Outer Membrane Vesicles Displaying a Heterologous PcrV-HitA Fusion Antigen Promote Protection against Pulmonary Pseudomonas aeruginosa Infection.

Along with surging threats and antibiotic resistance of Pseudomonas aeruginosa in health care settings, it is imperative to develop effective vaccines against P. aeruginosa infection. In this study, we used an Asd (aspartate-semialdehyde dehydrogenase)-based balanced-lethal host-vector system of a recombinant Yersinia pseudotuberculosis mutant to produce self-adjuvanting outer membrane vesicles (OMVs). The OMVs were used as a carrier to deliver the heterologous PcrV-HitAT (PH) fusion antigen of P. aeruginosa for vaccine evaluation. Intramuscular vaccination with OMVs carrying the PH antigen (referred to rOMV-PH) afforded 73% protection against intranasal challenge with 5 × 106 (25 50% lethal doses) of the cytotoxic PA103 strain and complete protection against a noncytotoxic PAO1 strain. In contrast, vaccination with the PH-deficient OMVs or PH antigen alone failed to offer effective protection against the same challenge. Immune analysis showed that the rOMV-PH vaccination induced potent humoral and Th1/Th17 responses compared to the PH vaccination. The rOMV-PH vaccination rapidly cleared P. aeruginosa burdens with coordinated production of proinflammatory cytokines in mice. Moreover, antigen-specific CD4+ and CD8+ T cells and their producing cytokines (tumor necrosis factor alpha and interleukin-17A), rather than antibodies, were essential for protection against pneumonic P. aeruginosa infection. Our studies demonstrated that the recombinant Y. pseudotuberculosis OMVs delivering heterologous P. aeruginosa antigens could be a new promising vaccine candidate for preventing the spread of drug-resistant P. aeruginosa. IMPORTANCE Hospital- and community-acquired infections with Pseudomonas aeruginosa cause a high rate of morbidity and mortality in patients who have underlying medical conditions. The spread of multidrug-resistant P. aeruginosa strains is becoming a great challenge for treatment using antibiotics. Thus, a vaccine as one of the alternative strategies is urgently required to prevent P. aeruginosa infection.

Group 2 innate lymphoid cells are numerically and functionally deficient in the triple transgenic mouse model of Alzheimer's disease.

BACKGROUND: The immune pathways in Alzheimer's disease (AD) remain incompletely understood. Our recent study indicates that tissue-resident group 2 innate lymphoid cells (ILC2) accumulate in the brain barriers of aged mice and that their activation alleviates aging-associated cognitive decline. The regulation and function of ILC2 in AD, however, remain unknown. METHODS: In this study, we examined the numbers and functional capability of ILC2 from the triple transgenic AD mice (3xTg-AD) and control wild-type mice. We investigated the effects of treatment with IL-5, a cytokine produced by ILC2, on the cognitive function of 3xTg-AD mice. RESULTS: We demonstrate that brain-associated ILC2 are numerically and functionally defective in the triple transgenic AD mouse model (3xTg-AD). The numbers of brain-associated ILC2 were greatly reduced in 7-month-old 3xTg-AD mice of both sexes, compared to those in age- and sex-matched control wild-type mice. The remaining ILC2 in 3xTg-AD mice failed to efficiently produce the type 2 cytokine IL-5 but gained the capability to express a number of proinflammatory genes. Administration of IL-5, a cytokine produced by ILC2, transiently improved spatial recognition and learning in 3xTg-AD mice. CONCLUSION: Our results collectively indicate that numerical and functional deficiency of ILC2 might contribute to the cognitive impairment of 3xTg-AD mice.

Recombinant Pseudomonas Bionanoparticles Induce Protection against Pneumonic Pseudomonas aeruginosa Infection.

To develop an effective Pseudomonas aeruginosa outer-membrane-vesicle (OMV) vaccine, we eliminated multiple virulence factors from a wild-type (WT) P. aeruginosa strain, PA103, to generate a recombinant strain, PA-m14. Strain PA-m14 was tailored with a pSMV83 plasmid carrying the pcrV-hitAT fusion gene to produce OMVs. The recombinant OMVs (termed OMV-PH) enclosed increased amounts of the PcrV-HitAT bivalent antigen (PH) and exhibited lower toxicity than did the OMVs from PA103. Intramuscular vaccination with OMV-PH from PA-m14(pSMV83) afforded 70% protection against intranasal challenge with 6.5 × 106 CFU (∼30 50% lethal doses [LD50]) of PA103, while immunization using OMVs without the PH antigen (termed OMV-NA) or the PH antigen alone failed to offer effective protection against the same challenge. Further immune analysis showed that OMV-PH immunization significantly stimulated potent antigen-specific humoral and T-cell (Th1/Th17) responses over those with PH or OMV-NA immunization in mice and that these more-potent responses can effectively hinder P. aeruginosa infection. Undiluted antisera from OMV-PH-immunized mice displayed significantly more opsonophagocytic killing of WT PA103 than antisera from PH antigen- or OMV-NA-immunized mice. Moreover, OMV-PH immunization afforded significant antibody-independent cross-protection to mice against PAO1 and the AMC-PA10 clinical isolate. Taking our findings together, the recombinant P. aeruginosa OMV delivering the bivalent PH antigen exhibits high immunogenicity and may be a promising next-generation vaccine candidate against P. aeruginosa infection.

Escherichia coli O101-induced diarrhea develops gut microbial dysbiosis in rats.

Enterotoxigenic Escherichia coli (ETEC)-induced diarrhea is a devastating disease and one of the third leading causes of infectious disease-associated mortalities worldwide. Despite recent advances in the identification of the association between gut microbiota and diarrhea, a lack of understanding exists on the status of gut microbiota in rats treated with ETEC. In the present study, a rat model of Escherichia (E.) coli O101-induced diarrhea was established. The diarrhea incidence and index, as well as histological changes, were assessed. In addition, Illumina MiSeq sequencing of V3-V4 hypervariable regions of 16S ribosomal RNA was employed to investigate the changes in the gut microbiota profiles in the feces of the diarrhea rats. The results indicated that E. coli O101 increased the diarrhea index and injury in the intestinal tissues, whereas it decreased the bacterial richness and shifted the distribution pattern of the bacterial communities in the phylum, order and genus levels in the fecal samples. Notably, the proportion of bacteria Prevotella, Enterococcus and Akkermansia was significantly decreased, while the pathogenic bacteria Escherichia/Shigella were significantly increased in diarrhea rats. Taken together, the gut microbiota is closely associated with E. coli O101-induced diarrhea in lower microbial diversity and dysbiosis of gut microbiota at different taxonomical levels.

Effect of Andrographolide on Gene Expression Profile and Intracellular Calcium in Primary Rat Myocardium Microvascular Endothelial Cells.

Andrographolide (ANDRO) is a diterpene lactone compound with extensive biological effects, such as antibacterial, antitumor and treatment of cardiovascular diseases. Until now, studies on the pharmacological functions of ANDRO are still in progress. However, little is known about the gene expression profile and calcium response of endothelial cells to ANDRO. In this study, we used a microarray technology to investigate the gene expression responses in primary rat myocardium microvascular endothelial cells treated with 10 µg/mL ANDRO. The expression of caveolin-1 and 1-phosphatidylinositol 4, 5-bisphosphate phosphodiesterase δ3 was verified by RT-PCR and western blot. In addition, we investigated the effect of ANDRO on intracellular calcium induced by exogenous adenosine triphosphate and on inflammatory response induced by lipopolysaccharide. Results showed that ANDRO treatment induced an abundance of differential expressed genes, exhibiting a multitarget regulatory effect. ANDRO significantly decreased caveolin-1 and phosphodiesterase δ3 expression, lipopolysaccharide-induced IL-6 and TNF-α levels and expression of several chemokine genes, which are associated with reducing inflammation response and decreasing calcium release without affecting normal endothelia cell function, suggesting that ANDRO may be a potential candidate to treat cardiovascular diseases with less toxicity.