Fig. 4B) were positively correlated with HRSD-21 scores. These results suggested that proBDNF/p75NTR/sortilin signaling pathway might had positive correlations with the major depression severity.
No significant Correlation was Found Between Inflammatory Cytokines and HRSD-21 Scores, but there were Positive Correlations Between Inflammatory Cytokines with Sortilin
We analyzed the relationship between the HRSD-21 scores and the serum levels of inflammatory cytokines. The data showed that there was no correlation between HRSD-21 scores and serum levels of TNF-α (r=-0.3335, p=0.0621, Fig. 4C), IL-6 (r=-0.08881, p=0.6289, Fig. 4E), IL-1β (r=0.1017, p=0.5798, Fig. 4D) or IL-10 (r=0.1599, p=0.3821, Fig. 4F) in the depressed group. We further analyzed the relationship between the serum levels of the inflammatory cytokines and p75NTR/sortilin in the depressed group. The results showed that there is no significant correlation between the p75NTR level and the level of TNF-α (r=0.03469, p=0.8505, Fig. 4G), IL-1β (r=0.1234, p=0.5009, Fig. 4H), or IL-10 (r=0.04317, p=0.8145, Fig. 4J). We also analyzed the relationship between sortilin and the inflammatory cytokines in the serum. Interestingly, the data showed that the sortilin level had a positive correlation with the level of IL-1β (r=0.5002, p=0.0036, Fig. 4L), but not with TNF-α (r=0.2532, p=0.162, Fig. 4K), IL-6 (r=0.3245, p=0.07, Fig. 4M) or IL-10 (r=0.1686, p=0.3562, Fig. 4N).
Evaluation of Serum p75NTR as a Diagnostic Marker for Major Depression
The 21-item Hamilton Rating Scale for Depression (HRSD-21) score was denoted for depression was as mild (<35 points) and severe (≥35 points). The HRSD scores of major depressive groups were range 29-47, mean ± SD=37.81±4.8 (Table 1). Among 32 patients with major depression, 22 cases were severe (72.9%). As p75NTR, sortilin and inflammatory cytokines in serum were significantly increased in major depressed patients, we further investigated their diagnostic value for MDD. The AUCs of p75NTR, sortilin, IL-1β, IL-10, IL-6 and TNF-α for major depression were 0.9391 (p<0.0001; 95%CI, 0.8783-0.9999), 0.6172 (p=0.1583; 95%CI, 0.4639-0.7705), 0.8891 (p<0.0001; 95%CI, 0.7946-0.9836), 0.8758 (p<0.0001; 95%CI, 0.7779-0.9737 ), 0.6539 (p=0.0639; 95%CI, 0.5043-0.8035), and 0.6156 (p=0.164; 95%CI, 0.4563-0.775), respectively (Fig.5, Table 2). The optimal p75NTR cut-off point for major depression was 48.56 pg/ml with a sensitivity and specificity of 87.5% and 90%, respectively, demonstrating a good clinical diagnostic value. Additionally, evaluation of serum IL-1β and IL-10 cut-off point for major depression were 21.6 pg/ml and 183.5 pg/ml, respectively, which also generated significant diagnostic value.
Expression Pattern of proBDNF/p75NTR in Peripheral Immune Cells
Many studies reported that inflammation and immune disorder were widely observed in major depression (Beurel, Toups, and Nemeroff 2020; Klawonn et al. 2021). Our previous observation showed that major depressive patients exhibit significantly lower percentage of CD45+ lymphocytes (Yang, Ning, et al. 2020). In this study, we measured the expression pattern of proBDNF/p75NTR on T/B cells from normal donors (n=20), prior treatment (n=32), and treated patients (n=32). As shown in Fig.6, proBDNF/p75NTR could be detected on both T and B lymphocytes. We investigated the MFI of proBDNF in the CD4+ T cells (t=2.608, p=0.012, Fig.6C) and CD8+ T cells (t=3.066, p=0.0035, Fig.6D) was significantly increased in major depressive patients compared to normal group. While the MFI of proBDNF in the CD19+ B cells (t=1.69, p=0.0972, Fig.6E) and CD20+ B cells (t=0.7134, p=0.4789, Fig.6F) was not different in major depressive patients compared to normal group. After treatment, the MFI of proBDNF in the CD4+ T cells (t=3.316, p=0.0023, Fig.6C), CD8+ T cells (t=3.948, p=0.0004, Fig.6D), CD19+ B cells (t=2.596, p=0.0143, Fig.6E) and CD20+ B cells (t=2.643, p=0.013, Fig.6F) was downregulated compared to prior treatment. Consistent with proBDNF, the MFI of p75NTR in the CD4+ T cells (t=5.269, p=0.0001, Fig.6G), CD8+ T cells (t=3.693, p=0.0005, Fig.6H), or CD19+ B cells (t=2.604, p=0.0121, Fig.6I) was also significantly higher in major depressive patients than that from the normal group but there was no difference in CD20+ B cells (t=0.7522, p=0.4555, Fig.6J). After treatment, the MFI of p75NTR in the CD4+ T cells (t=2.359, p=0.0248, Fig.6G), CD8+ T cells (t=3.32, p=0.0023, Fig.6H), CD19+ B cells (t=3.071, p=0.0041, Fig.6I) and CD20+ B cells (t=2.934, p=0.0063, Fig.6J) was downregulated compared to prior treatment. The increased expression of proBDNF/p75NTR signaling in peripheral lymphocytes in major depressive patients supported a possible role of proBDNF/p75NTR in depressive progression.
Differentially Expressed Genes Showing Enrichment by Way of Pathway Analysis
We studied mRNAs that were noticeably altered between normal donors (n=6) and depressed patients (n=7). In order to get a better knowledge of the inherent processes in major depression, pathway analyses were performed for up-regulated mRNAs exhibiting ≥ two-fold-change and identified known and important pathways in major depression. The aberrantly activated pathways as shown in Fig.7. For pathway analyses, mRNAs that were differentially expressed in the leading forty pathways dysregulated, particularly in signal transduction and immune system.
Several important findings emerged from the present study. First, the peripheral upregulation of proBDNF and its receptors in major depressive patients is accordance with previous studies, and the proBDNF signaling is decreased after antidepressant treatment for major depressive patients (Zhou et al. 2013; Zwolinska et al. 2022). The proBDNF, p75NTR and sortilin levels are positively correlated with the major depression severity. Second, we observed elevated inflammatory cytokine levels in major depressive patients and affirmed that the levels of IL-1β and IL-10 are positively correlated with the major depression severity. Third, we discovered that proBDNF/p75NTR signaling is implicated in the immune cell dysfunction, especially in CD4+, CD8+ T cells and CD19+ B cells of major depression. Hence, we propose that higher proBDNF/p75NTR/sortilin signaling pathway may be related to inflammatory markers in patients with major depression.
The Expression Of Probdnf, P75ntr, And Sortilin
Suicide attempts are the main complications of major depressive episodes. Under a vary kind of chronic or acute stresses, the genes that make individuals vulnerable or resistant to the depression are all changed. Numerous studies showed decreased expression of BDNF in both protein and mRNA levels of postmortem brains of suicide victims and they were diagnosed as major depression (Erbay et al. 2021; Banerjee et al. 2013; Hashimoto 2010). BDNF is initially synthesized as a precursor protein proBDNF, and then proBDNF is proteolytically cleaved to the mature BDNF (mBDNF). More researches point to the importance of imbalance between mBDNF and proBDNF signaling pathway in the pathophysiology of mood depressive disorder (Hashimoto 2010; Gelle et al. 2021). The function of proBDNF is different from that of mBDNF, which has opposite effects to mBDNF (Sun et al. 2012). Our previous studies found that proBDNF and its receptors levels were significantly upregulated in the blood of depressive patients and animal models (Yang, Zhang, et al. 2020; Zhou et al. 2013). Especially, one recent paper reported proBDNF levels were decreased significantly after treatment, while mBDNF levels were not altered (Zwolinska et al. 2022). Our results on proBDNF and its receptors levels in PBMCs and serum were consistent with these studies. The proBDNF, p75NTR and sortilin levels are positively correlated with the major depression severity. Elevated proBDNF and its receptors can be used as novel biomarkers for depression, and a downregulation in serum proBDNF and its receptors levels could be considered as an indicator of recovery after treatment.
Expression Pattern Of Probdnf/p75ntr In Peripheral Immune Cells
Immunological mechanisms and inflammation are increasingly implicated in the pathogenesis of depressive symptoms. Some reports suggest that activation of the peripheral immune system has been consistently associated with depression (Chamberlain et al. 2019; Vasileva et al. 2019). Depression can cause T/B lymphocytes imbalance and functional decline of natural killer T (NKT) cells, subsequently leading to low immune function, infection susceptibility, tumor formation, and other diseases (Boorman et al. 2016). In addition, stress-induced metabolic disorder in peripheral CD4+ T cells leads to anxiety-like behavior, and the lack of CD4+ T cells protects mice with xanthine metabolic disorder from stress-induced anxiety-like behavior, implying that CD4+ T cells can trigger anxiety-like behavior (Fan et al. 2019). Consistent with our previous observation, major depressive patients exhibit significantly lower percentage of CD45+ lymphocytes and elevated CD4+CD8−-CD3+ T cells with decreased CD4−CD8+-CD3+ T cells (Yang, Ning, et al. 2020). A recent paper reported depressive disorders were associated with increased peripheral blood cell deformability (Walther et al. 2022). Moreover, a largest transcriptome-wide association study (TWAS) for postpartum depression confirmed that B cells had a majority of transcriptome-wide significant changes, implicating altered B-cell activation and insulin resistance (Walther et al. 2022).
Previous studies have demonstrated the upregulation of proBDNF and its receptor p75NTR in macrophages, monocytes, lymphocytes and microglia in a variety of neurological conditions, including spinal cord injury, multiple sclerosis, lipopolysaccharide(LPS)-induced sepsis, lupus erythematous (Luo et al. 2020; Shen et al. 2022) and Toxoplasma infection (Hu et al. 2021; Klawonn et al. 2021; Dusedau et al. 2019). Only a few studies found that BDNF and proBDNF can be released from B cells and T cells, contributing to B cell development or survival, and T cell maturation (Schuhmann et al. 2005; Linker et al. 2015). No studies evaluating proBDNF and p75NTR with regard to PBMCs have been reported in major depressive patients. In the current study, we first examined the proBDNF and p75NTR expression in peripheral blood PBMCs from major depressive patients by flow cytometry. ProBDNF expression was increased in all tested immune cells, including CD4+CD8−-CD3+ T cells and CD4−CD8+-CD3+ T cells from major depressive patients, compared to normal donors. Besides, p75NTR was also upregulated in CD4+CD8−-CD3+ T cells, and CD4−CD8+-CD3+ T cells, as well as CD19+B cells in depressive patients. After treatment, the increased expression of proBDNF and p75NTR can be downregulated and returned to normal level, even persistently decreased. This contention was supported by the observation that proBDNF signaling was persistently elevated both on circulating T cells and B cells in patients with major depression, predominantly expressed on T cells. Several reports demonstrated that the downstream signaling of prBDNF/p75NTR involves the signal pathways of RhoA, JNK and NF-κB (Sun et al. 2012; Charalampopoulos et al. 2012; Saadipour et al. 2018). Therefore, the proBDNF/p75NTR signaling may be related to various immune functions in depression.
The Expression Of Tnf-α, Il-1β, Il-6 And Il-10
Over the past two decades, there has been growing evidence that MDD is associated with a systemic immune activation, comprising of abnormalities in inflammatory markers, immune cell numbers, and antibody titers (Beurel, Toups, and Nemeroff 2020; Gibney and Drexhage 2013). Thus, inflammatory processes have been implicated in the pathophysiology of depression. Many reports demonstrate that pro-inflammatory cytokines are increased in MDD patients, with a fairly unanimous consensus of increases in TNF-α, IL-1β, IL-6 in both blood and CSF of MDD patients compared to healthy controls (Kohler et al. 2018; Kohler et al. 2017; Kim et al. 2007). In contrast, some other studies found IL-10 was reduced in MDD patients (Kohler et al. 2018; Dhabhar et al. 2009). Lower IL-10 levels, as an anti-inflammatory cytokine, in MDD likewise was unexpected. However, a previous study did find higher IL-10 related to depression and had a positive association with IL-6 (Wiener et al. 2019). In the present study, we examined the protein expression of TNF-α, IL-1β, IL-6 and IL-10 in human PBMCs and serum levels. Using the western blot method or ELISA, we found consistent increases in IL-1β and IL-10 in both PBMCs and serum in depressive patients compared to healthy donors. In addition, we found that the increase in TNF-α and IL-6 is more obvious in the PBMCs than in the serum. However, the inconsistent changes of TNF-α and IL-6 in PBMC and in serum might be due to the different sensitivities between the detection methods (Maes et al. 2012). We found that the levels of inflammatory cytokines in major depressive patients were reduced after antidepressant treatment but did not find any relationship between inflammatory cytokines and the depression severity.
Correlation Between Probdnf/p75ntr Signaling Molecules And Inflammatory Cytokines
The two most consistent and salient biologic risk factors in the pathogenesis of depression are neurotrophins and chronic low-grade inflammation. Reduced BDNF and increased proinflammatory cytokine in MDD have received considerable attention (Porter and O'Connor 2022). Both proBDNF and mBDNF forms of the BDNF protein are neuroactive, though the activity of proBDNF and mBDNF have largely opposite effects. ProBDNF/p75NTR signaling activates transcription factor NF-κB promoting inflammation and apoptosis (Hu et al. 2021; Saadipour et al. 2018). In this study, no significant correlation was found between p75NTR and TNF-α, IL-1β, IL-6 or IL-10. However, we did find that the sortilin levels were positively correlated with TNF-α, IL-1β, IL-6 and IL-10, especially IL-1β. Interestingly, we found that the serum p75NTR, IL-1β and IL-10 were excellent diagnostic biomarkers for major depression with the sensitivity reaching 48.56 pg/ml, 21.6 pg/ml and 183.5 pg/ml, respectively. The results revealed that proBDNF/p75NTR signaling were also associated with increased inflammatory cytokines levels in the periphery of depression. Our recent studies also showed that proBDNF/p75NTR promoted rheumatoid arthritis and inflammatory response by activating proinflammatory cytokines (Yang et al. 2022). It is known that rheumatoid arthritis is a high prevalent risk factor for MDD (Zhang 2021). Taken together, proBDNF released from active immune cells perhaps exert its biologic effect on T cells and B cells through autocrine or paracrine effects in the pathogenesis of depression and chronic inflammation (Hu et al. 2021).
Limitations
The study has several limitations need to be considered. Firstly, we need to research specific ELISA assay for proBDNF and measure the serum proBDNF levels. Secondly, we will detect upregulation of proBDNF and its receptor p75NTR in human lymphocytes following treatment with various stimulants in order to search essential effects for B or T cell in depression pathogenesis. Last but not least, we did not measure the expression of NF-κB (nuclei p65, PCNA), RhoA, p-JNK and JNK in the lymphocytes, so we do not know whether proBDNF plays a role in the downstream effectors in depression. These will be what our future study will focus on.
In summary, proBDNF/p75NTR/sortilin signaling is upregulated in the serum and PBMCs of major depressive patients, and the upregulation is attenuated after antidepressant treatment. The expression of proBDNF and its receptor p75NTR is mainly increased in CD4+T, CD8+T and CD19+B cells in major depressive patients. The high expression of inflammatory cytokines in the serum and lymphocytes were positively correlated with sortilin. Our study suggests proBDNF/p75NTR/sortilin signaling in lymphocytes may be involved in the inflammatory immune response in depression. The significance of proBDNF/p75NTR/sortilin signaling in the pathogenesis of depression requires further investigation.
Authors’ Contributions Chun-Rui Yang and Xin-Fu Zhou were involved in conceptualization. Rui Liang and Fan-Jie Meng were involved in data curation. Xiao-Yang Zhang was involved in formal analysis. Chun-Rui Yang, Rui Liang and Zhi-Qiang Wang were involved in funding acquisition. Ning Li was involved in investigation. Liu Yuan and Fan-Jie Meng were involved in methodology. Chun-Rui Yang, Rui Liang, and Fan-Jie Meng were involved in writing—original draft. Fiona-H Zhou, Xin-Fu Zhou and Shuang Liu were involved in supervision. Chun-Rui Yang and Shuang Liu were involved in writing—review and editing. All authors revising the manuscript critically for important intellectual content. All authors have read and agreed to the published version of the manuscript.
Funding Information This research was supported by grant from Science & Technology Development Fund of Tianjin Education Commission for Higher Education (2018KJ086), Youth Fund of the Second Hospital of Tianjin Medical University (2020ydey06, 2020ydey20), and the Tianjin Municipal Natural Science Foundation (21JCYBJC01730).
Data Availability The data used to support the findings of this study are available from the corresponding author upon request.
Compliance with Ethical Standards
Declaration of interest All authors declare no conflict of interest.
- Bai Y.Y., Ruan C.S., Yang C.R., Li J.Y., Kang Z.L., Zhou L., Liu D., Zeng Y.Q., Wang T.H., Tian C.F., Liao H., Bobrovskaya L. and Zhou X.F.(2016) ProBDNF Signaling Regulates Depression-Like Behaviors in Rodents under Chronic Stress. Neuropsychopharmacology 41(12): 2882-2892.
- Banerjee R., Ghosh A.K., Ghosh B., Bhattacharyya S. and Mondal A.C.(2013) Decreased mRNA and Protein Expression of BDNF, NGF, and their Receptors in the Hippocampus from Suicide: An Analysis in Human Postmortem Brain. Clin Med Insights Pathol 6: 1-11.
- Beurel E., Toups M. and Nemeroff C.B.(2020) The Bidirectional Relationship of Depression and Inflammation: Double Trouble. Neuron 107(2): 234-256.
- Boorman E., Zajkowska Z., Ahmed R., Pariante C.M. and Zunszain P.A.(2016) Crosstalk between endocannabinoid and immune systems: a potential dysregulation in depression? Psychopharmacology 233(9): 1591-1604.
- Casarotto P.C., Girych M., Fred S.M., Kovaleva V., Moliner R., Enkavi G., Biojone C., Cannarozzo C., Sahu M.P., Kaurinkoski K., Brunello C.A., Steinzeig A., Winkel F., Patil S., Vestring S., Serchov T., Diniz C., Laukkanen L., Cardon I., Antila H., Rog T., Piepponen T.P., Bramham C.R., Normann C., Lauri S.E., Saarma M., Vattulainen I. and Castren E.(2021) Antidepressant drugs act by directly binding to TRKB neurotrophin receptors. Cell 184(5): 1299-1313 e1219.
- Chamberlain S.R., Cavanagh J., de Boer P., Mondelli V., Jones D.N.C., Drevets W.C., Cowen P.J., Harrison N.A., Pointon L., Pariante C.M. and Bullmore E.T.(2019) Treatment-resistant depression and peripheral C-reactive protein. British Journal of Psychiatry 214(1): 11-19.
- Charalampopoulos I., Vicario A., Pediaditakis I., Gravanis A., Simi A. and Ibanez C.F.(2012) Genetic dissection of neurotrophin signaling through the p75 neurotrophin receptor. Cell Rep 2(6): 1563-1570.
- Dhabhar F.S., Burke H.M., Epel E.S., Mellon S.H., Rosser R., Reus V.I. and Wolkowitz O.M.(2009) Low serum IL-10 concentrations and loss of regulatory association between IL-6 and IL-10 in adults with major depression. Journal of Psychiatric Research 43(11): 962-969.
- Dusedau H.P., Kleveman J., Figueiredo C.A., Biswas A., Steffen J., Kliche S., Haak S., Zagrebelsky M., Korte M. and Dunay I.R.(2019) p75(NTR) regulates brain mononuclear cell function and neuronal structure in Toxoplasma infection-induced neuroinflammation. Glia 67(1): 193-211.
- Erbay L.G., Karlidag R., Oruc M., Cigremis Y. and Celbis O.(2021) Association of BDNF / TrkB and NGF / TrkA Levels in Postmortem Brain with Major Depression and Suicide. Psychiatr Danub 33(4): 491-498.
- Fan K.Q., Li Y.Y., Wang H.L., Mao X.T., Guo J.X., Wang F., Huang L.J., Li Y.N., Ma X.Y., Gao Z.J., Chen W., Qian D.D., Xue W.J., Cao Q., Zhang L., Shen L., Tong C., Zhong J.Y., Lu W., Lu L., Ren K.M., Zhong G., Wang Y., Tang M., Feng X.H., Chai R.J. and Jin J.(2019) Stress-Induced Metabolic Disorder in Peripheral CD4(+) T Cells Leads to Anxiety-like Behavior. Cell 179(4): 864-879 e819.
- Gelle T., Samey R.A., Plansont B., Bessette B., Jauberteau-Marchan M.O., Lalloue F. and Girard M.(2021) BDNF and pro-BDNF in serum and exosomes in major depression: Evolution after antidepressant treatment. Progress in Neuro-Psychopharmacology and Biological Psychiatry 109: 110229.
- Gibney S.M. and Drexhage H.A.(2013) Evidence for a dysregulated immune system in the etiology of psychiatric disorders. J Neuroimmune Pharmacol 8(4): 900-920.
- Global, regional, and national burden of 12 mental disorders in 204 countries and territories, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. 2022) Lancet Psychiatry 9(2): 137-150.
- Hashimoto K.(2010) Brain-derived neurotrophic factor as a biomarker for mood disorders: an historical overview and future directions. Psychiatry and Clinical Neurosciences 64(4): 341-357.
- Ho I.H.T., Liu X., Zou Y., Liu T., Hu W., Chan H., Tian Y., Zhang Y., Li Q., Kou S., Chan C.S., Gin T., Cheng C.H.K., Wong S.H., Yu J., Zhang L., Wu W.K.K. and Chan M.T.V.(2019) A Novel Peptide Interfering with proBDNF-Sortilin Interaction Alleviates Chronic Inflammatory Pain. Theranostics 9(6): 1651-1665.
- Hu Z.L., Luo C., Hurtado P.R., Li H., Wang S., Hu B., Xu J.M., Liu Y., Feng S.Q., Hurtado-Perez E., Chen K., Zhou X.F., Li C.Q. and Dai R.P.(2021) Brain-derived neurotrophic factor precursor in the immune system is a novel target for treating multiple sclerosis. Theranostics 11(2): 715-730.
- Janackovski A., Deane F.P. and Hains A.(2021) Psychotherapy and youth suicide prevention: An interpretative phenomenological analysis of specialist clinicians' experiences. Clin Psychol Psychother 28(4): 828-843.
- Kim Y.K., Na K.S., Shin K.H., Jung H.Y., Choi S.H. and Kim J.B.(2007) Cytokine imbalance in the pathophysiology of major depressive disorder. Progress in Neuro-Psychopharmacology and Biological Psychiatry 31(5): 1044-1053.
- Klawonn A.M., Fritz M., Castany S., Pignatelli M., Canal C., Simila F., Tejeda H.A., Levinsson J., Jaarola M., Jakobsson J., Hidalgo J., Heilig M., Bonci A. and Engblom D.(2021) Microglial activation elicits a negative affective state through prostaglandin-mediated modulation of striatal neurons. Immunity 54(2): 225-234 e226.
- Kohler C.A., Freitas T.H., Maes M., de Andrade N.Q., Liu C.S., Fernandes B.S., Stubbs B., Solmi M., Veronese N., Herrmann N., Raison C.L., Miller B.J., Lanctot K.L. and Carvalho A.F.(2017) Peripheral cytokine and chemokine alterations in depression: a meta-analysis of 82 studies. Acta Psychiatrica Scandinavica 135(5): 373-387.
- Kohler C.A., Freitas T.H., Stubbs B., Maes M., Solmi M., Veronese N., de Andrade N.Q., Morris G., Fernandes B.S., Brunoni A.R., Herrmann N., Raison C.L., Miller B.J., Lanctot K.L. and Carvalho A.F.(2018) Peripheral Alterations in Cytokine and Chemokine Levels After Antidepressant Drug Treatment for Major Depressive Disorder: Systematic Review and Meta-Analysis. Molecular Neurobiology 55(5): 4195-4206.
- Li J.Y., Liu J., Manaph N.P.A., Bobrovskaya L. and Zhou X.F.(2017) ProBDNF inhibits proliferation, migration and differentiation of mouse neural stem cells. Brain Research 1668: 46-55.
- Lin L., Zhou X.F. and Bobrovskaya L.(2021) Blockage of p75(NTR) ameliorates depressive-like behaviours of mice under chronic unpredictable mild stress. Behavioural Brain Research 396: 112905.
- Linker R.A., Lee D.H., Flach A.C., Litke T., van den Brandt J., Reichardt H.M., Lingner T., Bommhardt U., Sendtner M., Gold R., Flugel A. and Luhder F.(2015) Thymocyte-derived BDNF influences T-cell maturation at the DN3/DN4 transition stage. European Journal of Immunology 45(5): 1326-1338.
- Luo L., Li C., Du X., Shi Q., Huang Q., Xu X. and Wang Q.(2019) Effect of aerobic exercise on BDNF/proBDNF expression in the ischemic hippocampus and depression recovery of rats after stroke. Behavioural Brain Research 362: 323-331.
- Luo R.Y., Luo C., Zhong F., Shen W.Y., Li H., Hu Z.L. and Dai R.P.(2020) ProBDNF promotes sepsis-associated encephalopathy in mice by dampening the immune activity of meningeal CD4(+) T cells. J Neuroinflammation 17(1): 169.
- Maes M., Mihaylova I., Kubera M. and Ringel K.(2012) Activation of cell-mediated immunity in depression: association with inflammation, melancholia, clinical staging and the fatigue and somatic symptom cluster of depression. Progress in Neuro-Psychopharmacology and Biological Psychiatry 36(1): 169-175.
- Malhi G.S. and Mann J.J.(2018) Depression. Lancet 392(10161): 2299-2312.
- Pandey G.N., Rizavi H.S., Zhang H., Bhaumik R. and Ren X.(2018) Abnormal protein and mRNA expression of inflammatory cytokines in the prefrontal cortex of depressed individuals who died by suicide. Journal of Psychiatry and Neuroscience 43(6): 376-385.
- Porter G.A. and O'Connor J.C.(2022) Brain-derived neurotrophic factor and inflammation in depression: Pathogenic partners in crime? World J Psychiatry 12(1): 77-97.
- Quesseveur G., David D.J., Gaillard M.C., Pla P., Wu M.V., Nguyen H.T., Nicolas V., Auregan G., David I., Dranovsky A., Hantraye P., Hen R., Gardier A.M., Deglon N. and Guiard B.P.(2013) BDNF overexpression in mouse hippocampal astrocytes promotes local neurogenesis and elicits anxiolytic-like activities. Transl Psychiatry 3: e253.
- Saadipour K., Manucat-Tan N.B., Lim Y., Keating D.J., Smith K.S., Zhong J.H., Liao H., Bobrovskaya L., Wang Y.J., Chao M.V. and Zhou X.F.(2018) p75 neurotrophin receptor interacts with and promotes BACE1 localization in endosomes aggravating amyloidogenesis. Journal of Neurochemistry 144(3): 302-317.
- Schuhmann B., Dietrich A., Sel S., Hahn C., Klingenspor M., Lommatzsch M., Gudermann T., Braun A., Renz H. and Nockher W.A.(2005) A role for brain-derived neurotrophic factor in B cell development. Journal of Neuroimmunology 163(1-2): 15-23.
- Shen W.Y., Luo C., Hurtado P.R., Liu X.J., Luo R.Y., Li H., Hu Z.L., Xu J.M., Coulson E.J., Zhao M., Zhou X.F. and Dai R.P.(2022) Up-regulation of proBDNF/p75(NTR) signaling in antibody-secreting cells drives systemic lupus erythematosus. Sci Adv 8(3): eabj2797.
- Shen W.Y., Luo C., Reinaldo Hurtado P., Hurtado-Perez E., Luo R.Y., Hu Z.L., Li H., Xu J.M., Zhou X.F. and Dai R.P.(2020) The regulatory role of ProBDNF in monocyte function: Implications in Stanford type-A aortic dissection disease. FASEB Journal 34(2): 2541-2553.
- Sun Y., Lim Y., Li F., Liu S., Lu J.J., Haberberger R., Zhong J.H. and Zhou X.F.(2012) ProBDNF collapses neurite outgrowth of primary neurons by activating RhoA. PLoS One 7(4): e35883.
- Syed S.A., Beurel E., Loewenstein D.A., Lowell J.A., Craighead W.E., Dunlop B.W., Mayberg H.S., Dhabhar F., Dietrich W.D., Keane R.W., de Rivero Vaccari J.P. and Nemeroff C.B.(2018) Defective Inflammatory Pathways in Never-Treated Depressed Patients Are Associated with Poor Treatment Response. Neuron 99(5): 914-924 e913.
- Vallerand I.A., Lewinson R.T., Frolkis A.D., Lowerison M.W., Kaplan G.G., Swain M.G., Bulloch A.G.M., Patten S.B. and Barnabe C.(2018) Depression as a risk factor for the development of rheumatoid arthritis: a population-based cohort study. RMD Open 4(2): e000670.
- Vasileva L.V., Ivanovska M.V., Murdjeva M.A., Saracheva K.E. and Georgiev M.I.(2019) Immunoregulatory natural compounds in stress-induced depression: An alternative or an adjunct to conventional antidepressant therapy? Food and Chemical Toxicology 127: 81-88.
- Walther A., Mackens-Kiani A., Eder J., Herbig M., Herold C., Kirschbaum C., Guck J., Wittwer L.D., Beesdo-Baum K. and Krater M.(2022) Depressive disorders are associated with increased peripheral blood cell deformability: a cross-sectional case-control study (Mood-Morph). Transl Psychiatry 12(1): 150.
- Wiener C.D., Moreira F.P., Portela L.V., Strogulski N.R., Lara D.R., da Silva R.A., Souza L.D.M., Jansen K. and Oses J.P.(2019) Interleukin-6 and Interleukin-10 in mood disorders: A population-based study. Psychiatry Research 273: 685-689.
- Yang C.R., Bai Y.Y., Ruan C.S., Zhou F.H., Li F., Li C.Q. and Zhou X.F.(2017) Injection of Anti-proBDNF in Anterior Cingulate Cortex (ACC) Reverses Chronic Stress-Induced Adverse Mood Behaviors in Mice. Neurotox Res 31(2): 298-308.
- Yang C.R., Ding H.J., Yu M., Zhou F.H., Han C.Y., Liang R., Zhang X.Y., Zhang X.L., Meng F.J., Wang S., Li D.D., Sun W.Z., Meng B. and Zhou X.F.(2022) proBDNF/p75NTR promotes rheumatoid arthritis and inflammatory response by activating proinflammatory cytokines. FASEB Journal 36(3): e22180.
- Yang C.R., Ning L., Zhou F.H., Sun Q., Meng H.P., Han Z., Liu Y., Huang W., Liu S., Li X.H., Zheng B., Ming D. and Zhou X.F.(2020) Downregulation of Adhesion Molecule CHL1 in B Cells but Not T Cells of Patients with Major Depression and in the Brain of Mice with Chronic Stress. Neurotox Res 38(4): 914-928.
- Yang C.R., Zhang X.Y., Liu Y., Du J.Y., Liang R., Yu M., Zhang F.Q., Mu X.F., Li F., Zhou L., Zhou F.H., Meng F.J., Wang S., Ming D. and Zhou X.F.(2020) Antidepressant Drugs Correct the Imbalance Between proBDNF/p75NTR/Sortilin and Mature BDNF/TrkB in the Brain of Mice with Chronic Stress. Neurotox Res 37(1): 171-182.
- Zhang C.(2021) Flare-up of cytokines in rheumatoid arthritis and their role in triggering depression: Shared common function and their possible applications in treatment (Review). Biomed Rep 14(1): 16.
- Zhou L., Xiong J., Lim Y., Ruan Y., Huang C., Zhu Y., Zhong J.H., Xiao Z. and Zhou X.F.(2013) Upregulation of blood proBDNF and its receptors in major depression. Journal of Affective Disorders 150(3): 776-784.
- Zwolinska W., Skibinska M., Slopien A. and Dmitrzak-Weglarz M.(2022) ProBDNF as an Indicator of Improvement among Women with Depressive Episodes. Metabolites 12(4).
Table 1
Table 2
ROC curve analysis for diagnostic value of serum parameters. The AUC and the optimal research parameters cut-off points with their relevant validity indexes.
|
Parameter |
AUC |
P |
95%CI |
Cutoff(pg/ml) |
Sensitivity(%) |
Specificity(%) |
|
p75NTR |
0.9391 |
p<0.0001 |
0.878-0.999 |
48.56 |
87.5 |
90 |
|
sortilin |
0.6172 |
p=0.1583 |
0.463-0.770 |
8.781 |
46.9 |
100 |
|
IL-1β |
0.8891 |
p<0.0001 |
0.794-0.983 |
21.6 |
81.3 |
95 |
|
IL-10 |
0.8758 |
p<0.0001 |
0.777-0.973 |
183.5 |
84.4 |
85 |
|
IL-6 |
0.6539 |
p=0.0639 |
0.504-0.803 |
4.015 |
53.1 |
85 |
|
TNF-α |
0.6156 |
p=0.164 |
0.456-0.775 |
10.89 |
71.9 |
50 |
Abbreviations: ROC, receiver operating characteristic; AUC, area under the ROC; 95%CI, 95% confidence interval.
No competing interests reported.