1.Mechanisms of Sini San in Regulation of Gut Microbiota Against Depression and Liver Injury in CUMS Rats
Junling LI ; Yan ZHANG ; Lei WANG ; Fang QI ; Zhenzhen CHEN ; Tianxing CHEN ; Yuhang LIU ; Xueying WANG ; Xianwen TANG ; Yubo LI
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(3):33-40
ObjectiveTo explore the efficacy and mechanisms of Sini San in the treatment of depression and liver injury based on gut microbiota. MethodsThirty-two male Sprague-Dawley (SD) rats were randomly divided into a normal group, model group (M), Sini San group (MS, 2.5 g·kg-1), and fluoxetine group (MF, 2 mg·kg-1). Except for the normal group, rats in the other three groups were subjected to chronic unpredictable mild stress (CUMS). After 8 weeks, the open-field test and sucrose preference test were conducted. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum corticosterone (CORT), adrenocorticotropic hormone (ACTH), corticotropin-releasing factor (CRF), lipopolysaccharide (LPS), Zonulin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), γ-aminobutyric acid (GABA) levels in the hippocampus and prefrontal cortex, and brain-derived neurotrophic factor (BDNF) levels in the hippocampus. Real-time quantitative polymerase chain reaction (Real-time PCR) was used to detect hippocampal BDNF mRNA expression. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured using the ultraviolet lactate dehydrogenase method. The ultrastructure of the intestinal epithelium was observed by electron microscopy, and gut microbiota in rat feces were analyzed using 16S rDNA high-throughput sequencing. ResultsCompared with the normal group, the sucrose preference of rats in the model group was significantly reduced (P0.01), whereas it was significantly increased in the Sini San group compared with the model group (P0.05). Compared with the normal group, hippocampal GABA protein levels and BDNF mRNA expression in the model group were significantly decreased (P0.05), and compared with the model group, both were significantly increased in the Sini San group (P0.05, P0.01). Compared with the normal group, serum LPS and Zonulin levels in the model group were significantly increased (P0.05, P0.01), and compared with the model group, Zonulin levels in the Sini San group were significantly decreased (P0.05). No obvious changes were observed in the ultrastructure of the jejunal mucosa among groups. Compared with the normal group, widened and blurred tight junctions, sparse and shortened microvilli, and mitochondrial swelling with cristae disruption in epithelial cells were observed in the ileal and colonic mucosa of the model group, which were markedly improved in the Sini San and fluoxetine groups. The results of 16S rDNA high-throughput sequencing showed that Sini San improved CUMS-induced dysbiosis of Bacteroidetes and Proteobacteria. Correlation analysis indicated that Bacteroidetes and Proteobacteria were significantly correlated with depression-related indicators, liver function, and intestinal mucosal permeability. ConclusionSini San exerts antidepressant and hepatoprotective effects by improving Bacteroidetes and Proteobacteria and inhibiting the increase in intestinal mucosal permeability in CUMS rats.
2.Mechanisms of Sini San in Regulation of Gut Microbiota Against Depression and Liver Injury in CUMS Rats
Junling LI ; Yan ZHANG ; Lei WANG ; Fang QI ; Zhenzhen CHEN ; Tianxing CHEN ; Yuhang LIU ; Xueying WANG ; Xianwen TANG ; Yubo LI
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(3):33-40
ObjectiveTo explore the efficacy and mechanisms of Sini San in the treatment of depression and liver injury based on gut microbiota. MethodsThirty-two male Sprague-Dawley (SD) rats were randomly divided into a normal group, model group (M), Sini San group (MS, 2.5 g·kg-1), and fluoxetine group (MF, 2 mg·kg-1). Except for the normal group, rats in the other three groups were subjected to chronic unpredictable mild stress (CUMS). After 8 weeks, the open-field test and sucrose preference test were conducted. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum corticosterone (CORT), adrenocorticotropic hormone (ACTH), corticotropin-releasing factor (CRF), lipopolysaccharide (LPS), Zonulin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), γ-aminobutyric acid (GABA) levels in the hippocampus and prefrontal cortex, and brain-derived neurotrophic factor (BDNF) levels in the hippocampus. Real-time quantitative polymerase chain reaction (Real-time PCR) was used to detect hippocampal BDNF mRNA expression. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured using the ultraviolet lactate dehydrogenase method. The ultrastructure of the intestinal epithelium was observed by electron microscopy, and gut microbiota in rat feces were analyzed using 16S rDNA high-throughput sequencing. ResultsCompared with the normal group, the sucrose preference of rats in the model group was significantly reduced (P<0.01), whereas it was significantly increased in the Sini San group compared with the model group (P<0.05). Compared with the normal group, hippocampal GABA protein levels and BDNF mRNA expression in the model group were significantly decreased (P<0.05), and compared with the model group, both were significantly increased in the Sini San group (P<0.05, P<0.01). Compared with the normal group, serum LPS and Zonulin levels in the model group were significantly increased (P<0.05, P<0.01), and compared with the model group, Zonulin levels in the Sini San group were significantly decreased (P<0.05). No obvious changes were observed in the ultrastructure of the jejunal mucosa among groups. Compared with the normal group, widened and blurred tight junctions, sparse and shortened microvilli, and mitochondrial swelling with cristae disruption in epithelial cells were observed in the ileal and colonic mucosa of the model group, which were markedly improved in the Sini San and fluoxetine groups. The results of 16S rDNA high-throughput sequencing showed that Sini San improved CUMS-induced dysbiosis of Bacteroidetes and Proteobacteria. Correlation analysis indicated that Bacteroidetes and Proteobacteria were significantly correlated with depression-related indicators, liver function, and intestinal mucosal permeability. ConclusionSini San exerts antidepressant and hepatoprotective effects by improving Bacteroidetes and Proteobacteria and inhibiting the increase in intestinal mucosal permeability in CUMS rats.
3.Effect of Yangjing Tongluo Prescription on Oxidative Damage of Endometrium in Rats with Intrauterine Adhesion Based on Keap1/Nrf2/HO-1 Signaling Pathway
Jiaying CHEN ; Jing ZENG ; Zhaoling YOU ; Yonglian WANG ; Muya LIU ; Fang ZHOU ; Li TANG ; Sainan TIAN
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(4):100-108
ObjectiveTo explore the mechanisms of Yangjing Tongluo prescription (YJTL) in the treatment of intrauterine adhesion (IUA) from the perspective of oxidative stress mediated by the Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Keap1/Nrf2/HO-1) signaling pathway. MethodsA total of 48 rats with normal estrous cycles were selected and randomly divided into a normal group (n=8) and a modeling group (n=40). An IUA rat model was established using a dual-injury method combining surgical curettage and infection. Eight rats were randomly selected from the modeling group for a pilot experiment to confirm successful model establishment. After successful modeling, the remaining 32 rats were randomly divided into a model group, a low-dose YJTL group (YJTL-L), a high-dose YJTL group (YJTL-H), and a Progynova group. Rats in the normal and model groups were administered purified water (15 mL·kg-1) by gavage daily, while rats in the YJTL-L, YJTL-H, and Progynova groups received YJTL at doses of 6.43 and 12.86 g·kg-1 and Progynova at 2.06 × 10-4 g·kg-1, respectively, for 14 consecutive days. The general condition, uterine morphology, and uterine index of the rats were monitored. Histopathological changes in uterine tissue were observed using hematoxylin-eosin (HE) staining. Serum levels of reactive oxygen species (ROS) and glutathione peroxidase (GSH-Px) were measured by enzyme-linked immunosorbent assay (ELISA). Protein expression levels of Keap1, Nrf2, and HO-1 in endometrial tissue were detected by Western blot. Immunofluorescence (IF) was used to assess the distribution of Nrf2 and HO-1, as well as the expression of Nrf2 in the cytoplasm and nucleus. ResultsCompared with the normal group, rats in the model group exhibited poor mental status and reduced mobility, markedly edematous and tortuous uterine morphology, decreased gland number, and inflammatory reactions in the endometrium, along with an increased uterine organ index (P<0.05). Serum ROS levels were significantly increased (P<0.05), while serum GSH-Px levels were significantly decreased (P<0.05). In endometrial tissue, Keap1 protein expression was increased (P<0.05), whereas Nrf2 and HO-1 protein expression was decreased. Mild nuclear translocation of Nrf2 was observed, accompanied by increased relative fluorescence intensity of nuclear Nrf2 and decreased relative fluorescence intensity of cytoplasmic HO-1. Compared with the model group, all treatment groups showed varying degrees of improvement in the above symptoms and pathological changes. Serum ROS levels were reduced (P<0.05), serum GSH-Px levels were increased (P<0.05), Keap1 protein expression in endometrial tissue was decreased, and Nrf2 and HO-1 protein expression was increased in a dose-dependent manner (P<0.05). Notably, significant nuclear translocation of Nrf2 was observed, with correspondingly increased relative fluorescence intensity of nuclear Nrf2 and enhanced relative fluorescence intensity of cytoplasmic HO-1. ConclusionYJTL may enhance antioxidant capacity and repair oxidative damage to the endometrial basal layer by regulating the Keap1/Nrf2/HO-1 signaling pathway.
4.Pharmacodynamic Substances and Mechanisms of Xinglou Chengqi Tang in Treating Post-stroke Complications: A Review
Yujin ZHANG ; Xiangzhuo LIU ; Zhouyang CHEN ; Zihao SONG ; Xinyi LIU ; Yizhi YAN ; Chaoya LI ; Yingyan FANG ; Shasha YANG ; Xueqin CHENG ; Zhou XIE ; Sijie TAN ; Peng ZENG ; Yue ZHANG
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(1):327-337
Stroke is the leading cause of death and disability among adults in China, and its common complications include digestive system abnormalities, cognitive impairment, depression, stroke-associated pneumonia, and hemiplegia. The combination of traditional Chinese and Western medicine has great potential in treating post-stroke complications. Xinglou Chengqitang (XLCQT) is a representative prescription of alleviating the disease in the upper part by treating the lower part. It has definite therapeutic effect and high safety. Clinically, XLCQT is often used to treat stroke and its complications. However, the quantity and quality of clinical trials of XLCQT in treating post-stroke complications need to be improved. Additionally, since the basic research is weak, the material basis and multi-target mechanism for the efficacy of this prescription are unknown. This article reviews XLCQT in terms of the pharmacodynamic basis, medicinal properties, safety evaluation, and progress in clinical research and mechanisms in treating post-stroke complications. This article summarizes 22 key active ingredients of XLCQT in treating acute stroke complicated with syndrome of phlegm heat and fu-organ excess. Among these key active ingredients, resveratrol, kaempferol, luteolin, chrysoeriol, apigenin, (+)-catechin, and adenosine have good pharmacokinetic properties and high bioavailability. The mechanisms of XLCQT in treating post-stroke complications are complex, including inflammatory response, brain-gut axis, hypothalamic-pituitary-adrenal (HPA) axis, intestinal flora, neurotrophic factors, autophagy, oxidative stress, and free radical damage. This review helps to deeply understand the pharmacodynamic basis and mechanisms of XLCQT in treating post-stroke complications and provides a theoretical basis for the clinical application of XLCQT against post-stroke complications and the development of drugs.
5.Visual evaluation of medical humanistic care based on the concept of implementation science
Xuancheng CHEN ; Yangyi CHEN ; Huiling LI ; Mengyun PENG ; Fanli TIAN ; Xiaojun ZHOU ; Zhisong HE ; Chen FANG
Chinese Medical Ethics 2026;39(2):194-200
ObjectiveTo introduce visual teaching into the course design of medical humanistic care based on the concept of implementation science, evaluate the teaching implementation effect and feedback, and provide references for optimizing course teaching outcomes and improving students’ humanistic care competence. MethodsA visual teaching program for medical humanistic care was designed, with key steps including clarifying teaching objectives, content, methods, and curriculum assessment. This program was implemented in the medical humanistic care course teaching involving 50 elective students. Multi-dimensional evaluation of teaching effectiveness was conducted through course grades, visual teaching evaluation, and humanistic workshop assessment, combined with inductive content analysis of students’ learning experiences in the workshops. ResultsThe 50 students achieved above-average course grades (89.60±3.41) and demonstrated high satisfaction with the overall course and visual teaching. All the 6 groups obtained relatively high scores in the medical humanistic care workshops. Four themes were extracted, namely, enhancing humanistic care competencies, deepening familial and interpersonal relationships, realizing emotional expression and self-growth, and strengthening integration of humanistic care concepts with practice. ConclusionThe teaching of medical humanistic care course has achieved favorable effects, which contributes to deepening students’ understanding of humanistic care and enhancing their humanistic care competence. Students demonstrate high levels of recognition and satisfaction with the course.
6.Preliminary application of histological evaluation of donor pancreas biopsy tissue in simultaneous pancreas-kidney transplantation
Jiao WAN ; Hui GUO ; Jiali FANG ; Guanghui LI ; Luhao LIU ; Yunyi XIONG ; Wei YIN ; Tong YANG ; Junjie MA ; Zheng CHEN
Organ Transplantation 2026;17(2):250-256
Objective To preliminarily investigate the safety and efficacy of donor pancreas needle biopsy in simultaneous pancreas-kidney transplantation. Methods Clinical data of 7 cases undergoing donor pancreas biopsy were collected retrospectively. All cases underwent donor pancreas biopsy before or during simultaneous pancreas-kidney transplantation. Frozen section or paraffin sectioning techniques were used for tissue preparation, and hematoxylin-eosin and Masson staining were performed to histologically evaluate the donor pancreas. The quality of donor pancreas was comprehensively assessed by combining histological findings with the donor's clinical data. Postoperative follow-up data of 5 simultaneous pancreas-kidney transplant recipients were collected to summarize the safety of donor pancreas biopsy and the prognosis of transplant recipients. Results The 7 pancreas donors were aged 28 to 62 years, with a body mass index ranging from 20.76 to 27.68 kg/m2. Liver ultrasound indicated fatty liver in 3 cases, while pancreatic ultrasound did not reveal any significant abnormalities. Among them, biopsy was performed on 2 donors after completion of pancreatic procurement and processing, and the frozen section histology showed moderate acute pancreatitis changes (edema of acinar cells, necrosis and inflammatory cell infiltration). Combined with a serum amylase level elevated more than 3 times the upper limit of normal value, these two donor pancreases were finally discarded. The remaining 5 cases underwent biopsy immediately after pancreatic vascular anastomosis during simultaneous pancreas-kidney transplantation, and histological evaluation was performed on paraffin-embedded sections. No biopsy-related complications (such as bleeding, pancreatic fistula, etc.) occurred after transplantation. One recipient died of severe infection 2 months after transplantation, while the other 4 recipients were followed up for more than 5 years, with well-functioning transplant kidneys and pancreases. Conclusions Donor pancreas biopsy is relatively safe, and the risk of biopsy-related complications after transplantation is controllable. Comprehensive assessment of donor pancreas quality by combining histological evaluation with the donor's clinical indicators is conducive to improving the accuracy of donor pancreas selection and organ utilization.
7.Relationship between non-suicidal self-injury behaviors, impulsivity, and emotional regulation in adolescents with depressive disorder
Mingfei ZHANG ; Xinyu CHEN ; Fang LIANG ; Zhe CHEN ; Lu QIAN ; Zhijia LI
Sichuan Mental Health 2026;39(1):21-26
BackgroundAdolescents with depressive disorder often engage in non-suicidal self-injury (NSSI) behaviors, which severely impacts their physical and mental health. Impulsivity and emotional regulation are key factors influencing NSSI behaviors. However, research on the mechanisms through which impulsivity and emotional regulation affect NSSI behaviors in adolescent depressive disorder patients with NSSI remains insufficient, limiting the development of effective intervention strategies. ObjectiveTo explore the differences in impulsivity and emotion regulation abilities between adolescent patients with depressive disorder accompanied by and without NSSI behaviors, and to analyze the association between NSSI behaviors and impulsivity and emotion regulation abilities in adolescent patients with depressive disorder accompanied by NSSI behaviors. MethodsA total of 184 adolescents hospitalized in the child and adolescent psychiatry department of Wuxi Mental Health Center from October 2023 to August 2024, who met the diagnostic criteria for depressive disorder according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), were consecutively enrolled as study subjects. Based on the diagnostic criteria for NSSI in DSM-5, patients were divided into NSSI group (n=108) and non-NSSI group (n=76). The Barratt Impulsiveness Scale-11 (BIS-11), the Emotion Regulation Questionnaire (ERQ), the Adolescent Self-Harm Questionnaire, and the Positive and Negative Suicide Ideation (PANSI) were used for assessment. Spearman correlation analysis was employed to explore the correlation between the scores of the Adolescent Self-Harm Questionnaire and the scores of BIS-11 and ERQ in the NSSI group. Multiple regression analysis was conducted to examine the effects of impulsivity and emotion regulation on NSSI behaviors in the NSSI group. ResultsCompared to the non-NSSI group, the NSSI group showed significantly higher scores in BIS-11 non-planned impulsivity (Z=-4.181, P<0.05), action impulsivity (t=4.944, P<0.05), cognitive impulsivity (Z=-3.392, P<0.05), and total score (t=4.763, P<0.05), and lower scores in the cognitive reappraisal of ERQ (t=-4.094, P<0.05) and total score (Z=-2.299, P<0.05), and higher scores in the expression inhibition of ERQ (Z=-3.019, P<0.05). The correlation analysis results showed that the score of the adolescent self-harm questionnaire in the NSSI group was positively correlated with the behavioral impulsivity factor score in the BIS-11 (r=0.434, P<0.05). Multiple regression analysis indicated that action impulsivity factor was a significant correlate of self-injury behaviors in the NSSI group (B=0.855, P<0.05), explaining 22.30% of the total variance. ConclusionAdolescent patients with depressive disorder accompanied by NSSI behaviors exhibit higher levels of impulsivity and poorer emotional regulation abilities. Action impulsivity may play a significant role in the mechanism of NSSI behaviors. [Funded by Wuxi Municipal Health Commission Research Project (number, Q202320)]
8.Association among childhood obesity, type 2 diabetes mellitus and coronary artery heart disease: a Mendelian randomization study
CHEN Haimiao ; MA Yan ; LIU Mingqi ; MA Shanshan ; LI Jun ; FANG Yirong
Journal of Preventive Medicine 2025;37(3):307-311
Objective:
To investigate the association between childhood obesity and type 2 diabetes mellitus (T2DM) as well as coronary artery heart disease (CHD).
Methods:
Genome-wide association study (GWAS) data for childhood obesity were collected from the ECG consortium, encompassing information on children aged 2 to 18 years, including 18 613 cases and 12 696 controls. GWAS data for T2DM were collected from the DIAGRAM consortium, including 242 283 cases and 1 569 734 controls. GWAS data for CHD were collected from the CARDIoGRAMplusC4D consortium, including 10 801 cases and 137 371 controls. Pleiotropic genes associated with both T2DM and CHD were analyzed using the MAGMA, PLACO and conditional false discovery rate (cFDR) methods. Mendelian randomization (MR) analysis was performed using inverse variance weighted (IVW) method, exploring the causal relationships among childhood obesity, T2DM and CHD. Heterogeneity was evaluated using Cochran's Q test, horizontal pleiotropy and exclude outliers were tested using MR-Egger regression and MR-PRESSO test. The mediating variables among the three diseases were investigated by using a mediation analysis.
Results:
The results of MAGMA, PLACO and cFDR analyses identified 80 pleiotropic genes associated with both T2DM and CHD, primarily distributed on chromosomes 3, 17 and 19. The MR analysis revealed that childhood obesity increased the risk of T2DM (OR=1.151, 95%CI: 1.033-1.283) and CHD (OR=1.158, 95%CI: 1.068-1.255), T2DM increased the risk of CHD (OR=1.182, 95%CI: 1.139-1.227), and CHD increased the risk of T2DM (OR=1.124, 95%CI: 1.055-1.198). The MR-Egger regression analysis showed no horizontal pleiotropy, and the MR-PRESSO test did not identify any outliers (all P>0.05). Mediation analysis indicated that childhood obesity directly increased the risk of CHD (effect value=0.096, 95%CI: 0.012-0.180) and indirectly increased the risk of CHD through T2DM (effect value=0.023, 95%CI: 0.005-0.041), with the mediation effect accounting for 15.65% of the total effect.
Conclusions
There are potential causal associations between childhood obesity and T2DM as well as CHD, with a bidirectional causal relationship between T2DM and CHD. T2DM also plays a mediating role in the association between childhood obesity and CHD.
9.Therapeutic Study on The Inhibition of Neuroinflammation in Ischemic Stroke by Induced Regulatory T Cells
Tian-Fang KANG ; Ai-Qing MA ; Li-Qi CHEN ; Han GONG ; Jia-Cheng OUYANG ; Fan PAN ; Hong PAN ; Lin-Tao CAI
Progress in Biochemistry and Biophysics 2025;52(4):946-956
ObjectiveNeuroinflammation plays a crucial role in both the onset and progression of ischemic stroke, exerting a significant impact on the recovery of the central nervous system. Excessive neuroinflammation can lead to secondary neuronal damage, further exacerbating brain injury and impairing functional recovery. As a result, effectively modulating and reducing neuroinflammation in the brain has become a key therapeutic strategy for improving outcomes in ischemic stroke patients. Among various approaches, targeting immune regulation to control inflammation has gained increasing attention. This study aims to investigate the role of in vitro induced regulatory T cells (Treg cells) in suppressing neuroinflammation after ischemic stroke, as well as their potential therapeutic effects. By exploring the mechanisms through which Tregs exert their immunomodulatory functions, this research is expected to provide new insights into stroke treatment strategies. MethodsNaive CD4+ T cells were isolated from mouse spleens using a negative selection method to ensure high purity, and then they were induced in vitro to differentiate into Treg cells by adding specific cytokines. The anti-inflammatory effects and therapeutic potential of Treg cells transplantation in a mouse model of ischemic stroke was evaluated. In the middle cerebral artery occlusion (MCAO) model, after Treg cells transplantation, their ability to successfully migrate to the infarcted brain region and their impact on neuroinflammation levels were examined. To further investigate the role of Treg cells in stroke recovery, the changes in cytokine expression and their effects on immune cell interactions was analyzed. Additionally, infarct size and behavioral scores were measured to assess the neuroprotective effects of Treg cells. By integrating multiple indicators, the comprehensive evaluation of potential benefits of Treg cells in the treatment of ischemic stroke was performed. ResultsTreg cells significantly regulated the expression levels of both pro-inflammatory and anti-inflammatory cytokines in vitro and in vivo, effectively balancing the immune response and suppressing excessive inflammation. Additionally, Treg cells inhibited the activation and activity of inflammatory cells, thereby reducing neuroinflammation. In the MCAO mouse model, Treg cells were observed to accumulate in the infarcted brain region, where they significantly reduced the infarct size, demonstrating their neuroprotective effects. Furthermore, Treg cell therapy notably improved behavioral scores, suggesting its role in promoting functional recovery, and increased the survival rate of ischemic stroke mice, highlighting its potential as a promising therapeutic strategy for stroke treatment. ConclusionIn vitro induced Treg cells can effectively suppress neuroinflammation caused by ischemic stroke, demonstrating promising clinical application potential. By regulating the balance between pro-inflammatory and anti-inflammatory cytokines, Treg cells can inhibit immune responses in the nervous system, thereby reducing neuronal damage. Additionally, they can modulate the immune microenvironment, suppress the activation of inflammatory cells, and promote tissue repair. The therapeutic effects of Treg cells also include enhancing post-stroke recovery, improving behavioral outcomes, and increasing the survival rate of ischemic stroke mice. With their ability to suppress neuroinflammation, Treg cell therapy provides a novel and effective strategy for the treatment of ischemic stroke, offering broad application prospects in clinical immunotherapy and regenerative medicine.
10.Structural and Spatial Analysis of The Recognition Relationship Between Influenza A Virus Neuraminidase Antigenic Epitopes and Antibodies
Zheng ZHU ; Zheng-Shan CHEN ; Guan-Ying ZHANG ; Ting FANG ; Pu FAN ; Lei BI ; Yue CUI ; Ze-Ya LI ; Chun-Yi SU ; Xiang-Yang CHI ; Chang-Ming YU
Progress in Biochemistry and Biophysics 2025;52(4):957-969
ObjectiveThis study leverages structural data from antigen-antibody complexes of the influenza A virus neuraminidase (NA) protein to investigate the spatial recognition relationship between the antigenic epitopes and antibody paratopes. MethodsStructural data on NA protein antigen-antibody complexes were comprehensively collected from the SAbDab database, and processed to obtain the amino acid sequences and spatial distribution information on antigenic epitopes and corresponding antibody paratopes. Statistical analysis was conducted on the antibody sequences, frequency of use of genes, amino acid preferences, and the lengths of complementarity determining regions (CDR). Epitope hotspots for antibody binding were analyzed, and the spatial structural similarity of antibody paratopes was calculated and subjected to clustering, which allowed for a comprehensively exploration of the spatial recognition relationship between antigenic epitopes and antibodies. The specificity of antibodies targeting different antigenic epitope clusters was further validated through bio-layer interferometry (BLI) experiments. ResultsThe collected data revealed that the antigen-antibody complex structure data of influenza A virus NA protein in SAbDab database were mainly from H3N2, H7N9 and H1N1 subtypes. The hotspot regions of antigen epitopes were primarily located around the catalytic active site. The antibodies used for structural analysis were primarily derived from human and murine sources. Among murine antibodies, the most frequently used V-J gene combination was IGHV1-12*01/IGHJ2*01, while for human antibodies, the most common combination was IGHV1-69*01/IGHJ6*01. There were significant differences in the lengths and usage preferences of heavy chain CDR amino acids between antibodies that bind within the catalytic active site and those that bind to regions outside the catalytic active site. The results revealed that structurally similar antibodies could recognize the same epitopes, indicating a specific spatial recognition between antibody and antigen epitopes. Structural overlap in the binding regions was observed for antibodies with similar paratope structures, and the competitive binding of these antibodies to the epitope was confirmed through BLI experiments. ConclusionThe antigen epitopes of NA protein mainly ditributed around the catalytic active site and its surrounding loops. Spatial complementarity and electrostatic interactions play crucial roles in the recognition and binding of antibodies to antigenic epitopes in the catalytic region. There existed a spatial recognition relationship between antigens and antibodies that was independent of the uniqueness of antibody sequences, which means that antibodies with different sequences could potentially form similar local spatial structures and recognize the same epitopes.


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