The Antiproliferative Effect of Cyclodipeptides from Pseudomonas aeruginosa PAO1 on HeLa Cells Involves Inhibition of Phosphorylation of Akt and S6k Kinases.

Pseudomonas aeruginosa PAO1, a potential pathogen of plants and animals, produces the cyclodipeptides cyclo(l-Pro-l-Tyr), cyclo(l-Pro-l-Phe), and cyclo(l-Pro-l-Val) (PAO1-CDPs), whose effects have been implicated in inhibition of human tumor cell line proliferation. Our purpose was to investigate in depth in the mechanisms of HeLa cell proliferation inhibition by the PAO1-CDPs. The results indicate that PAO1-CDPs, both purified individually and in mixtures, inhibited HeLa cell proliferation by arresting the cell cycle at the G0-G1 transition. The crude PAO1-CDPs mixture promoted cell death in HeLa cells in a dose-dependent manner, showing efficacy similar to that of isolated PAO1-CDPs (LD50 of 60-250 µM) and inducing apoptosis with EC50 between 0.6 and 3.0 µM. Moreover, PAO1-CDPs showed a higher proapoptotic activity (~10³-105 fold) than their synthetic analogs did. Subsequently, the PAO1-CDPs affected mitochondrial membrane potential and induced apoptosis by caspase-9-dependent pathway. The mechanism of inhibition of cells proliferation in HeLa cells involves inhibition of phosphorylation of both Akt-S473 and S6k-T389 protein kinases, showing a cyclic behavior of their expression and phosphorylation in a time and concentration-dependent fashion. Taken together our findings indicate that PI3K-Akt-mTOR-S6k signaling pathway blockage is involved in the antiproliferative effect of the PAO1-CDPs.

Salmonella Typhi OmpS1 and OmpS2 porins are potent protective immunogens with adjuvant properties.

Salmonella enterica serovar Typhi (S. Typhi) is the causal agent of typhoid fever, a disease that primarily affects developing countries. Various antigens from this bacterium have been reported to be targets of the immune response. Recently, the S. Typhi genome has been shown to encode two porins--OmpS1 and OmpS2--which are expressed at low levels under in vitro culture conditions. In this study, we demonstrate that immunizing mice with either OmpS1 or OmpS2 induced production of specific, long-term antibody titres and conferred protection against S. Typhi challenge; in particular, OmpS1 was more immunogenic and conferred greater protective effects than OmpS2. We also found that OmpS1 is a Toll-like receptor 4 (TLR4) agonist, whereas OmpS2 is a TLR2 and TLR4 agonist. Both porins induced the production of tumour necrosis factor and interleukin-6, and OmpS2 was also able to induce interleukin-10 production. Furthermore, OmpS1 induced the over-expression of MHC II molecules in dendritic cells and OmpS2 induced the over-expression of CD40 molecules in macrophages and dendritic cells. Co-immunization of OmpS1 or OmpS2 with ovalbumin (OVA) increased anti-OVA antibody titres, the duration and isotype diversity of the OVA-specific antibody response, and the proliferation of T lymphocytes. These porins also had adjuvant effects on the antibody response when co-immunized with either the Vi capsular antigen from S. Typhi or inactivated 2009 pandemic influenza A(H1N1) virus [A(H1N1)pdm09]. Taken together, the data indicate that OmpS1 and OmpS2, despite being expressed at low levels under in vitro culture conditions, are potent protective immunogens with intrinsic adjuvant properties.

Subversion of innate and adaptive immune activation induced by structurally modified lipopolysaccharide from Salmonella typhimurium.

Salmonella are successful pathogens that infect millions of people every year. During infection, Salmonella typhimurium changes the structure of its lipopolysaccharide (LPS) in response to the host environment, rendering bacteria resistant to cationic peptide lysis in vitro. However, the role of these structural changes in LPS as in vivo virulence factors and their effects on immune responses and the generation of immunity are largely unknown. We report that modified LPS are less efficient than wild-type LPS at inducing pro-inflammatory responses. The impact of this LPS-mediated subversion of innate immune responses was demonstrated by increased mortality in mice infected with a non-lethal dose of an attenuated S. typhimurium strain mixed with the modified LPS moieties. Up-regulation of co-stimulatory molecules on antigen-presenting cells and CD4(+) T-cell activation were affected by these modified LPS. Strains of S. typhimurium carrying structurally modified LPS are markedly less efficient at inducing specific antibody responses. Immunization with modified LPS moiety preparations combined with experimental antigens, induced an impaired Toll-like receptor 4-mediated adjuvant effect. Strains of S. typhimurium carrying structurally modified LPS are markedly less efficient at inducing immunity against challenge with virulent S. typhimurium. Hence, changes in S. typhimurium LPS structure impact not only on innate immune responses but also on both humoral and cellular adaptive immune responses.

[Tratamiento nutricional hiperproteico precirugía bariátrica en obesidad mórbida]. / High-protein diet in morbidity obesity patient before bariatric surgery.

OBJETIVO: Comparar la efectividad de un plan de alimentación hipocalórico hiperproteico con otro normoproteico sobre la composición corporal, los parámetros bioquímicos y las citocinas inflamatorias en pacientes obesos precirugía bariátrica sometidos a un tratamiento integral. MÉTODO: Se estudiaron 76 pacientes con un índice de masa corporal (IMC) ≥ 40 kg/m² previamente a la cirugía bariátrica. Un grupo fue tratado con una dieta hipocalórica hiperproteica y se comparó con una dieta hipocalórica normoproteica. Se evaluaron parámetros bioquímicos, parámetros antropométricos, composición corporal y valores de citocinas inflamatorias en suero al inicio y después de 4 meses de tratamiento. RESULTADOS: En ambos grupos se observó una disminución de peso, de IMC y de masa grasa, así como un incremento de la masa muscular respecto al momento basal (p < 0.05), sin diferencias entre los grupos estudiados. No se encontraron cambios en los parámetros bioquímicos ni en las concentraciones séricas de factor de necrosis tumoral (TNF) e interleucina (IL)-6 antes y después de 4 meses de tratamiento, ni entre los grupos evaluados (p > 0.05). Las concentraciones séricas de IL-1ß disminuyeron únicamente con la dieta hipocalórica normoproteica (p = 0.02). CONCLUSIONES: La dieta hipocalórica hiperproteica no muestra ventajas en la reducción de peso y grasa corporal, ni en la ganancia de masa muscular, en comparación con la dieta hipocalórica normoproteica en pacientes con obesidad mórbida precirugia bariátrica sometidos a un tratamiento integral. OBJECTIVE: Compare the effectiveness of a hyperproteic hypocaloric feeding plan with a normoproteic on body composition, biochemical parameters and inflammatory cytokines in obese pre-bariatric surgery patients in the integral treatment. METHOD: Seventy-six pre-bariatric surgery patients with body mass index (BMI) ≥ 40 kg/m² were studied. One group was treated with a hyperproteic hypocaloric diet and compared with a normoproteic hypocaloric diet. Biochemical parameters, anthropometric parameters, body composition and levels of tumor necrosis factor (TNF), interleukin (IL)-6 and IL-1ß in serum were evaluated at the initiation of treatment and after 4 months. RESULTS: In both groups studied, a decrease in weight, BMI and fat mass was observed, as well as an increase in muscle mass compared to baseline (p < 0.05), no differences showed between the groups studied. No change was found in the biochemical parameters and serum levels of TNF and IL-6 before and after 4 months of treatment, nor among the groups evaluated (p > 0.05). Serum IL-1ß levels decreased after treatment with only a normoprotein hypocaloric diet (p = 0.02). ­. CONCLUSIONS: Hyperproteic hypocaloric diet does not show advantages in weight reduction and body fat or in muscle mass gain compared to the normoproteic hypocaloric diet in patients with morbid obesity bariatric pre-surgery in the integral treatment.

Salmonella Typhi Porins OmpC and OmpF Are Potent Adjuvants for T-Dependent and T-Independent Antigens.

Several microbial components, such as bacterial DNA and flagellin, have been used as experimental vaccine adjuvants because of their inherent capacity to efficiently activate innate immune responses. Likewise, our previous work has shown that the major Salmonella Typhi (S. Typhi) outer membrane proteins OmpC and OmpF (porins) are highly immunogenic protective antigens that efficiently stimulate innate and adaptive immune responses in the absence of exogenous adjuvants. Moreover, S. Typhi porins induce the expression of costimulatory molecules on antigen-presenting cells through toll-like receptor canonical signaling pathways. However, the potential of major S. Typhi porins to be used as vaccine adjuvants remains unknown. Here, we evaluated the adjuvant properties of S. Typhi porins against a range of experimental and clinically relevant antigens. Co-immunization of S. Typhi porins with ovalbumin (OVA), an otherwise poorly immunogenic antigen, enhanced anti-OVA IgG titers, antibody class switching, and affinity maturation. This adjuvant effect was dependent on CD4+ T-cell cooperation and was associated with an increase in IFN-γ, IL-17A, and IL-2 production by OVA-specific CD4+ T cells. Furthermore, co-immunization of S. Typhi porins with an inactivated H1N1 2009 pandemic influenza virus experimental vaccine elicited higher hemagglutinating anti-influenza IgG titers, antibody class switching, and affinity maturation. Unexpectedly, co-administration of S. Typhi porins with purified, unconjugated Vi capsular polysaccharide vaccine (Vi CPS)-a T-independent antigen-induced higher IgG antibody titers and class switching. Together, our results suggest that S. Typhi porins OmpC and OmpF are versatile vaccine adjuvants, which could be used to enhance T-cell immune responses toward a Th1/Th17 profile, while improving antibody responses to otherwise poorly immunogenic T-dependent and T-independent antigens.

[Modulation of immune response by bacterial lipopolysaccharides]. / Modulación de la respuesta inmune por los lipopolisacáridos bacterianos.

Lipopolysaccharide (LPS) is a molecule that is profusely found on the outer membrane of Gram-negative bacteria and is also a potent stimulator of the immune response. As the main molecule on the bacterial surface, is also the most biologically active. The immune response of the host is activated by the recognition of LPS through Toll-like receptor 4 (TLR4) and this receptor-ligand interaction is closely linked to LPS structure. Microorganisms have evolved systems to control the expression and structure of LPS, producing structural variants that are used for modulating the host immune responses during infection. Examples of this include Helicobacter pylori, Francisella tularensis, Chlamydia trachomatis and Salmonella spp. High concentrations of LPS can cause fever, increased heart rate and lead to septic shock and death. However, at relatively low concentrations some LPS are highly active immunomodulators, which can induce non-specific resistance to invading microorganisms. The elucidation of the molecular and cellular mechanisms involved in the recognition of LPS and its structural variants has been fundamental to understand inflammation and is currently a pivotal field of research to understand the innate immune response, inflammation, the complex host-pathogen relationship and has important implications for the rational development of new immunomodulators and adjuvants.

El lipopolisacárido (LPS) se encuentra abundantemente en la membrana externa de las bacterias gramnegativas y es un potente estimulador de la respuesta inmunitaria. Al ser la molécula predominante en la superficie bacteriana también es la de mayor actividad biológica. La respuesta del sistema inmunitario del hospedero es activada por el reconocimiento molecular del LPS mediante el receptor tipo Toll 4 (TLR4), por lo que está íntimamente ligada a su estructura. Los microorganismos cuentan con sistemas que les permiten controlar la expresión y estructura del LPS, lo cual les es útil para modular la respuesta inmunitaria del hospedero y lograr la infección. Algunos ejemplos incluyen a Helicobacter pylori, Francisella tularensis, Chlamydia trachomatis y varias especies de Salmonella. Altas concentraciones de LPS pueden inducir fiebre, aumento del ritmo cardíaco y dar lugar a choque séptico y la muerte. En concentraciones relativamente bajas, algunos LPS son inmunomoduladores muy activos que pueden inducir la resistencia no específica a los microorganismos invasores. El esclarecimiento de los mecanismos moleculares y celulares involucrados en el reconocimiento del LPS y de sus variantes estructurales permite entender la respuesta inmune innata, la inflamación y la compleja relación hospedero-patógeno, para el desarrollo de nuevos inmunomoduladores y adyuvantes.

Antimycotic Activity and Genotoxic Evaluation of Citrus sinensis and Citrus latifolia Essential Oils.

The aim of this study was to evaluate the antifungal activity of essential oils (EOs) of Citrus sinensis (C. sinensis) and Citrus latifolia (C. latifolia) against five Candida species: Candida albicans, Candida tropicalis, Candida glabrata, Candida lusitaniae and Candida guilliermondii; and perform its genotoxic evaluation. The EOs of C. sinensis and C. latifolia were obtained from the peel by hydro-distillation. The major components determined by GC-MS were in C. sinensis, d-limonene (96%) and α-myrcene (2.79%); and in C. latifolia, d-limonene (51.64%), ß-thujene (14.85%), ß-pinene (12.79%) and γ-terpinene (12.8%). Antifungal properties were studied by agar diffusion method, where C. sinensis presented low activity and C. latifolia essential oil was effective to inhibit growing of C. lusitaniae and C. guilliermondii with IC50 of 6.90 and 2.92 µg respectively. The minimum inhibitory concentrations (MIC) for C. sinensis were in a range of 0.42-3.71 µg and for C. latifolia of 0.22-1.30 µg. Genotoxic evaluation was done by Ames test where none of the oils induced point mutations. Flow cytometry was used to measure toxicity in human oral epithelial cells, C. sinensis was not cytotoxic and C. latifolia was toxic at 21.8 µg. These properties might bestow different odontological applications to each essential oil.

A Toll/IL-1R/resistance domain-containing thioredoxin regulates phagocytosis in Entamoeba histolytica.

BACKGROUND: Entamoeba histolytica is a protozoan parasite that infects humans and causes amebiasis affecting developing countries. Phagocytosis of epithelial cells, erythrocytes, leucocytes, and commensal microbiota bacteria is a major pathogenic mechanism used by this parasite. A Toll/IL-1R/Resistance (TIR) domain-containing protein is required in phagocytosis in the social ameba Dictyostelium discoideum, an ameba closely related to Entamoeba histolytica in phylogeny. In insects and vertebrates, TIR domain-containing proteins regulate phagocytic and cell activation. Therefore, we investigated whether E. histolytica expresses TIR domain-containing molecules that may be involved in the phagocytosis of erythrocytes and bacteria. METHODS: Using in silico analysis we explored in Entamoeba histolytica databases for TIR domain containing sequences. After silencing TIR domain containing sequences in trophozoites by siRNA we evaluated phagocytosis of erythrocytes and bacteria. RESULTS: We identified an E. histolytica thioredoxin containing a TIR-like domain. The secondary and tertiary structure of this sequence exhibited structural similarity to TIR domain family. Thioredoxin transcripts silenced in E. histolytica trophozoites decreased erythrocytes and E. coli phagocytosis. CONCLUSION: TIR domain-containing thioredoxin of E. histolytica could be an important element in erythrocytes and bacteria phagocytosis.