OBJECTIVE To investigate the impact of lysosomal associated membrane protein 2b(Lamp2b)modification on the mucosal immune efficacy of engineered exosome-based vaccines.METHODS In vitro experiments:The murine dendritic cell line DC2.4 was transfected with a plasmid encoding the Lamp2b-RBD fusion protein.Real-time quantitative PCR and Western blotting were employed to assess Lamp2b-RBD expressions,flow cytometry was used to evaluate the proportion of Lamp2b-RBD-positive cells,and immunofluorescence staining was performed to determine their membrane localization.Exosomes were isolated via ultracentrifugation,and their morphology and particle size distribution were examined using transmission electron microscopy and nanoparticle tracking analysis.Western blotting was applied to confirm exosomal marker proteins[cluster of differentiation 9(CD9),CD63,ALG-2-interacting protein X(Alix),and Golgi marker GM130]and Lamp2b-RBD expression.In vivo experiments:① Female BALB/c mice were divided into the Lamp2b-RBD-Exo group and the lipid nanoparticle(LNP)group,and administered intratracheally for mucosal immunization.Pulmonary reten-tion was assessed by immunofluorescence staining.② Female BALB/c mice were divided into three groups:placebo group(PBS group),Lamp2b-RBD-Exo intratracheal administration group,and Lamp2b-RBD-Exo intramuscular injection group(im).Immunizations were performed on days 0 and 14,and on days 7 and 21.The titers of RBD-specific immunoglobulin G(IgG)in serum and RBD-specific IgA and IgG antibodies in bronchoalveolar lavage fluid were determined by enzyme-linked immunosor-bent assay(ELISA).RESULTS In vitro experiments:Lamp2b-RBD-positive cells accounted for 71.16％.Lamp2b-RBD mRNA levels were upregulated 1 979-fold compared with controls,with Lamp2b-RBD proteins localized on the cell membrane.Purified engineered exosomes displayed regular morphology,expressed CD9,CD63,and Alix but not GM130,had an average diameter of approximately 124 nm,and carried 3 009 pg of RBD protein per 1×109 exosomes.In vivo experiments:At 4 h after administra-tion,fluorescence signals were observed in the lung tissues of both the Lamp2b-RBD-Exo and LNPs groups.At 24 h,the fluorescence signal in the LNPs group shifted to the liver,while in the Lamp2b-RBD-Exo group,the fluorescence expanded from the trachea to the bronchioles and lung tissue,showing significantly better distribution and retention capacity than the LNPs group.Seven days after immuniza-tion,both the Lamp2b-RBD-Exo and Lamp2b-RBD-Exo(im)groups induced RBD-specific IgG antibody titers.At 21 days after immunization,Lamp2b-RBD-Exo elicited a higher level of RBD-specific immune response,with serum IgG titers reaching 1∶8 100 and bronchoalveolar lavage fluid(BALF)IgA titers reaching 1∶300.No RBD-specific IgA antibody titers were detected in the BALF of the Lamp2b-RBD-Exo(im)group.CONCLUSION Lamp2b-RBD modification enables efficient RBD protein loading and enhances pulmonary retention of engineered exosomes,thereby inducing potent antigen-specific mucosal immune responses.

OBJECTIVE To investigate the impact of lysosomal associated membrane protein 2b(Lamp2b)modification on the mucosal immune efficacy of engineered exosome-based vaccines.METHODS In vitro experiments:The murine dendritic cell line DC2.4 was transfected with a plasmid encoding the Lamp2b-RBD fusion protein.Real-time quantitative PCR and Western blotting were employed to assess Lamp2b-RBD expressions,flow cytometry was used to evaluate the proportion of Lamp2b-RBD-positive cells,and immunofluorescence staining was performed to determine their membrane localization.Exosomes were isolated via ultracentrifugation,and their morphology and particle size distribution were examined using transmission electron microscopy and nanoparticle tracking analysis.Western blotting was applied to confirm exosomal marker proteins[cluster of differentiation 9(CD9),CD63,ALG-2-interacting protein X(Alix),and Golgi marker GM130]and Lamp2b-RBD expression.In vivo experiments:① Female BALB/c mice were divided into the Lamp2b-RBD-Exo group and the lipid nanoparticle(LNP)group,and administered intratracheally for mucosal immunization.Pulmonary reten-tion was assessed by immunofluorescence staining.② Female BALB/c mice were divided into three groups:placebo group(PBS group),Lamp2b-RBD-Exo intratracheal administration group,and Lamp2b-RBD-Exo intramuscular injection group(im).Immunizations were performed on days 0 and 14,and on days 7 and 21.The titers of RBD-specific immunoglobulin G(IgG)in serum and RBD-specific IgA and IgG antibodies in bronchoalveolar lavage fluid were determined by enzyme-linked immunosor-bent assay(ELISA).RESULTS In vitro experiments:Lamp2b-RBD-positive cells accounted for 71.16％.Lamp2b-RBD mRNA levels were upregulated 1 979-fold compared with controls,with Lamp2b-RBD proteins localized on the cell membrane.Purified engineered exosomes displayed regular morphology,expressed CD9,CD63,and Alix but not GM130,had an average diameter of approximately 124 nm,and carried 3 009 pg of RBD protein per 1×109 exosomes.In vivo experiments:At 4 h after administra-tion,fluorescence signals were observed in the lung tissues of both the Lamp2b-RBD-Exo and LNPs groups.At 24 h,the fluorescence signal in the LNPs group shifted to the liver,while in the Lamp2b-RBD-Exo group,the fluorescence expanded from the trachea to the bronchioles and lung tissue,showing significantly better distribution and retention capacity than the LNPs group.Seven days after immuniza-tion,both the Lamp2b-RBD-Exo and Lamp2b-RBD-Exo(im)groups induced RBD-specific IgG antibody titers.At 21 days after immunization,Lamp2b-RBD-Exo elicited a higher level of RBD-specific immune response,with serum IgG titers reaching 1∶8 100 and bronchoalveolar lavage fluid(BALF)IgA titers reaching 1∶300.No RBD-specific IgA antibody titers were detected in the BALF of the Lamp2b-RBD-Exo(im)group.CONCLUSION Lamp2b-RBD modification enables efficient RBD protein loading and enhances pulmonary retention of engineered exosomes,thereby inducing potent antigen-specific mucosal immune responses.

OBJECTIVE To investigate the impact of vesicular stomatitis virus envelope glycopro-tein-G(VSV-G)modification on the mucosal immune efficacy of antigen-loaded engineered exosome vaccines.METHODS In vitro experiments:Dendritic cells(DCs)were divided into three groups:cell-control(treated with culture medium),receptor binding domain(RBD)(transfected with plasmid RBD),and RBD+VSV-G(co-transfected with plasmids RBD and VSV-G).Expression levels of RBD and VSV-G were assessed using Western blotting,flow cytometry,and immunofluorescence.Exosomes were extracted via ultracentrifugation,whose morphology,size distribution,and marker proteins were analyzed using transmission electron microscopy,nanoparticle tracking analysis,and Western blotting that confirmed the expressions of RBD and VSV-G in the exosomes.In vivo experiments:① Female BALB/c mice were divided into the control group Mock exosomes(Mock-Exo)(derived from the supernatant of cell-control),RBD decorated exosomes(RBD-Exo)(derived from the RBD cell supernatant),and RBD and VSV-G decorated exosomes(RBD+VSV-G-Exo)(derived from RBD+VSV-G cell supernatant).Follow-ing intranasal immunization with the respective vaccines,the nasal retention effects were evaluated using in vivo imaging.Flow cytometry was used to assess the ability to recruit immune cells to the nasal tissue.Serum RBD-specific immunoglobulin G(IgG)and mucosal immunoglobulin A(IgA)(bronchoal-veolar lavage fluid/nasal wash)were quantified at 7 and 21 d post-immunization by enzyme-linked immuno-sorbent assay.Body weight changes were monitored and key serum biochemical parameters along with histopathological damage to major organs were analyzed following immunization.② Female BALB/c mice were divided into the Mock-Exo group(intranasally inoculated with Mock-Exo),RBD+VSV-G-Exo group(intranasally inoculated with RBD+VSV-G-Exo),and RBD+VSV-G-Exo(im)group(intramus-cularly injected with RBD+VSV-G-Exo).RESULTS In vitro experiments:RBD and VSV-G were successfully expressed in cells,with positive rates of RBD+and VSV-G+cells at 64.4%and 31.2%,respectively.The extracted exosomes exhibited regular morphology and qualified purity,with a particle size of approximately 138 nm and successfully loaded RBD and VSV-G proteins.In vivo experiments:Compared to Mock-Exo and RBD-Exo,RBD+VSV-G-Exo prolonged nasal retention time to 96 h and markedly increased the numbers of CD49B+natural killer cells,CD11c+dendritic cells,and F4/80+macrophages in nasal tissues.RBD+VSV-G-Exo induced robust RBD-specific immune responses,with serum IgG titers,BALF IgA titers,and nasal wash IgA titers reaching 1∶5 215,1∶2 560,1∶1 114,respec-tively.In contrast,no RBD-specific IgA antibody titers were detected in the BALF and nasal wash of mice treated with RBD+VSV-G-Exo(im).Mice showed stable body weight gain during 30 d post-immu-nization.Major serum biochemical indices were within normal reference ranges,and no obvious patho-logical changes were observed in major organs or olfactory bulbs 7 d after immunization.CONCLU-SION VSV-G modification extends the retention time of engineered exosome vaccines in nasal tissues,enhance their ability to recruit immune cells,and induce a high-level antigen-specific respiratory mucosal immune response.

OBJECTIVE To investigate the impact of vesicular stomatitis virus envelope glycopro-tein-G(VSV-G)modification on the mucosal immune efficacy of antigen-loaded engineered exosome vaccines.METHODS In vitro experiments:Dendritic cells(DCs)were divided into three groups:cell-control(treated with culture medium),receptor binding domain(RBD)(transfected with plasmid RBD),and RBD+VSV-G(co-transfected with plasmids RBD and VSV-G).Expression levels of RBD and VSV-G were assessed using Western blotting,flow cytometry,and immunofluorescence.Exosomes were extracted via ultracentrifugation,whose morphology,size distribution,and marker proteins were analyzed using transmission electron microscopy,nanoparticle tracking analysis,and Western blotting that confirmed the expressions of RBD and VSV-G in the exosomes.In vivo experiments:① Female BALB/c mice were divided into the control group Mock exosomes(Mock-Exo)(derived from the supernatant of cell-control),RBD decorated exosomes(RBD-Exo)(derived from the RBD cell supernatant),and RBD and VSV-G decorated exosomes(RBD+VSV-G-Exo)(derived from RBD+VSV-G cell supernatant).Follow-ing intranasal immunization with the respective vaccines,the nasal retention effects were evaluated using in vivo imaging.Flow cytometry was used to assess the ability to recruit immune cells to the nasal tissue.Serum RBD-specific immunoglobulin G(IgG)and mucosal immunoglobulin A(IgA)(bronchoal-veolar lavage fluid/nasal wash)were quantified at 7 and 21 d post-immunization by enzyme-linked immuno-sorbent assay.Body weight changes were monitored and key serum biochemical parameters along with histopathological damage to major organs were analyzed following immunization.② Female BALB/c mice were divided into the Mock-Exo group(intranasally inoculated with Mock-Exo),RBD+VSV-G-Exo group(intranasally inoculated with RBD+VSV-G-Exo),and RBD+VSV-G-Exo(im)group(intramus-cularly injected with RBD+VSV-G-Exo).RESULTS In vitro experiments:RBD and VSV-G were successfully expressed in cells,with positive rates of RBD+and VSV-G+cells at 64.4%and 31.2%,respectively.The extracted exosomes exhibited regular morphology and qualified purity,with a particle size of approximately 138 nm and successfully loaded RBD and VSV-G proteins.In vivo experiments:Compared to Mock-Exo and RBD-Exo,RBD+VSV-G-Exo prolonged nasal retention time to 96 h and markedly increased the numbers of CD49B+natural killer cells,CD11c+dendritic cells,and F4/80+macrophages in nasal tissues.RBD+VSV-G-Exo induced robust RBD-specific immune responses,with serum IgG titers,BALF IgA titers,and nasal wash IgA titers reaching 1∶5 215,1∶2 560,1∶1 114,respec-tively.In contrast,no RBD-specific IgA antibody titers were detected in the BALF and nasal wash of mice treated with RBD+VSV-G-Exo(im).Mice showed stable body weight gain during 30 d post-immu-nization.Major serum biochemical indices were within normal reference ranges,and no obvious patho-logical changes were observed in major organs or olfactory bulbs 7 d after immunization.CONCLU-SION VSV-G modification extends the retention time of engineered exosome vaccines in nasal tissues,enhance their ability to recruit immune cells,and induce a high-level antigen-specific respiratory mucosal immune response.

As a natural drug delivery carrier with rough and porous surface and hollow core， yeast microcapsules have good safety， high targeting and high stability， and have excellent application prospects in oral drug delivery systems. Yeast cells can be treated and washed with acid-base and organic solvents to obtain loose and porous yeast microcapsules. Yeast microcapsules can encapsulate drugs through electrostatic interactions， passive diffusion， hydrophobic interaction and other methods. The surface of yeast microcapsules is mainly composed of β-glucan， which can maintain stability in the gastrointestinal environment； it can be recognized by the surface-related receptors of immune cells， thus activating the immune response， and can be transported to the lesion site with the movement of lymphocytes after being ingested. Yeast microcapsules are safe and very suitable for delivering vaccines， anti-inflammatory drugs， and anti-tumor drugs. They can not only achieve oral delivery of the aforementioned drugs， but also enhance drug efficacy and improve drug targeting. In the future， more research on systemic transport mechanisms or the development of more efficient combination drug delivery systems can be carried out to fully exhibit the clinical value of yeast microcapsules.

Immunotherapy has revolutionized the landscape of cancer treatment. However, single immunotherapy only works well in a small subset of patients. Combined immunotherapy with antitumor synergism holds considerable potential to boost the therapeutic outcome. Nevertheless, the synergistic, additive or antagonistic antitumor effects of combined immunotherapies have been rarely explored. Herein, we established a novel combined cancer treatment modality by synergizing p21-activated kinase 4 (PAK4) silencing with immunogenic phototherapy in engineered extracellular vesicles (EVs) that were fabricated by coating M1 macrophage-derived EVs on the surface of the nano-complex cores assembled with siRNA against PAK4 and a photoactivatable polyethyleneimine. The engineered EVs induced potent PAK4 silencing and robust immunogenic phototherapy, thus contributing to effective antitumor effects in vitro and in vivo. Moreover, the antitumor synergism of the combined treatment was quantitatively determined by the CompuSyn method. The combination index (CI) and isobologram results confirmed that there was an antitumor synergism for the combined treatment. Furthermore, the dose reduction index (DRI) showed favorable dose reduction, revealing lower toxicity and higher biocompatibility of the engineered EVs. Collectively, the study presents a synergistically potentiated cancer treatment modality by combining PAK4 silencing with immunogenic phototherapy in engineered EVs, which is promising for boosting the therapeutic outcome of cancer immunotherapy.

Respiratory mucosal immune system is the body''s first line of defense against infection.Since the outbreak of novel coronavirus disease 2019 (COVID-19) in 2019,nasal mucosal immune vaccine, with its ability to induce cellular, humoral and mucosal triple immune responses, has become a research hotspot.This article focuses on novel coronavirus, with an understanding of its structure and pathogenesis, a brief introduction to the immune mechanism of nasal mucosa, a summary of the different types of nasal mucosal immune vaccines and their clinical research, aiming to provide some theoretical reference for the development of new vaccines, and exploration of the best methods and strategies to combat COVID-19.

Objective: This study aimed to analyze the association between the characteristics of egocentric network and HIV prevalence among men who have sex with men (MSM) through social network analysis. Methods: The study was conducted in Guangzhou city from November 2016 to June 2017 using convenient sampling method. Participants were recruited from 13 voluntary counseling and testing (VCT) locations. Data were collected by using nomination generation and nomination interpretation methods. Questionnaire includes two parts, the first part about the social tie, and the second one about social demography and behavioral characteristics of respondents and their nominees. The multivariate logistic regression was applied to quantify the association. Results: 8.67%(93/1 073) HIV antibody positive MSM had been detected in 1 073 respondents who nominated 4 301 partners in total. Compared to egocentric sexual network with a size of 1-2, the size of sexual network larger than 3 (OR=1.68, 95%CI: 1.07-2.65) were associated with HIV infection. Compared to egocentric risk sexual network with a size of 1-2, the size of risk sexual networks larger than 3 (OR=1.87, 95%CI: 1.06-3.31) were associated with HIV infection. There were no significant association between marital similarity of respondents and their nominees, the type of the relationship of sexual partners and HIV prevalence (P>0.05). Conclusion The composition of social network in MSM is related to their susceptibility of HIV infection. MSM population with a large sexual network is more susceptible to HIV infection.