Kit activates interleukin-4 receptor and effector signal transducer and activator of transcription 6 independent of its cognate ligand in mouse mast cells.

Signaling by Kit has been extensively studied in hematopoietic cells and is essential for the survival, proliferation and maintenance of hematopoietic stem and progenitor cells. In addition to the activation of intrinsic signaling pathways, Kit has been shown to interact with lineage-restricted type I cytokine receptors and produce cross signals, e.g. erythropoietin receptor, interleukin-7 receptor (IL-7R), IL-3R. Based on the earlier studies, we hypothesize that Kit activate other type I cytokine receptors in a cell-specific manner and execute cell-specific function. To investigate other Kit-activated receptors, we tested Kit and IL-4R cross-receptor activation in murine bone-marrow-derived mast cells, which express both Kit and IL-4R at the surface level. Kit upon activation by Kit ligand (KL), activated IL-4Rα, γC , and signal transducer and activator of transcription 6 independent of its cognate ligand IL-4. Though KL and IL-4 are individually mitogenic, combinations of KL and IL-4 synergistically promoted mast cell proliferation. Furthermore, inhibition of lipid raft formation by methyl-ß-cyclodextrin resulted in loss of synergistic proliferation. Together the data suggest IL-4R as a novel Kit-activated receptor. Such cross-receptor activations are likely to be a universal mechanism of Kit signaling in hematopoiesis.

Molecular characterization of Enterococcus faecalis isolates from urinary tract infection and interaction between Enterococcus faecalis encountered Dendritic and Natural Killer cells.

PURPOSE: Enterococcus faecalis is an emerging nosocomial pathogen. The study investigates the E. faecalis specific innate immune cells interplay between Natural Killer cells (NK) and Dendritic cells (DCs) in vitro. The present study also determines the prevalence, phenotype, and genotype of Enterococcus faecalis isolated from paediatric patients with urinary tract infection. MATERIALS AND METHODS: A total of 14 clinical isolates of Enterococcus spp were characterized using standard phenotypic tests and virulence factors were determined by polymerase chain reaction (PCR). Immature monocyte-derived DCs were cultured in the presence of six pathogenic E. faecalis isolates infected DCs were co-cultured with NK cells. Bacteria induced matured DCs and activated NK cells were evaluated by polychromatic flow cytometry. RESULTS: Out of 14 isolates, 13 were identified as E. faecalis. E. faecalis infected DCs differentiated into inflammatory and CD141 + DCs that promote NK cell activation. Activated NK cells significantly elevated the secretion of cytokines and chemokines in infected DCs during E. faecalis. This suggests that DC induced NK cell activation is effectively enhanced by the presence of E. faecalis. CONCLUSIONS: Studies on virulence determinants are necessary to understand the pathogenesis of E. faecalis. DC/NK cross-talk is of particular importance at mucosal surfaces such as the intestine, urinary tract where the immune system exists in intimate association with commensal bacteria. We found E. faecalis specific NK cells activation by infected DC-derived effector signals may involve in the killing of transformed or infected cells, thus coordinating innate and adaptive immune responses. E. faecalis specific DC/NK interaction is necessary for DC maturation and modulation of innate effector functions. Similarly, activated NK cells that induce- maturation of DC by pattern recognition receptors are also required for the generation of bacterial specific adaptive immunity.

Pseudomonas aeruginosa infection stimulates mitogen-activated protein kinases signaling pathway in human megakaryocytes.

Pseudomonas aeruginosa is a major cause of nosocomial infections and contributes to higher mortality in hospitalized individuals. Infection by P. aeruginosa triggers host immune response through activation of pathogen recognition receptors, which are present in innate cells. Several studies have reported the mechanism of P. aeruginosa induced innate immunity in multiple cell types. But so far there is no reports on response of megakaryocytes to P. aeruginosa infection. Hence, our aim was to investigate the precise role and signaling mechanism of megakaryocytes during P. aeruginosa infection. In this study, we used Mo7e cells as representatives of human megakaryocyte and found that P. aeruginosa infection induces cytotoxicity in these cells. We further demonstrated that P. aeruginosa infection modulates p38 and extracellular signal regulated kinase pathways in Mo7e cells. Protein expression profiling in P. aeruginosa lipopolysaccharide-treated Mo7e cells revealed upregulation of importin subunit ß and downregulation of metabolic enzymes. Our results suggest that P. aeruginosa infection regulates mitogen-activated protein kinases signaling pathway and importin in Mo7e cells and that this is a potential mechanism for nuclear translocation of nuclear factor binding near the κ light-chain gene in B cells and c-Jun N-terminal kinases to induce cell cytotoxicity.

Chitosan with pendant (E)-5-((4-acetylphenyl)diazenyl)-6-aminouracil groups as synergetic antimicrobial agents.

Conventional antimicrobial agents are losing the war against drug resistance day-by-day. Chitosan biopolymer is one of the alternative materials that lends itself well to this application by fine-tuning its bioactivity using different pendant groups. Herein, we report the synthesis of novel chitosan with pendant (E)-5-((4-acetylphenyl)diazenyl)-6-aminouracil (APAU) groups by forming Schiff base linkages between chitosan and the pendant groups. These chitosan biopolymers with pendant APAU groups form films superior in thermal stability compared to the neat chitosan. Interestingly, APAU alone was inactive against K. pneumoniae, E. coli, S. aureus, T. rubrum and C. albicans. However, novel chitosan samples were active against S. aureus with an MIC of 390 µg mL-1, half that of plain chitosan at 780 µg mL-1. APAU modified chitosan samples, CA80 and CA100 showed an MIC (against K. pneumoniae and E. coli) of 23.4 µg mL-1, superior to plain chitosan's MIC of 187.5 µg mL-1 and is close to commercial Fluconazole's MIC of 11.7 µg mL-1. The activity of chitosan changes with APAU content and at higher concentrations shows a strong synergetic antimicrobial effect.

Uracil derivatives as HIV-1 capsid protein inhibitors: design, in silico, in vitro and cytotoxicity studies.

A series of novel uracil derivatives such as bispyrimidine dione and tetrapyrimidine dione derivatives were designed based on the existing four-point pharmacophore model as effective HIV capsid protein inhibitors. The compounds were initially docked with an HIV capsid protein monomer to rationalize the ideas of design and to find the potential binding modes. The successful design and computational studies led to the synthesis of bispyrimidine dione and tetrapyrimidine dione derivatives from uracil and aromatic aldehydes in the presence of HCl using novel methodology. The in vitro evaluation in HIV p24 assay revealed five potential uracil derivatives with IC50 values ranging from 191.5 µg ml-1 to 62.5 µg ml-1. The meta-chloro substituted uracil compound 9a showed promising activity with an IC50 value of 62.5 µg ml-1 which is well correlated with the computational studies. As expected, all the active compounds were noncytotoxic in BA/F3 and Mo7e cell lines highlighting the thoughtful design. The structure activity relationship indicates the position priority and lower log P values as the possible cause of inhibitory potential of the uracil compounds.

Indole chalcones: Design, synthesis, in vitro and in silico evaluation against Mycobacterium tuberculosis.

Indole chalcones were designed and synthesized as a promising set of compounds against H37Rv strain of Mycobacterium tuberculosis. Within this library of compounds, (E)-1-(furan-3-yl)-3-(1H-indol-3-yl)prop-2-en-1-one (18), (E)-3-(1H-indol-3-yl)-1-(thiophen-2-yl)prop-2-en-1-one (20) and (E)-2-((1H-indol-2-yl)methylene)cyclopentan-1-one (24) displayed high anti-tubercular activity at 50 µg/ml with MIC values of 210, 197 and 236 µM respectively. The in-silico studies revealed that compound 18 exhibit binding modes similar to FAS-II inhibitors like INH or Thiolactomycin against KasA protein. Cytotoxicity assay results suggest that the compounds 18, 20 and 24 are non-cytotoxic to human megakaryocytes and murine B cells.