Objective To explore the effect and preliminary mechanism of the plant-derived immunostimulatory molecule,ophiopogonin,on enhancing the immune response of a subunit vaccine with the receptor-binding domain(RBD)of coronavirus spike protein as the antigen.Methods CCK-8 assay was used to determine the cytotoxicity of ophiopogonin D'(OPD')on bone marrow-derived dendritic cells(BMDCs).Female Balb/c mice were randomly divided into RBD,RBD/OPD',RBD/Alum,and control groups.The immunization dose was 5 μg of antigen per mouse and 100 μg of adjuvant per mouse,and immunization was carried out according to the intramuscular injection immunization procedure on days 0,21,and 42.The titers of specific IgG and its subtype antibodies were detected by ELISA.The cytokine levels in the supernatant of splenocytes were detected using ELISA.The number of splenocytes secreting IFN-γ was detected by ELISpot.Laser confocal microscopy was employed to observe the uptake of antigen by BMDCs.The phagocytic ability of BMDCs for antigen was quantitatively analyzed by flow cytometry.The mechanism of its enhanced immune effect was preliminarily explored using transcriptomics technology combined with bioinformatics research.Results When the concentration of OPD'was less than 5 μg/mL,the survival rate of BMDCs was 100%.After a single intramuscular injection in mice,except for a slight decrease in body weight,the other biochemical indicators were within corresponding normal ranges.After intramuscular injection immunization of the vaccine,the titers of serum-specific IgG,IgG1,and IgG2a in the RBD/OPD'group were significantly higher than those in the RBD group(P<0.05).Compared with the RBD group,the RBD/OPD'group induced a high-level Th1 cell immune response of IL-1β,TNF-α,and IFN-γ(P<0.01)and had more lymphocytes secreting IFN-γ(P<0.001).Laser confocal microscopy displayed that BMDCs took up more antigens after OPD'treatment,which was further confirmed with flow cytometry in quantitative analysis on antigen uptake rate(P<0.01).Transcriptomics results indicated that there was more significant enrichment of the PPAR signaling pathway in the RBD/OPD'group than the RBD group,suggesting that OPD'may activate the PPAR signaling pathway to exert its adjuvant effect.Conclusion OPD'effectively enhances the immune response of the RBD subunit vaccine,and its action mechanism may be related to the activation of the PPAR signaling pathway.

Objective To construct an in vitro co-culture model of gastric cancer organoids and cancer-associated fibroblasts(CAFs),and investigate the role of cancer-associated fibroblasts in the proliferation and chemotherapy resistance of gastric cancer organoids.Methods Tumor tissues from 12 gastric cancer patients undergoing surgical treatment in Department of General Surgery of Second Affiliated Hospital of Army Medical University from February 2023 to March 2024 were collected to construct gastric cancer organoids using 3D culture.HE staining was used to observe the morphology,and immunohistochemical assay was employed to determine the expression of cytokeratin CK7,carcinoembryonic antigen(CEA),and proliferation marker Ki-67.After CAFs derived from the same patient were cultured,observed for their morphology under a light microscope,and detected for the phenotype by flow cytometry,the cells were co-cultured with gastric cancer organoids in a 1:1 ratio.Phase-contrast microscopy was applied to observe the growth of the organoids and analyze the number,average diameter,and total area.Then,organoids cultured alone served as the control group.After the control and co-culture groups were treated with chemotherapy drugs,5-fluorouracil and oxaliplatin,for 48 h,the viability and apoptosis of organoids were assessed with CellTiter-Glo??3D assay and CellEvent? Caspase 3/7 activity,respectively.Results Gastric cancer organoids and CAFs were successfully established from 10 gastric cancer patient-derived samples.The gastric cancer organoids exhibited morphological characteristics consistent with the corresponding primary tumors,and showed positive expression of CK7,CEA,and Ki-67.CAFs displayed typical spindle-shaped morphology and exhibited the phenotypic markers CD326-,CD45-,CD31-,α-SMA+,CD73+,CD90+,and CD105+.Compared to the organoids cultured alone,the organoids co-cultured with CAFs showed more formation of organoids,in larger average diameter,and taking larger total area(P<0.05).After the treatment of 5-fluorouracil and oxaliplatin,the half-maximal inhibitory concentration(IC50)was 10.66 and 3.26 μmol/L,respectively in the control group,while was 46.23 and 91.11 μmol/L in the co-culture group.Additionally,the number of CellEvent? Caspase 3/7 positive apoptotic cells was significantly less in the co-culture group than the control group.Conclusion Compared with individually cultured gastric cancer organoids,the co-culture model of gastric cancer organoids and CAFs better simulates the pro-tumor proliferation and drug resistance effects of in vivo tumor microenvironment.

Objective To establish a mouse model of infection with the minimum lethal dose of Vibrio vulnificus(V.vulnificus)and to evaluate the protective efficacy of inactivated whole-cell(IWC)vaccine using this model.Methods A mouse model of lethal-dose infection was established by intraperitoneal injection of different doses of V.vulnificus.Bacterial colonization in the organs was detected with tissue homogenate plating,and pathological changes in the organs were observed after tissue section staining.Flow cytometry was used to detect immune cell responses after liver tissues were digested into single-cell suspension.IWC vaccine of V.vulnificus was prepared,and the mice were immunized through different routes to observe the protective efficacy of the vaccine.Results A mouse model of infection with the minimum lethal dose at 1×106 CFU of V.vulnificus was successfully established.After infection,the bacteria were mainly colonized in the liver of mice and caused severe pathological damages.Compared with the uninfected mice,the proportion of neutrophils in the liver was significantly increased in the infected mice,whereas the proportions of B cells and T cells were correspondingly decreased(P<0.05).A single intramuscular or intraperitoneal injection of the IWC vaccine could protect the mice effectively against lethal infection of V.vulnificus in 7 d later(P<0.01),although the level of serum IgG having no significant increase.Conclusion A mouse model of lethal-dose infection with V.vulnificus is successfully established,with histopathological characteristics.The IWC vaccine of V.vulnificus rapidly mediates immune protection in this model probably independent of IgG.

Objective To establish a mouse model of bronchiectasis with acute infection and evaluate the immunogenicity and protective effect of a self-assembling Pseudomonas aeruginosa(PA)nanoparticle vaccine rePO-FN based on fusion of PcrV-OprI(rePO)protein with self-assembling ferritin(Ferritin).Methods ① SPF-grade female C57BL/6 mice(aged 6～8 weeks,weighing 18～20 g)were randomly allocated into normal saline group,and low-,medium-and high-dose elastase groups(n=6).A mouse model of bronchiectasis was established via intratracheal instillation of different doses of elastase(30 μL of normal saline containing 0.65,1.30 and 2.60 IU elastase)for 3 consecutive days.At 14 and 21 d after modeling,ELISA and HE staining were performed respectively to detect the concentration of IL-6 and to observe pathological changes in lung tissue in order to confirm the modeling.② A recombinant plasmid encoding the gene of fusion protein rePO-FN was constructed and expressed in E.coli.The target protein was purified via affinity chromatography and renatured to obtain the desired protein.The physicochemical properties of the rePO-FN protein were characterized using SDS-PAGE protein gel electrophoresis,dynamic light scattering,molecular sieve chromatography,and transmission electron microscopy.③ C57BL/6J mice were randomly divided into PBS group,rePO group,rePO-FN group,and Ferritin group(n=10).The mice in the above groups were immunized intramuscularly with 100 μL PBS buffer alone or containing 10 μg of corresponding proteins on days 0,7,and 14.ELISA was used to measure the specific antibodies in serum.In 7 d after the final immunization,an acute PA infection model was used to compare the survival rates and bacterial colonization among the PBS,rePO,and rePO-FN groups.After establishing a bronchiectasis model by intratracheal instillation of 2.60 IU of elastase in C57BL/6J mice as described above,the mice were randomly divided into bronchiectasis PBS group,bronchiectasis rePO group,and bronchiectasis rePO-FN group(n=10).Immunization was conducted at the same dose and procedure as described above,in 21 d after bronchiectasis modeling.At the 7th d after the final immunization,an acute PA infection model was used to compare the survival rates and bacterial colonization among the groups.Results ①Repeated intratracheal instillation of elastase significantly increased the concentration of IL-6 in the lung tissue when compared to the content of the normal saline group(P＜0.05).Pathological observations revealed varying degrees of bronchial wall destruction,alveolar fusion,edema,neutrophil infiltration,and hemorrhage,with the severity increasing with elastase dose,which confirming successful establishment of the mouse model of bronchiectasis.② Well-dispersed rePO-FN nanoparticles were successfully prepared,with an average particle size of 91.28 nm,a Zeta potential of approximately-6.5 mV,and a polydispersity index(PDI)of 0.306.Molecular sieve chromatography determined the elution volume of rePO-FN protein to be 8.80 mL,corresponding to a molecular weight of approximately 1 400 kDa.③ Under acute PA XN-1 strain infection,the survival rate of the rePO-FN immunization group and the bronchiectasis rePO-FN immunization group were significantly higher than that of the PBS control group(P＜0.05).Additionally,bacterial colonization in the lung tissues was significantly lower in the rePO-FN immune group and the bronchiectasis rePO-FN immune group under acute PA XN-1 strain infection than that in the rePO group and the bronchiectasis rePO group(P＜0.05).Conclusion Our vaccine rePO-FN can effectively trigger a strong humoral immune response and provide significant protection against PA infection in a mouse bronchiectasis model.

In October 2024,World Health Organization(WHO)published a report titled Estimating the impact of vaccines in reducing antimicrobial resistance and antibiotic use,highlighting the role of vaccines in the global fight against antimicrobial resistance(AMR)through quantitative assessment for the first time,and calling for greater attention to the utilization and development of relevant vaccines.This article summarized and analyzed this report with the aim of providing insights for the development of superbug vaccines.

In October 2024,World Health Organization(WHO)published a report titled Estimating the impact of vaccines in reducing antimicrobial resistance and antibiotic use,highlighting the role of vaccines in the global fight against antimicrobial resistance(AMR)through quantitative assessment for the first time,and calling for greater attention to the utilization and development of relevant vaccines.This article summarized and analyzed this report with the aim of providing insights for the development of superbug vaccines.

Objective To establish a high-throughput screening system to obtain key Staphylococcus aureus (S.aureus)secretory proteins which required for S.aureus survival in macrophages.Methods Based on our validated eukaryotic expression vector library of S.aureus secretory proteins,DNA transfection was used to obtain an RAW264.7 macrophage array expressing S.aureus secretory proteins.After the RAW264.7 cells were infected with S.aureus,the extracellular bacteria were removed to observe the intracellular surviving situation of S.aureus.Finally,the screening results were validated by the overexpression and knockout S.aureus of corresponding secretory proteins.Results The optimal transfection dose (1.0 μg/well)of plasmids for RAW264.7,multiplicity of infection (MOI,1 .0 ),and infection time (4 h after removing extracellular bacteria of S.aureus ) were established respectively.To validate the screening results,the corresponding overexpression and knockout strains were constructed.And hypothetical protein and Serine protease E were found to promote the survival of intracellular S.aureus.Conclusion We successfully construct a screening system for key secreted secretory proteins which required for S.aureus surviving in macrophages,which may advance the study of the intracellular surviving mechanism of S.aureus.

Objective To investigate the distribution of B cells in both tumor and non-tumor tissues of gastric cancer patients,analyze their phenotypic characteristics and explore the impact on T cell proliferation.Methods Immunohistochemical staining was utilized to detect the expression of B cell surface marker CD 19 in tumor and non-tumor tissues from 33 gastric cancer patients.The expression levels of chemokine receptors and immunoglobulin molecules on B cells in both tumor and non-tumor tissues were measured using flow cytometry.Chemotaxis experiments were conducted to examine the role of the CXCL12-CXCR4 axis in B cell chemotaxis.B cells isolated and purified from both tissue types were co-cultured with autologous peripheral T cells to assess their effect on T cell proliferation.Results There were significantly more B cells infiltrated in tumor tissues than those infitrated in the non-tumor tissues of gastric cancer patients(P＜0.01),and CXCR4 was highly expressed on tumor-infiltrating B cells compared with B cells derived from non-tumor tissues(P＜0.05).The Cancer Genome Atlas(TCGA)analysis indicated that the expression level of CXCL12 in tumor tissues was positively correlated with the expression level of CD19 in gastric cancer patients(r=0.15,P＜0.01).And the expression level of CXCL12 in tumor tissues of the gastric cancer patients was also positively correlated with the number of B cells infiltrated in tumor tissues.Chemotaxis experiments confirmed that the CXCL12-CXCR4 axis was involved in promoting B cell chemotaxis(P＜0.05).Although B cells in tumor and non-tumor tissues had similar levels of IgM,IgG,and IgA expression,tumor-infiltrating B cells significantly inhibited the proliferation of T cells when compared with B cells derived from non-tumor tissues(P＜0.01).Conclusion There are more B cells infiltrated in gastric cancer tissues,which may be recruited to tumor tissues through the CXCL12-CXCR4 axis,and then inhibit T cell proliferation to promote the progression of gastric cancer.

Objective To explore the mechanism which drives nimbolide(NIM)in treating acute pneumonia caused by Staphylococcus aureus(S.auteus).Methods A mouse model of acute pneumonia caused by S.auteus was constructed through endotracheal intubation.After NIM treatment,the survival rate was observed,the amount of bacteria in the lung was tested by plate culture,and the expression of inflammatory cytokines in the lung tissues was detected with ELISA.After primary cultured peritoneal macrophages(PM)were infected with S.auteus,the effect of NIM on the expression of inflammatory cytokines and activation of inflammatory pathway were studied with ELISA and Western blotting,respectively.The effect of RNF114 knockdown by lentiviral shRNA infection on inflammation responses in PM was explored with ELISA and Western blotting.Results Acute infection of S.auteus in the lung could cause acute death in the mice,while NIM treatment significantly improved the survival rate and down-regulated the levels of inflammatory cytokines in the lung.However,it had no effect on the lung colonization of S.auteus in the short term.The results of in vitro experiments indicated that NIM may regulate RNF114 function to down-regulate the phosphorylation level of ERK,inhibit the activation of MAPK pathway,and thus suppress the expression of inflammatory cytokines.Conclusion NIM may inhibit the activation of MAPK pathway by regulating the function of RNF114,and thus suppress the expression of inflammatory cytokines in the lung,and finally inhibit the death of mice with acute pulmonary hyperinflammation caused by S.auteus.

Tumor has become the major reasons cause of death,and its vaccine has become the effective tracts of treatment and prevention by enhancing the immune response of patients.However,most vaccines which are recombination subunit protein antigens are poorly immunogenic and difficult to induce a robust immune response in patients with compromised immune systems,resulting in poor marketing approval.The core component of the vaccine adjuvant can greatly enhance the strength,speed and duration of the immune response,thus becoming the key to the development of an ideal tumor vaccine.Most tumor vaccines are combined with tradition adjuvant such as aluminum,MF59 and AS adjuvant,but their products and patents are monopolized by large foreign companies.We found that natural adjuvants have many unique advantages,such as good biocompatibility and biodegradability,promoting the maturation of dendritic cell and the secretion of immune cytokines,significantly enhancing the tumor vaccine immune response,etc.In this paper,the application and future development of natural polysaccharides,saponins,flavonoid and plant virus-like particles in cancer vaccines were reviewed,which may lay a solid foundation for the development of the original and innovative adjuvants with domestic independent intellectual property rights.