An unbroken network of interactions connecting flagellin domains is required for motility in viscous environments.

In its simplest form, bacterial flagellar filaments are composed of flagellin proteins with just two helical inner domains, which together comprise the filament core. Although this minimal filament is sufficient to provide motility in many flagellated bacteria, most bacteria produce flagella composed of flagellin proteins with one or more outer domains arranged in a variety of supramolecular architectures radiating from the inner core. Flagellin outer domains are known to be involved in adhesion, proteolysis and immune evasion but have not been thought to be required for motility. Here we show that in the Pseudomonas aeruginosa PAO1 strain, a bacterium that forms a ridged filament with a dimerization of its flagellin outer domains, motility is categorically dependent on these flagellin outer domains. Moreover, a comprehensive network of intermolecular interactions connecting the inner domains to the outer domains, the outer domains to one another, and the outer domains back to the inner domain filament core, is required for motility. This inter-domain connectivity confers PAO1 flagella with increased stability, essential for its motility in viscous environments. Additionally, we find that such ridged flagellar filaments are not unique to Pseudomonas but are, instead, present throughout diverse bacterial phyla.

MiR-9 promotes G-MDSC recruitment and tumor proliferation by targeting SOCS3 in breast cancer.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of cells that differentiate from myeloid cells, proliferate in cancer and inflammatory reactions, and mainly exert immunosuppressive functions. Nonetheless, the precise mechanisms that dictate both the accumulation and function of MDSCs remain only partially elucidated. In the course of our investigation, we observed a positive correlation between the content of MDSCs especially G-MDSCs and miR-9 level in the tumor tissues derived from miR-9 knockout MMTV-PyMT mice and 4T1 tumor-bearing mice with miR-9 overexpression. Combined with RNA-seq analysis, we identified SOCS2 and SOCS3 as direct targets of miR-9. Additionally, our research unveiled the pivotal role of the CCL5/CCR5 axis in orchestrating the chemotactic recruitment of G-MDSCs within the tumor microenvironment, a process that is enhanced by miR-9. These findings provide fresh insights into the molecular mechanisms governing the accumulation of MDSCs within the framework of breast cancer development.

The contribution of Ca and Mg to the accumulation of amino acids in maize: from the response of physiological and biochemical processes.

BACKGROUND: The quality of maize kernels is significantly enhanced by amino acids, which are the fundamental building blocks of proteins. Meanwhile, calcium (Ca) and magnesium (Mg), as important nutrients for maize growth, are vital in regulating the metabolic pathways and enzyme activities of amino acid synthesis. Therefore, our study analyzed the response process and changes of amino acid content, endogenous hormone content, and antioxidant enzyme activity in kernels to the coupling addition of sugar alcohol-chelated Ca and Mg fertilizers with spraying on maize. RESULT: (1) The coupled addition of Ca and Mg fertilizers increased the Ca and Mg content, endogenous hormone components (indole-3-acetic acid, IAA; gibberellin, GA; zeatin riboside, ZR) content, antioxidant enzyme activity, and amino acid content of maize kernels. The content of Ca and Mg in kernels increased with the increasing levels of Ca and Mg fertilizers within a certain range from the filling to the wax ripening stage, and significantly positively correlated with antioxidant enzyme activities. (2) The contents of IAA, GA, and ZR continued to rise, and the activities of superoxide dismutase (SOD) and catalase (CAT) were elevated, which effectively enhanced the ability of cells to resist oxidative damage, promoted cell elongation and division, and facilitated the growth and development of maize. However, the malondialdehyde (MDA) content increased consistently, which would attack the defense system of the cell membrane plasma to some extent. (3) Leucine (LEU) exhibited the highest percentage of essential amino acid components and a gradual decline from the filling to the wax ripening stage, with the most substantial beneficial effect on essential amino acids. (4) CAT and SOD favorably governed essential amino acids, while IAA and MDA negatively regulated them. The dominant physiological driving pathway for the synthesis of essential amino acids was "IAA-CAT-LEU", in which IAA first negatively drove CAT activity, and CAT then advantageously controlled LEU synthesis. CONCLUSION: These findings provide a potential approach to the physiological and biochemical metabolism of amino acid synthesis, and the nutritional quality enhancement of maize kernel.

Bacterial effector targeting of a plant iron sensor facilitates iron acquisition and pathogen colonization.

Acquisition of nutrients from different species is necessary for pathogen colonization. Iron is an essential mineral nutrient for nearly all organisms, but little is known about how pathogens manipulate plant hosts to acquire iron. Here, we report that AvrRps4, an effector protein delivered by Pseudomonas syringae bacteria to plants, interacts with and targets the plant iron sensor protein BRUTUS (BTS) to facilitate iron uptake and pathogen proliferation in Arabidopsis thaliana. Infection of rps4 and eds1 by P. syringae pv. tomato (Pst) DC3000 expressing AvrRps4 resulted in iron accumulation, especially in the plant apoplast. AvrRps4 alleviates BTS-mediated degradation of bHLH115 and ILR3(IAA-Leucine resistant 3), two iron regulatory proteins. In addition, BTS is important for accumulating immune proteins Enhanced Disease Susceptibility1 (EDS1) at both the transcriptional and protein levels upon Pst (avrRps4) infections. Our findings suggest that AvrRps4 targets BTS to facilitate iron accumulation and BTS contributes to RPS4/EDS1-mediated immune responses.

A first-principles study of 2D single-layer SiP as anode materials for lithium-ion batteries and sodium-ion batteries.

The promotion of lithium-ion batteries and sodium-ion batteries is limited by the deficiency of suitable anode materials with desired electrochemical properties. In this work, the models of 2D single-layer SiP are constructed to explore its potential as an anode material for LIBs and SIBs using density functional theory (DFT). The diffusion of Li in bulk SiP is anisotropic. There is a low diffusion energy barrier of 0.28 eV along the X-axis. The low surface exfoliation energy suggests that there is a high probability of preparing 2D single-layer SiP experimentally. Its structure stability is verified by ab initio molecular dynamics (AIMD) simulations at 300 K and 400 K. The intercalation and diffusion behaviors of Li/Na on 2D single-layer SiP indicate that Li/Na tends to diffuse along the X-axis direction of 2D single-layer SiP. The diffusion energy barrier of Li/Na on 2D single-layer SiP is lower compared to that of bulk SiP. The conductivity of 2D single-layer SiP is improved after lithiation due to the upshift of Fermi levels. 2D single-layer SiP has a lower average open circuit voltage (1.50 V for LIBs and 1.08 V for SIBs) and a high theoretical capacity (520 mA h g-1). Hence, 2D single-layer SiP can be an ideal anode material for LIBs and SIBs.

Hsa_circ_0136666 stimulates gastric cancer progression and tumor immune escape by regulating the miR-375/PRKDC Axis and PD-L1 phosphorylation.

BACKGROUND: Targeted drugs are not quite effective for prolonging the survival of patients with gastric cancer due to off-target effects as well as tumor immune escape mechanisms. Circular RNAs widely exist in tumor regions as biomarkers and can be developed as effective drug targets. METHODS: Western blot, QRT-PCR, fluorescence in situ hybridization, and flow cytometry were used to investigate the function of hsa_circ_0136666 in promoting the proliferation of gastric cancer cells. Tissue immunofluorescence, enzyme-linked immunosorbent assay (ELISA), as well as flow cytometric analysis, was conducted to explore the process of tumor immune evasion in tumor-bearing mice. The differences of circRNA expression in clinical samples were analyzed through tissue microarray FISH. The effect of siRNA on improving the efficacy of anti-PDL1 drugs and suppressing the immune microenvironment was evaluated by the coadministration model. RESULTS: We demonstrated that hsa_circ_0136666 was widely and highly expressed in gastric cancer tissues and cells. Functionally, hsa_circ_0136666 promoted gastric cancer tumor proliferation and tumor microenvironment formation, leading to tumorigenesis immune escape, and this effect was dependent on CD8 + T cells. Mechanistically, we confirmed that hsa_circ_0136666 competitively upregulated PRKDC expression by sponging miR-375-3p, regulating immune checkpoint proteins, prompting phosphorylation of PD-L1 to preventing its degradation, driving PD-L1 aggregation and suppressing immune function, thereby impairing cancer immune responses. In terms of application, we found that LNP-siRNA effectively improved anti-PDL1 drug efficacy and inhibited immune escape. CONCLUSION: Our results reveal an oncogenic role played by hsa_circ_0136666 in gastric cancer, driving PD-L1 phosphorylation via the miR-375/PRKDC signaling axis, prompting immune escape. This work proposes a completely new pathogenic mechanism of gastric cancer, uncovers a novel role for hsa_circ_0136666 as an immune target, and provides a rationale for enhancing the efficacy of anti-PD-L1 therapy for gastric cancer.

Design and Construction of Enzyme-Based Electrochemical Gas Sensors.

The demand for the ubiquitous detection of gases in complex environments is driving the design of highly specific gas sensors for the development of the Internet of Things, such as indoor air quality testing, human exhaled disease detection, monitoring gas emissions, etc. The interaction between analytes and bioreceptors can described as a "lock-and-key", in which the specific catalysis between enzymes and gas molecules provides a new paradigm for the construction of high-sensitivity and -specificity gas sensors. The electrochemical method has been widely used in gas detection and in the design and construction of enzyme-based electrochemical gas sensors, in which the specificity of an enzyme to a substrate is determined by a specific functional domain or recognition interface, which is the active site of the enzyme that can specifically catalyze the gas reaction, and the electrode-solution interface, where the chemical reaction occurs, respectively. As a result, the engineering design of the enzyme electrode interface is crucial in the process of designing and constructing enzyme-based electrochemical gas sensors. In this review, we summarize the design of enzyme-based electrochemical gas sensors. We particularly focus on the main concepts of enzyme electrodes and the selection and design of materials, as well as the immobilization of enzymes and construction methods. Furthermore, we discuss the fundamental factors that affect electron transfer at the enzyme electrode interface for electrochemical gas sensors and the challenges and opportunities related to the design and construction of these sensors.

Kinetically Accelerated Lithium Storage in High-Entropy (LiMgCoNiCuZn)O Enabled By Oxygen Vacancies.

High-entropy oxides (HEOs) are gradually becoming a new focus for lithium-ion battery (LIB) anodes due to their vast element space/adjustable electrochemical properties and unique single-phase retention ability. However, the sluggish kinetics upon long cycling limits their further generalization. Here, oxygen vacancies with targeted functionality are introduced into rock salt-type (MgCoNiCuZn)O through a wet-chemical molten salt strategy to accelerate the ion/electron transmission. Both experimental results and theoretical calculations reveal the potential improvement of lithium storage, charge transfer, and diffusion kinetics from HEO surface defects, which ultimately leads to enhanced electrochemical properties. The currently raised strategy offers a modular approach and enlightening insights for defect-induced HEO-based anodes.

Probiotics for the Treatment of Gastric Diseases.

Common gastric diseases include chronic gastritis, gastric ulcers and gastric cancer. The etiology of gastric diseases is complicated, including genetics, diet, excessive smoking and drinking, environmental factors, and bacterial infections. As live microorganisms, probiotics can confer health benefits to the host. At present, probiotics have been widely used in the preparation of foods, health products, and medicines. Due to their positive effects in improving diarrhea, constipation, alleviating allergies, enhancing immunity, and maintaining intestinal homeostasis, studies worldwide have focused on whether probiotics also provide therapeutic effects on gastric diseases. Thus, this review summarizes the possible mechanism of probiotics in the treatment of gastric diseases and provides a reference for expanding not only their application but also that of other microecological agents.

Tanshinone IIA inhibits gastric cancer cell stemness through inducing ferroptosis.

Tanshinone IIA is the active constituent extracted from Salvia Miltiorrhza. Numerous studies have shown that Tanshinone IIA could inhibit tumor proliferation and metastasis, including gastric cancer. However, the effect of Tanshinone IIA on gastric cancer cell stemness stays unclear. Here, we found that Tanshinone IIA could reduce gastric cancer cell stemness through detecting spheroid-forming, flow cytometry analysis, and the expression of stemness markers (OCT3/4, ALDH1A1, and CD44). Mechanistically, Tanshinone IIA increased the level of lipid peroxides and decreased glutathione level in gastric cancer cells, both of which are the markers of ferroptosis. Similarly, ferroptosis inducers (erastin, sulfasalazine, and sorafenib) reduced gastric cancer cell stemness. Additionally, the inhibitory effects of Tanshinone IIA on GC cell stemness were reversed by ferroptosis inhibitor (Fer-1) or overexpression of SLC7A11, which is a critical ferroptosis inhibitor. Therefore, we revealed that Tanshinone IIA inhibited the stemness of gastric cancer cells partly through inducing ferroptosis.

CD4+ CD8αα+ T cells in the gastric epithelium mediate chronic inflammation induced by Helicobacter felis.

CD4+ CD8αα+ double-positive intraepithelial T lymphocytes (DP T cells), a newly characterized subset of intraepithelial T cells, are reported to contribute to local immunosuppression. However, the presence of DP T cells in Helicobacter. pylori -induced gastritis and their relationship with disease prognosis has yet to be elucidated. In this study, a chronic gastritis model was established by infecting mice with Helicobacter felis. Gastric-infiltrating lymphocytes were isolated from these mice and analyzed by flow cytometry. The frequency of DP T cells in H. felis-induced gastritis mice was higher than that in uninfected mice. The gastric DP T cells were derived from lamina propria cells but were predominantly distributed in the gastric epithelial layer. These gastric DP T cells also exhibited anti-inflammatory functions, and they inhibited the maturation of dendritic cells and proliferation of CD4+ T lymphocytes in vitro. Elimination of DP T cells simultaneously resulted in severe gastritis and a reduction of H. felis load in vivo. Finally, vaccine mixed with different adjuvants was used to explore the relationship between vaccine efficacy and DP cells. Silk fibroin as the vaccine delivery system enhanced vaccine efficacy by reducing the number of DP T cells. This study demonstrated that DP T cells perform an immunosuppressive role in Helicobacter felis-induced gastritis, and consequently, DP T cells may affect disease prognosis and vaccine efficacy.

Helicobacter pylori induces gastric cancer via down-regulating miR-375 to inhibit dendritic cell maturation.

BACKGROUND: Recent studies and clinical samples have demonstrated that Helicobacter pylori could induce the downregulation of miR-375 in the stomach and promote gastric carcinogenesis. However, whether the immune cells are affected by Helicobacter pylori due to the downregulation of miR-375 is unclear. MATERIALS AND METHODS: In this study, we constructed an overexpression and knockdown of miR-375 and Helicobacter pylori infection cell models in vitro. In addition, the maturity of dendritic cells (DCs) and the expression of IL-6, IL-10, and VEGF at the transcriptional and translational levels were analyzed. Changes in the JAK2-STAT3 signaling pathway were detected. In vivo, the number changes in CD4+ T and CD8+ T cells and the size changes of tumors via models of transplantable subcutaneous tumors were also analyzed. RESULTS: A cell model of Helicobacter pylori and gastric cancer was used to identify the expression of miR-375 and the maturity of dendritic cells. This study found that Helicobacter pylori could downregulate miR-375, which regulates the expression of cytokines IL-6, IL-10, and VEGF in the stomach. MiR-375 regulated the expression of cytokines IL-6, IL-10, and VEGF through the JAK2-STAT3 signaling pathway in vitro. In addition, we found that Helicobacter pylori regulates the maturation of dendritic cells through miR-375. These results were further verified in vivo, and miR-375 diminishes tumor size was also demonstrated. This study showed that immature DCs caused a decrease in the number of CD4+ and CD8+ T cells. CONCLUSIONS: This study demonstrated that Helicobacter pylori can inhibit miRNA-375 expression in the stomach. Downregulated miR-375 activates the JAK2-STAT3 pathway. Activating the JAK2-STAT3 signaling pathway promotes the secretion of IL-6, IL-10, and VEGF, leading to immature differentiation of DCs and induction of gastric cancer.

The impact of lung microbiota dysbiosis on inflammation.

Host-microbiota interaction plays fundamental roles in the homeostasis of mucosal immunity. Dysbiosis of intestinal microbiota has been demonstrated to participate in various immune responses and many multifactorial diseases. Study of intestinal microbiota has moved beyond the consequences of dysbiosis to the causal microbiota associated with diseases. However, studies of pulmonary microbiota and its dysbiosis are still in their infancy. Improvement of culture-dependent and -independent techniques has facilitated our understanding of lung microbiota that not only exists in healthy lung tissue but also exerts great impact on immune responses under both physiological and pathological conditions. In this review, we summarize recent progresses of lung microbiota dysbiosis and its impact on the local immune system that determines the balance of tolerance and inflammation. We discuss the causal roles of pulmonary dysbiosis under disease settings, and propose that the interaction between lung microbiota and host is critical for establishing the immune homeostasis in lung.

Determining optimal mulching, planting density, and nitrogen application to increase maize grain yield and nitrogen translocation efficiency in Northwest China.

BACKGROUND: The combination of mulch with N fertilizer application is a common agronomic technique used in the production of rainfed maize (Zea mays L.) to achieve higher yields under conditions of optimum planting density and adequate N supply. However, the combined effects of mulch, planting density, and N fertilizer application rate on plant N uptake and N translocation efficiency are not known. The objective of this study was to quantify the interaction effect of mulch, planting density, and N fertilizer application rate on maize grain yield, N uptake, N translocation, and N translocation efficiency. The experiment was arranged in a randomized complete block design with three factors (2 mulch levels × 2 planting densities × 4 N fertilizer application rates) replicated four times. RESULTS: There was a significant interaction among mulch, plant density, and N fertilizer on maize grain yield, kernel number per cob, N uptake, N translocation, and N translocation efficiency. Averaged over the 3 years of the study, total plant N uptake at silking ranged from 79 to 149 kg N ha- 1 with no mulch and from 76 to 178 kg N ha- 1 with mulch. The N uptake at silking in different plant organs ranked as leaf > grain > stem > cob. Averaged across all factors, the highest N translocation was observed in leaves, which was 59.4 and 88.7% higher than observed in stems and ears, respectively. The mean vegetative organ N translocation efficiency averaged over mulch, planting density, and N fertilizer application rate treatments decreased in the order of leaf > stem > cob. CONCLUSIONS: Mulch, planting density, and N fertilizer application rate not only have significant effects on improving maize grain yield and NUE, but also on N uptake, N translocation, and N translocation efficiency. Our results showed clearly that under high planting density, the combination of mulch and moderate N fertilizer application rate was the optimal strategy for increasing maize grain yield and N use efficiency.

The CCR2 3'UTR functions as a competing endogenous RNA to inhibit breast cancer metastasis.

Diverse RNA transcripts acting as competing endogenous RNAs (ceRNAs) can co-regulate each other's expression by competing for shared microRNAs. CCR2 protein, the receptor for CCL2, is implicated in cancer progression. However, we found that a higher CCR2 mRNA level is remarkably associated with prolonged survival of breast cancer patients. These conflicting results prompted us to study the non-coding function of CCR2 mRNA. We found that the CCR2 3' untranslated region (UTR) inhibited MDA-MB-231 and MCF-7 cell metastasis by repressing epithelial-mesenchymal transition (EMT) in vitro, and suppressed breast cancer metastasis in vivo Mechanistically, the CCR2 3'UTR modulated the expression of the RhoGAP protein STARD13 via acting as a STARD13 ceRNA in a microRNA-dependent and protein coding-independent manner. The CCR2 3'UTR blocked the activation of RhoA-ROCK1 pathway, which is the downstream effector of STARD13, and thus decreased the phosphorylation level of myosin light chain 2 (MLC2) and formation of F-actin. Additionally, the function of the CCR2 3'UTR was dependent on STARD13 expression. In conclusion, our results confirmed that the CCR2 3'UTR acts as a metastasis suppressor by acting as a ceRNA for STARD13 and thus inhibiting RhoA-ROCK1-MLC-F-actin pathway in breast cancer cells.This article has an associated First Person interview with the first author of the paper.

miR-125a-3p inhibits ERα transactivation and overrides tamoxifen resistance by targeting CDK3 in estrogen receptor-positive breast cancer.

Tamoxifen (TAM) is a major adjuvant therapy for patients who are diagnosed with estrogen receptor-α (ER)-positive breast cancer; however, TAM resistance occurs often during treatment and the underlying mechanism is unclear. Here, we report that miR-125a-3p inhibits ERα transcriptional activity and, thus, ER+ breast cancer cell proliferation, which causes cell-cycle arrest at the G1/S stage, inducing apoptosis and suppressing tumor growth by targeting cyclin-dependent kinase 3 (CDK3) in vitro and in vivo. In addition, CDK3 and miR-125a-3p expression levels were measured in 37 cancerous tissues paired with noncancerous samples, and their expression levels were negatively associated with miR-125a-3p level. Of interest, miR-125a-3p level is down-regulated in MCF-7 TAM-resistant (TamR) cells. Of more importance, up-regulation of miR-125a-3p resensitizes MCF-7 TamR cells to TAM, which is dependent on CDK3 expression. These results suggest that miR-125a-3p can function as a novel tumor suppressor in ER+ breast cancer by targeting CDK3, which may be a potential therapeutic approach for TamR breast cancer therapy.-Zheng, L., Meng, X., Li, X., Zhang, Y., Li, C., Xiang, C., Xing, Y., Xia, Y., Xi, T. miR-125a-3p inhibits ERα transactivation and overrides tamoxifen resistance by targeting CDK3 in estrogen receptor-positive breast cancer.

Vaccine-induced gastric CD4+ tissue-resident memory T cells proliferate in situ to amplify immune response against Helicobacter pylori insult.

BACKGROUND: Tissue-resident memory T cells accelerate the clearance of pathogens during recall response. However, whether CD4+ TRM cells themselves can provide gastric immunity is unclear. MATERIALS AND METHODS: We established a parabiosis model between the enhanced green fluorescent protein and wild-type mice that the circulation system was shared, and the wild-type partner was vaccinated with H pylori vaccine composed of CCF and silk fibroin in gastric subserous layer to induce gastric EGFP+ CD4+ TRM cells. Antigen-specific EGFP+ CD4+ T cells and proliferous TRM cells were analyzed by flow cytometry. The colonization of H pylori was detected by quantitative real-time PCR. EGFP+ CD4+ TRM cells and the inflammation of the stomach were observed by histology. RESULTS: A parabiosis animal model was employed to identify the cells that introduced by vaccination in GSL. Antigen-specific EGFP+ CD4+ T cells could be detected at day 7 post-vaccination. Thirty days later, EGFP+ CD4+ TRM cells were established with a phenotype of CD69+ CD103- . Of note, we found that when circulating lymphocytes were depleted by FTY720 administration, these TRM cells could proliferate in situ and differentiate into effector Th1 cells after H pylori challenge. A decrease in H pylori colonization was observed in the vaccinated mice but not unvaccinated mice. Further, we found that although FTY720 was administrated, mounted pro-inflammatory myeloid cells still emerged in the stomach of the vaccinated mice, which might contribute to the reduction of H pylori colonization. CONCLUSIONS: Our study reveals that H pylori vaccine-induced CD4+ TRM cells can proliferate and differentiate in situ to enhance gastric local immunity during recall response.

Shape of gastrointestinal immunity with non-genetically modified Lactococcus lactis particles requires commensal bacteria and myeloid cells-derived TGF-ß1.

Heat-killed probiotics or microbial autologous components show multiple activities on modulating host immune responses towards tolerance or vice versus aggressiveness. Gram-positive enhancer matrix particles (GEMs), the non-genetically modified particles which composed of the cell wall derived from Lactococcus lactis (L. lactis), were used as a typical microbial molecule to investigate the mechanism of opposite immune responses generated in disparate scenarios. The results of stool 16S rRNA Illumina sequencing suggested that the overwhelming number of mice pre-administered with GEMs showed the expansion of Bacteroidetes but contraction of Verrucomicrobia. Co-administration GEMs and antibiotics could preserve the microbial diversity, even though the abundance of gut microbes was largely depleted by antibiotics. Additionally, dendritic cells (DCs) from mice receiving GEMs rather than DCs that in vitro treated with GEMs induced the expansion of regulatory T cells (Tregs), witnessing the critical role of gut flora alteration. Importantly, this alteration provided protection to alleviate dextran sulfate sodium (DSS)-induced intestinal inflammation. On the other hand, in the context of Helicobacter felis (H. felis) infection, the mice pre-administrated with GEMs exhibited a comparably potent gastric immunity with the elevated expression of IFN-γ, IL-17, and multiple anti-microbial factors, leading to the reduced burden of H. felis. However, tolerance for both DSS-induced intestinal inflammation and immunity against H. felis was depleted in a mice model lacking of transforming growth factor-ß1 (TGF-ß1) in myeloid cells. These findings suggest that GEMs can modulate host immune responses bidirectionally according to context, and may serve as a supplement for antibiotic treatment.

Promoting Immune Efficacy of the Oral Helicobacter pylori Vaccine by HP55/PBCA Nanoparticles against the Gastrointestinal Environment.

The immunogenicity of oral subunit vaccines is poor partly as a result of the harsh milieu of the gastrointestinal (GI) tract. For some pathogens that restrictedly inhabit the GI tract, a vaccine that works in situ may provide more potent protection than vaccines that operate parenterally. Yet, no appropriate delivery system is available for oral subunit vaccines. In this study, we designed HP55/poly( n-butylcyanoacrylate) (PBCA) nanoparticles (NPs) to carry Helicobacter pylori ( H. pylori) subunit vaccine CCF for oral administration in a prophylactic mice model. These NPs, which are synthesized using an interfacial polymerization method, protected the CCF antigen not only from the acidic pH in simulated gastric fluid (SGF, pH 1.2) but also from the proteolysis in simulated intestinal fluid (SIF, pH 7.4). Oral vaccination of mice with HP55/PBCA-CCF NPs promoted the production of serum antigen-specific antibodies, mucosal secretory IgA, and proinflammatory cytokines. Moreover, a Th1/Th17 response and augmented lymphocytes were found in the gastric tissue of HP55/PBCA-CCF NP-immunized mice, which might eventually limit H. pylori colonization. Collectively, these results indicate that HP55/PBCA NPs are promising carriers against the severe situation of the GI tract and thereby may be further utilized for other orally administrated vaccines or drugs.

Toxic adjuvants alter the function and phenotype of dendritic cells to initiate adaptive immune responses induced by oral Helicobacter pylori vaccines.

BACKGROUND: Toxic adjuvant is considered as an indispensable constituent for oral Helicobacter pylori (H. pylori) vaccines. However, the elaborate role of toxic adjuvant in the initiation of adaptive immune response is largely undescribed. MATERIALS AND METHODS: We employed an acid-resistant HP55/PLGA nanoparticles (NPs) delivery system encapsulating three antigens (Hsp, Nap, and Lpp20) from H. pylori and accompanied with three adjuvants (LPS, CpG, and chimeric flagellum (CF)) to explore the underlying mechanism of the adjuvant constituent. H. pylori-specific antibody responses were detected by ELISA. Gastric inflammatory and Th1/Th17 responses were analyzed by flow cytometry. Expressions of inflammatory cytokines were measured by quantitative real-time PCR. RESULTS: In bone marrow-derived dendritic cells' (BMDCs) model, the addition of toxic adjuvants is responsible for the proinflammatory function, but not the mature phenotype of BMDCs. In vivo, intestinal loop injection with NPs + LPS, rather than NPs alone, altered the dendritic cell (DC) phenotypes in mesenteric lymph nodes and drove a local proinflammatory microenvironment. In a prophylactic vaccination model, mice immunized with NPs + adjuvants significantly reduced the gastric colonization of H. pylori, induced antigen-specific antibody responses and Th1/Th17 cell responses. After H. pylori challenge, these mice showed potent recall responses involving both neutrophil and inflammatory monocyte infiltration. Additionally, TLR4 knockout mice were immunized with NPs + LPS and NPs + CF, respectively; only the recipients of NPs + CF orchestrated a protective response to control bacterial infection. CONCLUSIONS: Our study indicated that toxic adjuvants within oral H.pylori vaccines altered the function and phenotype of dendritic cells and facilitated the establishment of proinflammatory microenvironment to initiate adaptive immune responses.