ObjectiveTo investigate the migration and distribution characteristics of chemical constituents in blood and hippocampal tissues before and after vinegar processing of Citri Reticulatae Pericarpium Viride（CRPV）， and to explore the potential material basis and mechanisms underlying their regulatory effects on emotional disorders by comparing the effects of raw and vinegar-processed products of CRPV. MethodsUltra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry（UPLC-Q-TOF-MS/MS） was employed to characterize and identify the chemical constituents of raw and vinegar-processed products of CRPV extracts， as well as their migrating components in blood and hippocampal tissues after oral administration. Reference standards， databases， and relevant literature were utilized for compound annotation， with data processing performed using PeakView 1.2 software. Seventy male C57BL/6 mice were randomly divided into seven groups， including the blank group， model group， diazepam group（2.5 mg·kg^-1）， raw CRPV low/high dose groups（0.6， 1.2 g·kg^-1）， and vinegar-processed CRPV low/high dose groups（0.6， 1.2 g·kg^-1）， with 10 mice per group. Except for the blank group， all other groups underwent chronic restraint stress（2 h·d^-1） for 20 d. Each drug-treated group received oral administration at the predetermined dose starting 10 d after modeling， with a total treatment duration of 10 d. Following model-based drug administration， mice underwent open-field， forced swimming， and elevated plus maze tests. After anesthesia with isoflurane， whole brains were collected from each group of mice， and hippocampi were dissected. Reactive oxygen species（ROS） level in hippocampal tissues was quantified by enzyme-linked immunosorbent assay（ELISA）. Hematoxylin-eosin（HE） staining was used to observe hippocampal tissue morphology. Immunofluorescence was performed to detect neuronal nuclei（NeuN） and peroxisome proliferator-activated receptor alpha（PPARα） expressions in hippocampal tissue. Then， pharmacodynamic evaluations were conducted to assess the effects of raw and vinegar-processed CRPV on mood disorders， exploring the potential mechanisms. ResultsVinegar processing caused significant changes in the chemical composition of CRPV， with 18 components showing increased relative content and 35 components showing decreased relative content. The primary changes occurred in flavonoid compounds， including 20 flavonoids， 20 flavonoid glycosides， 3 triterpenes， 3 phenolic acids， 1 alkaloid， and 6 other compounds. Twenty-one components were detected in blood（15 methoxyflavones， 4 flavonoid glycosides， and 2 phenolic acids）， with 17 shared between raw and vinegar-processed CRPV. Seven components reached hippocampal tissues（all common to both forms）. In regulating emotional disorders， Vinegar-processed CRPV exhibited superior antidepressant-like effects compared to raw products. HE staining revealed that both treatments improved hippocampal neuronal morphology， particularly in the damaged CA1 and CA3 regions. Immunofluorescence and ELISA analyses demonstrated that both raw and vinegar-processed CRPV significantly modulated NeuN and PPARα expressions in hippocampal tissue while alleviating oxidative stress induced by excessive ROS（P<0.05）. ConclusionThe chemical composition of CRPV undergoes changes after vinegar processing， but the migrating components in blood and hippocampus are primarily methoxyflavonoids. These components may serve as the potential material basis for activating the PPARα pathway， thereby negatively regulating ROS generation in the hippocampus， reducing oxidative stress， and promoting the development of NeuN-positive neurons. These findings provide experimental evidence for enhancing quality standards， pharmacodynamic material research， and active drug development of raw and vinegar-processed CRPV.

Oral squamous cell carcinoma (OSCC) is a common head and neck malignancy. Approximately 50% to 60% of patients with OSCC are diagnosed at a locally advanced stage (clinical staging III-IVa). Even with comprehensive and sequential treatment primarily based on surgery, the 5-year overall survival rate remains below 50%, and patients often suffer from postoperative functional impairments such as difficulties with speaking and swallowing. Programmed death receptor-1 (PD-1) inhibitors are increasingly used in the neoadjuvant treatment of locally advanced OSCC and have shown encouraging efficacy. However, clinical practice still faces key challenges, including the definition of indications, optimization of combination regimens, and standards for efficacy evaluation. Based on the latest research advances worldwide and the clinical experience of the expert group, this expert consensus systematically evaluates the application of PD-1 inhibitors in the neoadjuvant treatment of locally advanced OSCC, covering combination strategies, treatment cycles and surgical timing, efficacy assessment, use of biomarkers, management of special populations and immune related adverse events, principles for immunotherapy rechallenge, and function preservation strategies. After multiple rounds of panel discussion and through anonymous voting using the Delphi method, the following consensus statements have been formulated: 1) Neoadjuvant therapy with PD-1 inhibitors can be used preoperatively in patients with locally advanced OSCC. The preferred regimen is a PD-1 inhibitor combined with platinum based chemotherapy, administered for 2-3 cycles. 2) During the efficacy evaluation of neoadjuvant therapy, radiographic assessment should follow the dual criteria of Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 and immune RECIST (iRECIST). After surgery, systematic pathological evaluation of both the primary lesion and regional lymph nodes is required. For combination chemotherapy regimens, PD-L1 expression and combined positive score need not be used as mandatory inclusion or exclusion criteria. 3) For special populations such as the elderly (≥ 70 years), individuals with stable HIV viral load, and carriers of chronic HBV/HCV, PD-1 inhibitors may be used cautiously under the guidance of a multidisciplinary team (MDT), with close monitoring for adverse events. 4) For patients with a poor response to neoadjuvant therapy, continuation of the original treatment regimen is not recommended; the subsequent treatment plan should be adjusted promptly after MDT assessment. Organ transplant recipients and patients with active autoimmune diseases are not recommended to receive neoadjuvant PD-1 inhibitor therapy due to the high risk of immune related activation. Rechallenge is generally not advised for patients who have experienced high risk immune related adverse events such as immune mediated myocarditis, neurotoxicity, or pneumonitis. 5) For patients with a good pathological response, individualized de escalation surgery and function preservation strategies can be explored. This consensus aims to promote the standardized, safe, and precise application of neoadjuvant PD-1 inhibitor strategies in the management of locally advanced OSCC patients.

ObjectiveTo explore the therapeutic mechanism of Buchong Tiaojing prescription for rats with diminished ovarian reserve （DOR） from the perspectives of nucleotide-binding oligomerization domain （NOD）-like receptor protein 3 （NLRP3） inflammasome and ferroptosis. MethodsA total of 48 female SD rats were randomly divided into a normal group， a model group， low， medium， and high dose groups of Buchong Tiaojing prescription， and an MCC950 group， with eight rats in each group. Except the normal group， all the other groups were injected subcutaneously on the back of the neck with D-galactose to prepare the DOR rat model. From the 15th day of modeling， the rats in the low， medium， and high dose groups of Buchong Tiaojing prescription were subjected to gavage daily at doses of 14.4， 28.8， 57.6 g·kg^-1， respectively. Rats in the MCC950 group were injected intraperitoneally with MCC950 at a dose of 10 mg·kg^-1， once every other day. The interventions of all the groups lasted for 4 weeks. The estrous cycle of the rats was observed with vaginal exfoliated cell smear. Hematoxylin-eosin （HE） staining was performed to observe the development of follicles and corpus luteum in the ovary. Enzyme-linked immunosorbent assay （ELISA） was performed to detect the levels of serum sex hormones and interleukin-1β （IL-1β）. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot assay were performed to detect the mRNA and protein expression of NLRP3 inflammasome， acyl-CoA synthetase long-chain family member 4 （ACSL4）， transferrin receptor 1 （TFR1）， and glutathione peroxidase 4 （GPX4）， and oxidative stress kits were used to detect ovarian superoxide dismutase （SOD） and malondialdehyde （MDA） levels. ResultsDuring the experiment， one rat died in the high dose group of Buchong Tiaojing prescription， and a total of 47 rats were finally included in the index tests and statistics. Compared with those in the normal group， rats in the model group had significantly disturbed estrous cycles， increased number of atretic follicles， and significant disorder of serum sex hormones. The mRNA and protein expression of NLRP3 inflammasome， ACSL4， and TFR1 in ovarian tissue was up-regulated （P<0.01）， while that of GPX4 was significantly down-regulated （P<0.01）. The SOD content in the ovary was decreased significantly， while the MDA level was increased （P<0.01）. After drug intervention， the estrous cycle of rats was basically resumed， and the follicles at all levels were more structurally intact and significantly increased in number. Additionally， the levels of serum sex hormones and IL-1β were significantly improved. The mRNA and protein expression of NLRP3 inflammasome， ACSL4， and TFR1 were down-regulated， while that of GPX4 was significantly up-regulated， and the ovarian oxidative stress was alleviated （P<0.05， P<0.01）， especially in the high dose group of Buchong Tiaojing prescription and the MCC950 group. ConclusionInflammatory injury and ferroptosis occur in the ovaries of DOR rats， and the Buchong Tiaojing prescription is able to inhibit ovarian NLRP3 inflammasome， alleviate the degree of ovarian ferroptosis， and improve ovarian reserve.

[Objective] To analyze the loss rate of platelet donors and evaluate the strategies for establishing a platelet donor bank. [Methods] A total of 1 443 donors who joined the HLA and HPA gene donor bank for platelets in Henan Province from 2018 to 2020 were included in this study. Data on the total number of apheresis platelet donations, annual donation frequency, age at enrollment, donation habits (including the number of platelets donated per session and whether they had previously donated whole blood), and enrollment location were collected from the platelet donor information management system. Donor loss was determined based on the date of their last donation. The loss rates of different groups under various conditions were compared to assess the enrollment strategies. [Results] By the time the platelet bank was officially operational in 2022, 421 donors had been lost, resulting in an loss rate of 29% (421/1 443). By the end of 2023, the overall cumulative loss rate reached 52% (746/1 443). The loss rate was lower than the overall level in groups meeting any of the following conditions: total apheresis platelet donations exceeding 50, annual donation frequency of 10 or more, age at enrollment of 40 years or older, donation of more than a single therapeutic dose per session, or a history of whole blood donation two or more times. Additionally, loss rates varied across different enrollment locations, with higher enrollment numbers generally associated with higher loss rates. [Conclusion] Through a comprehensive analysis of donor loss, our center has adjusted its strategies for establishing the donor pool. These findings also provide valuable insights for other blood collection and supply institutions in building platelet donor banks.

ObjectiveTo screen and evaluate the antidepressant compounds of Curcumae Rhizoma， and explore its mechanism of regulating the nuclear factor erythroid 2-related factor 2（Nrf2）/glutathione（GSH） peroxidase 4（GPX4）/GSH pathway from an antioxidant perspective. MethodsThe antioxidant activities in vitro of 11 characteristic components from Curcumae Rhizoma， including curcumol， curgerenone， curdione， curzerene， curcumenol， curcumenone， dehydrocurdione， isocurcumenol， furanodienone， furanodiene and zederone， were detected using 1，1-diphenyl-2-picrylhydrazyl（DPPH） and 2，2'-azinobis-（3-ethylbenzothiazoline-6-sulphonic acid） diammonium salt（ABTS） radical scavenging assays. The depression in Drosophila melanogaster was induced by chronic unpredictable mild stress（CUMS）， and W1118 wild-type male D. melanogaster were randomly divided into blank group， model group， curcumol group， curgerenone group， curdione group， curzerene group， curcumenol group，curcumenone group， dehydrocurdione group， isocurcumenol group， furanodienone group， furanodiene group， zederone group and fluoxetine group（10 μmol·L^-1）. The treatment groups received a dose of 0.1 g·L^-1 of 11 characteristic components from Curcumae Rhizoma， while the blank and model groups were administered equivalent volumes of solvent. The sucrose preference test， climbing test and forced swimming test were used to evaluate the behavioral indicators of depression in D. melanogaster. Liquid chromatography-mass spectrometry（LC-MS） was used to detect the levels of 5-hydroxytryptamine（5-HT） and dopamine（DA） in the brain of D. melanogaster， and the entropy weight method was used to comprehensively evaluate neurobehavioral and neurotransmitter indicators， resulting in the identification of the antidepressant active components of Curcumae Rhizoma. In addition， a mouse depression model was established by CUMS， and C57BL/6J mice were randomly divided into blank group， model group， low and high dose groups of curzerene（0.5， 1 mg·kg^-1）， and fluoxetine group（10 mg·kg^-1） to confirm the antidepressant effect of the optimal active ingredient by behavioral analysis. Flow cytometry was used to detect the content of reactive oxygen species（ROS） in the hippocampus of mice from each group. Enzyme-linked immunosorbent assay was used to detect the contents of adenosine triphosphate（ATP）， superoxide dismutase（SOD）， catalase（CAT） and GSH. Transmission electron microscope（TEM） was used to observe the effect of curzerene on the ultrastructure of mitochondria in hippocampal tissue. Western blot was performed to determine the level of Nrf2 protein， and Nrf2 inhibitor（ML385） was used to verify the relationship between the antidepressant effect of curzerene and regulation of Nrf2. Real time fluorescence quantitative polymerase chain reaction（Real-time PCR） was employed to detect the effect of curzerene on the mRNA expression level of GPX. ResultsIn vitro antioxidant experiments showed that curzerene and curgerenone exhibited the most significant ability to scavenge free radicals， and comprehensive evaluation results of entropy weight method indicated that curzerene stood out as the most promising active component. Compared with the blank group， the model group exhibited a significant decrease in sucrose preference coefficient and the number of times entering the open field center（P<0.01）， as well as a significant increase in immobility time in the forced swimming and tail suspension tests（P<0.01）， and the ROS content in hippocampus significantly elevated（P<0.01）， while the ATP content significantly reduced（P<0.01）. In the hippocampal neurons of the model group， mitochondrial cristae were disordered， with vacuolation of the inner membrane and severe damage. Nrf2 protein expression level in the model group was significantly decreased（P<0.05）， and the antioxidant enzymes SOD， CAT and GSH contents were also significantly reduced（P<0.05， P<0.01）， and the gene expression levels of GPX1， GPX4 and GPX7 were significantly decreased（P<0.01）. Compared with the model group， the high-dose group of curzerene showed a significant increase in the sucrose preference coefficient and the number of times entering the open field center（P<0.05）， as well as a significant decrease in immobility time in the forced swimming and tail suspension tests（P<0.05， P<0.01）. The ROS content in the hippocampus of the high-dose group of curzerene was significantly reduced（P<0.01）， while the ATP content was significantly increased（P<0.05）. The neuronal mitochondrial damage in the hippocampus of the high-dose group of curzerene was alleviated， and the expression level of Nrf2 protein was significantly increased（P<0.05）. The Nrf2 inhibitor ML385 reversed the improvement of curzerene on depressive behaviors in CUMS mice. The GSH content in the hippocampal neurons of the high-dose group of curzerene was significantly increased（P<0.01）， while there were no significant differences in SOD and CAT contents. The expression level of GPX4 gene in the hippocampal neurons of the high-dose group of curzerene was significantly increased（P<0.05）， while there were no significant differences in other GPX genes. ConclusionCurzerene is the best component with antidepressant activity in Curcumae Rhizoma. It may improve mitochondrial dysfunction to exert its antidepressant effect by regulating Nrf2 and its downstream GPX4/GSH pathway rather than CAT or SOD pathways.

Lung transplantation is the optimal treatment for end-stage lung diseases and can significantly improve prognosis of the patients. However, postoperative complications such as infection, rejection, ischemia-reperfusion injury, and other challenges (like shortage of donor lungs) , limit the practical application of lung transplantation in clinical practice. Chinese research teams have been making continuous efforts and have achieved breakthroughs in basic research on lung transplantation by integrating emerging technologies and cutting-edge achievements from interdisciplinary fields, which has strongly propelled the development of this field. This article will comprehensively review the academic progress made by Chinese research teams in the field of lung transplantation in 2024, with a focus on the achievements of Chinese teams in basic research on lung transplantation. It aims to provide innovative ideas and strategies for key issues in the basic field of lung transplantation and to help China's lung transplantation cause reach a higher level.

BACKGROUND:Acute myocardial infarction can cause cardiac remodeling and heart failure,as well as skeletal myopathy,affecting patients'quality of life.Exercise therapy is an important rehabilitation method for patients with heart failure;however,the optimal exercise prescription has not been clarified. OBJECTIVE:To compare the effects of different exercise modes(aerobic exercise,resistance exercise)on skeletal muscle remodeling in rats with acute myocardial infarction induced heart failure and to explore the possible mechanism,so as to provide a basis for optimizing the exercise rehabilitation program. METHODS:Forty-eight Sprague-Dawley rats were randomly divided into sham operation group,myocardial infarction group,aerobic exercise group and resistance exercise group.Coronary artery ligation was used to create model of heart failure.After 3 months,animals in the aerobic exercise group and resistance exercise group underwent 12 weeks of corresponding exercise mode interventions,while those in the sham operation group and myocardial infarction group were kept quietly in mouse cages.After the experiment,maximal running speed and maximal weight-bearing load were measured by graded treadmill exercise test and ladder-climbing test respectively,and heart structure and function were evaluated by echocardiography.The heart was isolated,and hematoxylin-eosin staining and Sirius red staining were performed to detect cardiac remodeling.For the gstrocnemius muscle,ATPase staining was performed to observe changes in muscle fiber type and cell cross-sectional area,dihydroethidium method was used to evaluate reactive oxygen species levels,enzyme-linked immunosorbent method was used to determine malondialdehyde content and antioxidant enzyme activity,western blot was used to determine the expression of ubiquitin-proteasome system proteins,and the number of activated satellite cells(Pax7+/MyoD+)were detected by double immunofluorescence staining. RESULTS AND CONCLUSION:(1)Exercise performance:Compared with the sham operation group,maximal running speed and maximal weight-bearing load in the myocardial infarction group decreased(P<0.05);compared with the myocardial infarction group,the maximal running speed of the aerobic exercise group and the maximal weight-bearing load of the resistance exercise group increased(P<0.05).(2)Cardiac remodeling:Compared with the sham operation group,infarction area,myocardial cell cross-sectional area,and collagen content in the myocardial infarction group increased(P<0.05),while leftventricular ejection fraction and shortening fraction decreased(P<0.05);compared with the myocardial infarction group,there was no statistical difference in the above parameters in both aerobic exercise resistance exercise groups(P>0.05).(3)Skeletal muscle remodeling:Compared with the sham operation group,gastrocnemius muscle mass,gastrocnemius muscle mass index,cell cross-sectional area,superoxide dismutase activity,glutathione peroxidase activity,and the number of activated satellite cells decreased in myocardial infarction group(P<0.05),while reactive oxygen species content,malondialdehyde content,and the protein expression of ubiquitin,MuRF1 and MAFbx increased(P<0.05);compared with the myocardial infarction group,gastrocnemius muscle mass index,superoxide dismutase activity,the number of activated satellite cells increased in both aerobic exercise and resistance exercise groups(P<0.05),while reactive oxygen species content and the protein expression of ubiquitin,MuRF1,and MAFbx decreased(P<0.05);compared with the aerobic exercise group,gastrocnemius muscle mass,gastrocnemius muscle mass index,cell cross-sectional area,reactive oxygen species content,malondialdehyde content,the number of activated satellite cells increased in resistance exercise group(P<0.05),while superoxide dismutase activity,glutathione peroxidase activity down-regulated(P<0.05).To conclude,aerobic exercise and resistance exercise can both improve exercise performance of rats with heart failure,and the mechanism is related to reducing oxidative stress,inhibiting ubiquitin-proteasome system activity and activating satellite cells to improve skeletal muscle remodeling.Aerobic exercise has a better effect on improving skeletal muscle oxidative stress,while resistance exercise has a more significant effect on promoting skeletal muscle regeneration.

BACKGROUND:Adult stem cell therapy is one of the research hotspots in the field of peripheral nerve injury repair and regeneration.With excellent properties of mesenchymal stem cells such as high acquisition rate,wide source,and rapid proliferation,mesoderm have been regarded as the ideal source of adult stem cells,while ectoderm-derived adult stem cells,especially neural crest stem cells,have certain neurogenic properties and attract more and more attention from researchers. OBJECTIVE:To mainly review the role and mechanism of multifunctional adult stem cells from ectoderm and mesoderm in peripheral nerve injury repair and regeneration,so as to explore the research progress and application prospect of adult stem cells from different sources and discuss the potential application value of adult stem cell therapy and the problems to be solved in connection with clinical studies. METHODS:The first author searched the relevant articles published from December 2001 to February 2024 in PubMed and SinoMed by computer in February 2024.The Chinese and English search terms were"ectodermal stem cells,mesenchymal stem cells,peripheral nerve injury,repair,regeneration."Finally,69 articles were included and analyzed. RESULTS AND CONCLUSION:(1)Ectodermal adult stem cells have excellent differentiation and regeneration potential,especially epidermal neural crest stems cells,olfactory stem cells,and dental ectomesenchymal stem cells,which have certain neurogenic properties and can express neural specific markers in vitro.However,relevant clinical research needs to be accumulated.(2)There are many types of adult stem cells derived from mesoderm,which are easy to obtain and purify.Among them,the efficacy and safety of bone marrow mesenchymal stem cells and umbilical cord mesenchymal stem cells in the repair of peripheral nerve injury are supported by clinical trials;that is,they can improve sensory and motor nerve conduction and there are no complications and obvious adverse reactions in follow-up.The acquisition of bone marrow mesenchymal stem cells needs invasive surgery and requires the patient to match the donor bone marrow type,which limit the application to some extent.Although umbilical cord mesenchymal stem cells do not require invasive harvesting,their isolation is difficult and phenotypically unstable.(3)Adult stem cells derived from endoderm often fail to grow in vitro,so the possibility of clinical application is low.(4)In conclusion,bone marrow mesenchymal stem cells are still the first choice for adult stem cell therapy in the treatment of peripheral nerve injury,which is suitable for cases without surgical contraindications and meeting the matching requirements,followed by umbilical cord mesenchymal stem cells supplemented by improved isolation methods and advanced phenotypic stability strategies.(5)Dental ectomesenchymal stem cells and adipose-derived mesenchymal stem cells have high application potential and need to be further tested in clinical trials.Other adult stem cells derived from ectodermal and mesodermal layers have significant advantages in animal and cell experimental studies due to their excellent properties.

Pancreatic cancer is a kind of highly malignant tumor with a low survival rate and poor prognosis. The effectiveness of gemcitabine as a first-line chemotherapy drug is limited; however, it can activate dendritic cells and improve antigen presentation which increase the sensitivity of tumor cell to immunotherapy. Although immunotherapy has made some advancements in cancer treatment, the therapeutic benefit of programmed cell death receptor 1/programmed death receptor-ligand 1 (PD-1/PD-L1) blockade therapy remains relatively low. The chemokine C-X-C chemokine ligand 12 (CXCL12) contributes to an immunosuppressive tumor microenvironment by recruiting immunosuppressive cells. The receptor C-X-C motif chemokine receptor 4 (CXCR4), highly expressed in various tumors including pancreatic cancer, plays a crucial role in tumor development and progression. In this study, the anti-tumor immune response of human peripheral blood mononuclear cell (hPBMC) was enhanced using the combination of BsNb PX4 (anti-PD-L1&CXCR4 bispecific nanobody) and gemcitabine. In a co-culture system of gemcitabine-pretreated hPBMCs with tumor cells, the BsNb PX4 synergized gemcitabine to improve the cytotoxic activity of hPBMCs against tumor cells. Flow cytometry analysis confirmed increased ratio of CD8⁺ to CD4⁺ T cells in combination treatment. In NOD/SCID mice bearing pancreatic cancer, the combination treatment exhibited more infiltration of CD8⁺ T cells into tumor tissues, contributing to an effective anti-tumor response. This study presents potential new therapies for the treatment of pancreatic cancer. Ethical approval was obtained for collection of hPBMC samples from the Local Ethics Committee of Shanghai Jiao Tong University. All animal experiments were approved by the Animal Ethic Committee of Shanghai Jiao Tong University (authorizing number: A2024246).

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.