Cellular immunity in healthy volunteers treated with an octavalent conjugate Pseudomonas aeruginosa vaccine

Sodium houttuyfonate effectively treats acute pulmonary infection of Pseudomonas aeruginosa by affecting immunity and intestinal flora in mice

Introduction

Pseudomonas aeruginosa is a major nosocomial pathogen that frequently causes ventilator-associated pneumonia in specific populations. Sodium houttuyfonate (SH) has shown mild antibacterial activity against P. aeruginosa in vitro, but the mechanism of potent antimicrobial activity of SH against P. aeruginosa infection in vivo remains unclear.

Methods

Here, using the mouse pneumonia model induced by P. aeruginosa nasal drip to explore the therapeutic effects of SH.

Results

We found that SH exhibits dose-dependent therapeutic effects of reducing P. aeruginosa burden and systemic inflammation in pneumonia mice. SH ameliorates inflammatory gene expression and production of inflammatory proteins, such as interleukin-6 (IL-6), nuclear factor kappa-B (NF-κB) and toll-like receptor 4 (TLR4), associated with the TLR4/NF-κB pathway in mice with P. aeruginosa pneumonia. Furthermore, we analyzed the intestinal flora of mice and found that compared with the model group, the abundance and diversity of beneficial bacterial flora of SH treatment groups increased significantly, suggesting that SH can improve the intestinal flora disorder caused by inflammation. In addition, SH improves alpha and beta diversity index and reduces species abundance differences of intestinal flora in pneumonia mice.

Discussion

Taken together, our presented results indicate that SH may effectively alleviate the acute pulmonary infection induced by P. aeruginosa by reducing the disturbance of regulating immunity and intestinal flora in mice.

Cytokine signaling pathway in cystic fibrosis: expression of SOCS and STATs genes in different clinical phenotypes of the disease

This was an observational cross-sectional study which was done to assess the expression profile of STATs and SOCS genes in cystic fibrosis. The mRNA was isolated from peripheral blood mononuclear cells of CF patients in exacerbation, colonization and post exacerbation phases of the disease. The relative gene expression level for SOCS 1, -3, -5 and STAT 1, -3,-4,-6 genes was quantified by Real-time PCR. The levels of IL-6 were also measured in the serum by ELISA. The expression of the Th1 pathway associated genes (SOCS1, SOCS5, STAT4 and STAT1) was downregulated while the expression of Th2/Th17 pathway genes (SOCS3, STAT3, STAT6) was upregulated in both exacerbation and colonization phases as compared to healthy controls. The serum levels of IL-6 were also elevated in both the disease groups. After antibiotic treatment, the expression of SOCS5 and STAT4 was increased while the expression of rest of the genes showed downregulation which shows a shift in immune response from Th2/Th17 to Th1. Our results suggest that infection alters the cytokine signaling pathway through modulation of STATs and SOCS genes which is not able to regulate the overstimulation of cytokine signaling further leading to chronic inflammation in CF.

Understanding Pseudomonas aeruginosa-Host Interactions: The Ongoing Quest for an Efficacious Vaccine

Pseudomonas aeruginosa is a leading cause of chronic respiratory infections in people with cystic fibrosis (CF), bronchiectasis or chronic obstructive pulmonary disease (COPD), and acute infections in immunocompromised individuals. The adaptability of this opportunistic pathogen has hampered the development of antimicrobial therapies, and consequently, it remains a major threat to public health. Due to its antimicrobial resistance, vaccines represent an alternative strategy to tackle the pathogen, yet despite over 50 years of research on anti-Pseudomonas vaccines, no vaccine has been licensed. Nevertheless, there have been many advances in this field, including a better understanding of the host immune response and the biology of P. aeruginosa. Multiple antigens and adjuvants have been investigated with varying results. Although the most effective protective response remains to be established, it is clear that a polarised Th2 response is sub-optimal, and a mixed Th1/Th2 or Th1/Th17 response appears beneficial. This comprehensive review collates the current understanding of the complexities of P. aeruginosa-host interactions and its implication in vaccine design, with a view to understanding the current state of Pseudomonal vaccine development and the direction of future efforts. It highlights the importance of the incorporation of appropriate adjuvants to the protective antigen to yield optimal protection.

Vaccine strategies against cystic fibrosis pathogens

A great number of cystic fibrosis (CF) pathogens such as Pseudomonas aeruginosa, the Burkholderia cepacia and the Mycobacterium abscessus complex raised difficult therapeutic problems due to their intrinsic multi-resistance to numerous antibiotics. Vaccine strategies represent one of the key weapons against these multi-resistant bacteria in a number of clinical settings like CF. Different strategies are considered in order to develop such vaccines, linked either to priming the host response, or by exploiting genomic data derived from the bacterium. Interestingly, virulence factors synthesized by various pathogens might serve as targets for vaccine development and have been, for example, evaluated in the context of CF.

A DNA vaccine encoding VP22 of herpes simplex virus type I (HSV-1) and OprF confers enhanced protection from Pseudomonas aeruginosa in mice

Pseudomonas aeruginosa antimicrobial resistance is a major therapeutic challenge. DNA vaccination is an attractive approach for antigen-specific immunotherapy against P. aeruginosa. We explored the feasibility of employing Herpes simplex virus type 1 tegument protein, VP22, as a molecular tool to enhance the immunogenicity of an OprF DNA vaccine against P. aeruginosa. Recombinant DNA vaccines, pVAX1-OprF, pVAX1-OprF-VP22 (encoding a n-OprF-VP22-c fusion protein) and pVAX1-VP22-OprF (encoding a n-VP22-OprF-c fusion protein) were constructed. The humoral and cellular immune responses and immune protective effects of these DNA vaccines in mice were evaluated. In this report, we showed that vaccination with pVAX1-OprF-VP22 induced higher levels of IgG titer, T cell proliferation rate. It also provided better immune protection against the P. aeruginosa challenge when compared to that induced by pVAX1-OprF or pVAX1-VP22-OprF DNA vaccines. Molecular mechanistic analyses indicated vaccination with pVAX1-OprF-VP22 triggered immune responses characterized by a preferential increase in antigen specific IgG2a and IFN-γ in mice, indicating Th1 polarization. We concluded that VP22 is a potent stimulatory molecular tool for DNA vaccination when fused to the carboxyl end of OprF gene. Our study provides a novel strategy for prevention and treatment of P. aeruginosa infection.

OBTENÇÃO E CARACTERIZAÇÃO DE IMUNÓGENO CONJUGADO DE LIPOPOLISSACARÍDEO DE PSEUDOMONAS AERUGINOSA E ALBUMINA BOVINA

RESUMO A Pseudomonas aeruginosa é agente etiológico de infecções oportunistas, principalmente em pacientes imunocomprometidos. Suas características inerentes em desenvolver resistência aos mais variados tipos de antibacterianos a torna um ponto crítico no controle de infecções. Em animais, os problemas com multirresistência ocorrem principalmente em casos de otite, cistite, úveo-conjuntivite, endometrite e mastite, não havendo vacina comercialmente disponível. No intuito de melhorar a imunogenicidade desse antígeno, foi testada a técnica de conjugação do lipopolissacarídeo (LPS) de P. aeruginosa à albumina bovina (BSA) por aminação redutiva direta utilizando .-periodato de sódio. A conjugação foi avaliada por cromatografia de gel-permeação, dosando-se açúcar e proteína totais, e tanto o LPS quanto a BSA foram identificados em proporções semelhantes. A imunização de camundongos com a vacina conjugada LPS-BSA conferiu títulos de anticorpos aglutinantes contra P. aeruginosa inferiores aos obtidos com a mistura de LPS e BSA livres. Foram 65% e 86% menores na 6ª e na 10ª semanas após o procedimento de hiperimunização, respectivamente. Isto indica que a reação de conjugação resultou em um produto imunogênico, porém, sua qualidade precisará ser melhorada.

Pseudomonas aeruginosa and the host pulmonary immune response

Pseudomonas aeruginosa is a highly adaptable, opportunistic pathogen that is commonly found in the environment. It can infect a number of sites in the body and disseminate. It can cause both acute and chronic pulmonary infection and the acuity of infection and accompanying inflammatory phenotype is determined, for the most part, by the host. Although P. aeruginosa has been a successful opportunist in the context of a number of different disease states, it has been best studied in the context of cystic fibrosis (CF). The adaptability of P. aeruginosa has enabled it to adjust quickly to the CF airway, transitioning from initial colonization to chronic infection. The organism quickly expresses virulence factors that allow it to circumvent some elements of the host immune response and, even more importantly, quickly develops antimicrobial resistance. In the case of CF, chronic infection resulting in progressive lung damage, coupled with antimicrobial resistance, becomes an increasingly important issue as individuals with CF live longer. It is for these reasons that both organism- and host-targeted immunotherapies are being increasingly explored.

Protection against Pseudomonas aeruginosa lung infection in mice by recombinant OprF-pulsed dendritic cell immunization

BACKGROUND

The Pseudomonas aeruginosa major constitutive outer membrane porin protein F (OprF) has been shown to be a protective antigen and was previously used to activate an immunological response in a mouse model of lung pneumonia. The purpose of our study was to demonstrate the ability of mouse dendritic cells pulsed with purified or recombinant OprF to protect mice against P. aeruginosa infection and inflammation.Both native (n-OprF), isolated and purified from PAO1 bacterial strain, and recombinant (histidin-conjugated) OprF (His-OprF), obtained by cloning of the oprF gene into the pET28a expression vector, were used to stimulate dendritic cells in vitro before adoptive transfer into prospective recipient mice with P. aeruginosa pulmonary infection.

RESULTS

Similar to n-OprF, His-OprF activated dendritic cells in vitro, inducing the costimulatory molecule expression as well as cytokine production. Upon adoptive transfer in vivo, porin-pulsed dendritic cells (DCs) induced Th1-mediated resistance to infection and associated inflammatory pathology caused by either the PAO1 strain or a clinically-isolated mucoid strain.

CONCLUSIONS

This study highlights the pivotal contribution of DCs to vaccine-induced protection against P. aeruginosa infection and associated inflammation.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Assessment of humoral and cell-mediated immunity against Bordetella pertussis in adolescent, adult, and senior subjects in Italy

Humoral and cell-mediated immunity (CMI) against B. pertussis was assessed in a sample of adolescent, adult and senior subjects distributed in five different geographical areas in Italy. Most (99.1%) subjects had IgG anti-pertussis toxin (PT) antibodies exceeding the minimum detection level [> or = 2 ELISA units (EU)/ml]. There were no significant differences between the genders; 6.2% samples recorded titres > or = 100 EU/ml. CMI was positive [stimulation index (SI) > or = 5] against PT in 39.0% of all samples. This study suggests that B. pertussis continues to circulate in age groups that have been previously considered to be uninvolved in the circulation of this pathogen and that adolescent and adult pertussis boosters may be of value in these populations. Nevertheless, over the last 10 years, large increases in vaccination coverage rates have contributed to reduce the spread of the aetiological agent, especially in the immunized population.

Stenotrophomonas maltophilia: changing spectrum of a serious bacterial pathogen in patients with cancer

Stenotrophomonas maltophilia colonization/infection in patients with cancer has significantly increased over the past 2 decades. Patients with prolonged neutropenia, exposure to broad-spectrum antibiotics, and those requiring mechanical ventilation have higher risk of infection. These micro-organisms are intrinsically resistant to carbapenems, and exposure to these agents has been linked to selection of S. maltophilia. Recently, these infections are being documented in patients without traditional risk factors. The spectrum of infection includes bacteremia, catheter-related infection, pneumonia, complicated biliary and urinary tract infection, and skin and skin-structure infection. Trimethoprim-sulfamethoxazole is the therapeutic agent of choice, but resistance is increasingly being reported. Susceptibility to alternative agents is unpredictable. Combination therapy and alternative routes of drug administration, such as aerosolized aminoglycoside, might be necessary. New insights into the mechanisms of drug resistance might lead to identification of new target sites. Agents that improve outer-membrane permeability and broad-spectrum beta-lactamase inhibitors may favorably impact difficult-to-treat (i.e., multidrug resistant) S. maltophilia infections.

Role of PAR2 in murine pulmonary pseudomonal infection

Proteinases can influence lung inflammation by various mechanisms, including via cleavage and activation of protease-activated receptors (PAR) such as PAR2. In addition, proteinases such as neutrophil and/or Pseudomonas-derived elastase can disarm PAR2 resulting in loss of PAR2 signaling. Currently, the role of PAR2 in host defense against bacterial infection is not known. Using a murine model of acute Pseudomonas aeruginosa pneumonia, we examined differences in the pulmonary inflammatory response between wild-type and PAR2(-/-) mice. Compared with wild-type mice, PAR2(-/-) mice displayed more severe lung inflammation and injury in response to P. aeruginosa infection as indicated by higher bronchoalveolar lavage fluid neutrophil numbers, protein concentration, and TNF-alpha levels. By contrast, IFN-gamma levels were markedly reduced in PAR2(-/-) compared with wild-type mice. Importantly, clearance of P. aeruginosa was diminished in PAR2(-/-) mice. In vitro testing revealed that PAR2(-/-) neutrophils killed significantly less bacteria than wild-type murine neutrophils. Further, both neutrophils and macrophages from PAR2(-/-) mice displayed significantly reduced phagocytic efficiency compared with wild-type phagocytes. Stimulation of PAR2 on macrophages using a PAR2-activating peptide resulted in enhanced phagocytosis directly implicating PAR2 signaling in the phagocytic process. We conclude that genetic deletion of PAR2 is associated with decreased clearance of P. aeruginosa. Our data suggest that a deficiency in IFN-gamma production and impaired bacterial phagocytosis are two potential mechanisms responsible for this defect.